ANATOMY SCIENTIFIC AND POPULAR BY GEORGE DUTTON, A.B., M.D. PRESIDENT OF THE AMERICAN HEALTH SOCIETY, FOUNDER AND DEAN OF THE VERMONT MEDICAL COLLEGE, AUTHOR OF “CONSUMPTION AND RHEUMATISM,” “MEDICAL NOTES” FOR STUDENTS, “HYGIENIC MANUAL,” “ONTOLOGY,” “ DUTTON’S SCHOOL CHARTS,” ETC. Secortb Cbition THOROUGHLY REVISED AND CORRECTED WITH AN APPENDIX CONTAINING A COMPLETE ALPHABETICAL LIST OF THE MUSCLES, BRIEFLY AND PLAINLY DESCRIBED FINELY ILLUSTRATED BOSTON, MASS.: CYNOSURE PUBLISHING COMPANY 1892 Copyright, 1892, by George Dutton, A.M., M.D. ALL RIGHTS RESERVED. Frank Wood, Printer• “Male and Female created He them.”—Gen. i. 27. PREFACE. This work is offered to the public, including families, mechanics, artisans, and the general student, as well as members of the medical profession and medical students; not with the desire to supplant other valuable works, but with the hope of extending among the whole people a better knowledge of the human body, which has been called the “ temple of the living God.” A correct medical education is the direct path toward physical perfection; and some knowledge of the structure of the physical body is the necessary basis of a correct medical education. As the common mind advances, the medical profession will necessarily ad- vance. Knowledge is the birthright of every human being; and no knowledge is more useful than that of the human organization, and the subtile and mysterious force (or mind) that governs it. “Know thyself,” said the Greek sage, “ descended from heaven to be en- graven upon the tablet of enduring memory.” What self is, no one has yet been able to tell us. Man is a being of such proportions (considered mentally) and complexity, that he completely baffles description, and we shall not attempt it here. Whether he is spirit or matter, either or both, as many philosophers claim and deny, we do not now affirm. That he has a body, and lives in a world of cause and effect, is evident. The body is constructed on strictly mechanical principles, and is well considered as an instrument for use in the material world, or as a tenement which man holds in his present mode of being. It is our 6 PREFACE. object in this volume to call attention to the structure of this tene- ment, or instrument, in such a manner that through a better and more general knowledge of its nature the readers may be enabled to enjoy the use of better instruments, and eventually fulfill the scriptural request to “present your bodies a living sacrifice, holy and acceptable unto God, which is your reasonable service.” One peculiar feature of the work is the explanation of all technical and difficult terms in plain English, which serves to make this hereto- fore difficult study accessible to all. The figure on the title-page is in the form of a spherical triangle, of which use is made in the higher department of mathematics. It bears the words, “Quae prosunt omnibus” (which are useful to all); and contains the wand of Mercury (the caduceus), to which ancient poets attributed wonderful powers. The rod represents power, the serpents (in the old Coptic language), wisdom, and the wings, aspi- ration, or diligence and activity. CONTENTS. Pagk General Introduction 17 General Anatomy , 22 Osteology (Bone Study) 23 Arthrology (Joint Study 120 Myology (Muscle Study) 144 Angiology (Vessel Study) 202 Neurology (Nerve Study) 268 Organs of Sense 333 Organs of Digestion . . . 358 Organs of Voice and Respiration 388 The Urinary Organs 400 Male Genital Organs . 409 Female Genital Organs 416 Fcetal Circulation 421 Surgical Anatomy 425 List of Illustrations. Frontispiece. INTRODUCTION. Fig. Page 1. The Human Embryo .......... 18 2. The Cell, or Ovum 18 3. The Corpuscles of the Blood 20 4. Blood Crystals ............ 21 OSTEOLOGY. 5. The Skeleton 24 6. The Spinal Column ........... 26 7. Side view of the Skull .......... 35 8. The Lower Jaw 40 9. Superior Maxillary Bone — outer surface ...... 41 10. Superior Maxillary Bone — inner surface ...... 42 11. Bones of the Face 43 12. Inferior Turbinated Bone — inner surface ...... 45 13. Inferior Turbinated Bone—outer surface ...... 45 14. The Vomer 46 15. Nasal Bone—inner surface ......... 46 16. Nasal Bone — outer surface 47 17. The Lachrymal Bone .......... 47 18. Malar Bone — outer surface ......... 48 19. Malar Bone — inner surface ......... 48 20. Palate Bone — posterior view ......... 49 21. Palate Bone — internal view ......... 50 22. Ethmoid Bone — upper and right sides ....... 50 23. Ethmoid Bone — vertical section ........ 51 24. Sphenoid Bone — anterior surface ........ 52 25. Sphenoid Bone — cerebral surface ........ 53 26. Temporal Bone — inner surface ........ 55 27. Temporal Bone — outer surface ........ 56 28. Frontal Bone—-outer surface ......... 60 29. Frontal Bone — inner surface ......... 61 30. Frontal Bone — at birth .......... 61 31. Skull — atbirth ............ 62 32. Parietal Bone — outer surface ......... 63 33. Parietal Bone — inner surface ......... 63 34. Occipital Bone — outer surface 64 10 LIST OF ILLUSTRATIONS. 35* Occipital Bone — inner surface ........ 66 36. Hvoid Bone 67 37. Inner Wall of the Nose .......... 68 38. Outer Wall of the Nasal Fossa ......... 69 39. Base of the Skull — under surface ........ 70 40. The Atlas 72 41. A Cervical Vertebra ........... 72 42. The Vertebra Prominens .......... 73 43. A Dorsal Vertebra ........... 74 44. A Lumbar Vertebra 75 45. The Sacrum 77 46. The Coccyx 77 47. A True Rib (costa) 78 48. The Sternum — reduced in size ........ 80 49. The Clavicle — anterior surface 81 50. The Clavicle — inferior surface ........ 81 51. The Scapula — anterior surface ........ 83 52. The Scapula — posterior surface ........ 85 53. The Humerus — posterior view ........ 87 54. The Humerus — anterior view ......... 87 55. Bones of the Forearm—anterior surface . ...... 89 56. Bones of the Forearm — postei'ior view ....... 91 57. Bones of the Left Hand—palmar surface ...... 94 58. Bones of the Left Hand — dorsal surface ....... 96 59. Arch of the Foot ........... 98 60. Bones of the Right Foot — upper surface ...... 99 61. Bones of the Right Foot—undersurface ...... 100 62. Bones of the Leg — anterior view ........ 104 63. Bones of the Leg — posterior view . . . . . . . . 104 64. The Knee-pan 106 65. The Thigh-bone — posterior surface ....... 107 66. The Thigh-bone — anterior surface ........ 107 67. Development of*the Thigh-bone ........ 109 68. Right Hip-bone — external surface . . 111 69. Right Hip-bone — internal surface ........ 113 70. Development of the Hip-bone . . . 117 71. Female Pelvis 118 72. Male Pelvis 118 73. Vertical Section of the Pelvis . 119 ARTHROLOGY. 74. Temporo-maxillary Articulation . . . . . . . . 124 75. Articulation of the Atlas and Axis ........ 125 76. Sterno-clavicular Articulation ......... 129 77. Sterno-clavicular Ligaments ......... 129 78. Left Shoulder Joint . . . ... . . . . . . 130 79. Left Elbow Joint 132 80. Head of the Radius, removed from the Orbicular Ligament . . . 132 81. Ligaments of the Wrist and Palm — posterior 134 82. Ligaments of the Wrist and Palm — anterior ...... 134 LIST OF ILLUSTRATIONS. 11 83. Synovial Membranes of the Wrist ........ 135 84. Ankle Joint — outer side . . . . . . . . ■ . 136 85. Interosseous Ligaments of the Cuneiform Bones 137 86. Ankle Joint—inner side .......... 137 87. Ligaments of the Sole of the Foot 138 88. Synovial Membranes of the Ankle 135 89. Knee-joint — posterior view ......... 140 90. Knee-joint — anterior view ......... 141 91. Head of Tibia and Semilunar Cartilages . ...... 141 92. Crucial Ligaments 93. Hip-joint, laid open MYOLOGY. 94. Muscles of the Head, Face, and Neck 147 95. Muscles of the Cranium and Face ........ 148 96. Muscles of the Pharynx — external view ....... 151 97. A Transverse Section of the Abdomen 132 98. The Diaphragm ........... 133 99. Muscles of the Thigh and Leg 136 100. Muscles of the Back of the Leg 157 101-2 Muscles of the Sole — first layer X38 103. Muscles of the Front of the Leg 135 104. Muscles of the Sole—second layer ........ 160 105. Muscles of the Sole — third layer ........ 161 106. Muscles of the Sole ........... 162 107. Under Surface of the Diaphragm X64 108. Muscles of the Back — first layer on the left ...... 166 109. Muscles of the Chest and Biceps of the Arm 168 no. External Oblique Muscle and Spermatic Cord ..... 169 in. The Internal Oblique and Cremaster Muscles ..... 170 112. Transverse and Rectus Muscles of the Abdomen 172 113. Muscles of the Neck—anterior view ....... 174 114. The Constrictor Muscles — seen from behind 173 115. The Temporal Muscle 177 116. The Pterygoid Muscles .......... 178 117. Muscles of the Back of the Leg — superficial layer . .... 179 118. Occipito-frontalis and External Muscles of the Ear .... 180 119. Muscles of the Neck and Boundaries of the Surgical Triangles . . 181 120. Muscles of the Back ........... 183 121. The Triceps and Muscles of the back part of the Scapula ... 184 122. Muscles of the Chest and front of the Arm ...... 185 123. Muscles of the Iliac and Anterior Femoral Regions .... 187 124. Muscles of the Hip and Thigh 188 125. Deep Muscles of the Femoral Region — inner side . .... 190 126. Muscles of the Orbit xqx 127. Fascia Lata and Saphenous Opening ....... 192 128. Muscles of the Left Hand — palmar surface ...... 194 129. Muscles of the Front of the Forearm ....... 193 130. Transverse Section through the Wrist 196 131. Front of the Left Forearm—deep muscles ...... 197 132. Palmar Interossei of the Left Hand 198 12 LIST OF ILLUSTRATIONS. 133. Muscles of the Back of the Forearm 199 134. Posterior Surface of the Forearm — deep muscles 200 135. Dorsal Interossei of the Left Hand 201 ANGIOLOGY. 136. Right Auricle and Ventricle of the Heart 203 137. Left Auricle and Ventricle of the Heart 205 138. Relative Position of the Valves of the Heart 206 139. Arch of the Aorta and its Branches 210 140. The Coeliac Axis and its Branches 213 141. The Cceliac Axis in connection with the Stomach ..... 214. 142. Superior Mesenteric Artery and its Branches 215 143. Anastomosis of the Mesenteric Arteries 216 144. Inferior Mesenteric Artery a*nd its Branches 217 145. Internal View of the Femoral and Internal Abdominal Rings . . 221 146. Scarpa’s Triangle 222 147. The Femoral Artery 223 148. The Popliteal, Posterior Tibial, and Peroneal Arteries .... 225 149. The Plantar Arteries — deep view ........ 226 150-1 The Subclavian Artery; its Portions, Branches, etc 228 152. Arteries at the base of the Brain 230 153. The Axillary Artery and its Branches 232 154. The Brachial Artery ........... 233 155. Ulnar and Radial Arteries — deep view 234 156. Brachial Artery, Branches, and Inosculations 235 157. Radial and Ulnar Arteries . . . . * 236 158. Superficial and Deep Palmar Arches . 237 159. External Carotid Artery and its Branches 239 160. Arteries of the Face and Scalp ......... 240 161. Branches of the External Carotid Artery ...... 241 162. External and Common Carotid Arteries 242 163. Arteries of the Neck ........... 244 164. Portal Vein and its Branches 248 165. Sinuses at the Base of the Skull 249 166. Superior Vena Cava and its Tributaries 249 167. Vena Azygos — Major and Minor ........ 251 168. Veins of the Elbow ........... 252 169. Vertical Section of the Skull, showing the Sinuses .... 254 170. Veins of the Head and Neck . 253 171. Veins of the Diploe ........... 257 172-3 Long and Short Saphenous Veins 259 174-6 Spinal Veins ............ 260-1 177• Lymphatic Vessels and Glands of the Head, Face, and Neck . . . 262 178. Deep Lymphatics and Glands of the Neck and Chest .... 263 179. Thoracic and Right Lymphatic Ducts ....... 264 180. Superficial Lymphatics and Glands of the Lower Extremity . . . 265 181. Inguinal Region, showing the Saphenous Opening, Cribriform Fascia, Superficial Vessels, and Glands 266 LIST OF ILLUSTRATIONS. 13 NEUROLOGY. 182. Cerebro-spinal System of Nerves 269 183. Base of the Brain 270 184. Diagram to show the Formation of a Sinus ...... 272 185. Section of the Spinal Cord ......... 273 186. Ligamentum Denticulatum ......... 273 187. The Spinal Cord and its Membranes ....... 274 188. Section of the Spinal Cord ......... 274 189. Spinal Cord : its Fissures and Columns ....... 275 190. Course of the Fibers through the Medulla Oblongata .... 276 191-3 Different Views of the Medulla ........ 278 194. Section ot the Bmin ........... 280 195. Corpora Quadrigemina, etc. ......... 280 196. Vertical Section of the Cerebellum . 281 197. Third and Fourth Ventricles ......... 282 198. Under Surface of the Brain ......... 283 199. Convolutions of the Brain ......... 284 200. The Lateral Ventricles . . . . . . . . . . 285 201. Under Surface of the Anterior Lobe of the Cerebral Hemisphere . . 286 202. Course of Fibers through the Medulla and Pons ..... 287 203. Convolutions of the Inner Surface of the Cerebral Hemisphere . . 288 204. Convolutions of the Upper Surface of the Brain ..... 289 205. Transverse Vertical Section of the Brain ...... 290 206. Section of the Brain ........... 291 207. Section of the Corpus Callosum ........ 292 208. Diagram of the Fornix .......... 293 209. Lateral Ventricles and Velum Interpositum ...... 294 210. Reflex Action ............ 296 2x1. First Six Cranial Nerves .......... 298 212. Last Six Ci'anial Nerves .......... 299 213. Olfactory and Anterior Palatine Nerves ....... 301 214. Otic Ganglion ............ 302 215. Nerves of the Orbit . 304 216. Fifth Cranial Nerve ........... 305 217. Spheno-palatine Ganglion ......... 306 218. Inferior Maxillary Nerve .......... 307 219. Branches of the Facial Nerve ......... 308 220. Facial Nerve in the Temporal Bone . ....... 309 221. Anterior and Posterior Roots of a Spinal Nerve ..... 313 222-3 Spinal Nerves 314-15 224. Brachial Plexus ............ 317 225. Nerves of the Upper Extremity 318 226. Suprascapular, Circumflex, and Musculo-spiral Nerves .... 319 227-8 Views of Cutaneous Nerves of the Upper Extremity . . . . 321 229-30 Nerves of the Lower Extremity ........ 323 231. Cutaneous Nerves of the Lower Extremity ...... 325 232. The Plantar Nerves ........... 326 233. Nerve-cells ............ 327 234. Sympathetic Ganglia and Nerves 328 235. Diagram of the Sympathetic System 331 14 LIST OF ILLUSTRATIONS. ORGANS OF SENSE, 236. The Integument, or Skin 334. 237-9 Upper Surface and Papillae of the Tongue 338 240. Muscles and Nerves of the Tongue ........ 339 241. Muscles of the Tongue .......... 340 242-3 Bones and Cartilages of the Nose ........ 342 244. Pharynx, Larynx, Mouth, and Nasal Fossae ...... 342 245. The Eyeball and Optic Nerve 344 246. Section of the Eyeball 344 247. Coats of the Eyeball and Retina ........ 345 248. The Retina ............ 346 249. Layers of the Retina 346 250. The Crystalline Lens .......... 347 251. Insertion of the Recti Muscles ......... 348 252-3 Views of the Lachrymal Apparatus 349 254. The Lachrymal and Meibomian Glands ....... 350 255. The External Ear 351 256. The Ossicles of the Ear .......... 352 257. The Labyrinth 353 258. The Auditory Nerve . . . . . . . . . . . 354 259. The Cochlea 355 ORGANS OF DIGESTION. 260. The Temporary Teeth 360 261. Section of a Bicuspid Tooth ......... 361 262. Section of a Molar Tooth .......... 361 263. The Permanent Teeth .......... 362 264. The Salivary Glands ........... 364 265. Forms of Glands 366 266. Regions of the Abdomen . . . . . . . . . . 368 267. Diagram of the Peritoneum ......... 370 268. Muscular Coat of the Stomach ........ 372 269. Mucous Coat of the Stomach 374 270. The Ileo-caecal Valve . 377 271. Commencement of the Colon ......... 378 272. Under Surface of the Liver ......... 381 273. Upper Surface of the Liver 382 274. Under Surface of the Liver ......... 384 275. The Pancreas 385 ORGANS OF VOICE AND RESPIRATION. 276. Section of the Thorax 388 277. Heart and Lungs . 390 278. Larynx, Trachea, and Bronchi 393 279. Side of the Larynx 394 280. Side of the Muscles of the Larynx 395 281. Cartilages of the Larynx 396 282. Interior of the Larynx 397 LIST OF ILLUSTRATIONS. 15 283* The Glottis Dilated 398 284. The Glottis at Rest 398 285. Glottis Closed 399 THE URINARY ORGANS. 286. Kidneys, Ureters, and Bladder 401 287-8 Sections of the Kidney 402 289-90 Structure of the Kidney 403 291. The Bladder and Urethra .......... 404 292. Bladder and Urethra (another view) 405 293. Vertical Section of the Bladder, Penis, and Urethra .... 407 MALE GENITAL ORGANS. 294. The Testis in Situ 410 295. Vertical Section of the Testis 412 296. Ureters and Seminal Vesicles . 413 FEMALE GENITAL ORGANS. 297. Uterus and its Appendages 417 298. Female Pelvis and Viscera 418 299. Section of the Ovary 419 FOETAL CIRCULATION. 300. Foetal Circulation ........... 422 301. Foetal Circulation (another view) ........ 423 SURGICAL ANATOMY. 302. Inguinal Canal and Spermatic Cord 426 303. The Axillary Space 431 General Introduction. THE cell is the material starting-point of every human organism ; and, in some form, makes up the structure of all organic bodies, both animal and vegetable. The typical organic cell consists from without inward of cell mem- brane, protoplasmic contents, nucleus, and nucleolus. Whether the cell- membrane is anything more than the wall, or outer surface of the proto- plasm, is open to further investigation. The composition of the protoplasm (the fluidic contents of the cell) varies with the age of the cell. At first it consists of a homogeneous albuminoid (resembling albumen, like the white of an egg) ; but later there appear granulations, coloring, or fatty matter, and the whole may become hardened into horn, or bone. The nucleus (kernel) examined with the microscope presents the appearance of a sphere, the contents of which are more or less liquid and transparent. The nucleus is surrounded by a capsule, so thin and transparent that its presence is demonstrated chiefly by the current observable in its contents. In the interior of the nucleus of the most perfect cell is discernible with the microscope a brilliant central point, or globule, called the nucle- olus (little nucleus). In some cells there are two or three brilliant points, or nucleoli (plural of nucleolus). The nucleolus is of later formation, and results from the differenti- ation (development of variety) in the liquid mass of the nucleus. Some cells go through their whole period of existence without ever possessing a nucleolus. The nucleus and nucleolus are endowed with increased vital power, and are able to resist the action of acids and alka- lies that destroy the body of the cell. Bioplasm (life-formed) is another and perhaps better name for that which is called protoplasm (first-formed). Every organic parent cell is endowed with vital properties, motion, nutrition, reproduction, etc., but the most remarkable property of cells is that of differentiation; so that out of cells which are to all appearance identical, are developed all the different tissues and fluids of the body; 18 GENERAL INTRODUCTION. and in the growth and development of the body, from the parent cell to the perfected organism, there is constantly increasing evidence of that wondrous power known to man as Life. In the earlier stages of de- velopment it is impossible to distinguish the worm from the philosopher. We give below the figure of the human embryo of seven week’s develop- ment. Fig. i. Cells are multiplied by a process known as segmentation (splitting, or dividing), or by gemmation (budding). In the former process the Fig. 2. THE CELL, OR OVUM, IN SUCCESSIVE STAGES OF DEVELOPMENT (MAGNIFIED). nucleus splits, and forms two ; in the latter, the cell sends off a process, or bud, and thus new nuclei (plural of nucleus) are produced, which be- come detached from the parent cell, and surrounded by their own cell substance. The continuous development of cells in the formation of tissues, was called by Virchow “proliferation (bearing of offspring) of cells.” The nucleus is sometimes called the cytoblast (cell-germ). By Professor Agassiz the cell-wall was termed “ectoblast” (outer GENERAL INTRODUCTION. 19 germ); the nucleus was the “mesoblast” (middle germ); and the nucleolus was the “entoblast” (inner germ). Lymph and chyle corpuscles (little bodies) were termed by Henle “leucocytes” (white cells); and when the white cells of the blood pre- dominate, or there is a deficiency of coloring matter, or a deficiency of red corpuscles in the blood, the condition is termed “lucaemia” (white blood), or leucocythemia (white-cell blood). FLUIDS. The fluids of the body are the chyle ("juice”), which is absorbed by the mucous membrane of the small intestine ; the lymph (a clear fluid, like water), which is conveyed by the lymphatic vessels ; the blood, which is conveyed by the arteries, capillaries, and veins ; and the various secretions. The secretions will be mentioned further, in connection with the various organs and membranes that secrete them. The fluids are about nine times the amount of solids. The semi-solids, or soft parts, make up the rest of the body. CHYLE. The chyle is a milk-white fluid that in some respects resembles the blood. Like the blood, it coagulates on standing, and, like the blood, contains white corpuscles (little bodies). It is at first merely an emul- sion, formed by the action of the pancreatic juice and bile upon the fatty matters of the food taken ; but after passing through the mesenteric glands, the chyle contains chyle corpuscles. These corpuscles are iden- tical with the white corpuscles of the blood. Lymph.—The lymph is the liquid portion of the blood transuded from the capillaries during the process of nutrition, and returned again to the circulation through the lymphatic vessels. It resembles the plasma, or the serum, according as it contains more or less fibrin. THE BLOOD. (Latin — '■‘■Sanguis."') The blood is an animal fluid, and is pre-eminently vital. Its amount in the body, according to Harvey, who is credited with the discovery of its circulation, is about eight pounds. Haller estimated it as high as thirty pounds. More recent authors fix it at about one thirteenth of the weight of the body. (It is certain that Michael Servetus, a Spanish physician who suffered martyrdom in the time of Calvin, understood the circulation through the lungs before the time of Harvey, but the latter demonstrated the systemic circulation.) 20 GENERAL INTRODUCTION. The blood undergoes great changes in the lungs ; but the most evident is a change in color from dark red, or purple, to a bright red, or scarlet. This change is due to the oxidation (absorption of oxygen) and decarbonization (removal of carbon) of the blood in the lungs. Examined with the microscope the blood appears to be full of cells, more or less flattened, which have received the name of blood corpuscles (little bodies), blood discs (plates), or blood globules (little globes). Fig. 3- BLOOD CORPUSCLES AS THEY APPEAR UNDER THE MICROSCOPE. These bodies, or cells, are of two kinds, and are distinguished by their color, as the white and the red corpuscles. The white are properly lymph corpuscles, which are as yet immature, and freshly received into the blood. The specific gravity of the blood is about 1,055, water being 1,000. Arterial blood is somewhat lighter than venous blood, the difference being chiefly in the relative weight and change of quantity of the oxygen and carbon which each contains. Tested chemically, the blood is slightly alkaline. It is a composite fluid, and is the common carrier of waste and supply in the entire body, or at least in all parts supplied with blood-vessels (arteries and veins). Drawn from the living vessels, and allowed to stand, blood soon (ordinarily in five minutes) separates into two parts — a fluid called “serum,” and a “clot” (coagulum, or crassamentum). The clot consists of the blood corpuscles, inclosed in a substance known as “ fibrin ” (from fiber) which is held in solution in the blood, and is sometimes called by physicians “ coagulable lymph ” (a clear fluid capable of clotting.) The liquid portion of the blood, as it circulates in the vessels of the body, is called the “plasma” (something “formed,”) or “liquor sanguinis” (fluid of the blood.) The plasma holds fibrin in solution; the serum does not. Neither plasma nor serum contains properly any blood corpuscles. The latter composes about one GENERAL INTRODUCTION. 21 third the volume of the blood, and the plasma, two thirds. The fibrin of the blood varies from one to four per cent. The red globules are far more numerous than the white, but vary considerably in proportion. One white corpuscle to three or four hun- dred of the red, is the ordinary proportion. These little bodies (cor- puscles) are so small that it takes from 2,000 to 3,000 placed side by side to measure an inch. (See Fig. 3.) The serum of the blood is of a yellowish color, and contains so much albumen (a substance like the white of an egg) that it solidifies almost completely on being heated. The coloring matter of the blood is termed “ haematin ” (blood matter). Treated by certain chemical re-agents, three kinds of micro- Fig. 4. BLOOD CRYSTALS. scopic crystals, more or less resembling each other, can be obtained from haematin. The philosophy of coagulation of the blood is not well understood. Under normal circumstances the blood does not clot in the living blood- vessels, and is generally supposed not to clot in the living body; but considering coagulation as nearly synonymous with the formation of fibrin, it seems to be logically conclusive that it does take place within the body, probably after transudation from the capillaries (microscopic tubes that lie at the termination of the arteries); for the fibrin so formed is an essential element of the tissues of the body. It constitutes the threads from which the tissues are woven. General Anatomy. ANATOMY is the science of structure. The word is derived from the Greek, and signifies to “cut tip," or dissect; as it was by dissecting animal bodies that their structure first became known. But the facts of anatomy having been accurately observed and recorded, and the form and appearance of the various parts of the body having been modeled and illustrated by art, it is not essential that every student of this branch of natural science should take the same slow, tedious, and often unpleasant steps that led to its dis- covery and elucidation. By aid of the skeleton, charts, books, and illustrations, a very thorough knowledge of anatomy may be obtained ; but practical skill in surgery (“hand-work,” or manual operations) must be, in part, obtained by dissections. So long as the knife is to be used in surgery, there is nothing can take the place of experience. Human Anatomy is the study of human structures, including male and female. Comparative Anatomy compares the structure of lower animals with that of man. Surgical Anatomy is the more careful study of certain parts, or regions, of the body, on account of their surgical importance. Pathological, or Morbid Anatomy, is the study of structures altered by disease; as of cancers, tumors, etc. General Anatomy, descriptive anatomy, and morphology (study of form), are synonymous terms, and include, not only the form, but also the name, size, and situation of the various structures and organs, but are not supposed to include surgical anatomy, which is special. Histology (tissue-study) is sometimes considered synonymous with general anatomy,— the study of all the tissues,— but more commonly as synonymous with microscopic anatomy — the study of structures and tissues by aid of the microscope. OSTEOLOGY. 23 These terms are all used with reference to the study of the body while in a state of rest; while physiology (study of nature) studies the same in motion, as in life and health. The body is composed of hard and soft parts, and contains within it fluids of different kinds. The study of the hard parts is sometimes called Skeletology (study of the skeleton), and the study of the soft parts, Sarcology (study of flesh). Skeletology includes not only the study of the bones (Osteology), but also the study of the joints (Arthrology) and ligaments (S-yndes- mology); since the joints and ligaments form a part of the natural skel- eton ; and Sarcology includes Myology (study of the muscles), Neu- rology (study of the nerves), Angiology (study of vessels), Adenology (study of glands), Splanchnology (study of the viscera), and Derma- tology (study of the skin) The natural skeleton (dried-up body) is not convenient for the study of the bones which are concealed by the ligaments and parts dried down upon them ; and for this reason an artificial skeleton (the natural bones held together by art) is used. The bones of the body weigh on an average about ten pounds. Calcined, the body is reduced to half a pound. OSTEOLOGY (Study of the Bones). The bony system is the framework of the body, and, considered separately, is called the skeleton. The skeleton contains two hundred or more bones; but the number varies somewhat in different individ- uals and at different periods of life. At birth many of the bones are cartilaginous, while others are composed of two or more pieces, con- nected by cartilage, or membrane ; and in old age some of the bones become consolidated, especially the bones of the head. The bones give form and support to the body, serve to protect important organs, and are the levers, or passive organs of locomotion. The teeth differ in structure from the bones, and are, therefore, described separately. The bones that form the vault of the skull, usually eight in number, sometimes contain one or more extra pieces, which have been called Wormian bones, in honor of Wormius, although Andernach, of Strasburg, previously mentioned them. The knee-pans (patellae) are developed in the tendons of the mus- cles that extend the leg, and being in the form of a grain of sesamum, are sometimes called “sesamoid” bones. Other sesamoid bones are generally found developed in some of the tendons of the hands and feet, but, not being constant, are not enumerated among the bones of 24 OSTEOLOGY. F>g- 5- THE SKELETON. OSTEOLOGY. 25 the skeleton. The bones of the middle ear, six in number, three in each ear, in the adult, are sometimes included and sometimes omitted in the enumeration of the bones of the skeleton. If we omit the teeth, the Wormian bones, and the sesamoid in general, but include the knee- pans and the bones of the ear, we shall have in the adult 206 bones, which may be classified as follows, viz.: — Bones of the head . 28 tl “ trunk .... 54 ti “ upper extremities . . . 64 it “ lower “ . . 60 Total . . 206 the skeleton. The bones of the middle ear, six in number, three in each ear, in the adult, are sometimes included and sometimes omitted in the enumeration of the bones of the skeleton. If we omit the teeth, the Wormian bones, and the sesamoid in general, but include the knee- pans and the bones of the ear, we shall have in the adult 206 bones, which may be classified as follows, viz.: — Fig. 6. THE SPINAL COLUMN, OR “BACKBONE.” (LATERAL VIEW.) 27 OSTEOLOGY. the Macedonians. There are in each hand and foot three rows (pha- langes) of bones, but the thumbs and great toes do not extend into the third row (phalanx), having only 2 bones each. The 54 bones of the trunk form the spinal column, the thorax (sig- nifying “ a cuirass,” or coat of mail), and the pelvis (basin). The thorax, or chest, lodges and protects the chief organs of respiration and circulation. The spinal column, improperly called the backbone, is made up of 24 bones, called vertebrae (plural of vertebra), and 2 other bones, the sacrum and coccyx. The word vertebra signifies to turn ; and the first vertebra really turns upon the second when we turn the head. The vertebrae are divided into three regions — the cervical (neck), dorsal (back), and lumbar (loin) vertebrae. There are 7 cer- vical, 12 dorsal, and 5 lumbar vertebrae. The ribs (“costae,” plural of costa) extend from the bodies of the vertebrae around the sides of the chest (thorax), and inclose the heart and lungs. Of the 206 bones, 172 are in pairs, leaving only 34 single bones. The single bones are all in the median line of the body, and for this reason are sometimes called mesial (middle) bones. The mesial bones are the frontal, occip- ital, sphenoid, ethmoid, vomer, inferior maxillary, hyoid, sternum, the 24 vertebrae, sacrum, and coccyx. These all extend as far on one side of the median line as the other, and give attachment to pairs of mus- cles. Of the 86 pairs, there are 30 pairs each in the upper and lower extremities, 12 pairs of ribs, 6 pairs of bones in the face, 3 pairs in the ears, 2 pairs in the skull, 2 pairs in the shoulders, and 1 pair of hip bones. The 206 bones of the skeleton are all designated by the aid of fifty names. They are as follows : — Phalanges (bones of the fingers and toes) ... 56 bones Vertebrae (bones of the spinal column) .... 24 “ Ribs (called in Latin costce) . . . . . . 24 “ Metatarsal (in the instep) . . . . . . 10 “ Metacarpal (in the palm of the hand) .... 10 “ Cuneiform (wedge form) . . . . . . 8 “ Scaphoid (skiff-like) . . . . . . . 4 “ Parietal (“wall” of the skull) ..... 2 “ Temporal (“ time,” from Latin temfius) ... 2 *• Superior Maxillary (upper jaw) ..... 2 “ Malar (“ apple,” or cheek-bone) . . . . . 2 “ Nasal (nose) ......... 2 “ Lachrymal (tear) . . . . . . . . 2 “ Palate (roof of the mouth) . . . . . . 2 “ Inferior Turbinated (lower spongy bone of the nose) . 2 “ Malleus (“ hammer,” small bone of the ear) . . 2 “ Incus (“ anvil,” small bone of the ear) .... 2 “ Stapes (“ stirrup,” small bone of the ear) ... 2 “ 28 OSTEOLOGY. Clavicle (“ little key,” or collar-bone) .... 2 bones. Scapula (shoulder-blade) 2 “ Humerus (arm) 2 “ Ulna (one of the bones of the fore-arm) ... 2 “ Radius (one of the bones of the fore-arm) ... 2 “ Semilunar (“ half-moon,” in the wrist) ... 2 “ Pisiform (“ pea-form,” in the wrist) .... 2 “ Trapezium (in the wrist) ...... 2 “ Trapezoid (“ like a trapezium,” in the wrist) . . 2 “ Os magnum (“ great bone ” of the wrist) ... 2 “ Unciform (“ hook-form,” in the wrist) .... 2 “ Innominate (“ nameless,” hip-bone) .... 2“ Femur (thigh) ........ 2 “ Patella (knee-pan) . . . . . . . . 2 “ Tibia (one of the bones of the leg) .... 2 “ Fibula (one of the bones of the leg) .... 2 “ Os calcis (“heel-bone”) ....... 2 “ Astragalus (Gx-eek, a “ die,” in the ankle) ... 2 “ Cuboid (like a cube, in the ankle) ..... 2 “ Frontal (of the skull) . . . . . . . 1 “ Occipital (back pai't of the skull) 1 “ Sphenoid (“ wedge-like,” at the base of the bi-ain) . 1 “ Ethmoid (“ sieve-like,” between the eyeballs) . . 1 Vomer (“ plow share,” helps to divide the nasal cavities) 1 “ Infei-ior maxillary (lower jaw) ..... 1 “ Hyoid (at the base of the tongue) ..... 1 “ Sacrum (“ sacred,” back part of the pelvis) ... 1 “ Coccyx (“ cuckoo,” at the apex of the sacrum) . 1 “ Stei-num (“ solid,” the breast-bone) . , . . 1 “ Atlas (“ sustainer,” first vertebra) . .... 1 “ Axis (“ axle,” around which the atlas turns) . . 1 “ Vertebi'a prominens (prominent vertebi'a, the seventh) 1 “ (The last three ai-e numbered twice, being reckoned as vertebra;.) The three bones of the ear (“ ossicles,” or little bones) lie within the cavity called the tympanum (drum), which is hollowed out in the petrous (“rocky,” or hard) portion of the temporal bone on either side of the head at the base of the upper, or front brain. They are the malleus (hammer), incus (anvil), and stapes (stirrup), on each side. Besides the ear-bones, which are within the bones of the cranium, but do not form a part of its walls, the cranium has 8 bones. They are the frontal, occipital, sphenoid, ethmoid, two temporal, and two parietal. The 8 cuneiform bones are found in the ankles and wrists — 3 in each ankle and 1 in each wrist. The 4 scaphoid bones are also found in the ankles and wrists—1 in each wrist and ankle. Besides the scaphoid and 3 cuneiform, each ankle has 3 other bones — the astragalus, cuboid, and os calcis (heel-bone). The latter is sometimes called the calcaneum. OSTEOLOGY. 29 Besides the scaphoid and cuneiform, each wrist has 6 other bones — the semi-lunar, pisiform, trapezium, trapezoid, os magnum, and unciform. Four bones enter into the formation of the pelvis. They are the 2 hip-bones, the sacrum, and the coccyx. The shoulder has 2 bones, the scapula and clavicle. The arm has only 1 bone, the humerus. The fore-arm has 2 bones, the ulna and radius. The hand has 27 bones—.8 in the wrist, 5 in the palm (metacarpal), and 14 in the thumb and fingers. The cuneiform bones of the ankle are designated as internal, middle, and external cuneiform ; or, first, second, and third cuneiform. Two sesamoid bones are generally found at the base of each thumb and great toe. The sesamoid bones are developed in the tendons of muscles. We give below a tabular view of the bones. The bones of the head include the bones of the cranium and face. Bones of the Cranium. 1 Frontal, 1 Occipital, 1 Sphenoid, 1 Ethmoid, 2 Temporal, 2 Parietal, Forming the walls of the cranium. 6 Small ear-bones, 3 in each ear. Total, 14 Bones of the Face. i Vomer, 1 Inferior maxillary, 2 Superior maxillary, 2 malar, 2 lachrymal, 2 palate, 2 nasal, 2 inferior turbinated. Total, 14 Bones of the Trunk. 24 Vertebrae, 24 Ribs, 2 Hip (ossa innominata), 1 Sternum, 1 Hyoid, i Sacrum, 1 Coccyx. Total, 54 OSTEOLOGY. Bones of the Upper Extremity* Scapula, Clavicle. Shoulder, Arm — Humerus. Forearm, Ulna, Radius. Scaphoid, Semi-lunar, Cuneiform, Pisiform, Trapezium, Trapezoid, Os magnum, Unciform. Wrist, Palm—First, second, third, fourth, and fifth metacarpal bone. Thumb and Fingers—Three phalanges, containing 14 bones. Total, 32 (on each side). Bones of the Lower Extremity. Thigh — Femur. Leg, Tibia, Fibula, Knee-pan (patella), Astragalus, Scaphoid, Cuboid, Os calcis, Three Cuneiform. Ankle, Instep — First, second, third, fourth, fifth metatarsal bone. Toes — Three Phalanges, containing 14 bones. Total, 30 (in each lower extremity). The bones are composed of animal and mineral matter in the pro- portion of one to two, differing somewhat in different parts of the body, in different individuals, and at different periods of life. The animal matter is mostly gelatine, and gives toughness and elasticity. The mineral matter, called also earthy, and inorganic matter, is chiefly phosphate and carbonate of lime. It gives hardness and solidity. In old age the earthy matter predominates ; in youth, the animal matter. In rachitis (rickets) the mineral matter is usually deficient, and the bones lack firmness. Blood-vessels and nerves enter the bones, like other parts of the body. The arteries that supply the medullary canal of the long bones are called nutrient arteries. The bones, except their cartilaginous extremities, are covered by a tough, fibrous membrane, called the periosteum (around the bone), which serves as a nidus (nest) for the ramification (branching) of ves- sels before entering the bone. OSTEOLOGY. 31 Bone is developed, for the most part, in temporary cartilage; but in the vault of the cranium and some other parts, in temporary mem- brane ; and ossification commences by the deposition of mineral matter in the temporary membrane, or cartilage. The point where the min- eral matter is first deposited is called the “ punctum ossificationis ” (point of ossification), or center of ossification. Some bones are devel- oped from a single center, others from several centers. The sacrum has about thirty-five centers of ossification. The long bones have usu- ally three or more centers: one for the shaft, and one fcr more for each end. The humerus is developed from seven centers; the ulna and radius, tibia and fibula, from three each. The femur has five centers of ossification; the patella usually one, but sometimes two. The frontal bone is developed from two centers, and at birth consists of two pieces, which usually unite in the median line. Each parietal bone is usually developed from a single center ; while the occipital bone has four centers of ossification. The sternum, including the ensiform appendix, has six centers: one for the manubrium, four for the gladi- olus, and one for the ensiform appendix. The gladiolus becomes en- tirely ossified at middle life, but it rarely unites with the manubrium till a much later period. In respect to shape the bones form four classes : the long, short, flat, and irregular. The long bones and the short together, include all the bones of the upper and lower extremities and the two clavicles. Each long bone consists of a cylinder, or shaft, and two extremities. The short bones are the bones of the wrist and ankle. The ribs are flat and long, but are classed with the flat. The innominate are flat, and very irregular; they are also classed with the flat. The other flat bones are the occipital, frontal, parietal, nasal, lachrymal, vomer, scapula, sternum, and patella. The irregular bones are the vertebrae, sacrum, and coccyx, the temporal, sphenoid, ethmoid, superior maxillary, malar, palate, inferior turbinated, inferior maxillary, malleus, incus, stapes, and hyoid ; mak- ing 46 of the irregular, 40 flat, 30 short, and 90 long. The long bones serve as pillars of support, and as levers for the muscles. The flat bones serve to protect important organs beneath or within, as the bones of the cranium, thorax, and pelvis. Of the 206 bones of the adult, 188 have muscles attached to them for support or motion. The following have no muscles attached: — 1 Ethmoid, 1 Vomer, 2 Nasal bones, 32 OSTEOLOGY. 2 Inci (plural of incus), 2 Inferior turbinated, 2 Astragali (plural of astragalus), 2 Semi-lunar, 2 Scaphoid (of the wrist), 2 Cuneiform of the wrist, and 2 Middle cuneiform of the ankle. Total, 18 The following have one muscle attached : — 2 Parietal, 2 Lachrymal, 2 Stapes, 2 Trapezoid, 2 Ossa magna (plural of os magnum) 2 Cuboid, 2 Scaphoid. Total, 14 Bones with two muscles attached : — 2 Unciform, 2 Pisiform, 2 Internal cuneiform, 2 External cuneiform, Total, 8 Bones with three muscles : — 1 Frontal (three fairs of muscles), 2 Trapezia* (plural of trapezium), 2 Mallei (plural of malleus). 5 Bones with four muscles : — 2 Palate, 2 Patellze (plural of patella), 1 Coccyx (four pairs of muscles). Total, 5 The two malar (cheek) bones have five muscles attached to each. The clavicle (collar-bone) has six. The sacrum has 8 pairs of muscles, and the two heel-bones have each eight muscles ; the radius and fibula each nine muscles — i.e2 radii and 2 fibulae have each nine muscles attached. The sternum has 9 pairs and one single muscle. The hyoid bone has 11 pairs, and the 2 superior maxillary bones and 2 tibiae have each eleven muscles ; the occipital and sphenoid bone each twelve (twelve pairs) ; the ulna of each fore-arm, thirteen mus- * “A,” at the end of a Latin word is pronounced like “a” in bar. OSTEOLOGY. 33 cles; the inferior maxillary 14 pairs, and the 2 temporal bones each fourteen muscles; the scapula, seventeen; the femur of each thigh, twenty-three ; the humerus of each arm, twenty-five ; and each hip- bone has thirty-six muscles attached to it. Besides these, all the metacarpal bones, the metatarsal, the pha- langes, ribs and vertebrae have muscles attached. Nearly all the mus- cles are in pairs ; only four are single. It may be observed that the muscles attached to mesial bones are pairs of muscles generally. With the exception of the hyoid and the bones of the ear, all the bones articulate with each other. The hyoid does not articulate with any other bone, and the ear-bones only with each other. The ethmoid bone articulates (touches, or connects) with thirteen bones ; the frontal and sphenoid bones articulate each with twelve bones ; the superior maxillary with nine; the os magnum with seven ; and all others with less than seven. Bone is said to be composed of two kinds of tissue, compact and cancellated; but really all bone is porous, and one part is only more compact than another. The cancellated (like lattice-work) tissue is more open, or more porous. In the skull of middle life there are two tables, or plates, of compact bone, one external, the other internal; and between them is some cancellated tissue called the diploe (double). The diploe is spongy, and contains numerous blood-vessels. It might in some cases prevent the fracture of the inner table, and thus increase the degree of protection of the brain. The compact tissue of bone is generally found at the surface or outer part of the bone, and the cancel- lated tissue within its substance. The larger canals and passages for blood-vessels and nerves in the bones were named Haversian canals, from Clopton Havers, their early discoverer. The small canals were called canaliculi (little canals), and are less than one ten-thousandth of an inch in diameter. The smallest canals contain a single capillary vessel; the larger contain blood-vessels, nerves, and marrow. Around each Haversian canal the osseous tissue is arranged in concentric (having one common center) lamellae (little plates), varying in number from eight to fifteen. The lamellae them- selves consist of a delicate network of fibers, coalescing at their point of junction. In and between the little plates that surround the larger canals are minute cavities called lacunae (little lakes, or pools), which contain the bone cell. Besides the concentric lamellae, there are other plates, or layers of bone, which are concentric with the medullary canal, and serve to bind together the various Haversian systems. The layers surrounding the medullary canal of the long bones are termed circumferential (bearing OSTEOLOGY. around) lamellae. Then there are rows of posts or pillars of support between the concentric lamellae, and these have been called interstitial (standing between) lamellae. The Haversian canals are lined by a delicate membrane continuous with the periosteum. The smallest canals extending from the lacunae are filled with the fine processes of the bone cell which fills each lacuna. The bones have many prominences and depressions, each of which is utilized, and many of which take distinctive names, as heads, con- dyles, sutures, tubercles, tuberosities, spines, processes, cavities, fossae, sinuses, etc. One hundred and twenty bones have heads. The heads of the ribs articulate (connect by joint) with the bodies of the dorsal vertebras. The head of the scapula (shoulder-blade) articulates with the head of the humerus. The latter (the humerus) has a second head at the elbow, called the radial head, which articulates with the head of the radius. The head of the ulna is at the lower extremity of the bone near the wrist, and articulates with the triangular fibro-carti- lage which separates it from the wrist-joint. It also articulates with the semi-lunar, or sigmoid, cavity of the radius. The heads of the metacarpal and metatarsal bones and phalanges lie at the opposite extremity from the base. The base of each bone is nearest the wrist or ankle, while the head is the part nearest the ends of the fingers and toes. The base of the metacarpal and metatarsal bones and phalanges is generally concave, while the head is convex, or rounded. The head of the astragalus is the anterior portion, and it articulates with the scaphoid bone. The head of the femur articulates with the cotyloid (cup-like) cavity of the hip. The cotyloid cavity of the hip- bone is also called the acetabulum (vinegar cruse). The head of the tibia is the upper extremity of the bone at the knee, and articulates with the condyles of the femur. The head of the fibula is, also, at the upper extremity of the bone, and articulates with the tibia near the knee, but does not form a part of the knee-joint. The head of the malleus is the upper extremity of the bone, and articulates posteriorly with the incus, being free at its upper part. The head of the stapes articulates with the long process of the incus. We have now described the heads of 120 bones ; viz., 56 bones that compose the phalanges, 24 ribs, 10 metacarpal, 10 metatarsal, and two each of the following: the astragalus, tibia, fibula, femur, radius, ulna, humerus, scapula, malleus, and incus. Six bones have condyles. They are the occipital bone, inferior maxillary, humerus of each arm, and the femur of each thigh. (Condyle signifies knuckle, or knot.) The two condyles of the occipital bone articulate with the cups of OSTEOLOGY. 35 the atlas. The condyle of the inferior maxillary bone, called also the condyloid process, articulates on each side of the head, with the glen- oid (glen-like) fossa of the temporal bone immediately in front of the external ear-passage. The two condyles of the humerus form the internal and external prominences of the elbow, and the two condyles of the femur articu- late with the tibia at the knee. Fig. 7. SIDE VIEW OF THE SKULL. The cranial and facial bones have sutures (seams); but those sutures that connect the cranial bones with those of the face, and the facial bones with each other, have received no special names. The cranial sutures are divided into suttires at the vertex, at the side, and at the base of the skull. Those at the vertex are the ones most 36 OSTEOLOGY. worthy of remembrance. They are the sagittal (arrow), coronal (crown), and lambdoid (like the Greek letter /, shaped like the two contiguous sides of a triangle, which is the shape of the suture). The sagittal suture meets the coronal as the arrow meets the bow, nearly at right angles. A small, rough eminence is called a tubercle ; if broad and rough, a tuberosity. Tubercle and tuberosity are sometimes interchangeable. The femur has two large tuberosities, which take the special names of “trochanter (wheel) major,” and “trochanter minor.” They serve for attachment of muscles which rotate the thigh — the word “tro- chanter” signifying to run round. Other prominent tuberosities are the two tuberosities of the humerus, greater and lesser, situated near the shoulder, one on either side of the bicipital groove, which lodges the long tendon of the biceps (two-headed) muscle ; the tuberosity of the radius, near its head, for the attachment of the biceps muscle ; the internal and external tuberosities at the head of the tibia; and the tuberosity of the ischium, which forms the lowest part of the hip-bone, on which we rest when seated. The most prominent tubercle is the tubercle of the tibia, situated about two inches below the knee-joint, and in front of the bone for the attachment of the ligamentum patellae (ligament of the knee-pan), which is the common tendon for the triceps (three-headed, called also quadriceps) extensor of the leg. The most prominent spines are the spine of the scapula, spine of the pubes, spine of the ischium, and the four spines of the ilium — two anterior and two posterior. The processes of the bones are very numerous, among which we mention here as prominent, the acromion and coracoid of the scapula (shoulder-blade); the alveolar of the maxillary bones for the teeth ; the two coronoid, and the two condyloid, of the inferior maxillary (lower jaw) ; the coronoid process of each ulna, making four coronoid processes ; the two jugular processes of the occipital bone; the two mastoid of the temporal bones ; the odontoid process of the axis ; the olecranon process of each ulna ; the palate process of the palate bone ; the two pterygoid processes of the sphenoid bone; the spinous proc- esses of the vertebrae; the styloid process of each radius, of each temporal, and of each ulna, making six styloid processes; the trans- verse processes of the vertebrae ; and the zygomatic processes of the temporal and malar bones, which together form on each side of the head the zygomatic arch. The prominent cavities of single bones are the cotyloid cavity of the hip, the glenoid of the scapula, and temporal bone, and the sigmoid OSTEOLOGY. 37 cavity of the radius and ulna. The ulna has a greater and a lesser sigmoid cavity. The most prominent fossae (cavities whose entrance is larger than the base) are the glenoid fossa, or cavity, of the tempo- ral bone; the iliac fossa of the ilium; the infra-spinous, and the supra-spinous, of the scapula; the lachrymal (tear), for the lachrymal gland ; the anterior, middle, and posterior fossae (cavities) of the base of the cranium (skull), for the three corresponding lobes (anterior, middle, and posterior lobes) of the brain; the subscapular (under the shoulder-blade), on the anterior or inner side of the scapula, for the subscapularis muscle ; the temporal fossa, formed by aid of five bones, for the temporal muscle ; and the zygomatic fossa, situated below, and on the inner side of the zygomatic arch. The zygomatic arch, or zygoma (yoke), is formed by the union of the zygomatic processes of the temporal and malar bones, and the zygomatic fossa contains the lower part of the temporal muscle, the pterygoid muscles, the internal maxillary artery, and the inferior maxillary nerve. The term “sinus” (a hiding-place, pocket, bay, or gulf) has in medicine three different significations, and has been applied, first, to parts of the nasal cavities ; second, to channels, or canals, for venous blood in the enceph- alon (within the head), and gravid uterus ; and, third, to an abnormal passage leading from a deep-seated abscess, or diseased bone. The term is also applied to the depressions, or cavities, in the walls of the vessel behind the valves at the commencement of the pulmonary artery and aorta, and to a depression in the prostatic portion of the urethra (passage from the bladder); but these are comparatively unimportant. The sinuses of the nasal cavities are the maxillary, sometimes called the antrum (cave) of Highmore, the frontal, the sphenoidal, and the ethmoidal (or ethmoid cells). The sinuses of the pulmonary artery and aorta are called the sinuses of Valsalva. The term crista galli (comb of a cock) is the name of a process rising above the cribriform (sieve-like) plate of the ethmoid bone, for the attachment of the falx cerebri (scythe of the cerebrum) in front. The falx cerebri is a membrane which divides in part the upper brain. The “crest of the ilium ” is the superior margin of the ilium — the highest part of the hip ; the “crest of the tibia” is the anterior sharp edge, called, also, the shin ; and the “ crest of the pubis ” is the edge which forms the upper surface of the bone. One important fissure, the Glaserian, or glenoid fissure, should be mentioned in connection with the bones. It is a narrow slit in the glenoid fossa of the temporal bone, and leads into the tympanum, or middle ear. The names, or epithets, applied to the various processes signify 38 OSTEOLOGY. objects which they resemble. Four processes of the sphenoid are called “ clinoid ” (like a bed), because they resemble, in situation, the four posts of a bedstead before and behind the Sella Turcica (Turk’s seat, or saddle). The coracoid (raven-like) process of the scapula was named by Galen, from its resemblance to a raven’s beak. Processes having a smooth surface for articulation with other bones are called articulating processes. The termination “ oid ” signifies “like,” or resembling; and we have pterygoid (like a wing), odontoid (like a tooth), mastoid (like a nipple), coronoid (crow-like), styloid (like a pencil), cotyloid (like a cup), glenoid (glen-like), etc. A sinus differs from a fossa in having its interior more expanded than the entrance. A foramen is an opening that pierces the bone entirely, or enters deeply into its substance. It is an opening through a bone,— a per- foration. The plural is foramina. The sphenoid bone has five pairs of foramina, and sometimes six. The foramina of bones are numerous. A canal is a channel for the passage of a liquid, blood-vessels, or nerves. Prominent among the canals in the bones are the inferior dental canals (one on each side of the head), on the inner surface of the ramus (branch) of the lower jaw, which transmit blood-vessels and nerves to the lower teeth ; the carotid canals in the petrous portion of the tem- poral bones, which transmit the internal carotid arteries to the brain; the lachrymal (tear) canals, called also nasal canals, or nasal ducts, which convey the tears into the inferior meatus (passage) of the nose; the semi-circular canals of the internal ear; and the spinal, or vertebral, canal for the spinal cord. An epiphysis (growing upon) is a portion of bone, separated from the body of the bone by cartilage, which, in process of time, becomes converted into bone. The epiphysis of a bone is formed by a separate center of ossification. The diaphysis (growing through) is the main, or middle, portion of bone between the epiphyses (plural of epiphysis). In the long bones the diaphysis is the shaft, or middle portion, to which the epiphyses later in life become attached. At birth the epiphyses of all cylindrical bones, with the exception of the lower epiphysis of the femur, and occasionally the upper epiphysis of the tibia, are still unos- sified. The bones of the wrist (carpal bones) are all cartilaginous at birth. The pisiform (peaform) appears latest of the carpal bones, at about the twelfth year. The epiphyses of the bones of the hand and foot appear 39 OSTEOLOGY. about the third to the seventh year, and become completely ossified and united to the diaphyses about the twentieth year. The head of the humerus, at the shoulder, begins to ossify about the second year, and unites with the shaft about the twentieth year. The epiphyses at the elbow become united somewhat earlier,— about the eighteenth year. The femur is developed in about the same time with the humerus; but the head of the femur is joined to the shaft about two years sooner than the condyles at the knee. The condyles at the knee unite with the femur about the twentieth year. The vetebrae are not completely formed till about the thirtieth year of life. The words superior, inferior, anterior, posterior, above, and below, have reference, in anatomy, to the position of the parts in the erect posture of the body. THE INFERIOR MAXILLARY (Lower Jaw). This is the largest bone of the face. It is sometimes called the man- dible (from mandere to chew). It is the only bone that moves dur- ing mastication. It has a body and two rami (branches). The body is curved like a horseshoe, and is nearly horizontal; while the rami are straight, and nearly vertical. The fore part of the body is called the chin, mentum, or genium. The latter term signifies taste, or appetite. The vertical line at the middle of the chin is called the symphysis menti (union of the chin, the part where the two halves unite. The union occurs during infancy). At the lower part of the symphysis is a trian- gular eminence, which is called the mental process. The word men- tum (chin) has the same root as mens (mind) ; and some regard a prominent chin as evidence of intellectual endowment. On the exter- nal surface of the body of the jaw, and just below the root of the second bicuspid tooth, on either side, is the mental foramen, where the mental nerves and vessels emerge from the bone. These two foramina (one on each side of the median line) are about five centimeters (a little less than two inches) apart. On the lower border of the body, just where it joins the ramus, is, usually, a shallow groove, sometimes scarcely perceptible, over which passes the facial artery, one of the branches of the external carotid. The upper border of the body contains the alveoli (plural of alveo- lus), or sockets, for the teeth. In the adult there are sixteen, eight on each side of the symphysis, for the permanent teeth ; in the child of three to six years there are only ten alveoli, and these contain the primary teeth. 40 OSTEOLOGY. The ramus (branch) is thinner than the body of the bone. Its posterior border meets the lower border of the body, and forms the angle of the jaw. The external surface of the ramus is nearly flat, and gives attachment to the masseter muscle. On the middle of the inter- nal surface of the ramus is the entrance to the inferior dental canal for nerves and vessels to the lower teeth. Each ramus is surmounted by two processes, the coronoid, and the condyle. The coronoid is thin and pointed, and gives attachment to the temporal muscle. It is separated from the condyle behind by the Fig. 8. (The dotted lines indicate spaces and position for the attachment of the muscles named.) THE LOWER JAW. sigmoid notch. The condyle articulates with the temporal bone in the glenoid (glen-like) fossa. The lower jaw gives attachment to fourteen pairs of muscles ; and if we reckon the orbicularis oris, which has a few fibers from this bone, and is a single muscle, we shall have in all twenty-nine muscles. Great changes take place in the lower jaw from infancy to old age. Before the teeth appear in infancy, and after their loss in old age, the angle is more obtuse than in middle life. After the. loss of the teeth the bone becomes reduced in size, by the absorp- tion or removal of the alveolar process, so that only the basilar, or lower, part of the bone remains. It is developed at an early period of embryonic life, ossification commencing in this bone and the clavicle about the sixth or seventh week. OSTEOLOGY. 41 THE SUPERIOR MAXILLARY BONE. This bone unites with its fellow of the opposite side to form the upper jaw. Of all the facial bones it is second in size, the lower jaw being largest. It extends vertically from the frontal bone above, along the side of the nose to the lower margin of the alveolar process, which contains the upper teeth. Each bone helps to form the roof of the mouth, the floor and outer wall of the nose, and the floor of the orbit for the eye. Fig. 9. LEFT SUPERIOR MAXILLARY BONE — OUTER SURFACE. It has four processes; the nasal (nose), malar (cheek), palate (roof of the mouth), and alveolar (socket process). The latter contains the upper teeth. The palate process forms a part of the roof of the mouth, and sepa- rates, anteriorly, the cavities of the mouth and nose ; the nasal process runs upward, and forms, in part, the side of the nose ; and the malar process articulates with the malar bone, and helps to form the cheek. It has also four surfaces, and if we reckon the roof of the mouth, Jive. The four usually given are the facial, the posterior, or zygomatic, the superior, or orbital, and the internal. The latter (the internal sur- face) is divided by the palate process into two surfaces, one of which forms part of the roof of the mouth, and the other a part of the nasal 42 OSTEOLOGY. fossa (or cavity). The zygomatic surface (See Fig. 9), along the alveolar process, is continuous with the facial surface, but is separated above from the facial surface by the malar process. The zygomatic surface, although convex, forms part of the zygomatic fossa (cavity). On this surface, which looks backward and outward, are the apertures of the posterior dental canals, which transmit to the teeth the posterior dental nerves and vessels. On the inner margin of this surface is the Fig. 10. LEFT SUPERIOR MAXILLARY BONE — INNER SURFACE. entrance to a groove, which forms in part the posterior palatine canal. (See Fig. io.) This groove is converted into a canal by the palate-bone. It transmits nerves and vessels to the soft palate and roof of the mouth. The anterior palatine canal is nearly parallel with the posterior. Both run obliquely downward and forward, and both transmit nerves and vessels to the palate (roof of the mouth). The anterior palatine canal opens from the nasal fossa into the mouth close to the median line, and just behind the upper incisors (front teeth). It transmits the naso-palatine nerve. Its position is indicated in the figure by bristle. The facial surface of the superior maxillary bone looks forward and outward, and forms part of the face. Its prominent features are: the nasal notch, for the anterior nostril; the incisive fossa, just above the two upper front teeth ; the canine fossa, separated from the incisive by OSTEOLOGY. 43 the canine eminence; and the infra-orbital foramen (opening beneath the orbit), which is the termination of the infra-orbital canal. (See Fig. 9.) The canine (dog) eminence lies in front of the socket of the canine tooth (the dog-tooth, or cuspid). The incisive fossa gives origin to Fig.ii. BONES OF THE FACE — LEFT SIDE. the depressor alae nasi (depressor of the wing of the nose); and the canine fossa to the levator anguli oris (lifter of the angle of the mouth). The infra-orbital (beneath the orbit) canal is sometimes only a groove in the floor of the orbit, but commonly it runs along just beneath the floor of the orbit, commencing at the upper margin of the zygomatic 44 OSTEOLOGY. surface, behind the floor of the orbit. It transmits the infra-orbital nerve and vessels. The infra-orbital canal divides near its middle part, and forms a second canal — the anterior dental canal. The latter may be described as lead- ing from the infra-orbital canal to the upper front teeth. Its entrance is usually concealed from view by the orbital surface of the bone. It trans- mits the anterior dental nerve, one of the branches of the superior maxillary. The orbital surface of the superior maxillary forms the greater part of the floor of the orbit. Its inner margin articulates with three other bones. These are the lachrymal in front, the “ os planum ” (smooth bone) of the ethmoid in the middle, and the orbital process of the palate bone behind. The internal surface of the superior maxillary bone assists largely in forming the cavities of the mouth and nose. A large cavity — the maxillary sinus — is found beneath the floor of the orbit which com- municates with the middle meatus of the nose. This cavity is sepa- rated from the orbit by a very thin plate of bone. It is often called the antrum (cave) of Highmore, its supposed discoverer, although Casserius previously mentioned it under the name of antrum genae (cave of the cheek, or cheek cavity). In some cases the floor of the antrum is pierced by the roots of the first and second molar teeth. Crossing the antrum (“cave”—the maxillary sinus) is one or more projecting laminae (plates) of bone, which serve to strengthen the bone at this part. The cells above these laminae are closed in by the ethmoid and lachrymal bones. The superior maxillary sinus varies greatly in size and shape. In the middle part of the upper portion (the nasal portion) of the internal surface is a deep groove, formed in part by the nasal process of this bone. This groove is converted into a canal by the lachrymal and inferior turbinated bones, and lodges the nasal duct, which conveys the tears from the eye into the inferior meatus of the nose. The superior maxillary articulates with nine bones, and gives attach- ment to eleven muscles. Each superior maxillary articulates with its fellow of the opposite side, and with eight other bones : these are the frontal, ethmoid, vomer, nasal, lachrymal, malar, palate, and inferior turbinated. OSTEOLOGY. 45 THE INFERIOR TURBINATED BONES. These bones, two in number, extend horizontally, on either side, along th*, outer wall of the nasal fossa. Each bone is curled upon Fig. 12. RIGHT INFERIOR TURBINATED BONE — INTERNAL SURFACE. itself, its internal surface convex, and its external surface concave. The upper border is connected to various bones (palate, ethmoid, lachrymal, and superior maxillary) along the outer wall of the nose. Fig. 13. RIGHT INFERIOR TURBINATED BONE — OUTER SURFACE. The lower border is free, and is a little more than one centimeter (about one half inch) above the floor of the nose. This bone divides the middle meatus (passage) from the inferior meatus of the nose. Authors describe three processes — the ethmoidal, lachrymal, and maxillary. It articulates with four bones, as given above. The middle and superior turbinated bones are properly parts of the ethmoid. THE VOMER (Ploughshare). This bone forms the lower and back part of the septum (partition) of the nose. It is often bent, or deflected to one side. The septum is completed in front by the triangular cartilage below and the perpendicular plate of the ethmoid above. In position the vomer is vertical, and extends backward and upward to the body of the 46 OSTEOLOGY. sphenoid. It rests below,, in the median line, upon the roof of the mouth, or, more properly, upon the palate processes ot the superior maxillary and palate bones; thus articulating with two pairs of bones Fig. 14. THE VOMER. and two single bones. It has no muscles attached. Its posterior bor- der is free, and separates the apertures of the posterior nares (nostrils opening from the throat, or pharynx). THE NASAL BONES. The nasal bones, one on each side of the median line, form the bridge of the nose. They extend from the frontal bone above to the Fig- 15- LEFT NASAL BONE INNER SURFACE. lateral cartilage, which helps to form the tip, or base, of the nose, below. Their inner borders articulate with each other in the median line ; their outer borders, one on each side of the nose, articulate with the nasal OSTEOLOGY. 47 Fig. 16. RIGHT NASAL BONE — OUTER SURFACE. process of the superior maxillary (upper jaw) bone, which also forms part of the side of the nose. They also articulate, at the internal bor- der, with the perpendicular plate of the ethmoid. THE LACHRYMAL (Tear) Bones. These two bones, one on either side, are the smallest of the face. They resemble in form and size the finger-nail, and are placed at the anterior and inner part of the orbit. They convert the nasal grooves of the superior maxillary bones into canals for the nasal ducts. Each bone is a thin scale, and, from its form and size, is sometimes called the Fig. 17. LEFT LACHRYMAL BONE — EXTERNAL SURFACE. os unguis (finger-nail bone). It affords attachment to one muscle,—- the tensor tarsi,— sometimes called the muscle of Horner. The muscle 48 OSTEOLOGY. is .6 cent. (J inch) broad and 1.3 cent. (£ inch) long. It divides into two parts at the commissure of the lids, and is inserted into the tarsal cartilages of the eyelids. THE MALAR BONES. The malar (apple) bones, one on each side, are the cheek-bones,— so named from the roundness of the cheeks. They help to form the outer wall and floor of the orbit and part of the temporal and zygomatic fossse. The malar bone, on each side, divides the orbit from the tem- poral fossa, as may be seen by reference to the cranium. It has three Fig. 18. LEFT MALAR BONE — INNER SURFACE. OSTEOLOGY. 49 processes: the orbital, frontal, and zygomatic. The latter meets the zygomatic process of the temporal bone to complete the zygomatic arch. It articulates with four bones, and gives attachment to five muscles. Two of the muscles, the zygomatic major and minor, are inserted into the angle of the mouth and upper lip. THE PALATE BONES. The palate bones take their name from the fact that they form part of the palate (roof of the mouth). They also form the posterior por- tion of the floor of the nose, part of the floor of the orbit, and the inner wall of the antrum (maxillary sinus). Each bone has a palate process, a vertical plate, and an orbital process. The palate process separates, in part, the mouth and nose. It is sometimes called the horizontal plate. Its posterior border affords attachment for the velum palati (veil, or cover, of the palate), often called the soft palate. The vertical Fig. 20. LEFT PALATE BONE — POSTERIOR VIEW. plate runs upward from the palate process to the orbital, along the inner wall of the antrum. It has a groove, which assists in forming the poste- rior palatine canal. The orbital process forms a portion of the floor of the orbit. The palate bone articulates with six bones and gives attach- ment to five muscles. The muscles are the internal and external ptery- goid, the superior constrictor of the pharynx, the tensor palati, and the azygos uvulae. 50 OSTEOLOGY. Fig. 2i. LEFT PALATE BONE INTERNAL VIEW. THE ETHMOID. The ethmoid (sieve-like) bone is the most delicate bone in the body. It is situated at the anterior part of the base of the cranium, between the two orbits at the root of the nose. It consists of the horizontal, or cribriform (sieve-form), plate, the perpendicular plate, and the two lateral Fig. 22. ETHMOID BONE UPPER AND RIGHT SIDES (ENLARGED). OSTEOLOGY. 51 masses. The horizontal plate forms part of the base of the skull, and lies in the ethmoid notch of the frontal bone, between the orbital plates. This part of the bone, the horizontal or cribriform plate, is perforated by several minute foramina, which transmit the olfactory nerves. From these perforations the bone itself and the cribriform plate both take their names. At the middle line of the cribriform, or horizontal plate, is a projection —the crista galli (comb of a cock) —for the attachment of the falx cerebri (sickle, or scythe, of the brain). The latter is a fold, or process, of the dura mater (hard mother), which separates and sup- Fig. 23. ports the two lateral halves of the upper brain. The perpendicular plate of the ethmoid forms a considerable part of the septum (partition) of the nose. The lateral masses of the ethmoid form the inner walls of the orbits, and contain the anterior and posterior ethmoidal cells, which form parts of the nasal cavities. The anterior ethmoidal cells communicate with the middle meatus of the nose, while the posterior ethmoidal cells communicate with the superior meatus of the nose. The anterior eth- moidal cells also communicate in the adult with the frontal sinuses. The outer smooth surface of each lateral mass, which forms the inner wall of each orbit, is called the “ os planum ” (smooth, or level bone). The ethmoid articulates with thirteen bones (sometimes fifteen), all the bones of the face except the malar and lower jaw, and two of the skull,— sphenoid and frontal. The two “sphenoidal turbinated bones” are usually, in the adult, joined to the body of the sphenoid bone, but are sometimes separate, in which case the ethmoid articulates with fifteen bones. The two sphenoidal turbinated bones are called also “sphenoidal spongy bones.” ETHMOID BONE VERTICAL SECTION IN THE MEDIAN LINE (ENLARGED). 52 OSTEOLOGY. THE SPHENOID. The sphenoid (wedge-like) bone is situated at the anterior part of the base of the skull, and extends outward on either side to the temple. It assists in forming the cavity of the cranium (skull), the two orbits, the two nasal fossae (cavities of the nose), the two temporal fossae, the two zygomatic fossae, the two spheno-maxillary fossae, the two pterygoid fossae, the two sphenoidal fissures, the two spheno-maxillary fissures, and the two pterygo-maxillary fissures. The sphenoidal fissure is the “ foramen lacerum anterius ” (anterior lacerated opening) of Gray, and the “foramen lacerum superius ” (supe- rior lacerated opening) of Dunglison. It opens into the orbit between the greater and lesser wings of the sphenoid, and transmits several Fig. 24. SPHENOID BONE—ANTERIOR SURFACE. pairs of cranial nerves. The spheno-maxillary fissure also opens into the orbit, and forms a communication between the orbit and three fossae, — the temporal, zygomatic, and spheno-maxillary. The sphenoid articulates with all the remaining bones of the cra- nium, and with five of the face (the two malar, the two palate, and the vomer). It has a body, two greater wings, two lesser wings, and two wing-like (pterygoid) processes. Besides the sphenoidal fissure and one canal,— the Vidian,— there are on either side four, and sometimes five, other foramina, which perforate the sphenoid bone. The remaining OSTEOLOGY. 53 four are the “ optic,” for the optic nerve and ophthalmic artery; the foramen rotundum (round opening) for the superior maxillary nerve (second division of the fifth cranial) ; the foramen ovale (oval opening), for the inferior maxillary nerve (third division, or branch, of the fifth cranial) ; and the foramen spinosum, for blood-vessels and filaments of the sympathetic system of nerves. The Vidian canal, which passes through. the body of the sphenoid at the root of the pterygoid process, transmits the Vidian nerve, which supplies a part of the septum (parti- tion) of the nose, and divides into two branches — the large petrosal and carotid branches. In the body of the sphenoid are two large, irregular, and unsymmet- rical cavities, called the sphenoidal sinuses, which communicate with the Fig- 25. SPHENOID BONE SUPERIOR, OR CEREBRAL SURFACE. superior meatus of the nose. The sphenoid gives attachment to twelve pairs of muscles. These include all the muscles of the orbit except the inferior oblique ; three muscles of mastication, viz., the temporal, exter- nal, and internal pterygoid; two muscles of deglutition, viz., the tensor palati and the superior constrictor of the pharynx, and the laxator tym- pani of the middle ear. The other points of the sphenoid which should be mentioned are the optic groove, which supports the commissure of the optic nerves; the olivary process, just behind the groove ; the sella Turcica (Turk’s seat, 54 OSTEOLOGY. or saddle), a deep and smooth cavity on the upper surface of the body of the bone, which lodges the pituitary body of the brain ; the anterior and posterior clinoid (bed-like) processes, situated like four bed-posts around the sella Turcica; the rostrum of the sphenoid, received into a depression in the vomer ; the spine, or spinous process, of the sphenoid at the lower part of the external surface of the greater wing, which gives attachment to the external lateral ligament of the jaw, and laxator tym- pani (loosener of the drum) muscle ; the orbital surface of the greater wing, assisting to form the outer wall of the orbit; and the internal and external pterygoid plates of the pterygoid processes, which unite partially in front, on either side, and form the pterygoid fossce. The external pterygoid (wing-like) plate on either side gives attachment, by its outer and anterior surface, to the lower head of the external pterygoid muscle, and by its inner surface, which forms part of the pterygoid fossa, to the internal pterygoid muscle. The internal pterygoid plate is narrower and longer, and curves outward at its extremity in a hook-like (ham- ular) process, around which turns the tendon of the tensor palati (stretcher, or tightener, of the palate—the soft palate, or veil of the palate) muscle. The anterior surface of the pterygoid process forms the posterior wall of the spheno-maxillary (sphenoid bone and upper jaw) fossa, and supports Meckel’s (John Frederick Meckel) ganglion. THE TEMPORAL BONES. The temporal (signifying “ time,” because the first gray hairs usually appear in this region) bone is situated on either side of the head around, and mostly above, the external ear-passage. It derives importance from the fact that it contains the organ of hearing. Each bone consists of three portions: the squamous (scaly), mastoid (nipple- like), and petrous (rocky). The squamous and mastoid portions form part of the outer wall of the cranium ; but the petrous portion extends inward, and forms a part of the base of the cranium. The squamous portion is the upper part; is thin and tranlucent, and articulates with the parietal bone, forming the squamous suture. Its outer surface forms part of the temporal fossa ; its inner surface is continuous with the upper surface of the petrous portion. Projecting from the outer surface of the squamous portion, near its base, is a long curved process, called the zygomatic (yoke) process. This process extends forward, and unites with the malar bone to form the zygomatic arch beneath which plays the temporal muscle. The OSTEOLOGY. 55 zygomatic process is connected to the temporal bone by three roots, although only one is discoverable when viewing it from above. Dun- glison mentions only two roots of the zygomatic process. The middle root, together with the auditory process, separates the glenoid (glen- like) fossa from the external ear-passage. The auditory process is a curved plate of bone, surrounding the lower part of the circumference of the external ear-passage, and to which is attached the cartilage of Fig. 26. LEFT TEMPORAL BONE — INNER SURFACE. the external ear (the pinna). The superior border of the zygomatic process gives attachment to the temporal fascia (band or bandage). The inferior border and inner surface of the process gives attachment to the masseter (chewing) muscle. The latter extends to the angle of the lower jaw. The glenoid fossa is situated one or two centimeters (half an inch) in front of the external ear-passage, and between the anterior and mid- dle roots of the zygomatic process. It is divided by the Glaserian fissure into two parts. The anterior part is occupied by the condyle of the lower jaw; the posterior lodges a portion of the parotid (near the ear) gland. 56 OSTEOLOGY. The Glaserian fissure leads into the tympanum, or middle ear, and transmits the tympanic artery and a very small muscle — the laxator tympani (loosener of the drum; more properly of the membrane, or head of the drum). The squamous portion of the temporal bone articulates in front, by a serrated (saw-tooth) edge, with the great wing of the sphenoid, and below, with the lower jaw. The mastoid portion is situated at the back part of the bone, behind and beneath the squamous portion, and Fig. 27. LEFT TEMPORAL BONE OUTER SURFACE. behind the external ear-passage. This portion of the bone takes its name from a large conical projection at its outer and lower part, called the mastoid (nipple-like) process. It forms the prominence just behind the ear, and contains at puberty the mastoid cells that open by one or two orifices into the middle ear, or tympanum. It also gives attachment to several muscles, one of which, the sterno-mastoid (also called sterno-cleido-mastoid), becomes prominent in the neck when the head is turned toward the opposite side. On the inner and posterior OSTEOLOGY. 57 side of the mastoid process are two grooves,— a deeper external one, and a shallow and more internal one,— for the attachment respectively of the digastric (two-bellied) muscle and for the bed of the occipital artery. On the inner surface of the mastoid portion is a deep groove, for the lateral sinus, and a foramen, which transmits a vein to the sinus. The foramen varies in size and position, but being generally found m the mastoid portion of the temporal bone, it is called the mastoid for- amen. The mastoid portion articulates above with the parietal bone, and below with the occipital. The petrous portion (pars petrosa) of the temporal bone, named from its density and hardness, is in the form of a truncated pyramid, lying upon its side, and wedged in at the base of the skull between the sphenoid and occipital bones. Its imperfect apex, rough and uneven, is received into the angular interval between the spinous process of the sphenoid and the basilar process of the occipital bone, and forms the posterior and outer boundary of the foramen lacerum medium (middle lacerated opening). The latter is closed by cartilage, and forms a kind of fontanel (little fountain) at the base of the brain. There are at the base of the brain three pairs of these lacerated foramina. They are designated by Gray, anterior, middle, and posterior ; and by Dun- glison, superior, anterior, and posterior. The anterior of Gray is the su- perior of Dunglison, and is called also the sphenoidal fissure, from its position between the wings of the sphenoid. The latter, sphenoidal fissure, is the better term, and avoids confusion. The middle lacerated foramen is in close connection with the carotid canal, and, being closed by cartilage, is less frequently mentioned. The posterior lacerated fora- men (foramen lacerum posterius) is called, also, the jugular foramen, because it transmits the internal jugular vein in connection with three cranial nerves. The petrous portion of the temporal bone projects inward and for- ward, and contains, in its interior, the essential parts of the organ of hearing. The external ear-passage (meatus auditorius externus) enters the base of the pyramid formed by this portion of the bone. The in- ternal ear-passage (meatus auditorius internus) is on the posterior sur- face of the petrous portion near the apex of the pyramid. On the upper (or anterior) surface is an eminence which covers the superior semi-circular canal of the internal ear. In front of the eminence are one or two grooves, and also an opening (hiatus Fallopii) for the petro- sal (rocky) branch of the Vidian nerve. Near the apex of the pyramid, but external to it, is the termination of the carotid canal for the internal carotid artery. This canal is sinu- 58 OSTEOLOGY. ous, turning almost a right angle in this portion of bone. As the artery- enters the canal it ascends, but quickly turns forward. As we look into the canal at its termination, we see from the front two other canals; one quite small (the canal of Huguier), for the tensor tympani muscle (stretcher or tightener of the drum) and chorda tympani (cord of the drum) nerve, and a larger one for the Eustachian tube. The chorda tympani passes in at the canal of Huguier, across the tympanum and out at the stylo-mastoid foramen. These canals both lead to the middle ear. The small canal (of Huguier) for the nerve and muscle of the drum, lies on the inner and upper side of the canal for the Eustachian tube. The posterior surface of the pyramid, formed by the petrous portion, is continuous with the inner surface of the mastoid portion of the bone. The most prominent feature of the posterior surface is the large orifice opening into the internal ear-passage, for the auditory and facial nerves and auditory artery. The internal ear-passage is a short canal, and runs directly outward. The end of the canal is closed by a vertical plate, which is perforated by minute openings for filaments, or branches of the nerves and vessels. The inferior surface, rough and irregular, presents the opening of the carotid canal (already mentioned, as its termination is at the upper surface, or in front of it) ; a large, smooth depression — the jugular fossa ■—for the internal jugular vein; the styloid process,— a long, sharp spine, of variable size and shape,— for the attachment of three muscles and two ligaments ; and three or four small foramina, for blood-vessels and nerves. The stylo-mastoid foramen at the base of the styloid process transmits the facial and chorda tympani nerves. This foramen derives some importance from the fact that the prin- cipal nerve which it transmits controls all the muscles of the face, fifty-three in number, and other parts besides. The course of the facial nerve from the internal ear-passage through the petrous portion of the temporal bone to the stylo-mastoid foramen is curved, and the curved canal is improperly called the “ aquaeductus Fallopii ” (water-canal of Fallopius). Facial canal would be a better name. The foramina for Arnold’s and Jacobson’s nerves are near the jugula fossa, but are almost too small to be noticed. Arnold’s nerve is the auricular branch of the pneumogastric, and Jacobson’s is the tympanic branch of the glosso- pharyngeal. The petrous portion of the temporal bone articulates with the occip- ital and sphenoid bones. It also contains within the tympanum three small bones, which are described with the ear. The entire temporal bone articulates with five bones, and gives OSTEOLOGY. 59 attachment to fourteen muscles. It has in all fourteen foramina that have been described. For convenience of reference we give a list of their names and uses. On the outer surface we have the external ear- passage (meatus auditorius externus), that receives vibrations of air, and conducts them to the membrane that closes it; the mastoid foramen,—- not constant,— for a vein ; the auricular fissure in front of the mastoid process, for the auricular branch of the pneumogastric nerve ; and the Glaserian (of Glaser) fissure, for the laxator tympani muscle and tym- panic branch of the internal maxillary artery. On the inner surface we have the internal ear-passage (meatus auditorius internus), for the facial and auditory nerves; the hiatus Fallopii, for the petrosal branch of the Vidian nerve; a smaller opening external to the latter for the smaller petrosal nerve ; and a small slit near the central part of the posterior surface of the petrous portion, almost hidden by a thin plate of bone, that transmits, through the aquaeductus Vestibuli, a small artery and vein to the vestibule of the internal ear. On the inferior surface we have the carotid canal, for the internal carotid artery ; the stylo- mastoid foramen, for the facial nerve and chorda tympani nerve; a canal for Jacobson’s nerve ; the aquaeductus cochleae, for a little vein from the cochlea ; a canal for the Eustachian tube ; and, lastly, a smaller canal (canal of Huguier), for the entrance of the tensor tym- pani muscle and chorda tympani nerve. It may be observed that the chorda tympani nerve enters the tem- poral bone at two points: it passes in at one point and out at the other. The temporal articulates with five bones, and gives attachment to fourteen muscles. THE FRONTAL BONE. This bone takes its name from its position in the forehead. It is in part vertical, and in part horizontal. The horizontal portions, called the orbital plates, form the vaults of the two orbits above the eyeballs, and support the anterior lobes of the brain. Between the orbital plates is the ethmoid notch, in which the cribriform plate of the ethmoid com- pletes the anterior portion of the base of the skull. The upper and outer margin of each orbit is called the supra-orbital arch (arch above the orbit). Near the middle of this arch, but somewhat nearer the nose, is the supra-orbital notch, or foramen (sometimes a notch, or groove, and sometimes a foramen) for the supra-orbital vessels and nerve. Between the two supra-orbital arches is a rough triangular margin,— the nasal notch,— which articulates with the nasal bones and nasal 60 OSTEOLOGY. processes of the superior maxillary bones. Above the nasal notch, and extending outward, somewhat over the arch on either side, the frontal bone consists of two plates, or tables, which contain, in the adult, two irregular cavities — the frontal sinuses. These are lined with mucous membrane, and communicate by the infundibulum (a funnel-shaped passage), with the middle meatus on either side of the nose. The supra-orbital arch terminates externally in the external angular process Fig. 28. FRONTAL BONE — OUTER SURFACE. which articulates with the malar bone. The two parietal bones articu- late with the posterior and upper portion of the frontal bone, and form the coronal suture. In infancy there is a frontal suture running from the root of the nose upward, in the median line to the anterior fonta- nel (little fountain). After a few years the frontal suture is usually obliterated, and the two lateral halves of the early frontal bone become united into one. In rare cases the frontal suture is permanent, in which case the subject has two frontal bones instead of one. The OSTEOLOGY. 61 Fig. 29. FRONTAL BONE—INNER SURFACE. Fig. 30. FRONTAL BONE AT BIRTH. 62 OSTEOLOGY. Fig. 31. SKULL AT BIRTH, SHOWING THE ANTERIOR FONTANEL AND SUTURES. frontal bone articulates with twelve bones, and affords attachment to three pairs of muscles. The three muscles on either side are the tem- poral, corrugator supercilii, and orbicularis palpebrarum. THE PARIETAL BONES. The parietal (wall) bones, two in number, form the sides and roof of the skull. They meet in the median line at the top of the head, and form the sagittal (arrow) suture, which extends from the frontal to the occipital bone. Each bone is nearly quadrilateral in form, convex with- out and concave within. Its four borders are named, respectively, upper, lower, anterior, and posterior. The upper borders articulate with each other, the lower with the temporal bone on either side, the anterior with the frontal, and the posterior with the occipital bone. Each bone also articulates at the temple with the greater wing of the sphenoid. The lower border is beveled, except a small portion behind that articulates with the mastoid portion of the temporal bone, and is overlapped by the squamous portion of the temporal bone and tip of the great wing of the sphenoid. The anterior border of each bone is ser- rated (like saw-teeth), and forms half of the coronal suture, by its articu- lation with the frontal bone. The posterior border is also serrated, and the two bones, united closely with the occipital bone, form the lambdoid (A-like) suture. The latter is named from its resemblance to the Greek letter “lambda” X. The lower third of the external surface of each bone helps to form the temporal fossa for the attachment of the temporal muscle, which is inserted into the coronoid process of the lower jaw, and is one of the chief muscles of mastication. Fig. 32. LEFT PARIETAL BONE — OUTER SURFACE. Fig- 33- LEFT PARIETAL BONE — INNER SURFACE. 64 OSTEOLOGY. The concave internal surface of the parietal bone is marked by numerous furrows for the ramification of the meningeal arteries, which feed the meninges (membranes) of the brain. Each parietal bone articulates with its fellow and four other bones, as given above, and affords attachment to one muscle — the temporal. THE OCCIPITAL BONE. (Named from its prominence at the back of the head, which receives a blow given in that direction.) The occipital bone forms the back part of the skull, and also the posterior portion of its base. Being a flat bone it has two surfaces, an outer and inner. The outer surface is convex; the inner, concave. Fig- 34- OCCIPITAL BONE — OUTER SURFACE. It has four borders and four angles. The two lateral angles separate the upper from the lower borders. The principal points to be noted upon the outer surface, are the OSTEOLOGY. 65 occipital protuberance, the external occipital crest, the foramen mag- num (great opening), the two condyles, the two anterior condyloid fo- ramina, the two jugular processes, the basilar process, and the pharyn- geal spine. Authors also mention four curved lines — two superior and two inferior, passing outward from the protuberance and crest. The pharyngeal spine is a mere tubercle, near the center of the under surface of the basilar process, but it marks the point of attach- ment of the superior constrictor muscle of the pharynx (throat), which is one of the muscles of deglutition (swallowing). The basilar process projects forward from the foramen magnum (great opening), at the base of the brain, to meet the body of the sphenoid bone. The occipital protuberance, situated in the median line, midway between the summit (superior angle) of the bone and the foramen magnum, itself a small tubercle, forms attachment for the ligamentum nuchse (ligament of the nape of the neck), which in quadrupeds is a very strong elastic ligament for the support of the head, but in man is only a rudiment. The external occipital crest extends along the median line from the occipital protuberance to the foramen magnum. The foramen magnum transmits the spinal cord, the spinal accessory nerves, and the vertebral arteries. It is an opening three centimeters (more than an inch) in diameter. The condyles lie on either side, somewhat anteriorly, of the foramen magnum, and articulate with the cups of the atlas (first cervical vertebra). To the inner borders of the condyles are attached the check ligaments, which extend to the odontoid (tooth-like) process of the axis (second cervical vertebra), and serve to limit rotation of the head. The check ligaments are also called odontoid ligaments. The two anterior condyloid foramina may be seen just above and in front of the condyles, their names indicating their position. They are sometimes double on each side. They transmit the hypoglossal nerves. The jugular processes — one on each side — lie outside the condyles, and form the back part of the jugular foramen, which transmits on either side the internal jugular vein and three cranial nerves (the glosso-pharyngeal, pneumogastric, and spinal accessory). The jugular foramen is also called the “foramen lacerum posterius” (posterior lacerated opening). The temporal bones, which articulate with the inferior borders of the occipital bone, form the anterior part of the jugular foramen. The basilar process of the occipital bone becomes united to the body of the sphenoid about the twentieth year of life. The two superior borders of the occipital bone articulate with the two parietal bones, and form the lambdoid suture. At the junction of this suture with the sagittal, is found the posterior fontanel (little foun- OSTEOLOGY. tain), where the beating of the brain may be felt during the first year of life. The two inferior borders articulate with the temporal bones. Upon the inner surface of the occipital bone we notice four cavities (fossae), separated by crucial ridges, which intersect nearly opposite the external occipital protuberance. The two superior fossae receive the posterior lobes of the cerebrum (front, or top brain), and the two inferior receive the lateral lobes of the cerebellum (back, or little Fig- 35- OCCIPITAL BONE INNER SURFACE. brain). Near the internal protuberance is a smooth depression, where several large venous channels meet, which is called the “torcula Herophili (press of Herophilus). The large groove upon the upper surface of the basilar process is called the basilar groove. It lodges OSTEOLOGY. 67 the pons Varolii (bridge of Varolius) and the medulla oblongata (oblong medulla, or marrow),— both important parts of the brain. The pons lies at the anterior and upper part of the basilar groove ; while the medulla oblongata lies at the lower part, and forms the upper extremity of the spinal cord. The occipital articulates with six bones, and gives attachment to twelve pairs of muscles. Five of these twelve pairs are recti (plural of rectus, meaning straight) muscles, making altogether ten straight mus- cles at this part of the head and neck. We have also eight straight muscles of the two orbits, two of the abdomen, and two of the thigh. The bones articulating with the occipital are the atlas, sphenoid, two temporal, and two parietal. HYOID BONE. The hyoid bone (named from its resemblance to the Greek letter “y”), or os linguae (bone of the tongue) as it is sometimes called, is situated at the base of the tongue in a plane directed downward and forward. It may be felt high up in the neck, just above the thyroid cartilage (Adam’s apple). It is suspended from the styloid process of the temporal bone, on either side, by a slender band,— the stylo-hyoid Fig. 36. HYOID BONE — ANTERIOR SURFACE. ligament. It consists of a body and two pairs of cornua (horns), the greater and the lesser cornua. It gives attachment to eleven pairs of muscles—six pairs coming from above, three from below, and two lat- erally. Eight of these eleven muscles take their name, in part, from the hyoid bone. They are enumerated in the order given above; viz., hyo-glossus, genio-hyo-glossus, genio-hyoid, mylo-hyoid, digastric, and lingual; the sterno-hyoid, omo-hyoid, and thyro-hyoid; and the stylo-hyoid and middle constrictor of the pharynx. 68 OSTEOLOGY. NASAL CAVITIES, OR FOSSiE. The nasal cavities, two in number, one on either side of the median septum, are communicating air-passages; and in the adult include the sinuses, or cavities, of the frontal, ethmoid, sphenoid, and superior max- illary bones. The internal wall of each cavity, or nasal fossa, is called the septum narium (partition of the nares, or nostrils), and is formed chiefly by the perpendicular, or central plate of the ethmoid, the vomer, Fig- 37- INNER WALL, OR SEPTUM, OF THE NOSE. and the triangular, or septal cartilage, which completes the septum of the nose at its tip, or lower end. The septum is occasionally perforated, and is not always in the median line. The anterior and posterior open- ings of the nasal cavities, or fossae, are called, respectively, the anterior and posterior nares (nostrils). The latter open into the throat (pharynx), the former upon the face. The anterior nares lie in a plane below the floor of the nasal cavity, so that the alae (wings) and tip of the nose must be raised somewhat, in order to expose to view the floor and infe- rior meatus of the nasal cavity. Forceps for extracting growths and OSTEOLOGY. foreign bodies from the nose, can be best opened in the vertical plane, since the cavity is narrower in the lateral direction. Each nasal fossa is partially divided by the turbinated bones into three divisions, or pas- sages, and these passages are called, respectively, the superior, middle, and inferior meatus (passage). Each meatus, on either side, lies just below its corresponding turbinated bone. The superior meatus is situ- ated just beneath the superior turbinated bone (really the turbinated Fig. 38. OUTER WALL OF THE NASAL FOSSA (CAVITY) process of the ethmoid bone). The superior meatus is very short, and communicates with the posterior ethmoidal cells, and also with the sphenoidal sinus on either side. The middle meatus communicates with the anterior ethmoidal cells, the frontal sinus, and the maxillary sinus. The inferior meatus, longer than the others, communicates with the lachrymal sac through the nasal duct. The turbinated bones are also called spongy bones. The funnel-shaped passage from the frontal sinus on either side to the middle meatus of the nose, is called the infundibulum. The plural is infundibula (funnel-shaped). Fig. 39- base OF THE SKULL EXTERNAL, OR UNDER SURFACE. OSTEOLOGY. 71 The frontal sinuses do not exist in children, since the tables of the skull at this part do not begin to separate until the age of puberty, and the sinuses seem to be formed at the expense of the inner wall of the cranium, as the brain recedes. The sphenoidal sinuses are also absent in early youth. VERTEBRAL COLUMN. The vertebral, or spinal, column, is improperly called the ‘'back- bone,” or “spine.” (See Fig. 6.) It contains twenty-four bones and extends from the occipital bone of the head to the sacrum of the pelvis. Each bone is called a vertebra (plural, vertebrae). This word signifies “to turn,” and gives name to the first great division of the animal king- dom. The vertebrata (vertebrate animals) include all animals that have a vertebral or spinal column. All other animals belong to the inverte- brata (invertebrate animals.) Mammals, birds, reptiles, and fishes are vertebrate animals. Mol- lusks, radiates, and articulates are invertebrate — have no spinal col- umn. Some authors consider the sacrum and coccyx as a part of the vertebral column, and thus reckon thirty-three vertebrae. But in the adult the five original pieces of the sacrum become united, and can no longer be called vertebrae ; and the four of the coccyx also become ossified as one. The spinal column forms a single pillar of support for the head, trunk, and upper extremities. It protects the spinal cord by inclosing it in a bony canal. Its average length is five or six decimeters, or about one third the height of the person. Seen in pro- file, or viewed from the side, it has three curves, bending forward in the neck and loins, and backward in the chest. These curves give greater elasticity to the column, and greater security to the spinal cord. Viewed in front the column is naturally vertical; and a lateral curvature (although somewhat common) is a deformity. The bodies of the vertebrae become broader as we descend the neck; then slightly narrower in the upper dorsal region ; then grad- ually widen to the base of the sacrum. The width of the column between the extremities of the transverse processes, or from side to side, is greatest at the first cervical, first dorsal, and the five lumbar vertebrae ; small at the second cervical and last dorsal vertebra, and from these points gradually increases toward the first dorsal vertebra. There are seven cervical (neck) vertebrae, twelve dorsal (back), and five lumbar (loins), all numbered, each region separately, from above downward. The cervical region forms in length about five parts, the dorsal eleven, and the lumbar seven 72 OSTEOLOGY. Fig. 40. THE ATLAS. parts. The first, second, and seventh cervical vertebrae take distinct- ive names, and are called, respectively, the atlas, axis, and vertebra prominens. The atlas supports the head, and takes the name of the giant in mythology who carried the world on his shoulders. The axis takes its name from the tooth-like (odontoid) process around which the Fig. 41. A CERVICAL VERTEBRA. THE SPINOUS PROCESS IS BlElD. atlas revolves in part. The vertebra prominens (prominent vertebra) is thus named on account of the length of its spinous process, which makes it very prominent, and easily distinguished at the base of the neck between the shoulders. Each vertebra, except the atlas, which has no body, consists of a body, an arch (or spinal foramen), and seven processes — four articular processes, two transverse, and one spinous. OSTEOLOGY. 73 The bodies of the vertebrae increase in size and thickness from above downward ; and in position are in front of the spinal cord. Each body has an upper, lower, anterior, and posterior surface. The upper and lower surfaces are slightly concave, and roughened for firmer attachment of the elastic discs that intervene. These elastic discs are often called the intervertebral substances. They are composite (fibro- cartilaginous) in structure, but firm and elastic. The anterior surface of the body of each vertebra is convex from side to side, and extends, in the lower part of the column, two thirds of the way around the body, to the pedicle (footstalk), which separates it from the posterior surface of the body. The posterior surface of each body forms the anterior part of the spinal canal, and is slightly concave from side to side. Fig. 42. VERTEBRA PROMINENS — SEVENTH CERVICAL. The arch of each vertebra, except the atlas, which has two arches, forms the greater part of a large foramen, which transmits the spinal cord. The foramen is called the spinal, or vertebral foramen ; and the canal which these foramina form when the vertebrae are placed in position, is called the spinal, vertebral, or neural (nerve) canal. The arch is formed of two pedicles (footstalks) and two laminae (plates). The pedicles spring, one on either side, from the posterior surface of the body, and extend outward and backward to meet the laminae. The pedicle is the portion of bone between the body and the transverse process, and the lamina connects the transverse with OSTEOLOGY. the spinous process. The two laminae (plates) unite behind the arch, to form the spinous process. The two arches of the atlas are the anterior and posterior. These two arches form about three fifths of the circumference of the atlas, and with the lateral masses inclose a large space occupied by the spinal cord and odontoid process of the axis (second cervical vertebra). The cord is separated from the bony process of the axis by the transverse ligament, which, in the recent state, divides the large foramen of the atlas into an anterior and pos- terior space. The posterior space corresponds to the spinal foramen. The articular processes form the joints of the vertebrae. They are situated at the junction of the pedicles with the laminae. There are Fig- 43- A DORSAL VERTEBRA two articular processes, an upper and lower, on either side. Their ar- ticular surfaces vary greatly in direction in different regions, and the articulating facets (little faces,—another name for the articular sur- faces) of the upper and lower processes in all the vertebrae, except the last dorsal, look in exactly opposite directions, since the lower processes of each bone articulate with the upper processes of the bone below, and, vice versa, the upper of each bone articulate with the lower of the bone above. In the cervical region the upper facets are, at first, nearly horizon- tal, but grow more and more oblique as we descend, until we reach the last dorsal, whose upper facets are nearly vertical, and looking almost OSTEOLOGY. 75 directly backward. The lower articulating facets of the last dorsal vertebra change direction, to correspond with those of the lumbar region, and look almost directly outward toward each side. They are embraced by the upper processes of the first lumbar vertebra, which look almost directly inward, as do all the upper articulating surfaces of the lumbar vertebras. The transverse, or lateral processes, project outward from the sides of the arch. In the neck the atlas (the first cervical vertebra) has the longest transverse processes, and the axis (the second cervical vertebra) the shortest. From the axis to the first dorsal vertebra the transverse Fig. 44. A LUMBAR VERTEBRA. processes gradually increase in length ; from this point to the last dorsal they diminish in length, and again increase to the last lumbar vertebra, where they are nearly as wide as the sacrum. In viewing the spinal column of the skeleton from behind, we see the spinous processes in the median line, the laminae each side, and also the transverse processes; and from the front we see the bodies of the vertebrae, and projecting from behind them the extremities of the transverse processes, except in the dorsal region, where the ribs lie in front, and conceal the transverse processes. The tranverse processes of the six upper cervical vertebrae, and sometimes, also, the seventh, are perforated by a foramen (the trans- verse), which transmits the vertebral artery and vein. They are also grooved superiorly for cervical nerves, and are bifid at their extremity. The spinous processes project backward from behind the arch. These are also bifid in the cervical region. The spinous processes of the sec- ond and seventh cervical vertebrae are more prominent than those between them, and can be distinctly felt in the neck. On either side of the spinal canal are foramina, the intervertebral (between the vertebrae) 76 OSTEOLOGY. for the passage of the spinal nerves. These are formed by the appo- sition of the notches upon the upper and lower borders of the pedicles of contiguous vertebrae. The third cervical (neck) vertebra corresponds (is in the same hori- zontal plane) with the bifurcation (division into the internal and external carotid) of the common carotid artery and the upper end of the larynx (the organ of voice). The fifth cervical marks the lower end of the larynx and pharynx (throat), and the upper end of the trachea (windpipe) and oesophagus (gullet). The second lumbar vertebra marks the plane of the crura (legs) of the diaphragm, the termination of the spinal cord in the cauda equina (horse’s tail) and the commencement of the thoracic duct (large lym- phatic duct that passes through the thorax). The fourth lumbar vertebra marks the termination of the aorta (the great trunk of the systemic arteries). At birth each vertebra has three separate pieces of bone,— one for each lamina and its processes, and one for the body,— and is completely formed about the thirtieth year of life. THE SACRUM. The sacrum (sacred) is situated at the lower part of the vertebral column, and forms the posterior wall of the pelvis. The entire weight of the head, trunk, and upper extremities rests upon it as upon the keystone of an arch. It is triangular in form, with its base directed upward, and helps to form the pelvis (basin). It is inserted like a wedge between the hip-bones, and appears like five consolidated ver- tebrae. It is described as having four surfaces — two lateral, an ante- rior, and a posterior ; a base, an apex, and a canal. It has, also, upon both the anterior and posterior surfaces, four pairs of sacral foramina (openings in the sacrum), distinguished as anterior and posterior sacral foramina. These transmit filaments of the cauda equina (horse’s tail) from the sacral canal. The latter is continuous with the spinal canal. The upper portion of each lateral (side) surface articulates with the hip-bone (os innominatum), and is called the auricular surface, from its resemblance to the external ear (auricle). The anterior surface is concave and smooth, for the reception of the pelvic organs. It is also called the pelvic surface. The posterior surface is convex and uneven. At its upper border are two articulating processes, which embrace the lower articular processes of the last lumbar vertebra. OSTEOLOGY. 77 Fig- 45- THE SACRUM ANTERIOR, OR INNER SURFACE. The base of the sacrum is sometimes called the vertebral surface, as it articulates with the intervertebral substance of the last lumbar vertebra. It projects forward at its middle part, and forms the “prom- Fig. 46. THE COCCYX. 78 OSTEOLOGY. ontory ” of the sacrum. The apex articulates with the coccyx below. The sacrum becomes consolidated and complete about the twenty-fifth year, or later. It articulates with four bones, and gives attachment to eight pairs of muscles. The muscles are the pyriform, coccygeus, iliacus, gluteus maximus, erector spinae, multifidus spinae, extensor coccygis (not constant), and latissimus dorsi. The coccyx (cuckoo, whose bill it is said to resemble), or rump bone, consists of four or five segments of bone, or rudimentary ver- tebrae. The gradual diminution in the size of these bones gives to the coccyx a pyramidal form, whose base articulates with the sacrum. It gives attachment to four, and sometimes five, muscles. The four • muscles of the coccyx are the coccygeus, on either side, the gluteus maximus behind, the levator ani in front, and the sphincter ani at the apex. At a late period of life the coccyx often becomes joined to the end of the sacrum. THE COST.® (Ribs). The ribs (costae, singular, costa) are 24 in number, 12 on each side. They are situated obliquely at the sides of the chest. They are num- bered from above downward, the first being situated at the base of the neck. The eleven intervals between them are called intercostal (between the ribs) spaces. The first seven ribs are called true ribs, because they are connected to the sternum, each by a separate inter- Fig. 47. A TRUE RIB (costa) REDUCED IN SIZE. vening cartilage (the costal cartilage). The remaining five are not connected directly with the sternum, and are called false ribs. Of these, the three adjoining the true ribs — the eighth, ninth, and tenth — are connected by cartilage to the cartilage of the seventh rib; and the lower two, the eleventh and twelfth, are left free at their anterior OSTEOLOGY. 79 extremity, and are called floating ribs. The floating ribs are tipped with cartilage, for the better protection of the soft parts. The verte- bral extremity of the rib is called the head of the rib. The true ribs increase in length from above downward ; the false ribs, in the same direction, decrease in length. The first and last ribs articulate with the bodies, respectively, of the first and last dorsal vertebrae. The other ribs usually articulate each with two bodies of the dorsal vertebrae. The breadth of the ribs and the width of the intercostal spaces increase steadily, from first to last. The ribs are supported behind by the transverse processes of the vertebrae which lie behind them. The angle of the rib is the part where the bone bends more sharply, to form the side of the chest. It is farther from the head of the bone as the number of the rib increases. The upper and lower borders of the ribs give attachment to the intercostal muscles. The part of the rib between the head and tubercle — about three centimeters, or a little more than an inch in length'—is called the neck. The floating ribs (the two lower) have no neck, or tubercle. In the first rib the tubercle and angle are blended together. The word “costa” signifies a keeper, or guardian; and the ribs are the guardians of the organs of the chest. The costal cartilages are twelve in number on each side, but the last two are free, not being connected with the sternum. These cartilages in the fresh state are easily cut with a sharp knife, but when dried are almost as hard as steel. They increase in length from the first to the seventh, and then diminish, like the ribs. THE STERNUM. The sternum (solid) is the breast-bone. It is flat, broad above, and terminates below by a pointed cartilage — the xiphoid (sword- like), or ensiform (sword-form) cartilage. In the adult the sternum is composed of the manubrium (handle), the gladiolus (little sword), and the ensiform cartilage, as mentioned above. The latter is also called the ensiform appendix. It is generally cartilaginous till late in life. The manubrium is the upper part of the sternum. It articulates with the sternal end of the clavicle and with the first costal cartilage. The gladiolus, situated between the manubrium and the ensiform appendix, consists in youth of four pieces, which become united suc- cessively to the lower piece, and later in life to the manubrium. The gladiolus is sometimes perforated by a foramen — the sternal foramen. The ensiform, or xiphoid appendix is the tip, or point of the sternum. It may be broad, pointed, or forked. It is often deflected to one side. 80 OSTEOLOGY. The ensiform appendix gives attachment to the linea alba (white line), and to some fibers of the rectus abdominis (straight of the abdomen) muscle. The linea alba is formed by the flattened tendons (aponeu- roses) of the abdominal muscles. Fig. 48. THE STERNUM REDUCED IN SIZE. The sternum, costal cartilages, ribs, and dorsal vertebrae, together, form the walls of the chest, or thorax. The cavity of the thorax con- tains, in brief, the heart and lungs; but it contains, besides these, nu- merous blood-vessels, nerves, air-tubes, and other parts. Among these may be mentioned the pulmonary artery and veins, the internal mam- mary artery, the bronchial tubes and bronchial vessels (arteries and veins), the arch of the aorta, the azygos veins, the superior vena cava, the pericardium (heart-case), and portions of the thoracic duct, tra- chea (windpipe), and oesophagus ; and, in early life, the thymus body. OSTEOLOGY. 81 THE UPPER EXTREMITY. The upper extremity on either side of the body includes the shoulder, arm, forearm, and hand; and is connected to the trunk by muscles and ligaments. It has but one point of attachment to the skeleton, and that is the sterno-clavicular (sternum with the clavicle) articulation in front of the chest. The interclavicular (between the clavicles) ligament binds the two clavicles together at their sternal ends. THE CLAVICLE (Collar-bone). The clavicle (little key) and scapula (shoulder-blade), together, form the shoulder. The clavicle extends from the upper border of the sternum (breast-bone) to the acromion (“height” — it being the Fig. 49. LEFT CLAVICLE ANTERIOR SURFACE. highest point of the shoulder) process of the scapula. The extremi- ties of the clavicle are designated as the inner, or sternal end, and the outer, or acromial end. The sternal end is triangular in form; the middle portion of the bone round, or nearly so; and the outer end flattened from above, downward. The clavicle gives attachment Fig. 50. LEFT CLAVICLE INFERIOR SURFACE. 82 OSTEOLOGY. to seven muscles. It begins to ossify early in embryonic life (about the sixth or seventh week), and sooner than any other bone in the body; but its epiphysis at the sternal end does not join the shaft till about the twenty-fifth year of life. The clavicle stays the shoulder, and protects the nerves and vessels that supply the upper extremity. THE SCAPULA. The scapula (shoulder-blade) forms the back part of the shoulder. It glides over the third, fourth, fifth, and sixth ribs between the point of the shoulder and the spinous processes of the corresponding dorsal vertebrae. It is a flat, triangular bone with two surfaces, three borders, and three angles. Its two surfaces are the anterior, or inner, and the posterior, or outer. The anterior surface is next to the ribs, and is- sometimes called the venter (belly) of the scapula. The posterior, or outer surface is next to the skin, and is often called the dorsum (back) of the scapula. The three borders are the upper (superior), the internal, or vertebral (because it lies next to the vetebras), and the external, or axillary (because it lies beneath the axilla — arm-pit). The vertebral (also called the posterior) border is the base of the scapula, while the shoulder-joint forms the apex of the triangle, or the outer (external) angle of the scapula. The other two angles — the upper (superior) and lower (inferior) — form the upper and lower extremities of the internal, or vertebral, border. The outer angle at the shoulder-joint is also called the head of the scapula. The glenoid (glen-like) cavity forms the outer part of the head of the scapula. The back (dorsum) of the scapula is divided by a very prominent ridge (the spine, or spinous process of the scapula) into two very unequal por- tions, which take the name of fossae (cavities), although the lower fossa (the infra-spinous fossa — or fossa below the spine) is convex at its middle part. The portion above the spine is called the supra-spinous (above the spine) fossa. The muscles which occupy these fossae are named from their position, respectively, supra-spinatus and infra-spina- tus (above and below the spine). The spine of the scapula terminates, externally, in the acromion (highest point) process, which projects about three centimeters (an inch or more) beyond the shoulder-joint, above and behind, and articulates with the outer (or acromial) end of the clavicle. The anterior surface, or venter of the scapula, forms one broad concave surface — the subscapular (under the scapula) fossa. This fossa is occupied by the subscapularis muscle, which lies between the scapula and the ribs. OSTEOLOGY. 83 Fig. 51. LEFT SCAPULA — ANTERIOR SURFACE, OR VENTER. The head of the scapula, situated at the outer angle, is the thickest part of the bone and articulates with the humerus to form the shoulder- joint. The “ neck ” joins the head to the main portion of the bone. The constricted portion, called the neck, is best observed upon the posterior surface. From the upper part of the head and neck arises a 84 OSTEOLOGY. thick, curved process of bone — the coracoid (raven-like ; so named by Galen, from its resemblance to the beak of a raven) process. This process extends forward and outward beyond the joint of the shoul- der, protecting it in front and above in like manner as the acromion process does above and behind. The coracoid process gives attach- ment to three muscles and several ligaments. Of the muscles, one (the “ Coraco-brachialis,”— brachium, signifying arm—) extends to the middle of the humerus (bone of the arm); another (the short head of the biceps brachialis, — one of the two upper tendons of this muscle) extends to the radius (one of the bones of the forearm), just below the elbow; and the third (the “pectoralis minor” — small breast-muscle), extends to the third, fourth, and fifth ribs upon the breast, and lies beneath the pectoralis major (greater breast-muscle). On the upper border of the scapula, near the base of the coracoid process, is a semi-circular notch,— the supra-scapular (above the scapula) notch, for the passage of the supra-scapular nerve. The notch is converted into a foramen by a transverse ligament, or the foramen may be in some instances completely osseous (formed of bone). The nerve is derived from the cervical nerves, and supplies the spinatus (supra-spinatus and infra-spinatus) muscles with motor stim- ulus. The scapula gives attachment to seventeen or eighteen muscles, the latissimus dorsi sometimes forming the eighteenth. We have already mentioned six; the others are the teres, major and minor (round, greater and less), which extend from the axillary border to the upper part of the humerus; the trapezius (named from its form — a quadrilateral having no two sides parallel), extending from the spine of the scapula to the occipital bone, and thence downward along the median line of the body to the last dorsal vertebra; the deltoid (delta-like — triangular, like the Greek letter J), which extends from the spine, and acromion process of the scapula, and outer third of the clavicle to the outer surface of the humerus, near its middle part; the omo-hyoid (shoulder and hyoid bone), from the upper border of the scapula to the hyoid bone ; the triceps cubiti (three-headed of the ulna), from beneath the head of the scapula, and humerus to the olecranon (head of the elbow) process of the ulna ; the rhomboid, major and minor (form of a rhombus, greater and less), from the vertebral border of the scapula to the spinous processes of the last cervical, and four upper dorsal vertebrae, the lesser muscle lying above the other, and parallel with it; the serratus magnus (“great saw-like,” on account of its saw-teeth appearance where it joins the ribs at the side of the body), which extends from the posterior, or vertebral border of OSTEOLOGY. 85 Fig. 52. LEFT SCAPULA DORSUM, OR POSTERIOR SURFACE. the scapula to the outer surface of the first eight ribs on the side of the body, passing in front of the scapula and between the subscap- ularis muscle and the ribs ; the platysma (broad), which extends from the clavicle and acromion process to the lower jaw; and, lastly, the levator anguli scapulce (lifter of the angle of the scapula), which extends from the vertebral border of the scapula, at or near the upper angle, to the three upper cervical vertebrae. 86 OSTEOLOGY. It may be observed that there are three muscles attached to the surfaces of this bone; six to the processes, including the spine; and eight to the borders. The two spinati muscles are attached to the dorsum, or outer surface, and one, the subscapular, to the venter, or inner surface; the deltoid, platysma, and trapezius to the spinous and acromion processes; the small pectoral, biceps, and coraco-brachial to the coracoid process ; the omo-hyoid to the upper border ; the triceps and two teres muscles to the axillary border; and to the vertebral border, or base, the two rhomboids, serratus magnus, and the levator anguli scapulae. THE HUMERUS. The humerus is the longest and largest bone of the upper extrem- ity, and the only bone of the arm, bearing in mind that the arm only extends to the elbow. It is also called the os brachii (bone of the arm). The principal points to be remembered are the head, anatomical, and surgical neck, greater and less tuberosities, the bicipital groove, the small, or radial head, trochlea, and the outer and inner condyles. The head is the segment (portion cut off by a plane passing through) of a sphere, but little less than a hemisphere. It articulates with the glenoid cavity of the scapula (shoulder-blade) and forms the shoulder joint. The anatomical neck connects the head with the rest of the bone, and gives attachment to the capsular ligament which invests the joint. The surgical neck is the upper portion of the shaft just below the tuberosities, where fracture occurs more frequently than at the anatomical neck, which is larger, and very short. (The shaft is the cylindrical portion of a long bone situated between the two extremi- ties.) The tuberosities are situated exteriorly, at the upper extremity of the bone, the greater being external, and the less more in front. The two tuberosities are separated from each other by the bicipital groove, which lodges the long tendon of the biceps (two-headed) muscle. The outer and inner borders of the bicipital groove are named by Gray, respectively, the anterior and posterior bicipital ridges. The greater tuberosity has at its upper and back part three facets (little faces, or flattened surfaces), which give attachment from before backward, in the order named, to the supra-spinatus, infra-spinatus, and teres minor muscles,— all of which connect this bone with the scapula (shoulder-blade). The smaller tuberosity is situated upon the inner side of the bicipi- tal groove. It gives attachment to the sub-scapularis (under the scap- Fig. 53* Fig. 54- LEFT HUMERUS POSTERIOR VIEW. LEFT HUMERUS ANTERIOR VIEW. 88 OSTEOLOGY. ula) muscle. The bicipital groove gives attachment to three muscles — the latissimus dorsi (broadest of the back), pectoralis major (greater breast), and teres major (greater round). The lower extremity of the humerus is flattened, and curved slightly forward. At its broadest part we find the inner and outer condyles, which form the prominences at the sides of the elbow. The inner condyle is much more promi- nent than the outer. The articular surface extends a little — one or two centimeters — below the condyles, and articulates with the two bones of the forearm. The outer portion articulates with the head of the radius, and is called the radial head, or smaller head of the humerus; and the inner portion articulates with the ulnar, and is called the trochlea (a pulley, or turning-point). Above the trochlea, in front, is the coronoid (Greek, “ xvpwvrjP a crow) fossa, which receives the coronoid process of the ulna during flexion of the forearm, and opposite, on the other side of the bone, is the olecranon (head of the elbow) fossa, which receives the olecranon process during exten- sion of the forearm. Twenty-five muscles are attached to the humerus — 7 to the upper end, 5 to the shaft, and 13 to the condyles (5 to the inner and 8 to the outer condyle). Those of the inner condyle, five in number, are the superficial pro- nators (from “pronus,” inclining forward, as when we turn the hand inward to look upon its back), and the flexors (benders) ; and those attached to the outer condyle, eight in number, are the superficial supi- nators (from “supinus,” lying on the back, as when the hand is turned outward, and the palm upward), and the extensors (stretchers, or straight- eners). Of the 25 muscles, 20 are attached to the upper and lower extremities, and 5 to the shaft. The 5 attached to the shaft are the deltoid, coraco-brachial (or coraco-brachialis), anterior brachial (brachialis anticus), triceps of the ulna (triceps cubiti), and subanconeus (the small of the elbow). Of those attached to the upper extremity, 3 are attached to the greater tuberosity, 3 to the bicipital groove, and 1, the subscapula (under the shoulder-blade), to the smaller tuberosity. THE ULNA. The ulna (“ o-le-ne ” in Greek and cubitus in Latin) is the longer of the two bones (ulna and radius) of the forearm. The ulna is situated on the same side as the little finger. Like all long bones, it has a shaft and two extremities. The upper extremity, where it articulates with the humerus above and radius at the side, is much larger than the lower extremity, which articulates with the radius, only, and is separated from the bones of the wrist by an intervening fibro-cartilage (fibrous tissue Fig- 55- BONES OF THE LEFT FOREARM — ANTERIOR SURFACE. 90 OSTEOLOGY. and cartilage united, making the structure dense, elastic, firm, and flex- ible). The part of the ulna that articulates with the trochlear surface of the humerus is the greater sigmoid cavity; and that articulating with the head of the radius on the outer side, is the small (lesser) sigmoid cavity of the ulna. There is also a sigmoid cavity of the radius, which articulates with the lower extremity (head) of the ulna. (Sigmoid sig- nifies resemblance to the Greek letter “Sigma,” corresponding to our “S,” and was made, when standing in the middle of a word, much like our “O,” as follows, vSp<>{ [chondroi]) of the true ribs, except the first, are united to the sternum in middle life by arthrodial joints and syno- vial membranes, and the articulations (joints) are called chondro-ster- nal. The cartilage of the first rib is united to the sternum directly, as the remaining six are also generally found in old age. The second has an interarticular ligament, and two synovial membranes like some of the joints at the head of the rib. The third has also two synovial mem- branes ; the rest, one each, making eight synovial cavities between the costal cartilages and ribs on each side of the body. The ligaments of these joints are the anterior, and posterior costo-sternal (more properly chondro-sternal), costo (or chondro) xiphoid, and the cap- sular. 7. ILIO-SACRAL ARTICULATION. The ilio-sacral (or sacro-iliac, union of the sacrum and ilium) artic- ulation has two ligaments — the anterior and posterior sacro-iliac liga- ments. 8. ISCHIO-SACRAL CONNECTION. This joint is ligamentous only, since the bones connected are not contiguous. The connection is made by means of two ligaments (the greater and less sacro-sciatic, connecting the sacrum and ischium),, which convert the sacro-sciatic notches into foramina 9. COCCYGEO-SACRAL JOINT. This joint is similar to that between the vertebrae. It has an inter- articular fibro-cartilage and two ligaments — the anterior and posterior sacro-coccygeal. io. INTER-PUBIC JOINT. This joint has an intervening fibro-cartilage and four ligaments— the anterior, posterior, superior, and inferior (or sub-pubic). ARTHROLOGY. 129 11. STERNO-CLAVICULAR JOINT. The sternum and clavicle form an arthrodial (gliding) joint; and the same is true of the clavicle at its acromial end. Both joints have an interarticular fibro-cartilage. The sterno-clavicular ligaments are Fig. 76. STERNO-CLAVICULAR ARTICULATION. the anterior and posterior sterno-clavicular, inter-clavicular (extending' across the upper border of the sternum from one clavicle to the other), and costo-clavicular (or rhomboid). The latter extends obliquely be- tween the sternal end of the clavicle, above, and the first rib below, and has the form of a rhombus (an equilateral, oblique-angled parallelogram). Fig. 77- X. Interclavicular Ligament. 2. Anterior Sterno-Clavicular Ligament. STERNOCLAVICULAR LIGAMENTS. 3. Costo-Clavicular Ligament. 4. Interarticular Fibro-Cartilage. 130 ARTHROLOGY. 12. SCAPULO-CLAVICULAR JOINT. This joint has four ligaments — upper and lower acromio-clavicular (connecting the clavicle with the acromion process of the scapula), trapezoid, and conoid, ligaments. The two latter are coraco-clavicular (connecting the clavicle with the coracoid process of the scapula). Fig. 78. THE LEFT SHOULDER JOINT. This joint has sometimes a more or less complete interarticular fibro- cartilage. There are one or two synovial membranes, depending upon the existence, or absence, of the intervening fibro-cartilage. 13. INTER-SCAPULA CONNECTIONS. This group is not properly a joint, but two ligamentous unions, connecting parts of the scapula (shoulder-blade) with each other. The coraco-acromial ligament connects the coracoid and acromion processes, ARTHROLOGY. 131 and completes the vault formed by these processes for the protection of the head of the humerus. The transverse ligament of the scapula runs across the upper border of the scapula, near the coracoid process, and converts the supra-scapular (above the scapula) notch into a foramen which transmits the supra-scapular nerve and blood-vessels. 14. HUMERO-SCAPULAR JOINT. The shoulder joint is enarthrodial (ball and socket joint), and allows the freest motion of all the numerous joints. It is protected above and in front by an arched vault, formed by two strong, bony processes (the acromion and coracoid of the scapula), and the coraco-acromial ligament connecting them. The ligaments of the shoulder joint are the capsu- lar, coraco-humeral, and glenoid. The glenoid ligament surrounds the margin of the glenoid cavity of the scapula. It deepens the cavity, and serves to protect the edges of the bone. The coraco-humeral (con- necting the coracoid process of the scapula with the humerus) ligament blends at its outer part with the upper part of the capsular ligament, which it serves to strengthen. It extends from the anatomical neck of the humerus to the coracoid process of the scapula. The capsular ligament completely encircles the joint. It is attached at one extremity to the anatomical neck of the humerus, and at the other to the circumference of the glenoid cavity, inclosing the glenoid ligament. The synovial membrane lines the inner surface of the cap- sular ligament, and is reflected upon the tendon of the biceps muscle, which passes through the joint without entering the synovial cavity. 15. HUMERO-ULNAR JOINT. The humero-ulnar articulation (elbow joint) is formed by articula- tion of the humerus with the greater sigmoid cavity of the ulna and head of the radius, although none of its ligaments are attached directly to the radius, but connect the humerus with the ulna and orbicular ligament, which latter surrounds the head of the radius, and thus binds it to the ulna. The elbow joint is ginglymoid (hinge-like). Its ligaments are the anterior, posterior, internal lateral, and external lateral. The posterior ligament connects the olecranon process with the posterior surface of the humerus; the anterior connects the ante- rior portion of the humerus and inner condyle with the orbicular liga- ment and coronoid process; the external lateral ligament connects the 132 ARTHROLOGY. Fig. 79. Fig. 8o, a. External lateral liga- ment. b. Orbicular or annular ligament. HEAD OF THE RADIUS, REMOVED FROM THE ORBICULAR LIGAMENT. LEFT ELBOW JOINT. external condyle with the orbicular ligament; and the internal lateral connects the internal condyle with the olecranon process (by the pos- terior portion of the ligament) and (by its anterior portion) to the inner margin of the coronoid process of the ulna. The synovial membrane covers the margin of the articular surface of the humerus (the trochlea surface and radial head), lines the coro- noid and olecranon depressions, is reflected over the inner surface of the ligaments, and dips down between the smaller sigmoid cavity and head of the radius. ARTHROLOGY. 133 16. RADIO-ULNAR JOINTS. The radio-ulnar articulations connect these bones (radius and ulna) at both extremities, and also the two shafts. The upper extremities are connected by the orbicular (sometimes called “annular”) ligament,which surrounds (with the aid of the smaller sigmoid cavity of the ulna) the head of the radius, and retains it in firm connection with the cavity. The two shafts are connected by two ligaments,— the oblique (or round), and “ interosseous ” membrane. The round, or oblique, is sometimes wanting. It extends obliquely downward and outward from the base of the coronoid process of the ulna to the shaft of the radius, a little below the bicipital tuberosity. The interosseous ligament is an aponeurotic membrane, connecting the external border of the ulna with the internal border of the radius. It serves, also, as a surface for the attachment of muscles. It is deficient above, adjoining the oblique ligament, and allows passage to the posterior interosseous vessels. The lower extremities of the radius and ulna are connected by the “radio-ulnar” ligaments (anterior and posterior). A triangular fibro-cartilage, situated between the end of the ulna and the wrist-bones, separates this joint (the radio-ulnar near the wrist) and its synovial membrane from the wrist-joint; but sometimes the two joints (wrist and radio-ulnar) communicate through an opening in the fibro-cartilage. 17. CARPAL JOINT. The wrist (carpal) joint has four ligaments — anterior, posterior, and two (internal and external) lateral. The synovial membrane lines the under (or carpal) surface of the triangular fibro-cartilage, and is reflected on the inner surface of the ligaments that surround the joint. The wrist-joint is covered by the tendons of the muscles that run from the forearm to the hand. The flexors are in front. 18. INTER-CARPAL JOINTS. The pisiform bone is joined to the cuneiform by a separate arthro- dial (gliding) joint. The cuneiform, semilunar, and scaphoid (bones in the radial or upper row) are joined by two dorsal, two palmar, and two interosseous ligaments. The four bones of the second row are also joined by dorsal, palmar, and interosseous ligaments ; and the two rows are joined together by ligaments similar to those of the elbow and wrist — anterior, posterior, and two lateral (internal and external). Fig. 81. LIGAMENTS OF THE WRIST AND PALM — POSTERIOR VIEW. Fig. 82. LIGAMENTS OF THE WRIST AND PALM — ANTERIOR VIEW. ARTHROLOGY. 135 19. CARPO-METACARPAL JOINTS. The joints between the carpal and metacarpal bones are arthrodial (gliding) joints. The first metacarpal bone is united to the trapezium by a capsular ligament and separate synovial membrane ; the other metacarpal bones are united to the carpal bones by the aid of dorsal, Fig. 83. SYNOVIAL MEMBRANES OF THE WRIST. palmar, and interosseous ligaments. The interosseous ligaments con- nect the third and fourth metacarpal bones to the os magnum and unciform. There is one synovial membrane for all the carpo-metacar- pal joints, except that of the trapezium with the thumb. The metacarpal bones, all except the first, articulate with each other at both extremities. The carpal (wrist) extremities are bound together by dorsal, palmar, and interosseous ligaments. The interos- seous pass between the bones ; the dorsal are directed across the back of the hand, and the palmar across the palm. The digital (next the fingers) extremities are connected by a fibrous band,— the transverse ligament,— which passes across them. 20. INTER-METACARPAL ARTICULATIONS. 136 ARTHROLOGY. 21. PHALANGEAL. These joints have been already described. 22. INTER-METATARSAL JOINTS. This group so closely resembles the 20th as to require no separate description. The only point of difference is the transverse ligament. It differs from the transverse ligament of the hand, in connecting the first with the other metatarsal bones. 23. TARSO-METATARSAL JOINTS. This group has dorsal, plantar, and interosseous ligaments, and synovial membranes that extend between the bases of the metatarsal bones. 24. INTER-TARSAL JOINTS. The seven bones of the ankle (tarsus) are connected by nine- teen different ligaments and four synovial membranes. The os calcis (heel-bone) is bound firmly to the astragalus, which rests upon Fig. 84. RIGHT ANKLE JOINT — OUTER SIDE. ARTHROLOGY. 137 its anterior part by three ligaments — one interosseous, and two cal- caneo-astragaloid (posterior and external). The interosseous ligament fills the groove found on the contiguous surfaces of these two bones. The os calcis (or calcaneum) is bound to the scaphoid by two liga- ments (superior, and inferior calcaneo-scaphoid) ; and the same bone is bound to the cuboid by four ligaments (the long, short, superior, and internal calcaneo-cuboid). The long and short calcaneo-cuboid liga- Fig. 85. INTEROSSEOUS LIGAMENTS OF THE CUNEIFORM BONES. ments are plantar (on the sole of the foot), the others dorsal (on the upper part). The long calcaneo-cuboid ‘ligament extends from the under surface of the calcaneum (heel-bone) along the under surface of the cuboid bone to the bases of the metatarsal bones. The second row of tarsal bones are bound together by dorsal, plantar, and interos- seous ligaments. Fig. 86. RIGHT ANKLE JOINT — INNER SIDE. 138 ARTHROLOGY. 25. TARSAL JOINT (Ankle). The ankle is a ginglymoid (hinge-like) joint. It is formed chiefly by the articulation of the tibia with the astragalus ; but the lower end of the fibula rests against the outer side of the astragalus, and forms the external malleolus. The ligaments of the ankle-joint are the ante- Fig. 87. LIGAMENTS ON THE PLANTAR SURFACE (BOTTOM) OF THE FOOT. rior and two lateral (internal and external), the posterior ligament being supplied by the transverse ligament of the tibia and fibula. The internal lateral ligament, on account of its shape, is also called the deltoid (delta-like ; i. e., triangular). It connects the internal malleolus with three bones (scaphoid, os calcis, and astragalus). The external lateral ligament of the ankle consists of three distinct parts, called ARTHROLOGY. 139 Fig. 88. SYNOVIAL MEMBRANES OF THE ANKLE. fasciculi (little bands). The anterior fasciculus runs from the external malleolus forward to the astragalus ; the middle fasciculus runs down- ward to the os calcis; and the posterior fasciculus backward to the astragalus. 26. TIBIO-FIBULAR ARTICULATION. The tibia articulates with the fibula at both extremities. The superior articulation is an arthrodial joint, and its synovial membrane is sometimes continuous with that of the knee. The superior articula- tion has two ligaments (anterior and posterior), and the inferior artic- ulation four ligaments. The four lower ligaments are the inferior interosseous, the transverse, an anterior and a posterior ligament. Besides the upper and lower articulations, the shafts of the tibia and fibula are connected by an interosseous membrane, which extends between the contiguous borders of the shafts, and separates the muscles in front from those on the back of the leg. It is perforated, for the passage of blood-vessels. 27. TIBIO-FEMORAL JOINT. The knee-joint (tibio-femoral articulation) is a ginglymoid (hinge- like) joint. It has ten ligaments (five external and five internal liga- ments). Some authors give more. The internal ligaments occupy the interior of the joint. The ligamentum patellae (ligament of the patella) is one of the external ligaments of the knee. It is a continuation of the tendon of the quadriceps (or triceps) extensor muscle, and is some- times called the anterior ligament of the knee, since it supplies the 140 ARTHROLOGY. place of an anterior ligament. Two synovial bursae are connected with this ligament and the patella; one is interposed between the patella and the skin, and the other beneath the ligament, and separating it from the tibia. The remaining external ligaments are the posterior (sometimes called the ligament of Winslow), the capsular, and the two lateral (in- ternal and external). The posterior covers the whole of the back part of the joint, and forms part of the floor of the popliteal space, and upon Fig. 89. RIGHT KNEE-JOINT — POSTERIOR VIEW. it rests the popliteal artery. The internal lateral ligament connects the inner tuberosities of the tibia and femur. The external lateral ligament connects the outer tuberosity of the femur with the head and styloid process of the fibula. The capsular ligament completes the investment of the joint. The synovial membrane of the knee is the largest in the body. It forms a large cul-de-sac (blind alley), which extends upward, beneath the tendon of the extensor muscles, four or five centimeters (one or two inches) above the articular surface of the femur, and has ARTHROLOGY. 141 several other processes. Two or three folds of the synovial membrane have been by some authors described as ligaments, and named liga- mentum mucosum (mucous ligament), and ligamenta alaria (winged Fig. 90. RIGHT KNEE-JOINT—ANTERIOR VIEW. ligaments). Some short fibrous bands which connect the semilunar cartilages with the head of the tibia are by some authors called coronary ligaments. The internal ligaments of the knee include two crucial Fig. 91. Fig. 92. CRUCIAL LIGAMENTS. HEAD OP TIBIA AND SEMILUNAR CARTILAGES. 142 ARTHROLOGY. (external and internal, or anterior and posterior), two semilunar fibro- cartilages (internal and external), and a transverse ligament. The anterior crucial ligament is attached to the anterior surface of the tibia, in front of the spine of the tibia, and the posterior crucial to the pos- terior surface of the tibia behind the spine. The anterior passes to the external condyle (inner and back part), while the posterior crucial passes to the inner (or internal) condyle (outer and fore part), so that the two cross each other in the region of the spine of the tibia. The semi- lunar fibro-cartilages are interposed between the condyles and the inner and outer articular surfaces of the tibia. The transverse ligament con- nects the anterior margins of the two semilunar fibro-cartilages. 28. COXO-FEMORAL (HIP) JOINT. The hip-joint (coxo-femoral) is enarthrodial (ball and socket), and has five ligaments; two are circumferential (around the circum- Fig- 93- LEFT HIP-JOINT, LAID OPEN. ference of the cotyloid cavity), and three are connecting ligaments. The five ligaments of the hip are the capsular, the ilio-femoral, or “Y” ligament, the cotyloid, the transverse, and the ligamentum ARTHROLOGY. 143 teres (round, or polished ligament). The capsular ligament extends from the outer margin of the acetabulum (cotyloid cavity) to the in- tertrochanteric lines of the femur, covering its head and neck. The ilio-femoral extends from the anterior inferior spine of the ilium to the anterior intertrochanteric line, where it blends with the capsular liga- ment. The cotyloid is attached to the margin of the cotyloid cavity (acetabulum), and serves to deepen it, and protect the margin of the bone. The transverse extends across the cotyloid notch, and forms it into a foramen for the nutrient vessels to the joint. The ligamentum teres extends from the bottom of the cotyloid cavity to the depression found upon the head of the femur, a little below the center of its artic- ulating surface. The synovial membrane of the hip-joint is quite extensive. It com- mences at the margin of the cartilaginous surface of the head of the femur, covers all that portion of the neck invested by the capsular lig- ament, is reflected upon the internal surface of the capsular ligament, and forms a tubular sheath around the ligamentum teres. Sometimes it communicates with a bursa beneath the tendons of the psoas and iliac muscles. Articulation and joint are not exactly synonymous, as used in anatomy, although often used interchangeably. Bones are said to articulate (form a small joint) whenever they touch each other, but a joint may be composed of two, three, or four bones. The hip and shoulder joints have two bones each; the elbow, knee, and ankle three each ; and the wrist-joint, four bones. The body has 195 artic- ulations, but not so many joints. A joint may include several articula- tions (small joints). MYOLOGY [Muscle-Study]. The muscles (movers) are the active organs of motion, acting under the influence of the nerves. They are formed of bundles of fibers endowed with the property of contractility. They constitute the lean meat of the body, and are so packed and arranged as to give symmetry of form, rapidity and grace of motion. There are two kinds of muscular tissue,— the striped, or striated (furrowed), and the unstriated. The muscular tissue marked with striae (furrows), forms, with one exception (that of the heart), the voluntary muscles; and the unstriated muscular tissue is always found composing involuntary muscles. The heart is composed largely of striated fibers, and yet is not generally under the control of the will. The voluntary muscles are governed by the cerebro-spinal (brain and spinal) system of nerves ; the involuntary, by the sympathetic system. The latter carry on the important processes of respiration, circulation, and nutrition, and are called muscles of organic life. The muscular fiber of organic life forms the muscular coat of the alimentary canal below the middle of the oesophagus; is found in the posterior wall of the trachea (windpipe); in the bronchi (bronchial tubes) ; in the ure- ters and bladder; in the coats of the arteries, veins, and lymphatic ves- sels ; in the iris, the ciliary muscle of the eye ; and in many other parts. Nearly all the muscles that have received names are voluntary muscles, and are governed by the nerves of the cerebro-spinal sys- tem. These muscles are all symmetrical with reference to the median plane of the body, and with the exception of four single muscles in the male, and five in the female, are in pairs. The voluntary muscles are, for the most part, attached to the bones, or periosteum (membrane around the bone), and are sometimes called skeletal muscles. The bundles of fibers which compose a voluntary muscle are them- selves composed of bundles of filaments, or fibrils (small fibers), and each filament is inclosed in a delicate sheath, called the sarcolemma (flesh- coat). The whole muscle is invested with a sheath, called the perimys- ium (around the muscle). MYOLOGY. 145 The elementary particles which make up the muscular filament have been called sarcous elements (flesh elements). Each sarcous element is probably a nucleated cell. The perimysium (sheath around the muscle) generally takes the name of fascia (band or bandage). The fasciae (“bandages”—plural of fascia) are divided into superficial and deep fasciae. The superficial fascia is found immediately beneath the skin, over nearly the entire surface of the body, and connects the skin with the deep fasciae. The deep fascia is also called aponeurotic fascia, or aponeurosis (“from, or out of, nerve or tendon.” The ancients called every white part “ veupov,” or nerve). An aponeurosis is a tendinous expansion, or a firm, white, fibrous membrane, and serves to connect a muscle with a bone, when it is called an aponeurosis of insertion ; and to connect one part of a muscle with another, as a central tendon, or as a membranous covering for a muscle, when it is called an aponeurosis of investment. An aponeurosis differs from a tendon only in being flat, or membranous, while the tendon is generally round, or slightly flattened. The tendons connect the muscles to the bones, and thus transmit their motion to greater or less distances. The end of the muscle at- tached to the more fixed part is usually considered the “origin,” and the other end the “insertion” of the muscle. In the limbs the fasciae invest the entire limb, and also give off septa (partitions), which separate the various muscles, and are attached to the periosteum. The muscles are numerous, but vary somewhat in number according to different authors, some regarding as separate muscles what others regard only as parts, or portions. Gray gives 245 names of muscles, and these include only four single muscles, the rest being pairs and sets, making, altogether, 682 separate, or individual muscles. Of these, only 680 belong to either sex separately. Taking Gray as a basis, we shall omit the following pairs; viz., six small and unimportant muscles of the auricle (external ear), which ex- tend from one part of the auricle to another; three names applied by Albinus to parts of the hyo-glossus ; one, which is a part of the spiral lamina of the internal ear; one of the middle ear, which is often re- garded as a ligament; one of the thyroid gland, which is not constant; one of the prostate gland, because it is a part of the sphincter ani, and two, which are parts of the splenius, and thus reduce the entire number to 652 muscles, with 230 distinct names. The four single muscles of the male are the diaphragm, sphincter ani (the internal sphincter), arytenoid, and orbicularis oris, and to these are added in the female the sphincter vaginae. 146 MYOLOGY. The pairs include, among others, 109 pairs which are described in eleven different sets. The eleven sets are the supra-spinales (above the spinous processes of the vertebrae), 6 pairs; the rotatores spince (rotators of the spine), 11 pairs; lumbricales (earth-worms), 8 pairs; levatores costarum (lifters of the ribs), 12 pairs; intertransverse (between the transverse processes), 23 pairs; interspinales (between the spinous processes), 13 pairs; palmar interossei (between the bones of the palm), 3 pairs; plantar interossei (between bones of the sole of foot), 3 pairs ; dorsal interossei (between bones of back of hand and foot), 8 pairs; internal intercostal (between the ribs), 11 pairs; and the external intercostal, 11 pairs. Besides these eleven sets, there are, by name, 8 pairs of levators (lifters), 13 extensors, 13 flexors, 11 straight (“ rectus,” plural recti), 6 oblique (obliquus), 5 adductors (“leading toward,” or drawing toward the axis, or median plane of the body), 4 abductors (“leading from”), 4 transverse (running across), 4 tensors, 3 each of the gluteal, erectors, depressors, compressors, constrictors, peroneal, sphincters (contractors), saw-like (“serrati,” plural of serratus), and scalene (a triangle with unequal sides), and 2 each of the gemelli (plural of gem- ellus, “ twin ”), dilators, obturators, biceps, quadrati (plural of quad- ratus), rhomboid (or rhomboideus), spinales (plural of spinalis), zygo- matic, vasti (plural of vastus), palmares (plural of palmaris), pectoral, pronators, supinators, teres, tibiales (plural of tibialis), crico-arytenoid, psoas, pterygoid, and pyramidal. The muscles vary greatly in form and size, and take their names from their use, shape, dimensions, direction, attachments, etc. Of the 230 names of sets, pairs and single, 42 are muscles of the cranium and face, 52 of the lower extremities, and 46 each in the neck, trunk, and uppep extremities. The lumbricales and dorsal inter- ossei are situated in both the hands and feet, and are enumerated twice. DIFFERENT NAMES OF THE SAME MUSCLE. The “abductor indicis” of some authors is the “first dorsal inter- osseous” of the hand. The “triceps extensor cruris” of authors is the collective name of three muscles — the two vasti and crureus. The “ quadriceps extensor ” includes the same three muscles as the triceps, together with the rectus femoris. The depressor alae nasi is sometimes called the myrtiformis (form of a myrtle leaf), and, by some authors, depressor labii superioris alaeque nasi. The depressor anguli oris is also called the triangularis menti (triangular of the chin). The MYOLOGY. 147 depressor labii inferioris is also called quadratus menti (square of the chin). The levator labii inferioris is also called levator menti. _ The opponens minimi digiti and opponens pollicis sometimes have in place of the word “opponens” the three words “flexor ossis met- acarpi,” making of the first, flexor ossis metacarpi minimi digiti. Fig. 94. MUSCLES OF THE HEAD, FACE, AND NECK, The palato-glossus is the constrictor isthmi faucium. The sterno- mastoid is the sterno-cleido-mastoid. The “triceps” is the triceps cubiti, or triceps extensor cubiti. 148 MYOLOGY. MUSCLES OF THE CRANIUM AND FACE (Twelve Groups). The muscles of the cranium and face form twelve groups, named from the region which they occupy: — First.— Epicranial (upon the cranium), 1 muscle, the occipito-frontalis. Fig- 95- x. Risorius. 14. Buccinator. 2. Orbicularis Oris. 15. Occipito-frontalis. 3. Depressor Anguli Oris. j6. Masseter. 4. Depressor Labii Inferioris. 17. Sterno-mastoid. 5. Levator Menti. 18. Trapezius. 6. Orbicularis Palpebrarum. 19. Splenius Capitis. 7. Zygomaticus Major. 20. Digastric. 8. Zygomaticus Minor. ax. Levator Proprius Alas Nasi Anterior, 9. Pyramidalis Nasi, or, Dilatator Naris Anterior. 10. Compressor Naris. 22. Levator Proprius Alas Nasi Posterior, n. Levator Labii Superioris et Alas Nasi. or, Dilatator Naris Posterior. 12. Levator Labii Superioris. 23. Platysma Myoides. 13. Levator Anguli Oris. 24. Depressor Alae Nasi. Second.—Auricular (ear), 3 muscles. These are the attollens aurem (raising the ear), attrahens aurem (drawing the ear forward), and retrahens aurem (drawing the ear backward). MYOLOGY. 149 Third.— Tympanic (middle ear), 3 muscles: laxator tympani (loosener of the drum), tensor tympani (tightener of the drum), and stape- * dius (moves the stapes — “stirrup”). Fourth.—Palpebral (eyelid), 3 muscles: orbicularis palpebrarum (round of the eyelids), corrugator supercilii (wrinkles the eye- brows), and tensor tarsi (compresses the tarsal cartilages). Fifth.—Intra-ocular (within the eye), 1 muscle, the ciliary. This muscle adjusts the eye to different distances. Sixth.— Orbital (around the eyeball), 7 muscles: levator palpebrae (lifts the upper lid); rectus superior (turns the eye upward) ; rectus in- ferior (turns the eye downward); rectus internus (turns the eye inward) ; rectus externus (turns the eye outward); obliquus supe- rior (rotates the eyeball) ; obliquus inferior (rotates the eyeball). Seventh.— Nasal (nose), 7 muscles: compressor naris (compresses the nose) ; compressor narium minor (small compressor of the nostrils) ; depressor alae nasi (constricts the nares); dilator naris anterior, dilator naris posterior (enlarge the aperture of the nose) ; levator labii superioris alaeque nasi (lifter of the upper lip and wing of the nose) ; pyramidalis nasi (draws down the eyebrow). Eighth.— Superior maxillary (upper jaw), 5 muscles : levator labii supe- rioris (lifter of upper lip) ; levator anguli oris (lifter of the angle of the mouth) ; zygomatic major, zygomatic minor (raise the upper lip, and draw it outward, as in laughing) ; naso-labialis (connecting the upper lip and septum of the nose). Ninth.— Inferior maxillary (lower jaw), 3 muscles: levator labii in- ferioris (lifter of the lower lip), depressor labii inferioris (depressor of lower lip), depressor anguli oris (depressor of angle of the mouth). Tenth.— Intermaxillary (between the jaws), 5 muscles: buccinator (trumpeter — compresses the cheeks), risorius (laughing muscle — aids the zygomatic), orbicularis oris (closes the lips or mouth), accessorius orbicularis superioris (aids the orbicular), anomalus (irregular — between the nose and cheek). Eleventh.— Temporo-maxillary (connecting the lower jaw and tem- poral bone), 2 muscles: masseter (masticator — raises the lower jaw), temporal (raises the lower jaw). Twelfth.— Pterygo-maxillary (connecting the pterygoid processes with the lower jaw), 2 muscles: pterygoid externus, pterygoid internus (raise the lower jaw and triturate the food). 150 MYOLOGY. MUSCLES OF THE NECK (Nine Groups). First.— Superficial muscles, 2 pairs: platysma myoid (broad, muscle- like), sterno-cleido-mastoid (named from its attachment to the sternum, clavicle, and mastoid process). Second.— Infra-hyoid (below hyoid bone), 4 pairs: sterno-hyoid (con- nects the sternum and hyoid bone) ; sterno-thyroid (connects the sternum and thyroid cartilage); omo-hyoid (shoulder and hyoid bone) ; thyro-hyoid (thyroid cartilage and hyoid bone.) Third. — Supra-hyoid (above the hyoid bone), 6 pairs. Digastric (“two bellies,” the middle, fleshy part of a muscle is called its belly); genio-hyoid (chin and hyoid bone); genio-hyo-glossus (chin, hyoid bone, and tongue); hyo-glossus (hyoid bone and tongue); lingualis (forms the under part of the tongue); mylo- hyoid (lower jaw and hyoid bone). Fourth.—Submaxillary, 3 pairs : stylo-hyoid (styloid process and hyoid bone) ; stylo-glossus (styloid process and tongue) ; stylo-pharyngeus (styloid process and pharynx). Fifth.— Prevertebral (before the vertebrae), 7 pairs: longus colli (long of the neck) ; rectus capitis anticus major, rectus capitis anticus minor (these antagonize the post-vertebral muscles) ; rectus capitis lateralis (extends from the transverse process of the atlas to the jugular process of the occiput) ; scalenus anticus, scalenus medius, scalenus posticus (raise the first and second ribs, or flex the neck sideways. The scalene are all attached to the transverse processes of the cervical vertebrae, and extend to the first and second ribs). Sixth.— Post-vertebral (behind the vertebrae, 8 pairs : splenius capitis et colli (splenius of the head and neck), or, simply, splenius; trachelo-mastoid (lower cervical and upper dorsal vertebrae with the mastoid process); complexus (four of the lower cervical and upper dorsal vertebrae with the occipital bone); biventer cervicis (two-bellied of the neck,— blends with the complexus); obliquus capitis superior (superior oblique of the head) ; obliquus capitis in- ferior (inferior oblique of the head) ; rectus capitis posticus major, rectus capitis posticus rhinor (larger and smaller straight muscles of the head behind the spine). Seventh.— Palatic (of the palate) 5 pairs : tensor palati (stretcher of the soft palate) ; levator palati (lifter of the palate) ; palato-glossus, or constrictor isthmi faucium (soft palate and side of the tongue); palato pharyngeus (soft palate with the throat and posterior border of the thyroid cartilage); azygos uvulae (is not single, as its name implies. It extends from the palate bone to the uvula). MYOLOGY. 151 Eighth.— Pharyngeal (of the pharynx), 3 pairs : superior constrictor, middle constrictor, and inferior constrictor (these muscles are the chief agents of deglution, carrying the contents of the pharynx into the oesophagus). Fig. 96. MUSCLES OF THE PHARYNX—EXTERNAL VIEW. Ninth.— Laryngeal (of the larynx), 7 pairs and 1 single: arytenoid (“ladle-shaped,” a single muscle, situated between the two aryten- oid cartilages, and narrows the glottis); aryteno-epiglottideus superior (constricts the upper aperture of the larynx) ; aryteno-epi- glottideus inferior (compresses the sack of the larynx) ; crico-thyroid (elongates and tightens the voca. cords) ; crico-arytenoid posticus (rotates the arytenoid cartilages and opens the glottis); crico- arytenoid lateralis (rotates the cartilages and closes the glottis) ; thyro-arytenoid (shortens and relaxes the vocal cords) ; and thyro- epiglottideus (compresses the sack of the glottis). 152 MYOLOGY. MUSCLES OF THE TRUNK (Forty-six Pairs and Sets, in Four Groups). First.— Abdominal, 7 pairs in the male, 6 in the female: rectus abdominis (straight of the abdomen) ; pyramidalis (form of one side of a pyramid, triangular) ; obliquus externus (external oblique); obliquus internus (internal oblique) ; cremaster (found in the male only, and is really only some of the lower fibers of the internal oblique); transversalis abdominis (transverse of abdomen); and quadratus lumborum (square of the loins). Second.— Thoracic (of the thorax — chest), 6 pairs, sets, or single : in- tercostal, external, 11 pairs ; intercostal, internal, 11 pairs (between the ribs) ; infracostal (within the ribs — not constant); levatores costarum (lifters of the ribs), 12 pairs ; triangularis sterni (triangu- lar of the sternum, draws down the costal cartilages of the second, third, fourth, and fifth ribs) ; and the diaphragm (divider), separates the cavities of the chest and abdomen. Fig. 97. A TRANSVERSE SECTION OF THE ABDOMEN IN THE LUMBAR REGION. Third.— Dorsal (of the back), 23 pairs and sets. These muscles are in five layers. First layer.— Trapezius (named from its form: the two muscles taken together forming a quadrilateral, but one alone is triangu- lar) ; and latissimus dorsi (broadest of the back). MYOLOGY. 153 Second layer.— Levator anguli scapulae (lifter of the angle of the scapula); rhomboid major, and rhomboid minor (these two muscles, side by side, form one oblique-angled parallelogram [rhombus], and extend obliquely between the spine and posterior border of the scapula). Third layer.— Serratus posticus superior and serratus posticus inferior (‘‘saw-like,” and placed at the upper and lower part of the back). Fourth layer.—Cervicalis ascendensand transversalis colli (extend into the neck) ; accessorius ad sacro-lumbalem (aid to the sacro-lum- balis); spinalis colli (or spinalis cervicis) and spinalis dorsi (connect the spinous processes of the neck and back); longissimus dorsi (longest of the back); sacro-lumbalis (this and the preced- ing are parts of the erector spinae) ; and erector spinae (in the loins). The erector spinae extends from the sacrum to the lower rib, where it divides into the two preceding. Fig. 98. *■ Aorta passing be- tween the crura, a. Opening for oeso- phagus. » 3- Opening for vena cava. 4. Quadralus liflhbo- rum. 5. Psoas magnus. The dark arches above the quad- ratus and psoas are the ‘ arcuate ligaments.’ THE DIAPHRAGM. Fifth layer.—Semi-spinalis dorsi; semi-spinalis colli; multifidus spinae; rotatores spinas, 11 pairs ; supra spinales, 6 pairs ; inter-spinales, usually 13 pairs; extensor coccygis; and intertransversales, 23 pairs. (These muscles all connect various parts of the verte- brae with each other, and may in general terms be called spinal muscles). Fourth.— Perineal (of the perineum), 7 pairs, 9 in both sexes. Erec- tor penis (in the female, erector clitoridis instead); accelerator urinae (absent in the female, but another is added — sphincter vaginae) ; transversus perinei (transverse of the perineum) ; com- pressor urethrae (surrounds and compresses the membranous portion of the urethra); sphincter ani (external) ; levator ani, and coc- cygeus (in the floor of the pelvis). 154 MYOLOGY. The number of muscles in the perineum is increased to eight (ten if both sexes be considered), if we reckon the internal sphincter ani. It is an aggregation of the circular fibers of the rectum. MUSCLES OF THE UPPER EXTREMITY (Forty-six Pairs and Sets, in Seven Groups.) First.— Brachio-thoracic muscles (connecting the arm and trunk), 4 pairs: pectoralis major, pectoralis minor (breast muscles — greater and less); subclavius (under the clavicle: connects the clavicle with the cartilage of the first rib); serratus magnus (great saw- tooth, or saw-like muscle: extends from the posterior border of the scapula to eight upper ribs at the side). The serratus magnus rests upon the ribs and intercostal muscles, and is covered in front by the pectoral muscles, and behind by the sub- scapularis, which separates it from the scapula, or shoulder blade; so that we have two muscles lying between the shoulder blade and ribs. Second.— Omo-brachial (connecting shoulder and arm), 7 pairs : del- toid (delta-like,— the-delta A, is the fourth letter of the Greek alphabet, and is triangular in form); supraspinatus (“above the spine” of the scapula) ; infraspinatus (“below the spine” of the scapula) ; teres major, teres minor (“ round, or smooth,” greater and less) ; subscapularis (under the scapula) ; coraco-brachialis (coracoid process to the humerus). Third.— Brachial (situated on the arm), 4 pairs : biceps flexor cubiti (two-headed flexor of the forearm); brachialis anticus (anterior brachial); triceps extensor cubiti (three-headed extensor of the fore- arm) ; subanconeus (connects the humerus and posterior ligament of the elbow. The last two are situated posteriorly upon the arm. Fourth.— Cubital (situated upon the forearm), 20 pairs,— of these the first eight are anterior ; the last twelve, posterior : — flexor longus pollicis (long flexor of the thumb) ; flexor carpi ulnaris (ulnar flexor of wrist); flexor carpi radialis (radial flexor of the wrist); flexor profundus digitorum (deep flexor of the fingers); flexor sublimis digitorum (high flexor of the fingers) ; pronator radii teres (round pronator of the radius) ; pronator quadratus (square pronator); palmaris longus (long of the palm); extensor indicis (extensor of the index finger); extensor carpi ulnaris (“ulnar extensor of the wrist”) ; extensor minimi digiti (extensor of the little finger); extensor carpi radialis brevior (shorter radial extensor of the wrist); extensor carpi radialis longior (longer radial extensor of the wrist); extensor communis digitorum (common extensor of the fingers) ; ex- tensor ossis metacarpi pollicis (extensor of the metacarpal bone of MYOLOGY. 155 the thumb) ; extensor primi internodii pollicis (extensor of the first plalangeal bone of the thumb) ; extensor secundi internodii pollicis (extensor of the second plalangeal bone of the thumb); supinator brevis (short supinator) ; supinator longus (long supinator); and anconeus (“ elbow-muscle : ” aids extension of the forearm). Fifth.— Thenal (forming the ball of the thumb), 4 pairs: abductor pollicis (abductor of the thumb); adductor pollicis (adductor of the thumb); flexor brevis pollicis (short flexor of the thumb); and opponens pollicis (or flexor of the thumb). Sixth.— Hypothenal (on the ulnar side of the palm), 4 pairs : abductor minimi digiti (abductor of little finger) ; flexor minimi digiti (flexor of little finger); opponens minimi digiti (opposition placer of the little finger) ; palmaris brevis (short muscle of the palm). Seventh.— Palmar, 3 sets in each palm, containing 11 muscles. The three sets are the lumbricales (“earthworms,” named from their appearance), 4 in number. (These muscles are aids, or parts, of the deep flexor. They arise from its tendons [in the foot they arise from the tendons of the long flexor], and are inserted into the aponeuroses of the common extensor of the fingers) ; interossei palmares, 3 in number (extend from the palmar surface of the metacarpal bones to the side of the bones of the first phalanx) ; and the interossei dorsales, 4 in number (extend from the sides of the metacarpal bones to the sides of the bones of the first phalanx). MUSCLES OF THE LOWER EXTREMITY (Fifty-two Pairs and Sets in Twelve Groups). First.— Intra-abdominal (within the abdomen), 3 pairs: psoas mag- nus (great loin muscle) ; psoas parvus (not constant; it connects the vertebral column with the brim of the pelvis) ; and iliacus (iliac muscle; lies in the iliac fossa). Second.— Anterior femoral, 7 muscles in each lower limb : tensor vaginae femoris (tightener of the sheath of the thigh); sartorius (tailor’s muscle, longest in the body); rectus femoris (straight of the thigh); vastus internus, vastus externus (named from their position and extent; they help to form the anterior portion of the thigh); crureus (inseparably connected with the vastus internus) ; and subcrureus (connects the synovial pouch of the knee with the shaft of the femur above the pouch). Third.— Posterior femoral, 3 muscles, or 3 pairs in both limbs : biceps flexor cruris (two-headed flexor of the thigh) ; semitendinosus (has a very long tendon, and a tendinous intersection: connects 156 MYOLOGY. the ischium and tibia) ; and semimembranosus (has a membranous expansion: it connects the ischium and tibia). Fourth.— Internal femoral, 5 muscles: gracilis (“slender,” extends from the pubis to the tibia); pectineus (extends from the pubis to the shaft of the femur, just below the smaller trochanter) ; adduc- tor longus, adductor brevis, adductor magnus (“long,” “short,” and “great adductors” of the thigh. They are all attached to the linea aspera of the femur and to the pubis. The latter is also attached to the lower part of the ischium. The adductor magnus is inserted into the whole length of the linea aspera). Fig. 99. Fifth.— Gluteal, or upper posterior, 9 muscles: gluteus maximus, glu- teus medius, gleuteus minimus (“greatest,” “middle,” and “least breech ” muscles: they abduct the thigh, and assist station and progression); gemellus superior, gemellus inferior (“upper” and “lower twins”: they extend from the ischium to the great tro- chanter) ; obturator externus, obturator internus (extend from the pelvis to the great trochanter, and take their name from the obturator [closed up] foramen, whence they arise); pyriformis (“pear shape”: is partly within the pelvis, and extends to the great trochanter) ; and quadratus femoris (“square of the thigh”). Fig. ioo. MUSCLES OF THE BACK OF THE LEG DEEP LAYERS. 158 MYOLOGY. Sixth.—Popliteal (in the popliteal space), i muscle — popliteus “ham muscle” : it forms the floor of the popliteal space, from outer con- dyle to the shaft of the tibia). Seventh.—Superficial posterior crural, 3 muscles: gastrocnemius (“belly, [or calf] of the leg”: this, and the two following, form the tendo Achillis) ; soleus (shaped like the sole of a shoe: it lies within or beneath the gastrocnemius); and plantaris (extends from the femur to the os calcis: has a long, delicate tendon). Fig. ioi. Fig. 102. MUSCLES OF THE SOLE OF THE FOOT FIRST LAYER. Fig. 103. MUSCLES OP THE FRONT OF THE LEG. 160 MYOLOGY. Eighth.— Deep posterior crural, 3 muscles: flexor longus pollicis (long flexor of great toe), flexor longus digitorum (long flexor of the toes), and tibialis posticus (posterior tibial). Fig. 104. MUSCLES OF THE SOLE OF THE FOOT — SECOND LAYER. Ninth.— Anterior crural, 3 muscles: extensor proprius pollicis (proper extensor of the great toe), extensor longus digitorum (long extensor of the toes), and tibialis anticus (anterior tibial). MYOLOGY. 161 Tenth.— Peroneal (in the region of the perone, or fibula), 3 muscles: peroneus brevis, peroneus tertius, and peroneus longus (‘‘short,” “third,” and “long peroneal”) ; they extend from the fibula to the metatarsal bones, and extend the foot upon the leg; the latter everts the sole of the foot. Fig. 105. MUSCLES OF THE SOLE OF THE FOOT — THIRD LAYER. Eleventh.— Superior pedal (upper part, or dorsum, of the foot), I mus- cle : extensor brevis digitorum (short extensor of the toes). 162 MYOLOGY. Twelfth.— Inferior pedal (under part, or sole of the foot), n muscles and sets. The last are in four layers, counted from the skin to the bones:— First layer contains the abductor pollicis, flexor brevis digitorum, and abductor minimi digiti — 3 muscles. Second layer contains the flexor accessorius and the 4 lumbricales — 1 pair and 1 set. Fig. 106. MUSCLES OF THE SOLE. Third layer contains the flexor brevis pollicis, the adductor pollicis. flexor minimi digiti, and the transversus pedis (transverse of the foot)—4 muscles. Fourth layer contains the dorsal and plantar interossei—2 sets, or 7 muscles. There are four dorsal and three plantar interossei, counting from within outward, as we count the bones of each plalanx. The dorsal interossei and lumbricales are found in both the upper and lower extremities, and consequently are counted twice as sets ; but the aggregate of muscles is correctly given as 652 (324 pairs and 4 single). MYOLOGY. 163 There are 44 groups of muscles: 12 of the head, 9 in the neck, 4 in the trunk, 7 in the upper extremity, and 12 in the lower. The grouping facilitates study and aids the memory. The grouping already given has reference to the position, or situation of the muscles in the body. The muscles may also be grouped with reference to their function, or office. We mention a few in illustration, and also describe them. The muscles of respiration include the muscles of iaspiration and expiration. The ordinary muscles of inspiration are the diaphragm, three scalene, the levatores costarum, and the external intercostals. These may be assisted by the serratus posticus superior, the serratus magnus, and the pectoral muscles. The muscles of expiration are : the serratus posticus inferior, the infracostales, some of the abdominal, the sacro-lumbalis, triangularis sterni, and some portion of the internal inter- costals. The muscles of respiration are governed by the pneumogastriy and spinal nerves. The diaphragm (“divider,” separating the cavities of the thorax [chest] and abdomen) is the most important muscle of inspiration, and is supplied by the sympathetic and two phrenic nerves. (The word “phrenic” [Greek the mind] relates to the diaphragm). The diaphragm (or midriff) is a flat muscle, somewhat circular or elliptical in form, attached at its circumference to the walls of the chest (six or seven lower ribs, costal and ensiform cartilages), and having a tend- inous center, called the central tendon. In its passive condition it forms a dome, with its central tendon much higher than its circum- ference ; but when it contracts, its central tendon is drawn downward into the plane of its circumference, and thus the cavity of the chest is enlarged for the reception of the pabulum of life — atmospheric air. The diaphragm is attached to the spine below by two crura (legs), which adhere to the second, third, and fourth lumbar vertebrae, and blend with the anterior common ligament of the spinal column. Several important vessels pass through the diaphragm from the chest to the abdomen, or vice versa, from the abdomen to the chest. For this purpose there are three large openings and several smaller. The large openings are the aortic, the oesophageal, and the caval (for the inferior vena cava). The aortic opening is rather behind than in the diaphragm, since the aorta lies immediately in front of the bodies of the vertebrae at this point, and passes down behind the diaphragm, and between the two crura (legs) which form its lower attachment. The aortic opening transmits the aorta, the thoracic duct, the vena azygos major, and occasionally the left sympathetic nerve. 164 MYOLOGY. The oesophageal opening is above, anterior, and a little to the left of the aortic. It transmits the oesophagus (signifying “ to carry what we eat”) and the pneumogastric (lung and stomach) nerves. The “ caval ” opening is nearer the central part of the diaphragm, and a little to the right of the median line of the body. • The base of the pericardium (heart-case) is attached to the central tendon of the diaphragm, and is drawn downward at every inspiration. Fig. 107. UNDER SURFACE OF THE DIAPHRAGM. Five tendinous arches are found in the posterior margin of the diaphragm ; one in the median line, which forms the anterior part of the aortic opening, and two on either side, for the passage of the psoas mag- nus and quadratus lumborum muscles. The inner arch, nearer the spinal column, passes in front of the psoas magnus (great loin muscle— the surloin of beef) muscle, and receives the name of “ligamentum arcuatum internum” (internal arched ligament). The other arches MYOLOGY. 165 across the upper part of the quadratus lumborum (square of the loins) muscle, and is called the “ ligamentum arcuatum externum ” (external arched ligament). The crura of the diaphragm are also called pillars of the dia- phragm. They are really tendons of the diaphragm. The crura at their origin are tendinous, and blend with the anterior common liga- ment of the spine, as they lie upon the anterior surfaces of the bodies of the lumbar vertebrae. They become fleshy after forming the ten- dinous arch in front of the aorta, decussate (cross), and then diverge so as to surround the oesophagus (gullet) before ending in the central aponeurosis, called the central tendon of the diaphragm. The under surface of the diaphragm is lined or covered by the per- itoneum, which is the serous membrane that lines the abdominal cavity. The upper surface is in contact with three serous membranes — the two plurae, that line the cavities filled by the lungs, and the pericardium (heart-case), which covers the middle portion of the cen- tral tendon. The position of the diaphragm is constantly changing (except its points of attachment) during respiration; and in consequence the position of the organs above and below is constantly changing. The right portion of the diaphragm forms an arch over the convex upper surface of the liver, and supports the concave base of the right lung. The left portion supports the base of the left lung, and covers the great end of the stomach, the spleen, and left kidney. During inspiration the diaphragm contracts, and pushes down the abdominal viscera; at the same time the heart is drawn downward, in connection with the action of the lungs. During expiration the diaphragm is passive, and the action of the abdominal muscles upon the viscera pushes it upward. The anterior and middle scalene muscles extend from the first rib to the transverse processes of the vertebrae directly above. The posterior scalene extends from the second rib to the vertebrae (two or three lower cervical) above. The action of these muscles is to raise and fix the first and second ribs, or bend the spinal column to one side. They are governed by branches of cervical nerves. The lower part of the anterior scalene muscle generally separates the sub- clavian artery and vein. The artery lies behind the muscle with the brachial plexus of nerves. The levatores costarum (lifters of the ribs), twelve on each side, extend from the transverse processes of the vertebrae (the last cervical and first eleven dorsal) obliquely downward and outward to the rib below, near its angle. The first levator costae vel costarum (lifter of the rib, or ribs) extends from 166 MYOLOGY. Fig. 108. MUSCLES OF THE BACK — FIRST LAYER ON THE LEFT. the transverse process of the last (seventh) cervical vertebra to the first rib ; and the muscle for the twelfth rib arises from the eleventh dorsal vertebra. These muscles are supplied by the dorsal nerves. The external intercostals, eleven in number on each side, are attached to the adjacent margins of the ribs above and below, and when they contract, cause the ribs to approximate. Their fibers are directed obliquely downward and forward, like those of the external MYOLOGY. 167 oblique muscle of the abdomen. They are supplied by the intercostal nerves (anterior dorsal, or spinal nerves). The serratus posticus superior is named from its position and form (serra,— a saw). It lies upon the back, between the shoulders, in the third layer, and extends from the ligamentum nuchae and spi- nous processes of three or four vertebrae, downward and outward, to the ribs (second, third, fourth, and fifth), a little beyond their angles. It antagonizes the serratus posticus inferior. The latter is situated also in the third layer of the muscles of the back, but opposite the junction of the dorsal and lumbar regions. It extends from the spinous proc- cesses of the vertebrae (two dorsal and two or three lumbar), upward and outward, to the lower borders of the four lower ribs, a little beyond their angles. The upper serratus is supplied by branches of the cervi- cal nerves ; the lower serratus, by branches of the dorsal. The serratus magnus (great saw-like) muscle is situated at the side of the chest, and is the most important external inspiratory muscle. It extends from the side of the chest beneath the pectoral muscles and shoulder blade, to the vertebral border of the scapula (shoulder blade). Its deep surface rests upon the ribs and intercostal muscles. It arises at the side, by nine fleshy digitations, from the upper border of the eight upper ribs (the second rib having two points of attachment). It is a broad, thin muscle. The direction of its fibers is generally upward and backward, but those of its middle portion are nearly horizontal. The lower portion (four lower digitations) inter- digitates with processes of the external oblique muscle (one of the abdominal). The subscapular muscle lies between this muscle (ser- ratus magnus) and the scapula, giving us two muscles between the shoulder blade and ribs. It is supplied by the posterior thoracic nerve (long thoracic, external respiratory of Bell). This nerve has two or three roots from the lower cervical nerves. The pectoral muscles are the pectoralis major and pectoralis minor. (See list of illustrations for muscles of the chest, etc. They take their name from size and position (pectus,—breast; major and minor,— greater and less). The greater is the more superficial, and covers the entire breast from the sternum and clavicle to the shoulder, being inserted into the bicipital groove of the humerus. The smaller is beneath, and extends from three of the ribs (third, fourth, and fifth) to the coracoid (raven-like) process of the scapula. These muscles are supplied by branches of the brachial plexus of nerves. (The brachial plexus is formed by the intermixture of the anterior branches of the four lower cervical and first dorsal nerves.) The infra-costales (within the ribs) are not constant. When found, 168 MYOLOGY. they descend obliquely from one rib (costa) to another. The abdom- inal muscles (excepting the cremaster) assist expiration, by compress- ing the contents of the abdomen against the diaphragm. They also flex the vertebral column. They are chiefly named from the direction of their fibers,— straight (rectus), transverse (transversalis), exter- nal and internal oblique. The pyramidal and quadratus lumborum are named from their shape, and the cremaster (suspender) from its function of suspending the testicle. Fig. 109. MUSCLES OF THE CHEST, AND BICEPS OF THE ARM. The straight (recti) muscles of the abdomen — one on each side of the median line of the body — extend from the pubes directly upward to the ensiform and costal cartilages of the chest. They are partly tendinous, so as to seem composed of three or four shorter muscles. Each rectus is inclosed in a sheath, formed by the apo- MYOLOGY, 169 neuroses of the oblique and transverse muscles of the abdomen along the upper three fourths of its course, but the posterior wall of the sheath terminates at the commencement of the lower fourth of the muscle, leaving it separated from the peritoneum only by the trans- versalis fascia. The external oblique is the most superficial of the three flat muscles covering the anterior of the abdomen; the internal oblique Fig. no. EXTERNAL OBLIQUE MUSCLE, AND SPERMATIC CORD. lies next; and the transverse is the most internal, and nearest to the peritoneum, which covers the bowels,— or we may remember that the internal oblique forms the middle layer. The sheath of the rectus, along the upper three fourths of its length, is really formed by the aponeurotic plates of the internal oblique muscle but blends with the aponeuroses of the transverse behind and the external oblique in front 170 MYOLOGY. The fibers of the external oblique run downward and inward, nearly parallel with Poupart’s ligament; the fibers of the internal oblique run upward and inward, crossing the former nearly at right angles; the transverse run nearly horizontal, and the recti (if we speak of the two), vertically. The external oblique is fleshy at the side and apo- neurotic in front. Its aponeuroses form the linea alba (“white line,” concealed by the integument), Poupart’s and Gimbernat’s ligaments, Fig. hi. THE INTERNAL OBLIQUE AND CREMASTER MUSCLES. and the external abdominal ring. It is an important muscle, on account of its connection with inguinal hernia (rupture in the groin). It is a large muscle, extending from the pectoralis major above to the crest of the ilium and pubes below. It interdigitates at the side of the body with two muscles (the serratus magnus and latissimus dorsi), MYOLOGY. 171 where it is attached to the ribs, and is irregularly quadrilateral in form. The internal oblique extends from the outer half of Poupart’s liga- ment and the crest of the ilium to the linea alba and cartilages of the four lower ribs (ninth, tenth, eleventh, and twelfth). Its lower border forms the upper boundary of the inguinal (in the male sometimes called the spermatic) canal. At the crest of the pubes (or pubis, spelled both ways in the lexicons) this muscle (internal oblique) unites with the transverse (transversalis), to form what is called “the con- joined tendon of the internal oblique and transversalis.” This tendon constitutes a strong aponeurosis behind the external abdominal ring (external opening of the inguinal canal beneath the integument). The transverse muscle of the abdomen extends from the outer part of Poupart’s ligament, the crest of the ilium, lumbar fascia, and cartilages of the six lower ribs, to the crest of the pubes and linea alba. The lower and internal portion of the muscle lies beneath and behind the inguinal canal. The abdominal muscles are supplied by branches of the dorsal and lumbar nerves (spinal nerves). The lumbar fascia (loin bandage) is only another name for the broad aponeurosis (expanded tendon) of the transverse muscle, blended with other aponeuroses. It divides into three layers, and contains between its anterior and middle layers the square muscle of the loins (quadratus lumborum), and between its middle and posterior layers the erector spinae. The quadratus lumborum extends along the side of the spine between the crest of the ilium and lower rib The sacro-lumbalis muscle is a part of the erector spinae. It lies upon the back, and extends from the sacrum and back part of the crest of the ilium upward to the angles of the six lower ribs. The triangularis sterni (triangular of the sternum [breast-bone]) is situated upon the inner wall of the front of the chest, and lies between the sternum and the pleura. It arises from the lower part of the sternum, from the inner surface of the ensiform cartilage, and from the costal cartilages of the lower true ribs (three or four of them), and is inserted by fleshy digitations into the lower border of the costal (rib) cartilages of the ribs above (the second, third, fourth, and fifth). It serves to draw these costal (rib) cartilages together, and thus com- press the chest. The internal intercostals (muscles between the ribs) lie on the inner surface of the external intercostals, and extend, in each case, from the border of the rib below to the border of the rib above. Their fibers run, obliquely upward and forward, across the fibers of the 172 MYOLOGY. Fig. i12. TRANSVERSE AND RECTUS MUSCLES OF THE ABDOMEN. external intercostals, which run upward and backward. This crossing of fibers contributes to the strength of the chest walls. The pyramidalis lies in front of the lower part of the rectus. It is triangular in form, as its name implies, with its base resting on the pubes, and its apex terminating in the linea alba half way to the umbili- cus. When the pyramidalis is wanting, the lower end of the rectus muscle is larger. MYOLOGY. 173 The cremaster has its origin and insertion in the lower fibers of the internal oblique, or, more properly, is identical with them. The lumbar fascia and cremaster muscles are not included among the muscles of expiration. , The muscles of deglutition (swallowing) are the muscles of the tongue, the elevators of the hyoid bone, the three constrictors of the pharynx (throat), the stylo-pharyngeus, palato-glossus, palato-pharyn- geus, tensor palati, and the muscular fibers of the oesophagus (gullet). Deglutition is divided into three periods. During the first period the contents of the mouth are carried into the pharynx; during the second, into the oesophagus; and during the third into the stomach. The first period is controlled by voluntary muscles. The muscles of deglutition are controlled by the cervical portion of the sympathetic and branches from five pairs of cranial nerves (trifacial, facial, hypoglossal, glosso-pharyngeal, and pneumogastric). The muscles of the tongue are described with that organ. The elevators of the hyoid bone are the digastric (two bellies), stylo-hyoid, mylo-hyoid, and genio- hyoid. The digastric is a small muscle below the side of the lower jaw, ex- tending indirectly from the mastoid process of the temporal bone behind the pinna, or auricle (the external ear) to the lower border of the jaw, close to the median line. Its two bellies are the anterior and posterior, and they are separated by the central tendon, which passes through a loop in the tendon of the stylo-hyoid muscle near the hyoid bone. The anterior belly is supplied from the motor root of the fifth cranial nerve, and the posterior belly from a branch of the seventh cranial (facial). The stylo-hyoid (styloid process and hyoid bone) is a small, slender muscle in front of the posterior belly of the digastric. The name indi- cates its attachments — supplied by the facial nerve. The mylo-hyoid is a flat, triangular muscle attached to the lower iaw and hyoid bone, as is indicated by the name. It forms with its fellow a muscular floor for the cavity of the mouth — supplied by a branch of the fifth cranial nerve, or (what amounts to the same) by the mylo-hyoid branch of the inferior dental nerve (branch of the fifth). The genio-hyoid (chin and hyoid bone) extends from the inner side of the symphysis menti (union of the chin) directly downward and backward to the hyoid-bone. Supplied by the hypoglossal (cranial) nerve. The three constrictors of the pharynx are placed one below another, and are named, from their position, the superior, middle, and inferior. The lower overlaps the middle constrictor, and the middle overlaps the upper, the lower being most superficial, and also the 174 MYOLOGY. thickest. These three muscles may in some respects be described together. They all lie without (or are lined by) two membranes — the mucous membrane of the pharynx (throat), and a fibrous membrane called the “ pharyngeal aponeurosis ” ; they are all connected, posteri- orly, to a fibrous raphe (seam) in the median line; and they are all incomplete, anteriorly, and bring to their aid the tongue and larynx, Fig. i13. MUSCLES OF THE NECK — ANTERIOR VIEW. which lie in front. The inferior constrictor is attached, in front, to the cricoid and thyroid cartilages (parts of the larynx); the middle con- strictor to the hyoid bone and stylo-hyoid ligament; and the superior constrictor to the internal pterygoid plate, the pterygo-maxillary (ptery- goid process and lower jaw) ligament, lower jaw, and tongue. From these points of attachment, in front, the fibers of these muscles curve backward to the median raphe, and the superior constrictor is, in addi- tion, prolonged by means of an aponeurosis to the pharyngeal spine on the basilar process of the occipital bone. The three muscles are all in relation, posteriorly, with the vertebral column, and are supplied by branches from the sympathetic and pneumogastric nerves. MYOLOGY. 175 The stylo-pharyngeus is a long, slender muscle, and extends, as its name implies, from the styloid process, downward and inward, along the side of the pharynx, to the lower constrictor muscles and thyroid cartilage; supplied by the glosso-pharyngeal nerve. The palato-glossus will be described with the tongue, but, as it assists in swallowing, should be mentioned here. It is called some- times the constrictor isthmi faucium (constrictor of the isthmus of the Fig. 114. THE CONSTRICTOR MUSCLES — SEEN FROM BEHIND. fauces), because it narrows the passage between the mouth and throat (pharynx). Covered with the mucous membrane of the mouth and throat, it forms the anterior pillar of the soft palate, and extends from the soft palate (velum palati, or veil of the palate) on either side of the uvula (or uvule), to the side of the tongue at its back part, in front of the tonsil. It causes the soft palate and side of the tongue to approxi- mate. It is supplied from Meckel’s ganglion (a part of tne sympathetic system). 176 MYOLOGY. The palato-pharyngeus (palate and throat), with its mucous cover- ing, forms the posterior pillar of the soft palate. It is separated from the palato-glossus (palate and tongue) by a triangular interval, that forms the lateral (side) boundary of the isthmus faucium (isthmus of the fauces, or simply the fauces). It is at the base of this interval that the tonsil lies — one on either side. The muscle extends from the soft palate to the side of the pharynx and thyroid cartilage. It is supplied from Meckel’s ganglion. During the first period of deglutition (swallowing), the food is car- ried into the fauces by the pressure of the tongue against the hard palate (roof of the mouth), the larynx being at the same time raised with the pharynx, and carried forward under it. During the second period the food is carried by the constrictor muscles into the cesoph- agus (gullet); and during the third into the stomach, by the muscular fibers of the oesophagus, which are continuous with the fibers of the inferior constrictor of the pharynx. The food is prevented from entering the posterior nares (nostrils) by the elevation and tense condition (by action of the tensor palati) of the soft palate, and from entering the mouth by approximation of the palato-pharyngeus (palate and throat) muscles and uvula. The latter (the uvula) fills up the slight interval between the two muscles. The muscles of mastication are the temporal, masseter, buccina- tor, internal, and external pterygoid. (See list of illustrations.) They are all supplied by the inferior maxillary nerve — a branch of the fifth pair of cranial nerves. The buccinator has also, some branches from the facial, which is a part of the seventh pair. The temporal muscle lies in the temporal fossa, passes beneath the zygomatic arch, and is inserted into the coronoid (crow-like) proc- ess of the lower jaw. The coronoid process is straight, like the crow’s beak, while the coracoid is curved like the beak of a raven. The masseter extends from the zygomatic arch and malar process of the upper jaw to the ramus and angle of the lower jaw. The buccinator (trumpeter, used in blowing wind instruments) occupies the interval between the jaws at the side of the face. It is attached to the outer surface of the alveolar processes of the upper and lower jaws, opposite the molar teeth, and to the anterior border of the ligament (pterygo-maxillary), which connects the pterygoid process with the internal surface of the lower jaw, and extends forward to blend with the fibers of the muscles near the angle of the mouth. It lies next to the mucous membrane of the mouth, and is covered in part by the masseter and other muscles. The internal pterygoid (see figures of pterygoid muscles) resent- MYOLOGY. 177 bles the masseter in form and in the direction of its fibers. It extends from the pterygoid fossa of the sphenoid bone downward, outward, and backward, to the inner surface of the ramus and angle of the lower jaw. It lies close to the superior constrictor of the pharynx. The external pterygoid muscle consists of two portions. One portion is attached to the posterior surface of the upper jaw and palate bones, and the other, higher up, to the great wing of the sphenoid. Fig. 115. THE TEMPORAL MUSCLE, LYING IN THE TEMPORAL FOSSA. Both portions are inserted into the neck of the condyle of the lower jaw, and the fibro-cartilage of the joint (temporo-maxillary). These two portions together form a muscle somewhat conical in form, and extending almost horizontally between the zygomatic fossa and con- dyle of the jaw. It draws the lower jaw directly forward, one side at a time, or both sides together. The eight muscles of the larynx (ninth group of the neck) form the muscles of phonation (use of the voice), and will be described with the larynx. They are supplied by branches of the sympathetic and pneumogastric nerves ; or, more particularly, by the superior and inferior (also called “recurrent”) laryngeal nerves. The muscles of expression include seven groups of the cranium and face (the first, fourth, sixth, seventh, eighth, ninth, and tenth), 178 MYOLOGY containing 61 muscles — 30 pairs and 1 single. These are nearly all controlled by the facial (seventh cranial) nerve. The biceps muscles are flexors, both in the leg and arm ; the triceps muscles are extensors in both the leg and arm. The biceps of the arm is anterior ; that of the leg posterior. This is because the leg is flexed backward and the arm forward. The triceps of the thigh is anterior, and the triceps of the arm posterior, for the same reason. The tendon of the biceps femoris forms the outer hamstring ; the inner hamstring is formed by four muscles (gracilis, sartorius, semi- Fig. 116. THE PTERYGOID MUSCLES. membranosus, and semitendinosus). These hamstrings can be easily felt under the knee when the leg is flexed at a right angle as in sitting, and the muscles are slightly contracted. The gastrocnemius and soleus together form the calf of the leg, and since the gastrocnemius has two heads, these muscles are sometimes called the triceps surae (three-headed of the calf of the leg), or,extensor pedis (extensor of the foot). They are inserted into the os calcis by means of the tendo Achillis, and extend the foot; or, when the person is standing, raise him upon the toes. The two heads of the gastrocnemius arise from the upper and back part of the condyles of the femur. The soleus arises from the head and upper part of the fibula and shaft of the tibia. Fig. 117. MUSCLES OF THE BACK OF THE LEG — SUPERFICIAL LAYER. 180 MYOLOGY. The leg is flexed upon the thigh by the muscles that form the ham- strings already mentioned. The popliteus also aids the hamstring muscles to flex the leg. The leg is extended by the quadriceps extensor, which is made up of four muscles (rectus, crureus, vastus externus, and vastus internus), and is attached to the patella. The forearm is flexed chiefly by the biceps and anterior brachial (brachialis anticus), and extended by the triceps and anconeus. We shall briefly describe some of the larger and more important muscles, and refer the reader to other works for a more definite descrip- tion of the rest. Fig. 118. OCCIPITO-FRONTALIS, AND EXTERNAL MUSCLES OF THE EAR. A. Attollens Aurem. B. Attrahens Aurem. C. Retrahens Aurem. D. Part of the Orbicularis Palpebrarum. The occipito frontalis covers the head from the occiput to the eye- brows. Its middle part, which covers the vertex (crown of the head), is aponeurotic ; its extremities fleshy. Some anatomists regard this as a single muscle. Its frontal portion is connected or joined with the muscle of the opposite side ; but its occipital portion is separated from its fellow by a variable interval. It raises the eyebrows, corrugates the forehead transversely, and moves the scalp : controlled chiefly by the facial nerve. The platysma myoid (broad, muscle-like) is superficial, lying next to the skin. (See “muscles of the head, face, and neck,” in list of illustrations.) It covers the side of the neck, extending from the clavicle MYOLOGY. 181 and areolar tissue (or fascia) that covers the pectoral muscles to the chin and lower jaw. Its fibers are parallel with each other, and pass obliquely upward and inward. It draws down the lower lip and angle of the mouth as in the expression of melancholy — governed by the facial nerve. The sterno-cleido-mastoid (sternum-clavicle and mastoid process; its name indicating its origin [from the sternum and inner end of the clavicle] and insertion [into the mastoid process]) passes obliquely across the side of the neck. There is usually a triangular interval Fig. 119. MUSCLES OF THE NECK AND BOUNDARIES OF THE SURGICAL TRIANGLES. between its sternal and clavicular origins; but the clavicular origin may be wanting, or may be very wide. The muscle is rendered very prominent when the head is turned toward the opposite side. It rotates the head to one side when one muscle acts singly; acting together, the two bend the head directly forward. This muscle is in close relation with important blood-vessels and nerves (common carotid artery, jugular veins, pneumogastric and spinal accessory 182 MYOLOGY. nerves), and serves to mark the division between the anterior and pos- terior triangles of the neck. The external jugular vein lies between this muscle and the platysma myoid ; the internal jugular, the carotid artery, and pneumogastric nerve beneath this muscle. It is governed by the spinal accessory nerve (one of the cranial nerves). The trapezius (see muscles of the back) is a large, flat, superficial muscle in the form of a triangle. The base of the triangle extends from the head (the occipital bone) along the spine to the loins (or to the last dorsal vertebra). The vertex of the triangle is at the shoulder (the acromion process of the scapula). The fibers of the muscle aris- ing from the spinal column converge toward the shoulder, where they adhere to the spine of the scapula, acromion process, and outer end of the clavicle. The two muscles (one on each side of the spine, or spinal column) taken together form a trapezium, or diamond-shaped quadrangle; two opposite angles corresponding to the shoulders, and the other two to the occipital protuberance and last dorsal vertebra. The anterior margin of this muscle in the neck extends from the clav- icle below to the occipital bone above, and forms the posterior bound- ary of the posterior triangle of the neck. The trapezius moves the shoulder, elevating, depressing, or carrying it backward, by the sepa- rate action of its various parts. It also draws the head backward and to one side. It is controlled by branches of the spinal accessor) nerve. The latissimus dorsi is also a large, flat, and, for the most part, superficial muscle. It covers the region of the loins (lumbar region). The lower part of the trapezius overlaps its upper dorsal portion. It extends from the lower half of the spinal column (six lower dorsal, and all the lumbar vertebrae and sacrum) to the bicipital groove of the humerus. It is also attached to the back part of the crest of the ilium, and to three or four lower ribs. The latissimus dorsi draws the arm backward and downward ; or when the arm is fixed, as in climbing, it draws up the trunk. By fixing the arms, asthmatic patients cause it to act as a muscle of inspiration, by drawing up the lower ribs. It is governed by the long subscapular nerve from the brachial plexus (a network of branches from the four lower cervical and first dorsal of the spinal nerves). The deltoid (delta-like) covers the shoulder joint. It is attached to the outer third of the clavicle, and to the acromion process and spine of the scapula; and since these parts are movable, and are also attached to the trapezius muscle, whose fibers run in nearly the same direction, the deltoid may in some sense be considered as an extension of the trapezius, although the two are entirely distinct. The deltoid Fig. 120. MUSCLES OF THE BACK. 184 MYOLOGY. is inserted into the outer surface of the humerus, a little above its mid- dle, by means of a strong tendon. It moves the arm as the trapezius moves the shoulder, directly upward from the side, so as to bring it at right angles with the trunk, and by aid of other muscles forward or backward. It is supplied with stimulus from the circumflex nerve from the brachial plexus. Fig. 121. THE TRICEPS AND MUSCLES ON THE BACK OF THE SCAPULA. The supraspinatus (occupying the supraspinous fossa of the scap- ula), the infraspinatus (occupying the infraspinous fossa, i. e., below the spine of the scapula), and the teres minor (from the axillary bor- der of the scapula), are inserted respectively into the highest, middle, and lowest facets upon the greater tuberosity of the humerus, or, we may say, at the upper part of the anatomical neck of the humerus. The teres minor is supplied by the circumflex, and the other two by the suprascapular nerve. The supraspinatus raises the arm. The infraspinatus and teres minor rotate the humerus outward. These MYOLOGY. 185 Fig. 122. MUSCX.ES OF THE CHEST AND FRONT OF THE ARM. muscles also afford great protection to the shoulder joint from disloca- tion. The teres major (“greater round” muscle [see muscles on the dorsum of the scapula”]) extends from the scapula (near the inferior angle) to the bicipital groove of the humerus. It rotates the arm 186 MYOLOGY. inward and carries it backward; supplied by the lower subscapular nerve. The two tendons of this muscle and the latissimus dorsi are separated at their insertion into the humerus by a synovial bursa. The subscapularis (under the scapula) lies beneath the scapula, and extends from the subscapular fossa to the smaller tuberosity of the humerus. It acts with the teres major to rotate the arm inward. It is governed by the subscapular nerves from the brachial plexus. The biceps flexor cubiti, or, simply “biceps,” of the arm, is the main flexor of the forearm. It is situated at the anterior and internal part of the arm, and extends from the upper edge of the glenoid cavity and from the coracoid process to the radius, just below the elbow (to the tubercle, or tuberosity of the radius). It extends along the humerus, but is not attached to it. It is controlled by the musculo-cutaneous nerve, which is a branch of the brachial plexus. The latter is formed by branches of the spinal nerves (four cervical and one dorsal). The triceps extensor cubiti, or triceps of the arm, is situated on the back of the arm, and extends the entire length of the humerus. It is divided above into three parts, as its name (triceps, three-headed) implies. The long head arises from the inferior margin of the glenoid cavity and capsular ligament, and the other two heads (the “ outer and “inner”) from the shaft of the humerus. These three portions unite about the middle of the arm, and form one powerful muscle which is inserted into the olecranon process of the ulna at the elbow, It extends the forearm, and is the direct antagonist of the biceps and anterior brachial. It is supplied by the musculo-spiral nerve. The psoas magnus (great loin muscle) is partly wirhin the cavity of the abdomen, and emerges from the abdominal cavity beneath Pou- part’s ligament, in connection with the iliacus. It is attached to the spinal column (one on either side) from the last dorsal vertebra to the sacrum, and is inserted by a tendon, common to this and the iliacus, into the smaller trochanter of the femur. It rotates the thigh outward, and bends it upon the pelvis, or the pelvis upon the thigh. It is sup- plied by branches of the lumbar nerves. The iliacus (iliac muscle) occupies the internal iliac fossa, and blends below with the psoas magnus. It is supplied by the anterior crural nerve (the largest branch of the lumbar plexus). The lumbar plexus is formed by the anterior branches of the four upper lumbar nerves. The latter are spinal nerves. The sartorius (tailor’s muscle) extends from the ilium (from the anterior superior spine of the ilium) to the tibia (inner surface of the shaft near the crest, or shin). It is the longest in the body. (See muscles of the iliac, etc.) Near the groin it forms the outer bound- Fig. 123. MUSCLES OF THE ILIAC AND ANTERIOR FEMORAL REGIONS. Fig. 124. MUSCLES OF THE HIP AND THIGH. MYOLOGY. 189 ary of Scarpa’s triangle. The latter is a triangular space formed by Poupart’s ligament above and by the borders of two muscles (the sartorius and adductor longus) at its sides. In this triangle the femoral artery and femoral vein are quite superficial. The artery passes perpendicularly through the center of this space, and lies between the vein and the anterior crural nerve. The nerve is out- side of the artery. The sartorius serves to cross the legs, as the tailor sits upon his bench. It is supplied by the anterior crural nerve. The rectus femoris (straight of the thigh) and two vasti (vastus internus and vastus externus) make up the triceps extensor cruris, or simply the triceps of the leg. It is the “kicking” muscle, or great ex- tensor. The three parts are inserted by a common tendon into the patella at the knee, and through the patella and ligament (ligamentum patellae) below into the tubercle of the tibia. The rectus has two origins, or two tendons, called the straight tendon and the reflected tendon. The straight tendon is attached to the anterior inferior spine of the ilium, and the reflected tendon to the upper border of the acetab- ulum. The vastus externus is attached to the whole length of the linea aspera, and to the anterior border of the great trochanter. The vastus internus is attached to the linea aspera and to the inner surface of the femur. These three muscles, uniting to form one tendon, are all gov- erned by the anterior crural nerve. The biceps flexor cruris, or biceps of the leg, is situated on the posterior part of the thigh. Its long head extends from the tuberosity of the ischium to the head of the fibula below the knee. Its short head is attached to the whole length of the linea aspera, between the adductor magnus and vastus externus. The fibers of the long head terminate in an aponeurosis, which covers the posterior, or outer surface of the muscle, and receives the fibers of the short head, which spring from the shaft (the linea aspera,— the rough posterior portion of the shaft) of the femur. The aponeurosis becomes gradually contracted into a tendon (the outer hamstring), which is inserted into the outer side of the head of the fibula, and embraces the external lateral ligament of the knee. The three muscles (biceps, semimembranosus, and semitendinosus) forming the posterior femoral group, are all governed by the great sciatic nerve. The office of the seven orbital muscles has already been given. They are all situated within the orbit and around the eyeball. All but one (the inferior oblique) have their origin at the back part of the orbit, behind the eyeball; and, again, all but one (the levator palpebrae) are inserted into the sclerotic coat of the eyeball. The inferior oblique arises from a depression in the orbital plate of the superior maxillary Fig. 125. DEEP MUSCLES OF THE FEMORAL REGION — INNER SIDE. MYOLOGY. 191 hone, external to the lachrymal groove; and the levator palpebras is inserted into the upper, or posterior border of the upper tarsal cartilage. The four recti (superior, inferior, internal, and external rectus) muscles are situated, as their name implies, above, below, on the inner, and on the outer side of the eyeball, and are inserted into the sclerotic coat about one third of an inch (one centimeter) from the margin of the cornea (the cornea lies in front of the colored portion of the eye). The superior oblique is situated at the upper and inner side of the orbit, internal to the levator palpebrae. It passes from the back part of the orbit forward to the inner angle of the eye, where it passes through a loop, or ring of fibro-cartilage, that acts as a pully to change its direc- tion. From the pulley it passes outward above the eyeball, but beneath Fig. 126. MUSCLES OF THE ORBIT. the superior rectus muscle to the outer part of the globe, where it is in- serted into the sclerotic coat. When it contracts, it moves the upper Part of the globe toward the median line of the body, or toward the other eye. The inferior oblique passes outward beneath the eyeball and inferior rectus, between the external rectus and eyeball, to be inserted near the insertion of the superior oblique, which it antagonizes, or counterbalances. It rotates the lower part of the globe inward. These oblique muscles act spontaneously when we incline the head to one side, and thus con- fine the image of any object viewed to the same parts of the retina (the retina is a thin, semitransparent membrane that lines the interior of the eyeball, and surrounds the vitreous body. It receives the image of all objects viewed). 192 MYOLOGY. The superior oblique muscle is governed by the “pathetic” (fourth cranial) nerve; the external rectus by the “abducens” (the sixth cranial) nerve; and all the other orbital muscles by the “motor oculi” (mover oh the eye, or “motores oculorum” [movers of the eyes], the third cranial) nerve. The deep fascia of the thigh is the most extensive of all the deep fasciae of the body, and is called the “fascia lata” (broad bandage). It Fig. 127. FASCIA LATA AND SAPHENOUS OPENING. is also called the “ vagina femoris ” (sheath of the thigh). It envel- opes all the muscles of the thigh, and sends off from its inner surface two strong intermuscular septa (divisions, or partitions between the muscles), which are attached to the whole length of the linea aspera (“rough line” on the back of the thigh-bone) and numerous smaller septa (walls), which separate the individual muscles, and inclose each MYOLOGY. 193 in a distinct sheath. The fascia lata covers the entire thigh, from the crest of the ilium and Poupart’s ligament to the knee. It is thickest at the upper and outer side of the thigh. At the upper and inner part of the thigh (a little below Poupart’s ligament) it has a large, oval-shaped aperture (the “ saphenous opening ”), which transmits the internal saphenous vein to the femoral vein. It is through this open- ing that a femoral hernia (protrusion of the bowel) passes, after descending along the crural (or femoral) canal. It is about an inch and a half (three or four centimeters) in length and half an inch (one or two centimeters) in width. The layer of superficial fascia that covers the saphenous opening is called the cribriform (sieve-like) fascia, because it is pierced, or perforated by numerous openings for blood-vessels and lymphatics. The deep fascia of the arm forms one continuous covering of the shoulder, arm, and forearm, investing the muscles, and sending down septa (divisions) to separate the muscles from each other. Numerous apertures exist in the fascia for the passage of arteries, veins, and nerves. The palmar fascia (bandage of the palm) covers and invests the muscles of the hand. It adheres firmly to the integument by numer- ous fibrous bands, and is thick and strong. Four slips extend upon the fingers, and inclose the tendons of the flexor muscles. The superficial fascia of the thorax is continuous with the fascia of the neck and upper extremities above and of the abdomen below. Opposite the mammary gland it divides into two layers, which inclose the gland, and send septa (partitions) into its substance to support the various lobes. It communicates with the deep fascia which invests the pectoral muscles. MUSCLES THAT MOVE THE THUMB AND FINGERS. In each hand there are 35 tendons, that move the thumb and fingers. These tendons belong to 26 different muscles with 18 differ- ent names. There are 5 flexors, 6 extensors, 2 abductors, 2 adductors, 3 palmar interossei, 4 dorsal interossei, and 4 lumbricales. Three of these muscles (the flexor sublimis digitorutn, flexor profundus digi- torum, and extensor communis digitorum) have each 4 tendons — 1 to each finger ; the rest, 1 each. The tendons of the flexor sublimis digitorum (high flexor of the fingers) are perforated by the tendons of the deep flexor (flexor profundus digitorum). The names of these muscles are as follows: — Fig. 128. MUSCLES OP THE LEFT HAND — PALMAR SURFACE. MYOLOGY. 195 1. Flexor sublimis digitorum (high flexor of the fingers). 2. Flexor profundus digitorum (deep flexor of the fingers). 3. Flexor ossis metacarpi pollicis, or opponens pollicis (flexor of the metacarpal bone of the thumb, or opponent of the thumb : it draws the thumb inward to meet the little finger). Fig. 129. 1. Biceps. 2. Brachialis Anticus. 3. Supinator Longus. 4. Pronator Radii Teres. 5. Flexor Carpi Radialis. MUSCLES OF THE FRONT OF THE FOREARM. 6. Palmaris Longus. 7. Flexor Carpi Ulnaris. 8. Flexor Sublimis Digitorum. 9. Flexor Longus Pollicis. 4. Flexor brevis pollicis (short flexor of the thumb). 5. Flexor longus pollicis (long flexor of the thumb). 6. Extensor communis digitorum (common extensor of the fingers). 7. Extensor ossis metacarpi pollicis (extensor of metacarpal bone of the thumb). 196 MYOLOGY. 8. Extensor primi internodii pollicis (extensor of the first bone of the thumb). 9. Extensor secundi internodii pollicis (extensor of the second, or last bone of the thumb). 10. Extensor indicis (extensor of the index finger). 11. Extensor minimi digiti (extensor of the little finger). 12. Abductor pollicis (abductor of the thumb). 13. Abductor minimi digiti (abductor of the little finger). 14. Adductor pollicis (adductor of the thumb). 15* Opponens minimi digiti (opponent of the little finger). 16. Three palmar interossei (between the bones of the palm). 17. Four dorsal interossei (between the bones of the back of the hand). 18. Four lumbricales (“ earthworms,” from their shape). Fig. 130. TRANSVERSE SECTION THROUGH THE WRIST, SHOWING THE CANALS FOR PASSAGE OF THE TENDONS. The thumb has three extensors — one for each bone, and one for the bone (metacarpal) at its base ; these occupy the back of the fore- arm and hand. It has also three flexors on the palmar surface, an abductor, and an adductor. The fingers are flexed by the flexor sublimus digitorum (high flexor of the fingers) and flexor profundus digitorum (deep flexor of the fingers); and are extended by the extensor communis digitorum (common extensor of the fingers). The flexor sublimis digitorum (high flexor of the fingers) arises at the elbow from the inner condyle of the humerus, coronoid process of the ulna, and from the radius below its tubercle. At the lower third of the forearm it divides into four tendons, which pass together beneath the annular ligament of the wrist, to be inserted into the base of the bones of the second phalanx. Opposite the bones of the first phalanx Fig. 131. FRONT OF THE LEFT FOREARM — DEEP MUSCLES. 198 MYOLOGY. the tendons are split (“perforatus”— perforated), to give passage to the four tendons of the deep flexor. The tendons of the latter are inserted into the base of the bones of the first phalanx. The deep flexor of the fingers (flexor profundus digitorum) arises from the upper two thirds of the ulna and from the interosseous membrane, and divides into four tendons at the middle of the forearm. The little finger has sometimes a special flexor (flexor brevis minimi digiti, or, simply, flexor minimi digiti). It arises from the unciform bone at the wrist, and is inserted into the base of the first bone of the little finger. The extensor communis digitorum (common extensor of the fingers) arises from the external condyle of the humerus at the elbow, and below the middle of the forearm divides into four tendons, which pass beneath Fig. 132. PALMAR INTEROSSEI OF THE LEFT HAND. the annular ligament on the back of the wrist, to be inserted into the second and third phalanges of the fingers. As they pass over the first phalanges, they receive fibers at the sides, from the lumbrical and inter- osseous muscles. On the back of the hand, the tendons of the middle, ring, and little finger are connected by oblique tendinous slips, which associate their action much more than with the other ten- don (to the index finger). The extensor indicis extends the index fin- ger, and the extensor minimi digiti extends the little finger. The four lumbricales are accessories to the deep flexor muscle. They (lumbri- Fig. 133- MUSCLES ON THE BACK OF THE FOREARM. Fig- 134- posterior SURFACE OF THE FOREARM — DEEP MUSCLES. MYOLOGY. 201 cales) arise from the tendons of the deep flexor, and are inserted into the aponeurosis of the extensor tendon on the radial side of the fingers. They were called by the earlier anatomists, “fiddlers’ muscles.” The three palmar interossei arise from the base of the metacarpal bone of one finger, and are inserted into the base of the first bone (first phalanx) of the same finger. The middle finger has none. The four dorsal interossei (between the bones) arise by two heads from adjoining sides of the bases of the metacarpal bones, and are Fig- 135- DORSAL INTEROSSEI OF THE LEFT HAND. inserted into the base of the bones of the first phalanx. In relation to the axis of the hand, they are abductors,— the first and second abducting the index and middle finger toward the thumb, or radial side, the other two abducting the middle and ring finger toward the little finger, or ulnar side ; i. e., the middle finger has two dorsal inter- ossei, one on each side, the index finger has one on the radial side, the ring finger one on the ulnar side, and the thumb and little finger none. The palmar interossei adduct (with reference to the axis of the hand) the index, ring, and little finger. ANGIOLOGY [Vessel-Study). The vessels of the body are the arteries, capillaries, and veins, which carry blood, and the lymphatics, which carry lymph (a clear fluid), or chyle (“juice,”—applied to the nutritive fluid). The special lymphatic vessels that carry chyle are named lacteals. Between the arteries and veins, — i. e., where the arteries end and the veins begin,— are the capillaries, and where the veins end and the arteries begin, is the heart; or if we commence at the heart, and trace the course of the blood throughout the system to the heart again, we shall find that it flows successively through the heart, arteries, capillaries, and veins. The lymphatics convey lymph and chyle into the blood. The blood, like the muscles, moves under the control of the nerves; but, unlike the action of the voluntary muscles, the blood moves, not directly in obedience to the human will, but in obedience to the soul; or, in other words, the emotions (propellers). The special nerves that control the circulation of the blood are called the vaso-motor (vessel- moving) nerves. They arise from the gray matter of the medulla, and the sympathetic ganglia. The heart is sometimes described with the organs of the chest, or with the viscera; but, being the great central organ of the circulation, it is properly described in connection with the blood-vessels. The heart is situated obliquely in the chest, between the lungs. It occupies the middle part of the space between the two pleurae (membranes that invest each lung, separately), which is called the mediastinum. The heart is of conical form, and has its base directed upward, backward, and toward the right. Its average dimensions, in inches, are 5, 3%, and 2y2 \ or in centimeters, about 13, 9, and 7. Its average weight is about 10 ounces; varying in the male from 1 o to 12 ounces, and in the female from 8 to 10 ounces. In proportion to size of body, the female heart is larger. In grams, the average weight of the heart is 311 — 342 in the male, and 280 in the female. The heart is covered in front by the lower part of the sternum (breast-bone), and by the cartilages of the third, fourth, and fifth ribs, but is separated from the chest-wall, except a small area, by lung-tissue. It lies mostly to the left of the median line of the body. Its apex is SYSTEMIC CIRCULATION. (Opp. Page 302). 203 ANGIOLOGY. directed forward, and to the left, and occupies the fifth intercostal space (space between the ribs). The heart is divided by a muscular septum (partition) into two lateral halves, named respectively the right and left sides of the heart; but the heart is so obliquely placed, not only as to the general direction of the heart with reference to a vertical line, but also with reference to the muscular septum and sides of the body, that the “right side ” of the heart really occupies the greater part of its anterior portion ; while the “left side” occupies largely its posterior portion, but extends somewhat farther to the left than the right side of the heart. Fig. 136. RIGHT AURICLE AND VENTRICLE. Each side of the heart contains an auricle and ventricle. The right auricle and right ventricle are in the right side of the heart, and the left auricle and ventricle in the left side. In passing from the right side of the heart to the left side, the blood is compelled, in the adult, to pass through the lungs. In foetal life, when no air reaches the lungs, the blood passes through an opening (the foramen ovale) in the muscular septum, directly from the right to the left side of the heart. Soon after birth the foramen ovale generally becomes closed. 204 ANGIOLOGY. The heart is wholly inclosed by a serous membrane, called the peri- cardium (“around the heart”), or heart-case. Within this encasement the heart moves freely. The pericardium extends upward, and surrounds the great vessels (the aorta, the pulmonary artery and veins, and the superior vena cava), about two inches (five centimeters) above their origin at the heart. The pericardium is of conical form, having its apex above the base of the heart, and its base attached to the central tendon of the diaphragm below the apex of the heart. The inferior vena cava pierces the pericardium through the central tendon of the diaphragm, and receives no covering from the external layer of the pericardium. The right side of the heart is the venous side, receiving into its auricle from the coronary sinus and venae cavae (the superior and infe- rior vena cava) the dark, venous blood from the entire body. From the right auricle the blood passes through what is called the “ auriculo-ven- tricular orifice ” (orifice connecting the auricle and ventricle) into the right ventricle; and from the right ventricle, through the pulmonary artery to the lungs. The aerated, or arterialized blood from the lungs is returned to the heart, but to the left side instead of the right, by the pulmonary veins (usually four in number), and is received by the left auricle (two veins opening on either side of the auricle). From the left auricle the blood passes through the auriculo-ventricular orifice of the left side of the heart into the left ventricle, and from the left ventricle through the aorta and its branches to the capillaries of every part of the entire body. From the capillaries the blood is returned to the heart again, by the veins, every minute or two of a person’s life, going out in the arteries and back in the veins ; and this constitutes the circulation of the blood. The auricles (little ears, or receivers) receive the blood ; the ventri- cles (little bellies, or cavities) expel it. The auricles occupy the upper portion of the heart, and the ventricles the lower portion (the apex of the heart). The auriculo-ventricular orifice on either side of the heart is guarded by a valve — the mitral on the left, and the tricuspid on the right. The venous blood passes through the tricuspid valve; the arterial blood through the mitral valve. The entrance to the pulmonary artery, and also to the aorta, is guarded by a semilunar valve. The word valve, as used by different authors, is somewhat indefinite. It may mean a fold- ing door, or one of the leaves of a folding door. It is here used in the former sense. The mitral valve (resembling the top of a bishop’s miter [head-dress]) has two leaves ; the tricuspid (three points) and semilunar (half-moon) each three leaves. ANGIOLOGY. 205 The valves are all formed by a duplicature of the lining membrane of the heart. This membrane is continuous with the lining membrane of the great blood-vessels, and is called the “ endocardium ” (within the heart). The Eustachian valve (named from Bartholomew Eustachius, who died at Rome in 1570, A. D.) is semilunar in form, has a single cres- cent-shaped fold, and is situated at the junction of the inferior vena Fig- 137- LEFT SIDE OF THE HEART AND COMMENCEMENT OF THE LARGE ARTERIES, SHOWING THE LEFT AURICLE AND VENTRICLE. cava with the right auricle. In the foetus it is large, and serves to direct the blood through the foramen ovale (oval opening) into the left auricle. In the adult it is usually small, or altogether wanting. The coronary valve protects the orifice of the coronary sinus during the contraction of the auricle. The coronary sinus (bay or gulf) returns blood from the substance or walls of the heart. The anterior cardiac veins and the venae Thebesii (veins of The- besius) open directly from the substance of the heart into the right auricle. 206 ANGIOLOGY. The free margins of the folds, or leaves that form the mitral and tricuspid valves are attached, by means of the chordae tendinae (heart- strings), either to the columnae carneae (fleshy columns), or directly to the walls of the ventricles. Behind the three leaves, or flaps of the semilunar valve that guards the entrance to the pulmonary artery, are three pouches, or dilatations, which allow the folds of the valve to retire within these recesses in the coats of the vessel, and thus give an uninterrupted course to the cur- rent of blood. These recesses are called the “ sinuses of Valsalva.” Similar recesses are provided for the three folds of the semilunar valve, at the commencement of the aorta. Fig. 138. RELATIVE POSITION OF THE VALVES OF THE HEART SEEN FROM ABOVE. Altogether, the valves of the heart are three in kind, but six in number. Including the Eustachian and coronary, which are semilunar in form, there are four semilunar valves ; there is also one mitral and one tricuspid. The mitral and the tricuspid valves guard the entrance to the ven- tricles, and prevent the return of blood into the auricles ; the semilunar valves guard the entrance of the great arteries (the pulmonary and aorta), and prevent the return of blood into the ventricles; the Eusta- chian prevents the return of blood into the inferior cava; and the cor- onary prevents the return of blood into the coronary sinus, which forms the entrance of the great cardiac and posterior cardiac veins. The veins of Thebesiujs are also called venae cordis minimae (small- est veins of the heart). (“ Cor,” genitive, “cordis,” is the Latin for heart, and “cardium” is the Greek term). The auricles receive the blood through three or more openings, ANGIOLOGY 207 and transmit it by a single opening into the ventricle below. The ventricles have each two openings only,— one from the auricle on either side of the heart, and one into the great artery (the pulmonary, on the right side of the heart, and the aorta, on the left). The right auricle has more numerous openings than the left. The latter has the openings from the pulmonary veins (usually four, but may be three or five), and an opening through the mitral valve into the left ventricle. The right auricle has three large openings,— two from the venae cavae (two largest veins in the body), and one through the tricuspid valve into the right ventricle, and several smaller openings for the coronary sinus and venae cordis minimae (smallest veins of the heart). The fossa ovalis (oval depression) marks the situation of the fora- men ovale (oval opening) in the foetus (the unborn child ; pronounced fetus). It is situated at the lower part of the muscular septum, between the auricles and above the orifice of the inferior vena cava. In many cases a small, slit-like opening exists between the auricles of the adult, showing an imperfect closure of the foramen ovale. The tuberculum Loweri (tubercle of Lower) and the musculi pec- tinati (comb-teeth muscles) of authors are of minor importance, so far as relates to an understanding of the circulation. The heartstrings (chordae tendinae) are the stays of the tricuspid and mitral valves, and prevent the leaves or segments of the valves from being carried or pushed back into the auricles. The cavity of the right auricle, when moderately distended, con- tains 59 c c. (about two ounces) of blood: (c.c. is the abbreviation for cubic centimeter. It is a cube whose side is one hundredth of a meter. The meter is almost 40 inches, or, more exactly, 39-37). The left auricle is a little smaller than the right. The superior vena cava, returning the blood from the upper half of the body, opens into the upper and front part of the right auricle; while the inferior vena cava opens into the lowest part of the same cavity. The right ventricle extends from the right auricle to the apex of the heart (minus the thickness of its walls), and forms the larger part of the front of the heart. Its under surface rests upon the diaphragm. At its upper part the right ventricle has a conical prolongation, called the “infundibulum” (funnel-shaped), or “conus arteriosus” (arterial cone), from which arises the pulmonary artery. The left ventricle is longer than the right, and its walls are thicker, but it contains about the same quantity of blood. It forms a consid- erable portion of the posterior surface, and a small part of the left side of the anterior surface of the heart. The muscular fibers of the auri- cles and those of the ventricles are quite independent of each other. 208 ANGIOLOGY. The nerves of the heart belong to both the spinal and sympathetic system. The heart is also furnished with ganglia (nerve centers). The arteries alzvays carry blood from the ventricles of the heart; the veins carry blood toward the auricles of the heart. The arteries generally carry arterial blood, and the veins venous blood ; but to this there are two exceptions,—one in the pulmonic circulation of the adult, the other in the foetal circulation. The pulmonary artery of the adult, and the umbilical, or hypogastric arteries of the foetus, carry venous blood ; while the pulmonary veins of the adult and the umbilical vein of the foetus carry arterial blood. All the arteries of the body are branches of either the pulmonary artery or of the aorta, these being the only vessels that carry blood directly from the ventricles of the heart. The names of arteries generally indicate prominent parts to which they are distributed, or parts and organs which they supply with blood. The same is true of the veins ; their names generally indicate the parts from which they return blood to, or toward, one of the auricles of the heart. Blood-vessels (arteries and veins) are found in all parts of the sys- tem, except the hair, nails, epidermis, cartilage, and the cornea (ante- rior covering) of the eye. A very minute artery takes the name of arteriole. The arterioles join the capillaries. The large blood-vessels are generally deep-seated, and well protected from injury. As a rule, the large vessels are straight; but where provision is needed for the extension of the part, the vessels are tortuous, that they may not restrict the movement. The internal carotids, the facial, and the ver- tebral arteries are examples of tortuous vessels. The smaller arteries and veins communicate freely with each other by what is termed anastomosis, or inosculation. Both words have the same meaning'—one being derived from the Greek and the other from the Latin. Either term signifies that two or more vessels com- municate with each other, so that when the blood is obstructed or arrested in one vessel it can proceed along other vessels, and thus reach parts beyond the obstruction. The circulation through such unusual channels is called ‘‘collateral circulation.” In some instances large arteries communicate (inosculate) with each other. The circle of Willis in the brain, and the arteries of the mesentery, hand, and foot, are examples of inosculation of large arteries. The arteries and veins all inosculate in the capillaries of the system. The arteries and veins have three coats,— internal, middle, and external. The internal coat is epithelial; the middle, elastic, and more or less muscular ; and the external coat cellular, or connective. The ANGIOLOGY. 209 external coat is firmer than the two inner, so that a ligature may be applied with sufficient pressure to divide one or both of the other coats without injury to the external coat. In the largest arteries the middle coat is very thick, and highly elastic, but becomes thinner as the ves- sels decrease in size. The walls of the blood-vessels (arteries and veins) are themselves supplied with blood-vessels, like other organs. These nutrient vessels are called vasa vasorum (vessels of vessels). They arise from a branch of the same vessel, or from a neighboring vessel. The vaso-motor (vessel-moving) nerves are derived chiefly from the sympathetic, but partly from the cerebro-spinal system, or, at least, are intimately connected with the latter. The larger arteries and veins are surrounded by a prolongation of fascia, which forms a sheath for them. The sheath usually incloses the accompanying vein or veins, and sometimes a nerve. The capillaries are minute microscopic tubes, situated between the arteries and veins, which they serve to connect. Their usual diameter is .008 mm. (tAu of a millimeter = 3 As of an inch). The smallest capillaries are those of the brain. The number of the capillaries and the size of the interspaces determine the degree of vascularity of a part. The closest network is found in the lungs. As a general rule, the more active the function of an organ the closer is the capillary network, and the larger the supply of blood. The network is narrow in the glands and mucous membranes; wider in bones and ligaments, which are comparatively inactive, and nearly or quite absent in tendons and cartilage, in which little change occurs after their formation. THE ARTERIES. The aorta (called also arteria magna,—“ great artery ”) is the main trunk gf all the vessels which convey red, oxygenated blood to every part of the body. The term “aorta” signifies “arising from.” It arises from the left ventricle of the heart; passes obliquely upward and forward toward the right; arches backward to the left, over the root of the left lung ; descends within the thorax, on the left of the vertebral column, or median line; passes through the diaphragm in front of the vertebral column into the abdomen, and terminates a little above the pelvis (op- posite the fourth or fifth lumbar vertebra) in two large branches,— the common iliac arteries,— which, on account of their situation at the end of the aorta, are termed terminal branches. The entire number of branches given off by the aorta during its entire course is about sixty; but they are described under nineteen. 210 ANGIOLOGY. Fig. 139- ARCH OF THE AORTA, AND ITS BRANCHES. Treads, or terms — eighteen besides the common iliac arteries,, These will be given further on. For convenience of description, the aorta is divided into parts, or portions. Those portions, contained respectively in the thorax and abdo- men, are named the “ thoracic ” and the “ abdominal ” aorta. These are subdivided. The first part of the thoracic aorta is called “the arch,” be- cause it forms a bow. Again, the arch itself is described in three seg- ments, named respectively the ascending, transverse, and descending portions. The ascending portion is about five centimeters (two inches) ANGIOLOGY. 211 long, and is contained in the cavity of the pericardium (heart-case). It gives off to the substance of the heart the coronary (or cardiac) arteries at the commencement of its course. Two other coronary arteries, branches of the facial, carry blood to the upper and lower lips. The transverse portion of the arch lies obliquely in the chest, passing backward toward the left side. It lies three or four centimeters (one or two inches) below the upper margin of the sternum (breast-bone), and is seven centimeters (about three inches) long. This portion (the transverse) of the arch usually gives off three large trunks,— the innominate, the left common carotid, and the left subclavian arteries. The descending portion of the arch passes downward along the bodies of the third and fourth dorsal verte- brae, and becomes the thoracic aorta (often so called, although all above the diaphragm is properly thoracic), which extends to the diaphragm. The abdominal aorta extends from the diaphragm to its bifurcation (division into two branches), just above the brim of the pelvis. The branches of the aorta are as follows: — 1. Coronary, i to 4 in number, usually 2—the right and left coronary. These supply the substance of the heart. 2. Innominate, or brachio-cephalic (“arm and head” on the right side). 3. Left common carotid (to the left side of the head). 4. Left subclavian (to the left upper extremity). 5. CEsophageal, 4 or 5 in number (oesophagus). 6. Pericardiac, irregular in number (heart-case). 7. Bronchial, usually 3, possibly 1 (lungs). 8. Posterior mediastinal, several small ones. 9. Aortic intercostals, 9 or 10 on either side (between the ribs). All the above are given off above the diaphragm, and the first four from the arch. Below the diaphragm (or from the abdominal aorta) we have: — 10. Inferior phrenic, 2 (below the diaphragm). 11. Coeliac axis, very soon dividing into the gastric (stomach), hepatic (liver), and splenic (spleen) arteries. 12. Superior mesenteric, 1 (small intestine and part of the large). 13. Supra-renal, 2 (supra-renal capsules). 14. Renal, 2 (kidneys). 15. Spermatic, 2 (testicles). 16. Inferior mesenteric, 1 (lower part of the large intestine). 17. Lumbar, 8 in number (loins). 18. Sacra media, 1 (“middle of the sacrum.” It supplies the pos- terior surface of the rectum, and terminates in what has been called “Luschka’s gland.”) 19. Common iliac, 2 (to the lower extremities). 212 ANGIOLOGY. The innominate artery is the largest branch given off from the arch of the aorta. It ascends four or five centimeters (about two inches), and divides into two branches,— the right common carotid and right subclavian. It is separated from the sternum in front by two muscles (sterno-hyoid and sterno-thyroid), by the remains of the thymus gland and by the left innominate vein. Occasionally the in- nominate artery is absent; in which case the right common carotid and right subclavian arise separately from the arch of the aorta, giving four instead of three large trunks from the transverse portion of the arch. The left common carotid artery arises from the highest part of the arch, near the origin of the innominate, and is longer than the right common carotid, which springs from the innominate. Within the tho- rax the left common carotid lies just in front of the trachea, oesophagus, and thoracic duct. In the neck, the two common carotids occupy, on either side, a nearly similar position. They extend upward to the upper border of the thyroid cartilage (Adam’s apple), where each bifurcates, and forms the external and internal carotid arteries. Each common carotid in the neck lies without the pharynx, larynx, and trachea, and within the internal jugular vein. The sheath of the common carotid incloses also the pneumogastric nerve and the internal jugular vein. The nerve lies between and behind the other two. The right and left subclavian arteries carry blood to the upper ex- tremities. The left subclavian is a branch of the aorta; the right, a branch of the innominate (when the innominate is present). The oesophageal arteries, four or five in number, arise from the front of the aorta, and pass obliquely downward to the oesophagus, where they anastomose with branches of the inferior thyroid, phrenic, and gastric arteries. The pericardiac arteries, irregular in number and small in size, supply the pericardium (heart-case). The bronchial arteries are the nutrient vessels of the lungs. They vary in number, from one to three. That of the right side (to the right lung) sometimes arises from the first aortic intercostal, but they may all arise from the aorta. The posterior mediastinal arteries are small vessels that supply glands and connective tissue in the mediastinum. The aortic intercostal arteries (the last to be mentioned of the thoracic branches) supply the intercostal muscles, and anastomose (com- municate) with branches of the internal mammary and axillary arteries. They are usually ten in number on each side, the upper intercostal space ANGIOLOGY. 213 being supplied by a branch of the subclavian artery. (The branch sup- plying the upper intercostal space is called the superior intercostal artery.) The phrenic arteries supply the diaphragm and some neighboring parts with blood. Fig. 140. THE CCELIAC AXIS, AND ITS BRANCHES. Those derived from the aorta are termed inferior phrenic, to dis- tinguish them from other phrenic arteries derived from the internal mammary. The inferior phrenic arteries, two in number, sometimes arise from the aorta, or coeliac axis, by a common trunk ; or one may spring from one of the renal (kidney) arteries. They diverge across the crura (legs) of the diaphragm, and pass upward and outward upon its under surface. 214 ANGIOLOGY. The cceliac (“coelum,” sky, or heavens; because the diaphragm forms an arch, or vault, over the abdomen, like the sky above the earth: hence, coeliac relates to the abdomen) axis is a short, thick trunk, about one or two centimeters (half an inch) in length, arising from the aorta in front, and, passing directly forward, divides into three branches- Fig. 141. CCELIAC AXIS AND BRANCHES IN CONNECTION WITH THE STOMACH AND SPLEEN. (gastric, hepatic, and splenic arteries), which supply the stomach,, liver, and spleen. The splenic is the largest of the three. The splenic and hepatic arteries both send branches to the stomach, also. The gastric (stomach) artery extends along the lesser curvature of the stomach from the cardiac to the pyloric orifice, and inosculates with, branches of the splenic and hepatic arteries. ANGIOLOGY. 215 The superior mesenteric (upper middle intestine) artery is a vessel of large size. It arises from the aorta, just below the coeliac axis, passes forward in front of the duodenum (small bowel just below the stomach), and descends between the layers of the mesentery (folds of peritoneum [a serous membrane that lines the abdominal cavity and in- Fig. 142. SUPERIOR MESENTERIC ARTERY, AND ITS BRANCHES. vests the bowels]) toward the right iliac fossa, giving off numerous anas- tomosing branches to the bowels. This artery (the superior mesenteric) supplies the whole length of both the small and large bowels, except a part of the small bowel near the stomach and the lower part of the large bowel. The descending colon, sigmoid flexure, and rectum, are 216 ANGIOLOGY. supplied mainly by the inferior mesenteric artery, which is smaller than the superior, and descends toward the left iliac fossa. The inferior mesenteric artery arises from the left side of the aorta, three or four centimeters (one or two inches) above its division into the common iliacs, and after supplying the descending colon and sigmoid flexure, descends into the pelvis, under the name of the superior hemorrhoidal artery, which supplies, in part, the rectum. The trunk of the latter artery divides at the middle of the sacrum, about a finger’s length from the anus, which is the limit of safety in dividing the rectum during any necessary surgical operation. Fig- *43- 1." Superior mesenteric a. 2.. C<$ca media. 3. .Colica dextra. •> 4. Ileo-colica. 5- Inferior mesenteric a., 6. Colica sinistra. 7. Arteria sigmoidea. 8. Superior haemorrhoid* al a. ANASTOMOSIS OF THE MESENTERIC ARTERIES There are two other hemorrhoid arteries (middle and inferior hem- orrhoidal), one of which is a branch of the internal iliac, and the other of the internal pudic, which is itself a branch of the internal iliac. The supra-renal arteries are two small vessels that supply the supra-renal capsules. They arise, one from each side of the aorta, opposite the superior mesenteric artery. The renal (kidney) arteries are two large trunks which arise from the sides of the aorta, just below the supra-renal arteries. The right renal is longer than the left, on account of the position of the aorta on the left of the median line, and somewhat lower, corresponding to the position of the right kidney, which is depressed by the position of the liver. Previously to entering the kidney, each artery divides into four or five branches. ANGIOLOGY. 217 The spermatic arteries supply the testes of the male, and corre- spond to the ovarian of the female. These are two slender vessels which arise from the front of the aorta, a little below the renal arteries. They pass obliquely outward and downward through the inguinal canal, along the spermatic cord, to the testes in the scrotum. The ovarian Fig. 144. INFERIOR MESENTERIC ARTERY, AND ITS BRANCHES. arteries are shorter than the spermatic, and do not pass out of the abdominal cavity, although some branches are continued along the round ligament to the labia. They supply the ovaries and oviducts. The lumbar arteries are analogous to the intercostal. They arise, four in number, on each side, from the back part of the aorta, pass out- ward and backward around the sides of the body of the corresponding 218 ANGIOLOGY. vertebra, and divide each into two branches (dorsal and abdominal). The dorsal branch of the lumbar gives off a branch that enters the spinal canal (a spinal branch), and also supplies the muscles and integ- ument of the back. The abdominal branches pass outward behind the square muscle of the loins (quadratus lumborum) to the abdominal muscles, and inosculate with branches of the epigastric, internal mam- mary, and others. The sacra media (middle sacral) artery arises from the back part of the aorta, near its bifurcation, passes in front of the last lumbar ver- tebra and sacrum, supplies the posterior surface of the rectum, and in- osculates with the two lateral sacral, which are branches of the internal iliac. The common iliac arteries are the terminal branches of the aorta. The bifurcation (division of a trunk into two branches) takes place in the umbilical region on a level with the crest of the ilium (usually opposite the left side of the fourth lumbar vertebra). The common iliac arteries extend from the bifurcation of the aorta to the brim of the pelvis, and there bifurcate, forming the internal and external iliac arte- ries— one supplying the pelvic viscera, the other the lower extremity of the body. The common iliac arteries vary in length from one to eleven centimeters (one half to four and one-half inches). They are sometimes called “primary iliacs.” They give off some small branches to the peritoneum, psoas muscles, and ureters, but none yet honored with a name. Having completed the description of the aorta and its primal branches, we shall next describe some of the more important arteries that arise from these branches, commencing with the branches of those last described (the common iliacs). The internal iliac artery (one of the two branches of the common iliac, on either side) supplies the walls and viscera of the pelvis, the genital organs, and the inner side of the thigh. It extends from the bifurcation of the common iliac artery, usually, to the upper margin of the great sacro-sciatic foramen, where it divides into two large trunks (anterior and posterior). A partially obliterated cord (the superior vesical artery), which is the part of the foetal hypogastric artery that does not become entirely obliterated after birth, extends from the internal iliac artery to the side and body of the bladder, and gives off a slender vessel that accompanies the vas deferens (“outward bearing vessel,” applied to the seminal duct that forms a part of the spermatic cord) to the testis, and inos- culates with the spermatic artery from the aorta. The “middle vesical” of authors is a branch of the superior vesical artery. ANGIOLOGY. 219 The inferior vesical (“ vesica,” bladder) artery is a branch of the internal iliac, and is distributed to the bladder, prostate gland, and seminal vesicles (vesiculae seminales). Besides the vesical arteries, the “anterior trunk ” of the internal iliac gives off four other branches in the male, and six in the female. The six branches are the middle hemorrhoidal, obturator, internal pudic, sciatic, vaginal, and uterine. The last two are peculiar to the female. The sciatic and internal pudic are the terminal (end) branches of the “anterior trunk.” The posterior trunk forms three branches,— the gluteal (which is the continuation of the posterior trunk), ilio lumbar, and lateral sacral. Altogether, the two trunks of the internal iliac artery have nine branches in the male, and eleven in the female. These branches are next described. The middle hemorrhoidal artery supplies a portion of the rectum, anastomosing (or inosculating) with the other hemor- rhoidal arteries (superior and inferior hemorrhoidal). The obturator artery passes out of the pelvis through the upper part of the obturator (“closed up,” but not entirely) foramen, and divides into an internal and external branch, and supplies with blood various muscles of the thigh. Within the pelvis the obturator artery gives off an iliac branch to the iliac muscle, a vesical branch to the bladder, and a pubic branch, which ascends upon the back, or inner side, of the pubes, and communicates with branches of the epigastric. The pubic branch of the obturator is placed on the inner side of the femoral ring. The internal pudic artery supplies the external organs of generation. Its terminal branches in the male are the dorsal artery of the penis, and the artery of the corpus cavernosum (“spongy body,” or body filled with cavities). In the female the two terminal branches supply the clitoris. In the perineum (floor of the pelvis) the internal pudic gives off, in addition to those already mentioned, four other branches (artery of the bulb, which supplies the bulb of the urethra and Cowper’s gland ; inferior hemorrhoidal, which supplies muscles and integument of the anal region; and two perineal — superficial and transverse). The artery of the bulb is very liable to be severed in the lateral operation of lithotomy (“cutting for stone” in the bladder). When severed it gives rise to alarming hemorrhage (bleeding). The sciatic artery distributes blood to muscles on the back of the pelvis. It escapes from the pelvis through the great sacro-sciatic fo- ramen, between the pyriform and coccygeus muscles. Within the pel- vis it supplies branches to the muscles just named, to the rectum, neck of the bladder, and prostate gland. External to the pelvis it gives off five branches; viz., the coccygeal, to the back of the coccyx, the infe- 220 ANGIOLOGY. rior gluteal, the comes nervi ischiatici (companion of the sciatic nerve), the muscular, and the articular. The latter supplies the capsule of the hip joint. The companion of the sciatic nerve accompanies the nerve for a short distance, then penetrates it, and runs in its substance to the lower part of the thigh. The vaginal artery supplies the mucous membrane of the vagina, and some branches to the neck of the bladder. The uterine artery, together with the ovarian from the aorta, sup- plies the uterus. The gluteal artery is the largest branch of the internal iliac, but soon divides into a superficial and deep branch. It supplies muscles in and about the pelvis and hip joint. The ilio-lumbar artery ascends to the upper part of the iliac fossa, and divides into two branches (lumbar and iliac). The lateral sacral arteries are usually two in number on each side,— superior and inferior. This completes the branches of the internal iliac. The external iliac artery is the chief vessel of supply to the lower limb. It extends from the common iliac artery obliquely downward and outward, along the inner border of the psoas muscle to Poupart’s ligament (called also “femoral arch ”), beneath which it passes to enter the thigh, where it becomes the femoral (thigh) artery. Its principal branches are the deep epigastric and the circumflex iliac. A knowl- edge of the deep epigastric (Gray calls this artery the “ epigastric ” sim- ply, but there are two other epigastric arteries [the siiperficial, from the femoral artery, and the superior epigastric, from the internal mammary], and it is well to distinguish them) artery is important in operations for strangulated hernia. The deep epigastric arises from the front of the external iliac near Poupart’s ligament, and ascends in the wall of the abdomen between the peritoneum and transversalis fascia, or, we may say, between the peritoneum and abdominal muscles, obliquely upward and inward to the border of the rectus muscle near its lower third, then directly upward behind the muscle till it anastomoses with the branches of the internal mammary and intercostal arteries. As it ascends, it lies behind the inguinal canal to the inner side of the internal abdominal ring (upper orifice of the inguinal canal) and immediately above the femoral ring (upper opening of the femoral canal. The femoral canal is the narrow space between the femoral vein and the inner wall of the crural, or femoral sheath. “Crural” and “femoral” are used inter- changeably). The deep epigastric artery varies in its point of origin, from several centimeters (one or two inches) above Poupart’s liga- ment to some point below. It also varies in its mode of origin. It is accompanied by two veins, which usually unite before reaching the external iliac vein. ANGIOLOGY. 221 The circumflex iliac artery arises from the external iliac, near the origin of the deep epigastric, runs along the inner surface of the crest of the ilium to its middle part, where it pierces the inner muscle (trans- verse) of the abdomen, and supplies both it and the middle abdominal muscle (the internal oblique), and inosculates with the lumbar and epi- gastric arteries. The femoral artery is the continuation of the external iliac (called external to distinguish it from the internal iliac: both are within the abdomen). The femoral artery extends from its origin beneath Pou- part’s ligament at its middle part, downward through the upper two Fig- M5- INTERNAL VIEW OF THE FEMORAL AND INTERNAL ABDOMINAL RINGS — RIGHT SIDE. thirds of the thigh to the opening in the adductor magnus muscle, where it takes the name of the popliteal artery. Popliteal, femoral, and external iliac are the names of the three portions of the same vessel which extends from the common iliac within the abdomen to the tibial arteries, about five centimeters (two inches) below the knee- joint. At the upper part of the thigh, where the femoral artery emerges from beneath Poupart’s ligament, this large vessel is very superficial, and is contained in a triangular space, called “ Scarpa’s triangle.” Poupart’s ligament forms the base, or upper border of this triangle, and the border of two muscles (sartorius and adductor longus) forms its sides. This triangle is divided into two nearly equal parts by the 222 ANGIOLOGY. femoral vessels (femoral artery and femoral vein), which extend from the middle of its base to its apex below. The femoral vein lies on the inner side of the artery, and the anterior crural nerve on the outer side, but separated by the psoas muscle from the artery; or, we may say, more briefly, that the femoral artery lies between the vein and nerve ; or, again, between the vein and psoas magnus muscle. In this space (Scarpa’s triangle) the femoral artery gives off its cutaneous and deep (the profunda femoris) branches, and the femoral vein receives the deep femoral (profunda femoris) and the internal saphenous vein. The femoral artery and vein are inclosed in the same sheath, but sep- arated from each other by a thin, fibrous partition. Fig. 146. 1. Sartorius. 2. Adductor.longus. 3. External cutaneous n. 4. Iliacus internus. 5. Anterior crural n. 6. Femoral artery. 7- Femoral vein; 8- Pcctincus. 9. Long saphenous n. Jo. Internal- Cutaneous7 n. 11. Ncrvttcrvastus in-/. ternus. 12. Middle- ciitancoiJjr n. SCARPA’S TRIANGLE ; ITS BORDERS AND CONTENTS The femoral artery, the popliteal, and the posterior tibial, give off, ■each, seven branches. In each upper extremity we also have three arteries (axillary, brachial, and ulnar), which give off, each, seven branches. It should not be understood that these arteries never give off more than seven branches, but only seven with anatomical names. Some- times a single name includes several branches; as, for instance, the “muscular,” which is given as a branch of the femoral artery, is a common name for several vessels that supply chiefly the sartorius and vastus internus muscles. The other branches of the femoral artery are the anastomotica magna (great anastomosing artery) ; the profunda Fig. 147. THE FEMORAL ARTERY. 224 ANGIOLOGY. (“deep”); the superficial, and the deep external pudic ; the super- ficial circumflex iliac; and the superficial epigastric. The profunda femoris (deep femoral) is nearly as large as the vessel (femoral artery proper, or superficial femoral) from which it springs. It arises from the outer and back part of the femoral artery, three or four centimeters (about an inch and a half) below Poupart’s ligament, and supplies the muscles of the thigh. The popliteal artery lies in the popliteal space. The popliteal (“poples,” ham) space is a lozenge-shaped space at the back of the knee. It is bounded above by the hamstring muscles (the biceps on the outer side, and the semimembranosus, semitendinosus, gracilis, and sartorius on the inner), and below by the two heads (inner and outer) of the gastrocnemius. The space is covered over by the fascia lata and by the common integument. The floor of the popliteal space is formed by the posterior surfaces of the femur and tibia near the knee, the posterior ligament of the knee (called also ligament of Wins- low), and the popliteus m uscle which passes obliquely across the upper part of the tibia, downward and inward behind the knee. This space contains the popliteal blood-vessels, popliteal nerves, the small sciatic nerve, and the termination of the external saphenous vein. (The internal, or long saphenous vein ascends to the groin, and terminates in the femoral vein, a little below Poupart’s ligament). The popliteal lymphatic glands also lie in the popliteal space, and when enlarged by disease simulate aneurism (arterial pulsating tumor), pulsation being communicated to them from the popliteal artery. The popliteal artery lies deeply in the popliteal space, close to the bone ; and passing off from it, at right angles, are its articular (joint) branches, five in number, and designated as internal and external supe- rior, internal and external inferior, and azygos. The two remaining branches of the popliteal artery are the muscular and the cutaneous. There are four or five of the muscular branches. The azygos articular pierces the posterior ligament of the knee, and supplies the ligaments and synovial membrane in the interior of the joint. The popliteal artery is that part of the main vessel of the lower extremity which lies between the opening in the adductor magnus muscle above, and the bifurcation of the vessel at the lower border of the popliteus muscle, where it forms the anterior and posterior tibial arteries. The anterior tibial passes through an opening in the interosseous membrane (membrane which connects the contiguous borders of the tibia and fibula), and extends down the front of the leg to the ankle- joint, and becomes the dorsalis pedis (“back,” or upper side “of the Fig. 148. THE POPLITEAL, POSTERIOR TIBIAL, AND PERONEAL ARTERIES. 226 ANGIOLOGY. foot”). The posterior tibial artery extends down to the vicinity of the internal malleolus, and divides into the two plantar arteries, which sup- ply the sole of the foot. The branches of the anterior tibial, are the recurrent tibial (so called, because it runs upward from its origin to the knee), the muscular (several branches), and the internal and external malleolar arteries. The latter supply the ankle joint. The seven branches of the posterior tibial artery, are the peroneal (or fibular), muscular, nutrient, communicating, internal calcanean, and internal and external plantar. Fig. 149. THE PLANTAR ARTERIES — DEEP VIEW. The peroneal artery descends along the inner border of the fibula (perone) to the back of the ankle, to inosculate with the external mal- leolar and external plantar arteries. The muscular branches supply the soleus and deep muscles at the back of the leg. The nutrient artery of the tibia is the largest nutrient artery (artery entering the bone) in the body. It enters the tibia obliquely from above downward (its course is directed away from the knee, as is also the nutrient artery of the femur). ANGIOLOGY. 227 The communicating artery runs across the back of the tibia, near its lower end. The internal calcanean supplies parts about the heel. The plantar supply the sole of the foot. The external plantar has two sets of branches — the digital and posterior perforating. Having described the arteries of the lower extremities, we shall now return to that branch of the aorta which supplies blood to the right upper extremity and right side of the head — the innominate artery. Behind the inner (or sternal) end of the right clavicle, where it joins the sternum, the innominate artery divides into the right subclavian (under the clavicle) and right common carotid. The right subclavian supplies the right upper extremity, and ex- tends to the outer border of the first rib, where, entering the axilla (arm- pit), it is called the axillary artery, and again receives a new name (brachial), opposite the surgical neck of the humerus, where it leaves the axillary space. The same vessel continues its course to the bend of the elbow, where it bifurcates, and forms the radial and ulnar arteries. Each part (subclavian, axillary, and brachial arteries) of the vessel, which, as a whole, extends from the sternum throughout the armpit to the elbow, is described separately; and, further, the subclavian itself is divided into three portions by the inner and outer borders of the anterior scalene (scalenus anticus) muscle, behind which it passes. The first portion of the subclavian extends to the inner border of this muscle ; the second portion lies behind the muscle ; and the third portion extends from the outer border of this muscle to the end of the subclavian, at the outer border of the first rib, where it receives the name of axillary artery. Arising from the innominate instead of the arch of the aorta, like its fellow on the left, the first portion of the right subclavian differs from the first portion of the left subclavian in length, direction, and in the structures to which it bears relation. It is shorter than the same portion of the left by the whole length of the innominate, and arches upward and outward, while the left ascends almost vertically upward. It ascends slightly above the clavicle, and is covered in front by the integument, platysma myoid, the clavicular origin of the sterno-mastoid, sterno-hyoid, and sterno-thyroid muscles, and is crossed by the vertebral and internal jugular veins, and by the pneumogastric (lung and stomach), cardiac (heart), and phrenic (diaphragm) nerves. The first portion of the left subclavian artery is situated more deeply in the cavity of the chest; has the pleura and left lung in front and upon its outer side, the trachea (windpipe) upon its inner side, and the oesoph- agus and thoracic duct, both behind and upon the inner side. The 228 ANGIOLOGY. second and third portions of the subclavian arteries are precisely similar on both sides, so that one description answers for both, as in most parts of the two sides of the body. The second portion of each subclavian is short, and lies behind the anterior scalene muscle, or between it and the middle scalene muscle. It forms the highest part of the arch described by the subclavian artery. The subclavian (under or behind the clavicle) vein lies below and in front of the artery. Fig. 150. Fig. 151. THE SUBCLAVIAN ARTERY; ITS PORTIONS, BRANCHES, AND ANASTOMOSES The third portion of the subclavian artery is the most superficial, and is contained in a triangular space (the subclavian triangle) formed by the clavicle below and by the borders of the omo-hyoid and sterno- mastoid muscles above. The brachial plexus of nerves lies above, and in close contact with the artery. The subclavian gives off four branches,—the vertebral, internal ANGIOLOGY 229 mammary, thyroid axis, and superior intercostal. The other intercos- tals are given off from the aorta and internal mammary. Of the four branches given off by the subclavian, one (the superior intercostal) usually arises from the second portion of the vessel, the rest from the first portion. The vertebral arises from the upper and back part of the first portion ; the internal mammary from the under part; the thyroid axis, like the coeliac axis of the aorta, from the front part, and the superior intercostal from the lower and back part, either of the first or second portion. The vertebral artery, on either side of the neck, ascends through a foramen (the transverse) in the transverse process of each cervical vertebra, except the last (seventh), enters the cranium through the foramen magnum of the occipital bone, runs along the basilar groove in front of the medulla oblongata to the lower border of the pons Varolii (bridge of Varolius), and unites with its fellow of the opposite side to form the basilar artery. The latter extends from the posterior to the anterior border of the pons Varolii, gives off branches to the cerebellum, and divides into the two posterior cerebral arteries. These (the posterior cerebral) supply the posterior lobes of the cere- brum (upper brain), and inosculate with the middle and anterior cere- bral arteries, which are branches of the internal carotid. In the neck, the vertebral artery gives off a branch (the lateral spinal) to the spinal canal, and muscular branches to the deep muscles ; in the cranium it gives off four branches,— the posterior meningeal, which ramifies between the occipital bone and the meninges (membranes, or cover- ings of the brain), and also supplies the falx cerebelli; the anterior spinal, which descends on the front of the spinal cord, and unites with various other spinal branches, from the intercostal, lumbar, and sacral arteries, to form the anterior median ; the posterior spinal, which descends along the back part of the spinal cord, and the inferior cere- bellar, which extends to the under surface of the cerebellum (lower, or back brain). The anterior median artery extends along the anterior median fissure of the spinal cord, and sends branches to the cauda equina (nerve filaments from the lower part of the cord). The basilar artery (named from its position at the base of the skull), formed by the union of the two vertebral arteries, may properly be called an azygos artery, because it is single (lying in the median line of the body), while most of the arteries, bones, muscles, veins, and nerves are in pairs. It gives off four sets of branches (transverse, anterior cerebellar, superior cerebellar, and posterior cerebral). The cerebellar relate to the back brain, and the cerebral to the upper or front brain. The posterior cerebral are the terminal branches, and help to form the remarkable Fig. 152. ARTERIES AT THE BASE OF THE BRAIN. ANGIOLOGY. 231 anastomosis (circle of Willis) between the branches of the great arte- ries of the brain (internal carotid and vertebral.) The circle of Willis is formed, in front, by the two “anterior cere- bral” and the “anterior communicating” (the latter connects the two anterior cerebral) ; at the sides chiefly, by the “posterior communica- ting” (one on each side, connecting the internal carotid with the pos- terior cerebral) ; and behind by the two posterior cerebral arteries, which are the terminal branches of the basilar ; or, more briefly, this circle, or anastomosis, is formed by the anterior and posterior cerebral, and anterior and posterior communicating arteries. The internal ca- rotid arteries (by the length of their diameters) assist in forming the circle of Willis. By this anastomosis of the great arteries of the brain, the circulation is equalized, and provision made for its continuance so long as the basilar (formed by union of the two vertebral arteries), or either carotid is unobstructed. The internal mammary artery arises from the subclavian (near the origin of the thyroid axis), descends behind the clavicle and costal (rib) cartilages near the side of the sternum (breastbone), and at the interval between the sixth and seventh cartilages divides into the musculo- phrenic (muscles and diaphragm) and superior epigastric arteries. Besides the terminal, the internal mammary gives off six other branches or sets of vessels: the superior phrenic (or comes nervi phrenici,— companion of the phrenic nerve), mediastinal, pericardiac, sternal, anterior intercostal, and perforating. The superior phrenic artery accompanies the phrenic nerve to the diaphragm. The mediastinal branches supply parts of the space between the lungs (the mediastinum). The pericardiac and sternal branches supply the upper part of the heart-case (pericardium) and both surfaces of the sternum (breastbone). The anterior intercostal (between the ribs) inosculate with the intercostals from the aorta, and supply the intercostal and pectoral (breast) muscles, and also the mammary gland. The perforating arteries are also distributed to the mammary gland and greater pectoral muscle. During lactation these vessels are of large size. The musculo-phrenic feeds the diaphragm, and extends to the abdominal muscles. The superior epigastric descends to the rectus muscle of the abdomen, and inosculates with the deep epigastric from the external iliac. The thyroid axis is a short trunk arising from the front of the sub- 232 ANGIOLOGY. clavian artery, and dividing almost immediately into three branches,— the inferior thyroid, the suprascapular, and the transversalis colli. The inferior thyroid ascends to the under surface of the thyroid gland, and gives branches to the larynx (organ of voice), trachea (wind- pipe), oesophagus, and other parts of the neck. The suprascapular artery passes outward, across the root of the neck, to the upper border of the scapula (shoulder blade), over the trans- verse ligament to the supra-spinous muscle, and some other parts. Fig- 153- THE AXILLARY ARTERY AND ITS BRANCHES. The transversalis colli (transverse of the neck) passes transversely outward, across the upper part of the subclavian triangle, to the anterior border of the trapezius muscle. The superior intercostal artery is the fourth and last branch of the subclavian. It runs downward, like the internal mammary, and in- osculates with the first aortic intercostal. The axillary artery (in the armpit, or axillary space) is the continua- tion of the subclavian. It extends to the surgical neck of the humerus, ANGIOLOGY. 233 where it becomes the brachial. Its branches are the superior thoracic, acromial thoracic, thoracica longa (long thoracic), ala thoracica (a small branch), subscapular, anterior, and posterior circumflex. The circumflex arteries wind around the neck of the humerus. The branches of the axillary artery are distributed chiefly to the muscles of the breast, side, and arm. The thoracica longa supplies in part the mammary gland. The brachial artery extends from the neck of the humerus to the bend of the elbow, or a little below, where it divides, and forms the radial Fig- 154- THE BRACHIAL ARTERY. Fig. IS5- I’LNAR AND RADIAL ARTERIES—DEEP VIEW. ANGIOLOGY. 235 and ulnar arteries. It is superficial throughout its entire extent. At its middle part the median nerve lies upon it. It is accompanied by two veins — the venae comites of the brachial artery, which lie in close con- tact with it. These vessels lie along the inner border of the biceps muscle. Compression of the artery (in case of wounds) may be effected in almost any part of its course. Near the elbow it lies in front of the bone, but above, at its inner side. The brachial artery of Chaussier in- cludes the brachial, axillary, and subclavian of other authors. The seven Fig. 156. BRACHIAL ARTERY, WITH ITS BRANCHES AND INOSCULATIONS ABOUT THE RIGHT ELBOW. branches of the brachial artery are the superior profunda, the nutrient, inferior profunda, anastomotica magna (another of the same name is found in the thigh), muscular, radial, and ulnar. The nutrient artery supplies the shaft of the humerus. In the upper extremity, the nutrient arteries enter the bones obliquely toward the elbow; in the lower extremity, in a direction upward and downward from the knee. The nutrient arteries are sometimes called medullary arteries. Fig. 157- RADIAL AND ULNAR ARTERIES. ANGIOLOGY. 237 The superior profunda artery is accompanied by the musculo- spiral nerve ; and the inferior profunda, by the ulnar nerve. Both descend to the elbow, and supply muscles of the arm with blood. The anastomotica magna (great anastomosing) is so named on account of its junction with several other vessels near the elbow. The muscular (usually three or four branches) supply muscles of the arm. The radial artery is, in direction, the continuation of the brachial, but is not so large as the ulnar branch of the brachial. It commences Fig. 15S. SUPERFICIAL AND DEEP PALMAR ARCHES. at the bifurcation of the brachial just below the elbow, and runs along the radial side (side above the thumb) of the forearm to the wrist, and may be felt, by its pulsations, just outside the tendon of the flexor carpi radialis muscle. The radial nerve lies along the outer side of the artery in the middle third of its course, and two veins (venae comites) attend it throughout its whole extent. In the hand, the radial artery inoscu- 238 ANGIOLOGV. lates with a communicating branch from the ulnar artery, and forms the deep palmar arch. The branches of the radial, as usually given, are twelve in number, divided equally among the forearm, wrist, and hand. Those of the forearm are the radial recurrent, muscular, superficialis volae, and anterior carpal. The radial recurrent is given off near the origin of the radial, and runs upward to the elbow. The muscular branches are distributed to the muscles on the radial side of the forearm. The superficialis volae (superficial of the hollow of the hand) supplies muscles of the thumb, and assists in forming the superficial palmar arch. The anterior carpal supplies in part the wrist joint. The pos- terior carpal is one of the wrist group, but those of the wrist and hand are comparatively unimportant. Really, the radial artery has in all about eighteen branches. The ulnar artery crosses obliquely the inner side of the forearm to its middle, then runs along its ulnar border (the side above the little finger) to the wrist, crosses the annular ligament, and curving across the palm toward the ball of the thumb, forms the superficial palmar arch, by inosculating with a branch (the superficialis volae) of the radial artery. The seven branches of the ulnar are the anterior and posterior ulnar recurrent; the anterior and posterior carpal; the interosseous; the deep, or communicating ; and the digital. The digital branches are four in number, and are given off from the convexity of the superficial palmar arch. Gray mentions, also, muscular branches for the muscles of the ulnar side of the forearm We have now named and described the principal branches of the aorta, and also the arteries of the upper and lower extremities. There remain to be described the external and internal carotid arteries and their principal branches. The carotid arteries, one on each side, carry blood to the head ; the internal supplying parts mostly within the cra- nium, and the external parts without. The word “carotid” is of Greek origin, and is nearly equivalent in signification to the word “narcotic.” It signifies something that stupefies. Some other word, might, per- haps, be more appropriate; but we accept it because so well estab- lished, and may be reminded that impure blood flowing through these arteries stupefies the mind. The external carotid artery extends from the bifurcation of the common carotid at the upper border of the thyroid cartilage (Adam’s apple) to a point just behind the neck of the condyle of the lower jaw, where it divides into the temporal and internal maxillary arteries. Besides these terminal branches, the external carotid gives off six other branches, in order, from below, upward, as follows: ascending pharyngeal, superior thyroid, lingual, occipital, facial, and posterior ANGIOLOGY. 239 auricular. The superior thyroid, lingual, and facial are given off anteriorly, the ascending pharyngeal, occipital, and posterior auricular posteriorly. The superior thyroid occasionally arises from the com- mon carotid, but usually the common carotid has only its terminal branches. The average length of the external carotid is about eight centimeters (three inches). It is contained in the superior carotid Fig- 159- EXTERNAL CAROTID ARTERY AND BRANCHES. triangle. Of the two terminal branches, the internal maxillary is the larger. The other large branches of the external carotid are those given off anteriorly; viz., the facial, lingual, and superior thyroid. The latter supplies the upper part of the thyroid gland, and also the sterno-cleido-mastoid, and hyoid muscles, and parts of the larynx. It 240 ANGIOLOUY. inosculates with its fellow of the opposite side and with the inferior thyroid from the thyroid axis of the subclavian. The lingual artery supplies the tongue, and at its tip, on the under side, becomes the ranine. The facial artery passes upward and forward to the submaxillary gland, in which it lies imbeded, crosses the body of the lower jaw, Fig. 160. ARTERIES OF THE FACE AND SCALP. where it is easily compressed, ascends across the cheek to the angle of the mouth, then passes upward along the side of the nose to termi- nate at the inner canthus (angle) of the eye under the name of the angular artery. The latter passes along the inner border of the orbit. The facial artery gives off ten (branches and sets of) branches to the lips, tonsil, nose, etc., and anastomoses with six. Through the ophthalmic ANGIOLOGY. 241 branch of the internal carotid the facial artery serves to connect the internal with the external carotid. The superior and inferior coronary arteries are branches of the facial. The latter run to the lips. The occipital artery arises from the external carotid opposite the facial, ascends obliquely upward and backward behind the mastoid pro- cess of the temporal bone to the back part of the occipital bone, which it ascends in a tortuous course toward the vertex of the head. Fig. 161. 1. External Carotid. 2. Lingual. 3. Facial. 4. Inferior Labial. 5- Inferior Coronary. 6. Superior Coronary. BRANCHES OK THE EXTERNAL CAROTID ARTERY. 7. Lateral Nasal. 8. Angular. 9. Superior Thyroid. 10 and 16. Occipital. 11. Posterior Auricular. 12. Anterior Auricular. 13. Internal Maxillary. 14. Transverse Facial. 15. Middle Temporal. 17. Anterior Temporal. 18. Posterior Temporal. 19. Supraorbital. 20. Frontal. The posterior auricular artery runs obliquely upward and back- ward behind the ear, dividing into the stylo-mastoid and the auricidar. The ascending pharyngeal artery is the smallest branch of the external carotid. It is a long, slender vessel extending from its origin in the lower part of the external carotid almost directly upward to the 242 ANGIOLOGY. Fig. 162. EXTERNAL AND COMMON CAROTID ARTERIES. base of the brain. It gives off three sets of branches,— the external, or muscular; the internal, or pharyngeal; and the vertical, or menin- geal. The latter enter the cavity of the cranium through different foramina, and are distributed to the dura mater (outer membranous covering of the brain). One meningeal branch enters by the jugular foramen, and another by the foramen lacerum medium. ANGIOLOGY. 243 The temporal artery appears, from its direction, to be a continua- tion of the external carotid. It takes its origin with the internal max- illary artery while imbedded in the substance of the parotid gland, and does not become superficial till it reaches the root of the zygoma, which it crosses almost vertically, and five centimeters (about two inches) above, divides into the anterior and posterior temporal; the anterior passing forward to inosculate with the supraorbital and frontal arteries ; and the posterior running upward and backward to inosculate with the occipital and its fellow on the opposite side. The internal maxillary artery is the large, deep, terminal branch of the external carotid. At its origin in the substance of the parotid gland it is on a level with the lower extremity of the lobe of the ear (auricle). At first it passes horizontally forward and inward at the inner side of the ramus of the jaw, then obliquely upward toward the superior maxillary bone, and, beneath the body of the sphenoid bone, gives off its terminal branches. It gives a “ tympanic ” branch to the tympanum (middle ear); a “ middle meningeal” branch to the dura mater and cranium, through the foramen spinosum (a sphenoidal fora- men) ; a “ small meningeal” branch through the foramen ovale (another sphenoidal foramen); an “ inferior dental” branch to the inferior dental canal; the “deep temporal“pterygoid'' “masseteric,” and “buccal,” to the muscles of mastication ; an “alveolar” branch to the gums and antrum ; an “ infra-orbital” to that canal, in company with the superior maxillary nerve; a 11 posterior palatine” through that canal to the hard palate and gums; a “ Vidian” branch through the Vidian canal to the Eustachian tube, pharynx, and tympanum ; a “pterygo-palatine” to the pharynx and Eustachian tube; and a “spheno-palatine” to the mucous membrane of the nose, sphenoidal, and ethmoidal cells,—making in all fourteen branches of the internal maxillary artery that have been traced and named. The internal carotid artery supplies the anterior part of the brain, and also the eye and its appendages. It has a common origin with the external carotid at the bifurcation of the common carotid, ascends through the upper part of the neck and carotid canal of the temporal bone, enters the cranium, and, near the anterior clinoid process of the sphenoid bone, divides into its terminal branches. In passing through the carotid canal, this blood-vessel turns almost a right angle, which tends to break the force of the current of the blood before entering the brain. This artery (the internal carotid) is usually described in four portions — the cervical (neck), the petrous (in the petrous portion of the temporal bone), the cavernous (lying near the cavernous sinus of the brain), and the cerebral. The latter forms the termination of the artery in the cerebrum. ANGIOLOGY. Fig. 163. ARTERIES OF THE NECK RIGHT SIDE. The cervical portion of the internal carotid artery passes through the superior carotid and submaxillary triangles (two of the five surgi- cal triangles of the neck), but gives off no branches. The artery is, in the lower part of its course, more superficial, then passes beneath ANGIOLOGY. 245 the parotid gland, and becomes deeply situated behind and within the external carotid. It is attended by the internal jugular vein and pneu- mogastric nerve. The petrous portion is contained in a bony canal just in front of the tympanum (drum, or middle ear), and is separated from the drum only by a thin plate of bone, through which it sends its first branch (the tympanic) to the middle ear. It is surrounded by the carotid plexus of nerves, and is separated from contact with the bony walls by a tubu- lar process (sheath) of the dura mater (membrane around the brain). The tympanic artery, from the internal carotid, anastomoses in the tym- panum with tympanic branches from the internal maxillary and stylo- mastoid arteries, which spring directly or indirectly from the external carotid; or, in other words, the middle ear is supplied by branches derived from both the internal and external carotid arteries. The cavernous portion of the internal carotid gives off several small branches and one large trunk (the ophthalmic artery). The small branches, with one exception (the anterior meningeal), take the name of arteriae receptaculi (arteries of the reservoir). They supply adjoin- ing parts of the brain and dura mater. The anterior meningeal sup- plies the dura mater of the frontal region, and anastomoses with the middle meningeal artery, which is a branch of the internal maxillary from the external carotid. The ophthalmic (relating to the eye) is the principal branch of the cavernous portion of the internal carotid. It leaves the cranium through the optic foramen (foramen opticum) in connection with the optic nerve. As it enters the orbit it lies on the outer side of the optic nerve in the direction of the lachrymal gland ; but after giving off a branch (the lachrymal artery) to that gland, it crosses the optic nerve to the inner wall of the orbit, gives off a large branch (the supra-orbi- tal), which runs forward above the globe of the eye and through the supra-orbital foramen, then continues horizontally forward to the inner angle of the eye, and terminates in two branches — the frontal and nasal arteries. Altogether, the ophthalmic artery gives off twelve branches. They are usually divided into two groups — the orbital, which supply parts within the orbit but around the eyeball, and the ocidar, which supply the muscles and globe of the eye. The orbital group includes the lachrymal, supraorbital, posterior and anterior eth- moidal (supplying, respectively, the posterior and anterior ethmoid cells and some other parts), palpebral, frontal, and nasal. The ocular group includes the muscular (frequently two, supplying the muscles of the eyeball), three ciliary (anterior, short, and long), and the arteria centralis retinae (central artery of the retina). The two largest 246 ANGIOLOGY. branches (supraorbital and lachrymal) of the ophthalmic artery (a branch of the internal carotid), anastomose with the facial from the external carotid. The supraorbital artery passes through the supraorbital foramen with a nerve and vein of the same name, to supply the muscles and in- tegument of the forehead and scalp (pericranium). The lachrymal (tear) branch, or artery supplies not only the tear gland, but also the upper eyelid and conjunctiva. The palpebral (eyelid), two branches, are given off near the pulley -of the superior oblique muscle, and run along the margins of the upper and lower lids. The frontal artery passes from the orbit at its inner angle, and anastomoses with the supraorbital upon the forehead. The nasal artery runs along the back of the nose, and supplies its entire surface with blood. The three ciliary arteries supply the ciliary processes, the iris, and the choroid coat of the eyeball. The arteria centralis retinae is a small artery with a long and in- teresting name —“ central artery of the retina.” It pierces the sheath of the optic nerve behind the eyeball, and runs forward, embedded within the nerve, to supply the retina (the inner coat of the eyeball). In the foetus a small artery runs forward through the globe of the eye to the capsule of the lens. The cerebral portion of the internal carotid artery gives off four branches — the anterior, and middle cerebral, the anterior choroid, and the posterior communicating. The anterior cerebral supplies the olfactory and optic nerves, and some other anterior parts of the cerebrum (upper, or front brain). The middle cerebral artery is the largest branch of the internal carotid, and is the direct continuation of it. It lies in the fissure of Silvius. (This fissure, named from Francis Sylvius, divides the anterior and middle lobes of the cerebrum on either side, and also at the base of the brain.) The “posterior communicating,’’ on either side, runs backward from the internal carotid to reach the posterior cerebral from the basilar and vertebral arteries, and thus completes the “circle of Willis.” The anterior choroid (“skin-like,” in respect to vascularity, or great number of blood-vessels) enters the descending horn of the lateral ventricle, and is distributed to the choroid plexus and other parts in the floor of the lateral ventricle. The posterior choroid artery is a branch of the posterior cerebral from the basilar artery. The latter is formed by the union of the two vertebral at the base of the brain. The verte- ANGIOLOGY. 247 bral are the largest branches of the subclavian, and the subclavian come directly or indirectly from the arch of the aorta; directly, on the left side, and indirectly through the “ innominate,” on the right side of the body. The choroid plexus is a membranous fold of the pia mater (“soft mother, or nourisher,”—the inner of the membranes that envelop the brain), and is situated in the lateral, third, and fourth ventricles of the brain. THE VEINS. The veins return the blood from the capillaries of the body to, or toward, one of the auricles (little ears, or receivers) of the heart. The pulmonary veins, usually four in number, return the arterial blood from the lungs to the left auricle of the heart. The systemic veins, innumerable in number, but terminating, with the exception of those from the substance of the heart, in two large trunks (upper and lower vena cava), return the venous blood from the capillaries of the whole system to the right auricle of the heart. The portal vein (vena portae) returns the venous blood from the digestive organs to the liver, where it undergoes a change before it reaches the heart through the hepatic (liver) veins and inferior vena cava. The veins are larger, more numerous, and contain more valves than the arteries. They communicate freely with one another by frequent anastomoses, both large and small branches. There are three sets of veins,— the superficial, the deep, and the sinuses. The superficial veins are subcutaneous (just beneath the skin), and communicate with the deep veins by perforating the deep fasciae. The deep veins usually accompany the arteries, often in the same sheath, and are called “venae comites” (attending veins). The venae comites bear the name of the artery which they attend. The hepatic veins and some others do not accompany arteries. The brach- ial, radial, tibial, and some other arteries, have each two accompanying veins. The larger arteries have usually only one accompanying vein. The sinuses are venous channels of the encephalon (within the head), formed by division of the layers of the dura mater (outer and firm membrane that covers the brain). The walls of the veins, like the arteries, are more or less supplied with elastic and muscular tissue. Most of them have an internal epithelial lining; but the epithelium (membrane of flattened cells, or scales) becomes lost as the veins approach the capillaries. In the veins of the lower extremities valves are very numerous. The valves 248 ANGIOLOGY. Fig. 164. PORTAL VEIN AND ITS BRANCHES. (The liver and stomach are here represented as turned upward, for the purpose of showing the portal vein.) prevent the return of blood unless the veins are too much distended. The cardiac veins (sometimes called coronary) return blood from the substance of the heart directly into the right auricle. All other veins terminate finally in either the upper or lower vena cava (hollow vein). The venae cavse (plural of vena cava) are the largest veins, or ANGIOLOGY. 249 Fig. 165. SINUSES AT T1IE BASE OF THE SKULL. venous trunks, in the body. They open into the right auricle of the heart. The length of the superior vena cava is only about seven centi- meters (three inches) ; the inferior about twenty centimeters (eight inches). The superior vena cava terminates at the upper and front Fig. 166. The brachio-cephalic (arm and head) veins are commonly called the innominate (nameless) veins. SUPERIOR VENA CAVA AND ITS TRIBUTARIES. 250 ANGIOLOGY. part of the auricle ; the inferior at the lower and back part of the same auricle. There are two methods of studying the venous system. We may commence with the capillaries,— where we find millions of microscopic streams pouring into the veins blood loaded with waste matter and deprived of its oxygen,— or we may commence with the auricles of the heart,—where the veins, ultimately, all end,—and follow up the streams until we reach the capillaries and tissues of the body, where the blood commences its journey toward the heart. The venous blood occupies the right side of the heart, and never the left, so long as the lungs perform their office of decarbonizing (removing the carbon) and oxydizing (charging with oxygen) the blood; and the arterial blood always occupies the left side of the heart. The veins of Thebesius (venae Thebesii) are cardiac (heart) veins. The superior vena cava is formed by the junction of the two (right and left) innominate veins, and corresponds to the ascending portion of the arch of the aorta. It extends from the right auricle to the first costal (rib) cartilage on the right side. Besides the innomi- nate veins (venae innominatae) it receives the vena azygos (unpaired vein) just above the pericardium (heart-case), and also a few small veins. It has no valves. The azygos vein collects blood from the intercostal spaces, and serves as a connecting link between the upper and lower vena cava. It arises from the inferior vena cava, or one of its branches (renal, or lumbar), and terminates in the superior vena cava. The azygos vein receives nine or ten lower intercostal veins, several oesophageal, medi- astinal, and the vertebral veins, and near its termination the right bronchial vein. The azygos vein, proper, is generally designated as the “right azygos,” or “vena azygos major,” to distinguish it from two of its branches, which are called, respectively, the left lower and left upper azygos vein. The latter is sometimes wanting. The innominate veins are two large trunks, one on either side, formed by the union of the subclavian and internal jugular veins. They have no valves. The left innominate is the longer, and runs transversely across the chest in front of the large branches of the aorta, to meet its fellow to the right of the median line. The right innom- inate vein is a short vessel, not more than four centimeters (one and a half inches) long, while the left is double that length. The right extends from the sternal end of the clavicle almost vertically down- ward, and meets its fellow just below the cartilage of the first rib. Each innominate vein receives, besides the subclavian and internal ANGIOLOGY. 251 jugular, which form it, the vertebral, the internal mammary, the infe- rior thyroid, and the superior intercostal veins. The right innominate usually receives, in addition, the right lymphatic duct; but on the left side the lymphatic duct is called the “thoracic” (chest) duct, and opens into the left subclavian vein. The right lymphatic duct opens into the right innominate at its junction with the right subclavian vein, i. e., very near the right subclavian. Fig. 167. VENA AZYGOS—MAJOR AND MINOR. The bronchial veins, originating in the lung substance, terminate on the right side {i. e., the veins from the right lung) in the azygos vein ; on the left side, in the superior intercostal, which is a branch of the innominate. The subclavian vein, like the artery of the same name, is a con- 252 ANGIOLOGY. tinuation of the axillary vein, which is itself a continuation of the ba- silic, or a union of the basilic and brachial. The subclavian vein lies generally in front of the anterior scalene muscle, but sometimes behind it, with the artery of the same name. It extends from the outer margin of the first rib to the inner end of the clavicle, where it meets the internal jugular, and forms the innominate. It receives the exter- nal jugular, and also the anterior jugular. The posterior jugular is a branch of the external jugular ; so that really there are but three (anterior, external, and internal) jugular veins on each side of the neck. Occasionally there is but one anterior jugular. Fig. 168. VEINS OF THE LEFT ELBOW. The axillary vein, formed by the union of the basilic and brachial (the two venae comites of the brachial artery, which generally unite before they join the basilic), receives branches corresponding with those of the axillary artery, and, in addition, the cephalic vein. The cephalic is a superficial vein on the outer side of the arm, and formed at the elbow by the junction of the median cephalic and super- ficial radial. It received its name from the erroneous belief that it had more immediate connection with the head (v.tipa\rh pronounced keph-a-lee). The basilic (royal) vein is formed by the anterior and posterior ulnar (both superficial veins), and receives the median basilic near its origin in front of the elbow ; or, we may say, it is formed by the union of the median basilic and ulnar veins. ANGIOLOGY. 253 Along the middle of the forearm, in front, is a vein called the median, which inosculates with the superficial radial and ulnar veins, and unites, at the bend of the elbow, with the median basilic and median cephalic. The latter run obliquely across the bend of the elbow, and can be distinctly seen beneath the skin. The median cephalic and median basilic are both quite short, and were the veins usually chosen, when blood-letting was practiced, for venesection, or phlebotomy (vein cutting) for blood-letting. Both words are identical in meaning, but the first (venesection) is from the Latin, and the other from the Greek language. The external jugular vein, which opens into the subclavian, cor- responds in part to the external carotid artery; It is formed, properly, by the union of the temporal and internal maxillary veins, but is usually described as formed by the temporo-maxillary and posterior auricular. The latter may be considered a branch of the external jugular. The external jugular commences near the point where the external carotid artery ends, in the substance of the parotid (near the ear) gland, and receives the greater part of the blood from the exterior of the cranium and deep parts of the face ; or, in other words, returns blood from parts supplied by the external carotid artery. The internal jugular vein (one on each side) collects the blood from the interior of the cranium, and from some superficial parts, also, and corresponds in large degree, but not wholly, to the internal carotid artery. It is formed at the jugular foramen (or posterior lacerated) by the union of two large sinuses of the brain (the lateral and inferior petrosal sinuses), descends vertically through the neck, on the outer side of the internal and common carotid arteries, to the root of the neck, where it unites with the subclavian vein, and forms the innominate. It receives the facial, lingual, pharyngeal, superior and middle thyroid, and the occipital veins of the same side. The vertebral veins, one on each side, do not enter the cavity of the skull like the vertebral arteries, but collect the blood from exterior parts of the head and neck, and from the membranes of the spinal cord. The vertebral vein descends with the artery of the same name through the foramina (transverse) of the transverse processes of all the cervical vertebrae, except the last, and terminates at the back part of the in- nominate vein near the subclavian; while the vertebral artery is a branch of the subclavian. The veins of the brain are superficial and deep. The superficial collect blood from the substance of the brain, and terminate in the sinuses (large venous channels formed by layers of the dura mater). 254 ANGIOLOGY. The deep cerebral veins are two in number, one from each lateral ventricle. Each of the deep (the ventricular veins) is formed by the union of the choroid vein, with the “ vein of the corpus striatum ” (vena corporis striati). The latter receives veins from the corpus striatum and optic thalamus (parts of the brain). The deep cerebral enters the the straight sinus. The choroid vein runs along the outer border of the choroid plexus, and receives veins from the hippocampus major (“greater seahorse,”— an eminence of the brain at the posterior part of the lateral ventricle), the fornix (arch, or vault), and from the corpus callosum. The latter term is applied to a broad band of fibers which connect the right and left hemispheres of the cerebrum. “ Corpus callosum ” signifies “hard body.” Fig. 169. VERTICAL SECTION OF THE SKULL, SHOWING THE SINUSES OF THE DURA MATER. , The sinuses of the brain are 15 in number,— 7 upon the upper and back portions of the brain, and 8 at its base. They are the superior and the inferior longitudinal, the straight, 2 lateral, 2 occipital, 2 cav- ernous, 2 superior and 2 inferior petrosal, the circular, and the trans- verse. The last eight lie at the base of the brain. From these sinuses the blood flows chiefly through the internal jugular veins back to the heart. The veins of the neck return the blood from the head and face. As usually reckoned, they are ten in number, five on each side. Four of the five are jugular veins ; the other is the vertebral. The jugular ANGIOLOGY. 255 Fig. 170. VEINS OF THE HEAD AND NECK. veins are distinguished as internal and external, anterior and posterior. The latter is a branch of the external jugular. The word “jugular” signifies some relation to a “ yoke.” The word “cervical ” (relating to the neck) might be a more appropriate term for these veins. The veins of the head may be grouped as veins of the exterior, and veins of the interior of the cranium (or skull). The veins of the exterior of the cranium are the facial, temporal, internal maxillary, temporo-maxillary, posterior auricular, and occipital. The veins of the 256 ANGIOLOGY. interior of the cranium include the cerebral veins, and che sinuses. The latter are large channels, or reservoirs for venous blood. The sinuses terminate in the internal jugular veins. The facial vein is the direct continuation of the angular vein, and lies to the outer side of the facial artery. It joins the internal jugular vein. The angular vein is formed by the junction of the frontal and supraorbital veins. The frontal vein commences on the anterior part of the cranium, and communicates with the anterior branches of the temporal vein. The temporal vein gathers blood from the side and vertex of the skull. Its several branches unite above the zygoma, and form the trunk of the vein. The trunk receives the blood from the temporal muscle, and then descends between the external ear-passage and condyle of the jaw, enters the parotid gland, and, uniting with the internal maxillary vein, forms the temporo-maxillary. The temporo-maxillary .vein descends in the substance of the parotid gland, and, in the space between the ramus (branch) of the jaw and the sterno-cleido-mastoid muscle, receives the posterior auricular vein and forms the external jugular. Near the angle of the jaw, the temporo-maxillary vein communicates with the facial, and thus connects the internal and external jugular veins. The posterior auricular vein collects the blood from the side of the head behind the ear. The occipital vein collects the blood from the back part of the vertex of the skull, and following the course of the occipital artery ter- minates in the internal jugular. , The diploe forms the middle portion of the walls of the skull; or, as more commonly described, it is the cancellous (open, or porous) tissue between the outer and inner tables of the skull. It is chan- nelled in the adult by tortuous canals for the blood-vessels. The veins of the diploe (see Fig. 171) communicate with the meningeal veins and sinuses of the brain, and also with the veins of the pericranium (the membrane that covers the skull). Pericranium is only another name for the periosteum of the cranium. The inferior vena cava collects the blood from all parts below the diaphragm, and corresponds to the abdominal aorta. It is formed by the junction of the two common iliac veins, passes upward along the front of the spine on the right side of the aorta, through a groove on the back part of the liver where it receives the hepatic (liver) veins, perforates the tendinous center of the diaphragm and pericardium, and terminates in the lower and back part of the right auricle of the heart. It receives in its course the following veins or branches; viz., lumbar, ANGIOLOGY. 257 right spermatic, renal, supra-renal, phrenic, and hepatic veins. The left spermatic (in the female termed the ovarian) opens into the left renal vein. The lumbar veins, three or four on each side, collect blood in the region of the loins, by means of dorsal and abdominal branches, and terminate at the back part of the inferior vena cava. The two renal veins are of large size, and return the blood from the kidneys, corresponding to the branches and trunks of the renal arteries. The supra-renal vein terminates on the right side, like the right spermatic (ovarian in the female) in the vena cava, and on the left in the renal, or phrenic vein. Fig. 171. VEINS OF THE DIPLOE; SHOWN BY REMOVING THE OUTER TABLE OF SKULL. The phrenic (relating to the diaphragm) veins follow the course of the phrenic arteries. Those above the diaphragm (the superior phrenic), two in number, terminate, one (the right) at the upper part of the supe- rior vena cava, the left, in the left upper intercostal, or left internal mam- mary vein. The two inferior phrenic (below the diaphragm) terminate, like the spermatic and supra-renal veins, the right in the inferior vena cava, the left in the left renal vein. The hepatic (liver) veins, three in number, are short vessels con- veying the blood of the liver to the inferior vena cava, as it lies imbedded 258 ANGIOLOGY. on the posterior border of the liver. The liver receives blood from both the hepatic artery and the vena portae,— as the lungs receive venous blood from the pulmonary artery, and arterial from the bronchial arteries. The vena portae (“vein of the gate,” — relating to that part of the liver where the vessels enter as by a gate), or portal vein, is formed by the union of the superior mesenteric and splenic veins; but the splenic receives the inferior mesenteric, and also branches from the pancreas and stomach. The vena portae receives the gastric, a small vein from the smaller curvature of the stomach ; so that the portal system is composed chiefly of four large veins (superior and inferior mesenteric, splenic, and gastric) which collect the venous blood from the viscera of digestion. The splenic (spleen) vein is of large size. The two common iliac veins are the primal branches of the inferior vena cava; or, we may say, unite to form it. They are distinguished as the right and left common iliac. Each common iliac is formed by the union of the external and internal iliac veins, and receives, as branches, the ilio-lumbar, and sometimes the lateral sacral veins. The left com- mon iliac receives, in addition, the middle sacral, which is an azygos, or unmated vein. The internal iliac vein receives the internal pudic, the obturator, and all the venae comites (associate veins) of the branches of the internal iliac artery except the umbilical. The external iliac vein, like the artery of the same name, is a continuation of the femoral (thigh) vein ; the line of demarkation being formed by Poupart’s ligament (called, also, the crural, inguinal, or femoral arch). It receives immediately above this ligament the deep epigastric, and the circumflex iliac veins. The superficial epigastric, superficial circumflex iliac, and external pudic open into the internal saphenous vein near its junction with the femoral. The femoral receives the deep femoral near its termination, and the internal, or long saphenous, about four centimeters (one and a half inches) below Poupart’s ligament. The external, or short saphenous vein, opens into the popliteal vein behind the knee. The popliteal also receives the sural and articular veins. The femoral vein accompanies the femoral artery in the thigh, and, like it, becomes the popliteal vein in the popliteal space. The popliteal vein is formed by the junction of the venae comites of the tibial vessels. The posterior tibial vein is formed by the union of the external and internal plantar veins. The anterior tibial veins are formed by the continuation of the veins from the back, or upper part of the foot — the venae comites of the arteries. Saphenous signifies “manifest,” and the superficial veins of the leg and thigh were so called because they raise the skin, and manifest their course to the sight. Fig. 172. Fig. 173. LONG (FIG. 172) AND SHORT (FIG. 173) SAPHENOUS VEINS, AND THEIR BRANCHES. 260 ANGIOLOGY. The two saphenous, or superficial veins commence in a venous arch situated on the dorsum (“back,” or upper part) of the foot over the anterior extremities of the metatarsal bones. The arch is convex in front, and receives branches from the upper surface of the toes, and numerous small branches from the upper surface of the instep. The long saphenous vein commences at the inner side of the arch, passes in front of the internal malleolus along the inner side of the leg and thigh to the saphenous opening in the fascia lata, through which it dips down to join the femoral vein. It receives in its course numerous cutaneous, or superficial branches, and, near the saphenous opening, the superficial epigastric, superficial circumflex iliac, and ex- ternal pudic veins. Other large superficial veins from the back and inner part of the thigh frequently converge to join the saphenous vein near the saphenous opening. The short saphenous vein commences at the other side of the arch, and passes behind the external malleolus to the middle line of the back part of the leg, from which it receives numerous branches. It per- forates the deep fascia at the lower part of the popliteal space, and joins the popliteal vein between the two heads of the gastrocnemius muscle. It communicates with the deep veins on the back of the foot and behind the outer (or external) malleolus. SPINAL VEINS. Upon and within the spinal column are found numerous venous plexuses. Those on the exterior of the spinal column terminate by join- Fig. 174. SECTION OF A DORSAL VERTEBRA, SHOWING THE SPINAL VEINS. ANGIOLOGY. 261 Fig- 175- *• Antenor-extemak .Veins. 2. t)orsi-spinal Veins. 3. Posterior longitudinal [spinal veins. 4. Anterior longitudinal spinal veins. SPINAL VEINS. ing the vertebral veins in the neck, the intercostal veins in the thorax, the lumbar in the loins, and the sacral in the pelvis. These mostly terminate in the vena azygos (unmated vein). The latter terminates in Fig. 176. VERTICAL SECTION OF TWO DORSAL VERTEBRAS. the superior vena cava. The veins within the spinal column join the other spinal veins through the intervertebral foramina (openings between the vertebrae). LYMPHATICS. The lymphatic system consists of lymphatic vessels, including the lacteals; lymphatic ducts; and lymphatic glands, or lymph-nodes. The lymphatic vessels constitute a system of minute, delicate, transparent vessels, which have their origin in the lymph spaces, or capillary plexuses, of almost every organ in the body ; and after passing through one or more lymph-nodes, or glands, finally empty into the veins and general circulation. These vessels resemble the veins, but are smaller and more numerous. They are often called absorbents, or simply lym- phatics. They take their name from “lympha” (water), because they 262 ANGIOLOGY. generally carry a clear fluid resembling water, and called lymph ; but the lymphatics of the alimentary canal, which take the special name of lacteals (“milky vessels,” because they usually carry during digestion a milk-white fluid, or emulsion), convey the chyle (“juice” of the food) into the blood through the mesenteric glands and thoracic (chest) Fig. 177. LYMPHATIC VESSELS AND GLANDS OF THE HEAD, FACE, AND NECK. duct. The latter is the great lymphatic duct of the left side. The chyle scarcely differs from lymph, except it contains an emulsion of fatty matter not found in lymph. The lymph resembles blood in sev- eral particulars, but is destitute of color and of red corpuscles, and has a less specific gravity. Like blood, it is alkaline, of a saline taste, and when withdrawn from the vessels undergoes spontaneous coagulation. ANGIOLOGY. 263 Both chyle and lymph have white corpuscles (leucocytes), which resemble those of the blood; and in the chyle, are found immature red corpuscles. Placed in contact with oxygen, the lymph-clot, which contains white corpuscles, becomes of a scarlet-red color. On their way from the net-work of the tissues to the lymphatic ducts, which Fig. 178. DEEP LYMPHATICS AND GLANDS OF THE NECK AND CHEST. open into the veins, the lymphatic vessels pass through nodular masses, the “lymphatic glands,” which seem to have power to arrest certain poisonous substances which may find their way into the tissues, and thus prevent their entering the general circulation. These glands, or lymph-nodes, usually take the name of the part in which Fig. 179. THORACIC AND RIGHT LYMPHATIC DUCT. Fig. iSo. SUPERFICIAL LYMPHATICS AND GLANDS OF THE LOWER EXTREMITY. 266 ANGIOLOGY. they are situated, as axillary (armpit), inguinal (groin), mesenteric (mesentery), parotid (within and around the parotid gland, which is. one of the salivary glands), lumbar (loin), etc. The lacteals pass through the mesenteric glands, and finally empty their contents through the thoracic duct into the left subclavian vein. The thoracic duct commences in the abdomen, a little below the diaphragm, in a dilated portion called the receptaculum chyli (reservoir of chyle). It receives the trunks of the lacteal vessels, and also vessels from the lumbar glands, and passes through the diaphragm and chest to reach the subclavian vein, near its junction with the internal jugular. A valve guards its entrance into the vein. The thoracic duct is the Fig. 181. INGUINAL REGION, SHOWING THE SAPHENOUS OPENING, CRIBRIFORM FASCIA, SUPERFICIAL VESSELS, AND GLANDS. 1. Saphenous opening of the Fascia Lata. 2. Saphena Vein. 3. Superficial Epigastric Artery. 4. Superficial Circumflexa Ilii Artery. 5. Superficial External Pudic Artery. 6. External Abdominal Ring. 7. Fascia Lata of the Thigh. common trunk of the lymphatics of all the lower part of the body, and the left side of the upper part. Its average length is forty-two centi- meters (about sixteen and a half inches). The right lymphatic duct collects the lymph from the right side of the head, neck, right upper limb, and right side of the upper part of ANGIOLOGY. 267 the body. It opens into the vein at the angle of union between the internal jugular and right subclavian. The lymphatic vessels and glands are generally divided into superficial and deep, like the fasciae and veins, but the distinction is unimportant. The mesenteric glands number more than a hundred, and are supposed to aid in the elaboration of the chyle. They probably give birth to the white corpuscles of the blood. They are placed between the layers of the mesentery (folds of the peritoneum, which suspend the small intestine). The inguinal glands, eight or ten in number, are divisible into two groups, upper and lower. The upper group, disposed along Pou- part’s ligament, receives the lymphatic vessels from the external organs of generation and adjacent parts; while the lower group, which sur- rounds the saphenous opening in the fascia lata, receives the lymphatic vessels from the lower extremity. These glands frequently become enlarged in disease which implicates the parts in which their vessels originate. In malignant disease of the upper extremity, or of the mam- mary gland, the axillary glands are usually found enlarged, as the lymphatic vessels from those parts pass through the axillary glands. NEUROLOGY [Nerve-Study]. The nervous system of the body comprises the nerves and nerve- centers ; or, nerve-fibers and nerve-cells. The nerve-centers are termed ganglia (plural of ganglion — a knot). The nerves them- selves are composed of one or more (sometimes nearly a hundred) nerve-fibers, each fiber forming a means of communication between two parts more or less distant from each other. The greater part of nerve-matter is contained within the cranium, and is called the enceph- alon (“in the head”) —brain, or brains. The term “brain” is indefinite, and is applied to a part, or all of the encephalon. Through a great opening (foramen magnum) at the base of the cranium, the nerve- matter of the encephalon is continued down the back in a bony canal (the spinal canal), and forms the spinal cord (the “medulla spinalis,” or spinal marrow, though it differs materially from the marrow of bones). The encephalon, which is divided by the tentorium (a firm membrane stretched horizontally between the two) into the “cerebrum” (large upper and front brain) and cerebellum (small, lower, and back brain), and the spinal cord, together, make up what is called the cerebro- spinal center, or axis, from which proceed all the cranial and spinal nerves. The cranial nerves are those which leave the cranium (skull) through the openings (foramina) at its base, and the spinal nerves are those which leave the spinal canal through the openings between the vertebrae (intervertebral foramina). The cranial and spinal nerves are voluntary (under the control of the human will), and were called by Bichat (pronounced Bee-shar) nerves of animal life, in distinction from the sympathetic nerves, which he termed nerves of organic life. The latter are involuntary. Various ganglia within the body along the spinal column, but not within it, form the centers of the sympathetic nerves. These two kinds of nerves (voluntary and invol- untary, or nerves of animal and organic life) are intimately connected ; yet the nerves of animal life respond instantly and directly to the human will, while those of organic life act more slowly, and are only indirectly affected by the will. NEUROLOGY. 269 Fig. 182. CEREBROSPINAL SYSTEM OF NERVES. The encephalon (the mass of nerve-matter within the skull) includes a portion of the spinal cord,— the upper portion, called the “medulla oblongata” (oblong marrow). It is that part of the cord which lies within the cranium. The cord and encephalon are together invested by membranes (“meninges,” — Greek word for “membranes”). The outer membrane is called the dura mater (hard mother, or nour- isher), and the inner, pia mater (soft mother). A third, the arachnoid, is described, by some authors, as a serous membrane consisting of two 270 NEUROLOGY. layers, one lining the dura mater and the other covering the pia mater ; and others consider these two layers of what is called the “arachnoid” as endothelial layers belonging to the other two membranes (dura mater and pia mater). The arachnoid (spider-web form) is a colorless and transparent layer of the membrane which envelops the brain, and is separated from Fig. 183. BASE OF THE BRAIN. the dura mater that lines the skull, by what is called the sub-dural space, which contains a limited amount of fluid. The arachnoid is more or less connected with the pia mater that immediately invests the brain, and cannot be readily separated from it; but there are places where the arachnoid is separated from the subjacent layer (usually NEUROLOGY. 271 called the pia mater), and the spaces so formed are termed subarach- noid (under the arachnoid) spaces. There is one such space in the longitudinal fissure above the corpus callosum, and two of considerable size at the base of the brain. They are filled with a serous fluid (the cerebro-spinal), which communicates with the fluid of the general ven- tricular cavities of the brain, through an aperture (foramen of Magen- die) in the fourth ventricle, and also through an opening on each side, behind the glosso-pharyngeal nerves. This fluid of the subarachnoid spaces and ventricles of the brain also communicates with that of the spinal cord, and for this reason is called cerebro-spinal (brain and spinal) fluid. The membranes of the encephalon and cord are usually described separately on account of their peculiarities. The dura mater of the cord is not adherent to the bones of the spinal canal as it is to the inner surface of the skull. It does not send partitions into the fissures of the cord as in the brain ; and its laminae (plates) do not separate to form sinuses (channels for venous blood) as in the brain. The dura mater of the brain (encephalon) is a dense, fibrous membrane which lines the skull, forming the internal perios- teum. Its inner surface, next to the brain, is smooth, and covered by a layer of endothelial (“placed within”) cells, similar to those which line serous membranes. It sends three prolongations into the cavity of the skull for the support of the different parts of the brain ; two into the orbits through the sphenoidal fissures ; and forms fifteen sinuses for the passage of venous blood. It also forms sheaths for the optic and olfactory nerves. The three prolongations of the dura mater for the support of the different parts of the brain, are the two falces (plural of falx, and signi- fying “scythes,” or sickles, so named on account of their shape) and the tentorium (stretcher). The two falces are the falx cerebri (scythe of the cerebrum), and the falx cerebelli (scythe of the cerebellum). The former divides the cerebrum (upper brain) into right and left sym- metrical halves, or hemispheres; and the latter divides the right and left lobes of the cerebellum (lower or back brain). The falx cerebri occupies the longitudinal fissure between the two hemispheres of the brain, and is attached in front to the crista galli (cock’s comb) of the ethmoid bone, and behind to the upper surface of the tentorium It incloses at its upper and lower margins the superior and inferior longi- tudinal sinuses. The falx cerebelli (scythe of the cerebellum) is attached above to the under surface of the tentorium, and behind to the vertical crest (part of the crucial ridge) on the inner surface of the occipital bone. The tentorium is stretched horizontally between the 272 NEUROLOGY. cerebellum and the posterior lobes of the cerebrum. It is somewhat arched over the cerebellum. It is attached behind by its convex bor- der to the transverse portion of the crucial ridge of the occipital bone, and there incloses the lateral sinuses; in front, to the petrous portion of the temporal bones, where it incloses the superior petrosal sinuses ; and from the apex of this bone is continued forward to the clinoid proc- esses of the sphenoid bone. The tentorium and two falces being formed of the dura mater, are all firm membranes. The pia mater of the brain is a thin membrane covered exter- nally with endothelium, and containing an abundant supply of blood and lymph vessels. It invests the entire surface of the brain, dipping down between the convolutions and laminae, and projecting inward to form the lining of the ventricles. It forms the velum interpositum (inter- posed veil) and the choroid (skin-like, because vascular) plexuses. The pia mater of the cord is less vascular than that of the brain. It is also thicker and more dense in structure, and forms a sheath for Fig. 184. DIAGRAM TO SHOW THE FORMATION OF A SINUS. i. Superior Longitudinal Sinus. 2. Inferior Longitudinal Sinus. the spinal nerves. At the lower end of the spinal cord the pia mater becomes contracted, and forms a slender filament called the “ filum terminate, ” (end thread), or coccygeal ligament, which descends through the center of the mass of nerves forming the “cauda equina” (horse’s tail), and joins the dura mater below. The filum terminale retains the lower end of the cord in position, and for this reason is sometimes called the central ligament of the spinal cord. Three other ligaments connect the pia mater, which is intimately connected with the spinal cord, to the dura mater, which forms a loose sheath around the cord. These liga- ments are narrow, fibrous bands that extend longitudinally along the sides and anterior surface of the spinal cord its entire length. The anterior ligament was called by Haller (Albert Von) the linea splendens (splendid line), and those at the sides received the name of toothed liga- ments (ligamenta denticulata), on account of the points, or teeth, like those of a saw, on their outer borders, by which the ligaments are at- tached to the dura mater. By aid of the ligaments the spinal cord is NEUROLOGY. 273 made to occupy the central part of the spinal canal, and the space between the investing membranes (dura mater and pia mater) is filled by a serous secretion, known as the cerebrospinal fluid, which com- municates with the matral and ventricular cavities of the brain. (Those anatomists who describe a third membrane — the arachnoid — divide the matral space, or serous cavity that intervenes between the dura mater and pia mater, into two parts — the sub-dural and sub-araclmoid space ; and those who consider the arachnoid as a shut sack, call the serous cavity of the brain and spinal cord the arachnoid cavity.) Fig. 185. Fig. 186. SECTION OF THE SPINAL CORD. 2, 2, LIGAMENTUM DENTICULATUM. The bodies that are sometimes found upon, or beneath the dura mater of the brain, in the vicinity of the longitudinal sinus, and called glandulse Pacchioni (glands of Pacchionus), are now believed to be abnormally enlarged papillae (or villi) of the arachnoid membrane. The pressure of the circulation at these points either prevents the usual for- mation of bone over them, or wears pits, or depressions, in the inner table of the skull, much as the water wears pits, or pot-holes, in the bank, or rock, which borders it. They are not found in infancy, and rarely before the seventh year, and are said to increase as age advances. THE SPINAL CORD (Medulla Spinalis). The spinal cord is that part of the cerebro-spinal axis which is con- tained in the spinal (or vertebral) canal. It is usually about forty-two centimeters (sixteen or seventeen inches) in length, and extends from the foramen magnum (“great opening” at the base of the brain) to the second lumbar (loin) vertebra, where it terminates in a filament of gray substance, called the filum terminale (end thread), among the leash of nerves forming the cauda equina (horse-tail). In the embryo the spinal cord extends to the bottom of the sacral canal ; at birth to the third lumbar vertebra, and is relatively 274 NEUROLOGY. shortened by the growth and extension of the bones around it, or, in other words, by the thickening of the bodies of the vertebrae. It lies loosely in its canal, its investing membranes being separated from the surrounding bony walls by areolar tissue and a plexus (net- work) of veins. In form it is a flattened cylinder, enlarged in the lower part of the neck and upper part of the loins, where it gives off nerves to the upper and lower extremities. Its weight in proportion to the encephalon, or brain, is about 1 to 33. It is surrounded by, or immersed in, a fluid — the “ cerebro-spinal fluid," which, having free Fig. 187. Fig. 188. 1. Dura Mater. 2. Arachnoid Membrane. 3. Ganglion on Posterior Root of a Spinal Nerve. 4. Anterior Root of a Spinal Nerve. 5. S, Seat of Cerebro-spinal Fluid. 6. Posterior Branch of a Spinal Nerve. 7. Anterior Branch of a Spinal Nerve. SECTION OF THE SPINAL CORD. THE SPINAL CORD AND ITS MEMBRANES. passage to and from the ventricles and lymph sinuses of the encephalon, regulates and equalizes the pressure upon the nerve-centers, and pro- tects them from injury. Like the cerebrum (upper and front part of the brain and cerebro-spinal axis), the spinal cord is incompletely divided into two right and left symmetrical halves, by the anterior and posterior median fissures (or “antero-median,” and *' postero- median ” fissure). These fissures do not cut the cord entirely, since the anterior median fissure extends into the cord only about one third of its thickness, leaving a band (the commissure) of nerve-substance the entire length of the cord, which unites the right and left sides. NEUROLOGY. 275 The commissure of the cord, like the brain, is composed of two kinds of matter, gray and white. The gray matter is composed chiefly of nerve-cells, and the white of nerve-fibers. The gray matter occu- pies the central part of the commissure, and within it is a vertical canal, lined by epithelium, and called the central canal of the spinal cord. In the adult this canal can be seen, usually, only at the upper part of the cord, extending from the fourth ventricle about half an inch down the center of the cord, where it terminates in a cul-de-sac (blind alley); but prior to the sixth month of the foetus, it extends the entire length of the cord, and sometimes remains pervious throughout. Besides the anterior and posterior median fissures, which serve to divide the cord into halves, there are, on each side, three other verti- cal lines, which divide each half of the cord into four columns. The position of two of these lines is marked by the linear series of foramina, through which emerge the anterior and posterior roots of the spinal Fig. 189. SPINAL cord; its fissures and columns. nerves; and the third is marked by a slight furrow, which runs par- allel, and near to the posterior median fissure of the cord. That part of the cord which lies between the anterior and posterior roots of the spinal nerves is called the “lateral (side) column” ; the part in front of the anterior roots of the spinal nerves is called the “ anterior col- umn ; ” and the part behind the posterior roots of the spinal nerves forms the “posterior” and “posterior median” columns. The posterior median column is small, and lies adjoining the posterior median fissure. The three lines mentioned as dividing each half of the cord into four columns, all take the name of fissures, although in one case (where the anterior roots emerge) no actual fissure exists. They are named respectively the “antero-lateral,” “postero-lateral,” and “intermedi- ate ” fissures. On account of the absence of any fissure between the anterior and lateral columns of the cord, some anatomists include the 276 NEUROLOGY. anterior and lateral columns under one name — the “ antero-lateral column.” The anterior column of the cord is continuous above with the “anterior pyramid” of the medulla oblongata; the lateral column of the cord is continuous with the lateral column of the medulla; and the posterior column of the cord is continuous with the restiform (rope- form) body of the medulla above. In addition to these anatomical divisions of the spinal cord, there are others which are physiological. But before we give these latter divisions of the cord, we need to consider the gray matter which occu- pies nearly one third part of its interior. If we cut the cord trans- versely and examine the section (see Fig. 189), we find the gray matter arranged in the form of two crescents, one on each side, and Fig. 190. 1. Anterior column а. Lateral column. 3. Posterior column. 4. Posterior median column of the'spinal cord. 5. Anterior pyramid. б. Restiform body 7. Posterior pyranvd. 8. Fasciculus teres. 9. Inferior crus of the cere- helium. 10. To the corpora quadn-j gemina. 11. Crus cerebri. COURSE OF THE FIBERS THROUGH THE MEDULLA OBLONGATA. connected by a transverse band of gray matter — tho. gray commissure (the central part of the commissure of the cord), each crescent having an anterior and posterior horn. The two horns of each side extend outward from the gray commissure toward the lines (called fissures) in which emerge the anterior and posterior roots of the spinal nerves. The posterior horn is more slender, and nearly reaches the surface of the cord. The anterior horn is short and thick, and its margin has a dentate appearance. The gray matter of the cord is composed largely of nerve-cells, having from two to eight processes. These cells are of different shapes and sizes. The gray matter also contains nerve-fibers, blood- vessels, and connective tissue. The greater portion of the spinal cord, and all its exterior part, is composed of white matter, and consists largely of nerve-fibers. These fibers are mostly longitudinal, and arranged in groups forming the various columns of the cord. There NEUROLOGY. 277 are, however, in the white substance, transverse and oblique fibers. These are principally found in the commissure, the fibers passing from the anterior horn of gray matter to the anterior column of white matter on the opposite side ; from the roots of the spinal nerves to the gray matter ; and, lastly, fibers leaving the gray matter to join the longitu- dinal fibers. It is the white substance of the cord that is divided into columns. The “column of Goll ” is identical with the “posterior median col- umn,” and lies on either side of the posterior median fissure. The “ column of Burdach ’’ is the “posterior column,” and lies between the column of Goll and the posterior horn of gray matter. The col- umn of Turck is at the anterior part of the cord, and lies adjoining the anterior median fissure, on either side. It is also called the “uncrossed pyramidal tract.” The columns of Goll are small at the lower end of the cord, but become large and distinct in the cervical region. The lateral columns are divided, each, into three divisions — the anterior part of the lateral column, the direct tract (to the cerebellum), and the crossed pyramidal tract. The two latter form the posterior part of the lateral column, and the direct tract is external to the “crossed pyramidal.” Having described the spinal cord, we need not be long detained by the description of the medulla oblongata, which is really the upper part of the spinal cord, but enlarged, and somewhat peculiar. THE MEDULLA OBLONGATA. This part of the cerebro-spinal axis is situated just within the fora- men magnum (great opening), at the base of the brain. It extends along the basilar groove of the occipital bone to the lower border of the pons Varolii (“bridge of Varoli,” named from Constantio Varoli, of Bologna). The columns of the cord are continued into the medulla, but their names are somewhat changed. The anterior columns of the cord become the anterior pyramids (or corpora pyramidalia—pyrami- dal bodies) of the medulla ; the lateral column of the cord is the lateral tract (or column) of the medulla ; the posterior column becomes the restiform (rope-form) body ; and the posterior median column becomes the posterior pyramid of the medulla oblongata (so named to distin- guish it from the main portion of the spinal cord, medulla spinalis). The anterior fibers of the two anterior pyramids of the medulla, derived from the anterior columns of the cord, are continued directly upward through the pons (bridge) to the cerebrum; but the inner- most fibers, derived mainly from the deep portion (crossed pyramidal Fig. 191. Fig. 192. POSTERIOR (fig. I91) AND ANTERIOR (FIG. I92) SURFACES OF THE MEDULLA OBLONGATA. Fig. 193. CONNECTION OF THE MEDULLA WITH THE CEREBRUM AND CEREBELLUM. NEUROLOGY. 279 tract) of the lateral columns of the cord, decussate (intersect, or cross) with each other. This crossing of fibers from side to side takes place at the upper border of the atlas, or just at the entrance of the skull. The lateral tract of the medulla contains the olivary body (so named, on account of its shape). This body contains a ganglionic mass of nerve- cells, called the corpus dentatum (dentate body). A ganglion of the same name is found in the arbor vitas (tree of life) of the cere- bellum. The fibers from the lateral tract and dentate body pass upward to the cerebrum. The restiform bodies from the posterior columns of the cord, are the largest columns of the medulla. They pass upward, on either side of the fourth ventricle, and enter the cerebellum, forming its inferior peduncles (footstalks). The posterior pyramids pass upward to unite with the restiform bodies, and enter the cerebellum. The gray matter of the medulla is scattered throughout its entire substance. The medulla gives rise to all the cranial nerves except four, and is supposed to contain the nerve-centers that preside over the acts of respiration, deglutition, phonation (use of the voice), expression, and, in large degree, the circulation of the blood. For these reasons the medulla is placed in the most secure part of the head. Its dimensions, in centimeters, are about 3 in length, 1T in width, and 1 ‘ in thickness; or in inches, 1£, and | respectively. PONS VAROLII. The pons Varolii, or “tuber annulare” (annular bulb) of some authors, and the medulla oblongata, are generally considered as a part of the cerebellum, but are described separately. The pons Varolii (bridge of Varoli) lies at the center of the base of the brain, just above, and in front of the medulla. It is a bridge of nerves, which cross from the medulla below to the cerebrum above, and, transversely, from one side of the cerebellum to the other; and is composed of alternate layers of transverse and longitudinal fibers intermixed with gray matter. Its under surface projects beyond the level of these parts, and has a longi- tudinal groove, which lodges the basilar artery. Its upper surface forms part of the floor of the fourth ventricle. The cerebellum (back, or lower brain,— literally, “little, or small cerebrum”) lies in the inferior occipital fossae (lower cavities of the occipital bone), and beneath the posterior lobes of the cerebrum. Its average weight is about one ninth of the weight of the cerebrum, or a little less. The average weight of the entire brain, or encephalon, in- 280 NEUROLOGY. eluding both the cerebrum and cerebellum, is about 1,488 grams (3 pounds). The maximum weight is 2,000 grams (2 kilos, or about 4 pounds). Average weight of the cerebellum, 170 grams. Fig. 194. 1. Corpus Callosum. 2. Lateral Ventricle. 3. Third Ventricle. 4. Corpus Striatum. 5. Thalamus Opticus. TRANSVERSE VERTICAL SECTION THROUGH THE BRAIN. 6. Corpus Mammillare. 7. Choroid Plexus. 8. Fornix. 9. Pituitary Body. The surface of the cerebellum is not convoluted, like the cerebrum, but furrowed in horizontal curves. Parts on the under surface are named “uvula” and “tonsils,” or amygdalae (almonds), from their resemblance Fig- 195- CORPORA QUADRIGEMINA (DOUBLE TWINS), FOURTH VENTRICLE, AND RESTIFORM BODIES. 1. Thalamus Opticus. 2. Nates and Testes, or Corpora Quadrigemina. 3. Origin of the Fourth Nerve. 4- Process from the Cerebellum to the Testes. S'. Restiform Bodies. 6. Origin of the Auditory Nerve. NEUROLOGY. 281 to these parts of the throat. A vertical section of either hemisphere of the cerebellum reveals a foliated appearance, with a white central stem, which is called the arbor vitae (tree of life) ; and within the white sub- stance that forms the stem of the tree is a ganglion, called “ corpus dentatum ” (dentate, or toothed body). Another dentate body is found in the medulla oblongata. Fig. 196. VERTICAL SECTION OF THE CEREBELLUM (BACK BRAIN). The fourth ventricle of the brain is situated between the pons Varolii and cerebellum, and is sometimes called the “ventricle of the cerebellum.” It is lozenge-shaped, being broadest at its central part, and small above and below. It lies in a plane below the level of the base of the upper brain (cerebrum), and terminates below in the point of the “calamus scriptorius” (“writing-reed,” or pen). The point of the pen is formed by the convergence of the posterior pyramids of the medulla oblongata below. The two choroid plexuses of the fourth ventricle project into it on either side. The valve of Vieussens (pronounced Veeur-sonsse) is found in its roof. Its lining membrane is continuous with that of the third ventricle, through the “ aqueduct of Silvius,” the iter e tertio ad quartum ventriculum (way from the third to the fourth ventricle). Some authors consider the fourth ventricle and aqueduct of Silvius as a continuation of the central canal of the spinal cord of the foetus, which is thus made to extend to the third and lateral ventricles. The parts of the brain which help to connect the cerebrum, cere- bellum, and medulla oblongata, taken as a whole, are termed the meso- cephalon (middle of the head). The meso-cephalon includes the 282 NEUROLOGY. pons Varolii, the crura cerebri (legs, or footstalks of the cerebrum), the peduncles (feet) of the cerebellum, the corpora quadrigemina (four twin bodies), and the pineal gland. It was in the pineal gland (pinus,— a fir-cone, on account of its shape) that Descartes (pronounced Dacart ) placed the seat of the soul. Fig. 197. THE THIRD AND FOURTH VENTRICLES OF THE BRAIN (OR ENCEPHALON). This section of the brain shows how the surface of the brain is increased by the depth of the sulci (furrows). This body is situated between the fornix (vault) and the corpora quadrigemina. It is of reddish-gray color, and consists chiefly of nerve-cells. In dimensions it is about one centimeter (four lines, or four tenths of an inch) long, and less than that in width. At its base is a small cavity, which contains a transparent, viscid fluid, and usually some grains of earthy matter. NEUROLOGY. 283 THE CEREBRUM (Brain). The cerebrum constitutes the largest portion of the encephalon. It fills the anterior and middle fossae of the skull, and rests behind upon the tentorium. Its upper surface corresponds in general outline with the vault of the cranium, being broader behind than in front, and ovoid in form. A median longitudinal fissure divides the mass of the cere- brum into two halves, or hemispheres, right and left, and numerous other fissures divide the hemispheres into lobes and convolutions. Fig. 198. UNDER SURFACE OF THE ENCEPHALON (ENTIRE MASS OF NERVE-MATTER WITHIN THE SKULL). The mammillary bodies are also called corpora albicantia. Locus perforatus (perforated space). The longitudinal fissure, in front and behind, reaches down to the base of the cerebrum, but is interrupted in the middle by a broad, transverse commissure of nerve-fibers, which connects the two hemis- pheres, and is called the corpus callosum (hard body), or the great 284 NEUROLOGY. commissure of the cerebrum. The length of the corpus callosum from before backward, is about ten centimeters (four inches). It is arched like the upper surface of the brain, is thickest behind, and thinnest at its central part, and forms the roof of the two lateral ventricles. The fissure of Sylvius (Francis Sylvius) is one of the well-marked fissures of the cerebrum. On the under surface of the brain it sepa- Fig. 199. CONVOLUTIONS AND FISSURES OF THE OUTER SURFACE OF THE CEREBRAL HEMISPHERE. rates the anterior and middle lobes of the cerebrum ; and at the side (beneath the temporal and parietal bones) it divides the temporo-sphe- noidal from the parietal lobe. This fissure contains the middle cere- bral artery, which is the largest branch of the internal carotid. The fissure of Rolando, separates the frontal from the parietal lobe. It passes obliquely downward and forward from the upper part of the cerebrum toward the fissure of Sylvius. Another fissure, between the parietal and occipital lobes, is called the parieto-occipital fissure. NEUROLOGY. 285 These are the principal fissures of the cerebrum; and the frontal, parietal, occipital, temporo-sphenoidal, and central (or island of Reil) are the principal lobes of the hemispheres which compose the cerebrum. The frontal lobe lies in front of the fissure of Rolando, and above the fissure of Sylvius. It is subdivided into the ascending froiital (the posterior part of the frontal lobe), inferior, middle, and superior frontal. The parietal lobe is bounded by the fissure of Rolando, the parieto- occipital, and fissure of Sylvius. Fig. 200. THE LATERAL VENTRICLES OF THE BRAIN, AND, ON ONE SIDE, THE CORPUS CALLOSUM, WHICH FORMS THE ROOF OF THE VENTRICLE. The occipital lobe occupies the posterior extremity of the brain beneath the parieto-occipital fissure. It is divided by some authors into the first, second, and third occipital lobes, but more properly into superior, middle, and inferior, like the frontal lobe. The temporo-sphenoidal lobe is that portion of the hemisphere which lies at the side of the head beneath the fissure of Sylvius, and 286 NEUROLOGY. rests in the middle fossa of the base of the cranium. This is also divided by minor fissures into three smaller lobes, one above another — superior, middle, and inferior; or first, second, and third. The central lobe (or island of Reil) is situated at the base of the brain behind the frontal lobe (or, more particularly, behind the posterior orbital, which is a part of the frontal). The island of Reil is a triangular cluster of smaller convolutions (the gyri operti — covered convolutions). Fig. 201. UNDER SURFACE OF THE ANTERIOR LOBE OF THE CEREBRAL HEMISPHERE, SHOWING THE ISLAND OF REIL, ETC. On the inner surface of each hemisphere adjoining the median plane, or longitudinal sinus, the arrangement of convolutions is more simple. Taking the optic thalamus (chamber of vision), and arch of the corpus callosum (the great transverse commissure of the cere- brum) as the center of the inner surface, we find, surrounding this center, two layers of nerve-substance; and directly behind the corpus callosum, three layers. The first layer, next to the central parts just NEUROLOGY. 287 mentioned, consists of only two convolutions (gyri)—the gyrus fornicatus (arched convolution) and the gyrus uncinatus (hooked con- volution). The arched convolution surrounds the central parts on three sides (in front, above, and behind), and the other (the unci- nate) extends beneath. The gyrus fornicatus is also called the con- volution of the corpus callosum. The second, and, for the greater part of the circumference, the outer layer, is made up of three con- volutions— the marginal, quadrate, and third, or inferior temporo- sphenoidal. The marginal lies upon and in front of the gyrus Fig. 203. CONVOLUTIONS AND FISSURES OF THE INNER SURFACE OF THE CEREBRAL HEMISPHERE. fornicatus, but does not extend so far behind. It forms the mar- gin of the hemisphere on either side along the longitudinal fissure. Behind the marginal convolution is the quadrate (square) convolution, which forms the outer layer in the region of the lambdoid suture, and near the median line. The second and outer layer, below, is formed by the third, or inferior, temporo-sphenoidal gyrus. The third layer of the occipital lobe, or region, is the cuneus (wedge-like), which is wedged in between the square and the two inferior lobes, or convolu- tions. Besides the convolutions mentioned, which may be considered 288 NEUROLOGY. primary, there are numerous smaller convolutions, which make up the primary, and render their divisions somewhat obscure; but in a well- developed brain these primary convolutions may generally be recog- nized. One thing, however, must be specially noticed: the convolu- tions of the two sides are not generally symmetrical (alike on the two sides), but one side is folded differently from the other. Fig. 202. x: Corpus striatum. а. Thalamus opticus. 3. Crus cerebri. 4. Locus niger. 5. Pons Varolii, denoted by transverse lines. б. Pyramid. 7. Olive. 8. Anterior columns. 9. Lateral columns. 10. Posterior columns. 11. Corpora quadrigemina. 12. Fillet of Reil. 13. Superior crus of the cere- bellum. IA. Cerebellum. COURSE OF THE FIBERS THROUGH THE MEDULLA AND TONS. The number of convolutions and the depth of the fissures (or sulci signifying “furrows”), are determined by the extent of surface of the cerebrum: the larger the extent of surface, in proportion to the size of the skull, the more numerous the folds, or convolutions ; and, in general, the deeper the sulci. Generally the sulci are two or three centimeters (or about an inch) in depth, but vary in different brains, and in different parts of the same brain. As we descend the scale of animal life, we find the convolutions diminish in number, and finally disappear, so that we may reasonably conclude that intellect, or capacity, generally depends largely upon the extent of surface of the cerebrum. The outer surface of each convolution is composed of four, or more,. NEUROLOGY. 289 alternate layers of gray and white substance ; the white substance, which is chiefly nerve-fibers, connecting the gray nuclei, or nerve-centers, with the various parts of the body. The gray matter at the surface of the brain is called the cortex (bark, or outer part), or cortical substance. Blood-vessels penetrate the cortex of the brain in the form of small arterioles from the pia mater, and form abundant plexuses in its substance. Fig. 204. CONVOLUTIONS OF THE UPPER SURFACE OF THE BRAIN. A. Fissure of Rolando. A.F. Ascending Frontal Convolution. A.P. Ascending Parietal Convolution. S.M. Supra-marginal Convolution, below which is the Angular Gyrus. P.OParieto-occipital Fissure. F. Frontal Lobe. P. Parietal Lobe. O. Occipital Lobe. /1./2./3. Superior, Middle, and Inferior Frontal Convolutions. Pi, P2. Superior and Inferior Parietal Convolutions. Oi, O2, O3. Superior, Middle, and In- ferior Occipital Convolutions. C. m.f. Calloso-marginal Fissure. The under surface of the cerebrum, and the under surface of the entire brain (encephalon), are the same anteriorly, since the anterior and middle lobes of the cerebrum reach the base of the brain, but its posterior lobe rests upon the tentorium, above the cerebellum. At the base of the entire brain may be seen the base of the cerebellum, the medulla oblongata, the pons Varolii, the middle and anterior lobes of the cerebrum, the optic commissure, the pituitary body, the crura cerebri, the olfactory bulbs, the corpus callosum, and two fissures — the longitudinal (in front, where it reaches the base of the brain) ; and, lastly, 290 NEUROLOGY. on either side, the fissure of Sylvius. Several of these parts have been already described. The optic commissure lies in the median line at the base of the brain, and is the foiizt of junction between the two optic nerves. Fig. 205. TRANSVERSE VERTICAL SECTION OF THE BRAIN. 1. Corpus callosum in relation with the falx and the > cerebral hemispheres. 2. Ventricle of the corpus callosum. 3. Lateral Ventricles. 4. Cornu Ammonis, white externally and grey internally. 6. Cerebellum, separated from the cerebrum by the tentorium. 0. Section through the corpora quadrigemina, aqueduct of Sylvius, and pons Varolii. 7. Medulla oblongata with the vertebral arteries and the anteribr spinal branch in relation with it. 8. Auditory nerve, passing into the meatus auditorins internus. .9. Pneumogastric nerve passing through the posterior lacerated foramen. 10. Ninth nerve, passing through the anterior condyloid foramen. 11, 12. Grey and white substance of the convolutions. The fibres of the corpus callosum are shown radiating through the white to the grey substance. The pituitary (relating to mucus, or phlegm) body was named from the supposition that it was concerned in the secretion of mucus. It occupies the Turk’s seat (sella Turcica), but what particular part of the body it governs is unknown. The crura cerebri (legs of the cerebrum), or peduncles (little feet) of the cerebrum, are two thick bundles of white matter, or bundles of nerves, which extend from the cerebrum, on either side, downward and inward (converging toward the median line) to the pons Varolii. Before NEUROLOGY. 291 leaving the cerebrum, the crura, or roots of the cerebrum, pass through, on either side, two large ganglia, called the optic thalami (chambers of vision) and the corpora striata (furrowed bodies), which project from the upper and inner side of each peduncle. Above these ganglia is the great transverse commissure (the corpus callosum) of the cere- Fig. 206. SECTION OF THE BRAIN, SHOWING THE CORNUA (HORNS) OF THE LATERAL VEN- TRICLES, THE HIPPOCAMPUS MAJOR AND MINOR, THE CHOROID PLEXUS, LONGI- TUDINAL FISSURE (at THE FRONT AND BACK PARTS OF THE BRAIN), DEPTH OF THE SULCI (FURROWS), AND THE VELUM INTERPOSITUM. brum ; and the space left between the peduncles (the inter-peduncular space), and walled in by them, by the ganglia just mentioned, and by the corpus callosum above, forms the general ventricular cavity of the brain. The upper part of the ventricular cavity is subdivided by a ver- tical septum,—the septum lucidum (lucid wall),—and forms the two lateral ventricles ; and the lower undivided part of the cavity forms the 292 NEUROLOGY. third ventricle, which communicates with the lateral, on either side, above, by the foramen of Monro, and with the fourth ventricle, behind, by a way called “iter e tertio ad quartum ventriculum ” (journey from the third to the fourth ventricle), or “aqueduct of Silvius.” The fifth ventricle is the space between the two layers of the sep- tum lucidum, and can hardly be called a cavity, or ventricle, unless distended with fluid, which may occur in dropsy of the brain. We shall content ourselves by barely mentioning the names of the lamina cinerea (ashy plate), the anterior and posterior perforated space, the tuber cinereum (ashy bulb), the infundibulum (funnel-shaped), and the corpora albicantia (white bodies), all of which lie at the middle part of the base of the brain. Fig. 207. VERTICAL SECTION THROUGH THE CORPUS CALLOSUM AND PARTS BELOW. Directly beneath the corpus callosum, on either side of the septum lucidum, and formed by the upper part of the general ventricular space in the interior of the brain, are the lateral ventricles (side cavities). These are two serous cavities, one in each hemisphere, which contain more or less serous fluid. Each lateral ventricle consists of a central cavity and three smaller cavities, or cornua (horns), the anterior, middle, and posterior cornu (horn). The anterior horn curves forward and outward in the substance of the anterior lobe of the brain, or cere- brum ; the posterior horn curves backward and outward, and then NEUROLOGY. 293 inward, into the posterior lobe of the cerebrum ; and the middle horn descends into the middle lobe of the cerebrum. In the floor, or bottom, of the central cavity are found the following parts, enumerated in their order from before, backward: the corpus striatum (the plural is "cor- pora striata,” striated bodies), taenia semicircularis (semicircular rib- bon), thalamus opticus (optic chamber), choroid plexus ("skin-like net-work,” or fold of the pia mater, resembling the skin in vascularity, or multitude of vessels), corpus fimbriatum (fringed body), and fornix (arch, or vault). Fig. 208. DIAGRAM OF THE FORNIX. 1, 1. Corpora Striata. 2, 2. Thalami Optici. 2, 3. Anterior Crura of Fornix, bending down to join the Corpora Mammillaria. 4, 4. Posterior Crura of the F ornix, joining the Hippocampi. (The arrow is passed through the foramen of Monro.) 5, 5. Choroid Plexus. 6, 6. Hippocampi Majores. 7. Corpus Callosum, cut through 8. Ventricle of Septum Lucidum. On the floor of the posterior horn of the lateral ventricle is the hippocampus minor (smaller sea-horse), while the hippocampus major (larger sea-horse) extends along the floor of the middle horn of the ventricle. The hippocampus major is also called " cornu ammonis” (horn of Ammon), from its resemblance to a ram’s horn. The fornix is a longitudinal plate of white fibrous matter, situated beneath the corpus callosum (hard body). It consists of two symmet- rical halves, one for each hemisphere, joined together in the middle line, but separated from one another in front and behind, and forming the anterior and posterior crura of the fornix. The anterior crura of the fornix arch downward toward the base of the brain, separated from each other by a narrow interval. They are connected in their course with the optic commissure. The posterior crura of the fornix are intimately connected by their upper surfaces with the corpus callosum. 294 NEUROLOGY. They diverge from one another, and pass downward into the descend- ing horn of the lateral ventricle. The crura of the fornix (vault) are also called the “pillars” of the fornix. On the under surface of the fornix are some transverse lines, and others oblique, which, from a fancied resemblance to the strings of a harp, have given to this part of the brain the name of “lyra ” (harp). The Velum Interpositum (interposed veil) is a membrane reflected from the pia mater, which separates the under surface of the body of the fornix (vault) from the cavity of the third ventricle. On its under sur- face are the choroid plexuses of the third ventricle. This interposed veil covers the corpora quadrigemina, the pineal gland, and optic thalami. Fig. 209. LATERAL VENTRICLES AND VELUM INTERPOSITUM (INTERPOSED VEIL). 1. Anterior Horn. 2. Corpus Striatum. 3. Tania Semicircularis. 4. Optic Thalamus. 5. Velum Interpositum, with the Vena Galeni. 6. Lyra. 7. The posterior half of the Fornix, turned backward. 8. Hippocampus Minor. 9. Hippocampus Major. 10. Eminentia Collateralis. 11. Fifth Ventricle. 12. Choroid Plexus. The Optic Thalami (chambers of vision) are two large, oblong masses of white and gray matter that embrace the crura (roots, or footlets) of the cerebrum (upper brain). The corpora quadrigemina (four twin bodies) are also called “tubercula quadrigemina” (four twin little bulbs) and “optic lobes.” They are situated behind the third ventricle, in front of the cerebellum. NEUROLOGY. 295 and beneath the posterior border of the corpus callosum. The anterior pair are termed the “nates” (buttocks), the posterior, “testes” (witnesses). Twelve ganglia, or nerve centers, are generally enumerated as parts of the brain or encephalon. These are the cerebrum, cerebellum, medulla oblongata, 2 olfactory bulbs, 2 corpora striata, 2 optic thalami, 2 corpora quadrigemina, and the tuber annulare. These are mostly groups of nerve-centers. The average weight of the encephalon is about 50 ounces. The cranial capacity varies from 75 to 125 cubic inches. To remove the brain, the anatomist must sever or divide the scalp (including the occipito-frontalis, the aural [extrinsic, or outer muscles of the ear] and temporal muscles), the skull, or cranium, the men- inges, 12 pairs of cranial nerves with their attending vessels, 4 arterial trunks (2 internal carotid and 2 vertebral arteries), the internal jugu- lar veins and sinuses, and, lastly, the spinal cord. We have now described the cerebro-spinal axis (brain and spinal cord), with its meninges, or coverings. To complete the description of the voluntary nerves, we must describe the nerves that proceed from the brain and spinal cord ; but we shall better understand the descrip- tion of these nerves after knowing something of their structure. Each nerve of the body, so called, is a cord, or bundle of nerves, containing, sometimes, several dozen nerve-tubes or fibers, each tube forming a distinct nerve, and running a separate and independent course to its destination. Each tube, or nerve proper (for what we call a nerve is a nervous cord) contains in its center an axis cylinder, surrounded by a white substance, that isolates it from other nerves. This white substance is sometimes called the medullary sheath, or, more commonly, the “white substance of Schwann.” Around the white substance (medullary sheath) is a fine, transparent envelope, called the primitive sheath. The axis cylinder, the white substance that surrounds it, and the primitive sheath, together make up a nerve- fiber. The nerve-fibers are united in bundles, or “funiculi” (little ropes), by a tissue called neurilemma (nerve-coat), and the funiculi are all bound together in one large bundle by a sheath called the perineurium (around the nerve). The nerves do not inosculate like the blood-vessels; and however they may decussate, or form plexuses (networks) among themselves, each primitive nerve, or nerve-fiber, runs a distinct course. The afferent (bearing to, or toward) nerves carry impressions toward a nerve-center, and are generally sensory nerves ; while the efferent (bearing from) nerves carry impressions outward, and are generally motor nerves (causing motion, or action). 296 NEUROLOGY. Two kinds of nervous matter are found in the nervous system. These have already been mentioned as white and gray matter. The white matter is also called “fibrous” and “medullary” ; and the gray is often called “vesicular” (containing vesicles) and “cineritious” (ashy). The principal distinction to be remembered is the function of each. The gray matter is a nerve-center, where the nervous impression originates; while the white, fibrous matter serves to transmit impressions to distant parts. The gray matter is softer, contains more water, less albumen, and less fat, than the white ner- vous matter, and is composed of nerve-corpuscles (little bodies). Each nerve-corpuscle is a cell, or vesicle (little bladder), contain- ing a nucleus (a kernel), and within the nucleus, a nucleolus (little ker- nel). The nucleolus is sometimes peculiarly clear and brilliant. Fig. 210. DIAGRAM SHOWING THE DIRECTION OF NERVE-IMPULSES, AND ILLUS- TRATING WHAT IS USUALLY CALLED “REFLEX ACTION.” The nerve-cells, or corpuscles, vary in size and shape. In the sym- pathetic, or involuntary system, they are more nearly spherical; in the cerebro-spinal system, often stellate (like a star), or caudate (having tails, or processes). The fibrous matter is of two varieties,— the tubular and gelatinous. The latter belongs to the sympathetic system, but is often found intermingled with the tubular. The gelatinous nerve-fiber is much like the axis cylinder of the tubular-fiber deprived of its white sub- stance and sheath. It is composed of a fine, transparent material. The ganglia (knots) may be regarded as little brains, or nerve- centers, distributed in various parts of the system. They are found on the posterior root of each spinal nerve; on the posterior root of the fifth cranial nerve; on the facial (seventh cranial) nerve; the glosso-pharyngeal; the pneumogastric ; in a connected series on each NEUROLOGY. 297 side of the vertebral column, forming the double axis, or trunk, of the sympathetic system; and, lastly, upon branches of the sympathetic nerves in various parts of the body. The terminations of a nerve are distinguished as central and pe- ripheral (relating to the circumference, or outer part). The central ter- mination may be traced to the cerebro-spinal axis, or other ganglionic center. The afferent (“ bearing to,” or toward a nerve-center) nerves are also called “ centripetal” (seeking the center) nerves, and the efferent (“bearing from” the nerve-center) nerves, “centrifugal” (fleeing from the center) nerves. The centrifugal are motor nerves; the others sen- sory, or sympathetic. CRANIAL NERVES. Those nerves that have their apparent origin within the cranium are called cranial nerves. Sommering and anatomists on the continent of Europe reckon twelve pairs of cranial nerves. Willis, Gray, and some other authors include all the cranial nerves in nine pairs. The latter arrangement has reference to the mode of exit from the cranium. The seventh and eighth of Sommering leave the cranium through the internal ear-passage (meatus auditorius internus), and the ninth, tenth, and eleventh, through the jugular foramen. For this reason Willis con- sidered the seventh (facial) and eighth (auditory) as one pair ; and also the ninth (glosso-pharyngeal), tenth (penumogastric, or par vagum), and eleventh (spinal accessory) as one pair. The arrangement of Som- mering, who has twelve pairs, is much more simple, and has reference to the function of the nerves, or parts of distribution. But without choosing between these two numerical classifications, we shall avoid all confusion by avoiding the numerical designation of all cranial nerves above the sixth pair, as the first six pairs are identical in both ar- rangements. The names of the cranial nerves, in both arrangements, taken in the order in which they pass out of the cavity of the cranium, and commenc- ing in front, are as follows : — ist, Olfactory. 2d, Optic. 3d, Motor Oculi. 4th, Pathetic (or trochlear). 5th, Trifacial (or trigemini). 6th, Abducens. Fig, 21T. DIAGRAM OF THE FIRST SIX CRANIAL NERVES, WITH THEIR CHIEF BRANCHES OF DISTRIBUTION. Fl'g. 212. DIAGRAM OF THE LAST SIX CRANIAL NERVES, WITH THEIR CHIEF BRANCHES OF DISTRIBUTION. 300 NEUROLOGY. 7th, Facial (or portio dura [hard part]). 8th, Auditory (or portio mollis [soft part]). 9th, Glosso-pharyngeal. 10th, Pneumogastric (or par vagum, or simply the vagus), nth, Spinal Accessory ; and, 12th, Hypo-glossal. The 7th and 8th (facial and auditory) make up the 7th pair of Gray, and the 9th, 10th, and 1 ith (glosso-pharyngeal, pneumogastric, and spinal accessory) make up the 8th pair of Gray. The 12th (hypo-glossal) is the 9th of Gray. Gray’s enumeration is destitute of scientific basis; since the only reason for its use renders it incomplete. He includes the 7th and 8th in one pair because they leave the cranium together, or through the same opening at the base of the skull (the internal ear- passage). For a similar reason he considers the 9th, 10th, and nth as one pair. These pass out together through the jugular foramen (foramen lacerum posterius). But to be consistent, he must also reckon as one pair the 3d, 4th, 6th, and part of the 5 th, for these all pass out through the sphenoidal fissure (fordmen lacerum anterius); and he must also split up the 1 st into numerous pairs, because it leaves the cranium through numerous foramina in the cribriform (sieve-like) plate of the ethmoid bone. PLACES OF EXIT. The cranial nerves leave the cranium as follows: the olfactory nerve splits up into numerous filaments as it lies upon the cribriform plate, through which it passes by numerous foramina (openings) to enter the nasal cavities ; the optic nerve, on either side, passes through the optic foramen of the sphenoid bone; the motor oculi (mover of the eye), the pathetic, the abducens (leading from; it turns the eye outward), and the ophthalmic branch of the trifacial, all pass through the sphenoidal fissure (the “foramen lacerum anterius” of Gray) into the orbit; the superior maxillary (second division of the trifacial) passes through the foramen rotundum (round opening) of the sphenoid on either side; the inferior maxillary nerve (third division of the trifacial) passes through the foramen ovale (oval opening) of the sphenoid ; the facial and auditory nerves both enter the meatus audi- torius internus (internal ear-passage); the glosso-pharyngeal, pneumo- gastric, and spinal accessory leave the cavity of the skull through the jugular foramen (foramen lacerum posterius: the jugular foramen lies in the junction of the occipital bone with the petrous portion of the NEUROLOGY. 301 temporal) in connection with the internal jugular vein ; and, lastly, the hypo-glossal nerve passes through the anterior condyloid foramen (or foramina, as this foramen is sometimes double) of the occipital bone. OFFICE OF THE CRANIAL NERVES. The “olfactory” (smell-causing) is a nerve of “special sense,” and is distributed to the mucous membrane (schneiderian, or pituitary membrane) of the two upper passages (meatuses) of the nose. Fig. 213. OLFACTORY AND ANTERIOR PALATINE NERVES UPON THE SEPTUM OF THE NOSE. The “ optic ” (seeing) supplies the retina of the eye, and is the nerve of vision, or sight. Paralysis (diminution, or loss of power or function) of this nerve is called “ amaurosis ” (obscuration, or darken- ing), or, when slight, “ gutta serena” (“clear drop”—when floating specks are seen). The motor oculi (mover of the eye), or motores oculorum (plural of motor oculi), is a nerve of motion, and supplies five of the seven orbital muscles, and sends motor filaments to the iris (colored portion of the eye around the pupil). The pathetic (or trochlear) is a nerve of motion, and supplies the superior oblique muscle of the eye. The trifacial, or trigemini (three twins), divides into three por- tions,— the ophthalmic, superior, and inferior maxillary. The first and second portions, or branches, are sensory ; the third (the inferior max- illary) is both sensory and motor. The first branch (ophthalmic) sup- plies the conjunctiva (a delicate membrane that covers the eye in 302 NEUROLOGY. front and lines the lids), the lachrymal (tear) gland, and some other parts about the eye. The second branch (superior maxillary) supplies the upper teeth and the facial muscles of the superior maxillary region with sensation. The third branch, or portion of the trifacial (the inferior maxillary), supplies the muscles of mastication with motor power ; and the lower teeth, tongue, and lower parts of the face with sensation. The trifacial, or trigemini, is often called the fifth pair. It is the most difficult to trace of all the cranial nerves. Fig. 214. otic (Arnold’s) ganglion, and its branches to the tensor TYMPANI AND TENSOR PALATI MUSCLES. These three branches of the trifacial (three-faced, or thrice facial) make their exit from the bones of the face through three foramina (the supraorbital, infraorbital, and mental) that form a vertical line upon the face. This line runs in front of the eye and near the angle of the mouth. The supraorbital foramen is sometimes a notch, or groove, only, in the frontal bone above the orbit. The abducens (leading from) is a motor nerve, and supplies the external rectus muscle of the eyeball. The facial nerves (do not confound these with the trifacial), one on each side of the face, are nerves of motion, and supply nearly all the muscles of expression (thirty pairs and one single muscle). NEUROLOGY. 303 The auditory nerve is the nerve of hearing (one of the special senses), and supplies the internal ear (the labyrinth). The glosso-pharyngeal (tongue and throat) supplies the tongue and throat. It is in part a nerve of special sense (sense of taste), and in part a nerve of sensation. The pneumogastric and spinal acces- sory are “mixed nerves” (motor and sensory). The pneumogastric (lung and stomach nerve) supplies the organs of voice and respiration with motor and sensory fibers; and the pharynx, oesophagus, stomach, and heart with motor influence. It has a more extensive distribution than any other cranial nerve, passing down the neck through the chest and diaphragm into the abdomen. It is often called the “vagus ” (wanderer), or par vagum (wandering pair). The ‘ ‘ spinal accessory ’ ’ nerve consists of two parts : one, accessory to the pneumogastric, supplies branches to the pharynx and larynx; the other, the spinal portion, supplies the trapezius and sterno-cleido- mastoid muscles, and sends some branches to the cervical (upper spinal) nerves. The two portions have separate origins — one (the accessory portion) within, and the other (the spinal portion) without the cavity of the cranium. The spinal portion of this nerve arises from the lateral (or antero-lateral) tract, or column of the spinal cord, as low as the sixth cervical nerve; and ascending, enters the cranium through the foramen magnum, to unite with the other (accessory) portion, and pass out of the cranium with it, through the jugular foramen, in the same sheath as the pneumogastric. The hypo-glossal (under the tongue) is a nerve of motion, and sup- plies the muscles of the tongue. All the cranial nerves make their exit through openings in the base of the skull, and all, except the spinal portion of the spinal accessory, arise from the encephalon (within the head). The trunk and bulb of the olfactory nerve are really part of the encephalon, having no sheath. It sends twenty branches to the mucous membrane of the nose. The optic (seeing) nerves of the two opposite sides run obliquely backward and inward from the posterior part of the eyeballs till they meet at the optic commissure, immediately above the body of the sphenoid bone, at the base of the cerebrum. At the commissure (junction) of the optic nerves, some of the fibers turn back toward the other eye ; some cross to the other side of the brain, and continue along the optic tracts to their origin in the corpora quadrigemina; some pass from one optic tract to the other; and others are continued into the optic tract of the same side. 304 NEUROLOGY. The trifacial (fifth pair) resembles the spinal nerves, in having a. sensory root with a ganglion upon it, the “Gasserian, or semilunar.” The trifacial first appears at the under surface of the brain, at the side of the "pons Varolii,” where it consists of two fasciculi (small bundles) — an anterior and a posterior root. Like the spinal nerves, the ante- rior root is motor, the posterior, sensory. The anterior root has about twenty filaments ; the posterior, from seventy to one hundred. Fig. 215. The latter is seen at the central part of the figure, and gives off the short ciliary- nerves to the ciliary muscle and iris. NERVES OF THE ORBIT AND OPHTHALMIC, OR CILIARY GANGLION. The ganglion (“ Gasserian ”) is on the posterior root, near the apex of the petrous portion of the temporal bone. From the anterior bor- der of the ganglion are given off the three branches of the fifth pair; viz., the ophthalmic, superior, and inferior maxillary nerves. The anterior root is not connected with the ganglion, but passes beneath it and through the oval foramen of the sphenoid to unite with the inferior maxillary, and give it motor influence. Both roots originate in the gray matter of the medulla oblongata. The ophthalmic branch from the ganglion and posterior root, passes forward through the sphenoidal fissure into the orbit, and divides into the lachrymal, frontal, and nasal branches. The lach- rymal (tear) supplies the gland and conjunctiva; the frontal, the forehead and eyelids; and the nasal, the ciliary muscle and iris, the 305 NEUROLOGY. septum and tip of the nose, and the ciliary ganglion. The “frontal” branch of the ophthalmic divides within the orbit into the supratroch- lear and supraorbital branches. The “supraorbital” branch of the frontal is the direct continuation of the ophthalmic division of the fifth pair, and is the nerve that emerges upon the face above the eye. The nasal (third branch of the ophthalmic) enters the orbit with the other Fig. 216. SECOND AND THIRD DIVISIONS OF THE FIFTH CRANIAL NERVE, ITS SENSORY AND MOTOR ROOTS, THE GASSERIAN GANGLION, CHORDA TYMPANI NERVE, ANI> SUBMAXILLARY GANGLION, ETC. branches (lachrymal and frontal) of the ophthalmic through the sphe- noidal fissure, passes obliquely inward across the optic nerve, then re-enters the cavity of the cranium, and passes down by the side of the crista galli (cock’s comb) of the ethmoid into the nose. The superior maxillary (second branch of the fifth cranial) nerve extends from the Gasserian ganglion through the foramen rotundum (“round foramen” of the sphenoid bone), across the spheno-maxillary 306 NEUROLOGY. fossa (a triangular space between the sphenoid and superior maxillary bones), through the infraorbital canal just beneath the floor of the orbit, and appears upon the face below the eye, where it divides into its terminal branches (the palpebral, nasal, and labial). While in the infraorbital canal it gives off the anterior dental nerve, which enters a special canal (the anterior dental) within the upper jaw, and supplies some of the front teeth (incisors, canine, and first bicuspid). In the spheno-maxillary fossa, the superior maxillary nerve gives off Fig. 217. SPHENO-PALATINE GANGLION AND ITS BRANCHES. Spheno-palatine, near the sphenoid and palate bones. live branches (one orbital, two spheno-palatine, and two posterior dental). The orbital enters the orbit, and divides into two branches (temporal and malar). The spheno-palatine branches descend to the the ganglion of the same name. The posterior dental branches enter the substance of the upper jaw, and supply the upper molar and bicus- pid teeth, the gums, and the buccinator muscle. The palpebral branches of the superior maxillary nerve supply the orbicularis palpe- brarum (round of the lids), and the integument and conjunctiva of the lower lid. The nasal branches supply the muscles and integument of NEUROLOGY. 307 the side of the nose. The labial (lip) branches supply the integument and muscles of the upper lip and the mucous membrane of the mouth. The inferior maxillary nerve is the largest of the three divisions of the fifth cranial. It leaves the cranium through the oval foramen (foramen ovale), unites with the smaller (anterior) root of the fifth pair, and immediately beneath the base of the skull divides into two trunks (anterior and posterior). The anterior trunk gives off four branches — the masseteric, deep temporal, buccal, and pterygoid ; and the posterior trunk three branches,— the auriculo-temporal, gustatory, and inferior Fig. 218. BRANCHES OF THE INFERIOR MAXILLARY NERVE, AND THE CHORDA TYMPANI, IN CONNECTION WITH THE FACIAL NERVE. dental. The branches from the anterior trunk supply the muscles which give them name,— the masseter, temporal, buccinator, and pterygoid muscles. The auriculo-temporal branch divides into the auricular (ear) and temporal branches. The gustatory (“taste,” or lingual) nerve supplies the papillae and mucous membrane of the tongue, and the sublingual gland. The inferior dental is the largest branch of the inferior maxillary nerve. It descends from the posterior trunk of that nerve, with the in- ferior dental artery to the inferior dental foramen, where it gives off a branch (the mylo-hyoid) to the mylo-hyoid and digastric muscles; 308 NEUROLOGY. passes forward in the dental canal, beneath the teeth, giving off dental branches to the lower molar and bicuspid teeth, till it reaches the mental foramen, where it divides into two branches (mental and incisor). The mental branch emerges from the mental foramen, upon the face, and the uicisor branch continues onward within the bone to the median line, and supplies the lower incisor teeth. The mental branch supplies the depressor anguli oris, the orbicularis oris, and the quadratus menti (or depressor labii inferioris) muscles, and the integument of the lower lip. The facial nerve supplies not only the muscles of expression, but also the following: the platysma, buccinator, stylo-hyoid, posterior belly Fig. 219. BRANCHES OF THE FACIAL NERVE. 1. Branch of the Occipito-frontalis Muscle. 2. Posterior Auricular. 3. Temporal. 4. Malar. 5. Infra-orbital. 6. Buccal. 7. Supramaxillary. 8. Inframaxillary. of the digastric, and the muscles of the tympanum, and auricle. It arises from the medulla oblongata, leaves the cavity of the cranium through the internal ear-passage (meatus auditorius internus), in connection with the auditory nerve, enters the aqueduct of Fallopius (Gabriel Fallopius) at the bottom of the meatus, follows the curved course of that canal through the petrous portion of the temporal bone, and emerges at the stylo-mastoid foramen (opening between the styloid and mastoid pro- cesses) in the substance of the parotid gland, crosses the external carotid artery, and divides behind the ramus of the lower jaw into two branches (temporo-facial and cervico-facial), which send numerous branches over the side of the head, face, and upper part of the neck. NEUROLOGY. 309 Besides the two terminal branches, the facial nerve has four or five other branches,— three given off at its exit from the stylo-mastoid foramen (the stylo-hyoid, digastric, and posterior auricular branches), and one or two within the aqueductus Fallopii (the tympanic, and, according to several authors, the chorda tympani). The chorda tym- pani is, however, of doubtful origin. Some authors consider it a branch of the fifth pair (trifacial). It leaves the facial nerve at an acute angle, ascends in a distinct canal’ to the tympanum, passes forward through that cavity to its anterior inferior angle, and entering the canal of Huguier at the inner and upper side of the Eustachian canal, emerges from the bone at the inner side of the Glasserian fissure; descends between the two pterygoid muscles, meets the gustatory nerve (branch of the fifth pair) at an acute angle, accompanies it to the submaxillary gland, which it supplies, and then joins the submaxillary ganglion. Gray Fig. 220. COURSE AND CONNECTIONS OF THE FACIAL NERVE IN THE TEMPORAL BONE. tells us that this nerve terminates in the lingualis muscle, and some other authors say it is distributed to the mucous membrane of the anterior two thirds of the tongue, and governs the sense of taste; but considering the fact that the facial nerve is a nerve of motion, and also that the chorda tympani meets both the facial and gustatory nerves at an angle which militates against the theory of its cranial origin, we are led to believe that the chorda tympani is not a branch of the seventh (facial) pair, nor of the fifth, but is a sympathetic nerve, arising from the submaxillary ganglion, running for a short distance with the gustatory nerve, supplying the submaxillary gland, and then joining the facial nerve to be distributed upon the face. The trifacial and glosso-pharyngeal nerves preside over the sense of taste. The tympanic branch of the facial supplies the stapedius and laxator tympani muscles — both muscles of the tympanum. The temporo-facial branch is the larger of the two terminal branches of the facial. It passes upward and forward through the parotid gland ; crosses the neck of the condyle of the jaw, and divides into branches, which are distributed to the temple and upper part of the face. 310 NEUROLOGY. The ccrvico-facial (neck and face) branch passes downward and for- ward through the parotid gland, and opposite the angle of the lower jaw, divides into branches to the lower half of the face and upper part of the neck. The auditory nerve divides at the bottom of the internal ear-pas- sage into two branches, cochlear and vestibular, which are distributed, one to the cochlea, the other to the vestibule and semicircular canals of the internal ear (labyrinth). The glosso-pharyngeal nerve gives off six branches, or sets of branches: the tympanic (called, also, Jacobson’s), carotid branches, pharyngeal, muscular, tonsilar, and lingual. The tympanic branch supplies the membrane of the tympanum and Eustachian tube. The carotid branches descend along the internal carotid artery. The pharyngeal branches help to form the pharyngeal plexus, which supplies the mucous membrane of the throat. The muscular branches supply the stylo-pharyngeus muscle. The tonsilar branches form a plexus around the tonsil, and send branches to the soft palate and fauces (entrance to the throat). The lingual branches, two in number, are sent to the tongue. The glosso-pharyngeal nerve has two ganglionic enlargements within the jugular foramen, which are designated as superior and inferior, or the jugular and the petrous ganglion. Thq pneumogastric is one of the most important of all the cranial nerves. It gives off nine sets of branches, as follows: in the jugular fossa it gives off the auricular (Arnold’s nerve) to the integument of the auricle (pinna, pavilion, or external ear) ; in the neck it gives off the pharyngeal to the pharyngeal plexus; the superior laryngeal (to the larynx), which is a nerve of sensation ; the recurrent laryngeal (so called from its reflected course), which supplies the muscles of phona- tion (use of the voice); the cardiac branches (one in the neck and one in the thorax — cervical and thoracic), which help to form the cardiac (heart) plexus; in the thorax it gives off the pulmonary branches to the anterior and posterior pulmonary plexus; the oesoph- ageal to the oesophageal plexus; and in the abdomen the gastric branches, which send terminal branches to the stomach, spleen, and liver. The gastric branches may be traced to the coeliac, splenic, and hepatic plexuses. The pneumogastric has also two ganglionic enlarge- ments; one while within the jugular foramen (called the “jugular ganglion of the pneumogastric”), and the other after the exit of the nerve from the foramen (called the “ inferior ganglion,” or “ ganglion of the trunk ” of the nerve). These ganglia are connected with the sympathetic system. The two pneumogastric nerves descend the neck, one on either side, within the sheath of the carotid arteries (both NEUROLOGY. 311 internal and common), lying between the internal jugular vein and the carotid artery (the internal carotid in the tipper part of the neck, and the common carotid in the lower part). Below the root of the neck the course of the two nerves differs. The right pneumogastric passes down between the subclavian vessels (artery and vein), by the side of the trachea (windpipe), to the posterior pulmonary plexus, at the back part of the root of the lung; from this pulmonary plexus two cords descend upon the oesophagus, which help to form the oesophageal plexus, below which a single cord runs along the back part of the oesophagus to the coeliac and splenic plexuses in the abdomen. The left pneumogastric enters the chest between the carotid and subclavian arteries (on this side the subclavian artery extends to the arch of the aorta), crosses the arch of the aorta, and descends along the anterior surface of the cesophagtis to the stomach and left hepatic plexus. The spinal accessory nerve consists of two parts — the accessory and spinal portions. The accessory portion unites with the vagus (pneumogastric) by one or two filaments in the jugular foramen, but its main part unites with the vagus below the second ganglion. It gives branches to the pharyngeal, and superior laryngeal branches of the pneumogastric. The spinal portion of the spinal accessory arises from the spinal cord (by several filaments as low down as the sixth cervical nerve), ascends through the foramen magnum (great opening) of the occipital bone, and passes outward to the jugular foramen, through which it escapes from the cranium in the same sheath with the pneumogastric, but separated from it by a fold of the arachnoid membrane. It assists in the formation of the cervical plexus, and sends branches to the sterno-cleido-mastoid and trapezius muscles. The hypo-glossal (under the tongue) nerve gives off the descend- dens noni (descending of the ninth) and several muscular branches. The descendens noni is given off near the angle of the jaw, and is occasionally contained in the sheath of the carotid vessels. It is a long, slender branch, and supplies the sterno-hyoid, sterno-thyroid, and omo-hyoid muscles. The lingual branch of the hypo-glossal is the continuation of the principal trunk, and gives off numerous filaments to the muscles of the tongue and pharynx (throat). The cranial nerves may all be traced to some part of the surface of the base of the brain, where they have their superficial, or apparent origin; but their real, or deep origin is traced into the substance of the brain itself. The gray matter of the brain and upper spinal cord is ORIGIN OF THE CRANIAL NERVES. 312 NEUROLOGY. probably the real origin of all the cranial nerves. It is found in all the various ganglia of the brain, and interspersed between the white fibrous matter. The apparent origin of the olfactory nerves, is the olfactory bulbs that lie upon the cribriform plate of the ethmoid bone; but the real origin extends into the anterior and middle lobes of the cerebrum (upper brain). The apparent origin of the optic nerves is the optic tracts ; but these are traced to the corpora quadrigemina (four twin bodies), or optic lobes, which communicate with both the cerebrum and cerebellum (upper and back brains). The apparent, or superficial orgin of the motor oculi nerve is the crus cerebri (leg of the cerebrum), but its deep origin is traced across the pons Varolii (bridge of Varolius) to the corpora quadrigemina. The pathetic (trochlear) nerve arises from the valve of Vieussens (Veeur-sonsse), which is a thin plate of nervous matter above the fourth ventricle. The trifacial (fifth pair) has its superficial origin in the side of the pons Varolii, by two roots which are separated from each other by a few of the transverse fibers of the pons (bridge), but the deep origin is traced into the cerebellum and the medulla oblongata. The abducens (sixth pair) has its superficial origin by several fila- ments from the lower border of the pons, but its deep origin is traced to the posterior part of the medulla oblongata. The facial nerve arises from the medulla between the olivary and restiform bodies; and its fibers are traced to the same nucleus in the medulla as the sixth nerve (abducens). The auditory nerve has its superficial origin in the transverse lines of the harp (“lyra”), but its deep origin lies in the medulla and cerebellum. The glosso-pharyngeal nerve arises from the upper part of the medulla, and has its deep origin in a nucleus of gray matter in the floor of the fourth ventricle. The pneumogastric arises superficially from the side of the medulla (in the “lateral tract,” or column), and is traced to the same nucleus with the glosso-pharyngeal. The spinal accessory arises from the lateral tract of the medulla and spinal cord, having its deep origin in the gray matter, or ganglionic center of the cord. The hypo-glossal arises by ten or fifteen filaments from a groove between the olivary and pyramidal bodies of the medulla. The fila- ments are traced to a gray nucleus in the floor of the medulla. NEUROLOGY. 313 THE SPINAL NERVES. The spinal nerves have their superficial origin in the spinal cord, and are transmitted through the intervertebral foramina (formed by the intervertebral notches of the vertebrae) of the spinal column. There are usually thirty pairs of spinal nerves arranged in four groups corresponding to the region of the spinal column, in which they seem to originate. The four groups are the cervical, dorsal, lumbar, and sacral. The first pair is the suboccipital, which is included among the cervical. With this addition to the cervical, the number in each group corresponds to the number of vertebrae in each region, giv- ing eight cervical, twelve dorsal, five lumbar, and five sacral. Fig. 221. DIAGRAM OF A SPINAL NERVE, SHOWING THE ANTERIOR AND POSTERIOR ROOTS, ANTERIOR AND POSTERIOR BRANCHES, AND THE LATERAL AND ANTERIOR CUTANEOUS BRANCHES. Each spinal nerve is connected to the cord by two roots,— an ante- rior, or motor root, and a posterior, or sensory root. The anterior roots arise from the antero-lateral columns of the spinal cord, and the posterior roots from the posterior columns of the cord. If we reckon an anterior and a lateral column of the cord, then the anterior roots of the spinal nerves arise from a lineal series of foramina, which seem to divide the anterior and lateral columns of the cord. The two roots of each spinal nerve pierce the dura mater (the outer covering of the cord), and enter the intervertebral foramen of the spinal column. Within the foramen, upon each posterior root, with sometimes the exception of the first cervical nerve, is found a ganglion. Beyond the ganglion the two Fig. 222. DIAGRAM OF SPINAL NERVES. Fig. 223. DIAGRAM OF SPINAL NERVES. 316 NEUROLOGY. roots coalesce, and the common trunk passes out of the intervertebral, (between the vertebrae) foramen, and divides into an anterior branch for the anterior part of the body, and a posterior branch for the back part. Each branch contains fibers from both roots. In the cervical, lumbar, and sacral regions the anterior branches of the spinal nerves form intricate plexuses previous to their distribution; but in the dorsal region the anterior branches are separate from each other, and take the name of intercostal branches. The posterior branches supply muscles and integument behind the spinal column. The anterior branches of the first four cervical nerves form the cervical plexus, which lies in front of the four upper vertebrae, and is covered, on either side, by the sterno-cleido-mastoid muscle. The branches from the cer- vical plexus are divided into two groups,— superficial and deep ; and the superficial are again divided into the ascending and descending. The three ascending branches are the superficial of the neck (superficialis colli), the great of the auricle (auricularis magnus), and the small occipital (occipitalis minor). The only descending branch of the super- ficial group of the cervical plexus is the supraclavicular (above the clavicle), which divides into the sternal, clavicular, and acromial. These branches supply the integument of these regions. The deep branches of the cervical plexus are divided into internal and external branches. The internal are the communicating, muscular, communicans noni (com- municating of the ninth), and the phrenic. The communicating branches communicate with the pneumo- gastric, hypo-glossal, and sympathetic nerves. The muscular branches supply the anterior recti, and lateral rectus muscles of the neck. The communicans noni forms a loop with the descendens noni (descending of the ninth) of the hypo-glossal in front of the sheath of the carotid vessels. The phrenic nerve is the internal respiratory of Bell. It descends the neck, enters the chest between the subclavian vessels (artery and vein), crosses the internal mammary artery, and passes down through the diaphragm to supply its under surface. It also sends filaments to the pericardium and pleura. The right phrenic nerve is situated more deeply than the left. The external branches of the deep group from the cervical plexus are the communicating and the muscular. The communicating join the spinal accessory nerve. The muscular branches are distributed to the sterno-mastoid, levator anguli scapulae, middle scalene, and trapezius muscles. The anterior branches of the four lower cervical and first dorsal nerves form the brachial plexus. The brachial plexus extends from NEUROLOGY. 317 the lower part of the side of the neck into the axilla (armpit). The five anterior branches of spinal nerves, which form it at first, unite and form two trunks, which accompany the subclavian artery to the axilla (arm-pit), where they branch, and again unite to form three trunks, or cords (outer, inner, and posterior), which give off the terminal branches of the brachial plexus. Fig. 224. BRACHIAL PLEXUS AND ITS BRANCHES. The branches are divided into two groups by the position of the clavicle. Those above the clavicle are the communicating, muscular, posterior thoracic, and suprascapular. The communicating joins the phrenic which comes from the cervical plexus. The muscular branches supply the longus colli, the scalene, rhomboid, and subclavius muscles. The posterior thoracic (long thoracic, or external respiratory of Bell) supplies the serratus magnus muscle. The suprascapular supplies muscles on the back (dorsum) of the scapula (shoulder-blade). The branches of the brachial plexus, given off below the clavicle, are two anterior thoracic, to the pectoral muscles; the subscapular (three in number to the subscapularis, teres major, and latissimus dorsi Fig. 225. NERVES OF THE LEFT UPPER EXTREMITY. Fig. 226. SUPRASCAPULAR, CIRCUMFLEX, AND MUSCULO-SPIRAL NERVES. 320 NEUROLOGY. muscles) and circumflex to the shoulder; and six branches to the arm, forearm, and hand. The latter are three cutaneous (musculo-cutaneous, internal cutaneous, and lesser internal cutaneous),— the median, ulnar, and musculo-spiral. The circumflex nerve sends a filament to the shoulder joint, and supplies some of the muscles, and the integument (skin) of the shoulder. The musculo-cutaneous (called, also, external cutaneous) supplies some of the muscles of the arm — the coraco-brachialis, biceps, and brachialis anticus — and the integument of the forearm. The internal cutaneous is one of the smallest branches of the brachial plexus. It supplies the integument covering the biceps mus- cle and sends an anterior and posterior branch to the integument of the forearm. The lesser internal cutaneous nerve is the smallest of the branches of the brachial plexus. It is called, also, the nerve of Wrisberg. It passes through the axillary space along the inner side of the brachial artery to the skin upon the back part of the arm near the elbow. The median nerve (middle of the arm) arises from the outer and inner cords (or trunks) of the brachial plexus, which unite in front of the axillary artery, passes down the arm and forearm between the ulnar nerve on the inner side and the musculo-spiral and radial nerves on the outer, to the hand, where it gives off digital (finger) branches. In the forearm it gives off the palmar cutaneous, anterior interosseous, and mus- cular branches. The median gives off no branches above the elbow. The ulnar nerve runs along the ulnar (inner) side of the upper extremity, and is distributed to muscles and integument of the forearm and hand. At the elbow it rests upon the back of the inner condyle, between the inner condyle and olecranon (head of the elbow). The ulnar gives off articular (joint) branches to the elbow and wrist, two- muscular branches, a cutaneous and dorsal cutaneous, in the forearm; and, in the hand, a superficial palmar and deep palmar branch. The musculo-spiral nerve is the largest branch of the brachial plexus. It arises from the posterior cord of the brachial plexus in connection with the circumflex nerve, winds round the humerus in the spiral groove with the superior profunda artery and vein, passing from the inner to the outer side of the bone beneath the triceps muscle, and descends to the front of the external condyle, where it divides into the radial and posterior interosseous nerves. It gives off numerous muscular branches and three cutaneous branches. The radial nerve passes along the front of the radial side (the thumb side) of the forearm, a little to the outer side of the radial artery, but leaves the artery about seven centimeters (three inches) above the wrist, passes beneath the tendon of the supinator longus and divides into two branches. Fig. 227. Fig. 228. CUTANEOUS NERVES OF THE RIGHT UPPER EXTREMITY — ANTERIOR AND POSTERIOR VIEWS. 322 NEUROLOGY. The posterior interosseous nerve supplies muscles of the radial and posterior brachial regions. The dorsal nerves (second group of spinal nerves) are twelve in number on each side. As they emerge from the spinal column they divide into two branches (anterior and posterior). The posterior branches still retain the name of “dorsal,” but the anterior branches are called the intercostal nerves. The dorsal branches divide into external and internal branches. The external supply the longissi- mus dorsi, sacro-lumbalis, and levatores costarum (lifters of the ribs) ; and the six lower branches give off cutaneous filaments. The internal branches supply the multifidus spinas and semi-spinalis dorsi muscles, and the six upper branches give off cutaneous filaments. The intercostal branches (anterior branches of the spinal nerves in the dorsal region) supply the walls (parietes) of the chest (thorax) and abdomen without being joined in plexuses, like other anterior branches of the spinal nerves. Each intercostal nerve is connected with the adjoining ganglia of the sympathetic system. The branches of the intercostal nerves are the muscular and the cutaneous. The cutaneous are divided into lateral and anterior branches. The lumbar (loin) nerves are five in number on each side. They have the largest roots of all the spinal nerves, and the greatest number of filaments. Their roots come off from the lower end of the cord, and extend vertically downward in the spinal canal, to emerge through the intervertebral foramina (openings between the vertebrae) of the lumbar vertebrae, and divide into anterior and posterior branches. The anterior branches of the four upper lumbar nerves form the lum- bar plexus. The anterior branch of the fifth lumbar enters into the formation of the sacral plexus. The lumbar plexus is situated in the substance of the psoas muscle on each side, and in front of the transverse processes of the lumbar vertebrae. The lumbar plexus forms the seven following nerves: the ilio-hypogastric, ilio-inguinal, genito-crural, external cutaneous, ob- turator, accessory obturator, and the anterior crural. The first two, and part of the third of these seven, supply the lower part of the walls of the abdomen ; the rest are distributed to the forepart of the thigh and inner side of the leg. The ilio-hypogastric divides into the iliac and hypogastric nerves. The genito crural nerve divides near Poupart’s ligament into a genital and crural branch. The genital branch descends on the external iliac artery, and passes through the inguinal canal with the spermatic cord to the cremaster muscle in the male, and with the round ligament in the female. Fig. 229. Fig. 230. NERVES OF THE LOWER EXTREMITY ANTERIOR AND POSTERIOR VIEWS. 324 NEUROLOGY. The crural branch passes beneath Poupart’s ligament to the integu- ment of the upper part of the thigh. The obturator nerve supplies the obturator externus, the adductor muscles of the thigh, and the joints of both the hip and knee ; so that hip disease, which affects the obturator nerve, frequently causes pain at the knee. The anterior crural is the largest branch of the lumbar plexus. It passes beneath Poupart’s ligament, separated from the femoral artery by the psoas muscle, to supply muscles and integument on the front and inner side of the thigh, leg, and foot. Below Poupart’s ligament its branches form the long (or internal) saphenous, the middle, and internal cutaneous, articular, and muscular branches. The ante- rior crural nerve, as a whole, terminates in the thigh, by dividing into the anterior and posterior divisions. The muscular and articular branches form the posterior division of the anterior crural. The muscular supply the pectineus, and all the muscles on the front of the thigh except two (the sartorius and tensor vaginae femoris). The articular branches supply the knee-joint. The sacral, like all other spinal nerves, divide into anterior and posterior branches. The anterior branches of the upper three sacral nerves, with a part of the fourth, united with branches from the fourth and fifth lumbar nerves, form the sacral plexus. The fifth sacral nerve passes from the lower end of the sacral canal. The sacral plexus is triangular in form, with its apex at the lower part of the great sacro-sciatic foramen (large opening between the sacrum and ischium). The base of this triangle of nerves corresponds to the four anterior sacral foramina, of each side, that transmit sacral nerves. The sacral plexus, one on either side, is within the pelvis. The branches of the sacral plexus are the muscular, superior glu- teal, pudic, small sciatic, and great sciatic. All except a part of the first leave the pelvis through the great sacro-sciatic foramen. The muscular branches supply the pyriform, the internal obtu- rator, the two gemelli (inferior and superior), and the quadratus femoris. The superior gluteal supplies two of the three gluteal muscles— the middle and small gluteal. The pudic nerve leaves the pelvis through the great sacro-sciatic foramen, crosses the spine of the ischium, and re-enters the pelvis through the small sacro-sciatic foramen. It accompanies the pudic vessels,*and divides into the perineal nerve and “dorsal of the penis.” The small sciatic nerve supplies one muscle (the gluteus maxi- mus), and the integument of other parts (perineum and back part of the thigh and leg). Fig. 231. CUTANEOUS NERVES OF THE LOWER EXTREMITY — POSTERIOR VIEW. 326 NEUROLOGY. The great sciatic nerve supplies the greater part of the integu- ment of the leg, and the muscles of the back of the thigh, leg, and foot. It is the largest nervous cord in the body, and is the contin- uation of the lower part of the sacral plexus. It emerges from the pelvis through the great sacro-sciatic foramen, and divides in the thigh, usually below the middle, into the internal and external popliteal nerves. The internal popliteal nerve passes through the middle of the popliteal space, while the external popliteal passes along the outer side of the same space. The great sciatic descends between the great trochanter of the femur and the tuberosity of the ischium along the back part of the thigh. Besides the internal and external popliteal, it gives off articular branches to the hip joint and muscular branches to the flexors of the leg. Fig. 232. THE PLANTAR NERVES. The internal popliteal becomes the posterior tibial. The latter divides into the external and internal plantar, which supply the foot. The principal nerves that govern respiration are the pneumogas- tric, spinal accessory (superior respiratory), phrenic (internal respiratory of Bell), and the posterior, or long thoracic (external respiratory of Bell). 327 NEUROLOGY. SYMPATHETIC, OR ORGANIC SYSTEM OF NERVES. The sympathetic nerves were called by Bichat (pronounced Bee- shar) nerves of organic life, while the cerebro-spinal nerves were called nerves of animal life. The sympathetic nerves control the cir- culation of the blood, respiration, nutrition, and all the various vital processes. They are the involuntary nerves, not directly under the control of the human will. The sympathetic system consists of ganglia, plexuses, and nerves. The ganglia (knots) are nerve-centers. These are connected by branches of communication, and with the various organs, vessels, and viscera, by means of nerves which cross each other in an intricate Fig. 233. manner, and form a great number of plexuses (networks). The ganglia, which are generally recognized as parts of the sympathetic system, are situated within the great cavities of the head and trunk, on either side of the spinal column, and form a double axis extending from the cranium to the coccyx. They are all connected by branches of communica- tion, and by white nerve-fibers, with the brain and spinal cord. They are named, from their position, cephalic (in the head), cervical (neck), dorsal (back), lumbar (loins), sacral (in front of the sacrum), and coc- cygeal (situated in front of the coccyx). The cephalic ganglia may, perhaps, properly include all the num- erous nerve-centers of the encephalon, or brain; although anatomists usually reckon only four, or, at most, six cephalic ganglia con- NERVE CELLS, OR NERVE-CENTERS Fig. 234. SYMPATHETIC GANGLIA AND NERVES. NEUROLOGY. 329 nected with the sympathetic system. Gray mentions only four. These four are the ophthalmic (or ciliary), spheno-palatine (or Meckel’s ganglion), otic (or Arnold’s ganglion), and the submax- illary. Other authors add the ganglion of Ribes, situated upon the anterior communicating artery, and the Gasserian, or semilunar gang- lion, found upon the posterior root of the fifth cranial nerve. All of these are in pairs except the ganglion of Ribes, making altogether eleven ganglia. In addition to these, we find in the internal ear the “ganglion of Corti ” (a celebrated Italian anatomist), situated on the cochlear nerve (branch of the auditory) ; upon the glosso-pharyngeal nerve in the jugular foramen, the “jugular” and “petrous” ganglion; in the same foramen, another “jugular ganglion” upon the root of the pneumogas- tric nerve; and upon the trunk of the pneumogastric after it emerges from the jugular foramen, the “inferior ganglion,” which will increase the number of cephalic ganglia to twenty-one, besides the twelve great ganglionic bodies of the encephalon, usually enumerated in connection with the cerebro-spinal system. Below the base of the skull, the ganglia usually included in the sym- pathetic system form two gangliated cords, or a double axis, extending along on each side of the vertebral, or spinal column, parallel with one another as far as the sacrum, where they converge; and, in front of the coccyx, communicate through a small, single ganglion, called the “coccygeal,” or “ganglion impar” (odd ganglion). On account of the relation of these two series of ganglia to the ver- tebral column, the great sympathetic system has been called the “ver- tebral nerve.” Gall terms it the “nervous system of the automatic functions.” It was also called the “ trisplanchnic nerve,” because it gives origin to the three splanchnic (visceral, or intestinal) nerves. The two series of ganglia lying along the vertebral column from the base of the cranium to the coccyx, consist of twenty-four pairs,— three cervical, twelve dorsal, four lumbar, and five sacral,— all connected by communicating branches with each other and with the coccygeal ganglion (ganglion impar); and according to some authors with the ganglion of Ribes (a single and mesial ganglion) in the brain. Now, upon the posterior roots of the spinal nerves we find thirty pairs of ganglia, which are more or less intimately connected with the sympa- thetic system ; and if we include these and the ganglia found in con- nection with the cranial nerves, we shall have, altogether, one hundred and thirty of these ganglia, besides the twelve great ganglia generally enumerated as parts of the brain which is the center of the cerebro- spinal system. Small ganglia are also found in the substance of the 330 NEUROLOGY. heart, and two large gangliform masses (the semilunar ganglia) in connection with the solar plexus, making in all one hundred and forty- four sympathetic centers. The semilunar ganglia, two in number, are situated by the side of the coeliac axis, close to the supra-renal glands. The ophthalmic, or ciliary ganglion, is situated in the back part of the orbit, and is about the size of a pin’s head. Its branches are distributed to the ciliary muscle and iris. The spheno-palatine, or Meckel’s ganglion, is the largest of the four cephalic ganglia included in the sympathetic system. It is deeply placed in the spheno-maxillary fossa (space between the upper jaw and sphenoid bone), behind the palatine (relating to the roof of the mouth) branches of the superior maxillary nerve. It gives off numerous branches to the orbit, palate, nose, and throat. Among its branches are the palatine, naso-palatine, Vidian, and pharyngeal. The Vidian nerve passes backward through the Vidian canal in the sphenoid bone, and divides into the large petrosal and carotid branches. The large petrosal enters the hiatus Fallopii in the petrous portion of the temporal bone, and joins the facial nerve in the Fallopian aqueduct (aquaeductus Fallopii). The carotid branch of the Vidian enters the carotid canal to join the carotid plexus. The otic (“ear,” — it sends a branch to the middle ear, or tympa- num) ganglion, or ganglion of Arnold, is a small ganglion, although twice the size of the ophthalmic. It is situated near the Gasserian ganglion at the inner side of the inferior maxillary nerve. It sends a filament to the tensor tympani, and another to the tensor palati muscles. The submaxillary ganglion is situated above the deep portion of the submaxillary gland, within the angle of the lower jaw. It sends filaments to the submaxillary gland, and its duct (Wharton’s), and to the gustatory and facial nerves. The three cervical (neck) ganglia of the sympathetic system, or pairs of ganglia, are designated as superior, middle, and inferior. They are situated respectively nearly opposite the third, fifth, and seventh cervical vertebrae. The middle cervical is sometimes wanting. The cardiac (heart) nerves, three in number on each side (supe- rior, middle, and inferior cardiac), are derived from the cervical ganglia, and help to form the great cardiac plexus, which is situated in front of the bifurcation of the trachea, and behind the arch of the aorta. The dorsal, or thoracic ganglia of the sympathetic system rest against the heads of the ribs, and are covered by the parietal layer of the pleura (pleura costalis). The splanchnic (visceral) nerves, three in number on each side, are derived from the dorsal ganglia. The Fig. 235. DIAGRAM OF GANGLIA, PLEXUSES, AND NERVES OF THE SYMPATHETIC SYSTEM. 332 NEUROLOGY. great splanchnic nerve is formed chiefly by branches from the sixth, seventh, eighth, and ninth dorsal ganglia; the lesser splanchnic from the tenth and eleventh ; and the smallest (or renal) splanchnic from the twelfth dorsal ganglion on each side. The great splanchnic forms a large round cord of considerable size, which descends in the posterior mediastinum, perforates the crus (leg) of the diaphragm, and terminates in the semilunar ganglion. The lesser splanchnic passes through the diaphragm with the great splanchnic, and joins the coeliac plexus. The smallest splanchnic joins both the coeliac and renal plexus. The lumbar and sacral ganglia of the sympathetic system form numerous plexuses in the lumbar and sacral (or pelvic) regions. The more important plexuses of the sympathetic system are the carotid, situated on the outer side of the internal carotid artery; the great (or deep) cardiac, already described in connection with the car- diac nerves from the cervical ganglia; the superficial cardiac, be- neath the arch of the aorta; the solar plexus (called also the “ epi- gastric”), situated between the stomach and the crura of the dia- phragm ; and the hypogastric plexus, situated in front of the prom- ontory of the sacrum. The solar plexus supplies all the viscera of the abdominal cavity, and is intimately connected with the two semilunar ganglia (plural of ganglion). Numerous pairs of plexuses are derived from the solar plexus. The following may be named: the phrenic, coeliac (the coeliac subdivides into gastric, hepatic, and splenic), supra-renal, renal, spermatic, superior, and inferior mesenteric. Numerous ganglia, not previously mentioned, are developed upon the sympathetic nerves of the solar plexus in connection with the viscera. ORGANS OF SENSE. A sense is a faculty, possessed by animals, of perceiving impressions from natural objects. The senses are five in number: sight, hearing, smell, taste and touch. The organ of sense is the instrument by which the mind is brought into relation with the objects of sense. The skin is the principal seat of the sense of touch ; the tongue, of taste; the nose, of smell; the eye, of sight; and the ear, of hearing. The skin is the common integument (covering) of the body, the principal seat of the sense of touch, and an important excretory, or eliminating organ. It consists of two layers. The outer layer is called the cuticle (little skin), epidermis (upon the skin), or scarf-skin. The inner layer is called the “true skin” (cutis vera), or derma (Greek term for “skin”). The term “corium” is used by some authors as synonymous with derma, or cutis vera (true skin), and other authors use the same term to signify the deep layer, or base of the skin ; while the superficial layer is called the papillary layer, because it contains the papillae, which are the special organs of touch. The epidermis, cuticle, or scarf-skin, is epithelial (formed of flat- tened cells, or scales), and contains, at its base, the pigment (coloring) cells of the dark races. When the cuticle of the colored man is worn away, as it often is in the palm of the hand, the skin appears white. The under part of the cuticle, which contains the pigment cells, has been called the rete mucosum (mucous net) The outer part of the cuticle is, in some situations, hard and horny, depending much upon the amount of external pressure and friction. It is the outer flattened and hardened cells, retained in place by external pressure until numerous layers of hardened cells form beneath them, that constitute a “ corn ; ’’ and when these hardened cells, which, as a whole, take the form of an inverted cone that presses into the flesh, are removed, the corn is cured temporarily. The cuticle, or scarf-skin, is deciduous (falling off), like the outer bark of a tree, corresponding to the “ epithelium ” (membrane 334 ORGANS OF SENSE. of flattened cells) of mucous membranes. The cuticle is formed by the exudation (oozing of material through the pores) of cells, and contains neither blood-vessels nor nerves. The derma, or cutis vera (true skin), is tough, flexible, highly elastic, and when tanned, forms leather. Its frame-work is composed of interlacing bundles of white fibers, intermixed with a small propor- tion of yellow, elastic fibers. The interlacing of the bundles of fibers of the various tissues of the body forms intervening spaces, called areolae Fig. 236. INTEGUMENT, OR SKIN — MAGNIFIED. (diminutive of areas, and signifying little spaces) ; hence, tissue formed of interlacing fibers is termed fibro-areolar (composed of fibers and areolae) tissue. The true skin contains numerous blood-vessels, lym- phatics, and nerves. The fibro-areolar tissue of the skin is more abundant in the deeper layers; is more dense and firm, and has larger meshes (or areolae). Toward the surface, the fibers and meshes become finer; and the ORGANS OF SENSE. 335 superficial layer, which lies next to the rete mucosum (mucous net) of the cuticle, is covered with numerous small, conical, vascular (full of vessels, generally applied to blood-vessels) eminences, called papillae (nipple-like eminences, which contain the ultimate expansions of blood- vessels and nerves). The papillae of the mucous membranes of the body are generally called “ villi ’ ’ (“ tufts of hair,” because they are covered with fine down). The average length of one of the papillae of the skin is about .004 cen- timeters ( of an inch), and its diameter at the base, .0016 centimeters (sis of an inch). They are most numerous in parts endowed with great sensibility, as at the ends of the fingers and toes, where they are arranged in rows and curved lines, forming elevated ridges, which may be seen on, or through the cuticle, which covers them. The rows, or lines of papillae are sub-divided by transverse furrows, and thus regularly disposed into square-shaped masses, in the center of each of which is the microscopic opening of the duct of a sweat-gland, which forms one of the pores of the skin. The sweat-duct has a spiral form as it passes through the layers of the cuticle. The sweat-glands, together with hair follicles, sebaceous glands, and adipose (fatty) tissue, occupy the meshes, or areolae of the fibro-areolar tissue, which constitutes the framework of the skin. The nails, hairs, sebaceous and sweat glands are considered as ap- pendages of the skin. The nails and hairs are modifications of the cuticle, and when scalded, come off with it. The nails are placed upon the dorsal (back) surface of the ends of the fingers and toes. Each nail has a root, body, and free edge. The root is implanted into a groove of the skin; the exposed part covering the back of the digital (finger, or toe) extremity is the body ; and the anterior extremity, free on both surfaces, is the free edge. That part of the body of the nail near the root, which is of whiter color, owing to less vascularity of the papillae beneath, is called, from its appearance, “lunula” (little moon). The plural of this word is lunulae. The matrix (from mater, “ mother”) is that part of the cutis vera beneath the body and root of the nail on which the nail grows. It is by the growth of new cells at the root and under surface of the body that the nail ad- vances forward, and maintains its thickness. The chemical composition of the nails resembles that of the epidermis ; but the nails contain, pro- portionally, more carbon and sulphur. Hairs (Latin pili) are found on nearly every part of the surface of the body, excepting the palms of the hands and soles of the feet. They vary much in length, thickness, and color, in different persons and races. On some parts they are so short as not to project beyond the surface of 336 ORGANS OF SENSE. the part containing them ; while upon the scalp, in some instances (the Sutherland sisters), the hair has grown to the great length of more than two meters (seven feet). The hair in different parts of the body receives different names : that upon the head is termed a capillus (capitis pilus, — hair of the head) ; the eyelashes are the cilia (plural of cilium, “winker”) ; and that upon the face is termed, collectively, the beard. Each hair (pilus, or capillus) consists of a root, shaft, and point. The root is bulbous at its extremity, softer in texture than the shaft, and is lodged in a sheath of epidermis, formed by an inversion of the integument, and called the hair-follicle (little bag). When the hair is long, the follicle extends into the tissue beneath the skin. At the bottom of each hair-follicle is a conical (cone-like), vascular (full of blood-vessels) eminence, or papilla, upon which the root of the hair rests, and which supplies material for the growth of the hair. The papilla at the root of the hair is called “papilla pili” (papilla of the hair, or hair-papilla), although it is similar to those found upon the surface of the skin. The hair-follicles are usually implanted obliquely in the skin, so that the hairs lie down more or less flatly upon the sur- face of the scalp; but muscular fibers are so connected with these folli- cles that they can, by contraction, erect the hair, and cause it to “stand on end.” Opening into each follicle are one or more sebaceous (tallowy) glands. These glands are found in most parts of the skin, and often impart to individuals a peculiar odor, which can be perceived and dis- tinguished by sensitive persons. Their ducts (canals) most frequently open into the hair-follicles, but occasionally upon the general surface. The Meibomian glands, (named from Meibomius, although known long before his description of them) situated in special grooves in the tarsal cartilages of the eyelids, are sebaceous glands. The shaft, or stem of the hair, is usually described in three parts,— the medulla (middle part, or pith), the fibrous, and the cortex (rind), or cuticle of the hair. The medulla is sometimes wanting, and generally so toward the point of the hair. The medulla consists of rounded cells, more or less colored, and, usually, contains more or less air-cavities. When the air-cavities are very numerous in the medulla, caused by shrinking of the cells, the hair appears white (turns gray), on account of the light reflected from the walls of these numerous cavities, like those in the foam of water. The fibrous portion forms the chief part of the shaft. This portion is made up of fusiform (spindle-shaped) fibers, or greatly elongated cells, and contains pigment (coloring) granules, upon which depends chiefly the color of the hair. ORGANS OF SENSE. 337 The cuticle (or cortex) of the shaft is composed of flattened cells, or scales, which overlap each other like the scales of a fish, and have their free edges directed toward the point of the hair. In the hair-follicle, these scales interlock with the scales of the investing integument, and hold the hair quite firmly from falling. When a hair is lost, if the papilla at the root is not too severely in- jured, a new hair will be formed, but not otherwise. The growth of the hair depends upon the vigor of the circulation in the papillae. The same may be said of the nail in regard to the papillae of the matrix, The hair serves for ornament, for protection, and also as a conductor of electricity, which accumulates in the system. In the language of a friend of the author “It serves to connect the visible with the in- visible.” The sudoriferous (sweat-bearing) glands secrete the perspirable matter (sweat), and carry off from the blood a large proportion of its waste. They are found in almost all parts of the skin, and are so numerous that their number is estimated at two million. They are most numerous on the palm of the hand, where their number, accord- ing to Krause (pronounced Krou'za), is 2,800 on a square inch of integ- ument, or 500 on each square centimeter. On the back of the body, where they are least numerous, they number 70 on each cubic centi- meter, or 400 to the square inch. They usually lie in the sub-cutane- ous (under the skin) tissue ; and consist of one or more minute convo- luted tubes, with a spiral duct opening upon the surface. THE TONGUE. The tongue (lingua, glossa, or glotta) is a muscular and movable organ, situated in the mouth. Its name is synonymous with language, or speech, on account of its usefulness in articulation (the formation of joints, or syllables, in words). It is described by anatomists as the organ of taste, but has other important functions in eating, drinking, and speaking. Its upper surface, or dorsum (back) is free. Its lower surface is also free at the tip, or anterior third, while the body and base are attached to the lower jaw and hyoid bone. The base is also called the root of the tongue (radix linguae). The tongue is composed almost entirely of muscles, and is covered by mucous membrane, which has three varieties of papillae. It is these papillae that give to the tongue its characteristic roughness. They are distinguished by their size, and also by their shape. The great papillae are the “ circumvallate ” (en- vironed) ; the middle in size are called “ fungiform ” (mushroom- shape); and the small are “filiform” (thread-shape). 338 ORGANS OF SENSE. Fig. 237. UPPER SURFACE OF THE TONGUE. The circumvallate papillae are only eight or ten in number, are sit- uated far back upon the dorsum (“back,” or upper surface), and are arranged in the shape of a semi-circle, or letter “ V ”; the fungiform are scattered irregularly and sparsely over the dorsum of the tongue; Fig. 238. Fig. 239. THE THREE VARIETIES OF PAPILLAE ■—MAGNIFIED ORGANS OF SENSE. 339 and the filiform, or small papillae, cover the anterior two thirds of the dorsum. At the point where the two lines of circumvallate papillae meet, there is a fissure, or depression, called the foramen caecum (blind open- ing^— so-called because it terminates in a sac. A foramen of similar name is found in the frontal bone, and another in the medulla oblongata. The tongue is attached by folds of mucous membrane to the epi- glottis, and by the pillars of the fauces to the soft palate. A fold of mucous membrane beneath the tip of the tongue is called the fraenum linguae (bridle of the tongue). Fig. 240. MUSCLES, VESSELS, AND NERVES OF THE TONGUE. The substance of the tongue is made up of five pairs of muscles. These are the genio-hyo-glossus, hyo-glossus, lingualis, stylo-glossus, and palato-glossus, whose names indicate their attachments. The genio-hyo-glossus (chin, hyoid bone, and tongue) is a thin, flat, triangular muscle, placed vertically on either side of the median line, and beneath the body of the tongue. It is attached to the inner surface of the lower jaw at the symphysis (junction of the right and left sides ; the word symphysis signifies “growing together”), and from this point its fibers diverge like a triangular fan, to be inserted into the whole length of the under surface of the tongue. Some of the lower fibers are inserted into the body of the hyoid bone, and when contracted draw it 340 ORGANS OF SENSE. forward toward the chin, and a few are continued into the side of the pharynx (throat). At the back part of the tongue, the two muscles are separated by the fibrous septum, which extends through the middle of this organ. The lower and posterior fibers of these muscles protrude the tongue from the mouth, and their upper and anterior fibers retract it. Acting as a whole, they draw down the middle of the tongue, and render it concave from side to side. These muscles (the right and left) are supplied by the hypo-glossal (ninth cranial) nerves. Fig. 241. MUSCLES OF THE TONGUE LEFT SIDE. The hyo-glossus is also a thin, flat muscle, and extends from the side of the body and base of the tongue to the hyoid bone below. Its name indicates its attachments. It is described by some anatomists in three parts (basio-glossus, kerato-glossus, and chondro-glossus), owing to the different direction of its fibers, which are attached respectively to the body, greater horn (cornu), and lesser horn, of the hyoid bone. The hyo-glossus muscles draw down the sides of the tongue, and thus ORGANS OF SENSE. 341 render it convex from side to side. They are supplied by the hypo- glossal nerves. The greater part of the substance of the tongue is formed by the lingualis (tongue) muscle. Its fibers run in three directions : those upon the upper and lower surfaces are longitudinal, and extend from its base to the apex; between these are transverse fibers, which arise from the median septum (partition), and a large number of vertical fibers. The longitudinal fibers of the lower surface draw down the apex, and render the tongue convex from before backward ; the supe- rior longitudinal fibers draw up the apex, and render the tongue con- cave from before backward ; the transverse fibers narrow and elongate the tongue; and the vertical fibers flatten and broaden it,— supplied by the ninth cranial nerves (hypo-glossal). The palato-glossus (palate and tongue) is called, also, the con- strictor isthmi faucium (constrictor of the isthmus of the fauces). It forms the anterior pillar of the soft palate, and extends from the soft palate on each side of the uvula to the side and back of the tongue in front of the tonsil, and draws the base of the tongue upward, or the soft palate downward. The palato-glossus is supplied from Meckel’s ganglion. The stylo-glossus (styloid process and tongue) extends from the styloid process of the temporal bone downward and forward to the side of the tongue. It can draw the base of the tongue upward and back- ward, or, acting one side at a time, can turn the apex of the tongue to either side. The hypo-glossal nerves supply all the voluntary muscles of the tongue. THE NOSE. The nose is the organ of smell, or, more properly, the seat of the sense of smell. It consists of the external nose and internal nasal fossae. The nose, considered externally, occupies the middle part of the face, and forms a covering for the two anterior apertures (nostrils) of the nasal fossae. It is formed of bone above and cartilage below, and is covered by the common integument of the body, and lined with mucous membrane, which here takes the name of pituitary (mucus, or phlegm), or Schneiderian membrane. This membrane is continuous with that which lines the numerous cavities communicating with the nasal fossae, pharynx (throat), and tympanum (drum, or middle ear). The two nasal fossae are separated by a median wall, called the sep- tum. The septum, like the anterior walls of the nose, is partly bone and partly cartilage. The two nasal fossae communicate with the ex- Fig. 242. Fig. 243- BONES AND CARTILAGES OF THE NOSE. Fig. 244. PHARYNX, LARYNX, MOUTH, AND NASAL FOSSAE. ORGANS OF SENSE. 343 ternal air in front by means of two openings, called the anterior nares, or nostrils (nose-holes); and with the pharynx (throat) by means of the two posterior nares. If we speak of a single nostril, whether right or left, anterior or posterior, it is properly called naris (singular of nares). The external movable sides of the anterior nostrils are called the “alae” (wings) of the nose. A single wing is the “ala” (pro- nounced alar) of the nose. Each nasal fossa (cavity) is divided by the three turbinated bones into three meatuses (passages), called, respectively, the superior, middle, and inferior meatus (passage). The superior and middle turbinated bones are, in the adult, parts of the ethomid, but the inferior turbinated usually remain as separate bones. Each turbinated bone, on either side, is situated on the outer wall of the nasal fossa, above its corresponding meatus. The pituitary membrane is provided with a layer of mucous glands, which are most numerous at the middle and back part of the nasal fossae. The arteries of the nasal fossae are derived chiefly from the ophthal- mic and internal maxillary; but the external nose is largely supplied by the facial. The olfactory nerves have been traced over the upper third of the septum, and over the surface of the middle and superior turbinated (also called spongy) bones. THE EYES. The eye is the organ of sight, or vision. It is contained in a cavity of the cranium (skull) called the orbit. The eye (Latin, “ oculus”) has been called the window of the soul. In anatomy, the term “eyeball” is used in describing the organ of vision, as being more definite than the word eye. The orbits are two large pyramidal cavities formed by the aid of seven different bones, which afford protection to the eyeballs. It is the sight of these cavities, deprived of their peculiarly expressive organs, which gives to the skull its ghastly appearance, and yet in life they serve an excellent purpose. The eyeball is further protected by the eyelids, eyelashes, and eyebrows. The axes of the eyeballs are nearly parallel, while the axes of the orbits converge backward, so that their apices (plural of apex) are separated from each other only by the body of the sphenoid bone. The eyeball is almost a perfect sphere, and is called by some ancient and modern writers an “ orb,” but it has the segment of a smaller sphere engrafted upon its anterior part. 344 ORGANS OF SENSE. Fig. 245. THE EYEBALL, WITH THE OPTIC AND OTHER NERVES. The optic nerve enters the eyeball at its back part, and a little to the inner side. The eyeball is covered by three coats, and contains within it three refractive media. The coats in their order from without inward are the sclerotic (hard), the choroid (“skin-like,” having many vessels like the skin), and the retina (from “rete,” a net). The refractive media (two of them are called “humors” and one a “lens”) are the aqueous (watery) humor, the crystalline (“clear,” like ice) lens, and the vitre- ous (glassy) humor. The latter is also called the vitreous body. The sclerotic (hard) coat is the outer, firm, white covering of the Fig. 246. j. Anterior Chamber, filled with aqueous humor. 2. Posterior Chamber of the aqueous humcr. 3. Canal of Petit. VERTICAL SECTION OF THE GLOBE OF THE EYE. ORGANS OF SENSE. 345 eyeball. It gives shape and protection to the refractive media within, and also affords attachment for the six muscles that move the eyeball. The sclerotic coat, which is opaque, does not cover the segment of the smaller sphere in front, but its place is supplied by a transparent mem- brane called the “cornea” (horny substance). The cornea fits into the sclerotic coat like a crystal into the case of a watch. The sclerotic coat is that part which in common language is sometimes called the “white of the eye.” The choroid coat is the second covering of the eyeball. It lines the sclerotic internally, and its inner surface is covered like a camera obscura (dark chamber) with dark pigment, which absorbs the rays of light that fall upon the retina, and thus prevents reflection. Like the Fig. 247. COATS OF THE EYEBALL, YELLOW SPOT, AND CENTRAL ARTERY OF THE RETINA. sclerotic, the choroid coat does not completely cover the anterior por- tion of the eyeball, but leaves an opening, or window, for the admission of light. The opening is called the “ pupil” (little girl, or doll, from the image seen in the eye). The pupil is dilated (opened wider) and contracted (made smaller) by means of two sets of muscular fibers—a circular and a radiating set — contained in the iris (membrane around the pupil). The iris is continuous with the choroid coat, and is that part of the choroid which lies back of the cornea, and is differently colored in different persons. It is a perforated curtain, which graduates the amount of light admitted through its central opening. Its posterior surface is covered with a thick, black substance, and is called the uvea (from uva, "grape"), on account of the resemblance of its coloring-matter to the pulp of a black grape. Iris was the name of the rainbow. 346 ORGANS OF SENSE. Fig. 248. THE RETINA, AS SEEN FROM THE FRONT. The retina (from rete, “net”) is the third coat of the eyeball. It lies upon the inner surface of the choroid coat, and surrounds the vitreous body. The latter, the vitreous body, or humor, fills the Fig. 249. The lower part of the figure represents the innermost layers. LAYERS OF THE RETINA— MAGNIFIED. ORGANS OF SENSE. 347 greater portion of the eyeball, and is transparent, so as to admit the rays of light to the retina. The retina lines the posterior four fifths of the eyeball, extending in front to the base or outer margin of the iris. The hyaloid (glass-like) membrane separates the retina from the vitreous body. The retina is a semitransparent coat upon which the images are received. At its center, posteriorly, is the yellow spot (macula lutea), with a depression in its center called “fovea centralis” (central pit). A little to the nasal, or inner side of the yellow spot is the entrance of the optic nerve and central artery of the retina. The retina itself is divided into six or more layers. The external layer, unless we reckon a pigmentary layer which we have considered with the choroid, is the layer of rods and cones (usually called Jacob’s rods and cones) lying perpendicular to the surface ; then come successive layers, as given in Fig. 249; and last of all and next to the hyaloid is the internal limiting membrane (membrana limitans), which does not appear in the cut. The retina is the membrane to which is distributed the optic nerve. The vitreous (glassy) body, which comprises the greater portion of the eyeball, is a transparent mass of a gelatinous consistence that fills the eyeball behind the crystalline lens, extending from the retina behind to the crystalline lens in front. In early life the vitreous body is contained in large cells formed by the hyaloid coat which surrounds the vitreous body. The cavity filled by the vitreous body is called by some authors the posterior chamber of the eye, while other authors apply the same term to the space between the iris and the crystalline lens. To avoid confusion, we may designate the latter as the posterior chamber of the aqueous huvior. Fig. 250. THK CRYSTALLINE LENS, SHOWING ITS CONCENTRIC, OR ELLIPTICAL LAYERS. The crystalline lens is a transparent body, situated between the vitreous and aqueous (watery) humors of the eye, its anterior surface lying just behind the iris, but separated from it by a small quantity of the aqueous humor which passes freely through the pupil, and fills the 348 ORGANS OF SENSE. chambers on both sides (or surfaces) of the iris, which hangs like a curtain suspended in the watery (aqueous) humor. The crystalline lens is a double convex lens, with its anterior surface somewhat less convex than its posterior surface. The lens is composed of an albu- minoid substance inclosed in a capsule, called “ capsula lentis ” (capsule of the lens), and has a number of elliptical layers inclosed one within another, like a nest of boxes, or bowls. The aqueous humor fills the space, or spaces between the cornea in front and the crystalline lens which lies behind the iris. This space for the aqueous humor is divided in part by the iris into an anterior and posterior compartment, called chambers of the aqueous humor. These two chambers are separated in part only by the iris, and communicate through the central opening of the iris, called the pupil. Fig. 251. INSERTION OF THE RECTI MUSCLES. The ciliary muscle is a ring of involuntary, muscular tissue situated at the anterior part of the choroid coat, around the margin of the iris, and serving to adjust the eye to different distances by compressing the vitreous body and advancing the crystalline lens. In old age the lens usually becomes flattened on both surfaces. The suspensory ligament of the lens is a thin, transparent membrane that assists to retain the lens in position. The arteries of the globe of the eye are the ciliary and the arteria centralis retinae (central artery of the retina). The latter supplies the retina, and in the foetus, prior to the seventh month, sends a small branch forward through the vitreous body, to supply the crystalline lens. The nerves of the eyeball are the optic, the long ciliary (a branch of the nasal), and the short ciliary from the ciliary ganglion. When the optic nerve, or retina, is oppressed with too much light, the ciliary nerves, acting upon the circular fibers of the iris, contract the ORGANS OF SENSE. 349 pupil and exclude a part, and vice versa ; when there is too little light, the radiating fibers of the iris cause the pupil to dilate. The conjunctiva, eyelids, lachrymal apparatus, and eyebrows are generally described as appendages of the eye. The conjunctiva is a mucous membrane that lines the lids, and is reflected from the lids upon the globe of the eye, which it covers in front. Over the cornea it is little more than an epithelial layer. Fig. 252. THE LACHRYMAL APPARATUS, AND TARSAL CARTILAGE. The eyelids (palpebras) are movable folds, for the better protection of the eye, and also serve to keep the front of the eye, which is much exposed to the action of the atmosphere, in a properly moistened condition. The lids are two in number,— an upper and a lower lid. The upper lid (palpebra superior) is more movable, and is lifted by a special mus- cle, the levator palpebrae superioris (lifter of the upper lid). Fig. 253. THE LACHRYMAL GLAND, DUCTS, AND CANALS. 350 ORGANS OF SENSE. The angle where the upper and lower lids meet is called the can- thus (Greek word for angle, or corner). The two angles are distin- guished as the internal and external canthus. At the internal canthus, near the nose, the lids are separated by a small space called the lach- rymal lake (lacus lachrymalis). At the margin of the lake, on the edge of each lid, is a minute opening, called the punctum lachrymale (lach- rymal point), which is the beginning of the lachrymal (tear) canal. The latter conveys the tears through the nasal duct into the inferior meatus of the nose. The puncta lachrymalia (plural of punctum lach- rymale, “tear point”) terminate in the lachrymal sac, which is the upper dilated extremity of the nasal duct. Fig. 254. THE LACHRYMAL AND MEIBOMIAN GLANDS. The tears are secreted by the lachrymal gland, which lies above the globe of the eye near the outer angle of the orbit. They moisten the inner surface of the lids, and the latter moisten the cornea as they move over its surface in winking. The lid is composed of the tarsal cartilage, covered by the orbicular muscle and skin, and is lined with the conjunctiva. The Meibomian glands lie between the conjunctiva and tarsal car- tilage, and secrete a substance to prevent adhesion of the upper and lower lids. They are the largest sebaceous glands in the body. The eyelashes (cilia) are attached to the free edges of the lids, and serve for better protection of the eye. They are a picket-guard for the organ of vision. ORGANS OF SENSE. 351 THE EAR. The ear is the organ of hearing. It consists of three parts — the ex- ternal, middle, and internal ear. The external ear is also known by three other names; viz., auricle (little ear), pinna (wing), and pavilion of the ear. The middle ear is known as the tympanum (drum), and the internal as the labyrinth. The latter is the immediate seat of the sense of hearing. The tympanum serves only to convey the vibrations of the atmos- phere to the labyrinth ; and the external ear to direct the same into the external ear-passage (meatus auditorius externus). The external ear consists of cartilage covered with the common integument of the Fig- 255. THE EXTERNAL EAR. body, and attached to the bony margin of the external ear-passage. The deep depression of the auricle behind the meatus is the concha (a concave shell). Below the concha (pronounced kong-ka) is a soft pendulous portion, called the lobule (little lobe). The elevated rim, or outer circumference of the auricle, or pinna, is the helix (tendril of a vine). The smaller rim or ridge, between the helix and concha, is the anti-helix. In front of the meatus is a prominence called the tragus (a “goat,” on account of its beard in old persons); and opposite the tragus is a prominence in the smaller rim called the anti-tragus. The external meatus (meatus auditorius externus) extends from the concha to the membrane of the tympanum (membrana tympani), 352 ORGANS OF SENSE. which closes the passage completely, so that no insect or liquid can enter the ear farther than the outer surface of the membrane. The external passage is lined with the common integument (skin), which is here provided with glands that secrete the cerumen (wax). The wax lubricates the lining of the passage, and is probably offensive to insects. The tympanum (drum), or middle ear, is a cavity formed in the petrous portion of the temporal bone, and is separated from the external ear-passage only by a thin membrane called the “membrana tympani” (membrane of the drum). The tympanum communicates with the pharynx (throat), by means of the Eustachian tube, and contains a chain of three small bones, that serve to convey the vibrations of the membrana tympani to the labyrinth. These bones are the malleus (hammer), incus (anvil), and stapes (stirrup). The hammer is attached, by its handle (manubrium), to the membrana tympani, while its head strikes upon the anvil. The anvil connects the hammer with the stir- rup (stapes), and the foot of the stirrup closes the oval window (fenestra ovalis), which opens into the labyrinth. Fig. 256. OSSICLES (LITTLE BONES) OF THE EAR. A. The Malleus. B. The Incus. C. The Stapes. Each of these three bones of the tympanum has two processes: those of the malleus are the short and graceful; those of the incus are the short and long; and those of the stirrup are the two crura (legs), or branches. The latter form the sides of the stirrup. The long process (processus longus) of the incus terminates in a rounded pro- jection where it articulates with the head of the stapes. This rounded part of the incus (anvil), near the stapes, is a separate bone in the foetus ; or, in other words, is an epiphysis of the incus, and is called the “ os orbiculare” (rounded bone). It makes the fourth ear bone of the foetus. The graceful process (processus gracilis) of the malleus (ham- mer) gives attachment to the laxator tympani muscle, which, passing through the Glasserian fissure, is attached to the spinous process of the sphenoid. The short process (processus brevis) of the malleus gives attachment to the tensor tympani muscle. The foot of the stir- ORGANS OF SENSE. 353 rup is fastened to the circumference of the fenestra ovalis (oval window) by the annular ligament. The three muscles of the tympanum (drum), are the tensor tympani, laxator tympani, and stapedius. The tensor tympani (tightener of the drum) enters the tympanum by a small canal (canal of Huguier) just above the Eustachian tube. It draws the membrana tympani inward and heightens its tension. The laxator tympani (loosener of the drum) enters the tympanum by the Glasserian fissure. The stapedius arises from the sides of a conical cavity situated within an eminence of bone upon the internal wall of the drum, and called the pyramid. The stapedius depresses the back part of the base of the stapes (stirrup). Fig. 257. THE INTERNAL EAR, OR LABYRINTH, LAID OPEN ENLARGED. The internal wall of the drum is vertical (perpendicular to the horizon), is partly osseous (bony) and partly membranous, and sepa- rates the drum (middle ear) from the labyrinth (internal ear). The membranous part of the internal wall of the drum comprises the two membranes that close the windows (the oval and round, or fenestra ovalis, and fenestra rotunda). The oval window is situated above the round, and communicates with the vestibule of the labyrinth; the round communicates with the cochlea. On the posterior wall of the drum are the openings (one large and several small) from the mastoid cells. These cells are numerous, are situated in the mastoid process of the temporal bone, and are lined 354 ORGANS OF SENSE. with mucous membrane which is continuous with that of the tympanum (drum), or middle ear. The anterior wall of the tympanum has two openings — one small, for the canal of Huguier, and a larger one for the Eustachian canal. These canals run parallel with each other, and close together down- ward, forward, and inward toward the throat. The Eustachian tube lies in the Eustachian canal. It is four or five centimeters (about two inches) in length. The internal ear (the labyrinth) consists of the vestibule, three semicircular canals, and the cochlea (snail shell). The cochlea lies in front of the vestibule, with its base toward the internal ear-passage, Fig.258. COCHLEAR AND VESTIBULAR BRANCHES OF THE AUDITORY NERVE (PORTIO MOLLIS) IN CONNECTION WITH THE FACIAL NERVE (PORTIO DURA) ENLARGED. and its apex outward and forward. The vestibule (ante-room, or hall) is the common central cavity of communication between the parts of the labyrinth (winding maze). The osseous (bony) labyrinth consists of one central cavity (the vestibule) and four winding passages, which are chiseled out in the petrous portion of the temporal bone. This osseous labyrinth contains the membranous labyrinth, and within the latter are the branches ORGANS OF SENSE. 355 of the auditory nerve. The membranous labyrinth is filled with a fluid called the “ endolymph ” (clear fluid within), and is surrounded by a fluid called the perilymph (clear fluid around), which separates it from the osseous labyrinth. The three semicircular canals are distinguished as the superior, posterior, and external. They are all at right angles with each other; the superior and posterior canals being vertical, while the external is horizontal. They open into the vestibule. The membranous semicircu- lar canals are much smaller than the bony (osseous) canals in which they float. The bony canals themselves are chiseled out of dense bone, each in the form of a semicircle, and are large enough to admit the wire of an ordinary brass pin. The membranous semicircular canals are a part of the membranous labyrinth, which has the same general form as the osseous (bony) labyrinth in which it lies. The membranous labyrinth is a closed sac, held in position by numerous fibrous bands which stretch between the membranous and bony laby- rinths, and convey the blood-vessels and nerve filaments. Fig. 259. THE COCHLEA, LAID OPEN—ENLARGED. The cochlea (snail shell) is a spiral tube wound two and a half times round a hollow, conical axis (the “modiolus”). The modiolus is the central axis of the cochlea, and extends from its base to the apex. The modiolus transmits a small nerve and artery (arteria centralis modioli — central artery of the modiolus). The modiolus is further perforated by numerous branching canals, which transmit filaments of the cochlear branch of the auditory nerve. The spiral tube that winds two and a half times round the modiolus of the cochlea is called the “spiral canal.’’ It is about four centimeters (one and a half inches) in length, measured along its outer wall; and about one fourth of a centimeter (one tenth of an inch) in diameter at its commencement, but diminishes in size from the base to the summit. Small as it is, the spiral canal is 356 ORGANS OF SENSE. divided into three portions, forming three smaller canals, called scalse (ladders, or stairs). These three scalae, or canals of the cochlea, are named, respectively, scala tympani (ladder of the drum), scala vestibuli (ladder of the vestibule), and scala media (middle ladder). The scala tympani is the lower ladder, as it lies beneath the scala vestibuli. It commences at the round window (fenestra rotunda), where it is separated from the tympanum only by a thin membrane. The scala vestibuli communicates by an oval aperture with the vestibule, and at the apex of the cochlea with the scala tympani, by what is called the helico-trema (spiral foramen). This foramen exists in consequence of the deficiency of the septum (partition), which divides the two scalae (scala tympani and scala vestibuli) through two of the turns of the spiral canal, but is wanting in the last half turn. The scala media is a triangular section of the scala vestibuli, cut off from it by a membrane (membrane of Reissner) which extends from the edge of the bony lamina (plate) of the septum to the outer wall of the spiral canal. The septum, between the scala tympani and scala vestibuli, is called the lamina spiralis (spiral plate). It is partly osseous and partly membranous. The osseous part is called the osseous zone, and the other part the membranous zone, or basilar membrane. The osseous zone consists of two thin plates (lamellae) of bone, between which are numerous canals for the passage of nerve filaments. The scala media (middle ladder or staircase) is bounded by the outer curved wall of the spiral canal, by the membrane of Reiss- ner, and, lastly, by the basilar membrane. Within the scala media, and lying upon the basilar membrane which forms its floor, is the key- board of the ear — the “organ of Corti.” This organ consists of a series of arches and cells which form the termini (extremities) of the filaments of the cochlear branch of the auditory nerve. The cochlear nerves, or filaments (branches of the auditory) reach the organ of Corti by passing between the two plates of the osseous zone of the spiral lamina (plate). The auditory nerve divides at the bottom of the internal meatus into two branches — cochlear and vestibular. These branches sub- divide into numerous filaments before they enter the membranous labyrinth. At the ends of the osseous semicircular canals, where they enter the roof of the vestibule, the membranous canals which partially fill them are expanded, and from their shape, take the name of ampulae (bottles). The membranous semicircular canals communicate with the vestibule by five orifices ; the posterior and the superior semicircular canals uniting, at one end, before they enter the vestibule. ORGANS OF SENSE. 357 That portion of the membranous labyrinth which occupies the ves- tibule consists of two sacs,— the “utricle” (small bag) and the “saccule ” (small sac). Upon the wall of these little sacs is found, in each, a little round body composed of grains of carbonate of lime, held by a mesh of delicate fibrous tissue, and called the “otolith” (ear- stone). The otoliths are the weights that are supposed to determine the intensity of sounds. The semicircular canals probably enable us to determine the direc- tion in which the vibrations reach the ear. The entrance of air to the tympanum through the Eustachian ttibe affords an equal density of air upon either side of the membrani tym- pani, and thus prevents its injury. ORGANS OF DIGESTION. The organs of digestion (“ bear apart,” or distribute) consist of the alimentary (nourishing) canal and its accessory organs. The accessory organs are the tongue, teeth, salivary glands, tonsils, liver, spleen, pan- creas, lymphatics, and mesenteric glands. The tongue has been already described as an organ of sense. The alimentary canal is a tube of varying length and capacity, extending from the lips upon the face entirely through the chest and diaphragm (divider) into the abdomen (“ concealer,” because it conceals the viscera), where, after forming many convolutions, it terminates in the colon at the ileo-csecal valve. The colon (large intestine) was long regarded as a part of the alimentary canal; but the office which it performs as a drain, or sewer, for the system, as well as its shape and size, shows that it is something entirely different. The ingesta of the alimentary canal is supposed to be suitable for reception into the general circulation, but that of the colon is only suitable for rejection. The alimentary canal is for nourish- ment ; the colon is for waste, or refuse. The alimentary canal is lined throughout with mucous membrane, and furnished with a coat of muscular fibers governed by the sym- pathetic nerves. For convenience of reference and description, it is divided into parts, whose names, taken in order, are the mouth, isthmus faucium, pharynx (throat), oesophagus (food-carrier), stomach, duodenum, jejunum, and ileum. The mouth and stomach are dilata- tions of the alimentary canal. The duodenum, jejunum, and ileum, together, make up the small intestine. The small intestine extends from the stomach to the colon, and is one continuous tube, having no line of demarkation between the parts into which it is arbitrarily divided. The duodenum is the part next to the stomach, and is about twelve (duodena) fingers’ breadth in length. The jejunum (hungry, or empty) extends from the duo- denum to the ileum, and the ileum connects with the colon below. The ileum is generally considered longer than the jejunum, but the division is entirely arbitrary. The length and capacity of the alimen- tary canal depend upon the nature of the food. In the herbivora ORGANS OF DIGESTION. A. Stomach. B. Cardiac orifice. C. The duodenum. D. Commencement of the jejujium. E. The termination of the small in- testine at the ilio-ccecal valve. F. The ccecum. G. The vermiform appendix. H. Ascending colon. I. Transverse colon. J. Descending colon. K. Sigmoid flexure. L and M. The rectum. M. Pouch of the rectum containing the internal sphincter muscle. N. Anus and external sphincter muscle. O. Gall bladder. P. Gall duct. S. The point -where the common bile duct enters the duodenum. (Opp. Page 358.) ORGANS OF DIGESTION. 359 (animals that feed on vegetable food) it is much longer than in the carnivora (animals that feed on flesh). The mouth is the superior aperture, or entrance, to the aliment- ary canal, and is sometimes called the buccal cavity, from the Latin “bucca” (mouth, or cheek). In it we find provision for the mechan- ical division (mastication) of the food, and for its admixture with an alkaline fluid (the saliva) which is necessary for the process of digestion. The mucous membrane of the mouth is continuous upon the lips with the integument upon the face, and in healthy persons is tinged by the colors of the pink and the rose. It is lined with pavement epithelium. The mouth is bounded in front by the lips, at the sides by the cheeks, above by the palate (roof of the mouth), and behind by the isthmus faucium (isthmus of the fauces). The fauces (forks) are formed by the anterior and posterior pillars of the soft palate, and the isthmus of the fauces is the narrow passage of the alimentary canal which is guarded by these pillars. It is the constricted portion between the mouth and throat, and should not be confounded with the latter. The lips are two fleshy folds covered with integument, lined with mucous membrane, and containing the orbicularis oris (round of the mouth) muscle, blood-vessels (among these are the superior and infe- rior coronary arteries which are branches of the facial), nerves, areolar tissue, and numerous small labial glands. The inner surface of each lip is connected in the median line to the gum (gingiva, “ to beget,” because the teeth seem to be begotten in the gums) of the correspond- ing jaw by a fold of mucous membrane, called, respectively, the fraenum labii superioris (bridle of the upper lip), and fraenum labii inferioris (bridle of the lower lip). The labial glands are situated beneath the mucous membrane of the lips, around the orifice of the mouth, and open by small orifices upon the mucous membrane. They are about the size of a small pea, and resemble the other salivary glands. The cheeks, in a similar man- ner, contain “buccal” and “molar” glands. The cheeks cover the sides of the mouth as the lips do the front. They contain within them several muscles, but the principal are the buccinator, masseter, and zygomatic. The mucous membrane lining the cheeks is reflected above and below upon the gums (gingivae). Opposite the second upper molar tooth is the minute opening of the duct of the parotid gland. (This duct is called Steno’s duct, from Nicholas Steno). 360 ORGANS OF DIGESTION. The gums surround the necks of the teeth. They are composed of dense fibrous tissue closely connected to the periosteum of the alveolar processes. The gums are remarkable for their limited sensibility. THE TEETH. Two sets of teeth (dentes), and in rare instances three, are provided by nature. The first set, called temporary, deciduous (falling off), or milk teeth, appears in childhood ; the second set appears, usually, between the seventh and twenty-first years, and when properly used and well cared for, continue to extreme old age. The second set is called the permanent set, or permanent teeth. There are 20 temporary and 32 permanent teeth, one half in each jaw. Each half of each jaw contains of the temporary teeth, commencing at the median line in front, 2 incisors (cutting), 1 canine (dog tooth), or cuspid (pointed), and 2 molars (grinding). The permanent set contains, in addition, 2 bicuspids (two points) and 1 molar. Fig. 260. THE TEMPORARY TEETH. The temporary teeth are called deciduous (falling off), because they fall out. They are really pushed out, or removed, by the permanent teeth, which form in the jaw behind them. The temporary teeth begin to appear ordinarily about the seventh month, although in rare instances persons are born with teeth. The time of appearance is in general about as follows. Temporary set: incisors, seven to ten months; first molar, twelve to fourteen months; canine, or cuspid, fourteen to twenty ORGANS OF DIGESTION. 361 months; last molar, eighteen to thirty-six months. Permanent set: first molar, six and a half years ; incisors, seven and a half; first bicuspid, nine years; second bicuspid, ten years; cuspids, or canine, eleven years; second molar, twelve years; third molar (called also wisdom tooth), seventeen to twenty-one years. The lower teeth generally appear somewhat earlier than the corresponding upper teeth. Each tooth con, sists of three portions — the crown, or body, which projects above the gum ; the root, concealed in its socket (alveolus) beneath the gum ; and the neck, which is the constricted portion between the other two. The incisors, cuspids, bicuspids, and molars all differ somewhat in character. Fig. 261. Fig. 262. VERTICAL SECTION OF A BICUSPID AND A MOLAR TOOTH. The latter is the natural size, The incisors, eight in number, are the four front teeth in each jaw. They have a sharp, cutting edge, beveled* on the posterior surface like a chisel, and one long, conical fang, or root. The incisors of the upper jaw are larger than those of the lower ; and the two central are larger than those at the sides ; while the two central of the lower jaw are smaller than the two lateral incisors. The cuspids (having one point) are four in number, and are situa- ted one on each side of the four incisors in each jaw. The crown tapers to a blunt point, which extends beyond the level of the other teeth. The root is longer and thicker than that of the incisors, but conical in form, and sinks deeply in the jaw. 362 ORGANS OF DIGESTION. The bicuspids (two points) are eight in number, two behind each canine in each jaw. The crown is surmounted by two pyramidal emi- nences (cusps, or points), separated by a groove. The root is generally single, but presents a tendency to become double, as is seen by the groove on each side. The apex of the root is often bifid, especially that of the second upper bicuspid. The molars are twelve in number,—three placed behind each of the posterior bicuspids. The crowti of each molar is nearly cubical in form, flattened in front and behind, and surmounted by cusps. The Fig. 263. THE PERMANENT TEETH. first molar has usually five cusps ; the second has four in the upper and five in the lower jaw; and the third, or last molar, has usually three cusps. The roots of the molars have usually three fangs in the upper and two in the lower jaw. The roots of the wisdom teeth are shorter, and slightly curved. The temporary teeth resemble in form those of the corresponding permanent set. They lack the bicuspids and wisdom teeth. The fangs of the temporary teeth are generally more diverging from each other than those of the permanent teeth. The apex of each fang, or root of the teeth, has a small aperture, which transmits blood-vessels and nerves to the pulp cavity at the base of the crown. The pulp cavity is filled with the dental pulp (chiefly vessels and nerves). The solid portion of the tooth consists of three ORGANS OF DIGESTION. 363 substances,— dentine, which forms the larger portion of the tooth; enamel, which covers the crown ; and cementum, which forms a thin layer, resembling bone, on the surface of the fang. The dentine con- sists of a number of minute tubes (dental tubuli) imbedded in a dense homogeneous substance,— the intertubular tissue. The dental tubuli are placed parallel with one another, and open at their inner ends into the pulp cavity. The intertubular substance is translucent, finely granular, and contains the greater part of the earthy matter of the dentine. The earthy matter forms about 72 per cent of the dentine, consisting of phos- phate and carbonate of lime, fluoride of calcium, and other salts. The animal matter is principally gelatine. The enamel is the hardest part of the tooth. It consists of a con- geries of minute hexagonal (six-sided) prisms, or rods, parallel with one another, one end resting on the dentine, the other forming the surface of the crown. The enamel is above 96 per cent earthy matter, and less than 4 per cent animal. The cementum (crusta petrosa, or rocky crust) covers the roots of the teeth. It much resembles bone, and is called, also, cortical substance. It increases in thickness as age advances, and sometimes forms a bony tumor, called “exostosis” (from the bone). The sockets (alveoli) of the teeth are lined with perios- teum, which is reflected on the root of the tooth which it covers, and then unites with the fibrous structure of the gums. The palate is the roof of the mouth. It consists of two portions,—• the hard palate in front and the soft palate behind. The hard palate is formed of the palate processes of the superior maxillary and palate bones. The soft palate, or velum palati (veil of the palate), is a movable fold of mucous membrane suspended from the posterior border of the hard palate, and forming a septum (partition) between the back part of the mouth and the nasal fossae (cavities of the nose). It contains muscular fibers, nerves, vessels, and mucous glands. The muscles of the soft palate are five on each side: the levator palati, tensor palati, palato- glossus, palato-pharyngeus, and azygos uvulas. From the middle of the posterior border of the soft palate hangs the uvula (little grape), or uvule. This is a conical-shaped process of the soft palate, and contains the azygos uvulae muscle. The name “azygos” (unmated) is inappro- priate, as it is not a single rpuscle. Do not confound this pendulous body of the soft palate with the palate itself, which is the roof of the mouth. The pillars (or arches) of the soft palate are two folds of mucous membrane containing muscular fibers, and extending from the base of the uvule on each side, outward and downward, to the side of the base of the tongue. The two anterior pillars form one arch and the two posterior pillars the second arch. The anterior pillar on each 364 ORGANS OF DIGESTION. side contains the palato-glossus (palate and tongue) muscle, and the posterior pillar the palato-pharyngeus (palate and throat) muscle. The anterior and posterior pillars of the palate are separated below by a tri- angular interval on each side, in which the tonsil is lodged. The tonsils, or amygdalae (almonds), are two glandular bodies, situated one on each side of the isthmus faucium (“isthmus of the fauces,” or strait which connects the mouth and throat). Each tonsil has twelve or fifteen apertures upon the mucous surface, and lies in close relation to the internal carotid artery. Fig. 264. THE SALIVARY GLANDS. The principal salivary glands are the parotid (near the ear), the submaxillary (under the jaw), and the sublingual (under the tongue)— three pairs. The parotid is the largest, and weighs over half an ounce (sixteen grams). It lies immediately below and in front of the ex- ternal ear-passage, behind the margin of the ramus (branch) of the lower jaw, and extends deeply into the neck by two large processes, one behind and the other in front of the styloid process of the temporal bone. Important blood-vessels and nerves pass through its substance, and the largest artery and vein of the neck lie close to its deeper sur- ORGANS OF DIGESTION. 365 face. The facial nerve, which governs nearly all the muscles of expres- sion, as it emerges from the stylo-mastoid foramen, runs forward in the substance of this gland ; and the external carotid artery, with its termi- nal branches (temporal and internal maxillary), is imbedded within it. The duct of the parotid gland (Steno’s duct — named from Nicholas Steno) is about the size of a crow-quill. It is about six centimeters (two and one-half inches) in length, and extends from the anterior border of the gland across the masseter muscle through the buccinator to the inner surface of the cheek, where it opens into the mouth by a small orifice opposite the second molar tooth of the upper jaw. The submaxillary (under the jaw) gland is situated below the jaw in the anterior part of the submaxillary triangle of the neck. It is covered by the body of the lower jaw on each side, and is separated from the parotid gland by the stylo-maxillary ligament. Its secretion is carried into the mouth by Wharton’s (Thomas Wharton) duct, which is about five centimeters (two inches) in length, and opens by a narrow orifice at the side of the fraenum linguae (bridle of the tongue). The sublingual gland is the smallest of the three salivary glands. It is situated beneath the mucous membrane of the floor of the mouth, on both sides of the fraenum linguae, in contact with the inner surface of the lower jaw, and close to the symphysis menti (“ union of the chin ”—• median line in front, where the two sides of the lower jaw unite). Its ducts, eight to twenty in number, nearly all open separately into the mouth beneath the tongue, but one or more open into Wharton’s duct by one united tube (duct of Bartholine). The salivary are conglomerate (formed of small glands) glands, con- nected by areolar tissue, vessels, and ducts (canals, or tubes, through which fluids are conveyed). The pharynx (throat) is the common passage for aliment and air. It is that part of the alimentary canal situated behind the nasal fossae, isthmus faucium, and larynx. Its upper part has been called the sinus of Morgagni (pronounced Mor-gan-yee). The pharynx is a mem- branous sac, about eleven centimeters (four and one-half inches) in length, extending from the under surface of the skull to the cricoid (ring-like) cartilage of the larynx opposite the fifth cervical vertebra. It is limited above by the basilar process of the occipital bone ; below, it opens into the oesophagus (gullet); posteriorly, it lies against the bodies of the five upper vertebrae ; anteriorly, it is incomplete, and its walls are attached to the pterygoid (wing-like) processes of the sphe- noid bone, lower jaw, tongue, hyoid bone, and larynx; at the sides its walls are connected to the styloid processes of the temporal bone, and are in contact with the common and internal carotid arteries, the internal jugular veins, and with cranial and sympathetic nerves. 366 ORGANS OF DIGESTION. The pharynx has seven openings : the two posterior nares (nos- trils), the two Eustachian tubes, the isthmus faucium, the larynx, and the oesophagus. The posterior nares open into the nasal fossae (cavities of the nose) ; the Eustachian tubes into the tympana (drums, or middle ears); the isthmus faucium into the mouth ; the larynx into the lungs ; and the oesophagus into the stomach. The uvula, the base of the tongue, and the epiglottis, form part of the anterior wall of the pharynx. Fig. 265. FORMS OF GLANDS. D. and G. Tubular Glands. a. The Epithelial Layer. E. A simple Racemose Gland. e. One of the simple Racemose Glands. F. A compound Racemose Gland. One half of a highly developed racemose gland is seen upon the right. The pharynx has three coats — the mucous, fibrous, and muscular. The muscular coat comprises five muscles — the three (superior, middle, and inferior) constrictors of the pharynx, the stylo-pharyngeus, and the palato-pharyngeus. ORGANS OF DIGESTION. 367 The fibrous coat is situated between the mucous and muscular layers, and is called the “ pharyngeal aponeurosis.” This aponeurosis is firmly connected to the basilar process of the occipital bone, and to the petrous portion of the temporal. The mucous coat is the interior, or inner coat, and is covered by columnar ciliated epithelium, as low down as a level with the floor of the nasal cavities ; below that it is of the squamous (scaly), or pavement variety, which lines the mouth and isthmus. The mucous coat, or membrane, of the pharynx is supplied with glands (the pharyngeal) of two varieties—the simple follicular (a simple sac), and the racemose (in clusters, like grapes). The oesophagus (food-carrier, or gullet) is a membranous canal about twenty-two centimeters (nine inches) in length, extending from the pharynx (throat) to the stomach. It commences at the lower bor- der of the cricoid (ring-like) cartilage of the larynx, descends along the front of the spine through the posterior mediastinum (space be- tween the lungs), passes through the diaphragm with the pneumogas- tric nerves, a little in front of the aorta, and terminates in the abdomen at the cardiac orifice of the stomach, opposite the ninth dorsal vertebra. The coats of the oesophagus are similar to those of the pharynx. The outer muscular coat is composed of two planes of fibers — external longitudinal, and internal circular fibers. The muscular fibers of the upper part of the oesophagus are striped, like the voluntary muscles, but below they are involuntary fibers. The mucous membrane which lines the oesophagus is continuous with the mucous membrane of the pharynx. It is covered with a thick layer of squamous epithelium (a layer of overlapping scales, or flattened cells). Some glands (the oesophageal) are found beneath the mucous surface. The abdomen (concealer, because it conceals the viscera) is the largest of the three splanchnic cavities,— (cranial, chest, and abdomen). The abdomen is also called the “venter” (belly), or “alvus” ; hence “alvine” relates to the abdomen. The abdomen is bounded above by the diaphragm and below by the brim of the pelvis, although some authors include the pelvis in the abdomen. This great splanchnic (visceral) cavity (the abdomen) con- tains the stomach, the small and large intestine, liver, spleen, pancreas, kidneys, supra-renal capsules, the omenta, the mesenteric glands, arte- ries and veins, the abdominal aorta, the inferior vena cava, and numer- ous other glands, vessels, and nerves. In the abdominal walls are eight openings; and if we include the pelvis, we shall have ten openings in the male and eleven in the female. 368 ORGANS OF DIGESTION. Three of these openings are upward, through the diaphragm ; one (the aortic) transmits the aorta, vena azygos, and thoracic duct; a second (the oesophageal) transmits the oesophagus and the pneumogastric nerves; and the third (the caval) transmits the inferior vena cava. Five of the abdominal openings are in its anterior walls: one (the umbilicus) is in the median line of the body, and transmits in foetal life the two umbilical arteries and the umbilical vein, but becomes closed soon after birth by the obliteration of these vessels; and two are in each groin (the inguinal and femoral canal). The inguinal canal transmits the spermatic cord in the male, and the round ligament in the female; and the femoral canal transmits lym- phatic vessels to a lymphatic gland which generally occupies the femo- ral ring. The inguinal canal is above Poupart’s ligament, the femoral, below. Fig. 266. The femoral (or crural) canal is one or two centimeters (about half an inch) in length, and extends from the femoral ring above to the saphenous opening below. The femoral ring is closed by the septum crurale, and the saphenous opening by the cribriform fascia; hence a femoral hernia (protrusion of the bowel, or some part of the abdominal viscera) is covered by these two membranes in addition to others. In the floor of the pelvis are two abdominal openings in the male, and three in the female. These are the urethral, rectal, and in the female the vaginal, leading, respectively, into the bladder, rectum, and uterus. The abdomen is artificially divided into nine regions, by two verti- cal and two horizontal planes. The vertical planes extend upward, on THE NINE REGIONS OF THE ABDOMEN. ORGANS OF DIGESTION. 369 either side, from the middle point of Poupart’s ligament; and the hori- zontal are so drawn that the lower touches the crests of the ilia (plural of ilium), and the upper cuts the cartilages of the ninth pair of ribs. The regions thus limited are, on either side from above downward, the two hypochondriac, two lumbar, and two iliac (or inguinal) regions; and in the middle, the epigastric, umbilical, and hypogastric. Epigastric signifies “upon (or over) the stomach;” and hypogas- tric, “under the stomach.” The hypogastric region is also called the pubic region, because it is in the region of the pubic bone. Hypo- chondriac signifies “ under the cartilage,” having reference to the costal (rib) cartilages. Inguinal relates to the groin (depression between the belly and thigh) ; and lumbar to the loin (the posterior region of the abdomen between the chest and pelvis). According to this artificial, or conventional division of the abdomen, the stomach lies chiefly in the epigastric region, although the splenic (or cardiac [near the heart]) end of the stomach may reach, when the stomach is distended, the left hypochondriac region. The main part (right lobe) of the liver lies in the right hypochondriac region, but the left lobe of the liver extends into the epigastric region. The supra- renal capsules lie in the hypochondriac regions, but the kidneys lie partly in the hypochondriac and partly in the lumbar regions. The semilunar ganglia are in the epigastric region on either side of the cceliac axis. The ccecum is in the right iliac (or inguinal) region, and the sigmoid flexure of the colon in the left iliac (or inguinal) region. The two intestines (large and small) extend into all the abdominal regions. The peritoneum (stretched around) is a serous membrane which lines the abdominal cavity, and largely invests the viscera that fill it. It corresponds to the pleura of the chest, and forms numerous prolonga- tions, reflections, folds, and ligaments, that serve to connect the abdom- inal organs to each other, and also to the walls of the abdomen. Any fold, or prolongation, of the peritoneum which connects the stomach with an adjoining organ, takes the name of omentum, caul, or epiploon. The latter term signifies something that sails, or “floats upon,” and is particularly applicable to the great omentum which floats, upon (in front of) the folds of the small intestine. There are three omenta (or epiploa). These three connect the stomach (gaster) with the colon, spleen, and liver, and are named, respectively, the gastro- colic, gastro-splenic, and gastro-hepatic omentum. The gastro-colic (stomach and colon) is the great omentum,— the largest peritoneal fold. In the young subject it consists of four layers, two of which descend from the stomach (one from its anterior, the other from its 370 ORGANS OF DIGESTION. posterior surface) in front of the small intestine as low down as the pelvis ; then doubling upon themselves, ascend to the transverse colon, which they inclose. In the adult these four layers (two layers doubled upon themselves) are more or less intimately blended, and contain some adipose (fatty) tissue, which, in fat subjects, may accumulate in consid- erable quantity. The omentum protects the intestine from cold, and facilitates its movements. Fig. 267. L. Liver. C. Colon. B. Bladder. S. Stomach. I. Small Intestine. R. Rectum. DIAGRAM OF THE PERITONEUM. The arrows indicate surgical positions for puncturing the distended bladder. The gastro-splenic (stomach and spleen) omentum connects the spleen to the left extremity (the greater, or splenic end, called, also, the cul-de-sac, or fundus) of the stomach, and contains the splenic vessels (artery and vein). The gastro-hepatic (stomach and liver) omentum (the lesser omen- tum) connects the transverse fissure of the liver with the lesser curva- ORGANS OF DIGESTION. 371 ture (upper part) of the stomach, and forms Glisson’s capsule (a dense membrane surrounding the portal vein and its ramifications in the liver, and named from Francis Glisson). The mesentery and the mesocolon are also folds of the peritoneum. The mesocolon is divided into the mesocaecum, ascending, transverse, and descending mesocolon, sigmoid mesocolon, and mesorectum. The terms designate the parts connected. The mesentery (middle of the intestine) connects the middle line of the cylinder of the small intestine (jejunum and ileum) with the posterior wall of the abdomen, while the mesocolon connects the various parts of the colon, or large bowel, to the walls of the abdomen and pelvis. The root of the mesentery (the part attached to the vertebral column) is about fifteen centimeters (six inches) in length, and extends across the body of the second lumbar vertebra to the right sacro-iliac symphysis (union of the sacrum with the ilium) ; its other border which incloses the intestine, is much longer. Its breadth between its vertebral and intestinal border, is about ten centimeters (four inches). The mesentery serves to retain the small intestine in position (in situ), and contains between its layers the mesenteric vessels, nerves, glands, and lacteals (lymphatic vessels, that carry chyle). Other folds of the peritoneum form ligaments for the attachments of the liver, spleen, uterus, and bladder. Four of the five ligaments of the liver, one of the stomach (the gastro-phrenic, attaching the stomach to the diaphragm), five of the bladder (the five false ligaments), the six ligaments of the uterus (two in common with those of the bladder), and the suspensory ligament of the spleen (connecting it with the .dia- phragm), making eleven of the male and fifteen of the female, are all peritoneal folds. Many of the abdominal viscera are almost entirely covered with the visceral portion of the peritoneum, while others are only partially cov- ered. The lower part of the rectum and anterior portion of the bladder are not covered with peritoneum. The kidneys and pancreas, also, receive no special investment. The space between the visceral (investing the viscera) and parietal (lining the abdominal walls) portion of the peritoneum is called the peritoneal cavity. This general cavity is constricted at a part called the foramen of Winslow, which is said to connect the greater and lesser peritoneal cavity. The opening is large enough to admit the finger. (See Fig. 267.) . The free surface of the peritoneum, which forms the wall or lining of the peritoneal cavity, is smooth and moist, and is covered by a thin, squamous epithelium. 372 ORGANS OF DIGESTION. The stomach (Greek, “gaster”) is the most dilated part of the alimentary canal, and the principal organ of digestion. It is situated in the abdomen, just below the liver, and chiefly in the epigastric region. It has two ends, two curvatures, and two orifices. The ends are the greater and lesser ; the curvatures are also the greater and lesser, and two of its omenta are the greater and lesser; but the ori- fices are the cardiac and pyloric (gate-keeping). The greater end is on the left, toward the spleen, and is sometimes called the splenic end, or fundus (bottom) of the stomach. The pyloric orifice is at the lesser end, and opens into the duodenum, the aperture being guarded by a valve, or sphincter muscle. The cardiac orifice opens into the Fig. 268. THE MUSCULAR COAT OF THE STOMACH, SHOWING THE DIRECTION OF THE FIBERS. stomach from the oesophagus, and is shaped something like a tunnel placed bottom upward. It is situated near the middle of the upper border of the stomach, but somewhat nearer the greater end, so that the lower border of the stomach, extending from the pyloric orifice round the greater end of the stomach to the cardiac orifice, forms the greater curvature ; while the upper bprder, extending to the inner sides of the same orifices, forms the lesser curvature. The upper border (or lesser curvature) of the stomach is connected to the under surface of the liver by the lesser (gastro-hepatic) omentum; and the lower ORGANS OF DIGESTION. 373 border (the greater curvature) gives attachment to the great omentum (gastro-colic), which connects the stomach to the transverse colon. The principal coats of the stomach are the serous, muscular, and mucous. A fourth coat, called the submucous (under the mucous), or vascular coat, consists of areolar tissue, and connects the mucous and muscular coats. The submucous coat gives support to the blood- vessels distributed to the inner mucous coat, and also gives more firmness for the action of the muscular coat, which would otherwise act directly upon the inner mucous coat (or mucous membrane). The serous coat of the stomach forms its outer surface. It is derived from the peritoneum, and covers both the anterior and posterior surfaces of the stomach, but leaves a small triangular space uncovered, along the upper and lower borders (the lesser and greater curvatures), along which the nutrient vessels and nerves pass to this organ. The muscular coat is situated between the serous (outer) coat and the areolar tissue (the vascular, or submucous coat), which separates it from the mucous coat. The outer part of the muscular coat consists of longitudinal fibers, which are continuous with the longitudinal fibers of the oesophagus and small intestine; while the inner fibers of the mus- cular coat are circular, and are most abundant at the pyloric ori- fice, where they are aggregated into a ring, and form the pyloric valve. Besides these two sets of muscular fibers, there is, on the cardiac end of the stomach, a thick uniform layer of oblique fibers, some passing from left to right, others from right to left around the cardiac orifice. It is by the action of the muscular fibers that the food is moved and mixed with the gastric (stomach) juice. The mucous coat (more commonly called “ mucous membrane”) of the stomach is the inner coat. It is thick, smooth, soft, and velvety. During the contracted state of the organ it is thrown into numerous plaits, or wrinkles (rugae), which become obliterated when the organ is fully distended. Examined with a lens, the free surface of the mucous membrane appears like a honey-comb, on account of numerous polyg- onal (“many angles” and sides) depressions, or small cavities (alveoli), which vary in diameter from .025 centimeters ( of an inch) to .007 centimeters of an inch). In the bottom of each little cavity (alve- olus) are seen several minute openings (the orifices of the gastric fol- licles [small bags]). Some of the gastric follicles are simple tubes; others are convoluted, 'branching, and saccate. These follicles, or tubules, perpendicular to the free surface of the mucous membrane, form, or constitute, the mucous and peptic (digestive) glands. They are all lined with columnar (columns, or prismatic cells standing on end) ciliated (having fine hairs) epithelium. Epithelium (upon the 374 ORGANS OF DIGESTION. nipple) is a term applied to a thin layer of cuticle, which covers parts deprived of true skin, like the nipple and mucous membranes. The nerves of the stomach are the terminal branches of the right and left pneumogastric, and branches from the sympathetic system. The next portion of the alimentary canal, below the stomach, is the small intestine (bowel), divided into the duodenum, jejunum, and ileum. It is a convoluted tube, about six meters (twenty feet) in length, con- tained in the central and lower parts of the abdomen and pelvis, and surrounded above and at the sides of the abdomen by the large intestine (bowel), or colon. Fig. 269. MUCOUS MEMBRANE OF THE STOMACH AND DUODENUM, WITH THE BILE DUCTS. The duodenum (“twelve” fingers’ breadth in length) is the shortest and most fixed part of the small intestine. It is about twenty-five centimeters (ten inches) long, has no mesentery, and is only partially covered by the peritoneum. The duodenum, something like the arch of the aorta and colon, is divided into an ascending, descending, and transverse portion ; but, unlike them, the transverse portion is not the ORGANS OF DIGESTION. 375 second, but the third portion of the duodenum. Commencing at the pyloric orifice (or simply pylorus [gate-keeper]), the duodenum first ascends obliquely upward and backward to the under surface of the liver and neck of the gall bladder; then descends in front of the right kidney, embraces the head of the pancreas, receives the common bile and pancreatic ducts; and turning to the left, below the head of the pancreas, passes across the front of the spinal column, terminating in the jejunum, on the left side of the second lumbar vertebra. The second (or descending) portion is firmly fixed by the peritoneum and pancreas. The common bile duct and pancreatic duct enter this por- tion of the duodenum. The transverse portion rests upon (in front of) the aorta, the vena cava, and the crura of the diaphragm, and beneath (or behind) the superior mesenteric artery and vein. The nerves of the duodenum are traced to the solar plexus. Brunner’s glands are found in the duodenum and in the commencement of the jejunum. These glands, in structure, resemble the pancreas, and are most numerous and largest near the pylorus (gate-keeper). The jejunum (hungry) includes two fifths or more of the rest of the small intestine (or bowel). Its convolutions are confined, chiefly, to the umbilical and left iliac regions. There is no mark to distinguish its termination from the commencement of the ileum. The ileum (twisted, or coiled), so called from its numerous coils or convolutions, includes the lower portion of the small bowel. It occu- pies chiefly the umbilical, hypogastric, right iliac, and, occasionally, the pelvic regions, and terminates in the right iliac fossa by opening into the lower part of the ascending colon at the ileo-caecal valve. The coats of the small intestine correspond in number and name to those of the stomach. They are the serous, muscular, alveolar, and mucous. The serous coat is derived from the peritoneum (that part of it called the mesentery) ; the muscular has longitudinal and circular fibers, which produce the vermicular motion of the bowels; the alveolar (or submucous coat) gives firmness to the intestinal wall, and forms a nidus (nest) for the subdivision of nutrient vessels previous to their distribu- tion to the inner mucous membrane. The free surface of the mucous membrane is covered with columnar epithelium. The valvulse conniventes (little shutting valves) are folds, or reduplications, of the mucous membrane and submucous tissue, jut- ting into the cavity of the intestine. They serve to retard the pas- sage of food along the bowels, and afford a much more extensive sur- face for the lacteal vessels (lymphatics, or absorbents). They are large, and most numerous in the jejunum and lower part of the duode- num ; and the same may be said of the villi (papillae of the bowel), 376 ORGANS OF DIGESTION. although the villi (plural of villus) are found on the surface of the mucous coat throughout the small intestine; while the valvulae con- niventes are not found very near the pylorus nor at the lower part of the ileum. Krause estimates the number of villi at four million — about twice the number of pores in the skin. These estimates of the num- ber of pores and villi are only rough approximations to the truth. Each villus (papilla of the bowel) consists of a network of capil- lary and lymphatic (here called “lacteal”) vessels inclosed in a thin membrane, and covered by columnar epithelium. The mode of origin of the lacteal within the villus is unknown. Scattered among the villi are the minute orifices of the follicles of Lieberkuhn (pronounced Lee-ber-koon). Their use is unknown. The solitary glands are scattered throughout the mucous mem- brane of the small intestine, but are most numerous, as are also Peyer’s glands (Conrad Peyer), which are aggregations, or patches, of solitary glands, in the lower part of the ileum. These glands resemble in structure and function the spleen, thyroid, and supra-renal glands. They are small, round, whitish bodies about two tenths of a centimeter (one twelfth of an inch) in diameter, consisting of a closed cavity con- taining a white secretion, but having, so far as is known, no excretory duct. Peyer’s glands, or patches (twenty to thirty in number), are an aggregation of these glands in a single oval or circular patch. The use of these ductless glands is unknown. The colon (limb, or member), or large intestine, is the large bowel, and forms the lower part of the intestinal canal. The ali- mentary canal opens into it, as into a common sewer. The entrance is guarded by the ileo-caeca.1 valve. The intestinal (intus, “within”) canal may include both the large and small intestine, but the term alimentary (nourishing) canal is not applicable to the large intestine, whose function is excretory. The large intestine is called in general the colon, but is divided, more particularly, into the caecum, ascending colon, transverse colon, descending colon, sigmoid flexure, and rectum. These divisions depend chiefly upon the form and direction of the tube, or canal, which constitutes the colon. According to some authors, the colon is the part of the large intes- tine included between the caecum and rectum ; but the signification of colon (limb, or member) makes it applicable alike to the caecum and rectum. One author derives colon from a Greek word signifying “hollow,” and another from a word signifying to “retain,” thinking it refers to the retention of the ingesta of the large bowel for some time before it is discharged. Either of these two definitions — “hol- low,” or “retain” — applies with equal force to one part of the large ORGANS OF DIGESTION. 377 bowel as to any other part. The derivation which is first mentioned — “limb”—seems to mark the fact that the large intestine joins the small, as a limb joins the body, at an angle. And taking into considera- tion the general appearance of these parts, and their manifest similarity of form and function (office), we cannot find any good reason for limit- ing the colon to the middle part of the large bowel, but must extend it so as to include the caecum and rectum as beginning and end. The colon is so fixed in position as to describe an arch which very nearly surrounds the convolutions of the small intestine. It commences in the right iliac fossa (near the right groin) ; ascends in front of the Fig. 270. THE CHS CUM AND COLON, LAID OPEN TO SHOW THE VALVE. right kidney to the under surface of the liver, on the right of the gall bladder ; bends abruptly inward to the left, forming the hepatic (liver) flexure; passes transversely across the abdomen, describing an arch (transverse arch of the colon) in front of the vertebral column ; reaches the lower end of the spleen; curves downward, forming the splenic (spleen) flexure ; descends almost vertically in front of the left kidney to the upper part of the left iliac fossa; forms a curve like the letter S (the sigmoid flexure), enters the pelvis obliquely on the left of the median line, curves forward on the anterior concave surface of the sacrum and coccyx, and near the extremity of the coccyx inclines 378 ORGANS OF DIGESTION. somewhat backward to terminate at the anus. The term “anus” sig- nifies “ a circle,” and is applied to the circular opening at the lower extremity of the large intestine, which is called the “ rectum ” (straight). The rectum is not straight, however. It inclines (if we take the upward direction from the lower extremity), at first, slightly forward, till we reach the end of the coccyx ; then backward, along the con- cavity of the coccyx and sacrum, to the middle of the sacrum, where it turns obliquely to the left, to join the sigmoid flexure. Having traced the colon as a whole, we shall now describe its several parts more particularly. Its entire length is about one and a half meters (five feet). Fig. 271. 1. The Ileum. 2. The Caecum. 3. The Appendix Vermiformis. COMMENCEMENT OF THE COLON. The caecum (blind, because it is open only at one end) is that part of the large bowel, or colon, which lies below the ileo-caecal valve at the commencement of the ascending colon in the right iliac fossa, immediately behind the anterior abdominal wall, being retained in its place by the peritoneum (here called the mesocaecum). Attached to the lower and back part of the caecum, and opening into it, is a long, narrow, worm-shaped (vermiform) tube, or appendix, about the size and length of the tubular part of a goose-quill. It is the relic of the longer caecum, usually found in the lower mammalia (animals that suckle their young). The ileo-caecal valve is situated at the junction of the small intes- tine with the large, and is so constructed of folds of membrane as to allow any refuse or foreign matter of the small intestine to enter the ORGANS OF DIGESTION. 379 colon (large bowel) ; but prevent, ordinarily, the ingesta (substances “borne in”) of the large bowel from entering the ileum (small bowel). This valve is about six centimeters (two and a half inches) above the commencement of the large bowel, in the right iliac fossa ; or in other words, the small intestine enters the large about six centimeters (two and one-half inches) above its commencement. In cases of long and severe vomiting, the ileo-caecal valve yields to the reversed action. From the caecum the large bowel (here called the ascending colon) passes up to the under surface of the liver, where it forms the hepatic (liver) flexure, and becomes from this point the transverse colon. At the hepatic flexure the colon is connected by loose areolar tissue to the right quadratus lumborum (square of the loins) muscle and right kidney, which lie behind it. The transverse colon passes from right to left across the abdomen, between the epigastric and umbilical regions to the lower end of the spleen, where it curves downward (forming the splenic flexure) and becomes the descending colon. As it passes the spinal column from right to left, it curves in front of the bodies of the vertebrae, forming the transverse arch of the colon. This part of the colon (the trans- verse) is in relation, or connection, by its upper surface, with the liver, gall bladder, stomach, and lower end of the spleen, and by its under surface with the folds of the small intestine. The descending colon extends from the splenic flexure through the left lumbar region to the sigmoid flexure in the left iliac fossa. It is smaller, and more deeply placed, than the ascending colon. Its pos- terior surface is connected by areolar (or connective) tissue with the left kidney and left quadratus lumborum muscle. The sigmoid flexure extends from the margin of the crest of the ilium (part of the hip bone) to the left sacro-iliac symphysis (junction, or union of the sacrum and ilium), where it becomes the rectum. At first this flexure curves upward, then descends toward one side. It is retained in place by a loose fold of peritoneum. The rectum (“straight,” although it curves with the sacrum, and also passes obliquely downward and inward from the left side toward the median line) is the terminal part of the large intestine. It is fifteen or twenty centimeters (about seven inches) in length, and for more minute description, is divided into three portions, lower, middle, and upper. The upper portion comprises about half its length, and extends obliquely from the left sacro-iliac (sacrum and ilium) symphysis to the center of the sacrum, to which it is connected by the peritoneum (here called the meso-rectum). It lies behind the bladder, and in front of the pyriform muscle and sacral plexus of nerves. In the female the upper portion of the rectum lies closely behind the 380 ORGANS OF DIGESTION. uterus, which separates it from the bladder in front. The middle por- tion is six or seven centimeters (about two and a half inches) in length, and extends to the tip of the coccyx, closely connected to the concavity of the sacrum. It lies just behind the base of the bladder, the seminal vesicles (vesiculae seminales), and the vasa deferentia (“ outward bear- ing vessels,” meaning the spermatic ducts). In the female this portion of the rectum (the middle portion) adheres to the posterior wall of the vagina. The lower portion of the rectum is two or three centimeters (about an inch) in length. It extends from the tip of the coccyx to the anus, and curves backward as it descends. It is invested by the internal sphincter muscle, and surrounded at its termination by the external sphincter ani. A triangular space separates the lower portion of the rectum from the membranous portion and bulb of the urethra in the male, and from the vagina in the female. This space is filled by perineal muscles and fasciae. The rectum is not sacculated (divided into sacs, or compartments) like the rest of the large intestine. The large intestine, like the small, and the stomach, has, in general, four coats — serous, muscular, areolar (sub-mucous, or vascular), and mucous. The latter differs essentially from that of the small intestine. The serous coat is derived from the peritoneum, which is the serous membrane of the abdomen, and does not cover any portion of the ali- mentary canal above the diaphragm. In the abdomen it does not com- pletely cover all the different portions of the intestinal canal. The caecum, ascending and descending colon, and the middle portion of the rectum, are covered by this coat only in front; and the lower portion of the rectum is entirely devoid of any serous covering. Pouches of peri- toneum, filled with fat, along the colon and upper part of the rectum, are termed “appendices epiploicae ” (appendages of the epiploon). The muscular coat has longitudinal and circular fibers. It is the longi- tudinal fibers that give to the upper parts of the colon their peculiar sacculated character. When the tube is lengthened, or the longitudinal fibers are dissected off, the sacculated character of the tube becomes lost. The circular fibers are especially accumulated in the intervals between the sacculi (little sacs) ; and in the lower portion of the rec- tum they become numerous, and form a thick layer — the internal sphincter (the constrictor muscle) of the anus. The mucous membrane (or mucous coat) of the large intestine is destitute of villi (papillae),— another convincing proof that this part of the so-called alimentary canal is not properly alimentary, but excretory. The alimentary canal terminates properly at the ileo-caecal valve: the large bowel is different altogether. It is the main sewer of solids and semisolids. The simple follicles (little bags, or crypts) of Lieberkuhn ORGANS OF DIGESTION. 381 (pronounced Lee-ber-koon') are very numerous in the colon (large intestine), over its entire surface. They are secreting cavities, that open by small orifices into the large intestine. The colon is several times larger than the small intestine; is sacculated ; and its mucous surface is marked with orifices of numerous tubular glands, which may be traced to the margin of the ileo-caecal valve, but not above it. They are not found in the membrane of the small intestine, or alimentary canal. The relative length of the colon to the small intestine is as one to four; but, owing to its greater capacity, the extent of surface of the mucous membrane is about the same in both. THE LIVER. The liver is the largest gland in the body. It is situated in the right hypochondriac and epigastric regions, in direct contact with the under surface of the diaphragm, and weighs, ordinarily, about the same as the brain,— three or four pounds. It is an organ of fives, having five lobes, five ligaments, five fissures, and five sets of vessels. Fig. 272. THE UNDER SURFACE OF THE LIVER. The ligaments are the suspensory (longitudinal, or broad), the right and left lateral, the coronary, and the round (called also the liga- mentum teres). The five lobes are the right, left, square, caudate, and lobus Spigelii (lobe of Spigelius). The upper surface of the liver pre- sents but two lobes (the right and left) ; the other three are really parts of the right lobe, and can be seen only on the under surface. 382 ORGANS OF DIGESTION. The fissures are the longitudinal, transverse, cystic (for the gall bladder), caval (for the vena cava), and the venous duct fissure. The latter is really a part of the longitudinal fissure upon the under surface of the liver. The five sets of vessels are the hepatic duct, artery, and vein, the portal vein, and the lymphatics. The right lobe of the liver comprises at least five sixths of the entire organ. It is not only much thicker, being about seven centi- meters (or three inches) at the back part, but it is broader and longer than the left lobe; so that we may say that the main portion of the liver lies in the right hypochondriac region. The right lobe is divided Fig. 273. UPPER SURFACE OF THE LIVER. from the left, on the upper surface, by the longitudinal (broad, or sus- pensory) ligament, and on the lower surface by the round ligament and longitudinal fissure. At the anterior border of the liver these two lig- aments unite ; the round ligament, which runs along the longitudinal fissure on the under surface, being contained between the layers of the broad (longitudinal, or suspensory) ligament that runs along the upper surface. The broad ligament suspends the liver from the under sur- face of the diaphragm, and from the sheath of the right rectus muscle as low down as the umbilicus. The round ligament extends from the umbilicus (it is a fibrous cord, resulting from the obliteration of the umbilical vein), along the under surface of the liver, to the inferior vena cava. The broad ligament is formed by a fold of peritoneum. The ORGANS OF DIGESTION. 383 coronary and right and left lateral ligaments connect the posterior border of the liver with the diaphragm. The under surface of the right lobe of the liver presents three lobes and three fissures. The square lobe (lobus quadratus) and the lobe of Spigelius are separated from each other by the transverse fis- sure. The square lobe lies anteriorly between the longitudinal fissure and gall bladder; and the lobus Spigelii, posteriorly, between the lon- gitudinal fissure and inferior vena cava. The caudate (tailed) lobe (lobus caudatus) is only a small portion of the liver, which connects the lobus Spigelii with the main part of the right lobe, on the under surface. The under surface of the right lobe also presents two shallow depres- sions ; one in front, which covers the hepatic flexure of the colon, and one behind, which covers the right kidney and capsule. The left lobe of the liver rests upon the stomach (the front of the stomach), and extends into the left hypochondriac region, and some- times as far as the upper border of the spleen. The left lobe is thin and flat. The left and right lobes of the liver are sometimes joined together beneath the round ligament, as well as above, by a prolongation of hepatic substance (the pons hepatis, “liver bridge”) ; but this is only another way of saying that the round ligament (or umbilical vein of the foetus) sometimes r:ins through the liver, instead of beneath it. At the junction of the right and left lobes, on the under surface, is the commencement of the transverse fissure, which extends into the right lobe about five centimeters (two inches), and contains the primary branches of the portal vein, hepatic artery, hepatic duct, nerves and lymphatics. The older anatomists considered this fissure the gate- way (porta) of the liver, and called the large vein which enters at this point the portal vein (vena portae). The cystic (gall bladder) fissure is an oblong fossa on the anterior part of the under surface of the right lobe, parallel with the longitudinal fissure. It extends from the anterior border of the liver backward to the transverse fissure. The fundus of the gall-bladder usually projects slightly beyond the anterior free margin of the liver. The caval (for the vena cava) fissure is a short, deep fissure, occa- sionally a complete canal, on the posterior border of the liver, for the passage of the inferior vena cava. It is while lying in this fissure against the substance of the liver that the vena cava receives the hepatic veins. These veins usually terminate by two large and several smaller branches. The nerves of the liver are derived chiefly from the sympathetic and pneumogastric nerves. 384 ORGANS OF DIGESTION. The substance of the liver consists principally of liver (hepatic) cells which secrete the bile, arranged in minute groups (or lobules), and held together by blood-vessels, ducts, and lymphatics. The ducts from the lobules are the biliary (bile) ducts. These unite to form the hepatic (liver) duct. The hepatic and cystic (gall bladder) ducts unite and form the ductus communis choledochus (the common bile- duct). These ducts are all, in one sense, biliary, since they all convey bile, but bear distinctive names. The biliary ducts terminate in two trunks — one from the right and one from the left lobe of the liver. These unite (forming the hepatic duct) at the transverse fissure on the under side of the liver, pass downward about four centimeters (one and one-half inches), and join the cystic duct from the gall bladder, to form the common bile-duct. The latter is the common excretory duct of the Fig. 274. 1, 2. Longitudinal Fissure. 7. Left Lobe. 3. Transverse Fissure. 8. Lobus Spigelii. 4. Gall Bladder. 9. Lobus Caudatus. 5. Vena Cava. 10. Lobus Quadratus. 6. Right Lobe. THE UNDER SURFACE OF THE LIVER. liver and gall bladder. It is about eight centimeters (three inches) in length, and of the diameter of a small goose-quill. It usually empties, by a common orifice, with the pancreatic duct into the descending por- tion of the duodenum, passing obliquely between its mucous and mus- cular coats. The cystic duct is about an inch (two or three centime- ters) in length, and passes obliquely downward and to the left from the neck of the gall bladder to join the hepatic duct from the liver. It has an arrangement of its lining mucous membrane, presenting the appear- ance of a spiral valve, which is peculiar to the human subject. The gall bladder is a reservoir for the bile. It is ten centimeters (four inches) in length, and holds thirty or forty cubic centimeters (an ounce ORGANS OF DIGESTION. 385 or more). It lies under the liver immediately below the tenth costal (rib) cartilage. Whether the bile enters the gall bladder through the cystic duct, or through some more direct means, is uncertain. In some instances the cystic duct has become closed by a gall-stone, and the bladder has become, it was said, largely distended in consequence. See “ Holden’s Anatomy.” These cases, if correctly reported, are evi- dence of other means of ingress for the bile; or, possibly, the disten- tion arises from the mucous secreted by its inner coat, which is said to be abundant. The blood from which the bile is secreted is carried to the liver by the portal vein, while that destined for the nutrition of the organ is carried by the hepatic artery. THE PANCREAS. The pancreas (all flesh) is a glandular organ, that secretes the pancreatic juice, which is nearly identical with the saliva. It lies transversely across the epigastric region behind the stomach, extend- ing from the descending portion of the duodenum on the right to the Fig-275. THE PANCREAS, AND ITS RELATIONS. spleen on the left. The splenic, or left extremity, which is small and tapering, is called the tail, and the larger extremity, at the right, is called the head. 386 ORGANS OF DIGESTION. The pancreatic duct (canal of Wirsung) conveys the pancreatic juice, usually by one opening, but sometimes two, into the duodenum, which lies against the head of the pancreas. Usually, the pancreatic and common bile-ducts open into the small intestine by a common orifice, but sometimes separately. The average weight of the pancreas is about ninety-three grams (three ounces). THE SPLEEN. The spleen is a gland, but possesses no excretory duct. For this reason it is classified with the thyroid, thymus, and supra-renal as a ductless gland. It is situated in the left hypochondriac (under the car- tilage) region, at the left of the stomach, under the ninth and tenth ribs. It extends from the diaphragm above to the splenic flexure at the transverse colon below. The color of the spleen is a dark bluish-red, or reddish-blue, while the pancreas is a reddish-cream color. The lungs are pink, or pinkish- white in youth, but in old age often mottled with gray, or dark slate. The spleen is of oblong, flattened form, and weighs normally, on an average, two hundred and seventeen grams (seven ounces); although it is subject to great fluctuations in size, weighing, occasionally, nine kilograms (nine thousand grams, or twenty pounds). It is held in posi- tion by two folds of peritoneum: one, the gastro-splenic omentum, connects it with the stomach; and the other, the suspensory ligament of the spleen, connects it with the under surface of the diaphragm. It is also connected to the left kidney by loose areolar tissue. The splenic artery connects it with the coeliac axis and aorta, while the splenic vein, which helps to form the portal vein, connects it with the liver. The inner concave surface of the spleen has a vertical fissure, called the hilum (issue, or eye), which is pierced by several apertures for the entrance and exit of vessels and nerves. The spleen and kidneys contain Malpighian (pronounced Mal-pe- ge-an, with the “g” hard) bodies (corpora), or corpuscles (little bodies). The Malpighian bodies of the spleen are very large in well- fed animals, but in starved animals disappear altogether. They vary in size and number, and differ materially from those of the kidney. Each body consists of a membranous capsule, containing a soft, semi-fluid white substance, consisting of granular matter, or nuclei, and a few nucleated cells. The nerves of the spleen are derived from the semi- lunar ganglia of the sympathetic system and the pneumogastric nerves. The office of the spleen is still involved in obscurity. One author calls it a blood-lymph gland, or blood-vessel gland. By some it is consid- ORGANS OF DIGESTION. 387 ered the grave of the red corpuscles of the blood; but it is more likely the birthplace of,the ganglionic nerve-cells, as it is known to possess some mysterious influence over the nerves, and manifestations of mind. Mesenteric glands. These organs belong to the lymphatic sys- tem. They are situated between the layers of the mesentery, among the branches of the mesenteric arteries and veins. They vary in num- ber from one hundred to one hundred and fifty; and in size, from a pea to that of a small almond. They are most numerous near the extremities of the small intestine. The lower group become infiltrated and greatly enlarged in bad cases of typhoid fever. Consumption of these glands is called “tabes mesenterica” (mesenteric decay). It occurs most frequently in children whose nutrition is badly managed. Organs of Voice and Respiration. THE THORAX. The thorax (cuirass, or coat of mail), called, also, the chest, forms one of the great splanchnic (visceral) cavities, and is destined to lodge and protect the chief organs of respiration and circulation,— the lungs and heart. Fig. 276. A TRANSVERSE SECTION OF THE THORAX, SHOWING THE REFLECTIONS OF THE PLEURAE, THE MEDIASTINUM, ETC. The chest is a bony and cartilaginous framework, situated at the front and sides of the bodies of the dorsal vertebrae (the twelve bones of the back). Its walls are formed by the ribs, costal cartilages, ster- num, and dorsal vertebrae. It is bounded above on each side by the upper border of the first rib ; below by the diaphragm, which separates ORGANS OF VOICE AND RESPIRATION. 389 it from the abdomen. The apex of each lung projects through the upper opening of the chest a little above the first rib. The parts which pass through the upper opening are six muscles (the sterno- hyoid, sterno-thyroid, and longus colli, on either side), the trachea, thoracic duct, oesophagus, arteries, veins and nerves, and, in early life, the thymus body. THE LUNGS. The two lungs are the essential organs of respiration. They are sometimes called “lights,” because when not diseased they float in water. The right lung has three lobes; the left, two. The base of each lung rests upon the convex surface of the diaphragm. The space between the lungs is called the mediastinum. It is divided by the heart into anterior, middle, and posterior mediastina (plural of medias- tinum). The heart occupies the middle mediastinum. The anterior mediastinum is bounded by the sternum in front, by the pericardium (heart-case) behind, and by the pleura, which covers the lungs on each side. It contains the remains of the thymus gland, the internal mammary vessels, and the origins of three pairs of muscles which lie behind the sternum. The middle mediastinum contains the heart and pericardium, the ascending aorta, the superior vena cava, the bifurcation of the trachea (windpipe), the pulmonary vessels, and phrenic nerves. The posterior mediastinum has the heart and pericardium in front, the pleura at each side, and the vertebral column behind. It contains the descending aorta, the azygos veins, the pneumogastric and splanchnic nerves, the oesophagus, thoracic duct, and some lymphatic glands. The root of each lung is formed by the bronchus (large air-tube) and blood-vessels which enter the lung a little above the middle of the inner surface of each lung, and connect it to the heart and trachea (windpipe). With the exception of the root the surface of each lung is free, and moves in the cavity of the thorax (chest). The color of the lungs is usually a light pink, but is altered by the condition of the blood. The bronchus is one of the two tubes which arise from the bifurcation of the trachea (windpipe), and conducts the air from the trachea to either lung. Both tubes together are called the bronchi (plural of bronchus). The bronchial tubes are subdivisions, or ramifi- cations of the bronchus, and terminate in the alveoli, which contain the air-cells of the lungs. The bronchial tubes are lined with mucous membrane, and are supplied with a muscular coat, which forms a layer 390 ORGANS OF VOICE AND RESPIRATION. of annular fibers. Each air-cell has a diameter of about one one-hun- dredth of an inch (one fortieth of a centimeter). The air-cells them- selves are lined by pavement epithelium ; but the mucous membrane of the tubes (bronchial tubes) that conduct the air to the lungs, is lined with columnar ciliated epithelium ; i. e., a layer of cells in the form of columns, or rods, standing on end, and covered at the free surface with Fig. 277. FRONT VIEW OF THE HEART AND LUNGS, AND LARGE BLOOD-VESSELS. fine, hair-like projections, called cilia. Pavement epithelium is a layer of flattened cells. Besides the air-cells and air-passages, the lungs con- tain the pulmonary and bronchial vessels, nerves, lymphatics, and elastic tissue. The pulmonary vessels carry the blood of the entire system from the right ventricle to the left auricle of the heart, through the substance of the lungs. The bronchial vessels comprise the bronchial arteries and veins. The bronchial arteries, usually three in number, derived from the thoracic aorta, supply the parenchyma (sub- stance) of the lungs for nutrition. The bronchial veins return the PULMONIC CIRCULATION. (Opp. Page 390). ORGANS OF VOICE AND RESPIRATION. 391 blood from the substance of the lungs through the vena azygos and superior intercostal vein to the upper vena cava and right side of the heart. The nerves of the lungs are derived from the pneumogastric, cer- vical, and sympathetic. Each lung is covered by a serous membrane, called the pleura (a Greek word signifying “the side”). Each pleura is a shut sac, con- taining the plural cavity, which, in health, is scarcely a cavity at all, since that portion (visceral portion) which invests the lung lies in close contact with the parietal (wall) portion that lines the chest. A fold of pleura binds the root of the lung to the upper surface of the diaphragm. The pleura secretes a thin fluid, which facilitates the motion of the lung in the chest. THYROID GLAND. This organ is one of the so-called ductless glands. It is considered by some a blood-vessel gland. It is situated in the neck in front of the trachea (windpipe), lying across the upper part of the trachea and lower part of the larynx. It is just below Adam’s apple (pomum Adami). It consists of two lobes joined by an isthmus. Its normal weight is about fifty grams (one or two ounces). The isthmus is one or two centimeters (half an inch) in breadth, and lies transversely across the third or fourth ring (or cartilage) of the trachea. Each lat- eral lobe is about two inches (five centimeters) in length, and extends from the lower horns (cornua) of the thyroid cartilage to the level of the fifth ring of the trachea. The thyroid gland is subject to great enlargement in certain locali- ties (usually at the bases of lofty mountains); forming a “goitre” (from “guttur,” throat), which is often called bronchocele (tumor of the windpipe). There seems to be a communication between the thyroid gland and larynx. Lalouette, a French writer, says that the thyroid gland is frequently affected with aerial tumors (air swellings) ; and Haller informs us that Borden inflated the thyroid gland from little orifices in the first ring of the bronchus. Mr. Fodere inflated the gland from the larynx, secured below by a ligature. In structure the thyroid gland somewhat resembles the lungs. The arteries of the thyroid gland are remarkable for their large size and frequent anastomoses (intercommunication). The arteries are the superior and inferior thyroid, and sometimes an additional branch from the innominate. 392 ORGANS OF VOICE AND RESPIRATION. THYMUS GLAND. The thymus gland is a temporary organ, attaining its full size at the end of the second year, and nearly disappearing at puberty. It lies below the thyroid, and partly in the chest (the anterior mediasti- num). It is five centimeters (two inches) in length, and one centime- ter (about one third of an inch) in thickness. At birth it weighs about fifteen grams (one half ounce). It has a central cavity, which is pro- longed into subordinate cavities. The cavities contain a fluid resem- bling chyle (“juice,” — the nutritive fluid taken up by the lacteals). No duct has been described, and it is usually classed with the supra- renal capsules, spleen, and thyroid gland, as “ ductless.” THE TRACHEA. The trachea (air-tube), or windpipe, is a cylindrical tube extending from the lower part of the larynx opposite the fifth cervical vertebra to the level of the third dorsal (back) vertebra, where it divides into two branches (the right and left bronchus), that carry air to the lungs. It lies partly in the neck and partly in the chest, being in front of two or three lower cervical, and as many upper dorsal vertebrae. The oesoph- agus (food-carrier) passes down behind it. The trachea is a fibrous tube, with rings of elastic cartilage so imbeded as to prevent the tube from collapsing. The rings, however, are incomplete, being open behind like a horseshoe, the incomplete portion being supplied with a more yielding membrane in front of the oesophagus. The rings number sixteen to twenty in the trachea, six or eight in the right bronchus, and from nine to twelve in the left — the left bronchus extending a little lower down before it enters the left lung. The trachea is eleven or twelve centimeters (four and one-half inches) long, and about two centi- meters (four fifths of an inch) in diameter. It is larger in the male, and can be readily felt in the neck below the thyroid cartilage (Adam’s apple). The right bronchus is two or three centimeters (one inch) long, the left nearly twice as long. The bronchi subdivide into small and smaller tubes, which finally open into the alveoli (little cavities) of the lungs, that contain the air-cells; that is to say, the air-cells are grouped together in sacculated cavities, called alveoli. The trachea is lined with mucous membrane, which is continuous with the lining of the larynx above, and is covered on its free surface with columnar ciliated epithelium (layers of cells resembling rods set on end and covered with fine hairs [cilia]). ORGANS OF VOICE AND RESPIRATION. 393 Fig. 278. LARYNX, TRACHEA, AND BRONCHI. THE LARYNX. The larynx is the principal organ of voice. It is situated at the front part of the neck, and forms a prominence known as Adam’s apple (pomum Adami), and also a part of the anterior boundary of the pharynx (throat). At the upper part it has the form of a triangular box, with one angle directly in front. It is composed of nine carti- lages, moved by muscles, and lined by mucous membrane. Six of its 394 ORGANS OF VOICE AND RESPIRATION. cartilages are in pairs; three are single. The three single cartilages are the thyroid, cricoid, and epiglottis; the three pairs are the arytenoid, cuneiform, and the cornicula laryngis. The latter are some- times parts of the arytenoid. The thyroid (Bvpeoia shield) cartilage is the largest, and con- sists of two halves, that meet in front and form an angle; but separate behind so as to inclose a space where several of the remaining carti- lages are found. The two halves of the thyroid are called plates (lamel- lae), or wings (alae). The inner surface of each wing (ala) is smooth, Fig. 279. SIDE VIEW OF THE LARYNX, AND TWO RINGS OF THE TRACHEA. concave, and covered by mucous membrane. At their junction in front,, near the upper border, and on the inner surface, is attached the epi- glottis, which serves to close the glottis during the act of swallowing (deglutition). Just below the attachment of the epiglottis, and near the anterior median line, the anterior ends of the vocal cords are attached. The upper border of the thyroid cartilage is deeply notched in front, and terminates posteriorly, on either side, in a horn (cornu), which pro- jects upward. To the upper border is attached the membrane (thyro- hyoid), which connects the thyroid cartilage with the hyoid bone- Each upper horn gives attachment to a ligament (the thyro-hyoid), which connects the thyroid cartilage with the hyoid bone. ORGANS OF VOICE AND RESPIRATION. 395 The lower border of the thyroid cartilage is connected in front to the cricoid (ring-like) cartilage below by a membrane (the crico- thyroid), and at the side by a muscle (the crico-thyroid muscle), which increases the tension of the vocal cords by drawing down the thyroid cartilage over the cricoid. The lower border of the thyroid cartilage also terminates posteriorly on each side, in a horn (cornu), which pro- jects downward; or, we may say in other words, the two posterior borders of the thyroid cartilage terminate above in two superior horns Fig. 280. SIDE VIEW OF THE MUSCLES OF THE LARYNX. RIGHT WING OF THE THYROID CARTILAGE REMOVED. (cornua), and below in two inferior horns. The inner surfaces of the inferior horns articulate with the outer surface of the cricoid cartilage,— or, in other words, embrace the cricoid. The outer surface of the thy- roid cartilage gives attachment to a muscle (the sterno-thyroid) con- necting it with the sternum, to another (the thyro-hyoid) connecting it to the hyoid bone, and to a third (the inferior constrictor of the phar- ynx) which assists deglutition (swallowing). The cricoid (ring-like) cartilage forms the lower and back part of 396 ORGANS OF VOICE AND RESPIRATION. the larynx. Its anterior part is narrow, but its posterior is much deeper and broad, so as to present the appearance of a signet ring, with the signet, or seal, placed behind. The lower border of the cricoid is con- Fig. 281. POSTERIOR VIEW OF THE CARTILAGES OF THE LARYNX. nected with the first ring of the trachea, by fibrous membrane. The upper border is connected, in front, with the thyroid cartilage above; at the side, to the lateral cryco-arytenoid (connecting the cricoid and arytenoid cartilages) muscle; and on each side of the median line ORGANS OF VOICE AND RESPIRATION. 397 behind, by two articular surfaces, with the arytenoid cartilages, to which are attached the posterior extremities of the vocal cords. The two arytenoid (ladle-like) cartilages are situated posteriorly above the cricoid, and serve, by approximation, to diminish the aperture of the glottis. The two cornicula laryngis (little horns of the larynx) are mere nodules of cartilage, situated at the apex of each arytenoid cartilage, and sometimes united to the latter; in which case the num- ber of cartilages in the larynx is diminished to seven. The cuneiform (wedge-form) cartilages are two small elongated bodies, placed one on each side in the fold of mucous membrane that extends from the apex of the arytenoid cartilage to the side of the epiglottis. Fig. 282. INTERIOR OF THE LARYNX—'SEEN FROM ABOVE (ENLARGED). The epiglottis (signifying “upon the glottis”) is a cartilaginous lid, which closes the opening (the glottis) of the larynx during deglutition (swallowing). It has the form of a leaf, broadest at the top, and attached by its stem to the inner surface of the thyroid cartilage in front. During respiration it is nearly vertical, with its upper free extremity curving forward toward the base of the tongue; but during the act of swallowing, the larynx is drawn upward beneath the base of the tongue, so as to carry the epiglottis backward and downward, and completely close the glottis (the aperture in the larynx between the vocal cords).* 398 ORGANS OF VOICE AND RESPIRATION. The glottis (signifying the “mouth-piece of a flute”) is an oblong aperture, always narrow in front, but wider or narrower behind, as may be necessary to modify the voice. It is nearly an inch (two and one- half centimeters) in length in the male, but shorter in females and children, whose voices are on a higher key. The glottis, or rima glottidis (chink of the glottis) is the interval between the vocal cords. Fig. 283. THE GLOTTIS DILATED. There are two sets of vocal cords,— upper and lower, or false and true. The false vocal cords are the upper. They are two folds of mucous membrane inclosing a delicate ligament (the superior thyro-arytenoid), which runs parallel with the true vocal cords, but somewhat above them, and is not directly concerned in the production of the voice. Between the upper and lower vocal cords, or false and true, is the ventricle (little cavity) of the larynx. Fig. 284. SHAPE OF THE GLOTTIS WHEN AT REST. The lower, or true vocal cords are also called the inferior thyro- arytenoid ligaments (because each connects the thyroid cartilage in front with the arytenoid behind). Each cord consists of a band of yellow elastic tissue, covered by a thin layer of mucous membrane, so that the cords are not bare, like the strings of an instrument, but veiled by a fold of mucous membrane, that leaves an aperture (the glottis) only between the cords. ORGANS OF VOICE AND RESPIRATION. 399 The larynx has in all eight intrinsic muscles,— five of the glottis and three of the epiglottis,—all taking their names from the cartilages to which they are attached. Those of the glottis are the crico-thyroid, crico-arytenoid (lateral), crico-arytenoid (posterior), arytenoid, and thyro-arytenoid ; and those of the epiglottis are the thyro-epiglottic (the usual name is “thyro-epiglottideus ”), lower aryteno-epiglottic and upper aryteno-epiglottic (or aryteno-epiglottideus superior). The crico-thyroid muscles tighten and elongate the vocal cords, by drawing down the thyroid cartilage over the cricoid. The lateral crico- arytenoid muscies close the glottis, by rotating the base of the arytenoid cartilages inward, so as to approximate the posterior extremities of the Fig. 285. GLOTTIS, CLOSED, AND MUSCLES CLOSING IT vocal cords. The posterior crico-arytenoid separate the vocal cords (open the glottis), by rotating the base of the arytenoid cartilages out- ward. The arytenoid (a single muscle) assists the lateral crico- arytenoid, by approximating the arytenoid cartilages by direct action. It closes the glottis. The thyro-arytenoid muscles shorten and relax the vocal cords, by drawing the arytenoid cartilages forward. The upper aryteno-epiglottic muscles constrict the superior aperture of the larynx during deglutition. The thyro-epiglottic and lower aryteno-epi- glottic muscles depress the epiglottis, and compress the sacculus laryn- gis (or laryngeal pouch). The latter is a membranous sac, placed above the true vocal cords, into which open sixty or seventy small glands, that secrete a fluid intended to lubricate the vocal cords. The sac is a prolongation of the ventricle of the larynx. The nerves which supply the larynx are branches of the pneumo- gastric and sympathetic. The special branches of the pneumogastric are the superior and inferior laryngeal nerves. The inferior laryngeal is also called the recurrent laryngeal, on account of its direction. The latter supplies nearly all the muscles of phonation (action, or use of the voice). THE URINARY ORGANS. The urinary organs comprise the kidneys, ureters, bladder, and urethra. The two kidneys secrete the urine ; the ureters convey it to the bladder, which is a reservoir, situated and protected from undue compression, within the bony pelvis; and the urethra discharges the secretion from the body. The kidneys (Greek, “nephroi”) are situated, on either side, at the back part of the abdominal cavity, above the posterior crest of the ilium, partly in the hypochondriac region, and partly in the lumbar, and in front of the posterior portion of the eleventh and twelfth ribs. The right kidney is usually a little lower than the left, on account of its vicinity to the liver, the greater part of which lies in the right side of the body. The left kidney is usually the larger. In shape, the kidney resembles the kidney bean, the eye of the bean corresponding to the hilum of the kidney (hilum is properly the scar, or mark, left upon a seed at the place where the seed-stalk separates; it is the umbilicus of the seed). The hilum of the kidney is the notch, or fissure, on the inner concave border, where the blood-vessels, ureter, and nerves pass into and from the organ. The outer (or external) border of the kidney is convex, and directed outward, toward the walls of the abdomen. Each kidney is about ten centimeters (four inches) long, five centimeters (two inches) broad, and one or two centimeters (one inch) in thickness. It weighs about one hundred and fifty-five grams (five ounces), being larger in the male. The left is generally heavier by about eight grams. The kidney is covered by dense fibro-areolar tissue, which forms its capsule. At the hilum the capsule is continued inward, lining the sides of the sinus (or pelvis of the kidney), and at the bottom of the pelvis, or sinus, forms sheaths for the blood-vessels and branches of the excretory duct (the ureter). The pelvis, or sinus, occupies the interior of the kidney, and forms the tunnel-like expansion of the ureter as it enters the kidney. The pelvis at its widest part divides into three infundibula (tunnel-shaped cavities), and these in turn are sub-divided by papillary (nipple-like) projections into smaller cavities (called calices [cups]). THE URINARY ORGANS. 401 A vertical section of the kidney reveals two distinct portions of its substance,— the cortical (bark, or outer), and the medullary (central) portion. The central part, next to the pelvis, consists of ten or twelve Fig. 286. THE KIDNEYS, URETERS, AND BLADDER. conical-shaped bodies, which are termed the “ pyramids of Malpighi " (pronounced Mal-pe-ge, with the “g” hard). The bases and sides of the bodies are surrounded by the cortical substance ; their apices pro- ject into the calices (cups) at the margin of the pelvis, and are called Fig. 287. SECTION OF THE KIDNEY AND SUPRA-RENAL CAPSULE. Fig. 288. SECTION OF THE KIDNEY. i. The Ureter. 2. Pelvis of the Kidney. 3. Papillae. THE URINARY ORGANS. 403 papillae (or papillary projections). Each pyramid consists of a large number (estimated at one thousand) of diverging tubules (little tubes), bound together by fibrous tissue containing blood-vessels. These tubules of the pyramids are the tubuli uriniferi (urine-bearing tubes) of the kidney. They open by thousands of minute orifices at the surface of the papillae into the cups (calices) of the infundibula. The cortical substance consists of small, reddish corpuscles (little bodies) and convoluted tubules, imbedded in a fibrous stroma (bed), which contains vessels and nerves. The convoluted tubules are con- tinuous with the tubuli uriniferi of the pyramids. The corpuscles of the cortical substance are termed Malpighian bodies, or glomeruli (little balls). Two distinct offices are assigned to the corpuscles and tubules. The corpuscles act as filters, while the epithelium, which Fig. 289. Fig. 290. a. Artery. V. Vein, or Efferent Vessel. c. Capsule. d. Urinary Tube. MINUTE STRUCTURE OF THE KIDNEY, lines the tubules, is composed of secreting cells. The cells which line the tubules and corpuscles are nucleated. Each Malpighian corpuscle is composed of a capsule, and an inclosed tuft of blood-vessels and capillaries. The blood-vessels that enter the corpuscles are branches of the renal artery. The efferent (outward bearing) vessels of the corpuscles make up the veins. The nerves of the kidney are derived from the renal plexus, which is formed by filaments from the solar plexus and lesser splanchnic nerve — all being branches of the sympathetic system. The ureter is a membranous tube extending from the kidney, on either side, to the lower part of the bladder. It is about forty centi- meters (sixteen inches) in length, and of the size of a goose-quill, and forms the excretory duct of the kidney. In its course from above, downward, it rests upon the psoas muscle, behind the peritoneum. It 404 THE URINARY ORGANS. Fig. 291. THE BLADDER AND URETHRA LAID O^EN. passes obliquely downward and inward, enters the cavity of the pelvisr pierces the outer coats of the bladder, runs obliquely between its outer and inner coats for two or three centimeters (nearly an inch), and opens at the posterior angle of the trigonum (the triangular THE URINARY ORGANS. 405 space between the orifices of the two ureters and the urethra), about five centimeters (two inches) from its fellow of the opposite side. The ureter is composed of three coats — fibrous, muscular, and mucous. The mucous coat is continuous with that of the bladder. Fig. 292. THE BLADDER AND URETHRA LAID OPEN. The bladder is a reservoir for the urine until the accumulation of a ‘Certain quantity in the bladder solicits and procures its expulsion from the body. The bladder is situated in the hypogastric region, between the pubes and rectum, in the male ; but in the female the vagina inter- venes between the bladder and rectum. It is a musculo-membranous 406 THE URINARY ORGANS. sac, and when moderately distended contains two hundred and thirty- six cubic centimeters (half a pint) or more. The shape, position, and relations of the bladder vary with age, and the degree of distension. During infancy it is conical in shape, and projects above the upper border of the pubes. In the adult, when empty and contracted, it is triangular, and placed more deeply in the pelvis. When slightly distended it has a rounded form, and partially fills the pelvic cavity; when greatly distended it is egg-shaped, and rises above the pelvis into the abdominal cavity, so as to be plainly felt above the pubes. The upper part of the bladder is called the summit, or apex, and is attached to the umbilicus by a suspensory ligament called the urachus. In some animals the urachus is a membranous canal, which arises from the bladder, makes its exit from the abdomen at the umbilicus, and terminates during foetal life in the allantois (the allantois is a sort of elongated bladder, formed between the two membranes [the amnion and chorion] that surround the foetus). Occasionally the urachus has been found pervious at birth, so that the urine escapes at the umbilicus ; but this is a malformation. The summit of the bladder inclines forward toward the umbilicus, or some point between that and the pubes. The part opposite the sum- mit is called the base, or fundus (bottom) of the bladder. The base of the bladder rests, in the male, upon the second portion of the rectum ; in the female, upon the neck of the uterus (cervix uteri) and the anterior wall of the vagina. The neck of the bladder is the narrow, constricted portion at the commencement of the urethra, which is the excretory duct from the bladder. The bladder is held in place by ligaments,— five true and five false. The latter are formed by folds of peritoneum. The ten ligaments are two anterior, two posterior, four lateral, and two superior. The five true ligaments are the two anterior, two lateral, and one superior (the urachus). The ligaments connect the bladder to the prostate gland, rectum, uterus of the female, pubes, sides of the pelvis, and to the umbilicus. The posterior ligaments contain the obliterated hypogastric, or umbilical arteries of the foetus. The superior false ligament is a fold of peritoneum, which covers the urachus (the superior ligament) from the summit of the bladder to the umbilicus. The bladder has four coats,— serous, muscular, alveolar (this coat is often called cellular), and mucous. The serous coat is partial only, since the peritoneum does not invest the anterior surface of the bladder. The areolar coat connects the muscular and mucous coats. The mucous THE URINARY ORGANS. 407 coat is thin and smooth, and provided with a few mucous follices. The epithelium covering it is intermediate in form between the columnar and pavement varieties. Upon the inner surface of the base of the bladder is a triangular, smooth surface between the openings, or orifices, of the two ureters and the urethra, which is called the trigonum vesicse (triangle of the blad- der). Its apex is upward and forward, toward the urethra. The triangle lies in intimate relation with the rectum, and it is in this space that puncture of the bladder through the rectum is sometimes performed. Fig. 293. VERTICAL SECTION OF THE BLADDER, PENIS, AND URETHRA. The urethra is the common urinary canal; and in the male, is also the common spermatic canal. It extends from the neck of the bladder to the meatus urinarius (urinary passage). It is about twenty-one centimeters (eight or nine inches) long in the male, but less than five centimeters (two inches) in the female, and forms a curve beneath the arch of the pubes, with the concavity directed upward. In the female this curve is slight, as the urethra lies embedded in the anterior wall of the vagina; but in the male it is considerable, so that the male 408 THE URINARY ORGANS. catheter (an instrument for drawing off the fluid contents of the blad- der) is introduced with more difficulty. Its diameter when undilated is about six-tenths of a centimeter (one quarter of an inch). The female urethra admits of considerable dilatation, so that calculi (stones, or con- cretions), or other foreign substances, are removed from the female bladder with greater facility. The male urethra is divided into three portions,— the prostatic, membranous, and spongy. The prostatic portion is next to the blad- der, and is surrounded by the prostate gland. It is about three centi- meters (one and one-quarter inches) in length. The membranous portion extends from the prostate gland to the bulb of the corpus spongiosum (spongy body) at the root of the penis. It is one or two centimeters (half an inch, or more) in length, and is surrounded by the compressor urethrae (compressor of the urethra) muscle. The spongy portion of the male urethra is contained in the corpus spongiosum (spongy body) of the penis, and is about fifteen centimeters (six inches) in length. It extends from the membranous portion to the meatus urinarius (urinary passage), at the extremity of the glans penis. The urethra is lined with mucous membrane, which is continuous with the mucous membrane of the bladder, ureters, and kidneys. The supra-renal capsules are usually described with the urinary organs, but their use is unknown. They are situated, one on either side, immediately in front of the upper end of the kidney ; hence their name. In some individuals they are very small, in others, large. They are generally four centimeters (one and one-half inches) in length, a little less in width, and one centimeter (one quarter of an inch) in thickness. They are sometimes called atrabiliary (black bile) capsules, because believed by Galen and some other ancient physicians to be con- cerned in secreting black bile, and causing melancholy (black bile) and mania. They are now supposed to be connected with the sympathetic system. They are larger in the foetus than in the adult, and have no excretory duct. MALE GENITAL ORGANS. The principal male genital organs are the testes and penis. To these are generally added the prostate, and Cowper’s glands, and the vesiculae seminales. The principal male genital organs are external, while those of the female are internal; yet both are, in part, internal. The seminal vesicles of the male are deeply situated in the pelvis, behind the bladder, and the excretory duct of the testis (or testicle) enters the abdomen through the inguinal canal, and passes through the pelvis, behind the bladder, to reach the urethra, through which the seminal fluid is discharged. The greater part of the excretory duct of the testis is called the vas deferens (outward bearing vessel, or, more literally, “ vessel bearing from ”),— a name which is entirely inappropriate to the first part of its course, which is inward from the testicle to the abdomen and pelvis. At the neck of the bladder, where its course is truly outward, and where it unites with the duct of the seminal vesicle (vesicula seminalis), it takes the name of the ejaculatory duct. The name, “vas deferens,” is appropriate with reference to the testis {from which it bears the semen), but not with reference to the body. The prostate (standing before) gland surrounds the neck of the bladder and first part (prostatic) of the urethra. In shape and size it resembles the horse-chestnut. It can be distinctly felt, especially when enlarged, as it often is in old age, through the rectum. It consists of three lobes, as usually described — two lateral and a middle lobe. The third lobe is not constant, but is occasionally found at an early period of life. The third (or middle) lobe is situated between the two lateral, at the under and back part of the organ. The prostate gland is perforated by the urethra and by the ejaculatory ducts, which open into the prostatic portion of the urethra. The gland itself has fifteen, or twenty, excretory ducts, which also open into the prostatic portion of the urethra. The fluid discharged from the prostate, by aid of muscular bands around the organ, not only lubricates the in- terior of the urethra, but serves as a vehicle (or medium) for the sperm secreted by the testes. 410 MALE GENITAL ORGANS. Cowper’s glands are two small bodies, about the size of peas, placed beneath the membranous (second) portion of the urethra. Each has an excretory duct opening into the urethra. These glands diminish in size as age advances. THE TESTES. The testes (“witnesses,” because they give evidence of virility, or power of procreation) are the seminal glands of the male. They are two in number, one on either side, and are suspended by the spermatic cord in the scrotum, beneath the pubes — the left usually hanging a little lower than the right. The testes are also called “ testicles,” which is only the diminutive of testes. In the Greek, the word for testicle is didymis ; hence we have the word “ epididymis,” which signifies “ upon the testicle.” Fig. 2Q4* THE TESTIS IN SITU (IN POSITION) AS IT HANGS IN THE SCROTUM. Each testicle resembles in form and size a small hen’s egg. It is protected by several external coverings, which may be mentioned as the scrotum, spermatic fasciae, and tunica vaginalis; but each of these is divided into two layers. The two layers of the scrotum are the outer integument (the skin) and the dartos. The scrotum (signifying a “leathern bag”) is itself a cutaneous bag, or pouch, formed by a pro- longation of the skin of the inner part of the thigh, perinaeum, and penis, and containing the testes and lower portion of the spermatic. MALE GENITAL ORGANS. 411 cords. It is divided into two lateral halves by a median line, or raphe (suture or seam), which is continued along the middle line of the perineum. The scrotum is usually elongated and flaccid in old and debilitated persons; but in the young and vigorous, and especially under the influence of cold, it is short, and closely applied to the testes. The integument of the scrotum has a peculiar brown color, and is thrown into numerous rugae (wrinkles) when the scrotum is contracted. The dartos (skinned) is the contractile layer of the scrotum. It is very vascular, and contains involuntary muscular fiber. The dartos sends inward a prolongation (the “septum scroti”—partition of the scrotum), which divides the scrotum into two distinct cavities, one for each testis. The two layers of spermatic fasciae that cover the testes are the external and the internal spermatic fascia. The external spermatic fascia is also called intercolumnar (“between the pillars” of the exter- nal abdominal ring) fascia; and the internal is also called infundibuli- form (“funnel-shaped,” from the internal abdominal ring), or fascia propria. The tunica vaginalis (sheath-covering), like other serous mem- branes, consists of a parietal and a visceral layer. The visceral por- tion covers the outer surface of the testis, while the parietal portion lines the inner surface of the dartos, or scrotum. The tunica vagi- nalis is really a prolongation of the peritoneum in the foetus ; but after birth the connection of the scrotum with the abdomen through the inguinal canal becomes obliterated, and the scrotum becomes a shut sac. The interval between the two layers of the tunica vaginalis con- stitutes the cavity of the tunica vaginalis, and is the seat of hydrocele (watery tumor). In addition to these six external coverings of the testicle, authors usually mention another — the cremaster (suspender) muscle, which consists of scattered bundles of muscular fibers, and is hardly worthy of mention as a covering. Its office is to draw up the testicle. In order to a better understanding of the external coverings of the testis, it is necessary to mention that the testis is first formed in the abdomen, behind the peritoneum, and just before birth descends through the inguinal canal into the scrotum, carrying before it numer- ous coverings derived from the serous, muscular, and fibrous layers of the abdominal walls. The testis is believed by some to be drawn downward from the abdomen by a cord, called the gubernaculum testis (governor of the testis), which extends from the testis to the scrotum and ischium. Besides its seven external coverings, the testis itself has two other 412 MALE GENITAL ORGANS. coats (or tunics). These are the tunica albuginea (white coat) and tunica vasculosa (vascular coat). The white coat is fibrous. It gives shape and firmness to the testicle. The vascular tunic consists of a plexus of blood-vessels, held together by delicate areolar tissue, and covers the inner surface of the tunica albuginea. At the posterior and upper border of the testicle (or testis) the tunica albuginea (the white, fibrous coat) is reflected into the interior of the gland, forming an incomplete vertical septum, called the medias- tinum testis (middle space of the testis). Fig. 295. VERTICAL SECTION OF THE TESTIS, OR TESTICLE. The interior of the gland consists of a great number of little lobes (lobules), each of which contains a few small, convoluted tubes (tu- bules), called tubuli seminiferi (seed-bearing tubes). The total num- ber of these tubes is variously estimated, varying from 300 to 62,500; and their total length from 1,890 feet to 5,208 feet. Toward the pos- terior part of the gland the tubes become less convoluted, and by unit- ing, form twenty to thirty larger ducts, which, on account of their straight course, are called vasa recta (straight vessels). The straight ducts enter the mediastinum, and pass upward, forming in their ascent a close network of tubes, called the rete testis (net of the testis). At the upper end of the mediastinum the vessels, or ducts of the net, ter- MALE GENITAL ORGANS. 413 minate in fifteen or twenty ducts (the vasa efferentia, or outward bear- ing vessels), which perforate the white coat of the testis, and carry the seminal fluid to the epididymis (upon the testis). The epididymis consists of a convoluted tube twenty feet long or more, which by its complex convolutions forms the body of the epididymis. This body extends along the upper and posterior margin of the testicle, held in place by fine areolar tissue ; and at the lower end of the testicle, where it is called the globus minor (lesser globe), it opens into the vas defer- ens (vessel bearing from), which carries the seminal fluid upward through the inguinal canal into the abdomen and pelvis. The upper part of the epididymis is formed by the convolutions of the vasa effer- entia (efferent vessels), and is called the globus major (greater globe, or ball). Fig. 296. BASE AND POSTERIOR SURFACE OF THE BLADDER, SHOWING THE URETERS, SEMINAL DUCTS, AND SEMINAL VESICLES. The vas deferens forms a part of the spermatic cord till it enters the abdomen, then passes down into the pelvis behind the bladder, and uniting at the base of the bladder with the duct of the seminal vesicle forms the ejaculatory duct. The latter opens into the prostatic portion of the urethra. The spermatic cord extends from the testis below to the internal abdominal ring (the inner orifice of the inguinal canal). It is com- posed of the vas deferens, which is one portion of the excretory duct of the testis, of arteries, veins, lymphatics, and nerves, all connected by areolar tissue, and invested by their proper coverings. 414 MALE GENITAL ORGANS. The arteries of the cord are the spermatic from the aorta, the artery of the vas deferens from the superior vesicle, and the cremasteric from the epigastric artery. The spermatic artery supplies the testicle. The nerves are derived from the sympathetic. The seminal vesicles (ve- siculae seminales) are two lobulated membranous pouches placed be- hind the bladder, between it and the rectum, and serve as reservoirs for the semen, like the gall bladder for the bile. They are six or seven centimeters (two and one-half inches) long, and one or two centime- ters (one half inch) in breadth, but vary in size in different individu- als. Each vesicle consists of a single tube, coiled upon itself, and held in place by fibrous tissue. When uncoiled this tube is about the diam- eter of a quill, and from ten to fifteen centimeters (four to six inches) long. It terminates posteriorly in a cul-de-sac (no opening), but its anterior extremity forms a narrow, straight duct, which unites with the vas deferens of the same side to form the ejaculatory duct. The latter passes forward and upward in the substance of the prostate gland one or two centimeters (three fourths of an inch), and opens into the urethra, which is thus made to form the final portion of the excretory duct of the testis. The semen (seed), or sperm, is a thick, whitish fluid, which is se- creted in part by the testes and in part by the prostate gland. It con- tains seminal granules and spermatozoa, or zoosperms (sperm-animals). The zoosperms are the essential agents in producing fecundation (or fruitfulness). They are minute, elongated particles with a long, slender caudal filament, resembling in shape and motion the tadpole. Such is the apparent beginning of human life. THE PENIS. The penis (tail) is the organ of copulation. It is situated in the median line of the body, in front of the pubic arch, and consists of a root, body, and extremity, or glans (signifying “acorn,” from its shape). The root is attached by two strong, fibrous processes to the rami (branches) of the pubis, and by a fibrous membrane to the front of the symphysis pubis. At the extremity of the glans is the orifice of the urethra (the meatus urinarius). The base of the glans forms a rounded border, called the corona glandis (crown of the glans). The body is the part between the glans and the root. The body is covered with integu- ment, which at the root is continuous with that which covers the pubes; but at the crown leaves the surface, and becomes folded upon itself, so as to form the prepuce (foreskin), which was, among some nations, re- moved by circumcision (cutting around). MALE GENITAL ORGANS. 415 The prepuce is attached to the lower part of the meatus urinarius (urinary passage), and forms the frenum (bridle). The body of the penis consists of three portions, or three fibrous compartments, which, when distended with blood, give the form of a triangular prism with rounded angles, but in the flaccid condition the organ is cylindrical. The three compartments are named the spongy body (corpus spongi- osum) and the two cavernous bodies (corpora cavernosa). The two latter lie side by side along the upper surface, or dorsum (back) of the penis, while the spongy body runs forward beneath the two cavernous bodies, and expands into the glans, or head, which covers the ends of the cav- ernous bodies. The spongy portion contains the urethra, which con- veys the semen tp the meatus urinarius (urinary passage). These three bodies are composed of erectile tissue. The spongy body terminates near the root of the penis, in what is called the bulb, which varies in size in different subjects. Erectile tissue consists of a great number of anastomosing veins. The superficial lymphatic vessels of the penis terminate in the inguinal glands; the deep lymphatics pass beneath the pubic arch, and enter the pelvis. FEMALE GENITAL ORGANS. The principal genital organs of the female are the ovaries, uterus, or womb, and the mammae (breasts). The ovaries and uterus are* internal; the mammae, external. To these—the principal organs—must be added, for a full description, the vagina (sheath) and the volva (fold of integument, from volvo, “to roll,” more frequently written “vulva”). The mons Veneris (mount of Venus) is the eminence which sur- mounts the volva, and at puberty becomes covered with hair. The labia (lips), larger and smaller, are folds of integument inclos- ing the common urino-sexual opening. The more external folds are called the labia majora, and the internal, labia minora, or nymphae. (Nympha signifies a spouse, or bride.) Sometimes the greater and sometimes the lesser lips are most prominent. • The anterior and posterior commissures are the extremities of the common fissure, or opening. The clitoris is a small erectile organ, situated just within the ante- rior commissure. Between the clitoris and the entrance of the vagina is a triangular smooth surface, between the nymphae, called the vesti- bule. Within the vestibule, and near the anterior margin of the vagina, is the orifice of the urethra (meatus urinarius). Below the vestibule is the orifice of the vagina (sheath), which leads to the os uteri (mouth of the uterus). • In early life the vagina is usually more or less closed by a membra- nous fold, called the hymen (god of marriage). The hymen sometimes forms a complete septum across the orifice of the vagina, and consti- tutes an imperforate hymen. In other cases it is circular, with a small opening in the center, or, it may be, stretched across the lower part only of the orifice, and may be entirely absent. The vagina (sheath) is a canal extending from the volva to the uterus, or womb. It is about twelve centimeters (five inches) in length, being somewhat curved, and longer on its posterior border. It surrounds, or embraces, the lower portion of the neck of the uterus (cervix uteri), and gives exit and entrance to the womb. It has a mus- cular coat, a layer of erectile tissue, and an internal mucous lining. At FEMALE GENITAL ORGANS. 417 the commencement of the vagina on each side is an oblong body (the gland of Bartholine), which is analogous to Cowper’s gland in the male. It has an excretory duct opening upon the inner side of the nympha. The uterus (metra) is the organ of gestation. It is situated in the pelvis between the bladder and rectum, and resembles, in shape and size, a flattened pear. The broader, upper portion is called the fundus (bottom); and the lower, contracted portion, the neck (cervix). The neck projects partly into the vagina, and forms the mouth of the uterus (os uteri), which is the external orifice of the uterine cavity. The cavity also communicates with the two Fallopian tubes (or oviducts). The uterus is held in place by folds of peritoneum, which connect it with the bladder, rectum, and sides of the pelvis; and, also, by two true ligaments (the round), which extend from the superior angle of the uterus, on either side, through the inguinal canal, to the labia majora Fig. 297. THE UTERUS AND ITS APPENDAGES. (greater lips). The folds of peritoneum that serve as uterine ligaments are six in number,— two broad ligaments, two anterior, and two poste- rior. The anterior connect with the bladder, the two posterior with the rectum, and the two broad ligaments with the walls of the pelvis. The latter (the broad ligaments) invest the body of the womb, as the mesen- tery does the bowel, and extending outward to the sides of the pelvis, inclose, separately, the round ligaments, the ovaries and Fallopian tubes, and form a septum across the pelvis in front of the rectum. The tubular process of the peritoneum (or broad ligament), which incloses the round ligament as it passes through the inguinal canal, has been called the canal of Nuck (Antony Nuck), although it is seldom a distinct canal, except in the foetus. 418 FEMALE GENITAL ORGANS. The broad ligament forms the external serous coat of the uterus; the middle coat, which forms the bulk of the substance of the uterus (or womb), is muscular, and the internal is a mucous coat. During gestation (or pregnancy) the muscular coat becomes more prominently developed, and the womb constantly increases in size till near the period of parturition (labor, or delivery). The mucous mem- brane extends into the Fallopian tubes (oviducts), and at their fimbri- ated (fringed) extremity becomes continuous with the peritoneum ; and Fig. 298. SECTION OF THE FEMALE PELVIS, SHOWING POSITION OF VISCERA. through the os uteri, the mucous membrane is continuous with the lining of the vagina. The mucous membrane is lined with columnar ciliated epithelium. The cervix (neck) of the womb is provided with mucous follicles, and some glands (the glands of Naboth). The arteries of the uterus are the uterine and ovarian, derived, respectively, from the internal iliac and aorta. They are remarkable for their tortuous course, which is a provision for the change which takes place in the size of the organ during gestation. The veins are of FEMALE GENITAL ORGANS. 419 large size, and correspond with the arteries. In the gravid (heavy) uterus the veins are termed uterine sinuses. The ovaries and Fallo- pian tubes are generally described as appendages of the uterus; but it would be more correct to speak of the Fallopian tubes and uterus as appendages of the ovaries, since the ovaries represent the bird that lays the egg ; while the uterus is only the nest where the egg is hatched. The ovaries (egg-producers) are two bodies somewhat analogous to the testes of the male. They are situated one on each side of the uterus, are inclosed by the broad ligament, and connected to the uterus by a proper ligament (ligament of the ovary), and to the fimbriated extremity of the Fallopian tube by a short cord. The ovaries are somewhat smaller than the male testes. The proper covering of the organ is a dense, firm, fibrous coat (the tunica albuginea), which incloses a soft, fibrous tissue abundantly supplied with blood-vessels. Imbeded in the meshes of this tissue, and composing the main sub- stance of the ovary, are numerous small, round, transparent vesicles Fig. 299. SECTION OF THE OVARY. (the Graafian vesicles), in various stages of development. These Graafian vesicles are the ovisacs which contain the ova (eggs). The matured vesicles are found near the surface of the ovary, ready to burst through, like a plant through the surface of the ground. The ovum (egg), in a perfectly matured vesicle, measures about one one-hundred and twentieth of an inch in diameter. Liberated from the ovary by the periodical bursting of one or more Graafian vesicles, the ovum is taken up by the fimbriated (fringed) extremity of the Fallo- pian tube and conveyed to the interior of the uterus, where it remains for a few days, and then, when unimpregnated, passes through the cer- vix and os uteri into the vagina, as an excretion ; but when fecundated in the uterus by the male sperm, or spermatozoid, it becomes attached to the inner surface of the womb, and is called the embryo. The Fal- lopian tube (Gabriel Fallopius) is about ten centimeters (four inches) in length. Its canal is very minute, and will scarcely admit a fine bristle. One on each side extends from the superior angle of the 420 FEMALE GENITAL ORGANS. uterus to the free margin of the broad ligament. The maturing of an ovum and the rupture of a Graafian vesicle at the surface of the ovary, is recorded upon the ovary by the appearance of a scar, or yellow spot, which has been called the “corpus luteum’’ (yellow body),— and some have affirmed that the impregnation of the ovum materially changes the character of the corpus luteum ; but this assumption is no more probable than the erroneous belief that the absence of the hymen is evidence of the loss of virginity. THE MAMMAE (Breasts). The mammae are the glands that secrete the milk. In the male they are usually rudimentary, but in some instances are said to have been developed. They are two large eminences, one on either side, beneath the integument, external to the great pectoral muscle (pecto- ralis major), and separated only by a layer of fascia. Their weight and dimensions differ in different individuals and at different periods of life. They enlarge at puberty, during pregnancy, but more especially after delivery, and become atrophied (wasted), as a gland, in old age. The nipple (or teat) is a conical, erectile eminence upon the summit of the gland where the numerous lactiferous (milk-bearing) ducts all termi- nate. The nipple itself is dark-colored, and is surrounded by a colored circle, called the areola (little space). In the young virgin the areola has a delicate pink, or rosy hue ; after impregnation it acquires a darker tinge, usually a dark-brown color. The mammary gland consists of numerous lobes and lobules (small lobes), connected by areolar tissue, blood-vessels and ducts. The lobules consist of a cluster of vesicles, which open into the lactif- erous ducts. The number of excretory ducts varies from fifteen to twenty. They are termed the tubuli lactiferi (milk-bearing tubes). These tubes converge toward the center of the breast, and beneath the areola form dilatations, which serve as reservoirs for the milk ; but at the base of the nipple they become contracted again, and pursue a straight course to its summit, where they open by several small orifices. Fatty tissue surrounds the surface of the gland, and occupies inter- vals between its lobes ; and it is the fatty tissue which largely deter- mines the form and size of the mammae. The arteries are derived from the thoracic branches of the axillary, the intercostals, and the internal mammary. The lymphatics of the mammae terminate in the axillary glands. Fcetal Circulation. The foetal circulation differs materially from that of the adult, chiefly because the blood is not aerated in the lungs till after birth. The arte- rial blood, for the nutrition of the foetus, is brought from the placenta of the mother along the umbilical cord, by means of the umbilical vein, and is carried directly to the liver, which in the foetus is, proportionally, very large. At the liver a portion of the blood is distributed directly to that organ, a portion enters the liver mixed with the blood from the vena portae, and a third portion passes through a canal peculiar to the foetus (the “ ductus venosus,” or venous duct), directly into the vena cava, which carries the blood to the right side of the heart. At the right side of the heart the blood from the inferior vena cava is guided by the Eustachian valve, which is peculiarly developed, through an opening (the “foramen ovale”) peculiar to the foetal heart, directly into the left auricle, without passing through the lungs, as it does in the adult ; whilst the blood from the superior vena cava descends over the Eustachian valve into the right ventricle. From the right ven- tricle the blood enters the pulmonary artery; but instead of going to the lungs in any considerable quantity, the greater part passes through a canal, or duct (the ductus arteriosus, or arterial duct) peculiar to the foetus, directly into the descending aorta, where it unites with a small quantity of blood transmitted from the left ventricle. The greater part of the arterial blood from the placenta, mixed with the blood from the inferior vena cava, reaches the arch of the aorta through the ductus venosus, foramen ovale, and left ventricle of the heart, and is distributed to the head and upper extremities, which are proportionally large and well developed at birth ; while a small portion is carried, by the descend- ing aorta, to the abdomen and lower extremities. The greater part of the blood transmitted by the descending aorta to the internal iliac arteries is venous blood, on its way back to the placenta, which it reaches by means of two vessels (the umbilical, or hypogastric arteries) peculiar to the foetus, and which help to form the umbilical cord. The umbilical arteries arise from the internal iliacs, in addition to their usual branches, in the adult, ascend along the sides 422 FCETAL CIRCULATION. of the bladder of the foetus to the umbilicus, pass out of the abdomen, and coiling round the umbilical vein of the cord, reach the placenta. To sum up the principal peculiarities of the foetal circulation, we notice, first, the fact that the function of respiration is latent, the blood Fig. 300. PLAN OF THE FCETAL CIRCULATION. FCETAL CIRCULATION. 423 of the foetus being aerated in the lungs of the mother, and reaching the foetus through the placenta and the umbilical vein of the umbilical cord; second, that the arterial and venous blood are less distinct (more freely mingled) than in the adult; and, third, a difference in the anatomical structure of the vascular system. Fig. 301. ANOTHER VIEW OF THE FCETAL CIRCULATION. The principal anatomical peculiarities are, first, the existence of the foramen ovale, which opens direct communication between the right and left sides of the heart; second, the peculiar development of the Eustachian valve, which turns the current of blood from the inferior vena cava directly into the left side of the heart; third, the ductus arteriosus (a short tube about one centimeter [one half inch] in length), which connects the left branch of the pulmonary artery with the arch of the aorta; fourth, the umbilical, or hypogastric arteries, which 424 FCETAL CIRCULATION. extend from the internal iliacs along the umbilical cord to the placenta; and, fifth, the ductus venosus, which opens communication between the umbilical vein and inferior vena cava. At birth, the pressure of the atmosphere inflates the lungs ; the placental circulation is cut off in the umbilical cord ; the blood from the pulmonary artery passes through the lungs ; the ductus arteriosus begins immediately to contract, and in a few days becomes completely closed, but remains as a cord to connect the pulmonary artery to the arch of the aorta; the foramen ovale becomes gradually closed about the tenth day after birth ; the umbilical arteries, between the third and fifth days, become obliterated, and form the anterior, true ligaments of the bladder ; and in about the same time the umbilical vein and ductus venosus become obliterated, the umbilical vein becoming the round ligament of the liver, and the ductus venosus a fibrous cord connecting the liver with the inferior vena cava. SURGICAL ANATOMY The word surgery is a contracted form of the obsolete word chirar- gery, and signifies “hand-work,” or manual operations. A distinguished surgeon of France declared that operations were the “opprobrium of surgery;” and an equally distinguished physician of England declared, “ It is our ignorance that renders operations nec- essary.” Doubtless but for ignorance, the entire healing art would become obsolete, or be merged in a general and universal education. The “ setting,” or adjusting of broken bones and dislocations belongs to surgery; but surgical anatomy treats only of the strticture of farts of the body where manual operations are more frequently required. Of surgical anatomy, the most important parts are those that relate to hernia (the protrusion of some viscus, or part, from its natural cavity); the tying of arteries ; the removal of tumors, foreign bodies, and calculi (stones, or concretions); and the making of artificial openings for the introduction of air to the lungs, or for the escape of some superabun- dant secretion, or undue accumulation of waste-matter within some cavity or part of the body. The principal parts embraced in surgical anatomy, are the inguinal regions, Scarpa’s triangles, the triangles of the neck, the axillary space, the popliteal space, the perinaeum, the abdominal and pleural cavities, the nasal passages, pharynx, and larynx. In the inguinal regions, we find the inguinal and femoral canals, which are frequently the seat of hernia ; in Scarpa’s triangle, we find the femoral artery, and other large blood-vessels and nerves of the lower extremity; in the triangles of the neck, we find large and impor- tant blood-vessels and nerves that pass to and from the head and upper extremities ; in the axillary space, vessels and nerves to the upper extremity; in the popliteal space, vessels and nerves to the leg and foot; in the perinaeum we find access to the rectum and bladder ; the abdominal (or peritoneal) and pleural cavities are frequently the seat of dropsical effusion ; the nasal passages and pharynx are liable to be obstructed by foreign bodies and abnormal growths ; and the larynx 426 SURGICAL ANATOMY. and trachea are sometimes opened artificially for the introduction of air. For the benefit of the general reader we shall speak briefly of some of these parts, and refer medical students, for a more minute description, to the body of this work and treatises on surgery. The word hernia signifies a sprout, or shoot, and is applied to the protrusion of any internal organ, or part, from its natural cavity. The three great cavities are those of the skull, chest, and abdomen. A pro- trusion of the contents of the skull and chest is somewhat rare, but abdominal hernia is more common. The latter is divided, according to the aperture by which the hernia escapes, into inguinal (groin), fem- oral (thigh) and umbilical (navel) hernia. Fig. 302. INGUINAL CANAL AND SPERMATIC CORD. inguinal hernia is situated in the inguinal region, and may be direct, or oblique. An oblique inguinal hernia follows the course of the inguinal canal, which lies obliquely in the groin, leaving the abdomen at the internal abdominal ring (entrance to the inguinal canal), and protruding, beneath the skin, from the external abdominal ring (the outlet of the canal). SURGICAL ANATOMY. 427 Direct inguinal hernia does not escape through the internal abdom- inal ring and inguinal canal, but protrudes directly through the perito- neum (the firm membrane that covers the bowels beneath the skin) and the external abdominal ring. This form of hernia is rare. The inguinal canal lies obliquely in the groin, just above Poupart’s ligament, and nearly parallel with it. It is about one and one-half inches in length, and transmits the spermatic cord in the male, and the round ligament in the female. Inguinal hernia is more common in the male. The spermatic cord extends from the internal abdominal ring to the testicle. It is composed of the excretory duct of the testicle, arteries, veins, nerves, and lymphatic vessels. The cord is generally a little longer on one side than the other, so as to suspend one testicle a little lower than the other. The round ligament of the uterus extends from the superior part of the uterus to the labia majora. It consists of a bundle of fibrous tissue, together with muscular fibers, vessels, and nerves, and all inclosed in a fold of peritoneum. Poupart’s ligament (called, also, the “crural arch”) is a part of the aponeurosis (flattened tendon) of the external oblique muscle, and is continuous with the fascia lata (broad bandage) of the thigh. The external abdominal ring is not a ring, but a triangular interval in the aponeurosis of the external oblique muscle, but becomes more or less oval when distended by a hernia. The two sides of the triangular interval (called the external abdominal ring) are formed by the two “pillars of the ring,” and its base by the pubic bone. The two pillars (called also “ columns ” by some authors) of the external ring are bound together above by a set of aponeurotic fibers, which constitute the intercolumnar (between the columns) bands from which is derived a covering (called the intercolumnar, or external spermatic, fascia) for the emerging cord. The internal abdominal ring is bounded above and externally by arched fibers of the transverse muscle, and beneath the arch is the sprout-like prolongation of the transversalis fascia (the infundibuliform) which invests the cord. This fascia (the infundibuliform, or transver- salis) extends from the margin of the internal ring, and forms the fifth layer of all inguinal herniae (plural of hernia). It incloses the cord and testicle (or testis) in a distinct pouch. By placing the finger in the external abdominal ring, it will be noticed that extension and abduction (carries the leg outward from the median line) of the leg renders the crural arch tense, and constricts the external ring. It will, therefore, be relaxed by flexion and adduction of the leg. 428 SURGICAL ANATOMY. The inguinal canal is formed between the time of birth and the age of puberty. At birth, the upper and lower openings of the foetal ring (corresponding to the internal and external abdominal rings of the adult) are opposite to each other, and scarcely separated; and the sper- matic cord of the infant runs in a straight line from the psoas muscle to the bottom of the scrotum, and passes through a mere aperture. As the foetal ring becomes changed into the adult canal (the inguinal), the internal orifice changes its position, and ascends toward the spine of the ilium, by the gradual extension of the transversalis fascia which incloses the cord in the canal. The passage of the testis (or testicle) through the inguinal canal usually takes place about the eighth month of intra-uterine life, but it may be delayed till months after birth. It may adhere to the colon, or abdominal wall, and it may be arrested in the inguinal canal, and be mistaken for hernia. The cremaster muscle consists of fibers derived from the internal oblique muscle during the descent of the testis. The two pillars, or columns, of the external abdominal ring are formed by the separation into two parts of the tendon of the external oblique muscle. In old hernias, the upper and lower orifices of the inguinal canal are sometimes brought opposite to each other by the absorption of the posterior side of the canal caused by pressure. In such cases the term oblique, or indirect, is no longer applicable. Unless distended by hernia, the inguinal and femoral canals are simply flattened passages. In foetal life, and, in many cases, for a month or so after birth, a tubular process of peritoneum extends from the internal ring to the bottom of the testicle. Before birth, or soon after, this vaginal (because it forms a sheath) process of the perito- neum becomes divided into two portions,— the superior (which incloses the cord), and the inferior, or vaginal process, which usually remains as a closed sac, covering the testicle throughout life. The superior por- tion of this process, peculiar to the spermatic cord, usually becomes obliterated, and its superior abdominal orifice permanently closed ; but the time of the closure of this ventral orifice is not fully determined. Paletta says it takes place from the twentieth to the thirtieth day after birth. In case of hernia into the vaginal process of the peritoneum before the closure of this canal, the intestine and testicle touch each other, and are contained in the same sac. Such hernia are called “congenital,” and it is impossible to raise in such cases the hernial sac, and leave the testicle in place, since the latter is also contained in the hernial sac. Femoral hernia is a protusion of some portion of the abdominal SURGICAL ANATOMY. 429 contents through the femoral canal. This canal is situated beneath Poupart’s ligament, while the inguinal canal is above it. It is a narrow interval on the inner side of the femoral vein, and is within the sheath (crural, or femoral sheath) that incloses the femoral vessels. It is a distinct canal only when the sheath has been separated from the vein by the pressure of a hernia, or tumor. It is a short canal, usually less than half an inch in length. Its upper opening leads into the cavity of the abdomen, and is called the femoral, or crural ring. Its lower opening in the fascia lata of the thigh is called the saphenous opening, (see Fig. 181) because it transmits the internal saphenous vein. The upper opening of the femoral canal is closed by the septum crurale (pronounced in three syllables), and the lower (the saphenous open- ing) is closed by the cribriform fascia. This fascia is called cribri- form, because it is pierced by numerous small blood-vessels. The coverings of inguinal and femoral hernia are somewhat differ- ent, yet they are all covered by the skin, superficial fascia, and perito- neal sac. In addition to these, femoral hernia has, also, as a covering, the sep- tum crurale, the femoral sheath, and the cribriform fascia, which are all peculiar to femoral hernia. In addition to the common coverings mentioned above, both forms of inguinal hernia have, also, the intercolumnar fascia, the fascia trans- versalis, and the sub-serous cellular tissue. Oblique inguinal hernia has, also, as a covering, the cremaster mus- cle ; and direct inguinal hernia the conjoined tendon of the internal oblique and transversalis muscles. The order of the coverings in all these hernias from without inward is as follows; viz., first, the skin; second, superficial fascia; third, in inguinal hernia (both forms) the intercolumnar fascia, and in femoral the cribriform fascia; fourth, in oblique inguinal hernia the cremaster muscle, in direct inguinal hernia the conjoined tendon of the internal oblique and transversalis muscles, and in femoral hernia the femoral sheath (fascia propria); fifth, in both forms of inguinal hernia the fascia tranversalis (or infundibuliform fascia), and in femoral hernia the septum crurale; sixth, in both forms of inguinal hernia the sub- serous cellular tissue, and in femoral hernia the peritoneal sac; and, seventh, in both forms of inguinal hernia the peritoneal sac. 430 SURGICAL ANATOMY. SCARPA’S TRIANGLE. This region of surgical anatomy (see Fig. 146) corresponds to a triangular depression in the groin, and is formed by Poupart’s ligament and the sides of two muscles (the sartorius and adductor longus). The floor of this space is formed by several muscles (iliacus, psoas, pectineus, and two adductors [longus and brevis]) ; and the space is covered by the skin, the fascia lata, and a portion of the sartorius muscle. The middle of this space is occupied by the femoral vessels (artery and vein). The femoral artery gives off in this space its cutaneous and deep branches, and the femoral vein receives the deep femoral and internal saphenous veins. The femoral vein lies in the upper part of the space at the inner side of the artery, and the anterior crural nerve (a very large nerve) lies about half an inch to the outer side of the artery ; or in, other language, the artery lies between the vein and nerve. The artery and vein lie in the same sheath, but are separated by a thin partition of fibrous tissue. At the lower part of the space the vein passes down behind the artery to the outer side. In this situation the femoral vessels may be easily compressed, or tied. THE POPLITEAL SPACE, OR HAM. This is behind the knee, and occupies the lower third of the thigh and the upper fifth of the leg. Above, it is limited by the opposition of the inner and outer hamstring muscles. The tendon of the biceps forms the outer hamstring, and the tendons of four muscles (the semi- membranosus, semitendinosus, gracilis, and sartorius) the inner ham- string. These muscles are supplied by the great sciatic nerve, and flex the leg upon the thigh. Below, the popliteal space is limited by the junction of the two heads of the gastrocnemius muscle. The floor of the space is formed by the posterior surface of the femur and tibia, the posterior ligament of the knee-joint, and the fascia covering the poplit- eus muscle, and the space is covered by the fascia lata and skin. The contents of the popliteal space (see Fig. 148) are the popliteal vessels (artery and vein), the termination of the external, or short saphenous vein, the popliteal nerves, the small sciatic nerve, small lymphatic glands, and loose adipose tissue. SURGICAL ANATOMY. 431 Fig- 3°3- THE AXILLARY SPACE, OR AXILLA (Armpit). The position of this space is sufficiently obvious. It is bounded by muscles (anteriorly by the pectoral muscles, and posteriorly by the sub- scapular, teres major, and latissimus dorsi), and covered by the skin and two muscles (the pectoralis major and subclavian). The axillary space contains the axillary vessels (an artery and vein), the brachial plexus of nerves, and a large number of lymphatic glands. The axillary artery (see Fig. 153) is a continuation of the subclavian, and takes its name at the lower border of the first rib, and terminates (changes its name to “brachial ”) at the lower border of the tendons of the latissimus dorsi and teres major muscles. Its direction varies with the position of the limb; when the arm hangs or lies by the side, the vessel forms a gentle curve with the convexity upward; when it is at right angles with the chest the vessel is nearly straight, and when uplifted, or elevated still more, the artery describes a curve again, but with the concavity directed upward. At its commencement the artery is deeply situated, but near its termination in the brachial is superficial, being covered only by the skin and fascia. 432 SURGICAL ANATOMY. The popliteal artery in the first part of its course rests on the inner surface of the femur, but below on its posterior surface. The vein is more superficial than the artery, but they are closely connected. TRIANGLES OF THE NECK. All points of the neck on one side have corresponding points on the other side, which are symmetrically disposed with respect to the vertical median line in front. For this reason one description answers for both sides. Now, on each side of the neck we have five triangles. Three of these are in front of the sterno-cleido-mastoid muscle, and two are behind it. (See Fig. 119.) The space in front of the muscle is called the anterior triangular space, and that behind is called thq posterior tri- angular space. The latter extends to the anterior border of the trape- zius muscle. Two other muscles (the omo-hyoid and the digastric) and the lower jaw also serve as boundaries. The omo-hyoid extends from the hyoid bone to the shoulder (to the upper border of the scapula). It has, like the digastric, two bellies, named, respectively, the anterior and posterior belly. It has also a central tendon, which is held in position by a process of the deep cervical fascia, which includes it in a sheath, and is attached to the cartilage of the first rib. The anterior belly is next to the hyoid bone, and in the upper part of its course is nearly ver- tical, while the posterior belly is more nearly horizontal. The digastric muscle extends, in a curved form, from the symphy- sis menti (the median line of the chin where the two sides of the jaw unite) to the side of the head, just behind the ear (to the mastoid proc- ess of the temporal bone), its central tendon being attached to the hyoid bone. Three of the triangles of the neck are named from contiguous bones,— the submaxillary, subclavian, and occipital; and two are named from the large artery of the neck,— the superior carotid and the inferior carotid. Their names and boundaries are as follows, viz.:— 1. Submaxillary: lower border of the jaw, median line of the neck, and posterior belly of the digastric muscle. 2. Superior carotid: sterno-mastoid, omo-hyoid, and digastric mus- cles. (Its posterior belly.) 3. Inferior carotid: middle line of the neck, sterno-mastoid, and omo-hyoid muscles. 4. Occipital: trapezius, sterno-mastoid, and omo-hyoid muscles. 5. Subclavian: sterno-mastoid, omo-hyoid muscles, and clavicle. SURGICAL ANATOMY. 433 The common carotid artery is found in the inferior carotid triangle, but extends into the superior carotid triangle, where it bifurcates. The external and internal carotid arteries and facial vessels and nerve are found only in the submaxillary and superior carotid triangles. The internal jugular vein and pneumogastric nerve are found in all the three triangles of the anterior space (space in front of the sterno- mastoid muscle). The recurrent laryngeal nerve, trachea, and thyroid gland are found only in the inferior carotid triangle. The larynx lies partly in each of the two carotid triangles. The superior thyroid artery and vein are found only in the superior carotid triangle. The lingual artery and vein are in the superior carotid triangle. The external jugular vein is in the sijbclavian triangle. The glosso-pharyngeal nerve, the temporal and internal maxillary artery and vein, and the parotid and submaxillary glands, are in the submaxillary triangle. In the superior carotid triangle the carotid arteries are somewhat concealed from view by the edge of the sterno-mastoid muscle which overlaps them. The external and internal carotids lie side by side, the external at first on the inner side. The superior carotid triangle contains important arteries, veins, nerves, and organs, viz.: — Arteries.— Bifurcation of the common carotid, external and internal carotid, and five branches of the external carotid (superior thyroid, lingual, facial, ascending pharyngeal, and occipital). Veins.— The internal jugular, and those which open into it (superior thyroid, lingual, facial, pharyngeal, and sometimes the occipital). Nerves.— Three cranial (the pneumogastric and one of its branches — the superior laryngeal; the hypo-glossal, and one of its branches — the descendens noni [descending of the ninth] and the spinal ac- cessory), the sympathetic, and the external laryngeal (branch of the superior laryngeal). Organs.— One symmetrical half of the lower part of the pharynx, and the upper part of the larynx. The inferior carotid triangle also contains arteries, veins, nerves, and organs, viz.: — Arteries.— Common carotid and inferior thyroid. Veins.— Internal jugular, middle thyroid, and vertebral. Nerves.— Pneumogastric and a branch (the recurrent laryngeal), de- cendens noni, communicans noni, and sympathetic. 434 SURGICAL ANATOMY. Organs.— Trachea, thyroid gland, and lower part of the larynx. One half of these lie on either side of the neck; i. e., they lie in the median line. The submaxillary triangle contains arteries, veins, nerves, and glands, viz.: — Arteries.— External carotid, internal carotid, facial, sub-mental, and several smaller branches. Veins.— Internal jugular, commencement of the external jugular, the facial, and those which open into it below the jaw; viz., the sub- mental, submaxillary, inferior palatine, and ranine. Nerves.— Deeply situated at the back part of the space are the pneu- mogastric and glosso-pharyngeal. Glands.—Portion of the parotid and submaxillary glands and lym- phatic glands. The occipital triangle contains the transversalis colli (transverse of the neck) artery and vein, the spinal accessory and cervical nerves, and lymphatic vessels and glands. The subclavian triangle contains the third portion of the sub- clavian artery, the transversalis colli artery and vein, the brachial plexus and cervical nerves, the external jugular vein, and the sub- clavian when it ascends above the clavicle, and lymphatic vessels and glands. THE PERINEUM. The perinseum (about the scrotum) may be briefly defined as the floor of the pelvis, or, indefinitely, as the parts in the region of the out- let of the pelvis ; but more definitely, the perinseum may be described as consisting of two parts,— the superficial and deep perinseum, or per- ineal body. The superficial perinseum is the triangular space at the outlet of the pelvis, bounded by lines connecting the tuberosities of the ischia (the lowest projections of the hip bones) with each other, and with the apex of the arch of the pubes. The deep perinseum (the perineal body) is a thick and firm, but irregular, triangular pyramid, whose base is formed by the superficial perinseum, and whose vertex, in the female, extends upward to the point of approximation of the rectum and posterior wall of the vagina. The perineal body is composed of fibro-elastic tissue, nerves, and blood-vessels. In the male, this body includes the prostate gland, Cowper’s glands, the neck of the bladder, and the fixed portion of the urethra. INDEX. Abdomen, 367 openings from, 367 muscles of, 168 regions of, 368 viscera of, 367 Abdominal aorta, 211 branches of, 209, 211 muscles, 168 rings, 427 viscera, position, 369 Acetabulum, 111 Air-cells, 389 Air-tubes, 389 Alimentary canal, 358 Alveoli of the jaw, 39 of the lungs, 389 Anatomy: — definitions of, 22 surgical, 425 Ankle, 101 joint, 138 Aorta, 209 branches of, 211 Aponeurosis, 145 Aquaeductus Fallopii, 58 Aqueous humor, 344 Arachnoid membrane, 270 Arbor vitae, 281 Arch, deep palmar, 238 superficial, 238 zygomatic, 54 Arm, artery of, 233 bone of, 86 muscles, 154 nerves, 314, 317 Arteries, 209 definition of, 208 anterior tibial, 224 ascending pharyngeal, 241 aortic intercostal, 212 axillary, 232 basilar, 229 Arteries : — brachial, 233 branches of, 235 bronchial, 212 carotid, 212 central of the retina, 245, 246 cerebral, 229, 246 ciliary, 246 circle of Willis, 231 common iliac, 218 cceliac axis, 214 communicating, 246 epigastric, deep, 220 facial, 240 femoral, 221 deep, 224 frontal, 246 hemorrhoidal, 216 hypogastric, 421 iliac, common, 218 external, 220 internal, 218 inferior thyroid, 232 inferior mesenteric, 216 innominate, 212 intercostal, aortic, 212 internal carotid, 243 iliac, 218 mammary, 231 maxillary, 243 lachrymal, 246 lingual, 240 lumbar, 217 mammary, internal, 231 maxillary, internal, 243 mesenteric, superior, 215 inferior, 216 nasal, 246 occipital, 241 oesophageal, 212 ophthalmic, 245 palmar arch, deep, 238 436 INDEX. Arteries : — palmar arch, superficial, 238 palpebral, 246 pericardiac, 212 peroneal, 226 phrenic, 213 plantar, 226 popliteal,, 224 posterior auricular, 241 cerebral, 229 tibial, 226 profunda femoris, 224 radial, 237 renal, 216 sacra media, 218 sciatic, 219 spermatic, 217 subclavian, right, 227 superior epigastric, 231 superior intercostal, 232 profunda, 237 supra-orbital, 246 supra-renal, 216 supra-scapular, 232 temporal, 243 thyroid axis, 231 tibial, anterior, 224 transversalis co-lli, 232 ulnar, 238 vertebral, 229 Astragalus, 101, 102 Atlas, 72 Axillary space, 430 Axis, 72 Axis cylinder, 295 Back, muscles of, 152 Base of brain, 230 of skull, 70 Bicuspid, 362 Biliary ducts, 384 Bioplasm, 17 Bladder, 405 neck of, 406 Blood, 19 foetal circulation, 421 Bone, or bones, 23 diploe of, 33 eminences and depressions of, 34 epiphysis, 38 names of, 27 number of, 25 Bone, or bones : — of the cranium, 29 of the wrist, 93 ossification of, 31 ossific centers, 31 periosteum of, 30 structure of, 33 astragalus, 101 atlas, 72 axis, 72 calcaneum, 101, 102 clavicle, 81 coccyx, 77, 78 cuboid, 101 cuneiform of the wrist, 93, 101 of the ankle, 101 ethmoid, 50 femur, 106 fibula, 105 frontal, 59 heads of, 34 hip-bones, no humerus, 86 hyoid, 67 incus, 352 inferior maxillary, 39 turbinated, 45 innominate, no lachrymal, 47 magnum, 93 malar, 48 malleus, 352 maxillary, inferior, 39 superior, 41 metacarpal, 95 metatarsal, 98 nasal, 46 occipital, 64 palate, 49 parietal, 62 patella, 105 phalanges of foot, 97 of the hand, 97 pisiform, 93 pubes, 115 radius, 92 ribs, 78 sacrum, 76 scaphoid of wrist, 93 of ankle, 101 scapula, 82 semilunar, 93 sesamoid, 23 INDEX. 437 Bone, or bones : — sphenoid, 52 sphenoidal turbinated, 51 stapes, 352 sternum, 79 superior maxillary, 41 temporal, 54 tibia, 103 trapezium, 93 trapezoid, 93 turbinated, inferior, 45 ulna, 88 unciform, 93 vertebrae, 71 vomer, 45 Brain, ventricles of, 281, 282, 285 lobes of, 284, 285 membranes of, 269 Brachial plexus, 3x6 Breasts, 420 Bronchi, 389 Bronchial vessels, 390 Bursa mucosa, 121 CEecum, 378 Calf of the leg, 178 Canal, or Canals: — anterior palatine, 42 alimentary, 358 carotid, 57 dental, anterior, 44 inferior, 40 posterior, 42 femoral, 368, 429 Haversian, 33, 38 infraorbital, 43 inguinal, 426, 427 lachrymal, 350 spinal, 273 semicircular, 355 Capillaries, 209 Capsules, supra-renal, 408 Cardiac plexus, 330 Carpus, 93 Cartilage, costal, 78 cricoid, 395 ensiform, 79 of the larynx,393 of the nose, 342 of the pinna, 35r tarsal, 350 thryoid, 394 Cell, or cell life, 17 Cementum, or cement, 363 Center of ossification, 31 Cerebellum, 279 Cerebro-spinal axis, 268 fluid, 273 Cerebrum, 283 Cervical plexus, 316 Chorda tympani, 309 Chyle, 19 Ciliary muscle, 348 Circle of Willis, 231 Circulation of the blood, 202, 204 in the foetus, 421 Clavicle, 81 Coagulum, 20 Coats of the eyeball, 344 Coccyx, 78 Cochlea, 355 scalse, or ladders of, 356 Coeliac axis, 214 Colon, 376 Column of Goll, 277 of Burdach, 277 ofTurck, 277 Condyles of the femur, 108 of occipital bone, 65 of lower jaw, 40 of humerus, 88 Constrictors of the pharynx, 173 Convolutions of the brain, 286 Cords, vocal, 398 Corpora striata, 291 quadrigemina, 294 Corpus dentatum, 279, 281 callosum, 283 Corpuscles, 20 Corti, organ of, 356 Costal cartilages, 78 Cranial nerves, 297 office of, 301 origin of, 311 Cranium. 25 Crassamentum, 20 Crest of the ilium, 112 Cribriform fascia, 193 Crista galli, 37 Crystalline lens, 347 Cuboid bone, 101 Cuneiform, 93 Cytoblast, 18 Dartos, 411 Dentes (teeth), 360 438 INDEX, Deglutition, 176 Deltoid muscle, 182 Dermatology, 23 Diaphragm, 163 Diaphysis, 38 Diarthrosis, 123 Different names of the same muscle, 146 Digestion, organs of, 358 Diplde, 33 Drum of the ear, 352 Ducts, biliary, 384 common bile, 384 ejaculatory, 409 nasal, 44, 350 thoracic, 266 Ductus communis choledochus, 384 Duodenum, 374 Dura mater, 271 Ear, 351 labyrinth of, 354 middle, 352 Ectoblast, 18 Ejaculatory duct, 409 Elbow joint, 131 Encephalon, 268, 269 Ensiform appendix, 79 Epiglottis, 397 Epiphysis, 38 Ethmoid bone, 50 Eustachian valve, 205 tube,352 Extensor of foot, 178 Extensor of leg, 180 Eyes, 343 Eyeball, 344 Eyelids, 349 Fallopian tubes, 417 Falx cerebri, 271 Falx cerebelli, 271 Fascia lata, 192 cribiform, 193 palmar, 193 of the thigh, 192 Fauces, 359. Female genital organs, 416 Femoral hernia, 428 Femur, 106 Fibrin, 21 Fibula, 105 Filum terminale, 272 Fingers, muscles that move them, 193 flexed by, 196 Fissures, longitudinal, 283 sphenoidal, 52 of spinal cord, 275 of Rolando, 284 of Sylvius, 284 Floating ribs, 79 Fluids of the body, 19 Foetal circulation, 421 Foramen, lacerated, 57 magnum, 65 stylo-mastoid, 58 Fornix, 293 Fourth ventricle, 281 Frontal bone, 59 Gall bladder, 384 Ganglia, nerve, 296 Gasserian, 304 sympathetic, 327 Gladiolus, 79 Genital organs : — male, 409 female, 416 Glands, Cowper’s, 409 lachrymal, 305 mammary, 420 meibomian, 350 mesenteric, 387 prostate, 409 Peyer’s, 376 salivary, 364 sweat, 337 solitary, 376 Glottis, 398 Groups of muscles : — number of, 163 of the cranium and face, 148 of the neck, 150 of the trunk, 152 of the upper extremity, 154 of the lower extremity, 155 Hairs, 335 Hamstrings, 108 Heart, 202 valves of, 204, 206 Heart-strings, 206, 207 Hernia, 426 femoral, 428 INDEX. 439 Hip-bone, xio development of, 116 Hip-joint, 142 Hippocampus major, 293 minor, 293 Histology (tissue-study), 22 Humerus, 86 Hymen, 416 Hyoid bone, 67 Hypogastric arteries, 421 Ileo-csecal valve, 378 Ileum, 375 Ilium, no Iliacus muscle, 186 Iliac fossa, 114 Incus,352 Inferior maxillary bone, 39 meatus of nose, 69 turbinated bone, 45 Infundibulum of the ethmoid, 69 Inguinal glands, 267 Innominate artery, 212 Intestine, large, 376 small, 374 Ischium, 114 Island of Reil, 286 Interarticular fibro-cartilage, 123 Intercostal muscles, 166 Intertrocanteric line, 106 Intervertebral substances, 126 Jaw, lower, 39 Jejunum, 375 Joint (see Arthrology) : — groups of, 122 Joint-study, 121 Kidneys, 400 Knee-pan, 105 Knee-joint, 139 Labyrinth, 354 Lachrymal apparatus, 349 bones, 47 gland,350 Lacteals, 266 Larynx, 393 vocal cords of, 398 Lens, crystaline, 347 Leucocytes, 19 Leucocythemia, 19 Levatores costarum, 165 Ligamenta subflava, 126 Ligaments (see Arthrology), 120 capsular of the jaw, 124 hip, 142 knee,139, 140 shoulder, 131 check, 65, 125 Poupart’s, 114 yellow elastic, 121 round, of the hip, 106, 143 of the liver, 381 of radius and ulnar, 133 of the uterus, 417 Linea alba, 80 aspera, 108 ilio-pectinea, 116 splendens, 272 Line of beauty, 112 Lips, 359 Liver, 381 Lobes of the brain, 285 Lobes of the lungs, 389 Lower jaw, 39 Lungs, 389 Lumbar plexus, 322 Lymphatic duct, 266 glands, 263 vessels, 261 Magnum (os), 93 Malar bones, 48 Malleolus, internal, 103 external, 105 Malleus, 352 Male genital organs, 409 Mammae, 420 Manubrium, 79 Malpighian bodies, 403 Maxillary, inferior, 39 superior, 41 Meatus (external ear), 57, 351 internal ear, 57, 356 of the nose, 69 Mediastinum, 389 Medulla oblongata, 277 spinalis, 273 Meibomian glands, 350 Mesenteric glands, 267, 387 440 INDEX. Mesentery, 371 Mesoblast, 19 Metacarpal bones, 95 Metatarsal, 98 Mitral valve, 206 Molar teeth, 362 Mouth, 359 Muscles of organic life, 144 abdominal, 168 different names, 146 layers of, of the back : — first, 152 second, 153 third, 153 fourth, 153 fifth, 153 of the sole : — xst, 2d, 3d, and 4th, 162 number of, 145 of deglutition, 173 of expression, 177 of mastication, 176 of respiration, 163 of the cranium and face, 148 of the larynx, 177 of the lower extremity, 155 of the neck, 150 of the upper extremity, 154 of the trunk, 152 that move the thumb and fingers, 193 single muscles, 145 Nails, 335 Nares (nostrils), 68 Nasal bones, 46 cavities, 68, 343 duct, 44, 350 Neck, triangles of, 432 Nerves, study of, 268 anterior crural, 324 centers of brain, 295 corpuscles, 296 chorda tympani, 309, 58 great sciatic, 326 olfactory, 301 optic, 344 of animal life, 268 of organic life, 268 of respiration, 326 of the cranium, 297 Nerves: — pneumogastric, 303 spinal, 313 structure of, 295 sympathetic, 327 Nose, 341 Occipital bone, 64 CEsophagus, 367 Office of the cranial nerves, 301 Omentum, 369 Openings from the abdomen, 367 from the pharynx, 366 saphenous, 193 Optic commissure, 290 thalami, 294. Orbital muscles, 189 Organs of sense, 333 of Corti, 356 of digestion, 358 of voice and respiration, 388 Origin of the cranial nerves, 311 Osteology (bone study), 23 Os calcis, 101 Os innominatum, 110 Os magnum, 93 Ossicles, 28 Ossification, center of, 31 Ovaries, 419 Oviduct, 417 Ovum, 419 Palate, 49, 363 Palate bones, 49 Pancreas, 385 Papilla of the tongue, 337 Parietal bone, 62 Patella, 105 Pectoral muscles, 167 Pelvis, 117 Penis, 414 Pericardium, 204 Peritoneal cavity, 371 Peritoneum, 369 Perinasum, 434 Periosteum, 30 Peyer’s glands, 376 Phalanges, 97 Pharynx, 365 openings into, 366 Physiology, 23 INDEX. 441 Pia mater, 272 Pineal gland, 282 Platysma myoid, 180 Plexus, brachial, 316 cardiac, 330 cervical, 316 lumbar, 322 sacral, 324 solar, 332 Pisiform bone, 93 Popliteal space, 431 Poupart’s ligament, 114, 427 Pons Varolii, 279 Processes, articular, 74 auditory, 55 basilar, 65 coronoid, 40, 88 coracoid, 84 jugular, 65 mastoid, 56 olecranon, 90 palate, 49 prominent, 36 pterygoid, 52 spinous, 75, X13 styloid, 90 transverse, 75 zygomatic, 54 Protoplasm, 17 Proliferation, 18 Psoas magnus, 186 Pubes, 115 Pulmonary vessels, 390 Pupil, 345 Radius, 92 Receptaculum chyli, 266 Rectum, 379 Rectus femoris, 189 Reflex action, 296 Regions of the abdomen, 368 Respiration, muscles of, 163 organs of, 388 Restiform bodies, 279 Retina, 346 arteria centralis of, 245, 246 layers of, 346 Ribs, 78 Rings, abdominal, 427 femoral, 429 Rolando, fissure of, 284 Sacral plexus, 324 Sacrum, 76 Salivary glands, 364 Saphenous opening, 193 Scala (ladder) media, 356 tympani, 356 vestibuli, 356 Scaphoid bone, 93, ior Scapula, 82 Scarpa’s triangle, 430 Sciatic nerve, 326 Scrotum, 410 Segmentation, 18 Semen, 414 Semicircular canals, 355 Semilunar bone, 93 Seminal vesicles, 414 Sense, organs of, 333 Septum lucidum, 291 Sesamoid bones, 23 Shoulder-joint, 131 Sigmoid flexure, 379 Single muscles, 145 Sinuses of the brain, 247, 254 ethmoidal, 51 frontal, 60, 71 maxillary, 44 sphenoidal, 53 Skeleton, 23 Skin,333 Skull, 25 Soft palate, 363 Solar plexus, 332 Spermatic cord, 413 Sphenoid bone, 52 Sphincter ani, 380 Spinal canal, 273 Spinal column, 27 Spinal cord, 273 Spinal nerves, 313 Spine, or spinous process : — of the ilium, 1x3 of the pubes, 115 of the scapula, 82 of the vertebrae, 74, 75 Spleen, 386 Stapes, 352 Sternum, 79 Stomach, 372 Sublingual gland, 364 Submaxillary gland, 364 Superior maxillary bone, 41 Supra-renal capsules, 408 442 INDEX. Surgical anatomy, 425 Sutures, 35 coronal, 60 frontal, 60 lambdoid, 62 sagittal, 62 Sweat-glands, 337 Sympathetic nerves, 327 Symphysis of the jaw, 39 of the pubes, 115 Synovia, 121 Tarsus, iox Teeth, 360 Temporal bones, 54 Tendo Achillis, 102 Tentorium, 271 Testes, or testicles, 410 Thigh-bone, 106 Thorax, 388 Thoracic duct, 266 Throat, or pharynx, 365 Thymus gland, 392 Thyroid cartilage, 394 Thyroid gland, 391 Tibia, 103 Tongue, 337 Tonsils, 364 Torcula Herophili, 66 Trachea, 392 Tree of life, 281 Trapezium, 93 Trapezoid, 93 Triangles of the neck, 432 Scarpa’s, 430 Trochanters, 108 Tubercula quadrigemina, 294 Tuberosities of the humerus, 86 of the tibia, 103 Tuberosity, definition of, 36 Tubes, bronchial, 389 Tubuli, dental, 363 lactiferi, 420 seminiferi, 412 uriniferi, 403 Tunica albuginea, 412 of the ovary, 419 vaginalis, 411 Turbinated bones, 45 Tympanum, 352 Ulna, 88 Umbilical arteries, 421 Umbilical cord, 421, 423 Unciform bone, 93 Upper extremity, 8 Urachus, 406 Ureter, 403 Urethra, 407 Urinary organs, 400 Uterus, 416 Uvula of the throat, 363 Vagina, 416 Vagus, or par vagum, 303 Valve, or valves : — coronary, 205 Eustachian, 205 of the heart, 204, 205, 206 ileo-csecal, 378 mitral, 204 semilunar, 204 tricuspid, 204 of the veins, 247 Vasa vasorum, 209 Vaso-motor, 209 Vein, or veins, definition of, 2o8; axillary, 252 azygos, 250 basilic, 252 brachial, 252 of the brain, 253 bronchial, 251 cephalic, 252 cerebral, 254 choroid, 254 facial, 256 of the diploe, 256 femoral, 258 of the heart, 255 hepatic, 257 iliac, common, 258 external, 258 innominate, 250 jugular, 254 internal, 253 external, 253 lumbar, 257 median, 253 occipital, 256 of the neck, 254 phrenic, 257 portal, 247, 258 pulmonary, 247 renal, 257 INDEX. 443 Vein, or veins, definition of: — saphenous, 260 sinuses of brain, 254 spinal, 260 subclavian, 251 temporal, 256 temporo-maxillary, 256 ofThebesius, 250 vertebral, 253 Velum interpositum, 294 palati, 49 Vena cava, inferior, 256 superior, 249 (see Fig. 166) Vena portae, 258 Venae comites, 247 Ventricles of the brain, 291 of the heart, 203 of the larynx,398 Vertebra prominens, 72 Vertebrae, 71 Vertebral column, 71 Vertebrate animals, 71 Vocal cords, 398 Voice and respiration, 388 Vomer, 45 Willis, circle of, 231 Womb (uterus), 416 Wormian bones, 23 Wrist-bones, 93 Xiphoid appendix, 79 Zygomatic arch, 54 APPENDIX. COMPLETE LIST OF THE MUSCLES, INCLUDING THEIR ORIGIN, INSERTION, NERVE SUPPLY, AND USE, ALPHABETICALLY ARRANGED. 1. Abductor indicis (outward mover of the index finger), extends from the metacarpal bone of the thumb to the forefinger. It brings the forefinger toward the thumb ; i. e., away from the median line of the hand (see Fig. 128) ; seen in the figure near the thumb. All the muscles of the upper extremities are supplied by branches or nerves of the brachial plexus, which is formed by the union of the culterior branches of five spinal nerves (the four lower cervical and the first dorsal). These nerves all come from ganglia of the brain and cord. 2. Abductor minimi digiti (outward mover of the little toe, or little finger). That of the foot extends from the outer tuberosity of the heel bone (os calcis, or calcaneum) to the outer side of the base of the first bone of the little toe. It is controlled by the external plantar nerve. The plantar nerves are branches of the posterior tibial, and the latter is a continuation of the internal popliteal. The popliteal nerves are branches of the great sciatic. (Figs. 101 and 106.) The abductor minimi digiti of the hand extends from the pisiform bone of the wrist (and also from the tendon of the flexor carpi ulnaris) along the ulnar border of the palm of the hand to the base of the first bone of the little finger, moved by means of the ulnar nerve. The ulnar is derived from the brachial plexus, and is placed along the inner or ulnar side of the upper limb. (Fig. 128.) 3. Abductor pollicis, or abductor hallucis (outward mover of the great toe and thumb). That of the foot extends from the inner tuberosity of the heel bone and other attachments, along the inner border of the foot to the inner side of the base of the first bone of the great toe. It moves the toe outward from the median line of the foot, but toward the median line of the body. Internal plantar nerve. (Figs. 101 and 106.) Abduc- tor hallucis. The abductor pollicis of the hand is a thin, flat, sub- cutaneous muscle, extending from the trapezium of the wrist to the radial side of the base of the first bone of the thumb. It moves the thumb outward, and is supplied by the median nerve from the brachial plexus. (Fig. 128.) 4. Accelerator urinae. This muscle belongs only to the male, and forms one of the perineal group of the muscles of the trunk of the body. It arises from the central tendon of the perineum, and encircles the canal 2 APPENDIX. of the urethra. It serves to constrict the urethra, and thus expel its con- tents. By compressing certain blood-vessels, it is said to aid in filling erectile tissue of the male. It is referred to on page 153. Supplied by the perineal nerve, which is a branch of the pudic, and comes from the sacral plexus. 5. Accessorius ad sacro-lumbalem (aid to the sacro-lumbar). This muscle lies upon the back, in the fourth layer from the skin, and extends from the angles of the six lower ribs to the angles of the six upper ribs. It is governed by branches of the dorsal (spinal) nerves, and serves to erect the spine and bend it backward. 6. Accessorius oi'bicularis superioris (or simply ac. orbicularis oris). This muscle consists of two bands extending from the upper jaw, opposite the incisor teeth, outward on each side to the angle of the mouth. It aids the orbicular, which is a sphincter muscle, in closing the lips. Governed by the facial (seventh cranial) nerve. 7. Adductor brevis. This is a triangular muscle at the inner side of the thigh, and extends from the pubis obliquely backward, outward, and downward, to the upper part of the linea aspera (rough line) at the back of the femur. The three adductors (brevis, longus, and magnus) and the pectineus together, adduct the thigh, and make the knees approach each other. They are all governed by the obturator nerve, which is a branch of the lumbar plexus. (See Figs. 123 and 125.) 8. Adductor longus (long adductor). This muscle extends from the pubis in front to the middle third of the linea aspera. It is not so long as the adductor magnus. 9. The adductor magnus (great adductor) extends from the pubis and ischium along the whole length of the linea aspera. The femoral vessels pass through this muscle to enter the popliteal space. (Fig. 125.) 10. Adductor pollicis (adductor of the thumb). This muscle helps to form the ball of the thumb ; it is deeply seated, of triangular form, and arises, by a broad base, from the whole length of the third metacarpal bone on its palmar surface; the fibers converge as they proceed outward, and are attached to the base of the first bone of the thumb. Supplied by the ulnar nerve from the brachial plexus. (See Fig. 128.) Adductor pollicis (adductor of the great toe), or adductor hallucis. (See Figs. 105 and 106). The muscle moves the great toe outward toward the little toe, or toward the median line of the foot. It arises from the base of the sec- ond, third, and fourth metatarsal bones, and from the sheath of the peroneus longus (which lies obliquely across the sole of the foot), passes obliquely forward and inward, to be inserted into the base of the great toe (hallux or pollex). External plantar nerve from the sacral plexus. (See page 326, and Fig. 232.) 11. Anconeus (from a Greek word ayxwv, signifying the elbow). It is a small triangular muscle, situated at the back part of the forearm, near APPENDIX. 3 the elbow. It extends from the external condyle of the humerus to the upper third of the ulna on the back side. (Figs. 133 and 226.) It aids the triceps in extending the forearm. Governed by branches of the mus- culo-spiral nerve from the brachial plexus. 12. Anomalus (irregular). This is a small muscle about an inch in length, and belongs to the intermaxillary group upon the face. It lies between the nose and cheek, and beneath the levator labii superioris et alaj nasi. It assists the latter. Et alas nasi has the same meaning as alaeque nasi. Translated it means, and of the wing of the nose. (Fig- 95-) 13. Aryteno-epiglottideus inferior, called also the compressor sac- culi laryngis, belongs to the larynx, or laryngeal group in the neck. It extends from the arytenoid cartilage to the margin of the epiglottis. It compresses the sac of the larynx, and discharges its secretion upon the vocal cords, to lubricate them. This and the following are both governed by the recurrent laryngeal nerve, which is the motor nerve of the larynx. It is a branch of the pneumogastric. 14. Aryteno-epiglottideus superior. Extends from the arytenoid cartilage to the fold of mucous membrane, along the side of the upper aperture of the larynx. It constricts the upper aperture. (Fig. 280.) 15. Arytenoid. Extends from one arytenoid cartilage of the larynx to the other. (See Fig. 2S2.) It closes the back part of the glottis. It is a single muscle, and governed by the laryngeal nerves, superior and inferior. The latter is also called the recurrent laryngeal. 16. Attollens aurem (lifting up the ear). This is the largest of three small rudimentary muscles. (Rudimentary because not generally exer- cised, as in the lower animals.) They are placed beneath the skin around the external ear. (See Fig. 11S.) The attollens is thin and fan-shaped. It arises from the scullcap (aponeurosis of the occipito-frontalis muscle), and converges to be inserted into the upper part of the cranial surface of the pinna (external ear). The other two ( 17) attrahens and (18) retrahens aurem, draw the pinna respectively forward and backward. Their names indicate their office. Governed by branches of the facial, except the attollens, which receives filaments from the cervical plexus (from anterior branches of the spinal nerves in the neck.) 19. Azygos uvulas (literally, unpaired of the uvule ; but it is not a single muscle, as its name implies). This muscle occupies the substance of the uvule, and is attached above to the posterior part of the palate bone and to the soft palate, or velum palati. When it contracts, the uvula (or uvule) is shortened. Said to be governed by the facial nerve, but it is governed by a sympathetic nerve, and is probably supplied by the spheno- palatine ganglion. The facial is a nerve of motion. 20. Biceps flexor cubiti (two-headed flexor of the forearm). It oc- cupies the anterior surface of the arm, and when well developed and con- 4 APPENDIX. tracted forms a large bunch of flesh a little above the elbow. Its long head arises from the upper border of the glenoid cavity, and its short head from the coracoid process at the shoulder. It is inserted into the radius just below the elbow. Supplied by a branch (musculo-cutaneous nerve) from the brachial plexus. (See Figs. 109 and 122, and page 186; also page 178, 3d line.) This muscle sometimes gives off a tendon to the ulna. (See Fig. 129.) 21. Biceps flexor cruris or biceps femoris (two-headed flexor of the leg). Extends from the ischium (hip bone, or the lower portion of it) and linea aspera of the femur to the fibula just below the knee. (See Fig. 124 and page 189.) 22. Biventer cervicis (two-bellied of the neck). This muscle is small, and often blended with the complexus. It has a tendon between two fleshy bellies; and when distinct from the complexus arises from three or four upper dorsal vertebrae, and is inserted into the occipital bone, to retract and rotate (with other muscles) the head. Governed by branches of the cervical nerves. 23. Brachialis anticus. This muscle assists the biceps, beneath which it lies, to flex the forearm. It is attached to the lower half (nearest the elbow) of the humerus, and is inserted into the ulna just below the elbow. Supplied from the brachial plexus (mostly by the musculo-cuta- neous nerve). 24. Buccinator. This belongs to the intermaxillary group. (See page 149, 10th group, and Fig. 95, No. 14.) It extends from the outer surface of both jaws, opposite the molar teeth, to the angle of the mouth and lips, and is quadrilateral in form. It contracts and compresses the cheek, so as to keep the food between the teeth. Supplied by the facial nerve. (See also page 176.) 25. Cervicalis ascendens (ascending of the neck). This muscle is a continuation of the accessorius ad sacro-lumbalem into the neck. It is situated upon the back, and arises from the angles of four or five upper ribs, and extends upward to the 4th, 5th, and 6th cervical vertebrae. The pair acting together keep the neck erect. Branches of the cervical nerves control them. 26. Ciliary muscle. (See intra-ocular group, page 149, and also page 34S.) It is about one eighth of an inch broad, and arises at the junction of the cornea and sclerotic coat of the eyeball, to be attached to the choroid on its outer surface in front of the retina. It is governed by a sympathetic ganglion connected with the first division of the 5th cranial. 27. Coccygeus. Is attached to the spine of the ischium, and to the sacrum and coccyx. It forms a part of the floor of the pelvis, assists to close the pelvic cavity, and support the coccyx. 28. Complexus. Extends from the transverse processes of the 7th, 8th, 9th, and 10th vertebras, and articular processes of the 4th, 5th, and APPENDIX. 5 6th vertebrae to the occipital bone. Retracts and rotates the head. Lies upon the upper and back part of the neck, and passes obliquely upward and inwai'd. Is governed by the cervical nerves. (Fig. 108.) 29. Compressor nasi (or compressor naris). Is situated at the side of the nose. (See Fig. 95, No. 10.) It arises from the upper jaw at the side of the nose, and extends to meet its fellow on the bridge of the nose. By compressing the bridge of the nose it serves to increase its breadth and open the nostril. Supplied by the facial nerve (7th cranial). 30. Compressor narium minor (page 149), 7th group of the cranium. A small muscle extending from the lateral cartilage forming the wing (ala) of the nose, to the skin (integument) at the end of the nose. Dilates the nostril. All the muscles of this group are subject to the facial (7th cranial) nerve. 31. Compressor urethrae (compressor of the urethra). Also called constrictor urethrae. It surrounds the membranous portion of the urethra (Fig. 291), and compresses it. Is attached to the ramus of the pubis, and to its fellow of the opposite side. Perineal nerve from the sacral plexus. 32. Constrictor pharyngis inferior (lower constrictor of the throat). There are three of these muscles : the lower (33), middle, and (34) upper constrictors. (See Fig. 114, and bottom of page 173, where they are fully described.) 35. Coraco-brachialis. The name indicates its attachments to the coracoid process at the shoulder and to the humerus (bone of the arm). Draws the arm forward and inward. Musculo-cutaneous nerve from the brachial plexus; 2d group of the upper extremity, page 154. In Fig. 122 it is seen near the armpit (axilla). 36. Corrugator supercilii (wrinkler of the eyebrow). It contracts and wrinkles the eyebrow and skin of the forehead. Extends from the median line of the forehead between the eyebrows outward lo the orbicular muscle that surrounds the eye. See Fig. 94, 4th group of the cranium and face, page 149. Facial nerve. 37. Cremaster (suspender). It draws up the testicle. See first group (abdominal) of muscles of the trunk, page 152 and page 173. It consists of loops of muscular filaments from the internal oblique muscle. These loops form a thin covering of the spermatic cord, and some of them descend to the testicle, and are inserted into one of its coverings (the tunica vaginalis. Fig. 111.) Nerves from the lumbar plexus. 38. Crico-arytenoideus la.eralis, and 39. Crico-arytenoideus posticus. The name of these two muscles indicates their position and attachments. See Figs. 280 and 282, and page 151. The 9th (laryngeal) group of the neck. They both arise from the cricoid cartilage of the larynx, and are inserted into the base of the arytenoid cartilage of the same side. One (the lateralis which, with the arytenoid, closes the glottis) is attached to the side of the cricoid, and 6 APPENDIX. the other (the posticus which opens the glottis) to the posterior surface of the cricoid cartilage. For the structure of the larynx, see page 393. Recurrent laryngeal nerves (branches from the pneumogastric (10th cranial) control these muscles of the larynx. By careful observation we may find a harp in the larynx. Take the first four letters of the word and construe them thus, “Lyra,” and we have the Latin word for harp. Properly cultivated and used the larynx becomes a veritable harp of wonderful power. 40. Crico-thyroid. Extends from the cricoid cartilage to the thyroid, and tenses the vocal cords. Superior laryngeal nerve from the pneumo- gastric. The recurrent laryngeal nerve is also called the inferior laryn- geal. (Fig. 279.) 41. Crureus (or cruralis). It comes from a word signifying leg, or thigh. Belongs to the anterior femoral (2d) group of the lower extremity (page 155). It covers the front of the femur, and really forms a part of the vastus internus, which is itself a part of the great triceps extensor of the leg. It is attached to the kneepan (patella). Supplied by the anterior crural nerve from the lumbar plexus. 42. Deltoid. Fully described on p. 182, and shown in Figs. 108, 120, and 122. Belongs to the omo-brachial (2d) group, of the upper extremity (page 154). 43. Depressor alae nasi (depressor of the wing of the nose). Nasal (7th) group of the cranium page 149, and Fig. 95, No. 24. This mus- cle lies under the upper lip, beneath the mucous membrane that covers the upper jaw, and extends from the bone just above the front teeth (incisors) to the septum (partition) and back part of the wing of the nose. It con- stricts the nostril. 44. Depi'essor labii inferioris, or quadratus menti. This muscle lies upon the chin (mentum), Fig. 95, No. 4, and belongs to the inferior maxillary (9th) group of the cranium and face (page 149). It arises from the external oblique line of the lower jaw, and ascends somewhat obliquely upward to the integument of the lower lip and orbicular muscle of the mouth. It draws the lower lip downward and outward in the direction of its fibers. Facial nerve. 45. Depressor anguli oris (depressor of the angle of the mouth, as its name implies). Arises with the former (see Fig. 95, No. 3), but runs more directly upward to the angle of the mouth. Facial. 46. Diaphragm. (Fig. 107, page 163.) Governed by the phrenic nerves (deep branches of the cervical plexus) and by sympathetic gang- lia connected with the pneumogastric nerves. The diaphragm is the most important muscle of respiration. (See page 163, also, for muscles of respiration.) 47. Digastric (two bellied) muscle. Lies in the neck, above the hyoid bone (3d group of the neck, page 150, Figs. 119 and 113). It ex- APPENDIX. 7 tends from the inner surface of the lower jaw at the chin, through a loop attached to the hyoid bone to the mastoid process of the temporal bone, just behind the external ear (pinna). It draws up or elevates the hyoid bone and tongue. It is one of the muscles that mark the limits of the surgical triangles of the neck (page 432). Governed by the facial nerve. (See page 173.) Some authors say that the anterior belly of this muscle is supplied from a branch (mylo-hyoid) of the 5th cranial. 48. Dilator naris anterior, and (49) dilator naris posterior. These muscles are also called levator proprius alee nasi anterior and posterior. They belong to the nasal group, and are found near the end of the nose (Fig. 95, Nos. 21 and 22). They are small muscles, but help to dilate the nostril. Facial nerve. 50. Dorsal interossei. These muscles are found in both the hands and feet (palmar and inferior pedal groups, see pages 155 and 162, and Figs. 132 and 135). The interossei of the hand are supplied by the ulnar nerve, and those of the foot by the plantar from the great sciatic. The interossei abduct the fingers and toes from the median line. 51. Erector penis. This is one of the perineal (4th) group of the trunk of the body (page 153). It extends from the pubis and ischium to the crus, or root, of the penis, and serves to maintain the erect position of that organ. Supplied by the perineal nerve from the sacral plexus. In the female, the (52) erector clitoridis, a very small muscle, corre- sponds to the above. 53. Erector spinte. This muscle lies in the fourth layer of the back (page 153), and helps to maintain an erect position of the spinal column, or bend it backward. It extends from the crest of the ilium, sacrum and lumbar vertebras to a point or line opposite the twelfth (lower) rib, where it divides into the 54. Longissimus dorsi and (55) sacro-lumbalis, which are continued upward to be inserted into the vertebras and ribs above. Supplied by posterior branches of the spinal nerves. 56. Extensor brevis digitorum (short extensor of the toes). It occupies the upper part or dorsum of the foot, and forms the eleventh group of the lower extremity. It arises from the outer side of the heel bone (os calcis), and from a portion of the annular ligament of the ankle, and passes obliquely across the foot to terminate in four tendons. The innermost tendon is inserted into the first bone of the great toe ; the other three into the extensor tendons of the next three toes. This muscle aids the long extensor of the toes (57) (extensor longus digitorum), which arises from the upper part of the tibia and fibula, and occupies a position on the forepart of the leg. The latter (long extensor) terminates, after passing through the annular ligament, in four tendons that run across the dorsum of the foot to the four lesser toes. These muscles are supplied by the anterior tibial nerve from the external popliteal (or peroneal), great 8 APPENDIX. sciatic, and sacral plexus. These latter are all branches of the sacral nerves or cauda equina from the spinal cord. 58. Extensor carpi radialis brevior (short radial extensor of the wrist). Situated upon the posterior part of the forearm, and forming one of the cubital group (page 154), which includes twenty muscles. It is one of eight muscles that arise from the outer or external condyle of the humerus (page 88). It passes beneath the annular ligament of the wrist to the base of the middle (third) metacarpal bone (Fig. 133). Supplied by a branch (posterior interosseus) of the musculo-spiral from the brachial plexus. Extends the wrist. 59. Extensor carpi radialis longior (Fig. 133). Arises from the external condyle of the humerus, and extends to the second metacarpal bone. This, with the preceding and the (60) extensor carpi ulnaris, are the extensors of the wrist. They all arise from the external condyle, and are all governed by nerves from the musculo-spiral. The latter muscle is in- serted into the fifth metacarpal bone (the one that joins the little finger). 61. Extensor coccygis. Extends from the lower part of the sacrum to the lower part of the coccyx, which it extends. Sacral nerves. 62. Extensor communis digitorum (common extensor of the fingers). On the back part of the forearm (Fig. 133). Arises from the external condyle at the elbow, and just below the middle of the forearm divides into three tendons, passes, together with the tendon of the extensor indicis, through a separate compartment of the annular ligament at the wrist, across the back of the hand, to the second and third bones of the fingers. After reaching the back of the hand, the innermost (one nearest the little finger) of the three tendons divides into two, making four tendons, one for each finger. The tendons of the middle, ring, and little fingers are connected together on the back of the hand by small, oblique, tendinous slips. Supplied by the posterior interosseus nerve, a branch of the musculo-spiral, from the brachial plexus. 63. Extensor indicis (Fig. 134). Extends from the posterior surface of the ulna to the second and third bones of the forefinger. Its name indicates its office. 64. Extensor minimi digiti (extensor of the little finger). External condyle at the elbow to the second and third bones of the little finger. 65. Extensor ossis metacarpi pollicis (extensor of the metacarpal bone of the thumb. Fig. 134). From the posterior surface of the radius and ulna to the base of the metacarpal bone of the thumb. Ex- tends the thumb. 66. Extensor primi internodii pollicis. For complete list of the muscles that move the thumb and fingers, with description of the same, see pages 193-201. The last-named muscle, extensor of the first bone of the thumb, extends from the back side of the radius to the first bone of the thumb. It extends the thumb. APPENDIX. 9 67. Extensor proprius pollicis (proper extensor of the great toe). [The term pollex (genitive pollicis) is applied to both the great toe and thumb.] This muscle extends from the anterior surface of the fibula to the last bone of the great toe, through a distinct canal in the annular liga- ment at the ankle. 68. Extensor secundi internodii pollicis (extensor of the second bone, or second phalanx, of the thumb). From the back of the ulna to the last bone of the thumb. Extends the thumb. Posterior interosseus nerve (Fig. 134)- 69. Flexor accessorius (assistant flexor. Fig. 104.) This muscle belongs to the twelfth and last group (inferior pedal) of the lower extremity. It is situated in the second layer from the integument,—the flexor brevis digitorum (Fig. 101) being subcutaneous, or nearest the plantar surface of the foot. The assistant flexor arises from both sides of the heel bone, and passes forward to join the tendon of the flexor longus digitorum, which it draws to the middle line of the foot as it crosses the sole. It assists the latter. External plantar nerve. 70. Flexor brevis digitorum (short flexor of the toes. Fig. 101). Lies in the middle of the sole, beneath the integument and plantar fascia. It extends from the heel bone forward ; and beneath the instep divides into four tendons, one for each of the lesser toes. Opposite the middle of the first phalanx each tendon is divided, to allow the passage of the corresponding tendon of the long flexor, then reunites, and is again divided, to be inserted into the sides of the second phalanx of the toes. The names of these muscles indicate their use. Governed by the internal plantar nerve. 71. Flexor minimi digiti (flexor of the hand or little toe). That of the foot lies on the sole, beneath the metatarsal bone of the little toe. It is sometimes called the flexor brevis minimi digiti (see Fig. 105). It arises from the base of the metatarsal bone of the little toe, and from the sheath of the peroneus longus, and is inserted into the base of the first bone of the little toe. External plantar nerve. The flexor minimi digiti of the hand (Fig. 128) arises from the unciform bone and annular liga- ment of the wrist, and is inserted into the base of the first bone of the little finger. Supplied by the ulnar nerve. 72. Flexor brevis pollicis (short flexor of the thumb or great toe). [Figs. 128 and 131 for that of the thumb, and 105 and 106 (here called flexor brevis hallucis) for that of the foot.] That of the thumb arises from three bones of the wrist (trapezium, trapezoid, and os magnum), the annular ligament, third metacarpal bone, and sheath of the flexor carpi radialis, and extends to both sides of the first bone of the thumb. Ulnar nerve. The short flexor of the great toe arises from two bones (cuboid and external cuneiform) of the ankle, and extends to both sides of the first bone of the great toe. A sesamoid bone is usually developed in each 10 APPENDIX. of the two tendons at or near its insertion at the ball of the great toe. Internal plantar nerve. 73. Flexor carpi radialis (radial flexor of the wrist. Fig. 129, No. 5). From the internal condyle at the elbow to the base of the meta- carpal bone that connects with the forefinger (the second metacarpal). The radial artery, near the wrist, lies just outside of the tendon of this muscle when the palm is turned upward. Flexes the wrist. Median nerve. 74. Flexor carpi ulnaris (ulnar flexor of the wrist. Figs. 134 and 129, No. 7). Lies along the ulnar side of the forearm. Extends from the internal condyle and olecranon process at the elbow to the pisiform and fifth metacarpal bones, and to the annular ligament at the wrist. Ulnar nerve. 75. Flexor profundus digitorum (deep flexor of the fingers). (Figs. 131 and 134.) Lies on the ulnar side of the forearm, beneath the super- ficial flexors, and arises from the upper two thirds of the ulna, divides into four tendons, and is inserted into the last bones (third phalanx) of the fingers near their ends. Opposite the first phalanx the tendons pass between the slips of the tendons of the flexor sublimis. Ulnar and median (through the anterior interosseous) nerves. Flexes the last, or third phalanx. The second phalanx is flexed by the 76. Flexor sublimis digitorum muscle, which we will now describe. (Fig. 129, No. 8.) Arises from the internal condyle, coronoid process of the ulna, and from the oblique line of the radius. It forms a broad and thick muscle, which divides near the middle of the forearm into four tendons; these pass beneath the annular ligament at the wrist, to cross the palm, and be inserted into the sides of the second phalanx near their center. A synovial sheath invests the tendons as they pass beneath the annular ligament. Supplied by the median nerve. 77. Flexor longus digitorum (long flexor of the phalanges of the toes). Situated on the tibial or inner side of the leg. (Fig. 104 shows the tendons on the sole of the foot.) The muscle arises from the shaft of the tibia (posterior surface), passes behind the inner malleolus at the ankle, obliquely forward, beneath the arch of the os calcis (heel bone) into the sole, where it is joined by the accessorius, which holds it in the middle line of the foot, and dividing into four tendons is inserted into the bases of the last phalanx of the toes. It flexes the phalanges, and, when the action is continued, extends the foot upon the leg, thus assisting the gastrocnemius and soleus in rising on tiptoe. 78. Flexor longus pollicis (long flexor of the thumb and great toe). That of the foot (tendon shown in Fig. 104) extends from the lower two thirds of the fibula to the last bone of the great toe. Posterior tibial nerve. The long flexor of the thumb (Fig. 129) extends from the shaft of the radius to the last bone of the thumb. Anterior interosseous nerve. APPENDIX. 11 79- Gastrocnemius (“belly,” or “ calf” of the leg). This is described on page 178, and shown in Fig. 117. In Fig. 99 it is partly removed, to show the soleus which lies beneath. Internal popliteal nerve. 80. Gemellus inferior, and 81. Gemellus superior (twins). These muscles extend from the ischium to the great trochanter at the upper part of the thigh, and rotate the thigh outward. Sacral nerves. 82. Genio-hyo-glossus. (See page 339, and Figs. 240 and 241.) Hypoglossal nerves. 83. Genio-hyoid. (Fig. 241.) Extends from the chin to the hyoid bone, which it draws forward. Hypoglossal nerve. 84. Gluteus maximus. (Fig. 108.) 85. Gluteus medius, and 86. Gluteus minimus. These all extend from the ilium (upper part of the hip bone) to the great trochanter, near the upper extremity of the femur (thigh bone), and rotate and abduct the thigh. The gluteus maxi- mus rotates the thigh outward ; the gluteus minimus rotates it inward ; and the gluteus medius helps one or the other by the separate action of its anterior and posterior fibers—the posterior assisting the larger muscle, and the anterior the smaller. When the thigh is fixed these muscles support the pelvis and trunk upon the head of the femur; and in stooping draw the pelvis back to gain the erect posture, being assisted by the ham-string muscles on the back of the thigh. The nerves come from the sacral plexus. 87. Gracilis (slender, graceful). (Fig. 99.) Arises from the ramus of the pubis and ischium, and extends the whole length of the thigh to the tibia below the knee. At the knee it passes behind the internal condyle of the femur, and curves round the inner tuberosity of the tibia. It belongs to the internal femoral region, and assists the three adductors (magnus, longus, and brevis) and pectineus to draw the thigh inward. It assists the sartorius in flexing the leg upon the thigh, and if the lower ex- tremities are fixed, serves to maintain the body in the erect posture, or flex the pelvis upon the thigh. Obturator nerve (branch of the lumbar plexus). 88. Hyo-glossus (hyoid bone and tongue). (See page 340 and Fig. 241.) 89. Iliacus. (Page 186 and Fig. 123.) It extends from the inside surface of the ilium above the pelvis to the small trochanter in conjunction with the psoas magnus. Rotates the thigh outward, bends it upon the pelvis, and the pelvis upon the thigh. It emerges from the abdominal cavity beneath Poupart’s ligament in the groin. Anterior crural nerve. 90. Infracostal (within the ribs). These are not constant. Are most frequent between the lower ribs. 91. Infraspinatus (“below the spine” of the scapula, or shoulder blade). (Fig. 121.) From the back of the scapula (the infra-spinous 12 APPENDIX. fossa) to the great tuberosity of the humerus at the shoulder. Rotates the humerus outward. Supra-scapular nerve from the cervical nerves. This nerve is shown at the upper part of Fig. 226. (See also the supraspinatus and infraspinatus muscles, page 184.) 92. Intercostals (between the ribs). (Pages 166, 171. See also Fig. hi.) The external raise the ribs, while the internal intercostals depress the ribs. 93. Interspinales (between the spines, or spinous processes of the vertebrae). These consist of small muscular fibers, or bundles of fibers, connecting the spinous processes of contiguous vertebrae. There are usually 14 or 15 pairs of them ; but they are not constant. When present they aid in bringing the body to an erect posture, or flexing it backward. Spinal nerves. 94. Intertransversales (between the transverse processes of the verte- brae). These serve to balance the body, or bend it to one side. Spinal nerves. 95. Latissimus dorsi (broadest of the back). (For description, see page 182, and Figs. 108, 120, and 121.) 96. Laxator tympani. Belongs to the tympanic, or middle ear group (pages 149 and 353). Said to be supplied by a branch from the facial (7th cranial). •97. Levator anguli oris (lifter of the angle of the mouth). (Fig. 95, No. 13.) Superior maxillary group (page 149). Runs from the upper jaw directly downward to the angle of the mouth, which it elevates. Facial nerve. 98. Levator anguli scapulas (lifter of the angle of the shoulder blade). Runs from the upper cervical vertebras to the upper angle of the scapula, which it elevates. Cervical nerves. 99. Levator ani. Perineal group of the trunk (page 153). A broad, thin muscle on each side of the pelvis. Is attached to the pubis, ischium, and coccyx, and unites with its fellow of the opposite side in the floor of the pelvis. It supports the viscera, and surrounds the structures that pass through the pelvic outlet. Sacral nerves. 100. Levatores costarum (lifters of the ribs). Thoracic group of the trunk (page 152. See, also, page 165). 101. Levator labii inferioris, or levator menti. Inferior maxillary group (page 149 and Fig. 94). From the inferior maxillary bone down- ward to the skin of the chin. Facial nerve. 102. Levator labii superioris. Superior maxillary group (page 149, Fig. 95, No. 12). Lower margin of the orbit to the upper lip, which it elevates. 103. Levator labii superioris alaeque nasi (lifter of the upper lip and wing of the nose). Et alas nasi is the same as alasque nasi. (See Fig. 95, No. 11.) Extends from the nasal process of the upper jaw near the 13 APPENDIX. angle of the eye, to the upper lip and cartilage near the end of the nose. Facial nerve. 104. Levator palati. Palatic group (page 150). A long, thick muscle just outside the posterior nostril (naris). It arises from the under sui'face of the petrous part of the temporal bone, descends obliquely downward and inward, and expands upon the posterior surface of the soft palate (velum palati) till it meets its fellow of the opposite side. It raises the soft palate. Is controlled by a ganglion, situated between the palate and sphenoid bones. 105. Levator palpebrae superioris. (See orbital muscles, page 189, and Fig. 126.) Extends from the sphenoid bone to the tarsal cartilage of the upper lid. Third cranial nerve. 106. Linqualis (tongue muscle). Supra-hyoid group of the neck (page 150, Fig. 241. For a description, see page 341). 107. Longus colli (long of the neck). Situated on the anterior surface of the spinal column, at the upper paid of the neck. It will flex and slightly rotate the neck. Cervical nerves. 108. Lumbricales (named from their resemblance to earthworms). There are four in each hand and foot. (See palmar group, page 155 and Fig.' 104.) In the hand they aid the deep flexor (flexor profundus digitorum), and in the foot the long flexor. Median and ulnar, and plantar nerves. 109. Masseter. Temporo-maxillary group. (Page 149.) (Page 176 and Fig. 264.) Inferior maxillai'y nerve—a branch of the 5th cranial. no. Multifidus spinas (manifold of the spine). The muscles fillup the groove on each side of the spine upon the back, and in various ways extend altogether from the sacrum to the axis (2d cervical vertebra). They assist in preserving the erect position of the spine, and serve to rotate it. Spinal nerves. in. Mylo-byoid. (Page 173.) 112. Naso-labialis. Superior maxillary group (page 149). This muscle is accessory to the orbicular of the mouth. Raises the upper lip. X13. Obliquus abdominis externus (external oblique of the abdo- men). (Page 169, and Figs. 108 and no.) Spinal nerves. 114. Obliquus abdominis internus. (Page 171 and Fig. in.) 115. Obliquus capitis inferior (lower oblique of the head). From the spinous process of the axis almost horizontally outward to the trans- verse process of the atlas. Rotates the atlas, and with it the head round the odontoid process, and turns the face to the same side. Cervical nerves. 116. Obliquus capitis superior. From the transverse process of the atlas to the occipital bone. It passes obliquely upward and inward, and turns the face to the opposite side. When both muscles act together, they draw the head backward. Cervical nerves. 117. Obliquus superior, and 14 APPENDIX. 11S. Obliquus inferior of the eyeball (see page 191 and Fig. 126). The inferior oblique arises from the orbital plate of the upper jaw, passes outward and backward beneath the inferior rectus muscle, to the outer part of the sclerotic coat of the eyeball. It rotates the under side of the eyeball toward the nose, and is supplied by the third cranial nerve—the motor oculi. The superior oblique rotates the upper side of the eyeball inward. 119. Obturator externus, and 120. Obturator internus, arise respectively from the outer and inner all of the pelvis and obturator membrane, and are inserted into the great trochanter of the femur. Rotate the thigh outward. The obturator in- ternus leaves the pelvis by the small sacro-sciatic notch. A synovial bursa (sac for synovial fluid) is usually found between the tendon of this muscle and the capsular ligament of the hip. I2r. Occipitofrontalis (page 180, Fig. 118). 122. Omo-hyoid. (Fig. 113 and 119.) From the upper border of the shoulder blade to the hyoid bone, which it depresses. Consists of two bellies, united by a central tendon, which passes through a sheath of cervi- cal fascia adherent to the first costal cartilage. By this means the direction of its action is somewhat changed. From the scapula it passes across the side of the neck toward the front, then ascends to the hyoid bone. 123. Opponens minimi digiti (opponent of the little finger). (Fig. 131.) From the unciform bone of the wrist on the palmar side, to the ulnar border of the fifth metacarpal bone. Causes the fifth to approach the first (that of the thumb) metacarpal bone. The word “opponens” is used in place of “flexor ossis metacarpi” of some authors. To use the latter makes this muscle read “flexor ossis metacarpi minimi digiti.” Ulnar nerve. 124. Opponens pollicis, or flexor ossis metacarpi pollicis. This muscle acts with the preceding. It causes the ball of the thumb to ap- proach the ulnar side of the palm. (Fig. 128.) From the palmar surface of the trapezium to the radial side of the first metacarpal bone. Median nerve. 125. Orbicularis oris. (Figs. 94 and 95.) Intermaxillary group (page 149). This is one of the sphincter muscles. It closes the mouth as the circular fibers of the iris close the pupil of the eye, and the orbicularis palpebrarum closes the eye itself. It consists largely of concentric fibers, which surround the orifice of the mouth and help to make up the lips. Governed by the facial nerve that comes out upon the face at the stylo- mastoid foramen, beneath the external ear passage. 126. Orbicularis palpebrarum (round of the eyelids). (Figs. 94 and 95.) Attached to the inner and outer margin of the orbit. Facial nerve. 127. Palato-glossus, and 128. Palato-pharyngeus. (These are well described on pages 175 and 176.) APPENDIX. 15 129. Palmaris interossei. (See Fig. 132, and the upper part of page 201.) They adduct toward the middle finger. 130. Palmaris brevis. Lies across the palm of the hand near the wrist, and extends from the annular ligament near the median line, to the skin on the ulnar side of the palm. It corrugates the latter. Ulnar nerve. 131. Palmaris longus (Fig. 129, No. 6). From the internal condyle at the elbow to the annular ligament at the wrist and fascia of the palm. It tenses the fascia. Median nerve. 132. Pectineus (pubic) (Fig. 123). From the ilio-pectineal line (at the brim of the pelvis) to the femur, just below the small trochanter. It flexes the thigh, and assists in walking. Anterior crural. 133. Pectoralis major, and 134. Pectoralis minor, Figs. 109 and 122. For description, see page 167, near the bottom. The pectoralis major draws the arm downward or the body upward, as in climbing. 135. Peroneus brevis. Peroneal (fibular) gi*oup, page 161. 136. Peroneus longus. The sheath and tendon of this muscle may be seen in Fig. 105. It arises from the head and shaft of the fibula, passes down behind the outer malleolus (formed by the lower end of the fibula) in a fibrous canal, is reflected obliquely across the outer side of the heel bone and beneath the cuboid, crosses obliquely the sole of the foot, and is inserted into the outer side of the base of the first metatarsal bone (con- nected with the great toe). Extends and everts the foot. Governed by a branch of the external popliteal nerve. 137. Peroneus tertius. This muscle is sometimes wanting, and when present might be described as the fifth tendon of the extensor lon- gus digitorum. It extends from the lower fourth of the fibula, beneath the annular ligament, across the dorsal surface of the instep, to the base of the fifth metatarsal bone. It flexes the ankle. Anterior tibial nerve. 138. Plantaris. Lies in the calf of the leg when present. It is some- times wanting. It arises in the popliteal space (Fig. 117) from the back side of the femur, near the outer condyle, forms a spindle-shaped belly about two inches (five centimeters) in length, and terminates in a long, slender tendon, that crosses the calf of the leg between the gastrocnemius and soleus muscles to the inner boi'der of the tendon of Achilles (heel cord), with which it becomes united to the heel bone. It is a trace, or rudiment, as some say, of a large muscle which exists in some of the lower animals. It aids the muscles of the calf of the leg in extending the foot and raising the person upon the toes. Internal popliteal nerve. 139. Plantaris interossei. These belong to the inferior pedal group, page 162. They are not in pairs, like most of the muscles, but single, and are three in number in each foot. They lie beneath, and on the inner side of, the third, fourth, and fifth metatarsal bones, and extend from the 16 APPENDIX. base and shaft of the same to the inner sides of the first phalanx. They draw the toes inward toward the great toe ; i. e., adduct toward the great toe. External plantar nerves. 140. Platysma myoid, page 180, Figs. 94 and 95. 141. Popliteus, Fig. 100, page 158. Occupies a part of the floor of the popliteal space. It arises from the outer side of the external condyle at the knee, passes obliquely downward across the lower part of the pop- liteal space, and is inserted into the posterior surface of the tibia. Assists in flexing the leg upon the thigh, and when the leg is flexed can rotate the tibia inward. Internal popliteal nerve. 142. Pronator quadratus. Cubital group, page 154, Fig. 131. Isa small, flat, square muscle, that extends across the front of the forearm, just above the wrist, from the radius to the ulna. It rotates the radius upon the ulna, turning the hand, as when we look upon the back of the hand. Renders the hand prone. Median nerve. 143. Pronator radii teres, Fig. 129, No. 4. From the inner condyle and coronoid process of the ulna at the elbow, obliquely across the fore- arm in front, to the outer border of the radius at its middle part. It ren- ders the hand prone, rotating the radius over the ulna. Median nerve from the brachial plexus. 144. Psoas magnus. (Page 186 and Fig. 123.) 145. Psoas parvus. Rarely present. When found is a long, slender muscle, extending from the sides of the lumbar vertebra; to the iliac fascia, which it tenses. 146. Pterygoid externus, and 147. Pterygoid internus. (See Fig. 116, and pages 176 and 177.) 148. Pyramidalis abdominis. (Page 172, Fig. 112.) Extends from the pubis to the linea alba. Tenses the latter. 149. Pyramidalis nasi. (Fig. 95, No. 9.) From the compressor naris muscle to the occipito-frontalis. Depresses the eyebrow. Facial. 150. Pyriformis. From the front of the sacrum within the pelvis, through the great sciatic foramen to the great trochanter. Rotates the thigh outward. Sacral nerves. 151. Quadratus femoris. From the tuberosity (lower part) of the ischium to the great trochanter. Rotates the thigh outward. 152. Quadratus lumborum. (Page 171 and Fig. 123.) The quadriceps extensor is only another name for the triceps ex- tensor femoris, which is made up of the two vasti, rectus femoris, and crureus of the thigh. 153. Rectus abdominis. (See Fig. 112, and page 168.) 154. Rectus capitis anticus major, and 155. Rectus capitis anticus minor ; both extend from the transverse processes of the cervical vertebrae upward to the under surface of the basilar process of the occipital bone in front of the spinal cord. They flex the head upon the chest. Cervical plexus of nerves. APPENDIX. 17 156. Rectus capitis posticus major. From the spine of the axis to the inferior curved line of the occipital bone. Rotates the head to one side. 157. Rectus capitis posticus minor. From the posterior part of the atlas to the occipital bone. Draws the head backward. The words anticus and posticus in the names of the four preceding muscles, refer to the position before the vertebrae and behind the vertebrae. 15S. Rectus femoris. (Fig. 123.) Forms a part of the triceps ex- tensor femoris. Extends from the lower spine (anterior inferior) of the ilium to the kneepan, and through the ligamentum patellae to the tibia. It extends the leg together with the vasti and crureus. Anterior crural nerve. 159. Rectus externus, 160. Rectus internus, 161. Rectus inferior, and 162. Rectus superior. (See Figs. 126 and 251.) These muscles move the eyeball in the direction indicated by the name. They all arise from the sphenoid bone in the back part of the orbit, and are inserted into the sclerotic coat of the eyeball. They are governed by the third cranial nerve, except the external rectus, which is governed by the sixth. 163. Rectus capitis lateralis, or simply rectus lateralis. Extends from the transverse process of the atlas to the jugular process of the occip- ital bone. Draws the head to one side. Retrehens aurem. (Fig. 118.) Described with the attolleus aurem. Has been already numbered. (See No. 18.) 164. Rhomboideus major, and 165. Rhomboideus minor. These are sometimes described as one muscle, rhomboideus. (Figs. 108 and 120.) They extend from the spine of the vertebrae, obliquely downward and outward, to the root of the spine of the scapula. Elevate and retract the scapula. 166. Risorius. (Figs. 94 and 95.) Extends from the angle of the mouth outward to the fascia covering the masseter muscle. It draws out the angle, and the two acting together widen the mouth. Facial nerve. 167. Rotatores spinae. In the dorsal region of the spine; 11 pairs. The first pair is between the first and second dorsal vertebrae, and the last between the eleventh and twelfth. From the transverse process of one vertebra, to the lamina of the next above. They rotate the vertebi'ae. Dorsal branches of spinal nerves. Sacro-lumbalis muscle. (See No. 55 of this list.) 168. Sartorius. (Figs. 99 and 123. For description, see page 186.) 169. Scalenus anticus, 170. Scalenus medius, and 171. Scalenus posticus. Prevertebral (before the vertebrae or spine) group of the neck. (Pages 150 and 165.) 18 APPENDIX. 172. Semi-membranosus. (Fig. 99.) From the ischium to the inner tuberosity of the tibia. Flexes the leg and rotates inward. Great sciatic. 173. Semi-spinalis colli. From the transverse processes of the upper four dorsal vertebrae to the spinous processes of four cervical. Erects the spinal column. 174. Semi-spinalis dorsi. Very like the former, but situated lower down on the back. Extends from the lower dorsal as high as the second cervical vertebra. Erects the spinal column. 175. Semi-tendinosus. (Fig. 99.) From the tuberosity of the ischium to the upper and inner surface of the tibia. A hamstring mus- cle. (See page 178, 9th line.) Great sciatic nerve. 176. Serratus magnus. (Fig. 109, page 167.) From 8 upper ribs obliquely round the side of the body, beneath the shoulder blade to its posterior border. Raises the ribs. 177* Serratus posticus inferior, and 178. Serratus posticus superior. These are described among tbe muscles of respiration on page 167. 179. Soleus. (Fig. 117, and bottom of page 178.) Internal popliteal nerve. 180. Sphincter ani. Perineal group, page 153. Consists of two planes of muscular fiber that surround and close the anus. Is attached to the coccyx and to the tendinous center of the perineum. Hemorrhoidal nerve from the sacral plexus. The internal sphincter ani forms a part of the rectum. 181. Sphincter vaginas. Surrounds the orifice of the vagina. Is attached to the central tendon of the perineum, and to the clitoris. 182. Spinalis colli, or spinalis cervicis. In the fourth layer of the back, page 153. From the spines of the 5th and 6th cervical to the spines of the 2d, 3d, and 4th cervical vertebrae. Steadies the neck. 183. Spinalis dorsi. Connects the spines, or spinous processes, of the dorsal and two of the lumbar vertebra. Erects the spinal column. 184. Splenius, or splenius capitis et colli. (Figs. 108 and 120.) Is situated on the back, at the base of the neck. Extends from the spines of the upper dorsal vertebra upward and outward, and divides into the splenius capitis that is attached to the occipital bone of the head, and the splenius colli that is inserted into the transverse processes of the upper cervical vertebra. One part retracts the head,‘or acting singly turns the head upward and to one side ; the other keeps the neck erect. 1S5. Stapedius. (See page 353, 3d and 8th lines.) Is attached to the neck of the stapes. Facial nerve. 186. Sterno-cleido-mastoid. (Figs. 113 and 119, and page 181.) 187. Sterno-hyoid. From the sternum and clavicle to the hyoid bone. Depresses the hyoid. Branches of the cervical nerves. APPENDIX. 19 188. Sterno-thyroid. Sternum to the thyroid cartilage of the larynx. Depresses the larynx. Hypoglossal (12th cranial). 189. Stylo-glossus. Styloid process of the temporal bone to the side of the tongue. (Fig. 241, page 341.) 190. Stylo-hyoid. Styloid process to the hyoid bone. Draws the hyoid up and back. (Fig. 173.) 191. Stvlo-pharyngeus. (Page 175.) 192. Subanconeus. From the humerus near the olecranon process of the ulna, to the posterior ligament of the elbow. Tenses the ligament. Musculo-spiral nerve. 193. Subclavius. First costal cartilage to the under surface of the clavicle. Draws the clavicle downward, or raises the costal cartilage in inspiration. 194. Subcrureus. Anterior femoral group, page 155. Draws the synovial sac upward. Anterior crural. 195. Subscapularis. Omo-brachial group, pages 154 and 186. Ro- tates the arm inward, and when the arm is raised, draws the arm down- ward or the body up. 196. Supinator brevis, Fig. 134. From the external condyle and ulna near the elbow to the neck of the radius. Supinates the hand. 197. Supinator longus, Fig. 133. Extends from the outer border of the humerus just below its middle part, or below the musculo-spiral groove, and passing over the forearm, is inserted into the styloid process of the radius at the wrist. Supinates the hand. Musculo-spiral nerve. 198. Supra-spinales. Situated in the fifth or deepest layer of the back in the neck. Six pairs. Connect the spinous processes, and bend the body backward. 199. Supra spinatus (page 184). 200. Temporal (Fig. 115, page 176). Inferior maxillary nerve. 201. Tensor palati. From the sphenoid bone, at first vertically to the hamular process of the sphenoid, which it winds around, and passes horizontally inward to expand on the anterior surface of the soft palate, which it renders tense. Otic ganglion. 202. Tensor tarsi. From the lachrymal bone to the tarsal cartilages. Palpebral group, page 149. Is situated at the inner side of the orbit, passes across the lachrymal sac, divides into two slips which cover the lachrymal canals, and is inserted into the cartilages of the lids near the tear ducts (puncta lachrymalia). It draws the eyelids inward, and compresses the lachrymal canals against the eyeball, thus placing them in the most favorable situation for receiving the tears. It also compresses the lach- rymal sac. Facial nerves. 203. Tensor tympani. Tympanic group, page 149. Is contained in a canal adjoining that for the Eustachian tube. It arises from the petrous portion of the temporal bone, passes backward to the tympanum, or middle 20 APPENDIX. ear, is reflected over the process of bone which separates the two canals, and is inserted into the handle of the malleus, to render tense the head of the drum (the membrana tympani). Otic ganglion. 204. Tensor vaginae femoris. Anterior femoral region, page 155. From the crest of the ilium (part of the hip bone) to the fascia of the thigh (see fascia lata, page 192). It tenses the fascia of the thigh. Su- perior gluteal nerve. 205. Teres major (page 185, Figs. 108, 120, 121). 206. Teres minor (page 184, Fig. 121). 207. Thyro-arytenoid. Laryngeal group, page 151. See muscles oi the larynx, pages 177 and 399. 208. Thyro-epiglotic, or thyro-epiglottideus. The names of these muscles indicate their attachments. 209. Thyro-hyoid. Infra-hyoid group, page 150. Thyroid cartilage to the hyoid bone. Elevates the larynx. Hypoglossal nerve. 210. Tibialis anticus (Fig. 103). Anterior crural group, page 160. From the outer tuberosity of the tibia to the ankle and first metatarsal bone. Flexes the ankle. 211. Tibialis posticus. Deep posterior crural group (page 160, Fig. 105). From the shaft of the tibia and fibula, to the scaphoid and internal cuneiform at the ankle. Extends the foot. 212. Trachelo-mastoid (throat and mastoid process). Post-vertebral group (page 150). Steadies the head. Branches of the cervical nerves. 213. Transversalis abdominis. (Fig. 112, and page 171.) 214. Transversalis colli (transverse of the neck). In the fourth layer of the back (page 153). From the transverse processes of five lower cervical to the third, fourth, fifth, and sixth dorsal vertebrae. Keeps the neck erect. Cervical branches. 215. Transverse of the foot (transversus pedis; Fig. 105). From the head of the fifth metatarsal bone, transversely across the sole of the foot to the base of the great toe, which it adducts in conjunction with the adductor pollicis, whose tendon blends with it. 216. Transverse of the perineum (transversus perenei). A narrow muscle that lies across the back part of the perineal space. From the fore part of the tuberosity of the ischium to the central tendon of the perineum. It supports the perineum. 217. Trapezius. (Figs. 108, 119, and 120, page 182.) 218. Triangularis sterni (page 171). Assists expiration. Intercostal nerve (anterior branch of a dorsal nerve). 219. Triceps extensor cubiti. Brachial group (page 154. See page 186). Triceps extensor femoris (anterior femoral group) is the same as the quadriceps extensor femoris. This muscle, or name, includes all of the extensor muscles of the leg. The rectus femoris and crureus, which help to make up the triceps (or quadriceps) of the femoral region, have APPENDIX. 21 been already described. The other two, included in either of the above names, are the 220. Vastus externus, and 221. Vastus internus. They extend from the posterior surface (rough line) of the shaft of the femur to the kneepan ; and the latter, which is a true sesamoid bone, is connected by the ligamentum patellae to the anterior surface of the tibia, about two inches (five centimeters) below the kneejoint. Extends the leg. Anterior crural nerve. 222. Zygomaticus major, and 223. Zygomaticus minor, belong to the superior maxillary group (page 149). They extend from the malar bone at the cheek to the angle of the mouth, and draw it upward and outward toward the cheek, as in laughing. Governed by the facial nerve. From seven to ten additional names, besides those numbered, must be learned, because the same muscle, in some instances (see page 146), has different names. The foregoing list, with its references, will greatly illuminate the study of the muscles. 22 APPENDIX. Boston, Jan. iS, 1892. Dr. C. W. Emerson, President of the Emerson College of Oratory: Dear Sir,—By your request we hereby transmit to you some of the peculiar or distinctive features of “Dutton’s Anatomy,” as compared with Gray, Quain, and in general with other authors. And first, let us mention perspicuity, which we deem most important in any work. In this respect we submit the book to your examination, well knowing that you are a most competent judge. The phraseology is new, and in this sense the book is original. Scarcely a dozen sentences of it can be found in other works. Second, the many hundreds, if not thousands, of explanations of technical terms by aid of parentheses, form a strong feature of this work. It was this idea, perhaps, more than any other, that induced the author to write on this subject. Other works were found too technical for the best promotion of science. Third, this work brings the study of anatomy into smaller com- pass. Life is not long enough to enable the student to learn the structure of the human body in detail, as it may appear on successive weeks or months during the twenty years or more of its growth under normal and abnormal conditions. This work, therefore, presents the normal structure of the body as it is at maturity, in the adult form, together with all facts of development that seem important. The student is not required to learn the art of constructing artificially human organisms, but only the art of using and preserving them. For this reason, and with the hope of ex- tending more widely the study of the most complex, the most delicate, and the most useful of all instruments and mechanisms, whether natural or artificial, we have made anatomy ?nore accessible by omitting much comparatively useless detail. Fourth, the conciseness of definitions given greatly aids the memory. Fifth, several new and important illustrations. (See diagrams of the circulation opposite pages 202 and 390) ; of the nervous system (Fig. 182) ; of the cranial and spinal nerves (Figs. 211, 212, 222, and 223) ; of the facial (Fig. 219) ; of the ureters (Fig. 286) ; the olfactory nerve and bulb (Fig. 201) ; the convolutions and fissures of the cerebrum (Fig. 199) ; a typical rib (Fig. 47) ; the chorda tympani nerve (Fig. 218) ; the brachial plexus (Fig. 224) ; circulation in the hand (Fig. 158) ; the external carotid artery and its branches (Fig. 159) ; reflex action, or the direction of the sensory and motor impulses (Fig. 210) ; branches of the subclavian artery (Fig. 150) ; the sympathetic system of nerves (Fig. ; and several others. (Possibly some of these have been introduced in later editions of Gray.) APPENDIX. 23 Sixth, a better classification and grouping of parts. See branches of the aorta (page 211) ; muscles that move the thumb and fingers (pages 193 to 201) ; the complete list of the bones, with only fifty names (page 27) ; vessels having seven branches (page 222), etc. Seventh, improvements in the science itself:— (a) The colon as a secreting and excretory organ, and distinct from the alijnentary canal. This idea was first suggested to the author by reading the works of Dr. Andrew Jackson Davis (see pages 358 and 376)- (b) The chorda tympani nerve as a part of the sympathetic system, and not a branch of the facial, which is a motor nerve (see page 309, and Fig. 218). (c) One peritoneal cavity instead of two (see page near the bottom, and Fig. 267). (d) A clearer distinction is ?nade between the fauces and pharynx (pages 176 and 359) ; between the coronoid and coracoid processes (page 176) ; between the terms artery and vein (pages 208 and 247) ; between lymph and chyle (page 19) ; between the lacerated foramina (middle of page 57) ; concerning the phalanges (page 97) ; the correct plural form of names of bones, etc. (page 25). (e) The coagulation of the blood is considered as a normal process, necessary to the up-building of the tissues. (See page 21.) (f) Only jo pairs of spinal nerves, instead of 31, as usually given. (Page 313.) (g) The origin of the word carotid. (See last third of page 238.) Eighth, the introduction of so much of physiology, or uses of the parts and organs, as is necessary to enliven the whole, and make it more attractive. Ninth, measures are given in both the common and metric systems, as a stepping-stone to the latter. Tenth, so?ne suggestions for further improvement. To substitute cer- vical for jugular, as more appropriate for the veins of the neck (page 255) ; a name (the transverse) for the foramen, that transmits the vertebral artery in the cervical vertebra (page 229, nth line) ; the probable office of the mesenteric glands (page 267) ; origin of the lymphatic vessels (page 261) ; something new in regard to the thyroid gland (last third of page 391); a name (line of beauty) in place of the “inner lip of the crest of the ilium” (middle of page 112) ; and to use the term facial canal, in place of the improper term, aquaaductus Fallopii, for the canal which transmits the facial nerve (lower part of page 58.) Cynosure Publishing Company. Per G. D. TESTIMONIALS. Boston, January, 1887. To George Dutton, A.M., M.D., author of '■'■Illustrated Anatomy": Esteemed Sir,—Possessing a copy of your portly volume on Anatomy, which from time to time I have read and compared with similar works by other authors, I deem it my duty to inform you that in my opinion your book stands “at the head of the class.” All difficult, and often apparently meaningless terms, you render (within a parenthesis) into the plainest English language, so that the common sense of the un-Latinized student of human nature and the non-medically educated reader as well, can immediately (without recourse to a dictionary) comprehend the full and instructive significance of the otherwise mysterious technical phraseology. And thus, my esteemed sir, you have given the world a book within a book,— a com- plete work on the fearful and wonderful organization of man and woman, and em- bodying an ample parenthetical dictionary in pure English. All medical students should possess your reliable text volume, for they would become truly educated. They would from your carefully written pages derive intellectual wealth, and not, as is too frequently the fact, depend upon a retentive memory for success. And furthermore, I feel to thank you, in behalf of humanity, for the profound, philosophical, and reverential dignity and beauty which pervade your attractive pages. The human mind, clothed in its material organism, you exalt without touch- ing upon the metaphysical. The physical mechanism you exalt to the high station of mind. A path of light is thrown upon every page of your admirable volume. The reader sees in the structures and functions of the ponderous body, the love and wisdom of the Eternal Mind. He comprehends scientifically and philosophically that man’s immortal spirit lives in the organism, as a king in his own palace. Your volume would educate any careful reader, medical or non-medical, because of your numerous fine illustrations and exact verbal descriptions. My impression is that you were wisely influenced in the preparation of your Illustrated Anatomy, and I wish for you, what I feel you will have, an abundant reward. Ever, with high esteem, your friend, Andrew Jackson Davis, M.D. Dear Sir,—Your work on Anatomy is the best I have met with. It has a clear and effective style, and makes the study of human anatomy as interesting as novel reading; with one perusal of your work, one knows more about the structure of the human organism than if he had studied a year under any other author. It is especially adapted for popular use. To George Dutton, A.M., M.D. S. Roscoe, M.D., Oldham, Englafid. From the Emerson College of Oratory, Boston, Mass. We consider Dutton’s Anatomy the most readable, and for the general student the most useful, of any in the English language. It has been adopted as a book of refereiice, and is so used in our College. C. W. Emerson, President. H. C. Southwick, Secretary. APPENDIX. 25 Odd Fellows’ Library, Boston, Jan. 16, 1887. George Dutton, A.M., M.D.: Dear Sir,—At the regular annual meeting of the Board of Library Trustees, January, 1887, Francis Hayden, P. G., and Trustee of Library, presented in the name of the author a physiological work of rare value, entitled “Anatomy: Scientific and Popular,” by George Dutton, A.M., M.D. The Board accepted the same, and it was voted, “That the Secretary be directed to notify the generous donor of the action of the Board, and to tender to him the most cordial and heartfelt thanks for his val- uable donation to the Library.” I take great pleasure, sir, in transmitting to you the unanimous expression of the gratitude of the Trustees; and will you permit me to say that personally I am under great obligations to you for your thoughtful kind- ness in placing so comprehensive and scholarly a work where it will be of so much service. Competent judges have already examined it, and pronounce it in every way an invaluable addition to the Library. I have the honor to be, sir, in the name of and for the Board of Library Trus- tees, your very obedient and obliged servant, George H. Boynton, Secretary and Librarian. Melrose, Mass., Sept. 15, 1886. Geo. Dutton, M.D.: Dear Sir,—I have examined your “Anatomy” very thoroughly, and with much satisfaction. You have certainly accomplished your purpose, and given to the world a work on the structure of the human body that is intelligible and read- able. The retention of technical terms, with their meanings, renders the work popular, while at the same time it is scientific. The simplicity of the style, the avoidance of all useless verbiage, the great number of illustrations, which show every part of the body, render the work invaluable to the general reader, as well as to that large class of the community aspiring to physical improvement as necessary to the development of the soul. “ Know ye not that your bodies are the temples of the Holy Ghost,” is an utterance still pressing itself on the conscience of the thoughtful, whose desire is to be so well informed and so grandly trained, that they may know personally of “ the indwelling God.” To all such earnest, honest seekers, your book will be worth more than your asking price. I hope it may have so large a sale as to induce the writing and publishing of similar works on Physiology and Hygiene. Yours very truly, Mary A. Livermore.