WILSON’S ANATOMIST’S VADE MECUM WILSON’S ANATOMIST'S VADE MECUM A SYSTEM OF HUMAN ANATOMY. ELEVENTH EDITION EDITED BY HENRY EDWARD CLARE FELLOW OF THE FACULTY OF PHYSICIANS AND SURGEONS OF GLASGOW MEMBER OF THE ROYAL COLLEGE OF SURGEONS OF ENGLAND PROFESSOR OF ANATOMY IN ST. MUNGO’S COLLEGE, GLASGOW PHILADELPHIA l*. BLAKISTON, SON & CO 1012 WALNUT STREET 1892 PREFACE TO THE ELEVENTH EDITION. The title of Vade Mecum, given to this work by the author, Sir Erasmus Wilson, indicated an intention that it should he a portable manual, containing all that an ordinary student required to know of human anatomy, but not discussing disputed points, or attempting to give everything that could be said on each anatomical detail. The editor of the present edition has endeavoured to act up to this intention, and consequently has neither increased the size of the pages, nor added materially to their number. He cannot claim for this edition that it contains any novel features, or is distinguished from its predecessors by startling changes; hut he has left no part untouched by revision, and has endeavoured to make the work fairly represent the present state of anatomical knowledge. The description of the central nervous system has under- gone more change than any other part of the hook; hut, while giving the results of the latest investigations, no change has been made for the mere sake of change, and the rage for new names, which seems at present to afflict anatomists, has been kept (it is hoped), within reasonable limits. Finding it impossible in the space at his disposal to give a complete description of the development of the embryo, the editor has thought it best to omit altogether the paragraphs vi which in the last edition gave some particulars of the develop- ment of certain organs, as these presupposed a knowledge of the earlier stages of embryonic evolution. Tiie Yade Mecum in its earliest editions was distinguished by the number and excellence of its illustrations, and was, indeed, a pioneer work in this respect. Now, when wood- cuts are so numerous in anatomical works that they not un- frequently outnumber the pages, such a reputation is not easy to maintain. Very numerous additions have, however, been made in this department; they have been drawn from various British and foreign sources, and their origin is in every instance acknowledged in the List of Illustrations at the beginning of the work. It is interesting to notice that, while the woodcuts in the first edition (1840) numbered 150, they have now reached a total of nearly 500. PREFACE. 24 India Street, Glasgow, August 1892. CONTENTS. PART I. HISTOLOGY. PAGE Muscle. . . . . . 2 7 Striated . . . . .28 Non-striated . . . . 31 Heart muscle . . . . 31 Nerve tissue . . . • 32 Nerve fibres . . . -33 Nerve cells . . . -35 Ganglia . • • . -37 Nerve terminations . . -39 Sympathetic nerve . . • 41 Blood-vessels . . . .42 Arteries . . - . -43 Capillaries . . -47 Veins . . • • -49 Lymphatics 51 Serous membranes . . • 56 Synovial membranes . . -57 Mucous membrane . . -59 Secreting glands . - • .60 Skin and its appendages . . 63 Derma . . • • -63 Epidermis . . . -64 Nails . . • • .68 Hairs 68 Sebaceous glands . . -7° Sudoriferous glands. . • 71 Definition of histology . • 1 Cells and protoplasm . . . 1 Blood 4 Lymph and chyle ... 6 Epithelium 7 Connective tissue . . .11 Areolar tissue . . . .11 Adipose tissue . . • • I3 Fibrous tissue . . • . 13 Yellow or elastic tissue . . 14 Mucous tissue . . . 15 Reticular tissue . . .16 Simple membrane . . .16 Pigment 16 Cartilage . . . ... 17 Hyaline cartilage . . .17 Elastic cartilage . • .18 Fibro-cartilage. . . . 19 Bone ...... 20 Structure of bone . • .20 Periosteum . . . .21 Minute structure of bone. . 21 Medulla 23 Development of bone . . .24 Intramembranous . . .24 Intracartilaginous . . .25 PART II. OSTEOLOGY. Number of bones in the skeleton . 73 General characters of bones . 73 Vertebral column . . -74 Cervical vertebrae . . -75 Dorsal vertebrae . . . 78 Lumbar vertebrae . . .80 General considerations . . 80 Development . . . .81 Attachment of muscles . . 83 Sacrum 84 viii PAGE Coccyx 86 Bones of the cranium . . 87 Occipital bone ... 87 Parietal bone.... 90 Frontal bone .... 92 Temporal bone ... 94 Sphenoid bone . . . 100 Ethmoid bone . . . 105 Bones of the face . . 107 Nasal bone .... 107 Superior maxillary. . . 107 Lachrymal bone . . .111 Malar bone . . . .112 Palate bone . . . . 113 Inferior turbinated . . 115 Vomer . . . . .116 Inferior maxillary . . . 117 Sutures 120 Regions of the skull . . . 121 Base of the skull . . . 123 Face 127 Orbits 127 Spheno-maxillary fossa . . 128 Nasal fossae .... 129 Os hyoides..... 131 Thorax ..... 131 Sternum .... 131 CONTENTS. PAGE Ribs 133 Costal cartilages . . . 135 Thorax as a whole . . .136 Upper extremity . . . 136 Clavicle . . . . .136 Scapula 137 Humerus .... 140 Ulna 143 Radius 145 Carpus ..... 146 Metacarpus .... 151 Phalanges . . . . 153 Pelvis and lower extremity . 153 Os innominatum . . . 153 Ilium 154 Ischium ..... 155 Pubes 156 Pelvis ..... 158 Femur 160 Patella 163 Tibia 164 Fibula ..... 166 Tarsus . . . , . 167 Metatarsal bones . . . 172 Phalanges .... 173 Sesamoid bones .... 174 PART III. ARTHROLOGY. Forms of articulation . . 175 Structures forming joints . . 175 Bursae mucosae .... 177 Table of articulations . . 178 Synarthrosis . . . .178 Amphi-arthrosis . . . 179 Diartbrosis .... 179 Movements of joints . . .180 Ligaments op the trunk . . 181 Articulation of vertebral column .... 182 Atlas with occipital bone . 185 Axis with occipital bone . 186 Atlas and axis . . . 187 Temporo-maxillary ai’ticulation 188 Ribs with vertebrae . . 190 Costal cartilages, with ster- num, and each other . 192 Ribs with costal cartilages . 193 Articulations of sternum . 193 Vertebral column with pelvis. 193 Articulations of pelvis . . 193 Upper extremity . . . 197 Sterno-clavicular . . . 197 Scapulo-clavicular . . . 199 Shoulder- joint . . . 201 Elbow-joint .... 202 Radio-ulnar articulation . 204 Wrist-joint .... 205 Carpal articulations . . 207 Carpo-metacarpal . . . 208 Metacarpo-phalangeal . . 209 Articulation of phalanges . 210 Lower extremity . . .210 Hip-joint .... 210 Knee-joint . . . .213 Tibio-fibular articulation . 218 Ankle-joint .... 220 Articulation of tarsus . . 222 Tarso-metatarsal joints . . 225 Metatarso-phalangeal . . 225 Articulation of phalanges . 226 CONTENTS. IX PART IY. PAGE General arrangement of muscles 227 Nomenclature . . . 227 Fascia ..... 228 Areolo-fibrous . . 228 Deep . . . . . 228 Head and face . . . 229 Cranial group . . . 229 Orbital group.... 231 Auricular group . . . 233 Ocular group .... 234 Nasal group .... 238 Superior labial group . . 240 Inferior labial group . . 242 Maxillary group . . . 243 Muscles and fascia: of the NECK .... 247 Superficial group . . . 247 Regional anatomy of neck . 251 Depressors of os hyoides and larynx .... 252 Elevators of os hyoides . . 254 Muscles of the tongue . . 256 Muscles of the pharynx . . 259 Muscles of the soft palate . 263 Proevertebral muscles . . 266 Muscles and fascia: of the TRUNK .... 268 Muscles of the back . . 269 First layer .... 269 Second layer . . . 272 Third layer . . . 273 Fourth layer . . . 274 Fifth layer .... 277 Sixth layer .... 278 MYOLOGY. PAGE Muscles of the thorax . . 281 Muscles of the abdomen. . 284 Fasciae of the abdomen . . 286 Anatomy of inguinal hernia . 296 Muscles of posterior wall of abdomen, and diaphragm. 298 Muscles of male perineum . 302 Perineal fasciae . . . 303 Muscles of female perineum . 308 Pelvic fascia . . . .311 Upper extremity . . .315 Fasciae of the upper extremity 315 Anterior thoracic region . 317 Lateral thoracic region . -319 Anterior scapular region . 320 Posterior scapular region . 320 Acromial region . . . 323 Anterior humeral region . 324 Posterior humeral region . 326 Anterior brachial region . 327 Posterior brachial region . 332 Muscles of the hand . . 338 Lower extremity . . . 343 Fasciae of the lower extremity 343 Femoral hernia . . . 346 Gluteal region . . . 348 Anterior femoral region. . 352 Internal femoral region . . 357 Posterior femoral region . 361 Anterior tibial region . . 363 Posterior tibial region . . 365 Fibular region . . . 370 Foot—Dorsal region . 371 Plantar region . . . 372 PART V. ANGIOLOGY. Arteries 377 Aol'ta 3 77 Table of branches . . 380 Coronary arteries . . . 380 Innominate artery. . . 381 Common carotid arteries . 381 External carotid artery . . 383 Table of branches . . 383 Superior thyroid artery . 383 Lingual artery . . . 385 Facial artery . . . 386 Occipital artery . . . 388 Posterior auricular artery . 388 Ascendingpharyngealartery 388 Parotidean arteries . . 389 Temporal artery. . . 389 Internal maxillary artery . 390 Internal carotid artery . . 393 Ophthalmic artery . . 394 Anterior cerebral artery . 397 Middle cerebral artery . 397 Subclavian artery . . . 397 Table of branches . . 399 Vertebral artery . . 399 CONTENTS. PAGE Basilar artery . . . 400 Circle of Willis . . . 402 Internal mammary artery . 402 Inferior thyroid artery . 403 Supra-scapular artery . 404 Transversalis colli artery . 404 Superior intercostal artery. 405 Axillary artery . . . 405 Table of branches . . 407 Brachial artery . . . 409 Bend of the elbow . . . 410 Radial artery. . . .411 Ulnar artery .... 414 Thoracic aorta; branches . 416 Abdominal aorta ; branches . 418 Phrenic arteries . . . 419 Coeliac axis . . . . 419 Gastric artery . . . 419 Hepatic artery . . . 419 Splenic artery . . . 422 Superior mesenteric artery. 422 Spermatic arteries . . 424 Inferior mesenteric artery . 424 Renal arteries . . . 426 Common iliac arteries . . 427 Internal iliac artery . . 427 Obturator artery . . 429 Ischiatic artery . . . 430 Internal pudic artery . . 430 Ilio-lumbar artery . . 432 Lateral sacral arteries . 433 Gluteal artery . . . 433 External iliac artery . . 434 Deep epigastric artery . 434 Triangle of Hesselbach . 435 Deep circumflex iliac artery 435 Femoral artery . . . 435 PAGK Profunda femoris artery . 438 Popliteal space . . . 440 Popliteal artery . . . 441 Anterior tibial artery . . 442 Dorsalis pedis artery . . 444 Posterior tibial artery . . 445 Peroneal artery . . . 446 Plantar arteries . . . 447 Pulmonary artery . . . 449 Veins 449 Veins of the head and neck . 450 Veins of the diploe . . 452 Cerebral and cerebellar veins 453 Sinuses of the dura mater . 454 Ophthalmic veins . . . 458 Veins of the neck . . . 458 Veins of the upper extremity 460 Veins of the lower extremity. 462 Veins of the trunk . . . 463 Brachio-cephalic veins . . 464 Superior vena cava 464 Iliac veins .... 464 Inferior vena cava . . . 466 Azygos veins .... 468 Vertebral and spinal veius . 469 Cardiac veins .... 470 Portal vein .... 471 Pulmonary veins . . . 473 Lymphatics .... 474 Lymphatics of head and neck 474 Lymphatics of upper extremity 476 Lymphatics of lower extremity 477 Lymphatics of the trunk . 479 Lymphatics of the viscera . 480 Lacteals .... 482 Thoracic duct . . . 482 Ductus lymphaticus dexter . 484 PART VI. NEUROLOGY. Cerebro-spinal axis . . . 485 Spinal cord .... 485 Medulla oblongata . . . 491 Pons Yarolii .... 496 Cerebrum 497 Base of the brain . . . 497 Convolutions and sulci . . 501 Inner surface of hemi- sphere .... 503 Structure of the convolutions 505 Interior of cerebrum . . 506 Cerebellum .... 516 Fourth ventricle . . .519 Transverse section of cerebrum 521 Transverse section of crura cerebri .... 523 Lining-of ventricles . . . 524 White matter of cerebrum . 524 Arteries of the brain. . . 525 Topography of the brain . . 528 Membranes of the brain . . 529 Membranes of the spinal cord . 534 Cranial nerves .... 536 Olfactory .... 536 Optic 537 Motores oculorum . . . 538 Pathetici .... 539 Trifacial..... 539 CONTENTS. XI PAGE Abducentes .... 547 Facial ..... 548 Auditory .... 551 Glosso-pharyngeal . . . 553 Pneumogastric . . . 555 Spinal accessory . . . 559 Hypoglossal .... 560 Spinal nerves .... 562 Cervical plexus . . . 565 Brachial plexus . . . 568 Dorsal nerves. . . . 578 PAGE Lumbar nerves . . . 581 Sacral nerves .... 588 Sympathetic nerves . . . 597 Cranial ganglia . . . 597 Cervical ganglia . . . 602 Thoracic ganglia . . . 607 Lumbar ganglia . . . 609 Pelvic plexuses . . . 610 Sacral ganglia . . . 610 Coccygeal gland . . .611 THE ORGANS OF SENSE. Organ of smell . . . .611 Nose ..... 611 Nasal fossae .... 613 Organ of vision .... 615 Appendages of the eye . . 616 Lachrymal apparatus . . 620 Globe of the eye . . . 621 Sclerotic and cornea . .621 Choroid coat .... 624 Iris and ciliary muscle . . 625 Retina ..... 627 Refracting media . . . 631 Vessels and nerves of eye . 633 Organ of hearing . . . 633 External ear .... 633 Tympanum .... 637 Internal ear .... 643 Osseous labyrinth . . . 643 Vestibule .... 644 Semicircular canals . . 644 Cochlea ..... 645 Membranous labyrinth . . 646 Vessels and nerves of internal ear ..... 651 Organ of taste .... 652 Taste-buds .... 655 PART VII. SPLANCHNOLOGY. Thorax 657 Pericardium .... 658 Heart ..... 659 Structure of the heart . 670 Foetal heart and foetal circu- lation .... 672 Organs of respiration and voice 675 Larynx .... 675 Trachea .... 684 Thyroid body . . . 685 Lungs..... 686 Pleurae .... 693 Mediastinum . . . 693 Thymus body . . . 695 Abdomen 696 Peritoneum .... 697 Alimentary canal . . . 703 Cheeks .... 703 Soft palate .... 705 Tonsils .... 705 Glands .... 706 Salivary glands . . . 707 Teeth 709 Structure . . . 712 Development . . . 715 Formation of the hard tissues .... 718 Eruption .... 719 Succession . . . 720 Pharynx .... 720 (Esophagus.... 722 Stomach .... 723 Small intestines . . . 727 Large intestine . . . 735 Liver ..... 740 Gall bladder .... 750 Pancreas . . . .751 Spleen 753 Supra-renal bodies. . . 756 Kidneys ..... 758 Pelvis 765 Bladder ..... 765 Prostate gland . . . 769 Vesiculae seminales . . 770 Male organs of generation. 771 Penis ..... 771 Urethra ..... 774 Testicles. .... 778 Testicles in the embryo . 783 Descent of testicle . . 784 XII CONTENTS. PAGE Female pelvis .... 785 Bladder ..... 785 Urethra ..... 785 Vagina 786 Uterus ..... 787 PAQE Fallopian tubes . . -791 Ovaries ..... 792 External organs of genera- tion ..... 795 Mammary glands . . . 798 Glossary of Anatomical Terms 801 Index 822 LIST OF ILLUSTRATIONS. FIGS. PAGE 1. Different kinds of cells Frey 2 2. Intercellular and internuclear networks in cells . . Klein 2 3. Diagram of karvostenosis .... -1/ Kendrick 3 4. Stages of karyokinesis ..... Gegenbaur 3 5. Red blood corpuscles ..... Stirling 3 6. White blood corpuscles ..... Stirling 5 7. Old squamous epithelial cells ... . . . Frey 8 8. Prickle cells of rete mucosum ..... Frey 8 9. Columnar epithelium from villus . . . KolHker 8 10. Columnar epithelium from small intestine . . • Hade 9 11. Columnar epithelium viewed from the surface of the membrane . 9 12. Goblet cells from intestinal villus . . Frey, after Sehvltze 9 13. Spheroidal cells of a sebaceous gland .... Frey 9 14. Cells of ciliated epithelium of nose . . • ■ 10 15. Ciliated cells with branching processes. . . ■ Klein 10 16. Endothelium ...... Stirling 11 17. Connective tissue ...... Frey 12 18. Areolar and adipose tissue .... . Mandl 13 19. Fat vesicles from omentum ..... Klein 13 20. White fibrous tissue . . . • • 21. Caudal tendon of rat, showing cells .... Bruce 14 22. Yellow or elastic tissue ..... Gurdiat 15 23. Anastomosing elastic tissue ..... Gerber 15 24. Fenestrated elastic membrane .... Kolhker 16 25. Reticular tissue ....••* Frey 16 26. Pigment cells from lamina fusca .... Frey 17 27. Pigmentary layer of retina .... Kolliker ly 28. Branchial cartilage of tadpole .... Carpenter 18 29. Elastic fibro-cartilage ..... Cardiat 18 30. White fibro-cartilage ..... Cardiat 19 31. Section of head of tibia . . . . • O. Buchanan 20 32. Section of the body of a vertebra . . . G. Buchanan 21 33. Plan of a section of a long bone. . . . G. Buchanan 21 34. Vertical section of tibia, with Haversian canals . . Mandl 22 35. Minute structure of bone . . • . • • 23 36. Lacunae of bone ....... Mandl 23 37 Intramembranous ossification .... Gegenbaur 24 38. Development of bone from cartilage . . Kolliker 25 39. Invasion of cartilage by periosteal osteoblasts . . . Stbhr 25 40. Development of bone from cartilage .... Muller 26 41. Striated muscular fibre, showing sarcolemma . . . Frey 28 LIST OF ILLUSTRATIONS FIGS. page 42. Striated muscular fibre, showing discs and fibrilhe . . Frey 29 43. Striated muscle, showing secondary striae . . Sharpey 30 44. Non-striated muscular fibres ..... Klein 30 45. Fibres of heart muscle ..... Frey 31 46. Nerve fibres of various kinds .... Wagner 32 47. Medullated nerve fibre .... Carpenter 33 48. Gelatinous nerve fibres, from olfactory nerve . Ecker 35 49. Multipolar nerve cells from spinal cord of dog-fish . Cardiat 35 50. Multipolar ganglion cells from brain .... Frey 36 51. Sympathetic ganglion ...... Frey 37 52. Ganglionic nerve cells. . . . Arnold and Beale 38 53. Section of a small nerve ..... Klein 38 54. Digital nerve with Pacinian corpuscles . . Kolliker 40 1 55. Pacinian corpuscle from mesentery of cat . Frey 40 56. End-bulbs of Krause ...... Frey 41 57. Structure of a small artery ..... Frey 44 58. Muscular fibres from the middle coat of an artery . Kolliker 45 59. Fenestrated membrane from middle coat . . Kolliker 45 60. Transverse section of the coats of an artery . . Schafer 46 ' 61. Endothelial cells lining an artery . . . Schafer 46 ; 62. Minute artery and capillary, showing nuclei in the walls Kolliker 48 63. Valves of veins ..... Sharpey 51 J 64. Lymphatic capillaries ...... Klein 52 | 65. Epithelium of serous membrane, showing stomata . . Klein 54 66. View of a lymphatic gland .... Kolliker 54 67. Section of a small lymphatic gland .... Frey 55 | 68. Medullary part of a lymphatic gland, showing lymph path Klein 55 4 69. Plan of a serous membrane . . . . G. Buchanan 56 % 70. Endothelium of peritoneum ..... Klein 57 j 71. Goblet cell from the trachea of a cat. . . Klein 60 ■, 72. Diagrams of simple glands . . . . . . 61 | 73. Diagrams of compound glands . . . . 611 74. Modes of termination of nerves in salivary glands . PJliiger 62 I 75. Vertical section of the skin ..... Ecker 63 1 76. Cells of the epidermis .... Schafer after Ranvier 65 j 77. Diagram of the development of epidermis . . . 66 1 78. Tactile papillae. ...... Frey 611 79. Hairs and their connections .... Kolliker 67 J 80. Section of a hair follicle . Schafer after Biesiadecki 691 8r. Sebaceous gland . . . . . . Frey 79 1 82. Sudoriferous gland ...... Frey 701 83. A middle cervical vertebra . . . . 761 84. Upper surface of atlas . . . 76 : 85. Lateral view of axis . . . . 77 j 86. Lateral view of a dorsal vertebra . . . 78 ; 87. Peculiar dorsal vertebrae . . . . 79 | 88. Lateral view of a lumbar vertebra . .80 89. Posterior and lateral view of spinal column . . Quoin 82 90. Anterior surface of sacrum . . .84 91. Posterior surface of sacrum . . 85 92. Anterior view of coccyx . . .86 93. External surface of occipital bone .88 94. Internal surface of occipital bone . 89 95. External surface of parietal bone . 90 ' 96. Internal surface of parietal bone . 91 j 97. External surface of frontal bone .92 98. Internal surface of frontal bone -94 LIST OF ILLUSTRATIONS. FIGS. PAGE 99. Articulation of neighbouring bones with nasal spine of frontal A. M‘Alister 94 100. External surface of temporal bone . . . . *95 101. Section through external auditory meatus . . . .96 102. Basilar surface of temporal bone . . . H. E. Clark 97 103. Internal surface of temporal bone . . . . -98 104. Tympanic ring. . . . . . . .99 105. Superior surface of sphenoid bone ..... 101 106. Antero-inferior view of sphenoid bone .... 102 107. Ethmoid bone 105 108. Nasal bone of left side ...... 107 109. Lateral view of superior maxillary bone .... 108 no. Internal view of superior maxillary bone .... 109 in. Right lachrymal bone . ...... 111 112. Right malar bone . . . . . . .112 113. Right palate bone . . . . . . . 113 114. Perpendicular plate of palate bone ..... 114 115. Right inferior turbinated bone ..... 115 116. Vomer . . . . . . . . .117 117. Inferior maxilla ....... 118 118. Front view of skull ....... 122 119. Cerebral surface of base of skull ..... 124 120. Basilar surface of base of skull ..... 126 121. Longitudinal section of nasal fossae ..... 130 122. Os hyoides ........ 131 123. Anterior view of thorax ...... 132 124. Vertebral extremity of seventh rib ..... 134 125. First rib of left side ....... 135 126. Clavicle of right side ....... 137 127. Anterior surface of scapula ...... 138 128. Posterior view of scapula ...... 139 129. Front of humerus ....... 141 130. Back of humerus ....... 141 131. Radius and ulna, front view ...... 143 132. Radius and ulna, back view . . . . . . 144 133. Grooves on back of radius and ulna ..... 146 134. Dorsal surface of carpus ...... 148 135. Bones of carpus of right hand ..... 149 136. Anterior view of hand ....... 150 137. Os innominatum of right side ..... 154 138. Female pelvis ......... 158 139. Diagram to show inclination of pelvis . . Holden 159 140. Anterior aspect of femur ...... 161 141. Diagram of under surface of condyles of femur . Wagstaffe 162 142. Patella of right side ....... 163 143. Tibia and fibula, front view ...... 164 144. Tibia and fibula, back view ...... 165 145. Dorsal surface of left foot ...... 168 146. Plantar surface of left foot ...... T70 147. Anterior ligament of vertebrae, and ligaments of ribs . . 182 148. Posterior ligament of vertebral bodies .... 182 149. Section of an intervertebral disc .... Frey 183 150. Lamina of vertebrae and ligamenta subflava .... 184 151. Anterior view of ligaments of atlas, axis, and occipital bone . 185 152. Posterior view of ligaments of atlas, axis, and occipital bone . 185 153. Occipito-axial ligament ...... 186 154. Transverse and odontoid ligaments ..... 187 XV xvi LIST OF ILLUSTRATIONS. FIGS. PAGE 155. External view of ligaments of lower jaw .... 188 156. Internal view of ligaments of lower jaw .... 189 157. Section through temporo-maxillary articulation . . . 189 158. Vertebra and heads of ribs, showing costo-transverse ligaments . 191 159. Ligaments of spines, laminae, and transverse processes of vertebrae 191 160. Ligaments of pelvis and hip-joint seen from the front . . 194 161. Ligaments of pelvis and hip-joint seen from behind . . 195 162. Ligaments of pelvis and hip-joint seen from behind Bonamy and Beau 196 163. Sterno-clavicular articulation...... 198 164. Ligaments of scapula and shoulder-joint .... 199 165. Sectional view of shoulder-joint . . Alien Thomson 201 166. Ligaments of elbow-joint, inner side ..... 203 167. Ligaments of elbow-joint, outer side ..... 203 168. Upper part of ulna, and orbicular ligament .... 205 169. Lower end of radius and ulna, with articular surfaces . . 205 170. Anterior aspect of wrist-joiut .... Sappey 206 171. Diagram of synovial cavities of wrist-joint . Allen Thomson 208 172. Lateral and anterior ligaments of fingers . . . Reeves 210 173. Anterior view of the ligaments of the knee-joint . . Sappey 214 174. Posterior view of the ligaments of the knee-joint . .Sappey 215 175. Internal view of knee-joint ...... 216 176. Synovial membrane of knee-joint ..... 217 177. Posterior view of ankle-joint ...... 219 178. Ligaments of inner side of ankle and foot . . . Sappey 220 179. Ligaments of outer side of ankle and foot . . . Sappey 221 180. Ligaments of sole of foot .... .Sappey 223 181. Synovial membranes of the tarsal joints . Allen Thomson 224 182. Muscles of the head and face...... 230 183. Muscles of the eyeball ...... 235 184. Orbital contents and capsule of Tenon . Modified from Hcnle 237 185. Muscles of the nose ....... 239 186. Pterygoid muscles ....... 246 187. Deep cervical fascia ....... 248 188. Muscles of front of neck ...... 250 189. Styloid muscles and muscles of tongue .... 255 190. Extrinsic and intrinsic muscles of tongue . . Kolliker 257 191. Dissection of constrictor muscles of pharynx . . Heath 259 192. Side view of muscles of pharynx ..... 260 193. Muscles of soft palate. ..... Heath 263 194. Pruevertebral muscles ....... 266 195. Lateral view of praevertebral muscles .... 267 196. First, second, and part of third layer of dorsal muscles . . 270 197. Fourth, fifth, and part of sixth layer of dorsal muscles . . 276 198. Muscles of occipital region ..... Heath 278 199. Levatores costarum and intercostal muscles Allen Thomson 283 200. Muscles of front of trunk ...... 285 201. Section showing fasciae of groin . . . G. Buchanan 286 202. Aponeurosis of external oblique and external abdominal ring Luschka 287 203. Lateral view of abdominal muscles ..... 290 204. Transverse section of abdominal walls . . Cunningham 292 205. Internal view of abdominal wall in inguinal region . . Wood 293 206. Dissection of inguinal canal . . . . . Wood 294 207. Common scrotal hernia . . . J. T. Gray 296 208. Congenital hernia . . . . . J. T. Gray 296 209. Infantile hernia . . . . . J. T. Gray 296 LIST OF ILLUSTRATIONS. XVII FIGS. PAGE 210. Encysted hernia . . . . H. E. Clark 297 211. Upper surface of diaphragm ...... 299 212. Under surface of diaphragm ...... 300 213. Triangular ligament of urethra ..... 304 214. Diagrammatic view of anterior layer of triangular ligament A. M‘Alister 305 215. Muscles of male perineum ...... 306 216. View of compressor urethra? .... Santorini 307 217. Muscles of female perineum . . . Heath after Savage 309 218. Mode of exposing lateral aspect of pelvic fascia D. J. Cunningham 311 219. Diagram showing arrangement of pelvic fascia . A. M'Atister 312 220. Transverse section of pelvis, showing pelvic fascia . . . 313 221. Diagram of the layers of pelvic fascia . . G. Buchanan 314 222. Transverse section of pelvis, showing pelvic fascia . . Heath 314 223. Scapular muscles, vessels, and nerves . . . Heath 322 224. Muscles of the front of the upper arm . Bonamy and Beau 324 225. Muscles of back of upper arm ..... 326 226. Superficial layer of muscles of forearm .... 328 227. Insertion of flexor tendons, interossei, and lumbricales 11. Quain 329 228. Deep layer of muscle of forearm ..... 330 229. Varieties in arrangement of synovial sheaths at wrist H. A. Reeves 331 230. Superficial muscles of back of forearm .... 333 231. Deep muscles of back of forearm ..... 336 232. Insertion of the muscles of the thumb Heath after Duchenne 338 233. Deep muscles of palm of hand ..... 340 234. Attachment of an interosseous muscle Heath after Duchenne 341 235. Crural sheath laid open .... John Wood 344 236. Structures passing beneath crural arch .... 345 237. Deep muscles of gluteal region ..... 349 238. Muscles of the anterior femoral region .... 353 239 Adductor muscles ..... Sappey 359 240. Muscles of the posterior femoral region .... 362 241. Muscles of the anterior tibial region .... 364 242. Insertion of extensors of toes . . . Duchenne 365 243. Superficial muscles of the back of the leg .... 366 244. Deep muscles of posterior tibial region . . . . 368 245. Parts behind inner malleolus . Hirschfeld and LeveUle 369 246. Dorsal interosseous muscles of foot ..... 371 247. Muscles of sole of foot—first.layer ..... 373 248. ,, „ ,, deep layer . . . Sappey 374 249. Plantar interosseous muscles ...... 376 250. Heart and great vessels . . . Bonamy and Beau 379 251. Carotid arteries and branches of the external carotid . . 384 242. Lingual artery and branches . . Hirschfeld and Reveille 383 253. Internal maxillary artery and branches . . Holden 390 254. Distribution of the ophthalmic artery . Merkel and Henle 395 255. Circle of Willis ....... 401 256. Branches of the subclavian artery ..... 404 257. Axillary and brachial arteries ..... 407 258. Arteries of the forearm . . . . • • 4I3 259. Abdominal aorta and inferior vena cava . . . Henle 420 260. Branches of the cceliac axis ..... Henle 421 261. Course and distribution of superior mesenteric artery . . 423 262. Branches of inferior mesenteric artery .... 425 263. External and internal iliac arteries ..... 428 264. Origin of obturator artery from deep epigastric . . Wood 429 265. Arteries of the perineum ...... 431 xviii LIST OF ILLUSTRATIONS. FIGS. ' _ _ PAGE 266. Gluteal and ischiatic arteries ..... Henle 433 267. Femoral artery and its branches ..... 436 268. Scheme of the profunda femoris artery . . A. M‘Alister 439 269. Popliteal space ...... Heath 440 270. Anterior tibial and dorsalis pedis arteries .... 442 271. Popliteal and posterior tibial arteries .... 446 272. Arteries of sole of foot ...... 447 273. Superficial veins of the head and neck . . . Quain 450 274. Veins of the diploe ..... Wagstaffe 452 275. Sinuses of the upper and back part of skull .... 455 276. Sinuses of the base of the skull ..... 456 277. Cavernous sinus, and artery and nerves on its wall . Longer 456 278. Diagram of the nerves passing through cavernous sinus . Heath 457 279. Veins of the forearm and bend of the elbow . . . 461 280. Superficial veins of thigh and inner side of leg . . . 462 281. External saphena vein and its tributaries .... 463 282. Veins of the trunk ..... Cruveilhier 465 283. Vertebral and spinal veins .... Breschet 469 284. Portal vein ........ 472 285. Lymphatic vessels and glands of the head and neck . . 475 286. Lymphatic vessels and glands of the upper extremity . . 476 287. Lymphatic vessels and glands of the lower extremity . . 478 288. Thoracic duct ........ 483 289. Transverse section of half of spinal cord, showing minute structure Alien Thomson 487 290. Diagram of the tracts of the spinal cord . . Gowers 489 291. Transverse section of spinal cord, showing roots of nerves . 490 292. Paths taken by nerve fibres on entering spinal cord E. A. Schafer 490 293. Front view of upper part of cranio-spinal axis . . Ecker 492 294. Medulla and pons from behind . . G. Dancer Thane 493 295. Section of medulla at level of decussation of pyramids Schwalbe 494 296. Section of medulla through olivary body . . Schwalbe 495 297. Section across pons at middle of fourth ventricle Stilling and Schwalbe 496 298. Base of the brain . . . Hirschfeld and Leveille 498 299. Lateral view of brain of Bush-woman . . Marshall 500 300. Upper surface of brain of Bush-woman . . Marshall 500 301. Inner and under surface of the brain Hirschfeld and LeveilU 504 302. Structure of cortex of hemispheres . . . Meynert 506 303. Centrum ovale majus ....... 507 304. Lateral ventricles of the brain ..... 509 305. Section through hippocamus, showing facia dentata Sappey 511 306. Vertical longitudinal section of the brain Hirschfeld and LeveilU 512 307. Third ventricle of the brain . . Hirschfeld and LeveilU 515 308. Upper surface of the cerebellum . Hirschfeld and LeveilU 516 309. Nuclear masses in white centre of cerebellum . Schtvalbe 518 310. Structure of the cerebellar cortex . . . Meynert 519 311. Fourth ventricle of the brain . Hirschfeld and LeveilU 519 312. Diagrammatic view of floor of fourth ventricle . E. A. Schafer 520 313. Nerve nuclei in floor of fourth ventricle . . . Erb 521 314. Transverse section of cerebrum . . . H. E. Clark 522 315. Transverse section through crura cerebri Wernicke and Gowers 523 316. Relations of brain to exterior of skull . . Poirier 528 317. Side view of sinuses and membranes of brain Hirschfeld and LevedU 531 318. Spinal cord and its membranes . Hirschfeld and LeveilU 534 319. Transverse section of spinal cord and its membranes Hirschfeld and Leveille 535 LIST OF ILLUSTRATIONS. xix FIGS. PAGE 320. Olfactory nerve ....... 537 321. Dissection of the nerves of the orbit Hirschfeld and LeveilU 540 322. Diagram of the fifth nerve and its branches . . . 541 323. Nerves of the orbit ..... Arnold 542 324. Inferior maxillary nerve . . Hirschfeld and LeveilU 544 325. Nerves of the face and scalp . . Hirschfeld and LeveilU 550 326. Nerves of head and neck, right side . Hirschfeld and LeveilU 552 327. Nerves of head and neck, left side . Hirschfeld and LeveilU 554 328. Diagram of the origin and distribution of the ninth, tenth, and eleventh nerves ....... 557 329. Diagram of the connections of the ninth, tenth, and eleventh nerves Hirschfeld and LeveilU 559 330. Nerves of the tongue ....... 561 331. Spinal cord, membranes, and spinal nerves .... 563 332. Roots of the spinal nerves ...... 563 333. Nerves forming brachial plexus .... Lucas 569 334. Nerves of the axilla . . . Hirschfeld and LeveilU 570 335. Nerves of front of forearm . . Hirschfeld and LeveilU 573 336. Nerves of back of forearm . . Hirschfeld and LeveilU 576 337. Nerves of the abdominal wall . Hirschfeld and LeveilU 580 338. Lumbar plexus . . . Hirschfeld and LeveilU 582 339. Diagram of lumbar and sacral plexuses .... 584 340. Nerves of the thigh . . . Hirschfeld and LeveilU 586 341. Nerves of the pelvis . . . Hirschfeld and LeveilU 589 342. Nerves of the back of the thigh . Hirschfeld and LeveilU 592 343. Superficial nerves of back of leg . Hirschfeld and LeveilU 594 344. Dissection of sole of foot . . Hirschfeld and LeveilU 595 345. Cranial ganglia of the sympathetic ..... 598 346. Dissection showing otic ganglion . Hirschfeld and LeveilU 601 347. Scheme of formation of cardiac plexuses . Henry E. Clark 605 348. Diagram of the thoracic sympathetic chain . Henry E. Clark 607 349. Cartilages of nose . . . . . . .612 350. Side view of cartilages of nose . . . Arnold 613 351. Mucous membrane of olfactory region . . . Ecker 614 352. Olfactory cells ..... Schultze 615 353. Appendages of the eye ...... 6x6 354. Meibomian glands ..... Arnold 617 355- Vertical section of upper eyelid . . . Waldeyer 618 356. General diagram of the eye . . . Allen Thomson 622 357. Vertical section of cornea .... Bowman 623 358. Veins of the choroid ..... Arnold 624 359. Iris and ciliary processes ...... 625 360. Ophthalmoscopic view of fundus of eye . . E. Jaeger 626 361. Section through ciliary processes and iris . Iwanoff 627 362. Cells of the pars ciliaris retince . . . Kolliker 628 363. Section of the eye at entrance of optic nerve . . Ecker 628 364. Rods and cones seen from outer surface . . Kolliker 628 365. Pigmentary cells of retina . . . . M. Schultze 629 366. Structure of the retina .... M. Schultze 630 367. Section through yellow spot of retina . . Cardiat 631 368. Crystalline lens ..... Babuchin 632 369. External ear ...... Politzer 634 370. Pinna and its muscles, front view . . . Arnold 635 371. Pinna and its muscles from behind . . . Arnold 636 372. Yiew of the middle ear .... Politzer 637 373. Profile view of left tympanic cavity . . . E. A. Schafer 639 374. Small bones of the tympanum ..... 640 XX LIST OF ILLUSTRATIONS. FIGS. PAGE 375. Vertical section of cochlea of a calf . . Kolliker 645 376. Membranous labyrinth .... Cleland 646 377. Osseous and membranous labyrinth . . . Breschet 647 378. Section through one of the coils of cochlea . . . Henle 648 379. Organ of Corti. ..... Cardiat 651 380. Tongue and tonsils ..... Sappey 653 381. Filiform papillae ..... Kolliker 654 382. Taste-buds from rabbit .... Engelntann 655 383. Upper opening of thorax ..... Heath 658 384. Diagram of heart and circulation ..... 661 385. Right side of heart ....... 662 386. Auriculo-ventricular and aortic valves . Allen Thomson 664 387. Left side of heart ....... 666 388. Section of heart at level of valves .... Sibson 667 389. Position of heart in relation to chest walls . . Lusehka 669 390. Endothelium of the endocardium . . . Kolliker 671 391. Foetal circulation ..... Cleland 673 392. Cartilages of larynx ..... Lusehka 676 393. Arytenoid cartilage ..... Lusehka 676 394. Vertical section of larynx ...... 678 395. Posterior view of larynx .... Sappey 680 396. Side view of larynx . . . . Sappey 681 397. Vertical section of larynx, showing ligaments . Sappey 682 398. Laryngoscopic view of glottis .... Czermak 684 399. Ciliated epithelium of trachea . . . Kolliker 685 400. Structure of thyi’oid body .... Kolliker 686 401. Heart and lungs ....... 689 402. Transverse section of bronchial tube. . . Schidtze 690 403. Intercellular passages of lung ..... 690 404. Lobules of lung, showing air-cells .... Frey 691 405. Capillaries of the lung .... Carpenter 691 406. Capillary network of air-cell ..... Frey 692 407. Transverse section of thorax ..... Heath 694 408. Viscera of the abdomen ...... 696 409. Reflections of the peritoneum ..... 698 410. Transverse section of abdomen, showing peritoneum . Heath 699 411. Median vertical section of nose, mouth, pharynx, &c. . Quain 704 412. Vertical section of tonsil . . . .11. E. Clark 706 4x3. Mucous crypt ...... Kolliker 706 414. Section of submaxillary gland . . . Heidenhain 708 415. Striated epithelial cell from salivary duct . . E. A. Schafer 709 416. Left upper central incisor tooth . . . C. S. Tomes 710 417. Lingual, labial, and distal surfaces of upper canine. C. S. Tomes 710 418. Grinding surface of an upper bicuspid . . C. S. Tomes 711 419. Masticating surface of first upper molar . . C. S. Tomes 711 420. Masticating surface of first lower molar . . C. S. Tomes 711 421. Masticating surface and side view of second lower molar C. S. Tomes 711 422. Vertical section of molar tooth . . . Carpenter 712 423. Section of dentine in the direction of the tubules . Kolliker 713 424. Transverse section of dentine, showing tubules . Kolliker 713 425. Longitudinal section of enamel . . . Kolliker 714 426. Transverse section of enamel .... Kolliker 714 427. Three stages of the development of a tootli-germ . . Frey 716 428. Dentinal sac of a human foetus .... Frey 717 429. Odontoblasts in situ . . . Tomes after MValdeycr 718 430. Normal jaws, showing temporary and permanent teeth C. S. Tomes 719 LIST OF ILLUSTRATIONS. XXI FIGS. PAGE 431. Pharynx laid open from behind ..... 721 432. Transverse section of oesophagus . . . V. Horsley 722 433. Vertical longitudinal section of stomach and duodenum . . 724 434. Diagram of muscular fibres of stomach . . . Henle 725 435. Mucous membrane of stomach ..... 726 436. Section of coats of stomach .... Kolliker 726 437. Compound peptic gland . . . ... Frey 727 438. Gastric mucous glands ..... Frey 727 439. Relations of pancreas and duodenum . Quain after His 728 440. Valvulse conniventes of jejunum .... Henle 730 441. Mucous membrane, showing villi . . . . . 731 442. Section of ileum ..... Kolliker 731 443. Intestinal villus .... Frey after Ley dig 732 444. Brunner’s glands from duodenum .... Frey 733 445. Solitary gland from colon . . . . . 733 446. Surface view of solitary glands .... Ecker 733 447. Vertical section of a Peyer’s patch . . . . Ecker 734 448. Capillaries of mucous membrane . . . Kolliker 734 449. Caecum and ileo-caecal valve ..... Henle 736 450. Upper surface of the liver ...... 74° 451. Under surface of the liver ...... 743 452. Lobules of the liver ....... 745 453. Longitudinal section of two lobules ..... 745 454. Cells of the liver ...... Yeo 746 455. Section of lobule of the liver of a rabbit . . Cardiat 747 436. Arrangement of vascular and biliary capillaries in relation to bile cells . . . . . • • Frey 749 457. Gall bladder and bile ducts . . . .A. M(Alister 751 458. Section of the pancreas of a dog . . . . Klein 752 459. Trabeculae of spleen ..... Cardiat 753 460. Reticulum of splenic pulp .... Cardiat 754 461. Arrangement of splenic corpuscles . . . Kolliker 754 462. Section of Malpighian body of spleen . . Cardiat 755 463. Section of foetal supra-renal body . . Allen Thomson 756 464. Vertical section of supra-renal body .... Eberth 757 465. Section of kidney ....... 759 466. Section of kidney, showing relation of parts . . Henle 759 467. Arrangement of tubules and vessels of kidney Modified from Klein 760 468. Epithelium of uriniferous tubules .... Klein 762 469. Plan of renal circulation .... Bowman 763 470. Transverse section through a Malpighian pyramid . . Frey 763 471. Varieties in arrangement of pelvis of kidney . Gegenbaur 764 472. Side view of male pelvic viscera ..... 768 473. Transverse section of prostate gland . . Allen Thomson 769 474. Bladder and vesicuke seminales ..... 77° 475. Transverse section of penis ..... Heath 772 476. Structure of corpus cavernosum penis . . Langer 774 477. Anatomy of bladder and urethra ..... 775 478. Urethra and neck of bladder ...... 77^ 479. Transverse section of testicle ...... 7%° 480. Diagram of testicle . . . • • • 781 481. Seminal tubules, with developing spermatozoa . Schafer 782 482. Descent of testicle ..... Curling 784 483. Descent of testicle, later stage . . . Curling 784 484. Female pelvic viscera (diagrammatic) .... 785 485. Vertical section of female pelvis in mesial line . . Henle 787 486. Vertical antero-posterior section of uterus . . . Henle 788 XXII LIST OF ILLUSTRATIONS. FIGS. PAGE 487. Uterus and its appendages ...... 789 488. Section of Fallopian tube . . . A. Milroy 791 489. Ovary, showing Graafian vesicles .... Frey 792 490. Minute structure of the ovary and ovum . . Waldeyer 793 491. External organs of generation in the female . . Henle 796 492. Gland vesicles of mammary gland .... Frey 799 LIST OF COLOURED PLATES. PLATE FACES PAGE 1. Occipital bone .... ... 88 2. Frontal bone . . . . . . .92 3. Temporal bone ....... 98 4. Sphenoid bone ....... 102 5. Superior maxillary bone ...... 108 6. Inferior maxillary bone . . . . . .118 7. Clavicle and scapula, dorsal surface . . . 136 8. Clavicle and scapula, ventral surface .... 138 9. Humerus ........ 142 10. Radius and ulna, anterior surface .... 144 11. Radius and ulna, posterior surface .... 146 12. Hand, palmar surface ...... 148 13. Hand, dorsal surface ...... 150 14. Innominate bone ...•••• *56 15. Femur, anterior surface ...... 160 16. Femur, posterior surface ...... 162 17. Tibia and fibula, anterior surface .... 164 18. Tibia and fibula, posterior surface .... 166 19. Foot, dorsal surface ...... 168 20. Foot, plantar surface ...... 172 21. The male perineum .... Maclise 306 22. Arteries of the head and neck . • . Maclise 398 23. Arteries of the hand .... Maclise 414 24. Arteries of the male pelvis . . • Maclise 428 25. Arteries of the foot .... Maclise 446 26. Male perineum ..... Maclise 768 THE ANATOMIST’S VADE MEOUM. PART /. HISTOLOGY The human body, complicated though it be, is made up of a small number of elementary tissues; these by their different combina- tions form the several organs, and a knowledge of them is there- fore essential to the proper understanding of those organs and their uses. The textures of the body which will be described in this section of the work are as follows :—Cells, blood and lymph corpuscles, epithelium, areolar tissue, fibrous tissue, adipose tissue, pigment, cartilage, bone, muscle, nerve, blood-vessels, lymphatic vessels and glands, serous and synovial membranes, mucous membrane, and secreting glands. Some of these are simple in their constitution, and by their combination form the more complex,—such are the cells and fibrous tissues; others are composed of many different con- stituents, arranged often in a very complex manner, and among these are included the blood-vessels, lymphatics, and secreting glands. The latter are here described because it is necessary to consider them apart from the several organs in which they are found, and because it is convenient to speak of them in connection with the more elementary tissues of which they are constructed. Every tissue in the body in its earliest condition consists of an aggregation of minute solid particles which have received the name of cells. Some of the tissues retain throughout life the cellular character, but these are few in number, the majority only having their origin from cells indicated by the presence of minute remains CELLS AND PROTOPLASM. 2 CELLS AND PROTOPLASM. called nuclei. Cells are for the most part spheroidal m shape, unless modified by pressure or other causes, when they may be- come oval, fusiform, scaly, or hexagonal ; in pig- ment, connective tissue, and the nervous centres they are stellate, having ramifying processes which communicate with each other so as to form a net- work. Besides those contained in the tissues there are also free cells floating in the fluid of blood, lymph, and chyle, and one form of them has the power of leaving these fluids and travelling through the tissues; these, the “white corpusclesof the blood, have hence been termed “ wander cells.” Each cell consists of an albuminoid material, transparent, colourless, and of a jelly-like consistence, called protoplasm. The cell may have a distinct bound- ing membrane or cell-tvall, but this is not in- variably the case with the cells of animal tissues ; it has usually one or more central spots called nuclei, within which again are one or two smaller spots called nucleoli; but both nucleus and nucle- olus may be absent without interfering with the vitality of the cell. Protoplasm has commonly a granular appearance, and this is generally due to the existence of a very fine network of fibrils with slight nodes at the points where they intersect (intercellular network). The network is known as the reticulum or sponyio- plasm, while the substance occupying its meshes is called the hyaloplasm. Protoplasm is a proteid substance, similar to albumen ; it has a strong affinity for staining fluids, especially for carmine and hamiatoxylin, consists very largely of water, but is not mis- cible with that fluid, and is weakly alkaline or neutral in reaction. It possesses remarkable vital properties, the chief of which are, (a) its power of motion, (b) its active, nutrition, and (c) the production of similar masses oi protoplasm by division. The powei of motion of protoplasm is exhibited in three ways:—(i.) In changing its shape and position, bv putting out irregular processes (pseudopodia), and then drawing the general mass onwards to the position they occupy ; this is known as amoeboid motion, and In it the protoplasmic mass is able to travel from j'lace to place. (2. The second form of motion consists of streaming movements in the substance of the protoplasm (whether it be stationary or ex hibit amseboid movements), and in the pseudopodial processes o Fig. i. — Different kinds of cells with nuclei and proto- plasm. Fig. 2.—Diagram of aoell with two nuclei, allowing intercellular and internuclear network. KARYOKINESIS. 3 amaeboid protoplasm. (3.) The protoplasm is able to wrap itself around a foreign particle of matter with which it is brought in con- tact, and again to withdraw from it: this is called a movement of in- tussusception. The nutrition of protoplasm consists in its taking up material from without and converting it into substance like itself ; upon this selective and constructive power depends the development and growth of all organised bodies, whether animal or vegetable. The nucleus consists of a small spherical or oval body embedded in the protoplasm, and generally surrounded by a definite mem- brane. The nuclear substance is divisible into a nuclear fluid and a nucleoplasm or nuclear network. The fluid does not take on stain readily, and hence has been named achromatin, while the network, from its affinity for the stain, has been called chromatin or cliromo- plasm. The nuclear network sometimes contains one or more granules or globules, called nucleoli, situated at the intersections of the fibres. The multiplication of protoplasmic masses, or cell-multiplica- tion, takes place by direct or indirect division. Direct Division, or Karyostenosis, consists in the division of the nucleus without any changes taking place in its structure, followed by the division of the protoplasm. This was formerly supposed to be the | common mode of cell - division, but recent investigation shows that neither in animal nor vege- table cells is direct cell-division common. Indirect Division, or Karyokinesis, or Mitosis, is a process wherein the division of the cell is preceded by a series of complex changes in the nuclear network. These, briefly stated, are as fol- lows :— (1.) The nucleus becomes enlarged, and the chromo- plasm, which in the rest- ing nucleus forms a net- work, becomes converted into a number of fine fila- ments, and these become convoluted so as to form a “ skein” (Fig. 4, h. c.). (2.) A series of fibrils appears in the achromatic part of the nucleus, arranged in the form of a spindle (the achromatic spindle) ; these meet at each pole of the nucleus, and Fig. 3.—Direct cell-division or karyostenosis. a. Fully formed cell. b. Division of nucleus and cell. c. Divi- sion of nucleus and cell substance complete, d. Forma- tion of two new cells. Fig. 4.—Views of various stages of karyokinesis. a. Resting nucleus, b. and c. Varieties of con- volution. d. Wreath or spirem. e. and/. Aster stage, s'. Equatorial division, h. Diaster stage. 4 again diverging, radiate into the protoplasm of the cell. The achromatic spindle appears first at the end of the nucleus towards which the filaments of chromoplasm are directed {'polar end), but from thence it moves and takes up a position in the middle of the nucleus. (3.) The chromatic filaments become shorter and thicker, and are disposed in V-shaped loops radiating from the centre of the achromatic spindle (aster stage, Fig. 4, e. f.) ; the filaments next split in their length into two very fine threads. (4.) The threads of the split chromosomes separate, and the two derived from each primary filament pass along the achromatic fibrils in opposite directions towards the poles of the spindle. As they approach the pole they have a radiate appearance (like a rosette) at each end of the nucleus, and this stage has hence been called the diaster stage (Fig. 4, h.), (5.) As soon as the chromosomes separate in this manner into two groups, one at each pole of the nucleus, the cell protoplasm commences to divide, and thus two cells are formed, which, however, remain for some time intimately connected. (6.) The chromatic filaments in the nucleus of each daughter-cell give off branches ; these become convoluted, and form by their inter-communications the internuclear network of the resting nucleus. Protoplasm undergoes a change at its surface, especially in old cells, being converted into a harder layer constituting the cell-wall ; such cells lose their power of amoeboid movement, and, uniting with other cells, form tissues. Cells are connected with each other either by means of their processes (as above mentioned), by direct union of their walls, or by an intercellular substance. BLOOD. BLOOD. Blood is a rather thick fluid, of a bright red or scarlet colour in the arteries, and of dark purple tint in the veins. It has a salt taste, a slight alkaline reaction, a peculiar faint odour, and a speciiic gravity of 1055. It consists of a colourless, transparent fluid, the liquor sanguinis, and of small solid particles, called corpuscles, floating in the fluid. When drawn from the body, it speedily solidifies or coagulates into a jelly-like substance, called a clot, which as it contracts squeezes out a small quantity of transparent, straw-coloured fluid known as serum. In the process of coagulation a substance called fibrin is formed, which entangles the corpuscles in its meshes, so that the clot is formed of fibrin and corpuscles, and is of red colour. The relation between the constituents of blood in the liquid and coagulated states is shown in the following scheme :— Corpuscles Clot Liquid blood< Fibrin ►Coagulated blood. Liquor sanguinis Serum The blood corpuscles are of two kinds, red and white, the former greatly exceeding the latter in number. In healthy human blood the proportion of white to red corpuscles varies from i to 1000 to i to 250. According to Yierordt, a cubic millimeter of healthy human blood contains on an average 5,000,000 red corpuscles and 10,000 white ones. The Red Corpuscles are circular, biconcave discs, having a diameter of about °f an iuch, and a thickness of an inch ; they do not possess a nucleus. In diseased conditions, and occasionally in health, there are also found smaller red corpuscles, about one-third the si/e of the ordinary ones, and spheroidal in shape. The cor- puscles are elastic, and conse- quently change their shape when subject to compression. When the blood is drawn from the vessels, they tend to aggre- gate together and cohere by their broad surfaces, so as to form columns like piles {rou- leaux) of coins. Their shape also varies according to the specific gravity and chemical composition of the fluid in which they are placed. The red corpuscles consist of a tough, elastic, transparent stroma, sup- porting a red crystallisable substance called !Hemoglobin (C600 H9WlX154 FeS30179), which has a strong affinity for oxygen, and can be separated from the corpuscles by certain simple processes in the form of rhombic crystals. The White Corpuscles are larger than the red ones, having a dia- meter of 2suo °f au i]lch > when at rest, they are spherical and have a granular appearance, but they have power of changing their shape, and putting out processes in the manner above de- scribed as amse- boid motion. They are trans- parent masses of protoplasm, and possess one or more nuclei, have no cell-wall, and frequently con- tain granules, or minute masses of red colouring matter. Sometimes they also contain clear spaces or vacuoles. Having the power of passing through the walls of the blood-vessels and travelling from place to place, they are found in the tissues, and are there described BLOOD. Fig. 5.—Blood corpuscles. 1. Bed corpuscle, seen from surface. 2. Red corpuscle, seen from the edge. 3. A group of red cor- puscles adherent by their surfaces, and forming a rouleau. 4. Three-quarter face- 5. Slightly crenated. 6, 7. Crenated corpus- cles. 8. Spherical. 9. Large white corpuscle. 10. Granular leucocyte. 11. Hasmatoblasts. Fig. 6.—White corpuscles of the blood undergoing amseboid changes. 6 LYMPH AND CHYLE. as migrator>/ or wander cells. The white corpuscles are by some observers regarded as an early stage of the red corpuscles. In addition to the red and white corpuscles of the blood, other solid particles have been described under the name of hcematoblasts by Hayern, and of blood-platelets by Bizzozero. They are found in the midst of the interlacing threads of fibrin in clot, after washing away the corpuscles, as minute, round, colourless, disc-like particles, gene- rally aggregated into masses. They have also been observed in the living blood in the smaller vessels of the rat’s mesentery ; their exact nature is uncertain. The Liquor Sanguinis, or Plasma of the blood, is composed of serum, and of two fibrin-factors which unite when the blood is drawn from the body to form fibrin, and thus determine the coagulation of the blood. The serum is the liquor sanguinis deprived of its fibrin ; it has a specific gravity of 1.027, alkaline in reaction, and contains albumen, salts, fatty matter, gases, and sugar. Fibrin is formed by the union of two fibrin-factors, called fibrino- plastin and fibrinogen. Fibrinoplastin, or paraglobulin, is in part contained in the white corpuscles, and in part held in solution in the liquor sanguinis ; it can be precipitated from the liquor san- guinis, in the form of a white powder, by diluting that fluid with ten times its bulk of ice-cold water, and then passing a stream of CO., through it. Fibrinogen is held in solution in the liquor san- guinis, and can be also thrown down as a white powder by a more copious dilution, and a more complete saturation writh C02 than is requisite to precipitate fibrinoplastin. The combination of these factors is brought about by means of a third substance called the fibrin-ferment. Fibrin can be obtained from fresh blood by whipping it with twigs, as fine fibrils of a pale straw-colour, which are in- soluble in water, alcohol, or ether. Gases of the Blood.—The blood contains a very large volume of gases, partly in combination, partly free. These are Carbonic Acid, Nitrogen, and Oxygen. They diifer in their proportion in arterial and venous blood, as shown in the following table :— Oxygen. Carbonic Acid. Nitrogen. Vols. Vols. Vols. Arterial blood . 16 30 1 to 2 Venous blood . 6 to io 35 I to 2 The oxygen is for the most part in loose combination with the haemoglobin of the red corpuscles ; the carbonic acid is in com- bination with the salts of the serum, especially with the salts of sodium ; the nitrogen is suspended in the liquor sanguinis. LYMPH AND CHYLE. Lymph is a nearly colourless, transparent fluid, contained in a special system of vessels called lymphatics or absorbents. The lym- phatics of the small intestine carry, during digestion, a milky fluid EPITHELIUM. named chyle, which consists of lymph mixed with the products of digestion ; but during fasting, these vessels carry transparent lymph, the same as lymphatic vessels elsewhere. Lymph consists of a fluid portion, or lymph-plasma, and corpuscles, lymph corpuscles, floating in it. The plasma resembles liquor san- guinis, and contains about five per cent, of albumen and one per cent, of salts. The corpuscles are indistinguishable from the white corpuscles of the blood, being nucleated masses of protoplasm having the power of amseboid movement; they are most numerous in the lymph after it has passed through the lymphatic glands. Chyle consists also of a fluid, containing corpuscles identical with those of lymph ; but it also has what is called a molecular basis, con- sisting of minute particles of fat with some oil vesicles ; it is this which gives the milky appearance. Both lymph and chyle resemble blood in spontaneously coagulating when removed from the body, forming a thin pale clot, from which serum exudes. EPITHELIUM. The epithelial tissues are distinguished by their retaining the cellular character throughout the whole of life ; they are used chiefly for the purpose of protection, but epithelial cells constitute also the secreting cells of mucous membrane and of glands. The superficial part of the skin consists of many superimposed layers of epithelial cells, constituting the epidermis; those cells on the surface become flattened and dried, and are cast off as thin scales. Besides forming the epidermis, epithelial cells are found covering the surface of the mucous membranes of the alimentary canal, lachrymal, nasal, and respiratory passages, the urinary and genital canals, the ventricles of the brain, and central canal of the spinal cord, also, lining the glandular recesses and ducts of secreting glands. Modified epithelial cells form the terminal nervous ap- paratus of the organs of special sense, such as the eye, ear, and nose. A single layer of flattened epithelial cells covers the surface of the serous membranes of the abdomen, thorax, and cerebro-spinal cavity, and the synovial membrane of joints ; it also lines the heart, blood-vessels, and lymphatics, and the anterior chamber of the eye. In these situations the epithelial tissue is formed from the mesoblastic layer of the embryo, whereas the epithelium elsewhere is derived from the epiblast or hypoblast; for this reason it has been the custom of late years to make a separate class for such tissues, under the name of endothelium. True epithelial tissue consists of one or more layers of nucleated cells, united together by an intercellular cement substance, and resting on a basement membrane, and is divisible into simple non- stratijied and stratified epithelium. Its varieties are the follow- ing :— EPITHELIUM. 1. Squamous. 2. Columnar. 3. Glandular. 4. Transitional. 5. Ciliated. 1. Squamous, Scaly, or Tesselated Epithelium is so called be- cause the cells appear as thin flattened scales ; they frequently have in their centre a small nucleus and nu- cleolus, which are of soft consistence ; the rest of the cell is more dense. In the surface cells of the epidermis the nu- cleus and nucleolus disappear, the cells being converted into thin plates of horny consistence. On the skin, the mucous membrane of the oral cavity, lower half of pharynx, oesophagus, nasal duct, tympanic cavity, vagina, female urethra, bladder, ureter, pelvis of the kidney, and on the conjunctiva of the eye they form the surface layer of a thick mass of cells, the deeper constituents of which are commonly spheroidal or fusiform in shape. The scales are somewhat larger in the mouth and fauces than elsewhere, and in longest diameter measure to 7(ln of an inch ; in the vagina between and ; and on the skin ?S<*)(T. The nucleus, which is round or oval in shape and flattened, measures in scales from the mouth of an inch. In the deep layers of a stratified epithelium, and especially in the rete mucomm of the skin, there are found numerous cells with fine fibres or spikes projecting from their edges ; they are called prickle-cells. The processes of neighbouring cells are joined in such a manner as to leave little canals or intercellular channels between them. 2. Columnar or Cylinder Epithelium consists of cells which have an elongated or pyriform shape, their bases being directed to the free surface, and their apices to the basement membrane to which they are attached. They are ranged side by side like columns, and are con- nected together by a small amount of intercellular or cement sub- stance. Each column contains near its middle a nucleus, which gives it a swollen appearance, and the nucleus possesses one or more nucleoli; from the transparency of the column the nucleus may be seen through its base. This form of epithelium is found in the alimentary canal from the cardiac end of the stomach to the anus, in the intestinal glands, in the mammary and lachrymal glands, in Fig. 7.—Old epithelium cells from the mouth. Fig. 8.—-Prickle cells from rete ntucomm. Fig. 9.—Portion of col- umnar epithelium from one of the villi of the small intestines. 1. Nu- cleus of the cell. 2. Basement membrane. EPITHELIUM. the male urethra, vas deferens, seminal vesicles, Cowper’s glands, glands of Bartholine, and uterine glands. Many of the cells have projecting processes on their edges, by which they are connected with similar pro- cesses in neighbouring cells, the in- terstices left between the processes being filled in hv lymphoid or other small cells. The protoplasm both of the cell and nucleus appears granular, this appearance being due to the presence of an intercellular and internuclear network. Such cells often have vacuoles in their substance ; others contain fatty globules or mucin. The mucin frequently distends the cell so much as to push the nucleus towards the attached end of the cell, and by still further distention bursts the cell, leaving a hollow cavity at the free extremity ; such cells are then called goblet or chalice cells. Columnar cells, especially those in the mucous membrane of the intes- tine, have an appearance of fine vertical striation at the free edge ; these striae are probably minute rods or columns, and the part of the cell containing them is sometimes separated off from the rest of the protoplasm by a transverse line or plate. In the cells of the smaller salivary ducts, and in some of those lining the uriniferous tubes of the kidney, it is the attached border, and not the free one, which is striated. 3. Spheroidal or Glandular Epithelium is composed of cells which are spheroidal in shape, but often become more or less polyhedral from compression. This form of epithelium occurs in secreting glands such as the liver and pancreas, the salivary, gastric, and intestinal glands, and the glands of the skin. They appear granular owing to the presence of a fine reticulum in the cell and nucleus, and generally contain the materials which the gland • secretes. 4- Transitional Epithelium is the early form of all the varieties Fig. io.—Columnar epithelium from the small intestine. Separate cells showing nucleus and nucleolus. Fig. ii.—Appearance of the surface formed by the apposition of the bases of several cells. Fig. 12.—Goblet-cells from the epi- thelium of an intestinal villus from the human subject, treated with Muller’s fluid (Schulze), a. Goblet- cells. 6. Cylinder-cells. Fig. 13.-Saccule of a sebaceous gland.a.Gland cells clothing the walls, b. Those which have been cast off, filled with oil globules, and occupying the lumen of the sac. EPITHELIUM. of epithelium, and generally has the character of small granulai spheroidal cells. In the pelvis of the kidney, ureter, urinary bladder, and urethra, however, the transitional epithelium is peculiar, con- sisting of three or four layers of cells. The surface cells are smooth on their upper surface, but hollowed underneath into pits which receive the rounded ends of pear-shaped cells situated beneath them ; between the narrow necks of the pear-shaped cells there are smaller cells, rounded or irregular in shape. 5- Ciliated Epithelium is characterised by the presence of minute conical vibratile filaments or cilia mounted on the broad ends of columnar cells, or upon the free surface of those of the spheroidal kind. The cilia are in constant action, and produce a wave-like motion, which carries the secretions in contact with them towards the outlet of the organ in which they exist. They have an average measurement in the human trachea of to irsVc; an inch. Ciliated epithelium is found (1) in the mucous membrane of the lower part of the nasal cavities and the adjoining accessory cavities ; (2) in the nasal duct and lachrymal sac ; (3) the Eustachian tube and cavity of the tympanum; (4) the upper part of the pharynx and upper surface of the soft palate ; (5) the larynx (excepting over the true vocal cords), trachea, bronchi, and bronchial tubes to their smallest branches; (6) the uterus and its glands, and the entire length of the Fallopian tubes ; (7) the vasa efferent!a and coni vasculosi of the testicle ; (8) some part of the ventricles of the brain, and the whole length of the central canal of the spinal cord ; (9) the ducts of the lingual and pharyngeal glands ; (10) in the embryo, lining the oesophagus, over the whole pharynx and part of the mucous membrane of the stomach. Ciliated cells possess an intercellular and internuclear network, Fig. 14.—Cells of the columnar ciliated epi- thelium of the nose, magnified 310 times. Pig. 15.—Various forms of ciliated epithelial cells, from the trachea of a cat. CONNECTIVE TISSUE. 11 and many of them give off forked processes from their deep aspect (fig. 15). ENDOTHELIUM.—It lias been said above that endothelium differs from epithelium in being derived from the mesoblast; another difference is that endothelial cells are never supported by a basement mem- brane. Endothelium consists of flattened cell plates, held together at their edges by a cement substance which becomes stained brown when the surface is painted with a solution of nitrate of silver. The outlines of the cells thus made apparent are commonly irregular or jagged; more especially where the cells line the lymphatic vessels. Although the majority of the cells are thin and fiat, there occur here and there in serous membranes groups of polyhedral or cubical thicker cells, composed of granular protoplasm ; these are supposed to be in a condition of reproductive activity, and hence are described as germinating endo- thelium. Such cells generally border the lymphatic pores or stomata in the serous membranes. Endothelial cells are found lining the cavities of the peritoneum, pleura, pericardium, and aqueous chamber of the eye ; on the surface of the spinal cord and brain ; lining the heart, blood-vessels, and lymphatic vessels ; lastly, on the free sur- face of synovial membranes. Fig. 16.—Endothelium. Showing stomata bordered by germinat- ing cells. Connective tissue forms the means of union between the several tissues and organs, forms coverings for the muscles and sheaths for the vessels, and constitutes the supporting framework for the cellular and other elements which make up the individual organs. It consists of fibres and of cells, the former greatly preponderating, and being easily divisible into two sets, elastic and non-elastic. Having many and various duties to perform, connective tissue is necessarily greatly diversified in its arrangement, differing also in different regions in the proportion of cells to fibres, and of the elastic fibres to the non-elastic. We may, however, readily dis- tinguish three chief forms of connective tissue, each of which requires a separate and complete description ; these are the areolar (including the adipose), the fibrous, and the elastic. Areolar Tissue.—This consists of delicate fibres and transparent laminae crossing each other in all directions, and leaving between them irregular interspaces or meshes, called areolce; these are occupied by a small quantity of clear colourless fluid, sufficient only CONNECTIVE TISSUE. 12 CONNECTIVE TISSUE. to keep the threads and laminae moist. In the midst of the fibres and laminae we can, by the use of reagents, demonstrate the existence of numerous branch- ed and anastomosing cells, the connective tissue corpuscles; they are composed of pro- toplasm, which is in some transparent, in others granular, and they have a clear nucleus, and often one or more nucleoli. The cells lie in a gelatinous semifluid substance (called the ground substance), which joins the fibres of the tissue together, making them into bundles, occupying in it cavities (called “ cell spaces ”) which correspond accurately to the shape and size of each cell. Be- sides the branched cells, there are also found in areolar tissue a number of migratory or wander cells, like the white corpuscles of the blood, composed of protoplasm, and con- taining one or more nuclei. These cells have the power of moving from place to place, and they become especially numerous when the tissue undergoes inflammation. The fibres are very tine, measuring from to 2 °f an i’tch, and are apparently structureless. By means of tlie ground substance they are united into bundles, which have a wavy course, and, when viewed by reflected light, have a white and shining appearance. Mixed with these we commonly find a number of coarser fibres, having a tendency to curl at their ends, and not gathered into bundles ; acetic acid, which causes the bundles of fibres to swell up and become indistinct, has no effect on these single fibres ; they will be more fully described in a later page as yellow or elastic fibres. From the loose arrangement of areolar tissue, it is often subjected during life to infiltration of fluid, this constituting anasarca. Areolar tissue is found beneath the skin, forming a continuous layer all over the body ; beneath serous and mucous membranes ; around muscles, vessels, and nerves, form- ing sheaths for them, and connecting them with neighbouring parts. It is also found connecting and supporting the lobules Fig. 17.—A portion of living connective tissue, cot out from between the muscles of the frog’s thigh (highly magnified), a. A pale contracted cell. 6. Ramified cor- puscles. c. A similar corpuscle with vesicular nucleus. d and e. Motionless, coarsely granular cells, f. Fibrilte. g. Bundles of connective tissue, h. Elastic fibrous net- work. CONNECTIVE TISSUE. 13 of glands, and in the interior of organs supporting their proper tissues. Adipose Tissue, or Fat, may be described as areolar tissue the meshes of which are occupied by vesicles containing oil. It is chiefly found immediately beneath the skin, forming there a con- tinuous layer over nearly the whole surface of the body, the pannicxdus adiposus; it also exists very plentifully in the mesentery and omenta of the abdomen, round the joints, on the surface of the heart, round the kidneys, and entering into the formation of the marrow of bones. It consists of vesicles which measure from j-fa to T) of an inch, filled with oil; they are aggregated together so as to form little masses or lobules, and are contained in the meshes of areolar tissue. A nucleus generally exists at one side of the vesicle, but is commonly obscured by the oily contents ; it is the remains of the protoplasm of the cell from which the vesicle was formed. The vesicles are usually globular in form, unless they have been compressed, when they become hexagonal or polyhedral. After death the contents of the vesicles often crystallise, appearing as groups of fine acicular crystals, which are supposed to consist chiefly of margaric acid. Each lobule of fatty tissue has enter- ing it -a small artery, and leaving it a small vein, these being connected to- gether by a very fine plexus of capil- lary vessels. No adipose tissue is found, in health, in the subcutaneous tissue of the eyelids or penis, nor in the lungs (except near their roots), nor in the cavity of the cranium. Fibrous Tissue.—This tissue forms the periosteum of bones, ligaments to bind the bones together, tendons for the attachment of muscles, strong pro- tecting coats for certain organs, and fasciae to separate the muscles from each other. Thus two forms of it are described—the fascicular, where the fibres are gathered up into bundles so as to form a rounded or flattened band, and membranous, where they are spread out so as to form a thin sheet. It is composed of fine filaments gathered into bundles, and having all the characters and properties of the white fibres described as forming the greater part of areolar tissue. These are either arranged parallel to each other, as in the formation of tendons and ligaments, or they spread out, cross, and get inter- Fig. 18.—Areolar and adipose tissue, a,fa. Fat vesicles. b, b. Fibres of areolar tissue. Fig. ic —Fat vesicles from omen- tum, showing nuclei at the margins of the vesicles. CONNECTIVE TISSUE. 14 woven, so as to form a membranous sheet, as in fasciae and sheaths of muscles. In the fascicular form white fibres exist almost exclusively ; in the membranous form there is a slight admixture of yellow elastic fibres. When a tendon is treated with acetic acid, the white fibres of which it is composed swell up and become transparent; there are then brought into view chains of oblong flat- tened cells lying between the tissue bundles ; these are nucleated, the nuclei of pairs of adjoining cells lying side by side. By the use of reagents it can be shown that these cells lie in cell spaces similar to those already described as lodging the cells of areolar tissue; the cell spaces accurately correspond in size and shape to the cells which they lodge. Although the cells appear cubical in longitudinal view, transverse sections of the tendon show them to be stellate, giving off nume- rous fine processes, which penetrate between contigu- ous bundles of the tendon. Fibrous tissue is white and glistening; it is very strong, but is inelastic, un- less when intermixed with yellow fibres. It, is con- verted into gelatine by boiling. Yellow Fibrous Tissue, or Elastic Tissue, enters very generally into the structure of 1 issues and orgains in which the property of elasticity is an important quality. As an elastic and binding element it is present in the common areolar tissue and superficial fascia, in the fascial sheaths of muscles, in tin* fibrous capsules of different organs, as of the spleen, in the corium of the skin, in serous and mucous membranes, in the coats of blood-vessels and ducts ; and, in certain situations, is the sole tissue present, as in the ligamenta subflava, vocal cords, thyroepiglottic ligament, crico-thyroid membrane, lateral thyro-hyoid and stylo-hyoid liga- ments, the membranous layers connecting the cartilaginous rings of the trachea and bronchial tubes, and ligamentum susponsorium penis. It is most easily obtained from the ligamentum nucliae o' the ox, sheep, or horse. Fig. 20.—White or non-elastic fibrous tissue. Fro. 21.—Caudal tendon of a young rat, showing the arrangement and form of the tendon cells. CONNECTIVE TISSUE 15 The fibres of elastic tissue ai’e cylindrical or flattened, brittle, colourless when single, but yellowish in an aggregated form, elastic, admitting of being stretched to double their length and returning to their original size, and variable in dimensions, ranging from to I , of an inch in length, and from to ,r±al) in breadth. The nucleus is oval, and sometimes so elongated as to deserve the name of columnar; it contains an elaborate network of very fine fibrils and often one or more nucleoli. The body of the cell is granular, and presents traces of longitudinal striation ; it has a fine sheath, probably elastic, and containing transverse linear thickenings, which here and there give the fibre a varicose appearance. The transverse lines are most distinct when the cell is contracted (Klein). The fusi- form cells are united into little bundles or fasciculi by an adhesive interstitial substance, and the fas- ciculi, which are sometimes round and sometimes flat, are bound to- gether into larger bundles by are- olar tissue and fine elastic fibres; the interspaces of the bundles being occupied by vessels and nerves, the former in great abundance. The fasciculi are connected by their ends with fine tendinous fibres, by means of which they become attached to neighbouring parts. Unstriped muscle is distributed abundantly in the animal frame, and is met with in the alimentary canal, from the middle of the oesophagus to the internal sphincter ani ; in the posterior part of the trachea, and in the bronchial tubes to their finest ramifications; in the excretory ducts of various glands, as Wharton’s duct, the common bile duct, the calices and pelvis of the kidneys ; in the capsule and trabeculae of the spleen, the ureters, bladder, and urethra ; in the vasa deferentia and vesiculae seminales, the prostate, Cowper’s glands, and in the substance of the corpora cavernosa ; in the Fallopian tubes, uterus, and vagina ; in the deep layer of the mucous membrane of the alimentary canal (muscularis mucosce) ; in the middle coat of arteries, veins, and lymphatic vessels; m the iris and ciliary muscle ; and in the corium of the skin, particularly in the areola and nipples of the mammary glands, in the dartos of the scrotum, and around the hair follicles, and many of the sudoriferous and sebaceous ducts. The muscular structure of the heart presents certain peculiari- ties which distinguish it both from the striated and non-striated forms, although the presence of transverse markings leads to its being Pig. 45.—Anastomosing muscular fibres of heart. On the right the cells and nuclei are seen. NERVE TISSUE. classed with the former. The strife are more faintly marked than those of ordinary striped muscle, and the fibres are smaller, and have no sarcolemma ; they are remarkable for their numerous branches and frequent anastomoses, and are formed by the union of distinct cells joined end to end. Each cell has a single nucleus near its centre and one or two nucleoli ; they frequently contain small fatty granules which are greatly multiplied in fatty degenera- tion of the heart. NERVE TISSUE. The nervous system consists of nerve centres and of rounded oi flattened cords, called nerves, which connect the centres with each other, and bring them into relation with the surface of the body, the muscles, and the different organs. The brain and spinal cord constitute the great nervous centre, or cerebro-spinal axis, and the great majority of the nerves spring from this centre or are connected with it. There also exists a secondary system oi nerves called sympathetic, the cen- tres of which occur in the form of numerous minute masses named (janglia, which are distributed chiefly in the thorax and abdo- men, and are intimately connected with the nerves going to the organs contained in those cavities. The sympathetic and cerebro-spinal nerves have frequent communica- tions with each other, which form complicated networks or plexuses. The nerve tissues are readily separable into two forms, the white and the grey; the former consti- tutes the greater portion of the interior of the brain, the outer part of the spinal cord, and al the nerves which spring froir these ; the latter exists in the in- terior of the spinal cord, on the surface of the brain, in the in- terior of the brain near its base, and in the sympathetic and cere- bro-spinal ganglia. The structural elements of the nervous system Flu. 46.—Nerve fibres of various kinds. a. Showing the axis cylinder and pri- mitive sheath, b. Another, with axis cylinder, after treatment with bichro- mate of potash, c. A fibre, treated with collodium, showing the axis cylinder, primitive sheath, and nodes of ltanvier. d. A non-medullated fibre, showing the axis cylinder and primitive sheath. e.A non-medullated fibre from the olfactory of the calf. /, g, h. Fine fibres from the brain with axis cylinders. The fibre g unites with the process of a ganglion cell by the branch marked *. NERVE FIBRES. are also of two kinds, nerve fibres and nerve cells. The fibres form the channels of com- munication between the centres and the organs, and when gathered together into bundles form nerves ; the cells are restricted in their distribution to the nerve centres, ganglia, and certain of the organs of sense. NERVE FIBRES are of two kinds—white or medullated, and grey or non-medullated. The white or medullated nerve fibres form the white matter of the brain, spinal cord, and nerves. When examined imme- diately after removal from the body they seem to be structureless, and are bounded by a wavy outline. In a short time, however, their appearance changes, and they come to present a double boundary line ; the fibre now consists of three parts, an outer delicate, transparent covering, a central thread, firm and solid in consistence, and between these a substance which has a wavy or irregular margin, and often a nodulated aspect. The outer layer is called the 'primitive sheath or neurolemma; it is so fine and transparent as to be difficult of demonstration, and, indeed, it is only when a break takes place in the substance of the fibre that it becomes visible; it is elastic and apparently structureless. The primitive sheath disappears when nerves enter the substance of the brain or spinal cord, and is also absent from many nerves in their peripheral distribution. Beneath the primitive sheath at wide intervals are small nucleated masses of proto- plasm ; they are the nerve corpuscles; they correspond to the nuclei found beneath the sarcolemma of muscle, but are much less numerous. The pulpy substance which lies between the primitive sheath and the central thread is called the medullary sheath (white matter of Schwann). It is viscous, clear, transparent, and easily susceptible of coagulation, and is converted in its coagulated state into an opaque, granular, white substance. It is found to consist to a large extent of fatty matter, and, after nerves have been some time removed from the body, becomes ir- regular in outline, its margins become Fig. 47.—Medullated nerve fibre, a. Axis cylinder. Medullary sheath. «. Nucleus, p. Granular pro- toplasm around nucleus. r. Node of Ranvier. i, i. Dissepiments in medul- lary sheath. 34 NERVE FIBRES. wrinkled, and portions of it assume the form of round or irregular nodules ; these changes are presumably the result of a kind of coagulation. The centre of the fibre is formed by a firmer and more homogeneous band called the axis cylinder. It is elastic, greyish in colour, has a very faint and indistinct boundary line, and is generally flattened or oval in transverse section ; it is about one-third the thickness of the nerve fibre. It often presents traces of longitudinal striation, and may occasionally be split up into fine filaments, this taking place especially at the commencement and termination of a nerve ; these filaments have been regarded by some observers as the ultimate structural elements of the nerve, and have hence been called primitive fibrillce. Each axis cylinder is continuous with one of the poles of a ganglionic cell. It is distinguished from the other parts of the nerve fibre by its becoming deeply coloured, when a thin section of fresh nervous matter is placed in a solution of carminate of ammonia, while the primitive sheath becomes only faintly tinged, and the medullary sheath is totally unaffected by the reagent. The axis cylinder has also a great affinity for gold salts, becoming stained violet-black when placed in solutions of them ; when treated with nitrate of silver and exposed to light it shows transverse striae, these being most marked near to the nodes of Ranvier ; they are known as Frommann's lines. Nodes of Ranvier.—Medidlated nerve fibres present breaks in the continuity of their structure at intervals of about jk of an inch. At these points the axis cylinder is continued uninterruptedly ; the primitive sheath also passes over the breaks, but as the fibre is here smaller than elsewhere, the sheath is drawn inwards towards its centre. The medullary sheath is, however, completely interrupted, terminating by a rounded edge. The primitive sheath is separated from the axis cylinder by a small quantity of material of an albu- minous character, and corresponding in its behaviour with reagents to the intercellular substance which we have spoken of, as cementing together neighbouring cells. These breaks in the nerve fibre have been named from their discoverer the Nodes of Ranvier. Non-medullated or Gelatinous Nerve Fibres {fibres of Hemal-) are found in the great nerve centres as continuations of the medul- lated fibres ; they also constitute the greater number of the fibres of the sympathetic, and the whole of the olfactory nerves in man. In the brain and spinal cord, they are connected with the processes of the multipolar nerve cells, and serve to connect the medullated fibres with those cells. They are pale in colour, flattened, and bounded by single contour lines; they measure from soYm t() srYm of an inch in diameter. In structure they are found to consist of a transparent, apparently homogeneous sheath corresponding to the primitive sheath of the medullated til ires, beneath which are numerous oval nuclei. The interior of the fibre consists of a substance corresponding in every particular to the axis cylinder of medullated fibres, and made up of bundles of exceedingly fine primitive fibrillae. Non-medullated fibres may thus he regarded as medullated tibi'es devoid of a medullarv sheath. NERVE CELLS.—These are found in the grey matter of the brain and spinal cord, and in the cerebro-spinal and sympathetic ganglia. They are of various shapes and sizes. Some in the grey matter of the cortex of the brain, in the posterior horn of the grey centre of the spinal cord, and in certain ganglia, are spheroidal, and of very small size. The majority of the nerve cells are, however, distinguished by possessing processes or “poles” by means of which they become connected with each other, and with the nerve fibres passing into the grey centres. A few of the cells possess only one process, and are called unipolar, others have two processes, and are called bipolar, but the greater number have many processes which branch and form elaborate connections with neighbouring cells and nerve fibres ; they are named multipolar cells. Many of the nerve cells found in the surface grey matter of the brain are triangular in shape, having their bases directed towards the centre of the brain, and their apices towards the free surface; from their angles they give off NERVE CELLS. 35 Fig. 48.—Gelatinous nerve fibres from olfactory nerve. Fig. 49.—Multipolar cells from the anterior grey column of the spinal cord of the dog-fish (a) lying in a texture of fibrils ; (6) prolongation from cells; (c) nerve-fibres cut across. tine processes. Nerve cells vary in size from -iho °f ai1 inch in width ; they have each one or more clear transparent nuclei, in the centre of each of which a nucleolus is visible.. 36 NERVE CELLS. The cell protoplasm is often granular, of a light brown or greyish colour, and presents traces of striation, such as we noticed in the axis cylinder of medullated nerve fibres ; not unfrequently it con- tains deposits of brown pigment. No distinct limiting membrane or cell wall has been ascertained to exist, but each cell is lodged in a kind of capsule composed of fine connective; tissue, and lined by a delicate layer of flattened epithelial cells. The cell processes are composed of protoplasm of the same nature as the cell itself; they also present traces of fibrillation, and are likewise destitute Fig. so.—Multipolar ganglion cells from tlie brain, i. A cell, one of whose processes (o') becomes the axis cylinder of a nerve fibre (b). 2. A cell (a) connected with another (6) by means of a commissure (c). 3. Diagram of three cells (a) connected by means of commissures (6), and running into fibres (c). 4. A multipolar cell containing black pigment. of a limiting membrane. One or more processes of each nerve cell may be traced into a nerve fibre, becoming continuous with the axis cylinder of the fibre ; other processes become continuous with the “poles” of neighbouring cells. From the fact that nerve cells were first, discovered in ganglia, they are often called “ganglion cells the true ganglion cell, however, differs from the cells above described, in respect that the primitive sheath of the nerve fre- quently is continued as a covering over the cell, and in some NERVE GANGLIA. 37 instances the medullary sheath also may be traced as a thin coating over its exterior. Neuroglia.—The proper substance of the nervous centres (nerve fibres and nerve cells) is supported by a peculiar modification of connective tissue, described by Virchow under the name of neuroglia. This bears a close resemblance to the reticular tissue, described on a previous page, consisting of a reticulum formed by the intercom- munication of processes of greatly branched cells. Besides this, there exists a finely granular matrix, in which the nerve cells are embedded. GANGLIA.—In its widest signification a ganglion is a nervous centre, whether found in the interior of the brain or spinal cord, or existing in an isolated posi- tion, remote from those great aggregations of nerve matter ; in a more restricted sense it is limited to those small secondary centres found in large numbers throughout the sympathetic system in con- nection with the roots of the spinal nerves, and on the trunks, or connected with some of the branches of the cerebral nerves. Ganglia have a fibrous covering, continuous with the sheath of the nerves entering and leaving them ; from tliis capsule processes are sent into the interior of the ganglion, dividing it into compartments. The interior of the ganglion is of a greyish colour, and consists of nerve cells and nerve fibres, sup- ported by connective tissue. The nerve cells are round, oval, or multipolar, and are covered by a continuation of the primitive sheath of the nerves, and sometimes also by the medullary sheath. Some of the nerve fibres pass through the ganglion without becoming connected with the cells, [others terminate in the branches of the multipolar cells, their axis cylinder becoming continuous with the protoplasm of the cell pro- cess. Large pyriform ganglion cells are occasionally found in the sympathetic system; every ganglion cell of this kind is connected with at least two nerve fibres, one of which is straight, and passes directly to the centre of the cell ; the other winds spirally round the first, and is traceable for some distance on the outer surface of the bell. According to Arnold the central fibre is connected with the Fig. 51.—Sketch of a sympathetic ganglion. a, b, c. Nerve trunks, d. Multipolar cells. d’. Axis cylinder of nerve joining pole of cell, c, unipolar, and/, apolar cells. 38 NERVES nucleus of the cell and the spiral fibre with the nucleolus. The two fibres on leaving the cell run in opposite directions in the nerve with which the gang- lion is connected. A commissure is a col- lection of nerve fibres act- ing as a link of communi- cation between two nerve centres. A nerve is a rounded or flattened cord of nerve fibres which forms the channel of connection between the nerve centres and all the parts oi the body. The nerve cords are surrounded by a strong sheath of fibrous membrane called epineurium, which no only preserves their roundel form, but forms septa which pass into the interior of the cord, subdividing it into number of strands or funiculi. Each funiculus is also surroundei by a membrane called perineurium, composed of fine connective tissue arranged in concentric lamellae, with lymph clefts be- tween them; in the surface layers, there is a preponderance of elastic tissue. The lamellae an lined on both their surfaces by single layer of flattened epitheiia cells. The nerve fibres in each funiculus are held together by very fine connective-tissue fibres, forming the endoneurium ; these run longitudinally, and serve to support the blood-vessels distri- buted to the nerve. Branching of Nerves.—A branch of a nerve consists o several funiculi which leave the parent trunk and become in- vested with an epineurium de- rived from its sheath. Inosculation or Communi- cation.—Nerves frequently form junctions of a portion of their substance so as to become complex in structure, but in such cases the individual nerve fibres do not as a rule communicate with Fig. 52.—Structure of ganglionic nerve cell. a. According to Beale, b. According to Arnold, a. Central fibre, b. Spiral fibre. c. Capsule of ganglion. Fm. 53- —Section of a small nerve, i. Perineurium. 2. Lymph space beneath perineurium. 3. Lymph space pene- trating into centre of nerve. 4. E11- doneurium. 5. Nerve fibres cut across. 6. Nuclei of endoneurium. each other, but remain separated by their medullary and primitive sheaths. In the nervous centres, however, in the peripheral dis- tribution of the nerves, and, in rare instances, in their trunks, the libres themselves branch and form communications, so as to pro- duce a true anastomosis. Nerve tubules by their medullary sheath are insulated throughout their whole course. Plexus.—A plexus is an intricate intercommunication between the funiculi of adjacent nerves. Origin.—The apparent origin of a nerve is where it becomes connected with the surface of a nerve centre. The real origin is where its fibres terminate in the substance of its nerve centre— often far away from where it plunges into the nerve surface. It is very difficult to trace accurately the deeper connections of the ex- tremities of nerve fibres, but as in many instances they have been observed to be directly connected with multipolar cells, the opinion is becoming general that all nerve fibres have a central connection with a nerve cell. NERVE TERMINATIONS—Nerve fibres, whether of the medul- lated or non-medullated variety, when they approach their termi- nation, freely branch, and form numerous communications among themselves, the medullated fibres lose their medullary sheath, and become indistinguishable from the non-medullated kind. The axis cylinder takes part in the branching of the fibres, and becomes split up into very fine threads, consisting of only a few elementary fibrils. The primitive sheath is continued as a covering to the divided fibres, for some distance after they have lost their medullary sheath, but at length becomes also lost; and the fine pale fibrils which form the termination of the nerve may then be traced as faint 1 ines having a wavy course, and marked at short intervals by irregular varicosities. Sensory or afferent nerves and motor or efferent nerves have very different modes of termination, and require therefore a separate description. Sensory Nerve Endings.—Sensory nerves terminate either in epithelial cells, as in the cornea and skin, or by special terminal organs, some of which fall to be described here, while others will come under consideration in the description of the organs of sense to which they belong. We shall in this place speak only of the Pacinian corpuscles, and the end bulbs of Krause, leaving the rods and cones of the retina, the cells of Gorti and acoustic filaments of the internal ear, the taste buds of the tongue, the olfactory cells of the nose, and the tactile corpuscles of the skin to be discussed in the description of the organs in which they are found. The Pacinian or Vater’s Corpuscles are small oval or pyriform masses, varying in size from half a line to three lines in length, situated on the peripheral extremities of the nerve fibres, chiefly in the palm of the hand and sole of the foot, but also found in other parts, as the penis and clitoris, bulb of the urethra, on the intercostal nerves, branches of the sacral plexus, on the cutaneous nerves of the NERVE TERMINATIONS. 39 40 NERVE TERMINATIONS. neck, arm, and leg, and dorsum of the hand and foot, infraorbital nerve, and on the nerves of the periosteum, nipple, and mamma, and those distributed to joints. It has been calculated that in the palm of the hand and palmar surface of the fingers there are six hundred of these bodies, and at the extremities of the fingers they are especially numerous. They are situated for the most part in the subcutaneous areolar tissue, are clear, transparent, and glistening in appearance, and traversed internally with white streaks. In struc- ture a Pacinian body is composed of from twenty to sixty concentric Fig. 54.—Portion of a digital nerve, showing the dis- position of the Pacinian corpus- cles. Fig. ss-—Pacinian corpuscle from the mesentery of a cat. a. A nerve forming the stalk. 6. The system of capsules, c. Axial canal or internal bulb, within which the axis cylinder ends forked. layers or capsules of areolar tissue, separated by spaces containing lymph, and having a central cavity also filled with lymph which contains the free extremity of a nerve fibre, divested of its sheath and medulla and reduced to the condition of an axis cylinder. The intercapsular spaces are wider between the external than the internal layers, and each capsule is lined by a single layer of squamous epithelial cells ; neighbouring capsules are often branched and connected with each other by fibres. The central stalk of the corpuscle consists of the medullated nerve fibre entering it, and the sheath of the nerve may be traced into the outer layers of the capsule. The axis cylinder included within the central cavity ends NERVE TERMINATIONS. 41 in a small rounded tubercle, and not unfrequently is bifid or even trifid. The end bulbs of Krause have been ascertained to exist in the sclerotic conjunctiva, the mucous membrane of the floor of the mouth, the soft palate and tongue, the lips, and in the skin of the glans penis and glans clitoridis. They are usually spheroidal or oval in shape, and measure about 600 of an inch in diameter. They con- sist of a capsule of connective tissue containing a soft substance which is transparent and apparently granular, and has embedded in it numerous oval nuclei. A niedul- lated nerve fibre enters its under surface, and as it passes in, generally loses its medullary sheath ; the axis cylinder may be traced into the cen- tral matrix, where it terminates by dividing into two or more branches. They thus closely resemble the Pa- cinian corpuscles. The end bulbs which pass to the genital organs (litter in some respects from those just described, and have been named yenital nerve corpuscles; they are characterised by the existence of numerous constrictions which give them a mulberry-like appearance. Motor Nerve Endings. — Of these there are two varieties; namely, those passing to striated muscle, and those distributed to the non-striated. The former have received the name of motorial end plates. The nerves passing to a voluntary muscle retain their medullary sheath, and primi- tive sheath, till they reach the sar- colemma, when the former ceases, and the latter becomes continuous with the sarcolemma. The axis cylinder pierces the sarcolemma and expands beneath it, so as to pro- duce a prominence (nerve eminence), often divided into lobes, and containing many clear oval nuclei. In unstriped or involuntary muscle the nerve fibres are arranged in very fine plexuses over the surface of the muscle cells, and some histologists state that the terminal filaments can be traced into the nucleus or nucleolus of the cell. SYMPATHETIC NERVE.—The sympathetic or ganglionic nerve, or system of organic nerves, has received its various designations from its numberless communications and anastomoses, from its com- Fig. 56.—End bulbs. 1. From the con- junctiva of a calf. 2. From that of a human being, a. Bulb. c. Nerve fibre ending in an axis cylinder (6). 42 position of a series of ganglia, and from its distribution chiefly to the viscera of the body. It consists of a cord of moderate thickness, which extends from tile head to the coccyx, lying by the side of the vertebral column ; of a series of ganglia, some of which are fusiform and others flattened and multangular ; of short branches of communi- cation from the spinal nerves ; and of peripheral branches, which for the most part follow the trunks of arteries, and are distributed to the viscera, after uniting with ganglia in their course, or forming smaller ganglia in their distribution. The elementary constituents of the ganglionic nerve are: medullated nerve fibres of every degree of magnitude from coarse to tine, non-medullated or ganglionic nerves, and nerve cells. The medullated nerve fibres are derived from the anterior and posterior roots of the spinal nerves, chiefly from the latter ; entering the ganglion, they divide into an ascending and descending fasciculus, which pass upwards and downwards along the main trunk of the nerve, or pass off with the larger branches in company with ganglionic nerves. The non-medullated fibres originate in the multipolar cells of the sympathetic ganglia. In their peripheral terminations the branches of the sympathetic nerve present numerous minute, almost microscopic ganglia, which are especially remarkable on the carotid arteries, in the pharyngeal plexus, upon the heart, around the root and in the substance of the lungs, upon the supra-renal capsule, on the lymphatic glands, on the posterior wall of the urinary bladder, and in the kidneys. In structure these ganglia are identical witli the larger ganglia. BLOOD-VESSELS. BLOOD-VESSELS. The blood is distributed throughout the body by means of a series of tubes, which proceed from the heart, ramify through all the organs and tissues, and again return to the heart ; thus the blood in its course constantly returns to the centre from whence it was sent forth, and it is this which constitutes the circulation. The tubes which carry the blood are called blood-vessels ; they are of three kinds— namely, those which convey the blood from the heart to the tissues, arteries ; those which run through the tissues and organs, capil- laries ; and those by means of which the blood is returned from the tissues to the heart, veins. The artery proceeding from the left ventricle of the heart contains the pure or arterial blood, which is distributed throughout the entire system, and constitutes with its returning veins the greater or sys- temic circulation. That which emanates from the right ventricle conveys the impure blood to the lungs ; and with its corresponding veins establishes the lesser or pulmonary circulation. ARTERIES. 43 ARTERIES. The arteries are the cylindrical tubes which convey the blood from the ventricles of the heart to every part of the body. They art' dense in structure, and preserve for the most part the cylindrical form when emptied of their blood, which is their condition after death : hence they were considered by the ancients as the vessels for the transmission of the vital spirits, and were therefore named arteries (dr/p Tijpe'iv, to contain air). The whole of the arteries of the systemic circulation proceed from a single trunk, named the aorta, from which they are given off as branches, and divide and subdivide to their ultimate ramifications, constituting the great arterial tree which pervades by its minute subdivisions every part of the animal frame. From the aorta the branches for the most part pass off at right angles, as if for the purpose of checking the impetus with which the blood would other- wise rush along their cylinders from the main trunk ; but in the limbs a very different arrangement exists ; the branches are given off from the principal artery at an acute angle, so that no impedi- ment may be offered to the free circulation of the blood. The division of arteries is usually dichotomous, as of the aorta into the tw'o common iliacs, common carotid into the external and internal, &c. ; but in some few instances a short trunk divides suddenly into several branches which proceed in different directions : this mode of division is termed axis, as the thyroid and cceliac axis. In the division of an artery into two branches, it is observed that the combined area of the two branches is somewhat greater than that of the single trunk ; and if the combined area of all the branches at the periphery of the body were compared with that of the aorta, it would be seen that the blood, in passing from the aorta into the numerous distributing branches, was flowing through a conical space, of which the apex might be represented by the aorta, and the base by the surface of the body. The advantage of this provision in facilitating the circulation is sufficiently obvious ; for the increased channel which is thus provided for the current of the blood, serves to compensate for the retarding influence of friction, resulting from the distance of the heart and the division of the vessels. The main arteries of the limbs run on the flexor aspect, as they are in that situation less liable to external injury or to over-stretching in the movement of the joints, than if placed on the extensor aspect. Communications between arteries are free and numerous, and increase in frequency with the diminution in size of the branches ; so that, through the medium of the minute ramifications, the entire body may be considered as one uninterrupted circle of inosculations or anastomoses (civa, between, aropa, mouth). This increase in the frequency of anastomosis in the smaller branches is a provision for counteracting the greater liability to impediment existing in them 44 STRUCTURE OF ARTERIES. than in the larger branches. Where freedom of circulation is of vital importance, this communication of the arteries is very remark- able, as in the circle of Willis in the cranium. It is also strikingly seen in situations where obstruction is most likely to occur, as in the distribution to the alimentary canal, around joints, or in the hand and foot. Upon this free communication existing everywhere between arterial branches is founded the principle of cure by the ligature of large arteries ; the ramifications of the branches given off from the artery above the ligature inosculate with those which pro- ceed from the trunk of the vessel below the ligature ; these anas- tomosing branches enlarge and constitute a collateral circulation, in which several large branches perform the office of the single obliterated trunk. Arteries pursue a fairly straight course, but in some parts they are tortuous ; this is the case in the arteries of the lips and uterus, and in those passing up to the base of the brain. In some instances the tortuous course is to permit of free motion of the parts crossed by the vessel; in others it appears to have the effect of diminishing the force of the propulsion of the blood. Structure of Arteries. —Arteries are composed of three coats, external, middle, and internal. The external coat (tunica adventitia) is firm and strong; it is thin in the large arteries, but thicker than the middle coat in arteries of small and medium size, and is composed of white fibrous and elastic tissue. The white fibres are arranged in close bundles, which run for the most part dia- gonally or obliquely across the vessel ; they form by their inter - comm unica- tion a firm felted mem- brane, with minute in- terspaces, in which lie numerous branched connective-tissue corpuscles. Among the white fibres a few elastic fibres are found ; these are most numerous in the inner layers (that is to say, near the middle coat), and are arranged longitudinally. The interlacement of the fibres is closest in the inner layers, and becomes looser as we approach Fig. 57.—A small artery. At b, the homogeneous internal layer; c, middle tunic formed of un- striped muscular fibre ; d, the external connec- tive-tissue tunic. STRUCTURE OF ARTERIES. 45 the outer surface of the vessel. Longitudinal bands of unstriped muscular fibre have been described as existing in the outer coat of many of the larger arteries, such as the splenic, renal, mesenteric, axillary, popliteal, and femoral. The middle coat (tunica media) is in all arteries the thickest and most important. It is composed of many layers of unstriped muscular fibres, with, in the larger arteries, the addition of elastic tissue, and a small quantity of white fibrous tissue ; these structures are almost entirely arranged transversely. This coat is very brittle, and hence is easily cut through when a ligature is applied. The unstriped mus- cular tissue is almost the only component structure of the middle coat of small arteries ; in which there are two or three laminae, the fibres, about of an inch in diameter, and to .,})V) of an inch long, being arranged in rings ; in smaller arteries there is but one muscular lamina, the elements of the fibres being shorter, and in proportion as the arteries are more minute, becoming reduced to the earliest developmental form—namely, short elliptic cells with oblong nuclei ; ultimately they are completely lost. The elastic tissue is absent altogether in the middle coat of small arteries, but makes its appearance in arteries of medium size as fine fibres disposed in a network of wide meshes. In the larger kind of medium-sized arteries, the elastic network is mingled with areolar -tissue, and a tendency to the alterna- tion of these tissues begins to be apparent. While thus encroaching as it were on the structure of the middle coat of arteries, the elastic tissue presents a corresponding series of transitional forms ; at first it exists as fine fibres disposed singly or in a fine network with open meshes ; then the fibres become larger and the meshes closer, and interlaced so as to form a fibrous membrane with narrow meshes; next, by the in- crease of breadth of their fibres and their intimate union or fusion, a homogeneous membrane is formed, in which the meshes appear as simple perforations (fenestrated membrane). In medium-sized arteries the elastic tissue forms a single layer lying external to the Pro. 58. — Smooth muscular fibre cells from the middle coat of the artery. 1. From the popli- teal. 2. From a twig of the ante- rior tibial, half a line in diameter. a,a,a. Elongated or rod-like nuc- leus. The middle cell (marked 6) has been ren- dered transpa- rent by immer- sion in vinegar. Fig. 59. — Elastic mem- brane of the fene- strated kind, from the middle coat of the carotid artery of a horse. 46 STRUCTURE OF ARTERIES muscular fibres; in the largest arteries of this class it is mingled with areolar tissue, and exhibits a tendency to become laminated, the laminae alternating with similar layers of areolar tissue. In the large arteries this is the common character of the middle coat ; the elastic tissue is laminated, and between the laminae are strata of areolar and muscular tissue. The presence of elastic tissue as a chief constituent of the middle coat of large arteries gives them Pig. 6o.—Transverse section of wall of posterior tibial artery, a. Endo- thelial lining of tunica intima. b. Elastic layer of tunica intima. c. Tunica media, d. Tunica adventitia. (E. A. Schafer.) a yellow colour, while those arteries m which the muscular tissue is abundant have a reddish tint. In the aorta, the laminae of the middle coat are forty or fifty in number. The internal coat (t-unca intima) is the thinnest of the three, and easily broken in the transverse direction ; it is composed of three layers, an internal layer or endothelium, a subendothelial layer, and an external elastic membrane, which is either homogeneous or made up of elastic elements, disposed in a longitudinal direction. The in- ternal endothelial layer is formed by a single layer of flattened cells, very thin, polygonal or elliptical in shape, and having transparent oval nuclei; their outlines can be made evident by pencilling the inner surface of the artery with a solution of nitrate of silver. The subendothelial layer is absent from the smallest arteries, hut is distinguishable in all those of medium and large size in the form of longitudinal bundles of fibrous connective tissue, between which are numerous anastomosing branched connective- tissue cells. The elastic layer is a thin, homo- geneous membrane of the fenestrated kind, perforated with minute oblong openings having a direction parallel with the axis of the vessel. It is thrown into longitudinal folds when the vessel is empty, and becomes extremely delicate, and is finally lost in the minute vessels. Exteriorly this layer assumes a reticulated char- acter, and is made up of a longitudinal network of elastic fibres. Fio. 61.—Endothelium lining an artery. CAPILLARIES. In taking a summary survey of the constituent tissues of the three coats of arteries in their order of succession from without inwards, it will he seen that the external coat consists of areolar and elastic tissue ; the middle coat of smooth muscular fibre, areolar and elastic tissue ; and the internal coat of elastic tissue and endothelium. The arteries in their distribution through the body are included in a loose areolo-fibrous investment which separates them from sur- rounding tissues, and is called a sheath. Around the principal vessels the sheath is an important structure ; it is composed of areolar tissue, intermingled with aponeurotic fibres, and is continuous with the fasciae of the region in which the arteries are situated, as with the thoracic and cervical fascia in the neck, transversalis and iliac fascia, fascia lata in the thigh, &c. The sheath of the arteries contains also their accompanying veins, and sometimes a nerve. The coats of arteries are supplied with blood like other organs of the body ; their vessels proceed from the neighbouring small branches, and are named vasa vasorum. The vasa vasorum or vasa nutritia ai’e distributed in the external coat, some few making their way among the external layers of the middle coat. They are met with even on the smallest arteries, and form a rich capillary network with rounded meshes. The small veins which return the blood from the capillaries, open into the companion veins of the artery. The nerves, like the vasa vasorum, are found only in the external coat, and are wanting altogether in many arteries, as in those of the cerebral and spinal substance, the choroid membrane of the ovum, the placenta, and also in the arteries of some muscles, glands, and membranes. Lymphatic vessels and lymph spaces are present in the outer coat. 47 CAPILLARIES Tlie arteries do not terminate directly in veins, but in an inter- mediate system of vessels which, from their minute size (about J H) of an inch in diameter), are termed capillaries (capillus, a hair). The capillaries constitute a microscopic network, which is distributed through nearly every part of the body, so as to render it impossible to introduce the smallest needle-point beneath the skin without wounding several of these fine vessels. It is through the medium of the capillaries that all the phenomena of nutrition and secretion are performed. They are remarkable for their uniformity of diameter, and for the constant divisions and communications which take place between them, without any alteration of size. They communicate on the one hand with the terminal branches of the arteries, and on the other with the minute radicles of the veins. In the maternal part of the placenta and in the erectile organs (as the corpus caver- nosum penis), the arteries empty into lacunar spaces, from which the veins gather up the blood, without the intervention of capillaries ; and an arrangement somewhat similar is also found in the spleen. jSucquet and Hover assert that in some parts the small arteries pass 48 STRUCTURE OF CAPILLARIES. directly into small veins, so that the blood does not enter the capil- lary system. Structure of Capillaries.—The capillaries are the smallest and simplest of the blood-vessels, their wall being formed by a single layer of flattened endothelial cells, the edges of which can be brought into view by pencilling the surface with nitrate of silver. The cells are irregular m shape, being often pointed at their extremities and sinuous at their edges. They are united together by an albuminous cementing substance, and are connected externally with the pro- cesses of the connective-tissue corpuscles of the neighbouring tissues (Klein). During inflammation, the connecting cement of the cells often gives way so as to leave pores or sto'inata, through which the white corpuscles of the blood (and occasionally the red ones) pass In certain parts the capillaries have, in addition to their endothelia lining, an outer coat, formed by a network of branched connective- tissue cells. Although capillaries are, as stated above, remarkable for their uniform size in any particular organ, they differ in this respect in different localities being smallest in the brain and lung, and largest in the marrow of bones; they are small also in muscle and large in skin and mucous membrane. They differ greatly in the size anil arrange- ment of the meshes which they form, and consequently in the amount of blood which they supply to the tis- sues, the network being very close in the lungs and choroid coat of the eve, in most mucous membranes and in glands, and very wide in ligaments, tendons, and similar structures. In muscle, nerve, and tendon the meshes of the capillary jffexiis are long and narrow ; in the lungs, adipose tissue, and secreting'glands they are rounded or polygonal ; while in the skin and mucous mem- branes the capillaries are drawn out into long loops. Fig. 62. — Transition of a minute artery into capillary vessels—from the brain. 1. Minute artery. 2. Transitional capillary. 3. Coarse capillary with thick coat, represented by a double contour line. 4. Fine capillary, with single contour. The nuclei are seen widely scattered in 4 and 3; more closely congre- gated in 2; and still more so in 1. a. The transverse elongated nuclei of muscular cells; the muscular coat of the artery. VEINS. 49 VEINS. The veins are the vessels which return the blood to the heart, after it has been circulated by the arteries through the various tissues of the body. They are much thinner in structure than the arteries, so that when emptied of their blood they become flattened and collapsed. The veins of the systemic circulation convey the dark-coloured and impure or venous blood from the capillary system to the right auricle of the heart, and they are found after death to be more or less dis- tended with that fluid. The veins of the pulmonary circulation contain during life the pure or arterial blood, which they transmit from the capillaries of the lungs to the left auricle. The veins commence by minute branches which are continuous with the capillaries, and converge to constitute larger and larger branches, till they terminate in the main trunks which convey the venous blood directly to the heart. In diameter they are larger than the arteries, and, like those vessels, their combined areae would con- stitute a hollow cone, whereof the apex is placed at the heart, and the base at the surface of the body. It follows from this arrange- ment, that the blood in returning to the heart is passing from a larger into a smaller channel, and therefore that it increases in rapidity during its course. Veins admit of division into superficial and deep. The Superficial veins return the blood from the integument and superficial structures, and take their course between the layers of the superficial fascia ; they then pierce the deep fascia in the most convenient and protected situations, and terminate in the deep veins. They are unaccompanied by arteries, and are the vessels usually selected for venesection. The Deep veins are situated among the deeper structures of the body, and generally in relation with the arteries ; in the limbs they are enclosed in the same sheath with those vessels, and they return the venous 1 flood from the capillaries of the deep tissues. In com- pany with all the smaller, and also with the secondary arteries, as the brachial, radial, and ulnar in the upper, and the tibial and peroneal in the lower extremity, there are two veins placed one at each side of the artery, and named venue comites. The larger arteries, as the axillary, subclavian, carotid, popliteal, femoral, are accom- panied by a single venous trunk ; and certain veins, such as those of the cranium, spinal canal, liver, and larger veins of bones, run apart from arteries. The communications between veins are more frequent than those of arteries, and they take place between the larger as well as the smaller vessels ; the venae comites communicate with each other in their course by means of short transverse branches which pass across from one to the other. The office of these inosculations is very apparent, as tending to obviate the obstructions to which veins are STRUCTURE OF VEINS. particularly liable from the thinness of their coats, and from their inability to overcome much impediment by the force of their current. Structure of Veins.—Veins closely resemble arteries in their structure, and like them are formed of three coats—external or tunica adventitia, middle or tunica media, and internal or tunica intima. It will be sufficient if we here indicate the particulars in which these several coats differ from those corresponding to them in arteries. External Coat.—This is thick in proportion to the other coats, and is composed of longitudinal and oblique bands of fibrous tissue, with some elastic fibres; the interstices between the fibres lodge ramified connective-tissue corpuscles. In certain veins, as the in- ferior vena cava, renal, azygos, spermatic, and external iliac veins, this coat contains a thin layer of unstriped muscular tissue. Middle Coat.—The transverse muscular fibres which distinguish this coat in both arteries and veins are in the latter very thin ; they never form continuous layers, and are never separated from each other by distinct elastic membranes as in the arteries, the interven- ing substance in veins being usually white fibrous tissue. Inner Coat.—This coat is firmer than the inner coat of arteries, and can be stripped off without breaking ; it consists of an endothelial layer, a subendotlielial layer of branched cells, and an elastic layer, either forming fenestrated membrane, or existing simply as a closely areolated longitudinal network of coarse and tine elastic fibres.! Longitudinal muscular fibres are found in the inner coat of some veins. Variations in the Structure of Veins.—The middle coat is wanting in the thoracic part of the inferior vena cava and in the hepatic veins ; it is most developed in the splenic and portal veins, and in those of the gravid uterus. The superior and inferior vena cava and pulmonary veins as they enter the heart receive a covering of striped muscular fibres, continued on to them from that organ. Muscular tissue is absent from the veins of the maternal part of the placenta, the jugular and subclavian veins, the veins of the retina, the sinuses of the dura mater, the veins of bones and muscle, and the spaces in the substance of the corpora cavernosa of the penis. The veins of the gravid uterus have muscular tissue in considerable quantity, and distributed throughout all three of their coats. The Valves of Veins are composed of a thin stratum of fibrous tissue mingled with tine elastic fibres, and coated on the two surfaces with the endothelial lining of the vessel. The segments or flaps of the valves of veins are semilunar in form, and arranged in pairs, one upon each side of the vessel; in some instances there is but a single flap, which has a spiral direction, and occasionally there art* three. The free border of the valvular flaps is concave, and directed forwards, so that while the current of blood is permitted to flow freely towards the heart, the valves are distended, and the current intercepted, if the stream become retrograde in its course. On the cardiac side of each valve the vein is expanded into two pouches LYMPHATICS. (sinuses), corresponding with the flaps of the valves, which give to the distended or injected vein a knotted appearance. The valves are most numerous in the veins of the extremities, particularly in the deeper veins, and they are generally absent in the very small veins, and in the veins of the viscera, as in the portal and cerebral veins, those of the liver, kidney, and uterus; they are also absent in the large trunks, as in the venue cavue, venue azygos, innominate, pulmonary, and iliac veins. The trunk and branches of the umbilical vein are devoid of valves, as are also the ovarian veins, and the veins of the can- cellous tissue of bone. Sinuses are venous channels, excavated in the structure of an organ, and lined by the internal coat of the veins ; of this structure are the sinuses of the dura mater, whose external covering is the fibrous tissue of the membrane. The external investment of the sinuses of the uterus is the tissue of that organ. Veins, like arteries, are supplied with nutritious vessels, the rasa vasorum; their nervous filaments, few in number and of small size, are derived from the sympathetic and spinal system ; they have been chiefly found on the larger veins, as, the venue cavue, iliacs, crural, jugular, vertebral, and sinuses of the dura mater. Fig. 63.—a. Part of a vein laid open, with two pairs of valves, b. Longitudinal sec- tion of a vein, showing the valves closed. LYMPHATICS. Lymphatic vessels form a secondary vascular system and serve two important purposes, namely, to convey into the blood the products of intestinal digestion, and to return to the blood materials which having been once used do not require to be excreted, but may, after undergoing change or elaboration in the lymphatic vessels and glands, be again used for the building up of tissues. The vessels employed for the first of these purposes are called lacteals, from the milky fluid they convey ; the rest of the vessels are called lymphatics, from the fluid contained being clear and transparent (lympha, water). These two kinds of vessels do not differ structurally from each other. The lymphatic system consists of three parts, vessels, capillaries, and glands. Lymphatic vessels are of two kinds — large vessels, as the thoracic duct and its tributaries ; and small vessels, such as are found throughout the body generally. Both kinds possess a great number of valves placed at very short distances from each other, so that when a lymphatic vessel is inflated it presents a beaded appear- ance. The valves are almost identical in structure and arrangement STRUCTURE OF LYMPHATICS. 52 with those described in connection with veins, consisting of one or two semilunar folds formed by the lining membrane of the vessel. The large vessels correspond in structure to veins, and have three coats of extreme thinness ; the outer formed of delicate fibrous tissue, the middle of unstriped muscular fibres, and the inner of elastic tissue supporting a single layer of nucleated endothelial cells, of elongated form and with sinuous edges. The small lymphatics are very numerous, being found in every part of the body, in every organ, and probably existing in every tissue. They are much more numerous than the veins, but are of microscopic size ; they form, bv their communications, complicated plexuses, the meshes of which are often exceedingly close. Their walls are formed by a single layer of flattened endothelial cells with sinuous edges and nuclei which are not in the centre of the cells ; their tubular shape and the existence of valves serve to distinguish them from the lymphatic capillaries. Lymphatic Capillaries.—These are often larger than the smallest trunks, but are distinguished from them by the extreme irregularity of their shape and by the absence of valves. They vary greatly in their ar- rangement in dif- ferent parts, some- times ensheathing the blood-vessels, at others forming irregular lacunar cavities, or, yet again, enclosing the bundles of fibrous tissue in a tendon, and form- ing for them a delicate sheath. In whatever form they exist, they may be identified by pencilling the tissue with a solution of nitrate of silver, when the endothelial cells are made evident by the colouration of the intercellular cementing substance. The wall is formed by a single layer of cells, which differ from those lining the smallest lymphatic vessels by being shorter, and having more sinuous outlines. Many lymphatic capillaries open into a system of lacunae, con- nected with each other by minute canals (the lymph-canalicular system of Recklinghausen), the lacunae lying in an albuminous ground substance, and lodging ramified cells or connective-tissue corpuscles. The contained cells constitute a sort of lining on one Fig. 64.—Lymphatic capillaries ; showing the great variation in their size and shape. STRUCTURE OF LYMPHATICS. side of the lacuna, and are continuous with the endothelial cells of the lymphatic capillary with which the lacuna is connected. The lymph-canalicular system is almost the only representative of the lymphatics in the cornea, the grey and white matter of the brain and spinal cord, and in cartilage. In tendon, fascia?, muscle of both kinds, and nerves, the lymphatics are found as continuous clefts or longitudinal spaces between the connective-tissue bundles or the proper fibres of the tissue. In areolar tissue they form the areolae or interspaces which we have described on a previous page as characterising that tissue ; and in the nervous centres they form spaces or sheaths around the blood-vessels, which have been named ;perivascular lymph spaces. The lymphatics of serous membranes are very numerous, and have a complicated arrangement which cannot here be fully described ; the most important features are, first, that there are frequent invaginations of the blood-vessels, either by lymphatic tubes or by an intercommunicating system of lymph sinuses lined with endothelium ; and, second, that the lymphatic capillaries communicate with the surface of the serous membrane by means of openings called stomata, which are bordered by ger- minating epithelium differing in character from the cells which form the surface of the membrane. The germinating cells when ripe become detached, and form free lymph cells. ft will be thus seen that there are two chief forms in which the lymphatics originate, namely, by spaces or sinuses lined bv a com- plete endothelium and by irregular lacunae, lined only on one side by a branched connective-tissue cell. Lymphatic Glands (absorbent glands) are small, oval or bean- sliaped, flattened or rounded bodies, of a reddish-brown colour, placed at short intervals in the course of the small lymphatic vessels. They are found in groups in the axilla, popliteal space, groin, lumbar region of the abdomen, round the root of the lungs, and in the neck, and are joined together by means of the lymphatic vessels which enter or leave them. Each gland presents externally the appearance of being com- posed of lobules, and generally has at one side a slight depression or hilus, through which the blood-vessels enter the interior. The lymphatic vessels connected with the gland consist of a large one apparently issuing from the very centre of the gland, called vas efferens, and numerous smaller ones passing into the interior at different parts of the periphery, each of these being called a vas afferens. On section the external part of the gland is found to be of a different colour and consistence to the interior, and hence the two parts are distinguished as cortical and medullary. The gland is surrounded by a capsule which is continuous with the outer coat of the afferent and efferent vessels ; it is formed of white fibrous tissue, the fibres crossing each other in different directions, and enclosing connective-tissue corpuscles in their meshes. At the hilus the fibres of the capsule are continued into the interior of the gland, the fibrous tissue becomes mixed with a small quantity of unstriped 54 STRUCTURE OF LYMPHATICS. muscle, and the bands so constituted radiate from the centre!to the periphery, and become connected with the interior of the capsule ; they thus form numerous septa which divide the cavity of the gland into spaces. In the cortical part of the gland the fibrous trabecula) form thin lamellae, and enclose relatively large oval spaces, called alveoli (Jf) to of an inch wide), which communicate with each other by small openings in the partitions. In the medullary part the trabeculae exist as flattened cords or bands, which form by their communications a network, the meshes of which freely open into each other. The alveoli of the cortical and meshes of the medullarv Fic. 65.—Peritoneum covering the central tendon of the diaphragm of a rabbit. a. Tendon bundle covered by squamous endothelial cells with wavy margins. 0. Endothelium covering space between tendon bundles, cells of small size. c. One of the stomata, surrounded by ger- minating endothelium, d. Sinus of a lymphatic vessel. Fto. 66.—View of a lym- phatic gland, i, i, i. Vasa afferentia. 2. A vas efferens. 3. Body of the gland. part- are occupied by the proper glandular or adenoid tissue, tvhicli in the former takes the shape of oval masses (follicles), and in the latter that, of cords or cylinders (medullary cylinders). In both cortex and medulla the gland pulp or substance is separated from the trabeculae forming alveoli and meshes by a space of nearly uniform width throughout; this is the lymph simis or lymph path. It is not empty, but is occupied by retiform connective tissue, that is to say, ramified or anastomosing cells ; these support large numbers of lymph corpuscles, which are carried onwards by the current of lymph. The lymphoid tissue which forms the great mass of the gland, consists of a reticulum of fine homogeneous fibrils or mem- STRUCTURE OF LYMPHATIC GLANDS. 55 branes, arranged so as to form a honeycomb, and covered by numerous flattened endothelial cells. The reticulum is crowded with lymph Fig. 67.—Section of a small lymphatic gland, half diagrammatically given, with the course of the lymph, a. The capsule. 0. Septa between the alveoli of the cortical portion, c. Septa of the medullary portion, down to the hilus of the organ, d. Adenoid tis- sue. e. Lymph vessels of the medullary mass. /. Different lymphatic streams which surround the follicies, and flow through the interstices of the medullary por- tion. g. Confluence of these passing through the efferent vessel, h, at the hilus of the organ. corpuscles of small size. The lymphoid tissue contains a dense network of capillary blood-vessels. Course of the Lymph. —The afferent vessels, after branching upon and in the tissue of the cap- sule, open into the lymph sinus in the cortex of the gland ; the efferent vessels, on the other hand, commence by small branches connected with the sinus in the medul- lary meshes. The lymph enters the cortical alveoli by the afferent vessels, traverses the lymph path in the cortex, from thence passes into the medulla, and taking its course through the lymph path in that part of the gland, reaches the efferent vessel, and by it leaves the gland. The lymph cells which it receives in such large numbers in passing through the gland are derived from the lymphoid tissue tilling up the great part of the Fig. 68.—Part of medulla of a lymphatic gland. a. Trabecula cut longitudinally. 6. Surface of the trabecula covered by endothelium, c. Lymph sinus, d. Medullary cylinders composed of lym- phoid tissue. 56 cavities in the cortex and medulla. On entering a gland the lym- phatic vessel loses all its coats except the inner endothelial one, which is continued over the trabeculae, forming a delicate lining for these partitions. The lymphatic glands above described are sometimes spoken of as compound lymphatic glands, to distinguish them from masses of lymphoid tissue found in various parts of the body, and described as simple lymphatic glands. Examples of the latter are the tonsils, glands at the root of the tongue, thymus gland, solitary and agminate glands of the intestine, and the Malpighian bodies of the spleen. These will be described in the section on the viscera, in connection with the organs of which the adenoid masses form a part. SEROUS MEMBRANES. SEROUS MEMBRANES. These occur m the form of a tlun transparent web which lines the interior of cavities containing viscera, and is so disposed as to facili- tate movement. The chief examples are the pleurae and pericardium in the chest, peritoneum in the abdomen, arachnoid in the cranium and spinal canal, and the tunica vaginalis in front of the testicle. A serous membrane consists of two parts, one which lines the cavity, called the parietal layer ; the other, which is reflected from the wall of the cavity, and is prolonged over the con- tained organ, the visceral layer. These two layers are in contact on their free sur- faces ; and from this free surface a very small quan- tity of limpid fluid is secreted, which serves the purpose of a lubricating medium, and so facilitates the gliding of the enclosed organ in its cavity. The serous membranes are all closed sacs, retaining their fluid contents when from any cause there is an abnormal effusion. The only exception to this is the peritoneum in the female, where at the extremity of the Fallopian tube the serous membrane is continuous with the mucous lining of the tube. In some cases, as the serous membrane of the heart and lungs, its arrangement is very simple ; in others, as the peritoneum, it is very complex, owing to the number of organs contained in the cavity ; but in all (except the arachnoid) the two layers can easily be made out. At the place where the reflection takes place, the vessels of the contained organ enter it. The viscus, although said to be sur- rounded by the serous membrane, is in reality outside of it. The accompanying plan of such a sac will give an idea of the manner of arrangement. Structure.—Serous membranes are lined bv a laver of flattened Pig. 69. — Plan of a serous membrane. 1. Wall of cavity. 2. Parietal layer of serous membrane. 3. Visceral layer. 4. Vessel entering at tlie reflection. 5. The contained organ. SYNOVIAL MEMBRANES. endothelial cells with sinuous edges and clear oval nuclei, each con- taining one or more nucleoli. Openings exist in many of the serous membranes, which, as stated above, communicate with the lymphatic capillaries ; they are called stomata, are commonly oval in shape, and are bordered by cells which are thicker and of a more granular character than those covering the rest of the surface (see Fig. 16, p. ii). As these cells are actively growing, and often produce free corpuscles, they have been described by Klein under the name of germinating endothelium. Besides the stomata, other interruptions in the epithelial layer have been note d. These are called pseudo-stomata,; they are not true openings, hiit are processes of protoplasm sent up to the surface by the con- nective-tissue cells of the subserous tissue. The deep layer of serous membranes con- sists of a connective-tis- sue ground substance formed of yellow and white fibres, and sup- porting the capillary vessels and lym- phatics ; the ground substance also contains branching connective-tissue cells lying in cell spaces, many of the processes of which pass up between the epi- thelial cells of the surface and form pseudo-stomata. The fluid secreted by serous membranes is almost identical with the fluid part of lymph, and from the fact that the cavities formed by serous membranes freely communicate with the lymphatic system through the medium of the stomata, it is now generally held that they are indeed lymph spaces or sacs. As withdrawn from healthy serous cavities the fluid coagulates spontaneously, but when it accumulates under conditions of disease (in dropsy, for instance), it requires for its coagulation the addition of some substance containing globulin. 57 Fig. 70.—Endothelium from abdominal surface of cen- tral tendon of diaphragm of a rabbit, stained with nitrate of silver, a. Large endothelial cells covering the general surface of the membrane. 6. Smaller cells over a lymphatic capillary, in which several pseudo-stomata may be seen. SYNOVIAL MEMBRANES. These membranes are nearly identical in structure with the serous membranes, but the secretion is more viscid and something like the white of egg, whence the name. They line the cavities of joints, and are interposed between tendons and bones when much friction or pressure is produced during their movements. 58 SYNOVIAL MEMBRANES Three classes of synovial membranes have to be described—namely, those lining the cavities of joints, Articular ; those forming closed sacs, Bursal; and those forming lubricating sheaths for tendons, Vaginal or Ensheathing. 1. Articular Synovial Membranes (Synovial Capsules).—These cover the interior of the ligaments enclosing a diarthrodial joint, and secrete a fluid called synovia, which lubricates the articular sur- faces and ensures smooth movement. The membrane is not (as was formerly supposed) continued over the whole surface of the articular cartilage, but simply overlaps its margin to a very slight extent ; at its termination it becomes firmly adherent to the cartilage. When a tendon passes through a joint, as, for instance, the tendon of the biceps through the shoulder joint, it is invested by this membrane, which is often continued on it for some distance beyond the capsule of the joint. In large joints additional folds of synovial membrane. , ning fat, pass between the bones, or are lodged in excavation: i, ’ irti alar surfaces; some of these receive the name of ligaments, others are simply described as synovial fringes. 2. Bursal Synovial Membranes (Bursa; Mucosa').—In these the synovial membrane forms a shut sac, sufficient fluid being secreted to lubricate the opposed surfaces, and the outer surface of the sac being connected with the neighbouring structures. Bursae are found in all places where it is desirable to prevent friction between sur- faces which move on each other; thus they are placed between the tendons of muscles, between tendons and the exterior of certain joints, and sometimes between a muscle and a bone. Many bursae are subcutaneous, and are then of use to ward off external pressure ; such are the bursae found between the skin and the patella, and between the skin and the olecranon, or those on the styloid processes of the radius and ulna. Bursae lying in contact with the capsule of a joint often become connected with the cavity of the joint, 3. Vaginal or Ensheathing Synovial Membranes.—These form sheaths for the tendons of many muscles, more especially those on the palmar and dorsal surfaces of the wrist, and the tendons passing to the phalanges of the fingers and toes. They not only serve to lubricate those tendons, but are also the means by which they are connected with the bones, and with each other; small bands called “frena” passing from one part of the membrane to another. Structure of Synovial Membrane. —Synovial membranes are formed entirely of connective tissue, the deep layer being composed of ramified corpuscles embedded in a ground substance. The free surface was formerly described as being covered by a single layer of flattened epithelial cells, but further investigation has established the fact that the only cells found on the surface are of the branched and anastomosing kind, similar to those in the deeper layer of the tissue, and that the surface between the cells is formed by albuminoid ground substance. Here and There, however, the cells become so aggregated together, as to present some resemblance to an MUCOUS MEMBRANE. 59 epithelial layer ; but this aggregation only takes place in isolated patches, and not over the whole membrane. The synovial membrane passes a little beyond the edge of the articular cartilage, and its cells becoming changed in form and losing their processes come to bear a close resemblance to cartilage cells ; it thus becomes quite impossible to determine the exact spot at which the membrane ceases. Blood-vessels are numerous in the deep layer of synovial mem- branes ; they extend for only a short distance beyond the edge of the cartilage, where they form a circle of anastomosis, the loops of which are distinguished by dilatations. MUCOUS MEMBRANE. Mucous membrane is the tissue which hues- ,u al mrnal pas- sages communicating with the si#t'ace-ot the body. It secretes a viscid fluid called mucus, which protects and lubricates its surface, so as to allow of the passage of substances which otherwise would injure or irritate it. There are two great tracts of mucous mem- brane, called the gastro-pulmonary and genito-urinary. The first communicates with the surface of the body at the edge of the eyelids, nostrils, mouth, and anus ; the second at the orifice of the urethra in the male, of the vagina in the female. Every duct which opens into either of these tracts is a tubular prolongation of the mucous mem- brane ; and the various glands which pour their secretions into the alimentary canal on the one hand, and those connected with the bladder and organs of generation on the other, are but complicated ramifications of that membrane continued to them through their respective ducts. The structure of mucous membrane is analogous to that of serous membrane, but more complex. It consists of two portions— one, the corium, a tough fibro-vascular layer; the other the epi- thelium, composed of one or more layers of cells which rest on the corium. The corium in most situations is separated from the epithelial layer by a thin, transparent membrane—the basement membrane ; it is composed of flattened cells joined by their edges, and is often pierced by numerous openings through which the deeper processes of the epithelial cells pass. Underneath this filmy structure lies the capillary plexus, and on it rest the epithelial cells. The corium consists of a congeries of vessels—capillaries and lymphatics—woven into a compact tissue by interlacing fibres of connective tissiie. The pink colour of mucous membrane depends on the capillary plexus seen through the semi-transparent cellular epithelium. In certain situations plain or involuntary muscular fibres occur as a thin but definite layer on the deep aspect of the corium, forming the muscularis mucosce; this is especially distinct 60 SEChETING GLANDS. in tlie mucous membrane of the alimentary canal, where the fibres may also be traced between the glands, and into the villous pro- jections. Also, in some parts, and especially in the intestinal canal, it contains abundance of lymphoid tissue. The arrangement of the vessels of the capillary plexus differs in each situation, so that a portion of mucous membrane under examination can be recognised by its vessels alone —as, for instance, the villi of the intestines, the air-cells of the lung, &e. The epithelium of mucous membrane may be in a single layer or stratified, and the individual cells may be scaly, columnar, or ciliated. A peculiar variety of epithelium is often seen among the ordinary columnar cells in actively secreting mucous membrane, which has been named “goblet epithelium” or “goblet cells.” The i' xle of its formation from the ordinary columnar cfb'.s has been already described (see p. 9). Submucous Tissue.—The corium is connected to the structures on which it lies by a layer of areolar tissue, which is dense and firm in some situations, where its fibres are continuous with the inter- lacing fibres of the corium ; but in most it is loose, and permits the corium to glide on the surface on which it lies, so that it may be thrown into folds, or rugre. The laxity of this submucous tissue renders it liable to be distended with fluid, as a result of inflamma- tion, as in the case of chemosis of the conjunctiva and oedema of the glottis. The submucous tissue allows of the adaptation of the mucous membrane to the altered size of the organ, according as it is distended or contracted ; it lodges the deeper and larger mucous glands, gives space for the subdivision and distribution of the blood-vessels and nerves, and contains lymph spaces and lymphatic plexuses, in free communication with the lymphatic capillaries of the mucous mem- brane. The arrangement of the mucous membrane, and the structure ol the glands in connection with it, will be described along with the anatomy of the organs of which it constitutes a part. Fio. 71. — Goblet cell from tra- chea of cat. SECRETING GLANDS. The simplest example of secreting structure is to be found in the serous membranes, which have on their surface a layer of endothelial cells, performing the work of secretion; beneath this, a subendotlielial layer formed of connective-tissue corpuscles embedded in an albu- minous ground substance, while in the ground substance and beneath it there is a fine plexus of capillary vessels, furnishing the blood from which the secretion is separated. However complicated glands may appear, it is easy to recognise in them the same three essential constituents as in serous membranes, namely, secreting cells, supporting tissue, and capillary vessels, but SECRETING GLANDS. 61 these three undergo various modifications in the different glands In most of the glands the cells are of a spheroidal or irregular cubica form, and the supporting tissue is reduced to a basement mem- brane. Glands may be divided into six forms, three of them being described as simple, and three as compound. The former are the simple follicle, saccule, and t ubule; the latter the compound follicle, saccule, and tubule. The simple follicle is merely a depression, resembling in shape the finger of a glove, and lined with cells mostly of the columnar variety, but with some granular spheroidal cells intermixed. The narrow cavity between the cells is called the lumen of the gland. The best examples of this form of gland are to be found in the small intestines, where they are called Lieberkulm’s follicles. The simple tubule is an elongated follicle, the deeply seated end becoming convoluted like a ball of twine ; the upper part of the tube is lined with squamous, and the lower with cubical epithelium. The sweat glands of the skin are examples of the simple tubular gland. The simple saccule is a pouch-like sac, dilated below, and con- Fig. 72.—i. Simple follicle. 2. Tubular gland. 3. Saccular gland. Fig. 73.—1. Compound follicle. 2. Compound tubular gland. 3. Compound saccular or racemose gland. nected with the surface above by a narrow neck. The saccule is crowded with cells, chiefly of spheroidal form, so that little or no free cavity or lumen is left. The sebaceous glands connected with the hair follicles of the skin are examples of this form of gland. The compound follicular gland is a follicle, the termination of which is cleft into two or three divisions. The gastric follicles near the pyloric end of the stomach have this form. The compound tubular gland consists of branching tubules which become convoluted at their deep extremity. This arrange- ment may be observed in the tubuli uriniferi of the kidney and seminal tubules of the testicle. The compound saccule is better known under the title of race- 62 SECRETING GLANDS. mose gland. The salivary glands, pancreas, mammary gland, the lachrymal gland, and Brunner’s glands of the duodenum belong to this class. The racemose gland presents to the naked eye the appear- ance of a m»>er of little lobules, held together by connective tissue, and by blood-vessels which enter or leave them. Each lobule is Composed of a number of saccules, called acini, lined by large protoplasmic cells, with nuclei near their attached margins. The cells are so large as almost to till the entire saccule, only a small central cavity or lumen being left between them. The cells are supported by a framework of connective tissue, which serves also to connect the saccules, and to support a network of capillary vessels which supplies blood to the gland cells. The acini of a lobule open into a common duct, and the ducts from the lobules unite to form Fig. 74.—Modes of termination of nerves in salivary glands. 1 and 2. Branching of the nerves between the salivary cells. 3. Termination of the nerve in the nucleus. 4. Union of a ganglion cell with a salivary cell. 5. Varicose nerve fibres entering the cylindrical cells of the excretory ducts. larger ducts, which generally terminate in a single excretory channel for the whole organ ; sometimes, however, as in the lachrymal and sublingual glands, the terminal ducts are eight or ten in number. The ducts are lined with cylindrical epithelium. The blood-vessels distributed to glands are numerous and of large size. They are remarkable for their rapid increase and diminution in size, according to the activity of the gland, or the reverse. The nerves distributed to glands are partly derived from the cerebro- spinal and partly from the sympathetic system ; many of the latter are distributed to the blood-vessels, and serve to regulate (he supply of blood to the gland. The nerves distributed to the salivary glands form a plexus between (lie lobules, in the midst of which small ganglia are found. The plexus is composed chiefly of medullated THE SKIN AND ITS APPENDAGES. 63 fibres, and the branches given off from it are also medullated, till they penetrate the basement membrane of the acini, or the wall of the ducts ; they then lose their medullary sheath, the axis cylinder splits up into numerous primitive fibrils, which pass into the sub- stance of the epithelial cells of the ducts and the gland cells of the alveoli (PfUiger), often reaching the nuclei of those cells. Ganglion cells are also described as directly connected by their processes with the gland cells of salivary glands. THE SKIN AND ITS APPENDAGES. The skin is the exterior investment of the body, which it serves to cover and protect. It is continuous at the aperaires of the in- ternal cavities with the lining membrane of those cavities, the internal skin or mucous membrane, and is composed essentially of two layers, derma and epidermis. The DERMA, cutis vera or corium, is the deep layer of the skin; it is composed of areolar tissue, muscular tissue, and fat, together with numerous blood -' vessels, lymphatics, and nerves, which ramify through it. For convenience of description it is divided into a reticular and pa- pillary layer, but it must be re- membered that these are nowhere separable the one from the other. d'he reticular or deep layer of the derma presents some variety in thickness in different parts of the body. Thus in the more exposed regions, as the back, the outer sides of the limbs, the palms, and the soles, it is remarkable for its thick- ness ; while on protected parts it is comparatively thin, and on the eye- lids, penis, and scrotum is peculiarly delicate. It is connected by its under surface with the common superficial fascia of the body. It is composed chiefly of white fibrous tissue collected into bundles, which are small and closely packed in the upper strata, large and coarse in the deeper strata ; in the latter they form large areohe, which contain adipose tissue, and in the midst of the fibrous bundles the hair- Fig. 75.—Vertical section of skin of finger, a. Epidermis, the surface of which shows hollow depressions, «, a, between the papillary eminences, b, and the openings of the sweat ducts, s; at m is seen the deeper layer of the epidermis, or rete mu- cosum, and opposite a the clear line ■of the stratum lucidum. b. Cutis vera, in which are embedded the sweat glands, d, with their ducts, e, and also aggregations of fat vesicles, f; at g is seen an arterial twig sup- plying the vascular papilla;, p ; and at t one of the touch corpuscles with its nerve. 64 THE SKIN. bulbs and tbe sudoriferous glands are embedded. The superficial strata contain much yellow elastic tissue, the quantity of which varies in different parts of the body, being much increased in the neighbourhood of joints. The deep strata contain unstriped muscular fibres, either gathered into bundles or dispersed among the fibrous tissue. In some parts the muscular tissue is so thick as to form a distinct layer, as in the “ tunica dartos ” of the scrotum, in the nipple and its areola, the penis and the perineum. There are also distinct bands of muscle connected with the hair follicles ; these will be described in speaking of the hairs. Throughout the whole of the reticular layer connective-tissue cor- puscles are found ; they generally anastomose so as to form a net- work. T1 ie papillary or superficial layer of the derma is raised in the form of conical prominences or papillae. On the general surface of the body the papillae are short and exceedingly minute ; but in other situations, as the palmar surface of the hands and fingers, and the plantar surface of the feet and toes, they are long and of large size. They also differ in arrangement; for, on the general surface, they are distributed at unequal distances and without order; whereas, on the palms and soles, and on the corresponding surfaces of the fingers and toes, they are collected into little square clumps, containing from ten to twenty papillae, and these little clumps are disposed in parallel rows. It is this arrangement in rows that gives rise to the characteristic parallel ridges and furrows which are met with on the hands and feet. The papillae in these, little square clumps are for the most part uniform in size and length, but every here and there one papilla may be observed which is longer than the rest. The largest papillae of the derma are those which produce the nail. In structure the papilla is com- posed of homogeneous, nucleated, and fibril bated areolar tissue, with a few transverse elastic fibres. The papillae are separated from the epidermis by an apparently homogeneous basement membrane which becomes evident as a transparent line, when the tissue is treated with a solution of chloride of gold. The papillae are divi- sible into vascular and nervous, the former predominating ; some of the nervous papillae are occupied by a peculiar form of nerve ter- mination called the tactile corpuscle of Meissner or Wagner. The EPIDERMIS or cuticle (scarfskin) covers the superficial surface of the derma, which it serves to envelop and defend. That surface of the epidermis which is exposed to the influence of the atmosphere and exterior sources of injury, is hard and horny in texture, and consists of many layers of horny cell-plates, which are not affected by acetic acid, and in which no nucleus can be made out ; they form the stratum corneum. Beneath these cells is a layer in which the outlines of the cells become indistinct, so that they appear to form a homogeneous stratum, wherein nuclei are seen at intervals ; this is called the stratum lucidum. In the succeeding layers the cells have a granular appearance, and contain a peculiar matter named elcidin ; they are THE SKIN. 65 oval or flattened, and the granular matter contained in them is re- markable for the readiness with which it absorbs colouring matter, such as carmine or hannatoxylin. This layer has received the name of stratum granulosum. The deepest layer of the epidermis is known as the rete mucosum or Malpighian layer; it is divisible into a deep and a superficial stratum. The deep stratum is in contact with the basement membrane covering the papillae, and consists of a layer of Fig. 76.—Section ot' epidermis. H. Horny layer, consisting of s, superficial horny scales; sw, swollen-out horny cells; s.l, stratum lueidum. M. Rete mucosum or Malpighian layer, consisting of p, prickle-cells several rows deep; and c, elongated cells next the derma, n. Nerve-plexus branches of which penetrate between the cells. (Schafer after Ilanvier.) columnar cells ; it is believed that they are the active agents in the selection of nourishment from the corium for the epidermis, and in the production of the new cells of the rete mucosum. By drawing nourishment from the corium they increase rapidly in size, more especially in length ; the upper part then becomes separated from the rest to form a new cell, while the lower part, remaining still attached to the basement membrane, again elongates by the imbition of new material ; again it divides, and so ad infinitum. The cells thus 66 THE SKIN. formed become larger by drawing nourishment from the corium, and it is probable that they also divide to form other cells. As this pro- cess goes on, the newest-formed cells push the older ones away from the corium, and as the latter ascend towards the surface of the skin they undergo certain changes. In consequence of the pressure which they sustain they become flattened ; as they get beyond the range of nutrition they become altered in consistence, and finally they become subject to evaporation. Thus it happens that the cell which is at first spherical becomes elliptical, then becomes still more flattened, and at length desiccates into a thin membranous scale, in which no nucleus is apparent; in this last form it is thrown off. The superficial cells of the rete mucosum are marked on their surface by irregular ridges and furrows, and sometimes by small spines ; the ridges do not lit into the furrows, but the result of their presence is that minute channels are left between the cells which probably serve for the passage of nutrient fluid. Wander-cells are often observed among the cells of the rete mucosum. The under surface of the epidermis is accurately modelled on the papillary layer of the derma, each papilla having its appropriate sheath in the newly- formed rete mucosum, and each ir- regularity of surface of the former having its representative in the soft tissue of the latter. On the external surface, this character is lost; the minute elevations corresponding with the pa- pillae are, as it were, polished down, and the surface is rendered smooth and uniform. The palmar and plantar sur- face of the hands and feet are, however, an exception to this rule ; for here, in consequence of the large size of the papillae and their peculiar arrangement in rows, ridges correspond- ing with the papillae are strongly marked on the superficial surface of the epidermis. The epidermis is remarkable for its thickness in situations where the papillae are large, as in the palms and soles. In other situations, it assumes a character which is also due to the nature of the surface of the derma ; namely, that of being marked by a network of linear furrows which trace out the surface into small polygonal and diamond-shaped areas. These lines correspond with the folds of the derma produced by its movements, and are most numerous where those movements are greatest, as in the flexures and on the convexities of joints. The dark colour of the skin among the natives of the South is due to the presence of pigment granules in the deep cells of the rete Fig. 77.—Diagram illustrative of the development ot the epider- mis and of epithelia in general. 1. A new cell. 2. The cell seen to he increased in size. 3. The spheroidal cell. 4. The oval cell. 5. The elliptical cell. 6. The flattened cell; which, by con- tact of its walls, is speedily con- verted into a scale. 7. A nu- cleated scale as seen on its flat surface. 8. A cluster of such scales. THE SKIN. 67 mucosum. As the cells desiccate, the colour of the granules is lost, so that the cells of the superficial layers are very little darker in the skin of the negro than in that of the white man. The pores of the epidermis are the openings of the sweat ducts, hair follicles, and sebaceous glands. Vessels and Nerves.—The arteries of the derma, which enter its structure through the areolae of the under surface of the corium, divide into innumerable intermediate vessels, which form a rich capillary plexus in the superficial strata of the skin and in its papil- lary layer. In the papillae of some parts of the derma, as in the longitudinal plications beneath the nail, the capillary vessels form simple loops, but in other papillae they are convoluted to a greater or less degree in proportion to the size and importance of the papillae. Capillary plexuses are also found around the groups of fat vesicles, the sweat glands, and hair follicles. The lymphatic vessels form, in the superficial strata of the derma, a plexus, the meshes of which are interwoven with those of the capillary and nervous plexus. In some parts of the palm of the hand and sole of the foot, lymphatics pass into the papillae, but do not reach their summit. The nerves of the derma, after entering the areolae of the deeper part of the corium, divide into minute fasciculi, which form a ter- Fig. 78.—Three groups of tactile papillae from the skin of the index finger, in vertical section. Some are supplied with vascular loops, some with tactile cor- puscles. minal plexus in the upper strata of the corium. From this plexus the primitive fibres pass off to their distribution as loops, in the papillae. In the less sensitive parts of the skin the loops are simple and more or less acute in their bend, in conformity with the figure of the papillae. In the sensitive parts, and especially in the tactile papillae of the pulps of the fingers, the nerves terminate in special sense organs, namely, end bulbs, Pacinian bodies, and tactile cor- puscles ; the two former have already been described (p. 39). Small varicose nerve fibrils pass into the epidermis, and penetrate between the cells of Malpighian layer, to terminate in minute bulbous ends, without anastomosing. The tactile corpuscles (discovered by Wagner and Meissner) are oval bodies about rs)y(T inch long, having externally a capsule of connective tissue with oval nuclei, some of the fibres being wound round horizontally and in many places penetrating into the central 68 APPENDAGES OF THE SKIN. part or core. The latter appears to be formed of modified con- nective tissue; the nerve fibres lose their medullary sheath before entering it, they then run a convoluted course (many of them be- coming varicose), and terminate in bulbous enlargements. APPENDAGES OF THE SKIN The appendages of the skin are the nails, hairs, sebaceous glands, and sweat glands and ducts. The NAILS are horny appendages of the skin, identical in forma- tion with the epidermis, of which they are a part. A nail is convex on its external surface, concave within, and implanted by means of a thin margin or root in a fold of the derma, which is nearly two lines in depth, and acts the part of a follicle to the nail. At the bottom of the groove of the follicle are a number of filiform papillae, which produce the margin of the root, and, by a successive forma- tion of new cells, push the nail onwards in its growth. The concave surface of the nail is in contact with the derma, and the latter forms the matrix of the nail, and is covered by papillae, which perform the double office of retaining the nail in its place, and giving it in- creased thickness by the addition of newly-formed cells to its under surface. It is this constant change occurring in the under surface of the nail, co-operating with the continual formation taking place along the margin of the root, which ensures the growth of the nail in the proper direction. The nail derives a peculiarity of appear- ance from the disposition and form of the papillae of the matrix. Thus, beneath the root, and for a short distance onwards towards its middle, the derma is covered by papillae which are more minute, and consequently less vascular than the papillae somewhat farther on. This patch of papillae is hounded by a sfemilunar line, and that part of the nail covering it being lighter in colour than the rest, has been termed lunula. Beyond the lunula the papillae are raised into longitudinal pleats, which are exceedingly vascular, and give a deeper tint of redness to the nail. These pleat-like papillae of the derma are well calculated by their form to offer an extensive surface both for the adhesion and formation of the nail. It is the deposit of horny laminae on the surface of these folds that gives rise to the ribbed appearance of the nail. The papillary substance of the derma which produces the nail is continuous around the circumference of the attached part of that organ with the derma of the surrounding skin, and the horny structure of the nail is consequently continuous with that of the epidermis. HAIRS are horny appendages of the skin, produced by the invo- lution and subsequent evolution of the epidermis ; the involution constituting the follicle in which the hair is enclosed, and the evolu- tion the shaft of the hail-. Hairs vary much in size and length in dif- ferent parts of the body ; in some they are so short as not to appear beyond the follicle ; in others they grow to a great length, as on the APPENDAGES OF THE SKIN. 69 scalp ; while along the margins of the eyelids, and in the whiskers and heard, they are remarkable for their thickness. Hairs are generally more or less flattened in form, and on transverse section present an elliptical or reniform outline. This examination also demon- strates that the centre of the hair is porous and loose in texture, while its periphery is dense; thus affording ground for its division into a cortical and a medullary portion. The free extremity of a hair is gene- rally pointed, and sometimes split into two or three fila- ments. Its attached extremity is implanted deeply in the in- tegument, extending through the derma into the subcutaneous areolar tissue, where it is sur- rounded by adipose tissue. The central extremity of a hair is larger than its shaft, and is called the root or bulb. It is rounded or conical in shape. The outer surface of the hair is Covered by a layer of flattened cells, which overlap each other at the edges like the tiles of a house. The bulk of the shaft consists of cells which have become flattened, elongated, and welded together, the union being often so intimate that no indication of the individual elements from which it is formed can be made out, except by the aid of chemical re- agents. Very small elongated nuclei may be demonstrated among the fibres, and occasional dark streaks, some of which are due to deposits of pigment, and others to air spaces. The bulb of the hair has projecting into it a small process or papilla from the derma; it contains blood- vessels and nerves, and furnishes nutriment to the cells of the bulb, by the multiplication of which the hair increases in size. The hair is contained in a de- pression passing deeply into the reticular layer of the corium, and Fig. 79.—The hairs and their connections, x. Hair bulb. 2. Inner sheath of the fol- licle. 3. Sebaceous gland. 4. Erector pili muscle. Fig. 8o.—Section of a hair follicle, i. Epidermic coat of follicle or root-sheath. 2. Dermic coat. a. Outer layer of dermic coat with blood-vessels, b, b, cut across; c, middle layer; d, inner or hyaline layer; e, outer root-sheath; /, g, inner root-sheath ; 7t, cuticle of root- sheath ; i, hair. (Schafer after Biesiadecki.) APPENDAGES OF THE SKIN. 70 called the hair follicle. It is wide in its deepest part where it contains the bulb, gets narrower at the entrance of the ducts of the sebaceous glands, and again widens as it nears the surface. Its wall consists of two distinct layers, called respectively the external and internal sheath of the follicle, the former being continuous with the corium, and the latter with the epidermis. The external or dermic sheath is formed in its outer layers of longitudinal bundles of connective tissue, in which corpuscles are found, but no elastic fibres ; internally it is distinguishable as a transparent homogeneous membrane, which corresponds to the basement membrane support- ing epithelium in other tissues. The internal or epidermic sheath adheres closely to the root of the hair, and generally comes away with the latter when it is pulled out; hence it is called the root- sheath. It is also described as composed of an outer and an inner layer. The outer root-sheath corresponds to the rete mueosum of the epidermis, and is composed of soft polygonal nucleated cells, which in the coloured races are generally pigmented ; these cells become continuous at the bottom of the follicle with those forming the hair bulb. The inner root-sheath is again divisible into an inner layer (Huxlej/s sheath), formed of flattened, polygonal nucleated cells, two or three deep ; and an outer layer (JJenle’s sheath) of oblong, flattened cells, without nuclei. On the inner surface of the inner root-sheath is a thin stratum of imbricated scales, closely applied to the surface of the hair, and forming the cuticle of the root-sheath. Connected with the hair follicles there are some fine bands of un- striped muscular fibre. These arise from the superficial part of the corium, and are inserted into the out- side of the lower part of the follicle, below the sebaceous gland. They are placed on the side towards which the hair slopes, and by their contraction erect the hair; hence they have re- ceived the name of erectores pili. The colour of the hair is due to pigment deposited in the central cells. The SEBACEOUS GLANDS are em- bedded in the substance of the derma, and present every degree of com- plexity, from the simplest follicle to the compound lobulated gland. In some situations their excretory ducts open independently on the surface of the epidermis ; but for the most part they terminate in the follicles of the hairs. The sebaceous glands associated with the hairs are racemose and lobulated, consisting of glandular vesicles lined with polyhedral or spheroidal cells; the central cavity of the gland is occupied by round cells containing fat, mixed Fig. 81.—A sebaceous gland, a. Tlie gland vesicles, b. Excretory duct. c. The follicle of a downy hair. d. Shaft of the latter. with epithelial and fatty debris, forming the glandular secretion. The ducts of the several acini unite to form a common duct, and the latter, after a short course, terminates in the hair follicle. In the seal}) there are two of the glands to each hair follicle. On the nose and face the glands are of large size, and constantly associated with small hair follicles. The ducts are lined by an inversion of the epidermis, which forms a thick and funnel-shaped cone at its commencement, but soon becomes uniform and soft. Sebaceous glands are met with in all parts of the body, but are most abundant in the skin of the face, and in those situations which are naturally exposed to the influence of friction. The SUDORIFEROUS or SWEAT GLANDS are situated deeply in the corium and also in the subcutaneous areolar tissue, where they are surrounded by adipose tissue. They are small round or oblong bodies, com- posed of one or more convoluted tubuli, which open into a common efferent duct. The latter ascends from the gland through the derma and epider- mis, and terminates on the surface by a funnel-shaped and oblique aperture or pore. Each gland mass is surrounded by a fine plexus of capillary vessels. The efferent duct presents some variety in its course upwards; within the derma it is straight, or curved and serpentine, and if the epidermis be thin, proceeds more or less directly to the excreting pore. Some- times it is spirally curved within the" derma, and having passed the latter, is regularly and beautifully spiral in its passage through the epidermis, the last forming an oblique and valvular opening on the surface. The spiral course of the duct is especially remarkable in the thick epidermis of the palm of the hand and sole of the foot. On those parts of the skin where the papillae are irregularly dis- tributed, the efferent ducts of the sudoriferous glands open on the surface also irregularly, while on the palmar and plantar surfaces of the hands and feet, the pores are situated at regular distances along the ridges, at points corresponding with the intervals of the small, appendages of the skin. Fig. 82.—Sudoriferous gland and its capillary plexus. a. Convoluted portion, b. Excretory duct, c, c. Basket- like capillary plexus from around a convolution, with arterial twigs. APPENDAGES OF THE SKIN. 72 square-shaped clumps of papillae. Indeed, the apertures of the pores, seen on the surface of the epidermal ridges, give rise to the appear- ance of small transverse furrows, which intersect the ridges from point to point. The efferent duct of the sudoriferous gland is lined by epithelium consisting of one or more strata of cells ; the convoluted tubule forming the deep part of the gland is lined by a single layer of cubical cells, supported by a basement membrane. The latter are the secreting cells of the gland ; they often have a vertical striation, giving them the appearance of being made up of a series of rods, a character they possess in common with the cells of the kidney and other secreting organs. In some of the larger glands a longitudinal layer of unstriped muscular fibre is found in the outer coat, in addition to the connective tissue which forms this coat in the rest of the glands. The ceruminous glands of the external auditory meatus are regarded as modified sweat glands, but their secretion in some respects re- sembles that of the sebaceous glands. PART II. OSTEOLOGY. The skeleton is the bony framework which forms the support of the body, and affords points of attachment for the muscles by which the movements are effected. The fundamental part of the skeleton is the spine or vertebral column (from verto, I turn), because it is the axis around which all the other parts are disposed and on which they move. It exists in all animals possessing an internal skeleton, which are therefore called vertebrate animals. The entire osseous framework of the body constitutes the skeleton, which in the adult man is composed of two hundred distinct bones. They may be thus arranged :— Cranium. .... 8 Face . . . . .14 • Skull Axial skeleton ' Vertebral column . . .24 Sacrum and coccyx . . 2 Os hyoides 1 ,Sternum and ribs . . -25 Appendicular skeleton Upper extremities . . .64 Lower extremities . . .60 Patellae ..... 2 200 In addition to this number, there are six ossicles of the ear and a variable number of sesamoid bones. GENERAL CHARACTERS OF BONES. Bones are divisible into four classes :—Long, flat, short, and irregular. The long bones are found principally in the limbs, and consist of a shaft and two extremities. The shaft is cylindrical or prismoid in form, dense and hard in texture, and hollowed in the interior into a medullary canal. The extremities are broad and expanded to articulate with adjoining bones ; and are cancellous in internal 74 structure. Upon the exterior of the hones are processes and rough surfaces for the attachment of muscles, and foramina for the trans- mission of vessels and nerves. The character of long bones is, there- fore, their general type of structure and their divisibility into a central portion and extremities, and not so much their length ; for there are certain long bones, as the second phalanges of the toes, which are less than a quarter of an inch in length, and which, in some instances, exceed in breadth their longitudinal axis. The long bones are, the clavicle, humerus, radius and ulna, femur, tibia and fibula, metacarpal bones, metatarsal, phalanges, and ribs. Flat bones are composed of two layers of dense bone with inter- mediate loose structure. They are adapted to enclose cavities ; have processes upon their surface for the attachment of muscles ; and are perforated by foramina for the passage of nutrient vessels to the cavities in their interior, and for the transmission of vessels and nerves. They articulate with long bones by means of smooth sur- faces plated with cartilage, and with each other, either by fibro- cartilaginous tissue, as at the symphysis pubis ; or by suture, as in the bones of the skull. The two condensed layers of the bones of the skull are named, tables; and the intermediate open structure, diploe. The flat bones are, the occipital, parietal, frontal, nasal, lachrymal, vomer, sternum, scapulae, and innominate bones. Short bones have an exterior shell of dense bone filled with spongy or cancellous substance ; of this sort are the bones of the carpus and tarsus, and the seasamoid bones, including the patella. The irregular bones include all that remain after the long, short, and flat bones have been excluded. They are essentially irregular in their form, in some parts Rat, in others short and thick ; and are constructed on the same general principle as other bones. The bones of this class are, the temporal, sphenoid, ethmoid, superior maxillary, inferior maxillary, palate, inferior turbinated, hyoid, ver- tebrae, sacrum, and coccyx. The skeleton is divisible into : I. The vertebral column, or central axis. 2. The head and face, or superior development of the central axis. 3. The hyoid arch. 4. The shoulder girdle and upper ex- tremities. 5. The pelvic girdle and lower extremities. VERTEBRAL COLUMN. VERTEBRAL COLUMN. The vertebral column is the central axis which supports the head, thorax, and upper extremities. It consists of numerous sepa- rate bones called vertebra, which, although possessing a limited degree of motion on each other, yet give to the whole column considerable flexibility. The vertebrae admit of a division into true and false. The true vertebrae are twenty-four in number, and are classed, according to the three regions of the trunk which they occupy, into cervical, dorsal, and lumbar. The false or fixed vertebrae consist of nine CERVICAL vertebra:. pieces united into two bones, the sacrum and coccyx. The arrange- ment of the vertebra? may be better comprehended by means of the accompanying table :— True vertebra? 24 7 Cervical, 12 Dorsal, 5 Lumbar. False vertebra? 9 5 Sacrum, 4 Coccyx. Characters of a Vertebra.—A vertebra consists of a body or centrum, two lamina1, a spinous process, two transverse processes, and four articular processes. The body or centrum is the solid part of the vertebra ; and, by its articulation with adjoining vertebrae, gives strength and support to the trunk. It is flattened above and below, convex in front, and slightly concave behind. Its anterior surface is constricted around the middle, and pierced by numerous small openings, which give passage to nutrient vessels. On its posterior surface is a single irregular opening, or several, for the exit of the venae basis vertebrae. The laminae commence upon the sides of the posterior part of the body of the vertebrae by two pedicles; they then expand, and, arching backwards, enclose a foramen (neural canal), which serves for the protection of the spinal cord. The upper and lower borders of the laminae are rough for the attachment of the ligamenta subflava. The concavities above and below the pedicles are the intervertebral notches. The spinous process stands backwards from the angle of union of the laminae. It is the succession of these projecting processes along the middle line of the back, that has given rise to the common designa- tion of the vertebral column, the spine. The use of the spinous pro- cess is for the attachment of muscles. The transverse processes project one at each side from the laminae of the vertebra; they also are intended for the attachment of muscles. The articular processes, four in number, stand upwards and downwards from the laminae, to articulate with the vertebra above and below. Cervical Vertebrae.—In a cervical vertebra the body is smaller than in the other regions; it is broad from side to side, con- cave on the upper surface and convex below, so that, when articu- lated, the vertebrae lock the one into the other. The lateral borders of the upper surface are produced into prominent ridges, and the anterior edge of the lower surface overlaps that of the vertebra below. The laminae are narrow and long, and the included spinal foramen large and triangular. The superior intervertebral notches are slightly deeper than the inferior ; the inferior being the broadest. The spinous process is short and bifid at the extremity, increasing in length from the fourth to the seventh. The transverse processes are also short and bifid, and deeply grooved along the upper surface for the cervical nerves. Piercing the base of the transverse process is the vertebral foramen, which gives passage to the vertebral artery and vein, and vertebral plexus of nerves. The artery commonly passes only through the vertebral foramina of 76 the six upper vertebrae ; the vein more frequently passes through the foramina of all seven. The transverse processes in this region are formed by two small developments, which proceed, the one from the side of the body, the other from the pedicle, and unite near their extremities to enclose the circular area of tlie vertebral foramen. The anterior of these processes is the rudiment of a cervical rib ; the posterior, the homologue of the transverse processes in the dorsal region. The extremities of these developments are the anterior and CERVICAL VERTEBRAS. Fkj. 83.—A middle cervical vertebra, seen upon its upper surface. 1. The body, con- cave in the middle, and rising on each side into a sharp ridge. 2. The lamina. 3. The pedicle, rendered concave by the superior intervertebral notch. 4. The bifid spinous process. 5. The bifid transverse process. The number is placed in the concavity between the anterior and pos- terior tubercle. 6. The vertebral foramen. 7. The superior articular process, looking backwards and upwards. 8. The inferior articular process. posterior tubercle of tlie transverse process.* The articular processes are oblique ; the superior looking upwards, backwards, and a little inwards ; the inferior downwards, forwards, and a little outwards. There are three peculiar vertebrae in the cervical region :—The first, or atlas; the second, or axis ; and the seventh, or vertebra prominens. The Atlas (named from supporting the head) is a simple ring of Fig. 84. —The upper surface of the atlas. 1. The anterior tubercle proj ecting from the anterior arch. 2. The articular surface for the odontoid process on the posterior surface of the anterior arch. 3. The posterior arch, with its rudi- mentary spinous process. 4. The intervertebral notch. 5. The transverse process. 6. The verte- bral foramen. 7. Superior articu- lar surface. 8. Tubercle for the attachment of the transverse liga- ment. hone, without body, and composed of arches and processes. The anterior arch is the shortest; it has a tubercle on its anterior surface, for the attachment of the longus colli muscle ; and on its posterior aspect a smooth surface, for articulation with the odontoid process of the axis. The posterior arch is longer and more slender than the anterior, and flattened from above downwards ; at its middle is a rudimentary * The anterior tubercle of the sixth cervical vertebra is more prominent than the rest; it has been named the carotid tubercle, from its close relation to the common carotid artery, and Chassaignae’s tubercle, from the author who first pointed out this relation. CERVICAL VERTEBRAL spinous process, which gives origin to the rectus capitis posticus minor muscle ; and upon its upper surface, near the articular pro- cesses, a shallow groove at each side (sometimes converted into a foramen), which represents a superior intervertebral notch, and supports the vertebral artery (just before it perforates the dura mater) and the first cervical nerve. The intervertebral notches are peculiar, from being situated behind the articular processes, instead of before them as in the other vertebrae. The transverse processes are not bifid ; they are remarkably large and long, and give attach- ment to the oblique muscles which rotate the head ; they are pierced by the foramina for the vertebral arteries. The articular processes are situated on the most bulky and strongest part of the atlas. The superior are oval and concave, and look inwards, so as to form a kind of cup for the condyles of the occipital bone, and are adapted to the nodding movements of the head ; the inferior are circular, and nearly horizontal, to permit of the rotatory movements. Upon the inner face of the lateral muss which supports the articular pro- cesses, is a small tubercle at each side, to which the extremities of the transverse ligament are attached, a ligament which divides the ring of the atlas into two unequal segments : the smaller and ante- rior, for receiving the odontoid process of the axis ; the larger and posterior, to give passage to the spinal cord and its membranes. The Axis (vertebra dentata) is so named from having a process shaped like a tooth, forming a pivot upon which the head turns. The Pig. 85.—A lateral view of the axis. 1. The body ; the number is placed on the depression which gives attachment to the longus colli. 2. The odontoid process. 3. The smooth facet on the anterior surface of the odontoid process which articulates with the anterior arch of the atlas; ttie facet for the transverse ligament is beneath No. 2, where the constriction called the neck of ttie odontoid process is seen. 4. The lamina. 5. The spinous process. 6. The transverse process, pierced obliquely by the vertebral foramen. 7. The superior articular surface. 8. The inferior articular process. body is of large size, and supports a strong process, the odontoid, which rises perpendicularly from its upper surface. The odontoid process presents two articulating surfaces ; one on its anterior face, to articulate with the anterior arch of the atlas ; the other on its pos- terior face, for the transverse ligament: the latter surface constricts the base of the process, which has given rise to the term neck applied to this part. The tip of the odontoid process is often marked by a spine or ridge which gives attachment to the middle check ligament (ligamentum suspensorium dentis). Upon each side of its apex is a rough depression, for the attachment of the lateral odontoid or check ligaments ; and running down from its base, on the anterior surface of the body of the vertebra, a vertical ridge, with a de- pression at each side for the attachment of the longus colli muscle. The lamince are large and strong, and unite posteriorly to form a bifid 78 spinous process, which is concave beneath, and by its upper surface gives attachment to the inferior oblique muscle. The transverse processes are rudimentary, not bifid, and project only so far as to enclose the vertebral foramen, which is directed obliquely outwards instead of perpendicularly as in the other vertebrae. The superior articulating processes are situated on the body of the vertebra, at each side of the odontoid process. They are circular and nearly horizontal, having a slight inclination outwards. The inferior articu- lating processes look downwards and forwards, as do the same pro- cesses in the other cervical vertebrae. The superior intervertebral notch is remarkably shallow, and lies behind the articular process as in the atlas ; the inferior notch lies in front of the articular process, as in the rest of the vertebrae. The lower surface of the body is convex, and is received into the concavity upon the upper surface of the third vertebra. The Vertebra prominens, or seventh cervical, approaches in char- acter the upper dorsal vertebrae. It has received its designation from having a very long spinous process, which is single and termi- nated by a tubercle, and forms a projection on the back part of the neck ; to the extremity of this process the ligamentum nuchae is attached. The transverse processes are but slightly grooved along the upper surface, have each a small foramen for the transmission of the vertebral vein, and present only a rudimentary bifurcation at their extremity. Sometimes the anterior tubercle represents a small but distinct rib. Dorsal Vertebrae.—The body of a dorsal vertebra is as long from before backwards as from side to side, particularly in the middle of DORSAL VERTEBRAL Fig. 86.—Lateral view of a dorsal vertebra, i. The body. 2, 2. Articular facets for the heads of ribs. 3. The pedicle. 4. The supe- rior intervertebral notch.. 5. The inferior intervertebral notch. 6. The spinous pro- cess. 7. The extremity of the transverse process, marked by an articular surface for the tubercle of a rib. 8. T he two superior articular processes looking backwards. 9. The two inferior articular processes looking forwards. the dorsal region ; it is thicker behind than before, and marked on each side by two half-articulating surfaces for the heads of two ribs. Its upper and lower surfaces are somewhat heart-shaped, and are nearly Hat, but have a slightly sunken centre, with distinct margins of dense, smooth bone ; in the recent state this is occupied by a plate of cartilage. The pedicles are strong, and the lamina: broad and thick ; the spinal foramen small and round, and the inferior intervertebral notch of large size ; the superior can scarcely lie said to exist. The spinous process is long, prismoid, directed very obliquely downwards, and terminated by a tubercle. The transverse processes are large and strong, and directed obliquely backwards. Upon the anterior and superior aspect of their summits is a small facet for the articulation of the tubercle of a rib. The articular processes are nearly vertical, the superior facing backwards, slightly upwards and outwards ; the inferior forwards, slightly downwards and inwards. The peculiar vertebrae in the dorsal region are, the first, ninth, DORSAL VERTEBRA1]. 79 Fig. 87.—The ninth, tenth, eleventh, and twelfth dorsal vertebrae, showing their characteristic peculiarities. tenth, eleventh, and twelfth. The first dorsal vertebra approaches very closely in character the last cervical. The body is broad from side to side, and concave above. It has an entire articular surface for the first rib, and a half surface for the second. The superior articular processes are oblique, and the spinous process horizontal. The ninth dorsal vertebra has onlv one half-articular surface at 80 each side of the upper part of the body. The tenth has a single entire articular surface at each side. The eleventh and twelfth have each a single entire articular surface at each side; they approach in character the lumbar vertebrae; their transverse processes are very short, and have no articulation with the cor- responding ribs. The articular facets are placed partly on the thick and strong laminae, and partly on the bodies. The transverse processes of the twelfth dorsal vertebra are rudimentary, and are marked by three elevations, the external, inferior and superior tubercles, corresponding to the transverse, accessory and mammillary tubercles of lumbar vertebrae ; traces of like tubercles are also observed in the tenth and eleventh vertebrae. The inferior articular processes of the last dorsal are convex and look outwards. Lumbar Vertebrae.—These are the largest pieces of the vertebral column. The body is broad and large, its upper and lower surfaces are nearly Hat, and present a kidney-shaped outline. The pedicles very strong; the laminae short, thick, and broad; the inferior intervertebral notches very large, and the spinal foramen large and oval. The spinous process is thick and broad. The transverse processes LUMBAR VERTEBRAE. Fig. 88.—Lateral view of a lumbar ver- tebra. i. The body. 2. The pedicle. 3. The superior intervertebral notch. 4. The inferior intervertebral notch. 5. The spinous process. 6. The trans- verse process. 7. The superior arti- cular processes. 8. The inferior arti- cular processes. 9. The mammillary process. are slender, pointed, and directed very slightly backwards. The superior articular processes are concave, and look backwards and inwards; the inferior convex, looks forwards and outwards. The superior are much wider apart than the inferior, and embrace the inferior pair of the vertebra above. Projecting backwards and up- wards from the superior articular process is a convex oval tubercle called the mammillary process (metapophysis), and in a well-marked vertebra there is at the base of this a smaller tubercle called the accessory process (anapophysis). The fifth lumbar vertebra differs from the rest in having the body very much bevelled posteriorly, so as to lie thick in front and thin behind ; the transverse processes are thick and large, the lower articular processes are wider apart than the upper, and the laminae project into the spinal foramen on each side. General Considerations.—Viewed as a whole, the vertebral column represents two pyramids applied base to base, the superior being formed by all the vertebrae from the second cervical to the last lumbar, the inferior by the sacrum and coccyx. Examined more attentively, it will be seen to be composed of four irregular pyramids, applied to each other by their smaller extremities and by their bases. VERTEBRAL COLUMN. 81 The smaller extremity of the uppermost pyramid is formed by the axis, or second cervical vertebra ; and its base, by the first dorsal. The second pyramid is inverted ; having its base at the first dorsal, and the smaller end at the fourth. The third pyramid commences at the fourth dorsal, and gradually enlarges to the fifth lumbar. The fourth pyramid is formed by the sacrum and coccyx. The bodies of the vertebrae are broad in the cervical region ; narrowed almost to an angle in the middle of the dorsal, and again broad in the lumbar region. The arches are broad and imbricated in the cervical and dorsal regions, the inferior border of each overlapping the superior of the next; in the lumbar region an interval is left between them. A considerable interval exists between the cranium and atlas, and another between the last lumbar vertebra and sacrum. The spinous processes are horizontal in the cervical, and become gradually oblique in the upper part of the dorsal region. In the middle of the dorsal region they are nearly vertical, and imbricated ; towards its lower part they assume the direction of the lumbar spines, which are quite horizontal. The transverse processes, although very prominent in the atlas, become almost rudimentary in the axis ; they then gradually in- crease in length to the first dorsal vertebra. In the dorsal region they project obliquely backwards, and diminish suddenly in length in the eleventh and twelfth vertebrae, where they are very small. In the lumbar region they suddenly increase in size, the last lumbar being especially large and strong. The intervertebral foramina formed by the juxtaposition of the intervertebral notches are smallest in the cervical region, and gra- dually increase to the last lumbar. On each side of the spinous processes, and extending the whole length of the column, is the vertebral groove, which is shallow and broad in the cervical, and deeper and narrower in the dorsal and lumbar regions. It lodges the principal muscles of the back. Curves of the Vertebral Column.—Viewed from the side, the vertebral column presents several curves, the principal of which is situated in the dorsal region, the concavity looking forwards. In the cervical and lumbar regions the column is convex in front; and in the pelvis an anterior concave curve is formed by the sacrum and coccyx. The dorsal curve is due to the bodies of the vertebrae in that region being thicker behind than in front; the cervical curve depends on the greater thickness of the intervertebral substance in front, and the lumbar curve results in the lower part from the thick- ness of the body of the last vertebra anteriorly, and in the upper part from the intervertebral substance being thicker in front. Besides the antero-posterior curves, a slight lateral curve sometimes exists in the dorsal region, having its convexity towards the right side. It is probably caused by habitual faulty posture in working at trades, associated with the use of the right hand. Development.—The vertebrae are developed by three primary and VERTEBRAL COLUMN. Fig 89.—Posterior and lateral view of spinal column. five secondary centres or epiphyses. The primary centres are, one for each lamina, and one for the body ; the epiphyses, one for the apex of the spinous process, one for that of each transverse process, one for the upper and one for the under surface of the body. Excep- tions to this mode of development are met with in the atlas, axis, vertebra prominens, and lumbar vertebra). The atlas has three centres ; one for each lateral mass, and one (sometimes two) for the anterior arch. The axis has six ; one (sometimes two) for the body ; two placed side by side in the base of the odontoid process, and a third at its tip ; lastly, one for each lamina. The vertebra prominens lias two additional centres for the anterior or costal segments of the transverse processes, and the lumbar vertebrce, two for the mammillary processes. The primary centres of the vertebrae make their appearance during the seventh or eighth week of embryonic existence, the laminae being somewhat in advance of the body. From the laminae are produced the spinous, transverse, and articular processes, and the sides of the body ; they unite, to complete the arch, one year after birth, and with the body during the fifth year. The epiphyses for the extremi- ties of the spinous and transverse processes make their appearance at fifteen or sixteen, and become united to the rest of the bone between twenty and twenty-five. The epiphyses of the body are somewhat later in appearance, and are consolidated between the periods of twenty-five and thirty years of age. The ossific centres for the lateral masses of the atlas appear at the same time as those of the other vertebrae ; they unite posteriorly at the end of the second year. The one or two centres of the anterior arch appear during the first year, and become consolidated with the lateral pieces during the fifth or sixth year. The axis develops its lateral pieces at the same time as the other vertebrae ; they join posteriorly soon after birth, and with the body during the fourth or fifth year. The centres for the body and odontoid process appear during the sixth month, and are consolidated during the third year. The body of the axis is more largely developed at birth than that of the other vertebrae. The costal segments of the vertebra prominens appear during the sixth month, and become united to the body at the fifth or sixth year ; they sometimes remain permanently separate, and constitute cervical ribs. The lumbar vertebrae have separate centres for the mammillary processes, but the transverse process of the first lumbar is sometimes developed altogether from a separate centre, and may remain permanently separate, in that case forming a lumbar rib. The ossification of the arches of the vertebrae commences from above, and proceeds gradually downwards ; hence arrest of develop- ment gives rise to spina bifida, generally in the loins. Ossification of the bodies, on the contrary, commences near the centre, and pro- ceeds towards the extremities of the column ; hence imperfection of the bodies occurs either in the upper or lower vertebrae. Attachment of Muscles.—To the atlas are attached nine pairs VERTEBRAL COLUMN. 83 84 SACRUM. of muscles, the longus colli, rectus anticus minor, rectus lateralis, rectus posticus minor, oblicpius superior and inferior, splenius colli, levator anguli scapulae, and first intertransverse. To the axis are attached eleven pairs—viz., longus colli, inter- transverse, obliquus inferior, rectus posticus major, interspinal, semi- spinalis colli, multifidus spinae, levator anguli scapulae, splenius colli, transversalis cervicis, and scalenus medius. To the remaining vertebra: collectively, thirty-one pairs and one single muscle—viz., posteriorly, trapezius, latissimus dorsi, levator anguli scapulae, rhomboideus minor and major, serratus posticus superior and inferior, splenius, sacro-lumbalis, longissimus dorsi, spinalis dorsi, cervicalis ascendens, transversalis cervicis, trachelo- mastoid, complexus, semispinalis dorsi and colli, multifidus spinae, interspinal, intertransverse, levatores costarum : anteriorly, rectus anticus major, longus colli, scalenus anticus, medius, and posticus, psoas magnus, psoas parvus, quadratus lumborum, diaphragm, obliquus interims and transversalis. The SACRUM is a triangular bone, situated at the lower extremity of the vertebral column, and formed by the consolidation of five Kj. go.—The sacrum seen upon its anterior surface, i, i. Transverse lines marking the original constitution of the bone of five pieces. 2, 2. Anterior sacral foramina. 3. Promontory of the sacrum. 4. Auricular surface to articulate with the ilium. 5. The sharp edge to which the sacro-iscliiatic liga- ments are attached. 6. The vertebral articu- lar surface. 7. The broad triangular surface which supports the psoas muscle and lumbo- sacral nerve. 8. Articular process of the right side. 9. Inferior extremity, or apex of the sacrum. 10. One of the sacral cornua. 11. The notch which is converted into a foramen by the coccyx. false vertebrae. It is divisible into an anterior and posterior surface, two lateral and a superior border, and an inferior extremity. The anterior surface is concave, and marked by four transverse lines, which indicate its original constitution of five separate pieces. At the extremities of these lines, on each side, are. the four anterior sacral foramina, which diminish in size from above downwards, and transmit the anterior sacral nerves. The ridges between the anterior sacral foramina give attachment to the pyriformis muscle. The projection of the superior piece is the sacro-vertebral angle or pro- montory. The posterior surface is narrower than the anterior, and convex. O11 a middle line is a rough crest, formed by the rudiments of four spinous processes, the fifth remaining undeveloped, and exposing the lower termination of the sacral canal. Immediately external to and SACRUM. parallel with the median crest, is a range of five small tubercles which represent the articular processes of the true vertebra;; beyond these is a shallow groove in which the four posterior sacral foramina open, and farther outwards, a range of five tubercles corresponding with the transverse processes of the lumbar vertebrae. The lowest pair of articular tubercles bound on each side the termination of the sacral canal, and send each a process downwards to articulate with the coccyx. The two descending processes are the sacral cornua. The posterior sacral foramina are smaller than the anterior, and transmit the posterior sacral nerves. Of the posterior transverse tubercles the first corresponds with the angle of the superior border of the bone; the second is small, and enters into the formation of the sacro-iliac articulation ; the third is large, and gives attachment to the oblique sacro-iliac ligament; the fourth and fifth are smaller, and serve for the attachment of the sacro-ischiatic ligaments. The lateral border of the sacrum presents superiorly a broad and 85 Fig. 91.—Posterior view of the sacrum. 1, 1. The four rudimentary spinous processes. 2. The sacral canal. 3, 3. Rudimentary arti- cular processes. The lowest of these pro- cesses, with the corresponding process of the opposite side, 4, are the sacral cornua. 5, 5, The four posterior sacral foramina. 6, 6. Posterior transverse tubercles. 7. The auricular surface. 8. Siiarp edge for the attachment of the sacro-ischiatic ligaments. 9. Surface for articulation with the body of the last lumbar vertebra. 10, 10. Articu- lating facets of the articular processes. 11. Apex of the sacrum by which it articulates with the coccyx. 12. Rough surface for the attachment of the posterior sacro-iliac ligaments. ear-shapecl (auricular) surface to articulate with the ilium ; and interiorly a sharp edge, to which the greater and lesser sacro-isehiatic ligaments are attached. The hack part of this border is marked by rough prominences and deep depressions for the posterior sacro-iliac ligaments. On the superior border, in the middle line, is an oval articular surface, corresponding with the under part of the body of the last lumbar vertebra ; and on each side a broad triangular surface, which supports the lumbo-sacral nerve and psoas magnus muscle. Immedi- ately behind the vertebral articular surface is the triangular entrance of the sacral canal; and, on each side of this opening, an articular process, which looks backwards and inwards, like the superior arti- cular processes of the lumbar vertebrae. In front of each articular process is an intervertebral notch. The inferior extremity of the bone presents a small oval surface which articulates with the coccyx ; and on each side a notch, which, 86 SACRUM AND COCCYX. with a corresponding notch in the upper border of the coccyx, forms the foramen for the transmission of the fifth sacral nerve. The sacrum presents some variety in respect of curvature, and of the number of pieces which enter into its structure. The curve is often very slight, and situated only near the lower part of the bone : while in other subjects it is considerable, and occurs at the middle of the sacrum. It is sometimes composed of six pieces, more rarely of four, and, occasionally, the first and second pieces remain perma- nently separate. The female sacrum is wider and shorter than the male, its curvature is less, and is almost confined to the lower part of the bone ; it also forms a greater angle with the rest of the verte- bral column. Development.—By thirty-five points of ossification ; five for each of the first three pieces—viz., one for the body, one for each lateral portion, and one for each lamina ; and three for each of the last two—namely, one for the body and one for each lateral portion. In the progress of growth, and after puberty, fourteen epiphyseal centres are added—namely, two for the surfaces of each body, one for each auricular surface, and one for the thin edge of each lateral border. Ossification begins in the bodies of the sacral pieces somewhat later than in those of the true vertebrae ; the first three appearing during the eighth and ninth week, and the last two at about the middle of intra-uterine existence. Ossification of the laminae takes place during the interval between the sixth and ninth month. The epiphyses for the upper and under surface of the bodies are developed during the interval between the fifteenth and eighteenth year ; and for the auricular and marginal piece, after twenty. The two lower vertebral pieces, although the last to appear, are the first to be completed (between the fourth and fifth year), and unite by their bodies. The union of the bodies takes place from below upwards, and finishes between the twenty-fifth and thirtieth year with the first two pieces. Articulation.—With four bones ; the last lumbar vertebra, ossa innominata, and coccyx. Attachment of Muscles.—To seven pairs ; in front, pyriformis ; on the side, coccygeus ; and behind, gluteus maximus, latissimus dorsi, erector spina), and multifidus spina). The COCCYX ( kokkv£, cuckoo, resembling a cuckoo’s beak) is com- posed of four small pieces, which form the caudal termination of the ver- tebral column. The superior piece is broad, and expands laterally into two transverse processes; it is surmounted by an oval articular surface and two cornua, the former to articulate with the apex of Fig. 92.—Front view of the coccyx. 1, 2, 3, 4. The four pieces of the bone, s, 5. The trans- verse processes of the first piece. 6. Articu- lar surface for the ex- tremity of the sacrum. 7, 7. The cornua which articulate with the sacral cornua. the sacrum, the latter with the sacral cornua. The lateral wings sometimes become connected with the sacrum, and convert the notches for the fifth pair of sacral nerves into foramina. The remaining three pieces diminish in size from above downwards. The borders of the bone are narrow, and give attachment to the coccygeus muscle ; the inferior extremity is rounded, and has at- tached to it the fibres of the external sphincter ani. Development.—By four centres, one for each piece, but, occa- sionally, one of the upper three pieces has an additional centre. Ossification commences in the first piece soon after birth ; in the second, between five and ten years ; in the third, between ten and fifteen ; and in the fourth, between fifteen and twenty. The pieces unite at an earlier period than the bodies of the sacrum, the first two pieces first, then the third and fourth, and lastly the second and third. Between forty and sixty years, the coccyx becomes consoli- dated with the sacrum ; this event taking place later in the female than in the male. Articulations.—With the sacrum. Attachment of Muscles.—To three pairs, and one single muscle ; on each side the coccygeus, behind the gluteus maximus, in front the levator ani, at the tip the sphincter ani. OCCIPITAL BONE. 87 OF THE SKULL. The skull is divisible into two parts, the cranium and the face ; the former being adapted, by its form, structure, and strength, to contain and protect the brain ; the latter, the chief organs of sense. The Cranium is composed of eight separate bones—viz., the Occipital, Two parietal, Frontal, Two temporal, Sphenoid, Ethmoid. OCCIPITAL BONE. Tliis hone is situated at the posterior part and base of the cranium. It is trapezoid in figure, and divisible into two surfaces, four borders, and four angles. External Surface.—Is convex from above downwards and from side to side. Crossing the middle of the bone transversely, from one lateral angle to the other, is a prominent ridge, which, as shown in the diagram, commonly consists of an upper and lower line with a smooth surface between them. The upper is called the highest curved line, and the lower the superior curved line. In the middle of the latter is a projection called the external occipital protuberance, for the attachment of the ligamentum mcchce; and descending from it a small vertical ridge, the external occipital crest. Above and below the superior curved line the surface is rough, for the attachment of muscles. About three-quarters of an inch below the superior curved 88 OCCIPITAL BONE. line is another transverse ridge, the inferior curved line, and beneath the latter the foramen magnum. On each side of the foramen magnum, nearer its anterior than its posterior segment, and encroaching some- what upon the opening, is an oblong articular surface, the condyle, for articulation with the atlas. The condyles approach towards each other anteriorly, their articular surfaces looking downwards and outwards. Directly behind each condyle is an irregular fossa, and, sometimes, a small opening, the posterior condylar foramen, for the transmission of a vein to the lateral sinus. I11 front of the condyle is the anterior condylar foramen, transmitting the hypoglossal nerve ; on the outer side of each condyle, a projecting ridge, the transverse or jugular process, excavated in front by a notch (jugular notch) which forms part of the jugular foramen ; and directly behind the ridge, and forming its posterior boundary, a prominent process, the jugular tubercle. In front of the foramen magnum is a thick square mass, Fig. 93.—External surface of the oc- cipital bone. 1. Superior curved line. 2. External occipital pro- tuberance. 3. External occipital crest. 4. Inferior curved line. 5. Foramen magnum. 6. Condyle of the rieht side. 7. Posterior condylar fossa, in which tbe pos- terior condylar foramen is found. 8. Anterior condylar foramen con- cealed by the margin of the con- dyle. 9. Transverse process; this process on the internal surface of the bone forms the jugular eminence. 10. Jugular notch, forming part of the jugular fora- men. 11. Basilar process. 12. Rough projections into which the odontoid ligaments are inserted. the basilar process, and in its centre a small tubercle, the pharyngeal tubercle or spine, for the attachment of the tendinous raphe and superior and middle constrictor muscles of the pharynx. Internal Surface.—The internal surface is concave from side to side and from above downwards ; it is divided by a crucial ridge into four fossae, the two superior or cerebral fosste lodging the posterior lobes of the cerebrum, the two inferior or cerebellar, the lateral lobes of the cerebellum. The superior arm of the crucial ridge is grooved for the superior longitudinal sinus, and gives attachment to the falx cerebri ; the inferior arm is sharp and prominent for the attachment of the falx cerebelli, and slightly grooved for the two occipital sinuses. The transverse ridge gives attachment to the tentorium cerebelli, and is deeply grooved for the lateral sinuses. At the point of meeting of the four arms is a projection, the internal occipital protuberance. The convergence of the four grooves forms a slightly depressed fossa (usually situated to the right of the internal BASILAR CROOVE PLATE l FO R AM EN MAGNUM. OCCIPITAL BONE 89 occipital protuberance), upon which rests the torcular Herophili. In the centre of the basilar port ion of the bone is the foramen magnum, oblong in form, and larger behind than before, transmitting the spinal cord and its membranes, the spinal accessory nerves, and vertebral and posterior meningeal arteries, and having its anterior constricted portion occupied by the tip of the odontoid process of the axis. Upon the lateral margins of the foramen magnum are two rough eminences, which give attachment to the odontoid ligaments, and immediately above these, the openings of the anterior condylar foramina. In front of the foramen magnum is the basilar process, grooved on its surface for supporting the medulla oblongata, and along eacli lateral border for the inferior petrossal sinus. On each side of the foramen magnum is a groove, for the termination of the lateral sinus ; a smooth surface, which forms part of the jugular Fig. 94.—Internal surface of the occi- pital bone. 1. Left cerebral fossa. 2. Left cerebellar fossa. 3. Groove for the posterior part of the supe- rior longitudinal sinus. 4. Spine for the falx cerebelli, and groove for the occipital sinuses. 5. Groove for the left lateral sinus. 6. In- ternal occipital protuberance. 7. Foramen magnum. 8. Basilar process, grooved tor the medulla oblongata. 9. Termination of the groove for the lateral sinus, bounded externally by the jugular eminence. 10. Jugular fossa : this fossa is completed by the petrous portion of the temporal bone. 12. Superior border. 12. Inferior border. 13. Border which arti- culates with the petrous portion of the temporal bone, grooved by the inferior petrosal sinus. 14. Anterior condylar foramen. fossa ; and a projecting process, which divides the two, and is called the jugular eminence. Into the jugular fossa will he seen opening the posterior condylar foramen. The superior borders are strongly serrated, and assist in forming the lamhdoidal suture; the inferior are rough, not serrated, and articulate with the mastoid portion of the temporal hones. The jugular eminence and side of the basilar process articulate with the petrous portion of the temporal hone, and the intervening space, which is irregularly notched, forms the posterior boundary of the jugular foramen, or foramen lacerum posterius. The angles of the occipital bone are, the superior, inferior, and two lateral. The superior angle is received into the interval formed by the union of the posterior and superior angles of the parietal bones, and corresponds with that portion of the foetal head which is 90 called the posterior fontanelle. The inferior angle is the extremity of the basilar process, which in the adult is united with the sphenoid. The lateral angles, at each side, project into the interval formed by the articulation of the posterior and inferior angle of the parietal with the mastoid portion of the temporal bone. Development.—By seven centres ; four for the four parts of the expanded portion divided by the crucial ridge, one for each condylar part and one for the basilar portion. Ossification commences in the expanded portion of the bone during the eighth week. At birth the bone consists of four distinct pieces, called respectively supra-occipital, two ex-occipitals, and basi-occipital, the division between the basi- occipital and each ex-occipital passing through the anterior third of the condyles. The three first unite during the third or fourth year, the last joins them about the fourth to the sixth year. After twenty- five the basilar process unites with the body of the sphenoid. The part above the occipital protuberances is developed from membrane, the rest from cartilage. Articulations.—With six bones; two parietal, two temporal, sphenoid, and atlas. Attachment of Muscles.—To twelve pairs ; to the superior curved line, the occipito-frontalis, trapezius and sterno-mastoid ; to the rough space between the curved- lines, com plexus, and splenius capitis ; to the space between the inferior curved line and foramen magnum, the rectus posticus major and minor, and obliquus superior ; to the transverse process, the rectus lateralis ; and to the basilar process, the rectus anticus major and minor, and superior and middle con- strictors of the pharynx. PARIETAL BONE. The parietal bone (paries, a wall) is situated at the side and vertex of the skull; it is quadrilateral in form, and divisible into an PARIETAL BONE Fig. 95.—External surface of the left parietal bone. i. Superior orsaggital border. 2. Inferior or squamous border. 3. An- terior or coronal border. 4. Posterior or lambdoidal bor- der. 5. Upper t emporal crest; the figure is situated imme- diately in front of the parietal eminence. 6. The parietal for- amen, unusually large in the bone from which this figure was drawn. 7. Anterior in- ferior angle. 8. Posterior in- ferior angle. external and internal surface, four borders, and four angles. The superior border is straight, to articulate with its fellow of the PARIETAL BONE. opposite side. The inferior border is arched and thin, to articulate with the temporal bone. The anterior border is concave, and the posterior somewhat convex. External Surface.—Crossing the hone in a longitudinal direction frdm the anterior to the posterior border, is an arched line, the tem- poral crest, to which the temporal fascia is attached. Beneath this in well-marked specimens, and separated from it by a very narrow interval, is a second line limiting the attachment of the temporal muscle. In the middle of these lines, and nearly in the centre of the hone, is the projection called the parietal eminence, which marks the centre of ossification. Above the temporal crest the surface is rough, and covered by the aponeurosis of the pccipito-frontalis ; below the crest the bone is smooth, for +he attachment of the fleshy fibres of the temporal muscle. Near the superior border of the bone, and at about one-third from its posterior extremity, is the parietal foramen, which transmits a vein to the superior longitudinal sinus. This foramen is often absent. Internal Surface.—The internal table is smooth; it is marked by numerous furrows, which lodge the ramifications of the middle Fig. 96.—Internal surface of the left parietal bone. 1. Superior, or sagit- tal border. 2. Inferior, or squam- ous border. 3. Anterior, or coronal border. 4. Posterior, or lamb- doidal border. 5. Part of the groove for the superior longitu- dinal sinus. 6. Internal termina- tion of the parietal foramen. 7. Anterior inferior angle of the bone, on which is seen the groove for the trunk of the middle meningeal artery. S. Posterior inferior angle, on which is seen a portion of the groove for the lateral sinus. meningeal artery, and by irregular depressions called digital fossae, which correspond with the convolutions of the brain. Along the upper border is part of a shallow groove, completed by the opposite parietal bone, which serves to contain the superior longitudinal sinus. Near this groove, some slight pits, which lodge the Pacchio- nian bodies, are also observable. The anterior inferior angle is thin and lengthened, and articulates with the tip) of the great wing of the sphenoid bone. Its inner surface is deeply grooved for the middle meningeal artery ; the groove being frequently converted into a closed canal. The posterior inferior angle is thick, and presents a broad and shallow groove for the lateral sinus. FRONTAL BONE. 92 Development.—Ossified in membrane from a single centre which appears in tlie parietal eminence in the seventh week. At the time of birth the superior angles are unossified, and intervals are thus left between the parietal and frontal in front, and the parietal and occipital behind ; these are called the anterior and posterior fonta- nelles. Articulations.—With Jive bones; with the opposite parietal, occipital, frontal, temporal, and sphenoid. Attachment of Muscles.—To one only, the temporal. The aponeurosis of the occipito-frontalis glides over its upper surface. FRONTAL BONE. The frontal bone bears some resemblance in form to the under valve of a scallop-shell. It is situated at the anterior part of the cranium, forming the forehead, and assisting in the construction of the roof of the orbits and nose. Hence it is divisible into a superior or frontal portion, and an inferior or orbito-nasal portion. Each of these portions presents for examination an external and internal surface, borders, and processes. External Surface.—At about the middle of each lateral half of the frontal portion is a projection, the frontal eminence. Below these Fio. 97.—External surface of tlie frontal bone. 1. Situation of the frontal eminence of the right side. 2. Superciliary ridge. 3. Supraorbital ridge. 4. External angular process. 5. Internal angular process. 6. Supraorbital notch, for the transmission of the supra- orbital nerve and artery. 7. Glabella. 8. Temporal crest, commencing from the external angular process (4). 9. Part of the temporal fossa. 10. Nasal spine. points are the superciliary ridges, large towards their inner termina- tion, where they become continuous with the nasal tuberosity, and becoming gradually smaller as they arch outwards: they support the eyebrows. Beneath the superciliary ridges are the sharp and prominent arches which form the upper margin of the orbits, the supraorbital ridges. Externally the supraorbital ridge terminates in the external angular process, internally in the internal angular process; PLATE 2. FRONTAL BONE. 93 at the inner third of this ridge is a notch, sometimes converted into a foramen—the supraorbital notch, which gives passage to the supra- orbital artery, veins, and nerve. Between the two superciliary ridges is a projection, the glabella; this portion of the bone denotes by its prominence the situation of the frontal sinuses. Extending upwards and backwards from the external angular process is a sharp ridge, the commencement of the temporal crest, and beneath the ridge a depressed surface, forming part of the temporal fossa, and giving attachment to the temporal muscle. The orbito-nasal portion of the bone consists of two thin processes, the orbital plates, which form the roof of the orbits, and an interven- ing notch which lodges the ethmoid bone, and is called the ethmoidal fissure. The edges of the ethmoidal fissure are hollowed into cavities, which, by their union with the ethmoid bone, complete the eth- moidal cells. Crossing these edges transversely are two small grooves, which are converted into canals by articulation with the ethmoid : these are the anterior and posterior internal orbital (or ethmoidal) canals; they open on the inner wall of the orbit,—the anterior transmitting the anterior ethmoidal vessels and nasal nerve, the posterior giving passage to the posterior ethmoidal vessels. At the anterior termination of these edges are the irregular openings which lead into the frontal sinuses ; and between the two internal angular processes is a rough excavation which receives the nasal bones, and a projecting process, the nasal spine. On each orbital plate, imme- diately beneath the external angular process, is a shallow depression which lodges the lachrymal gland ; and beneath the internal angular process a small pit (trochlear fossa), sometimes a tubercle, to which the cartilaginous pulley of the superior oblique muscle of the eye is attached. Internal Surface.—Along the middle line of this surface is a grooved ridge, the edges of the ridge giving attachment to the falx cerebri, the groove lodging the superior longitudinal sinus. At the commencement of the ridge is an opening, sometimes completed by the ethmoid bone, the foramen caecum. This opening lodges a process of the dura mater, and occasionally gives passage to a small vein which communicates with the nasal veins. On each side of the vertical ridge are some slight depressions which lodge the Pacchio- nian bodies, and branching grooves for meningeal vessels. There are also numerous shallow depressions called digital fossce, which correspond with the convolutions of the anterior lobes of the cerebrum ; these are especially distinct on the orbital plates. The superior border is thick and strongly serrated, bevelled at the expense of the internal table in the middle, where it rests on the junction of the two parietal, and at the expense of the external table on each side where it receives the lateral pressure of those bones. The inferior border is thin, irregular, and squamous, and articulates with the sphenoid bone. Development.—-By two centres, one for each lateral half, which appear in the orbital arches about the seventh week. The two TEMPORAL RONE. 94 pieces are separate at birth, and unite by suture during the first year, the suture sometimes remaining permanent through life, frontal suture. The frontal sinuses make their appearance during Fig. 98.—Internal surface of the frontal bone ; the bone is raised to show the orbito-nasal portion. 1. Grooved ridge for the lodg. ment of the superior longitu- dinal sinus and attachment of the falx. 2. Foramen caecum. 3. Superior or coronal border of the bone; the figure is situated near that part which is bevelled at the expense of the internal table. 4. Inferior border of the bone, 5. Orbital plate of the left side. 6. Cellular border of the ethmoidal fissure. The fora- men cajcum (2) is seen through the ethmoidal fissure. 7. An- terior and posterior internal or- bital foramen. 8. Nasal spine. 9. The depression for the lach- rymal gland. 10. Depression for the pulley of the superior oblique muscle of the eye ; immediately to the left of this number is the supraorbital notch, and to its right the internal angular pro- cess. 11. Opening leading into the frontal sinuses; the leading line crosses the internal angular process. 12. External angular process. The corresponding parts are seen on the other side of the figure. the seventh year, and increase in size until old age. This bone is entirely developed in membrane. Articulations.—With twelve bones : two parietal, sphenoid, eth- Fig. 99.—Shows articulation of nasal spine of frontal with neighbouring bones. 1. Nasal. 2. Nasal spine of frontal. 3. Nasal process of superior maxillary. 4. Central lamella of ethmoid. 5. Lateral mass of ethmoid. 6. Anterior ethmoidal cell. 7. Superior meatus. moid, two nasal, two superior maxillary, two lachrymal, and two malar. Attachment of Muscles.—To three pairs : corrugator supercilii, to the inner end of the superciliary ridge ; temporal to the temporal fossa ; and orbicularis palpebrarum, to the internal angular process. The temporal hone is situated at the side and base of the skull, and contains in its interior the organ of hearing. It is divisible into a squamous, mastoid, and petrous portion. TEMPORAL BONE. TEMPORAL BONE. 95 The Squamous portion (squama, a scale), forming the anterior part of the bone, is thin, translucent, and contains no diploe. On its external surface it is smooth, gives attachment to the fleshy fibres of the temporal muscle, and is marked by a small groove running almost vertically upwards, for the posterior deep temporal artery. It has projecting from it an arched and lengthened process, the zygoma (from £vyos,' a yoke, because it joins the temporal and malar bones together), which, as it passes forwards, becomes twisted in itself. Near the commencement of the zygoma, upon its lower border, is a projection called the tubercle, to which is attached the external lateral ligament of the lower jaw, and continued horizontally in- wards from the tubercle, a rounded eminence, the eminentia articu- laris. The process of bone which is continued from the tubercle of the zygoma into the eminentia articularis is the inferior root of the zygoma. The superior root is continued upwards from the upper Fig. ioo.—External surface of the temporal bone of the left side, i. Squamous portion. 2. Mastoid portion. 3. Extremity of the pet- rous portion. 4. The zygoma. 5. Indicates the tubercle of the zygoma, and at the same time its anterior root turning inwards to form the eminentia articularis. 6. Superior root of the zygoma, forming the posterior part of the temporal crest. 7. Middle root of the zygoma, terminating abruptly at the glenoid fossa. 8. Mastoid foramen. 9. External auditory meatus, surrounded by the audi- tory process. 10. The digastric fossa, situated immediately to the inner side of (2) the mas- toid process. 11. Styloid process. 12. Vaginal process. 13. Fissure of Glaser; the leading line from this number crosses the rough posterior portion of the glenoid fossa. 14. The opening and part of the groove for the Eustachian tube. border of the zygoma, and forms the posterior part of the temporal crest (supra-mastoil crest), serving by its projection to mark the division of the squamous from the mastoid portion of the bone ; and the middle root, called also post-glenoid process, passes inwards and backwards, and terminates abruptly at a narrow fissure, the fissure of Glaser. The upper border of the zygoma is thin and l sharp, and has attached to it the fibres of the temporal fascia ; the lower border is thick, and gives origin to some fibres of the masseter muscle. The internal surface of the squamous portion is marked by : several shallow fossae, which correspond with the convolutions of the ; cerebrum, and by a furrow for the posterior branch of the middle meningeal artery. The superior or squamous border is very thin, and bevelled at the expense of the inner surface, so as to overlap the lower and arched border of the parietal bone. The inferior border 1 is thick, and dentated to articulate with the spinous process of the sphenoid bone. TEMPORAL BONE. 96 The Mastoid portion (yaaros elbos, nipple-like) forms the posterior part of the bone ; it is thick and hollowed between its tables into numerous cavities. Those situated near the apex and back part of the bone are small and generally filled with marrow ; the upper and anterior cavities, much larger in size, contain air, and are in com- munication with the tympanic cavity. One of the latter, larger and more constant than the rest, is named the mastoid antrum,. On its external surface the mastoid portion is rough for the attachment of muscles, and near the posterior border of the bone is an irregular opening, sometimes large, and sometimes so small as to be almost indistinguishable, called the mastoid foramen, which transmits a vein to the lateral sinus, and a small artery to the dura mater. The inferior part of the mastoid portion is round and expanded, the mastoid process. Directly to the inner side of, and partly concealed by it, is a deep groove, the digastric fossa, for the digastric muscle, and a little more internally the occipital groove, which lodges the occipital artery, a branch of the external carotid. On its internal surface the mastoid portion presents a broad and shallow groove (fossa sigmoidea) for the lateral sinus, and terminating in this groove the internal opening of the mastoid foramen. The superior border of the mastoid Fig. ioi.—Section of the temporal bone, right side, showing the curved direction of the external audi- tory meatus, i. Edge of the auditory process. 2. Groove into which the membrana tympani is inserted. The obliquity of the line from 2 to 3 indicates the oblique termination of the meatus, and the consequent oblique direction of themem- brani tympani. 4, 4. Cavity of the tympanum. 5. Opening of the Eustachian tube. 6. Part of the aquaeductus Fallopii. 7. Part of carotid canal. portion is dentated, and articulates with the posterior inferior angle of the parietal bone ; its posterior border is thick, and less serrated, and articulates with the inferior border of the occipital bone. The external auditory meatus is a slightly curved canal, about half an inch in length, and rather longer on its floor than on its roof; it is narrower in the middle than at either end, and is broadest in its horizontal diameter, and terminates at the outer wall of the tympanum by an abrupt oval border. Within the margin of this border is a groove for the insertion of the membrani tympani. The Petrous portion of the temporal bone is named from its extreme hardness and density (nerpos, a rock). It is a three-sided pyramid, projecting horizontally forwards into the base of the skull, the base being partly applied against the internal surface of the squamous and mastoid portions, and partly exposed as the opening of the ear ; its apex is received into the triangular interval between the spinous process of the sphenoid and the basilar process of the occipital bone. For convenience of description it is divisible into base, apex, three surfaces, anterior, posterior, and basilar; and three borders, superior, anterior, and posterior. The base is pierced by the external auditory meatus, surrounded by a rough process of bone, tbe auditory process, which, when traced backwards, is seen to be continuous with the bone ensheathing the styloid process. The apex of the petrous bone is pierced by the inner opening of the carotid canal, and forms the posterior and external boundary of the middle lacerated foramen. The anterior surface, forming the back part of the middle fossa of the base of the skull, presents from base to apex, firstly, a slight depression, which corresponds to the position of the roof of the tympanic cavity ; next, an eminence caused by the projection of the superior semicircular canal; thirdly, a groove leading to an irregular oblique opening, the hiatus Fallopii, for the transmission of the petrosal branch of the Vidian nerve ; another and smaller oblique foramen, immediately beneath the preceding, for the passage of the lesser petrosal nerve ; and lastly, near the apex of the bone, a depression for the Gasserian ganglion. The posterior surface forms the front of the posterior fossa of the skull; near its middle is the oblique entrance of the meatus auditorius intertills, which gives passage to the seventh and eighth nerves and the auditory artery. Above the meatus auditorius in- ternus is a small oblique fissure, and a minute fora- men ; the former lodges a process of the dura mater, and the foramen gives passage to a small vein. Further out- wards, towards the mastoid portion of the bone, is a small slit, almost hidden by a thin plate of bone ; this is the ac/uceductus vestibuli, and transmits a small artery and vein of the vestibule and a process of dura mater. Below the meatus, and partly concealed by the margin of the posterior border of the bone, is a triangular opening, the termination of the aqucedudus cochlea, through which passes a vein from the cochlea to the inferior petrosal sinus, and a process of dura mater. TEMPORAL PONE. 97 Fig. 102.—Right temporal bone, seen from below, i. Squamous portion. 2. Mastoid portion. 3. Petrous portion. 4. Zygoma. 5. Tubercle of the zygoma. 6. Articular eminence. 7. Glenoid fossa. 8. Glaserian fissure. 9. External auditory meatus. 10. Styloid process, n. Digastric fossa. 12. Occipital groove. 13. Stylo-mastoid foramen. 14. Jugular fossa. 15. Foramen for Jacobson’s nerve. 16. Jugular notch. 17. Aquaeductus cochleae. 18, 18. Carotid canal. 19. Canals for the tensor tympani muscle and Eusta- chian tube. 20. Mastoid foramen. 98 TEMPORAL BONE. The basilar surface of the petrous portion is rough, irregular, and enters into the formation of the under surface of the base of the skull. Projecting downwards, near its middle, is a long sharp spine, the styloid process, occasionally connected with the bone only by cartilage, and lost during maceration, particularly in the young subject. At the base of this process is a rough sheath-like ridge, into which the styloid process appears implanted, the vaginal process or tympanic lamina ; it is continuous externally with the auditory process. In front of the vaginal process is a broad triangular depression, the glenoid fossa, bounded in front by the eminentia articularis, behind by the vaginal process, and externally by the rough lip of the audi- tory process. The glenoid fossa (yKrjvy, a socket) is divided transversely by the Flo. 103.—Left temporal bone, seen from within. 1. Squamous portion. 2. Mastoid portion. The figure is placed immediately above the inner opening of the mastoid foramen. 3. Petrous portion. 4. Groove for the posterior branch of the middle meningeal artery. 5. Bevelled edge of the squamous border of the bone. 6. Zygoma. 7. Digastric fossa, im- mediately internal to the mastoid process. 8. Occipital groove. 9. Groove for the lateral sinus. 10. Elevation on the anterior surface of the petrous bone, marking the situation of the perpendicular semi- circular canal. 11. Opening of ter- mination of the carotid canal. 12. Meatus auditorius interims. 13. A dotted line leads upwards from this figure to the narrow fissure which lodges a process of the dura mater. Another line leads downwards to the sharp edge which conceals the open- ing of the aquaeductus cochleae, while the cipher itself is situated on the bony lamina which overlies the opening of the aqumduotus vestibuli. 14. Styloid process. 15. Stylo-mastoid foramen. 16. Carotid foramen. 17. ,1 ugular process. The deep ex- cavation to the left of this forms part of the jugular fossa ; that to the right is the groove for the ninth, tenth, and eleventh pairs of nerves. 18. Notch for the fifth nerve on the upper border of the petrous bone, near its apex. 19. Extremity of the petrous bone, giving origin to the levator palati and tensor tympani muscle. fissure of Glaser, which is the line of union between the tympanic and squamous portions of the temporal hone ; it receives the ex- tremity of the processus gracilis of the malleus, and transmits the laxator tympani muscle, and anterior tympanic artery. At the inner extremity of the fissure a minute canal terminates, canal of Huguier; it transmits the chorda tympani nerve. The surface of the fossa in front of the fissure is smooth, to articulate with the condyle of the lower jaw ; and that behind the fissure rough, for the reception of part of the parotid gland. At the extremity of the inner angle of the glenoid fossa is the opening of the Eustachian tube; above this, and separated from it by a thin lamella of bone, called processus coch- learifortnis, is a small canal for the transmission of the tensor tympani muscle. PLATE 3. Occipito- frontalis. TEMPORAL BONE. 99 Directly behind, and at the root of the styloid process, is the stylo- mastoid foramen, the opening of exit of the facial nerve, and entrance of the stylo-mastoid artery ; and a little in front of this, between the mastoid and vaginal processes, is a small slit, the auricular fissure, for the exit of the auricular branch of the pneumogastric (Arnold’s nerve). Midway between the styloid process and apex of the bone is a large oval opening, the foramen of entrance of the internal carotid artery and carotid plexus of nerves into the carotid canal. Between the stylo-mastoid and carotid foramen, in the posterior border, is an irregular excavation forming part of the jugular fossa for the commencement of the internal jugular vein, on the inner wall of which will be found a minute foramen, for the entrance of Arnold’s nerve. The share of the jugular fossa formed by the petrous portion of the temporal bone is different in different bones ; but in all the fossa presents a vertical ridge on its inner side, which cuts off a small portion from the rest. The upper part of this ridge forms a spinous projection, the jugular process; the groove to the inner side of the ridge lodges the ninth, tenth, and eleventh nerves, and the lower part of the ridge is the septum of division between the jugular fossa and carotid foramen. Upon the latter portion of the ridge, near the posterior margin of the carotid foramen, is a small opening leading into a canal which transmits the tympanic branch of the glosso-pliaryngeal nerve (Jacobson’s nerve). The superior border of the petrous portion is sharp, and gives attachment to the tentorium cerebellL It is grooved for the superior petrosal sinus, and near its extremity is marked by a smooth notch, upon which reclines the fifth nerve. The anterior border is grooved for the Eustachian tube, and forms the posterior boundary of the foramen lacerum basis cranii ; by its sharp extremity it gives attach- ment to the tensor tympani, and levator palati muscle. The 'pos- terior border is grooved for the inferior petrosal sinus, and excavated for the jugular fossa : it forms the anterior boundary of the jugular foramen. Development.—The temporal bone is developed in four portions, the squamo-zygomatic, tympanic, petro-mastoid (or periotic), and styloid. Ossification commences in the squamo-zygomatic portion about the seventh week. In the third month ossific deposits appear in the floor of the outer wall of the tympanum, and extending upwards form a circle, the tympanic ring, which is defective above ; it joins the squamo- zygomatic portion in the ninth month. In the petro- mastoid portion ossification begins in the fifth month, taking place by four distinct osseous deposits ; one for the promontory (opisthotic), one for the greater part of the petrous bone seen in the base of the skull (prootic), a third in connection with the posterior semicircular canal and lower part of the mastoid (epiotic), and a fourth forming the roof of the tympanum and covering of the external semicircular canal (pt erotic); these centres all fuse by the end of the sixth month. Fig. 104.—The tympanic ring of the foetal skull, right side. SPHENOID BONE. The styloid process is commonly formed by two osseous deposits, one (the tympuno-hyal) at the base, before birth ; the other (stylo-kyal) at the tip, after birth ; the latter often remains separate during the whole of life. The squamo-zvgomatic portion is developed from membrane, the other portions from cartilage. At the time of birth the temporal bone consists of three pieces ; the mastoid antrum is present, hut the mastoid cells do not commence to be formed till the ninth year. From the above description it will be seen that the total number of centres of ossification is eight. Articulations.—With Jive bones: occipital, parietal, sphenoid, inferior maxillary, and malar. Attachment of Muscles.—To fourteen: by the squamous portion, to the temporal; by the zygoma, to the masseter ; by the mastoid portion, to the occipito-frontalis, splenius capitis, sterno-mastoid, trachelo-mastoid, digastricus, and retrahens auriculam; by the styloid process, to the stvlo-pharyngeus, stylo-hyoid, stylo-glossus, and two ligaments, stylo-hyoid and stylo-maxillary ; and by the petrous portion, to the levator palati, tensor tympani, and stapedius. SPHENOID BONE. The sphenoid (af>r)v, a wedge) is an irregular hone, situated at the base of the skull, wedged between the other hones of the cranium, and entering into the formation of the cranium, orbits, and nasal fossae. It bears some resemblance, in form, to a bat with its wings extended, and is divisible into body, wings, and processes. The body forms the central mass of the bone, from which the wings and processes are projected. From the upper and anterior part of the body extend, one to each side, two small triangular plates, the lesser wings; from each side, and expanding laterally, are the greater wings; proceeding backwards from the base of the greater wings, the spinous processes, and downwards, the pterygoid processes. The body presents for examination a superior or cerebral surface, an antero-inferior surface, and a posterior surface. Superior Surface.—At the anterior extremity of this surface is a small projecting plate, the ethmoidal spine, which articulates with the cribriform plate of the ethmoid ; and spreading out on each side the lesser wings. Behind the ethmoidal spine in the middle line is a shallow transverse groove which lodges the optic commissure; behind this is a rounded elevation, the olivary process; and on each side of the posterior margin of that process a tubercle, the middle clinoid process (kXIvtj, a bed). Passing outwards and forwards from the groove just mentioned are the optic foramina, which transmit the optic nerves and ophthalmic arteries. Behind the optic foramina are two sharp tubercles, the anterior clinoid processes, which are the inner terminations of the lesser wings. Beneath these processes, on the sides of the olivary process, are two depressions for the last turn of the internal carotid arteries ; they are often converted into foramina (carotico-clinoid) by a spicule of bone uniting tlie anterior and middle cl in oid processes. Behind the olivary process is the sella turcica, the deep fossa which lodges the pituitary gland and circular sinus ; behind and somewhat overhanging the sella turcica, is a broad rough plate, dorsum sellce, bounded at each angle by a tubercle, the 'posterior clinoid processes; and behind this plate an inclined surface (clivus Blumenbachii), which is continuous with the basilar process of the occipital bone, and supports the Pons Varolii. On each side of the sella turcica is a broad groove (carotid or cavernous groove); it is bounded externally at its back part by a well-marked ridge called the lingula sphenoidalis. The carotid groove lodges the internal carotid artery, cavernous sinus, orbital nerves, and cavernous plexus of the sympathetic. Opposite the middle of the sella turcica the SPHENOID BONE. 101 Fig. 105.—Superior or cere- bral surface of the sphen- oid bone. 1. Olivary pro- cess. 2. Ethmoidalspine. 3. Lesser wing of the left side. 4. Cerebral surface of the greater wing of the same side. 5. Spinous process. 6. Extremity ot' the ptery- goid process, project- ing downwards from the under surface of the body of the bone. 7. Optic foramen. 8. An- terior clinoid process. 9. Carotid or cavernous groove. 10. Sella turcica; the two tubercles in front of the figure are the middle cimoid processes. 11. Dorsum sellse; its projecting angles are the posterior clinoid processes. 12. Basilar portion of the bone. 13. Part of the sphenoidal fissure. 14. Foramen rotundum. 15. Foramen ovale. 16. Foramen spi nosum. 17. The angular interval which receives the apex of the petrous portion of the temporal bone. The posterior extremity of the Vidian canal terminates at this angle. t8. Spine of the spinous process. 19. The border of the greater wing which articulates with the squamous portion ot the temporal bone. 20. The internal border of the spinous process, which assists in the formation of the foramen laeerum basis cranii. 21. fhat portion of the greater wing which articulates with the anterior inferior angle ot the parietal bone. 22. The portion of the greater wing which articulates with the orbital process of the frontal bone. groove is single, but as it passes backwards it divides into two portions, which are separated by a projecting ridge, springing from the lower part of the dorsum sella) (superior petrosal process'). The upper groove lodges the cavernous sinus and orbital nerves, and the lower the carotid artery and carotid plexus of nerves. Upon the anteroinferior surface of the body of the sphenoid is a long flattened spine or crest, the superior part of which sphenoidal crest articulates with the central lamella of the ethmoid, while the inferior part, longer and sharper, the rostrum, is inserted into the sheath formed by the upper border of the vomer. On each side of the _ sphenoidal crest is an irregular opening leading into the sphenoidal cells. rI he sphenoidal cells, absent in the young subject, are divided by a median septum which is continuous with the crest, 102 SPHENOID BONE. and are partially closed by two thin plates of bone (frequently broken away), the sphenoidal spongy bones (bones of Bertin). On each side of the sphenoidal cells are the outlets of the optic forandna, and other openings to be presently described ; the lesser and greater wings ; and, below, the pterygoid processes. At the under surface of the body are two thin plates of bone (vaginal processes), proceeding from the base of the pterygoid process at each side, articulating with the a he of the vomer. On each of these plates, close to the root of the pterygoid process, is a groove converted into a canal by the palate bone, the pterygo-palatine canal for the pterygo-palatine nerve and pharyngeal artery ; and traversing the root of the pterygoid process at its union with the body of the bone, is the pterygoid or Vidian, canal, which gives passage to the Vidian nerve and artery. The posterior surface of the body is flat and rough, and articu- lates with the basilar process of the occipital bone ; after the twenty- fifth year this union is usually completed by bone. The posterior surface is continuous at each side with the spinous process, and in the angle of union is the termination of the Vidian canal. The lesser wings (orbito-sphenoids) are thin and triangular, the base being attached to the upper and anterior part of the body of the sphenoid ; and the apex, prolonged outwards, terminating in an Fig. 106.—Anteroinferior view of the sphenoid bone. i. Eth- moidal spine. 2. The rostrum. 3. Sphenoidal spongy bone partly closing the left opening of the sphenoidal cells. 4. Les- ser wing. 5. Optie foramen, piercing the base of the lesser wing. 6. Sphenoidal fissure. 7. Foramen rotundum. 8. Or- bital surface of the greater wing. 9. Its temporal sur- face. 10. The pterygoid ridge. 11. Pterygo- palatine canal. 12. Foramen of entrance of the Vidian canal. 13. Internal pterygoid plate. 14. Hamular process. 15. External pterygoid plate. 16. Fora- men spinosum. 17. Foramen ovale. 18. Extremity of the spinous process of the sphenoid. acute point. The anterior border, irregularly serrated, articulates with the orbital plate of the frontal; the posterior, free and rounded, is received into the fissure of Sylvius of the cerebrum. The inner extremity of this border is the anterior clinoid process ; it is sup- ported by a short pillar of bone, which forms the inferior boundary of the optic foramen, and gives attachment by its anterior surface to part of the common tendon of the muscles of the orbit. The lesser wing forms the posterior part of the roof of the orbit. Between the lesser and greater wings is a triangular slit, broad internally, but narrowing almost to a point at its outer extremity—this is the sphenoidal fissure (foramen lacerum anterius) ; it transmits the third, fourth, three branches of the ophthalmic division of the fifth, the PLATE 4. Sphenoidal fissure Posterior clinoid process. Levator palpebrre. Superior rectus. Superior oblique. Upper head of ext. rectus. Lower head of ext. rectus. Internal rectus. Inferior rectus. Additional origin of external rectus. Foramen rotundum. For. ovale. Foramen spinosum. Spinous process. ' Laxator tympani. SPHENOID BONE. 103 sixth nerves, and some branches from the cavernous plexus of the sympathetic, with the ophthalmic vein. The greater wings (alee-sphenoids) present three surfaces; a superior or cerebral, which forms part of the middle fossa of the base of the skull; an anterior surface, which assists in forming the outer wall of the orbit; and an external surface, divided into two parts by the pterygoid ridge. The superior surface is concave, and receives the anterior part of the temporo-sphenoidal lobe of the cerebrum ; at its internal border, where the greater wing joins the body, and immediately behind the sphenoidal fissure, is a circular opening, foramen rotundum, through which passes the superior maxillary branch of the fifth nerve. Behind and external to this, is a large foramen called foramen ovale; it transmits the inferior maxillary division of the fifth nerve, the small meningeal artery, and lesser petrosal nerve. At the inner side of the foramen ovale a small opening is sometimes found ; it is the foramen Vesalii, and transmits a small vein. The anterior or orbital surface looks into the orbit; it is quadrilateral in shape, and its posterior border, which bounds the sphenoidal fissure interiorly, is usually marked by a slight pro- minence, for the attachment of part of the external rectus muscle ; its inferior edge forms the outer boundary of the spheno-maxillary fissure ; its outer edge is rough for articulation with the malar bone. The superior part of the external surface enters into the formation of the temporal fossa, the inferior portion forms part of the zygomatic fossa. The pterygoid ridge, dividing the two, gives attachment to the upper origin of the pterygoideus externus muscle. The spinous processes are the posterior terminations of the greater wings; they project backwards, and are received into the angular interval between the squamous and petrous portions of the temporal bones. Near its apex each process is pierced by a small opening, foramen spinosum, for the middle meningeal vessels, and extending downwards from the apex is a short spine, which gives attachment to the long internal lateral ligament of the lower jaw, and to the laxator tympani muscle. The external border of the spinous process is rough, to articulate with the lower border of the squamous portion of the temporal bone ; the internal border forms the anterior boundary of the foramen lacerum basis cranii, and is somewhat grooved for the reception of the Eustachian tube. The pterygoid processes descend perpendicularly from the base of the greater wings, and form in the articulated skull the lateral boundaries of the posterior nares. Each process consists of an ex- ternal and internal plate, partly united in front, but divergent behind, so as to enclose a space called the pterygoid fossa, and sepa- rated below by an interval, the pterygoid notch, which receives the tuberosity of the palate bone. The external plate is broad and thin, giving attachment, by its external surface, to the external pterygoid muscle, and by its internal surface to tire internal pterygoid. The interned pterygoid plate is long and narrow, terminating at its extre- mity by a curved hook, the hamular process, around which plays the 104 tendon of the tensor palati muscle, and to the tip of which the pterygo-maxillary ligament is attached ; while from the lower third of its posterior border some fibres of the superior constrictor muscle of the pharynx have their origin. At the base of the internal pterygoid plate is a small oblong depression, the scaphoid or navicular fossa, from which arises the circumflexus or tensor palati muscle. The anterior surface of the pterygoid process is broad near its base ; it forms the posterior wall of the spheno-maxillary fossa, and sup- ports Meckel’s ganglion. At its lower part this surface is slightly grooved, to form part of the descending palatine canal. The base of the pterygoid process is pierced by the Vidian canal. Development.—Up to the seventh or eighth month of intra- uterine existence, the anterior and posterior parts of the body of the sphenoid are distinct from each other ;—the anterior part, extending from the posterior border of the olivary process to the ethmoidal spine, being called pre-sphenoid, and the posterior portion, from the border of the olivary process to the spheno-occipital synchondrosis, the post-sphenoid. The sphenoid is developed by fourteen centres of ossification, four for the pre-sphenoid, six for the post-sphenoid, two for the internal pterygoid plates, and two for the sphenoidal spongy bones. The first' pre-splxenoidal centres appear at the outer side of the optic foramina, about the eighth or ninth week. These are soon followed by another pair of centres, placed to the inner side of the optic fora- mina. From these four centres the anterior part of the body of the sphenoid and the lesser wings are developed. About the eighth week ossitic nuclei appear in the greater wings (ali-sphenoids) between the foramen ovale and rotundum. From tliis point ossification ex- tends into the whole of the great wing and the external pterygoid plate. In the eighth week also, or a little later, two centres appear in the post-sphenoidal portion of the body (basi-sphenoids), placed side by side in the bottom of the sella turcica. These unite about: the fourth month, and after their union two new centres spring up at the other side of the carotid groove, and form the lingula (splien- otics). The centres for the internal pterygoid processes appear about the fourth month, and they unite with the external pterygoid about the sixth month. The sphenoidal spongy bones do not become ossified till after birth; they join the rest of the bone at the time of puberty. At the time of birth the sphenoid consists of three pieces—the body in the centre, and on each side the great wings with the ex- ternal pterygoid plates. They unite during the first year. The sphenoidal cells first begin to appear at about seven years of age. The sphenoid joins the occipital from the eighteenth to the twenty- fifth year. Articulations.—With twelve bones: that is, with all the bones of the cranium, and five of the face—viz., two malar, two palate, and vomer. Attachment of Muscles.—To twelve pairs: temporal, external SPHENOID BONE. ETHMOID BONE. pterygoid, internal pterygoid, superior constrictor, tensor palati, laxator tympani, levator palpebrse, obliquus superior, superior rectus, internal rectus, inferior rectus, and external rectus. ETHMOID BONE. The ethmoid (rjdfios, a sieve) is a square-shaped cellular bone, situated between the two orbits, at the root of the nose, and per- forated on its upper surface by a number of small openings, from which peculiarity it has received its name. It consists of a horizontal plate, a perpendicular lamella, and two lateral masses. The horizontal or cribriform plate connects the lateral masses with the perpendicular lamella, and is situated on the upper aspect of the bone. It is hollowed into two shallow grooves (olfactory grooves) which support the olfactory bulbs, and is pierced by numerous fora- mina, for the filaments of the olfactory nerve. I11 the middle of each groove the foramina pierce the bone completely, but at the sides the openings communicate with minute canals which run in the sides of the central lamella, the lateral masses and turbinated bones. At the anterior extremity of the cribriform plate are two narrow slits, for the nasal branch of the fifth nerve ; its posterior border articu- lates with the ethmoidal spine of the sphenoid. The perpendicular lamella is a thin central plate, which articu- lates by its anterior border with the frontal spine and crest of the Fig. 107.—Ethmoid bone seen from above and be- hind. x. Perpendicular lamella. 2, 2. Lateral masses ; the figures are placed on the posterior border of the lateral mass at each side. 3. Crista galli. 4. Cribriform plate of the left side, pierced by its foramina. 5. Thehollowspaceimmediately above and to the left of this number is the supe- rior meatus. 6. Superior turbinated bone. 7. Middle turbinated bone; the numbers, 5, 6, 7, are situated on the internal surface of the left lateral mass, near its posterior parts. 8. External surface of the lateral mass, or os planum. 9. Superior or frontal border of the lateral mass, grooved by the anterior and posterior internal orbital canals. 10. Refers to the concavity of the middle turbinated bone, which is the tipper boundary of the middle meatus. 11. Unciform process. nasal bones, and by its posterior border with the crest of the sphenoid and upper edge of the vomer. Its inferior border is broad and bilaminar ; it articulates with the septal cartilage of the nose. It is surmounted superiorly by a thick and strong process, the crista galli, which projects into the cavity of the skull, and gives attachment to the falx cerebri. From the base of the anterior border of this process there project forward two small plates, alar processes, which are re- ceived into corresponding depressions in the frontal bone, and often complete posteriorly the foramen caecum. That portion of the per- pendicular plate which lies below the level of the cribriform plate assists in forming the septum of the nose. 106 ETHMOID BONE. The lateral masses or labyrinths are divisible into an internal and external surface, and four borders, superior, inferior, anterior, and posterior. The internal surface is rough, slightly convex, and forms the external boundary of the upper part of the nasal fossae. Towards the posterior border of this surface is a narrow horizontal fissure, the superior meatus of the nose ; the upper margin of this fissure is thin, and somewhat curled inwards ; hence it is named the superior turbinated bone. Below the meatus is the convex surface of another thin plate, which is curled outwards, and forms the lower border of the mass, the middle turbinated bone. The external surface is quadrilateral and smooth ; lienee it is named os planum; it enters into the formation of the inner wall of the orbit. The superior border is uneven and cellular, the cells being com- pleted by the edges of the ethmoidal fissure of the frontal bone. This border is crossed by two grooves, sometimes complete canals, opening into the orbit by the anterior and posterior internal orbital foramina. The inferior border is formed internally by the lower border of the middle turbinated bone, and externally by a concave irregular fossa, the upper boundary of the middle meatus. The anterior border presents a number of incomplete cells, which are closed by the superior maxillary and lachrymal bones ; the posterior border is irregularly cellular, to articulate with the sphenoid and palate bone. From the anterior part of each lateral mass an irre- gular plate of hone descends backwards, terminating in a hook-like extremity : this is called the unciform process. It assists in closing the orifice of the antrum, and articulates with the ethmoidal pro- cess of the inferior turbinated bone. The lateral masses are composed of cells, divided by a thin par- tition into anterior and posterior ethmoidal cells. The anterior, the most numerous, communicate with the frontal sinuses, and open by means of an irregular and incomplete tubular canal, the infundi- bulum, into the middle meatus. The posterior cells, fewer in number, open into the superior meatus. Development.—By three centres : one for each lateral mass, and one for the perpendicular lamella. Ossification commences in the lateral masses at about the beginning of the fifth month, appearing first in the os planum, and then in the turbinated bones. At birth the bone merely consists of two ill-developed lateral masses. During the latter half of the first year after birth, the central lamella and cribriform plate begin to ossify, and are united to the lateral masses by the beginning of the second year. The cells of the ethmoid are developed in the course of the fourth and fifth year. Articulations.—With thirteen bones : two of the cranium, frontal and sphenoid ; and eleven of the face, viz., two nasal, two superior maxillary, two lachrymal, two palate, two inferior turbinated, and vomer. No muscles are attached to this bone. NASAL BONES. 107 BONES OF THE FACE. The face is composed of fourteen bones—namely, Two nasal, Two superior maxillary, Two lachrymal, Two malar, Two palate, Two inferior turbinated, Vomer, Inferior maxillary. The nasal are two small quadrangular hones, forming by their union the bridge and base of the nose. They are convex on their outer surface, and pierced by a foramen for a small vein ; on the inner surface they are somewhat concave, and marked by a groove which lodges the nasal branch of the ophthalmic nerve. The superior border is narrow and thick ; the inferior broad, thin, and irregular. The anterior border, thick above and thin below, articulates with the bone of the opposite side. The external border is thin and irregular; it is bevelled at the expense of the inner surface above, and of the outer surface below, and articulates with the nasal process of the superior maxillary. Development.—By a single centre for each bone, ossification com- mencing in the seventh week. Articulations.—With four bones: frontal, ethmoid, nasal, and superior maxi 11 ary. Attachment of Muscles.—It has in relation with it the pyrami- dalis nasi and compressor nasi; but neither is inserted into it. NASAL BONES. Fig. 108.—Nasal bone of the left side; its external or convex surface, i. Superior border. 2. Internal or mesial border. 3. External border. 4. Inferior or free border. 5. Fora- men for a small vein. The superior maxillary are the largest hones of the face, with the exception of the lower jaw; they, form, by their union, the whole of the upper jaw, and assist in the construction of the nose, orbit, cheek, and palate. Each bone is divisible into a body and four processes. The body is triangular in form, and hollowed in its interior into a large cavity, the antrum maxillare (antrum of Highmore). It presents for examination four surfaces, external or facial, internal or nasal, posterior or zygomatic, and superior or orbital. The external or facial surface forms the anterior part of the SUPERIOR MAXILLARY BONES. 108 SUPERIOR MAXILLARY BONES. bone; it presents a deep depression towards its centre, the canine fossa, which gives attachment to the levator anguli oris muscle. Immediately above this fossa is the infraorbital foramen, the termina- tion of the infraorbital canal, transmitting the infraorbital nerve and artery ; and above the infraorbital foramen is the lower margin of the orbit, continuous externally with the rough articular surface of the malar process, and internally with a thick ascending plate, the nasal process. Between the infraorbital foramen and the margin of the orbit, the levator labii superioris proprius muscle has its origin. Towards the middle line of the face the external surface is bounded by the concave border of the opening of the nose ; this border is projected forwards at its inferior termination into a sharp process, forming, with a similar process of the opposite bone, the nasal spine. Beneath the nasal spine, and above the two superior incisor teeth, is a slight depression, the incisive or myrtiform fossa, which gives origin to the depressor labii superioris alaigue nasi muscle. Above and a Fig. 109.—Superior maxillary bone of the right side, as seen on its lateral aspect. 1. External or facial surface; the depression in which the cipher is placed is the canine fossa. 2. Posterior, or zygomatic sur- face. 3. Superior or orbital surface. 4. Infra- orbital foramen, situated immediately below the cipher. 5. Infraorbital canal, leading to the infra- orbital foramen. 6. Inferior border of the orbit. 7. Malar process. 8. Nasal process. 9. Lateral boundary of the anterior nares. 10. Nasal spine. 11. Incisive or myrtiform fossa. 12. Alveolar pro- cess. 13. The internal border of the orbital surface, which articulates with the ethmoid and palate bone. 14. Concavity which articulates with the lachrymal bone, and forms the commencement of the nasal duct. 15. Nasal crest of the palate process, i. Two incisor teeth, c. Canine. 6. Two bicuspid teeth. m. Three molars. little to the outer side of the fossa the compressor nasi lias its origin. The myrtiform fossa is divided from the canine fossa by a perpen- dicular ridge {canine ridge) corresponding with the root of the canine tooth. The inferior boundary of the facial surface is the alveolar process which contains the teeth of the upper jaw ; and the facial is separated from the zygomatic surface by a strong projecting eminence, the malar process. The internal or nasal surface presents a large irregular opening, leading into the antrum ; this opening is nearly closed in the articu- lated skull by the ethmoid, palate, lachrymal, and inferior turbi- nated bone. In front of the opening of the antrum is the strong ascending plate of the nasal process, marked interiorly by a rough horizontal ridge, inferior turbinal crest, which gives attachment to the inferior turbinated bone. The concave depression immediately above this ridge corresponds with the middle meatus of the uose, that below the ridge with the inferior meatus. Between the nasal process and the opening of the antrum is a deep vertical groove, PLATE 5 Orbic. palp Nasal process Lev. lab. sup. alasque nasi Lev. proprius Compressor nasi. . Laclirjmal groove. / Inf. oblique. — Infraorbital canal. Zygomatic process. Depressor alas nasi. Anterior palatine canal. _ Incisive foramen. - Anterior naso-palatine canal Anterior palatine canal. Posterior naso-palatine canal. Sup. turbinal crest. Middle meatus Inf. turbinal crest Ant. palat. canal. Djsc. pal at. canal. Incisive foramen, SUPERIOR MAXILLARY BONES. converted into a canal by the lachrymal and inferior turbinated bone, and constituting the nasal duct. The superior border of the nasal surface is irregularly cellular, and articulates with the lachrymal and ethmoid bones ; the posterior border is rough, and articulates with the palate bone; it is marked by a narrow groove, nearly vertical in direction, which forms part of the descending palatine canal; the anterior border is sharp, and forms the free margin of the opening of the nose, and, from the inferior border, projects inwards a strong horizontal plate, the palate process. The Antrum of Highmore or maxillary sinus is an irregular four-sided cavity with thin walls ; the outer wall being formed by the facial portion of the bone, the posterior by the zygomatic process, the roof by the orbital process, and the inner wall by the nasal surface of the bone, the unciform process of the ethmoid, the palate, lachrymal and inferior turbinated. Its floor is rendered Fig. ho.—Right superior maxillary bone; inter- nal surface, i. Antrum. 2. Nasal process. 3. Superior turbinal crest. 4. Depression cor- responding with the middle meatus. 5. In- ferior turbinal crest. 6, 6. Inferior meatus. 7. Nasal duct. 8. Notch for articulation with the lachrymal bone. 9. Superior border of the bone, in which are seen three ethmoidal cells. 10, 10. Posterior border; the lower 10 marks the articulating surface for the palate bone. 11,11. Groove of the descending palatine canal. 12. Anterior border of the bone. 13, 13. Palate process. 14. Nasal crest. 15. Nasal spine. 16. Anterior palatine canal. 17. Situa- tion of the incisive foramen. 18, 18. Alveolar process. irregular by the pushing upwards of the hone by the fangs of the molar teeth. In the articulated skull the opening of the antrum is in the middle meatus of the nose, and is close to the roof of the cavity. The posterior or zygomatic surface is bounded externally by the malar process, and internally by a rough and rounded border, the tuberosity, which is pierced by a number of small foramina, giving passage to the posterior dental nerves and branches of the superior dental artery. The superior border is smooth and rounded, forming the lower boundary of the spheno-maxillary fissure, and marked by a notch, the commencement of the infraorbital canal. The inferior boundary is the alveolar process, containing the last two molar teeth. The orbital surface is triangular and thin, and forms the floor of the orbit. It is bounded internally by an irregular edge, which articulates with the palate, ethmoid, and lachrymal bone ; posteriorly, by the smooth border which enters into the formation of the spheno- SUPERIOR MAXILLARY BONES. maxillary fissure ; and, anteriorly, by a convex margin, partly smooth and partly rough, the smooth portion forming part of the lower border of the orbit, the rough portion articulating with the malar bone. The middle of this surface is channelled by a deep groove and canal, the infraorbital, which terminates at the infraorbital foramen ; and near the root of the nasal process is a slight de- pression, marking the origin of the inferior oblique muscle of the eyeball. “ The four processes of the superior maxillary bone are, the nasal, malar, alveolar, and palate. The nasal process ascends by the side of the nose, to which it forms the lateral boundary, and articulates with the frontal and nasal 1 tones. By its external surface it gives attachment to the levator labii superioris alceque nasi, and to the orbicularis palpebrarum muscle. Its internal surface contributes to form the outer wall of the nares, and is marked transversely by a horizontal ridge, superior turbinal crest, which divides it into two portions, one above the ridge irregular and uneven, for giving attachment to and completing the cells of the lateral mass of the ethmoid ; the other below, smooth and concave, corresponding with the middle meatus. The posterior border is thick, and grooved for the nasal duct; while the prominent margin in front of that groove is continuous with the lower border of the orbit; this margin is marked bv a small tubercle {lachrymal tubercle), which serves as a guide to the introduction of the knife in opening into the lachrymal sac. The malar process, large and irregular, is situated at the angle of separation between the facial and zygomatic surface, and presents a triangular surface for articulation with the malar bone. The alveolar process forms the lower margin of the bone ; it is spongy and cellular in texture, and excavated into deep holes for the reception of eight teeth. By its outer surface, as far forwards as the first molar tooth, it gives origin to the buccinator muscle. The ante- rior portion containing the sockets of the incisor teeth, together with a small portion of the palate process, has a separate centre of ossifica- tion, and in the lower animals remains separate throughout life as the intermaxillary or premaxillary bone. In young human skulls, a fissure running backwards from the outer edge of the second incisor nearly to the incisive foramen, indicates the line of junction of the premaxillary bone with the rest of the maxilla ; and in cases of cleft palate (there being an arrest of development) this portion is present as a distinct bone. The palate process is thick and strong, and projects horizontally inwards from the inner surface of the body of the bone. Superiorly, it is concave and smooth, and forms the lloor of the nares ; inferiorly, it is also concave, but uneven, and assists in the formation of the roof of the palate. The latter surface is marked by a deep groove, which lodges the anterior palatine nerve and artery. Its internal edge is raised into a ridge (nasal or palate crest), which, with a corresponding ridge in the opposite bone, forms a groove for the reception of the LACHRYMAL BONES. vomer. The prolongation of this ridge forwards beyond the level of the facial surface of the bone is the nasal spine. Near the anterior extremity of the internal border is seen a deep groove, which, ex- panding interiorly, forms with its fellow of the opposite side the incisive foramen. When the hard palate (completed by the junction of the two bones) is viewed from below, this foramen is seen to con- tain four smaller foramina, two of which are placed in the middle line, one before the other (foramina of Scarpa), the anterior transmitting the left naso-palatine nerve and the posterior the right; the other two (foramina of Stenson), being placed laterally, form the entrance to the anterior palatine canals and give passage to the anterior palatine arteries. These all open above into the inferior meatus of the nose. Development.—By four centres : one for the anterior part of the palate and incisive portion of the alveolar proces many animals the malar bone is permanently divided into two portions, orbital and malar. Ossification commences in the malar bone soon after the vertebrae. Articulations.—With four bones : three of the cranium, frontal, temporal, and sphenoid ; and one of the face, superior maxillary. Attachment of Muscles.—To five: levator labii superioris pro- prius, zygomaticus minor and major, masseter, and temporal. PALATE BONES. PALATE BONES. The palate bones are situated at the posterior part of the nares, where they enter into the formation of the palate, side of the nose, and posterior part of the floor of the orbit. Each bone resembles in general form the letter L, and is divisible into a horizontal plate, a perpendicular plate, and a pterygoid process or tuberosity. The horizontal plate is quadrilateral; and presents two surfaces, Fio. 113.—Posterior view of the right palate bone in its natural position ; it is slightly turned on one side, to obtain a sight of the internal surface of the perpendicular plate (2). 1. Horizontal plate of the bone; its upper or nasal surface. 2. Perpendicular plate ; its internal or nasal surface. 3, 10, n. Pterygoid process or tuberosity. 4. Internal border of the horizontal plate, which, articu- lating with the similar border of the opposite bone, forms the nasal crest for the reception of the vomer. 5. The pointed process, which, with a similar process of the opposite bone, forms the palate spine. 6. Inferior tur- binal crest. 7. Spheno-palatine notch. 8. Orbital portion. 9. Superior turbinal crest. 10. The smooth surface of the tuberosity, which enters into the formation of the ptery- goid fossa. The facets 11 and 3 articulate with the two pterygoid plates, n with the internal, 3 with the external. one superior, wliicli enters into the formation of the floor of the nares, the other inferior, forming the posterior part of the hard palate. The superior surface is concave, and rises towards its inner PALATE BONES. 114 edge, where it unites with its fellow of the opposite side and forms part of a crest (nasal or palate crest), which articulates with the vomer. The inferior surface is uneven, and marked by a slight transverse ridge, to which is attached the tendinous expansion of the tensor palati muscle. Near its external border are two openings, one large and one small, the posterior palatine foramina; they are the terminations of two minute canals, and transmit the descending palatine artery and nerves. The posterior border is concave, and presents at its inner extremity a sharp point, which, with a corre- sponding point in the opposite bone, constitutes the palate spine for the attachment of the azygos uvulae muscle. The perpendicular piate is also quadrilateral ; and presents two surfaces, one internal or nasal, forming part of the wall of the nares ; the other external, bounding the spheno-maxillary fossa and antrum. The internal surface is marked near its middle by a horizontal ridge (inferior turbinal crest), to which is united the inferior turbinated bone ; and about half an inch above this, by another ridge {superior turbinal crest), for the attachment of the middle turbinated bone. Fig. i 14.—Perpendicular plate of the right palate hone, seen on its external or spheno-maxillary surface. 1. The rough surface of this plate, which articulates with the superior maxillary bone and hounds the antrum. 2. Posterior palatine canal; completed by the tuberosity of the superior maxillary bone and pterygoid process of sphenoid. The rough surface to the left of the canal (2) articulates with the internal pterygoid plate. 3. Splieno-palatine notch. 4, 5,6. Orbital portion of the perpendicular plate. 4. Splieno-maxillary surface of this portion. 5. Orbital surface. 6. Maxillary surface, to articulate with the superior maxillary bone. 7. Sphenoidal por- tion of the perpendicular plate. 8. Pterygoid pro- cess or tuberosity of the bone. The concave surface below the inferior ridge is the lateral boundary of the inferior meatus of the nose ; that between the two ridges corresponds with the middle meatus, and the surface above the superior ridge with the superior meatus. The external surface is rough on each side for articulation with neighbouring bones, and smooth in the middle to constitute the inner boundary of the spheno-maxillary fossa. This smooth surface terminates interiorly in a deep groove, which, being completed by the tuberosity of the superior maxillary bone and pterygoid process of the sphenoid, forms the descending palatine canal. Near the upper part of the perpendicular plate is a large oval notch completed by the sphenoid, the splieno-palatine foramen, which transmits the superior nasal and naso-palatine nerves and spheno- palatine artery, and serves to divide the upper extremity of the bone into two portions, an anterior or orbital, and a posterior or sphenoidal portion. The orbital portion is hollow within, and pre- sents five surfaces externally, three articular and two free ; the three articular are, anterior, which looks forward and articulates with the INFERIOR TURBINATED BONES. superior maxillary bone, internal with the ethmoid, and posterior with the sphenoid. The free surfaces are, superior or orbital, which forms the posterior part of the door of the orbit; and external, which looks into the spheno-maxillary fossa. The internal aspect generally shows a hollow cavity which forms part of the posterior ethmoidal cell. The sphenoidal portion, much smaller than the orbital, has three surfaces, two lateral and one superior. The external lateral surface enters into the formation of the spheno-maxillary fossa ; the internal lateral forms part of the lateral boundary of the nares ; the superior surface articulates with the under part of the body of the sphenoid bone, and assists the sphenoidal spongy bones in closing the sphenoidal sinuses. This portion takes part in the formation of the pterygo-palatine canal. The pterygoid process or tuberosity of the palate bone is the thick and rough process which stands backwards from the angle of union of the horizontal with the perpendicular portion of the bone. It is received into the angular fissure, which exists between the two plates of the pterygoid process at their inferior extremity, and pre- sents three surfaces : one concave and smooth, which forms part of the pterygoid fossa, and gives origin to some fibres of the internal pterygoid muscle ; and one at each side to articulate with the ptery- goid plates. The anterior face of this process is rough, and articulates with the superior maxillary bone. Development.—By a single centre, which appears in the angle of union between the horizontal and perpendicular portion, in the seventh or eighth week. Articulations.—With six bones : two of the cranium, sphenoid and ethmoid ; and four of the face, superior maxillary, inferior tur- binated, vomer, and the palate bone of the opposite side. Attachment of Muscles.—To four: tensor palati, azygos uvulae, internal and external pterygoid. INFERIOR TURBINATED BONES. The inferior turbinated or spongy bone, is a thin layer of light and porous bone, attached to the inferior turbinal crest of the inner Fia. 115.—Inferior turbinated bone of the right side. 1, 1. Its internal or convex surface. 2, 2, 3. Canal for a branch of the spheno- palatine artery. The figure 3 also denotes the anterior border of the bone. 4. Posterior border. 5, 5. Inferior border. 6. Anterior angle. 7. Posterior angle. 8. Superior angle. 9. Lachry nial process. 10. Ethmoidal process. 11. A large irregular process, appertaining to the ethmoidal process, and articulating with the ethmoid bone. 12. An opening into the antrum. wall of tlie nares, and projecting inwards towards the septum. It is somewhat triangular in form, one angle being directed upwards and the curved base downwards ; and slightly curled upon itself, so 116 VOMER. as to bear some resemblance to one valve of a bivalve shell; hence its designation, concha inferior. The internal or convex surface looks inwards and upwards, and forms the inferior boundary of the middle meatus of the nose ; it is marked by one or two longitudinal grooves or canals for branches of the nasal nerves and spheno-palatine artery. The external or concave surface looks downwards and outwards, and constitutes the roof of the inferior meatus. The anterior border looks upwards and forwards, is thin and somewhat concave, and articulates with the inferior turbinal crest of the superior maxillary and with the lachrymal bone. The inferior border is convex, rounded, and free, and thicker than the rest of the bone. The anterior angle, attached to the superior maxillary bone, advances forward nearly to the anterior margin of the nares. The posterior angle, sharp and pointed, is prolonged backwards on the internal pterygoid plate. The superior angle gives origin to three thin and laminated processes. The most anterior of these, lachrymal process, derived from the upper part of the anterior border, articulates with the lachrymal bone ; it is grooved on the external aspect and assists in completing the nasal duct. The posterior process, ethmoidal process, derived directly from the superior angle, articulates with the unciform process of the ethmoid bone ; the middle process, maxillary process, proceeding also from the superior border, is reflected downwards, and assists in completing the inner wall of the antrum, articulating with the superior maxillary and palate bones. Recognition.—If the bone be held with its convex lower edge directed downwards, and the end nearest to the groove for the nasal duct looking forwards, the maxillary process will point to the side to which the bone belongs. Development.—By a single centre, which appears at about the fifth month of foetal life. It affords no attachment to muscles. Articulations.—With four bones : ethmoid, superior maxillary, lachrymal, and palate. VOMER. The vomer (vomer, a ploughshare) is a thin, quadrilateral plate of bone, forming the posterior and inferior part of the septum of the nares. The superior border is broad and expanded, to articulate, in the middle, with the under surface of the body of the sphenoid ; it has projecting on each side a horizontal process or ala, by means of which it articulates with the vaginal processes of the sphenoid. The anterior part of this border is hollowed into a sheath for the recep- tion of the rostrum of the sphenoid. The inferior border is thin and uneven, and is received into the grooved summit of the palate crest of the superior maxillary and palate bones. The posterior border is sharp and free, and forms the posterior division of the two nares. The anterior border is more or less deeply grooved for the reception of the central lamella of the ethmoid and the carti- lage of the septum. The lateral surfaces are smooth and marked by small furrows for vessels ; each has a groove which runs downwards and forwards, giving passage to the naso-palatine nerve, and termi- nates interiorly at the upper opening of the canal of Scarpa, The INFERIOR MAXILLARY BONE. 117 Fig. ii6.—The vomer viewed on its left aspect, i, i. Its superior border, with the two ate. 2, 2. Inferior border. 3. Posterior border. 4, 4. That por- tion of the anterior border which articulates with the central lamella of the ethmoid. 3, 5. Inferior portion of the anterior border, which unites with the cartilage of the septum. 6, 6. An elevation on the bone mark- ing its point of separation into two layers ; the two layers are seen along the whole length of the anterior border from 4 to the lower 5. vomer not unfrequently presents a convexity to one or the other side ; generally, it is said, to the left. Development.—By a single centre, which makes its appearance at the same time with those of the vertebrae. Ossification begins from below and proceeds upwards. At birth, the vomer presents the form of a trough, in the concavity of which the cartilage of the septum nasi is placed ; it is this disposition which subsequently enables the bone to embrace the rostrum of the sphenoid. The vomer has no muscles attached to it. Articulations.—With six bones : sphenoid, ethmoid, two superior maxillary, two palate ; and wit h the cartilage of the septum. INFERIOR MAXILLARY BONE. The lower jaw or mandible is the arch of bone which contains the inferior teeth ; it is divisible into a horizontal portion or body, and a perpendicular portion, the ramus, at each side. The body is divisible into two portions. That above the mental foramen (alveolar) is of spongy texture, and contains the sockets for the teeth—that below this foramen (basilar) is thick and rounded ; it is dense in structure, and is marked by ridges for the attachment of muscles. Tlie relative proportion of these two parts varies with the age of the individual : in childhood, in consequence of contain- ing the two sets of teeth, the alveolar portion is large, and the mental foramen is near the lower border of the bone ; in old age, on the contrary, from the loss of teeth and consequent absorption of the alveolar process, the basilar portion alone remains, and the mental foramen is situated near its upper border. In adult age the alveolar and basilar portions are of equal depth, the mental foramen being situated midway between the upper and lower border. Upon the external surface of the body, at the middle line, and INFERIOR MAXILLARY BONE. 118 extending from between the two first incisor teeth to the chin, is a slight ridge, crista mentalis, which indicates the point of conjunction of the lateral halves of the bone in the young subject, the symphysis. The ridge expands below into a triangular eminence, the mental protuberance (or mentum), and this at the lower edge of the bone is marked by a slight depression, the mental dimple. Immediately external to this ridge is a depression which gives origin to the de- pressor labii inferioris muscle ; and, corresponding with the root of the lateral incisor tooth, another depression, the incisive fossa, for the levator labii inferioris. A few fibres of the orbicularis oris (accessory fibres) are attached to the base of the alveolar process, immediately above the incisive fossa. Farther outwards is an oblique opening, the mental foramen, for the exit of the mental nerve and inferior dental artery ; and below this foramen, the commencement of a ridge, the external oblique ridge, which gives attachment to the depressor anguli oris. Near the posterior part of this surface is a rough impression made by the masseter muscle ; and, immediately in front of this impression, a groove for the facial artery. The external surface of the lower border of the bone gives attachment to some fibres of the platysma myoides muscle. The buccinator muscle arises from the base of the alveolar process as far forwards as the first molar tooth. The projecting tuberosity at the posterior extremity of the lower jaw, at the point where the body and ramus meet, is the angle. Upon the internal surface of the body of the bone, at the sym- physis, are two small pointed tubercles (mental tubercles) ; inline- Fig. i 17.—The lower jaw. 1. Body. 2. Ramus. 3. Symphysis. 4. Fossa for the depressor labii iuferioris muscle. 5. Mental foramen. 6. External oblique ridge. 7. Groove for the facial artery ; the situation of the groove is marked by a notch in the bone a little in front of the figure. 8. The angle. 9. Extremity of the mylo-liyoidean ridge. 10. Coronoid process. 11. Condyle. 12. Sigmoid notch. 13. Inferior dental foramen. 14. Mylo-liyoidean groove. 15. Alveolar process, i. Middle and lateral incisor tooth of one side. c. Canine tooth, b. Two bicuspids, m. Three molars. diately beneath these, two other tubercles less marked ; beneath them, a ridge, and beneath the ridge two depressions of some size. These four' points give attachment, from above downwards, to the genio-hyo-glossi, genio-hyoidei, part of the mylo-hyoidei, and digastric muscles. Running outwards into the body of the bone from the above ridge is a prominent line, the mylo-hyoidean ridge, which gives attachment to the mylo-hyoid muscle ; above its pos- terior termination, and near the margin of the alveolar process, the PLATE 6. Levator menti. Mental foramen. Dep. iabii inf Ext. ptery goid. Inferior dental P foramen. Mylo-hyoid groove. - Genio-hyo-glossus. -Genio-hyoideus. INFERIOR MAXILLARY BONE. superior constrictor muscle and pterygo-maxillary ligament have their attachment. Immediately above the ridge, and by the side of the symphysis, is a smooth concave surface, which corresponds with the sublingual gland ; and below the ridge, and more externally, a deeper fossa for the submaxillary gland. The superior border of the body of the bone is the alveolar process, furnished in the adult with alveoli for sixteen teeth. The inferior border or base is rounded and smooth ; thick and everted in front to form the chin, and thinner behind where it merges into the angle of the bone. The ramus is a strong square-shaped process, differing in direction at various periods of life ; thus, in the foetus and infant, it is almost parallel with the body ; in youth it is oblique, and gradually ap- proaches the vertical direction until manhood ; in old age, after the loss of the teeth, it again declines, and assumes the oblique direction. On its external surface it is rough, for the attachment of the masseter muscle ; and at the junction of its posterior border with the body of the bone it has a rough tuberosity, the angle of the lower jaw, which gives attachment by its inner margin to the stylo- maxillary ligament. The upper extremity of the ramus presents two processes, sepa- rated by a concave sweep, the sigmoid notch. The anterior is the coronoid process; it is sharp and pointed, and gives attachment to the temporal muscle. The posterior process is the condyle, which is flattened from before backwards, oblique in direction, and smooth on its upper surface, to articulate with the glenoid cavity of the temporal bone. The constriction around the base of the condyle is its neck, into the external aspect of which is attached the external lateral ligament. A fossa on the anterior part of the neck of the condyle gives attachment to the external pterygoid muscle. The sigmoid notch is crossed by the masseteric artery and nerve. The internal surface of the ramus is marked near its centre by a large oblique foramen, the inferior dental, for the entrance of the inferior dental artery and nerve into the dental canal. Bounding this opening is a sharp margin (lingula mandibularis), to which is attached the long internal lateral ligament, and passing downwards from the opening a narrow groove which lodges the mylo-hyoid vessels and nerve. To the uneven surface above and in front of the inferior dental foramen is attached the temporal muscle, and to the rough internal surface of the angle, the internal pterygoid. Development-—In its earliest condition the inferior maxilla consists of fibrous tissue investing a cartilaginous rod called the Cartilage of Meckel, formed in the first post-oral or mandibular arch. Ossific deposit takes place (probably by several centres which fuse early), mainly in fibrous tissue, but the portion at the symphysis is formed by direct ossification of the Cartilage of Meckel, and the condyle and back part of the ramus, including the angle, are formed from plates of cartilage unconnected with Meckel’s cartilage. The lower jaw is the earliest of the bones of the skeleton to exhibit H9 120 SUTURES. ossification, with the exception of the clavicle. At the time of birth it consists of two lateral halves united by fibrous tissue ; ossific union of the symphysis takes place during the first year. Articulations.—With the glenoid fossae of the two temporal bones, through the medium of a fibro-cartilage. Attachment of Muscles.—To fifteen pairs : by the external sur- face, commencing at the symphysis and proceeding outwards, levator labii inferioris, depressor labii inferioris, depressor anguli oris, platysma myoides, a few fibres of the orbicularis oris, buccinator, and masseter; by the internal surface, also commencing at the symphysis, the genio-hyo-glossus, genio-hyoid, mylo-hyoid, digas- tric, superior constrictor, temporal, external pterygoid, and internal pterygoid. The 1 tones of the cranium and face are connected with each other by means of sutures (sutura, a seam). That is, the edges of the bone are roughened or uneven, are accurately adapted to each other, and united by a small quantity of fibrous tissue. When the process of union of the bones of the skull is retarded by over-distension of the head, as in hydrocephalus, and sometimes without any such apparent cause, distinct ossific centres are developed in the interval between the edges ; and, being surrounded by the suture, form independent pieces which are called ossa triquetra, or ossa Wormiana. These are most frequently found in the lamb- doidal suture; but one sometimes occurs at the junction of the anterior inferior angle of the parietal bone with the tip of the great wing of the sphenoid ; it is called the pterion ossicle. The sutures may be divided into (i) those at the vertex, (2) those at the side of the skull, and (3) those at the base. Those at the vertex are the coronal, sagittal, and lambdoidal. The coronal suture (Fig. 118) extends transversely across the vertex of the skull, and connects the frontal with the parietal bones. In the formation of this suture the edges of the articulating bones are bevelled, so that the parietal rest on the frontal at each side, and in the middle the frontal rests on the parietal bones. The sagittal suture extends longitudinally backwards along the vertex of the skull, from the middle of the coronal to the apex of the lambdoidal suture. It is much serrated, and serves to unite the two parietal bones. In the young subject, and sometimes in the adult, this suture is continued through the middle of the frontal bone to the root of the nose, under the name of frontal suture. Ossa triquetra are sometimes found in the sagittal suture. The lambdoidal suture is named from some resemblance to the Greek letter lambda (A), consisting of two branches, which diverge at an acute angle from the extremity of the sagittal suture. This suture connects the occipital with the parietal bones. The sutures at the side of the skull are the squamo-parietal, the spheno-parietal, and the masto-parietal. SUTURES. REGIONS OF THE SKULL. 121 The squamo-parietal suture (Fig. 118) unites the squamous portion of the temporal bone with the parietal, overlapping the lower border of the latter. The spheno-parietal suture is formed by the union of the tip of the great wing of the sphenoid with the anterior inferior angle of the parietal bone. The masto-parietal suture is the continuation backwards of the squamo-parietal; it unites the upper edge of the mastoid portion of the temporal with the back part of the lower border of the parietal. The sutures at the base of the skull are the basilar, petro-occipital, masto-occipital, petro-sphenoidal, and squamo-sphenoidal. The basilar suture is formed by the union of the basilar portions of the occipital and sphenoid bones ; it is obliterated by the fusion of the bones in early adult life. The masto-occipital and petro-occipital sutures are continuous; the former runs between the posterior edge of mastoid, and the lower part of the lateral edge of the occipital; the latter is placed between the petrous portion of the temporal and the basi- and ex-occipital, and has in it the large opening called jugular foramen. The petro-sphenoidal suture is the short, irregular, union of the anterior edge of the petrous bone and the posterior border of the great wing of the sphenoid, and has in it the middle lacerated foramen. The squamo-sphenoidal suture is the continuation downwards of the squamo-parietal suture. Across the upper part of the face is an irregular suture, the trans- verse, which connects the frontal bone with the nasal, superior maxillary, lachrymal, ethmoid, sphenoid, and malar bones. REGIONS OF THE SKULL. The skull, considered as a whole, is divisible into five regions: a superior region or vertex ; two lateral regions ; an inferior region or base ; and an anterior region, the face. The superior region, or vertex of the skull, is bounded anteriorly by the frontal eminences ; on each side hv the temporal crest and parietal eminence ; and behind by the superior curved line of the occipital bone and occipital protuberance. It is crossed transversely by the coronal suture, and marked from before backwards by the sagittal, which terminates posteriorly in the lambdoidal suture. Near the posterior extremity of the region, and on each side of the sagittal suture, is the parietal foramen. The junction of the sagittal and coronal sutures is called the bregma, and lies vertically above the external auditory meatus ; the junction of the sagittal and lambdoidal sutures is named the lambda, and is usually situated about 2I in. above the external occipital protuberance (60 mm., Clark). The part of the vertex in the neighbourhood of REGIONS OF THE SKULL. 122 the parietal foramen is generally a little flattened ; it has received the name of obelion. On the inner or cerebral surface of this region is a shallow groove extending along the middle line from before backwards, for the superior longitudinal sinus ; at each side of this groove are several small fossae for the Pacchionian bodies, and farther outwards, digital fossae corresponding with the convexities of the convolutions, and numerous ramified grooves for lodging the branches of the meningeal arteries. Each lateral region of the skull is divisible into three portions ; temporal, mastoid, and zygomatic. The temporal portion or temporal fossa is bounded above and behind by the temporal crest, in front by the external angular process of the frontal and by the malar bone, and below bv the zygoma. It Fig. ii8.—Front view of the skull, i. Frontal portion of the frontal bone. The 2 immediately over the root of the nose refers to the glabella; the 3 over the orbit to the supraorbital ridge. 4. Optic foramen. 5. Sphen- oidal fissure. 6. Spheno-maxillary fissure. 7. Toe commencement of the nasal duct. The figures 4, 5, 6, 7, are within tlie orbit. 8. Opening of the anterior nares, divided into two parts by the vomer; the figure is placed upon the latter, g. Infraorbital fora- men. 10. Malar bone. 11. Symphysis of the lower jaw. 12. Mental fora- men. 13. ltamus of the lower jaw. 14. Parietal bone. 15. Coronal suture. 16. Temporal bone. 17. Squamo- parietal suture. 18. Upper part of the great wing of the sphenoid bone. 19. Commencement of the temporal crest. 20. Zygoma. 21. Mastoid pro- cess. is formed by part of the frontal, great wing of the sphenoid, parietal, squamous portion of the temporal, malar bone, and zygoma, and is crossed by six sutures, the transverse of the face, coronal, squamo- parietal, spheno-parietal, spheno-malar, and squamo-sphenoiaal; it lodges the temporal muscle with the deep temporal arteries and nerves. The mastoid portion is rough, for the attachment of muscles. On its posterior part is the mastoid foramen ; and below, the mastoid process. In front of the mastoid process is the external auditory meatus, surrounded by the external auditory process ; and in front of the meatus the glenoid cavity, bounded above by the middle root of the zygoma, and in front by the eminentia articularis. The zygomatic portion, or fossa, is the irregular cavity below the zygoma, bounded in front by the superior maxillary bone, internally REGIONS OF THE SKULL. by the external pterygoid plate, above by the part of the great wing of the sphenoid external to the pterygoid ridge, and lower part of the squamous portion of the temporal bone ; and externally by the zygomatic arch and ramus of the lower jaw. It contains the external pterygoid, part of the temporal, and internal pterygoid muscles ; and the internal maxillary artery and inferior maxillary nerve, with their branches. At the inner side and upper part of the zygomatic fossa are two fissures, spheno-maxillary and pterygo-maxillary. The sp/ieno-maxillary fissure, horizontal in direction, opens into the orbit, and is situated between the great wing of the sphenoid and the superior maxillary bone. It is completed externally by the malar bone. The pterygo-maxillary fissure is vertical, and descends at a right angle from the extremity of the preceding. It is situated between the pterygoid process and the tuberosity of the superior maxillary bone, and transmits the internal maxillary artery. At the angle of junction of these two fissures is a small space, the spheno-maxillary fossa, bounded by the sphenoid, palate, and superior maxillary bones. The base of the skull presents an internal or cerebral, and an external or basilar surface. The cerebral surface is divisible into three parts, which are named anterior, middle, and posterior fossa of the base of the cranium. The anterior fossa is somewhat convex at each side, where it corre- sponds with the roof of the orbits; and concave in the middle, in the situation of the ethmoid bone and interior part of the body of the sphenoid. The latter and the free edges of the lesser wings constitute its posterior boundary. It supports the anterior lobes of the cerebrum. In the middle line of this fossa, at its anterior part, is the crista galli; immediately in front of that process, the foramen caecum, which gives passage to a small vein from the nose to the superior longitudinal sinus ; and on each side, the cribriform plate with its foramina, for the transmission of the filaments of the olfactory nerve, and a slit for the nasal branch of the ophthalmic nerve. On the outer edges of the cribriform plate are seen the openings of the anterior and posterior internal orbital foramina. Farther back in the middle line is the olivary process, and, at the sides of this process, the optic foramina, anterior and middle clinoid processes, and vertical grooves for the internal carotid arteries. The middle fossa of the base, deeper than the preceding, is bounded in front by the lesser wing of the sphenoid ; behind, by the upper border of the petrous portion of the temporal bone ; and is divided into two lateral parts by the sella turcica. It is formed by the posterior part of the body, great wing, and spinous process of the sphenoid, and by the petrous and squamous portion of the temporal bones. In the centre of this fossa is the sella turcica, which lodges the pituitary gland and circular sinus, bounded in front by the anterior and middle, and behind by the dorsum sellce and posterior clinoid processes. On each side of the sella turcica is the carotid groove for the internal carotid artery, cavernous plexus of nerves, 123 REGIONS OF THE SKULL. 124 cavernous sinus, and orbital nerves; and farther outwards the following foramina, from before backwards : sphenoidal fissure (fora- men lacerum anterius) for the transmission of the third, fourth, three branches of the ophthalmic division of the fifth, and the sixth nerve, and ophthalmic vein ; foramen rotundum, for the superior maxillary nerve ; foramen ovale, for the inferior maxillary nerve, lesser meningeal artery, and lesser petrosal nerve ; foramen Vesalii for a small vein ; foramen spinosum, for the middle meningeal artery ; foramen lacerum basis cranii (foramen lacerum medium), which is, in the recent state, closed in by fibrous tissue below, and is crossed by the internal carotid artery, carotid plexus, and petrosal branch of the Vidian nerve. On the anterior surface of the petrous portion of the temporal bone is a groove, leading to a fissured open- Fig. i 19.—Cerebral surface of the base of the skull. 1. One side of the anterior fossa; the figure is placed on the roof of the orbit, formed by the orbital plate of the frontal bone. 2. Lesser wing of the sphenoid. 3. Crista galli. 4. Foramen caecum. 5. Cribriform plate of the ethmoid. 6. Olivary process. 7. Optic fora- men. 8. Anterior clinoid process. 9. Carotid groove for the internal carotid artery and cavernous sinus. 10, 11, 12. Middle fossa. 10 marks the great wing of the sphenoid, n. Squamous portion of the temporal bone. 12. Petrous portion. 13. Sella turcica. 14. Basilar portion of the sphenoid and occipital bone. The uneven ridge between Nos. 13, 14, is the dorsum sella;, and the pro- minent angles of this ridge the posterior clinoid processes. 15. Fora- men rotundum. 16. Foramen ovale. 17. Foramen spinosum; the small irregular opening between 17 and 12 is the hiatus Fallopii. 18. Posterior fossa. 19, ig. Groove for the lateral sinus. 20. Ridge which gives attach- ment to the falx corcbelli. 21. Foramen magnum. 22. Meatus auditorius interims. 23. Jugular foramen. ing, the hiatus Fallopii, for the petrosal branch of the Vidian nerve ; and immediately beneath this a smaller foramen, for the lesser petrosal nerve. Towards the apex of the petrous portion is the notch for the fifth nerve, and below it a slight depression for the Gasserian ganglion. Farther outwards is the eminence which marks the position of the perpendicular semi-circular canal. Proceeding from the foramen spinosum are two grooves, which indicate the course of the trunks of the middle meningeal artery. The whole fossa lodges the temporo-sphenoidal lobes of the cerebrum. The posterior fossa, larger than the other two, is formed by the occipital bone, petrous and mastoid portion of the temporals, and by a small part of the sphenoid and parietals. It is bounded in front by the upper border of the petrous portion and dorsum sellae, and REGIONS OF THE SKULL. 125 along its posterior circumference by the groove for the lateral sinuses ; it gives support to the pons Varolii, medulla oblongata, and cerebellum. In the centre of this fossa is t lie foramen magnum, bounded at each side by a rough tubercle, which gives attachment to the odontoid ligament, and by the anterior condylar foramen. In front of the foramen magnum is the concave surface which supports the medulla oblongata and pons Yarolii, and on each side the following foramina, from before backwards. The internal auditory meatus for the auditory and facial nerves and auditory artery ; behind, and externally to this, is a small foramen leading into the aqucedudus vestibuli; and below it, partly concealed by the edge of the petrous bone, the aqucec/uctus cochleae; next, a long fissure, the foramen lacerum posterius or jugular foramen, partially divided into two by the jugular spine, the outer portion giving passage to the termination of the inferior petrosal and lateral sinuses, and the inner to the ninth, tenth, and eleventh pairs of nerves. Converging towards this foramen from behind is the deep groove of the lateral sinus, and from the front the groove for the inferior petrosal sinus. Behind the foramen magnum is the internal occipital crest, which gives attachment to the falx cerebelli, and divides the two inferior tossee of the occipital bone ; and above the ridge is the internal occipital protuberance, the transverse groove lodging the lateral sinus, and the transverse ridge giving attachment to the tentorium cerebelli. The external surface of the base of the skull is extremely uneven. From before backwards it is formed by the palate processes of the superior maxillary and palate bones ; the vomer ; pterygoid, spinous processes, and part of the body of the sphenoid ; under surface of the squamous, petrous, and mastoid portion of the temporals ; and by the occipital bone. The palate processes of the superior maxil- lary and palate bones constitute the hard palate, which is raised above the level of the rest of the base (when the skull is turned over for the purpose of examination), and is surrounded by the alveolar processes containing the teeth of the upper jaw. At the anterior extremity of the hard palate, and directly behind the front incisor teeth, is the anterior palatine or incisive foramen, which transmits the naso-palatine nerves and anterior palatine arteries. At the posterior angles of the palate are the posterior palatine fora- mina, for the palatine nerves and arteries. Passing inwards from these foramina is the transverse ridge, to which are attached the aponeurotic expansions of the tensor palati muscles ; and at the middle line of the posterior border, the palate spine, which gives origin to the azygos uvula). The hard palate is marked by a crucial suture, which distinguishes the four processes of which it is com- posed. Behind, and above the hard palate, are the posterior nares, separated bv the vomer, and bounded at each side by the internal pterygoid plates. At the base of the pterygoid plates are the pterygo-palatine canals. The internal pterygoid plate is long and narrow, terminated at its apex by the hamular process, and at 126 REGIONS OF THE SKULL. its base by the scaphoid fossa. The external plate is broad ; the space between the two is the pterygoid fossa ; it contains part of the internal pterygoid muscle, and the tensor palati. Externally to the external pterygoid plate is the zygomatic fossa. Behind the nasal fossae, in the middle line, is the under surface of the body of the sphenoid, and the basilar process of the occipital bone, and still farther back, the foramen magnum. At the base of the external pterygoid plate on each side, is the fora wen ovale, and behind this the foramen spinosum with the prominent spine which gives attach- ment to the long internal lateral ligament of the lower jaw and laxator tympani muscle. Running outwards from the apex of the spinous process of the sphenoid bone is the fissure of Glaser, which crosses Fig. 120.—External or basilar surface of the base of the skull, i, i. The hard palate. The figures are placed on the palate processes of the superior maxillary bones. 2. Inci- sive foramen. 3. Palate process of the palate bone. The large opening near the figure is the posterior palatine foramen. 4. Palate spine; the curved line upon which the number rests is the transverse ridge. 5. Vomer, dividing the openings of the posterior nares. 6. Internal pterygoid plate. 7. Scaphoid fossa. 8. External pterygoid plate. The interval between 6 and 8 (right side of the figure) is the pterygoid fossa. 9. Zygomatic fossa. 10. Basilar pro- cess of the occipital bone. 11. Fora- men magnum. 12. Foramen ovale. 13. Foramen spinosum. 14. Glenoid fossa. 15. Meatus auditorius exter- nus. 16. Foramen lacerum medium. 17. The carotid foratneu of the left side. 18. Jugular foramen. 19. Styloid process. 20. Stylo-mastoid foramen. The elevation just to the right of the number is the jugular tubercle ; and the groove to its left the digastric fossa. 21. Mastoid process. 22. One of the condyles of the occipital bone. 23. Posterior condylar fossa. the glenoid fossa transversely, and divides it into an anterior smooth surface, hounded by the eminentia articularis, for the condyle of the lower jaw, and a posterior rough surface for a part of the parotid gland. Behind the foramen ovale and spinosum is the irregular fissure between the spinous process of the sphenoid bone and the petrous portion of the temporal, the foramen lacerum basis cranii (called also foramen lacerum medium), which lodges the internal carotid artery, and in which the carotid branch of the Vidian nerve joins the carotid plexus. Following the direction of this fissure outwards, we see the foramen for the Eustachian tube, and that for the tensor tympani muscle, separated from each other by the pro- cessus cochleariformis. Behind the fissure is the pointed process ORBITS 127 of the petrous bone which gives origin to the levator palati and tensor tympani muscles, and, externally to this process, the carotid foramen for the transmission of the internal carotid artery and ascending branches of the superior cervical ganglion of the sym- pathetic ; and behind the carotid foramen, the jugular foramen and jugular fossa. Externally, and somewhat in front of the latter, is the styloid process, and at its base the vaginal process. Behind and at the foot of the styloid process is the stylo-mastoid foramen, for the facial nerve and stylo-mastoid artery, and farther outwards the mastoid process. At the inner side of the root of the mastoid process is the digastric fossa ; and a little farther inwards, the occi- pital groove. On the sides of the foramen magnum, and near its anterior circumference, are the condyles of the occipital bone. In front of each condyle, and piercing its base, is the anterior condylar foramen for the hypoglossal nerve, and directly behind the condyle the irregular fossa in which the posterior condylar foramen is situated. Behind the foramen magnum are the two curved lines of the occipital bone, the spine, and the protuberance, with the rough surfaces for the attachment of muscles. The Face is somewhat oval in contour, uneven in surface, and excavated for the reception of two principal organs of sense, the eye and the nose. It is formed by part of the frontal bone, and by the bones of the face. Superiorly it is bounded by the frontal eminences ; beneath these are the superciliary ridges, converging towards the glabella ; beneath the superciliary ridges are the supraorbital ridges, terminating externally in the external border of the orbit, and internally in the internal border, and presenting towards their inner third the supraorbital notch, for the supraorbital nerve and artery. Beneath the supraorbital ridges are the cavities of the orbits. Beneath the orbits is the bridge of the nose, overarching the anterior nares ; and on each side of the nares the canine fossa of the superior maxillary bone, the infraorbital foramen, and still farther outwards the prominence of the malar bone ; at the lower margin of the nares is the nasal spine, and beneath it the superior alveolar arch, containing the teeth of the upper jaw. Forming the lower boundary of the face is the lower jaw, containing in its alveolar process the lower teeth, and projecting interiorly to constitute the chin; on each side of the chin is the mental foramen. If a per- pendicular line be drawn from the inner third of the supraorbital ridge to the inner third of the body of the lower jaw, it will be found to intersect three openings : the supraorbital, infraorbital, and mental, each giving passage to a facial branch of the fifth nerve. The orbits are two quadrilateral hollow cones, situated in the upper part of the face, and intended for the reception of the eye- balls, with their muscles, vessels, and nerves, and the lachrymal ORBITS. 128 SPHENO-MAXILLARY FOSSA. glands. The central axis of each orbit is directed outwards, so that the axes of the two, continued into the skull through the optic foramina, would intersect over the middle of the sella turcica. The superior boundary of the orbit is formed by the orbital plate of the frontal bone, and part of the lesser wing of the sphenoid ; the inferior by part of the malar bone, superior maxillary, and orbital plate of the palate bone ; the internal, by the nasal process of the superior maxillary, lachrymal, os planum of the ethmoid, and part of the body of the sphenoid ; the external, by the orbital process of the malar bone and great wing of the sphenoid. These may be expressed more clearly in a tabular form :— Frontal. Sphenoid (lesser wing). Outer wall. Malar. Sphenoid (greater wing). Inner wall. Superior maxilla (nasal process). Lachrymal. Ethmoid (os planum). Sphenoid (body). Orbit. Malar. Superior Maxillary. Palate. There are nine openings communicating with the orbit: the optic, for the admission of the optic nerve and ophthalmic artery; the sphenoidal fissure, for the transmission of the third, fourth, the three branches of the ophthalmic division of the fifth nerve, the sixth nerve, and the ophthalmic vein ; the splieno-maxillary fissure, for the passage of the superior maxillary nerve and infraorbital artery to the opening of entrance of the infraorbital canal; temporo-malar foramina, two or three small openings in the orbital process of the malar bone, for the passage of filaments of the orbital branch of the superior maxillary nerve ; anterior and posterior internal orbital foramina in the suture between the os planum and frontal bone, the former transmitting the nasal nerve and anterior ethmoidal vessels, the latter the posterior ethmoidal vessels ; the opening of the nasal duct; and the supraorbital notch or foramen, for the supraorbital nerve and artery. SPHENO MAXILLARY FOSSA. This is a small space situated between the bones of the head and those of the face ; it corresponds in position to the junction of the spheno-maxillary and pterygo-maxillary fissures. It is triangular in form, and is bounded above by the body of the sphenoid and orbital process of the palate, in front by the superior maxillary, behind by the base of the pterygoid plate and lower part of the anterior surface NASAL FOSS^:. 129 of the great wing of the sphenoid, internally by the vertical plate of the palate ; it is wide above, near the base of the skull, but narrow below, where it is continued into the upper part of the descending palatine canal. The fossa has opening into it three fissures and five foramina : the former are the sphenoidal, spheno-maxillary, and pterygo-maxillary ; the latter are the foramen rotundum, Vidian, descending palatine, pterygo-palatine, and spheno-palatine. The foramen rotundum, Vidian, and pterygo-palatine foramina are on the posterior wall, being placed in the order of their enumeration from above downwards ; the spheno-palatine is on the inner wall, and the descending palatine below. The fossa lodges Meckel’s ganglion, the superior maxillary nerve, and the third part of the internal maxillary artery ; and the foramina which open into it (with the exception of the foramen rotundum) give passage to nerve- twigs derived from the ganglion and small branches of the artery. The nasal fossa? are two irregular cavities, situated in the middle of the face, and extending from lief ore backwards. They are bounded above by the nasal spine of the frontal, nasal, ethmoid, sphenoid, and sphenoidal turbinated hones; beloto by the palate processes of the superior maxillary and palate hones ; externally by the superior maxillary, lachrymal, inferior turbinated, superior and middle tur- binated bones of the ethmoid, palate, and internal pterygoid plate of the sphenoid ; and the two fossae are separated by the vomer and perpendicular lamella of the ethmoid. The inner wall presents a large triangular notch anteriorly, which in the recent state is tilled in by the cartilage of the septum. These may be more clearly ex- pressed in a tabular form :— NASAL FOSS.E. Frontal (nasal spine). Nasal bones. J Ethmoid. Sphenoid. Sphenoidal turbinated bones. Superior maxillary. Lachrymal. Inferior turbinated. Ethmoid. Palate. Internal pterygoid plate. Vomer and ethmoidal plate. Superior maxillary. Lachi-ymal. Inferior turbinated. Ethmoid. Palate. Internal pterygoid plate. Nasal fossa. Nasal fossa. Palate processes of superior maxillary bones. Palate processes of palate bones. NASAL FOSSiE. Each nasal fossa is divided into three irregular longitudinal pas- sages, or meatuses, by three processes of bone, which project from its outer wall—the superior, middle, and inferior turbinated bone ; the superior and middle turbinated bone being processes of the ethmoid ; the inferior, a distinct bone of the face. The superior meatus oc- cupies the superior and posterior part of each fossa ; it is situated between the superior and middle turbinated bone, and has opening into it two foramina—viz., foramen of the posterior ethmoidal cells, and spheno-palatine foramen. The sphenoidal sinuses usually open into the upper part of the nasal fossae, immediately behind the superior turbinated bone. The middle meatus is the space between Fiq. 121.—Longitudinal section of the nasal fossae made immediately to the right of the middle line, the bony septum removed in order to show the external wall of the left fossa, i. Frontal bone. 2. Nasal bone. 3. Crista galli. The groove between 1 and 3 is the lateral boundary of the foramen caecum. 4. Cribriform plate of tlie ethmoid. 5. Sphenoidal cells. Bones 2, 4, and 5 form the supe- rior boundary of the nasal fossa. 6. Basilar portion of the sphenoid bone. 7, 7. Palate process of supe- rior maxillary bone. The groove between 7, 7, is the lateral half of the incisive canal, and the dark aperture in the groove the inferior termination of the left naso-pala- tine canal. 8. Nasal spine. 9. Palate process of palate bone. a. Superior turbinated bone. 6. Su- perior meatus, c. A probe passed into the posterior ethmoidal cells, d. Opening of the sphenoidal cells into the superior meatus, e. Splieno-palatino foramen. /. Middle turbinated bone, g, g. Middle meatus. 7<. A probe passed into the in- fundibulum leading from the frontal sinuses and anterior ethmoidal cells; the triangular aperture immediately above the letter is the opening of the antrum. i. Inferior turbinated bone, k, k. Inferior meatus. I, l. A probe passed up the nasal duct, showing the direction of that canal, in. Internal pterygoid plate. n. Its liamular process. 0. External pterygoid plate, p. Root of pterygoid processes. q. Posterior palatine foramina, r. Roof of the left orbit. *. Optic foramen. t. Groove for the last turn of the internal carotid artery converted into a carotico- clinoid foramen, v. Sella turcica, s. Posterior clinoid process. the middle and inferior turbinated bone ; it also presents two fora- mina, the opening of the infundibulum {the common opening of the anterior ethmoidal cells and frontal sinus), and of the antrum. The largest of the three passages is the inferior meatus, which is the space between the inferior turbinated bone and the floor of the nasal fossa ; in it there are two foramina, the termination of the nasal duct, and the opening of the anterior palatine canal. In the recent state the Eustachian tube looks forward into the nares, and opens into the pharynx just behind the inferior meatus. The nasal fossae commence upon the face by a large irregular opening, the anterior nares, and terminate posteriorly in the two posterior nares. OS HYOIDES. 131 OS HYOIDES. The os hyoides (lingual bone) gives support to the tongue, and attachment to numerous muscles in the neck. It is named from its resemblance to the Greek letter v, and consists of a central portion or body, of two larger cornua, which project backwards from the body ; and two lesser cornua, which ascend from the angle of union between the body and the greater cornua. The body (basi-hrjal) is somewhat quadrilateral, rough and convex on its antero-superior surface, by which it gives attachment to muscles; con- cave and smooth on the postero-in- ferior surface, by which it lies in con- tact with the tliyro-liyoid membrane. The greater cornua (thyro-hyals) are flattened from above downwards, and terminated posteriorly by a tubercle ; and the lesser cornua (cerato-hycils), conical in form, give attachment to the stylo-hvoid ligaments. In early age and in the adult the cornua are connected with the body by distinct diarthrodial joints ; in old age they become united by bone. Development.—By five centres, one for the body, and one for each cornu. Ossification commences in the greater cornua and body during the last month of foetal life, and in the lesser cornua soon after birth. The cornua do not unite with the body till after middle life. Attachment of Muscles.—To eleven pairs : sterno-hyoid, thyro- hyoid, omo-hyoid, pulley of the digastricus, stylo-hyoid, mylo-hyoid, genio-hyoid, genio-liyo-glossus, hyo-glossus, lingualis, and middle constrictor of the pharynx. It also gives attachment to the stylo- hyoid, thyro-hyoid, and hyo-epiglottic ligaments, and to the thyro- hvoid membrane. Fig. i22. — The os hyoides seen from before, x. Antero-superior, or convex side of the body. 2. Great cornu of the left side. 3. Lesser cornu of the same side. THE THORAX. The skeleton of the thorax consists of the dorsal vertebrae, already described, the sternum, ribs, and costal cartilages. The sternum (Fig. 123) is situated in the middle line of the front of the chest, and is oblique in direction, the superior end lying within a few inches of the vertebral column, the inferior being pro- jected forwards so as to he placed at a considerable distance from the spine. The bone is Hat in front, and marked by five transverse lines STERNUM. STERNUM. which indicate its original subdivision into six pieces. It is slightly concave behind, broad and thick above, narrowest at the junction of the first and second pieces, and flattened and pointed below ; it is divisible in the adult into three pieces, superior, middle, and inferior, or presternuin, mesosternum, and metasternum. The manubrium (yresternum) is somewhat triangular in shape ; it is broad and thick above, where it presents a concave border, suprasternal or interclavi- cular notch ; and narrow at its junction with the m ddle piece. At each superior angle is a deep articular depression for the clavicle ; and on either side two notches for articulation with the cartilage of the first rib, and one-lialf that of the second. The junction of the manubrium and body is marked by a transverse ridge, the sternal angle, which serves as a guide to the anterior extremity of the second rib. The body or gladiolus (mesostern um), consideralfly longer than the superior, is broad in the middle, and somewhat narrower at each extremity. It presents at each side six articular notches for the lower half of the second rib, the four next ribs, and the upper half of the seventh. The articular notches are placed opposite to the lines which indicate the original sub- division of the bone. This Piece is sometimes perforated bv an opening of variable size, resulting from arrest of development. The ensiform or xiphoid process (metasternum) is the smallest of the three, often merely cartilaginous, and very variable in appear- ance, being sometimes pointed, at other times broad and thin, and at other times, again, perforated by a round hole, or bifid. It pre- sents a notch at each side for articulation with the lower half of the cartilage of the seventh rib. Development. — The sternum is usually developed from six centres, one for each of the segments of which the bone primarily Fig. 123.—Anterior view of the thorax. 1. Manubrium. 2. Body or gladiolus. 3. Ensi- form cartilage. 4. First dorsal vertebra. 5. Last dorsal vertebra. 6. First rib. 7. Its head. 8. Its neck, resting against the trans- verse process of the first dorsal vertebra. 9. Its tubercle. 10. Seventh or last true rib. n. Costal cartilages of the true ribs. 12. The last two false ribs or floating ribs. 13. The groove along the lower border of the rib. consists. Ossification commences in the manubrium towards the •end of the sixth month of foetal life, in the second segment about the seventh or eighth month, in the third and fourth about the time of birth, and in the fifth segment during the first year. The osseous centre for the ensiform cartilage is very variable in its advent, being first apparent at any period from the sixth to the fifteenth year, or even later. Frequently, additional nuclei appear in several of the segments, this being more especially the case with the manubrium, in which as many as six centres have occasionally been observed : in the third, fourth, and fifth segments there are frequently two centres which are placed laterally, and it is the irregular union of these pairs that gives rise to the foramina occasionally seen in the sternum towards its lower part. Union of the pieces of the sternum commences from below and proceeds upwards ; the fifth piece unites with the fourth at about puberty, the fourth and third between twenty and twenty-five, the third and second between twenty-five and thirty. The ensiform appendix becomes joined to the body of the sternum at forty or fifty years ; and the manubrium to the body only in very old age. Two small pisiform pieces have been described by Beclard and Breschet, as being situated upon and somewhat be- hind each extremity of the supra-sternal notch of the upper border of the manubrium. Articulations.—With the clavicles and seven costal cartilages on each side. Attachment of Muscles.—To nine pairs and one single muscle —viz., by its anterior surface to the pectoralis major, by its upper border to the sterno-mastoid, by the upper and posterior part of the manubrium to the sterno-hyoid and sterno-thyroid, by the posterior surface of the body to the triangularis sterni, and by the ensiform cartilage to the external oblique, internal oblique, transversalis, rectus, and diaphragm. RIBS. 133 RIBS. The ribs are twelve in number at each side ; the first seven are connected with the sternum by the costal cartilage, and are thence named sternal or true ribs ; the remaining five are the asternal or false ribs ; and the last two, shorter than the rest, and free at their extremities, are the floating ribs. The ribs increase in length from the first to the eighth, whence they diminish to the twelfth ; in breadth they diminish gradually from the first to the last, and, with the exception of the last two, are broader at the anterior than at the posterior end. The first rib is horizontal in direction ; all the rest are oblique, the anterior extremity falling considerably below the posterior. Each rib presents an external and internal surface, a superior and inferior border, and two extremities ; it is curved to correspond with the arch of the thorax, and twisted, so that, when laid on a horizontal surface, one end is tilted up.. The external surface is convex, and marked by the attachment KIES. 134 of muscles; tlie internal is flat, and corresponds witli the pleura ; the superior border is rounded. The inferior border is sharp and grooved on its inner edge, the lower edge of the groove giving attachment to the external, and the upper edge to the internal intercostal muscle. Near its vertebral extremity, the rib is some- what bent; and opposite the bend, on the external surface, is a rough oblique ridge, which gives attachment to a tendon of the sacro- lumbalis muscle, and is called the angle. The distance between the vertebral extremity and the angle increases gradually from the second to the eleventh rib. Beyond the angle is a rough elevation, the tubercle, to which the posterior costo-transverse ligament is at- tached ; and immediately at the base and under side of the tubercle a smooth surface for articulation with the extremity of the transverse process of the corresponding vertebra. The vertebral end of the rib is somewhat expanded, and termed the head, and that portion be- tween the head and tubercle, the neck. On the extremity of the head is an oval smooth surface divided by a transverse ridge into two facets for articulation with two contiguous vertebrm ; the ridge being joined to the intervertebral substance by means of an inter- Fio. 124.—Vertebral extrem- ity of theseventh riboftbc right side. 1. The angle. 2. The tubercle; rough surface for the posterior costo-transverse ligament. 3. Articular surface. 4. Neck of rib. 5. Head, presenting two articular facets. 6. Rough surface for the attachment of the middle costo-transverse ligament. 7. Crest for the anterior costo-transverse ligament. 8. Upper rounded border. 9. Lower sharp border. 10. Groove on the inner edge of the lower border. articular ligament. The posterior surface of the neck is rough, for the attachment of the middle costo-transverse ligament; and upon its upper border is a crest, which gives attachment to the anterior costo-transverse ligament. The sternal extremity is flattened, and presents an oval depression for the reception of the costal cartilage. The ribs that demand especial consideration are the first, tenth, eleventh, and twelfth. The first is the shortest rib ; it is broad and flat, and placed horizontally at the upper part of the thorax, the surfaces looking upwards and downwards, in place of forwards and backwards as in the other ribs. At about the anterior third of the upper surface of the bone, and near its internal border, is a tubercle {scalene tubercle), which gives attachment to the scalenus anticus muscle, and imme- diately before and behind that tubercle, a shallow oblique groove, the former for the subclavian vein, the latter for the subclavian artery. Near the posterior extremity of the bone is a thick and prominent tubercle, with a smooth articular surface for the transverse process of the first, dorsal vertebra ; and between the tubercle and the groove for the subclavian artery is a depression for the attach- KIES AND COSTAL CAKTILAGES. 135 ment of the scalenus medius muscle. There is no angle, and no groove on the under side. Beyond the tubercle is a narrow con- stricted neck ; and at the extremity, a head, presenting a single ar- ticular surface. The second rib, in some of its characters, resembles the first, being flattened from above downwards, and only slightly twisted ; it presents near the middle a rough surface for the attachment of the second and third digitations of the ser- ratus magnus. The tenth rib has a single articular surface on its head. The eleventh and twelfth have each a single articular surface on the head, no neck or tubercle, and are pointed at the free extremity. The eleventh lias a slight ridge, representing the angle, and a shallow groove on the lower border ; the twelfth has neither. Development.—The ribs are developed by three centres ; one for the central part, one for the head, and one for the tubercle. The last two have no centre for the tubercle. Ossification commences in the body somewhat before its appearance in the vertebra}; the epi- physeal centres for the head and tubercle appear between sixteen and twenty, and are consolidated with the rest of the bone at twenty- five. Articulations.—Each rib articulates with two vertebra; and one costal cartilage, with the exception of the first, tenth, eleventh, and twelfth, which articulate each with a single vertebra only. Attachment of Muscles.—Intercostal muscles, scalenus anticus, medius, and posticus, pectoralis minor, serratus magnus, obliquus externus, latissimus dorsi, quadratus lumborum, serratus posticus superior, serratus posticus inferior, sacro-lumbalis, longissimus dorsi cervicalis ascendens, levatores costarum, transversalis, and dia- phragm. COSTAL CARTILAGES.—The costal cartilages serve to prolong the ribs forward to the anterior part of the chest, and contribute mainly to the elasticity of the thorax. They are broad at their attachment with the ribs, and taper slightly towards the sternal end ; they diminish gradually in breadth from the first to the last ; in length they increase from the first to the seventh, and then decrease to the last. The cartilages of the first two ribs are horizontal in direc- tion ; the rest incline more and more upwards. In advanced age Fig. 125.—First rib of left side. 1. Scalene tubercle. 2. Groove for subclavian vein. 3. Groove for sub- clavian artery. 4. Head. 5. Neck. 6. Articular portion of tubercle. 7. Rough portion of tubercle. 8. Anterior end. 136 THE THORAX. the costal cartilages are converted more or less completely into bone, the change taking place earlier in the male than in the female. The first seven cartilages articulate with the sternum ; the three next, with the lower border of the cartilage immediately preceding ; the last two lie free between the abdominal muscles. All the car- tilages of the false ribs terminate by pointed extremities. Attachment of Muscles.—Subclaviue, sterno-thyroid, pectoralis major, internal oblique, rectus, transversalis, diaphragm, triangu- laris sterni, internal intercostals. THE THORAX AS A WHOLE. The thorax is conical in shape, iiattened antero-posteriorly, and wider from side to side than from before backwards. It is formed posteriorly by the dorsal vertebrae, and ribs, the bodies of the former projecting into the cavity, and the latter forming a backward con- vexity on each side, the furrow between the back of the ribs and the spinous processes of the vertebrae being occupied in the recent state by the dorsal muscles. The anterior wall, formed by the sternum and costal cartilages, inclines forwards as it descends, and at its lower end is a depression corresponding to the xiphoid cartilage. The upper edge of the sternum corresponds to the level of the lower part of the body of the second dorsal vertebra in the male, and in the female to the lower part of the body of the third. The female thorax is relatively shorter and rounder than the male, and is also relatively wider in its upper part. The lower part of the thoracic wall encloses the upper part of the abdominal cavity. THE UPPER EXTREMITY. The upper extremity is formed by the clavicle, scapula, humerus, radius, ulna, carpus, metacarpus and phalanges. The clavicle and scapula form the shoulder-girdle. The clavicle (clavis, a hey), or collar-hone, is a long bone, shaped like the italic letter /, and extended across the upper part of the side of the chest from the upper piece of the sternum to the point of the shoulder, where it articulates with the scapula. The curves are so disposed that at the sternal end the convexity, and at the scapular the concavity, is directed forwards. The sternal half of the bone is rounded, and terminates in a broad facet for articulation with the sternum ; this facet is continued for a short distance on to the under surface, where it articulates with the cartilage of the first rib. The CLAVICLE. PLATE 7. CLAVICLE AND SCAPULA. 137 scapular half is flattened from above downwards, and broad at its extremity, the articular surface for the acromion occupying only part of its extent. The upper surface is smooth, convex, and partly subcutaneous ; the under surface rough at its outer part, and ex- cavated into a smooth groove in the middle, where it lodges the subclavius muscle. At the sternal extremity of the under surface is a very rough prominence, which gives attachment to the rhomboid ligament; and at the other extremity a rough tubercle near the posterior border, for the conoid ligament, and a ridge, running Fig. 126.—Clavicle of the right side ; its upper and anterior face. 1. The sternal end. 2. The portion which articulates'with the first rib. 3, 3. Ridge of attachment of the pectoralis major. 4. Acromial end. 5. Surface of articulation with the acromion. 6, 6. Ridge for the attachment of the deltoid. 7, 7. Line of insertion of the trapezius. 8. Line of origin of the sterno-mastoid. forwards and outwards from this, for the trapezoid ligament, both parts of the coraco-clavicular ligament. The opening for the nutrient vessels is seen at the tinder surface of the bone. Development.—By tivo centres ; one for the shaft and one for the sternal extremity ; the former appearing (in membrane) before any other bone of the skeleton, the latter between eighteen and twenty. The epiphysis joins the shaft about the twenty-fifth year. Articulations.—With the sternum, scapula, and cartilage of the first rib. Attachment of Muscles.—'To seven ; sterno-cleido-mastoid, trape- zius, pectoralis major, deltoid, subclavius, sterno-liyoid and platysma myoides. SCAPULA. The scapula (aKcnvavr7, a spade) is a flat triangular bone, situated on the posterior aspect and side of the thorax, and occupying the space from the second to the seventh rib. It is divisible into an anterior and posterior surface; superior, inferior, and posterior border ; anterior, superior, and inferior angle ; and processes. The anterior surface, or venter, is concave and uneven, forming the subscapular fossa, and is marked by several oblique ridges which have a direction upwards and outwards. It is occupied by the subscapularis muscle, with the exception of the posterior border, a triangular surface near the superior angle, and similar area near the inferior angle, these parts giving attachment to the serratus magnus. The posterior surface, or dorsum, is convex, and unequally divided into two portions by the spine : that portion above the spine is the supra-spinous fossa ; and that below, the infra-spinous fossa. 138 SCAPULA. The superior border is the shortest of the three ; it is thin and concave, terminated at one extremity by the superior angle, and at the other by the coracoid process. At the base of the coracoid process is the supra-scapular or coraco-scapular notch (converted into a foramen by a ligament), for the transmission of the supra- scapular nerve. The inferior or axillary border is thick, and marked by several grooves and depressions ; it terminates superiorly at the glenoid cavity/and inferiorly at the inferior angle. Immediately below the glenoid cavity is a rough ridge, which gives origin to the long head of the triceps muscle. In the middle of this border is a depression ir..'is7-—Anterior surface or venter of the scapula, i, i, i. Oblique ridges crossing the subscapular fossa. 2, 2. Upper part of the surface occupied by the serratus naagnus muscle. 3. Superior border. 4. Superior angle. 5. Supra-scapular notch. 6. Coracoid process. 7. Acromion pro- cess. 8. Spine of the scapula; the figure 5, while indicating the supra-scapular notch, is placed on the spine. 9. Articular surface of the acromio-clavic.ular joint. 10. Glenoid cavity. 11. Head of the scapula. 12. Its neck. 13, 13. Axillary border; the upper 13 is placed against the ridge for the triceps. 14. Inferior angle. 15. 15. Posterior border. 16. Pro- minence corresponding with the origin of the spine of the scapula. for the teres minor, and beneath this a deeper groove for the teres major ; near the inferior angle is a projecting lip, which increases the surface of origin of the latter muscle. The posterior border or base, the longest of the three, is turned towards the vertebral column. It is intermediate in thickness between the superior and inferior, and convex. Attached to it are three muscles, the levator anguli scapula) extending from the upper edge of the triangular area at the root of the spine to the superior angle, the rhomboideus minor corresponding in its attachment to the triangular area, and the rhomboideus major attached to the rest of the border. The anterior angle is the thickest part of the bone, and forms the head of the scapula-; it is immediately surrounded by a con- stricted portion, the neck. The head presents a shallow pyriform articular surface, the glenoid cavity, having the pointed extremity upwards ; and at its apex is a rough depression, which gives'attach- PLATE 8. SCAPULA. ment to the long tendon of the biceps. At the anterior and upper part of the glenoid cavity a rudimentary notch is observed in its margin ; this is interesting as corresponding to the notch at the inner side of the acetabulum. The superior angle is thin and pointed. The inferior angle is thick, and smooth upon the posterior surface for the origin of the teres major, and for a large bursa over which the upper border of the latissimus dorsi muscle plays ; it also occa- sionally gives origin to a few fibres of the latter muscle. The spine of the scapula, triangular in form, crosses the upper part of the dorsum of the bone; it commences at the posterior border by a smooth triangular surface over which the fan-shaped tendon of the trapezius glides, and terminates at the point of the shoulder in the acromion process. At a short distance from its origin, where the tri- angular surface rises to the level of the spine, is a prominent tubercle, which marks the ter- mination of the line of attach- ment of the tendon of the trapezius. The anterior border of the spine is smooth and concave, it arises near the neck of the scapida, and is continued into the under surface of the acromion; it encloses a notch, the great scapular notch, between it and the glenoid cavity. The free border of the spine is rough and subcutaneous, and gives at- tachment, by two projecting lips, to the trapezius above and deltoid below ; the surfaces of the spine enter into the formation of the supra- and infra - spinous fossa. The nutrient foramina of the scapula are situated in the base of the spine. The acromion, somewhat tri- angular in form, is flattened from above downwards; it over- hangs the glenoid cavity, the upper surface being rough and subcutaneous, the lower smooth. Near its extremity, on the anterior border, is an oval articular surface, for the end of the clavicle. The coracoid process is a thick, round, and curved process of bone, arising from the upper part of the neck of the scapula, and Fio. 128.—Posterior view of the scapula. 1. Supra - spinous fossa. 2. Infra- spinous fossa. 3. Superior border. 4. Supra-scapular notch. 5. Axillary border. 6. Head of the scapula and glenoid cavity. 7. Inferior angle. 8. Neck of the scapula; the ridge opposite the figure gives origin to the long head of the triceps, g. Pos- terior border or base of the scapula. 10. The spine, n. Triangular smooth surface, over which the tendon of the trapezius glides. 12. Acromion process. 13. One of the nutrient for- amina. 14. Coracoid process. 140 HUMERUS. overarching the glenoid cavity. It is about two inches in length, very strong, and gives attachment by its tip to the biceps and coraco-brachialis muscles, by its anterior border to the pectoralis minor, and by its posterior border to the coraco-acromial liga- ment. Near its base is a rough impression for the conoid ligament, and running forwards from this an oblique ridge for the trapezoid ligament. Development.—By seven centres ; one for the body (including the spine), two for the coracoid process, two for the acromion, one for the inferior angle, and one for the posterior border. The ossific centre for the body appears near the head about the seventh or eighth week, one for the coracoid process during the first year, and a second at the base of the same process in the tenth year ; the acromion process at puberty ; the inferior angle in the fifteenth year ; and the posterior border at seventeen or eighteen. Union between the coracoid process and body takes place during the fifteenth year ; the bone is not complete till after the twenty-second year. Articulations.—With the clavicle and humerus. Attachment of Muscles.—To sixteen; by its anterior surface to the subscapularis and serratus magnus ; posterior surface, supra- spinatus and infra-spinatus ; superior border, omo-hyoid ; posterior border, levator anguli scapulae, rlioinboideus minor, rhomboideus major ; axillary border, long head of the triceps, teres minor, teres major ; upper angle of the glenoid cavity, long tendon of the biceps : spine and acromion, trapezius and deltoid ; coracoid process, pectoralis minor, short head of the biceps, and coraco-bracliialis. The liga- ments attached to the coracoid process are, coraco-acromial, coraco- clavicular, coraco-liumeral, and the costo-coracoid membrane. HUMERUS. The humerus is divisible into a shaft and two extremities. The upper extremity presents a rounded had; a constriction immediately around the base of the head, the anatomical neck; a greater and a lesser tuberosity. The greater tuberosity is situated most externally, and is marked by three facets for the insertion of the supra-spinatus, infra-spinatus, and teres minor muscles. The lesser tuberosity, placed internally, gives attachment to the tendon of the subscapularis. The tuberosities are separated by a vertical furrow, the bicipital groove, which lodges the long tendon of the biceps, and a branch of the anterior circumflex artery. The edges of this groove below the head of the bone are prominent and rough, and called the external and internal bicipital ridges; the former serves for the insertion of the pectoral is major muscle, the later for the tendon of the teres major ; at the bottom of the groove the tendon of the latissimus dorsi is inserted. The constriction of the bone below the tuberosities is the surgical neck, and is so named, in contradistinction to the anatomical neck, from being the seat of the accident called by surgical writers fracture, of the neck of the humerus. The shaft of the bone is somewhat cylindrical at its upper part, and flattened from before backwards below. On the outer side, at about its middle, is a rough triangular eminence (deltoid tuberosity), HUMERUS. 141 Fir. 129. Fig. 130. Fig. 129. —Humerus of the right arm ; its anterior surface. 1. Shaft of the bone. 2. Head. 3. Anatomical neck. 4. Greater tuberosity. 5. Lesser tubero- sity. 6. Bicipital groove. 7. External bicipital ridge. 8. Internal bicipital ridge. 9. Rough surface into which the deltoid is inserted. 10. Nutrient foramen, n. Eminentia capitata. 12. Trochlea. 13. External epicondyle. 14. Internal epicondyle. 15. External supracondylar ridge. 16. Internal supracondylar ridge. 17. Fossa for the coronoid.process of the ulna. Fig. 130.—Humerus of the right arm; its posterior aspect. 1. Shaft. 2. Head. 3, 3. Anatomical neck. 4, 4. Surgical neck. 5. Great tuberosity. 6. Facets of insertion of the infra-spinatus and teres minor. 7. Groove for the musculo-spiral nerve. 8. Back of trochlear surface. 9. Internal epioon- dyle. 10. External epicondyle. n. External supracondylar ridge. 12. Fossa for the reception of the ole- cranon. which gives insertion to the deltoid ; and immediately on each side of this eminence is a smooth depression, corresponding with the origin of the brachialis anticus. On the inner side of the middle of the shaft is a smooth surface for the attachment of the coraco- hrachialis muscle; and behind, an oblique and shallow groove (musculo-spiral c/roove), which lodges the musculo-spiral nerve and superior profunda artery. The foramen for the medullary vessels is situated on the inner surface of the shaft of the bone a little below the coraco-brachial impression ; it is directed downwards. The lower extremity is flattened behind and convex in front; it is terminated interiorly by a long articular surface, divided into two parts by an elevated ridge. The external portion of the articular 142 HUMERUS. surface is a rounded protuberance, capitellum or eminentia capitata, which articulates with the cup-shaped depression on the head of the radius ; the internal portion is a concave and pulley-like surface, trochlea, for articulation with the ulna. It will be noticed that the capitellmn is limited to the anterior and lower aspect of the bone, and is not seen from behind, while the trochlear surface is even more marked behind than in front; the latter is bounded on its inner side by a salient ridge. Projecting beyond the articular surface at each side are the external and internal epicondyle, the latter being consider- ably the longer ; and running up we* is from the epicondyles along the borders of the bone are the suj 'ondylar ridges, of which the external is the most prominent. Immediately in front of the troch- lea is a small depression for receiving the coronoid process of the ulna during flexion of the fore-arm (coronoid fossa); and immedi- ately behind it a large and deep fossa, for containing the olecranon process during extension (olecranon fossa) ; above the trochlea is a small pit (radial fossa), which receives the anterior part of the head of the radius in complete flexion. The average length of the humerus is, in the male thirteen inches, and in the female twelve inches. Development.—By seven centres ; one for the shaft, one for the head, one for the tuberosities, one for the eminentia capitata, one for the trochlea, and one for each epicondyle, the internal preceding the external. Ossification commences in the shaft of the humerus in the eighth week ; in the head during the first year, and in the tubero- sities during the third year ; in the eminentia capitata and trochlea during the third and eleventh year ; and in the epicondyles during the fifth and fifteenth. At the time of birth the shaft is ossified, but the extremities are cartilaginous ; the centre for the head and that for the tuberosities unite during the fifth year. The entire bone is consolidated at twenty. Articulations.—With the glenoid cavity of the scapula, the ulna, and radius. Attachment of Muscles.—To twenty four: by the greater tubero- sity, supra-spinatus, infra-spinatus, and teres minor ; lesser tubero- sity, subscapularis ; external bicipital ridge, pectoralis major ; internal bicipital ridge and groove, teres major and latissimus dorsi ; shaft, external and internal head of the triceps, deltoid, coraco-brachialis, and bracliialis anticus ; external supracondylar ridge and epicondyle extensors and supinators of the fore-arm, viz., supinator longus, extensor carpi radialis longior, extensor carpi radialis brevior, extensor communis digitorum, extensor minimi digit!, extensor carpi ulnaris, anconeus, and supinator brevis ; internal epicondyle flexors and one pronator, viz., pronator radii teres, flexor carpi radialis, palmaris longus, flexor sublimis digitorum, and flexor carpi ulnaris. PLATE 9. Supraspinatus Ext. carp. rad. Iirev. Ext. dig. comm. ,, min. dig. ,, carp. uln. Supin. brevis. Flex, carpi ulnaris. Flex, carpi rad. Palm, long Flex subl. dig. .. carpi uln. ULNA. 143 ULNA. The ulna is divisible into a shaft and two extremities. The upper extremity is large, and forms principally the articulation of the elbow ; the lower extremity is small, and is excluded from the wrist-joint by an interarticular tibrocartilage. The upper extremity presents a semilunar concavity of large size, the greater sigmoid notch, for articulation with the humerus ; and on the outer side a lesser sigmoid notch, for the head of the radius. Bounding the greater sigmoid notch posteriorly is the olecranon pro- cess, and overhanging it in front, a pointed eminence with a rough triangular base, the coronoid process. The olecranon process (&>\evg, elbow ; updvov, head) terminates in front by a sharp beak, which in full extension passes into the olecranon fossa on the humerus ; behind this is a rough and prominent surface or tuberosity for the attach- ment of the triceps muscle ; and on the posterior aspect of the process a smooth triangu- lar area which is subcutaneous. The coronoid process has also a sharp beak in front, and below this a triangular, rough surface (.tuberosity of the ulna) for the brachialis anticus, immediately to the inner side of which one head of the pronator radii teres is attached. Below the lesser sigmoid notch is a rough pit, which gives attachment to some fibres of the supinator brevis. The shaft is prismoid in form, and presents three surfaces, anterior, posterior, and internal ; and three borders. The anterior surface is occupied by the flexor profundus digitorum for the upper three-fourths of its extent; and below, by a depression for the pro- nator quadratus muscle. A little above its middle is the nutrient foramen, directed upwards. On the posterior surface, at the upper part of the bone, is the triangular uneven depression for the anconeus muscle, bounded interiorly by an oblique ridge which runs downwards from the posterior extremity of the lesser sigmoid notch. Below the ridge, the surface is marked into several grooves for the attachment of the extensor ossis metacarpi pollieis, extensor secundi internodii pollieis, and extensor indicis muscles. The Fig. 131.—The two bones of the fore-arm seen from the front. 1. Shaft of the ulna. 2. Greater sigmoid notch. 3. Lesser sigmoid notch, with which the head of the radius is articu- lated. 4. Olecranon process. 5. Coronoid process. 6. Nutrient foramen. 7. The sharp ridges upon the two bones to which the interosseous mem- brane is attached. 8. Capitulum ulna;. q. Styloid process. 10. Shaft of the radius. 11. Its head surrounded by the smooth border for articulation with the orbicular ligament. 12. Neck of the radius. 13. Its tubercle. 14. The oblique line. 15. Lower extremity of the bone. 16. Styloid pro- cess. 144 internal surface is covered in for the greater part of its extent by the flexor profundus digitorum. The anterior border is rounded, and gives origin by its lower fourth to the pronator quadratus. The 'posterior is prominent, and affords attachment to the tendinous ex- pansion common to llie flexor carpi ulnaris, extensor carpi ulnaris, and flexor profundus digitorum ; expanding at the upper extremity into the triangular subcutaneous surface of the olecranon. The external or radial border is sharp and prominent, for the attach- ment of the interosseous membrane. The lower extremity terminates in a small rounded head, capi- tulum ulna;, from the side of which projects the styloid process. The latter presents a deep notch at its base for the attachment of the apex of the triangular interarticular cartilage, and by its point gives attachment to the internal lateral ligament. On the posterior sur- face of the head is a groove, for the tendon of the extensor carpi ulnaris ; and on the side opposite the styloid process a smooth sur- face, for articulation with the side of the radius. Development.—By three centres ; one for the shaft, one for the inferior extremity, and one for the tip of the olecranon. Ossification commences in the ulna during the eighth week ; the ends of the bone are cartilaginous at birth. The centre for the lower end appears at about the fifth, that for the tip of the olecranon about the tenth, year. The upper epiphysis joins the shaft about the six- teenth year, and the lower epiphysis joins about the twentieth. Articulations.—With two bones ; humerus and radius ; it is separated from the cunei- form bone of the carpus by the triangular interarticular cartilage. Attachment of Muscles. —To thirteen: by the ole- cranon to the triceps, one head of the flexor carpi ulnaris, and anconeus; by t\\ecorouoidpi-o- cess, bracliialis anticus, pro- nator radii teres, flexor sub- limis digitorum, and flexor profundus digitorum ; by the shaft, flexor profundus digi- torum, flexor carpi ulnaris, pronator quadratus, supinator brevis, anconeus, extensor carpi ulnaris, extensor ossis metacarpi pollicis, extensor secundi internodii pollicis, and extensor indicis. ULNA. Fig. 132.—Bones of the fore-arm, seen on their posterior as- pect. 1. Shaft of the ulna. 2. Olecranon process. 3. Border of the great sigmoid notch. 4. Ridge on radius and ulna for the interosseous membrane. 5. Capi- tulum ulnae. 6. Sty- loid process. 7. Shaft of the radius. 8. Its head. 9. Neck. 10. Tuberosity, n. Lower extremity of the bone. 12. Ridge separating the ten- dons of the extensors in their passage to the dorsum of the hand. 13. Styloid process. PLATE 10. •Flexor sublimis digitorum Pronator teres Flexor sublim. diy Supinator longus. Groove for ext. ossis. Groove for ext. primi. RADIUS. ‘45 RADIUS. The radius is the rotatory bone of the fore-arm ; it is divisible into a shaft and two extremities : unlike the ulna, its upper extremity is small, and merely accessory to the formation of the elbow-joint; while the lower extremity is large, and forms almost solely the joint of the wrist. The upper extremity presents a rounded head, depressed on its upper surface into a shallow cup for articulation with the capitellum of the humerus. Around the margin of the head is a smooth articular surface which is broad on the inner side, where it articulates with the lesser sigmoid notch of the ulna, and narrow in the rest of its circumference, to play in the orbicular ligament. Beneath the head is a constricted circular neck; and beneath the neck, on its inter- nal aspect, a prominent process, the tuberosity. The surface of the tuberosity is partly smooth and partly rough : rough behind, where it receives the attachment of the tendon of the biceps ; and smooth in front, where a bursa is interposed between the tendon and the bone. The shaft of the bone is prismoid, and presents three surfaces. The anterior surface is somewhat concave superiorly, where it lodges the flexor longus pollicis ; and Hat below, where it supports the pronator quadratus. At about the upper third of this surface is the nutrient foramen, which is directed upwards. The posterior surface is round above, where it supports the supinator brevis muscle, and marked below by several shallow oblique grooves, which afford attachment to the extensor muscles of the thumb. The external sur- face is round and convex, and marked in its middle by a rough impression for the insertion of the pronator radii teres ; it is separated from the anterior surface below by a rounded border, and above by a distinct ridge which runs forwards on to the anterior surface of the bone, and terminates in the lower part of the tuberosity ; this is called the oblique ridge, and gives attachment to the flexor sublimis digitorum. On the inner margin is a sharp and prominent crest, which gives attachment to the interosseous membrane. The lower extremity of the radius is broad and triangular, and provided with two articular surfaces ; one at the side of the bone, which is concave to receive the rounded head of the ulna ; the other at the extremity, and marked by a slight ridge into two facets, one external and triangular, corresponding with the scaphoid ; the other square, with the semilunar bone. At the outer side of the extremity is a strong conical projection, the styloid process, which gives attach- ment by its base to the tendon of the supinator longus, and by its apex to the external lateral ligament of the wrist-joint. The inner edge of the terminal articular surface affords attachment to the base of the triangular interartieular fibro-cartilage of the wrist-joint. Immediately in front of the styloid process is a groove, which lodges the tendons of the extensor ossis metacarpi pollicis and ex- CARPUS. 146 tensor primi internodii; and, behind the process, a broader groove, frequently divided by a slight ridge, for the tendons of the extensor carpi radialis longior and brevior ; behind this is a prominent ridge, and a deep narrow groove, for the tendon of the extensor secundi internodii pollicis ; and internal to this, another broad groove for the tendons of the extensor communis digitorum, and extensor indicis: the ex- tensor minimi digiti running in a groove at the point of arti- culation of the radius and ulna. Development.—By three cen- tres ; one for the shaft, and one for each extremity. Ossifica- tion commences in the shaft soon after the humerus, and before the ulna. The inferior centre appears during the second year, the superior about the fifth. The upper epiphysis unites about puberty, the lower about the age of twenty. Articulations.—With four bones: humerus, ulna, scaphoid, and semilunar. Attachment of Muscles.— To nine : by the tuberosity to the biceps ; by the oblique ridge, supinator brevis, flexor sublimis digitorum ; by the anterior sur- face, flexor longus pollicis and pronator quadratus ; by the ex- ternal surface, pronator radii teres ; by the posterior surface, extensor ossis metacarpi pollicis and extensor primi internodii; and by the styloid process, supinator longus. Kio. 133.—Grooves at the back of the radius and ulna. 1. Radius. 2. Ulna. 3. Groove for extensor ossis metacarpi and extensor primi internodii pollicis. 4. Groove for extensor carpi radialis longior. 5. For extensor carpi radialis brevior. 6. For extensor secundi internodii pollicis. 7. For extensor communis digitorum and exten- sor indicis. 8. For extensor minimi digiti. 9. For extensor carpi ulnaris. CARPUS. The bones of the carpus are eight in number, arranged in two rows, consisting of four bones each : those of the proximal row, enumerating from the radial side, are the scaphoid, semilunar, cuneiform, and pisiform ; those of the distal row, in the same order, are the trapezium, trapezoid, os magnum, and unciform. With the exception of the semilunar, they all have the dorsal surface broad and convex, and the palmar contracted ; the semilunar differs from the rest, in that its dorsal surface is narrow and flattened PLATE II. Groove for ext. ossis, metae. poll., and ext. primi inttr- liod. poll. CARPUS. 147 and its palmar surface broad and convex. The proximal articulating surface is usually convex, and the distal concave. SCAPHOID.—This bone is named from bearing some slight resem- blance to the shape of a boat, being broad at one end, and narrowed like a prow at the opposite ; concave on one side, and convex on the other. If carefully examined, it will be found to present proxi- mally a large convex articular surface, which fits into the outer part of the cupped extremity of the radius ; distally it is bluntly pointed, and has two smooth surfaces, divided by a slight ridge, for articula- tion, the outer with the trapezium, and the inner with the trapezoid. Its internal (ulnar) surface is concave, and presents two articular facets, one shallow and crescentic for the semilunar, the other circu- lar and deeply excavated for receiving the head of the os magnum. The proximal portion of the palmar surface is depressed and concave ; the distal portion is raised above the level of the rest of the bone, forming a marked prominence called the tubercle, to which the an- terior annular ligament is attached. The dorsal surface is convex from side to side, contracted from above downwards, and grooved for the attachment of ligaments. The external surface is narrow, non-articular, and rough for the attachment of fibres of the external lateral ligament. Recognition.*—To ascertain the hand to which the bone belongs : —hold it with the tubercle upwards, and the smooth, convex, proxi- mal surface directed backwards ; the narrow, non-articular, external surface will point to the hand to which the bone belongs. Articulations.—With five bones : radius, semilunar, trapezium, trapezoid, and os magnum. Attachment of Muscles.—No muscles are attached directly to this bone. SEMILUNAR.—This bone may be known by its crescentic figure. The dorsal surface is narrow and fiat, the palmar broad and rounded. The other surfaces are all articular ; they are as follows :— The proximal, large and convex, occupies the second depression on the inferior articulating surface of the radius ; the distal, concave, articulates with the head of the os magnum ; the external, crescentic, corresponds with a like surface on the scaphoid ; and the internal, nearly circular, articulates with the cuneiform, and by a small bevelled edge wTith the unciform. Sometimes it articulates also with the -unciform, in which case the last-named articulating sur- face is divided into two parts by a slight ridge. Recognition.—If the bone be held with the broad palmar sur- face upwards, and the convex proximal articulating surface directed backwards, the crescentic articular facet will point to the appro- priate hand. * In referring each bone to its appropriate hand the same system is to be followed throughout the series ; it consists in placing the bone in the position it occupies in the hand, namely, with the narrow palmar surface upwards, and the proximal surface (usually convex) looking backwards; the outer surface then points to the side to which the bone belongs. 148 CARPUS. Articulations.—With five bones : radiufe, scaphoid, os magnum, cuneiform, and unciform. Attachment of Muscles. —No muscles are attached to this bone. CUNEIFORM OR PYRAMIDAL.—This bone may be best dis- tinguished by an oval isolated facet, which articulates with the pisiform bone. Its ‘palmar sur- face is narrow and rough ex- ternally for the attachment of ligaments ; internally it presents the characteristic facet for the pisiform just referred to. The dorsal surface is broad and rough for ligamentous attach- ment. The distal end of the cuneiform bone lias a broad smooth surface for articulation with the unci- form ; the proximal surface is partly rough for the attachment of ligaments, and partly smooth for articulation with the trian- gular tibrocartilage. The outer side is marked by a circular facet corresponding to the one on the inner side of the semi- lunar ; the inner surface is rough, and gives attachment to the in- ternal lateral ligament of the wrist. Recognition.—Hold the bone with the pisiform articular facet upwards, and the 1 >road articular surface directed forwards ; the circular articular facet for the semilunar will point to the hand to which the bone belongs. Articulations.—With three bones : semilunar, pisiform, and unciform; and with the triangular fibrocartilage of the wrist- joint. Attachment of Muscles.—To none. PISIFORM.—This bone may be recognised by its small size, and by the possession of only one articular facet. Examined carefully, it will be observed to present four sides and two extremities ; one side is articular, the smooth facet approaching nearer to the proximal than to the distal extremity. The side opposite to this is rounded ; the remaining sides are, one slightly concave, the other slightly convex. Recognition.—If the bone be held with the articular surface directed downwards, and the overhanging portion pointing forwards, Fig. 134.—Diagram showing the dorsal sur- face of the bones of the carpus, with their articulations. The right hand:—r. Lower end of radius, u. Lower end of ulna. f. Interarticular flbroeartilage, attached to the styloid process of the ulna, and to the margin of the articular surface of the radius, s. Scapiioid bone. l. Semilunar, p. Pisiform, t. Trapezium, t. Trapezoid. m. Os magnum. u. Unciform. The figures both on the carpal and metacarpal bones refer to the number of bones with which they articulate. PLATE 12. Abd. min. dig. Flex, brev.- dig. min. Abd. j>olllc. Flex. brev. poll. — Extensor ossis nietacarpi. Opponens pollicls. ■ Abductor poilicis. the concave border will point to the hand to which the bone belongs. Articulations.—With the cuneiform bone only. Attachment of Muscles.—To two : flexor carpi ulnaris, and abductor minimi digiti; and to the anterior annular ligament. TRAPEZIUM.—This bone may be distinguished by a deep groove for the tendon of the flexor carpi radialis muscle, and by the saddle- shaped distal articular facet. Its 'palmar surface is marked by this groove, and by a prominent tubercle which overhangs it, which gives attachment to the abductor, flexor brevis, and flexor ossis metacarpi pollicis muscles, and to the anterior annular ligament. The proximal extremity of the trapezium has a facet for articulation with the scaphoid, and its distal extremity one of large size, concave from side to side, convex from above downwards, for articulation with the metacarpal bone of the thumb. Internally it presents two articular facets—the upper, large and concave, for the trapezoid ; the lower, small and flat, for the extremity of the second metacarpal bone. CARPUS. 149 Fig. 135.—Bones of the carpus of the right hand, separated so as to show the form of the individual bones, s. Scaphoid: the letter is placed over the surface which articulates with the radius. 1. Its dorsal sur- face. 2. Surface to articulate with the trapezium and trapezoid, the two facets divided by a ridge. 3. Concave articulating surface for the head of the os magnum, l. Semi- lunar : the letter is placed over the surface which articulates with the radius. 4. Surface to articulate with the scaphoid. 5. Surface to arti- culate with the head of the os magnum. 6. Border of the surface which articulates with the unciform, c. Cuneiform. 7. Surface to articulate with the semilunar. 8. Surface to articulate with the unciform, p. Pisiform. 9. Articular facet. t. Trapezium : the letter is placed on the surface which articulates with the sca- phoid. 10. Surface to articulate with the trapezoid. 11. Articulating surface for the metacarpal bone of the index finger. 12. Articulating surface for the meta- carpal bone of the thumb, tz. Trapezoid. 13. Articulating surface for the sca- phoid. 14. Articulating surface for the os magnum, m. Os magnum : the letter is placed on the head of the bone. 15. Rough surface of the dorsum of the bone. 16. Articulating surface for the unciform. 17. Articulating surface for the meta- carpal bone of the middle finger, u. Unciform : the letter is placed on the surface which articulates with the semilunar and cuneiform. 18. Articulating surface for the ring finger. 19. Articulating surface for the little finger. 20. Rough point forming part of the free border of the carpus. Its dorsal and external surfaces are rough for ligamentous attach- ments. Recognition.—If the bone be held with the grooved surface up- wards, and the surface with two facets forwards, the saddle-shaped surface will point to the hand to which the bone belongs. Articulations.—With four bones : scaphoid, trapezoid, and two first metacarpals. Attachment of Muscles.—To three : abductor pollicis, flexor brevis pollicis, and flexor ossis metacarpi pollicis. 150 CARPUS. TRAPEZOID.—This bone is small, oblong, quadrilateral, and bent near its middle. Its dorsal surface is wide and convex, its palmar very narrow and flattened. It has four articular surfaces sepa- rated by slight ridges ; the proximal of these is quadrilateral, and articulates with the scaphoid ; the distal one is saddle-shaped for the second metacarpal bone ; the internal surface is smooth and concave for the os magnum, and the external is convex for the trapezium. Recognition.—Hold the bone with the narrow free surface up- wards, and the saddle-shaped surface looking forwards ; the convex articular surface will point to the appropriate hand. Articulations.—With four bones : trapezium, os magnum, sca- phoid, and second metacarpal. Attachment of Muscles.—Part of the flexor brevis pollicis. OS MAGNUM.—This is the largest bone of the carpus; it is divisible into a head or proximal, and a body or distal extremity. The rounded head articulates by its proximal and external surfaces with the semilunar and scaphoid bones. Its palmar and dorsal sur- faces are both rough; the latter being square and flat, the former rounded and prominent. Its distal extremity is divided into three small facets for articulation with the second, third, and fourth metacarpal bones ; its internal surface is rough distally for an interosseous ligament, smooth proximally for articulation with the unciform. By its external surface it articulates by means of a small facet with the trapezoid, and proximal to this facet is a rough space for another interosseous ligament. The proximal artioular surface encroaches on the external surface but not on the internal, so that the former is easily identified by this peculiarity. Recognition.—If the bone be held with the flat and rough dorsal surface downwards, and the head directed backwards, the side of the head on to which the proximal articular facet is continued will point to the appropri- ate hand. Articulations.—With seven bones: scaphoid, semilunar, trapezoid, unci- form, and the second, third, and fourth metacarpal bones. Flo. 136.—Left hand viewed on its anterior or palmar aspect. 1. Scaphoid bone. 2. Semilunar. 3. Cuneiform. 4. Pisiform. 5. 1 rapezium, 6. Groove in the trapezium which lodges the ten- don of the flexor carpi radialis. 7. Trapezoid. 8. Os magnum. 9. Unciform. 10, 10. The five metacarpal bones. 11, n. First row of phalanges. 12, 12. Second row. 13, 13. Third row, or un- gual phalanges. 14. First pha- lanx of the thumb. 15. Second and last phalanx of the thumb. PLATE 13. Ext. sec. inter, poll. F.xt.. primi inter, poll. METACARPUS. Attachment of Muscles.—Part of the flexor brevis pollicis. UNCIFORM.—This is a triangular-shaped bone, remarkable for a long and curved process, which projects from its palmar aspect. The palmar surface is free, and is distinguished by the hooked process just mentioned ; the dorsal surface is broad and rough. Its distal extremity presents a double articular surface for the fourth and fifth metacarpal bones ; its proximal extremity is convex for articulation with the semilunar ; externally it has two facets, with an intervening rough space, these being for articulation with the os magnum ; and internal It/ it has an oblong smooth facet for the cuneiform, and below this a rough edge for attachment of ligaments. Recognition.—If the bone be held with the uncinate process upwards, and the double facet forwards, the two small articular surfaces, with the intervening rough portion, will point to the ap- propriate hand. Articulation.—With five bones : semilunar, os magnum, cunei- form, and fourth and fifth metacarpals. Attachment of Muscles.—To two : flexor ossis metacarpi minimi digiti and flexor brevis minimi digiti; and to the anterior annular ligament. Development of the Carpus.—The bones of the carpus are each developed by a single centre ; they are cartilaginous at birth. Ossi- fication commences towards the end of the first year in the os magnum and unciform ; at the end of the third year, in the cunei- form ; during the fifth year, in the trapezium and semilunar ; during the sixth, in the scaphoid ; eighth, in the trapezoid ; and twelfth, in the pisiform. The latter bone is the last in the skeleton to ossify ; it is, in reality, a sesamoid bone of the tendon of the flexor carpi ulnaris. The number of articulations which each bone of the carpus main- tains with surrounding bones may be expressed in figures, which will facilitate the student’s recollection ; the cipher for the first row is 5531, and for the second 4475. Tlie bones of the metacarpus are five in number. They are long bones, divisible into a head, shaft, and base. The head is rounded at the distal extremity, forming an articular surface which extends farther on the front than on the back of the bone ; each lateral aspect presents a small tubercle with a pit below it for the attachment of the lateral ligaments of the meta- carpo-phalangeal joint. The shaft is prismoid ; its posterior surface, upon which the extensor tendon lies, is flat; its anterior surface presents a ridge dividing two sloping surfaces for the attachment of the interossei muscles. The base is irregularly quadrilateral, and rough for the insertion of tendons and ligaments ; it presents three articular surfaces : one at each side for adjoining metacarpal bones, and one at the extremity for the carpus. METACARPUS. 152 The metacarpal bone of the thumb is one-third shorter than the rest, flattened and broad on its dorsal aspect, and convex on its palmar side ; the articular surface of the head is not so round as that of the other metacarpal bones ; and the base has a single proximal saddle- shaped surface, to articulate with the corresponding surface of the trapezium. It has no lateral facets. The metacarpal bones of the different fingers may be distinguished by certain special characters. The base of the metacarpal bone of the index finger is the largest of the four, and presents three articular facets at its proximal extremity for the trapezium, trapezoid, and os magnum, and one on its ulnar side for the third metacarpal. It may most readily be identified by its proximal articular surface being divided into two, so as to present a notched appearance. That of the middle finger may be distinguished by a rounded projecting process at the radial side of its base (styloid process) for the attach- ment of the tendon of the extensor carpi radialis brevior, and two small circular facets on its ulnar lateral surface. The base of the metacarpal bone of the ring finger is small and square, and has two small circular facets on the radial side to correspond with those of the middle metacarpal, and one on the ulnar side for the metacarpal of the little finger. The metacarpal bone of the little finger has only one lateral articular surface, namely, on the radial side. Development.—By two centres ; one for the shaft, and one for the digital extremity, with the exception of the metacarpal bone of the thumb, the epiphysis of which, like that of the phalanges, occupies the carpal end of the bone. Ossification of the metacarpal bones commences in the embryo during the eighth or ninth week, that is, soon after the bones of the fore-arm. The epiphyses make their appearance at the end of the second or early in the third year, and the bones are completed at twenty. Articulations.—The first with the trapezium ; second, trapezium, trapezoid, os magnum, and middle metacarpal; third or middle, os magnum, and adjoining metacarpal bones ; fourth, os magnum, unci- form, and adjoining metacarpal bones; fifth, unciform, and meta- carpal bone of the ring finger. Each bone also articulates with its appropriate proximal phalanx. Attachment of Muscles.—To the metacarpal bone of the thumb, three, flexor ossis metacarpi, extensor ossis metacarpi, and first dorsal interosseous ; index finger, six, extensor carpi radialis longior, flexor brevis pollicis, flexor carpi radialis, first and second dorsal and first palmar interosseous ; middle finger, six, extensor carpi radialis bre- vior, flexor brevis pollicis, flexor carpi radialis, adductor pollicis, second and third dorsal interosseous ; ring finger, three, third and fourth dorsal interosseous, and second palmar ; little finger, four, extensor carpi ulnaris, flexor ossis metacarpi minimi digiti, fourth dorsal and third palmar interosseous. METACARPUS. PHALANGES. PHALANGES. The phalanges (internodia) are the hones of the fingers ; they are named from their arrangement in rows, and are fourteen in number, three to each finger, and two to the thumb. In each finger the proximal phalanx is the longest, and the distal phalanx the shortest. In conformation they are long hones, divisible into a shaft and two extremities. The shaft is compressed from before backwards, convex on its posterior surface, and fiat with raised edges in front. The meta- carpal extremity or base in the first row is a simple concave articular surface ; that in the other two rows a double concavity, separated by a slight ridge. The digital extremities of the first and second row present a pulley-like surface, concave in the middle,'and convex at each side. The ungual extremity of the last phalanx is broad, rough, and expanded into a semilunar crest. Development.—Bv two centres; one for the shaft, and one for the base. Ossification commences (during the eighth week) in the third or ungual phalanges, then in the first, and lastly in the second. The epiphyses of the first row appear during the third or fourth year, those of the second row during the fourth or fifth, and of the last during the sixth or seventh. The phalanges are perfected by t lie twentieth year. Articulations.—The first row, with the metacarpal bones and second row of phalanges ; the second row, with the first and third ; the third, with the second row. Attachment of Muscles.—To the base of the first phalanx of the thumb four muscles, abductor pollicis, flexor brevis pollicis, adduc- tor pollicis, and extensor primi internodii; to the second phalanx, two, flexor longus pollicis, and extensor secundi internodii. To the first phalanx of the second, third, and fourth fingers, one dorsal and one palmar interosseous ; to that of the little finger, abductor minimi digiti, flexor brevis minimi digiti, and one palmar interosseous. To the second phalanges, flexor sublimis and extensor communis digi- torum ; to the last phalanges, flexor profundus and extensor communis digitorum. PELVIS AND LOWER EXTREMITY. The bones of the pelvis are the two ossa innominata, the sacrum, and the coccyx, forming the pelvic girdle; and those of the lower ex- tremity, the femur, patella, tibia and fibula, tarsus, metatarsus, and phalanges. OS INNOMINATUM. The os innominatum (os coxae) is an irregular, flat bone, consisting in the young subject of three parts, which meet at the acetabulum. Hence it is described in the adult as divisible into three portions, 154 OS INNOMINATUM. ilium, ischium, and pubes. The ilium is the superior, broad, and expanded portion which forms the prominence of the hip, and arti- culates with the sacrum. The ischium is the inferior and strong part of the bone on which the body rests in sitting. The pubes is that portion which forms the front of the pelvis, and gives support to the external organs of generation. The Ilium may be described as divisible into an internal and external surface, a crest, and an anterior and posterior border. The internal surface is bounded above by the crest, below by a prominent line, the pectineal line, and before and behind by the anterior and posterior border. It is concave and smooth for the anterior two-thirds of its extent, and lodges the iliacus muscle. The posterior third is rough, for articulation with the sacrum, and divided by a deep groove into two parts ; an anterior or auricular Fio. 137.—Os innominatum of the right side. 1. Ilium; its external surface. 2. Ischium. 3. Pubes. 4. Crest of the ilium. The * is situated upon the widest portion of the crest of the ilium. 5. Middle curved line. 6. Inferior curved line. 7. Surface for the gluteus maximus, and superior curved line. 8. Anterior superior spinous process. 9. Anterior inferior spinous process. 10. Posterior superior spinous process, n. Posterior infe- rior spinous process. 12. Spine of the ischium. 13. Great sacro-ischiatic notch. 14. Les- ser sacro-iscliiatic notch. 15. Tuberosity of the ischium, showing its three facets. 16. liamus of the ischium. 17. Superior ramus of the pubes. 18. Inferior ramus of the pubes. portion, shaped like the pinna of the ear, and coated by cartilage in the fresh bone ; and a posterior portion, very rough and uneven, for the attachment of the posterior sacro-iliac ligaments. The external surface (dorsum of the ilium) is uneven, partly convex, and partly concave : it is bounded above by the crest; below by a prominent arch, which forms the upper margin of the acetabulum ; and, before and behind, by the anterior and posterior border. At the posterior part, a rough line marks off a triangular area which gives attachment to the gluteus maximus ; the line is continued anteriorly into the outer lip of the crest, and is called the superior or posterior curved line. Near the middle of this surface is a second ridge which is called the middle curved line; it commences at about an inch and a half from the anterior extremity of the crest, and terminates in the upper part of the greater sacro-ischiatic notch. Below this is a third ridge called the inferior curved line, commencing just above the anterior inferior spine, and terminating at the lower part of the greater sacro-ischiatic notch. The surface included between the superior and middle curved lines gives origin to the gluteus medius muscle ; that between the middle and inferior curved lines, to the gluteus minimus ; and the rough interval between the inferior curved line and the arch of the acetabulum, to one head of the rectus femoris. The crest of the ilium is arched, and curved in direction like the italic letter f, being bent inwards at its anterior termination, and outwards at the posterior. It is broad for the attachment of three planes of muscle, which are connected with its external and internal border or lip, and with the intermediate space. On its outer lip, at about midway between the anterior superior spinous process and the summit of the crest, is a prominent tubercle, from which a strong ridge runs down to the acetabulum. This is the broadest part of the crest, and the descending ridge serves as a buttress in giving strength to the bone. The anterior border is marked by two prominences, the anterior superior spinous 'process, which is the anterior termination of the crest, and the anterior inferior spinous process; the first of these and the space beneath it give attachment to Poupart’s ligament and the sartorius muscle, the second to one head of the rectus. This border terminates inferiorly in the lip of the acetabulum. The posterior border also presents two prominences, the posterior' superior and posterior inferior spinous process, separated by a notch ; the former gives attachment to the oblique sacro-iliac ligament, the latter to the greater sacro-ischiatic ligament. Inferiorly this border is broad and arched, and forms the upper part of the great sacro-ischiatic notch. The Ischium is divisible into a thick and solid portion, the body, and a thin and ascending part, the ramus ; it may be considered also, for convenience of description, as presenting an external and internal surface, and three borders, posterior, inferior, and superior. The external surface is rough and uneven for the attachment of muscles ; and broad and smooth above, where it enters into the formation of the acetabulum. Below the inferior lip of the aceta- bulum is a notch which lodges the obturator externus muscle in its passage outwards to the trochanteric fossa of the femur. The internal surface is smooth, and somewhat encroached upon at its posterior border by the spine ; it is separated by the pectineal line from the concave inner surface of the ilium, and is chiefly occupied by the origin of the obturator internus. The posterior border of the ischium presents towards its middle a remarkable projection, the spine, which is directed backwards and inwards, and gives origin by its inner surface to two muscles, the coccygeus and levator ani. Immediately above the spine is a notch of large size, the great sacro-ischiatic, and below the spine, the lesser sacro-ischiatic notch ; the former, being converted into a foramen by OS INNOMINATUM. 155 156 the lesser sacro-ischiatic ligament, gives passage to the gluteal vessels and nerve, pyriformis muscle, pudic vessels and nerve, and ischiatic vessels and nerves ; the lesser, completed by the great sacro-ischiatic ligament, to the obturator internus muscle, the nerve which is dis- tributed to it, and internal pudic vessels and nerve. The inferior border is thick and broad, and called the tuberosity. The surface of the tuberosity is divided into two facets ; the upper and outer, for the origin of the semi-membranosus ; and the lower and inner, for the semi-tendinosus and biceps muscles. The inner margin of the tuberosity is bounded by a sharp ridge, which gives attachment to a prolongation of the great sacro-ischiatic ligament; and the outer margin by a prominent ridge, from which the quadratus femoris muscle arises. The superior border of the ischium is thin, and forms the lower circumference of the obturator foramen. The ramus of the ischium is continuous with the ramus of the pubes, and is slightly everted. The Pubes is divided into a central part or body, a horizontal ramus, and a descending ramus. The external surface of the body is rough for the attachment of muscles ; the internal surface is smooth, and enters into the formation of the cavity of the pelvis. The superior border is marked by a rough ridge, the crest; the inner termination of the crest is the angle; the outer end, the spine; the latter gives attachment to the inner end of Poupart’s ligament. The inner extremity of the body is the sym- physis ; it is oval and rough for the attachment of the articular cartilage. Running outwards from the spine is a sharp ridge, the pectineal line, which marks the brim of the true pelvis. The inferior border is broad, deeply grooved for the passage of the obturator vessels and nerve, and forms part of the boundary of the obturator foramen. The outer border of the body is sharp and thin, forming part of the margin of the obturator foramen, and giving attachment to the obturator membrane. The horizontal ramus extends from the body of the pubes to the junction of pubes and ilium ; their point of union is marked bv a rounded projection, the ilio-pubic eminence, which serves to separate the surface for the femoral vessels from another depression which overhangs the acetabulum and lodges the psoas and iliacus muscles. Behind this eminence runs the ilio-pectineal line, and on its inner side is a triangular area for the attachment of the pectineus muscle. The descending ramus of the pubes passes obliquely outwards, and is continuous with the ramus of the ischium. The inner border forms with the corresponding bone the arch of the pubes, and at its inferior part is everted, to give attachment to the crus penis. The ramus of the ischium and pubes together give attachment by their external sur- face to the adductor1 longus, brevis, and magnus muscles, the gracilis and obturator externus, and by their internal surface to the com- pressor urethrae, erector penis, transversus perinei, obturator internus, and levator ani. The acetabulum (cotyloid cavity) is a deep cup-shaped cavity, OS INNOMINATUM. PLATE 14. OS INNOMINATUM. situated at the point of union between the ilium, ischium, and pubes ; a little less than two-fifths being formed by the ilium, a little more than two-fifths by the ischium, the remaining fifth by the pubes. It is bounded by a deep rim or lip, broad and strong above, where most resistance is required, and marked in front by a deep notch, which is arched over in the fresh subject by a strong ligament, and transmits the nutrient vessels of the joint. At the bottom of the cup, and communicating with the notch, is a deep circular pit, which lodges a mass of fat, and gives attachment by its edges to the broad extremity of the ligamentum teres. The obturator or thyroid f '-amen (also called foramen ovale) is a large oval interval between th ’ 'schium and pubes, bounded by a narrow rough margin, to which a gamentous membrane is attached. The upper part of the foramen L increased in depth by the groove in the under surface of the os pubis, which lodges the obturator vessels and nerve. Development.—Bv eight centres : three principal, one for the ilium, one for the ischium, and one for the pubes; and five secondary, one, the Y-shaped piece, for the interval between the primitive pieces in the bottom of the acetabulum, one for the crest of the ilium, one (not constant) for the anterior and inferior spinous process of the ilium, one for the tuberosity of the ischium, and one (not constant) for the angle of the pubes. Ossification commences in the primitive pieces, immediately after that in the vertebra), firstly in the ilium during the eighth week, then in the ischium in the third month, and lastly in the pubes in the fourth or fifth month ; the first ossitic deposits being situated near the future acetabulum. At birth, the acetabulum, crest of the ilium, and ramus of the pubes and ischium, are cartilaginous. The rami of the ischium and pubes unite during the eighth year. The epiphyses appear about the time of puberty, that for the Y-shaped cartilage ossifying first; the three parts of the bone unite in the acetabulum at about the seventeenth or eighteenth year, and the bone is completed from the twenty-third to the twenty-fifth year. Articulations.—With three bones ; sacrum, opposite innominate, and femur. Attachment of Muscles and Ligaments.—To thirty-four muscles : to the ilium thirteen; by the outer Iff of the crest, obliquus externus for two-thirds its length, latissimus dorsi one-third, and tensor vaginae femoris its anterior fourth ; by the middle of the crest, internal oblique three-fourths its length, erector spinae the remaining fourth ; by the internal lip, transversalis three-fourths, and quadratus lumborum the posterior part of its middle third. By the external surface, gluteus medius, minimus, maximus, and one head of the rectus ; by the internal surface, iliacus ; by the anterior border, sar- torius, and the other head of the rectus ; by the edge of the great sacro-sciatic foramen, pyriformis. To the ischium fourteen ; by its external surface, adductor magnus and obturator externus ; by the internal surface, obturator internus and levator ani; by the spine, 158 PELVIS. gemellus superior, levator ani, coccygeus, and lesser sacro-ischiatic ligament; by the tuberosity, biceps, semi-tendinosus, semi-membran- osus, gemellus inferior, quadratus femoris, erector penis, and great sacro-ischiatic ligament; by the ramus, gracilis, and transversus perinei. To the os pubis sixteen; by its upper border, obliquus externus, obliquus internus, transversal is, rectus, pyramidalis, pec- tineus, and psoas parvus ; by its external surface, adductor longus, adductor brevis, gracilis, and obturator externus ; by its internal surface, levator ani and obturator internus ; aud by the ramus, adductor magnus, iscliio-cavernosus, and compressor urethrae. PEL The pelvis is formed by the union of four bones, namely, the two innominate bones, sacrum, and coccyx. It is divisible into a false Fig. 138.—Female pelvis. 1. Last lumbar vertebra. 2, 2. Intervertebral substance connecting the last lumbar vertebra with the fourth and sacrum. 3. Promontory of the sacrum. 4. Anterior surface of the sacrum, on which its transverse lines and foramina arc seen. 5. Tip of the coccyx. 6, 6. Iliac fossae, forming the lateral boundaries of the false pelvis. 7. Anterior 1 iperior spinous process of the ilium ; right side. 8. Anterior inferior spinous process. 9. Acetabulum, a. Notch of the acetabulum, b. Body of the ischium, c. Its tuberosity, d. Spine of the ischium seen through the obturator foramen, e. Pubes, r. Symphysis pubis. g. Arch of the pubes, h. Angle of the pubes, i. Spine of the pubes; the pro- minent ridge between h and i is the crest of the pubes, k, /.-. Pectineal line of the pubes. I, l. Pectineal line, to, to.. The prolongation of this line to the promontory of the sacrum. The line represented by h, i, k, k, l, l, and to, to, is the brim of the true pelvis, n. Ilio-pubic eminence, o. The smooth surface which supports the femoral vessels, p, p. Great sacro-iscliiatic notch. and true pelvis ; the former is the expanded portion, bounded on each side by the ilium, and separated from the true pelvis by the pectineal line. The true pelvis is all that portion which is situated below this line, which thus forms the margin or brim of the true pelvis, while the included area is called the inlet. The form of the inlet is heart-shaped, obtusely pointed in front at the symphysis pubis, expanded on each side, and encroached upon behind by a projection of the upper part of the sacrum, which is named the pro- montory. The cavity is somewhat encroached upon at each side by a smooth quadrangular plane of bone, corresponding with the internal surface of the acetabulum, and prolonged posteriorly into the spine of the ischium. In front are two fossue around the ob- turator foramina, for lodging the obturator internus muscle at each side. The inferior termin'’!* .. ef the pelvis is very irregular, and is termed the outlet. It is .ded, in front, by the convergence of the rami of the ischium and ubes, which constitute the arch of the pubes; on each side by the tuberosity of the ischium, and two irregular fissures formed by the greater and lesser sacro-iscliiatic notches ; and behind by the lateral borders of the sacrum, and the coccyx. The pelvis is placed obliquely with regard to the trunk of the body, the inner surface of the pubes being directed upwards, and serving to support the weight of the abdominal viscera. The base of the sacrum rises nearly four inches above the level of the upper border of the symphysis pubis, and the apex of the coccyx somewhat more than half an inch above its lower border. If a line were carried through the central axis of the inlet, it would impinge by one extremity against the umbilicus, and by the other against the middle of the coccyx. The axis of the inlet is, therefore, di- rected upwards and forwards, while that of the outlet points downwards and forwards, and corresponds with a line drawn from the upper part of the sacrum, through the centre of the outlet. The axis of the cavity represents a curve, corre- sponding very nearly with the curve of the sacrum, the extremities being indicated by "the central points of the inlet and outlet. A knowledge of the direction of these axes is important to the surgeon, as indicating the line in which instruments should be used in opera- tions upon the viscera of the pelvis, and the direction of force in the PELVIS. 159 Fig. 139.—Angle of inclination of the brim of the pelvis 1440 to the perpendicular,or 54° to the horizontal line. 160 FEMUlt. removal of calculi from the bladder ; and to the 'accoucheur, as explaining the course taken by the foetus during parturition. There are certain characteristic differences between the male and female pelvis. In the male the bones are thicker, stronger, and more solid, the cavity being deeper and narrower. In the female the bones are lighter and more delicate, the iliac fossae large, and the ilia expanded ; the inlet, outlet, and cavity are large, and the aceta- bula farther removed from each other ; the cavity is shallow, the tuberosities widely separated, the obturator foramina triangular, the sacrum broader and its curvature chiefly limited to the lower end, the coccyx more movable, and the span of the pubic arch greater. The precise diameter of the inlet and,outlet, and the depth of the cavity of the female pelvis, are important considerations to the accoucheur. Three diameters are usually described in each part of the true pelvis ; they are : (i) Antero-posterior or con jugate ; (2) Transverse ; and (3) Oblique. The following table shows llie comparative measure- ments in the male and female pelvis in inches :— Mali:. Female. Brim. Cavity. Outlet. Brim. Cavity. Outlet. Antero-posterior diameter. 4 4l 3V 4* S 5 Transverse diameter . 5 43 3i 5i S 4i Oblique diameter 4* 4* 4 5 5i 4i Tlie femur, the longest hone of the skeleton, is situated obliquely in the upper part of the lower limb, articulating by means of its head with the acetabulum, and inclining inwards as it descends, until it almost meets its fellow of the opposite side at the knee. In the female this obliquity is greater than in the male, in consequence of tlie great breadth of the pelvis. The femur is divisible into a shaft, a superior, and an inferior extremity. At the upper extremity is a rounded head directed upwards and inwards, and marked just below its centre by an oval depression for the ligamentum teres. The head is supported by a neck, which varies in length and obliquity with sex and period of life, being long and oblique in the adult male, shorter and more horizontal in the female and in old age. Externally to the neck is a large process, the trochanter major, which presents on its anterior surface an oval facet, for the attachment of the tendon of the gluteus minimus muscle ; and on its outer surface, an oblique line for the insertion of the gluteus medius. On its posterior side is a vertical ridge (quadrate line) for the attachment of the quadratus femoris muscle. At the inner side of the trochanter major is a deep pit, trochanteric or digital fossa, at the bottom of which the obturator externus muscle is FEMUR. PLATE 15. Obt. int. and gemelli. Great trochanter. Glut, minimus. Lig. teres. Spine for add. mag. FEMUR. l6j inserted. The upper border of the great trochanter gives attachment near its anterior extremity to the gemellus superior, obturator in- ternus, and gemellus inferior muscles, and a little behind this to the pyriformis muscle. Passing downwards from the trochanter major in front of the bone is an oblique ridge, which forms the inferior boundary of the neck, the spiral line, which if traced down- wards will be found to lead into the upper part of the linea aspera ; in well-marked specimens, two small tubercles will be found on it, one near the great trochanter, and the other lower down ; they are called the external and internal cermcal tubercles. Behind there is another oblique ridge, the intertrochanteric line, which terminates in a rounded tubercle on the posterior and inner side of the bone, the trochanter minor, for the insertion of the psoas and iliacus. The shaft of the femur is convex in front, and covered with muscles; and somewhat concave and raised into a rough and prominent ridge behind, the linea aspera. The linea aspera near the upper extremity of the bone divides into three branches. The anterior branch is con- tinued forwards in front of the lesser trochanter, and is con- tinuous with the spiral line; the middle is continued directly upwards into the lesser troch- anter ; and the posterior, broad and strongly marked, ascends to the base of the trochanter major. Towards the lower extremity of the bone the linea aspera divides into two ridges, which descend to the two condyles, and enclose a triangular space upon which rests the popliteal artery. The internal supra- condylar ridge is less marked than the external, and presents a broad and shallow groove for the passageof thefemoral artery. The nutrient foramen is situ- ated in or near the linea aspera, at about one-third from its upper extremity, and is directed obliquely from below upwards. The outer side of the shaft im- mediately above the condyles is verv much thicker than the . . . inner side, a point to be borne in mind m division oi the lemur lor the cure of knock-knee. 10. 140. — The right femur, seen on its an- terior aspect. 1. The shaft. 2. The head. 3. The neck. 4. Great trochan- ter. 5. Spiral line. 6. Lesser trochanter. 7. External con- dyle. 8. Inter- nal condyle, 9. Tuberosity ior the attach- ment of the external lateral ligament. 10. Fossa for the tendon of ori- gin of the pop- liteus muscle. 11. Tuberosity for the attach- ment of the internal lateral ligament. 12. Adductor spine. 162 FEMUR. Ihe lower extremity oi the femur is broad and porous, and divided by a smooth depression in front, and by a large fossa (inter- condylar fossa) behind, into two condyles. The external condyle is the broadest and most prominent, the internal the narrowest and longest; the difference in length depend- ing on the obliquity of the femur, in consequence of the separation of the two bones at tlieir upper extremity by the breadth of the pelvis. The difference in the length of the condyles has been ascer- tained to amount to about eight millimetres, this being the average of a hundred observations (H. E. Clark). The external condyle is marked on its outer side by a prominent tuberosity, which gives attachment to the external lateral ligament; and immediately beneath this is a fossa which lodges the tendon of origin of the popliteus. By the internal surface it gives attachment to the anterior crucial ligament of the knee-joint; and by its upper and posterior part, to the external head of the gastrocnemius and plantaris. The internal con- dyle projects on its inner side into a tuberosity, to which is attached the internal lateral ligament ; above this tuberosity, at the extremity of the internal supra-condylar ridge, is a tubercle for the insertion of the tendon of the adductor magnus ; and above the posterior surface of the condyle, a depression from which the internal head of the gastrocnemius arises. The outer side of the internal condyle is rough and concave, for the attachment of the posterior crucial ligament. The lower articular surface of the femur is divisible into three parts, the two condylar surfaces, and the patellar surface ; the latter is marked off from the two former by shallow depressions running from the free margins of the articulation into the upper part of the intercondylar notch. In addition to the true condylar surface, the internal condyle has on its anterior face a small oblique surface, interposed between the condylar and patellar surfaces. The patellar or trochlear surface is the anterior part of the articular surface ; its outer side extends higher up than its inner, and terminates by a more salient edge. Development.—By five centres ; one for the shaft, one for each extremity, and one for each trochanter. The femur is the first oi the long bones to show signs of ossification ; ossific matter is found immediately after the maxillae and before the termination of the second month of embryonic life. The secondary deposits take place in the following order : in the condylar extremity during the last month of foetal life ; in the head towards the end of the first year in the greater trochanter between the third and fourth year ; in the Fir;. 141.—Diagram of under surface of condyles of femur. PLATE 16. Obturator externus. Gluteus medius. Quadratus femoris. Gluteus maximus. Biceps femoris Vastus externus. Plantaris. Gastrocnemius. Popliteus. Gastrocnemius Inner tuberosity. PATELLA. lesser trochanter between the thirteenth and fourteenth. The lesser trochanter joins the shaft about the seventeenth year, the great trochanter in the eighteenth year, the head during the nineteenth year, and the lower extremity soon after twenty. Articulations.—With three hones: os innominatum, tibia, and patella. Attachment of Muscles.—To twenty-three: by the greater tro- chanter, to the gluteus medius and minimus, pyriformis, gemellus superior, obturator interims, gemellus inferior, obturator externus, and quadratus femoris ; by the lesser trochanter, to the common tendon of the psoas and iliacus. By the linea aspera, its outer lip, to the vastus externus, gluteus maxim us, and short head of the biceps ; by its inner lip, vastus interims, pectineus, adductor brevis, and adductor longus ; by its middle lip, adductor rnagnus ; by the anterior part of the bone, crurseus and subcrurseus ; by its condyles. gastrocnemius, plantaris, and popliteus. 163 PATELLA. The patella is a sesamoid bone, developed in the tendon of the quadriceps extensor muscle, and usually described as a bone of the lower extremity. It is heart-shaped in figure, the broad end being directed upwards, the apex- down wards ; the external surface is convex, and the internal divided by a ridge into two smooth surfaces, to articulate with the condyles of the femur. The external articular surface, corresponding with the external condyle, is the larger of the two, and serves to indicate the leg to which the bone belongs. Each surface pre- sents a faint transverse line near its lower end, another near its upper border, so as to divide them into three facets ; the internal surface has also a vertical line near its inner edge. To the upper border of the bone are attached the rectus femoris and crureus muscles, and to the upper part of the lateral margins the expanded tendons of the vastus externus and interims, and by the inferior pointed process it is attached, through means of a strong band called the ligamentum patella}, to the tubercle of the tibia. Development.—By a single centre, at about the middle of the third year. Articulations.-- With the two condyles of the femur. Attachment of Muscles.—To four: rectus, cruneus, vastus interims, vastus externus ; and to the ligamentum patellae. Fig. 142.—Patella of the right side. 1. Surface of articulation with the external condyle of the femur. 2. Sur- face of articulation with the internal con- dyle. 3. Apex of the bone. 164 TIBIA, TIBIA. I he tibia is the inner and larger bone of the leg; it is prismoid in form, and divisible into a shaft, an upper and lower extremity. The upper extremity, or head, is large, and expanded laterally into two tuberosities. On the upper surface the tuberosities arc smooth to articulate with the condyles of the femur ; the internal articular surface being oval to correspond with the internal condyle ; the external, broad and nearly circular. Between the two articular surfaces is a spinous process; and in front of and behind the spinous process a rough depression, giving attachment to the anterior and pos- terior crucial ligament and the two semilunar cartilages. Between the two tuberosities on the front aspect of the bone is a prominent elevation, the tubercle for the insertion of the 1 igamentu in patella), and i m mediately above the tubercle a smooth facet, corresponding with the bursa of the; ligamentum patellae. Posteriorly the tuberosities are separated by a de- pression called the popliteal notch, which gives attachment to part of the posterior crucial ligament, and part of the posterior ligament of Winslow. Upon the posterior and under part of the external tuberosity is an articular surface for the head of the lilmla; and upon the poste- rior part of the internal tuberosity a depression for the insertion of the tendon of the semi-membranosus muscle. The shaft of the tibia presents three surfaces. The internal is con- vex, and is subcutaneous through- out its lower three-fourths ; at the upper part, on a line with the tubercle of the tibia, it gives attachment to the tendons of the sartorius, gracilis, and semi- lendinosus muscles. The external is concave, and is occupied by the tibialis anticus muscle ; at its lower third it curves forwards towards the front of the bone, and supports the tendons of the tibialis anticus, extensor proprius hallucis, and extensor communis digitorum. The posterior is grooved for the attachment of muscles. Near the upper extremity of the posterior surface is an oblique ridge, the oblique line (or soleal ridge), for the attachment of the 3oleus muscle and fascia of the popliteus muscle ; and immediatelv Fig. 143.—Tibia and fibula of the right log, articulated and sgen from the front. 1. Shaft of the tibia. 2. Inner tuber- osity. 3. Outer tuberosity. 4. Spinous pro- cess. 5. Tu- bercle. 6. In- ternal or sub- cutaneous sur- face of the shaft. 7. Lower extremity of the tibia. 8. Internal malle- olus. 9. Shaft of the fibula. 10. Its upper extremity, n. Its lower ex- tremity, the external malle- olus. The sharp border between 1 and 6 is the crest of the tibia. PLATE 17. Inner tuberosity Gracilis. Sartorius. Semi-tendin. Peroneus longus. Peroneus brevis. Peroneus tertius. below the oblique line, tlie nutrient canal, which is directed down- wards. The triangular space above the oblique line is occupied by the popliteus muscle. The borders of the tibia are anterior, internal, and external. The anterior border is sharp and curved outwards in its upper two-thirds, and rounded and curved inwards below. It is known as the crest of the tibia, and, popularly, as the shin. The internal border is most prominent in the middle, and is rounded above and below ; it gives attachment to the internal lateral ligament of the knee-joint, and to the soleus and flexor longus digitorum muscles. The external border gives attach- ment throughout its whole length to the interosseous mem- brane, and divides below to enclose a triangular rough space, for the in- terosseous ligament between the lower end of tibia and fibula. The inferior ex- tremity of the bone is somewhat quad- rilateral, and pro- longed on its inner side into a large process, the internal malleolus. The inner surface of the malleolus, is smooth for articulation with the astragalus; at its tip is a small de- pression for the in- ternal lateral liga- ment of the ankle- joint. Behind the internal malleolus is a broad and shallow groove for lodging the tendons of the tibialis posticus and flexor longus digitorum ; and farther outwards another groove for the tendon of the flexor longus hallucis. At the outer side the surface is concave and triangular, rough above for the attachment of the interosseous ligament; and smooth below, to articulate with the fibula. On the extremity of the bone is a triangular smooth surface for articulation with the astragalus. Development.—By three centres ; one for the shaft, one for the upper extremity, including the tubercle, and one for the lower ex- tremity. Ossification commences in the tibia immediately after the TIBIA. 165 Fio. 144.— Tibia and fibula of the right leg articulated and seen from behind. 1. Articular depression for the external condyle of the femur. 2. Articular depression for the in- ternal condyle ; the prominence between the two is the spinous pro- cess. 3. Fossa and groove for the insertion of the tendon of the semi- membranosus. 4. Popliteal plane, for the origin of the popliteus. 5. Oblique line. 6. Nutrient fora- men. 7. Surface of the shaft on which the flexor longus digitorum rests. 8. Broad groove on the back part of the inner malleolus, fortlie tendons of the flexor longus digi- torum and tibialis posticus. 9. Groove for the tendon of the flexor longus hallucis. 10. Shaft of the fibula. The flexor longus hallucis lies on this surface of the bone ; its superior limit being marked by the oblique line im- mediately above the figure. 11. Styloid processes on the head of the fibula for the attachment of the tendon of the biceps. 12. Sub- cutaneous surface of the lower part of the shaft of the fibula. 13. External malleolus formed by the lower extremity of the fibula. 14. Groove on the posterior part of the external malleolus for the tendons of the peronei muscles. 166 femur ; the centre for the head of the bone appears either in the ninth month or soon after birth, and that for the lower extremity during the second year ; the latter is the first to join the diaphysis. The lower epiphysis joins the shaft about the twentieth year, and the bone is completed bv the union of the upper epiphysis about the twenty-fifth year. Two additional centres are sometimes found in the tibia, one for the tubercle, the other for the internal mal- leolus. Articulations.—With three bones : femur, fibula, and astragalus. Attachment of Muscles.—To ten; by the internal tuberosity to the semi-membranosus ; by the external tuberosity, tibialis anticus and extensor longus digitorum ; by the tubercle, ligamentum patellae ; by the external surface of the shaft, tibialis anticus ; by the posterior surface, popliteus, soleus, flexor longus digitorum, and tibialis pos- ticus ; and by the internal surface to the sartorius, gracilis, and semi- tendinosus. FIBULA. FIBULA. The fibula (Trcpovy, a brooch, from its resemblance, in conjunction with the tibia, to the pin of an ancient brooch) is the outer and smaller bone of the leg ; it is long and slender in figure, prismoid in shape, and, like other long bones, divisible into a shaft and two extremities. The upper extremity or head is thick and large, and depressed at the upper part by a concave surface, which articulates with the external tuberosity of the tibia. Externally to this surface is a thick and rough prominence, terminated behind by a styloid process for the attachment of the long external lateral ligament of the knee- joint, and for the insertion of the tendon of the biceps. The lower extremity is flattened from without inwards, and prolonged downwards beyond the articular surface of the tibia, forming the external malleolus. Its external side presents a rough and triangular surface, which is subcutaneous. On the internal sur- face is a smooth triangular facet to articulate with the astragalus, and a rough depression for the insertion of the interosseous ligament. Behind the articular surface and between it and the tip of the mal- leolus is a deep fossa which lodges the posterior slip of the external lateral ligament. The anterior border is thin and sharp, the posterior broad and grooved for the tendons of the peronei muscles. The shaft of the fibula is prismoid, and presents three surfaces ; external, internal, and posterior; and three borders. The external surface is the broadest of the three ; it commences on the anterior part of the bone above, and curves around it so as to terminate on its posterior side below. This surface is completely occupied by the two peronei muscles. The internal surface commences on the side of the superior articular surface, and terminates below by narrowing to a ridge which is continuous with the anterior border of the mal- leolus. It is marked along its middle by the interosseous ridge, which PLATE 18. Outer tuberosity. Flexor prop, hall TARSUS 167 is lost above and below in the inner border of the bone, and which gives attachment to the interosseous membrane. The posterior sur- face is twisted like the external ; it commences above on the posterior side of the bone, and terminates below on its internal side ; at about the middle of this surface is the nutrient foramen, which is directed downwards. The internal border commences superiorly in common with the interosseous ridge, and bifurcates interiorly into two lines, which bound the triangular subcutaneous surface of the external malleolus. The external border begins at the base of the styloid process of the head, and winds around the bone, following the direction of the corresponding surface. The posterior border, sharp and prominent, is lost inferiorly in the interosseous ridge. Recognition.—In order to recognise whether the bone belongs to the right or left side, it should be held with the head (known by the styloid process and terminal articular facet) upwards, and the pit at tlie back of the external malleolus directed towards the observer; the triangular subcutaneous area will then point to the side to which the bone belongs. Development*.—By three centres ; one for the shaft, and one for each extremity. Ossification commences in the shaft soon after its appearance in the tibia ; at birth the extremities are cartilaginous, an osseous deposit taking place in the inferior epiphysis during the second year, and in the superior during the fourth or fifth. The inferior epiphysis is the first to become united with the diaphysis, but the bone is not completed until nearly the twenty-fifth year. The epiphyses of all the long bones except the fibula unite with the diaphysis in the reverse order of their appearance ; but in the fibula, the lower epiphysis, which is the first to appear, is also the first to join the shaft. Articulations.—With the tibia and astragalus. Attachment of Muscles.—To nine : by the head, to the tendon of the biceps and soleus ; by the shaft, its external surface, peroneus longus and brevis ; internal surface, extensor longus digitorum, ex- tensor proprius hallucis, peroneus tertius, and tibialis posticus ; by the posterior surface, flexor longus hallucis. TARSUS. The bones of the tarsus are seven in number, viz., astragalus, os calcis, scaphoid, internal, middle, and external cuneiform, and cuboid. ASTRAGALUS.—-The astragalus (os tali) may be recognised by its rounded bead, a broad articular facet on its convex surface, and two articular facets, separated by a deep groove, on its concave surface. The bone is divisible into a superior and inferior surface, an ex- ternal and internal border, and an anterior and posterior extremity. 168 OS CALCIS. The superior surface is convex, and presents a large quadrilateral and smooth facet, somewhat broader in front than behind, to articulate with the tibia. The inferior surface is concave, and divided by a dee}) and rough groove (sulcus tali), which lodges a strong interosseous ligament, into two facets—the posterior large and quadrangular, the anterior smaller and elliptical—which articulate with the os calcis. The internal border, Hat and uneven, is marked by a pyriform arti- cular surface, limited to the upper half of this border, for the inner malleolus. The external presents a large triangular articular facet, extending the whole depth of the border, for the external malleolus, and is rough and concave in front. The anterior extremity presents a rounded head, encircled by a constriction somewhat resembling a neck ; the posterior extremity is narrow, and marked by a dee}) groove for the tendon of the Hexor longus hallucis. Recognition.—Hold the astragalus with the broad convex ar- ticular surface upwards, and rounded head forwards ; the large triangular lateral articular surface will point to the side to which the bone belongs. Articulations.—With four bones: tibia, fibula, os calcis, and scaphoid. OS CALCIS.—This bone may be known by its large size and oblong figure, by the massive portion which forms the heel, and by two articular surfaces, separated by a broad groove, upon its upper side. The os calcis is divisible into four surfaces, superior,inferior, external, and internal; and two extremities, anterior and ] losterior. The superior surface is convex behind and irregu- larly concave in front, where it presents two and sometimes three articular facets, divided by a broad and shallow groove (sulcus calcanei), for the inter- osseous ligament. surface is convex and rough, and bounded posteriorly by the two inferior tuberosities, of which the internal is broad and large, the external smaller and prominent. The external surface is convex and subcu- taneous, and is often marked towards its anterior third by two grooves, separated by a tubercle, for the tendons of the peroneus longus and brevis. The internal surface is concave and grooved for the tendons and vessels Fio. 145. — Dorsal surface of the left foot. 1. Astraga- lus ; its superior quadrilateral arti- cular surface, a. Head of the astra- galus which arti- culates with (4) the scaphoid bone. 3. Os calcis. 4. Scaphoid bone. 5. Internal cunei- form bone. 6. Middle cuneiform bone. 7. External cuneiform bone. 8. Cuboid bone. 9. Metatarsal bones of the first and second toes. 10. First phalanx of the great toe. n. Second phalanx of the great toe. 12. First phalanx of the second toe. 13. Second pha- lanx. 14. Third phalanx. PLATE 19. Peroneus tertius. Peroneus brevis., Ext. brev. digit.. SCAPHOID AND INTERNAL CUNEIFORM. 169 which pass into the sole of the foot. At the anterior extremity of this surface is a projecting process (sustentaculum tali), which supports the anterior articulating surface of the astragalus, and ■rves as a pulley for the tendon of the flexor longus hallucis. A.t the anterior extremity of the bone is a flat articular surface, nounted by a rough prominence, which affords one of the guides fie surgeon in the performance of Chopart’s operation. The rior extremity is prominent and convex, and constitutes the t rior tuberosity; it is smooth for the upper half of its extent, w,. re it corresponds with a bursa ; and rough below, for the inser- tion of the tenclo Achillis ; the lower part of this surface is bounded by the two inferior tuberosities. Articulations.—With two bones : astragalus and cuboid. In their articulated state a large oblique canal is situated between the astragalus and calcaneum, being formed by the apposition of the two grooves, sulcus tali and sulcus calcanei. This canal is called the sinus tarsi, and serves to lodge a strong interosseous ligament which ties the two bones together. Attachment of Muscles.—To eight: by the posterior tuberosity, to the tendo Achillis and plantaris ; by the inferior tuberosities and under surface, abductor hallucis, abductor minimi digiti, flexor brevis digitorum, flexor accessorius, and plantar fascia ; by the external surface, extensor brevis digitorum ; and by the sustentaculum tali, a few fibres of the tibialis posticus. SCAPHOID.—This bone may be distinguished by its boat-like figure, being concave on one side, and convex with three facets on the other. It presents for examination six surfaces ; three articular and three non-articular. The anterior surface is convex, and divided into three facets to articulate with the three cuneiform bones ; tlie posterior is concave to articulate with the rounded head of the astragalus. The superior surface is convex and rough, and the inferior somewhat concave and uneven. The external extremity is broad and rough ; the internal pointed and prominent, forming a tuberosity (tubercle of the scaphoid) which gives attachment to part of the tendon of the tibialis posticus. The external extremity sometimes presents a facet of articulation with the cuboid. Recognition.—If the bone be held so that the convex articular surface with three facets look forwards, and the convex non-articular surface upwards, the broad extremity will point to the side corre- sponding with the foot to which the bone belongs. Articulations.—With four bones: astragalus and three cunei- form, sometimes also with the cuboid. Attachment of Muscles.—To the tendon of the tibialis posticus. INTERNAL CUNEIFORM.—The internal cuneiform may be known by its irregular wedge shape, and by being larger than the two other bones which bear the same name. It presents for examination a convex and a concave surface, a long and a short articular border, and a small and a large extremity. The convex surface is internal and free, and assists in forming the MIDDLE CUNEIFORM. 170 inner border of the foot; it presents near its anterior extremity a smooth facet, into which part of the tendon of the tibialis anticns is inserted. The concave is external, and is marked by an inverted L- shaped articular surface, limited to its superior and posterior borders, for articulation with the middle cuneiform and second metatarsal bone. The long border is kidney-shaped, and articulates with the metatarsal bone of the great toe ; the short border is posterior, and articulates with the scaphoid bone. The small extremity (edge) is sharp, and is directed upwards ; the larger extremity (base) looks towards the sole of the foot, and is rounded into a broad tuberosity. Recognition.—Place the bone so that the small extremity may look upwards and the kidney-shaped articular border forwards ; the depression in the middle of the latter will point to the side corre- sponding with the foot to which it belongs. Articulations. -With four bones: scaphoid, middle cuneiform, and first two metatarsal bones. Attachment of Muscles. To the tibialis anticns and posticus and peroneus longus. MIDDLE CUNEIFORM.— The middle cuneiform is the smallest of the three ; it is wedge-shaped, the broad extremity being placed upwards, the sharp end down- wards in the foot. It presents for examina- tion four articular sur- faces and two free bor- ders. The anterior and posterior surfaces have nothing worthy of re- mark, excepting that the former extends the whole depth of the bone, while the latter is limited to its upper two-thirds. The inter- nal lateral surface has an L-shaped articular facet, extending along its upper and posterior margins for the interna cuneiform ; the externa has an articular facet limited to the posterior border for the external cuneiform bone. Recognition.—If the bone be held so that the Hat dorsal surface look upwards, its broadest edge being towards the holder, the articular surface, limited to the posterior border, will point to the side to which the bone belongs. Em. 146.—Sole of the left foot. 1. Inner tuberosity of tiie os calcis. 2. Outer tuberosity. * Posterior tuberosity. 3. Groove for the tendon of the flexor longus hallucis ; this figure indicates also the sustentaculum tali, upon which it, is placed. 4. Rounded head of tl 1 e astra- galus. 5. Scaphoid bone. 6. Its tubercle. 7. In- ternal cuneiform bone ; its broad extremity. 8. Middle cuneiform bone. 9. External cuneiform bone. 10,11. Cuboid bone. 11. Groove for the tendon of the penmens longus ; the prominence between this groove and figure 10 is the tuberosity of the bone. 12, 12. Metatarsal bones. 13, 13. First pha- langes. 14, 14. Second phalanges of the four lesser toes. 15, 15. Third or ungual phalanges of the four lesser toes. 16. Last phalanx of the great toe. EXTERNAL CUNEIFORM AND CUBOID. 171 Articulations.—With four bones : scaphoid, internal and external cuneiform, and second metatarsal bone. EXTERNAL CUNEIFORM.—The external cuneiform is intermediate in size between the two preceding, and placed, like the middle, with the broad end upwards, and sharp extremity downwards. It may be identified by a triangular articular facet on its outer side. It presents for examination four surfaces, and a superior and inferior extremity. The anterior surface is wedge-shaped and articular throughout its entire depth, for articulation with the third meta- tarsal. The 'posterior surface, also wedge-shaped, is articular only in its upper two-thirds, the lower part being rough for the attachment of ligaments. The external surface presents posteriorly a large smooth oval articular surface for the cuboid bone, and anteriorly at its upper angle a small facet for the base of the fourth metatarsal. The internal surface also has two facets separated by a rough de- pression, one along the posterior margin for the middle cuneiform, and the other at the upper and anterior angle of the bone for the base of the second metatarsal. The upper extremity is fiat, of an oblong square form, and bevelled posteriorly, at the expense of the outer surface, into a sharp edge ; the lower extremity forms a rounded ridge which serves for the attachment of the tibialis posticus and part of the fiexor brevis hallucis. Recognition.—Hold the bone with the fiat dorsal surface upwards and the narrower wedge-shaped articular surface directed backwards ; the large oval articular facet for the cuboid will then point to the side to which the bone belongs. Articulations.—With six bones : scaphoid, middle cuneiform, cuboid, and second, third, and fourth metatarsal bones. Attachment of Muscles.—To the flexor brevis hallucis and tibialis posticus. CUBOID.—The cuboid bone is irregularly cuboid in shape, and marked on its under surface by a deep groove for the tendon of the peroneus longus muscle. It presents for examination six surfaces, three articular and three non-articular. The non-articular surfaces are—superior, which is slightly convex, and assists in forming the dorsum of the foot; inferior, marked by a prominent ridge, the tuberosity, and a deep groove for the tendon of the peroneus longus ; and external, the smallest of the whole, and deeply notched by the commencement of the peroneal groove. The articular surfaces are —posterior, of large size, and concavo-convex, to articulate with the os calcis ; anterior, of smaller size, divided bv a slight ridge into two facets, for the fourth and fifth metatarsal bones ; and internal, a small oval articular facet, upon a large and quadrangular surface, for the external cuneiform bone. Recognition.—If the bone be held so that the plantar surface, with the peroneal groove, look downwards, and the largest articular surface backwards, the small non-articular surface, marked by the deep notch, will point to the side to which the bone belongs. METATARSAL BONES. 172 Articulations.—With four bones : os calcis, external cuneiform, fourth and fifth metatarsal bone, and sometimes the scaphoid. Attachment of Muscles.—To two: flexor brevis hallucis, and adductor hallucis. Upon a consideration of the articulations of the tarsus it will be observed that each bone articulates with four adjoining bones, with the exception of the calcaneum, which articulates with two, and the external cuneiform with six. Development.—By a single centre for each bone, with the excep- tion of the os calcis, which lias an epiphysis for its posterior tubero- sity. The centres appear in the following order: calcanean, sixth month ; astragalan, seventh month ; cuboid, ninth month ; external cuneiform, end of the first year ; internal cuneiform, during the third year ; middle cuneiform and scaphoid, during the fourth year. The epiphysis of the calcaneum appears at the tenth year, and is united with the diapliysis at about the fifteenth. METATARSAL BONES. These hones, five in number, are long bones, and divisible there- fore into a shaft and two extremities. The shaft is prismoid, and compressed from side to side ; the posterior extremity, or base, is wedge-shaped, to articulate with the tarsal bones, and with each other ; the anterior extremity presents a rounded head, circum- scribed by a neck, to articulate with the first row of the phalanges. Peculiar Metatarsal Bones.—The first is shorter and larger than the rest, and forms part of the inner border of the foot; its posterior extremity has no lateral facet, but presents a large kidney-shaped surface at its base, and an oval rough prominence beneath for the insertion of the tendon of the peroneus longus. The head of the bone has, on its plantar surface, two grooved facets, for sesamoid bones. To find the side to which the bone belongs, hold it with the base towards you and the convex surface upwards; the con- cavity of the kidney-shaped surface will then point to the appro- priate side. The second is the longest and largest of the remaining metatarsal bones ; it presents at its base an articular facet for the middle cunei- form bone, and has on its outer lateral surface four facets, two for the outer cuneiform and two for the third metatarsal. On its inner surface it has only one facet, for the internal cuneiform. If the bone be held with its head directed forwards and the convex surface of the shaft upwards, the four lateral facets will point to the side to which it belongs. The third may be known by two facets on the inner side of its base, corresponding with the second, and one on the outer side for the fourth metatarsal. It may be distinguished also by its smaller size. When held in the usual position, the side with the single1 lateral facet will indicate the foot to which the bone belongs. PLATE 20. PHALANGES. The fourth may be distinguished by its smaller size, and by having a single articular surface on each side of the base, the facet on the outer side being bounded distally by a very deep pit for an inter- osseous ligament. When held with the base backwards and dorsal surface upwards, the most prominent angle at the base will point to the foot to which the bone belongs. The fifth is recognised by its broad base, and by the large tuberosity at its outer side. Development.—Each bone by two centres ; one for the body and one for the digital extremity in the four outer metatarsal bones ; and one for the body, the other for the base, in the metatarsal bone of the great toe. In the latter toe there is frequently a second or distal epiphysis. Ossification appears in the shafts of these bones at about the eighth or ninth week ; the epiphyses appear in the heads of the metatarsals of the four outer toes about the third year, and in the base of that of the great toe in the fifth year, consolida- tion being effected at eighteen. Articulations.—With the tarsal bones by one extremity, and first row of phalanges by the other. The number of tarsal bones with which each metatarsal articulates from within outwards, is the same as between the bones of the metacarpus and carpus, one for the first, three for the second, one for the third, two for the fourth, and one for the fifth. Attachment of Muscles.—To fourteen: to the first, peroneus longus and first dorsal interosseous ; to the second, two dorsal inter- ossei and transversus pedis ; to the third, two dorsal and one plantar interosseous, adductor hallucis and transversus pedis ; to the fourth, two dorsal and one plantar interosseous, adductor hallucis and trans- versus pedis ; to the fifth, one dorsal and one plantar interosseous, peroneus brevis, peroneus tertius, abductor minimi digiti, flexor brevis minimi digiti, and transversus pedis. 173 PHALANGES. There are two phalanges in the great toe and three in the other toes, as in the hand. They are long bones, divisible into a central portion and extremities. The phalanges of the first row are convex above, concave on the under surface, and compressed from side to side. The proximal ex- tremity has a single concave articular surface, for the head of the metatarsal bone ; the distal extremity, a pulley-like surface, for the second phalanx. The second phalanges are short and diminutive, but somewhat broader than those of the first row. The third or ungual phalanges, including the second phalanx of the great toe, are flattened from above downwards, spread out later- ally at the base to articulate with the second toav, and at the oppo- site extremity to support the nail and the rounded extremity of the toe. SESAMOID BONES. Development.—By tivo centres ; one for the body and one for the metatarsal extremity. Ossification commences in these bones after the metatarsus, appearing firstly in the last phalanges, then in the first, and lastly in the middle row. The centres for the epiphyses appear during the fourth year for the first row, and the sixth year for the other two rows. The bones are completed at eighteen. Articulations.—The first row with the metatarsal bones and second phalanges ; the second, of the great toe, with the first pha- lanx ; of the other toes, with the first and third phalanges ; the third, with the second row. Attachment of Muscles.—To twenty-three: to the first, phalanges; great toe, innermost tendon of the extensor brevis digitorum, abductor hallucis, adductor hallucis, flexor brevis liallucis, and transversus pedis ; second toe, first and second dorsal interosseous and lumbri- calis; third toe, third dorsal and first plantar interosseous and lumbricalis ; fourth toe, fourth dorsal'and second plantar interosseous and lumbricalis ; fifth, toe, third plantar interosseous, abductor minimi digiti, flexor brevis minimi digiti and lumbricalis. Second phalanges : great toe, extensor longus hallucis, and flexor longus hallucis ; other toes, one slip of the common tendon of the extensor longus and extensor brevis digitorum, and flexor bye vis digitorum. Third pha- langes : two slips of the common tendon of the extensor longus and extensor brevis digitorum, and the flexor longus digitorum. SESAMOID BONES. These are small masses, cartilaginous in early life, osseous in the adult, developed in those tendons which exert a certain degree of force upon the surface over which they glide, or where, by continued pressure and friction, Ihe tendon would become a source of irritation to neighbouring parts, as to joints. The best example of a sesamoid bone is the patella, developed in the common tendon of the quad- riceps extensor, and resting against the front of the knee-joint. Be- sides the patella, there are four pairs of sesamoid bones constantly found, two on the metacarpo-phalangeal articulation of each thumb, and existing in the tendons of insertion of the flexor brevis pollicis, and two on the corresponding joint in the foot, in the tendons of the muscles inserted into the base of the first phalanx. In addition to these there is often a sesamoid bone on the metacarpo-phalangeal joint of the little finger > mid on the corresponding joint in the foot, in the tendons inserted into the base of the first phalanx ; there is ('lie also in the tendon of the peroneus longus muscle, where it glides through the groove in the cuboid bone ; sometimes in the tendons, as they wind around the inner and outer malleolus; in the psoas and iliacus, where they glide over the os pubis ; and in the external head of the gastrocnemius. T1 ie bones of the tympanum, as they belong to the apparatus of hearing, will be described with the anatomy of the ear. PART III. ARTHROLOGY. Articulations or joints are the means by which the bones of tbe skeleton are united together, the same terms being also applied to the union between cartilages when these are adapted for movement on each other, as, for instance, in the larynx. The connections between the bones may take place simply by the intervention of a small quantity of connective tissue, and the union be so close as to render movement impossible, forming an immovable joint, or Syn- arthrosis ; or the bones may be widely separated, and the substance lying between them and connecting them together may lie so yield- ing as to admit of a limited degree of movement in several direc- tions, forming a yielding joint, or Amphi-arthrosis. In all the articulations of the limbs, however, we find a more elaborate and perfect arrangement admitting of much freer motion, constituting a movable joint, or Diarthrosis. In the latter the expanded ends of the bones are coated by a thin layer of cartilage, are connected together by bands of fibrous tissue called ligaments, and are lubri- cated by the fluid secreted by a synovial membrane which lines the inner surface of the ligaments; in many joints, also, a disc of fibro-cartilage is interposed between the articular surfaces, and the cavity divided into two, the advantages of a double joint being thus secured. The structures entering into the composition of a joint are bone, cartilage, areolar and adipose tissue, elastic tissue, fibrous tissue, and synovial membrane ; the microscopic anatomy of these has been fully described in Part I. of this work, but it remains to point out their peculiar arrangement in the construction of joints. The articular ends of long bones are expanded and rendered either concave or convex, so as to fit each other ; they are formed of can- cellous tissue with an outer thin coating of dense bone. This layer of compact bone is called the articular lamella; it is distinguished from ordinary bone by the absence of Haversian canals, the large size of the lacunae, and by the canaliculi being few in number, and so short as not to communicate with those derived from neighbour- ing lacunae. The vessels of the cancellous tissue do not penetrate the articular lamella, but turn back in loops before reaching it. In some places the bones are produced into projecting processes which ARTHROLOGY, overhang the joint, affording protection against external injury, as well as giving greater leverage to the muscles ; this arrangement may he noticed in the elbow, ankle, and wrist joints'. The cartilage found in joints is of two kinds, hyaline and fibro* cartilage. The former is known as true articular cartilage, or carti- lage of incrustation ; it coats the articular surfaces of the bones, and is generally so arranged as to increase the depth of articular cavities and the prominence of articular convexities, being in the one case thickest at its edges, and in the other in the middle. Fibro-cartilage is in amphi-arthrodial joints the connecting medium binding the bones together ; in diarthrodial joints it forms encircling bands which deepen the articular cavities, or it occurs as concave discs (interarticular fibro-cartilages) which divide the joint into two parts, each part having its own synovial membrane. Areolar and adipose tissue are used for filling up the interstices in and around joints, so as to ensure the perfect adaptation of the articular surfaces to each other ; in joints (such as the knee) which received little protection from the surrounding muscles, the amount of fat found among the ligaments and beneath the superficial fascia is relatively very large. The ligaments which connect the bones together are for the most part formed of strong bands of white fibrous tissue, but in some few a slight admixture of yellow fibres may be observed, and those con- necting the laminae of the vertebrae (ligamenta subflava) are entirely formed of yellow or elastic tissue. In the joints possessing the freest movement the ligaments form a fibrous envelope which en- tirely surrounds and encloses the articular surfaces—these are called capsular ligaments; in those enjoying the next degree of mobility the ligaments exist as flattened bands arranged in front, behind, and at the sides of the articulation. Some few joints have ligamen- tous bands in their interior ; examples of these are the ligamentum teres of the hi}) and crucial ligaments of the knee ; they are en- closed in a tube formed of synovial membrane. The synovial membrane lines the whole of the interior of the joint, except where the articular cartilage is interposed ; it is smooth and glistening on the inner surface, rough externally where it becomes attached to the bones and ligaments ; it often forms folds, which project into the interior of the joint and contain masses of fat with loops of capillary vessels. Besides the structures which form the joints, others also contribute to keel) the articular ends of the bones in place, and to ensure due and smooth movement ; of these the most important are the m uscles and bursa;. The muscles not only act as the agents of motion, but are of essential service in maintaining the structures of the joint in their proper relative position, supporting the ligaments by their tonic contraction, and in some instances acting directly on the synovial membrane so as to prevent its becoming squeezed between the ends of the bones. In the shoulder-joint the tendon of a muscle passes through the synovial cavity, and in both that joint and the knee the tendons of certain muscles take the place of ligaments and are coated on their interior by synovial membrane. Bursae mucosae are closed synovial sacs, the structure of which has been described on a previous page. Some of them lie between the tendons of muscles and the ligaments of joints, and in this position often communicate with the cavities of those joints ; this being especially apt to occur with the bursa which lies between the capsule of the hip-joint and the united tendons of the psoas and iliacus. Bursae occur (i) between tendons and bones, (2) between tendons and ligaments, (3) between superficial bony prominences and the fascia) beneath the skin, (4) between contiguous tendons, and (5) between neighbouring bones. They are very numerous, about 140 being found in the human body. Superficial bursa are constantly found in the following positions :—In the head and neck they occur on each angle of the lower jaw, beneath the symphysis of the jaw, and on the salient angle of the thyroid cartilage. In the upper extremity, over the acromion process, on the external and internal condyles of the humerus, on the back of the olecranon, the styloid processes of the radius and ulna, and the dorsal and palmar surfaces of the metacarpo-phalangeal joints. In the lower extremity they are found on the anterior superior spine of the ilium, over the great trochanter, on the tuberosity of the ischium, the lower half and the upper and outer angle of the patella, on the outer and inner condyles of the femur, the outer and inner tuberosities of the tibia, the head of the fibula, the outer and inner malleoli, the posterior and inner face of the os calcis, and the dorsal surface of the articulations of the toes. The deep bursa lie between the tendons of muscles, or between the tendons and joints ; these are even more numerous than the .super- ficial ones, so that only a few of the more important will be mentioned here. These are the bursa beneath the deltoid, that between the tendon of the psoas and capsule of the hip-joint, one beneath the tendon of insertion of the triceps, one beneath the ligamentum patella), one between the gluteus maximus and vastus externus, one beneath the tendon of insertion of the biceps of the arm, and one between the tendon of insertion of the semi-membranosus and the inner head of the gastrocnemius. Besides these normal bursae, other accidental or pathological ones are formed wherever there is great pressure', as, for instance, on the parts of the foot which come in con- tact with the ground in club-foot, and on the ends of stumps after amputation. Blood-vessels.—The arteries distributed to a joint pass to all the structures excepting the cartilages, which are non-vascular; they frequently form fine circles round the edges of the cartilage, and are more especially abundant in the synovial membrane. Nerves.—Hilton formulated a law regarding the distribution of nerves to joints, which is as follows :—The same trunks of nerves, whose branches supply the groups of muscles moving a joint, furnish also a distribution of nerves to the skin over the insertion of the same muscle, and the interior of the joint receives its nerves from the same source.” BURS.B MUCOSiE. 177 ARTICULATIONS. 178 TABLE OF ARTICULATIONS. I. SYNARTHROSIS. Example. 1. Suture .... Tabular bones of skull. 2. Harmonia .... Union of bones of face. 3. Schindylesis . • • Vomer with rostrum of sphenoid. 4. Gomphosis .... Teeth with alveolar processes. 1. Complete union by fibro- cartilage II. AMPHI-ARTHROSIS. Symphysis pubis, and sacro-iliac joint. I ntervertebral substance. 2. Partial synovial cavity III. DIARTHROSIS. 1. Arthrodia . Sterno- and acromio - clavicular articulations. 3. Trochoides. 2. Ginglymus .... Ankle, elbow, knee. Odontoid process with atlas, and upper radio-ulnar joint. 4. Condylarthrosis Metacarpo- and metatarso - pha- langeal, wrist-joint. 5. Enarthrosis . . . Hip, shoulder. SYNARTHROSIS (avv, apOpuais, articulation) includes all those articulations in which there is no appreciable movement, the bones being united only by a small quantity of connective tissue, some- times described under the name of the sutural ligament. This class of joints includes all the articulations of the bones of the skull and face, excepting those of the lower jaw. There are three kinds of synarthrosis ; namely, Suture, Schindylesis, and Gomphosis. Suture (sutura, a seam) is the name given to a joint in which the edges of the bone are projected into fine irregular processes, which fit into the intervals between corresponding processes in the bone with which it joins, somewhat like the dove-tail joint in cabinet- work. Between the bones so articulating there is a small quantity of connective tissue, which in the young skull is continuous with the pericranium on the outside, and with the dura mater on the inside. Three varieties of suture are distinguished,—the Serrated, Harmonia, and Squamous. The serrated suture is formed by the union of two borders possessing serrated edges, as in the coronal, sagittal, and lambdoidal sutures. In these sutures the serrations are formed almost wholly by the external table, the edges of the internal table lying merely in apposition. The serrated suture is formed by the interlocking of the radiating fibres along the edges of the fiat ARTICULATIONS. 179 bones of the cranium during growth. A variation in the formation of the serrated suture is seen in the coronal suture, where the edge of the bone is bevelled at the expense of the inner table of the one bone, and of the outer table of the other at one part; and in another part these conditions are reversed. This condition is sometimes described under the name of sutura limbosa. The harmonia suture (aptlv, to adapt) is the simple apposition of contiguous surfaces, the surfaces being more or less rough. This suture is seen in the con- nection between the superior maxillary bones, or of the palate pro- cesses of the palate bone with each other. The squamous suture is formed by the overlapping of the lower border of the parietal bone, by the thin scale-like edge of the squamous portion of the temporal. Schindylesis (duction, adduction, and circumduction, but no axial rotation. Examples of this form are seen in the wrist- joint, and metacarpo-plialangeal and metatarso-phalangeal articula- tions. Enarthrosis (eV, in, ap6pu>a-is) is the most extensive in its range of motion of all the movable joints. From the manner of connection and form of the bones in this articulation, it is called the ball-and- socket joint. There are two instances in the body, namely, the hip and the shoulder. The ball-and-socket joint has a circular form ; and, in place of the four distinct ligaments of the ginglymus, is enclosed in a bag of ligamentous membrane, called capsular ligament. We may add to the preceding the carpo-metacarpal articulation of the thumb, although not strictly a ball-and-socket joint, from the great extent of motion which it enjoys, and from the nature of the ligament connecting the bones. Some authors make a special genus for this joint, under the title of articulation by reciprocal surfaces. MOVEMENTS OF JOINTS Tlie motions of joints may be referred to four heads, viz., Gliding, Angular movement, Circumduction, and Rotation. i. Gliding is the simple movement of one articular surface on another, and exists to a greater or less extent in all the joints. In the least movable joints, as in the carpus and tarsus, this is the only motion which is permitted. Gliding is, in certain joints, MOVEMENTS OF JOINTS. 181 accompanied by what is known as coaptation, that is, the successive application of different parts of an articular surface to its fellow, in the manner of a wheel rolling on the ground. This is well seen in the motion of the patella on the condyles of the femur. 2. Angular movement may be performed in four different direc- tions, either forwards and backwards, as in flexion and extension ; or inwards and outwards, constituting adduction and abduction. Flexion and extension are illustrated in the ginglymoid joint, and exist in a large proportion of the joints of the body. Adduction and abduction, conjoined with flexion and extension, are met with com- plete only in the most movable joints, as the shoulder, hip, and thumb. In the wrist and ankle, adduction and abduction are only partial. 3. Circumduction is most strikingly exhibited in the shoulder and hip joints ; it consists in the slight degree of motion which takes place between the head of a bone and its articular cavity, while the extremity of the limb is made to describe a large circle on a plane surface. It is also seen, but in a less degree, in the carpo-metacarpal articulation of the thumb, and the metaearpo-phalangeal articulation of the fingers and toes. 4. Rotation is the movement of a bone on its own axis, and is illustrated in the hip and shoulder, or better, in the rotation of the cup of the radius against the eminentia capitata of the humerus. Rotation is also observed in the movements of the atlas upon the axis, where the odontoid process serves as a pivot around which the atlas turns. ARTICULATIONS. The joints may be arranged, according to a natural division, into those of the trunk, those of the upper extremity, and those of the lower extremity. LIGAMENTS OF THE TRUNK. The articulations of the trunk are divisible into eleven groups, namely:— t. Of the vertebral column. 2. Of the atlas, with the occipital bone. 3. Of the axis, with the occipital bone. 4. Of the atlas, with the axis. 5. Of the lower jaw. 6. Of the ribs, with the vertebrae. 7. Of the costal cartilages, with the sternum, and with each other. 8. Of the ribs, with the costal cartilages. 9. Of the sternum. 10. Of the vertebral column, with the pelvis. 11. Of the pelvis. 182 L1GAMENTS OF THE VERTEBRAL COLUMN. i. ARTICULATIONS OF THE VERTEBRAL COLUMN.—The liga- ments connecting together the different pieces of the vertebral column, admit of the same arrangement as the vertebrae them- selves. Thus the ligaments Of tlie bodies, are the Anterior common ligament, Posterior common ligament, Intervertebral substance. Of the arches, Ligamenta suhtlava. Of the articular processes, Capsular ligaments, Synovial membranes. Of the spinous processes, Inter-spinous, Supra-spinous. Of the transverse processes, Inter-transverse. Bodies.—The anterior common ligament is a broad and ribbon- like band of ligamentous fibres, extending along the front sur- face of the verte- bral column, from the axis to the sac- rum, and becoming broader as it de- scends. It is in- timately connected with the interver- tebral substance, and less closely with the bodies of the vertebrae, in the dorsal region it is thicker than in the cervical and lumbar, and consists of a median and two lateral portions separated from each other by a series of openings for the passage of vessels. The ligament is composed of til ires of various lengths closely interwoven with each other ; the deeper and shorter crossing the intervertebral substance from one vertebra to the next; the superficial and longer fibres crossing three or four vertebrae. The posterior com- mon ligament is situ- ated in the spinal canal ; it lies on the posterior surface of the bodies of the vertebrae, and ex- tends from the axis to the sacrum. It is broad opposite the intervertebral substance, to which it is closely adherent; narrow and thick over the bodies of the vertebrae, from which it is Fio. 147.—Anterior ligament, of the vertebra;, and liga- ments of the ribs. 1. An- terior common ligament. 2. Anterior costo-vertebral or stellate ligament. 3. An- terior costo-transverse liga- ment. 4. Interarticular liga- ment connecting trie head of trie rib to the inter- vertebral substance, and separating the two synovial membranes of this articu- lation. Fig. 148.—A posterior view of the bodies of three dor- s;il vertebra;, eounected by their intervertebral sub- stance, 1, 1. The lamina; (2) have been sawn through near the bodies of the ver- tebras, and the arches and processes removed,in order to show (3) the posterior common ligament. Part of one of the openings in tlie posterior surface of the vertebra, for the trans- mission of the vena basis vertebrae, is seen at 4, by the side of the narrow and unattached portion of the ligament. LIGAMENTS OF THE VERTEERAL COLUMN. 183 separated by the veins of the body of each vertebra ; it thus conies to present a festooned or dentate margin. It is composed, like the anterior ligament, of shorter and longer fibres, arranged in a similar manner. It is broader above than below, the reverse of the anterior common ligament, and is thicker in the dorsal than in the cervical or lumbar region. At its upper end it is continuous with the posterior occipito-axial ligament. The intervertebral substance is a lenticular disc of fibro-carti- lage, interposed between the bodies of the vertebrae from the axis to the sacrum, and retaining them firmly in connection with each other. The discs vary in thickness in different parts of the column and at different points of the same disc, being thickest in the lumbar region, deeper in front than behind in the cervical and lumbar regions, and contribute to the formation of the natural curves of the vertebral column. The aggregate thickness of the intervertebral sub- stance has been estimated at one- fourth that of the entire vertebral column, exclusive of the sacrum and coccyx. When the intervertebral substance is bisected either horizontally or vertically, it is seen to be composed of a series of layers of fibro- cartilage mixed with fibrous tissue. The central part of each inter- vertebral disc is much softer than the rest; it has the appearance of pulp, and is so elastic as to rise above the level of the section as soon as its division is completed. Examined from the exterior, the layers are found to consist of fibres passing obliquely between the twro vertebrae, in one layer passing from left to right, in the next from right to left, alternating in each successive layer. Examined micro- scopically, the central pulp is found to be composed of fine fibrous tissue supporting cells some of which resemble those of cartilage ; it is generally regarded as a persistent part of the chorda dorsalis. The central pulp and several layers of fibres surrounding it, are separated from the bone of the vertebral bodies by a thin layer of cartilage. Arches.—The ligamenta sutflava are two thin planes of yellow' fibrous tissue, situated between the arches of the vertebrae, from the axis to the sacrum. From the imbricated position of the laminae, they are attached to the posterior surface of the vertebra below, and the anterior surface of the arch of the vertebra above, being separated from each other in the cervical region at the middle line by a slight interspace filled with areolar tissue. In the dorsal and lumbar regions they are continued for a little way on to the roots of the spinous processes, wdiere they unite with the interspinous ligaments and with each other. They counteract, by their elasticity, the efforts Pig. 149.—Diagram of an inter- vertebral disc divided vertically. At a, the pulpy centre ; at b, the fibrous ring; at c, the cartilagin- ous covering of the body of the vertebra; d, the periosteum. 184 LIGAMENTS OF THE VERTEBRAL COLUMN of the flexor muscles of the trunk ; and, preserving the upright posi- tion of the spine, limit the expenditure of muscular force. They are longest in the cervical and thickest in the lumbar region. The ligamenta subflava are continued in the cervical region on to the inner side, and in the dorsal and lumbar regions on to both anterior and inner sides of the articular processes, so as to form part of the capsules of the joints. Articular Processes.—The liga- ments of the articular processes of the vertebra} are thin capsules of white and yellow fibres which surround and enclose the synovial membrane; the latter being looser in the cervical than in the other regions of the spine. Spinous Processes. — The inter- spinous ligaments, thin and mem- branous, are extended between the spinous processes in the dorsal and lumbar region ; being thickest in the latter. They are in relation with the interspinous muscles at each side. The supraspinous ligament (Fig. 159) is a strong, fibrous cord, extending from the apex of the spinous process of the last cervical vertebra to the coccyx, and attached to each spinous process in its course. Like the anterior and posterior common ligaments, it is composed of fibres of unequal length, the deeper fibres passing from one vertebra to the next, the superficial fibres extending over several spinous processes. It is thickest in the lumbar region. The con- tinuation of this ligament upwards to the tuberosity of the occipital bone, constitutes the rudimentary ligamentum nucha} of man. The latter is strengthened, as in animals, by a thin slip from the spinous process of each cervical vertebra. At its lower termination the supraspinous ligament spreads out to cover the end of the spinal canal, exposed by the deficiency of the laminae of the lower sacral and coccygeal vertebrae. Transverse Processes.—The intertransverse ligaments are represented in the cervical region only by a few scattered fibres, in the dorsal region they are rounded cords, and in the lumbar region they are thin and membranous. Movements of the Spine.—Flexion and extension take place freely in the cervical and lumbar regions, but especially in the latter ; in the dorsal region these movements are very slight in consequence of the imbrication of the lamina} and the small amount of intervertebral substance. Rotation is free in the neck, but in consequence of the direction of the articular processes takes place round an oblique axis, the articular process of one side moving Fig. 150.—Internal view of tlie arches of three vertebra. To obtain this view the laminse have been divided through their pedicles. 1. One of the liga- rnenta subflava. 2. The capsu- lar ligament of one side. LIGAMENTS OF THE ATLAS AND OCCIPITAL BONE. 185 upwards and forwards, while the other travels downwards and backwards. In the dorsal region rotation is free (especially in the upper part), the movement taking place round an axial line running through the centre of the vertebral bodies. The articular processes of the lumbar region are so disposed as to prevent anything like free rotation, but as the capsules are lax and the facets do not fit closely to each other, a slight degree of rotatory motion does take place. Lateral flexion may take place in any part of the spine, but is most free in the cervical and lumbar regions. 2. ARTICULATION OF THE ATLAS WITH THE OCCIPITAL BONE. —The ligaments of this articulation are seven in number :— Two anterior occipito-atlantal, Two lateral occipito-atlantal, Posterior occipito-atlantal, Two capsular. Of the two anterior ligaments, one is a rounded cord, situated in the middle line, and attached above to the basilar process of the Fig. 151.—Anterior view of the ligaments connecting the atlas, axis, and occipital bone. A transverse section has been carried through the base of the skull, dividing the basilar process of the occipital bone and the petrous portion of the temporal bones. 1. Anterior round occipito-atlantal ligament. 2. Anterior broad occipito-atlantal liga- ment. 3. Commencement of the anterior common ligament. 4. Anterior atlanto- axial ligament, continuous interiorly with the commencement of the anterior common ligament. 5. One of the atlanto-axial cap- sular ligaments ; that on the opposite side has been removed to show the approxi- mated surfaces of the articular processes (6). 7. One of the occipito-atlantal capsular ligaments. The most external o these fibres constitute the lateral occipito-atlantal ligament. occipital bone; below, to the anterior tubercle of the atlas. The deeper ligament is a broad membranous layer, attached above to the margin of the occipital foramen, between the two condyles; and Fig. 152.—Posterior ligaments of the occi- pito-atlautul and atlanto-axial articula- tions. 1. Atlas. 2. Axis. 3. Posterior ligament of the occipito-atlantal articu- lation. 4, 4. Capsular and lateral liga- ments of this articulation. 5. Posterior ligament of the atlanto-axial articula- tion. 6,6. Its capsular ligaments. 7. The first pair of ligamenta subflava ; passing between the axis and third cervical vertebra. 8, 8. Capsular ligaments of those vertebrae. below, to the whole length of the anterior arch of the atlas ; it is continuous laterally with the capsular ligaments. The posterior ligament is thin and membranous ; attached above to the margin of the occipital foramen, between the two condyles; 186 LIGAMENTS OF THE AXIS AND OCCIPITAL BONE. and below, to the posterior arch of the atlas. It is closely adherent to the dura mater, by its inner surface ; and forms a ligamentous arch at each side for the passage of the vertebral artery and first cervical nerve. It corresponds in its position to the ligamenta sub- flava of the other vertebrae, but it has no elastic fibres, being com- posed entirely of white fibrous tissue. The two lateral ligaments are strong fasciculi of ligamentous fibres, attached below to the base of the transverse process of the atlas at each side ; and above, to the transverse process of the occipital bone. The capsular ligaments are thin and loose ligamentous capsules which surround the synovial membranes of the articulations between the condyles of the occipital bone and the superior articular pro- cesses of the atlas. The ligamentous fibres are most numerous on the anterior and external part of the articulation. The movements taking place between the cranium and atlas are those of flexion and extension, giving rise to the forward nodding of the head ; there is also a slight lateral movement to either side. When either of these actions is increased to any extent, the whole of the cervical region concurs in its production. 3. ARTICULATION OF THE AXIS WITH THE OCCIPITAL BONE. —The ligaments of this articulation are four in number :— Occipito-axial, Three odontoid. The occipito-axial ligament (apparatus ligamentosus colli) is a broad and strong band, which covers in the odontoid process and its ligaments. It is attached below to the body of the axis, where it Fig. 153.—Upper part of the vertebral canal, opened from behind in order to show the occipito-axial ligament. 1. Basilar portion of the sphenoid bone. 2. Section of the occipital bone. 3. Atlas, its posterior arch removed. 4. Axis, posterior arch removed. 5. Occi- pito-axial ligament, rendered promi- nent at its middle by the projection of the odontoid process. 6. Lateral and capsular ligament of the occipito- atlantal articulation. 7. Capsular liga- ment of the articular process of the atlas and axis. is continuous with the posterior common ligament; superiorly it is inserted by a broad expansion into the basilar groove of the occipital hone, where it is blended with the dura mater. The odontoid ligaments (alar or check ligaments) are two short and thick fasciculi, which pass outwards from the apex of the odontoid process to the sides of the occipital foramen and condyles. A third and smaller fasciculus (ligamentum dentis suspensorium) proceeds from the apex of the odontoid process to the anterior margin of the foramen magnum. These ligaments serve to limit the extent of rotation of the head ; hence they are termed check ligaments. 4. ARTICULATION OF THE ATLAS WITH THE AXIS.—-The liga- ments of this articulation are Jive in number :— LIGAMENTS OF THE ATLAS AND AXIS. 187 Anterior atlanto-axial, Posterior atlanto-axial, Two capsular, Transverse. The anterior ligament consists of ligamentous fibres which pass from the anterior tubercle and arch of the atlas to the base of tlie odontoid process and body of the axis, where they are continuous with the commencement of the anterior common ligament. The fibres in the middle form a thick band which is tense in all positions of the joints ; the lateral portions are thin, and assist in limiting the rotation of the atlas on the axis. The posterior ligament is a thin, membranous layer, passing between the posterior arch of the atlas and the laminae of the axis ; it represents the ligamenta subflava in a rudimentary state, and has on its deep or anterior surface a layer of dense elastic fibres, like those of the latter. The capsular ligaments surround the articular process of the atlas and axis ; they are loose, to permit of the free movement which exists between these vertebrae. The ligamentous fibres are most numerous on the outer and anterior part of the articulation ; and the synovial membrane of each joint often communicates with the synovial cavity between the transverse ligament and odontoid process. The transverse ligament is a strong ligamentous band, which arches across the area of the ring of the atlas from a rough tubercle Fig. 154.—Posterior view of the ligaments connecting the atlas, axis, and occipital bone. The posterior part of the occi- pital bone has been sawn away, and the arches of the atlas and axis removed. 1. Superior part of the occipito-axid ligament, which has been cut away in order to show the ligaments beneath. 2. Transverse ligament of the atlas. 3. 4. Ascending and descending slips of the transverse ligament, which have ob- tained for it the title of cruciform liga- ment. 5. One of the lateral odontoid ligaments: the fellow-ligament is seen on the opposite side. 6. One of the occipito- atlantal capsular ligaments. 7. One of the atlanto-axial capsular ligaments. on the inner surface of one articular process to a corresponding tubercle on the other ; and serves to retain the odontoid process of the axis in connection with the anterior arch of the atlas. As it crosses the neck of the odontoid process, some fibres are sent down- wards to be attached to the body of the axis, and others pass upwards to be inserted into the basilar process of the occipital bone ; hence the ligament has a cross-like appearance, and is termed cruciform. A synovial membrane is situated between the transverse ligament 188 and odontoid process ; and another between that process and the anterior arch of the atlas. Actions.—It is the peculiar disposition of the transverse ligament in relation to the odontoid process that enables the atlas, and with it the entire cranium, to rotate upon the axis ; the perfect freedom of movement between these bones being ensured by the two synovial membranes. The lower part of the ring, formed by the transverse ligament with the atlas, is smaller than the upper, while the summit of the odontoid process is larger than its base ; hence the process is retained in its place by the transverse ligament when the other liga- ments are cut through. The extent to which rotation of the head upon the axis can be carried, is determined by the odontoid or check ligaments. The odontoid process with its ligaments is covered in by the oecipito-axial ligament. ‘5. TEMPORO-MAXILLARY ARTICULATION.—The ligaments of this joint are the following :— TEMPORO-MAXILLARY ARTICULATION r between that process and the External lateral, Two internal lateral, Capsular, Interarticular libro-cartilage, Stylo-maxillary ligament, Two synovial membranes. The external lateral ligament is a short and thick hand of ill ires, passing obliquely backwards from the tubercle of the zygoma, lo the external surface of the neck of the lower jaw. It is incorporated with the capsular ligament, and is, in relation, ex- ternally, with the integument of the face; internally, with the two synovial membranes of the articulation and the interarticular cartilage. The short internal lateral ligament has a broad attachment above to the outer part of the spine of the sphenoid, and is in- serted below into the ridge on the inner side of the neck of the con- dyle. It is intimately connected with the capsule, and is separated from the long internal lateral liga- ment by fat and areolar tissue. The long internal lateral ligament (s'pheno-maxillarv) is a thin aponeurotic expansion extending from the extremity of the spinous process of the sphenoid bone to the margin of the dental foramen ; it is pierced at its insertion by the mylo-liyoidean nerve. Between the internal lateral ligament and neck of the jaw is a triangular space, in which are situated the internal maxillary artery, auriculo-temporal nerve, inferior dental artery and nerve, and part Fig. 155.—External view of the articul 1- tion of the lower jaw. 1. Zygomatic arch. 2. Tubercle of the zygoma. 3. Ramus of the lower jaw. 4. Mastoid portion of the temporal bone. 5. Ex- ternal lateral ligament. 6. Stylo-inaxil- lary ligament. TEMPORO-M AXILLARY ARTICULATION. of the external pterygoid muscle ; internally the ligament is in relation with the internal pterygoid muscle. The middle meningeal artery in its upward course to the foramen Fig. 156.—Internal view of the articulation of the lower jaw. 1. Section through the petrous portion of the temporal bone and spinous process of the sphenoid. 2. Internal surface of the ramus and body of the lower jaw. 3. Capsular ligament. 4. I.ong in- ternal lateral ligament. 5. A small interval at its insertion through which the mylo- hyoidean nerve passes. 6. Stylo-maxillary ligament, a process of the deep cervical fascia. spinosum, and the inferior dental nerve as it passes downwards to t lie dental canal, run along the outer side of this ligament. The capsular ligament consists of numerous irregular ligament- ous fibres, which pass from the edge of the glenoid cavity to the neck of the lower jaw, and surround the articulation. The capsule is thickest where it receives the acces- sory fibres called external and short internal lateral ligaments; it has inserted into it anteriorly a few fibres of the external pterygoid muscle. The interarticular fibro-carti- lage is a thin oval plate, thicker at the edges than in the centre, placed horizontally between the head of the condyle of the lower jaw and the glenoid cavity. Its upper surface is, from before back- wards, concave anteriorly and slightly convex posteriorly, the former por- tion fitting the eminentia articularis, and the latter the glenoid cavity ; its under surface is concave to receive the convex condyle. It is connected by its outer border with the external lateral ligament, and receives in front some fibres of insertion of the external pterygoid muscle. It divides the joint into two cavities, one being above, the other below, the cartilage ; hut it is occasionally incomplete in the centre. T1 ie synovial membranes are situated, one above, the other below the fibro-cartilage, the former being the larger of the two. When the fibro-cartilage is perforated, the synovial membranes communicate. Besides the lower jaw, there are several other joints provided Fig. 157.—In ttiis sketch a section has been made through the joint to show tlie position of the interarticular fibr''-cartilage, and the manner of its adaptation to the articulating surfaces. 1. Glenoid fossa. 2. Em- inentia articularis. 3. Interaiticu- lar fibro-cartilage. 4. Superior syno- vial cavity. 5. Inferior synovial cavity. 6. An interarticular fibro- cartiiage, removed from the joint, in order to show its oval and concave form ; it is seen from below. LIGAMENTS OF THE RIBS. 190 with a complete interarticular cartilage, and, consequently, with two synovial membranes ; they are—the sterno-clavicular, acromio- clavicular, and the articulation of the ulna with the cuneiform bone. The interarticular fibro-cartilages of the knee-joint are partial, and there is but one synovial membrane. The articulations of the heads of the ribs with the vertebra; have two synovial membranes separated by an interarticular ligament without fibro-cartilage. Connected with the lower jaw, though not with the joint, is the stylo-maxillary ligament, a process of the deep cervical fascia extended between the point of the styloid process and the angle of the jaw. It is attached to the jaw between the insertions of the masseter and internal pterygoid muscle ; it separates the parotid from the submaxillary gland, and gives attachment to some fibres of the stylo-glossus muscle. Actions.—The movements of the lower jaw are—depression, by which the mouth is opened ; elevation, by which it is closed ; a for- ward and backward movement ; and a movement from side to side. In the movement of depression the interarticular cartilage glides for- ward on the eminentia articularis, carrying with it the condyle. I11 elevation the fibro-cartilage and condyle are returned to their original position, ’['he forward and backward movement is a gliding of the fibro-cartilage on the eminentia articularis in the antero-posterior direction ; and the movement from side to side, in the lateral direc- tion. The articulation between the condyle and fibro-cartilage forms a true ginglymus or hinge-joint, that between the fibro-cartilage and eminentia articularis an arthrodial or gliding joint. The arteries of the temporo-maxillary joint are derived from the posterior auricular, anterior tympanic of internal maxillary, inferior or ascending palatine of facial, temporal, and middle meningeal. The nerves are chiefiy derived from the auriculo-temporal, but some filaments also come from the masseteric branch of inferior maxillary. 6. ARTICULATION OF THE RIBS WITH THE VERTEBRA.— The ligaments of these articulations are remarkable for their strength, being in fact so strong as to render dislocation impossible ; the neck of the rib must break before displacement could occur ; they are divisible into two groups :—(1) Those connecting the head of the rib with the bodies of the vertebrae ; and (2) Those connecting the neck and tubercle of the rib with the transverse processes. 1st Group. Anterior costo-vertebral or stellate, Capsular, T nterarticular ligament, Two synovial membranes. 2nd Group. Anterior costo-transverse, Middle costo-transverse, Posterior costo-transverse. The anterior costo-vertebral or stellate ligament (costo- central, Fig. 147) consists of three short bands of ligamentous fibres which radiate from the anterior part of the head of the rib. The superior band passes upwards to be attached to the vertebra above ; LIGAMENTS OF THE RIBS. 191 the middle fasciculus is attached to the intervertebral substance ; the inferior to the vertebra below. In the first rib the ligament is not divided, but its fibres pass to the body of the last cervical as well as the first dorsal. In like manner the ligaments connected with the tenth, eleventh, and twelfth ribs pass to the body of the ver- tebra above, as well as to that with which the head of the rib articulates. The capsular liga- ment is a thin layer of ligamentous fibres surrounding the joint in the interval left by the anterior ligament; it is thickest above and below the articula- tion, and protects the synovial membranes. The interarticular ligament is a short band of fibres which passes between the sharp crest on the head of the rib and the inter- vertebral substance. It divides the joint into two cavities, each being furnished with a separate synovial membrane. The first, tenth, eleventh, and twelfth ribs have no interarticular ligament, and consequently but one synovial membrane. The anterior (or superior) costo-transverse ligament is a broad band composed of two fas- ciculi, which ascend from the crest- like ridge on the neck of the rib, to the transverse process immedi- ately above. The ligament sepa- rates the anterior from the dorsal branch of the intercostal nerve ; it is absent from the first rib. The middle costo-transverse ligament is a strong interosseous ligament passing directly between the posterior surface of the neck of the rib, and the anterior surface of the transverse process against which it rests. It is rudimentary in the two inferior ribs. Fig. 158.—Transverse section of dorsal vertebra and beads of ribs. 1. Head of rib. 2. Transverse process of vertebra. 3. Anterior costo-vertebral or stellate ligament. 4. Interosseous costo-transverse ligament. 3. Posterior costo-transverse ligament. Fro. 159.—Posterior view of part of the dorsal portion of the vertebral column, showing the ligaments connecting the vertebrae with each other and the ribs with the vertebrae. 1, 1. Supraspin- ous ligament. 2, 2, 2. Ligamenta subflava, connecting the laminae. 3. Anterior costo-transverse ligament. 4. Posterior costo-transverse liga- ments. ARTICULATIONS OF THE COSTAL CARTILAGES. 192 The posterior costo-transverse ligament is a small but strong fasciculus, passing obliquely from the tubercle of the rib to the apex of the transverse process. The articulation between the tubercle of the rib and the transverse process is provided with a small synovial membrane. This ligament is absent in the two last ribs. Several accessory bands are found passing between the transverse processes and the ribs ; a broad band of this kind connects the last rib with the transverse process of the first or second lumbar vertebra. Actions.—The movements permitted by the articulations of the ribs are upwards, doumwards, and slightly forwards and backwards; the movement increasing in extent from the head to the extremity of the rib. The forward and backward movement is trifling in the seventh superior, but greater in the inferior ribs ; the eleventh and twelfth are very movable. 7. ARTICULATION OF THE COSTAL CARTILAGES WITH THE STERNUM, AND WITH EACH OTHER.—The ligaments of the chondro-sternal articulations are :— Anterior chondro-sternal, Posterior chondro-sternal. Superior chondro-sternal, Inferior chondro-sternal, The anterior chondro-sternal ligament (anterior stellate liga- ment) is a thin band of ligamentous fibres, passing in a radiated direction from the extremity of the costal cartilage to the anterior surface of the sternum, and intermingling its fibres with those of the ligament of the opposite side, and with the tendinous fibres of origin of the pectoralis major muscle. The posterior chondro-sternal ligament, much smaller than the anterior, consists of a thin fasciculus of fibres, situated on the posterior surface of the articulation. The superior and inferior chondro-sternal ligaments are narrow fasciculi corresponding with the breadth of the cartilage, and connecting its superior and inferior border with the side of the sternum. The synovial membrane is absent in tlie articulation of the first rib, its cartilage being usually adherent to the sternum ; that of the second rib lias an interarticular ligament, with two synovial mem- branes ; the synovial membranes of the other costal cartilages are single. Tl le sixth and seventh ribs have several fasciculi of strong liga- mentous fibres, passing from the extremity of their cartilages to the anterior surface of the ensiform cartilage, which latter they are intended to support. They are named the chondro-xyphoid liga- ments. Tl le sixth, seventh, and eighth, and sometimes the fifth and the ninth costal cartilages, have articulations with each other, and a synovial membrane for each articulation. They are connected by ligamentous fibres (ligamenta coiruscantia), which pass from one cartilage to the other. Sv novial membranes. Ligaments of the sternum. The ninth and tenth are connected at their extremity by liga- mentous fibres, but have no synovial membrane. Actions.—The movements of the chondro-sternal articulations are very trifling, being limited to a slight degree of gliding motion. The first rib is the least, the second the most movable. 8. ARTICULATIONS OF THE RIBS WITH THE COSTAL CARTI- LAGES.—The anterior extremity of each rib is excavated, so as to receive the convex outer end of the costal cartilage ; there is no true ligament, but the periosteum is prolonged on the cartilage, and takes the place of one. No motion takes place at this articulation. 9. ARTICULATIONS OF THE STERNUM. — The pieces of the sternum are connected by means of a thin plate of interosseous cartilage placed between each, and by an anterior and posterior ligament. The fibres of the anterior sternal ligament are longi- tudinal in direction, but so blended with the anterior chondro-sternal ligaments and tendinous fibres of origin of the pectoral muscles, as scarcely to be distinguished as a distinct ligament. The posterior sternal ligament is a broad smooth plane of' longitudinal fibres, placed on the posterior surface of the bone, and extending from the manubrium to the ensiform cartilage. These ligaments contribute very materially to the strength of the sternum and elasticity of the front of the chest; their continuation downwards on the ensiform cartilage constitutes the sterno-xyphoid ligaments. 10. ARTICULATION OF THE VERTEBRAL COLUMN WITH THE PELVIS.—The last lumbar vertebra is connected with the sacrum by the same ligaments as those with which the various vertebrae are connected to each other : viz., anterior and posterior common liga- ment, intervertebral substance, ligamenta subflava, capsular liga- ments, interspinous and supraspinous ligament. There are, however, tivo proper ligaments connecting the vertebral column with the pelvis ; these are the Sacro-lumbar, Ilio-lumbar. The sacro-lumbar or sacro-vertebral ligament is a thick triangular fasciculus of ligamentous fibres, connected above with the lower and front part of the transverse process of the last lumbar vertebra, and below with the upper border of the sacrum, becoming blended with the anterior sacro-iliac ligament. The ilio lumbar ligament passes from the apex of the transverse process of the last lumbar vertebra to that part of the crest of the ilium which surmounts the sacro-iliac articulation. It is triangular in form, and gives origin to the quadratus lumborum and a few fibres of the iliacus muscle. n. ARTICULATIONS OF THE PELVIS.—The ligaments of the articulations of the pelvis are divisible into four groups :—(1) Those connecting the sacrum and ilium; (2) those passing between the sacrum and ischium; (3) between the sacrum and coccyx; and (4) between the two pubic bones. LIGAMENTS OF THE PELVIS. " 194 1st, Between the sacrum and ilium. Anterior sacro-iliac, Posterior sacro-iliac. 2nd, Between the sacrum and ischium. Lesser sacro-iscbiatic, Greater sacro-ischiatic. 3rd, Between the sacrum and coccyx. Anterior sacro-coccygean, Posterior sacro-coccygean. 4th, Between the -pubic bones. Anterior pubic, Posterior pubic, Superior pubic, Sub-pubic, Interosseous fibro-cartilage. i. Between the Sacrum and Ilium.—This joint is commonly known as the sacro-iliac synchondrosis, but is sometimes called the sacro-iliac symphysis ; it belongs to the class amphi-arthrosis. The anterior sacro-iliac ligament consists of numerous short ligamentous bands and fibres, which pass from bone to bone on the anterior surface of the joint. The posterior sacro-iliac or interosseous ligament is composed of numerous strong fasciculi of ligamentous fibres, which pass horizontally be- tween the rough surfaces of the posterior half of the sacro-iliac articulation, and constitute the principal bond of connection between the sacrum and ilium. They are lodged in the hollow between the posterior surface of the sacrum and the back- ward projection of the ilium. One fasciculus of this ligament, longer and larger than the rest, is distinguished, from its direc- tion, by the name of oblique sacro-iliac ligament. It is attached, by one extremity, to the pos- terior superior spine of the ilium ; and, by the other, to the third transverse tubercle on the posterior surface of the sacrum. The surfaces of the two bones forming the sacro-iliac articulation are partly connected by cartilage, and partly rough and connected by the interosseous ligament. The anterior or auricular half is Fio. 160.—Ligaments of the pelvis and hip- joint. x. Lower part of the anterior com- mon ligament of the vertebrae, extending downwards over the front of the sacrum. 2. Sacro-lumbar ligament. 3. Uio-lumbar ligament. 4. Anterior sacro-iliac ligament. 5. Obturator membrane. 6. Poupart’s liga- ment. 7. Gimbernat’s ligament. 8. Cap- sular ligament of the hip-joint. 9. Ilio- femoral or accessory ligament. LIGAMENTS OF THE PELVIS. 195 coated by a layer of cartilage which binds the corresponding surfaces of the ilium and sacrum together ; when the two bones are forcibly separated this cartilage sometimes adheres to the ilium, sometimes to the sacrum, and occasionally splits equally or unequally. In some instances there are two plates of cartilage with a small cavity be- tween them, and this arrangement is more common in the female than in the male. 2. Between the Sacrum and Ischium. — The anterior or lesser sacro-ischiatic ligament is thin and triangular in form; it is attached by its apex to the spine of the ischium, and by its broad extremity to the side of the sacrum and coccyx, interlacing its fibres with the greater sacro-ischiatic ligament. By its upper border it forms part of the lower boundary of the great sacro- ischiatic foramen, and by the lower, part of the lesser sacro-ischiatic foramen. The posterior or greater sacro-ischiatic ligament, larger, thicker, and posterior to the preceding, is narrower in the middle Fig. 161.—Ligaments of the pelvis and hip-joint, late- ral view. i. Oblique sacro- iliac ligament. The other fasciculi of the posterior sacro-iliac ligament are not seen in this view of the pelvis. 2. Greater sacro - ischiatic ligament. 3. Lesser sacro-ischiatic ligament. 4. Great sacro- ischiatic foramen. 5. Lesser sacro-ischiatic fora- men. 6. Cotyloid ligament of the acetabulum. 7. Ligamentum teres. 8. Cut edge of the capsular liga- ment, showing its extent posteriorly, as compared with its anterior attach- ment. 9. Obturator mem- brane, only partly seen. than at each extremity. It is attached, by its smaller end, to the inner margin of the tuberosity and ramus of the ischium, where it forms a falciform process, which protects the internal pudic artery, and is continuous with the obturator fascia. By its larger extremity it is inserted into the side of the coccyx, sacrum, posterior inferior spine, and extremity of the crest of the ilium. The greater sacro-ischiatic ligament is in relation, in front, with the lesser ligament; behind, with the gluteus maximus, to some fibres of which it gives origin. By its superior border it forms part of the boundary of the lesser ischiatic foramen, and, by its lower border, part of the boundary of the perinseum. It is pierced by the 196 LIGAMENTS OF THE PELVIS. coccygeal branch of the ischiatic artery. The two ligaments convert the sacro-ischiatic notches into foramina. 3. Between the Sacrum and Coccyx.—The anterior sacro- coccygean ligament is a thin fasciculus passing from the anterior surface of the sacrum to the front of the coccyx, and is continuous with the anterior common ligament. The posterior sacro-coccygean ligament is a thick ligamentous layer, which completes the lower part of the sacral canal, and con- nects the sacrum with the coccyx posteriorly, extending as far as the apex of the latter bone. It is a direct continuation of the posterior common ligament, and becomes connected with the termination of Fig. 162.—Ligaments of pelvis and hip-joint. 1. Posterior sacro-iliae ligament. 2. Great sacro-sciatic ligament. 3. Oblique sacro-iliac ligament. 4. Lesser sacro- sciatic ligament. 5. The same, exposed by the removal of the greater. 6. Back part of capsule of hip-joint. 7. Posterior sacro-coccygeal ligament. the supraspinous ligament, and the filum terminate of the spinal cord. Between the two bones is a thin intervertebral disc of fibro- cartilage; and in females not unfrequently a synovial membrane. The articulation admits of a certain degree of movement backwards during parturition. The ligaments connecting the different pieces of the coccyx con- sist of a few scattered anterior and posterior fibres, and a thin disc of interosseous cartilage ; the latter exists only in the young subject, as, in the adult, the pieces become ossified. 4. Between the Pubic Bones.—This articulation receives the name of symphysis pubis; it is an example of an amphi-artlirodial joint. The anterior pubic ligament is composed of ligamentous fibres, LIGAMENTS OF THE UPPER EXTREMITY. 197 which pass obliquely across the union of the two bones from side to side, and form an interlacement in front of the symphysis. The posterior pubic ligament consists of a few irregular bands of fibres uniting the pubic bones posteriorly. The superior pubic ligament is a thick band of fibres connecting the angles of the pubes superiorly, and filling the inequalities of the surface of the bones. The sub-pubic ligament is a thick arch of fibres connecting the two bones interiorly, and forming the upper boundary of the pubic arch. The interosseous fibro-cartilage unites the two surfaces of the pubic bones in the same manner as the intervertebral substance con- nects the bodies of the vertebrae. It resembles the intervertebral substance also in being composed of oblique fibres disposed in con- centric layers, which are more dense towards the surface than near the centre. It is thick in front, and thin behind ; and a synovial membrane is found in the upper and posterior part of the articulation. This articulation becomes movable towards the latter term of pregnancy, and admits of a slight degree of separation of its sur- faces. The obturator membrane is not a ligament of articulation, but simply a ligamentous membrane stretched across the obturator fora- men. It gives attachment by its surfaces to the two obturator muscles, and leaves a space in the upper part of the foramen for the passage of the obturator vessels and nerve. LIGAMENTS OF THE UPPER EXTREMITY. The ligaments of the upper extremity may be arranged in the order of the articulations of the different bones ; they are :— 1. Sterno-clavicular articula- tion. 2. Scapulo-clavicular articula- tion. 3. Ligaments of the scapula. 4V Shoulder-joint. 5. Elbow-joint. 6. Radio-ulnar articulations. 7. Wrist-joint. 8. Articulation between the carpal bones. 9. Carpo-metacarpal articula- tions. 10. Metacarpo - phalangeal arti- culations. 11. Articulations of the pha- langes. i. STERNO-CLAVICULAR ARTICULATION.—The sterno-clavicu- lar is an arthrodial articulation ; its ligaments are :— Anterior sterno-clavicular, Inter-clavicular, Posterior sterno-clavicular, Costo-clavicular (rhomboid), Interarticular fibro-cartilage, Two synovial membranes. The anterior sterno-clavicular ligament is a broad ligamen- 198 STERNO-CLAVICULAR ARTICULATION. tous layer extending obliquely downwards and inwards, and cover- ing the anterior aspect of the articulation. This ligament is in relation by its anterior surface with the integument and sternal origin of the sterno-mastoid muscle ; and behind with the inter- articular fibro-cartilage and synovial membranes. The posterior sterno-clavicular ligament is a broad band covering the posterior surface of the articulation. It is in relation Fig. 163.—Ligaments of the ster- no-clavicular and chondro-sternal articulations. 1. Anterior sterno- clavicular ligament. 2. Inter- clavicular ligament. 3. Costo- clavicular or rhomboid ligament, seen on both sides. 4. Inter- articular fibro-cartilage, brought into view by the removal of the anterior and posterior ligaments. 5. Anterior chondro-sternal liga- ments of the first and second ribs. by its anterior surface with the interarticular fibro-cartilage and synovial membranes ; and behind, with the sterno-hyoid and sterno- thyroid muscle. The anterior and posterior sterno-clavicular ligaments, together with a few short fibres connecting the bones above, are sometimes described as forming one ligament, which is then called capsular. The inter-clavicular ligament is a cord-like band which crosses from the extremity of one clavicle to that of the other, and is closely adherent to the upper border of the sternum. The costo-clavicular or rhomboid ligament is a thick fasciculus of fibres, connecting the sternal extremity of the clavicle with the cartilage of the first rib. It is placed obliquely between the rib and under surface of the clavicle ; and is in relation, in front, with the tendon of origin of the subclavius muscle, and behind with the subclavian vein. The interarticular fibro-cartilage is nearly circular in form, and thicker at the edges than in the centre. It is attached above, to the clavicle ; below, to the cartilage of the first rib ; and through- out the rest of its circumference, to the anterior and posterior sterno- clavicular ligaments. It divides the joint into two cavities, which are lined by separate synovial membranes; is sometimes pierced through its centre, and not unfrequently deficient, to a greater or less extent, at its lower part. One of the synovial cavities lies between the end of the clavicle and interarticular cartilage, the other between the sternum and the cartilage ; the former is more loose than the latter. Actions.—The movements of the sterno-clavicular articulation are—a gliding movement of the clavicle on the fibro-cartilage, or of the latter on the sternum, in the directions forward, backward, upward, and downward; and circumduction. The upward and downward movements take place between the clavicle and inter- SCAPULO-CLAVICULAR ARTICULATION. 199 articular cartilage, the forward and backward movements between the cartilage and the sternum ; in circumduction the two portions of the articulation alternately take part in the movement. The upward movement is limited by the rhomboid ligament, the down- ward movement by the inter-clavicular ligament. This articulation is the centre of the movements of the shoulder. 2. SCAPULO-CLAVICULAR ARTICULATION.—The ligaments of the scapular end of the clavicle are :— Superior acromio-clavicular, Inferior acromio-clavicular, Coraco-clavicular (trapezoid and conoid), Interarticular fibro-cartilage, Two synovial membranes. The superior acromio-clavicular ligament is a moderately thick plane of fibres passing be- tween the extremity of the clavicle and the acromion, on the upper surface of the joint. It is strengthened by the tendinous fibres of the trapezius and deltoid, and on its deep surface is connected with the inter- articular cartilage. The inferior acromio- clavicular ligament is a thin plane situated on the under surface. These two ligaments are continuous with each other in front and behind, and form a capsule around the articu- lation. The interarticular fibro-cartilage is often indistinct, from having partial connections with the cartilaginous surfaces of the two bones between which it is placed, and is frequently absent. When partial, it occupies the upper part of the articula- tion. The synovial mem- branes are thin ; and when the fibro-cartilage is in- complete, there is but one. The coraco-clavicular ligament is a thick fasciculus of ligamen- Fig. 164.—Ligaments of the scapula and shoulder- joint. x. Superior acromio-clavicular ligament. 2. Coraco-elavicular ligament; this aspect of the ligament is named trapezoid. 3. Trapezoid por- tion of the same ligament. 4. Coraco-acromial ligament. 5. Transverse ligament. 6. Capsular ligament. 7. Coraco-humeral ligament. 8. The long tendon of the biceps issuing from the capsular ligament, and entering the bicipital groove. 200 LIGAMENTS OF THE SCAPULA. tous fibres, passing obliquely between the base of the coracoid process and the under surface of the clavicle, and holding the end of the clavicle in firm connection with the scapula. It is divisible into two parts, an anterior and external called trapezoid, and a posterior and internal called conoid. The trapezoid portion is seen best from the front; it is attached below to the upper surface of the coracoid process and above to the oblique line on the under surface of the clavicle ; its anterior border is free, its posterior joins with the conoid portion. The conoid ligament has its base directed upwards and attached to the conoid tubercle on the under surface of the clavicle ; its apex is inserted into a rough process at the base of the coracoid process of the scapula. Actions.—The acromio-clavicular articulation admits of two movements, gliding of the surfaces on each other, and rotation of the scapula on the extremity of the clavicle, the extent of this rotation being limited by the two parts of the coraco-clavicular ligament. Bursae.—There are commonly three bursae in connection with this articulation ; one in the recess between the trapezoid and conoid ligaments, one between the base of the coracoid process and apex of the conoid ligament, and the third between the coraco-acromial liga- ment and the capsule of the shoulder-joint. 3. The PROPER LIGAMENTS OF THE SCAPULA are Coraco-acromial, Transverse. The coraco-acromial ligament is a broad and thick triangular band, which forms a protecting arch over the shoulder-joint. It is attached by its apex to the point of the acromion process, and by its base to the external border of the coracoid process its whole length. This ligament is in relation above with the clavicle and under surface of the deltoid muscle ; and below with the tendon of the supra-spinatus muscle, a bursa mucosa being usually interposed. The transverse or coracoid ligament (supra-scapular) is a narrow but strong fasciculus which crosses the notch in the upper border of the scapula, from the base of the coracoid process, and converts it into a foramen. The supra-scapular nerve passes through this foramen, the artery and veins over it. The omo-hyoid muscle takes origin from this iigament. Movements of the Scapula.—The mobility of the scapula is very great; it takes place in upward, downward, forward, and backward directions, and by a combination of all these as a modified circumduction. In the forward and backward movements the scapula glides over the chest wall, carrying the clavicle with it, and being kept in apposition with the chest by the latissimus dorsi muscle. In raising the arm at the shoulder, the deltoid and supra- spinatus can only raise it to a right angle with the trunk ; elevation above that is effected by the rotation of the scapula on the chest wall by the trapezius, the glenoid cavity being directed upwards and forwards. The rotation movement commences at the very beginning SHOULDER-JOINT. 201 of lifting the arm, and not (as was formerly supposed) when the arm has leached the level of the shoulder. 4. SHOULDER-JOINT.—The scapulo-humeral articulation is an enarthrosis, or ball-and-socket joint; its ligaments are :— Capsular, Coraco-humeral, Gleno-humeral. Glenoid, The capsular ligament encloses the articulating head of the scapula and head of the humerus, and is attached above to the neck of the scapula externally to the glenoid ligament, and to the root of the coracoid process ; on the humerus it is attached to the upper half of the anatomical neck, but below it passes farther from the articular surface, some of its deeper fibres being, however, reflected upwards to terminate at the articular margin, much in the same way as fibres are reflected on the neck of the femur in the hip. It is thick above, where resistance is most required, and strengthened by the tendons of the supra-spinatus, infra-spinatus, teres minor, and subscapularis muscles : below it is thin and loose. The tendons of all the muscles in contact with the capsule except the subscapu- laris can be readily separated from it by careful dissection, but the latter either has beneath it a bursa which communicates with the cavity of the joint, or is itself united with the capsule and lined by the synovial membrane of the articulation. The coraco-humeral ligament is a broad band which descends obliquely outwards from the border of the coracoid process to the greater tuberosity of the hume- rus, and serves to strengthen the superior and anterior part of the capsular ligament; it assists the latter in bridging over the bicipital groove. The gleno-humeral ligament (ligament of Flood) is an acces- sory slip of fibres which projects into the joint along the inner edge of the biceps tendon, and is inserted into the upper part of the bicipital groove. It is supposed to be the homologue of the ligamentum teres in the hip-joint. The glenoid ligament is the prismoid band of fibro-cartilage, which is attached around the margin of the glenoid surface for the purpose of protecting its edge and deepening its cavity. It divides superiorly into two slips which are continuous with the long tendon of the biceps ; Fig. 165.—Section through the shoulder- joint. 1. The cut end of the clavicle. 2. Acromial end of the clavicle. 3. Arti- cular surface of the glenoid cavity covered with cartilage. 4. Cross section of the glenoid ligament. 5. Lower part of cap- sule and synovial sac. 6. Synovial mem- brane prolonged on biceps tendon. 7. Tendon of biceps muscle. 202 SHOULDER-JOINT. hence the ligament is sometimes described as being formed by the splitting of that tendon. The cavity of the articulation is traversed by the long tendon of the biceps, which is enclosed in a sheath of synovial membrane in its passage through the joint. The synovial membrane of the shoulder-joint is extensive ; it communicates anteriorly through an opening in the capsular ligament with a large bursal sac, which lines the under surface of the tendon of the subscapularis muscle. Superiorly it frequently communicates through another opening in the capsular ligament with a bursal sac belonging to the infra-spinatus muscle ; and it moreover forms a sheath around that portion of the tendon of the biceps which is included within the joint. Capsular Muscles.—The muscles immediately surrounding the shoulder-joint are—the subscapularis, supra-spinatus, infra-spinatus, teres minor, long head of the triceps, and deltoid; the long tendon of the biceps is within the capsular ligament. Actions.—The shoulder-joint is capable of every variety of motion—viz., of movement forwards and backwards, of abduction and adduction, of circumduction and rotation. The great freedom of movement which this joint enjoys depends on the laxity of the capsule and the large size of the head of the humerus in comparison with the depth of the glenoid cavity. The capsule is so loose that if an opening be made in it the humerus will fall about an inch from the scapula, showing that the articular surfaces are not kept in con- tact by the fibres of the capsule, but by atmospheric pressure. Bursae.—The bursae in connection with this joint are four in number: one between the subscapularis tendon and the capsule and neck of the scapula ; a second one between the capsule and the tendon nearer to the insertion of the latter; a third between the tip of the coracoid process and the capsule ; and a fourth between the combined origins of the biceps and coraco-brachialis and the capsule. Nerve-supply.—Branches of the circumflex and supra-scapular nerves. 5. ELBOW JOINT.—The elbow is a ginglymus or hinge-joint; and its ligaments four in number, namely :— Anterior, Posterior, Internal lateral, External lateral. The anterior ligament is a broad and thin membranous layer, descending from the anterior surface of the humerus immediately above the coronoid and radial fossae to the coronoid process of the ulna and orbicular ligament. It is connected on each side with the lateral ligaments, and is composed of fibres which pass in three different directions, vertical, transverse, and oblique, the latter being extended downwards and outwards to the orbicular ligament, into which they are inserted interiorly. This ligament is covered in by the brachialis anticus muscle. The posterior ligament is a broad and loose layer passing trans- versely across the olecranon fossa, and from the sides of the fossa to the base of the olecranon ; it is connected at each side with the lateral ligaments. It is covered in by the tendon of the triceps. The internal lateral ligament is a thick triangular layer, attached above, by its apex, to the internal condyle of the humerus ; and below, by its expanded border, to the margin of the greater sigmoid cavity of the ulna, extending from the coronoid process to the olecranon. At its insertion it is intermingled with some trans- verse fibres; and posteriorly is in relation with the ulnar nerve. The external lateral ligament is a strong and narrow band which descends from the ex- ternal condyle of the humerus, to be inserted into the orbicular ligament and the ridge on the ulna with which the posterior part of the latter ligament is connected. The ligament is closely united with the tendon of origin of the supinator brevis muscle. The four pre- ceding ligaments are sometimes described as one under the name of capsular liga- ment. The synovial membrane is ex- tensive, and is re- flected from the margins of the cartilaginous sur- faces of the bones upon the inner surface of the ligaments. It forms an articulating sac between the head of the radius and the lesser sigmoid notch of the ulna. The muscles immediately sur- rounding and in contact with the elbow-joint are—in front, brachialis anticus ; inner side, pronator radii teres, flexor sublimis digitorum, and flexor carpi ulnaris ; externally, extensor carpi radialis brevior, extensor communis digitorum, ex- ELBOW-JOINT. 203 Fig. 167.—Exter- nal view of the elbow-joint. 1. Humerus. 2. Ulna. 3. Radius. 4. External lat- eral ligament inserted inte- riorly into (5) the orbicular ligament. 6. Posterior ex- tremity of the orbicular liga- ment, spread- ing out at its insertion into the ulna. 7. Anterior liga- ment, scarcely apparent in this view of the ar- ticulation. 8. Posterior liga- ment, thrown into folds by the extension of the joint. Fig. 166.—Ligaments of the elbow-joint, inner side. i. An- terior ligament. 2. Internal lateral liga- ment. 3. Orbicular ligament. 4. Ob- lique ligament. 5. Interosseous mem- brane. 6. Internal epicondyle of the humerus, which con- ceals the posterior ligament. 204 RADIO-ULNAR ARTICULATION. tensor carpi ulnaris, anconeus, and supinator brevis ; behind, triceps and anconeus. Nerves.—The chief supply of the joint is derived from the ulnar nerve, but it also receives twigs from the muscular-cutaneous and median. Actions.—The movements of the elbow-joint are flexion and extension. These movements are oblique, so that the forearm is inclined inwards in flexion and outwards in extension. Flexion is limited by the meeting of the soft parts of the arm and forearm, and extension by the muscles and ligaments on the front of the joint becoming tense ; these effects being produced before the coro- noid and olecranon processes reach the bottom of their respective fossae. Bursae.—The bursae in connection with this joint are only three in number : the first of these lies between the tendons of the ex- tensor carpi radialis brevior and extensor communis digitorum, and the external lateral ligament; the second between the olecranon and posterior ligament; and the third between the olecranon and the superficial structures. 6. RADIO ULNAR ARTICULATION.—The radius and ulna are firmly held together by ligaments, connected with both extremities of the bones, and with the shaft; they are :— Orbicular, Oblique, Interosseous, Anterior inferior radio-ulnar. Posterior inferior radio-ulnar. Interarticular fibro-cartilage. The orbicular ligament (annular, coronary) is a firm band, several lines in breadth, which surrounds the head of the radius, and is attached by each end to an extremity of the lesser sigmoid cavity. Some of the lower fibres are continued round beneath the sigmoid cavity so as to form a complete circle. It is strongest behind where it receives the external lateral ligament, and is lined on its inner surface by a reflection of the synovial membrane of the elbow- joint ; it gives attachment to fibres of the supinator brevis muscle. The oblique ligament is a narrow slip of ligamentous fibres, descending obliquely from the base of the coronoid process of the ulna to the inner side of the radius, a little below its tuberosity. Its fibres run in the opposite direction to .those of the interosseous membrane. The interosseous membrane is a broad and thin plane of apo- neurotic fibres passing obliquely downwards from the sharp ridge on the radius to that on the ulna. It is deficient superiorly, broader in the middle than at each extremity, and perforated at its lower part for the passage of the anterior interosseous artery. The pos- terior interosseous artery passes backwards between the oblique ligament and upper border of the interosseous membrane. The interosseous membrane affords an extensive surface for the attachment of muscles ; and is in relation, in front, with the flexor profundus digitorum, flexor longus pollicis, pronator quadratus, and RADIO-ULNAR ARTICULATION. 205 anterior interosseous artery and nerve ; behind, with the supinator brevis, extensor ossis metacarpi pollicis, extensor primi internodii pollicis, extensor secundi internodii pollicis, extensor indicis, and near the wrist with the anterior interosseous artery and posterior in- terosseous nerve. The anterior inferior radio-ulnar ligament is a thin band of fibres, passing transversely between the anterior surface of the lower end of the radius and ulna. The posterior inferior radio-ulnar liga- ment, also thin and loose, has the same dis- position on the posterior surface of the articu- lation. The triangular interarticular fibro-carti- lage acts the part of a ligament between the lower extremity of the radius and ulna. It is inserted by its apex into a depression on the inner surface of the styloid process of the ulna, and attached by its base to the edge of the radius. This fibro-cartilage is lined oil the upper surface by a synovial membrane, which forms a remarkably loose capsule between the radius and ulna, and is called the membrana sacaformis. By its lower surface it enters into the articulation of the wrist-joint. Actions.—The movements taking place between the radius and ulna are—rotation of the former upon the latter, rotation forwards being termed pronation, and rotation backwards supination; in the former the palm of the hand comes to be directed downwards, in the latter it looks upwards. In these movements the head of the radius turns upon its axis, within its orbicular ligament and lesser sigmoid notch of the ulna ; while inferiorly, the radius presents a concavity whicii moves on the rounded head of the ulna. The ulna also moves, although in much less degree, in a direction opposite to that of the radius; this movement depends chiefly on rota- tion at the shoulder-joint, and to some extent on a laxity of the elbow-joint. The movements of the radius are chiefly limited by the anterior and posterior inferior ligaments ; hence these are not unfrequently ruptured in great muscular efforts. 7. WRIST-JOINT.—The wrist is a condyloid articulation ; the articular surfaces entering into its formation being the radius and Fig. 168. — Upper part of ulna and orbicular ligament, i. Olecra- non. 2. Tip of coronoid process. 3. Orbicular ligament. Fig. 169.—Lower end of radius and ulna, with articular surfaces. 1. Radius. 2. Ulna. 3. Inter- articular fibro-cartilage. 4. Ar- ticular end of radius. 5. Mem- brana sacciformis. WRIST-JOINT. 206 triangular fibro-cartilage above, and the rounded surface of the scaphoid, semilunar, and cuneiform bones below ; its ligaments are four in number :—; Anterior, Posterior, Internal lateral, External lateral. The anterior ligament is a broad and membranous layer consist- ing of three fasciculi, which pass downwards and inwards between the anterior margin of the lower end of the radius and the scaphoid, semilunar, and cuneiform bones. It is pierced by numerous small openings for vessels, and has lying in front of it the tendons of the flexor profundus digito- rum and flexor longus pollicis. The posterior ligament, also thin and loose, passes down- wards and inwards between the posterior surface of the radius and the posterior surface of the scaphoid, semilunar, and cunei- form bones. The internal lateral liga- ment extends from the styloid process of the ulna to the cunei- form and pisiform bones. The external lateral liga- ment is attached by one ex- tremity to the styloid process of the radius, and by the other to the side of the scaphoid bone, some of its fibres being pro- longed to the trapezium and an- terior annular ligament. The radial artery rests on this liga- ment as it passes backwards to the first metacarpal space. Actions. — The movements of the wrist-joint are flexion, extension, adduction, abduction, and circumduction: no rotation takes place at this joint. Nerve-supply.—The ulnar and posterior interosseous. Bursae.—The bursae in connection with this joint chiefly take the form of synovial sheaths for the tendons ; those more immediately in relation with the ligaments are as follows :—One between the tendon of. the flexor longus pollicis and the anterior ligament, one between the flexor profundus tendons and the same ligament, a third of rounded form between the tendon of the flexor carpi ulnaris Fi<;. 170.—1. Radius. 2. Interosseous mem- brane. 3. Articulation between lower end of ulna and interarticular fibro-cartilage opened. 4. Space for anterior interosseous artery. 5. External lateral ligament of wrist. 6. Lower end of ulna. 7. Anterior ligament of wrist. 8. Internal lateral liga- ment of wrist. 9. Tubercle of scaphoid. 10. Pisiform bone. 11. Trapezium. 12. Hook of unciform bone. 13. Articulation between trapezium and first metacarpal. 14. Anterior ligament of carpus. 16. Intermetacarpal and carpo - metacarpal ligaments. WRIST-JOINT. and the internal lateral ligament, a fourth separating the radial extensors from the posterior ligaments, a fifth beneath the tendons of the common extensor, and a sixth beneath the tendon of the extensor carpi ulnaris. 8. ARTICULATIONS BETWEEN THE CARPAL BONES.—These are arthrodial joints, with the exception of the conjoined head of the os magnum and unciform, which is received into a cup formed by the scaphoid, semilunar, and cuneiform bone, and constitutes an enarthrosis. The ligaments are :— 207 Dorsal, Palmar, Interosseous fibro-cartilages, Annular. The dorsal ligaments are ligamentous bands that pass trans- versely and longitudinally from hone to hone on the dorsal surface of the carpus. The palmar ligaments are fasciculi of the same kind, hut stronger than the dorsal, having the like disposition on the palmar surface. The interosseous ligaments are fibro-cartilaginous lamellae situated between the adjoining bones in each range : in the upper range they close the upper part of the space between the scaphoid, semilunar, and cuneiform bones; in the lower range they are stronger than in the upper, and connect the os magnum on the one side to the unciform, on the other to the trapezoid, leaving intervals through which the synovial membrane is continued to the bases of the meta- carpal bones. The anterior annular ligament is a firm ligamentous band, which connects the bones of the two sides of the carpus. It is attached by one extremity to the trapezium and scaphoid, by the other to the unciform process of the unciform and base of the pisi- form bones, and forms an arch over the anterior surface of the carpus, beneath which the tendons of the long flexors and the median nerve pass into the palm of the hand. The posterior annular ligament is a flattened band of fibrous tissue about half an inch in breadth, passing across from the lower end and styloid process of the radius to the cuneiform, pisiform, and base of the fifth metacarpal. It assists the posterior ligament of the wrist-joint in binding the] hand to the forearm, and in carry- ing the hand with the radius in pronation. A more complete de- scription of this ligament and the preceding will be found in the section on the muscles and fasciae. The articulation of the pisiform bone with the cuneiform is provided with a separate synovial membrane, protected by fasciculi of ligamentous fibres, which form a kind of capsule around the joint, and are inserted into the cuneiform bone. This bone is also connected with the unciform and base of the metacarpal of the little finger by two strong fibrous bands. Synovial Cavities.—There are five synovial cavities between the articulations of the carpus :— The first is situated between the lower end of the ulna and the CARPO-METACARPAL ARTICULATIONS. interarticular tibro-cartilage ; it has been described above, and is called sacciform, on account of forming a sacculus between the ulna and radius. The second is situated between the lower surface of the radius and interarticular fibro-cartilage above, and the first range of bones of the carpus below. The third, the most extensive of the synovial cavities of the wrist, is situated between the two rows of carpal bones, and passes between the bones of the first and between those of the second range, also between the carpal extremities of the four metacarpal bones of the fingers. The fourth is the synovial cavity of the articulation of the meta- carpal bone of the thumb with the trapezium. The fifth is situated between the pisiform and cuneiform bones. Actions.—Very little movement exists between the bones in each range, but more is permitted between the two ranges. The most important movements are flexion and extension, but there is also a slight amount of lateral motion and of rotation in the medio-carpal articulation. The rotation takes place by the head of the os magnum and upper outer angle of the unciform moving in the socket formed by the three outer bones of the first row, together with some gliding backwards and forwards of the trapezium and trapezoid on the scaphoid. 9. CARPO-METACARPAL ARTICULATIONS.—The second row of bones of the carpus articulates with the metacarpal bones of the Fig. i71. —Diagram showing the disposition ot the chief synovial membranes :of the wrist-joint. 1. Sacciform membrane. 11. Second synovial cavity, hi. Third or large synovial cavity. iv. Synovial cavity between the trapezium and metacarpal bone of thumb. That of the pisiform bone is here omitted. 1. Radius. 2. Ulna. 3. Internal lateral liga- ment. 4. External lateral liga- ment. 5. Cuneiform bone. 6. Semilunar. 7. Scaphoid. 8. Un- ciform. 9. Os magnum. 10. 'Tra- pezoid. 11. Trapezium. 12. In- terarticular fibro-cartilage. 13. Metacarpal bone of thumb. 14. Metacarpal of little finger. In- terosseous metacarpal ligaments. Interosseous ligaments are also seen connecting the bones of each row of the carpus. four fingers by dorsal and palmar ligaments ; and tbe metacarpal bone of the thumb with the trapezium by a capsular ligament. There is also in the carpo-metacarpal articulation a thin interosseous band, which passes from the ulnar edge of the os magnum to the METACARPO-PHALANGEAL ARTICULATIONS. 209 base of tbe third and fourth metacarpal bones at their point of connection. The dorsal ligaments are strong fasciculi which pass from the second range of carpal to the metacarpal bones ; with the exception of the little finger there are two fasciculi to each bone, namely, to the index finger, one each from the trapezium and trapezoid ; to the middle finger, one each from the trapezoid and os magnum ; to the ring finger, one each from the os magnum and unciform ; and to the little finger, one from the unciform. The palmar ligaments are thin fasciculi arranged according to the same plan on the palmar surface, but the third metacarpal has three slips, one from the ridge on the trapezium, one from the os magnum, and one from the unciform. The synovial cavity is a continuation of the great synovial cavity of the two rows of carpal bones. The capsular ligament of the thumb is one of the three true capsular ligaments of the skeleton ; the other two being the shoulder and hip. The articulation has a special synovial membrane. The metacarpal bones of the four fingers are firmly connected at their bases by means of dorsal and palmar ligaments, which extend transversely from one bone to the other, and by interosseous liga- ments which pass between their contiguous surfaces. Their lateral articular facets are lined by a reflection of the great synovial mem- brane of the two rows of carpal bones. Actions.—The movements of the metacarpal on the carpal bones are restricted to a slight degree of gliding motion, with the excep- tion of the articulation of the metacarpal bone of the thumb with the trapezium. In the latter, the movements are flexion, extension, adduction, abduction, and circumduction. io. METACARPO-PHALANGEAL ARTICULATIONS.—The meta- carpo-phalangeal articulation is a condyloid joint; and its ligaments four in number :— Anterior, Two lateral, Transverse. The anterior ligaments (glenoid), thick and fibro-cartilaginous, form part of the articulating surface of the joints. They are grooved on their palmar surface for the lodgment of the flexor tendons, arid by their deep aspect form part of the articular surface for the head of the metacarpal bone. At each side they are continuous with the lateral ligaments. The lateral ligaments are strong narrow fasciculi, holding the bones together at each side. The transverse ligament is a strong ligamentous band passing across the heads of the metacarpal bones of the four fingers, and connected with the anterior ligaments. The expansion of the extensor tendon over the back of the fingers takes the place and performs the office of a posterior ligament. Actions,—The chief motions which this articulation admits of 210 ARTICULATIONS OF THE PHALANGES. are flexion and extension. When the finger is extended the lateral ligaments are in a condition of relaxation, and adduction, abduction, and circumduction take place ; when, however, the finger is flexed, Fig. 172. — Lateral and anterior liga- ments of meta- carpo - phalangeal and interplialan- geal joints ; show- ing their condition during flexion. 1, 1, 1. Posterior part of lateral ligaments tense. 2, 2, 2. Anterior ligaments. 2, 2, 2. Anterior part of lateral ligaments relaxed. these ligaments become tense and all lateral movement is pre- vented. 11. ARTICULATIONS OF THE PHALANGES.—These articulations are ginglymus joints ; and furnished with three ligaments :— Anterior, Two lateral. The anterior ligament, firm and fibro-cartilaginous, forms part of the articular surface for the head of the phalanges ; while exter- nally it is grooved for the reception of the flexor tendons. The lateral ligaments are very strong, and the principal bond of connection between the bones. The extensor tendon takes the place and performs the office of a posterior ligament. Actions.—The movements of the phalangeal joints are flexion and extension, these movements being more free between the first and second than between the second and third. LIGAMENTS OF THE LOWER EXTREMITY. The ligaments of the lower extremity, like those of the upper, may be arranged in the order of the joints to which they belong ; these are :— 1. Hip-joint. 2. Knee-joint. 3. Articulations between the tibia'and fibula. 4. Ankle-joint. 5. Articulations of the tarsal bones. 6. Tarso-metatarsal articulations. 7. Metatarso-phalangeal articulations. 8. Articulations of the phalanges. 1. HIP-JOINT.—The articulation of the head of the femur with the acetabulum constitutes an enarthrosis, or ball-and-socket joint. HIP-JOINT. The articular surfaces are—the cup-shaped cavity of the acetabu- lum and the rounded head of the femur ; the ligaments are five in number, viz. :— 211 Capsular, Ilio-femoral, Teres, Cotyloid, Transverse. The capsular ligament (Fig. 160,8) is a strong ligamentous capsule embracing the acetabulum superiorly, the neck of the femur below, and connecting the two bones firmly together. The pelvic origin of the fibres extends superiorly as high as the base of the anterior inferior iliac spine, posteriorly it is connected with the ilium and ischium only a few lines from the margin of the acetabulum, interiorly it is attached to the outer lip of the groove between the ischial tuberosity and acetabulum, while in front it springs from the transverse ligament, the pubes near the notch, and the pectineal eminence. On the femur the capsule gets attached in front to the spiral line, above to the base of the great trochanter, behind to the junction of the middle and outer thirds of the neck, and reaches below to within three-quarters of an inch of the lesser trochanter. The capsule is composed of longitudinal and circular fibres; the former are chiefly found on the front, and the latter are most numerous on the back. The longitudinal fibres at the back of the capsule are almost entirely confined to the surface next the synovial membrane ; after running outwards for some distance they are re- flected along the neck of the femur to the articular margin ; from their close connection with the bone they often prevent the separa- tion of the fragments in intracapsular fracture of the neck, and have received the name of retinacula. The capsule receives strengthening bands from the tendons of the rectus, ilio-psoas, gluteus minimus, and obturator externus. The ilio-femoral ligament is the chief accessory band of the capsule. It is placed anteriorly, and is connected above with the ilium immediately below and behind the anterior inferior spine ; it is attached below to the front of the great trochanter and spiral line as far as the inner border of the shaft of the femur. The fibres at the inner and outer borders of this ligament are thicker than the middle ones, and as they diverge from each other they present the appear- ance of an inverted Y ; hence this ligament has been described by Bigelow under the name of the Y-shaped ligament: it must, how- ever, be borne in mind that the interspace between the two limbs is filled in by radiating fibres, so that strictly no true Y-shaped liga- ment exists. Other accessory bands of fibres exist on the superior, inferior, and anterior aspects of the capsule ; these have been named respectively, ilio-trochanteric, ischio-capsular, and pubo-femoral liga- ments. The ligamentum teres (Fig. 161, 7), triangular in shape, is attached by a round apex to the depression just below the middle of the head of the femur, and by its base, which separates into two fasciculi, into 212 the borders of the notch of the acetabulum, where it is connected with the transverse ligament. It is formed by a fasciculus of fibres of variable size, surrounded by synovial membrane ; sometimes the synovial membrane is present without the fibres, or the ligament is wholly absent. The round ligament limits adduction in the flexed position, and thus resists dislocation of the head of the femur on to the dorsum of the ilium ; it also limits external rotation when the limb is partly flexed. The cotyloid ligament (Fig. 161, 6) is a prismoid cord of fibro- cartilage, attached around the margin of the acetabulum, and serving to deepen that cavity and protect its edges. It is thicker at the upper and posterior border of the acetabulum than in front, is inclined inwards towards the acetabulum, and consists of fibres which arise from the whole circumference of the brim, and interlace with each other at acute angles. The transverse ligament is a strong fasciculus of ligamentous fibres, continuous with the cotyloid ligament, and stretching across the notch of the acetabulum. It converts the notch into a foramen, through which the articular branches of the internal circumflex and obturator artery enter the joint. The fossa at the bottom of the acetabulum is filled with a mass of fat, covered by synovial membrane, which serves as an elastic cushion for the head of the bone during its movements. This was described by Havers as the synovial gland. The synovial membrane is extensive ; it commences at the margin of the head of the femur, and is continued around the liga- mentum teres to the acetabulum, whence it is reflected on the inner surface of the capsular ligament back to the head of the bone. Capsular Muscles.—The muscles immediately surrounding and in contact with the hip-joint are—in front, psoas and iliacus, sepa- rated from the capsular ligament by a large synovial bursa ; above, short head of the rectus and gluteus minimus ; behind, pyrifor- mis, gemellus superior, obturator interims, gemellus inferior, and quadratus femoris; and at the inner side, obturator externus and pectineus. Actions.—The movements of the hip-joint are very extensive : they are flexion, extension, adduction, abduction, circumduction, and rotation. When the knee is flexed, flexion of the hip-joint is limited only by the contact of the thigh with the abdominal wall, but when the knee is extended the ham-string muscles check the movement in most persons when the leg forms an angle of 750 with the body. Extension is checked by the ilio-femoral ligament; rotation outwards by the outer part of the ilio-femoral ligament and ligamentum teres ; rotation inwards by the back part of the capsule, the iscliio-capsular ligament, and the muscles at the back of the joint. Adduction is limited by the ilio-femoral ligament and upper part of capsule ; abduction bv the pubo femoral band and lower part of capsule. Nerve-supply. — Obturator, accessory obturator, and anterior HIP-JOINT. KNEE-JOINT. 213 crural from the lumbar plexus ; branches of the great sciatic, and of the nerve to the quadratus femoris, from the sacral plexus. Bursae.—Nine bursae are found in the neighbourhood of the hip- joint, five in front and four behind. Those on the front are as follows :—One of large size between the ilio-psoas tendon and the capsule, which often communicates with the cavity of the joint; another between the tendon of the gluteus medius and the great trochanter ; a third between the gluteus minimus and the great trochanter ; a fourth between the gluteus maximus and vastus ex- ternus ; and a fifth of large size ana often multilocular between the gluteus maximus and great trochanter. The bursae situated at the back of the joint are :—One beneath the tendon of the obturator externus, another between the quadratus femoris and great tro- chanter, a third between the capsule and common tendon of the obturator internus and gemelli, and a fourth between the quadratus femoris, obturator externus, and the back part of the capsule. 2. KNEE-JOINT.—The knee is a ginglymus articulation of large size, and provided with numerous ligaments ; the latter may be divided into an external and an internal set. Anterior or ligamentum patellae, Posterior or ligamentum posticum Winslowii, Internal lateral, Two external lateral, Capsular ligament, External ligaments. Anterior or external crucial, Posterior or internal crucial, Transverse, Coronary, Ligamentum mucosum, > f ] , two ligamenta alarm, y u Two semilunar fibro-cartilages, Synovial membrane. Internal ligaments. The anterior ligament, or ligamentum patellae, is the prolonga- tion of the tendon of the extensor muscles of the thigh downwards to the tubercle of the tibia. Between the upper part of this liga- ment and the knee-joint a pad of fat is placed, and between its lower part and the tibia there is a synovial bursa. The posterior ligament, or ligamentum posticum Winslowii, is a broad expansion of ligamentous fibres, which covers the whole of the posterior aspect of the joint. It is divisible into two lateral portions, which invest the condyles of the femur, and a central portion which is depressed, and formed by the interlacement of fasciculi passing in different directions. The strongest of these fasciculi is derived from the tendon of the semi-membranosus, and passes obliquely upwards and outwards from the posterior part of the inner tuberosity of the tibia to the external condyle of the femur. Other accessory fasciculi are given off by the tendon of the popliteus 214 KNEE-JOINT. and heads of the gastrocnemius. The middle portion of the liga- ment supports the popliteal artery and vein, and is perforated by several openings for the passage of branches of the azygos articular artery and the nerves of the joint. The internal lateral ligament is a broad and trapezoid layer of ligamentous fibres attached above to the tubercle on the internal condyle of the femur, and below to the inner tuberosity and upper part of the shaft of the tibia. It is intimately connected with the edge of the internal semilunar cartilage and with the coronary ligament, and by its posterior edge becomes blended with the ligambnt of Winslow. It is crossed at its lower part by the tendons of the sartorius, gracilis, and semi-tendinosus, from which it is separated by a synovial bursa, and has passing beneath it the anterior slip of the semi- membranosus tendon and the in- ferior internal articular artery. External Lateral Ligaments. —The long external lateral liga- ment is a strong and round cord, which descends from the pos- terior part of the tubercle on the external condyle of the femur to the outer part of the head of the fibula. It is covered in by the tendon of the biceps, and has passing beneath it the tendon of origin of the popliteus muscle, and the inferior external arti- cular artery. The short external lateral ligament is an irregular fasci- culus situated behind the pre- ceding, arising from the external condyle near the origin of the head of the gastrocnemius muscle, and inserted into the middle of the outer surface of the head of the fibula. It is firmly connected with the external semilunar fibro-cartilage, and appears principally intended to connect that cartilage with the fibula: sometimes it is lost superiorly in the capsular ligament without reaching the femur The capsular ligament consists of thin fibres which fill up the interval left between the patella in the centre and the lateral liga- Fig. 173.—Anterior view of the ligaments of the knee-joint. 1. Ligamentum pa- tellae. 2. Patella covered by ligamentous fibres. 3. Tubercle of tibia. 4. Tendon of rectus. 5. Long external lateral liga- ment. 6, 6. Internal lateral ligament. 7. Head of fibula. 8. Insertion of sartorius. 9. Tendon of popliteus. 10. Insertion of gracilis, n. Tendon of adductor magnus prolonged into internal lateral ligament. i2. Insertion of semi-tendinosus. KNEE-JOINT. 215 ments on each side ; the fibres are attached above to the margin of the articular surface of the femur, and to the upper edge and lateral margins of the patella, while they are inserted below into the inner and outer tuberosities of the tibia. They are intimately connected with the lateral expansions of the tendons of the vastus externus, vastus internus, and crureus, and receive additional fibres from the tendons of the biceps, semi- tendinosus, and sartorius. The true ligaments within the joint are the crucial, transverse, and coronary. The anterior or external crucial ligament arises from the depression on the head of the tibia in front of the spinous process, and passes upwards and backwards to be inserted into the inner surface of the outer condyle of the femur, as far back as its posterior border. It is smaller than the posterior. The posterior or internal crucial ligament arises from the depression on the head of the tibia behind the spinous process, and passes upwards and forwards to be inserted into the intercondylar hollow, and outer surface of the inner condyle of the femur. This ligament is less oblique and larger than the anterior. The anterior crucial ligament limits extension, and the posterior limits flexion ; they also limit rotation when the leg is flexed. The transverse ligament is a small slip of fibres which extends transversely from the external semilunar fibro-carti- lage, near its anterior extremity, to the anterior convexity of the internal cartilage. The coronary ligaments are the short fibres by which the convex borders of the semilunar cartilages are connected to the head of the tibia and ligaments surrounding the joint. The semilunar fibro-cartilages are two falciform plates of fibro- Fro. 174.—Posterior view of the ligaments of the knee-joint. 1, 1. Internal lateral liga- ment. 2. Long external lateral ligament. 3. Tendon of semi-membranosus. 4, 4. Popliteus. s, 5. Prolongations of tendon of semi-membranosus. 6. Outer head of gastrocnemius. 7. Inner head of gastroc- nemius. 8, 15. Posterior ligament (of Winslow). 9. Opening in capsule. 10. Posterior superior tibio-fibular ligament. 11. Tendon of adductor magnus. 12. Tendon of biceps. 13. Prolongation from tendon of semi-membranosus to posterior ligament. 216 KNEE-JOINT. cartilage, situated on the head of the tibia around its margin, and serving to deepen the surface of articulation for the condyles of the femur. They are thick along their convex border ; thin and sharp along their concave edge. Each cartilage covers about two-thirds of the corresponding articular surface of the tibia, leaving the inner third uncovered ; both surfaces are covered by synovial membrane. The internal semilunar fibro-cartilage forms an oval cup for the reception of the internal condyle of the femur : it is connected by its convex border with the head of the tibia and internal and posterior ligaments, by means of its coronary ligament; and by its two extremities is firmly implanted into the depression before and behind the spinous process. The external semilunar fibro-carti- lage bounds a circular fossa for the external condyle ; it is connected by its convex bor- der with the head of the tibia, and to the external and posterior liga- ments by its coro- nary ligament; by its two extremi- ties it is inserted intothedepression between the two projections which constitute the spinous process of the tibia ; being placed between the attached ends of the internal cartilage. The two extremities of the external cartilage, being inserted into the same fossa, form an almost complete circle, and the cartilage, being somewhat broader than the internal, covers more of the articular surface of the tibia. The external semilunar fibro-cartilage, besides giving off a fasci- culus from its anterior border to constitute the transverse ligament, is continuous by some of its fibres with the extremity of the ante- rior crucial ligament: posteriorly it divides into three slips ; one, a strong cord, ascends obliquely forwards to be inserted into the anterior part of the inner condyle of the femur in front of the pos- terior crucial ligament; another is the fasciculus of insertion into the fossa of the spinous process ; while the third, of small size, is continuous with the posterior part of the anterior crucial liga- ment. 1 he ligamentum mucosum is a slender conical process of synovial membrane enclosing a few ligamentous fibres which proceed from the transverse ligament. It is connected, by its apex, with the Pig. 175.—The right knee-joint laid open from the front in order to show the internal ligaments. 1. Cartilaginous surface of the lower extremity of the femur; the figure 5 rests on the external, the figure 3 on the internal, condyle. 2. Anterior crucial ligament. 3. Posterior crucial ligament. 4. Transverse ligament. 5. Attachment of the ligamen- tum mucosum ; the rest has been removed. 6. Internal semilunar fibro-cartilage. 7. External fibro-cartilage. 8. Part of the ligamentum patel- lae turned down. 9. Bursa situated between the liga- mentum patellae and the head of the tibia, laid open. 10. Antero-superior tibio-fibular ligament. ix. Interosseous membrane. KNEE-JOINT. 217 anterior part of the condylar notch, and, by its base, is lost in the mass of fat which projects into the joint beneath the patella. The alar ligaments are two fringed folds of synovial membrane, extending from the ligamentum mucosum, along the edges of the mass of fat, to the sides of the patella. The synovial membrane of the knee-joint is by far the most extensive in the body. It commences near the margins of the carti- laginous surfaces of the condyles of the femur, it covers both surfaces of the semilunar fibro-cartilages, and is reflected upon the crucial ligaments, and inner surface of the ligaments which form the circum- ference of the joint. On each side of the patella it lines the capsular Fig. 176.—Longitudinal section of the left knee- joint, showing the reflections of its synovial membrane. 1. Cancellous structure of the lower part of the femur. 2. Tendon of the extensor muscles of the leg. 3. Patella. 4. Ligamentum patellae. 5. Cancellous struc- ture of the head of the tibia. 6. A bursa situated between the ligamentum patellae and head of the tibia. 7. Mass of fat project- ing into the cavity of the joint below the patella. ** The synovial membrane. 8. The pouch of synovial membrane which ascends between the tendon of the extensor muscles of the leg and front of the lower extremity of the femur. 9. One of the alar ligaments; the other has been removed with the opposite section. 10. Ligamentum mucosum left en- tire ; the section being made to its inner side. 11. Anterior or external crucial ligament. 12. Posterior ligament. ligament, and forms a poucli of considerable size between the extensor tendon and front of the femur; it passes upwards for fully two inches above the patella, and is supported and raised during the movements of the limb by a small muscle, the subcrureus, which is inserted into it. It also forms the folds in the interior of the joint, called “ ligamentum mucosum ” and “ ligamenta alaria.” Between the ligamentum patellae and synovial membrane is a considerable mass of fat, which presses the membrane towards the interior of the joint, and occupies the fossa between the condyles. Actions.—The knee-joint is one of the strongest of the articula- tions of the body, while, at the same time, it admits of the most perfect degree of movement in the direction of flexion and extension. During flexion the articular surface of the tibia glides forward on the condyles of the femur ; the lateral ligaments, the posterior ligament, and the anterior crucial ligament are relaxed; while the ligamentum patellae being on the stretch, serves to press the adipose mass behind it into the vacuity formed in the front of the joint. In complete flexion the posterior crucial ligament is rendered tense, 218 KNEE-JOINT. but flexion is also limited during life by the contact of the leg with the thigh. In complete extension all the ligaments are put on the stretch, with the exception of the ligamentum patellae and the posterior crucial ligament. In the movements of flexion and ex- tension the patella in turn presents to the femoral surface each of the three facets into which the condylar surfaces of that bone are divided, this coaptation being associated with gliding. At the termination of the act of flexion the patella rests with its inner vertical facet (seventh facet) against the outer part of the internal condyle, and its upper and outer facet against the front of the external condyle. At the end of extension the external condyle reaches its resting position before the internal, so that the latter continues to move backwards, thus rotating the femur inwards upon the tibia. When the knee is semi-flexed, a partial degree of rotation is permitted. Bursae.—The bursa? in the neighbourhood of the knee-joint are numerous and important; three large ones are placed in front, and numerous small ones at the back of the joint. Those in front are —first, one, large and superficial, placed between the patella and subcutaneous tissue, it is this which becomes enlarged in the disease known as “ housemaid’s knee ; ” second, one between the common extensor tendon and the lower part of the shaft of the femur, it frequently communicates with the synovial pouch of the joint; the third is placed between the ligamentum patellae and the head of the tibia ; it also, sometimes, communicates with the cavity of the joint. The bursa? at the back of the joint are chiefly connected with the tendons of muscles ; the most important are the following:—One placed between the tendons of the semi-membranosus and inner head of the gastrocnemius and the internal condyle ; this is the largest bursa in the popliteal region, and extends from the posterior in- ferior part of the internal condyle to the back of the inner tubero- sity of the tibia as low down as the upper border of the popliteus muscle. A second bursa lies between the anterior surface of the semi-membranosus tendon and the inner tuberosity of the tibia. Other bursa? exist, between the tendon of the popliteus and the external lateral ligament, between the same tendon and the outer tuberosity of the tibia, between the tendon of the biceps and the external lateral ligament, and beneath the outer head of the gas- trocnemius. Nerve-supply.—Branches of the obturator, anterior crural, ex- ternal and internal popliteal. 3. ARTICULATIONS BETWEEN THE TIBIA AND FIBULA.—The tibia and fibula are held firmly connected by means of seven liga- ments, namely: — Anterior, Posterior, above. Anterior, Posterior, below. Interosseous membrane, Interosseous inferior, Transverse. TIBIO-F1BULAK AETICULATIONS. 219 The anterior superior tibio-fibular ligament is a strong fasci- culus of parallel fibres passing obliquely downwards and outwards from the outer tuberosity of the tibia to the anterior surface of the head of the fibula. The posterior superior tibio-fibular ligament, thicker and stronger than the anterior, is disposed in a similar manner on the posterior surface of the joint. It is covered by the tendon of the popliteus. Within the articulation there is a synovial membrane which is sometimes continuous with that of the knee-joint. The interosseous membrane is a broad layer of aponeurotic fibres which pass obliquely downwards and outwards, from the sharp ridge on the tibia to the inner edge of the fibula, and are crossed by a few fibres taking the opposite direction. The liga- ment is deficient above, leaving a considerable interval between the bones, through which the anterior tibial artery takes its course forward to the anterior aspect of the leg; and per- forated below, near its lower third, for the anterior peroneal artery and vein. The interosseous membrane is in relation, in front, with the tibialis anticus, extensor longus digitorum, extensor proprius hallucis, anterior tibial vessels and nerve, and anterior peroneal artery ; behind, with the tibialis posticus, flexor longus hallucis, flexor longus digitorum, and posterior peroneal artery. The inferior interosseous ligament consists of short and strong fibres, which hold the bones firmly together inferiority, where they are nearly in contact; it is continuous above Avith the interosseous membrane. This articulation is so firm, that the fibula is broken when an attempt is made to rupture the ligament. The anterior inferior tibio-fibular ligament is a broad band, consisting of two fasciculi of parallel fibres which pass obliquely across the anterior aspect of the articulation of the two bones at their inferior extremity, from tibia to fibula. The posterior inferior tibio-fibular ligament is a similar band on the posterior surface of the articulation. Both ligaments project somewhat below the margin of the bones, and serve to deepen the cavity of articulation with the astragalus. The transverse ligament is a narrow band of ligamentous fibres, continuous with the preceding, and passing transversely across the back of the ankle-joint between the two malleoli. Fig. 177.—Posterior view of the ankle- joint. 1. Lower part of the in- terosseous mem- brane. 2. Poste- ro-inferior tibio- fibular ligament. 3. Transverse liga- ment. 4. Internal lateral ligament. 5. Posterior fasci- culus of the exter- nal lateral liga- ment. 6. Middle fasciculus of the external lateral ligament. 7. Syn- ovial membrane of the ankle-joint. 8. Posterior tube- rosity of the os calcis. 220 ANKLE-JOINT. The synovial membrane of the inferior tibio-fibular articulation is a fold of the synovial membrane of the ankle-joint, reflected upwards for a short distance between the two bones. Actions.—Between the tibia and fibula there exists a slight degree of movement, which is calculated to enable the latter to resist injury by yielding for a trifling extent to forcible pressure. 4. ANKLE-JOINT.—The ankle is a ginglymus articulation ; the surfaces entering into its formation are the under surface of the tibia with its malleolus and the malleolus of the fibula, above ; and the surface of the astragalus with its two lateral facets, below. The ligaments are four in number :— Anterior, Internal lateral, External lateral, Posterior. The anterior ligament is a thin membranous layer, passing from the margin of the tibia to the astragalus in front of its articular sur- Fig. 178.—Ligaments of inner side of ankle and foot. 1,2, 3, 4. Different parts of internal lateral ligament of ankle. 5, 6. Inferior calcaneo-scaplioid ligament. 7. Internal ligament between internal cuneiform and first metatarsal. 8. Ligament between the scaphoid and internal cuneiform. 9. Inferior ligament between internal cuneiform and first metatarsal. 10. Inferior ligament of first metatarso- phalangeal joint. face. It is in relation, in front, with the tendons of the extensors of the great and lesser toes, tibialis anticus, peroneus tertius, and ante- rior tibial vessels and nerves. Posteriorly it lies in contact with a stratum of extra-synovial adipose tissue and the synovial membrane. The internal lateral or deltoid ligament is a triangular layer of fibres, attached superiorly, by its apex, to the internal malleolus ; interiorly, by an expanded base, to the astragalus, os calcis, and scaphoid bones. Beneath the superficial layer of this ligament is a stronger and thicker fasciculus, which connects the apex of the internal malleolus with the side of the astragalus. The internal lateral ligament is covered in and partly concealed by the tendon of the tibialis posticus, and, at its posterior part, is in ANKLE-JOINT. 221 relation with the tendon of the flexor longus digitorum and flexor longus hallucis. The external lateral ligament consists of three strong fasciculi, which proceed from the inner side of the external malleolus, and radiate in three different directions. The anterior fasciculus passes forward, to be attached to the astragalus ; the posterior, backward, to be connected with the astragalus posteriorly ; and the middle, longer than the other two, descends to be inserted into the outer side of the os calcis. The posterior ligament consists of a few scattered and thin fibres which are attached above to the external malleolus, the back part of the lower end of the tibia, and to the posterior inferior tibio- flbular ligament, and below to the posterior surface of the astragalus, from the external to the internal lateral ligaments. The synovial membrane is reflected upon the anterior and lateral Fio. 179.—Ligaments of outer side of ankle and foot. 1. Anterior-inferior tibio- fibular ligament. 2. Middle fasciculus of external lateral ligament of ankle. 3. Anterior fasciculus. 4. External calcaneo-astragaloid ligament. 5. External calcaneo-scaphoid ligament. 6. Interosseous calcaneo-astragaloid ligament. 7. Superior astragalo-scaphoid ligament. 8. External calcatieo-cuboid ligament. 9. Superior scapho-cuneiform ligament. 10. Internal calcaneo-cuboid ligament. 11. Dorsal ligament between external and middle cuneiform. 12. Dorsal ligament between scaphoid and cuboid. 13. Dorsal ligament between external cuneiform and third metatarsal. 14. Dorsal ligament between cuboid and fifth metatarsal. 15. Dorsal ligament between middle cuneiform and second metatarsal. 16. Dorsal ligament between cuboid and third and fourth metatarsals. 17, 18, 19, 20. Dorsal ligaments between bases of metatarsal bones. ligaments, and on the transverse and posterior ligaments behind ; it also sends a fold upwards between the tibia and fibula. Actions.—The movements are mainly those offlexion and extension, the latter being accompanied by a slight inward movement of the toes, in consequence of the outer border of the articular surface of the astragalus being longer than the inner. Both the cupped lower end of the tibia and the corresponding surface of the astragalus are wider in front than behind ; hence, in complete extension the narrow part of the latter comes to occupy the wide part of the former, ARTICULATION OF THE TARSAL BONES. and a limited degree of lateral motion is thus allowed ; in flexion, on the other hand, they fit accurately to each other, thus securing that fixation so necessary to the erect posture. Bursae.—The bursae in connection with the ankle-joint are chiefly of the ensheathing or vaginal variety, and are continued for some distance along the tendons on the front and back of the joint. The annular ligament binding down the tendons in front of the joint is divided into three compartments, each of which has its special synovial sheath. The first gives passage to the tibialis anticus, the second to the extensor longus hallucis, and the third is common to the extensor longus digitorum and peroneus tertius. Behind the ankle there is a bursa common to the two peronei muscles, one in the course of the flexor longus digitorum, and one in that of the tibialis posticus. Nerve-supply.—Branches of the anterior and posterior tibial nerves. 5. ARTICULATION OF THE TARSAL BONES.—The ligaments which connect the seven bones of the tarsus to each other are of three kinds:— Dorsal, Plantar, Interosseous. The dorsal ligaments are small fasciculi of parallel fibres, which pass from each bone to all the neighbouring bones with which it articulates. The only dorsal ligaments deserving of particular men- tion are the external and posterior astragalo-calcaneal, which, with the interosseous ligament, complete the articulation of the astra- galus with the os calcis; the superior and internal calcaneo-cuboid ligaments ; and the superior astragalo-scaphoid ligament. The internal calcaneo-cuboid, and superior calcaneo-scaphoid ligament, which are closely united posteriorly in the deep groove which inter- venes between the astragalus and os calcis, separate anteriorly to reach their respective bones ; they form the principal bond of con- nection between the first and second range of bones of the foot. It is the division of this portion of these ligaments that demands the careful attention of the surgeon in performing Chopart’s operation. The plantar ligaments have the same disposition on the plantar surface of the foot; three of them, however, are of large size, and have especial names, viz., the Calcaneo-scaphoid, Long calcaneo-cuboid, Short calcaneo-cuboid. The inferior calcaneo-scaphoid ligament is a broad and fibro- cartilaginous band of ligament which passes forward from the an- terior and inner border of the os calcis to the edge of the scaphoid bone. Besides connecting the os calcis and scaphoid, it supports the astragalus, and forms part of the cavity in which the rounded head of the latter bone is received. It is lined on its upper surface by the synovial membrane of the astragalo-scaphoid articulation. ARTICULATION OF THE TARSAL BONES. 223 This ligament is the main support of the arch of the foot, and is sometimes called the “ spring ” ligament; it is braced up by the tendon of the tibialis posticus, which runs beneath it. The firm connection of the os calcis with the scaphoid bone, and the feebleness of the astragalo-scaphoid articulation, are conditions favourable to the occasional dislocation of the head of the astragalus. The long calcaneo-cuboid ligament or ligamentum longum plantse is a long band of ligamentous fibres, which proceeds from the under surface of the os calcis to the rough surface on the under part Fig. 180.—Ligaments of the sole of the foot. i. Point of attachment of tendon Achilles. 2. Internal malleolus. 3. Posterior tuberosity of os calcis. 4. Posterior part of astragalus. 5. External tubercle on under surface of os calcis. 6. Posterior calcaneo-astragaloid liga- ment. 7. Internal tubercle of os calcis. 8 and 12. Internal lateral ligament. 9. Long plantar liga- ment. 10. Groove on sustentaculum tali for flexor proprius hallucis. n and 16. Short plantar ligament. 13 and 23. Tendon of peroneus longus. 14. Inferior calcaneo- scaphoid ligament. 15 and 25. Sheath of peroneus longus. 17. Plantar ligament between fourth and fifth metatarsals. 18. Tubercle of scaphoid. 19. Plantar ligament between third and fourth meta- tarsals. 20. Plantar ligament be- tween scaphoid and internal cunei- form. 21. Fifth metatarsal. 22. Internal cuneiform. 24. First meta- tarsal. of tlie cuboid bone, its fibres being continued onwards to the base of the second, third, and fourth metatarsal bones. This ligament forms the inferior boundary of the canal in the cuboid bone, through which the tendon of the peroneus longus passes to its insertion into the base of the metatarsal bone of the great toe. The short calcaneo-cuboid or ligamentum breve plantse is situated closer to the bones than the long plantar ligament, from which it is separated by adipose tissue ; it is broad and extensive, and ties the under part of the os calcis and cuboid bone firmly together. The interosseous ligaments are five in number ; they are short and strong ligamentous fibres situated between adjoining bones, and firmly attached to their rough surfaces. One of' these,"astragala- SYNOVIAL CAVITIES OF THE TARSUS. 224 calcaneal, is lodged in the groove between the upper surface of the os calcis and the lower of the astragalus. It is large and very strong, consists of vertical and oblique fibres, and serves to unite the os calcis and astragalus solidly together. The second interosseous liga- ment, also very strong, is situated between the sides of the scaphoid and cuboid bone ; the three remaining interosseous ligaments con- nect strongly together the three cuneiform bones and the cuboid. The synovial membranes of the tarsus are four in number : one, for the posterior astragalo-calcaneal articulation ; a second, for the anterior astragalo-calcaneal and astragalo-scaphoid articulation ; oc- casionally an additional small synovial membrane is found in'the Fig. i8i.—Diagram showing the arrangement of the synovial membranes of the tarsal joints, i. Synovial membrane of the ankle-joint, n. That between the back of the astragalus and. os calcis. nr. That between the astragalus and scaphoid, and between the front of the astragalus and os calcis. iv. Between the os calcis and cuboid, v. Between the cuneiform bones and scaphoid, vi. Between the internal cuneiform and metatarsal of big toe. vn. Between the middle meta- tarsal and two outer cuneiform bones, vm. Between the cuboid and outer meta- tarsals. IX. Between the third and fourth metatarsals, i. Tibia. 2. Astragalus. 3- Ds calcis. 4. Scaphoid. 5. Cuboid. 6. External cuneiform. 7. Middle, and 8, Internal cuneiform. 9, 10, 11, 12, 13. Metatarsal bones. Interosseous ligaments are shown connecting the several bones of the tarsus and metatarsus. anterior astragalo-calcaneal joint; a third, for the calcaneo-cuboid articulation ; and a fourth, the large tarsal synovial membrane for the articulations between the scaphoid and three cuneiform bones, the cuneiform bones with each other, the external cuneiform bone with the cuboid, and the two outer cuneiform bones with the bases of the second and third metatarsal bones. The prolongation which reaches the metatarsal bones passes forward between the internal and middle cuneiform bone. The synovial membrane between the two outer cuneiform and second and third metatarsal bones is often distinct from the large one ; it is so represented in Fig. 181, vn. A small synovial membrane is sometimes met with between the contiguous surfaces of the scaphoid and cuboid bone. TARSO-METATARSAL ARTICULATION. 225 Actions.—The movements permitted by the articulation between the astragalus and os calcis, are a slight degree of gliding, in the direction forwards and backwards, and laterally from side to side. The movements of the second range of tarsal bones are very trifling, being greater between the scaphoid and three cuneiform bones than in the other articulations. The movements occurring between the first and second range are the most considerable ; they are adduction and abduction; and, in a minor degree, flexion, which increases the arch of the foot, and extension, which flattens the arch. 6. TARSO-METATARSAL ARTICULATION.—The ligaments of this articulation are :— Dorsal, Plantar, Interosseous. The dorsal ligaments connect the metatarsal to the tarsal bones, and the metatarsal bones with each other. The base of the second metatarsal bone, articulating with the three cuneiform bones, receives a ligamentous slip from each, while the rest articulating with a single tarsal bone receive only a single tarsal slip. The plantar ligaments have a similar disposition on the plantar surface. The interosseous ligaments are situated between the bases of the metatarsal bones of the four lesser toes ; also between the base of the second and third metatarsal bones and the internal and external cuneiform bones. The metatarsal bone of the second toe being implanted by its base between the internal and external cuneiform bones, is the most strongly articulated of all the metatarsal bones. This disposition must be recollected in amputation at the tarso-metatarsal articu- lation. The synovial membranes of the tarso-metatarsal articulation are three in number : one for the metatarsal bone of the great toe ; one for the second and third metatarsal bones, which is continuous with the great tarsal synovial membrane ; and one for the fourth and fifth metatarsal bones. Actions.—The movements of the metatarsal on the tarsal bones and on each other are very slight; they are such only as contribute to the strength of the foot, by permitting a certain degree of yielding to opposing forces. 7. METATARSO PHALANGEAL ARTICULATION.—The ligaments of this articulation, like those between the first phalanges and meta- carpal bones of the hand, are :— Inferior or plantar, Two lateral, Transverse. The inferior or plantar ligaments, thick and fibro-cartilaginous, form part of the articulating surface of the joint. The lateral ligaments, short and very strong, are situated one on each side of the joint. The transverse ligament is a strong band, which passes trans- versely between the plantar ligaments. 226 ARTICULATION OF THE PHALANGES. The expansion of the extensor tendon supplies the place of a dorsal ligament. Actions.—The movements of the first phalanges on the rounded heads of the metatarsal bones are, flexion, extension, adduction, and abduction. 8. ARTICULATION OF THE PHALANGES—The ligaments of the phalanges are the same as those of the fingers, and have the same disposition ; their actions are also similar. They are :— Inferior or plantar, and, Two lateral. PART IV. MYOLOGY. In this section will be described the arrangement, attachments, and actions of fhe voluntary muscles, and the disposition of the fascia' supporting or connected with them. MUSCLES present various modifications in the arrangement of their fibres in relation to their tendinous structure. Sometimes they are longitudinal, and terminate at each extremity in tendon, the entire muscle being fusiform in shape ; in other situations tliev are disposed like the rays of a fan, converging to a tendinous point, as the temporal, pectoral, glutei, &c., and constitute a radiate muscle. Again, they are penniform, converging like the barbs of a feather to one side of a tendon, which runs the whole length of the muscle, as in the peronei; or bipenniform, converging to both sides of the tendon. In other muscles the fibres pass obliquely from the surface of a tendinous expansion spread out on one side, to that of another extended on the opposite side, as in the semi-membranosus ; or, they are composed of penniform or bipenniform fasciculi, as in the deltoid, and constitute a compound muscle. In the broad muscle the tendon is spread out so as to form an expansion, called aponeurosis. The muscles are all symmetrical, and, with the exception of the sphincters and diaphragm, are arranged in pairs. It is calculated that they number about 240 pairs, and that the weight of the total mass of muscle is about 63 lbs. in a man whose total body-weight is 150 lbs. The nomenclature of muscles is generally derived from some prominent character which the muscle presents ; thus, some are named from their situation, as the tibialis, peroneus, brachialis, temporal; others from their use, as the flexors, extensors, abductors, levators, tensors, sphincters, &c. Some again from their form, as the trapezius, triangularis, deltoid, rhomboid, scalene, orbicularis, &c. ; and others from their direction, as the rectus, obliquus, trans- versalis, &c. Certain muscles have received names expressive of their attachments, as the sterno-mastoid. sterno-hyoid, &c. ; and others, of their divisions, as the biceps, triceps, digastricus, corn- plexus, &c. 228 In the description of a muscle we express its attachment by the words “ origin ” and “ insertion : ” the term origin is generally applied to the more fixed attachment, or to the point towards which the motion is directed, while insertion is assigned to the more movable point. Where both ends are equally movable the term origin is given to the attachment nearest to the middle line of the body, and that farthest from the middle line is called the insertion. FASCIA (fascia, a bandage) is the name assigned to fibrous laminae of various extent and thickness, which are distributed through the different regions of the body, for the purpose of in- vesting or protecting the softer and more delicate organs. From a consideration of their structure, these fasciae may be arranged into two groups : areolo-fibrous fasciae, and aponeurotic fasciae. The areolo-fibrous or superficial fascia is the common sub- cutaneous investment of the entire body; it is situated immediately beneath the integument over every part of the frame, and is the medium of connection between that layer and the deeper parts. It is composed of areolar and elastic tissue, and contains in its areolae an abundance of adipose tissue, constituting the panniculus adiposus. Fat is, however, absent from the subcutaneous tissue of the penis, scrotum, and eyelids. By dissection, the superficial fascia may be separated into two layers, between which are found the superficial or cutaneous vessels and nerves; as the superficial epi- gastric artery, saphena veins, radial and ulnar veins, superficial lymphatic vessels, and the cutaneous muscles, such as the platysma myoides. The deep layer of this fascia usually forms a more distinct sheet than the superficial, and is almost devoid of fat vesicles. The aponeurotic or deep fascia is the strongest kind of investing membrane ; it is composed of tendinous fibres, running parallel with each other, and connected by other fibres of the same kind passing in different directions, together with areolar tissue and fine elastic fibres. When freshly exposed, it is white, glistening, and iridescent, and is firm, unyielding, and but little elastic. It encloses and forms distinct sheaths to all the muscles and tendons. It is thick on the outer and least protected side of the limb, and thinner at its inner side. It is firmly connected to the bones, and to the prominent points of each region, as to the pelvis, knee, and ankle, in tlie lower ; and to the clavicle, scapula, elbow, and wrist, in the upper extremity. It assists the muscles in their action, by keeping up a tonic pressure on their surface ; aids materially in the circula- tion of the fluids ; and in the palm of the hand and sole of the foot is a powerful protection to the structures which enter into the com- position of those regions. In some situations its tension is regulated by muscular action, as by the tensor vaginae femoris and gluteus maximus in the thigh, by the biceps in the leg, and by the biceps and palmaris longus in the arm ; in other situations it affords an extensive surface for the origin of the fibres of muscles. FASCIA. CRANIAL GROUP OF MUSCLES. 229 The Muscles and Fascia may be arranged in conformity with the general division of the body into—1. Those of the head and neck, 2. Those of the trunk. 3. Those of the upper extremity. 4. Those of the lower extremity. MUSCLES AND FASCIAE OF THE HEAD AND NECK. These admit of subdivision into those of the head and face, and those of the neck. Muscles of the Head and Face.—These muscles may be divided into groups corresponding with the natural regions of the head and face ; the groups are eight in number, namely :— 1. Cranial group. 2. Orbital group. 3. Auricular group. 4. Ocular group. 5. Nasal group. 6. Superior labial group. 7. Inferior labial group. 8. Maxillary group. i. Cranial Group.—Occipito-frontalis. Dissection.—The occipito-frontalis is to he dissected by making a longitudinal incision along the vertex of the head, from the root of the nose to the external occipital protuberance, and a second incision along the forehead and around the side of the head, to join the two extremities of the preceding. Dissect the integument and superficial fascia carefully outwards, beginning at the anterior angle of the flap, where the muscular fibres are thickest, and remove it altogether. This dissection requires care ; for the muscle is very thin, and with- out attention would be raised with the integument. Fascia.—The superficial fascia forms a firm, dense layer, which is closely connected with the integument and the surface of the aponeurosis of the occipito-frontalis ; behind it becomes continuous with the superficial fascia of the neck, and laterally it passes over the temporal aponeurosis, and may be traced nearly as far as the zygoma. It contains between its layers the muscles of the auricle, and the superficial vessels and nerves. There is no deep fascia on the face or head, nor is it required ; for here the muscles are closely applied against the bones, upon which they depend for support, whilst in the extremities the support is derived from the dense layer of fascia by which they are invested, and which forms for each muscle a distinct sheath. The OCCIPITO-FRONTALIS is a broad musculo-aponeurotic layer, which covers the whole side of the vertex of the skull, from the occiput to the eyebrow. It consists of two fleshy bellies and an in- tervening tendinous aponeurosis. The occipital portion arises from the outer two-thirds of the superior curved line of the occipital bone, and from the mastoid portion of the temporal; its fibres pass upwards to be inserted into the posterior margin of the apo- neurosis. The frontal portion is thinner and paler than the occi- pital, but covers a larger extent of surface ; its fibres are continuous 230 with those of the pyramidalis nasi, corrugator supercilii, and orbi- cularis palpebrarum ; immediately above the root of the nose the fibres of the right and left muscles are united, but as they pass upwards a small angular interval is left between them ; they are inserted into the anterior extremity of the aponeurosis. Most of the frontal fibres have no bony attachment, but a few are connected with the internal angular process of the frontal bone. The epicranial aponeurosis of the two sides covers the whole of the vertex of the skull, and terminates in front and behind in narrow processes interposed between the fleshy bellies ; it is attached posteriorly to the occipital protuberance and superior curved line, and receives OCCIPITO-FRONTALIS. Fig. 182.—Muscles of the head and face. 1. Frontal portion of the occipito-frontalis. 2. Its occipital portion. 3. Epicranial aponeu- rosis. 4. Orbicularis palpebrarum, which conceals the corrugator supercilii and tensor tarsi. 5. Pyramidalis nasi. 6. Compres- sor nasi. 7. Orbicularis oris. 8. Levator labii superioris alaique nasi; the adjoining fasciculus be- tween figures 8 and 9 is the labial portion of the muscle. 9. Levator labii.superioris proprius ; the lower part of the levator anguli oris is seen between the muscles 10 and 11. 10. Zygomaticus minor, u. Zygomaticus major. 12. Depressor labii inferioris. 13. Depressor anguli oris. 14. Levator labii in- ferioris. 15. Superficial portion of the masseter. 16. Part of its deep portion. 17. Attraliens auriculam. 18. Buccinator. 19. Attollens auriculam. 20. Temporal fascia covering the temporal muscle. 21. Retraliens auriculam. 22. An- terior belly of the digastric; the tendon is seen: passing through its aponeurotic pulley. 23. Stylo-hyoid muscle pierced by the superior belly of the digastric. 24. Mylo-liyoid. 25. Upper part of the sterno-mastoid. 26. Upper part of the trapezius. The muscle between 25 and 26 is the splenius. iii front the attachment of the anterior bellies, ending about the middle of the forehead. By its lateral margins it gives origin to the attollens and attrahens auriculam muscles, and is continued down to the zygoma as a thin layer of fascia. Relations.—This muscle is in relation by its external surface with the frontal and supraorbital vessels, supraorbital and facial nerves, temporal vessels and auriculo-temporal nerve, occipital vessels and nerves, and integument, to which last it is closely adherent. Its under surface is attached to the pericranium by a loose areolar tissue, which permits considerable movement. Nerve-supply.—Posterior or occipital portion bv the posterior auricular; frontal portion by the temporal—both branches of the facial. ORBICULARIS PALPEBRARUM. 231 Actions.—The occipital portion acting alone draws the scalp backwards. The frontal portion, if it has its fixed point above, draws the eyebrows upwards and produces transverse wrinkles in the forehead, as in expressing surprise, wonder, attention, or terror ; if its fixed point be below it draws forward the scalp. By the alternate action of the two portions the scalp is drawn to and fro on the underlying pericranium. 2. Orbital Group.— Orbicularis palpebrarum, Corrugator supercilii, Tensor tarsi. Dissection.—Great care is requisite in the dissection of the first of these muscles, from the total absence of subcutaneous fat over the eyelids, and the extreme delicacy of the muscular fibres which cover them. A hook should be introduced into the palpebral fissure at the outer canthus, and one of the other hooks of the set fastened to the table, so as to put the eyelids slightly on the stretch ; an incision should be made along the margin of each lid, and the cut already made from the scalp to the root of the nose should be carried onwards to the tip of that organ. The skin is now to be raised from the margin of the lids as a delicate layer not thicker than ordinary tissue-paper. In order completely to expose the orbicularis it will be necessary to make an additional incision, after the skin has been raised from the lids, from the outer canthus of the eye on to the lateral aspect of the head. The ORBICULARIS PALPEBRARUM is a sphincter muscle, sur- rounding the orbit and eyelids, and consists of two portions, external and internal. The external or orbital ‘portion arises from a short tendon, tendo oculi, situated at the inner angle of the eye, and from the internal angular process of the frontal bone ; it encircles the orbit, and is inserted into the nasal process of the superior maxillary and lower border of the tendo oculi, some of its fibres being continuous with the upper segment. This portion of the muscle becomes intimately blended with the occipito-frontalis and corrugator supercilii; it also sends off slips which communicate with the muscles of the upper lip. The internal or palpebral portion forms a curved plane of fibres on the eyelids, thinner and paler than the orbital portion ; externally these fibres are attached to the external palpebral ligament and border of the orbit, some being continuous with the orbital portion ; internally they are attached to the borders of the lacus lachrymalis and tendo oculi. The fibres of the palpebral portion nearest the edges of the lids are thicker than the rest, and are termed ciliary. A few fibres placed within the line of the eyelashes and separated by them from the rest of the orbicularis, have been described as a distinct muscle under the name of ciliary muscle of Riolan. The tendo oculi (internal tarsal ligament), about two lines in length and one in breadth, is attached by one end to the nasal process of the superior maxillary bone, close to the edge of the 232 CORRUGATOR SUPERCILII. orbit; the other end bifurcates to be inserted into the inner ex- tremities of the tarsal plates ; from its posterior aspect is given off a process which spreads over the lachrymal sac, and is attached to the crest of the lachrymal bone ; this is the reflected aponeurosis of the tendo oculi, and serves to protect the lachrymal sac. The external tarsal ligament is a thin band of fibres, con- necting the outer extremity of the eyelids with the malar bone. Relations.—By its superficial surface the muscle is closely ad- herent to the integument, from which it is separated on the eye- lids by a loose areolar tissue. By its deep surface it lies in contact, above, with the upper border of the orbit, corrugator supercilii muscle, frontal and supraorbital vessels, and supraorbital nerve ; below, with the lachrymal sac, levator labii superioris aheque nasi, levator labii superioris proprius, zygomaticus major anu minor muscles, and malar bone ; externally, with the temporal fascia. On the eyelids it is in relation with the broad tarsal ligament and tarsal plates, and by its upper border is connected with the occipito- frontalis. Nerve-supply.—Temporal and malar branches of the facial. The CORRUGATOR SUPERCILII is a small, narrow, and pointed muscle, situated immediately above the orbit, and beneath the upper segment of the orbicularis palpebrarum. It arises from the inner extremity of the superciliary ridge, and passes upwards and out- wards to be inserted into the under surface of the orbicularis pal- pebrarum. Some of the fibres pass through the orbicularis and are inserted into the skin. Relations.—By its superficial surface with the occipito-frontalis and orbicularis palpebrarum ; by its deep surface with the frontal bone and supra-trochlear nerve. Nerve-supply.—The facial nerve. The TENSOR TARSI (Horner’s muscle) is a thin plane of mus- cular fibres, about three lines in breadth and six in length. It is best dissected (after the dissection of the orbit has been completed) by separating the eyelids from the eye, and turning them over the nose without disturbing the tendo oculi; then dissect away the small fold of mucous membrane called plica semilunaris, and some loose areolar tissue under which the muscle is concealed. It arises from the orbital surface of the lachrymal bone, and passing across the lachrymal sac, divides into two slips, which pass behind the lachrymal canals and become continuous with the margin of the orbicularis along the edges of the lids ; some few of its fibres being attached to the lachrymal canals as far as the puncta. Nerve-supply.—Infraorbital branch of facial. Actions.—The palpebral portion of the orbicularis acts involun- tarily in closing the lids, and from the greater curve of the upper lid, upon that principally. The entire muscle constitutes a sphincter, drawing at the same time, by means of its osseous attachment, the integument and lids inwards towards the nose. The corrugatores superciliorum draw the eyebrows downwards and inwards, and EXTRINSIC MUSCLES OF THE EAR. 233 produce the vertical wrinkles of the forehead. The tensor tarsi is an auxiliary to the orbicularis, and draws the extremities of the lachrymal canals inwards, so as to place the puncta in the best position for receiving the tears. It compresses the lachrymal sac, and serves also to keep the lids in relation with the surface of the eye. 3. Auricular Group.— Attollens auriculam, Attrahens auriculam, Retrahens auriculam. Dissection.—If the pinna of the ear he drawn down by means of a hook, a ridge of skin will rise up, extending from the ear to the cut edge of the scalp ; along this ridge an incision is to be made and the skin reflected downwards ; by this means the upper of the three muscles will be exposed. In like manner the pinna must be drawn backwards to expose the attrahens, and forwards to expose the retra- hens, the skin being removed by an incision close around the base of the ear, supplemented by others running in the course of the muscles. The muscles are best dissected by commencing with their tendons, and thence proceeding in the course of their radiating fibres. The ATTOLLENS AURICULAM, the largest of the three, is a thin fan-shaped plane of muscular fibres, arising from the lateral portion of the epicranial aponeurosis at about the middle of the temporal ridge, and inserted into the upper part of the concha and inner and upper part of the pinna. It is in relation by its external surface with the integument, and by the internal with the temporal fascia. Nerve-supply.—Temporal branches of facial. The ATTRAHENS AURICULAM arises from the lateral portion of the epicranial aponeurosis above the zygoma, and is inserted into the spine of the helix. It is often blended with the anterior edge of the former muscle. It is in relation by its external surface with the integument, and by the internal with the temporal fascia and temporal artery and veins. Nerve-supply.—Temporal branches of facial. The RETRAHENS AURICULAM arises by two (sometimes three) muscular slips from the root of the mastoid process. They are inserted into the posterior surface of the concha. It is in relation by its external surface with the integument, and by its internal surface with the mastoid portion of the temporal bone. Nerve-supply.—Posterior auricular branch of facial, and small occipital nerves. Actions.—The actions of the auricular muscles are expressed in their names ; they have but little power in man, but are important muscles in brutes. 234 ORBITAL MUSCLES. 4- Ocular Group. Levator palpebrae, Rectus superior, Rectus inferior, Rectus interims, Rectus externus, Obliquus superior, Obliquus inferior. Dissection.—To open the orhit (the calvarium and brain having been removed) the frontal bone must be sawn through at the inner extremity of the orbital ridge, the saw being directed to the supra- orbital notch ; and, externally, at its outer extremity. The roof of the orbit may then be comminuted with the hammer—a process easily accomplished, on account of the thinness of the orbital plate of the frontal bone and lesser wing of the sphenoid. The super- ciliary portion of the orbit may next be driven forwards by a smart blow, and the external angular process and external wall of the orbit outwards in the same manner ; the broken fragments of the roof of the orbit should then be removed. Remove the perios- teum from the whole of the upper surface of the exposed orbit, and examine the parts beneath. The LEVATOR PALPEBRiE SUPERIORIS is a long, thin, and triangular muscle situated at the upper part of the orbit in the middle line ; it arises from the under surface of the lesser wing of the sphenoid, above and in front of the optic foramen, and is inserted into the upper border of the superior tarsal plate by a broad but thin tendon. Relations.—By its upper surface with the fourth nerve, supra- orbital nerve and artery, periosteum of the orbit, and, in front, inner face of the broad tarsal ligament. By its under surface it rests on the superior rectus, globe of the eye, and conjunctiva; it receives its nerve and artery by this aspect. Nerve-supply.—Superior division of the third nerve. The RECTUS SUPERIOR arises from the upper margin of the optic foramen, and from the fibrous sheath of the optic nerve ; and is inserted into the upper surface of the globe of the eye at a point somewhat more than three lines from the margin of the cornea. Relations.—By its upper surface with the levator palpebrae muscle ; by the under surface with the optic nerve, ophthalmic artery and nasal nerve, and, in front, with the globe of the eye, the tendon of the superior oblique muscle being interposed. Nerve-supply.—Superior division of the third nerve. The RECTUS INFERIOR arises from the inferior margin of the optic foramen by a tendon (ligament of Zinn) which is common to it and the internal and external rectus, and from the fibrous sheath of the optic nerve ; it is inserted into the inferior surface of the globe of the eye, a little more than two lines from the margin of the cornea. Relations.—By its upper surface with the optic nerve, inferior branch of the third nerve, adipose tissue of the orbit., and under ORBITAL MUSCLES. 235 surface of the globe of the eye. By its under surface with the perios- teum of the floor of the orbit, and inferior oblique muscle. Nerve-supply.—Inferior division of the third nerve. The RECTUS INTERNUS, the thickest and shortest of the straight muscles, arises from the common tendon, and from the fibrous sheath of the optic nei've ; and is inserted into the inner surface of the globe of the eye at two lines from the margin of the cornea. Relations.—By its internal surface with the optic nerve, adipose tissue of the orbit and eyeball. By its outer surface with the perios- teum of the orbit; by its upper border with the anterior and pos- terior ethmoidal vessels, nasal and infra-trochlear nerves. Nerve-supply.—Inferior division of the third nerve. The RECTUS EXTERNUS, the longest of the straight muscles, arises by two heads, one with the origin of the superior rectus, from the margin of the optic fora- men ; the other partly from the common tendon, and partly from the lower margin of the sphenoidal fissure ; the nasal, third, and sixtli nerves and ophthalmic vein passing between them. It is inserted into the outer surface of the globe of the eye, a little more than two lines from the mar- gin of the cornea. Relations.—Bv its inter- nal surface with the third, nasal, sixth, and optic nerves, ciliary ganglion and nerves, ophthalmic artery and vein, adipose tissue of the orbit, inferior oblique muscle, ancl eyeball. By its external sur- face with the periosteum of the orbit and lachrymal gland ; by the upper border with the lachrymal vessels and nerve. Nerve-supply.—The sixth nerve. The recti muscles present several characters in common ; thus, they are thin, have each the form of an isosceles triangle, bear the same relation to the globe of the eye, and are inserted in a similar manner into the sclerotic, at about two lines from the circumference of the cornea. The points of difference relate to thickness and length ; the internal rectus is the thickest and shortest, the external the longest, and the superior the most thin. The insertion of the four recti into the globe of the eye forms a tendinous expansion, which is continued as far as the margin of the cornea, and is termed tunica albuginea. The OBLIQUUS SUPERIOR (trochlearis) is a fusiform muscle arising from the margin of the optic foramen, and from the fibrous Fig. 183.—Muscles of the eyeball; the view is taken from the outer side ofgthe right orbit. 1. Levator palpebrse. 2. Superior oblique. 3. Superior rectus. 4. Cut outer end of the external rectus. 5. The two heads of origin of the external rectus. 6. Optic nerve. 7. Internal rectus. 8. Inferior rectus. 9. Inferior oblique. CAPSULE OF TENON. sheath of the optic nerve ; it passes forward to the pulley at the internal angular process of the frontal bone ; its tendon is then reflected outwards beneath the superior rectus to the outer part of the globe of the eye, where it is inserted into the sclerotic coat, at about midway between the margin of the cornea and the optic nerve. The trochlea or pulley of the superior oblique muscle is a cartilaginous ring attached to the depression beneath the internal angular process of the frontal bone by bands of white fibrous tissue. The ring is flat, about a line in width, and provided with a synovial membrane, which is continued, together with a fibrous sheath, for a short dis- tance, upon the tendon. Sometimes the ring is supported, or in part formed, by a process of bone. Relations.—By its superior surface witli the fourth nerve, supra- trochlear nerve, superior rectus, and periosteum of the orbit. By the inferior surface with the adipose tissue of the orbit, globe of the eye, upper border of the internal rectus, and the vessels and nerves crossing that border. Nerve-supply.—The fourth nerve. The OBLIQUUS INFERIOR, a thin and narrow muscle, arises from the inner margin of the superior maxillary bone, immediately external to the lachrymal groove, and passes beneath the inferior rectus, to be inserted into the outer and posterior part of the eyeball, at about two lines from the entrance of the optic nerve. Relations.—By its superior surface with the inferior rectus muscle and eyeball ; by the inferior surface with the periosteum of the floor of the orbit, and external rectus. Nerve-supply.—Inferior division of the third nerve. CAPSULE OF TENON.—The muscles of the orbit are separated from the globe of the eyeball and structures immediately surround- ing the optic nerve, by a fascia, which is continuous with the broad tarsal ligament and tarsal cartilages. This fascia is termed tunica vaginalis oculi, or capsule of Tenon. It surrounds the eyeball except at the anterior part where it is reflected on the inside of the conjunctiva and eyelids, and is pierced anteriorly, for the passage of the six orbital muscles, by six openings, through which the tendons of the muscles play as through pulleys. Tubular pro- longations are continued on to the muscles as they pierce the capsule, but soon become lost in their sheaths. From this fascia processes pass off into the fat of the orbit, and divide the cavity into a number of loculi tilled with fat. The most important of these bands passes across the lower part of the orbit, and is attached to the malar and lachrymal bones ; it slings up the orbital contents, and hence has been called the suspensory ligament by Lockwood. Other bands pass from the malar and lachrymal bones to the sheaths around the external and internal recti muscles ; they serve to check the external and internal rotation of the eyeball, and have been named the external and internal check ligaments. The capsule of Tenon is a serous membrane and is lined with endothelium ; it consists of a parietal and visceral layer, and the ACTIONS OF THE ORBITAL MUSCLES. space between these forms a lymph-space which is continuous with the space between the inner and outer sheath of the optic nerve. Actions.—The levator palpebrse raises the upper eyelid. The four recti, acting singly, pull the eyeball in the four directions— upwards, downwards, inwards, and outwards. Acting by pairs, they carry the eyeball in the diagonal of these directions, viz., upwards and inwards, upwards and outwards, downwards and in- wards, downwards and outwards. Acting all together, they directly retract the globe within the orbit. The superior oblique muscle, acting alone, rolls the globe inwards and forwards, and carries the 237 Fig. 184.—Section of right orbit seen from the front, and showing orbital contents and capsule of Tenon. 1. Cristi galli. 2. Infundibulum. 3. Frontal sinus. 4. Superior meatus of nose. 5. Antrum of Highmore. 6. Supra-orbital vessels and nerve. 7. Levator palpebrae. 8. Superior rectus. 9. Internal rectus. 10. Inferior rectus. 11. Inferior oblique. 12. External rectus. 13. Lachrymal gland. 14. Temporal muscle. 15. Infra-orbital nerve, a. Cut edge of capsule of Tenon. 6. Optic nerve with small portion of sclerotic coat attached, c. Cavity for the eye- ball, formed by the capsule of Tenon. pupil outwards and downwards to the lower and outer angle of the orbit. The inferior oblique, acting alone, rolls the globe outwards and backwards, and carries the pupil outwards and upwards to the tipper and outer angle of the eye. The superior rectus when acting alone tends not only to raise the eyeball, but also to carry it inwards, and rotate it slightly on its own axis ; this tendency to inversion and rotation is corrected by the combination of that muscle with the inferior oblique, the latter tending to direct the pupil outwards and to rotate the ball in the opposite direction to the rectus. In like manner the inferior rectus and superior oblique are combined in 238 ACTION OF ORBITAL MUSCLES. their action, the oblique muscle correcting the tendency of the rectus to carry the eyeball inwards, and to rotate the ball on its own axis. In all oblique movements of direction there is a combination of two recti with one oblique muscle ; the actions performed by the several muscles, and the way in which they are associated, are well shown in the subjoined table taken from Beaunis’ work :— Number of Muscles in Activity. Direction of Line of Regard. Muscles Acting. One . ( Inwards . ( Outwards Internal rectus. External rectus. Two . J Upwards. f Superior rectus. j Inferior oblique. 1 Downwards j Inferior rectus. \ Superior oblique. 'Inwards and wards . Up- i Internal rectus. < Superior rectus. (Inferior oblique. Inwards and Down- f Internal rectus. < Inferior rectus. Three warns . ( Superior oblique. • -< Outwards and Up- f External rectus. -J Superior rectus. (Inferior oblique. Outwards and Down- ( External rectus. < Inferior rectus. ( Superior oblique. wards . V. 5. Nasal Group. Pyramidalis nasi, Compressor nasi, Dilatator naris. Depressor alao nasi, Dissection.—The incision already made down the centre of the nose is to he continued round the margin of the ala to the lower edge of the septum, from thence down the middle of the upper lip to its free margin ; from this point it should he carried round the mouth to the middle of the lower lip, and from thence vertically downwards to the chin. The whole of the Hap must now he care- fully dissected hack, care being taken to keep the knife very close to the inner surface of the skin. The PYRAMIDALIS NASI is a small pyramidal slip of muscular fibres sent downwards on the bridge of the nose by the occipito- frontalis. It becomes tendinous and is inserted into the tendinous expansion of the compressor nasi. Relations.—By its upper surface with the integument; by its under surface with the periosteum of the fronbil and nasal bone. Its outer border corresponds with the edge of the orbicularis palpebrarum : its inner border with its fellow, from which it is separated by a narrow areolar interval. Nerve-supply.—Infraorbital branch of facial MUSCLES OF NOSE. 239 The COMPRESSOR NASI is a thin and triangular muscle ; it arises by its apex from the canine ridge of the superior maxillary hone, and spreads out upon the side of the nose into a thin tendinous expansion, which is continuous across the ridge with the muscle of the opposite side, and above with the tendon of the pyramidalis nasi. It is connected at its origin with a muscular fasciculus which is attached to the nasal process of the superior maxillary bone im- mediately below the origin of the levator labii superioris alteque nasi. This muscular slip was termed by Albinus, musculus anomalus, from its attachment to bone by both ends. Relations.—By its superficial sur- face with the levator labii superioris proprius, levator labii superioris alseque nasi, and integument; by its deep surface with the superior maxil- lary and nasal bones, and with the alar and lateral cartilages of the nose. Nerve - supply.—Infraorbital branch of facial. The DILATATOR NARIS is a thin and indistinct muscular apparatus ex- panded on the ala of the nostril, and consisting of an anterior and poste- rior slip. The anterior slip (levator proprius alse nasi anterior) arises from the upper border and surface of the alar cartilage, and is inserted into the integument of the border of the nostril. The posterior slip (leva- tor proprius alse nasi posterior) arises from the nasal process of the superior maxillary bone and sesamoid cartilages, and is inserted into the posterior half of the integument of the border of the nostril. These muscles are difficult of dissection, from the close adhesion of the integument to the nasal cartilages. Nerve-supply.—Infraorbital branch of facial. The DEPRESSOR ANASI (depressor labii superioris alu3que nasi) is brought into view by drawing upwards the upper lip and raising the mucous membrane. It arises from the incisive fossa of the superior maxillary bone, and passes upwards and inwards to be inserted into the posterior part of the columna and ala nasi. It is closely connected with the deep surface of the orbicularis. Relations.— By its superficial surface with the mucous membrane Fic,. 185.—Muscles of the nose. 1 . Pyramidalis nasi. 2. Upper part of the levator labii superioris alae- que nasi turned aside. 3. Com- pressor nasi. 4. Musculus ano- malus. 5. Levator proprius alae nasi anterior. 6. Levator proprius alae nasi posterior. 7. Part of the depressor alae nasi. 8. Upper seg- ment of the orbicularis oris. 9. Naso-labialis. 10. Accessory slips of the orbicularis. 240 ORBICULARIS ORIS. of the mouth, orbicularis oris, and levator labii superioris alaeque nasi; by its deep surface with the superior maxillary bone. Nerve-supply.—Infraorbital branch of facial. Actions.—The pyramidal is nasi, as a point of attachment of the occipito-frontalis, assists that muscle in its action : it also draws down the inner angle of the eyebrow and produces short horizontal wrinkles across the root of the nose. By its insertion it fixes the aponeurosis of the compressores nasi, and tends to elevate the nose. The compressores nasi appear to act in expanding rather than com- pressing the nares. The dilatator naris is a dilator of the nostril, and the depressor alae nasi draws downwards both the ala and columna of the nose, the depression of the latter being assisted by the naso-labialis. 6. Superior Labial Group.— Orbicularis oris, Levator labii superioris alaeque nasi, Levator labii superioris proprius, Levator anguli oris, Zygomaticus major, Zygomaticus minor. Dissection.—The skin has been already removed in order to display the preceding group, but it is necessary now to put a hook in the angle of the mouth and carry it downwards, so as to keep the muscles of the upper lip on the stretch during the removal of the muscular fascia. The ORBICULARIS ORIS is a sphincter muscle, completely sur- rounding the mouth, and possessing consequently neither origin nor insertion. The upper part is attached by means of a small muscular fasciculus (naso-labialis) to the columna of the nose. It is divisible into two portions, internal or marginal, in immediate contact with the lips, and thick ; and external, broad and thin ; the separation between the two being indicated by the coronary arteries. The internal fibres are continued uninterruptedly from one lip to the other round the angle of the mouth, the external fibres decussate with those of the buccinator, the upper fibres of the orbicularis being continued into the lower ones of the latter muscle, and vice versa. Accessory fibres spring from the incisive fossa of the upper and lower jaw, and pass to the dee]) aspect of the muscle. In addition to the buccinator its fibres intermingle with those of the levator labii superioris proprius, levator labii superioris a he* pie nasi, depressor labii superioris alaeque nasi, levator anguli oris, zygomaticus major, risorius Santorini, depressor anguli oris, depressor labii in- ferioris, and levator labii inferioris. Relations.—By its superficial surface with the integument of the lips, with which it is closely connected. By its deep surface with the mucous membrane of the mouth, the labial glands and coronary arteries being interposed. By its circumference with the numerous muscles which move the lips, and by the inner border with the mucous membrane of the margin of the mouth. Nerve-supply.—Infraorbital and buccal branches of the facial. MUSCLES OF THE FACE. 241 The LEVATOR LABII SUPERIORIS ALiEQUE NASI is a thin triangular muscle ; it arises from the upper part of the nasal process of the superior maxillary bone, and, becoming broader as it descends, is inserted by two portions, one into the ala of the nose, the other into the orbicularis oris and upper lip. Relations.—By its superficial surface with the orbicularis palpe- brarum, facial artery, and integument. By its deep surface with the superior maxillary bone, musculus anomalus, compressor nasi, dilatator naris, and alar cartilage. Nerve-supply.—Infraorbital branch of facial. The LEVATOR LABII SUPERIORIS PROPRIUS is a thin quad- rilateral muscle; it arises from the lower border of the orbit, immediately above the infraorbital foramen, and passing obliquely downwards and inwards, is inserted into the integument of the upper lip, its deep fibres being blended with those of the orbicularis. Relations.—By its superficial surface with the lower .segment of the orbicularis palpebrarum, facial artery, and integument. By its deep surface with the compressor nasi, levator anguli oris, orbicularis oris, and infraorbital artery and nerve. Nerve-supply.—Infraorbital branch of facial. The LEVATOR ANGULI ORIS arises from the canine fossa of the superior maxillary bone, and passes obliquely downwards and outwards to be inserted into the angle of the mouth ; its HI)res being continued into the orbicularis and depressor anguli oris. Relations.—Bv its superficial surface with the levator labii superioris proprius, branches of the infraorbital artery and nerve, and interiorly with the integument. By its deep surface with the superior maxillary bone and buccinator muscle. Nerve-supply.—Infraorbital branch of facial. The ZYGOMATIC muscles are two slender fasciculi of fibres which arise from the malar bone, and are inserted into the upper lip. The zygomaticus major descends to the angle of the mouth, and is continuous with the inferior segment of the orbicularis, depressor anguli oris, and risorius Santorini. The zygomaticus minor, lying in front of the major, becomes connected with the outer border of the levator labii superioris proprius, and is attached to the integument of the upper lip. This muscle is in reality only a detached slip of the orbicularis palpebrarum. Relations.—The zygomaticus major is in relation by its super- ficial surface with the lower segment of the orbicularis palpebrarum above, and with the fat of the cheek and integument for the rest of its extent. By its deep surface with the malar bone, masseter, buccinator, and facial vessels. Nerve-supply.—Infraorbital branch of facial. Actions.—The orbicularis oris produces the direct closure of the lips by means of its continuity, at the angles of the mouth, with the fibres of the buccinator. When acting singly in the forcible closure of the mouth, the integument is thrown into wrinkles, in consequence of its firm connection with the surface of the muscle ; its naso-labial MUSCLES OF THE FACE. 242 fasciculus draws downwards the columna nasi. The levator labii superioris alaeque nasi lifts the upper lip with the ala of the nose, and expands the opening of the nares. The levator labii superioris proprius is the proper elevator of the upper lip : acting singly, it draws the lip a little to one side. The levator proprius, and still more the levator ala3 nasi, is brought into play in the expression of contempt or derision. The levator anguli oris lifts the angle of the mouth and draws it inwards, while the zygomatici pull it upwards and outwards, as in laughing, and produce the dimple in the cheek. In the movement of laughter the zygomatici are assisted by the risorius Santorini. 7. Inferior Labial Group.— Depressor labii inferioris, Depressor anguli oris, Risorius Santorini, Levator labii inferioris. Dissection.—To dissect the inferior labial region, continue the incision already made along the margin of the lower jaw to its angle. Dissect off the integument and superficial fascia from this surface, and the muscles of the inferior labial region will be exposed. The DEPRESSOR LABII INFERIORIS (quadratics menti) arises from the oblique line by the side of the symphysis of the lower jaw, and passing upwards and inwards, is inserted into the orbicularis muscle and integument of the lower lip. Its inner fibres interlace with those of the opposite muscle ; the outer fibres reach nearly to the angle of the mouth. This muscle is very thin, and pale in colour, and its fibres are mixed with a considerable quantity of fat, so that it is very difficult to make a good dissection of it. Relations.—Bv its superficial surface with the platysma myoides, part of the depressor anguli oris, and the integument of the chin with which it is closely connected. By the deep surface with the levator labii inferioris, labial glands, mucous membrane of the lower lip, and mental nerve and artery. Nerve-supply.—Supra-maxillary of facial. The DEPRESSOR ANGULI ORIS {triangularis oris) is a trian- gular plane of muscle arising by a broad base from the external oblique ridge of the lower jaw just below the mental foramen, and inserted by its apex into the angle of the mouth, where it is continu- ous with the levator anguli oris, zygomaticus major, and upper segment of the orbicularis. Near its insertion it is joined by the following muscle. Relations.—By its superficial surface with the integument; by its deep surface with the depressor labii inferioris, Imccinator, and branches of the mental nerve and artery. • Nerve-supply.—Supra-maxillary of facial. The RISORIUS SANTORINI is a triangular muscle, partly-formed by the continuation above the jaw of fibres of the platysma myoides, and partly of scattered and thin fibres arising from the fascia over the masseter and buccinator. It converges to the angle of the mouth MUSCLES OF MASTICATION. where it becomes connected with the outer border of the depressor anguli oris and zygomaticus major. Nerve-supply.—Supra-maxiilary of facial. The LEVATOR LABII INFERIORIS (levator menti) is to be dis- sected by everting the lower lip and raising the mucous membrane. It is a short but strong muscle arising from the incisive fossa of the lower jaw, and inserted into the integument of the chin. It is in relation with the mucous membrane of the mouth, with its fellow, and with the depressor labii inferioris. Nerve-supply.—Supra-maxiilary of facial. The whole of the muscles of the face have attachments to the integu- ments, as well as to each other and to the bones, and it is chiefly in consequenceof the integumentary attachments that they act as muscles of expression, for it is by this means that the ridges and furrows which give such characteristic expressions to the face are produced. Actions.—The depressor labii inferioris draws the lower lip down- wards, and a little outwards. The depressor anguli oris, from the radiated direction of its fibres, will pull the angle of the mouth either downwards and forwards, or downwards and backwards, and be expressive of grief ; or acting with the levator anguli oris, zygo- maticus major, and risorius Santorini, will draw the angle of the mouth upwards and backwards, or directly backwards. The levator labii inferioris raises and protrudes the integument of the chin. 8. Maxillary Group.— 243 Masseter, Temporal, Buccinator, Pterygoideus externus, Pterygoideus interims. Dissection.—The tiap already obtained must, be carried as far back as the posterior margin of the ramus of the jaw, and the struc- tures which cover the masseter must be cut away. Fascia.—The masseter muscle is covered by a strong layer of fascia continued on to it from the surface of the parotid gland (parotideo-masseteric fascia); below, it may be traced into the neck, where it is found to be continuous with the anterior layer of the deep cervical fascia. It is intimately connected with the tendinous fibres of the muscle, and is attached above to the lower border of the zygomatic arch. The MASSETER (pacrcraopai, to chew) is a short, thick, and some- what quadrilateral muscle, composed of two planes of fibres, super- ficial and deep. The superficial layer arises by a strong aponeurosis from the malar process of the superior maxillary bone and lower border of the malar bone, and passes downwards and backwards to be inserted into the ramus and angle of the inferior maxilla. The deep layer arises from the lower border of the malar bone and zygo- matic process of the temporal, and passes downwards and forwards to be inserted into the upper half of the ramus. Relations.—By its external surface with the zygomaticus major, risorius Santorini and platysma invoides, parotid gland and Stenson’s 244 MUSCLES OF MASTICATION duct, transverse facial artery, pes anserinus, and integument. By its internal surface with the temporal muscle, buccinator, from which it is separated by a mass of fat, and ramus of the lower jaw. By its posterior border with the parotid gland ; by the anterior border with the facial artery and vein. Nerve-supply.—Masseteric branch of the inferior maxillary of the fifth cerebral nerve. Fascia.—The strong aponeurotic layer which covers the temporal muscle is called the temporal fascia or aponeurosis ; it is attached above to the posterior border of the malar bone and the upper temporal crest on the frontal, parietal, and temporal bones. Below it separates into two layers, between which there is a small quantity of fat, a small nerve derived from the orbital branch of the superior maxil- lary nerve, and the orbital branch of the temporal artery. Of these two layers one is attached to the outer, and the other to the inner surface of the zygoma. Dissection.—Make an incision along the upper border of the zygoma, for the purpose of separating the temporal fascia from its attachment. Then saw through the zygomatic process of the malar bone, and through the root of the zygoma near 1 lie meatus auditorius. 1 )raw down the zygoma, and with it the origin of the masseter, and dissect the latter muscle away from the ramus and angle of the inferior maxilla. Now remove the temporal fascia from the rest of its attachment, and the whole of the temporal muscle will be brought into view. The TEMPORAL is a broad and radiating muscle, occupying a considerable extent of the side of the head, and filling the temporal fossa. It arises by tendinous fibres from the whole length of the inferior temporal crest, and by muscular fibres from the temporal fascia and entire surface of the temporal fossa, excepting the anterior or malar wall. Its fibres converge to a strong and narrow tendon, which is inserted into the apex, internal surface, and anterior border of the coronoid process of the lower jaw, as far down as the junction of the body and ramus. Relations.—Bv its external surface with the temporal fascia (which separates it from the attollens and attrahens auriculam muscles, and temporal vessels and nerves) and with the zygoma and masseter. By its internal surface with the bones forming the temporal fossa, the external pterygoid muscle, part of the buccinator, and the internal maxillary artery with its deep temporal branches. Nerve-supply.—Temporal branches of the inferior maxillary of the fifth cerebral nerve. Dissection.—Saw through the ramus of the lower jaw a little above the level of the crowns of the lower molar teeth, then divide the neck of the condyle with saw and bone-forceps. Now turn up the coronoid process and portion of ramus thus detached, together with the temporal muscle (which may be dissected from the fossa), and a view of the entire extent of the buccinator and external ptery- goid muscles will be obtained. MUSCLES OF MASTICATION. The BUCCINATOR (buccinu, a trumpet), the trumpeter’s muscle, arises from the base of the alveolar processes of the superior and in- ferior maxillary bones, corresponding to the three molar teeth, and the pterygo-maxillary ligament. This ligament is the raphe of union between the buccinator and superior constrictor muscles, and is attached by one extremity to the hamular process of the internal pterygoid plate, and by the other to the extremity of the molar ridge of the lower jaw. The fibres of the muscle converge towards the angle of the mouth, where some are continuous with the levator and depressor anguli oris, and the greater number cross each other, the superior being continuous with the inferior segment of the orbicularis oris, the inferior with the superior segment. The fibres along the upper border of the muscle pass directly into the upper fibres of the orbicularis and do not decussate, and those along the lower border in like manner pass directly into the lower fibres of that muscle. The muscle is invested externally by a thin fascia (buccal) which extends backwards to the pharynx. Relations.—By its external surface, posteriorly, with a large and rounded mass of fat, which separates the muscle from the ramus of the lower jaw, temporal, and masseter : anteriorly with the risorius Santorini, zygomatici, levator anguli oris, and depressor anguli oris. It is also in relation with a part of Stenson’s duct (which pierces it opposite the second molar tooth of the upper jaw), with the trans- verse facial artery, branches of the facial and buccal nerves, and facial and buccal arteries and veins. By its internal surface with the buccal glands and mucous membrane of the mouth. Nerve-supply.—Buccal branch of facial, which supplies it on its superficial surface. The PTERYGOIDEUS EXTERNUS is a short and thick muscle, broader at its origin than at its insertion. It arises by two heads, one from the pterygoid ridge on the under surface of the great wing of the sphenoid ; the other from the outer surface of the external pterygoid plate, tuberosity of the palate bone and tuberosity of the superior maxillary. The fibres pass backwards to be inserted into a depression on the anterior aspect of the neck of the lower jaw, and into the interarticular fibro-cartilage. The internal maxillary artery passes between the two heads of this muscle, and the lower head is commonly pierced by the buccal branch of the fifth nerve. Relations.—By its external surface with the'ramus of the lower jaw, temporal muscle, and internal maxillary artery ; by its internal surface with the internal pterygoid muscle, internal lateral liga- ment of the jaw, middle meningeal artery, and inferior maxillary nerve ; by its upper border with the muscular branches of the inferior maxillary nerve. Nerve-supply.—Buccal branch of inferior maxillary. Dissection.—The condyle of the jaw must now be removed from its socket, and, together with the external pterygoid, be turned over towards the nose, so as to expose the internal pterygoid. The PTERYGOIDEUS INTERNUS is a thick quadrangular muscle 245 246 ACTIONS OF THE MUSCLES OF MASTICATION. It arises from the pterygoid fossa, being attached to the inner sur- face of the externa] pterygoid plate, and that part of the tuberosity of the palate bone which is interposed between the pterygoid plates ; it also gets an additional origin from the angle between the outer surface of the external pterygoid plate and the tuberosity of the superior maxillary bone. It de- scends obliquely backwards, to be inserted into the inner surface of the angle of the lower jaw. It resembles the masseter in appear- ance and direction, and was named by Winslow internal 'masseter. Relations. — By its external surface with the external ptery- goid, inferior maxillary nerve and branches, internal maxillary artery and branches, internal lateral ligament, and ramus of the lower jaw. By its internal surface with the tensor palati, superior constrictor and fascia of the pharynx ; by its posterior border with the parotid gland. Nerve-supply.—Pterygoid branch of inferior maxillary. Actions.—The maxillary muscles are the active agents in masti- cation, and form an apparatus admirably fitted for that office. The buccinator circumscribes the cavity of the mouth, and with the aid of the tongue keeps the food under the immediate pressure of the teeth. By means of its connection with the superior constrictor, it shortens the cavity of the pharynx from before backwards, and becomes an auxiliary in deglutition. The temporal, the masseter, and the internal pterygoid are the bruising muscles, drawing the lower jaw against the upper with great force. The two latter, from the obliquity of their direction, assist the external pterygoid in grind- ing the food, by carrying the lower jaw forward upon the upper; the jaw being brought back again by the deep portion of the masseter and posterior fibres of t he temporal. The external pterygoid muscles, when both act together, draw the jaw forwards, but more frequently they act alternately, each drawing the jaw forwards and towards the opposite side, so as to produce by their alternate action the grinding movements of the molar teeth. The internal pterygoid assists the external muscle of the same side in protracting the jaw, and throw- ing the teeth towards the opposite side. The temporal is the only muscle of mastication which retracts the jaw ; all the rest protract it. The whole of these muscles, acting in succession, produce a rotatory movement of the teeth upon each other, which, with the direct action of the lower jaw against the upper, effects the mastication of the food. Fig. 186.—The two pterygoid muscles. The zygomatic arch and the greater part of the ramus of the lower jaw have been removed in order to bring these muscles into view. i. The sphenoid head of the external pterygoid. 2. Its pterygoid head. 3. The internal ptery- goid. MUSCLES AND FASCIA] OF THE NECK. 247 MUSCLES AND FASCIvE OF THE NECK. The muscles of the neck may he arranged into eight groups, cor- responding with the natural divisions of the region ; they are :— 1. Superficial group. 2. Depressors of the os hyoides and larynx. 3. Elevators of the os hyoides and larynx. 4. Lingual group. 5. Pharyngeal group. 6. Palatine group. 7. Prsevertebral group. 8. Laryngeal group. Superficial Group.— Platysma myoides. Sterno-cleido mastoid. Dissection.—The dissection of the neck should be commenced by making an incision along the middle line of its fore-part from the chin to the sternum, and bounding it superiorly and interiorly by two transverse incisions; the superior being carried along the margin of the lower jaw, and across the mastoid process to the pro- tuberance on the occipital bone, the inferior along the clavicle to the acromion process. The square flap of integument thus included should be turned back from the entire side of the neck, which brings into view the superficial fascia, and on the removal of a thin layer of this the platysma myoides will be exposed. The superficial cervical fascia is a part of the common super- ficial fascia of the entire body, and is only interesting from contain- ing between its layers the platysma mvoides muscle'. The PLATYSMA MYOIDES (ttXcitvs pis eldos, broad muscle-like lamella) is a thin plane of muscular fibres, situated beneath the integument on the side of the neck. It arises from the fascia over the pectoralis major and deltoid muscle, and from the clavicle and acromion ; it passes obliquely upwards and inwards to be inserted into the side of the chin, oblique line of the lower jaw, angle of the mouth, and integument of the face. The anterior fibres mingle beneath the chin with those of the muscle of the opposite side ; the next interlace with the depressor anguli oris and depressor labii inferioris ; the posterior fibres are disposed in a transverse direction across the lower part of the face, arising from the fascia over the parotid gland and masseter muscle, and inserted into the angle of the mouth, where they form part of the risorius Santorini muscle. The entire muscle is analogous to the cutaneous muscle of brutes, the panniculus carnosus. Relations.—By its external surface with the integument, with which it is closely adherent below, but loosely above. Bv its DEEP CERVICAL FASCIA. 248 internal surface, below the clavicle, with the pectoral is major and deltoid ; in the neck with the trapezius, sterno-mastoid, external jugular vein and deep cervical faseia ; on the face, with the parotid gland, masseter, facial artery and vein, buccinator, depressor anguli oris, and depressor labii inferioris. Nerve-supply.—Its upper part by the facial, its lower by the superficial cervical. Dissection.—The platysma is now to be removed, commencing in front and turning it backwards towards the spine ; great care must lie taken not to cut the branches of the superficial cervical plexus, or the external jugular vein which lies beneath it. The deep cervical fascia will now be exposed, and must be carefully studied. The deep cervical fascia is a strong areolo-fibrous membrane, which invests the muscles of the neck, and retains and supports the vessels and nerves. It commences posteriorly at the ligamentum nuchae, and passes forwards at each side beneath the trapezius Fig. 187.—Transverse section of the neck, showing the deep cervical fascia and its prolongations forming sheaths for the muscles. 1. Platysma myoides. 2. Trapezius. 3. Liga- mentum nuchae. 4. The point at which the fascia divides to form the sheath for the sterno-mastoid (5). 6. The point of reunion of the two layers. 7. The point of union of the fascia of opposite sides of the neck. 8. Sterno-hyoid. 9. Omo- hyoid. 10. Sterno-tliyroid. 11. Lateral lobe of the thyroid gland. 12. Trachea. 33. (Esophagus. 14. Carotid sheath. 15. Longus colli. The nerve in front of the sheath of this muscle is the sympathetic. 16. Rectus anticus major. 17. Scalenus anticus. 18. Scalenus inedius. 19. Splcnius capi- tis. 20. Splenius colli. 21. Levator anguli scapulas. 22. Complexus. 23. Trachelo-mastoid. 24. Trausver- ■salis cervicis. 25. Cervicalis ascen- dens. 26. Semi-spinalis colli. 27. Multifidus spitne. 28. Cervical yertebra. muscle to the posterior border of the sterno-mastoid ; here it divides into two layers, which embrace that muscle and unite upon its anterior border to be prolonged onwards to the middle line of the neck, where it is continuous with the fascia of the opposite side. Besides constituting a sheath for the sterno-mastoid, it also forms sheaths for the other muscles of the neck over which it passes. If the superficial layer (anterior layer) of the sheath of the sterno- mastoid be traced upwards, it will be found to pass over the parotid gland and masseter muscle (fascia parotideo-masseterica), to be in- serted into the zygomatic arch ; traced downwards, it will be seen to pass to the front of the clavicle, to which it becomes attached. If the deep layer (posterior layer) of the sheath be examined supe- STERNO-CLEIDO MASTOID. 249 riorly, it will be found attached to the styloid process, from which it is reflected to the angle of the lower jaw, forming the stylo-maxil- lary ligament; followed downwards, a process of it will be found connected with the tendon of the omo-hyoid muscle, binding it down to the clavicle, while still lower it becomes continuous with the costo-coracoid membrane. It is pierced in the posterior triangle of the neck by the external jugular vein. In the middle line the deep cervical fascia is thin above where it becomes attached to the hyoid bone, but as it descends it becomes thicker and splits into two layers, a superficial and a deep, between which there is a little fat and areolar tissue, as well as a lymphatic gland. The superficial of these layers is attached to the anterior edge of the sterno-mastoid, and below to the sternum and inter-clavicular ligament; the deep layer is intimately connected with the sterno-hyoid and sterno- thyroid, ensheathing them, and becoming attached to the posterior surface of the sternum. Still deeper in the anterior triangle, a thin sheet of fascia passes behind the depressor muscles of the hyoid to invest the thyroid body, and being continued on to the trachea may be traced to the fibrous layer of the pericardium, with which it blends. The deep cervical fascia also forms a sheath for the common carotid artery, internal jugular vein, and pneumogastric nerve, a fibrous septum intervening between the artery and vein. That portion of the fascia which covers the muscles lying on the front of the vertebral column, and intervenes between them and the pharynx and oesophagus, is called the pre-vertebral fascia. Dissection.—Remove the deep cervical fascia and expose the sterno-mastoid muscle. The STERNO-CLEIDO MASTOID is the large oblique muscle of the neck, and is situated between two layers of the deep cervical fascia. It arises, as implied by its name, from the sternum and clavicle («XeiStov), and passes obliquely upwards and backwards, to be inserted into the mastoid process of the temporal, and superior curved line of the occipital bone. The sternal portion arises by a rounded tendon, increases in breadth as it ascends, and spreads out to a considerable extent at its insertion. The clavicular portion is broad and fleshy, separate from the sternal portion below, but blended with the posterior surface of the latter as it ascends. The two portions of this muscle are sometimes described as separate muscles under the names of sterno-mastoid and cleido-mastoid, these being again occasionally subdivided, the first into sterno-mastoid and sterno-occipital, and the second into cleido-mastoid and deido-occipital. The cleido-mastoid is the most deeply seated slip of the muscle, and has a separate attachment to the mastoid process ; it is generally perforated by the spinal accessory nerve. Relations.—By its superficial surface with the integument, pla- tysma myoides, external jugular vein, superficial branches of the cervical plexus of nerves, and anterior layer of the deep cervical fascia. By its deep surface with the deep layer of the cervical fascia, sterno-clavicular articulation, sterno-hyoid, sterno-thyroid, omo- ACTIONS OF STERNO-MASTOID AND PLATYSMA. 250 hyoid, scaleni, levator anguli scapula;, splenii, and posterior belly of the digastricus muscle ; phrenic nerve, transversal is colli, and supra- scapular artery ; deep lymphatic glands, sheath of the common caro- tid and internal jugular vein, descendens cervicis nerve, external carotid artery with its posterior branches, and commencement of the internal carotid artery ; cervical plexus of nerves, pneumogastric, spinal accessory, hypoglossal, sympathetic, and facial nerves, and parotid gland. It is pierced on this aspect by the spinal accessory nerve. Nerve-supply.—Spinal accessory nerve, and branches of the second and third cervical nerves. Actions.—The platysma produces a muscular traction on the ntegument of the neck, which prevents it from falling so flaccid in Fig. t88. — Muscles of the anterior aspect of the neck; on the right side of the figure the superficial muscles are seen, on the left the deep. i. Posterior belly of digastricus. 2. Its anterior belly. Aponeurotic pulley, through which its ten- don is seen passing, attached to the body of the os hyoides. 3, 4. Stylo - hyoid muscle transfixed by the posterior belly of the digastricus. 5. Mylo-liyoid. 6. Genio- hyoid. 7. Thetongue. 8. Hyo - glossus. 9. Stylo - glossus. 10. Stylo-pharyngeus. 11. Sterno-mastoid. 12. Its sternal origin. 13. Its clavicular origin. 14. Sterno-hyoid. 15. Sterno-thyroid of the right side. 16. Thyro- hyoid. 17. Hyoid por- tion of the omo-hyoid. 18, 18. Its scapular portion ; on the left side, the tendon of the muscle is seen to be bound down by a portion of the deep cervical fascia. 19. Clavicular portion of the trapezius. 20. Scalenus anticus, of the right side. 21. Scalenus posticus ; the scalenus medius is seen between the two. old persons as it would if the extension of the skin were the mere result of elasticity. It draws also on the angle of the mouth, and is one of the depressors of the lower jaw. It assists in the expres- sion of the emotion of fright or extreme fear. The sterno-mastoid muscles (nutatores capitis) are the great anterior muscles of con- nection between the thorax and the head. Both muscles acting together, when the spine is fixed, raise the head and carry it back- wards. The clavicular portions, acting more forcibly than the sternal, give stability and steadiness to the head in supporting weights. Either muscle acting singly would draw the head towards TRIANGLES OF THE NECK. 251 the shoulder of the same side, and carry the face towards the oppo- site side. If the head be fixed, they can raise the sternum in forced inspiration. Regional Anatomy of the Neck. The region of the neck is divided into two great triangles by the sterno-mastoid muscle. The posterior triangle is bounded by the posterior border of the muscle, by the clavicle, and by the anterior edge of the trapezius. The anterior triangle is bounded by the anterior border of the sterno-mastoid, by the lower border of the inferior maxilla, and a line drawn from the angle of this bone to the mastoid process, and by the mesial line. The posterior triangle is subdivided into two by the scapular belly of the omo-hyoid muscle. The posterior superior triangle (occi- pital triangle) is bounded by the posterior border of the sterno-mas- toid, the anterior edge of the trapezius, and the posterior belly of the omo-hyoid. Its floor is formed from above downwards by the splenius capitis, levator anguli scapulae, scalenus posticus, scalenus medius, and upper digitation of the serratus magnus muscles. It contains the superficial descending branches of the cervical plexus, the spinal accessory nerve, the transversalis colli artery and vein, the super- ficialis colli artery, and the cervical lymphatics and glands. The posterior inferior or subclavian triangle is bounded by the clavicle, the posterior belly of the omo-hyoid, and the posterior border of the sterno-mastoid. This triangle contains the third part of the subclavian artery, above and behind which are the trunks of the brachial plexus ; below, and in front of it, almost overlapped by the clavicle, the subclavian vein, in close proximity to which, behind the clavicle, is the suprascapular artery, both of which vessels, although not strictly in the triangle, are apt. to invade it as soon as the fascia is divided in the operation for ligature of the subclavian. The external jugular vein terminates in the sub- clavian vein about the middle of this space; near its termination it receives the transversalis colli and suprascapular veins. This triangle also contains a small nerve to the subclavius muscle and a lymphatic gland. The anterior triangle has been divided into three—the inferior carotid, the superior carotid, and the submaxillary. The inferior carotid triangle is bounded by the mesial line, the anterior border of the sterno-mastoid, and the anterior belly of the omo-hyoid. Its floor is formed by the longus colli muscle and vertebral column, and its roof by the integument, superficial fascia, platysma myoides, and deep cervical fascia. It contains the sterno- hyoid and sterno-thyroid muscles, common carotid artery, internal jugular vein, inferior thyroid artery, superior thyroid artery, thyroid body, lower part of larynx, trachea, lower part of pharynx, oeso- phagus, recurrent laryngeal nerve, descendens and communicans cervicis nerves, sympathetic nerves, inferior thyroid veins, and one or two lymphatic glands. DEPRESSORS OF THE HYOID BONE AND LARYNX. The superior carotid triangle (the place of selection for ligature of the carotid artery) is bounded by the anterior border of the sterno-mastoid, the anterior belly of the omo-liyoid, and the pos- terior belly of the digastricus. Its floor is formed by parts of the thyro-hyoid, hyo-glossus, and middle and inferior constrictor muscles, and its roof by the integument, superficial fascia, platysma, and deep fascia. It contains the common, external and internal carotid arteries, the superior thyroid, lingual, facial, occipital, and ascending pharyngeal arteries ; the superior thyroid, lingual, facial, ascending pharyngeal and internal jugular veins ; the hypoglossal, vagus, spinal accessory, descendens cervicis, superior laryngeal and sympathetic nerves ; the upper part of larynx and lower part of pharynx ; some lymphatic vessels and glands. The submaxiliary triangle is bounded above by the lower border of the body of the lower jaw, the parotid gland and mastoid process, below by the posterior belly of the digastricus and the stylo-hyoid, in front by the mesial line. Its floor is formed by the anterior belly of the digastricus, the mylo-hyoid and hyo-glossus muscles. The space contains the submaxiliary gland, facial artery and vein, sub- mental artery, mylo-hyoid artery and nerve, external carotid artery, part of the parotid gland, internal carotid artery, commencement of external and interior jugular veins, pneumogastric and glosso- pharyngeal nerves, and submaxiliary lymphatic vessels and glands. Second Group.—Depressors of the Os Hyoides and Larynx. Sterno-hyoid, Sterno-thyroid, Thyrohyoid, Omo-hvoid. Dissection.—These muscles are brought into view by removing the deep fascia from the front of the neck between the two sterno- mastoid muscles. The omo-hyoid to be seen in its whole extent requires that the sterno-mastoid muscle be divided from its origin and turned aside. The STERNO-HYOID is a narrow ribbon-like muscle, arising from the posterior surface of the first bone of the sternum and from the inner extremity of the clavicle. It is inserted into the lower border of the body of the hyoid bone. Relations.—By its superficial surface with the sternum, sternal end of clavicle, deep cervical fascia, platysma myoides and sterno- mastoid muscle ; by its deep surface with the sterno-thyroid, crico- thyroid, and thyro-hvoid muscles, superior thyroid artery, thyroid gland, crico-thvroid and thyro-hyoid membranes. Nerve-supply.—Descendens cervicis. The STERNO-THYROID, broader than the preceding, beneath which it lies, arises from the posterior surface of the upper bone of the sternum, and from the cartilage of the first rib ; it is inserted into the oblique line on the great ala of the thyroid cartilage. The inner DEPRESSORS OF THE HYOID ROME AND LARYNX. borders lie in contact along the middle line, and the muscles are sometimes marked by a tendinous intersection at their lower part. Some of the fibres of this muscle are continued directly into the thyro-hyoid without intervening attachment; others are continuous with the inferior constrictor. Relations.—By its external surface with the sterno-hyoid, omo- hyoid, and sterno-mastoid muscle ; by its internal surface, with the trachea, inferior-thyroid veins, thyroid gland, lower part of the larynx, sheath of the common carotid artery and internal jugular vein, subclavian vein, vena innominata, and on the right side, arteria innominata. The middle thyroid vein lies along its inner border. Nerve-supply.—Descendens cervicis. The THYRO-HYOID is the continuation upwards of the sterno- thyroid muscle. It arises from the oblique line on the thyroid car- tilage, and is inserted into the lower border of the body, and great cornu of the os hyoides for one-half its length. Relations.—By its external surface with the sterno-hyoid and omo-hyoid muscle ; by its internal surface with the great ala of the thyroid cartilage, thyro-hyoid membrane, and superior laryngeal artery and nerve. Nerve-supply.—A special branch of the hypoglossal. The OMO-HYOID (&>p>y, shoulder) is a double-bellied muscle passing obliquely across the neck from the scapula to the os hyoides; it forms an obtuse angle behind the sterno-mastoid, and is retained in that position by a process of the deep cervical fascia which forms a sheath for its tendon and holds it in connection with the sternum and first rib. It arises from the upper border of the scapula and transverse ligament of the suprascapular notch, and is inserted into the hyoid bone at the junction of the body and great cornu. Relations.—By its superficial surface with the trapezius, sub- clavius, clavicle, deep cervical fascia, platsyma myoides, sterno- mastoid, and integument. By its deep surface with the brachial plexus, scaleni muscles, phrenic nerve, sheath of the common carotid artery and jugular vein, descendens cervicis nerve, sterno-thyroid and thyro-hyoid muscle, and the sterno-hyoid at its insertion. Nerve-supply. —1 lescendens cervicis. Actions.—The four muscles of this group are depressors of the hyoid bone and larynx, the three former drawing these parts downwards in the middle line, and the two omo-hyoid muscles regulating their traction to the one or other side of the neck, accord- ing to the position of the head. The omo-hyoid muscles, by means of their connection with the deep cervical fascia, are rendered tensors of that portion of the deep fascia which covers the lower part of the neck, between the two sterno-mastoid muscles. The thyro- hyoid muscles, by approximating the hyoid bone to the thyroid cartilage, relax the hyo-epiglottic ligament, and permit the epiglottis to fall down over the aperture of the larynx during deglutition (G. Buchanan). 254 ELEVATOR MUSCLES OK THE HYOID BONE. Third Group.—Elevators of the Os Hyoides. Digastricus, Stylo-hyoid, Mylo-hyoid, Genio-hyoid, Genio-hyo-glossus. Dissection.—These are best dissected by placing a high block beneath the neck, and throwing the head backwards. The integu- ment has been already dissected away, and the removal of ... me areolar tissue and fat brings them clearly into view. The DIGASTRICUS (Sty, twee ; yaaryp, belly ; biventer) is a small muscle situated immediate..j beneath the side of the body of the lower jaw ; fleshy at each extremity, and tendinous in the middle. It arises {■ om the digastric fo .J te;' >r border of the mastoid process of the temporal bone ; pierces by its posterior belly the stylo-hyoid mwcle, and is inserted into a depression on the inner side of the ’ower jaw, close to the symphysis. The middle tendon is held in connection with the body of the os hyoides by an aponeu- rotic loop, through which it plays as through a pulley ; the loop being lubricated by a synovial membrane. A thin layer of aponeu- rosis is given off from the tendon of the digastricus at each side, which is connected with the body of the os hyoides, and forms a strong plane of fascia between the anterior portions of the two muscles. This fascia, the supra-liyoidean, is continuous with the deep cervical fascia. Relations.—By its superficial surface with the platysma myoides, sterno-mastoid, traclielo-mastoid, anterior fasciculus of the stylo- hyoid muscle, parotid gland, and submaxillary gland. By its deep surface with the styloid muscles, hyo-glossus, mylo-hyoid, external carotid artery, lingual and facial arteries, internal carotid artery, jugular vein, and hypoglossal nerve. Nerve-supply.—The anterior belly of the digastric muscle is supplied by the mylo-hyoid nerve, a branch of the inferior maxil- lary ; the posterior belly by a branch of the facial. The STYLO-HYOID is a small and slender muscle situated in immediate relation with the posterior belly of the digastricus, by which it is pierced. It arises from the middle of the styloid process, its outer side, and is inserted in the body of the os hyoides near the union of the lesser cornu with the body. Relations.—By its superficial surface with the posterior belly of the digastricus, parotid gland and submaxillarv gland ; its deep rela- tions are similar to those of the posterior belly of the digastricus. Nerve-supply.—A branch of the facial. Dissection.—The digastricus and stylo-hyoid must be removed from their connection with the lower jaw and os hvoides, and turned aside, in order to see the next muscle. The MYLO-HYOID (pv\y, mola, i.e., attached to the molar ridge of the lower jaw) is a broad and triangular plane of muscular fibres, forming, with its fellow of the opposite side, the tloor of the mouth. ELEVATOR MUSCLES OF THE HYOID BONE. 255 It arises from the whole length of the molar ridge of the lower jaw, from the symphysis to the last molar tooth, and proceeds inwards and backwards to the middle line, where its fibres are continuous with those of the opposite side, the posterior fibres being inserted into the body of the os hyoides. At the middle line the union is tendinous on the upper surface in front, on the lower behind, the rest being fleshy. Relations.—By its superficial or inferior surface, with the pla- ty.'„ja myoides, digastricus, supra-hyoidean fascia, submaxillary gland, submental artery and mylo-liyoidean nerve and artery. By its deep or superior surface with the genio-hyoid, genio-hyo-glossus, hyo-glossus, stvlo-glossus, gustatory nt .•, t, -hypoglossal nerve, Whar- Fig.' 189. — Styloid muscles and muscles of the tongue. 1. Tem- poral bone of the left side. 2, 2. The right side of the lower jaw, divided at its symphysis, the left side having been removed. 3. Tongue. 4. Genio-hyoid. 5. Genio- hyo-glossus. 6. Hyo-glossus ; its basio-glossus portion. 7. Its cerato-glossusportion. 8. Anterior fibres of the inferior lingualis issu- ing from between the hyo-glossus and genio-liyo-glossus. 9. Stylo- glossus with part of the stylo- maxillary ligament. 10. Stylo- hyoid. 11. Stylo - pharyngeus. 12. Os hyoides. 13. Thyro-hyoid membrane. 14. Thyroid cartilage. 15. Thyro-hyoid muscle arising from the oblique line of the thyroid cartilage. 16. Cricoid cartilage. 17. Crico-thyroid membrane, through which the operation of laryngotomy is performed. 18. Trachea. 19. Commencement of the oesophagus. ton’s duct, sublingual gland, and mucous membrane of the floor of the mouth. Nerve-supply.—The mylo-hyoid nerve, a branch of the inferior dental, which supplies it on its lower or superficial surface. Dissection.—After the mylo-hyoid has been examined, it should be cut away from its origin and insertion, and completely removed. The view of the next muscles would also be improved by dividing the lower jaw a little to the side of the symphysis, and drawing it outwards ; or removing it altogether if the ramus have been already cut across in dissecting the internal pterygoid muscle. The tongue may then be drawn out of the mouth by means of a hook. The GENIO-HYOID (yeveiov, the chin) arises from a small tubercle on the inner side of the symphysis of the lower jaw, and is inserted into the body of the os hyoides, It is a short and slender muscle, 256 MUSCLES OF THE TONGUE. closely connected with its fellow and with the border of the following. Relations.—By its superficial or inferior surface with the mylo- hyoid ; by the deep or superior surface with the lower border of the genio-hyo-glossus. Nerve-supply.—The hypoglossal nerve. The GENIO-HYO-GLOSSUS (yXSxraa, the tongue) is a triangular muscle, narrow and pointed at its origin from the lower jaw, broad and fan-shaped at its attachment to the tongue. It arises from a tubercle above that of the genio-hyoid, and spreads out to be inserted into the whole length of the tongue, from base to apex, and into the body of the os hyoides. Relations.—By its inner surface with its fellow of the opposite side. By its outer surface with the mylo-hvoid, hyo-glossus, stylo- glossus, lingualis, sublingual gland, lingual artery, gustatory nerve, and hypoglossal nerve. By its upper border with mucous membrane of the floor of the mouth, in the situation of the framum linguae ; by its lower border with the genio-hyoid. Nerve-supply.—The hypoglossal nerve. Actions.—All the members of this group of muscles act on the os hyoides when the lower jaw is fixed, and on the lower jaw when the os hyoides is drawn downwards and fixed by its depressor muscles. They act, therefore, as depressors of the jaw or as elevators of the hyoid bone. The genio-hyo-glossus is, moreover, a muscle of the tongue; its action upon that organ will be considered with the next group. Fourth Group.—Muscles of the Tongue. Genio-hyo-glossus, Hyo-glossus, Lingualis, Stylo-glossus, Dissection.—These are already exposed by the preparation we have just made; there remains, therefore, only to dissect and examine them. The substance of the tongue is chiefly composed of muscular fibres; these are divisible into two sets, the extrinsic and in- trinsic. The extrinsic muscles are the genio-hyo-glossus, hyo- glossus, stylo-glossus and palato-glossus. The intrinsic muscles of the tongue form the great bulk of that organ, and are known collectively under the general title of lingualis. The genio-hyo-glossus, the first of these muscles, has been de- scribed with the last group. The HYO-GLOSSUS is a square-shaped plane of muscle, arising from the whole length of the great cornu, the lesser cornu, and side of the body of the os hyoides ; and inserted between the stylo-glossus and lingualis into the side of the tongue. The direction of the fibres which arise from the body is obliquely backwards ; those from the great cornu pass obliquely forwards ; hence they are described by Palato-glossus. MUSCLES OF THE TONGUE 257 Albinus as two muscles, under the names of basio-glossus and cerato-glossus, to which he added a third fasciculus, arising from the lesser cornu, and spreading along the side of the tongue, the cliondro-glossus. The basio-glossus slightly overlaps the upper part of the cerato-glossus, and is separated from it by the transverse portion of the stvlo-glossus. Relations.—By its external surface with the digastric, stylo-hyoid, stylo-glossus, mylo-hyoid, gustatory nerve, hypoglossal nerve, Whar- ton’s duct, and sublingual gland. By its internal surface with the middle constrictor of the pharynx, lingualis, genio-hyo-glossus, lingual artery, and glosso-pharyngeal nerve. Nerve-supply.—The hypoglossal nerve. THE LINGUALIS.—Muscular fibres may be seen towards the apex of the tongue, issuing from the interval be- tween the liyo-glossus and genio-hyo-glossus ; these constitute the lin- gualis longitudinalis inferior. It consists of a small fasciculus of fibres running longitudinally from the base, where it is attached to the oshyoides, to the apex of the tongue. The other muscles en- tering into the structure of the tongue, are the lingualis longitudinalis superior vel superfici- alis, the lingualis trans- versus, and the lingualis verticalis. The lingua- lis superior forms a thin plane on the upper surface of the organ, lying immediately beneath the mucous membrane, and is intermixed with fine areolar and adipose tissue. This layer is thicker in front than behind, and is covered posteriorly by a thin stratum of transverse fibres derived from the hyo-glossus. The lingualis transversus con- stitutes the chief bulk of the tongue ; it lies between the lingualis superior and inferior, its fibres being attached at the middle line to the fibrous septum of the tongue, and laterally to the mucous mem- brane ; some of its fibres are continuous with those of the stylo- glossus, hyo-glossus, and palato-glossus. The lingualis verticalis forms a series of curves in each half of the tongue, intersecting the transverse lingualis, and extending from the dorsum to the under surface, where many of the fibres become continuous with those of the genio-hyo-glossus. The fibres of the muscular struc- ture of the tongue are separated from each other by a large quantity of verv fine fat and some glandular tissue. The lateral halves of Fig. 190.—Extrinsic and intrinsic muscles of the tongue. “1. Mucous membrane. 2. Superficial longitudinal lingualis. 3. Transverse lingualis. 4, 4. Inferior longitudinal lingualis. 5, 5. Genio- hyo-glossus. 6, 6. Hyo-glossus. 7. Stylo-glossus. 8. Glands.) 258 the tongue are divided by a fibrous septum, which involves only the inner or medullary portion of the muscular mass, but is suffi- ciently complete to prevent anastomosis of the arteries of one side with those of the other. Nerve-supply.—The several layers of muscular fibre which con- stitute the lingualis muscle are chiefly supplied by the hypoglossal nerve, but some filaments of the facial also reach them. The STYLO GLOSSUS arises from the apex of the styloid process and from the stylo-maxillai’y ligament; it divides on the side of the tongue into two parts, one transverse, which passes inwards between the two portions of the hyo-glossus, and is lost among the transverse fibres of the substance of the tongue ; the other longitudinal, which spreads out upon the side of the tongue, and is prolonged forwards with the inferior lingualis as far as its tip. Relations.—By its external surface with the internal pterygoid muscle, gustatory nerve, parotid gland, sublingual gland, and mucous membrane of the floor of the mouth. By its internal surface with the tonsil, superior constrictor of the pharynx, and hyo-glossus. Nerve-supply.—The hypoglossal and facial nerves. The PALATOGLOSSUS passes between the soft palate and the side of the base of the tongue, forming a prominence of the mucous membrane, which is called the anterior pillar of the fauces. Its fibres are spread out superiorly among the muscular fibres of the palato-pharyngeus, and interiorly among the fibres of the stylo- glossus upon the side of the tongue. Nerve-supply.—This muscle is supplied by branches from Meckel’s ganglion and the pharyngeal plexus ; the motor filaments being ultimately traceable to the facial. Actions.- The genio-hyo-glossus muscle effects several move- ments of the tongue. When the tongue is steadied and pointed bv the other muscles, the posterior fibres of the genio-hyo-glossus would dart it from the mouth, while its anterior fibres would restore it to its former position. The whole length of the muscle acting on the tongue, would render it concave along the middle line, and form a channel for the current of fluid towards the pharynx, as in sucking. The apex of the tongue is directed to the roof of the mouth, and rendered convex from before back- wards by the linguales. The liyo-glossi, by drawing down the sides of the tongue, render it convex along the middle line. It is drawn upwards at its base by the palato-glossi, and backwards or to either side by the stylo-glossi. The palato-glossi muscles, assisted by the uvula, have the power of closing the fauces com- pletely, an action which takes place in deglutition. The lingualis fibres are mainly brought into play in the production of articulate speech. MUSCLES OF THE TONGUE. MUSCLES OF THE PHARYNX. 259 Fifth Group.—Muscles of the Pharynx. Inferior constrictor, Middle constrictor, Superior constrictor, Stvlo-pharyngeus, Palato-pharvngeus. fSDissection.—To dissect the pharynx, the trachea and oesophagus are to be cut through at the lower part of the neck, and drawn upwards by dividing the loose areolar tissue which connects the back of the pharynx with the vertebral column. The saw is then to be applied behind the styloid processes, and the base of the skull sawn through. The vessels and loose structures should be removed Fir:. 191.—Dissection of the constrictor mus- cles of the pharynx with the vessels and nerves in relation with them. 1. Pha- ryngeal aponeurosis. 2, 2. Glosso-pliaryn- geal nerve. 3. Poste- rior belly of digastric. 4. 4. Vagus nerve. 5. Splenius capitis. 6. Spinal - accessory nerve. 7. Superior constrictormusele. 8. Internal j ugular vein. 9. Ascending pharyn- geal artery. 10. Hypo- glossal nerve. u. Stylo - pharyngeus. 12. Superior ganglion of sympathetic. 13. Stemo-mastoid. 14. Pharyngeal branch of pneumogastric. 15. Middle constrictor. 16. Superior laryngeal nerve. 17. Common carotid artery. 18. Middle ganglion of sympathetic. 19. In- ferior constrictor. 20. Cardiac nerves. 21. (Esophagus. 22. Recurrent laryngeal from the preparation, and the pharynx stuffed with tow or wool for the purpose of distending it, and rendering the muscles more easy of dissection. Fascia.—The pharyngeal fascia or aponeurosis is a strong sheet situated between the muscles and mucous membrane ; it is especially strong at its upper part, where it fills in the interval left above the festooned upper margin of the superior constrictor, and is attached to the basilar process of the occipital bone and petrous portion of the temporal. It is strengthened in the middle line by a strong band, which is attached to the pharyngeal tubercle on the basilar process of the occipital bone ; this has been named by Cleland the cranio- 260 CONSTRICTOR MUSCLES. pharyngeal ligament. As it passes down, the fascia gradually becomes thinner, and at the lower part of the pharynx is distin- guishable only as a layer of connective tissue uniting the mucous and muscular coats. The constrictors of the pharynx are web-like sheets of muscle with fibres differently disposed, which form a muscular bag attached to the base of the skull. This bag communicates in front with the mouth. Each of the constrictors may be described as having one posterior attachment and several lateral. The INFERIOR CONSTRICTOR, the thickest of the three con- strictor muscles, arises from the cricoid cartilage, and the inferior cornu and oblique line of the thyroid. Some fibres are continuous with those of the sterno-thyroid, thyro-hyoid, and crico-tliyroid muscles : inferiorlv it is blended with the transverse fibres of the Fig. 192.—Side view of the muscles of the pharynx. 1. Trachea. 2. Cricoid car- tilage. 3. Crico-tliyroid membrane. 4. Thyroid cartilage. 5. Thyro-hyoid membrane. 6. Os liyoides. 7. Stylo- hyoid ligament. 8. (Esophagus. 9. Inferior constrictor. 10. Middle con- strictor. 11. Superior constrictor. 12. Stylo-pharyngeus, passing down be- tween the superior and middle con- strictor. 13. Upper concave border of superior constrictor; at this point the muscular fibres of the pharynx are deficient. 14. Pterygo-niaxillary liga- ment. 15. lluccinator. 16. Orbicu- laris oris. 17. Mylo-liyoid. oesophagus. Its fibres spread out, and are inserted into the middle line of the pharynx, the inferior fibres being almost horizontal, the superior oblique and overlapping the middle constrictor. Relations.—By its external surface with the vertebral column, longus colli, sheath of the common carotid artery, sterno-thyroid muscle, thyroid gland, and some lymphatic glands. By its internal surface with the middle constrictor, stylo-pharyngeus, palato-pharyn- geus, and mucous membrane of the pharynx. By its lower border, near the cricoid cartilage, it is in relation with the recurrent laryngeal nerve ; and by the upper border with the superior laryn- geal nerve. The muscle must be removed before the next can be fully seen. The MIDDLE CONSTRICTOR arises from the great cornu of the os hyoides, from the lesser cornu, and from the stvlo-hvoid liga- ment. It radiates from its origin, and spreads ont upon the side of the pharynx, the lower fibres descending and being overlapped by the inferior constrictor ; the upper fibres ascending, so as to cover in the superior constrictor. It is inserted into the raphe of the pharynx, and by a fibrous aponeurosis into the basilar process of the occipital bone. Relations.—By its external surface with the vertebral column, longus colli, rectus anticus major, carotid vessels, inferior constrictor, hyo-glossus, lingual artery, pharyngeal plexus of nerves, and some lymphatic glands. By its internal surface with the superior con- strictor, stylo-pharyngeus, palato-pharyngeus, and mucous membrane of the pharynx. The upper portion of this muscle must be turned down, to bring the whole of the superior constrictor into view ; in so doing, the stylo-pharyngeus muscle will be seen passing behind its upper border. The SUPERIOR CONSTRICTOR is a thin and quadrilateral plane of muscular fibres arising from the side of the tongue, the mucous membrane of the floor of the mouth, the extremity of the molar ridge of the lower jaw, the pterygo-maxillary ligament, and lower third of the posterior margin of the internal pterygoid plate ; and inserted into the raphe of the pharynx and basilar process of the occipital bone. Its superior fibres are arched, leaving a concave interspace between its upper border and the basilar process ; some of its lower fibres are continuous with those of the genio-hyo-glossus on the side of the tongue, and it is overlapped interiorly by the middle constrictor. Relations.—By its external surface with the vertebral column and muscles of the latter, behind ; with the vessels and nerves contained in the niaxillo-pliaryngeal space laterally, and with the middle con- strictor, stylo-]haryngeus, and tensor palati. By its internal surface with the levator palati, palato-pharyngeus, tonsil, and mucous mem- brane of the pharynx. Nerve-supply.—The constrictor muscles of the pharynx are supplied by a plexus of nerves derived from the superior laryngeal and pharyngeal branches of the pneumogastric, the glosso-pharyn- geal, and cervical plexus, mixed with some fibres from the sym- pathetic. Muscular Interspaces.—The three constrictor muscles of the pharynx, having festooned upper edges, necessarily leave between them muscular interspaces; these being occupied by important structures, require to be recognised and remembered. The first is placed between the upper edge of the superior constrictor and the base of the skull, and has received the name of Sinus of Mor- gagni ; it gives passage to the Eustachian tube, levator palati muscle, and a branch of the ascending pharyngeal artery, and is closed in by the pharyngeal aponeurosis and mucous membrane. The second space is between the superior and middle constrictors ; it contains the stylo-pharyngeus muscle and glosso-pharyngeal nerve. SUPERIOR CONSTRICTOR MUSCLE. 261 262 MUSCLES OF THE PHARYNX. The third space forms the interval between the middle and inferior- constrictors ; it corresponds to the lateral part of the thyroid-hyoid membrane, and transmits the superior laryngeal nerve and artery. Maxillo-Pharyngeal Space.—Between the side of the pharynx and ramus of the lower jaw is a triangular interval, the maxillo- pharyngeal space, which is bounded at the inner side by the supe- rior constrictor muscle; at the outer side by the internal pterygoid muscle; and behind by the rectus anticus major and vertebral column. In this space are situated the internal carotid artery, ascending pharyngeal artery, internal jugular vein, glosso-pliaryn- geal, pneumogastric, spinal accessory, sympathetic, and hypoglossal nerves. The STYLO-PHARYNGEUS is a long and slender muscle arising from the inner side of the base of the styloid process ; it descends between the superior and middle constrictor muscles, and spreads out beneath the mucous membrane of the pharynx ; it is inserted partly into the posterior border of the thyroid cartilage and partly into the internal face of the inferior constrictor. Relations.—By its external surface with the stylo-glossus muscle, external carotid artery, parotid gland, and middle constrictor. By its internal surface with the internal carotid artery, internal jugular vein, superior constrictor, palato-pliaryngeus, and mucous membrane. Along its lower border is seen the glosso-pharyngeal nerve, which crosses it opposite the root of the tongue, to pass between the superior and middle constrictor and behind the hyo-glossus. Nerve-supply.—Glosso-pharyngeal nerve. Associated in function with the preceding is a small muscle, not always present, the salpingo-pharyngeus a tube), which arises from the lower border of the Eustachian tube near its aperture, and passes down upon the inner surface of the side of the pharynx, where it becomes united with the palato-pliaryngeus. The palato-pharyngeus is described with the muscles of the soft palate. Actions.—The three constrictor muscles are important agents in deglutition ; they contract upon the morsel of food as soon as it is received by the pharynx, and convey it downwards into the oeso- phagus. Constriction of the pharynx takes place by the anterior wall of the cavity being drawn backwards, and at the same time there is a slight upward movement of the hyoid bone and larynx in con- sequence of the oblique direction of most of the fibres of the middle and inferior constrictors. The stylo-pharyngei draw the pharynx upwards, and widen it laterally. The palato-pharyngei also draw it upwards, and with the aid of the uvula close the opening of the fauces. The salpingo-pharyngei are elevators of the upper part of the pharynx. A more complete description of the mechanism of deglutition will be given after the palate muscles have been described. MUSCLES OP THE SOFT PALATE. 263 Sixth Group.—Muscles of the Soft Palate. Levator palati, Tensor palati, Azygos uvula', Palatoglossus, Palato-pharyngeus. Dissection.—To examine these muscles, the pharynx must be opened from behind by a vertical incision, and the mucous mem- brane carefully re- moved from the pos- terior surface of the soft palate. The LEVATOR PAL ATI, a moderately thick muscle, arises from the extremity of the petrous bone in front of the opening of the carotid canal, and from the posterior and inferior aspect of the cartilage of the Eustachian- tube, and passing down by the side of the posterior nares spreads out be- tween the fasciculi of origin of the palato- pharyngeus ; it is in- serted into the middle line, where it is con- tinuous with the muscle of the opposite side, and is overlaid the azygos uvulae. In order to reach the palate it passes through the opening above the superior con- strictor muscle. Relations.—Externally with the tensor palati and superior con- strictor muscle; internally and posteriorly with the mucous mem- brane of the pharynx and soft palate ; interiorly it passes between the two fasciculi of origin of the palato-pharyngeus to reach its insertion. Nerve-supply.—Branches from Meckel’s ganglion, the motor root of which is the facial nerve. Dissection.—This muscle must be turned down from its origin on Fig. 193.—Muscles of the palate. 1. Septum uarium. 2. Eustachian tube. 3. Pterygoideus exteruus. 4. Pterygoideus internus. 5. Levator palati. 6. Tensor palati. 7. Superior constrictor of pharynx. 8. Azygos uvulae. 9. Palato-pharyngeus. 10. Stylo-pharyngeus. 11. Middle constrictor of pharynx. 12. Palato-pharyn- geus (cut). 13. Inferior constrictor of pharynx. 14. (Esophagus. MUSCLES OF THE PALATE. one side, and removed, and the superior constrictor dissected away from its pterygoid origin, to bring the next muscle into view. The TENSOR PALATI (circumflexus) is a slender and battened muscle ; it arises from the scaphoid fossa at the base of the internal pterygoid plate, from the spinous process of the sphenoid bone, the edge of the tympanic plate of the temporal bone, and from the anterior aspect of the Eustachian tube. It lies between the in- ternal pterygoid muscle and internal pterygoid plate ; the tendon winds around the liamular process of the latter, and expands into an aponeurosis, which is inserted into the transverse ridge on the horizontal portion of the palate bone, by means of the palatine aponeurosis. The tendon as it passes round the liamular process is contained in a synovial sheath. Relations.—By its external surface with the internal pterygoid muscle ; by its internal surface with the levator palati, internal pterygoid plate, and superior constrictor. In the soft palate, its tendinous expansion is placed in front of the other muscles, and in contact with the mucous membrane. Nerve-supply.—From the otic ganglion, the motor root of which is the facial nerve. Palatine Aponeurosis.—A firm but not well-defined elastic mem- brane extends from the posterior border of the palate plate into the velum of the palate ; it thins as it descends, and at the sides becomes continuous with the pharyngeal aponeurosis. It gives attachment to portions of all the palatine muscles. The AZYGOS UVULAE (motor uvulce) is a pair of small muscles situated along the mid-line of the soft palate. They arise from the spine of the palate bone and aponeurosis of the soft palate, and are inserted into the uvula. By their anterior surface they are in re- lation with the levatores palati, palato-glossi, and anterior fasciculus of the palato-pharyngei; posteriorly they have the thin posterior fasciculus of the palato-pharyngei and the mucous membrane. Nerve-supply.—Probably from Meckel’s ganglion, the nerve fibres being, however, ultimately traceable to the facial nerve. Dissection.—The two next muscles are brought into view by raising the mucous membrane from the pillars of the soft palate at each side. The PALATO-GLOSSUS (constrictor isthmi faucium) is a small fasciculus of fibres, which arises in the soft palate as a radiated expansion continuous with its fellow of the opposite side ; and descends to be inserted into the side of the tongue, where its fibres mingle with those of the transverse lingualis. It is the prominence of this small muscle, covered by mucous membrane, that constitutes the anterior pillar of the soft palate. It has been named constrictor isthmi faucium, from a function it performs in common with the palato-pharyngeus—viz., constricting the opening of the fauces. The PALATO-PHARYNGEUS (constrictor isthmi faucium posterior) forms the posterior pillar of the fauces; it arises by two fasciculi from the raphe of the soft palate, where its fibres are continuous MECHANISM OF DEGLUTITION. 265 with those of the muscle of the opposite side ; and is inserted with the stylo-pharyngeus into the inner surface of the pharynx and posterior border of the thyroid cartilage. This muscle is broad above where it forms the whole thickness of the lower half of the soft palate, narrow in the posterior pillar, and again broad and thin in the pharynx where it spreads out previously to its insertion. The levator palati passes to its insertion between the two fasciculi of origin of this muscle. Relations.—In the soft palate it is in relation with the mucous membrane both by its anterior and 'posterior surface ; above, with the levator palati, and below, with the mucous glands situated along the margin of the arch.of the palate. In the posterior pillar, it is sur- rounded for two-thirds of its extent by mucous membrane. In the pharynx, it is in relation by its outer surface with the superior and middle constrictor muscle, by its inner surface with the mucous membrane. Nerve-supply.—The palato-glossus is supplied by the facial nerve, and the palato-pharyngeus from Meckel’s ganglion and the pharyngeal plexus. Actions.—The azygos uvulae shortens the uvula. In speaking and singing, the uvula is by its muscles placed in contact with the posterior wall of the pharynx, and in that position serves to steady the palate and prevent the vibration of its edge. The levator palati raises the soft palate, while the tensor spreads it out laterally so as to form a septum between the pharynx and posterior nares. The palato-glossus and palato-pharyngeus constrict the opening of the fauces, and drawing down the soft palate, serve to press the mass of food from the dorsum of the tongue into the pharynx. The action of the pharyngeal muscles on the Eustachian tube has been much debated ; the generally received view is, that while the lower opening is always in some measure patent, it is distinctly enlarged by these muscles in the act of swallowing. Mechanism of Deglutition.—Deglutition is performed by means of the tongue and the muscles of the soft palate, fauces, and pharynx. The food bolus is pushed towards the fauces by the application of the tongue to the hard palate, the base of the tongue being also carried upwards and backwards by the action of the stylo-glossus muscles ; in this way the bolus is caused to ] >ass between the anterior pillars of the fauces, the muscles of which (the palato-glossi) contract upon it. The palato-pharyngeus muscles forming the posterior pillars of the fauces also contract and narrow the faucial opening, the interval between them being tilled up by the uvula ; the tensor palati muscles make tense, and the levator palati draw upwards and backwards the soft palate till it nearly touches the posterior wall of the pharynx, thus preventing the food from passing upwards to the nasal cavity. At the same time the larynx is drawn upwards beneath the lower jaw by the elevator muscles of the os hyoides, and the thyroid cartilage is carried beneath the hyoid bone by the thvro-hyoid muscles so as to allow the epiglottis to fall over the upper opening of the larynx, this being facilitated by the tongue being carried backwards and the glosso-epiglottic folds rendered lax. The food, being thus prevented from passing into the nose or larynx, is thrown into the grasp of the constrictors of the pharynx, which successively contract upon it from above downwards, so as to pass it into the upper part of the oesophagus. PILEVERTEBRAL MUSCLES. Seventh Group.—Praevertebral Muscles Rectus anticus major, Rectus anticus minor Scalenus anticus, Scalenus medius, Scalenus posticus, Longus colli. Dissection.—These muscles have already been exposed by the removal of the pharynx from the anterior aspect of the vertebral column ; all that is further needed is the removal of the fascia by which they are invested. The RECTUS ANTICUS MAJOR, 1 troad and thick above, narrow and pointed below, arises from the an- terior tubercles of the transverse pro- cesses of the third, fourth, fifth, and sixth cervical ver- tebrae ; and is in- serted into the basi- lar process of the occipital bone. Relations. — By its anterior surface with the pharynx, internal carotid ar- tery, internal jugular vein, superior cervical ganglion and trunk of the sympathetic nerve, pneumogastric, and spinal accessory nerve. By its posterior surface with the rectus anticus minor, and superior cervical vertebra); internally with the longus colli, and externally with the scaleni. Nerve-supply.-—Anterior division of the first cervical nerve. The RECTUS ANTICUS MINOR arises from the anterior border of the lateral mass of the atlas, and is inserted into the basilar process of the occipital bone ; its fibres being directed obliquely upwards and inwards. Fig. 194.—Praever- tebral group of muscles of the neck. 1. Rectus anticus major. 2. Scalenus anti- cus. 3. Lower oblique part of the longus colli of the right side; it is concealed superiorly by the rectus anticus major. 4. Rec- tus anticus mi- nor. s- Upper oblique portion of the longus colli. 6. Its ver- tical portion ; the figure rests on the seventh cervical verte- bra. 7. Scalenus medius; behind which is seen the scalenus pos- ticus. 8. Rectus lateralis, left side. 9. One of the intertrans- versales. Relations.—By its anterior surface with the rectus anticus major, and superior cervical ganglion of the sympathetic. By its posterior surface with the articulation of the condyle of the occipital bone with the atlas, and anterior occipito-atlantal ligament. Nerve-supply.—Anterior division of the first cervical. The SCALENUS ANTICUS is a triangular muscle, as its name implies, situated at the root of the neck, and appearing like a con- tinuation of the rectus anticus major ; it arises, by a fiat and narrow tendon, from a tubercle on the upper and inner border of the first rib ; and is inserted into the anterior tubercles of the transverse pro- cesses of the third, fourth, fifth, and sixth cervical vertebra1. Relations.— By its anterior surface with the sterno-mastoid, sub- clavius, omo-liyoicl, supra-scapular, ascending and superficial cer- SCALENUS MUSCLES. 267 Fig. 195.—Lateral view of tbe muscles of the prsevertebral region and side of the neck. 1. The mastoid process of the temporal hone. 2. The zygoma. 3. The occipital bone. 4. The spine of the scapula. 5. The acromion process. 6. The clavicle. 7. The longus colli muscle. 8. Scalenus anticus. 9. Sca- lenus medius. 10. Scalenus posticus. 11. Levator an- guli scapulae. 12. Spleni- us. 13. Complexus. 14. Cut edge of the trapezius. 15. Rhomboideus minor. 16. Serratus posticus supe- rior. 17. Supra - spinatus. 18. Opening between the scalenus anticus and medius for the subclavian artery ; the number is placed on the first rib; and the fibres below it are those of the first intercostal muscle. 19. (Esophagus and trachea. 20. Inferior constrictor of pharynx. 21. Middle con- strictor. 22. Superior con- strictor. vical arteries, phrenic nerve, and subclavian vein, by which latter it is separated from the subclavius muscle and clavicle. By its posterior surface with the pleura, the nerves which form the brachial plexus, and below, the subclavian artery. By its inner side with the longus colli, being separated by the vertebral artery; by its outer side with the scalenus medius. Its relations with the sub- clavian artery and vein are important, the vein being before, the artery behind the muscle. Nerve-supply.—Branches of the lower cervical nerves. The SCALENUS MEDIUS, the largest of the three, arises from the first rib between the groove for the subclavian artery and the tubercle, and is inserted by separate tendons into the posterior 268 PILEVEhTEBRAL MUSCLES. tubercles of the transverse processes of all the cervical vertebrae excepting the first. Nerve-supply.—Branches of the lower cervical nerves. The SCALENUS POSTICUS, of small size, arises by a thin tendon from the second rib between its tubercle and angle, and divides superiorly into two or three tendons, which are inserted into the posterior tubercles of the transverse processes of the two or three lower cervical vertebrae. Nerve-supply.—Branches from the brachial and cervical plexus. The LONGUS COLLI is a long and hat muscle, consisting of three portions, two oblique and one vertical. The superior oblique por- tion arises from the anterior tubercle of the atlas, and is inserted into the anterior tubercles of the transverse processes of the third, fourth, and fifth cervical vertebrae. The inferior oblique portion arises from the transverse processes of the fifth and sixth cervical vertebrae, and passes down the neck to be inserted into the bodies of the two or three upper dorsal vertebrae. The vertical portion arises from the bodies of the second, third, and fourth cervical vertebra;, and is inserted into the bodies of the three lower cervical and three upper dorsal vertebrae. In general terms, the muscle is attached to the bodies and trans- verse processes of the six superior cervical vertebrae above, and to the bodies of the last three cervical and first three dorsal below. Relations.—By its anterior surface with the pharynx, oesophagus ; sheath of the common carotid, internal jugular vein and pneuino- gastric nerve ; sympathetic nerve, inferior laryngeal nerve, and in- ferior thyroid artery. By its posterior surface it rests on the cervical and upper dorsal vertebrae. Nerve-supply.—Brachial plexus. Actions.—The rectus anticus major and minor preserve the equi- librium of the head upon the atlas ; and acting with the longus colli, Hex and rotate the head and the cervical portion of the vertebral column. The scaleni muscles are flexors of the vertebral column ; and, acting from above, fix the first and second ribs for the inspira- tory muscles, and themselves act as muscles of forced inspiration. Eighth Group.—Muscles of the Larynx. These muscles are described with the anatomy of the larynx, in Part VII. MUSCLES AND FASCLE OF THE TRUNK The muscles of the trunk may be subdivided into four natural groups, viz. :— 1. Muscles of the hack. 2. Muscles of the thorax. 3. Muscles of the abdomen. 4. Muscles of the perinaoum. MUSCLES OF THE BACK r. Muscles of the Back.—The region of the hade, in consequence of its extent, is common to the neck, upper extremities, and abdo- men ; and its muscles, which are numerous, may be arranged into six lavers. First Layer. Trapezius, Latissimus dorsi. Dissection.—Tlie muscles of this layer are to be dissected by making an incision along the middle line of the back, from the tubercle on the occipital bone to the coccyx. From the upper end of this incision carry a second transversely outwards to the back of the ear ; interiorly an incision must be made from tlie extremity of the sacrum, along tlie crest of the ilium, to about its middle. For convenience of dissection, a fourth may be carried from tlie spine of the seventh cervical vertebra to the acromion process. The integument and superficial fascia, together, are to be dissected off the muscles in the course of their fibres, over the whole of this region. Fasciae.—The superficial fascia of this region is continuous with that of the rest of the body ; it is of considerable thickness and strength, and contains much pinkish fat. The deep fascia forms a dense fibrous layer which is attached to the superior curved line of the occipital bone, the spines of the vertebrae, spine of the scapula, crest of the ilium, and sacrum ; it is closely connected with the muscles, for which it forms sheaths, and is continuous with the deep cervical fascia and with tlie deep fascia of the abdominal and thoracic walls. The TRAPEZIUS muscle (trapezium, a quadrangle with unequal sides) arises from the inner third of the superior curved line of the occipital bone, from the ligamentum nuchae, and from the supra- spinous ligament and spinous processes of the last cervical and all the dorsal vertebrae. The fibres converge from these various points, the upper and lower being oblique, and tlie middle nearly horizontal, and are inserted into the scapular third of the clavicle, acromion process, and upper border of the spine of the scapula, as far back as its tubercle. Over the two lower cervical and two upper dorsal spines the origin is markedly aponeurotic, so as to present the appear- ance of a tendinous ellipse. The lower fibres of the muscles termi- nate in a flattened tendon which plays over the smooth triangular area at the root of the spine of the scapula. When the trapezius is dissected on both sides, the two muscles resemble .a trapezium, or diamond-shaped quadrangle, on the posterior part of the shoulders ; hence the muscle was formerly named cucullaris (cucullus, a monk’s cowl). Relations.—By its superficial surface with the integument and superficial fascia, to which it is closely adherent by its cervical portion, loosely by its dorsal portion. By its deep surface, from above downwards, with the complexus, splenius, levator anguli 270 MUSCLES OF THE BACK scapulae, supra-spinatus, rhomboideus minor, rhomboideus major and small portions of the infra-spinatus, serratus posticus superior, latissimus dorsi and vertebral aponeurosis, the latter separating Imo. 196.—First, second, and part of the third layer of muscles of the back • the first layer occupies the right, the second, the left side. 1. Trapezius. 2 Tendinous portion, forming, with a corresponding part of the opposite muscle the ten'- unions ellipse on the back ot the neck. 3. Acromion process and spine of the scapula. 4 Latissimus dorsi. s. Deltoid. 6. Muscles of the dorsum of the scapula; infra-spinatus teres minor, and teres major. 7. Obliquus externus. 8. Gluteus medius. 9. Glutei maxnni. 10. Levator anguli scapula? u Rhom- boideus minor 12. Rhomboideus major. 13. Splenius capitis; the muscle immediately above, and overlaid by the splenius, is the complex 14 Splenius colli, partially seen ; the common origin of the splenius is seen attached to the spinous processes below the origin of the rhomboideus major Lumbar aponeurosis. 16. Serratus posticus inferior. i7. Supra-spinatus 18 Infra- spinatus 19. Teres minor. 20. Teres major. 21. Long head of triceps,'passing interims ereS mmor an<* maJor the arm» 22. Serratus magnus, 23. Obliquus LATISSIMUS DORSI. 271 it from the erector spinae. The anterior border of the cervical portion forms the posterior boundary of the posterior triangle of the neck. Its clavicular insertion sometimes advances to the middle of the clavicle, or as far as the outer border of the sterno-mastoid, and occasionally it has been seen to overlap the latter. This is a point to be borne in mind in the operation for ligature of the sub- clavian artery. The spinal accessory nerve passes beneath the anterior border, near the clavicle, previously to its distribution to the under surface of the muscle. Nerve-supply.—Spinal accessory, and third and fourth cervical. The ligamentum nuchas is a band composed of white fibrous tissue extended from the tubercle and spine of the occipital bone to the spinous process of the seventh cervical vertebra, where it is continuous with the supraspinous ligament. It is connected with the spinous processes of all the cervical vertebrae, excepting the atlas, by means of a series of small fibrous slips ; and is the homologue of an important elastic ligament in animals. The LATISSIMUS DORSI muscle covers the whole of the lower part of the back and loins. It arises from the spinous processes of the six inferior dorsal, and all the lumbar vertebrae, from the supraspinous ligament, spinous tubercles of the sacrum, posterior third of the outer lip of the crest of the ilium, and four lower ribs ; the latter origin taking place by muscular slips, which in- digitate with the external oblique muscle of the abdomen. The fibres from this extensive origin converge as they ascend, and cross the inferior angle of the scapula ; they then curve around the lower border of the teres major muscle, and terminate in a short quadrilateral tendon, which gets in front of the tendon of the teres, and is inserted into the bicipital groove of the humerus. The tendinous origin of the muscle is united by its under surface with the posterior lamella of the fascia lumborum. A synovial bursa is interposed between its upper border and the lower angle of the scapula, and another between the upper half of its tendon and that of the teres major; the two tendons being united in- teriorly. The muscle frequently receives a small fasciculus from the scapula as it crosses its inferior angle; its tendon also gives off fibres to the dee]) fascia of the upper arm. In many instances, a muscular slip arises from the edge of the latissimus where it forms the posterior fold of the axilla, and cross- ing the axillary artery terminates by joining the under surface of the pectoralis major, or the coraco-brachialis. This is called the musculus axillaris (dorsi-axillaris of Macalister). At the upper border of the latissimus is a small triangular interval (triangle of Clark), bounded above by the lower border of the rhomboideus major, within by the trapezius, and below by the latissimus dorsi; in this space the ribs and intercostal muscles are seen to be uncovered by the muscles of the back. Relations.—By its superficial surface with the integument and superficial fascia, and with the trapezius. By its deep surface, from RHOMBOIDEUS MUSCLES. below upwards, with the erector spina?, serratus posticus inferior, posterior aponeurosis of the obliquus interims, obliquus externus, serratus magnus, intercostal muscles and ribs, rhomboideus major, inferior angle of the scapula, and teres major. The latissimus dorsi, with the teres major, forms the posterior border of the axilla. Nerve-supply.—By the long subscapular branch of the posterior cord of the brachial plexus, and by the posterior branches of the dorsal and lumbar nerves. Second Layer. Levator anguli scapula-, Rhomboideus minor, Rhomboideus tnajor. Dissection.—This layer is brought into view by dividing the two ](receding muscles near their origin, and turning them aside. The LEVATOR ANGULI SCAPULA arises, by tendinous slips, from the posterior tubercles of the transverse processes of the four upper cervical vertebrae; and is inserted into the upper angle and posterior border of the scapula, as far as the triangular smooth surface at the root of its spine. Being the principal elevator of the shoulder, it has been termed musculus patientioc. Relations.—By its superficial surface with the trapezius, sterno- mastoid, and integument. By its deep surface with the splenitis colli, transversalis cervicis, cervicalis ascendens, scalenus posticus and serratus posticus superior, and with the superficialis colli and posterior scapular arteries. The tendons of origin are interposed between the attachments of the scalenus medius in front and the splenius colli and transversalis cervicis behind. Nerve-supply.—By the rhomboid branch of the brachial plexus, and branches from the second, third, and fourth cervical. The RHOMBOIDEUS MINOR (rhombus, a parallelogram with four equal sides) is a narrow slip of muscle, detached from the rhom- boid eus major by a slight areolar interspace. It arises from the spinous processes of the last cervical and first dorsal vertebrae and ligamentum nuehae ; and is inserted into the edge of the triangular surface on the posterior border of the scapula. The RHOMBOIDEUS MAJOR arises from the spinous processes and supra-spinous ligaments of the four upper dorsal vertebrae, and is inserted into the posterior border of the scapula as far as its inferior angle. The insertion is effected by means of a tendinous band, which is attached above to the triangular surface at the root of the spine, below to the inferior angle, and between these points to the posterior border of the scapula by means of a thin membrane. Relations.—By their superficial surface the rhomboid muscles are in relation with the trapezius, and the rhomboideus major with the latissimus dorsi and integument; bv their deep surface with the serratus posticus superior, erector spinas, posterior scapular artery, intercostal muscles and ribs. SERRATUS POSTICUS MUSCLES. Nerve-supply.—The rhomboid muscles are supplied by a branch of the brachial plexus called rhomboid ; it is derived from the fifth cervical. 273 Third Layer. Serratus posticus superior, Serratus posticus inferior, Splenius. Dissection.—The third layer consists of muscles which arise from the spinous processes of the vertebral column, and pass outwards. It is brought into view by dividing the levator anguli scapulae near its insertion, and reflecting the two rhomboid muscles upwards from their insertion into the scapula. The latter muscles should now be removed. The SERRATUS POSTICUS SUPERIOR is situated at the upper part of the thorax ; it arises from the ligamentum nucha: and spinous processes of the last cervical and two upper dorsal vertebrae. The muscle passes obliquely downwards and outwards, and is inserted by four serrations into the upper border of the second, third, fourth, and fifth ribs, a little beyond their angle. Relations.—By its superficial surface with the trapezius, rhom- boideus major and minor, and serratus magnus. By its deep surface with the splenius, erector spinae, intercostal muscles and ribs. The SERRATUS POSTICUS INFERIOR arises from the spinous processes and interspinous ligaments of the two lower dorsal and two or three upper lumbar vertebrae, and passing obliquely up- wards, is inserted by four serrations into the lower border of the four inferior ribs. Both muscles consist of a thin aponeurosis for about half their extent. Relations.—By its superficial surface with the latissimus dorsi, its tendinous origin being inseparably connected with the aponeurosis of that muscle. By its deep surface with the erector spinae, inter- costal muscles, and lower ribs. The upper border is continuous with a thin tendinous layer, the vertebral aponeurosis. Nerve-supply.—The serrati muscles are supplied by the external branches of the posterior divisions of the dorsal nerves. The vertebral aponeurosis is a thin membranous expansion, composed of transverse and longitudinal fibres, extending from the upper border of the serratus posticus inferior upwards beneath the serratus posticus superior to the neck, where it is lost in the cervi- cal fascia. It is attached along the middle line to the spinous pro- cesses of the dorsal vertebra?, externally to the angles of the ribs, and becomes continuous below with the strong aponeurosis, called lumbar fascia, which contains the erector spinae and deep muscles of the back. Dissection.—The serratus posticus superior must be removed from its origin and turned outwards, to firing into view the whole extent of the splenius muscle. SPLENIUS. The SPLENIUS muscle is single at its origin, but divides soon after into two portions, which are destined to distinct insertions. It arises from the lower half of the ligamentum nucha?, the spinous process of the last cervical, and spinous processes and interspinous ligaments of the six upper dorsal vertebrae ; it divides as it ascends the neck into the splenius capitis and splenius colli. The splenius capitis is inserted into the rough surface of the occipital bone beneath the superior curved line, and posterior border of the mastoid process of the temporal bone. The splenius colli is inserted into the posterior tubercles of the transverse processes of the three upper cervical vertebra?. The splenius is separated from its fellow of the opposite side by a triangular interval in which is seen the complexus. Relations.—By its superficial surface with the trapezius, sterno- mastoid, levator anguli scapula?, rliomboideus minor and major, and serratus posticus superior. By its deep surface with the spinalis dorsi, longissimus dorsi, semi-spinalis colli, complexus, trachelo- mastoid, and transversalis cervicis. Nerve-supply.—The great occipital, and the external branches of the posterior divisions of the cervical and live upper dorsal nerves. Fourth Layer. Erector spina?. Cervicalis ascendens. Transversalis cervicis. Trachelo-mastoid. Complexus. Dissection.—The two serrati and two splenii muscles must he removed by cutting them away from their origin and insertion, and the vertebral aponeurosis laid open, to bring the fourth layer into view. The muscles of the fourth layer form the greater part of the muscular mass which fills up the great vertebral groove on each side of the spine ; they are often described collectively under the name of erector spinae ; but this title should correctly be limited to the fleshy and tendinous mass which springs from the back of the pelvis and the lumbar vertebrae. When the erector spina? reaches the level of the last rib, the greater part of it divides to form two muscular columns, the oiiter receiving the name of sacro-lumbalis, the inner of longissimus dorsi; these are continued as they ascend into the muscles of the upper part of the back and neck, their relation to each other being indicated in the subjoined statement. To these two columns a third is added, forming the spinalis dorsi; it is placed the most internally of the three, and is limited to the dorsal and upper lumbar region. ERECTOR SPINAL 275 Erector Spinae. Sacro-lumbalis, Longissimus dorsi, Spinalis dorsi. Musculus accessorius, Transversalis cervicis, Cervicalis ascendens. Tlie ERECTOR SPINAS arises from tlie posterior third of the crest of the ilium, the oblicpie sacro-iliac ligament, articular and spinous tubercles of the sacrum, spinous processes and transverse processes of the lumbar vertebrae ; the external portion being Meshy, the internal tendinous. The tendinous portion is broad and Mat, and gives origin by its deep surface to a considerable part of the muscular fibres. In the lumbar region, the muscle proceeding from this extensive origin is a broad and thick musculo-tendinous mass, on the surface of which, opposite the last rib, a line of separation is apparent, the outer portion, about one-third, being the sacro-lumbalis, the inner two-thirds the longissimus dorsi. The sacro-lumbalis (ilio-costalis) ascends upon the chest inter- nally to the angles of the ribs, and is inserted by separate slips, the four upper tendinous, the two lower Meshy, into the angles of the six lower ribs. If this muscle be turned a little outwards, a number of tendinous slips will be seen which take their origin from the upper border of the ribs near their angles, and terminate in muscular fasciculi, which prolong the sacro-lumbalis to the upper part of the chest. This is the musculus accessorius ad sacro-lumbalem ; it arises from the six lower ribs, and is inserted by separate tendons into the angles of the six upper ribs and transverse process of the seventh cervical vertebra. The longissimus dorsi is inserted by two series of tendons, in- ternal and external; the internal being implanted into the accessory and transverse processes of all the lumbar, and transverse processes of all the dorsal vertebrae ; the external into the transverse processes of the lumbar vertebrae, and all the ribs, excepting the first, be- tween their tubercles and angles. The spinalis dorsi is situated at the inner side of the longis- simus dorsi, and arises from the spinous processes of the two upper lumbar and two lower dorsal vertebrae ; it is inserted into the spinous processes of. the upper dorsal vertebrae from the second to the sixth or eighth. It also receives several fascicidi from the longissimus dorsi and semi-spinalis dorsi. The two muscles form an ellipse, which embraces the spinous processes of the dorsal vertebrae. The lumbar fascia, with the spinal column, aponeurosis of the latissimus dorsi, and ribs, forms a complete osseo-aponeurotic sheath for the erector spinae. The CERVICALIS ASCENDENS vel descendens is the continua- Trachelo-mastoid. MUSCLES OF THE BACK. lion of the sacro-lumbalis ii]ovards into the neck. It arises from the angle of the third, fourth, fifth, and sixth ribs, and is inserted by slender tendons into the posterior tul mercies of the transverse processes of the third, fourth, fifth, and sixth cervical vertebrae. The term de- scended, applied to this muscle, can only be correct when it is de- scribed as arising in the neck and passing downwards to the ribs. The TRANSVERSALIS CERVICIS appears to be the continuation up- wards intotheneck of thelongissimus dorsi; it arises from the transverse processes of the five or six upper dorsal vertebrae, and is inserted, into the posterior tubercles of the trans- verse processes of the cervical verte- brae, from the second to the sixth. It receives a fasciculus from the longissimus dorsi and several small slips from the trachelo-mastoid. The TRACHELO-MASTOID is like- wise a continuation upwards from the longissimus dorsi. It is a slen- der and delicate muscle, arising from the transverse processes of the three upper dorsal and last cervical, and from the articular processes of the three next cervical vertebrae, its origin being similar to that of the eomplexus, with which and the ori- gin of the transversalis cervieis it is closely connected. It receives a fasciculus from the longissimus dorsi, and is inserted into the posterior border and summit of the mastoid process. Nerve-supply.—Tliisand the] ire- ceding muscles are supplied by the external branches of the posterior divisions of the dorsal and cervical nerves. TheCOMPLEXUS is a large muscle, forming with the splenius the great bulk of the back of the neck. It crosses the direction of the splenius, arising from the transverse processes of the three upper dorsal and last cervical, and from the articular processes of the fourth, fifth, Fid. 107.—Fourth, fifth, and part of tlic sixth layer of the muscles of the back. 1. Origin of the erector spinas. 2. Sacro-lumbalis. 3. Lon- gissimus dorsi. 4. Spinalis dorsi. 5. Cervicalisascendens. 6. Trans ver- salis cervicis. 7. Traclielo-mastoid. 8. Complexus. 9. Transversalis cer- vicis, showing its origin. 10. Semi- spinalis dorsi. n. Semi-spinalis colli. 12. Rectus posticus minor. 13. Rectus posticus major. 14. Obli- quus superior. 15. Obliquus inferior. 16. Multifidus spiuse. 17, 17. Leva- tores costarum. 18. Inter-transver- sales. 19. Quadratus lumborum. MUSCLES OF THE FIFTH LAYER. and sixth cervical vertebrae ; and is inserted into the rough surface of the occipital bone between the two curved lines, as far as the occipital spine. The complexus is marked in the upper part of the neck by a transverse tendinous intersection. A large fasciculus of the complexus lying superficially to the rest of the muscle, and remarkable for consisting of two fleshy bellies with an intermediate tendon, is usually described under the name of biventer cervicis. Considered as a separate muscle, it arises by three or four slips from the transverse processes of the dorsal vertebrae, from the fourth to the seventh ; and is inserted into the inner portion of the superior curved line of the occipital bone. Nerve-supply.—The great occipital, and internal branches of posterior divisions of the six lower cervical and five upper dorsal nerves. Fifth Layer. Semi-spinales, Rectus posticus major, Rectus posticus minor, Rectus lateralis, Obliquus inferior, Obliquus superior. Dissection.—The muscles of the preceding layer are to be re- moved, by dividing them transversely through the middle, and turning one extremity upwards, the other downwards. In this way the whole of the muscles of the fourth layer may be dissected off, and the remaining muscles of the spine brought into a state to be examined. The SEMI-SPINALES muscles are connected with the transverse and spinous processes of the vertebrae, spanning one-half the verte- bral column ; hence their name, semi-spinales. The semi-spinalis dorsi arises from the transverse processes of the dorsal vertebrae from the sixtli to the tenth ; and is inserted into the spinous processes of the four upper dorsal and two lower cervi- cal vertebra). It is united below with the spinalis dorsi, and above with the semi-spinalis colli; it also sends several small slips to the longissimus dorsi. The semi-spinalis colli, larger than the preceding, arises from the transverse processes of the five or six upper dorsal vertebrae ; and is inserted into the spinous processes of the cervical vertebrae from the second to the fifth. Nerve-supply.—The semi-spinales are supplied by the internal branches of the posterior divisions of the dorsal and cervical nerves. Occipital Group.—This group of small muscles is intended for the movements of the cranium on the atlas, and atlas on the axis. The RECTUS CAPITIS POSTICUS MAJOR arises from the spinous process of the axis, and is inserted into the inferior curved line of the occipital bone. 278 The RECTUS CAPITIS POSTICUS MINOR arises from the spinous tubercle of the atlas, and is inserted into the rough surface of the occipital bone, beneath the inferior curved line. The RECTUS CAPITIS LATERALIS arises from the transverse process of the atlas, and is inserted into the rough surface of the occipital bone, externally to the condyle. The OBLIQUUS INFERIOR CAPITIS (major) arises from the spinous process of the axis, and passes obliquely outwards to be inserted into the extremity of the transverse process of the atlas. The OBLIQUUS SUPERIOR CAPITIS (minor) arises from the extremity of the transverse process of the atlas, and passes obliquely inwards to be inserted into the rough surface of the occipital bone, be- tween the curved lines, and directly behind the mastoid process. Relations.—By their superficial surface the recti and obliqui are in relation with a strong aponeurosis which sepa- rates them from the complexus. By then- deep surface with the atlas and axis. The rectus posticus major partly covers in the rectus minor. The rectus lateralis is in relation by its anterior surface with the internal jugular vein, and by its posterior surface with the vertebral artery. Nerve-supply.—The recti and obliqui are supplied by the pos- terior divisions of the first and second cervical nerves. MUSCLES OF THE BACK. Fig. 198.—Suboccipital region. 1. Occipital artery and nerve piercing the trapezius. 2. Trapezius. 3. Occipital artery. 4. Complexus. 5. Vertebral artery. 6. Rectus capitis posticus minor. 7. Sub- occipital nerve. 8. Rectus capitis posticus major. 9. Great occipital nerve. 10. Obliquus superior. 11. Semi-spinalis colli. 12. Sterno-mastoid. 14. Splenitis capitis. 16. Traehelo-mastoid. 18. Ob- liquus inferior. Sixth Layer. Multifidus spirnc, Rotatores spina;, Interspinales, lnter-transversales. Dissection.—The semi-spinales muscles must he removed to obtain a good view of the multifidus spin®, which lies beneath them, and tills up the concavity between the spinous and transverse processes, the whole length of the vertebral column. The MULTIFIDUS SPINiE, consisting of about twenty-two small muscular fasciculi, extends along the vertebral groove from the sacrum to the axis. The muscle commences by tendinous fibres on the dorsum of the sacrum, proceeding from the lateral tubercles of the sacrum and even from the lateral cornu of the coccyx, and passing obliquely upwards and inwards to the spinous tubercles. The fasciculi arise inferiorly from the sacrum, ilium, and tendon of the erector spinse; in the lumbar region from the articular and mammillary processes of the vertebrae ; in the dorsal region from the transverse processes ; and in the cervical region from the arti- cular processes of the four inferior vertebrae. They are inserted into the spinous processes and laminae of all the vertebrae from the sacrum to the axis. Of the twenty-two fasciculi, six are lumbar, twelve dorsal, and four cervical. Each fasciculus, separate below, spreads out as it ascends, and passing over the next vertebra, is inserted into the four or five immediately above it. The muscle is thick inferiorly ; and the uppermost fasciculus larger than those im- mediately below it. T1 le ROTATORES SPINiE are situated in the dorsal region beneath the multifidus spinse ; they are eleven in number, and arise from the upper and back part of the transverse processes, and are inserted into the lamina.1 and roots of the spinous processes. The INTERSPINALES are small muscular slips arranged in pairs and situated between the spinous processes of the vertebra). In the cervical region there are six pairs of these muscles, the first being placed between the axis and third vertebra, the sixth between the last cervical and first dorsal; they are attached to the apices of the spinous processes, and are separated by the interspinous liga- ments. In the dorsal region, rudiments of these muscles are occasion- ally met with between the upper and lower vertebrae, but are absent in the rest. In the lumbar region there are six pairs of interspinales, the first pair occupying the interspinous space between the last dorsal and first lumbar vertebrae, the last, the space between the fifth lumbar and sacrum. They are thin, broad, and imperfectly developed. Rudimentary interspinales are occasionally met with between the sacrum and coccyx; these are the analogues of the caudal muscles of brutes ; in man they are named collectively the extensor coccygis (sacro-coccygeus posticus). The INTER-TRANSVERSALES are small quadrilateral muscles situated between the transverse processes of the vertebra?. In the cervical region they are arranged in pairs corresponding with the double conformation of the transverse processes, the vertebral ar- tery and anterior division of a cervical nerve lying between them. The rectus antieus minor and rectus lateralis represent the inter- transversales between the atlas and cranium. In the dorsal region the anterior inter-transversales are represented by the intercostal muscles, while the posterior are mere tendinous bands, muscular only between the first and last vertebra?. In the lumbar region, the anterior inter-transversales are thin, and occupy only part of the DEEP LAYER OF MUSCLES, 279 ACTIONS OF THE MUSCLES OF THE BACK. space between the transverse processes. Homologues of posterior inter-transversales exist in the form of small muscular fasciculi extended between the mammillary process of the lumbar vertebrae. Nerve-supply.—The multifidus spinae, interspinales, and inter- transversales, are supplied by branches from the posterior divisions of the spinal nerves, from the atlas to the sacrum. With regard to the origin and insertion of the muscles of the back, the student should be informed that no exact regularity attends their attachments. At the best, a knowledge of their precise connections, even were it possible to retain it, would be but a barren information, if not absolutely injurious, as tending to exclude more valuable learning. Actions.—The upper fibres of the trapezius draw the shoulder upwards and backwards; the middle fibres, directly backwards; the lower, downwards and backwards. The lower fibres also pro- duce rotation of the scapula on the chest, tilting the lower angle of that bone forwards and upwards, and carrying the upper angle slightly downwards and inwards ; in this way the glenoid cavity is directed obliquely upwards and outwards, and the trapezius thus performs an important part in the elevation of the arm above the shoulder. If the shoulder be fixed, the upper fibres will flex the spine towards the corresponding side. The latis- simus dorsi is a muscle of the arm, drawing it backwards and downwards, and at the same time rotating it inwards ; if the arm be fixed, the latissimus dor-si will draw the spine to that side, and, raising the lower ribs, be an inspiratory muscle; and if both arms be fixed, the two muscles will draw the whole trunk forwards, as in climbing or walking on crutches. By passing over the inferior angle of the scapula it binds that bone to the thoracic wall, and by being folded round the. axillary border it limits the outward projection of the same angle when the arm is raised. The levator anguli scapula; lifts the upper angle of the scapula, and with it, the entire shoulder ; the rliomboidei carry the scapula and shoulder upwards and backwards, and approximate the inferior angle of the scapula to the spine. The serrati are respiratory muscles acting in opposition to each other, the serratus posticus superior drawing the ribs upwards, and thereby expanding the chest ; the inferior drawing the lower ribs downwards, and diminishing the cavity of the chest. The former is an inspiratory, the latter an expiratory muscle. The splenii muscles of one side draw the vertebral column backwards and to one side, and rotate the head towards the corresponding shoulder. The muscles of opposite sides acting together, draw the head directly backwards. They are direct antagonists of the sterno- mastoid muscles. The sacro-lumbalis with its accessory muscle, the longissimus dorsi and spinalis dorsi, are known by the general term of erector spina, which sufficiently expresses their action. They keep the spine sup- ported in the vertical position by their broad origin from below, and by their insertion, by distinct tendons, into the ribs and spinous processes. Being made up of a number of distinct fasciculi, which act alternately, the spine is kept erect without fatigue, even when the muscles have to counterbalance a corpulent abdomen. The continuations upwards of these muscles into the neck preserve the steadiness and uprightness of that region. When the muscles of one side act alone, the neck is rotated on its axis. The complexus, being attached to the occipital bone, draws the head backwards, and counteracts the muscles of the anterior part of the neck. It assists also in the rotation of the head. The semi-spinalis and multifidus spince muscles act directly on the vertebrae, and contribute to the general action of supporting the vertebral column erect. The four little muscles situated between the occiput and the first two vertebrae, effect the various movements between these bones; the recti producing the antero-posterior actions, the obliqui the rota- tory motions of the atlas on the axis. The actions of the remaining muscles of the spine, the rotatores spince, interspinales and inter-transversales, are expressed in their names. They approximate their attachments, and assist the more powerful muscles in preserving the erect position of the body. MUSCLES OF THE THORAX. 281 The principal muscles situated on the front and sides of the thorax belong in their actions to the upper extremity, with which they will be described. They are t he pectoral is major .and minor, subclavius and serratus magnus. The true thoracic muscles, which appertain exclusively to the actions of the ribs, are the— MUSCLES AND FASCUE OF THE THORAX. External intercostal?, Internal intercostals, Subcostals, Triangularis stern! Levatores costarum. The intercostal muscles are two planes of muscular and tendinous fibi •es directed obliquely between adjacent ribs and closing the inter- costal spaces. They are seen partially on the reflection of the pec- toral muscles, or on the inner surface of the chest. The triangularis sterni is within the chest, and requires the removal of the anterior part of the thorax to bring it into view. Fasciae.—A thin layer of fascia covers the external surface of the external intercostal, and the inner surface of the internal muscle and a still finer layer is interposed between them. The surface layers become thicker in front, where the external intercostal is deficient, and behind, where the internal intercostal is wanting. The EXTERNAL INTERCOSTALS, eleven on each side, commence posteriorly at the tubercles of the ribs, and advance forwards to the costal cartilages, where they terminate in a thin aponeurosis (anterior INTERCOSTAL MUSCLES. intercostal membrane) which is continued onwards to the sternum. Their fibres are directed obliquely downwards and forwards, pur- suing the same line with those of the external oblique muscle of the abdomen. They are thicker than the internal intercostals, and more tendinous in structure. The INTERNAL INTERCOSTALS, also eleven on each side, com- mence anteriorly at the sternum, and extend backwards as far as the angle of the ribs, whence they are prolonged to the vertebral column by a thin aponeurosis (_'posterior intercostal membrane). Their fibres are directed obliquely downwards and backwards, correspond- ing with those of the internal oblique muscle of the abdomen, and crossing those of the external intercostals. In structure the intercostal muscles consist of an admixture of muscular and tendinous fibres. They arise from the two lips of the lower border of the rib, the external from the outer lip, the internal from the inner ; and are inserted into the upper border of the rib below, encroaching somewhat on its surfaces. Nerve-supply.—The intercostal nerves. The SUBCOSTALS are nine or ten small muscles situated within the thorax at its posterior part, and lying upon the ribs. They increase in size from above downwards, and the direction of their fibres corresponds with that of the internal intercostals. Each muscle arises from the front of a rib, and is inserted into the front of the rib but one below. They are most constant on the lower ribs. Relations.—The external intercostals, by their external surface with the muscles which immediately invest the chest, viz., pectoralis major and minor, serratus magnus, serial us posticus superior and inferior, scalenus posticus, sacro-lumbalis and longissimus dorsi with their continuations, cervicalis ascendens and transversalis cervicis, levatores costariun, and obliquus externus abdominis. By their in- ternal surface with the internal intercostals, intercostal vessels and nerves, and posteriorly with the pleura, a thin layer of fascia being interposed. The internal intercostals, by their external surface with the external intercostals, and intercostal vessels and nerves ; by their internal surface with the costal pleura, triangularis sterni, subcostals, and diaphragm. The TRIANGULARIS STERNI, situated upon the inner wall of the front of the chest, arises by a thin aponeurosis from the side of the sternum, ensiform cartilage, and sternal extremities of the costal cartilages from the third to the sixth or seventh ; it is inserted by fleshy digitations into the second, third, fourth, and fifth costal cartilages and corresponding ribs. Relations.—By its external surface with the sternum, ensiform cartilage, costal cartilages, internal intercostal muscles, and internal mammary vessels. By its internal surface with the costal pleura, areolar tissue of the anterior mediastinum, and diaphragm. The lower fibres of the triangularis sterni are continuous with those of the transversalis abdominis. Nerve-supply.—The intercostal nerves. The LEVATORES COSTARUM are divided into long and short. The short, twelve in number at each side, arise from the apex and lower border of the transverse process of the last cervical and eleven upper dorsal vertebra}; and pass downwards and outwards, radiating in their descent, to be inserted into the upper border of all the ribs, between the tubercle and angle. The uppermost muscle is the smallest, and their breadth increases from above downwards. The long muscles, four in number at each side, arise from the transverse processes of the dorsal vertebrae, the seventh to the tenth, and are inserted into the four lower ribs ; each muscle passing over a rib in its descent, and being attached to the rib below as far as its angle. The long muscles lie superficially to the short ones and increase in size from above downwards. Relations. — By their superficial surface with the sacro-lumbalis, longissimus dorsi, and transversalis cer- vicis. By their deep surface with the ribs and intercostal spaces; the short muscles close the intercostal spaces, and are united by their ex- ternal border with the ex- ternal intercostals. Nerve - supply.—The posterior divisions of the dorsal nerves. Actions of the Respira- tory Muscles.—Respiration is,produced by the alternate enlargement and diminu- tion of the capacity of the thorax ; the former result- ing in the influx of air, or inspiration, and the latter in an expulsion of air, or expiration. The enlargement of the thoracic cavity takes in its three diameters, the vertical, trans- verse, and antero-posterior ; the vertical measurement being in- creased by the descent of the diaphragm which forms the floor of the cavity, and by the elevation of the first rib; the transverse diameter by the elevation and rotation of the ribs ; and the antero- posterior by the raising of the ribs and forward projection of the sternum. Ordinary tranquil inspiration is performed by the descent of the diaphragm and the elevation of the ribs and sternum by means of the intercostal muscles ; when the act is more forcibly performed these are aided by the levatores costarum, scalene muscles, and serratus posticus superior. In full inspiration the scapula is fixed by means of the muscles which connect it with the vertebral column ; the powerful muscles which pass from the shoulder to the ACTION OF THE MUSCLES OF RESPIRATION. 283 Fio. 199.—Intercostal muscles and levatores cos- tarum. IV. Fourth dorsal vertebra. V. Fifth rib. 1, 1. Levatores costarum muscles, long and short. 2. External intercostal. 3. In- ternal intercostal. ribs are then brought into play, and by their action elevate the ribs ; these are the pectoralis major and minor, serratus magnus, and latis- simus dorsi. Much difference of opinion prevails as to the action of the external and internal intercostals, many anatomists adhering to the theory taught by Hamberger that the external are inspiratory, and the internal expiratory muscles ; while others accept the view so forcibly expounded by Hutchinson that the whole of the external and the part of the internal lying between the costal cartilages act in inspiration, and the rest of the internal intercostals in expiration. Duclienne, as the result of direct experiment on the muscles, sup- ported the theory that both muscles act in common as muscles of inspiration, by raising the ribs, and so increasing the capacity of the t horax ; and the same view has been adopted by Henle and Lusclika. Ordinary tranquil expiration is not a muscular act, but an elastic and mechanical recoil, due to the elasticity of the lung-substance and the recoil of the chest wall after the muscles of inspiration have ceased to act. In forced expiration all the muscles which depress the ribs are brought into action, more especially those forming the abdominal wall (obliqui, transversales, and recti), and the triangularis sterni and sacro-lumbalis. Lastly, it should be noted that certain muscles usually classed with those of expiration, from their being attached to the lower ribs, may in consequence of that attachment assist in inspiration, by giving a point of fixation and support for the action of the diaphragm ; such are the serratus posticus inferior and quad- ratus lumborum. The levatores costarum are generally regarded as muscles of inspiration, but Von Ebner considers them to be chiefly brought into play in lateral flexion of the dorsal spine. MUSCLES OF THE,'ABDOMEN. MUSCLES AND FASCLE OF THE ABDOMEN The muscles of the abdominal region are the—- Obliquus extern us (descendens), Obliquus interims (ascendens), Cremaster, Transversal is, Rectus, Pyramidalis, Quadratus lumborum, Psoas parvus. Diaj ihragm Dissection. The dissection of the abdominal muscles is to he commenced by making three incisions:—The first, vertical, in the middle line, from over the lower part of the sternum to the pubes ; the second, transverse, from the top of the first incision across the chest, as far back as the knife can be carried ; the third, oblique, from the umbilicus, downwards and outwards, to the anterior supe- rior spine of the ilium. The three Haps included by these incisions should then be dissected back in the direction of the fibres of the external oblique muscle, beginning at the angle of each. The in- tegument and superficial fascia should be dissected off separately, so as to enable the student to examine the relation of the vessels to the parts connected with hernia. MUSCLES OF THE TRUNK, Fm. 200.—Muscles of the anterior aspect of the trunk ; on the left side tho’supcrficial layer is seen, on the right the deeper layer, i. Pectoralis major. 2. Deltoid ; the interval between these muscles lodges the cephalic vein. 3. Anterior border of the latissimus dorsi. 4. Serratus magnus. 5. Subclavius, right side. 6. Pectoralis minor. 7. Coraco-brachialis. 8. Upper part of the biceps, showing its two heads. 9. Coracoid process of the scapula. 10. Serratus magnus, right side. 11 External intercostal muscle of the fifth intercostal space. 12. External oblique. 13. Its aponeurosis ; the median line to the right of this number is the linea alba; the curved line to its left, the linea semilunaris; the transverse lines above and below the figure, the line* transversse. 14. Poupart's ligament. 15. External abdominal ring ; the margin above the ring is the superior or internal pillar; the margin below the ring, the inferior or external pillar ; the curved intercolumnar fibres are seen proceeding upwards from Poupart's ligament to strengthen the ring. The numbers 14 and 15 are placed on the fascia lata of the thigh ; the opening to the inner side of 15 is the saphenous opening. 16. Rectus muscle of the right side brought into view by the removal of the anterior segment of its sheath ; * posterior segment of its sheath with the divided edge of the anterior segment. 17. Pyramidalis muscle. 18. Internal oblique. 19. Conjoined tendon of the internal oblique and transver- salis descending behind Poupart’s ligament to the pectineal line. 20. The arch formed between the lower curved border of the internal oblique muscle and Pon- part’s ligament; it is beneath this arch that the spermatic} cord and ‘oblique inguinal hernia pass. 286 fascia: of the abdomen. The superficial fascia at the upper part of the abdomen is con- tinuous with the superficial fascia of the thorax ; it is loose, areolar, and contains but little fat. As it descends it becomes thicker, more elastic, and very fatty, and is continued into the superficial fascia of the thigh. Over the pubes the fascia contains much coarse-grained fat, but as it passes on to the penis this ceases, and is replaced bv elastic tissue ; and on its continuation into the scrotum, a layer of unstriped muscular tissue takes the place of the fat, forming the tunica dartos. Along the linea alba and in the groin, fine fibrous bands connect the superficial fascia with the dee]) layer and with the aponeurosis of the external oblique. Branches of the superficial epigastric, superficial external pudic, and superficial circumflex iliac arteries and their companion veins ramify in the substance of the fascia, and the superficial lymphatic vessels are distributed throughout it; in the groin it lodges the inguinal lymphatic glands. The deep fascia (Scarjm,s fascia) lies on the abdominal aponeurosis, a thin layer of connective tissue being interposed. It is continued upwards over the abdomen, being closely adherent to the linea alba. From the lower part of this at- tachment a triangular piece is pro- longed to the dorsum of the penis, and is called the suspensory liga- ment of the penis, the superficial part of which is formed of elastic tissue and the deep part of white fibrous tissue. At the groin the deep fascia is attached to the fascia lata of the thigh by a piece which passes down from its under surface along the line of Poupart’s ligament, but about half an inch farther down the thigh. The deep fascia is continued down into the scrotum, where it forms a sheath for the testicle, the processes from the two sides combining in the middle line to form the septum scroti. In the perineum it becomes inseparable from the dee}) layer of the superficial fascia of that region (fascia of Colles), and is attached to the ramus of the pubes on each side. From this description it follows that if air or tluid be forced under the deep fascia, it will travel through the connective tissue all over the abdomen, and could reach the scrotum and peri- neum, but could not pass down the thigh, being prevented by the connection of the fascia with the rami of the pubes, and the attach- ment of the fascia lata in the groin ; it would, moreover, be pre- vented from infiltrating the back part of the perineum by the dee]) layer of the superficial fascia being united to the deep perineal fascia along the posterior edge of the transverse perineal muscle. Linea Alba, &c.—When the external oblique muscle is dissected on both sides, a white tendinous line will be seen along the middle of the abdomen, extending from the ensiform cartilage to the pubes ; Flo. 201.—Sec- tion showing the fasciae at the groin, i. Section of Pou- part’s liga- ment. 2. Apo- neurosis of ex- ternal oblique. 3. Fascia lata. 4. Membranous layer of the superficial fascia of the thigli. 5. Super- ficial layer. 6. Skin. 7. Scar- pa’s fascia. EXTERNAL OBLIQUE MUSCLE. 287 this is the linea alba. A little external to it, on each side, two curved lines will be observed extending from the eighth rib to the spine of the pubes, and bounding the recti muscles ; these are the linece semilunares. Some transverse lines, linea; transversathree in number, connect the line* semilunares with the linea alba ; the lowest is situated opposite the umbilicus, the middle one on a level Fi(j. 202.—Lower part of aponeurosis of external oblique muscle, and external ab- dominal ring. i. Horizontal ramus of pubes. 2. Spine of pubes. 3. Aponeurosis of external oblique. 4. External pillar of abdominal ring. 5. Internal pillar. 6. Gimbernat’s ligament. 7. Triangular fascia. 8. The cut end of the same fascia. 9. The conjoined tendon. 10. Transversalis fascia. * External abdominal ring. with the cartilage of the tenth rib, and the highest opposite the cartilage of the seventh rib. The EXTERNAL OBLIQUE MUSCLE (obliquus ext emus abdominis, descendens) is the external flat muscle of the abdomen. Its name is derived from the obliquity of its direction, and the descending course of its fibres. It arises by fleshy digitations from the external surface of the eight inferior ribs ; the five upper digitations being 288 EXTERNAL ABDOMINAL RING received between corresponding processes of the serratus niagnus, the three lower, of the latissimus doi-si. The fleshy fasciculi pro- ceeding from this extensive origin terminate on the front of the abdomen in a broad aponeurosis, and posteriorly are inserted into the outer lip of the crest of the ilium for the anterior two-thirds its length, and into the anterior superior spinous process. The apo- neurosis is united, in front, bv its under surface, with that of the obliquus interims, forming the anterior wall of the sheath of the rectus, and is inserted into the linen, alba, front of the pubes, spine of the pubes, and pectineal line. The lower border of the aponeurosis, which is stretched between the anterior superior spinous process of the ilium and the spine of the pubes, is round from being folded inwards, and forms Poupart’s ligament; the insertion into the pectineal line is Gimbernat’s ligament. Just above the crest of the pubes is the external abdominal ring, a triangular opening formed by the separation of the fibres of the aponeurosis of the external oblique. It is oblique in direction, and corresponds with the course of the fibres of the aponeurosis. It is bounded below by the crest of the pubes ; on either side by the borders of the aponeurosis, which are termed 'pillars; and above by some curved fibres (intercolumnar) which originate from Poupart/s ligament, and cross the upper angle of the ring, to give it strength. The external pillar, which is at the same time inferior from the obliquity of the opening, is inserted into the spine of the pubes ; the internal or superior pillar forms an interlacement with its fellow of the opposite side over the front of the symphysis pubis. The inner fibres of the outer pillar pass behind the spermatic cord and internal pillar of the ring, and expanding into a thin triangular sheet interlace with the corresponding fibres of the opposite side on the back part of the crest and symphysis pubis ; they receive the name of triangular fascia. The external abdominal ring gives passage to the spermatic cord in the male, and the round ligament in the female : they are both invested in their passage through it by a prolongation of the intercolumnar fibres of the external oblique muscle, the intercolumnar fascia, or spermatic fascia. Relations.—By its external surface with the superficial fascia, integument, cutaneous vessels and nerves, particularly the super- ficial epigastric and superficial circumflex iliac vessels, and latissimus dorsi, by which it is overlapped posteriorly. By its internal surface with the internal oblique, lower part of the eight inferior ribs and intercostal muscles, cremaster, spermatic cord in the male, and round ligament in the female. The upper border of the external oblique is continuous with the pectoi’alis major. Nerve-supply.—Anterior branches of the lower intercostals. Dissection.—The external oblique is now to be removed by making an incision from the anterior superior spine of the ilium towards the umbilicus as far as the aponeurosis can be separhted from the subjacent muscle. From this latter point an incision is to INTERNAL OBLIQUE MUSCLE. 289 be made to the crest of the pubis, and the aponeurosis included in these incisions to be turned down to Poupart’s ligament. The remainder of the muscle may be removed by carrying a perpen- dicular incision from the end of the first up to the chest, and dis- secting off the aponeurosis and muscle. The INTERNAL OBLIQUE MUSCLE (obliquus 'internus abdominis, ascendens) is the middle flat muscle of the abdomen. It arises from the outer half of Poupart’s ligament, from the middle of the crest of the ilium for the anterior two-thirds its length, and from the fascia lumborum. Its fibres diverge from their origin, those from Pou- part’s ligament curving downwards, those from the anterior part of the crest of the ilium passing transversely, and the rest ascending obliquely. The muscle is inserted into the pectineal line and crest of the pubes, linea alba, and lower border of the four inferior ribs. Along the upper three-fourtlis of the linea semilunaris, the apo- neurosis of the internal oblique separates into two lamellae, which pass one in front, the other behind the rectus muscle to the linea alba, where they are inserted ; the former of these unites with the aponeurosis of the external oblique, and the latter with that of the transversalis. Along the lower fourth of the linea semilunaris, the aponeurosis does not divide, but passes in front of the rectus. The lowest fibres of the internal oblique are inserted into the crest and pectineal line of the pubes in common with those of the trans- versalis muscle. Hence the tendon of this insertion is called the conjoined tendon of the internal oblique and transversalis. This tendon is situated directly behind the external abdominal ring, and serves to strengthen what would otherwise be a weak point in the abdomen. Sometimes the tendon is insufficient to resist the internal pressure, and is forced through the external ring ; it then forms the distinctive covering of direct inguinal hernia. Nerve-supply.—Ilio-inguinal and ilio-hypogastric of first lumbar, and anterior branches of lower intercostal nerves. The spermatic cord passes beneath the arched border of the internal oblique muscle, between it and Poupart’s ligament. The interval between this lower border and Poupart’s ligament is there- fore called the spermatic or inguinal canal. During its passage some fibres are given off from the lower border of the muscle, which accompany the cord downwards to the testicle, and form loops around it; this is the cremaster muscle. The CREMASTER, considered as a distinct muscle, arises from the middle of Poupart’s ligament, and forms a series of loops upon the spermatic cord. A few of its fibres are inserted into the tunica vaginalis ; the rest ascends along the inner side of the cord, to be inserted, with the conjoined tendon, into the crest of the pubes in front of the sheath of the rectus. Where the muscle spreads out over the tunica vaginalis and spermatic cord it receives the name of cremasteric fascia. Relations.—The internal oblique is in relation by its external surface with the external oblique, latissimus dorsi, spermatic cord, 290 ABDOMINAL MUSCLES. and external abdominal ring. By its internal surface with the transversalis muscle, fascia transversalis, internal abdominal ring, and spermatic cord. By its lower and arched border with the spermatic cord ; forming the upper boundary of the inguinal canal. Nerve-supply.—The genital branch of the genito-crural nerve. Dissection.—The internal oblique muscle is to be removed by making an incision from the anterior superior spine of the ilium horizontally inwards to the edge of the rectus, and another at right Fig. 203.—Lateral view of the trunk, showing its muscles, particularly the transversalis abdominis. 1. Costal origin of the latissimus dorsi. 2. Serratus magnus. 3. Upper part of the external oblique, divided in the direction best calculated to show the muscles beneath without inter- fering with its indigitations with the serratus magnus. 4. Two of the external intercostal muscles. 5. Two of the internal intercostals. 6. Transversalis. 7. Its posterior aponeurosis. 8. Its anterior apo- neurosis, forming the posterior layer of the sheath of the rectus. 9. Lower part of the left rectus with the aponeurosis of the transversalis passing in front. 10. Right rectus muscle. 11. Arched opening left between the lower border of the transversalis muscle and Poupart’s ligament through which the sper- matic cord and oblique inguinal hernia pass. 12. Tensor vagina- femoris, gluteus medius and maxi- mus invested by fascia lata. angles to this, near the margin of the latter muscle, to the ribs ; the muscle is then to he separated from its anterior connections and turned backwards. Some degree of care will be required in per- forming this dissection, from the difficulty of distinguishing between this muscle and the one beneath. A thin layer of connective tissue is all that separates them for the greater part of their extent. Near the crest of the ilium the deep circumflex iliac artery ascends between the two muscles, and forms a guide to their separation ; but just above Poupart’s ligament they are so closely united that separation is impossible. TRANSVERSALIS. Tlie TRANSVERSALIS is the internal tiat muscle of the abdo- men, and is transverse in the direction of its fibres, as implied in its name. It arises from the outer third of Poupart’s ligament, from the anterior two-tliirds of the internal lip of the crest of the ilium ; from the spinous and transverse processes of the lumbar vertebrae through the medium of the aponeurosis, and from the inner surface of the six inferior costal cartilages, interdigitating with the fibres of the diaphragm. The superior fibres, proceeding from the cartilage of the seventh rib, are inserted into the ensiform cartilage ; the inferior fibres, proceeding from Poupart’s ligament, curve down- wards to be inserted by means of a tendinous expansion common to it, and the internal oblique, the conjoined tendon, into the crest of the pubes and pectineal line ; while the fibres intermediate between these points terminate near the outer border of the rectus in an apo- neurosis, which is continued onwards to the linea alba. The upper portion of the aponeurosis, closely united with the posterior lamella of the aponeurosis of the internal oblique, assists in forming the posterior wall of the sheath of the rectus, while the inferior portion, commencing at a point midway between the umbilicus and pubes, is continued with the undivided aponeurosis of the internal oblique in front of the rectus. Relations.—By its external surface with the internal oblique, the internal surface of the six lower ribs, and internal intercostal muscles. By its internal surface with the transversalis fascia, which separates it from the peritoneum, with the psoas magnus, the lower part of the rectus, and pyramidalis. The spermatic cord and oblique inguinal hernia pass beneath the lower border, but have no direct relation with it. The upper border is continuous with the diaphragm and triangularis sterni. Nerve-supply.—Anterior branches of lower intercostals. Lumbar Fascia.—The posterior aponeurosis of the transversalis divides into three lamellar, anterior, middle, and posterior, which constitute the fascia lumborum. The anterior lamella, thin and membranous, is attached to the base of the transverse processes of the lumbar vertebrae ; the middle lamella, of considerable thickness, to their apices ; the posterior layer receives the posterior aponeurosis of the internal oblique, and is attached to the spines of the lumbar vertebrae ; near the border of the erector spinae, it becomes united with the aponeurosis of the latissimus dorsi and serratus posticus inferior. Between the anterior and middle lamella is lodged the quadratics lumborum ; and between the middle and posterior layer, the erector spinae and multifidus spinae, which are thus furnished with aponeurotic sheaths. The anterior layer is attached above to the lower margin of the last rib and forms the ligamentum arcuatum externum. Dissection.—To dissect the rectus muscle, its sheath should be opened by a vertical incision extending from over the cartilages of the lower ribs to the front of the os pubis. The sheath may then be dissected off and turned aside ; this is easily done excepting at 291 MUSCLES OF THE ABDOMEN. 292 the linete transversal, where a close adhesion exists between the muscle and the external wall of the sheath. The RECTUS ABDOMINIS arises by a double tendon from the front and crest of the os pubis, and is inserted by three broad digitations into the outer surfaces of the cartilages of the fifth, sixth, and seventh ribs. It is traversed by several tendinous in- tersections, called lineal transversal (inscriptiones tendineaj). One of these is situated at the umbilicus, one over the ensiform cartilage, Fin. 204.—Transverse section through the abdominal walls, showing the arrangement of muscles and tendons. 1. A lumbar vertebra. 2. Psoas magnus muscle. 3. Quad- ratic lumborum. 4. Erector spinae. 5. Lumbar aponeurosis. 6. Latissimus dorsi. Between 5 and 6 the serratus posticus inferior is seen. 7. External oblique. 8. Internal oblique. 9. Transversalis. 10. Rectus abdominis. 11. Insertion of the lumbar aponeurosis into the spine of the lumbar vertebra. 12. Lumbar aponeurosis dividing into three layers. 13. The figure is placed on the quadratus lumborum, and has above it the anterior layer of the lumbar aponeurosis, and below it the middle layer. 14. Peritoneum where it covers the kidney. 15. Shows the mode of union of the tendons in the formation of the sheath of the rectus. and one midway between these points; when a fourth exists, it occurs below the umbilicus. They frequently do not involve the whole thickness of the muscle. Nerve-supply.—The ilio-hypogastric and anterior branches of intercostal nerves. The PYRAMIDALIS arises from the crest of the os pubis in front of the rectus, and is inserted into the linea alba at about mid- way between the umbilicus and pubes. It is enclosed in the sheath with the rectus, and rests against the lower part of that muscle ; it is sometimes absent. SHEATH OF THE RECTUS. 293 Nerve-supply.—The ilio-hypogastric nerve. The rectus may now be divided across the middle, and the two ends drawn aside for the purpose of examining the mode of con- struction of its sheath. Sheath of the Rectus.—This is formed, in front, for the upper three-fourths of its extent, by the aponeurosis of the external oblique Fig. 205.—Dissection of the lower part of the abdominal wall from within, the peritoneum having been removed, a. External iliac artery, b. Deep epigastric artery, c. Lower edge of the posterior part of sheath of rectus (fold of Douglas). d. Conjoined tendon in the triangle of Hesselbach. e. Posterior surface of rectus. /. Fascia transversalis. g. Vas deferens, h. Spermatic vessels, i. Obliterated hypogastric artery, k. Lymphatics of crural ring. 1. Internal abdominal ring. m. Urachus, n. Bladder. and anterior lamella of the internal oblique ; behind by the posterior- lamella of the internal oblique and aponeurosis of the transversalis. Midway between the umbilicus and the pubes, the posterior wall of the sheath terminates in a thin curved margin (.semilunar fold of Douglas), the aponeurosis of the three muscles passing, below this point, altogether in front of the rectus. Contents of the Sheath.—These are the rectus and pyramidalis muscles ; deep epigastric, superior epigastric, and terminal twigs of 294 MUSCLES OF THE ABDOMEN. the abdominal intercostal vessels ; anterior cutaneous branches of the intercostal nerves, and lymphatic vessels. Fascia Transversalis {abdominal fascia).—This is a thin fibrous membrane which lines the inner surface of the transversalis muscle and the other structures which form the abdominal wall where that Flo. 206.—Dissection of the inguinal canal, a. External oblique (turned down). 6, b. Internal oblique, c. Transrersalis. d. Conjoined tendon, e. Rectus, with sheath opened. /. Fascia transversalis. g. Triangular fascia, h. Cremaster. Infundibular fascia. muscle is absent. It is continuous behind with the iliac, and below with the pelvic fascia. It is strong and tough at the lower part of tin* abdomen, especially where the sheath of the rectus is deficient; but at the upper, where it is continued on to the diaphragm, it is little more than loose areolar tissue. In the centre it lines the back part of the sheath of the rectus, and where that is absent lines the rectus muscle and is attached to the crest of the pubis. At the sides it is attached to the inner lip of the crest of the ilium and along the whole length of Poupart’s ligament, where it is connected to the fascia lata, and for the outer half of the ligament to the iliac fascia which joins it behind. The union of these three fascia? takes place rather under than in Poupart’s ligament, which could therefore be cut away, leaving them connected together as a firm fibrous cord, to which is given the name of deep crural arch. At the inner half of Poupart’s ligament it is prolonged into the thigh, forming the anterior part of the sheath of the femoral vessels, as the posterior part is formed of a similar prolongation of the iliac fascia. The internal abdominal ring is an opening in this fascia situ- ated about half-way between the anterior superior spine of the ilium and the symphysis of the pubis, and half an inch above Poupart’s ligament. It is oval in form, the lower edge being strong, the upper thin and weak. Through this opening the sper- matic cord in the male passes to the testicle, and the round liga- ment of the uterus in the female to its insertion over the pubis. From the edges of the ring a funnel-shaped tube of transversalis fascia is given off which surrounds the structures forming the sper- matic cord. This is the infundibuliform fascia, sometimes called the fascia propria of the cord. The internal abdominal ring, there- fore, is simply the funnel-shaped mouth of this tube, and it is situated immediately external to the deep epigastric artery round which the spermatic cord turns in its passage from the abdomen to the scrotum. Inguinal Canal.—The spermatic or inguinal canal, which in the normal condition of the abdominal parietes serves for the passage of the spermatic cord in the male, and the round ligament with its vessels in the female, is about one inch and a half in length. It is bounded, in front, by the aponeurosis of the external oblique muscle and a few fibres of the internal oblique and cremaster : behind, by the transversalis fascia, the conjoined tendon of the internal oblique and transversalis, and triangular fascia ; above, by the arched border of the internal oblique and transversalis; beloiv, by the grooved border of Poupart’s ligament and the upper surface of Gimbernat’s ligament; and at each extremity by one of the abdominal rings, the internal ring at the inner, the external ring at the outer extremity. These relations may be more distinctly illustrated by the following plan :— INGUINAL CANAL. Above. Lower border of internal oblique and transversalis. T ( . njron . Aponeurosis of ex- ternal oblique, fibres of internal oblique and cremaster. Behind, Transversalis fascia. Conjoined tendon of illteJnal obiique and transversalis. Triangu- lar fascia. Inguinal canal. Below. Grooved border of Poupart's ligament. Gimbernat’s ligament. 296 SURGICAL ANATOMY OK INGUINAL HERNIA. SURGICAL ANATOMY OF INGUINAL HERNIA. Inguinal hernia is of two kinds, oblique and direct. In OBLIQUE INGUINAL HERNIA the intestine follows the same course as is pursued by the testicle in its descent, and obtains the same coverings as that organ. It escapes from the cavity of the abdomen into the spermatic or inguinal canal, through the internal abdominal ring, pressing before it a pouch of peritoneum which constitutes the hernial sac, and distending the infundihuliform pro- cess of the transversalis fascia. After emerging through the internal abdominal ring it pusses firstly beneath the lower and arched border of the internal oblique muscle ; and then through the external abdo- io. 207.—Diagram of a common scro- tal hernia, show- ing the relation of the sac to the tunica vaginalis testis. Fig. 208.—Diagram of a congenital hernia, the sac being con- tinuous with the tunica vaginalis tes- tis. Fig. 209.— Diagram of an infantile hernia, showing the tunica vaginalis prolonged in front of the sac. minal ring, in the aponeurosis of the external oblique. While pass- ing beneath the lower border of the internal oblique it obtains the cremaster muscle ; and on escaping' at the external abdominal ring, receives the intercolumnar or spermatic fascia. So that the cover- ings of an oblique inguinal hernia, after it has emerged through the external abdominal ring, are, from the surface to the intestine, the— Iii tegument, Superficial fascia, Intercolumnar fascia, Cremaster muscle, Transversal is, or infundihuliform fascia, Retro-]leritoneal fat, Peritoneal sac. SURGICAL ANATOMY OF INGUINAL HERNIA. 297 There are three varieties of oblique inguinal hernia : common, congenital, and infantile. Common oblique hernia is that which has been described above. Congenital hernia results from the non-closure of the pouch of peritoneum carried downwards into the scrotum by the testicle, during its descent in the foetus. In consequence of this defect, the intestine at some period of life is forced into the peritoneal canal, and descends through it into the tunica vaginalis, where it lies in contact with the testicle ; so that congenital hernia has no proper sac, but is contained within the tunica vaginalis. The other coverings are the same as those of common inguinal hernia. In the female, congenital hernia descends into the canal of Nuck. Infantile hernia is that form of protrusion in which the pouch of peritoneum forming the tunica vaginalis is only partially closed. The connection with the abdomen is completely closed at the inguinal canal, but the rest of the tube remains in its original state, and when a hernia makes its way into the scrotum it lies behind the en- closed tunica vaginalis. So that the surgeon, iii operating upon this variety, requires to divide three layers of serous membrane ; the first and second layer being those of the tunica vaginalis, the third the true sac of the hernia. A variety of this form is called encysted hernia ; in it, the hernial sac is invaginated into the incompletely closed tunica, as shown in Fig. 210. The surgeon has, therefore, to divide two layers of peritoneum before he reaches the bowel. DIRECT INGUINAL HERNIA has received its name from passing directly through the external abdominal ring, and forcing before it the opposing parietes. This portion of the wall of the abdomen is strengthened by the conjoined tendon of the internal oblique and transversal is, which is pressed before the hernia, and forms one of its investments. Its coverings, therefore, are the— Fig. 210.—Encysted hernia, Integument, Superficial fascia, Intercolumnar fascia, Conjoined tendon, Transversalis fascia, Retro-peritoneal fat, Peritoneal sac. Direct inguinal hernia differs from oblique, firstly, in never attain- ing the same bulk, in consequence of the resisting nature of the conjoined tendon and transversalis fascia ; secondly, in its having a tendency to protrude from the middle line rather than towards it. Thirdly, in making for itself a new passage through the abdominal parietes, instead of following a natural channel; and fourthly, in the relation of the neck of its sac to the epigastric artery ; that vessel lying to the outer side of the opening of the sac of direct hernia, and to the inner side of that of oblique hernia. The direct hernia passes through a triangular space, bounded on the outer side by the deep epigastric artery, on the inner by the edge of the rectus muscle, and below by Poupart’s ligament ; this space is called the triangle of Hesselbach. All the forms of inguinal hernia are designated scrotal, when they have descended into the scrotum ; the oblique inguinal is most fre- quently found in this situation, from its following the course of the spermatic cord. MUSCLES OF THE ABDOMEN. MUSCLES OF THE POSTERIOR WALL OF THE ABDOMEN, ANI) DIAPHRAGM. Dissection.—The next two muscles can be examined only when the viscera of the abdomen are removed. To see the quadratus lumborum, it is also necessary to divide and draw aside the psoas muscle and the anterior lamella of the posterior aponeurosis of the transversalis. The QUADRATUS LUMBORUM will be seen to consist of two portions :—one, the externalaridity from the ilio-lumbar ligament and adjoining part of the crest of the ilium for two inches in extent, and inserted into the apices of the transverse processes of the four upper lumbar vertebrae (sometimes also last dorsal) and last rib ; the other, the internal and anterior portion, arises by tendinous slips from the transverse processes of the three or four lower lumbar vertebrae, and passes upwards to be inserted into the lower border of the last rib. I f the muscle be cut across or removed, the middle lamella of the aponeurosis of the transversalis will be seen, attached to the apices of the transverse processes; the quadratus being en- closed between the two lamellae as in a sheath. Relations.—Enclosed in the sheath formed by the aponeurosis of the transversalis muscle, it is in relation, in front, with the kidney, colon, psoas magnus, and diaphragm. Behind, but also separated by its sheath, with the erector spinae. Nerve-supply.— Anterior branches of the lumbar nerves. The PSOAS PARVUS is a small and infrequent muscle which arises from the last dorsal and first, lumbar vertebra and from the intervertebral substance between them, and terminates in a long slender tendon which expands inferiorly and is inserted into the pectineal line and eminence. The tendon is continuous by its outer border with the iliac fascia. Relations.—It rests on the psoas magnus, and is covered in by the peritoneum ; superiorly it passes beneath the ligamentum areuatum internum of the diaphragm. Nerve-supply.—Branches of the lumbar plexus. DIAPHRAGM. 299 DIAPHRAGM.—To obtain a good view of this important inspiratory muscle, the peritoneum should be dissected from its under surface. It is a transverse muscular septum between the thorax and abdomen, and is composed of two portions, thoracic and lumbar. The thoracic portion arises from the ensiform cartilage by a distinct slip and from the internal surface of the six inferior ribs, interdigitating with the transversalis. The fibres converge to be inserted into the central tendon. A triangular interval exists between the sternal and costal portion of the muscle at each side, closed by a few irregular muscular fibres, some connective tissue, and bv the serous membranes of the cavity of the chest and abdomen. A protrusion of any portion of the contents Fig. 21 i. The dia- phragm viewed from the front, showing its upper or thoracic surface, i, i. The lateral segments of the thoracic portion; arising from 2, 2, The cartilages of the ribs ; and inserted into 3, The central tendon. The right segment is seen to be higher than the left. 4. The fasci- culus which arises from the ensiform cartilage. 5, 5. La- teral leaflets of the central tendon. 6. Opening for the in- ferior vena cava. 7. The oesophagus. 8. The thoracic aorta. 9. The abdominal aorta. 10. The tendon of the right crus of the diaphragm : that of the left is seen immediately above on the lumbar vertebrae, n, n. The psoas muscles. of tlie abdomen through this opening constitutes phrenic or dia- phragmatic hernia. The lumbar portion consists of a right and left lateral half (crura); each of which is composed of three smaller pillars, inter- nal, middle, and external. The crura arise from the front and lateral aspect of the bodies of the first, second, and third lumbar vertebrae, from the intervertebral substance between the first, second, third, and fourth, from the transverse process of the first, ligamentum arcuatum internum and externum, and last rib. The left crus is shorter than the right by the breadth of a vertebra, and does not advance so far forward on the front of the vertebral column. The crura are inserted into the whole length of the posterior border of the central tendon. The origin of the crura takes place by a strong tendon, from which and from the other points of attachment muscular fibres proceed. The internal pillar of the crus is its anterior fasciculus, which pro- 300 DIAPHRAGM. ceeds from the third lumbar vertebra ; the middle jrillar, smaller than the others, proceeds from the second vertebra ; the external pillar, the largest of the three, from the first lumbar vertebra, liga- menta arcuata, and last rib. The internal pillars approach each other as they ascend, the arched interval between them being the aortic opening ; their internal fibres, consisting of several fasciculi, cross each other in front of the aortic opening and form the lateral boundaries of another opening of elliptical shape (oesophageal), and are then lost in the central tendon. In the decussation between the Flf). 212.—Abdominal side of the dia- phragm. i, 2,3. The thoracic portion ; figure 1 rests on the central leaflet of the tendinous centre; figure 2 on the left or smallest leaflet; figure 3 on the right leaflet. 4. Fasci- culus from the en- siform cartilage; a small triangular space is left on either side of the fasciculus. 5. Liga- mentum arcuatum externum of the left side. 6. Liga- mentum arcuatum internum. 7. A small arched open- ing occasionally found, throug h which the lesser splanchnic nerve passes. 8. Tendon of the right crus. 9. Fourth lumbar vertebra. 10. Ten- don of the left crus. 11. Aortic opening occupied by the aorta. 12. Portion of the (esophagus issuing through the oesophageal opening. 13. Opening for the inferior vena cava, in the tendinous centre of the diaphragm. 14. Psoas inagnus passing beneath the ligamentum arcuatum internum ; it lias been removed on the opposite side to show the arch more distinctly. 15. Quadratus lumborum passing beneath the ligamentum arcuatum externum ; this muscle has also been removed on the left side. 16. Transverse processes of lumbar vertebrae, and intertransverse muscles. aort ic and oesophageal opening the til ires of the right internal pillar are generally the most superficial. Muscular fibres are commonly found passing from the upper surface of the diaphragm on to the left side of the pericardial sac (Forbes). Between the lumbar and costal portion of the diaphragm at each side there is often a triangular interval like that between the costal and sternal portion, closed only by areolar tissue and the serous membranes of the two cavities. The ligamentum arcuatum internum is a tendinous arch thrown across the upper part of the psoas muscle from the side of the body of the first lumbar vertebra to the apex of its transverse process, extending sometimes also to that of the second. Beneath this arch a psoas abscess emerges from the chest. The ligamentum arcuatum externum is a tendinous band ex- tended from the apex of the transverse process of the first lumbar vertebra to the lower border of the last rib. It forms an arch across the quad rat us lumborum, and is a thickened part of the sheath of that muscle derived from the posterior aponeurosis of the trans- versalis abdominis. The tendinous centre of the diaphragm is shaped like a trefoil leaf, of which the central leaflet points to the ensiform cartilage, and is the lai’gest; the lateral leaflets, right and left, occupy the corre- sponding portions of the muscle ; the right being the larger and rounded, the left smaller and lengthened in its form. The openings in the diaphragm are three: one, quadrilateral, in the tendinous centre, at the union of the right and middle leaflets, for the passage of the inferior vena cava and a branch of the phrenic nerve; a muscular opening of an elliptical shape formed by the internal pillars of the crura, the oesophageal, for the transmission of the oesophagus and pneumogastric nerves; a third, the aortic, formed by a tendinous arch thrown from the tendon of one crus to that of the other. The latter opening is the largest, lowest, and most pos- terior of the three ; it is bounded behind by the vertebral column, and gives passage to the aorta, vena azygos major, and thoracic duct. The great splanchnic nerve passes through the diaphragm between the internal and middle pillar of the crus; the lesser splanchnic nerve escapes between those fibres of the external pillar which pro- ceed from the ligamentum arcuatum internum. The sympathetic chain passes into the abdomen beneath the ligamentum arcuatum internum, and the vena azygos minor passes from the abdomen to the thorax through the left crus of the diaphragm. The diaphragm forms a dome, the convexity of which is directed towards the thorax and the concavity towards the abdomen; the right half rises to a higher level than the left, in consequence of being pushed upwards by the liver, and the central leaflet of the tendon is lower than the top of either half of the dome. During life, the level of the diaphragm varies with respiration and with the condition of the organs ; after death the top of the right half of the dome reaches to about a level with the lower border of the fourth rib, the left half to the upper edge of the fifth rib, and the central leaflet corresponds to the junction of the xiphoid cartilage with the sternum. Relations.—By its superior surface with the pleurae, pericardium, heart, and lungs. By its inferior surface with the peritoneum ; on the left with the stomach and spleen ; on the right with the con- vexity of the liver; behind with the kidneys, supra-renal cap- sules, duodenum, and solar plexus. By its circumference with the ensiform cartilage, ribs, intercostal muscles, and vertebral column. Nerve-supply.—The phrenic nerve, derived from the third, fourth, and fifth cervical. DIAPfIRAGM. 301 ACTIONS OF ABDOMINAL MUSCLES AND DIAPHRAGM. 302 Actions of the Muscles of the Abdominal Wall and the Diaphragm.—The external oblique muscle, acting singly, draws the thorax towards the pelvis, and twists the body to llie opposite side. Both muscles, acting together, flex the thorax directly on the pelvis. rl'he internal oblique of one side draws the chest downwards and out- wards ; both together bend it directly forwards. Either transversalis muscle, acting singly, will diminish the size of the abdomen on its own side, and both together will constrict the entire cylinder of the cavity. The recti muscles Hex the thorax towards the pelvis, and, through the arrangement of their sheaths, combine with the oblique and transverse muscles in exercising pressure on the abdominal viscera. The absence of the posterior layer of the sheath of the rectus muscles below allows of direct pressure being brought to bear upon the bladder when full, and upon the uterus in partu- rition. The pyramidales are tensors of the linea alba. The ab- dominal are expiratory muscles, and chief agents in expulsion; by their action, the foetus is expelled from the uterus, the urine from the bladder, faeces from the rectum, bile from the gall-bladder, ingesta from the stomach and bowels in vomiting, ana mucus and irritating substances from the bronchial tubes, trachea, and nasal passages during coughing and sneezing. To produce these effects, they all act together. The quadratus lumborum draws the last rib downwards, and is an expiratory muscle ; it also serves to bend the vertebral column to one or the other side. The psoas parvus is a tensor of the iliac fascia, and, taking its fixed origin from below, may assist in Hexing the vertebral column forwards. The diaphragm is an inspiratory muscle, and the sole agent in tranquil inspiration. When in action, the muscle is drawn downwards, its plane being rendered oblique from the level of the ensiform cartilage to that of the upper lumbar vertebra. During relaxation it is convex, and encroaches considerably on the cavity of the chest, particularly at the sides, where it corresponds with the lungs. It assists the abdominal muscles powerfully in expulsion, every act of that kind being preceded or accompanied by inspiration. Spasmodic action of the diaphragm produces hiccough and sobbing, and its rapid alternation of contraction and relaxation, combined with laryngeal and facial movements, laughing and crying. The muscles of the perineum are situated in the outlet of the pelvis, and consist of two groups, one of which belongs especially to the organs of generation and urethra, the other to the termination of the alimentary canal. To these may be added the muscles of the coccyx. The muscles of the perineal region in the male are the— MUSCLES AND FASCLE OF THE PERINEUM Bulbo-cavernosus, Ischio-cavernosus, Transversus perinei, Compressor urethrae, Sphincter ani, Levator ani, Coccygeus. PERINEAL FASCIA:. 303 Dissection.—To dissect tlxe perineum, the subject should be fixed in the position for lithotomy, that is, the hands should be bound to the soles of the feet, and the knees kept apart. Both of these means of preparation have for their object the full exposure of the perineum. And as this is a dissection which demands some degree of delicacy and nice manipulation, a strong light should be thrown upon the part. A large sound is to be introduced into the bladder, and a string, tied round the testicles, to be fixed to its handle. This will retain the sound in the bladder and put the perineum on the stretch. An incision is to be made from the point where the scrotum joins the perineum along the middle of the latter to the anterior edge of the anus, round each side of this, and from the posterior edge of it to the tip of the coccyx. This incision is to be supplemented by lateral ones carried from the anterior end of the first outwards on to the thigh and then backwards to a little beyond the level of the posterior margin of the anus, so as to include in its area the tuberosity and ramus of the ischium. The Haps are to be dissected back with great care, the integument alone being removed so as to expose the subcutaneous sphincter and the superficial fascia. After t lie fascia has been carefully dissected off and the perineal vessels and nerves turned aside, the muscles are brought into view. Perineal Fasciae.—The fascia? of the perineum are the superficial and the deep. The superficial fascia consists, as in other situations, of two layers, one lying next the skin and containing an abundance of fat, 1 he other more condensed lying in contact with the muscles. The superficial layer, or fatty layer, in the perineum is con- tinuous with the dartos of the scrotum, or areolar tissue of the labia majora, in front, with the superficial fascia of the thighs at each side, and with the superficial fascia covering the glutei maximi and with the coccyx behind. It differs in character and composition in different parts of the perineum ; thus at the back part it consists of tine granular fat which tills up the large space between the ischium and anus called the ischio-rectal fossa ; over the tuberosity of the ischium it becomes tough and stringy, and is formed by interwoven strands of fibrous tissue between which numerous small synovial bursae are found ; in the anterior part of the perineum, again, it is thin and membranous, the fat being replaced by unstriped muscular tissue, and is continued into the tunica dartos. The deep or membranous layer of the superficial fascia, or fascia of Colles, lies in close contact with the muscles and super- ficial vessels of the perineum, packing them into their places. On each side it is attached to the ramus of the ischium and pubes, and this attachment is continued forwards and outwards on to the fascia lata of the thigh, where it becomes continuous with the dee]? fascia of the groin. It is prolonged backwards as far as the transversalis perinei muscle, round the posterior border of which it turns to be united to the deep perineal fascia on which the muscle rests. At this point these two fasciae are blended together, and are then con- 304 TRIANGULA]! LIGAMENT. tinued backwards on tlie outer surface of the levator aid, to join the anal fascia. It is continued forwards to blend with the deep fascia of the penis. In the middle line it has on its deep aspect a septal prolongation, complete behind but incomplete in front, so that air or fluid injected beneath the fascia would fill up one side of the pouch which it forms, then passing forwards to where the septum is incomplete, would infiltrate the other side. The attachment of the membranous layer to the deep perineal fascia explains why an ex- travasation of fluid under that membrane could not pass back into Fio. 213.—The pubic arch and perineal fascia;. The corpora cavernosi and corpus spongiosum with the muscles which lie upon them, as well as the vessels and nerves, have been removed. 1, 1, 1. The deep layer of the superficial perineal fascia divided by a incision into three flaps ; the lateral flaps are turned over the ramus of the pubes and ischium at each side, to which they are firmly attached ; the posterior flap is continuous with the deep perineal fascia or triangular ligament. 2. The triangular ligament of the urethra. 3. Opening for the passage of the membranous portion of the urethra, previously to the entrance of the latter into the bulb. 4. Two projections of the triangular ligament corresponding with the position of Cowper’s glands. the posterior half of the perineum, but could find its way, as it often does, into the scrotum and up over the abdomen. Muscular Triangle.—The space between Codes’ fascia and the triangular ligament is occupied by the bulb of the urethra, corpus spongiosum, crura penis, bulbo-cavernosi, ischio-cavernosi and trans- versus perinei muscles, anterior and posterior superficial perineal nerves, superficial perineal and transverse perineal vessels, and a few lymphatic vessels. The deep perineal fascia or triangular ligament of the urethra is a strong aponeurotic sheet which is stretched across the inter-pubic arch. It is attached firmly to the sub-pubic ligament, and to the TRIANGULAR LIGAMENT. 305 ramus of the pubes and ischium. At the posterior border of the transversalis perinei muscle, it has attached to it the deep layer of the superficial fascia, and with it is prolonged hack on the levator ani muscle, as the anal fascia. At an inch and a half from the symphysis pubis, in the middle line, it is connected to the central tendinous point of the perineum. About an inch below the symphysis pubis it is pierced for the passage of the membranous portion of the urethra, which is contained between it and the parietal layer of the pelvic fascia behind. Immediately below the sub-pubic ligament the dorsal vein of the penis passes back through it to join the prostatic plexus, and on each side, a little in front of this, the pudic arteries pass through it to enter the corpora cavernosa penis. Between this liga- ment and the pelvic fascia are situated the compressor urethra; muscle, the internal pudic arteries, the arteries of the corpus cavernosum, dorsum of the penis and bulb, Cowper’s glands, the membranous part of the urethra, the dorsal vein of the penis, the dor- sal nerve, lymphatic vessels, and a plexus of veins. Sometimes the triangular ligament is described as consisting of two layers, anterior and posterior, the former being the deep perineal fascia, and the latter the layer of pelvic fascia passing across the pelvic arch. When the ligament is thus described, the structures above enumerated are said to he placed between the two layers of the triangular ligament. The BULBO-CAVERNOSI (accelerators urince) arise from a tendin- ous point in the centre of the perineum, and from the fibrous raphe of the two muscles. From this origin the fibres diverge like the barbs of a pen ; the posterior to be inserted into the triangular liga- ment ; the middle, to encircle the corpus spongiosum and meet on its upper side ; the anterior, to spread out on the corpus cavernosum at each side, and be inserted partly into its fibrous structure, and partly into the fascia on the dorsum of the penis. The posterior and middle insertions of these muscles are best seen by carefully raising one muscle from the corpus spongiosum and tracing its fibres. The ISCHIO-CAVERNOSUS {erector penis) arises from the tuberosity of the ischium and from the ramus of the pubes behind the extremity of the crus, and curves around the root of the penis ; to he inserted into the upper surface of the corpus cavernosum, where it is con- tinuous with a strong fascia which covers the dorsum of the organ, the fascia penis. Nerve-supply.—The perineal branch of the pudic nerve supplies the acceleratores urinse and the erector penis. Fig. 214.—Diagrammatic view of the anterior layer of the triangular ligament and the structures passing through it. 1. Process passing down to central tendinous point. 2. Triangular ligament. 3. Dorsal vein of penis. 4. Urethra. 5. Dorsal artery. 6. Artery of corpus caver- nosum. 7. Artery of bulb. 8. Duct of Cowper’s gland. 9. Internal pudic artery. 306 MUSCLES OF THE PERINEUM. The TRANSVERSUS PERINEI arises from the ramus of the ischium at each side, and is inserted into the central tendinous point of the perineum, where it is connected with the bulbo-cavernosus and sphincter ani. Occasionally the transversus perinei is of large size, and spreads out as it approaches the middle line so as to become fan-shaped. The posterior fibres are continuous with those of the Fig. 215—Muscles of the perineum, i. Bulbo-cavornosi; the figure rests on the corpus spongiosum penis. 2. Corpus cavernosum of one side. 3. Ischio-cavernosus of one side. 4. Transversus perinei of one side. 5. Muscular triangle, through which the triangular ligament is seen. 6. Sphincter ani; its anterior extremity cut off. 7. Levator ani of the left side; the deep space between the tuberosity of tiie ischium (8) and the anus, is the iseliio-rectal fossa ; the same fossa is seen'on the opposite side. 9. Spine of the ischium. 10. Left coccygeus muscle. The boundaries of the perineum are well exhibited in this engraving. muscle of the opposite side ; but the anterior are prolonged forwards upon the bulb and corpus spongiosum of the urethra. Nerve-supply.—The perineal branch of the pudic nerve. Dissection.—To dissect the compressor urethra?, the three preced- ing muscles should be removed, so as to render the glistening surface of the triangular ligament apparent. This ligament should then be carefully dissected away, and the corpus spongiosum penis divided through its middle, separated from the corpus cavernosum, and drawn forwards in order to put on the stretch the membranous por- tion of the urethra, with which tlie compressor muscles are con- nected. The compressor urethrae is, however, better seen in a dissection made from within the pelvis, after having turned down the bladder from its attachment to the os pubis, and removed a plexus of veins together with the pelvic fascia. The COMPRESSOR URETHRAE (constrictor urethrae membra- nacese), directed transversely across the perineum above the tri- angular ligament, arises from the ramus of the pubes and ischium, their point of union, and from the anterior ligament of the bladder Fig. 1.—SUPERFICIAL DISSECTION SHOWING THE VESSELS AND NERVES. H. Coccyx. I. Gluteus maximus. K. Levator ani. L. Triangular ligament. 1. Superficial perineal vessels and nerves. 2. Inferior hsemorrhoidal vessels and nerves. Fig. 2.—DISSECTION SHOWING THE MUSCLES. THE MALE PERINEUM. PLATE 21. A. Urethra. B. Bulbo-cavernosus. C. Central point of perineum. D. Ischio-cavernosus. E. Transversus perinei. F. Anus. G. Tuber ischii. PLATE 21. Fig. 2. Fir 1. SPHINCTER ANI. and prostate gland. Proceeding inwards it divides into two fan- sluiped fasciculi, superior and inferior, which embrace the mem- branous portion of the urethra, and are continuous with the muscle of the opposite side. The superior fasciculus is continued forwards to the junction of the crura penis, and backwards to the prostate gland ; on the upper surface of which it is spread out. The in- ferior fasciculus is attached to the bulb of the urethra in front, and extends to the prostate gland be- hind. The lowest fibres of this fasciculus are sometimes described as a separate muscle under the name of deep transversus perinei muscle. A third fasciculus, closely united with the two preceding, con- sists of circular fibres, which en- close and form a muscular sheath for the membranous part of the urethra, and are continuous pos- teriorly with the circular muscular fibres of the prostate gland. Under the name of Wilson’s muscle, a fourth fasciculus has been described as descending vertically from the body of the pubes, near the symphysis, to unite with the superior fasciculus of the compressor urethrae. Nerve-supply.—The perineal branch of the pudic. The SPHINCTER ANI is a thin and elliptical plane of muscle closely adherent to the integument, and surrounding the opening of the anus. It arises posteriorly in the superficial fascia around the coccyx, and by a fibrous raphe (called the ano-coccygeal ligament) from the apex of that bone ; it passes round the margin of the anus, and is inserted anteriorly into the tendinous centre of the perineum, and into the raphe of the integument, nearly as far forward as the commencement of the scrotum. The anterior fibres mingle with those of the bulbo-cavernosus, the outer ones pass into the levator ani, while some of the innermost fibres cross the median line and decussate with those of the opposite side. The SPHINCTER ANI INTERNETS is a muscular band embracing the extremity of the intestine, and formed by an aggregation of the circular muscular fibres of the rectum ; it is composed of unstriped muscle. Nerve-supply.—The sphincters are supplied by the anterior branch of the fourth sacral, and inferior hseinorrlioidal branch of the internal pudic. 307 Fig. 2x6.—Posterior view of tiie pubes, with part of bladder and urethra at- tached. i. Body of pubes. 2. Ramus. 3. Obturator interims muscle. 5. Por- tion of the fundus and neck of the bladder laid open. 6. Prostate gland. 7. Transverse fibres of the compressor urethrae, passing above the urethra. 8. Similar fibres passing beneath that canal. 308 MUSCLES OF THE PERINEUM. The central tendinous point of the perineum is situated in the middle line of the perineum, midway between the anus and hull) of the urethra. It forms the meeting-point of a number of the perineal muscles; these are the bulbo-cavernosus, transversus perinei, external sphincter ani, and levator ani muscles of the two sides. Dissection.—Part of the levator ani may be seen during the dis- section of the anal portion of the perineum by removing the fat from the ischio-rectal fossa. But to study the entire muscle, a lateral section of the pelvis must be made by sawing through the pubes a little to one side of the symphysis, separating the bones behind at the sacro-iliac symphysis, and turning down the bladder and rectum. The spine of the ischium should be cut off with the bone forceps or saw, so as to leave it in connection with the levator ani and pelvic fascia. The pelvic fascia is then to be carefully raised, beginning at the base of the bladder, and proceeding up- wards, until the whole extent of the muscle is exposed. The LEVATOR ANI is a thin plane of muscular fibres, situated at each side of the pelvis. The muscle arises from the inner surface of the os pubis near the pubic arch, from the base and upper border of the spine of the ischium, and between those points, from a ten- dinous arch which occupies the line of division of the pelvic fascia into parietal and visceral layers, and is called the white line. Its fibres descend to be inserted into its fellow of the opposite side be- neath the prostate gland, into the rectum, and behind the rectum into its fellow of the opposite side and the side of the extremity of the coccyx. Its anterior fibres are sometimes described separately, under the name of levator prostati. In the female this muscle has an additional insertion intotlie vagina. Relations.—By its external or perineal surface, with the anal fascia, by which it is separated from the ischio-rectal fossa ; with the fat in the ischio-rectal fossa, triangular ligament, sphincter ani, and posteriorly, gluteus maximus. By its internal or pelvic surface with the pelvic fascia, which separates it from the viscera of the pelvis and peritoneum. Its posterior border is continuous with the coccygeus muscle. Nerve-supply.—The anterior branch of the fourth sacral. The COCCYGEUS muscle, thin and triangular, arises from the pelvic surface of the spine of the ischium and lesser sacro-ischiatic ligament, and spreads out to be inserted into the side of the coccyx and lower part of the sacrum. Relations.—By its internal or pelvic surface with the cavity of the pel vis and rectum ; by its external surface with the lesser sacro- ischiatic ligament; and by its borders with the pyriformis behind, and levator ani in front. Nerve-supply.—The fourth and fifth sacral and coccvgeal nerves. FEMALE PERINEUM. -The muscles of the perineum in the female are the same as in the male, and have received analogous names. They are smaller in size, and are modified to suit the difference of form of the organs ; they are— MUSCLES OF THE FEMALE PERINEUM. Sphincter vaginae; Ischio-cavernosus, Transversus perinei, Compressor urethrae, Sphincter ani, Levator ani, Coccygeus. The SPHINCTER VAGINA corresponds to the bulbo-cavernosus of the male ; it arises from the tendinous centre of the perineum, where it is continuous with the sphincter ani and transversus Fig. 217.—Superficial muscles of female perineum. 1. Pubes. 2. Clitoris. 3. Ischio- cavernosus. 4. Vestibule. 5. Sphincter vagina;. 6. Urethra. 7. Transverse perineal muscle. 8. Bulb of vagina. 9. Obturator externus muscle. 10. Vagina. 11. Levator ani. 12. Gland of Bartholine. 13. Sphincter ani externus. 14. The perineal body. 15. Gluteus maxinms. 16. Anus. perinei; and passes forwards on each side of the entrance of the vagina, to be inserted into the corpus cavernosum clitoridis, a fasci- culus crossing over this structure so as to compress the dorsal vein of the clitoris. The ISCHIO-CAVERNOSUS (erector clitoridis) arises from the ramus of the ischium, and is inserted on each side into the crus clitoridis. It is in relation by its inner border with the sphincter vagina?. The TRANSVERSUS PERINEI is a small muscle arising on each 310 ACTIONS OF THE PERINEAL MUSCLES. side from tlie ramus of the ischium, and inserted into the central point of the perineum. The COMPRESSOR URETHRAE has the same origin and insertion, and exercises the same functions in the female as in the male. The SPHINCTER ANI and SPHINCTER ANI INTERNUS surround the lower extremity of the rectum, as in the male. The LEVATOR ANI is inserted into the side of the vagina and rectum. The COCCYGEUS is identical with the same muscle in the male. Nerve-supply.—These muscles are supplied by the same nerves as the corresponding muscles of the male perineum. Actions.—The bulbo-cavernosi being continuous at the middle line, and attached at each side to the triangular ligament by means of their posterior fibres, support the bulbous portion of the urethra, and acting forcibly, propel the semen, or the last drops of urine from the canal. The posterior and middle fibres contribute to the erection of the corpus spongiosum, by compressing the veins leaving the bulb ; and the anterior fibres assist in the erection of the entire organ by compressing the vena dorsalis, by means of their insertion into the fascia penis. The ischio-cavernosus spreads out on the dorsum of the organ into a membranous expansion (fascia penis), which compresses the dorsal vein during the action of the muscle, and especially after the erection of the organ has commenced. Erection of the penis results from the retention of the blood in the venous spaces of the corpora cavernosi and corpus spongiosum, that retention being brought about by the compression of the veins of those bodies by the bulbo-cavernosus and ischio-cavernosus muscles. The transverse muscles serve to steady the tendinous centre, that the muscles attached to it may obtain a firm point of support. The compressor urethra’, taking its fixed point from the ramus of the ischium at each side, can compress the urethra so as to close it completely, after the manner of a sphincter. The external sphincter, being a cutaneous muscle, contracts the integument around the anus, and by its attachment to the tendinous centre of the perineum and point of the coccyx, assists the levator ani in giving support to the opening during expulsive efforts. The contraction of this muscle is usually involuntary, but may be made more forcible at will. The internal sphincter contracts the extremity of the cylinder of the intestine. The use of the levator ani is expressed in its name ; it is the antagonist of the diaphragm and abdominal expulsory muscles, and serves to support the rectum and vagina during their expulsive efforts. Yielding to the propulsive action of the abdominal muscles, it enables the outlet of the pelvis to bear a greater force than a resisting structure, and, on the remission of such action, restores the perineum to its original form. Along with the coccvgeus it inverts the anal border of the rectum after its protrusion in defsecation. The coccygei muscles restore the coccyx to its natural position, after it has been pressed backwards during defaecation or parturition. PELVIC FASCIA. 311 PELVIC FASCIA. Dissection.—The pelvic fascia may be dissected in three different ways, and viewed from three different aspects ; thus, (i) it may be seen from above, by stripping the peritoneum from the wall of the pelvis and the surface of the bladder, and carefully removing the extra-peritoneal fat. Again, (2) it may be seen from below, by removing the fat and the lisemorrhoidal vessels and nerves from the ischio-rectal fossa. After the layer covering the levator ani Fig. 218.—Side view of pelvis, showing the line of section through the bone to display the pel- vic fascia, i. Ex- ternal cutaneous nerve. 2. Iliacus muscle. 3. Pou- part’s ligament. 4. Anterior crural nerve. 5. Psoas. 6. Femoral vessels. 7. Gluteal vessels and nerve. 8. Pyri- formis. 9. Great ischiatic nerve. 10. Pudic vessels and nerve, and nerve to the obturator interims. 11. Ob- turator internus. 12. Lesser ischiatic nerve. 13. Ischiatic artery. {anal fascia) and that lining the wall of the pelvis {obturator fascia) have been studied in this way, the levator may he separated from the rectum and turned down, when the fascia which lines its inner surface {rectal fascia) will he seen, and there will also be brought into view the ischio-rectal layer passing between the bladder and rectum. (3) To obtain a lateral view of the pelvic fascia a more elaborate dissection is required. The muscles attached to one side of the pubic arch and margin of the obturator foramen are to be completely removed, and also the obturator membrane. The spine of the ischium is to be cut through by means of bone pliers ; then 312 PELVIC FASCIA. the bone is to be sawn through above and below the acetabulum, by two cuts, the upper running from the upper margin of the obturator foramen to the upper part of the great sciatic notch, and the lower from the lower margin of the obturator foramen through the tubero- sity of the ischium into the lesser sciatic notch ; the line of section is shown in Fig. 218. The obturator interims may now be detached from adjacent structures, by grasping its tendon and gently drawing it upwards and forwards. The pelvic fascia is a strong fibrous layer situated beneath the peritoneum, forming a covering to the walls of the pelvis, and reflected from its walls on to the viscera. It corresponds in position in the pelvis to the fascia lining the abdominal wall (transversalis fascia), and with that covering the iliacus muscle in the iliac fossa (iliac Fig. 219.—Arrange- ment of pelvic fascia. 1. Symphysis pubis. 2. Bladder. 3. Pros- tate gland. 4. Vesi- cula seminalis. 5. Rectum. 6. Perineal body. 7. Bulb of urethra, a. Codes’ fascia, b. Anterior layer of triangular ligament. c. Pos- terior layer of tri- angular ligament. d. Pubo - prostatic ligament, e. Recto- vesical fascia, form- ing a sheath for the vesicula seminalis. /. Posterior true liga- ment of bladder, g. Anterior true liga- ment of bladder. fascia), but is not at any part directly continuous with the former fascia, and is connected with the latter only for about an inch of the back part of the pectineal line. The pelvic fascia is, for convenience of description, divided into a parietal and a visceral layer. The parietal layer of pelvic fascia is connected with the back part of the pectineal line, being there continuous with the iliac fascia; it then passes obliquely downwards and forwards, along the upper edge of the obturator interims muscle to the upper margin of the obturator foramen ; it here leaves the bone, and passing over the upper edge of the obturator muscle joins the obturator membrane, thus converting the groove on the under surface of the. pubic bone into a canal for the obturator vessels and nerve. Again reaching the bone, it descends still lower, being found at the middle line of the PELVIC FASCIA. body at the level of the lower border of the pubic symphysis. From this line of attachment, the parietal pelvic fascia passes down over the inner surface of the obturator interims to the ramus of the ischium and pubes and the greater and lesser sciatic ligaments, to all of which structures it is very firmly attached ; it is here known as the obturator fascia. Where the internal pudic vessels and nerve pass inside the tuberosity of ischium, this fascia forms a canal for them in conjunction with the falciform edge of the great sciatic ligament; this is called Alcock’s canal. Across the pubic arch the parietal layer is continued to form the so-called posterior layer of the triangular ligament; this portion is attached above to the sub-pubic ligament, on each side to the ramus of the pubes, and below is continuous with the triangular ligament (anterior layer). Traced backwards the parietal layer is found to clothe the pyri- Fig. 220.—Transverse section of the pelvis, seen from behind, showing the arrange- ment of the pelvic fascia. i. Bladder. 2. Vesicula seminalis of one side divided. 3. Rectum. 4. Iliac fascia, covering in the iliacus and psoas (5); and forming a sheath for the exter- nal iliac vessels (6). 7. Anterior crural nerve excluded from the slieatl). 8. Pelvic fascia. 9. Its ascend- ing layer, forming the lateral ligament of the bladder of one side, and a sheath to the vesical plexus of veins. 10. Recto-vesical fascia, n. Rectal fascia. 12. Levator ani. 13. Obturator interims, covered in by the obturator fascia, which also forms a sheath for the in- ternal pudic vessels and nerve (14). 15. Anal fascia investing the under surface of the levator ani. Figures 14, 15 are placed in the ischio-rectal fossa. formis muscle (fascia of the pyriformis) and sacral plexus, being pierced by the branches of the internal pudic artery ; it is here very thin and ill-defined, and, becoming more so as it passes backwards, is lost in the loose connective tissue and fat filling in the interval between the rectum and front of the sacrum. The visceral layer of the pelvic fascia is derived from the inner surface of the parietal layer along a line drawn from the inner surface of the body of the pubes to the spine of the ischium. Along this line the fascia is thickened and shining, hence it is known as the white line ; it gives attachment to the origin of the levator ani muscle. The visceral layer is reflected backwards from the symphysis pubis on tire upper surface of the prostate gland and neck of the bladder. This curved reflected fascia is named the an- PELVIC FASCIA. 314 terior true ligament of the bladder, or pubo-prostatic ligament, and as there is a pouch-like depression in the centre, dividing the fascia of one side from that on the other, each side rises up in a little curved ridge, so that there are two anterior ligaments. The space between the two contains, external to the fascia, the dorsal vein of the penis before it enters the prostatic plexus. At the sides of the pelvis the anterior ligaments are continued back into another part of the pelvic fascia, which is reflected inwards towards the bladder from the line of origin of the visceral layer. This begins as a strong white band, and is called the lateral ligament of the bladder ; it not only reaches the side of the bladder, but is continued over it, although it becomes very thin and is almost lost in the areolar tissue over the apex. If the lateral ligament be divided near its attachment to the bladder, there will be found beneath it another layer of fascia passing across the pelvis between bladder and rectum ; this is the recto- vesical fascia. As it crosses the pelvis it gives capsules to the prostate gland and vesiculae seminales, and forms a sheath which encloses the lower three inches of the rectum ; posteriorly, it only extends back as far as the posterior limit of the trigone of the Fig. 22i.—Dia- gram of the layers of pel- vic fascia, i. Pel vie fascia. 2. Obturator. 3. Lateral ligament. 4. Anal. 5. Rec- tal. 6. Recto- vesical. 7. Ischio-rectal fossa. Obturator internus. Levator ani. Lateral ligament of bladder. Capsule of pros-_ tate. Rectum (cut). Felvie fascia. Obturator fascia. Recto - vesical fascia. Anal fascia. Fig. 222.—Section of pelvis to show the pelvic fascia from the front. bladder, where it is attached to the anterior extremity of the recto- vesical pouch of peritoneum. Beneath this layer, a thin and ill- defined fascia passes on the inner surface of the levator ani and be- tween that muscle and the side of the rectum ; this is named the rectal fascia ; it is absent at the anterior border of the levator, where that muscle passes beneath the prostate gland. Still another layer of the visceral pelvic fascia is found, clothing the external surface of the levator ani; it is called the anal fascia; it is con- tinuous at its anterior extremity with the perineal fascia, and by its upper edge with the obturator fascia, and forms the inner boundary of the ischio-rectal fossa. The veins of the bladder form a large and important plexus (vesical plexus) at the side of the base of that organ, between the lateral ligaments and recto-vesical fascia ; this plexus is continuous with a similar plexus on the prostate (prostatic plexus), placed be- tween the pubo-prostatic ligaments and the capsule of the gland. MUSCLES AND FASCTAE OF THE UPPER EXTREMITY. MUSCLES AND FASCUE OF THE UPPER EXTREMITY. The superficial fascia of the upper extremity contains between its layers the superficial veins and lymphatics, and superficial nerves. The deep fascia is thin over the deltoid and pectoralis major muscle, but thick on the dorsum of the scapula, where it binds down the infra-spinatus muscle. It is attached to the clavicle, coracoid process, acromion process, and spine of the scapula, and forms separate sheaths for all the muscles of the scapula and shoulder. In the upper arm it is somewhat stronger, receives fibres from the lower border of the tendons of the pectoralis major and latis- simus dorsi, as also from the costo-coracoid membrane and deltoid, and forms an anterior and posterior sheath for the muscles lying in front of and behind the humerus. It is attached to the condylar ridges, by means of the internal and external intermuscular septum, and is inserted interiorly into the two condyles, the ole- cranon, and posterior border of the ulna, being continuous between these points with the fascia of the forearm. Besides forming separate sheaths for the muscles, the anterior portion of the brachial fascia gives a sheath likewise to the brachial vessels and median nerve. The intermuscular septa serve to separate the muscles on the back from those on the front of the upper arm, and also give an increased area for the attachment of those muscles. The external septum is pierced from behind forwards by the musculo-spiral nerve and superior profunda artery ; the internal is pierced from before backwards by the ulnar nerve and inferior profunda and anastomotica arteries. Axillary Fascia.—A strong layer of deep fascia stretches across the base of the axillary space. It is continuous in front with the fascia which encloses the pectoralis muscle, and slopes downwards and backwards to join the fascia covering the latissimus dorsi; on its upper surface it is joined by a layer descending from the pec- toralis minor, and by this means is drawn upwards so as to produce ANNULAR LIGAMENTS. the hollow of the arm-pit. Near the chest wall it is pierced by numerous lymphatic vessels, and on the outer side it is continuous with the sheath of the axillary vessels and with the deep fascia of the arm. The deep fascia of the forearm is strong, and at the bend of the elbow is augmented in thickness by a broad band, which is given off from the inner side of the tendon of the biceps (bicipital fascia). It is firmly attached to the olecranon process, to the ulna, and to tin* prominent points about the wrist, forms sheaths for the muscles and vessels, gives origin to some of the fibres of the muscles, and is pierced a little above the wrist by the tendon of the palmaris longus. At the wrist the transverse fibres form the anterior and posterior annular ligament. The anterior annular ligament is a narrow band of fibres attached externally to the scaphoid, and internally to the pisiform bone and tendon of the flexor carpi ulnaris ; it is continuous above with the dee]) fascia of the forearm, and below with the palmar fascia. It is connected with the tendons of the palmaris longus and flexor carpi ulnaris, and gives origin to certain of the muscles of the thumb and little finger. The ulnar vessels and nerve, and the cutaneous branches of the median nerve, lie superficially to it. The ligament is pierced by the tendon of the flexor carpi radialis, and forms with the carpal bones a canal which is lined by synovial mem- brane, and gives passage to the tendons going to tiie fingers. The synovial sheath is divided into a large and a small compartment, the former transmitting the flexor sublimis and profundus tendons and the median nerve, the latter enclosing the tendon of the flexor longus pollicis. The posterior annular ligament is an oblique band about half an inch in breadth, extending from the lower end and styloid process of the radius to the cuneiform and pisiform bone at the border of the carpus. It is continuous above with the fascia of the forearm, below with the thin fascia of the dorsum of the hand, and sends processes inwards to be attached to the bones and form sheaths for the extensor tendons. There are six of these sheaths, the first on the radial side giving passage to the extensor ossis metacarpi and extensor primi internodii pollicis ; the second, to the extensor carpi radialis longior and brevior ; the third, to the extensor secundi internodii; the fourth, to the extensor indicia and extensor com- munis digitorum ; the fifth, which is placed between the two bones, to the extensor minimi digiti ; and the sixth, situated on the ulna, to the extensor carpi ulnaris. The tendons in passing through these sheaths are each provided with a synovial bursa. On the back of the hand there are two fasciae, superficial and deep. The superficial dorsal fascia is thin and covers in the extensor tendons; it is attached laterally to the metacarpal bones of the index and little finger, and is continuous above with the posterior- annular ligament. The deep dorsal fascia is stretched across the metacarpal spaces and covers in the interossei muscles. ANTERIOR THORACIC REGION. The palmar fascia is divided into three portions. A central portion, which occupies the middle of the palm, and two lateral portions, which are thin and enclose the muscles of the borders of the hand, being continuous with the dorsal fascia. The central portion is strong and tendinous : it is narrow at the wrist, where it is attached to the annular ligament and receives the insertion of the tendon of the palmaris longus, and broad over the heads of the metacarpal bones, where it divides into four processes, each of which subdivides to embrace the root of the corresponding finger. These processes are attached at the middle line to the sheath of the tendons, and at the side of each finger to the lateral and transverse ligament. The fascia is strengthened at this point of division by strong fasciculi of transverse fibres ; the arched interval caused bv the bifurcation of each slip gives passage to the tendons of the flexor muscles, while the greater arches between the fingers transmit the digital vessels and nerves, and lurnbricalis muscles. The palmar fascia is intimately adherent to the skin of the palm by numerous fine fibrous bands, and gives attachment by its inner margin to the palmaris brevis muscle. Beneath the skin of the fingers some tendinous bands are found, which are probably the representatives of the deep fascia. They have been described by Cleland under the name of phalange o- cutaneous ligaments, and pass from the sides of the base of the first phalanx of each finger to the skin on the back of the second, and from the sides of the base of the second phalanx to the deep surface of the skin forming the pulp of the finger. Dissection.—Make an incision along the line of the clavicle, from the upper part of the sternum to the acromion process, and thence down the arm as far as the level of the lower border of the latis- simus dorsi; a second carried transversely outwards from the base of the ensiform cartilage to the posterior border of the axilla ; and connect the two by a third, carried longitudinally along the middle of the sternum. The integument and superficial fascia are to be dissected separately from off the fibres of the muscle, and always in the direction of their course. For this purpose the dissector, if he have the right arm, will commence with the lower angle of the Hap ; if the left, with the upper angle. He will thus expose the pectoralis major muscle in its whole extent. Pectoralis major, Pectoralis minor, Subclavius. The PECTORALIS MAJOR arises from the sternal half of the clavicle, from half the sternum its whole length, from the cartilages of all the true ribs, excepting the first and last, and from the apo- neurosis of the external oblique muscle of the abdomen. From this extensive origin the fibres converge to lie inserted by a broad and folded tendon into the external bicipital ridge of the humerus. Anterior Thoracic Region. The pectoral is major admits of division into three portions, clavi- cular, sternal, and costal; the two former are separated from eacli other by a well-marked areolar interspace ; the latter is distin- guished not only by its origin, but also by forming a fold beneath the sternal portion, and lying behind it at its insertion. At the latter point the three portions are superimposed, the clavicular being in front, the sternal next, the costal behind ; the clavicular portion being prolonged at its insertion to'tlie lower extremity of the bicipital ridge, the costal portion to its upper end. The clavicular portion, which arises highest up, is inserted lowest down, and the costal portion which arises lowest is inserted highest on the humerus. Relations.—By its external surface with the fibres of origin of the platysma myoides, mammary gland, superficial fascia, and in- tegument. By its internal surface, on the thorax, with the clavicle, sternum, costal cartilages, intercostal muscles, subclavius, pectoralis minor, and serratus magnus ; in the axilla, with the axillary vessels and glands. By its external border with the deltoid, from which it is separated above by an areolar interspace lodging the cephalic vein and descending branch of the tlioracico-acromialis artery. Its lower border forms the anterior boundary of the axillary space. Nerve-supply.—External and internal anterior thoracic branches of the brachial plexus. Dissection.—The pectoralis major is to be removed by dividing its fibres along the lower border of the clavicle, and then carrying the incision perpendicularly downwards, parallel to the sternum, and at about three inches from its border. Divide some loose areolar tissue, and several small branches of the thoracic arteries, and reflect the muscle outwards. We thus bring into view a region of con- siderable interest, in the middle of which is situated the pectoralis minor. The PECTORALIS MINOR arises by three digitations from the front, upper border and outer surface of file third, fourth, and fifth ribs near their cartilages, and from the intercostal fascia ; and is inserted by a broad tendon into the anterior border and upper surface of the coracoid process of the scapula. It is closely united at its insertion with the coraco-brachialis. Relations.—By its anterior surface with the pectoralis major and superior thoracic vessels and nerves. By its posterior surface with the ribs, intercostal muscles, serratus magnus, axillary space, and axillary vessels and nerves. Its upper border forms the lower boun- dary of a triangular space, bounded above bv the costo-coracoid membrane, and internally by the ribs ; in this space are found the axillary vessels and nerves. Nerve-supply.—Internal anterior thoracic from the inner cord of the brachial plexus. Costo-coracoid Membrane.—In order to see the next muscle it is necessary to remove a strong sheet of fascia which covers it in ; this is called the costo-coracoid membrane. It is a process of deep cervical fascia which, passing beneath the clavicle, encloses the sub- PECTORALIS MAJOR. SERRATUS MAGNUS. clavius, and is stretched across from the cartilage of the first rib to the coracoid process. It becomes thinner as it passes downwards, and may be traced to the upper edge of the pectoralis minor ; it encloses that muscle, and from its lower border is continued down- wards to join the axillary fascia and the fascia covering the short head of the biceps. Between the subclavius and pectoralis minor it covers in the first part of the axillary artery, and is pierced by the cephalic vein, acromial thoracic artery and vein, superior thoracic artery and anterior thoracic nerves. The SUBCLAVIUS arises by a round tendon from the cartilage and adjacent osseous part of the first rib ; it is inserted into the under surface of the clavicle near the coraco-clavicular ligament. It lies in a groove on the inferior aspect of the clavicle. Relations.—By its upper surface with the clavicle. By the loicer with the subclavian artery and vein and brachial plexus, which separate it from the first rib. In front with the pectoralis major, the costo-coracoid membrane being interposed. Nerve-supply.—A branch from the fifth and sixth cervical. Actions.—The pectoralis major draws the arm across the thorax, while its upper fibres assist the upper part of the trapezius in raising the shoulder, as in supporting weights. The lower fibres depress the shoulder with the aid of the latissimus dorsi. Taking its fixed point from the shoulder, the pectoralis major assists the pectoralis minor, subclavius, and serratns magnus in drawing up and expand- ing the chest. The pectoralis minor, in addition to this action, draws the coracoid process downwards and forwards, and rotates the scapula on the chest wall in such a manner as to direct the glenoid cavity downwards. The subclavius draws the clavicle downwards and forwards, and thereby assists in steadying the shoulder. All the muscles of this group are agents in forced inspiration, but are in- capable of acting in that capacity until the shoulders are fixed. Lateral Thoracic Region. Serratns Magnus. The SERRATUS MAGNUS (serratns, indented like the edge of a saw), broad, thin, and trapezoid in shape, arises by nine fleshy serra- tions from the eight upper ribs (two of the serrations being attached to the second rib), and extends backwards upon the side of the chest, to be inserted into the whole length of the base of the scapula, its anterior aspect. In structure, the muscle is composed of three por- tions : superior, formed by the first and second serrations and inserted into the inner surface of the superior angle of the scapula ; middle, composed of the third and fourth serrations and inserted into the greater part of the posterior border ; inferior, consisting of the last five serrations : these latter interdigitate with the obliquus externus and form a thick muscular fasciculus, which is inserted into the scapula near its inferior angle. 320 SUBSCAPULARIS. Relations.—By its superficial surface with the pectoral is major and minor, subscapularis, latissimus dorsi, and axillary vessels and nerves. By its deep surface with the ribs and intercostal muscles, to which it is connected by loose areolar tissue. Nerve-supply.—Posterior thoracic nerve, from the fifth and sixth cervical. Actions.—The serratus raagnus is the great muscle of forced inspiration, raising the ribs when the shoulders are fixed, and thereby increasing the cavity of the chest. By drawing the scapula for- wards it allows of the further outstretching of the arm after it has been raised, as in the action called extension in fencing. Along with the trapezius it rotates the scapula so as to project its inferior angle, and thus assists in raising the arm above the level of the shoulder. It is also of service in all movements of pushing. Anterior Scapular Region. The SUBSCAPULARIS arises from tlie whole of the ventral surface of the scapula excepting the superior and inferior angle and pos- terior border, and terminates by a broad and thick tendon, which is inserted into the lesser tuberosity of the humerus, and by muscular fibres into the surface of bone immediately below that process. In structure the subscapularis is composed of eight or ten fasciculi, four or five of which arise from one side of as many aponeurotic processes attached to the ridges of the venter of the scapula ; and four or five proceed from the other side of the aponeurotic processes and from the surface of bone intervening between them. Its tendon forms part of the capsule of the slioulder-joint, glides over a large bursa which separates it from the base of the coracoid process, and is lined by a prolongation of the synovial membrane of the articulation. Relations.—By its anterior surface with the serratus magnus, coraco-brachialis, and axillary vessels and nerves. By its posterior surface with the scapula and shoulder-joint. Nerve-supply.—The short and middle subscapular nerves, branches from the posterior cord of the brachial plexus. Action.—It rotates the head of the humerus inwards, and is a powerful defence to the joint. When the arm is raised, it draws the humerus downwards. Subscapularis. Posterior Scapular Region. Supra-spinatus, Teres minor, Infra-spinatus, Teres major. The SUPRA-SPINATUS muscle (supra, above ; spina, tlie spine) arises from the supra-s]>inous fossa, spine of the scapula, and proper investing fascia ; and is inserted into the uppermost depression on INFRA SPINATUS AND TERES MUSCLES. 321 the greater tuberosity of the humerus, the tendon being united near its attachment with that of the infra-spinatus. The tendon cannot be seen until the acromion process is removed. Relations.—By its upper surface with the trapezius, clavicle, acromion, and coraco-acromial ligament. From the trapezius it is separated by a strong fascia. By its lotoer surface with the supra- spinous fossa, supra-scapular vessels and nerve, origin of the omo- hyoid muscle, and upper part of the shoulder-joint. Nerve-supply.—The supra-scapular nerve, a branch from the fifth and sixth cervical. The INFRA-SPINATUS {infra, beneath ; spina, the spine) is covered in by a layer of tendinous fascia, which must be removed before the fibres of the muscle can be seen, the deltoid muscle having been previously turned down from its scapular origin. It arises from the whole of the infra-spinous fossa, excepting the in- ferior angle, axillary border, and a small portion near the neck of the bone : from the spine of the scapula, and from the investing fascia ; it is inserted into the middle depression of the greater tuberosity of the humerus, its tendon being blended with that of the supra-spinatus above and the teres minor below. Relations.—By its posterior surface with the deltoid, latissimus dorsi, trapezius, and integument. By its anterior surface with the infra-spinous fossa, supra-scapular and dorsal scapular vessels, and shoulder-joint. By its upper border it is in relation with the spine of the scapula, and by the hirer with the teres major and minor, being closely united with the latter. Nerve-supply.—The supra-scapular nerve. The TERES MINOR {teres, round) arises from the posterior surface of the axillary border of the scapula for about the middle third of its extent ; it is connected with the lower border of the preceding muscle, and is inserted into the inferior depression of the greater tuberosity of the humerus. The tendons of the three preceding muscles are in immediate contact with the shoulder-joint. Relations.—By its posterior surface with the deltoid and integu- ment. By its anterior surface with the inferior border and part of the dorsum of the scapula, dorsalis scapulae vessels, scapular head of the triceps, and shoulder-joint. By its upper border with, the infra-spina- tus ; by the lower with the teres major, and long head of the triceps. Nerve-supply.—A branch of the circumflex nerve. This branch is distinguished by a ganglionic enlargement, just before it enters the muscle. The TERES MAJOR muscle arises from the dorsal surface of the inferior angle of the scapula, and from its axillary border ; it is inserted into the internal bicipital ridge of the humerus, immediately behind the tendon of the latissimus dorsi. At its origin this muscle is covered by the latissimus dorsi, but the latter shortly afterwards curves around its lower border and becomes placed in front; the two tendons at their insertion, one lying behind the other, are separated by a bursa. 322 TRIANGULAR AND QUADRANGULAR SPACES. Relations.—By its posterior surface with the latissimus dorsi, scapular head of the triceps, and integument. By its anterior surface with the subscapularis, latissimus dorsi, coraco-brachialis, short head of the biceps, axillary vessels, and nerves of the brachial plexus. By its upper border it is in relation with the teres minor, from which it is separated by the scapular head of the triceps ; and, by the lower, forms, with the latissimus dorsi, the lower and posterior border of the axilla. Nerve-supply.—Middle and long subscapular branches derived from the posterior cord of the brachial plexus. Triangular and Quadrangular Spaces.—A large triangular space exists between the two teres muscles, which is divided into two minor spaces by the long head of the triceps. The smaller of the two spaces is placed posteriorly ; it is triangular in form, being bounded above by the teres minor, below by the teres major, and Fir:. 223.—Scapular muscles, vessels, and nerves. 1. Supra-scapular nerve. 2. Cir- cumflex nerve. 3. Supra-spinatus. 4. Posterior circumflex artery. 5. Infra- spinatus. 6. Deltoid (reflected). 7. Teres major and latissimus. 8. Brachial artery. 9. Teres minor. 10. Muscular spiral nerve. 11. Dorsalis scapula; artery. 12. Triceps (outer head). 13. Triceps (long head). in front by the long head of the triceps. It gives passage to the dorsalis scapulae vessels. The anterior space is quadrangular, and is bounded above by the teres minor, below by the teres major, in front by the humerus, and behind by the long head of the triceps ; it transmits the posterior circumflex vessels and circumflex nerve. Actions.—The supra-spinatus raises the arm from the side ; but feebly, from the disadvantageous direction of its force. The infra- DELTOID. spinatus and teres minor are rotators of the head of the humerus outwards. The most important use of these three muscles is the protection of the joint, and defence against displacement of the head of the humerus, in which action they co-operate with the sub- scapularis. The teres major combines with the latissimus dorsi in rotating the arm inwards, and at the same time carrying it towards the side, and somewhat backwards. Acromial Region. Deltoid. The DELTOID (A, delta ; efSoy, like) is the large triangular muscle which forms the convexity of the shoulder; it arises from the outer third of the clavicle, from the acromion process, and from the whole length of the lower border of the spine of the scapula. The fibres from this broad origin converge to the middle of the outer side of the humerus, where they are inserted into a rough triangular elevation. In structure the deltoid is composed of seven fasciculi, four of which are fleshy above and tendinous below ; and three tendinous above and fleshy below. To bring the muscles beneath it into view, the deltoid must be cut away from its origin, and turned down ; in so doing, a large bursa will be seen between its under surface and the head of the humerus. Relations.—By its superficial surface with the deep fascia, a few fibres of the platysma myoides, the superficial fascia, and integu- ment. By its deep surface with the shoulder-joint (from which it is separated by a thin tendinous fascia and a synovial bursa), the coraco-acromial ligament, coracoid process, pectoralis minor, coraco- brachialis, both heads of the biceps, tendon of the pectoralis major, tendon of the supra-spinatus, infra-spinatus, teres minor, teres major, scapular and external heads of the triceps, anterior and posterior circumflex vessels, and humerus. By its anterior border with the external border of the pectoralis major, from which it is separated by an interspace, lodging the cephalic vein and descending branch of the thoracico-acromialis artery. Its posterior border is thin and tendinous above, where it is connected with the aponeurotic cover- ing of the infra-spinatus muscle, and thick below. Nerve-supply.—The circumflex nerve, from the posterior cord of the brachial plexus. Actions.—The deltoid is the elevator muscle of the arm in a direct line, and, by means of its extensive origin, it can carry the arm forwards or backwards so as to range with the hand a con- siderable segment of a large circle. The arm, raised by the deltoid, is an illustration of a lever of the third power, so common in the animal machine, by which velocity is gained at the expense of power. In this lever, the weight (hand) is at one extremity, the fulcrum (glenoid cavity) at the opposite end, the power (insertion of the muscle) between the two, but nearer to the fulcrum than to the weight. When the scapula is fixed the deltoid can only raise 324 ANTERIOR HUMERAL REGION. the arm to a level with the shoulder, all elevation above that level depending upon its rotation, the glenoid cavity being in this way directed upwards and outwards (see page 200). Anterior Humeral Region. Coraco-bracliialis, Biceps brachii, Bracliialis anticus. Dissection.—These muscles are exposed on the removal of the integumentand fascia from the anterior half of the upper arm, and the clearing away of the areolar tissue. The CORAC0- BRACHIALIS, a name suggestive of its points of origin and insertion, arises from the apex of the cora- coid process in com- mon with the short head of the biceps ; and is inserted into a smooth impression on the inner side of the middle of the humerus. Relations. — By its anterior surface with the deltoid and pectoralis major. By its posterior surface with the shoulder- joint, humerus, sub- scapularis, teres major, latissimus dorsi, short head of the triceps, and an- terior circumflex vessels. By its in- ternal border with the axillary and brachial vessels and nerves, particularly with the median and musculo - cutaneous nerve, by the latter of which it is pierced. By the external border with the short head of the biceps and brachial is anticus. Fig. 224.—Muscles of the front of the upper arm. 1. Coraco- clavi- cular ligament. 2. Clavicle. 3. Acromio - clavi- cular ligament. 4. Coracoid pro- cess. 5. Coraco- acromial liga- ment. 6. Pec- toralis minor. 7. Head of hu- merus enclosed in capsule of shoulder - joint. 8. Coraco - bra- cliialis. 9. Long head of triceps. 10. Subscapu- laris. 11. Pec- toralis major (cut). 12. Short head of biceps. 13. Deltoid (cut). 14. Latissimus dorsi and teres major com- bined. 15. Ten- don of biceps. 16. Long head of triceps. 17. Supinator lon- gus. 18. Inner head of triceps. 20. Brachialis anticus. 22. Bi- cipital fascia. 24. Pronatus radii teres. BICEPS AND BRACHIALIS ANTICUS. 325 Nerve-supply.—The external cutaneous nerve which pierces it about its middle. The BICEPS BRACHII (bis—caput, two heads ; flexor cubiti) arises by two tendons ; one, the short head, from the coracoid process in common with the coraco-brachialis ; the other, the long head, from the upper part of the glenoid cavity, where it is continuous with the glenoid ligament. The muscle is inserted by a flattened tendon into the back part of the tubercle of the radius. The long head, a long slender tendon, passes through the capsular ligament of the shoulder-joint enclosed in a sheath of the synovial membrane ; after leaving the cavity of the joint, it is lodged in the deep groove that separates the two tuberosities of the humerus, the bicipital groove. A small synovial bursa is interposed between the tendon of insertion and the tubercle of the radius. At the bend of the elbow, the tendon of the biceps gives off from its inner side a tendinous band, which spreads out to form a sheet of fascia called the semilunar or bicipital fascia; it protects the brachial artery, and is continuous with the fascia of the forearm. The biceps occasionally has a third head, connected with the humerus ; this most frequently arises from the shaft of that bone in connection with the insertion of the coraco-brachialis and origin of the brachialis anticus, and is inserted into the back part of the bicipital fascia and inferior tendon of the muscle. Relations.—By its anterior surface with the deltoid, pectoralis major, superficial and deep fascia, and integument. By its posterior surface the short head rests on the subscapularis, from which it is separated by a bursa. In the rest of its extent the muscle is in relation with the humerus, teres major, latissimus dorsi, and bra- chialis anticus ; from the latter it is separated by the musculo- cutaneous nerve. By its inner border with the coraco-brachialis, brachial artery and veins, and median nerve ; the brachial vessels crossing its tendon at the bend of the elbow. By its outer border with the deltoid and supinator longus. Nerve-supply.—The external or muscular cutaneous nerve. The BRACHIALIS ANTICUS is a broad muscle covering the whole of the anterior surface of the lower part of the humerus ; it arises by two fleshy serrations, which embrace the insertion of the deltoid, from the anterior surface of the humerus, and from the inner inter- muscular septum. Its fibres converge to be inserted into the base of the coronoid process of the ulna, between two processes of the flexor profundus digitorum. Relations.—By its anterior surface with the biceps, musculo- cutaneous nerve, brachial artery and veins, and median nerve. By its posterior surface with the humerus, anterior ligament of the elbow-joint, and intermuscular septum. The latter separates it from the triceps. By its external border with the supinator longus, extensor carpi radialis longior, musculo-spiral nerve, and recurrent radial artery. By its internal border with the intermuscular septum (which separates it from the triceps and ulnar nerve), and with the pronator radii teres. 326 POSTERIOR HUMERAL REGION. Nerve-supply. — The musculocutaneous and musculo-spiral nerves. Actions.—The coraco-bracliialis draws the humerus inwards, and assists in flexing it upon the scapula. The biceps is one of the chief flexors of the elbow-joint; it is also an important supinator, this action resulting from the attachment of the tendon to the back part of the tubercle of the radius. It makes tense the fascia of the forearm, and so assists the muscles connected with the fascia. Its long tendon passing through the shoulder- joint acts as a ligament, keeping the head of the humerus in its place, and the same tendon, where it lies in the bicipital groove, limits the outward rotation of the humerus in supination, by pressing against the lesser tube- rosity. Lastly, the biceps acts as an extensor of the arm at the shoulder, assisting the deltoid. The brachialis anticus is a powerful flexor of the elbow, and in some measure supplies the place of an anterior ligament to that joint. Posterior Humeral Region. Triceps brachii. Dissection. — Remove the integu- ment and fascia from the posterior aspect of the upper arm. The TRICEPS BRACHII (having three heads ; triceps extensor cubiti) arises by three heads : external, middle, and internal. The external head arises from the outer part of the posterior surface of the humerus in a line extending from the insertion of the teres minor to the musculo-spiral groove, and from a ten- dinous arch derived from the upper part of the external intermuscular septum and bridging over the upper part of the groove. The internal head is attached to the inner margin of the humerus below the insertion of the teres major, to the whole of the posterior surface of the bone below the musculo- spiral groove to the back of the internal condyle and posterior aspect of both external and internal intermuscular septum, 't he middle or long head arises by a tendon from the ridge below the glenoid cavity of the scapula and the adjoining rough portion Fig. 225.—Posterior view of the upper arm, and triceps muscle. 1. External head. 2. Long or scapular head. 3. Internal or short head. 4. Olecranon pro- cess of ulna. 5. Radius. 6. Cap- sular ligament of the shoulder- joint. PRONATOR RADII TERES. of that bone. The three heads, passing downwards in different directions, unite to form a broad muscle, which is inserted into the olecranon process of the ulna, and sends an expansion to the deep fascia of the forearm. A small bursa is situated between the tendon of the muscle and the upper part of the olecranon. Beneath the lower part of the triceps are two small fasciculi arising from the humerus, and descending one on either side of the fossa of the olecranon to be inserted into the capsule of the elbow-joint. These have been named sub-anconeus ; they are analogous to the sub-crureus. Relations.—By its 'posterior surface with the deep and superficial fascia and integument. By its anterior surface with the superior profunda artery, musculo-spiral nerve, humerus, intermuscular septa which separate it from the brachialis anticus, and elbow-joint. The scapular head is in relation posteriorly with the deltoid and teres minor ; anteriorly with the subscapularis, teres major, and latissi- mus dorsi; and externally with the interior circumflex vessels and nerve. Nerve-supply.—The musculo-spiral nerve. Actions.—The triceps brachii is an extensor of the forearm. When the arm has been raised at the shoulder, the long head assists the teres major and latissimus dorsi, in drawing it down again to the side of the chest. Anterior Brachial Region. Superficial Layer. Pronator radii teres, Flexor carpi radialis, Palmaris longus, Flexor sublimis digitorum, Flexor carpi ulnaris. Dissection.—These muscles are brought into view by making an incision through the integument along the middle line of the fore- arm, crossing each extremity by a transverse incision, and turning aside the Haps. The superficial and deep fascia are then to be removed. The PRONATOR RADII TERES arises by two heads : one from the anterior aspect of the inner condyle of the humerus, fascia of the forearm, and intermuscular septum ; the other from the inner side of the coronoid process of the ulna ; the median nerve passing between them. Its tendon is flat, and is inserted into the middle of the outer side of the shaft of the radius. The two heads of this muscle are best examined by cutting through that which rises from the inner condyle, and turning it aside. The second head will then he seen with the median nerve lying across it. Relations.—By its anterior surface with the deep fascia of the forearm, supinator longus, extensor carpi radialis longior and brevior, 328 radial artery and veins, and radial nerve. By its 'posterior surface with the bracliialis anticus, flexor sublimis digitorum, ulnar artery and veins, and the median nerve after it has passed between the two heads of the muscle. By its upper border it forms the inner boundary of the triangular space, in which the termination of the brachial artery is situated. By its lower border it is in relation with the flexor carpi radialis. Nerve-supply.—Median nerve. The FLEXOR CARPI RADIALIS arises from the inner condyle, deep fascia, and intermuscular septa. Its tendon perforates the anterior annular ligament, and passes through a groove in the trapezium bone, to be inserted into the base of the metacarpal bones of the index and middle fingers. The groove is converted into a canal by a fibrous band, and is lined bv a synovial membrane. Relations.—By its an- terior surface with the deep fascia of the forearm, and at the wrist with the ten- dinous canal through which its tendon passes. By its posterior surface with the flexor sublimis digitorum, flexor longus pollicis, wrist- joint, and groove in the trapezium bone. By its outer border with the pronator radii teres, radial artery and veins. By its inner border with the palmaris longus. Nerve-supply.—Median nerve. The PALMARIS LONGUS is a small muscle which arises from the inner condyle, deep fascia, and intermuscular septa. Its tendon pierces the deep fascia and crosses the annular ligament to be inserted into the palmar fascia. This muscle is often absent. Relations.—By its anterior surface with the dee]) fascia of the forearm. By the posterior surface with the flexor sublimis digito- rum ; to the external side with the flexor carpi radialis ; and to the internal side with the flexor carpi ulnaris. Nerve-supply.—Median nerve. FLEXOR MUSCLES OF FOREARM. Fio. 226. — Super- ficial layer of muscles of the forearm. 1. Bi- ceps, with its ten- don. 2. Brachialis anticus, seen be- neath biceps. 3. Part of triceps. 4. Pronator radii teres. 5. Plexor carpi radialis. 6. Palmaris longus. 7. One of the fasci- culi of the flexor sublimis digito- rum ; the rest of the muscle is seen beneath the ten- dons of the pal- maris longus and flexor carpi radia- lis. 8. Flexor carpi uhiaris. 9. Pal- mar fascia. 10. Palmaris brevis. 11. Abductor pol- licis. 12. Flexor brevis pollicis; the leading line crosses part of the adductor pollicis. 13. Supinator lon- gus. 14. Extensor ossis metacarpi and ex tensor primi internodii pollicis, curving around the lower border of the forearm. FLEXOR SUBLIMTS DIGITORUM. 329 Dissection.—Cut the flexor carpi radialis and palmaris longus from their origin, in order to obtain a good view of the whole extent of origin of the flexor sublimis digitorum. The FLEXOR SUBLIMIS DIGITORUM (perforatus) arises from the inner condyle, intermuscular septa, internal lateral ligament, coro- noid process of the ulna, and oblique line of the radius. The median nerve and ulnar artery pass between its heads. It divides into four tendons, which pass beneath the annular ligament, and are inserted into the sides of the second phalanges of the fingers about their middle, splitting at their termination to give passage to the tendons of the deep flexor ; hence its designation, perforatus. The tendons pass beneath the annular ligament arranged in pairs, those for the middle and ring fingers being placed superficially, and those for the index and little fingers beneath them. At the bases of the first pha- langes the flexor tendons enter small canals which are in part formed by the grooved surfaces of the bones, and in part by fibrous arches thrown across the tendons ; these are called thecae (Orjica, a case). In Fig. 227.—Bones of two fingers with the insertion of the tendons. In A the tendons of the flexor muscles are bound to the bone by the fibrous sheath. In B the sheath has been removed, as well as the vincula accessoria. 1. Metacarpal bone. 2. Ten- don of the flexor sublimis. 3. Tendon of the flexor profundus. * Perforation of the sublimis by the profundus tendon. 4. Tendon of the extensor communis digi- torum. 5. Lumbricalis muscle. 6. One of the interossei muscles. the thecse of the fingers several small tendinous fasciculi are found, which pass from the phalanges to the edges of the tendons ; these have been termed the vincula accessoria. One of these connects the deep tendon with the bone before it pierces the superficial tendon ; another connects the superficial and deep tendon after the latter has passed through the former ; and a third connects the deep tendon with the head of the second phalanx. This last consists largely of elastic tissue, and may assist in reinstating the tendon after flexion of the finger. Relations.—In the forearm : by its anterior surface with the pronator radii teres, flexor carpi radialis, palmaris longus, flexor caipi ulnaris, and the deep fascia. By its posterior surface with the flexor profundus digitoruin, flexor longus pollicis, ulnar artery, veins, DEEP MUSCLES OF FOREARM. and nerve, and median nerve. Tliis muscle frequently sends a fasci- culus to tlie flexor longus pollicis or flexor profundus. In the hand : its tendons, after passing beneath the annular ligament, are in relation superficially with the superficial palmar arch, and palmar fascia; and deeply with the tendons of the deep flexor anil lumbricales. Nerve-supply.—Median nerve. The FLEXOR CARPI ULNARIS arises by two heads, one from the inner condyle and intermuscular septa, the other from the ole- cranon and by means of a strong aponeurosis from two-thirds of the posterior border of the ulna. Its tendon is inserted into tin* pisiform bone, anterior annular ligament, and base of the metacarpal bone of the little linger. Relations.—By its anterior surface with the deep fascia of the forearm, with which it is closely united superiorly. By its pos- terior surface with the flexor sublimis cligi- torum, flexor profundus, pronator quadratus, ulnar artery, veins, and nerve. By its radial border with the palmaris longus, and in the lower third of the forearm, the ulnar vessels and nerve. The ulnar nerve, and the pos- terior ulnar recurrent artery, pass between its two heads of origin. Nerve-supply.—Ulnar nerve. Deep Layer. Flexor profundus digitorum, Flexor longus pollicis, Pronator quadratus. Dissection.—This group is brought into view by removing the flexor sublimis, and drawing aside the pronator radii teres. The FLEXOR PROFUNDUS DIGITORUM (perforans) arises from the upper two-thirds of the ulna, its anterior and inner surface and posterior border, from the inner side of the olecranon, where it is connected with the aponeurotic expansion of the flexor carpi ulnaris, and from the xilnar half of the interosseous membrane. At the middle of the forearm it divides into four tendons which pass beneath the Fio. 228.—Deep layer of muscles of the forearm, x. Internal lateral liga- ment of the elbow-joint. 2. Anterior ligament. 3. Orbicular ligament of the head of the radius. 4. Flexor profundus digitorum. 5. Flexor longus pollicis. 6. Pro- nator quadratus. 7. Ad- ductor pollicis. 8. Dorsal interosseous of the mid- dle, and palmar interos- seous of the ring finger. 9. Dorsal interosseous muscle of the ring finger, and palmar interosseous of the little finger. FLEXOR LONGUS POLLICIS. annular ligament, and along the fingers, between the two slips of the tendons of the flexor sublimis, to be inserted into the base of the last phalanges. In the groove of the carpus the tendons are enclosed in a synovial membrane, and the three outer tendons communicate with each other by means of small slips, the tendon of the index- finger remaining distinct. In the hand, the tendons give origin to the lumbricales muscles, and on the second phalanges are retained in position by two little tendinous slips, the vincula accessoria. Relations.—In the forearm : by its anterior surface with the flexor sublimis digitorum, flexor carpi ulnaris, median nerve, and ulnar artery, veins, and nerve. By its posterior surface with the ulna, interosseous membrane, pronator quadratus, and wrist-joint. By its radial border with the flexor longus pollicis, the anterior interosseous artery and nerve being interposed. By its ulnar border with the flexor carpi ulnaris. In the hand : its tendons are in relation superficially with the tendons of the superficial flexor; and deeply with the interossei, adductor pollicis, and deep palmar arch. Nerve-supply.—Median and ulnar nerves. The FLEXOR LONGUS POLLICIS arises from the anterior surface of the shaft of the radius for two-thirds of its extent, and from Fig. 229.—Varieties in the arrangement of the synovial sheaths of the wrist and fingers. The middle one is the most frequent. one-lialf the interosseous membrane. Its tendon passes beneath the annular ligament to be inserted into the base of the last phalanx of the thumb. Relations.—By its anterior surface with the flexor sublimis digi- torum, flexor carpi radialis, supinator longus, and radial artery and veins. By its •posterior surface with the radius, interosseous mem- brane, pronator quadratus, and wrist-joint. By its ulnar border, it is separated from the flexor profundus digitorum by the anterior interosseous artery and nerve. In the hand : after passing beneath the annular ligament, it is lodged in the interspace between the two portions of the flexor brevis pollicis, and afterwards in the tendinous theca of the phalanx. Synovial Sheaths.—Beneath the anterior annular ligament two synovial sheaths are found ; the larger of these surrounds the tendons of flexor sublimis and flexor profundus digitorum, and 332 ACTIONS OF FLEXOR MUSCLES OF FOREARM. extends from a little above the annular ligament to about the middle of the palm. The smaller sheath surrounds the flexor longus pollicis, and extends from above the annular ligament to the base of the second phalanx of the thumb. Between the two sheaths the median nerve lies, or it may occupy the larger sheath along with the flexor tendons. Each of the fingers has a digital synovial sheath commencing above the metacarpo-phalangeal joint and terminating at the base of the last phalanx ; the digital sheath of the little linger generally communicates with the common sheath beneath the annular ligament. The commonest variations in the synovial sheaths are shown in Fig. 229. Nerve-supply.—Anterior interosseous, a branch of the median. Dissection.—If the tendons of the last two muscles lie drawn aside or divided, the third muscle of this group will be brought into view, lying across the lower part of the two bones. The PRONATOR QUADRATUS arise.s from the anterior and inner side of the ulna, and is inserted into the front of the radius. This muscle occupies about the lower fourth of the two bones, is broad at its origin, and narrower at its insertion. Relations.—By its anterior surface with the tendons of the supi- nator longus, flexor carpi radialis, Hexor longus pollicis, flexor pro- fundus digitorum, and flexor carpi ulnaris, radial artery and veins, and ulnar artery, veins, and nerve. By its posterior surface with the radius, ulna, and interosseous membrane. Nerve-supply.—Anterior interosseous, a branch of the median. Actions.—The pronator radii teres and pronator quadratus rotate the radius upon the ulna, and render the hand prone. The remain- ing muscles are flexors : two flexors of the wrist, flexor carpi radialis and ulnaris ; two of the fingers, flexor sublimis and profundus, the former flexing the second phalanges, the latter the last; one flexor of the last phalanx of the thumb, flexor longus pollicis. The palmaris longus is primarily a tensor of the palmar fascia, and secondly a flexor of the wrist and forearm. The muscles which arise from the internal condyle of the humerus act as flexors of the elbow-joint, those which pass to the radial side of the hand and arm being more effective in this respect than the muscles on the ulnar side. The flexor carpi ulnaris is an effective pronator in the early part of its action, and when the hand is placed in the position of supination. The superficial and deep flexors of the fingers assist in producing flexion of the wrist, after the tlexion of the fingers is completed, or when the fingers are fixed by being pressed against an opposing surface. Posterior Brachial Region. Supinator longus, Extensor minimi digiti, Extensor carpi radialis longior, Extensor carpi ulnaris, Extensor carpi radialis brevior, Anconeus. Extensor communis digitorum, Superficial Layer. SUPINATOR longus. Dissection.—Tlie integument is to be divided and turned aside, and the fascia removed in the same manner as for the anterior brachial region. The SUPINATOR LONGUS is placed along the radial border of the forearm. It arises from the upper two-thirds of the external supra- condylar ridge of the humerus, reaching as high as the musculo- spiral groove, and from the external intermus- cular septum, passes for- ward to the anterior as- pect of the elbow-joint, and ends in a long Hat tendon, which descends the forearm to be inserted into the outer side of the base of the styloid process of the radius. Relations. — By its superficial surface with the extensor ossis meta- carpi pollicis, extensor primi internodii pollicis, and deep fascia of the fore- arm. By its deep surface with the brachialis anti- cus, extensor carpi radialis longior, tendon of the biceps, supinator brevis, pronator radii teres, flexor- carpi radialis, flexor sub- limis digitoruin, flexor longus pollicis, pronator quadratus, radius, mus- culo-spiral nerve, radial and posterior interosseous nerve, and radial artery and veins. N erve-supply.—A special branch of the nrusculo-spiral. Dissection.—This muscle must be divided through the middle, and the two ends turned aside to expose the next muscle. The EXTENSOR CARPI RADIALIS LONGIOR arises from the lower third of the external supracondylar ridge, immediately below the preceding, and from the intermuscular septum. Its tendon passes through a groove in the radius behind the styloid process, to be inserted into the base of the metacarpal bone of the index-finger. Relations.—By its superficial surface with the supinator longus, extensor ossis metacarpi pollicis, extensor primi internodii pollicis, 333 al bone of the thumb on its radial border. Nerve - supply. Median nerve. Relations.—By its superficial surface witl the abductor pollicis By its deep surface witl the trapezo - metacar pal articulation anc metacarpal bone. In ternally with the flexo brevis pollicis. The flexor ossis metacarpi may now be divided fron its origin and turned aside, in order to show the next muscle. The FLEXOR BREVIS POLLICIS consists of two portions, betweei which lies the tendon of the flexor longus pollicis. The externa portion arises from the trapezium and annular ligament; the in ternal portion from the trapezoid, os magnum, and base of the second and third metacarpal hones. They are inserted into the two sides of the base of the first phalanx of the"thumb, having a sesamok Fin. 232.—Insertion of the muscles of the thumb, a. Abductor pollicis. b. Opponens pollicis. c. Outer head of flexor brevis, d. Tendon of extensor secundi internodii. e. Tendinous expansion of flexor brevis, joining tendon of extensor. ADDUCTOR POLLTCIP. 339 bone in each of their tendons to protect the joint, and send tendinous slips to join the tendon of the extensor secundi internodii at the back of the first phalanx. The outer head is joined by a considerable bundle of fibres from the inner, which passes obliquely behind the long flexor tendon in order to reach it. Relations.—By its superficial surface with the external portion of the palmar fascia. By its deep surface with the adductor pollicis, tendon of the flexor carpi radialis, and trapezo-metacarpal articula- tion. By its external surface with the flexor ossis metacarpi and metacarpal bone. By its inner surface with the tendons of the long flexor muscles and first lumbricalis. Nerve-supply.—Outer head by the median nerve, inner by the ulnar. The ADDUCTOR POLLICIS is a triangular muscle ; it arises by a broad origin from the middle two-thirds of the palmar surface of the metacarpal bone of the middle finger ; the fibres converge to its insertion into the base of the first phalanx of the thumb and internal sesamoid hone, where it is united with the inner head of the flexor brevis. Relations.—By its anterior surface with the flexor brevis pollicis, tendons of the deep flexor of the fingers, lumbricales, and deep palmar arch. By its posterior surface with the metacarpal bones of the index and middle finger, the interossei of the second inter- osseous space, and the first dorsal interosseous. Its inferior border is subcutaneous. Nerve-supply.—Ulnar nerve. Ulnar or Hypothenar Region. Palmaris brevis, Abductor minimi digiti, Flexor brevis minimi digiti, Flexor ossis metacarpi. Dissection.—Turn aside the ulnar dap of integument from the palm of the hand ; in doing this, a small subcutaneous muscle, the palmaris brevis, will be exposed. After examining this muscle, remove it with the deep fascia, in order to bring into view the muscles of the little finger. The PALMARIS BREVIS is a thin plane of muscular fibres about an inch in width, which arises from the annular ligament and palmar fascia, and passes transversely inwards to be inserted into the integu- ment of the inner border of the hand. Relations.— By its superficial surface with the fat and integument of the inner portion of the palm. By its deep surface with the ulnar portion of the palmar fascia, which separates it from the ulnar artery, veins, and nerve, and from the muscles of the inner border of the hand. Nerve-supply.—Ulnar nerve. The ABDUCTOR MINIMI DIGITI is a small tapering muscle which arises from the pisiform bone, where it is continuous with the tendon MUSCLES OF THE PALM. 340 of the flexor carpi ulnaris, and is inserted into the base of the first phalanx of the little, finger, and into the expansion of the extensor tendon. Relations.—By its superficial surface with the internal portion of the deep fascia and palmaris brevis ; by its deep surface with the flexor ossis metacarpi and metacarpal bone. By its inner border with the flexor brevis minimi digiti. Nerve-supply.—Ulnar nerve. The FLEXOR BREVIS MINIMI DIGITI is a small muscle arisiny from the unciform bone and annular ligament, and inserted into the base of the first phalanx of the little finger in connection with the preceding muscle. It is sometimes wanting. Relations.—By its superficial surface with the internal portion of Fig. 233.—Muscles of the hand. 1. Annular ligament. 2, 2. Origin and insertion of the abductor pollicis muscle; the middle por- tion has been removed. 3. Flexor ossis metacarpi, or opponens polli- cis. 4. Superficial portion of the flexor brevis pollicis. 5. Deep portion of the flexor brevis pollicis. 6. Adductor pollicis. 7, 7. The lumbricales muscles, arising from the deep flexor tendons, upon which the figures are placed. The tendons of the flexor sublimis have been removed. 8. One of the ten- dons of the deep flexor, passing between the two terminal slips of the tendon of the flexor sublimis to reach the last phalanx. 9. The tendon of the flexor longus polli- cis, passing between the two por- tions of the flexor brevis to the last phalanx. 10. Abductor minimi digiti. 11. Flexor brevis or op- ponens minimi digiti. The edge of the flexor ossis metacarpi is seen projecting beyond the inner border of the flexor brevis. 12. Pisiform bone. 13. First dorsal interosseous muscle, the abductor indicia. the palmar fascia, and palmaris brevis. By its deep surface with the flexor ossis metacarpi and metacarpal bone. Externally with the abductor minimi digiti, from which it is separated near its origin by the deep palmar branch of the ulnar nerve and communicating artery. Internally with the tendons of the flexor sublimis and profundus. Nerve-supply.—Ulnar nerve. The FLEXOR OSSIS METACARPI or OPPONENS MINIMI DIGITI arises from the unciform bone and annular ligament, and is inserted into the whole length of the metacarpal bone of the little finger on its ulnar border. Relations.—By its superficial surface with the flexor brevis and LUMBRICALES AND INTEROSSEI. abductor minimi digiti. By its deep surface with the interossei muscles of the last metacarpal space, metacarpal bone, and flexor tendons of the little finger. . Nerve-supply.—Ulnar nerve. Palmar Region. Lumbricales, Palmar interossei, Dorsal interossei The LUMBRICALES, four in number, are accessories to the deep flexor muscle. They arise from the tendons of the deep flexor ; the first and second from the radial side of one tendon ; the third and fourth from the contiguous sides of two tendons. They j>ass to the radial side of each finger and are inserted into the aponeurotic ex- pansion of the extensor tendons on the dorsal aspect of the first phalanx. The third, or that of the tendon of the ring finger, sometimes bifurcates; at other times it is inserted wholly into the extensor tendon of the middle finger. Relations.—In the palm of the hand with the flexor tendons ; at their insertion, with the tendons of the interossei and the metacarpo- phalangeal articulations. Nerve-supply.—The two outer by the median, the two inner by the ulnar nerve. The PALMAR INTEROSSEI, three in number, are visible only on the palmar as- pect of the hand ; they are placed upon the metacarpal bones, rather than between them. They ai •ise from the base of the meta- carpal bone of one finger, and are in- serted into the base of the first phalanx and aponeurotic ex- pansion of the ex- tensor tendon of the same finger. The first belongs to the index finger ; the second, to the ring finger ; the third, to tlie little finger ; the middle finger being omitted. Relations.—By their palmar surface with the flexor tendons and deep muscles in the palm of the hand. By their dorsal surface with the dorsal interossei. On one side with the metacarpal bone, on the other with the corresponding dorsal interosseous muscle. DORSAL INTEROSSEI.—Turning to the dorsum of the hand, the four dorsal interossei are seen in the four spaces between the metacarpal bones. They are bipenniform muscles, and arise by two Fjo. 234.—Attachment of an interosseous muscle, a. In- terosseous muscle, b. Attachment to the base of first phalanx, c. Slip passing forward to d, Side of extensor tendon, e. Central portion of extensor tendon. 342 heads from adjoining sides of the bases of the metacarpal bones. They are inserted into the base of the first phalanges, and into the aponeurosis the extensor tendons. The first is inserted into the index finger, and from its use is called abductor indicis; the second and third are inserted into the middle finger, compensating its exclusion from the palmar group ; the fourth is attached to the ring linger ; so that each finger is pro- vided with two interossei, with the exception of the little finger, as may be shown by means of a table, thus :— ACTIONS OF THE MUSCLES OF THE HAND. one dorsal (abductor indicis), one palmar. Index finger, Middle finger, two dorsal. Ring finger, one dorsal, one palmar. Little finger, remaining palmar (adductor minimi digiti). Relations.—By their dorsal surface with a thin aponeurosis, which separates them from the tendons on the dorsum of the hand. By their palmar surface with the muscles and tendons in the palm of the hand. By one side with the metacarpal bone ; by the other with the corresponding palmar interosseous. The abductor indicis is in relation by its palmar surface with the adductor pollicis and llexor brevis pollicis. The radial artery passes into the palm of the hand between the two heads of the first dorsal interosseous muscle (abductor indicis); and the perforating branches of the deep palmar arch, between the heads of the other dorsal interossei. Nerve-supply.—All the interosseous muscles are supplied by the ulnar nerve. Actions.—The actions of the muscles of the hand are expressed in their names. Those of the radial region belong to the thumb, and provide for three of its movements, abduction, adduction, and flexion. The ulnar group, in like manner, are subservient to the same motions of the little finger. The lumbrieales are accessory in their actions to the deep flexors ; they were called by the earlier anatomists fidicinii—i.e., fiddlers’ muscles, from an idea that they might effect the rapid movements by which the performer is enabled to produce the various notes on that instrument. The seven in- terossei and the four lumbrieales have a double action on the fingers in consequence of being inserted partly into the bases of the first phalanges and partly into the expansion of the extensor tendon. They thus become flexors of the fingers at the metacarpo-phalangeal joint, and extensors of the two last phalanges ; the former action being due to their osseous and the latter to their tendinous insertion. The interossei are, however, chiefly concerned in flexion of the first phalanx, since the greater part of their insertion is into that bone ; the lumbrieales, again, almost entirely pass to the extensor tendon, and they thus combine the action of the flexors with that of the ex- tensors, so as to give fineness and firmness of digital action (Clark). fascia: OF THE LOWER EXTREMITY. 343 In relation to the axis of the hand, the four dorsal interossei are abductors, the three palmar adductors. It will therefore be seen that each finger is provided with its proper adductor and abductor, two flexors, and (with the exception of the middle and ring finger) two extensors. The thumb has, moreover, a flexor (opponens) and extensor of the metacarpal bone ; and the little finger a flexor of the metacarpal bone (opponens) without an extensor. The palmaris brevis draws together the skin on the ulnar margin of the hand, and so increases the hypothenar eminence and deepens the hollow of the hand. MUSCLES AND FASCLE OF THE LOWER EXTREMITY. FASCLE OF THE LOWER EXTREMITY The superficial fascia of the thigh consists of two layers, the superficial or fatty, and the deep or membranous. The first is continuous with that of the abdomen, and contains more or less fat, according to the subject. Between the two layers are contained the superficial epigastric, superficial circumflex iliac, and superficial external pudic branches of the femoral artery and vein ; also the femoral and inguinal lymphatic glands and the vessels connected with them, the crural branch of the genito-crural nerve, and the internal, middle, and external cutaneous nerves. The deep or membranous layer is thin but strong, and is attached to the fascia lata a short distance below Poupart’s ligament. It is also closely connected to the fascia lata around the margin of the saphenous opening, which it closes, and here it is more dense than elsewhere, and being pierced by openings for the superficial vessels before alluded to, it is called the cribriform fascia, which forms one of the coverings of femoral hernia. It becomes incorporated with the fascia lata as it descends, and at about six inches below the groin becomes inseparably united with it. The deep fascia of the thigh is named, from its great extent, the fascia lata ; it is thick and strong upon the outer side of the limb, and thinner on its inner and posterior aspect. That portion of the deep fascia which invests the gluteus maximus is very thin, but that which covers in the gluteus medius is excessively thick, and gives origin, by its inner surface, to the superficial fibres of that muscle. The fascia lata is attached superiorly to Poupart’s ligament, the crest of the ilium, sacrum, coccyx, tuberosity of the ischium, ramus of the ischium and pubes, body of the pubes, and pectineal line ; it has also a deep attachment (ligamentum iliacum) to the anterior border of the ilium, tendon of origin of the rectus muscle, and border of the acetabulum. It forms sheaths for the muscles bf the thigh and femoral vessels, and is connected with the linea aspera by means of two intermuscular septa, external and internal; the former extending from the insertion of the gluteus maximus to the external 344 FASCIA LATA. condyle, and separating the vastus externus from the biceps muscle ; the internal being attached to the inner branch of the linea aspera for a short distance above the internal condyle, and separating the vastus interims from the adductor magnus. The fascia lata receives the attachment of two muscles, tensor vaginae femoris and gluteus maximus, and glides over the trochanter major on a bursa. At the lower part of the thigh, the fascia forms a very distinct band of about an inch and a half in width, ilio-tibial band, which receives tendinous fibres from the extensor and flexor muscles of the thigh, and is inserted into the outer tuberosity of the tibia and head of the fibula. At the back of the knee the fascia bridges over the popliteal space, the longitudinal fibres being strengthened by numerous trans- verse fasciculi. In addition to the smaller openings in the fascia lata which transmit the small cutaneous vessels and nerves, there exists at the upper and inner ex- tremity of the thigh an oval opening, which gives passage to the superficial lymphatic vessels and the large sub- cutaneous vein of the lower extremity, the internal saphe- nous vein, and is thence named the saphenous opening. The existence of this opening has given rise to the division of the upper part of the fascia lata into two portions, an iliac portion and a pubic portion. The iliac portion is situated upon the iliac side of the open- ing. It is attached to the crest of the ilium, and along Pou- part’s ligament to the spine of the pubes, whence it is re- flected downwards and out- wards in an arched direction, and forms a falciform border (falciform process of Burns), which constitutes the outer boundary of the saphenous opening. The edge of this border immediately overlies, and is adherent to, the sheath of the femoral vessels, and the lower extremity of the curve is continuous with the pubic portion. The pubic portion, occupying the pubic side of the saphenous opening, is attached to the spine of the pubes and pectineal line ; Fig. 235.—Crural sbeatli laid open. a. Middle cutaneous nerve, c. Placed to the inner side of Gimbernat’s ligament, d. Iliac portion of fascia lata. e. Pubic portion of fascia lata. /. Margin of saphenous opening (turned hack), k. Femoral sheath opened by three incisions. 1. Saphena vein. and passing outwards behind the sheath of the femoral vessels, divides into two layers ; the anterior layer is continuous with that portion of the iliac fascia which forms the sheath of the iliacus and psoas muscle, the posterior layer is lost upon the capsule of the hip-joint. The interval between the falciform border of the iliac portion and the opposite surface of the pubic portion is closed by an areolo- tibrous layer, derived from the deep layer of the superficial fascia, and pierced by numerous openings for the passage of arteries, veins, and lymphatic vessels, the cribriform fascia. The cribriform fascia lies superficial to the sheath of the femoral vessels, and forms one of the coverings of femoral hernia. When the iliac portion of the fascia lata is removed from its attachment to Poupart’s ligament FASCIA LATA. 345 Fio. 236.—Section of the struc- tures which pass beneath the crural arch. 1. Poupart’s liga- ment. 2, 2. Iliac portion of the fascia lata, attached along the margin of the crest of the ilium, and along Poupart’s ligament, as far as the spine of the pubes (3). 4. Pubic portion of the fascia lata, continuous at 3 with the iliac portion, and passing outwards behind the sheath of the femoral vessels to its outer border at 5, where it divides into two layers; one is con- tinuous with the sheath of the psoas (6), and iliacus (7); the other (8) is lost upon the cap- sule of the hip-joint (9). 10. The anterior crural nerve. 11. Gim- bernat’s ligament. 12. The crural ring. 13. Femoral vein. 14. Femoral artery; the two vessels and the ring are sur- rounded by the femoral sheath, and thin septa are sent between the anterior and posterior wall of the sheath, dividing the artery from the vein, and the vein from the crural canal. and turned aside, the sheath of the femoral vessels (the femoral or crural canal) is brought into view ; and if Poupart’s ligament be carefully divided, the sheath may be isolated, and its continua- tion with the transversalis and iliac fascia demonstrated. In this view, the sheath of the femoral vessels is an infundibuliform con- tinuation of the abdominal fasciae, closely adherent to the vessels a little way down the thigh, but much larger than the vessels it contains at Poupart’s ligament. If the sheath be opened, the artery and vein will be found lying side by side, and occupying the outer two-tliirds of the sheath, leaving an infundibuliform interval between the vein and inner wall of the sheath ; this portion of the sheath is distinguished under a different title and called crural sheath. The superior opening of the space is named the femoral or crural ring; it is bounded in front by Poupart’s ligament, behind by FEMORAL HERNIA. 346 the os pubis, internally by Gimbernat’s ligament, and externally by the femoral vein. The interval itself serves for the passage of the superficial lymphatic vessels from the saphenous opening to a lymphatic gland, which generally occupies the femoral ring, and from thence they proceed into the current of the deep lymphatics. The crural ring is closed merely by a thin layer of sub-serous areolar tissue, which retains the lymphatic gland in its position, and is named septum crurale, and by the peritoneum. It follows from this description that the femoral ring must be a weak point in the parietes of the abdomen, particularly in the female, in whom the femoral arch, or space included between Poupart’s ligament and the border of the pelvis, is larger than in the male, while the struc- tures which pass through it are smaller. It happens, that if violent or continued pressure be made upon the abdominal viscera, a portion of intestine may be forced through the femoral ring into the infundibuliform space in the sheath of the femoral vessels, carrying before it the peritoneum and septum crurale,—this constitutes femoral hernia. If the causes which gave rise to the formation of the hernia continue, the intestine, unable to extend further down the sheath, from the close connection of the latter with the vessels, will, in the next place, be forced forwards through the saphenous opening in the fascia lata, carrying before it two additional coverings, the sheath of the vessels or fascia propria, and the cribri- form fascia; and then, curving upwards over Poupart’s ligament, the hernia will become placed beneath the superficial fascia and integument. The direction which femoral hernia takes in its descent is at first downwards, then forwards, and then upwards; and in endeavouring to reduce it, the application of the taxis must have reference to this course, and be directed in precisely the reverse order. The coverings of femoral hernia are the— Integument, Superficial fascia, Cribriform fascia, Femoral sheath, Septum crurale, Peritoneal sac. The deep fascia of the leg is attached to the inner and outer tuberosity of the tibia and head of the fibula, and receives an accession of fibres from the tendons of the sartorius, gracilis, and biceps. Be- tween its points of attachment, and especially behind, it is continuous with the fascia of the thigh. In the front of the leg it encloses the tibialis anticus and extensor muscles, and affords origin to some of their fibres. On the outer side it forms a sheath for the peronei muscles ; and behind, two sheaths, superficial and deep ; the former for the gastrocnemius and soleus with the ten do-A chillis, the latter for the deep flexor muscles. At the ankle these four sheaths arc FASCIAE OF THE LEG. 347 differently arranged ; the posterior superficial sheath terminates on the os calcis with the tendo-Achillis; the posterior deep sheath is attached at one side to the border of the internal malleolus, at the other to the os calcis and inner side of the foot, being blended with the origin of the abductor pollicis. This portion of the deep fascia is the internal annular ligament; it sends processes inwards to separate the tendons of the flexors and forms sheaths for their passage into the foot. The sheath of the peronei muscles at the outer ankle is attached to the external malleolus on one side, and the border of the os calcis on the other, and forms the external annular liga- ment. The anterior portion of the fascia forms at the ankle the anterior annular ligament; it is divisible into two parts, the upper being transversely disposed, the lower arranged in the form of the letter >- placed on its side. The latter is often described as a separate ligament under the name of cruciform ligament; it is com- posed of two bands about half-an-inch in width, blended with each other at their point of union on the front of the joint. The internal band is attached above to the internal malleolus and below to the os calcis at the outer side of the foot; the external band to the external malleolus above, and the scaphoid and internal cuneiform bone at the inner border of the foot. The internal band at its origin consists of two layers, between which passes the tendon of the tibialis anticus. The tendons of the extensor longus digitorum and peroneus tertius have also a separate loop connected with the cruci- form ligament, the sling ligament of Retzius ; this is a narrow band which embraces the tendons in a sling-shaped loop, and passes out- wards and backwards to be attached to the sulcus tali and neighbour- ing part of the calcaneum. The tendons passing through the loops and sheaths around the ankle are each furnished with a synovial bursa. That portion of the deep fascia of the leg which forms a septum between the superficial and deep muscles of the back of the leg is sometimes called the intermuscular fascia; and in operations on the arteries of that region the deep layer of the deep fascia. There is besides another deep portion of fascia above the preceding, the popliteal fascia, derived from the tendon of the semi-membranosus muscle and binding down the popliteus muscle. By its inferior border this fascia is inserted into the soleal ridge of the tibia. The fascise dorsales pedis are three in number, superficial, middle, and deep. The superficial layer of deep fascia of the foot is thin and covers the dorsum of the foot, being continuous at the ankle with the cruciform ligament, and attached at either side to the borders of the foot, where it becomes united with the plantar fascia. A second or middle layer of fascia covers in the anterior part of the extensor brevis digitorum with its tendons; and a third or deep layer is found beneath the latter, and covering in the interossei muscles. On the interossei muscles the three layers are united, and the ex- tensor tendons are consequently separated from each other in their course to the toes. 348 GLUTEAL REGION. The Plantar Fascia consists of three portions, middle and two lateral. The middle portion is thick and dense, and composed of strong aponeurotic fibres, closely interwoven with each other. It is at- tached posteriorly to the inferior surface of the tuberosities of the os calcis, and terminates under the heads of the metatarsal bones in live fasciculi. Each of these fasciculi bifurcates to embrace the base of the corresponding toe, and is attached in the middle to the sheath of the flexor tendons, and at either side to the head of the metatarsal bone. The point of division of the fascia into fasciculi is strengthened by transverse bands, which preserve the solidity of the fascia at its broadest part. The intervals between the toes give passage to the digital arteries and nerves and lumbricales muscles. The lateral ])ortions are thin, and cover the sides of the sole of the foot; they are continuous beliind with the internal and external annular ligament; and on the mesial side with the central portion. The inner portion is continuous along the border of the foot with the fascia of the dorsum ; the outer portion is attached to the os calcis and base of the metatarsal bone of the little toe, forming between these points a thick band, which gives origin to part of the abductor minimi digiti muscle. Besides constituting a strong layer of investment and defence to the soft parts situated in the sole of the foot, these three portions of fascia send processes inwards, which form sheaths for the different muscles. A strong septum (intermuscular septum) is given off from each side of the middle portion of the plantar fascia, which is attached to the tarsal bones, and divides the muscles into three groups, middle and two lateral; and transverse septa are stretched between these to separate the layers. The superficial layer of muscles derive part of their origin from the plantar fascia. Gluteal Region. Gluteus maximus, Gluteus medius, Gluteus minimus, Pyriform is. Gemellus superior, Obturator interims, Gemellus inferior, Obturator externus, Quadratus femoris. Dissection.—Tlie subject being turned on its face, and a block placed beneath the pubes to support the pelvis, the student com- mences the dissection of this region by carrying an incision from the apex of the coccyx along the crest of the ilium to its anterior superior spinous process ; or vice versa, if he be on the left side. He then reflects the integument, superficial fascia, and deep fascia, which latter is very thin over this muscle, from the gluteus maximus, follow- ing rigidly the course of its fibres ; and having exposed the muscle in its entire extent, lie dissects the integument and superficial fascia from off the deep fascia which binds down the gluteus medius, the other portion of the region. GLUTEUS MAXIMUS. 349 The GLUTEUS MAXIMUS (yXovros, nates) is the thick, fleshy mass of muscle, of a trapezoid shape, which forms the convexity of the nates. In structure it is coarse, being made up of fibres collected into large fasciculi, and these again into distinct muscular masses, separated by deep furrows. It arises from the posterior fourth of the crest of the ilium, from the rough triangular surface between the crest and superior curved line, the posterior surface of the sacrum and coccyx, and from the great sacro-ischiatic ligament. It passes obliquely outwards and downwards, to be inserted into the rough line leading from the trochanter major to the linea aspera, and is continuous by means of its tendon with the fascia lata covering the outer side of the thigh, and with the ilio-tibial band. Several bursae are situated between this muscle and subjacent parts : one upon the tuberosity of the ischium, one between its tendon and the trochanter major, and one between it and the tendon of the vastus externus. Relations.—By its superficial surface with a thin aponeurotic fascia, which separates it from the superficial fascia and integument, and near its insertion, with the vastus externus. By its deep surface with the gluteus medius, pyriformis, gemelli, obturator internus, quadratus femoris, sacro-ischiatic foramina, great sacro-ischiatic liga- ment, tuberosity of the ischium, semi-membranosus, semi-tendinosus, biceps, and adduc- tor magnus ; glu- teal vessels and nerve, ischiatic vessels and nerves, and internal pudic vessels and nerve. By its upper bor- der it overlaps the gluteus medius ; and by the lower border forms the lower margin of the nates. The gluteus maximus must be turned down from its ori- gin, in order to bring the next muscles into view. Nerve-supply. —Inferior gluteal branch of the lesser ischiatic nerve. The GLUTEUS MEDIUS is placed in front of, rather than beneath, the gluteus maximus ; andj is covered in by a process of the deep fascia, which is very thick and dense. It arises from the outer surface of the ilium between the superior and middle curved lines, FiG.237.—Deepmus- cles of the gluteal region. 1. Ilium. 2. Sacrum. 3. Pos- terior sacro-iliac ligaments. 4. Tu- berosity of the is- chium. 5. Great sacro-ischiatic ligament. 6.Lesser sacro-ischiatic ligament. 7. Tro- chanter major. 8. Gluteus minimus. 9. Pyriformis. 10. Gemellus superior. 11. Obturator in- ternus, passing out of the lesser sacro- ischiatic foramen. 12. Gemellus infe- rior. i3.Quadratns femoris. 14. Ad- ductor magnus. 15. Vastus exter- nus. 16. Biceps. 17. Gracilis. 18. Semi-tendinosus. 350 GLUTEAL REGION. and from the thick fascia above mentioned. Its fibres converge to a triangular rough surface on the outer part of the trochanter major, into which its tendon is inserted. Relations.—By its superficial surface with the tensor vaginas femoris, gluteus maximus, and its own proper fascia. By its deep surface with the gluteus minimus and gluteal vessels and nerve. By its lower border with the pyriformis muscle. A bursa is inter- posed between its tendon and the upper part of the trochanter major. Nerve-supply.—Superior gluteal nerve, from the sacral plexus. This muscle should now be removed from its origin and turned down, to expose the next, which is situated beneath it. The GLUTEUS MINIMUS is a radiate muscle arising from the surface of the dorsum ilii, between the middle and inferior curved lines ; its fibres converge to the anterior border of the trochanter major, into which it is inserted by means of a rounded tendon. Relations.—By its superficial surface with the gluteus medius and gluteal vessels. By its deep surface with the ilium, long tendon of the rectus femoris, and capsule of the hip-joint. A bursa is interposed between its tendon and the trochanter. Nerve-supply.—Superior gluteal nerve. The PYRIFORMIS (pyrum, a pear), i.e., pear-shaped, arises from the anterior surface of the sacrum, by three little slips interposed between the anterior sacral foramina, from the first to the fourth, from the adjoining surface of the ilium, and from the greater sacro- ischiatic ligament. It passes out of the pelvis through the great sacro-iscliiatic foramen, and is inserted by a rounded tendon into the upper border of the trochanter major, behind the tendon of the obturator interims, with which it is often blended. Relations.—By its superficial or external surface with the sacrum and gluteus maximus. By its deep or pelvic surface with the rectum, sacral plexus of nerves, branches of the internal iliac artery, great sacro-iscliiatic notch, and capsule of the hip-joint. By its upper border with the gluteus medius and gluteal vessels and nerve. Bv its lower border with the gemellus superior, ischiatic vessels and nerves, and internal pudic vessels and nerve. Nerve-supply.—A branch from the sacral plexus. The GEMELLUS SUPERIOR (gemellus, double, twin) is a small slip of muscle situated immediately below the pyriformis ; it arises from the spine of the ischium, and is inserted into the upper border of the tendon of the obturator interims, and into the upper border of the trochanter major. The gemellus superior is not unfrequentlv wanting. Relations.—By its superficial surface with the gluteus maximus, ischiatic vessels and nerves, and internal pudic vessels and nerve. By its deep surface with the pelvis and capsule of the hip-joint. Nerve-supply.—A branch from the sacral plexus. The OBTURATOR INTERNUS arises from the inner surface of the anterior wall of the pelvis, being attached to the margin of OBTURATORS AND GEMELLI. bone around the obturator foramen and to the obturator membrane. It passes out of the pelvis through the lesser sacro-ischiatic foramen, and is inserted by a flattened tendon into the inner aspect of the upper border of the trochanter major. The lesser sacro-ischiatic notch, over which this muscle plays as through a pulley, is faced with cartilage, and provided with a synovial bursa to facilitate its movements. The tendon is most marked on the side applied to the surface of the notch, and is divided into four or five narrow portions, which have a silky sheen ; it is bordered above and below by the gemelli muscles (hence their names), which are in- serted into the sides of its tendon, and appear to be auxiliaries or superadded portions—external origins, in fact, of the obturator internus. Relations.—By its superficial or posterior surface with the in- ternal pudic vessels and nerve, the obturator fascia, which separates it from the levator ani and viscera of the pelvis, the sacro-ischiatic ligaments, gluteus maximus, and ischiatic vessels and nerves. By its deep or anterior surface with the obturator membrane and the margin of bone surrounding it, the cartilaginous pulley of the lesser ischiatic foramen, external surface nf the pelvis, and capsular ligament of the hip-joint. By its upper border within the pelvis, with the obturator vessels and nerve ; externally to the pelvis, with the gemellus superior. By its loiver border with the gemellus inferior. Nerve-supply.—A special branch of the sacral plexus. The GEMELLUS INFERIOR arises from the posterior border of the tuberosity of the ischium, and is inserted into the lower border of the tendon of the obturator internus, and into the upper border of the trochanter major. Relations.—By its superficial surface with the gluteus maximus, and ischiatic vessels and nerves. By its deep surface with the external surface of the pelvis and capside of the hip-joint. By its upper border with the tendon of the obturator internus. By its lower border with the tendon of the obturator externus and quad rat us femoris. Nerve-supply.—A branch from the sacral plexus. In this region only the tendon of the obturator externus can be seen, by pulling apart the gemellus inferior and quadratus femoris ; it is situated deeply between the gemellus inferior and upper border of the quadratus femoris. To expose the muscle fully, it is necessary to dissect it on the anterior part of the thigh, after the removal of the pectineus, adductor longus, and adductor brevis. The OBTURATOR EXTERNUS muscle (obturare, to stop up) arises from the obturator membrane and from the surface of the bone immediately surrounding it anteriorly—viz., from the ramus of the pubes and ischium ; its tendon passes outwards behind the neck of the femur, to be inserted into the digital fossa of the trochanter major. When the femur is rotated outwards the tendon of this muscle lies in the groove between the acetabulum and tuberosity of the ischium. Relations.—By its superficial or anterior surface with the tendon of the psoas and iliacus, pectineus, adductor brevis and magnus, 352 ANTERIOR FEMORAL REGION. obturator vessels and nerve. By its deep or posterior surface with the obturator membrane and margin of bone which surrounds it, the lower part of the capsule of the hip-joint and quadratus femoris. Nerve-supply.—The obturator nerve. The QUADRATUS FEMORIS (square-shaped) arises from the ex- ternal border of the tuberosity of the ischium ; and is inserted into a rough line on the posterior border of the trochanter major, which is thence named linea quadrati. [Relations.—-By its posterior surface with the gluteus maximus, and ischiatic vessels and nerves. By its anterior surface with the tendon of the obturator externus and trochanter minor, a synovial bursa often separating it from the latter. By its upper border with the gemellus inferior; and by the loicer border with the adductor magnus. Nerve-supply.—A branch from the sacral plexus. Actions.—The gluteal muscles are abductors of the thigh, when they take their fixed point from the pelvis. Taking their fixed point from the thigh, they act as extensors of the pelvis on the femur, and thus are the chief muscles by which the erect posture is maintained : they assist also in carrying the leg forward in progres- sion. The anterior fibres of the gluteus medius and minimus assisted in rotating the limb inwards. The gluteus maximus, from its fibres passing backwards to the posterior aspect of the bone, rotates the limb outwards; it is, moreover, a tensor of the fascia of the thigh, and through the agency of the ilio-tibial band acts as an extensor of the leg on the thigh. The other muscles rotate the limb outwards, everting the knee and foot; hence they are named external rotators. The obturator externus, besides being an external rotator, is also a Hexor and adductor of the thigh. Anterior Femoral Region. Tensor vaginae femoris, Sartorius, Rectus femoris, Vastus interims, Vastus externus, Crureus. Dissection.—Make an incision along the line of Poupart’s liga- ment, from the anterior superior spinous process of the ilium to the spine of the pubes ; and a second, from the inner end of the preced- ing, down the inner side of the thigh, and across the inner condyle of the femur to about two inches below the head of the tibia, where it may be hounded by a transverse incision. Turn back the integu- ment from the whole of this region, and examine the superficial fascia ; which is next to be removed in the same manner. After the deep fascia has been well considered, it is likewise to be removed, by dissecting it off in the course of the fibres of the muscles. As it might not be convenient to the junior student to expose so large a surface at once as ordered in this dissection, the vertical incision SARTORIUS. 353 may be crossed by one or two transverse incisions, as may be deemed most proper. The TENSOR VAGIN2E FEMORIS (stretcher of the sheath of the thigh) is a short flat muscle, situated on the outer side of the hip. It arises from the crest of the ilium, near its anterior superior spinous process, and from the notch be- tween the two anterior spinous processes, and is inserted between two layers of the fascia lata at about one-fourth down the thigh. Relations.—By its superficial surface with the fascia lata and integument. By its deep surface with an internal layer of the fascia lata, gluteus medius, rectus, and vastus externus. By its inner border near its origin with the sartorius. Nerve - supply. — Superior gluteal nerve. The SARTORIUS (tailor’s muscle) is a long ribbon-like muscle, arising from the anterior superior spinous process of the ilium, and from the notch immediately below that process ; it crosses obliquely the upp er third of the thigh, descends behind the inner condyle of the femur, and is inserted, by an aponeurotic expan- sion into the upper part of the inner side of the tibia, nearly as far forward as the crest. This expansion covers in the in- sertion of the tendons of the gracilis and' semi-tendinosus muscles. The inner border of the sartorius muscle is the guide to the operation for tying the femoral artery in the middle of its course, and the outer boundary of Scarpa’s triangular space. This muscle is pierced by two nerves, the middle cutaneous and the patellar branch of the long saphenous. Nerve - supply. — Anterior crural nerve. Relations.— By its superficial surface with the fascia lata and cutaneous nerves. By its deep surface with the psoas and iliacus, rectus, sheath of the femoral vessels, vastus internus, adductor longus, adductor magnus, gracilis, long saphenous nerve, internal lateral ligament of the knee-joint. By its expanded insertion with the tendons of the gracilis and semi- Fio. 238.—Muscles of the ante- rior femoral region. 1. Crest of the ilium. 2. Its anterior superior spinous process. 3. Gluteus medius. 4. Tensor vaginae femoris ; its insertion into the fascia lata is shown interiorly. 5. Sartorius. 6. Rectus. 7. Vastus extemus. 8. Vastus intemus. 9. Pat- ella. 10. Iliacus internus. 11. Psoas magnus. 12. Pec- tineus. 13. Adductor longus. 14. Part of the adductor magnus. 13. Gracilis. 354 EXTENSOR MUSCLES OF THE THIGH. tendinosus, a synovial bursa being interposed. At the knee-joint its posterior border is in relation with the internal saphena vein. SCARPA’S SPACE.—This is a triangular space of some surgical importance situated at the upper part of the thigh ; in its upper part femoral hernia takes place, and in its lower part ligature of the femoral artery is usually performed. Its base is formed by Poupart’s ligament, its inner border by the adductor longus, its outer border by the sartorius muscle, and its apex is at the point where the latter muscle crosses the artery. Its floor is formed by the iliacus, psoas, pectineus, adductor longus, and a small part of the adductor brevis. It contains the common femoral, superficial femoral, profunda femo- ris, and circumflex arteries, the superficial and profunda femoris veins, anterior crural nerve and its branches, external cutaneous nerve and deep lymphatic vessels. A perpendicular line, drawn from the middle of the base to the apex of this triangle, immediately overlies the femoral artery with its sheath. The RECTUS FEMORIS is a fusiform muscle placed in the middle of the anterior aspect of the thigh. It arises by a flattened tendon from the space between the inferior curved line of the dorsum of the ilium and the upper margin of the acetabulum, its fibres being intimately blended with the circular fibres of the capsular ligament of the hip, and with the cotyloid ligament; this is usually described as the reflected head. The muscle is also connected by means of a rounded accessory band of condensed areolar tissue with the anterior inferior spine of the ilium, and by a falciform process to about an inch of the anterior border of the ilium above the inferior spine ; this connection is generally regarded as the direct continua- tion of the muscle, and is described as the straight head. These heads are connected by a deep process of the ilio-tibial band and by areolar and adipose tissue situated between the two layers of that process of fascia. The body of the muscle is spindle-shaped, and is composed of fleshy and tendinous fibres disposed in the following manner : the superior tendon as it descends spreads out into an aponeurosis which covers the anterior surface of the upper third of the muscle, and sends a tendinous band between the fleshy fibres as far as the lower third of the thigh ; the inferior tendon, in like manner, spreads out on the back part of the muscle, so as to form an aponeurosis which covers the lower two-tliirds of that aspect. Between these two the fleshy fibres pass, being arranged in a penni- form manner, those in the middle of the thigh being connected anteriorly with the tendinous band above described as originating from the upper aponeurosis. The lower tendon becomes narrowed a few inches above the patella into a flat band which receives on its borders the attachment of some fibres of the vastus externus and interims, and is inserted into the anterior edge of the upper surface of the patella. Relations.—By its superficial surface with the gluteus medius, psoas and iliacus, sartorius ; and for the lower three-fourths of its extent with the fascia lata. By its deep surface with the capsule VASTUS MUSCLES. 355 of the hip-joint, external circumflex vessels, crureus, vastus internus and externus. Nerve-supply.—Anterior crural nerve. The rectus must now be divided through its middle, and the two ends turned aside to bring clearly into view the next muscles. The VASTUS EXTERNUS arises from the upper end of the spiral line of the femur as far inwards as the external cervical tubercle, from the inferior border of the great trochanter (where that process joins the shaft of the bone), from the line leading from the great trochanter to the linea aspera, from the outer lip of the latter as far down as its bifurcation, and from the external intermuscular septum. At the point of its attachment where it lies against the insertion of the gluteus maximus, it becomes blended with the tendon of that muscle, and where the two muscles glide over each other a bursa is interposed. The greater part of the superficial surface is aponeurotic, this being usually the case with the upper three-fourths, excepting the anterior border ; the fleshy fibres run downwards and slightly forwards, passing from the superficial aponeurosis to one situated on the deep aspect of the muscle and derived from the tendon of insertion. The lower fleshy fibres are more oblique than the upper ; they are inserted into a narrow thick tendon which is intimately connected with the crureus and rectus ; from this tendon fibrous expansions are given off to blend with similar processes derived from the other extensor muscles, and form a fibrous capsule, which passes over the lateral aspect of the front of the knee-joint and is inserted into the head of the tibia. The tendon of insertion gives off an aponeurosis which lines the deep surface of the muscle for the lower half of its extent; traced downwards the tendon is found to be inserted into the upper half of the outer border of the patella. It is often difficult to define the anterior edge of this muscle, and to distinguish its fibres from those of the crureus, but the line of separation is almost invariably indicated by the course of the ex- ternal circumflex vessels, and the nerve passing to the muscle itself. Relations.—By its superficial surface with the fascia lata, rectus, biceps, semi-membranosus, and gluteus maximus. By its deep surface with the crureus and femur. Nerve-supply.—Anterior crural nerve. The VASTUS INTERNUS arises from the spiral line of the femur, from the internal cervical tubercle to the point where that line joins the linea aspera, and from the inner border of the latter as far as the groove for the femoral artery. As was observed with the vastus externus, the superficial portion of the muscle is chiefly aponeurotic, excepting at the lower third of the thigh, where it becomes fleshy. The fleshy fibres below the groove for the artery spring from the rounded tendon of insertion of the adductor magnus and the fibrous membrane which unites that tendon with the internal supracondylar line. The fibres of the vastus internus are connected at their origin with those of the adductor muscles ; they lie upon and clothe the 356 EXTENSOR MUSCLES OF THE THIGH. inner surface of the femur, but are not attached to it. The muscle is inserted by a tendon common to it, the crureus, vastus externus and rectus, into the front of the inner half of the base of the patella, but the lower fibres pass directly to the inner border of that bone without joining the tendon, and from this latter portion of the muscle an aponeurosis is prolonged to be inserted immediately below the inner tuberosity of the tibia, some of its fibres joining the internal lateral ligament of the knee. In its upper part the muscle is often blended with the crureus, but their line of separation may be made out by following the course of a small nerve which is derived from the upper branch to the vastus internus, and passes down between the vastus internus and crureus to be distributed to the subcrureus and upper part of the synovial pouch of the knee. Relations.—By its superficial surface with the psoas and iliacus, rectus, sartorius, femoral artery and vein, and saphenous nerve, pec- tineus, adductor longus, brevis, and magnus, and fascia lata. By its deep surface with the crureus and femur. Nerve-supply.—Anterior crural nerve. The CRUREUS (crus, the leg) consists of four laminae, placed one over the other ; separated above, at their origin, by intervals of bare bone, but fused below. The first of these is placed superficially to the rest, and arises from the spiral line to the outer side of the" in- ternal cervical tubercle ; its attachment passes from thence down the outer surface of the bone to the gluteal ridge, and is continued downwards along the outer lip of the linea aspera and external inter- muscular septum. Below the point where the linea aspera divides, the fibres cease to arise from bone, but continue to spring from the external intermuscular septum close to its attachment to the supra- condylar line. The second layer lies beneath the first, and is attached lower down on the shaft of the femur, and the third and fourth in like manner lie beneath and below the second. Each layer arises entirely by fleshy fibres in the form of an arched process, which extends from the inner border of the shaft transversely across its front, and then obliquely down its outer surface for a short distance to the linea aspera, where it blends with the adjacent layers of the crureus, the vastus externus and external intermuscular septum. The lower two-thirds of the anterior surface of the crureus is aponeurotic, the aponeurosis being narrow below, where it lies in the middle of the limb, and spread out above, where it covers the whole of the anterior and part of the outer surface. The crureus is inserted by means of the common tendon into the upper border of the patella.* Relations.—By its superficial surface with the external circum- flex vessels, rectus, vastus internus and externus. By its deep sur- face with the femur, sub-crureus, and synovial membrane of the knee-joint. * The above description of the extensor muscles is coudensed from an exhaustive account given by Mr. W. Roger Williams, M.R.C.S., in the Journal of Anatomy and Physiology, vol. xiii. p. 204. ACTIONS OF THE EXTENSOR MUSCLES OF THE THIGH. 357 Nerve-supply.—Anterior crural nerve. The four muscles above described are often grouped under one common title as the quadriceps extensor cruris ; or, the three muscles most intimately connected, the two vasti and the crureus, receive the name of triceps femoralis. SUB-CRUREUS.—When the crureus is divided from its insertion, a small muscle is seen upon the lower part of the femur ; it generally consists of two fasciculi, external and internal, which are inserted into the pouch of synovial membrane that extends upwards from the knee-joint, behind the patella ; and is named, from its situation, mb-crureus. It draws up the synovial membrane in the act of extension of the knee-joint. Actions.—The tensor vaginae femoris renders the fascia lata tense, and rotates the limb inwards. The sartorius flexes the leg upon the thigh, and, continuing to act, the thigh upon the pelvis, at the same time rotating it outwards and carrying the leg across that of the opposite side, into the position in which tailors sit; hence its name. Taking its fixed point from below, it assists the extensor muscles in steadying the leg, for the support of the trunk. The other four muscles have been collectively named quadriceps extensor, from their similarity of action. They extend the leg upon the thigh, and obtain a great increase of power by their attachment to the patella, which acts as a fulcrum. Taking their fixed point from the tibia, they steady the femur upon the leg, and the rectus, being attached to the pelvis, serves to balance the trunk upon the lower extremity. Internal Femoral Region. Iliacus internus, Psoas magnus, Pectineus, Adductor longus, Adductor brevis, Adductor magnus, Gracilis. Dissection.—These muscles are exposed by the removal of the inner Hap of integument recommended in the dissection of the an- terior femoral region. The iliacus and psoas arising from within the abdomen can only be seen in their entire extent after the removal of the viscera from that cavity. The ILIACUS INTERNUS is a Hat radiated muscle. It arises from the fossa of the ilium, ilio-lumbar ligament, base of the sacrum, internal lip of the crest, and anterior border of the bone ; and after escaping beneath the crural arch and joining the tendon of the psoas, is inserted into the trochanter minor of the femur. A few fibres of this muscle are derived from the base of the sacrum, and others from the capsular ligament of the hip-joint. The iliacus internus and psoas magnus are so intimately blended at their insertion that they are sometimes described as a single muscle arising by two heads under the name of ilio-psoas. Relations.—By its anterior surface, within the pelvis, with the 358 external cutaneous nerve and iliac fascia, which latter separates it from the peritoneum, on the right from the caecum, and on the left from the sigmoid flexure of the colon ; externally to the pelvis, with the fascia lata, rectus, and sartorius. By its posterior surface with the iliac fossa, margin of the pelvis, and capsule of the hip-joint, a synovial bursa of large size being interposed. This bursa some- times communicates with the synovial membrane of the ilio-femoral articulation. By its inner border, with the psoas magnus and an- terior crural nerve. Nerve-supply.—Anterior crural nerve. The iliac fascia is the aponeurotic investment of the psoas and iliacus muscle ; and, like the transversalis fascia, is thick below, and becomes gradually thinner as it ascends. It is attached superiorly, along the edge of the psoas, to the anterior lamella of the aponeurosis of the transversalis muscle, to the ligamentum arcuatum internum, and to the bodies of the lumbar vertebra?, leaving arches correspond- ing with the constricted part of the vertebrae for the transit of the lumbar vessels. Lower down it passes beneath the external iliac vessels, and is attached along the margin of the true pelvis ; ex- ternally it is connected to the crest of the ilium ; and, inferiorly, to the outer two-thirds of Poupart’s ligament, where it is continuous with the transversalis fascia. Passing beneath Poupart’s ligament, it surrounds the psoas and iliacus muscle to its termination, and beneath the inner part of the femoral arch forms the posterior segment of the crural canal and sheath of the femoral vessels. The PSOAS MAGNUS (y/soa, lumbus, a loin), situated by the side of the vertebral column in the loins, is a long fusiform muscle. It arises from the bodies and bases of transverse processes of the last dorsal and all the lumbar vertebrae. It also takes its origin from the intervertebral substance, and from a series of tendinous arches attached to the vertebrae, and intended for the protection of the lumbar vessels and branches of the sympathetic nerve in their passage between the muscle and the bone. From this extensive origin the muscle passes along the margin of the brim of the pelvis, and beneath Poupart’s ligament, to its insertion. The tendon of the psoas magnus is joined by the iliacus, and inserted into the posterior part of the trochanter minor, a bursa being interposed. Relations.—-By its anterior surface with the ligamentum arcuatum internum of the diaphragm, kidney, psoas parvus, genito-crural nerve, sympathetic nerve, psoas fascia, peritoneum, colon, and along its pelvic border, the common and external iliac artery and vein. By its posterior surface with the lumbar vertebrae, lumbar arteries, quad- ratus lumborum (from which latter it is separated by the anterior layer of the aponeurosis of the transversalis), and crural nerve, which, near Poupart’s ligament, reaches its outer side. The lumbar plexus of nerves is situated in the substance of the posterior part of the muscle. In the thigh the muscle is in relation with the fascia lata in front; the border of the pelvis and hip-joint, from which it is separated by the synovial membrane, common to it and the preced- INTERNAL FEMORAL REGION. ADDUCTOR MUSCLES. 359 ing muscle, behind; the crural nerve and iliacus muscle to the outer side ; and the femoral artery, by which it is slightly overlaid, to the inner side. Nerve-supply.—Branches from the lumbar plexus. The PECTINEUS is a flat and quad- rangular muscle; it arises from the pectineal line (peden, a crest) of the os pubis, and from the surface of bone in front of that line. It is inserted into the ridge leading from the lesser tro- chanter to the linea aspera of the femur. Relations.—By its anterior surface with the pubic portion of the fascia lata, which separates it from the femo- ral artery and vein and internal saphe- nous vein, and lower down with the profunda artery. By its posterior sur- face with the capsule of the hip-joint, obturator externus, and adductor brevis, the obturator vessels being interposed. By its external border with the psoas, the femoral artery resting on the line of interval. By its internal border with the outer edge of the adductor longus. Obturator hernia is situated directly behind this muscle, which forms one of its coverings. Nerve - supply. — This muscle re- ceives one branch from the anterior crural, and another from the obturator. The ADDUCTOR LONGUS (adducere, to draw to), the most superficial of the three adductors, arises by a round and thick tendon from the front surface of the os pubis,' immediately below the angle of that bone ; and, assuming a flattened and expanded form as it descends, is inserted into the middle third of the inner lip of the linea aspera. Relations.—By its anterior surface with the pubic portion of the fascia lata, and near its insertion, with the femoral artery and vein. By its posterior surface with the adductor brevis and magnus, anterior branches of the obturator vessels and nerve, and, near its insertion, profunda artery and vein. By its outer border with the pectineus ; by the inner border with the gracilis. Pig. 239.—1. Femur. 2. Ilium. 3. Pubes. 4. Obturator ex- ternus. 5. Upper portion of adductor magnus. 6. Upper portion of adductor brevis. 7. Lower part of the same muscle. 8. Middle portion of adductor magnus, partly covered by ad- ductor brevis. 9. Lower part of adductor magnus, terminat- ing in a round tendon, 10. 11. Opening for femoral artery. 12. Opening for the passage of the internal circumflex vessels. 360 ADDUCTOR MUSCLES. The pectineus must be divided near its origin and turned outwards, and the adductor longus through its middle, turning its ends to either side, to bring into view the adductor brevis. Nerve-supply.—Obturator nerve. The ADDUCTOR BREVIS, placed behind the pectineus and ad- ductor longus, is fleshy, and thicker than the adductor longus ; it arises from the body of the os pubis, and is inserted into the line leadiim from the lesser trochanter to the linea aspera, immediately behind the insertion of the pectineus. Nerve-supply.—Obturator nerve. Relations.—By its anterior surface with the pectineus, adductor longus, and anterior branch of the obturator nerve and artery. By its 'posterior surface with the adductor inagnus. By its outer border with the obturator externus, and tendon of the psoas and iliacus. By its inner border with the gracilis and adductor magnus. It is pierced near its insertion by the middle perforating artery. The adductor brevis may now be divided from its origin and turned outwards, or its inner two-thirds may be cut away entirely, when the adductor magnus muscle will be exposed in its entire extent. The ADDUCTOR MAGNUS is a broad triangular muscle, forming a septum of division between the muscles situated on the anterior and those on the posterior aspect of the thigh. It arises by fleshy fibres from the ramus of the pubes and ischium and from the ante- rior border of the tuber ischii ; and radiating in its passage out- wards, is inserted into the line leading from the great trochanter to the linea aspera, to the whole length of the middle lip of the linea aspera, and by a rounded tendon into a small spine on the inner condyle of the femur. The adductor magnus is pierced by five openings ; the three superior, for the three perforating arteries ; the fourth, for the termination of the profunda. The fifth is the large oval opening, in the tendinous portion of the muscle, that gives passage to the femoral vessels. Relations.—Bv its anterior surface with the pectineus, adductor brevis, adductor longus, femoral artery and vein, and profunda artery and vein, with their branches. By its posterior surface with the semi-tendinosus, semi-membranosus, biceps, and gluteus maxi- mus. By its inner border with the gracilis and sartorius. By its upper border with the obturator externus and quadratus femoris. Nerve-supply.—Obturator nerve. The GRACILIS (slender) is situated along the inner border of the thigh. It arises by a broad but very thin tendon, from the bodv of the os pubis along the edge of the symphysis ; and from the margin of the ramus of the pubes and ischium ; it is inserted by a rounded tendon into the upper part of the inner side of the tibia, nearly as far forwards as the crest, beneath the expansion of the sartorius. Relations.—By its inner or superficial surface with the fascia lata, and below with the sartorius and internal saphenous nerve ; the internal saphena vein crosses it, lying superficially to the fascia lata. IIAM-STRINCr MUSCLES. 361 By its outer or deep surface with the adductor longus, brevis, and magnus, and the internal lateral ligament of the knee-joint, from which latter it is separated by a synovial bursa common to it and the tendons of the gracilis and semi-tendinosus. Nerve-supply.—Obturator nerve. Actions.—The iliacus, psoas, pectineus, and adductor longus muscles flex the thigh upon the pelvis, and at the same time, from the obliquity of their insertion into the lesser trochanter and linea aspera, rotate the limb outwards ; the pectineus and adductors ad- duct the thigh powerfully, and from the manner of their insertion into the linea aspera, assist in rotating the limb outwards. The gracilis is an adductor of the thigh ; but contributes to the ilexion of the leg, by its attachment to the tibia. Posterior Femoral Region.—Ham-string Muscles. Biceps femoris, Semi-tendinosus, Semi-membranosus. Dissection.—Remove the integument and fascia from the posterior part of the thigh by two flaps, and turn aside the gluteus maximus from the upper part ; the muscles may then be examined. The BICEPS FEMORIS (flexor cruris) arises by two heads, one (long head) by a common tendon with the semi-tendinosus from the lower and inner part of the tuber ischii; the other (short head), muscular and much shorter, from the lower two-thirds of the external border of the linea aspera, external supracondylar ridge, and external intermuscular septum. The short head reaches as high as the in- sertion of the gluteus maximus. The biceps forms the outer ham- string, and is inserted by a strong tendon into the head of the fibula ; one portion of the tendon being continued downwards into the fascia of the leg, and another being attached to the outer tuberosity of the tibia. At its insertion into the fibula the tendon divides into two portions, between which the long external lateral ligament of the knee passes, a synovial bursa being interposed. Relations.—By its superficial or posterior surface with the gluteus maximus and fascia lata. By its deep or anterior surface with the semi-membranosus, adductor magnus, vastus externus, from which it is separated by the external intermuscular septum, great iscliiatic nerve, popliteal artery and vein, and near its insertion the external head of the gastrocnemius and plantaris. By its inner border with the semi-tendinosus, and in the popliteal space with the popliteal artery and vein. Its tendon of insertion has the external popliteal nerve in immediate relation with it posteriorly. Nerve-supply.—Great sciatic nerve. The SEMI-TENDINOSUS, remarkable for its long tendon, arises in common with the long head of the biceps, from the lower and inner part of the tuberosity of the ischium : the two muscles being closely united for several inches below their origin. It is inserted into the 362 HAM STRING MUSCLES. upper part of trie inner side oi the tibia, nearly as far forwards as the crest, immediately below the insertion of the tendon of the gra- cilis, and sends an expansion to the fascia of the leg. Relations.—By its superficial surface with the gluteus maximus, fascia lata, and at its insertion with the synovial bursa which sepa- rates its tendon from the expansion of the sartorius. By its deep surface with the semi-membranosus, adductor magnus, internal head of the gastrocnemius, and internal lateral ligament of the knee-joint, the synovial bursa common to it and the tendon of the gracilis being interposed. By its inner border with the gracilis ; by its outer border with the biceps. Nerve - supply.—Great sciatic nerve. These two muscles must be dissected from the tube- rosity of the ischium, to bring into view the origin of the next. The SEMI-MEMBRANO- SUS, remarkable for the ten- dinous expansion upon its an- terior and posterior surface, arises from the upper and outer facet on the tuberosity of the ischium, external to the common origin of the two preceding muscles. It is in- serted into the posterior part of the inner tuberosity of the tibia; at its insertion the tendon splits into three portions, one of whicli is in- serted in a groove on the inner side of the head of the tibia, beneath the inter- nal lateral ligament. The second is continuous with an aponeurotic expansion that binds down the popliteus muscle, the popliteal fascia; and the third turns upwards and outwards to the external condyle of the femur, forming the middle portion of the posterior ligament of the knee- joint (ligamentum posticum Winslowii). The tendons of the semi-tendinosus, semi-membranosus, gracilis, and sartorius form the inner hamstring. Relations.—By its superficial surface with the gluteus maximus, biceps, semi-tendinosus, fascia lata, and at its insertion, the tendi- Fjo. 240. — Mus- cles of the pos- terior femoral and gluteal re- gion. 1. Glu- teus medius. 2. Gluteus maxi- mus. 3. Vastus externus cover- ed in by fascia lata. 4. Long head of biceps. 5. Short head. 6. Semi-tendi- nosus. 7, 7. Semi - membra- nosus. 8. Gra- cilis. 9. Part of the inner border of the adductor magnus. 10. Edge of sarto- rius. 11. Popli- teal space. 12. Gastrocne- mius ; its two heads. The ten- don of the bi- ceps forms the outer ham - string, the sar- torius with the tendons of the gracilis, semi- tendinosus and semi - membra- nosus, theinner hamstring. TIBIALIS ANTICUS. 363 nous expansion of the sartorius. By its deep surface with the quad- ratus femoris, adductor magnus, internal head of gastrocnemius, knee-joint (from which it is separated by a synovial membrane), and the popliteal artery and vein. By its inner border with the gracilis. By its outer border with the great ischiatic nerve, and in the popliteal space the popliteal artery and vein. Nerve-supply.—Great sciatic nerve. If the semi-membranosus muscle be turned down from its origin, the student will bring into view the broad and radiated expanse of the adductor magnus, against which the three flexor muscles above described rest. Actions.—The three ham-string muscles are flexors of the leg upon the thigh ; and taking their fixed point from below they extend the pelvis, and balance it on the lower extremities. The biceps, from the obliquity of its direction, everts the leg when partly flexed, and the semi-tendinosus turns the leg inwards when in the same state of flexion. Oleland has pointed out that the ham-string muscles limit flexion at the hip as long as the knee is extended ; so that it is only by flexing the leg on the thigh that it is possible completely to flex the thigh on the abdomen. Anterior Tibial Region. Tibialis anticus, Extensor longus digitorum, Peroneus tertius, Extensor proprius hallucis. Dissection.—The dissection of the anterior tibial region is to be commenced by carrying an incision along the middle of the leg midway between the tibia and fibula, from the knee to the ankle, and bounding it interiorly by a transverse incision extending from one malleolus to the other. To expose the tendons on the dorsum of the foot, the longitudinal incision may be carried onwards to the outer side of the base of the great toe, and terminated by another incision directed across the heads of the metatarsal bones. The TIBIALIS ANTICUS arises from the outer tuberosity and upper two-thirds of the outer surface of the tibia, the interosseous membrane, intermuscular fascia, and deep fascia ; its tendon passes through a distinct sheath in the anterior annular ligament close to the inner border of the tibia, and is inserted into the inner and under side of the internal cuneiform bone, and base of the metatarsal bone of the great toe. Eelations.—By its anterior surface with the deep fascia from which many of its superior fibres arise, and the anterior annular ligament. By its posterior surface with the interosseous membrane, tibia, ankle-joint, and bones of the tarsus. By its internal surface with the tibia ; by its external surface with the extensor longus digito- rum; extensor proprius hallueis, and anterior tibial vessels and nerve. 364 EXTENSOR MUSCLES OF THE LEG. Nerve-supply.—Anterior tibial nerve. The EXTENSOR LONGUS DIGITORUM (extensor communis longus) arises from the outer tuberosity of the tibia, the head and upper three-fourths of the fibula, the interosseous membrane, intermuscular fascia, and deep fascia. Near the ankle it divides into four tendons, which pass beneath the annular ligament through a proper tendinous pulley (the sling ligament of Retzius), to be inserted into the second and third phalanges of the four lesser toes. The mode of insertion of the extensor tendons is remarkable; each ten- don spreads into a broad aponeurosis over the base of the first pha- lanx ; this aponeurosis is strengthened on its borders by the tendons of the extensor brevis digitorum, lumbricales and interossei, and di- vides into three slips ; the middle slip is in- serted into the base of the second phalanx, the two lateral slips are con- tinued onwards, to be inserted into the base of the third. Relations.—By its anterior surface with the deep fascia of the leg and foot, and anterior annular ligament. By its ‘posterior surface with the interosseous mem- brane, fibula, ankle - joint, extensor brevis digitorum (which sepa- rates its tendons from t he tarsus), metatarsus, and phalanges. By its inner surface with the tibialis anticus, extensor proprius hallucis, and anterior tibial vessels. By its outer border with the peroneus longus and brevis. Nerve-supply.—This muscle and the next are both supplied by the anterior tibial nerve. The PERONEUS TERTIUS arises from the lower fourth of the inner surface of the fibula and intermuscular fascia, and is inserted into the upper surface of the base of the metatarsal bone of the little toe. Although anmrentlv but a mere division or continuation of Fig. 241. — Muscles of the anterior tibial region. 1. Quadriceps exten- sor inserted into the patella; the figure rests on the tendon of the rec- tus, the vastus internus and ex- ternus are situ- ated one at each side. 2. Subcu- taneous surface of the tibia. 3. Tibi- alis anticus. 4. Extensor longus digitorum. 5. Ex- tensor proprius hallucis. 6. Pero- neus tertius. 7. Peroneus longus. 8. Peroneus brevis, g, 9. Borders of the soleus muscle. 10. Part of the in- ner belly of the gastrocnemius. 11. Extensor brevis digitorum ; the tendon in front of the number is that of £he peroneus tertius; that be- hind it, the pero- neus brevis. EXTENSOR PROPRIUS HALLUCIS. 365 the extensor longus digitorum, this muscle may be looked upon as homologous to the flexor carpi ulnaris of the forearm. Sometimes it is wanting. The EXTENSOR PROPRIUS HALLUCIS lies between the tibialis anticus and extensor longus digitorum. It arises from the middle three-fifths of the fibula and interosseous membrane. Its tendon passes through a distinct sheath in the annular liga- ment, and is inserted into the base of the last phalanx of the great toe, being closely connected with the first pha- lanx by short fibrous bands. Relations.—By its anterior surface with the deep fascia of the leg and foot, and anterior annular ligament. By its ■posterior surface with the interosseous membrane, fibula, tibia, ankle-joint, ex- tensor brevis digitorum, and bones and articulations of the great toe. It is crossed on this aspect by the anterior tibial vessels and nerve. By its outer side with the extensor longus digitorum, and in the foot with the dorsalis pedis artery and veins ; the outer side of its tendon on the dorsum of the foot being the guide to these vessels. By its inner side with the tibialis anticus, and anterior tibial vessels. Nerve-supply.—Anterior tibial nerve. Actions.—The tibialis anticus and peroneus tertius are direct flexors of the tarsus upon the leg. The two tibial muscles acting together raise the inner border of the foot and draw it inwards. They assist also in preserving the arch of the foot during progres- sion. The extensor longus digitorum and extensor proprius hallucis are extensors of the phalanges ; and continuing their action, they assist the tibialis anticus and peroneus tertius in flexing the foot upon the leg. Taking their origin from below, they increase the stability of the ankle-joint. Fig. 242.—Insertion of extensors of toes. 1. Extensor proprius hallucis. 2, 2. Fibrous bands passing to first phalanx of great toe. 3. Fibrous bands from 4, Extensor longus digitorum. Posterior Tibial Region. Superficial Group. Gastrocnemius, Plantaris, Soleus. Dissection.—Make an incision from the middle of the popliteal space down the middle of the posterior part of the leg to the heel, hounding it interiorly by a transverse incision passing below the two malleoli. Turn aside the flaps of integument and remove the 366 MUSCLES OF THE CALF OF THE LEG. fasciae from the whole of this region ; the gastrocnemius muscle will then be exposed. The GASTROCNEMIUS (yao-TpoKvrjfuov, the bellied part of the leg) arises by two heads from the rough surfaces above the back part of the two condyles of the femur, the inner head being the longest. The tendons of origin are intimately connected with the posterior ligament of the knee-joint, and are lined on their anterior surface by the synovial membrane. They unite to form the beauti - ful muscle so characteristic of this region of the limb. It is inserted, by means of the tendo- Achillis, into the lower part of the posterior tuberosity of the os calcis, a synovial bursa being placed between the tendon and the upper part of the tubero- sity. The gastrocnemius must be removed from its origin, and turned down in order to expose the next muscle. Relations. — By its super- ficial surface with the deep fascia of the leg, which sepa- rates it from the external saphena vein, and with the external saphenous nerve. By its deep surface with the lateral portions of the posterior liga- ment of the knee-joint, the popliteus, plantaris, and soleus. The internal head of the muscle rests against the pos- terior surface of the internal condyle of the femur, and is separated from the semi-mem- branosus by a synovial bursa which often communicates with the cavity of the knee-joint. The external head rests against the outer side of the external condyle, and often has in it a sesamoid bone or fibro-cartilage. Nerve-supply.—Internal popliteal nerve. The PLANTARIS (planta, the sole of the foot), an extremely diminutive muscle situated between the gastrocnemius and soleus, arises from the upper and back part of the outer condyle of the femur ; and is inserted, by its long and delicately slender tendon, into the inner side of the posterior tuberosity of the os calcis, by the side of the tendo-Achillis, having crossed obliquely between Fio. 243.—Super- ficial muscles of the posterior aspect of the leg. 1. Biceps, forming the outer ham- string. 2. Ten- dons, forming the inner ham- string. 3. Pop- liteal space. 4. Gastrocnemius. 5, 5. Soleus. 6. Tendo-Achillis. 7. Posterior tu- berosity of the os calcis. 8. Tendons of the peroneus lon- gus and brevis passing behind the outer ankle. 9. Tendons of the tibialis pos- ticus and flexor longus digito- rum passing into the foot behind the in- ner anl{;le. SOLEUS AND POPLITEUS. 367 the two muscles. It corresponds to the palmaris longus in the forearm. Nerve-supply.—Internal popliteal nerve. The SOLEUS {solea, a sole) is the broad muscle upon which the plantaris rests. It arises from the head and upper half of the fibula, from the oblique line and middle third of the inner border of the tibia, and from a tendinous arch thrown across between these two portions. Its fibres converge to the tendo-Acliillis, by which it is inserted into the posterior tuberosity of the os calcis. The tendinous arch gives passage to the popliteal vessels and nerve in their course to the leg. Relations.—By its superficial surface with the gastrocnemius and plantaris. By its deep surface with the intermuscular fascia, which separates it from the flexor longus digitorum, tibialis posticus, flexor longus hallucis, posterior tibial vessels and nerve, and pero- neal vessels. Nerve-supply.—Internal popliteal. Actions.—The three muscles of the calf draw powerfully on the os calcis, and lift the heel; continuing their action they raise the entire body. This movement is attained by means of a lever of the second power, the fulcrum (the toes) being at one end, the weight (the body supported on the tibia) in the middle, and the power (these muscles) at the other extremity. They are, therefore, the walking muscles, and perform all move- ments that require the support of the whole body from the ground, as dancing, leaping, &c. Taking their fixed point from below, they steady the leg upon the foot. The gastrocnemius is also a powerful flexor of the leg on the thigh. Deep Layer. Popliteus, Flexor longus hallucis, Flexor longus digitorum, Tibialis posticus. Dissection.—After the removal of the soleus, the deep layer will be found bound down by an intermuscular fascia which is to be dissected away ; the muscles may then be exandned. The POPLITEUS muscle (poples, the ham of the leg) forms the floor of the popliteal region at its lower part, and is bound tightly down by a strong fascia derived from the middle slip of the tendon of the semi-membranosus muscle. It arises by a rounded tendon from a deep groove at the outer side of the external condyle of the femur, beneath the external lateral ligament and within the capsular ligament of the joint; and spreading obliquely over the head of the tibia, is inserted into the surface of the bone above its oblique line. This line is sometimes called, from being the limit of insertion of the popliteus muscle, the popliteal line. During flexion of the limb, the tendon of origin of this muscle lies in the groove on the outer side of the external condyle of the femur. It is homologous with the pronator radii teres in the forearm. FLEXOR MUSCLES OF THE LEG. Relations.—By its superficial surface with a thick fascia which separates it from the gastrocnemius, plantaris, and popliteal vessels and nerve. By its deep surface with the synovial membrane of the knee-joint, and upper part of the tibia. Nerve-supply.—Internal popiiteal. The FLEXOR LONGUS HALLUCIS is the most superficial of the next three muscles. It arises from the lower two-thirds of the internal surface of the fibula excepting about an inch at its lowest part, and passes through a groove in the astragalus and os calcis, converted by tendinous fibres into a distinct sheath lined by synovial membrane, into the sole of the foot, to be inserted into the base of the last phalanx of the great toe. Relations. — By ii> superficial surface with the intermuscular fascia, which separates it from the soleus and tendo-Achillis. By its deep surface with the tibialis posticus, fibula, peroneal vessels, inter- osseous membrane, and ankle-joint. By its outer border with the peroneus longus and brevis. By its inner border with the flexor longus digitorum. In the foot, the tendon of the flexor longus pol- licis is connected with that of the flexor longus digi- torum by a short tendinous slip. Nerve - supply. — Pos- terior tibial nerve. The FLEXOR LONGUS DIGITORUM (flexor perforans) arises from the posterior surface of the tibia, extending from the oblique line to within three inches of the inner ankle. Its tendon passes through a sheath, common to it and the tibialis posticus, behind the inner malleolus ; it then passes through a second sheath which is con- nected with a groove in the astragalus and os calcis into the sole of the foot, where it divides into four tendons, which are inserted into the base of the last phalanx of the four lesser toes, perforating the tendons of the flexor brevis digitorum. Fig. 244.—Deep layer of muscles of the posterior tibial re. gion. 1. Lower ex- tremity of the femur. 2. Ligamentum posti- cum Winslowii. 3. Tendon of the semi- membranosus muscl e dividing, into three slips. 4. Internal lateral ligament of the knee-joint. 5. External lateral liga- ment. 6. Popliteus muscle. 7. Flexor longus digitorum. 8. Tibialis posticus. 9. Flexor longus hal- iucis. 10. Peroneus longus. 11. Peroneus brevis. 12. Tendo- Achillis divided near its insertion into t he os calcis. 13. Ten- dons of the tibialis posticus and flexor longus digitorum, just as they are about to pass beneath the internal annular liga- ment of the ankle ; the interval between the latter tendon and the t tendon of the flexor longus liallucis is for the posterior tibial vessels and nerve. TIBIALIS POSTICUS. 369 Relations.—By its superficial surface with the intermuscular fascia, which separates it from the soleus, and with the posterior tibial vessels and nerve. By its deep surface with the tibia and tibialis posticus. In the sole of the foot its tendon is in relation with the abductor hallucis and flexor brevis digitorum, which lie super- ficially to it, and it crosses the tendon of the flexor longus hallucis. At the point of crossing it receives a tendinous slip of communi- cation. Nerve-supply.—Posterior tibial. Dissection.—The flexor longus hallucis must now be removed from its origin, and the flexor longus digitorum drawn aside, to bring into view the entire extent of the tibialis posticus. The TIBIALIS POSTICUS lies upon the interosseous membrane, between the two bones of the leg. It arises by two heads from the adjacent sides of the tibia and fibula their whole length except about two inches at the lower end, from the interosseous membrane, and from an aponeurosis which binds it in its place. Its tendon passes inwards beneath the tendon of the flexor longus digitorum, and runs in the same sheath ; it then passes through a proper sheath over the deltoid ligament, and beneath the astragalo-scaphoid articulation, to be inserted into the tuberosity of the scaphoid and internal cunei- form bone, a process of its tendon being prolonged outwards to the external cuneiform, and other processes being connected with the middle cuneiform, the cuboid, and the bases of the second, third, and fourth metatarsal bones. While in the common sheath behind the internal malleolus, the tendon of the tibialis posticus lies internally to that of the flexor longus digitorum, from which it is separated by a thin fibrous par- tition. A sesamoid bone is usually met with in the tendon close to its insertion. Relations.—By its superficial surface with the intermuscular septum, flexor longus hallucis, flexor longus digitorum, posterior tibial vessels and nerve, peroneal vessels, and in the sole of the foot the abductor hallucis. By its deep surface with the interosseous membrane, fibula and tibia, ankle-joint and astragalus. The anterior tibial artery passes between the two heads of the muscle. Nerve-supply.—Posterior tibial. The student will observe that the two latter muscles change their relative position to each other in their course. Thus, in the leg, the position of the three muscles from within outwards is, flexor Fig. 245.—Relations of parts behind the inner malleolus. 1, 1. Tibialis posticus. 2. Tendo-Achillis. 3. Tibialis anticus. 4, 4. Flexor longus digitorum. 6. Pos- terior tibial artery. 8. Posterior tibial nerve. The tendon of the flexor longus hallucis is too deeply placed to be shown in this view. 370 FIBULAR REGION. longus digitorum, tibialis posticus, flexor longus hallucis. At the inner malleolus, the relation of the tendons is, tibialis posticus, flexor longus digitorum, both in the same sheath ; then a broad groove, which lodges the posterior tibial artery, venae comites, and nerve ; and lastly, the flexor longus hallucis. Actions.—The popliteus is a flexor of the tibia upon the thigh, carrying it at the same time inwards so as to invert the leg, the joint being so arranged that rotation is only possible when the leg is Hexed. It is especially brought into play at the commencement of flexion of the knee, producing the inward rotation of the tibia (or outward rotation of the femur), which is essential to that action. The flexor longus hallucis and flexor longus digitorum are the long flexors of the toes ; their tendons are connected in the foot by a short tendinous band, hence they necessarily act together. The tibialis posticus is an extensor of the tarsus upon the leg, and in this respect is an antagonist to the tibialis anticus. It combines with the tibialis anticus in adduction of the foot. Fibular Region. Dissection.—These muscles are exposed by continuing the dissec- tion of the anterior tibial region outwards beyond the fibula to the border of the posterior tibial region. The PERONEUS LONGUS (nepovri, fibula) arises from the head and upper two-thirds of the outer side of the fibula, from the deep fascia and intermuscular septa, and terminates in a long tendon which passes behind the external malleolus, and obliquely across the sole of the foot, through the groove in the cuboid bone (converted into a canal by a fibrous band), to be inserted into the outer side of the base of the metatarsal bone of the great toe and under surface of the internal cuneiform bone. Its tendon is thickened where il glides behind the external malleolus, and a sesamoid bone is de- veloped in that part which plays against the cuboid bone. Relations.—By its superficial surface with the fascia of the leg and foot. By its deep surface with the fibula, peroneus brevis, os calcis, cuboid bone, and, near the head of the fibula, the external popliteal nerve. By its anterior border it is separated from the extensor longus digitorum by the attachment of the fascia of the leg to the fibula ; and, by the posterior border, by the same medium from the soleus and flexor longus hallucis. The tendon of the peroneus longus is furnished with three fibrous sheaths and as many synovial membranes ; the first is situated behind the external malleolus, and is common to this muscle and the peroneus brevis, the second at the outer side of the os calcis, the third on the cuboid bone. Nerve-supply.—Musculo-cutaneous nerve, a branch of the pero- neal nerve. The PERONEUS BREVIS 1 ies beneath the peroneus longus ; it Peroneus longus, Peroneus brevis. MUSCLES OF FOOT. arises from the lower two-thirds of the external surface of the shaft of the tibula and intermuscular septa, and terminates in a tendon which passes behind the external malleolus and through a groove in the os calcis, to be inserted into the outer side of the base of the metatarsal bone of the little toe. Relations.—By its superficial surface with the peroneus longus and fascia of the leg and foot. By its deep surface with the tibula, os calcis, and cuboid bone. The lateral relations of the muscle are the same as those of the peroneus longus. The tendon of the peroneus brevis has but two tendinous sheaths and two synovial membranes, one being behind the external malleolus and common to both peronei, the other at the side of the os calcis. Nerve-supply.—Musenlo-cutaneous nerve. Actions.—The peronei muscles are extensors of the foot, con- jointly with the tibialis posticus. They antagonise the tibialis anticus and peroneus tertius, which are ttexors of the foot; they also raise the outer border of the foot and draw it outwards. The whole of these muscles acting together, tend to maintain the arch of the foot, so necessary to security in walking. FOOT. Dorsal Region. Extensor brevis digitorum, Dorsal interossei. The EXTENSOR BREVIS DIGITORUM muscle arises from the outer side of the os calcis, the external calcaneo-astragaloid ligament, and the lower part of the an- terior annular ligament; it crosses the foot obliquely, and terminates in four tendons, the innermost of which is inserted into the base of the first phalanx of the great toe, and the other three into the outer side of the long extensor tendons of the second, third, and fourth toes. Relations.—By its upper surface with the tendons of the extensor longus digi- torum, peroneus brevis, and the deep fascia of the dorsum of the foot. By its under surface with the tarsal and metatarsal bones, and dorsal interossei muscles. Its inner border is in relation with the dorsalis pedis artery, the innermost tendon crossing that artery just before its division. Nerve-supply.—Anterior tibia! nerve. 1 he DORSAL INTEROSSEI muscles, four in number, are placed Fig. 246. —Diagram of the dorsal interosseous muscles of the foot; designed to show that they all abduct from the middle line of the second toe. 37 2 between the metatarsal bones ; they resemble the corresponding muscles in the hand in arising by two heads from the adjacent sides of the metatarsal bones ; their tendons are inserted into the base of the first phalanx, and the digital expansion of the tendons of the long extensor. The dorsal interossei muscles all abduct from the middle line of the second toe. The tendon of the first is inserted into the inner side of the base of the first phalanx of the second toe, the other tendons into the outer side of the first phalanges of the second, third, and fourth toes. Nerve-supply.—External plantar nerve. Relations.—By their upper surface with a strong fascia which separates them from the extensor tendons. By their under surface with the plantar interossei. Each of the muscles gives passage to a small artery (posterior perforating) which communicates with the external plantar artery ; and between the heads of the first inter- osseous muscle the dorsalis pedis artery takes its course. PLANTAR REGION. Plantar Region. First Layer. Abductor hallucis, Abductor minimi digit!, Flexor brevis digitorum. Dissection.—The sole of the foot is best dissected by carrying an incision around the heel and along the inner and outer border of the foot, to the great and little toe. This incision should divide the integument and superficial fascia, and both together should be dis- sected from the deep fascia, as far forward as the base of the pha- langes, where they should be removed from the foot altogether. The plantar fascia should then be raised by a transverse incision made through it at about the middle of the foot, and should be turned over towards the toes; the first layer of muscles will thus be brought into view. The ABDUCTOR HALLUCIS lies along the inner border of the foot; it arises by two heads, between which the tendons of the long flexors, arteries, veins, and nerves enter the sole of the foot. One head proceeds from the inner tuberosity of the os calcis, the other from the internal annular ligament and plantar fascia ; it is inserted along with the inner head of the flexor brevis hallucis into the base of the first phalanx of the great toe, and into the internal sesamoid bone. Relations.—By its superficial surface with the internal portion of the plantar fascia. By its deep surface with the flexor brevis hallucis, flexor accessorius, tendons of the flexor longus digitorum, flexor longus hallucis, tibialis anticus and posticus, plantar vessels and nerves, and tarsal bones. At its outer border with the flexor brevis digitorum, from which it is separated by a vertical septum of the plantar fascia. Nerve-supply.—Internal plantar nerve. The ABDUCTOR MINIMI DIGITI lies along the outer border of the sole of the foot. It arises from the outer tuberosity of the os cal- cis, the surface between the two tuberosities, the external intermuscular septum, and from the plantar fascia as far for- ward as the base of the fifth metatarsal bone ; and is inserted with the flexor brevis into the base of the first phalanx of the little toe. Relations. — By its superficial surface with the external portion of the plantar fascia. By its deep surface with the flexor accessorius, flexor brevis minimi digiti, tarsal bones, and meta- tarsal bone of the little toe. By its inner side with the flexor brevis digitorum, from which it is separated by the vertical septum of the plantar fascia. Nerve-supply.—External plantar nerve. The FLEXOR BREVIS DIGITORUM (perforatus) is placed between the two preceding muscles. It arises from the under surface of the os calcis, from the plantar fascia, and intermuscular septa ; and is inserted by four tendons into the base of the second phalanx of the four lesser toes. Each tendon divides, previously to its insertion, to give passage to the tendon of the long flexor; hence its cognomen perforatus. Relations.—By its superficial surface with the plantar fascia. By its deep surface with a thin layer of fascia which separates it from the flexor accessorius, tendons of the flexor longus digitorum and flexor longus liallucis, and plantar vessels and nerves. By its borders with the vertical septa of the plantar fascia which separate the muscle, on the one side from the abductor hallucis, and on the other from the abductor minimi digiti. Nerve-supply.—Internal plantar nerve. FLEXOR BREVIS DIGITORUM 373 Fig. 247. — First layer of muscles of the sole of the foot; this layer is exposed by the re- moval of the plan- tar fascia. 1. Os calcis. 2. Posterior part of the plan- tar fascia divided transversely. 3. Abductor hallu- cis. 4. Abductor minimi digiti. 5. Flexor brevis digi- torum. 6. Tendon of the flexor long- us hallucis. 7, 7. Lumbricales. On the second and third toe, the ten- dons of the flexor longus digitorum are seen passing through the bifur- cation of the ten- dons of the flexor brevis digitorum. Second Layer. Flexor accessorius, Lumbricales Dissection.—The three preceding muscles must be divided near 374 their origin, and turned downwards, in order to see the muscles of this group, but they must not be entirely removed. The FLEXOR ACCESSORIUS arises by two slips, the inner of which is fleshy and the outer tendinous ; the former is attached to the inner surface of the os calcis, and the latter to the under surface of the same bone a little in front of the outer tuberosity, and to the long plantar ligament. It is inserted into the outer border, and upper and lower surfaces of the long flexor tendon. Relations. — By its superficial sur- face with the three muscles of the superficial layer, from which it is separated by their fascial sheaths, and with the external plantar vessels and nerve. By its deep surface with the under part of the os calcis and long plantar ligament. Nerve - supply. —External plantar nerve. The LUMBRI - CALES (lumbricus, an earth - worm) are four little muscles arising from the tendons of the flexor longus digitorum at their point of bifurca- tion, each, with the exception of the most internal, being attached to two tendons ; they are inserted into the expansion of the extensor tendons, and the base of the first phalanx of the four lesser toes on their inner side. They pass between the digital slips of the plantar fascia to their insertion. Nerve-supply.—The two inner by digital branches of the internal plantar nerve, the two outer by the deep branch of the external plantar. PLANTAR REGION. Fig. 248. — Deep muscles of the sole of the foot. I. Sheath of flexor longus hallucis. 2. Os calcis. 3. Sheath of flexor longus digitorum. 4. Long plantar ligament. 5. Sheath of tibi- alis posticus. 6. Tendon of peroneus lon- gus. 7. Flexor brevis hallucis. 8. Flexor brevis minimi digiti. 9. Tendon of abductor hallu- cis. 10. Trans- versus pedis. II. Adductor hallucis. 12. Tendon of flex- or brevis digi- torum to fourth toe. 13. Tendon of flexor longus hallucis. 14. Tendon of flex- or longus digi- torum to fourth toe. THIRD LAYER OF MUSCLES. 375 Third Layer. Transversus pedis, Flexor brevis minimi digiti. Flexor brevis hallucis, Adductor hallucis, Dissection.—The tendons of the long flexors and the muscles con- nected with them must be removed, to see clearly the attachments of the third layer. The FLEXOR BREVIS HALLUCIS arises by a pointed tendinous process from the side of the cuboid, external cuneiform bone, and expanded tendon of the tibialis posticus ; it is inserted by two heads into the outer and inner sides of the base of the first phalanx of the great toe. Two sesamoid bones are developed in the tendons of insertion of these two heads, and the tendon of the flexor longus hallucis lies in the groove between them. Relations.—By its superficial surface with the abductor hallucis, tendon of the flexor longus hallucis, and plantar fascia. By its deep surface with the tarsal bones, metatarsal bone of the great toe, and insertion of the tendon of the peroneus longus. By its inner border with the abductor hallucis ; and by its outer border with the adductor hallucis ; with both of which muscles it is blended near its insertion. Nerve-supply.—Internal plantar nerve. The ADDUCTOR HALLUCIS arises from the cuboid bone, the sheath of the tendon of the peroneus longus, and the base of the third and fourth metatarsal bones. It is inserted into the base of the first phalanx of the great toe, in conjunction with the outer head of the flexor brevis hallucis. Relations.—By its superficial surface with the tendons of the flexor longus and flexor brevis digitorum, flexor accessorius, and lumbricales. By its deep surface with the tarsal bones and ligaments, external plantar artery and veins, interossei muscles, tendon of the peroneus longus, and metatarsal bone of the great toe. By its inner border with the flexor brevis hallucis, with which its fibres are blended. Nerve-supply.—External plantar. The TRANSVERSUS PEDIS arises by fleshy slips from the inferior metatarso-phalangeal ligaments of the three outer toes, and from the transverse ligament. It passes transversely inwards to be inserted into the base of the first phalanx of the great toe, its tendon being blended with that of the adductor hallucis. Relations.—By its superficial surface with the tendons of the flexor longus and flexor brevis digitorum, and lumbricales. By its deep surface with the interossei and ligaments of the metatarso- phalangeal articulations. Nerve-supply.—External plantar. The FLEXOR BREVIS MINIMI DIGITI arises from the base of the metatarsal bone of the little toe, and the sheath of the tendon of the peroneus longus. It is inserted into the base and external border of the first phalanx of the little toe. Relations.—By its superficial surface with the tendons of the 376 PLANTAR INTEROSSEI. flexor longus and flexor brevis digitorum, the fourth lumbricalis, abductor minimi digiti, and plantar fascia. By its deep surface with the plantar interosseous muscle of the fourth metatarsal space, and the fifth metatarsal bone. Nerve-supply.—External plantar. Fourth Layer The PLANTAR INTEROSSEI muscles are three in number, and are placed upon rather than between the metatarsal bones. They arise from the base and inner side of the shaft of the metatarsal bone of the three outer toes, and are inserted into the inner side of the extensor tendon and base of the first phalanx of the same toes. The plantar interosseous all draw towards the middle line of the second toe, the dorsal draw from that line ; hence the former are abductors, the latter adductors. A like arrangement exists in the hand, with this difference, that the middle finger is the one through which the central line is drawn. Actions.—The muscles of the foot cor- respond generally with those of the hand, and their actions are indicated by their names. It may, however, be noticed that, while the long flexor muscles are flexors of the toes, they are extensors of the foot at the ankle-joint, and in like manner the extensors of the toes are flexors of the ankle. The flexor accessorius is not represented in the hand ; its use is to modify the line of action of the long flexor, so as to bring it into the direction of the middle of the foot, and of the short flexor muscle. It is probable that the adductor hallucis cor- responds to the inner head of the flexor brevis pollicis of the hand, the trans- versus pedis being the time adductor ; and the nerve-supply of these muscles furnishes confirmation of that view. The great toe has a very slight range of movement com- pared with the thumb, and although it has corresponding muscles, has no opponent power ; that is to say, it cannot be so placed as to face the other toes, as the thumb can to the lingers. The interossei and lumbricales, like those of the hand, are flexors of the first phalanges and extensors of the two last. Plantar interossei. Fig. 249. — Diagram of the plantar interosseous mus- cles, designed to show that they are all adductors to the middle line of the second toe. PART V. ANGIOLOGY. In the section on Histology two sets of vessels have been described, namely, those carrying blood and those carrying lymph, and the former have further been divided into arteries, veins, and capillaries. The description of the capillaries can, however, only be satisfactorily given in connection with the organs of which they form a part, so that their arrangement and distribution will not now occupy our attention. The present section will therefore be devoted to the description of the arteries, veins, and lymphatics. ARTERIES. In the consideration of the arteries, the aorta will be first de- scribed, with the branches of that trunk and their subdivisions, which together constitute the efferent portion of the systemic circula- tion ; and then the pulmonary artery as the efferent trunk of the pulmonary circulation. AORTA. The aorta arises from the base of the left ventricle, at the middle of the root of the heart on a level with the body of the sixth dorsal vertebra, and presents at its commencement an enlargement caused by three dilatations of the walls of the vessel, the sinuses of Val- salva, and corresponding with the three semilunar valves. It ascends at first forwards and to the right, then curves backwards and to the left, and descends on the left side of the vertebral column to the fourth lumbar vertebra. Hence it is divided into the arch, descending or thoracic, and abdominal aorta. The arch of the aorta, commencing at a point corresponding with the articulation of the cartilage of the third rib with the sternum on the left side, crosses behind and near the sternum to a point corresponding with the upper border of the articulation of the second rib with the sternum on the right side. It then curves backwards and to the left, and descends to the left side of the body 378 of the fifth dorsal vertebra, and at the lower border of the latter vertebra becomes the thoracic aorta. The first or ascending portion of the arch, a little more than two inches in length, is almost wholly contained within the pericardium ; it extends from the third costal cartilage of the left side, to the upper border of the second cartilage of the right side, at its junc- tion with the sternum. It has in front the pulmonary artery, right auricular appendix, pericardium and thymus gland ; on its left side the pulmonary artery ; on its right the right auricle and superior vena cava; and behind the right pulmonary artery and veins. The second or transverse portion of the arch is directed back- wards and to the left, and extends from the second costal cartilage on the right side to the left side of the body of the fourth dorsal vertebra. It has in front, the left pleura and lung, remains of thymus gland, left phrenic nerve, left superior cardiac nerve, left inferior cardiac of the pneumogastric, left pneumogastric nerve, and left superior intercostal vein. Behind it is in relation with the trachea, oesophagus, thoracic duct, deep cardiac plexus, and left re- current laryngeal nerve. Above it gives off the arteria innominata, left carotid and left subclavian artery, and has lying on it the left vena innominata ; and below is in relation with the superficial cardiac plexus, bifurcation of the pulmonary artery, cord of the ductus arteriosus, left bronchus, and left recurrent nerve. The third or descending portion of the arch lies the fifth dorsal vertebra, and is partially covered by the left pleura. It is in relation in front with the pleura and root of the left lung, behind with the body of the fifth dorsal vertebra, on the right side with the (esophagus and thoracic duct, and on the left with the pleura. Descending Aorta.—The descending aorta is subdivided, in cor- respondence with the two great cavities of the trunk, into the thoracic and abdominal aorta. Thoracic Aorta.—The thoracic aorta, commencing at the lower border and left side of the fifth dorsal vertebra, curves gently towards the right as it descends, and as it passes through the aortic opening of the diaphragm lies on the middle line of the vertebral column in front of the last dorsal vertebra. It is in relation behind, with the vertebral column and lesser vena azygos ; in front, with the oesophagus, left pulmonary artery, left bronchus, pericardium, and right pneumogastric nerve ; to the left side, with the pleura, left lung, and oesophagus ; and to the right, with the oesophagus, vena azygos major, and thoracic duct. Abdominal Aorta.—The aorta enters the abdomen through a special opening in the diaphragm, and, as it lies against the body of the last dorsal vertebra, receives the name of abdominal aorta; it passes downwards, and on the fourth lumbar vertebra, a little to the left of the middle line, divides into the two common iliac arteries. Its relations and branches will be described on a later page. AORTA. HEART AND GREAT VESSELS. Fig. 250.—Heart and great vessels. 1. Anterior belly of digastric. 2. Submental artery. 3. Submaxillary gland. 4. Mylo-hyoid. 5. External carotid. 6. Hyoid bone. 7. Internal carotid. 8. Thyro-hyoid. 9. Thyroid cartilage. 10. Superior thyroid artery, n. Right common carotid. 12. Crico-thyroid. 13. Thyroid body. 14. Cricoid cartilage. 15. Inferior thyroid artery. 16. Left common carotid. 17. Thyroid axis. 18. Trachea. 19. Vertebral artery. 20. Left subclavian artery. 21. Right subclavian artery. 22. Internal mammary artery. 23. Innominate artery. 24. Upper lobe of left lung. 25. Upper lobe of right lung. 26. Arch of aorta. 27. Middle lobe of right lung. 28. Pulmonary artery. 29. Lower lobe of right lung. 30. Right auricle. 31. Diaphragm. 32. Front of right ventricle. 34. Lower lobe of left lung. 380 AORTA. Branches.—The branches of the aorta, arranged in a tabular form are as follows :— Arch ascending portion, Coronary, right and left. transverse portion, Innominate artery, Left carotid, Left subclavian, Pericardiac, Bronchial, (Esophageal, Intercostal. ( Right carotid, [ Right subclavian. Phrenic, Gastric, Hepatic, Splenic. Thoracic aorta Coeliac axis Abdominal aorta Supra-renal, Renal, Superior mesenteric, Spermatic, Inferior mesenteric, Lumbar, Sacra-media, Common iliacs. Varieties of the Aorta.—The aorta seldom deviates from the course and relations above described. In some few cases there is persistence of the double arch which exists in the early stages of the development of the vascular system, and in rare instances the aortic arch turns to the right side instead of the left, this being frequently accompanied by complete transposition both of the thoracic and abdominal viscera. Varieties in the primary branches of the arch are by no means uncommon. That which is by far the most frequent is the origin of the left vertebral from the arch ; next in frequency we have the origin of both carotids and the right subclavian in common from the innominate, so that the primary branches of the transverse arch are reduced to two. Occasionally there is absence of the innominate, all four branches arising directly from the arch ; in such cases the order in which the branches are generally given off is, right common carotid, left carotid, left subclavian, right sub- clavian, the last artery passing behind the trachea and oesophagus to reach its proper position behind the right sterno-clavicular joint. The CORONARY ARTERIES arise from the two anterior of the three aortic sinuses at the commencement of the ascending portion of the arch of the aorta, immediately above the free margin of the semilunar valves. The left coronary (usually the larger of the two) passes forwards, between the pulmonary artery and left auricular appendix, and divides into two branches ; one of which (posterior) winds around the base of the left ventricle in the auriculo-ventricular groove, and reaches nearly as far as the corresponding branch of the right coronary ; the other (anterior) passes along the groove of union of the two ventricles, on the anterior aspect of the heart, to its apex, giving off branches in its course to the ventricular walls. The left INNOMINATE ARTERY. coronary artery supplies the left auricle and anterior surface of both ventricles. The right coronary passes forwards, between the root of the pulmonary artery and the right auricle, and runs from left to right in the auriculo-ventricular groove. It gives off a small branch which continues onwards transversely, between the left auricle and ventricle ; the main trunk descends along the posterior aspect of the heart to its apex, giving off' twigs which supply the posterior aspect of both ventricles. The coronary arteries anastomose with each other on the surface of the heart, and by the branches distributed to the walls of the great vessels; but in the walls of the heart their branches are for the most part “ terminal' arteries,” without anastomoses. 381 INNOMINATE ARTERY. The innominate artery (brachio-cephalic) (Fig. 2 50, 23) is the first and largest artery given off by the arch of the aorta. It is an inch and a half in length, and arises from the arch behind the junction of the first and second pieces of the sternum ; it ascends obliquely towards the right sterno-clavicular articulation, where it divides into the right carotid and right subclavian artery. Plan of the Relations of the Innominate Artery. In Front. Sternum, Sterno-hyoid muscle, Sterno-thyroid muscle, Remains of thymus gland, Left brachio-cephalic vein, Right inferior thyroid veins, Inferior cervical cardiac branch of right vagus. Right Side. Right brachio-cephalic vein, Right vagus nerve, Pleura. Left Side. Remains of thymus, Left common carotid artery, Left inferior thyroid vein, Trachea. Innominate Artery. Behind. Trachea. The innominate artery occasionally gives off a small branch, thyroidea ima (lowest thyroid), which ascends along the middle of the trachea to the thyroid gland. A knowledge of its existence is important in performing the operation of tracheotomy. COMMON CAROTID ARTERIES. The common carotid arteries (icapa, the head) arise, the right from the bifurcation of the innominate artery opposite the right sterno- 382 COMMON CAROTID ARTERY. clavicular articulation, the left from the arch of the aorta. It follows, therefore, that the right, carotid is shorter than the left; it is also more anterior ; and, in consequence of proceeding from a branch instead of from the main trunk, is larger than its fellow. The right common carotid artery (Fig. 250, 11) ascends the neck perpendicularly by the side of the trachea and larynx, from behind the right sterno-clavicular articulation to a level with the upper border of the thyroid cartilage, where it divides into the ex- ternal carotid and internal carotid. The left common carotid (Fig. 250, 16) passes somewhat ob- liquely outwards from the arch of the aorta to the side of the neck, and thence upwards by the side of the trachea and oesophagus to a level with the upper border of the thyroid cartilage, where it divides like the right common carotid into the external carotid and internal carotid. Relations.—The common carotid artery, in the neck, is enclosed in a fibrous sheath, which also contains the internal jugular vein, lying to the outer side of the artery, and the vagus nerve, which lies between and behind both. The sheath rests on the vertebral column, having interposed the sympathetic nerve and anterior muscles of the vertebral column, and being crossed behind by the inferior thyroid artery and recurrent laryngeal nerve. Plan of Relations of the Common Carotid Artery. In Front. Integument and fascia, Platysma, Superior thyroid veins, Lingual and facial veins, Sterno-mastoid, Sterno-hyoid, Sterno-tliyroid, Omohyoid, Descendens cervicis nerve. Internally. Ti-achea, Thyroid gland, Larynx, Pharynx, Recurrent laryngeal nerve, Inferior thyroid artery. Externally. Internal jugular vein, Pneumogastric nerve. Common Carotid Artery. Behind. Longus colli, Rectus anticus major, Sympathetic nerve, Inferior thyroid artery, Recurrent laryngeal nerve. EXTERNAL CAROTID ARTERY. 383 In Front. Left brachio-cephalic vein, Remains of thymus gland, Sternum. Additional Relations of the Left Common Carotid. Behind. Trachea, Thoracic duct. Internally. Innominate artery, (Esophagus. Externally. Pleura, EXTERNAL CAROTID ARTERY. The external carotid artery ascends nearly perpendicidarly from opposite the upper border of the thyroid cartilage, to the space between the neck of the lower jaw and meatus auditorius, where it divides into two terminal branches, temporal and internal maxillary. Superficial aspect. Integument and fascia, Platysma, Digastric, Stylo-liyoid, Hypoglossal nerve, Facial nerve, Temporo-maxillary vein, Parotid gland. Plan of the Relations of the External Carotid Artery. Deep aspect. Stylo-pliaryngeus, Stylo-glossus, Glosso-pharyngeal nerve, Parotid gland. External Carotid Artery. Anteriorly. Hyoid bone, Pharynx. Parotid gland, Kamus of jaw. Branches.—The branches of the external carotid, nine in num- ber, may he arranged into three groups, anterior, posterior, and ascending. They are as follows :— Anterior. Superior thyroid, Lingual, Facial. Posterior. Occipital, Posterior auricular. Ascending and Terminal. Ascending pharyngeal, Parotidean, Temporal, Internal maxillary. The anterior branches arise from the commencement of the external carotid, within a short distance of each other. The lingual and facial not unfrequentlv arise from a common trunk. The SUPERIOR THYROID ARTERY, the first of the branches of the external carotid, arises from that trunk just below the great cornu of the hyoid bone and curves downwards to the thyroid gland. It is distributed by several large branches to the anterior part of the gland, and anastomoses with its fellow of the opposite side, and with SUPERIOR THYROID ARTERY. the infei'ior thyroid arteries. In its course it passes beneath the omo-hyoid, sterno-thyroid, and sterno-hyoid muscles. Branches.— Hyoid, Superior laryngeal, Sterno-mastoid. Inferior laryngeal, Muscular, Glandular. The hyoid branch passes iorward beneath the thyro-hyoid muscle, and is distributed to the depressor muscles of the hyoid bone near their insertion. It an- astomoses with its fellow of the opposite side, and with the hyoid branch of the lingual. The superior laryn- geal pierces the thyro- hyoid membrane, in company with the supe- rior laryngeal nerve, and supplies the mucous membrane and muscles of the larynx, sending a branch upwards to the epiglottis. The sterno-mastoid is commonly a branch of this trunk, although it sometimes comes off directly from the exter- nal carotid. It curves downwards and out- wards across the carotid sheath to the anterior margin of the sterno- mastoid muscle, to which and to the neighbour- ing muscles and integu- ment, it is distributed. The inferior laryn geal or crico-thyroid is a small branch which crosses the crico-thyroid membrane along the lower border of the thyroid cartilage. It sends branches through that membrane to supply the mucous lining oi the larynx, and inosculates with its fellow of the opposite side. The muscular branches are distributed to the depressor muscles of the hyoid bone and larynx. Numerous glandular branches are distributed to the lateral lobes Fig. 251.—Carotid arteries with the branches of the external carotid. 1. Common carotid. 2. External carotid. 3. Internal carotid. 4. Carotid foramen in the petrous portion of the temporal bone. 5. Superior thyroid. 6. Lingual. 7. Facial. 8. Sterno- mastoid. 9. Occipital. 10. Posterior auricular. 12. Internal maxillary. 13. Temporal. 14. Ascending pharyngeal. LINGUAL ARTERY. 385 of the thyroid gland, forming a free anastomosis in its substance with the branches of the inferior thyroid. The LINGUAL ARTERY ascends obliquely from its origin ; it then passes forwards parallel with the great cornu of the hyoid hone ; thirdly, it ascends to the under surface of the tongue ; and fourthly, runs forward in a serpentine direction to its tip, under the name of ranine artery, where it terminates by being distributed to the muscles and mucous membrane of the tongue. Relations.—The first part of its course rests on the middle con- strictor muscle of the pharynx, being covered in by the tendon of the digastricus and the stylo-hvoid muscle ; the second is situated between the middle constrictor and hyo-glossus muscle, the latter separating it from the hypoglossal nerve ; in the third part of its course it lies between the hyo-glossus and genio hyo-glossus ; and in the fourth (ranine), rests on the lingualis to the tip of the tongue. Branches.—Hyoid, Dorsalis linguae, Sublingual, Ranine. The hyoid branch runs along the upper border of the os hyoides, and is distributed to the elevator muscles of the os hyoides near Fig. 252.—Lingual artery and branches. 1. Stylo-glossus muscle. 2. Ranine artery. 3. Dorsalis lingu* artery. 4. Genio-hyo-glossus muscle. 5. Middle constrictor. 6. Genio-hyoid muscle. 7, 7. Hyo-glossus (cut). 8. Sublingual artery. 9. Ex- ternal carotid artery. 11. Lingual artery. 13. Hyoid branch. their insertion, inosculating with its fellow of the opposite side, and with the hyoid branch of the superior thyroid when that branch is present. The dorsalis linguse springs from the artery beneath the hyo- glossus ; it ascends along the posterior border of the liyo-glossus muscle to the dorsum of the tongue, and is distributed to the tongue, fauces, and epiglottis; anastomosing with its fellow of the oppo- site side. The sublingual branch runs forward on the genio-hyo-glossus muscle, and is distributed to the sublingual gland, mucous mem- 386 BRANCHES OF EXTERNAL CAROTID ARTERY. brane of the floor of the mouth, and muscles of the tongue. It is situated between the mylo-liyoid and genio-hyo-glossus, generally accompanies Wharton’s duct for a part of its course, and sends a branch to the frsenum linguae. The latter branch affords the hemor- rhage which sometimes follows the operation of snipping the fraenum in children. The ranine artery may be looked on as the true continuation of the lingual; it runs forwards beneath the tongue, resting upon the lingualis muscle, having the genio-hyo-glossus to its inner side, and is covered by mucous membrane. It distributes numerous small branches to the substance of the tongue, but does not, as is generally stated, anastomose with its fellow of the opposite side. Hyrtle has proven by experimental injections that there is no communication between the arteries of the two sides, and this fact is substantiated by the experience of surgeons, who find that the longitudinal section of the tongue in the middle line is unaccompanied by arterial hemorrhage. FACIAL ARTERY.—The facial artery (maxillaris externa) arises immediately above the lingual and a little above the great cornu of the hyoid bone, and passes forwards to the submaxillary gland, in which it lies embedded. It then curves around the body of the lower jaw, close to the anterior inferior angle of the masseter muscle, ascends to the angle of the mouth, and thence to the angle of the eye, where it is named angular artery. The facial artery is tortuous in its course over the buccinator muscle to accommodate itself to the movements of the jaw. Relations.—Below the jaw it passes beneath the digastricus and stylo-hyoid muscles ; on the body of the lower jaw it is covered by the platysma myoides, and at the angle of the mouth by the de- pressor anguli oris and zygomatic muscles. It rests on the sub- maxillary gland, lower jaw, buccinator, orbicularis oris, levator anguli oris, levator labii superioris proprius, and levator labii supe- rioris alaeque nasi. Its branches may be grouped into those which are given off below the jaw, and those on the face ; they may be thus arranged :— Below the Jaw. Ascending palatine, Tonsillar, Submaxillary, Submental, Muscular. On the Face. Muscular, Buccal, Inferior labial, Inferior coronary, Superior coronary, Lateral nasal, Angular. The inferior or ascending palatine branch ascends between the stylo-glossus and stylo-pliaryngeus muscles, to be distributed to the styloid muscles, Eustachian tube, tonsil and soft palate, and anasto- FACIAL ARTERY. moses with the descending palatine branch of the internal maxillary artery. The tonsillar branch ascends by the side of the pharynx, and pierces the superior constrictor muscle to be distributed to the tonsil, and root of the tongue. The submaxillary are four or five branches which supply the submaxillary gland. The submental branch runs forward on the mylo-liyoid muscle, under cover of the body of the lower jaw, distributes branches to the submaxillary gland, and muscles attached to the lower jaw, and anastomoses with branches of the sublingual, inferior labial, and mental arteries. The muscular branches beneath the jaw are distributed to the internal pterygoid, digastric, and stylo-hyoid, and those on the face to the masseter and buccinator. The buccal branches, eight or ten in number, are given off upon the face, and are distributed to the buccinator, masseter, muscles of the upper lip, orbicularis palpebrarum, and integument of the cheek. They anastomose with the buccal branch of the internal maxillary, the transverse facial, and infraorbital. The inferior labial branch passes forward beneath the depressor anguli oris muscle, and is distributed to the muscles of the lower lip, inosculating with the labial branch of the inferior dental, the inferior coronary, and submental. It is frequently derived from the next branch. The inferior coronary branch is given off at the angle of the mouth, and passes inwards near the edge of the lower lip, lying between the orbicularis and mucous membrane ; it inosculates with its fellowr of the opposite side. The superior coronary branch, arising close to, or in common with, the preceding, takes its course in the same manner along the upper lip, inosculating with its fellow' of the opposite side. At the middle of the lip it sends a small branch upwards to the septum of the nose (arteria septi). The lateral nasal branch is given off near the ala nasi, and passes beneath the levator labii superioris alseque nasi, to be distributed to the nose. It inosculates with the nasal branch of the ophthalmic artery, the infraorbital, and its fellow' of the opposite side. Tin- angular is the termination of the facial artery ; it inosculates at the inner side of the orbit with the nasal branch of the ophthal- mic artery. The inosculations of the facial artery are numerous—namely, with the sublingual branch of the lingual, ascending pharyngeal artery, descending palatine artery, inferior dental at its escape from the mental foramen, infraorbital at the infraorbital foramen, buccal branches of the internal maxillary on the surface of the buccinator, transverse facial on the side of the face, and nasal and frontal branches of the ophthalmic artery at the angle of the eye. The facial artery is subject to variety in length : it not unfre-' 388 quently terminates at the angle of the nose or mouth, and is rarely symmetrical on both sides of the face. The OCCIPITAL ARTERY, smaller than the anterior branches, passes backwards behind the parotid gland and beneath the posterior belly of the digastric, trachelo-mastoid, and sterno-mastoid to the occipital groove in the mastoid portion of the temporal bone. It then ascends between the splenius and complexus, pierces the tra- pezius, and is distributed to the back of the head, anastomosing with the opposite occipital, posterior auricular, and temporal arteries. The hypoglossal nerve curves around this artery opposite the angle of the jaw and near its origin from the external carotid. The occi- pital artery is sometimes derived from the ascending cervical of the thyroid axis, or from the internal carotid. Branches.—It gives off several muscular branches to the sterno- mastoid, digastric, stylo-hyoid, and deep muscles in its course, a small branch to the external ear, and two larger branches, inferior meningeal and princeps cervicis. The inferior meningeal ascends by the side of the internal jugular vein, and passes through the jugular foramen, to be dis- tributed to the dura mater. The arteria princeps cervicis is a large and irregular branch. It descends the neck between the complexus and semi-spinal is colli, and inosculates with the deep cervical of the subclavian and with branches of the vertebral. This branch is the means of estab- lishing an important collateral circulation between the branches of the carotid and subclavian, after ligature of the common carotid artery. A small mastoid branch enters the skull through the mastoid foramen, and is distributed to the dura mater. The POSTERIOR AURICULAR ARTERY arises from the external carotid, above the level of the digastric and stylo-hyoid muscles, and ascends by the side of the stvloid process and behind the parotid gland, to the back part of the concha. It is distributed by two branches to the external ear (auricular branch), and side of the head (occipital branch), anastomosing with the occipital and temporal artery ; some of its branches pass through fissures in the fibro-cartilage to reach the anterior surface of the pinna. Branches.—The posterior auricular gives off a branch to the digastric muscle, and several branches to the parotid gland ; it then gives off the stylo-mastoid, which enters the stylo-mastoid foramen to be distributed to the aqmcductus Fallopii, labyrinth, mastoid cells, and tympanum ; a twig accompanies the chorda tympani under the name of tympanica superior. One branch of the stylo-mastoid artery forms with the anterior tympanic artery an anastomic circle round the drum of the ear. The ASCENDING PHARYNGEAL ARTERY, the smallest of the branches of the external carotid, arises from that trunk near its origin (or at the point of bifurcation of the common carotid), and ascends to the base of the skull. BRANCHES OF EXTERNAL CAROTID ARTERY. TEMPORAL ARTERY. 389 This artery has behind it, the vertebral column, rectus anticus major muscle, and superior laryngeal nerve; in front, the stylo- pharyngeus muscle ; on the inner side, the pharynx ; on the outer side, the internal carotid artery and superior cervical ganglion of the sympathetic. Its branches are :— Pharyngeal, Prevertebral, Meningeal. The pharyngeal branches are distributed to the muscles and mucous membrane of the pharynx, extending upwards to the soft palate, tonsils, and Eustachian tube, and downwards nearly to the commencement of the oesophagus. The prevertebral branch pierces the prevertebral fascia and is distributed to the rectus anticus muscles, superior cervical ganglion of the sympathetic, and ninth, tenth, and eleventh pairs of nerves. It anastomoses with the ascending cervical artery. The inferior meningeal branches pass through the jugular fora- men or anterior condylar foramen, and often through the fibrous tissue closing the middle lacerated foramen ; they end in the dura mater. The PAROTIDEAN ARTERIES are four or five large branches Avhich are given off from the external carotid whilst in the parotid gland. They are distributed to the structure of the gland, their terminal branches reaching the integument of the side of the face, and masseter muscle. The TEMPORAL ARTERY is one of the two terminal branches of the external carotid. It ascends over the root of the zygoma ; and at about an inch and a half above the zygomatic arch, divides into an anterior and 'posterior temporal branch. The anterior temporal is distributed over the front of the temple and arch of the skull, and anastomoses with the opposite anterior temporal and with the supraorbital and frontal artery. The posterior temporal curves upwards and backwards, and inosculates with its fellow of the opposite side, with the posterior auricular and occipital arteries. The trunk of the temporal artery is covered by the parotid gland and attrahens auriculam muscle, and rests on the temporal fascia. The branches of the temporal artery are—some small offsets to the parotid gland and articulation of the lower jaw, and the fol- lowing :— Anterior auricular, Transverse facial, Middle temporal. The anterior auricular branches, two in number, are distributed to the anterior portion of the pinna. The transverse facial arises from the temporal immediately below the zygoma, and runs transversely across the face, resting on the masseter muscle, and lying parallel with and a little above Stenson’s duct. It anastomoses with the facial and infraorbital arteries. BRANCHES OF EXTERNAL CAROTID ARTERY. 390 The middle temporal branch passes through an opening in the temporal fascia immediately above the zygoma into the substance of the temporal muscle, and sends small branches to that muscle, in- osculating with the deep temporal arteries. It gives off a small orbital branch which passes forward immediately above the zygoma, between the two layers of the temporal fascia, and inos- culates beneath the orbicularis palpebrarum, with the lachrymal branch of the ophthalmic artery. The INTERNAL MAXILLARY ARTERY, the other terminal branch of the external carotid, lias next to be examined. Dissection.—The internal maxillary artery passes inwards behind the neck of the lower jaw to the deep structures in the face ; we re- quire, therefore, to remove several parts for the purpose of seeing it completely. To obtain a good view of the vessel, the zygoma should Fin. 253.—Diagram of the branches of the internal maxillary artery. 1. External carotid. 2. Superficial temporal, s. Internal maxillary. 4. Anterior tympanic. 5. Middle meningeal. 6. Inferior dental. 7. Lesser meningeal. 8. Masseteric. 9. Posterior temporal. 10. Pterygoid. 11. Anterior temporal. 12. Buccal. 13. Infraorbital. 14. Spheno-palatine. 15. Descending palatine. 16. Superior dental. 17. Vidian. 18. Pterygo-palatine. be sawn across in front of the external ear, and the malar bone near the orbit. Turn down the zygomatic arch with the masseter muscle. In doing this, a small artery and nerve will be seen crossing the sig- moid notch of the lower jaw to enter the masseter muscle (masseteric). Saw through the ramus of the jaw on a level with the crowns of the molar teeth, and divide the neck of the condyle with cutting forceps, then turn the eoronoid process with the insertion of the temporal muscle upwards towards the skull ; some vessels will be seen enter- ing the under surface of the muscle ; these are the deep temporal. If the artery lies beneath the external pterygoid muscle, it will be necessary to disarticulate the condyle of the jaw and turn it inwards, together with the muscle itself. The artery and the deep branches of the inferior maxillary nerve will be seen lying against the internal INTERNAL MAXILLARY ARTERY. pterygoid muscle. These are to be carefully freed from fat and areolar tissue, and then examined. The internal maxillary artery commences in the substance of the parotid gland, opposite the meatus auditorius externus ; it passes in the first instance horizontally forward behind the neck of the lower jaw ; next, curves around the lower border of the external pterygoid muscle near its insertion, and ascends obliquely forwards upon the outer side of that muscle ; it then passes inwards between the two heads of the external pterygoid, and enters the spheno-maxillary fossa. Occasionally it takes its course between the two pterygoid muscles, without appearing on the outer surface of the external pterygoid. For the purposes of description it admits of division into three portions : maxillary, pterygoid, and spheno-maxillary. Relations.—The maxillary portion is situated between the neck of the jaw and the internal lateral ligament and inferior dental nerve, and lies parallel with the auriculo-temporal nerve ; the ptery- goid portion between the external pterygoid muscle, and the masseter and temporal muscle, or between the two pterygoid muscles. The spheno-maxillary portion lies between the two heads of the external pterygoid muscle, and, in the spheno-maxillary fossa, is in relation with Meckel’s ganglion. Branches.—Maxillary Portion. Anterior tympanic, Inferior dental, Middle meningeal, Lesser meningeal. Pterygoid Portion. Deep temporal, Pterygoid, Masseteric, Buccal. Spheno-maxillary Portion. Superior dental, Infra-orbital, Pterygo-palatine, Spheno-palatine, Descending palatine, Yidian. The anterior tympanic branch passes into the tympanum through the fissure of Glaser, and is distributed to the cavity of the tympanum and membrana tympani ; on the latter it inoscu- lates with the stylo-mastoid branch of the posterior auricular artery, and with the Yidian artery. It gives off an auricular branch to the lining membrane of the external auditory meatus and outer surface of the drum of the ear. The inferior dental descends to the dental foramen, and enters the canal of the lower jaw in company with the inferior dental nerve. Opposite the bicuspid teeth it divides into two branches, one of which is continued onwards within the bone as far as the symphysis, to supply the incisor teeth ; while the other, mental, escapes with the nerve at the mental foramen, and anastomoses with the inferior labial and submental branches of the facial. It supplies the alveoli and teeth of the lower jaw, sending small branches along the canals in their roots. At the inferior dental foramen, it gives off a m/jlo-hyoid branch, which accompanies the mylo-hyoid nerve. 392 BRANCHES OF EXTERNAL CAROTID ARTERY. Tlie middle meningeal is embraced at its origin by the two roots of the auriculo-temporal nerve ; it ascends behind the temporo- maxillary articulation to the foramen spinosum in the spinous process of the sphenoid bone, and entering the cranium, divides into an anterior and a posterior branch. The anterior branch crosses the great ala of the sphenoid to the groove or canal in the anterior inferior angle of the parietal lone, and divides into branches which ramify on the external surface of the dura mater, and anastomose with corresponding branches from the opposite side. The posterior branch crosses the squamous portion of the temporal bone, to the posterior part of the dura mater and cranium. The branches of the middle meningeal artery are distributed chiefly to the bones of the skull ; in the middle fossa it sends a small petrosal branch through the hiatus Fallopii to the facial nerve, and branches to the Gasserian ganglion. The lesser meningeal is a small branch which ascends to the foramen ovale, and passes into the skull to be distributed to the Gasserian ganglion and dura mater. It gives off a twig to the nasal fossae and soft palate. The lesser meningeal is often derived from the middle, instead of from the internal maxillary directly ;—the tympanic also occasion- ally springs from the same trunk. The muscular branches are distributed, as their names imply, to the five muscles of the maxillary region ; the deep temporal branches are two in number, anterior and posterior ; they inosculate with the middle and superficial temporal. The pterygoid branches are distributed to the two muscles of that name. The masseteric artery passes outwards, behind the tendon of the temporal muscle and over the sigmoid notch, to the masseter muscle. The buccal branch, arising opposite the anterior part of the pterygoid muscle, passes downwards with the buccal nerve to the buccinator muscle. It inosculates with the facial and transverse facial arteries. The superior dental or alveolar artery is given oft’ from the internal maxillary, just as that vessel is about to make its turn inwards to reach the spheno-maxillary fossa. It descends on the tuberosity of the superior maxillary bone, and sends its branches through several small foramina to supply the posterior teeth of the upper jaw, and the antrum. The terminal branches are continued forwards on the alveolar process, to be distributed to the gums and sockets of the teeth. The infraorbital appears, from its size, to be the proper con- tinuation of the artery. It runs along the infraorbital canal with the superior maxillary nerve, sending branches upwards into the orbit, and downwards, through canals in the bone, to supply the mucous membrane of the antrum and the teeth of the upper jaw, and emerges on the face at the infraorbital foramen. The branch which supplies the incisor teeth is the anterior dental artery; on the face the infraorbital inosculates with the facial and transverse facial arteries. The pterygo-palatine is a small branch which passes backwards through the pterygo-palatine canal, and supplies the mucous mem- brane of the posterior part of the nares, upper part of the pharynx, Eustachian tube, and sphenoidal cells. The spheno palatine, or posterior nasal, enters the superior meatus of the nose through the spheno-palatine foramen, in com- pany with the nasal filaments of Meckel’s ganglion, and divides into two branches ; one branch, arteria septi, is distributed to the mucous membrane of the septum, and inosculates in the anterior palatine canal with the terminal branch of the descending palatine ; the other supplies the mucous membrane of the lateral wall of the nares, antrum, and sphenoid and ethmoid cells. The descending palatine artery descends along the posterior palatine canal, in company with the palatine branches of Meckel’s ganglion, to the posterior palatine foramen ; it then bends forward, lying in a groove of the bone, and is distributed to the palate. While in the posterior palatine canal it sends several twigs back- wards through the small posterior palatine foramina to supply the soft palate ; anteriorly it gives off a branch, anterior palatine, which reaches the nares through the anterior palatine canal, and inosculates with the arteria septi. The Vidian or pterygoid branch passes backwards along the pterygoid canal with the nerve of the same name, and is distributed to the sheath of the nerve, the Eustachian tube, and mucous mem- brane of the upper part of the pharynx. INTERNAL CAROTID ARTERY. 393 INTERNAL CAROTID ARTERY. The internal carotid artery curves slightly outwards from the bifurcation of the common carotid, and ascends nearly perpendi- cularly by the side of the pharynx, to the carotid foramen in the petrous portion of the temporal bone. It next passes inwards, along the carotid canal, forwards by the side of the sella turcica, and upwards by the anterior clinoid process, where it pierces the dura mater, and divides into three terminal branches. The course of this artery is remarkable for the number of angular curves which it forms; one or two of these flexures are sometimes seen in the cer- vical portion, near the base of the skull; and, by the side of the sella turcica, it resembles the italic letter s, placed horizontally. Relations.—In consideration of its connections, the artery is divisible into a cervical, petrous, cavernous, and cerebral portion. Plan of the Relations of the Cervical Portion of the Internal Carotid Artery. In Front. Parotid gland, Stylo-glossus, Stylo-pharyngeus, Stylo-hyoid ligament, Glosso-pliaryngeal nerve. 394 Internally. Pharynx, Superior laryngeal nerve Tonsil, Ascending pharyngeal artery. INTERNAL CAROTID ARTERY. Externally. Internal jugular vein, Glosso-pliaryngeal, Pneumogastric, Hypoglossal nerve. Internal Carotid Artery. Behind. Pharyngeal nerve, Superior laryngeal nerve, Superior cervical ganglion, Rectus anticus major. The petrous portion is separated from the bony Avail of the carotid canal by a periosteal lining derived from the dura mater ; it is in relation with the carotid plexus, and is covered in by the Gasserian ganglion. The cavernous portion is situated in the cavernous sinus, and is in relation by its inner side with the lining membrane of the sinus, and by its outer side Avitli the sixth nerve. The cerebral portion of the artery is enclosed in a sheath of the arachnoid, and is in relation Avitli the optic nerve. At its point of dmsion it is situated in the fissure of Sylvius. Branches.—The cervical portion of the internal carotid ghres off' no branches : from the other portions are derived the folloAving :— From the Petrous portion. Tympanic. Arteriae receptaculi, Ophthalmic. From the Cavernous portion. Anterior cerebral, Middle cerebral or Sylvian, P()sterior con 1 n 1 uni cat i ng, Anterior choroid. From the Cerebral portion. The TYMPANIC is a small branch given off in the carotid canal ; it enters the tympanum and inosculates with the tympanic branch of the internal maxillary, and with the stylo-mastoid artery. The ARTERIiE RECEPTACULI anterior and posterior are two small branches given off' in the cavernous sinus and distributed to the parts contained in the sinus, to the Gasserian ganglion, and dura mater. The OPHTHALMIC ARTERY arises from the internal carotid, just as that vessel pierces the dura mater, and enters the orbit through the optic foramen, lying externally to the optic nerve. It then crosses the optic nerve to the inner Avail of the orbit; and runs along the lower border of the superior oblique muscle, to the inner angle of the eye, where it divides into two terminal branches, frontal and nasal. Branches.—The branches of the ophthalmic artery, ten in num- ber, may be arranged into two groups : first, those distributed to the orbit and surrounding parts ; and, secondly, those which supply the muscles and globe of the eve. They are :— OPHTHALMIC ARTERY. 395 Orbital Group. Lachrymal, Supraorbital, Posterior ethmoidal, Anterior ethmoidal, Palpebral, Frontal, Nasal. Ocular Group. Muscular,—anterior ciliary, Ciliary, short and long, Arteria centralis retinae. The lachrymal is the first branch of the ophthalmic artery, and is usually given off immediately before that artery enters the optic foramen. It follows the course of the lachrymal nerve, above the Fig. 254.—Distribution of the ophthalmic artery. 1. Frontal bone. 2. Crista galli. 3. Cribriform plate. 4. Lesser wing of sphenoid. 5. Upper eyelid. 6. Eyeball. 7. Lachrymal gland. 8. Optic nerve. 9. External rectus mus- cle. 10,10. Cut ends of superior rectus. 11. Origin of superior oblique. 11'. Pulley for its tendon. 11". Insertion of tendon. 12. Internal rectus, a. Internal carotid artery. 6. Ophthal- mic. c. Terminal branch dividing into (e) Nasal and (/) Frontal, d. Anterior t ethmoidal, g. Pal- pebral. h. Central artery of retina, i. Supraorbital. k. Lachrymal. V. Pal- pebral branch of lachrymal. 1. Short ciliary. to. Long ciliary, n. Posterior ethmoidal. upper border of the external rectus muscle, and is distributed to the lachrymal gland. The small branches which escape from the gland supply the conjunctiva and upper eyelid. The lachrymal artery gives off a malar branch which passes through the malar bone into the temporal fossa, and inosculates with the dee}) temporal arteries, while some of its branches become subcutaneous on the cheek, and anastomose with the transverse facial. The supraorbital artery follows the course of the frontal nerve, resting on the levator palpebrse muscle ; it passes through the supra- orbital foramen, and divides into a superficial and deep branch, which are distributed to the muscles and integument of the fore- 396 OPHTHALMIC ARTERY. head, and to the pericranium. At the supraorbital foramen it sends a branch inwards to the diploe. The ethmoidal arteries posterior and anterior pass through the internal orbital foramina, and are distributed to the falx cerebri and to the ethmoidal cells and nasal fossae. The latter accompanies the nasal nerve, and sends a branch to the frontal sinus. The branches distributed to the dura mater are called anterior meningeal. The palpebral arteries superior and inferior are given oil' from the ophthalmic, near the inner angle of the orbit; they encircle the eyelids, forming a superior and an inferior arch near the borders of the lids, between the orbicularis palpebrarum and tarsal cartilage. At the outer angle of the eyelids, the superior palpebral inosculates with the orbital branch of the temporal artery. The inferior pal- pebral artery sends a branch to the caruncula laehrymalis and lachrymal sac. The frontal artery, one of the terminal branches of the ophthal- mic, emerges from the orbit at its inner angle, and ascends along the middle of the forehead. It is distributed to the integument, muscles, and pericranium, and anastomoses with the supraorbital artery. The nasal artery, the other terminal branch of the ophthalmic, passes out of the orbit above the tendo oculi, and divides into two branches; one of which inosculates with the angular artery, while the other, dorsalis nasi, runs along the ridge of the nose, and is dis- tributed to the integument of that organ. The nasal artery sends a small branch to the lachrymal sac. The muscular branches, usually two in number, superior and inferior, supply the muscles of the orbit; and at the anterior part of the globe of the eye give off the anterior ciliary arteries, which pierce the sclerotic near its margin of connection with the cornea, and are distributed to the iris. The ciliary arteries are divisible into three groups, short, long, and anterior. The short ciliary, from ten to fifteen in number, pierce the sclerotic around the entrance to the optic nerve, and supply the choroid coat and ciliary processes. The long ciliary, two in number, pierce the sclerotic at opposite sides of the globe of the eye, and pass forwards between it and the choroid to the iris. They form an arterial circle around the circumference of the iris by inosculat- ing with each other, and from this circle branches are given off which ramify in the substance of the iris, and form a second circle around the pupil. The arteria centralis retinae pierces the optic nerve obliquely, about a quarter of an inch from the globe of the eye, and passes forwards in the centre of its cylinder to the retina, where it divides into branches, which ramify in the inner layer of that membrane. It supplies the retina and hyaloid membrane. In the foetus a small branch of this artery is seen to run through the centre of the vitreous humour to the posterior surface of the lens; it is, however, com- monlv absent in the adult. SUBCLAVIAN ARTERY. 397 The ANTERIOR CEREBRAL ARTERY passes forwards in the great longitudinal fissure between the two hemispheres of the brain ; then curves backwards along the corpus callosum to its posterior extremity. Near its commencement it gives off medullary branches which pierce the anterior perforated space to be distributed to the anterior extremity of the caudate nucleus of the corpus striatum ; at its ter- mination it gives off a branch to the corpus callosum. The two anterior cerebral arteries are connected soon after their origin by a short anastomosing trunk, the anterior communicating artery. The MIDDLE CEREBRAL ARTERY, or Sylvian'artery, larger than the preceding, passes outwards along the fissure of Sylvius, and divides into branches, which supply the anterior and middle lobes of the brain, and the island of Reil. It gives off medullary branches which pass through the substantia perforata to the back part of the caudate nucleus, the lenticular nucleus and neighbouring ] tart of the thalamus opticus. The POSTERIOR COMMUNICATING ARTERY, variable in size, sometimes double, and sometimes altogether wanting, passes back- wards and inosculates with the posterior cerebral, a branch of the basilar artery. Occasionally it is so large as to take the place of the posterior cerebral artery. The ANTERIOR CHOROID is a small branch which is given off from the internal carotid, near the origin of the posterior communi- cating artery, and passes beneath the edge of the middle lobe of the brain to (enter the descending cornu of the lateral ventricle. It is dis- tributed to the choroid plexus, and to the walls of the middle cornu. A more minute description of the arteries of the brain, their communications and distribution, will be given along with the de- scriptive anatomy of that organ in Part VI. of this work. SUBCLAVIAN ARTERY. The subclavian artery on the right side arises from the innomi- nate artery, opposite the sterno-clavicular articulation ; on the left, from the arch of the aorta. The right is consequently shorter than the left, and situated nearer the anterior wall of the chest; it is also somewhat greater in diameter, from being a branch of a branch, in place of a division from the main trunk. On both sides the artery terminates at the lower border of the tirst rib, being there continued into the axillary artery. The course of the subclavian artery is divisible, for the sake of precision and surgical observation, into three portions ; the scalenus anticus forming the means of division. The first portion of the right and left arteries differs in its course and relations in correspondence with the dissimilarity of origin above referred to. The other two portions are alike on both sides. The first portion, on the right side, ascends obliquely outwards to the inner border of the scalenus anticus. On the left side it ascends 398 perpendicularly to the inner border of that muscle. The second portion curves outwards behind the scalenus anticus ; the third por- tion passes downwards and outwards from the outer edge of the scalenus anticus to the lower border of the first rib, where it be- comes the axillary artery. SUBCLAVIAN ARTERY. Plan of the Relations of the First Portion of the Right Subclavian Artery. In Front. Skin, superficial fascia, Platysma and deep fas- cia, Clavicular part of sterno- mastoid, Sterno-thyroid, Sterno-hyoid, Iuternal jugular vein, Vertebral vein, Pneumogastric nerve, Phrenic nerve, Cardiac nerves. Behind and Beneath. Pleura, Recurrent laryngeal nerve, Sympathetic nerve, Longus colli muscle, Transverse process of 7th cervical vertebra. Right Subclavian Artery. Plan of the Relations of the First Portion of the Left Subclavian Artery. In Front. Sterno-thyroid and sterno-hyoid, Sterno-mastoid, Pleura, Internal jugular and vertebral veins, Innominate vein, Pneumogastric nerve, Cardiac nerves, Phrenic nerve. Inner Side. Left carotid artery, Trachea, (Esophagus, Thoracic duct. Left Subclavian Artery. Outer Side. Pleura. Behind. (Esophagus, Thoracic duct, Inferior cervical ganglion, Longus colli, Vertebral column. Plan of the Relations of the Second Portion of the Subclavian Artery. In Front. Skin and superficial fascia, Platysma and deep fascia, Sterno- mastoid, Scalenus anticus. PLATE 22. DEEP DISSECTION OF HEAD AND NECK A. Right common carotid (cut). B. Right subclavian. C. Trachea. D. Thyroid axis. E. Vagus nerve, crossing subcla- vian artery. F. Subclavian artery, third part. G. Posterior scapular artery, aris- ing from third part of sub clavian. H. Supra-scapular artery. I. Superficialis colli artery. K. Posterior belly of omo-hyoid. L. Median nerve, branch of brach- ial plexus. M. Brachial plexus. N. Scalenus auticus, with phrenic nerve lying on it. O. Cervical plexus. P. Upper part of internal jugular vein. Q. Upper part of internal carotid artery. R. Superior cervical ganglion of sympathetic. S. Upper part of vagus nerve. T. Superior thyroid artery. V. Hyo-glossus muscle covering lingual artery. W. Sublingual gland. X. Genio-hyoid muscle. Y. Mylo - hyoid muscle (turned down). Z. Thyroid cartilage. 1. Stcrno-hyoid muscle. 2. Omo-hyoid muscle. 3. Inferior constrictor of pharynx. 4. Cricoid cartilage. 5. Crico-thyroid muscle. 6. Thyroid body. 7. Inferior thyroid artery. 8. Sternal origin of sterno-mas- toid. 9. Clavicular origin of sterno- mastoid. 10. Clavicle. 11. Trapezius. 12. Scalenus medius. 13. Rectus capitis auticus major. 14. Stylo-hyoid muscle (turned back). 15. Temporal artery. 16. Internal maxillary artery. 17. Inferior dental nerve. 18. Lingual branch of 5th nerve. 19. External pterygoid muscle. 20. Internal pterygoid muscle. 21. Temporal muscle (cut). 22. Zygomatic arch. 23. Buccinator. 24. Masseter. 25. Middle constrictor of pharynx. PLATE 22. SUBCLAVIAN ARTERY. 399 Above. Brachial plexus. Subclavian Artery. Second Portion. Below. Pleura. Behind. Scalenus medius, First dorsal nerve. The third portion of the arterv is situated in the subclavian tri- angle, and is more superficial tha he 1 st Plan of the Relations of the Third Portion of the Subclavian Artery. Above. Brachial plexus, Omo-hyoid. In Front. Integument and superficial fascia, Platysma and deep fascia, External jugular vein, Supraclavicular nerves, Suprascapular vessels, Clavicle, Subclavius. Subclavian Artery. Portion. Behind. Scalenus medius Below. First rib, Subclavian vein. Branches.—The branches of the subclavian artery are four, and sometimes five, in number. Three are given off by the first portion of the artery ; one, the superior intercostal, by the second portion; when a fifth artery exists, it arises from the third portion, and is the posterior scapular. So frequent is the occurrence of this variation, that many anatomists consider it to be the normal condition. In a tabular form the branches are as follows :— Vertebral, Internal mammary, Inferior thyroid, Suprascapular, or transversalis humeri, Transversalis colli. Thyroid axis, Superior intercostal,—Deep cervical. The VERTEBRAL ARTERY, the first and largest of the branches of the subclavian artery, arises from the posterior aspect of that trunk ; it ascends through the foramina in the transverse processes of all the cervical vertebrae, excepting the last ; then winds back- wards around the articulating process of the atlas; and, piercing 400 the dura mater, enters the skull through the foramen magnum. The two arteries unite at the lower border of the pons Varolii, to form the basilar artery. At its origin the artery is behind the in- ternal jugular vein, and as it ascends comes to be placed between the scalenus anticus and longus colli muscles; on the left side, it is crossed by the thoracic duct. In the foramina of the transverse pro- cesses of the vertebrae the artery lies in front of the cervical nerves, and has the vertebral vein in front of it. The sub-occipital nerve passes out beneath it where it lies on the groove of the atlas. As it enters the cranium the vertebral artery is placed between the hypo- glossal nerve and the anterior root of the sub-occipital nerve, beneath the first process of the ligamentum denticulatum ; it next winds round the medulla and lies between it and the basilar portion of the occipital bone. If the two arteries differ in size, the left is generally the larger. The basilar artery formed by the union of the two vertebrals is so named from its position at the base of the brain ; it runs forward in the groove on the midline of the pons Varolii, and at the anterior border of the pons divides into four terminal branches, two to each side. Branches.—The branches of the vertebral artery are the fol- lowing :— BRANCHES OF SUBCLAVIAN ARTERY. Lateral spinal, Muscular, or Sub-occipital, Posterior meningeal, Anterior spinal, Posterior spinal, Posterior inferior cerebellar. The lateral spinal branches enter the intervertebral foramina, and taking the course of the roots of the spinal nerves, reach the spinal canals, where each divides into two branches, one to be distri- buted to the spinal cord, anastomosing with the other spinal arteries, and the second branch passing to the body of the vertebra. The muscular or sub-occipital branches are distributed to the deep muscles of the neck, as the vertebral artery curves round the articular process of the atlas ; they anastomose with the deep cervical and occipital arteries. The posterior meningeal are one or two small branches which enter the cranium through the foramen magnum, to be distributed to the dura mater of the cerebellar fossae, and to the falx cerebelli. The anterior spinal is a small branch which unites with its fellow of the opposite side on the front of the medulla oblongata. The artery formed by the union of these two vessels descends along the anterior aspect of the spinal cord, to which it distributes branches ; they anastomose with the other spinal arteries. The posterior spinal winds around the medulla oblongata to the posterior aspect of the cord, and descends on each side to the cauda equina. It communicates very freely with the spinal branches of the intercostal and lumbar arteries, and near its origin sends a branch upwards to the fourth ventricle. The posterior inferior cerebellar arteries wind around the BASILAR ARTERY. 401 upper part of the medulla oblongata to the under surface of the cerebellum, to which they are distributed. They pass between the filaments of origin of the hypoglossal nerve in their course, and anastomose with the superior cerebellar arteries. The branches of the basilar artery are :— Transverse, Superior cerebellar, Posterior cerebral. The transverse branches of the basilar artery supply the pons Yarolii and adjacent parts of the brain. One of these branches, Fig. 255—Circle of Willis. The arteries being sym- metrical have refer- ences on one side only. 1. Vertebral arteries. 2. Anterior spinal branches uniting to form a single vessel. 3. Posterior spinal ar- tery. 4. Posterior men- ingeal. 5. Posterior in- ferior cerebellar. 6. Basilar artery giving off transverse branches. 7. Superior cerebellar artery. 8. Posterior cerebral. 9. Posterior communicating branch of the internal carotid. 10. Internal carotid ar- tery, showing its curves within the skull, n. Ophthalmic artery di- vided across. 12. Middle cerebral artery. 13. Anterior cerebral ar- teries, connected by, 14, Anterior commu- nicating artery. 15. Medullary branches of anterior cerebral. 16. Medullary branches of middle cerebral. 17. Medullary branches of posterior cerebral. larger than the re&t, receives the name of anterior inferior cere- bellar artery ; it passes along the crus cerehelli to he distributed to the anterior border of the cerebellum, and anastomoses with the inferior cerebellar of the vertebral. Another small branch of the basilar is known as the auditory artery ; it accompanies the facial and auditory nerves into the meatus auditorius internus, and is distributed to the internal ear. The superior cerebellar arteries, two of the terminal branches of the basilar, wind around the crus cerebri on each side, lying in relation with the fourth nerve, and are distributed to the upper surface of the cerebellum, inosculating with the inferior cerebellar. 402 BRANCHES OF THE SUBCLAVIAN ARTERY. The posterior cerebral arteries, the other two terminal branches of the basilar, wind around the crus cerebri at each side, and are distributed to the posterior lobes of the cerebrum. T hey are sepa- rated from the superior cerebellar arteries near their origin, by the third pair of nerves, and are in close relation with the fourth pair in their course around the crura cerebri. Anteriorly, near their origin, they give off a tuft of small medullary vessels which enter the locus perforatus to supply the optic thalamus and corpora quad- rigeinina. They receive the posterior communicating arteries from the internal carotid, and send a branch called posterior choroid, to the velum interpositum and choroid plexus. The communications established between the anterior cerebral arteries in front, and the internal carotids and posterior cerebral arteries behind, by the communicating arteries, constitute the circle of Willis. This remarkable vascular communication at the base of the brain is formed by the anterior communicating branch, anterior cerebrals, and internal carotid arteries in front, and by the posterior communicating, posterior cerebrals, and basilar artery behind. A more full description of the arteries of the brain will be found in Part VI. The INTERNAL MAMMARY ARTERY arises from the under side of the subclavian, and passes down behind the subclavian vein to the cartilage of the first rib. It then descends by the side of the sternum, resting on the cartilages of the ribs, to the level of the sixth intercostal space, where it divides into two terminal branches, superior epigastric and musculo-phrenic. At its origin the artery is covered by the internal jugular and subclavian veins, and as it enters the chest it is crossed by the phrenic nerve ; it then gets under cover of the pleura, and lower down lies between the triangularis sterni and internal intercostal muscles. The branches of the internal mammary are— Comes nervi phrenici, Mediastinal, Pericardiac, Thymic, Anterior intercostal Perforating, Musculo-pnrenic, Superior epigastric. The conies nervi phrenici, a long and slender branch given oil by the artery as it enters the chest, descends with the phrenic nerve between the pleura and pericardium to the diaphragm, to which it is distributed, inosculating with the musculo-phrenic and abdominal phrenic arteries. The mediastinal, pericardiac, and thymic branches are small vessels distributed to the anterior mediastinum, pericardium, and thymus gland. Some sternal branches are sent to supply the ster- num and triangularis sterni muscle. The anterior intercostals supply the intercostal muscles of the front of the chest, and inosculate with the aortic intercostals ; to each space there are two arteries which either arise separately or INTERNAL MAMMARY ARTERY. 403 by common trunks and run along the borders of the rib. Besides supplying the intercostal muscles, they send branches to the pectoral muscles and mammary gland. The perforating arteries pass forward to the front of the chest through the first six intercostal spaces ; they then turn outwards, and after giving some branches to the front of the sternum, are dis- tributed to the pectoral muscles and mammary gland. Those intended for the mammary gland are of larger size than the rest. The musculo-phrenic artery, proceeding from the internal mam- mary at the interspace between the sixth and seventh ribs, passes downwards and outwards over the cartilages of the false ribs to the last intercostal space. It pierces the diaphragm at the attachment of that muscle to the eighth rib, and sends branches to its muscular structure, and others to the intercostal spaces of the false ribs which form the anterior intercostal arteries of those spaces, and are dis- tributed in the same way as those above described. The superior epigastric artery descends in the sheath of the rectus muscle, and gives off branches which are distributed to the muscles of the abdominal wall. It anastomoses with the deep epigastric, a branch of the external iliac. The mammary arteries are remarkable for the number of their inosculations, and for the distant parts of the arterial system which they serve to connect. They anastomose with each other, and their inosculations, with the thoracic aorta, encircle the thorax. On the parietes of this cavity their branches connect the axillary and sub- clavian arteries : on the diaphragm they form a link in the chain of inosculations between the subclavian artery and abdominal aorta ; and in the parietes of the abdomen they form an anastomosis most remarkable for the distance between those vessels which it serves to connect—namely, the arteries of the superior and inferior extremities. The THYROID AXIS is a short trunk which arises from the front of the subclavian close to the inner border of the anterior scalenus, and divides almost immediately into three branches, inferior thyroid, supra-scapular, and transversalis colli. The INFERIOR THYROID ARTERY ascends obliquely in a ser- pentine course behind the sheath of the carotid vessels, and in front of the longus colli, to the inferior and posterior part of the thyroid gland, to which it is distributed. It is in relation with the middle cervical ganglion of the sympathetic, which lies in front of it. It gives off the following branches :— Inferior laryngeal, Tracheal, (Esophageal. Ascending cervical, Glandular, Muscular. The inferior laryngeal accompanies the recurrent laryngeal nerve to the larynx and is distributed to the muscles and mucous mem- brane. BRANCHES OF THE SUBCLAVIAN ARTERY. Ihe tracheal and oesophageal branches ramify on the trachea and oesophagus. The ascending cervical, a branch of the inferior thyroid, ascends upon the anterior tubercles of the transverse processes of the cervical vertebrae, lying in the groove between the scalenus anticus and rectus anticus major. It is distributed to the deep muscles and glands of the neck, and sends branches through the intervertebral foramina to supply the spinal cord and its membranes. The glandular branches pass to the thyroid body and anastomose with the branches of the superior thyroid artery. The muscular branches supply the scalenus anticus, longus colli, and depressor muscles of the hvoid bone. The SUPRA-SCAPULAR or TRANSVERSALIS HUMERI ARTERY passes obliquely outwards behind the clavicle, and over the ligament of the supra-scapular notch, to the supra-spinous fossa. It crosses in its course the scalenus anticus mus- cle, phrenic nerve, and subclavian artery; is distributed to the mus- cles of the dorsum of the scapula, and inosculates with the posterior scapular, and beneath the acromion process with the dorsal branch of the subscapular artery. At the supra-scapular notch it sends a large branch outwards, which pierces the trapezius muscle, and becomes cutaneous at the tip of the shoulder {acromial). It gives a number of small branches to the capsule of the shoulder-joint. The supra- scapular artery sometimes arises directly from the subclavian. The TRANSVERSALIS COLLI ARTERY passes transversely across the subclavian triangle at the root of the neck, to the anterior border of the levator anguli scapula*, where it divides into two terminal branches, the superficial cervical and posterior scapular. In its course it lies above the supra-scapular artery, and crosses the scaleni muscles and brachial plexus of nerves, often passing between the latter. At its bifurcation it is covered in by the edge of the trapezius. The superficial cervical artery, its ascending branch, passes upwards under cover of the anterior border of the trapezius, and is distributed to the superficial muscles of the neck and deep cervical glands. The posterior scapular artery, the proper continuation of the transversalis colli, passes backwards to the superior angle of tire 404 Fig. 256.—View of the branches of the right subclavian artery. 1. Innomi- nate artery. 2. Common carotid. 3. Subclavian. 4. Internal mammary. 5. Vertebral. 6. Thyroid axis. 7. Inferior thyroid. 8. Ascending cer- vical. 9. Transversalis colli. 10. Supra-scapular. n. Common trunk dividing into superior intercostal and deep cervical. scapula, and then descends along the posterior border of that bone to its inferior angle, where it inosculates with the subscapular artery. In its course it lies under cover of the levator anguli scapulae and rhomboidei muscles, distributes branches to them and neighbouring muscles, and inosculates with the arteries of the scapula and branches of the intercostal arteries. The superficial cervical and posterior scapular artery sometimes arise separately, the former from the thyroid axis, the latter from the third portion of the subclavian. By means of its numerous inosculations the transversalis colli artery maintains an important anastomotic communication between the branches of the external carotid, subclavian, and axillary arteries. The SUPERIOR INTERCOSTAL ARTERY arises from the upper and back part of the subclavian artery behind the scalenus anticus, and, descending in front of the necks of the first two ribs, sends intercostal branches to the first two intercostal spaces, and dorsal branches to the muscles and integument of the back. The artery lies behind the pleura, to the outer side of the sympathetic nerve, and in the second intercostal space inosculates with the first aortie intercostal. It gives off the deep cervical artery. The deep cervical (cervicalis profunda) artery arises by a common trunk with the preceding, or, more properly, is a branch of the superior intercostal, corresponding with the posterior branch of the other intercostal arteries. It passes backwards between the transverse processes of the seventh cervical and first dorsal vertebra, and ascends the back part of the neck, between the complexus and semispinalis colli muscle. It inosculates with the princeps cervicis of the occipital artery, and with branches of the vertebral. Varieties of the Subclavian Arteries.—Varieties in these arteries are rare ; that which most frequently occurs is the origin of the right subclavian from the left extremity of the arch of the aorta, below the left subclavian artery. The vessel, in this case, curves behind the oesophagus and right carotid artery, and some- times between the oesophagus and trachea, to the upper border of the first rib on the right side of the chest, where it assumes its ordinary course. Occasionally the left carotid and subclavian arise by a common trunk, as well as those on the right, so that there are two innominate arteries, and in rare cases the four branches all arise separately from the aorta, the right subclavian, however, retaining its normal position. Varieties in the branches of the subclavian are not unfrequent; the most interesting is the origin of the left ver- tebral from the arch of the aorta. SUPERIOR INTERCOSTAL ARTERY. 405 AXILLARY ARTERY. Tlie axillary artery passes outwards and downwards with a gentle curve through the axillary space from the lower border of the first rib to the lower border of the tendons of the latissimus dorsi and teres major, where it becomes the brachial. For convenience of 406 AXILLARY ARTERY. description it is divided into three parts : the first part extends from the lower border of the first rib to the upper border of the pectoralis minor ; the second part lies behind the pectoralis minor, and extends from the upper to the lower border of that muscle ; the third part extends from the lower border of the pectoralis minor to the lower border of the tendons of the latissimus dorsi and teres major. Plan of the Relations of the First Part of the Axillary Artery. In Front. Pectoralis major, Costo-coracoid membrane, Acromial thoracic and cephalic veins, Subclavius muscle. Outer Side. Brachial plexus. Axillary Artery First Part. Inner Side. Axillary vein. Behind. First intercostal space, Serratus magnus, Posterior thoracic nerve. Plan of the Relations of the Second Part of the Axillary Artery. In Front. Pectoralis major, Pectoralis minor. Outer Side. Outer cord of plexus. Axillary Artery. Second Part. Inner Side. Inner cord of plexus, Axillary vein. Behind. Subscapularis, Posterior cord of plexus. Plan of the Relations of the Third Part of the Axillary Artery. In Front. Integument and fascia, Pectoralis major, Inner head of median nerve Outer Side. Outer head of median, External cutaneous, Coraco-brachialis. Inner Side. Inner head of median, Internal cutaneous, Lesser internal cutaneous, Ulnar, Axillary vein. Axillary Artery. Third Part. Behind. Subscapularis, Musculo-spiral nerve, Circumflex nerve, Tendons of latissimus and teres major. AXILLARY ARTERY. 407 Branches.—The branches of the axillary artery are seven in number :— From first vart J1 1 • Superior thoracic, Acromial thoracic. o , , From second fart, Inferior or long thoracic, Alar thoracic. From third part. ' Subscapular, Anterior circumflex, Posterior circumflex. The superior thoracic and acromial thoracic are found in the triangular space above the pectoralis minor; the inferior thoracic Fig. 257.—Axillary and brachial artery, with their branches. 1. Deltoid. 2. Bi- ceps. 3. Tendinous process given off from the tendon of the biceps to the deep fascia of the forearm ; this process separates the median basilic vein from the brachial artery. 4. Outer border of the brachialis anticus. 5. Supinator longus. 6. Coraco-brachialis. 7. Middle portion of the triceps. 8. Its inner head. 9. Axillary artery. 10. Brachial artery ; —a dark bar marks the limit between these two vessels. 11. Acromial thoracic artery dividing into its three branches ; the figure rests on the coracoid process. 12. The superior and long thoracic ar- teries. 13. Serratus magnus muscle. 14. Subscapular artery. The posterior circumflex and alar thoracic branches are seen in the figure between the in- ferior thoracic and subscapular. The auterior circumflex is observed between the two heads of the biceps, crossing the neck of the humerus. 15. Superior pro- funda. 16. Inferior profunda. 17. Anas- tomotica magna inosculating interiorly with the anterior ulnar recurrent. 18. Termination of the superior profunda, inosculating with the radial recurrent in the interspace between the brachialis anticus and supinator longus. and alar thoracic below the pectoralis minor; and the three re- maining branches below the lower border of the subscapularis. The superior thoracic (short thoracic), the highest of the branches of the axillary, and sometimes derived from the next, passes inwards to the chest in front of the pectoralis minor muscle, and is distri- 408 AXILLARY ARTERY. buted to the pectoral muscles and walls of the chest. It anastomoses with the intercostal and mammary arteries. The acromial thoracic (thoracic axis) is a short trunk which proceeds from the axillary in the space above the pectoralis minor muscle, and divides into four sets of branches : which are distributed to the pectoral muscles, serratus magnus, and mammary gland ; acromial, which pass outwards to the acromion, and inoscu- late with branches of the supra-scapular artery; descending (thoracica humeraria), a single branch, which follows the interspace between the deltoid and pectoralis major muscle, and is in relation with the cephalic vein ; and one or more clavicular branches which pass to the subclavius muscle and supply it. The inferior or long thoracic (external mammary) descends along the lower border of the pectoralis minor to the .side of the chest. It is distributed to the pectoralis major and minor, serratus magnus, and mammary gland; inosculating with the superior thoracic, intercostal, and mammary arteries. The alar thoracic is a small branch distributed to the plexus of nerves and glands in the axilla. It is frequently wanting, its place being supplied by a branch derived from one of the other thoracic branches. The subscapular artery, the largest of the branches of the axillary, runs along the lower border of the subscapular muscle, to the inferior angle of the scapula, -where it inosculates with the posterior scapular, a branch from the subclavian. It supplies the muscles of the under surface and inferior border of the scapula, and the side of the chest. At about an inch and a half from the axillary, it gives off a large branch, the dorsalis scapulae, which passes back- wards through the triangular space bounded by the teres minor, teres major, and scapular head of the triceps, and beneath the infra-spinatus muscle to the dorsum of the scapula, where it is dis- tributed, inosculating with the supra-scapular and posterior scapular arteries. The circumflex arteries wind around the neck of the humerus. The anterior, very small, passes beneath the coraco-brachialis and short head of the biceps, and sends a branch upwards along the bicipital groove to supply the shoulder-joint; it then passes be- neath the deltoid, and distributes branches to that muscle, which anastomose with the posterior circumflex and acromial thoracic arteries. The posterior circumflex, of larger size, passes backwards through the quadrangular space bounded by the teres minor and major, the scapular head of the triceps, and humerus, and is distributed to the deltoid muscle and shoulder-joint; it anastomoses with the anterior circumflex, subscapular, acromial thoracic, and superior profunda arteries. Sometimes this artery is a branch of the superior profunda of the brachial ; it then ascends behind the tendon of the teres major, and is distributed to the deltoid without passing through the quadrangular space. BRACHIAL ARTERY. Varieties of the Axillary Artery.—The most frequent pecu- liarity of this kind is the division of the vessel into two trunks of equal size : a muscular trunk, which gives off some of the ordinary axillary branches and supplies the upper arm, and a continued trunk which represents the brachial artery. The next most frequent variety is the high division of the radial which passes down the arm by the side of the brachial artery, and at the elbow takes its usual position, and is continued to its ordinary distribution in the hand. Sometimes there is a high division of the ulnar, that artery being given off in the axilla; at the elbow it passes superficially to the muscles attached to the internal condyle, and may in life be seen and felt pulsating immediately beneath the deep fascia. 409 BRACHIAL ARTERY, The brachial artery passes down the inner side of the arm, from the lower border of the tendons of the latissimus dorsi and teres major, to a point opposite the neck of the radius, where it divides into the radial and ulnar artery. Plan of the Relations of the Brachial Artery. In Front. Integument and fasciae, Median nerve, Median-basilic vein, Bicipital fascia. Inner Side. Internal cutaneous nerve, Ulnar nerve, Median nerve (below), Basilic vein. Brachial Artery. Outer Side. Median nerve (above), Coraco-brachialis, Biceps. Behind. Triceps, Musculo-spiral nerve, Superior profunda artery, Coraco-brachialis, Brachialis anticus. The branches of the brachial artery are the— Superior profunda, Inferior profunda, Anastomotica magna, Muscular and nutrient. The superior profunda arises opposite the lower border of the tendon of the latissimus dorsi, and winds around the humerus in the musculo-spiral groove, between the triceps and the bone, to the space between the brachialis anticus and supinator longus, where it inosculates with the radial recurrent artery. It accompanies the musculo-spiral nerve. In its course it gives off the posterity)' articular artery, which descends to the elbow-joint, and a more superficial branch, which descends by the side of the external intermuscular 410 BRACHIAL ARTERY. septum and inosculates with the posterior interosseous recurrent artery. The inferior muscular branches of the superior profunda inosculate with the inferior profunda, anastomotica magna, and ulnar recurrent. This artery supplies the coraco-brachialis, deltoid, triceps, brachialis anticus, and the muscles attached to the external condyle and condylar ridge. The inferior profunda arises from about the middle of the brachial artery, and descends with the ulnar nerve to the space between the inner condyle and olecranon, where it inosculates with the posterior ulnar recurrent. It also gives a branch to the front of the internal condyle, which anastomoses with the anterior ulnar recurrent and anastomotica magna. In its course it pierces the in- ternal intermuscular septum from before backwards. The anastomotica magna is given off nearly at right angles from the brachial, at about two inches above the joint. It passes directly inwards upon the brachialis anticus muscle, pierces the internal intermuscular septum, and winds around the humerus to inosculate with the superior profunda. On the brachialis anticus it divides into two branches, which inosculate with the anterior and posterior ulnar recurrent arteries, and with the inferior profunda. The muscular branches are distributed to the muscles in the course of the artery, namely, coraco-brachialis, biceps, deltoid, brachialis anticus, and triceps. The nutrient branch is given off at about the middle of the arm, and passes into the medullary foramen near the insertion of the coraco-brachialis muscle. Varieties of the Brachial Artery.—The most frequent pecu- liarity in the distribution of branches from this artery is the high division of the radial, which arises generally from about the upper third of the brachial artery, and descends to its normal position at the bend of the elbow. The ulnar artery sometimes arises from the brachial at about two inches above the elbow, and pursues either a superficial or deep course to the wrist; and in some instances the interosseous artery arises from the brachial a little above the bend of the elbow. The two profunda arteries occasionally arise by a common trunk, or there may be two superior profunda?. Fre- quently a small branch is given off close to the origin of the superior profunda, or is derived from that vessel; it descends over the median nerve, supplies the biceps, and unites with the radial, or (less frequently) with the ulnar. It is called vas aberrans, and sometimes replaces the brachial itself. At the bend of the elbow the brachial artery terminates by dividing into radial and ulnar ; it here lies deeply in a triangular space which is sometimes called the antecubital fossa. This space is bounded above by an imaginary line drawn across the arm about two inches above the condyles, on the inner side by the pronator radii BEND OF THE ELBOW. RADIAL ARTERY. teres, and on the outer side by the supinator longus ; its apex is situated below, at the point where the pronator teres and supinator longus come in contact. The floor is formed bv the lower part of the brachialis anticus, and the oblique fibres of the supinator brevis. The contents of the space, enumerated from within outwards, are the median nerve, brachial artery, and the tendon of the biceps. By displacing the supinator longus a little to the outer side, the musculo-spiral nerve and superior profunda artery can be brought into view ; the former here divides into radial and posterior inter- osseous nerves, and the hitter anastomoses with the radial recurrent artery, but neither the nerve nor the artery are, strictly speaking, contents of the triangle. The radial artery, one of the divisions of the brachial, appears, from its direction, to be the continuation of that trunk, it runs along the radial side of the forearm, from the bend of the elbow to the wrist; it then turns backwards around the base of the thumb, beneath its extensor tendons, and passes between the two heads of the first dorsal interosseous muscle, into the palm of the hand. It next crosses the metacarpal bones to the ulnar side of the hand, forming the deep palmar arch, and terminates by inosculating with the deep branch of the ulnar artery. Relations.—In the upper half of its course, the radial artery is situated between the supinator longus muscle, by which it is slightly overlapped, and the pronator radii teres ; in the lower half between the tendons of the supinator longus and flexor carpi radialis. RADIAL ARTERY. Plan of the Relations of the Radial Artery in the Forearm. In Front. Integument and fasciae, Supinator longus. Outer Side. Supinator longus, Radial nerve (middle third). Inner Side. Pronator radii teres, Flexor carpi radialis, Radial Artery. Behind. Tendon of biceps, Supinator brevis, Pronator radii teres, Flexor sublimis digitorum Flexor longus pollicis, Pronator quadratus, Radius. At the wrist it winds round the outer side of the carpus, and lies in succession on the external lateral ligament, scaphoid, and trapezium, and is covered by the extensor tendons of the thumb, subcutaneous veins, and some twigs of the radial nerve. 412 RADIAL ARTERY. In the hand it rests on the bases of the metacarpal bones and the interossei muscles, and is covered by the flexor tendons, flexor longus pollicis, lumbricales, opponens minimi digiti, flexor brevis minimi digiti, and flexor brevis pollicis. It is accompanied by the deep ulnar nerve. The branches of the radial artery may be arranged into three groups, corresponding with the three regions—forearm, wrist, and hand : they are— • Radial recurrent, Forearm. Muscular. volse, Anterior carpal, Posterior carpal, Wrist. Metacarpal, Dorsales pollicis, Dorsalis indicis. Princeps pollicis, Radialis indicis, Hand. Interosseous, Perforating, Recurrent. The radial recurrent branch is given off immediately below the elbow; it ascends in the space between the supinator longus and brachialis anticus, sends branches to the muscles arising from the external condyle, and inosculates with the terminal branches of the superior profunda. The muscular branches are distributed to the muscles of the radial border of the forearm. The superficialis volse is given off by the radial artery while at the wrist. It passes between the fibres of the abductor pollicis muscle, and inosculates with the termination of the ulnar artery, completing the superficial palmar arch. This artery is variable in size, being sometimes as large as the continuation of the radial, at other times a mere muscular twig, or entirely wanting ; when of large size it supplies the palmar side of the thumb and radial side of the index finger. The anterior carpal passes inwards along the lower border of the pronator quadratus, and forms an arch by inosculating with the anterior carpal branch of the ulnar artery. From this arch twigs are given off to supply the wrist-joint. The posterior carpal arises from the radial artery beneath the extensor tendons of the thumb ; it crosses the carpus transversely, and inosculates with the posterior carpal branch of the ulnar artery. Superiorly it inosculates with the termination of the anterior inter- osseous artery ; interiorly it gives off dorsal interosseous branches, which anastomose with the perforating branches of the deep palmar arch, and run forward upon the dorsal interosseous muscles of the third and fourth metacarpal spaces. The metacarpal or first dorsal interosseous branch often arises in common with the posterior carpal ; it runs forward to the meta- RADIAL ARTERY. carpal space between the index and middle finger. At the cleft of the fingers it inosculates witli the palmar digital artery, and gives off dorsal collateral branches. It is joined by a perforating branch from the deep palmar arch which reaches it by passing between the heads of the second dor- sal interosseous muscle. The dorsales polli- cis are two small branches which run along the sides of the dorsal aspect of the thumb. The dorsalis indicis is a very small branch wThich runs along the radial border of the metacarpal bone and phalanges of the in- dex finger. The princeps polli- cis (arteria inagna pol- licis), the great artery of the thumb, passes along the metacarpal bone of the thumb, between the first dor- sal interosseous (ab- ductor indicis) and flexor brevis pollicis to the base of the first pha- lanx ; and, between the two heads of the latter muscle, in the groove of the tendon of the flexor longus, it divides into two collateral branches for the palmar borders of the thumb. The radialis indi- cis, the digital branch of the radial side of the index finger, is directed inwards, between the first dorsal interosseous muscle and flexor brevis and adductor pollicis, to the side of the finger, along which it runs, forming its radial collateral artery, and anastomosing with the digital branch from the superficial arch. Near its origin it gives off a small branch (more frequently a direct branch of the radial), which inosculates with the superficial palmar arch, and often also effects a communication with the artery of the thumb. The palmar interosseous, three or four in number, are branches Fig. 258.—Arteries of the forearm. I. Biceps. 2. Inner condyle of humer- us with the hu- meral origin of the pronator radii teres and flexor carpi radialis di- vided across. 3. Deep portion of pronator radii ter- es. 4. Supinator longus. 5. Flexor longus pollicis. 6. Pronator quadra- tus. 7. Flexor pro- fundus digit orum. 8. Flexor carpi ul- naris. 9. Annular ligament with the tendons passing ben eath it into the palm of the hand ; the figure is placed on the tendon of the palmaris lon- gus, divided close to its insertion. 10. Brachial artery, II. Anastomotica magna. 12. Radial artery. 13. Radial recurrent. 14. Su- perficialis vote. 15. Ulnar artery. 16. Superficial pal- mar arch. 17. Princeps pollicis and radialis indi- cis. 18. Posterior ulnar recurrent. 19. Anterior inter- osseous. 20. Poste- rior interosseous, passing through the interosseous membrane. ULNAR ARTERY. 414 of the deep palmar arch ; they pass forward upon the interosseous muscles, and inosculate with the digital branches of the superficial arch, opposite the heads of the metacarpal bones. The perforating branches, three in number, pass directly back- wards between the heads of the dorsal interosseous muscles, and inosculate with the dorsal interosseous arteries. The recurrent branches of the deep palmar arch pass upwards in front of the wrist-joint, and inosculate with the arterial arch formed by the anterior carpal arteries. ULNAR ARTERY. The ulnar artery, the other and larger division of the brachial, crosses the forearm obliquely, to the commencement of its middle third ; it then runs down the ulnar side of the forearm to the wrist, crosses the annular ligament into the hand, and forms the superficial palmar arch which terminates by inosculating with the superficialis volae. Relations.—In the upper or oblique portion of its course it lies upon the brachialis anticus and flexor profundus digitorum, and is covered in by the superficial layer of muscles of the forearm and median nerve. In the second part of its course, it is placed upon the flexor profundus and pronator quadratus, lying between the flexor carpi ulnaris and flexor sublimis digitorum. While crossing the annular ligament it is protected from injury by a strong tendinous arch, thrown over it from the pisiform bone ; and in the palm it rests on the origin of the muscles of the little finger, and the tendons of the flexor sublimis, being covered in by the palmaris brevis muscle and palmar fascia. It is accompanied in its course by the venae comites, and is in relation with the ulnar nerve for the lower two- thirds of its extent, the nerve lying to its ulnar side. Plan of the Relations of the Ulnar Artery. In Front. Superficial and deep fascia, Superficial layer of flexor muscles, Median nerve. In the Hand. Tendinous arch from the pisiform bone, Palmaris brevis muscle, Palmar fascia. Inner Side. Flexor carpi ulnaris, Ulnar nerve (lower two- thirds). Outer Side. Flexor sublimis digi- torum. Ulnar Artery. Behind. Brachialis anticus, Flexor profundus digitorum, Pronator quadratus. Figs. 1 and 2. A. Radial artery. B. Median nerve. C. Ulnar artery. D. Annular ligament. E. Ulnar nerve. F. Insertion of flexor carpi ulnaris. •fUPisiform bone. H. Abductor minimi digiti. I. Tendon of flexor carpi radialis. K. Abductor pollicis. L. Flexor brevis minimi digiti. M. Flexor brevis pollicis. O. Lumbricales. P. Flexor tendons. Q. Tendon of flexor longus pollicis. R. Supinator longus. S. Flexor sublimis digitorum. T. Flexor carpi ulnaris. PALM AND BACK OF THE HAND. PLATE 28. Fig. 3. A. Extensor communis digitorum. B. Posterior annular ligament. C. Radial nerve. D. Ulnar nerve. E. Radial artery. F. Extensor carpi radialis brevior. G. Extensor carpi radialis longior. H. Extensor secundiinternodiipollicis. I. Extensor primi internodii pollicis. K. Extensor minimi digiti. PLATE 23, % 3 Fy.2 Fr31 ULNAR ARTERY. 415 Annular ligament, Origin of muscles of little finger, Tendons of the flexor sublimis digitorum, Divisions of the median and ulnar nerves. In the Hand. The branches of the ulnar artery may be arranged, like those of the radial, into three groups :— Anterior ulnar recurrent, Posterior ulnar recurrent, Forearm, Interosseous, Anterior interosseous, Posterior interosseous, Muscular. Anterior carpal, Posterior carpal, Metacarpal. Wrist, Hand, Communicating, Digital. The anterior ulnar recurrent, arising immediately below the elbow, ascends in front of the joint between the pronator radii teres and brachialis anticus; it distributes branches to the adjacent muscles, and inosculates with the anastomotica inagna and infe- rior profunda. The two recurrent arteries frequently arise by a common trunk. The posterior ulnar recurrent, larger than the preceding, arises immediately below the elbow-joint, and passes backwards, beneath the origin of the superficial layer of muscles ; it then ascends be- tween the two heads of the flexor carpi ulnaris, lying beneath the ulnar nerve, and inosculates with the inferior profunda, anastomotica magna, and interosseous recurrent. The INTEROSSEOUS ARTERY is a short trunk which arises from the ulnar, opposite the bicipital tuberosity of the radius, and passes backwards to the interosseous membrane, where it divides into the anterior and posterior interosseous artery. The anterior interosseous passes down the forearm upon the interosseous membrane, in company with the anterior interosseous nerve, between the flexor-profundus digitorum and flexor longus pollicis, and behind the pronator quadratus ; it then passes through an opening in the interosseous membrane to the back of the wrist, where it inosculates with the posterior carpal branches of the radial and ulnar. The anterior interosseous artery gives off several mus- cular branches ; nutrient branches to the radius and ulna; a com- panion branch to the median nerve (arteria comes nervi mediani); and at the upper border of the pronator quadratus, a small branch, which descends behind that muscle to inosculate with the anterior carpal arteries. The median artery is sometimes of large size, and occasionally assists in forming the superficial palmar arch. The posterior interosseous artery passes backwards through an opening between the upper part of the interosseous membrane and 416 ULNAR ARTERY. the oblique ligament, and descends between the superficial and deep layer of muscles of the forearm to the back of the wrist, where it inosculates with the anterior interosseous and posterior carpal branches of the radial and ulnar. At its upper part it gives off a recurrent branch, posterior interosseous recurrent, which re- turns upon the elbow between the anconeus, extensor carpi ulnaris, and supinator brevis, and anastomoses with the posterior terminal branches of the superior profunda. The muscular branches of the ulnar artery are distributed to the muscles of the ulnar border of the forearm. The anterior carpal, a branch of small size, passes outwards upon the front of the wrist-joint, and contributes to form the anterior carpal arch by inosculating with the anterior carpal branch of the radial artery. The posterior carpal, larger than the preceding, passes beneath the tendon of the flexor carpi ulnaris muscle to the back of the wrist-joint, where it inosculates with the posterior carpal branch of the radial artery, and forms a posterior carpal arch. The metacarpal, often a branch of the preceding, passes along the inner border of the metacarpal bone of the little finger, and forms the dorsal collateral branch of that finger. The communicating or deep ulnar branch arises close to the annular ligament, and dips between the abductor minimi digiti and flexor brevis to inosculate with the termination of the deep palmar arch. It is accompanied by the deep palmar branch of the ulnar nerve. The digital branches, four in number, are given off from the convexity of the superficial palmar arch. The first and smallest is distributed to the ulnar side of the little finger. The other three are short trunks, which divide between the heads of the metacarpal bones, and form the collateral branch of the radial side of the little finger, the collateral branches of the ring and middle finger, and the collateral branch of the ulnar side of the index finger. On the last phalanx, the collateral arteries communicate and form an arch, from which numerous branches are given off to the tip of the finger. The arteries of the hand are subject to frequent variety of distri- bution. The thoracic aorta commences at the lower border and left side of the fifth dorsal vertebra, passes slightly to the right as it descends, and terminates in front of the last dorsal vertebra by passing through the aortic opening of the diaphragm. Relations.—The artery is situated in the posterior mediastinum of the thorax, and has behind it the vertebral column and vena azygos minor. The oesophagus lies first to its right side, then in front, and at the upper surface of the diaphragm is placed to the left of the artery although still in front of it. THORACIC AORTA. BRANCHES OF THE THORACIC AORTA. Plan of the Relations of the Thoracic Aorta. In Front. Left pulmonary artery, Left bronchus, Pericardium, CEsophagus. Right Side. (Esophagus (above), Vena azygot .major, Thoracic duct. Thoracic Aorta. Left Side. Pleura, Left lung, (Esophagus (below). Behind. Vertebral column, Vena azygos minor. Branches.—The branches of the thoracic aorta are as follows :— Pericardiac, Bronchial, (Esophageal, Posterior mediastinal, The pericardiac arteries are a few small and irregular branches distributed to the pericardium. The BRONCHIAL ARTERIES, generally three in number, one for the right lung, and two for the left, vary both in size and origin ; the right often proceeding from a short trank common to it and one of the left bronchial branches, or from the first aortic inter- costal. They take their course to the back of the root of the lung, and accompany the ramifications of the bronchial tubes through its substance, giving twigs also to the bronchial glands, oesophagus, and pericardium. The (ESOPHAGEAL ARTERIES, four or five in number, arise from the anterior part of the aorta, and are distributed to the oeso- phagus, establishing a chain of anastomoses along that tube : the superior inosculate with the bronchial arteries, and with oesophageal branches of the inferior thyroid arteries ; the inferior with similar branches of the phrenic and gastric arteries. The posterior mediastinal arteries are small twigs distributed to the lymphatic glands and areolar tissue of the posterior medias- tinum. The INTERCOSTAL arteries arise from the posterior part of the aorta ; they are nine in number at each side, the upper two inter- costal spaces being supplied by the superior intercostal branch of the subclavian. The right intercostals are longer than the left, on account of the position of the aorta. They ascend somewhat obliquely from their origin, and cross the vertebral column behind the thoracic duct, vena azygos major, and sympathetic nerve, to the intercostal spaces ; the left passing beneath the superior intercostal vein, vena azygos minor, and sympathetic. In the intercostal space, Intercostal. 418 ABDOMINAL AORTA. or rather on the external intercostal muscle, each artery gives off a dorsal branch, which passes hack between the transverse processes of the vertebra?, lying internally to the middle costo-transverse liga- ment, and divides into a spinal branch, which supplies the spinal cord and vertebrae, and a muscular branch, distributed to the muscles and integument of the back. The intercostal artery then comes into relation with its vein and nerve, the former being above, the latter below, and ascends obliquely to the lower border of the rib, with which it conies into relation near the angle of the bone. It then runs along the lower border of the rib, lying between the two planes of intercostal muscles to the front of the chest, where it inosculates with the superior anterior intercostal branch of the in- ternal mammary. Besides the dorsal branch and several small muscular branches, the intercostal artery, at about the middle of its course, gives off a large inferior branch, which runs along the upper border of the rib below to the fore-part of the chest, and inosculates with the inferior anterior intercostal branch of the internal mammary. While between the two planes of intercostal muscles, the inter- costal artery is protected from pressure by little tendinous arches thrown across it and attached by each extremity to the bone. The upper pair of intercostal arteries inosculate with the superior inter- costals of the subclavian ; the lower intercostals anastomose with the lumbar and epigastric arteries in the parietes of the abdomen. ABDOMINAL AORTA The abdominal aorta enters the abdomen through the aortic open- ing of the diaphragm, and between the two pillars of that muscle. In its course downwards, it lies on the vertebral column to the left of the middle line, and terminates on the fourth lumbar vertebra, by dividing into the two common iliac arteries. Its point of bifurca- tion is situated a little below and to the left of the level of the umbilicus. Plan of the Relations of the Abdominal Aorta. In Front. Lesser omentum and stomach, Branches of coeliac axis and solar plexus, Splenic vein, Pancreas, Left renal vein, Transverse duodenum, Mesentery, Aortic plexus. Right Side. Right crus of diaphragm, Vena cava, Right semilunar ganglion, Thoracic duct, Vena azygos major. Abdominal Aorta. Left Side. Left semilunar ganglion Left supra-renal capsuL Sympathetic nerve. CCELIAC AXIS. 419 Behind. Thoracic duct, Receptaculum chyli, Left lumbar veins, Vertebral column. Branches.—The branches of the abdominal aorta are the following Phrenic, Inferior mesenteric, Supra-renal, Renal, Lumbar, Sacra media. Cceliac axis, Gastric, Hepatic, Splenic, Superior mesenteric, Spermatic, The PHRENIC ARTERIES are given off (frequently by a common trunk) from the anterior part of the aorta as soon as that vessel lias emerged through the aortic opening. Passing obliquely outwards on the under surface of the diaphragm, each artery divides into two branches, an internal branch, which runs forwards and inosculates with its fellow of the opposite side in front of the oesophageal open- ing ; and an external branch, which proceeds outwards towards the great circumference of the muscle, and sends branches to the supra- renal capsules. The phrenic arteries inosculate with branches of the internal mammary, intercostal, epigastric, oesophageal, gastric, hepatic, and supra-renal arteries. They are not unfrequently de- rived from the coeliac axis, or from one of its divisions, and some- times they give origin to the supra-renal arteries. The CCELIAC AXIS is the first single trunk given off by the abdominal aorta. It arises opposite the upper border of the first lumbar vertebra, is about half an inch in length, and divides into three large branches, gastric, hepatic, and splenic. Relations.—The trunk of the cadiac axis has in relation with it, in front, the lesser omentum ; on the right side, the right semilunar ganglion and lobus Spigelii of the liver ; on the left side, the left semilunar ganglion and cardiac portion of the stomach ; and below, the upper border of the pancreas and lesser curve of the stomach. It is completely surrounded by the solar plexus. The GASTRIC ARTERY (coronaria ventriculi), the smallest of the three branches of the cadiac axis, ascends between the two layers of the lesser omentum to the cardiac orifice of the stomach, then runs along the lesser curvature to the pylorus, and inosculates with the pyloric branch of the hepatic. It is distributed to the lower extremity of the oesophagus and lesser curve of the stomach ; and anastomoses with the oesophageal arteries, vasa brevia of the splenic artery, and pyloric branch of the hepatic artery. The HEPATIC ARTERY curves forward, and ascends along the right border of the lesser omentum to the liver, where it divides into two branches (right and left), which enter the transverse fissure, and are distributed along the portal canals to the right and left lobes.* * For the mode of distribution of the hepatic artery within the liver, see the “Structural Anatomy ” of that organ in the Part on Splanchnology. 420 ABDOMINAL AORTA. It is in relation, in the right border of the lesser omentum, with the ductus communis choledochus and por- tal vein, lying to the left of the former structure and on a plane anterior to tin- latter ; it is surround- ed by the hepatic- plexus of nerves, and numerous lympha- tics. There are some- times two hepatic- arteries, in which case one is derived from the super ior mesenteric. The branches <>f the hepatic artery are the— Pyloric, Gastro-duodenal, G astro - epiploica dextra, Pancreatico - duo- denalis superior, Cystic. The pyloric branch, given oti f rom the hepatic neai the pylorus,runs from left to right along the lesser curve of the stomach, where it in- osculates with the gastric artery, and gives branches to the coats of the stomach and to the lessei omentum. The gastro-duo- denal artery is a short but large trunk, which descends be- hind the pylorus, and divides into two branches, the gastro- epiploica dextra, and pancreatico-duodenalis superior. Fio. 259.—Abdominal aorta and inferior vena cava. 1. Hepatic veins (cut). 2. Phrenic arteries. 3. Vena cava. 4. Cceliac axis (cut). 5. Supra-renal capsule. 6. Superior mesenteric artery (cut). 7. Supra-renal artery. 8. Renal vein. 9. Renal artery. 10. Left spermatic vessels. 11. Right ureter. 12. Inferior mesenteric artery. 13. Right spermatic vein. 14. A lumbar artery. 15. Psoas magnus muscle. 16. Left common iliac arteiy. 17. Right common iliac vein. 18. Sacra media artery. CCELIAC AXIS. 421 The gastro-epiploica dextra runs along the great curve of the stomach, lying between the two layers of the great omentum, and inosculates at about its middle with the gastro-epiploica sinistra, a Fig. 260.—Branches of cceliac axis. 1. Hepatic artery. 2. Diaphragm. 3. Pyloric branch of the hepatic artery. 4. Right phrenic. 5. Round ligament of liver. 6 , (Esophagus. 7. Cystic artery. 8. Abdominal aorta. 9. Gall-bladder. 10. Coeliao axis. 11. Common bile duct. 12. Gastric artery. 13. Gastro-duodenal artery. 14. Vasa brevia. 15. Liver. 16. Spleen. 17. Superior pancreatico-duodenal artery, g 18. Gastro-epiploica sinistra. 19. Head of pancreas. 20. Splenic artery. 21. Duo- denum. 22. Superior mesenteric artery. 23. Gastro-epiploica dextra. 24. Pan- creas (drawn down). 25. Great omentum. branch of the splenic artery. It supplies the greater curve of the stomach and great omentum ; hence its name. The pancreatico-duodenalis superior curves along the fixed border of the duodenum, partly concealed by the attachment of the pancreas, and is distributed to the pancreas and duodenum. It inosculates interiorly with the inferior pancreatico-duodenalis and pancreatic branches of the superior mesenteric artery. 422 ABDOMINAL AORTA. The cystic artery, generally a branch of the right hepatic, is of small size, and ramifies between the coats of the gall-bladder, pre- viously to its distribution to the mucous membrane. The SPLENIC ARTERY, the largest of the three branches of the coeliac axis, passes horizontally to the left along the upper border of the pancreas, and divides into five or six large branches, which enter the hilum of the spleen, and are distributed to its structure. In its course the vessel is tortuous and serpentine, frequently making a complete turn upon itself. It lies in a narrow groove in the upper border of the pancreas, and is accompanied by the splenic vein which lies beneath it, and by the splenic plexus of nerves. The branches of the splenic artery are the— Pancreatic* parvae, Pancreatica magna, Vasa brevia, Gastro-epiploica sinistra. The pancreatic* parvse are numerous small branches distributed to the pancreas, as the splenic artery runs along its upper border. One of these, larger than the rest, follows the course of the pancreatic duct, and is called pancreatica magna. The vasa brevia are five or six branches of small size which pass from the extremity of the splenic artery and its terminal branches, between the layers of the gastro-splenic omentum, to the great end of the stomach, to which they are distributed, inosculating with branches of the gastric artery and gastro-epiploica sinistra. The gastro-epiploica sinistra appears to be the continuation of the splenic artery ; it passes forwards from left to right, along the great curve of the stomach, lying between the layers of the great omentum, and inosculates with the gastro-epiploica dextra. It is distributed to the greater curve of the stomach and great omentum. The SUPERIOR MESENTERIC ARTERY, the second of the single trunks, and next in size to the coeliac axis, arises from the aorta immediately below that vessel, and behind the pancreas. It passes forwards between the pancreas and transverse duodenum, and de- scends within the layers of the mesentery, to the right iliac fossa, where it terminates, much reduced in size. In its course it forms a curve, the convexity being to the left, the concavity to the right; is in relation near its commencement with the portal vein, and is ac- companied by the vein of the same name, which lies in front of it, and by the superior mesenteric plexus of nerves. The branches of the superior mesenteric artery are— Pancreatico-duodenalis inferior, Yasa intestini tenuis, Ileo-colica, Colica dextra. Colica media. The pancreatico-duodenalis inferior is a small branch which arises from the superior mesenteric while behind the pancreas, and curves upwards along the line of junction of the pancreas, and duo- denum. It supplies both those organs, and inosculates with the pancreatico-duodenal branch of the hepatic. SUPERIOR MESENTERIC ARTERY. 423 The vasa intestini tenuis arise from the convexity of the superior mesenteric artery. They vary from fifteen to twenty in number, and are distributed to the small intestine from the duodenum to the ter- mination of the ileum. In their course between the layers of the mesentery, they form a series of arches by the inosculation of their larger branches ; from these are developed secondary arches, and from the latter a third series of arches, from which the branches Fig. 261.—Course and distribution of the superior mesenteric artery. 1. Descending portion of the duodenum. 2. Transverse portion. 3. Pancreas. 4. Jejunum. 5. Ileum. 6. Ctecum and appendix vermiformis. 7. Ascending colon. 8. Trans- verse colon. 9. Descending colon. 10. Superior mesenteric artery. 11. Colica media. 12. The branch which inosculates with the colica sinistra. 13. Pancreatico- duodenalis inferior. 14. Colica dextra. 15. Ileo-colica. 16, 16. Vasa intestini tenuis. arise which are distributed to the coats of the intestine. From the middle branches a fourth and sometimes even a fifth series of arches is produced. By means of these arches a direct communication is established between all the branches given off from the convexity of the superior mesenteric artery; the upper branch inosculates with the inferior pancreatico-duodenal, the lower with the ileo-colic. The ileo-colic artery is the last branch given off by the concavity 424 ABDOMINAL AORTA. of the superior mesenteric. It descends to the right iliac fossa, and divides into branches which communicate and form arches, from which branches are distributed to the termination of the ileum, caecum, and commencement of the colon. This artery inosculates on the one hand with the termination of the mesenteric trunk ; on the other, with the colica dextra. The colica dextra arises from about the middle of the concavity of the superior mesenteric, and passing outwards behind the peri- toneum, divides into branches which form arches, and are distri- buted to the ascending colon. Its descending branches inosculate with the ileo-colic, the ascending with the colica media. The colica media arises from the upper part of the concavity of the superior mesenteric, and passes forward between the layers of the transverse mesocolon, where it forms arches, and is distributed to the transverse colon. It inosculates on the right with the colica dextra ; on the left, with the colica sinistra, a branch of the inferior mesenteric artery. The SPERMATIC ARTERIES are two small vessels which arise from the front of the aorta below the superior mesenteric ; from their origin each artery passes obliquely outwards, and accompanies the corresponding ureter along the front of the psoas muscle, to the border of the pelvis, where it is in relation with the external iliac artery. It is then directed outwards to the internal abdominal ring, and follows the course of the spermatic cord, along the spermatic canal and through the scrotum to the testicle, to which it is distri- buted. The right spermatic artery lies in front of the vena cava, and both vessels are accompanied by veins and by the spermatic plexuses of nerves. They anastomose with the deferential arteries, branches of the superior vesical, and with the cremasteric arteries. The ovarian arteries in the female correspond to the spermatic in the male. They descend into the pelvis and pass between the two layers of the broad ligaments of the uterus, to be distributed to the broad ligaments, ovaries, Fallopian tubes, and round ligaments; along the latter they are continued to the inguinal canal and labium at each side. They inosculate with the uterine arteries. The INFERIOR MESENTERIC ARTERY, smaller than the superior, arises from the abdominal aorta, about two inches below the origin of the latter vessel, and descends between the layers of the left meso- colon, to the left iliac fossa, where it divides into three branches:— Colica sinistra, Sigmoid, Superior hsemorrhoidal. The colica sinistra is distributed to the descending colon ; it passes upwards and outwards behind the peritoneum, and divides into two branches, one of which ascends to inosculate with the colica media, while the other descends to communicate with the sigmoid branch. The inosculation of the colica sinistra with the colica media is the largest arterial anastomosis in the body. The sigmoid artery passes obliquely outwards behind the peri- INFERIOR MESENTERIC ARTERY. 425 toneuin and divides into branches which form arches, and are dis- tributed to the sigmoid flexure of the colon. The superior branch inosculates with the colica sinistra, the inferior with the superior hpemorrhoidal artery. The superior haemorrhoidal artery is the continuation of the Fig. 262.—Branches of the inferior mesenteric artery. 1, 1. The superior mesenteric, and small intestines turned over to the right side. 2. Caecum and appendix ver- miformis. 3. Ascending colon. 4. Transverse colon drawn upwards. 5. Descending colon. 6. Sigmoid flexure. 7. Rectum. 8. Aorta. 9. Inferior mesenteric artery. 10. Colica sinistra, inosculating with (11) colica media. 12,12. Sigmoid branches. 13. Superior haemorrhoidal artery. 14. Pancreas. 15. Descending portion of the duodenum. inferior mesenteric. It crosses the ureter and left common iliac artery, and descending between the two layers of the mesorectum, is distributed to the rectum as far as its middle, anastomosing with the middle and inferior hsemorrhoidal arteries, branches derived from the internal iliac artery. 426 ABDOMINAL AORTA. The SUPRA-RENAL (capsular) are two small vessels which arise from the aorta immediately above the renal arteries, and are distri- buted to the supra-renal capsules. They are sometimes branches of the phrenic or of the renal arteries. The RENAL ARTERIES (emulgent) are two large trunks given oil from the sides of the aorta immediately below the superior mesen- teric artery ; the right is longer than the left, on account of the position of the aorta, and passes behind the vena cava to the kidney of that side. The left is somewhat higher than the right. They divide into several large branches previously to entering the kidney, and ramify very minutely in its vascular portion. The renal arteries supply several small branches to the supra-renal capsules, and one to the ureter. The renal arteries are subject to great variation in their number and place of origin. Frequently two or three branches arise from different parts of the aorta; in other instances a single trunk springs from the front of the aorta, and divides into two branches, one for each kidney; other cases are recorded where the renal arteries spring from the common iliac, inferior mesenteric, middle sacral, and even from the internal iliac. The LUMBAR ARTERIES are four in number at each side ; they correspond with the intercostals in the chest. Each artery curves around the body of the lumbar vertebra beneath the psoas muscle, and divides into two branches: one, dorsal branch, passes backwards between the transverse processes, and is distributed to the vertebrae and spinal cord and muscles of the back ; the other, parietal branch, taking its course behind the quadratus lumborum, supplies the abdominal muscles, and inosculates with branches of the internal mammary and epigastric arteries in front, the terminal twigs of the intercostals above, and the ilio-lumbar and circumflex iliac below. The first lumbar artery runs along the lower border of the last rib ; the last, along the crest of the ilium. In passing between the psoas muscle and the vertebrae, they are protected by a series of tendinous arches, which defend them and the communicating branches of the sym- pathetic nerve from pressure, during the action of the muscle. The SACRA MEDIA arises from the posterior part of the aorta just above its bifurcation, and descends along the middle of the anterior surface of the sacrum to the first piece of the coccyx, where it ter- minates by inosculating with the lateral sacral arteries. It dis- tributes branches to the rectum and anterior sacral nerves, and inosculates at either side with the lateral sacral arteries. Coccygeal Gland or Luschka’s Gland.—Lying in front of the coccyx near its tip is a small mass, connected with the extremity of the middle sacral artery, and named by Luschka, who first described it, the coccygeal gland. It consists of a number of small arteries with terminal dilatations like minute aneurisms, held together by fibrous tissue, which also forms a capsule for the whole mass ; in the meshes of the stroma one or two ganglion cells are found, and a few small nerves derived from the sympathetic prevertebral chain. It appears to be the remains of foetal tissues. COMMON ILIAC ARTERIES. 427 Varieties in the Branches of the Abdominal Aorta.—The phrenic arteries are very rarely both derived from the aorta. One or both may be branches of the cceliac axis ; one may proceed from the gastric artery, from the renal, or from the upper lumbar. There are occasionally three or more phrenic arteries. The cceliac axis is variable in length, and gives off its branches irregularly. There are sometimes two or even three hepatic arteries, one of which may be derived from the gastric or from the superior mesenteric. The colica media is sometimes derived from the hepatic artery. The spermatic arteries are variable both in origin and number. The right spermatic may be a branch of the renal; the left, of the in- ferior mesenteric. The supra-renal arteries may be derived from the phrenic or renal arteries. COMMON ILIAC ARTERIES, The abdominal aorta divides opposite the fourth lumbar vertebra (or the intervertebral substance between the fourth and fifth) into the two common iliac arteries. Sometimes the bifurcation takes place as high as the third, and occasionally as low as the fifth. The common iliac arteries are about two inches in length ; they diverge from the termination of the aorta, and pass downwards and outwards at each side to the margin of the pelvis, opposite the sacro-iliac sym- physis, where they divide into the internal and external iliac. In old persons the common iliac arteries are more or less dilated and curved in their course. The right artery is somewhat longer than the left, and forms a more obtuse angle with the termination of the aorta ; the angle of bifurcation is greater in the female than in the male. Relations.—The relations of the two arteries are different at the two sides of the body. The right common iliac is in relation in front with the peritoneum, small intestines and sympathetic nerves, and is crossed at its bifurcation by the ureter. It is in relation behind with the two common iliac veins and last lumbar vertebra, and externally with the psoas magnus, vena cava, and right common iliac vein. The left is in relation in front with the peritoneum and sympathetic nerves, and is crossed by the rectum and superior hsemorrlioidal artery, and, at its bifurcation, by the ureter. It is in relation behind with the left common iliac vein and last lumbar vertebra, and externally with the psoas magnus. The INTERNAL ILIAC ARTERY is a short trunk, varying in length from an inch to two inches. It descends obliquely forwards to a point opposite the upper margin of the great sacro-iscliiatic foramen, where it divides into an anterior and a posterior trunk. In the foetus, the internal iliac artery, under the name of hypogastric or umbilical, is continued onwards by the side of the upper part of the bladder to near its apex, whence it ascends by the side of the linea alba and urachus to the umbilicus, where it becomes the true um- bilical artery. After birth, this artery ceases to be pervious beyond 428 INTERNAL ILIAC ARTERY. the side of the bladder, and the obliterated portion is converted into a fibrous cord. The projection of the two cords on the inner wall of the abdomen causes the depression at each side, which goes by the name of feritoneal fossa. Fio. 263.—Iliac arteries. 1. Aorta. 2. Left common iliac artery. 3. External iliac. 4. Deep epigastric artery. 5. Deep circumflex iliac. 6. Internal iliac artery. 7. Its anterior trunk. 8. Its posterior trunk. 9. The pervious portion of the umbilical artery giving off (10) the superior vesical artery, n. Internal pudic artery passing behind the spine of the ischium (12) and lesser sacro-ischiatic liga- ment. 13. Middle hsemorrhoidal artery. 14. Iscliiatic artery, also passing behind the lesser sacro-ischiatic ligament to escape from the pelvis. 16. Ilio-lumbar ascending to inosculate with the circumflex iliac artery (5) and form an arch along the crest of the ilium. 17. Obturator artery. 18. Lateral sacral. 19. Gluteal artery passing through the upper part of the great sacro-ischiatic foramen. 20. Sacra media. 21. Right common iliac artery cut short. 22. Femoral artery. Plan of the Relations of the Internal Iliac Artery. In Front. Peritoneum. Ureter. Outer bide. \ T Psoas magnus. _ Internal Iliac. Behind. Internal iliac vein, bumbo-sacral nerve, Pyriformis muscle. Branches.—The branches of the anterior trunk are the :— Superior vesical, Inferior vesical, Middle haemorrhoidal, Uterine (in female), Vaginal (in female), Obturator, Ischiatic, Internal pudic. Tbe branches of the posterior trunk are the :— Ilio-lumbar, Gluteal. Lateral sacral, PLATE 24. SIDE VIEW OF MALE PELVIS A. Sacrum. B. External iliac artery. C. Upper end of rectum. D. Ramus of pubes. E. Spine of ischium (cut off). G. Bladder covered by peritoneum. G*. Bladder, uncovered by peritoneum. H. Peritoneum reflected from side of bladder. I. Yas deferens. K. Ureter. L. Vesicula seminalis. M. Spermatic cord. N. Crus penis. O. Urethra, o. Bulb. P. Sphincter ani. QL. Coccyx. R. Great sacro-sciatic ligament. S. Internal iliac artery. T. Sacral nerves. U. Pyriformis muscle. V. Internal pudic artery. W. Levator ani muscle. X. Triangular ligament (cut). PLATE 24. BRANCHES OF THE INTERNAL ILIAC. 429 The superior vesical arteries are three or four small branches, which proceed from the pervious portion of the umbilical artery. They are distributed to the upper and middle part of the bladder. From one of these there passes off a small artery, the deferential, which accompanies the vas deferens to the spermatic cord. The inferior vesical, somewhat larger than the preceding, passes down upon the side of the bladder to its base, and is distributed to that region, the vesiculse seminales, and prostate gland. The middle haemorrhoidal artery, frequently a branch of the preceding, passes downwards to the rectum, to which it is distri- buted, inosculating with the superior and inferior haemorrhoidal arteries. In the female it distributes branches to the vagina. The uterine artery passes inwards between the layers of the broad ligament to the neck of the uterus, and ascends in a tortuous course along its lateral border. It gives branches to the vagina, lower part of the bladder, Fallopian tube (tubaria), ovary (ovaria), and round ligament, and inosculates with the spermatic or ovarian artery. The vaginal artery corresponds in position with the inferior vesical in the male, and is distributed to the vagina and neighbour- ing parts of the bladder and rectum. The OBTURATOR ARTERY (arising frequently from the posterior trunk of the internal iliac) passes forwards from the ante- rior trunk, a little below the brim of the pelvis, to the upper border of the obturator fora- men. Escaping from the pel- vis through a tendinous arch formed by the obturator mem- brane, it divides into two branches, internal and exter- nal. Its branches within the pel- vis are—an iliac branch, which supplies the bone of the iliac fossa, and inosculates with the ilio-lumbar artery ; and a rpuhic branch which is given off close to the obturator fora- men, and inosculates with its fellow of the opposite side, behind the pubes, and with the pubic branch of the deep epigastric artery. The internal branch curves inwards around the bony margin of the obturator foramen, and distributes twigs to the obturator and adductor muscles, inosculating with the internal circumflex artery of the femoral. The external branch winds around the outer margin of the obturator Branches of the Anterior Trunk. Fig. 264.—Irregular origin of obturator artery from epigastric. Second variety internal to crural ring. 430 INTERNAL ILIAC ARTERY. foramen to the space between the gemellus inferior and quadratus femoris, where it inosculates with the ischiatic artery. In its course it inosculates also with the internal circumflex, and sends a small branch through the notch in the acetabulum to supply the liga- mentum teres. The obturator artery sometimes arises from the external iliac, but more frequently from the epigastric branch of that artery, in which case it runs down directly to the obturator foramen, either on the outer or inner side of the crural ring,—if to the inner side it is in contact with Gimbernat’s ligament, and is in danger in the operation for femoral hernia; fortunately it is but rarely found in this dan- gerous position. The ISCHIATIC ARTERY is the larger of the two terminal branches of the anterior division of the internal iliac. It passes downwards in front of the pyriformis and sacral plexus of nerves, lying inter- nally to the pudic artery, to the lower part of the great ischiatic foramen, where it escapes from the pelvis between the inferior border of the pyriformis and coccygeus. It then descends in the space between the trochanter major and tuberosity of the ischium in company with the ischiatic nerves, and divides into several branches, the principal of which are—coccygeal, inferior gluteal, comes nervi ischiatici, and muscular. The coccygeal branch pierces the great sacro-ischiatic ligament, and is distributed to the coccygeus and levator ani, and to the integument around the anus and coccyx. The inferior gluteal branches, three or four in number and of large size, are distributed to the gluteus maximus muscle, anasto- mosing with branches of the superior gluteal artery. The comes nervi ischiatici is a slender branch, which accom- panies the great ischiatic nerve, extending as far as the lower part of the thigh. The muscular branches supply the muscles of the posterior part of the hip and thigh, and inosculate with the internal and ex- ternal circumflex arteries, obturator, and superior perforating ; some branches are also sent to the hip-joint. The INTERNAL PUDIC ARTERY, the other terminal branch of the anterior trunk of the internal iliac, descends externally to the ischiatic artery to the lower part of the great ischiatic foramen. It emerges from the pelvis through the great sacro-ischiatic foramen between the lower border of the pyriformis and the coccygeus, crosses the spine of the ischium, and re-enters the pelvis through the lesser sacro-ischiatic foramen ; in the next place it passes forward on the internal obturator muscle, enclosed in the sheath of obturator fascia forming Alcock’s canal, to the ramus of the ischium, being situated at about an inch from the margin of the tuberosity; it then ascends by the side of the ramus of the ischium and pubes, and near the symphysis pubis pierces the triangular ligament of the perineum and divides into two terminal branches, the artery of the corpus cavernosum and the artery of the dorsum of the penis. Branches.—The branches of the internal pudic artery within the pelvis are several small twigs to the levator ani and sacral nerves ; and occasionally a branch which takes the place of the inferior vesical or middle hamiorrhoidal artery. The branches given off externally to the pelvis are the— INTERNAL PUDIC ARTERY. Inferior hsemorrhoidal, Superficial perineal, (Transverse perineal), Artery of the bulb, Artery of the corpus eavernosum, Artery of the dorsum of the penis. The inferior hsemorrhoidal arteries are three or four small Fig. 265.—Arteries of the perineum; on the right side the superficial arteries are seen, on the left the deep. 1. The penis; the crus penis of the left side is cut through. 2. Bulbo-cavernosus muscles, enclosing the bulbous portion of the corpus spongiosum. 3. Ischio-cavernosus, spread out upon the crus penis of the right side. 4. Anus, surrounded by the sphincter ani. 3. Ramus of ischium and pubes. 6. Tuberosity of ischium. 7. Lesser sacro-ischiatic ligament. 8. Coccyx. 9. In- ternal pudic artery, crossing the spine of the ischium, and entering the perineum. 10. Inferior hsemorrhoidal branches. 11. Superficial perineal artery, giving off a small branch, transverse perineal, upon the transversus perinei muscle. 12. The same artery on the left side cut off. 13. Artery of the bulb. 14. The artery of the corpus cavernosum and artery of the dorsum of the penis. branches, given off by the internal pudic while behind the tuberosity of the ischium. They cross the ischio-reetal fossa, and are distri- buted to the anus and to the muscles and integument of the anal region of the perineum, anastomosing with the branches of the middle hsemorrhoidal. The superficial perineal artery is given off near the attachment of the crus penis ; it pierces the connecting layer of the perineal fascia and triangular ligament, and runs forward across the trans- versus perinei muscle, and along the groove between the accelerator urinse and erector penis to the septum scroti, upon which it ramifies under the name of arteria septi. It distributes branches to the scrotum and perineum. One of the latter, larger than the rest, INTERNAL ILIAC ARTERY. 432 crosses the perineum, resting on the transversus perinei muscle, and is named the transverse 'perineal. There are often two superficial perineal arteries. The artery of the bulb is given off from the pudic nearly opposite the opening for the transmission of the urethra ; it passes almost transversely inwards behind the triangular ligament, and pierces that ligament to enter the corpus spongiosum at its bulbous ex- tremity. It is distributed in the corpus spongiosum and gives a small branch downwards to Cowper’s gland. The artery of the corpus cavernosum pierces the crus penis, and runs forward in the interior of the corpus cavernosum, by the side of the septum pectiniforme. It ramifies in the parenchyma of the venous structure of the corpus cavernosum. The dorsal artery of the penis ascends between the two crura and symphysis pubis to the dorsum penis, and runs forward through the suspensory ligament, in the groove of the corpus cavernosum, to the glans, distributing branches in its course to the body of the organ and integument. The pudic artery is sometimes small, and fails to give off some of its branches ; in such cases its distribution is supplemented by a separate artery called the accessory pudic. This branch is generally derived from the pudic before that vessel passes through the great sacro-sciatic foramen, but it sometimes springs from the inferior vesical, the obturator, or some other branch of the internal iliac. It passes along the side of the base of the bladder, and the lateral aspect of the prostate gland, pierces the triangular ligament to reach the root of the penis, and divides into the artery of the bulb and the dorsal artery of the penis ; or it may terminate in the superficial perineal artery. The INTERNAL PUDIC ARTERY in the female is smaller than in the male ; its branches, with their distribution, are, in principle, the same. The superficial perineal artery supplies the homologue of the lateral half of the scrotum, namely, the greater labium. The artery of the bulb supplies the bulb of the vestibule and commencement of the vagina ; the artery of the corpus cavernosum, the cavernous body of the clitoris ; and the arteria dorsalis clitoridis, the dorsum of that organ. The ILIO-LUMBAR ARTERY passes out between the obturator nerve and lumbo-sacral cord, and ascends beneath the external iliac vessels and psoas muscle, to the posterior part of the crest of the ilium, where it divides into two branches, a lumbar branch which supplies the psoas and quad rat us lumborum, and sends a branch through the fifth intervertebral foramen to the spinal cord and its membranes ; and an iliac branch which crosses the iliac fossa to the crest of the ilium, and inosculates with the lumbar arteries and deep circumflex iliac ; in its course it distributes branches to the iliacus and abdominal muscles. Branches of the Posterior Trunk. BRANCHES OF INTERNAL ILIAC. 433 The LATERAL SACRAL ARTERIES are generally two in number on each side, superior and inferior. The superior passes inwards to the first sacral foramen, and is distributed to the contents of the spinal canal, from which it escapes by the posterior sacral foramen, and supplies the integument of the dorsum of the sacrum. The inferior passes down by the side of the anterior sacral foramina to the coccyx ; it first pierces and then rests on the origin of the pyriformis, and sends twigs into the sacral canal to supply the sacral nerves. Both arteries give branches to the pyriformis and Fig. 266.—Arteries of the buttock. 1. Superficial branch of the gluteal artery. 2. Gluteus medius (origin). 3. Gluteus maximus (origin). 4. Superior branch of deep gluteal artery. 5. Trunk of gluteal artery. 6. In- ferior branch of deep gluteal artery. 7.Pyri- formis. 8. Gluteus minimus. 9. Pudic artery. 10. Great sci- atic nerve. 11. Lesser sacro-sciatic ligament. 12. Gluteus medius (insertion). 13. Ischi- atic artery. 14. Great trochanter. 15. Coccy- geal branch of ischiatic artery. 16. Anasto- motic branch of ischi- atic. 17. Great sacro- sciatic ligament. 18. Obturator internus an d twogemelli. 19. Exter- nal sphincter ani. 20. Tendon of obturator externus. 21. Inferior liseinorrhoidal artery. 22. Insertion of gluteus maximus. 23. Tubero- sity of ischium. 24. Quadratus femoris. 26. Lesser trochanter. 27. Arteria comes nervi ischiatici. coccygeus muscles, and the sacral nerves ; they inosculate with each other and with the sacra media. The GLUTEAL ARTERY is the continuation of the posterior trunk of the internal iliac ; it passes backwards between the lumbo-sacral and first sacral nerve through the upper part of the great sacro- ischiatic foramen and above the pyriformis muscle, and divides into three branches, superficial, deep superior, and deep inferior ; while within the pelvis it gives off some muscular twigs to the iliacus and pyriformis, and at its escape from the pelvis, a nutrient artery to the ilium. EXTERNAL ILIAC ARTERY. 434 The superficial branch passes backwards between the gluteus maximus and medius, and is distributed to the gluteus maximus and to the integument of the gluteal and sacral regions. The deep superior branch passes forwards along the middle curved line of the ilium, between the gluteus medius and minimus to the anterior superior spinous process, where it inosculates with the superficial circumflex iliac and external circumflex of the femoral. There are frequently two arteries occupying the place of this branch. The deep inferior branches, two or three in number, cross the gluteus minimus obliquely to the trochanter major, where they in- osculate with branches of the external circumflex and ischiatic arteries, and send branches through the gluteus minimus to supply the capsule of the hip-joint. The EXTERNAL ILIAC ARTERY of each side passes obliquely downwards along the inner border of the psoas muscle, from opposite the sacro-iliac symphysis to the femoral arch, where it becomes the femoral artery. Plan of the Relations of the External Iliac Arterv In Front. Peritoneum, intestines, and iliac fascia, Lymphatics, Spermatic vessels, Genito-crural nerve, Circumflex iliac vein. Inner Side. External iliac vein, Yas deferens. External Iliac. Outer Side. Psoas magnus, Iliac fascia. Behind. External iliac vein, Psoas magnus. Branches.—Besides several small twigs which supply the lym- phatic glands and psoas muscle, the external iliac gives oft’ two branches, the Deep epigastric, Deep circumflex iliac. The DEEP EPIGASTRIC ARTERY arises from the front of the external iliac near Poupart’s ligament; and passing inwards between the peritoneum and transversalis fascia, ascends obliquely to the sheath of the rectus. It enters that sheath near its lower third, passes upwards behind the rectus muscle, to which it is distributed, and, in the substance of that muscle, inosculates, near the ensiform cartilage, with the termination (superior epigastric) of the internal mammary artery. It lies internally to the internal abdominal ring and immediately above the femoral ring, and is crossed near its origin by the vas deferens in the male, and the round ligament in the female. BRANCHES OF EXTERNAL ILIAC. 435 The brandies of the epigastric artery are— A cremasteric branch which accompanies the spermatic cord, and after supplying the cremaster muscle inosculates with the spermatic artery. A pubic branch which is distributed behind the pubes, and sends a small branch of communication downwards to the obturator artery. Muscular branches which pass outwards between the abdominal muscles, and inosculate with the circumflex iliac, lumbar, and in- ferior intercostal arteries. Superficial branches which pierce the rectus muscle, and are dis- tributed to the integument of the abdomen. The epigastric artery forms a prominence of the peritoneum, which divides the inguinal fossa into an internal and external portion ; it is from the former that direct inguinal hernia issues, and from the latter oblique inguinal hernia. Triangle of Hesselbach.—This is a small triangular space, bounded externally by the deep epigastric artery, internally by the outer edge of the rectus abdominis, and below by Poupart’s ligament and the crest of the pubes. In this space is situated the external abdominal ring, through which both direct and oblique inguinal hernia pass. The DEEP CIRCUMFLEX ILIAC arises from the other side of the external iliac, a little below the epigastric artery. It ascends obliquely along Poupart’s ligament, contained in a fibrous canal formed at the junction of the transversalis and iliac fascia:, and curving around the crest of the ilium, inosculates with the ilio- lumbar and inferior lumbar arteries. It gives off muscular branches to the ilio-psoas, and upper end of the sartorius and tensor vagina femoris. Opposite the anterior superior spinous process of the ilium, it gives off a lafge ascending branch, which passes upwards between the internal oblique and transversalis, and divides into numerous branches which supply the abdominal muscles, and inosculate with the inferior intercostal and the lumbar arteries. FEMORAL ARTERY. Emerging from beneath Poupart’s ligament, the external iliac artery enters the thigh and becomes the femoral. The femoral artery passes down the inner side of the thigh, from Poupart’s ligament, at a point midway between the anterior superior spinous process of the ilium and the symphysis pubis, to the opening in the adductor magnus, at the junction of the middle with the inferior third of the thigh, where it becomes the popliteal artery. The femoral artery and vein are enclosed in a strong sheath, femoral sheath, which is formed for the greater part of its extent by fibrous and areolar tissue, and by a process of fascia sent inwards from the fascia lata. Near Poupart’s ligament this sheath is much larger than the vessels it contains, and is continuous with the trans- 436 FEMORAL ARTERY. versalis and iliac fascia. If the sheath be opened at this point, the artery will be seen in contact with the outer wall of the sheath. The vein lies next the artery, being separated from it by a fibrous septum, and between the vein and the inner wall of the sheath, and divided from the vein by another thin fibrous septum, is a triangular in- terval, femoral or crural canal, into which the sac is pro- truded in femoral hernia. This space is occupied in the normal state of the parts by loose areo- lar tissue, and by lymphatic vessels which pierce the inner wall of the sheath to make their way to a gland, situ- ated in the femoral or crural ring (see Fig- 235)- Relations.— The upper third of the femora] artery is superficial, being covered only by the integument, in- guinal glands, and superficial and deep fascia. The lower two-thirds are cov- ered by the sartorius muscle. To its outer side the artery is in relation with the psoas, and vastus interims muscles, and with the femoral vein at the upper part of the thigh. Behind, it rests on the inner border of the psoas ; it is next separated from the pectineus by the femoral vein, profunda vein and artery, and then lies on the adductor longus to its termination ; near the lower border of the adductor longus it is placed in an aponeurotic sheath or canal, called Hunter’s canal, formed by an arch of tendinous fibres, thrown from the border of the adductor longus and the border of the opening in the adductor magnus, to the side of the vastus interims. To its inner side it is in relation at its Fig. 267. — Anterior and inner aspect of the thigh, with the femoral artery. 1 Lower part of the tendon of the exter- nal oblique muscle. 2. External abdomi- nal ring. 3, 3. Upper and lower part of the sartorius muscle; its middle portion being removed. 4. Hectus. 5. Vastus interims. 6. Patella. 7. Iliacus and psoas. 8. Pectineus. o. Ad- ductor longus. 10. Hunter’s canal. 11. Adductor magnus. 12. Gracilis. 13. Ten- don of the semi-teu- dinosus. 14. Femo- ral artery. 15. Su- perficial circumflex iliac artery. 2. Su- perficial epigastric artery. 16. The two external pudic ar- teries, superficial and deep. 17. Pro- funda artery, giving off (18) its external circumflex branch; and lower down the three perforating. A small bend of the internal circumflex artery (8) is seen be- hind the inner mar- gin of the femoral, just below the deep external pudic artery. 19. Theanas- tomotica magna, de- scending to the k nee, upon which it rami- fies (6). RELATIONS OF THE FEMORAL ARTERY. 437 upper part with the femoral vein, and lower down with the ad- ductor longus and sartorius. The immediate relations of the artery are the femoral vein, long saphenous nerve, and muscular nerve to the vastus internus. The vein at Poupart’s ligament lies to the inner side of the artery ; but lower down gets behind it, and inclines to its outer side. The muscular nerve lies to the outer side, and somewhat upon the sheath for the lower two-thirds of its extent; and the long saphenous nerve is situated within the sheath, and in front of the artery for the same extent. Plan of the Relations of the Femoral Artery. Front. Skin, superficial and deep fascia, Sartorius, Long saphenous nerve and vein, Genito-crural nerve, Branches of anterior crural nerve, Aponeurotic canal. Inner Side. Femoral vein, Adductor longus, Sartorius, Long saphenous nerve. Outer Side. Long saphenous nerve, Vastus internus, Femoral vein. Femoral Artery. Behind. Psoas muscle, Pectineus, Nerve to pectineus, Profunda vein, Femoral vein, Adductor longus, Adductor magnus. Branches.—-The branches of tin femoral artery are the Superficial circumflex iliac, Superficial epigastric, Superficial external pudic, Deep external pudic, Profunda, External circumflex, Internal circumflex, Three perforating. Muscular, Anastomotica magna. The superficial circumflex iliac artery arises from the femoral immediately below Poupart’s ligament, and passes obliquely outwards towards the crest of the ilium, where it pierces the fascia lata. It supplies the integument of the groin, superficial fascia, and inguinal glands, and anastomoses with the deep circumflex iliac, gluteal and external circumflex arteries. The superficial epigastric arises from the femoral immediately below Poupart’s ligament, pierces the fascia lata, and ascends obliquely towards the umbilicus between the two layers of the superficial fascia. Tt distributes branches to the inguinal glands 438 FEMORAL ARTERY. and integument, and inosculates with branches of the deep epigastric and internal mammary arteries. The superficial external pudic arises near the superficial epi- gastric artery; it pierces the fascia lata at the saphenous opening, and passes transversely inwards, crossing the spermatic cord, to be distributed to the integument of the penis and scrotum in the male, and to the labia in the female. The deep external pudic arises from the femoral a little below, and sometimes in common with, the preceding ; it crosses the femoral vein immediately below the termination of the internal saphena vein, and resting on the pectineus muscle reaches the inner border of the thigh, where it pierces the fascia lata, and is distributed to the in- tegument of the external organs of generation and perineum. Both external pudics inosculate with the internal pudic artery. The PROFUNDA FEMORIS arises from the outer and posterior side of the femoral artery about one inch and a half below Poupart’s ligament; it passes downwards and backwards and a little outwards, behind the adductor longus muscle, pierces the adductor magnus, and is distributed to the iiexor muscles on the posterior part of the thigh. It is so lai’ge that it may be considered a division of the common femoral, in which case the continuation of the main trunk may be called superficial. Plan of the Relations of tlie Profunda Artery. In Front. Femoral vein, Profunda vein, Adductor longus. Inner Side. Pectineus, Adductor brevis, Adductor magnus. Outer Side. Vastus internus, Femur. Profunda Artery. Behind. Pectineus, Iliiicus, Adductor brevis, Adductor magnus. Branches.—The branches of the profunda artery are the external circumflex, internal circumflex, and three perforating arteries. The external circumflex artery passes outwards beneath the sartorius and rectus and in front of the crureus muscle, crossing between the divisions of the crural nerve, and divides into three sets of branches: ascending, which pass upwards beneath the sar- torius, rectus, and tensor vaginae femoris, and inosculate with the terminal branches of the gluteal and circumflex iliac arteries ; de- scending, which pass downwards beneath the rectus and along the margin of the vastus externus muscle, distributing branches to the rectus, vastus externus and crureus ; some of the lower twigs can be traced as far as the knee, where they inosculate with the superior articular arteries of the popliteal ; and transverse, which continue BRANCHES OF PROFUNDA FEMORIS. 439 the original course of the artery around the thigh, pierce the vastus externus, and anastomose with branches of the ischiatic, internal circumflex, and superior per- forating arteries. The external circumflex sup- plies the muscles of the anterior and outer side of the thigh. The internal circumflex artery windsaround the inner side of the neck of the femur, passing between the pectineus and psoas, and over the upper border of the adductor brevis to the tendon of the obturator externus, which it accompanies to the space between the quadratus femoris and upper border of the adductor magnus. While on the obturator externus it gives off a branch which is distributed to that muscle, the adductor brevis, and gracilis, and anastomoses with the obturator artery. It next gives off an articular branch, which enters the hip-joint through the notch in the acetabulum; and terminates in several branches which inosculate with the is- chiatic, external circumflex, and superior per- forating arteries. The superior perforating artery passes back- wards near the lower border of the pectineus, pierces the adductor brevis and magnus near the femur, and is distributed to the posterior mus- cles of the thigh ; inosculating with the circum- flex, ischiatic, and middle perforating arteries. The middle perforating artery pierces the tendons of the adductor brevis and magnus, and is distributed like the superior ; inosculat- ing with the superior and inferior perforating. From this branch is given off the nutrient artery of the femur. The inferior perforating artery is given off below the adductor brevis, and pierces the ten- don of the adductor magnus, supplying it and the flexor muscles, and inosculating with the middle perforating artery above, and the articular branches of the popliteal below. It is through the medium of the branches of the profunda which inosculate above with branches of the internal iliac, and below with those of the pop- liteal artery, that the collateral circulation is maintained in the limb after ligature of the femoral artery. The muscular branches are given off by the femoral artery throughout the whole of its course. They supply the muscles in immediate proximity with the artery, particularly those of the Pig. 268.—Scheme of profunda femoris ar- tery. 1. Quadratus femoris. 2. Obturator externus. 3. Psoas. 4. Pectineus. 5. Ad- ductor brevis. 6. Ad- ductor longus. 7. Adductor magnus. 8. Common femoral artery. 9. Profunda femoris. 10. Internal circumflex. 11. Supe- rior perforating. 12. Middle perforating. 13. Inferior perforat- ing. 14. Termination of profunda. 15. Oval opening in adductor magnus. 16. Anasto- motica magna. 440 POPLITEAL SPACE. anterior aspect ot the thigh. One ot these branches, larger than the rest, arises from the femoral immediately below the origin of the profunda, and passing outwards between the sartorius and rectus, divides into branches, which are distributed to all the muscles of the anterior aspect of the thigh. This may be named the superior muscular artery. The anastomotica magna arises from the femoral near its ter- mination at the opening in the adductor magnus, and divides into a superficial and deep branch. The superficial branch accompanies the internal saphenous nerve to the knee, and piercing the fascia lata is distri- buted to the integument. The deep branch passes onwards through the substance of the vastus internus muscle, resting on the tendon of the ad- ductor magnus to the knee, where it inoscu- lates with the internal articular branches of the popliteal, and the recur- rent of the anterior tibial. It also sends a branch through the vastus inter- nus, which supplies the synovial membrane of the joint, and inosculates with the superior exter- nal articular artery and external circumflex. POPLITEAL SPACE. This is a space of a diamond shape, situated at the back of the knee- joint. It is bounded be- low by the outer and inner heads of the gas- trocnemius, above by the outer and inner ham- strings, in front by the posterior ligament of the knee-joint, and is covered in behind by the fascia lata of the thigh. It con- tains the popliteal vessels and their branches, the divisions of tin* ' ' '4 Fig. 269.—Popliteal space. 1. Branch of the small sciatic nerve (cut). 2. Biceps and external pop- liteal nerve. 3. Semi-tendinosus. 4. Internal pop- liteal nerve. 5. Semi-membranosus. 6. Popliteal vein. 7. Superior internal articular artery and nerve. 8. Popliteal artery. 9. Gracilis. 10. Supe- rior external articular artery and nerve, it. Sar- torius. 12. Plantaris. 13. Gastrocnemius, inner head; 14. Gastrocnemius, outer head. 15. Short saphenous nerve. 16. Communicans peronei nerve. 17. External saphena vein. 19. Long saphe- nous nerve. POPLITEAL ARTERY. great sciatic nerve, termination of the external saphena vein, branches of the obturator and lesser sciatic nerves, lymphatic glands, and areolar tissue. The popliteal artery lies at the bottom of this space, immediately in contact with the ligamentum posticum Winslowii, the vein lying superficial to it, and the internal popliteal nerve superficial to both vein and artery; the external popliteal nerve (perineal) descends on the outer side of the space, in contact with the biceps tendon, and the lymphatic glands (four or five in number) surround the artery. 441 POPLITEAL ARTERY. The popliteal artery (Fig. 269) commences from the termination of the femoral at the opening in the adductor magnus muscle, and passes obliquely outwards through the middle of the popliteal space to the lower border of the popliteus muscle, where it divides into the anterior and posterior tibial arteries. In structure the popliteal artery is remarkable for the thickness of its walls. Plan of the Relations of the Popliteal Artery. Superficially. Semi-membranosus, Popliteal nerve, Popliteal vein, Gastrocnemius, Plantaris, Soleus. Outer Side. Biceps, External condyle, Gastrocnemius, Plantaris, Soleus. Inner Side. Semi-membranosus, Internal condyle, Gastrocnemius. Popliteal Artery. Deeply. Femur, Ligamentum posticum Winslowii, Popliteal fascia, Popliteus. Branches.—The branches of the popliteal artery are the— Superior external articular, Superior internal articular, Azygos articular, Cutaneous, Inferior external articular, Inferior internal articular, Muscular, Superior, Inferior, or Sural. The superior articular arteries, external and internal, wind around the femur, immediately above the condyles, to the front of the knee-joint, anastomosing with each other, with the external circumflex, anastomotica magna, inferior articular, and recurrent of the anterior tibial. The external passes beneath the tendon of the 442 POPLITEAL ARTERY. biceps, and the internal through an arched opening beneath the tendon of the adductor magnus. They supply the knee-joint and lower part of the femur, and give branches to the vasti muscles. The azygos articular artery pierces the posterior ligament of the joint, the ligamentum posticum Winslowii, and supplies the crucial ligaments and synovial membrane. There are, frequently, ■several posterior articular arteries. Cutaneous branches pass out between the two heads of the gastrocnemius and are distributed to the skin and subcutaneous Fat of the calf. The inferior articular arteries wind around the head of the tibia immediately be- low the joint, and anas- tomose with each other, the superior articular arteries, and the re- current of the anterior tibial. The external passes beneath the long external lateral liga- ment of the joint, the i nternal beneath the in - ternal lateral ligament. They supply the knee- joint and the heads of the tibia and fibula. The muscular branches consist of a superior and inferior set: the former arise from the upper part of the artery and are distributed to the vas- tus externus and ham- string muscles ; the latter, called also the sural arteries, pass to the two heads of the gastrocnemius. ANTERIOR TIBIAL ARTERY. The anterior tibial artery passes forwards between the two heads of the tibialis posticus muscle, and through the opening in the upper part of the interosseous membrane, to the Fro. 270.—Anterior aspect of the leg and foot, showing the anterior tibial and dorsalis pedis arteries ; the tibialis an- ticus has been removed. 1. Tendon of insertion of the quadriceps ex- tensor muscle. 2. In- sertion of the ligamen- tum patellar into the lower border of the pa- tella. 3. Tibia. 4. Ex- tensor proprius hallucis muscle. 5. Extensor longus digitorum. 6. The peronei. 7. Inner belly of the gastrocne- mius and soleus. 8. An- nular ligament. 9. An- terior tibial artery. 10. Its recurrent branch inosculating with (2) in- ferior external articular, and (1) superior exter- nal articular arteries, branches of the popli- teal. ii. Internal mal- leolar artery. 17. Ex- ternal malleolar inoscu- lating with the anterior peroneal artery (12). 13. Dorsalis pedis artery. 14. Tarsal and metatar- sal branches. 15. Dor- salis hallucis artery. 16. Continuation of the dorsalis pedis into the sole of the foot. RELATIONS OF ANTERIOR TIBIAL. anterior tibial region. It then runs down the anterior aspect of the leg to the ankle-joint, where it becomes the dorsalis pedis. Relations.—In its course it rests on the interosseous membrane (to which it is connected by a little tendinous arch which is thrown across it), the lower part of the tibia, and the anterior ligament of the joint. In its upper third it is situated between the tibialis anticus and extensor longus digitorum, lower down between the tibialis anticus and extensor proprius hallucis ; and just before it reaches the ankle it is crossed by the tendon of the extensor proprius hallucis, and becomes placed between that tendon and the tendons of the extensor longus digitorum. Its immediate relations are the venae comites and anterior tibial nerve ; the latter lies at first to its outer side, at about the middle of the leg it is placed superficially to the artery, and at the ankle is again at its outer side. 443 Plan of the Relations of the Anterior Tibial Artery Front. Integument, superficial and deep fascia, Tibialis anticus, Extensor longus digitorum, Extensor proprius hallucis, Anterior tibial nerve. Outer Side. Anterior tibial nerve, Extensor longusdigitorum, Extensorproprius hallucis, Tendons of extensor lon- gus digitorum. Inner Side. Tibialis anticus, Tendon of extensor pro- prius hnllucis. Anterior Tibial Artery. Behind. Interosseous membrane. Tibia (lower fourth), Ankle-joint. Branches.—The branches of the anterior tibial artery are the- Recurrent, Muscular, External malleolar, Internal malleolar. The recurrent branch (anterior tibial recurrent) passes upwards beneath the origin of the tibalis anticus muscle to the front of the knee-joint, upon which it is distributed, anastomosing with the articular branches of the popliteal artery. The muscular branches are numerous ; they supply the muscles of the anterior tibial region. Some of them pass through the interos- seous membrane to the muscles of the back of the leg and anastomose with branches of the posterior tibial and peroneal. The malleolar arteries are distributed to the ankle-joint; the external, passing beneath the tendons of the extensor longus digitorum and peroneus tertius, inosculates with the anterior peroneal artery and dorsalis pedis ; the internal, beneath the tendons of the extensor 444 DORSALIS PEDIS ARTERY. proprius hallucis and tibialis anticus, inosculates with branches of the posterior tibial and internal plantar arteries. They supply branches to the ankle-joint. The DORSALIS PEDIS ARTERY is continued forward along the tibial side of the dorsum of the foot, from the ankle to the base of the metatarsal bone of the great toe, where it divides into two branches, one of which dips between the two heads of the first dorsal interosseous muscle into the sole of the foot, and becomes continuous with the deep plantar arch ; the other, called dorsalis hallucis, runs forward in the first interosseous space. Relations.—It runs along the outer border of the tendon of the extensor proprius hallucis ; at its fibular side is the innermost tendon of the extensor longus digitorum, and near its termination it is crossed by the inner tendon of the extensor brevis digitorum. It is accompanied by veme comites, and has the continuation of the anterior tibial nerve to its outer side. Plan of the Relations of the Dorsalis Pedis Artery In Front. Integument, Deep fascia, Inner tendon of extensor brevis digitorum. Inner Side. Tendon of extensor pro- prius hallucis. Outer Side. Tendon of extensor lon- gus digitorum, Border of extensor brevis digitorum, Anterior tibial nerve. Dorsalis Pedis Artery. Behind. Bones and ligaments of the tarsus. Branches.—The branches of this artery are the— Tarsal, Metatarsal, Dorsalis hallucis, Magna hallucis. The tarsal branch arches transversely across the tarsus, beneath the extensor brevis digitorum muscle, and supplies the articulations of the tarsal bones and outer side of the foot; it anastomoses with the external malleolar, peroneal arteries, and external plantar. The metatarsal forms an arch across the base of the metatarsal bones, and supplies the outer side of the foot, anastomosing with the tarsal and external plantar artery. From its convex side the meta- tarsal gives off three branches, dorsal interosseous, which pass forward upon the dorsal interosseous muscles, and divide into branches (dorsal collateral) for the supply of the sides of the toes between which they are placed. At their commencement these interosseous branches receive the posterior perforating arteries from the plantar POSTERIOR TIBIAL ARTERY. arch, and opposite the heads of the metatarsal bones are joined by the anterior perforating branches from the digital arteries. The interosseous artery of the fourth interosseous space, in addition to the two dorsal collateral branches into which it bifurcates, sends a third branch to the outer side of the little toe. The dorsalis hallucis runs forward upon the first dorsal inter- osseous muscle, and at the base of the first phalanx divides into two branches, one of which passes inwards beneath the tendon of the extensor proprius hallucis, and is distributed to the inner border of the great toe, while the other bifurcates into two clorscd collateral digital branches for the adjacent sides of the great and second toe. The arteria magna hallucis arises from the dorsalis pedis, while in the metatarsal space and just before its inosculation with the external plantar artery. It sends a digital branch to the inner border of the great toe on its plantar aspect, and bifurcates to supply the plantar collateral digital branches of the great and second toe. 445 POSTERIOR TIBIAL ARTERY. The posterior tibial artery passes obliquely downwards along the tibial side of the leg from the lower border of the popliteus muscle to the concavity of the os calcis, where it divides into the internal and external plantar artery. In its course it is accompanied by vente comites, and by the posterior tibial nerve, which lies to its inner side at first, and to its outer side for the rest of its course. Plan of the Relations of the Posterior Tibial Artery. Superficially. Integument and fascia, Gastrocnemius, Soleus, Deep fascia, Intermuscular fascia, Posterior tibial nerve. Inner Side. Posterior tibial nerve (upper third), Vein. Posterior Tibial Artery. Outer Side. Posterior tibial nerve (lower two-thirds), Vein. Deeply. Tibialis posticus, Flexor longus digitorum, Tibia, Ankle-joint. Branches.—The branches of the posterior tibia] artery are the— Peroneal, Nutrient, Muscular and cutaneous, Communicating, Internal calcanean, Internal plantar, External plantar. 446 PERONEAL ARTERY. The PERONEAL ARTERY is given oft from the posterior tibial at about an inch below the lower border of the popliteus muscle ; it is nearly as large as the anterior tibial artery, and passes obliquely outwards to the fibula. It then runs downwards along the inner border of the fibula to its lower third, where it divides into the anterior and posterior peroneal. Relations.—The peroneal artery rests on the tibialis posticus muscle, and is covered in by the soleus, intermuscular fascia, and flexor longus hallucis, having the fibula to its outer side. Branches. — The branches of the pero- neal artery are—mus- cular to the soleus and neighbouring muscles; nutrient to the fibula; a communicatimj branch; and two terminal branches, anterior and 'posterior peroneal. The communicating branch is given oft near the lower end of the peroneal; it passes in- wards to join a corre- sponding branch from the posterior tibial. The anterior pero neal artery pierces tin interosseous membrane at the lower third of the leg, and is distri- buted on the front of the outer malleolus, anastomosing with flic external malleolar and tarsal arteries. The posterior pero neal continues onward s along the posterior as- pect of the outer mal- leolus to the side of the os calcis, to which, and to the muscles arising from it, it distributes external calcanean branches. It anas- tomoses with the anterior peroneal, tarsal, external plantar, and posterior tibial arteries. The nutrient artery of the tibia arises from the trunk of the Fig. 271.—Posterior view of the leg, showing the pop- liteal and posterior tibial arteries. 1. Tendons of the inner ham-string. 2. Ten- don of the biceps, forming the outer ham-string. 3. Popliteus muscle. 4. Flex- or longus digitorum. 5. Tibialis posticus. 6. The fibula; immediately below the figure is the origin of the flexor longus hallucis ; the muscle has been re- moved in order to expose the peroneal artery. 7. Peronei muscles, longus and brevis. 8. Lower part of the flexor longus hallu- cis muscle with its tendon. 9. Popliteal artery giving off articular and muscular branches; the two superior articular are seen in the upper part of the popliteal space passing above the two heads of the gastroc- nemius muscle, which are cut through near their origin. The two inferior are in relation with the popliteus musele. 10. An- terior tibial artery passing through the angular inter- space between the two heads of the tibialis posti- cus muscle. 11. Posterior tibial artery. 12. The re- lative position of the ten- dons and artery at the inner ankle from within outwards, previously to their passing beneath the internal annular ligament. 13. Peroneal artery, divid- ing a little below the figure, into two branches; ilie anterior peroneal is seen piercing the interosseous membrane. 14. Pos- terior peroneal. PLATE 25. THE FRONT OF THE LEG AND SOLE OF THE FOOT Fig. 1. A. Tibialis anticus. a, a. Its tendon. B. Extensor longus digitorum. b, b. Its tendons. C. Extensor longus hallucis. c, c. Its tendon. F, F. Peroneus longus. G, G. Peroneus brevis. H, H. Deep fascia covering muscles and fibula. K. Extensor brevis digitorum. L. Anterior tibial artery and nerve. Fig. 2. A. Calcaneum. B. Plantar fascia. C. Abductor minimi digiti. D. Abductor hallucis. E. Flexor accessorius. F. Flexor longus digitorum. G. Flexor longus hallucis. H. Flexor brevis hallucis. i. Lumbricales. L. External plantar artery and nerve. M. Internal plantar artery and nerve. Fig. 3. H. Metatarsal bone of great toe. i. Tendon of tibialis posticus. K. External plantar nerve. L. External plantar artery. M. Interosseous muscles. O. Flexor brevis minimi digiti. P. Tendon of peroneus longus. The other references are the same as in fig. 2. PLATE 25 Fuji Ticj.2 Fi’. Parietal lobe. q. Quadrate lobe. o. Cuneus lobe, t, t. Tem- poral lobe. cm. Calloso-marginal fissure, po. Parietal-occipital fissure, cc. Cal- carine fissure. Co. Collateral fissure. 1, 1. Marginal convolution. 2, 2. Gyrus fornicatus. 3, 3. Uncinate gyrus. 4. Dentate convolution. 5. United corpus callosum and fornix. 6. Genu of corpus callosum. 7. Cavity of lateral ventricle. 8. Fornix. 9. Thalamus with corpora guniculata. 10. Fascia dentata in dentate fissure. winds round the corpus callosum to the posterior part, where it be- comes continuous with the upper internal temporal convolution or uncinate gyrus. It becomes connected in its course with the frontal convolutions, the quadrate lobe, the cuneus, and the lingual lobule. As it winds round the splenium of the cor] ms callosum it bounds the fissure of the hippocampus which forms the hippocampus major ; hence this portion of the gyrus receives the name of gyrus hippocampi. Posterior to the marginal convolution and continuous below with the gyrus fornicatus is the quadrate lobe (precuneus) (q), which is separated from the cuneus lobe (o) by the parieto-occipital fissure (po), a continuation of the fissure of the same name seen externally. STRUCTURE OF THE CONVOLUTIONS. The quadrate lobe or precuneus (q), the inner portion of the parietal lobe, is bounded in front by the calloso-marginal fissure, and behind by the parieto-occipital fissure ; below it is continuous with the gyrus fornicatus, and above with the superior parietal con- volution. The cuneus lobe (o) is triangular in shape, and is placed between the parieto-occipital and the calcarine fissure (c); the latter separates it from the internal convolutions of the temporal lobe (t). The calcarine fissure (c) of Huxley runs below the cuneus lobe to the extremity of the gyrus fornicatus, being joined midway by the parieto-occipital fissure. It is an important fissure, since it corresponds to the projection called the hippocampus minor in the posterior cornu of the lateral ventricle. The internal temporal convolutions form the lower part of the inner wall of the hemisphere, and are continuous with those of the temporal lobe externally. The most important is the uncinate gyrus (3), which is immediately below the calcarine fissure and runs horizontally forward, becoming united with the gyrus fornicatus and passing in front of the fascia dentata. It then makes a sudden bend backward for half an inch, this hook-like process from which it derives its name becoming united with the taenia hippo- campi. The collateral fissure (Co) separates this last convolution from the inferior temporal convolutions, which are very irregular. It causes the prominence in the descending cornu of the lateral ven- tricle known as the eminentia collateralis. The dentate fissure (10) is that immediately above the unci- nate gyrus which lodges the fascia dentata, and corresponds to the hippocampus major in the descending cornu of the lateral ven- tricle. Immediately above this is a small dentate convolution (4), united with the tenia hippocampi, and continuous below with the uncinate gyrus. Structure of the Convolutions. The convolutions are composed internally of white nerve matter continuous with that which forms the great hulk of the interior of the brain; externally they are covered by several superimposed layers of grey matter, each layer having certain characteristics which serve to distinguish it from its fellows. The layers vary in their number and depth in different brains and in different parts of the same brain, but in the parietal lobe it is easy with the microscope to distinguish that they are five in number. The first or external layer forms about one-tenth of the thick- ness of the cortex. It is pale in colour, and consists chiefly of neuroglia, in which a few scattered stellate nerve-cells are found, and near the surface numerous fine varicose medullated nerve- fibres, crossing each other in all directions. The second layer, of about the same width, is made up of closely set small pyramidal nerve-cells with branching processes, the apex 506 CEREBRUM. of the pyramid being a little drawn out, and in every instance directed towards the surface of the convolution. The third layer is wider and paler than the second ; it consists of large pyramidal cells separated into groups by the radiating fibres of the hemisphere. The fourth layer is composed of small, closely set, angular corpuscles, placed ir- regularly, and imperfectly separated into groups. The fifth is a layer of fusiform cor- puscles which are placed vertically to the summit of a gyrus, but parallel to the surface of a sulcus. With the unaided eye it is easy to note the alternation of whitish with reddish- grey layers, hut it is at all times difficult, even with the microscope, to ascertain the number of layers, or to define accurately the limits of each. The Interior of the Cerebrum. If the brain be placed upon its base, and the upper part of one hemisphere, at about one-third from its summit, be re- moved with a scalpel, a centre of white substance will be observed, surrounded by a narrow border of grey, which follows the line of the sulci and convolutions, and presents a zigzag form. This section is called centrum ovale minus; it is spotted by numerous small red points (puncta vasculosa), which are produced by the escape of blood from the cut ends of minute arteries and veins. Separate carefully the two hemispheres of the cerebrum, and a broad band of white substance (corpus callosum) will be seen to connect them ; it will be seen also that the surface of the hemisphere, where it comes in contact with the corpus callosum, is bounded by the gyrus fornicatus. The sulcus between this convolution and the corpus callosum has been termed the “ven- tricle of the corpus callosum.” If the upper part of each hemisphere be removed to a level with the corpus callosum, a large expanse of medullary matter, surrounded by a zigzag line of grey substance corresponding with the convolutions and sulci of the two hemi- spheres, will be seen ; this is the centrum ovale majus of Yieussens. The corpus callosum is a thick layer of fibres passing trans- versely between the two hemispheres, and constituting their great Fig. 302.— Section of grey cortex of a convolution. 1, 2, 3, 4, 5. The five layers described in the next. m. The white centre of the brain. CORPUS CALLOSUM. commissure. It is situated in the middle line of the centrum ovale majus, but nearer the anterior than the posterior part of the brain, and ends anteriorly in a rounded border, genu, which may be traced downwards to the base of the brain in front of the commissure of the optic nerves ; it here gives off two narrow white hands called _'peduncles, which diverge from each other and pass backwards across the substantia perforata to the fissure of Sylvius, where they terminate. Posteriorly it forms a thick rounded fold, splenium, which is connected on its under surface with the fornix ; throughout the rest of its extent the corpus callosum is con- nected on its under sur- face with the septum luci- dum. The length of the corpus callosum is about four inches. Along the middle line is the raphe', a linear depression between two slightly elevated longi- tudinal hands (chordae lon- git udinales Lancisii); and, on each side of the raphe', may be seen the linece transversce, which mark the direction of the fibres of which the corpus callosum is composed. These fibres may be traced into the hemispheres on each side, and they will be seen to be crossed at about an inch from the raphe', by lateral longitudinal fibres, strife longitudinales laterales. Anteriorly and posteriorly the fibres of the corpus callosum curve forwards and backwards into their corresponding lobes. Beneath the posterior rounded border of the corpus callosum is the transverse fissure of the cerebrum, which extends between the hemispheres and crura cerebri from near the fissure of Sylvius on one side, to the same point on the opposite side of the brain. It is through this fissure that the pia mater communicates with the velum interpositum. If a superficial incision be made through the corpus callosum on each side of the raphe', two irregular cavities will be opened, which extend from one extremity of the hemispheres to the other; these Pig. 303.—Section of the brain showing the cen- trum ovale majus and corpus callosum. 1, 1. Frontal lobes of the brain. 2, 2. Occipital lobes. 3, 3. Longitudinal fissure for the reception of the falx cerebri. 4, 4. Roof of the lateral ven- tricles. 5, 5. Genu of the corpus callosum. 6. Its body, upon which the lineal transversal are seen. 7, 7. Splenium. 8. Raphfi. 9, 9. Striai longitudinales latei’ales. 508 CEREBRUM. are the lateral ventricles. To expose them completely, their upper boundary should be removed with the scissors. In making this dis- section the thin and diaphanous lining membrane of the ventricles may frequently be seen. LATERAL VENTRICLES.—Each lateral ventricle is divided into a central cavity and three smaller cavities called cornua. The ante- rior cornu curves forwards and outwards in the anterior lobe ; the middle cornu descends into the middle lohe ; and the posterior cornu passes backwards in the posterior lobe, converging towards its fellow of the opposite side. The central cavity is triangular in form, being bounded above (roof) by the corpus callosum ; internally by the septum lucidum, which separates it from the opposite ven- tricle ; and below (floor) by the following parts, taken in their order of position from before backwards :— Corpus striatum, Teuia semicircularis, Thalamus opticus, Choroid plexus, Corpus fimbriatum, Fornix. The corpus striatum is named from the striated lines of white and grey matter which are seen upon cutting into its substance. The portion of it which is seen in the lateral ventricle is the intra- ventricular nucleus or nucleus caudatus. Its anterior extremity forms a rounded projection in the anterior cornu ; from whence it may be traced outwards and backwards, along the outer border of the optic thalamus, and separated from it by the stria terminalis. It becomes much narrower as we trace it backwards (the appearance thus pro- duced giving rise to the name of nucleus caudatus), and its extremity will be found in the roof of the middle or descending horn. The other parts of the corpus striatum will lie described when the structures seen in a transverse section of the brain are under con- sideration. The taenia semicircularis or stria terminalis is a narrow whitish band, extending along the posterior border of the corpus striatum, and serving as a bond of connection between that body and the thalamus opticus. It joins the anterior pillar of the fornix and is continued with it to the corpora albicantia. The tenia is partly con- cealed by a large vein (vena corporis striati), which receives numerous small veins from the corpus striatum and thalamus opticus, and terminates in the vena Galeni of its own side. The thalamus opticus (thalamus, a bed) is an oblong body, having a thin coating of white substance on its surface; and has received its name from having the optic tract lying against its under surface. It is the inferior ganglion of the cerebrum. Part only of the thalamus is seen in the floor of the lateral ventricle ; we must, therefore, defer its further description until we can examine it in its entire extent. The choroid plexus (yoptoi/, fiSoy, resembling the chorion) is a vascular fringe extending obliquely across the floor of the lateral ventricle, and sinking into the middle cornu. Anteriorly, it is small and tapering, and communicates with the choroid plexus of the opposite ventricle, through a large oval opening, the foramen of Monro, or foramen commune anterius. This foramen may be seen by pulling slightly on the plexus, and pressing aside the septum lucidum with the handle of the knife. It is situated between the under surface of the fornix and the anterior extremities of the thalami optici, and forms a communication transversely between the lateral ventricles, and perpendicularly with the third ventricle. The choroid plexus presents on its surface a number of minute vascular processes, which are termed villi. They are covered by an epithelium consisting of a single layer of nucleated polygonal LATERAL VENTRICLES. 509 Fig. 304.—Lateral ventricles of the cerebrum. 1, 1. The two hemispheres cut down to a level with the corpus callo- sum so as to constitute the centrum ovale majus. 2. Genu of the corpus callosum. 3. Splenium ; the interme- diate portion forming the roof of the lateral ventricles has been removed. 4. Part of the septum lucidum, showing an interspace be- tween its layers, the fifth ventricle. 5. Anterior cornu of one side. 6. Commence- ment of the middle cornu. 7. Posterior cornu. 8. Inter- ventricular nucleus of cor- pus striatum. 9. Tenia semi- eircularis. 10. Thalamus op- ticus. 11. Choroid plexus. This plexus communicates with that of the opposite ventricle through the fora- men of Monro; a bristle is passed through this opening (under figure 4), and its ex- tremities are seen resting on the corpus striatum at each side. The figure 11 rests on the edge of the fornix, on that part of it which is called corpus fimbriatum. 12. ; Fornix. 13. Commencement of the hippocampus major. The rounded oblong body, directly behind figure 13, is the pes accessorius, and farther back, imme- 1 diately under figure 7, the hippocampus minor. cells, which are ciliated in the embryo, but the cilia are absent in the adult. Besides the nucleus the cells contain numerous yellow granules and one or two dark oil-drops ; and, according to Henle, give off from their angles spine-like processes, which are connected with the bed of homogeneous areolar tissue on which they rest. The chief arteries of the choroid plexuses enter at the lower ex- tremity of the middle horn of the lateral ventricle ; others enter it from behind by passing beneath the splenium of the corpus callosum; the veins terminate in the veins of Galen. The corpus fimbriatum is a narrow white band, situated inter- nally to the choroid plexus, and extending with it into the descend- ing cornu of the lateral ventricle. It is, in fact, the lateral thin CEREBRUM. edge of the fornix, and being attached to the hippocampus major in the descending horn of the lateral ventricle, is also termed taenia hippocampi. The fornix is a white layer of medullary substance, of which a portion only is seen in this view of the ventricle. The anterior cornu is triangular in form, sweeping outwards and terminating by a point in the anterior lobe of the brain, at a short distance from its surface. It has projecting into its cavity the nucleus caudatus of the corpus striatum. The posterior cornu curves inwards, as it extends back into the posterior lobe of the brain and likewise terminates near the surface. An elevation corresponding with the calcarine fissure on the inner surface of the hemisphere, projects into the area of this cornu, and is called the hippocampus minor or calcar avis. The middle or descending cornu, in descending into the middle lobe of the brain, forms a very considerable curve, and alters its direction several times as it proceeds. Hence it is described as passing backwards and outwards and downwards, and then turning forwards and inwards. This complex expression of a very simple curve has given origin to a symbol, formed of the primary letters of the term, by which the student is enabled to recollect more easily the course of the cornu, bodfi. It is the largest of the three cornua, and terminates close to the fissure of Sylvius, after having curved around the crus cerebri. The middle cornu should now be laid open by inserting the little finger into its cavity, and making it serve as a director for the scalpel in cutting away the side of the hemisphere, so as to expose it completely. The superior boundary of the middle cornu is formed by the fibres of the corpus callosum, as they arch downwards to reach the temporo-sphenoidal lobe ; with these the tail of the nucleus caudatus and the fibres of the taenia semicircularis are united. The inferior wall presents for examination the following parts ::— Hippocampus major, Pes hippocampi, Pes accessorius, Corpus fimbriatum, Choroid plexus, Fascia dentata, Transverse fissure. The hippocampus major or cornu ammonis is a considerable projection from the inferior wall, and extends the whole length of the middle cornu. Its extremity is likened to the foot of an animal, from its presenting a number of knuckle-like elevations on the sur- face, and is named pes hippocampi. The hippocampus major corre- sponds to the sulcus on the inner side of the gyrus fornicatus, as that convolution winds round beneath the splenium of the corpus callosum to end in the uncinate gyrus. If the hippocampus be cut across, the section will be seen to resemble the extremity of a convoluted scroll, consisting of alternate layers of white and grey substance. TRANSVERSE FISSURE. The pes accessorius (eininentia collaterals) is a swelling some- what resembling the hippocampus major, but smaller in size, and situated in the angular interval between it and the hippocampus minor. It is formed by the protrusion of the sulcus described above as the collateral fissure. The corpus fimbriatum (taenia hip- pocampi) is the thinned and flattened posterior pillar of the fornix, which is prolonged from the central cavity of the ventricle, and is attached along the inner border of the hippocampus major. It is lost inferiorly in the hippocampus. Fascia Dentata. — If the corpus fimbriatum be carefully raised, a nar- row serrated band of grey substance, the margin of the grey substance of the middle lobe, will be seen beneath it; this is the fascia dentata. It is so called from presenting an appear- ance resembling a regular row of teeth. Transverse Fissure.—Beneath the corpus fimbriatum will be seen the transverse fissure of the brain, which extends from near the fissure of Sylvius on one side, across to the same point on the opposite side. It is through this fissure that the pia mater com- municates with the choroid plexus, and the latter obtains its supply of blood. The fissure is bounded above by the corpus callosum and fornix in the middle, and on each side by a free margin of the hemisphere formed by the fascia dentata and corpus fimbriatum ; inferiorly, it is bounded near the middle line by the corpus quadri- gernina, and on each side by the back part of the optic thalamus. In its central part it lodges the velum interpositum. Septum Lucidum.—The internal boundary of the lateral ven- tricle is the septum lucidum. This septum is thin, semi-transparent, and consists of two laminae of cerebral substance attached above to the under surface of the corpus callosum at its anterior part, and below to the fornix. Each of these laminae consists of white and grey matter, the white being situated on the surface looking towards the lateral ventricle, the grey matter nearer the middle line of the brain. Between the two layers is a narrow space, the fifth ven- tricle, which is lined by a proper membrane. The fifth ventricle may be shown by snipping through the septum lucidum transversely with the scissors. The corpus callosum should now be cut across towards its an- terior extremity, and the two ends carefully dissected away. The anterior portion will be retained only by the septum lucidum, but Fig. 305.—Section through the hippocampus major, showing fascia dentata. 1. Pes hippo- campi. 2. Corpus fimbriatum. 3. Fascia dentata. 4, 4. Hippo- campal gyrus. 5. Uncinate gyrus. 6. Section through the hippocampus. 512 CEREBRUM. the posterior will be found incorporated with the white layer be- neath, which is the fornix. Fornix.—The fornix (arch) is an arched band of white substance, placed in the floor of the lateral ventricle, and intimately connected posteriorly with the under surface of the corpus callosum. It con- sists of two lateral halves which unite in the middle of the lateral ventricle forming the body, but diverge from each other posteriorly as the posterior pillars or crura, and anteriorly as the anterior pillars or crura. The two anterior crura descend in a curved direction to the base of the brain, embedded in the anterior part of the Fig. 306.—Vertical longitudinal section of the brain. 1. Marginal convolution. 2. Gyrus fornicatus. 3. Velum interpositum. 4. Corpus callosum. 5. Peduncle of pineal gland on the margin of optic thalamus. 6. Septum lucidum. 7. Middle commissure of third ventricle. 8. Fornix. 9. Pineal body. 10. Foramen of Monro. 11. Transverse fissure. 12. Anterior commissure. 13. Corpora quadri- gemina. 14. Posterior commissure. 15. Valve of Vieussens. 16. Aqueduct of Sylvius. 17. Fourth ventricle. 18. Optic nerve. 19. Arbor vita; cerebelli. 20. Pituitary body and infundibulum. 2r. Section of medulla. 22. Corpus albican- tium. 24. Locus perforatus posticus. 26. Section of pons. septum lucidum, and lying directly behind the anterior com- missure. At the base of the brain they make a sudden curve upon themselves and constitute the corpora alhicantia, from which they may be traced upwards to the thalami optici. Opening trans- versely beneath these two crura, just as they are about to arch down- wards, is the foramen of communication between the lateral and the third ventricle, the foramen of Monro ; or foramen commune anterius. The choroid plexuses and the veins of the corpora striata pass through this opening. The lateral thin edges of the fornix are continuous posteriorly with the concave border of the hippocampus major at each side, THALAMI OPTICI. and form the narrow white hand called corpus fimbriatum or tcenia hippocampi. In the middle line the fornix lies in contact by its upper surface with the corpus callosum, and by its under surface with the velum interpositum. The fornix may now he removed by dividing it across anteriorly, and turning it backwards, at the same time separating its lateral connections with the hippocampi. On examining its under surface it will be noticed that where the posterior pillars diverge from each other they expose the fibres of the corpus callosum, and that these are for the most part transverse. The appearance presented by the lateral bars formed by the fornix and the transverse lines of the corpus callosum, has been named the lyra from a fancied resem- blance to a harp. Velum Interpositum.—Beneath the fornix is the velum inter- positum (tela choroidea), a fold of pia mater introduced into the interior of the brain through the transverse fissure. It extends from the foramen of Monro in front to the back part of the splenium of the corpus callosum behind ; laterally, it passes beneath the edge of the fornix and reaches the floor of the lateral ventricles, where it is connected with the choroid plexuses of those cavities. In this way it gives to the edge of the fornix that fringed appearance from which its name of corpus fimbriatum has been derived. On its under surface the velum forms the roof of the third ventricle, having attached to it the choroid plexuses of the latter cavity ; and at the back part it is intimately connected with the pineal body. In the centre of its upper aspect run two veins, the veins of Galen, which receive blood from the interior of the ventricles, and empty it into the straight sinus. The velum interpositum is coated with an epithelium identical with that of the choroid plexuses ; and around the pineal body the areolar tissue is abundant and strong. If the velum interpositum be raised and turned back, an opera- tion to be conducted with care, particularly at its posterior part, where it invests the pineal body, the thalami optici and the cavity of the third ventricle will be brought into view. Thalami Optici.—The thalami optici are two oval bodies, of a white colour superficially, inserted between the two diverging portions of the corpora striata, and resting upon the upper surface of the crura cerebri. In the middle line a fissure exists between them which is called the third ventricle. The anterior part forms a rounded prominence immediately behind the tamia seinicircularis, and is called the anterior tubercle; the posterior extremity forms a free rounded border, projecting into the transverse fissure of the brain, the posterior tubercle or pulvinar. Beneath the latter lie two small rounded elevations, the external and internal geniculate bodies, separated from each other by one of the roots of the optic nerve. The corpus geniculatum externum, the larger of the two, and of a greyish colour, is the principal origin of the optic nerve. The upper surface of the optic thalamus is marked by a shallow groove, which distinguishes the limit of the floor of the lateral ventricle ; and CEREBRUM. at tlie junction of the internal and upper surfaces a band of white fibres will he noticed constituting the peduncle of the pineal body. Between the upper edge of the pulvinar and the peduncle of the pineal body is a triangular depression called trigonum habcnulce. Anteriorly, the tlialami are connected with the corpora albicantia by means of two white bands, which are the terminations of the crura of the fornix. Externally, they are in relation with the corpora striata and hemispheres. In their interior the tlialami are chiefly composed of grey matter arranged in three masses, the anterior, ex- ternal, and internal nuclei. Third Ventricle.—The third ventricle is the fissure between the two tlialami optici, and is the remains of the anterior cerebral vesicle. It is bounded above by the under surface of the velum interpositum, from which are suspended the choroid plexuses of the third ven- tricle, and is separated by the velum from the body of the fornix. Its floor is formed by the lamina cinerea, the tuber cinereum, infundibulum, corpora albicantia, and locus perforatus posticus. Laterally, it is bounded by the tlialami optici and peduncles of the pineal body ; anteriorly, by the anterior commissure and anterior crura of the fornix ; and posteriorly, by the posterior commissure and the aqueduct of Sylvius. The third ventricle is crossed by three commissures, anterior, middle, and posterior ; and communicates by two openings, called foramen of Monro and aqueduct of Sylvius, with the lateral and fourth ventricles. The anterior commissure is a small rounded white cord, which connects the corpora striata of the two sides, and reaches the sub- stance of the hemispheres ; it lies immediately in front of the crura of the fornix, and is united by its anterior margin with the septum lucidum. The middle or soft commissure consists of grey sub- stance, which is continuous with the grey lining of the ventricle ; it connects the adjacent sides of the tlialami optici. The posterior commissure, smaller than the anterior, is a flattened white cord, connecting the two tlialami optici posteriorly ; it is placed beneath the peduncles of the pineal body near their origin, and has beneath it the aqueduct of Sylvius. The foramen of Monro is the medium of communication be- tween the two lateral and third ventricles, and transmits superiorly the choroid plexus and veins of the corpus striatum. The aqueduct of Sylvius, or iter a tertio ad quartum, ventriculum, leads backwards beneath the posterior commissure and through the base of the corpora quadrigemina to the upper part of the fourth ventricle. Corpora Quadrigemina.—The corpora quadrigemina, or optic lobes, are situated immediately behind the third ventricle and pos- terior commissure, and beneath the posterior border of the corpus callosum. They form, indeed, at this point, the inferior boundary of the transverse fissure of the hemispheres. The anterior pair of these bodies, grey in colour, are named nates; the posterior pair, white and much smaller than the anterior, are termed testes. From the nates on each side may be traced a rounded process (bracliium superior) which passes obliquely outwards into the thalamus opticus ; and from the testis a similar but smaller process (bracliium inferior) which has the same destination. The internal geniculate body lies in the interval of these two processes where they enter the thalamus, and behind the inferior bracliium is a prominent band which marks the course of the superior division of the olivary fasci- culus. The corpora quadrigemina are perforated longitudinally through their base by the aqueduct of Sylvius ; they are covered in partly by the pia mater and partly by the velum interpositum, and the nates support the pineal body. Two large white hands pass PINEAL BODY. Fig. 307.—Third ven- tricle of brain. 1. Corpus striatum dis- sected. 2. Fifth ven- tricle. 3. Anterior crura of fornix (cut). 4. Corpus striatum. 5. Anterior commis- sure of third ven- tricle. 6. Optic tha- lamus. 7. Middle or soft commissure. 8. Peduncles of pineal body. 9. Third ven- tricle. 10. Pineal body. 11. Ttenia semicircularis. 12. Corpora quadrige- mina. 13. Valve of Vieussens. 14. Fourth ventricle. 15. An- terior extiemity of superior vermiform process. 16. Arbor vitae cerebelli. 17. Anterior extremity of inferior vermiform process (nodulus). 19. Communication of fourth ventricle with sub-arachnoid space. clown from them to the cerebellum, forming the 'processus e cerebello ad testes, the great bond of connection between the great and little brain. Pineal Body.—The pineal body (epiphysis cerebri) is a small reddish-grey body of a conical form (hence its synonym conarium), situated on the anterior part of the nates, and invested by a duplica- ture of pia mater derived from the under part of the velum inter- positum. It is connected to the brain by means of two cords of white matter called peduncles, which may be traced along the upper and inner margin of the tlialami optici to the crura of the fornix with which they become blended. From the close connection sub- sisting between the pia mater and the pineal body, and the softness of texture of the latter, it is liable to be torn away in the removal of the pia mater. CEREBELLUM. The cerebellum, less than one-eighth the weight of the cerebrum, is situated beneath the occipital lobes, being lodged in the posterior fossa of the base of the cranium, and protected from the superin- cumbent pressure of the cerebrum by the tentorium cerebelli. Like the cerebrum, it is composed of grey and white substance, the former occupying the surface, the latter the interior, and its surface is formed of parallel lamella) separated by sulci, and here and there by deeper sulci. In form, the cerebellum is oblong and flattened, its greater diameter being from side to side, its two surfaces looking upwards and downwards, and its borders being anterior, posterior, and lateral. In consideration of its shape the cerebellum admits of a division into two hemispheres, into certain prominences termed processes and lobules, and into certain divisions of its substance called lobes, formed upon the hemispheres by the deeper sulci above referred to. On the anterior border of the organ there is a semilunar notch, incisura cerebelli anterior, which embraces the corpora quadrigemina. On the posterior border there is another notch, incisura cerebelli posterior, which receives the upper part of the falx cerebelli; and on the under surface of the cerebellum is a deep fissure corre- sponding with the medulla oblongata, and termed the val- lecula (valley). Each hemisphere of the cerebellum is divided by means of a fissure which runs along its free border into an upper and a lower portion, and upon each of these portions cer- 1 ai n lobes are marked out. Thus on the upper portion there are two such lobes, the anterior superior or quadrate lobe, and the posterior superior lobe. On the under portion of the hemisphere there are three such lobes, namely, the posterior inferior lobe, the slender (gracilis) lobe, and the biventral lobe ; and two smaller ones, the tonsil (amygdala), situated at the side of the vallecula, and the flocculus (pneumogastric lobe), placed behind and below the middle peduncle of the cerebellum. The central mass connecting the two hemispheres is called the worm, (vermis) ; its upper aspect projects above the general level of CEREBELLUM. Fig. 308.—Under surface of cerebellum, the amygdala; having been removed. 1. Medulla oblongata. 2. Pons Varolii. 3. Choroid plexus of the fourth ventricle. 4. Flocculus. 5. Biventral lobe of cerebellum. 6. Nodulus of inferior vermiform process. 7. Uvula. 8.. Posterior medullary velum. 9. Pyramid. 10. Slender lobe. 11. Posterior inferior lobe. LOBES OF THE CEREBELLUM. the cerebellum, and is called the superior vermiform process ; the lower part is lodged within the vallecula, and is named the inferior vermiform process. The superior vermiform process is very indis- tinctly demarcated from the upper surface of the hemispheres, the folia of the latter being continued into it; at its anterior border, about eight folia form the central lobe, a portion of which is con- tinued upwards on to the superior medullary velum or valve of Yieussens, and is termed, from its shape, the lingula. The posterior superior lobe is only represented in the superior vermiform process by a single well-marked lamina, the folia cacuminis. The inferior vermiform process is divisible into four lobes, namely: (i) the tuber vallce situated in the incisura posterior, and connecting the postero- inferior and slender lobes of the two sides ; (2) in front of this the pyramid, a small, obtusely pointed eminence connecting the biventral lobes ; (3) the uvula, placed between the two tonsils; and (4) the nodule or laminated tubercle, forming a free pointed anterior termi- nation to the process. Connecting the uvula on each side with the tonsil is a ridge of grey matter, the f urrowed band. On each side of the nodule is a thin layer of white matter, the posterior medullary velum; it has a membranous texture, and terminates anteriorly in a crescentic border; laterally, each process can he traced into the flocculus. Between the posterior velum and the nodule and uvula is a deep fossa which is known as the swallow’s nest (nidus hirundinis). The anterior medullary velum is the valve of Vieussens, which will he described in connection with the fourth ventricle. The cerebellum is connected with the rest of the encephalon by means of three pairs of rounded cords or peduncles, superior, middle, and inferior. The superior peduncle (processus e cerebello ad testes) forms the superior lateral boundary of the fourth ventricle, and is continued upwards and forwards upon the upper surface of the crus cerebri to the corpora quadrigemina, beneath which its fibres decus- sate with those of the corresponding process of the opposite side ; higher up they may be traced into the white centre of the hemi- sphere. The middle peduncle (processus ad pontem) connects the two hemispheres of the cerebellum, and is constituted by the transverse fibres of the pons. The inferior peduncle, (processus ad medullam) is the connection of the cerebellum with the medulla and spinal cord, and has been already described under the title of resti- form body or tract. The three peduncles together form the crus cerebelli of each side. Structure of the Cerebellum.—-A horizontal section of the cerebellum shows it to be composed, like the cerebrum, of an internal white mass, and of grey cortical matter; but the grey mattei greatly preponderates, so that the white centre is relatively small The white substance resembles the trunk of a tree, from which branches are given off, and from the branches, branchlets and leaves the two latter being coated by a moderately thick and uniform layer of grey substance. The appearance thus produced has received the name of arbor vitce cerebellce. I11 each lateral half of the white CEREBELLUM. centre will be seen an irregular mass of grey matter, forming a wavy line, and enclosing white matter ; this is the corpus dentatum. It exists as a grey capsule or pouch, which, however, is defective at its inner part. If the section be made rather nearer to the under surface of the cere- bellum than its centre, other nuclei will be displayed in the white centre. These are three in number on each side, and are named the nucleus fas- tigii, nucleus globosus, and nucleus emboliformis (Fig. 309). The nucleus fastigii is situated near the middle line ; it is rounded in front, but behind becomes forked. The nuclei globosi generally con- sists of two or three round grey spots a little external to the preceding. The nucleus emboliformis is a club-shaped mass of grey matter running antero-posteriorly close to the inner side of the corpus den- tatum. Minute Structure. — The grey cortex is divisible into two layers, the outer being of a clear grey colour, and the inner rust- coloured and granular in ap- pearance. The external layer consists of a delicate neuroglia supporting nerve-fibres and nerve-cells ; the fibres run for the most part at right angles to the surface of the cerebellum, and many of them are connected with the processes of the cells below; the cells are very small, and have the appearance of granules. Tin; inner layer is formed also of granule-like cells very closely aggregated, and embedded in a gelatinous matrix. Between the inner and outer layers is a single layer of peculiar cells called cells of Purkinje; they are chiefly flask-shaped, and give off from their deep aspect a single process which becomes connected with the axis-cylinder of a nerve in the white centre ; from its super- ficial surface each cell gives off two processes which branch very freely in an antler-like, manner, some of their finer processes becoming connected with the round cells of the outer layer. The Fig. 309.—Part of the white centre of the cerebellum, showing the nuclear masses. li. Lingula, c. Commissural fibres. a. Nucleus fastigii. g, g1, and <72. Nuclei globosi. e. Nucleus emboliformis. rf. Corpus dentatum. v.i. Inferior vermi- form process, a.v. Arbor vital cerebelli. FOURTH VENTRICLE. white centre is composed of medullated nerve-libres, some of which are (i) commissural between the two hemispheres of the cerebellum, others (2) are association fibres between different folia, and (3) other fibres spring from the central nuclei above described. Fourth Ventricle. Dissection. — An oblique incision must be made through each half of the cerebellum, and the wedge-shaped intervening mass removed ; the mem- branes covering the back part of the medulla and pons must be carefully cleared away, when the fourth ventricle will be displayed. The fourth ventricle is the remains of the posterior cerebral vesicle of the embryo, and is situated between the cerebellum and the posterior surface of the medulla and pons; it is diamond- shaped, with narrow angles directed upwards and downwards, and wider angles passing towards each crus cere- belli (lateral recesses). The lower angle is called the calamus scriptorius, from a fancied resemblance to Fig. 310.—-1 a. External and, ib, Internal portions of the outer grey layer. 2. Layer of cells of Purkinje. 3. Inner layer. m. Medullary layer. Fig. 31 i.—1. Median groove of the fourth ventricle, with the fasciculi teretes, one on each side. 2. The striae acusticse and origin of the audi- tory nerve. 3. Tho restiform body. 4. The pos- terior pyramid ; the figure is placed on the right clava. 5. The processus e cerebello ad tes- tes. 6. The cor- pora quadri- gemina. the nib of a pen ; it is marked by a slight pit, the ventricle of Aranzi, which communicates with the central canal of the spinal 520 FOURTH VENTRICLE. cord. The upper angle has opening into it the aqueduct of Sylvius, by which the fourth ventricle communicates with the third. The roof is tent-shaped, and is formed by a thin layer of grey matter connecting the upper part of the two processus e cerebello ad testes, called the valve of Vieussens (velum medullare anterius), by the anterior medullary velum, the nodule of the inferior vermiform process, and the pia mater passing from the latter to the medulla. A thickening of the epithelium on the under surface of the pia mater at the lower angle of the cavity gives rise to a process called the obex, and a similar thickening running along the side wall from the obex to the lateral recess is called the ligula (Fig. 312, l.). The floor has running down its centre a slight groove continuous with the posterior median fissure of the cord, and, crossing its middle, some trans- verse lines, the strice acusticce. These lines mark the superior limit of the medulla ; they also serve to divide the floor of the ventricle into two tri- angles, the upper belonging to the medulla, and the lower to the pons. These are again divided vertically by the median fissure, and each of the four divisions so formed is marked by a triangular depression or fovea. The division formed by the medulla may be defined as consisting of (1) the depres- sion of the inferior fovea; (2) a ridge between it and the median Assure, the fasciculus teres; (3) a pro- minence between the fovea and the lateral wall, the tuberculum acusticum; and (4) a grey mass between the fovea and the inferior angle, the ala cinerea. In like manner the area belonging to the pons consists of: (1) the superior fovea, (2) the upper part of the fasciculus teres, and (3) a pigmented area between the superior fovea and the lateral wall, the locus cerulcus. The lateral boundaries of the ventricle are : in the upper part, the two processus e cerebello ad testes; in the lower, the funiculi qraciles with their clavce; above these the funiculi cuneati, and still higher up the restiform bodies. The roof of the fourth ventricle has been already described as partly formed by pia mater covered by epithelium. In the part so formed there is a small opening, the foramen of Magendie, placed a little above the calamus scriptorius, by means of which the cavity of the ventricle communicates with the posterior sub-arachnoid space ; other openings also exist in each lateral recess. In the floor of the fourth ventricle are placed the nuclei of origin of the chief cranial nerves, as well as the vaso-motor, cardiac, and respiratory centres. The nucleus of the hypoglossal nerve lies be- neath the fasciculus teres. In the lower part of the ala cinerea is situated the nucleus of the spinal accessory nerve ; in its upper part the nuclei of the vagus and glosso-pharyngeal nerves, the latter being Fio. 312. — Dia- grammatic view of the floor of the fourth ven- tricle. 111. a. Mesial sulcus. s.f. Superior fo- vea. l.r. Late- ral recess, str. Striseacusticse. if. Inferior fo- vea. t. a. Tuber- culum acusti- cum. a.c. Ala cinerea. 1. Ligula. (E. A. Schafer.) NERVE NUCLEI IN FOURTH VENTRICLE. 521 placed above the former. Close to the lateral recesses in the upper portion of the floor are the sensory (outer) and motor (inner) nuclei of the fifth nerve ; higher up and nearer the middle line is the nucleus of the sixth nerve ; deeper down, between the fifth and sixth is the centre for the seventh nerve. The nuclei of the Fig. 313.—Floor of fourth ventricle, showing nu- clei of origin of cranial nerves, a. Pineal body. 6. Pulvinar of optic thalamus, c. Anterior corpus quadrigeminus (nates). d. Posterior corpus quadrigeminus (testes). e. Anterior brachium. /. Posterior brachium. g. Internal geniculate body. h. Crus cerebri, i. Middle peduncle of crus cere- belli. k. Superior pe- duncle (processus e cerebello ad testes). 1. Inferior peduncle (res- tiform). m. Locus ce- ruloeus. n. Eminentia teres. o. Obex. p. Funiculus gracilis, r. Funiculus cuneatus. s. Funiculus of Rolando. t. Fasciculus teres. The nuclei of the cranial nerves are indicated by italic figures, the nerve trunks by Roman nu- merals. eighth or auditory nerve are covered by the tuberculum acusticum and transverse striae. The position of these nuclei will be best understood by reference to Fig. 313. Transverse Section of the Cerebrum. Transverse vertical sections of tlie cerebrum at different levels are useful for the purpose of ascertaining the relative position of the structures in the interior, and more especially for determining the relation which the two great basal ganglia, the thalamus opticus and corpus striatum, bear to each other and to surrounding parts. The figure here given (Fig. 314) is taken from a recent section of the 522 brain, which has been made immediately behind the corpora albi- cantia ; it passes through the lateral and third ventricles, the middle horn of the lateral ventricles, island of Reil, thalamus opticus, fornix, and corpus striatum. The latter is now seen to be a composite body made up of several independent nuclei ; its full description is as follows. The corpora striata are two pyriform bodies placed with their broad ends forwards and their narrow ends backwards. They are throughout the greater part of their extent embedded in the sub- TRANSVERSE SECTION OF CEREBRUM. Fig. 314.—Transverse vertical section of the cerebrum made immediately behind the corpora albicantia. 1. Longitudinal fissure. 2. Corpus callosum. 3. Fornix. 4. Island of Reil, 5. Nucleus caudatus. 6. Internal capsule. 7. External capsule. 8. Tenia- form nucleus or claustrum. 9. Lenticular nucleus. 5, 6, 7, 8, and 9 together con- stitute the corpus striatum. 10. Thalamus opticus, n. Third ventricle. 12. Crus cerebri. 13. Corpora albicantia. 14. Tuber cinereum and commencement of in- fundibulum. 15. Optic tract. 16. Extremity of middle horn of lateral ventricle. stance of tlie hemispheres, hut their anterior extremities come to the surface in the body and anterior horn of the lateral ventricles ; they are thus divisible into an intraventricular and an extraven- tricular portion. The intraventricular portion is named nucleus caudatus ; its large end, or head, is directed forwards and projects into the anterior cornu of the lateral ventricle ; its smaller end or tail runs on the outer side of the thalamus, and narrowing as it pro- ceeds backwards, terminates by a pointed end in the roof of the descending horn. The extraventricular portion lies to the outer side of the optic thalamus, and between it and the island of Reil; CRURA CEREBRI. 523 it is chiefly formed by a large nucleus, which on horizontal section presents the appearance of a biconvex lens ; hence it has been named the lenticular nucleus. I11 a transverse vertical section this nucleus appears triangular, with the base directed outwards and the apex inwards; the grey matter which forms its bulk is streaked by numerous white fibres which radiate as they pass through it into the convolutions. On the inner side the lenticular nucleus is separated from the nucleus caudatus and thalamus opticus by a strand of white matter called the internal capsule, and on the outer side a similar but less-marked band called external capsule lies be- tween it and the island of Reil ; a grey streak in the middle of the latter has been named the teniaform nucleus or claustrum. Transverse Section of the Crura Cerebri. The crura cerehri or cerebral peduncles are two rounded white masses which proceed from the upper margin of the pons, and, .diverging from each other, enter the under aspect of the hemi- spheres in the region of the basal ganglia. In front of the diverging crura is the posterior perforated space and corpora albicantia, while the third nerve issues from the inner side of each crus, and the fourth nerve from the outer side ; on their upper aspect they are inseparable from the corpora quadrigemina. A transverse sec- tion (Fig. 315) shows the crura to be divisible into two parts, an upper, called the tegmentum, and a lower, the crusta; separated by a transverse band of pigmented grey matter, the locus niger. The tegmentum is traversed in the middle line near its upper part by the aqueduct of Sylvius, which in cross-section is triangular or T-shaped ; and beneath the floor of this canal is a small grey nucleus on each side which gives origin to the third nerves. Beneath the nucleus of the third, a bundle of longitudinal nerve fibres is seen, constituting the pos- terior longitudinal bundle (p.l.b.), and about the middle of the peduncle there is a spheroidal mass of nuclear matter, named from its colour the red nucleus; it is traversed by the fibres of the third nerve. The bulk of the tegmentum is formed by a continuation upwards of the formatio reticularis of the pons, which is in its turn continued into a reticular layer beneath the thalamus. Towards the outer side, however, is a band of white fibres called the fillet; it lies Pig. 315.—Transverse section of crura cerebri. CQ. Corpora quadrigemina. Aq. Aqueduct of Sylvius, p.l.b. Pos- terior longitudinalbundle. F. Olivary fdlet. UN. Red nucleus. SN. Sub- stantia nigra. TOC. Fibres passing between cerebellum and temporo- sphenoidal convolutions. Py. Pyra- midal tract. Fc. Fibres passing to fron- tal convolutions from cerebellum. III. Origin of the third nerve. 524 LINING MEMBRANE OF THE VENTRICLES. immediately above the locus niger, and reaching the surface of the tegmentum, forms a white band round its outer surface, below the corpora quadrigemina. The crusta is composed entirely of longi- tudinal nerve bundles communicating between the cerebrum and medulla, and the cerebrum and cerebellum. The middle band is the largest, and consists of the fibres of the pyramidal tract; the band on the outer side contains fibres passing to the temporo-occi- pital convolutions ; and that on the inner side, fibres connecting the frontal lobes and cerebellum. The two crusta are completely separate; the tegmenta are united, but their line of fusion is marked by an incomplete septum. The locus niger {substantia nigra) is composed of deeply pigmented nerve-cells with many branching processes ; nothing is known of the connections or uses of this large mass of grey matter. Lining Membrane of the Ventricles. The lining membrane of the ventricles, ependyma ventriculorum, is a serous layer distinct from the arachnoid ; it lines the whole of the interior of the lateral ventricles, and is connected with the attached border of the choroid plexus, so as to exclude direct communication between the lateral ventricles and the exterior of the brain. From the lateral ventricles it is reflected through the foramen of Monro on each side into the third ventricle, which it invests throughout. From the third it is conducted into the fourth ventricle, through the iter a tertio ad quartum ventriculum, and after lining its interior becomes continuous interiorly with the sub-arachnoid tissue of the spinal cord. The lining mem- brane of the ventricles is provided with an epithelium which is ciliated in patches and is the source of the secretion which moistens and lubricates their interior. The fifth ventricle has a separate lining membrane. The epithelium of the ependyma ventriculorum is supported by a delicate layer of modified connective tissue, similar to that de- scribed in the spinal cord under the name of neuroglia. White Matter of the Cerebrum. The white matter of the cerebrum consists of medullated nerve- fibres, varying in size in different parts, but generally smaller than those of the spinal cord and medulla. They may be conveniently arranged into three sets, viz., (i) ascending or peduncular, (2) transverse or commissural, and (3) longitudinal or collateral. The peduncular fibres may again be divided into (a) those ascend- ing in the crusta of the crus, and (b) those reaching the cerebrum through the tegmentum. The fibres derived from the crusta pass chiefly in the inner capsule of the corpus striatum, and from thence into the white centre of the hemispheres, where they spread out in a fan-like arrangement, forming the corona radiata, and ultimately reach the ARTERIES OF THE BRAIN. grey cortex of the convolutions. The most definite band of these fibres is continued upwards from the pyramidal tract of the medulla, and passes to the convolutions bordering on the fissure of Rolando {motor area of the cortex). Another set of these fibres passes from the lateral part of the crusta to the occipital lobe of the cerebrum {direct sensory tract). The innermost fibres of the crusta may be traced beneath the thalamus to terminate in the under part of the len- ticular nucleus {ansa lenticular is). The fibres of the tegmentum consist of the bundles traversing the formatio reticularis ; they are joined by those passing from the cerebellum in the processus e cere- bello ad testes, and probably some strands from the corpora quadri- gemina and other nuclei. Passing beneath the thalamus they enter that nuclear mass, but some run on the outer side thereof, to join the corona radiata, and pass from thence to the cortex of the temporo- sphenoidal and occipital lobes. The transverse or commissural fibres include (1) the anterior commissure of the third ventricle, (2) the posterior commissure, and (3) the transverse fibres of the corpus callosum. The longitudinal or collateral fibres include the following : viz., (1) the fornix, (2) taenia semicircularis, (3) striae longitudinales of the corpus callosum, (4) fibres of the gyrus fornicatus (superior longitudinal commissure), (5) a white bundle of fibres at the bottom of the fissure of Sylvius, connecting the frontal with the temporo-sphenoidal lobe and called the uncinate fasciculus, (6) a bundle of fibres lying in the outer Avail of the posterior and middle horns of the lateral ventricles, connecting the occipital and temporo-sphenoidal lobes, and named the inferior longitudinal fasciculus, and (7) association fibres passing between the several convolutions, and betAveen different parts of the same convolution (A. Campbell Clark). The connection of the fibres in the cerebrum with those in the medulla and spinal cord Avill be best understood from the table given on page 526, and derived chiefly from J. Ry lands Whitaker. 525 Arteries of the Brain. The arteries of the brain present certain peculiarities which render it necessary that they should he studied apart from the general arterial system, and along with the organ to which they are distributed. The important anastomotic connection at the base of the brain called the circle of Willis has been described on a previous page (402), and it is only necessary here to recall the fact that from that circle three main trunks, called anterior, middle, and posterior cerebral arteries, are given off on each side to the anterior, middle, and posterior regions of the brain. The branches derived from these trunks are of two kinds : medullary, which pass to the basal ganglia and neighbouring parts; and cortical, which are distributed to the convolutions of the five lobes into which the cerebrum is divided. These two systems of arteries are almost entirely independent of each other, what communications exist between them being very few CORD. MEDULLA. CRUS. CEREBRUM. Anterior f- Direct pyramidal tract. f Outer part of anterior pyramid of ) j the same side. j Lower part of crusta. C Through internal capsule to corona •j radiata, thence to convolutions l bordering on fissure of Rolando. Column. Anterior root zone. ( Posterior longitudinal bundle. j ■< Olivary peduncle and fillet. > ( Formatio reticularis. ) Tegmentum. j Corpora quadrigemina. j Optic thalamus. ( I. Crossed pyramidal ( Inner part of anterior pyramid of (_ Lower part of f Internal capsule. J Corona radiat'R. tract. j opposite side. 1 crusta. ( Motor convolutions. Lateral Column. 2. Direct lateral cerebellar tract. | Restiform body. | Cerebellum. f Olivary fillet. 1 C Corpora quadrigemina. 3- Mixed zone. < Formatio reticularis. Tegmentum. ■( Optic thalamus. Fasciculus teres. j ( Sensory convolutions. Posterior Postero-internal. | Funiculus gracilis. Tegmentum. J Probably the thalamus and corpora 1 quadrigemina. Column. I 2. Postero-external. / Funiculus cuneatus. | \ Formatio reticularis. / Tegmentum. / Probably the lenticular nucleus and \ inner capsule. TABLE showing the Course of the Fibres in the Spinal Cord, Medulla, Crus Cerebri and Cerebrum. ARTERIES OF THE BRAIN. 527 in number, and of capillary minuteness; the individual branches also of each system are distributed to independent areas, and only communicate with their fellows at the margins of those areas, by few and small communications ; hence they are distinguished as end arteries. As a necessary result of this arrangement, one artery cannot take the place or perform the work of another, as we so often find to be the case in other parts of the body, but if an artery becomes plugged, the area to which it is distributed becomes deprived of nourishment and rapidly undergoes degeneration. The following is a brief description of the chief branches of the three arteries men- tioned above. Anterior Cerebral.—The medullanj branches of this trunk are few in number; they are given off close to its origin from the in- ternal carotid, pass through the anterior part of the substantia per- forata, and are distributed to the front of the corpus striatum, and genu of the corpus callosum. The cortical branches are four in number. The first of these is distributed to the internal orbital convolutions ; the second to the anterior part of the marginal con- volution, the anterior part of the middle frontal convolution, and the superior frontal convolution ; the third to the inner surface of the hemisphere as far back as the ascending portion of the calloso- marginal fissure. The fourth supplies the quadrate lobe, and gives off a branch which enters the corpus callosum and supplies its structure. Middle Cerebral.—This is the largest artery of the three, and from its position is frequently named the Sylvian artery; it is distributed chiefly to the motor convolutions of the brain. The medullary branches are numerous ; they enter the openings in the substantia perforata, and passing directly upwards are distributed to the extraventricular nuclei of the corpus striatum, and the back part of the nucleus caudatus. The main trunk of the middle cerebral passes upwards in the fissure of Sylvius, and as it lies against the island of Reil divides into four cortical branches. The first of these is distributed to the outer part of the orbital surface and inferior frontal convolution ; the second to the posterior part of the middle frontal and three-fourths of the ascending frontal convolution ; the third to the rest of the ascending frontal, ascending parietal, and anterior part of the superior parietal, and the fourth to the in- ferior parietal (supra-marginal) and superior temporo-sphenoidal convolution. Posterior Cerebral.—Most of the medullary branches of this artery enter the locus perforatus posticus, but a few are given off on the outer side of the crus cerebri; both sets are distributed to the thalamus opticus, crus cerebri, and corpora quadrigemina. The cortical branches are three in number; the first passes to the an- terior part of the uncinate gyrus, the second to the back part of the same convolution and the lower part of the temporo-sphenoidal lobe, and the third to the occipital lobe. The convolutions to which this artery is distributed are for the most part sensory in function. 528 TOPOGRAPHY OF THE BRAIN. Relations of the Chief Sulci and Convolutions to the Exterior of the Skull. The relations of the sulci and convolutions of the cerebrum to the exterior of the skull are of great importance, in consequence of the increasing frequency with which operations are now performed for the removal of tumours and other morbid products from the con- Fig. 316.—Relations of the brain to the exterior of the skull, c.c. Coronal suture. Sq. Squamous suture, v. Back part of transverse suture, v1. Squamo-sphenoidal suture. LI. Lambdoidal suture. T. Inferior temporal ridge. ITh Superior temporal ridge, x. Stephanion. p. Pterion, a. Asterion. FhF2, and FA First, second, and third frontal convolutions. A.F. Ascending frontal convolution. Ji. Fissure of Rolando. A.F. Ascending parietal convolution. S- Fissure of Sylvius ; at p. its ascending portion is seen. 1.1. Inter-parietal fissure. S.P. Superior parietal gyrus. I.P. Inferior parietal gyrus. An. Angular gyrus. P.0. Parieto-occipital fissure. 0l,02, and 0s. First, second, and third occipital gyri. Tl, T-, and T'&. First, second, and third temporal gyri. volutions. Our space will only permit of a brief notice of tlie chief “landmarks” useful in such operations. The longitudinal fissure corresponds to a line drawn from the root of the nose (nasion) to the external occipital protuberance {inion). Fissure of Sylvius.—The bifurcation of this fissure corresponds to a point an inch and a quarter behind the external angular process of the frontal and about a quarter of an inch above its lower extre- mity. From this point the vertical portion passes directly upwards for about three-quarters of an inch, running parallel to and imrne- MEMBRANES OF THE BRAIN. 529 diately behind the coronal suture. The horizontal limb of this fissure corresponds to a line drawn from a point an inch and an eighth behind the external angular process to a little below the most pro- minent part of the parietal eminence ; it is covered for the middle three-fifths of its course by the upper part of the squamous suture. Fissure of Rolando.—The upper end of this fissure is situated at a point on the line from the nasion to the inion measuring 55.6 per cent, of the whole line, starting from the front {Hare's line). It runs downwards and forwards for about 3I inches, forming an angle of 67° with the line of the sagittal suture (middle line). Its lower end is situated about half an inch behind the bifurcation of the fissure of Sylvius and close to the horizontal limb. Reid, in order to define the position of the fissure of Rolando more accurately, takes a base line from the lowest part of the infra-orbital margin, through the external auditory meatus to the back of the head; he next marks out the course of the fissure of Sylvius according to the above rules ; two vertical lines are then drawn, reaching from the base line to the line of the sagittal suture, one passing through the depression in front of the auditory meatus, and the other through the posterior border of the mastoid process. A line drawn from the upper end of the posterior line to the point where the anterior one crosses the fissure of Sylvius, marks out the course of the fissure of Rolando. The parieto-occipital fissure runs horizontally outwards from the longitudinal fissure, at a point about one-fifth of an inch in front of the lambda. If the line marking the horizontal part of the fissure of Sylvius is continued backwards till it reaches the sagittal suture, the posterior inch of its course will mark the parieto-occipital fissure. Membranes of the Brain. Dissection.—To examine tlie brain with its membranes, the upper part of the skull must be removed, by sawing through the external table and breaking the internal table with the chisel and hammer. After the calvarium has been loosened all round, it will require a considerable degree of force to tear the bone away from the dura mater. This adhesion is particularly firm at the sutures, where the dura mater is continuous with a membranous layer in- terposed between the edges of the bones ; in other situations the connection results from numerous vessels which permeate the inner table of the skull. The adhesion subsisting between the dura mater and bone is greater in the young subject and in old persons than in the adult. On being torn away, the internal table will present numerous deeply grooved and ramified channels, corresponding with the branches of the meningeal arteries. Along the middle line will be seen a groove corresponding with the superior longitudinal sinus, and on either side may be frequently observed some small fossae, corresponding with the Pacchionian bodies. The membranes of the brain and spinal cord are—the dura mater, arachnoid, membrane, and pia mater. 530 MEMBRANES OF THE BRAIN. The dura mater is the firm whitish or greyish layer which is brought into view when the calvarium is removed. It is a strong fibrous membrane, somewhat laminated in texture, and composed of white fibrous tissue. Lining the interior of the cranium, it serves as the internal periosteum of that cavity ; it is prolonged also into the spinal column, hut is not adherent to the bones in that canal as in the cranium. It is very firmly attached to the margin of the foramen magnum, and to the foramina of exit of the cranial nerves. From the internal surface of the dura mater, processes are directed inwards for the support and protection of parts of the brain ; while from its exterior, other processes are prolonged outwards to form sheaths for the nerves as they quit the skull. Its external surface is rough and fibrous, and corresponds with the internal table of the skull. The internal surface is smooth, and lined by endothelium ; it was formerly regarded as a reflected layer of the arachnoid membrane. On the external surface of the dura mater the branches of the middle meningeal artery may be seen ramifying ; and in the middle line is a depressed groove, formed by the subsidence of the upper wall of the superior longitudinal sinus. The Pacchionian bodies (glandules Pacchioni) are small, round, whitish granulations, occurring singly or in clusters, and forming small groups of various sizes along tlie margin of the longitudinal fissure of the cerebrum, and more particularly near the summit of the latter. They are absent in infancy, increase in numbers in adult life, and are abundant in the aged. They are simply enlarged villi of the arachnoid, and consist of a spongy tissue continuous with the sub-arachnoid tissue and of the same composition, covered by a layer of epithelial cells. When of large size they cause absorption of the bone, and so come to be lodged in depressions or pits in the interior of the vertex of the skull. If the student cut through one side of the dura mater, in the direction of his incision through the skull, and turn it upwards towards the middle line, he will observe the smooth internal surface of this membrane. He will perceive also the large veins of the hemispheres passing from behind forwards to open into the superior longitudinal sinus. If he introduce the handle of his scalpel between the dura mater and arachnoid, he will see a vertical layer of the former descending between the hemispheres ; and if he draw one side of the brain a little outwards, he will be enabled to perceive the extent of the process of membrane which is called the falx cerebri. The processes of dura mater which are sent inwards towards the interior of the skull are the fnh: cerebri, tentorium cerebelli, and falx cerebelli. The falx cerebri (falx, a sickle, so named from its sickle-like appearance), narrow in front, broad behind, and forming a sharp curved edge below, is attached in front to the crista galli process of the ethmoid bone, and behind to the tentorium cerebelli ; between these points it is connected with the inner surface of the cranium in the middle line. Along the attached border runs the superior TENTORIUM AND FALX CEREBELLI. longitudinal sinus, and along the free edge the inferior longitudinal sinus, these vessels being situated between the two layers of which the membrane is composed. The tentorium cerebelli (tentorium, a tent) is a roof of dura mater (raised in the centre and sloping down at the sides) thrown across the cerebellum and attached at each side to the margin of the petrous portion of the temporal bone ; behind, to the transverse ridge of the occipital bone which lodges the lateral sinuses ; and in front to the upper border of the petrous portion of the temporal bone and to the anterior and posterior clinoid processes. It supports Fig. 317.—Sinuses and membranes of the brain (side view). 1. Superior longitudinal sinus. 2. Falx cerebri. 3. Fifth nerve. 4. Inferior longitudinal sinus. 5. Fourth nerve. 6. Vense Galeni. 7. Third nerve. 8. Tentorium cerebelli. 9. Second nerve. 10. Straight sinus. 11. Crista galli of ethmoid. 12. Torcular Herophili. 13. First nerve. 14. Falx cerebelli. 15. Sixth nerve. 16. Eighth, ninth, and tenth nerves. 17. Seventh and eighth nerves. 18. Vertebral artery. 19. Eustachian tube. 20. First cervical nerve. 21. Twelfth nerve. 22. Posterior root of second cervical nerve. 23. Anterior root of second cervical nerve. 24. Ligamentum denticulatum. the posterior lobes of the cerebrum and prevents their pressure on the cerebellum, leaving a small opening anteriorly (superior occipital foramen), for the transmission of the crura cerebri. Its attached bor- der contains the lateral and superior petrosal sinuses, and the junction between it and the falx cerebri is channelled by the straight sinus. The falx cerebelli is a small process, generally double, attached to the vertical ridge of the occipital bone beneath the lateral sinus, and to the tentorium. It lodges the occipital sinuses and is received into the indentation between the two hemispheres of the cerebellum. Removal of the Brain.—The tentorium and falx cerebelli cannot MEMBRANES OF THE BRAIN. 532 be seen until the brain is removed ; but the attachments of the former should be studied on the dried skull, for it will have to be incised in the removal of the brain. That operation should now be performed, for which purpose divide the dura mater all round, on a level with the section through the skull, and carry the scissors deeply between tlie hemispheres of the brain in front, to cut through the anterior part of the falx ; then draw the dura mater backwards, and leave it hanging by its attachment to the tentorium. Raise the anterior lobes of the brain carefully with the hand, and lift the olfactory bulbs from the cribriform fossae with the handle of the scalpel. Then cut across the two optic nerves and internal carotid arteries. Next divide tlie infundibulum and third nerves, and carry tlie knife along the margin of the petrous bone at each side, so as to divide the tentorium near its attachment. Cut across in succession the other pairs of cranial nerves with a sharp knife, and pass the scalpel as far down as possible into the vertebral canal, to sever the spinal cord, cutting first to one side, and then to the other, in order to divide the vertebral arteries and spinal accessory nerves. Then press the cerebellum gently upwards with the fingers of the right hand, the hemispheres being supported with the left, and the brain will roll into the hand. The arteries of the dura mater are—the anterior meningeal from the ethmoidal, ophthalmic, and internal carotid ; the middle menin- geal and lesser meningeal from the internal maxillary ; the inferior meningeal from the ascending pharyngeal and occipital arteries ; and the posterior meningeal from the vertebral. Its nerves are derived from the nervi molles and superior cervical ganglion of the sympathetic, from the Gasserian ganglion, the oph- thalmic nerve, and from the fourth and hypoglossal. The dura mater is composed of two lamellae, endosteal and proper meningeal; the former adheres to the bones, the latter forms the internal processes, whilst the sinuses result from the separation of the two. It consists of interwoven bands of white fibrous tissue, with some admixture of elastic fibres ; its inner surface is lined with flattened nucleated endothelial cells. The space between the dura mater and arachnoid is called the sub- dural space; it was formerly known as the cavity of the arachnoid. The arachnoid (dpdxvg e!8os, like a spider’s web) is a delicate membrane which invests the brain externally to the pia mater. On the upper surface of the hemispheres it is transparent, but may be demonstrated as it passes across the sulci from one convolution to another by injecting with a blow-pipe a stream of air beneath it. At the base of the brain the membrane is opalescent and thicker than in other situations, and more easily demonstrable from the circumstance of stretching across the interval between the temporal lobes of the hemispheres. The space which is included between this layer of membrane and those parts of the base of the brain which are bounded by the optic commissure and fissures of Sylvius in front, and the pons Varolii behind, is termed the anterior sub- SUB-ARACHNOID SPACES. 533 arachnoid space. Another space formed in a similar manner between the under part of the cerebellum and the medulla oblongata, is the posterior sub-arachnoid space; and a third space, situated over the corpora quadrigemina and corpus callosum, may be termed the supe- rior sub-arachnoid space. These spaces communicate freely with each other, the anterior and posterior across the crura cerebelli, the ante- rior and the superior around the crura cerebri, and the latter and the posterior across the cerebellum in the course of the vermiform processes. The posterior space communicates by means of an open- ing called the foramen of Magendie with the cavity of the fourth ventricle ; and the anterior space has two small openings in its wall behind the roots of the glosso-pharyngeal nerves, which communicate with a pouch-like prolongation of the arachnoid beneath the flocculus. They communicate also with a still larger space formed by the loose disposition of the arachnoid around the spinal cord, the spinal sub- arachnoid space. The whole.of these spaces, with the lesser spaces between the convolutions of the hemispheres, constitute one large and continuous cavity which is filled with a limpid serous secretion, the sub-arachnoid or cerebrospinal fluid, a fluid which is necessary for the regulation of pressure, and protection of the cerebro-spinal mass. The arachnoid is connected to the pia mater by a delicate areolar tissue, which in the sub-arachnoid space is loose and filamen- tous. The serous secretion of the sub-dural space is very small in quantity as compared with the sub-arachnoid fluid. The arachnoid does not enter into the ventricles of the brain, but is reflected inwards upon the venae Galeni for a short distance only, and returns upon those vessels to the dura mater of the tentorium. It surrounds the nerves as they originate from the brain, and forms a sheath around them to their point of exit from the skull. Vessels of considerable size, but few in number, and branches of cranial nerves, are found in the arachnoid. Structure.—The arachnoid consists of interlacing bundles of fine fibrous tissue, the interstices of which are occupied by spread-out cells. Its outer surface is covered by a layer of endothelium. On its inner surface it gives off numerous bundles of fibres which form trabeculae and traverse the sub-arachnoid spaces ; both the surface of the membrane and the trabeculae are covered by endothelial cells. Cerebro-Spinal Fluid.-—This is a limpid fluid, slightly alkaline in reaction, containing albumen, a trace of grape sugar, and the salts of the blood. The pia mater is an areolo-vascular membrane composed of in- numerable vessels held together by fine bundles of connective tissue. It invests the whole surface of the brain, dipping into the sulci be- tween the convolutions, and forming a fold in its interior called velum interpositum. It also forms folds in other situations, as in the third and fourth ventricles, and in the anterior fissure of the spinal cord. This membrane differs in structure in different parts of the cerebro-spinal axis. Thus, on the surface of the cerebrum, in contact with the soft grey matter of the brain, it is extremely vas- 534 MEMBRANES OF THE SPINAL CORD. cular, forming remarkable loops of anastomosis in the interspaces of the convolutions, and distributing multitudes of minute straight vessels to the grey substance. In the substantia perforata, again, and locus perforatus, it gives off tufts of small arteries, which pierce the white matter to reach the grey substance in the interior. But upon the crura cerebri, pons Varolii, and spinal cord, its vascular character seems almost lost. It has become a dense fibrous membrane, difficult to tear off, and forming the proper sheath of the spinal cord. The pi a mater is the nutrient membrane of the brain, and derives its blood from the internal carotid and vertebral arteries. Lympha- tics have also been described as entering into its structure. Its nerves are the minute filaments of the sympathetic, and filaments from the sensory cranial nerves; they accompany the branches of the arteries. The dura mater spinalis is a cylindrical slieatli of fibrous mem- brane, identical in structure with the dura mater of the skull, and continuous with that membrane. At the margin of the occipital fora- men it is closely adherent to the bone ; by its an- terior surface it is attached to the posterior common ligament, and be- low, by means of its pointed ex- tremity, to the coccyx. In the rest of its extent it is compara- tively free, being separated from the vertebrae by loose areolar tissue and a plexus of veins. On either side and below, the dura mater forms a sheath for each of the spinal nerves, to which it is closely adherent. Upon its inner surface it is smooth, and on its sides may be seen double openings for the two roots of each of the spinal nerves. MEMBRANES OF THE SPINAL CORD. Fio. 318.—Fourth ventri- cle and upper part of spinal cord and mem- branes. The posterior roots of the nerves are removed on the left side. 1. Corpora quad- rigemina. 2. Fillet of the olivary body. 3. Processus e cerebelio ad testes. 4. Processus e cerebelio ad pontem. 5. Processus e cerebelio admedullam. 6. Floor of fourth ventricle. 7. Glosso - pharyngeal nerve. 8. Pneumogas- tric nerve. 9. Spinal accessory nerve. 10. Posterior pyramids of medulla, n, n. An- terior divisions of spinal nerves. 12, 12. Ganglia of nerves. 13, 13. Posterior divisions of spinal nerves. 14, 14. Posterior roots of spinal nerves. 15. Line of origin of posterior roots of left side. 16, 16. Ligamentum denti- culatum. 17, 17. An- terior root of spinal nerves. 18. Dura mater. MEMBRANES OF THE SPINAL CORI). 535 The arachnoid of the spinal cord is a continuation of that of the brain. It encloses the cord very loosely, being connected to it only by long slender filaments of areolar tissue, and by a longitudinal lamella which is attached to the posterior aspect of the cord (septum posticum). The areolar tissue is most abundant in the cervical region, and diminishes in quantity from above downwards; and the septum posticum is complete only in the dorsal region. The arachnoid passes off from the cord on either side with the spinal nerves, to which it forms a sheath. The space between the arachnoid and the pia mater is identical with that already described as existing between the same parts in the brain, the sub- arachnoid space. It is occupied by cerebro - spinal fluid, sufficient in quantity to expand the arachnoid, and fill completely the cavity of the dura mater. The sub-arachnoid or cerebro-spinal fluid keeps up a constant and gentle pressure on the entire surface of the brain and spinal cord, and yields with the greatest facility to the various movements of the cord. The pia mater is the immediate investment of the cord, and, like the other membranes, is continuous with that of the brain. It is not, however, like the pia mater cerebri, a vascular membrane, but is dense and fibrous in structure, and contains but few vessels. It invests the cord closely, and sends a fold into the anterior median fissure; it is intimately connected with the neuroglia of the cord and with that occupying the posterior median fissure. It forms a sheath for each of the funiculi of the nerves, and for the nerves themselves; and, interiorly, at the conical termination of the cord, is prolonged downwards as a slender ligament (filum terminate), which descends through the centre of the cauda equina, and is attached to the dura mater lining the canal of the coccyx. This attachment is a rudiment of the original extension of the spinal cord into the canal of the sacrum and coccyx. A longitudinal band of white fibres runs down the centre of the anterior aspect of the cord, and was called by Haller the linea splendens. The pia mater has, distributed to it, a number of nervous plexuses. The ligamentum dentieulatum (ligamentum dentatum) is a thin process of pia mater sent off from each side of the cord throughout its entire length, and separating the anterior from the posterior roots of the spinal nerves. At its inner edge it is attached to the lateral aspect of the cord, and at its outer edge forms numerous saw-like processes or denticulations, the points of which are connected with the inner surface of the dura mater. The number of serrations on each side is about twenty, the first being situated on a level with the occipital foramen, and having the vertebral artery and hypoglossal Fig. 319.—Transverse section of the spinal cord and its membranes. 1. Dura mater. 2. Inner lining of dura mater. 3. Arachnoid. 4. Sub- dural space. 5. Sub-arachnoid space. 6. Anterior root of nerve. 7. Liga- mentum dentieulatum. 8. Gan- glion on posterior root of nerve. 536 CRANIAL NERVES. nerve passing in front and the spinal accessory nerve behind it, and the last opposite the first or second lumbar vertebra. Below this point the ligamentum denticulatum is lost in the filum terminal e of the pia mater. The denticulations do not pierce the arachnoid, but are covered by funnel-like prolongations of that membrane. The use of this membrane is to maintain the position of the spinal cord in the midst of the fluid by which it is surrounded. CRANIAL NERVES The pairs of cranial nerves are nine or twelve in number, ac- cording as the arrangement of Willis or Soemmering is adopted. The following table shows their numbering according to both systems, and also gives the names by which the several nerves are known :— Willis. Soemmering. Name. First. First. Olfactory. Second. Second. Optic. Third. Third. Oculo-motor. Fourth. Fourth. Pathetic or trochlear. Fifth. Fifth. Trifacial or trigeminal. Sixth. Sixth. Abducens. Seventh - f portio dura. Seventh. ) portio mollis. Eighth. Facial. Auditory. Eighth. ( Ninth. ' Tenth. [ Eleventh. Glosso-pharyngeal. Vagus. Spinal accessory. Ninth. Twelfth. Hypoglossal. In the following description we shall follow the arrangement of Soemmering, as being that most commonly adopted by anatomists at the present time. FIRST PAIR.—OLFACTORY. The olfactory tract is more truly a lobe or offshoot of the brain than a cranial nerve ; it arises by three roots : an inner or short root from the inner and posterior part of the anterior lobe close to the substantia perforata; a middle root from a papilla of grey matter {tuber olfadorium), embedded in the under surface of the frontal lobe, and an external or long root, which may be traced as a white streak along the fissure of Sylvius into the temporo-sphenoidal lobe. The nervous cord formed by the union of the three roots is soft in texture, prismoid in shape, and embedded in the olfactory sulcus on the under surface of each anterior lobe of the brain, lying between the pia mater and arachnoid. As it passes forward it increases in breadth, and swells at its extremity into an oblong mass of grey and white substance, the olfactory bulb, which rests on the cribriform plate of the ethmoid bone. From the under surface of the olfactory bulb are given off the nerves which pass through the cribriform foramina, and supply the mucous membrane of the nares ; they are arranged into three groups : an inner group, which spread out upon the septum narium ; an outer group, which descend through bony canals in the outer wall of the nares, and are distributed on the superior and middle turbinated bones ; and a middle group, which supply the mucous membrane of the roof of the nasal fossse. Each OLFACTORY AND OPTIC NERVES. 537 Fig. 320.—Olfactory nerves, with tlieir distribution on the septum nasi. The nares have been divided by a longitudinal section made immediately to the left of the septum, the right naris being preserved entire. 1. Frontal sinus. 2. Nasal bone. 3. Crista galli. 4. Sphenoidal sinus of left side. 5. Sella turcica. 6. Basilar pro- cess of sphenoid and occipital bone. 7. Posterior opening of the right naris. 8. Opening of the Eustachian tube. 9. Soft palate. 10. Cut surface of the hard palate, a. Olfactory tract, b. Its three roots of origin, c. Its bulb, from which the filaments are seen to proceed which spread out in the substance of the pituitary membrane, d. Nasal branch of the ophthalmic nerve, e. Naso-palatine nerve, distributing twigs to the mucous membrane of the septum nasi in its course to (/) the anterior palatine foramen, g. Branches of the naso-palatinp nerve to the palate, h. Anterior and posterior palatine nerves, i. Septum nasi. nerve is enclosed in a tabular prolongation of the dura mater and pia mater. The nerves are devoid of medullary sheath, and form frequent anastomoses with each other. SECOND PAIR.—OPTIC. Tliis nerve consists of three parts : the optic tract, the optic chiasma, and the nerve proper. The first portion arises from the corpora genicnlata on the posterior and inferior aspect of the thala- mus opticus, from the thalamus itself, and from the nates. Pro- 538 CRANIAL NERVES. ceeding from this origin it winds around the crus cerebri as a flattened band, and joins with its fellow in front of the tuber cine- reum to form the optic commissure (chiasma). The optic tract is united with the crus cerebri and tuber cinereum, and is covered by the pia mater; the commissure is also connected with the tuber cinereum, from which it receives fibres, and the nerve beyond the commissure diverges from its fellow, becomes rounded in form, and is enclosed in a sheath derived from the arachnoid, which is con- tinued upon it to the eyeball. In passing through the optic foramen the optic nerve receives a sheath from the dura mater, which splits at this point into two layers : one, which becomes the periosteum of the orbit; the other, the one in question, which forms a sheath for the nerve, and is lost in the sclerotic coat of the eyeball. After a short course within the orbit the optic nerve pierces the sclerotic and choroid coats, and expands into the nervous membrane of the eyeball, the retina. Near the globe the nerve is pierced by a small artery, arteria centralis retinae, which runs through the central axis of the nerve and reaches the inner layers of the retina, to which it distributes branches. The optic commissure lies in a groove in front of the olivary body of the sphenoid bone; is bounded by the lamina cinerea in front, by the substantia perforata at each side, and by the tuber cinereum behind. Within the commissure the innermost fibres of each optic nerve cross each other to pass to the eye of the opposite side ; the outer fibres continue their course uninterruptedly to the eye of the corresponding side. Some fibres pass in an arched direction from one nerve to the other behind, and others, taking a similar course in front, connect the two retinae. THIRD PAIR.—MOTORES OCULORUM. The motor oculi, a nerve of moderate size, arises from the inner side of the crus cerebri, close to the pons Varolii, and passes forward between the posterior cerebral and superior cerebellar arteries. Its deep origin has been traced through the locus niger, to a grey nucleus beneath the floor of the aqueduct of Sylvius and beneath the corpora quadrigemina. It pierces the dura mater immediately in front of the posterior clinoid process ; descends obliquely in the external wall of the cavernous sinus ; and divides into two branches which enter the orbit through the sphenoidal fissure and between the two heads of the external rectus muscle. The superior branch ascends, and supplies the superior rectus and levator palpebrae. The inferior sends a branch beneath the opt ic nerve to the internal rectus, another to the inferior rectus, and a long branch to the inferior oblique muscle. From the latter a short thick branch is given to the ophthalmic ganglion, forming its inferior root. The branches of the third nerve enter the muscles on their ocular side. In the cavernous sinus it receives one or two filaments from the carotid plexus, and one from the ophthalmic nerve. FOURTH AND FIFTH NERVES. 539 FOURTH PAIR.—PATHETICI (trochlearis). The fourth is the smallest cerebral nerve ; it arises from a nucleus beneath that of the third nerve in the floor of the aqueduct of Sylvius; it passes across the outer border of the valve of Vieussens, and wind- ing around the crus cerebri to the extremity of the petrous portion of the temporal bone, pierces the dura mater below the third nerve, and passes forward in the outer wall of the cavernous sinus to the sphenoidal fissure. In its course in the outer wall of the sinus it is situated at first below the motor oculi, but afterwards ascends and becomes the highest of the nerves entering the orbit by the sphenoidal fissure. On entering the orbit the nerve crosses the levator palpe- brse muscle near its origin, and is distributed on the orbital surface of the superior oblique or trochlearis muscle; hence its synonym trochlearis. The fibres of origin of the two nerves communicate with each other, forming a kind of commissure, on the upper surface of the valve of Vieussens. Branches.—While in the cavernous sinus the fourth nerve gives off a recurrent branch, and sends a branch of communication to the ophthalmic nerve ; the recurrent branch, consisting of sympathetic filaments derived from the carotid plexus, passes backwards between the layers of the tentorium, and divides into two or three filaments, which are distributed to the lining membrane of the lateral sinus. FIFTH PAIR.—TRIFACIAL (trigeminus), The fifth nerve, the great sensitive nerve of the head and face, and the largest cranial nerve, is analogous to the spinal nerves in its origin by two roots from the anterior and posterior columns of the spinal cord, and in the existence of a ganglion on the posterior root. It arises, or rather makes its appearance at the surface of the brain, on the anterior part of the lateral and constricted portion of the pons Varolii, and consists of a large and small fasciculus, separated by a narrow interspace, the larger fasciculus being the posterior or sensory root; the smaller one, the anterior or motor root. The sensory root is composed of from seventy to a hundred filaments each enclosed in a sheath of pia mater, and the entire bundle is bound together into a single nerve and connected with the motor root by a sheath of arachnoid membrane. The nerve then passes through an oval opening in the border of the tentorium, near the extremity of the petrous bone, and spreads out into a large semilunar ganglion, the Gasserian. If the ganglion be turned over, it will be seen that the anterior root lies against its under surface without having any connection with it, and may be followed onwards to the inferior maxillary nerve. The Gasserian ganglion divides into three branches—ophthalmic, superior maxillary, and inferior maxillary. Deep Origin.—The motor root arises (i) from a nucleus in the 540 CRANIAL NERVES. floor of the fourth ventricle, immediately below the lateral recess, and (2) from grey matter in the sides of the Sylvian aqueduct (de- scending root). The sensory root springs (1) from a long nucleus placed beneath the floor of the fourth ventricle and extending into the medulla in the region of the funiculus cuneatus (ascending root). and (2) from the nerve cells of the formatio reticularis in the medulla and pons. The OPHTHALMIC NERVE is the nerve of sensation of the eyeball, lachrymal gland, mucous membrane of the eye and nose, integument of the forehead and nose, and muscles of the eyebrow and forehead. It arises from the upper part of the Gasserian ganglion by a short trunk, about three-quarters of an inch in length ; passes forwards in the outer wall of the cavernous sinus, lying externally to the other nerves, and divides into three branches. Previously to its division it receives several filaments from the carotid plexus, and gives off a small recurrent nerve, which passes backwards with the recurrent branch of the fourth nerve between the two layers of the tentorium to the lin- ing membrane of lateral sinus. The branches of the ophthalmic nerve are the— Frontal, Lachrymal, Nasal. The frontal nerve enters the orbit imme- diately to the outer side of the fourth nerve, and passing forwards, for some distance, upon the levator palpebrae muscle, divides into a supra-orbital and supra-trochlear branch. The supra - orbital branch, the proper con- tinuation of the nerve, passes out of the orbit through the supra-orbital notch, in company with the supra-orbital artery, and after giving fila- ments to the upper eye- lid, muscles of the forehead and pericranium, divides into two cutaneous branches, internal and external. The internal branch pierces the occipito-frontalis and is distributed to the integument as Fig. 321.—Superficial dissection of the nerves of the orbit. 1. Supra-trochlear nerve. 2. Supra- orbital nerve. 3. Obliquus superior. 4. Lachry- mal gland. 5. lnfra-trochlear nerve. 6. Levator palpebral superioris. 7. Nasal nerve (fifth). 8. Frontal nerve (fifth). 9. Optic nerve. 10. Rectus superior, n. Third nerve. 12. Lachrymal nerve. 13. Fourth nerve. 14. Gasserian ganglion of fifth. 15. Sixth nerve. OPHTHALMIC NERVE. far as the summit of the head. The external branch of larger size communicates with the facial nerve, and piercing the occipito- frontalis supplies the integument as far back as the occiput. The supra-trochlear branch passes inwards to the angle of the orbit, above the superior oblique muscle and close to the pulley, and is distributed to the inner angle of the eye, root of the nose, and in- 541 Fig. 322.—Diagram showing the fifth pair of nerves with its branches. 1. Origin of the nerve by two roots. 2. The nerve escaping from the pons Varolii. 3. Gas- serian ganglion. 4. Ophthalmic nerve. 5. Frontal nerve giving off the supra- trochlear branch. 6. Lachrymal nerve. 7. Nasal nerve passing at 8 through the anterior internal orbital foramen, and giving off the infra-trochlear branch. 9. Superior root of the ophthalmic ganglion given off from nasal nerve. 10. Inferior or motor root, derived from third nerve ; the ganglion gives off the ciliary nerves from its anterior aspect. 11. Superior maxillary nerve. 12. Orbital branch. 13. Spheno-palatine nerves communicating with Meckel’s ganglion ; the three branches from the lower part of the ganglion are the palatine nerves. 14, 14. Superior dental nerves, posterior, middle, and anterior. 15. Infra-orbital branches. 16. Inferior maxillary nerve. 17. Its anterior or muscular trunk. 18. The posterior trunk ; the two divisions are separated by an arrow. 19. Lingual nerve. 20. Chorda tympani joining it at an acute angle. 21. Submaxillary ganglion. 22. In- ferior dental nerve. 23. Mylo-hyoid branch. 24. Auriculo-temporal nerve, divid- ing behind the articulation of the lower jaw, to reunite and form a single trunk. 25. Its branch of communication with the facial nerve. 26. Continuation of its trunk to the temple. tegument of the middle line of the forehead. It communicates with the infra-trochlear branch of the nasal nerve. The lachrymal nerve, the smallest of the three branches of the ophthalmic, enters the orbit on the outer side of the frontal, but enclosed in a separate sheath of dura mater; and passes forward, above the upper border of the external rectus muscle, and in com- pany with the lachrymal artery to the lachrymal gland, where it divides 'into two branches, superior and inferior. The superior 542 CRANIAL NERVES. branch passes over the gland which it supplies on the upper surface. The inferior branch supplies the under surface of the gland, upper lid. and outer angle of the eye. It gives off a branch which passes downwards to join the orbital branch of the superior maxillary, and from the connection between these two nerves, temporo-malar fila- ments are derived which pass through foramina in the malar bone to be distributed to the outer part of the face and the temple, communi- cating with branches of the facial and auriculo-temporal nerves. The nasal nerve enters the orbit between the two heads of the external rectus and between the two branches of the third nerve. It Fio. 323.—Nerves of tlie orbit seen from the outer side. 1. Section of frontal bone. 2. Superior maxillary bone. 3. Part of sphenoid bone. 4. Levator palpebrse and supe- rior rectus muscles. 5. Superior oblique muscle. 6. Infe- rior oblique. 7. Ocular half of the external rectus drawn forwards. 8. Orbital half of the external rec- tus turned down- wards. On this muscle the sixth nerve is seen divid- ing into branches. 9. Inferior rectus. 10. Optic nerve. 11. Internal caro- tid artery emerg- ing from the cavernous sinus. 12. Ophthalmic artery. 13. Third nerve. 14. Branch of the third nerve to the inferior oblique muscle. Between this and the sixth nerve (8) is seen the branch which supplies the inferior rectus; its branch to the ophthalmic ganglion is seen proceeding from the upper side of the trunk of the nerve, at the bottom of the orbit. 15. Fourth nerve. 16. Trunk of the fifth nerve. 17. Gasserian ganglion. 18. Ophthalmic nerve. 19. Superior maxillary nerve. 20. Inferior maxillary nerve. 21. Frontal nerve. 22. Supra-orbital nerve. 23. Lach- rymal nerve. 24. Nasal nerve; the small nerve seen between the nasal and frontal, is one of the branches of the upper division of the third nerve. 25. Nasal nerve passing over the internal rectus muscle to the anterior internal orbital foramen. 26. In fra-trochlear nerve. 27. A long ciliary branch of the nasal; another long ciliary branch is seen proceeding from the lower aspect of the nerve. 28. Long root of the ophthalmic ganglion, proceeding from the nasal nerve, and receiving the sympathetic root which joins it at an acute angle. 29. Ophthalmic ganglion, giving off from its fore-part the short ciliary nerves. 30. Globe of the eye. crosses the optic nerve in company with the ophthalmic art ery, and, passing over the internal rectus, enters the anterior internal orbital foramen, by which it is conducted to the cribriform plate of the ethmoid bone. It then passes through the slit-like opening by the side of the crista galli, and descends into the nose, where it divides into an internal and external branch. The internal branch is dis- tributed to the mucous membrane ; the external branch, passing outwards between the nasal bone and cartilage, supplies the integu- ment of the exterior of the nose as far as its tip. The branches of the nasal nerve are—ganglionic, ciliary, and infra-trochlear. The ganglionic branch, about half an inch in length and of small size, enters the upper angle of the ophthalmic ganglion, and consti- tutes its superior or long root. It is often joined by the sympathetic root of the ganglion derived from the cavernous plexus. The long ciliary branches are two or three filaments given off from the nerve as it crosses the optic nerve. They pierce the sclerotic coat near the short ciliary nerves, and passing through the globe of the eye between the sclerotic and choroid, are distributed to the iris. The infra-trochlear branch is given off close to the anterior in- ternal orbital foramen. It passes forward along the upper border of the internal rectus to the inner angle of the eye, where it com- municates with the supra-troclilear nerve, and is distributed to the lachrymal sac and inner angle of the orbit. The SUPERIOR MAXILLARY NERVE, larger than the preceding, is the nerve of sensation of the teeth of the upper jaw, the hard and soft palate, tonsils, antrum maxillare, and muscles and integument of the lower eyelid, cheek, and upper lip. Proceeding from the middle of the Gasserian ganglion, it passes forward through the foramen rotundum, crosses the spheno-maxillary fossa, and enters the canal in the floor of the orbit, along which it runs to the infra- orbital foramen. Emerging on the face, beneath the levator labii superioris muscle, it becomes the infra-orbital nerve, and divides into palpebral, nasal, and labial branches, which form a plexus with the facial nerve. The branches of the superior maxillary nerve are divisible into three groups : namely, those given off in the spheno-maxillary fossa ; those given off in the infra-orbital canal; and those given off on the face. They may be thus arranged :— SUPERIOR MAXILLARY NERVE. 543 Spheno-maxillary fossa . Orbital, or temporo-malar, Spheno-palatine, Posterior dental. Infra-orbital canal . . Middle dental, Anterior dental. On the face Palpebral, Nasal, Labial. The orbital branch enters the orbit through the spheno-maxillary fissure, and divides into two branches, temporal and malar ; the temporal branch ascends along the outer wall of the orbit, and after receiving a branch from the lachrymal nerve, passes through a canal in the malar bone, and enters the temporal fossa ; it then pierces the temporal muscle and fascia, and is distributed to the integument of the temple and side of the forehead, communicating with the 544 CRANIAL NERVES. facial and auriculotemporal nerves. In the temporal fossa it com- municates with the deep temporal nerves. The malar, or inferior branch (subcutaneous mala.') takes its course along the lower angle of the outer wall of the orbit, and emerges on the cheek through an opening in the malar bone, passing between the fibres of the orbicu- laris palpebrarum muscle. It communicates with branches of the infra-orbital and facial nerve. The spheno-palatine branches, two in number, pass downwards to the spheno-palatine or Meckel’s ganglion. The posterior dental branches, two in number, pass downwards upon the tuberosity of the superior maxillary bone, where one enters Fig. 324. — Pterygo- maxillary region and fifth nerve. 1. Tem- poral fascia. 2. Tem- poral mu&cle. 3.Tem- poral branches of auriculo - temporal nerve. 4. Anterior deep temporal nerve. 5. Posterior deep temporal nerve. 6. External pterygoid muscle. 7. Deep tem- poral branch of mas- seteric nerve (in- constant). 8. Buccal nerve. 9. Masseteric nerve. 10. Buccal branch of seventh. 11. Auriculo-temporal nerve. 12. Lingual nerve. 13. Facial nerve at stylo-mas- toid foramen. 14. Buccinator muscle. 15. Internal ptery- goid. 16. Supra - maxillary branch of seventh. 17. Inferior dental nerve. 18. Its mental branches. 19. Its mylo - hyoid branch. 20. Inferior dental canal opened. 21. Masseter (turned down). a canal in the bone, and is distributed to the molar teeth and lining membrane of the antrum, and communicates with the anterior dental nerve ; while the other, lying externally to the bone, is dis- tributed to the gums and buccinator muscle. The middle and anterior dental branches descend to the corre- sponding teeth and gums ; the former beneath the lining membrane of the antrum, the latter through distinct canals in the walls of the bone. Previously to their distribution, the dental nerves form a plexus in the outer wall of the superior maxillary bone immediately above the alveolus. From this plexus filaments are given off which supply the pulps of the teeth, gums, mucous membrane of the floor INFERIOR MAXILLARY NERVE. 545 of the nares, and palate. Small ganglia have been described in connection with this plexus, one being placed over the canine, another over the second molar tooth ; the former has been named the ganglion of Bochdalelc. The palpebral branches are given off from the infra-orbital as it issues from the infra-orbital foramen; they turn upwards to the eyelid and are distributed to the skin, conjunctiva, and orbicnlaris palpebrarum (sensory supply). The nasal branches pass inwards between the fibres of the levator labii superioris alseque nasi to be distributed to the skin of the side of the nose and the extrinsic and intrinsic muscles (sensory supply). The labial branch lies on the levator anguli oris, and divides into branches for the skin of the cheek, mucous membrane of the upper lip, and muscles of the upper lip (sensory supply). The INFERIOR MAXILLARY NERVE'is a nerve both of sensation and motion, and is distributed to the teeth and gums of the lower jaw, to the tip and sides of the tongue, to the integument of the temple, external ear, lower part of the face and lower lip, and to the muscles of mastication. Its sensory root proceeds from the inferior angle of the Gasserian ganglion, is the largest of the three sensory divisions of the fifth nerve, and is increased in size by the anterior or motor root, which, passing behind the ganglion, unites with it as it escapes through the foramen ovale. Emerging at the foramen ovale the nerve divides into two trunks, anterior and posterior, separated from each other by the external ptery- goid muscle ; the anterior division is almost entirely motor, but its buccal branch is believed to be in chief part sensory ; the posterior division is sensory, but the mylo-hyoid branch of the inferior dental is motor. The anterior division, into which may be traced nearly the wdiole of the motor root, immediately separates into five or six branches, distributed to the muscles of the temporo-maxillary region ; they are—masseteric, temporal, buccal, internal pterygoid, and external pterygoid. The masseteric branch passing over the external pterygoid muscle, and behind the tendon of the temporal, crosses the sigmoid notch with the masseteric artery to the masse ter muscle. It sends a filament to the temporo-maxillary articulation, and frequently a small branch to the temporal muscle. The deep temporal branches, two in number, anterior and posterior, pass between the upper border of the external pterygoid muscle and the temporal bone to the temporal muscle. Two or three filaments from these nerves pierce the temporal fascia, and communicate with the lachrymal, subcutaneus make, superficial temporal and facial nerves. The buccal branch is of large size, and pierces the lower fibres of the external pterygoid muscle at its anterior part ; it runs down- wards and forwards in close contact with the inner surface of the tendon of the temporal muscle and accompanied by the bucca 546 CRANIAL NERVES. branch of the internal maxillary artery. It sends a branch to the external pterygoid muscle, and is distributed to the buccinator and mucous membrane and integument of the cheek, communicating with the facial nerve. The internal pterygoid branch is a long and slender nerve which passes inwards to the internal pterygoid muscle, and enters it on its deep surface. This nerve is remarkable for its connection with the otic ganglion, to which it is closely adherent. The external pterygoid branch is commonly derived from the buccal nerve. The posterior division of the inferior maxillary nerve splits into three branches— Auriculo-temporal, Inferior dental, Lingual. The AURICULO-TEMPORAL NERVE originates by two roots, be- tween which the middle meningeal artery takes its course, and passes directly backwards behind the articulation of the lower jaw. It then ascends between that articulation and the meatus auris, and, escaping from beneath the parotid gland, divides into two temporal branches. While behind the temporo-maxillary articulation, it forms a kind of plexus, and sends off several branches. Its branches are—a small branch to the temporo-maxillary articu- lation ; two or three to the parotid gland ; two to the meatus auris, which enter the canal between the fibro-cartilage and processus auditorius ; two auricular branches to the pinna ; a communicating branch to the otic ganglion ; two communicating branches to the facial nerve, and the temporal branches. The auricular branches, superior and inferior, are distributed to the pinna above and below the meatus. The inferior branch communicates with the sympathetic. The branches which communicate with the facial nerve embrace the external carotid artery in their course. The temporal branches are anterior and posterior : the anterior accompanies the anterior temporal artery, and supplies the integu- ment of the temporal region, communicating with branches of the facial, supra-orbital, subcutaneus mala), and lachrymal nerves ; the posterior is distributed to the upper part of the pinna, attrahens auriculam muscle, and integument of the posterior part of the temple. The INFERIOR DENTAL NERVE, the largest of the three branches of the posterior division of the inferior maxillary, passes downwards with the inferior dental artery, at first between the two pterygoid muscles, then between the internal lateral ligament and ramus of the lower jaw to the dental foramen, next it runs along the canal in the inferior maxillary bone, distributing branches to the teeth and gums, and divides into two terminal branches, incisive and mental. The branches of the inferior dental nerve, besides those given to the teeth, are the mylo-liyoid and the two terminal branches. The mylo hyoid branch leaves the nerve just as it is about to LINGUAL NERVE. 547 enter the dental foramen; it then pierces the insertion of the in- ternal lateral ligament, and descends along a groove in the hone to the inferior surface of the mylo-hyoid muscle, to which, and to the anterior belly of the digastricus, it furnishes the motor supply. The incisive branch is continued forward to the symphysis of the jaw, to supply the incisor teeth. The mental or labial branch emerges from the jaw at the mental foramen, beneath the depressor anguli oris, and divides into branches which supply the muscles (sensory supply) and integument of the lower lip and chin, and communicate with the facial nerve. The LINGUAL NERVE (igustatory) descends between the two ptery- goid muscles, and makes a gentle curve forwards to the side of the tongue, along which it takes its course to the tip. On the side of the tongue it is flattened, and gives off numerous 1 tranches, which are distributed to the mucous membrane and papilla*. In the upper part of its course the lingual nerve lies between the external pterygoid muscle and the pharynx, next between the two pterygoid muscles, then between the internal pterygoid and ramus of the jaw, crosses the upper border of the superior constrictor of the pharynx, and runs between the stylo-glossus muscle and the submaxillary gland ; lastly, it runs along the side of the tongue, resting against the hyo-glossus muscle and crossing the duct of the submaxillary gland, and lies between the mylo-hyoid muscle and the mucous membrane of the floor of the mouth. The lingual nerve, while between the pterygoid muscles, often receives a communicating branch from the inferior dental; lower down it is joined at an acute angle by the chorda tympani, a small nerve, which, arising from the facial in the aqueductus Fallopii, crosses the tympanum, and escapes from that cavity through the canal of Huguier at the inner end of the fissure of Glaser. Having joined the lingual nerve, the chorda tympani is continued down- wards in its sheath to the submaxillary ganglion and tongue. One or two branches are given by the lingual nerve to the submaxillary ganglion. On the hyo-glossus muscle several branches of communication join with branches of the hypoglossal nerve, and others are sent to the sublingual gland, Wharton’s duct, and mucous membrane of the mouth and gums. SIXTH PAIR.—ABDUCENTES. The abducens nerve, about half the size of the motor oculi, arises by several filaments from the groove between the anterior pyramid and the pons Varolii. Proceeding forwards from this origin, it lies parallel with the basilar artery, and, piercing the dura mater low down on the side of the basilar process of the sphenoid bone, ascends between the two layers of that membrane to the cavernous sinus. It then runs forward on the outer wall of the sinus, below the level of the other nerves and resting against the internal carotid artery, to the sphenoidal fissure. Entering the orbit through the 54S CRANIAL NERVES. sphenoidal fissure it passes between the two heads of the external rectus, and is distributed to that muscle. At the sphenoidal fissure it lies upon the ophthalmic vein, from which it is separated by a lamina of dura mater ; and in the cavernous sinus is joined by several filaments from the carotid plexus. Deep Origin.—Underneath the fasciculus teres in the floor of the fourth ventricle, immediately above the strife acusticae. The seventh and eighth pairs of nerves consist of two nervous cords which lie side l>y side on the posterior border of the crus cerebelli in the groove between the olivary and restiform bodies. The smaller and most internal of these, and at the same time the most dense in texture, is the seventh (facial nerve or portio dura). The external nerve, which is soft and pulpy, and often grooved by contact with the preceding, is the eighth or auditory nerve (portio mollis). A third nerve of small size, portio intermedia of Wrisberg, is brought into view by separating these two cords. It arises from the same nucleus as the auditory nerve, and generally joins the facial nerve where the two lie together in the internal audi- tory meatus. Some observers state that it is continued into the chorda tympani nerve beyond the gangliform enlargement of the facial. FACIAL OR SEVENTH NERVE (portio dura).—The facial nerve, the motor nerve of the face, arises from the upper part of the groove between the olivary and restiform bodies, close to the lower edge of the pons Varolii; its deep origin being traced to the for- inatio reticularis of the pons, beneath the floor of the fourth ventricle. The nerve passes forward, resting on the crus cerebelli, and comes into relation with the auditory nerve, with which it enters the meatus auditorius interims, lying at first to the inner side of, and then upon that nerve. At the bottom of the meatus, the facial nerve enters the aqueductus Fallopii, and takes its course forwards to the hiatus Fallopii, in the anterior wall of the petrous bone, where it forms a gangliform swelling (intumescentia gangli- formis, geniculate ganglion), and receives the petrosal branch of the Vidian nerve. It then runs along the inner wall of the tym- panum, and descends behind the pyramid and tympanic cavity to the stylo-mastoid foramen. Emerging at the stylo-mastoid foramen, it passes forwards within the parotid gland, crossing the external carotid artery, to the ramus of the lower jaw, where it splits into two trunks, temporo-facial and cervico-facial. These trunks divide into numerous branches, which escape from the anterior border of the parotid gland, and are distributed in a radiated manner over the side of the face, from the temple to below the lower jaw ; on the masseter muscle the branches communicate and form loops, and the whole arrangement over the side of the face has been termed pes anserinus. SEVENTH PAIR. Communications.—In the meatus auditorius, the facial nerve communicates with the auditory nerve by one or two filaments ; the intiunescentia gangliformis is connected with the greater and lesser petrosal nerves, and sends a twig hack to the auditory nerve ; at the back of the tympanum, the nerve receives one or two twigs from the auricular branch of the pneumogastric ; at its exit from the stylo-mastoid foramen it receives a twig from the glosso-pha- ryngeal, and in the parotid gland one or two large branches from the auriculo-temporal nerve. Besides these, the facial nerve has numerous peripheral communications, with the branches of the fifth nerve on the face, with the cervical nerves in the parotid gland and on the neck, and with the sympathetic. The branches of the facial nerve are— FACIAL NERVE. 549 Within the aqueductus Fallopii Tympanic, Cliorda tympani. After emerging at the stylo-mastoid foramen . Posterior auricular, Stylo-hyoid, Digastric. Temporo-facial, Cervico-facial. The tympanic branch is a small filament given off by the facial while in the petrous bone, and distributed to the stapedius muscle. The chorda tympani quits the facial immediately above the stylo-mastoid foramen, and ascends by a distinct canal to the upper part of the posterior wall of the tympanum, where it enters that cavity through an opening situated between the base of the pyramid and the attachment of the membrana tympani, and becomes invested by mucous membrane. It then crosses the tympanum between the handle of the malleus and long process of the incus to its anterior inferior angle, and escapes through an opening at the inner end of the fissure of Glaser (canal of Huguier), to join the lingual branch of the fifth at an acute angle between the two pterygoid muscles. Enclosed in the sheath of the lingual nerve, it descends to the sub- maxillary gland, where part of it ends in the submaxillary ganglion; the rest is continued onwards with the filaments of the lingual, to be distributed to the tongue. The origin of the chorda tympani has long been a subject of dis- cussion, some observers regarding it as derived from the intermediary nerve of Wrisberg, others considering it as traceable through the greater and lesser petrosal nerves to the spheno-palatine and otic ganglia ; latterly, there has been a growing opinion in favour of its origin from the communicating branch of the glosso-pharyngeal, which joins the facial nerve at the stylo-mastoid foramen. The posterior auricular branch ascends behind the ear, be- tween the meatus and mastoid process, and divides into an anterior or auricular, and a posterior or occipital branch. The auricular branch receives a filament of communication from the auricular branch of the pneumogastric nerve, and distributes filaments to the On the face CRANIAL NERVES. retrahens auriculam muscle and pinna. The occipital branch com- municates with the auricularis magnus and occipitalis minor, and is distributed to the occipital portion of the occipito-frontalis. The stylo-hyoid branch is distributed to the stylo-liyoid muscle, and communicates with the sympathetic plexus on the external carotid artery. The digastric branch supplies the posterior belly of the digas- tricus muscle, and communicates with the glosso-pharyngeal and Fig. 325.—Nerves of the face and scalp. 1. Attrahens auriculam muscle. 2. Anterior belly of occipito-frontalis. 3. Auriculo-temporal nerve. 4. Temporal branches of facial nerve. 5. Attollens auriculam muscle. 6. Supra-troclilear nerve. 7. Pos- terior belly of occipito-frontalis. 8. Supra-orbital nerve. 9. Retrahens auriculam muscle. 10. Temporal branch of orbital nerve (superior maxillary), n. Occipitalis minor nerve. 12. Malar branches of facial. 13. Posterior auricular. 14. Malar branch of temporo-malar. 15. Great occipital. 16. Infra-orbital branches of facial. 17. Facial. 18. Nasal branch of ophthalmic. 19. Cervico-facial division of facial. 20. Infra-orbital branch of fifth. 21. Branches of facial to digastric and stylo-hyoid. 22. Temporo-facial division of facial. 23. Great auricular. 24. Buccal branches of facial. 25. Trapezius muscle. pneumogastric nerves. This nerve and the preceding often arise from the facial by a common trunk. The TEMPORO-FACIAL DIVISION, while in the parotid gland, sends a branch of communication along the carotid artery to the AUDITORY NERVE. auriculo-temporal nerve, and divides into temporal, malar, and infra-orbital brandies. Tbe temporal branches ascending upon the temporal region supply tbe attrahens auriculam, occipito-frontalis, and orbicularis palpebrarum; and communicate with the supra-orbital nerve and temporal branch of the superior maxillary. The malar branches cross the malar bone to the outer angle of the eye, and supply the orbicularis palpebrarum, corrugator super- cilii, and eyelids. They communicate with the subcutaneus malm branch of the superior maxillary nerve, and with branches of the ophthalmic nerve in the eyelids. The infra-orbital branches cross the masseter muscle, and are distributed to the buccinator, elevator muscles of the upper lip, and orbicularis oris. They communicate with the terminal branches of the infra-orbital nerve, infra-trochlear, and nasal nerve. Two or more of these branches are found by the side of Stenson’s duct. The CERVICO-FACIAL DIVISION, smaller than the temporo-facial, communicates in the parotid gland with the auricularis magnus nerve, and divides into branches which admit of arrangement into three sets : buccal, supra-maxillarv, and infra-maxillary. The buccal branches pass forward across the masseter muscle towards the mouth, and distribute branches to the orbicularis oris and buccinator. They communicate with branches of the tem- poro-facial, and with the buccal branch of the inferior maxillary nerve. The supra-maxillary branches are destined to the muscles of the lower lip, and take their course along the body of the lower jaw. Beneath the depressor anguli oris, they have a plexiform communi- cation with the inferior dental nerve. The infra-maxillary branches take their course below the lower jaw, pierce the deep cervical fascia, and are distributed to the platysma, communicating with the superficialis colli nerve. EIGHTH NERVE. Auditory Nerve (portio mollis).—The auditory nerve takes its origin in the floor of the fourth ventricle from two nuclei—one in the tuberculum acusticum at the outer side of the inferior fovea, the other in the lateral recess. It winds around the restiform body, from which it receives fibres, to the posterior border of the crus cerebelli. It then passes forward on the crus cerebelli in company with the facial nerve, which lies in a groove on its superior sur- face, enters the meatus auditorius interims, and at the bottom of the meatus divides into two branches, cochlear and vestibular. The distribution of these branches will be found described with the anatomy of the internal ear. The auditory nerve is soft and pulpy in texture, and receives in the meatus auditorius several filaments from the facial nerve. CRANIAL NERVES. 552 Fig. 326.—1. Posterior auricular artery. 2. Temporal artery. 3. Occipital artery. 4. Glosso-pharyngeal nerve. 5, 5. Spinal accessory nerve. 6, 6. Pneumogastric nerve. 7. Sterno-mastoid (cut). 8. Facial artery. 9. Hypoglossal nerve, with communication from second cervical nerve. 10. Lower end of ditto, n. Superior cervical ganglion. 12. Digastricus. 13. Third cervical nerve. 14. Superior laryngeal nerve. 15. Internal carotid. 16. Thyro-hyoid muscle. 17. External carotid. 18. Common carotid. 19. Fourth cervical nerve. 20. Inferior constrictor of pharynx. 21. Phrenic nerve. 22. Crico-thyroid. 23. Middle cervical ganglion. GLOSSO-PHARYNGEAL NERVE. 553 24. Trachea. 25. Thyroid axis. 26. Recurrent laryngeal nerve. 27. Subclavian artery. 28. Innominate artery. 29. (Esophagus. 30. Vena cava superior (cut). 31. Gangliated cord of sympathetic. 32. Posterior pulmonary plexus. 33. Phrenic, nerve (cut). 35. (Esophageal plexus. 37. Vena azygos major. 39. Thoracic duct. 41. Thoracic aorta. 43. Great splanchnic nerve. The glosso-pharyngeal nerve, as its name implies, is the nerve of sensation of the mucous membrane of the tongue and pharynx, but it also gives branches to some of the muscles of these organs. It arises by five or six filaments from the groove between the olivary and restiform bodies, and escapes from the skull at the innermost extremity of the jugular foramen through a distinct opening in the dura mater, lying anteriorly to the sheath of the pneumogastric and spinal accessory nerves, and internally to the jugular vein. It then passes forward between the jugular vein and internal carotid artery, and crosses the artery to reach the posterior border of the stylo- pharyngeus. Following the posterior border of this muscle for a short distance, it next passes across it and the middle constrictor and behind the hyo-glossus muscle, to be distributed to the mucous mem- brane of the tongue, pharynx, and tonsil. ‘ Deep Origin.—Beneath the floor of the fourth ventricle, above the nucleus of the vagus and below that of the auditory nerve. While in the jugular fossa, it presents two gangliform swellings : one superior, the jugular ganglion, of small size, and involving only the posterior fibres of the nerve; the other inferior, nearly half an inch below the preceding, of larger size, and occupying the whole diameter of the nerve, the petrous ganglion or ganglion of Andersch. The branches of the glosso-pharyngeal nerve are branches of communication and branches of distribution. The branches of communication proceed chiefly from the gan- glion of Andersch ; they are—one to join the auricular branch of the pneumogastric ; one to the ganglion of the root of the pneumo- gastric ; one to the superior cervical ganglion of the sympathetic ; and one, which arises below the ganglion and pierces the posterior belly of the digastricus muscle, to join the facial nerve. The branches of distribution are— NINTH NERVE. Tympanic, Carotid, Muscular, Pharyngeal, Tonsillitic, Lingual. The tympanic branch (Jacobson’s nerve) proceeds from the ganglion of Andersch, or from the trunk of the nerve immediately above the ganglion ; it enters a small bony canal between the jugular fossa and carotid foramen (p. 99), and divides into six branches, which are distributed on the inner wall of the tympanum, and establish a plexiform communication (tympanic plexus) with the sympathetic and fifth pair of nerves. The branches of distribu- tion supply the fenestra rotunda, fenestra ovalis, and Eustachian CRANIAL NERVES. 554 Fig. 327.—1. Gasserian ganglion of fifth nerve. 2. Internal carotid artery. 3. Pharyngeal branch of pneumogastric. 4. Glosso-pharyngeal nerve. 5. Lingual nerve (fifth). 6. Spinal accessory nerve. 7. Middle constrictor of pharynx. 8. Internal jugular vein (cut). 9. Superior laryngeal nerve. 10. Ganglion of trunk of pneumogastric nerve. 11. Hypoglossal nerve on hyo-glossus. 12. Ditto com- municating with vagus and first cervical nerve. 13. External laryngeal nerve. 14. VAGUS NERVE. 555 Second cervical nerve looping with first. 15. Pharyngeal plexus on inferior con- strictor. 16. Superior cervical ganglion of sympathetic. 17. Superior cardiac nerve of pneumogastric. 18. Third cervical nerve. 19. Thyroid body. 20. Fourth cervical nerve. 21, 21. Left recurrent laryngeal nerve. 22. Spinal accessory communi- cating with cervical nerves. 23. Trachea. 24. Middle cervical ganglion of sym- pathetic. 25. Middle cardiac nerve of pneumogastric. 26. Phrenic nerve (cut). 27. Left carotid artery. 28. Brachial plexus. 29. Phrenic nerve (cut). 30. Inferior cervical ganglion of sympathetic. 31. Pulmonary plexus of pneumogastric. 32. Thoracic aorta. 33. (Esophageal plexus. 34. Vena azygos minor superior. 35. Vena azygos minor inferior. 36. Grangliated cord of sympathetic. tube : those of communication join the carotid plexus in the carotid canal, the petrosal branch of the Vidian nerve (great petrosal nerve), and lesser petrosal nerve. The carotid branches are several filaments which follow the trunk of the internal carotid artery, and communicate with the nervi molles of the sympathetic and pharyngeal branch of the pneumogastric. The muscular branch divides into filaments, which are distri- buted to the stylo-pharyngeus, and constrictor muscles. The pharyngeal branches are two or three filaments which are distributed to the pharynx and unite with the pharyngeal branches of the pneumogastric, external laryngeal, and sympathetic nerves to form the pharyngeal plexus. The tonsillitic branches proceed from the glosso-pharyngeal nerve, near its termination; they form a plexus (circulus tonsil- laris) around the base of the tonsil, from which numerous filaments are given off to the mucous membrane of the fauces and soft palate. These filaments communicate with the descending palatine branches of Meckel’s ganglion. The lingual branches enter the substance of the tongue beneath the hyo-glossus and stylo-glossus muscle, and are distributed to the mucous membrane of the side and base of the tongue, and to the epiglottis and fauces. The pneumogastric or vagus nerve is the nerve of the re- spiratory organs and upper part of the alimentary canal, supplying branches to the larynx, trachea, lungs, pharynx, oesophagus, and stomach, and also giving branches to the heart. It arises by ten or fifteen filaments from the groove between the olivary and restiform bodies, immediately below the glosso-pharyngeal, and passes out of the skull through the inner extremity of the jugular foramen, enclosed in a sheath of dura mater common to it and the spinal accessory. The nerve then takes its course down the side of the neck, lying at first between the internal jugular vein and internal carotid artery, and lower down behind and between that vein and the common carotid artery and enclosed in the same sheath. At the root of the neck the course of the nerve on the two sides is different. The right nerve enters the chest by passing between the subclavian artery and vein, and descends by the side of the trachea to the pos- terior part of the root of the right lung ; it then proceeds as a double cord along the posterior aspect of the oesophagus to the corresponding TENTH NERVE 556 CRANIAL NERVES. side of tlie stomach ; the two cords reuniting at the lower part of the oesophagus. The left nerve enters the chest between the left common carotid and subclavian artery lying behind the left vena innominata ; it then crosses the arch of the aorta, and reaches the posterior part of the root of the left lung, whence it descends, by one or two cords, along the anterior aspect of the oesophagus to the front part of the stomach. In the jugular foramen, the pneumogastric nerve presents a small round ganglion, the superior ganglion or ganglion of the root; and immediately after its exit a gangliform swelling, nearly an inch in length, the inferior ganglion or ganglion of the trunk. Deep Origin.—The fibres of origin of the pneumogastric nerve may be traced to a mass of nerve cells placed beneath the floor of the fourth ventricle, below the nucleus of the glosso-pharyngeal, and extending down to the calamus scriptorius. The branches of the pneumogastric nerve are brandies of com- munication and branches of distribution. The branches of communication proceed from the ganglia; from the superior ganglion one or two branches pass to the spinal accessory ; one or two to the superior ganglion of the sympathetic ; and one to the inferior ganglion of the glosso-pharyngeal. From the inferior ganglion there pass off branches to the hypoglossal, branches to the superior cervical ganglion of the sympathetic, and branches to the loop between the first and second cervical nerve. The branches of distribution are— Meningeal, Auricular, Pharyngeal, Superior laryngeal, Cardiac, Inferior or recurrent laryngeal. Anterior pulmonary, Posterior pulmonary, (Esophageal, Gastric. The meningeal or recurrent is a small branch given off from the ganglion of the root; it passes backwards to be distributed to the dura mater of the posterior fossa of the skull. The auricular branch (Arnold’s nerve) is given off from the lower part of the ganglion of the root, or from the trunk of the nerve immediately below it, and receives immediately after its origin a small branch of communication from the petrous ganglion of the glosso-pliaryngeal. It then passes outwards behind the jugular vein, and at the outer side of that vessel enters a small canal (p. 99) in the jugular fossa of the temporal hone. Guided hv that canal it reaches the descending part of the aqueduct us Fallopii and communicates with the facial nerve ; it then passes outwards through a small fissure situated between the mastoid process and external auditory process (auditory fissure), and reaching the surface of the hone communicates with the posterior auricular nerve and is distributed to the back part of the pinna and auditory canal. The pharyngeal nerve arises from the upper part of the ganglion VAGUS NERVE. 557 of the trunk, and crosses behind the internal carotid artery to the upper border of the middle constrictor, upon which it forms the pharyngeal plexus assisted by branches from the glosso-pharyngeal, superior laryngeal, and sympathetic. One small branch, called, the lingual branch of the vagus, is derived from the pharyngeal branches of this nerve and the glosso-pharyn-, geal; it joins the hypo- glossal nerve, as that trunk winds round the occipital artery, and is distributed with it. The pharyngeal plexus is distributed to the muscles and mucous membrane of the pharynx. The superior laryn- geal nerve arises from the ganglion of the trunk, and descends behind the internal carotid artery to the opening in the thyro- hyoid membrane, through which it passes with the superior lar- yngeal artery, and is distributed to the mucous membrane of the larynx, communi- cating with the inferior laryngeal nerve. Be- hind the internal caro- tid it gives off the external laryngeal branch, which sends a twig to the pharyngeal plexus, and then de- scends to supply the inferior constrictor, crico - thyroid muscle and thyroid gland. This branch communicates inferiorly with the superior cardiac nerve and superior cervical ganglion of the sympathetic. Fig. 328. — Origin and distribution of the glosso-pharyn- geal, pneumogas- tric, and spinal accessory nerves. 1, 3, 4. Medulla oblongata. 1. An- terior pyramid. 2. Pons Varolii. 3. Olivary body. 4. Restifovm body. 5- Facial nerve. 6. Origin of the glosso-pharyngeal. 7. Ganglion of An- dersch. 8. Trunk of the nerve. 9. Spinal accessory nerve. 10. Gan- glion of the root of the pneumogas- tric. 11. Ganglion of the trunk. 12. Trunk. 13. Pha- ryngeal branch forming the pha- ryngeal plexus (14) assisted by a branch from the glosso - pharyngeal (8), and one from the superior laryn- geal nerve (15). 16. Cardiac branches. 17. Recurrent la- ryngeal branch. 18. Anterior pul- monary and car- diac branches. 19. Posterior pulmo- nary branches. 20. (Esophageal plex- us. 21. Gastric branches. 22. Ori- gin of the spinal ac- cessory nerve. 23. Branch to the ster- no-mastoid mus- cle. 24. Branches to the trapezius. 558 CRANIAL NERVES. The cervical cardiac branches, two or three in number, arise from the upper and lower part of the cervical portion of the nerve. Those from above communicate with cardiac branches of the sympathetic. One large branch (inferior cardiac) is given off just before the nerve enters the chest; on the right this branch descends by the side of the arteria innominata to the deep cardiac plexus ; on the left it passes in front of the arch of the aorta to the superficial cardiac plexus. One or two cardiac branches also proceed from the thoracic portion of the right pneiunogastric nerve and end in the deep cardiac plexus. The inferior, or recurrent larnygeal nerve, curves around the subclavian artery on the right, and the arch of the aorta on the left side. It ascends in the groove between the trachea and oesophagus, and piercing the lower fibres of the inferior constrictor muscle enters the larynx close to the articulation of the inferior cornu of the thyroid with the cricoid cartilage. It is distributed to all the muscles of the larynx, with the exception of the crico-thyroid, and communicates with the superior laryngeal nerve. As it curves around the subclavian artery and aorta it gives branches (cardiac) to the deep cardiac plexus and root of the lungs ; and as it ascends the neck it distributes filaments to the oesophagus and trachea, and communicates with the external laryngeal nerve and sympathetic. The anterior pulmonary branches, two or three in number, are distributed upon the anterior aspect of the root of the lungs, form- ing, with branches from the cardiac plexuses, the anterior pulmonary plexus. The posterior pulmonary branches, more numerous and larger than the anterior, are distributed on the posterior aspect of the root of the lungs ; they are joined by filaments from the third and fourth thoracic ganglia of the sympathetic, and form the posterior pulmonary plexus. (Esophageal branches are given off by the pneumogastric nerves above the root of the lungs ; below that point, the trunks of the nerves, divided into several cords, form a plexus around the oeso- phagus, the right and left nerves communicating with each other. This plexus accompanies the oesophagus to the stomach, and is the cesopliageal plexus (plexus guise). The gastric branches are the terminal filaments of the pneumo- gastric nerves ; they are spread out upon the anterior and posterior surface of the stomach, and are likewise distributed to the omen- tum, spleen, pancreas, liver, and gall-bladder. The branches of the anterior aspect of the stomach proceed from the left nerve and com- municate with the hepatic plexus in the lesser omentum ; those of the posterior aspect are derived from the right nerve and com- municate with the solar plexus. SPINAL ACCESSORY NERVE. 559 ELEVENTH NERVE. SPINAL ACCESSORY NERVE.—The spinal accessory consists of a spinal and an accessory portion; the former arises by several filaments from the side of the spinal cord as low down as the fifth or sixth Fig. 329.—Diagram of the ninth, tenth, eleventh, twelfth, and sympathetic nerves. 1. Facial nerve. 2. Glosso-pharyngeal nerve, with its petrous ganglion. 3. Pneumogastric nerve. 4. Spinal accessory nerve. 5. Hypoglossal nerve. 6. Superior cervical ganglion of sympathetic. 7. Loop between first and second cervical nerves. 8. Carotid branch of sympathetic. 9. Tympanic nerve (Jacob- son). 10. Its branch to carotid plexus. 11. Its branch to Eustachian tube. 12. Its branch to fenestra ovalis. 13. Its branch to fenestra rotunda. 14. Its union with small super- ficial petrosal nerve. 15. Its union with large super- ficial petrosal nerve. 16. Otic ganglion. 17. Auri- cular branch of pneumo- gastric (Arnold’s nerve). 18. Junction of pneumo- gastric with spinal ac- cessory. 19. Junction of hypoglossal and first cer- vical nerve. 20. Junction of mastoid branch of spinal accessory and second cer- vical nerve. 21. Pharyn- geal plexus. 22. Superior laryngeal nerve. 23. Ex- ternal laryngeal nerve. 24. Middle cervical gan- glion of sympathetic. 2s. Junction of digastric nerve (seventh) with glosso- pharyngeal. cervical nerve, and ascends behind the ligamentum denticulatum, and between the anterior and posterior roots of the spinal nerves, 560 CRANIAL NERVES. to the foramen lacerum posterius. It communicates in its course with the posterior root of the first cervical nerve, and entering the skull by the foramen magnum, leaves it again by the jugular foramen, and becomes applied against the posterior aspect of the ganglion of the trunk of the pneumogastric, being contained in the same sheath of dura mater. The accessory portion arises from the lateral aspect of the medulla, immediately below the vagus ; its fibres being traceable through the medulla to a grey nucleus in the lower part of the floor of the fourth ventricle. The two portions lie together, in the same compartment of the jugular foramen as the vagus, and often become intimately united so as to form a short trunk. Immediately after leaving the foramen the accessory portion of the nerve joins the ganglion of the trunk of the vagus, and probably endows that nerve with motor power. The spinal portion is continued downwards behind, but sometimes in front of, the internal jugular vein, to the upper and deep part of the sterno-mastoid, pierces that muscle obliquely, and descends across the posterior triangle of the neck to the deep surface of the trapezius, to which it is distributed, its branches being continued downwards to near the lower border of the muscle. In the substance of the sterno-mastoid it communicates with branches of the cervical plexus, and in the posterior triangular space with the third and fourth cervical nerves. TWELFTH NERVE. HYPOGLOSSAL NERVE.—The hypoglossal is a nerve of motion, distributed to all the extrinsic muscles of the tongue, the genio-hyoid and the thyro-hyoid. It arises from the groove between the anterior pyramid and olivary body by ten or fifteen filaments, which are col- lected into two bundles, and escape from the cranium through the anterior condylar foramen. At its exit from the cranium, the nerve lies behind the internal carotid artery and internal jugular vein, then passing forward between the artery and vein it descends to a point parallel with the angle of the lower jaw. It next curves forward around the occipital artery, with which it forms a loop, and crossing the external carotid and lower part of the hyo-glossus muscle to the genio-hyo-glossus, sends filaments onwards with the anterior fibres of that muscle as far as the tip of the tongue. While resting on the hyo-glossus muscle it is flattened, and be- neath the mylo-hyoid communicates with the lingual branch of the fifth nerve. At its origin, the hypoglossal nerve sometimes communicates with the posterior root of the first cervical nerve. Its deep origin may be traced to one of the nuclei of grey substance, in the floor of the fourth ventricle, where it decussates with its fellow of the oppo- site side. HYPOGLOSSAL NERVE. 561 The branches of the hypoglossal nerve are—branches of communi- cation and branches of distribution. The branches of communication of the hypoglossal nerve are— several to the pneumogastric, with which nerve it is closely united ; one or two with the superior cervical ganglion of the sympathetic ; and one or two with the loop between the first and second cervical nerves. The branches of distribution are— Descendens cervicis, Thyro-hyoid, Muscular. Tbe descendens cervicis (descendens noni) is a long and slender nerve, which quits the hypoglossal just as it is about to form its arch around the occipital artery, and descends on the sheath of the carotid vessels. Just below the middle of the neck it forms a loop (ansa hypoglossi) with the communicans cervicis, derived from the second and third cervical nerves. From the convexity of this loop branches are sent to the sterno-hyoid, sterno-thyroid, and both Fig. 330.—Anatomy of the side of the neck, showing the nerves of the tongue. 1. Temporal hone. 2. Stylo- hyoid muscle. 3. Stylo-glossus. 4. Stylo-pharyngeus. 5. Tongue. 6, 18. Hyo-glossus muscle. 7. Genio-hyo- glossus. 8. Genio-hyoid. 9. Sterno- hyoid muscle. 10. Sterno-thyroid. 11. Thyro-hyoid, upon which the thyro-hyoid branch of the hypoglossal nerve is seen ramifying. 12. Omo- hyoid crossing the common carotid artery (13) and internal jugular vein (14). 15. External carotid giving off its branches. 16. Internal carotid. 17. Lingual branch of fifth giving a twig to the submaxillary ganglion (18), and communicating a little far- ther on with the hypoglossal nerve. 19. Submaxillary, or Wharton’s duct, passing forwards to the sublingual gland. The submaxillary ganglion is the small round body between figures 18 and 19. 20. Glosso-pharyn- geal nerve. 21. Hypoglossal nerve curving around the occipital artery. 22. Descendens cervicis nerve, form- ing a loop with (23) the communicans cervicis, which is seen arising by filaments from the upper cervical nerves. 24. Pneumogastric nerve. 25. Facial nerve. bellies of the omo-hyoid ; sometimes also a twig is given off to the cardiac plexus, and occasionally one to tlie phrenic nerve. The descendens cervicis probably arises from the upper cervical nerves, and is only temporarily associated with the hypoglossal (Luschka) ; this view receives confirmation from the fact that in 562 SPINAL NERVES. some instances it accompanies the vagus instead of the hypoglossal, and in others is absent, the entire distribution taking place through the communicans cervicis. In yet another set of cases, the de- scendens supplies the place of the communicans, which is otherwise unrepresented. The thyro-hyoid nerve is a small branch distributed to the thyro- hyoid muscle. It is given off by the trunk of the hypoglossal near the posterior bolder of the hyo-glossus, and descends obliquely over the great cornu of the os hyoides. According to Holl, this nerve is really derived from the upper cervical nerves. The muscular branches are given off where the nerve is covered by the mylo-hyoid muscle, and rests on the hyo-glossus ; several large branches take their course across the fibres of the genio-hyo-glossus to reach the substance of the tongue. They are distributed to the hyo-glossus, genio-hyoid, genio-hyo-glossus, and stylo-glossus muscles. On the hyo-glossus muscle, the branches of the hypoglossal nerve communicate with those of the lingual branch of the fifth nerve. SPINAL NERVES. There are thirty-one pairs of spinal nerves, each arising by two roots, an anterior or motor root, and a posterior or sensory root. The anterior roots proceed from the anterior lateral sulcus, which marks the division of the anterior from the posterior part of the antero-lateral column of the spinal cord, and gradually approach towards the anterior median fissure as they descend. The posterior roots, more regular than the anterior, proceed from the posterior lateral sulcus ; they are larger, and the filaments of origin more numerous than those of the anterior roots ; and in the intervertebral foramina there is a ganglion on each of their roots. The first cervical nerve forms an exception to these characters ; its posterior root is smaller than the anterior ; it often joins, in whole or in part, the spinal accessory nerve, and sometimes the hypoglossal; it has frequently no ganglion, and when the ganglion exists, it is often situated within the dura mater, the latter being the usual position also of the ganglia of the last two pairs of spinal nerves. After the formation of a ganglion, the two roots unite, and con- stitute a spinal nerve, which escapes through the intervertebral foramen, and separates into an anterior division for the supply of the front aspect of the body, and a posterior division for the poste- rior aspect. In the first cervical, last sacral, and coccygeal nerve this division takes place within the dura mater ; and in the upper four sacral nerves, externally to that cavity, but within the sacral canal. The anterior cords, with the exception of the first two cervical nerves, are larger than the posterior ; an arrangement which is pro- portioned to the larger extent of surface they are required to supply. SPINAL NERVES. 563 Both divisions are compound—that is to say, they contain both motor and sensory filaments. The spinal nerves are classed as follows :— Cervical 8 pairs Dorsal 12 „ Lumbar 5 „ Sacral 5 „ Coccygeal . . . . 1 „ The cervical nerves pass off transversely from the spinal cord ; the dorsal are oblique in direction ; the lumbar and sacral, vertical; Fig. 331.—Part of the cervical portion of the spinal cord, viewed on its posterior aspect; showing its membranes and the roots of the spinal nerves. 1, 1. Posterior median fissure. 2, 2. Posterior roots of the cervical nerves; on the opposite side the corresponding roots are cut through near their origin. 3, 3. Liga- mentum denticulatum. 4. Spinal accessory nerve, ascending between the posterior roots and ligamentum denticulatum. 5, 5. Dura mater. 6, 6. Openings in the dura mater for the passago of the roots of the nerve. 7, 7. Ganglia on the posterior roots. 8. Anterior roots. The posterior roots have been cut away in order to show each anterior root proceeding to join the nerve beyond the ganglion. Fig. 332.—Roots of the spinal nerves. 1. Anterior root. 2. Posterior root. 3. Anterior division. 4. Posterior division. 5. Ganglion on the posterior root. the latter form the large assemblage of nerves, at the termination of the cord, called cauda equina. The cauda equina occupies the lower third of the spinal canal. Point of Exit of the Spinal Nerves.—The roots of the spinal nerves run obliquely downwards from the part of the cord from which each springs to the intervertebral foramen by which it emerges from the canal. The degree of obliquity varies in different regions, being greatest in the lumbar and sacral nerves, and least in the dorsal. The following table from A. Macalister’s Text-Book of 564 CERVICAL NERVES. Anatomy gives tlie relation of the point of origin of each nerve to the bodies and tips of the spinous processes of tlie vertebrae :— Level of Body of No. of Nerve. Level of Tip of Spine of Level of Body of No. of Nerve. Level of Tip of Spine of C I C i D 8 9 7 d 2 9 IO 8 d 2i 3 I c IO ii 9 d 3 4 2 C 12 IO d 4 5 3 c ii L i Ii d 5 6 4 c ... f 2 6 7 Sc 3 | 12 d 7 D i 7 c ... i 4 D i 2 i d f 5 2 3 S i ... 3 4 2 d 2 y 4 5 3 d 3 5 6 4 d i 4 j 11 6 7 5 d 5 i 7 8 6 d C i l L 2 CERVICAL NERVES. The cervical nerves increase in size from the first to the fifth, and then remain the same size to the eighth. The first (suboccijntal) passes out of the spinal canal between the occipital bone and atlas ; the second between the posterior ring of the atlas and the lamina of the axis ; and the last between the last cervical and first dorsal vertebra. Each nerve, at its escape from the intervertebral foramen, divides into an anterior and a posterior division. The anterior divisions of the four upper cervical nerves form the cervical plexus ; the posterior divisions, the posterior cervical plexus. The anterior divisions of the four inferior cervical together with the first dorsal form the brachial plexus. ANTERIOR CERVICAL NERVES.—Tlie anterior division of the first cervical or suboccipital nerve escapes from the spinal canal through the groove on the posterior arch of the atlas, which supports the vertebral artery, lying beneath that vessel. It descends in front of the transverse process of the atlas, sends twigs to the occipito- atlantal joint, rectus lateralis and rectus anticus minor, and forms an anastomotic loop by communicating with an ascending branch of the second nerve. Branches from this loop communicate with the pneumogastric nerve, hypoglossal nerve, and superior cervical ganglion of the sympathetic. Tlie anterior cord of the second cervical nerve, at its exit from the intervertebral foramen between the atlas and axis, gives twigs to the rectus anticus major, scalenus medius, and levator anguli scapulae, and divides into three bran ches : ascending branch, which CERVICAL PLEXUS. 565 completes the arch of communication with the first nerve ; and two descending branches, which form loops with corresponding branches of the third nerve. The anterior cord of the third cervical nerve, double the size of the preceding, divides at its exit from the invertebral foramen into several branches, some of which are distributed to the rectus major, longus colli, and scalenus medius, while others communicate and form loops with the second and fourth nerves. The anterior cord of the fourth cervical nerve, equal in size with the preceding, sends twigs to the rectus major, longus colli, and leva- tor anguli scapulae, communicates with the third, and sends a small branch downwards to the fifth nerve. Its principal branches pass downwards and outwards across the posterior triangle of the neck, towards the clavicle and acromion. The anterior cords of the fifth, sixth, seventh, and eighth cervical nerves will be described with the brachial plexus, of which they form a part. CERVICAL PLEXUS.—The cervical plexus is constituted by loops of communication between the anterior divisions of the first four cervical nerves. The plexus iests on the levator anguli scapulae, posterior and middle scalenus, and splenius colli muscle, and is covered by the sterno-mastoid and platysma. The branches of the cervical plexus may be arranged into super- ficial and deep Superficialis colli, Auricularis magnus, Occipitalis minor. Superficial . . Ascending, Descending, Acromial, Clavicular, Sternal. Communicating branches, Communicans cervicis, Muscular, Phrenic. Deep The superficialis colli is formed by communicating branches from the second and third cervical nerves ; it curves around the posterior border of the sterno-mastoid, and crosses obliquely behind the external jugular vein to the anterior border of that muscle, where it pierces the deep cervical fascia and divides into an ascending and a descending branch. The ascending branch passes upwards to the submaxillary region, and divides into four or five filaments, some of which pierce the platysma myoides, and supply the integument as high as the chin and lower part of the face; while others form a plexus with the inframaxillary branches of the facial nerve beneath the platysma. One or two filaments from this branch accompany the external jugular vein. The descending branch pierces the platysma, and is distributed to 566 CERVICAL NERVES. the integument of the front of the neck as far downwards as the sternum. The auricularis magnus, the largest of the three ascending branches of the cervical plexus, also proceeds from the second and third cervical nerves ; it curves around the posterior border of the sterno-mastoid, and ascends upon that muscle, lying parallel with the external j ugular vein, to the parotid gland, where it divides into an anterior and a posterior branch. The anterior branch is distributed to the integument over the paro- tid gland, and to the gland itself, communicating with the facial nerve. The posterior branch ascends behind the ear, where it divides into auricular branches, supplying the pinna ; and a mastoid branch which communicates with the posterior auricular branch of the facial and is distributed to the integument behind the ear. The auricular branches communicate with the auricular offsets of the facial nerve, pneumogastric nerve, and occipitalis minor. The occipitalis minor arises from the second cervical nerve; it curves around the posterior border of the sterno-mastoid above the preceding, and ascends upon that muscle, parallel with its poste- rior border, to the lateral and posterior aspect of the cranium. It is distributed to the integument, to the occipital portion of the occipito-frontalis and attollens auriculam, and communicates with the occipitalis major, auricularis magnus, and posterior auricular branch of the facial. Superficial Descending Branches.—The acromial and clavicu- lar are two or three large nerves which proceed from the fourth cervical nerve, and pass downwards in the posterior triangle of the neck ; they pierce the dee]) fascia, and crossing the clavicle are dis- tributed to the integument of the front of the chest as low down as the nipple line, from the sternum to the acromion ; hence their designation, clavicular and acromial. The most anterior of the branches is named sternal, from its destination, and the outermost branch passes over the clavicular attachment of the trapezius, to reach the shoulder. Deep Branches.—The communicating branches are filaments which arise from the loop between the first and second cervical nerves, and pass inwards to communicate with the sympathetic, pneumogastric, and hypoglossal nerves. The first three cervical nerves send branches to the first cervical ganglion ; the fourth sends a branch to the trunk of the sympathetic, or to the middle cervical ganglion. From the second cervical nerve a large branch is given off, which joins the spinal accessory nerve. The communicans cervicis (communicans noni) is a long and slender branch of communication between the cervical plexus and descendens cervicis; it is formed by filaments from the second and third cervical nerves, descends at the outer side of the internal jugular vein, and forms a loop with the descendens cervicis over the sheath of the carotid vessels. The muscular branches of the cervical plexus are distributed PHRENIC NERVE. 567 to tlxe muscles of the front of the vertebral column and side of the neck. From the loop, between the first and second nerve, branches are given to the anterior recti; from the second cervical nerve a branch proceeds to the sterno-mastoid; from the third and fourth nerve branches are distributed to the trapezius, levator anguli scapulae, scalenus medius, and scalenus posticus. The branch to the trapezius communicates with the spinal accessory nerve. The phrenic nerve (internal respiratory of Bell) is formed by the union of filaments from the fourth and fifth cervical nerves, and is joined by a communication from the combined cord of the fifth and sixth and a filament from the sympathetic. It descends to the root of the neck, resting on the scalenus anticus muscle, crosses the first portion of the subclavian artery, and enters the chest between it and the subclavian vein, passing over the com- mencement of the internal mammary artery. Within the chest it passes downwards through the middle mediastinum, lying between the pleura and pericardium, and in front of the root of the lung, to the diaphragm ; near the diaphragm it divides into branches which pierce that muscle, and are distributed on its under surface. Some of its filaments reach the abdomen through the openings for the oesophagus and vena cava, and communicate with the phrenic and solar plexus, and on the right side with the hepatic plexus. The left phrenic nerve is longer than the right, from the inclination of the heart to the left side, and crosses the arch of the aorta. The right nerve is situated more deeply in the upper part of the chest than the left, and lies in contact with the right innominate vein and superior vena cava; at its termination it forms a plexus with branches derived from the solar plexus, and in this there is usually a small ganglion (phrenic ganglion). Each nerve is accompanied by the arteria comes nervi phrenici, a branch of the internal mammary, and by two veins. POSTERIOR CERVICAL NERVES.—The posterior divisions of the cervical nerves issue from between the tranverse processes, and divide into an internal and external branch. The internal branch is directed inwards towards the middle of the spine, and, becoming cutaneous near the spinous processes of the vertebrae, is then re- flected outwards to supply the integument. The external branch, smaller than the internal, is distributed to the muscles of the outer portion of the vertebral groove. The posterior division of the first cervical nerve (suboccipital), larger than the anterior, escapes from the spinal canal through the opening for the vertebral artery, lying posteriorly to that vessel, and emerges in the suboccipital triangle. It is distributed to the recti, obliqui, and complexus, and sends a branch downwards to com- municate with the second cervical nerve ; it has no external branch. The posterior cord of the second cervical nerve is three or four- times larger than its anterior cord, and exceeds in size the other posterior cervical nerves. Its internal branch is the occipitalis major nerve. 568 CERVICAL NERVES. The posterior cord of the third cervical nerve is smaller than the second, but larger than the fourth ; its internal branch gives off a cutaneous branch to the back of the cranium. The posterior cords of the remaining cervical nerves go on pro- gressively decreasing in size to the seventh. The internal branches of the second, third, fourth, and fifth nerves lie on the semispinalis colli muscle, and are closely connected with a fascia which separates that muscle from the complexus. The second and third, with a branch from the first, constitute the pos- terior cervical plexus ; and all the branches in their course to the surface pierce the complexus and trapezius, and some the splenius. The internal branches of the sixth, seventh, and eighth nerves pass beneath the semispinalis colli, which they supply, as they also do the interspinales, multifidus spinse, and complexus ; finally they send twigs through the latter muscle to supply the skin over the spinous processes of the lower cervical vertebrae. The occipitalis major nerve, the internal branch of the posterior cord of the second cervical nerve, ascends obliquely inwards be- tween the obliquus inferior and complexus, pierces the complexus and trapezius after passing for a short distance between them, and ascends the posterior aspect of the head in company with the occi- pital artery. Soon after its escape from the trapezius, it receives a branch from the third cervical, and divides into numerous branches, which are distributed to the occipitalis muscle and to the integu- ment as far as the summit of the head. It communicates with the occipitalis minor nerve, and sends an auricular branch to the back of the ear. BRACHIAL PLEXUS. Tlie brachial or axillary plexus of nerves is formed by communi- cations between the anterior divisions of the four lower cervical nerves and first dorsal. These nerves are alike in size, and their mode of disposition in the formation of the plexus is as follows : the fifth and sixth unite to form a common trunk, tlie eighth and first dorsal unite in like manner, the seventh runs alone ; each of these three trunks then divides into an anterior and posterior branch. The anterior branch of the trunk derived from the fifth and sixth receives the anterior branch of the seventh, and these together form the outer cord. The anterior branch of the trunk formed by the eighth and first dorsal constitutes the inner cord. The three pos- terior branches unite to form the posterior cord. The plexus is broad in the neck, narrows as it descends into the axilla, and again enlarges at its lower part, where it divides into its terminal branches. The brachial plexus communicates with the cervical plexus by means of a branch from the fourth to the fifth nerve, and receives branches from the two inferior cervical ganglia of the sympathetic. The plexus is in relation in the neck with the scaleni muscles; BRACHIAL PLEXUS. 569 lower down it is placed between the clavicle and subclavius muscle above, and the first rib and first serration of the serratus magnus muscle below. In the axilla, it is situated at first to the outer side of and then behind the axillary artery, resting by its outer border against the tendon of the subscapularis muscle. Lower down it completely surrounds the artery. The branches of the brachial plexus are: from the outer cord, one of the anterior thoracic nerves, the musculo-cutaneous nerve, and the outer head of the median ; from the inner cord, the other anterior thoracic nerve, inner head of the median, internal cutaneous, lesser internal cutaneous of Wrisberg, and ulnar ; from the posterior cord, the subscapular nerves, circumflex, and musculo-spiral. Besides these, the brachial plexus, while in the neck, gives off several superior muscular branches: one to the subclavius muscle, Fig. 333.—Nerves forming the bra- chial plexus. The numerals 5, 6, 7, 8, and 1, refer to the four lower cervical and first dorsal nerves. R. Nerve to the rhom- boid muscles. Ft. Posterior or long thoracic. Ss. Supra-scapu- lar. Sc. Nerve to the subclavius. Uss. Upper subscapular. Lss. Long subscapular. Iss. Inferior subscapular. Rat. External an- terior thoracic. Iat. Internal anterior thoracic. Me. Musculo- cutaneous. M. Median. Ms. Musculo-spiral. U. Ulnar. Ic. Internal cutaneous. Lie. Lesser internal cutaneous. *** Ante- rior and (ttt) posterior branches of the three primary trunks. C. Circumflex. one to the rhomboid muscles and levator anguli scapulae; one of large size, the suprascapular; and a long and slender nerve which passes down the thoracic wall of the axilla, the posterior thoracic or external respiratory nerve of Bell. The spinal nerves with which each of the nerves of the brachial plexus is connected are shown in the subjoined table ; the higher numbers refer to the cervical nerves, the unit to the dorsal nerve:— Subscapular Circumflex Musculo-spiral Ulnar .... 8,1, or 7,8,1. from 5, 6, 7, 8. Internal cutaneous Lesser internal cutaneous . . 8, 1. External cutaneous Median 5, 6, 7, 8, 1. Anterior thoracic 5, 6, 7, Outer 5, 6, 7. Inner 8, 1. 570 BRACHIAL PLEXUS. The anterior thoracic nerves, two in number, proceed, one from the external cord of the plexus, the other from the internal cord. The former, the external or superficial branch, crosses the axillary artery in the space above the pectoralis minor to the front of the chest, and is distributed to the pectoralis major muscle. The Fig. 334.—The nerves of the axilla. 1. Scalenus mcdius. 2. Scalenus anticus. 3. Cord formed by fifth and sixth cervical nerves. 4. Seventh cervical nerve. 5. Suprascapular nerve. 6. Subclavian artery (cut). 7. Insertion of subclavius. 8. Cord formed by eighth cervical and first dorsal nerves. 9. Pectoralis major (reflected). 10. Internal anterior thoracic nerve. 11. External anterior thoracic nerve. 12. Origin of subclavius. 13. Pectoralis minor (reflected). 14. Internal cutaneous nerve. 15. Axillary artery (cut). 16. Posterior thoracic nerve (Bell). 17. Musculo-cutaneoua nerve. 18. Origin of pectoralis minor. 19. Median nerve. 20. Nerve of Wrisberg. 21. Coraco-bracliialis. 22. Intercosto-humeral nerve. 23. Ulnar nerve. 24. Subscapularis. 25. Brachial artery. 26. Lateral cutaneous branch of third intercostal nerve. 27. Middle subscapular nerve. 28. Short sub- scapular nerve. 29. Long subscapular nerve. 30. Pectoralis major (cut). 31. Basilic vein. 32. Serratus magnus. 33. Latissimus dorsi. internal or deeper branch issues from between the axillary artery and vein, and after forming a loop of communication with the pre- ceding is distributed to the under surface of the pectoralis minor and major, generally piercing the former to reach the latter. BRACHIAL PLEXUS. The posterior thoracic, or external respiratory of Bell, is formed by the junction of two offsets, one from the fifth, the other from the sixth cervical nerve ; it crosses behind the brachial plexus to reach the side of the chest, and descends on the serratus magnus to the lower part of that muscle, to which it is distributed. The superior muscular nerves are small branches to the longus colli and scaleni, and branches to the rhomboidei and subclavius. The rhomboid branch proceeds from the fifth cervical nerve, and passing backwards through the fibres of the scalenus medius, and beneath the levator anguli scapulae, is distributed to the under surface of the rhomboid muscles. In its course it sometimes gives a branch to the levator anguli scapulae. The subclavian branch, proceeding from the cord formed by the fifth and sixth nerve, descends in front of the subclavian artery, to the subclavius muscle. This nerve usually communicates with the phrenic at its entrance into the chest. The suprascapular nerve arises from the trunk formed by the union of fifth and sixth cervical nerves and proceeds obliquely out- wards, along with the artery of the same name, to the suprascapular notch ; it passes through the notch, crosses the supra-spinous fossa beneath the supra-spinatus muscle, and running in front of the con- cave margin of the spine of the scapula enters the infra-spinous fossa, to be distributed to the supra-spinatus and infra-spinatus muscles, and sends two or three filaments to the shoulder-joint. The subscapular nerves are three in number; one arises from the brachial plexus above the clavicle, the others from the posterior cord of the plexus within the axilla. The first or smallest supplies the upper part of the subscapularis muscle ; the second and largest (ilong subscapular) follows the course of the subscapular artery, and is distributed to the latissimus dorsi; the third supplies the lower part of the subscapularis muscle and teres major. BRACHIAL NERVES.—The brachial branches of the plexus are arranged in the following order : musculo-cutaneous, and one head of the median to the outer side of the artery ; the otlier head of the median, internal cutaneous, lesser internal cutaneous, and ulnar, to its inner side ; the circumflex and musculo-spiral behind. The MUSCULO-CUTANEOUS NERVE (external cutaneous, per- forans Casserii) arises from the brachial plexus in common with the external head of the median ; pierces the coraco-brachialis muscle, and passes between the biceps and brachialis anticus to the outer- side of the bend of the elbow, where it perforates the deep fascia, and divides into an anterior and posterior branch. These branches pass behind the median cephalic vein ; the anterior, the larger of the two, runs along the radial border of the forearm and communicates with the radial nerve on the back of the hand ; the posterior and smaller is distributed to the back of the forearm, communicating with the internal cutaneous, and distributes filaments to the syno- vial membranes of the wrist-joint. The musculo-cutaneous nerve supplies the coraco-brachialis, biceps, 572 BRACHIAL PLEXUS. and brachialis anticus in the upper arm, and the integument of the outer side of the forearm as far as the wrist and hand. It also gives a branch to the elbow-joint, and another which accompanies the nutrient artery to the interior of the humerus. The INTERNAL CUTANEOUS NERVE, one of the internal and smaller branches of the brachial plexus, arises from the plexus in common with the ulnar and internal head of the median, and passes down the inner side of the arm in company with the basilic vein, giving off several cutaneous filaments in its course. At about the middle of the upper arm it pierces the deep fascia by the side of the basilic vein and divides into two branches, anterior and posterior. The anterior branch, the larger of the two, divides into several branches which pass in front of, and sometimes behind the median basilic vein at the bend of the elbow, and descend in the course of the palmaris longus muscle to the wrist, distributing filaments to the integument in tlieir course and communicating with the anterior branch of the musculo-cutaneous on the outer side, and its own internal branch on the inner side of the forearm. The posterior branch sends off several twigs to the integument over the inner con- dyle and olecranon, passes behind the inner condyle, and descends the forearm in the course of the ulnar vein as far as the wrist, sup- plying the integument of the inner side of the forearm, and com- municating with the external branch of the same nerve in front, and the dorsal branch of the ulnar nerve at the wrist. The LESSER INTERNAL CUTANEOUS NERVE, or nerve of Wrisberg, the smallest of the brachial nerves, arises with the preceding from the inner cord of the plexus, and issuing from be- neath the axillary vein descends the inner side of the arm, to the middle of its posterior aspect, where it pierces the fascia and is dis- tributed to the integument of the lower third of the upper arm as far as the olecranon. While in the axilla, the nerve of Wrisberg communicates with the intercosto-humeral nerve, and sometimes its place is taken by the latter. It also communicates with the posterior branch of the internal cutaneous nerve. The MEDIAN NERVE, named from its median position in the arm and forearm, arises by two heads which proceed from the outer and inner cord of the plexus and embrace the axillary artery. The nerve lies at first to the outer side of the brachial artery, but crosses it in the middle, sometimes in front and sometimes behind, and getting to its inner side descends to the bend of the elbow. It next passes between the two heads of the pronator radii teres and beneath the flexor sublimis digitorum, and runs down the middle of the forearm, lying between the latter muscle and the flexor profundus to the wrist. It then dips beneath the annular ligament and enters the palm of the hand. Just above the wrist it is superficial, lying be- tween the tendons of the flexor carpi radialis and flexor sublimis digitorum. In the forearm the nerve is accompanied by a small branch of the anterior interosseous artery. The branches of the median nerve are— MEDIAN NERVE. 573 Muscular, Anterior interosseous, Superficial palmar, Digital. The muscular branches are given off by the nerve at the bend of the elbow; they are distributed to all the muscles of the anterior aspect of the forearm, with the exception of the flexor carpi ulnaris, and ulnar half of the flexor profundus. The branch to the pro- nator radii teres sends off reflected filaments to the elbow-joint. The anterior interosseous is a large branch ac- companying the anterior interos- seous artery, and supplying the deep layer of muscles and the bones of the fore- arm, being lost inferiorly in the pronator quad- ratus. From its lower end a small twig is given off to the front of the wrist-joint. The superficial palmar branch arises from the median at about the lower fourth of the forearm ; it crosses the an- nular ligament, and is distributed to the integument of the palm of the hand, and ball of the thumb. The median nerve as it enters the palm of the hand is of a Fig. 335.—Deep dis" section of the front of the forearm and hand. i. Supina- tor longus (cut). 2,2. Ulnar nerve. 3. Brachialis anticus. 4. Biceps. 5. Mus- culo-spiral nerve. 6. Median nerve. 7. Posterior inter- osseous nerve. 8. Pronator teres and flexor carpi radia- lis (cut). 9. Ex- tensor carpi radia- lis longior (cut). 10. Brachial artery. 11. Supinator bre- vis. 12. Flexor sublimis digito- rum (cut). 13, 13. Radial nerve. 14, 14. Flexor carpi ulnaris. 15. Ex- tensor carpi radia- lisbrevior. 16. Ul- narartery. 17. Ra- dial origin o (flexor sublimis digito- rum (cut). 18. Flexor profundus digitorum. 19. Tendon of prona- tor teres. 20, 20. Dorsal branch of ulnarnerve. 21,21. Radial artery. 22, 22. Deep branch of ulnar nerve. 23. Flexor longus pol- licis. 24. Abduc- tor minimi digiti. 25. Anterior inter- osseous nerve. 26. Digital branches of ulnar nerve. 27. Tendon of supina- tor longus. 28. One of the lumbricalis muscles. 29. Pro- nator quadratus. 31. Tendon of flexor carpi radia- lis. 33. Digital branches of me- dian nerve. 35. Adductor pollicis. BRACHIAL PLEXUS. 574 reddish colour and is spread out and flattened ; it divides into six branches, one muscular and five digital. The muscular branch is distributed to the abductor pollicis, flexor ossis metacarpi pollicis, and radial half of the flexor brevis pollicis. The digital branches are arranged as follows : two pass outwards to the thumb and supply its borders ; the third runs along the radial side of the index finger, sending a twig to the first lumbri- calis in its course ; the fourth subdivides for the supply of the adjacent sides of the index and middle finger, and gives a twig to the second lumbricalis ; the fifth receives a filament of communica- tion from the ulnar nerve, and supplies the collateral branches of the middle and ring fingers. Opposite the base of the first phalanx, each nerve gives off a dorsal branch which runs along the border of the dorsum of the finger. Near its extremity the nerve divides into a palmar and a dorsal branch ; the former supplying the sentient extremity of the finger, the latter the structures around and beneath the nail. The digital nerves in their course along the fingers lie to the inner side of and superficially to the arteries; and the nerve of one side of a finger has no cbmmunication with that of the opposite side. It will be observed that the median nerve supplies all the muscles of the front of the forearm except the flexor carpi ulnaris and half the flexor profundus digitorum. In the hand it gives branches to those muscles of the thumb which lie to the radial side of the tendon of the flexor longus pollicis, and the two outer lumbricales ; the latter muscles are supplied by this nerve because they are con- nected with the tendons of that portion of the flexor profundus which derives its nerve supply from the median. The digital branches are distributed to the palmar aspect of the thumb, index, middle, and half the ring fingers. The ULNAR NERVE is somewhat smaller than the median, behind which it lies, gradually diverging from it in its course. It arises from the inner cord of the brachial plexus in common with the internal head of the median and internal cutaneous nerve, and runs down the inner side of the arm, piercing the internal intermuscular septum from before backwards, to the groove between the internal condyle and olecranon, resting on the internal head of the triceps, and accompanied by the inferior profunda artery. At the elbow it is superficial, and supported by the inner condyle, against which it may be compressed, giving rise to the thrilling sensation along the inner side of the forearm and little finger, popularly ascribed to striking the “ funny bone.” It then passes between the two heads of the flexor carpi ulnaris, and descends along the inner side of the forearm, crosses the annular ligament with the ulnar artery, and divides into two branches, superficial and deep palmar. At the commencement of the middle third of the forearm it comes into relation with the artery, and lies to the ulnar side of that vessel, as far as the hand. ULNAR NERVE. The branches of the ulnar nerve are— 575 Articular, Muscular, Cutaneous, Dorsal branch, Superficial palmar, Deep palmar. The articular branches are several filaments to the elbow-joint, given off from the nerve while lying in the groove between the inner condyle and olecranon. The muscular branches are distributed to the flexor carpi ulnaris and ulnar half of the flexor profundus digitorum. The cutaneous branch proceeds from about the middle of the nerve, and descends upon the ulnar artery to the hand, giving twigs to the integument in its course. One branch from its upper part, sometimes a separate offset from the nerve and sometimes absent, pierces the fascia, and communicates with the internal cutaneous nerve. The dorsal branch passes backwards beneath the tendon of the flexor carpi ulnaris, at the lower fourth of the forearm, and divides into branches which supply the integument and two fingers and a half on the posterior aspect of the hand, communicating with the radial nerve, with which it forms an arch. The superficial palmar branch, after giving some twigs to the palmaris brevis and inner border of the hand, divides into three filaments, two of which are distributed, one to the ulnar side of the little finger, and one to the adjoining borders of the little and ring fingers, while the third, a communicating branch, joins the median nerve. The deep palmar branch passes between the abductor and flexor minimi digiti, to the deep palmar arch, supplying the muscles of the little finger, interossei, two ulnar lumbricales, adductor pollicis, and inner head of the flexor brevis pollicis. The nlnar nerve supplies in the forearm the flexor carpi ulnaris and half the flexor profundus digitorum ; in the hand it supplies all the muscles of the palm which lie to the ulnar side of the tendon of the long flexor of the thumb except the two radial lumbricales. Its cutaneous branches are distributed to one and a half fingers on the front and two and a half on the back of the hand. The MUSCULO SPIRAL NERVE, the largest branch of the brachial plexus, arises from its posterior trunk in common with the circum- flex, and, descending behind the axillary and brachial artery, winds around the humerus between the triceps and the bone, and in com- pany with the superior profunda artery, pierces the external inter- muscular septum from behind forwards to reach the space between the brachialis anticus and supinator longus, and runs thence onwards to the bend of the elbow, where it divides into two branches, radial and posterior interosseous. The branches of the musculo-spiral nerve are— Muscular, Cutaneous, Radial, Posterior interosseous. 576 BRACHIAL PLEXUS. The muscular branches are distributed to the triceps, anconeus, brachialis anticus, supinator longus, and extensor carpi radialis longior. The cutaneous branches are three in number, internal and two external. The in- ternal branch arises from the nerve in the axilla, and pierc- ing the deep fascia in the upper third of the arm on its pos- terior aspect, com- municates with the intercosto - humeral nerve, and is distri- buted to the integu- ment of the posterior aspect of the upper arm, as far as the olecranon. The external cuta- neous branches pass through the sub- stance of the external head of the triceps, and pierce the deep fascia ; one, upper, near the insertion of the deltoid, the other, lower, at about the middle of the upper arm. The upper branch follows the course of the cephalic vein, sup- plying the integu- ment of the outer and fore-part of the upper arm as far as the bend of the elbow. The lower branch passes down the outer side of the forearm, reaches the posterior aspect at about its middle, and is continued on- wards to the wrist, where it communicates with the posterior branch of the musculo-cutaneous. Fig. 336. — Dissec- tion of the mus- culo-spiral nerve and its branches. I. Triceps. 2. Brachialis anticus. 3. Supinator lon- gus. 4. Biceps. 5. Musculo - spiral nerve. 6. Musculo- cutaneous nerve. 7. Origin of exten- sor carpi radialis longior. 8,8. Radial nerve. 9. Poste- rior interosseous nerve. 10. Pro- nator radii teres. II. Origin of ex- tensor carpi radi- alis brevior. 12. Plexor carpi radi- alis. 13. Anconeus. 14. Tendon of supi- nator longus. 15. Supinator brevis. 16, 16. Tendon of extensor carpi ra- dialis longior. 17. Extensor com- munis digitorum. 18, 18. Tendon of extensor carpi ra- dialis brevior. 19, 19. Extensor se- cundi internodii pollicis. 20, 20. Extensor ossis metacarpi pollicis. 21, 21. Extensor primi internodii pollicis. The radial nerve runs along the radial side of the forearm to the commencement of its lower third ; it there passes beneath the tendon of the supinator longus, and, at about two inches above the wrist-joint, pierces the deep fascia and divides into an external and internal branch. The external branch, the smaller of the two, is distributed to the outer border of the thumb, and communicates with the posterior branch of the musculo-cutaneous nerve. The internal branch crosses the direction of the extensor tendons of the thumb, and divides into several filaments for the supply of the ulnar border of the thumb, radial border of the index finger, and adjacent borders of the index and middle fingers. It communicates above the wrist with the pos- terior branch of the musculo-cutaneous nerve, and on the back of the hand forms an arch by joining with the dorsal branch of the ulnar nerve. On the backs of the fingers the digital branches com- municate with those of the median nerve. In the upper third of the forearm the radial nerve lies beneath the bolder of the supinator longus muscle ; in the middle third it is in relation with the radial artery, lying to its outer side ; and in the lower third it quits the artery, and passes beneatli the tendon of the supinator longus to reach the back of the hand. The radial nerve is purely cutaneous in its distribution, giving no branches to muscles. The posterior interosseous nerve, somewhat larger than the radial, separates from the latter at the bend of the elbow, pierces the supinator brevis muscle and emerges from its lower border on the posterior aspect of the forearm, where it divides into branches which supply all the muscles of the posterior aspect of the forearm, with the exception of the anconeus, supinator longus, and extensor carpi radialis longior. In passing from the front to the back of the forearm it winds round the outer side of the radius, and does not pass between the two bones as the posterior interosseous artery does. One branch, longer than the rest, descends upon the interosseous membrane to the posterior part of the wrist, and forms a gangliform swelling (a common character of nerves which supply joints), from which numerous filaments are distributed to the wrist-joint and to the metacarpo-phalangeal articulations. The CIRCUMFLEX NERVE arises from the posterior cord of the brachial plexus in common with the museulo-spiral. It passes down- wards over the border of the subscapularis muscle, winds around the neck of the humerus with the posterior circumflex artery, and splits into an upper and lower division ; the upper division is con- tinued onwards beneath the deltoid, and distributed to the anterior part of that muscle, some of its branches piercing the muscular fibres and becoming cutaneous. The lower division sends a branch (remarkable for a gangliform swelling) to the teres minor, several branches to the posterior part of the deltoid, and mounting upon the border of that muscle becomes cutaneous, supplying the integu- ment over its lower half by means of several filaments. Besides its CIRCUMFLEX NERVE. 577 578 DORSAL NERVES. muscular and cutaneous branches, the trunk of the nerve gives off an articular branch, which enters the shoulder-joint at its posterior and under part. DORSAL NERVES. Tlie dorsal nerves are twelve in number at each side, the first appearing between the first and second dorsal vertebra, the last between the twelfth dorsal and first lumbar. They are smaller than the lower cervical nerves, diminish gradually in size from the first to the tenth, and then increase to the twelfth. Each nerve, as soon as it has escaped from the intervertebral foramen, separates into an anterior and posterior division ; the anterior divisions being the intercostal nerves, the posterior the dorsal branches of the dorsal nerves. The dorsal branches pass directly backwards between the trans- verse processes of the vertebrae, lying internally to the anterior costo-transverse ligament, and each nerve divides into an internal and external branch. The internal branches diminish in size from the first to the last. The six upper branches pass inwards between the semi-spinalis dorsi and multifidus spin®, and, piercing the rhomboid, trapezius, and latissimus dorsi, become cutaneous close to the spinous processes, and are then reflected outwards to supply the integument. The six lower branches are lost in the muscles of the spine. The external branches increase in size from above downwards, and make their appearance in the line of separation between the longis- simus dorsi and sacro-lumbalis. The six upper branches are dis- tributed to those muscles and the levatores costarum. The six lower, after supplying the same muscles, pierce the serratus posticus inferior and latissimus dorsi in a line with the angles of the ribs, and becoming cutaneous, are directed downwards and forwards over the side of the trunk. INTERCOSTAL NERVES.—The anterior cords of the dorsal nerves, twelve in number at each side, are the intercostal nerves. Each intercostal nerve passes outwards in the intercostal space in company with the intercostal vessels, below which it lies ; at the commencement of its course it rests on the external intercostal muscle ; farther outwards it is placed between the two planes of intercostal muscles ; beyond the middle of the rib it enters the sub- stance of the internal intercostal and reaches its inner surface, being in contact with the pleura ; finally, at the anterior extremity of the intercostal space, it crosses in front of the triangularis sterni and internal mammary vessels, and piercing the internal intercostal muscle and pectoralis major, is distributed to the integument of the front of the chest and mammary gland, under the name of anterior cutaneous. The intercostal nerve, near its origin, sends one or two filaments to the neighbouring dorsal ganglion of the sympa- thetic, and midway between the vertebral column and sternum, while situated between the intercostal muscles, gives off a lateral ABDOMINAL INTERCOSTAL NERVES. 579 cutaneous branch which pierces the external intercostal muscle and divides into an anterior and posterior twig for the supply of the integument of the side of the thorax. Abdominal Intercostals.—This description applies in full only to the six upper intercostal nerves; the six lower, with the excep- tion of the last, cross the cartilages of the ribs where the thorax is deficient and take their course between the internal oblique and transversalis muscles to the sheath of the rectus, and, after supply- ing that muscle, to the linea alba, by the side of which they reach the integument constituting the anterior cutaneous nerves of the abdomen. The first and the last intercostal nerves are exceptions to this general scheme of distribution. The first ascends over the first rib to join the brachial plexus, and gives off only a small branch, to take the usual course of the other intercostal nerves. The last or twelfth nerve lies below the last rib, and after crossing the quadratus lumborum takes its course between the internal oblique and trans- versalis muscle like the other inferior intercostals. Near its origin it sends a branch, the dorsi-lumbar, downwards to join the first lumbar nerve. The branches of the intercostal nerves are—muscular, lateral cutaneous, and anterior cutaneous. The muscular branches are small twigs distributed to the inter- costal and neighbouring muscles. The lateral cutaneous nerves, given oil from the intercostals at about the middle of the lateral half of the thorax, pierce the ex- ternal intercostal muscle and pass between the fibres of the serratus magnus above and the obliquus externus below to reach the surface. The lateral cutaneous nerve then divides into an anterior and pos- terior branch. The anterior branches are directed forwards to sup- ply the integument of the antero-lateral aspect of the trunk, some of the superior branches turning around the inferior border of the pectoralis major to the mammary gland. The posterior branches take their course backwards to supply the integument of the postero- lateral aspect of the trunk, some of the superior turning around the posterior border of the axilla to reach the integument over the lower part of the scapula and latissimus dorsi; and that from the third intercostal being distributed to the integument of the axilla and neighbouring part of the arm. The first intercostal gives off no lateral cutaneous nerve ; the lateral cutaneous branch of the second intercostal nerve will be presently described, under the name of intercosto-humeral nerve. The lateral cutaneous branch of the last intercostal nerve pierces the internal and external oblique muscle, crosses the crest of the ilium just behind the tensor vaginae femoris, and is distributed to the integument of the anterior part of the gluteal region as low down as the trochanter major. The anterior cutaneous nerves are divided according to their position into those of the thorax and those of the abdomen. Having 580 ; DORSAL NERVES. reached the surface they are reflected outwards to supply the integu- ment of the front of the trunk. The anterior cutaneous branches of Fig. 337.—The nerves of the abdominal wall. 1. Peotoralis major (cut). 2. Serratus magnus. 3. Latissimus dorsi. 4. Intercostal muscles. 5. Rectus abdominis. 6. Section of obliquus externus. 7. Obliquus interims. 8. Transversalis abdominis. 9, 9. Ninth dorsal nerve. 10, 10. Tenth dorsal nerve. 11, 11. Eleventh dorsal nerve. 12, 12. Twelfth dorsal nerve. 13. Iliac branch of ilio-hypogastric. 14. Hypogastric branch of ilio-hypogastric. 15. Inguinal branch of ilio-inguinal. 16. Ilio-hypogastric and ilio-inguinal nerves. 17. Intercosto-humeral nerve. 18. Lateral cutaneous branch of intercostal nerve. the third and fourth intercostal nerves are distributed to the mam- mary gland. The intercosto-humeral nerve is the posterior division of the LUMBAR NERVES. lateral cutaneous branch of the second intercostal nerve; after piercing the external intercostal muscle, it passes downwards into the axilla and communicates with a branch of the lesser internal cutaneous nerve of Wrisberg. It then perforates the deep fascia, and is dis- tributed to the integument of the inner and back part of the arm to about the middle, and to the integument covering the lower part of the scapula. On the back of the arm it communicates with the internal cutaneous branch of the musculo-spiral nerve. This nerve sometimes takes the place of the nerve of Wrisberg. There are five pairs of lumbar nerves, of which the first makes its appearance between the first and second lumbar vertebra ; the last between the fifth lumbar and the base of the sacrum. The anterior divisions increase in size from above downwards. They communi- cate at their origin with the lumbar ganglia of the sympathetic, and pass obliquely outwards behind the psoas magnus, or between its fasciculi, sending twigs to that muscle and to the quadratus luin- borum. In this situation each nerve divides into two branches, a superior branch which ascends to form a loop of communication with the nerve above ; and an inferior branch which descends to join in like manner the nerve below. The communications which are thus established constitute the lumbar plexus. The posterior divisions diminish in size from above downwards ; they pass backwards between the transverse processes of the corre- sponding vertebrae, and each nerve divides into an internal and ex- ternal branch. The internal branch, the smaller of the two, passes inwards to be distributed to the multifidus spinse and inter-spinales. The external branches communicate with each other by several loops, and, after supplying the deeper muscles, pierce the sacro-lumbalis to reach the integument, to which they are distributed. The exter- nal branches of the three upper lumbar nerves descend over the posterior part of the crest of the ilium, and are distributed to the integument of the gluteal region. LUMBAR PLEXUS.—The lumbar plexus is formed by the com- munications and anastomoses which take place between the anterior divisions of the four upper lumbar nerves, and between the latter and the last dorsal. It is narrow above, increases in breadth in- feriorly, and is situated between the transverse processes of the lumbar vertebrae and quadratus lumborum behind, and the psoas magnus muscle in front. The branches of the lumbar plexus are the— LUMBAR NERVES. Ilio-hypogastric, Ilio-inguinal, Genito-crural, External cutaneous, Obturator, Anterior crural. The ILIO-HYPOGASTRIC NERVE proceeds from the first lumbar 582 LUMBAR NERVES. nerve, and passes obliquely outwards between the fibres of the psoas magnus and across the quadratus lumborum to about the middle of the crest of the ilium. It then pierces the transversalis muscle, and between it and the internal oblique divides into its two terminal branches, iliac and hypogastric. The iliac branch pierces the internal and external oblique muscles close to their attachment, and a little behind the middle of the crest of the ilium ; it is distributed to the integument of the gluteal region as far down as the upper part of the hip. The hypogastric branch continues its course onwards, piercing Pig. 338. — Lumbar plexus. 1. Right gangliated cord of sympathetic. 2. Ab- dominal aorta. 3, 3. Last dorsal nerves. 4. Psoas parvus. 5. Quadratus lumbo- rum. 6. Psoas mag- nus. 7, 7. Ilio-hypo- gastric nerves. 8. Iliacus internus. 9, 9. Ilio-inguinal nerve. 10. Lumbo- sacral nerve. 11, 11. Genito - crural nerves. 12. Gluteal nerve. 13. Iliac branch of ilio-hypo- gastric nerve. 14. Sacral plexus. 15, 15, 15. External cutaneous nerves. 17. Transversalis ab- dominis. 19. Obli- quus internus. 21. Obliquus externus. 23, 23. Anterior crural nerves. 25,25. Obturator nerves. 27,27. Crural branch of genito - crural nerve. 29. Genital branch of genito- crural nerve. 31. External iliac ar- tery. 33. External abdominal ring. first the internal oblique, and just above the external abdominal ring the aponeurosis of the external oblique. It is distributed to the integument of the hypogastric region and mons pubis. The ILIO-INGUINAL NERVE, smaller than the preceding, also arises from the first lumbar nerve. It passes obliquely downwards and outwards below the ilio-hypogastric nerve, and crosses the quad- ratus lumborum and iliacus muscles to the anterior part of the crest of the ilium ; it then pierces the transversalis muscle, and between that muscle and the obliquus in tern us communicates with the ilio- hypogastric nerve. It next pierces the obliquus internus, and enters GENITO-CRURAL NERVE. 583 the inguinal canal, which it traverses, lying in front of the spermatic cord, and escapes at the external abdominal ring to be distributed to the scrotum and to the integument of the upper part of the thigh, internally to the saphenous opening; and in the female to that of the pudendum. The GENITO-CRURAL NERVE proceeds from the second lumbar and by a few filaments from the loop between it and the first. It traverses the psoas magnus from behind forwards, and runs down the anterior surface of that muscle, lying beneath its fascia, to near Poupart’s ligament, where it divides into a genital and a crural branch. The genital branch crosses the external iliac artery to the in- ternal abdominal ring, and descends along the sj)ermatic canal, lying behind the cord, to the scrotum, where it distributes twigs to the spermatic cord and cremaster muscle. In the female it gives twigs to the round ligament and external labium. At the internal abdo- minal ring this nerve sends off a branch, which, after supplying the' lower border of the internal oblique and transversalis, is lost in the integument of the groin. The crural branch, the most external of the two, descends along the outer border of the external iliac artery, and, crossing the origin of the deep circumflex iliac artery, enters the sheath of the femoral vessels in front of the femoral artery. It pierces the sheath below Poupart’s ligament, and is distributed to the integument of the anterior aspect of the thigh as far as its middle. This nerve com- municates with the middle cutaneous branch of the anterior crural nerve, and is often very small. The EXTERNAL CUTANEOUS NERVE proceeds from the second lumbar, and from the loop between it and the third. It pierces the posterior fibres of the psoas muscle and crossing the iliacus on the iliac fascia, to the anterior superior spinous process of the ilium, passes into the thigh, beneath Poupart’s ligament, where it divides into two branches, anterior and posterior. The posterior branch crosses the tensor vaginae femoris muscle to the outer and posterior aspect of the thigh, and supplies the skin as far as its middle. The anterior nerve, after passing for three or four inches down the thigh in a sheath formed by the fascia lata, becomes superficial, and divides into two branches, which are distributed to the in- tegument of the outer border of the thigh, and to the articulation of the knee. Its branches assist in the formation of the plexus patellae. The OBTURATOR NERVE is formed by a branch from the third, and another from the fourth lumbar nerve, and is distributed to the obturator externus and adductor muscles of the thigh, the hip and knee joint, the femoral and popliteal artery, and sometimes to the integument of the upper and inner part; of the leg. From its origin it takes its course among the fibres of the psoas muscle, through the angle of bifurcation of the common iliac vessels, and along the inner LUMBAR NERVES. border of the brim of the pelvis, to the obturator foramen, where it joins the obturator artery. Having escaped from the pelvis, it divides into an anterior and pos- terior branch. The anterior branch passes downwards in front of the adductor brevis, supplies that muscle together with the pectineus, gracilis, and adductor longus, and at the lower border of the latter unites with the internal cutaneous and long saphenous nerve, to form a plexus. It then passes onwards to the femoral artery, to which it distributes filaments. In its course this nerve gives off an articular branch to the liip-joint; and a cuta- neous branch, which pierces the fascia lata at the knee, communi- cates with the long saphenous nerve, and is distributed to the in- tegument of the inner side of the leg as far as its middle. The cuta- neous branch is often wanting, its place being supplied by the internal cutaneous nerve, and sometimes by the acces- sory obturator. The posterior branch pierces the obturator ex- ternus muscle, to which and to the adductor magnus it distributes branches ; it also gives off an articular branch which pierces the ad- ductor magnus muscle, and accompanies the popliteal artery to the knee-joint. The accessory obturator nerve, small and inconstant, is a High Fig. 339. — Lumbar and sacral plex- uses, with the nerves of the lower extremity, i. The first four lumbar nerves; which, with a branch from the last dor- sal, constitute the lumbar plexus. 2. The four upper sacral nerves ; which, with the last lumbar, form the sacral plexus. 3. The ilio-hypo- gastric and ilio-in- guinal nerves. 4. Genito-crural nerve. 5. External cutaneous nerve. 6. Anterior crural nerve. 7. Its mus- cular branches. 8. Middle cutaneous branches. 9, 10. Internal cuta- neous branches. 11. The long or internal saphe- nous. 12. Obtu- rator nerve. 13. Gluteal nerve, a branch of the lum- bo-sacral. 14. In- ternal pudic nerve. 15. Lesser ischiatic nerve. 16. Greater ischiatic nerve. 17. Internal popliteal nerve. 18. Ex- ternal popliteal nerve. 19. Mus- cular branches. 20. Posterior tibial nerve, dividing at 21 into the two plantar nerves. 22. External saphe- nous nerve. 23. Anterior tibial nerve. 24. Musculo- cutaneous nerve, piercing the deep fascia, and divid- ing into two cuta- neous branches for the supply of the dorsum of the foot. ANTERIOR CRURAL NERVE. 585 division of the obturator, being sometimes derived from it near its origin, and sometimes by separate filaments from the third and fourth lumbar nerves. It passes down the inner border of the psoas muscle, crosses the os pubis, and dips beneath the pectineus, where it divides into branches. One of its branches is distributed to the pectineus, another supplies the hip-joint, while a third communi- cates with the anterior branch of the obturator nerve, and when of large size constitutes its cutaneous branch. As already stated, the existence of the accessory obturator nerve is uncertain. The ANTERIOR CRURAL is the largest of the divisions of the lumbar plexus; it is formed by the union of branches from the second, third, and fourth lumbar nerves, and is distributed to the integument of the front and inner side of the thigh, leg, and foot, to all the muscles of the front of the thigh (excepting one), to the iliacus, pectineus, femoral artery, and knee-joint. Emerging from beneath the psoas, the nerve passes downwards in the groove between that muscle and the iliacus, and beneath Poupart’s ligament into the thigh, where it spreads out and divides into numerous branches. At Poupart’s ligament it is separated from the femoral artery by the breadth of the psoas muscle, which at this point is scarcely more than half an inch in diameter, and by the iliac fascia, beneath which it lies. Branches.—Within the pelvis, the anterior crural nerve gives off three or four twigs to the iliacus muscle, and a branch to the femoral artery. The latter divides into filaments which entwine about the artery, and follow its course downwards in the thigh. Below Pou- part’s ligament the crural nerve becomes flattened out, and divides into numerous branches, which may be arranged into two principal groups, superficial and deep. The separate branches of these groups are as follows :— Superficial. Middle cutaneous, Internal cutaneous. Deep. Muscular, Articular, Long or internal saplienous. The superficial branches are mainly cutaneous, but they supply motor filaments to two muscles, namely, pectineus and sartorius; the deep branches are all motor, with the exception of the long saphenous, which is purely sensory. The middle cutaneous nerve pierces the fascia lata at about three inches below Poupart’s ligament, and divides into two branches, which pass down the inner and front part of the thigh, and are distributed to the integument as low as the knee-joint. At its upper part the external branch communicates with the crural branch of the genito-crural nerve ; and below, the internal branch communicates with the internal cutaneous. One or both of these branches sometimes pierce the sartorius muscle. The internal cutaneous nerve passes inwards in front of the 586 LUMBAR NERVES. sheath, of the femoral artery, and divides into an anterior and an inner branch. Previously to its division it gives off three cutaneous filaments, which nierce the fascia near the internal saphena vein, and following the course of that ves- sel , are distributed to the integument of the inner side of the thigh as low down as the knee. The upper- most of these fila- ments passes through the sa- phenous opening, the middle be- comes subcuta- neous at about the middle of the thigh, and the lowest pierces the fascia at its lower third. The anterior branch passes down the inner side of the thigh, and pierces the fascia at its lower third, near the internal saphena vein. It then divides into two twigs, one of which continues onwards to the inner side of the knee; while the other curves outwards to its outer side, com- municating in its course with a branch of the long saphenous • nerve. The inner branch descends along the inner and posterior border of the sartorius muscle to the knee, where it pierces the fascia lata, and gives off several cutaneous twigs. It then sends a small branch of communication to the long saphenous nerve, and passes down- Fig. 340.—Nerves of the thigh. 1. Gangliated cord of sympathetic. 2. Third lum- bar nerve 3. Branches to iliacus inter- nus. 4. Fourth lumbar nerve. 5. Anterior cru- ral nerve. 6. Lumbo - sacral nerve. 7. Branch to pso- as. 8. Obturator nerve. 9. Ex- ternal cutane- ous nerve (cut). 10. Nerve to pectineus. n. Superficial di- vision of ante- rior crural nerve (cut). 12. Superficial di- vision of ob- turator nerve. 13, 13. Sartori- us muscle. 14, 14. Adductor longus. 15. Branch to rec- tus. 16. Deep division of ob- turator nerve. 17. Branches to vastus inter- nus and cru- reus. 18. Ad- ductor brevis. 19. Branch to vastus inter- nus. 20. Ad- ductor magnus. 21. Vastus ex- ternus. 22, 22. Internal saphe- nous nerve. 23. Itectus femoris. 24. Patellar branch of sa- phenous nerve. 25. Vastus in- ternus. 26. Gra- cilis. ANTERIOR CRURAL NERVE. 587 wards along the inner side of the leg, to which it is distributed. While beneath the fascia lata it aids in the formation of a plexus by uniting with branches of the long saphenous nerve and descend- ing branch of the obturator. When the latter is large the inner branch of the internal cutaneous nerve is small, and may terminate in the plexus, or merely give off a few cutaneous filaments. The long or internal saphenous nerve inclines inwards to the sheath of the femoral vessels, and passes downwards in front of the sheath and beneath the aponeurotic expansion which covers the sheath, to the opening in the adductor magnus. It then quits the femoral vessels, and continuing to descend, passes between the tendons of the sartorius and gracilis, and reaches the internal saphena vein. By the side of the latter it passes down the inner side of the leg, in front of the inner ankle, and along the inner side of the foot as far as the great toe, being distributed to the integu- ment in its course. The branches of the long saphenous nerve in the thigh are—one or two to join the plexus formed by the obturator and internal cutaneous nerves ; and a large branch, the cutaneus 'patella?, which pierces the sartorius and fascia lata at the inner side of the knee, and divides into many twigs, which are distributed to the integu- ment of the front of the knee. Above the patella this branch com- municates with the anterior branch of the internal cutaneous nerve, and with the terminal twigs of the middle, and external cutaneous. Below the patella it communicates with other branches of the long saphenous ; the whole of these communications constituting a kind of plexus (plexus patellae). The branches of the long saphenous nerve below the knee are distributed to the integument of the front and inner side of the leg. By one of these branches it communicates with the cutaneous branch of the obturator nerve. The muscular branches of the anterior crural nerve supply all the muscles of the front of the thigh (with the exception of the tensor vaginae femoris, which obtains its nerve from the superior gluteal) and the pectineus. The branch to the pectineus passes be- hind the sheath of the femoral vessels ; the branches to the sartorius, three or four in number, arise with the cutaneous nerves, and some- times are supplied by the latter. The branch to the rectus enters the deep surface of that muscle. The branch to the vastus externus follows the course of the descending branch of the external circum- flex artery ; the branch to the crureus passes directly to that muscle ; and the branch to the vastus internus, remarkable for its length, descends by the side of the sheath of the femoral vessels. The articular branches are distributed to the knee-joint; one enters the joint at its outer side, being derived from the nerve of the vastus externus ; the other, proceeding from the nerve of the vastus internus, descends with the anastomotica magna to a level with the joint, and then pierces the capsular ligament. The LUMBO-SACRAL NERVE.—The anterior division of the fifth 588 SACRAL NERVES. lumbar nerve, conjoined with a branch from the fourth, constitutes the lumbo-sacral nerve, which descends over the base of the sacrum into the pelvis, and assists in forming the sacral plexus. Immedi- ately before it joins the first sacral, it gives off the superior gluteal nerve, but this nerve is, notwithstanding, usually described as a branch of the sacral plexus. The connection of the nerves of the plexus with the anterior divisions of the lumbar nerves, may be most simply expressed in a tabular form, as follows :— Ilio-hypogastric . . . i. Ilio-inguinal i. Genito-crural . . . i, 2. External cutaneous . . . . 2, 3. Anterior crural . . . . 2, 3, 4. Obturator 3, 4. Lumbo-sacral 4, 5. SACRAL NERVES. There are five pairs of sacral nerves; the first four escape from the vertebral canal through the sacral foramina, the last between the sacrum and coccyx. The posterior sacral nerves are small, and diminish in size from above downwards; they communicate with each other by means of anastomosing loops immediately after their escape from the posterior sacral foramina, and divide like the other spinal nerves into external and internal branches. The external branches pierce the gluteus maximus, to which they give filaments, and are distributed to the integument of the posterior part of the gluteal region. The internal branches supply the multifidus spina; muscle and the integument over the sacrum and coccyx. The anterior sacral nerves diminish in size from above down- wards ; the first is large, and unites with the lumbo-sacral nerve ; the second, of equal size, unites with the first; and the third, scarcely one-fourth so large as the second, joins with the two preceding nerves in the formation of the sacral plexus. The fourth sacral nerve divides into two branches, one of which assists in forming the sacral plexus ; the other separates into three branches : a communicating branch, to unite with the fifth sacral nerve ; a visceral branch, to join with the hypogastric plexus and supply the bladder and prostate gland, and in the female the vagina ; and a muscular branch, which sends filaments to the levator ani and coccygeus, and a hccmorrhoidal branch to the sphincter ani and integument behind the anus. The fifth sacral nerve, issuing from between the sacrum and coccyx, pierces the coccygeus muscle, and receives the communi- cating branch from the fourth ; it then communicates with the coccygeal nerve, and piercing the coccygeus a second time, is distri- buted to the integument over the dorsal surface of the coccyx. SACRAL PLEXUS. 589 The coccygeal nerve pierces the coccygeus muscle, and unites with the fifth sacral nerve, in which it is lost. The connection between the fourth and fifth sacral nerves and the coccygeal is sometimes described as the coccygeal plexus. Fig. 341.—Side view of the nerves of the pelvis, me viscera having been removed. 1. Abdominal aorta. 2. Gangliated cord of sympathetic (left side). 3. Genito- crural nerve. 4. Left common iliac artery. 5. Right common iliac artery. 6. Left lumbo-sacral cord. 7. Psoas muscle. 8. Gangliated cord of sympathetic (right side). 9. Internal iliac artery (cut). 10. Gluteal artery (cut). 11. Right external iliac artery. 12. Right lumbo-sacral nerve. 13. Obturator nerve. 14. First sacral nerve. 15. Gluteal nerve. 16. Pyriformis of left side (cut). 17. Obturator artery. 18. Second sacral nerve. 19. Obturator internus. 20. Pyriformis of right side. 21. Nerve to levator ani. 22. Sacral plexus. 23. Levator ani (cut). 24. Third sacral nerve. 23. Bulb of urethra covered by accelerator urinse. 26. Nerve to ob- turator internus. 27. Transversus perinsei (cut). 28. Fourth sacral nerve. 29. Dorsal nerve of penis. 30. Visceral branches (cut). 31. Inferior pudendal nerve. 32. Fifth sacral nerve. 33. Small sciatic nerve. 34. Coccygeus muscle. 36. Sixth or coccygeal nerve. 38. Internal pudic nerve. 40. Inferior hsemorrhoidal nerve. 42. Posterior superficial perineal nerve. 44. Anterior superficial perineal nerve. 46. Deep perineal nerves to bulb and muscles. Each of the anterior divisions of the sacral nerves communicates with the sympathetic at its point of escape from the sacral canal. SACRAL PLEXUS.—The sacral plexus is formed by the union of the lumbo-sacral and the anterior divisions of the three upper sacral nerves and one-half the fourth. The plexus is triangular in form, its base corresponding with the whole length of the sacrum, and its apex with the lower part of the great sacro-ischiatic foramen. It is in relation behind with the pyriformis muscle, and in front with the pelvic fascia, which separates it from the internal iliac vessels and the viscera of the pelvis. The branches of the sacral plexus are— SACRAL NERVES. Visceral, Muscular, Superior gluteal, Inferior gluteal, Pudic, Lesser ischiatic, Greater ischiatic. The visceral nerves are three or four large branches derived from the fourth and fifth sacral nerves : they ascend by the side of the rectum and bladder; in the female by the side of the rectum, vagina, uterus, and bladder; and interlace with branches of the hypogastric plexus, sending in their course numerous filaments to the pelvic viscera. The muscular branches are one or two twigs to the levator anij an obturator branch, which curves around the spine of the ischium along with the pudic vessels and nerve, to reach the internal surface of the obturator interims muscle ; two twigs to the pyriformis; a branch to the gemellus superior; and a branch of moderate size, which descends between the gemelli muscles and the ischium, and is dis- tributed to the gemellus inferior, quadratus femoris, and capsule of the liip-joint. The SUPERIOR GLUTEAL NERVE arises from the lumbo-sacral near its junction with the first sacral nerve; it passes out of the pelvis with the gluteal artery, through the great sacro-iscliiatic fora- men above the pyriformis muscle, and divides into,a superior and an inferior branch. The superior branch follows the direction of the middle curved line of the ilium, accompanying the deep superior branch of the gluteal artery, and sends filaments to the gluteus medius and minimus. The inferior branch passes obliquely downwards and forwards between the gluteus medius and minimus, distributing numerous filaments to both, and terminates in the tensor vaginae femoris muscle. The superior gluteal nerve should, properly, be described with the lumbar plexus, as its fibres are entirely derived therefrom, the sacral plexus contributing nothing to its formation ; its description with the latter is, however, so thoroughly sanctioned by usage that we hesitate to make a change. The INFERIOR GLUTEAL NERVE is often described as a branch of the lesser iscliiatic, with which it is intimately connected. It arises from the lumbo-sacral cord and first and second sacral nerves, escapes from the pelvis through the greater sacro-sciatic foramen, PUDIC NERVE. below the pyriformis muscle, and enters the deep aspect of the gluteus maximus, to which it is distributed. The FUDIC NERVE arises from the lowest part of the sacral plexus and passes out of the pelvis through the great sacro-ischiatic foramen below the pyriformis muscle. It crosses the spine of the ischium, and re-entering the pelvis through the lesser sacro-ischiatic foramen, accompanies the internal pudic artery through Alcock’s canal, lying inferiorly to the artery and enclosed in the same sheath. Near its origin it gives off the inferior licemorrhoidal nerve, and in the outer wall of the ischio-rectal fossa divides into a superior and inferior branch. The inferior hsemorrhoidal nerve, often a branch of the sacral plexus, crosses the ischio-rectal fossa with the vessels of the same name, and descends to the termination of the rectum to be distributed to the sphincter ani and integument. The dorsalis penis nerve, the superior division of the internal pudic, ascends along the posterior surface of the ramus of the ischium, pierces the triangular ligament, and accompanies the arteria dorsalis penis to the glans, to which it is distributed. At the root of the penis the nerve gives off a cutaneous branch which runs along the side of the organ, gives filaments to the corpus cavernosum, and with its fellow of the opposite side supplies the integument of the upper two-thirds of the penis. The perineal nerve or inferior terminal branch, larger than the preceding, pursues the course of the superficial perineal artery in the perineum and divides into cutaneous and muscular branches. The cutaneous branches (superficial perineal), two in number, posterior and anterior, enter the ischio-rectal fossa and pass forward with the superficial perineal artery to be distributed to the integu- ment of the perineum, scrotum, and under part of the penis. The posterior superficial perineal nerve sends a few filaments to the in- tegument of the anus and sphincter ani; while the anterior gives off one or two twigs to the levator ani. The muscular branches proceed from a single trunk, which passes inwards behind the transversus perinei muscle; they are distributed to the transversus perinei, accelerator urinse, and erector penis. The perineal nerve also sends two or three filaments to the corpus spongiosum. In the female the pudic nerve is distributed to the parts analo- gous to those of the male. The superior branch supplies the clitoris ; the inferior the vulva and perineum. The LESSER ISCHIATIC NERVE arises from the second and third sacral nerves; it passes out of the pelvis through the great sacro- ischiatic foramen below the pyriformis muscle, and continues its course downwards through the thigh to the lower part of the popli- teal region, where it pierces the fascia and becomes subcutaneous. It then accompanies the external saphena vein to the lower part of the leg, and communicates with the external saphenous nerve. The branches of the lesser ischiatic nerve are all cutaneous ; they 592 are divisible into external, internal, and middle. The external cutaneous branches are several filaments which turn around the lower border of the gluteus maximus, and are distributed to the integu- ment over the hip and outer side of the thigh. The internal cutaneous branches are dis- tributed to the in- tegument of the upper and inner part of the thigh. One of these, larger than the rest, in- ferior pudendal, curves around the tuberosity of the ischium, pierces the fascia lata near the ramus of that bone, and, after communicating with one of the superficial peri- neal nerves, is dis- tributed to the in- tegument of the scrotum and penis. The middle cu- taneous branches, two or three in number, are de- rived from the lesser ischiatic in its course down the thigh, and are distributed to the integument. The GREAT ISCHIATIC NERVE is the largest nervous cord in the body ; it is formed by the sacral plexus, or rather is a pro- longation of the plexus, and at its exit from the great sacro-ischiatic foramen beneath the pyriformis muscle measures three-quarters of an inch in breadth. It descends through the middle of the space be- SACRAL NERVES. Fig. 342.—Dissec- tion of the but- tock and back of the thigh, i. Glu- teus maximus. 2. Gluteus medi- us. 3. Gluteal artery and nerve. 4. Gluteus mini- mus. 5. Nerve to obturator intern- us. 6. Pyriformis. 7. Pudic nerve. 8. Small sciatic nerve. 9. Great sacro-sciatic liga- ment. 10. Obtu- rator internus and gemelli. n. Inferior gluteal nerve. 12. Ten- don of obturator extern us. 13. Inferior puden- dal nerve. 14. Quadratus femo- ris. 15. Gracilis. 16. Great sciatic nerve. 17. Ad- ductor magnus. 18. Insertion of gluteus maxi- mus. 19. United origins of semi- tendinosus and biceps. 20. Short head of biceps. 21. Semi-mem- branosus. 22. Ten- don of biceps. 23. Tendon of semi- tendinosus. 24. External poplite- al nerve. 25. In- ternal popliteal nerve. 26. Com- municans pero- nei nerve. 27. Popliteal artery. 29. Gastrocne- mius. 31. Com- municans popli- tei nerve. INTERNAL POPLITEAL NERVE. 593 tween the trochanter major and tuberosity of the ischium, and along the posterior part of the thigh to its lower third, where it divides into two large terminal branches, internal and external popliteal. This division sometimes takes place at the plexus, and the two nerves descend side by side ; occasionally they are separated at their com- mencement by a part or by the whole of the pyriforinis muscle. The nerve in its course down the thigh rests on the gemellus superior, tendon of the obturator interims, gemellus inferior, quad- ratus femoris, and adductor magnus, and is covered by the gluteus maximus and biceps. The branches of the great ischiatic nerve, previously to its division, are, muscular and articular. The muscular branches are given off from the upper part of the nerve and supply both heads of the biceps, the semi-tendinosus, semi-membranosus, and adductor magnus. The articular branch descends to the upper part of the external condyle of the femur, and divides into filaments, which are dis- tributed to the fibrous capsule and synovial membrane of the knee- joint. The INTERNAL POPLITEAL NERVE passes through the middle of the popliteal space, from the division of the great ischiatic nerve to the lower border of the popliteus muscle, accompanies the artery beneath the arch of the soleus, and becomes the posterior tibial nerve. It is superficial in the whole of its course, and lies externally to the vein and artery. The branches of the internal popliteal nerve are — muscular or sural, articular, and a cutaneous branch, the external sa- phenous. The muscular branches, of considerable size, and four or five in number, are distributed to the two heads of the gastrocnemius, to the soleus, plantaris, and popliteus. The articular branches, two or three in number, supply the knee-joint, two of the twigs accompanying the internal articular arteries. The external or short saphenous nerve (communicans pop- litei, vel tibialis) proceeds from the middle of the internal popliteal, and descends in the groove between the two bellies of the gastroc- nemius muscle to the middle of the leg ; it then pierces the fascia, and, after receiving the communicans peronei, comes into relation with the external saphena vein, and follows the course of that vein to the outer ankle, to which, and to the integument of the heel and outer side of the foot (cutaneus dorsi pedis externus), it distributes branches. The POSTERIOR TIBIAL NERVE is continued along the pos- terior aspect of the leg from the lower border of the popliteus muscle to the posterior part of the inner ankle, where it divides into the internal and external plantar nerve. In the upper part of its course it lies to the inner side of the posterior tibial artery ; it then becomes placed superficially to that vessel, and at the ankle is situ- 594 PLANTAR NERVES. ated to its outer side ; in the lower third of the leg it lies parallel with the inner border of the tendo-Achillis. The branches of the posterior tibial nerve are — three or four muscular twigs to the deep muscles of the pos- terior aspect of the leg, the branch to the flexor longus hallucis accom- panies the nutrient artery of the fibula ; one or two filaments which entwine around the artery and then terminate in the integument; and a plantar cutaneous branch which pierces the internal annular ligament, and is distributed to the integument of the heel and inner border of the sole of the foot. The INTERNAL PLANTAR NERVE, larger than the external, crosses the posterior tibial vessels to enter the sole of the foot, and becomes placed be- tween the abductor hallucis and flexor brevis digitorum ; it then enters the sheath of the latter muscle, and divides opposite the base of the metatarsal bones into three digital branches ; one to supply the adjacent sides of the great and second toe ; the second, the adjacent sides of the second and third toe ; the third, the corresponding sides of the third and fourth toe. In its course the internal plantar nerve gives oft cutaneous branches to the integument of the inner side and sole of the foot; muscular branches to the muscles forming the inner and middle group of the sole ; a digital branch to the inner border of the great toe; and articular branches to the articulations of the tarsal and meta- tarsal bones. The EXTERNAL PLANTAR NERVE, the smaller of the two, follows the course of the external plantar artery to the outer border of the musculus Fig. 343.—Superficial nerves of the back of the leg. 1. Internal popliteal nerve. 2. External popliteal nerve. 3. Internal saphena vein. 4. Nervus communicans peronei. 5. Upper part of short saphenous nerve. 6. External saphena vein. 7. Internal saphenous nerve. 8. Lower part of short or external saphenous nerve. 9. Posterior tibial nerve. EXTERNAL POPLITEAL NERVE. 595 accessorius, beneath which it sends several deep branches to supply the adductor hallucis, interossei, transversus pedis, and the articulations of the tarsal and metatarsal bones. It then gives branches to the integument of the outer border and sole of the foot, and sends forward two digital branches to supply the little toe and half the next. Comparison of the Nerves of the Sole of the Foot with those of the Palm of the Hand.—The cutaneous distribution of the internal plantar nerve cor- responds to that of the median nerve, and that of the ex- ternal plantar to the ulnar. The flexor brevis digitorum is supplied by the internal plantar and probably cor- responds to the flexor sublimis in the hand, supplied by the correspond- ing nerve, the me- dian ; the abductor hallucis and two inner lumbricales of the foot are also supplied by the same nerve, and agree in all respects with those occupy- ing the same posi- tion in the hand. The flexor acces- sorius, adductor hallucis, two outer lumbricales, dorsal and palmar inter- ossei, transversus pedis, and muscles of the little toe are supplied by the external plantar nerve, a distribution corre- sponding very closely to that of the ulnar nerve in the hand. The flexor brevis hallucis differs from the flexor brevis pollicis in obtain- ing nerve supply for both heads from the same nerve, namely, the internal plantar. The EXTERNAL POPLITEAL NERVE (peroneal nerve), one-half smaller than the internal, passes downwards by the side of the tendon of the biceps, and crosses the outer head of the gastrocnemius Fig. 344.—Second stage of dissec- tion of sole of foot. x. Internal annular liga- ment. 2. Flexor brevis digitorum (cut). 3. Ex- ternal plantar nerve. 4. Ex- ternal plantar ar- tery. 5. Internal plantar nerve. 6. Abductor mini- mi digiti. 7. In- ternal plantar artery. 8. Acces- sorius muscle. 9. Abductor hallu- cis. 10. Flexor longus digito- rum. 11. Flexor longus hallucis. 12. Flexor brevis minimi digiti. 13. Digital branches of in- ternal plantar nerve. 14. Digi- tal branches of external plantar nerve. 15. Flexor brevis hallucis. 16. One of the lumbricales. 596 EXTERNAL POPLITEAL NERVE. and the head of the soleus, to the neck of the fibula ; it then pierces the peroneus longus muscle, and divides into two branches, anterior tibial and musculo-cutaneous. The branches of the external popliteal nerve are—communicans peronei, cutaneous, and articular. The communicans peronei, proceeding from the external pop- liteal near the head of the fibula, crosses the external origin of the gastrocnemius muscle, and, piercing the deep fascia, descends to the middle of the leg, where it joins the external saphenous nerve. It gives off one or two cutaneous filaments in its course. The cutaneous branch passes down the back part and outer side of the leg, supplying the integument. The articular branches follow the external articular arteries to the knee-joint. The ANTERIOR TIBIAL NERVE commences at the bifurcation of the external popliteal on the neck of the fibula, and passes beneath the upper part of the extensor longus digitorum, to reach the outer side of the anterior tibial artery, just as that vessel has emerged through the opening in the interosseous membrane. It descends the leg with the artery, lying at first to its outer side, then in front of it, and near the ankle becoming again placed to its outer side. Reach- ing the ankle it passes beneath the annular ligament, accompanies the dorsalis pedis artery, supplies the adjacent sides of the great and second toe, and communicates with the internal division of the mus- culo-cutaneous nerve. The branches given off by the anterior tibial nerve are—muscular to the muscles in its course ; and at the ankle a tarsal branch which may be considered as one of the terminal divisions of the nerve. This branch passes outwards upon the dorsum of the foot, becomes ganglionic like the posterior interosseous nerve at the wrist, and supplies the extensor brevis digitorum muscle and the articulations of the tarsus and metatarsus. The MUSCULO-CUTANEOUS NERVE passes downwards along the fibula, in the substance of the peroneus longus ; it then gets between the peroneus longus and brevis, next between the peronei and ex- tensor longus digitorum, and at the lower third of the leg pierces the deep fascia, and divides into the internal and external cutaneous nerves of the foot. In its course it gives off several branches to the peronei muscles and cutaneous branches to the skin of the lower part of the leg. The internal branch, the smaller of the two, is distributed to the inner side of the foot and great toe, and the adjoining sides of the second and third toes communicating with the anterior tibial and internal saphenous. The external, or larger branch, supplies the adjacent sides of the third and fourth, and fourth and fifth toes, and communicates with the external saphenous. SYMPATHETIC NERVES. 597 SYMPATHETIC NERVES. The sympathetic consists of a vertebral and prevertebral portion. The vertebral portion is composed of a series of ganglia united by a longitudinal cord ; it descends along each side of the vertebral column from the head to the coccyx, communicates with the cranial and spinal nerves, and distributes branches to the internal organs and viscera. The prevertebral portion is that part of the sympa- thetic which appertains to the viscera, comprising the numerous ganglia and plexuses of the head, chest, abdomen, and pelvis. The sympathetic nerve communicates with the cerebro-spinal nerves immediately at their exit from the cranium and vertebral canal. With the fourth and sixth nerve, however, it unites in the cavernous sinus; with the olfactory in the nose ; and with the auditory in the meatus auditorius interims. The branches of distribution accompany the arteries which supply the different organs, and form communications around them which are called plexuses, and take the name of the artery with which they are associated ; thus we have the mesenteric plexus, hepatic plexus, and splenic plexus. The chief ganglia in the head are four in number ; namely, the ophthalmic or lenticular, the spheno-palatine or Meckel’s, the otic or Arnold’s, and the submaxillary; three in the neck, superior, middle, and inferior cervical; twelve in the dorsal region ; four in the lumbar region ; and four or five in the sacral region. Each ganglion may be considered as a distinct centre, receiving and giving branches in four different directions, viz., superior or ascending, to communicate with the ganglion above ; inferior or descending, to communicate with the ganglion below ; external, to communicate with the spinal nerves ; and internal, to communicate with the sympathetic filaments of the opposite side, and be distributed to the viscera. As regards the spinal nerves it receives as well as gives, the white fibres of the sympathetic being derived from the cerebro- spinal nerves. CRANIAL PORTION OF THE SYMPATHETIC NERVE. Cranial Ganglia. Ophthalmic, or lenticular ganglion, Spheno-palatine, or Meckel’s ganglion, Otic, or Arnold’s ganglion, Submaxillary ganglion. The OPHTHALMIC GANGLION {ciliary; lenticular) is a small quadrangular and flattened ganglion situated within the orbit, between the optic nerve and external rectus muscle ; it is in close relation with the optic nerve and generally with the ophthalmic 598 SYMPATHETIC NERVES. artery ; and is surrounded by adipose tissue, which renders its dis- section somewhat difficult. It is of a reddish-grey colour, like other sympathetic ganglia. Its branches of distribution are the short ciliary nerves, which arise from its anterior angles in two groups ; the upper group con- sisting of about four filaments ; the lower, of five or six. They accompany the ciliary arteries in a waving course, and divide into filaments which pierce the sclerotic around the optic nerve to supply Fig. 345.—Cranial ganglia of the sympathetic nerve, x. Gan- glion of Ribes. 2. Filament by which it com- municates with the carotid plex- us (3). 4. Oph- thalmic or lenti- cular ganglion, giving off ciliary branches. 5. Part of the inferior division of the third nerve com- municating with the ganglion by means of a short thick branch (short root). 6. Part of the nasal nerve, connected with the gan- glion by means of a longer branch (long root). 7. A slender filament (the sympathetic root) from the carotid plexus. 8. Paid of the sixth nerve in the cavernous sinus, receiving two branches from the carotid plexus. 9. Meckel’s ganglion (spheno-palatine). 10. Spheno-palatine nerves. 11. Descending pala- tine branches. 12. Its internal or nasal branches. 13. Naso-palatine branch, one of the nasal branches. 14. Posterior branch of the ganglion, the Vidian nerve. 15. Its carotid branch, communicating with the carotid plexus. 16. Its petrosal branch, joining the intumeseentia gangliformis of the facial nerve. 17. Facial nerve. 18. Chorda tympani nerve, descending to join the lingual nerve. 19. Lingual nerve. 20. Submaxillary ganglion, receiving filaments from the chorda tympani and lingual. 21. Superior cervical ganglion of the sympathetic. * Naso- palatine ganglion of Cloquet. the tunics of the eyeball, the greater number of them being traceable to the iris and ciliary processes. Its branches of communication are three : one, the Iona root, proceeds from the nasal branch of the ophthalmic nerve and joins its superior angle ; a short and thick branch, the short root, from the inferior division of the third nerve to its inferior angle ; and a slender filament, the sympathetic root, from the cavernous plexus, which accompanies the long root to the ganglion. Occasionally the ophthalmic ganglion receives also a filament of communication from the spheno-palatine ganglion ; and sometimes from the abducens nerve. SPHENO-PALATINE GANGLION. 599 The SPHENO-PALATINE GANGLION (Meckel’s), the largest of the cranial ganglia of the sympathetic, is situated in the spheno-inaxillary fossa, a little below the superior maxillary nerve. It is of small size, of a reddish-grey colour, and triangular in shape ; and is placed on the posterior part of the spheno-palatine nerves which it only partially involves. Its branches are divisible into four groups : ascending, descending, internal, and posterior. The ascending branches are three or four small filaments which are distributed to the periosteum of the orbit. One of these branches sometimes joins the ophthalmic ganglion, one the sixth nerve, and two the optic nerve. The descending branches are the three palatine nerves—anterior, middle, and posterior. The anterior or large palatine nerve descends from the ganglion through the descending palatine canal, and emerges at the posterior palatine foramen. It then passes forward in a groove in the hard palate, to the mucous membrane of which it is distributed, and reaches the incisive foramen, where it communicates with the naso-palatine nerve. While in the descending palatine canal, this nerve gives off several branches (inferior nasal), which enter the nose through open- ings in the palate bone, and are distributed to the middle and inferior meatus, inferior spongy bone, and antrum. The middle or external palatine nerve descends externally to the preceding to the posterior palatine foramen, and distributes branches to the tonsil, soft palate, and uvula. The posterior or small palatine nerve quits the other nerves to enter a distinct canal, from which it emerges by a separate open- ing behind the posterior palatine foramen. It is distributed to the hard palate and gums near the point of its emergence, and also to the tonsil, soft palate, and uvula. The middle and posterior pala- tine nerves join with the branches of the glosso-pharyngeal in the formation of a plexus around the tonsil. The internal branches are the superior nasal and naso-palatine. The superior nasal nerves, four or five in number, enter the nasal fossa through the spheno-palatine foramen, and are distributed to the mucous membrane of the superior meatus, and superior and middle spongy bone. They are formed almost entirely by filaments derived from the superior maxillary nerve, which do not pass through Meckel’s ganglion. The naso-palatine nerve (Scarpa) enters the nasal fossa through the spheno-palatine foramen, and crosses the roof of the nares to reach the septum, to which it gives filaments. It then curves downwards and forwards along the vomer, to the naso-palatine canal, and passes through that canal to the palate, to which and to the papilla behind the incisor teeth it is distributed. The two nerves are contained in canals situated at the junction of the two superior maxillary bones, termed the canals of Scarpa; the right nerve is placed behind, the left in front. This nerve was described by Cloquet as uniting with its fellow in the naso-palatine canal and 600 SYMPATHETIC NERVES. constituting the naso-palatine ganglion. The existence of this gan- glion is disputed. The naso-palatine nerves are directly continuous with the spheno-palatine, derived from the superior maxillary, and are unconnected with the nerve cells of the ganglion. The posterior branches are the Vidian or pterygoid nerve, and the pterygo-palatine. The Vidian nerve, connected with the back part of the ganglion, passes directly backwards through the pterygoid or Vidian canal to the foramen lacerum basis cranii, where it divides into two branches, carotid and ■petrosal. The carotid branch crosses the foramen lacerum, surrounded by the cartilaginous substance which closes that opening, and enters the carotid canal to join the carotid plexus. The petrosal branch enters the cranium through the foramen lacerum basis cranii, piercing the cartilaginous substance, and passes backwards beneath the Gasserian ganglion and dura mater, embedded in a groove on the anterior surface of the petrous bone to the hiatus Fallopii. In the hiatus Fallopii it receives a branch from Jacob- son’s nerve, and terminates in the intumescentia gangliformis of the facial nerve. The Vidian nerve contains both the motor and sympathetic roots of Meckel’s ganglion, and most observers agree in regarding the motor power as derived from the facial nerve ; others, however, con- sider it to come from the spinal accessory or the glosso-pharyngeal. The pterygo-palatine nerve is a small branch which passes back- wards through the pterygo-palatine canal with the pterygo-palatine artery, to be distributed to the mucous membrane of the Eustachian tube and neighbouring part of the pharynx. Roots.—The spheno-palatine ganglion gets its motor root from the facial, spinal accessory, or glosso-pharyngeal, through the Vidian nerve, its sensory roots are the spheno-palatine branches of the supe- rior maxillary, and its sympathetic root is derived from the carotid plexus through the Vidian nerve. The OTIC GANGLION (Arnold’s) is a small oval-shaped and flattened ganglion, lying against the inner surface of the inferior maxillary nerve, close to the foramen ovale ; it is in relation, ex- ternally, with the trunk of that nerve, just at the point of union of the motor root; internally it rests against the cartilage of the Eustachian tube and tensor palati muscle; and posteriorly is in contact with the arteria meningea media. It is closely adherent to the internal pterygoid nerve, and appears like a swelling on that nerve. The branches of the otic ganglion are six in number ; two of dis- tribution and four of communication. The branches of distribution are—a small filament to the tensor tympani muscle, and one or two to the tensor palati. The branches of communication are—one or two filaments from the inferior maxillary nerve ; one or two filaments to the auriculo- temporal nerve, distributed with it to the parotid gland ; fila- ments from the nervi molles of the arteria meningea media, and the SUBMAXILLARY GANGLION. 601 lesser petrosal nerve. The latter nerve arises from the tympanic plexus in the middle ear, communicates with the gangliform en- largement on the facial nerve, traverses the petrous bone to emerge on its anterior surface through a minute opening external to the hiatus Fallopii; it crosses the middle fossa of the skull, and passes through the foramen ovale (or a special foramen) to join the otic ganglion. It conveys nerve filaments from the facial nerve and glosso-pharyngeal nerve, those from the former constituting the motor root, and those from the latter the sensory root of the gan- glion ; the sympathetic root coming from the nervi inolles on the middle meningeal artery. The SUBMAXILLARY GANGLION (Wharton’s) is a small round oi' triangular ganglion situated on the deep portion of the sub- Fig. 346.—Dissection show- ing inferior maxillary nerve and otic ganglion. 1. Sen- sory portion of fifth nerve, with Gasserian ganglion. 2. Tensor tympani. 3. Motor portion of fifth, passing be- neath ganglion. 4. Malleus. 5. Small superficial petrosal nerve. 6. Incus. 7. Otic ganglion. 8. Facial nerve. 9. Chorda tympani. 10. Meiubrana tympani. n. Tensor palati. 12. Middle meningeal artery. 13, 13. Lingual nerve. 14. Auri- culo-temporal nerve. 15. Inferior dental nerve. 16. External pterygoid. 17. Internal pterygoid. 18. In- ternal maxillary artery. 20, 20. Mylo-hyoid nerve. maxillary gland, in close relation with the lingual nerve, and near the posterior border of the mylo-hyoid muscle. Its branches of distribution, six or eight in number, divide into many filaments, which supply the side of the tongue, the sub- maxillary gland, sublingual gland, and Wharton’s duct. Its branches of communication are two or three from and to the lingual nerve ; one from the chorda tympani ; two or three which form a plexus with branches of the hypoglossal nerve ; and one or two filaments which pass to the facial artery, and commu- nicate with the nervi molles from the cervical portion of the sympathetic. Roots.—The motor root of the submaxillary ganglion is derived from the hypoglossal ; the sensory root from the lingual branch of the inferior maxillary, and the sympathetic root from the filaments which accompany the facial artery (nervi molles). CAROTID PLEXUS.—The ascending branch of the superior cervi- cal ganglion enters the carotid canal with the internal carotid artery, and divides into two branches, which form several loops of com- 602 SYMPATHETIC NERVES. munication with each other around the artery. These branches, together with those derived from the carotid branch of the Vidian, constitute the carotid plexus, situated for the most part on the outer side of the artery. The continuation of the carotid plexus onwards with the artery by the side of the sella turcica, is the cavernous plexus. The carotid plexus is the centre of communication between all the cranial ganglia and the sympathetic in the neck ; it also com- municates witli most of the cerebral nerves, and distributes filaments with each of the branches of the internal carotid, te accompany those branches to their ultimate ramifications. The branches which accom- pany the anterior cerebral artery at each side, unite upon the ante- rior communicating artery, and according to Ribes form a small ganglion, the ganglion of Ribes. The existence of this ganglion is disputed. The ophthalmic ganglion communicates with the plexus by means of the long branch which reaches it from the cavernous plexus, often in connection with the nasal nerve, but sometimes with the third. The spheno-palatine communicates with the plexus by means of the carotid branch of the Vidian. The otic ganglion is brought into connection with the plexus by means of the communication between the lesser petrosal nerve and tympanic plexus. The carotid plexus communicates with the third nerve in the cavernous sinus, and through the ophthalmic ganglion ; frequently with the fourth in the formation of the nerve of the tentorium ; with the Gasserian ganglion ; with the ophthalmic division of the fifth in the cavernous sinus, and by means of the ophthalmic gan- glion ; with the superior maxillary, through the spheno-palatine ganglion ; and with the inferior maxillary, through the otic ganglion. It sends two branches directly to the sixth nerve, which unite with it as it crosses the cavernous sinus ; it communicates with the facial and auditory nerves, through the medium of the petrosal branch of the Vidian ; and with the glosso-pharyngeal by means of two fila- ments to the tympanic nerve. CERVICAL PORTION OF THE SYMPATHETIC NERVE. The superior cervical ganglion is long and fusiform, of a reddish-grey colour, smooth, and of considerable thickness, extend- ing from within an inch of the carotid foramen in the petrous bone to opposite the lower border of the third cervical vertebra. It is in relation, in front, with the sheath of the internal carotid artery and internal jugular vein ; and, behind, with the rectus anticus major muscle. Its branches are divisible into superior, inferior, external, and internal; to which may be added, as proper to this ganglion, anterior. The superior (carotid nerve) is a single branch which ascends by the side of the internal carotid, and divides into two branches ; one lying to the outer, the other to the inner side of that vessel. The two branches enter the carotid canal, and, by their communications with each other and with the carotid branch of the Yidian, consti- tute the carotid plexus. The inferior or descending branch, sometimes two, is the cord of communication with the middle cervical ganglion. The external branches are numerous, and may be divided into two sets : those which communicate with the glosso-pharyngeal, pneumogastric, and hypoglossal nerve, and those which communi- cate with the first four cervical nerves. The internal branches are three in number: pharyngeal, to assist in forming the pharyngeal plexus ; laryngeal, to join the superior laryngeal nerve, and its branches; and superior cardiac nerve, or nervus superficialis cordis. The anterior branches accompany the external carotid artery with its branches, around which they form plexuses, and here and there small ganglia ; they are named, from the softness of their texture, nervi molles, and from their reddish hue, nervi subrufi. The branches accompanying the facial artery are conducted by that vessel to the submaxillary ganglion, and those which accompany the internal maxillary artery reach the otic ganglion through the medium of the middle meningeal artery. Small ganglia are found on these plexuses, and are named from the arteries on which they are situated. The largest of these is placed between the external and internal carotid arteries in the angle of bifurcation of the common carotid ; it is named the inter- carotid ganglion or gland, and has been described by Luschka as not truly ganglionic, but similar in structure to the coccygeal gland. The middle cervical ganglion (thyroid ganglion) is small, and sometimes wanting. It is situated opposite the fifth cervical vertebra, and rests against the inferior thyroid artery. Its superior branch, or branches, ascend to communicate with the superior cervical ganglion. Its inferior branches descend to join the inferior cervical gan- glion ; one of these frequently passes in front of the subclavian artery, the other behind it. Its external branches communicate with the fifth and sixth cervical nerves. Its internal branches are filaments which accompany the in- ferior thyroid artery, inferior thyroid plexus ; and the middle cardiac nerve, nervus cardiacus magnus. The inferior cervical ganglion (vertebral ganglion) is much larger than the preceding, and constant in its existence. It is of a semilunar form, and situated on the base of the transverse process of the seventh cervical vertebra, immediately behind the vertebral artery ; hence its designation, 11 vertebral ganglion Its superior branches communicate with the middle cervical ganglion. CERVICAL GANGLIA. 603 604 SYMPATHETIC NERVES. The inferior branches pass some before and some behind the subclavian artery, to join the first thoracic ganglion. The external branches consist of two sets; one which com- municates with the sixth, seventh, and eighth cervical, and first dorsal nerves, and one which accompanies the vertebral artery along the vertebral canal, forming the vertebral plexus. The plexus sends filaments to all the branches given off by that artery, and communicates in the cranium with the filaments of the carotid plexus accompanying the branches of the internal carotid artery. The internal branch is the inferior cardiac nerve, nervus cardiacus minor. CARDIAC NERVES.—The cardiac nerves are three in number at each side—namely, superior, middle, and inferior. The superior cardiac nerve (nervus superficialis cordis) proceeds from the lower part of the superior cervical ganglion ; it descends the neck behind the common carotid artery and parallel with the trachea, crosses the inferior thyroid artery, and running by the side of the recurrent laryngeal nerve, enters the chest. The nerve of the right side passes either in front of or behind the subclavian artery and along the posterior aspect of the arteria innominata to the deep cardiac plexus. The left superior cardiac nerve runs by the side of the left carotid artery, and crosses the arch of the aorta to the super- ficial cardiac plexus. In its course it receives branches from the pneumogastric nerve and its external laryngeal branch, and sends filaments to the thyroid gland and trachea. The middle cardiac nerve (nervus cardiacus magnus) proceeds from the middle cervical ganglion, or in its absence, from the cord of communication between the superior and inferior ganglion. It is the largest of the three nerves, and lies parallel with the recurrent laryngeal. At the root of the neck it divides into several branches, which pass some before and some behind the subclavian artery, communicates with the superior and inferior cardiac, pneumogastric, and recurrent nerves, and descends to the bifurcation of the trachea, to join the deep cardiac plexus. On the left side this nerve passes between the left carotid and subclavian arteries to reach the chest, and terminates in the left side of the deep cardiac plexus. The inferior cardiac nerve (nervus cardiacus minor) arises from the inferior cervical ganglion, communicates with the recurrent laryngeal and middle cardiac nerves, passes behind the subclavian artery and descends to the front of the bifurcation of the trachea, to the deep cardiac plexus. The nerve of the left side often unites with the middle cardiac nerve, either before or immediately after they enter the thorax, the combined cord joining the deep cardiac plexus. The SUPERFICIAL CARDIAC PLEXUS is situated immediately beneath the arch of the aorta and in front of the right pulmonary artery. It receives the superior cardiac nerve of the left side and the inferior cardiac branch of the left pneumogastric nerve, both CAKDIAC PLEXUSES. 605 of which cross the arch of the aorta between the left phrenic and pneumogastric nerve. It receives besides several filaments from the Fig. 347.—Scheme of the formation of the deep and superficial cardiac plexuses. 1. Superior cervical ganglion of the sympathetic. 2. Middle ganglion. 3. Inferior ganglion. 4. Superior cervical sympathetic cardiac branch. 5. Middle cardiac. 6. Inferior cardiac. 7. First dorsal sympathetic ganglion. 8. Second dorsal gan- glion. 9. Vagus. 10. Recurrent laryngeal, n. Superior cervical cardiac branch of vagus. 12. Inferior cardiac branch of vagus. 13. Thoracic cardiac branches of vagus. 14. Cardiac branches of left recurrent nerve. 15. Superficial cardiac plexus and ganglion. 16. Communicating branches between deep and superficial plexus. 17. Deep cardiac plexus. 18. Right and, 19. Left coronary plexuses. deep cardiac plexus, and sometimes a cardiac branch from the right pneumogastric nerve. Connected with the plexus is a small ganglion 606 SYMPATHETIC NERVES. (sometimes wanting), the cardiac ganglion of Wrisberg, which lies close to the right side of the fibrous cord of the ductus arteri- osus. The superficial cardiac plexus gives off filaments which pass along the front of the left pulmonary artery to the root of the left lung, where they communicate with the anterior pulmonary plexus ; while the principal part of the plexus descends in the groove between the pulmonary artery and aorta to the anterior longitudinal sulcus of the heart, where it comes into relation with the anterior coronary artery, and becomes the anterior coronary plexus. At the base of the heart, the anterior coronary plexus receives several filaments from the deep cardiac plexus. Its branches are distributed to the substance of the heart in the course of the left or anterior coronary artery. The DEEP or GREAT CARDIAC PLEXUS is situated on the bifur- cation of the trachea, above the right pulmonary artery and behind the transverse portion of the arch of the aorta. It receives on the right side the three cardiac nerves of the sympathetic of the same side, and the cardiac branches of the right pneumogastric and right recurrent nerve. On the left side it receives the middle and in- ferior cardiac nerves of the sympathetic of the left side ; the cardiac branches of the left pneumogastric (excepting the inferior), and several cardiac branches from the left recurrent nerve. Filaments also pass to this plexus from the first and second thoracic ganglia of both sides. It will be noted that the deep cardiac plexus receives all the cardiac filaments of the sympathetic, pneumogastric, and recurrent nerves, with the exception of the left superior cardiac of the sym- pathetic (nervus superficialis cordis) and the inferior cervical cardiac of the left pneumogastric, these two nerves being destined to the superficial cardiac plexus. The branches of the deep cardiac plexus, proceeding from its right and left division, pass downwards to join the coronary arteries, and outwards to the pulmonary plexuses. From the right division of the plexus the branches proceed before and behind the right pulmonary artery. Those which pass in front descend upon the trunk of the pulmonary artery to the left coronary artery, and help to form the anterior coronary plexus; those which pass behind the right pulmonary artery are distributed to the right auricle ; a third set of filaments, proceeding from the right division of the deep cardiac plexus, follow the course of the right pulmonary artery to the anterior pulmonary plexus. From the left division of the plexus branches proceed beneath the arch of the aorta immediately to the right of the ligament of the ductus arteriosus to join the superficial cardiac plexus ; others pass outwards with the pulmonary artery to the pulmonary plexus ; a few descend to the left auricle ; but the chief bulk pass on to the right coronary artery and form the posterior coronary plexus. The anterior coronary plexus proceeds from the superficial cardiac plexus, and receives other filaments from the deep cardiac plexus. It is distributed with the branches of the coronary artery on the anterior aspect of the heart. The posterior coronary plexus proceeds from the deep cardiac plexus, and principally from its left division. It follows the course of the arteries distributed to the posterior aspect of the heart. THORACIC GANGLIA. 607 THORACIC PORTION OF THE SYMPATHETIC NERVE. The thoracic portion of the sympathetic nerve is the trunk of the sympathetic in its course through the cavity of the thorax. It lies by the side of the vertebral column on the heads of the ribs and inter- costal spaces, but at its lowest part comes into relation with the sides of the bodies of the two last dorsal vertebrae. The THORACIC GANGLIA (Fig. 348) are twelve in number at each side. They are flattened and tri- angular, or irregular in form, and present the peculiar reddish-grey colour and pearly lustre of sym- pathetic ganglia in general; they rest against the heads of the ribs, and are covered by the pleura cos- talis. The first two ganglia and the last are usually the largest; the latter being situated on the side of the body of the last dorsal vertebra. Their branches are branches of communication and branches of distribution. Some ascending fila- ments from the first ganglion assist in the formation of the vertebral plexus. The external or communicating branches, usually two in number for each ganglion, communicate with the intercostal nerves ; of these, one is greyish in colour, and is believed to pass from the gan- glion to the spinal nerve ; the other, of a white colour, probably is spinal in its origin, and is distributed with the sympathetic nerves. The internal or visceral branches proceeding from the five or six upper ganglia, are of small size, and distributed to the aorta, heart, oesophagus, vertebral column, and lungs. The branches to Fig. 348.—Diagram of the thoracic sympathetic chain, and the branches given off from it. Opposite 3, the communications with one of the d rsal nerves are shown SYMPATHETIC NERVES. 608 the lungs proceed from the third and fourth ganglia, and go to join the posterior pulmonary plexus. The visceral blanches of the six lower ganglia unite to form the three splanchnic nerves. The great splanchnic nerve proceeds from the sixth dorsal gan- glion, and receiving the branches of the seventh, eighth, ninth, and tenth, passes downwards along the front of the vertebral column, and, piercing the crus of the diaphragm, terminates in the semi- lunar ganglion. The lesser splanchnic nerve is formed by filaments which issue from the tenth and eleventh ganglia ; it pierces the crus of the dia- phragm, and joins the solar plexus near the middle line, frequently distributing branches also to the renal plexus. The third or renal splanchnic nerve proceeds from the last thoracic ganglion, and, piercing the diaphragm, terminates in the renal plexus. When absent, the place of this nerve is supplied by the lesser splanchnic. The semilunar ganglion is a large, irregular, gangliform body, pierced by numerous openings, and appearing like the aggregation of a number of smaller ganglia, having spaces between them. By its upper and posterior extremity each ganglion receives the corre- sponding great splanchnic nerve. It is situated by the side of the coeliac axis and root of the superior mesenteric artery, and extends outwards to the supra-renal capsule. The ganglia" communicate both above and below the coeliac axis and form a gangliform circle, from which branches pass off in all directions, like rays from a centre. Hence the entire circle has been named the solar plexus. The solar or epigastric plexus receives the great and lesser splanchnic nerves, the termination of the right pneumogastric nerve, some filaments from the right phrenic nerve, and sometimes one or two from the left. It sends forth numerous filaments which accompany, under the name of plexuses, all the branches given off by the abdominal aorta. Thus we have derived from the solar plexus the— Phrenic, or diaphragmatic plexuses, Gastric plexus, Hepatic plexus, Splenic plexus, Supra-renal plexuses, Renal plexuses, Superior mesenteric plexus, Aortic plexus, Spermatic plexuses,' Inferior mesenteric plexus. In connection with the phrenic plexus of the right side, there is described a small ganglion diaphragmaticum, which is situated near the supra-renal capsule. In this ganglion branches of the right phrenic nerve communicate with those of the sympathetic. The supra-renal plexuses are remarkable for their large size, and for a ganglion, which has received the name of ganglion supra- renale. The renal plexuses are large, and receive the third splanchnic nerve, They are joined by filaments from the aortic plexus and lesser splanchnic nerve. The nerves passing to the kidney from each plexus are about fifteen or twenty in number ; they accompany the branches of the renal artery and have numerous small ganglia upon them. Branches are given off from the renal plexuses to the inferior vena cava and spermatic plexuses. The superior mesenteric plexus has several small ganglia at the root of the artery; and its nerves, which are whiter than those of the other plexuses, form a kind of nervous sheath to the artery and its branches. The aortic plexus is a continuation of the solar plexus down- wards on the aorta, for the supply of the inferior branches of that trunk ; it receives also branches from the renal plexuses and lumbar ganglia. It is the source of origin of the inferior mesenteric plexus and part of the spermatic plexus, and terminates below in the hypogastric plexus. It likewise distributes branches on the infe- rior vena cava. The spermatic plexus is derived from the renal plexus, but receives filaments from the aortic plexus. The inferior mesenteric plexus is derived chiefly from the aortic plexus. LUMBAR GANGLIA. 609 LUMBAR PORTION OF THE SYMPATHETIC NERVE. The lumbar portion of the trunk of the sympathetic is situated on the vertebral column, close to the anterior border of the psoas magnus muscle. It is continuous above, under the edge of the diaphragm, with the thoracic portion of the nerve, and below it descends upon the sacrum, in front of the anterior sacral foramina, to the coccyx. It presents four small ganglia and an intermediate cord. The lumbar ganglia, four in number at eacli side, of a pearly- grey colour and fusiform shape, are situated on the anterior part of the bodies of the lumbar vertebra). The branches of the lumbar ganglia are branches of communi- cation and branches of distribution. The external or communicating branches, two or three in number from each ganglion, and longer than in the other regions, communicate with the lumbar nerves. The internal or visceral branches consist of two sets: the upper pass inwards in front of the abdominal aorta, and join the aortic plexus ; the lower cross the common iliac arteries, and rinite over the promontory of the sacrum to form the hypogastric plexus. The hypogastric plexus is formed by the termination of the aortic plexus, and by the union of branches from the lower lumbar ganglia. It is situated over the promontory of the sacrum, between the two common iliac arteries, and bifurcates interiorly into two lateral portious, inferior hypogastric or pelvic plexuses. 610 SYMPATHETIC NERVES. PELVIC PLEXUSES. The inferior hypogastric or pelvic plexus on each side is placed in the lower part of the pelvic cavity, at the side of the rectum and bladder, extending in the female to the side of the vagina also. The nerve filaments are derived from the hypogastric plexus ; they form frequent communications, and small ganglia are situated at the points of intersection ; additional filaments are derived from the second, third, and fourth sacral nerves, and from the two upper sacral sym- pathetic ganglia. The plexus gives off branches to all the pelvic viscera, which follow the distribution of the internal iliac artery, and receive the same names as the branches of that vessel which they accompany. The nerves distributed to the bladder and vagina contain more nerve filaments derived from spinal nerves than the other branches of the plexus. The hsemorrhoidal plexus arises from the back of the pelvic plexus, and passes to the rectum, where it communicates with the superior haemorrhoidal branches of the inferior mesenteric plexus. The vesical plexus comes from the front of the pelvic plexus. The nerves at first accompany the vesical arteries, but afterwards leave them, and penetrate the muscular coat to reach the mucous membrane. They are chiefly distributed to the base and sides of the bladder, and form secondary plexuses on the vasa deferentia and vesiculoe seminales. The prostatic plexus is given off by the lower part of the pelvic plexus. It consists of nerves of considerable size, which are dis- tributed to the prostate gland, vesicula) seminales, and penis ; those passing to the latter organ are named cavernous nerves, being dis- tributed to the corpus cavernosum. The vaginal plexus, derived from the lower part of the pelvic plexus, is distributed to the mucous membrane and erectile tissue of the vagina. The uterine plexus, given off by the upper part of the pelvic plexus, accompanies the branches of the uterine artery, between the layers of the broad ligament, to the side of the uterus. The nerves are for the most part distributed to the mucous membrane of the lower part of the body and cervix, several large ganglia being found in the plexus by the side of the cervix ; other branches pass to the muscular coat, penetrating as far as the fundus. SACRAL PORTION OF THE SYMPATHETIC NERVE. The sacral ganglia are four or five in number at each side. They are situated on the sacrum, close to the anterior sacral foramina, and resemble the lumbar ganglia in form and mode of connection, although much smaller in size. The external or communicating branches are two from each ganglion, which pass outwards to communicate with the anterior sacral nerves and with the coccygeal nerve. ORGANS OF SENSE. 611 The internal or visceral branches communicate very freely with the inferior hypogastric plexuses, and are distributed to the pelvic viscera. The last pair of sacral ganglia give off branches which join a small ganglion, situated on the first bone of the coccyx, called the ganglion impar, or azygos. This ganglion serves to connect the extremities of the two sympathetic nerves. It gives off a few small branches to the coccyx and rectum, and communicates with the coccygeal nerve. Numerous branches from the ganglion impar are given off to a peculiar reddish body situated on the anterior aspect of the tip of the coccyx, and called by Lusclika, by,whom it was first described, the coccygeal glands It consists of an aggregation of little lobules or granules, and has been shown by Arnold to be formed by a number of dilated and tortuous arteries connected with the middle sacral artery. In the stroma of the organ scattered nerve cells are found. COCCYGEAL GLAND. ORGANS OF SENSE. Tlie organs of sense, the instruments by which the animal frame is brought into relation with surrounding nature, are five in number. Four of these organs are situated within the head ; viz., the appa- ratus of smell, sight, hearing, and taste ; the remaining organ, that of touch, is resident in the skin, and distributed over the surface of the body. The latter was described in the section on Histology, p. 63. THE NOSE AND NASAL FOSSAE The organ of smell consists essentially of two parts : one external, the nose ; the other internal, the nasal fossae. The nose is the triangnlar pyramid which projects from the centre of the face, immediately above the upper lip. Superiorly it is con- nected with the forehead hy means of a narrow bridge ; inferiorly, it presents two openings, the nostrils, which overhang the mouth, and are so constructed that the odour of all substances must be re- ceived by the nose before they can be introduced within the lips. The septum between the openings of the nostrils is called the columna. Their entrance is guarded by a number of stiff hairs (vibrissce) which project across the openings, and act as a filter in preventing the introduction of foreign substances, such as dust or insects, with the current of air intended for respiration. The anatomical elements of which the nose is composed are : i. Integument. 2. Muscles. 3. Bones. 4. Cartilages. 5. Mucous membrane. 6. Vessels and nerves. 1. The integument forming the tip (lobulus) and wings {alee) of the nose is extremely thick and dense, so as to be with difficulty separated from the cartilages. It is furnished with an abun- 612 ORGANS OF SENSE. dance of sebaceous glands, which, by their oily secretion, protect the extremity of the nose under alternations of temperature. The seba- ceous matter of these glands becomes of a dark colour near the surface, from altered secretion, and also from attraction of the car- bonaceous matter floating in the atmosphere ; hence the spotted appearance which the tip of the nose presents in large cities. When the integument is firmly compressed, the inspissated sebaceous secretion is squeezed out, and taking the cylindrical form of the excretory ducts of the glands, has the appearance of small white maggots (grubs ; comedones) with black heads. 2. The muscles are brought into view by reflecting the integu- ment ; they are the pyramidalis nasi, compressor nasi, dilatator naris, levator labii superioris alseque nasi, and depressor ahe nasi. They have been already described with the muscles of the face. 3. The bones of the nose are—the nasal, and nasal processes of the superior maxillary. 4. The cartilages give form and stability to the nose, providing, at the same time, by their elasticity, against injuries. They are five in number, namely, the— Cartilage of the septum, Two lateral cartilages, Two alar cartilages. The cartilage of the sep turn, somewhat triangular in form, divides the nose into its two nostrils. It is connected above with the nasal bones and lateral cartilages ; be- hind, with the ethmoidal sep- tum and vomer; and below, with the palate processes of the superior maxillary bones. The alar cartilages and co- lumna move freely on the cartilage of the septum, being but loosely connected with it by perichondrium. The lateral cartilages are also triangular ; they are connected, in front, with the cartilage of the septum ; above ', with the nasal bones ; behind., with the nasal processes of the superior maxillary bones ; and below, with the alar cartilages. Alar Cartilages (lower lateral cartilages).—Each of these cartilages is curved so as to correspond with the walls of the nostril, to which it forms a kind of rim. The inner portion is loosely con- nected with the same part of the opposite cartilage, to form the columna. It is expanded and thickened at the point of the nose, to constitute the lobe; and on the side makes a curve corresponding with that of the ala. This curve is prolonged backwards and down- wards in the direction of the posterior border of the ala by three or Fto. 349. — The cartilages of the nose. 1. One of the nasal bones. 2. Cartilage of the septum. 3. La- teral cartilage. 4. Alar carti- lage. 5. Cen- tral portions of the alar carti- lages which constitute the columna. 6. Sesamoid car- tilages. 7. Tlie nostril. NASAL FOSSA:. 613 four small cartilaginous plates (sesamoid cartilages), which are appendages of the alar cartilage. The whole of the cartilages are connected with each other, and to the bones, by perichon- drium, which, from its membranous structure, permits of the freedom of motion existing be- tween them. The lower margin and back part of the ala of the nose is devoid of cartilage, and is com- posed of areolar and elastic tissue to which the skin is closely ad- herent ; it resembles the lobule of the ear. 5. The mucous mem- brane, lining the inte- rior of the nose, is con- tinuous with the skin externally, and with the pituitary membrane of the nasal fossse within. Around the en- trance of the nostrils it is provided with the vibrissce. 6. Vessels and Nerves.—The arteries of the nose are—the lateral nasal from the facial, the artery of the septum from the superior coronary, the nasal branch of the ophthalmic and the infra-orbital. Its nerves are—the facial, infra-orbital, infra-trochlear, and nasal branch of the ophthalmic. Fig. 350. — The cartilages and bones of the nose viewed from the side. 1. Nasal bone. 2. Nasal pro- cess of the superior max. illary bone. 3. Cartilage of the septum. 4. Lateral car- tilage. 5, 5. Alar carti- lage. 6. Inner portion of the alar cartilage. 7. Sesamoid cartilages. 8. Areolar tis- sue of the ala nasi. 9. Aper- ture of the nostril. NASAL FOSS.E. To obtain a good view of the nasal fossae, the face must be divided through the nose by a vertical incision, a little to one side of the middle line. The nasal fossae are two irregular, compressed cavities, extending backwards from the nose to the pharynx. They are bounded supe- riorly by the lateral cartilages of the nose, and by the nasal bones, ethmoid, and sphenoid ; interiorly by the hard palate ; and, in the middle line, they are separated by a bony and cartilaginous septum. A plan of the boundaries of the nasal fossae will be found at p. 129. On the outer wall of each fossa, in the dried skull, are three pro- jecting processes, termed spongy bones. The two superior belong to the ethmoid, the inferior is a separate bone. In the fresh fossae these are covered with mucous membrane, and serve to increase the surface of that membrane by their prominence and convoluted form. The space intervening between the superior and middle spongy bone is the superior meatus ; the space between the middle and inferior, 614 ORGANS OF SENSE. the middle meatus ; and that between the inferior and the floor of the fossa, the inferior meatus. The openings into these spaces have been described along with the bones of the skull, p. 129. It should, however, be noted that two of the openings there mentioned, namely, the spheno-palatine and anterior palatine foramina, are not seen in the recent state, being covered by the mucous membrane. In the position of the anterior palatine canal there is, not unfrequently, a small caecal tube, the remains of a structure present in the man during embryonic life, and called the organ of Jacobson. This organ is present in mammals generally in adult life, and appears as a double tube in the nasal septum, supported by a plate of cartilage, the cartilage of Jacobson. The mucous membrane of the nasal fossae is called 'pituitary, or Schneiderian; the former name being derived from the nature of its secretion, the latter from Schneider, who was the first to show that the secretion of the nose proceeded from the mucous membrane, and not from the brain, as was previously imagined. It is closely adherent to the periosteum, constituting what is called a fibro- mucous membrane, and is continuous with the general gastro - pulmonary mucous membrane. From the nasal fossae it may be traced through the openings in the meatuses, into the sphenoidal and ethmoidal cells ; into the frontal sinuses ; into the antrum maxillare ; through the nasal duct to the surface of the eye, where it is con- tinuous with the conjunctiva; along the Eustachian tubes into the tym- panum and mastoid cells, to which it forms the lining membrane ; and through the posterior nares into the pharynx and month, and thence through the lungs and alimen- tary canal. Bigelow has pointed out that the mucous membrane covering the middle and inferior turbinated bones contains a true cavernous structure, similar to that of the corpus cavernosum penis. The cavernous spaces are irregular in shape and variable in size they approach quite near to the surface of the mucous membram and the bone, and they communicate freely with each other. The surface of the membrane is furnished with laminated squa- mous epithelium near the aperture of the nares, and with ciliatec columnar epithelium in the respiratory tract; in the latter it is alsc furnished with mucous glands, which are especially numerous 01 the septum at its posterior part. The mucous membrane whicl covers the upper and middle turbinated bones and the upper par' of the septum (the olfactory tract) is of a darker colour, softer anc more pulpy, its epithelium is columnar and non-ciliated, and the Fia. 351.—A section of the mucous membrane in the olfactory re- gion. 1. Coloured part of the epithelium. 2. Nucleus. 3. Deeper part, containing olfactory cells and filaments. 4. Connec- tive tissue. 5, 5. Mucous glands. 6, 6. Nerve twigs giving off ter- minal branches. ORGAN OF VISION. 615 epithelial processes are prolonged at their deep extremities into threads which appear to join the connective tissue corpuscles. It also contains numerous glands, but these are more simple than the glands of the respiratory tract. Mingled with the cells of the columnar epithelium are cer- tain peculiar rod-like bodies, each of which is connected with or grows out from a nucleated cell (olfactory cell), while from the deeper surface of the same cell proceeds a fine thread, which is supposed to be continuous with a filament of the olfactory nerve. They bear a striking resemblance to the retinal rods and cones. Vessels and Nerves. — The arteries of the nasal fossa; are the anterior and posterior ethmoidal, from the ophthalmic; and spheno- palatine and pterygo-palatine from the internal maxillary. The nerves are — olfactory, spheno-palatine and naso-palatine from Meckel’s ganglion, and nasal branch of the ophthalmic. The filaments of the olfactory nerves differ from those of the cere- bral and spinal nerves generally, in being devoid of the medullary sheath ; they form a fine anastomotic network, and probably ter- minate in the olfactory cells above described. In the frog the olfac- tory fibres have been observed breaking up into a bundle of fine, pale, varicose fibrils which perforate the mucous membrane, and each of these appeal's then to join an olfactory cell (Schultze and Kolliker). Pig. 352.—Olfactory cells and nerve ter- minations. A. Olfactory cells from frog. b. From man. c. Filaments of olfactory nerve from dog. 1. Epithelial cells, extending deeply into ramified processes. 2. Olfactory cells. 3. The rod-like processes of olfactory ceils. 4. Their ciliated extremities. 5. Their central filaments. ORGAN OF VISION. The organ of vision consists of the two eyes and their connections with the brain. The eyes are situated in the orbital fossae, on each side of the upper part of the face ; they are freely movable in consequence of being surrounded by fat and contained in a smooth fibrous capsule (capsule of Tenon), and have numerous muscles to perform their movements. They are protected from external violence by being situated in cavities with osseous walls, and have in front both 616 ORGANS OF SENSE. cleansing and protective apparatus against the intrusion of foreign bodies. The fossae in which the eyes are situated have their axes directed outwards, but the eyes themselves are directed much more forwards, varying, however, in their direction with the distance or nearness of the object looked at, their axes being parallel in looking at distant objects, but converging slightly when near objects are viewed. The optic nerves follow the direction of the orbits, and therefore enter the eyeballs on their nasal side. We shall in the first place give a short account of those structures which, although not essential to vision, are provided for the protec- tion of the anterior part of the eye. These appendages of the eye (tutamina oculi) are—the eyebrows, eyelids, eyelashes, conjunctiva, caruncula lachrymalis, and lachrymal apparatus. The eyebrows (supercilia) are two prominent arches of integu- ment which overlie the superciliary ridges of the frontal bone. APPENDAGES OF THE EYE. Pig. 353.—Appendages of the eye. 1. Supe- rior tarsal plate. 2. Lower border of the plate on which are seen the open- ings of the Meibomian glands. 3. In- ferior tarsal plate ; along the upper border of this plate the openings of the Meibomian glands are likewise seen. 4. Lachrymal gland, its superior or or- bital portion. 5. Inferior or palpebral portion. 6. Lachrymal ducts. 7. Plica semilunaris. 8. Caruncula lachrymalis. p. Puncta lachrymalia. 10. Superior lachrymal canaliculus. 11. Inferior lach- rymal canaliculus. 12. Lachrymal sac. 14. Dilatation of the nasal duct, where it opens into the inferior meatus of the nose. 15. Nasal duct. They are covered with short, stiff hairs directed obliquely upwards and outwards, and are connected beneath with the orbicularis pal- pebrarum, occipito-frontalis, and corrugator supercilii muscles, by which they are moved. They serve to shade the eyes from too vivid light, to protect them from the entrance of dust from above, and to carry the moisture from the forehead on to the temple and lateral part's of the face, and so prevent its entering the eyes. The eyelids (palpebrce) are two movable folds, which serve by their closure to protect the anterior part of the eye from injury, or to exclude the light, as during sleep. When open they have an elliptical fissure between them (rima palpebrarum), and it is upon the size of this that the apparent size of the eye depends. The angles of junction of the two lids are called canthi. The outer canthus is acute, so that but a small space is left between the lids ; the inner canthus is prolonged for a short distance towards the nose, and a triangular space called lacus lachrymalis is left between EYELIDS. 617 the lids in this situation. At the commencement of this space, upon the edge of each of the lids, is a small angular projection, the lachrymal papilla ; and at the apex of each papilla is a small orifice, punctum lachrymale, the commencement of the lachrymal canaliculus. The eyelids have entering into their structure, integument, orbi- cularis palpebrarum muscle, tarsal plates, palpebral ligament, Mei- bomian glands, and conjunctiva. The areolar tissue of the skin of the eyelids is remarkable for its looseness, and the absence of adipose substance; it is particularly liable to serous infiltration. The fibres of the orbicularis are for the most part thin and pale, but a thicker band of fibres has been found internal to the eye- lashes, constituting the ciliary muscle of Riolan. The tarsal plates are two thin plates of dense connective tissue, about an inch in length, which give form and support to the eyelids. The upper plate, is of a semilunar form, thicker in the middle than at its extremities ; its lower border is broad and flat, its upper thin, and gives attachment to the levator palpebrse muscle and the palpebral ligament. The lower plate, narrower than the upper, is situated in the substance of the lower lid. Its upper border is flat, and corresponds with the flat edge of the upper plate ; the lower border is attached to the palpebral ligament. Near the inner canthus, the tarsal plates terminate at the commencement of the lacus lachrymalis, and are attached to the margin of the orbit by the tendo oculi. At their outer extremity they terminate at a short distance from the canthus, and are retained in position by a fibrous band which is part of the palpebral ligament, and is called the external tarsal ligament. The palpebral ligament (broad tarsal ligament) is a fibrous mem- brane which is firmly attached to the periosteum around the margin of the orbit, and to the internal free edges of the tarsal plates. It is thick and dense for the outer half of the orbit, but becomes thin to its inner side. Its use is to retain the tarsal plates in their place, and give support to the lids. The Meibo- mian glands are embedded in grooves on the under sur- face of each tar- sal plate, and are distincthfseen on examining the inner aspect of the lids. They have the appearance of parallel strings of pearls, about thirty in Fig. 354.—Meibomian glands, as seen upon the inner side of the eyelids. 1. Upper lid. 2. Lower lid. 3, 3. Conjunctiva. 4. Apertuies of the Meibomian glands, forming a row along the free border of each eyelid. 5, 5. Papillae lachry- males. 6, 6. Puncta lachrymalia. 7. Apertures of the efferent ducts of the lachrymal gland. 618 ORGANS OF SENSE. number in the upper plate, and somewhat fewer in the lower ; they open by minute foramina on the edges of the lids. They correspond in length with the breadth of the plate, and are consequently longer in the upper than in the lower lid. Each gland consists of a single lengthened follicle or tube, into which a number of small clusters of glan- dular vesicles open ; the latter are so numerous as almost to conceal the tube by which the secretion is poured out on the edges of the lids. Occasionally an arch is formed between two of the follicles, pro- ducing a graceful ap- pearance. The tubes are lined by a stratified epithelium, and the gland vesicles by cubi- cal cells ; the lumen of the gland is usually filled up with the fatty secretion and partly disintegrated epithe- lial cells. The edges of the eyelids are furnished with strong, short, curved hairs, called eyelashes (cilia), ar- ranged in two to four rows ; those of the upper lid curving up- wards, and those of the lower downwards, so as not to interlace with each other in the closure of the lids, and prove an impedi- ment to the opening of the eyes. Near the point of emergence of the eyelashes are the openings of the glands of Moll, arranged in Fro. 355.—Vertical antero-posterior section of upper eyelid. a. Skin. b. Orbicularis palpebrarum. Ciliary muscle of Riolan, c. Levator palpebrse. d. Conjunctiva, c. Meibomian gland, with (/) its duct. g. Gland of Moll. h. Eyelashes, i, i. Hair follicles containing hairs, j, j. Sweat glands. k. Racemose glands of conjunctiva. CONJUNCTIVA. 619 several rows; the glands themselves are situated near the roots of the hairs, and between the fibres of the mass of the orbicularis and the ciliary muscle of Eiolan. In structure they resemble sweat ducts, being composed of a bent tube, lined with cubical epithelial cells. The conjunctiva is the mucous membrane of the eye. It covers the whole of its anterior surface, and is reflected on the lids so as to form their internal layer. It is continuous with the general gastro- pulmonary mucous membrane, and sympathises in its affections, as may be observed in various diseases. From the surface of the eye it may be traced through the lachrymal ducts into the lachrymal gland, along the edges of the lids it is continuous with the mucous lining of the Meibomian glands, and at the inner angle of the eye it may be followed through the lachrymal canaliculi into the lach- rymal sac, and thence downwards through the nasal duct into the inferior meatus of the nose. Where it covers the cornea the conjunctiva is thin, transparent, and inseparable from the corneal substance; it consists of stratified epithelial cells alone. In the conjunctiva at the circumference of the cornea a plexus of vessels is found, but this never extends entirely across the latter. The conjunctiva over the sclerotic is also thin and transparent, but is loosely applied and glides freely over the surface of the eyeball; it is freely supplied with blood by an irregularly disposed plexus of vessels. These vessels are readily distinguished from those of the sub-conjunctival tissue, as the latter radiate in nearly straight lines from the circumference of the cornea, and do not glide over the surface of the sclerotic on pressure. The sclerotic conjunc- tiva consists of stratified epithelium supported by a sub-epithelial layer, composed of white fibrous and elastic tissue, in the meshes of which numerous lymph corpuscles are seen. The palpebral conjunctiva is thick, opaque, and red ; it presents papillae on its surface, and very closely resembles ordinary mucous membrane in structure, but the papillae are limited to the part below the level of the tarsal plate. It consists of a stratified epi- thelium, supported by an elastic submucous tissue; in the latter, numerous simple follicles are found, and near the reflected portion, certain racemose glands, similar in structure to the lachrymal gland. Bruch has described masses of lymphoid tissue as occupying the conjunctiva of the fornix conjunctivas, and Henle has named these masses trachoma glands; it appears doubtful, however, if they are present in normal conditions of the conjunctiva. Between the eyelids and ball of the eye the conjunctiva forms an upper and lower fold, which are called the superior and inferior palpebral folds (retro-tarsal folds), the upper being the larger ; they are now frequently spoken of as the upper and lower fornix con- junctive. The caruncula lachrymalis is the small reddish body which occupies the lacus lachrymalis at the inner canthus of the eye. In health it presents a bright pink tint; in sickness it loses its colour 620 ORGANS OF SENSE. and becomes pale. It is studded with fine hairs, and consists of a dozen racemose sebaceous glands, with some few fat cells inter- mingled, a few fibres of unstriped muscle, and a covering of mucous membrane. Immediately to the outer side of the caruncula is a slight dupli- cature of the conjunctiva, called plica semilunaris ; it is simply a fold of conjunctiva, and is the rudiment of the third lid or mem- brana niditans of birds. Vessels and Nerves.—The eyelids and other appendages of the eye are supplied with blood by the nasal, palpebral, and lachrymal branches of the ophthalmic, and the angular branch of the facial artery. The nerves are derived from the facial and fifth nerves. The lachrymal apparatus consists of the lachrymal gland with its excretory ducts ; the puncta lachrymalia and lachrymal canaliculi; the lachrymal sac and nasal duct. The lachrymal gland is situated at the upper end and outer part of the orbit, in a depression of the orbital plate of the frontal hone, with the periosteum of which bone it is connected by fibrous bands ; by its under surface it is in relation with the globe of the eye, and the superior and external rectus muscles. It is oval in shape, about three-quarters of an inch long, convex on its upper and concave on its under surface. The anterior portion is frequently separated from the rest by a slight depression, and is then described as the palpebral portion (accessory gland of Ilosenmuller) ; it is situated in the upper eyelid, and extends downwards to the superior margin of the tarsal cartilage. The gland consists of a number of aggregated racemose glands similar in structure to the salivary and mucous glands. The secretion is conveyed away by from eight to twelve small ducts w-hich run for a short distance beneath the conjunctiva, and open on its surface by separate orifices, about a twentieth of an inch apart, the greater number in the fold above the outer canthus, and two of them in the fold below. The lachrymal canaliculi commence at the minute openings, puncta lachrymalia, seen on the lachrymal papillae of the lids at the outer extremity of the lacus lachrymalis, and proceed inwards to the lachrymal sac, where they terminate beneath a valvular semilunar fold of mucous membrane (valve of Husclike). The superior duct is the narrower and longer of the two ; it at first ascends and then suddenly turns inwards towards the sac, forming an abrupt angle. The inferior duct forms the same kind of angle by descending at first and then turning abruptly inwards. Both canals are dilated where they are bent. A valve-like projection (valve of Foltz) has been described as projecting from the side into the interior of the vertical portion of each canaliculus near the punctum lachrymale ; it seems to be sufficient to close the tube completely when it is flattened by the orbicularis and tensor tarsi muscles. It no doubt LACHRYMAL APPARATUS. GLOBE OF THE EYE. 621 prevents the tears being driven back when such pressure is applied, as in winking ; and as a consecpience they are then driven forward into the lachrymal sac. The two fasciculi of the tensor tarsi muscle are inserted into the canaliculi, and serve to draw them inwards and compress them. The lachrymal sac is the dilated upper extremity of the nasal duct. It. is lodged in the groove of the lachrymal bone, and is often distinguished internally from the nasal duct by a semilunar or cir- cular valve. The sac consists of mucous membrane, but is covered in and retained in place by a fibrous expansion, derived from the tendon of the orbicularis, which is inserted into the ridge on the lachrymal bone ; it is also covered by the tensor tarsi muscle, which arises from the same ridge, and when in action makes pressure on the lachrymal sac. The nasal duct is a short canal, about three-quarters of an inch in length, directed downwards, backwards, and a little outwards to the inferior meatus of the nose, into which it opens. It is lined by mucous membrane, which is continuous with the conjunctiva above, and with the pituitary membrane of the nose below ; it frequently forms an imperfect valve (valve of Hamer) at the lower opening of the duct. The mucous membrane of the canaliculi is covered by a stratified scaly epithelium, and that of the lachrymal sac and nasal duct by columnar ciliated cells. Vessels and Nerves.—The lachrymal gland is supplied with blood by the lachrymal branch of the ophthalmic artery, with nerves by the lachrymal branch of the ophthalmic, and the orbital branch of the superior maxillary. The globe or ball of the eye is irregularly spheroidal in form, having the segment of a smaller sphere (the cornea) projecting from it anteriorly, and being slightly flattened behind. Its transverse diameter is about 24 mm., the horizontal 23.5 mm., and the vertical 23.1 mm. Around the eyeball is a layer of fascia which separates it from the fat of the orbit, and enables it to move smoothly ; this is the so-called tunica vaginalis oculi, or capsule of Tenon; it is pierced by the tendons of the straight and oblique muscles, and is connected with the sclerotic by means of delicate fibrous threads. The globe of the eye is composed of a strong external fibrous coat, called the sclerotic, with its clear anterior portion, the cornea; a middle vascular and pigmentary covering, the choroid, which is also continued forwards to form a partition, the iris; and an internal nervous tunic, the retina. It encloses certain refracting media, for the purpose of bringing rays of light to a focus on the retina ; these are the vitreous and aqueous humour, and the crystalline lens. External Tunic.—Sclerotic.—The sclerotic (a-Khrjpds, hard) forms the outer covering of the posterior four-fifths of the globe of the GLOBE OF THE EYE. 622 OKGANS OF SENSE. eye. It is continuous posteriorly with the outer sheath of the optic nerve derived from the dura mater, and is pierced by the ciliary nerves and arteries. Anteriorly its fibres are continuous with the transparent ones of the cornea. It is thickest behind, but is strengthened in front by an expansion of the recti tendons, forming the tunica albuginea; this is covered for the greater part of its extent by the conjunctiva, and by reason of its brilliant whiteness gives occasion to the common expression, “the white of the eye.” I11 structure the sclerotic is found to consist of white fibrous tissue, with some few elastic fibres and a great number of stellar nucleated cells ; the fibres are arranged in bundles which run both longitudi- nally and transversely, the superficial layers being chiefly longitu- dinal. The inner surface of the sclerotic is in contact with the choroid, and is connected to it by means of numerous threads of Fig. 356.—General diagram of the eye. 1. Cornea. 1'. Corneal conjunctiva. 2. Sclerotic. 2'. Outer sheath of the optic nerve, which is seen to be con- tinuous with the sclerotic. 3. Vascular layers of the choroid. 3'. Pigmentary layer. 4. Radiating por- tion of the ciliary muscle. 4'. Cut fibres of circular portion, or muscle of Mul- ler. 5,5. Ciliary processes. 6. Posterior chamber of the aqueous humour. 7,7. Iris. 8. Optic nerve. 8'. Optic cumulus. 8'(. Yel- low spot. 9. Ora serrata. 10. Canal of Hannover. 11. Anterior chain her of the aqueous humour. 12. Crystalline lens. 13. Chamber of the vitreous humour. 14. Canal of Schlemm. r. Nervous layers of the retina, r'. Bacillary and molecular layers of the retina. fibrous tissue and by small vessels ; these being tinged with the pigmentary matter of the choroid have a brown appearance, and hence the term lamina fusca is applied. The lamina fusca is lined by a layer of endothelial cells and forms the outer wall of the peri- choroidal lymph space. At the entrance of the optic nerve a thin cribriform lamella, lamina cribrosa,* takes the place of the sclerotic ; it is pierced by a number of minute openings for the passage of the nervous filaments, and in the centre by a larger opening called porus opticus, for the entrance to the eyeball of the arteria cen- tralis retinae. The cornea (corneus, horny) is the transparent prominent layer which constitutes the anterior fifth of the globe of the eye. When * The lamina cribrosa is generally described as the continuation of the sclerotic, but it seems more probable (as Dr. T. Reid suggests) that it is continuous with the choroid ; indeed, in an inflamed eyeball the fibres of the lamina have been distinctly traced into the choroid. CORNEA. 623 examined from the exterior, its vertical diameter is seen to be about one-sixteenth shorter than its transverse, in consequence of the over- lapping above and below of the margin of the sclerotic ; on the in- terior its outline is circular. It is continuous with the sclerotic, and is connected with the iris, choroid, and ciliary processes. The thickness of the cornea is about one millimetre ; it is generally the same throughout, except at the periphery, where it becomes a little thinner. Structure.—The cornea is divisible into four layers ; these are, i. Conjunctival epithelium ; 2. Anterior limiting layer ; 3. Cornea propria ; and 4. Membrane of Descemet or Demours. The first of these has been already described. The anterior limiting layer (anterior elastic lamina of Bowman) is a transparent and apparently structureless layer, having an average thickness of from ttoW to t->W °f an dich ; it is devoid of laminae and corneal corpuscles, but otherwise is indistinguishable from the next layer, with which it is connected by fine threads running into the sub- stance of the latter. The cornea propria forms the bulk of the cornea. It consists of numerous layers of delicate transparent fibres, continuous externally with those of the opaque sclerotic; the fibres are collected into bundles, separated from each other by a ground substance similar to that in other connective tissues. Between the strata nucleated cells are found, which freely anasto- mose with each other, and appear to be stellate in sections made parallel to the surface of the cornea. The cells lie in spaces in the ground substance, which correspond to them accurately in size and shape. The spaces can be easily made out by painting the tissue with nitrate of silver ; they are generally held to be lymph channels. The membrane of Descemet or Demours forms the posterior layer of the cornea, and lines the chamber of the aqueous humour ; it con- sists of an elastic and an epithelial layer. The elastic layer (posterior elastic lamina of Bowman) is about -006 mm. in thickness ; it is highly elastic, and when partially de- tached tends to curl up. The epithelium consists of a single layer of irregularly shaped nucleated cells. At the edges, the membrane of Descemet breaks up into threads, some of which are continued on to the iris to form the ligamentum pectina- tum, others terminate in the inner wall of the canal of Schlemm, and some few are connected with the ciliary muscle. The pro- cesses which pass to the iris are covered by a single layer of cells of the same kind as those lining the membrane of Descemet, but, as the cells do not pass over the intervals between Fro. 357.— A vertical sec- tion of the cornea of an adult, showing the layers of which it is composed. 624 ORGANS OF SENSE. the strands, small apertures are left, called the spaces of Fontana, through which the anterior chamber communicates with the canal of Schlemm. MIDDLE TUNIC.—The second or middle tunic of the eyeball is formed by the choroid, ciliary muscle, and iris, the ciliary processes being appendages developed from its inner surface. The choroid (ydptoi/ elbos, like the 'chorion, that is to say, “ vas- cular ”) is of a rich chocolate-brown colour on its external surface, and of a darker tint within. It is connected to the sclerotic hv means of the line areolar tissue called lamina fusca, by vessels and nerves. Internally, it is in simple contact with the retina. It is pierced posteriorly for the passage of the optic nerve, and is connected ante- riorly with the iris, ciliary processes, and the line of junction of the cornea and sclerotic. The choroid is composed of three layers. The external layer is composed of line elastic fibres arranged in lamellae, and lined Fio. 358. — Dissection of tiie eyeball, showing its second tunic, and the mode of dis- tribution of the vense vorti- cosse of the choroid. 1. Part of the sclerotic coat. 2. Optic nerve. 3, 3. Choroid coat. 4. Ciliary ligament. 5. Iris. 6, 6. Venas vorticosse. 7, 7. Trunks of the vense vorticosse at the poi n t where they have pierced the sclerotic. 8, 8. Posterior ciliary veins, which enter the eyeball in company with the posterior ciliary arteries, by piercing the sclerotic at 9. 10. One of the long ciliary nerves, accompanied by along ciliary vein. with endothelium ; it forms lymph spaces, which are connected with the cavity of Tenon’s capsule. This layer is called the lamina supra-choroidea. The middle or venous layer consists principally of veins, the smaller branches of which are arranged in whorls (vasa vorticosa) round the chief trunks, four or five in number. Between the meshes of the veins are stellate pigmentary cells, which are con- nected together so as to form a fine web. The inner or arterial layer of the choroid or chorio-capillaris (tunica Ruyschiana) is formed principally of the ramifications of minute arteries, which form a complete network with very fine meshes. It is reflected inwards so as to form the ciliary processes. A structureless transparent membrane (membrane of Bruch) has been described as lying between the chorio-capillaris and the pig- mentary layer of the retina. At the junction of the sclerotic and cornea with the choroid and iris, a small venous canal is found, called the canal of Schlemm 625 (sinus circularis iridis); it communicates with the venous trunks of the choroid, and by the spaces of Fontana with the anterior chamber of the aqueous. This canal seems to be more constant in the lower animals than in man, and has been observed to be very large in the negro ; its place is frequently taken by several small veins. The iris (iris, a rainbow) is so named from its variety of colours in different individuals ; it consists of muscular and fibrous tissue with pigmentary cells, the latter being interspersed through- out the tissues, as well as forming a distinct posterior layer. The colour of the iris depends on the quantity and arrangement of the pigment cells ; when the cells are in small quantity they are chiefly confined to the poste- rior layers, and the iris as seen from the front has a blue colour ; but when in greater quantity, they are also dispersed through the tissues, and a grey or brown colour is the result. By its outer edge the iris is con- nected with the choroid and Sclerotic ; by its inner it forms the boundary of a circular opening called the pupil; its anterior surface looks towards the cornea and is free ; its posterior, looking towards the ciliary processes and lens, is in contact with them throughout greater part of its extent. The stroma of the iris consists of fibres of connective tissue intermixed with cells, the former being arranged radially towards the pupil and circularly near the outer margin. The cells are very numerous, and for the most part much branched ; many of them contain pigment, both in the body of the cell and in the processes. The muscular tissue is of the unstriped variety. It consists of two sets of fibres, one of which is disposed circularly round the aper- ture of the pupil, so as to form a sphincter, the contraction of which will diminish the size of the opening ; the other set is gathered into numerous bands which radiate from the pupillary margin to the circumference, and serve by their contraction to dilate the pupil. The pigmentary layer, situated on the posterior surface of the iris, is of a deep purple tint, and hence has received the name of uvea (like a grape); it is continuous with the inner layer of the choroid. It consists of deeply pigmented polygonal cells, and is Fio. 359.—Anterior segment of a transverse section of the globe of the eye, seen from within. 1. Divided edge of the three tunics : sclerotic, choroid (the dark layer), and retina. 2. Pupil. 3. Iris, the surface presented to view in this section being the uvea. 4. Ciliary processes. 5, The scalloped anterior border of the retina. 626 ORGAN OF VISION. generally thrown into folds or ridges when the pupil is moderately dilated. On its anterior surface the fibres of the iris have mingled with them some elastic fibres continuous with those of the membrane of Descemet, and are so arranged as to produce a festooned appearance. These festoons are very distinct in the eye of the ox and sheep; they form the ligamentum pectinatum. The epithelial cells of the membrane of Descemet are continued over the anterior surface of the iris. The blood-vessels of the iris are numerous, and their outer coat is intimately connected with the fibrous stroma ; the arteries are derived from the long and anterior ciliaiy arteries, and from the circulus iridis major of the ciliary processes. In the foetus a delicate vascular membrane closes in the pupil (mem- braha pupillaris) ; it disappears about the seventh or eighth month. The nerves come from the ciliary branches of the lenticular ganglion, and from the long ciliary branch of the nasal. After forming a plexus near the ciliary margin of the iris, they divide into twigs which are distributed to the muscular fibres and anterior sur- face. The ciliary pro- cesses are formed by the plication of the anterior part of the ciliary region of the choroid. They may be seen in two ways, either by removing the iris from its attach- ment to the choroid, when a front view of the processes will be obtained, or by making a trans- verse section through the globe of the eye, when they may be examined from behind, as in Fig- 359- They consist of about eighty triangular folds, about one-third of which are smaller than the rest, and are interspersed at irregular intervals. The summits of the larger processes have upon them smaller, secondary processes, varying greatly in their number, size, Pig. 360.—Ophthalmoscopic view of the fundus of the eye. A. Optic disc. 6, 6. Choroidal ring, c, c. Retinal arteries. d, d. Retinal veins, g. Arteria centralis retinae dividing. 7i. Venous radicles uniting to form a trunk, n. Inner side. t. Outer side. X.fPhysiological cup and lamina cribrosa. CILIARY MUSCLE. 627 and shape. They have much the same structure as the choroid, and are composed of a vascular network and an internal pigmentary layer. Their periphery is connected with the ciliary muscle ; the central border is free, and nearly reaches the circumference of the lens ; the anterior surface is continuous with the uvea : the posterior surface receives the folds of the suspensory ligament of the lens. Each of the larger folds measures about of an inch in length, and of an inch in depth. The ciliary muscle (formerly described as the ciliari/ ligament) is situated internally to the canal of Schlemm. It forms a greyish- white ring round the anterior part of the choroid, and is found to consist of unstriped muscular tissue, the fibres of which are con- nected in front with the inner surface of the sclerotic, and the fibres of the membrane of Descemet; they pass inwards and backwards, and are attached to the choroid opposite and beyond the ciliary pro- cesses. Besides these fibres there are others, situated more inter- Fig. 361.—Section through the ciliary processes and periphery of the iris. a. Radiating fibres of the ciliary muscle. 6. Circular fibres or muscle of Muller, c. Circular fibres surrounded by radiating fibres, d. Circular fibres by themselves. e. Muscular fibres shown in their connection with the corneo-sclerotic junction. /.Iris. g. Uveal tract, h. Ligamentum pectinatum. nally, at the base of the ciliary processes; these are disposed cir- cularly, and constitute the circular muscle of Muller (sphincter ciliaris). The circular fibres are most developed in hypermetropic eyes, and are very scanty or altogether absent in those which are myopic (Iwanoff). INTERNAL TUNIC.—This consists of the retina, with its con- tinuation forwards, called the pars ciliaris retinal. The retina is the inner nervous tunic of the eye, and that on which the images of external objects are produced. It is in contact by its external surface with the choroid, and by its internal surface with the hyaloid membrane of the vitreous humour. It is firmly attached to “the back part of the eye by means of the retinal artery and fibres of the optic nerve which enter it, hut is loosely applied to the inside of the choroid throughout the rest of its extent. It terminates anteriorly, a little behind the ciliary processes, in a festooned edge, the ora serrata; hut from this edge there are 628 ORGAN OF VISION. continued forwards over the ciliary processes to the base of the iris, some peculiar, elongated, nucleated cells, constituting the pars ciliaris retina. In the fresh eye the retina is of a pale pink colour, and is translucent, but it soon becomes opaque and yellowish, especially when in contact with fluids. At the back part of the retina, nearly in the axis of the eye, is a spot of a golden-yellow colour— macula lutea (called by Soemmering limbus luteus) ; it is elliptical in form, with a long diameter of about yb of an inch, and short diameter of an inch. In the middle of this is a depression, fovea centralis, where, the retina being thinned, the pigmentary matter of the choroid is seen through ; hence it has the appear- ance of being a fora- men, and was so de- scribed by Soemmering. This is the most sensi- tive spot of the retina, and being placed nearly in the axis of the eye, receives the image of that part of an object to which the eye is directed, and of which the most vivid impres- sion is obtained. About of an inch to the inner side of the macula is the entrance of the optic nerve. Here there is a slight elevation (colliculus nervi optici), with a cupped centre, perforated by the arteria centralis retinae ; the artery upon entering imme- diately breaking up into branches. This is the only part of the retina from which the power of vision is absent. The retina is thickest pos- teriorly, in the immediate vicinity of the optic nerve, where it has a thickness of of an inch, but it thins as it passes forwards, and near the ora serrata measures only r,^(T of an inch. Structure.—On the outer surface, the retina is formed by a single layer of hexagonal cells loaded with pigment, and constituting the Fig. 362.—Cells of the pars ciliaris retina;. Fig. 363.—Vertical section of the coats of the eye at the point of entrance of the optic nerve, d. Retina. e. Choroid. /. Sclerotic. art oftheseptum. It is situated between the aortic and left auriculo-ventricular openings. Position of the Heart in Relation to the Chest Wall. Two-thirds of the heart lie to the left of the middle line, only the right auricle lying to the right of it; its extreme limit to the right is about one inch from the border of the sternum, and to the left two and a half inches from the edge of that bone. The upper margin of the auricles corresponds to a line drawn from the second right to the first left intercostal space. The right auricle lies behind the lower part of the sternum, its outer edge being situate at about an inch to the outer side of the right border of the bone. The left auricle lies on the left of the sternum, in a line running from the second left inter- costal space to the upper border of the fourth left cartilage. The right ventricle extends from the third to the sixth cartilage of the left side near the sternum, the part nearest the surface being the conus arteriosus. The left border, formed by the left ventricle, may be defined by a line curved to the left, and extending from the edge of the sternum in the third left intercostal space, to the fifth space at about three and a half inches from the middle line The apex of the heart, also formed by the left ventricle, is situated behind the fifth intercostal space, about two inches below the nipple, and half an inch to its inner side. The right auriculo-ventricular opening (tricuspid valve) corresponds to the middle of the sternum, on aline with the fourth costal cartilages. The left auriculo-ventricular opening (mitral valve) lies behind the third intercostal space of the 66 9 left side at about an inch from the sternum. The 'pulmonary opening (pulmonary semilunar valves) is placed to the left of the sternum, on a level with the articulation of the third cartilage. The aortic open- ing (aortic semilunar valves) is placed lower than the pulmonary, and corresponds to the upper edge of the third intercostal space close to the sternum. The valves are so situated that the mouth of a stethoscope placed over the inner end of the third intercostal space of the left RELATION OF;HEART TO CHEST WALL. Fig. 389.— Position of the heart in relation to the chest wall, v, i. Innominate vein®. ao. Aorta, v, c. Vena cava superior, r. ait. Bight auricle. 1. att. Left auricle, r. v. Right ventricle. 1. v. Left ventricle. side will cover a portion of them ail (Holden). A needle introduced into the second right intercostal space close to the sternum, will pierce first the pleura and lung, then the pericardium, and next the ascending aorta ; introduced into the third, fourth, or fifth space of the right side, it will, after piercing the pleura and lung, enter the right auricle of the heart. 670 HEART. The heart is covered externally by a delicate serous membrane, the pericardium, and is lined within by another serous membrane, the endocardium; its walls consist for the most part of muscular fibres, forming the myocardium, with a considerable amount of fat, especially in the grooves on the surface, and beneath the pericardium. The large openings are surrounded by rings of fibrous tissue, and these are intimately connected with a fibro-cartilaginous mass situ- ated in the angle between the aortic and two auriculo-ventricular openings. STRUCTURE OF THE HEART. Muscular Structure. The muscular fibres of the heart have been already described in the section on Histology (p. 31); but their arrangement in the auri- cular and ventricular walls has still to be studied. Ventricles.—The fibres of the ventricles have a very intricate arrangement. They may be divided into seven layers, the fibres of which differ in direction. The fibres of the first layer run spirally downwards from left to right, but nearly vertically ; those of the second layer take the same general direction, but are more inclined to the horizontal; those of the third layer are still more transverse, and the fourth layer is quite traitsverse. Passing the fourth layer, which occupies a central position in the ventricular walls and forms the boundary between the external and internal layers, the order of arrangement is reversed and the fibres of the remaining layers, viz., five, six, and seven, gradually return in an opposite direction and in an inverse order to the same relation to the vertical as that maintained by the first external layer. The fibres composing corre- sponding external and internal layers, such as layers one and seven, two and six, &c., are continuous in the left ventricle at the apex, and in the right ventricle in the track for the anterior coronary artery, the fibres of both ventricles being for the most part continuous like- wise at the base. The fibres of the right and left ventricles anteriorly and septally are to a certain extent independent of each other; whereas posteriorly many of them are common to both ventricles ; i.e., the fibres pass from one ventricle to the other. At the apex the fibres are twisted round like a scroll or whorl, and then the external fibres enter into the interior of the ventricle, and some of them are continuous with those of the musculi papillares, others with the innermost layer of spiral fibres. The fibres from the back and front of the ventricle enter the apex in two different bundles, so that the whorl is composed of a double set of fibres twisted round each other something like the fingers of the two hands when they are folded over each other and closed. Auricles.—The muscular fibres of the auricles are disposed in three sets—transverse, spiral, and circular. The transverse are most ex- ternal ; they extend over both cavities and enter the septum. The spiral are attached at each extremity to the auriculo-ventricular MINUTE STRUCTURE. 671 rings ; they are looped and irregular in their arrangement, and are common to both auricles. The circular begin at the apex of the appendix and are continued on to the body of the auricle ; they have on their interior a number of fibres which are arranged longi- tudinally. The circular fibres belonging to each auricle are distinct from those of its fellow. Other fibres surround the entrance of the venae cavae and pulmonary veins and are continued for some distance along these vessels. The cardiac pericardium (epiccirdium), is a thin layer, composed of sub-serous areolar tissue formed by a network of tine elastic fibres, adherent by the deep surface to the muscular structure of the heart; this sup- ports on its free surface a single layer of polygonal endothelial cells, in the midst of which stomata are found, communicating with the sub-pericardial lymphatics. Beneath the pericardium, especially in the grooves of the heart, is more or less adipose tissue, which is sometimes distributed more ex- tensively over the surface of the organ. The endocardium, or lining membrane of the heart, is also thin, but thicker in the auricles than in the ventricles, and especially in the left auricle. It consists of three layers—namely, (i) a thin stratum of white fibrous areolar tissue, which connects it to the muscular structure ; (2) a middle layer, composed of elastic tissue, which is so abundant in the auricles as to constitute a fenestrated membrane; and (3) a layer of poly- gonal endothelial cells. Muscular fibres similar to those of the wall of the heart are also found in certain parts. In the ventricles the endocardium is transparent; in the auricles, particularly the left, it is opaque and white ; it is continuous with the lining membrane of the vessels which open into the heart. Beneath the endocardium of the ventricles in some animals, as the horse and sheep, peculiar beaded, reticulating fibres are found, and have been named the fibres of Purkinje. They are formed of large clear nucleated cells joined end to end, surrounded by granular material; the outer part of the cells shows evidences of transverse striation. They are believed to represent a stage in the develop- ment of the heart muscle, and are not present in the adult human heart. The auriculo-ventricular valves are composed of two layers of endocardium, connected in the body of the valve by areolo-fibrous tissue, mingled with a network of elastic fibres ; towards the edges of the valve, the two layers become blended with each other, and form a single membrane. Occasionally the muscular fibres of the heart wall are continued into these valves. The chordce tendinece Minute Structure. Fig. 390.—Endothe- lium of the endo- cardium. 672 HEART. consist of a fasciculus of tendinous fibres invested by a thin layer of endocardium. The semilunar valves are composed of a thin stratum of elastic and areolar tissue, the elastic tissue forming a fine network in the substance of the latter, and the free surface being invested by a single or double layer of endothelium. Vessels and Nerves.—The arteries of the heart are derived from the left and right coronary ; the capillaries form a fine network around the muscular fasciculi as in other muscles ; the veins accom- pany the arteries, and empty themselves by the common coronary vein into the right auricle ; the Thebesian and right cardiac veins discharging their blood directly into the auricle. The valves of the heart are non-vascular, with the exception of the auriculo-ventri- cular valves when they contain muscular fibre. Lymphatic vessels are scanty in the bag of the pericardium, but numerous beneath the visceral layer ; they follow the grooves of the heart, and terminate in the glands situated beneath the arch of the aorta, and upon the bifurcation of the trachea. The nerves of the heart are numerous, and derived from the cardiac plexuses, which are formed by filaments from the sym- pathetic and pneumogastric nerve, and reach the substance of the organ by means of the anterior and posterior coronary plexus. The nervous filaments partly accompany the vessels, partly cross their course, anastomose with each other at acute angles, and pierce the surface of the heart to reach its substance and the endocardium. The nerves are grey, being composed of fine pale fibres, a few only of the larger nerves containing in addition an admixture of medullated fibres. Where the nerve filaments intersect each other there are minute ganglionic enlargements, which receive the name of ganglia of Remak. Size and Weight of the Heart.—Roughly stated, the heart is about equal in size to the closed fist of the individual ; it measures about five inches in length, three and a half in greatest width, and two and a half in greatest thickness. The average weight of the heart in the male is eleven ounces, and in the female about nine ounces. Foetal Heart.—At the time of birth the heart is large in pro- portion to the size of the body ; the walls of the two ventricles are of nearly equal thickness, and are relatively thicker than in adult life ; the right and left auricles communicate by an oval opening, foramen ovale (Foramen of Botal). Both ventricles pour their blood into the aorta, this being accomplished in the case of the right ventricle by means of a trunk connecting the pulmonary artery with the junction of the transverse and descending parts of the arch, ductus arteriosus ; the Eustachian valve is large, and serves to prevent the blood from the inferior cava passing into the auriculo- ventricular opening, directing it into the foramen ovale. Foetal Circulation.—The pure blood is brought from the placenta Foetal Heart and Foetal Circulation. FCETAL CIRCULATION. 673 by the umbilical vein. The umbilical vein passes through the umbilicus and enters the liver, where it divides into several branches ; two or three of these branches are distri- buted to the left lobe, one branch communi- cates with the portal vein in the transverse fissure and supplies the right lobe, and a large branch, the duc- tus venosus, passes directly backwards and joins the inferior vena cava. In the inferior cava the pure blood becomes mixed with that which is returning from the lower extre- mities and abdominal viscera, and is carried through the right auricle (guided by the Eustachian valve) and through the foramen ovale into the left auricle. From the left auricle it passes into the left ventricle, and from the left ventricle into the aorta, whence it is distributed by means of the carotid and sub- clavian arteries, princi- pally to the head and upper extremities. From the head and upper extremities the impure blood is re- turned by the superior vena cava to the right auricle ; from the right auricle it is propelled into the right ventricle, and from the right ventricle into the pul- monary artery. In the adult, the blood would now be circulated through the lungs and oxygenated, but in the foetus the lungs are solid and almost impervious. Only a small quantity of blood passes therefore into the lungs, the greater part courses through the ductus arteriosus into the commencement of the descending aorta, where it becomes mingled with a very small portion of the pure blood derived from the left ventricle. Fig. 391.—Foetal circulation, a. Umbilical vein, b. Ductus venosus. c. Ductus artei-iosus. d. Hypogas- tric arteries, e. Termination of visceral arteries and commencement of portal system. f. Portal vein. The arrows show the course of the blood current. 674 FCETAL CIRCULATION. Passing along the aorta, a small quantity of this mixed blood is distributed by the external iliac arteries to the lower extremities ; the greater portion is conveyed by the hypogastric branches of the internal iliac arteries to the placenta ; the hypogastric arteries pass forwards by the side of the fundus of the bladder, and upwards along the anterior wall of the abdomen to the umbilicus, where they become the umbilical arteries. From a careful consideration of this circulation, we perceive—ist. That the pure blood from the placenta is distributed in considerable quantity to the liver, before entering the general circulation. Hence arises the abundant nutrition of that organ, and its enormous size in comparison with other viscera. cdly. That the right auricle is the scene of meeting of a double current; the one coming from the inferior cava, the other from the superior, and that they must cross each other in their respective courses. The inferior cava opens almost directly into the left auricle ; and, by the aid of the Eustachian valve, the current in the cava is almost entirely excluded from the right auricle. 3dly. That the blood which circulates through the arch of the aorta comes directly from the placenta; and although mixed with the impure blood of the inferior cava, yet is propelled in such abundance to the head and upper extremities, as to provide for the increased nutrition of those parts, and prepare them, by their greater size and development, for the functions which they are required to perform at the instant of birth. 4thly. That the blood circulating in the descending aorta is very impure, being obtained principally from the returning current in the superior cava; a small quantity only being derived from the left ventricle. Yet it is from this impure blood that the nutrition of the lower extremities is provided ; hence we are not surprised at their insignificant development at birth. 5thlv. That there are three places where a certain admixture of impure with purer blood occurs, viz., (i) at the junction of the ductus venosus and inferior cava, (2) in the right auricle, and (3) at the junction of the ductus arteriosus and aorta ; the first of these is the only important mixture. After birth, the foramen ovale becomes gradually closed by a membranous layer, which is developed from the margin of the opening on the left side and from below upwards, and completely separates the two auricles. The situation of the foramen is seen in the adult heart, on the septum auriculanun, and is called the fossa ovalis; the prominent margin of this opening is the annulus ovalis. As soon as the lungs have become inflated by the first act of inspiration, the blood of the pulmonary artery courses through its right and left branches into the lungs, to be returned to the left auricle by the pulmonary veins. Thus the pulmonary circulation is established. Then the ductus arteriosus contracts and degenerates into an impervious fibrous cord, serving in after-life simply as a LARYNX. 675 bond of union between the left pulmonary artery and the concavity of the arch of the aorta. The current through the umbilical cord being arrested, the hypo- gastric arteries likewise contract and become impervious. The umbilical vein and ductus venosus, also deprived of their circulating current, become reduced to fibrous cords, the former being the round ligament of the liver, and the latter a fibrous band which may be traced along the fissure of the ductus venosus to the inferior vena cava. ORGANS OF RESPIRATION AND VOICE. The organs of respiration are the two lungs, with their air-tube, the trachea, to the upper part of which is adapted an apparatus of cartilages, constituting the organ of voice, or larynx. THE LARYNX. The larynx is situated at the fore-part of the neck, between the trachea and base of the tongue. It is a short tube, of an hour-glass form, and is composed of cartilages, ligaments, muscles, vessels, nerves, and mucous membrane. The cartilages are nine in number, three of which are single and placed in the middle line ; the other six are arranged in three pairs placed symmetrically on each side. They are the— Thyroid, Cricoid, Two arytenoid, Two cornicula laryngis, Two cuneiform, Epiglottis. Tlie thyroid (dvpeos < ibos, like a shield) is the largest cartilage of the larynx: it consists of two lateral portions, or alae, which meet at an angle in front, and form the projection which is known by the name of pomum Adami. In the male, after puberty, the angle of union of the two alee is acute ; in the female, and before puberty in the male, it is obtuse. When the pomum Adami is prominent, a bursa mucosa is often found between it and the skin. Each ala is quadrilateral in shape, and forms a rounded border posteriorly, which terminates above, in the superior cornu, and below, in the inferior cornu ; the former pass upwards and slightly backwards, and are connected by means of the thyro-hyoid ligaments with the extremities of the greater cornua of the os hyoides; the latter curve downwards and inwards, and terminate by a smooth facet, by means of which they articulate with the lateral aspect of the cricoid cartilage. On the side of the ala is an oblique line, or ridge, directed downwards and forwards, and bounded at each ex- tremity by a tubercle. Into this line the sterno-thyroid muscle is inserted, and from it the thyro-hyoid takes origin ; the triangular area behind it gives attachment to the inferior constrictor of the 676 LARYNX. pharynx. In the receding angle, formed by the meeting of the two 'll®, on the inner side of the cartilage, and near its lower border, are attached the epiglottis, vocal cords, thvro - arytenoid and thyro - epiglot- tidean muscles. By its upper border the thyroid cartilage is connected with the hyoid bone by means of the thyro- hyoid membrane, its lower border being in like manner connected with the cricoid cartilage by the crico-thyroid membrane. The posterior border of each ala has attached to it the thyro- hyoid and palato-pliaryngeus muscles. The cricoid (KpiKos etdos, like a ring) is a ring of cartilage, narrow in front, and broad behind, where it is sur- mounted by two rounded surfaces, which articulate with the arytenoid cartilages. At the middle line, posteriorly, is a vertical ridge giving attachment to the oesophagus, and at each side of the ridge are the depressions which lodge the crico-arvtenoidei postici muscles, un einier siue 01 cue mig i* a glenoid cavity, which articulates with the inferior cornu of the thyroid cartilage. Its upper border gives attachment to the lateral crico-arytenoideus muscle and the crico- thyroid membrane, and its lower border is connected with the upper ring of the trachea by fibrous membrane. The arytenoid cartilages (dpvralva* a pitcher), two in number, nre triangular and nrismo’d in form. They are broad and thick below where they articulate with the upper border of the cricoid cartilage ; pointed above, and prolonged by two small pyriform fibro-carti- lages, cornicula laryngis (capitula Santorini), which are curved inwards and back- wards, and they each present three surfaces, posterior, in- ternal, and anterior. The posterior surface is concave, and lodges part of the arytenoideus muscle ; the internal surface is smooth, and forms part of the lateral wall of the glottis ; the anterior or external surface is rough and uneven, and gives attachment to the vocal cord, tliyro-arytenoideus, crico-arytenoideus lateralis Fig. 392.—Cartilages of the larynx. 1. Cricoid. 2. Thyroid. 3. Ary- tenoid cartilage. 4. Cornieulum laryngis. 5. Epiglottis. Fig. 393-—Right ary- tenoid, viewed from the outer side (twice the nor- mal size). 1. Mus- cular angle. 2. Vocal angle. 3. Transverse ridge. 4. Upper ridge, bor- dering fossa. 5. Tubercle. 6. Fossa. 7. Cornieulum la- ryngis. * This derivation has reference to the appearance of both cartilages taken together and covered by mucous membrane. In animals, which were the principal sub- jects of dissection among the ancients, the opening of the larynx, with the ary- tenoid cartilages, bears a curious resemblance to the mouth of a pitcher with a large spout. LIGAMENTS OF THE LARYNX. 6 77 and posticus. The outer angle is a stout prominent process, which gives attachment to the erico-arytenoideus posticus and crico-arytenoideus lateralis muscles, and hence has been named the processus muscularis; the anterior angle is a sharp and pointed process directed forwards ; it gives attachment to the inferior thyro- arytenoid ligament or true vocal cord, and has been named the processus vocalis. The cuneiform cartilages (cartilages of Wrisberg) are two small cylinders of yellow fibro-cartilage, about seven lines in length, and enlarged at each extremity. They lie in the aryteno-epiglottidean folds of mucous membrane. In the male, the cartilages of the larynx are more or less ossified, particularly in old age. The epiglottis (eViyXwrrty, upon the tongue) is a fibro-cartilage of a yellowish colour, studded with a number of small mucous glands, lodged in shallow pits on its surface. It is shaped like an obcor- date leaf, and placed immediately in front of the opening of the larynx, which it partly closes when the larynx is drawn up beneath the base of the tongue. It is attached by its point to the receding angle of the thyroid cartilage by means of fibrous tissue forming the thyro-epiglottic ligament, and to the inner surface of the body of the hyoid bone by the hyo-epiglottic ligament; with the base of the tongue it is connected by folds of mucous membrane forming the frenula. or glosso-epiglottidean folds, and with the summit of the arytenoid car- tilages by the aryteno-epiglottidean folds. Its laryngeal surface is concavo-convex from above downwards, and concave from side to side ; the convex portion projects into the anterior part of the upper opening of the larynx, and forms the cushion of the epiglottis. Ligaments.—The ligaments of the larynx are numerous, and may be arranged into four groups : i. Those which articulate the thyroid with the os hyoides. 2. Those which connect it with the cricoid. 3. Ligaments of the arytenoid cartilages. 4. Ligaments of the epi- glottis. 1. The ligaments which connect the thyroid cartilage with the os hyoides are three in number. Two thyro-hyoid ligaments pass between the superior cornua of the thyroid and the extremities of the greater cornua of the os hyoides ; they are composed of yellow fibrous tissue, and often con- tain a sesamoid bone or cartilage (cartilago triticea). The thyro-hyoid membrane is a broad membranous layer, occu- pying the entire space between the upper border of the thyroid cartilage and the upper and inner border of the os hyoides. It is pierced by the superior laryngeal nerve and artery. 2. The ligaments connecting the thyroid to the cricoid cartilage are also three in number :— Two capsular ligaments, with their synovial membranes, which form the articulation between the inferior cornua of the thyroid and the sides of the cricoid ; and the crico-thyroid membrane. The crico-thyroid membrane is a fan-shaped layer of yellow 678 LAKYNX. elastic tissue, thick in front (middle crico-thyroid ligament) and thinner at each side (lateral crico-thyroid ligament). It is attached by its apex to the lower border and receding angle of the thyroid cartilage, and by its expanded margin to the upper border of the cricoid and base of the arytenoid cartilages. Superiorly it is con- tinuous with the inferior margin of the vocal cords. The front of the crico-thyroid membrane is crossed by a small artery, the inferior laryngeal, and is the spot selected for the operation of laryngotomy. Laterally it is covered in by the crico-thyroid and lateral crico- arytenoid muscles. 3. The ligaments of the arytenoid cartilages are eight in number :— rI wo capsular ligaments, with synovial membranes, which arti- culate the arytenoid cartilages with the cricoid, strengthened behind Fio. 394.—Vertical section of the larynx, showing its ligaments. 1. Body of os hyoides. 2. Its great cornu. 3. Lesser cornu. 4. Ala of the thyroid cartilage. 5. Superior cornu. 6. In- ferior cornu. 7. Pomum Adami. 8, 8. Thyro- hyoid membrane ; the openingin the membrane immediately above the posterior figure is for the passage of the superior laryngeal nerve and artery, q. Thyro-hyoid ligament; the figure is placed immediately above the sesamoid cartilage, a. Epiglottis. b. Hyo-epiglottic ligament, c. Thyro - epiglottic ligament, d. Arytenoid cartilage ; inner surface, e. Outer angle of base of arytenoid cartilage. /. Corni- ctilum laryngis. g. Cuneiform cartilage, h. Superior thyro-arytenoid ligament, i. Inferior thyro-arytenoid ligament, or true vocal cord ; the elliptical space between the two thyro- arytenoid ligaments is the ventricle of the larynx. k. Cricoid cartilage. 1. Lateral portion of the crico-thyroid membrane, m. Central portion of the same membrane, n. Upper ring of trachea, o. Section of isthmus of thyroid body, p, p. Levator glandulse thyroideae. by two posterior crico-arytenoid bands or ligaments ; and the superior and inferior thyro-arytenoid ligaments. The superior thyro-arytenoid ligaments are two scattered bands of fibres attached in front to the receding angle of the thyroid cartilage, and behind to a tubercle on the anterior surface of each arytenoid cartilage, and contained in the folds of mucous membrane constituting the false vocal cords. The lower border of this liga- ment forms the upper boundary of the ventricle of the larynx. The inferior thyro-arytenoid ligaments, or true vocal cords, are thicker than the superior, and are composed of yellow elastic tissue. Each ligament is attached in front to the receding angle of the thyroid cartilage, and behind to the anterior angle of the base of MUSCLES OF THE LARYNX. 679 the arytenoid. The inferior border of the vocal cord is continuous with the lateral expansion of the crico-tliyroid ligament. The superior border forms the lower boundary of the ventricle of the larynx. The space between the two true vocal cords is the glottis or rima glottidis. 4. The ligaments of the epiglottis are five in number—namely, three glosso-epiglottic, hyo-epiglottic, and thyro-epiglottic. The glosso-epiglottic ligaments are three folds of mucous mem- brane, which connect the anterior surface of the epiglottis with the root of the tongue. The hyo-epiglottic ligament is a band of yellow elastic tissue passing between the anterior aspect of the epiglottis near its apex, and the upper margin of the body of the os hyoides. The thyro - epiglottic ligament is a long and slender fasciculus of yellow elastic tissue, which embraces the apex of the epiglottis, and is inserted into the receding angle of the thyroid cartilage immediately below the anterior fissure and above the attachment of the vocal cords. Muscles.—The intrinsic muscles of the larynx are nine in num- ber ; five of which are the muscles of the vocal cords and rima glottidis, and four are muscles of the epiglottis. The five muscles of the vocal cords and rima glottidis are— Crico-thyroid, Crico-arytenoideus posticus, Crico-arytenoideus lateralis, Thyro-arytenoideus, Arytenoideus. The crico-thyroid muscle arises from the anterior surface of the cricoid cartilage, and passes obliquely outwards and backwards to be inserted into the lower and inner border of the ala of the thyroid from its tubercle as far back as the inferior cornu. Some of its fibres are continuous with those of the inferior constrictor of the pharynx, and others with those of the crico-arytenoideus lateralis. The crico-arytenoideus posticus arises from the depression on the posterior surface of the cricoid cartilage, and passes upwards and outwards to he inserted into the muscular angle of the arytenoid. Its upper fibres are continuous with the lower fibres of the ary- tenoideus. The crico-arytenoideus lateralis arises from the upper border of the side of the cricoid, and passes upwards and backwards to be inserted into the muscular angle of the base of the arytenoid cartilage. The thyro-arytenoideus is situated above the preceding muscle ; it arises from the receding angle of the thyroid cartilage, close to the outer side of the true vocal cord, and passes backwards parallel with the cord, to be inserted into the base and outer and anterior surfaces of the arytenoid cartilage. Some observers describe the fibres of this muscle as being attached to the true vocal cord, spreading along its outer border ; tliis, however, is much disputed, and must be re- garded at present as not definitely proved. The arytenoideus muscle occupies the posterior concave sur- face of the arytenoid cartilages, between which it is stretched. It 680 LARYNX. consists of dee]) fibres arranged transversely, and passing between the arytenoid cartilages, and of two oblique bands crossing each other and continuous by their outer ends with the thyro - arytenoideus. The uppermost fibres run to the carti- lages of Santorini, and the lower ones blend with those of the tliyro- arytenoideus, and crico - arytenoideus lateralis (Kanthack). The four muscles of the epiglottis are — Thyro-epiglottideus, Aryteno-epiglottideus superior, Aryteno-epiglottideus inferior, Hyo-epiglottideus. The thyro-epiglottideus appears to be formed by the upper fibres of the thyro-arytenoideus muscle ; they spread out on the external surface of the sac- culus laryngis, and in the aryteno-epi- glottidean fold of mucous membrane, on which they are lost; a few of the anterior fibres being continued onwards to the side of the epiglottis (depressor epiglottidis). The aryteno-epiglottideus superior consists of a few scattered muscular fibres, which pass forward in the fold mucous membrane forming the late- ral boundary of the entrance into the larynx, from the apex of the arytenoid cartilage to the side of the epiglottis. The aryteno-epiglottideus inferior, closely connected with the sacculus laryngis, may be seen by raising the mucous membrane immediately above the ventricle of the larynx. It arises by a narrow and fibrous origin from the arytenoid cartilage, just above the attach- ment of the vocal cord ; and passing forwards and a little upwards expands over the upper half or two-thirds of the sacculus laryngis ; it is inserted by a broad attachment into the side of the epiglottis. The hyo-epiglottideus has not hitherto been described as a normal muscle of the human larynx. From the investigations, however, of Dr. John Macintyre in the dissecting-room of St. Mungo’s College, it would appear that it is invariably present, although varying much in the degree of its development. It generally consists of three muscular slips lying beneath the glosso- epiglottidean folds, and passing from the hyoid bone to the front of the epiglottis. The muscles of the larynx are so intimately connected with each other, that the separation into those above named and described is Fig. 395.—Posterior view of the larynx, i. Epiglottis. 2. Ary- teno-epiglottideus. 3. Superior cornu of thyroid. 4. Oblique fibres of arytenoideus. 5. Ary- teno-epiglottidean fold. 6. Deep fibres of arytenoideus. 7. Cor- niculum laryngis. 8. Mus- cular angle of arytenoid. 9. Thyroid cartilage. 10. Crico- arytenoideus posticus, n. Arti- culation of cricoid with thyroid. 12. Trachea. 13. Cricoid carti- lage. ACTIONS OF THE MUSCLES OF THE LARYNX. 681 in the main, artificial. The most distinct muscle is the crico-thyroid, and next to this the crico-arytenoideus posticus ; the others are so muted as to form a complete sphincter muscle, sphincter laryngis, which encloses the cavity of the glottis, and spreads out over the vocal cords and arytenoid cartilages, some of the fibres even reaching to the cornicula laryngis. Actions.—The crico-arytenoidei postici open the glottis while all the rest close it. The arytenoideus approximates the arytenoid cartilages posteriorly, and the crico-arytenoidei laterales and thyro- arytenoidei anteriorly ; the latter, moreover, close the glottis mesi- ally. The crico-thyroidei are tensors of the vocal cords, and these muscles, together with the thyro-arytenoidei, regulate the tension, position, and vibrating length of the vocal cords. The crico-thyroid muscles effect the tension of the vocal cords by rotating the inferior cornua of the thyroid on the cricoid; by this Fig. 396.—Side view of larynx, one ala of thyroid cut through and turned down. 1. Great cornu of hyoid. 2. Lesser cornu. 3. Cartilago triticea in thyro-hyoid ligament. 4. Body of hyoid. 5. Thyro-hyoid membrane. 6. Epiglottis. 7. Superior cornu of thyroid. 8. Front of thyro-hyoid membrane. 9. Corni- culum laryngis. 10. Aryteno-epiglottideus. 11. Arytenoideus. 12. Thyroid. 13. Muscular angle of arytenoid. 14. Thyro-arytenoideus. 13. Crico-arytenoideus posticus. 16. Crico-ary- tenoideus lateralis. 17. Articulation between inferior cornu of thyroid and cricoid (laid open). 18. Crico-thyroid (turned down). 19. Cricoid. 20. Lower part of right ala of thyroid (turned down). 21. Trachea. action the anterior portion of the thyroid is drawn downwards, and made to approximate the upper edge of the cricoid, thus separating it further from the arytenoid to which the vocal cords are fixed. The crico-arytenoidei postici separate the vocal cords by drawing the outer angles of the arytenoid cartilages outwards and down- wards. The crico-arytenoidei laterales, by drawing the outer angles of the arytenoid cartilages forwards, approximate the anterior angles to which the vocal cords are attached. The thyro-arytenoidei draw the arytenoid cartilages forwards, and, by their connection with the vocal cords, make the whole length or any segment of the cords tense. The thyro-epiglottideus acts principally by compressing the glands of the sacculus laryngis and the sac itself : by its attachment to the epiglottis it would act feebly upon that valve. The aryteno-epi- glottideus superior serves to keep the mucous membrane of the sides of the opening of the glottis tense, when the larynx is drawn 682 LARYNX. upwards and the opening closed by the epiglottis. 01 the aryteno- epiglottideus inferior, the functions appear to be, to compress the subjacent glands which open into the pouch ; to diminish the capa- city of that cavity, and change its form ; and to approximate the epiglottis and the arytenoid cartilage. Mucous Membrane.—The aperture of the larynx is a triangular or cordiform opening, broad in front and narrow behind ; bounded anteriorly by the epiglottis, posteriorly by the arytenoideus muscle, and on either side by a fold of mucous membrane stretched between the side of the epiglottis and the apex of the arytenoid cartilage. On the margin of this aryteno-epiglottidean fold the cuneiform cartilage forms a prominence more or less distinct. Between these folds and the ala of the thyroid, on each side, is a large fossa lined by mucous membrane, and named the hyoid or innominate fossa ; be- miu'i ing the superior and inferior laryngeal nerves communicate, and the branches of the superior and infe- rior thyroid arteries anastomose. The cavity of the larynx is divided into two parts by an oblong constriction pro- duced by the pro- minence of the vocal cords. That portion of the cavity which lies above the con- striction is broad and triangular above, and narrow below ; that which is below it, is narrow above and broad and cylindrical below, the circumference of the cylinder corresponding with the ring of the cricoid ; while the space in- cluded by the constriction is a narrow, triangular fissure, the glottis or rima glottidis. The form of the glottis is that of an isosceles triangle, bounded on the sides by the vocal cords and inner surface of the arytenoid cartilages, and behind by the arytenoideus muscle; the part of the chink of the glottis which lies between the vocal cords is often described as the vocalising area, and the smaller posterior portion as the respiratory area. Its length is greater in the male than in the female, and in the former measures somewhat less than an inch. Immediately above the prominence caused by the vocal cord, and extending nearly its entire length on each side of the cavity of the larynx, is an elliptical fossa, Fig. 397.—Vertical sec- tion of larynx, show- ing its ligaments. 1. Hyoid. 2. Epiglottis. 3 and 8. Thyro-hyoid membrane. 4. Great cornu of hyoid. 5. False vocal cord. 6. Tliyro-hyoid ligament. 7. Ventricle of larynx. 9. True vocal cord. 10. Aryteno - epiglottidean fold and cartilage of Wrisberg. n. Thyroid. 12. Superior cornu. 13. Crico - thyroid mem- brane. 14. Arytenoi- deus. 15. Trachea. 16. Arytenoid cartilage. 18. Cricoid. MUCOUS MEMBRANE. 683 the ventricle of the larynx. This fossa is hounded below by the true vocal cord, which it serves to isolate, and above by a border of mucous membrane folded upon the lower edge of the superior thyro-arytenoid ligament (superior or false vocal cord). The whole of the cavity of the larynx, with its prominences and depressions, is lined by mucous membrane, continuous superiorly with that of the mouth and pharynx, and prolonged interiorly through the trachea and bronchial tubes into the lungs. In the ventricles of the larynx the mucous membrane forms a csecal pouch of variable size, termed the sacculus laryngis. The sacculus laryngis is directed upwards, sometimes extending as high as the upper border of the thyroid cartilage, and occasionally above that border. When dis- sected from the interior of the larynx it is found covered by the aryteno-epiglottideus muscle and a fibrous membrane, which latter is attached to the superior thyro-arytenoicl ligament below ; to the epiglottis in front; and to the upper border of the thyroid cartilage above. If examined from the exterior of the larynx, it will be seen to be covered by the thyro-epiglottideus muscle. On the surface of its mucous membrane are the openings of sixty or seventy small race- mose glands, which are situated in the sub-mucous tissue, and give to its external surface a rough and ill-dissected appearance. The secretion from these glands is intended for the lubrication of the vocal cords, and is directed upon them by two small valvular folds of mucous membrane, which are situated at the entrance of the sacculus. The mucous membrane is closely connected to the epi- glottis and to the vocal cords, on the latter being remarkable for its thinness. It is invested by a columnar ciliated epithelium as high up as the superior folds of the ventricle of the larynx and lower half of the epiglottis, but on the true vocal cords the epithelium is squa- mous and non-ciliated. Glands.—The mucous membrane of the larynx is furnished with an abundance of mucous glands ; many of these are situated on the epiglottis, in the sacculus laryngis, and in the aryteno-epiglottidean folds, where they are termed arytenoid. The body known as the epiglottic gland is merely a mass of areolar and adipose tissue, situated in the triangular space between the front surface of the apex of the epiglottis, the hyo-epiglottic ligament, and the thyro- hyoid ligament. Laryngoscopic Appearance.—When examined by means of the laryngoscope, the upper opening of the larynx presents the appear- ance of a space of almost semilunar form, bounded in front by the base of the tongue and behind by the wall of the pharynx. In the anterior part of this space the curved free extremity of the epiglottis (Fig. 398, e) is seen, and projecting into the space from before, in the middle line, the cushion of the epiglottis (cu). I11 the middle line behind is a narrow slit, which is the space between the two arytenoid cartilages, and on each side of this a rounded tubercle, the tip of each corniculum laryngis ; a little externally to these, two other tubercles will be noticed, due to the presence of the cuneiform 684 TRACHEA. cartilages, and running from them outwards to the edges of the epiglottis, two crescentic folds of mucous membrane, the aryteno- epiglottidean folds. In the middle of the space, four flattened bands will be seen, two on each side; these are the true (ivc) and false (svc) vocal cords ; be- tween the former lies the narrow chink or fissure of the glottis. Vessels and Nerves.—The arteries of the larynx are derived from the superior and inferior thyroid. The nerces are the superior laryngeal and recurrent laryngeal ; both branches of the pneumo- gastric. The two nerves communicate with each other, but the superior laryngeal is distributed principally to the mucous mem- brane at the entrance of the larynx ; the recurrent to the muscles. Fig. 398.—Laryngo- scopic view of the glottis during the emission of a high note. e. Epiglot- tis. cu. Cushion of the epiglottis. ivc. True vocal cord. svc. False vocal cord. THE TRACHEA. The trachea or wind-pipe is cylindrical for about two-thirds of its circumference, and flattened on the posterior third, where it rests on the oesophagus ; it extends from opposite the upper border of the sixth cervical vertebra to opposite the fourth dorsal, where it divides into the two bronchi. The length of the trachea is about four inches (i i cm.), and its diameter from side to side nearly an inch (21 mm.) ; it is somewhat larger in the male than in the female. The right bronchus, lai'ger than the left, passes off nearly at right angles, to the upper part of the corresponding lung. The left descends obliquely, and passes beneath the arch of the aorta, to reach the left lung. The trachea is composed of cartilaginous rings, fibrous membrane, muscular fibres, elastic tissue, and is lined by mucous membrane. The cartilaginous rings are from fifteen to twenty in number, and extend for two-thirds around its cylinder, being deficient at the posterior part. The first ring is received within the lower margin of the cricoid cartilage, and is broader than the rest; the last is broad at the middle in consequence of the prolongation of the lower border into a triangular process which curves backwards at the point of bifurcation. The posterior extremities of the rings are rounded, and occasionally one or two rings will be found to bifurcate. The outer surface of each ring is flat, the inner is convex from above downwards. The fibrous membrane connects the rings and forms a thin covering to them on the outer surface. Internally it does not reach the surface, and the rings have in consequence on that aspect an appearance of greater prominence. It also stretches across between the rings on the posterior part of the trachea. The muscular fibres are disposed transversely across the space, TRACHEA. 685 between the extremities of the rings behind. They are placed internally to the fibrous membrane. Outside the circular fibres are a few running longitudi- nally : they are connected with the inner surface of the ends of the rings, and with the external fibrous mem- brane. The elastic tissue forms the submucous tissue, and is disposed in longitudinal bundles within the rings, and internally to the muscular layer behind. It is most developed opposite the bifurcation of the trachea. The mucous membrane, which is pale, forms the internal lining of the tube, and has opening upon its surface the excretory tubes of numerous mucous glands, the glands themselves lying external to the muscular coat; it is furnished with a ciliated columnar epithelium, continuous with that of the larynx above and the bronchial tubes below. Beneath the columnar cells and surround- ing their bases is a collection of small irregular cells (Debove’s layer), many of which become distended with mucus and form gohlet cells. The mucous membrane contains a large amount of lymphoid tissue. The mucous glands are small ovoid bodies situated between the fibrous membrane and the muscular layer behind, and in the sub- stance of the fibrous membrane between the rings. Their ducts open upon the mucous membrane. Nerves.—The nerves of the trachea are derived from the vagus and its recurrent branch ; they form a fine gangliated plexus on the outside of the muscular coat, the nerve filaments becoming non- medullated. The bronchi correspond very closely in structure with the trachea ; the cartilaginous rings are deficient behind, as in that tube ; there are usually six to eight rings in the right bronchus and ten to twelve in the left. The right bronchus is the more horizontal of the two, but it is shorter than the left ; it is larger, and is more directly continuous with the trachea, so that foreign bodies getting into the windpipe commonly pass into the right bronchus. The right gives off a branch above the pulmonary artery (eparterial bronchus) as well as branches below (hyparterial); the left gives off the latter only. Fig. 399.—Ciliated epithelium from the trachea. 1. External layer of longitudinal elas- tic fibres. 2. Base- ment membrane. 3. Round cells. 4. Oval and oblong cells. 5. Ciliated cells. THYROID BODY. The thyroid body consists of two lobes, placed one on each side of the trachea, and connected with each other by means of an isthmus, which crosses its upper rings, usually the third and fourth ; but in this respect there is some variety, a point necessary to be remembered 686 THYROID BODY. in operations on the trachea. The lobes are somewhat conical m shape, being larger below than above, and the smaller end is con- tinued upwards to the side of the thyroid cartilage. The isthmus is connected with the lower third of the two lobes, and often gives origin to a process of variable length and size, called the pyramid or third lobe. The pyramid is generally situated on the left side of the isthmus, and is often derived from the left lobe ; it is fre- quently connected with the hyoid bone by a muscular band, which receives the name of levator glandulee thyroidece. The left lobe is somewhat smaller than the right, the weight of the entire body being about one ounce and a half. It is, however, larger in young persons and females than in adult males, and undergoes a slight increase during menstruation. Its permanent enlargement consti- tutes bronchocele, goitre, or the Derbyshire neck. Structure.—The structure of the thyroid is of a brownisli-red colour, and is composed of a dense aggregation of minute and inde- pendent membranous cavities or vesicles en- closed by a plexus of capillary vessels, and connected together by areolar tissue. The vesicles are composed of a basement membrane lined by a columnar epithelium of nucleated cells, and contain a clear yellowish fluid, in which are found cells; the latter measuring , of an inch in diameter. Vessels and Nerves. —It is abundantly sup- plied with blood by the superior and inferior thyroid arteries. Some- times an additional ar- tery is derived from the arteria innominata, and ascends upon the front of the trachea to be distributed to the gland. The nerves are derived from the superior laryngeal and from the middle and inferior cervical ganglia of the sympathetic. The lymphatics are very numerous, and origi- nate for the most part in the connective tissue forming the stroma of the organ. Fin. 400.—Structure of the thyroid body. a. Con- nective-tissue stroma, b. Basement membrane, c. Epithelial cells. The lungs are two conical organs, situated one at each side of the chest, embracing the heart, and separated from eacli other by that organ and by an interspace, the mediastinum. On the external or THE LUNGS. LUNGS. 687 thoracic side they are convex, and correspond with the form of the cavity of the chest; internally they are concave, to receive the con- vexity of the heart. Superiorly they terminate in a tapering cone, which extends above the level of the first rib into the root of the neck, and interiorly they are broad and concave, and rest on the con- vex surface of the diaphragm. Their posterior border is rounded, broad, and long; the anterior, sharp, short, and marked by one or two deep fissures ; and the inferior border which surrounds the base is also sharp. The colour of the lungs is pinkish-grey, mottled, and variously marked with black. The surface is figured with irregularly polyhedral outlines, which represent the lobules of the organ, and the area of each of these polyhedral spaces is crossed by lighter lines representing smaller lobules. The weight of the lungs is about forty- two ounces, the right lung being twenty-two ounces and the left twenty; the ratio to the weight of the body is as i to 37 in the male and 1 to 42 in the female. Each lung is divided into two lobes by a long and deep fissure, called the great fissure, which extends from the posterior surface of the upper part of the organ downwards, and forwards to near the anterior angle of its base. In the right lung the upper lobe is sub- divided by a second fissure, which extends obliquely forward from the middle of the preceding to the anterior border of the organ, and marks off a small triangular lobe. The left lung presents a deep notch in its anterior border, at a point corresponding with the apex of the heart. The right lung is larger than the left, in consequence of the inclination of the heart to the left side. It is also shorter, from the great convexity of the liver, which presses the diaphragm upwards on the right side of the chest, considerably above the level of the left, and it has three lobes. The left lung is smaller, has only two lobes, but is longer than the right. The healthy lung is free at all parts of its surface, excepting along the lower two-thirds of the middle of its inner surface, where it is fixed, above by the root and below by a double layer of pleura called ligamentum latum pulmonis. The root is formed by the pulmonary artery, pulmonary veins, and divisions of the bronchus, together with the bronchial vessels, lymphatic vessels and glands, and pul- monary plexuses of nerves. The groove on the surface of the lung where the vessels enter its substance is the hilum pulmonis, and the position of the large vessels in the root of the lung, as follows : from before, backwards, they are placed in a similar order on both sides, viz. :— Pulmonary veins, Pulmonary artery, Bronchus. From above, downwards, the relative position of these structures is essentially the same on both sides, but on the right side there is an additional bronchus (eparterial), which is placed above the 688 LUNGS. pulmonary artery, consequently the arrangement on the two sides is as follows:— Ri_ht s ’ rEparterial bronchus, I Artery, | Hyparterial bronchus, l Veins. Artery, Hyparterial bronchus, Veins. Left, Relations of the Roots of the Lung.—1. Both lungs. In front, phrenic nerve and companion vessels, anterior pulmonary plexus. Behind, vagus nerve and posterior pulmonary plexus. Below, liga- mentum latum pulmonis. 2. Right lung alone. Above, vena azygos major. In front, superior vena cava. 3. Left lung alone. Above, arch of aorta. Behind, descending aorta. Structure of the Lungs. The lung is of a soft spongy texture, and, from its containing air, crepitates when squeezed between the fingers. Its specific gravity varies from .345 to .746. When cut, there exudes a frothy fluid consisting of mucus and blood intimately mixed with air. In the young child the lung is of a rose-pink colour, but in the adult it is much darker from the presence of pigment; in both, the surface is mottled, from the area over the centre of each lobule being lighter than that over the periphery. The surface is marked out into small polyhedral divisions, which are the outlines of the lobules. The lobules have their apices directed towards the centre of the lung, and their bases towards the surface ; they are largest at the surface of the lung, and smallest near its centre; they are connected with each other at their apices by the smallest bronchial tubes. Each lobule is a miniature lung, and consists of bronchial tube, pulmonary artery and vein, air cells supported by an elastic stroma, lymphatic vessels, and nerves. It is isolated from surround- ing lobules Tty areolar tissue derived from the subserous layer ; the entire lung is an assemblage of these lobules, so separated and so connected, held together by the pleura. The serous investing membrane of the lungs or pleura is con- nected with the surface of the lobules by means of a subserous areolar tissue, which forms a distinct layer, and being prolonged between the lobules, serves to unite them. This layer contains elastic tissue, and is a chief source of the elasticity of the lungs; in it a close plexus of capillary vessels is found, and numerous lymphatics, which communicate with the surface of the pleura by minute stomata. Bronchial Tubes.—The two bronchi proceed from the bifurcation of the trachea opposite the fourth dorsal vertebra to their correspond- ing lungs. The right, about an inch long, takes its course nearly at right angles with the trachea, passes behind the superior vena cava, and gives off a branch above the pulmonary artery (eparterial branch) to the upper lobe of the right lung : it then passes behind the arterv BRONCHIAL TUBES. 689 and gives off two otner branches below its level (hyf arterial branches), which pass to the middle and lower lobes. The left, two inches in length, and smaller than the right, passes obliquely beneath the arch of the aorta, and divides into two branches, both of which are placed below the pulmonary artery (liyparterial branches), and pass to the two lobes of the left lung. From this arrangement of the bronchi it seems probable that the two lower lobes of the right lung corre- spond to the whole of the left, and that the upper lobe of the right is entirely additional. Upon entering the lungs the bronchi divide into branches, and each of these divides and subdivides dicho- Fig. 401.—Heart and lungs, i. Right ven- tricle, the vessels to ttie left of the figure are the rigli t coronary artery and veins; those to its right, the left coronary ar- tery and veins. 2. Left ventricle. 3. Right auricle. 4. Lett auricle. 5. Pulmo- nary artery. 6. Right pulmonary artery. 7. Left pulmonary ar- tery. 8. Ligamentum arteriosum. 9. Arch of the aorta. 10. Superior vena cava. 11. Innominate ar- tery, and in front of it the right in- nominate vein. 12. Right subclavian vein, and, behind it, its corresponding ar- tery. 13. Right com- mon carotid artery and internal jugular vein. 14. Left inno- minate vein. 15. Left carotid artery and jugular vein. 16. Left subclavian vein and artery. 17. Trachea. 18. Right bronchus. 19. Left bronchus. 20, 20. Pul- monary veins ; 18, 20, form the root of the right lung; and 7, 19, 20, the root of the left. 21. Superior lobe of the right lung. 22. Middle lobe. 23. Inferior lobe. 24. Superior lobe of the left lung. 25. Inferior lobe. tomously to their ultimate termination in the intercellular passages and air-cells. The bronchial tubes or bronchioles are cylindrical tubes which differ from the bronchi in not being flattened posteriorly, and in having the cartilaginous and muscular layers distributed throughout their entire calibre. The cartilages cease to be regular rings and become irregular plates, which are most developed at the points of division of the bronchioles, where they form a concave ridge pro- jecting into the tube ; they disappear altogether when the tube is reduced to one millimetre in diameter. Connecting the cartilages and arranged outside them is a layer of fibrous tissue forming the fibrous coat; in the smallest tubes it is found devoid of cartilage, and becoming thinner is at length continued into the areolar stroma 690 LUNG. of the lobules. In this coat are numerous mucous glands, which send their ducts to open on the surface of the mucous membrane. Fig. 402.—Transverse section of the wall of a medium-sized bronchial tube. a. Fibrous layer containing plates of cartilage, mucous glands, &c. b. Muscular layer, c. Elastic sub-endotlielial layer, d. Columnar ciliated epithelium. The bronchial tubes continue to diminish in si/e until they attain a diameter of one millimetre, when they become changed in structure, and are continued onwards in the midst of air-cells, under the name of alveolar passages. These passages divide into smaller ones, which terminate by some- what dilated extremities, called infun- dibula, the walls of which are every- where crowded by hemispherical saccules called alveoli or air cells. The muscular fibres of the bron- chioles are non-striated ; they are ar- ranged in rings around the tube, and form a muscular coat which is placed internally to the cartilaginous plates and is continued as far as the plates themselves. The elastic fibres, ar- ranged in longitudinal fasciculi, form a thin stratum next the mucous lining ; this elastic coat is prolonged to the ends of the tubes, and scattered fibres are found around the alveolar passages and air-cells. The mucous membrane, lining the bronchial tubes, is provided with a ciliated columnar epithelium as far as their termination ; but in the alveolar passages and air-cells it is altered in its characters, is thin and transparent and coated with a squamous epithelium. Fig. 403.—A diagram showing the dilatation of the ultimate bronchial tubes into alveolar passages, and the enlargement of the latter near the surface of the lung, a, a. Bronchial tubes, b, b. Infundibula, on the walls of which are seen opening the air-cells, c, c. Air-cells near the surface of the lung. STRUCTURE OF THE BRONCHIAL TUBES 691 The air-cells are polygonal in form, and vary in diameter from .15 mm. to .35 mm.; they are smallest in the centre of the lung, and largest along the thin edges. Near the apex of the lobule the cells open singly into the alveolar passage, but at the base they are clustered, and several cells com- municate with each other before opening into the infundibulum. The wall of the air-cells is com- posed of the stromal tissue of the lung, formed in large part of yellow elastic tissue, with are- olar tissue and a few muscular fibres mixed. The white fibres are distinguished by numerous corpuscles scattered throughout them. The air-cells are lined by a single layer of epithelial cells, most of which are large fiat cell- plates without a nucleus, but there are others which are small, polygonal, and nucleated, and these are placed in groups of two or three cells over the interstices of the capillary plexus. The capillaries of the lungs form plexuses which occupy the walls and septa of the air-cells and the walls of the alveolar passages, but are not continued into the bronchial tubes. The capillary plexus in the wall of each air cell consists of a single layer of vessels, which is so disposed that it is ex- posed to the air con- tained in two contiguous air-cells. The air-cells of the central part of the lung are most vas- cular, and at the same time smallest, whilst those of the periphery are less vascular and larger. The pigmentary mat- ter of the lungs is contained in the walls of the air-cells, as well as in the areolar tissue of the inter-lobular spaces and blood-vessels ; it is composed chiefly of carbon. The pulmonary artery, conveying the dark and impure venous Fig. 404.—Two primary lobnli or infundi- bula. a, a. Exterior of lobules, b, b. Pulmonary vesicles. :c,y'c. Smallest bronchia. Fig. 405.—Arrangement of the capillaries of the human lung. 692 LUNG. blood to the lungs, accompanies the bronchial tubes to the lung, and divides as the tubes divide. The branches terminate in capillary vessels, which form a dense network in the parietes of the alveolar passages and air-cells, and then converge to form the pulmonary veins, bv which the arterial blood, purified in its passage through the capillaries, is returned to the left auricle of the heart. In their course through the lung, the artery is commonly found above and behind the bronchial tube, while the vein is below and in front. The bronchial arteries, branches of the thoracic aorta, ramify on the parietes of the bronchial tubes, and terminate partly in bron- chial veins which convey the venous blood to the vena azygos on the right side, and superior intercostal vein on the left; and partly in the pulmonary capillaries. The lymphatics on the surface of the lung form a fine sub-pleural plexus, communicating by means of stomata with the pleural cavity. Those in the substance of the lung consist of two sets, one of which forms an elaborate plexus beneath the mucous membrane of the bron- chial tubes, and the other originates in capillaries between the air-cells and alveolar passages. They all ter- minate in the bronchial glands at the root of the lung. These glands, very numerous and often o f large size, are placed at the roots of the lungs, around the bronchi, and at the bifurcation of the trachea. In early life they resemble lymphatic glands in other situations ; but in old age, and often in the adult, are black, and filled with carbonaceous matter, and occasionally with cal- careous deposits. The nerves are derived from the pneumogastric and sympathetic. They form two plexuses : anterior pulmonary plexus, situated upon the front of the root of the lungs, and composed chiefly of fila- ments from the deep cardiac plexus ; and posterior pulmonary plexus, on the posterior aspect of the root of the lungs,*composed principally of branches from the pneumogastric. The branches from these plexuses follow the course of the bronchial tubes, and are distributed to the intercellular passages and air-cells. Fig. 406.—Capillary network of an air cell. a. Capillary network. b. Terminal branch of the pul- monary artery encircling the cell. pleura: and mediastina. 693 PLEUKiE. Each lung is enclosed and its structure supported by a serous membrane, the pleura, which invests it as far as the root, and is then reflected on the parietes of the chest. That portion of the membrane which is in relation with the lung is called pleura pul- monalis, and that in contact with the parietes, pleura costalis. The pulmonary pleura is very thin, is elastic, and inseparably connected with the structure of the lung ; the costal pleura is thick and strong, has very little elasticity, and can be readily stripped off the ribs and intercostal muscles which it covers. The latter, besides forming the internal lining to the ribs and intercostal muscles, also covers the diaphragm and thoracic Surface of the vessels at the root of the neck, extending for somewhat more than an inch above the margin of the first rib. At the lower border of the root of the lung is a fold of the pleura, which extends down by the side of the posterior mediastinum to the diaphragm, and serves to retain the lower part of the lung in position. This fold is the broad ligament of the lung, lic/amentum latum pulmonis. At the right side, where the diaphragm is pressed upwards by the liver, the cavity of the pleura is shorter than on the left; while the left pleural cavity, in consequence of the encroachment of the heart on the left side of the chest, is narrower than the right. The right pleura extends at its anterior limit to the lower border of the seventh rib, in the axillary line to the ninth rib, and behind to the eleventh rib. The left pleura reaches to a lower level all round than the right; in the axillary line it touches the lower border of the tenth rib. MEDIASTINUM. The two pleural sacs do not communicate with each other, but have between them a space which contains all the viscera of the chest with the exception of the lungs. This is called the inter- pleural space or mediastinum. The mediastinum is divided into an anterior, middle, posterior, and superior portion. The anterior mediastinum is a triangular space, bounded in front by the sternum, triangularis sterni, sterno-liyoid, and sterno-thyroid muscles ; behind by the pericardium and the remains of the thymus gland, and at each side by the pleura. It contains a quantity of loose areolar tissue, in which are found some lymphatic vessels passing upwards from the liver, and mediastinal lymphatic glands. Dissection of the anterior mediastinum.—This space is best displayed by (i) dividing the sternum transversely on a level with the lower border of the first costal cartilages ; (2) dividing the same bone transversely between the fifth and sixth costal cartilages ; (3) cutting the sternum obliquely, commencing near the right end of the first cut, and terminating at the left end of the second. The two halves of the sternum can now be separated and the anterior mediastinum exposed. (Turner.) 694 MEDIASTINA. The middle mediastinum contains the heart enclosed in its peri- cardium, the ascending aorta, superior vena cava, pulmonary arteries and veins, bifurcation of the trachea, and phrenic nerves with their accompanying vessels. With the exception of the trachea and phrenic nerves, the whole of the contents of this space lie within the pericardium. The posterior mediastinum is bounded behind by the vertebral column, in front by the pericardium, and at each side by the pleura. It contains the thoracic aorta, the greater and lesser azygos veins, and superior intercostal veins, the thoracic duct, oesophagus, and pneumogastric nerves, the great splanchnic nerves, and some lym- phatic glands. The superior mediastinum is the part of the interpleural space which lies above the pericardium, and is bounded in front by the Fig. 407.—Transvei-se section of the thorax. 1. Anterior mediastinum. 2. Internal mammary vessels. 3. Triangularis sterni muscle. 4. Right phrenic nerve. 5. Left phrenic nerve. 6. Thoracic duct in posterior mediastinum. 7. (Esophagus with left vagus in front and right behind. 8. Vena azygos major. 9. Thoracic aorta giving off intercostal brandies. 10. Gangliated cord of sympathetic, r.v. Right ventricle, r.a. Right auricle, p. a.. Pulmonary artery, a. Aorta, c. Vena cava superior, v. Dorsal vertebra. sternum, and the origin of the sterno-hyoid and sterno-thyroid muscles, behind by the four upper dorsal vertebrae and longus colli muscle, and on each side by the pleura. It is bounded below by a plane passing from the junction of the first and second pieces of the sternum to the lower edge of the body of the fourth dorsal vertebra. It contains the remains of the thymus gland, the pneumogastric, cardiac, phrenic, and left recurrent laryngeal nerves ; the trachea, oesophagus, and thoracic duct; the transverse portion of the arch of the aorta, and its three great branches ; the superior intercostal veins ; THYMUS BODY. 695 the two innominate veins, commencement of the superior vena cava, and termination of the vena azygos major. THYMUS BODY. The thymus is a temporary organ, which is of large size in the young child, but in the adult is reduced so as to become a mere vestige ; it occupies the anterior mediastinum, and lies in relation with the pleurae and pericardium. In its mature state it consists of a thoracic and a cervical portion on each side. The former is situated in the anterior mediastinum, and the latter is placed in the neck just above the first bone of the sternum and behind the sterno-hyoid and sterno-thyroid muscles. It extends upwards from the fourth rib as high as the thyroid gland, resting against the pericardium, separated from the arch of the aorta and great vessels by fascia, and lying at each side of the trachea in the neck. Although described usually as a single mass, it consists actually of two lateral, almost symmetrical lobes, connected with each other by areolar tissue only, and having no structural communication ; they may therefore be properly called a right and left thymus body. The thymus is perceptible as early as the seventh week of em- bryonic existence, and continues gradually increasing with the growth of the foetus until the seventh month. At the eighth month it is large ; during the ninth it undergoes a sudden change, assumes a greatly increased size, and at birth weighs 240 grains. After birth it continues to enlarge until the expiration of the second year, when it ceases to grow, and begins to diminish between the eighth and twelfth year, being often well developed at the age of twenty, and only disappearing entirely before forty. The two lateral lobes of which it consists, are of an elongated pyramidal form, with their bases resting on the pericardium, and their apices reaching to the thyroid body. Each lobe consists of a number of polyhedral lobules, held together by- connective tissue, and enclosed in a fibrous capsule. The lobules, somewhat more than a quarter of an inch in dia- meter, are composed of smaller lobules, and the smaller lobules are made up of small round or polygonal solid masses, the nodules or follicles. These are in every respect similar in structure to the lymphoid masses found in other parts of the body, as, for instance, in the tonsils, and the solitary and agminate glands of the intestine. They consist of retiform tissue, the meshes of which are crowded with lymph corpuscles ; at the circumference of each nodule the retiform tissue is closer so as to form a sort of capsule. Scattered throughout the retiform tissue are peculiar, highly refracting corpuscles, which present an appearance of concentric striation, and have been named the concentric corpuscles of Hcissall. The arteries of the thymus gland are derived from the internal 696 ABDOMEN. mammary, superior thyroid, and inferior thyroid. The veins ter- minate in the left innominate vein, and some small branches in the thyroid veins. The nerves are minute, and derived chiefly, through the internal mammary plexus, from the superior thoracic ganglion of the sympathetic. Other branches reach the gland from the phrenic, pneumogastric, and descendens cervicis nerves. The lymphatics accompany the blood-vessels in the interior of the gland, terminate in the general union of the lymphatic vessels at the junction of the internal jugular and subclavian veins. ABDOMEN. The abdomen is the inferior cavity of the trunk of the body ; it is bounded in front, and at the sides, by the lower ribs and abdominal muscles ; behind, by the vertebral column and abdominal muscles ; Fig. 408.—Viscera of the abdomen in situ, i, 1. Flaps of the abdominal parietes turned aside. 2. Liver, its left lobe. 3. Right lobe. 4. Fun- dus of the gall-bladder. 5. Round ligament of the liver, issuing from the cleft of the longitu- dinal fissure, and pass- ing along the parietes of the abdomen to the umbilicus. 6. Part of the broad ligament of the liver. 7. Stomach. 8. Its pyloric end. 9. Commencement of the duodenum, a. Lower extremity of spleen. b, b. Greater omentum. c, c. Small intestines. d, Caecum, e. Vermi- form appendix. /. As- cending colon. g, g. Transverse colon. h. Descending colon. i. Sigmoid flexure of co- lon. k. Appendices epi- ploicae connected with the sigmoid flexure. I. Three ridges represent- ing the cords of the urachus and hypogastric arteries ascending to the umbilicus. m. Dia- phragm. above, by the diaphragm ; and below, by the pelvis; and contains the alimentary canal, the liver, pancreas, spleen, kidneys, and supra- renal capsules. Regions.—For convenience of description of the viscera, and of reference to the morbid affections of this cavity, the abdomen is REGIONS OF ABDOMEN. 697 divided into certain districts or regions. Thus, if two transverse lines be carried around the body, the one parallel with the cartilages of the ninth ribs, the other with the highest point of the crests of the ilia, the abdomen will be divided into three zones. Again, if a perpendicular line be drawn, at each side, from the cartilage of the eighth rib to the middle of Poupart’s ligament, the three primary zones will each be subdivided into three compartments or regions, middle and two lateral. The middle region of the upper zone being immediately over the small end of the stomach, is called epigastric (eVt yaarpp, over the stomach). The two lateral regions being under the cartilages of the ribs, are called right and left hypochondriac (biro yovSpoi, under the cartilages). The middle region of the middle zone is the umbilical; the two lateral, the lumbar. The middle region of the inferior zone is the hypogastric (vno yao-rpp, below the stomach); and the two lateral, the iliac. In addition to these divisions, we employ the term inguinal region, in reference to the vicinity of Poupart’s ligament. Position of the Viscera.—The position of the viscera which occupy these several regions may be best understood and remem bered, by arranging them in a tabular form, as follows :— Right Hypochondriac. Right lobe of liver, Hepatic flexure of co- lon, Upper end of kidney, Supra-renal capsule. Epigastric. Left lobe of liver, Part of right lobe, Gall-bladder, First and second parts of duodenum, Stomach, Pancreas, Part of spleen, Parts of both kidneys and supra-renal capsules. Left Hypochondriac. Great end of stomach, Spleen, Tail of pancreas, Splenic flexure of colon, Upper end of kidney, Supra-renal capsule. Right lumbar. Ascending colon, Lower part of kidney, Jejunum. Umbilical. Great omentum, Mesentery, Transverse colon, Transverse duodenum, Small intestines, Part of both kidneys. Left Lumhar. Descending colon, Lower part of kidney, Jejunum. Right Iliac. Caecum, Vermiform appendix, Ilium, Ureter. Hypogastric. Ilium, (Bladder and uterus when enlarged.) Left Iliac. Sigmoid flexure, Small intestines, Ureter. The peritoneum (irepiTeiveiv, to extend around) forms a completely shut sac, excepting in the female, where the peritoneum is perforated by the open extremities of the Fallopian tubes, and is continuous with their mucous lining. PERITONEUM. 698 The simplest idea that can be given of a serous membrane is, that it invests the viscus or viscera, and is then reflected on the parietes of the containing cavity. If the cavity contain only a single viscus, the consideration of the serous membrane is extremely simple. But in the abdomen, where there are a number of viscera, the serous membrane passes from one to the other until it has invested the PERITONEUM. Fig. 409. — Reflections of the peritoneum, d. Diaphragm. l. Liver. s. Stomach. c. Transverse colon, d. Trans- verse duodenum, p. Pancreas. 1. Small intestines, r. Rec- tum. b. Urinary bladder. 1. Anterior layer of perito- neum, lining the under sur- face of the diaphragm. 2. Pos- terior layer. 3. Coronary liga- ment, formed by the passage of these two layers to the posterior border of the liver. 4. Lesser omentum ; the two layers passing from the under surface of the liver to the lesser curve of the stomach. 5. The two layers meeting at the greater curve, then pass- ing downwards and returning upon themselves, forming (6) the greater omentum. 7. Transverse meso-colon. 8. Posterior layer traced up- wards in front of d, transverse duodenum, and p, pancreas, to become continuous with the posterior layer (2). 9. Fora- men of Winslow : the dotted line bounding this foramen inferiorly marks the course of the hepatic artery forwards, to enter between the layers of the lesser omentum. 10. Mesentery encircling the small intestines. 11. Recto- vesical fold, formed by the descending anterior layer. 12. Anterior layer traced up- wards on the inner surface of the abdominal parietes to the layer (1), with which the exa- mination commenced. whole, before it is reflected on the parietes. Hence its reflections are a little more complicated. In tracing the reflections of the peritoneum, in the middle line, we commence with the diaphragm, which is lined by two layers, one from the parietes in front, anterior, and one from the parietes behind, •posterior. These two layers of the same membrane, at the posterior part of the diaphragm, descend to the upper surface of the liver, forming the coronary and lateral ligaments of the liver. They then surround the liver, one going in front, the other behind that viscus, and meeting at its under surface, pass to the stomach, PERITONEUM. 699 forming the lesser omentum. They then, in the same manner, surround the stomach, and meeting at its lower border, descend for some distance in front of the intestines, and return to the transverse colon, forming the great omentum ; they then surround the trans- verse colon, and pass directly backwards to the vertebral column, forming the transverse meso-colon. Here the two layers separate ; the 'posterior ascends in front of the pancreas and aorta, and returns to the posterior part of the diaphragm, where it becomes the posterior layer with which we commenced. The anterior descends, invests all the small intestines, and returning to the vertebral column, forms the mesentery. It then descends into the pelvis in front of the rectum, which it holds in its place by means of a fold called meso- rectum, forms a pouch, the recto-vesical fold, between the rectum and the bladder, ascends upon the posterior surface of the bladder, forming its false ligaments, and returns upon the anterior parietes of the abdomen to the diaphragm, whence we first traced it. In the female, after descending into the pelvis in front of the rectum, it is reflected upon the posterior surface of the vagina and uterus. It then descends on the anterior surface of the uterus, and forms at either side the broad ligaments of that organ. From the uterus it ascends upon the posterior surface of the bladder, and anterior parietes of the abdomen, and is continued, as in the male, to the diaphragm. In like manner the peritoneum can be traced as a continuous sheet from one side to the other side of the abdomen. Thus, if we commence at the middle line in front and follow it across the ab- domen below the level of the transverse colon, we shall find that it passes from the abdo- minal wall to the right iliac fossa where it covers in the caecum and as- cending colon, forming the meso - caecum and ascending meso-colon ; it then passes in- wards and forms the mesentery which attaches the small intestines to the vertebral column, and may be traced from thence to the left iliac Fig. 410.—Transverse section of the abdomen at the level of the foramen of Winslow. The arrow passes from the greater to the lesser cavity of the peritoneum through the foramen of Winslow which is shown in section. 8. Stomach. P. Pancreas. Sp. Spleen. K. Kidney. V. Vertebra. A. Aorta. 700 PERITONEUM. fossa where it covers the sigmoid flexure (sigmoid meso-colon) ; it is then continued on to the abdominal wall, terminating at the point whence we set out. Abovethe transverse colon the arrangement is more complicated, in consequence of the existence of two cavities, a greater and a lesser. Beginning at the middle line we may trace the peri- toneum over the right kidney into the right hypochondrium ; it then passes across the body in front of the pancreas, and returns from left to right along the posterior surface of the stomach, so as to reach the foramen of Winslow, where it forms the posterior layer of the lesser omentum. It now becomes reflected on itself round the struc- tures (hepatic artery, portal vein, and common bile duct) forming the pillar of the foramen of Winslow, and constitutes the anterior layer of the lesser omentum. Passing over the anterior surface of the stomach, it is continued on the spleen, which it encloses (form- ing the gastro - splenic omentum), and so passes to the left hypochondrium, and from thence to the anterior wall of the abdomen. Processes of Peritoneum.—The folds of peritoneum serve the purpose of connecting the viscera with the abdominal wall or with each other, and thus limiting their movement. Those attached to the stomach are called omenta {greater, lesser, and gastro-splenic) ; those attaching the hollow viscera to the wall have the prefix meso-, as mesentery, meso-colon, meso-csecum, meso-sigmoid, &c. ; other folds more limited in extent receive the name of ligaments, such as those of the liver, stomach, urinary bladder, and uterus. The following is a brief description of these processes :— The lesser omentum (gastro-liepatic) is the duplicature which passes between the liver and the upper border of the stomach. It is extremely thin, excepting at its right border, where it is free, and contains between its layers the— Hepatic artery, Common bile duct, Portal vein, Lymphatics, These structures are enclosed in a loose areolar tissue called Glis- soti’s capsule. The relative position of the three vessels is, the artery to the left, the duct to the right, the vein between and behind. If the finger he introduced behind the right border of the lesser omentum, it will be situated in an opening called the foramen of Winslow. In front of the linger will lie the right border of the lesser omentum, containing the hepatic artery, portal vein, and hepatic duct; behind it, the right crus of the diaphragm and in- ferior vena cava covered by the ascending or posterior layer of the peritoneum ; below, the hepatic artery, curving forward from the coeliac axis, and the ascending portion of the duodenum ; and above, the lobus Spigelii. These, therefore, are the boundaries of the fora- men of Winslou), which is nothing more than a constriction of the general cavity of the peritoneum at this point, arising out of 1 he Hepatic plexus of nerves. necessity for the hepatic and gastric arteries to pass forwards from the cudiac axis to reach their respective viscera. If air be blown through the foramen of Winslow, it will descend behind the lesser omentum and stomach to the space between the descending and ascending pair of layers, forming the great omen- tum. This is sometimes called the lesser cavity of the peritoneum, and that external to the foramen the greater cavity ; in which case the foramen is considered as the means of communication between the two. It may be objected to this division that it tends to lead the inexperienced to believe that there are two cavities, while, in reality, there is but one, the foramen of Winslow being merely a constriction of that one, to facilitate the communication between the nutrient arteries and the viscera of the upper part of the abdomen. The great omentum (gastro-colic) consists of four layers of peri- t oieum, the two which descend from the stomach, and the same two, returning upon themselves to the transverse colon. A quantity of adipose substance is deposited around the vessels which ramify through its structure. In the foetus and young child, and occa- sionally in the adult, it is possible to separate the ascending layers of the great omentum from the transverse colon, and to trace them to the vertebral column on the upper surface of the transverse meso- colon, with which, however, they are only loosely connected. Under these circumstances the latter fold is formed by a separate dupli- cature of the peritoneum, and is not the direct continuation of the omentum, as in the description above given. The transverse meso-colon {pea-os, middle, being attached to the middle of the cylinder of the intestine) is the medium of con- nection between the transverse colon and the posterior wall of the abdomen. It affords to the nutrient arteries a passage to reach the intestine, and also forms a transverse septum across the abdominal cavity. On reaching the posterior wall of the abdomen, its two layers separate from each other on the anterior aspect of the trans- verse duodenum, the one ascending to cover in the pancreas, kidneys, and supra-renal capsules, and to pass from thence to the under surface of the diaphragm, the other descending to form the mesentery, and then passing into the pelvis. The mesentery {peaov evrepov, connected to the middle of the cylinder of the small intestine) is the medium of connection between tlie small intestines and the posterior wall of the abdomen. It is very narrow at its vertebral edge, measuring usually about six inches, while on its visceral border it measures from fifteen to eighteen feet; it thus presents the appearance of a gigantic fan folded on itself. It is oblique in direction, being attached to the posterior wall, from the left side of the second lumbar vertebra to the right iliac fossa ; retains the small intestines in their place, and contains between its folds the mesenteric arteries, veins, nerves, lymphatic glands, and lacteal vessels. The meso-rectum, in like manner, retains the rectum in con- PERITONEUM. 701 702 PERITONEUM. nection with the front of the sacrum. Besides this, there are some minor folds in the pelvis, as the recto-vesical fold, the false liga- ments of the bladder, and the broad ligaments of the uterus. The ligaments of the liver, uterus, and urinary bladder will be fully discussed in the description of those organs. The appendices epiploicse are small irregular pouches of the peritoneum, filled with fat, and attached like fringes to the colon, and upper part of the rectum. Three other duplicatures of the peritoneum are situated in the sides of the abdomen ; they are the gastro-phrenic ligament, the gastro-splenic omentum, the ascending and descending meso-colon, and the costo-colic ligament. The gastro-phrenic ligament is a small duplicature of the peritoneum, which descends from the diaphragm to the extremity of the oesophagus, and lesser curve of the stomach. The gastro-splenic omentum (ligamentum gastro- lienale) is the duplicature which connects the spleen to the stomach. The ascending meso-colon is the fold which connects the upper part of the ascending colon with the posterior wall of the abdomen ; and the descending meso-colon, that which retains the sigmoid flexure in connection with the abdominal wall. The costo-colic ligament (sustentaculum lienis) is a fold of peritoneum which stretches from the diaphragm about the level of the tenth or eleventh rib on the left side, to the splenic flexure of the colon ; it supports the spleen. Review of the Relations of the Peritoneum to the Abdomi- nal Viscera.—The liver is entirely covered by peritoneum, excepting a triangular area on its upper surface, where the coronary and falci- form ligaments meet, and its posterior border, including the lobus Spigelii. The stomach may lie considered as practically entirely covered by peritoneum, but Cathcart has pointed out that there is a triangular area at the back where it rests against the left crus of the diaphragm which is uncovered. The spleen is entirely covered. The ascending duodenum and the whole of the jejunum and ilium are entirely enveloped ; the descending and transverse parts of the duodenum are covered only in front. The transverse colon has peritoneum all round it. The ascending and descending portions vary in their arrangement; the caecum is usually completely covered so that there is a meso-csecum, and the same thing is true of the sigmoid flexure, a meso-sigmoid being generally present. The ascending and descending parts of the large bowel are commonly covered only in front, but in many cases the descending colon has a meso-colon and is thus completely covered, and in less frequent examples the ascending colon is in the same condition. The upper part of the rectum has a meso-rectum ; the part below this is covered only on the front and sides ; the next part has peritoneum only in front, and the last has no relation to that membrane. The pancreas, kidneys, and supra-renal capsules are covered only in front. The relation of the peritoneum to the pelvic organs will be considered when the organs themselves are described. ALIMENTARY CANAL. 703 ALIMENTARY CANAL. The alimentary canal is a musculo-inembranous tube, extending from the mouth to the anus. It is variously named in the different parts of its course, and is divided into the— Mouth, Pharynx, (Esophagus, Stomach, Duodenum, Jejunum, Ileum, ' Caecum, Colon, Rectum. Small intestine Large intestine The mouth, is the irregular cavity which contains the organ of taste and the principal instruments of mastication. It is bounded in front by the lips ; on each side by the internal surface of the cheeks ; above, by the hard palate and teeth of the upper jaw ; beloiv, by the tongue, the mucous membrane stretched between the arch of the lower jaw and the under surface of the tongue, and by the teeth of the inferior maxilla ; and behind by the soft palate and fauces. The lips are two fleshy folds formed externally by integument and internally by mucous membrane, and containing between these two layers, muscles, a quantity of fat, and numerous small labial glands. They are attached to the surface of the upper and lower jaw, and each lip is connected to the gum in the middle line by a fold of mucous membrane, the frena or frennla. The cheeks are continuous with the lips, and form the sides of the face ; they are composed of integument, a large quantity of fat, muscles, mucous membrane, and buccal glands. The mucous membrane lining the cheeks is reflected above and below on the sides of the jaws, and is attached posteriorly to the anterior margin of the ramus of the lower jaw. At about its middle, opposite the second molar tooth of the upper jaw, is a papilla, on which may be observed a small opening, the aperture of the duct of the parotid gland (Stenson’s duct). The hard palate is a dense structure, composed of mucous mem- brane, palatine glands, areolar tissue, vessels, and nerves, and firmly connected to the palate processes of the superior maxillary and palate bones. It is bounded in front and at each side by the alveolar processes and gums, and is continuous behind with the soft palate. Along the middle line it is marked by an elevated raphe, and pre- sents at each side of the raphe a number of transverse ridges and grooves. Near its anterior extremity, and immediately behind the middle incisor teeth, is a papilla which corresponds with the ter- mination of the anterior palatine canal, and receives the naso-palatine nerves. The gums are composed of a thick and dense mucous membrane, which is closely adherent to the periosteum of the alveolar processes, 704 TONGUE. and embraces the necks of the teeth. They are remarkable for their hardness and insensibility, and for their close contact, without ad- hesion, to the surface of the tooth. From the neck of the tooth they are reflected into the alveolus and become continuous with the periosteal membrane of that cavity (alveolo-dental membrane). The tongue has been already described as an organ of sense ; it is invested by mucous membrane, which is reflected from its under Fig. 411.—Median section of mouth, nose, pharynx, and larynx, o. Septum of nose ; below it, section of hard palate, b. Tongue, c. Section of velum pendulum palati. d, d. Lips. u. Uvula, r. Anterior pillar of fauces, i. Posterior pillar. t. Tonsil, p. Pharynx, h. llyoid bone. k. Thyroid cartilage, n. Cricoid carti- lage. s. Epiglottis. 1. Posterior opening of nares. 3. Isthmus faucium. 4. Upper opening of larynx. 5. (Esophagus. 6. Eustachian tube. part upon the inner surface of the lower jaw, and constitutes, with the muscles beneath, the floor of the mouth. On the under surface of the tongue, near its anterior part, the mucous membrane forms a considerable fold, which is called the fraenum linguae, and on each side of the fraenum is a large papilla, cnruncula sublingualis, the termination of the duct (Wharton’s duct) of the submaxillary gland. Running back from this papilla is a ridge occasioned by the SOFT PALATE. prominence of tlie sublingual gland, and opening along tlie summit of this ridge a number of small openings, the apertures of the excre- tory ducts (ducts of Rivinus) of the gland. Posteriorly the tongue is connected with the os liyoides by muscle, and to the epiglottis by three folds of mucous membrane, the glossoepiglottic folds. The soft palate (velum pendulum palati) is a fold of mucous membrane situated at the posterior part of the mouth. It is con- tinuous, superiorly, with the hard palate, and is composed of a double fold of mucous membrane, containing muscles, glands, and blood- vessels ; it is concave towards the mouth and convex towards the pharynx, and presents a free festooned edge interiorly. The structures forming the soft palate may be briefly summed up as follows Muscles: Two levatores palati, two tensores palati, two palati glossi, two palati pliaryngei, azygos uvulae. Palatine aponeurosis. Palatine glands. Arteries: Ascending palatine, descending palatine, palatine branch of ascending pharyngeal. Nerves: Descending palatine and external palatine from spheno- palatine ganglion. The mucous membrane is continuous with that of the hard palate, but is thinner and darker, and is covered by stratified squamous epithelium, ex- cepting at the extreme upper part of its posterior surface, near the opening of the Eustachian tube, where it is columnar and ciliated. The palatine glands are most numerous on the posterior surface of the velum and covering the uvula ; they are small compound race- mose glands. Hanging from the middle of the inferior border of the soft palate is a small rounded process, the uvula, and passing outwards from the uvula at each side are two curved folds of the mucous membrane, the arches or pillars of the fauces. The anterior pillar is continued downwards to the side of the base of the tongue, and is formed by the prominence of the palato-glossus muscle. The posterior pillar is prolonged downwards and back- wards into the pharynx, being formed by the convexity of the palato-pharyngeus muscle. These two pillars, closely united above, are separated below by a triangular interval or niche, in which the tonsil is lodged. The space included between the soft palate and the root of the tongue is the isthmus of the fauces. It is bounded above by the soft palate, on each side by the pillars of the soft palate and tonsil, and below by the root of the tongue. It is the opening between the mouth and pharynx. The tonsils (amygdala;) are two glandular organs, about half an inch in length, shaped like almonds, and situated between the anterior and posterior pillar of the soft palate, at each side of the fauces. Externally, they are invested by the pharyngeal fascia, which separates them from the superior constrictor muscle and internal carotid artery, and prevents an abscess from opening in that direction ; they correspond in position to the angles of the lower jaw, behind which they may he felt when enlarged. They present on their surface the openings of twelve to fifteen mucous crypts, similar to those at the root of the tongue and described below under 706 GLANDS OF MOUTH. the name of lingual glands. The substance of the tonsil is formed of a great number of lymphoid nodules, with some looser reticular tissue between them. The mucous glands of the mouth are racemose glands ; they are yellowish or whitish in colour, rounded in form, and situated in the submucous areolar tissue. The labial glands vary in size from half a line to one line and a half in diameter, and form an almost continuous layer around the mouth. The buccal glands are numerous, but smaller than the labial; a few of larger size being located near the aperture of Stenson’s duct. The molar glands are placed between the masseter and buccinator, and pierce the latter with their ducts opposite the molar teeth. The palatine glands are situated in the posterior half of the hard palate and in the soft palate ; in the latter forming a layer several lines in breadth. They are also numerous but small on the pos- terior part of the soft palate. The lingual glands form a thick stratum in the submucous tissue beneath the mucous crypts at the root of the tongue ; the layer of glands extends completely across the tongue, and their ducts, several lines in length, open by infun- dibuliform expansions, some into the mucous crypts, others into the foramen caecum, others into the fossa? of the papillae circum- vallatae, and others between the papillae. They are surrounded by a large quantity of lymphoid tissue which is here and there collected into round masses called lymphoid nodules, many of these being grouped around the cavities of the mucous crypts. Mucous glands are also dispersed on other parts of the tongue, but are smaller and few in number: a small group is found between the vertical folds on 1he sides of 1he Fio. 412.—Vertical section of the tonsil. 1. Hilus with vessel entering it. 2. Epi- thelial external layer. 3. Mucous crypt. 4. Lymphoid nodule. 5. Submucous tissue of the fauces terminating in the tonsil. 6. Interstitial connective tissue. Flo. 413.—Mucous crypt from the root of the tongue. i, 1. Epithelium. 2, 2. Papilhe of the mucous mem- brane. 3. Ca- vity of the crypt. 4. In- vesting coat of the gland, com- posed of areolar tissue. 5, 5. Fibro - vascular matrix, form- ing the paren- chyma of the crypt; and con- taining, 6, 6, Lymphoid no- dules surround- ing the crypt. SALIVARY GLANDS. 707 tongue, and a considerable group on its under surface near the tip and on either side of the frsenum linguae. SALIVARY GLANDS. Communicating with the mouth are the excretory ducts of three pairs of salivary glands—the parotid, submaxillary, and sublingual. The PAROTID GLAND (7rapa, near ; ovs, corns, the ear), the largest of the three, is situated immediately in front of the external ear, and extends superficially for a short distance over the masseter muscle ; on its deep aspect it is projected inwards by two processes, one of which lies between the styloid and mastoid processes, and tills up the back part of the glenoid cavity {glenoid lobe) ; the other passes in front of the styloid process {'pterygoid lobe). It reaches interiorly to below the level of the angle of the jaw, and posteriorly to the mas- toid process, slightly overlapping the insertion of the sterno-mastoicl muscle. It is separated from the submaxillary gland by the stylo- maxillarv ligament. Embedded in its substance are—the external carotid artery, temporo-maxillary vein, and facial nerve ; emerging from its anterior border, the transverse facial artery and branches of the facial nerve, and above, the temporal artery and auriculo- temporal nerve. On its posterior border lies the great auricular nerve, from which it receives branches. The duct of the parotid gland (Stenson’s duct), about two inches in length, and about the diameter of a crow’s quill, issues from the anterior part of the gland, just below the zygoma, and crosses the masseter muscle ; it then curves inwards over the anterior border of the muscle, and pierces the buccinator opposite the second molar tooth of the upper jaw ; its course through the mucous mem- brane of the cheek is very oblique, so that the posterior border of its opening forms a valvular fold, which prevents fluid from passing from the mouth into the duct. The course taken by the duct may be roughly indicated by a line drawn from the bottom of the lobule of the ear to a point midway between the mouth and nose. The duct is dense in structure, and its walls of considerable thickness in proportion to the area of the tube, which is remarkably small. A small glandular appendage, the soda parotidis, is connected with the upper part of the duct on the masseter muscle ; and opens into it by one or several small ducts. The SUBMAXILLARY GLAND, rounded in its form, is situated in the posterior part of the submaxillary triangle of the neck. It rests on the hyo-glossus, stylo-glossus, and mylo-hyoicl muscles, and is covered in by the body of the lower jaw and the deep cervical fascia. It is separated from the parotid gland by the stylo-maxillary ligament, and from the sublingual gland by the mylo-hyoid muscle. Embedded among its lobules are the facial artery and submaxillary ganglion. Its excretory duct, Wharton’s duct, about two inches in length, issues from the middle of the gland, and passes between the mylo- 708 SALIVARY GLANDS. hyoid and hyo-glossus to the fraenum linguae, by the side of which it terminates at the apex of a papilla, caruncula sublingualis. A process of the gland is pro- longed with the duct for a short distance above the mylo-hyoid. The SUBLIN- GUAL is a long and flattened gland, situated be- neath the mucous membrane of the floor of the mouth, at the side of the fraenum linguae. It is in relation at the fraenum with its fellow of the opposite side, and in the rest of its course lies between the lower jaw and genio-hvo-glossus, being bounded be- low by the mylo- hyoid. It is in relation also with the duct of the submaxillary gland and the hypo- glossal nerve. Its secretion is poured into the mouth by from seven to twenty short ducts, ducts of Rivinus, which open on the ridge made by the gland in the floor of the mouth ; the larger openings being situated by the side of the fraenum linguae. One of the ducts longer than the rest, and opening close to Wharton’s duct, has been named ductus Bartholini. Structure.—The salivary glands are of the racemose kind, con- sisting of lobes which are made up of polyhedral lobules ; and these of smaller lobules; in minute structure they correspond with the racemose glands described on p. 62. Two kinds of alveoli are, however, to be distinguished, namely, those secreting a thick, ropy fluid containing mucin, and hence called mucous alveoli; .and those secreting a more watery fluid often con- taining serum-albumin, and named serous alveoli. The parotid is composed of serous alveoli, the sublingual of mucous alveoli, but the submaxillary is mixed in character, containing both kinds. The mucous alveoli are distinguished by possessing two sets of cells, namely, large, clear, almost spheroidal mucigenous cells, with a flat nucleus near the basement membrane ; and densely clustered smaller cells with oval nuclei, lying near the periphery of the alveolus Fic. 414.—Section of part of the human submaxillary gland. To the right of the figure is a group of mucous alveoli, to the left a group of serous alveoli ; in the former the mar- ginal cells are seen, forming the lunula of Gianuzzi. DUCTS OB' THE SALIVARY GLANDS. 709 and flattened by pressure between the basement membrane and mucigenous cells ; these are called marginal cells (lunula of Gianuzzi). In serous alveoli the gland cells almost completely fill the alveolus, and when the gland is at rest they are packed with distinct granules which obscure the nucleus ; during secretion the granules decrease in number and are limited to the periphery of the cell, so that the nucleus becomes distinct. The ducts of the salivary glands consist of a strong fibrous outer coat, beneath which are longitudinal and circular elastic layers, mixed with a few fibres of unstriped muscle ; the lining membrane is formed by a basement membrane supporting colum- nar epithelial cells. The epithelium is remarkable for its vertical striation at the part resting on the basement membrane, probably due to the presence of rod-like bodies in the protoplasm. Vessels and Nerves.—The parotid gland is abundantly supplied with arteries by the external carotid ; the submaxillary by the facial and lingual; and the sublingual by the sublingual and submental branches of the lingual artery. The capillaries form a network around and in contact with the glandular vesicles. The nerves of the parotid gland are derived from the auriculo- temporal branch of the inferior maxillary, from the auricularis magnus, and from the nervi molles accompanying the external carotid artery. In some animals the parotid also receives filaments from the glosso-pharyngeal nerve, through the lesser petrosal nerve and otic ganglion, but this distribution has not been proved to obtain in the human subject. The submaxillary gland is supplied by the branches of the submaxillary ganglion, chorda tympani, sympa- thetic, lingual branch of the fifth, and sometimes filaments from the mylo-hyoid nerve; and the sublingual by filaments from the sub- maxillary ganglion and lingual branch of the fifth nerve. Each salivary gland has three nerves distributed to it : (i) secretory filaments ending in the gland epithelium; (2) afferent branches, passing from the mucous surface on which the gland duct opens to the salivary centre ; and (3) vaso-dilator twigs to the blood-vessels supplying the gland. Fjg. 415.—Striated epithelial cell from the duct of a sali- vary gland (semi- diagrammatic). gr. Granular proto- plasm. str. Stria;. n. Nucleus. (E. A. Schcifer). TEETH. Man is provided with two sets of teeth, which appear the one in succession to the other ; the first are the teeth of childhood—they are called temporary, deciduous, or milk-teeth ; the second continue until old age, and are named permanent. The permanent teeth are thirty-two in number, sixteen in each jaw ; they are divisible into four classes : incisors, of which there are four in each jaw, two central and two lateral; canine, two above and two below ; bicuspid or premolar, four above and four below ; and molars, six above and six below. 710 TEETH. The temporary teeth are twenty in number : eight incisors, four canines, and eight molars. There are no bicuspids in the temporary set, but the eight deciduous molars are succeeded by the permanent bicuspids. The following table shows the position of the teeth relative to each other, in each set, and the relation of those of the temporary to those of the permanent series :— Temporary ( teetli. " Mo. On. In. Ca. Mo. \ Upper 2 i 4 i 2 = io [ Lower 2 1 4 1 2 =io_“° Permanent teeth. Mo. I’m. Ca. In. Ca. Pm. Mo. (Upper 3 2 1 4 1 2 3=16 l Lower 3 2 Y 4 r 2 3 = i6_j- Every tooth is divisible into a crown, which is the part above the gum ; a constricted portion around the base of the crown, the neck ; and a root or fang, which is contained within the alveolus. The root is invested bv neriosteuni. which is a bond of connection between it and the alveolus. Characters of the Permanent Teeth.—The incisors (cutting teeth) are named from presenting a sharp and cutting edge, formed at the expense of the posterior surface. The crown is flattened from before backwards, being somewhat convex in front and concave behind ; the neck is much constricted, and the root compressed from side to side ; at its apex is a small opening for the passage of the nerve and artery of the tooth. The upper incisors are directed a little forwards ; they are larger than the lower, and slightly over- lap them. The upper central incisors are much larger than the laterals ; their inner border is a little longer than their outer, and by this character we can distinguish the side to which a particular specimen be- longs. In the lower jaw the central incisors are smaller than the lateral, and have their fangs much flattened from side to side. The fangs of the lateral incisors are also flattened, but are longer than those of the central teeth. The canine teeth (cuspidati) follow the incisors in order from before backwards; two are situated in the upper jaw, one at each side, and two in the lower. The crown is larger than that of the in- Fig. 416.—Front and side view of a left upper central incisor, a. Crown, b. Neck. c. Fang. Fig. 417.—Lingual, labial, and distal surfaces of an upper canine. cieors, convex before, concave behind, and tapering to a blunted point or cusp. The root is longer than that of all the other teeth, compressed at each side, and marked by a slight groove. The upper canine teeth (called eye-teeth) are longer and larger than the lower, and are situated a little behind and external to them. The bicuspid or premolar teeth, two at each side in each jaw, follow the canine, and are intermediate in size between them and the molars. The crown is compressed from before back- wards, and surmounted by two tubercles, one internal, the other external, the latter being the largest. The neck is oval; the root is compressed, marked on each side by a deep groove, and bifid near its apex. The teeth of the upper jaw have a greater tendency to the division of their roots than those of the lower, and the posterior than the anterior pair. The lower bicuspids are smaller than the upper ; their outer cusp is long and prominent, and is bent inwards ; the inner cusp is smaller, and is connected with the outer by a slight ridge. The molar teeth (grinders), three at each side in each jaw, are the largest of the permanent set. The first molar is the largest and PREMOLAR AND MOLAR TEETH. 711 Fig. 418.— Grinding surface of an upper bicuspid. Fig. 419.—Masti- eating surface of a first upper molar of the left side. Fig. 420.—Masticating surface and side view of first lower molar of right side. The small figures indicate the five cusps. Fig. 421.—Masticating surface and side view of second lower molar of right side, The small figures indicate the four cusps. broadest, and tlie third is the smallest, so that there is a gradation of size of these teeth. The crown is quadrilateral, and is surmounted by four or five tubercles (four in the upper, five in the lower molars); the neck is large and round, and the root divided into several fangs. In the upper jaw the first and second molar teeth have three roots (sometimes four), more or less widely separated from each other, two of the roots being external, the other internal. In the lower there are but two roots, anterior and posterior, flattened from behind forwards, and grooved so as to mark a tendency to division. The first lower molar has five cusps (Fig. 420), three outer and two inner, the fifth cusp being postero-external; its anterior fang has two pulp cavities. The third molars, or wisdom- teeth (dentes sapientise), are smaller than the other two ; they present three tubercles on the surface of the crown, and the root is single and grooved, appearing to be made up of four or five fangs com- pressed together, or partially divided. In the lower jaw the fangs 712 TEETH. are frequently separated to some distance from each other, and curved backwards so as to offer considerable resistance in the operation of extraction. The range of teeth in each jaw forms a pretty uniform curve, with- out any break or diastema, such as occurs to some extent in the Quadrumana, and more markedly in the Rodents and Ruminants. Characters of the Temporary Teeth.—In general form these resemble the teeth of the permanent set, but they are smaller. The enamel which covers the crown terminates in a more distinct edge than in the permanent teeth, so that the neck is more evidently constricted. The canines are relatively shorter, and their crowns broader than those which succeed them. The second molar is the largest, being, indeed, larger than the second permanent bicuspid which succeeds it. The first upper molar has only three cusps, the second has four ; the first lower molar has four and the second five cusps. The fangs are like those of the permanent set, but are smaller and more divergent. Structure of the Teeth. If a vertical section be made through a tooth, it will be found to be hollowed out in its interior into a small cavity, the pulp cavity, which has a general resemblance in its form to the external configuration of the tooth. It extends upwards a little into the cusps, and is prolonged downwards into the fangs, terminating at the extremity of each of the latter in a small opening which trans- mits the vessels and nerves. This cavity is filled with a soft, highly vascular, and sen- sitive substance, called the dental pulp, which is continuous through the apertures at the extremity of the fangs with the periosteum on the outside of the tooth. The solid portion of the tooth is com- posed of three distinct structures :—(i) The dentine or ivory, which forms the bulk of the tooth ; (2) the enamel, which forms a lliick covering to the crown; and (3) the cement, which covers the fang externally. The dentine (ivory or tooth bone) is a hard substance having some resemblance to bone, but on microscopic examination it appears to consist of very minute, taper- ing, and branching tubules, embedded in a dense, homogeneous intertubular matrix. These tubules commence by their larger ends in the wall of the pulp cavity, and pursue a radiating and serpentine course towards the periphery of the tooth ; they give Fig. 422.—Vertical section of molar tooth, a. Enamel, b, e- come slightly atro- phied ; those which lie on its cupped or concave surface become greatly enlongated, and their nuclei recede to their bases; the central cells become chiefly converted into a stellate reticulum, the processes of the cells communi- cating freely with each other, but those which lie in contact with the columnar cells next the dental papilla remain unchanged and form a Pic,. 427.—Three stapes in the development of a mammalian tooth germ. a. Oral epithelium heaped up over germ. b. Younger epithelial cells, c. Deep layer of colls, d. In- flection of epithelium for enamel germ. e. Stellate reti- culum. /. Dentine germ. g. Inner portion of future tooth sac. li. Outer portion of future tooth sac. i. Ves- sels cut across, k. Bone of jaw. DEVELOPMENT OF DENTINE. 717 stratum intermedium. During these changes, and for long after, the epithelium constituting the enamel organ remains connected with that on the surface of the jaw by a narrow process or neck. The dentinal papillce are first observed as slightly opaque spots at some little distance from the surface and at points corresponding to the flask-like expansions above described ; they are almost as early in making tlieir appearance as the latter, but are at first much slower in development, so that the enamel organ is for some time very large in proportion to the dentinal papilla. Not only does the dentinal papilla grow upwards into the cupped cavity formed by the lower part of the enamel germ, but it also gives off lateral processes which pass to the sides of that organ, and by a continuous upward growth come later to enclose it and form the dental sac. At first the dentinal papilla only differs from the rest of the substance of the jaw in being more vascular and containing more cells, but it soon assumes the form of the future tooth, becoming simply conical for a canine, having two cusps for a bicuspid, and four or five for a molar. The cells on the surface of it become distinguished from the rest by their columnar form and close aggregation, so that they forma compact layer, which, from the part it plays in the formation of the dentine, has been named the membrana eboris, the individual cells being called odontoblasts. These cells are furnished with processes by means of which they communi- cate with each other, or with the cells deeper in the pulp ; some of the pro- cesses also pass into the dentine when it is formed, and become continuous with the protoplasm con- tained in the dentinal tubules. The enamel germ for the permanent tooth is produced by an outgrowth of epithelial cells from the side of the neck of the enamel organ of the tem- porary tooth ; this passes to the back and inner side of the latter, and undergoes the same changes in shape and composi- tion as have been described above to take place in the germ of the Fig. 428.—Dental sac of a tolerably mature human foetus, partly diagrammatic, ah Outer layer, and a2 deeper layer of fibrous wall of sac. b, b. Stel- late reticulum of enamel organ, c, c. Outer cells, and d, d, inner cells of enamel organ, f. Dental papilla with its capillaries, g. i, i. Continuation of connective tissue of the pavietes of the sac into the dental papilla. 718 TEETH. temporary tooth. The dentinal papilla also of the permanent tooth grows up beneath its enamel germ, and, assuming the characteristic shape of the tooth to be formed, has its superficial cells elongated and aggregated so as to form a membrana eboris, exactly in the same way as we have traced it in the case of the temporary tooth. The germ of the first permanent molar is formed about the sixteenth week by a down-growth of the epithelium from the surface of the jaw, in the same way as the germ for the temporary teeth originated ; the second permanent molar has its germ formed from the neck of the enamel organ of the first molar about the third month after birth. The germ for the wisdom-tooth is formed from the neck of the enamel germ of the second permanent molar about the third year. Formation of the Hard Tissues. Enamel.—We have seen that the deeper cells of the enamel organ (those, namely, which are next to the dentinal papilla) become elongated ; they also, by their mutual pressure, come to assume the form of elongated hexagonal prisms, and receive the distinctive title of enamel cells. A deposition of calcareous salts takes place in these cells, commencing at the end nearest to the papilla, and proceeding towards the centre of the enamel organ. As the process advances, the cells of the stratum intermedium assume the same form as the deeper cells, and in process of time become also calcified ; the stellate reticulum which forms the great part of the enamel organ seems to take no active part in the formation of the enamel, but, as the latter is formed, becomes progressively reduced in quantity until at length the outer or superficial cells (still epithelial in character, and become flattened) are in contact with the enamel cells. As the latter are hexagonal in form (from mutual compression), the fibres which re- sult from their calcification are necessarily hexagonal prisms. The outer part of the cell is first calcified, t he centre later, so that the outer part of the prismatic fibre is the hardest; and when fracture of the enamel takes place it usually follows the line of the centre of the fibre, this being less perfectly calcified than the periphery. Dentine.—The cells which form a com- pact layer on the surface of the dentinal papilla, and are called odontoblasts, become calcified in the same manner as the enamel cells. The calcareous deposit takes place first at the surface nearest to the enamel and passes inwards along the elongated cell ; while the outer part of the cell is thus converted into dentine, the inner end con- tinues to grow towards the papilla, and thus each dentinal tubule and its surrounding matrix is formed by the calci- fication of asingle cell,and not,as was formerly supposed, bythe union Fio. 429.—Odontoblasts in situ. ERUPTION OF TEETH. 719 of several. Most observers agree in stating that the dentinal matrix, dentinal sheaths, and the fibres contained in the tubules, represent three stages of calcification, the matrix exhibiting the completion of the process, the sheaths of Neumann an imperfect calcification, and the fibres being the unchanged protoplasm of the original cell. Klein is, however, of opinion that the fibres contained in the tubules are derived from the processes of the deeper layers of cells, and are not the product of the odontoblasts. The part of the dentinal papilla which is not converted into dentine, remains throughout life as the pulp of the tooth. Cement.—This is produced by the tissue of the tooth sac, the process being precisely the same as the production of bone beneath periosteum, described on a previous page. When the crown of the tooth has been formed and coated with enamel, and the fang has grown to the bottom of its socket by the progressive lengthening of the pulp, the formation of the dentine, and the adhesion of the latter to the contiguous portion of the sac, the pressure of the socket causes the reflected part of the sac and the edge of the tooth to approach,and thelatterto pass through the gum. The opened sac now begins to shorten more rapidly than the fang lengthens, and the tooth is quickly drawn upwards by the contrac- tion, leaving a space between the extremity of the unfinished root and the bottom of the socket, in which the growth and completion of the fang are effected. During the changes above described as tak- ing place among the dental sacs contained within the jaws, the septa between the sacs, at first consisting of spongy tissue, gradually become fibrous, and sub- sequently osseous, the bone being developed from the surface and proceeding by degrees more deeply into the jaws to constitute the alveoli. The necks of the sacs of the per- manent teeth, by which they originally communicated with the mucous surface of the gum, still exist, in the form of cords, separated from the deciduous teeth Eruption of Teeth. Fig. 430.—Normal well-formed jaws from which the alveolar plate has been removed, so as to expose the developing permanent teeth in their crypts in the jaws. 720 PHARYNX. by their alveolus, but communicating through minute osseous canals with the mucous membrane of the mouth immediately behind the corresponding deciduous teeth. The periods of appearance of the teeth are very irregular; it is necessary, therefore, to have recourse to an average, which may be stated in a tabular form as follows, the teeth of the lower jaw pre- ceding those of the upper by a short interval. SUCCESSION OF TEETH. i. Temporary Teeth. j Molar 2 Molar 1 Canine Incisors Canine Molar 1 \ Molar 2 Months. 24 12 18 9.7.7.9 18 12 24 2. Permanent Teeth. Years. 1 to Molar 3 M Molar 2 * Molar i 1 o Premclar 2 vO Premolar 1 7 Canine 00 Incisors bo 7 Canine i » o Premolar 1 M j o Premolar 2 ! Molar 1 M ! ” Molar 2 1 *** H j "f Molar 3 PHARYNX. The pharynx ( cum, is retained in position in the abdo- men either by the peri- toneum passing simply in front of it or by a narrow meso-colon. It is in relation in front with the small intes- tine and abdominal parietes ; behind with the quadratus lurnbo- rum muscle and right kidney; internally with the small intestine and descending portion of the duodenum ; and by its upper extremity with the under surface of the liver and gall- bladder (hepatic flexure). The transverse colon, the longest portion of the large intestine, forms a curve across the cavity of the abdomen, the convexity of the curve looking forwards and sometimes downwards. It is in relation, by its upper surface, with the liver, gall-bladder, stomach, and lower extremity of the spleen ; by its lower surface, with the small intes- tine ; by its anterior surface, with the anterior layers of the great omentum and abdominal parietes ; and, by its posterior surface, with the transverse meso-colon which connects it with the pancreas and duodenum. As it bends downwards to become descending colon it lies in contact with the lower end of the spleen (splenic flexure), and is connected with the inner surface of the ribs and diaphragm by a peritoneal band (phreno-colic ligament). The transverse colon is the most movable part of the large intestine. The descending colon is smaller in calibre, and situated more deeply than the ascending colon. It is generally covered by peri- toneum only in front, but in fully a third of the specimens examined there will "be found a complete envelopment by peritoneum and consequent descending meso-colon. It is in relation in front with the LARGE INTESTINE. Fig. 449.—Caecum and ileo-cmcal valve. 1. Ascending colon. 2. Csecum. 3. Ilium. 4. Vermiform appendix. 5. Ilio-colic fold. 6. Ilio-ca;cal fold. 7. Frsenula. RECTUM. 737 small intestines and great omentum, and behind with the quadratus lumborum, left kidney and left crus of the diaphragm. The sigmoid flexure, the narrowest part of the colon, curves upwards and to the right, then downwards and to the left, and is retained in its place by a sigmoid meso-colon. It is in relation, in front, with the small intestine and abdominal parietes; and behind with the iliac fossa. Including the upper part of the rectum as far as the third sacral vertebra, it has been described by F. Treves as forming a large loop somewhat resembling the Greek letter Q, and he proposes the substitution of the title Omega loop for sigmoid flexure. The rectum, the termination of the large intestine, seven or eight inches in length, has received its name, not so much from the direc- tion of its course, as from the straightness of its form in comparison with the colon. It descends from opposite the left sacro-iliac sym- physis, in front of the sacrum, forming a gentle curve to the right side, and then returning to the middle line ; opposite the extremity of the coccyx it curves backwards to terminate in the anus at about an inch in front of the apex of that bone. The rectum, therefore, forms a double flexure in its course, the one being directed from side to side, the other from before backwards. It is smaller in calibre at its upper part than the sigmoid flexure, but becomes gradually larger as it descends, and its lower extremity, previously to its termina- tion at the anus, forms a dilatation of considerable but variable magnitude. It is not sacculated like the colon, and has no separate longitudinal bands on it. With reference to its relations, the rectum is divided into three portions ; the first, including half its length, extends to about the middle of the sacrum, is completely surrounded by peritoneum, and connected to the sacrum by means of the meso-rectum. This por- tion is in relation above with the left sacro-iliac symphysis ; and below, with the branches of the internal iliac artery, sacral plexus of nerves and left ureter; one or two convolutions of the small intestine are interposed between the front of the rectum and the bladder in the male ; and between the rectum and the uterus with its appendages in the female. The second portion, about three inches in length, is closely attached to the surface of the sacrum, and is at first covered by peritoneum on the front and sides, but lower down has that membrane only in front; it is in relation by its lower part with the base of the bladder, vesiculse seminales, and prostate gland ; and in the female with the vagina. The third portion curves backwards from opposite the prostate gland and tip of the coccyx to terminate in the anus ; it is embraced by the levatores ani, and is about one inch and a half in length. It has no peritoneal covering, and is separated by the recto-vesical fascia from the prostate gland, vasa deferentia, vesiculoe seminales and trigone of the bladder. This portion is separated from the mem- branous part of the urethra by a triangular space ; in the female the triangular space intervenes between the vagina and rectum, and constitutes by its base the perineal body. Immediately above its 738 LARGE INTESTINE. termination the rectum undergoes considerable enlargement, and bulges forwards, so as to give the anus the appearance of being bent backwards ; this dilatation is called the sinus analis. The anus is situated at a little more than an inch in front of the extremity of the coccyx. The integument around it is covered with hairs, and is thrown into numerous radiated folds, which are obliterated during the passage of faeces, 'l he anal passage or canal is described by Symington as connecting the anal aperture with the rectum ; it is from half an inch to an inch in length, and when closed has its lateral walls in contact with each other, so that the lumen has the form of a median slit. The margin of the anus is provided with an abundance of sebaceous glands, and the epidermis may be seen terminating by a fringed and scalloped border, at a few lines above the extremity of the opening. Structure of the Large Intestine. The large bowel has the same coats as the small, namely, serous, muscular, submucous and mucous. SEROUS COAT.—The peritoneum forms the serous coat; its arrangement in relation to the several parts of the colon has been described on a previous page (p. 702). MUSCULAR COAT.—'ibis consists, as in the small intestine, of longitudinal and circular fibres. The longitudinal fibres commence at the appendix vermiformis, and are collected into three bands— anterior, broad ; and two narrower bands, one placed posteriorly and the other laterally. The anterior band corresponds in the transverse colon to the line of attachment of the great omentum ; the posterior band is at the attached border of the colon ; and the lateral one lies on the inner aspect of the ascending and descending colon, and under surface of the transverse colon. These bands, the ligamenta coli, are nearly one-half shorter than the intestine, and serve to maintain the sacculated structure of the caecum and colon. In the descending colon the posterior bands usually unite and form a single band. In addition to these bands, the longitudinal fibres are also sparsely distributed over the surface of the sacculi. In the lower part of the sigmoid flexure, the muscular fibres of the longitudinal bands begin to spread out, and in the rectum the fibres are regularly distributed throughout the entire calibre of the bowel. The circular fibres are distributed over the whole surface of the colon, but are thickest in the sulci between the sacculi. In the caecum and colon they are very thin ; in the rectum they are thicker, and near its lower extremity are aggregated into the thick muscular band which is known as the internal sphincter ani. SUBMUCOUS COAT.—This coat in all respects corresponds to that in the small intestine. MUCOUS COAT.—In the caecum and colon the mucous membrane is smooth, and lines the surfaces of the folds which form the boundaries ILIO-CiECAL VALVE. 739 of the sacculi of the large intestine. In the rectum it forms three valvular folds (valves of Houston), one of which is situated near the commencement of that part of the intestine ; the second, extend- ing from the side of the tube, is placed opposite the middle of the sacrum ; and the third, which is the largest and most constant, pro- jects from the anterior wall of the bowel opposite the prostate gland. Besides these folds, the membrane in the empty state of the intestine is thrown into longitudinal pleats somewhat similar to those of the oesophagus; these have been named the columns of the rectum (icoltimnce recti of Morgagni). The mucous membrane of the rectum is connected to the muscular coat by a loose areolar tissue, as in the oesophagus. One character serves infallibly to distinguish the mucous mem- brane of the small intestine from that of the large, namely, that the former is studded over throughout by minute conical processes called villi, which are entirely absent from the latter. The mucous membrane of the large intestine is furnished with Lieberkiihn’s follicles, resembling those of the small intestine ; they are, however, more numerous, are much longer, and contain a larger number of mucous-cells. The lymphoid tissue of the large bowel forms spherical masses, like those described in the structure of the small bowel under the name of solitary glands, but they are smaller and less prominent. They are especially numerous in the caecum and vermiform appendix. The epithelium on the surface of the large intestine is columnar, and the mucous membrane has on its deep aspect a definite muscularis mucosae. Ilio-csecal Valve.—At the termination of the ileum in the large intestine, the mucous membrane forms two semilunar folds, strengthened by the muscular coat. The termination of the ileum is oblique and flattened, and constitutes the division between the caecum and colon, the two folds of mucous membrane being the ileo- ccecal or ileo-colic valve (valve of Bauhin or valve of Tulpius). The position of these folds is such that one belongs to the caecum, the other to the colon, the opening between them being oblong and oval, and not inaptly compared to a button-hole ; moreover, the colic flap somewhat overlaps the caecal flap, and is so disposed in relation to the entrance of the ileum that the contents of the small bowel are necessarily discharged into the caecum. The upper or ileo-colic fold is horizontal in its direction, the lower or ileo-caecal is nearly ver- tical ; both folds are prolonged on each side for some distance beyond the ends of the opening, these prolongations being called frenula or retinacula. The opening from the ileum to the caecum is rounded and wide at its anterior and left end, narrow and pointed at the posterior. The description of the vessels and nerves distributed to the alimentary canal has been given with the anatomy of the small intestine. 740 LIVER THE LIVEI1. The liver is the largest gland in the body, weighing about four pounds, and measuring through its longest diameter about twelve inches ; its breadth is commonly about six to seven inches, and its greatest thickness three and a half inches. It is situated in the right hypochondriac region, and extends across the epigastrium into the left hypochondriiun, frequently reaching, by its left ex- tremity, the upper end of the spleen. It is placed obliquely in the abdomen ; its convex surface looking upwards and forwards, the concave downwards and backwards. The anterior border is sharp and free, and marked by a deep notch, and the posterior rounded and broad. His has pointed out that the liver when in the body has three surfaces, and not two, as usually described. The additional Fio. 450.—Upper surface of the liver. 1. Right lobe. 2. Left lobe. 3. Anterior or free border. 4. Posterior or rounded border. 5. Falciform ligament. 6. Round liga- ment. 7, 7. The two lateral ligaments. 8. The space left uncovered by the perito- neum, and surrounded by the coronary ligament. 9. Inferior vena cava. 10. Fomt of the lobus Spigelii. 3. Fundus of the gall-bladder seen projecting beyond the anterior border of the right lobe. surface looks altogether backwards, and may hence he named the posterior surface ; it includes the posterior border, the whole of the Spigelian lobe, and a strip of the left lobe. The liver is in relation, superiorly and posteriorly, with the diaphragm ; interiorly with the stomach, ascending portion of the duodenum, transverse colon, right supra-renal body, and right kidney ; and corresponds, by its free border, with the lower margin of the ribs. Ligaments.—The liver is retained in its place by five ligaments, four of which are duplieatures of the peritoneum, situated on the convex surface of the organ ; the fifth is a fibrous cord which passes through a fossa in its under surface, from the umbilicus to the inferior vena cava. They are the— Falciform, Coronary, Two lateral, Round. LIGAMENTS OF THE LIVER. The falciform ligament (broad or suspensory) is an antero- posterior fold of peritoneum, extending from the notch in the anterior margin of the liver to its posterior border. Between its two layers, in the anterior and free margin, is the round ligament. It divides the upper surface of the liver into the right and left lobes. The coronary ligament is formed by the separation of the two layers of peritoneum which pass from the diaphragm to the liver. The posterior layer is continued unbroken from one lateral ligament to the other ; but the anterior quits the posterior at each side, and is continuous with the corresponding layer of the falciform liga- ment. In this way a large oval surface on the posterior border of the liver is left uncovered by peritoneum, and is connected to the diaphragm by areolar tissue. I his space is formed principally by the right lateral ligament, and is pierced near its left extremity by the inferior vena cava, previously to the passage of that vessel through the tendinous opening in the diaphragm. The lateral ligaments are formed by the two layers of perito- neum which pass from the under surface of the diaphragm to the posterior border of the liver ; they are lateral extensions of the coronary ligament. The round ligament is a fibrous cord resulting from the oblite- ration of the umbilical vein, and situated between the two layers of peritoneum in the anterior border of the falciform ligament. It may be traced from the umbilicus through the longitudinal fossa of the under surface of the liver to the inferior vena cava, with which it is connected. Fissures.—The under surface of the liver is marked by five fissures, which divide its surface into five compartments or lobes, two principal and three minor lobes ; they are the— Fissures. Longitudinal fissure, Fissure for the ductus venosus, Transverse fissure, Fissure for the gall-bladder, Fissure for the vena cava. Lobes. Right lobe, Left lobe, Lobus quadratus, Lobus Spigelii, Lobus caudatus. The longitudinal fissure is a deep groove running from the notch, umbilical fissure, in the anterior margin of the liver, to the posterior border of the organ. At about one-third from its posterior extremity it is joined by a short but deep fissure, the transverse, which meets it transversely from the under part of the right lobe. In front of this junction it lodges the fibrous cord of the umbilical vein, and is generally crossed by a band of hepatic substance called the pons hepatis. The fissure for the ductus venosus is the shorter portion of the longitudinal fissure, extending from the junctional termination of the transverse fissure to the posterior border of the liver, and con- 742 LIVER, taining a small fibrous cord, the remains of the ductus venosus. This fissure is therefore but a part of the longitudinal fissure. The transverse or portal fissure is the short and deep fissure, about two inches in length, through which the hepatic ducts quit and the hepatic artery and portal vein enter the liver. Hence this fissure was considered by the older anatomists as the gate of the liver, porta liepatis; and the large vein entering the organ at this point, was named the portal vein. At their entrance into the trans- verse fissure the branches of the hepatic duct are the most anterior, next those of the artery, and most posteriorly the portal vein. Be- sides these three structures, the nerves and lymphatics also enter the liver through this fissure. The fissure for the gall-bladder is a shallow depression extend- ing forwards, parallel with the longitudinal fissure, from the right extremity of the transverse fissure to the free border of the liver, where it frequently forms a notch, incisura vesicalis. The fissure for the vena cava is a deep and short fissure, occa- sionally a circular tunnel, which proceeds from a little behind the right extremity of the transverse fissure to the posterior border of the liver, and lodges the inferior vena cava. It lies between the Spigelian lobe and the right lobe, and has opening into it the hepa- tic veins, by which the blood leaves the liver. The relative position of these fissures, and the lobes which they limit, will be best understood from the subjoined scheme, for which we are indebted to Prof. D. J. Cunningham :— Posterior border Longitudinal fissure Spigelian lobe Transverse fissure Left lobe Fissure for gall-bladder Right lobe (Quadrate lobe Anterior border Lobes.—The right lobe is four or six times larger than the left, from which it is separated, on the concave surface, by the longi- tudinal fissure, and on the convex, by the falciform ligament. It is marked on its under surface by the transverse fissure, and by the fissures for the gall-bladder and vena cava; and presents three depressions, one in front (impressio colica) for the curve of the ascending colon, and one behind (impressio renalis) for the right supra-renal capsule and kidney. On the inner edge of the renal impression, a narrow and indistinct marking is generally present, being the part against which the ascending duodenum lies (impressio duodenalis). The left lobe is small and flattened, convex on its upper surface and concave below, where it lies in contact with the anterior sur- face of the stomach. It is sometimes in contact by its extremity LOBES OF THE LIVER. 743 Fig. 451.—Under surface of the liver. 1. Right lobe. 2. Left lobe. 3. Lobus quadratus. 4. Lobus Spigelii. 5. Lo- bus caudatus. 6. Lon- gitudinal fissure ; the figure is placed on the rounded cord, the re- mains of the umbili- cal vein. 7. Pons he- patis. 8. Fissure of the ductus venosus; the obliterated cord of the ductus is seen passing backwards to be at- tached to the coats of the inferior vena cava (9). 10. Gall - bladder lodged in its fissure. 11. Transverse fissure, containing, from before backwards, hepatic duct, hepatic artery, and portal vein. 12. Vena cava. 13. Depression corresponding with the curve of the colon. 14. Depression produced by the right kidney. 15. Rough surface on the posterior border of the liver left uncovered by peritoneum; the cut edge of the peritoneum surrounding this surface forms part of the coronary ligament. 16. Notch on the anterior border separating the two lobes. 17. Notch on the posterior border corresponding with the vertebral column. witli the upper end of the spleen, and is in relation, by its posterior border, with the cardiac orifice of the stomach and left pneumo- gastric nerve. The lobus quadratus is a quadrilateral lobe situated on the under surface of the right lobe : it is bounded, in front, by the free border of the liver ; behind, by the transverse fissure ; to the right, by the gall-bladder ; and to the left, by the longitudinal fissure. The lobus Spigelii is a small triangular lobe, also situated on the under surface of the right lobe : it is bounded, in front, by the transverse fissure ; and, on the sides, by the fissures for the ductus venosus and vena cava. The lobus caudatus is a small tail-like appendage of the lobus Spigelii, from which it runs outwards like a crest into the right lobe, and serves to separate the right extremity of the transverse fissure 744 L1VEK. from the commencement of the fissure for the vena cava. In some persons this lobe is well marked, in others it is small and ill-defined. Position of the Liver in relation to the Abdominal and Thoracic Wall.—The upper convex surface reaches as high as the level of the fifth right chondro-sternal articulation; the lower border corresponds pretty accurately to the inferior margin of the cartilages of the 6tli, 7th, 8th, and 9th ribs on the right side. The left lobe extends to about an inch to the left of the middle line, and lies against the anterior wall of the abdomen, its lower border being indicated bv a line drawn from the ninth right to the eighth left costal cartilage. The gall-bladder has its fundus at the outer border of the rectus muscle, under the ninth right costal cartilage. Vessels and Nerves.—The vessels entering into the structure of the liver are also ./ire in number ; they are the— Hepatic artery, Portal vein, Hepatic veins, Hepatic ducts, Lymphatics. The hepatic artery, portal vein, and hepatic duct enter the liver together at the transverse fissure, and ramify through portal canals to every part of the organ ; so that their general direction is from below upwards, and from the centre towards the circumference. The hepatic veins commence at the circumference, and proceed from before backwards, to open into the vena cava at the posterior border of the liver. The portal vein, hepatic artery, and hepatic duct are enveloped in a loose areolar tissue, the capsule of Glisson, which permits them to contract upon themselves when emptied of their contents ; the hepatic veins, on the contrary, are closely adherent by their walls to the substance gf the liver in which they run, and are unable to contract. The former will consequently be found in any section more or less collapsed, and always accompanied by an artery and duct, and the latter widely open and solitary. The lymphatics of the liver are described in the section dedicated to those vessels. The nerves of the liver are derived from the spinal and sympa- thetic system ; the former proceed from the right phrenic and right pneumogastric nerve, the latter from the hepatic plexus. The li vex* is composed of lobules, of areolar tissue which connects them together, of the ramifications of the portal vein, hepatic duct, hepatic artery, hepatic veins, lymphatics, and nerves, and is enclosed and retained in its situation by the peritoneum. The serous coat, formed by the peritoneum, covers the whole surface of the liver, excepting a triangular area situated near the posterior border of the organ, at the meeting of the coronary and falciform ligaments. This coat is inseparable from the fibrous coat, or Glisson’s capsule. The lobules are small granular bodies which vary in size from Minute Anatomy of the Liver. MINUTE STRUCTURE OF THE LIVER. 745 ■A th to -jVth of an inch. When divided longitudinally, they have a foliated appearance, and transversely, a polygonal outline, with sharp or rounded angles, according to the smaller or greater quantity of areolar tissue contained in the liver. Each lobule is divided on its exterior into a base and a peripheral surface. The base corresponds with one extre- mity of the lobule, is flattened, and rests on an hepatic vein, which is thence named sublobular. The peri- pheral surface includes the rest of the surface of the lobule. In the centre of each lobule is a small vein, the intralobular, which is formed by the convergence of six or eight minute venules from the lobule. The intra- lobular vein thus constituted takes its course through the centre of the longitudinal axis of the lobule, pierces the middle of its base, and opens into the sublobular vein. The periphery of the lobule, with the exception of its base, which is always closely attached to a sublobular vein, is connected by means of its areolar tissue, with Fig. 452.—Lobules of the liver. The lobules as they are seen on the sur- face of the liver, or when divided transversely. 1. Intralobular vein in the centre of each lobule. 2. In- terlobular fissure. 3. Interlobular space. Fig. 453.—Longitudinal section of two lobules. 1. A superficial lobule, terminating abruptly, and re- sembling a section at its extremity. 2. A deep lobule, showing the foliated appearance of its section. 3. Intralobular vein, with its converging venules; the vein terminates in a sublobular vein. 4. External surface of the lobule. the surfaces of surrounding lobules. The interval between the lobules is the interlobular fissure, and the angular interstices formed by the apposition of several lobules are the interlobular spaces. In ultimate structure the lobule is composed of hepatic cells, of a vascular plexus which receives its blood exteriorly from an’ interlobular branch of the portal vein and transmits it internally to the intralobular vein, the radicle of the hepatic vein, of stromal supporting tissue, and of the ultimate ramifications of the biliary ducts. The hepatic cells are nucleolo-nucleated cells, of a polyhedral figure, measuring about 1 of an inch in diameter, and of a pale amber colour. They have no distinct cell-wall, and when isolated possess the power of amoeboid motion ; their contents are granular and often fatty vesicles of various sizes may be observed in their interior. The cells are arranged in a network corresponding with 746 LIVER. the vascular plexus, the columns or solid portions of the network constituting the secretory portion of the gland ; the vessels are not in absolute contact with the hepatic cells, hut are separated from them by a membrane formed of battened cells, the space left between this membrane and the capillary Avail forming a lymph channel. In order to understand the relations which the cells bear to the Aressels and ducts, it will be necessary to trace the tAvo latter from the transverse fissure to the interior of the 1 iver, and to note their arrangement in the portal canals, around the lobules, and in the substance of the lobules. The portal vein, hepatic artery, and hepatic duct run to- gether in the interior of the liver, being contained in channels formed by a layer of connective tissue called Glisson’s cap- sule, the channels re- ceiving the name of portal canals ; the hepatic veins run a totally independent course, and terminate in the inferior vena cava, Avliere it lies against the under and posterior part of the liver. Glisson's capsule is the areolar tissue Avliich envelops the hepatic artery, portal vein, and hepatic duct, during their passage through the transverse fissure, and Avhich continues to surround them in the interlobular fissures. It also constitutes the proper capsule of the entire organ. Hence arises a division of the capsule into tAvo portions, vaginal and investing. The \raginal portion is that which invests the hepatic artery, hepatic duct, and portal vein, in the portal canals ; in the large canals it completely surrounds these vessels, but in the smaller is situated only on that side which is occupied by the artery and duct. The investing portion is that Avhich covers the exterior of the organ. The portal vein enters the liver at the transverse fissure, and ramifies throughout its structure in the portal canals ; in the smaller canals Glisson’s capsule only envelops the artery and duct, so that the portal vein is in direct contact with the lobules. The branches of the portal vein are—A’aginal, interlobular, and lobular. The vaginal branches are those which, being given off in the portal canals, have to pass through the sheath (vagina) of Glisson’s capsule, previously to entering the interlobular spaces. In Fig. 454.—Cells of the liver. One large mass shows the shape they assume, by mutual pressure, (a) The same free, when they become spheroidal. (6) More magnified, (c) During active digestion containing refracting globules like fat. MINUTE STRUCTURE OF THE LIVER, 747 this course they form an intricate plexus, vaginal plexus, in the capsule of Glisson, and this plexus surrounds the vessels as does the capsule in the larger canals, and occupies the capsular side only in the smaller canals. The interlobular branches are given off from Fig. 455.—Section of lobule of the liver of a rabbit, in which the blood and bile capil- laries have been injected, a. Intralobular vein. 6. Interlobular veins, c. Biliary- canals beginning in fine capillaries. the vaginal portal plexus where it exists, and directly from the portal veins, in that part of the smaller canals where the coats of the vein are in contact with the walls of the canal. They then enter the interlobular spaces and divide into branches, which cover with their ramifications every part of the surface of the lobules, with the 748 LIVER. exception of their bases and those extremities of the superficial lobules which appear on the surfaces of the liver. The lobular branches are derived from the interlobular veins ; they form a plexus within each lobule, and converge from the circumference towards the centre, where they terminate in the minute radicles of the intralobular vein. This plexus, interposed between the inter- lobular portal veins and the intralobular hepatic vein, constitutes the venous part of the lobule, and is called the lobular venous plexus. The regular islets of the substance of the lobules, seen between the meshes of this plexus by means of the microscope, are the network of hepatic cells. The portal vein returns the venous blood from the chylopoietic viscera, to be circulated through the lobules ; it also receives the blood which results from the distribution of the hepatic artery. The hepatic artery enters the liver with the portal vein and hepatic duct, and ramifies with those vessels through the portal canals. Its branches are—vaginal, interlobular, and capsular. The vaginal branches, like those of the portal vein and hepatic duct, form a vaginal plexus, which exists throughout the whole extent of the portal canals, with the exception of that side of the smaller canals which corresponds with the artery. The interlobular branches, arising from the vaginal plexus and from the parietal side of the artery (in the smaller canals), ramify through the inter- lobular fissures, and are principally distributed" to the coats of the interlobular ducts. The capsular branches ramify within the capsule, accompanied by small veins. The hepatic veins commence in the substance of each lobule by minute venules, which receive the blood from the lobular venous plexus, and converge to form the intralobular vein. The intra- lobular vein passes through the central axis of the lobule, and through the middle of its base, to terminate in a sublobular vein ; and the union of the sublobular veins constitutes the hepatic trunks, which open into the inferior vena cava. The hepatic trunks are formed by the union of the sublobular veins ; they have very thin Avails and are in almost immediate contact with the lobules, even the larger veins being only separated by a small quantity of areolar tissue. They proceed from before backwards, and terminate, by two large openings (corresponding with the right and left lobe of the liver) and several smaller apertures, in the inferior vena cava. Biliary Capillaries and Ducts—The biliary capillaries begin as minute passages between the sides of contiguous bile-cells, in which no definite wall has hitherto been demonstrated. They appear to communicate by minute channels with vacuoles in the cells themselves. The bile capillaries form a fine plexus through- out the Avhole of the lobule, lobular plexus of ducts, and on leaching the circumference thereof, form a second plexus on its exterior, the interlobular plexus of ducts. From this plexus ducts are derived which run in the portal canals, being placed in each case on the same side as the hepatic artery, and surrounded MINUTE STRUCTURE OF THE LIVER. 749 by Glisson’s capsule ; they form fine plexuses in the portal canals, vaginal plexuses, and terminate by uniting to form the hepatic duct at the transverse fissure. The ducts in the interlobular plexus have definite walls formed by a basement membrane, lined by a single layer of flattened or cubical epithelial cells : the larger ducts have their mucous membrane supplied with a large number of tubular or flask-shaped mucous recesses, having much the appear- ance of mucous glands ; these are arranged in two rows, one on each side of the vessel. The largest ducts have an outer coat of areolar and elastic tissue, a middle coat of longitudinal and circular Fig. 456.—Biliary capillaries from the rabbit’s liver. 1. Part of a lobule, a. Intra- lobular vein, b, b. Interlobular vein, c, c, c. Biliary ducts, d, d, d. Lobular venous plexus, e, e, e. Biliary capillaries. 2. Biliary capillaries (h) in their relation to the capillaries of ttie vascular system (a). 3. Biliary capillaries in their relation to the hepatic cells, a. Biliary capillaries. 6. Hepatic cells, c. Biliary ducts, d. Capillaries of the blood-vessels. muscular fibres, and a mucous membrane lined with columnar epi- thelium, and possessing true, lobulated, mucous glands. The right and left hepatic ducts unite to form the common hepatic duct, and this in turn is joined by a duct from the gall- bladder, the two together forming the common bile duct (ductus communis choledochus). The common bile duct runs in the free border of the lesser omentum, being placed to the right of the hepatic artery and in front of the portal vein. It passes behind the descending portion of the duodenum to the inner side of that intestine, where it terminates by passing obliquely between the muscular and mucous coat, and opening on the summit of a papilla which is common to it and the pancreatic duct. The papilla is situated near the lower part of the descending portion of the duodenum at its inner side ; and the duct is constricted in size during its passage between the coats of the intestine. Lymphatics and Nerves.—The lymphatic vessels accompany the GALL-BLADDER. portal vein through the portal canals and into the interlobular fissures ; they originate in the spaces described above as separating the capillaries from the biliary cells. There are also superficial lymphatic plexuses beneath the peritoneum, those on the upper convex surface communicating with the lymphatics of the dia- phragm and thorax. The nerves form the hepatic plexus, and are derived from the solar plexus and the left pneumogastric and right phrenic nerves. The branches entering the liver are very small ; they run with the arteries and ducts in the portal canals, those on the former having minute ganglia in their course. Some of the branches form an interlobular plexus, which gives twigs to the surface of the hepatic cells. Foetal Liver.—The liver is one of the first formed abdominal organs in the embryo, consisting primarily of two small masses of hypo-blastic origin, which grow out from the duodenum just beyond the stomach, and penetrate the meso-blastic mass between those organs and the abdominal wall. The cells rapidly increase in number, those of hypo-blastic origin forming solid cylinders which ramify and anastomose with each other, and finally constitute the secretory portion of the gland ; the meso-blastic cells included within the network of the former constituting the areolar and vascular structure of the organ. Subsequently the solid cylinders are hollowed in their interior and form the biliary ducts. At the sixth week the liver fills the whole abdomen, and is one-half the weight of the entire embryo. At the fourth month the liver is of immense size in proportion to the bulk of the foetus. At birth it is of very large size, and occupies the whole upper part of the abdomen. The left lobe is as large as the right, and the falciform ligament corresponds with the middle line of the body. The liver diminishes rapidly after birth, probably from obliteration of the umbilical vein. GALL-BLADDER,. The gall-bladder (Fig. 457) is the reservoir of the bile ; it is a pyriform sac, situated in a fossa on the under surface of the right lobe of the liver, and extending from the right extremity of the transverse fissure to the free margin. It is divided into a body, fundus, and neck ; the fundus or broad extremity in the natural position of the liver is placed downwards, and frequently projects beyond the free margin of the liver, while the neck, small and con- stricted, is directed upwards. The fundus comes in contact with the abdominal wall opposite the ninth costal cartilage of the right side. The gall-bladder is composed of three coats, serous, fibrous, and mucous. The serous coat is partial, is derived from the peritoneum, and covers that side only which is unattached to the liver. The middle or fibrous coat is a thin but strong fibrous layer, composed of dense areolar tissue, and connected on the one side with the liver, on the other with the peritoneum. There also exists in this layer a stratum of unstriped muscular fibres, which are longitudinal and PANCREAS. circular in direction. The internal or mucous coat is but loosely attached to the fibrous layer; it is everywhere raised into minute rugee, which give it a beautifully reti- culated appearance. It is continuous through the hepatic duct with the mucous membrane lining the ducts of the liver, and through the common bile duct, with the mucous membrane of the alimentary canal. It is coated on its surface with a columnar epithelium. At the neck the gall-bladder becomes narrowed, much bent on itself, forming an S-like curve, and passes into the cystic duct; in the interior the reticular folds become modified so as to form seven or eight oblique ridges, having much the appear- ance of a spiral valve, so as to check the outflow of the bile. These folds are called valves of Heister. The cystic duct, about an inch and a half in length, runs downwards and backwards to join the hepatic duct and form the common bile duct. Vessels and Nerves.—The gall-bladder is supplied with blood by the cystic artery, a branch of the hepatic. Its veins return their blood into the portal vein. The nerves are derived from the hepatic plexus. Fig. 457.—Gall-bladder and biliary ducts, i. Gall-blad- der. 2. Cystic duct. 3. Valves of Heister. 4 Hepatic duct. 5. Common bile duct. THE PANCREAS. The pancreas is a long, flattened, conglomerate gland, analogous to the salivary glands. It is about six inches in length, and between three and four ounces in weight; is situated transversely across the posterior wall of the abdomen, behind the stomach, and rests on the aorta, portal vein, inferior vena cava, the origin of the superior mesenteric artery, and the left kidney and supra-renal body, opposite the first lumbar vertebra. After the abdominal cavity has been laid open, the pancreas may be displayed in one of three ways :— (i) By cutting through the lesser omentum and drawing the stomach downwards ; (2) by cutting through the great omentum and dis- placing the stomach upwards ; and (3) by cutting through the trans- verse meso-colon. A glance at the diagram of the reflections of peritoneum (Fig. 409) will enable the student to understand how the pancreas is reached by each of these incisions. The pancreas is divided into a body, a greater and a smaller extremity ; the great end or head is placed towards the right, and surrounded by the curve of the duodenum ; the lesser end or tail extends to the left as far as the spleen. The anterior surface of the body of the pancreas is covered by the ascending posterior layer of peritoneum, and is in relation with the stomach, the first portion of the duodenum, and the commencement of the transverse arch of the 752 PANCREAS. colon. The posterior surface is grooved for the splenic vein, and tunnelled l>y a complete canal for the superior mesenteric and portal veins, and superior mesenteric artery ; it is also in relation with the termination of the inferior mesenteric vein, left crus of the diaphragm, and left supra-renal body. The upper border presents a deep groove, sometimes a canal, for the splenic artery and vein, and is in rela- tion with the oblique portion of the duodenum, lobus Spigelii, and cotdiac axis ; and the lower border is separated from the transverse portion of the duodenum by the superior mesenteric artery and vein. On the posterior part of the head of the pancreas is a lobular fold of the gland which completes the canal of the superior mesenteric vessels, and is called the lesser pancreas. The tail lies on the left kidney, and its extremity is in contact with the spleen. The pancreatic duct (duct of Wirsung) com- mences at the small ex- tremity of the organ by the union of the ducts from the lobules; it is continued onwards from left to right, gradually increasing in size, to the lower part of the descend- ing duodenum, where it terminates on the papilla of mucous membrane, common to it and the common bile duct. The duct receives numerous branches which open into it on all side from the lobules of the gland, and at its termination is slightly dilated and passes obliquely between the muscular and mucous coat of the intestine to reach the papilla. The duct which receives the secretion from the lesser pancreas is called the ductus pancreaticus minor; it opens into the principal duct near the duodenum, and sometimes passes separately into that intestine. In structure the pancreas presents the ordinary composition of an acino-tubular gland, being made up of lobes, and these of reddish- yellow polyhedral lobules, which latter consist of smaller lobules, and the smallest lobules of the ramifications of minute ducts, ter- minating in tubular alveoli. The alveoli are distinctly tubular, and sometimes are convoluted ; the cells lining them are columnar, and when the gland is at rest they completely fill the cavity and leave scarcely any lumen. They display an inner granular and an outer striated zone. In many parts the middle of the alveolus is occupied by spindle-shaped cells (centro-acinar cells). Intercellular passages Fig. 458.—Section of the pancreas of a dog, showing the inner granular zone and outer clear, striated zone. d. Termination of a duct in the tubular alveoli, a. SPLEEN. 753 have been described as running between the gland cells. The ducts are composed of areolar and elastic tissue, and lined by a columnar epithelium. In the walls of the ducts are numerous small racemose mucous glands like those in the hepatic ducts. The secretion of the pancreas is a clear fluid containing few cells. Vessels and Nerves.—The arteries of the pancreas are branches of' the splenic, hepatic, and superior mesenteric ; the veins open into the splenic and superior mesenteric veins ; the lymphatics terminate in the lumbar glands. The nerves are filaments of the solar plexus. THE SPLEEN. The spleen is an oblong flattened organ, of a dark bluisli-red colour, situated in the left hypochondriac region. It is very variable in size and weight, but on an average is about five inches in length, and weighs six ounces; it is spongy and vascular in texture, and exceedingly friable. The external surface is convex, the internal slightly concave, indented along the middle line, and pierced by several large and irregular openings for the entrance and exit of vessels ; this is the hiium lienis. The upper extremity is somewhat larger than the lower, and rounded ; the inferior is battened ; the posterior border is obtuse, the anterior sharp, and marked by several notches. The spleen is in relation by its external or convex surface with the diaphragm, which separates it from the ninth, tenth, and eleventh ribs ; by its concave surface, with the great end of the stomach, small extremity of the pancreas, gastro-splenic omentum with its vessels, left kidney and supra-renal body, and left crus of the diaphragm ; by its upper end with the diaphragm, and some- times with the extremity of the left lobe of the liver; and, by its lower end, with the left extremity of the transverse arch of the colon. It is connected to the stomach by the gastro-splenic omentum, and is supported by a fold of peritoneum passing from the diaphragm to the splenic flexure of the colon, and called the phreno-colic ligament or suspensory ligament of the spleen. Fig. 459.—a. Trabeculae of Spleen, b. An artery cut obliquely. 754 A second spleen (lien succenturiatus) is sometimes found appended to one of the branches of the splenic artery, near the great end of the stomach ; when it exists, it is round and of small size, rarely larger than a hazel-nut. There are sometimes two, and even three, of these bodies. Structure.—The spleen is closely invested by the peritoneum, excepting where that membrane is reflected on to the stomach and diaphragm, and at the hilus where the vessels and nerves enter it; this forms its outer or serous coat. Beneath this is the proper capsule or tunica propria ; it is thicker than the serous coat, whitish in appearance, and very- elastic. At the hilus the capsuh is reflected into the interior Oi. the organ along with the vessels! forming strong bands or tra- beculae which radiate from the centre to the circumference, and communicate with each other so as to form a mesh-work enclosing irregular spaces or areolae ; the tine external strands of the tra- beculae become connected with the interior of the capsule, binding it firmly and inseparably to the internal structure of the organ. Besides fibrous and elastic tissue these bands contain a few un- striped muscular fibres irregularly distributed. The interspaces or areolae thus formed are tilled by a soft material of a reddish-brown colour, called the splenic pulp ; it consists of a fine reticulum of ramified connective-tissue corpuscles (supporting cells of the pulp), the in- terstices of which are occupied by blood, con- taining more than the usual proportion of white corpuscles. The cells of the reticulum contain many pigment granules of a yellow or reddish colour ; these are probably derived from dis- integrated red blood corpuscles, and, indeed, it is not uncommon to find corpuscles in various stages of change in the protoplasm of the sup- porting cells. Scattered throughout the spleen numerous light-coloured spots are observed, which, when of large size, present the appear- ance of sago grains ; they are the Malpighian CDrpuscles of the spleen. They are closely connected with the outer coat of the small arterial twigs, sometimes being situated only on one side of the vessel (as shown in Fig. 461), but more commonly in the human subject completely surrounding SPLEEN. Fit;. 460.—Reticulum of the splenic pulp. а. Meshes covered with endothelium. б. Lacunar spaces, c. Nuclei. Fig. 461.—Arterial twig of the splenic artery, showing the connection of thespleniccorpuscles with the small vessels. From the spleen of a dog. STRUCTURE OF THE SPLEEN. 755 it. In structure they correspond closely to the lymphoid masses described as forming the tonsils, the solitary and agminate glands of the intestine, and the lymph nodules of the lymphatic glands, being composed of retiform tissue supporting innumerable round lymphoid cells. The cells of the retiform tissue are intimately connected with the supporting cells of the pidp. The outer coat of the smaller arteries is, throughout the whole of their ramifications in the spleen, converted into lymphoid tissue, so that the Malpighian corpuscles aie but thicker aggregations of this tissue at certain parts of the course of the vessel. Arrangement of the Vessels of the Spleen.—The splenic artery is of very large size in proportion to the bulk of the spleen ; it is a division of the cceliac axis. The branches which enter the spleen are distributed to dis- tinct sections of the organ, and anastomose very sparingly with each other ; they ter- minate in elegant bundles or pencilli of minute straight ar- teries, which end in capillaries. The latter, after running for a short distance, lose their tubular char- acter, and the cells which form their walls become branched and communicate freely with the branched cells of the supporting reticulum of the pulp ; the contained blood comes thus to How directly into the interstices of the latter. The veins commence in like manner by capillaries, the cells forming the walls of which are continuous with those of the pulp ; as we trace them outwards they assume the tubular character and anastomose freely with each other in the meshes of the trabeculae, thus differing from the arteries between which, in the substance of the spleen, the anastomoses are few. From this description it will be seen that the arteries terminate and the veins commence in capillaries which are in direct communication with the pulp, so that the blood, in order to pass from the one to the other, has to traverse it. There are, however, a few arterial capil- laries in the trabecula) and capsule of the spleen which terminate in the veins in the usual manner. The lymphatics of the spleen are in two sets—trabecular and perivascular; the former run in the trabecula) and communicate Fig. 462.—Section of spleen, showing a .Malpighian body. b. Injected capillaries, c. Artery entering the lymphoid tissue of the Malpighian body. 756 SUPRA-RENAL BODIES. with a superficial set in the capsule; the latter commence in the lymphoid tissue around the arteries, and in the Malpighian corpuscles. The nerves form the splenic plexus and are derived from the solar plexus. THE SUPRA RENAL BODIES. The supra-renal bodies or supra-renal capsules are two small yellowish and battened bodies surmounting the kidneys, and inclin- ing inwards towards the vertebral column. The right is somewhat three-cornered in shape, the left -semilunar ; they are connected to the kidneys by the common investing areolar tissue, and each capsule is marked on its anterior surface by a fissure or hilum which appears to divide it into two lobes. The right supra-renal body is closely adherent to the posterior and under surface of the liver, the left lies in contact with the pancreas and spleen. Both bodies rest against the crura of the diaphragm on a level with the tenth dorsal vertebra, and by their inner bor- der are in relation with the great splanchnic nerve and semilunar ganglion. They are larger in the foetus than in the adult, and appear to be more active during embry- onic life. Each body is about one and three-quarter inches in height, an inch and a quarter in width, and from two to three lines in thickness ; they weigh from one to two drachms. Structure.—A section of a supra-renal body shows that it has externally a fibrous investment or capsule, and internally is divisible into two portions, that nearest the surface and forming the great bulk of the organ being firm, striated, and of a brownish-yellow colour ; this is the cortical portion. The central or medullary portion is of a brownisli-black colour, and so soft that many anatomists have erroneously supposed a cavity to exist in it. The cortical portion consists of a stroma supporting cells, the cells being arranged in groups, the largest and most important of which assume the appear- ance of columns. Arnold has divided the cortical portion into three layers. The outer he calls the zona glomerulosa; in it the cell groups are round or oval in shape. The next layer he names the zona fasciculata; it is much the thickest of the three layers, and forms the bulk of the organ ; in it the cells are arranged in cohimns placed at right angles to the surface of the organ. The third layer of the cortex is a v.ery narrow one called zona reticularis; here the stroma is equally distributed, and the cells are consequently not arranged in groups. The cells of the cortex are polyhedral in shape, and consist of granular protoplasm containing oil globules ; each Fig. 463.—Section of the supra - renal body of a foetus, showing the lower notch by which it rests on the sum- mit of the kidney r, and the anterior notch by which tiie veins issue v. It also shows the distinction be- tween the cortical and medullary substance. STRUCTURE OF THE SUPRA-RENAL BODIES. 757 cell has a clear spheroidal nucleus. The medullary portion is separated from the cortical by loose areolar tissue ; it is traversed by large veins, and is composed of a reticular stroma enclosing groups of cells which differ from those of the cortex in being coarsely granular, devoid of oil globules, and many of them branched. The medulla is rich in nerves, and some observers have sup- posed the branched cells of this portion of the organ to be nerve cells, Luschka even stating that lie has traced nerve fibres in connection with them ; this statement is not confirmed by other observers. The blood-vessels of the supra-renal bodies are very numerous. The arteries, about twenty in number, proceed from the aorta, phrenic, cceliac, and renal trunks ; they enter the cortical substance at every point of its surface, the greater number dividing into minute twigs and forming a plexus in the cortical layer ; while others continue onwards to the me- dullary substance, and either terminate in the medullary plexus or cross the medullary substance to re-enter the corti- cal layer and contribute to the formation of its capillary plexus. The veins take their origin from the capillary plexus by minute venules, which unite to form the supra-renal vein. The supra- renal vein runs through the centre of the medullary sub- stance, and issues from the supra-renal body at the hilum on its anterior surface, to terminate on the right side in the inferior vena cava, on the left in the renal vein. The lymphatic vessels are numerous, and belong to the exterior of the organ ; they terminate in the lumbar glands. The nerves are very numerous, and derived from the renal and phrenic plexus, some filaments being received from the phrenic and vagus nerves ; Kolliker counted as many as thirty-three trunks, composed of dark-bordered nerve-fibres and provided with isolated Fig. 464.—Vertical section of supra renal body. 1. Cortex. 2. Medulla, a. Cap- sule. b. Zona glomerulosa. c. Zona fasci- culata. d. Zona reticularis, e. Medullary substance. /. Section of a vein. 758 KIDNEYS. ganglia. They are distributed to the medullary substance only, in which they form a rich nervous plexus. THE KIDNEYS. The kidneys, the secreting organs of the urine, are situated in the lumbar regions, behind the peritoneum, and at each side of the verte- bral column, corresponding to the bodies of the last dorsal and two upper lumbar vertebrae, and extending from the eleventh rib to near the crest of the ilium ; they approach the vertebral column by their upper end. Each kidney is between four and five inches in length, about two inches and a half in breadth, somewhat more than one inch in thickness, and weighs about 40 oz. in the male and rather less in the female. The kidneys are usually surrounded by fat; they rest on the crura of the diaphragm, on the anterior lamella of the aponeurosis of the transversalis muscle, which separates them from the quadratus lumborum, and on the psoas magnus. The right kidney is somewhat lower than the left, from the position of the liver ; it is in relation, by its anterior surface, with the liver and descending portion of the duodenum, which rests against it; and is covered in by the ascending colon. The left kidney, higher than the right, is covered, in front, by the great end of the stomach, the spleen, tail of the pancreas, and descending colon. The anterior surface of the kidney is convex, the posterior is fiat ; the superior extremity is larger than the inferior, and is in relation with the supra-renal capsule ; the convex border is turned outwards towards the parietes of the abdomen ; the concave border looks inwards towards the vertebral column, and presents a deep notch (liilum renale), which leads to a cavity, or sinus, within the organ. In the sinus renalis are situated the vessels and nerves of the kidney and the expansion of the excretory duct called the pelvis of the kidney. At the liilum these vessels are so placed that the renal vein is in front of the artery, and the pelvis and ureter behind. The kidney is surrounded by a thick layer of fat, contained in the meshes of a loose areolar tissue, forming the adipose capsule, and separating the kidney at the back from the diaphragm, ante- rior layer of the fascia lumborum, and ilio-hvpogastric nerve ; and internally from the edge of the psoas. Within this, the organ is enclosed in a fibrous capsule, which is thin, firm, and whitish, and composed of dense areolar tissue intermingled with elastic fibres, and beneath this an incomplete layer of unstriped muscle. The capsule is connected by its inner surface with the substance of the gland by fine areolar tissue, but so loosely as to be easily separable. The substance of the kidney is dense and fragile, and when divided by a longitudinal incision, exhibits two structures, different in colour and texture—an external vascular or cortical portion, and an internal tubular or medullary portion. The medullary portion consists of from eight to fifteen dark red conical masses, having their apices or papillae directed towards the pelvis, and their bases STRUCTURE OF THE KIDNEYS. 759 to the cortical substance ; these conical masses are the pyramids of Malpighi. By their bases they are inseparably con- nected with the cor- tex ; their apices, or papillae (of a paler colour than the rest of the pyramids) project like little teats into the sinus of the kidney, being received into cavi- ties lined with mu- cous membrane and called calices, which are subdivisions of the renal pelvis. The pyramids are com- posed of an assem- blage of straight tubules, the tubuli recti, which open into a shallow depression on the summit of the papilla, and divide into branches at acute angles as they proceed from the apex to the base of the pyramid ; these cause the radiate striation observable on a vertical section of the pyramids. The cortical portion, distinguished by its bright red colour, granu- lar appearance, and softer texture, forms the surface of the organ, surrounding the base of each pyramid and penetrating between them to the sinus renalis. It therefore forms septa between the pyramids (septa vel columnce Bertini), and marks the original com- position of the kidney of separate lobes. It is com- posed of blood-vessels, with the cortical fasciculi and ultimate terminations of the tubuli uriniferi, held to- gether by a delicate stroma of areolar tissue. Fig. 465.—Section of the kidney, sur- mounted by the supra-renal body ; the swellings on the surface mark the original constitu- tion of the organ of lobes. 1. Supra- renal body. 2. Cortical portion of the kidney. 3, 3. Medullary portion, consisting of cones. 4, 4. Two of the pa- pillse projecting into their corresponding calices. 5, s> S- The three infundibula; the middle 5 is situated in the mouth of a calyx. 6. Pelvis. 7. Ureter. Fig. 466.—Vertical section of kidney, u. Ureter. P. Pelvis. «, a. Renal arteries, ct. Cortex, m. Pyramid of Malpighi, c. Calix. u.t. Cut urini- ferous tubules, p. Papilla, i. Intertubular stroma, mr. Medullary rays. 760 Uriniferous tubules.—The kidney is a compound tubular gland, its secreting structure being formed by the uriniferous tubules. These commence by spherical dilatations, the Malpighian capsules, in the labyrinth of the cortex, each capsule enclosing a tuft of blood- KIDNEYS. Fig. 467.—On the left of the figure the arrangement of the blood-vessels of the kidney is shown, on the right the course of the uriniferous tubules, vs. Vemr stelluhc. vi. Interlobular veins, vr. Venae reetse. mv. Veins of medullary part. vp. Veins of papillfc. ai. Interlobular artery. <7. Glomerulus, or. Arterial rectK. am. Arteries of medullary part. A. Cortex. B. Boundary zone. C. Papillary zone of medulla, a, a'. Superficial and deep layers of cortex, free of glomeruli. 1. Malpighian capsule. 2. Neck. 3. First convoluted tubule. 4. Spiral tubule of Schachowa. 5. Descending limb of looped tubule of Henle. 6. Bend. 7, 8, 9. Ascending limb. ic. Irregular tubule. 11. Second convoluted tubule. 12. Junctional tubule. 13,14. Collecting tubule. 15. Excretory tubule. vessels, the Malpighian tuft or glomerulus ; the capsule and tuft together constituting the Malpighian body. The tubule, on issuing from the capsule, is constricted by a narrow neck, then widens out and becomes convoluted, forming the first convoluted tubule; next it passes towards one of the pyramids of the medulla, becoming STRUCTURE OF THE KIDNEYS. 761 spiral as it descends—the spiral tubule of Schachowa. Entering the pyramid, the tubule becomes much narrower, and after a shorter or longer course bends on itself and again runs towards the cortex, becoming larger as it ascends, these two parts form the descending and ascending limb of the looped-tubule of Henle. On again entering the cortex, the uriniferous tubule becomes extremely irre- gular in outline, and is distinguished as the irregular tubule, and then again becoming convoluted forms the second convoluted tubule. The latter passes into a small junctional tubule, by which it is connected with one of the tubules in the Malpighian pyramids, called collecting tubules—these last uniting to form the excretory tubules already described as opening on to the apex of the papilla. The part of the pyramids near the cortex is called the boundary zone ; in it the tubules are collected into bundles, separated from each other by groups of small blood-vessels ; and these, as they radiate from the pyramids into the cortex, form the medullary rays ; the cortical substance between and around their ends is called, on account of its intricacy, the labyrinth of the cortex. The Malpighian body, first convoluted tubule, irregular tubule, and second convoluted tubule, are in the labyrinth ; the spiral and junctional tubule are in the medullary rays ; the descending and ascending limbs of the looped tubule of Henle, and the collecting tubules are in the boundary zone. The tubules are formed by a basement membrane supporting epithelium ; they vary considerably in width in different parts of their course. Xear the apex of the papilla the excreting tube measures from *7T to .jljj of an inch in width. Epithelium of the tubules.—The epithelium of the excretory tubes is columnar, and the lumen is large in proportion to the depth of the cells ; that in the collecting tubules is cubical, but the cells vary considerably as regards regularity and thickness. In the junctional tubules the epithelium is cubical but somewhat flattened, and the lumen is relatively large. The second convoluted tubule (intercalary tubule) has an epithelium the cells of which are rather long, have a highly refractive proto- plasm and a lame nucleus, and possess at their bases lateral pro- jections which dovetail into those of neighbouring cells. The irregular tubule is distinguished by the fact that, notwithstanding its irregularities in size and shape, the lumen is nearly the same throughout, this being brought about by the inequalities in the size of the cells ; their protoplasm appears to be made up of a series of minute rods, placed vertically to the surface of the basement membrane. A difference exists in the appearance presented by the ascending and descending limb of the looped tubules of Henle ; in 762 the latter the lumen is distinct, and the cells form a flattened layer thickened here and there by the presence of nuclei ; in the former the cells approximate in character to those of the convoluted tubes, and although the whole tube is wider than the de- scending limb the lumen is much narrower. In the spiral tube of Schachowa the lining cells are columnar, are firmly united by inter- locking processes, and have the part next the 1 lasement membrane apparently composed of vertical rods; towards its termination, however, the cells become shorter, less fibrillated, and split into ridges with furrows between. The first con- voluted tube has an epi- thelium which corre- sponds in all essentials with that of the spiral tube. The neck of the Malpighian capsule is lined with cubical epithelium, and in many animals this is furnished with cilia ; but in the human kidney they have not up to the present been demonstrated. The Malpighian bodies are found only in the cortical substance of the kidney, and form the most distinctive feature of the structure of the organ. Two vessels are connected with each Malpighian body, one entering it, afferent vessel, and the other leaving it, efferent vessel; the glomerulus and its vessels resemble in appearance fruit supported on its stalk. The capsule is lined by a flattened epithe- lium, which may also be traced on to the surface of the glomerulus, being most distinct in the latter situation where the capsule opens into the first convoluted tube. The epithelial cells in the capsule are supported by a basement membrane formed of flattened epithe- lial cells. Blood-vessels.—The renal artery, derived from the aorta, enters the kidney between the vein and ureter, and divides into four or five large trunks which pass between the papillae to enter that portion of the cortical substance placed between the pyramids of the medulla ; here they divide and subdivide, and give off small branches, which communicate across the bases of the pyramids so as to form imper- fect arches between the cortical and medullary substance. From KIDNEYS. Fig. 468.—Epithelium of tlie uriniferous tubules. 1. From ascending limb of looped tubule of Henle. 2. From spiral tubule. 3. From collecting tubule. 4. From convoluted tubule. 5. From irregular lubule. VESSELS OF THE KIDNEYS. 763 these arches are given off interlobular arteries, placed between the medullary rays, and giving off afferent vessels on each side to the Malpighian bodies. In the Malpighian body the afferent artery divides into from five to eight branches, and each of these branches into a bundle of capillaries ; they form a spherical vascular tuft, the glomerulus, and are again gathered up into a single branch, the efferent vessel. The efferent vessel is smaller than the afferent; it quits the Fig. 469.—Plan of the renal circulation. a. Interlobular branch of the renal artery giving off several afferent ves- sels. 1. An afferent twig to the capil- lary tuft contained in the Malpi- ghian body, to,- from the Malpighian body the uriniferous tube is seen taking its tortuous course to t. 2, 2. Efferent vessels; that which proceeds from the Malpighian body is smaller than the corresponding affeveut branch, p, p. The capillary plexus, ramifying on the uriniferous tube. This plexus receives its blood from the efferent vessels, 2, 2 ; and transmits it to the branch of the renal vein, v. Malpighian body by the side of the latter and divides into capillary vessels, which form a rich plexus around the uriniferous tubules of the labyrinth, and eventually terminate in the renal veins. Those efferent vessels which are nearest to the base of the pyramids take a straight course(arteriolce rector)between the straight tubules, and giving off but few branches in their course, also pass into a capillary plexus which surrounds the tubules and terminates in the venulce rectce. The renal artery also gives off branches to the capsule of the kidney which anastomose freely with branches of the lumbar arteries. The veins of the kidney commence at the surface by minute converging venules, the stellated vessels, in the corti- cal substance where they form the interlobular veins, and in the pyramids of Malpighi, where they constitute the venulse rectse ; proceeding from these three sources, they unite to form the branches of the renal vein, which termi- nates in the vena cava by a single large trunk at each side ; the left renal vein receiving the left spermatic vein. The renal veins are less capacious than the renal arteries, they have no Fig. 470.—Transverse section through a Mal- pighian pyramid, a, a. Collecting tubule witli columnar epithelium, b, b. Descend- ing limb of looped tubule of Henle, lined by flat cells, c, c. Ascending limb with thick granular cells, d, d. Transverse sec- tion of vessels, e, e. Intertubular stroma. 764 URETER. valves, and carry blood distinctly purer than that brought to the kidneys by the arteries. The lymphatic vessels consist of a superficial set placed beneath the capsule, and of a deep set which accompanies the deep blood-vessels ; both sets terminate in the lumbar glands. The nerves are derived from the renal plexus, which is formed partly by the solar plexus, and partly by the third splanchnic nerve. The renal plexus gives branches to the spermatic plexus, and branches which accompany the ureters. Intertubular Stroma.—The tubules and vessels of the kidney are held together and supported by very fine connective tissue, that in the neighbourhood of the vessels and around the Malpighian bodies being fibrous in its character. The stroma is more abundant in the cortical than in the medullary portion, and is there chiefly formed of connective-tissue corpuscles. The cavity of the kidney is occupied by a membranous bag, the pelvis renalis, which gives off three processes, the infundibula, one for each extremity, and one for the middle of the organ ; and the infundibula give off smaller pro- cesses termed calices, which em- brace the papilla; and form a sepa- rate pouch around each ; the calyx being firmly attached to the base of the papilla and continuous with the fibrous capsule. Externally the sac of the pelvis renalis contracts into its excretory duct, the ureter. Some- times there is no true pelvis, the calices uniting to form two or more infundibula which join to con- stitute the ureter. Fig. 471.—Two varieties in the ar- rangement of the pelvis and infun- dibula of the kidney. Ureter. The ureter (ovpea>, I pass water) is a membranous tube of about Ihe diameter of a goose-quill, and nearly eighteen inches in length, continuous superiorly with the pelvis of the kidney, and con- stricted interiorly, where it lies in an oblique direction between the muscular and mucous coat of the base of the bladder, and opens on its mucous surface. Lying along the posterior wall of the abdomen, it is situated behind the peritoneum, and is crossed by the spermatic vessels ; in its course downwards it rests against the anterior surface of the psoas, and crosses the common iliac artery and vein, and then the external iliac vessels. Within the pelvis it crosses the hypogastric cord and vas deferens in the male ; and runs by the side of the cervix uteri and upper part of the vagina in the female. There are sometimes two ureters to one kidney. The ureter, the pelvis, the infundibula, and the calices are com- posed of three coats, external or fibrous, middle or muscular, and internal or mucous. The fibrous coat consists of condensed areolar tissue, intermingled with tine elastic fibres. The muscular coat is made up of muscular fibres of the smooth kind, disposed in three layers, external and internal longitudinal, and a circular layer between. The muscular coat is thick in the ureter and pelvis renalis, thin on the calices, and ceases altogether at the attachment of the latter to the papillae. The mucous coat is thin, vascular, and without villi; on the papillae it is connected with the substance of the pyramids, and is continuous with the uriniferous tubules, while inferiorlv it becomes blended with the mucous membrane of the bladder. The epithelium of the mucous coat is thick, and com- posed of several layers of nucleated cells, which are small and round next the membrane ; of larger size and cylindrical or pear-sha] >ed in the middle; and large and cubical at the surface, sometimes measuring of an inch in breadth, and not unfrequently contain- ing two nuclei. Many of the superficial cubical cells are excavated on their under surface into little depressions, into which the heads of the pear-shaped cells of the middle layer fit. URINARY BLADDER. PELVIS. The cavity of the pelvis is that portion of the great abdominal cavity which is included within the hones of the pelvis, below the level of the pectineal line and promontory of the sacrum. It is hounded hy the cavity of the abdomen above, and by the perineum below ; its internal parietes are formed in front, below, and at the sides, by the peritoneum, pelvic fascia, levatores ani, and obturator internus muscles ; and behind, by the coccygei muscles, sacro-ischiatic ligaments, pyriformes muscles, sacral plexus of nerves, sacrum, and coccyx. The viscera of the pelvis in the male are—the urinary bladder, prostate gland, vesiculse seminales, and rectum. Tlie bladder is a hollow membranous viscus, triangular and flattened against the pubes when empty, ovoid when distended, situated behind the pubes and in front of and upon the rectum. It is larger in its vertical diameter than from side to side ; and its long axis is directed from above, obliquely downwards and backwards. Braune has shown that in the erect posture the neck of the bladder is the lowest part of the viscus. It is divided into body, fundus, base, and neck. The body comprehends the middle zone of the organ; the summit or superior fundus, its upper segment; the base or inferior fundus, the lower broad extremity which rests on the rectum ; and the neck, the narrow constricted portion which is applied against the prostate gland. Relations.—When moderately distended the bladder is in rela- noti, in front, with the pubes (some retro-pubic fat intervening), and URINARY BLADDER. 766 URINAltY BLADDER. the anterior true ligaments ; behind, with the small intestines occu- pying the recto-vesical pouch ; below, with the rectum, vesicula) seminales, vasa deferentia, ureters, and recto-vesical fascia, and at each, side by the vas deferens, lateral true ligament, ureter and obliterated hypo-gastric artery. The summit is connected with the abdominal wall by means of the urachus, and the neck is surrounded by the prostate gland. It is retained in position by ligaments which are divisible into true and false : the true ligaments are five in number, two anterior, two lateral, and the cord of the urachus ; the false ligaments are folds of the peritoneum, and are also live in number, two posterior, two lateral, and one superior. The anterior ligaments (joubo-prostatic) are formed by the visceral layer of the pelvic fascia, in its passage from the inner surface of the pubes at each side of the symphysis to the neck of the bladder and prostate gland. Between the two ligaments the dorsal vein of the penis runs. The lateral ligaments are also formed by the visceral layer of the pelvic fascia, in its passage from the white line to the sides of the prostate gland and bladder. The ligament of the urachus is a fibrous cord resulting from the obliteration of the allantoic canal in the embryo. It proceeds from the summit of the bladder, and ascends along the linea alba to the umbilicus. The posterior false ligaments are the folds of peritoneum pass- ing from the rectum and sides of the sacrum to the bladder; they contain the ureters, and the vessels and nerves of the bladder. The lateral false ligaments are formed by the passage of the peritoneum from the side of the pelvis to the bladder; they cover the upper and posterior half of its lateral wall. The obliterated hypogastric artery lies along the line of reflection of the membrane. The superior or suspensory false ligament is the fold of peri- toneum caused by the prominence of the cord of the urachus and the cords of the obliterated hypogastric arteries. Structure.—The bladder is composed of four coats, external or serous, muscular, areolar, and mucous. The serous or peritoneal coat covers the whole posterior surface of the bladder, and the under surface as far forwards as the entrance of the ureters, where it is attached to the back part of the recto- vesical fascia. At the sides it is limited by the obliterated hypo- gastric arteries, and consequently only invests the upper and poste- rior part; on the anterior surface it is entirely absent; above, it covers the part behind the urachus. The muscular coat consists of three layers of unstriped muscular fibre ; external or longitudinal, middle or circular, and internal, which is also longitudinal. The external layer, or detrusor urinae, consists of parallel longitudinal fasciculi which take their origin from the anterior ligaments of the bladder, thence named tendons of the detrusor urinse; they spread out upon the upper surface of the STRUCTURE OF THE BLADDER. 767 prostate gland and ascend upon the anterior surface of the bladder to the fundus, where they are inserted into the subserous tissue, some being continuous with the longitudinal fibres of the posterior- surface of the organ, and others prolonged upon the urachus. The longitudinal fascicnli of the posterior surface and sides of the bladder, attached superiorly to the subserous tissue, and partly continuous with those of the opposite aspect, while some are prolonged upon the urachus, are attached inferiorly to the prostate gland, those in the middle line being lost in the deep muscular layer of the neck of the bladder. The middle layer consists of circular fibres which are most numerous at the cervix, where they form a moderately thick stratum, the sphincter vesicse, and are then continued onwards around the prostatic urethra. The internal layer (submucous layer ; Ellis), thinner than the preceding, is composed of fibres which are oblique and scattered in the fundus and body of the bladder, but become longitudinal in its lower part and base, and are continued into the urethra. At the base of the bladder this layer is strength- ened by the longitudinal fibres of the ureters. The three muscular layers communicate with each other by means of a frequent inter- change of fasciculi. The areolar or submucous coat is the thick layer of areolar tissue interposed between the mucous and muscular coat, and form- ing the bond of union between them. The mucous coat is thick and smooth, of a pale-rose colour, and exactly moulded on the muscular coat, to which it is loosely con- nected by the submucous coat, When the bladder is empty it is thrown into folds or rugce, excepting in the triangular area "at the neck called the trigone. The mucous membrane is continuous through the ureters with the lining membrane of the pelvis of the kidney, and through the urethra with that of the seminiferous ducts, prostate gland, and Cowper’s glands. It is provided with a stratified epithelium similar to that of the ureters, the deeper cells of which are conical or fusiform ; the intermediate pyriform, and the superficial spheroidal or flattened, and of unequal size. It has a thin layer of muscularis mucosae on its outer surface. The mucous membrane is rich in vessels, which are most abundant, as are the nerves, in the cervix and fundus ; the nerves are not numerous. On the internal surface of the base of the bladder is a triangular smooth plane, the trigonum vesicse or vesical trigone (Fig. 474), on which the mucous membrane is paler and thinner than the rest, and is not thrown into folds when the viscus is empty. Calculi resting 011 this part give rise to much suffering on account of the greater number of nerves distributed to the cervix vesicse. The trigone is bounded at each side by the raised ridge, corresponding with the muscles of the ureters, at each posterior angle by the openings of the ureters, and, in front, by a slight elevation of tlie mucous membrane at the entrance of the urethra, called uvula vesicce. The external surface of the base of the bladder corresponding with the trigone is also triangular, and separated from the rectum 768 by the recto-vesical layer of pelvic fascia. It is bounded behind by the recto-vesical fold of peritoneum and at each side by the vasa deferentia, which converge almost to a point at the base of the prostate gland. It is uncovered by peritoneum, and for this reason it is through this space that the opening is made in the recto-vesical operation for puncture of the bladder. Vessels and Nerves.—The arteries of the urinary bladder are the superior vesical, three or four small branches which proceed from URINARY BLADDER. Fig. 472. — Side view of the vis- cera of tlie male pelvis, in xitu. The right side of the pelvis lias been removed by a vertical section made through the os pubis near the symphysis; and another through the middle of the sacrum. 1. Di- vided surface of the os pubis. 2. Divided surface of the sacrum. 3. Body of the bladder. 4. Its superior fundus; from the apex is seen passing up- wards the ura- chus. 5. Base of the bladoer. 6. Ureter. 7. Neck of the bladder. 8, 8. Pelvic fascia ; the fibres immediately above 7, arc given off from the pelvic fascia, and represent the anterior ligaments of the bladder. 9. Prostate gland. 10. Membranous portion of the urethra.,11. Triangular ligament. 12. One of Cowper’s glands lying beneath the membianous portion of the urethra. 13. Bulb of corpus spongiosum. 14. Dody ol corpus spongiosum. 15. Right crus penis. 16. Upper part of first portion of the rectum 17. ltecto-vesical fold of peritoneum. 18. Second portion of rectum. 19. Kigiit vesicula seminalis. 20. Vas deferens. 21. The rectum covered by the descending layer of the pelvic fascia, just as it is making its bend backwards to constitute tne third portion. 22. Part of the levator ani muscle investing the lower part or the rectum. 23. External sphincter ani. 24. Interval between Colles fascia am the anterior layer of the triangular ligament; they are seen to be continuous beneath the figure. the commencement of the hypogastric artery, previously to its com- plete obliteration : an inferior vesical, from the internal iliac, the latter is distributed to the base of the bladder, vesiculae semmales, and prostate gland. The veins are numerous and of large size, and form a plexus around the neck and at the base of the bladder ; the plexus communicates with the prostatic plexus and lnemorrhoidal veins. The nerves of the bladder are derived from the infenoi hypogastric plexuses and their communications with the third and fourth sacral nerves. They form a gangliated plexus on the blood- vessels, and also form a network under the epithelium. PLATE 26. Fir/. 2 Firj. / A. Urethra. B. Bulb. C. Prostate. D. Crus penis with ischio-cavernosus. E. Triangular ligament (cut to show Cowper’s glands). F. Anus. G. Tuber ischii. H. Coccyx. Fig. 2.—The Levator Ani Removed, and Rectum turned down to show the Prostate and Neck of Bladder. Fig. 1.—The Bulbo-cavernosus Removed to show the Bulb of the Urethra, and the Triangular Ligament partially Removed to show Cowper’s Glands. THE MALE PERINEUM. PLATE 26. I, Gluteus maximus. K. Levator ani (cut). L. Pudic artery. M. Membranous urethra. N. Vesicula seminalis. O. Great sacro-sciatic ligament. P. Base of bladder. Q. Yas deferens. PEOSTATE GLAND. 769 PEOSTATE GLAND. The prostate gland (ttpotarrjfu, to stand in front of) is situated in front of the neck of the bladder, behind the triangular ligament and pelvic fascia, and upon the rectum, through which latter it may be felt with the finger. It measures about one and a half inches across at its base, is about an inch and a quarter from base to apex, and its depth is nearly an inch ; it weighs from six drachms to an ounce. It surrounds the commencement of the urethra for a little more than an inch of its extent, and resembles a Spanish chestnut both in size and form ; the base being directed backwards towards the neck of the bladder, the apex forwards, and the flattened side towards the rectum. It is retained firmly in position by the anterior and lateral ligaments of the bladder, and by a process of the pelvic fascia, which forms a sheath around it. It consists of three imperfectly defined lobes, two lateral and a middle lobe or isthmus ; the lateral lobes are distinguished by an indentation at the base of the gland, and a slight furrow on its upper and lower surface. The third lobe (prometria) is a small mass which passes between the two lateral Fig. 473.—Transverse section through the middle of the prostate gland, u. The urethra, encroached on below by the caput gallinaginis. s. Sinus pocularis. de. Ejaculatory ducts. The upper m shows the deep sphincter muscular fibres, the lower m the muscular bands penetrating into the lateral lobes, p. Glandular substance. lobes at the back part of the under sin-face of the organ; it is generally imperfectly marked in the normal state of the gland, but becomes evident when enlarged ; when prominent it corresponds to the elevation at the neck of the bladder called the uvula. Structure.—It is covered by a thick and strong fibrous capsule, derived from the recto-vesical fascia behind and deep layer of the triangular ligament in front, and divisible into two layers, between which the prostatic plexus of veins is placed. Its proper structure is composed of smooth muscle and glandular tissue, the latter being not more than one-third or one-fourth of the whole, and consisting of from thirty to fifty compound racemose glands, of a pyriform shape. Its secretion is poured into the prostatic portion of the urethra by fifteen or twenty excretory ducts. The ducts of the lateral lobes open into the urethra at each side of the veru mon- tanum ; those of the third lobe open upon and behind the veru. The greater part of the prostate is formed of unstriped muscle mixed with white and yellow fibrous tissue ; the muscle fibres are many of them arranged circularly around the urethra, and are continuous with those of the sphincter vesicge ; others pass transversely across 770 VESICULJE SEMINALES. in front and behind the urethra, and radiate into the lateral lobes The urethra, in passing through the prostate, lies one-third nearer its upper, than its lower, surface. The arteries of the prostate are small, and derived from the in- ferior vesical and middle hannorrhoidal; they distribute numerous capillaries to the glandular structure of the organ. The veins form a rich plexus in the submucous tissue of the urethra, and another of larger vessels on the exterior of the gland ; the latter receives from the front the veins of the penis, and terminates in the vesical plexus. Lymphatics are distributed \v ith the veins between the two lavers of the capsule. VESICULA SEMINALES. On the midei sui face of the I13.se of tlie bladder, 3iid converging towards the base of tlie prostate gland, are two tabulated and some" wliat pyriform bodies, about two inches in length, the vesicula} seminales. Their upper surface is in contact with the base of the bladder ; the under side rests on the rectum, separated only by the recto-vesical fascia ; the larger extremities are directed backwards and outwards, and the smaller ends almost meet at the base of the prostate. They enclose between them a triangular space, which is bounded posteriorly by the recto-vesical fold of peritoneum, and corresponds with the trigonum vesicae on the inte- rior of the bladder. Each vesicula is formed by the con- volutions of a single tube, which gives off several irregular cfecal sacculi and branches. It is en- closed in a thin fibrous nienil >rane; and is constricted beneath the isthmus "'here 11 terminates in the ejaculatory duct. Thc'vas deferens’ somewhat enlarged and sacculated, lies along the inner border of ni* ,\esicula’ a.nc* 18 included in its fibrous investment; it unites with the vesicula beneath the isthmus of the prostate, in the forma- tion ot the ejaculatory duct. 1 be ej'aculatory duct is about three-quarters of an inch in nuf tl'.’./T'll runmn% f‘,nvar;ls’ fir8t between the base of the prostate « id the isthmus, and then through the tissue of the veru montanum, Fkj. 474.—Posterior aspect of the male bladder ; the serous covering is re- moved in order to show the muscular coat. 1. Body of the bladder. 2. Superior fundus. 3. In- ferior fundus or base. 4. Urachus. 3, 5. Ure- ters. 6, 6. Vasa defer- entia. 7, 7. Vesicuke seminales. The trian- gular area, bounded by the vasa deferentia and vesiculse seminales at either side, a dotted line above, and the figure 3 below, is the space cor- responding with the tri- gonum vesicse. The dotted line, forming the base of this triangular area, marks the limit of the recto-vesical fold of peritoneum. PENIS. opens on the mucous membrane of the urethra, by the side of or within the aperture of the sinus pocularis. The vesiculse seminales and vasa deferentia are partly covered by a muscular layer, compressor vesiculce et ductus seminalis (Ellis) ; which is brought into view on raising the recto-vesical fascia. This muscular layer consists of transverse and longitudinal fibres, the transverse fibres being the most superficial, and continuous with the posterior border of the prostate gland; the longitudinal fibres lying in contact with the vesiculse and vasa deferentia. In structure the vesiculse seminales are composed of three coats : external, a thin fibrous membrane, made up of condensed areolar tissue ; middle, a muscular coat, consisting of smooth muscular fibres arranged in two layers, longitudinal and circular ; and inter- nal, a thin mucous membrane, vascular, marked by a delicate reticulation of ridges and alveoli, and coated with a squamous epi- thelium of cells containing yellowish pigment granules. Opening on to the surface of the mucous membrane are a large number of tubular glands, which give to its surface a brownish-yellow colour. The vesiculse are covered externally and their convolutions held to- gether by a thin membrane of areolar tissue, and they are further invested by the recto-vesical fascia, and the muscular stratum already described. 771 MALE ORGANS OF GENERATION. The organs of generation in the male are—the penis and testicles, with their appendages. The penis is divisible into a body, root, and extremity. The body is surrounded by a thin integument, which is remarkable for the looseness of its connection with the deeper parts of the organ, and for containing no adipose tissue. The root is broad, and firmly adherent to the rami of the pubes and ischium by means of two strong processes, the crura, and connected to the symphysis pubis by an elastic fibrous membrane, the suspensory ligament. The extremity or glans penis resembles an obtuse cone, somewhat com- pressed from above downwards, and of a deeper red colour than the surrounding skin. At its apex is a small vertical slit, the meatus urinarius, which is bounded by two, more or less protuberant, labia ; and, extending backwards from the meatus, a grooved raphe, to which a loose fold of mucous membrane, the frsenum prseputii, is attached. Over the surface of the glans the integument takes on the characters of mucous membrane ; it is very intimately adherent to the tissue beneath it, is very vascular, and is covered with large papillae, some of which contain vascular tufts and others nerve endings. The base of the glans is marked by a projecting collar, the corona glandis, in the groove beneath which (fossa glandis) are placed the openings of numerous glands, the glandulse odoriferse PENIS. MALE ORGANS OF GENERATION. 772 Tysoni. The integument around the base of the glane forms a loose fold, the prepuce, which, in the collapsed state of the organ, may be drawn over the glans, but, in its distended state, is obliterated, and serves to facilitate its enlargement. The internal surface of the prepuce is lined by mucous membrane, which, as above described, is reflected over the glans, and, at the meatus urinarius, is continuous with the mucous lining of the urethra. The superficial fascia of the penis is thin, and its areolar struc- ture free from fat; it is continuous with the superficial fascia of the abdomen above, and with the dartos and superficial fascia of the perineum below. The suspensory ligament of the penis is an elastic fibrous mem- brane of triangular form, attached by its apex to the symphysis Pubis ; and by its base, to the body of the penis. Near the latter attachment it separates into two layers, to give passage to the dorsal vessels and nerves of the penis. The penis is composed of the corpus cavernosum and corpus spongiosum, and contains in its interior the longest portion of the urethra. The corpus cavernosum is distinguished into two lateral portions (corpora cavernosa) by an imperfect septum and a superior and in- ferior groove, and is divided posteriorly into two crura. It is firmly adherent, by means of its crura, to the rami of the ] tubes and ischium ; and each crus, previously to its junction with its fellow, pre- sents a slight enlargement, which was named by Kobelt, the bulb. The corpus cavernosum forms, anteriorly, a single rounded extremity, which is received into a fossa in the base of the glans ; the superior groove lodges the dorsal vessels of the penis, and the inferior receives the corpus spongiosum. Its fibrous tunic is thick, elastic, and extremely firm, and sends a number of fibrous bands and cords (trabeculae) inwards from the inferior groove, which cross the interior in a radiating direc- tion, and are inserted into the inner walls of the tunic, lliese trabeculae are most abun- . dant at the middle line, where they are ranged vertically, side by side, somewhat like the teeth of a comb and constitute the imperfect partition of the corpus cavernosum called septum pectiniforme. The septum is more complete at its posterior than towards its anterior part. the tunic of the corpus cavernosum consists of two layers of fibrous fasciculi. The external is longitudinal and forms a kind of close net by the frequent interchange ot fibrous bundles; it is common to t lie two corpora cavernosa. The internal, less thick, forms a circle around each lateral mass, and also constitutes the septum pectini- torme. I rom its anterior extremity it gives off small fibrous bands, Fig. 475.—Transverse sec- tion of the penis. 1. Dorsal vein. 2. Dorsal artery. 3. Dorsal nerve. 4. Artery of corpus cavernosum. 5. Septum peetiniforme. 6. Ure- thra, surrounded by corpus spongiosum. PENIS. 773 which are prolonged into the substance of the glans penis. The fibres of the fibrous coat penetrate into the interior, and there form the trabemdce of the cavernous erectile tissue. The corpus spongiosum is situated along the under surface of the corpus cavernosum, in its inferior groove. It commences by its posterior extremity between and beneath the crura penis, where it forms an enlargement, the bulb, and terminates anteriorly by another expansion, the glans penis. Its middle portion, or body, is nearly cylindrical, and tapers gradually from the posterior to the anterior extremity. The bulb is adherent to the triangular liga- ment by means of a prolongation of fibrous membrane ; in the rest of its extent the corpus spongiosum is attached to the corpus caver- nosum by areolar tissue, and by veins which pass upwards to reach the dorsal vein. It is composed of erectile tissue, enclosed in a dense fibrous layer much thinner than that of the corpus caver- nosum, and contains the spongy portion of the urethra, which lies nearer its upper than its lower wall. The bulb shows a tendency to division into two lobes, an appearance which is due to the existence of a thin longitudinal septum in its interior. The fibrous tunic of the corpus spongiosum, unlike that of the corpus cavernosum, consists only of circular fibres which are re- flected inwards along the middle line, forming a septum which is complete only in the bulb ; the reflected fibres of this septum em- brace the urethra through its entire length, and exclude the latter from the proper structure of the corpus spongiosum. Erectile tissue is a peculiar cellulo-vascular structure, entering in considerable quantity into the composition of the organs of genera- tion. It consists of bands of fibrous and elastic tissue (with a few muscular fibres) which pass from the capsule of the organ into its interior, and there divide and unite in such a manner as to produce a system of cavities communicating freely with each other. The cavities are smaller in the glans penis, corpus spongiosum, and cir- cumference of the corpus cavernosum than in the central part of the latter, where they are large and dilated ; they are lined by a layer of flattened endothelial cells, continuous with those lining the arteries and veins. The cavernous spaces are at all times filled with blood, but become overcharged and distended during erection of the organ, in consequence of pressure upon its large veins retarding the venous flow. The arteries are convoluted in tbe passive state of the penis, but straightened in its distended condition ; they terminate in large capillaries, which do not form a plexus, as in other situations, but open directly into the cavernous spaces. Some of the finer twigs of the arteries have a peculiar, twisted, and dilated or tendril-like appearance, first described by Muller under the name of arteries, helicince. The helicine arteries are somewhat dilated where they lie in the trabeculae, and are bound down by small fibrous bands, possibly for the purpose of limiting their distension. The venous plexus conveys the 1 flood into the efferent veins of the penis, by which it is returned to the general circulation. 774 MALE ORGANS OF GENERATION. Vessels and Nerves.—The arteries of the pen is are derived from the internal pudic ; they are—the arteries of the bulb, arteries of the cor- pus cavernosum, and dorsum of the penis. Its veins are superficial and deep. The deep veins run by the side of the deep arteries, and terminate in the internal pudic veins. The superficial veins escape in considerable number from the base of the glans, and con- verge on the dorsum penis, to form a large dorsal vein, which re- ceives other veins from the corpus cavernosum and spongiosum in its course, and passes backwards between two layers of the liga- mentum suspensor ium, and through the tri- angular ligament be- neath the arch of the pubes, to terminate in the prostatic plexus. The lymphatics ter- minate in the upper group of inguinal glands, while some of the deeper lymphatics take the course of the urethra and end in the pelvic glands. The nerves are derived from the pudic nerve, sacral plexus, and hypogastric plexus. Fig. 476.—Structure of the peripheral portion of the corpus cavernosum penis. 1, a, a. Superficial net- work. b: Deep network. 2. Connection of the arterial twigs (a, a) with the canals of the deeper cortical network. The urethra is the membranous canal extending from the neck of the bladder to the meatus urinarius. It is curved in its course, and composed of three layers, a mucous coat, submucous coat, and muscular coat. The mucous coat is thin and smooth ; it is con- tinuous internally with the mucous membrane of the bladder ; externally, with the investing membrane of the glans ; and at certain points of its extent, with the lining membrane of the numerous ducts which open into the urethra, namely, those of URETHRA. Cowper’s glands, prostate gland, vasa deferentia, and vesicnlse seminales. It is provided with a stratified squamous epithelium corresponding with that of the bladder, and has opening on to its surface numerous mucous recesses or crypts, and the ducts of the glands lying in the submucous tissue. The submucous coat is loose, and contains a convoluted vascular structure resembling erec- tile tissue ; it also contains numerous racemose mucous glands, which URETHRA. 775 Fig. 477.—Longitudinal section of the bladder, prostate gland, and penis, showing the urethra. 1. Urachus. 2. Recto-vesical fold of peritoneum. 3. Opening of the right ureter. 4. A slight ridge, formed by the muscle of the ureter, and ex- tending from the termination of the ureter to the commencement of the urethra. This ridge forms the lateral boundary of the trigonum vesicse. 5. Commencement of the urethra; the elevation of mucous membrane immediately below the figure is the uvula vesicse. The constriction of the bladder at this point is the neck of the bladder. 6. Prostatic portion of the urethra. 7. Prostate gland; the differ- ence of thickness of the gland above and below the urethra is shown. 8. Isthmus, or third lobe of the prostate, immediately beneath which the ejaculatory duct is seen passing. 9. Right vesicula seminalis ; the vas deferens is seen to be cut short off, close to its junction with the ejaculatory duct. 10. Membranous portion of the urethra. 11. Cowper's gland of the right side, with its duct. 12. Bulbous portion of the urethra; throughout the whole length of the urethra of the corpus spongiosum numerous lacume are seen. 13. Fossa navicularis. 14. Corpus cayer- nosum, cut somewhat obliquely to the right side, near its lower part. 15. Right crus penis. 16. Near the upper part of the corpus cavernosum, the section has fallen a little to the left of the middle line ; a portion of the septum pectiniforme is consequently seen. Tiiis figure also indicates the thickness of the fibrous in- vestment of the corpus cavernosum, and its abrupt termination at the base of (17) the glans penis. 18. Lower segment of the glans. 19. Meatus urinarius. 20. Corpus spongiosum. 21. Bulb of the corpus spongiosum. open on the surface of the mucous membrane {glands of Littre). The glands are most abundant along the floor of the urethra, espe- cially in the bulbous portion. The muscular coat consists of unstriped muscular fibres, the outer layer of which is arranged circularly and is continuous with the circular muscular layer of the bladder ; the inner layer is longitudinal. The urethra is about eight inches in length, and divided into a prostatic, membranous, and spongy portion. 776 MALE ORGANS OF GENERATION. The prostatic portion, about one and a quarter inches in length, is situated in the prostate gland, about one-third nearer its upper than its lower surface, and extending from its base to its apex. It is the widest part of the urethral canal; and measures about one-third of an inch at the neck of the bladder, and nearly half an inch in the middle of the prostate ; it then narrows to about one quarter inch as it passes into the membranous portion. On its floor is a longitu- dinal ridge, the veru montanum, or caput gallinaginis; and at Fig. 478.—The bul- bous, membran- ous, and prostatic urethra, with part of the bladder, laid open from above, x. Trigone. 2. Opening of ureter. 3. Uvula vesicae. 4. Lateral lobe of prostate. 5. Opening of sinus pocularis. 6. Veru montanum. 7. Prostatic sinus and opening of prostatic ducts. 8. Aperture of ejaculatory duct. 9. Membranous part of urethra. 10. Crus penis. ir.Cowper's gland, and commence- ment of its duct. 12. Upper surface of bulb. 13. Com- mencement of bulbous portion of urethra. 14. Section of crus penis. 15. En- trance of duct of Cowper’s gland. 16. Spongy part of urethra. each side of the veru, a shallow fossa, the prostatic sinus, in which are seen the numerous openings (15 to 20) of the prostatic ducts. The veru montanum is most prominent in the centre ; and im- mediately in front of the prominent part is the opening of a small caecal sac, the sinus pocularis, or vesicula prostatica (uterus mas- culinus). This sac is the homologue of the uterus ; it is nearly half an inch in length, extends back beneath the third lobe of the pros- tate, and by its approach to the surface contributes to the prominence URETHRA. 777 of tlie veru montanum. Its walls, of a yellowish-white colour, are composed of areolar and elastic tissue, mingled towards its fundus with unstriped muscular tibre, and it is lined within by a laminated epithelium, the surface layer being formed of flattened cells. The ejaculatory ducts take their course forward in the walls of the sinus pocularis, and terminate close to its aperture by slit-like open- ings. The veru montanum contains erectile and muscular tissue, and it is believed that its distension may prevent the semen passing back into the bladder during emission. The membranous portion is the narrowest and most fixed part of the canal; it measures about one-fifth of an inch in diameter, and is about three-quarters of an inch in length along its lower wall, and half an inch on its upper. It extends from the apex of the pros- tate gland to the bulb of the corpus spongiosum, and passes through the triangular ligament. Its coats are—the mucous membrane, cir- cular muscular coat, and compressor urethrae muscle. The sub- mucous tissue is richly supplied with vessels, and much resembles erectile tissue. The spongy portion, about six inches in length, forms the rest of the extent of the canal, and is lodged in the corpus spongiosum from its commencement at the triangular ligament to the meatus urinarius. It is narrowest in the body, and dilated at each ex- tremity, posteriorly in the bulb, where it is named the bulbous portion, and anteriorly in the glans penis, where it forms the fossa, navicularis. The meatus urinarius is the most constricted part of the canal; so that a catheter, which will enter that opening, may be passed freely through the whole extent of a normal urethra. Opening into the bulbous portion are two small excretory ducts about an inch in length, which may be traced backwards, between the coats of the urethra and the bulb, to the under part of the mem- branous portion behind the triangular ligament, where they originate in two small, lobulated, and somewhat compressed glands, of about the size of peas, Cowper's glands. These glands are enclosed in a thin capsule, their glandular structure being held together by areolar tissue and smooth muscular fibre ; smooth muscular fibre is also found as a longitudinal layer, around their excretory ducts. They are situated immediately beneath the membranous portion of the urethra, and are enclosed by the lower segment of the compressor urethrae muscle, so as to be subject to muscular com- pression. On the whole internal surface of the spongy portion of the urethra, and especially along its lower surface, are numerous small openings of lacunae, and the apertures of mucous glands situated in the submucous areolar tissue (glands of Littre). The openings of the lacunae are directed forwards, and are liable occa- sionally to intercept the point of a small catheter in its passage to the bladder. At about an inch and a half from the opening of the meatus, in the upper wall of the urethra, one of the lacunae is generally found much larger than the rest, and is named the lacuna magna. 778 MALE ORGANS OF GENERATION. The urethral canal is closed, except during the passage of urine or semen, the closure resulting in the mucous membrane being thrown into longitudinal folds ; the lumen in this condition forms a transverse slit, but at the meatus the slit is vertical. TESTICLES. The testicles are two small glandular organs suspended from the abdomen by the spermatic cords, and enclosed in an external tegu- mentary covering, the scrotum. The SCROTUM is distinguished into two lateral halves or hemi- spheres by a raphe, which is continued anteriorly along the under surface of the penis, and posteriorly along the middle line of the perineum to the anus. Of these two lateral portions the left Is somewhat longer than the right, and corresponds with the greater length of the spermatic cord on the left side. The scrotum is composed of two layers, integument, and a proper covering, the dartos : the integument is thin, devoid of fat, semi- transparent, possesses numerous large sebaceous and sudoriparous glands, is beset with hairs which issue obliquely from the skin, and have prominent roots, and has usually a dark colour from the presence of pigment in the epidermis. The tunica dartos is a thin reddish layer composed of unstriped muscular tissue ; it forms the proper tunic of the scrotum, and sends inwards a septum, septum scroti, which divides the cavity into two sacs for the two tes- ticles. The dartos is continuous around the base of the scrotum with the common superficial fascia of the abdomen and perineum, and in an attenuated form is prolonged upon the penis to the prepuce. The SPERMATIC CORD is the medium of communication between the testicle and the interior of the abdomen ; and is composed of arteries, veins, lymphatics, nerves, the excretory duct of the testicle, and investing tunics. It commences at the internal abdominal ring, where the vessels of which it is composed converge, and passes obliquely along the spermatic canal ; the cord then escapes at the external abdominal ring, and descends through the scrotum to the posterior border of the testicle. The left cord is somewhat longer than the right, and permits the left testicle to reach a lower level than its fellow. The arteries of the spermatic cord are—the spermatic artery from the aorta; the deferential artery, accompanying the vas deferens, from the superior vesical; and the cremasteric, from the epigastric artery. The spermatic veins form a plexus which constitutes the chief bulk of the cord ; they are provided with valves at short in- tervals, and the smaller veins have a peculiar tendril like arrange- ment, which has obtained for them the name of pampiniform plexus (spermatic plexus). The lymphatics are of large size, and terminate in the lumbar glands. The nerves are the spermatic plexus of the sympathetic, which is derived from the aortic and renal plexus, the TESTICLES. 779 genital branch of the genito-crural nerve, and the inguinal branch of the ilio-inguinal. The vas deferens, the excretory duct of the testicle, is situated along the posterior border of the cord, where it may be distin- guished by the hard and cordy sensation which it communicates to the fingers. It is about a line or a line and a half in thickness ; its parietes are thick and tough, and its canal from one-fourth to one-third the diameter of the entire duct. In structure it is com- posed of three coats—an external or fibrous coat, which is thin ; a middle or muscular coat, which is remarkable for its thickness, and consists of three layers of smooth muscular fibre, namely, ex- ternal longitudinal, middle circular, and internal longitudinal ; and an internal or mucous coat, the mucous membrane being pale in colour, disposed in longitudinal pleats, and coated with a columnar epithelium, composed of cells containing yellowish pigment granules. In the dilated portion, near its termination (ampulla), it presents a reticular appearance, like that of the vesiculse seminales. The coverings of the spermatic cord are—the spermatic fascia, cremaster muscle, and fascia propria. The spermatic fascia is a prolongation of the intercolumnar fascia, derived from the borders of the external abdominal ring during the descent of the testicle in the foetus. The cremasteric covering, erythroid, is the thin mus- cular expansion formed by the spreading out of the fibres of the cremaster, which is likewise carried down by the testicle during its descent. The fascia propria is a continuation of the infundibuliform process from the transversalis fascia, which immediately invests the vessels of the cord, and is also obtained during the descent of the testicle. The TESTICLE is a small oblong and rounded gland, about an inch and a half in length, somewhat compressed at the sides and behind, and suspended in the cavity of the scrotum by the spermatic cord. Its position in the scrotum is oblique, so that the upper extremity is directed upwards and forwards, and a little outwards ; the lower, downwards and backwards, and a little inwards ; the convex border looks forwards and downwards, and the flattened border to which the cord is attached, backwards and upwards. Lying against its outer and posterior border is a flattened body which follows the course of the testicle, and extends from its upper to its lower ex- tremity ; this body is named, from its relation to the testis, epi- didymis (eVt, upon ; St'Sugos, the testicle) ; it is divided into a central part or body, an upper extremity, head or globus major, and a lower extremity, tail or globus minor. The globus major is situated against the upper end of the testicle, to which it is closely adherent; the globus minor is placed at its lower end, is attached to the testicle by areolar tissue, and curves upwards, to become continuous with the vas deferens. The testicle is invested by three tunics—tunica vaginalis, tunica albuginea, and tunica vasculosa, and is connected to the inner surface of the dartos by a large quantity of extremely loose areolar tissue, 780 MALE ORGANS OF GENERATION. in which fat is never deposited, but which is very susceptible of serous infiltration. The tunica vaginalis is a pouch of serous membrane derived from the peritoneum in the descent of the testicle, and afterwards obliterated from the abdomen to within a short distance of the gland. It is a shut sac, investing the organ, visceral portion, and then reflected so as to form a bag around its circumference, parietal portion. On the outer side it forms a shallow pouch called digital fossa, between the testicle and the body of the epididymis. The visceral portion, tunica vaginalis propria, covers the surface of the tunica albuginea, and surrounds the epididymis, connecting it to the testicle by means of a duplicature. The parietal portion, tunica vaginalis communis, is attached by its external surface, through the medium of a quantity of loose areolar tissue, to the inner surface of Fig. 479.—Transverse section of the testicle. 1. Cavity of the tunica vaginalis ; the most external layer is the parietal layer; and that in contact with the organ, the visceral layer. 2. Tunica albuginea. 3. Medias- tinum testis giving off numerous fibrous cords in a radiated direction to the internal surface of the tunica albuginea. The cut extremities of the vessels below- the figure belong to the rete testis; and those above to the arteries and veins of the organ. 4. Tunica vasculosa. 5. One of the lobules, consisting of the convolutions of the tubuli seininiferi, and terminating by a single duct, the vas rectum. Corresponding lob- ules are seen between the other fibrous cords of the mediastinum. 6. Section of the epididymis. the dartos. Between the two layers is the smooth surface of the shut sac, moistened by its secretion. At the upper part of the testicle and in front of the globus major of the epididymis one or two small pedunculated bodies are commonly observed ; they are described as the hydatids of Morgagni, and are composed of connective tissue and blood-vessels with a covering of tunica vaginalis. The largest of these is regarded as the remains of a foetal structure called the duct of Muller. The tunica albuginea is a thick areolo-fibrous membrane, of a bluish-white colour, and the proper tunic of the testicle. It is adherent externally to the tunica vaginalis propria, and, from the union of a serous with a fibrous membrane, is regarded as a fibro- serous membrane, like the dura mater and pericardium. After surrounding the testicle, the tunica albuginea is reflected from its posterior border into the interior of the gland, and forms a project- ing longitudinal ridge, the mediastinum testis (corpus Highmori- anum), from which numerous fibrous cords (trabeculae, septula) are given off, to be inserted into the inner surface of the tunic. The mediastinum contains the blood-vessels and ducts in their passage TESTICLES. 781 into the substance of the organ. If a transverse section of the testicle be made, and the surface of the mediastinum examined, it will be observed that the blood-vessels of the substance of the organ are situated near the posterior border of the mediastinum, while the divided ducts of the rete testis occupy a place nearer the anterior margin. The whole internal surface of the tunica albuginea is covered by a plexus of minute blood-vessels, which also extends on to the septa derived from the mediastinum ; this layer is sometimes described as the tunica vasculosa. The substance of the testicle consists of numerous conical flattened lobules, the bases being directed towards the surface of the organ, and the apices towards the mediastinum. Krause found between four and five hundred of these lobules in a single testicle. Each lobule is invested by a distinct sheath formed of two layers, one being derived from the tunica vasculosa, the other from the tunica albuginea. The lobule is composed of from one to three minute tubuli, tubuli seminiferi,* exceedingly con- voluted, anastomosing fre- quently with each other near their extremities, terminating in loops or in free csecal ends, and of the same diameter, TJ lgey ai'e supported by a peculiar tissue containing a large quantity of nuclear and molecular elements, and in which there are acunar spaces lined by a flattened epithelium, these spaces being the radicles of the lymphatics. The epididymis is formed by the convolutions of the excretorv seminal ducts, externally to the testis, and previously to their termination in the vas deferens. The more numerous convolutions and the aggregation of the coni vasculosi at the upper end of the organ constitute the globus major; the continuation of the convo- lutions downwards is the body; and the smaller number of con- volutions of the single tube at the lower extremity, the globus minor. he tubuli are connected together by filamentous areolar tissue, and bands of fibrous tissue. Pig. 481.--Section of the tubuli seminiferi of a rat. a. Tubuli in which the spermatozoa are commencing to form. b. Spermatozoa more fully developed, c. Spermatozoa fully developed. (E. A. Schafer.) TESTICLES. 783 A small convoluted duct, of variable length, is generally con- nected with the duct of the epididymis, just at the commencement of the vas deferens. This is the vasculum aberrans of Haller ; it is attached to the epididymis by the areolar tissue in which that body is enveloped. Sometimes it becomes dilated towards its extremity, but more frequently retains the same diameter through- out. The rete testis is lined by a single layer of squamous cells. The lining cells of the vasa efferentia and upper part of the epididymis are columnar or prismatic in form, and are ciliated ; in the lower part of the epididymis the cilia disappear. The walls of these canals are of considerable thickness, and contain unstriped muscular fibre arranged for the most part in a circular manner. In front of the spermatic cord, and in contact with the globus major of the epididymis, is a minute irregular structure, which, on microscopic examination, is found to be tubular. It is the remains of the Wolffian body, and is called the parepididymis or organ of Giraldes. The vas deferens may be traced upwards, from the globus minor of the epididymis along the posterior part of the spermatic cord, and along the spermatic canal to the internal abdominal ring. From the ring it is reflected inwards to the side of the fundus of the bladder, and descends along its posterior surface, crossing the ureter, to the inner border of the vesicula seminalis. In the latter situation it becomes somewhat larger in size and sacculated (forming an ampulla), and terminates at the base of the prostate gland, by uniting with the duct of the vesicula seminalis, and constituting the ejaculatory duct. The ejaculatory duct, which is thus formed by the junction of the duct of the vesicula seminalis with the vas deferens, passes forwards in the outer wall of the sinus pocularis, and terminates by a slit-like opening by the side of the aperture of the sinus. The TESTICLES IN THE EMBRYO are situated in the lumbar regions, immediately in front of and somewhat below the kidneys. They have, connected with them interiorly, a peculiar structure, which assists in their descent, and is called the gubernaculum testis. The gubernaculum is a soft and conical cord, composed of areolar tissue, containing in its areola: a gelatiniform fluid. In the abdomen it lies in front of the psoas muscle, and passes along the spermatic canal, which it serves to distend for the passage of the testis. It is attached by its superior and larger extremity to the lower end of the testis and epididymis, and by the inferior extremity to the bottom of the scrotum. The gubernaculum is surrounded by a thin layer of muscular fibres, the cremaster, which passes upwards upon this body to be attached to the testis. Interiorly the muscular fibres divide into three processes, which are thus attached : the external and broadest is connected to Poupart’s ligament in the inguinal canal; the middle forms a lengthened band, which escapes at the external abdominal ring, and descends to the bottom of the 784 DESCENT OF THE TESTICLE. scrotum, where it joins the dartos ; the internal passes in the direc- tion inwards, and has a firm attachment to the os pubis and sheath of the rectus muscle. Besides these a number of muscular fibres are reflected from the internal oblique on the front of the guberna- culum. The descent of the testicle is gradual and progressive. Between the fifth and sixth month it lias reached the lower part of the psoas muscle, and, during the seventh, makes its way through the spermatic canal, and descends into the scrotum. While situated in the lumbar region, the testicle and gubernaculum are placed behind the peritoneum by which they are invested upon their anterior surface and sides, forming a mesorchium. As they de- illustrating the descent of the tes- ticle. i. Testicle. 2. Epididymis. 3, 3. Peritoneum. 4. Pouch formed a- round the testicle by the peritone- um, tlie future cavity of the tuni- ca vaginalis. 5. Pubic portion of the cremaster at- tached to the lower part of the testicle. 6. Portion of the to Poupart’s ligament. The mode of eversion of the cremaster is shown by These lines. 7. Gubernaculum attached to the bottom of the scrotum 8 8 Cavity of the scrotum. Fi(i. 483.-111 this figure the testicle has completed its descent. The gubemaeulum is shortened to its utmost, and the cremaster completely everted. The pouch of peritoneum above the testicle is compressed so as to form a tubular canal, 2. A dotted line marks the point at which the tunica vaginalis will terminate supe- riorly ; and the figure 2 its cavity. 3. Peritoneal cavity. scend, the investing peritoneum is carried downwards with the tes- ticle into the scrotum, forming a lengthened pouch, which by its upper extremity opens into the cavity of the peritoneum. The upper part of this pouch, being compressed by the spermatic canal, is gradually obliterated, the obliteration extending downwards along the spermatic cord nearly to the testicle. That portion of the peritoneum immediately surrounding the testicle is, by the above process, cut off from its continuity with the peritoneum, and is termed the tunica vaginalis. In its descent the testicle receives cer- tain structures from the different layers of the abdominal wall; these have been enumerated in connection with the description of inguinal hernia (p. 296), the coverings being exactly the same as those of the oblique form of that affection. FEMALE BLADDER AND URETHRA. 785 FEMALE PELVIS. The peculiarities in form of the female pelvis have already been examined with the anatomy of the bones (p. 160). Its lining boun- daries are the same as those of the male. The contents are the bladder, vagina, uterus with its appendages, and rectum. Some por- tion of the small intestine also occupies the upper part of its cavity. The bladder is in relation with the pubes in front, with the Fig. 484.—Side view of the viscera of the female pelvis. 1. Symphysis pubis. 2. Abdominal pari- etes. 3. Collection of fat, forming the mons Veneris. 4. Urinary bladder. 5. Entrance of left ureter. 6. Urethra. 7. Meatus urina- rius. 8. Clitoris, with its prepuce divided through the middle. 9. Left nympha. 10. Left labium majus. 11. Meatus of the vagina, narrowed by the contraction of its sphincter. 12, 22. Canal of the vagina, on which the transverse rugae are apparent. 13. Vesico-vaginal wall. 14. Recto- vaginal wall. 15. Perineal body. 16. Os uteri. 17. Cervix. 18. Fundus uteri. The cavity of the uterus is seen along the centre of the organ. 19. Rectum, showing the disposition of its mucous mem- brane. 20. Anus. 21. Upper part of rectum, invested by peritoneum. 23. Uteio- vesical fold of peritoneum. The recto-vaginal fold is seen between the rectum and posterior wall of the vagina. 24. Reflection of peritoneum, from the apex of the bladder upon the urachus to the internal surface of the abdominal parietes. 25. Last lumbar vertebra. 26. Sacrum. 27. Coccyx. This view is diagrammatic, the vagina being shown dilated ; in the normal state the walls are.in loose contact, excepting at the upper part, where the canal has the os uteri projecting into it. uterus behind, from which it is usually separated by a convolution of small intestine, and with the neck of the uterus and vagina be- neath. The form of the female bladder corresponds with that of the pelvis, being broad from side to side, and often bulging more on one side than on the other. This is particularly evident after par- turition. The coats of the bladder are the same as those of the male. The urethra, about an inch and a half in length, is lodged in the upper and anterior wall of the vagina, in its course downwards and forwards, beneath the arch of the pubes, to the meatus urinarius. Skene has discovered in each lateral urethral wall a minute tubule about f to | of an inch in length, passing beneath the mucous mem- brane in the muscular wall of the urethra; these canals have been 786 VAGINA. named in honour of their discoverer Skene's txibules. The urethra is composed of three coats, mucous, submucous, and muscular ; the mucous coat is vascular, and disposed in longitudinal folds, and is continuous internally with the mucous membrane of the bladder and externally with that of the vulva. It is provided with a squamous epithelium, having a deep stratum of elongated cells, like the mucous membrane of the bladder, and near its extremity has, opening on its surface, the ducts of numerous racemose mucous glands, the glands of Littre. The submucous coat is loose, and provided with a con- siderable plexus of veins, and in its areolar tissue are situated the racemose mucous glands, which open into the urethra near its ter- mination. Tht' muscular coat consists of two layers, which are con- tinuous with the muscular structure of the bladder, the internal layer being longitudinal, and mingled with areolar and elastic tissue ; the external circular, and continuous with the middle layer of the mus- cular coat. The female urethra is remarkable for its distensibility, which is only restricted at the meatus by a ring of dense areolar tissue ; hence, in distending the urethra for surgical purposes, it is often necessary to divide the margin of the meatus with the knife. VAGINA. The vagina is a membranous canal, leading from the vulva to the uterus, and corresponding in direction with the axis of the outlet of the pelvis. It is constricted at its commencement, hut near the uterus becomes dilated, and is closed by the contact of the anterior with the posterior wall, so as to appear in sections as a mere longi- tudinal or transverse slit. Its length is variable ; but it is always longer on the posterior than on the anterior wall, the former being usually about five or six inches in length, the latter about four. It is attached to the cervix of the uterus, which latter projects into the upper extremity of the canal. Its upper fourth is covered pos- teriorly by the peritoneum, while anteriorly the peritoneum is re- flected from the cervix uteri without reaching so low as the vagina ; it is firmly connected to the bladder in front, and loosely to the rectum behind ; at the sides it receives the attachment of the posterior layer of the broad ligaments above, and that of the pelvic fascia and levatores ani below. Its close connection with the bladder occasionsthe prolapsus of that organ in cases of prolapsus uteri, while its looser con- nection with the rectum preserves the latter from a similar accident. Structure.—The vagina, about one line in thickness, is composed of three coats : external, fibrous ; middle, muscular ; and internal, mucous. The external or fibrous coat is thin and white, and consists of condensed areolar tissue, with an admixture of elastic fibres. It is firm around the upper part of the tube, and lax in- teriorly, and contains in its tissue, especially below, an abundant venous plexus. By its inner surface it is blended with the muscular coat without any distinct separation. The middle or muscular coat is composed of smooth muscular fibre, arranged in longitudinal and VAGINA AND UTERUS. 787 circular bundles, and intermingled with areolar tissue and a con- siderable plexus of veins. The internal or mucous coat is of a pale red colour, and disposed in nu- merous pleats or folds, column® rugarum ; which diverge trans- versely from a middle 1 ine, orraphe, situated on the anterior and posterior wrall of the vagina ; the rug® are most strongly developed on the an- terior wall, and near the entrance of the vagina, and are termed columns of the vagina. In inti- mate structure the mucous membrane consists of areolar and elastic tissue, to which its firmness and elasticity are due, and presents numerous conical papilke embedded in a squamous epi- thelium. The epi- thelium is thick and laminated, resem- bling that of the oesophagus, its upper- scales measuring about an dich in diameter; it is con- tinuous externally with the epithelium of the vulva, and terminates internally at about the middle of the cervix uteri. Opening on to the surface of the mucous membrane are numerous mucous follicles and glands ; they are especially plentiful in the upper smooth portion of the vagina and around the cervix uteri. Fig. 485.—Vertical mesial section of a nulliparous female, showing the normal position and relations of the pelvic organs. 1. Pubic symphysis. 2. Peritoneum. 3. Outer layer of bladder wall. 4. Inner layer. 5. Retro-pubic fat. 6. Clitoris. 7. Vena dorsalis clitoridis. 8. Transversus perinei muscle. 9. Circular muscular fibres of urethra. 10. Labium major. 11. Urethral orifice. 12. Nyinpha. 13. Longitudinal muscular fibres of urethra. 14. Deep circular fibres. 15. Orifice of vagina. 16. Perineal body. 17. External sphincter ani. 18. Internal sphincter. 19. Anus. 20. Hecto-vaginal fold of peritoneum. 21. Posterior part of internal sphincter ani. 22. External sphincter. 23. Vagina. 24. Anterior lip of os uteri. 25. Posterior lip of os. 26. Levator ani. 27. Sacrum. 28. Rectum. 29. Uterus. The uterus or womb is a flattened organ of a pyriform shape, having the base directed upwards and forwards, and the apex down- wards and backwards, in the line of the axis of the inlet of the pelvis, and forming a considerable angle with the course of the UTERUS. 788 UTERUS. vagina. Its position, however, varies very greatly with the varying conditions of the bladder and rectum ; when the bladder is empty the body of the uterus may be horizontal. It is convex on its posterior surface, and somewhat flattened in front; in the un- impregnated state it is about three inches in length, two in breadth across its broadest part, and one in thickness ; and is divisible into fundus, body, cervix, and os uteri. At the period of puberty the uterus weighs about one ounce and a half ; after parturition from two to three ounces ; and at the ninth month of utero-gestation from two to four pounds. The fundus and body are enclosed in a duplicature of perito- neum, which is connected with the sides of the pelvis, and forms a transverse septum between the bladder and rectum. The folds formed by this dupli- cature of peritoneum at each side of the organ are the broad ligaments. The cervix is the lowest portion of the uterus ; it is distinguished from the body by a well-marked constriction; around its cir- cumference is attached the upper end of the vagina, and at its extremity is an opening which is nearly round in the virgin, and transverse after parturition, the os uteri (os tincse), bounded before and behind by two labia ; the posterior labium being somewhat longer than the anterior, and somewhat less thick. The opening of the os uteri is of considerable size, and is named the os uteri externum : the canal then becomes narrowed, and at the upper end of the cervix is constricted into a smaller opening, the os internum. Beyond this point the canal of the cervix expands into the shallow triangular cavity of the uterus, the inferior angle corre- sponding with the os internum, and tin' two superior angles, which are funnel- shaped and represent the original bicornute condition of the organ, with the com- mencement of the Fallopian tubes. Structure.—The uterus is composed of three tunics : of an external or serous coat, derived from the peritoneum, which constitutes the duplicatures at each side of the organ called the broad ligaments ; of a middle or muscular coat, and of an internal or mucous membrane, which lines its interior, and is continuous on the one hand with the mucous lining of the Fallopian tubes, and on the other with that of the vagina. The peritoneum forms only a partial covering to the front of the Fir,. 486.—Median vertical suc- tion through uterus and upper part of vagina. a. Anteiior wall of vagina, p. Posterior wall. STRUCTURE OF THE UTERUS. 789 uterus, extending from the fundus to about the lower third, where it is reflected on to the bladder, forming the redo-vesical fold. O11 the posterior aspect it not only covers the whole surface of the uterus, but passes on to the posterior vaginal wall for rather more than an inch, and from thence is continued to the rectum, forming the recto-vaginal pouch or space of Douglas. In the unimpregnated state the muscular coat is exceedingly dense in texture, offers resistance to section with the scalpel, and appears to be composed of whitish fibres inextricably interlaced and mingled with blood-vessels. In the impregnated uterus the fibres are of large size, distinct, and separable into three layers : external, which are longitudinal and transverse, the former constituting a thin plane on the anterior and posterior surface and fundus of the organ, the latter being prolonged outwards on the Fallopian tubes, and into the round and ovarian ligaments ; middle, a thick layer Fig. 487.—Uterus with its appendages viewed from the front. 1. Body of the uterus. 2. Fundus. 3. Cervix. 4. Os uteri. 5. Vagina; the figure is placed on the posterior raphe or columna, from which the transverse rugae are seen passing off at each side. 6, 6. Broad ligament of the uterus. 7. Convexity of the broad ligament formed by the ovary. 8, 8. Round ligaments of the uterus. 9, 9. Fallopian tubes. 10, 10. Fimbriated extremities of the Fallopian tubes ; on the left side the mouth of the tube is turned forwards in order to show its ostium abdominale. n. Ovary. 12. Utero-ovarian ligament. 13. Tubo-ovarian ligament, on which some small fimbria) are continued for a short distance. 14. Peritoneum of anterior surface of uterus. This membrane is removed at the left side, but on the right is continuous with the anterior layer of the broad ligament. consisting of fiat bundles of transverse, longitudinal, and oblique fibres, complexly interlaced, and traversed by a plexus of large veins, which give this portion of the substance of the uterus a spongy appearance ; and an internal layer of longitudinal fibres, which is thin and slender, and is disposed chiefly on the back of the fundus. The muscular tissue of the uterus is of the unstriped variety, and consists of long, nucleated, fibre cells, mixed with a con- siderable quantity of areolar tissue in which are many nucleated cells. The mucous membrane, of a whitish or pale red colour, is closely connected, or more correctly, is blended with the muscular coat; it is characterised by possessing a very thick layer of muscularis mucosae, a ciliated epithelium, and a number of tubular glands. 790 UTERUS. The muscidaris mucosal forms the greater part of the thickness of the uterine wall; the fibres form concentric rings in the fundus, round the openings of the Fallopian tubes, and in the cervix form the sphincters of the external and internal os uteri. In the cervix uteri the raucous membrane is somewhat thicker than in the fundus, and on the anterior and posterior surface of its canal is disposed in folds, plicae palmatae, which have received the name of arbor vitae uterina. In the lower part of the cervix, moreover, are found fili- form papillae, invested by a ciliated epithelium. The mucous glands of the uterus, or uterine gland*, are minute follicles corresponding in length with the thickness of the mucous membrane, very numerous, sometimes simple, sometimes bifid, and sometimes spirally twisted. Their structure resembles other mucous glands, namely, a basement membrane, an epithelium of prismatic cells, with their broad bases and nuclei towards the basement mem- brane, and their narrow ends towards the lumen of the gland. The cells near the mouth of the follicle are surmounted by cilia, the deeper ones being devoid of them. The glands become much en- larged during pregnancy. In the cervix uteri, between the plicm palmatae, are found other mucous follicles which secrete the peculiar transparent mucus of that region. It is these follicles in an imper- forate state which constitute the small transparent vesicles termed ovula Nabothi, seen in the canal of the cervix around the os uteri, and sometimes in its cavity. Vessels and Nerves.—The arteries of the uterus are—the uterine from the internal iliac, and the ovarian from the aorta ; they ramify through the muscular and mucous coat, forming a plexus of larger vessels in the deep portion of the latter, and of smaller vessels in its superficial portion ; from the smaller vessels are given off the capil- laries, which constitute a fine plexus around the glands and a coarse plexus at the surface, the blood from the latter passing into the veins. The veins take the course of the arteries, and terminate in the venous plexus situated on each side of the body of the uterus. In the im- pregnated womb, the veins are so much dilated as to deserve the name of sinuses; they are thin in structure, and devoid of valves, and their great number in the muscular coat gives a spongy appear- ance to the walls of the pregnant uterus. The lymphatics are numerous, the deep commencing in the mucous membrane, the superficial taking their course in the subserous tissue ; they follow the direction of the blood-vessels, and terminate in the peivic and lumbar glands. The nerves of the uterus are derived from the hypogastric and spermatic plexuses, and from the sacral plexus. They form a very elaborate plexus, in the midst of which numerous ganglia are found. Of these latter the chief are—one, called the hypogastric or cervical ganglion, which is situated at the side of the cervix just behind the ureter ; another, spermatic ganglion, which supplies the fundus uteri ; and a number of smaller ones, called posterior and anterior subperi- toneal, vesical, and vaginal ganglia. FALLOPIAN TUBES. 791 The nerves of the uterus all increase in size during pregnancy, and again decrease after parturition. Appendages of the Uterus. The appendages of the uterus are enclosed by the lateral duplica- tors of peritoneum called the broad ligaments. They are the Fallopian tubes and ovaries. The FALLOPIAN TUBES, or oviducts, are situated in the upper border of the broad ligaments, and are connected with the superior angles of the uterus. They are somewhat trumpet-shaped, being smaller at the uterine than at the free extremity. The narrow inner extremity has been named by Henle the isthmus, and the wider outer half the ampulla. Each tube is about four inches in length, and more or less flexuous in its course. The canal of the Fallopian tube is exceedingly minute ; its inner extremity opens by means of the ostium uterinum into the upper angle of the cavity of the uterus, and the opposite end into the cavity of the peritoneum. The free or expanded extremity of the Fallopian tube presents a double and sometimes a triple series of small processes or fringes which surround the margin of the trum- pet or funnel-shaped opening, the ostium abdominale. This fringe- like appendage to the end of the tube has gained for it the appella- tion of the fimbriated extremity (morsus diaboli). A short liga- mentous cord proceeds from the fimbriated extremity to be attached to the distal end of the ovary. Structure.—The Fallopian tube is composed of three tunics—an external and serous investment derived from the peritoneum ; a middle or muscular coat, consist- ing of circular (internal) and longitudinal (external) fibres, continuous with those of the uterus ; and an internal or lining mucous mem- brane, which is continuous on the one hand with the mucous mem- brane of the uterus, and at the opposite extremity with the peritoneum. Fig. 488.—Transverse section of Fallopian tube of a nulliparous female, showing three tubes separated by intertubular tissue. 1. Serous outer coat. 2. Inter- stitial connective tissue. 3. Muscular coat, consisting chiefly of circular fibres. 4. Mucous membrane thrown into ir- regular folds. 5, 5. Lumen of tubes. At 6 the mucous membrane has been stripped off in making the section.— From a preparation by Dr. Milroy of Kilwinning. 792 OVARIES. The fibres of smooth muscle are mingled, as in the uterus, with imma- ture nucleated areolar tissue. The mucous membrane is thin, pale, and soft, without villi or glands, and disposed in longitudinal pleats. It is invested by an epithelium consisting of a single layer of conical or filiform ciliated cells, the direction of the vibrations of the cilia being towards the cavity of the uterus. The inner surface of the fimbria is covered with ciliated epithelium, and this is continued for a short distance on to the outer surface, but soon passes into the squamous form, similar in character to the cells covering the peri- toneum. In some instances there are two or more canals, as shown in Fig. 488 ; as they are surrounded by a common investment, it is not probable that this appearance is produced by great convolution of the tube, and the consequent appearance of several parts of the tube in the same section. If the broad ligament of the uterus be held up to the light, a few scattered tubules will be seen between the ovary and Fallopian tube. These constitute the par ovarium or organ of Rosenmiiller. They are lined with epithelium, and are closed at their ovarian extremity, but communicate at the other end with an imperfect duct, which in the sow and some other animals forms the duct of Gaertner. The par ovarium is developed along with the Wolfiian body, and seems to be the representative in the female of the coni vasculosi of the testicle of the male. The OVARIES (testis muliebres) are two oblong, flattened, and oval bodies, of a whitish colour and uneven surface, dependent from the posterior layer of peritoneum of the broad ligaments. They are. connected to the upper angles of the uterus at each side by means of a rounded cord, con- sisting of fibrous tissue, and a few muscular fibres derived from the uterus, the ligament of the ovary. By the opposite extremity they are connected by an- other and a shorter ligament to the fim- briated aperture of the Fallopian tube, tubo- ovarian ligament. Structure. — The ovary is composed of a spongy fibrous stroma of a greyish-red colour, containing a number of small cells traversed by blood - vessels, and is covered by a serous membrane which in the early history of the. organ was evidently a continuation of the peritoneum. The Fio. 489.—The ovary, a, a. Stroma. 6, b, b. Small Graafian vesicles, c. A mature vesicle, <1. A fresh corpus luteum, with thick lining *. e. An old corpus luteum. g. Veins. STRUCTURE OF THE OVARIES. 793 cells of this outer membrane differ from those of the peritoneum in being columnar or prismatic, and in their giving to the surface a dull appearance instead of the smooth glistening character usually distin- guishing serous mem- branes ; the cells have received the name of germ epithelium because they originate the ova. Be- neath this membrane is a layer of condensed stroma, having a white appearance, and called from its supposed resem- blance to one of the coats of the testicle the tunica albuginea. The deep part of the stroma is formed of fibrous tissue containing a large number of nuclei and some elastic tissue ; the fibres radiate from the attached border or hilus towards the circumference in small bundles. Under- neath the capsule, the tissue of the organ is crowded with closely set vesicles, forming an early condition of the char- acteristic structures of the ovary, the Graafian vesi- cles ; deeper in, the vesicles are less numerous but much larger. The ovisac or Graafian vesicle is a vesicle consist- ing of an external mem- brane and fluid contents. The membrane is com- posed of an outer coat formed by the condensa- tion of the stroma, and sometimes named the tunica fibrosa, a base- ment membrane and an internal lining or epithelium. The epithelium consists of round or polygonal cells with large nuclei, and a greater or less number Pig. 490.—Section of ovary, a. Germ epithelium. 6. Ovarian tube, or string of ovigerms. c, c, c. Early vesicles, cl. A more mature vesicle, e. Ovum and discus proligerus. /. A second ovum in the same vesicle, g. Tunica fibrosa of vesicle, h. Inner coat of the vesicle, i. Epithelial lining (tunica granulosa). 1. Blood-vessel, cut across, m. Section of tubes of par ovarium, y. Involuted portion of germ epithelium of surface. 794 OVAR1ES. of fatty granules; the cells quickly lose their definition after death, and then the epithelium assumes the appearance which has gained for it the name of membrana granulosa, namely, a granular layer with numerous nuclei. The membrana granulosa forms a uniform lining to the ovisac, excepting on the side nearest the surface of the ovary, where the cells are accumulated into a small eminence, termed discus proligerus or germinal eminence. This germinal eminence contains a minute globular nucleated vesicle, the ovum. The fluid contents of the ovisac, liquor folliculi, are a clear yellowish fluid, and a few free albuminous cells detached from the membrana granulosa. The Graafian vesicles are very small in the outer part of the ovary, but are there so numerous as to give a graimlar character distinct from that of the rest of the organ ; hence it is defined as the cortical portion. In the deeper portions they are less numerous but larger and more mature, and as they increase in size they displace the cells of the cortical portion in order to reach the surface of the organ. Ovum.—The ovum, measuring in its mature state about , I of an inch in diameter, is a globular vesicle consisting of a cell mem- brane, the vitelline membrane, a yelk or vitellus, and a vesicular nucleated nucleus, the vesicular nucleus being the germinal vesicle, and the nucleolus the germinal spot. The cell membrane is clear and transparent, and has received the name of zona pellucida; with high magnifying powers, it is, however, possible to make out fine stria) passing radially through the membrane, and it is for this reason named the zona striata or striate membrane. The yelk, yellowish and viscid, consists of protoplasm filled with granules and nuclei, and traversed by an extremely fine reticulum. The germinal vesicle measures about -gfo inch, and consists of a nuclear network supporting nucleoplasm. As the ovisac attains maturity, it approaches nearer and nearer the capsule of the ovary, and pressing against the capsule renders it so thin that moderate pressure, such as that made by the fibriated extremity of the Fallopian tube, causes the protrusion and rupture both of the ovisac and the capsule of the ovary. By this rupture the ovum is expelled, carrying with it the germinal eminence and part of the membrana granulosa, which in its new relation is termed the germinal disc, discus proligerus. The ovisac, now emptied of its contents, is quickly filled with a sanguineous fluid, resulting from the tearing of its vessels, the internal portion of the tunica fibrosa becomes thickened and plicated, and converted into a yellow vascular tissue, while the external layer of the tunic retains its character of a white fibrous membrane. This is the corpus luteum, a yellowish mass with fast-diminishing cavity, plicated structure, vascular, and enclosed in a thin fibrous layer. It retains these characters up to the second or third month of pregnancy, and then slowly diminishes in size, being gradually lost some months after parturition is complete, or reduced to a small whitish or dark coloured mass. The corpora lutea, which are independent of preg- ROUND LIGAMENTS. 795 nancy, false corpora lutea, disappear in the course of one or two months, and leave behind them a scarcely perceptible trace of tlieir existence. Formation of Ova.—The ova are formed from the germ epithe- lium on the surface of the ovary, the cells becoming enlarged and penetrating into the substance of the ovum as shown at y, Fig. 490. After passing downwards for a short distance they lose their surface connection, and become enveloped by layers of condensed stroma constituting the walls of the Graafian vesicles ; the germ cell thus comes to form the ovum, its nucleus the germinal vesicle, and a nucleolus which soon appears in the centre of the nucleus the germinal spot. The cells of the membrana granulosa are the pro- duct of the nuclei of the fibro-nuclear tissue forming the stroma. Vessels and Nerves.—The arteries of the ovaries are branches of the uterine and ovarian. The arteries enter the ovary along its inferior border by numerous minute trunks, which pass in a serpen- tine course through its stroma, to be distributed chiefly to the walls of the ovisacs, forming an exterior coarse and interior fine capillary plexus. The veins constitute an ovarian plexus, which terminates in the uterine plexus. The lymphatics, few in number, terminate in the pelvic and lumbar glands. The nerves are derived from the spermatic plexus, and take the course of the arteries. The ROUND LIGAMENTS are two musculo-fibrous cords between four and five inches long, situated within the layers of the broad ligaments, and extending from the upper angles of the uterus and along the inguinal canals to the mons Veneris, in which they are lost. They are composed of smooth muscular fibre and areolar tissue, but towards the internal abdominal rings, have also numerous fasciculi of striated muscular fibres. The round ligaments are accompanied by a small artery, by several filaments of the spermatic plexus of nerves, by a plexus of veins, and by a process of the peritoneum which represents the serous membrane investing the spermatic cord in the male. In the young subject, this process extends for a short distance along the spermatic canal, and is deno- minated the canal of Nuck : it is sometimes pervious in the adult. The round ligaments serve to retain the uterus in position in the pelvis, and, during utero-gestation, to draw the anterior surface of the organ against the abdominal parietes. EXTERNAL ORGANS OF GENERATION. The female organs of generation are divisible into internal and external; the internal are contained within the pelvis, and have been already described ; they are—the vagina, uterus, ovaries, and Fallopian tubes. The external organs are the mons Veneris, labia majora, labia minora, clitoris, meatus urinarius, and opening of the vagina. The mons Veneris is the eminence of integument, situated on 796 FEMALE ORGANS OF GENERATION. the front of the pubes. Its areolar tissue is loaded with adipose substance, and the surface covered with hairs. The labia majora are two large longitudinal folds of integument containing areolar tissue, fat, and a tissue resembling the dartos. They enclose an elliptical fissure, the common urino-sexual opening or vulva. The vulva receives the inferior opening of the urethra and vagina, and is bounded anteriorly by the anterior commissure, and posteriorly by the posterior commissure. Stretching across the posterior commissure is a small transverse fold, the frcenulum Idbiorum or fourchette, which is ruptured during parturition ; and immediately within this fold a small cavity, the fossa navicularis. The external surface of the labia is covered with hairs; the inner surface is smooth, and lined by mucous membrane, which contains a number of large sebaceous glands, and is covered by a thin cuticular epithelium. The mass of tissue intervening between the posterior commissure and anus is known as the perineal body ; superficially it is covered by skin, and is generally spoken of by the accoucheur as “ the ‘perineum.” In median sections of the pel vic viscera it is seen to lie of triangular form (Fig. 485) with its base directed outwards and its apex inwards and backwards ; it is formed of the interwoven fibres of the sphincter ani and sphincter vaginae, with a large quantity of fat, and fibrous tissue and elastic tissue. The labia minora, or nyrn- phae, are two smaller folds, situated within the labia majora. Superiorly they are divided into two processes, which surround the glans clitoridis, the superior fold forming the prseputium clitoridis, the inferior its fraenu- lum. Inferiorly, they diminish gradually in size, and are lost on the sides of the opening of the vagina. The nymph* consist of mucous membrane, covered by a thin cuticular epithelium. They are provided with a number of sebaceous glands, and contain, in their interior, a plexus of blood-vessels. The clitoris is a small elon- gated organ situated in front of the pubes, and supported by a suspensory ligament. It is formed by a small body, analogous to the corpus cavernosum penis, and, like it, arises from the ramus of the os pubis and ischium at each side by two crura. At the extremity of the clitoris is a small accumulation of erectile tissue which is highly sensitive, and is termed the glans. Fio. 491.—External organs of generation of the female. 1. Preeputium clitoridis. 2. Clitoris. 3. Frenulum clitoridis. 4. Labium minor (Nympha). 5. Meatus urinarius. 6.0peningofDuvernay’sgland. 7. Hymen. 8. Fonrchette. 9. Posterior commissure. 10. Orifice of vagina. 11. Skene’s tubule opening into meatus. VESTIBULE OF THE VAGINA. Tlie corpus eavernosum clitoridis, like that of the penis, is composed of erectile tissue enclosed in a dense layer of fibrous membrane, and is susceptible of erection. Like the penis, also, it is provided with two small muscles, the erectores clitoridis. At about an inch behind the clitoris, is the entrance of the vagina, an elliptical opening, marked by a prominent margin. The entrance to the vagina is closed in the virgin by a duplieature of mucous membrane of a semilunar form, which is stretched across the opening ; this is the hymen. Sometimes the membrane forms a complete septum, and gives rise to inconvenience by preventing the escape of the menstrual effusion. It is then called an imper- forate hymen. The hymen must not be considered a necessary accompaniment of virginity, for its existence is uncertain. When present, it assumes a variety of appearances ; it may be a mem- branous fringe, with round opening in the centre ; or a semilunar fold, leaving an opening in front ; or a transverse septum, having an opening both in front and behind ; or a vertical band with an opening at each side. The rupture of the hymen, or its rudimentary existence, gives rise to the appearance of a fringe of papillae around the opening of the vagina ; these are called carunculae myrtiformes. The triangular smooth surface between the clitoris and the en- trance of the vagina, which is bounded at each side by the upper portions of the nymphse, is the vestibule. At the posterior part of the vestibule and near the margin of the vagina is the opening of the urethra, the meatus urinarius ; and around the meatus an elevation of the mucous membrane formed by the aggregation of numerous mucous glands. This prominence serves as a guide to finding the meatus in the operation of in- troducing the female catheter. Beneath the vestibule at each side, and extending from the clitoris to the side of the vagina, are two oblong or pyriform bodies, consisting of erectile tissue enclosed in a thin layer of fibrous membrane. These bodies are narrow above, broad and rounded below, and are termed by Kobelt, who considers them analogous to the bulb of the male urethra, the bulbi vestibuli. Behind these bodies and lying against the outer wall of the vagina are two small glands, analogous to Cowper’s glands in the male subject; they are the glands of Bar- tholin or Duvernay. Each gland opens by means of a long excre- tory duct on the inner side of the corresponding nympha. In front of the masses of erectile tissue forming the bulb of the vestibule is a smaller plexus of vessels continuous with those of that body behind and with the erectile tissue of the glans clitoridis in front ; it has been named by Kobelt the pars intermedia, and is supposed to cor- respond with that part of the corpus spongiosum penis lying in front of the bulb of the urethra in the male. The mucous membrane of the external organs, about a quarter of a line in thickness, is composed of areolar and elastic tissue, without fat, and rich in capillary vessels. It is furnished with 797 798 numerous papillae, which are large on the labia minora, smaller on the clitoris, and is invested by a squamous epithelium. On the internal surface of the labia majora, on the labia minora, and occasionally around the meatus urinarius and entrance of the vagina, there exist sebaceous glands ; while on the vestibule, around the meatus urinarius and around the entrance of the vagina, there is an abundance of racemose mucous glands, opening on the surface of the membrane by shorter and longer ducts. Vessels and Nerves.—The external organs of generation are abundantly supplied with arteries, chiefly by the internal pudic ; they terminate in a deep and superficial capillary plexus, as in other mucous membranes. Valentin has described helicine arteries in the clitoris. The veins returning the blood from the capillaries form a rich plexus, which is especially abundant in the bulbi vestibuli of Kobelt. The lymphatics are numerous, and communicate partly with the inguinal and partly with the pelvic glands. The nerves are derived partly from the hypogastric plexus and partly from the sacral plexus. MAMMARY GLANDS. The mammae are situated in the pectoral region, and are sepa- rated from the pectoralis major muscle by a thin layer of superficial fascia. Their base is somewhat elliptical, the long diameter corre- sponding with the direction of the fibres of the pectoralis major muscle ; and the left mamma is generally a little larger than the right. Near the centre of the convexity of each mamma is a small pro- minence of the integument, called the nipple (mammilla), which is surrounded by an areola having a coloured tint. In females of fair complexion before impregnation, the colour of the areola is a delicate pink ; after impregnation, it enlarges and assumes a brownish hue, which deepens in colour as pregnancy advances ; and after the birth of a child, the brownish tint continues through life. The areola is furnished with a number of sebaceous glands, which secrete a peculiar fatty substance for the protection of the delicate integument around the nipple. During suckling these glands increase in size, and have the appearance of small pimples, projecting from the skin. At this period they serve by their secre- tion to defend the nipple and areola from the excoriating action of the mouth of the infant. In structure, the mamma is a compound racemose or conglomerate gland, consisting of lobes, lobules, and gland-vesicles. The lobes, from 15 to 25 in number, have each a separate system of lobules and gland-vesicles, and a distinct excretory duct; hence, the mamma may be regarded as being composed of a number of separate glands, their excretory ducts converging to the nipple, and terminating at its extremity by distinct apertures. The lobes are irregular in size and form, flattened, and bounded by rounded angles ; they are made MAMMARY GLANDS. Up of smaller lobes or lobules, and the lobules of other lobules still more diminutive, the smallest lobules consisting of round or pyri- form gland-vesicles or alveoli. The gland-vesicles or alveoli, about of an inch in diameter, are composed of a basement membrane” lined with an epithelium, which changes in character with the varying conditions of the organ. When the gland is inactive, the alve- oli are very small, and the lining cells are small and granular. When active secretion is going on, the alve- oli are large and distended with fluid, the epithelial cells are flattened out against the mucous membrane and contain fat globules. The alveoli communicate with an excretory duct, and the excretory ducts of all the lobules unite to form a common excretory duct or canal for- each lobe, galactophorus duct. The duct, taking its course beneath the areola, dilates into an elongated sac or ampulla, and reaching the base of the mammilla, contracts in size and bends outwards into that process to terminate at its extremity by a small aperture. There are from 15 to 25 ducts in the nipple, a number corresponding with the number of lobes com- posing the gland. The gland-vesicles are held together by a dense white areolar tissue, which unites the lobules into lobes, and connects the dif- ferent lobes with each other, forming a covering for the whole, and being itself surrounded with adipose tissue. The galacto- phorus ducts are composed of areolar tissue, with longitudinal and circular elastic fibres, and, according to Henle, there is an indication of longitudinal smooth muscular fibre ; they are lined by columnar epithelium, passing into the squamous form near the openings on the nipple. The mammilla or nipple is covered by a thin epidermis, present- ing more or less pigment in its rete mucosum ; it possesses at the extremity a number of papillae, between which are the lactiferous openings, and it is composed internally of the ducts, united together and surrounded by areolar and smooth muscular tissue, the latter giving the nipple the faculty of erection and retraction. The inte- gument of the areola, besides possessing a coloured epidermis with numerous large sudoriparous and sebaceous glands, the latter associated with fine hairs, is also provided with a layer of smooth muscular fibre, which gives it a power of contraction. STRUCTURE OF THE MAMMARY GLAND. Fig. 492.—Gland-vesicles of the mam- mary gland during lactation, show- ing the lining cells and capillary vessels. 800 MAMMARY GLANDS. The secretion of milk is effected by the formation of oil- globules in the epithelial cells of the gland-vesicles ; the epithelial cells being perfected, are pushed outwards and displaced by a new layer of similar cells which form beneath them ; they are thus car- ried forward into the lacteal ducts, where the cell bursts and gives exit to its oil-globules, now become milk-globules; and the cell- membrane and nucleus are lost. These milk-globules suspended in a fluid, the milk-plasma, constitute the milk. Previously to concep- tion, the mammae only secrete a yellowish viscid mucus, and at the commencement of lactation the milk is imperfect and termed colo- strum, having entering into its composition a number of cells filled with yellow fat globules, named colostrum corpuscles. The mammary gland of the male is rudimentary ; it varies in size from a quarter of an inch to two inches in breadth, by one to three lines in thickness. It is firm in texture, presents no division into lobes, and its ducts are small without dilatations, and terminate in gland-vesicles larger than those of the female. At birth the mammary gland measures between two and four lines in breadth, and presents from twelve to fifteen lobular divi- sions, and then goes on gradually, but very slowly, increasing in bulk. True gland-vesicles do not make their appearance until the period of menstruation, and are not fully developed throughout the entire gland until the first pregnancy. After the period of child- bearing, the gland generally degenerates, the gland-vesicles dis- appear, and in old age the organ passes into a state of atrophy, the ducts, with their epithelium in a state of fatty degeneration, alone remaining, surrounded by a cushion of fat which takes the place of the glandular tissue. Vessels and Nerves.—The mammae are supplied with arteries from the thoracic branches of the axillary, the intercostals, and internal mammary ; having entered the substance of the gland they divide into capillaries, which constitute a close network around the gland-vesicles. The veins form an incomplete circle around the base of the nipple, circulus venosus Halleri, from which larger veins conduct the blood to the circumference of the gland, and by these communications form a plexus on its surface. They terminate in the axillary vein, internal mammary, intercostals, and jugular veins. The lymphatics are abundant in the integument covering the mammae. In the gland itself the lymphatic capillaries commence in the fibrous connective tissue between the gland vesicles, and the vessels formed therefrom accompany the veins and milk-ducts. The main lymphatic trunks run for the most part along the edge of the pectoralis major muscle to end in the axillary glands, but others pass through the intercostal spaces to reach the anterior mediastinal glands. The nerves of the mammary gland are derived from the ante- rior cutaneous branches of the second, third, and fourth inter- costal nerves, and from the lateral cutaneous branches of the same nerves. GLOSSARY OF ANATOMICAL TERMS. Abdomen (Lat. abdo, I conceal). The inferior cavity of the trunk, con- taining the stomach, intestines, liver, &c. Abductor (Lat. abduco, I draw from). A muscle which carries the limb away from the middle line of the body, or the digits from the middle line of the hand or foot. Accessorius (Lat. accedere, to be added to). Muscles or nerves which assist others in their action are thus named. Acervulus (dim. of Lat. acervus, a heap). Applied to the mass of gritty particles contained in the pineal body. Acetabulum (Lat. acetabulum, a vessel for holding vinegar). The cup- shaped cavity of the innominate bone which receives the head of the femur. Achromatin (Gk. a, not, and x/sw/ux, colour). The part of a nucleus which does not readily absorb staining fluids. Acini (Lat. acinus, a berry). The small vesicles which form conglomerate glands. Acromion (Gk. &Kpov, the extremity, and &yo$, the shoulder). The part of the scapula forming the tip of the shoulder. Adenoid (aSyv, a gland, and eldos, like). Tissue like that of the lymphatic glands. Adipose (Lat. adeps, fat). Fatty. Adductor (Lat. adduco, I draw to). A muscle which carries the limb towards the middle line of the body, or the digits towards the middle line of the hand or foot. Adventitia (Lat. adventitus, foreign). The outer coat of arteries and veins. Afferent (Lat. ad. to, and fero, I convey). Vessels or nerves which convey the contents or impulses from the periphery to the centre. Ala (Lat. ala, a wing). Term applied to the lateral lobe of the nose, the expanded part of the external ear, and to certain processes of the sphenoid bone. Alveoli (Lat. alveus, a cavity). The name given to the sockets of the teeth and the air-cells of the lung. Amoeboid (Gk. ayeipu, I change, and eldos, like). Movement like that of the Amceba, a single-celled organism living in the sea and fresh waters. Amphiarthrosis (Gk. apupi, both, and dpdpov, a joint. An articulation by means of some intervening substance, as that between the bodies of the vertebra:. Ampulla (Lat. ampulla, a wine-jug). The dilated end of a canal; chiefly used for the semicircular canals of the ear. 802 GLOSSARY OF ANATOMICAL TERMS. Amygdalae (Gk. dgvySdXr], an almond). The tonsils are so called from their resemblance to almonds. Anastomosis (Gk. ava, by, and arogd, a mouth). The intercommunica- tion of vessels. Anatomy (Gk. ava, through, and rep-vu, I cut). The Greek equivalent of “ Dissection.” Anchylosis (Gk. dyKvXos, crooked). An unnatural union between bones. Anconeus (Gk. dyswv, the elbow). A muscle situated near the elbow. Annulus (Lat. annulus, a ring). A circle or ring. Anti—as in anti-tragus, anti-helix, &c. (Gk. avri, against). Opposite, or opposed to. Antrum (Lat. antrum, a cave). The name given to a cavity in the superior maxillary bone, and a much smaller one in the mastoid. Anus (Lat. anus, an opening). The termination of the rectum which serves as an outlet for the fseces. Aorta (Gk. dopr-gp, a belt or strap to hang anything to). The main artery of the body is probably so called because it apparently suspends the heart. Aponeurosis (Gk. dub, from, and vevpov, a nerve). A tendinous expansion, so called because the early anatomists did not distinguish between tendons and nerves. Apophysis (Gk. dub, from, and cpuu, I grow). A projection from the surface of a bone. Appendices kpiploic.e (Lat.). Small fringes of fat attached to the large intestine. Arachnoid (Gk. apaxry, a spider’s web, and doos, like). The middle membrane of the brain. Arcuatum (Lat. arcuatus, bow-shaped). Name given, from their shape, to tendinous bands connecting the diaphragm with the last rib and first lumbar vertebra. Areola (Lat. diminutive of area, a void space). Term applied to inter- spaces in fibrous tissue. Artery (Gk. drip, air or spirit, and T-qptu, I keep). A vessel carrying blood from the heart. The ancients supposed the arteries contained the vital spirit or soul, and hence the name. Arthrodia (Gk. dpdpov, a joint). An articulation admitting of a gliding movement. Arthrology (Gk. dpdpov, a joint, and Xbyos, a discourse). A treatise on joints. Articulation (Lat. articulus, a joint). The means by which the bones of the skeleton are connected. Arytenoid (Gk. dpdraiva, a pitcher, and elSos, like). The two pyramidal cartilages of the larynx, so called from the supposed resemblance of the two together to the mouth of a pitcher. Asterion (Gk. aargp, a star). The point of junction of the occipital, parietal, and temporal bones. Astragalus (Gk. darpdyaXos, a die). One of the bones of the tarsus. Atlas (Gk. rXdco, I sustain). The vertebra which supports the head. Attollens (Lat. attollo, I raise up). Raising. The attollens auriculain muscle raises the pinna. Attrahens (Lat. ad, to, and traho, I draw). Drawing towards. The anterior extrinsic muscle of the ear is so called because it draws the ear forwards. GLOSSARY OF ANATOMICAL TERMS. 803 Auditory (Lat. audio, I hear). Belonging to the ear. Auricle (Lat. auricula, diminutive of auris, a little ear). The two superior cavities of the heart are so called because of their appendices which look like ears. Azygos (Gk. a, without, and fayos, a yoke). Without fellow. The term is applied to parts which are not in pairs. Bacillary (Lat. bacillum, a little rod). The layer of rods and cones of the retina is sometimes called the bacillary layer. Basilar (Lat. basis, a base). Belonging to the base of the brain or skull. Basilic (Gk. f3aoi\LKos, royal). A term generally of eminence, and hence applied to a large vein of the arm. Biceps (Lat. bis, twice, and caput, a head). Muscles having two heads receive this name. Bicipital. Adjective from the preceding. Bicuspid (Lat. bis, twice, and cuspis, a spear). Having two tubercles or points. Bipenniform (Lat. bis, twice, and penna, a feather). Applied to muscles having their fibres arranged on each side of a central tendon, like the barbs of a feather. Brachia (Lat. brachium, an arm). Two arms of nerve matter in the interior of the brain. Brachial (Lat. brachium, an arm). Belonging to the arm. Bregma (Gk. fipexw, I moisten). The anterior fontanelle. Bronchi (Gk. (3poyxos, the windpipe). The tubes which convey the air from the trachea to the lungs. Bronchocele (Gk. fipoyxos, the windpipe, and kt)\i7, a tumour). A per- manent enlargement of the thyroid gland. Buccinator (Lat. buccina, a trumpet). A muscle of the cheek, so called from its use in blowing. Bulbus (Lat. bulbus, an expanded underground stem). Applied to several rounded structures in the body, as the bulbus olfactorius and bulbus urethrae. Bursa (Lat. bursa, a sac). A closed sac containing fluid, and intended to modify pressure. C/ECUM (Lat. ccecus, blind). Any cul-de-sac is called caecum, but the term is especially applied to the expanded commencement of the large intestine. Calamus scriptorius (Lat. a writing pen). A groove upon the floor of the fourth ventricle. Calcaneum (Lat. calx, the heel). The heel bone. Calices (Gk. Ka\?), the head). Belonging to the head. Cerebellum (Lat. diminutive of cerebrum). The lesser brain. Cerebrum (Lat. the brain). The term applied to the greater brain or that part occupying the upper portion of the skull. Cervix (Lat. cervix, gen. cervicis, the neck). Ceruminous (Lat. ccra, wax). Glands secreting the ear wax. Chiasma (Gk. xtafw, I mark with the letter X; crossing or decussation). The commissure of the optic nerves. Choledochus (Gk. xoXi), bile, and dlx°P-ah I receive). Conveying bile. Chorda (Lat. a cord). A cord, tendon, or nerve filament. Ex. Chorda tympani nerve. Chorion (Gk. x6/>ior, skin or leather). One of the membranes of the embryo. Choroid (Gk. x°PL0Vi the chorion, and ddos, like). Term applied to the middle coat of the eye from its vascularity. Chromatin (Gk. xp&pa> colour). The part of the nucleus which has an affinity for staining fluids. Chromoplasm (Gk. xP^Pa> colour, and ir\a. juice). The fluid absorbed from the intestines by the lymphatics in digestion. Chylo-poietic (Gk. xi;X6s, juice, that is to say, chyle, and voilw, I make). Chyle-producing. Term applied to the viscera connected with the formation of chyle. Cilia (Lat. cilium, an eyelash). The eyelashes. Ciliary (Lat. cilium, a hair). Belonging to the eyelashes. Also, by extension, to the structures connected with the power of accommoda- tion in the eye. GLOSSARY OF ANATOMICAL TERMS. 805 Circumduction (Lat. circum, around, and duco, I lead). The slight degree of motion which takes place between the head of a bone and the socket, while the extremity of the limb is made to describe a large circle. Circumvallate (Lat. circumvcdlatus, trenched about). Claustrum (Lat. claudo, I shut). A layer of grey matter in the outer capsule of the corpus striatum. Clavicle (Lat. clavis, a key). The collar bone. Cleido-mastoid (Gk. /cAeis, a key, gaards, a nipple, and eldos, like). Con- nected with the clavicle and mastoid process. Clinoid (Gk. kX'lvt}, a bed, and eldos, like). The processes which border the sella turcica are so called because they bear some resemblance to the posts of a bedstead. Clitoris (Gk. K\eivu, I shut up). The homologue in the female of the penis of the male. Coaptation (Lat. con, together, and apto, I fit). The bringing successive articular areas into relation with another articular surface. Coccyx (Gk. kokkvI-, a cuckoo). The last bone of the vertebral column in man. It is supposed to resemble a cuckoo’s beak. Cochlea (Gk. k6%Aos, a shell-fish). A spiral cavity in the internal ear. Cceliac (Gk. KoiXia, the belly). Belonging to the belly. Colon (Gk. k&\ov, the colon). The large intestine. Commissure (Lat. committere, to unite). A joining together. Complexus (Lat. complecti, to comprise). A muscle at the back of the neck, so called because of the intricate mixture of its muscular and tendinous parts. Concha (Gk. kovxv, a shell). The central part of the external ear. Condyle (Gk. KdvdvXos, a knuckle). Term applied to certain articular osseous processes. Conjunctiva (Lat. con, together, and jungo, I join). The mucous mem- brane of the front of the eye, which connects the lids with the eyeball. Conoid (Gk. kuvos, a cone, and eldos, like). A cone-shaped portion of the coraco-clavicular ligament is so called. Constrictor (Lat. constringere, to bind tightly together). A muscle which constricts or closes any opening of the body. Coracoid (Gk. /copa£, a raven, and eldos, like). A process of the scapula supposed to resemble a ra ven’s beak. Corium (Gk. xoptov, leather). The deep layer of the skin. Cornea (Lat. corneus, horny). The anterior transparent part of the eye. Cornua (Lat. cornu, a horn). Processes which project like horns. Corona (Lat. corona, a crown). Forming a circlet like a crown. Corpus (Lat. corpus, a body, pi. corpora). A body. Hence we have the following :— Corpora albicantia (Lat. albico, I become white). Two whitish masses of nerve substance at the base of the brain. „ Arantii. Fibrous nodules in the semilunar valves of the heart, so named after the anatomist, Aranzi of Bologna. „ cavernosa (Lat. caverna, a cavern). Two elongated bodies, formed of erectile tissue, and forming the chief bulk of the penis and clitoris. „ geniculata (Lat. geniculum, a knot). Two small promi- nences of nerve matter situated at the back part of each thalamus opticus. 806 GLOSSARY OF ANATOMICAL TERMS. Corpora quadrigemina (Lat. quadrigeminus, four placed in two pairs). The masses of nerve matter with which the optic tracts are especially connected. They are also called optic lobes. „ striata (Lat. stria, a streak). The great motor ganglia of the cerebrum ; their streaked appearance is due to the presence of grey nuclei enclosed in white matter. Corpus callosum (Lat. callus, hard). The great transverse commis- sure of the brain. „ dentatum (Lat. dentatus, toothed). A small mass of grey matter having an irregular outline, and situated in the centre of the cerebellum and in the olivary body. ,, fimbriatum (Lat. fimbria, a fringe). The fringed edge of the fornix as seen in the lateral ventricle. „ Highmorianum. The central fibrous portion of the testicle, named after Highmore of Oxford. „ luteum (Lat. luteus, pale yellow). The cicatrix left in the ovary from the bursting of a Graafian vesicle. „ spongiosum (Lat. spongia, a sponge). The part of the penis which encloses the urethra. Corpuscle (Lat. corpusculum, diminutive of corpus, a body). A small body. Corrugator (Lat. corrugare, to wrinkle). A muscle which contracts the brow and produces wrinkles. Costal (Lat. costa, a rib). Pertaining to the ribs. Cotyloid (Gk. kotijXtj, a cup, and eldos, like). The cup-shaped cavity which receives the head of the femur. Cranium (Gk. xpaviov, the skull). The skull. Cremaster (Gk. Kpepaw, 1 suspend). The suspensory muscle of the testicle. Cribriform (Lat. cribrum, a sieve, and forma, likeness). Sieve-like. Cricoid (Gk. Kpisos, a ring, and eldos, like). One of the cartilages of the larnyx. Crista galli (Lat. a cock’s comb). A comb-like process of the ethmoid bone. Crus (Lat. crus, a leg). A process or peduncle of the brain. Crural— crureus. Belonging to the leg. Crusta (Lat. crusta, the rind or crust). The lower part of the crus cerebri. Cuboid (Gk. ki1/3os, a cube, and eldos, like). A cube-shaped bone. Cuneiform (Lat. cuneus, a wedge, and forma, likeness). Wedge-shaped. Cuneus (Lat. cuneus, a wedge). A wedge-shaped lobe of the brain. Cuticle (Lat. cuticula, diminutive of cutis, the skin). The superficial layer of the skin. Called also epidermis, and scarf-skin. Cystic (Gk. Kharis, a bladder or bag). Belonging to the urinary7 or gall bladder. Dartos (Gk. daprbs, flayed). The subcutaneous layer of the scrotum. Deglutition (Lat. deglutire, to swallow). The act of swallowing. Deltoid (Gk. A, and eldos, like). The muscle and ligament thus named resemble in shape the Greek letter D. Dentes sapienti.® (Lat. dens, a tooth, and sapientia, wisdom). Wisdom teeth. GLOSSARY OF ANATOMICAL TERMS. 807 Dentine (Lat. dens, a tooth). The tissue forming the body of the tooth. Derma (Gk. 8ipp.a, the skin). The deeper layer of the skin ; called also true skin. Diaphragm (Gk. did(ppayp.a, a partition wall). The muscle which sepa- rates the cavity of the abdomen from that of the thorax. Diaphysis (Gk. 8ia, through, and tpiiu, I grow). A term applied to the shaft of a long bone. Diarthrosis (Gk. Sia, through, and apdpov, a joint). A joint which is freely movable. Diaster (Gk. 5is, twice, and aarr/p, a,star). A stage of nuclear division. Dichotomogsly (Gk. Six a, double, and rip-vu, I cut). Dividing into pairs. Digastric (Gk. Sis, twice, and yaarrip, a belly). Two-bellied. Digital fossa (Lat. digitus, a finger, and fossa, a ditch). A depression such as might be produced by the tip of the finger. Diploe (Gk. 8in\ovs, double). The osseous tissue between the two tables of the skull. Disc (Lat. discus, a flat plate). Dissect (Lat. disseco, I cut to pieces). Duodenum (Lat. duodeni, twelve). The first portion of the small bowel was thus named by Herophilus, because it is twelve fingers’ breadth in length. Dura mater (Lat. dura, hard, and mater, mother). The outer membrane of the brain. Eleidin (Gk. 7]\os, a nail, and elSos, form). A peculiar organic principle found in the stratum granulosum of skin, and in nails. Embryo (Gk. iv, in, and fipuco, I bud forth). The foetus in utero. Emulgent (Lat. emulgeo, I milk or drain out). Term applied to the renal arteries. Enamel (Gk. iv, in, and Fr. email). The hard substance covering the crown of a tooth. Enarthrosis (Gk. iv, in, and dpdpov, a joint). A ball-and-socket joint, in which the rounded head of one bone is received into the cup-shaped socket of another. Encephalon (Gk. iv, in, and KerpaXg, the head). The brain. Endocardium (Gk. ivdov, within, and KapSia, the heart). The membrane lining the cavities of the heart. Endomysium (Gk. ivdov, within, and pus, muscle). The membrane lying between the fibres of muscle. Endothelium (Gk. ivbov, within, and Orfki7, papilla). Cells derived from the mesoblast, and lining serous surfaces. Ensiform (Lat. ensis, a sword, and forma, shape). The terminal piece of the sternum. Ephippium (Gk. ifinmov, a saddle). The ridge forming the back of the sella turcica is called dorsum ephippii. Epicranium (Gk. ini, upon, and Kpaviov, the skull). The periosteum of the skull. Epidermis (Gk. eiri, upon, and Sippa, skin). The superficial layer of the skin. Epididymis (Gk. eiri, upon, and bibvpos, the testicle). A small lobule con- nected with the testicle. Epigastrium (Gk. inL, upon, and yaarpp, stomach). The region of the abdomen in which part of the stomach lies. 808 Epiglottis (Gk. hr'i, upon, and y\corm, the glottis). The cartilage which covers the opening of the glottis in deglutition. Epineurium (Gk. eiri, upon, and vevpov, nerve). The nerve sheath. Epiphysis (Gk. eiri, upon, and bo), I grow). The pituitary body is called hypophysis cerebri, because it is connected with the under surface of the anterior part of the brain. Hypothenar (Gk. bird, under, and dbvap, the palm of the hand). Ileum (Gk. eiXew, I roll up). The lower three-fifths of the small intestine ; so called from its convolution. Iliac (Lat. ilia, the flanks). Belonging to the ilia or flanks. Impar (Lat. in, not, and par, equal). Odd or unequal. Ganglion impar. Infraorbital (Lat. infra, beneath, and orbs, a circle). Beneath the circle of the eye. Infundibulum (Lat. infundibulum, a funnel or tunnel). A funnel-shaped opening or canal. Inguinal (Lat. inguin, the groin). Belonging to the groin. Inion (Gk. cviov, the occiput). The external occipital protuberance. Inosculation (Lat. in, in, and osculum, a little mouth). The union of vessels, or anastomosis. Integument (Lat. in, in, and tego, I cover). The skin. Intercalary (Lat. inter, between, and calo, I insert). Placed or inserted between. GLOSSARY OF ANATOMICAL TERMS. 811 Tnternodia (Lat. internodium, the space between two knots). The inter- spaces between the joints of the fingers. Interosseous (Lat. inter, between, and os, a bone). Between the bones. Iris (Gk. Ipis, the rainbow). The iris is so called from its bright colours. Ischium (Gk. the hip). The hip bone. Jejunum (Lat. jejunus, empty). The upper two-fifths of the small in- testine, so named from this portion being generally found empty after death. Jugular (Lat. jugulum, the throat). Veins of the throat are so named. Karyokinesis (Gk. K&pvov, a kernel, and /colors, movement). Cell- division preceded by certain peculiar changes in the nucleus. Mitosis. KARYOSTENOSIS (Gk. icdpvov, a kernel, and crrerow, I contract). Cell- division without precedent nuclear elaboration. Labia (Lat. pi. of labium, a lip). The lips. Labia majora, the two large folds forming the external orifice of the pudendum, and the labia minora, the two smaller folds situated within them. Labyrinth (Gk. \aj3tipiv0os, a maze). The internal ear. Lacerum (Lat. lacerum, a torn opening). A term applied to irregular openings seen in the base of the skull. Lachrymal (Lat. laehryma, a tear). Pertaining to the tears. Lacunje (Lat. lacus, a lake). Small cavities. Lambda (Gk. letter A). The point of junction of the lambdoidal and sagittal sutures. Lambdoidal (Gk. letter A, lambda, and eldos, likeness). Formed like the Greek letter A. Larynx (Gk. Adpwif, the larynx). The upper part of the windpipe. Latissimus dorsi (Lat. latissimus, broadest, and dorsum, the back). The broadest muscle of the back. Lenticular (Lat. lens, lentis, a lentil). Lens-shaped. Levator (Lat. levare, to lift up). A muscle which raises any part. Ligament (Lat. ligare, to bind). A membrane which connects the arti- cular surface of bones and cartilages, and sometimes protects the joint by a capsular envelope. Linea aspera (Lat. linea, a line, and asper, rough). Lingual (Lat. lingua, a tongue). Relating to the tongue. Lingula (Lat. dim. of lingua, a tongue). A thin layer of bone, or of nerve matter of the brain. Locus perforates (Lat. locus, a place, and perforatus, bored). A per- forated space. Lumbricales (Lat. lumbricus, an earth-worm). The name of certain muscles of the hand and foot, so called from their resemblance to the earth-worm. Lunula (Lat. lunula, dim. of luna, the moon). The small white portions at the root of the nails. Lymph (Lat. lymplia, water). A colourless liquid of an alkaline character which fills the lymphatic vessels. Lymphatics (from preceding). The term applied to vessels containing lymph. 812 GLOSSARY OF ANATOMICAL TERMS. Lyra (Lat. lyra, a lyre). The name given to that part of the fornix which presents the appearance of some white lines somewhat re- sembling the strings of a lyre. Maceration (Lat. macerare, to make soft by steeping). The steeping of a body for some time in water, spirit, ether, wine, or vinegar, for purposes of softening. Malar (Lat. mala, the cheek). Belonging to the cheek. Malleolar (Lat. malleolus, dim. of malleus, a hammer). A term applied to two projections of bone which overhang the ankle-joint. Malleus (Lat. malleus, a hammer). The hammer bone, one of the small bones of the ear. Masseter (Gk. /j.aa a cord). The primitive vertebral column. Nucleus (Lat. nucleus, a kernel). A body usually found in the centre of a cell. Nymph.® (Gk. Nymphs). Two folds of mucous membrane situated within the labia majora of the pudendum, so called because they direct the course of the urine. Obelion (Gk. a mark). The slightly flattened area of the skull, near the parietal foramina. Obturator (Lat. obturo, I stop up). An aperture in the innominate bone which in the recent state is nearly closed by a membrane. Occiput (Lat. ob, caput, against the head). The back part of the head ; the part opposite to the front or sinciput. Odontoid (Gk. odobs, a tooth, and eTSos, like). Resembling a tooth. (Edema (Gk. from oidew, I swell). An infiltration of the subcu- taneous areolar tissue. (Esophagus (Gk. otw, oww, I carry, and cpdyeiv, to eat). The gullet. Olecranon (Gk. u\evr], the elbow, and Kpcivov, the head). The tip of the elbow. Olfactory (Lat. olfacere, to smell). Belonging to the sense of smelling ; the name of the first pair of cerebral nerves. Olivary (Lat. oliva, an olive). The olivary bodies are two olive-shaped eminences of the medulla oblongata. Omentum (Lat. omentum, the caul wherein the bowels are wrapped— Ainsworth). Omo-hyoid (Gk. tigos, the shoulder). Attached to the shoulder and the hyoid bone. 814 Ophthalmic (Gk. bpyv, the mind). Belonging to the diaphragm. The ancients supposed the diaphragm to be the seat of the mind, and hence they called it phrenes. Pia mater (Lat. pin, tender, and mater, mother). The innermost mem- brane of the brain. Pineal (Lat. pinus, a pine). A small body, situated in the interior of the brain, is called the pineal body. Pinna (Lat. pinna, a feather). The expanded part of the external ear. Pisibtirm (Lat. pisum, a pea). A bone of the wrist, shaped like a pea. Pituitary (Lat. pituita, the secretion of the nostrils). The body thus named was so called because it was erroneously supposed to be the source of the nasal mucus. Placenta (Lat. placenta, a cake). The after-birth. Plantaris (Lat. planta, the sole of the foot). A muscle which in the plantigrade animals makes tense the fascia of the sole of the foot. Platysma (Gk. 7rXarvaya, a flat piece). See Myoides. Pleura (Gk. vXevpd, side). A membrane which covers the inside of the ribs, and the outside of the lungs. Pneumogastric (Gk. nvebyeov, the lung, and yaaryp, the stomach). The great nerve distributed to the larynx, lungs, heart, and stomach. Pomum Adami (Lat. pomum, an apple). Adam’s apple. The anterior prominence of the thyroid cartilage. Popliteal (Lat. poples, the ham). The space behind the knee is so called, and certain nerves and vessels in it receive the same name. Portal (Lat. porta, a gate). The great vein which enters the liver through the transverse fissure (“gate of the liver”) is so named. Portio dura (Lat. portio, a part, and dura, hard). The facial nerve. Poupart’s ligament. The lower border of the aponeurosis of the external oblique muscle of the abdomen, attached to the anterior superior spine of the ilium and spine of the pubes. Prepuce (Lat. preputium.) The foreskin. Profundus (Lat. profundus, deep). Deep-seated. Pronator (Lat. pronus, face downwards). Muscles bringing the hand to the prone position are thus named. Prostate (Gk. irpd, before, and Harypu, I stand). A glandular body which stands in front of the bladder. Protoplasm (Gk. -n-pwros, first, and irXdjow, I form). The material of which all cells are originally formed. Pseudopodia (Gk. xj/evdys, false, and ttovs, a foot). Processes put out by free protoplasm. Pseudo-stomata (Gk. xpevbys, false, and arby.a, a mouth). Minute inter- cellular patches in serous membranes, which resemble openings but are not. Psoas (Gk. xjsba, the loin). A muscle of the loin. Pterion (Gk. a wing). The tip of the great wing of the sphenoid. Pterygoid (Gk. a wing, and eldos, like). Wing-like processes. Pubes (Lat. pubescens, covered with hair). Pudic (Lat. pudeo, I am ashamed). The arteries and nerves going to the perineum and external organs of generation are thus named. Pulmonary (Lat. pulmo, the lung). Belonging to the lungs, Punctum (Lat. punctum, a point). GLOSSARY OF ANATOMICAL TERMS. 817 Pylorus (Gk. TrvXwpos, a gate-keeper). The lower opening of the stomach. Pyriformis (Lat. pgr us, a pear, and forma, shape). A pear-shaped muscle. Quadratus (Lat. quadratics, square). The name of several muscles having a square form. Quadriceps (Lat.). Having four heads. Quadrigemina (Lat. quadrigemmus, four arranged in two pairs). Name given to the optic lobes of the brain, from their division into four. Racemose (Lat. racemus, a cluster of grapes). Clustered. Raohidian (Gk. paxis, the spine). Belonging to the spinal column. Radius (Lat. radius, a ray, or spoke of a wheel). One of the bones of the forearm. Ramus (Lat. ramus, a branch). Ranine (Lat. rana, a frog). This word seems to be derived from ranula, an affection which is supposed to resemble a frog. Raphe (Gk. patp-f a seam). The line of junction of two lateral parts. Rectus, Rectum (Lat. rectus, straight). A straight muscle or tube. Renal (Lat. ren, the kidney). Belonging to the kidney. Restiform (Lat. rest is, a cord). A cord-like band. Retina (Lat. rete, a net). The nervous net-work of the eye. From the same root we have rete mucosum, rete testis, and others. Retinacula (Lat. retinere, to hold back). Fibrous bands on the back of the neck of the femur. Risorius (Lat. video, I laugh). The risorius Santorini is the muscle which produces the sardonic smile. Rotula (Lat. dim. of rota, a wheel). The patella. Rug.'E (Lat. ruga, a wrinkle). Term applied to certain folds of mucous membrane. Sacculus (Lat. dim. of saccus, a bag). A membranous bag in the in- ternal ear. Sacrum (Lat. saeris, sacred). The sacrum was offered as a sacrifice by the ancients. Sagittal (Lat. sagitta, an arrow). Term applied to the straight suture between the parietal bones. Salpingo-pharyngeus (Gk. a trumpet). Name given to a muscle which passes from the Eustachian tube to the pharynx. Saphenous (Gk. aafgvgs, manifest). Name given to the superficial veins of the leg, because they are usually prominent. Sarcolemma (Gk. aapf flesh, and Xep.pa, a covering). The covering of the muscular fibres. Sartorius (Lat. sartor, a tailor). The muscle thus named is used in crossing the legs. Scala (Lat. scala, a stair). Three spiral passages in the cochlea are so called. Scalenus (Gk. aKaXgvos, a geometrical figure having three unequal sides). The name of several muscles of the neck which are triangular in shape. Scaphoid (Gk. v, together, and (pvu, I grow). “An articulation in which there is no manifest motion ” (Hoblyn). Synarthrosis (Gk. . , . i 377 palmar, superficial . . 416 plantar 44s Arciform fibres . . . 492 nucleus . . . .494 Areola of nipple .... 798 Areolae, primary .... 25 secondary .... 26 Areolar tissue x Arteries : general anatomy ... 43 structure 44 acromial-thoracic .... 408 alar-thoracic 408 anastomotic of arm . . .410 , leg . . . 440 angular ,87 articular of knee . . . ! 441 auditory 4QI auricular anterior . . . 389 posterior . . . 388 axillary 405 basilar . . . . . 400 brachial bronchial . 4i‘7, 692 buccal bulbo-urethral .... 432 calcanean 447 capsular 426 cardiac ..... 380, 672 carotid, common . . . .381 external .... 383 internal . . . .393 carpal, radial ulnar. . . . . $ cavemosal 433 central of retina .... 3g6 cerebellar .... 400, 401 cerebral 397, 525 cervicalis ascendens . . . ’ 404 profunda . . .405 superficialis . . .404 choroid 397 ciliary -396 circumflex femoris . . . 438 humeri . . .408 coccygeal . . . . 43f’ 43o INDEX 823 Arteries—continued. page cceliac 419 colic ...... 424 comes nervi ischiatici . . . 430 mediani . . .415 phrenici . . . 402 communicans cerebri . . . 397 coronary of heart .... 380 lips .... 387 stomach . . . 419 corporis cavernosi . . . 432 cremasteric 435 crico-thyroid 384 cystic ...... 422 deferential 429 dental 391 diaphragmatic .... 419 digital of hand . . . .416 foot .... 448 dorsales pollicis .... 413 dorsalis hallucis .... 445 indicis .... 413 linguae . . . .385 pedis .... 444 penis .... 432 scapulae .... 408 emulgent 426 epigastric .... 403, 434 superficial . . .437 ethmoidal 396 facial 386 facial, transverse .... 389 femoral 435 frontal 396 gastric ...... 419 gastro-duodenal .... 420 gastro-epiploica dextra . . 421 sinistra . . 422 gluteal 433 haunorrhoidal . .425, 429, 431 helicine 773 hepatic 419, 748 hyoid 384, 385 hypogastric 427 ileo-colic 423 iliac, common .... 427 external .... 434 internal .... 427 ilio-lumbar 432 infra-orbital 392 innominate 381 intercostal 417 anterior . . . 402 superior . . . 405 interosseous 415 intestini tenuis .... 423 ischiatic 430 labial 387 lachrymal 395 laryngeal 384 lateral nasal 387 sacral 433 lingual 385 lumbar 426 magna pollicis . . . -413 malleolar 443 mammary 408 internal . . . 402 Arteries—continued. page mastoid 388 maxillary, internal . . 390 mediastinal 402 meningeal, anterior . . . 396 inferior . . . 389 lesser .... 392 middle . . . 392 posterior . . . 400 mesenteric, inferior . . . 424 superior . . . 422 metacarpal .... 412, 416 metatarsal 444 musculo-phrenic . . . . 403 mylo-hyoid . .. . . 391 nasal . . . . . 387, 396 nutrient of humerus . . . 410 tibia .... 446 obturator 429 occipital 388 oesophageal ..... 417 ophthalmic 394 orbital 390 ovarian 424, 793 palatine, anterior . . . 393 ascending . . . 386 descending . . . 393 palpebral 396 pancreatica magna . . . 422 pancreaticfe parvse . . . 422 pancreatico-duodenal . . 421, 422 parotidean 389 perforating, femoral . . . 439 palmar . . . 414 plantar . . . 448 pericardiac 402 perineal, superficial . . . 431 peroneal 446 pharyngeal, ascending. . .388 phrenic 419 plantar 447 popliteal 441 princeps cervicis .... 388 pollicis . . . .413 profunda cervicis .... 405 femoris .... 438 inferior . . . .410 superior.... 409 prostatic 770 pterygoid 393 pteiygo-palatine . . . .393 pubic 429, 43 s pudic, external .... 438 internal . . . 430, 432 pulmonary . • . . . 449, 665 pyloric 420 radial 411 radialis indicis . ... . 413 ranine . . . .' . . 386 receptacular 394 recurrent, interosseous . . 416 radial .... 412 tibial .... 443 ulnar . . . .415 renal ..... 426, 762 sacral, lateral .... 433 middle .... 426 scapular, posterior . . . 404 824 INDEX Arteries—continued. page sigmoid 424 spermatic . . . . 424, 778 spheno-palatine .... 393 spinal 400 splenic 422, 755 sterno-mastoid .... 384 1 stylo-mastoid .... 388 subclavian 397 sublingual 385 submaxillary 387 submental 387 subscapular 408 superflcialis vola: .... 412 supra-orbital .... 395 supra-renal .... 426, 757 supra-scapular .... 404 sural 442 Sylvian 397, 527 tarsal ...... 444 temporal, deep .... 392 superficial . . .389 thoracic .... 407, 408 thymic 402 thyroidea ima . . . .381 thyroid, inferior .... 403 lowest . . . .381 superior . . . . 383 tibial, anterior .... 442 posterior .... 445 tonsillar 387 transversalis colli . . . 404 humeri . . . 404 perinei . . . 432 tympanic . . . . 391, 394 ulnar 414 umbilical .... 427, 674 uterine 429, 790 vaginal 429 vasa brevia .... 422 intestini tenuis . . . 423 of vas-deferens . . . 429 vertebral 399 vesical 429, 768 Vidian 393 Arthrodia 179 Arthrology 175 Articulations . . . . 175, 178 Arytenoid cartilages . . . 676 glands .... 683 Asterion 528 Aster stage 4 Atrium 660 Auerbach, plexus of 735 Auricles of the heart . . 660, 665 Auriculo-ventricular openings 663, 667 Axis, coeliac 419 thoracic 408 thyroid 403 Axis cylinder 34 Bartholin’s duct .... 708 glands .... 797 Base of the brain .... 497 Basement membrane . . .16 Bauhin, valve of . . . .739 Bertin, bones of . . . .102 Bertini, columns of . . . . 759 PAGE Bicuspid teeth 711 Biliary ducts . . . . 748 Bladder . . . . . . 765 Blood 4 clot ...... 4 corpuscles .... 5 platelets 6 Blood-vessels, structure of -42 Bochdalek, ganglion of . . . 545 Body, pineal 515 Bodies, supra-renal . . . .756 Bones: chemical composition . .20 development .... 24 minute structure . . .21 number of 73 structure 20 astragalus 167 atlas 76 axis 77 calcis 168 carpus 146 clavicle 136 coccyx .86 coxaj 153 cuboid 171 cuneiform, of carpus . . .148 external of tarsus . 171 internal . . . 169 middle . . .170 ethmoid 105 femur 160 fibula 166 frontal 92 humerus 140 hyoid 131 ilium ...... 154 incus 639 innominate 153 ischium -155 jugal 112 lachrymal m lingual 131 magnum 150 malar . . . . . . n2 malleus 638 maxillary, lower . . . .117 upper . . . .107 metacarpus 151 metatarsus 172 nasal 107 occipital 87 orbicular 640 palate 113 parietal 90 patella 163 pelvis 153, 158 phalanges of hand . . .153 foot .... 173 pisiform 148 pubes 156 pyramidal 148 radius 145 ribs 133 sacrum 84 scaphoid of carpus . . .147 tarsus . . .169 INDEX. 825 Bones—continued. page scapula 137 semi-lunar 147 sesamoid of hand . . . .174 foot .... 174 sphenoid 100 spongy 102 stapes 640 sternum 131 tarsus 167 temporal 94 tibia 164 trapezium 149 trapezoid 150 triquetra 120 turbinated, inferior . . .1x5 superior . . . 106 tympanic 99 ulna 143 unciform 151 vertebra prominens ... 78 vertebrae, cervical . . -75 dorsal .... 78 lumbar .... 80 vomer 116 Wormiana 120 Botal, foramen of . . . . 672 Bowman’s discs .... 29 Brachia cerebri . . . .515 Brain 497 Bregma 528 Bronchi 684, 688 Bronchial tubes .... 688 Bronchocele 686 Bruch, membrane of 624 Brunner’s glands .... 732 Bulb of corpus spongiosum . . 773 olfactory 537 Bulbous part of the urethra . . 777 Bulbs of fornix .... 499 Bursae mucosa) . . . . 58, 177 Cfecum 73S Calamus scriptorius. . -519 Calcarine fissure .... 505 Calices 759 Canal of Alcock . . . .313 Hannover . . . -633 Huguier ... 98 Hunter .... 436 Nuck 795 Petit 633 Schlemm .... 624 Stilling . . . .631 Canaliculi of bone .... 22 lachrymal . . . 620 Canals of Havers . . . .21 Cancelli of bone .... 20 Canine teeth 710 Canthi 616 Capillaries 47 Capsule of Glisson .... 746 Tenon . . 236, 615, 621 Caput coli 735 gallinaginis .... 776 Carpus 146 Cartilage, articular . . . .18 elastic . . . .18 Cartilage—continued. page fibro .... 19 hyaline . . . .17 interarticular of clavicle 198 jaw . 189 wrist . 205 of Meckel . . .119 permanent ... 18 reticular . . . .18 semi-lunar . . . 216 temporary . . .18 xiphoid . . . .132 Cartilages, arytenoid . . . 676 bronchial . . . 689 costal . . . .135 of larynx . . . 675 Santorini . . . 676 trachea . . . 684 Caruncula lachrymalis . . .619 mamillaria . . . 499 sublingualis . . . 704 Carunculse myrtiformes . . . 797 Cauda equina 486 Cava, vena 464 Cells 1 epithelial 7 ethmoidal .... 106 hepatic 745 Cell division 3 direct .... 3 indirect. ... 3 Cement 715 Centrum ovale 506 Cerebellum 516 structure of . . -517 Cerebro-spinal axis .... 485 fluid . . 533, 535 Cerebrum 497 transverse section of . 521 Ceruminous glands . . .72, 636 Cervical ganglia .... 602 Chambers of the eye . . . 631 Cheeks : 703 Chiasma of optic nerves . . . 538 Chondrin 19 Chordae longitudinales . . . 507 tendinse . . . 663, 667 Chordae vocales .... 678 Willisii .... 4S4 Chorio-capillaris .... 624 Choroid coat 624 plexus 508 Chromatin 3 Ohromoplasm . . . . . 3 Chyle 7 Cilia 618 Ciliated epithelium 10 Ciliary ligament 627 processes .... 626 Circle of Willis .... 402 Circulation, adult .... 660 fuetal .... 672 Circulus tonsillaris .... 555 venosus Halleri. . . 800 Willisii .... 402 Claustrum 523 Clava . . ... 493 Clitoris . ... 796 826 INDEX. PAGE Clivus Blumenbachii . . .101 Clot, blood 4 Cochlea g45 Coccygeal gland . . . .611 Cceliac axis 4,g Cohnheim, polygonal areas of . 30 Colon 735 Colostrum ..... 800 Column of Burdach. . . [487 doll . . . .4g7 Columna of nose . . . .611 Column® carnese . . . 664, 667 Columnar epithelium ... 8 Commissures SI4 Commissure, great . . . ! 506 Concha g34 Condylarthrosis . . . ! 180 Cones of retina .... 629 Congenital hernia . . . .297 Coni vasculosi 78i Conjunctiva 619 Connective tissue . . . . „ Conus arteriosus .... 668 medullaris .... 485 Convolutions SOI structure of . . 505 Coracoid process . . . .139 Corium so, 63 Cornea 622 Cornicula laryngis . . . . (,76 Cornu Ammonis .... 510 Cornua of the ventricles . . .510 Corona glandis 77I Coronary valve 662 Corpora albicantia . . . '■ 4gg Arantii . . . 665) 668 cavernosa .... Ooo geniculata . . . .513 Malpighian a . . 754, 76o mammilaria . . .499 olivaria . . . .491 quadrigemina . . .514 restiformia .... 493 striata 522 Corpus callosum . . . ’ so6 cavernosum .... 772 dentatum . . . 495, 518 fimbriatum . . . 5og, 511 geniculatum. . . -513 Highmorianum . . .780 luteum 794 spongiosum . . .773 striatum . , , 508, 522 Corpuscles of blood . . . . ’ 5 Pacinian.... 39 Corpuscula tactus .... 67 Corti, organ of 649 Costal cartilages . . . "135 Costo-coracoid membrane . . 318 Cotunnius, liquor of 646 Cotyloid cavity . . . .156 Cowper’s glands . . . .777 Cranial nerves <-,g Cranium ’ I2I Cribriform fascia . . ’ 343 Cricoid cartilage . . . .676 Crico-thyroid membrane. . .677 PAGE Crura cerebelli cerebri . . . 4gg of diaphragm . . . 2gg penis • • . . . 771 Crural arch . . 2g5 canal 345 I'ing .... o4e Crystalline lens . 632 Cuneiform cartilages . . . 677 Cuneate tubercle ... 403 Cuneus lobe roc Cupola .... g, r Cuticle i Cutis gZ Cylinder epithelium. ! ! ! 8 Cystic duct 75I Dartos 77g Decussation of pyramids. . ! 491 Deglutition, mechanism of . . 265 Deiters, cells of . . . .488 Demours, membrane of . . ’ 623 Dentine 7I2 Derbyshire neck . . [ 686 Derma ' g, Descemet, membrane of . . . g23 Descent of testicle .... 7g4 Detrusor urinse .... 766 Development of bone . . . 24 intracartilaginous 25 _. , intramembranous 24 Diaphragm 2qo Diaphysis Diartlirosis . . . ’ ! 179 Diaster stage . .... 4 Digital fossa . . . . t6o Oiploe ; 20 Dobie’s line 2g Dorsi-spinal veins . . . ! 460 Douglas, fold of . . . .203 Duct of Gaertner .... 7g2 nasal ....’. g21 Wharton’s . . . ! 707 Wirsung, of . . .752 Ductus arteriosus .... 672 Bartliolini .... 708 communis choledochus ! 740 cysticus . . . .751 ejaculatorius . . . 783 galactophorus . . .799 hepaticus . . . .749 lymphaticus dexter . . 4s4 pancreaticus . . . 752 prostaticus .... 769 Riviniani .... 7o8 Stenson’s . . . .707 thoracicus . . . . 482 venosus .... 673 Duodenum 72g Dura mater .... 530, 534 Bar ....... 633 Ejaculatory duct . . . .783 Elastic tissue Elbow, bend of . . . .410 Eminentia collaterals . . .511 INDEX. PAGE Enamel 714 Enarthrosis 180 Encephalon 491 End bulbs 41 Endocardium 671 Endolymph 646 Endomysium 28 Endoneurium 38 Endothelium 11 Engelmann, discs of ... 29 Ensiform cartilage .... 132 Ependyma ventriculorum . . 524 Epidermis 64 Epididymis 779 Epigastric region .... 697 Epiglottic gland .... 683 Epiglottis 677 Epineurium 38 Epiphysis 27 cerebri .... 515 Epithelium 7 ciliated. ... 10 columnar ... 8 cylinder* ... 8 glandular ... 9 goblet .... 9 non-stratifled . . 7 scaly .... 8 spheroidal ... 9 squamous ... 8 stratified ... 7 tesselated . 8 transitional ... 9 Erectile tissue 773 Eruption of teeth .... 719 Eustachian tube .... 642 valve .... 661 Eye ....... 621 Eyebrows 616 Eyelashes 618 Eyelids 616 Eye-teeth 710 Falciform border .... 344 Fallopian tubes . . . - 791 Fallopius, aqueduct of . . . 642 hiatus of . . . .97 Falx cerebelli 531 cerebri 530 FASCIA : arrangement of. . . . 228 abdominal 294 anal 315 axillary 315 brachial 315 cervical 248 Colles, of . . . . . 303 cribriform 343 dentata 511 dorsal of hand . . . .316 iliac 344 infundibuliform . . ... 295 intercolumnar .... 288 1 lata ...... 343 lumbar 291 obturator 313 F ASOIA—continued. page palmar 317 parotideo-masseteric . . . 248 pelvic 311 perineal 303 plantar 348 popliteal 347 recto-vesical 314 spermatic 288 supra-hyoidean . . . .254 temporal 244 transversalis 294 Fasciculi teretes .... 520 of muscle . ... 28 Fauces 705 Femoral arch 346 canal ..... 345 hernia . . . . 346 ring 345 Fenestra ovalis 638 rotunda . . . .638 Fenestrated membrane . . 15, 45 Fibres, arciform .... 492 of heart .... 670 Fibrils of muscle .... 29 Fibrin 6 Fibrin-factors 6 Fibrin-ferment 6 Fibrinogen 6 Fibrinoplastin 6 Fibro-cartilage 19 interarticular of the clavicle 198 jaw 189 knee 216 wrist 205 Fibrous tissue 13 Filum terminale .... 488 Fimbria.', Fallopian . . , .791 Fissure calcarine .... 505 collateral .... 505 dentate .... 305 Glaser, of . . .98 longitudinal . . . 497 Rolando, of. . . . 501 Sylvius, of . . . 498, 501 transverse . . . 507, 511 Fissures of the spinal cord . . 486 Fissures of the liver . . . 741 Santorini . ,. . 634 Flocculus 516 Flood, ligament of . . . .201 Foetal circulation .... 672 Folia cacuminis . . . .517 Foltz, valve of 620 Follicles, gastric . . . .726 of Iiieberkunn . . . 732 Fontana, spaces of . . . . 624 Foramen, Botal, of . . . . 672 csecum . . 93, 491, 654 commune anterius . . 309 Magendie, of . . . 320 Munro, of. . . 509, 514 obturator . . . .157 ovale . . 157, 662, 672 Soemmering, of . . 628 thyroid . . . .157 Vesalius, of 103 828 INDEX. PAGE Foramen, Winslow, of . . . 700 Foramina, Scarpa, of . . .hi Stenson, of . . . m Thebesii .... 661 Fornix 512 Fossa, hyoid . . . . . 682 innominata .... 634 ischio-rectal .... 303 navicularis urethra; . . 777 pudendi . . 796 ovalis 662 of Rosenmtiller . . .721 scaphoid 634 Fovea hemielliptica.... 644 hemispherica.... 644 Fovese of fourth ventricle . . 520 Fourchette 796 Fran a epiglottidis . . . -677 Franulum clitoridis . . . 796 Fncnum labise 703 linguee . . . 652, 704 praputii .... 771 Frommann’s lines .... 34 Funiculus cuneatus .... 493 gracilis .... 493 of Rolando . . 493 solitarius . . . 496 Gaertner, duct of ... 792 Galactophorus ducts . . . 799 Gall-bladder 750 Ganglia, cervical .... 602 lumbar .... 609 sacral 610 semilunar .... 608 structure of ... 37 thoracic .... 607 Ganglion, Andersch, of . . . 553 Arnold’s .... 600 azygos . . . .611 Bochdalek, of . . . 545 cardiac .... 606 carotid .... 603 ciliary . . . -597 Cloquet’s .... 599 diaphragmatic. . . 608 Gasserian.... 539 geniculate . . . 548 hypogastric . . . 790 impar . . . .611 jugular . . . .553 lenticular . . . 597 Meckel’s .... 599 naso-palatine . . . 600 ophthalmic . . . 597 otic ..... 600 petrous .... 553 Ribes, of ... 602 semilunar . . . 608 spheno-palatine . . 599 submaxillary . . . 601 thyroid .... 603 vertebral .... 603 Wrisberg, of . . . 606 Ganglion cells 37 Gastro-colic omentum . . . 701 Gastro-hepatic omentum. . . 700 PAGE Gastro-phrenic ligament. . . 702 Gastro-splenic omentum. . . 702 Genu corporis callosi . . -507 Germinal eminence .... 794 spot 794 vesicle .... 794 Giant-cells .... 24, 27 Gimbernat’s ligament . . . 288 Ginglymus 179 Giraldes, organ of . . . . 783 Gland, epiglottic .... 683 prostate .... 769 thymus .... 695 thyroid .... 685 Glands, absorbent .... 53 arytenoid .... 683 axillary .... 476 Bartholin’s . . . -797 bronchial . . . 480, 692 Brunner’s .... 732 ceruminous. . -72, 636 concatenate . . . 475 Cowper’s .... 000 duodenal .... 732 femoral .... 477 follicular .... 61 gastric .... 726 inguinal .... 477 lachrymal .... 620 lenticular .... 733 Lieberktihn’s . . -732 lingual . . . 655, 706 Littre, of ... 775 lymphatic .... 53 mammary .... 798 Meibomian .... 617 mesenteric .... 481 odoriferee . . . . 771 Pacchionian . . . 454 parotid .... 707 Beyer’s . . . -734 racemose .... 61 saccular .... 61 salivary .... 707 sebaceous .... 70 secreting .... 60 solitary .... 733 sublingual .... 708 submaxillary . . . 707 sudoriferous . . -71 tracheal 685 Glands, tubular .... 61 Tyson, of . . -771 uterine .... 790 Glandulse odoriferee. . . .771 Pacchioni. . . • . 454 Tysoni . . . .771 Gians clitoridis .... 796 penis 770 Glenoid cavity 138 Glisson’s capsule .... 746 Globus major epididymis . . 782 . minor epididymis . . 782 Glomerulus 760 Glossary of terms .... 801 Glottis 682 Goblet cells .... 9 INDEX. PAGE Incisura cerebelli .... 516 Infundibula 764 Infundibulum 499 Inguinal canal 295 region .... 697 Inion 528 Inosculation 43 Inscriptiones tendimc . . . 292 Interarticular cartilages of the clavicle 198 jaw 189 knee 216 wrist 205 Intercolumnar fibres . . ■ 288 Intermaxillary bone . . .no Intervertebral substance . . 183 Intestinal canal .... 727 Intra-cartilaginous ossification . 25 Intra-membranous ossification . 24 Intumescentia gangliformis . . 548 Intussusception, movement of . 3 Involuntary muscle ... 31 Iris 625 Island of Iteil 503 Isthmus of the fauces . . ■ 7°5 Iter ad quartum ventriculum . 514 Jacobson, cartilage of 614 nerve of . . . 553> 643 organ of . . . . 614 Jejunum ...... 729 Joint, ankle 220 elbow 202 hip 210 lower jaw . . . .188 knee 213 shoulder . . . .201 wrist 205 Karyokinesis 3 Karyostenosis 3 Kerkring, valves of . . . ■ 730 Kidneys 758 Krause, end bulbs of . 41 membrane of . . 29 Labia majora 796 minora 796 Labyrinth 643, 646 Lachrymal canaliculi . . .620 gland . • • .620 papilla) . . • 617, 620 puncta . . .617, 620 sac 621 Lacteals 482 Lacunae of bone .... 22 Lacus lachrymalis . . ■ .616 Lambda 528 Lamella) of bone .... 22 Laminated tubercle . . -517 Lamina cinerea .... 498 cribrosa .... 622 fusca 622 spiralis .... 645 Laryngotomy . . • .678 Larynx ...... 673 Lateral ventricles . . . .508 Lens 632 829 PAGE | Goitre 686 : Gomphosis 179 ■ Graafian vesicles . . . -793 Ground substance . . . 12 J Gubernaculum testis . • 783 Gums 7°3 Gyri, annectant .... 503 frontal 5°2 operti 5°3 temporo-sphenoidal . . 503 Gyrus fornicatus .... 504 Hair 68 Hannover, canal of . . . -633 Hasner, valve of ... 621 Hamulus of cochlea . . ■ 646 Harmonia 178 Haversian canals . . . .21 lamella) . . . .21 systems . . . .21 Heart 659 foetal 672 in relation to chest wall . 668 muscle of .... 31 size of 672 weight of . ■ • .672 Helicine arteries 773 Helico-trema 646 Helix 633 Hemispheres, cerebral . . . 497 Hensen, disc of ... • .29 Hepatic cells 745 duct- 748 Hernia, congenital . • • -297 diaphragmatic . . . 299 direct 297 encysted .... 297 femoral .... 346 infantile . . . • 297 inguinal .... 296 scrotal .... 298 Hesselbach, triangle of . . . 43s Hiatus Fallopii .... 97 Hilton's law 177 Hilum lienis 753 renale 758 Hippocampus major . . .510 minor . . • 510 Histology 1 Horner's muscle .... 232 Huguier, canal of 981 637 Humours of the eye . . .631 Hunter’s canal 436 Huschke, valve of . . . • 620 Hyaloid membrane .... 631 Hyaloplasm 2 Hydatids'of Morgagni . . .780 Hymen . . , • • -797 Hypochondriac regions . . 697 Hypogastric region . . . -697 Hypophysis cerebri .... 499 Ileo-csecal valve . . • -739 Ileo-colic valve .... 739 Ileum ... • 729 Iliac regions 697 Incus 639 830 INDEX. PAGE Lenticular ganglion . . . 597 Levers 323, 367 Lieberkuhn’s follicles . . . 732 Ligament 176 Ligaments 17s accessory 192 acromio-clavicular . . .199 alar . . . . . 217 ankle, of the 220 annular, ankle, of the . . . 347 radius .... 204 wrist, anterior . 207, 316 posterior . 207, 316 arcuatum externum . . .301 internUm . . . 300 astragalo-calcaneal . . . 222 scaphoid . . . 222 atlanto-axial . . . .187 bladder, of the .... 766 breve plantaj .... 223 calcaneo-cuboid .... 223 scaphoid . . . 222 capsular, hip, of the . . .211 jaw . . . .189 rib 191 shoulder . . .201 thumb .... 209 carpal . . ... . . 207 carpo-metacarpal .... 208 chondro-sternal .... 192 xyphoid . . . .192 common, anterior . . .182 posterior . . .182 conoid 200 coracoid 200 coraco-acromial .... 200 clavicular .... 199 humeral .... 201 coronary 204 of the knee . . . 215 corruscantia 192 costo-clavicular . . . .198 coracoid . . . .318 transverse . . . .191 vertebral . . . . 190 cotyloid 212 cranio-pharyngeal.... 259 crico-thyroid .... 677 crucial 215 cruciform .... 187, 347 deltoid 220 dentatum ...... 535 elbow, of the .... 202 Gimbernat’s 288 glenoid 201 gleno-humeral . . . .201 glosso-epiglottic .... 679 hip-joint, of the .... 210 liyo-epiglottic . . . .679 ilio-femoral 211 ilio-lumbar ig3 incus, of 640 interarticular of ribs . . .191 inter-clavicular . . . .198 intermuscular .... 315 interosseous astragalo-calcaneal . . . 223 Ligaments—continued. page carpal 207 peroneo-tibial .... 219 radio-ulnar .... 204 interspinous 184 inter-trans verse . . . .184 intervertebral . . . .183 jaw, of the 188 knee, of the ...... 213 larynx, of the . . . -677 lateral, of the ankle . . . 220 elbow . . . 203 jaw . . .188 knee . . . 214 phalanges, foot . 226 hand . 210 wrist . . . 206 liver, of the .... 698, 740 longum plan he .... 223 malleus, of 640 metacarpal 209 metatarsal 225 mucosum 216 nucha; 271 oblique 204 obturator 197 occipito-atlantal . . . .185 axial . . . .186 odontoid . . . .> . 186 orbicular 204 palpebral 617 patella; 213 phalanges of the foot . . . 226 hand. . . 210 plantar, long 223 short .... 223 posticum Winslowii . . . 213 Poupart’s 288 pterygo-maxillary. . . .245 pubic 196 radio-ulnar 205 rhomboid 198 round of uterus .... 795 liver . . . .741 saero-coccygean . . . .196 sacro-iliac 194 sacro-ischiatic .... 195 sacro-lumbar . . . .193 sacro-vertebral . . . .193 spheno-maxillary . . . .188 stellate 190 sternal 193 sterno-clavicular . . . .197 sterno-xyphoid . . . .193 stylo-maxillary . . . 190, 249 sub-flava 183 sub-pubic 197 supra-scapular .... 200 supra-spinous . . . .184 suspensorium dentis . . .186 hepatis . . .741 penis . .771 tarsal 222 tarso-metatarsal .... 225 teres 2n tliyro-arytenoid . . . .678 thyro-epiglottic .... 679 thyro-hyoid ..... 677 INDEX. Lymphatics—continued. page intestines 481 kidneys 482, 764 lacteals 51, 482 liver 481 . lower extremity .... 477 lungs 692 mammary .... 479, 800 mediastinal 479 mesenteric 481 pancreas 481 pelvic viscera .... 482 popliteal 478 spleen 481, 755 stomach 481 testicle 482 thymic 696 trunk 479 upper extremity .... 476 uterus, of the . . . 482, 790 viscera 480 Lymphoid tissue .... 16 Lyra 5*3 Macula acustica .... 647 crihrosa .... 644 lutea 628 Magendie, foramen of 520 Malleus 638 Malpighian corpuscles . . .762 glomeruli . . . 760 pyramids . . . 759 Mammae 798 Mammary gland .... 798 Marrow of bones .... 23 Mastoid cells 641 Matrix 68 Maxillo-pharyngeal space . . 261 Meatus auditorius . . 96, 641, 651 urinarius, female . . 797 male . . -771 Meatuses of the nose . . .13° Meckel’s ganglion . . . -599 Median disc of Hensen ... 29 Mediastinum 693 testis .... 780 Medulla, course of fibres in . . 526 of bones .... 23 oblongata . . . .491 Medullary sheath .... 33 Medullary velum, anterior . . 520 posterior . . 517 Meibomian glands .... 617 Meissner, plexus of . . . . 735 Membrana basilaris .... 649 eboris . . . . 717 flaccida .... 638 fusca .... 622 interosseous . . 204, 219 nictitans . . . 620 pupilaris . . . 626 sacciformis . . . 208 tectoria 649 tympani . . . 638 Membrane, Bruch, of 624 choroid .... 624 Corti, of 649 costo-coracoid . . 3x8 Ligaments—continued page tibio-fibular 219 transverse of the acetabulum . . .212 ankle .... 219 atlas . . • .187 knee .... 215 metacarpus . . .209 metatarsus . . .225 scapula .... 200 semilunar cartilages . 216 trapezoid 200 triangular 3°4 tympanum, of the . . • 640 uterus, of the .... 795 vertebral i82 wrist, of the 205 Zinn, of . . . • • - 234 Ligamentum denticulatum . -535 nuchse . . .271 pectinatum . . 623 Ligula 520 Lingula 5r7 Limbus luteus 628 Linea alba z87 Linea; semilunares .... 287 transversse . . . 287, 507 Lips . . _ 703 Liquor Cotunnn .... 040 sanguinis .... 4 Littre, glands of ... 775 Liver . 74° Lobule of ear . . . . • 634 pneumo-gastric . . . 5*6 Lobules of the liver . . -744 testicle . . .781 Lobus caudatus . . ■ -743 quadratus .... 743 Spigelii 743 Lobe, central S°3 cuneus 5°5 frontal 5°2 occipital .... 503 parietal 5°2 quadrate .... 505 temporal .... 503 temporo-sphenoidal . • 5°3 Lobes of brain 5QI cerebellum . . • 5I6 Locus niger 524 perforatus . . ■ 498> 499 Lumbar fascia . . . . . 291 regions .... 697 Lungs 686 Lunula 68 Lymph 6 Lymph corpuscles .... 7 Lymph sinus 54 Lymphatic glands and vessels 51, 53 axillary 476 bronchial .... 48°! 692 cardiac 480 cervical 474 concatenate 475 head and neck . . • -474 heart 480 iliac 48° inguinal 477 832 PAGE Membrane, Demour, of ; Desccmet, of ... 623 hyaloid .... 631 Jacob’s .... 629 Nasmyth’s . . . 714 Reissner, of . . . 649 Schneiderian . . 614 Shrapnell, of . . 638 ventricles, of the . . 524 Membranous labyrinth . . . 646 urethra . . 1 777 Mesenteric glands . . . .481 Mesentery 701 Meso-colon 701 Meso-rectum 701 Mesosternum 132 Metacarpus 151 Metasternum 132 Metatarsus 172 Milk, secretion of ... 799 Mitosis 3 Mitral valve 667 Modiolus 645 Moll, glands of . . . . 618 Monro, foramen of . . . 509, 514 Mons Veneris . . . • ■ 795 Morgani, sinus of . . .261 Morsus diaboli 791 Motorial end plates .... 41 Mouth ...... 703 Movements of ankle-joint . . 221 atlas . . .188 axis . . . .188 clavicle . . .198 elbow-joint . . 204 hip-joint . . . 212 joints . . . 180 knee-joint . . 217 lower jaw . .190 occipital bone . . 188 phalanges of hand . 210 radius and ulna . 205 ribs . . . .192 scapula . . . 200 shoulder-joint. . 202 spine . . .184 wrist-joint . . 208 Mucous membrane, structure . 39 tissue 13 Multipolar cells . . . Muscles : arrangement of . . . . 227 lion-striated .... 31 striated 28 structure of .... 28 abdomen, of the .... 284 abductor indicis . . . .342 minimi digiti . 339, 373 liallucis .... 372 pollicis .... 338 accelerator urina).... 305 accessorii 240 accessorius .... 275, 374 adductor bl-evis .... 360 longus . . . .339 magnus .... 360 minimi digiti . . 342 INDEX. Muscles—continued. page adductor liallucis . . 375 pollicis .... 339 anconeus 335 anomalus 239 anti-tragicus .... 635 arytenoideus .... 679 aryteno-epiglottideus . . . 680 attollens auriculam . . . 233 attrahens auriculam . . . 233 auricularis 334 azygos uvute . . . .264 back, of the 269 basio-glossus 257 biceps flexor cruris . . .361 cubiti . . . 325 biventer cervicis .... 277 bracliialis anticus .... 325 buccinator 245 bulbo-cavernosus .... 305 eerato-glossus .... 257 cervicalis ascendens . . . 275 descendens . . . 275 cliondro-glossus . . . .257 ciliary of eye-ball .... 627 orbicularis palpebrarum 231 Riolan, of . . . 231, 617 circular, of Muller . . . 627 circumflexus palati . . . 264 cleido-occipital .... 249 cleido-mastoid .... 249 coccygeus .... 306, 310 complexus 276 compressor nasi .... 239 urethra) . . 306, 310 vesicuhe seminalis . 771 constrictor isthmi faucium . . 264 of pharynx, inferior . 260 middle . 260 superior 261 coraco-brachialis .... 324 corrugator supercilii . . . 232 cremaster 28g crico-arytenoideus lateralis . . 679 posticus. . 679 crico-thyroid .... 679 crureus 356 cucullaris 26g deltoid 323 depressor ala) nasi . . . 239 anguli oris . . .242 labii inferioris . . 242 detrusor urinse .... 766 diaphragm 299 digastricus ..... 254 dilatator naris .... 239 tuba) .... 642 erector clitoridis . . . .309 penis . . . .305 spmse «... 275 erectores pili . . . .70 extensor carpi radialis . . .322 ulnaris . . .335 coccygis . . . .279 digiti minimi . -334 digitorum brevis . . 37i digitorum communis . 334 digitorum longus . . 364 INDEX. 833 Muscles- eont tinted. page extensor indicis . . . . 337 ossis metacarpi pollicis 336 pollicis internodii. . 336 hallucis proprius . . 365 face, of the 229 flexor accessorius .... 374 brevis digiti minimi . 340, 375 carpi radialis . . . 328 ulnaris . . . 330 digitorum brevis . . 373 profundus. . 330 sublimis . . 329 longus digitorum pedis . 368 longus pollicis . . -331 ossis metacarpi min. dig. . 340 metacarpi pollicis . 338 pollicis brevis . . . 338 hallucis longus . . . 368 gastrocnemius .... 366 gemellus .... 350, 351 genio-hyo-glossus .... 256 genio-hyoid 255 gluteus maximus .... 349 medius .... 349 minimus .... 350 gracilis 360 helicis major .... 635 minor .... 635 head, of the 229 Horner’s 232 hyo-epiglottideus .... 680 hyo-glossus 256 iliacus internus . . . -357 ilio-costalis 275 indicator 337 infra-spinatus .... 321 intercostals 281 interossei . . . 341, 371, 376 interspinales .... 279 intertransversales . . . 279 ischio-cavernosus .... 305 larynx, of the .... 679 latissimus dorsi .... 271 levator al;e nasi .... 239 anguli oris . . . 241 scapulte. . . 272 ani .... 308, 310 glandulse thyroidese . 686 labii inferioris . . . 243 superioris . . 241 menti .... 243 palati .... 263 palpebrse superioris. . 234 prostati .... 308 levatores costarum . . . 283 lingualis . . . • • 257 longissimus dorsi .... 275 longus colli 268 lower extremity .... 343 lumbricales .... 341, 374 masseter 243 motor uvula: ..... 264 multifidus spina; . . . -279 mylo-hyoid 254 naso-labialis 240 neck, of the . . . • • 247 nutator capitis . . . .250 Muscles—continued. page obliquus abdominis . . 288, 289 auris .... 635 capitis .... 278 oculi .... 235 obturator .... 350, 351 occipito-frontalis .... 229 omo-hyoid . . . . 253 opponens digiti minimi . . 340 pollicis .... 338 orbicularis oris .... 240 palpebrarum . .231 palato-glossus . . . 258, 264 palato-pharyngeus . . 262, 264 palmaris brevis .... 339 longus .... 328 patientire 272 pectineus 359 pectoralis major .... 317 minor .... 318 perineum, of the .... 302 peroneus brevis .... 370 longus .... 370 tertius .... 364 plantaris . . . • • 366 platysma myoides . . . 247 popliteus 367 pronator quadratus . . . 332 radii teres . . . 327 psoas magnus .... 358 parvus 298 pterygoideus . . . . 245 pyramidalis abdominis . . 292 nasi .... 238 pyriformis 350 quadratus femoris . . 352 lumborum . . . 298 menti .... 242 quadriceps extensor . . . 357 rectus abdominis .... 292 capitis anticus . . . 266 lateralis . . . 278 posticus . . . 277 femoris . . . -354 oculi externus . . . 235 inferior . . . 234 internus . . . 235 superior . . . 234 retrahens auriculam . . . 233 lhomboideus major et minor . 272 risorius Santorini .... 242 rotatores spina: .... 279 sacro-coccygeus posticus . . 279 lumbalis . . . , 275 salpingo-pharyngeus . . . 262 sartorius 353 scalenus anticus .... 267 medius .... 267 posticus .... 268 semi-spinalis dorsi et colli . . 277 semi-membranosus . . . 362 semi-tendinosus .... 361 serratus magnus .... 319 posticus .... 273 soleus 367 sphincter ani . . . 307, 310 vaginas .... 309 vesica: .... 767 834 INDEX. Muscles—continued. page spinalis dorsi .... 275 splenius 274 stapedius 641 sterno-hyoid . . . * . 252 mastoid .... 249 occipital .... 249 thyroid .... 252 stylo-glossus 258 hyoid 254 pharyngeus . . . .262 subanconeus 327 subclavius 319 subcostals 282 sub-crureus 357 subscapularis .... 320 supinator brevis .... 335 longus .... 333 supra-spinatus .... 320 temporal 244 tensor palati 264 tarsi 232 tympani . . . .641 vagina; femoris . . . 353 teres major 321 minor 321 thorax, of the . . . .281 thyro-arytenoideus . . . 680 thyro-epiglottoideus . . . 680 hyoid 253 tibialis anticus .... 363 posticus .... 369 trachelo-mastoid .... 276 tragicus 635 transversalis abdominis . . 291 cervicis . . . 276 transversus auricula; . . . 635 pedis . . .375 perinei . . 306, 309 trapezius 269 triangularis oris .... 242 sterni. . . . 282 triceps brachii .... 326 extensor femoris . 357 cubiti . . 326 trochlearis 235 upper extremity, of the . . 315 ureters, of the .... 729 vastus externus .... 355 internus . . . .355 Wilson’s 307 zygomatic 241 Muscle 27 striated 28 non-striated . . .31 of heart .... 31 rods 29 Musculi papillares . . . 665, 667 pectinati . . . 663, 666 Myeloplaxes 24 Myolemma 28 Myology . . . 227 Naboth, ovula of ... 700 Nails 68 Nares i3o Nasal duct 621 fossa; .... 129, 613 PAGE Nasion 528 Nasmyth, membrane of . . . 714 Nates cerebri 514 Nerve endings, motor ... 41 sensory . . -39 Nerve cells 35 fibres 33 terminations .... 39 Nerves: general anatomy . . 32, 38 abducentes 547 accessorius ..... 559 acromial . . . . . 566 Arnold’s 556 auditory .... 551, 651 auricularis inferior . . . 546 magnus . . . 566 posterior . . . 549 superior . . . 546 vagi . . . .556 auriculo-temporal . . . 546 brachial 568 buccal ..... 545, 551 cardiac .... 558, 604, 672 carotid 555 cervical . . . . . . 564 cervico-facial . . . .551 chorda tympani . . . 549, 643 ciliary 543, 626 circumflex 5771 clavicular 566 coccygeal 589 cochlear 551, 652 communicans cervicis . . . 566 peronei . . . 596 poplitei . . . 593 tibialis . . . 593 cranial 536 crural 585 cutaneus externus, brachialis . 571 femoris . . 596 internus, brachialis . 572 femoris . . 585 medius, femoris . . 585 lateralis . . . 579 patella; .... 587 spiralis . . . 576 dental 544, 546 descendens cervicis . - . .561 digastric 550 dorsal 578 dorsalis penis .... 591 eighth pair . . . . ■. 551 eleventh pair .... 559 facial 548 fifth pair 539 first pair 536 fourth pair . . . . 539 frontal . . . , . . . 540 gastric 727 genito-crural 583 glosso-pharyngeal. . . 553, 656 gluteal . . . . . . 590 inferior .... 590 gustatory .... 547, 655 hamiorrhoidal .... 591 hypoglossal .... 560, 656 INDEX. 835 Nerves—continued. page ilio-hypogastric . . . .581 ilio-inguinal 582 inferior maxillary. . . 545 infra-maxillary . . . .551 infra-orbital 543 infra-trochlear .... 543 intercostal 578 intercosto-humeral . . . 580 interosseous, anterior . . . 573 posterior . . 577 ischiatic greater .... 592 lesser . . . .591 Jacobson’s .... 533, 643 labial 545 lachrymal 541 laryngeal, external . . . 557 inferior . . 558, 684 recurrent . . 558, 684 superior . . 557, 684 lingual 547, 562 lumbar 581 lumbo-sacral 587 malar 544, 551 mammae 790 masseteric 545 maxillaris, inferior . . . 545 superior . . . 543 median . . . . . 572 mental 547 molles 603 motores oculorum . . . 538 musculo-cutaneous, arm . . 571 leg . . 596 musculo-spiral .... 575 mylo-hyoid 546 nasal .... 542, 399, 615 naso-palatine .... 599 ninth pair 533 obturator 583 occipitalis major .... 568 minor .... 566 oesophageal 558 olfactory 536 ophthalmic 540 optic 537 orbital 543 palatine 599 palmar . . . . . 573, 575 pathetici 539 perforans Casserii . . .571 perineal 591 peroneal 595 petrosal 600 pharyngeal .... 555, 556 phrenic . . . . . 567 plantar 594 pneumogastric .... 555 popliteal .... 593, 595 portio dura 548 intermedia.... 548 mollis 548 pterygoid .... 546, 600 pterygo-palatine .... 600 pudendal, inferior . . . 392 pudic 591 pulmonary 558 radial 577 Nerves—continued. page recurrent 558 renal 608, 764 respiratory, external . . -570 ' internal . . . 567 rhomboid 570 sacral 588 saphenous, external . . . 593 long or internal . 587 short . . . 593 second pair 537 seventh pair ..... 548 sixth pair 547 spheno-palatine .... 544 spinal 562 spinal accessory .... 559 splanchnic 608 sternal 566 stylo-hyoid 550 subclavian 571 suboccipital .... <567 subrufi 603 subscapular 571 superftcialis colli .... 565 cordis . . . 604 superior maxillary . . . 543 supra-maxillary .... 551 supra-orbital .... 540 supra-scapular .... 571 supra-trochlear . . . .541 sympathetic .... 41, 597 temporal . . 543, 545, 546, 551 temporo-facial .... 550 temporo-malar .... 543 tenth pair 555 third pair 538 thoracic 607 thyro-hyoid 561 tibial anterior .... 596 posterior .... 593 tonsilitic 555 trifacial 539 trigeminus 539 trochlearis 539 twelfth pair 560 tympanic . . . 549, 553, 643 ulnar 574 uterine 790 vagus 555 vesical 768 vestibular .... 55*1 652 Yidian 600 Wrisberg, of 572 Neural canal 73 Neurolemma 33 Neuroglia 37, /88 Neurology 485 Nidus hirundinis . . . .517 Nipple 798 Nodes of Ranvier .... 34 Nodule 517 Nose 611 Nuck, canal of 795 Nucleolus of cells .... 3 Nucleus, caudatus .... 522 cuneatus .... 494 gracilis .... 494 emboliformis , . . 518 836 INDEX, PAGE Nucleus, fastigii . . . .518 globosus . . . .518 lenticularis . . . 523 of cells .... 3 olivary .... 495 teniaformis . . . 523 Nymph® 796 Obex 520 Obturator foramen .... 157 Odontoblasts 718 (Esophagus 722 Olivary body 491 fasciculus .... 492 nucleus .... 494 Omentum, gastro-colic . . .701 gastro-hepatic . . 700 gastro-splenic . . 702 great . . . .701 lesser .... 700 Operculum .... 501, 503 Optic commissure .... 538 thalami .... 508, 513 Ora serrata 627 Orbiculare, os 640 Orbits 127 Organ of Corti 649 Gir aides .... 783 Rosenmtiller . . . 792 Os tine® 788 Ossicula auditus .... 638 Ossification 24 Osteoblasts . . . . 21, 24 Osteoclasts 27 Osteodentine 715 Osteology 73 Ostium abdominale .... 791 uterinum . . . -791 Otoconia (47 Otoliths 647 Ovaries 792 Oviducts 791 Ovisacs 793 Ovula of Naboth .... 790 Ovum 794 Pacchionian bodies . . . 454, 530 Pacinian corpuscles ... 39 Palate 703 Palmar arch 416 Palpebr® 616 Palpebral ligament . . . .617 Pancreas 751 Papill® of the nail .... 68 skin ... 64 tongue . . . 654 calyciformes . . . 654 circumvallat® . . .654 filiform .... 654 fungiform .... 655 Paraglobulin 6 Parepididymis 783 Par ovarium 792 Parotid gland 707 Pedunculi cerebri .... 499 Pelvis . . . . . 158, 765 viscera of .... 765 PAGE Penis . . 771 Perforating fibres of bone . . 21 Pericardium .... 658, 671 Perichondrium 19 Perilymph 646 Perimysium 28 Perineurium 38 Perineum, muscles of . . 302, 308 Periosteum 21 Peritoneum 697 Perspiratory ducts .... 72 Pes accessorius . . . .511 anserinus 548 hippocampi . . . .511 Petit, canal of 633 Peyer’s glands 734 Phalanges 153 Pharynx 720 Pia mater 533, 535 Pigment 16 Pillars of the abdominal ring . . 288 diaphragm . . . 292 palate . . . 705 Pineal body . . . . 515 Pinna 633 Pituitary body .... 499 membrane . . 614 Plasma 6 Pleura 693 Plexus, Auerbach, of 735 general anatomy... 39 aortic 609 axillary .... 568 brachial .... 568 cardiac .... 604 carotid .... 602 cavernous .... 602 cervical .... 565 choroid .... 508 coronary .... 606 diaphragmatic . . . 608 epigastric .... 608 gastric 608 gul® 558 htemorrhoidal . . . 610 hepatic .... 608 hypogastric .... 609 lumbar .... 581 maxillary . . . 544, 546 Meissner, of 735 mesenteric .... 609 myentericu8 . . . 735 (esophageal .... 558 patellar .... 587 pharyngeal . . . 555, 557 phrenic .... 608 prostatic . . . 466, 610 pterygoid 451 pulmonary 438 renal 608 sacral 589 solar 608 spermatic .... 609 splenic .... 608 supra-renal . . . 608, 757 tonsilitic .... 555 tympanic . . . 553, 643 837 PAGE Plexus, uterine.... 466, 610 vaginal 610 vertebral .... 604 vesical . . . 466, 610, 768 Plica; palmata; 79° Pneumo-gastric lobule . . .516 Pomum Adami 675 Pons Tarini 499 Varolii 496 Pores 67 Portal vein .... 473, 746 Portio dura 548 mollis 548 Porus opticus 622 Poupart’s ligament . . . 288 Prepuce 772 Presternum 132 Prickle cells 8 Processus e cerebello ad testes . 520 vermiformis . . ■ Promontory 638 Prostate gland 769 Prostatic urethra .... 776 Protoplasm 1 Primitive sheath 33 Pseudo-podia 2 Pseudo-stomata 57 Pulmonary artery . . . 449> 665 plexuses . . 558, 692 sinuses . . . • 665 veins . . . 473, 666 Pulvinar 5!3 Puncta lachrymalia . . . 617, 620 vasculosa .... 506 Pupil 625 Purkinje, cells of . . ■ 518 Pylorus 723 Pyramid 5[7) 638 Pyramids, anterior .... 491 decussation of . . 491 Malpighi, of . . • 759 posterior.... 493 Quadrate lobe .... 5°5i 7°7 Ranvier, nodes of . . • -34 Raphe corporis callosi . . . 5°7 Receptaculum chyli . . . 48z Rectum 737 Red corpuscles .... 5 Regions, abdominal . . -697 Reil, island of 5°3 fissures of . . • • 5°3 Reissner, membrane of . . . 649 Remak, fibres of . . • • 34 Respiratory muscles . . .283 Restiform bodies .... 492 Reticular tissue .. - ■ ■ 16 Rete mucosum .... 65 testis 781 Retina 627 Ribes, ganglion of . . . .602 Ribs *33 Rima glottidis 682 Ring, external abdominal . . 288 femoral 345 INDEX. PAGE Ring, internal abdominal . . 295 Riviniau ducts . . . .708 recess .... 636 Rods of Corti 649 retina 629 Rolando, fissure of . . • 5OI> 529 funiculus of 493 tubercle of 493 Roots of spinal nerves . . . 490 Rosenmiiller, accessory gland of . 620 organ of 792 fossa of 721 Ruga; 725 Ruysch, tunic of ... 624 Sacculus communis . . . -647 laryngis . . . .683 proprius .... 647 Salivary glands . . . • 7°7 Saphenous opening . . . -344 Saphena veins 463 Sarcolemma 28 Sarcous elements .... 29 Scala tympani 646 vestibuli 646 Scarf-skin 64 Scarpa, space of . . . -354 Schindylesis 179 Schneiderian membrane . . . 614 Schwann, white matter of . . 33 Sclerotic coat 621 Scrotum 778 Sebaceous glands .... 70 Semicircular canals .... 644 Semilunar fibro-cartilages . . 216 valves . . . 665, 668 Sense, organs of . . . .611 Septum crurale . . . • 346 lucidum . . . .511 interventricular . . . 668 pectiniforme . . . 772 posticum . . . -535 scroti 778 Serous membrane, structure . . 56 Serum 6 Sesamoid bones . . . • 174 Sheath of arteries .... 47 rectus .... 293 Shrapnell, membrane of . . . 638 Sigmoid valves . . . 663, 668 Sinus pocularis . . • • 776 venosus 660 Sinuses, structure . . . - 51 aortic . . • 377> 668 basilar .... 455 cavernous .... 456 circular .... 455 coronary . . . . 471 lateral .... 456 longitudinal, inferior . 455 superior . 454 occipital . . . -455 petrosal, inferior . . 457 superior . . 457 pulmonary .... 665 spheno-parietal . . . 458 838 INDEX. PAGE Sinuses, straight .... 455 transverse . . . .455 uterine .... 790 Valsalva, of . 377, 665, 668 Skein 3 Skeleton 73 Skene, tubules of ... 786 Skin . . . . . . .63 Skull 87 Socia parotidis 707 Soft palate 705 Spaces of Fontana .... 624 Spermatic canal .... 295 cord .... 778 Spheno-maxillary fossa . . .128 Splieno-palatine ganglion . . 599 Spheroidal epithelium ... 9 Spigelius, lobule of . . . . 743 Spinal cord 485 nerves .... 490, 562 veins 469 Spleen 753 Splenium corporis callosi . . 507 Spongio-plasm 2 Spongy part of the urethra . . 777 Squamous epithelium ... 8 Stapes 640 Stenson’s duct 707 Stephanion 528 Stilling, canal of ... 631 Stomach 723 Stomata 11 Stratum Malpighi .... 65 Stria terminalis .... 508 Striaj acusticse 520 longitudinales . . . 507 muscular .... 28 Sub-arachnoid fluid . . . 533, 535 space . . 533, 535 Sublingual gland .... 708 Submaxillary gland .... 707 Substantia cinerea . . . . 488 perforata . . . 498 Sudoriferous ducts .... 72 glands. . . .71 Sulci of the brain . . . .501 Supercilia 616 Superficial fascia . . . .228 Supra-renal bodies .... 756 Suspensory ligament, liver . .741 penis . . 77s Sutures 120 Sylvius, aqueduct of . .514 fissure of . . . .501 Sympathetic ganglia ... 37 nerve .... 41 system . . 41, 597 Symphysis " 179 Synarthrosis .... 175, 178 Synovial membranes . ■ • 57 Tactile corpuscles .... 67 Tapetum 629 Tarsal plates 617 Tarsus 167 Teeth ...... 709 Tela choroidea 513 PAGE Temporal fossa . . . .122 Tendo-Achillis 366 oculi 231 Tendon 14 Tenon, capsule of . . 236, 615, 621 Tenia hippocampi . . . .511 semicircularis . . . 508 Tentorium cerebelli . . .531 Tesselated epithelium ... 8 Testes cerebri 514 Testicles 778 descent .... 784 Thalami optici .... 508, 513 Thebesian valve .... 662 Thecas 329 Thoracic duct 482 Thorax ..... 136, 657 Thymus body 695 Thyro-hyoid membrane . . . 677 Thyroid axis . . . . 403 cartilage .... 675 foramen . . . .157 body 685 Tissue, yellow fibrous ... 14 elastic 14 Tongue 652, 704 Tonsils 705 of cerebellum . . .516 Torcular Heropliili .... 455 Trachea 684 Tractus opticus .... 537 spiralis . . . .651 Tragus 634 Transitional epithelium ... 9 Triangle of Hesselbach . . . 435 Triangles of the neck . . .251 Triangular ligament . . .304 Tricuspid valve .... 663 Trigonum vesicae .... 767 habenulae . . .514 Trochanter major et minor . 160, 161 Trochoides 180 Trochlea I42 Trochlearis 235 Tuber cinereum .... 499 Tuberculum acusticum . . .520 Tuber vallae 5i7 Tubercle of Lower . . . . 663 Tubuli seminiferi .... 781 uriniferi .... 760 Tulpius, valve of ... 739 Tunica albuginea oculi . . . 235 testis . . . 780 erythroides . . . .779 Ruysehiana .... 624 vaginalis 780 oculi . 236, 615, 621 vasculosa testis . . .781 Tutamina oculi .... 616 Tympanic bone .... 99 Tympanum 637 Tyson’s glands 771 Umbo 638 Umbilical region .... 697 Urachus 766 Ureter 764 INDEX. 839 PAGE Urethra, female .... 785 male 774 Uterus 787 Utricle 647 Uvea 625 Uvula cerebelli . . . .517 palati 705 vesicse 767 Vagina 786 Vallecula 5l6 Valsalva, sinuses of. . 377, 665, 668 Valve, Bauhin, of ... 739 coronary .... 662 Eustachian . . . . 661 Foltz, of ... 620 Hasner, of . . . . 621 Huschke, of . . . 620 ileo-ca;oal .... 739 mitral 667 pyloric 726 rectum, of the . . . 739 semi-lunar . . . 665, 668 tricuspid .... 663 Tulpius 739 Vieussens, of ... 520 Valves of Kerkring .... 730 veins .... 50 Valvuhe conniventes . . 730 Vasa afferentia . . -53, 763 efferentia . . -53! 763, 781 pampiniformia .... 778 recta 781 vasorum 47 vorticosa 624 Vasculum aberrans .... 783 Vas deferens 783 Vater, corpuscles of ... 39 Veins : 49 structure 50 angular . 450 auricular 451 axillary 461 azygos 468 basilar 453 basilic 460 basis vertebrarum . . . 470 brachio-cephalic .... 464 bronchial 469 cardiac 47° cava, inferior .... 464 superior .... 463 cephalic 46° cerebellar 454 cerebral 453 comites . . 49, 460, 462 coronary 471 corporis striati . . . 453, 508 diploe 452 dorsal of penis .... 466 dorsi-spinal 469 emissary 452 emulgent 467 facial 45° femoral 462 frontal 45° Galeni 453> 5*3 Veins—continued. page gastric 472 hsemorrhoidal .... 466 hepatic 467, 748 iliac 466 innominate 464 intercostal 468 jugular 458 lumbar 467 mammary 464 mastoid 452 maxillary internal . . • 451 median 461 basilic .... 461 cephalic .... 461 medulli-spinal .... 470 meningo-raehidian . . 469 mesenteric . . . . ■ 471 occipital 451 ophthalmic . ... • • 458 ovarian 467 parietal 454 phrenic 467 popliteal 462 portal 473, 746 profunda femoris .... 462 prostatic 466 pulmonary 473 radial 460 renal 467, 763 salvatella 46° saphena 463 spermatic 467 spinal 469 splenic 472 subclavian 461 supra-renal 467 temporal 451 temporo-maxillary . . . 451 Thebesii 471 thymic 696 thyroid 459 ulnar 460 umbilical 673 uterine 466 vena cava 463 vertebral .... 459, 469 vesical 466, 768 Velum interpositum . . .513 medullare . . . .517 pendulum palati . . . 705 Vense comites . . 49, 460, 462 Galeni .... 453, 513 Thebesii 471 vorticosse .... 624 Ventricles of the brain—fifth . . 511 fourth . 519 lateral . 508 third . 514 corpus callosum . 506 heart . . 663, 666 larynx . . . 683 Vermiform process .... 735 Vermis of cerebellum . . -517 Vertebra, characters of . . -75 Vertebral column .... 74 Veru montanum .... 776 Vesiculse seminalis .... 770 840 INDEX. PAGE Vestibule 644 Vestibulum vagina; .... 797 Vibrissa; 611 Vieussens, valve of . . . .520 Villi „2 Vincula accessoria .... 329 Vitreous humour .... 631 Voluntary muscle .... 28 Vulva 796 Wander cells Wharton’s duct .... 704 White corpuscles .... 5 Willis, circle of .... 402 Wilson’s muscles .... 307 Winslow, foramen of 700 Wirsung, duct of . . .752 Worm of cerebellum . . 516 PAGE Wormian bones .... 120 Wrisberg, nerve of . . . . 572 Xiphoid process . . . .132 Y-shaped ligament . . . .211 Yellow fibrous tissue ... 14 spot ..... 630 Zona fasciculata .... 756 glomerulosa .... 756 pellucida 794 reticularis .... 756 Zonula ciliaris 632 of Zinn 632 Zygoma 95 Zygomatic fossa . . . .122 THE END. PRINTED BY BALLANTYNK, HANSON AND CO. EDINBURGH AND LONDON CATALOGUE No. 7. SEPTEMBER, 1892. A CATALOGUE OF Books for Students. INCLUDING THE ? QUIZ-COMPENDS ? PAGE New Series of Manuals, 2,3,4,5 Anatomy, . . . . 6 Biology, . . . .11 Chemistry, . . . . 6 Children’s Diseases, . . 7 Dentistry, . ... 8 Dictionaries, . . 8, 16 Eye Diseases, . . .8 Electricity, . ... 9 Gynaecology, . . .10 Hygiene, .... 9 Materia Medica, . . .9 Medical Jurisprudence, . xo Nervous Diseases, . . 10 CONTENTS. FAGK Obstetrics 10 Pathology, Histology,. . n Pharmacy 12 Physical Diagnosis, . .11 Physiology, . . . .11 Practice of Medicine, . n, 12 Prescription Books, . . 12 ?Quiz-Compends ? . 14,15 Skin Diseases, . . .12 Surgery and Bandaging, . 13 Therapeutics, . . ,9 Urine and Urinary Organs, 13 Venereal Diseases, . .13 PUBLISHED BY P. BLAKISTON, SON & CO., Medical Booksellers> Importers and Publishers. LARGE STOCK OF ALL STUDENTS’ BOOKS, AT THE LOWEST PRICES. 1012 Walnut Street, Philadelphia. *** For sale by all Booksellers, or any book will be sent by mail, postpaid, upon receipt of price. 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A manual of Dissection of the Human Body. Fifth Edition. Enlarged, with Marginal References and over 200 Illustrations. Octavo. Bound in Oilcloth, for the Dissecting Room, $4.50. Holden’s Human Osteology. Comprising a Description of the Bones, with Colored Delineations of the Attachments of the Muscles. The General and Microscopical Structure of Bone and its Development. With Lithographic Plates and Numerous Illus- trations. Seventh Edition. 8vo. Cloth, 6.00 Holden’s Landmarks, Medical and Surgical. 4th ed. Clo., 1.25 Potter’s Compend of Anatomy. Fifth Edition. Enlarged. 16 Lithographic Plates. 117 Illustrations. See Page 14. Cloth, 1.00; Interleaved for Notes, 1.25 CHEMISTRY. Bartley’s Medical Chemistry. Second Edition. A text-book prepared specially for Medical, Pharmaceutical, and Dental Stu- dents. With 50 Illustrations, Plate of Absorption Spectra and Glossary of Chemical Terms. Revised and Enlarged. Cloth, 2.50 Trimble. Practical and Analytical Chemistry. 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Including Urinary Analysis. Third Edition. Revised. See page ij- Cloth, 1.00; Interleaved for Notes, 1.25 Leffmann and Beam. Progressive Exercises in Practical Chemistry. i2mo. Illustrated. Cloth, 1.00 Muter. Practical and Analytical Chemistry. Fourth Edi- tion. Revised, to meet the requirements of American Medical Colleges, by Prof. C. C. Hamilton. Illustrated. Cloth, 2.00 Holland. The Urine, Common Poisons, and Milk Analysis, Chemical and Microscopical. For Laboratory Use. Fourth Edition, Enlarged. Illustrated. Cloth, 1.00 Van Nuys. Urine Analysis. Illus. Cloth, 2.00 Goodhart and Starr. The Diseases of Children. Second Edition. By J. F. Goodhart, m.d., Physician to the Evelina Hospital for Children; Assistant Physician to Guy's Hospital, London. Revised and Edited by Louis Starr, m.d., Clinical Professor of Diseases of Children in the Hospital of the Univer- sity of Pennsylvania; Physician to the Children s Hospital, Philadelphia. Containing many Prescriptions and Formula:, conforming to the U. S. Pharmacopoeia, Directions for making Artificial Human Milk, for the Artificial Digestion of Milk, etc. Illustrated. Cloth, 3.00; Leather, 3.50 Hatfield. Diseases of Children. By M. P. Hatfield, m.d., Professor of Diseases of Children, Chicago Medical College. Colored Plate. i2mo. Cloth, 1.00; Interleaved, 1.25 Starr. Diseases of the Digestive Organs in Infancy and Childhood. With chapters on the Investigation of Disease, and on the General Management of Children. By Louis Starr, m.d., Clinical Professor of Diseases of Children in the Univer- sity of Pennsylvania. Illus. Second Edition. Cloth, 2.25 4®“ See pages 14 and IS for list of? Quiz- Comp ends ? CHILDREN. 8 STUDENTS' TEXT-BOOKS AND MANUALS. DENTISTRY. Fillebrown. Operative Dentistry. 330 Illus. Cloth, 2.50 Flagg’s Plastics and Plastic Filling. 4th Ed. Cloth, 4.00 Gorgas. Dental Medicine. Fourth Edition. Cloth, 3.50 Harris. Principles and Practice of Dentistry. Including Anatomy, Physiology, Pathology, Therapeutics, Dental Surgery and Mechanism. Twelfth Edition. Revised and enlarged by Professor Gorgas. 1028 Illustrations. Cloth, 7.00 ; Leather, 8.00 Richardson’s Mechanical Dentistry. Fifth Edition. 569 Illustrations. 8vo. Cloth, 4.50; Leather, 5.50 Sewill. Dental Surgery. 200 Illustrations. 3d Ed. Clo., 3.00 Taft’s Operative Dentistry. Dental Students and Practitioners. Fourth Edition. 100 Illustrations. Cloth, 4.25 ; Leather, 5.00 Talbot. Irregularities of the Teeth, and their Treatment. Illustrated. 8vo. Second Edition. Cloth, 3.00 Tomes’ Dental Anatomy. Third Ed. 191 Illus. Cloth, 4.00 Tomes’ Dental Surgery. 3d Edition. 292 Illus. Cloth, 5.00 Warren. Compend of Dental Pathology and Dental Medi- cine. Illustrated. Cloth, 1.00; Interleaved, 1.25 Gould’s New Medical Dictionary. Containing the Definition and Pronunciation of all words in Medicine, with many useful Tables etc. Dark Leather, 3.25; % Mor., Thumb Index, 4.25 Gould’s Pocket Dictionary. 12,000 Medical Words Pro- nounced and Defined. Containing many Tables and an Elaborate Dose List. Thin 64010. Just Ready. Cloth, 1.00; Leather, 1.25 Harris’ Dictionary of Dentistry. Fifth Edition. Completely revised by Prof. Gorgas. Cloth, 5.00; Leather, 6.00 Cleaveland’s Pronouncing Pocket Medical Lexicon. Small pocket size. Cloth, red edges .75 ; pocket-book style, 1.00 Longley’s Pocket Dictionary. The Student's Medical Lexicon, giving Definition and Pronunciation, with an Appendix giving Abbreviations used in Prescriptions, Metric Scale of Doses, etc. 24U10. Cloth, 1.00; pocket-book style, 1.25 DICTIONARIES. Hartridge on Refraction. 5th Edition. Ulus. Cloth, 2.00 Swanzy. Diseases of the Eye and their Treatment. 176 Illustrations. Fourth Edition. Cloth, 300; Leather, 3.50 Fox and Gould. Compend of Diseases of the Eye and Refraction. 2d Ed. Enlarged. 71 Illus. 39 Formulae. Cloth, 1.00 ; Interleaved for Notes, 1.25 See pages 2 to 5 for list of Students' Manuals. EYE. STUDENTS’ TEXT-BOOKS AND MANUALS. ELECTRICITY. Bigelow. Plain Talks on Medical Electricity. Cloth, 1.00 Mason’s Compend of Medical Electricity. Cloth, 1.00 Steavenson and Jones. Medical Electricity. A Practical Handbook. Just Ready. Illustrated. i2mo. Cloth, 2.50 HYGIENE. Coplin and Bevan. Practical Hygiene. By W. M. L. Cop- lin, Adjunct Professor of Hygiene, Jefferson Medical College, Philadelphia, and Dr. D. Bevan. Illustrated. In Press. Parkes’ (Ed. A.) Practical Hygiene. Seventh Edition, en- larged. Illustrated. 8vo. Cloth, 4.50 Parkes’ (L. C.) Manual of Hygiene and Public Health. Second Edition. i2mo. Cloth, 2.50 Wilson’s Handbook of Hygiene and Sanitary Science. Seventh Edition. Revised and Illustrated. Cloth, 3.23 MATERIA MEDICA AND THERAPEUTICS. Potter’s Compend of Materia Medica, Therapeutics, and Prescription Writing. Fifth Edition, revised and improved. See page rj. Cloth, 1.00; Interleaved for Notes, 1.25 Davis. Essentials of Materia Medica and Prescription Writing. By J. Aubrey Davis, m.d., Demonstrator of Obstet- rics and Quiz-Master on Materia Medica, University of Penn- sylvania. i2mo. Interleaved. Net, 1.50 Biddle’s Materia Medica. Eleventh Edition. By the late John B. Biddle, m.d. Revised by Clement Biddle, m.d., 8vo, illustrated. Cloth, 4.25; Leather, 5.00 Potter. Handbook of Materia Medica, Pharmacy, and Therapeutics. Including Action of Medicines, Special Thera- peutics, Pharmacology, etc. By Sami. O. L. Potter, m.d., m.r.c.p. (Lond.), Professor of the Practice of Medicine in Cooper Medical College, San Francisco. Third Revised and Enlarged Edition. 8vo. Cloth, 4.00; Leather, 5.00 White and Wilcox. Materia Medica, Pharmacy, Phar- macology, and Therapeutics. A Handbook for Students. By Wm. Hale White, m.d., f.r c.p., etc., Physician to and Lecturer on Materia Medica, Guy’s Hospital. Revised by Reynold W. Wilcox, m.d., Professor of Clinical Medicine at the New York Post Graduate Medical School, Assistant Physician Bellevue Hospital, etc. American Edition. Clo., 3.00; Lea., 3.50 JK3~ See pages 14 and 15 for list of f Quiz-Compends I 10 STUDENTS’ TEXT-BOOKS AND MANUALS. MEDICAL JURISPRUDENCE. Reese. A Text-book of Medical Jurisprudence and Toxi- cology. By John J. Reese, m.d., Professor of Medical Juris- prudence and Toxicology in the Medical Department of the University of Pennsylvania; Physician to St. Joseph’s Hospital. Third Edition. Cloth, 3.00; Leather, 3.50 Gowers. Manual of Diseases of the Nervous System. A Complete Text-book. By William R. Gowers, m.d., Prof. Clinical Medicine, University College, London. Physician to National Hospital for the Paralyzed and Epileptic. Second Edition. Revised, Enlarged, and in many parts Rewritten. With many new Illustrations. Octavo. Vol. I. Diseases of the Nerves and Spinal Cord. 616 pages. Cloth, 3.50 Vol. II. Diseases of the Brain and Cranial Nerves. General and Functional Diseases. Nearly Ready. Ormerod. Diseases of Nervous System, Student’s Guide to. By J. A. Ormerod, m.d., Oxon., f.r.c.p. (London), Member Path- ological. Clinical, Ophthalmological, and Neurological Societies, Physician to National Hospital for Paralyzed and Epileptic and to City of London Hospital for Diseases of the Chest, Demon- strator of Morbid Anatomy, St. Bartholomew’s Hospital, etc. With 75 Wood Engravings. Cloth, 2.00 NERVOUS DISEASES. Davis. A Manual of Obstetrics. By Edw. P. Davis, Dem- onstrator of Obstetrics, Jefferson Medical College, Philadelphia. Colored Plates, and 130 other Illustrations. i2tno. Cloth, 2.00 Byford. Diseases of Women. The Practice of Medicine and Surgery, as applied to the Diseases and Accidents Incident to Women. By W. H. Byford, A.M., m.d., Professor of Gyna:cology in Rush Medical College and of Obstetrics in the Woman’s Med- ical College, etc., and Henry T. Byford, m.d., Surgeon to the Woman’s Hospital of Chicago. Fourth Edition. Revised and Enlarged. 306 Illustrations, over xoo of which are original. Octavo. 832 pages. Cloth, 5.00; Leather, 6.00 Lewers' Diseases of Women. A Practical Text-book. 139 Illustrations. Second Edition. Cloth, 2.50 Parvin’s Winckel’s Diseases of Women. Second Edition. Including a Section on Diseases of the Bladder and Urethra. 150 Illus. Revised. See J>age 3. Cloth, 3.00; Leather, 3.50 Morris. Compend of Gynaecology. Illustrated. Cloth, 1.00 Winckel’s Obstetrics. A Text-book on Midwifery, includ- ing the Diseases of Childbed. By Dr. F. Winckel, Professor of Gynaecology, and Director of the Royal University Clinic ior Women, in Munich. Authorized Translation, by J. Clifton Edgar, m.d., Lecturer on Obstetrics, University Medical Col- lege, New York, with nearly 200 handsome Illustrations, the majority of which are original. 8vo. Cloth, 6.00; Leather, 7.00 See pages 2 to 5 /or list of New Manuals. OBSTETRICS AND GYNAECOLOGY. STUDENTS’ TEXT-BOOKS AND MANUALS. 11 Obstetrics and Gyncecology :—Continued. Landis’ Compend of Obstetrics. Illustrated. 4th Edition, Enlarged. Cloth, 1.00; Interleaved for Notes, 1.25 Galabin’s Midwifery. By A. Lewis Galabin, m.d., f.r.c.p. 227 Illustrations. Seepages. Cloth, 3.00; Leather, 3.50 PATHOLOGY, HISTOLOGY, ETC. Wethered. Medical Microscopy. By Frank J. Wethered, m.d., m.r.c.p. 98 Illustrations. Cloth, 2.50 Bowlby. Surgical Pathology and Morbid Anatomy, for Students. 135 Illustrations. i2mo. Cloth, 2.00 Gilliam’s Essentials of Pathology. A Handbook for Students. 47 Illustrations. i2mo. Cloth, 2.00 Virchow’s Post-Mortem Examinations. 3d Ed. Cloth, 1.00 Fenwick. 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Cloth, 7.00 ; Leather, 8.00 “ With this Text-book at his command, no student could fail in his examination.”—Lancet. Sanderson’s Physiological Laboratory. Being Practical Ex- ercises for the Student. 350 Illustrations. 8vo. Cloth, 5.00 PRACTICE. Taylor. Practice of Medicine. A Manual. By Frederick Taylor, m.d., Physician to, and Lecturer on Medicine at, Guy’s Hospital, London ; Physician to Evelina Hospital for Sick Chil- dren, and Examiner in Materia Medica and Pharmaceutical Chemistry, University of London. Cloth, 2.00; Leather, 2.50 JKf See pages 14 and 15 for list of > Quiz-Compends f 12 STUDENTS’ TEXT-BOOKS AND MANUALS. Roberts' Practice. New Revised Edition. A Handbook of the Theory and Practice of Medicine. By Frederick T. Roberts, m.d., m.r.c.p., Professor of Clinical Medicine and Therapeutics in University College Hospital, London. Seventh Edition. Octavo. Cloth, 5.50 ; Sheep, 6.50 Hughes. Compend of the Practice of Medicine. 4th Edi- tion. Two parts, each, Cloth, 1.00; Interleaved for Notes, 1.25 Part i.—Continued, Eruptive and Periodical Fevers, Diseases of the Stomach, Intestines, Peritoneum, Biliary Passages, Liver, Kidneys, etc., and General Diseases, etc. Part ii.—Diseases of the Respiratory System, Circulatory System, and Nervous System; Diseases of the Blood, etc. Physicians’Edition. Fourth Edition. Including a Section on Skin Diseases. With Index. 1 vol. Full Morocco, Gilt, 2.50 From John A. Robinson, M.D., Assistant to Chair of Clinical Medicine, now Lecturer on Materia Medica, Rush Medical Col- lege, Chicago. “Meets with my hearty approbation as a substitute for the ordinary note books almost universally used by medical students. It is concise, accurate, well arranged, and lucid, . . . just the thing for students to use while studying physical diagnosis and the more practical departments of medicine.” Practice :— Continued. PRESCRIPTION BOOKS. Wythe’s Dose and Symptom Book. Containing the Doses and Uses of all the principal Articles of the Materia Medica, etc. Seventeenth Edition. Completely Revised and Rewritten. Just Ready. 32mo. Cloth, 1.00; Pocket-book style, 1.25 Pereira’s Physician’s Prescription Book. Containing Lists of Terms, Phrases, Contractions, and Abbreviations used in Prescriptions, Explanatory Notes, Grammatical Construction of Prescriptions, etc., etc. By Professor Jonathan Pereira, m.d. Sixteenth Edition. 32mo. Cloth, 1.00; Pocket-book style, 1.25 PHARMACY. Stewart’s Compend of Pharmacy. Based upon Remington's Text-book of Pharmacy. Third Edition, Revised. With new Tables, Index, Etc. Cloth, 1.00 ; Interleaved for Notes, 1.25 Robinson. Latin Grammar of Pharmacy and Medicine. By H. D. Robinson, ph.d., Professor of Latin Language and Literature, University of Kansas, Lawrence. With an Intro- duction by L. E. Sayre, ph.g., Professor of Pharmacy in, and Dean of, the Dept, of Pharmacy, University of Kansas. i2mo. Cloth, 2.00 Anderson, (McCall) Skin Diseases. A complete Text-book, with Colored Plates and numerous Wood Engravings. 8vo. Cloth, 4.50; Leather, 5.50 Van Harlingen on Skin Diseases. A Handbook of the Dis- eases of the Skin, their Diagnosis and Treatment (arranged alpha- betically). By Arthur Van Harlingen, m.d., Clinical Lecturer on Dermatology, Jefferson Medical College; Prof, of Diseases of the Skin in the Philadelphia Polyclinic. 2d Edition. Enlarged. With colored and other plates and illustrations. i2mo. Cloth, 2.50 See pages 2 to 5 for list of New Manuals. SKIN DISEASES. STUDENTS’ TEXT-BOOKS AND MANUALS. 13 SURGERY AND BANDAGING. Moullin’s Surgery. 500 Illustrations (some colored), 200 of which are original. Cloth, net 7.00; Leather, net 8.00 Jacobson. Operations in Surgery. A Systematic Handbook for Physicians. Students, and Hospital Surgeons. By W. H. A. Jacobson, 8.a. Oxon., f.r.c.s. Eng.; Ass’t Surgeon Guy s Hos- pital; Surgeon at Royal Hospital for Children and Women, etc. 199 Illustrations. 1006 pages. 8vo. Cloth. 5.00; Leather, 6.00 Heath’s Minor Surgery, and Bandaging. Ninth Edition. 142 Illustrations. 60 Formulae and Diet Lists. Cloth, 2.00 Horwitz’s Compend of Surgery, Minor Surgery and Bandaging, Amputations, Fractures, Dislocations, Surgical Diseases, and the Latest Antiseptic Rules, etc., with Differential Diagnosis and Treatment. By Orville Horwitz, b.s., m.d., Demonstrator of Surgery, Jefferson Medical College. 4th edition. Enlarged and Rearranged. 136 Illustrations and 84 Formulae. i2mo. Cloth, 1.00; Interleaved for the addition of Notes, 1.25 * * The new Section on Bandaging and Surgical Dressings con- sists of 32 Pages and 41 Illustrations. Every Bandage of any importance is figured. This, with the Section on Ligation of Arteries, forms an ample Text-book for the Surgical Laboratory. Walsham. Manual of Practical Surgery. Third Edition. BtWm. J. Walsham, m.d., f.r.c.s., Asst. Surg. to, and Dem. of Practical Surg. in, St. Bartholomew’s Hospital; Surgeon to Metropolitan Free Hospital, London. With 318 Engravings. See page 2. Cloth, 3.00; Leather, 3.50 Holland. The Urine, and Common Poisons and The Milk. Chemical and Microscopical, for Laboratory Use. Illus- trated. Fourth Edition, ramo. Interleaved. Cloth, 1.00 Ralfe. Kidney Diseases and Urinary Derangements. 42 Illus- trations. i2mo. 572 pages. Cloth, 2.75 Marshall and Smith. OntheUrine. The Chemical Analysis of the Urine. By John Marshall, m.d., Chemical Laboratory Umv. of Penna; and Prof. E. F. Smith, ph.d. Col. Plates. Cloth, i.oo Memminger. Diagnosis by the Urine. Illustrated. Cloth, 1.00 Tyson On the Urine. A Practical Guide to the Examination of Urine. With Colored Plates and Wood Engravings. 7th Ed. Enlarged, umo. Cloth, 1.50 Van Nuys, Urine Analysis. Illus. Cloth, 2.00 URINE, URINARY ORGANS, ETC. Hill and Cooper. Student’s Manual of Venereal Diseases, with Formulae. Fourth Edition. i2mo. Cloth, i.oo VENEREAL DISEASES. See pages 14 and is for list of ? Quiz- Compends f PQUIZ-COMPENDS? The Best Compends for Students’ Use in the Quiz Class, and when Pre- paring for Examinations. Compiled in accordance with the latest teachings of promi- nent Lecturers and the most popular Text-books. They form a most complete, practical, and exhaustive set of manuals, containing information nowhere else col- lected in such a condensed, practical shape. Thoroughly up to the times in every respect, containing many new prescriptions and formulae, and over two hundred and fifty illustrations, many of which have been drawn and engraved specially for this series. The authors have had large experience as quiz-masters and attaches of colleges, with exceptional opportunities for noting the most recent advances and methods. Cloth, each $1.00. Interleaved for Notes, $1.25. No. 1. HUMAN ANATOMY, “ Based upon Gray." Fifth Enlarged Edition, including Visceral Anatomy, formerly published separately. 16 Lithograph Plates, New Tables, and 117 other Illustrations. By Samuel O. L. Pottek, m.a., m.d., m r.c.p. (Lond.), late A. A. Surgeon U. S. Army, Professor of Practice, Cooper Medical College, San Fran- cisco. Nos. 2 and 3. PRACTICE OF MEDICINE. Fourth Edi- tion. By Daniel E. Hughes, m.d., Demonstrator of Clinical Medicine in Jefferson Medical College, Philadelphia. In two parts. Part I.—Continued, Eruptive, and Periodical Fevers, Diseases of the Stomach, Intestines, Peritoneum, Biliary Passages, Liver, Kidneys, etc. (including Tests for Urine), General Diseases, etc. Part II.—Diseases of the Respiratory System (including Phy- sical Diagnosis), Circulatory System, and Nervous System; Dis- eases of the Blood, etc. *** These little books can be regarded as a full set of notes upon the Practice of Medicine, containing the Synonyms, Definitions, Causes, Symptoms, Prognosis, Diagnosis, Treatment, etc., of each disease, and including a number of prescriptions hitherto unpub- lished. No. 4. PHYSIOLOGY, including Embryology. Sixth Edition. By Albert P. Brubaker, m.d., Prof, of Physiology, Penn’a College of Dental Surgery; Demonstrator of Physiology in Jefferson Medical College, Philadelphia. Revised, Enlarged, with new Illustrations. No. 5. OBSTETRICS. Illustrated. Fourth Edition. By Henry G. Landis, m.d.. Prof, of Obstetrics and Diseases of Women in Starling Medical College, Columbus, O. Revised Edition. New Illustrations. BLAKISTON’S ? QUIZ-COMPENDS ? No. 6. MATERIA MEDICA, THERAPEUTICS, AND PRESCRIPTION WRITING. Fifth Revised Edition. With especial Reference to the Physiological Action of Drugs, and a complete article on Prescription Writing. Based on the Last Revision of the U. S. Pharmacopoeia, and including many unofficinal remedies. By Samuel O. L. Potter, m.a., m.d., m.r.c.p. (Lond.), late A. A. Surg. U. S. Army ; Prof, of Practice, Cooper Medical College, San Francisco. Improved and Enlarged, with Index. No. 7. GYNASCOLOGY. A Compend of Diseases of Women. By Henry Morris, m.d., Demonstrator of Obstetrics, Jefferson Medical College, Philadelphia. 45 Illustrations. No. 8. DISEASES OF THE EYE AND REFRACTION, including Treatment and Surgery. By L. Webster Fox, m.d., Chief Clinical Assistant Ophthalmological Dept., Jefferson Med- ical College, etc., and Geo. M. Gould, m.d. 71 Illustrations, 39 Formula. Second Enlarged and Improved Edition. Index. No. 9. SURGERY, Minor Surgery and Bandaging. Illus- trated. Fourth Edition. Including Fractures, Wounds, Dislocations, Sprains, Amputations, and other operations; Inflam- mation, Suppuration, Ulcers, Syphilis, Tumors, Shock, etc. Diseases of the Spine, Ear, Bladder, Testicles, Anus, and other Surgical Diseases. By Orville Horwitz, a.m., m.d., Demonstrator of Surgery, Jefferson Medical College. Revised and Enlarged. 84 Formula and 136 Illustrations. No. 10. CHEMISTRY. Inorganic and Organic. For Medical and Dental Students. Including Urinary Analysis and Medical Chemistry. By Henry Leffmann, m.d., Prof, of Chemistry in Penn’a College of Dental Surgery, Phila. Third Edition, Revised and Rewritten, with Index. No. 11. PHARMACY. Based upon “ Remington’s Text-book of Pharmacy.” By F. E. Stewart, m.d., ph.g., Quiz-Master at Philadelphia College of Pharmacy. Third Edition, Revised. No. 12. VETERINARY ANATOMY AND PHYSIOL- OGY. 29 Illustrations. By Wm. R. Ballou, m.d., Prof, of Equine Anatomy at N. Y. College of Veterinary Surgeons. No. 13. DENTAL PATHOLOGY AND DENTAL MEDI- CINE. Containing all the most noteworthy points of interest to the Dental student. By Geo. W. Warren, d.d.s., Clinical Chief, Penn’a College of Dental Surgery, Philadelphia. Illus. No. 14. DISEASES OF CHILDREN. By Dr. Marcus P. Hatfield, Prof, of Diseases of Children, Chicago Medical College. Colored Plate. Bound in Cloth, $1. Interleaved, for the Addition of Notes, $1.25. These books are constantly revised to keep up with the latest teachings and discoveries, so that they contain all the new methods and principles. No series of books are so complete in detail, concise in language, or so well printed and bound. Each one forms a complete set of notes upon the subject under consideration. Illustrated Descriptive Circular Free. JUST PUBLISHED. GOULD’S NEW Medical Dictionary COMPACT. CONCISE. PRAGTIGAL. AGGURATE. COMPREHENSIVE UP TO DATE. It contains Tables of the Arteries, Bacilli, Gan- glia, Leucomaines, Micrococci, Muscles, Nerves, Plexuses, Ptomaines, etc., etc., that will be found of great use to the student. Small octavo, 520 pages, Half-Dark Leather, . #3.25 With Thumb Index, Half Morocco, marbled edges, 4.25 From J. M. DaCOSTA, M. D., Professor of Practice and Clinical Medicine, Jefferson Medical College, Philadelphia. " I find it an excellent work, doing credit to the learning and discrimination of the author." *** Sample Pages free.