.; ■ if i^j\ -■■■.'"•«' 1 • '"Wt i j,j,r.'.l:!,..fv;.;^ ,;|.ii! • \m p 'I • ANATOMY, DESCRIPTIVE AND SURGICAL. ANATOMY DESCRIPTIVE AND SURGICAL. HENRY .&RAY, F.R.S., LECTURER ON ANATO_MY AT ST. GEORGE'S HOSPITAL. THE DRAWINGS B Y H. V. CARTER, M. D., LATE DEMONSTRATOR OF ANATOMY AT ST. GEORGE'S HOSPITAL. THE DISSECTIONS JOINTLY BY THE AUTHOR AND DR. CARTER. WITH THREE HUNDRED AND SIXTY-THREE ENGRAVINGS ON WOOD. #C7/Vr ' PHILADELPHIA: BLANCHARD AND LEA. 18 59. 4- C. SHERMAN & SON, PRINTERS, Corner Seventh and Cherry Streets,Philadelphia TO SIR BENJAMIN COLLINS BRODIE, BART., F.RS., D.C.I,, SERJEANT-SURGEON TO THE QUEEN, CORRESPONDING MEMBER OP THE INSTITUTE OP PRANCE, fe Waxlt w MMtt, IN ADMIRATION OF HIS GREAT TALENTS, AND IN REMEIV1BRANCE OF MANY ACTS OF KINDNESS SHOWN TO THE AUTHOR, FROM AN EARLY PERIOD OF HIS PROFESSIONAL CAREER. AMERICAN PUBLISHERS' NOTICE. A FTER arranging for an early republication of this volume, it was found that the London Edition contained numerous typographical errors, which, though perhaps inseparable from the first issue of a large and elaborate work of this character, and though individually of minor importance, might yet prove trouble- some to the student. Its passage through the press has therefore been superin- tended by a competent professional gentleman, whose watchful scrutiny, it is hoped, has secured the correctness so essential to a work intended both for study and reference. While no additions to the text have been found necessary, some improvements in the arrangement have been introduced, among which the Index may be mentioned as much more convenient than that of the English edition. The novel plan of the work, and the high character which it has already acquired, have stimulated the Publishers to render it in every respect worthy the confidence of both teachers and students, and neither care nor expense has been spared to secure that result. Philadelphia, June, 1859. PREFACE. nHITIS work is intended to furnish the Student and Practitioner with an accurate view of the Anatomy of the Human Body, and more especially the application of this science to Practical Surgery. One of the chief objects of the Author has been, to induce the Student to apply his anatomical knowledge to the more practical points in Surgery, by introducing, in small type, under each subdivision of the work, such observations as show the necessity of an accurate knowledge of the part under examination. Osteology. Much time and care have been devoted to this part of the work, the basis of anatomical knowledge. It contains a concise description of the anatomy of the bones, illustrated by numerous accurately lettered engravings, showing the various markings and processes on each bone. The attachments of each muscle are shown in dotted lines (after the plan recently adopted by Mr. Holden), copied from recent dissections. The articulations of each bone are shown on a new plan ; and a method has been adopted, by which the hitherto complicated account of the development of the bones is made more simple. The Articulations. In this section, the various structures forming the joints are described; a classification of the joints is given, and the anatomy of each care- fully described: abundantly illustrated by engravings, all of which are taken from, or corrected by, recent dissections. The Muscles and Faseitv. In this section, the muscles are described in groups, as in ordinary anatomical works. A series of illustrations, showing the lines of incision necessary in the dissection of the muscles in each region, are introduced, and the muscles are shown in fifty-seven engravings. The Surgical Anatomy of the muscles in connection with fractures, and of the tendons or muscles divided in operations, is also described and illustrated. The Arteries. The course, relations, and Surgical Anatomy of each artery are described in this section, together with the anatomy of the regions containing the arteries more especially involved in surgical operations. This part of the work is illustrated by twenty-nine engravings. Vlll PREFACE. The Veins are described as in ordinary anatomical works; and illustrated by a series of engravings, showing those in each region. The veins of the spine are described and illustrated from the well-known work of Breschet. The Lymphatics are described, and figured in a series of illustrations copied from the elaborate work of Mascagni. The Nervous System and Organs of Sense. A concise and accurate description of this important part of anatomy has been given, illustrated by sixty-three en- gravings, showing the spinal cord and its membranes ; the anatomy of the brain, in a series of sectional views; the origin, course, and distribution of the cranial, spinal, and sympathetic nerves; and the anatomy of the organs of sense. The Organs of Digestion, of Circulation, of Voice and Respiration, and the Uri- nary and Generative Organs. A detailed description of this essential part of anatomy has been given, illustrated by fifty-three large and accurately lettered engravings. Regional Anatomy. The anatomy of the perinseum, of the ischio-rectal region, and of femoral and inguinal hernise, is described at the end of the work; the region of the neck, the axilla, the bend of the elbow, Scarpa's triangle, and the popliteal space, in the section on the arteries; the laryngotracheal region, with the anatomy of the trachea and larynx. These regions are illustrated by many engravings. Microscopical Anatomy. A brief account of the microscopical anatomy of some of the tissues, and of the various organs, has also been introduced. The Author gratefully acknowledges the great services he has derived, in the execution of this work, from the assistance of his friend, Dr. H. V. Carter late Demonstrator of Anatomy at St. George's Hospital. All the drawings, from which the engravings Avcre made, were executed by him. In the majority of cases, they have been copied from, or corrected by, recent dissections, made jointly by the Author and Dr. Carter. The Author has also to thank his friend, Mr. T. Holmes, for the able assistance afforded him in correcting the proof-sheets in their passage through the press. The engravings have been executed by Messrs. Butterworth and Heath; and the Author cannot omit thanking these gentlemen for the great care and fidelity displayed in their execution. Wilton Street, Belgkaye Square, August, 185^. CONTENTS. Osteology. General Properties of Bone, Chemical Composition of Bone, Structure of Bone, Form of Bones,. Vessels of Bone, Development of Bone, Growth of Bone, The Skeleton, . The Spine. General Characters of the Vertebras, Characters of the Cervical Vertebras, Atlas,..... Axis, . Vertebra Prominens,. Characters of the Dorsal Vertebras, Peculiar Dorsal Vertebras,. Characters of the Lumbar Vertebras, Structure of the Vertebras, Development of the Vertebras, . Atlas, Axis,. 7th Cervical, Lumbar Vertebras, Progress of Ossification in the Spine, False Vertebras, The Sacrum, The Coccyx, Development of the Coccyx, Of the Spine in general, . The Skull. Bones of the Cranium, Occipital Bone, . Parietal Bones, . Frontal Bone, Temporal Bones, Sphenoid Bone, . Sphenoidal Spongy Bones, . Ethmoid Bone, . Wormian Bones, Bones of the Face, . Nasal Bones, Superior Maxillary Bones, . Lachrymal Bones, Malar Bones, Palate Bones, Inferior Turbinated Bones. Vomer, .... Inferior Maxillary Bone, Articulations of the Cranial Bones, Sutures of the Skull, Vertex of the Skull, . PAGE 1 1 2 2 3 3 4 4 Base of the Skull, Internal Surface, Anterior Fossa, Middle Fossa,. Posterior Fossa, Base of Skull, External Surface, Lateral Regions of the Skull, Temporal Fossas, Zygomatic Fossas, Spheno-maxillary Fossa, . Anterior Region of Skull, . Orbits, .... Nasal Fossas, Os Hyoides, The Thorax. The Sternum, . Development of the Sternum, The Ribs, .... Peculiar Ribs, . Costal Cartilages, The Pelvis. Os Innominatum, .... Ilium, ...... Ischium, ..... Pubes,...... Development of the Os Innominatum, Boundaries of Pelvis, Position of Pelvis, .... Axes of Pelvis,..... Differences between the Male and Female Pelvis,...... The Upper Extremity. The Clavicle, The Scapula, Development of the Scapula, The Humerus, . Development of the Humerus The Ulna,.... Development of the Ulna, . The Radius, Development of the Radius, The Hand, The Carpus, Bones of Upper Row,. Bones of Lower Row, The Metacarpus, Peculiar Metacarpal Bones, Phalanges, Development of the Hand, The Femur, The Lower Extremity. Ill CONTENTS. Development of the Femur The Leg, . Patella, Tibia, Development of Tibia, Fibula, Development of Fibula, The Foot, . Tarsus, Os calcis, . Cuboid, PAGE 115 115 116 116 120 120 122 122 122 122 124 Astragalus, Scaphoid, . Internal Cuneiform, . Middle Cuneiform, External Cuneiform, . Metatarsal Bones, Peculiar Metatarsal Bones, Phalanges, Development of the Foot, Sesamoid Bones, PAGE 125 127 127 128 128 129 129 130 130 131 The Articulations. General Anatomy of the Joints Cartilage, . Fibro-cartilage, . Ligament, . Synovial Membrane, Forms of Articulation, Synarthrosis, Amphiarthrosis, . Diarthrosis, Movements of Joints, Gliding Movement, Angular Movement, Circumduction, . Rotation, Articulations of the Trunk. Articulations of the Vertebral Column, Atlas with the Axis, Atlas with the Occipi tal Bone, Axis with the Occipi tal Bone, Temporo-maxillary Articulation, Articulations of the Ribs with the Vertebras Costo-vertebral, . Costo-transverse, Costo-sternal Articulations, Intercostal Articulations, . Ligaments of the Sternum, 133 133 133 134 134 135 135 136 136 138 138 138 138 138 138 141 143 144 145 147 147 148 150 151 151 Articulation of the Pelvis with the Spine, Articulations of the Pelvis, Sacrum and Ilium, Sacrum and Ischium, Sacrum and Coccyx, Interpubic,. Articulations of the Upper Exti Sterno-clavicular, Scapuloclavicular, Proper Ligaments of the Scapula, Shoulder Joint, .... Elbow Joint, .... Radio-ulnar Articulation, . Wrist Joint, .... Articulations of the Carpus, Carpo-metacarpal Articulations, Metacarpophalangeal Articulations, Articulation of the Phalanges, . emity Articulations of the Lower Exti Hip Joint,..... Knee Joint, .... Articulations between the Tibia and Fibula Ankle Joint, .... Articulations of the Tarsus, Tarso-metatarsal Articulations, . Articulations of the Metatarsus, Metatarso phalangeal Articulations, Articulations of the Phalanges, . emity 152 153 153 154 154 155 156 158 159 160 161 163 164 166 168 169 170 170 172 176 178 180 183 183 184 184 Muscles and Fasciae. General Anatomy of Muscles, Fascias, 185 186 Muscles and Fascia of the Head axd Face. . 187 Subdivision into Groups, . Epicranial Region. Dissection, .... Fascia of Head, Occipito-Frontalis and its actions, Auricular Region. Dissection, .... Attollens Aurem, Attrahens Aurem, Retrahens Aurem, Actions,..... Palpebral Region. Dissection, .... Orbicularis Palpebrarum, . Corrugator Supercilii, 188 188 188 190 190 190 191 191 191 191 Tensor Tarsi, ..... Actions, ...... Orbital Region. Dissection, ..... Levator Palpebras, .... Rectus Superior ; Inferior, Internal, and Ex ternal Recti, ..... Superior Oblique, .... Inferior Oblique, .... Actions, .... Surgical Anatomy, .... Nasal Region. Pyramidalis Nasi, .... Levator Labii Superioris Alasque Nasi, Dilator Naris, Anterior and Posterior, Compressor Nasi, Narium Minor, Depressor Alas Nasi, ..." Actions, ..... 192 192 192 192 193 193 194 194 194 195 195 195 195 195 195 195 CONTENTS. XI Superior Maxillary Region. PAGE Levator Labii Superiorus Proprius, . .196 Levator Anguli Oris, . . . .196 Zygomaticus Major, ..... 196 Zygomaticus Minor, ..... 196 Actions,.......196 Inferior Maxillary Region. Dissection, ...... 196 Levator Labii Inferioris, . . . .196 Depressor Labii Inferioris, . . .197 Depressor Anguli Oris, .... 197 Actions,.......197 Intermaxillary Region, Dissection,......197 Orbicularis Oris,.....197 Buccinator,......198 Risorius,.......198 Actions,...... 19;* Temporo-maxillary Region. Masseter,.......198 Temporal Fascia,.....199 Dissection of Temporal Muscle, . .199 Temporal,......200 Pterygo-maxillary Region. Dissection,......200 Internal Pterygoid, ..... 200 External Pterygoid, ..... 201 Actions, . . . . . . .201 Muscles axd Fasciae of the Neck. Subdivision into Groups, . . . .201 Superficial Region. Dissection,......202 Superficial Cervical Fascia, . . . 202 Platysma Myoides,.....202 Deep Cervical Fascia, .... 203 Sterno-eleido mastoid, .... 204 Boundaries of the Triangles of the Neck, . 204 Actions, . . . . v . . . 205 Infrahyoid Region. Dissection,......205 Sterno-hyoid,......205 Sterno-thyroid, Thyro-hyoid, . . . 206 Omo-hyoid,......207 Actions,.......207 Suprahyoid Region. Dissection, ...... 207 Digastric, ....... 207 Stylo-hyoid, Mylo-hyoid, .... 20,^ Genio-hyoid,......208 Actions,.......209 Lingual Region. Dissection,......209 GenioJiyo-glossus,.....209 Hyo-glossus, Lingualis, . . . .210 Stylo-glossus, Palato-glossus, . . .210 Actions,.......211 Pharyngeal Region. Dissection,......211 Inferior Constrictor, . . . . .211 Middle Constrictor, Superior Constrictor, . 212 Stvlo-pharyngeus,.....212 Actions,.......212 Palatal Region. Dissection, .... Levator Palati, .... Tensor Palati, Azygos Uvulas, . Palato-glossus, Palato-pharyngeus, Actions, ..... Surgical Anatomy, Vertebral Region (Anterioi Rectus Capitis Anticus Major Rectus Capitis Anticus Minor Rectus Lateralis, Longus Colli, Vertebral Region (lateral). Scalenus Anticus, Scalenus Medius, Scalenus Posticus, Actions, ..... Musci.es axd Fascle of the Tru Subdivision into Groups, . Muscles of the Back Subdivision into Layers, First Layer. Dissection, .... Trapezius,..... Ligamentum Nuchas, Latissimus Dorsi, Second Layer. Dissection, ..... Levator Anguli Scapulas, . Rhomboideus Minor and Major, Actions,...... Third Layer. Dissection, ..... Serratus Posticus Superior and Inferior, Vertebral Aponeurosis, Splenius Capitis and Splenius Colli, . Actions, ...... Fourth Layer. Dissection, ..... Erector Spinas, ..... Sacro-lumbalis, ..... Musculus Accessorius ad Sacro-lumbalem, Cervicalis Ascendens, Longissimus Dorsi, .... Transversalis Colli, .... Trachelo-mastoid, .... Spinalis Dorsi, Spinalis Cervicis, Complexus, ..... Biventer Cervicis, .... Fifth Layer. Dissection, Semispinals Dorsi, Semispinalis Colli, Multifidus Spinas, Rotatores Spinas, Supraspinales, . Interspinals, . Extensor Coccygis, Intertransversales, Rectus Capitis Posticus Major and Minor, Obliquus Superior and Inferior, . Actions, ...... Muscles of the Abdomen. Dissection, ..... Obliquus Externus, .... PAGE 213 213 214 214 215 215 215 215 215 216 . 217 . 217 . 217 NTK. . 217 217,218 . 218 . 218 . 220 . 220 221 221 221 222 222 222 222 223 223 223 223 225 225 225 225 225 225 226 226 226 227 227 227 227 227 227 228 228 228 228 229 229 230 CONTENTS. Obliquus Internus,.....231 Transversalis,......233 Lumbar Fascia,.....233 Rectus Abdominis,.....234 Pyramidalis, Quadratus Lumborum, . . 235 Linea Alba, Lineas Semilunares, . 236 Lineas Transversas, . . . . .236 Actions,.......236 Muscles and Fascle of the Thorax. Intercostal Fasciae,.....237 Intercostales Interni et Externi, . . 237 Infracostales, Triangularis Sterni, . . 237 Levatores Costarum, ..... 238 Actions,.......238 Diaphragmatic Region. Diaphragm, ...... 238 Actions,.......240 Muscles axd Fasciae of the Upper Extremity. Subdivision into Groups, .... 241 Dissection of Pectoral Region and Axilla, . 242 Fascias of the Thorax, .... 242 Anterior Thoracic Region. Pectoralis Major, . . . . . 242 Costo-coracoid Membrane,.... 244 Pectoralis Minor, . . . . . 244 Subclavius, ...... 245 Actions,.......245 Lateral Thoracic Region. Serratus Magnus, ..... 246 Actions,.......246 Acromial Region. Deltoid,.......247 Actions, ....... 247 Anterior Scapular Region. Subscapular Aponeurosis, .... 247 Subscapulars, ...... 248 Actions,.......248 Posterior Scapidar Region. Supraspinous Aponeurosis, . . 248 Supraspinatus, ...... 248 Infraspinous Aponeurosis,.... 248 Infraspinatus, ...... 249 Teres Minor,......249 Teres Major,......250 Actions,.......250 Anterior Humeral Region. Deep Fascia of Arm, . 250 Coraco-brachialis, Biceps, .... 251 Brachialis Anticus, ..... 252 Actions,.......252 Posterior Humeral Region. Triceps,.......252 Subanconeus, ...... 253 Actions, ....... 253 Muscles of Forearm. Deep Fascia of Forearm, .... 253 Anterior Brachial Region. Superficial Layer. Pronator Radii Teres, .... 254 Flexor Carpi Radialis, .... 255 Palmaris Longus. . . . . .255 PAGE Flexor Carpi Ulnaris, .... 255 Flexor Sublimis Digitorum, . • • 255 Anterior Brachial Region, Deep Layer. Flexor Profundus Digitorum, . . . 256 Flexor Longus Pollicis, .... 257 Pronator Quadratus, ..... 257 Actions, ....... 258 Radial Region. Dissection, ...... 258 Supinator Longus, .... 258 Extensor Carpi Radialis Longior, . . 258 Extensor Carpi Radialis Brevior, . .259 Posterior Brachial Region, Superficial Layer. Extensor Communis Digitorum, . . 260 Extensor Minimi Digiti, .... 260 Extensor Carpi Ulnaris, .... 260 Anconeus, ...... 261 Posterior Brachial Region, Deep Layer. Supinator Brevis, ..... 261 Extensor Ossis Metacarpi Pollicis, . .261 Extensor Primi Internodii Pollicis, . . 261 Extensor Secundii, Internodii Pollicis, . 262 Extensor Indicis, ..... 262 Actions, ....... 263 Muscles and Fascia; of the Hand. Dissection, . . . . . .263 Anterior Annular Ligament, . . . 263 Posterior Annular Ligament, . . 263 Palmar Fascia, ...... 264 Muscles of the Hand. Radial Group,......264 Actions,.......266 Ulnar Region,......266 Actions, ....... 267 Middle Palmar Region, .... 267 Actions,.......268 Surgical Anatomy of the Muscles of the Upper Extremity. Fractures of the Clavicle, .... 268 Acromion Process, . . 269 Coracoid Process, . . 269 Humerus,.... 269 Ulna, . . . .271 Olecranon, . . .271 Radius, .... 271 ■ Muscles axd Fasciae of the Lower Extremity. Subdivision into Groups, .... 273 Iliac Region. Dissection, . 274 Iliac Fascia, . . . _ 274 Psoas Magnus, Psoas Parvus, . . . 275 [liacus, .... 275 Actions, . 276 Anterioi Dissection, Fascia? of the Thigh, Superficial'Fascia, Deep Fascia (Fascia Lata), Saphenous Opening, .... Iliac and Pubic Portions of Fascia Lata Tensor Vaginas Femoris, Sartorius, . Quadriceps Extensor Cruris, Rectus Femoris, Vastus Externus, . Femoral Region. CONTENTS. Xlll Vastus Internus and Crurasus, . Subcrurasus, . . Actions, ..... Internal Femoral Region Dissection, .... Gracilis, ..... Pectineus, Adductor Longus, Adductor Brevis, Adductor Magnus, Actions, ..... PAGE 2S0 2*0 280 281 281 2*2 282 2,S3 Gluteal Region. Dissection,......283 Glutasus Maximus, ..... 283 Glutasus Medius, ..... 2H4 Glutasus Minimus, ..... 285 Pyriformis, Obturator Internus, Gemelli, . 286 Quadratus Femoris, Obturator Externus, . 2S7 ■ Actions, ....... 287 Posterior Femoral Region. Dissection, . . .' . . 288 Biceps, Semitendinosus, .... 288 Semimembranosus, ..... 289 Actions,.......289 Surgical Anatomy of Hamstring Tendons, 289 Muscles and Fascia; of Leg. Dissection of Front of Leg, . . . 289 Fascia of the Leg, ..... 289 Muscles of the Leg, ..... 290 Anterior Tibiofibular Region. Tibialis Anticus,.....290 Extensor Proprius Pollicis, . . .291 Extensor Longus Digitorum, . . .291 Peroneus Tertius, . ... 291 Actions,.......291 Posterior Tibiofibular Region, Superficial Layer. Dissection of Back of Leg, . . . 292 Gastrocnemius, . . . . . .292 Soleus, Tendo Achillis, Plantaris, . . 293 Actions,.......293 Posterior Tibiofibular Region, Deep Layer. PAGE Deep Fascia of Leg,.....294 Popliteus, Flexor Longus Pollicis, . . 294 Flexor Longus Digitorum, Tibialis Pos- ticus, ....... 295 Actions,.......296 Fibular Region. Peroneus Longus, Peroneus Brevis, . . 296 Actions,.......297 Surgical Anatomy of Tendons around Ankle, .......297 Muscles and Fasciae of the Foot. Anterior Annular Ligament, . . . 297 Internal Annular Ligament, . . . 298 External Annular Ligament, . . . 298 Dissection of Sole of Foot, . .298 Plantar Fascia,......298 Muscles of the Foot, Dorsal Region. Extensor Brevis Digitorum, . . . 299 Actions,...... . 299 Plantar Region. Subdivision into Groups, .... 299 Subdivision into Layers, .... 299 First Layer, . . .299 Second Layer, . . .301 Third Layer, . . .302 Iuterossei,.......303 Surgical Anatomy of the Muscles of the Lower Extremity. Fracture of the Neck of the Femur, . the Femur below Trochanter Minor, . the Femur above the Con dyles, . the Patella, . the Tibia, the Fibula, with Dislocation of the Tibia inwards, . . 306 304 304 305 305 305 The Arteries. General Anatomy. into Pulmonary and Subdivision temic, . Distribution of—Where found, . Mode of Division—Anastomoses, Capillaries—Structure of Arteries, Sheath—Vasa Vasorum, . Aorta. Arch of Aorta Dissection, Ascending Part of Arch, Transverse Part of Arch, Descending Part of Arch, Peculiarities, Surgical Anatomy, Branches, . Peculiarities of Branches, Coronary Arteries. Sys Peculiarities, 307 307 307 308 308 309 310 310 311 312 312 313 313 313 Arteria Innominata. Relations, ...... Peculiarities, ..... Surgical Anatomy, .... . 314 . 314 . 314 Common Carotid Arteries. Course and Relations, Peculiarities, ..... Surgical Anatomy, .... . 315 . 317 . 318 External Carotid Artery. Relations,...... Surgical Anatomy, .... Branches, ...... . 319 . 319 . 319 Stiperior Thyroid Artery. Course and Relations, Surgical Anatomy, .... . 320 . 320 Lingual Artery. Course and Relations, Branches, ...... Surgical Anatomy, .... . 320 . 321 . 321 XIV CONTENTS. Facial Artery. PAGE 321 322 322 323 324 324 Course and Relations, Branches, ..... Peculiarities, .... Surgical Anatomy, . Occipital Artery. Course and Relations, Branches, . Posterior Auricular Artery. Branches,.......%25 Ascending Pharyngeal Artery. Branches, ...•••• 32o Temporal Artery. Course and Relations, Branches, ...-•• Surgical Anatomy, . Internal Maxillary Artery. Course and Relations, Peculiarities, ..... Branches from First Portion, Second Portion, . . Third Portion, . Surgical Anatomy of the Triangles of the Neck. Anterior Triangular Space. Inferior Carotid Triangle, .... Superior Carotid Triangle, Submaxillary Triangle, .... Posterior Triangular Space. Occipital Triangle, ..... Subclavian,...... Internal Carotid Artery. Cervical Portion, Petrous Portion, 325 326 326 326 327 327 328 329 330 330 331 331 332 Cavernous Portion, Cerebral Portion, Peculiarities, Surgical Anatomy, Ophthalmic Artery. Branches, .....•■ Cerebral Branches of Internal Carotid, Subclavian Arteries. First Part of Right Subclavian Artery, First Part of Left Subclavian Artery, Second Part of Subclavian Artery, Third Part of Subclavian Artery, Peculiarities, . . . • Surgical Anatomy, . Branches, ..... Vertebral Artery, Basilar Artery, . Spinal Branches of Vertebral, Cerebral Branches of Vertebral, Cerebellar Branches of Vertebral, Circle of Willis, . Thyroid Axis, . Suprascapular Artery, Transversalis Colli, Internal Mammary, . Superior Intercostal, Deep Cervical Artery, 332 333 334 334 334 334 334 336 338 339 340 340 341 341 342 343 344 344 344 344 344 345 345 345 346 347 347 Surgical Anatomy of the Axilla Axilla, its Boundaries, &c, Axillary Artery. First Portion, . Second Portion, Third Portion, . Peculiarities, Surgical Anatomy, . Branches, . Brachial Artery Relations, . Bend of the Elbow, . Peculiarities of Brachial Artery, Surgical Anatomy, . Branches, . Radial Artery Relations, . Deep Palmar Arch, . Peculiarities, Surgical Anatomy, Branches, . Ulnar Artery Relations, .... Superficial Palmar Arch, . Peculiarities of Ulnar Artery, Surgical Anatomy, Branches, . Descending Aorta Divisions, ..... Thoracic Aorta. Relations, ..... Surgical Anatomy, . Branches, . Abdominal Aorta. Relations, ..... Surgical Anatomy, Branches, . Cceliac Axis, Gastric Artery, . Hepatic Artery, . Splenic Artery, . Superior Mesenteric Artery Inferior Mesenteric Artery, Suprarenal Arteries, . Renal Arteries, . Spermatic Arteries, Phrenic Arteries, Lumbar Arteries, Middle Sacral Artery, Common Iliac Arteries Course and Relations, Peculiarities, .... Surgical Anatomy, Internal Iliac Artery. Course and Relations, Peculiarities, .... Surgical Anatomy, Branches, ..... Vesical Arteries, Middle Hemorrhoidal Arteries, Uterine and Vaginal Arteries, Obturator Artery, Internal Pudic Artery, PAGE 348 349 350 350 350 350 351 352 353 354 354 355 357 358 358 358 358 360 361 361 361 361 363 363 364 364 365 367 367 367 367 368 369 370 372 373 373 373 374 374 374 CONTENTS. PAGE Sciatic Artery,.....381 Gluteal, Ilio-lumbar, and Lateral Sa- cral Arteries, ..... 382 External Iliac Artery. Course and Relations, Surgical Anatoinv, Epigastric Artery, Circumflex Iliac Artery, . Femoral Artery. Course and Relations, Scarpa's Triangle, Peculiarities of Femoral Artery, Surgical Anatomy, . Branches, ..... Profunda Artery, Popliteal Artery. Popliteal Space, Course and Relations of the Artery, Peculiarities, .... Surgical Anatomy, Branches, ..... 382, 383 . 383 . 383 . 384 . 384 . 384 . 386 . 386 . 387 . 387 389 390 390 390 391 Anterior Tibial Artery. Course and Relations, 392 Peculiarities, ..... Surgical Anatomy. .... Branches, ...... PAGE . 392 . 393 . 393 Dorsalis Pedis Artery. Course and Relations, Peculiarities, ..... Surgical Anatomy, .... . 394 . 394 . 394 , 394 Posterior Tibial Artery. Course and Relations, Peculiarities, ..... Surgical Anatomy, .... Branches, ...... . 395 . 396 . 396 . 396 Peroneal Artery. Course and Relations, Peculiarities, ..... . 396 . 397 Plantar Arteries. Course and Relations, Plantar Arch and Branches, . 397 . 398 Pulmonary Artery. Course and Relations, . 399 The Veins. General Anatomy. Subdivision into Pulmonary, Systemic, and Portal, ....... 400 Anastomoses of Veins, .... 400 Superficial Veins and Deep Veins, or Venae Comites, ...... 400 Sinuses and their Structure, 400 Structure of Veins, ..... 401 Coats of Veins,...... 401 Valves of Veins, ..... 401 Vessels and Nerves of Veins, . 401 Veins of the Head and Neck. Facial Vein, ...... 402 Temporal Vein, ..... 403 Internal Maxillary Vein, .... 403 Temporo-maxillary Vein, .... 403 Posterior Auricular Vein, .... 404 Occipital Vein, ...... 404 Veins of the Neck. External Jugular Vein, .... 404 Posterior External Jugular Vein, 401 Anterior Jugular Vein, .... 401 Internal Jugular Vein, .... 405 Lingual, Pharyngeal, and Thyroid Veins, . 405 Veins of the Diploe, ..... 405 Cerebral Veins. Superficial Cerebral Veins, 40C>'7 per cent,: as is seen in the subjoined analysis by Berzelius:— Animal Matter, Gelatin and Bloodvessels, . . 33*30 /"Phosphate of Lime, . . . 5104 Inorganic \ Carbonate of Lime. . . . 11*30 or Fluoride of Calcium, . . . 2-00 Earthy Matter, J Phosphate of Magnesia, . . . 1*16 vSoda and Chloride of Sodium. . 120 3 10000 o OSTEOLOGY. The proportion between these two constituents varies at different periods of life, as is seen in the following table from Schrcger:— Child. Adult. Old Age. Animal Matter, . . . 47*20 .... 20-18 .... 12*2 Earthy Matter, .... 48*48 .... 74*84 .... 84*1 There are facts of some practical interest, bearing upon the difference here seen in the amount of the two constituents of bone, at different periods of life. Thus, in the child, where the animal matter forms nearly one-half of the weight of the bone, it is not uncommon to find, after an injury happening to the bones, that they become bent, or only partially broken, from the large amount of flexible animal matter which they contain. Again, also in aged people, where the bones contain a large proportion of earthy matter, the animal matter at the same time being deficient in quantity and quality, the bones are more brittle, their elasticity is destroyed; and, hence, fracture takes place more readily. Some of the diseases, also, to which bones are liable, mainly depend on the disproportion between the two constituents of bone. Thus, in the disease called rickets, so common in the children of scrofulous parents, the bones become bent and curved, either from the superincumbent weight of the body, or' under the action of certain muscles. This depends upon some deficiency of the nutritive system, by which bone becomes minus its normal proportion of earthy matter, whilst the animal matter is of unhealthy quality. In the vertebra of a rickety subject, Dr. Bostock found in 100 parts 7(J*75 animal, and 20*25 earthy matter. The relative proportions of the two constituents of bone are found to differ in different bones of the skeleton. Thus, the petrous portion of the temporal bone contains a large proportion of earthy matter, the bones of the limbs contain more earthy matter than those of the trunk, and those of the upper extremity a larger proportion than those of the lower. On examining a section of any bone, it is seen to be composed of two kinds of tissue, one of which is dense and compact in texture like ivory ; the other open, reticular, spongy, inclosing cancelli or spaces, and hence called spongy or cancel- lated tissue. The compact tissue is always placed on the exterior of a bone; the cancellous tissue is always internal. The relative quantity of these two kinds of tissue varies in different bones, and in different parts of the same bone, as strength or lightness is requisite. Form of Bones. The various mechanical purposes for which bones are employed in the animal economy require them to be of very different forms. All the scien- tific principles of Architecture and Dynamics are more or less exemplified in the construction of this part of the human body. The power of the arch in resisting superincumbent pressure is wTell exhibited in various parts of the skeleton, such as the human foot, and more especially in the vaulted roof of the cranium. Bones are divisible into four classes: Long, Short, Flat, and Irregular. The Long Bones are found chiefly in the limbs, where they form a system of levers, which have to sustain the weight of the trunk, and to confer extensive powers of locomotion. A long bone consists of a lengthened cylinder or shaft, and two extremities. The shaft is a hollow cylinder, the walls consisting of dense compact tissue of great thickness in the middle, and becoming thinner towards the extremities; the spongy tissue is scanty, and the bone is hollowed out in its interior to form the medullary canal. The extremities are generally somewhat expanded for greater convenience of mutual connection, and for the purposes of articulation. Here the bone is made up of spongy tissue with only a thin coating of compact substance. The long bones are the clavicle, humerus, radius, ulna, femur, tibia, fibula, metacarpal and metatarsal bones, and the phalanges. Short Bones. Where a part is intended for strength and compactness and the motion at the same time slight and limited, it is divided into a number of small pieces united together by ligaments, and the separate bones are short and coin- pressed, such as the bones of the carpus and tarsus. These bones, in their struc- GEN Ell A L ANATOMY OF BONE. 3 ture, are spongy throughout, excepting at their surface, where there is a thin crust of compact substance. Flat Bones. Where the principal requirement is either extensive protection, t or the provision of broad surfaces for muscular attachment, we find the osseous structure remarkable for its slight thickness, becoming expanded into broad flat plates, as is seen in the bones of the skull and shoulder-blade. These bones are composed of two thin layers of compact tissue, inclosing a layer of cancellous tissue of variable thickness. In the cranial bones, these layers of compact tissue are familiarly known as the tables of the skull; the outer one is thick and tough, the inner one thinner, denser, and more brittle, and hence termed the vitreous table. The intervening cancellous tissue is called the diploe. The flat bones are the occipital, parietal, frontal, nasal, lachrymal, vomer, scapula', and ossa inno- minata. The Irregular or Mired bones are such as, from their peculiar form, cannot be grouped under either of the preceding heads. Their structure is similar to that of other bones, consisting of an external layer of compact, and of a spongv can- cellous substance within. The irregular bones are the vertebra', sacrum,''coccyx, temporal, sphenoid, ethmoid, superior maxillary, inferior maxillary, palate, inferior turbinated, and hyoid. Vessels of Bone. The bloodvessels of bone are very numerous. Those of the compact tissue consist of a close and dense network of vessels, which ramify in a fibrous membrane termed the periosteum, which covers the entire surface of the bone in nearly every part. From this membrane, vessels pass through all parts of the compact tissue, running through the canals which traverse its substance. The cancellous tissue is supplied in a similar way, but by a less numerous set of larger vessels, which, perforating the outer compact tissue, are distributed to the cavities of the spongy portion of the bone. In the long bones, numerous apertures may be seen at the ends near the articular surfaces, some of which give passage to the arteries referred to; but the greater number, and these are the largest of them, are for the veins of the cancellous tissue which run separately from the arteries. The medullary canal is supplied by one large artery (or sometimes more), which enters the bone at the nutritious foramen (situated, in most cases, near the centre of the shaft), and perforates obliquely the compact substance. This vessel, usually accompanied by one or two veins, sends branches upwards and downwards, to supply the medullary membrane, which lines the central cavity and the adjoining canals. The ramifications of this vessel anastomose with the arteries both of the cancellous and compact tissues. The veins of bone are large, very numerous, and run in tortuous canals in the cancellous texture, the sides of which are constructed of a thin lamella of bone, perforated here and there for the passage of branches from the adjacent cancelli. The veins thus inclosed and supported by the hard structure, have exceedingly thin coats; and when the bony structure is divided, they remain patulous, and do not contract in the canals in which they are con- tained. Hence, the constant occurrence of purulent absorption after amputation, in those cases where the stump becomes inflamed and the cancellous tissue is infiltrated and bathed in pus. Lymphatic vessels have been traced into the sub- stance of bone. Nerves, also, accompany the nutritious arteries into their interior. Development of Bone. From the peculiar uses to which bone is applied, in forming a hard skeleton or framework for the softer materials of the body, and in inclosing and protecting some of the more important vital organs, we find its development takes place at a very early period. Hence, the parts that appear soonest in the embryo are the vertebral column and the skull, the great central column, to which the outer parts of the skeleton are appended. At an early period of embryonic life, the parts destined to become bone consist of a congeries of cells, which constitutes the simplest form of cartilage. This temporary cartilage, as it is termed, is an exact miniature of the bone which in due course is to take its place; and as the process of ossification is slow, and not completed until adult life, it increases in bulk by an interstitial development of new cells. The next step in 4 OSTEOLOGY. this process is the ossification of the intercellular substance, and of the cells composing the cartilage. Ossification commences in the interior of the cartilage at certain points, called points or centres of ossification, from which it extends into the surrounding substance. The period of ossification varies much in different bones. It commences first in the clavicle, in which the primitive point appears during the fifth week ; next in the lower jaw. The ribs also, and the long bones of the limbs, appear soon after. The number of ossific centres varies in different bones. In most of the short bones, it commences by a single point in the centre, and proceeds towards the circumference. In the long bones, there is a central point of ossification for the shaft or diaphysis; ami one for each extremity, the epiphyses. That for the shaft is the first to appear; those for the extremities appear later. For a long period after birth, a thin layer of unossified cartilage remains between the diaphysis and epiphyses, until their growth is finally com- pleted. Processes such as the trochanters that have separate centres of ossifi- cation, are called epiphyses previous to their union. Growth of Bone. Increase in the length of a bone is provided for by the development of new bone from either end of the shaft (diaphysis); and in the thickness, by the deposition of new matter upon the surface: but when growth is at an end, the epiphyses become solidly united to the ends of the diaphysis, and the bone is completely formed. A knowledge of the exact periods when the epiphyses become joined to the shaft, aids the surgeon in the diagnosis of many of the injuries to which the joints are liable; for it not unfrequently happens, that on the application of severe force to a joint, the epiphyses become separated from the shaft, and such injuries may be mistaken for fracture. The order in which the epiphyses become united to the shaft, follows a pecu- liar law, which appears to be regulated by the direction of the nutritious artery of the bone. Thus the arteries of the bones of the arm and forearm converge towards the elbow, and the epiphyses of the bones forming this joint become united to the shaft before those at the opposite extremity. In the lower extre- mities, on the contrary, the nutritious arteries pass in a direction from the knee; that is, upwards in the femur, downwards in the tibia and fibula; and in them it is observed, that the upper epiphysis of the femur, and the lower epiphyses of the tibia and fibula, become first united to the shaft. A diseased condition of any joint makes considerable variation in the period of development of the several bones which enter into its formation. Thus, in chronic inflammation occurring in a joint at an early period of life, the epiphysal cartilages take on premature ossification; this process proceeding so rapidlv, that it speedily becomes converted into bone, which becomes united to the shaft, and the bone ever after is considerably diminished in length: hence partial atrophy of the limb is the result. The entire skeleton in an adult consists of 206 distinct bones. These are Cranium, ......... 8 Ossicula auditus, ........ G Face,..........14 Vertebral column (sacrum and coccyx included), . . 20 Os hyoides, sternum, and ribs, ..... 26 Upper extremities, ....... G4 Lower extremities, ....... 62 206 In this enumeration, the sesamoid and Wormian bones are excluded as also are the teeth, which differ from bone both in structure, development, and mode of growth. The skeleton consists of a central column or Spine; of three great cavi- ties, the Skull, Thorax, and Pelvis; and of the Superior and Inferior Extremities. GENERAL CHARACTERS OF THE VERTEBRAE. THE SPINE. The Spine is a flexuous column, formed of a series of bones called Yeriebne. The vertebra? are divided into true and/W/V. The true vcrtebrjie are twenty-four in number, and have received the names co-viced, dorsal, and lumbar, according to the position which they occupy; seven being found in the cervical region, twelve in the dorsal, and five in the lumbar. The false vertebra}, nine in number, are firmly united, so as to form two bones, —five entering into the formation of the upper bone or sacrum', and four into the terminal bone of the spine or coccyx. !7 Cervical. 12 Dorsal. 5 Lumbar. False Vertebra?, 9 \ ',' ^a ' ( 4 Coccyx. General Characters of the Vertebr.e. Each vertebra consists of two parts, an anterior solid segment or body, forming the chief pillar of support; a posterior segment, the arch, forming part of a hollow cylinder for protection. The arch is formed of two pedicles and two laminae, supporting seven processes; viz., four articular, two transverse, and one spinous process. The Body is the largest and most solid part of a vertebra, serving to support the weight of the cranium and trunk. Above and below it is slightly concave, presenting a rim around its circumference; and its surfaces are rough, for the attachment of the intervertebral fibro-cartilages. In front it is convex from side to side, concave from above downwards; behind, flat from above downwards, and slightly concave from side to side. Its anterior surface is perforated by a few small apertures, for the passage of nutrient vessels; whilst on the posterior sur- face is a single irregular-shaped, or occasionally several large apertures, for the exit of veins from the body of the vertebra, the vena' basis vertebrce. The Pedicles project backwards, one on each side, from the upper part of the body of the vertebra, at the line of junction of its posterior and lateral surfaces; they form the lateral parts of the arch, which is completed posteriorly by the two laminae. The concavities above and below the pedicles are the interverte- bral notches; they are four in number, two on each side, the inferior ones being always the deeper. The Lamina' consist of two broad plates of bone, which complete the vertebral arch behind, inclosing a foramen which serves for the protection of the spinal cord; tbey are connected to the body through the intervention of the pedicles. Their upper and lower borders are rough, for the attachment of the ligamenta sub/lava. The Spinous Process projects backward from the junction of the two laminae, and serves for the attachment of muscles. The Transverse Processes, two in number, project one at each side from the point where the articular processes join the pedicle. They also serve for the attachment of muscles. The Articular Processes are four in number; two superior, the smooth surfaces of which are directed more or less backwards; and two inferior, the articular sur- faces of which look more or less forwards. Characters of the Cervical Vertebr.e (Fig. 1). The Body is smaller than in any other region of the spine, thicker before than behind, and broader from side to side than from before backwards. Its upper surface is concave transversely, and presents a projecting lip on each side; its lower b' OSTEOLOGY. surface being convex from side to side, concave from before backwards, and present- ing laterally a shallow^ concavity, which receives the corresponding projecting lip of the adjacent vertebra. The pedicles are directed obliquely outwards, and the superior intervertebral notches are slightly deeper, but narrower, than the inferior. The lamince are narrow, long, thinner above than below, and imbricated, i. e., overlapping each other; inclosing the foramen, which is very large, and of a triangular form. The spinous processes are short, bifid at the extremity, the two divisions being often of unequal size. They increase in length from the fourth to the seventh. The transverse processes are short, directed downwards, outwards, and forwards, bifid at their extremity, and marked by a groove along their upper surface, which runs dowmvards and outwards from the superior intervertebral notch, and serves for the transmission of one of the cervical nerves. The trans- verse processes are pierced at their base by a foramen, for the transmission of the vertebral artery, vein, and plexus of nerves. Each of these processes is formed by two roots: the anterior or smaller, which is attached to the side of the body, corresponds to the ribs in the dorsal region; the posterior is larger, springs from the pedicle, and corresponds to the true transverse processes. It is by the junc- tion of these two processes that the vertebral foramen is formed. The extremities of each of these roots form the anterior and posterior tubercles of the transverse Fij{ 1 —A Cervical Vertebra. Anterior Tuh rclt of Tra nsTroc. ■ ^ /'>v^=-"~~!'^dt%v- — ^ Ife Foramen for Vertebral ArT. '^ YostcrirrTulcrch of Trans. Fn Superior Articular Trorrsi In fcno -Arttctila r L'rociss processes. The articular processes are oblique: the superior are of an oval form, flattened, and directed upwards and backwards; the inferior downwards and forwards. The peculiar vertebra} in the cervical region are the first or Atlas;, the second or Axis; and the seventh or Vertebra prominens. The Atlas (Fig. 2) (so named from supporting the globe of the head). The chief Fig. 2.— ]st Cervical Vertebra, or Atlas. Tuberc/fi—-^lii --^ I'rans.Proc, j, •V-''■■«!*■>*«,, \ ,, To ra?//en for {Aril Qrooi-e fcr Ve/?■/•./<. A rt ? a ad 'if* Ccr v.Atrxus Sjpin. Proc. CERVICAL VERTEBRAE. 7 peculiarities of this bone are, that it has neither body, spinous process, nor pedicles. It consists of an anterior arch, a posterior arch, 'and two lateral masses. The anterior or lesser arch, which forms about one-fifth of the bone, represents the front part of the body of a vertebnc ; its anterior surface is convex, and presents about its centre a tubercle for the attachment of the Longus colli muscle; posteriorly it is concave, and marked by a smooth oval surface, for articulation with the odontoid process of the axis. The posterior or greater arch, which forms about two-fifths of the circumference of the bone, terminates behind a tubercle, which is the rudi- ment of a spinous process, and gives origin to the Rectus capitis posticus minor. The posterior part of the arch presents above a rounded edge ; whilst in front, immediately behind the superior articular processes, are two grooves, sometimes converted into foramina by delicate bony spicula. These grooves represent the superior intervertebral notches, and are peculiar from being situated behind the articular processes, instead of before them, as in the other vertebrae. They serve for the transmission of the vertebral artery, which, ascending through the foramen in the transverse process, winds around the lateral mass in a direction backwards and inwards. They also transmit the sub-occipital nerves. On the under surface of the posterior arch, in the same situation, are two other grooves, placed behind the lateral masses, and representing the inferior intervertebral notches of other vertebrae. They are much less marked than the superior. The lateral masses, which are the most bulky and solid parts of the Atlas, present two articulating pro- cesses above, and two below. The two superior are of large size, oval, concave, and approach towards one another in front, but diverge behind ; they are directed upwards, inwards, and a little backwards, forming a kind of cup for the condyles of the occipital bone, and are admirably adapted to the nodding movements of the head ; whilst the inferior, which are circular in form, and flattened, are directed downwards, inwards, and a little backwards, articulating with the axis, and per- mitting the rotatory movements. Just below the inner margin of each superior articular surface, is a small tubercle, for the attachment of a ligament which, stretching across the ring of the Atlas, divides it into two unequal parts; the anterior or smaller segment receiving the odontoid process of the Axis, the posterior allowing the transmission of the spinal cord and its membranes. This ligament and the odontoid process are marked in the figure in dotted outline. The transverse pro- cesses are of large size, long, not bifid, perforated at their base by a canal for the vertebral artery, which is directed from below, upwards and backwards. The Axis (Fig. 3) (so named from forming the pivot upon which the head Fig. 3—2d Cervical Vertebra, or Axis. Odontoid Prjc , Artie. Surf.forAtl.cs Spin. Froc.J Bodij Tra /is .Froe. Infer.-A 7 tic.Proa. rotates). The most distinctive character of this bone is the existence of a strong prominent process, tooth-like in form (hence the name odontoid), which arises per- pendicularly from the upper part of the body. The body is of a triangular form; 8 OSTEOLOGY its anterior surface deeper than the posterior presents a median longitudinal ridge, separating two lateral depressed surfaces for the attachment of the Longi colli muscles. The odontoid process presents two oval articulating surfaces : one in front, for articulation with the Atlas ; another behind, for the transverse ligament; the apex is pointed, and on either side of it is seen a rough impression for the attachment of the odontoid or check ligaments ; whilst the base, where attached to the body, is constricted, so as to prevent displacement from the transverse ligament, which binds it in this situation to the anterior arch of the Atlas. On each side of this process are seen the superior articular surfaces ; they are round, convex, directed upwards and outwards, and are peculiar in being supported on the body, pedicles, and transverse processes. The inferior articular surfaces, which are pos- terior and external to these, have the same direction as those of the other cervical vertebrae. The superior intervertebral notches are very shallow, and lie behind the articular processes ; the inferior in front of them, as in the other cervical vertebrae. The transverse processes are very small, not bifid, and perforated by the vertebral foramen, which is directed obliquely upwards and outwards. The laminae are thick and strong, and the spinous process is of large size, very strong, deeply chan- nelled on its under surface, and presenting a bifid, tubercular extremity for the attachment of muscles. Seventh Cervical. The most distinctive character of this vertebra is the exist- ence of a very large, lonjg, and prominent spinous process ; hence the name "Ver- tebra prominens." This process is thick, nearly horizontal in direction, not bifur- cated, and has attached to it theligamentum nuchae. The foramina in the transverse processes are small, often wanting, and when present do not give passage to the vertebral artery ; their upper surface presents only a slight groove, and generally only a trace of bifurcation at their extremity. Characters of the Dorsal Vertebrae. The Dorscd Vertebree (Fig. 4) are intermediate in size between the cervical and lumbar. The body is somewhat triangular in form, broader in the antero-posterior Superior Artie. Troccss Fig. 4.—A Dorsal Vertebra Bend facet for Jiecid ojRxb Facet for Tubercle ofRih-^ De m ifacet for Jiea d of R11 Infer. A rtic .Troc. than in the lateral direction, more particularly in the middle of the dorsal region, thicker behind than in front, flat above and below, deeply concave behind, and marked on each lateral surface, near the root of the pedicle, by two demi-facets, one above, the other below. These are covered with cartilage in the recent state •' and when DORSAL VERTEBRAE. 9 articulated with the adjoining vertebrae, form oval surfaces for the reception of the heads of the corresponding ribs. The pedicles are strong, and the inferior intervertebral notches of large size. The laminae are broad and thick, and the spinal foramen small, and of a round or slightly oval form. The articular surfaces are flat, the superior being directed backwards and a little outwards and upwards, the inferior forwards and a little inwards and downwards. The transverse processes are thick, strong, and of great length, directed obliquely backwards and outwards, presenting a clubbed extremity, lipped on its anterior part by a small concave surface for articulation with the tubercle of a rib. The spinous processes are long, directed obliquely downwards, and terminated by a tubercle. The peculiar dorsal vertebrae are the first, ninth, tenth, eleventh, and twelfth (Fig- 5). Fig. 5.—Peculiar Dorsal Vertebra?. An entire facet tthot'e A Dctm face t I el a w A Demi'-facet/ trSove —One entire ferret, A Tl r/itt re fn ret Vofacet on Tretns. I'sor. which is n/di i/icnfa r,/ n entire fleet No facet on Trail $2"' Infer.Artie. Pros con uejcand turntJ outward The First ]><>rsal Vertebra may be distinguished by the existence on each side of the body of a single entire articular facet for the head of the first rib, and a 10 OSTEOLOGY. half facet for the upper half of the second. The upper surface of the body is like that of a cervical vertebra, being broad transversely, concave, and lipped on each side. The superior articular surfaces are oblique, and the spinous process thick, long, and almost horizontal. The Ninth Dorsal has no demi-facet below. The Tenth Dorsal has an entire articular facet at each side above; no demi- facet below. In the Eleventh Dorsal, the body approaches in its form to the lumbar; and has a single entire articular surface on each side. The transverse processes are very short, and have no articular surfaces at their extremities. The Twelfth Dorsal has the same characters as the eleventh; but _may be distinguished from it by the transverse processes being quite rudimentary, and the inferior articular surfaces being convex and turned outwards, like those of the lumbar vertebrae. The smallest dorsal vertebra is the fourth. The vertebrae increase in size from that point downwards to the twelfth, and upwards to the first. The spinous processes also, from the eighth downwards, become shorter, and are directed more horizontally. Characters of the Lumbar Vertebrae. The Lumbar Vertebrae (Fig. 6) are the largest segments of the vertebral column. The Body is large, broad from side to side, flat above and below, and thicker Fig. C).—A Lumbar Vertebra. before than behind. The pedicles are very strong, directed backwards; and the inferior intervertebral notches are of large size. The laminae are short, but broad and strong; and the foramen triangular, larger than in the dorsal, smaller than in the cervical region. The superior articular processes are concave, and directed backwards and inwards; the inferior, convex, and directed forwards and outwards. Projecting backwards from each of the superior articular processes is a tubercle, the representative of the transverse processes in the dorsal and cervical regions. The transverse processes are long, slender, directed a little backwards, and present, at the posterior part of their base, a small tubercle, which is directed downwards. The spinous processes are thick and broad, somewhat quadrilateral, horizontal in direction, and thicker below than above. The Fifth Lumbar vertebra is peculiar from having the body much thicker in front than behind, which accounts for the prominence of the sacro-vertebral articulation. Structure of the Vertebras. The structure of a vertebra differs in different parts. The Body is composed almost entirely of light spongy cancellous tissue, having a thin coating of compact tissue on its external surface, permeated throughout its interior with large canals for the reception of veins, which converge towards a DEVELOPMENT OF THE VERTEBRAE. 11 single large irregular or several small apertures at the posterior part of the body of each bone. The arch and processes projecting from it have, on the contrary. an exceedingly thick covering of compact tissue. I>cvclopment. Each vertebra is formed of three primary centres of ossification (Fig. 7), one for each lamella and its processes. and one for the body. Those for the lamellae appear about the sixth week of fcetal life, in the situation where the transverse processes afterwards project, the ossific granules shooting back- wards to the spine, forwards to the body, and outwards into the transverse and articular pro- cesses. That for the body makes its appearance in the middle of the cartilage about the eighth week. At birth, these three pieces are perfectly separate. During the first year, the lateral portions become partly united behind, in the situation of the spinous process, and thus the arch is formed. About the third year, the body is joined to the arch on each side in such a man- ner, that the body is formed from the three original centres of ossification. Before puberty, no other changes occur except- ing a gradual increase of growth of these primary centres, the upper and under surface of the bodies, and the ends of the trans- verse and spinous processes be- ing tipped with cartilage, in which ossific granules are not as yet deposited. At sixteen years (Fig. 8), four secondary centres appear, one for the tip of each transverse process, and two (sometimes united into one) for the spinous process. At twenty- one years (Fig. !>), two thin cir- cular plates of bone are formed, one for the upper, and one for the under surface of the body. All these become joined, and the bone is completely formed, about the thirtieth year of life. Exceptions to this mode of development occur in the first, second, and seventh cervical, and in those of the lumbar region. Fiiz. 7.—Development of a Vertebra. By o ?'?*ii/nary centres 1 for Body {&*?> wee.l) 2. no me tun 2 add it F Spi n. nroc (1o y .r*J /.d.ites 1 for iip-pe r su rfa e of body I'll r> 1'for it tide r sit rf mo J /for t,acA la tcraI tin. is (C$ „,0.) -Lumbar Vertebra. adJiftoiial crnt re* fur lutiertlct an Srp.Artie.Pore. 1*2 OSTEOLOGY. The Atlas (Fig. 10) is developed by three centres ; one (sometimes two) for the anterior arch, and one for each lateral mass. The ossific centres for each lateral mass commence before birth. At birth, the anterior arch is altogether cartilaginous, and the two lateral pieces are separated from one another behind. The nucleus for the anterior arch appears in the first year, between the second and third years the two lateral pieces unite, and join the anterior part at the age of five or six years. There is frequently a separate epiphysis for the rudimentary spine. The Axis (Fig. 11) is developed by five centres; three for its anterior part, and two for the posterior. The three anterior centres are, one for the lower part of the body, and two for the odontoid process and upper part of the body ; the two posterior ones are, one for each lamella. At about the sixth month of foetal life, those for the body and odontoid process make their appearance, the two for the odontoid process joining before birth. At birth the bone consists of four pieces, two anterior and two lateral. At the fourth year the body and odontoid process are completely joined. The Seventh Cervical. The anterior or costal part of the transverse process of the seventh cervical is developed from a separate osseous centre at about the sixth month of foetal life, and joins the body and posterior division of the trans- verse process between the fifth and sixth years. Sometimes this process continues as a separate piece, and becoming lengthened outwards, constitutes what is known as a cervical rib. The Lumbar Vertebras (Fig. 12) have two additional centres (besides those peculiar to the vertebrae generally), for the tubercles, which project from the back part of the superior articular processes. The transverse process of the first lumbar is sometimes developed as a separate piece, which may remain permanently uncon- nected with the remaining portion of the bone ; thus forming a lumbar rib, a pecu- liarity which is sometimes, though rarely, met with. Progress of Ossification in the Spine Generally. Ossification of the laminae of the vertebrae commences at the upper part of the spine, and proceeds gradually downwards ; hence the frequent occurrence of spina bifida in the lowTer part of the spinal column. Ossification of the bodies, on the other hand, commences a little below the centre of the spinal column, and extends both upwards and downwards. Although, however, the ossific nuclei make their first appearance in the lower dorsal vertebrae (about the ninth), the lumbar and first sacral are those in which these nuclei are largest at birth. The False Vertebra. The False Vertebra^ consist of nine pieces, wdiich are united so as to form two bones, five entering into the formation of the sacrum, four the coccyx. The Sacrum (Fig. 13) is a large triangular bone, situated at the lower part of the vertebral column, and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two ossa innominata; its upper part, or base, articulating with the last lumbar vertebra, its apex with the coccyx. The sacrum is curved upon itself, and placed very obliquely, its upper extremity projecting forwards, forming, with the last lumbar vertebra, a very prominent angle, called the pro)nontory or sacro-vertebral ancjle, whilst its central part is directed backwards, so as to give increased capacity to the pelvic cavity. It pre- sents for examination an anterior and posterior surface, two lateral surfaces, a base, an apex, and a central canal. The Anterior Surface is deeply concave from above downwards, and slightly so from side to side. In the middle are seen four transverse lines, indicating the original division of the bone into five separate pieces. The portions of bone inter- vening between the lines correspond to the bodies of the vertebrae; they are slightly concave longitudinally, and diminish in size from above downwards. At the ex- tremities of each of these lines, are seen the anterior sacral foramina, analogous to the intervertebral foramina, four in number on each side, somewhat rounded in SACRUM. 13 form, diminishing in size from above downwards, and directed outwards and for- wards ; they transmit the anterior branches of the sacral nerves. External to these foramina is the lateral mass, formed by the coalesced transverse processes Fig. 13.—Sacrum. Anterior Surface of the sacral vertebrae, traversed by four broad shallow grooves, which lodge the anterior sacral nerves as they pass outwards, the grooves being separated by pro- minent ridges of bone, which give attachment to the slips of the Pyriformis muscle. The Posterior Surface (Fig. 14) is convex, and much narrower than the ante- rior. In the middle line, are three or four tubercles, sometimes connected together, which represent the rudimentary spinous processes. Of these tubercles, the first is usually very prominent, and perfectly separate from the rest; the second, third, and fourth, existing either separate, or united into a ridge, which diminishes in size as it descends ; the fifth, and sometimes the fourth, remaining undeveloped, and exposing below, the lower end of the sacral canal. External to the spinous processes on each side, are the lamina?, broad and well marked in the three first pieces ; the lower part of the fourth, and the whole of the fifth, being undeveloped : in this situation the sacral canal is exposed. External to the laminae are a linear series of indistinct tubercles representing the articular processes ; the upper pair are well developed ; the second and third are small; the fourth and fifth (usually blended together) are situated on each side of the sacral canal: they are called the sacral cornua, and articulate with the cornua of the coccyx. External to the articular processes are the four posterior sacral foramina ; they are smaller in size, and less regular in form than the anterior, and transmit the posterior branches of the sacral nerves. On the outer side of the posterior sacral foramina are a series of tubercles, representing the rudimentary transverse processes. The first pair of transverse tubercles are very distinct, and correspond with each superior 14 OSTEOLOGY. angle of the bone ; the second, small in size, enter into the formation of the iliac articulation; the third give attachment to the oblique sacro-iliac liga Fig. 14.—Sacrum. Posterior Surface. and the fourth and fifth to the great sacro-ischiatic ligaments. The interspace between the spinous and transverse process of the sacrum presents a wide shallo\v concavity, called the sacral groove ; it is continuous above with the vertebral groove, and lodges the origin of the Erector Spinae. The Lateral Surface, broad above, becomes narrowed into a thin edge below. Its upper half presents in front a broad ear-shaped surface for articulation with the ilium. This is called the auricular or ear-shaped surface, and in the fresh state is coated with cartilage. It is bounded posteriorly by deep and rough impres- sions, for the attachment of the sacro-iliac ligaments. The low^er half is thin and sharp, and gives attachment to the greater and lesser sacro-ischiatic ligaments; below, it presents a deep notch, which is converted into a foramen by articulation with the transverse process of the upper piece of the coccyx, and transmits the anterior branch of the fifth sacral nerve. The Base of the sacrum, which is broad and expanded, is directed upwards and forwards. In the middle is seen an oval articular surface, Avhich corresponds with the under surface of the body of the last lumbar vertebra, bounded behind by the large triangular orifice of the sacral canal. This orifice is formed behind by the spinous process and laminae of the first sacral vertebra, whilst projecting from it on each side are the superior articular processes ; they are oval, concave, directed backwards and inwards, like the superior articular processes of a lumbar vertebra. In front of each articular process is an intervertebral notch, which forms the lower half of the last intervertebral foramen. Lastly, on each side of the articular surface is a broad and flat triangular surface of bone, called the ah DEVELOPMENT OF SACRUM. 15 of the sacrum ; they extend outwards, and are continuous on each side with the iliac fossae. The Apex, directed downwards and forwards, presents a small oval concave surface for articulation with the coccyx. The Sacral Canal runs throughout the greater part of the bone ; it is laro*e and triangular in form above, small and flattened from before backwards below. In this_ situation, its posterior wall is incomplete, from the non-development of the laminae and spinous processes. It lodges the sacral nerves, and is perforated by the anterior and posterior sacral foramina, through which these pass out. Structure. It consists of much loose spongy tissue within, invested externally by a thin layer of compact tissue. Differences in the Sacrum of the Male and Female. The sacrum in the female is usually wider than in the male, and it is much less curved, the upper half of the bone being nearly straight, the lower half presenting the greatest amount of curvature. The bone is also directed more obliquely backwards; which increases the size of the pelvic cavity, and forms a more prominent sacro-vertebral angle. In the male the curvature is more evenly distributed over the whole length of the bone, and is altogether greater than in the female. Peculiarities of the sacrum. This bone, in some cases, consists of six instead of five pieces; occasionally the number is reduced to four. Sometimes the bodies of the first and second vertebrae are not joined, or the laminae and spinous processes have not coalesced with the rest of the bone. Occasionally the superior transverse tubercles are not joined to the rest of the bone on one or both sides ; and, lastly, the sacral canal may be open for nearly the lower half of the bone, in consequence of the imperfect development of the laminae and spinous processes. The sacrum also varies considerably with respect to its degree of curvature. From the examination of a large number of skeletons, it would appear, that, in one set of cases, Flg the anterior surface of this bone was y0, nearly straight, the curvature, which was very slight, affecting only its lower end. In another set of cases, the bone was curved throughout its whole length, but especially towards its middle. In a third set, the degree of curvature was less marked, and affected espe- cially the lower third of the bone. Development of Sacrum (Fig. 15). The sacrum, formed by the union of five vertebrae, has thirty-five centres of ossification. Each of the three first pieces is developed by seven centres; viz., three for the body, one for its central part, one for each epiphysal lamella on its upper and under surface, and one for each of the laminae : so far the first three sacral vertebrae, as wrell as the twro last, are developed like the other pieces of the vertebral column. One of the characteristic points in the development of this bone, consists in the existence of two ad- at ditional centres for each of the first three pieces, which appear one on each side, close to the anterior sacral foramina, and correspond to the trans- verse processes of the lumbar verte- brae. 15.—Development of Sacrum. 7ned ly union of 5 Vertebra. 2 characteristic points. 1 :**? 2 Additional centres for- the first 3 pieces * at berth 2"/ 2 Epivhysa-l la mince for each lateral surface 1G OSTEOLOGY. Each of the two last pieces is developed by five centres: three for the body; viz., one for its central part, and one for each of the epiphysal lamellae; and one for each of the laminae. A second characteristic point in the development of this bone consists in each lateral surface of the sacrum being developed by two epiphysal points, one for the auricular surface, and one for the thin lateral border of the bone. Period of Development. At about the eighth or ninth week of foetal life, ossifi- cation of the central part of the bodies of the three first vertebrae commences, and, at a somewhat later period, that of the two last. Between the sixth and eighth month ossification of the lamellae takes place ; and at about the same period the characteristic osseous tubercles for the three first sacral vertebrae make their appear- ance. The lateral pieces join to form the arch, and are united to the bodies, first, in the lowest vertebrae. This occurs about the second year, the uppermost seg- ment appearing as a single piece about the fifth or sixth year. About the six- teenth year the epiphysal lamellae for the bodies are formed ; and between the eighteenth and twentieth years those for each lateral surface of the sacrum make their appearance. About this period, the two last segments are joined to one another; and this process gradually extending upwards, all the pieces become united, and the bone completely formed from the twenty-fifth to the thirtieth year of life. Articulations. \Yith four bones ; the last lumbar vertebra, coccyx, and the two ossa innominata. Attachment of Muscles. The Pyriformis and Coccygeus on either side; behind, the Gdutaeus maximus and Erector Spinae. The Coccyx. The Coccyx (xoxzuz, "cuckoo"), so called from resembling a cuckoo's beak (Fig. 16), is formed of four small segments of bone, the most rudimentary parts of the vertebral column. Of these, the first is the largest, and often exists as a separate piece; the three last diminishing in size from above downwards, are blended together so as to form a single bone. The gradual diminution in the size of the pieces gives this bone a triangular form, articulat- ing by its base with the apex of the sacrum. It pre- sents for examination an anterior and posterior sur- face, two borders, a base, and an apex. The anterior surface is slightly concave, and marked with three transverse grooves, indicating the points of junction of the different pieces. It has attached to it the ante- rior sacro-coccygeal ligament and levator ani muscle, and supports the lower end of the rectum. The poste- rior surface is convex, marked by grooves similar.to those on the anterior surface, and presents on each side a linear row of tubercles, which represent the articular processes of the coccygeal vertebrae. Of these, the superior pair are very large; they are called the cornua of the coccyx, and projecting up- wards, articulate with the cornua of the sacrum, the junction between these two bones completing the fifth sacral foramen for the transmission of the posterior branch of the fifth sacral nerve. The lateral bor- ders are thin, and present a series of small eminences, which represent the transverse processes of the coc- cygeal vertebrae. Of these, the first on each side i? of large size, flattened from before backwards, and often ascends upwards to join the lower part of the thin lateral edge of the sacrum, thus completing the fifth sacral foramen : the others diminish in size from "tor ritcrior Surface. /-/ THE SPINE. 17 above downwards, and are often wanting. The borders of the coccyx are narrow, and give attachment on each side to the sacro- sciatic ligaments and Coccygeus muscle. The base presents an oval surface for articulation with the sacrum. The apex is rounded, and has attached to it the tendon of the external Sphincter ani muscle. It is occasionally bifid, and sometimes deflected to one or other side. Development. The coccyx is developed by four centres, one for each piece. Occasionally one of the three first pieces of this bone is developed by two centres, placed side by side. The periods wdien the ossific nuclei make their appearance are the following: in the first segment, at birth; in the second piece, at from five to ten years; in the third, from ten to fifteen years; in the fourth, from fif- teen to twenty years. As age advances, these various segments become united in the following order : the twro first pieces join, then the third and fourth; and, lastly, the bone is completed by the union of the second and third. At a late period of life, especially in females, the coccyx becomes joined to the end of the sacrum. Articulation. With the sacrum. Attachment of the Muscles. On either side the Coccygeus; behind, the Glutaeus maxi- mus; at its apex, the Sphincter ani; and in front, the Levator ani. Of the Spine in General.—The spinal column, formed by the junction of the verte- brae, is situated in the median line, at the pos- terior part of the trunk: its average length is about two feet two or three inches; the lumbar region contributing seven parts, the dorsal eleven, and the cervical five. Viewed in front, it presents two pyramids joined together at their bases, the upper one being formed by all the true vertebrae from the second cervical to the last lumbar; the lower one by the false vertebrae, the sacrum, and coccyx. Viewed somewhat more closely, the uppermost pyramid is seen to be formed of three smaller pyramids. Of these, the most superior one consists of the six lower cervical vertebrae, its apex being formed by the axis or second cervical, its base by the first dorsal. The second pyramid, which is inverted, is formed by the four upper dorsal vertebrae, the base being at the first dorsal, the smaller end at the fourth. The third pyramid commences at the fourth dorsal, and gradually increases in size to the fifth lumbar. Viewed laterally (Fig. 17), the spinal column presents several curves. In the dor- 4 Fig. 17.—Lateral View of Spine. 2d Cervical or Axis. 4-1 io~ /?Lumhar.. 18 OSTEOLOGY. sal region, the seat of the principal curvature, the spine is concave anteriorly; whilst in the cervical and lumbar regions it is convex anteriorly, especially in the latter. The spine has also a slight lateral curvature, the convexity of which is directed towards the right side. This is most probably produced, as Bichat first explained, from the effect of muscular action; most persons using the right arm in preference to the left, especially in making long-continued efforts, when the body is curved to the right side. In support of this explanation, it has been found by Beclard, that in one or two individuals who were left handed, the lateral curvature was directed to the left side. The spinal column presents for examination an anterior, a posterior, and two lateral surfaces, a base, summit, and vertebral canal. The anterior surface presents the bodies of the vertebrae separated in the fresh state by the intervertebral discs. The bodies are broad in the cervical region, narrow in the upper part of the dorsal, and broadest in the lumbar region. The whole of this surface is convex transversely, concave from above downwards in the dorsal region, and convex in the same direction in the cervical and lumbar regions. The posterior surface presents in the median line the spinous processes. These are short, horizontal, with bifid extremities in the cervical region. In the dorsal region, they are directed obliquely above, assume almost a vertical direction in the middle, and are horizontal, like the spines of the lumbar vertebrae, below. They are separated by considerable intervals in the loins, by narrower intervals in the neck, and are closely approximated in the middle of the dorsal region. On either side of the spinous processes, extending the whole length of the column, is the vetebral groove, formed by the laminae in the cervical and lumbar regions, where it is shallow, and by the lamina and transverse processes in the dorsal region, where it is deep and broad. In the recent state, these grooves lodge the deep muscles of the back. External to the vertebral grooves are the articular processes, and still more externally the transverse processes. In the dorsal region, these latter processes stand backwards, on a plane considerably posterior to thft same pro- cesses in the cervical and lumbar regions. The transverse processes in certain regions of the spine are formed of two different parts, or segments. In the cer- vical region, these two segments are distinct; the one arising from the side of the body, the other from the pedicle of the vertebra; and these uniting, inclose the vertebral foramen. In the dorsal region, the anterior segment is wanting; the pos- terior segment retaining the name of the transverse process. In the lumbar region, the anterior segments (which are largely developed) are called the transverse pro- cesses ; but, in reality, they are lumbar ribs, the posterior segments or true trans- verse processes existing in a rudimentary state, and being developed from the supe- rior articular processes, as in the cervical region. In the cervical region, the tranverse processes are placed in front of the articular processes, and between the intervertebral foramina. In the lumbar they are placed also in front of the arti- cular processes, but behind the intervertebral foramina. In the dorsal region, they are posterior both to the articular processes and foramina. The lateral surfaces are separated from the posterior by the articular processes in the cervical and lumbar regions, and by the tranverse processes in the dorsal. These surfaces present in front the sides of the bodies of the vertebrae, marked in the dorsal region by the facets for articulation with the heads of the ribs. More posteriorly are the intervertebral foramina, formed by the juxtaposition of the inter- vertebral notches, oval in shape, smallest in the cervical and upper part of the dorsal regions, and gradually increasing in size to the last lumbar. They are situated between the transverse processes in the neck, and in front of them in the back and loins, and transmit the spinal nerves. The base of the vertebral column is formed by the under surface of the body of the fifth lumbar vertebra, and the summit by the upper surface of the atlas. The vertebral canal follows the different curves of the spine; it is largest in those regions in which the spine enjoys the greatest free- dom of movement, as in the neck and loins, where it is wide and triangular; and narrow and rounded in the back, where motion is more limited. OCCIPITAL BONE. 19 THE SKULL. The Skull is divided into two parts, the Cranium and the Face. The Cranium is composed of eight bones; viz., the occipital, two parietal, frontal, two temporal, sphenoid, and ethmoid. The Face is composed of fourteen bones; viz., the two nasal, two superior maxillary, two lachrymal, two malar, two palate, two inferior turbinated, vomer, inferior maxillary. The ossicula auditus, the teeth, and Wor- mian bones, are not included in this enumeration. Cranium, 8 bones. Skull, 22 bones. Face, 14 bones. Occipital. Two Parietal. Frontal. Two Temporal. Sphenoid. Ethmoid. Two Nasal. Two Superior Maxillary. Two Lachrymal. Two Malar. Two Palate. Two Inferior Turbinated. Vomer. Inferior Maxillary. The Occipital Bone. The Occipital Bone (Fig. 18) is situated at the posterior and inferior part of the cranium, is trapezoid in form, curved upon itself, and presents for examination two surfaces, four borders, and four angles. Occipital Bone. Outer Surface, X rface >>? Oceip. Fr^^ Vrot?t7,_ .trot^^ nn**w rah X ''•-•••■•.•••.?o*-.. ^ Foramen Magnum ■ibere'lrs for C'Acel: Lief" 20 OSTEOLOGY. External Surface. Midway between the summit of the bone and the posterior margin of the foramen magnum is a prominent tubercle, the external occipital pro- tuberance, for the attachment of the ligamentum nuchae; and descending from it, as far as the foramen, a vertical ridge, the external occipital crest. Passing out- wards from the .occipital protuberance on each side are two semicircular ridges, the superior curved lines; and running parallel with these from the middle of the crest, are the tw7o inferior curved lines. The surface of the bone above the supe- rior curved lines presents on each side a smooth surface, which in the recent state, is covered by the occipito-frontalis muscle, whilst the ridges, as well as the surfaces of the bone between them, serve for the attachment of numerous muscles. The superior curved line gives attachment internally to the Trapezius, externally to the Occipito-frontalis, and Sterno-cleido-mastoideus; to the extent shown in the figure; the depressions between the curved lines to the Complexus internally, the Splenius capitis and Obliquus superior externally. The inferior curved line, and the depressions below it, afford insertion to the Rectus capitis posticus, major and minor. The foramen magnum is a large aperture, with rounded shelving margins, oblong in form, and wider behind than in front; it transmits the spinal cord and its mem- branes, the spinal accessory nerves, and the vertebral arteries. . On each side of the foramen magnum are the occipital condyles, for articulation with the Atlas; they are convex articular surfaces, oval in form, and directed dowTnwTards and out- wards ; they approach each other anteriorly, and encroach more upon the anterior than the posterior segment of the foramen. On their inner surface is a rough tubercle, for the attachment of the check ligaments; whilst external to them is a rough tubercular prominence, the transverse or jugular process, channelled in front by a deep notch, which forms part of the jugular foramen. The under surface of this process affords attachment to the Rectus capitis lateralis muscle; its upper or cerebral surface presents a deeply curved groove, which lodges part of the lateral sinus, whilst its prominent extremity is marked by a quadrilateral rough surface, covered with cartilage in the fresh state, and articulating with a similar surface on the petrous portion of the temporal bone. On the outer side of each condyle is a depression, the anterior condyloid fossa, perforated at the bottom by the anterior condyloid foramen. This foramen (sometimes double) is directed downwards, outwards, and forwards, and transmits the lingual nerve. Behind each condyle is seen an irregular fossa, also perforated at the bottom by a foramen, the posterior condyloid, for the transmission of a vein to the lateral sinus. This fossa and foramen are less regular in form and size than the anterior, and do not always exist. Sometimes they are found on one side only, and sometimes are altogether absent. In front of the foramen magnum is the basilar process, somewhat quadri- lateral in form, wider behind than in front; its under surface, which is rough, presenting in the median line a tubercular ridge, the pharyngeal spine, for the attachment of the tendinous raphe and Superior constrictor of the pharynx; and on each side of it, rough depressions for the attachment of the Recti capitis antici, major and minor. The Internal or Cerebral Surface (Fig. 19) is deeply concave. The occipital part is divided by a crucial ridge into four fossre. The two superior, the smaller, receive the posterior lobes of the cerebrum, and present eminences and depressions corresponding to their convolutions. The two inferior, which receive the lateral lobes of the cerebellum, are larger than the former, and comparatively smooth; both are marked by slight grooves for the lodgment of arteries. At the point of meeting of the four divisions of the crucial ridge is an eminence, the internal occipital protuberance, which rarely corresponds to that on the outer surface. From this eminence, the superior division of the crucial ridge, called sulcus longi- tudinalis, runs upwards to the superior angle of the bone; it presents a deep groove for the superior longitudinal sinus, whilst its margins give attachment to the falx cerebri. The inferior division, the internal occipital crest runs to the margin of the foramen magnum, on the edge of which it becomes gradually lost: OCCIPITAL BONE. 21 this ridge, which is bifurcated below, serves for the attachment of the falx cere- belli, and is slightly grooved for the lodgment of the occipital sinuses. The transverse grooves (sulci transversales) pass outwards to the lateral angles; they are deeply grooved, for the lodgment of the lateral sinuses, their prominent margins affording attachment to the tentorium cerebelli. At the point of meeting of these four grooves is a depression for the torcular Herophili, placed a little to the right of the internal occipital protuberance. In the centre of the basilar portion of the bone is the foramen magnum, and above its margin, but nearer its anterior than its posterior part, the internal openings of the anterior condyloid foramina; the internal openings of the posterior condyloid foramina being a little external and posterior to them, and protected above by a small arch of bone. In front of the foramen magnum is the basilar process, presenting a shallow longitudinal depres- sion, the basilar groove, for supporting the medulla oblongata; whilst on its lateral Fig. 19.—Occipital Bone. Inner Surface. Sie/ieriof Angle Inferior A naif V margins is observed a narrow channel on each side, which, when united with a similar channel on the petrous portion of the temporal bone, forms a groove, the inferior petrosal, which lodges the inferior petrosal sinus. Angles. The superior angle is acute, and is received into the interval between the posterior superior angles of the two parietal bones: it corresponds with that part of the head in the foetus which is called the posterior fontanelle. The infe- rior angle is represented by the square-shaped surface of the basilar process. At an early period of life, a layer of cartilage separates this part of the bone from the sphenoid; but in the adult, the union between them is osseous. The lateral 22 OSTEOLOGY. angles correspond to the outer ends of the transverse grooves, and are received into the interval between the posterior inferior angles of the parietal and the mastoid portion of the temporal. Borders. The superior extends on each side from the superior to the lateral angle, is deeply serrated for articulation with the parietal bone, and forms by this union the lambdoid suture. The inferior border extends from the lateral to the inferior angle; its upper half is rough, and articulates with the mastoid por- tion of the temporal, forming the masto-occipital suture: the inferior half articu- lates with the petrous portion of the temporal, forming the petro-occipital suture: these two portions are separated from one another by the jugular process. In front of this process is a notch, which, with a similar one on the petrous portion of the temporal, forms the foramen lacerum posterius. This notch is often subdi- vided into two parts by a small process of bone. Structure. The occipital bone consists of two compact laminae, called the outer and inner tables, having between them the diploic tissue; this bone is especially thick, at the ridges, protuberances, condyles, and basilar process; whilst at the bottom of the fossae it is thin, semi-transparent, and destitute of diploe. Development (Fig. 20). The occipital bone has seven centres of development: four for the posterior or occi- Fig. 20.—Development of Occipital Bone. By / centres a. I lirtA t/t.e Jj.pt eces separate. ly for occipital porlwn t for each condyloid portion bcvshbevr portion pital part, one for the basilar portion, and one for each con- dyloid portion. The four centres for the occipital portion are arranged in pairs above and below the occipital protuberance, and appear about the tenth week of foetal life; the inferior pair make their appearance first, and join; the superior pair be- come also united: these two segments now join together, and form a single piece. The condyloid portions then os- sify ; and, lastly, the basilar portion. At birth, the bone consists of these four parts, separate from one another, the posterior being fissured in the direction of the original segments. At about the fourth year, the occipital and the two condyloid pieces join: and at about the sixth year the bone consists of a single piece. At a later period, between the eighteenth and twenty-fifth years, the occipital and sphenoid become united, form- ing a single bone. Articulations. With six bones: two parietal, two temporal, sphenoid, and Atlas. Attachment of3Iuscles. To the superior curved line are attached the Occipito- frontalis, Trapezius, and Sterno-cleido-mastoid. To the space between the curved lines, the Complexus, Splenius, capitis, and Obliquus superior; to the inferior curved line, and the space between it and the foramen magnum, the Rectus posticus ma- jor and minor; tothe transverse process, the Rectus lateralis; and to the basilar process, the Recti antici majores and minores, the Superior Constrictor of the pharynx. The Parietal Bones. The Parietal Bones form the sides and roof of the skull; they are of an irre- gular quadrilateral form, and present for examination two surfaces, four borders. and four angles. Surfaces. The External Surface (Fig. 21) is convex, smooth, and presents about its centre an eminence, called the parietal eminence, which indicates the point where ossification commenced. Crossing the centre of the bone in an arched direction PARIETAL BONE. 23 is a curved ridge, the temporal ridge, for the attachment of the temporal fascia. Above this ridge, the surface of the bone is rough and porous, and covered by the aponeurosis of the Occipito-frontalis; below it the bone is smooth, and affords Fig. 21.—Left Parietal Bone. External Surface. attachment to the Temporal muscle. At the back part of the superior border is a small foramen, the parietal foramen, which transmits a vein to the superior longi- tudinal sinus. Its existence is not constant, and its position varies considerably. The Internal Surface (Fig. 22) is concave, presents numerous eminences and depressions for lodging the convolutions of the brain, and minute furrows for the ramifications of the meningeal arteries; these run upwards and backwards from deep grooves, which commence in the anterior inferior angle, and at the central and posterior part of the lower border of the bone. Along the upper margin is part of a shallow groove, which, when joined to the opposite parietal, forms a channel for the superior longitudinal sinus, the elevated edges of which afford attachment to the falx cerebri. Near the groove are seen several depressions ; they lodge the Pacchionian bodies. The internal opening of the parietal foramen is also seen Avhen that aperture exists. Borders. The superior, the longest, is dentated to articulate with its fellow of the opposite side, forming the saggital suture. The inferior is divided into three parts; of these, the anterior is thin and pointed, bevelled at the expense of the outer surface, and overlapped by the tip of the great wing of the sphenoid; the middle portion is arched, bevelled at the expense of the outer surface, and overlapped by the squamous portion of the temporal; the posterior portion being thick and serrated for articulation with the mastoid portion of the temporal. The anterior border, deeply serrated, is bevelled at the expense of the outer sur- face above, and of the inner below; it articulates with the frontal bone, forming 24 OSTEOLOGY. the coronal suture. The posterior border, deeply denticulated, articulates with the occipital, forming the lambdoid suture. Angles. The anterior superior, thin and pointed, corresponds with that portion of the skull which in the foetus is membranous, and is called the anterior fon- tanelle. The anterior inferior angle is thin and lengthened, being received in the interval between the great wing of the sphenoid and the frontal. Its inner surface is marked by a deep groove, sometimes a canal, for the middle meningeal Fig. 22.—Left Parietal Bone. Internal Surface. artery. The posterior superior angle corresponds with the junction of the sagittal and lambdoid sutures. In the foetus this part of the skull is membranous, and is called the posterior fontanelle. The posterior inferior articulates with the mas- toid portion of the temporal bone, and presents on its inner surface a broad shallow groove for the lateral sinus. Development. The parietal bone is developed by one centre, which corresponds with the parietal eminence, and makes its first appearance about the fifth or sixth week of foetal life. Articulations. With five bones: the opposite parietal, the occipital, frontal, temporal, and sphenoid. Attachment of 3Iuscles. To one only, the temporal. The Frontal Bone. This bone, which resembles a cockle-shell in form, consists of two portions,— a vertical or frontal portion, situated at the anterior part of the cranium, forming the forehead; and a horizontal or orbito-nasal portion, which enters into the formation of the roof of the orbits and nose. Vertical Portion. External Surface (Fig. 23). In the median line, traversing the bone from the upper to its lowrer part, is a slightly elevated ridge, and in young subjects a suture, which represents the point of union of its two lateral FRONTAL BONE. 25 halves: in the adult, this suture usually disappears. On either side of this ridge, a little below the centre of the bone, is a rounded eminence, the frontal eminence, which indicates the point where ossification commenced. The whole surface of the bone above this part is smooth, and covered by the aponeurosis of the Occipito- frontalis muscle. Below the frontal protuberance, and separated from it by a slight groove, is the superciliary ridge, a curved eminence, broad internally where it is continuous with the nasal eminence, less distinct externally as it arches outwards. Beneath the superciliary ridge is the supra-orbital arch, a curved and prominent margin, which forms the upper boundary of the orbit, and separates the vertical from the horizontal portion of the bone. At the inner third of this arch is a notch, sometimes converted into a foramen by a bony process or ligament, and Fig. 23.—Frontal Bone. Outer Surface. called the supra-orbital notch ox foramen. It transmits the supra-orbital artery, veins, and nerve. The supra-orbital arch terminates externally in the external angular process, and internally in the internal angular process. The external angular is a strong prominent process, which articulates with the malar: running upwards and backwards from it is a .sharp curved line, the temporal ridge, for the attachment of the temporal fascia; and beneath it a slight concavity, that forms part of the temporal fossa, and gives origin to the Temporal muscle. The internal angular processes are less marked than the external, and articulate with the lachrymal bones. Between the twTo is a rough, uneven interval, called the nasal notch, which articulates in the middle line with the nasal, and on either side with the nasal process of the superior maxillary bones. Vertical Portion. Internal Surface (Fig. 24). Along the middle line of this surface is a vertical groove, sulcus longitudinalis, the edges of which unite below to form a ridge, the frontal crest; the groove lodges the superior longitudinal sinus, whilst its edges afford attachment to the falx cerebri. The crest terminates below, at a small opening, the foramen coecum, which is generally completed 26 OSTEOLOGY. behind by the ethmoid; it lodges a process of the falx cerebri, and occasionally transmits a small vein from the nose to the superior longitudinal sinus. On either side of the groove, the bone is deeply concave, presenting eminences and depressions for the convolutions of the brain, and numerous small furrows for lodging the ramifications of the anterior meningeal arteries. Several small, irre- gular fossae are also seen on either side of the groove, for the reception of the Pacchionian bodies. Horizontal Portion. External Surface. This portion of the bone consists of two thin plates, which form the vault of the orbits, separated from one another by the ethmoidal notch. Each orbital vault consists of a smooth, concave, trian- gular plate of bone, marked at its anterior and external part (immediately beneath the external angular process) by a shallow depression, the lachrymal fossa, for lodging the lachrymal gland; and at its anterior and internal part, by a depres- sion, sometimes a tubercle, for the attachment of the fibrous pulley of the supe- rior oblique muscle. The ethmoidal notch separates the two orbital plates: it is Fig. 24.—Frontal Bone. Inner Surface. quadrilateral; and filled up, when the bones are united, by the cribriform plate of the ethmoid. The edges of this notch present several half-cells, which, when united with corresponding half-cells on the upper surface of the ethmoid, com- plete the ethmoidal cells: two grooves are also seen crossing these edo*es'trans- versely ; they are converted into canals by articulation with the ethmoid, and are called the anterior and posterior ethmoidal canals ; they open on the inner wall of the orbit. In front of the ethmoidal notch is the nasal spine, a sharp eminence, which projects downwards and forwards, and the grooved base of which forms part of the roof of the nose. It articulates in front with the crest of the nasal bones, behind with the perpendicular plate of the ethmoid. On either side of this spine are the openings of the frontal sinuses. There are two irregular cavities, TEMPORAL BONE. 27 which extend upwards and outwards, a variable distance, between the two tables of the skull, and are separated from one another by a thin bony septum. They give rise to the prominences above the root of the nose, called the nasal emi- nences. In the child they are absent, and they become gradually developed as age advances. They are lined with mucous membrane, arid communicate with the nose by the infundibulum. The Internal Surface of the Horizontal Portion presents the convex upper surfaces of the orbital plates, separated from each other in the middle line by the ethmoidal notch, and marked by eminences and depressions for the convolutions of the anterior lobes of the brain. Borders. The border of the vertical portion is thick, strongly serrated, bevelled at the expense of the internal table above, where it rests upon the parietal, at the expense of the external table at each side, where it receives the lateral pressure of those bones: this border is continued below, into a triangular rough surface, which articulates with the great wing of the sphenoid. The border of the hori- zontal portion is thin, bevelled at the expense of the internal table, and articu- lates with the lesser wing of the sphenoid. Structure. The vertical portion consists of diploic tissue, contained between two compact laminae, the bone being especially thick in the situation of the nasal emi- nences and external angular processes. The horizontal portion is thinner, more translucent, and composed entirely of compact tissue. Development. The frontal bone is developed by tivo centres, one for each lateral half, which make their appearance, at an early period of foetal life, in the situation of the orbital arches. At birth it consists of two pieces, which afterwards become united along the middle line, by a suture which runs from the vertex to the root of the nose. This suture becomes obliterated within a few years after birth; but it occasionally remains throughout life. Articulations. With twelve bones: two parietal, sphenoid, ethmoid; two nasal, two superior maxillary, twTo lachrymal, and two malar. Attachment of Muscles. To three pairs : the Corrugator supercilii, Orbicularis palpebrarum, and Temporal. The Temporal Bones. The Temporal bones, situated at the side and base of the skull, present for examination a squamous, mastoid, and petrous portion. The Squamous Portion (Fig. 25), the most anterior and superior part of the bone, is flattened and scale-like in form, thin and translucent in texture. Its outer surface is smooth, convex, and grooved for the deep temporal arteries; it affords attachment to the fibres of the Temporal muscle, and forms part of the tem- poral fossa. At its back part may be seen a curved ridge—part of the temporal ridge; it serves for the attachment of the temporal fascia, limits the origin of the Temporal muscle, and marks the boundary between the squamous and mastoid portions of the bone. Projecting from the lower part of the squamous portion, is a long and arched process of bone, the zygomatic process. It is at first directed outwards, its two surfaces looking upwards and downwards; it then appears as if twisted upon itself, and takes a direction forwards, its surfaces now looking inwards and outwards. The superior border of this process is long, thin, and sharp, and serves for the attachment of the temporal fascia. The inferior, short, thick, and arched, has attached to it some of the fibres of the Masseter muscle. Its outer surface is convex and subcutaneous. Its inner, concave, also affords attachment to the Masseter. The extremity, broad and deeply serrated, articulates with the malar bone. This process is connected to the temporal bone by three divisions, called the roots of the zygomatic process, an anterior, middle, and posterior. The anterior, which is short, but broad and strong, runs trans- versely inwards into a rounded eminence, the eminentia articularis. This eminence forms"the front boundary of the glenoid fossa, and in the recent state is covered with cartilage. The middle root runs obliquely inwards, and terminates at the 28 OSTEOLOGY. edge of a well-marked fissure, the Glaserian fissure; whilst the posterior, which is strongly marked, runs from the upper border of the zygoma, in an arched direction, upwards and backwards, forming the posterior part of the temporal ridge. At the junction of the anterior and middle roots is a projection, called the tubercle, for the attachment of the external lateral ligament of the lower jaw; and between these roots is a large oval depression, forming part of the glenoid fossa, for the reception of the condyle of the low.er jaw. This fossa is bounded in front by the eminentia articularis; behind, by the vaginal process; and exter- nally by the auditory process; and is divided into two parts by a narrow slit, the Glaserian fissure: the anterior part, formed by the squamous portion of the bone, is smooth, covered in the recent state with cartilage, and articulates with the condyle of the lower jaw; the posterior part, rough and uneven, and formed chiefly by the vaginal process of the petrous portion, lodges part of the parotid gland. The Glaserian fissure, dividing the two, leads into the tympanum; it Fig. 25.—Left Temporal Bone. Outer Surface. lodges the processus gracilis of the malleus, and transmits the laxator tympani muscle and the anterior tympanic artery. The chorda tympani nerve passes through a separate canal, parallel to the Glaserian fissure, on the outer side of the Eustachian tube, in the retiring angle between the squamous and petrous portions of the temporal bone. The internal surface of the squamous portion (Fig. 26) is concave, presents numerous eminences and depressions for the convolutions of the cerebrum, and two well-marked grooves for the branches of the middle meningeal artery. Borders. The superior border is thin, bevelled at the expense of the internal surface, so as to overlap the lower border of the parietal bone, forming the squa- mous suture. The anterior inferior border is thick, serrated, and bevelled alter- nately at the expense of the inner and outer surfaces, for articulation with the great wing of the sphenoid. TEMPORAL BONE. 29 The Mastoid Portion is situated at the posterior part of the bone; its outer surface is rough, and perforated by numerous foramina : one of these, of large size, situated at the posterior border of the bone, is termed the mastoid foramen; it transmits a vein to the lateral sinus and a small artery. The position and size of this foramen are very variable, being sometimes situated in the occipital bone, or in the suture between it and the occipital. The mastoid portion is continued below into a conical projection, the mastoid process, the size and form of which vary considerably in different individuals. This process serves for the attach- ment of the Sterno-mastoid, Splenius capitis, and Trachelo-mastoid (see Fig. 25); on the inner side of the mastoid process is a deep groove, the Digastric fossa, for the attachment of the Digastric muscle, and running parallel with it, but more internal, the occipital groove, which lodges the occipital artery. The internal surface presents a deeply curved groove, which lodges the lateral sinus, and into it may be seen opening the mastoid foramen. Fig. 26.—Left Temporal Bone. Inner Surface. Borders. The superior border of the mastoid portion is rough and serrated for articulation with the posterior inferior angle of the parietal bone. The posterior border, also uneven and serrated, articulates with the inferior border of the occi- pital bone between its lateral angle and jugular process. The Petrous Portion, so named from its extreme density and hardness, is a pyramidal process of bone, wedged in at the base of the skull between the sphenoid and occipital bones. Its direction from without is forwards, inwards, and a little downwards. It presents for examination a base, an apex, three surfaces, and three borders. The base is applied against the internal surface of the squamous and mastoid portions, its upper half being concealed, but its lower half is exposed by their divergence, which brings into view the oval expanded orifice of a canal leading into the tympanum, the meatus auditorious externus. This canal is situated between the mastoid process and the posterior and middle roots of the zygoma ; its upper margin is smooth and rounded, its lower surrounded by a curved plate of 30 OSTEOLOGY. bone, the auditory process, the free margin of which is rough, for the attachment of the cartilage of the ear. The apex of the petrous portion, rough and uneven, is received into the angular interval between the spinous process of the sphenoid and the basilar process of the occipital; it presents the anterior orifice of the carotid canal, and forms the posterior and external boundary of the foramen lacerum medium. The anterior surface (Fig. 26) of the petrous portion forms the posterior boundary of the middle fossa of the skull. This surface is continuous with the squamous portion, to which it is united by a suture, the temporal suture, the remains of which are distinct at a late period of life. Proceeding from the base to the apex, this surface presents five points for examination. 1. An eminence which indicates the situation of the superior semicircular canal. 2. A shallow groove, sometimes double, leading backwards to an oblique opening, the hiatus Fallopii, for the passage of the petrosal branch of the Vidian nerve. 3. A smaller opening immediately beneath and external to the latter for the passage of the smaller petrosal nerve. 4. Near the apex of the bone is seen the termination of the carotid canal, the wall of wdiich in this situation is deficient in front. 5. Above the foramen is a shallow depression for the reception of the Gasserian ganglion. The posterior surface forms the front boundary of the posterior fossa of the skull, and is continuous with the inner surface of the mastoid portion of the bone. It presents three points for examination. 1. About its centre is a large orifice, the meatus auditorious internus. This aperture varies considerably in size; its margins are smooth and rounded, and it leads into a short and oblique canal, which is directed outwards and forwards. It transmits the auditory and facial nerves and auditory artery. 2. Behind the meatus auditorius is a small slit, almost hidden by a thin plate of bone, and leading to a canal, the aquaeductus vestibuli; it transmits a small artery and vein, and lodges a process of the dura mater. 3. In the interval between these two openings, but above them, is an angular depression, which lodges a process of the dura mater, and transmits a small vein into the cancellous tissue of the bone. The inferior or basilar Surface (Fig. 27) is rough and irregular, and forms part of the base of the skull. Passing from the apex to the base, this surface presents eleven points for examination : 1. A rough surface, quadrilateral in form, which serves partly for the attachment of the Levator palati and Tensor tympani muscles. 2. The opening of the carotid canal, a large circular aperture, which ascends at, first vertically upwards, and then making a bend, runs horizontally forwards and inwards. It transmits the internal carotid artery, and the carotid plexus. 3. The aquaeductus cochleae, a small triangular opening, lying on the inner side of the latter, close to the posterior border of the bone; it transmits a vein from the cochlea, which joins the internal jugular. 4. Behind these openings is a depression, the jugular fossa, which varies in depth and size in different skulls; it lodges the internal jugular vein, and with a similar depression on the margin of the occipital bone, forms the foramen lacerum posterius. 5. A small foramen for the passage of Jacobson's nerve (the tympanic branch of the glossopharyngeal). This is seen on the ridge of bone dividing the carotid canal from the jugular fossa. 6. The canal for Arnold's nerve, seen on the inner wall of the jugular fossa. 7. Behind the jugular fossa is a smooth square-shaped facet, the jugular surface, which articulates with the jugular process of the occipital bone. 8. The vaginal process, a very broad sheath-like plate of bone, which extends from the carotid canal to the mastoid process; it divides behind into two laminae, receiving between them the 9th point for examination, the styloid process; a long sharp spine, about an inch in length, continuous with the vaginal process, between the laminae of which it is received, and directed downwards, forwards, and inwards. It affords attachment to three muscles, the Stylo-pharyngeus, Stylo-glossusand Stylo-hyoideus, and two ligaments, the stylo-hyoid and stylo-maxillary. 10. The stylo-mastoid foramen, a rather large orifice, placed between the styloid and mastoid processes; it is the termination of the aquaeductus Fallopii, and transmits the facial nerve and stylo-mastoid artery. 11. The auricular fissure, situated between the vaginal THE TEMPORAL BONE. 31 and mastoid processes, and transmitting the auricular branch of the pneumo- gastric nerve. Borders. The superior, the longest, is grooved for the superior petrosal sinus, and has attached to it the tentorium cerebelli: at its inner extremity is a semilunar notch, upon which reclines the fifth nerve. The posterior border is intermediate in length between the superior and the anterior. Its inner half is marked by a groove, which, when completed by its articulation with the occipital, forms the channel for the inferior petrosal sinus. Its outer half presents a deep excavation Fig. 27.—Petrous Portion. Inferior Surface. for the jugular fossa, which, with a similar notch on the occipital, forms the fora- men lacerum posterius. A projecting eminence of bone occasionally stands out from the centre of the notch, and divides the foramen into two parts. The ante- rior border is divided into two parts, an outer, joined to the squamous^ portion by a suture, the remains of which are distinct; an inner, free, articulating with the spinous process of the sphenoid. At the angle of junction of these two parts, are seen two canals, separated from one another by a thin plate of bone, the processes cochleariformis; they both lead into the tympanum, the upper one transmitting the Tensor tympani muscle, the lower one the Eustachian tube. Structure. The squamous portion is like that of the other cranial bones, the mastoid portion cellular, and the petrous portion dense and hard. Development (Fig. 28). The temporal bone is developed by four centres, exclusive of those for the internal ear and the ossicula, viz.,—one for the squamous portion including the zygoma, one for the petrous and mastoid parts, one for the styloid, and one for the auditory process (tympanic bone). The first traces of the develop- ment of this bone are found in the squamous portion, they appear about the time when osseous matter is deposited in the vertebrae; the auditory process succeeds 32 OSTEOLOGY. next; it consists of an elliptical portion of bone, forming about three-fourths of a circle, the deficiency being above; it is grooved along its concave surface for the attachment of the membrana tympani, Fig. 28, -Development of Temporal Bone. By four Centres. 1 for Syuamou, portion includuun Zyqemw,. 22? too I for Auditoru yrueess f fnr Petrous $» Miustutd portions t fcrr Styloict proc. and becomes united by its extremities to the squamous portion during the last months of intra-uterine life. The pe- trous and mastoid portions then become ossified, and lastly the styloid process, which remains separate a considerable period, and is occasionally never united to the rest of the bone. At birth the temporal bone, excluding the styloid process, is formed of three pieces, the squamous and zygomatic, the petrous and mastoid, and the auditory. The auditory process joins with the squa- mous at about the ninth month. The petrous and mastoid join with the squa- mous during the first year, and the sty- loid process becomes united between the second and third years. The sub- sequent changes in this bone are the extension outwards of the auditory process so as to form the meatus audi- torius, the glenoid fossa becomes deeper, and the mastoid part enlarges from the development of numerous cellular cavities in its interior. Articidations. With five bones, occipital, parietal, sphenoid, inferior maxillary, and malar. Attachment of Muscles. To the squamous portion, the Temporal; to the zygoma, the Masseter; to the mastoid portion, the Occipito-frontalis, Sterno-mastoid, Splenius capitis, Trachelo-mastoid, Digastricus and Retrahens aurem; to the styloid process, the Stylo-pharyngeus, Stylo-hyoideus, and Stylo-glossus; and to the petrous portion, the Levator palati, Tensor tympani, and Stapedius. The Sphenoid Bone. The Sphenoid (^v, a "wedge;" elSdc;, " like") is situated at the anterior part of the base of the skull, articulating with all the other cranial bones, which it binds firmly and solidly together. In its form it somewhat resembles a bat, with its wings extended; and is divided into a central portion or body, two greater and two lesser wings extending outwards on each side of the body; and two processes, the pterygoid processes, which project from it below. The Body presents for examination four surfaces—a superior, an inferior, an anterior, and a posterior. The superior surface (Fig. 29). From before, backwards, is seen a prominent spine, the ethmoidal spine, for articulation with the ethmoid; behind this a smooth surface, presenting in the median line a slight longitudinal eminence, with a depression on each side, for lodging the olfactory nerves. A narrow transverse groove, the optic groove, bounds the above-mentioned surface behind; it lodges the optic commissure, and terminates on either side in the optic foramen, for the pas- sage of the optic nerve and ophthalmic artery. Behind the optic groove is a small eminence, olive-like in shape, the olivary process; and still more posteriorly, a deep depression, the pituitary fossa, or sella Turcica, which lodges the pituitary body. This fossa is perforated by numerous foramina, for the transmission of nutrient vessels to the substance of the bone. It is bounded in front by two small eminences, one on either side, called the middle clinoid processes, and behind by a square-shaped plate of bone, terminating at each superior angle in a tubercle, the SPHENOID BONE. 33 posterior clinoid processes, the size and form of which vary considerably in different individuals. _ The sides of this plate of bone are notched below, for the passage of the sixth pair of nerves ; and behind, it presents a shallow depression, which slopes Fig. 29.—Sphenoid Bone. Superior Surface. obliquely backwards, and is continuous with the basilar groove of the occipital bone; it supports the medulla oblongata. On either side of the body may be seen a broad groove, curved somewhat like the Italic letter /; it lodges the internal Fig. 30.—Sphenoid Bone. Anterior Surface. carotid artery and the cavernous sinus, and is called the cavernous groove. The posterior surface, quadrilateral in form, articulates with the basilar process of the occipital bone. During childhood, a separation between these bones exists by means of a layer of cartilage; but in after-life this becomes ossified, and the two bones are immovably connected together. The anterior surface (Fig. 30) presents, in the middle line, a vertical lamella of bone, which articulates in front with the 5 34 OSTEOLOGY. perpendicular plate of the ethmoid. On either side of it are the irregular openings leading into the sphenoidal sinuses. These are two large, irregular cavities, hol- lowed out of the interior of the body of the sphenoid bone, and separated from one another by a more or less complete perpendicular septum; their form varies considerably, being often subdivided by irregular osseous laminae. These sinuses do not exist in children; but they increase in size as age advances. They are partially closed, in front and below, by two thin triangular plates of bone, the sphenoidal turbinated bones, leaving a round opening at their upper parts, by which they communicate with the upper and back part of the nose, and occa- sionally with the posterior ethmoidal cells. The lateral margins of this surface present a serrated edge, which articulates with the os planum of the ethmoid, com- pleting the posterior ethmoidal cells; the lower margin, also rough and serrated, articulates with the orbital process of the palate bone ; and the upper margin with the orbital plate of the frontal bone. The inferior surface presents, in the middle line, a triangular spine, the rostrum, which is continuous with the vertical plate on the anterior surface, and is received into a deep fissure between the alae of the vomer. On each side may be seen a projecting laminae of bone, which runs horizontally inwards from near the base of the pterygoid process: these plates, termed the vaginal processes, articulate with the edges of the vomer. Close to the root of the pterygoid process is a groove, formed into a complete canal when articu- lated with the sphenoidal process of the palate bone; it is called the pterygopala- tine canal, and transmits the pterygo-palatine vessels and pharyngeal nerve. The Greater Wings are two strong processes of bone, which arise at the sides of the body, and are curved in a direction upwards, outwards, and backwards; being prolonged behind into a sharp-pointed extremity, called the spinous process of the sphenoid. Each wing presents three surfaces and a circumference. The superior or cerebral surface forms part of the middle fossa of the skull; it is deeply concave, and presents eminences and depressions for the convolutions of the brain. At its anterior and internal part is seen a circular aperture, the foramen rotundum, for the transmission of the second division of the fifth nerve. Behind and external to this, a large oval foramen, the foramen ovale, for the trans- mission of the third division of the fifth, the small meningeal arterv, and the small petrosal nerve. At the inner side of the foramen ovale, a small aperture may occasionally be seen opposite the root of the pterygoid process ; it is the foramen Vesalii, transmitting a small vein. Lastly, in the apex of the spine of the sphe- noid is a short canal, sometimes double, the foramen spinosum; it transmits the middle meningeal artery. The external surface is convex, and divided by a trans- verse ridge, the pterygoid ridge, into two portions. The superior or larger, convex from above downwards, concave from before backwards, enters into the formation of the temporal fossa, and attaches part of the Temporal muscle. The inferior portion, smaller in size and concave, enters into the formation of the zygomatic fossa, and affords attachment to the External pterygoid muscle. It presents, at its posterior part, a sharp-pointed eminence of bone, the spinous process, to which is connected the internal lateral ligament of the lower jaw, and the Laxator tympani muscle. The pterygoid ridge, dividing the temporal and zygomatic portions, gives attachment to the upper origin of the External ptery- goid muscle. At its inner extremity is a long triangular spine of bone, which serves to increase the extent of origin of this muscle. The anterior or orbital surface, smooth and quadrilateral in form, assists in forming the outer wall of the orbit. It is bounded above by a serrated edge, for articulation with the frontal bone; below, by a rounded border, which enters into the formation of the spheno- maxillary fissure; internally, it enters into the formation of the sphenoidal fissure; whilst externally it presents a serrated margin, for articulation with the malar bone. At the upper part of the inner border is a notch, for the transmission of a branch of the ophthalmic artery; and at its lower part a small pointed spine of bone, which serves for the attachment of part of the lower head of the external rectus. One or two small foramina may occasionally be seen, for the passage of SPHENOID BONE 35 arteries; they are called the external orbiter foramina. Circumference: from the body of the sphenoid to the spine (commencing from behind), the outer half of this margin is serrated, for articulation with the petrous portion of the temporal bone; whilst the inner half forms the anterior boundary of the foramen lacerum medium, and presents the posterior aperture of the Vidian canal. In front of the spine, the circumference of the great wing presents a serrated edge, bevelled at the expense of the inner table below, and of the external above, which articulates with the squamous portion of the temporal bone. At the tip of the great wing a triangular portion is seen, bevelled at the expense of the internal surface, for articulation with the anterior inferior angle of the parietal bone. Internal to this is a broad serrated edge, for articulation with the frontal bone : this surface is con- tinuous internally with the sharp inner edge of the orbital plate, which assists in the formation of the sphenoidal fissure. The Lesser Wings (processes of Ingrassias) are two thin triangular plates of bone, which arise from the upper and anterior part of the body of the sphenoid; and projecting transversely outwards, terminate in a more or less acute point. The superior surface of each is smooth, flat, broader internally than externally, and supports the anterior lobe of the brain. The inferior surface forms the back part of the roof of the orbit, and the upper boundary of the sphenoidal fissure, or foramen lacerum anterius. This fissure is of a triangular form, and leads from the cavity of the cranium into the orbit; it is bounded internally by the body of the sphenoid; above, by the lesser wing; and below, by the orbital surface of the great wing; ■ and is converted into a foramen by the articulation of this bone with the frontal. It transmits the third, fourth, ophthalmic division of the fifth and sixth nerves, and the ophthalmic vein. The anterior border of the lesser wing is serrated, for articulation with the frontal bone; the posterior, smooth and rounded, is received into the fissure of Sylvius of the brain. The inner extremity of this border forms the anterior clinoid process. The lesser wing is connected to the side of the body by two roots, the upper thin and flat, the lower thicker, obliquely directed, and presenting on its outer side a small tubercle, for the attach- ment of the common tendon of the muscles of the eye. Between the two roots is the optic foramen, for the transmission of the optic nerve and ophthalmic artery. The Pterygoid processes (Fig. 31), one on each side, descend perpendicularly from the point where the body and great wing unite. Each pro- cess consists of an external and an internal plate, sepa- rated behind by an intervening notch ; but joined partially in front. The externedpterygoid plate is broad and thin, turned a little outwards, and forms part of the inner wall of the zygo- matic fossa. It gives attach- ment, by its outer surface, to the External pterygoid; its inner surface forms part of the pterygoid fossa, and gives attachment to the Internal pterygoid. _ The internal pterygoid plate is much narrower and longer, curving outwards at its extremity, into a hook-like process of bone, the hamular process, around which turns the tendon of the Tensor palati muscle. At the base of this plate is a small, oval, shallow depression, the scaphoid fossa, from which arises the Tensor palati, and above which is seen the posterior orifice of the Vidian canal. The outer surface of this plate forms part of the pterygoid fossa, the inner surface forming the outer boundary of the posterior aperture of the nares. The two pterygoid plates are Fig. 31.—Sphenoid Bone. Posterior Surface. 36 OSTEOLOGY. separated belowT by an angular notch, in which the pterygoid process, or tuberosity, of the palate bone is received. The anterior surface of the pterygoid process is very broad at its base, and supports Meckel's ganglion. It presents, above, the anterior orifice of the Vidian canal; and belowT, a rough margin, which articulates with the perpendicular plate of the palate bone. Development. The sphenoid bone is developed by ten centres, six for the pos- Fig. 32.—Development of Sphenoid. terior sphenoidal division, and four for By Ten Centres. the anterior sphenoid. The six centres ifretuiless'r-wing'uAnf-fnTtaflody for the post-sphenoid are, one for each greater wing and external pterygoid plate; one for each internal pterygoid plate; two for the posterior part of the body, The four for the anterior sphenoid are, one for each lesser wing and anterior part "lf^tacL iiUpterypUu of the body ; and one for each sphenoidal ifr™iy^at™;n3kexi.pter7jyT-ikfe turbinated bone. Ossification takes place in these pieces in the following order: the if„~* sphenoidal turbid ban. greater wing and external pterygoid plate are first formed, ossific granules being deposited close to the foramen rotundum on each side, at about the second month of foetal life; ossification spreading outwards into the great wing, and downwards into the external pterygoid process. Each internal pterygoid plate is then formed, and becomes united to the external about the middle of foetal life. The two centres for the posterior part of the body appear as separate nuclei, side by side, beneath the sella Turcica; they join about the middle of foetal life into a single piece, which remains ununited to the rest of the bone until after birth. Each lesser wing is formed by a separate centre, which appears on the outer side of the optic foramen, at about the third month; they become united and join with, the body at about the eighth month of foetal life. At about the end of the third year, ossification has made its appearance in the sphenoidal spongy bones. At birth, the sphenoid consists of three pieces ; viz., the greater wing and ptery- goid processes on each side; the lesser wings and body united. At the first year after birth, the greater wings and body are united. From the tenth to the twelfth year, the spongy bones commence their junction to the sphenoid, and become completely united by the twentieth year. Lastly, the sphenoid joins the occipital. Articulations. The sphenoid articulates with all the bones of the cranium and five of the face ; the two malar, two palate, and vomer : the exact extent of articu- lation with each bone is shown in the accompanying figures. Attachment of Muscles. The Temporal, External pterygoid, Internal pterygoid, Superior constrictor, Tensor palati, Laxator tympani, Levator palpebral, Obliquus superior, Superior rectus, Internal rectus, Inferior rectus, External rectus. For the exact attachment of the muscles of the eye to the sphenoid bone, see Fig. 133. The Sphenoidal Spongy Bones. The Sphenoidal Spongy Bones are two thin, curved plates of bone, which exist as separate pieces up to the fifteenth year. They are situated at the anterior and inferior part of the body of the sphenoid, serving to close in the sphenoidal sinuses in this situation. They are irregular in form, thick, and taperino* to a point behind, broader and thinner in front. Their inner surface, which°looks towards the cavity of the sinus, is concave; their outer surface convex. Each bone articulates in front with the ethmoid, an aperture of variable size bein°* left in their anterior wall which communicates with the posterior ethmoidal cells: behind, its point is placed under the vomer, and is received between the root of the pterygoid process on the outer side, and the rostrum of the sphenoid on the inner: externally, it articulates with the palate. ETHMOID BONE. 37 Outer Surface (enlarged). infiarb The Ethmoid. The Ethmoid (^0'j.os, " a sieve") is an exceedingly light spongy bone, of a cubical form, situated at the anterior part of the base of the cranium, between the two orbits at the root of the nose. It consists of three parts : a Fig 33 — Ethmoid Bone* horizontal plate, which forms part of the base of the cra- nium ; a perpendicular plate, which forms part of the sep- tum nasi; and twTo lateral masses of cells. The Horizontal or Cribri- form Plate (Fig. 33) forms part of the anterior fossa of the base of the skull, and is re- ceived into the ethmoid notch of the frontal bone between the two orbital plates. Pro- jecting upwards from the mid- dle line of this plate, at its fore part, is a thick smooth triangular process of bone, the crista galli, so called from its resemblance to a cock's-comb. Its base joins the cribriform plate. Its posterior border, long, thin, and slightly curved, serves for the attachment of the falx cerebri. Its anterior, short and thick, articulates with the frontal bone, and presents at its lowTer part two small projecting alge, which are received into corresponding depressions in the frontal, completing the foramen caecum behind. Its sides are smooth, and sometimes bulging, wdien it is found to inclose a small sinus. On each side of the crista galli, the cribriform plate is concave, to support the bulb of the olfactory nerves, and perforated by numerous foramina for the passage of its filaments. These foramina consist of three sets, corresponding to the three sets of olfactory nerves: an inner, which are lost in grooves on the upper part of the septum; an outer set, continued on to the surface of the upper spongy bones; whilst the middle set run simply through the bone, and transmit nerves distributed to the roof of the nose. At the front part of the cribriform plate, by the side of the crista galli, is a small fissure, which trans- mits the nasal branch of the ophthalmic nerve; and at its posterior part a trian- gular notch, which receives the ethmoidal spine of the sphenoid. The Perpendicular Fig. 34.—Perpendicular Plate of Ethmoid (enlarged). Shown by Plate (Fig. 34) is a thin removing the Right Lateral Mass. central lamella of bone, which descends from the under surface of the cribriform plate, and assists in forming the septum of the nose. Its anterior border articu- lates with the frontal spine and crest of the nasal bones. Its poste- rior, divided into two parts, is connected by its upper half with the rostrum of the sphenoid ; its lower half with the vomer. The inferior 38 OSTEOLOGY. border serves for the attachment of the triangular cartilage of the nose. On each side of the perpendicular plate numerous grooves and canals are seen, leading from the foramina on the cribriform plate; they lodge the filaments of the olfac- tory nerves. The Lettered Masses of the ethmoid are made up of a number of thin-walled cellular cavities, called the ethmoidal cells. In the disarticulated bone, many of these appear to be broken ; but when the bones are articulated, they are closed in in every part. The superior surface of each lateral mass presents a number of these apparently half-broken cellular spaces; these, however, are completely closed in when articulated with the edges of the ethmoidal fissure of the frontal bone. Crossing this surface are seen two grooves on each side, converted into canals by articulation with the frontal; they are the anterior and posterior ethmoidal fora- mina. They open on the inner wall of the orbit, and transmit,—the anterior, the anterior ethmoidal vessels and nasal nerve; the posterior, the posterior ethmoidal artery and vein. The posterior surface also presents large irregular cellular cavities, which are closed in by articulation with the sphenoidal turbinated bones, and orbital process of the palate. The cells at the anterior surface are completed by the lachrymal bone and nasal process of the superior maxillary, and those below also by the superior maxillary. On the outer surface of each lateral mass is a thin smooth square plate of bone, called the os planum; it forms part of the inner wall of the orbit, and articulates above with the frontal; below, with the superior maxillary and orbital process of the palate; in front, with the lachrymal; and behind, with the sphenoid. The cellular cavities of each lateral mass, thus Availed in by the os planum on the outer side, and by its articulation with the other bones already mentioned, are divided by a thin transverse bony partition into two sets, Avhich do not commu- nicate with each other ; they are termed the anterior and posterior ethmoidal cells; the former, the most numerous, communicate with the frontal sinuses above, and the middle meatus below, by means of a long flexuous cellular canal, the infundibulum ; the posterior, the smallest and least numerous, open into the supe- rior meatus, and communicate (occasionally) with the sphenoidal sinuses behind. If the inner Avail of each lateral mass is now examined, it will be seen howT these cellular cavities communicate Avith the nose. The internal surface of each lateral mass presents, at its upper and back part, a narrow horizontal fissure, the supe- rior meatus of the nose, bounded above by a thin curved plate of bone, the supe- rior turbinated bone of the ethmoid. By means of an orifice at the top part of this fissure, the posterior ethmoidal cells open into the nose. BcIoav the superior meatus is seen the convex surface of another thin convoluted plate of bone, the middle turbinated bone. It extends along the Avhole length of the inner Avail of each lateral mass ; its lower margin is free and thick, and its concavity, directed outAvards, assists in forming the middle meatus. It is by means of a large orifice at the upper and front part of this fissure, that the anterior ethmoid cells, and through them the frontal sinuses, by means of a funnel-shaped canal, the infundi- bulum, communicate Avith the nose. It Avill be remarked, that the Avhole of this surface is rough, and marked with numerous grooves and orifices, which run nearly vertically doAvmvards from the cribriform plate; they lodge the branches of the olfactory nerve, which are distributed on the mucous membrane covering this surface. From the inferior part of each lateral mass, immediately beneath the os planum, there projects doAvmvards and backAvards an irregular lamina of bone, called the unciform process, from its hook-like form : it serves to close in the upper part of the orifice of the antrum, and articulates Avith the inferior turbi- nated bone. Development. By three centres: one for the perpendicular lamella, and one for each lateral mass. The lateral masses are first developed, ossific granules making their first appear- ance in the os planum bctAveen the fourth and fifth months of fcetal life, and aftenvards in the spongy bones. At birth, the bone consists of the tAvo lateral WORMIAN BONES. 39 masses, which are small and ill-developed; but when the perpendicular and hori- zontal plates begin to ossify, as they do about the first year after birth, the lateral masses become joined to the cribriform plate. The formation and increase in the ethmoidal cells, which complete the formation of the bone, take place about the fifth or sixth year. Articulations. With fifteen bones: the sphenoid, two sphenoidal turbinated, the frontal, and eleven of the face—two nasal, tAvo superior maxillary, tAvo lachrymal, two palate, tAvo inferior turbinated, and vomer. The Wormian Bones. The Wormian* bones, called also, from their generally triangular form, ossa triquetra, are irregular plates of bone, presenting much variation in situation, number, and size. They are most commonly found in the course of the sutures, especially the lambdoid and sagittal, where they occasionally exist of large size; the superior angle of the occipital, and the anterior superior angle of the parietal, being occasionally replaced by large Wormian bones. They are not limited to the vertex, for they are occasionally found at the side of the skull, in the situation of the anterior inferior angle of the parietal bone, and in the squamous suture ; and more rarely they have been found at the base, in the suture between the sphenoid and ethmoid bones. Their size varies, in some cases not being larger than a pin's head, and confined entirely to the outer table; in other cases so large, that a pair of these bones formed the Avhole of that portion of the occipital bone above the superior curved lines, as described by Beclard and others. Their number is most generally limited to two or three; but more than a hundred have been found in the skull of an adult hydrocephalic skeleton. It appears most probable that they are separate accidental points of ossification, which, during their development and growth, remain separate from the adjoining bones. In their development, structure, and mode of articulation, they resemble the other cranial bones. Bones of the Face. The Facial Bones are fourteen in number, viz., the Two Palate, Tavo Nasal, Tavo Superior Maxillary, Tavo Lachrymal, Tavo Malar, Two Inferior Turbinated, Vomer, Inferior Maxillary. Fig. 35.—R ght Nasal Bone. will) Frontal B f, i 1 ' with —Opposite be>tiA i'lX ' Outer s urfaec. Fig. 36.—Right Nasal Bone. unth Fro lit cut Spdiu- Nasal Bones. The Nasal Bones (Figs. 35, 36), are tAvo small oblong bones, varying in size and form in different individuals ; they are placed side by side at the middle and upper part of the face, forming by their junction the bridge of the nose. Each bone presents for examina- tion tAvo surfaces, and four borders. The outer surface is concave from above doAvnwrards, con- vex from side to side, it is covered by the Compressor naris mus- cle, marked by nume- rous small arterial fur- rows, and perforated about its centre by a foramen, sometimes dou- ble, for the transmission of a small vein. Sometimes this foramen is absent on one or both sides, and occasionally the foramen ca?cum opens on this surface. The inner surface is * Wormius, a physician in Copenhagen. gr— -crest with Rrverieiic'ulex.r J'latc of Ethmoid. groove for iiaseil nerve Inner Surface 40 OSTEOLOGY. concave from side to side, convex from above doAvnwards ; in Avhieh direction it is traversed by a Avell-marked longitudinal groove, sometimes a canal, for the passage of a branch of the nasal nerve. The superior border is narroAv, thick, and serrated for articulation with the nasal notch of the frontal bone. The infe- rior border is broad, thin, sharp, directed obliquely downwards, outAvards, and backwards; serving for the attachment of the lateral cartilage of the nose. This border presents about its centre a notch, which transmits the branch of the nasal nerve above referred to, and is prolonged at its inner extremity into a sharp spine, which, when articulated with the opposite bone, forms the nasal angle. The external border is serrated, bevelled at the expense of the internal surface above, and of the external belowr, to articulate Avith the nasal process of the superior maxillary. The internal border, thicker above than below, articulates Avith its fellow of the opposite side, and is prolonged behind into a vertical crest, Avhich forms part of the septum of the nose : this crest articulates Avith the nasal spine of the frontal above, and the perpendicular plate of the ethmoid below. Development. By one centre for each bone, Avhich appears about the same period as in the vertebrae. Articulations. With four bones: tAvo of the cranium, the frontal, and ethmoid; and tAvo of the face, the opposite nasal and the superior maxillary. No muscles are directly attached to this bone. Superior Maxillary Bone. The Superior Maxillary is one of the most important bones of the face, in a surgical point of vieAV, on account of the number of diseases to Avhich some of its parts are liable. Its minute examination becomes, therefore, a matter of consi- derable importance. It is the largest bone of the face, excepting the loAver jaAv, and forms, by its union Avith its felloAV of the opposite side, the whole of the upper jaAv. Each bone assists in the formation of three cavities, the roof of the mouth, the floor and outer Avail of the nose, and the floor of the orbit; enters into the formation of tAvo fossa?, the zygomatic and spheno-maxillary, and two fissures, the spheno-maxillary, and pterygo-maxillary. Each bone presents for examination a body and four processes, malar, nasal, alveolar, and palatine. The body is someAvhat quadrilateral, and is hollowTed out in its interior to form a large cavity, the antrum of Highmore. It presents for examination four sur- faces : an external or facial, a posterior or zygomatic, a superior or orbital, and an internal. The externed or faded surface (Fig. 37), is directed forwards and outAvards. In the median line of the bone, just above the incisor teeth, is a depression, the incisive or myrtiform fossa, Avhich gives origin to the Depressor labii superioris alseque nasi. Above, and a little external to it, the Compressor naris arises. More external and immediately beneath the orbit, is another depression, the canine fossa, larger and deeper than the incisive fossa, from Avhich it is separated by a vertical ridge, the canine eminence, corresponding to the socket of the canine tooth. The canine fossa gives origin to the Levator anguli oris. Above the canine fossa is the infra- orbital foramen, the termination of the infra-orbital canal; it transmits the infra- orbital nerve and artery. Above the infra-orbital foramen is the margin of the orbit, Avhich affords partial attachment to the Levator labii superioris proprius muscle. The posterior or zygomatic surface is convex, directed backAvards and outwards, and forms part of the zygomatic fossa. It presents about its centre tAvo or three grooves leading to canals in the substance of the bone; they are termed the poste- rior dental canals, and transmit the posterior dental vessels and nerves. At the lower part of this surface is a rounded eminence, the maxillary tuberosity, especially prominent after the groAvth of the Avisdom-tooth, rough on its inner side for articulation Avith the tuberosity of the palate bone. At the upper and inner part of this surface is the commencement of a groove, Avhich, running down on the SUPERIOR MAXILLARY BONE. 41 nasal surface of the bone, is converted into a canal by articulation with the palate bone, forming the posterior palatine canal. The superior or orbital surface is thin, smooth, irregularlv quadrilateral, and forms part of the floor of the orbit. It is bounded internally by an irregular margin which articulates with three bones: in front, with the lachrymal: in the middle, with the os planum of the ethmoid; and behind, Avith the orbital process of the palate bone ; posteriorly, by a smooth rounded edge which enters into the formation of the spheno-maxillary fissure, and which sometimes articulates at its anterior extremity with the orbital plate of the sphenoid; bounded externally by Fig. 37.—Left Superior Maxillary Bone. Outer surface. Outer Surface. TENOo reuti '•?.•'./inc. ,' S- T 7 ,, , 7 '•'* / k.ilIf'"',*'M' '"WTO. Posterior J)t>7itat Cunali t»&J Maxillary Tuberosity, ■Bicuspids. the malar process, and in front by part of the circumference of the orbit; continuous, on the inner side, Avith the nasal, on the outer side, with the malar process. Along the middle line of this surface is a deep groove, the infra-orbital, for the passage of the infra-orbital nerve and artery. This groove commences at the middle of the posterior border of the bone, and passing fonvards, terminates in a canal Avhich subdivides into tAvo branches : one of the canals, the infra-orbital, opens just beloAv the margin of the orbit; the other, the smaller and most posterior one, runs in the substance of the anterior Avail of the antrum ; it is called the anterior dental, trans- mitting the anterior dental vessels and nerves to the front teeth of the upper jaw. The internal surface (Fig. 38) is unequally divided into two parts by a hori- zontal projection of bone, the palatine process ; that portion above the palate-pro- cess forms part of the outer wall of the nose ; the portion below it forms part of the cavity of the mouth. The superior division of this surface presents a large irregular-shaped opening leading into the antrum of Highmore. At the upper border of this aperture are a number of broken cellular cavities, which, in the articulated skull, are closed in by the ethmoid and lachrymal bones. Below the aperture, is a smooth concavity Avhich forms part of the inferior meatus of the nose, traversed by a fissure, the maxillary fissure, which runs from the loAver part of the orifice of the antrum obliquely doAvnwards and fonvards, and receiAres the maxillary process of the palate. Behind it, is a rough surface Avhich articulates Avith the perpendicular plate of the palate bone, traA'ersed by a groove which, commencing i-1 OSTEOLOGY. near the middle of the posterior border, runs obliquely downwards and fonvards, and forms, when completed by its articulation with the palate bone, the posterior palatine canal. In front of the opening in the antrum is a deep groove, converted into a canal by the lachrymal and inferior turbinated bones, and lodging the nasal duct. More anteriorly is a well-marked rough ridge, the inferior turbinated crest, for articulation with the inferior turbinated bone. The concavity above this ridge forms part of the middle meatus of the nose, whilst that below it forms part of the inferior meatus. The inferior division of this surface is concave, rough and uneven, and perforated by numerous small foramina for the passage of nutrient vessels. Fig. 38.—Left Superior Maxillary Bone. Inner Surface. Bo?ir.r partceo/li/ elosinij Or marhrd in ourL Ethmoid -Inferior Turbinated J?evla,te KSJJ17 Bristle passed Through Ant.palat. Canal The Antrum of High-more, or Maxillary Sinus, is a large triangular-shaped caA'ity, hollowed out of the body of the maxillary bone; its apex, directed out- Avards, is formed by the malar process; its base, by the outer wall of the nose. Its Avails are everyAvhere exceedingly thin, its roof being formed by the orbital plate, its floor by the alveolar process, bounded in front by the facial surface, and behind by the zygomatic. Its inner wall, or base, presents, in the disarticulated bone, a large irregular aperture, Avhich communicates Avith the nasal fossae. The margins of this aperture are thin and ragged, and the aperture itself is much con- tracted by its articulation Avith the ethmoid above, the inferior turbinated below, and the palate bone behind. In the articulated skull, this cavity communicates Avith the middle meatus of the nose generally by tAvo small apertures left between the above-mentioned bones. In the recent state, usually only one small opening exists, near the upper part of the cavity, sufficiently large to admit the end of a probe, the rest being filled in by the lining membrane of the sinus. Crossing the cavity of the antrum are often seen several projecting laminse of bone, similar to those seen in the sinuses of the cranium ; and on its outer Avail are the posterior dental canals, transmitting the posterior dental vessels and nerves to the teeth. Projecting into the floor are several conical processes, corresponding to the roots of the first and second molar teeth; in some cases, the floor is even per- forated by the teeth in this situation. It is from the extreme thinness of the walls of this cavity, that Ave are enabled to explain how tumors, growing from the SUPERIOR MAXILLARY BONES. 43 antrum, encroach upon the adjacent parts, pushing up the floor of the orbit and displacing the eyeball, projecting inward into the nose, protruding forwards on to the cheek, and making their Avay backwards into the zygomatic fossa, and doAvn- Avards into the mouth. The Malar Process is a rough, triangular eminence, situated at the angle of separation of the facial from the zygomatic surface. In front, it is concave, forming part of the facial surface ; behind, it is also concave, and forms part of the zygomatic fossa; superiorly., it is rough and serrated for articulation with the malar bone ; Avhilst below, a prominent ridge marks the division betAveen the facial and zygomatic surfaces. The Nasal Process is a thick triangular plate of bone, Avhich projects upAvards, inAvards, and backwards, by the side of the nose, forming its lateral boundary. Its external surface is concave, smooth, perforated by numerous foramina, and gives attachment to the Levator labii superioris alaeque nasi, the Orbicularis palpebrarum, and Tendo occuli. Its internal surface forms part of the inner walls of the nares ; it articulates above with the frontal, and presents a rough, uneven surface, A\hich articulates Avith the ethmoid bone, closing in the anterior ethmoid cells ; beloAv this is a transverse ridge, the superior turbinated crest, for articulation with the middle turbinated bone of the ethmoid, bounded below by a smooth concavity, which forms part of the middle meatus ; beloAv this is the inferior turbinated crest (already de- scribed), for articulation with the inferior turbinated bone ; and still more interiorly, the concavity which forms part of the inferior meatus. The anterior border of the nasal process is thin, and serrated for articulation with the nasal bone : its poste- rior border thick, and holloAved into a groove for the nasal duct; of the tAvo margins of this groove, the inner one articulates with the lachrymal bone, the outer one forming part of the circumference of the orbit. Just wdiere this border joins the orbital surface is a small tubercle, the lachrymal tubercle. This seiwes as a guide to the surgeon in the performance of the operation for fistula lachrymalis. The lachrymal groove in the articulated skull is converted into a canal by the lachrymal bone, and lachrymal process of the inferior turbinated ; it is directed doAvmvards, and a little backwards and outwards, is about the diameter of a goose-quill, slightly narroAver in the middle than at either extremity, and lodges the nasal duct. The Alveolar Process is the thickest part of the bone, broader behind than in front, and excavated into deep cavities for the reception of the teeth. These cavities are eight in number, and vary in size and depth according to the teeth they contain : those for the canine teeth being the deepest; those for the molars being Avidest, and subdivided into minor cavities ; those for the incisors being single, but deep and narrow. The Palate Process, thick and strong, projects horizontally inAvards from the inner surface of the bone. It is much thicker in front than behind, and forms the floor of the nares, and the roof of the mouth. Its upper surface is concave from side to side, smooth, and forms part of the floor of the nose. In front is seen the upper orifice of the anterior palatine (incisor) canal, Avhich leads into a fossa formed by the junction of the tAvo superior maxillary bones, and situated imme- diately behind the incisor teeth. It transmits the anterior palatine vessels, the naso-palatine nerves passing through the inter-maxillary suture. The inferior surface, also concave, is rough and uneven, and forms part of the roof of the mouth. This surface is perforated by numerous foramina for the passage of nutritious vessels, channelled at the back part of its alveolar border by a longi- tudinal groove, sometimes a canal, for the transmission of the posterior palatine vessels, and a large nerve, and presents little depressions for the lodgment of the pala- tine glands. This surface presents anteriorly the lower orifice of the anterior pala- tine fossa. The outer border is firmly united with the rest of the bone. The inner border is thicker in front than behind, raised above into a ridge, which^ with the corresponding ridge in the opposite bone, forms a groove for the reception of the vomer. The anterior margin is bounded by the thin concave border of the opening of the nose, prolonged forwards internally into a sharp process, forming, 44 . OSTEOLOGY. 1 for Nasal fy Sp.:""" 1'n.eial port™ r^-■^> ^ If : \i jpyW' 'J jf for Orbital fc %%-K^ V> ?* ' ........ (" Malar part''* *^H^-•^_^' ^-\ Anterior Surfaee. at Birth I fur In 1 for Palatalporf^ with a similar process of the opposite bone, the anterior nasal spine. The pos- terior border is serrated for articulation with the horizontal plate of the palate bone. Development (Fig. 39). This bone is formed at such an early period, and ossifi- cation proceeds in it Avith such rapidity, that it has been found impracticable hitherto to determine with, accu- Fig. 39.—Development of Superior Maxillary Bone. racy its number of Centres. It By Four Centres. appears, however, probable that /-\ it has four centres of develop- ment, viz., one for the nasal and facial portions, one for the orbital and malar, one for the incisive, and one for the palatal portion, in- cluding the entire palate except the incisive segment. The inci- sive portion is indicated in young bones by a fissure, which marks off a small segment of the palate, including the tAAO incisor teeth. In some animals, this remains permanently as a separate piece, constituting the inter-maxillary bone ; and in the human subject, where the jaAv is malformed, a detached piece is often found in this situation, most probably depending upon arrest of deve- lopment of this centre. The Interior Surfuoe. *-\i • . J J maxillary sinus appears at an earlier period than any of the other sinuses, its development commencing about the fourth month of foetal life. Articulations. With nine bones : tAvo of the cranium—the frontal and ethmoid, and Avith seven of the face, viz., the nasal, malar, lachrymal, inferior turbinated, palate, vomer, and its fellow of the opposite side. Sometimes it articulates with the orbital plate of the sphenoid. Attachment of Muscles. Orbicularis palpebrarum, Obliquus inferior oculi, Leva- tor labii superioris alneque nasi, Levator labii superioris proprius, Levator anguli oris, Compressor naris, Depressor alae nasi, Masseter, Buccinator. The Lachrymal Bones. The Lachrymal are the smallest and most fragile of all the bones of the face, situated at the front part of the inner Avail of the orbit, and resemble someAvhat in form, thinness, and size, a finger-nail; hence, they are termed the ossa unguis. Each bone presents for examination, tAvo surfaces and four borders. The external (Fig. 40) or orbital surface is divided by a vertical ridge into tAvo parts. The portion of bone in front of this ridge presents a smooth, concave, longitu- dinal groove, the free margin of Avhich unites with the nasal process of the superior maxillary bone, completing the lachrymal groove. The upper part of this groove lodges the lachrymal sac ; the lower part is continuous with the lachrymal canal, and lodges the nasal duct. The portion of bone be- hind the ridge is smooth, slightly concave, and forms part of the inner Avail of the orbit. The Fig. 40.—Left Lachrymal Bone. External Surface. \ W/4 Infer- (Sliejliiy ilaryet/ MALAR BONE. 45 ridge, and part of the orbital surface immediately behind it, afford attachment to the lensor tarsi: it terminates below in a small hook-like process, Avhich arti- culates with the lachrymal tubercle of the superior maxillary bohe, and completes the upper orifice of the lachrymal canal. It sometimes exists as a separate piece which is then called the lesser lachrymal bone. The internal or nasal surface presents a depressed furrow, corresponding to the elevated ridge on its outer surface. The surface of bone in front of this forms part of the middle meatus * and that behind it articulates with the ethmoid bone, filling in the anterior ethmoidal cells. Of the four borders, the anterior is the longest, and articulates with the nasal process of the superior maxillary bone. The posterior, thin and uneven, articulates with the os planum of the ethmoid. The superior border the shortest and thickest, articulates with the internal angular process of the frontal bone. Ihe inferior is divided by the lower edge of the vertical crest into two parts, the posterior articulating with the orbital plate of the superior maxillary bone; the anterior portion being prolonged downwards into a pointed process which articulates with the lachrymal process of the inferior turbinated bone' assisting in the formation of the lachrymal canal. Development. By a single centre, which makes its appearance soon after ossifi- cation of the vertebrae has commenced. Articulations. With four bones : two of the cranium, the frontal and ethmoid, and two of the face, the superior maxillary and the inferior turbinated. Attachment of Muscles. The Tensor tarsi. The Malar Bones. The Blalar are two small quadrangular bones, situated at the upper and outer part of the face, forming the prominence of the cheek, part of the outer Avail and floor of the orbit, and part of the tem- poral and zygomatic fossrc. Each Fig. 41.—Left-Malar Bone. Outer Surface. bone presents for examination an external and internal surface; four processes, the frontal, orbital, maxillary, and zygomatic; and four borders. The external sur- Bnarln paeiaed. through face (Fig. 41) is SinOOth, COnVeX, Tewporo-MaLa.rtini.ds perforated near its centre by one or tAvo small apertures, the malar canals, for the passage of small nerves and vessels, coA'ered by the Orbicularis palpebrarum mus- cle, and affords attachment to the Zygomaticus major and minor muscles. The internal surface (Fig. 42), directed backwards and inAvards, is concaAre, presenting internally a rough triangular surface, for articulation Avith the superior maxillary bone; and externally, a smooth concave surface, which forms the anterior boundary of the tem- poral fossa above, wider below, where it forms part of the zygomatic fossa. This surface presents a little above its centre the aperture of one or two malar canals, and affords attachment to part of two muscles, the temporal above, and the masseter below. Of the four processes, the frontal is thick and serrated, and articulates with the external angular process of the frontal bone. The orbital process is a thick and strong plate, which projects backwards from the orbital margin of the bone. Its upper surface, smooth and concave, forms, by its junction with the great ala of the sphenoid, the outer wall of the orbit. Its under surface, smooth and convex, forms part of the temporal fossa, Its anterior margin is smooth and rounded, forming part of the circumference of the orbit. Its superior margin, rough, and 46 OSTEOLOGY. directed horizontally, articulates with the frontal behind the external angular process. Its posterior margin is rough and serrated, for articulation Avith the sphenoid; internally it is also serrated for articulation with the orbital process of the superior maxillary. At the angle of junction of the sphenoid and maxillary portions, a short, rounded, non-articular margin is sometimes seen; this forms the anterior boundary of the spheno- Fig. 42.-Left Malar Bone. Inner Surface. maxillary fissure : occasionally, j£IfZ»* no such non-articular surface ex- ists, the fissure being completed by the direct junction of the maxillary and sphenoid bones, or by the interposition of a small Wormian bone in the angular in- terval between them. On the upper surface of the orbital process are seen the ori- fices of one or tAvo malar canals; one of these usually opens on the posterior surface, the other (occa- sionally two), on the facial sur- face : they transmit filaments of the orbital branch of the supe- rior maxillary nerve. The max- illary process is a rough trian- gular surface, Avhich articulates wTith the superior maxillary bone. The zygomatic process, long, narrow, and serrated, articulates Avith the zygomatic process of the temporal bone. Of the four borders, the superior, or orbital, is smooth, arched, and forms a considerable part of the circumference of the orbit. The inferior, or zygomatic, is continuous Avith the loAver border of the zygomatic arch, affording attachment by its rough edge to the Masseter muscle. The anterior or maxillary border is rough, and bevelled at the expense of its inner table, to articulate with the superior maxillary bone; affording attachment by its outer margin to the Levator labii superioris proprius, just at its point of junction Avith the superior maxillary. The posterior or temporal border, curved like an italic /, is continuous above Avith the commencement of the temporal ridge ; beloAv, Avith the upper border of the zygomatic arch; it affords attachment to the temporal fascia. Development. By a single centre of ossification, which appears at about the same period Avhen ossification of the vertebrae commences. Articulations. With four bones: three of the cranium, frontal, sphenoid, and temporal; and one of the face, the superior maxillary. Attachment of Muscles. Levator labii superioris proprius, Zygomaticus major and minor, Masseter, and Temporal. The Palate Bones. The Palate bones are situated at the posterior part of the nasal fossae, wedged in between the superior maxillary and the pterygoid process of the sphenoid. In form they are someAvhat like the letter L. Each bone assists in the formation of three cavities : the floor and outer Avail of the nose, the roof of the mouth, and the floor of the orbit; and enters into the formation of three fosste: the zygomatic, spheno- maxillary, and pterygoid. Each bone consists of tAvo portions: an inferior or horizontal plate, a superior or vertical plate. The Horizontal Plate is thick, of a quadrilateral form, and presents tAvo sur- faces and four borders. The superior surface, concave from side to side, forms the back part of the floor of the nares. The inferior surface, slightly concave and rough, forms the back part of the hard palate: At its posterior part may be seen a transverse ridge, more or less marked, for the attachment of the tendon of the Tensor palati muscle. At the outer extremity of this ridge is a deep groove, con- PALATE BONE. 47 verted into a canal by its articulation with the tuberosity of the superior maxil- lary bone, and forming the posterior palatine canal. Near this groove, the orifices of one or two small canals, accessory posterior palatine, may frequently be seen. The anterior border is serrated, bevelled at the expense of it's inferior surface, and articulates with the palate process of the superior maxillary bone. The posterior border is concave, free, and serves for the attachment of the soft palate. Its inner extremity is sharp and pointed, and when united with the opposite bone, forms a projecting process, the posterior nasal spine, for the attachment of the Azygos uvulae. The external border is united with the loAver part of the perpen- dicular plate almost at right angles. The internal border, the thickest, is serrated for articulation Avith its fellow of the opposite side; its superior edge is raised into a ridge, which, united with the opposite bone, forms a groove, in which the vomer is received. The Vertical Plate (Fig. 43) is thin, of an oblong form, and directed upwards and a little inAvards. It presents tAvo surfaces, an external and an internal, and four borders. The internal surface pre- sents at its lower part a broad shalloAV depression, Avhich forms part of the lateral boundary of the in- ferior meatus. Immediately above this is a well-marked horizontal ridge, the infe- rior turbinated crest, for the articulation of the in- ferior turbinated bone; above this, a second broad shalloAV depression may be seen, which .forms part of the lateral boundary of the middle meatus, surmounted above by a horizontal ridge, less prominent than the inferior, the superior turbinated crest, for the articulation of the middle tur- binated bone. Above the superior turbinated crest is a narroAV horizontal grooATe, which forms part of the superior meatus. The external surface is rough and irregular throughout the greater part of its extent, for articulation Avith the inner surface of the superior maxillary bone, its upper and back part being smooth Avhere it enters into the formation of the zygomatic fossa ; it is also smooth in front, Avhere it covers the orifice of the antrum. This surface presents toAvards its back part a deep groove, converted into a canal, the posterior palatine, by its articulation Avith the superior maxillary bones. It transmits the posterior pala- tine vessels and a large nerve. The anterior border is thin, irregular, and presents. opposite the inferior turbinated crest, a pointed projecting lamina, the maxillary process of the palate bone, Avhich is directed fonvards, and closes in the loAver and back part of the opening of the antrum, being received into a fissure that exists at the inferior part of this aperture. The posterior border (Fig. 44) presents a deep groove, the edges of Avhich are serrated for articulation Avith the ptery- goid process of the sphenoid. At the loAver part of this border is seen a pyramidal process of bone, the pterygoid process or tuberosity of the palate, Avhich is received into the angular interval betAveen the two pterygoid plates of the sphenoid at their inferior extremity. This process presents at its back part three grooAres, a median and tAvo lateral ones. The former is smooth, and forms part of the pterygoid fossa, affording attachment to the Internal pterygoid muscle; Fig. 43.—Left Palate Bone. Internal View (enlarged). [Cbl 2 Superior Mra SfAtw J'.ilo.tinr.Tiru, ^ MeuriHurtf Troeesi HORIZONTAL PLATE 48 OSTEOLOGY. Avhilst the lateral grooves are rough and uneven, for articulation Avith the anterior border of each pterygoid plate. The base of this process, continuous with the horizontal portion of the bone, presents the apertures of the accessory descending palatine canals; whilst its outer surface is rough, for articulation Avith the inner surface of the body of the superior maxillary bone. The superior border of the vertical plate presents tAvo well- Fig. 44.—Left Palate Bone. Posterior View (enlarged), marked processes, Separated by an intervening notch or foramen. The anterior, or larger, is called the orbital process ; the posterior, the sphenoidal. The Orbital Process, directed upAvards and outwards, is placed on a higher level than ,.«/,>,«..*•«.. tjie sphenoidal It presents five surfaces, which inclose a hollow ""V Sti/ienoieeeel hroccss. mi •. j • . 1 f^-f,. , L / cellular cavity, and is connected ..artuidurfton***-*"** to the perpendicular plate by a narroAv, constricted neck. Of these five surfaces, three are articular, two non-articular, or free surfaces. The three articu- lar are the anterior or maxillary surface, Avhich is directed for- /w\ wards, outAvards, and doAvmvards, is of an oblong form, and rough i«l ^IT* 'u%'latYm for articulation Avith the superior """'^j/ maxillary bone. The posterior or sphenoidal surface is directed backAvards, upwards, and inAvards. It ordinarily presents a small half-cellular cavity, which communicates with the sphenoidal sinus, and the margins of Avhich are serrated for articulation Avith the vertical part of the sphenoidal turbinated bone. The internal or ethmoidal surface is directed inAvards, upwards, and forwards, and articulates Avith the lateral mass of the ethmoid bone. In some cases, the cellular cavity aboA^e mentioned opens on this surface of the bone ; it then commu- nicates Avith the posterior ethmoidal cells. More rarely it opens on both surfaces, and then communicates Avith the posterior ethmoidal cells, and the sphenoidal sinus. The non-articular or free surfaces of the orbital process are the superior or orbital, directed upAvards and outAvards, of a triangular form, concave, smooth, articulating Avith the superior maxillary bone, and forming the back part of the floor of the orbit. The external or zygomatic surface, directed outAvards, back- wards, and doAvmvards, is of an oblong form, smooth, and forms part of the zygo- matic fossa. This surface is separated from the orbital by a smooth rounded border, which enters into the formation of the spheno-maxillary fissure. The Sphenoidal Process of the palate bone is a thin compressed plate, much smaller than the orbital, and directed upAvards and inAvards. It presents three surfaces and tAvo borders. The superior surface, the smallest of the three, articiK lates with the horizontal part of the sphenoidal turbinated bone; it presents a groove Avhich contributes to the formation of the pterygopalatine canal. The internal surface is concave, and forms part of the outer Avail of the nasal fossa. The external surface is divided into tAvo parts, an articular, and a non-articular portion; the non-articular portion is smooth and free, forming part of the zygo- matic fossa, whilst behind is a rough surface for articulation Avith the inner surface of the pterygoid process of the sphenoid. The anterior border forms the posterior boundary of the spheno-palatine foramen. The posterior border, serrated at the expense of the outer table, articulates with the internal surface of the pterygoid process.. The orbital and sphenoidal processes are separated from one another by a deep INFERIOR TURBINATED BONES. 49 -Right Inferior Turbinated Bone. Inner Surface. notch, Avhich is converted into a foramen, the spheno-palatine, by articulation Avith the sphenoidal turbinated bone. Sometimes the tAvo processes are united above, and form betAveen them a complete foramen, or the notch is crossed by one or more spicula of bone, so as to form tAvo or more foramina. In the articulated skull, this foramen opens into the back part of the outer Avail of the superior meatus, and transmits the spheno-palatine vessels and nerves. Development. From a single centre, Avhich makes its appearance at the angle of junction of the tAvo plates of the bone. From this point ossification spreads; in- Avards, to the horizontal plate; doAvmvards, into the tuberosity; and upAvards, into tie vertical plate. In the foetus, the horizontal plate is much longer than the vertical; and even after it is fully ossified, the Avhole bone is remarkable for its shortness. Articulations. AVith seven bones: the sphenoid, ethmoid, superior maxillary, inferior turbinated, vomer, opposite palate, and sphenoidal turbinated. Attachment of Muscles. The Tensor palati, Azygos uvulae, Internal and External pterygoid. The Inferior Turbinated Bones. The Inferior Turbinated bones are situated one on each side of the outer Avail of the nasal fossae. Each bone consists of a layer of thin "spongy" bone, curled upon itself like a scroll, hence its name "' turbinated ;" and extending horizontally across the outer Avail of the nasal fossa, immediately beloAv the orifice of the antrum. Each bone presents tAvo surfaces, two borders, and tAvo extremities. The internal surface (Fig. 45) is convex, perforated by numerous apertures, and traversed by longitudinal grooves and canals for the lodgment of Fig. 45.- arteries and veins. In the recent state it is covered by the lining membrane of the nose. The exter- nal surf ace is concave (Fig. 46), and forms part of the inferior meatus. Its upper border is thin, irregular, and connected to various bones along the outer Avail of the nose. It may be divided into three por- tions ; of these the anterior articu- lates Avith the inferior turbinated crest of the superior maxillary bone ; the posterior with the inferior turbinated crest of the palate bone; the middle portion of the superior border presents three well-marked processes, Avhich vary much Fig 46._Rjght inferior Turbinated Bone. in their size and form. Of these the Outer Surface. anterior and smallest is situated at the n r~, junction of the anterior fourth Avith the /^T-'/.. Jk>. ^-;ia ' posterior three-fourths of the bone; it is small and pointed, and it is called the la- ehrymedprocess, for it articulates Avith the anterior inferior angle of the lachrymal bone, and by its margins, with the groove on the back of the nasal process of the su- perior maxillary, and thus assists in forming the lachrymal canal. At the junction of the two middle fourths of the bone, but encroaching on the latter, a broad thin plate, the ethmoidal process, ascends to join the unciform process of the ethmoid; from the lower border of this process, a thin lamina of bone curves downwards and outwards, hooking over the lower edge of the orifice of the antrum, which it narroAvs below; it is called the maxillary process, and fixes the bone firmly on to the outer wall of the nasal fossa. The inferior border is free, thick and cellular in structure, more especially in the centre of the bone. Both extremities are more or less narrow and pointed. If the bone is held so that its outer concave 6 50 OSTEOLOGY. surface is.directed backAvards (i. e. tOAvards the holder), and its superior border, from which the lachrymal and ethmoidal processes project, upwards, the lachrymal process will be directed to the side to Avhich the bone belongs. Development. By a single centre, Avhich makes its appearance about the middle of fcetal life. Articulations. With four bones: one of the cranium, the ethmoid; and three of the face, the superior maxillary, lachrymal, and palate. No muscles are attached to this bone. eno/J ^edh Suj> -M** fl. I-0* The Yoaier. The Vomer (Fig. 47) is a single bone, situated vertically at the back part of the nasal fossae, and forming part of the septum of the nose. It is thin, someAvhat like a ploughshare in form, but it varies in different indiAucluals, being frequently bent to one or the other side; it Fig. 47. ^ omer. presents for examination two surfaces and four borders. The lateral surfaces are smooth, marked with small furroAvs for the lodgment of bloodvessels, and by a groove on each side, sometimes a canal, the naso- palatine, Avhich runs obliquely doAvmvards and forwards to the intermaxillary suture between the tAvo anterior palatine ca- nals ; it transmits the naso- palatine nerve. The superior border, the thickest, presents a deep groove, bounded on each side by a horizontal projecting ala of bone; the groove receives the rostrum of the sphenoid, Avhilst the alae are overlapped and retained by laminae Avhich project from the under surface of the body of the sphenoid at the base of the pterygoid processes. At the anterior part of the groove a fissure is left for the transmission of bloodvessels to the substance of the bone. The inferior border, the longest, is broad and uneven in front, where it articulates Avith the two superior maxillary 1 tones; thin and sharp behind, Avhere it joins with the palate bones. The upper half of the anterior border usually pre- sents two laminae of bone, AA'hich receive betAveen them the perpendicular plate of the ethmoid, the lower half consisting of a single rough edge, also occasionally channelled, Avhich is united to the triangular cartilage of the nose. The posterior border is free, concaAre, and separates the nasal fossae from one another behind. It is thick and bifid above, thin beloAv. Development. The vomer at an early period consists of tAvo laminae united below, but separated above by a very considerable interval. Ossification commences in it at about the same period as in the vertebrae. Articulation*. With six bones: tAvo of the cranium, the sphenoid, and ethmoid; and four of the face, the tAvo superior maxillary, the two palate bones, and with the cartilage of the septum. The vomer has no muscles attached to it. The Inferior Maxillary Boxe. The Inferior Maxillary Bone, the largest and strongest bone of the face, serves for the reception of the inferior teeth. It consists of a curved horizontal portion, the body, and of two perpendicular portions, the rami, Avhich join the former nearly at right angles behind. The Horizontal portion, or body (Fig. 48), is convex in its general outline, and INFERIOR MAXILLARY BONE. 51 curved somewhat like a horse-shoe. It presents for examination two surfaces and two borders Ihc External Surface is convex from side to side, concave from above downwards. In the median line is a well-marked vertical ridge, the sym- physis ; it extends from the upper to the lower border of the bone, and indicates Fig. 48.—Inferior Maxillary Bone. Outer Surface. Side View. ). By seven centres: one for the body, two for the coracoid process, tAvo for the acromion, one for the posterior border, and one for the inferior angle. That for the body makes its first appearance at about the same period that osseous matter is deposited in the vertebra?, and forms the chief part of the bone. At birth, all the other centres are cartilaginous. About the first year after birth, osseous deposition occurs in the middle of the coracoid process; Avhich usually becomes joined Avith the rest of the bone at the time Avhen the other centres make their appearance. Between the fifteenth and seventeenth years, osseous matter is deposited in the remaining centres in quick succession, and in the folloAving order: first, near the base of the acromion, and in the upper part of the coracoid process, the latter appearing in the form of a broad scale ; secondly, in the inferior angle and contiguous part of the posterior border ; thirdly, near the extremity of the acromion ; fourthly, in the posterior border. The acromion process, besides being formed of tAvo separate nuclei, has its base formed by an extension into it of the centre of ossification which belongs to the spine, the extent of Avhich varies in different cases. The tAvo separate nuclei unite, and then join with the extension carried in from the spine. These various epiphyses become united to the bone betAveen the ages of tA\enty-two and tAventy-five years. Articulations. With the humerus and clavicle. Attachment of 3Iuscles. To the anterior surface, the Subscapularis ; posterior surface, Supraspinatus, Infraspinatus ; spine, Trapezius, Deltoid ; superior border, Omo-hyoid; vertebral border, Serratus magnus, Levator anguli scapula, Rhom- boideus minor and major ; axillary border, Triceps, Teres minor, Teres major ; glenoid cavity, long head of the Biceps ; coracoid process, short head of Biceps, Coraco-brachialis, Pectoralis minor; and to the inferior angle occasionally a feAV fibres of the Latissimus dorsi. The Humerus. The Humerus is the longest and largest bone of the upper extremity; it pre- sents for examination a shaft and tAvo extremities. The Superior Extremity is the largest part of the bone ; it presents a rounded head, a constriction around the base of the head, the neck, and tAvo other emi- nences, the greater and lesser tuberosities (Fig. 77). The head, nearly hemispherical in form, is directed inAvards, upAvards, and a little backwards; its surface is smooth, coated with cartilage in the recent state, and articulates Avith the glenoid cavity of the scapula. The circumference of its articular surface is slightly constricted, and is termed the anatomical neck, in contradistinction to the constriction Avhich exists beloAv the tuberosities, and is called the surgical neck, from its being the seat of the accident called by surgeons, "fracture of the neck of the humerus." The neck, Avhich is obliquely directed, forming an obtuse angle with the shaft, is more distinctly marked in the lower half of its circumference, than in the upper half, Avhere it presents a narroAv groove, separating the head from the tuberosities. Its circumference affords attachment to the capsular ligament, and is perforated by numerous vascular foramina. The greater tuberosity is situated on the outer side of the head and lesser tuberosity. Its superior surface is rounded and marked by three flat facets, separated by two slight ridges, the most anterior giving attachment to the tendon of the Supraspinatus; the middle to the Infraspinatus; the posterior, to the Teres minor. The external surface of the great tuberosity is convex, rough, and continuous Avith the outer side of the shaft. The lesser tuberosity is more prominent, although smaller than the greater; it is situated in front of the head, and is directed inwards and forwards. Its OSTEOLOGY. Fig. -Left Humerus. Anterior View. Ctrmmtm. Orie/. <>f FLEXOR CARPI RADIALIS PALMARI8 LONCUS FLEXOR DICITORUM SU3L ,, CArtPI ULNARIS ATOP RADII LONCUS XTENSOR OASPI RADIALIJ LQNCIOR o^ Cenntiurn Oriqln ?--------of EXTENSOR.CARP. BAD. SREV „ DICITOmiM COMMUNIS ., MINIMI DICITI „ CARPI ULNARIS SUPINATOR BREVIS HUMERUS. 93 summit presents a prominent facet for the insertion of the tendon of the Subsca- pularis muscle. These two tuberosities are separated from one another by a deep groove, the bicipital groove, so called from its lodging the long tendon of the Biceps muscle. It commences above between the tAvo tuberosities, passes obliquely downwards and a little inAvards, and terminates at the junction of the upper Avith the middle third of the bone. It is deep and narrow at its commencement, and becomes shalloAV and a little broader as it descends. In the recent state it is covered Avith a thin layer of cartilage, lined by a prolongation of a synovial membrane of the shoulder joint, and receives part of the tendon of insertion of the Latissimus dorsi about its centre. The Shaft of the humerus is almost cylindrical in the upper half of its extent; prismatm and flattened below, it presents three borders and three surfaces for examination. The external border runs from the back part of the greater tuberosity to the external condyle, and separates the external from the posterior surface. It is rounded and indistinctly marked in its upper half, and serves for the attachment of the external head of the triceps muscle; its centre is traversed by a broad but shalloAV oblique depression, the musculo-spiral groove; its loAver part is marked by a prominent rough margin, a little curved from behind forwards, Avhich presents an anterior lip for the attachment of the Supinator longus above, the Extensor carpi radialis longior below, a posterior lip for the Triceps, and an interstice for the attachment of the external intermuscular aponeurosis. The internal border extends from the lesser tuberosity above to the internal condyle beloAv. Its upper third is marked by a prominent ridge, forming the inner lip of the bicipital groove, and giving attachment from above dowmvards to the tendons of the Latissimus dorsi, Teres major, and part of the origin of the inner head of the Triceps. About its centre is a rough ridge for the attachment of the Coraco-brachialis, and just beloAv this is seen the entrance of the nutritious canal directed doAvnwards. Its inferior third is raised into a slight ridge, Avhich becomes very prominent below; it presents an anterior lip for the attachment of the Brachialis anticus, a posterior lip for the internal head of the Triceps, and an intermediate space for the internal intermuscular aponeurosis. The anterior border runs from the front of the great tuberosity above, to the coronoid depression below, separating the internal from the external surface. Its upper part is very prominent and rough, forms the outer lip of the bicipital groove, and serves for the attachment of the tendon of the Pectoralis major. About its centre is seen the rough Deltoid impression; below, it is smooth and rounded, affording attachment for the Brachialis anticus. The external surf ace is directed outAvards above, where it is smooth, rounded, and covered by the Deltoid muscle; forAvards below, Avhere it is slightly concave from above downAvards, and gives origin to part of the Brachialis anticus muscle. About the middle of this surface, is seen a rough triangular impression for the insertion of the Deltoid muscle, and below it the musculo-spiral groove, directed obliquely from behind, forAvards and downwards ; it transmits the musculo-spiral nerve and superior profunda artery. The interned surface, less extensive than the external, is directed forwards above, inAvards and forAvards beloAv: at its upper part it is narroAv, and forms the bicipital groove. The middle part of this surface is slightly rough for the attachment of the Coraco-brachialis; its loAver part is smooth, concave, and gives attachment to the Brachialis anticus muscle. The posterior surface (Fig. 78) appears someAvhat tAvisted, so that its superior part is directed a little inwards, its inferior part backAvards and a little outAvards. Nearly the whole of this surface is covered by the external and internal heads of the Triceps, the former being attached to its upper and outer part, the latter to its inner and back part, their origin being separated by the musculo-spiral groove. The Lower Extremity is flattened from before backAvards, and curved slightly forwards; it terminates beloAv in a broad articular surface, Avhich is divided into 94 OSTEOLOGY. Fig. 78.—Left Humerus. Posterior Surface. tAvo parts by a shallow groove; on either side of the articular surface are the ex- ternal and internal condyles. The articular surface extends a little loAver than the con- dyles, and is curved slightly forwards, so as to occupy the more anterior part of the bone ; its greatest breadth is in the trans- verse diameter, and it is obliquely directed, so that its inner extremity occupies a lower level than the outer. The outer portion of this articular surface presents a smooth rounded eminence, Avhich has received the name of the lesser or radied head of the humerus ; it articulates with the cup-shaped depression on the head of the radius, is limited to the front and loAver part of the bone, and does not extend as far back as the other portion of the articular surface. On the inner side of this eminence is a shalloAV groove, in Avhich is received the inner margin of the cup-like cavity of the head of the radius. The inner or trochlear portion of the articular surface presents a deep depression between two well- marked borders. This surface is curved from before backwards, concave from side to side, and occupies the anterior lower and posterior part of the bone. The external border, less prominent than the internal, corresponds to the interval between the radius and ulna. The internal border-is thicker, more prominent, and, consequently, of greater length than the external. The grooved portion of the articular surface fits accurately Avithin the greater sigmoid cavity of the ulnar ; it is broader and deeper on the posterior than on the anterior aspect of the bone, and is directed obliquely from behind forwards, and from Avithout inwards. Immediately above the back part of the trochlear surface is a deep triangular de- pression, the olecranon depression, in which is received the summit of the olecranon process in extension of the forearm. Above the front part of the trochlear surface, is seen a smaller depression, the coronoid de- pression ; it receives the coronoid process of the ulna during flexion of the forearm. These fossae are separated from one another by a thin lamina of bone, Avhich is some- times perforated ; their margins afford at- tachment to the anterior and posterior ligaments of the elbow joint, and they are lined in the recent state by the synovial membrane of this articulation. Above the front part of the radial tuberosity, is seen a slight depression, which receh'es the HUMERUS. 95 ?9.—Plan of the Development of the Hu- merus. By seven Centres. Epiphyses if Head & Tuberosities hlrrul at S.y?a7irl unite hittA Shaft at ZO^p anterior border of the head of the radius when the forearm is strongly flexed. The external condyle is a small tubercular eminence, less prominent than the internal, curved a little forAvards, and giving attachment to the external lateral ligament of the elbow joint, and to a tendon common to the origin of some of the extensor and supinator muscles. The internal condyle, larger and more promi- nent than the external, is directed a little backwards; it gives attachment to the internal lateral ligament, and to a tendon common to the origin of some of the flexor muscles of the forearm. These eminences are directly continuous above with the external and internal borders. Structure. The extremities consist of cancellous tissue, covered Avith a thin compact layer ; the shaft is composed of a cylinder of compact tissue, thicker at the centre than at the extremities, and holloAved out by a large medullary canal. Development. By seven centres (Fig. 79); one for the shaft, one for the head, one for the greater tu- berosity, one for the radial, and one for the trochlear portion of the articular surface, and one for each condyle. The centre for the shaft ap- pears very early, soon after ossifica- tion has commenced in the clavicle, and soon extends towards the extremi- ties. At birth, it is ossified nearly in its whole length, the extremities re- maining cartilaginous. Between the first and second years,ossification com- mences in the head of the bone, and between the second and third years the centre for the tuberosities marks its appearance usually by a single ossific point, but sometimes, according to Bdclard, by one for each tuberosity, that for the lesser being small, and not appearing until after the fourth year. By the fifth year, the centres for the head and tuberosities have enlarged and become joined, so as to form a single large epiphysis. The lower end of the humerus is developed in the folloAving manner : At the end of the second year, ossifi- cation commences in the radial portion of the articular surface, and from this point extends inwards, so as to form the chief part of the articular end of the bone, the centre for the inner part of the articular surface not appearing until about the age of twelve. Ossification commences in the internal condyle about the fifth year, and in the external one not until about the age of thirteen or fourteen. About sixteen or seventeen years, the outer condyle and both portions of the articulating surface (having already joined) unite Avith the shaft; at eighteen years, the inner condyle becomes joined, Avhilst the upper epiphysis, although the first formed, is not joined until about the twentieth year. Articulations. With the glenoid cavity of the scapula, and with the ulna and radius. Attachment of Muscles. To the greater tuberosity, the Supraspinatus, Infra- spinatus, and Teres minor ; to the lesser tuberosity, the Subscapularis ; to the ante- rior bicipital ridge, the Pectoralis major ; to the posterior bicipital ridge and groove. the Latissimus dorsi and Teres major; to the shaft, the Deltoid, Coraco-brachialis. Brachialis anticus, External and Internal heads of the Triceps: to the internal Viiites wrtlt Shaft at 9(5 OSTEOLOGY. Fig. 80.—Bones of the Left Forearm. Anterior Surface. ULNA c r ei RADIUS fS.'-'xoR DIGITORUM SUBLIMIS PRON ATOR RADII. TERES etcceuriemaZ origin of FLEXOR LONCUS POLLICIS Radial Oric/irv FLEXOR DIGITORUM EUBLI M 18 Styloid I'rocess ^ SUPINATOR LONCUS Gvove Jor EXT. OSSIS METACAKPI POLLICI"! ,/*i«EXT.t>RIMI NTERNODII POLLICIS Styloi 75 ULNA. 97 condyle, the Pronator radii teres, and common tendon of the Flexor carpi radialis. Palmaris longus, Flexor digitorum sublimis, and Flexor carpi ulnaris; to the external condyloid ridge, the Supinator longus, and Extensor carpi radialis longior; to the external condyle, the common tendon of the Extensor carpi radialis brevior, Extensor communis digitorium, Extensor minimi digiti, and Ex- tensor carpi ulnaris, the Anconeus, and Supinator brevis. The Forearm is that portion of the upper extremity, situated between the elbow and Avrist. It is composed of tAvo bones, the Ulna and Radius. The Ulna. The Ulna (Fig. 80, 81) is a long bone, prismatic in form, placed at the inner side of the forearm, parallel Avith the radius, being the largest and longest of the two. Its upper extremity, of great thickness and strength, forms a large part of the articulation of the elbow joint; it gradually tapers as it descends, its inferior extremity being very small, and excluded from the Avrist joint by the interposi- tion of an interarticular fibro-cartilage. It is divisible into a shaft and two extremities. The Upper Extremity, the strongest part of the bone, presents for examination tAvo large curved processes, the Olecranon process and the Corynoid process, and tAvo concave articular cavities, the greater and leseer Sigmoid cavities. The Olecranon Process is a large thick curved eminence, situated at the upper and back part of the ulna. It rises someAvhat higher than the coronoid, is contracted where it joins the shaft, and curved forwards at the summit so as to present a prominent tip. Its posterior surface, directed backwards, is of a triangular form, smooth, subcutaneous, and covered by a bursa. Its superior surface, directed upwards, is of a quadrilateral form, marked behind by a rough surface for the attachment of the Triceps muscle, and in front, near the margin, by a slight transverse groove for the attachment of part of the posterior ligament of the elboAv joint. Its anterior surface is smooth, concave, covered with car- tilage in the recent state, and forms the upper and back part of the great sigmoid cavity. The lateral borders present a continuation of the same groove that was seen on the margin of the superior surface; they serve for the attachment of ligaments, \'\z., the back part of the internal lateral ligament internally; the posterior ligament externally. The olecranon process, in its structure as Avell as in its position and use, resembles the patella in the lower limb, and, like it some- times exists as a separate piece, not united to the rest of the bone. The Coronoid Process (foptovr), " a crow's beak;" ecSo?, " form") is a rough triangular eminence of bone Avhich projects horizontally forwards from the upper and front part of the ulna, forming the loAver part of the great sigmoid cavity. Its base is continuous with the shaft. Its apex, pointed, slightly curved upwards, is received into the coronoid depression of the humerus in flexion of the forearm. Its superior surface is smooth, concave, and forms the lower part of the great sigmoid cavity. The inferior surface is concave, directed downwards and forAvards, and marked internally by a rough impression for the insertion of the Brachialis anticus. At the junction of this surface Avith the body, is a rough eminence, the tubercle of the ulna, for the attachment of the oblique ligament. Its outer surface presents a narrow, oblong, articular depression, the lesser sigmoid cavity. The inner surface, by its prominent free margin, serves for the attachment of the front part of the internal lateral ligament. At the front part of this surface is a small rounded eminence for *the attachment of one head of the Flexor digitorum sublimis. Behind the eminence, a depression for part of the origin of the Flexor profundus digitorum, and descending from it a ridge, lost below on the inner border of the shaft, which gives attachment to one head of the Pronator radii teres. The Greater Sigmoid Cavity (ercr/J-a, etdoz, "form"), so called froin its resemblance to the Greek letter 2', is a semilunar depression of large size, situated betAveen the olecranon and coronoid processes, and serving for articulation Avith the trochlear surface of the humerus. About the middle of either lateral border of this cavity 9 98 OSTEOLOGY. is a notch, which contracts it someAvhat, and serves to indicate the junction of the two processes of Avhich it is formed. The cavity is concave from above downwards, and divided into tAvo lateral parts by a smooth elevated ridge, Avhich runs from the summit of the olecranon to the tip of the coronoid process. Of these tAvo portions, the internal is the largest, and slightly concave transversely; the external the smallest, being nearly plane from side to side. The Lesser Sigmoid Cavity is a narrow, oblong, articular depression, placed on the outer side of the coronoid process, and serving for articulation with the head of the radius. It is concave from before backAvards; and its extremities, which are prominent, serve for the attachment of the orbicular ligament. The Shaft is prismatic in form at'its upper part, and curved from behind forwards, and from within outAvards, so as to be convex behind and externally; its central part is quite straight; its loAver part rounded, smooth, and bent a little outwards; it tapers gradually from above dowmvards, and presents for examination three borders and three surfaces. The anterior border commences above at the prominent inner angle of the coro- noid process, and terminates below in front of the styloid process. It is well marked above, smooth and rounded in the middle of its extent, and affords attach- ment to the Flexor profundus digitorum, sharp and prominent in its loAver fourth for the attachment of the Pronator quadratus. It separates the anterior from the internal surface. The posterior border commences above at the apex of the triangular surface at the back part of the olecranon, and terminates beloAv at the back part of the sty- loid process; it is Avell marked in the upper three-fourths, and gives attachment to an aponeurosis common to the Flexor carpi ulnaris, the Extensor carpi ulnaris, and the Flexor profundus digitorum muscles; its lowrer fourth is smooth and rounded. This border separates the internal from the posterior surface. The external border commences above by tAvo lines, which converge one from each extremity of the lesser sigmoid cavity, inclosing betAveen them a triangular space for the attachment of part of the Supinator brevis, and terminates below at the midde of the articular surface for the radius. Its tAvo middle fourths are very prominent, and serve for the attachment of the interosseous membrane; its loAver fourth is smooth and rounded. This border separates the anterior from the posterior surface. The anterior surface, much broader above than beloAv, is concave in the upper three-fourths of its extent, and affords attachment to the Flexor profundus digito- rum; its loAver fourth, also concave, to the Pronator quadratus. The lower fourth is separated from the remaining portion of the bone by a prominent ridge, directed obliquely from above dowmvards and inAvards; this ridge marks the extent of attachment of the Pronator above. At the junction of the upper Avith the middle third of the bone is the nutritious canal, directed obliquely upwards and inwards. The posterior surface, directed backAvards and outwards, is broad and concave above, somewhat narroAver and convex in the middle of its course, narrow, smooth, and rounded beloAv. It presents above an oblique ridge, Avhicli runs from the pos- terior extremity of the lesser sigmoid cavity, doAvnwards to the posterior border, marking off a small triangular surface above it for the insertion of the Anconeus muscle, whilst the ridge itself affords attachment to the Supinator brevis. The surface of bone beloAv this is subdivided by a longitudinal ridge into tAvo parts, the internal part is smooth, concave, and gives origin (occasionally is merely covered by) the Extensor carpi ulnaris. The external portion, Avider and rougher, gives attachment from above dowmvards to part of the Supinator brevis, the Extensor ossis metacarpi pollicis, Extensor secundi internodii pollicis, and Extensor indicia muscles. The interned surface is broad and concave above, narroAv and convex below. It gives attachment by its upper three-fourths to the Flexor profundus digitorum muscle; is loAver fourth is subcutaneous. The Lower Extremity of the ulna is of small size, and excluded from the articu** lation of the Avrist joint. It presents for examination tAvo eminences; the outer ULNA. 99 Fig. 81.—Bones of the Left Forearm. Posterior surface. ULNA for EXT. CARPI RAD.LCNC. CXT.CARPI RAO.BREVIon EXT. CECUM3I i.vT—rJc c: 1 PCLU -rLcxon oiaiTor.'vii SUBLIMIS CARPI ULNAR. I CI s ITORUM COM MUNI; ;XT, MINIMI DICITI 100 OSTEOLOGY. and larger is a rounded articular eminence, termed the head of the ulna. The inner, narrower and more projecting, is a non-articular eminence, the styloid process. The head presents an articular facet, part of which, of an oval form, is directed downwards, and plays on the surface of the triangular fibro-cartilage, which separates this bone from the wrist joint; the remaining portion, directed outAvards, is narroAv, convex, and received into the sigmoid cavity of the radius. The styloid process projects from the inner and back part of the bone, and descends a little lower than the head, terminating in a rounded summit, which affords attach- ment to the internal lateral ligament of the Avrist The head is separated from the styloid process beloAv and in front, by a depression for the attachment of the triangular interarticular fibro-cartilage; "behind, by a shallow groove for the pas- sage of the tendon of the Extensor carpi ulnaris. Structure. Similar to that of the other long bones. Development. By three centres: one for the shaft, one for the inferior extremity and one for the olecranon (Fig. 82). The centre for the shaft appears a short time after the radius, and soon extends through the greater part of the bone. At birth, the ends are cartilaginous. About the fourth year a separate osseous nucleus appears in the middle of the head, Avhich soon Fig. 82 -Plan of the Development of the Ulna By Three Centres. Appea rs i;t fOi'1 yl— extends into the styloid process. About the tenth year, ossific matter Qlcera/ivn ^ appears in the upper cartilaginous end chief part of the olecranon being formed from an extension of the shaft of the bone into it. At about the sixteenth year, the upper epiphysis becomes joined, and at about the twen- tieth, the inferior one. Articulations. With the humerus and radius. Attachment of Muscles. To the olecranon: the Triceps, Anconeus, and one head of the Flexor carpi ulnaris. To the coronoid process: the Bra- chialis anticus, Pronator radii teres, Flexor sublimis digitorum, and Flexor profundus digitorum. To the shaft: the Flexor profundus digitorum, Pro- nator quadratus, Flexor carpi ulnaris, Extensor carpi ulnaris, Anconeus, zoth ,.* Supinator brevis, Extensor ossis meta- carpi pollicis, Extensor secundi inter- nodii pollicis, and extensor indicis. The Kaoius. The Jiadius is situated on the outer side of the forearm, lying parallel with the ulna, Avhich exceeds it in length and size. Its upper end is small and forms only a small part of the elboAv joint; but its loAver end is large, and forms the chief part of the Avrist. It is one of the long bones, having a prismatic form, slightly curved longitudinally, and presenting for examination a shaft and tAvo extremities. The Upper Extremity presents a head, neck, and tuberosity. The head is of a cylindrical form, depressed on its upper surface into a shalloAV cup, which receives the radial or lesser head of the humerus. Around the circumference of the head is a smooth articular surface, coated with cartilage in the recent state, broad internally Avhere it articulates Avith the lesser sigmoid cavity of the ulna, narrow in the rest of its circumference, to play in the orbicular liga- ment. The head is supported on a round, smooth, and constricted portion of bone, called the neck, which presents, behind, a slight ridge, for the attachment Appears at 4 '* pc«raat5tJ'ye--(^f''^-u-wt<*,«/i,.rAu*:<,i»,.c digitorum, and that of the Extensor p«l.,,tj indicis; the tendon of the Extensor minimi digiti passing through the groove at its point of articulation with the ulna. Development (Fig. 83). By three centres ; one for the shaft, and one for each extremity. That for the shaft makes its appearance near the centre of the bone, soon after the develop- ment of the humerus commences. At birth the shaft is ossified; but the ends of the bone are cartilaginous. About the end of the second year, ossification commences in the lower epiphysis ; and about the fifth year, in the upper one. At the age of puberty, the upper epiphysis becomes joined to the shaft; the lower epiphysis becom- Appcar, „t j \. n„-v, «* u s. The Metacarpal Bones are five in number : they arc long cylindrical bones, presenting for examination a shaft and tAvo extremities. 108 OSTEOLOGY. Common Characters of the Metacarpal Boxes. The shaft is prismoid in form, and curved longitudinally, so as to be convex in the longitudinal direction behind, concave in front. It presents three surfaces; tAvo lateral and one posterior. The lateral surfaces are concave, for the attach- ment of the Interossei muscles, and separated from one another by a prominent line. The posterior or dorsal surface is triangular, smooth, and flattened below, and covered, in the recent state, by the tendons of the Extensor muscles. In its upper half, it is divided by a ridge into two narrow lateral depressions, for the attachment of the Dorsal interossei muscles. This ridge bifurcates a little above the centre of the bone, and its branches run to the small tubercles on each side of the digital extremity. The carpal extremity, or base, is of a cuboidal form, and broader behind than in front: it articulates, above, witli the carpus ; and on each side, Avith the adjoin- ing metacarpal bones ; its dorsal a.nd palmar surfaces being rough, for the attach- ment of tendons and ligaments. The digital extremity, or head, presents an oblong surface, flattened at each side, for articulation Avith the first phalanx ; it is broader, and extends further forAvards in front than behind ; and longer in the antero-posterior, than in the transverse diameter. On either side of the head is a deep depression, surmounted by a tubercle, for the attachment of the lateral ligament of the metacarpo-phalan- geal joint. The posterior surface, broad and flat, supports the Extensor tendons; and the anterior surface presents a median groove, bounded on each side by a tubercle, for the passage of the Flexor tendons. Peculiar Metacarpal Bones. The metacarpal bone of the thumb is shorter and Avider than the rest, diverges to a greater degree from the carpus, and its palmar surface is directed inwards towards the palm. The shaft is flattened and broad on its dorsal aspect, and does not present the bifurcated ridge peculiar to the other metacarpal bones ; concave from before backwards on its palmar surface. The carpal extremity, or base, presents a concavo-convex surface, for articulation Avith the trapezium, and has no lateral facets. The digital extremity is less convex than that of the other metacarpal bones, broader from side to side than from before backAvards, and ter- minates anteriorly in a small articular eminence on each side, over which play two sesamoid bones. The metacarpal bone of the index finger is the longest, and its base the largest of the other four. Its carped extremity is prolonged upAvards and inAvards ; and its dorsal and palmar surfaces are rough, for the attachment of tendons and liga- ments. It presents four articular facets ; one at the end of the bone, which has an angular depression for articulation Avith the trapezoid ; on the radial side, a flat quadrilateral facet, for articulation with the trapezium ; its ulnar side being prolonged upwards and inAvards, to articulate above Avith the os magnum, inter- nally with the third metacarpal bone. The metacarpal bone of the middle finger is a little less in size than the pre- ceding ; it presents a pyramidal eminence on the radial side of its base (dorsal aspect), which extends upwards behind the os magnum. The carpal articular facet is concave behind, flat and horizontal in front, and corresponds to the os magnum. On the radial side is a smooth, concave facet, for articulation Avith the second metacarpal bone ; and on the ulnar side two small oval facets, for articula- tion Avith the third metacarpal. The metacarpal bone of the ring-finger is shorter and smaller than the pre- ceding, and its base small and quadrilateral; its carpal surface presenting two facets, for articulation with the unciform and os magnum. On the radial side are two oval facets, for articulation with the third metacarpal bone ; and on the ulnar side a single concave facet, for the fifth metacarpal. METACARPUS AND PHALANGES. 109 The metacarpal bone of the little finger may be distinguished by the concavo- convex form of its carpal surface, for articulation Avith the unciform, and from having only one lateral articular facet, Avhich corresponds with the fourth Meta- carpal bone. On its ulnar side is a prominent tubercle for the insertion of the tendon of the Extensor carpi ulnaris. The dorsal surface of the shaft is marked by an oblique ridge, Avhich extends from near the inner side of the upper extremity, to the outer side of the loAver. The outer division of this surface serves for the attachment of the fourth Dorsal interosseous muscle ; the inner division is smooth, and covered by the Extensor tendons of the little finger. Articulations. The first, with the trapezium ; the second, Avith the trapezium, trapezoides, os magnum, and third metacarpal bones ; the third, with the os mag- num, and second and fourth metacarpal bones; the fourth, with the os magnum, unciform, and third and fifth metacarpal bones ; and the fifth, Avith the unciform and fourth metacarpal. Attachment of dluselcs. To the metacarpal bone of the thumb,"three: the Flexor ossis metacarpi pollicis, Extensor ossis metacarpi pollicis, and first Dorsal inter- osseous. To the second metacarpal bone, five : the Flexor carpi radialis, Extensor carpi radialis longior, first and second Dorsal interosseous, and first Palmar inter- osseous. To the third, five : the Extensor carpi radialis brevior, Flexor brevis pollicis, Adductor pollicis, and second and third Dorsal interosseous. To the fourth, three : the third and fourth Dorsal interosseous and second Palmar. To the fifth, four: the Extensor carpi ulnaris, Flexor carpi ulnaris, Flexor ossis meta- carpi minimi digiti, and fourth Dorsal interosseous. Phalanges. The Phalanges are the bones of the fingers; they are fourteen in number, three for each finger and two for the thumb. They are long bones, and present for examination a shaft, and two extremities. The shaft tapers from above down- Avards, is convex posteriorly, concave in front from above downwards, flat from side to side, and marked laterally by rough ridges, Avhich give attachment to the fibrous sheaths of the Flexor tendons. The metacarpal extremity or base, in the first row, presents an oval concave articular surface, broader from side to side. than from before backAvards ; and the same extremity in the other two rows, a double concavity separated by a longitudinal median ridge, extending from before backAvards. The digital extremities are smaller than the others, and terminate, in the first and second i*oav, in tAvo small lateral condyles, separated by a slight groove, the articular surface being prolonged farther fonvards on the palmar, than on the dorsal surface, especially in the first row. The Ungued phalanges are convex on their dorsal, flat on their palmar surfaces; they are recognized by their small size, and from their ungual extremity presenting, on its palmar aspect, a roughened elevated surface of a horseshoe form, "which serves to support the sensitive pulp of the finger. Articulations. The first toav with the metacarpal bones, and the second row of phalanges ; the second roAv, Avith the first and third ; the third with the second roAv. Attachment of Muscles. To the base of the first phalanx of the thumb, four muscles; the Extensor primi internodii pollicis, Flexor bre\ris pollicis, Abductor pollicis, Adductor pollicis. To the second phalanx, two: the Flexor longus pollicis, and the Extensor secundi internodii. To the base of the first phalanx of the index finger, the first Dorsal and the first Palmar interosseous; to that of the middle finger, the second and third Dorsal interosseous; to the ring-finger, the fourth Dorsal and the second Palmar interosseous ; and to that of the little finger, the third Palmar interosseous, the Flexor brevis minimi digiti, and Abductor minimi digiti. To the second phalanges, the Flexor sublimis digitorum, Extensor com- munis digitorum ; and, in addition, the Extensor indicis, to the index finger; the Extensor minimi digiti, to the little finger. To the third phalanges, the Flexor profundus d:gitorum and Extensor communis digitorum. 110 OSTEOLOGY. Development of the Hand. t The Carped bones are each deAreloped by a single centre; at birth they are all cartilaginous. Ossification proceeds in the folloAving order (Fig. 86); in the os magnum and unciform an ossific point appears during the first year, the former preceding the latter; in the cuneiform, at the third year; in the trapezium and semi- lunar, at the fifth year, the former preceding the latter ; in the scaphoid, at the sixth year; in the trapezoid, during the eighth year; and in the pisiform, about the tAvelfth year. Fig. 86.—Plan of the Development of the Hand. The Metacarpal bones are developed each by two centres: one for the shaft, and one for the digital extremity, for the four inner metacarpal bones ; one for the shaft and one for the base, for the metacarpal bone of the thumb, which, in this respect, resembles the phalanges. Ossification commences in the centre of the shaft about the sixth Aveek, and gradually proceeds to either end of the bone; about the third year the digital extremity of the four inner metacarpal bones and the base of the first metacarpal, commences to ossify, and they unite about the twentieth year. The Phalanges are each developed by two centres: one for the shaft and one for the base. Ossification commences in the shaft, in all three rows, at about the sixth week, and gradually involves the Avhole of the bone excepting the upper extremity. Ossification of the base commences in the first row betAveen the third and fourth years, and a year later in those of the second and third row. The two centres become united between the eighteenth and twentieth years. FEMUR. 1 THE LOAVER EXTREMITY. The LoAver Extremities, two in num- ber, are connected with the inferior part of the trunk. They are divided into three parts, the thigh, the leg, and the foot, which correspond "to the arm, the forearm, and hand, in the upper extremity. The thigh is formed of a single bone, the femur. The Femur. The Femur is the longest, largest, and heaviest bone in the skeleton, and almost perfectly cylindrical in the greater part of its extent. In the erect position of the body it is not vertical, but presents a general curvature in the longitudinal direction, Avhich renders the bone convex in front and slightly concave behind; it also gradually inclines from above doAvn- wards and inAvards, approaching its felloAV towards its lower part, but separated from it aboAre by a very considerable in- terval, Avhich corresponds to the entire breadth of the pelvis. The degree of this inclination varies in different persons, and is greater in the female than in the male. The femur, like other long bones, is divisible into a shaft and tAvo extremi- ties. The Upper Extremity presents for ex- amination a head, neck, and the greater and lesser trochanters. The head, Avhich is globular, and forms rather more than a hemisphere, is directed upwards, inwards, and a little forwards, the greater part of its con\Texity being above and in front. Its surface is smooth, coated with cartilage in the recent state, and presents a little behind and beloAv its centre a rough depression, for the attachment of the ligamentum teres. The neck is a flattened pyramidal pro- cess of bone, which connects the head with the shaft. It varies in length and obliquity at various periods of life, and under different circumstances. In the adult male, it forms an obtuse angle with the shaft, being directed upAvards, in- wards, and a little forAvards. In the female, it approaches more nearly a right angle. Occasionally, in very old subjects, and more especially in those greatly de- bilitated, its direction becomes horizontal, so that the head sinks beloAv the level of the trochanter, and its length diminishes Fig. 87.—Right Femur. Anterior Stir 112 OSTEOLOGY. to such a degree, that the head becomes almost continuous Avith the shaft. The neck is flattened from before backwards, contracted in the middle, and broader at its outer extremity, where it is connected with the shaft, than at its summit, where it is attached to the head. It is much broader in the vertical than in the antero- posterior diameter, on account of the greater amount of resistance required in sustaining the weight of the trunk. Its anterior surface, narroAver than the posterior, is perforated by numerous vascular foramina. Its posterior surface is smooth, broader, and more concave than the anterior, and receives towards its outer side the attachment of the capsular ligament of the hip. Its superior border is short and thick, bounded externally by the great trochanter, and its surface perforated by large foramina. Its inferior border, long and narroAv, curves a little backwards, to terminate at the lesser trochanter. The Greater Trochanter is a large irregular quadrilateral eminence, situated at the outer side of the neck, at its junction with the upper part of the shaft. It is directed a little outAvards and backAvards, and rises less high than the head. It presents for examination tAvo surfaces and four borders. Its external surface, quadrilateral in form, is broad, rough, com^ex, and marked by a prominent diagonal line, Avhich extends from the posterior superior to the anterior inferior angle: this line serves for the attachment of the tendon of the Glutaeus medius. Above the line is a triangular surface, sometimes rough for part of the tendon of the same muscle, sometimes smooth for the interposition of a bursa betAveen the tendon and the bone. BeloAv and behind the diagonal line is a smooth triangular surface, over Avhich the tendon of the Glutaeus maximus muscle plays, a bursa being interposed. The internal surface is of much less extent than the external, and presents at its base a deep depression, the digital or trochan- teric fossa, for the attachment of the tendon of the Obturator externus muscle. The superior border is free; it is thick and irregular, and marked by im- pressions for the attachment of the Pyriformis behind, the Obturator internus and Gemelli in front. The inferior border is placed at the point of junction of the trochanter Avith the outer surface of the shaft; it is rough, prominent, slightly curved, and gives attachment to the upper part of the Vastus externus muscle. The anterior border is prominent, someAvhat irregular, as Avell as the surface of bone immediately beloAv it; it affords attachment by its outer part to the Glutseus minimus. The posterior border is very prominent, and appears as a free rounded edge, Avhich forms the back part of the digital fossa. The Lesser Trochanter is a conical eminence, which varies in size in different subjects; it is situated at the lower and back part of the base of the neck. Its base is triangular, and connected with the adjacent parts of the bone by three avell-marked borders ; of these the superior is continuous with the loAver border of the neck ; the posterior, Avith the posterior intertrochanteric line ; and the inferior with the middle bifurcation of the linea aspera. Its summit, Avhich is directed inwards and backAvards, is rough, and gives insertion to the tendon of the Psoas magnus. The Iliacus is inserted into the shaft beloAv the lesser trochanter, be- tween the Vastus internus in front, and the Pectineus behind. A well-marked prominence, but of variable size, situated at the upper and front part of the neck, at its junction with the great trochanter, is called the tubercle of the femur; it is the point of meeting of three muscles, the Glutaeus minimus exter- nally, the Vastus externus below, and the tendon of the Obturator internus and Gemelli above. Running obliquely downwards and inAvards from the tubercle is the spiral line of the femur, or anterior intertrochanteric line ; it winds around the inner side of the shaft, beloAv the lesser trochanter, and terminates in the linea aspera, about tAvo inches beloAv this eminence. Its upper half is rough, and affords attachment to the capsular ligament of the hip joint; its loAver half is less promi- nent and gives attachment to the upper part of the Vastus internus. The posterior intertrochanteric line is very prominent, and runs from the summit of the great trochanter dowmvards and inAvards to the upper and back part of the lesser tro- chanter. Its upper half forms the posterior border of the great trochanter. A FEMUR. well-marked eminence commences about the centre of the posterior intertrochan- teric line, and passes vertically down- Avards for about tAvo inches along the back part of the shaft: it is called the linea quadrati, and gives attachment to the Quadratus femoris, and a few fibres of the Adductor magnus muscle. The Shaft,almost perfectly cylindrical in form, is a little broader above than in the centre, and somewhat flattened from before backAvards below. It is curved from before backwards, smooth and convex in front, and strengthened behind by a pro- minent longitudinal ridge, the linea aspera. It presents for examination three borders separating three surfaces. Of the three borders, one, the linea aspera, is posterior, the other two are placed laterally. The linea aspera- (Fig. 88) is a promi- nent longitudinal ridge or crest, present- ing on the middle third of the bone an ex- ternal lip, an internal lip, and a rough intermediate space. A little above the centre of the shaft, this crest divides into three lines; the most external one be- comes veryrough,and is continued almost vertically upAvards to the base of the great trochanter; the middle one,the least distinct, is continued to the base of the trochanter minor; and the internal one is lost above in the spiral line of the femur. Below, the linea aspera divides into two bifurcations, Avhich inclose be- tAveen them a triangular space (the po- pliteal space), upon which rests the popliteal artery. Of these two bifur- cations, the outer branch is the most prominent, and descends to the summit of the outer condyle. The inner branch is less marked, presents a broad and shallow groove for the passage of the femoral artery, and terminates at a small tubercle at the summit of the internal condyle. To the inner lip of the linea aspera, its AA'hole length, is attached the Vastus internus; and to the Avhole length of the outer lip the A'astus externus. The Adductor magnus is also attached to the Avhole length of the linea aspera, being connected with the outer lip above, and the inner lip beloAv. BetAveen the Vastus externus and the Adductor magnus are attached tAvo muscles, viz., the Glutasus maximus above, and the short head of the 10 Ill OSTEOLOGY. Biceps beloAV. BetAveen the Adductor magnus and the Vastus internus four muscles are attached: the Iliacus and Pectineus above (the latter to the middle division of the upper bifurcation); below these, the Adductor brevis and Adductor longus. The linea aspera is perforated a little beloAv its centre by the nutritious canal, which is directed obliquely from below upwards. The tAvo lateral borders of the femur are only very slightly marked, the external extending from the anterior inferior angle of the great trochanter to the anterior extremity of the external condyle; the internal passes from the spiral line, at a point opposite the trochanter minor, to the anterior extremity of the internal condyle. The internal border marks the limit of attachment of the Cru- raeus muscle internally. The anterior surface includes that portion of the shaft Avhich is situated be- tween the tAvo lateral borders. It is smooth, convex, broader above and below than in the centre, slightly twisted, so that its upper part is directed forwards and a little outAvards, its lower part forAvards and a little inAvards. The upper three- fourths of this surface serve for the attachment of the Cruraeus; the lower fourth is separated from this muscle by the intervention of the synovial membrane of the knee joint, and affords attachment to the Subcruraeus to a small extent. The external surface includes the portion of bone betAveen the external border and the outer lip of the linea aspera; it is continuous above with the outer surface of the great trochanter, below with the outer surface of the external condyle: to its upper three-fourths is attached the outer portion of the Crurreus muscle. The internal surface includes the portion of bone between the internal border and the inner lip of the linea aspera; it is continuous above Avith the loAver border of the neck, beloAV Avith the inner side of the internal condyle: it is covered by the Vastus internus muscle. The Lotver Extremity, larger than the upper, is of a cuboid form, flattened from before backAvards, and divided by an interval presenting a smooth depression in front, and a notch of considerable size behind, into two large eminences, the condyles. The interval is called the intercondyloid notch. The externed con- dyle is the most prominent anteriorly, and is the broadest both in the antero- posterior and transverse diameters. The internal condyle is the narroAvest, longest, and most prominent internally. This difference in the length of the two condyles depends upon the obliquity of the thigh bones, in consequence of their separation above at the articulation with the pelvis. If the femur is held in this oblique position, the surfaces of the tAvo condyles Avill be seen to be nearly hori- zontal. The tAvo condyles are joined together anteriorly, and form a smooth trochlear surface, the external border of Avhich is more prominent, and ascends higher than the internal one. This surface articulates Avith the patella. It pre- sents a median groove, which extends doAvmvards and backAvards to the inter- condyloid notch; and tAvo lateral convexities, of Avhich the external is the broader, more prominent, and prolonged farther upAvards upon the front of the outer condyle. The intercondyloid notch lodges the crucial ligaments; it is bounded laterally by the opposed surfaces of the tAvo condyles, and in front by the loAver end of the shaft. Outer Condyle. The outer surface of the external condyle presents, a little behind its centre, an eminence, the outer tuberosity; it is less convex and pro- minent than the inner tuberosity, and gives attachment to the external lateral ligament of the knee. Immediately beneath it is a groove, which commences at a depression a little behind the centre of the lower border of this surface : the depression is for the tendon of origin of the Popliteus muscle ; the groove in which this tendon is contained is smooth, covered Avith cartilage in the recent state, and runs upwards and backwards to the posterior extremity of the condyle. The inner surface of the outer condyle forms one of the lateral boundaries of the intercondyloid notch, and gives attachment, by its posterior part, to the anterior crucial ligament. The inferior surface is convex, smooth, and broader than that of the internal condyle. The posterior extremity is convex and smooth : just FEMUR. 115 above the articular surface is a depression, for the tendon of the outer head of the Gastrocnemius. Diner Condyle. The inner surface of the inner condyle presents a convex eminence, the inner tuberosity, rough, for the attachment of the internal lateral ligament. Above this tuberosity, at the termination of the inner bifurcation of the linea aspera, is a tubercle, for the insertion of the tendon of the Adductor magnus ; and behind and beneath the tubercle a depression, for the tendon of the inner head of the Gastrocnemius. The outer side of the inner condyle forms one of the lateral boundaries of the intercondyloid notch, and gives attachment, by its anterior part, to the posterior crucial ligament. Its inferior or articular surface is convex, and presents a less extensive surface than the external condyle. Structure. Like that of the other cylindrical bones, the linea aspera is com- posed of a very dense, ivory-like, compact tissue. Articulations. AVith three bones: the os innominatum, tibia, and patella. Development (Fig. 89). The femur Fig. 89.—Plan of the Development of the Femur. by Five Centres. Appears at p?y. J'-'-ShftuloutW^f: Appears atcndof1*yT Joins Shaft alnut t8*y' Appcarsm-iA* yr *S ./oui.s-Shaft aioiit 18* yC is developed by five centres: one for the shaft, one for each extre- mity, and one for each trochanter. Of all the long bones, it is the first to sIioav traces of ossification : this first commences in the shaft, at about the fifth Aveek of foetal life, the centres of ossification in the epiphyses appear- ing in the folloAving order. First, in the lower end of the bone, at the ninth month of fcetal life ; from this the condyles and tuberosities are formed; in the head, at the end of the first year after birth; in the great trochanter during the fourth 1 1 year; and in the lesser trochanter, betAveen the thirteenth and four- teenth. The order in which the epiphyses are joined to the shaft, is the direct reverse of their appear- ance ; their junction does not com- mence until after puberty, the lesser trochanter being first joined, then the greater, then the head, and lastly, the inferior extremity (the first in Avhich ossification com- menced), Avhich is not united until the twentieth year. Attachment of Muscles. To the great trochanter, the Glutasus medius, Gluteus minimus, Pyriformis, Obturator internus, Obturator externus, Gemellus superior, Gemellus inferior, and Quadratus femoris. To the lesser trochanter, the Psoas magnus, and the Iliacus below it. To the shaft, its posterior surface, the Vastus externus, Gluteus maximus, short head of the Biceps, Vastus internus. Adductor magnus, Pectineus, Adductor breA'is, and Adductor longus; to its anterior surface, the Crurseus and Subcruneus. To the condyles, the Gastrocnemius, Plantaris, and Popliteus. THE LEG. A'/mears at Q: {/"talU°«r'rExiremW Joins ShaftoeZO' The Leg consists of three bones: the Patella, a large sesamoid bone, placed in front of the knee, analogous to the olecranon process of the ulna; and the Tibia and Fibula. 116 OSTEOLOGY. The Patella. (Figs. 90, 91.) Fig. 90.—Right Patella, Anterior Surface. Fig. 91.—Posterior Surface. The Patella is a small, flat, triangular bone, situated at the anterior part of the knee joint. It resembles the sesamoid bones, from being developed in the tendon of the Quadriceps extensor; but, in relation with the tibia, it may be regarded as analogous to the olecranon process of the ulna, Avhich occasionally exists as a sepa- rate piece, connected to the shaft of that bone by a continuation of the tendon of the Triceps muscle. It presents an anterior and posterior surface, three borders, a base, and an apex. The anterior surface is convex, perforated by small apertures, for the passage of nutrient vessels, and marked by numerous rough, longitudinal striae. This surface is covered, in the recent state by an expansion from the tendon of the quadriceps extensor, separated from the integument by a synovial bursa, and gives attachment below to the ligamentum patellae. The posterior surface presents a smooth, oval-shaped, articular surface, covered Avith car- tilage in the recent state, and divided into two facets by a vertical ridge, Avhich descends from the superior to- wards the inferior angle of the bone. The ridge cor- responds to the groove on the trochlear surface of the femur, and the tAvo facets to the articular surfaces of the tAvo condyles; the outer facet, for articulation with the outer condyle, being the broader and deeper, serves to indicate the leg to Avhich the bone belongs. This surface presents, inferiorly, a rough, convex, non-arti- cular depression, the loAver half of Avhich gives attach- ment to the ligamentum patellae ; the upper half being separated from the head of the tibia by adipose tissue. Its superior and lateral borders give attachment to the tendon of the Quadriceps extensor ; to the superior border, that portion of the tendon Avhich is derived from the Rectus and Cruraeus muscles; and to the lateral borders, the portion derived from the external and in- ternal Vasti muscles. The base or superior border, is thick, directed upwards, and cut obliquely at the expense of its outer surface; it receives the attachment, as already mentioned, of part of the Quadriceps extensor tendon. The Apex is pointed, and gives attachment to the ligamentum patellae. Structure. It consists of loose cancellous tissue, covered by a thin compact lamina. Development. By a single centre, Avhich makes its appearance, according to Beclard, about the third year. In two instances I have seen this bone cartilagi- nous throughout, at a much later period (six years). More rarely, the bone is developed by two centres, placed side by side. Articulations. AVith the tAvo condyles of the femur. Attachment of 3Iuscles. Four muscles are attached to the patella, viz., the Rectus, Cruroeus, Vastus internus, and Vastus externus. The tendons of these muscles joined at their insertion constitute the Quadriceps extensor cruris. The Tibia. The Tibia (Figs. 92, 93) is situated at the anterior and inner side of the leg, and, excepting the femur, is the longest and largest bone in the skeleton. It is pris- moid in form, expanded above, Avhere it enters into formation with the knee joint, and more slightly below. In the male, its direction is vertical, and parallel with TIBIA. 117 the bone of the opposite side, but in the female it has a slight oblique direction doAvnwards and outwards, to compensate for the oblique direction of the femur inwards. It presents for exami- nation a shaft and two extre- mities. The Superior Extremity, or head, is large and expanded on each side into two lateral emi- nences, the tuberosities. Supe- riorly, the tuberosities present tAvo smooth concave surfaces, which articulate with the con- dyles of the femur; the internal articular surface is longer than the external, oval from before backwards, to articulate Avith the internal condyle; the external one being broader, flatter, and more circular, to articulate with the external condyle. BetAveen the tAvo articular surfaces, and nearer the posterior than the anterior aspect of the bone, is an eminence, the spinous process of the tibia, surmounted by a pro- minent tubercle on each side, which gives attachment to the extremities of the semilunar fibro-cartilages; and in front and behind the spinous process, a rough depression for the attach- ment of the anterior and poste- rior crucial ligaments and the semilunar cartilages. Anteriorly the tuberosities are continuous with one another, presenting a large and someAvhat flattened triangular surface, broad above, and perforated by large vascular foramina, narrow below, Avhere it terminates in a prominent oblong elevation of large size, the tubercle of the tibia; the lower half of this tubercle is rough for the attachment of the ligamentum patella?; the upper half is a smooth facet corres- ponding, in the recent state, with a bursa which separates this ligament from the bone. Poste- riorly, the tuberosities are sepa- rated from each other above by a shallow depression, the popli- teal notch, which gives attach- Fig. 9*2.—Bones of the Right Leg. Anterior Surface. Jl e a £ StyUiJ proecffH* TZxtavna! Mallrntu* 118 OSTEOLOGY. ment to the posterior crucial ligament. The posterior surface of the inner tuberosity presents a deep transverse groove, for the insertion of the tendon of the Semimembranosus; and the posterior surface of the outer one, a flat articular facet, nearly circular in form, directed doAvmvards, backwards, and outAvards, for articulation Avith the fibula. The lateral surfaces are convex and rough; the internal one, the most prominent, gives attachment beloAV to the internal lateral ligament. The Shaft of the tibia is of a triangular prismoid form, broad above, gradually decreasing in size to the commencement of its loAver fourth, its most slender part, and then enlarging again towards its loAver extremity. It presents for examination three surfaces and three borders. The anterior border, the most prominent of the three, is called the crest of the tibia, or, in popular language, the shin; it commences above at the tubercle, and terminates beloAv at the anterior margin of the inner malleolus. This border is very prominent in the upper two-thirds of its extent, smooth and rounded below. It presents a very flexuous course, being curved outAvards above, and inwards beloAv; it gives attachment to the deep fascia of the leg. The internal border is smooth and rounded above and below, but more promi- nent in the centre; it commences at the back part of the inner tuberosity, and terminates at the posterior border of the internal malleolus; its upper third gives attachment to the internal lateral ligament of the knee, and to some fibres of the Popliteus muscle; its middle third, to some fibres of the Soleus and Flexor longus digitorum muscles. The externed border is thin and prominent, especially its central part, and gives attachment to the interosseous membrane; it commences above in front of the fibular articular facet, and bifurcates below, forming the boundaries of a triangular rough surface, for the attachment of the inferior interosseous ligament, connecting the tibia and fibula. The internal surface is smooth, convex, and broader above than beloAv; its upper third, directed forwards and inwards, is covered by the aponeurosis derived from the tendon of the Sartorius, and by the tendons of the Gracilis and Semitendinosus, all of Avhich are inserted nearly as far forAvards as the anterior border; in the rest of its extent it is subcutaneous. The externed surface is narrower than the internal; its upper two-thirds present a shallow groove for the attachment of the Tibialis anticus muscle; its lower third is smooth, convex, curves gradually forAvards to the anterior part of the bone, and is covered from Avithin outwards by the tendons of the following muscles: Tibialis anticus, Extensor proprius pollicis, Extensor longus digitorum, Peroneus tertius. The Posterior surface (Fig. 9-3) presents at its upper part a prominent ridge, the oblique line of the tibia, which extends from the back part of the articular facet for the fibula, obliquely downwards, to the internal border, at the junction of its upper and middle thirds. It marks the limit for the insertion of the Popliteus muscle, and serves for the attachment of the popliteal fascia, and part of the Soleus, Flexor longus digitorum, and Tibialis posticus muscles; the triangular conca\Te surface above, and to the inner side of this line, gives attachment to the Popliteus muscle. The middle third of the posterior surface is divided by a vertical ridge into two lateral halves; the ridge is Avell marked at its commence- ment at the oblique line, but becomes gradually indistinct beloAv; the inner and broadest half gives attachment to the Flexor longus digitorum, the outer and narroAvest, to part of the Tibialis posticus. The remaining part of the bone is covered by the Tibialis posticus, Flexor longus digitorum, and Flexor longus pollicis muscles. Immediately beloAV the oblique line is the medullary foramen, Avhich is directed obliquely doAvnwards. The Lower Extremity, much smaller than the upper, is someAvhat quadrilateral in form, and prolonged doAvnwards on its inner side, into a strong process, the internal malleolus. The inferior surface of the bone presents a quadrilateral smooth surface, for articulation with the astragalus; narroAv internally, where it becomes continuous with the articular surface of the inner malleolus, broader TIBIA. 119 externally, and traversed from before backwards by a slight elevation, separating two lateral depressions. The anterior sur- face is smooth and rounded above, and covered by the ten- dons of the Extensor muscles of thetoes; its loAver margin presents a rough transverse depression, for the attachment of the anterior ligament of the ankle joint. The posterior surface presents a superficial groove directed obliquely dowmvards and in- wards, continuous Avith a simi- lar groove on the posterior ex- tremity of the astragalus; it serves for the passage of the tendon of the Flexor longus pollicis. The externed surface presents a triangular rough de- pression, the lower part of which, in some bones, is smooth, covered with cartilage in the recent state, and articulates Avith the fibula; the remaining part is rough for the attachment of the inferior interosseous ligament, AAThich connects it Avith the fibula. This surface is bounded by two prominent ridges, continuous above Avith the interosseous ridge; they afford attachment to the anterior and posterior tibio-fibular ligaments. The internal surface is prolonged dowmvards to form a strong pyramidal-shaped process, flat- tened from without inwards, the inner malleolus; its inner surface is convex and subcutaneous. Its outer surface, smooth and slight- ly concave, deepens the articular surface for the astragalus. Its anterior border is rough, for the attachment of ligamentous fibres. Its posterior border presents a broad and deep groove, directed obliquely dowmvards, and in- wards ; it is occasionally double, and transmits the tendons of the Tibialis posticus and Flexor longus digitorum muscles. Its summit is marked by a rough depression behind, for the attach- ment of the internal lateral liga- ment of the ankle joint. Fig. 93.—Bones of the Right Lf Posterior Surface. 120 OSTEOLOGY Structure. Like that of the other long bones. Development. l>y three centres (Fig. 94): one for the shaft, and one for each extremity. Ossification commences in the centre of the shaft about the same time as in the femur, the fifth week, and Fig. 94.—Plan of the Development of the Tibia. By Three Centres. Appears at birtk—* er extreme Appears at 2**^». Joins Sliaft i he-ut Tains Shaft 20$ u.f t bout °'ierer extremity gradually extends toAvards either ex- tremity. The centre for the upper epiphysis appears at birth; it is flat- tened in form, and has a thin tongue- shaped process in front, Avhich forms the tubercle. That for the lower epiphysis appears in the second year. The lower epiphysis joins the shaft at about the twentieth year, and the upper one about the tAventy-fifth year. Tavo additional centres occa- sionally exist, one for the tongue- shaped process of the upper epiphysis, the tubercle, and one for the inner malleolus. Articulations. AVith three bones: the femur, fibula, and astragalus. Attachment of 3Diseles. To the inner tuberosity, the Semimembra- nosus. To the outer tuberosity, the Tibialis anticus and Extensor longus digitorum; to the shaft: its internal surface, the Sartorius, Gracilis, and Semitendinosus; to its external sur- face, the Tibialis anticus : to its poste- rior surface, the Popliteus, Soleus, Flexor longus digitorum, and Tibialis posticus; to the tubercle, the ligamentum patellae. The Fibula. The Fibula (Figs. 92, 93) is situated at the outer side of the leg. It is the smaller of the tAvo bones, and, in proportion to its length, the most slender of all the long bones; it is placed nearly parallel with the tibia, its lower extremity inclining a little forwards, so as to be on a plane anterior to that of the upper end. It presents for examination a shaft and tAvo extremities. The Superior Extremity or Head is of an irregular rounded form, presenting, above, a flattened articular facet, directed upAvards and inAvards, for articulation with a corresponding facet on the external tuberosity of the tibia. On the outer side is a thick and rough prominence, continued behind into a pointed eminence, the styloid process, Avhich projects upwards from the posterior part of the head. The prominence above mentioned gives attachment to the tendon of the Biceps muscle, and to the long external lateral ligament of the knee, the ligament dividing this tendon into two parts. The summit of the styloid process gives attachment to the short external lateral ligament. The remaining part of the circumference of the head is rough, for the attachment, in front, of the anterior superior tibio- fibular ligament, and the upper and anterior part of the Peroneus longus; and behind, to the posterior superior tibio-fibular ligament, and the upper fibres of the outer head of the Soleus muscle. The Lower Extremity, called the malleolus externus, is of a pyramidal form, some- Avhat flattened from Avithout inAvards, and is longer, and descends lower than the internal malleolus. Its external surface is convex, subcutaneous, and continuous Avith a triangular (also subcutaneous) surface on the outer side of the shaft. The interned surface presents in front a smooth triangular facet, broader above than beloAv, convex from above doAvmvards, Avhich articulates Avith a corresponding FIBULA. 121 surface on the outer side of the astragalus. Behind and beneath the articular surface is a rough depression, Avhich gives attachment to the posterior fasciculus of the external lateral ligament of the ankle. Its anterior border is thick and rough, and marked beloAv by a depression for the attachment of the anterior fasciculus of the external lateral ligament. The posterior border is broad and marked by a shalloAV groove, for the passage of the tendons of the Peroneus longus and brevis muscles. Its summit is rounded, and gives attachment to the middle fasciculus of the external lateral ligament. The Shaft presents three surfaces, and three borders. The anterior border com- mences above in front of the head, runs vertically doAvmvards to a little beloAv the middle of the bone, and then curving a little outwards, bifurcates beloAv into two lines, Avhich bound the triangular subcutaneous surface immediately above the outer side of the malleolus externus. It gives attachment to an intermuscular septum, which separates the muscles on the anterior surface from those on the external. The internal border, or interosseous ridge, is situated close to the inner side of the preceding; it runs nearly parallel with it in the upper third of its extent, but diverges from it so as to include a broader space in the loAver tAvo- thirds. It commences above just beneath the head of the bone (sometimes it is quite indistinct for about an inch below the head), and terminates beloAV at the apex of a rough triangular surface immediately above the articular facet of the external -mal- leolus. It serves for the attachment of the interosseous membrane, and separates the extensor muscles in front, from the flexor muscles behind. The portion of bone included betAveen the anterior and interosseous lines forms the anterior surface. The posterior border is sharp and prominent; it commences above at the base of the styloid process, and terminates below in the posterior border of the outer mal- leolus. It is directed outAvards above, backAvards in the middle of its course, backAvards and a little inwards beloAV, and gives attachment to an aponeurosis which separates the muscles on the outer from those on the inner surface of the shaft. The portion of bone included betAveen this line and the interosseous ridge forms the internal surface. Its upper three-fourths are subdivided into tAvo parts, an anterior and a posterior, by a very prominent ridge, the oblique line of the fibula, which commences above at the inner side of the head, and terminates by being continuous Avith the interosseous ridge at the lower fourth of the bone. It attaches an aponeurosis Avhich separates the Tibialis posticus from the Soleus above, and the Flexor longus pollicis beloAV. This ridge sometimes ceases just before approaching the interosseous ridge. The anterior surface is the interval between the anterior and interosseous lines. It is extremely narroAv and flat in the upper third of its extent; broader and grooved longitudinally in its loAver third ; it serves for the attachment of three muscles, the Extensor longus digitorum, Peroneus tertius, and Extensor longus pollicis. The external surface, much broader than the preceding, is directed outwards in the upper tAvo-thirds of its course, backAvards in the lower third, Avhere it is con- tinuous with the posterior border of the external malleolus. The surface is com- pletely occupied by the Peroneus longus and brevis muscles. The internal surface is the interval betAveen the interosseous ridge and the posterior border, and occupies nearly two-thirds of the circumference of the bone. Its upper three-fourths are divided into an anterior and a posterior portion by a very prominent ridge already mentioned, the oblique line of the fibula. The anterior portion is directed inwards, and is grooved for the attachment of the Tibialis posticus muscle. The posterior portion is continuous beloAv Avith the rough triangular surface above the articular facet of the outer malleolus; it is directed backAvards above, backAvards and inwards at its middle, directly inAvards beloAv. Its upper fourth is rough, for the attachment of the Soleus muscle; its lower part presents a triangular rough surface, connected to the tibia by a strong interosseous ligament, and between these tAvo points, the entire surface is coArered by the fibres of origin of the Flexor longus pollicis musele. At about the middle of this surface is the nutritious foramen, which is directed doAvnwards. 122 OSTEOLOGY. In order to distinguish the side to Avhich the bone belongs, hold it with the loAver extremity doAvmvards, and the broad groove Fibula. App-™ about i+-'iip 'nitis about £5!'' " 1ihTb^eSen8.t0fthefor the Peronei tendons backwards, towards the holder; the triangular subcutaneous surface will .«,f txtr-e^ then be directed to the side to which the bone belongs. Articulations. AVith two bones : the tibia and astragalus. Development. By three centres (Fig. 95): one for the shaft, and one for each extremity. Ossi- fication commences in the shaft about the sixth week of foetal life, a little later than in the tibia, and extends gradually towards the extremities. At birth both ends are cartilaginous. Ossification commences in the loAver end in the second year, and in the upper one about the fourth year. The lower epiphysis, the first in Avhich ossification commences, becomes united to the shaft about the tAventieth year, contrary to the laAv Avhich appears to prevail Avith regard to the junction of the epiphyses Avith the shaft; the upper one is joined about the tAventy-fifth year. Attachment of Muscles. To the head, the Biceps, Soleus, and Peroneus longus ; to the shaft, its anterior surface, the Extensor longus digito- rum, Peroneus tertius, and Extensor longus pol- licis ; to the internal surface, the Soleus, Tibialis posticus, and Flexor longus pollicis ; to the exter- nal surface, the Peroneus longus and brevis. Avpea rsatZ V4y4 -Un ites alout 20^ if THE FOOT. The foot (Figs. 96, 97) is the terminal part of the inferior extremity; it serves to support the body in the erect posture, and as an important instrument of loco- motion. It consists of three divisions : the Tarsus, Metatarsus, and Phalanges. The Tarsus. The bones of the Tarsus arc seven in number; viz., the calcaneum, or os ealcis, astragalus, cuboid, scaphoid, internal, middle, and external cuneiform bones. These bones may be conveniently arranged into tAvo lateral i*oavs. The outer row, remarkable for its great solidity and strength, forms the basis of support to the foot; it consists of tAvo bones, the os ealcis and cuboid. The inner row, which contributes chiefly to its elasticity, is formed by the astragalus, scaphoid, and three cuneiform bones. The Calcaneum. The Calcaneum, or Os Cedcis, is the largest bone of the tarsus. It is irregu- larly cuboidal in form, and situated at the lower and back part of the foot. It presents for examination six surfaces : superior, inferior, external, internal, ante- rior, and posterior. The superior surface is formed behind, of the upper edge of that process of the os ealcis which projects backAvards to form the heel. This process varies in length in different individuals ; it is convex from side to side, concave from before backwards, and corresponds above to a mass of adipose substance placed in front of the tendo Achillis. In the middle of this surface are tAvo (sometimes three) articular facets, separated by a broad shalloAV groove, directed obliquely for- wards and outAvards, and rough for the attachment of the interosseous ligament connecting the astragalus and os ealcis. Of these tAvo articular surfaces, the TARSUS. 123 Fig. 96.—Bones of the Right Foot. Dorsal Surface. Groove for PERONEU O-roore for peroneus PERONEUS T! PERONEUS EREV Cniore for Tendon rf FLEXOR LONCUS POLL.CIS Tars as Metatarsus Innermost U/uton cf EXT.BREVIS DIGITORUM FJtM/lanqes ■■get LONCUS PULLICIS 124 OSTEOLOGY. external is the larger, and situated upon the body of the bone; it is of an oblong form, broader behind than in front, and convex from before backwards. The internal articular surface is supported on a projecting process of bone, called the lesser process of the calcaneum (sustentaculum tali); it is of an oblong form, con- cave longitudinally, and sometimes subdivided into tAvo, Avhich differ in size and shape. More anteriorly is seen the upper surface of the greater process, marked by a rough depression for the attachment of numerous ligaments, and the tendon of origin of the Extensor brevis digitorum muscle. The inferior surface is narroAv, rough, uneven, broader behind than in front, and convex from side to side; it is bounded posteriorly by tAvo tuberosities, separated by a rough depression: the externed, small, prominent, and rounded, gives attachment to part of the Abductor minimi digiti; the internal, broader and larger, for the support of the heel, gives attachment, by its prominent inner margin, to the Abductor pollicis, and in front to the Flexor brevis digitorum muscles, and the depression betAveen the tubercles to the Abductor minimi digiti, and plantar fascia. The rough surface in front of these tubercles gives attach- ment to the long plantar ligament; and to a prominent tubercle nearer the anterior part of the bone, as well as to the transverse groove in front, is attached the short plantar ligament. The externed surface is subcutaneous, and presents near its centre a tubercle, for the attachment of the middle fasciculus of the external lateral ligament. Behind the tubercle is a broad, smooth surface, giving attachment, at its upper and anterior part, to the external astragalo-calcanean ligament; and in front a narroAv surface marked by two oblique grooves, separated by an elevated ridge: the superior groove transmits the tendon of the Peroneus brevis; the inferior, the tendon of the Peroneus longus; the intervening ridge gives attachment to a pro- longation from the external annular ligament. The interned surface presents a deep concavity, directed obliquely downwards and fonvards, for the transmission of the plantar vessels, and nerves and Flexor tendons into the sole of the foot; it affords attachment to part of the Flexor accessorius muscle. Its surface presents in front an eminence of bone, the lesser process, Avhich projects horizontally inwards from the upper and front part of this surface. This process is concave above, and supports the anterior articular surface of the astragalus; beloAV, it is convex, and grooved for the tendon of the Flexor longus pollicis. Its free margin is rough, for the attachment of ligaments. The anterior surface, of a somewhat triangular form, is smooth, concavo-con- vex, and articulates with the cuboid. It is surmounted, on its outer side, by a rough prominence, Avhich forms an important guide to the surgeon in the per- formance of Chopart's operation. The posterior surface is rough, prominent, convex, and wider below than above. Its loAver part is rough, for the attachment of the tendo Achillis ; its upper part smooth, coated with cartilage, and corresponds to a bursa which separates this tendon from the bone. Articulations. With tAvo bones: the astragalus and cuboid. Attachment of Muscles. Part of the Tibialis posticus, the tendo Achillis, Plan- taris. Abductor pollicis, Abductor minimi digiti, Flexor brevis digitorum, Flexor accessorius, and Extensor brevis digitorum. The Cuboid. The Cuboid bone is placed on the outer side of the foot, immediately in front of the os ealcis. It is of a pyramidal shape, its base being directed upAvards and inAvards, its apex doAvmvards and outAvards. It may ahvays be knoAvn from all the other tarsal bones, by the existence of a deep groove on its under surface, for the. tendon of the Peroneus longus muscle. It presents for examination six sur- faces : three articulai-, and three non-articular: the non-articular surfaces are superior, inferior, and external. TARSUS. 125 The superior or dorsal surface, directed upwards and outAvards, is rough, for the attachment of numerous ligaments. The inferior or plantar surface presents in front a deep groove, Avhich runs obliquely from without, forwards and inAvards; it lodges the tendon of the Peroneous longus, and is bounded behind by a promi- nent ridge, terminating externally in an eminence, the tuberosity of the cuboid, the surface of which presents a convex facet, for articulation with the sesamoid bone of the tendon contained in the groove. The ridge and surface of bone behind it are rough, for the attachment of the long and short plantar ligaments. The externed surface, the smallest and narroAvest of the three, presents a deep notch, formed by the commencement of the peroneal groove. The articular surfaces are the posterior, anterior, and internal. The posterior is a smooth, triangular, concavo-convex surface, for articulation with the anterior surface of the os ealcis. The anterior, of smaller size, but also irregularly trian- gular, is divided by a vertical ridge into two facets : the inner quadrilateral in form, to articulate with the fourth metatarsal bone; the outer larger and more triangular, for articulation Avith the fifth metatarsal. The internal surface is broad, rough, irregularly quadrilateral, presenting at its middle and upper part a small oval facet, for articulation with the external cuneiform bone; and behind this (occasionally) a smaller facet, for articulation with the scaphoid ; it is rough in the rest of its extent, for the attachment of strong interosseous ligaments. To ascertain to Avhich foot it belongs, hold the bones so that its under surface, marked by the peroneal groove, looks downwards, and the large concavo-convex articular surface backwards, toAvards the holder; the small non-articular surface marked by the commencement of the peroneal groove will point to the side to which the bone belongs. Articulations. With four bones: the os ealcis, external cuneiform, and the fourth and fifth metatarsal bones, occasionally with the scaphoid. Attachment of Muscles. Part of the flexor brevis pollicis. The Astragalus. The Astragalus (Fig. 96), next to the os ealcis, is the largest of the tarsal bones. It is placed at the middle and upper part of the tarsus, supporting the tibia above, articulating with the malleolus on either side, resting below upon the os ealcis, and joined in front to the scaphoid. This bone may easily be recognized by its large rounded head, the broad articular facet on its upper convex surface, and by the ' two articular facets separated by a deep groove on its under concave surface. It presents six surfaces for examination. The superior surface presents, behind, a broad smooth trochlear surface, for articulation with the tibia; it is broader in front than behind, convex from before backwards, slightly concave from side to side. In front of the trochlea is the upper surface of the neck of the astragalus, rough for the attachment of liga- ments. The inferior surface presents tAvo articular facets separated by a deep groove. The groove runs obliquely forAvards and outAvards, becoming gradually broader and deeper in front: it corresponds with a similar groove upon the upper surface of the os ealcis, and forms, Avhen articulated Avith that bone, a canal, filled up in the recent state by the calcaneo-astragaloid interosseous ligament. Of the two articular facets, the posterior is the larger, of an oblong form, and deeply concave from side to side; the anterior, although nearly of equal length, is nar- l'OAver, of an elongated oval form, convex from side to side, and often subdivided into two by an elevated ridge ; the posterior articulates Avith the lesser process of the os ealcis; the anterior, with the upper surface of the calcaneo-scaphoid ligament. The internal surface presents at its upper part a pear-shaped articular facet for the inner malleolus, continuous above Avith the trochlear surface; beloAV the articular sur- face is a rough depression, for the attachment of the deep portion of the internal lateral ligament. The external surface presents a large triangular facet, concave from above downwards, for articulation with the external malleolus ; it is con- 126 OSTEOLOGY. Fig. 97.—Bones of the Right Foot. Plantar Surface. Tu le rclt Scaphoid is POLLICIS TIBIALIS «U ■LEXOR BREVIS Sc ABDUCTOR NIMi DICITI FLEXOR LONCUS / O1C1TORUM TARSUS. 127 tinuous above with the trochlear surface: in front is a deep rough margin, for the attachment of the anterior fasciculus of the external lateral ligament. The anterior surface, convex and rounded, forms the head of the astragalus ; it is smooth, of an oval form, and directed obliquely inAvards and dowmvards; it is continuous beloAV Avith that part of the anterior facet on the under surface Avhich rests upon the calcaneo-scaphoid ligament. The head is surrounded by a con- stricted portion, the neck of the astragalus. The posterior surface is narroAv, and traversed by a groove, Avhich runs obliquely doAvmvards and inAvards, and trans- mits the tendon of the Flexor longus pollicis. To ascertain to Avhich foot it belongs, hold the bone with the broad articular surface upAvards, and the rounded head forAvards ; the lateral triangular articular surface for the external malleolus will then point to the side to Avhich the bone belongs. Articulations. With four bones: tibia, fibula, os ealcis, and scaphoid. The Scaphoid. The Scaphoid or Navicular bone, so called from its fancied resemblance to a boat, is situated at the inner side of the tarsus, betAveen the astragalus behind and the three cuneiform bones in front. This bone may be distinguished by its boat- like form, being concave behind, convex, and subdivided into three facets in front. The anterior surface, of an oblong form, is convex from side to side, and sub- divided by two ridges into three facets, for articulation Avith the three cuneiform bones. The posterior surface is oval, concave, broader externally than internally, and articulates with the rounded head of the astragalus. The superior surface is convex from side to side, and rough for the attachment of ligaments; the inferior, someAvhat concave, irregular, and rough for the attachment of liga- ments. The internal surface presents a rounded tubercular eminence, the tuberosity of the scaphoid, Avhich giA'es attachment to part of the tendon of the Tibialis posticus. The external surface is broad, rough, and irregular, for the attachment of ligamentous fibres, and occasionally presents a small facet for articu- lation with the cuboid bone. To ascertain to Avhich foot it belongs, hold the bone Avith the concave articular surface backAvards, and the broad dorsal surface upAvards; the broad external surface will point to the side to which the bone belongs. Articulations. With four bones : astragalus and three cuneiform ; occasionally also with the cuboid. Attachment of Muscles. Part of the Tibialis posticus. The Cuneiform Bones have received their name from their Avcdge-like form. They form the most anterior toav of the inner division of the tarsus, being placed betAveen the scaphoid behind, the three innermost metatarsal bones in front, and the cuboid externally. They are called the first, second, and third, counting from the inner to the outer side of the foot, and from their position, internal, middle. and externed. The Internal Cuneiform. The Internal Cuneiform is the largest of the three. It is situated at the inner side of the foot, betAveen the scaphoid behind and the base of the first metatarsal in front. It may be distinguished by its large size, as compared Avith the other two, and from its more irregular Avcdge-like form. It presents for examination six surfaces. The internal surface is subcutaneous, and forms part of the inner border of the foot; it is broad, quadrilateral, and presents at its anterior inferior angle a smooth oval facet, over Avhich the tendon of the Tibialis anticus muscle glides; rough in the rest of its extent, for the attachment of ligaments. The external surface is concaAre, presenting, along its superior and posterior borders, a narroAv surface for articulation with the middle cuneiform behind, and second metatarsal bone in 128 OSTEOLOGY. front; in the rest of its extent, it is rough for the attachment of ligaments, and prominent beloAV, where it forms part of the tuberosity. The anterior surface, reniform in shape, articulates Avith the metatarsal bone of the great toe. The posterior surface is triangular, concave, and articulates Avith the innermost and largest of the three facets on the anterior surface of the scaphoid. The inferior or plantar surface is rough, and presents a prominent tuberosity at its back part for the attachment of part of the tendon of the Tibialis posticus. It also gives attachment in front of this to part of the tendon of the Tibialis anticus. The superior surface is the narrow pointed end of the wedge, which is directed upwards and outwards; it is rough for the attachment of ligaments. To ascertain to which side it belongs, hold the bone so that its superior narrow edge looks upwards, and the long articular surface forwards ; the external surface, marked by its vertical and horizontal articular facets, will point to the side to Avhich it belongs. Articulations. With four bones : scaphoid, middle cuneiform, and first and second metatarsal bones. Attachment of Muscles. The Tibialis anticus and posticus. The Middle Cuneiform. The Middle Cuneiform, the smallest of the three, is of very regular Avedge-like form; the broad extremity being placed upwards, the narrow end downwards. It is situated betAveen the other two bones of the same name, and corresponds to the scaphoid behind, and the second metatarsal in front. The anterior surface, triangular in form, and narrower than the posterior, articu- lates with the base of the second metatarsal bone. The posterior surface, also triangular, articulates with the scaphoid. The internal surface presents an articular facet, running along the superior and posterior borders, for articulation with the internal cuneiform, and is rough beloAV for the attachment of ligaments. The external surface presents posteriorly a smooth facet for articulation with the external cuneiform bone. The superior surface forms the base of the wedge; it is quadrilateral, broader behind than in front, and rough for the attachment of ligaments. The inferior surface, pointed and tubercular, is also rough for liga- mentous attachment. To ascertain to Avhich foot the bone belongs, hold its superior or dorsal surface upAvards, the broadest edge being tOAvards the holder, and the smooth facet (limited to the posterior border) will point to the side to which it belongs. Articulations. With four bones : scaphoid, internal and external cuneiform, and second metatarsal bone. The External Cuneiform. The External Cuneiform, intermediate in size between the tAvo preceding, is of a very regular wedge-like form, the broad extremity being placed upAvards, the narrow end doAvmvards. It occupies the centre of the front roAv of the tarsus betAveen the middle cuneiform internally, the cuboid externally, the scaphoid behind, and the third metatarsal in front. It has six surfaces for examination. The anterior surface, triangular in form, articulates Avith the third metatarsal bone. The posterior surface articulates with the most external facet of the scaphoid, and is rough beloAV for the attachment of ligamentous fibres. The internal surface, pre- sents tAvo articular facets separated by a rough depression; the anterior one, situated at the superior angle of the bone, articulates with the outer side of the base of the second metatarsal bone; the posterior one skirts the posterior border, and articu- lates Avith the middle cuneiform; the rough depression betAveen the tAvo gives attachment to an interosseous ligament. The external surface also presents two articular facets, separated by a rough non-articular surface; the anterior facet, situated at the superior corner of the bone, is small, and articulates Avith the inner side of the base of the fourth metatarsal; the posterior, and larger one, articulate; METATARSAL BONES. 129 with the cuboid; the rough non-articular surface serves for the attachment of an interosseous ligament. The three facets for articulation with the three metatarsal bones are continuous Avith one another, and covered by a prolongation of the same cartilage; the facets for articulation Avith the middle cuneiform and scaphoid are also continuous, but that for articulation Avith the cuboid is usually separate and independent. The superior or dorsal surface, of an oblong form, is rough for the attachment of ligaments. The inferior or plantar surface is an obtuse rounded margin, and serves for the attachment of part of the tendon of the Tibialis posticus, some of the fibres of origin of the Flexor brevis policis, and ligaments. To ascertain to which side it belongs, hold the bone Avith the broad dorsal sur- face upAvards, the prolonged edge backAvards; the separate articular facet for the cuboid will point to the proper side. Articulations. With six bones ; the scaphoid, middle cuneiform, cuboid, and second, third, and fourth metatarsal bones. Attachment of Muscles. Part of Tibialis posticus, and Flexor brevis pollicis. The Metatarsal Bones. The Metatarsal bones are five in number; they are long bones, and subdivided into a shaft, and two extremities. The Shaft is prismoid in form, tapers gradually from the tarsal to the phalan- geal extremity, and is slightly curved longitudinally, so as to be concave beloAv, slightly convex above. The Posterior Extremity, or Base, is Avedge-shaped, articulating by its terminal surface with the tarsal bones, and by its lateral surfaces Avith the contiguous bones ; its dorsal and plantar surfaces being rough for the attachment of ligaments. The Anterior Extremity, or Head, presents a terminal rounded articular sur- face, oblong from above doAvmvards, and extending further backAvards below than above. Its sides are flattened, and presents a depression, surmounted by a tuber- cle, for ligamentous attachment. Its under surface is grooved in the middle line, for the passage of the Flexor tendon, and marked on each side by an articular eminence continuous Avith the terminal articular surface. Peculiar Metatarsal Bones. The First is remarkable for its great size, but is the shortest of all the meta- tarsal bones. The shaft is strong, and of well-marked prismoid form. The posterior extremity presents no lateral articular facets ; its terminal articular sur- face is of large size, of semilunar form, and its circumference grooved for the tarso-metatarsal ligaments; its inferior angle presents a rough oval prominence, for the insertion of the tendon of the Peroneus longus. The head is of large size ; on its plantar surface are tAvo grooved facets, over which glide sesamoid bones, separated by a smooth elevated ridge. The Second is the longest and largest of the remaining metatarsal bones; its posterior extremity being prolonged backwards, into the recess formed between the three cuneiform bones. Its tarsal extremity is broad above, narrow and rough beloAV. It presents four articular surfaces; one behind, of a triangular form, for articulation Avith the middle cuneiform; one at the upper part of its internal lateral surface, for articulation Avith the internal cuneiform; and tAvo on its external lateral surface, a superior and an inferior, separated by a rough depres- sion. Each articular surface is divided by a vertical ridge into tAvo parts; the anterior segment of each facet articulates Avith the third metatarsal; the two pos- terior (sometimes continuous) with the external cuneiform. The Third articulates behind, by means of a triangular smooth surface, with the external cuneiform: on its inner side, by tAvo facets, Avith the second meta- tarsal : and on its outer side, by a single facet, with the third metatarsal. This facet is of circular form, and situated at the upper angle of the base. 11 130 OSTEOLOGY. The Fourth is smaller in size than the preceding; its tarsal extremity presents a terminal quadrilateral surface, for articulation with the cuboid; a smooth facet on the inner side, divided by a ridge into an anterior portion for articulation with the third metatarsal, and a posterior portion for articulation with the external cuneiform ; on the outer side a single facet for articulation with the fifth metatarsal. The Fifth is recognized by the tubercular eminence on the outer side of its base ; it articulates behind, by a triangular surface cut obliquely from without inwards, with the cuboid, and internally Avith the fourth metatarsal. Articulations. Each bone articulates with the tarsal bones by one extremity, and by the other with the first row of phalanges. The number of tarsal bones with Avhich each metatarsal articulates is one for the first, three for the second, one for the third, two for the fourth, and one for the fifth. Attachment of Muscles. To the first metatarsal bone, three : part of the Tibialis anticus, Peroneus longus, and First dorsal interosseous. To the second, three: the Adductor pollicis, and First and Second dorsal interosseous. To the third, four: the Adductor pollicis, Second and Third dorsal interosseous, and First plantar. To the fourth, four: the Adductor pollicis, Third and Fourth dorsal, and Second plantar interosseous. To the fifth, five: the Peroneus brevis, Pero- neus tertius, Flexor brevis minimi digiti, Fourth dorsal, and Third plantar inter- osseous. Phalanges. The Phalanges of the foot, both in number and general arrangement, resemble those in the hand: there being two in the great toe, and three in each of the other toes. The phalanges of the first row resemble closely those of the hand. The shaft is compressed from side to side, convex above, concave below. The posterior extremity is concave; and the anterior extremity presents a trochlear articular surface, for articulation with the second phalanges. The phalanges of the second row are remarkably small and short, but rather broader than those of the first i*oav. The ungual phalanges in form resemble those of the fingers; but they are smaller, flattened from above downwards, presenting a broad base for articulation with the second row, and an expanded extremity for the support of the nail and end of the toe. Articulations. The first roAv with the metatarsal bones, and second phalanges; the second of the great toe with the first phalanx, and of the other toes with the first and third phalanges; the third Avith the second row. Attachment of Muscles. To the first phalanges. Great toe : innermost tendon of Extensor brevis digitorum, Abductor pollicis, Adductor pollicis, Flexor brevis pollicis, Transversus pedis. Second toe: First and Second dorsal interossei. Third toe : Third dorsal and First plantar interossei. Fourth toe : Fourth dor- sal and Second plantar interossei. Fifth toe: Flexor brevis minimi digiti, Abductor minimi digiti, and Third plantar interosseous. — Second phalanges, great toe : Extensor longus pollicis, Flexor longus pollicis. Other toes: Flexor brevis digitorum, one slip from the Extensor brevis digitorum and Extensor longus digitorum.—Third phalanges : two slips from the common tendon of the Extensor longus and Extensor brevis digitorum, and the Flexor longus digitorum. Development of the Foot. (Fig. 98.) The Tarsal bones are each developed by a single centre, excepting the os ealcis, which has an epiphysis for its posterior extremity. The centres make their appearance in the folloAving order: in the os ealcis, at the sixth month of foetal life; in the astragalus, about the seventh month ; in the cuboid, at the ninth month; external cuneiform, during the first year; internal cuneiform, in the third year; middle cuneiform, in the fourth year. The epiphysis for the posterior SESAMOID BONES. 131 tuberosity of the os ealcis appears at the tenth year, and unites with the rest of the bone soon after puberty. The Metatarsal bones are each developed by two centres: one for the shaft and one for the digital extremity in the four outer metatarsal; one for the shaft^ and one for the base in the metatarsal bone of the great toe. Ossification Fig. 98.—Plan of the Development of the Foot. unites afterputerty Tars us / Centre for eaeJi lo?ie txeev t Oil Calcis Metatarsus 2 Centres for each tone / for Shaft 1 for Digital Extremity cj-c/pt /.?? -Appears 6! " on all sides," apOptr;, "a joint"), or Mixed Articulation. In this form of articulation, the contiguous osseous surfaces are connected together by broad flattened discs of fibro-cartilage, which adhere to the ends of both bones, as in the articulation betAveen the bodies of the vertebrae, and first two pieces of the sternum; or the articulating surfaces are covered by fibro-cartilage, lined by a partial synovial membrane, and connected together by external ligaments, as in the sacro-iliac and pubic symphyses; both these forms being capable of limited motion in every direction. The former resemble the synarthrodial joints in the continuity of their surfaces, and absence of synovial sac; the latter, the diarthro- dial. These joints occasionally become obliterated in old age: this is frequently the case in the interpubic articulation, and occasionally in the intervertebral and sacro-iliac. 3. Diarthrosis. Movable Articulations. Diarthrosis (&«, "through," apOpov, "a joint"). This form of articulation includes the greater number of the joints of the body, mobility being their dis- tinguishing character. They are formed by the approximation of two contiguous bony surfaces, covered with cartilage, connected by ligaments, and having a syno- vial sac interposed. The varieties of joints in this class have been determined by the kind of motion permitted in each; they are four in number: Arthrodia, Enarthrosis, Ginglymus, Diarthrosis Rotatorius. # _ Arthrodia is that form of joint which admits of a gliding movement: it is formed by the approximation of plane surfaces, or one slightly concave, the other slightly convex, the amount of motion between them being limited by the liga- ments, or osseous processes, surrounding the articulation; as in the articular pro- cesses'of the vertebrae, temporo-maxillary, sterno and acromio-clavicular, inferior radio-ulnar, carpal, carpo-metacarpal, superior tibio-fibular, tarsal, and tarso-meta- tarsal articulations. . . ,,,.,. Enarthrosis is that form of joint which is capable of motion in all directions. It is formed by the reception of a globular head into a deep cup-like cavity (hence the name "ball and socket"), the parts being kept in apposition by a capsular ligament strengthened by accessory ligamentous bands, and the contiguous carti- laginous surfaces having a synovial sac interposed. Examples of this form of articulation are found in the hip and shoulder joints. _ # Ginghjmus, Hinge-joint (wV°S "a hinge"). In this form of joint, the articular surfaces are moulded to each other in such a manner as to permit motion only in one direction, forwards and backwards, the extent of motion at the same time being considerable. The articular surfaces are connected together by strong lateral ligaments, which form their chief bond of union. The most perfect forms of ginglymi arc the elbow and ankle : the knee is less perfect, as it allows a slight degree of rotation in certain positions of the limb : there are also the metatarso-phalangeal and phalangeal joints in the lower extremity, metacarpo- phalangeal and phalangeal joints in the upper extremity. _ Diarthrosis rotatorius (Lateral Ginglymus). Where the mobility is limited to rotation, the joint is formed by a pivot-like process turning within a ring, or the ring on a pivot, the ring being formed partly of bone, partly of ligament. In the articulation of the odontoid process of the axis with the atlas, the ring is formed in front by the anterior arch of the atlas; behind, by the transverse ligament:_ here the ring rotates around the odontoid process. In the superior radio-ulnar articula- tion the ring is formed partly by the lesser sigmoid cavity of the ulna ; in the rest of it's extent, by the orbicular ligament;. here, the neck of the radius rotates within the ring. SUBDIVISION INTO THREE CLASSES. 137 Subjoined, in a tabular form, are the names, distinctive characters, and examples of the different kinds of articulations. Dentata, having tooth-like processes. Interparietal su- ture. Serrata, having serrated edges, like the teeth of a saw. Interfrontal su- ture. Limbosa, having bevelled margins, and dentated pro- cesses. Occipito - parietal suture. Sutura vera (true), articulate < by indented bor ders. Synarthrosis, or im- movable joint. Sur- faces separated by fibrous membrane, no intervening synovial cavity, and immova- bly connected with each other. Example: bones of cranium and face (except lowrer jaw). Sutura. Arti- culation by pro- cesses and indent- ations interlocked together. Sutura notha (false), articulate .by rough surfaces. Squamosa, formed by thin bevelled mar- gins overlapping each other. Temporo - parietal sutures. Harmonia, formed by the apposition of contiguous rough surfaces. Intermaxillary su- ture. Schindylesis. Articulation formed by the reception of a thin plate of bone into a fissure of another. Rostrum of sphenoid with vomer. G-omphosis. An articulation formed by the insertion of a conical process into a socket. Tooth in socket. Amphiarthrosis, Mixed Articulation. Diarthrosis, Movable Joint. 1. Surfaces connected by fibro-cartilage, not separated by synovial membrane, and having limited motion. Bodies of vertebrae. 2. Surfaces connected by fibro-cartilage, lined by a partial synovial membrane. Sacro-iliac and pubic symphyses. Arthrodia. Gliding joint; articulation by plane surfaces, Avhich glide upon each other. As in sterno and acromio- clavicular articulations. Enarthrosis. Ball and socket joint; capable of motion in all directions. Articulation by a globular head received into a cup-like cavity. As in hip and shoulder joints. Ginglymus. Hinge joint; motion limited to one direction, forAvards and backwards. Articular surfaces fitted together so as to permit of movement in one plane. As in the elbow, ankle, and knee. Diarthrosis rotatorius. Articulation by a pivot process turning within a ring, or ring around a pivot. As in the superior radio-ulnar articulation, and atlo-axoid joint. 138 ARTICULATIONS. The Kinds of Moa'ement admitted in Joints. The movements admissible in joints may be divided into four kinds, glidin*-*- angular movement, circumduction, and rotation. Gliding movement is the most simple kind of motion that can take place in a joint, one surface gliding over another. This kind of movement is common to all movable joints; but in some, as in the articulation of the carpus and tarsus is the only motion permitted. This motion is not confined to plane surfaces, but may exist between any two contiguous surfaces, of Avhatever form, limited by the ligaments Avhich inclose the articulation. Angular movement occurs only betAveen the long bones, and may take place in four directions, forAvards or backAvards, constituting flexion and extension, or imvards and outwards, Avhich constitutes abduction and adduction. Flexion and extension are confined to the strictly ginglymoid or hinge joints. Abduction and adduction, combined Avith flexion and extension, are met Avith only in the most movable joints; as in the hip, shoulder, and thumb, and partially in the Avrist and ankle. Circumduction is that limited degree of motion Avhich takes place betAveen the head of a bone and its articular cavity, Avhilst the extremity and sides of a limb are made to circumscribe a conical space, the base of Avhich corresponds with the inferior extremity of the limb, the apex to the articular caArity; and is best seen in the shoulder and hip joints. Rotation is the movement of a bone upon its oivn axis, the bone retaining the same relative situation with respect to the adjacent parts; as in the articulation between the atlas and axis, where the odontoid process serves as a pivot around which the atlas turns; or in the rotation of the radius against the humerus, and also in the hip and shoulder. The articulations may be arranged into those of the trunk, those of the upper extremity, and those of the loAver extremity. ARTICULATIONS OF THE TRUNK. These may be divided into the following groups aIz. :— 1. Of the vertebral column. 7. Of the cartilages of the ribs with the 2. Of the atlas with the axis. sternum, and with each other. 3. Of the atlas with the occipital bone. 8. Of the sternum. 4. Of the axis Avith the occipital bone. 9. Of the vertebral column with the o. Of the lower jaAv. pelvis. 6. Of the ribs with the vertebras. 10. Of the pelvis. 1. Articulations of the Vertebral Column. The different segments of the vertebral column are connected together by ligaments, which admit of the same arrangement as the vertebrae themselves. They may be divided into five sets. 1. Those connecting the bodies of the vertebrae. 2. Those connecting the lamince. 3. Those connecting the articular processes. 4. The liga- ments connecting the spinous processes. 5. Those of the transverse processes. The articulations of the bodies of the vertebrae Avith each other forms a series of amphiarthrodial joints ; whilst those between the articular processes form a series of arthrodial joints. (1.) The Liuaments of the Bodies are Anterior Common Ligament. Posterior Common Ligament. Intervertebral Substance. The Anterior Common Ligament (Fig. 107) is a broad and strong band of ligamen- tous fibres, Avhich extend along the front surface of the bodies of the vertebrae, from the axis to the sacrum. It is broader below than above, and thicker in the dorsal than in the cervical or lumbar regions. It is attached, above, to the body of the axis by a pointed process, Avhich is connected Avith the tendon of origin of the Longus colli muscle; and, as it descends, is somewhat broader opposite the centre OF THE SPINE. 139 of the body of each vertebra, than opposite the intervertebral substance. It con- sists of dense longitudinal fibres, which are intimately adherent to the interverte- bral substance and prominent margins of the Arertebrae; but less closely with the centre of the bodies. In this situation the fibres are exceedingly thick, and serve to fill up the concaAlties on their front surface, and to make the anterior surface of the spine more even. This ligament is composed of several layers of fibres, which vary in their length, but are closely interlaced with each other. The most super- Fig. 99.—Vertical Section of two Vertebrae and their Ligaments, from the Lumbar Region. ficial or longest fibres extend between four or five vertebrae. A second subja- cent set extend between two or three vertebrae ; whilst a third set, the shortest and deepest, extend from one vertebra to the next. At the sides of the bodies, this ligament consists of a feAV short fibres, Avhich pass from one v&rtebra to the next, separated from the median portion by large oval apertures, for the passage of vessels. The Posterior Common Ligament is situated within the spinal canal, and extends along the posterior surface of the bodies of the vertebrae, from the body of the axis above, where it is continuous with the occipito-axoid ligament, to the sacrum beloAv. It is broader at the upper than at the lower part of the spine, and thicker in the dorsal than in the cervical or lumbar regions. In the situation of the intervertebral substance and contiguous margins of the vertebrae, where the ligament is more intimately adherent, it is broad, and presents a series of dentations with intervening concave margins; but it is narrow and thick over the centre of the bodies, from which it is separated by the venae basis vertebrce. This ligament is composed of smooth, shining, longitudinal fibres, denser and more com- pact than the anterior ligament, and composed of a superficial layer occupying the interval between three or four vertebrae, and of a deeper layer, which extends between one vertebra and the next adjacent to it. It is separated from the dura mater of the spinal cord by some loose filamentous tissue, very liable to serous infiltration. The Intervertebral Substance (Fig. 99) is a lenticular disc of fibro-cartilage, in- terposed betAveen the adjacent surfaces of the bodies of the vertebrse, from the axis to the base of the sacrum. These discs vary in shape, size, and thickness, in 140 ARTICULATIONS. different parts of the spine. In shape they accurately correspond with the surfaces of the bodies between Avhich they are placed, being oval in the cervical and lumbar regions, circular in the dorsal. Their size is greatest in the lumbar region. In thickness they vary not only in the different regions of the spine, but in different parts of the same region: thus, they are uniformly thick in the lumbar region • thickest in front in the cervical and lumbar regions Avhich are convex forwards and behind, to a slight extent in the dorsal region. They thus contribute, in a great measure, to the curvatures of the spine in the neck and loins; whilst the concavity of the dorsal region is chiefly due to the shape of the bodies of the vertebrae. The intervertebral discs form about one-fourth of the spinal column exclusive of the first tAvo vertebrae ; they are not equally distributed, however between the various bones; the dorsal portion of the spine having, in proportion to its length, a much smaller quantity than in the cervical and lumbar regions which necessarily gives to the latter parts greater pliancy and freedom of move- ment. The intervertebral discs are adherent, by their surfaces, to the adjacent parts of the bodies of the vertebrse ; and by their circumference are closely con- nected in front to the anterior, and behind to the posterior common ligament; whilst in the dorsal region they are connected laterally to the heads of those ribs Avhich articulate with two vertebrse, by means of the interarticular ligament; they consequently form part of the articular cavities in Avhich the heads of these bones are received. The intervertebral substance is composed, at its circumference, of laminae of fibrous tissue and fibro-cartilage; and at its centre of a soft, elastic, pulpy matter. The laminae are arranged concentrically one Avithin the other, with their edges turned towards the corresponding surfaces of the vertebrae, and consist of alternate plates of fibrous tissue and fibro-cartilage. These plates are not quite vertical in their direction, those near the circumference being curved outwards and closely approximated; whilst those nearest the centre curve in the opposite direction, and are someAvhat more widely separated. The fibres of Avhich each plate is com- posed are directed, for the most part, obliquely from above doAvmvards; the fibres of an adjacent plate have an exactly opposite arrangement, varying in their direc- tion in every layer; Avhilst in some feAV they are horizontal. This laminar arrangement belongs to about the outer half of each disc, the central part being occupied by a soft, pulpy, highly elastic substance, of a yellowish color, which rises up considerably aboAre the surrounding level, when the disc is divided hori- zontally. This substance presents no concentric arrangement, and consists of white fibrous* tissue, having interspersed cells of variable shape and size. The pulpy matter is separated from immediate contact with the vertebrse, by the inter- position of thin plates of cartilage. (2.) Ligaments connecting the Lamina. Ligamenta Subflava. The Ligamenta Subflava are interposed betAveen the laminse of the vertebrse, from the axis to the sacrum. They are most distinct when seen from the inner surface of the spine; Avhen vieAved from the outer surface, they appear short, being overlapped by the lamhne. Each ligament consists of two lateral portions, which commence on each side at the root of either articular process, and pass backAvards to the point Avhere the laminse converge to form the spinous process, where their margins are thickest, and separated by a slight interval, filled up with areolar tissue. These ligaments consist of yelloAv elastic tissue, the fibres of which, almost perpendicular in direction, are attached to the anterior surface of the margin of the lamina above, and to the posterior surface as Avell as to the margin of the lamina beloAV. In the cervical region, they are thin in texture, but very broad and long; they become thicker in the dorsal region; and in the lumbar acquire very considerable thickness. Their highly elastic property serves to preserve the upright posture, and to counteract the efforts of the Flexor muscles of the spine. These ligaments do not exist betAveen the occiput and atlas, or between the atlas and axh'. OF THE ATLAS WITH THE AXIS. 141 (3.) Ligaments connecting the Articular Processes. Capsular. Synovial Membranes. The Capsular Ligaments are thin and loose bags of ligamentous fibre attached to the contiguous margins of the articulating processes of each vertebra, through the greater part of their circumference, and completed internally by the liga- menta subflava. They are longer and more loose in the cervical than in the dorsal or lumbar regions. The capsular ligaments are lined on their inner surface by a delicate synovial membrane. (4.) Ligaments connecting the Spinous Processes. Interspinous. Supraspinous. The Interspinous Ligaments, thin and membranous, are interposed betAveen the spinous processes in the dorsal and lumbar regions. Each ligament extends from the-, root to near the summit of each spinous process, and connects together their adjacent margins. They are narrow and elongated in the dorsal region, broader, quadrilateral in form, and thicker in the lumbar region. The Supraspinous Ligament is a strong fibrous cord, which connects together the apices of the spinous processes from the seventh cervical to the spine of the sacrum. It is thicker and broader in the lumbar than in the dorsal region, and intimately blended, in both situations, with the neighboring aponeuroses. The most superficial fibres of this ligament connect three or four vertebrse ; those deeper seated pass between two or three vertebrse; whilst the deepest connect the con- tinuous extremities of neighboring vertebrse. (5.) Ligaments connecting the Transverse Processes. Intertransverse. The Intertransverse Ligaments consist of a few thin scattered fibres, interposed between the transverse processes. They are generally Avanting in the cervical region; in the dorsal, they are rounded cords; in the lumbar region, thin and membranous. The twTo upper vertebrse, the Atlas and Axis, are connected together by liga- ments distinct from those by which the rest are united. 2. Articulation of the Atlas avith the Axis. The articulation of the anterior arch of the atlas Avith the odontoid process forms a lateral ginglymoid joint, Avhilst that betAveen the articulating process of the two bones forms a double arthrodia. The ligaments of this articulation are the Tavo Anterior Atlo-axoid. Transverse. Posterior Atlo-axoid. Tavo Capsular. Four Synovial Membranes. Of the Two Anterior Atlo-axoid Ligaments (Fig. 100), the most superficial is a rounded cord, situated in the middle line, attached, above, to the tubercle on the anterior arch of the atlas; below, to the base of the odontoid process and body of the axis. The deeper ligament is a membranous layer, attached, above, to the lower border of the anterior arch of the atlas; below, to the base of the odontoid process and body of the axis. These ligaments are in relation, in front, Avith the Recti antici majores. The Posterior Atlo-axoid Ligament (Fig. 101), is a broad and thin membranous layer, attached, above, to the loAver border of the posterior arch of the atlas ; below, to the upper edge of the laminse of the axis. This ligament supplies the place of the ligamenta subflava, and is in relation, behind, Avith the Inferior oblique muscles. 142 ARTICULATIONS. The Transverse Ligament (Figs. 102,103) is a thick and strong ligamentous band which arches across the ring of the atlas, and serves to retain the odontoid process Fig. 100.—Occipito-atloid and Atlo-axoid Ligaments. Front View. C CAPSULAR LICT 1 SYNOVIAL M EMI ATLO- -AXOID f CAPSULAR LIGT & SYNOVIAL MEMERANB Fig. 101.—Occipito-atloid and Atlo-axoid Ligaments. Posterior View. AreJi forpaasagt ofVt.rtiiroU.A-ri kit. Can-teal Tu-Yi-e. in firm connection with its anterior arch. This ligament is flattened from before backwards, broader and thicker in the middle than at either extremity, and firmly OF THE ATLAS WITH THE OCCIPITAL BONE. 143 attached on each side of the atlas to a small tubercle on the inner surface of each of its lateral masses. As it crosses the odontoid process, a small fasciculus is derived from its upper and lower borders; the former, passing upwards to be inserted into the ba- silar process of the Fig. 102.—Articulation between Odontoid Process and Atlas. occipital bone; the latter, downwards, to be attached to the root of the odontoid process: hence this ligament has received the name of cruci- form. The transverse ligament divides the ring of the atlas into tAvo unequal parts; of these, the poste- rior and larger serves for the transmission of the cord and its membranes; the anterior and smaller serving to retain the odontoid process in its position. The lower border of the space formed between the atlas and transverse ligament being smaller than the upper (on account of the transverse ligament embracing firmly the narroAv neck of the odontoid process), while the central part of the odontoid process is larger than its base; this process is still retained in firm connection Avith the anterior arch when all the other liga- ments have been divided. The Capsular Ligaments are two thin and loose capsules, connecting the articular surfaces of the atlas and axis, the fibres being strongest on the anterior and external part of the articulation. There are four Synovial Membranes in this articulation. One lining the inner surface of each of the capsular ligaments; one betAveen the anterior surface of the odontoid process and anterior arch of the atlas; and one between the poste- rior surface of the odontoid process and the transverse ligament. This synovial membrane often communicates with those betAveen the condyles of the occipital bone and the articular surfaces of the atlas. Actions. This joint is capable of great mobility, and allows the rotation of the atlas, and, Avith it, of the cranium upon the axis, the extent of rotation being limited by means of the odontoid ligaments. Articulation of the Spine with the Cranium. The ligaments connecting the spine with the cranium may be divided into twro sets: those connecting the occipital bone with'the atlas; those connecting the occipital bone with the axis. 3. Articulation of the Atlas avith the Occipital Bone. This articulation is a double arthrodia. Its ligaments are the Tavo Anterior Occipito-atloid. Posterior Occipito-atloid. Two Lateral Occipito-atloid. Two Capsular and Synovial Membranes. Of the Two Anterior Ligaments (Fig. 100), the most superficial is a strong, narroAv, rounded cord, attached, above, to the basilar process of the occiput; beloAv, to the tubercle on the anterior arch of the atlas: the deeper ligament is a broad and thin membranous layer, Avhich passes betAveen the anterior margin of the foramen magnum above, and the whole length of the upper border of the anterior arch of the atlas beloAv. This ligament is in relation, in front, with the Recti antici minores; behind, with the odontoid ligaments. 144 ARTICULATIONS. The Posterior Occipito-atloid Ligament (Fig. 101) is a very broad but thin mem- branous lamina, intimately blended Avith the dura mater. It is connected, above, to the posterior margin of the foramen magnum; below, to the central part of the upper border of the posterior arch of the atlas. This ligament is incomplete at each side, and forms, with the superior intervertebral notches, an opening for the passage of the Arertebral artery and suboccipital nerve. It is in relation, behind, with the Recti postici minores and Obliqui superiores; in front, with the dura mater of the spinal canal, to Avhich it is intimately adherent. The Lateral Ligaments are strong bands of fibres, directed obliquely upwards and inAvards, attached, above, to the jugular process of the occipital bone; below, to the base of the transverse process of the atlas. The Capsular Ligaments surround the condyles of the occipital bone, and con- nect them Avith the articular surfaces of the atlas; they consist of thin and loose capsules, Avhich inclose the synovial membrane of this articulation. The synovial membranes between the occipital bone and atlas communicate occasionally with that between the posterior surface of the odontoid process and transverse liga- ment. Actions. The movements permitted in this joint are flexion and extension, Avhich give rise to the ordinary forward or backward nodding of the head, besides slight lateral motion to one or the other side. When either of these actions is carried beyond a slight extent, the whole of the cervical portion of the spine assists in its production. 4. Articulation of the Axis with the Occipital Bone. Occipito-axoid. Three Odontoid. To expose the ligaments, the spinal canal should be laid open by removing the posterior arch of the atlas, the laminse and spinous process of the axis, and that portion of the occipital bone behind the foramen magnum, as seen in Fig. 103. The Occipito-axoid Ligament (Apparatus ligamentosus colli) is situated at the Fig. 103.—Occipito-axoid and Atlo-axoid Ligaments. Posterior View. TEMPORO-MAXILLARY. 145 upper part of the front surface of the spinal canal. It is an exceedingly broad and strong ligamentous band, which covers the odontoid process and its ligaments, and appears to be a prolongation upwards of the posterior common ligaments of the spine. It is attached, below to the posterior surface of the body of the axis, and becoming broader and expanded as it ascends, is inserted into the basilar groove of the occipital bone, in front of the foramen magnum. Relations. By its anterior surface, it is intimately connected Avith the transverse ligament; by its posterior surface Avith the dura mater. By dividing this ligament transversely across, and turning its ends aside, the transverse and odontoid liga- ments are exposed. The Odontoid 01^ Check Ligaments are strong rounded fibrous cords, which arise one on either side of the apex of the odontoid process, and passing obliquely upwards and outAvards, are inserted into the rough depressions on the inner side of the condyles of the occipital bone. In the triangular interval left betAveen these ligaments and the margin of the foramen magnum, a third strong ligamentous band (ligamentum suspensorium) may be seen, Avhich passes almost perpendicularly from the apex of the odontoid process to the anterior margin of the foramen, being intimately blended with the anterior occipito-atloid ligament. Actions. The odontoid ligaments serve to limit the extent to which rotation of the cranium may be carried ; hence they have received the name of check ligaments. 5. Temporo-maxillary Articulation. This articulation is a double arthrodia. The parts entering into its formation are, on each side, the anterior part of the glenoid cavity of the temporal bone and the eminentia articularis above ; with the condyle of the lower jaAv beloAv. The ligaments are the folloAving. External Lateral. Capsular. -Internal Lateral. Interarticular Fibro-cartilage. Stylo-maxillary. Two Synovial Membranes. Fig. 104.—Temporo-maxillary Articulation. External View. 1n fe r i o r Maxilla 12 146 ARTICULATIONS. The External Lateral Ligament (Fig. 104) is a short, thin, and narrow fasciculus, attached above to the outer surface of the zygoma and to the rough tubercle on its lower border; below, to the outer surface and posterior border of the neck of the lower jaw. This ligament is a little broader above than below; its fibres are placed parallel with one another, and directed obliquely downwards and backwards. Externally, it is covered by the parotid gland and by the integument. Internally, it is in relation with the interarticular fibro-cartilage and the synovial membranes. The Internal Lateral Ligament (Fig. 105) is a long, thin, and loose band, attached above by its narrow extremity to the spinous process of the sphenoid bone, and J becoming broader as Fig. 105.—Temporo-maxillary Articulation. it descends, is insert- Internal View. ed into the inner margin of the dental foramen. Its outer surface is in relation above Avith the Exter- nal pterygoid mus- cle ; lower doAvn it is separated from tbe neck of the condyle by the internal max- illary artery; and still more inferiorly the inferior dental vessels and nerve separate it from the ramus of the jaw. Internally it is in re- lation Avith the Inter- nal pterygoid. The Stylo-maxil- lary Ligament is a thin aponeurotic cord, which extends from near the apex of the styloid process of the temporal bone, to the angle and poste- rior border of the ramus of the lower jaw, between the Masseter and Internal pterygoid muscles. This ligament separates the parotid from the submaxillary gland^ and has attached to its inner side part of the fibres of origin of the Stylo- glossus muscle. Although usually classed among the ligaments of the jaw, it can only be considered as an accessory in the articulation. _ The Capsular Ligament consists of a thin and loose ligamentous capsule, attached above to the circumference of the glenoid cavity and the articular surface immedi- ately in front: below, to the neck of the condyle of the lower jaw. _ It consists of a few thin scattered fibres, and can hardly be considered as a distinct ligament; it is thickest at the back part of the articulation. The Interarticular Fibro-Cartilage (Fig. 106) is a thin plate of a transversely oval form, placed horizontally between the condyle of the jaw and the glenoid cavity. Its upper surface is concave from before backAvards, and a little convex transversely, to accommodate itself to the form of the glenoid cavity. Its under surface, where it is in contact with the condyle, is concave. Its circumference is connected externally to the external lateral ligament; internally, to the capsular ligament: and in front, to the tendon of the External pterygoid muscle. It is thicker at its circumference, especially behind, than at its centre, whereat is some- times perforated. The fibres of which it is composed have a concentric arrange- ment, more apparent at the circumference than at the centre. Its surfaces are smooth, and divide the joint into two cavities, each of which is furnished -with COSTO-VERTEBRAL. 147 Fig. 106.—Vertical Section of Temporo-maxillary Articulation. a separate synovial membrane. When the fibro-cartilage is perforated, the syno- vial membranes are continuous with one another. The Synovial Mem- branes, two in number, are placed one above, and the other beloAV the fibro-cartilage. The upper one, the larger and looser of the tAvo, after lining the cartilage covering the glenoid caArity and eminentia articularis, is continued over the upper surface of the fibro-cartilage. The loAver one is inter- posed betAveen the un- der surface of the fibro-cartilage and the condyle of the jaAv, being prolonged downwards a little further behind than in front. Actions. The moArements permitted in this articulation are very extensive. Thus the jaAv may be depressed or elevated, or it may be carried forAvards or backAvards, or from side to side. It is by the alternation of these movements performed in suc- cession, that a kind of fotatory movement of the lower jaAv upon the upper takes place, Avhich materially assists in the mastication of the food. If the movement of depression is carried only to a slight extent, the condyles remain in the glenoid cavities, their anterior part descending only to a slight extent; but if depression is considerable, the condyles glide from the glenoid fossae on to the eminentia articularis, carrying with them the interarticular fibro-cartilages. When the jaAv is elevated, the condyles and fibro-cartilages are carried backAvards into their original position. When the jaAv is carried forAvards or backAvards, a horizontal gliding movement of the fibro-cartilages and condyles upon the glenoid cavities takes place in the antero-posterior direction ; Avhilst in the movement from side to side, this occurs in the lateral direction. 6. Articulation of the Ribs with the Vertebra. The articulation of the ribs Avith the vertebral column, may be divided into two sets. 1. Those which connect the heads of the ribs with the bodies of the vertebrse. 2. Those which connect the neck and tubercle of the ribs with the transverse processes. (1.) Articulation between the Heads of the Ribs and the Bodies of the Vertebra. These form a series of angular ginglymoid joints, connected together by the following ligaments :— Anterior Costo-vertebral or Stellate. Capsular. Interarticular. Two Synovial Membranes. The Anterior Costo-vertebral or Stellate Ligament (Fig. 107) connects the ante- rior part of the head of each rib, with the sides of the bodies of the vertebrse, and the intervening intervertebral disc. It consists of three flat bundles _ of liga- mentous fibres, which radiate from the anterior part of the head of the rib. The superior fasciculus passes upAvards to be connected Avith the body of the vertebra above; the inferior one descends to the body of the vertebra below ; and the middle one, the smallest and least distinct, passes horizontally inAvards to be attached to the intervertebral substance. 148 ARTICULATIONS. llelutions. In front with the thoracic ganglia of the sympathetic, the pleura, and on the right side, the vena azygos major ; behind, with the interarticular liga- ment and synovial membranes. In the first rib, which articulates Avith a single vertebra only, this ligament does not present a dis- Fig. 107.—Costo-vertebral and Costo-transverse Articulations. tin(jt division into three Anterior A iew. r ■ ■.. ., fasciculi; its superior fibres, however, pass to be attached to the body of the last cervical ver- tebra, as well as to that of the vertebra with Avhich the rib articu- lates. In the eleventh and tAvelfth ribs, which also articulate with a single vertebra, the same division does not exist, but the superior fibres of the ligament, in each case, are con- nected with the verte- ' bra above, as well as that with which the ribs articulate. The Capsular Liga- ment is a thin and loose ligamentous bag, Avhich surrounds the joint betAveen the head of the rib and the articular cavity formed by the junction of the vertebrse. It is very thin, firmly connected with the anterior ligament, and most distinct at the upper and loAver parts of the articulation. The Interarticular Ligament is situated in the interior of the articulation. It consists of a short band of fibres, flattened from above doAvmvards, attached by one extremity to the sharp crest on the head of the rib, and by the other to the inter- vertebral disc. It divides the joint into tAvo cavities, Avhich have no communica- tion with one another, and are each lined by a separate synovial membrane. In the first, eleventh, and tAvelfth ribs, the interarticular ligament does not exist, consequently there is but one synovial membrane. Actions. The movements permitted in these articulations are limited to elevation, depression, and slightly forAvards and backAvards. This movement varies, however, very much in its extent in different ribs. The first rib is almost entirely immov- able, excepting in strong and violent inspirations. The movement of the second rib is also not very extensive. In the other ribs, their mobility increases succes- sively to the two last, which are very movable. The ribs are generally more movable in the female than in the male. Lower Synovial (2.) Articulation betaveen the Neck and Tubercle of the Ribs avith the Transverse Processes. The ligaments connecting these parts are— Anterior Costo-transverse. Middle Costo-transverse (Interosseous). Posterior Costo-transverse. Capsular and Synovial Membrane. The Anterior Costo-transverse Ligament (Fig. 108), is a broad and strong COSTO-TRANSVERSE. 149 band of fibres, attached beloAv to the sharp crest on the upper border of the neck of each rib, and passing obliquely upwards and outwards, to the lower border of the transverse process immediately above. It is broader below than above broader and thinner between the lower ribs than between the upper, and more distinct in front than behind. This ligament is in relation, in front, with the intercostal vessels and nerves; behind, with the Longissimus dorsi. Its internal Fig 108.—Costo-transverse Articulation. Seen from above. border completes an aperture formed between it and the articular processes through Avhich pass the posterior branches of the intercostal vessels and nerve. Its external border is continuous Avith a thin aponeurosis, Avhich covers the External intercostal muscle. The first and last ribs have no anterior costo-transverse ligament. The Middle Costo-transverse or Interosseous Ligament consists of short, but strong fibres, which pass betAveen the rough surface on the posterior part of the neck of each rib, and the anterior surface of the adjacent transverse process. In order fully to expose this ligament, a horizontal section should be made across the transverse process and corresponding part of the rib; or the rib may be forcibly separated from the transverse process, and its fibres torn asunder. In the eleventh and twelfth ribs, this ligament is quite rudimentary. The Posterior Costo-transverse Ligament is a short, but thick and strong fasciculus, Avhich passes obliquely from the summit of the transverse process to the rough non-articular portion of the tubercle of the rib. This ligament is shorter and more oblique in the upper, than in the lower ribs. Those correspond- ing to the superior ribs ascend, and those of the inferior ones slightly descend. In the eleventh and twelfth ribs, this ligament is Avanting. The articular portion of the tubercle of the rib, and adjacent transverse process, form an arthrodial joint, provided with a thin capsular ligament attached to the circumference of the articulating surfaces, and inclosing a small sinwvial membrane. In the eleventh and twelfth ribs, this articulation is wanting. Actions. The movement permitted in these joints, is limited to a slight gliding motion of the articular surfaces one upon the other. 150 ARTICULATIONS. 7. Articulation of the Cartilages of the Ribs avith the Sternu.ai. The articulations of the cartilages of the true ribs Avith the sternum are arthro- dial joints. The ligaments connecting them are— Anterior Costo-sternal. Posterior Costo-sternal. Capsular. Synovial Membranes. The Anterior Costo-sternal Ligament (Fig. 109) is a broad and thin membranous Fig. 109.—Costo-sternal, Costo-xiphoid, and Intercostal Articulations. Anterior View. TAo synovidl cavttecs ex-poseel by n vertecnl section of tlie Sternum Ic Cartilages ntnueous vfilh Sternum, I NTER-ARTrCU LAft LIC! two Sitnoi/ia.i memiranes Single Synow'al Membrane band that radiates from the inner extremity of the cartilages of the true ribs, to the anterior surface of the sternum. It is composed of fasciculi, which pass in differ- COSTO-STERNAL, COSTO-XIPHOID, AND INTERCOSTAL. 151 ent directions. The superior fasciculi ascend obliquely, the inferior pass obliquely downwards, and the middle fasciculi horizontally. The superficial fibres of this ligament are the longest; they intermingle Avith the fibres of the ligaments above and beneath them, with those of the opposite side, and Avith the tendinous fibres of origin of the Pectoralis major ; forming a thick fibrous membrane, Avhich covers the surface of the sternum, but is more distinct at the lower than at the upper part. The Posterior Costo-sternal Ligament, less thick and distinct than the ante- rior, is composed of fibres Avhich radiate from the posterior surface of the sternal end of the cartilages of the true ribs, to the posterior surface of the sternum, becoming blended Avith the periosteum. The Capsular Ligament surrounds the joints formed betAveen the cartilages of the true ribs and the sternum. It is very thin, intimately blended with the anterior and posterior ligaments, and strengthened at the upper and lower part of the articulation by a few fibres, which pass from the cartilage to the side of the sternum. These ligaments protect the synovial membranes. Synovial Membranes. The cartilage of the first rib is directly continuous Avith the sternum, the synovial membrane being absent. The cartilage of the second rib articulates Avith the sternum by means of an interarticular ligament, attached by one extremity to the ridge Avhich separates the tAvo articular facets of the cartilage of the second rib, and by the other extremity to the cartilage^ which unites the first and second pieces of the sternum. This articulation is provided with two synovial membranes. That of the third rib has also two synovial mem- branes ; and that of the fourth, fifth, sixth, and seventh, each a single synovial membrane. These synovial membranes may be demonstrated by removing a thin section from the anterior surface of the sternum and cartilages, as seen in the figure. After middle life, the articular surfaces lose their polish, become rough- ened, and the synovial membranes appear to be Avanting. In old age, the articu- lations do not exist, the cartilages of most of the ribs becoming firmly united to the sternum. The cartilage of the seventh rib, and occasionally also that of the sixth, is connected to the anterior surface of the ensiform appendix, by a band of ligamentous fibres, Avhich varies in length and breadth in different subjects. It is called the costo-xiphoid ligament. Actions. The movements Avhich are permitted in the costo-sternal articulations, are limited to elevation and depression; and these only to a slight extent. Articulation of the Cartilages of the Ribs with each other. The cartilages of the sixth, seventh, and eighth ribs articulate, by their loAver borders, Avith the corresponding margin of the adjoining cartilages, by means of a small, smooth, oblong-shaped facet. Each articulation has a perfect synovial membrane inclosed in a thin capsular ligament, strengthened externally and internally by some ligamentous fibres (intercostal ligaments), which pass from one cartilage to the other, and Avhich are intimately united to the perichondrium. Sometimes the cartilage of the fifth rib, more rarely that of the ninth, articulate, by their lower borders, with the corresponding cartilages by small oval facets ; more frequently they are connected together by a feAV ligamentous fibres. Occa- sionally, the articular surfaces above mentioned are found wanting. Articulations of the Ribs avith their Cartilages. The outer extremity of each costal cartilage is received into a depression in the sternal end of the ribs, and held together by the periosteum. 8. Ligaments of the Sternum. The first and second pieces of the Sternum are united by a layer of cartilage which rarely ossifies, except at an advanced period of life. These two segments are connected by an anterior and posterior ligament. 152 ARTICULATIONS. The anterior sternal ligament consists of a layer of fibres, having a longi- tudinal direction ; they blend Avith the fibres of the anterior costo-sternal lini- ments on both sides, and Avith the aponeurosis of origin of the Pectoralis major. This ligament is rough, irregular, and much thicker at the lower than at the upper part of this bone. The posterior sternal ligament is disposed in a somewhat similar manner on the posterior surface of the articulation. 9. Articulation of the Pelvis avith the Spine. The ligaments connecting the last lumbar vertebra with the sacrum, are similar to those Avhich connect the segments of the spine Avith each other, viz.: 1. The con- tinuation downwards of the anterior and posterior common ligaments. 2. The intervertebral substance connecting the flattened oval surfaces of the tAvo bones, thus forming an amphiarthrodial joint. •]. Ligamenta subflava, connecting the arch of the last lumbar vertebra with the posterior border of the sacral canal. 4. Capsular ligaments and synovial membranes connecting the articulating pro- Fig. 110.—Articulations of Pelvis and Hip. Anterior View. cesses and forming a double arthrodia 5. Interspinous and supraspinous liga- ments. The two proper ligaments connecting the pelvis Avith the spine are the lumbo- sacral and lumbo-iliac. The Land>o-sacral Ligament (Fig. 110) is a short, thick, triangular fasciculus, connected above to the lower and front part of the transverse process of the last lumbar vertebra, and passing obliquely outAvards, is attached below to the lateral surface of the base of the sacrum ; becoming blended Avith the anterior sacro-iliac ligament. This ligament is in relation anteriorly Avith the Psoas muscle. The Lumbo-iliac Ligament (Fig. 110) passes horizontally outAvards from the SACRO-ILIAC. 153 apex of the transverse process of the last lumbar vertebra, to that portion of the crest of the ilium immediately in front of the sacro-iliac articulation. It is of a triangular form, thick and narrow internally, broad and thinner externally; and is in relation, in front, Avith the Psoas muscle; behind, Avith the muscles occupying the vertebral groove; above, Avith the Quadratus lumborum. 10. Articulations of the Pelvis. The Ligaments connecting the bones of the pelvis Avith each other may be divided into four groups. 1. Those connecting the sacrum and ilium. 2. Those passing betAveen the sacrum and ischium. 3. Those connecting the sacrum and coccyx. 4. Those betAveen the tAvo pubic bones. (1.) Articulation of the Sacrum and Ilium. The sacro-iliac articulation is an amphiarthrodial joint, formed between the lateral surfaces of the sacrum and ilium. The anterior or auricular portion of the articular surfaces is covered Avith a thin plate of cartilage, thicker on the sacrum than On the ilium. The surfaces of these cartilages in the adult are rough and irregular, and separated from one another by a soft yellow pulpy substance. At an early period of life, occasionally in the adult, and in the female during preg- Fig. 111.—Articulations of Pelvis and Hip. Posterior View nancy, they are smooth and lined by a delicate synovial membrane. The ligaments connecting these surfaces are the anterior and posterior sacro-iliac. The Anterior Sacro-iliac Ligament consists of numerous thin ligamentous bands, which connect the anterior surfaces of the sacrum and ilium. The Posterior Sacro-iliac (Fig. Ill) is a strong interosseous ligament, situated in the deep depression betAveen the sacrum and ilium behind, and forming the 154 ARTICULATIONS. chief bond of connection between these bones. It consists of numerous strong fasciculi, Avhicli pass betAveen the bones in various directions. Three of these are of large size; the two superior, nearly horizontal in direction, arise from the first and second transverse tubercles on the posterior surface of the sacrum, and are inserted into the rough uneven surface at the posterior part of the inner surface of the ilium. The third fasciculus, oblique in direction, is attached by one extre- mity to the third or fourth transverse tubercle on the posterior surface of the sacrum, and by the other to the posterior superior spine of the ilium; it is some- times called the oblique sacro-iliac ligament. (2.) Articulation of the Sacrum and Ischium. The Great Sacro-sciatic (Posterior). The Lesser Sacro-sciatic (Anterior). The Great or Posterior Sacro-sciatic Ligament is situated at the posterior and inferior part of the pelvis. It is thin, flat, and triangular in form ; narroAver in the middle than at the extremities ; attached by its broad base to the posterior inferior spine of the ilium, to the third and fourth transverse tubercles on the sacrum, and to the loAver part of the lateral margin of that bone and the coccyx; passing obliquely downwards, outAvards, and forAvards, it becomes narroAv and thick ; and at its insertion into the inner margin of the tuberosity^, it increases in breadth, and is prolonged forAvards along the inner margin of the ramus forming the falciform ligament. The free concave edge of this ligament has attached to it the obturator fascia, Avith Avhich it forms a kind of groove, protecting the internal pudic vessels and nerve. One of its surfaces is turned tOAvavds the peri- nseum, the other towards the Obturator internus muscle. The posterior surface of this ligament gives origin, by its Avhole extent, to fibres of the Glutseus maximus. Its anterior surface is united to the lesser sacro- sciatic ligament. Its superior border forms the Ioavoi boundary of the lesser sacro-sciatic foramen. Its lower border forms part of the boundary of the peri- nseum. This ligament is pierced by the coccygeal branch of the sciatic artery. The Lesser or Anterior Sacro-sciatic Ligament, much shorter and smaller than the preceding, is thin, triangular in form, attached by its apex to the spine of the ischium, and internally, by its broad base, to the lateral margins of the sacrum and coccyx, anterior to the attachment of the great sacro-sciatic ligament, with Avhich its fibres are intermingled. It is in relation, anteriorly, with the Coccygeus muscle ; posteriorly, it is covered by the posterior ligament, and crossed by the pudic vessels and nerves. Its superior border forms the loAver boundary of the great sacro-sciatic foramen, its inferior border, part of the lesser sacro-sciatic foramen. These two ligaments convert the sacro-sciatic notches into foramina. The superior or larger sacro-sciatic foramen is bounded, in front and above, by the posterior border of the os innominatum ; behind, by the great sacro-sciatic liga- ment ; and below, by the lesser ligament. It is partially filled up, in the recent state, by the Pyriformis muscle. Above this muscle, "the gluteal vessels and nerve emerge from the pelvis; and beloAv it, the ischiatic vessels and nerves, the internal pudic vessels and nerve, and the nerve to the Obturator internus. The inferior or smaller sacro-sciatic foramen is bounded, in front, by the tuber ischii; above, by the spine and lesser ligament; behind, bv the greater ligament. It transmits the tendon of the Obturator internus muscle, its nerve, and the pudic vessels and nerve. (3.) Articulation of the Sacrum and Coccyx. This articulation is an amphiarthrodial joint, formed between the oval surface on the summit of the sacrum, and the base' of the coccyx. It is analogous to the SACRO-COCCYGEAL. 155 joints betAveen the bodies of the vertebrse, and is connected by similar ligaments. They are the Anterior Sacro-coccygeal. Posterior Sacro-coccygeal. Interarticular Fibro-cartilage. The Anterior Sacro-coccygeal Ligament consists of a few irregular fibres, Avhich descend from the anterior surface of the sacrum to the front of the coccyx^ becoming blended Avith the periosteum. The Posterior Sacro-coccygeal Ligament is a flat band of ligamentous fibres, of a pearly tint, Avhich arises from the margin of the lower orifice of the sacral canal, and descends to be inserted into the posterior surface of the coccyx. This ligament completes the lower and back part of the sacral canal. Its superficial fibres are much longer than the deep-seated; the latter extend from the apex of the sacrum to the upper cornua of the coccyx. Anteriorly, it is in relation with the arach- noid membrane of the sacral canal, a portion of the sacrum, and almost the whole of the posterior surface of the coccyx: posteriorly, Avith some aponeurotic fibres from the Glutseus maximus. An Interarticular Fibro-cartilage is interposed between the contiguous sur- faces of the sacrum and coccyx; it differs from that interposed between the bodies of the vertebrse, in being thinner, and its central part more firm in texture. It is somewhat thicker in front and behind, than at the sides. Occasionally a synovial membrane is found where the coccyx is freely movable, Avhich is more especially the case during pregnancy. The different segments of the coccyx are connected together by an extension downwards of the anterior and posterior sacro-coccygeal ligaments, a thin annular disc of fibro-cartilage being interposed between each of the bones. In the adult male, all the pieces become ossified ; but in the female, this does not commonly occur until a later period of life. The separate segments of the coccyx are first united, and at a more advanced age the joint between the sacrum and the coccyx. Actions. The movements Avhich take place between the sacrum and coccyx, and between the different pieces of the latter bone, are slightly forwards and back- wards : they are very limited. Their mobility increases during pregnancy. (4.) Articulation of the Pubes. The articulation betAveen the ossa pubis is an ampbiarthrodial joint, formed by the junction of the tAvo oval surfaces Avhich have received the name of the sym- physis. The ligaments of this articulation are the Anterior Pubic. Posterior Pubic. Superior Pubic. Subpubic. Interarticular Fibro-cartilage. The Anterior Pubic Ligament consists of several superimposed layers, which pass across the anterior surface of the articulation. The superficial fibres pass obliquely from one bone to the other, decussating and forming an interlacement with the fibres of the aponeurosis of the External oblique muscle. The deep fibres pass transversely across the symphysis, and are blended with the inter- articular fibro-cartilage. The Posterior Pubic Ligament consists of a few thin, scattered fibres, Avhich unite the tivo pubic bones posteriorly. The Superior Pubic Ligament is a band of fibres, Avhich connects together the two pubic bones superiorly. The Subpubic Ligament is a thick, triangular arch of ligamentous fibres, con- necting together the tAvo pubic bones beloAv, and forming the upper boundary of the pubic arch. Above, it is blended with the interarticular fibro-cartilage ; laterally, with' the rami of the pubes. Its fibres are of a yellowish color, closely connected, and have an arched direction. 156 ARTICULATIONS. The Interarticular Fibro-cartilage consists of tAvo OAral-shaped plates, one coverin-T the surface of each symphysis pubis. They vary in thickness in different subjects, and project somewhat beyond the level of the bones, espe- cially behind. The outer surface of each is firmly connected to the bone by a series of nipple-like processes, Avhich accurately fit Avithin corresponding depres- sions on the osseous surface. Their opposed surfaces are connected, in the greater part of their extent, by an intermediate fibrous elastic tissue ; and by their cir- cumference to the various ligaments surrounding the joint. An interspace is left betAveen the tAvo plates at the upper and back part of the articulation, where the Fig. 112.—Vertical Section of the Symphysis Pubis. Made near its Posterior Surface. Tiifo Fihro-Cartilaejirwusplates fnUr-mediate elastic tissue Synovial caiitt/ at tipper tc bach pay fibrous tissue is deficient, and the surface of the fibro-cartilage lined by epithelium. This space is found at all periods of life, both in the male and female; but it is larger in the latter, especially during pregnancy and after parturition. It is most frequently limited to the upper and back part of the joint; but it occasion- ally reaches to the front, and may extend the entire length of the cartilages. This structure may be easily demonstrated, by making a vertical section of the symphysis pubis near its posterior surface. * The Obturator Ligament is a dense membranous layer, consisting of fibres which interlace in various directions. It is attached to the circumference of the obturator foramen, which it closes completely, except at its upper and outer part, where a small oval canal is left for the passage of the obturator vessels and nerve. It is in relation, in front, with the Obturator externus ; behind, with the Obtura- tor internus; both of Avhich muscles are in part attached to it. ARTICULATIONS OF THE UPPER EXTREMITY. The articulations of the Upper Extremity may be arranged into the following groups: 1. Sterno-clavicular articulation. 2. Scapulo-clavicular articulation. 3. Ligaments of the scapula. 4. Shoulder joint. 5. Elbow joint. 6. Radio- ulnar°articulation. 7. Wrist joint. 8. Articulation of the Carpal bones. 9. Carpo-metacarpal articulation. 10. Metacarpophalangeal articulation. 11. Arti- culation of the Phalanges. 1. Sternoclavicular Articulation. The Sterno-clavicular is an arthrodial joint. The parts entering into its formation are the sternal end of the clavicle, the upper and lateral part of the STERNO-CLAVICULAR. 157 first piece of the. sternum, and the cartilage of the first rib. The articular surface of the clavicle is much longer than that of the sternum, and invested with a Fig. 113.—Sterno-clavicular Articulation. Anterior View. layer of cartilage, which is considerably thicker than that on the latter bone. The ligaments of this joint are the Anterior Sterno-clavicular. Costo-clavicular (rhomboid). Posterior Sterno-clavicular. Interarticular Fibro-cartilage. Interclavicular. Two Synovial Membranes. The Anterior Sterno-clavicidar Ligament is a broad band of ligamentous fibres, which covers the anterior surface of the articulation, being attached, above, to the upper and front part of the inner extremity of the clavicle ; and, passing obliquely dowmvards and inAvards, is attached, below, to the front and upper part of the first piece of the sternum. This ligament is covered anteriorly by the sternal portion of the Sterno-cleido-mastoid and the integument; behind, it is in relation AAuth the interarticular fibro-cartilage and the tAvo synovial membranes. The Posterior Sterno-clavicular Ligament is a broad band of fibres, which covers the posterior surface of the articulation, being attached, above, to the pos- terior part of the inner extremity of the clavicle ; and, passing obliquely down- wards and inAvards, to be connected, beloAv, to the posterior and upper part of the sternum. It is in relation, in front, with the interarticular fibro-cartilage and synovial membranes; behind, Avith the Sterno-hyoid and Sterno-thyroid muscles. The Interclavicular Ligament is a flattened ligamentous band, which varies considerably in form and size in different individuals; it passes from the superior part of the inner extremity of one clavicle to the other, and is closely attached to the upper margin of the sternum. It is in relation, in front, Avith the integu- ment; behind, Avith the Sterno-thyroid muscles. The Costo-clavicular Ligament (rhomboid) is a short, flat, and strong band of ligamentous fibres of a rhomboid form, attached, below, to the upper and inner part of the cartilage of the first rib; and, ascending obliquely backAvards and out- wards, to be attached, above, to the rhomboid depression on the under surface of the inner extremity of the clavicle. It is in relation, in front, with the tendon of origin of the Subclavius ; behind, with the subclavian vein. The Interarticular Fibro-cartilage is a flat and nearly circular disc, inter- posed betAveen the articulating surfaces of the sternum and clavicle. It is attached above, to the upper and posterior border of the clavicle; below, to the cartilage of 158 ARTICULATIONS. the first rib, at its junction Avith the sternum; and by its circumference to the anterior and posterior sterno-clavicular ligaments. It is thicker at the circum- ference, especially its upper and back part, than at its centre, or below. It divides the joint into twTo caAlties, each of Avhich is furnished Avith a separate synovial membrane ; Avhen the fibro-cartilage is perforated, Avhich not unfrequently occurs, the synovial membranes communicate. Of the two Synovial Membranes found in this articulation, one is reflected over the sternal end of the clavicle, the adjacent surface of the fibro-cartilage, and cartilage of the first rib ; the other is placed between the articular surface of the sternum and adjacent surface of the fibro-cartilage; the latter is the more loose of the tAvo. They seldom contain much synovia. Actions. This articulation is the centre of the movements of the shoulder, and admits of motion in nearly every direction—upwards, doAvnwards, backwards, forwards, as well as circumduction ; the sternal end of the clavicle and the inter- articular cartilage gliding on the articular surface of the sternum. 2. Scapuloclavicular Articulation. The Scapulo-clavicular is an arthrodial joint, formed between the outer extre- mity of the clavicle, and the upper edge of the acromion process of the scapula. Its ligaments are the Superior Acromio-clavicular. Inferior Acromio-clavicular. ( Trapezoid Coraco-clavicular < and ( Conoid. Interarticular Fibro-cartilage. Tavo Synovial Membranes. The Superior Acromio-clavicular Ligament is a broad band of fibres, of a quadrilateral form, Avhich covers the superior part of the articulation, extending betAveen the upper part of the outer end of the clavicle, and the superior part of the acromion. It is composed of parallel fibres, Avhich interlace, above, with the aponeurosis of the Trapezius and Deltoid muscles ; beloAV, it is in contact with the interarticular fibro-cartilage and synovial membranes. The Inferior Acromio-clavicular Ligament, somewhat thinner than the pre- ceding, covers the inferior part of the articulation, and is attached to the adjoining surfaces of the tAvo bones. It is in relation, above, Avith the interarticular fibro- cartilage (Avhen it exists) and the synovial membranes; beloAv, Avith the tendon of the Supraspinatus. These tAvo ligaments are continuous Avith each other in front and behind, and form a complete capsule around the joint. The Coraco-clavicular Ligament serves to connect the clavicle with the coracoid process of the scapula. It consists of tAvo distinct fasciculi, which have received separate names. The Trapezoid Ligament, the anterior and external fasciculus, is a broad, thin, quadrilateral-shaped band of fibres, placed obliquely betAveen the acromion process and the clavicle. It is attached, below, to a rough line at the inner and back part of the upper surface of the coracoid process; above, to the oblique line on the under surface of the clavicle. Its anterior border is free; its posterior is joined with the conoid ligament, forming by their junction a projecting angle. The Conoid Ligament, the posterior and internal fasciculus, is a dense band of fibres, conical in form, the base being turned upAvards, the summit dowmvards. It is attached by its apex to a rough depression at the anterior and inner side of the base of the coracoid process, internal to the preceding ; above, by its expanded base, to the rough tubercle on the under surface of the clavicle. These ligaments are in relation, in front, Avith the Subclavius; behind, Avith the Trapezius: they serve to limit rotation of the scapula forwards and backwards. PROPER LIGAMENTS OF SCAPULA. 159 The Interarticular Fibro-cartilage is most frequently absent in this articula- tion. When it exists, it generally only partially separates the articular surfaces, and occupies the upper part of the articulation. More rarely, it completely sepa- rates this joint into tAvo cavities. Fig. 114.—The Left Shoulder Joint, Scapula-clavicular Articulations, and Proper Ligaments of the Scapula. ' There are tivo Synovial Jfcmbranes Avhere a complete interarticular cartilage exists; more frequently there is only one synovial membrane. Actions. The movements of this articulation are of two kinds. 1. A gliding motion of the articular end of the clavicle on the acromion. 2. Rotation of the scapula forAvards and backAvards upon the clavicle, the extent of this rotation being limited by the tAvo portions of the coraco-clavicular ligament. 3. Proper Ligaments of the Scapula. The proper ligaments of the scapula are Coraco-acromial. Transverse (Coracoid). The Coraco-acromial Ligament is a broad, thin, and flat band, of a triangular shape, extended transversely across the upper part of the shoulder joint, between the coracoid process and the acromion. It is attached by its apex to the summit of the acromion, just in front of the articular surface for the clavicle, and by its broad base to the whole length of the outer border of the coracoid process. Its posterior fibres are directed obliquely backAvards and outAvards, its anterior fibres transversely. This ligament completes the vault formed by the acromion and cora- coid processes for the protection of the head of the humerus. It is in relation, above, with the clavicle and under surface of the deltoid ; below, Avith the tendon of 160 ARTICULATIONS. the Supraspinatus muscle, a bursa being interposed. Its anterior border is con- tinuous with a dense cellular laminse that passes beneath the deltoid upon the tendons of the Supraspinal and Infraspinati muscles. The Transverse or Coracoid Ligament is a thin and flat fasciculus, narrower at the middle than at the extremities, attached by one end to the base of the cora- coid process, and by the other, to the inner extremity of the scapular notch, which it converts into a foramen. The suprascapular nerve passes through this foramen, its accompanying vessels above it. 4. Shoulder Joint. The Shoulder is an enarthrodial or ball and socket joint. The bones en- tering into its formation are the large globular head of the humerus, which is received into the shallow glenoid cavity of the scapula, an arrangement which permits of very considerable movement, whilst the joint itself is protected against displacement by the strong ligaments and tendons which surround it, and above by an arched vault, formed by the under surface of the coracoid and acromion pro- cesses, and the coraco-acromial ligament. The two articular surfaces are covered by a layer of cartilage, which on the head of the humerus is thicker at the centre than at the circumference, the reverse being observed in the glenoid cavity. Its ligaments are the Capsular. Glenoid. Coraco-humeral. Synovial Membrane. The Capsular Ligament completely encircles this articulation; being attached, above, to the circumference of the glenoid cavity beyond the glenoid ligament; below, to the margin of the neck of the humerus, approaching nearer to the articular carti- lage above, than in the rest of its extent. It is thicker above than below, remark- ably loose and lax, and much larger and longer than is necessary to keep the bones in contact, allowing them to be separated from each other more than an inch, an evident provision for that extreme freedom of movement which is peculiar to this articulation. Its external surface is strengthened above by the Supraspi- natus; above and internally, by the coraco-humeral ligament; below, where it is thin and weak, the long tendon of the Triceps is separated from it by a little loose areolar tissue; externally, the tendons of the Infraspinatus and Teres minor are firmly attached to it; and internally, the tendon of the Subscapularis. The cap- sular ligament usually presents three openings: one at its inner side, partially filled up by the tendon of the Subscapularis; it establishes a communication between the synovial membrane of the joint, and a bursa beneath the tendon of that muscle; a second, not constant, at its external part, where a communication exists between the joint and a bursal sac belonging to the Infraspinatus muscle. The third is seen in the loAver border of the ligament, between the tAvo tuberosities, for the passage of the tendon of the Biceps muscle. The Coraco-humeral or Accessory Ligament, is a broad band which strengthens the upper and inner part of the capsular ligament. It arises from the outer border of the coracoid process, and descends obliquely downwards and outwards to the anterior part of the great tuberosity of the humerus, being blended with the tendon of the Supraspinatus muscle. This ligament is intimately united to the capsular in the greater part of its extent. The Glenoid Ligament is a fibro-cartilaginous band attached around the margin of the glenoid cavity. It is triangular on section, the thickest portion being fixed to the circumference of the cavity, the free edge being thin and sharp. It appears to be mainly formed of the fibres of the long tendon of the Biceps muscle, bifur- cating at the upper part of the glenoid cavity into tAvo fasciculi, which encircle its margin and unite at its lower part. This ligament deepens the cavity for articu- lation, and protects the edges of the bone. It is lined by the synovial membrane. The Synovial Membrane lines the glenoid cavity and the fibro-cartilaginous rim ELBOW JOINT. 161 115.—Left Elbow Joint, showing and Internal Ligaments. Anterior surrounding it; it is then reflected over the internal surface of the capsular liga- ment, lines the loAver part and sides of the neck of the humerus, and is con- tinued over the cartilage covering the head of this bone. The long tendon of the Hiccps muscle which passes through the joint, is inclosed in a tubular sheath of synovial membrane, which is reflected upon it at the point where it perforates the capsule, and is continued around it as far as the summit of the glenoid cavity where it is continuous with that portion of the membrane which covers its surface! The tendon of the Biceps is thus enabled to traverse the articulation, but is not contained in the interior of the synovial cavity. The synovial membrane commu- nicates with a large bursal sac beneath the tendon of the Subscapularis, by an opening at the inner side of the capsular ligament; it also occasionally communi- cates with another bursal sac, beneath the tendon of the Infraspinatus, through an orifice at its upper part. A third bursal sac, Avhich does not communicate with the joint, is placed between the under surface of the deltoid and the outer surface of the capsule. The Muscles in relation with this joint'are, above, the Supraspinatus; beloAV, the long tendon of the Triceps; internally, the Subscapularis; externally, the Infraspinatus and Teres minor; Avithin, the long tendon of the Biceps. ' The Deltoid is placed most externally, and covers the articulation on its outer side and in front and behind. The Arteries supplying this joint are articular branches of the anterior and posterior circumflex, and suprascapular. The Nerves are derived from the cir- Fij cumflex and suprascapular. Actions. The shoulder joint is capable of movement in almost any direction, for- wards, backAvards, abduction, adduction, circumduction, and rotation. 5. Elboav Joint. The Elbow is a ginglymoid or hinge joint. The bones entering into its forma- tion are the trochlear surface of the humerus, Avhich is receiATed in the greater sigmoid cavity of the ulna, and admits of the movements peculiar to this joint, those of flexion and extension, Avhilst the cup-shaped depression of the head of the radius articulates with the radial tubero- sity of the humerus, its circumference with the lesser sigmoid cavity of the ulna, al- lowing of the movement of rotation of the radius on the ulna, the chief action of the superior radio-ulnar articulation. These various articular surfaces are covered with a thin layer of cartilage, and connected together by the folloAving ligaments:— Anterior Ligament. Posterior Ligament. Internal Lateral. External Lateral. Synovial Membrane. The Anterior Ligament (Fig. 115) is a broad and thin membranous layer, which covers the anterior surface of the joint. It is attached to the humerus immediately 13 162 ARTICULATIONS. Fig. 116.—Left Elbow Joint, showing Pos- terior and External Ligaments. above the coronoid fossa; below, to the anterior surface of the coronoid process of the ulna and orbicular ligament, being continuous on each side Avith the lateral ligaments. Its superficial or oblique fibres pass from the internal tuberosity of the humerus outAvards to the orbicular ligament. The middle fibres, vertical in direction, pass from the upper part of the coronoid depression, and become blended with the preceding. A third, or transverse set, intersect these at right angles. This ligament is in relation, in front, Avith the Brachialis anticus; behind, with the synovial membrane. The Posterior Ligament is a thin and loose membranous fold, attached, above, to the loAver end of the humerus, immediately above the olecranon depression; beloAV, to the margin of the olecranon. The superficial or transverse fibres pass betAveen the adjacent margins of the olecranon fossa. The deeper portion consists of vertical fibres, which pass from the upper part of the olecranon fossa to the margin of the olecranon. This ligament is in relation, behind, Avith the tendon of the Triceps and Anconeus; in front, with the synovial membrane. The Internal Lateral Ligament is a thick, triangular band of ligamentous fibres, consisting of two distinct portions, an anterior and posterior. The ante- rior portion, directed obliquely forAvards, is attached, above, by its apex, to the front part of the internal condyle of the humerus; and, below, by its broad base to the inner margin of the coronoid process. The posterior portion, also of triangular form, is attached, above, by its apex, to the loAver and back part of the internal condyle ; below, to the inner margin of the olecranon. This ligament is in relation, internally, with the Triceps and Flexor carpi ulnaris muscles and the ulnar nerve. The External Lateral Ligament (Fig. 116) is a short and narrow fibrous fasci- culus, less distinct than the internal, attached, above, to the external condyle of the hume- rus; beloAv, to the orbicular ligament, some of its most posterior fibres passing over that ligament to be inserted into the outer margin of the greater sigmoid cavity. This ligament is intimately blended Avith the tendon of origin of the Supinator brevis muscle. The Synovied Membrane is very extensive, It covers the articular surface of the humerus, and lines the coronoid and olecranon depres- sions on that bone; from these points, it is re- flected over the anterior, posterior, and lateral ligaments; lines the greater sigmoid cavity, the concave depression on the head of the radius; and forms a pouch betAveen the lesser sigmoid cavity, the internal surface of the annular liga- ment, and the circumference of the radius. The Muscles in relation with this joint are, in front, the Brachialis anticus; behind, the Triceps and Anconeus; externally, the Supina- tor brevis, and the common tendon of origin of the Extensor muscles; internally, the common tendon of origin of the Flexor muscles, the Flexor carpi ulnaris, and ulnar nerve. The Arteries supplying this joint are derived from the communicating branches between the superior profunda, inferior profunda, and ana- stomotic branches of the Brachial, with the anterior, posterior, and interosseous recurrent branches of the Ulnar,and the recurrent branch of the Radial. These vessels form a complete chain of inosculation around this joint. RADIO-ULNAR. 163 The Nerves are derived from the ulnar, as it passes between the internal condyle and the olecranon. Actions. The elbow is one of the most perfect hinge-joints in the body ; its movements are consequently limited to flexion and extension, the exact apposition of the articular surfaces preventing the least lateral motion. The movement of flexion is limited by the coronoid process, and that of extension by the olecranon process. 6. Radio-ulnar Articulations. The articulation of the radius Avith the ulna is effected by ligaments, which connect together both extremities as well as the centre of these bones. They may, consequently, be subdivided into three sets : 1, the superior radio-ulnar; 2, the middle radio-ulnar; and 3, the inferior radio-ulnar articulations. (1.) Superior'Radio-ulnar Articulation. This articulation is a lateral ginglymoid joint. The bones entering into its formation are the inner side of the circumference of the head of the radius, which is received into the lesser sigmoid cavity of the ulna. These surfaces are covered with cartilage, and invested with a duplicature of synovial membrane, continuous with that which lines the elbow joint. Its only ligament is The Annular or Orbicular. The Orbicular Ligament (Fig. 116) is a strong flat band of ligamentous fibres, which surrounds the head of the radius, and retains it in firm connection Avith the lesser sigmoid cavity of the ulna. It forms about three-fourths of a fibrous ring, attached by each end to the extremities of this cavity, and is broader at the upper part of its circumference than below, which senses to hold the head of the radius more securely in its position. Its outer surface is strengthened by the external lateral ligament and affords partial origin to the Supinator brevis muscle. Its internal turf ace is smooth, and lined by the synovial membrane of the elbow joint. Actions. ^ The movement which takes place in this articulation is limited to rota- tion of the inner part of the head of the radius Avithin the orbicular ligament, and upon the lesser sigmoid cavity of the ulna ; rotation forAvards being called prona- tion; rotation backAvards, supination. (2.) Middle Radio-ulnar Articulation. The interval between the radius and ulna in the middle of the forearm is occu- pied by two ligaments. Oblique. Interosseous. The Oblique or Round Ligament (Fig. 115) is a small round fibrous cord, which extends obliquely dowmvards and outAvards, from the tubercle of the ulna at the base of the coronoid process, to the radius a little below the bicipital tuberosity. Its fibres run in the opposite direction to those of the interosseous ligament; and it appears to be placed as a substitute for it in the upper part of the interosseous interval. The Interosseous Ligament is a broad and thin plane of aponeurotic fibres, de- scending obliquely doAvnwards and inwards, from the interosseous ridge on the radius to that on the ulna. It is deficient above, commencing about an inch be- neath the tubercle of the radius; broader in the middle than at either extremity; and presents an oval aperture just above its lower margin for the passage of the anterior interosseous vessels to the back of the forearm. This ligament serves to connect the bones, and to increase the extent of surface for the attachment of the deep muscles. Between its upper border and the oblique ligament an interval exists, through which the posterior interosseous vessels pass. Two or three fibrous bands are occasionally found on the posterior surface of this membrane, which 164 ARTICULATIONS. descend obliquely from the ulna towards the radius, and Avhich have consequently a direction contrary to that of the other fibres. It is in relation, in front, by its upper three-fourths (radial margin) with the Flexor longus pollicis (ulnar margin), with the Flexor profundus digitorum (lying upon the interval betAveen which are the anterior interosseous vessels and nerve), by its lower fourth Avith the Pronator quadratus; behind, with the Supinator brevis, Extensor osste metacarpi pollicis, Extensor primi internodii pollicis, Extensor secundi internodii pollicis, Extensor indicis ; and, near the wrist, with the anterior interosseous artery and posterior interosseous nerve. (3.) Inferior Radio-ulnar Articulation. This is a lateral ginglymoid joint, formed by the head of the ulna being received into the sigmoid cavity at the inner side of the loAver end of the radius. The articular surfaces are invested by a thin layer of cartilage, and connected together by the following ligaments. Anterior Radio-ulnar. Posterior Radio-ulnar. Triangular Interarticular Fibro-cartilage. Synovial Membrane. The Anterior Radio-ulnar Ligament (Fig. 117) is a narrow band of fibres, ex- tending from the anterior margin of the sigmoid cavity of the radius to the ante- rior surface of the head of the ulna. The Posterior Radio-ulnar Ligament (Fig. 118) extends between the same points on the posterior surface of the articulation. The Interarticular Fibro-cartilage (Fig. 119) is a thick fibro-cartilaginous lamella, of a triangular form, placed transversely, completing the wrist joint, and binding the loAver ends of the radius and ulna firmly together. Its circumference is more dense than its centre, which is thin and occasionally perforated ; and it is thinner and broader externally than internally. It is attached by its apex to a depres- sion which separates the styloid process of the ulna from the head of that bone; by its base, Avhich is thin, to the prominent edge of the radius, which sepa- rates the sigmoid cavity from the carpal articulating surface, and by its anterior and posterior margins to the ligaments of the radio-carpal articulation. Its upper surface, smooth and concave, is contiguous Avith the head of the ulna; its under surface, also concave and smooth, Avith the cuneiform bone. Both surfaces are lined by a synovial membrane : the superior surface, by one peculiar to the radio-ulnar articulation; the inferior surface, by the synovial membrane of the Avrist. The Synovial Membrane of this articulation has been called, from its extreme looseness, the membrana sacciformis; it covers the articular surface of the head of the ulna, and where reflected from this bone on to the radius, forms a very loose cul-de-sac; from the radius it is continued over the upper surface of the fibro- cartilage. The quantity of synovia Avhich it contains is usually considerable. When the fibro-cartilage is perforated, this synovial membrane is continuous with that Avhich lines the Avrist joint. _ . Actions. The movement Avhich occurs in the inferior radio-ulnar articulation is just the inverse of that which takes place betAveen the tAvo bones above ; it is limited to rotation of the radius around the head of the ulna ; rotation fonvards being termed pronation, rotation backwards supination. In pronation, the sigmoid cavity glides fonvard on the articular edge of the ulna ; in supination, it rolls in the op- posite direction, the extent of these movements being limited by the anterior and posterior ligaments. 7. "Wrist Joint. The Wrist presents most of the characters of an enarthrodial joint. The parts entering into its formation are the loAver end of the radius, and under surface WRIST JOINT. 165 of the triangular interarticular fibro-cartilage, above; and the scaphoid, semilunar, and cuneiform bones beloAV. The articular surfaces of the r.ulius and interarticular Fig. 117.—Ligaments of Wrist and Hand. Anterior View. INFERIOR RADIO-ULNAR ARTIC" WRIST-JOINT CARPAL ARTIC?? CARPO-METACARPAL ARTIC ?1 fibro-cartilage form a transversely elliptical concave surface. The radius is sub- divided into tAvo parts by a line extending from bofore backAvards ; and these, together with the interarticular cartilage, form three facets, one for each carpal Fig. 118.—Ligaments of Wrist and Hand. Posterior View. Inferior Jiadio -ulnar Ar Wrist-Join Carpal Art Cn rr> o-Mietacarpn I ArticV? bone. The three carpal bones are connected together, and form a rounded convex surface, which is received into the cavity above mentioned. All the bony surfaces 166 ARTICULATIONS. of this articulation are covered Avith cartilage, and connected together by the following ligaments. External Lateral. Anterior. Internal Lateral. Posterior. Synovial Membrane. The External Lateral Ligament extends from the summit of the styloid pro- cess of the radius to the outer side of the scaphoid, some of its fibres being prolonged to the trapezium and annular ligament. The Interned Lettered Ligament is a rounded cord, attached, above, to the ex- tremity of the styloid process of the ulna; below, it divides into two fasciculi, which are attached, one to the inner side of the cuneiform bone, the other to the pisiform bone and annular ligament. The Anterior Ligament is a broad membranous band, consisting of three fasci- culi, attached, above, to the anterior margin of the lower end of the radius, its styloid process, and the ulna; its fibres pass doAvnwards and inwards, to be inserted into the anterior surface of the scaphoid, semilunar, and cuneiform bones. This ligament is perforated by numerous apertures for the passage of vessels, and is in relation, in front, with the tendons of the Flexor profundus digitorum and Flexor longus pollicis; behind, with the synoAnal membrane of the wrist joint. The Posterior Ligament, less thick and strong than the anterior, is attached, above, to the posterior border of the loAver end of the radius : its fibres descend obliquely dowmvards and inwards to be attached to the posterior surface of the scaphoid, semilunar, and cuneiform bones, its fibres being continuous Avith those of the dorsal carpal ligaments. This ligament is in relation, behind, Avith the extensor tendons of the fingers; in front, Avith the synovial membrane of the wrist. The Synovial Membrane lines the loAver end of the radius and under surface of the triangular interarticular fibro-cartilage above ; and being reflected on the inner surface of the ligaments above-mentioned, covers the convex surface of the scaphoid, semilunar, and cuneiform bones below. Relations. The wrist joint is covered in front by the flexor, and behind by the extensor tendons ; it is also in relation Avith the radial and ulnar arteries. The Arteries supplying this joint are the anterior and posterior carpal branches of the Radial and Ulnar, the anterior and posterior interosseous, and some ascending branches from the deep palmar arch. The Nerves are derived from the posterior interosseous. Actions. The movements permitted in this joint are flexion, extension, abduc- tion, adduction, and circumduction. It is totally incapable of rotation, one of the characteristic movements in true enarthrodial joints. 8. Articulations of the Carpus. These articulations may be subdivided into three sets. 1. The articulation of the first toav of carpal bones. 2. The articulation of the second toav of carpal bones. 3. The articulation of the two rows Avith each other. (1.) Articulation of the First Roav of Carpal Bones. These are arthrodial joints. The articular surfaces are covered Avith cartilage, and connected together by the following ligaments. Two Dorsal. Two Palmar. Two Interosseous. The Dorsal Ligaments, tAvo in number, are placed transversely behind the hones of the first row; they connect the scaphoid and semilunar, and the semilunar and cuneiform. The Palmar Ligaments, also tAvo in number, connect the scaphoid and semi- OF THE CARPUS. 167 lunar, and the semilunar and cuneiform bones; they are less strong than the dorsal, and placed very deep under the anterior ligament of the Avrist. The Interosseous Ligaments (Fig. 118) are tAvo narroAv bundles of dense fibrous tissue, connecting the semilunar bone, on one side with the scaphoid, on the other with the cuneiform bone. They close the upper part of the interspaces between the scaphoid, semilunar, and cuneiform bones, their upper surfaces being smooth, and lined by the synovial membrane of the wrist joint. The articulation of the pisiform with the cuneiform, is provided with a separate synovial membrane, protected by a thin capsular ligament. There are also two strong fibrous fasciculi, which connect this bone to the unciform, and base of the fifth metacarpal bone. (2.) Articulation of the Second Roav of Carpal Bones. These are also arthrodial joints, the articular surfaces being covered Avith carti- lage, and connected by the following ligaments. Three Dorsal. Three Palmar. Tavo Interosseous. The three Dorsal Ligaments extend transversely from one bone to another on the dorsal surface, connecting the trapezium Avith the trapezoid, the trapezoid with the os magnum, and the os magnum Avith the unciform. The three Palmar Ligaments have a similar arrangement on the palmar surface. The two Interosseous Ligaments, much thicker than those of the first row, are placed one on each side of the os magnum, connecting it Avith the trapezoid exter- nally, and the unciform internally. The former is less distinct than the latter. (3.) Articulation of the Tavo Roavs of Carpal Bones avith each other. The articulation between the two rows of the carpus consists of an enarthrodial joint in the middle, formed by the reception of the os magnum into a cavity formed by the scaphoid and semilunar bones, and of an arthrodial joint on each side, the outer one formed by the articulation of the scaphoid Avith the trapezium and trapezoid, the internal one by the articulation of the cuneiform and unciform. The articular surfaces are covered by a thin layer of cartilage, and connected by the folloAving ligaments :— Anterior or Palmar. External Lateral. Posterior or Dorsal. Internal Lateral. Synovial Membranes. The Anterior or Palmar Ligaments consist of short fibres, which pass obliquely between the bones of the first and second row on the palmar surface. The Posterior or Dorsal Ligaments have a similar arrangement on the dorsal surface of the carpus. The Lateral Ligaments are \rery short; they are placed, one on the radial, the other on the ulnar side of the carpus; the former, the stronger and more distinct, connecting the scaphoid' and trapezium bones, the latter, the cuneiform and unci- form : they are continuous Avith the lateral ligaments of the Avrist joint. There are two Synovial Membranes found in the articulation of the carpal bones Avith each other. The first of these, the more extensive, lines the under surface of the scaphoid, semilunar, and cuneiform bones, sending upwards two prolongations between their contiguous surfaces; it is then reflected over the bones of the second row, and sends down three prolongations between them, Avhich line their contiguous surfaces, and invest the carpal extremities of the four outer metacarpal bones. The second is the synovial membrane betAveen the pisiform and cuneiform bones. Actions. The partial movement which takes place betAveen the bones of each 1'oav is very considerable; the movement betAveen the two rowTs is more marked, but limited chiefly to flexion and extension. 168 ARTICULATIONS. 0. Carpo-metacarpal Articulations. Articulation of the First Metacarpal Bone avith the Trapezium. This is an enarthrodial joint. Its ligaments are a capsular and synovial mem- brane. The capsular ligament is a thick but loose capsule, Avhich passes from the circumference of the upper extremity of the metacarpal bone, to the romdi edge bounding the articular surface of the trapezium ; it is thickest externally and behind, and lined by a separate synovial membrane. Articulation of the Four inner Metacarpal Bones with the Carpus. The joints formed betAveen the carpus and four inner metacarpal bones, are con- nected together by dorsal, palmar, and interosseous ligaments. The Dorsal Ligaments, the strongest and most distinct, connect the carpal and metacarpal bones on their dorsal surface. The second metacarpal bone receives tAvo fasciculi, one from the trapezium, the other from the trapezoid; the third me- tacarpal receives one from the os magnum ; the fourth tAvo, one from the os mag- num, and one from the unciform; the fifth receives a single fasciculus from the unciform bone. The Palmar Ligaments have a someAvhat similar arrangement on the palmar surface, Avith the exception of the third metacarpal, Avhich has three ligaments an external one from the trapezium, situated above the sheath of the tendon of the Flexor carpi radialis ; a middle one, from the os magnum ; and an internal one, from the unciform. The Interosseous Ligaments consist of short thick fibres, which are limited to one part of the carpo-metacarpal articulation ; they connect the inferior angles of the os magnum and unciform Avith the adjacent surfaces of the third and fourth metacarpal bones. The Synovial Membrane is a continuation of that betAveen the two rows of carpal bones. Occasionally, the unciform has a separate synovia] membrane, lining it and the fourth and fifth metacarpal bones. The Synovial membranes of the wrist (Fig. 119) are thus seen to be five in Fi- ll 9-—Vertical Section through the Articulations at the Wrist, showing the five Synovial Membranes. CARPO-METACARPAL AND METACARPOPHALANGEAL. 169 number. The first, the membrana sacciformis, lining the loAver end of the ulna the sigmoid cavity of the radius, and upper surface of the triangular interarticular fibro-cartilage. The second lines the loAver end of the radius and interarticular fibro-cartilage aboA^e, and the scaphoid, semilunar, and cuneiform bones beloAv. The third, the most extensive, covers the contiguous surfaces of the tAvo rows of carpal bones, and passing betAveen the bones of the second range, lines the carpal extre- mities of the four inner metacarpal bones. The fourth lines the adjacent sur- faces of the trapezium and metacarpal bone of the thumb. And the fifth, the adjacent surfaces of the cuneiform and pisiform bones. Actions. The movement permitted in the carpo-metacarpal articulations is limited to a slight gliding of the articular surfaces upon each other, the extent of Avhich varies in. the different joints. Thus the articulation of the metacarpal bone of the thumb with the trapezium is most movable, then the fifth metacarpal, and then the fourth. The second and third are almost immovable. In the articulation of the metacarpal bone of the thumb Avith the trapezium, the movements permitted are flexion, extension, adduction, abduction, and circumduction. Articulation of the Metacarpal Bones avith each other. The carpal extremities of the metacarpal bones of the fingers articulate with one another at each side by small surfaces covered with cartilage, and connected together by dorsal, palmar, and interosseous ligaments. The Dorsal or Palmar Ligaments pass transversely from one bone to another on the dorsal and palmar surfaces ; the Interosseous Ligaments passing betAveen their contiguous surfaces, just beneath their lateral articular facets. The Synovial Membrane lining the lateral facets is a reflection of that between the two rows of carpal bones. The digital extremities of the metacarpal bones of the fingers are connected together by the transverse ligament, a narroAv fibrous band, passing transversely across their under surfaces, and blended Avith the ligaments of the metacarpo-pha- langeal articulations. Its anterior surface presents four grooves for the passage of the flexor tendons, and its sides are continuous Avith their sheaths. Its poste- rior surface blends' Avith the ligaments of the metacarpophalangeal articulation. 10. Metacarpophalangeal Articulations (Fig. 120). These articulations are of the ginglymoid kind, formed by the reception of each of the rounded heads of the metacarpal bones of the four fingers, into a superficial cavity in the extremity of the first phalanges. They are connected by the fol- lowing ligaments: Anterior. Two Lateral. Synovial Membrane. The Anterior Ligaments are very thick and dense, they are placed on the palmar surface of the joint in the interval betAveen the lateral ligaments, to Avhich they are connected; they are loosely united to the metacarpal bone, but very firmly to the base of the first phalanges. Their palmar surface is intimately united to the transverse ligament, each ligament forming with it a groove for the passage of the flexor tendons, the sheath surrounding Avhich is connected to it at each side. By their internal surface they form part of the articular surface for the head of the metacarpal bone, and are lined by a synovial membrane. The Latered Ligaments are thick and strong rounded cords, placed one on each side of the joint, attached by one extremity to the sides of the head of the meta- carpal bones, and by the other, to the contiguous extremity of the phalanges. The Posterior Ligament is supplied by the extensor tendon of the fingers placed over the back of each joint. Actions. The movements Avhich occur in these joints are flexion, extension, adduction, abduction, and circumduction: the lateral movements are very limited. 170 ARTICULATIONS. »§,' Meteiearpo -f'liuletng^d Artie'.' 11. Articulations of the Phalanges. These are ginglymoid joints, connected by the folloAving ligaments:— Fig. 120.—Articulations of the Phalanges. ' Iavo Lateral. $? Synovial Membrane. The arrangement of these liga- ments is similar to those in the preceding articulations ; the ex- tensor tendon supplies the place of a posterior ligament. Actions. The only movements permitted in the phalangeal joints are flexion and extension; these movements are more extensive between the first and second pha- langes than between the second and third. The movement of flex- ion is very extensive, but exten- sion is limited by the anterior and lateral ligaments. ARTICULATIONS OF THE LOWER EXTREMITY. The articulations of the lower extremity comprise the following groups. 1. The hip joint. 2. The knee joint. 3. The articulations between the tibia and fibula. 4. The ankle joint. 5. The arti- culations of the tarsus. 6. The tarso-metatarsal articulations. 7. The metatarso-phalangeal arti- culations. 8. The articulation of the phalanges. 1. Hip Joint (Fig. 121). This articulation is an enar- throdial, or ball and socket joint, formed by the reception of the globular head of the femur into the cup-shaped cavity of the acetabulum. These two articulating surfaces are covered Avith cartilage, that on the head of the femur being thicker at the centre than at the circumference, and covering the entire surface with the exception of a depression just beloAv its centre for the ligamentum teres; that covering the acetabulum is much thinner at the centre than at the circumference, and is deficient in the situation of the circular depression at the bottom of this cavity. The ligaments of this joint are the Capsular. Cotyloid. Ilio-femoral. Transverse. Teres. Synovial Membrane. The Capsular Ligament is a strong, dense, ligamentous capsule, embracing the margin of the acetabulum above, and surrounding the neck of the femur below. Its upper circumference is attached to the acetabulum two or three lines external to the cotyloid ligament; but opposite the notch Avhere the margin of this cavity is deficient, it is connected with the transverse ligament, and by a feAV fibres to the edge of the obturator foramen. Its loiver circumference surrounds the neck of PJiaTnngral Artie .*"*' HIP JOINT. 171 the femur, being attached, in front, to the spiral or anterior intertrochanteric line; above, to the base of the neck ; behind, to the middle of the neck of the bone, about three-quarters of an inch from the posterior intertrochanteric line. It is Fig. 121.—Left Hip Joint laid open. much thicker at the upper and anterior part of the joint, where the greatest amount of resistance is required, than beloAV, where it is thin, loose, and longer than in any other situation. Its external surface is rough, covered by numerous muscles, and separated in front from the Psoas and Iliacus by a synovial bursa, which not unfrequently communicates by a circular aperture with the cavity of the joint. It differs from the capsular ligament of the shoulder, in being much less loose and lax, and in not being perforated for the passage of a tendon. The Ilio-femoral Ligament (Fig. 110) is an accessory band of fibres, extending obliquely across the front of the joint: it is intimately connected Avith the capsular ligament, and serves to strengthen it in this situation. It is attached above to the anterior inferior spine of the ilium ; below, to the anterior intertrochanteric line. The Ligamentum Teres is a flat, triangular band of fibres, implanted by its apex into the depression just below the middle of the head of the femur, and by its broad base, Avhich consists of two bundles of fibres, into the margins of the notch at the bottom of the acetabulum, becoming blended with the transverse ligament. It is formed of a bundle of fibres, the thickness and strength of Avhich is very variable, surrounded by a tubular sheath of synovial membrane. Sometimes the synovial fold only exists, or the ligament may be altogether absent. The Cotyloid Ligament is a fibro-cartilaginous rim, attached to the margin of the acetabulum, the cavity of Avhich it deepens ; at the same time it protects the edges of the bone, and fills up the inequalities on its surface. It is prismoid in form, its base being attached to the margin of the acetabulum, its opposite edge being free and sharp; Avhilst its tAvo surfaces are invested by synovial membrane, the external 172 ARTICULATIONS. one being in contact with the capsular ligament; the internal being inclined inwards so as to narroAv the acetabulum, and embrace the cartilaginous surface of the head of the femur. It is much thicker above and behind than beloAV and in front, and consists of close, compact fibres, which arise from different points of the circum- ference of the acetabulum, and interlace with each other at very acute angles. The Transverse Ligament is a strong, flattened band of fibres, Avliich crosses the notch at the loAver part of the acetabulum, and converts it into a foramen. It is continuous at each side with the cotyloid ligament, and consists of fibres which arise from each side of the notch, and pass across each other. An interval is left beneath this ligament for the passage of nutrient vessels to the joint. The Synovial Membrane is very extensive. It invests the cartilaginous surface of the head of the femur, and all that portion of the neck Avhich is contained within the joint; from this point it is reflected on the internal surface of the capsular ligament, covers both surfaces of the cotyloid ligament, and lines the cavity of the acetabulum, covers the mass of fat contained in the fossa at the bottom of this cavity, and is prolonged in the form of a tubular sheath around the ligamentum teres on to the head of the femur. The Muscles in relation Avith this joint are, in front, the Psoas and Iliacus, sepa- rated from the capsular ligament by a synovial bursa ; above, the short head of the Rectus and Glutasus minimus, the latter being closely adherent to it; internally, the Obturator externus and Pectineus; behind, the Pyriformis, Gemellus superior, Obturator internus, Gemellus inferior, Obturator externus, and Quadratus femoris. The Arteries supplying it are derived from the obturator, sciatic, internal cir- cumflex, and gluteal. The nerves are articular branches from the sacral plexus, great sciatic, obturator, and accessory obturator nerves. Actions. The movements of Fig. 122.—Right Knee Joint. Anterior View. the hip, like all enarthodial joints, are very extensive; they are flexion, extension, adduction, abduction, circumduction, and rotation. 2. The Knee Joint. The knee is a ginglymoid, or hinge joint; the bones entering into its formation are the con- dyles of the femur above, the head of the tibia below, and the patella in front. The articular surfaces are covered with car- tilage, lined by synovial mem- brane, and connected together by ligaments, some of which are placed on the exterior of the joint, whilst others occupy its interior. External Ligaments. Anterior, or Ligamentum Pa- tellae. Posterior, or Ligamentum Posti- cum Winslowii. Internal Lateral. Two External Lateral. Capsular. KNEE JOINT. 173 Internal Ligaments. Anterior, or External Crucial. Posterior, or Internal Crucial. Synovial Membrane Tavo Semilunar Fibro-cartilages. Transverse. Coronary. f Ligamentum mucosum. \ Ligamenta alaria. %- The Anterior Ligament, or Ligamentum Patella? (Fig. 122), is that portion of the common tendon of the extensor muscles of the thigh which is continued from the patella to the tubercle of the tibia, supplying the place of an anterior ligament. It is a strong, flat, ligamentous band, attached, above, to the apex of the patella and the rough depression on its posterior surface; below, to the lower part of the tuberosity of the tibia; its superficial fibres being continuous across the front of the patella Avith those of the tendon of the Rectus femoris. Tavo synovial bursae are connected Avith this ligament and the patella; one is interposed betAveen the patella and the skin covering its anterior surface; the other, of small size, betAveen the ligamentum patellae and the upper part of the tuberosity of the tibia. The posterior surface of this ligament is separated above from the knee joint by a large mass of adipose tissue; its lateral margins are continuous "with the aponeu- roses derived from the Vasti muscles. The Posterior Ligament, Li- Fig 123.—Right Knee Joint. Posterior View. gamentum Posticum Winslowii (Fig. 123), is a broad, flat, fibrous band, which covers over the whole of the back part of the joint. It consists of tAvo lateral portions, formed chiefly of ver- tical fibres, Avhich arise above from the condyles of the femur, and connected beloAv Avith the back part of the head of the tibia, being closely united with the tendons of the Gastrocnemii, Plantaris, and Popliteus muscles ; the central portion is formed of fasciculi obliquely directed and separated from one another by apertures for the passage of vessels. The strongest of these fasciculi is derived from the tendon of the Semimembranosus ; it passes from the back part of the inner tuberosity of the tibia, obliquely upAvards and outAvards to the back part of the outer condyle of the femur. The posterior ligament forms part of the floor of the popliteal space, and upon it rests the popliteal artery. The Internal Lateral Ligament is a broad, flat, membranous band, thicker behind than in front, and situated nearer to the back than the front of the joint. It is attached, above, to the inner tuberosity of the femur; beloAV, to the inner tuberosity and inner surface of the shaft of the tibia, to the extent of about two inches. It is crossed, at its lower part, by the aponeurosis of the Sartorius, and the tendons of the Gracilis and Semitendinosus muscles, a synovial bursa being interposed. Its deep surface covers the anterior portion of the tendon of 174 ARTICULATIONS. the Semimembranosus, the synovial membrane of the joint, and the inferior inter- nal articular artery; it is intimately adherent to the internal semilunar fibro- cartilage. The Long External Lateral Ligament is a strong, rounded, fibrous cord, situated nearer the posterior part of the articulation than the anterior. It is attached, above, to the outer tuberosity of the femur; below, to the outer part of the head of the fibula. Its outer surface is covered by the tendon of the Biceps, which divides into two parts, separated by this ligament, at its insertion. It has passing beneath it, the tendon of the Popliteus muscle, and the inferior external articular artery. The Short External Lateral Ligament is an accessory bundle of fibres, placed behind and parallel with the preceding; attached, above, to the lower part of the outer tuberosity of the femur; beloAv, to the summit of the styloid process of the fibula. This ligament is intimately connected with the capsular ligament, and has passing beneath it the tendon of the Popliteus muscle. The Capsular Ligament consists of an exceedingly thin, but strong, fibrous membrane, Avhich surrounds the joint in the intervals left by the preceding liga- ments, being attached to the femur immediately above its articular surface; below, to the upper border and sides of the patellae, the margins of the head of the tibia and interarticular cartilages, and being continuous behind Avith the pos- terior ligament. This membrane is strengthened by fibrous expansions, derived from the fascia lata and Vasti muscles, at their insertion into the sides of the patella. The Crucial are two interosseous ligaments of very considerable strength, situated in the interior of the joint, nearer its posterior than its anterior part. They are called crucial, because they cross each other, somewhat like the lines of Fig. 124.—Right Knee Joint. Showing Internal Ligaments. F e S U PER '0« Tie iv • riSULAR ART1C KNEE JOINT. 175 Fig. 125.—Head of Tibia, with Semilunar Cartilages, etc. Seen from above. Right Side. the letter X ; and have received the names anterior and posterior, from the posi- tion of their attachment to the tibia. The Anterior or External Crucial Ligament (Fig. 124), smaller than the poste- rior, arises from the inner side of the depression in front of the spine of the tibia being blended Avith the anterior extremity of the external semilunar fibro-carti- lage, and passing obliquely upwards, backwards, and outwards, is inserted into the inner and back part of the outer condyle of the femur. The Posterior or Interned Crucial Ligament is larger in size, but less oblique in its direction than the anterior. It arises from the back part of the depression behind the spine of the tibia, and from the posterior extremity of the external semilunar fibro-cartilage ; passing upwards, forwards, and inwards, it is inserted into the outer and front part of the inner condyle of the femur. As it crosses the anterior crucial ligament, a fasciculus is given off from it, which blends with its posterior part. It is in relation, in front, with the anterior ligament; behind, with the ligamentum posticum Winslowii. The Semilunar Fibro-cartilages (Fig. 125) are two crescentic lamellae attached to the margins of the head of the tibia, serving to deepen its surface for articula- tion Avith the condyles of the femur. The circumference of each cartilage is thick and convex ; the inner free border, thin and con- cave. Their upper surfaces are concave, and in relation Avith the condyles of the femur ; their loAver surfaces are flat, and rest upon the head of the tibia. Each cartilage covers nearly the outer tAvo-thirds of the corre- sponding articular surface of the tibia, the inner third being uncovered; both surfaces are smooth, and invested by synovial mem- brane. The Internal Semilunar Fibro-cartilage is nearly semicircular in form, a little elon- gated from before backAvards, and broader behind than in front; its convex border is united to the internal lateral ligament, and to the head of the tibia, by means of the coronary ligaments ; its anterior extremity, thin and pointed, is firmly im- planted into the depression in front of the spine of the tibia; its posterior extre- mity to the depression behind the spine. The External Semilunar Fibro-cartilage forms nearly an entire circle, cover- ing a larger portion of the articular surface than the internal one. It is grooved on its outer side, for the tendon of the Popliteus muscle. Its circumference is held in connection Avith the head of the tibia, by means of the coronary ligaments ; and by its OAvn extremities is firmly implanted in the depressions in front and behind the spine of the tibia. These extremities, at their insertion, are interposed betAveen the attachments of the internal cartilage. The external semilunar fibro- cartilage gives off from its anterior border a fasciculus, which forms the trans- verse ligament. By its anterior extremity, it is continuous Avith the anterior crucial ligament. Its posterior extremity divides into three slips; one, a strong cord, passes upAvards and forwards, and is inserted into the outer side of the inner condyle, in front of the posterior crucial ligament; another fasciculus is inserted into the outer side of the inner condyle, behind the posterior crucial ligament; a third fasciculus is inserted into the back part of the anterior crucial ligament. The Transverse Ligament is a band of fibres, which passes transversely between the anterior convex margin of the external cartilage, to the anterior extremity of the internal cartilage; its thickness varies considerably in different subjects. The Coronary Ligaments consist of numerous short fibrous bands, which con- nect the convex border of the semilunar cartilages with the circumference of the head of the tibia, and with the other ligaments surrounding the joint. V *,-*/' 176 ARTICULATIONS. The Synovial Membrane of the knee joint is the largest and most extensive in the body. Commencing at the upper border of the patella, it forms a large cul- de-sac beneath the Extensor tendon of the thigh: this is sometimes replaced by a synoAnal bursa interposed betAveen this tendon and the femur, which in some subjects communicates with the synovial membrane of the knee joint, by an orifice of variable size. On each side of the patella, the synovial membrane extends beneath the aponeuroses of the Vasti muscles, and more^ especially beneath that of the Vastus internus ; it covers the surface of the patella itself, and, beneath it, is separated from the anterior ligament by a considerable quantity of adipose tissue. In this situation, it sends off a triangular-shaped prolongation, containing a few ligamentous fibres, which extends from the anterior part of the joint below the patella, to the front of the intercondyloid notch. Tim fold has been termed the ligamentum mucosum. The ligamenta alaria consist of two fringe-like folds, which extend from the sides of the ligamentum mucosum, upwards and out- Avards, to the sides of the patella. The synovial membrane covers both surfaces of the semilunar fibro-cartilages, and on the back part of the external one forms a cul-de-sac between the groove on its surface and the tendon "of the Popliteus; it covers the articular surface of the tibia ; surrounds the crucial ligaments, and inner surface of the ligaments which inclose the joint; lastly, it covers the entire surface of the condyles of the femur, and from them is continued on to the lower part of the front surface of the shaft. The pouch of synovial membrane between the Extensor tendons and front of the femur is supported, during the movements of the knee, by a small muscle, the Subcrurseus, which is inserted into it. The Arteries supplying this joint are derived from the anastomotic branch of the Femoral, articular branches of the Popliteal, and recurrent branch of the An- terior Tibial. The nerves are derived from the obturator and external and internal popliteal. Actions. The chief movements of this joint are flexion and extension; but it is also capable of performing some slight rotatory movement. During flexion, the articular surfaces of the tibia, covered by their interarticular cartilages, glide backwards upon the condyles of the femur, the lateral posterior and crucial liga- ments are relaxed, the ligamentum patellae is put upon the stretch, the patella filling up the vacuity in the front of the joint betAveen the femur and tibia. In extension, the tibia and interarticular cartilages glide forAvards upon the femur; all the ligaments are stretched, Avith the exception of the ligamentum patellae, Avhich is relaxed, and admits of considerable lateral movement. The movement of rotation is permitted Avhen the knee is semiflexed, rotation outAvards being most extensive. 3. Articulations between the Tibia and Fibula. The articulations between the tibia and fibula are effected by ligaments Avhich connect both extremities, as well as the centre of these bones. They may, conse- quently, be subdivided into three sets. 1. The Superior Tibio-fibular articula- tion. "2. The Middle Tibio-fibular articulation. 3. The Inferior Tibio-fibular articulation. (1.) Superior Tibio-fibular Articulation. This articulation is an arthrodial joint. The contiguous surfaces of the bones present two flat, oval surfaces, covered Avith cartilage, and connected together by the following ligaments. Anterior Superior Tibio-fibular. Posterior Superior Tibio-fibular. Synovial Membrane. The Anterior Superior Ligament (Fig. 124) consists of tAvo or three broad and flat bands, which pass obliquely upAvards and inwards, from the head of the fibula to the outer tuberosity of the tibia. TIBIO-FIBULAR. 177 The Posterior Superior Ligament is a single, thick, and broad band, Avhich passes from the back part of the head of the fibula to the back part of the outer tuberosity of the tibia. It is covered in by the tendon of the Popliteus muscle. There is a distinct Synovud Membrane in this articulation. Occasionally, the synovial membrane of the knee joint is continuous Avith it at its upper and back part. (2.) Middle Tibio-fibular Articulation. The interval betAveen the tibia and fibula is filled up by an interosseous mem- brane, which extends betAveen the contiguous margins of the tAvo bones. It consists of a thin aponeurotic lamina, composed of oblique fibres, which pass between the interosseous ridges on the tibia and fibula. It is broader above than beloiv, and presents at its upper part a large oval aperture for the passage of the anterior tibial artery forAvards to the anterior aspect of the leg; and at its lower third, another opening, for the passage of the anterior peroneal vessels. It is continuous below Avith the inferior interosseous ligament; and is perforated in numerous parts for the passage of small vessels. By its anterior surface it is in relation with the Tibialis anticus, Extensor longus digitorum, Extensor proprius pollicis, Peroneus tertius, and the anterior tibial vessels and nerve; behind, with the Tibialis posticus and Flexor longus pollicis muscles. (3.) Inferior Tibio-fibular Articulation. This articulation, continuous with that of the ankle joint, is formed by the convex surface at the lower end of the inner side of the fibula, being received into a concave surface on the outer side of the tibia. These surfaces below, to the extent of about tAvo lines, are smooth and covered Avith cartilage, Avhich is continuous with that of the ankle joint. Its ligaments are— Inferior Interosseous. Posterior Inferior Tibio-fibular. Anterior Inferior Tibio-fibular. Transverse. The Inferior Interosseous Ligament consists of numerous short, strong fibrous bands, which pass betAveen the contiguous rough surfaces of the tibia and fibula, constituting the chief bond of union between these bones. It is continuous, above, Avith the interosseous membrane. The Anterior Lnferior Ligament (Fig. 127) is a flat triangular band of fibres, broader below than above, Avhich extends obliquely dowmvards and outAvards be- tween the adjacent margins of the tibia and fibula on the front aspect of the articulation. It is in relation, in front, Avith the Peroneus tertius, the aponeurosis of the leg, and the integument; behind, with the inferior interosseous ligament, and lies in contact Avith the cartilage covering the astragalus. _ The Posterior Inferior Ligament, smaller than the preceding, is disposed in a similar manner on the posterior surface of the articulation. The Transverse Ligament is a long, narroAv band of ligamentous fibres, continu- ous with the preceding, passing transversely across the back of the joint, from the external malleolus to the tibia, a short distance from its malleolar process. The three preceding ligaments project somewhat beloAV the margins of the bones, and form part of the articulating surface for the ankle joint. The Synovial Membrane lining the articular surfaces is derived from that of the ankle joint. Actions^ The movement permitted in these articulations is limited to a very slight gliding of the articular surfaces upon one another. 14 178 ARTICULATIONS. (4.) Ankle Joint. The Ankle is a ginglymoid or hinge joint. The bones entering into its forma- tion are the loAver extremity of the tibia and its malleolus, and the malleolus of the fibula, above; which, united, form an arch, in Avhich is received the upper convex surface of the astragalus and its two lateral facets. These surfaces are covered with cartilage, lined by synovial membrane, and connected together by the folloAving ligaments :— Anterior. Internal Lateral. External Lateral. The Anterior Ligament (Fig. 126) is a broad, thin, membranous layer, attached above, to the margin of the articular surface of the tibia; beloAV, to the margin of the astragalus, in front of its articular surface. It is in relation, in front, with Fig. 126.—Ankle Joint: Tarsal and Tarso-metatarsal Articulations. Internal View. Right Side. the extensor tendons of the toes, the tendons of the Tibialis anticus and Peroneus tertius, and the anterior tibial vessels and neiwe; posteriorly, it lies in contact with the synovial membrane. The Internal Lateral or Deltoid Ligament consists of two layers, superficial and deep. The superficial layer is a strong, flat, triangular band, attached, above, to the apex and anterior and posterior border of the inner malleolus. The most anterior fibres pass forAvards to be inserted into the scaphoid; the middle descend almost perpendicularly to be inserted into the os ealcis; and the posterior fibres pass backAvards and outAvards to be attached to the inner side of the astragalus. The deeper layer consists of a short, thick, and strong fasciculus, which passes from the apex of the malleolus to the inner surface of the astragalus, below the articular surface. This ligament is covered in by the tendons of the Tibialis pos- ticus and Flexor longus digitorum muscles. ANKLE JOINT. 179 The External Lateral Ligament (Fig. 127) consists of three fasciculi, taking different directions, and separated by distinct intervals. The anterior fasciculus, the shortest of the three, passes from the anterior mar- gin of the summit of the external malleolus, doAvnwards and forwards, to the astra- galus, in front of its external articular facet. The posterior fasciculus, the most deeply seated, passes from the depression at the inner and back part of the external malleolus to the astragalus, behind its external malleolar facet. Its fibres are directed obliquely doAviiAvards and in- wards. The middle fasciculus, the longest of the three, is a narrow, rounded cord, pass- ing from the apex of the external malleolus downwards and slightly backwards to the middle of the outer side of the os ealcis. It is covered by the tendons of the Peroneus longus and brevis. There is no posterior ligament, its place being sup- plied by the transverse ligament of the tibia and fibula. The Synovial Membrane invests the cartilaginous surfaces of the tibia and fibula, Fig. 127.—Ankle Joint: Tarsal and Tarsometatarsal Articulations. External View. Right Side. and sends a duplicature upAvards betAveen their lower extremities; it is then re- flected on the inner surface of the ligaments surrounding the joint, and covers the upper surface of the astragalus and its tAvo lateral facets beloAV. Relations. The tendons, vessels, and nerves in connection with this joint are, in front, from Avithin outAvards, the Tibialis anticus, Extensor proprius pollicis, anterior tibial vessels, anterior tibial nerve, Extensor communis digitorum, and Peroneus tertius; behind, from Avithin outwards, Tibialis posticus, Flexor longus digitorum, posterior tibial vessels, posterior tibial nerve, Flexor longus pollicis, and, in the groove behind the external malleolus, the tendons of the Peroneus longus and brevis. The Arteries supplying the joint are derived from the malleolar branches of the anterior tibial and peroneal. The Nerves are derived from the anterior tibial. Actions. The movements of this joint are limited to flexion and extension. There ■s no lateral motion. 180 ARTICULATIONS. 5. Articulations of the Tarsus. These articulations may be subdivided into three sets : 1. The articulation of the first row of tarsal bones. 2. The articulation of the second i*oav of tarsal bones. 3. The articulation of the tAvo roAvs with each other. (1.) Articulation of the First Roav of Tarsal Bones. The articulation betAveen the astragalus and os ealcis is an arthrodial joint, con- nected together by three ligaments. External Calcaneo-astragaloid. Interosseous. Posterior Calcaneo-astragaloid. Tavo Synovial Membranes. The External Calcaneo-astragaloid Ligament (Fig. 127) is a short, strong fasci- culus, passing from the outer surface of the astragalus, immediately beneath its external malleolar facet, to the outer edge of the os ealcis. It is placed in front of the middle fasciculus of the external lateral ligament of the ankle joint, with the fibres of Avhich it is parallel. The Posterior Calcaneo-astragaloid Ligament (Fig. 12G) connects the posterior extremity of the astragalus with the upper contiguous surface of the os ealcis; it is a short narrow band, the fibres of which are directed obliquely backAvards and inAvards. The Interosseous Ligament forms the chief bond of union betAveen these bones. It consists of numerous vertical and oblique fibres, attached by one extremity to the groove betAveen the articulating surfaces of the astragalus;' by the other, to a corresponding depression on the upper surface of the os ealcis. It is very thick and strong, being at least an inch in breadth from side to side, and serves to unite the os ealcis and astragalus solidly together. The Synovial Membranes (Fig. 12(J) are tAvo in number ; one for the posterior calcaneo-astragaloid articulation, a second for the anterior calcaneo-astragaloid joint. The latter synovial membrane is continued forAvards between the contiguous surfaces of the astragalus and scaphoid bones. (2.) Articulations of the Second Roav of Tarsal Bones. The articulations between the scaphoid, cuboid, and three cuneiform, are effected by the folloAving ligaments :— Dorsal. Plantar. Interosseous. The Dorsal Ligaments are small bands of parallel fibres, which pass from each bone to the neighboring bones with which it articulates. The Plantar Ligaments have the same arrangement on the plantar surface. The Interosseous Ligaments are four in number. They consist of strong trans- verse fibres, which pass betAveen the rough non-articular surfaces of adjoining bones. There is one between the sides of the scaphoid and cuboid, a second be- tAveen the internal and middle cuneiform bones, a third betAveen the middle and external cuneiform, and a fourth between the external cuneiform and cuboid. The scaphoid and cuboid, Avhen in contact, present each a small articulating facet, covered with cartilage, and lined either by a separate synovial membrane, or by an offset from the common tarsal synovial membrane. (3.) Articulations of the Two Rows of the Tarsus avith each other. These articulations consist of ligaments that may be conveniently divided into OF THE TARSUS. LSI three sets. 1. The articulation of the os ealcis with the cuboid. 2. The os ealcis with the scaphoid. 3. The astragalus with the scaphoid. 1. The ligaments connecting the os ealcis with the cuboid are four in number. Dorsal. Fig. 128.—Ligaments of Plantar Surface of the Foot. f Superior Calcaneo-cuboid. \ Internal Calcaneo-cuboid (Interosseous). Plantar i ^0ng (,alcane°-CUDoid. \ Short Calcaneo-cuboid. Synovial Membrane. The Superior Cedcaneo-cuboid Ligament (Fig. 127) is a thin and narrow fasciculus, Avhich passes betAveen the contiguous surfaces of the os ealcis and cuboid, on the dorsal surface of the joint. The Internal Calcaneo-cuboid (Interosseous) Ligament (Fig. 127) is a short, but thick and strong, band of fibres, arising from the os ealcis, in the deep groove which intervenes betAveen it and the astragalus; being closely blended, at its origin, with the superior calcaneo-scaphoid ligament. It is inserted into the inner side of the cuboid bone. This ligament forms one of the chief bonds of union betAveen the first and second i-oavs of the tarsus. The Long Cedcaneo-cuboid (Fig. 128), the most superficial of the tAvo plantar ligaments, is the longest of all the liga- ments of the tarsus, being attached pos- teriorly to the under surface of the os ealcis, as far forAvards as the anterior tubercle, and passing horizontally for- wards to the tuberosity on the under surface of the cuboid bone, the more superficial fibres being continued for- wards to the bases of the second, third, and fourth metatarsal bones. This liga- ment crosses the groove on the under surface of the cuboid bone, converting it into a canal for the passage of the ten- don of the Peroneus longus. The Short Calcaneo-cuboid'liesnearer to the bones than the preceding, from which it is separated by a little areolar adipose tissue. It is exceedingly broad, and about an inch in length ; passing from the tuberosity at the fore part of the under surface of the os ealcis, to the inferior surface of the cuboid bone be- hind the peroneal groove. A synoA'ial membrane lines the contiguous surfaces of the bones, and is reflected upon the ligaments connecting them. 2. The ligaments connecting the os ealcis with the scaphoid are tAvo in num- ber. Superior Calcaneo-scaphoid. Inferior Calcaneo-scaphoid. Synovial Membrane. The Superior Cedcaneo-scaphoid arises (Fig. 127) as already mentioned, Avith the internal calcaneo-cuboid, in the deep groove betAveen the astragalus and os ealcis ; it passes forward from the inner side of the anterior extremity of the os ealcis to the outer side of the scaphoid \ 182 ARTICULATIONS. bone. These tAvo ligaments resemble the letter Y, being blended together behind, but separated in front. The Inferior Cedcaneo-scaphoid (Fig. 128) is by far the largest and strongest of the two ligaments of this articulation; it is a broad and thick band of ligamentous fibres, Avhich passes forwards and inAvards from the anterior and inner extremity of the os ealcis, to the under surface of the scaphoid bone. This ligament not only serves to connect the os ealcis and scaphoid, but supports the head of the astra- galus, forming part of the articular cavity in Avhich it is received. Its upper surface is lined by the synovial membrane continued from the anterior calcaneo- astragaloid articulation. Its under surface is in contact Avith the tendon of the Tibialis posticus muscle. 3. The articulation betAveen the astragalus and scaphoid is an enarthrodial joint; the rounded head of the astragalus being received into the concavity formed by the posterior surface of the scaphoid, the anterior articulating surface of the calcaneum, and the upper surface of the calcaneo-scaphoid ligament, Avhieh fills up the triangular interval betAveen these bones. The only ligament of this joint is the superior astragalo-scaphoid, a broad band of ligamentous fibres, which passes obliquely forAvards from the neck of the astragalus, to the superior surface of the scaphoid bone. It is thin and Aveak in texture, and covered by the Extensor tendons. The inferior calcaneo-scaphoid supplies the place of an inferior liga- ment. The Synovial Membrane Avhich lines this joint is continued forAvards from the anterior calcaneo-astragaloid articulation. This articulation permits of considerable mobility ; but its feebleness is such as to occasionally allow of dislocation of the astragalus. The Synovial Membranes (Fig. 129) found in the articulations of the tarsus are Fig. 129.—Oblique Section of the Articulations of the Tarsus aud Metatarsus. Showing the Six Synovial Membranes. four in number : one for the posterior calcaneo-astragaloid articulation ; a second for the anterior calcaneo-astragaloid and astragalo-scaphoid articulations; a third for the calcaneo-cuboid articulation ; and a fourth for the articulations between the scaphoid and the three cuneiform, the three cuneiform with each other, the external cuneiform with the cuboid, and the middle and external cuneiform with the bases of the second and third metatarsal bones. The prolongation which lines the metatarsal bones passes forward be'tween the external and middle cuneiform bones. A small synovial membrane is sometimes found BetAveen the contiguous surfaces of the scaphoid and cuboid bones. Actions. The movements permitted between the bones of the first row, the TARSO-METATARSAL. 183 astragalus, and os ealcis, are limited to a gliding upon each other from before backwards, and from side to side. The gliding movement Avhich takes place between the bones of the second toav, is very slight, the articulation betAveen the scaphoid and cuneiform bones being more movable than those of the cuneiform with each other, and with the cuboid. The movement Avhich takes place betAveen the two rows is more extensive, and consists in a sort of rotation, by means of Avhich the sole of the foot may be slightly flexed and extended, or carried inAvards and outwards. 6. Tarso-metatarsal Articulations. These are arthrodial joints. The bones entering into their formation are the internal, middle, external cuneiform, and cuboid, which articulate Avith the meta- tarsal bones of the five toes. The metatarsal bone of the first toe articulates with the internal cuneiform; that of the second is deeply Avedged in betAveen the internal and external cuneiform, resting against the middle cuneiform, and being the most strongly articulated of all the metatarsal bones; the third metatarsal articulates Avith the extremity of the external cuneiform; the fourth, with the cuboid and external cuneiform; and the fifth Avith the cuboid. These various articular surfaces are covered Avith cartilage, lined by synovial membrane, and connected together by the folloAving ligaments :— Dorsal. Plantar. Interosseous. The Dorsal Ligaments consist of strong, flat, fibrous bands, Avhich connect the tarsal with the metatarsal bones. The first metatarsal is connected to the inter- nal cuneiform by a single, broad, thin, fibrous band; the second has three dorsal ligaments, one from each cuneiform bone; the third has one from the external cuneiform; and the fourth and fifth have one each from the cuboid. The Plantar Ligaments consist of strong fibrous bands connecting the tarsal and metatarsal bones, but disposed with less regularity than on the dorsal surface. Those for the first and second metatarsal are the most strongly marked; the second and third receive strong fibrous bands, Avhich pass obliquely across from the internal cuneiform; the plantar ligaments of the fourth and fifth consist of a few scanty fibres derived from the cuboid. The Interosseous Ligaments are three in number : internal, middle, and external. The internal one passes from the outer extremity of the internal cuneiform to the adjacent angle of the second metatarsal. The middle one, less strong than the preceding, connects the external cuneiform Avith the adjacent angle of the second metatarsal. The external interosseous ligament connects the outer angle of the external cuneiform Avith the adjacent side of the third metatarsal. The Synovial Membranes of these articulations are three in number: one for the metatarsal bone of the great toe, Avith the internal cuneiform: one for the second and third metatarsal bones, Avith the middle and external cuneiform: this is con- tinuous Avith the great tarsal synovial membrane ; and one for the fourth and fifth metatarsal bones Avith the cuboid. The synovial membranes of the tarsus and metatarsus are thus seen to be six in number (Fig. 129). Articulations of the Metatarsal Bones avith each other. At their tarsal extremities, the metatarsal bones are connected together by dorsal, plantar, and interosseous ligaments. The dorsal anil plantar ligaments pass from one metatarsal bone to another. The interosseous ligaments lie deeply betAveen the rough non-articular portions of their lateral surfaces. The articular surfaces are covered by synovial membrane, continued forAvards from their respective tarsal joints. At their digital extremities they are connected to each other by the trans- verse metatarsal ligament, Avhich holds them loosely together. This ligament, which is analogous to the same structure in the hand, connects the great toe with the rest of the metatarsal bones, which in this respect differs from the same structure in the hand. 181 ARTICULATIONS. Actions. The movement permitted in the tarsal ends of the metatarsal bones is limited to a slight gliding of the articular surfaces upon one another; considerable motion, hoAvever, takes place in their digital extremities. Metatarsal-phalangeal Articulations. The heads of the metatarsal bones are connected with the concave articular surfaces of the first phalanges by the following ligaments:— Anterior or Plantar. Tavo Lateral. Synovial Membrane. They are arranged precisely similar to the corresponding parts in the hand. The expansion of the Extensor tendon supplies the place of a posterior ligament. Actions. The movements permitted in the metatarso-phalangeal articulations are flexion, extension, abduction, and adduction. Articulation of the Phalanges. The ligaments of these articulations are similar to those found in the hand; each pair of phalanges being connected by an anterior or plantar or tAvo lateral liga- ments, and their articular surfaces lined by synovial membrane. Their actions are also similar. s The Muscles and Fasciae, rpiIE Muscles and Fasciae are described conjointly, in order that the student may ■*- consider the arrangement of the latter in his dissection of the former. It is rare for the student of anatomy in this country to have the opportunity of dissect- ing the fasciae separately ; and it is from this reason, as well as from the close connection that exists betAveen the muscles and their investing aponeuroses, that they are considered together. Some general observations are first made on the anatomy of the muscles and fascia, the special description being given in connec- tion with the different regions. The Muscles are the active organs of locomotion. They are formed of bundles of reddish fibres, consisting chemically of fibrin, and endoAved Avith the property of contractility. Muscle is of a deep red color, the intensity of which varies considerably Avith the age and health of the individual. It is composed of bundles of parallel fibres, placed side by side, and connected together by a delicate Aveb of areolar tissue. Each fasciculus consists of numerous smaller bundles, and these of single fibres, which, from their minute size, and comparatively isolated appearance, have been called ultimate fibres. Two kinds of ultimate muscular fibre are found in the ani- mal body, viz., that of voluntary or animal life, and that of involuntary or organic life. The ultimate fibre of animal life is capable of being either excited or con- trolled by the efforts of the Avill; and is characterized, on microscopic examination, by its size, its uniform calibre, and the presence of minute transverse bars, Avhich are situated at short and regular distances throughout its Avhole extent. Of such is composed the muscular tissue of the trunk and limbs, the fibres of the heart, and some of those of the oesophagus : the muscles of the internal ear, and those of the urethra, present a similar structure, although they are not capable of being acted upon by the will. Involuntary muscular fibre is entirely AvithdraAvn from the influ- ence of volition, and is characterized, on microscopic examination, by the ultimate fibrils being homogeneous in structure, of smaller size than those of animal life, flattened, and unstriped ; of such the muscles of the digestive canal, the bladder, and uterus are composed. Each muscle is invested externally by a thin cellular layer, forming Avhat is called its sheath, which not only covers its outer surface, but penetrates info its interior in the intervals betAveen the fasciculi, surrounding these, and serving as a bond of connection betAveen them. The voluntary muscular fibres terminate at either extremity in fibrous tissue, the separate fibrillae of which being, in some cases, aggregated together, form a rounded or flattened fibrous cord or tendon; in the flat muscles, the separate fibres are arranged in flattened membranous laminae, termed aponeuroses; and it is in one or other of these forms that nearly every muscle is attached' to the part which it is destined to move. The involuntary muscular fibres, on the contrary, form a dense interlacement, crossing each other at various angles, forming a layer of variable thickness, Avhich usually circumscribes the Avail of some cavity, which, by its contraction, it con- stricts. Muscles vary considerably in their form. In the limbs, they are of considerable length, especially the more superficial ones, the deep ones being generally broad; they surround the bones, and form an important protection to the various joints. In the trunk, they are broad, flattened, and expanded, forming the parietes of the cavities Avhich they inclose ; hence the reason of the terms, long, broad, short, etc., used in the description of a muscle. There is considerable variation in the arrangement of the fibres of certain muscles, in relation to the tendon to which they are attached. In some, the fibres 18G MUSCLES AND FASCRE. are arranged longitudinally, and terminate at either end in a narrow tendon so that the muscle is broad at the centre, and narroAved at either extremity : such a muscle is said to he fusiform in shape, as the Rectus femoris. If the fibres con- verge, like the plumes of a pen, to one side of a tendon, Avhich runs the entire length of the muscle, it is said to be penniform, as the Peronei; or, if thev con- verge to both sides of a tendon, they are called bipenniform, as the Rectus femoris- if they converge from a broad surface to a narroAv, tendinous point, they are then said to be radiated, as the Temporal and Glutaei muscles. Their size presents considerable variation : the Gastrocnemius forms the chief bulk of the back of the leg, and the fibres of the Sartorius are nearly tAvo feet in length, whilst the Stapedius, a small muscle of the internal ear, Aveighs about a grain, and its fibres are not more than two lines in length. In each case, hoAvever they are admirably adapted to execute the various movements they are required to perform. The names applied to the various muscles have been derived : 1, from their situa- tion, as the Tibialis, Radialis, Ulnaris, Peroneus; 2, from their direction, as the Rectus abdominis, Obliqui capitis, Transversalis; 3, from their uses, as Flexors, Extensors, Abductors, etc.; 1, from their shape, as the Deltoid, Trapezius, Rhom- boideus; 5, from the number of their divisions, as the Biceps (from having two heads), the Triceps (from having three heads); 6, from their points of attachment, as the Sterno-cleido-mastoid, Sterno-hyoid, Sterno-thyroid. In the description of a muscle, the term origin is meant to imply its more fixed or central attachment; and the term insertion, the movable point upon Avhich the force of the muscle is directed : this holds true, hoAvever, for only a very small number of muscles, such as those of the face, Avhich are attached by one extremity to the bone, and by the other to the movable integument; in the greater number, the muscle can be made to act from either extremity. In the dissection of the muscles, the student should pay especial attention to the exact origin, insertion, and actions of each, and its more important relations with surrounding parts. An accurate knowledge of the points of attachment of the muscles is of great importance in the determination of their action. By a knowledge of the action of the muscles, the surgeon is able at once to explain the causes of displacement in the various forms of fracture, or the causes which pro- duce distortion in various forms of deformities, and, consequently, to adopt appro- priate treatment in each case. The relations, also, of some of the muscles, especially those in immediate apposition with the larger bloodvessels, and the surface-mark- ings they produce, should be especially remembered, as they form most useful guides to the surgeon in the application of a ligature to these vessels. The Fasciae (fascia, a bandage) are fibro-areolar or aponeurotic lamina?, of vari- able thickness and strength, found in all regions of the body, investing the softer and more delicate organs. The fasciae have been subdivided, from the structure which they present, into two groups, fibro-areolar or superficial fascia?, and aponeu- rotic or deep fasciae. The fibro-areolar fascia is found immediately beneath the integument, over almost the entire surface of the body, and is generally known as the superficial fascia. It connects the skin Avith the deep or aponeurotic fascia, and consists of fibro-areolar tissue, containing in its meshes pellicles of fat in varying quantity. In the eyelids and scrotum, Avhere adipose tissue is never deposited, this tissue is very liable to serous infiltration. This fascia varies in thickness in different parts of the body: in the groin it is so thick as to be capable of being subdivided into several laminae; but in the palms of the hands it is of extreme thinness, and inti- mately adherent to the integument. The superficial fascia is capable of separation into two or more layers, betAveen Avhich are found the superficial vessels and nerves. and superficial lymphatic glands, as the superficial epigastric vessels in the ab- dominal region, the radial and ulnar veins in the forearm, the saphenous veins in the leg and thigh, as well as in certain situations cutaneous muscles, as the Platysma myoides in the neck, Orbicularis palpebrarum around the eyelids. It is GENERAL ANATOMY. is; most distinct at the loAver part of the abdomen, the scrotum, perinseum, and in the extremities; is very thin in those regions where muscular fibres are inserted into the integument, as on the side of the neck, the face, and around the margin of the anus, and almost entirely Avanting in the palms of the hands and soles of the feet. where the integument is adherent in the subjacent aponeurosis. The superficial fascia connects the skin to the subjacent parts, serves as a soft nidus for the pas- sage of vessels and nerves to the integuments, and retains the Avarmth of the body, from the adipose tissue contained in its areola? being a bad conductor of caloric/ The aponeurotic or deep fascia is a dense, inelastic and unyielding fibrous membrane, forming sheaths for the muscles, and affording them broad surfaces for attachment; it consists of shining tendinous fibres, placed parallel Avith one another, and connected together by other fibres disposed in a reticular manner. It is usu- ally exposed on the removal of the superficial fascia, forming a strong investment, which not only binds down collectively the muscles in each region, but gives a separate sheath to each, as Avell as to the vessels and nerves. The fascia? are thick in unprotected situations, as on the outer side of a limb, and thinner on the inner side. By Bichat, aponeurotic fascia? Avere divided into tAvo classes, aponeurosis of insertion, and aponeurosis of investment. The aponeuroses of insertion serve for the insertion of muscles. Some of these are. formed by the expansion of a tendon into an aponeurosis, as, for instance, the tendon of the Sartorius; others do not originate in tendons, as the aponeuroses of the abdominal muscles. The aponeuroses of investment form a sheath for the entire limb, as Avell a-; for each individual muscle. Many aponeuroses, hoAvever, serve both for invest- ment and insertion. Thus the deep fascia on the front of the leg gives attachment to the muscles in this region; and the aponeurosis of insertion given off from the tendon of the Biceps is continuous with the investing fascia of the fore- arm, and gives origin to the muscles in this region. The deep fascia? assist the muscles in their action, by the degree of tension and pressure they make upon their surface; and in certain situations this is increased and regulated by muscular action, as, for instance, by the Tensor vaginae femoris and Glutaeus maximus in the thigh, by the Biceps in the leg, and Palmaris longus in the hand. In the limbs the fasciae not only invest the entire limb, but giA-e off septa, Avhich sepa- rate the various muscles, and are attached beneath to the periosteum; these pro- longations of fascia? are usually spoken of as intermuscular septa. The Muscles and Fascia? may be arranged, according to the general division of the body, into, 1. Those of the head, face, and neck. 2. Those of the trunk. 3. Those of the upper extremity. 4. Those of the lower extremity. MUSCLES AND FASCIAE OF THE HEAD AND FACE. The Muscles of the Head and Face consist of ten groups, arranged according to the region in which they are situated. 1. Cranial Region. 6. Superior Maxillary Region. 2. Auricular Region. 7. Inferior Maxillary Region. 3. Palpebral Region. 8. Intermaxillary Region. 1. Orbital Region. 9. Tempero-maxillary Region. 5. Nasal Region. 10. Pterygo-maxillary Region. The Muscles contained in each of these groups are the following :— 1. Epicranial Region. 3. Palpebral Region. Occipito-frontalis. Orbicularis palpebrarum. o . . 7 ,, . Corrugator supercilii. -. Auricular Ret/ion. m °, • 1 J Tensor tarsi. Attollens aurem. Attrahens aurem. 4- Orbital Region. Retrahens aurem. Levator palpebra?. 188 MUSCLES AND FASCRE. Rectus superior. Rectus inferior. Rectus internus. Rectus externus. Obliquus superior. Obliquus inferior. 5. Nasal Region. Pyramidalis nasi. Levator labii superioris ala?que nasi. Levator proprius ala? nasi posterior. Levator proprius alae nasi anterior. Compressor nasi. Compressor narium minor. Depressor alae nasi. 6. Superior Maxillary Region. Levator labii superioris proprius. Levator anguli oris. Zygomaticus major. Zygomaticus minor. 7. Inferior Jfaxillary Region. Levator labii inferioris. Depressor labii inferioris. Depressor anguli oris. 8. Intermaxillary Region. Buccinator. Risorius. Orbicularis oris. 9. Temporo-maxillary Region. Masseter. Temporal. 10. Pterygo-maxillary Region. Pterygoideus externus." Pterygoideus internus. 1. Epicranial Region—Occipito-frontalis. Dissection (Fig. 130). _ The head being shaved, and a block placed beneath the back of the neck, make a vertical incision through the skin from before backwards, commencing at the root ot the nose in front, and terminating behind at the occipital protuberance ; make a second incision in a horizontal direction along the forehead and around the side of the head, from Fig. 130.—Dissection of the Head, Face, and Neck. -1 iDisstction of sc tip he anterior to the posterior extremity of the preceding. Raise the skin in front from the subjacent muscle from below upwards; this must be done with extreme care, ou account ot their intimate union. The tendon of this muscle is best avoided by removing the in- tegument from the outer surface of the vessels and nerves which lie between the two. The superficial fascia in the epicranial region is a firm, dense layer, intimately acmerent to the integument, and to the Occipito-frontalis and its tendinous aponeu- rosis ; it is continuous, behind, with the superficial fascia at the back part of the necK , and laterally, is continued over the temporal aponeurosis : it contains be- tween its layers the small muscles of the auricle, and the superficial temporal vessels and nerves. ^ The Occipito-frontalis (Fig. 131) is a broad musculo-fibrous layer, which covers OCCIPITO-FRONTALIS. 189 over the Avhole of one side of the vertex of the skull, from the occiput to the eye- broAV. It consists of two muscular bellies, separated by an intervening tendinous aponeurosis. The occipital portion, thin, quadrilateral in form, and about an inch and a half in length, arises from the outer tAvo-thirds of the superior curved line of the occipital bone, and from the mastoid portion of the temporal. Its fibres of Fig. 131.—Muscles of the Head, Face, and Neck. ctmnucATOR DILATOR NAR'S AWTE D LATORNAHIS POSTCf CCHHIESSOflnMmiNMING! origin are tendinous, but they soon become muscular, and ascend in a parallel direction to terminate in the tendinous aponeurosis. The fronted portion is thin, of a quadrilateral form, and intimately adherent to the skin. It is broader, its fibres are longer, and their structure more pale than the occipital portion. Its internal fibres are continuous Avith those of the Pyramidalis nasi. Its middle n'nes become blended vsith the Corrugator supercilii and Orbicularis : and the 190 MUSCLES AND FASCRE. outer fibres are also blended Avith the latter muscle over the external aiuuilar process. The inner margins of the two frontal portions of the muscle are joined together for some distance above the root of the nose ; but betAveen the occipital portions there is. a considerable but variable interval. The aponeurosis covers over the AA'hole of the vertex of the skull without anv separation into tAvo lateral parts, and is connected with the occipital and frontal portions of the muscle. Behind, it is attached, in the interval betAveen the occi- pital origins, to the occipital protuberance, and superior curved lines above the attachment of the trapezius ; in front, it forms a short angular prolongation be- tAveen the frontal portions; and on each side, it has connected with it the Attollens and Attrahens aurem muscles : in this situation it loses its aponeurotic character and is continued over the temporal fascia to the zygoma by a layer of laminated areolar tissue. This aponeurosis is closely connected to the integument by a dense fibro-cellular tissue, Avhich contains much granular fat, and in which ramify the numerous vessels and nerves of the integument; it is loosely connected with the pericranium by a quantity of loose cellular tissue, which alloAvs of a considerable degree of movement of the integument. Nerves. The Occipito-frontalis is supplied (frontal portion) by the supraorbital and facial nerves; (occipital portion) by the posterior auricular branch of the facial and the small occipital. Actions. This muscle raises the eyebrows and the skin over the root of the nose; at the same time it throws the integument of the forehead into transverse wrinkles' a predominant expression in the emotions of delight. It also moves the scalp from before backwards, by bringing alternately into action the occipital and frontal portions. 2. Auricular Region (Fig. 131). Attollens Aurem. Attrahens Aurem. Retrahens Aurem. These three small muscles are placed immediately beneath the skin around the external ear. In man, in whom the external ear is almost immovable, they are rudimentary. They are the analogues of large and important muscles in some of the mammalia. Dissection. This requires considerable care, and should be performed in the following manner. To expose the Attollens aurem : draw the pinna or broad part of the ear down- wards, when a tense band will be felt beneath the skin, passing from the side of the head to the upper part of the concha • by dividing the skin over the tendon, in a direction from below upwards, and then reflecting it on each side, the muscle is exposed. To bring into view the Attrahens aurem, draw the helix backwards by means of a hook, when the muscle will be made tense, and may be exposed in a similar manner to the preceding. To expose the Retrahens aurem, draw the pinna forwards, when the muscle being made tense may be felt beneath the skin, at its insertion into the back part of the concha, and may be exposed in the same manner as the other muscles. The Attollens Aurem (superior auriculae), the largest of the three, is thin, and of a radiated form; it arises from the aponeurosis of the Occipito-frontalis, and is inserted by a thin, flattened tendon into the upper and anterior part of the concha. Relations. Externally, with the integument; internally, with the Temporal aponeurosis. The Attrahens Aurem (anterior auriculae), the smallest of the three, is of a triangular form, very thin in texture, and its fibres pale and indistinct. It arises from the lateral edge of the aponeurosis of the Occipito-frontalis ; its fibres con- verge to be inserted into the front of the helix. Relations. Externally with the skin; internally, with the temporal fascia, which separates it from the temporal artery and vein. The Retrahens Aurem (posterior auriculae) consists of two or three fleshy AURICULAR AND PALPEBRAL REGIONS. 191 fasciculi, which arise from the mastoid portion of the temporal bone by short aponeurotic fibres. They are inserted into the back part of the concha. Relations. Externally, Avith the integument; internally, with the mastoid portion of the temporal bone. Nerves. The Attollens aurem is supplied by the small occipital; the Attrahens aurem, by the facial and auriculotemporal branch of the inferior maxillary, and the Retrahens aurem, by the posterior auricular branch of the facial. Actions^ In man these muscles possess very little action; their use is sufficiently expressed in their names. 3. Palpebral Region (Fig. 131). Orbicularis Palpebrarum. Levator Palpebrse. Corrugator Supercilii. Tensor Tarsi. Dissection (Figs. 130-4). In order to expose the muscles of the face, continue the longitudinal incision made in the dissection of the Occipito-frontalis, down the median line of the face to the tip of the nose, and from this point onwards to the upper lip; another incision should be carried along the margin of the lip to the angle of the mouth, and transversely across the face to the angle of the jaw. The integument should also be divided by an incision made in front of the external ear, from the angle of the jaw, upwards, to the transverse incision made in exposing the Occipito-frontalis. These incisions include a square-shaped flap, which should be carefully removed in the direction marked in the figure, as the mus- cles at some points are intimately adherent to the integument. The Orbicularis Palpebrarum is a sphincter muscle Avhich surrounds the whole circumference of the orbit and eyelids. It arises from the internal angular process of the frontal bone, from the nasal process of the superior maxillary in front of the lachrymal groove, and from the anterior surface and borders of a short tendon, the Tendo palpebrarum, placed at the inner angle of the orbit. The muscle, thus arising, forms a broad, thin, and flat plane of elliptical fibres, which cover the eye- lids, surround the circumference of the orbit, and spread out over the temple, and downwards on the cheek, becoming blended with the Occipito-frontalis and Corru- gator supercilii. The palpebral portion (ciliaris) of the Orbicularis is thin and pale; it arises from the bifurcation of the tendo palpebrarum, and forms a series of concentric curves, which are united on the outer side of the eyelids at an acute angle by a cellular raphe, some being inserted into the external tarsal ligament and malar bone. The orbicular portion (orbicularis latus) is thicker, of a reddish color, its fibres Avell developed, forming a complete ellipse. The tendro palpebrarum (oculi) is a short tendon, about tAvo lines in length and one in breadth, attached to the' nasal process of the superior maxillary bone anterior to the lachrymal groove. Crossing the lachrymal sac, it divides into two parts, each division being attached to the inner extremity of the corresponding tarsal cartilage. As the tendon crosses the lachrymal sac, a strong aponeurotic lamina is given off from its posterior surface, which expands over the sac, and is attached to the ridge on the lachrymal bone. This is the reflected aponeurosis of the lendo palpebrarum. Relations. By its superficial surface, the orbicular portion is closely adherent to the integument, more especially over the upper segment of the muscle; the palpe- bral portion being separated from the skin by loose areolar tissue. By its deep surface, above, with the Occipito-frontalis and Corrugator supercilii, with Avhich it is intimately blended, and Avith the supraorbital vessels and nerve; below, it covers the lachrymal sac and the origin of the Levator labii superioris, Levator labii superioris alaeque nasi, and the Zygomaticus major and minor muscles. internally, it is occasionally blended with the Pyramidalis nasi. Externally, it lies on the temporal fascia. On the eyelids, it is separated from the conjunctiva by a norous membrane and the tarsal cartilages. . The Corrugator Supercilii is a small, narrow, pyramidal muscle, placed at the mner extremity of the eyebrow, beneath the Occipito-frontalis and Orbicularis 192 MUSCLES AND FASCIA. palpebrarum muscles. It arises from the inner extremity of the superciliary ridge: its fibres pass upAvards and outAvards, to be inserted into the under surface of the orbicularis, opposite the middle of the orbital arch. Relations. By its anterior surface, with the Occipito-frontalis and Orbicularis palpebrarum muscles. By its posterior surface, with the frontal bone and supra- orbital vessels and nerve. The Levator Palpebral will be described with the muscles of the orbital region. The Tensor Tarsi is a small thin muscle, about three lines in breadth and six in leno*th, situated at the inner side of the orbit, beneath the Tendo oculi. R arises from the crest and adjacent part of the orbital surface of the lachrymal bone, and passing across the lachrymal sac, divides into two slips, which cover the la- chrymal canals, and are inserted into the tarsal cartilages near the Puncta lacrv- mal'ia. Its fibres appear to be continuous with those of the palpebral portion of the Orbicularis; it is occasionally very indistinct. Nerves. The Orbicularis palpebrarum and Corrugator supercilii are supplied by the facial and supraorbital nerves; the Tensor tarsi by the facial. Actions. The Orbicularis palpebrarum is the sphincter muscle of the eyelids. The palpebral portion acts involuntary in closing the lids, and independently of the orbicular portion, -which is subject to the will. When the entire muscle is brought into action, the integuments of the forehead, temple, and cheek are drawn inwards towards the inner angle of the eye, and the eyelids are firmly closed. The Levator palpebral is the direct antagonist of this muscle; it raises the upper eyelid, and exposes the globe. The Corrugator supercilii draws the eyebrow dowmvards and inwards, producing the verticle wrinkles of the forehead. This muscle may be regarded as the principal agent in the expression of grief. The Tensor tarsi draws the eyelids and the extremities of the lachrymal canals inAvards, and compresses them against the surface of the globe of the eye; thus placing them in the most favorable situation for receiving the tears. It serves, also, to compress the lachrymal sac. 1. Orbital Region (Fig. 13il). Levator Palpebrae Rectus Internus. Rectus Superior. Rectus Externus. Rectus Inferior. Obliquus Superior. Obliquus Inferior. Dissection. To open the cavity of the orbit, the skull-cap and brain should be first removed; then saw through the frontal bone at the inner extremity of the supraorbital ridge, and externally at its junction with the malar. The thin roof of the orbit should then bo comminuted by a few slight blows Avith the hammer, and the superciliary portion of the frontal bone driven forwards by a smart stroke; but must not be removed. The several fragments may then be detached, when the periosteum of the orbit will be exposed: this being removed, together with the fat which fills the cavity of the orbit, the several muscles of this region "can be examined. To facilitate their dissection, the globe of the eye should be distended; this may be effected by puncturing the optic nerve near the eyeball, with a curved needle, and pushing it onwards into the globe. Through this aper- ture the point of a blow-pipe should be inserted, and a little air forced into the cavity ot the eyeball; then apply a ligature around the nerve, so as to prevent the air escaping. The globe should now be drawn forwards, when the muscles will be put upon the stretch. The Levator Palpebral is a thin, flat, triangular muscle. It arises from the under surface of the lesser wing of the sphenoid, immediately above the optic foramen; and is inserted, by a broad aponeurosis, into the upper border of the superior tarsal cartilage. At its origin it is narrow and tendinous, but soon becomes broad and fleshy, and finally terminates in a broad aponeurosis. Relations. By its upper surface, with the frontal nerve and artery, the peri- osteum of the orbit; and in front with the inner surface of the broad tarsal liga- ORBITAL REGION. 193 ment. By its under surface, Avith the Superior rectus : and in the lid, Avith the' conjunctiva. The Rectus Superior (Attollens), the thinnest and narroAvest of the four recti, arises from the upper margin of the optic foramen, beneath the Levator palpebral and Superior oblique, and from the fibrous sheath of the optic nerve : and is Fig. 132.—Muscles of the Right Orbit. lent of the Muscles of the Left Eye- ball. JUrtus /Superior levator i FaLvcbra.S'uvtTurr inserted by a tendinous expansion, into the sclerotic coat of the eyeball, about three or four lines from the margin of the cornea. Relations. By its upper surface, Avith the Levator palpebral. By its under surface, Avith the optic nerve, the ophthalmic artery, and nasal nerve; and in front with.the tendon of the Superior oblique and the globe of the eye. The Inferior and Internal Recti arise by a common tendon (the ligament of Zinn), Avhich is attached around the circumferenc'e of the optic foramen, except at its upper and outer part. The External rectus has two heads; the upper Fig. 133.—The Relative PosWon and Attach- one arises from the outer margin of the optic foramen, immediately beneath the Su- perior rectus; the loAver head, partly from the ligament of Zinn, and partly from a small pointed process of bone on the loAver margin of the sphenoidal fissure. Each muscle passes forward in the position im- plied by its name, to be inserted, by a ten- dinous expansion, into the sclerotic coat of . f'f'f the eyeball, about three or four lines from the margin of the cornea. BetAveen the tAvo heads of the External rectus is a narroAv Rectus Infir interval, through which pass the third, nasal branch of the fifth and sixth nerves, and the ophthalmic vein. Although nearly all these muscles present a common origin, and are inserted in a similar manner into the sclerotic coat, there are certain differences to be observed in them, as re- gards their length and breadth. The Internal rectus is the broadest, the External the longest, and the Superior the thinnest and narrowest. The 'Superior Oblique is a fusiform muscle, placed at the upper and inner side of the orbit, internal to the Levator palpebrae. It rises about a line aboA-e the inner margin of the optic foramen, and, passing forAvards to the front and inner side of the orbit, terminates in a rounded tendon, which passes through a fibro- cartilaginous pulley attached to a depression beneath the internal angular process 15 />r Head 191 MUSCLES AND FASCRE. of the frontal bone, the contiguous surfaces of the tendon and pulley being lined by a delicate synovial membrane, and inclosed in a thin fibrous investment. The tendon is then reflected backAvards and outAvards beneath the Superior rectus to the outer and posterior part of the globe of the eye, and inserted into the sclerotic coat betAveen the Superior and External recti muscles, midway between the cornea and entrance of the optic nerve. Relations. By its upper surface, with the periosteum covering the roof of the orbit, and the fourth nerve. By its under surface, with the nasal nerve, and the upper border of the Internal rectus muscle. The Inferior Oblique is a thin, narroAv muscle, Avhich arises from a depression in the orbital plate of the superior maxillary bone, immediately external to the lachrymal groove. Passing outAvards and backAvards beneath the Inferior rectus, it terminates in a tendinous expansion, AAliich is inserted into the outer and pos- terior part of the sclerotic coat of the eyeball. Relations. By its superior surface, Avith the globe of the eye, and with the Infe- rior rectus. By its under surface, with the periosteum covering the floor of the orbit, and with the External rectus. Nerves. The Levator palpebrae, Inferior oblique, and all the recti excepting the External, are supplied by the third nerve: the Superior oblique by the fourth; the External rectus by the sixth. Actions. The Levator palpebrae raises the upper eyelid, and is the direct anta- gonist of the Orbicularis palpebrarum. The four Recti muscles are attached in such a manner to the globe of the eye, that, acting singly, they will turn it either upAvards, downwards, inAvards, or outAvards, as expressed by their names. If any two Recti act together, they carry the globe of the eye in the diagonal of these directions, viz., inwards and inwards, upAvards and outAvards, doAvnwards and inAvards, or doAvmvards and outwards. By some anatomists, these muscles have been considered the chief agents in adjusting the sight at different distances, by compressing the globe, and so lengthening its antero-posterior diameter. The Oblique are the " rotatory muscles" of the eyeball. The Superior oblique, acting alone, would rotate the globe, so as to carry the pupil outAvards and doAvnwards to the loAver and outer side of the orbit: the Inferior oblique rotating the globe in such a direction, as to carry the pupil upAvards and outwards to the upper and outer angle of the eye. Surgical Anatomy. The position and exact point of insertion of the tendons of the Internal and External recti muscles into the globe, should be carefully examined from the front of the eyeball, as the surgeon is often required to divide one or the other muscle for the cure of strabismus. In convergent strabismus, which is the most common furni of the disease, the eye is turned inwards, requiring the division of the Internal rectus. In the divergent form, which is more rare, the eye is turned outwards, the External rectus being especially implicated. The deformity produced in either case is considerable, and is easily remedied by division of one or the other muscle. This operation is readily effected by having the lids well separated by retractors held by an assistant, and the eye- ball being drawn outwards by a blunt hook ; the conjunctiva should be raised by a pair of forceps, and divided immediately beneath the lower border of the tendon of the Internal rectus, a little behind its insertion into the sclerotic : the submucous areolar tissue is then divided, and into the small aperture thus made, a blunt hook is passed upwards between the muscle and the plobe, and the tendon of the muscle and conjunctiva covering it, divided by a pair of blunt-pointed scissors. Or the tendon may be divided by a subconjunctival inci- sion, one blade of the scissors being passed upwards between the tendon and the conjunc- tiva, and the other betAveen the tendon and sclerotic. The student, when dissecting these muscles, should remove, on one side of the subject, the conjunctiva from the front of the eye, in order to see more accurately the position of these tendons, and on the opposite side the operation may be performed. NASAL REGION. 195 5. Nasal Region (Fig. 131). Pyramidalis Nasi. Levator Labii Superioris Alaeque Nasi. Levator Proprius Alae Nasi Posterior. Levator Proprius Ahc Nasi Anterior. Compressor Nasi. Compressor Narium Minor. Depressor Alae Nasi. The Pyramidalis Nasi is a small pyramidal slip of muscular fibre, prolonged dowmvards from the Occipito-frontalis upon the bridge of the nose, where it be- comes tendinous, and blends Avith the Compressor nasi. As the tAvo muscles descend, they diverge, leaving an angular interval between them, Avhich is filled up by cellular tissue. Relations. By its upper surface, with the skin. By its under surface, Avith the frontal and nasal bones. By its outer border, it is connected with the fleshy fibres of the Orbicularis palpebrarum. The Levator Labii Superioris Alosque Nasi is a thin, triangular muscle, situated alone the side of the nose, and extending between the inner margin of the orbit and upper lip. It arises by a, pointed extremity from the upper part of the nasal process of the superior maxillary bone, and passing obliquely downwards and out- wards, divides into two slips, one of Avhich is inserted into the cartilage of the ala of the nose; the other is prolonged into the upper lip, becoming blended Avith the Orbicularis and Levator labii proprius. Relations. In front, with the integument; and with a small part of the Orbicu- laris palpebrarum above. Lying upon the superior maxillary bone, beneath this muscle, is a longitudinal muscular fasciculus, about an inch in length. It is attached by one end near the origin of the Compressor naris, and by the other to the nasal process, about an inch above it; it Avas described by Albinus as the "* Musculus anomalus," and by Santorini, as the " Rhomboideus." The Levator Proprius Alee Nasi Posterior (Dilator naris posterior) is^a small muscle, which is placed partly beneath the proper elevator of the nose and lip. It arises from the margin of the nasal notch of the superior maxilla, and from the sesamoid cartilages, and is inserted into the skin near the margin of the nostril. The Levator Proprius Alas Nasi Anterior (Dilator naris anterior) is a thin, delicate fasciculus, passing from the cartilage of the ala of the nose to the integu- ment near its margin. This muscle is situated in front of the preceding. The Compressor Nasi is a small, thin, triangular muscle, arising by its apex from the superior maxillary bone, above and a little external to the incisive fossa; its fibres proceed upwards and inAvards, expanding into a thin aponeurosis which is attached to the fibro-cartilage of the nose, and is continuous on the bridge of the nose with that of the muscle of the opposite side, and with the aponeurosis of the pyramidalis nasi. The Compressor Narium Minor is a small muscle, attached by one end to the alar cartilage, and by the other to the integument at the end of the nose. The Depressor Abe Nasi (Myrtiformis) is a short, radiated muscle, arising from the incisive fossa of the superior maxilla; its fibres diverge upwards and outAvards; the upper, or ascending set, being inserted into the septum, and back part of the ala of the nose; the lower, or descending, into the back part of the upper segment of the orbicularis. Nerves. All the muscles of this group are supplied by the facial nerve. Actions. The Pyramidalis nasi draAvs down the inner angle of the eyebroAv; by some anatomists it is also considered as an elevator of the ala, and, consequently, a dilator of the nose. The Levator labii superioris alaeque nasi draAvs upAvards the upper lip and ala of the nose; its most important action is upon the nose, which it dilates to a considerable extent. The action of this muscle produces a marked 196 MUSCLES AND FASCRE. influence over the countenance, and is the principal agent in the expression of con- tempt. The two Levatores alae nasi are the dilators of the pinna of the nose and the Compressores nasi appear to act as dilators of the nose, rather than as con- strictors. The Depressor alae nasi is a direct antagonist of the preceding muscles draAving the upper lip and ala of the nose downAvards, and thereby constricting the aperture of the nares. G. Superior Maxillary Region (Fig. 181). Levator Labii Superioris Proprius. Zygomaticus Major. Levator Anguli Oris. Zygomaticus Minor. The Levator Labii Superioris Proprius is a thin muscle, of a quadrilateral form. It arises from the loAver margin of the orbit, immediately above the infraorbital foramen; some of its fibres being attached to the superior maxilla, some to the malar bone. Its fibres converge doAvmvards and inAvards, to be inserted into the muscular substance of the upper lip. Relations. By its superficial surface, with the loAver segment of the Orbicularis palpebrarum; beloAv, it is subcutaneous. By its deep surface, it "conceals the ori- gin of the Compressor nasi and Levator anguli oris muscles, and the infraorbital vessels and nerves, as they escape from the infraorbital foramen. The Levator Anguli Oris (musculus caninus) arises by a broad attachment from the canine fossa, immediately below the infraorbital foramen ; its fibres incline downAvards and a little outAvards, to be inserted into the angle of the mouth, inter- mingling its fibres Avith those of the Zygomatici, the Depressor anguli oris, and the Orbicularis. Relations. Its superficial surface is covered above by the Levator labii superioris proprius and the infraorbital vessels and nerves; beloAv, by the integument. By its deep surface, it is in relation with the superior maxilla, the Buccinator, and the mucous membrane. The Zygomaticus Major is a slender cylindrical fasciculus, which arises from the malar bone, in front of the zygomatic suture, and, descending obliquely downAvards and inAvards, is inserted into the angle of the mouth, Avhere it blends Avith the fibres of the Orbicularis and Depressor anguli oris. Relations. By its superficial surface, occasionally "with the Orbicularis palpebra- rum, above; and below, Avith the subcutaneous adipose tissue. By its deep surface, with the malar bone, the Masseter and Buccinator muscles. The Zygomaticus Minor arises from the malar bone, in front of the Zygomati- cus major, immediately behind the maxillary suture, and passing downAvards and inwards, is continuous with the outer margin of the Levator labii superioris pro- prius. Relations. By its superficial surface, with the integument and the Orbicularis palpebrarum above. By its deep surface, with the Levator anguli oris. Nerves. This group of muscles is supplied by the facial nerve. Actions. The Levator labii superioris proprius is the proper elevator of the upper lip, carrying it at the same time a little outAvards. The Levator anguli oris raises the angle of the mouth and draAvs it inAvards; Avhilst the Zygomatici raise the upper lip, and draAV it somewhat outAvards, as in laughing. 7. Inferior Maxillary Region (Fig. 131). Levator Labii Inferioris. Depressor Labii Inferioris (Quadratus menti). Depressor Anguli Oris (Triangularis menti). Dissection. The Muscles in this region may be dissected by making a vertical incision through the integument from the margin of the lower lip to the chin : a second incision should then be carried along the margin of the lower jaw as far as the angle, and the integu- ment carefully removed in the direction shown in Fig. 130. The Levator Labii Inferioris (Levator menti) is to be dissected by everting the MAXILLARY REGIONS. 197 lower lip and raising the mucous membrane. It is a small conical muscular fasci- culus, Avhich arises from the incisive fossa, external to the symphysis of the lower jaw; its fibres expand doAvnwards and forAvards, to be inserted into the integument of the chin. Jlelutions. On its inner surface, Avith the buccal mucous membrane; in the median line, it is blended with the muscle of the opposite side; and on its outer side, with the Depressor labii inferioris. The Depressor Labii Inferioris (Quadratus menti) is a small quadrilateral muscle, situated at the'outer side of the preceding. It arises from the external oblique line of the lower jaAv, betAveen the symphysis and mental foramen, and passes obliquely upwards and inAvards, to be inserted into the integument of the lower lip, its fibres blending Avith the Orbicularis, and with those of its fellow of the opposite side. It is continuous Avith the fibres of the Platysma at its origin. Relations. By its superficial surface, with part of the Depressor anguli oris, and with the integument, to Avhich it is closely connected. By its deep surface, with the mental vessels and nerves, the mucous membrane of the loAver lip, the labial glands and the Levator labii inferioris, with which it is intimately united. The Depressor Anguli Oris is a triangular muscle, arising, by its broad base, from the external oblique line of the lower jaAv; its fibres pass upAvards, to be inserted, by a thick and narrow fasciculus, into the angle of the mouth, being con- tinuous Avith the Orbicularis, Levator anguli oris, and Zygomaticus major. Relations. By its superficial surface, with the integument. By its deep sur- face, Avith the Depressor labii inferioris, the Platysma, and Buccinator. Nerves. This group of muscles is supplied by the facial nerve. Actions. The Levator labii inferioris raises the lower lip, and protrudes it for- wards ; at the same time it Avrinkles the integument of the chin. The Depressor labii inferioris draws the lower lip directly doAvnwards, and a little outAvards. The Depressor anguli oris depresses the angle of the mouth, being the great antagonist to the Levator anguli oris and Zygomaticus major: acting with those muscles, it will draw the angle of the mouth directly backwards. 8. Intermaxillary Region. Orbicularis Oris. Buccinator. Risorius. Dissection. The dissection of these muscles may be considerably facilitated by filling the cavity of the mouth with tow, so as to distend the cheeks and lips; the mouth should then be closed by a few stitches, and the integument carefully removed from the surface. The Orbicularis Oris is a sphincter muscle, elliptic in form, composed of con- centric fibres, which surround the orifice of the mouth. It consists of two thick semicircular planes of muscular fibre, which surround the oral aperture, and inter- lace on either side with those of the Buccinator and other muscles inserted into this part. On the free margin of the lips the muscular fibres are continued unin- terruptedly from one side to the other, forming a roundish fasciculus of fine pale fibres closely approximated. To the outer part of each segment some special fibres are added, by Avhich the lips are connected directly with the maxillary bones and septum of the nose. The additional fibres for the upper segment consist of four bands, tAvo of Avhich (Accessorii orbicularis superioris) arise from the alveo- lar border of the superior maxilla, opposite the incisor teeth, and arching out- wards on each side, are continuous at the angles of the mouth Avith the other muscles inserted into this part. The two remaining muscular slips, called the Naso-labialis, connect the upper lip to the septum of the nose: as they descend from the septum, an interval is left betiveen them, which corresponds to that left by the divergence of the accessory portions of the Orbicularis above described. It is this interval which forms the depression seen on the surface of the skin beneath the septum of the nose. lhose for the lower segment (Accessorii orbicularis inferioris) arise from the info- 198 MUSCLES AND FASCRE. rior maxilla, External to the Levator labii inferioris, near the root of the canine teeth, being separated from each other by a considerable interval ; arching out- Avards to the angles of the mouth, they join the Buccinator and the other muscles attached to this part. Relations. By its superficial surface, Avith the integument, to which it is closelv connected. By its deep surface, Avith the mucous membrane, the labial glands", and coronary vessels. By its outer circumference, it is blended with the nu- merous muscles, which converge to the mouth from various parts of the face. Its inner circumference is free, and covered by mucous membrane. The Buccinator is a broad, thin muscle, quadrilateral in form, occupying the interval betAveen the jaAvs at the side of the face. It arises, above, from the ex- ternal surface of the alveolar process of the upper jaAv, between the first molar tooth and the tuberosity: below, from the external surface of the alveolar process of the lower jaw, corresponding to the three last molar teeth ; and, behind, from the anterior border of the pterygo-maxillary ligament. The fibres of this muscle converge towards the angle of the mouth, where those occupying its centre inter- sect each other, the inferior fibres being continuous Avith the upper segment of the Orbicularis oris; the superior fibres, with the inferior segment; but the upper and lower fibres continue fonvard uninterruptedly into the corresponding segment of the lip. Relations. By its superficial surface, behind, with a large mass of fat, which separates it from the ramus of the lower jaAv, the Masseter, and a small portion of the Temporal muscle; anteriorly, with the Zygomatici, Risorius, Levator anguli oris, Depressor anguli oris, and Steno's duct, which pierces it opposite the second molar tooth of the upper jaw ; the transverse facial artery and vein lie parallel with its fibres, and the facial artery and vein cross it from below upwards; it in also crossed by the branches of the facial and buccal nerves. By its internal sur- face, with the buccal glands and mucous membrane of the mouth. The Pterygo-maxillary ligament separates the Buccinator muscle from the Superior constrictor of the pharynx. It is a tendinous band, attached by one extremity to the apex of the internal pterygoid plate, and by the other, to the posterior extremity of the internal oblique line of the lower jaw. Its inner sur- face corresponds to the cavity of the mouth, and is lined by mucous membrane. Its outer surface is separated from the ramus of the jaw by a quantity of adipose tissue. Its posterior border gives attachment to the Superior constrictor of the pharynx ; its anterior border, to the fibres of the Buccinator. The Risorius (Santorini) consists of a delicate bundle of muscular fibres, which arises in the fascia over the Masseter muscle, and passing horizontally forAvards. is inserted into the angle of the mouth, joining with the fibres of the Depressor anguli oris. It is placed superficial to the Platysma, and is broadest at its outer extremity. This muscle varies much in its size and form. Nerves. The Orbicularis oris is supplied by the facial, the Buccinator by the facial and buccal branch of the inferior maxillary nerve. Actions. The Orbicularis oris is the direct antagonist of all those muscles which converge to the lips from the various parts of the face, its action producing the direct closure of the lips ; and its forcible actions throwing the integment into Avrinkles, on account of the firm connection betAveen the latter and the surface of the muscle. The Buccinators contract and compress the cheeks, so that, during the process of mastication, the food is kept under the immediate pressure of the teeth. 0. Temporo-maxillary Region (Fig. 131). Masseter. Temporal. The Masseter muscle has been already exposed by the removal of the integu- ment from the side of the face (Fig. 131). The Masseter is a short thick muscle, someAvhat quadrilateral in form, consisting TEMPORO-MAXILLARY REGION. 199 of tAvo portions, superficial and deep. The superfic'odportion, the largest part of the muscle, arises by a thick tendinous aponeurosis from the malar process of the superior maxilla, and from the anterior two-thirds of the lower border of the zvgomatic arch : its fibres pass downAvards and backAvards, to be inserted into the lower half of the ramus and angle of the loAver jaAv. The deep portion is much smaller, more muscular in texture, and the direction of its fibres is forAvards; it arises from the posterior third of the loAver border and Avhole of the inner surface of the zygomatic arch, and is inserted into the upper half of the ramus and coro- noid process of the jaAv. The deep portion of the muscle is partly concealed, in front, by the superficial portion ; behind, it is covered by the parotid gland. The fibres of the tAvo portions are united at their insertion. Relations. By its superficial surface, Avith the integument; above, with the Orbicularis palpebrarum and Zygomaticus major; and has passing across it trans- versely, Steno's duct, the branches of the facial nerve, and the transverse facial artery. By its deep surface, Avith the ramus of the jaw, the Temporal muscle, and the Buccinator, from which it is separated by a mass of fat.. Its posterior margin is covered by the parotid gland. Its anterior margin is in relation, beloAV, with the facial artery. At this stage of the dissection, the temporal fascia is seen covering in the Tem- poral muscle. It is a strong aponeurotic investment, affording attachment, by its inner surface, to the superficial fibres of this muscle. Above, it is a single uniform layer, attached to the entire extent of the temporal ridge; but below, Avhere it is attached to the zygoma, it consists of two layers, one of Avhich is inserted into the outer, and the other to the inner border of the zygomatic arch. A small quantity of fat, and the orbital branch of the temporal artery, are contained between these. It is covered, on its outer surface, by the aponeurosis of the Occipito-frontalis, the Orbicularis palpebrarum, and Attollens and Attrahens aurem muscles; the temporal artery and vein, and ascending branches of the tem- poral nerves, cross it from it beloAV upAvards. Fig. 134.—The Temporal Muscle, the Zygoma and Masseter having been removed. Dissection. In order to expose the Temporal muscle, this fascia should be reinoATed; this may be eflFected by separating it at its attachment along the upper border of the zygoma, and dissecting it upwards from the surface of the muscle. The zygomatic arch should 200 MUSCLES AND FASCRE. then be divided in front at its junction with the malar bone, and, behind, near the external auditory meatus, and drawn downwards with the masseter, which should be detached froiu its insertion into the ramus and angle of the jaw. The whole extent of the Temporal muscle is then exposed. The Temporal is a broad radiating muscle, situated at the side of the head and occupying the entire extent of the temporal fossa. It arises from the whole of the temporal fossa, which extends from the external angular process of the frontal in front, to the mastoid portion of the temporal behind, and from the curved line on the frontal and parietal bones above, to the pterygoid ridge on the great wing of the sphenoid beloAV. It is also attached to the inner surface of the temporal fascia. Its fibres converge as they descend, the anterior passing obliquely back- Avards, the posterior obliquely forwards, and the middle fibres descend vertically, and terminate in an aponeurosis, the fibres of Avhich, radiated at its commence- ment, converge into a thick and flat tendon, Avhich is inserted into the inner surface, apex, and interior border of the coronoid process of the lower jaw. Relations. By its superficial surface, Avith the integument, the temporal fascia, aponeurosis of the Occipito-frontalis, the Attollens and Attrahens aurem muscles, the temporal vessels and nerves, the zygoma and Masseter. By its deep surface, with the temporal fossa, the External pterygoid and part of the Buccinator muscles, the internal maxillary artery, and its deep temporal branches. Nerves. Both muscles are supplied by the inferior maxillary nerve. 10. Pterygo-maxillary Regiox. Internal Pterygoid. External Pterygoid. Dissection. The temporal muscle having been examined, the muscles in the pterygo-maxil- lary region may be exposed by sawing through the base of the coronoid process, and drawing it upwards, together with the Temporal muscle, which should be detached from the surface of the temporal fossa. Divide the ramus of the jaw just below the condyle, and also, by a transverse incision extending across the commencement of its lower third, just above the dental foramen; remove the fragment, and the Pterygoid muscles will be exposed. Fig. 135—The Pterygoid Muscles, the Zygomatic Arch and a portion of the Ramus of the Jaw having been removed. The Internal Pterygoid is a thick quadrilateral muscle, and resembles the Masseter in form, structure, and in the direction of its fibres. It arises from the PTERYGO-MAXILLARY REGION. 201 pterygoid fossa, its fibres being attached to the inner surface of the external ptery- goid plate of the sphenoid, and to the grooved surface of the tuberosity of the palate bone; its fibres descend downAvards, outwards, and backAvards, to be inserted, by strong tendinous lamina?, into the lower and back part of the inner side of the ramus and angle of the loAver jaAv. Relations. Py its external surface, with the ramus of the loAver jaAv, from which it is separated at its upper part by the External pterygoid, the internal lateral ligament, the internal maxillary artery, and the superior dental vessels and nerves. By its internal surface, with the Tensor palati, being separated from the Superior constrictor of the pharynx by a cellular interval. The External Pterygoid is a short thick muscle, somewhat conical in form, being broader at its origin than at its insertion. The two extremities of the muscle are tendinous, the intervening portion being fleshy. It arises by two heads, separated by a cellular interval. The upper head is attached to the ptery- goid ridge on the great ala of the sphenoid, and the portion of bone included be- tween it and the base of the external pterygoid plate ; the other, the larger fasci- culus, from the outer surface of the external pterygoid plate, and part of the tuberosity of the palate bone. From this origin, its fibres proceed horizontally backwards and outwards, to be inserted into a depression on the anterior part of the neck of the condyle of the loAver jaAv, and into the corresponding part of the interarticular fibro-cartilage. Relations. By its external surface, with the ramus of the loAver jaw, the inter- nal maxillary artery, which crosses it, the tendon of the Temporal muscle, and the Masseter. By its internal surface, it rests against the upper part of the Internal pterygoid, the internal lateral ligament, the middle meningeal artery, and inferior maxillary nerve: by its upper border it is in relation Avith the temporal and masseteric branches of the inferior maxillary nerve. Nerves. These miuscles are supplied by the inferior maxillary nerve. Actions. The Temporal, Masseter, and Internal pterygoid raise the loAver jaw against the upper Avith great force. The tAvo latter muscles, from the obliquity in the direction of their fibres, assist the External pterygoid in draAving the lower jaw forAvards upon the upper, the jaAV being drawn back again by the deep fibres of the Masseter, and posterior fibres of the Temporal. The external pte- rygoid muscles are the direct agents in the trituration of the food, draAving the lower jaAv directly forAvards, so as to make the loAver teeth project beyond the upper. If the muscle of one side acts, the corresponding side of the jaAv is drawn forwards, and the other condyle remaining fixed, the symphysis deviates to the opposite side. The alternation of these movements on the tAvo sides produces trituration. MUSCLES AND FASCIAE OF THE NECK. The Muscles of the Neck may be arranged into groups, corresponding with the region in Avhich they are situated. These groups are nine in number. 1. Superficial Region. 6. Muscles of the Soft Palate. 2. Depressors of the Os Ilyoides 7. Muscles of the Anterior Ver- and Larynx. tebral Region. 3. Elevators of the Os Ilyoides 8. Muscles of the Lateral Ver- and Larynx. tebral Region. 1. Muscles of the Tongue. n -\r i p ,i t y. Muscles of the Larynx. 5. Muscles of the Pharynx. 202 MUSCLES AND FASCRE. 1. Superficial Region. Platysma myoides. Sterno-cleido-mastoideus. Infra-hyoid Region. 2. Depressors of the Os Hyoides and Larynx. Sterno-hyoid. Sterno-thyroid. Thyro-hyoid. Omo-hyoid. Supra-hyoid Region. 3. Elevators of the Os Hyoides and Larynx. Digastric. Stylo-hyoid. Mylo-hyoid. Genio-hyoid. Lingual Region. 4. Muscles of the Tongue. Genio-hyo-glossus. Hyo-glossus. Lingualis. Stylo-glossus. Palato-glossus. 5. Muscles of the Pharynx. Constrictor inferior. Constrictor medius. Constrictor superior. Stylo-pharyngeus. Palato-pharyngeus. 6. Muscles of the Soft Palate. Levator Palati. Tensor palati. Azygos muilae. Palato-glossus. Palato-pharyngeus. 7. Muscles of the Anterior Vertebral Region. Rectus capitis anticus major. Rectus capitis anticus minor. Rectus lateralis. Longus colli. 8. Muscles of the Lateral Vertebral Region. Scalenus anticus. Scalenus medius. Scalenus posticus. 9. Muscles of the Larynx. Included in the description of the Larynx. 1. Superficial Region (Fig. 131). Platysma Myoides. Sterno-cleido-mastoid. Dissection. A block having been placed at the back of the neck, and the face turned to the side opposite to that to be dissected, so as to place the parts upon the stretch, two transverse incisions are to be made; one from the chin, along the margin of the lower jaw, to the mastoid process; and the other along the upper border of the clavicle. These are to be connected by an oblique incision made in the course of the Sterno-mastoid muscle, from the mastoid process to the sternum; the two flaps of integument having been removed in the direction shown in Fig. 130, the superficial fascia will be exposed. The Superficial Cervical Fascia is exposed on the removal of the integument from the side of the neck; it is an extremely thin aponeurotic lamina, which is hardly demonstrable as a separate membrane. Beneath it is found the Platysma myoides muscle, the external jugular vein, and some superficial branches of the cervical plexus of nerves. The Platysma Myoides is a broad thin flat plane of muscular fibres, of an irregular quadrilateral form, placed immediately beneath the skin on each side ot the neck. It arises from the clavicle and acromion, and from the fascia covering the upper part of the Pectoral, Deltoid, and Trapezius muscles ; its fibres proceed obliquely upAvards and inwards along the side of the neck, to be inserted into the lower jaw beneath the external oblique line, some fibres passing forAvards to the angle of the mouth, and others becoming lost in the cellular tissue of the face. The most anterior fibres interlace, in front of the jaAv, Avith the fibres of the muscle of the opposite side; those next in order become blended Avith the Depres- sor labii inferioris and the Depressor anguli oris ; others are prolonged upon the side of the cheek, and interlace, near the angle of the mouthy Avith the muscles in this situation, and may occasionally be traced to the Zygomatic muscles, or to the SUPERFICIAL CERVICAL REGION. 203 margin of the Orbicularis palpebrarum. The most posterior fibres, Avhich are lost in the skin at the side of the face, are the rudiments of a remarkable acces- sory fasciculus, the Risorius Santorini, already described. Beneath this muscle, the external jugular vein may be seen descending from the angle of the jaAv to the clavicle. It is essential to remember the direction of the fibres of the Pla- tysma, in connection Avith the operation of bleeding from this vessel; for if the point of the lancet is introduced in the direction of the fibres of this muscle, the orifice made Avill be filled up by its contraction, and blood will not Aoav ; but if the incision is made in a direction opposite to that of the course of the fibres, they will retract, and expose the orifice in the vein, and so facilitate the flow of blood. This operation is, now, hoAvever, very rarely performed. Relations. By its externed surface, Avith the integument, to which it is united closely beloAv, but more loosely above. By its internal surface, below the clavicle, which it covers, Avith the Pectoralis major, Deltoid, and Trapezius. In the neck, with the external and anterior jugular veins, the deep cervical fascia, the super- ficial cervical plexus, the Sterno-mastoid, Sterno-hyoid, Omo-hyoid, and Digastric muscles. In front of the Sterno-mastoid, it covers the sheath of the carotid ves- sels ; and behind it, the Scaleni muscles and the nerves of the brachial plexus. On the/«cc, it is in relation Avith the parotid gland, the facial artery and vein, and the Masseter and Buccinator muscles. The Deep Cervical Fascia is exposed on the removal of the platysma myoides. It is a strong fibrous layer, which invests the muscles of the neck, and incloses the vessels and nerves. It commences, as an extremely thin layer, at the back part of the neck, Avhere it is attached to the spinous processes of the cervical vertebra?, and to the ligamentum nuchae ; and, passing forwards to the posterior border of the Sterno-mastoid muscle, divides into two layers, one of Avhich passes in front, and the other behind it. These join again at its anterior border ; and, being continued forAvards to the front of the neck, blend Avith the fascia of the opposite side. The superficial layer of the deep cervical fascia (that which passes in front of the Sterno-mastoid), if traced upwards, is found to pass across the parotid gland and Masseter muscle, forming the parotid and masseteric fasciae, and is attached to the loAver border of the zygoma, and more anteriorly to the lower border of the body of the jaAv; if the same layer is traced downwards, it is seen to pass to the upper border of the clavicle and sternum, being pierced just above the former bone for the external jugular vein. In the middle line of the neck, this layer is thin above, and connected to the hyoid bone ; but it becomes thicker beloAv, and divides, just beloAv the thyroid gland, into tAvo layers, the more superficial of Avhich is attached to the upper border of the sternum and inter- clavicular ligament; the deeper and stronger layer is connected to the posterior border of that bone, covering in the Sterno-hyoid and Sterno-thyroid muscles. BetAveen these two layers is a little areolar tissue and fat, and occasionally a small lymphatic gland. The deep layer of the cervical fascia (that Avhich lies behind the posterior surface of the Sterno-mastoid) sends numerous prolongations, which invests the muscles and vessels of the neck ; if traced upAvards, a process of this fascia, of extreme density, passes behind rfnd to the inner side of the parotid gland, and is attached to the base of the styloid process and angle of the lower jaw, forming the stylo-maxillary ligament; if traced downAvards and outwards, it will be found to inclose the posterior belly of the Omo-hyoid muscle, binding it down by a distinct process, Avhich descends to be inserted into the clavicle and cartilage of the first rib. The deep layer of the cervical fascia also assists in forming the sheath which incloses the common carotid artery, internal jugular vein, and pneumogastric nerve. There are fibrous septa intervening betAveen each of these parts, Avhich, however, are included together in one common investment. More internally, a thin layer is continued across the trachea and thyroid gland, beneath the Sterno-thyroid muscles; and at the root of the neck this may be traced, over the large vessels, to be continuous Avith the fibrous layer of the peri- cardium. 204 MUSCLES AND FASCRE. The Sterno-cleido-mastoid (Fig. 136) is a large, thick muscle, which passes obliquely across the side of the neck, being inclosed betAveen the tAvo layers of the deep cervical fascia. It is thick and narrow at its central part, but is broader and thinner at each extremity. It arises, by tAvo distinct heads, from the sternum and clavicle. The sternal portion arises by a rounded fasciculus, tendinous in front, fleshy behind, from the upper and anterior part of the first piece of the sternum, and is directed upAvards and backAvards. The clavicular portion arises from the inner third of the upper surface of the clavicle, being composed of fleshy and aponeurotic fibres; it is directed perpendicularly upwards. These two por- tions are separated from one another, at their origin, by a triangular cellular interval; but become gradually blended, below the middle of the neck, into a thick rounded muscle, which is inserted, by a strong aponeurosis, into the outer surface of the mastoid process, from the apex to its superior border, and into the Fig. 136.—Muscles of the Neck, and Boundaries of the Triangles. outer two-thirds of the superior curved line of the occipital bone. This muscle varies much in its extent of attachment to the clavicle ; in one case it may be as narrow as the sternal portion; in another, as much as three inches in breadth. When the clavicular origin is broad, it is occasionally subdivided into numerous slips, separated by narroAv intervals. More rarely the corresponding margins of the Sterno-mastoid and Trapezius have been found in contact. In the application of a ligature to the third part of the subclavian artery, it Avill be necessary, Avhere the muscles have an arrangement similar to that above mentioned, to divide a por- tion of one or of both, in order to facilitate the operation. This muscle serves to divide the large quadrilateral space at the side of the neck into two large triangles, an anterior and a posterior. The boundaries of the great anterior triangle being, in front, the median line of the neck ; above, the INFRAHYOID REGION. 205 lower border of the body of the jaw, and an imaginary line drawn from the ano-le of the jaAV to the mastoid process; behind, the anterior border of the Sterno-mastoid muscle. The boundaries of the great posterior triangle are, in front, the poste- rior border of the Sterno-mastoid; below, the upper border of the clavicle; behind, the anterior margin of the Trapezius. The anterior edge of this muscle forms a very prominent ridge beneath the skin, which forms a guide to the surgeon in making the incisions for ligature of the common carotid artery, and for oesophagotomy. Relations. By its superficial surface, Avith the integument and Platysma, from which it is separated by the external jugular vein, the superficial branches of the cervical plexus, and the anterior layer of the deep cervical fascia. By its deep surface, it rests on the deep layer of the cervical fascia, the sterno-clavicular articulation, the Sterno-hyoid, Sterno-thyroid, and Omo-hyoid muscles, the poste- rior belly of the Digastric, Levator anguli scapulas, the Splenius and Scaleni muscles. BeloAV, with the loAver part of the common carotid artery, internal jugular vein, pneiimogastric, descendens noni, and communicans noni nerves, and with the deep lymphatic glands ; with the spinal accessory nerve, Avhich pierces its upper third, the cervical plexus, the sympathetic nerve, and the parotid gland. Nerves. The Platysma myoides is supplied by the facial and superficial cer- vical nerves; the Sterno-cleido-mastoid by the spinal accessory and deep branches of the cervical plexus. Actions. The Platysma myoides produces a slight Avrinkling of the surface of the skin of the neck, in a vertical direction, Avhen the entire muscle is brought into action. Its anterior portion, the thickest part of the muscle, depresses the lower jaw; it also serves to draw doAvn the lower lip and angle of the mouth on each side, being one of the chief agents in the expression of melancholy. The accessory transverse fibres draw the angle of the lips upwards and outAvards, as in laughing. The Sterno-mastoid muscles, when both are brought into action, serve to depress the head upon the neck, and the neck upon the chest. Either muscle, acting singly, flexes the head, and (combined with the Splenius) draAvs it toAvards the shoulder of the same side, and rotates it so as to carry the face tOAvards the opposite side. Infrahyoid Region (Figs. 136, 137). 2. Depressors of the Os Hyoides and Larynx. Sterno-hyoid. Thyro-hyoid Sterno-thyroid, Omo-hyoid. Dissection. The muscles in this region may be exposed by removing the deep fascia from the front of the neck. In order to see the entire extent of the Omo-hyoid, it is necessary to divide the Sterno-mastoid at its centre, and turn its ends aside, and to detach the Trapezius from the clavicle and scapula, if this muscle has been previously dissected; but not otherwise. The Sterno-hyoid is a thin, narrow, ribbon-like muscle, which arises from the inner extremity of the clavicle, and the upper and posterior part of the first piece of the sternum ; and, passing upAvards and inAvards, is inserted, by short tendinous fibres, into the loAver border of the body of the os hyoides. This muscle is separated, beloAv, from its fellow by a considerable interval; they approach one another in the middle of their course, and again diverge as they ascend. It often presents, immediately above its origin, a transverse tendinous intersection, analogous to those in the Rectus abdominis. J ariations in Origin. The origin of this muscle presents many variations. Thus, it may be found to arise from the inner extremity of the clavicle, and the posterior sterno-claAucular ligament; or from the sternum and this ligament; from either bone alone, or from all these parts ; and occasionally has a fasciculus connected with the cartilage of the first rib. 200 MUSCLES AND FASCIiE. Relations. By its superficial surface, below, with the sternum, sternal end of the clavicle, and the Sterno-mastoid ; and, above, Avith the Platysma and deep cervical fascia. By its deep surface, with the Sterno-thyroid, Crico-thyroid, and Thyro-hyoid muscles, the thyroid gland, the superior thyroid artery, the crico- thyroid and thyro-hyoid membranes. The Sterno-thyroid is situated immediately beneath the preceding muscle, but is shorter and broader than it. It arises from the posterior surface of the first bone of the sternum, beneath the origin of the Sterno-hyoid, and occasionally from the edge of the cartilage of the first rib; and is inserted into the oblique line on the side of the ala of the thyroid cartilage. These muscles are in close contact Fig. 137.—Muscles of the Neck. Anterior View. at the lower part of the neck by their inner margins; and are frequently traversed by transverse or oblique tendinous intersections, analogous to those in the Rectus abdominis. Variations. This muscle, at its insertion, is liable to some variations. A lateral prolongation is sometimes continued as far as the os hyoides ; and it is sometimes continuous with the Thyro-hyoideus and Inferior constrictor of the pharynx. Relations. By its anterior surface, with the Sterno-hyoid, Omo-hyoid, and Sterno-mastoid. By its posterior surface, from below upwards, with the trachea, vena innominata, common carotid (and on the right side the arteria innominata), the thyroid gland and its vessels, and the lower part of the larynx. The middle thyroid vein lies along its inner border; this should be remembered in the operation of tracheotomy. The Thyro-hyoid is a small quadrilateral muscle, appearing like a continuation of the Sterno-thyroid. It arises from the oblique line on the side of the thyroid cartilage, and passes vertically upwards to be inserted into the lower border of the body, and greater cornu of the hyoid bone. SUPRAHYOID REGION. 207 Relations. By its external surface, with the Sterno-hyoid and Omo-hyoid muscles. By its internal surface Avith the thyroid cartilage, and thyro-hyoid membrane. Interposed betAveen this muscle and the membrane, is the superior laryngeal nerve and artery. The Omo-hyoid passes across the side of the neck, from the scapula to the hyoid bone. It consists of tAVo fleshy bellies, united by a central tendon. It arises from the upper border of the scapula, and occasionally from the transverse ligament which crosses the suprascapular notch; its extent of attachment to the scapula varying from a few lines to an inch. From this origin, the posterior belly forms a flat, narrow fasciculus, Avhich inclines fonvards across the lower part of theneck; behind the Sterno-mastoid muscle, where it becomes tendinous, it changes its direction, forming an obtuse angle, and ascends almost vertically upwards, close to the outer border of the Sterno-hyoid, to be inserted into the lower border of the body of the os hyoides, just external to the insertion of the Sterno-hyoid. The tendon of this muscle, which varies much in its length and form in different subjects, is held in its position between tAvo lamellae of the deep cervical fascia, Avhich include it in a sheath, and are prolonged doAvn to be attached to the cartilage of the first rib. It is by this means that the angular form of the muscle is maintained. This muscle subdivides each of the two large triangles at the side of the neck, formed by the Sterno-mastoid, into two smaller triangles ; the two posterior ones being the posterior superior or suboccipital, and the posterior inferior or sub- clavian ; the tAvo anterior, the anterior superior or superior carotid, and the ante- rior inferior or inferior carotid triangle. Relations. By its superficial surface, with the Trapezius, Subclavius, the clavicle, the Sterno-mastoid, deep cervical fascia, Platysma, and integument. By its deep surface, Avith the Scaleni, brachial plexus, sheath of the common carotid artery, and internal jugular Arein, the descendens noni nerve, Sterno-thyroid and Thyro-hyoid muscles. Nerves. All the muscles of this group, excepting the Thyro-hyoid, which is supplied by the hypoglossal, receive their nerves from the loop of communication between the descendens and communicans noni. Actions. These muscles serve to depress the larynx and hyoid bone, after these parts have been drawn up Avith the pharynx in the act of deglutition. The Omo- hyoid muscles not only depress the hyoid bone, but carry it backAvards, and to one or the other side. The muscles are also tensors of the cervical fascia. The Thyro-hyoid may act as an elevator of the thyroid cartilage, when the hyoid bone ascends, draAving upwards the thyroid cartilage behind the os hyoides. Suprahyoid Region (Figs. 136, 137). 3. Elevators of the Os Hyoides—Depressors of the Loaver Jaw. Digastricus. Mylo-hyoid. Stylo-hyoid. Genio-hyoid. Dissection. To dissect these muscles, a block should be placed beneath the back of the neck, and the head drawn backwards, and retained in that position. On the removal of the deep fascia, the muscles are at once exposed. The Digastric, so called from its consisting of two fleshy bellies united by an intermediate rounded tendon, is a small muscle, situated immediately beneath the side of the body of the loAver jaw, and extending in a curved form,, from the side of the head to the symphysis of the jaw. The posterior belly, longer than the 4 anterior, arises from the digastric groove on the inner side of the mastoid process of the temporal bone, and passes doAvmvards, forAvards, and inAvards. The ante- rior belly, being reflected upwards and forAvards, is inserted into a depression on the inner side of the lower border of the jaAV, close to the symphysis. The 208 MUSCLES AND FASCIA. tendon of this muscle perforates the Stylo-hyoid, and is held in connection with the side of the body of the hyoid bone by an aponeurotic loop, lined by a synovial membrane. A broad aponeurotic layer is given off from the tendon of the digastric on each side, which is attached to the hyoid bone : this is termed the suprahyoid aponeurosis. It forms a strong layer of fascia betAveen the anterior portion of the two muscles, and forms a firm investment for the other muscles of the suprahyoid region, Avhich lie beneath it. The Digastric muscle divides the anterior superior triangle of the neck into tAvo smaller triangles; the upper, or submaxillary, being bounded above by the loAver jaw; beloAV, by the tAvo bellies of the Digastric muscle: the lower, or supe- rior carotid triangle, being bounded above by the posterior belly of the Digastric • behind, by the Sterno-mastoid; below, by the Omo-hyoid (Fig. 136). Relations. By its superficial surface, with the Platysma, Sterno-mastoid, part of the Stylo-hyoid muscle, and the parotid and submaxillary glands. By its deep surface, its anterior belly lies on the Mylo-hyoid, the posterior belly lies on the Stylo-glossus, Stylo-pharyngeus, and Hyo-glossus muscles, the external carotid and its lingual and facial branches, the internal carotid, internal jugular vein and hypoglossal nerve. The Stylo-hyoid is a small, slender muscle, lying in front of, and above the posterior belly of the Digastric. It arises from the middle of the outer surface of the styloid process; and, passing dowmvards and forwards, is inserted into the body of the hyoid bone, just at its junction Avith the greater cornu, and imme- diately above the Omo-hyoid. This muscle is perforated near its insertion by the tendon of the Digastric muscle. Relations. By its superficial surface, with the Sterno-mastoid and Digastric muscles, the parotid and submaxillary glands. Its deep surface has the same re- lations as the posterior belly of the Digastric. Dissection. The Digastric and Stylo-hyoid muscles should be removed, in order to expose the next muscle. The Mylo-hyoid is a flat triangular plane of muscular fibre, situated imme- diately beneath the anterior belly of the Digastric, and forming, with its fellow of the opposite side, a muscular floor for the cavity of the mouth. It arises from the whole length of the mylo-hyoid ridge, from the symphysis in front, to the last molar tooth behind. The posterior fibres pass obliquely forwards, to be inserted into the body of the os hyoides. The middle and anterior fibres are inserted into the median fibrous raphe, where they join at an angle with the fibres of the oppo- site muscle. This median raphe is sometimes wanting ; the muscular fibres of the tAvo sides are then directly continuous with one another. Relations. By its superficial or inferior surface with the Platysma, the ante- rior belly of the Digastric, the suprahyoid fascia, the submaxillary gland, and submental vessels. By its deep or superior surface, with the Genio-hyoid, part of the Hyo-glossus, and Stylo-glossus muscles, the lingual and gustatory nerves, the sublingual gland, and the buccal mucous membrane. Wharton's duct curves around its posterior border in its passage to the mouth. Dissection. The Mylo-hyoid should now be removed, in order to expose the muscles which he beneath; this is effected by detaching it from its attachments to the hyoid bone and jaw, and separating it by a vertical incision from its fellow of the opposite side. The Genio-hyoid is a narrow slender muscle, situated immediately beneath the inner border of the preceding. It arises from the inferior genial tubercle on the inner side of the symphysis of the lower jaAv, and descends downwards and back- wards, to be inserted into the anterior surface of the body of the os hyoides. This muscle lies in close contact with its fellow of the opposite side, and increases slightly in breadth as it descends. Relations. It lies between the Mylo-hyoid and the Genio-hyo-glossus muscles. LINGUAL REGION. 200- Nerves. The Digastric is supplied, its anterior belly, by the mylo-hyoid branch of the inferior dental; its posterior belly, by the facial and glosso-pharyngeal; the Stylo-hyoid, by the facial and glosso-pharyngeal; the Mylo-hyoid, by the mylo- hyoid branch of the inferior dental; the Genio-hyoid, by the lingual. Actions. This group of muscles performs two very important actions. They raise the hyoid bone, and Avith it the base of the tongue, during the act of degluti- tion ; or, Avhen the hyoid bone is fixed by its depressors, and those of the larynx, they depress the lower jaw. During the first act of deglutition, Avhen the mass is being driven from the mouth into the pharynx, the hyoid bone, and with it the tongue, is carried upwards and forAvards by the anterior belly of the Digastric, the Mylo-hyoid, and Genio-hyoid muscles. In the second act, when the mass is pass- ing, the direct elevation of the hyoid bone takes place by the combined action of all the muscles; and, after the food has passed, the hyoid bone is carried upAvards and backwards by the posterior belly of the Digastric and Stylo-hyoid muscles, which assists in preventing the return of the morsel into the cavity of the mouth. 1. Lingual Region. Genio-hyo-glossus. Lingualis. Hyo-glossus. Stylo-glossus. Palato-glossus. Dissection. After completing the dissection of the preceding muscles, saw through the lower jaw, just external to the symphysis. The tongue should then be drawn forwards with a hook, and its muscles, which are thus put on the stretch, may be examined. Fig. 138.—Muscles of the Tongue. Left Side. The Genio-hyo-glossus has received its name from its triple attachment to the chin, hyoid bone, and tongue : it is a thin, flat, triangular muscle, placed vertically in the middle line, its apex corresponding with its point of attachment to the loAver jaw, its base with its insertion into the tongue and hyoid bone. It arises by a 210 MUSCLES AND FASCRE. short tendon from the superior genial tubercle on the inner side of the symphysis of the chin, immediately above the Genio-hyoid ; from this point the muscle spreads out in a fan-like form, the inferior fibres passing downwards, to be inserted into the upper part of the body of the hyoid bone, a few being continued into the side of the pharynx ; the middle fibres passing backAvards, and the anterior ones up- Avards and forwards, to be attached to the whole length of the under surface of the tongue, from the base to the apex. Relations. By its internal surface, it is in contact Avith its felloAv of the opposite side, from Avhich it is separated, at the back part of the tongue, by a fibro-cellular structure, Avhich extends forAvards through the middle of the organ. Bv its ex- ternal surface, Avith the Lingualis, Hyo-glossus, and Stylo-glossus. the lingual artery and hypoglossal nerve, the gustatory nerve, and the sublingual gland. By its upper border, with the mucous membrane of the floor of the mouth. By its lower border, Avith the Genio-hyoid. The Hyo-glossus is a thin, flat, quadrilateral plane of muscular fibres, arising from the body, the lesser cornu, and whole length of the greater cornu of the hyoid bone, and, passing almost vertically upAvards, is inserted into the side of the tongue, betAveen the Stylo-glossus and Lingualis. Those fibres of this muscle Avhich arise from the body are directed upwards and backAvards, overlapping those from the greater cornu, which are directed obliquely forAvards. Those from the lesser cornu extend forAvards and outAvards along the side of the tongue, under cover of ihe portion arising from the body. The difference in the direction of the fibres of this muscle, and their separate origin from different segments of the hyoid bone, led Albinus and other anato- mists to describe it as three muscles, under the names of the Basio-glossus,' the Cerato-glossus, and the Chondro-glossus. Relations. By its external surface, with the Digastric, the Stylo-hyoid, Stylo- glossus, and Mylo-hyoid muscles, the gustatory and hypoglossal nerves', Wharton's duct, and the sublingual gland. By its deep surface, Avith the Genio-hyo-glossus, Lingualis, and the origin of the Middle constrictor muscle of the pharynx, the lingual artery, and the glosso-pharyngeal nerve. The Lingualis is a longitudinal band of muscular fibres, situated on the under surface of the tongue, lying in the interval between the Hyo-glossus and the Genio-hyo-glossus, and extending from the base to the apex of that organ. Pos- teriorly, some of its fibres are lost in the base of the tongue, and others arc attached to the hyoid bone. It blends with the fibres of the Stylo-glossus, in front of the Hyo-glossus, and is continued forAvards as far as the apex of the tongue. It is in relation, by its under surface, Avith the ranine artery. The Stylo-glossus, the shortest and smallest of the three styloid muscles, arises from the anterior and outer side of the styloid process, near its centre, and from the stylo-maxillary ligament, to which its fibres in most cases are attached by a thin aponeurosis. Passing downwards and forwards, so as to become nearly horizontal in its direction, it divides upon the side of the tongue into two portions; one lon- gitudinal, which is inserted along the side of the tongue, blending with the fibres of the Lingualis, in front of the Hyo-glossus ; the other oblique, which overlaps the Hyo-glossus muscle, and decussates with its fibres. Relations. By its external surface, from above downwards, with the parotid gland, the Internal pterygoid muscle, the sublingual gland, the gustatory nerve, and the mucous membrane of the mouth. By its internal surface, with the tonsil, the Superior constrictor muscle of the pharynx, and the Hvo-glossus muscle. The Palato-glossus, or Constrictor Isthm'i Faucium, although one of the muscles of the tongue, serving to draw its base upwards during the act of deglutition, is more nearly associated with the soft palate, both in its situation and function ; it will, consequently, be described with that group of muscles. Nerves. The muscles of the tongue are supplied by the hypoglossal nerve, excepting the Palato-glossus, which receives its nerves from the palatine branches if Meckel's ganglion. PHARYNGEAL REGION. 211 Actions. The movements of the tongue, although numerous and complicated, may easily be explained by carefully considering the direction of the fibres of the muscles of this organ. The Genio-hyo-glossi, by means of their posterior and inferior fibres, draw upwards the hyoid bone, bringing it and the base of the tongue forwards, so as to protrude the apex from the mouth. The anterior fibres will restore it to its original position by retracting the organ within the mouth. The whole length of these two muscles acting along the middle line of the tongue will draw it downwards, so as to make it concave from before backwards, forming a channel along which fluids may pass towards the pharynx, as in sucking. The Ilyo-glossi muscles draw down the sides of the tongue, so as to render it convex from side to side. The Linguales, by drawing downwards the centre and apex of the tongue, render it convex from before backwards. The Palato-glossi draw the base of the tongue upwards, and the Stylo-glossi upwards and backAvards. 5. Pharyngeal Region. Constrictor Inferior. Constrictor Superior. Constrictor Medius. Stylo-pharyngeus. Palato-pharyngeus. Dissection (Fig. 139). In order to examine the muscles of the pharynx, cut through the trachea and oesophagus just above the sternum, and draw them upwauls by dividing the loose areolar tissue connecting the pha- rynx with the front of the verte- Fig. 139— Muscles of the Pharynx. External View. bral column. The parts being drawn well forwards, the edge of the saw should be applied immedi- ately behind the styloid processes, and the base of the skull sawn through from below upwards. The pharynx and mouth should v then be stuffed with tow, in order x to distend its cavity and render the muscles tense and easier of dissection. The Inferior Constrictor, the most superficial and thickest of the three, arises from the side of the cricoid and thyroid car- tilages. To the cricoid carti- lage it is attached in the inter- val between the crico-thyroid, in front, and the articular facet for the thyroid cartilage behind. To the thyroid cartilage, it is attached to the oblique line on the side of the great ala, the cartilaginous surface behind it, nearly as far as its posterior border, and to the inferior cornu. From these attach- ments, the fibres spread backAvards and inAvards, to be inserted into the fibrous raphe in the posterior median line of the pharynx. The inferior fibres are hori- zontal, and overlap the commencnieut of the (esophagus ; the rest ascend, increas- ing in obliquity, aud overlap the Middle constrictor. The superior laryngeal nerve passes near the upper border, and the inferior, or recurrent laryngeal, benealh the loAver border of this muscle, previous to their entering the larynx. Rifations. It is covered by a dense cellular membrane which surounds the o]o MUSCLES AND FASCRE. entire pharynx. Behind, it lies on the vertebral column and the Longus colli. Laterally, it is in relation Avith the thyroid gland, the common carotid artery, and the Sterno-thyroid muscle. By its internal surface, Avith the Middle constrictor, the Stylo-pharyngeus, Palato-pharyngeus, and the mucous membrane of the pharynx. The Middle Constrictor is a flattened, fan-shaped muscle, smaller than the pre- ceding, and situated on a plane anterior to it. It arises from the whole length of the upper border of the greater cornu of the hyoid bone, from the apex of this cornu by a tendinous origin, from the lesser cornu, and from the stylo-hyoidean ligament. The fibres diverge from their origin in various directions; the lower ones descending and being overlapped by the Inferior constrictor, the middle fibres passing transversely, and the upper fibres ascending to cover in the Superior con- strictor. It is inserted into the posterior median fibrous raphe, blending in the middle line Avith the fibres of the opposite muscle. Relations. This muscle is separated from the Superior constrictor by the glosso- pharyngeal nerve and the Stylo-pharyngeus muscle; and from the Inferior constric- tor by the superior laryngeal nerve. Behind, it lies on the vertebral column, the Longus colli, and the Pectus anticus major. On each side it is in relation with the carotid vessels, the pharyngeal plexus, and some lymphatic glands. Near its origin, it is covered by the hyo-glossus, from Avhich it is separated by the lingual artery. It covers in the Superior constrictor, the Stylo-pharyngeus, the Palato- pharyngeus, and the mucous membrane. The Superior Constrictor is a quadrilateral plane of muscular fibres, thinner and paler than those of the other Constrictors, situated at the upper part of the pha- rynx. It arises from the lower third of the margin of the internal pterygoid plate and its hamular process, from the contiguous portion of the palate bone and the reflected tendon of the Tensor palati muscles, from the pterygo-maxillary ligament, from the alveolar process above the posterior extremity of the mylo-hyoid ridge, and by a few fibres from the side of the tongue in connection with the Genio-hyo- glossus. From these points, the fibres curve backAvards, to be inserted into the median raphe, being also prolonged by means of a fibrous aponeurosis to the pha- ryngeal spine on the basilar process of the occipital bone. Its superior fibres arch beneath the Levator palati and the Eustachian tube, the interval betAveen this bor- der of the muscle and the basilar process being deficient in muscular fibres, and closed by fibrous membrane. Relations. By its outer surface, behind, with the vertebral column. On each Hide, Avith the carotid vessels, the internal jugular vein, the three divisions of the eighth and the ninth nerves, the Middle constrictor which overlaps it, and the Stylo-pharyngeus. Internally, it covers the Palato-pharyngeus and the tonsil, and is lined by mucous membrane. The Stylo-pharyngeus is a long, slender muscle, round above, broad and thin beloAv. It arises from the inner side of the base of the styloid process, passes downwards and inAvards to the side of the pharynx betAveen the Superior and Middle constrictors, and spreading out beneath the mucous membrane, some of its fibres are lost in the Constrictor muscles, and others joining Avith the Palato-pha- ryngeus, are inserted into the posterior border of the thyroid cartilage. The glosso-pharyngeal nerve runs on the outer side of this muscle, and crosses over it in passing forward to the tongue. Relations. Externally, with the Stylo-glossus muscle, the external carotid artery, the parotid gland, and the Middle constrictor. Internally, with the internal caro- tid, the internal jugular vein, the Superior constrictor, Palato-pharyngeus, and mucous membrane. Nerves. The muscles of this group are supplied by branches from the pharyngeal plexus and glosso-pharyngeal nerve ; and the Inferior constrictor, by an additional branch from the external laryngeal nerve. Actions. When deglutition is about to be performed, the pharynx is drawn upwards and dilated in different directions, to receive the morsel propelled into it PALATAL R KG ION. 213 from the mouth. The Stylo-pharyngei, which are much farther removed from one another at their origin than at their insertion, draAv upwards and outAvards the sides of this cavity, the breadth of the pharynx in the anterior-posterior direction being increased, by the larynx and tongue being carried forAvards in their ascent. As soon as the morsel is received in the pharynx, the elevator muscles relax, the bag descends, and the Constrictors contract upon the morsel, and convey it gradually doAvnAvards into the (esophagus. The pharynx also exerts an important influence in the modulation of the voice, especially in the production of the higher tones. 6. Palatal Region. Levator Palati. Azygos Uvulae. Tensor Palati. Palato-glossus. Palato-pharyngeus. Dissection (Fig 110). Lay open the pharynx from behind, by a vertical incision extending from its upper to its lower part, and the posterior surface of the soft palate is exposed Having fixed the uvula so as to make it tense, the mucous membrane and trlands should be carefully removed from the posterior surface of the soft palate and the muscles of this part are at once exposed. Fig. 140.—Muscles of the Soft Palate. The Pharynx being laid open from behind. The Levator Palati is a long, thin muscle, placed on the outer side of the pos- terior aperture of each nasal fossa. It arises from the apex of the basilar surface of the petrous portion of the temporal bone and from the adjoining cartilaginous portion of the Eustachian tube: after passing into the interior of the pharynx, aboA-e the upper concave margin of the Superior constrictor, it descends obliquely dowmvards and inAvards, its fibres spreading out in the posterior surface of the 211 MUSCLES AND FASCRE. soft palate as far as the middle line, where they blend Avith those of the opposite side. Relations. Externally, with the Tensor palati and Superior constrictor. Inter- nally, it is lined by the mucous membrane of the pharynx. Posteriorly, with the mucous lining of the soft palate. This muscle must be removed and the pterygoid attachment of the Superior constrictor dissected away, in order to expose the next muscle. The Circumflexus or Tensor Palati is a broad, thin, flat muscle, placed on the outer side of the preceding, and consisting of two distinct portions, a vertical and horizontal. The vertical portion arises by a broad, thin, and flat lamella from the scaphoid fossa at the base of the internal pterygoid plate, its fibres of origin extending as far back as the spine of the sphenoid ; it also arises from the anterior aspect of the cartilaginous portion of the Eustachian tube, descending vertically doAvnAvards betAveen the internal pterygoid plate and the inner surface of the Internal pterygoid muscle ; it terminates in a tendon which Avinds around the hamular process, being retained in this situation by a tendon of origin of the Internal pterygoid muscle, and lubricated by a synovial membrane. The tendon or horizontal portion then passes horizontally inAvards, and expands into a broad aponeurosis on the anterior surface of the soft palate, which unites in the median line Avith the aponeurosis of the opposite muscle, the fibres of Avhich are attached anteriorly to the transverse ridge on the posterior border of the horizontal portion of the palate bone. Relations. Externally, with the Internal pterygoid. Internally, with the Levator palati, from Avhich it is separated by the Superior constrictor, and the in- ternal pterygoid plate. In the soft palate its aponeurotic expansion is anterior to that of the Levator palati, being covered by mucous membrane. The Azygos Uvulce is not a single muscle as implied by its name, but a pair of small cylindrical fleshy fasciculi, placed side by side in the median line of the soft palate. Each muscle arises from the posterior nasal spine of the palate bone, and from the contiguous tendinous aponeurosis of the soft palate, and descending vertically doAvnwards, is inserted into the uvula. Relations. Anteriorly, with the tendinous expansion of the Levatores palati; behind, with the mucous membrane. The two next muscles are exposed by removing the mucous membrane which covers the pillars of the soft palate on each side throughout their whole extent. The Palato-glossus or Constrictor Isthmi Faucium, is a small fleshy fasci- culus, narrower in the middle than at either extremity, forming, with the mucous membrane covering its surface, the anterior pillar of the soft palate. It arises from the soft palate on each side of the uvula, and passing forwards and outwards in front of the tonsil, is inserted into the side and upper surface of the tongue, where it blends with the fibres of the Stylo-glossus muscle. In the soft palate^t-he fibres' of origin of this muscle are continuous with those of the opposite side, and with the Palato-pharyngeus. The Palato-pharyngeus is a long fleshy fasciculus, narrower in the middle than at either extremity, forming, with the mucous membrane covering its surface, the posterior pillar of the soft palate. It is separated from the preceding by an angular interval, in which the tonsil is lodged. It arises from the soft palate by an expanded fasciculus, its fibres being divided into two unequal parts by the Levator palati, and being continuous partly Avith the muscle of the opposite side, and partly with the fibrous aponeurosis of the palate. Passing outwards and down- wards behind the tonsil, it joins the Stylo-pharyngeus, and is inserted with it into the posterior border of the thyroid cartilage, some of its fibres being lost on the side of the pharynx. Relations. In the soft palate, its anterior and posterior surfaces are covered by mucous membrane, from which it is separated by a layer of palatine glands. By its superior border, it is in relation with the Levator palati. Where it forms the posterior pillar of the fauces, it is covered by mucous membrane, excepting on its ANTERIOR VERTEBRAL REGION. 215 outer surface. In the pharynx, it lies betAveen the mucous membrane and the constrictor muscles. Nerves. The Tensor palati is supplied by a branch from the otic ganglion; the other muscles by the palatine branches of Meckel's ganglion. Actions. When the morsel of food has been driven backwards into the fauces by the pressure of the tongue against the hard palate, the Palato-glossi muscles, the constrictors of the fauces, contract behind it, the soft palate is slightly raised by the Levator palati, and made tense by the Tensor palati, and the Palato-pha- ryngei contract, and come nearly together, the Uvula filling up the slight interval betAveen them. By these means, the food is prevented passing into the upper part of the pharynx, or the posterior nares : at the same time theTatter muscles form an inclined plane, directed obliquely doAvnwards and backwards, along which the morsel descends into the pharynx. Surgical Anatomy. The muscles of the soft palate should be carefully dissected, the rela- tions they bear to the surrounding parts especially examined, and their action attentively studied upon the dead subject, as the surgeon is required to divide one or more of these muscles m the operation of staphylorraphy. Mr. Fergusson has shown that in the congeni- tal deficiency called cleft patatr, the edges of the fissure are forcibly separated by the action of the Levatores palati and Palato-pharyngei muscles, producing very considerable, impedi- ment to the healing process after the performance of the operation for uniting their margins by adhesion : he has, consequently, recommended the division of these muscles as one of the most important steps in the operation : by these m-ans, the flaps are relaxed, lie perfectly loose ami pendulous, and are easily brought and retained in apposition. The Palato-pha- ryngei may be divided by cutting across the posterior pillar of the soft palate, just below the tonsil, with a pair of blunt-pointed curved scissors, and the anterior pillar may be divided also. To divide the Levator palati, the plan recommended by Mr. Pollock is to be greatly preferred. The flap being put upon the stretch, a double-edged knife is passed through the soft palate just on the inner side of the bamular process, and abo\-e the line of the Levator palati. The handle being now alternately raised and depressed, a sweeping cut is made along the posterior surface of the soft palate, aud the knife withdrawn, leaving but a small opening in the mucous membrane on the anterior surface. If this operation is performed on the dead body, and the parts afterwards dissected, the Levator palati will be found com- pletely divided. 7. Vertebral Region (Anterior). Rectus Capitis Anticus Major. Rectus Lateralis. Rectus Capitis Anticus Minor. Longus Colli. The Rectus Capitis Anticus Major (Fig. 141), broad and thick aboAre, narrow below, appears like a continuation upAvards of the Scalenus anticus. It arises by four tendons from the anterior tubercles of the transverse processes of the third, fourth, fifth, and sixth cervical vertebra?, and ascends, converging towards its fel- low of the opposite side, to be inserted into the basilar process of the occipital bone. Relations. By its anterior surface, Avith the pharynx, the sympathetic nerve, and the sheath inclosing the carotid artery, internal jugular vein, and pneumogastric nerve. By its posterior surface, with the Longus colli, the Rectus anticus minor, and the upper cervical vertebrae. The Rectus Capitis Anticus Minor is a short muscle, situated immediately be- neath the upper part of the preceding. It arises from the anterior surface of the lateral mass of the atlas, and from the root of its transverse process ; passing obliquely upAvards and inwards, it is inserted into the basilar process immediately behind the preceding muscle. .Relations. By its anterior surface, with the Rectus anticus major. By its pos- terior surface, with the anterior part of the occipito-atlantal articulation. Exter- nally, with the superior cervical ganglion of the sympathetic. The Rectus Lateralis is a short, flat muscle, situated betAveen the transverse process of the atlas and the jugular process of the occipital bone. It arises from 21U MUSCLES ANI) FASCRE. the upper surface of the transverse process of the atlas, and is inserted into the under surface of the jugular process of the occipital bone. Rilations. By its anterior surface, with the internal jugular vein. By its -pos- terior surface, with the vertebral artery. The Longus Cdli is a long, flat muscle, situated on the anterior surface of the spine, between the atlas and the third dorsal vertebra, being broad in the middle, narrow and pointed at each extremity. It consists of three portions, a superior oblique, an inferior oblique, and a vertical portion. The superior oblique portion arises by a narrow tendon from the tubercle on the anterior arch of the atlas, and, descending obliquely outAvards. is inserted into the anterior tubercles of the transverse processes of the third, fourth, and fifth cervical vertebra?. The inferior oblique portion, the smallest part of the muscle, arises tendinous Fig. ill.—The Prevertebral Muscles. from the transverse processes of the fifth and sixth cervical vertebra, and, passing obliquely inwards, is inserted into the bodies of the first two or three dorsal vertebra. The vertical portion lies directly on the front of the spine, and is extended be- tween the bodies of the second, third, and fourth cervical vertebras above, and the bodies of the three lower cervical and the three upper dorsal below. Relations. By its anterior surface, with the pharynx, the oesophagus, sympa- thetic nerve, the sheath of the carotid artery, internal jugular vein, and pneiimo- gastric nerve, inferior thyroid artery, and recurrent 'laryngeal nerve. P»v its posterior surface, with the cervical and dorsal portions of the spine. LATERAL VERTEBRAL REGION. 217 8. Vertebral Region (Lateral). Scalenus Anticus. Scalenus Medius. Scalenus Posticus. The Scalenus Anticus is a triangular muscle, situated deeply at the side of the neck, behind the Sterno-mastoid. It arises by a narrow, flat tendon from the tubercle on the inner border and upper surface of the first rib, and ascending ver- tically upAvards, is inserted into the anterior tubercles of the transverse processes of the third, fourth, fifth, and sixth cervical vertebras. The lower part of this muscle separates the subclavian artery and vein; the latter being in front, and the former, with the brachial plexus, behind. Relations. By its anterior surface, with the Sterno-mastoid and Omo-hyoid muscles, the transversalis Colli, and descending cervical arteries, and the phrenic nerve. By its posterior surface, with the subclavian artery, and brachial plexus of nerves. It is separated from the Longus colli on the inner side by the subcla- vian artery. The Scalenus Medius, the largest and longest of the three Scaleni, arises, by a broad origin, from the upper surface of the first rib, behind the groove for the subclavian artery, as far back as the tubercle, and ascending along the side of the vertebral column, is inserted, by separate tendinous slips, into the posterior tubercles of the transverse processes of the six loAver cervical vertebras. It is separated from the Scalenus anticus by the subclavian artery below, and the cervical nerves above. Relations. By its external surface, with the Sterno-mastoid; it is crossed by the clavicle and Omo-hyoid muscle. To its outer side, is the Le\rator anguli scapulae and the Scalenus posticus muscle. The Scalenus Posticus, the smallest of the three Scaleni, arises by a thin tendon from the outer surface of the second rib, behind the attachment of the Serratus magnus, and enlarging as it ascends, is inserted, by two or three separate tendons, into the posterior tubercles of the transverse processes of the tAvo or three lower cervical vertebrse. This is the most deeply placed of three Scaleni, and is occa- sionally blended with the Scalenus medius. Nerves. The Rectus capitis anticus major and minor are supplied by the subocci- pital and deep branches of the cervical plexus; the Rectus lateralis by the subocci- pital; and the Longus colli and Scaleni by branches from the loAver cervical nerves. Actions. The Rectus anticus major and minor are the direct antagonists of those placed at the back of the neck, serving to restore the head to its natural position, when drawn backAvards by the posterior muscles. These muscles also serve to boAv the head forAvards. The Longus colli will flex and slightly rotate the cervical portion of the spine. The Scaleni muscles, taking their fixed point from beloAv, draw down the transverse processes of the cervical vertebrae, flexing the spinal column to one or the other side. If the muscles of both sides act, the spine will be kept erect. When taking their fixed point from above, they elevate the first and second ribs, and are, therefore, inspiratory. MUSCLES AND FASCIA OF THE TRUNK. The muscles of the trunk may be subdivided into four groups. 1. Muscles of the Back. 3. Muscles of the Thorax. 2. Muscles of the Abdomen. 4. Muscles of the Perinasum. Muscles of the Back. The Muscles of the Back are very numerous, and may be subdivided into five layers. First Layer. Second Layer. Trapezius. Levator anguli scapuhv. Latissimus dorsi. Rhomboideus minor. Rhomboideus major. 218 MUSCLES AND FASCRE. Third Layer. Serratus posticus superior. Serratus posticus inferior. Splenius capitis. Splenius colli. Fourth Layer. Sacral and Lumbar Regions. Erector Spinas. Dorsal Region. Sacro-lumbalis. Musculus accessorius ad sacro-lumbalem. Longissimus dorsi. Spinalis dorsi. Cervical Region. Cervicalis ascendens. Transversalis cervicis. Trachclo-mastoid. Complexus. Biventer cervicis. Spinalis cervicis. Fifth Layer. Semispinalis dorsi. Semispinalis colli. Multifidus spinae. Rotatores spinas. Supraspinales. Interspinales. Extensor coccygis. Inter transversales. Rectus posticus major. Rectus posticus minor. Obliquus superior. Obliquus inferior. First Layer. Trapezius. Latissimus Dorsi. Dissection (Fig. 112). The body should be placed in the prone position, with the arms extended over the sides of the table, and the chest and abdomen supported by several blocks so as to render the muscles tense. An Fig. 14*2.—Dissection of the Muscles of the Back, incision should then be made along the middle line of the back, from the occipital protube- rance to the coccyx. From the upper end of this, a transverse incision should extend to the mastoid process; and from the lower end a third incision should be made along the crest of the ilium to about its middle. This large inter- vening space, for convenience of dissection, should be subdivided by a fourth incision, ex- tending obliquely from the spinous process of the last dorsal vertebra, upwards and outwards, to the acromion process. This incision corre- sponds with the lower border of the Trapezius muscle. The flaps of the integument should then be removed in the direction shoAvn in the accompanying figure. The Trapezius is a broad, flat, trian- gular muscle, placed immediately beneath the skin, and covering the upper and back part of the neck and shoulders. It arises from the occipital protuberance and inner third of the superior curved line of the occipital bone; from the ligamentum nuchas, the spinous processes of the seventh cervical, and all the dorsal ver- tebras, and from the corresponding por- tion of the supraspinous ligament. From these points the muscular fibres proceed, the superior ones downAvards and out- Avards, the inferior ones upAvards and n 1 . outAvards, and the middle fibres horizon- tally, and are inserted, the superior ones curving forwards into the outer third of the posterior border of the clavicle, the middle fibres into the upper margin of the acromion process, and into the whole length of the upper border of the spine of the scapula; the inferior fibres converge near the scapula, and are attached OF THE BACK. 219 Fig. 143.—Muscles of the Back. On the Left Side is exposed the First Layer; on the Right Side, the Second Layer and part of the Third. 220 MUSCLES AND FASCRE. to a triangular aponeurosis, which glides over a small triangular surface at the inner extremity of the spine, and is inserted into a small tubercle in immediate connection with its outer part. The Trapezius is fleshy in the greater part of its extent, but tendinous at its origin and insertion. At its occipital orio-in it is connected to the bone by a thin fibrous lamina, firmly adherent to the skin and wanting the lustrous, shining appearance of aponeurosis. At its origin from the spines of the vertebra\ it is connected by means of a broad semi-elliptical aponeu- rosis, which occupies the space betAveen the sixth cervical and the third dorsal vertebrae, and forms, Avith the muscle of the opposite side, a tendinous ellipse. The remaining part of the origin is effected by numerous short tendinous fibres. If the Trapezius is dissected on both sides, the two muscles resemble a trapezium or diamond-shaped quadrangle; tAvo angles, corresponding to the shoulders ; a third, to the occipital protuberance; and the fourth, to the spinous process of the last dorsal vertebra. The clavicular insertion of this muscle varies as to the extent of its attachment; it sometimes advances as far as the middle of the clavicle, and may even become blended Avith the posterior edge of the Sterno-mastoid, or overlap its margin. This should be borne in mind in the operation for tying the subclavian artery. Relations. By its superficial surface, with the integument to which it is closelv adherent above, but separated beloAv by an aponeurotic lamina. By its deep sur- face, in ^ the neck, with the Complexus, Splenius, Levator anguli scapulas, and Rhomboideus minor; in the back, with the Rhomboideus major, Supraspinatus, Infraspinatus, a small portion of the Serratus posticus superior, the intervertebral aponeurosis which separates it from the Erector spinas, and with the Latissimus dorsi. The spinal accessory nerve passes beneath the anterior border of this muscle, near the clavicle. The outer margin of its cervical portion forms the posterior boundary of the large posterior triangle of the neck, the other boundaries being the Sterno-mastoid in front, and the clavicle below. The Ligamentum Nuchee (Fig. 143) is a thin band of condensed cellulo-fibrous membrane, placed in the line of union betAveen the two Trapezii in the neck. It extends from the external occipital protuberance to the spinous process of the seventh cervical vertebra, where it is continuous with the supraspinous ligament. From its anterior surface, a fibrous slip is given off to the spinous processes of each of the cervical vertebras, excepting the atlas, so as to form a septum between the muscles on each side of the neck. In the human subject it is merely the rudi- ment of an important elastic ligament, which serves to sustain the weight of the head in some of the lowTer animals. The Latissimus Dorsi is a broad flat muscle, which covers the lumbar and lower half of the dorsal regions, and is gradually contracted into a narrow fasci- culus at its insertion into the humerus. It arises by tendinous fibres from the spinous processes of the six inferior dorsal, from those of the lumbar and sacral vertebras, and from the supraspinous ligament. Over the sacrum, the aponeurosis of this muscle blends with the tendon of the Erector spinas. It also arises from the external lip of the crest of the ilium, behind the origin of the external oblique, and by fleshy digitations from the three or four lower ribs, being interposed be- tAveen similar processes of the External oblique muscle. From this extensive origin the fibres pass in different directions, the upper ones horizontally, the middle ones obliquely upwards, and the lower ones vertically upwards, so as to converge and form a thick fasciculus, which crosses the inferior angle of the scapula, and occasionally receives a few fibres from it. The muscle then curves around the lower border of the Teres major, and is twisted upon itself, so that the superior fibres become at first posterior and then inferior, and the vertical fibres at first anterior and then superior. It then terminates in a short quadri- lateral tendon, about three inches in length, which, passing in front of the tendon of the leres major, is inserted into the bottom of the bicipital groove of the humerus, above the insertion of the tendon of the Pectoralis major. The loAver border of the tendon of this muscle is united with that of the Teres major, the surfaces of OF THE BACK. 221 the two being separated by a synovial bursa; a second synovial bursa is interposed betAveen the muscle and the inferior angle of the scapula. The origin of this muscle from the spine and ilium is effected by an aponeu- rosis, which assists in forming the sheath for the Erector spinas. Its costal attachment takes place by means of three or four fleshy slips, Avhich interdigitate with the External oblique muscle of the abdomen. Relations. Its superficial surface is subcutaneous, excepting at its upper part, where it is covered by the Trapezius. By its deep surface, it is in relation "with the Erector spinas, the Serratus posticus inferior, Intercostal muscles and ribs, the Serratus magnus, inferior angle of the scapula, Rhomboideus major, Infraspinatus, and Teres major. Its external margin is separated beloAv, from the external oblique, by a small triangular interval; and another triangular interval exists betAveen its superior border and the margin of the Trapezius, in Avhich the Inter- costal and Rhomboideus major muscles are exposed. N'rves. The Trapezius is supplied by the spinal accessory and cervical plexus; the Latissimus dorsi, by the subscapular nerves. Second Layer. Levator Anguli Scapulas. Rhomboideus Minor. Rhomboideus Major. Distortirm. The Trapezius must be removed in order to expose the next layer ; to effect this, the muscle must be detached from its attachment to the clavicle and spine of the sca- pula, and turned back towards the spine. The Levator Anguli Scapula is a long, thick, and someAvhat flattened muscle, situated at the posterior part and side of the neck. It arises by four tendons from the posterior tubercles of the transverse processes of the three or four upper cer- vical vertebras ; these becoming fleshy are united so as to form a flat muscle, which, passing doAvmvards and backwards, is inserted into the posterior border of the scapula, betAveen the superior angle and the triangular smooth surface at the root of the spine. Relations. By its superficial surface, with the integument, Trapezius, and Sterno- mastoid. By its deep surface, with the Splenius colli, Transversalis colli, Cervi- calis ascendens, and Serratus posticus superior, and Avith the transverse cervical and posterior scapular arteries. The Rhomboideus Minor arises from the ligamentum.nucha, and spinous pro- cesses of the seventh cervical and first dorsal vertebra', its fibres of origin being intimately united with those of the Trapezius. Passing downwards and outAvards, it is inserted into the margin of the triangular smooth surface at the root of the spine of the scapula. This small muscle is usually separated from the Rhom- boideus major by a slight cellular interval. The Rhomboideus Major is situated immediately below the preceding, the adja- cent margins of the tAvo being occasionally united. It arises by tendinous fibres from the spinous processes of the four or five upper dorsal vertebras and their interspinous ligaments, and is inserted into the posterior border of the scapula, between the triangular surface at the base of the spine and the inferior angle. The insertion of this muscle takes place by means of a narrow, tendinous arch, attached above, to the triangular surface near the spine; below, to the inferior angle, the arch being connected to the border of the scapula by a thin membrane. When the arch extends, as it occasionally does, but a short distance, the muscular fibres are inserted into the scapula itself. Relations. By their superficial surface, with the integument, and Trapezius, the Rhomboideus major, with' the Latissimus dorsi. By their deep surface with the Serratus posticus superior, posterior scapular artery, part of the Erector spinas, the Intercostal muscles and ribs. Nerves. These muscles are supplied by branches from the fifth cervical nerve, and additional filaments from the deep branches of the cervical plexus are distri- buted to the Levator anguli scapulas. 222 MUSCLES AND FASCIA. Actions. The movements effected by the preceding muscles are numerous, as may be conceived from their extensive attachment. If the head is fixed, the upper part of the Trapezius will elevate the point of the shoulder, as in supporting weights; Avhen the middle and loAver fibres are brought into action, partial rotation of the scapula upon the side of the chest is produced. If the shoulders are fixed, both Trapezii acting together will draw the head directly backwards, or if only one acts, the head is drawn to the corresponding side. The Latissimus Dorsi, Avhen it acts upon the humerus, draAvs it backAvards and doAvmvards, and at the same time rotates it inAvards. If the arm is fixed, the muscle may act in various Avays upon the trunk; thus, it may raise the loAver ribs and assist in forcible inspiration, or if both arms are fixed, the tAvo muscles may conspire Avith the abdominal and great Pectoral muscles in drawing the Avhole trunk forAvards, as in climbing, or Avalking on crutches. The Levator Anguli Scapula' raises the superior angle of the scapula after it has been depressed by the Trapezius, whilst the Rhomboid muscles carry the infe- rior angle backAvards and upAvards, thus producing a slight rotation of the scapula upon the side of the chest. If the shoulder be fixed, the Levator scapulas may incline the neck to the corresponding side. The Rhomboid muscles, acting together with the middle and inferior fibres of the Trapezius, will draw the scapula directly backAvards towards the spine. Third Layer. Serratus Posticus Superior. Serratus Posticus Inferior. 0 , . f Splenius Capitis. Splenius. | g£len.us Cof1L Dissection. The third layer of muscles is brought into view by the entire removal of the preceding, together with the Latissimus dorsi. To effect this, the Levator anguli scapula; and Rhomboid muscles should be detached near their insertion, and reflected upwards, thus exposing the Serratus posticus superior; the Latissimus dorsi should then be divided in the middle by a vertical incision carried from its upper to its lower part, and the two halves of the muscle reflected. The Serratus Posticus Superior is a thin, flat muscle, irregularly quadrilateral in form, and situated at the upper and back part of the thorax. It arises by a thin and broad aponeurosis, from the ligamentum nuchae and from the spinous pro- cesses of the last cervical and two or three upper dorsal vertebrse. Inclining doAvnAvards and outAvards, it becomes muscular, and is inserted by four fleshy dic- tations, into the upper borders of the second, third, fourth, and fifth ribs, a little beyond their angles. Relations. By its superficial surface, Avith the Trapezius, Rhomboidei, and Ser- ratus magnus. By its deep surface, with the Splenius, upper part of the Erector spinae, Intercostal muscles and ribs. The Serratus Posticus Inferior is situated at the lower part of the dorsal and upper part of the lumbar regions: it is of an irregularly quadrilateral form, broader than the preceding, and separated from it by a considerable interval. It arises by a thin aponeurosis from the spinous processes of the tAvo lower dorsal and tAvo or three upper lumbar vertebrae, and from the interspinous ligaments. Passing obliquely upwards and outwards, it becomes fleshy, and divides into four flat digitations, which are inserted into the lower borders of the four lower ribs, a little beyond their angles. Relations. By its superficial surface, it is covered by the Latissimus dorsi, with the aponeurosis of which its own aponeurotic origin is inseparably blended. By its deep surface, with the posterior aponeurosis of the Transversalis, the Erector spinas, ribs and Intercostal muscles. Its upper margin is continuous with the ver- tebral aponeurosis. The Vertebral Aponeurosis is a thin aponeurotic lamina, extending along the Avhole length of the posterior part of the thoracic region, serving to bind down the Erector spinse, and separating it from those vessels which connect the spine to OF THE BACK. 223 the upper extremity. It consists of longitudinal and transverse fibres blended together, forming a thin lamella, which is attached in the median line to the spi- nous processes of the dorsal vertebrae ; externally, to the angles of the ribs ; and beloAV, to the upper border of the Serratus posticus inferior and tendon of the Latis- simus dorsi; above, it passes beneath the Serratus posticus superior, and blends Avith the deep fascia of the neck. The Serratus posticus superior should now be detached from its origin and turned out- wards, when the Splenius muscle will be brought into view. The Sjdenius is a broad muscle, situated at the posterior part of the neck and upper part of the dorsal region. At its origin, it is a single muscle, narroAv and pointed in form ; but it soon becomes broader, and divides into tAvo portions, which have separate insertions. It arises, by tendinous fibres, from the lower half of the Ligamentum nuchas, from the spinous processes of the last cervical and of the six upper dorsal vertebra, and from the supraspinous ligament. From this origin, the fleshy fibres proceed obliquely upwards and outAvards, forming a broad flat muscle, which divides as it ascends into tAvo portions, the Splenius capitis and Splenius colli. The Splenius capitis is inserted into the mastoid process of the temporal bone, and into the rough surface on the occipital bone beneath the superior curved line. The Sjdenius colli is inserted, by tendinous fasciculi, into the posterior tubercles of the transverse processes of the three or four upper cervical vertebra. The Splenius is separated from its fellow of the opposite side by a triangular interval, in which is seen the Complexus. Relations. By its superficial surface, with the Trapezius, from which it is sepa- rated beloAV by the Rhomboidei and the Serratus posticus superior. It is also covered by the Sterno-mastoid and Levator anguli scapula. By its deep surface, with the Spinalis dorsi, Longissimus dorsi, Semispinalis colli, Complexus, Trachelo- mastoid, and Transversalis colli. Nerves. The Splenius and Superior serratus are supplied from the external posterior branches of the cervical nerves; the Inferior serratus, from the external branches of the dorsal nerves. Actions. The Serrati are respiratory muscles acting in antagonism to each other. The Serratus posticus superior eleArates the ribs ; it is, therefore, an inspi- ratory muscle; while the Serratus posticus inferior draAvs the lower ribs dowmvards, and is a muscle of expiration. This muscle is also probably a tensor of the verte- bral aponeurosis. The Splenii muscles of the tAvo sides, acting together, draw the head directly backAvards, assisting the Trapezius and Complexus ; acting sepa- rately, they draAv the head to one or the other side, and slightly rotate it, turning the face to the same side. They also assist in supporting the head in the erect position. Fourth Layer. Sacral and Lumbar Regions. Cervical Region. Erector Spina. Cervicalis ascendens. Dorsal Region. Transversalis cervicis. Sacro-lumbalis. Trachelo-mastoid. Musculus accessorius ad sacro-lumbalem. Complexus. Longissimus dorsi. Biventer cervicis. Spinalis dorsi. Spinalis cervicis. Dissection. To expose the muscles of the fourth layer, the Serrati and vertebral aponeu- rosis should be entirely removed. The Splenius may then be detached by separating its attachments to the spinous processes, and reflecting it outwards. The Erector Spina (Fig. Ill), and its prolongations in the dorsal and cervical regions, fill up the vertebral groove on each side of the spine. They are covered in the lumbar region by the lumbar aponeurosis : in the dorsal region, by the Serrati muscles and the vertebral aponeurosis : and in the cervical region, by a 221 MUSCLES AND FASCRE. Fig. 144.—Muscles of the Back. Deep Layers. ,ctJ> ilal l0 MULTITIDUS SPIN/S 1*tRU V.'.Luuibeir V OF THE BACK. 225 layer of cervical fascia continued beneath the Trapezius. This large muscular and tendinous mass varies in size and structure at different parts of the spine. In the sacral region, the Erector spina is narroAv and pointed, and its origin chiefly ten- dinous in structure. In the lumbar region, it becomes enlarged, and forms a large fleshy mass. In the dorsal region, it subdivides into tAvo parts, Avhich gradually diminish in size as they ascend to be inserted into the vertebra and ribs, and are gradually lost in the cervical region, where a number of special muscles are super- added, Avhich are continued upAvards to the head, Avhich they support upon the spine. The Erector spina arises from the sacro-iliac groove, and from the anterior sur- face of a very broad and thick tendon, Avhich is attached, internally, to the spines of the sacrum, to the spinous processes of the lumbar and three lower dorsal ver- tebra, and the supraspinous ligament; externally, to the back part of the inner lip of the crest of the ilium, and to the series of eminences on the posterior part of the sacrum, representing the transverse processes, Avhere it blends Avith the great sacro-sciatic ligament. The muscular fibres thus arising form a single large muscular mass, bounded in front by the transverse processes of the lumbar ver- tebra, and by the middle lamella of the fascia of the Transversalis muscle. Oppo- site the last rib, this mass divides into tAvo parts, one external, the Sacro-lumbalis, the other internal and larger, the Longissimus dorsi. The Sacro-lumbalis, the external and smaller portion of the Erector spina, is inserted, by a series of separate tendons, into the angles of the six lower ribs. If this muscle is reflected outAvards, it will be seen to be reinforced by a series of muscular slips, which arise from the angles of the ribs ; by means of these the Sacro-lumbalis is continued upAvards, to be connected with the upper ribs, and with the cervical portion of the spine, forming tAvo additional muscles, the Mus- culus accessorius and the Cervicalis ascendens. The Musculus Accessorius ad Sacro-lumbalem arises by separate flattened ten- dons, from the upper margins of the angles of the six lower ribs ; these become muscular, and are finally inserted, by separate tendons, into the angles of the six upper ribs. The Cervicalis Ascendens is the continuation of the Sacro-lumbalis upAvards into the neck: it is situated on the inner side of the tendons of the Accessorius, arising from the angles of the four or five upper ribs, and is inserted, by a series of slender tendons, into the posterior tubercles of the transverse processes of the fourth, fifth, and sixth cervical vertebra. Longissimus Dorsi. The inner portion of the Erector spina, the larger and longer of the two, has received the name " Longissimus dorsi." It arises, Avith the Sacro-lumbalis, from the common origin already mentioned. In the lumbar region, Avhere it is as yet blended Avith the Sacro-lumbalis, some of the fibres are directed forwards, to be inserted into the posterior surface of the transverse processes of the lumbar vertebra their whole length, into the tubercles at the back of the articular processes, and into the layer of lumbar fascia connected with the apices of the transverse processes. In the dorsal region, the Longissimus dorsi is inserted, by long and thin tendons, into the extremities of the transverse processes of all the dorsal vertebra, and into from seven to eleven ribs between their tubercles and angles. This muscle is continued upwards to the cranium and cervical portion of the spine, by means of two additional slender fasciculi, the Transversalis colli, and Trachelo-mastoid. The Transversalis Colli, placed on the inner side of the Longissimus dorsi, arises, by long, thin tendons, from the summit of the transverse processes of the third, fourth, fifth, and sixth dorsal vertebra, and is inserted, by similar tendons, into the posterior tubercles of the transverse processes of the five Ioavci* cervical. The Trachelo-iui posterior surface, in the fore- arm, Avith the ulna, the inter- osseous ligament, the Pronator quadratus ; and, in the hand, with the Interossei, Adductor pollicis, and deep palmar arch. By its ulnar border, Avith the Flexor carpi ulnaris. By its radial border, Avith the Flexor longus pollicis, the anterior interosseous artery and nerve being interposed. The Flexor Longus Pollicis is situated on the radial side of the forearm, lying on the same plane as the preceding. It arises from the upper two- thirds of the grooved anterior surface of the shaft of the radius; commencing, above, immediately beloAV the tubero- sity and oblique line, and ex- tending, beloAV, to within a short distance of the Pronator quadratus. It also arises from the adjacent part of the inter- osseous membrane, and occa- sionally by a fleshy slip from the inner side of the base of the coronoid process. The fibres pass downAvards, and terminate in a flattened ten- don, which passes beneath the annular ligament, is then lodged in the interspace be- tween the two heads of the Flexor brevis pollicis, and, entering a tendino-osseous ca- nal, similar to those for the other flexor tendons, is in- serted into the base of the last phalanx of the thumb. Relations. By its anterior surface, with the Flexor sub- limis digitorum, Flexor carpi radialis, Supinator longus, and radial vessels. By its poste- rior surface, with the radius, interosseous membrane, and Pronator Quadratus. By its ulnar border, with the Flexor profundus digitorum, from which it is separated by the anterior interosseous artery and nerve. The Pronator Quadratus is a small muscle, quadrilateral Fig. 156.—Front of the Left Forearm. Deep Muscles. 258 MUSCLES AND FASCIJE. in form, extending transversely across the radius and ulna, immediately above their carpal extremities. It arises from the oblique line on the loAver fourth of the anterior surface of the shaft of the ulna, and the surface of bone immediately beloAv it; from the internal border of the ulna; and from a strong aponeurosis which covers the inner third of the muscle. The fibres pass horizontally outAvards, to be inserted into the lower fourth of the anterior surface and external border of the shaft of the radius. Relations. By its anterior surface, with the Flexor profundis digitorum, the Flexor longus pollicis, Flexor carpi radialis, and the radial and ulnar vessels, and ulnar nerve. By its posterior surface, Avith the radius, ulna, and interosseous membrane. Nerves. All the muscles of the superficial layer are supplied by the median nerve, excepting the Flexor carpi ulnaris, Avhich is supplied by the ulnar. Of the deep layer, the Flexor profundis digitorum is supplied conjointly by the ulnar and anterior interosseous nerves, the Flexor longis pollicis and Pronator quadratus by the anterior interosseous nerve. Actions. These muscles act upon the forearm, the Avrist, and hand. Those acting on the forearm are the Pronator radii teres and Pronator quadratus, Avhich rotate the radius upon the ulna, rendering the hand prone; Avhen pronation has been fully effected, the Pronator radii teres assists the other muscles in flexing the forearm. The flexors of the wrist are the Flexor carpi ulnaris and radialis ; and the flexors of the phalanges are the Flexor sublimis and profundus digitorum ; the former flexing the second phalanges, and the latter the last. The Flexor longus pollicis flexes the last phalanx of the thumb. The three latter muscles, after flexing the phalanges by continuing their action, act upon the Avrist, assisting the ordinary flexors of this joint; and all assist in flexing the forearm upon the arm. The Palmaris longus is a tensor of the palmar fascia; Avhen this action has been fully effected, it flexes the hand upon the forearm. .Radial Region. Supinator Longus. Extensor Carpi Radialis Longior. Extensor Carpi Radialis Brevior. Dissection. Divide the integument in the same manner as in the dissection of the ante- rior brachial region; and, after having examined the cutaneous vessels and nerves, and deep fascia, they should be removed, when the muscles of this region will be exposed. The removal of the fascia will be considerably facilitated by detaching it from below upwards. Great care should be taken to avoid cutting across the tendons of the muscles of the thumb. The Supinator Longus is the most superficial muscle on the radial side of the forearm, fleshy for the upper two-thirds of its extent, tendinous below. It arises from the upper two-thirds of the external condyloid ridge of the humerus, and from the external intermuscular septum, being limited above by the musculo-spiral groove. The fibres descend on the anterior and outer side of the forearm, and terminate in a flat tendon, which is inserted into the base of the styloid process of the radius. Relations. By its superficial surface, with the integument and fascia for the greater part of its extent; near its insertion it is crossed by the Extensor ossis metacarpi pollicis and the Extensor primi internodii pollicis. By its deep surface, Avith the humerus, the Extensor carpi radialis longior and brevior, the insertion of the Pronator radii teres, and the Supinator brevis. By its inner border, above the elbow, with the Brachialis anticus, the musculo-spiral nerve, and radial recurrent artery; and, in the forearm, Avith the radial vessels and nerve. The Extensor Carpi Radialis Longior is placed partly beneath the preceding muscle. It arises from the lower third of the external condyloid ridge of the humerus, immediately below the Supinator longus, and from the external inter- muscular septum. The fibres pass downwards, and terminate at the upper third of the forearm in a flat tendon, which runs along the outer border of the radius, RADIAL REGION. 259 beneath the extensor tendons of the thumb ; it then passes through a groove common to it and the Extensor carpi radialis brevior, immediately behind the styloid process; and is inserted into the base of the metacarpal bone of the index finger, its radial side. Relations. By its superfi- cial surface, Avith the Supi- nator longus and fascia of the forearm. Its outer side, is crossed obliquely by the Ex- tensor ossis metacarpi pollicis and the Extensor primi inter- nodii pollicis ; and at the Avrist by the Extensor secundi inter- nodii pollicis. By its deep surface, Avith the elbow joint, the Extensor carpi radialis brevior, and back part of the wrist. The Extensor Carpi Radi- alis Brevior is shorter, as its name implies, and thicker than the preceding muscle, beneath which it is placed. It arises from the external condyle of the humerus by a tendon common to it and the other extensor muscles ; from the external lateral ligament of the elbow joint ; from a strong aponeurosis Avhich co- vers its surface ; and from the intermuscular septum betAveen it and the adjacent muscles. The fibres pass doAvmvards, and terminate about the mid- dle of the forearm in a flat tendon, Avhich is closely con- nected Avitli that of the pre- ceding muscle, accompanies it to the Avrist, lying in the same groove on the posterior surface of the radius ; passes beneath the annular ligament, and di- verging someAvhat from its fellow, is inserted into the base of the metacarpal bone of the middle finger, its radial side. The tendons of the tAvo preceding muscles, as they pass across the same groove at the back of the radius, arc Fig. 157.—Posterior Surface of Forearm. Superficial Muscles. 260 MUSCLES AND FASCRE. retained in it by a fibrous sheath, lubricated by a single synovial membrane but separated from each other by a small vertical ridge of bone. Relations. By its superficial surface, Avith the Extensor carpi radialis longior and crossed by the Extensor muscles of the thumb. By its deep surface, Avith the Supinator brevis, tendon of the Pronator radii teres, radius, and Avrist joint. Bv its ulnar border, Avith the Extensor communis digitorum. Posterior Brachial Region. Superficial Layer. Extensor Communis Digitorum. Extensor Carpi Ulnaris. Extensor Minimi Digiti. Anconeus. The Extensor Communis Digitorum is situated at the back part of the forearm. It arises from the external condyle of the humerus by a tendon common to it and the other superficial Extensor muscles, from the deep fascia, and the inter- muscular septa betAveen it and the adjacent muscles. Just beloAv the middle of the forearm it divides into four tendons, Avhich pass in a separate sheath beneath the posterior annular ligament of the wrist, lubricated by a synovial membrane. The tendons then diverge, the two middle ones passing along the dorsal surface of the corresponding metacarpal bones, the lateral ones crossing obliquely to the metacarpal bones, along which they pass; and are finally inserted into the second and third phalanges of the fingers in the folloAving manner: Each tendon opposite its corresponding metacarpo-phalangeal articulation becomes narrow and thickened, being reinforced by the tendons of the interossei and lumbricales, gives off a thin fasiculus upon each side of the joint, and spreads out into a broad aponeurosis, Avhich covers the Avhole of the dorsal surface of the first phalanx. Opposite the first phalangeal joint, this aponeurosis divides into three slips, a middle and two lateral; the former is inserted into the base of the second phalanx, and the two lateral, Avhich are continued onwards along the sides of the second phalanx, unite by their contiguous margins, and are inserted into the upper surface of the last phalanx. The tendons of the middle, ring, and the little fingers are connected together as they cross the hand by small oblique tendinous slips. The tendons of the index and little fingers also receive, before their division, the special extensor tendons belonging to them. Relations. By its superficial surface, with the fascia of the forearm and hand, the posterior annular ligament and integument. By its deep surface, with the Supinator brevis, the Extensor muscles of the thumb and index finger, posterior interosseous artery and nerve, the wrist joint, carpus, metacarpus, and phalanges. By its radial border, with the Extensor carpi radialis brevior. By its ulnar border, with the Extensor minimi digiti, and Extensor carpi ulnaris. The Extensor Minimi Digiti is a small slender muscle, placed on the inner side of the Extensor communis, with which it is generally connected. It arises from the common tendon of origin of the Extensor muscles by a thin tendinous slip; and from the intermuscular septa between it and the adjacent muscles. Passing down to the lower extremity of the ulna, its tendon runs through a separate sheath in the annular ligament, and at the metacarpo-phalangeal articulation unites with the tendon derived from the long Extensor. The common tendon then spreads into a broad aponeurosis, which is inserted into the second and third pha- langes of the little finger in a similar manner to the common extensor tendons of the other fingers. The Extensor Carpi Ulnaris is the most superficial muscle on the ulnar side of the forearm. It arises by the common tendon from the external condyle of the humerus, from the middle third of the posterior border of the ulna below the An- coneus, and from the fascia of the forearm. This muscle terminates in a tendon, which runs through a groove behind the styloid process of the ulna, passes through POSTERIOR BRACHIAL REGION. 261 a separate sheath in the annular ligament, and is inserted into the base of the metacarpal bone of the little finger. Relations. By its superficial surface, with the fascia of the forearm. By its deep surface, Avith the ulna, and the muscles of the deep layer. The Anconeus is a small triangular muscle, placed behind and beneath the elbow joint; and appears to be a continuation of the external portion of the Triceps. It arises by a separate tendon from the back part of the outer condyle of the humerus; the fibres diverge from this origin, the upper ones being directed horizontally, the lower obliquely inwards, to be inserted into the triangular surface at the upper part of the posterior surface of the shaft of the ulna. Relations. By its superficial surface, with a strong fascia derived from the Tri- ceps. By its deep surface, Avith the elboAv joint, the orbicular ligament, the ulna, and a small portion of the Supinator brevis. Posterior Brachial Region. Deep Layer. Supinator Brevis. Extensor Primi Internodii Pollicis. Extensor Ossis Metacarpi Pollicis. Extensor Secundi Internodii Pollicis. Extenso Indicis. The Supinator Brevis is a broad muscle, of a hollow cylindrical form, curved around the upper third of the radius. It arises from the external condyle of the humerus, from the external lateral ligament of the elbow joint, from the orbicular ligament of the radius, from the prominent oblique line of the ulna, extending down from the loAver extremity of the lesser sigmoid cavity, and the triangular depression in front of it; it also arises from a tendinous expansion which covers its surface. The fibres of the muscle pass obliquely around the upper part of the radius ; the most superior fibres forming a sling-like fasciculus, which passes around the neck of the radius above the tuberosity, to be attached to the back part of its inner surface ; the middle fibres being attached to the outer edge of the bicipital tuberosity ; the lower fibres to the oblique line as low down as the insertion of the Pronator radii teres. This muscle is pierced by the posterior interosseous nerve. Relations. By its superficial surface, with the Pronator radii teres, all the su- perficial Extensor and Supinator muscles, the Anconeus, the radial vessels and nerve, and the musculo-spiral nerve. By its deep surface, Avith the elbow joint, the interosseous membrane, and the radius. The Extensor Ossis Metacarpi Pollicis is the most external and the largest of the deep Extensor muscles, lying immediately below the Supinator brevis. It arises from the posterior surface of the shaft of the ulna beloAV the origin of the Supinator brevis, from the interosseous ligament, and from the middle third of the posterior surface of the shaft of the radius. Passing obliquely down- wards and outAvards, it terminates in a tendon Avhich runs through a groove on the outer side of the styloid process of the radius, accompanied by the tendon of the Extensor primi internodii pollicis, and is inserted into the base of the metacarpal bone of the thumb. Relations. By its sup>erficial surface, Avith the Extensor communis digitorum, Extensor minimi digiti, and fascia of the forearm; being crossed by the branches of the posterior interosseous artery and nerve. By its deep surface, Avith the ulna, interosseous membrane, radius, the tendons of the Extensor carpi radialis longior and brevior, and at the outer side of the Avrist with the radial artery. By its iqyper border, Avith the Supinator brevis. By its lower border, with the Ex- tensor primi internodii pollicis. The Extensor Primi Internodii Pidlicis is much smaller than the preceding muscle, on the inner side of which it lies. It arises from the posterior surface of the shaft of the radius, immediately beloAv the Extensor ossis metacarpi, and from the interosseous membrane. Its direction is similar to that of the Exten- sor ossis metacarpi, its tendon passing through the same groove on the outer side 2G2 MUSCLES AND FASCIAE. of the styloid process, to be inserted into the base of the first phalanx of the thumb. Relations. The same as those of the Extensor ossis metacarpi pollicis. The Extensor Secundi Internodii Pollicis is much larger than the preceding Fig. 158.—Posterior Surface of the Forearm. Deep Muscles. muscle, the origin of which it partly covers in. It arises from the posterior surface of the shaft of the ulna, below the origin of the Extensor ossis metacarpi pollicis, and from the interosseous mem- brane. It terminates in a tendon which passes through a distinct canal in the annu- lar ligament, lying in a nar- row oblique groove at the back part of the lower end of the radius. It then crosses obliquely the tendons of the Extensor carpi radialis lon- gior and brevior, being sepa- rated by a triangular interval from the other Extensor ten- dons of the thumb, in Avhich space the radial artery is found ; and is finally inserted into the base of the last pha- lanx of the thumb. Relations. By its super- ficial surface, Avith the same parts as the Extensor ossis metacarpi pollicis. By its deep surface, Avith the ulna, interosseous membrane, radius, the Avrist, the radial artery, and metacarpal bone of the thumb. The Extensor Indicis is a narroAv, elongated muscle, placed on the inner side of, and parallel with, the pre- ceding. It arises from the posterior surface of the shaft of the ulna beloAV the origin of the Extensor secundi inter- nodii pollicis, and from the interosseous membrane. Its tendon passes with the Ex- tensor communis digitorum through the same canal in the annular ligament, and subse- quently joins that tendon of the Extensor communis which belongs to the index finger, opposite the lower end of the corresponding metacarpal bone. It is finally inserted OF THE HAND. 263 into the second and third phalanges of the index finger, in the manner already described. Relations. They are similar to those of the preceding muscles. Nerves. The Supinator longus, Extensor carpi radialis longior, and Anconeus, are supplied by branches from the musculo-spiral nerve. The remaining muscles of the radial and posterior brachial regions, by the posterior interosseous nerve. Actions. The muscles of the radial and posterior brachial regions, which com- prise all the Extensor and Supinator muscles, act upon the forearm, Avrist, and hand ; they are the direct antagonists of the Pronator and Flexor muscles. The Anconeus assists the Triceps in extending the forearm. The Supinator longus and brevis are the supinators of the forearm and hand ; the former muscle more especially acting as a supinator Avhen the limb is pronated. When supination has been produced, the Supinator longus, if still continuing to act, flexes the forearm. The Extensor carpi radialis longior and brevior, and Extensor carpi ulnaris muscles, are the Extensors of the wrist; continuing their action, they serve to extend the forearm upon the arm; they are the direct antagonists of the Flexor carpi radialis and ulnaris. The common Extensor of the fingers, the Extensors of the thumb, and the Extensors of the index and little fingers, serve to extend the pha- langes into which they are inserted; and are the direct antagonists of the Flexors. By continuing their action they assist in extending the forearm. The Extensors of the thumb may assist in supinating the forearm, when this part of the hand has been draAvn inAvards towards the palm, on account of the oblique direction of the tendons of these muscles. Muscles and Fascle of the Hand. Dissection (Fig. 151). Make a transverse incision across the front of the wrist, and a second across the heads of the metacarpal bones, connect the two by a vertical incision in the middle line, and continue it through the centre of the middle finger. The anterior and posterior annular ligaments, and the palmar fascia, should first be dissected. The Anterior Annular Ligament is a strong fibrous band, which arches over the front of the carpus, converting the deep groove on the front of these bones into a canal, beneath Avhich the tendons of the muscles of the forearm pass, pre- vious to their insertion into the fingers. This ligament is attached, internally, to the pisiform bone, and unciform process of the unciform; and externally, to the tuberosity of the scaphoid, and ridge on the trapezium. It is continuous, above, Avith the deep fascia of the forearm, and beloAv, with the palmar fascia. It is crossed by the tendon of the Palmaris longus, by the ulnar artery and nerve, and the cutaneous branch of the median nerve. It has inserted into its upper and inner part, the tendon of the Flexor carpi ulnaris; and has, arising from it beloAV, the small muscles of the thumb and little finger. It is pierced by the tendon of the Flexor carpi radialis; and, beneath it, pass the tendons of the Flexor sublimis and profundus digitorum, the Flexor longus pollicis, and the median nerve. There are tAvo synovial membranes beneath this ligament; one of large size, in- closing the tendons of the Flexor sublimis and profundus ; and a separate one for the tendon of the Flexor longus pollicis; the latter is also large and very ex- tensive, reaching from above the wrist to the extremity of the last phalanx of the thumb. The Posterior Annular Ligament is a strong transverse fibrous band, extending across the back of the Avrist, and continuous with the fascia of the forearm. It forms a sheath for the extensor tendons in their passage to the fingers, being attached, internally, to the cuneiform and pisiform bones, and palmar fascia ; ex- ternally, to the margin of the radius ; and in its passage across the wrist, to the elevated ridges on the posterior surface of the radius. It presents six compartments for the passage of tendons, each of which is lined by a separate synovial sac. These are, from within outAvards, 1. A sheath on the outer side of the radius for the tendons of the Extensor ossis metacarpi, and Extensor primi internodii pollicis. 2. Behind the styloid process, for the tendons 261 MUSCLES AND FASCIA. of the Extensor carpi radialis longior and brevior. 3. Opposite the middle of the posterior surface of the radius, for the tendon of the Extensor secundi internodii pollicis. 4. For the tendons of the Extensor communis digitorum, and Extensor indicis. 5. For the Extensor minimi digiti. 6. For the tendon of the Extensor carpi ulnaris. The synovial membranes lining these sheaths are usually very ex- tensive, extending from above the annular ligament, doAvn upon the tendons, al- most to their insertion. The Palmar Fascia forms a common sheath which invests the muscles of the hand. It consists of three portions, a central and tAvo lateral. The central por- tion occupies the middle of the palm, is triangular in shape, of great strength and thickness, and binds down the tendons in this situation. It is narrow above, being attached to the lower margin of the annular ligament, and receives the expanded tendon of the Palmaris longus muscle. Below, it is broad and expanded, and op- posite the heads of the metacarpal bones divides into four slips, for the four fingers. Each slip subdivides into two processes Avhich inclose the tendons of the Flexor muscles, and are attached to the sides of the first phalanx, and to the anterior or glenoid ligament; by this arrangement, four arches are formed, under Avhich the Flexor tendons pass. The arched intervals left in the fascia betAveen these four fibrous slips, transmit the digital vessels and nerves, and the tendons of the Lum- bricales. At the point of division of the palmar fascia into the slips above men- tioned, numerous strong transverse fibres bind the separate processes together. This fascia is intimately adherent to the integument by numerous fibrous bands, and gives origin by its inner margin to the Palmaris brevis ; it covers the superficial palmar arch, the tendons of the Flexor muscles, and the branches of the median and ulnar nerves ; and on each side it gives off a vertical septum, Avhich is con- tinuous Avith the interosseous aponeurosis, and separates the lateral from the middle palmar region. The lateral portion of the palmar fascia are very thin fibrous layers, Avhich cover, on the radial side, the muscles of the ball of the thumb; and on the ulnar side, the muscles of the little finger; they are continuous with the dorsal fascia, and in the palm, with the middle portion of the palmar fascia. Muscles of the Hand. The muscles of the hand are subdivided into three groups. 1. Those of the thumb, which occupy the radial side. 2. Those of the little finger, which occupy the ulnar side. 3. Those in the middle of the palm and betAveen the interosseous spaces. Radial Group. Muscles of the Thumb. Abductor Pollicis. Opponens Pollicis (Flexor Ossis Metacarpi). Flexor Brevis Pollicis. Adductor Pollicis. The Abductor Pollicis is a thin, flat, narrow muscle, placed immediately be- neath the integument. It arises from the ridge of the os trapezium and annular ligament; and passing outwards and doAvmvards, is inserted by a thin flat tendon into the radial side of the base of the first phalanx of the thumb. Relations. By its superficial surface, with the palmar fascia. By its deep sur- face,^ Avith the Opponens pollicis, from Avhich it is separated by a thin aponeurosis. Its inner border is separated from the Flexor brevis pollicis by a narrow cellular interval. The Opponens Pollicis (Flexor Ossis Metacarpi) is a small triangular muscle, placed beneath the preceding. It arises from the palmar surface of the trapezium and annular ligament; the fleshy fibres pass downwards and outwards, to be inserted into the whole length of the metacarpal bone of the thumb on its radial side. Relations. By its superficial surface, Avith the Abductor pollicis. By its deep OF THE HAND. 265 surface, Avith the trapezio-metacarpal articulation. By its inner border, with the Flexor brevis pollicis. The Flexor Brevis Pollicis is much larger than either of the tAvo preceding muscles, beneath Avhich it is placed. It consists of two distinct portions, in the interval between which lies the tendon of the Flexor longus pollicis. The ante- rior and more superficial portion arises from the trapezium and outer tAvo-thirds of the annular ligament; the deeper portion from the trapezoides, os magnum, base Fig. 159.—Muscles of the Left Hand. Palmar Surface. of the third metacarpal bone, and sheath of the tendon of the Flexor carpi radialis. The fleshy fibres unite to form a single muscle ; this divides into tAvo tendons, 266 MUSCLES AND FASCIA. which are inserted one on either side of the base of the first phalanx of the thumb. A sesamoid bone is developed in each of these tendons as they pass across the me- tacarpo-phalangeal joint; the outer one being joined by the tendon of the Abduc- tor, and the inner by that of the Adductor. Relations. By its superficial surface, with the palmar fascia. By its deep surface, with the Adductor pollicis, and tendon of the Flexor carpi radialis. By its external surf ace, with the Opponens pollicis. By its interned surface, with the tendon of the Flexor longus pollicis. The Adductor Pollicis (Fig. 156), is the most deeply seated and the largest of this group of muscles. It is of a triangular form, arising, by its broad base, from the whole length of the metacarpal bone of the middle finger on its palmar surface: the fibres, proceeding outwards, converge to be inserted by a short tendon into the ulnar side of the base of the first phalanx of the thumb, and into the internal sesamoid bone, being blended with the innermost tendon of the Flexor brevis pollicis. Relations. By its superficial surface, Avith the Flexor brevis pollicis, the tendons of the Flexor profundus digitorum and Lumbricales. Its deep surface covers the two first interosseous spaces, from which it is separated by a strong aponeurosis. Nerves. The Abductor, Opponens, and outer head of the Flexor brevis pollicis, are supplied by the median nerve; the inner head of the Flexor brevis, and the Adductor pollicis, by the ulnar nerve. Actions. The actions of the muscles of the thumb are almost sufficiently indi- cated by their names. This segment of the hand is provided with three Extensors, an Extensor, of the metacarpal bone, an Extensor of the first, and an Extensor of the second phalanx; these occupy the dorsal surface of the forearm and hand. There are, also, three Flexors on the palmar surface, a Flexor of the metacarpal bone, the Flexor ossis metacarpi (Opponens pollicis), the Flexor brevis pollicis, and the Flexor longus pollicis ; there is also an Abductor and an Adductor! These muscles give to the thumb that extensive range of motion which it pos- sesses in an eminent degree. Ulnar Region. Muscles of the Little Finger. Palmaris Brevis. Flexor Brevis Minimi Digiti. Abductor Minimi Digiti. Opponens Minimi Digiti.& _ The Palmaris Brevis is a thin quadrilateral plane of muscular fibres, placed immediately beneath the integument on the ulnar side of the hand. It arises by tendinous fasciculi, from the annular ligament and palmar fascia ; the fleshy fibres pass horizontally inwards, to be inserted into the skin on the inner border ot the palm of the hand. Relations. By its superficial surface, with the integument to which it is inti- mately adherent, especially by its inner extremity. By its deep surface, with the inner portion of the palmar fascia, which separates it from the ulnar artery and nerve, and from the muscles of the ulnar side of the hand. The Abductor Minimi Digiti is situated on the ulnar border of the palm of the hand. It arises by tendinous fibres from the pisiform bone, and from an expan- sion ot the tendon of the Flexor carpi ulnaris. The muscle terminates in a flat tendon, which is inserted into the base of the first phalanx of the little finger, on its ulnar side. Relations. By its superficial surface, with the inner portion of the palmar tascia, and the Palmaris brevis. By its deep surface, Avith the Flexor ossis meta- C'drrvl' vJ ltS mner horder> with tlie ^exor brevis minimi digiti. lire Ilexor Brevis Minimi Digiti lies on the same plane as the preceding muscle, on its radial side. It arises from the unciform process of the unciform OF THE HAND. 267 bone, and anterior surface of the annular ligament, and is inserted into the base of the first phalanx of the little finger, in connection with the preceding. It is separated from the Abductor at its origin, by the communicating branch of the ulnar artery, and deep palmar branch of the ulnar nerve. This muscle is some- times wanting. The Abductor is then, usually, of large size. Relations. By its superficial surface, with the internal portion of the palmar fascia, and the Palmaris brevis. By its deep surface, with the Flexor ossis meta- carpi. The Opponens Minimi Digiti (Fig. 150), is of a triangular form, and placed im- mediately beneath the preceding muscles. It arises from the unciform process of the unciform bone, and contiguous portion of the annular ligament; from these points, the fibres pass downwards and inwards, to be inserted into the Avhole length of the metacarpal bone of the little finger, along its ulnar margin. Relations. By its superficial surface, with the Flexor brevis, and Abductor minimi digiti. By its deep surface, with the interossei muscles in the fourth metacarpal space, the metacarpal bone, and the Flexor tendons of the little finger. Nerves. All the muscles of this group are supplied by the ulnar nerve.' Actions. The actions of the muscles of the little finger are expressed in their names. The Palmaris breAls corrugates the skin on the inner side of the palm of the hand. Middle Palmar Region. Lumbricales. Interossei Palmares. Interossei Dorsales. The Lumbricales are four small fleshy fasciculi, accessories to the deep Flexor muscle. They arise by fleshy fibres from the tendons of the deep Flexor, the first and second, from the radial side and palmar surface of the tendons of the index and middle fingers ; the third, from the contiguous sides of the tendons of the middle and ring fingers; and the fourth, from the contiguous sides of the tendons of the ring and little fingers. They pass forwards to the radial side of the cor- responding fingers, and opposite the metacarpo-phalangeal articulations, each tendon terminates in a broad aponeurosis, which is inserted into the tendinous ex- pansion from the Extensor communis di- gitorum, Avhich covers the dorsal aspect of each finger. The Interossei Muscles are so named from their occupying the intervals be- tAveen the metacarpal bones. They are divided into tAvo sets, a dorsal and pal- mar ; the former are four in number, one- in each metacarpal space, the latter, three in number, lie upon the metacarpal bones. The Dorsetl Interossei are four in number, larger than the palmar, and occupy the intervals between the meta- carpal bones. They are bipenniform muscles, arising by tAvo heads from the adjacent sides of the metacarpal bones, but more extensively from that side of the metacarpal bone which corresponds to the side of the finger in Avliich the muscle is inserted. They are inserted Fig. 10i).—The Dorsal Interossei of Left Hand. 268 SURGICAL ANATOMY. Hand. into the base of the first phalanges, and into the aponeurosis of the common Extensor tendon. BetAveen the double origin of each of these muscles is a narroAv triangular interval, through Avhich passes a perforating branch from the deep palmar arch. The First Dorsal Interosseous muscle, or Abductor indicis, is larger than the others, and lies in the interval between the thumb and index finger. It is fiat, triangular in form, and arises by tAvo heads, separated by a fibrous arch, for the passage of the radial artery into the deep part of the palm of the hand. The outer head arises from the upper half of the ulnar border of the first metacarpal bone; the inner head, from the entire length of the radial border of the second metacarpal bone; the tendon is inserted into the radial side of the index finger. The second and third are inserted into the middle finger, the former into its radial, the latter into its ulnar side. The fourth is inserted in the radial side of the ring finger. The Palmar Interossei, three in number, are smaller than the Dorsal, and placed v\„ id T-i t> i t . • rt r upon the palmar surface of the metacarpal rig. 161.—The Palmar Interossei of Left 1*111 ' bones, rather than betAveen them. Thev arise from the entire length of the meta- carpal bone of one finger, and are inserted into the side of the base of the first pha- lanx and aponeurotic expansion of the com- mon Extensor tendon of the same finger. The first arises from the ulnar side of the second metacarpal bone, and is inserted into the same side of the index finder. The second arises from the radial side of the fourth metacarpal bone, and is inserted into the same side of the ring finger. The third arises from the radial side of the fifth me- tacarpal bone, and is inserted into the same side of the little finger. From this account it may be seen, that each finger is provided with two Interossei muscles, with the excep- tion of the little finger. Nerves. The tAvo outer Lumbricales are supplied by the median nerve; the rest of the muscles of this group by the ulnar. Actions. The Dorsal interossei muscles abduct the fingers from an imaginary line drawn longitudinally through the centre of the middle finger, and the Palmar interossei abduct the fingers towards the same line. They usually assist the Extensor muscles, but when the fingers are slightly bent, assist in flexing the fingers. SURGICAL ANATOMY. The student having completed the dissection of the muscles of the upper ex- tremity, should consider the effects likely to be produced by the action of the various muscles in fracture of the bones; the causes of displacement are thus easily recognized, and a suitable treatment in each case may be readily adopted. In considering the actions of the various muscles*upon fractures of the upper extremity, the most common forms of injury have been selected, both for illustra- tion and description. Fracture of the clavicle is an exceedingly common accident, and is usually caused by indirect violence, as a fall upon the shoulder; it occasionally, however, occurs from direct force. Its most usual situation is just external to the centre of the bone, but it may occur at the sternal or acromial ends. Fracture of the middle of the clavicle (Fig. 162) is always attended with con- OF THE MUSCLES OF THE UPPER EXTREMITY. 269 siderable displacement, the outer fragment being draAvn downwards, forwards, and inwards ; the inner fragment slightly upAvards, the outer fragment is drawn down by the weight of the arm and the action of the Deltoid, and forwards and inwards by Fig- if>2.—Fracture of the Middle of the the Pectoralis minor and Subclavius muscles; the inner fragment is slightly raised by the Sterno-cleido-mastoid, but only to a very limited extent, as the attachment of the costo-clavicular ligament and Pectoralis major beloAV and in front Avould prevent any very great displacement upwards. The causes of displacement having been ascer- tained, it is easy to apply the appropriate treatment. The outer fragment is to be draAvn outAvards, and, together with the scapula, raised upAvards to a level with the inner fragment, and retained in that posi- tion. In fracture of the acromial end of the clavicle betAveen the conoid and trapezoid ligaments, only slight displacement occurs, as these ligaments, from their oblique inser- tion, serve to hold both portions of the bone in apposition. Fracture, also, of the sternal end, internal to the costo-clavicular ligament, is attended Avith only slight displacement, this ligament serving to retain the fragments in close apposition. Fracture of the acromion process usually arises from violence applied to the upper and outer part of the shoulder : it is generally known by the rotundity of the shoulder being lost, from the Deltoid draAving downwards and forAvards the fractured portion ; and the displacement may easily be discovered by tracing the margin of the clavicle outwards, Avhen the fragment will be found resting on the front and upper part of the head of the humerus. In order to relax the anterior and outer fibres of the Deltoid (the opposing muscle), the arm should be drawn forwards across the chest, and the elbow well raised up, so that the head of the bone may press upwards the acromion process, and retain it in its position. Fracture of the coracoid process is an extremely rare accident, and is usually caused by a sharp blow directly on its pointed extremity. Displacement is here produced by the combined actions of the Pectoralis minor, short head of the Biceps, and" Coraco-brachialis, the former muscle drawing the fragment inwards, the latter directly downwards, the amount of displacement being limited by the connection of this process to the acromion by means of the coraco-acromial liga- ment. In order to relax these muscles, and replace the fragment in close appo- sition, the forearm should be flexed so as to relax the Biceps, and the arm drawn forwards and inAvards across the chest so as to relax the Coraco-brachialis ; the action of the Pectoralis minor may be counteracted by placing a pad in the axilla; the humerus should then be pushed upwards against the coraco-acromial ligament, and the arm retained in this position. Fracture of the anatomical neck of the humerus within the capsular ligament is a rare accident, attended with very slight displacement, an impaired condition of the motions of the joint, and crepitus. Fracture of the surgical neck (Fig. 163) is very common, is attended with con- siderable displacement, and its appearances correspond somewhat with those of dislocation of the head of the humerus into the axilla. The upper fragment is slightly elevated under the coraco-acromial ligament by the muscles attached to 270 SURGICAL ANATOMY. the greater and lesser tuberosities ; inwards by the Pectoralis major, Fig. 103.—Fracture of the Surgical Neck of the Humerus. the upper end of the Ioavci- fragment is drawn Latissimus dorsi, and Teres major; and the humerus is thrown obliquely outAvards from the side by the action of the Deltoid, and occasionally elevated so as to project beneath and in front of the coracoid process. B fixing the shoulder, and drawing the outAvards and doAvmvards, the formity is at once reduced. To y arm existing de- counteract the action of the opposing muscles, and to keep the fragments in position, the arm should be draAvn from the side, and paste- board splints applied on its four sides, a large conical-shaped pad should be placed in the axilla Avith the base turned upwards and the elboAv approximated to the side, and retained there by a broad roller passed around the chest; by these means, the action of the Pectoralis major, Latissimus dorsi, Teres major, and Deltoid muscles is coun- teracted : the forearm should then be. flexed, and the hand supported in a sling, care being taken not to raise the elbow, otherwise, the loAver fragment may be dis- placed upAvards. In fracture of the shaft of the humerus below the insertion of the Pectoralis major, Latissimus dorsi, and Teres major, and above the insertion of the Deltoid, there is also considerable deformity, the loAver end of the upper fragment being drawn inwards, by the first-mentioned muscles, and the lower fragment draAvn up- Avards and outAvards by the Deltoid, producing shortening of the limb, and a con- siderable prominence at the seat of fracture, from the fractured ends of the bone riding over one another, especially if the fracture takes place in an oblique direc- tion. The fragments may be readily brought into apposition by extension from the elboAv, and retained in that position by adopting the same means as in the preceding injury. In fracture of the shaft of the humerus immediately beloiv the insertion of the Deltoid, the amount of deformity depends greatly upon the direction of the fracture. If the fracture occurs in a transverse direction, only slight displacement occurs, the lower extremity of the upper fragment being drawn a little forwards; but in oblique fracture, the combined actions of the Biceps and Brachialis anticus muscles upfront, and the Triceps behind, draw upwards the lower fragment, causing it to glide oyer the lower end of the upper fragment, either backwards or forwards, according to the direction of the fracture. Simple extension reduces the defor- mity, and the application of splints on the four sides of the arm retains the frag- ments in apposition. Care should be taken not to raise the elbow, but the forearm and hand may be supported in a sling. Fracture of the humerus immediately above the condyles (Fig. 164) deserves very attentive consideration, as the general appearances correspond somewhat with those produced by separation of the epiphysis of the humerus, and with those of dislocation of the radius and ulna backwards. If the direction of the fracture s oblique from above, downwards and outAvards, the lower fragment is drawn upwards and backwards by the Brachialis anticus and Biceps in front, and the Iriceps behind. This injury may be diagnosed from dislocation by the increased mobility in fracture, the existence of crepitus, and the deformity being remedied by extension, by the discontinuance of which it is again reproduced. The age of the patient is of importance in distinguishing this form of injury from separation of the epiphysis. If fracture occurs in the opposite direction to that shown in the plate, the lower fragment is drawn upwards and forwards, causing a con- OF THE MUSCLES OF THE UPPER EXTREMITY. 271 Fig. 164.—Fracture of the Humerus above the Condyles, siderable prominence in front, and the loAver end of the upper fragment projects backAvards beneath the tendon of the Triceps muscle. Fracture of the coronoid process of the ulna is an accident of rare occurrence, and is usually caused by violent action of the Brachialis anticus muscle. The amount of displacement varies according to the extent of the fracture. If the tip of the process only is broken off, the fragment is draAvn upAvards by the Brachialis anticus on a level with the coronoid depression of the humerus, and the poAver of flexion is partially lost. If the process is broken off near its root, the fragment is still displaced by the same muscle; at the same time, on extending the forearm, partial dislocation backAvards of the ulna occurs from the action of the Triceps muscle. The appropriate treatment Avould be to relax the Brachialis anticus by flexing the forearm, and to retain the fragments in immediate apposition by keeping the arm in this position. Union is generally liga- mentous. Fracture of the olecranon process (Fig. 165) is a more frequent accident, and is en used either by violent action of the Triceps muscle, or by a fall or Woav upon the point of the elbow. The detached fragment is displaced upAvards, by the action of the Triceps muscle, from half an inch to tAVO inches ; the prominence of the FiS- 165 —Fracture of the Olecranon. elboAv is consequently lost, and a deep holloAV is felt at the back part of the joint, Avhich is much increased on flexing the limb. The patient at the same time loses the poAver of extend- ing the forearm. The treatment con- sists in relaxing the Triceps by ex- tending the forearm, and retaining it in this position by means of a long straight splint applied to the front of the arm; the fragments are thus brought into closer apposition, and may be further approximated by draAv- ing doAvn the upper fragment. Union is generally ligamentous. Fracture of the neck of the radius is an exceedingly rare accident, and is generally caused by direct violence. Its diagnosis is somewhat obscure, on account of the slight deformity visible from the large number of muscles Avhich surround it; but the movements of pronation and supination are entirely lost. The upper fragment is draAvn outwards by the Supi- nator brevis, its extent of displacement being limited by the attachment of the orbicular ligament. The lower fragment is drawn forAvards and slightly upwards by the Biceps, and inwards by the Pronator radii teres, its displacement forwards and upAvards being counteracted in some degree by the Supinator brevis. The treatment essentially consists in relaxing the Biceps, Supinator brevis, and Pro- nator radii teres muscles; by flexing the forearm, and placing it in a position midway betAveen pronation and supination, extension having been previously made so as to bring the parts in apposition. Fracture of the radius (Fig. 166) is more common than fracture of the ulna, on 272 SURGICAL ANATOMY. account of the connection of the former with the wrist. Fracture of the shaft of the radius near its centre may occur from direct violence, but more frequently from a fall forwards, the entire weight of the body being received on the wrist and hand. The upper fragment is Fig. 166.-Fractureofthe Shaft of the Radius. drawn upwards by the Bicepgj and inwards by the Pronator radii teres, holding a position midway betAveen pronation and supination, and a de- gree of fulness in the upper half of the forearm is thus produced; the lower fragment is draAvn downAvards and inwards towards the ulna by the Pronator quadratus, and thrown into a state of pronation by the same muscle; at the same time, the Supinator longus, by elevating the styloid process, into which it is inserted, will serve to depress still more the upper end of the loAver fragment towards the ulna. In order to relax the opposing muscles the forearm should be bent, and the limb placed in a position midway betAveen pro- nation and supination ; the fracture is then easily reduced by extension from the wrist and elbow: Avell-padded splints should then be applied on both sides of the forearm from the elbow to the Avrist; the hand being alloAved to fall, will, by its own weight, counteract the action of the Pronator quadratus and Supinator longus, and elevate this fragment to the level of the upper one. Fracture of the shaft of the ulna is not a common accident; it is usually caused by direct violence. Its more protected position on the inner side of the limb, the greater strength of the shaft, and its indirect connection with the wrist, render it less liable to injury than the radius. It usually occurs a little below the centre, which is the weakest part of the bone. The upper fragment retains its usual position ; but the lower fragment is draAvn outAvards towards the radius by the Pronator quadratus, producing a well-marked depression at the seat of fracture, and some fulness on the dorsal and palmar surfaces of the forearm. The fracture is easily reduced by extension from the wrist and forearm. The forearm should be flexed, and placed in a position midway between pronation and supination, and well-padded splints applied from the elbow to the ends of the fingers. Fracture of the shafts of the radius and ulna together is not a common acci- dent ; it may arise from a direct blow, or from indirect violence. The lower fragments are drawn upwards, sometimes forAvards, sometimes backAvards, according to the direction of the fracture, by the combined actions of the Flexor and Ex- tensor muscles, producing a degree of fulness on the dorsal or palmar surface of the forearm; at the same time the two fragments are drawn into contact by the Pronator quadratus, the radius in a state of pronation : the upper fragment of the radius is draAvn upwards and inAvards by the Biceps and Pronator radii teres to a higher level than the ulna; the upper portion of the ulna is slightly elevated by the Brachialis anticus. The fracture may be reduced by extension from the wrist and elboAv, and the forearm should be placed in the same position as in fracture of the ulna. In the treatment of all cases of fracture of the bones of the forearm, the greatest care is requisite to prevent the ends of the bones from being drawn inwards towards the interosseous space; if this is not carefully attended to, the radius and ulna may become anchylosed, and the movements of pronation and supination entirely lost. To obviate this, the splints applied to the limb should be well padded, so as to press the muscles down into their normal situation in the inter- osseous space, and so prevent the approximation of the fragments. Fracture of the lower end of the radius (Fig. 167) is usually called Colless frac- ture, from the name of the eminent Dublin surgeon who first accurately described it. It usually arises from the patient falling from a height, and alighting upon the hand, Avhich receives the entire weight of the body. This fracture usually OF THE MUSCLES OF THE LOWER EXTREMITY. 273 takes place from half an inch to an inch above the articular surface if it occurs in the adult; but in the child, before the age of sixteen, it is more frequently a sepa- ration of the epiphysis from the diaphysis. The displacement which is produced is very considerable, and bears some resemblance to dislocation of the carpus back- wards, from which it should be carefully distinguished. The lower fragment is drawn upAvards and backAvards behind the upper fragment by the combined actions Fig 167.—Fracture of the Lower End of the Radius. of the Supinator longus and the flexors and extensors of the thumb and carpus, producing a Avell-marked prominence on the back of the wrist, with a deep de- pression behind. The upper fragment projects forAvards, often lacerating the substance of the Pronator quadratus, and is drawn by this muscle into close con- tact with the loAver end of the ulna, causing a projection on the anterior surface of the forearm, immediately above the carpus, from the flexor tendons being thrust forAvards. This fracture may be distinguished from dislocation by the deformity being removed on making sufficient extension, when crepitus may be occasionally detected ; at the same time, on extension being discontinued, the parts immediately resume their deformed appearance. The age of the patient will also assist in determining whether the injury is fracture or separation of the epiphysis. The treatment consists in flexing the forearm, and making powerful extension from the wrist and elbow, depressing at the same time the radial side of the hand, and retaining the parts in this position by well-padded pistol-shaped splints. MUSCLES AND FASCIA OF THE LOWER EXTREMITY. The Muscles of the Lower Extremity are subdivided into groups, corresponding with the different regions of the limb. Pectineus. Iliac Region. Psoas magnus. Psoas parvus. Iliacus. Thigh. Anterior Femoral Region Tensor vaginae femoris. Snrtorius. Rectus. Vastus externus. Vastus internus. Crurseus. Subcrurseus. Internal Femoral Region. Gracilis Adductor longus. Adductor brevis. Adductor magnus. Hip. Gluteal Region. Glutaeus maximus. Glutaeus medius. Glutaeus minimus. Pyriformis. Gemellus superior. Obturator internus. Gemellus inferior. Obturator externus. Quadratus femoris. 20 271 MUSCLES AND FASCIAE. Posterior Femoral Region. Biceps. Semitendinosus. Semimembranosus. Leg. Anterior Tibio-fibular Region. Tibialis anticus. Extensor longus digitorum. Extensor proprius pollicis. Peroneus tertius. Posterior Tibio-fibular Region. Superficial Layer. Gastrocnemius. Plantaris. Soleus. Deep Layer. Popliteus. Flexor longus pollicis. Flexor longus digitorum. Tibialis posticus. Fibular Region. Peroneus longus. Peroneus brevis. Foot. Dorsal Region. Extensor brevis digitorum. Interossei dorsales. Plantar Region. First Layer. Abductor pollicis. Flexor brevis digitorum. Abductor minimi digiti. Second Layer. Musculus accessorius. Lumbricales. Third Layer. Flexor brevis pollicis. Adductor pollicis. Flexor brevis minimi digiti. Transversus pedis. Fourth Layer. Interossei plantares. Iliac Region. Psoas magnus. Psoas parvus. Iliacus.. Dissection. No detailed description is required for the dissection of these muscles. They are exposed after the removal of the viscera from the abdomen, covered by the Peri- toneum and a thin layer of fascia, the fascia iliaca. The Iliac fascia is the aponeurotic layer which lines the back part of the abdominal cavity, and incloses the Psoas and Iliacus muscles throughout their whole extent. It is thin above, and becomes gradually thicker below, as it approaches the femoral arch. The portion investing the Psoas is attached, above, to the ligamentum arcuatum internum ; internally, to the sacrum ; and by a series of arched processes to the intervertebral substances, and prominent margins of the bodies of the vertebrse; the intervals left opposite the constricted portions of the bodies transmitting the lumbar arteries and sympathetic filaments of nerves. Externally, it is continuous with the fascia lumborum. The portion investing the Iliacus is connected, externally, to the Avhole length of the inner border of the crest of the ilium ; internally, to the brim of the true pelvis, where it is continuous with the periosteum, and receives the tendon of insertion of the Psoas parvus. External to the femoral vessels, this fascia is intimately connected with Poupart's ligament, and is continuous with the fascia transversalis; but corresponding to the point where the femoral vessels pass down into the thigh it is prolonged down behind them, forming the posterior wall of the femoral sheath. Below this point, the iliac fascia surrounds the Psoas and' Iliacus muscles to their termination, and becomes continuous with the iliac portion of the fascia lata Internal to the femoral vessels the iliac fascia is connected to the ilio- pectmeal line, and is continuous with the pubic portion of the fascia lata. The iliac vessels he m front of the iliac fascia, but all the branches of the lumbar plexus behind it; it is separated from the peritoneum by a quantity of loose areolar tissue. _ In abscesses accompanying caries of the lower part of the spine, the matter makes its way to the femoral arch, distending the sheath of the Psoas; and when it accumulates in considerable quantity, this muscle becomes absorbed, and the ILIAC REGION. 275 neiwous cords contained in it are dissected out, and lie exposed in the cavity of the abscess ; the femoral vessels, however, remain intact, and the peritoneum seldom becomes implicated, notAvithstanding the extreme thinness of this membrane. RemoAre this fascia, and the muscles of the iliac region will be exposed. The Psoas Magnus is a long fusiform muscle, placed on the side of the lumbar region of the spine and margin of the pelvis (Fig. 16'.'). It arises from the sides of the bodies, from the corresponding intervertebral substances, and from the anterior part of the bases of the transverse processes of the last dorsal and all the lumbar vertebrae. The muscle is connected to the bodies of the vertebrae by five slips, each of Avhich is attached to the upper and lower margins of tAvo vertebrae, and to the intervertebral substance between them; the slips themselves being connected by tendinous arches extending across the constricted part of the bodies, beneath Avhich pass the lumbar arteries and sympathetic nervous filaments. These tendinous arches also give origin to muscular fibres and protect the bloodvessels and nerves from pressure during the action of the muscle. The first slip is attached to the contiguous margins of the last dorsal and first lumbar vertebrae; the last, to the contiguous margins of the fourth and fifth lumbar, and intervertebral substance. From these points, the muscle passes down across the brim of the pelvis, and dimi- nishing gradually in size, passes beneath Poupart's ligament, and terminates in a tendon, which, after receiving the fibres of the Iliacus, is inserted into the lesser trochanter of the femur. Relations. In the lumbar region. By its anterior surface, which is placed behind the peritoneum, Avith the ligamentum arcuatum internum, the kidney, Psoas parvus, renal vessels, ureter, spermatic vessels, genito-crural nerve, the colon, and, along its pelvic border, Avith the common and external iliac artery and vein. By its posterior surface, Avith the transverse processes of the lumbar vertebrae and the quadratus lumborum, from which it is separated by the anterior lamella of the apo- neurosis of the Transversalis; the anterior crural nerve is at first situated in the substance of the muscle, and emerges from its outer border at its loAver part. The lumbar plexus is situated in the posterior part of the substance of the muscle. By its inner side, Avith the bodies of the lumbar vertebrae, the lumbar arteries, the SAnnpathetic ganglia, and its communicating branches with the spinal nerves. In the thigh. It is in relation, in front, with the fascia lata; behind, Avith the capsular ligament of the hip, from Avhich it is separated by a synovial bursa, which some- times communicates Avith the cavity of the joint through an opening of variable size. Bv its inner border, Avith the Pectineus and the femoral artery, which slightly overlaps it. By its outer border, Avith the crural nerve and Iliacus muscle. The Psoas Parvus is a long, slender muscle, placed immediately in front of the preceding. It arises from the sides of the bodies of the last dorsal and first lum- bar vertebnc, and from the intervertebral substance between them. It forms a small, flat, muscular bundle, Avhich terminates in a broad, flattened tendon, which is inserted into the ilio-pectineal eminence, being continuous, by its outer border, with the iliac fascia. This muscle is most frequently found Avanting, being pre- sent, according to M. Theile, in one out of every twenty subjects examined. Relations. It is covered by the peritoneum, and at its origin by the ligamentum arcuatum internum; it rests on the Psoas magnus. The Jliacus is a flat radiated muscle, which fills up the whole of the internal iliac fossa. It arises from the inner concave surface of the ilium, from the inner margin of the crest of that bone; behind, from the ilio-lumbar ligament, and base of the sacrum; in front, from the anterior superior and anterior inferior spinous processes of the ilium, the notch betAveen them, and by a fenv fibres from the cap- sular ligament of the hip joint. The fibres converge to be inserted into the outer side of the tendon common to this muscle and the Psoas magnus, some of them being prolonged doAvn into the oblique line Avhich extends from the lesser trochanter to the linea aspera. Relations. Within the jwlvis: by its anterior surface, Avith the iliac fascia, 276 MUSCLES AND FASCRE. which separates this muscle from the peritoneum, and with the external cutaneous nerve; on the right side, with the caecum; on the left side, with the sigmoid flexure of the colon. By its posterior surface, with the iliac fossa. By its inner border Avith the Psoas magnus, and anterior crural nerve. In the thigh; it is in relation by its anterior surface, Avith the fascia lata, Rectus and Sartorius; behind Avith the capsule of the hip joint, a synovial bursa common to it and the Psoas man*nus being interposed. Nerves. The Psoae muscles are supplied by the anterior branches of the lumbar nerves. The Iliacus from the anterior crural. Actions. The Psoas and Iliacus muscles, acting from above, flex the thigh upon the pelvis, and, at the same time, rotate the femur outAvards, from the obliquity of their insertion into the inner and back part of that bone. Acting from below the femur being fixed, the muscles of both sides bend the lumbar portion of the spine and pelvis forwards. They also serve to maintain the erect position, by supporting the spine and pelvis upon the femur, and assist in raising the trunk when the body is in the recumbent posture. The Psoas parvus is a tensor of the iliac fascia. Anterior Femoral Region. Tensor Vaginae Femoris. Sartorius. Rectus. Fig. 168.—Dissection of Lower Extremity. Front View. / . Dissection of femoral hernia, Scarpa's triangle FRONT vf THICH °f If- . DORSUM*/ TOOT Vastus Externus. Arastus Internus. Cruraeus. Subcrurseus. Dissection. To expose the muscles and fasciae in this region, an incision should be made along Poupart's ligament, from the spine of the ilium to the pubes; from the centre of this, a vertical incision must be carried along the middle line of the thigh to below the knee joint, and connected with the transverse in- cision, carried from the inner to the outer side of the leg. The flaps of integument having been removed the superficial and deep fasciae should be examined. The more advanced stu- dent would commence the study of this region by an examination of the anatomy of femoral hernia, and Scarpa's triangle, the incisions for the dissection of which are marked out in the accompanying figure. Fasci.e of the Thigh. The Suju'ificial fascia forms a con- tinuous layer over the Avhole of the lower extremity, consisting of areolar tis- sue, containing in its meshes much adipose matter, and capable of being separated into two or more layers, betAveen Avhich are found the superficial vessels and nerves. It varies in thickness in differ- ent parts of the limb; in the sole of the foot it is so thin, as to be scarcely demon- strable, the integument being closely ad- herent to the deep fascia beneath, but in the groin it is thicker, and the tAvo layers are separated from one another by the superficial inguinal glands, the internal saphenous vein, and several smaller ves- sels. Of these tAvo layers, the most ANTERIOR FEMORAL REGION. superficial is continuous above with the superficial fascia of the abdomen, the deep layer becoming blended with the fascia lata, a little below Poupart's ligament. The deep layer of superficial fascia is inti- mately adherent to the margins of the saphe- nous opening in the fascia lata, and pierced in this situation by numerous small blood and lymphatic vessels; hence the name crib- riform fascia, which has been applied to it. Subcutaneous bursas are found in the superficial fascia over the patella, point of the heel, and phalangeal articulations of the toes. The Deep fascia of the thigh is exposed on the removal of the superficial fascia, and is named, from its great extent, the fascia lata; it forms a uniform investment for the whole of this region of the limb, but varies in thickness in different part ; thus, it is thickest in the upper and outer side of the thigh, Avhere it receives a fibrinous expansion from the Glutaeus maximus muscle, and the Tensor vaginas femoris is inserted betAveen its layers; it is very thin behind, and at the upper and inner side, Avhere it covers the Adductor muscles, and again becomes stronger around the knee, receiving fibrous expansions from the tendons of the Biceps externally, and from the Sartorius, Gracilis, Semitendinosus, and Triceps extensor cruris in front. The fascia lata is attached, above, to Poupart's ligament and crest of the ilium, behind, to the margin of the sacrum and coccyx, internally to the pubic arch and pec- tineal line, and beloAv to all the prominent points around the knee joint, the condyles of the femur, tuberosities of the tibia, and head of the fibula. That portion which inA'ests the Glutaeus medius (the Gluteal aponeurosis) is very thick and strong, and gives origin, by its inner surface, to some of the fibres of that muscle ; at the upper bor- der of the Glutaeus maximus, it divides into tAvo layers ; the most superficial, very thin, covers the surface of the Glutaeus maximus, and is continuous beloAv Avith the fascia lata; the deep layer is thick aboAre, and blends with the great sacro-sciatic ligament, thin beloAv, Avhere it separates the Glutaeus maxi- mus from the deeper muscles. From the inner surface of the fascia lata, are given off tAvo strong intermuscular septa, which are attached to the whole length of the linea aspera; the external and stronger one ex- tending from the insertion of the Glutasus maximus, to the outer condyle, separates Fig. 169.—Muscles of Femoral Iliac and Anterior ;ions. h a-k •/li $ 27S MUSCLES AND FASCRE. the Vastus externus in front from the short head of the Biceps behind, and gives partial origin to these muscles ; the inner one, the thinner of the tAvo, separates the Vastus internus from the Adductor muscles. Besides these, there are nume- rous smaller septa, separating the individual muscles, and inclosing each in a dis- tinct sheath. At the upper and inner part of the thigh, a little beloAv Poupart's ligament, a large oval-shaped aperture is observed in this fascia; it transmits the internal saphenous vein, and other smaller A'essels, and is termed the saphenous opening. In order more correctly to consider the mode of formation of this aper- ture, the fascia lata is described as consisting, in this part of the thigh, of tyvo por- tions, an iliac portion, and a pubic portion. The iliac portion is all that part of the fascia lata placed on the outer side of the saphenous opening. It is attached, externally, to the crest of the ilium, and its anterior superior spine, to the Avhole length of Poupart's ligament, as far inter- nally as the spine of the pubes, and to the pectineal line in conjunction with Gim- bernat's ligament. From the spine of the pubes, it is reflected downwards and outwards, forming an arched margin, the superior cornu, or outer boundary of the saphenous opening: this margin overlies and is adherent to the anterior layer of the sheath of the femoral vessels; to its edge is attached the cribriform fascia, and, below, it is continuous with the pubic portion of the fascia lata. The pubic portion is situated at the inner side of the saphenous opening; at the loAver margin of this aperture it is continuous with the iliac portion; traced upwards, it is seen to cover the surface of the Pectineus muscle, and passing behind the sheath of the femoral vessels, to which it is closely united, is continu- ous with the sheath of the Psoas and Iliacus muscles, and is finally lost in the fibrous capsule of the hip joint. This fascia is attached above to the pectineal line in front of the insertion of the aponeurosis of the External oblique, and internally, to the margin of the pubic arch. From this description it may be observed, that the iliac portion of the fascia lata passes in front of the femoral vessels, the pubic portion behind them; an apparent aperture consequently exists, betAveen the two, through which the internal saphena joins the femoral vein. The fascia should now be removed from the surface of the muscles. This may be effected by pinching it up between the forceps, dividing it, and separating it from each muscle in the course of its fibres. The Tensor Vagina Femoris is a short, flat muscle, situated at the upper and outer side of the thigh. It arises by aponeurotic fibres from the anterior part of the outer lip of the crest of the ilium, and from the outer surface of the an- terior superior spinous process, between the Glutaeus medius, and Sartorius. The muscle passes obliquely downwards, and a little backwards, to be inserted by tendinous fibres between the two layers of the fascia lata, about one-fourth down the thigh. Relations. By its superficial surface, with a layer of the fascia lata, and the integument. By its deep surface, with the deep" layer of the fascia lata, the Glutaeus medius. Rectus femoris, and Vastus externus. By its anterior border, with the Sartorius, from which it is separated below by a triangular space, in which is seen the Rectus femoris. By its posterior border, with the Glutaeus me- dius, being separated from it below by a slight interval. The Sartorius, the longest muscle in the body, is a flat, narrow, ribbon-like muscle, which arises by tendinous fibres from the anterior superior spinous process of the ilium and upper half of the notch below it; it passes obliquely inwards, across the upper and anterior part of the thigh, then descends vertically, as far as the inner side of the knee, passing behind the inner condyle of the femur, and terminates in a tendon, which, curving obliquely forwards, expands into a broad aponeurosis, which is inserted into the upper part of the inner surface of the shaft of the tibia, nearly as far forwards as the crest. This expansion covers in the insertion of the tendons of the Gracilis and Semitendiiiosus, with which it is partially united, a synovial bursa being interposed between them. An offset ANTERIOR FEMORAL REGION. 279 is derived from this aponeurosis, Avhich blends with the fibrous capsule of the knee joint, and another, given off from its loAver border, blends with the fascia on the inner side of the leg. The relations of this muscle to the femoral artery should be carefully examined, as its inner border forms the chief guide in the operation of including this vessel in a ligature. In the upper third of the thigh, it forms, with the Adductor longus, the sides of a triangular space, Scarpa's triangle, the base of which, turned upwards, is formed by Poupart's ligament; the femoral artery passes perpendicularly through the centre of this space from its base to its apex. In the middle third of the thigh, the femoral artery lies first along the inner bor- der, and then beneath the Sartorius. Relations. By its superficial surface, Avith the fascia lata and integument. Bv its deep surface with the Iliacus, Psoas, Rectus, Vastus internus, sheath of the femoral vessels, Adductor longus, Adductor magnus, Gracilis, long saphenous nerve, and internal lateral ligament of the knee joint. The Quadriceps Extensor Cruris includes the four remaining muscles on the anterior part of the thigh. They are the great Extensor muscles of the leg, forming a large fleshy mass, Avhich covers the anterior surface and sides of the femur, being united beloAV into a single tendon, attached to the tibia, and, above, subdividing into separate portions, which have received separate names. Of these, one occupying the middle of the thigh, connected above Avith the ilium, is called the Rectus Femoris, from its straight course. The other divisions lie in immediate connection Avith the shaft of the femur, which they cover from the condyles to the trochanters, the portion on the outer side of the femur being termed the Vastus Externus, that covering the inner side the Vastus Internus, and that covering the front of the bone, the Cruraus. The two latter portions are, however, so intimately blended, as to form but one muscle. The Rectus Femoris is situated in the middle of the anterior region of the thio*h; it is fusiform in shape, and its fibres are arranged in a bipenniform man- ner. It arises by tAvo tendons; one, the straight tendon, from the anterior inferior spinous process of the ilium, the other is flattened and curves outAvards, to be attached to a groove above the brim of the acetabulum; this is the reflected tendon of the Rectus, it unites with the straight tendon at an acute angle, and then spreads into an aponeurosis, from which the muscular fibres arise. The muscle terminates in a broad and thick aponeurosis, which occupies the loAver two-thirds of its posterior surface, and gradually becoming narrowed into a flattened tendon, is inserted into the patella in common with the Vasti and Crurseus. Relations. By its superficial surface, with the anterior fibres of the Glutaeus medius, the Tensor vaginae femoris, Sartorius, and the Psoas and Iliacus; by its lower three-fourths Avith the fascia lata. By its posterior surface, with the hip joint, the anterior circumflex vessels, and the Crurseus and Vasti muscles. The three remaining muscles have been described collectively by some anatomists, separate from the Rectus, under the name of the Triceps Extensor Cruris ; in order to expose them, divide the Sartorius and Rectus muscles across the middle, and turn them aside, when the Triceps extensor will be fully brought into vieAv. The Vastus Externus is the largest part of the Quadriceps extensor. It arises by a broad aponeurosis, which is attached to the anterior border of the great trochanter, to a horizontal ridge on its outer surface, to a rough line leading from the trochanter major to the linea aspera, and to the Avhole length of the outer lip of the linea aspera; this aponeurosis covers the upper three-fourths of the muscle, and, from its inner surface, many fibres arise. A feAV additional fibres arise from the tendon of the Glutaeus maximus, and from the external inter- muscular septum betAveen the Vastus externus and short head of the Biceps. These fibres form a large fleshy mass, which is attached to a strong aponeurosis, placed on the under surface of the muscle at its loAvest part; this becomes con- 280 MUSCLES AND FASCIA. tracted and thickened into a flat tendon, which is inserted into the outer part of the upper border of the patella, blending with the great Extensor tendon. Relations. By its superficial surface, with the Rectus, the Tensor vaginre femoris, the fascia lata, and the Glutasus maximus, from which it is separated bv a synovial bursa. By its deep surface, with the Crurasus, some large branches of the external circumflex artery being interposed. The Vastus Internus and Cruraus are so inseparably connected together, as to form but one muscle. It is the smallest portion of the Quadriceps extensor • the anterior portion covered by the Rectus being called the Crurasus, the internal portion, which lies immediately beneath the fascia lata, the Vastus Internus. It arises by an aponeurosis, which is attached to the loAver part of the line that extends from the inner side of the neck of the femur to the linea aspera, from the whole length of the inner lip of the linea aspera, and internal intermuscular, septum. It also arises from nearly the Avhole of the internal, anterior, and external surfaces of the shaft of the femur, limited above by the line betAveen the two trochanters, and extending below to Avithin the lower fourth of the bone. From these different origins, the fibres converge to a broad aponeurosis, which covers the anterior surface of the middle portion of the muscle (the Crurasus), and the deep surface of the inner division of the muscle (the Vastus internus), becoming joined and gradually narrowing, it is inserted into the patella. blending with the other portions of the Quadriceps extensor. Relations. By their superficial surface, with the Psoas and Iliacus, the Rectus, Sartorius, Pectineus, Adductors, and fascia lata, femoral artery, vein, and saphe- nous nerve. By its deep surface, with the femur, Subcruraeus, and synovial membrane of the knee joint. Tim student will observe the striking analogy that exists between the Quadriceps extensor and the Triceps brachialis in the upper extremity. So close is this similarity, that M. Cruveilhier has described it under the name of the Triceps femoralis. Like the Triceps brachialis it consists of three distinct divisions or heads ; a middle or long head, analogous to the long head of the Triceps, and of two other portions, which have respectively received the names of the external and internal heads of the muscle. These, it will be noticed, are strictly analogous to the outer and inner heads of the Triceps brachialis. The Subcruraus is a small muscular fasciculus usually distinct from the super- ficial muscle, which arises from the anterior surface of the lower part of the shaft of the femur, and is inserted into the upper part of the synovial pouch that extends upwards from the knee joint behind the patella. This fasciculus is occasionally united with the Crurasus. It sometimes consists of two separate muscular bundles. The tendons of the different portions of the Quadriceps extensor unite at the lower part of the thigh, so as to form a single strong tendon, Avhich is inserted into the upper part of the patella. More properly speaking the patella may he regarded as a sesamoid bone, developed in the tendon of the^Quadriceps extensor, and the ligamentum patellae, which is continued from the lower part of the patella to the tuberosity of the tibia, as the proper tendon of insertion of this muscle. A small synovial bursa is interposed between the tendon and the upper part of the tuberosity Irom the tendons corresponding to the Vasti, a fibrous prolongation is derived, which is attached below to the upper extremities of the tibia and fabula. It serves to protect the knee joint, which is strengthened on its outer side by the fascia lata. Nerves. The Tensor vaginae femoris is supplied by the superior gluteal nerve; the other muscles of this region, by branches from the anterior Actions. The Tensor vaginas femoris is a tensor of the fascia lata; continuing its action, the oblique direction of its fibres enables it to rotate the tliio-b inwards. INTERNAL FEMORAL REGION. 281 In the erect posture, acting from below, it the head of the femur. The Sartorius flexe tinuing to act, the thigh upon the pelvis, inwards, so as to cross one leg over the other. Taking its fixed point from the leg, it flexes the pelvis upon the thigh, and, if one muscle acts, assists in rotating it. The Quadriceps extensor extends the leg upon the thigh. Taking their fixed point from the leg, as in standing, the Extensor muscles Avill act upon the femur, supporting it perpendi- cularly upon the head of the tibia, thus maintaining the entire Aveight of the body. The Rectus muscle assists the Psoas and Iliacus, in supporting the pel- vis and trunk upon the femur, or in bending it forAvards. Internal Femoral Region. Gracilis. Pectineus. Adductor Longus. Adductor Brevis. Adductor Magnus. Dissections. These muscles are at once ox- posed by removing the fascia from the fore- part and inner side of the thigh. The limb should be abducted so as to render the mus- cles tense, and easier of dissection. The Gracilis is the most superficial muscle on the inner side of the thigh. It is a thin, flattened, slender muscle, broad above, narrow and tapering beloAV. It arises by a thin aponeurosis between tAvo and three inches in breadth, from the inner margin of the ramus of the pubes and ischium. The fibres pass vertically doAvnwards and terminate in a rounded tendon Avhich passes behind the internal condyle of the femur, and curving around the inner tuberosity of the tibia, becomes flattened, and is inserted into the upper part of the inner surface of the shaft of the tibia, beneath the tuberosity. The ten- don of this muscle is situated immediately aboA'e that of the Semitendinosus, and beneath the aponeurosis of the Sar- torius, to Avhich it is in part blended. As it passes across the internal lateral ligament of the knee joint, it is separated from it by a synovial bursa, common to it and the Semitendinosus muscle. Relations. By its sujwrficial surface, with the fascia lata and the Sartorius will serve to steady the pelvis upon 5 the leg upon the thigh, and, con- it the same time drawing the limb Fig. 170.—Muscles of the Internal Femoral Region. 2S2 MUSCLES AND FASCRE. below; the internal saphena vein crosses it obliquely near its loAver part, lyin«r superficial to the fascia lata. By its deep surface, with the three Adductors, and the internal lateral ligament of the knee joint. The Pectineus is a flat quadrangular muscle, situated at the anterior part of the upper and inner aspect of the thigh. It arises from the linea ilio-pectinea, from the surface of bone in front of it, betAveen the pectineal eminence and spine of the pubes, and from a tendinous prolongation of Gimbernat's ligament Avhich is attached to the crest of the pubes, and is continuous Avith the fascia covering the outer surface of the muscles; the fibres pass downAvards, backwards and outAvards, to be inserted into a rough line leading from the trochanter minor to the linea aspera. Relations. By its anterior surface, Avith the pubic portion of the fascia lata, Avhich separates it from the femoral vessels and internal saphena vein. Bv its posterior surface, Avith the hip joint, the Adductor brevis and Obturator externus muscles, the obturator vessels and nerve being interposed. By its outer border with the Psoas, a cellular interval separating them, upon which lies the femoral artery. By its inner border, with the margin of the Adductor longus. The Adductor Longus, the most superficial of the three Adductors, is a flat triangular muscle, lying on the same plane as the Pectineus, Avith Avhich it is often blended above. It arises, by a flat narrow tendon, from the front of the pubes, at the angle of junction of the crest with the symphysis; it soon expands into a broad fleshy belly, which, passing doAvnwards, backAvards, and outAvards, is inserted, by an aponeurosis, into the middle third of the linea aspera, betAveen the Vastus internus and the Adductor magnus. Relations. By its anterior surface, with the fascia lata, and near its insertion, Avith the femoral artery and vein. By its posterior surface, with the Adductor brevis and magnus, the anterior branches of the obturator vessels and nerve, and with the profunda artery and vein near its insertion. By its outer border, with the Pectineus. By its inner border, with the Gracilis. The Pectineus and Adductor longus should noAv be divided near their origin, and turned downwards, when the Adductor brevis and Obturator externus will be exposed. The Adductor Brevis is situated immediately beneath the tAvo preceding muscles. It is somewhat triangular in form, and arises by a narrow origin from the outer surface of the descending ramus of the pubes, between the Gracilis and Obturator externus. Its fibres passing backAvards, outwards, and downAvards, are inserted by an aponeurosis into the upper part of the linea aspera, immediately behind the Pec- tineus and upper part of the Adductor longus. Relations. By its anterior surface, with the Pectineus, Adductor Longus, and anterior branches of the obturator vessels and nerve. By its posterior surface, with the Adductor magnus, and posterior branches of the obturator vessels and nerves. By its outer border, with the Obturator externus, and conjoined tendon of the Psoas and Iliacus. By its inner border, with the Gracilis and Adductor mag- nus. This muscle is pierced, near its insertion, by the middle perforating branch of the profunda artery. The Adductor brevis should now be cut away near its origin and turned outwards, when the entire extent of the Adductor magnus will be exposed. The Adductor Magnus is a large triangular muscle, forming a septum between the muscles on the inner, and those on the posterior aspect of the thigh. It arises by short tendinous fibres from a small part of the descending ramus of the pubes, from the ascending ramus of the ischium, and from the outer margin and under surface of the tuberosity of the ischium. Those fibres which arise from the ramus of the pubes are very short, horizontal in direction, and are inserted into the rough line leading from the great trochanter to the linea aspera, internal to the Gluteus maximus; those from the ramus of the ischium are directed downwards and out- wards with different degrees of obliquity, to be inserted by means of a broad apo- neurosis, into the whole length of the interval between the two lips of the linea INTERNAL FEMORAL REGION. 283 aspera and upper part of the internal bifurcation beloAv. The internal portion of the muscle, consisting principally of those fibres which arise from the tuberosity of the ischium, forms a thick fleshy mass consisting of coarse bundles which descend almost vertically, and terminate about the lower third of the thigh in a rounded tendon, which is inserted into the tuberosity above the inner condyle of the femur, being connected by a fibrous expansion to the line leading upwards from the condyle to the linea aspera. BetAveen these tAvo portions of the muscle, an angular interval is left, almost entirely tendinous in structure, for the passage of the femoral vessels into the popliteal space. The external portion of the muscle is pierced by four apertures, the three superior for the three perforating arteries : the fourth, for the passage of the profunda. This muscle gives off an aponeu- rosis, which passes in front of the femoral vessels, and joins with the Vastus internus. Relations. By its anterior surface, Avith the Pectineus, Adductor brevis, Ad- ductor longus, and the femoral vessels. By its posterior surface, with the great sciatic nerve, the Glutasus maximus, Biceps, Semitendinosus, and Semimembra- nosus. By its superior or shortest border, it lies parallel Avith the Quadratus femoris. By its internal or longest border, with the Gracilis, Sartorius, and fascia lata. By its external or attaciied border, it is inserted into the femur behind the Adductor brevis and Adductor longus, which separate it, in front, from the Vastus internus; and in front of the Glutaeus maximus and short head of the Biceps, which separate it from the Vastus externus. Nerves. All the muscles of this group are supplied by the obturator nerve. The Pectineus receives additional branches from the accessory obturator and ante- rior crural; and the Adductor magnus an additional one from the great sciatic. Actions. The Pectineus and three Adductors adduct the thigh poAverfully; they are especially used in horse exercise, the flanks of the horse being firmly grasped between the knees by the action of these muscles. From their oblique insertion into the linea aspera, they rotate the thigh outAvards, assisting the external Rotators, and when the limb has been adducted, they draAv it inwards, carrying the thigh across that of the opposite side. The Pectineus and Adductor brevis and longus assist the Psoas and Iliacus in flexing the thigh upon the pelvis. In progression, also, all these muscles assist in draAving forAvards the hinder limb. The Gracilis assists the Sartorius in flexing the leg and draAving it inAvards ; it is also an Ad- ductor of the thigh. If the loAver extremities are fixed, these muscles may take their fixed point from beloAV and act upon the pelvis, serving to maintain the body in the erect posture; or, if their action is continued, to flex the pelvis forAvards upon the femur. Gluteal Region. Glutaeus Maximus. Gemellus Superior. Glutasus Medius. » Obturator Internus. Glutaeus Minimus. Gemellus Inferior. Pyriformis. Obturator Externus. Quadratus Femoris. Dissection (Fig. 171). The subject should be turned on its face, a block placed beneath the pelvis to make the buttocks tense, and the limbs allowed to hnng over the end of the table, the foot inverted, and the limb abducted. An incision should be made through the integu- ment along the back part of the crest of the ilium and margin of the sacrum to the tip of the coccyx, from Avhich point a second incision should be carried obliquely downwards and outwards to the outer side of the thigh, four inches below the great trochanter. The por- tion of integument included between these incisions, together with the superficial fascia, should be removed in the direction shown in the figure, when the Glutaeus maximus and the dense fascia covering the Glutasus medius will be exposed. The Glutccus JFaximus, the most superficial muscle in the gluteal region, is a very broad and thick fleshy mass, of a quadrilateral shape, which forms the pro- minence of the nates. Its large size is one of the most characteristic points in 2S1 MUSCLES AND FASCIAE. / . Dissection of GLUTEAL RECrCN BACK of THICIi POPLITEAL SPAC£ / ±¥=1 the muscular system in man, connected as it is with the power he has of main- taining the trunk in an erect posture. In structure it is remarkably coarse, being made up of muscular fasciculi lying parallel with one another, and collected together into large bundles, separated by deep cellular intervals. It arises from the superior curved line of the ilium, and the portion of bone including the crest, immediately behind it; from the posterior surface of the last piece of the sacrum the sides of the coccyx, and posterior surface Fig. 171.—Dissection of Lower Extremity. 0f the great sacro-sciatic and posterior sacro- iliac ligaments. The fibres are directed ob- liquely downAvards and outAvards; those forming the upper and larger portion of the muscle (after converging somewhat) terminate in a thick tendinous lamina, which passes across the great trochanter, and is inserted into the fascia lata coATering the outer side of the thigh, the lower portion of the muscle being inserted into the rough line leading from the great trochanter to the linea aspera, betAveen the Vastus externus and Adductor magnus. Three synovial bursas are usually found se- parating the under surface of this muscle from the eminences which it covers. One of these, of large size, and generally multilocular, sepa- rates it from the great trochanter. A second, often -wanting, is situated on the tuberosity of the ischium. A third, betAveen the tendon of this muscle and the Vastus externus. Relations. By its superficial surface, with a thin fascia, which separates it from cellular membrane, fat, and the integument. By its deep surface, with the ilium, sacrum, coccyx, and great sacro-sciatic ligament, the Glutaeus medius, Pyriformis, Gemelli, Obturator inter- nus, Quadratus femoris, the great sacro-sciatic foramen, the tuberosity of the ischium, great trochanter, the Biceps, Semitendinosus, Semi- 5 . sole of foot membranosus, and Adductor magnus muscles, the gluteal vessels and nerve issuing from the pelvis above the Pyriformis muscle, the ischiatic and internal pudic vessels and nerves below it. Its upper border is thin, and connected with the Glutasus medius by the fascia lata. Its lower border, free and prominent, forms the fold of the nates, and is directed toAvards the perinasum. The Glutaeus maximus should now be divided near its origin by a vertical in- cision parried from its upper to its lower border: a cellular interval will be exposed, sepa- rating it from the Glutaeus medius and External rotator muscles beneath. The upper por- tion of the muscle should be altogether detached, and the lower portion turned outwards; the loose areolar tissue filling up the interspace between the trochanter major and tuberosity ot the ischium being removed, the parts already enumerated as exposed'by the removal of this muscle will be seen. The Glutaus Medius is a broad, thick, radiated muscle, situated on the outer surface of the pelvis Its posterior third is covered by the Glutasus maximus; its anterior two-thirds is covered by a layer of fascia,' which is thick and dense, and separates it from the integument, " It arises from the outer surface of the ilium, between the superior and middle curved lines, and from the outer lip of that portion of the crest which is between them; it also arises from the dense f Dissection. GLUTEAL REGION. 285 fascia covering its outer sur- face. The fibres gradually converge to a strong flattened tendon, which is inserted into the oblique line AAdiich tra- verses the outer surface of the great trochanter. A synovial bursa separates the tendon of this muscle from the surface of the trochanter in front of its insertion. Relations. By its superfi- cial surface, with the Glutasus maximus, Tensor vaginas fe- moris, and deep fascia. By its deep surface with the Glutasus minimus and the glu- teal vessels and nerve. Its anterior border is blended with the Glutasus minimus and Tensor vaginae femoris. Its posterior border lies pa- rallel with the Pyriformis. This muscle should now be divided near its insertion and turned upwards, when the Glu- teus minimus will be exposed. The Glutaus Minimus, the smallest of the three Glutaei, is placed immediately beneath the preceding. It is a fan- shaped muscle, arising from the external surface of the ilium, betAveen the middle and inferior curved lines, and behind, from the margin of the great sacro-sciatic notch ; the fibres converge to the deep surface of a radiated aponeurosis, which, terminat- ing in a tendon, is inserted into an impression on the an- terior border of the great tro- chanter. A synovial bursa is interposed betAveen the ante- rior part of the tendon and the great trochanter. Relations. By its superfi- cial surface, Avith the Glutaeus medius, and the gluteal vessels and nerves. By its deep sur- face, Avith the ilium, the re- flected tendon of the Rectus femoris, and capsular liga- ment of the hip joint. Its anterior margin is blended Fig. 172.—Muscles of the Gluteal and Posterior Femoral Regions. 28G MUSCLES AND FASCRE. with the Glutaeus medius. Its posterior margin is often joined with the tendon of the Pyriformis. The Pyriformis is a flat muscle, pyramidal in shape, lying almost parallel with the lower margin of the Glutaeus minimus. It is situated partly Avithin the pelvis at its posterior part, and partly at the back part of the hip joint. It arises from the anterior surface of the sacrum by three fleshy digitations, attached to the por- tions of bone interposed betAveen the second, third, and fourth anterior sacra] foramina, and also from the grooves leading from them : a few fibres also arise from the margin of the great sacro-sciatic foramen, and from the anterior surface of the great sacro-sciatic ligament. The muscle passes out of the pelvis through the great sacro-sciatic foramen, the upper part of which it fills, and is inserted, by a rounded tendon, into the back part of the upper border of the great trochanter, being generally blended with the tendon of the Obturator internus. Relations. By its anterior surface, within the pelvis, Avith the rectum (espe- cially on the left side), the sacral plexus of nerves, and the internal iliac vessels; external to the pelvis, Avith the os innominatum and capsular ligament of the hip joint. By its posterior surface, within the pelvis, Avith the sacrum : and external to it, with the Glutaeus maximus. By its upper border, with the Glutaeus medius, from which it is separated by the gluteal vessels and nerves. By its lower border, with the Gemellus superior ; the ischiatic vessels and nerves, and the interna] pudic vessels and nerves, passing from the pelvis in the interval between them. Dissection. The next muscle, as well as the origin of the Pyriformis, can only be seen when the pelvis is divided, and the viscera contained in this cavity removed. The Obturator Internus, like the preceding muscle, is situated partly Avithin the cavity of the pelvis, partly at the back of the hip joint, It arises from the inner surface of the anterior and external Avail of the pelvis, being attached to the margin of bone around the inner side of the obturator foramen ; viz., from the descending ramus of the pubes, and the ascending ramus of the ischium ; and, laterally, from the inner surface of the body of the ischium, betAveen the margin of the obturator foramen in front, the great sciatic notch behind, and the brim of the true pelvis above. It also arises from the inner surface of the obturator mem- brane, and from the tendinous arch which protects the obturator vessels and nen'e in passing beneath the subpubic arch. The fibres converge doAvmvards and out- Avards, and terminate in four or five tendinous bands, Avhich are found on its deep surface ; these bands are reflected at a right angle over the inner surface of the tuberosity of the ischium, Avhich is covered with cartilage, grooved for their recep- tion, and lined Avith a synovial bursa. The muscle leaves the pelvis by the lesser sacro-sciatic notch ; and the tendinous bands unite into a single flattened tendon, Avhich passes horizontally outAvards, and, after receiving the attachment of the Gemelli, is inserted into the upper border of the great trochanter in front of the Pyriformis. A synovial bursa, narrow and elongated in form, is usually found betAveen the tendon of this muscle and the capsular ligament of the hip. It occa- sionally communicates with that between the tendon and the tuberosity of the ischium, the tAvo forming a single sac. In order to display the peculiar appearances presented by the tendon of this muscle, it should be divided near its insertion and reflected outwards. Relations. Within the pelvis, this muscle is in relation, by its anterior surface, with the obturator membrane and inner surface of the anterior Avail of the pelvis; by its posterior surface, with the obturator fascia, which separates it from the Levator ani; and it is crossed by the internal pudic vessels and nerve. This sur- face forms the outer boundary of the ischio-rectal fossa. External to the pelvis, it is covered by the great sciatic nerve and Glutaeus maximus, and rests on the back part of the hip joint. The Gemelli are two small muscular fasciculi, accessories to the tendon of the Obturator internus, which is received into a groove between them. They have received the names superior and inferior from the position they occupy. GLUTEAL REGION. 2s; The Gemellus Superior, the smaller of the two, is a fleshy fasciculus, which arises from the external surface of the spine of the ischium, and, passing horizon- tally outwards, becomes blended with the upper part of the tendon of the Obturator internus, and is inserted with it into the superior border of the great trochanter This muscle is sometimes Avantino*. Relations By its superficial surface, with the Glutaeus maximus and the ischiatic vessels and nerves. By its deep surface, with the capsule of the hip joint By its upper border, with the lower margin of the Pyriformis. By its lower border with the tendon of the Obturator internus. The Gemellus Inferior arises from the upper part of the outer border of the tuberosity of the ischium, and, passing horizontally outwards, is blended with the lower part of the tendon of the Obturator internus, and inserted with it into the upper border of the great trochanter. Relations. By its superficial surface, with the Glutasus maximus, and the ischiatic vessels and nerves. By its deep surface, it covers the capsular ligament of the hip joint. By its upper border, with the tendon of the Obturator internus BV Slower border, with the tendon of the Obturator externjas and Quadratus femoris Ihe Quadratus Femoris is a short flat muscle, quadrilateral in shape (hence its name), situated immediately below the Gemellus inferior, and above the upper margin of the Adductor magnus. It arises from the external border of the tuberosity of the ischium, and, proceeding horizontally outwards, is inserted into the upper part of the linea quadrati, on the posterior surface of the trochanter major. A synovial bursa is often found between the under surface of this muscle and the lesser trochanter, which it covers. Relations. By its posterior surface, Avith the Glutaeus maximus and the ischiatic vessels and nerves. By its anterior surface, with the tendon of the Obturator externus and trochanter minor. By its upper border, Avith the Gemellus inferior. Its lower border is separated from the Adductor magnus by the internal circumflex vessels. Dissection. In order to expose the next muscle (the Obturator externus), it is necessary to remove the Psoas, Iliacus, Pectineus, and Adductor brevis and longus muscles, from the front and inner side of the thigh; and the Glutasus maximus and Quadratus femoris, from the back part. Its dissection should consequently be postponed until the muscles of the anterior and internal femoral regions have been examined. The Obturator Externus is a flat, triangular muscle, which covers the outer surface of the anterior wall of the pelvis. It arises from the margin of bone im- mediately around the inner side of the obturator foramen, viz., from the body and ramus of the pubes, and the ramus of the ischium ; it also arises from the inner two-thirds of the outer surface of the obturator membrane, and from the tendinous arch which completes the subpubic canal for the passage of the obturator vessels and nerve. The fibres converging pass outwards, and terminate in a tendon which runs across the back part of the hip joint, and is inserted into the digital fossa of the femur. Relations. By its anterior surface, with the Psoas, Iliacus, Pectineus, Adductor longus, Adductor brevis, and Gracilis ; and more externally, with the neck of the femur and capsule of the hip joint. By its posterior surface, with the obturator membrane and Quadratus femoris. Nerves. The Glutaeus maximus is supplied by the inferior gluteal nerve and a branch from the sacral plexus. The Glutasus medius and minimus, by the superior gluteal. The Pyriformis, Gemelli, Obturator internus, and Quadratus femoris, bv branches from the sacral plexus. And the Obturator externus, by the obturator nerve. Actions. The Glutei muscles, when they take their fixed point from the pelvis, are all abductors of the thigh. The Glutaeus maximus and the posterior fibres of the Glutasus medius, rotate the thigh outwards ; the anterior fibres of the Glutasus medius and the Glutaeus minimus rotate it inwards. The Glutasus maximus serves 288 MUSCLES AND FASCIAE. to extend the femur, and the Glutaeus medius and minimus draAv it forAvards. The Glutaeus maximus is also a tensor of the fascia lata. Taking their fixed point from the femur, the Glutasi muscles act upon the pelvis, supporting it and the whole trunk upon the head of the femur, which is especially obvious in standing on one leg. In order to gain the erect posture after the effort of stooping, these muscles draAv the pelvis backAvards, assisted by the Biceps, Semitendinosus, and Semi- membranosus muscles. The remaining muscles are poAverful rotators of the thigh outwards. In the sitting posture, when the thigh is flexed upon the pelvis, their action as rotators ceases, and they become abductors, with the exception of the Obturator externus, which still rotates the femur outAvards. When the femur is fixed, the Pyriformis and Obturator muscles serve to draw the pelvis forAvards if it has been inclined backwards, and assist in steadying it upon the head of the femur. Posterior Femoral Region. Riceps. Semitendinosus. Semimembranosus. Dissection (Fig. 171). Make a vertical incision along the middle of the thigh, from the lower fold of the natesto about three inches below the back of the knee joint, and there connect it with a transverse incision, carried from the inner to the outer side of the leg. A third inci- sion should then be made transversely at the junction of the middle with the lower third of the thigh. The integument having been removed from the back of the knee in the direc- tion indicated in the figure, and the boundaries and contents of the popliteal space examined, the removal of the integument from the remaining part of the thigh should be continued, when the fascia and muscles of this region will be exposed. The Biceps is a large muscle, of considerable length, situated on the posterior and outer aspect of the thigh. It arises by two distinct portions or heads. One, the long head, from an impression at the upper and back part of the tuberosity of the ischium, by a tendon common to it and the Semitendinosus. The femoral or short head, from the outer lip of the linea aspera, between the Adductor magnus and Vastus externus, extending from two inches below the Glutaeus maximus, to within two inches of the outer condyle; it also arises from the external inter- muscular septum. The fibres of the long head form a fusiform belly, which, passing obliquely downwards and a little outAvards, terminates in an aponeurosis which covers the posterior surface of the muscle, and receives the fibres of the short head; this aponeurosis becomes gradually contracted into a tendon, which is inserted into the outer side of the head of the fibula. At its insertion, the tendon divides into two portions, which embrace the external lateral ligament of the knee joint, a strong prolongation being sent forAvards to the outer tuberosity of the tibia, Avhich gives off an expansion to the fascia of the leg. The tendon of this muscle forms the outer hamstring. Relations. By its superficial surface, with the Glutaeus maximus and fascia lata. By its deep surface, Avith the Semimembranosus, Adductor magnus, and Vastus externus, the great sciatic nerve, popliteal artery and vein, and near its insertion, with the external head of the Gastrocnemius, Plantaris, and superior external articular artery. The Semitendinosus, remarkable for the great length of its tendon, is situated at the posterior and inner aspect of the thigh. It arises from the tuberosity of the ischium by a tendon common to it and the long head of the Biceps; it also arises from an aponeurosis Avhich connects the adjacent surfaces of the two muscles to the extent of about three inches after their origin. It forms a fusiform muscle which, passing downAvards and inAvards, terminates a little beloAV the middle of the thigh in a long round tendon, which lies along the inner side of the popliteal space, curving around the inner tuberosity of the tibia, to be inserted into the upper part of the inner surface of the shaft of this bone, nearly as far forAvards as its anterior border. This tendon lies beneath the expansion of the Sartorius, and below that of the Gracilis, to which it is united. A tendinous intersection is usually observed about the middle of this muscle. Relations. By its superficial surface, Avith the Glutaeus maximus and fascia lata, POSTERIOR FEMORAL REGION. 289 By its deep surface, with the Semimembranosus, Adductor magnus, inner head of the Gastrocnemius, and internal lateral ligament of the knee joint The Semimembranosus, so called from the tendinous expansion'on its anterior and posterior surfaces, is situated at the back part and inner side of the thigh It arises by a thick tendon from the upper and outer part of the tuberosity of the ischium above and to the outer side of the Biceps and Semitendinosus; and is inserted into the posterior part of the inner tuberosity of the tibia, beneath the internal lateral ligament. The tendon of this muscle at its insertion divides into three portions; the middle portion is the fasciculus of insertion into the back part of the inner tuberosity; it sends down an expansion to cover the Popliteus muscle. The internal portion is horizontal, passing forwards beneath the internal lateral ligament, to be inserted into a groove along the inner side of the internal tuberosity. The posterior division passes upwards and backwards, to be inserted into the back part of the outer condyle of the femur, forming the chief part of the posterior ligament of the knee joint. The tendon of origin of this muscle expands into an aponeurosis, which covers the upper part of its anterior surface; from this muscular fibres arise, and con- verge to another aponeurotic expansion, which covers the loAver part of its posterior surface, and this contracts into the tendon of insertion. The tendons of the two preceding muscles, with those of the Gracilis and Sartorius, form the inner ham- string. Relations. By its superficial surface, with the Glutaeus maximus, Semitendi- nosus, Biceps, and fascia lata. By its deep surface, Avith the Quadratus femoris, Adductor magnus, and inner head of the Gastrocnemius. It covers the popliteal artery and vein, and is separated from the knee joint by a synovial membrane. By its inner border, with the Gracilis. By its outer border, with the great sciatic nerve. Nerves. The muscles of this region are supplied with the great sciatic nerve. Actions. _ The three hamstring muscles flex the leg upon the thigh. When the knee is semiflexed, the Biceps, from its oblique direction downwards and outwards, rotates the leg slightly outAvards; and the Semimembranosus, in consequence of its oblique direction, rotates the leg inwards, assisting the Popliteus. Taking their fixed point from beloAV, these muscles serve to support the pelvis upon the head of the femur, and to draw the trunk directly backAvards, as is seen in feats of strength, when the body is throAvn backwards in the form of an arch. Surgical Anatomy. The tendons of these muscles occasionally require subcutaneous divi- sion in some forms of spurious anchylosis of the knee joint, dependent upon permanent con- traction and rigidity of the flexor muscles, or from stiffening of the ligamentous and other tissues surrounding the joint, the result of disease. This is easily effected by putting the tendon upon the stretch, and inserting a narrow sharp-pointed knife between it and the skin; the cutting edge being then turned towards the tendon, it should be divided, taking care that the wound in the skin is not at the same time enlarged. This operation has been attended with considerable success in some cases of stiffened knee from rheumatism, gradual extension being kept up for some time after the operation. Muscles and Fascle of the Leg. Dissection (Fig. 168). _ The knee should be bent, a block placed beneath it, and the foot kept in an extended position; an incision should then be made through the integument in the middle line of the leg to the ankle, and continued alon^ the dorsum of the foot to the toes. A second incision should be made transversely across the ankle, and a third in the same direction across the bases of the toes: the flaps of integument included between these incisions should be removed, and the fascia of the leg examined. The Fascia of the Leg forms a complete investment to the whole of this region of the limb, excepting to the inner surface of the tibia, to which it is unattached. It is continuous above Avith the fascia lata, receiving an expansion from the tendon of the Biceps on the outer side, and from the tendons of the Sartorius, Gracilis, and Semitendinosus on the inner side; in front, it blends with the periosteum covering the tibia and fibula; below, it is continuous with 21 LES AND FASCIA. the annular ligaments of the ankle. It is thick and dense in the upper and anterior part of the leg, and gives attachment, by its inner surface, to the Tibialis anticus and Ex- tensor longus digitorum muscles; but thinner behind, Avhere it covers the Gastrocnemius, and Soleus muscles. Its inner surface gives off, on the outer side of the leg, tAvo strong inter- muscular septa, Avhich inclose the Peronei muscles, and separate them from those on the anterior and posterior tibial regions, and several smaller and more slender processes inclose the individual muscles in each region; at ihe same time, a broad transverse intermus- cular septum intervenes between the superficial and deep muscles in the posterior tibio-fibular region. The fascia should now be removed by dividing it in the same direction as the integument, excepting oppo- site the ankle, where it should be left entire. The removal of the fascia should be commenced from below, opposite the tendons, and detached in the line ot direction of the muscular fibres. Muscles of the Leg. These maybe divided into three groups: those on the anterior, those on the posterior, and those on the outer side. Anterior Tibio-fibular Region. Tibialis Anticus. Extensor Proprius Pollicis. Extensor Longus Digitorum. Peroneus Tertius. The Tibialis Anticus is situated on the outer side of the tibia, being thick and fleshy at its upper part, tendinous beloAv. It arises from the outer tuberosity and upper tAvo-thirds of the external surface of the shaft of the tibia; from the adjoining part of the interosseous membrane; from the deep fascia of the leg; and from the intermuscular septum between it and the Extensor communis digitorum: the fibres pass vertically doAvnwards, and terminate in a tendon, Avhich is apparent on the anterior surface of the muscle at the lower third of the leg. After passing through the innermost compartment of the anterior annular ligament, it is inserted into the inner side of the internal cuneiform bone, and base of the metatarsal bone of the great toe. Relations. By its anterior surface, with the deep fascia, and with the annular ligament. By its posterior surface, Avith the interosseous membrane, tibia, and ankle joint. By its inner surface, with the tibia. By its outer surface, with the Extensor longus digitorum, and ANTERIOR TIBIO-FIBULAR REGION. 291 Extensor proprius pollicis, the anterior tibial vessels and nerve lying between it and the last-mentioned muscles. The Extensor Proj>rius J'oflieis is a thin, elongated, and flattened muscle, situated betAveen the Tibialis anticus and Extensor longus digitorum. It arises from the anterior surface of the fibula for about the tAvo middle fourths of its extent, its origin being internal to the Extensor longus digitorum; it also arises from the interosseous membrane to a similar extent. The fibres pass doAvn- wards, and terminate in a tendon, Avhich occupies the anterior border of the muscle, passes through a distinct compartment in the annular ligament, and is inserted into the base of the last phalanx of the great toe. Opposite the metatarso- phalangeal articulation, the tendon gives off a thin prolongation on each side, which covers its surface. Relations. By its anterior border, Avith the deep fascia of the leg, and the anterior annular ligament. By its posterior border, Avith the interosseous mem- bi'ane, fibula, tibia, ankle joint, and Extensor brevis digitorum. By its outer side, Avith the Extensor longus digitorum above, the dorsalis pedis artery and anterior tibial nerve below. By its inner side, with the Tibialis anticus, and the anterior tibial vessels above. The Extensor Longus Digitorum is an elongated, flattened, semi-penniform muscle, situated the most external of all the muscles on the forepart of the leg. It arises from the outer tuberosity of the tibia, from the upper three-fourths of the anterior surface of the shaft of the fibula, from the interosseous membrane, deep fascia, and from the intermuscular septa between it and the Tibialis anticus on the inner, and the Peronei on the outer side. The fibres pass downAvards, and terminate in four tendons, Avhich pass through a distinct canal in the annular liga- ment, together with the Peroneus tertius, run across the dorsum of the foot, and are inserted into the second and third phalanges of the four lesser toes. The mode in Avhich these tendons are inserted is the folloAving. Each tendon opposite the metatarso-phalangeal articulation is joined on its outer side by a tendon of the Extensor brevis digitorum (except the fourth), and receives a fibrous expansion from the Interossei and Lumbricales; it then spreads into a broad aponeurosis, which covers the dorsal surface of the first phalanx: this aponeurosis, at the articulation of the first Avith the second phalanx, divides into three slips, a middle one, which is inserted into the base of the second phalanx, and tAvo lateral slips, which, after uniting on the dorsal surface of the second phalanx, are continued onAvards to be inserted into the base of the third. llc!ations. By its anterior surface, with the deep fascia of the leg, and the annular ligament. By its posterior surface, with the fibula, interosseous mem- brane, ankle joint, and Extensor brevis digitorum. By its inner side, with the Tibialis* anticus, Extensor proprius pollicis, and anterior tibial vessels and nerve. By its outer side, with the Peroneus longus and brevis. The Peroneus Tertius is but a part of the Extensor longus digitorum, being almost ahvays intimately united Avith it. It arises from the loAver fourth of the anterior surface of the fibula; its outer part, from the lower part of the inter- osseous membrane; and from an intermuscular septum betAveen it and the Pero- neus brevis. Its tendon, after passing through the same canal in the annular ligament as the Extensor longus digitorum, is inserted into the base of the meta- tarsal bone of the little toe on its dorsal surface. This muscle is often Avanting. Nerves. These muscles are supplied by the anterior tibial nerve. Actions. The Tibialis anticus and Peroneus tertius are the direct flexors of the tarsus upon the leg ; the former muscle, from the obliquity in the direction of its tendon, raises the inner border of the foot; and the latter, acting Avith the Peroneus brevis and longus, -will draAv the outer border of the foot upAvards and the sole outAvards. The Extensor longus digitorum and Extensor proprius pollicis extend the phalanges of the toes, and, continuing their action, flex the tarsus upon the leg. Taking their origin from below, in the erect posture, all these muscles 192 MUSCLES AND FASCRE. Fig. 174.—Muscles of the Back of the Leg Superficial Layer. 7 ™ serve to fix the bones of the leg in a perpendicular direction, and give increased strength to the ankle joint. Posterior Tibio-fibular Rkgion. Dissection (Fig. 171). Make a vertical incision along the middle line of the back of the leg, from the lower part of the popliteal space to the heel, connecting it below by a trans- verse incision extending between the two malleoli; the flaps of integument being removed, the fascia and muscles should be examined. The muscles in this region of the leg are subdivided into tAvo layers, superficial and deep. The superficial layer constitutes a poAverful muscular mass, forming Avhat is called the calf of the leg. Their large size is one of the most characteristic features of the muscular apparatus in man, and bears' a direct connection Avith his ordinary attitude and mode of progression. Superficial Layer. Gastrocnemius. Soleus. Plantaris. The Gastrocnemius is the most superficial muscle at the back part of the leg, and forms the greater part of the calf. It arises by tAvo heads, AA'hich are connected to the condyles of the femur by tAvo strong flat tendons. The inner head, the larger, and a little the most posterior, is attached to a depression at the upper and back part of the inner condyle: the outer head, to the upper and back part of the external condyle, immediately above the origin of the Popliteus. Both heads, also, arise by a feAV tendinous and fleshy fibres from the ridges which are continued up- wards from the condyles to the linea aspera. Each tendon spreads into an aponeurosis, which covers the posterior surface of that portion of the muscle to which it belongs; that covering the inner head being longer and thicker than the outer. From the an- terior surfaces of these tendinous expansions muscular fibres are given off; those in the median line, which correspond to the acces- sory portion of the muscle derived from the bifurcations of the linea aspera, unite at an angle upon a median tendinous raphe beloAV. The remaining fibres converge to the poste- rior surface of an aponeurosis Avhich covers. the front of the muscle, and this, gradually contracting, unites Avith the tendon of the Soleus, and forms with it the tendo Achillis. Relations. By its superficial surface, with the fascia of the leg, which sepa- rates it from the external saphenous vein and nerve. By its deep surface, with the //.'/ s RfchttNIUfi LONCUS a t POSTERIOR TIBIO-FIBULAR REGION. 293 posterior ligament of the knee joint, the Popliteus, Soleus, Plantaiis, popliteal vessels, and internal popliteal nerve. The tendon of the inner head corresponds with the back part of the inner condyle, from Avhich it is separated by a synovial bursa, Avhich in some cases communicates Avith the cavity of the knee joint. The tendon of the outer head contains a sesamoid fibro-cartilage (rarely osseous), Avhere it plays over the corresponding outer condyle ; and one is occasionally found in the tendon of the inner head. The Gastrocnemius should be divided across just below its origin, and turned down- wards, in order to expose the next muscles. The Soleus is a broad flat muscle, situated immediately beneath the preceding. It has received its name from the fancied resemblance it bears to a sole-fish. It arises by tendinous fibres from the back part of the head, and from the upper half of the posterior surface of the shaft of the fibula, from the oblique line of the tibia. and from the middle third of its internal border ; some fibres also arise from a tendinous arch Avhich passes betAveen the tibial and fibular origins of the muscle. and beneath Avhich the posterior tibial vessels and nerve pass into the leg. The fibres pass backAvards to an aponeurosis which covers the posterior surface of the muscle, and this, gradually becoming thicker and narrower, joins with the tendon of the Gastrocnemius, and forms with it the tendo Achillis. Relations. By its superficial surface, Avith the Gastrocnemius and Plantaris. By its deep surface, Avith the Flexor longus digitorum, Flexor longus pollicis, Tibialis posticus, and posterior tibial vessels and nerve ; from Avhich it is separated bv the transverse intermuscular septum, interposed betAveen the superficial and deep muscles at the back of the leg. The Tendo Achillis, the common tendon of the Gastrocnemius, Soleus, and Plantaris, is the thickest and strongest tendon in the body. It is about six inches in length, and formed by the junction of the aponeuroses of the two preceding muscles. It commences about the middle of the leg, but receives fleshy fibres much lower on its anterior surface. Gradually becoming contracted beloAV, it is inserted into the loAver part of the posterior tuberosity of the os ealcis, a synovial bursa being interposed betAveen the tendon and the upper part of the tuberosity. Externally it is covered by the fascia and the integument, and it is separated beneath from the deep-seated muscles and vessels, by a considerable interval filled up Avith areolar and adipose tissue. The Plantaris is an extremely diminutive muscle, placed betAveen the Gastroc- nemius and Soleus, and remarkable for the long and delicate tendon which it presents. It arises from the lower part of the external bifurcation of the linea aspera, and from the posterior ligament of the knee joint. It forms a small fusi- form belly, about two inches in length, Avhich terminates in a long and slender tendon, Avhich crosses obliquely between the tAvo muscles of the calf, and, running along the inner border of the'tendo Achillis, is inserted with it into the posterior part of the os ealcis. This muscle is occasionally double ; it is sometimes Ayanting. Occasionally its tendon is lost in the subcutaneous adipose tissue, or in the internal annular ligament. Nerves. These muscles are supplied by the internal popliteal nerve. Actions. The muscles of the calf possess considerable power, and are constantly called into use in standing, walking, dancing, and leaping, hence the large size they usually present. In walking, these muscles draw powerfully upon the os ealcis, raising the heel, and, with it, the entire body from the ground ; the body bcing thus supported on the raised foot, the opposite limb can be carried forwards. In standing, the Soleus, taking its fixed point from below, steadies the leg upon the foot, and prevents the body from falling forwards, to which there is a constant tendency from the superincumbent Aveight. The Gastrocnemius, acting from below, serves to flex the femur upon the tibia, assisted by the Popliteus. The Plantaris is the rudiment of a large muscle which exists in some of the loAver animals and serves as a tensor of the plantar fascia. 291 MUSCLES AND FASCIiE. Fig. 175.—Muscles of the Back of the Leg Deep Layer. / Posterior Tibio-fibular Region. Deep Layer. Popliteus. Flexor Longus digitorum. Flexor Longus Pollicis. Tibialis Posticus. Dissection. Detach the Soleus from its attachment to the fibula and tibia, and turn it downwards, when the deep layer of muscles is exposed, covered by the deep fascia of the leg. The deep fascia of the leg is a broad, transverse intermuscular septum, interposed betAveen the superficial and deep muscles, in the posterior tibio-fibular region. On each side it is connected to the margins of the tibia and fibula. Above, Avhere it covers the Popliteus, it is thick and dense, and receives an expansion from the tendon of the Semimembranosus ; it is thinner in the middle of the leg, but, beloAv, Avhere it covers the tendons passing behind the mal- leoli, it is thickened. It is continued on- wards in the interval betAveen the ankle and the heel, Avhere it covers the vessels and is blended Avith the internal annular liga- ment. This fascia should now be removed, com- mencing from below opposite the tendons, and detaching it from the muscles in the direction of their fibres. The Popliteus is a thin, flat, triangular muscle, which forms the floor of the popli- teal space, and is covered in by a tendinous expansion, derived from the Semimembra- nosus muscle. It arises by a strong flat tendon, about an inch in length, from a deep depression on the outer side of the external condyle of the femur, and from the posterior ligament of the knee joint; and is inserted into the inner two-thirds of the triangular surface above the oblique line on the poste- rior part of the shaft of the tibia, and into the tendinous expansion covering the surface of the muscle. The tendon of this muscle is covered in by that of the Biceps and the external lateral ligament of the knee joint; it grooves the outer surface of the external semilunar cartilage, and is invested by the synovial membrane of the knee joint. Relations. By its superficial surface, with the fascia above mentioned, Avhich separates it from the Gastrocnemius, Plantaris, popli- teal vessels, and internal popliteal nerve. By its deep surface, with the tibio-fibular articulation and back of the tibia. The Flexor Longus Pollicis is situated on the fibular side of the leg, and is the most superficial, and largest of the three next muscles. It arises from the loAver two- POSTERIOR TIBIO-FIBULAR REGION. 295 thirds of the internal surface of the shaft of the fibula, with the exception of an inch below, from the lower part of the interosseous membrane, from an intermus- cular septum between it and the Peroneus longus and brevis, externally ; and from the fascia covering the Tibialis posticus. The fibres pass obliquely downwards and backAvards, and terminate around a tendon which occupies nearly the whole length of the posterior surface of the muscle. This tendon passes through a groove on the posterior surface of the tibia, external to that for the Tibialis pos- ticus and Flexor^ longus digitorum ; it then passes through a second groove on the posterior extremity of the astragalus, and along a third groove, beneath the tubercle of the os ealcis, into the sole of the foot, where it runs forwards betAveen the two heads of the Flexor brevis pollicis, and is inserted into the base of the last pha- lanx of the great toe. The grooves in the astragalus and os ealcis, which contain the tendon of this muscle, are converted by tendinous fibres into distinct canals, lined by synovial membrane ; and as the tendon crosses the sole of the foot, it is connected to the common Flexor by a tendinous slip. Relations. By its superficial surface, with the Soleus, and tendo Achillis, from which it is separated by the deep fascia. By its deep surface, with the fibula, Tibialis posticus, the peroneal vessels, the lower part of the interosseous mem- brane, and the ankle joint. By its outer border, Avith the Peroneus longus and brevis. By its inner border, with the Tibialis posticus and Flexor longus digi- torum. The Flexor Longus Digitorum is situated on the inner or tibial side of the leg. At its origin, it is thin and pointed, but gradually increases in size as it descends. It arises from the posterior surface of the shaft of the tibia, immediately be- Ioav the oblique line, to within three inches of its extremity, internal to the tibial origin of the Tibialis posticus ; some fibres also arise from the intermus- cular septum, betAveen it and the Tibialis posticus. The fibres terminate in a tendon, Avhich runs nearly the Avhole length of the posterior surface of the muscle. This tendon passes behind the inner Malleolus, in a groove, common to it and the Tibialis posticus, from which it is separated by a fibrous septum ; each tendon is lined by a separate synovial membrane. It then passes, obliquely, forAvards and outwards, beneath the arch of the os ealcis, into the sole of the foot, Avhere, crossing beneath the tendon of the Flexor longus pollicis, to which it is connected by. a strong, tendinous slip, it becomes expanded, is joined by the Musculus accessorius, and finally divides into four tendons, which are inserted into the bases of the last phalanges of the four lesser toes, each tendon passing through a fissure in the tendon of the Flexor breAris digitorum, opposite the middle of the first phalanges. Relations. Ln the leg. By its superficial surface, Avith the Soleus, and the posterior tibial Aressels and nerve, from which it is separated by the deep fascia. By its deep surface, Avith the tibia and Tibialis posticus. In the front, it is coArered by the Abductor pollicis, and Flexor brevis digitorum, and crosses beneath the Flexor longus pollicis. The Tibialis Posticus lies between the tAvo preceding muscles, and is the most deeply se'ated of all the muscles in the leg. It commences above, by tAvo pointed processes, separated by an angular interval, through Avhich the anterior tibial vessels pass forAvards to the front of the leg, arising from the posterior surface of the interosseous membrane its whole length, excepting its loAvest part, from the posterior surface of the shaft of the tibia, external to the Flexor longus digitorum, betAveen the commencement of the oblique line above and the centre of the external border of the bone beloAv, and from the upper tAvo-thirds of the inner surface of the shaft of the fibula ; some fibres also arise from the deep fascia, and from the intermuscular septa separating it from the adjacent muscles on each side. The fibres terminate in a tendon, Avhich passes in front of the Flexor longus digitorum, through a groove behind the inner malleolus, inclosed in a separate sheath ; it then passes through another sheath, over the internal lateral ligament, and beneath the calcaneo-scaphoid articulation, and is inserted 296 MUSCLES AND FASCRE. into the tuberosity of the scaphoid, and internal cuneiform bones. The tendon of this muscle contains a sesamoid bone, near its insertion, and gives off fibrous expansions, one of Avhich passes backAvards to the os ealcis, others outAvards to the middle of the external cuneiform, and some forAvards to the bases of the third and fourth metatarsal bones. Relations. By its superficial surface, Avith the Soleus, Flexor longus digito- rum, Flexor longus pollicis, the posterior tibial vessels and nerve, and the pero- neal vessels, from Avhich it is separated by the deep fascia. By its deep surface, with the interosseous ligament, the tibia, fibula, and ankle joint. Nerves. The Popliteus is supplied by the internal popliteal nerve ; the remaining muscle of this group by the posterior tibial nerve. Actions. The Popliteus assists in flexing the leg upon the thigh, and, Avhen flexed, it may rotate the tibia inAvards. The Tibialis posticus is a direct extensor of the tarsus upon the leg ; acting in conjunction Avith the Tibialis anticus, it turns the sole of the foot inwards, antagonizing the Peroneus longus, Avhich turns it outAvards. The Flexor longus digitorum and Flexor longus pollicis are the direct flexors of the phalanges, and, continuing their action, extend the foot upon the leg; they assist the Gastrocnemius and Soleus in extending the foot, as in the act of walking, or in standing on tiptoe. In consequence of the oblique direction of the tendon of the long Extensor, the toes would be draAvn inAvards, Avere it not for the Flexor accessorius muscle, which is inserted into the outer side of that tendon, and draAvs it to the middle line of the foot during its action. Tak- ing their fixed point from the foot, these muscles serve to maintain the upright pos- ture, by steadying the tibia and fibula, perpendicularly, upon the ankle joint. They also serve to raise these bones from the oblique position they assume in the stooping posture. Fibular Region. Peroneus Longus. Peroneus Brevis. Dissection. These muscles are readily exposed, by removing the fascia covering their sur- faces, from below upwards, in the line of direction of their fibres. The Peroneus Longus is situated at the upper part of the outer side of the leg. It arises from the head, and upper two-thirds of the outer surface of the shaft of the fibula, from the deep fascia, and from the intermuscular septa between it and the muscles on the anterior, and those on the posterior surface of the leg. It terminates in a long tendon, which passes behind the outer malleolus, in a groove, common to it and the Peroneus brevis, the groove being converted into a canal by a fibrous band, and the fendons, invested by a com- mon synovial membrane ; it is then reflected, obliquely forwards, across the outer side of the os ealcis, being contained in a separate fibrous sheath, lined by a prolongation of the synovial membrane, from the groove behind the malleolus. Having reached the outer side of the cuboid bone, it runs, in a groove, on its under surface, which is converted into a canal by the long calcaneo-cuboid liga- ment, lined by a synovial membrane, and crossing, obliquely, the sole of the foot, is inserted into the outer side of the base of the metatarsal bone of the great toe. The tendon of the muscle has a double reflection, first, behind the external mal- leolus ; secondly, on the outer side of the cuboid bone; in both of these situations, the tendon is thickened, and, in the latter, a sesamoid bone is usually developed in its substance. Relations. By its superficial surface, with the fascia and integument. By its deep surface, with the fibula, the Peroneus brevis, os ealcis, and cuboid bone. By its anterior border, a tendinous septum intervenes between it and the Extensor longus digitorum. By its posterior border, an intermuscular septum separates it from the Soleus above, and the Flexor longus pollicis below. The Peroneus Brevis lies beneath the Peroneus longus, and is shorter and smaller than it. It_ arises from the lower two-thirds of the external surface of the shaft of the fibula, internal to the Peroneus longus : from the anterior and poste- FIBULAR REGION. 297 rior borders of the bone ; and from the intermuscular septa separating it from the adjacent muscles on the front and back part of the leg. The fibres pass vertically downwards, and terminate in a tendon, Avhich runs through the same groove as the preceding muscle, behind the external malleolus, being contained in the same fibrous sheath, and lubricated by the same synovial membrane ; it then passes through a separate sheath on the outer side of the os ealcis, above that for the tendon of the Peroneus longus, and is finally inserted into the base of the meta- tarsal bone of the little toe, on its dorsal surface. Relations. By its superficial surface, Avith the Peroneus longus and the fascia of the leg and foot. By its deep surface, Avith the fibula and outer side of the os ealcis. Nerves. The Peroneus longus and brevis are supplied by the musculo-cutaneous branch of the external popliteal nerve. Actions. The Peroneus longus and brevis extend the foot upon the leg, in con- junction with the Tibialis posticus, antagonizing the Tibialis anticus and Peroneus tertius, Avhich are flexors of the foot. The Peroneus longus also everts the sole of the foot; hence the extreme eversion observed in fracture of the loAver end of the fibula, Avhere that bone offers no resistance to the action of this muscle. Taking their fixed point below, they serve to steady the leg upon the foot. This is especially the case in standing upon one leg, w here the tendency of the superin- cumbent weight is to throAv the leg inwards; and the Peroneus longus overcomes this by draAving on the outer side of the leg, and thus maintains the perpendicular direction of the limb. Surgical Anatomy. The student should now consider the position of the tendons of the various muscles of the leg, their relation with the ankle joint and surrounding blood- vessels, and especially their action upon the foot, as their rigidity and contraction give rise to one or the other forms of deformity known as club-foot. The most simple and common deformity is the talipes equiuus, the heel being raised from the ground by rigidity and con- traction of the Gastrocnemius muscle, and the patient walking upon the ball of the foot. In the talipes varus, which is the more common congenital form, the heel is raised by the tendo Achillis, the inner border of the foot drawn upwards by the Tibialis anticus, and the anterior two-thirds of the foot twisted inwards by the Tibialis posticus, and Flexor longus digitorum, the patient walking upon the dorsum of the foot and outer ankle. In the talipes valgus, the outer edge of the foot is raised by the Peronei muscles, and the patient walks upon the inner ankle. In the talipes calcaneus, the foot is raised by the extensor muscles, the heel is depressed, and the patient walks upon it. Each of these deformities may be successfully relieved (after other remedies fail) by division of the opposing tendons; by this means the foot regains its normal position, and the tendons heal by the organization of lymph thrown out between the divided ends. The operation is easily performed by putting the contracted tendon upon the stretch, and dividing it by means of a narrow sharp-pointed knife inserted between it and the skin. Muscles and Fascle of the Foot. The fibrous bands which serve to bind down the tendons in front and behind the ankle in their passage to the foot, should now be examined: they are termed the annular liga- ments, and are three in number,—anterior, internal, and external. The Anterior Annular Ligament consists of a superior or vertical portion, which binds down the extensor tendons as they descend on the front of the tibia; and an inferior or horizontal portion, which retains them in connection with the tarsus : the two portions being connected by a thin intervening layer of fascia. The upper and stronger portion is attached, externally, to the lower end of the fibula; internally, to the tibia, and, above, is continuous with the fascia of the leg: it contains two separate sheaths, one internally, for the tendon of the Tibialis anti- cus; one externally, for the tendons of the Extensor longus digitorum and Pero- neus tertius, the tendon of the Extensor proprius pollicis, and the anterior tibial vessels and nerve pass beneath it. The loAver portion is attached externally to the upper surface of the os ealcis, in front of the depression for the interosseous ligament, and internally to the inner malleolus and plantar fascia: it contains three sheaths, the most internal for the tendon of the Tibialis anticus, the next in order for the 298 MUSCLES AND FASCRE. tendon of the Extensor proprius pollicis, and the most external for the Extensor communis digitorum and Peroneus tertius: the anterior tibial vessels and nerve lie altogether beneath it. These sheaths are lined by separate synovial membranes. The Internal Annular Ligament is a strong fibrous band, which extends from the inner malleolus above, to the internal margin of the os ealcis beloAv, converting a series of bony grooves in this situation into osteo-fibrous canals, for the passage of the tendons of the flexor muscles and vessels into the sole of the foot. It is continuous above Avith the deep fascia of the leg, beloAv with the plantar fascia and the fibres of origin of the Abductor pollicis muscle. The three canals which it forms, transmit from Avithin outAvards, first, the tendon of the Tibialis posticus; secondly, the tendon of the Flexor longus digitorum, then the posterior tibial vessels and nerve, which run through a broad space beneath the ligament; lastly, in a canal formed partly by the astragalus, the tendon of the Flexor longus pollicis. Each of these canals is lined by a separate synovial membrane. The External Annular Ligament extends from the extremity of the outer malleolus to the outer surface of the os ealcis, and serves to bind doAvn the tendons of the Peronei muscles in their passage beneath the outer ankle. The two tendons are inclosed in one synovial sac. Dissection of the Sole of the Foot. The foot should be placed on a high block, with the sole uppermost, and firmly secured in that position. Carry an incision around the heel and along the inner and outer borders of the foot to the great and little toes. This incision should divide the integument and thick layer of granular fat beneath, until the fascia is visible; it should then be removed from the fascia in a direction from behind forwards, as seen in Fig. 171. The Plantar Fascia, the densest of all the fibrous membranes, consists of three portions, a middle and two lateral. The middle portion, of great strength and thickness, consists of dense glistening fibres, disposed, for the most part, longitudinally ; it is narrow and thick behind, and attached to the inner tuberosity on the under surface of the os ealcis, behind the origin of the Flexor brevis digitorum, and becoming broader and thinner as it passes fonvards, divides opposite the middle of the metatarsal bones into five fasciculi, one for each of the toes. Each of these fasciculi divides opposite the metatarso-phalangeal articulation into two slips, which embrace the sides of the flexor tendons of the toes, and are inserted into the bases of the metatarsal bones, and into the transverse ligaments of the corresponding articulation, thus forming a series of arches through Avhich the tendons of the short and long flexors pass to the toes. The intervals left between the five primary fasciculi allow of the passage of the digital vessels and nerves, and the tendons of the Lumbricales and Interossei muscles. At the point of division of the fascia into fasciculi and slips, numerous transverse fibres are superadded, which serve to increase the strength of the fascia at this part, by binding the processes together and con- necting them with the integument. The middle portion of the plantar fascia is continuous with the lateral portions at each side, and sends upwards into the foot, at their point of junction, two strong vertical intermuscular septa, broader in front than behind, which separates the middle from the external and internal plantar groups of muscles. From these again thinner transverse septa are derived, which separate the various layers of muscles in this region ; the upper surface of this fascia gives attachment behind to the Flexor brevis digitorum muscle. The lateral portions of the plantar fascia covers the sides of the foot. The outer portion covers the under surface of the Abductor minimi digiti; it is very thick behind, thin in front, and extends from the os ealcis forwards to the base of the fifth metatarsal bone, into the outer side of which it is inserted; it is continuous internally with the middle portion of the plantar fascia, and exter- nally with the dorsal fascia. The inner portion is very thin, and covers the Abductor pollicis muscle; it is attached behind to the internal annular ligament, is continuous around the side of the foot Avith the dorsal fascia, and externally with the middle portion of the plantar fascia. OF THE FOOT. 299 Muscles of the Foot. These are divided into two groups: 1. Those on the dorsum ; 2. Those on the plantar surface. 1. Dorsal Region. Extensor Brevis Digitorum. The Fascia on the dorsum of the foot is a thin membranous layer, continuous above with the anterior margin of the annular ligament; it becomes gradually lost in front, opposite the heads of the metatarsal bones, and on each side blends Avith the lateral portions of the plantar fascia : it forms a sheath for the tendons placed on the dorsum of the foot. On the removal of this fascia, the muscles of the dorsal region of the foot are exposed, covered by their investing fascia. The Extensor Brevis Digitorum, is a thin and someAvhat broad muscle, Avhich arises by a rounded extremity from the outer side of the os ealcis, in front of the groove for the Peroneus brevis, from the astragalo-calcanean ligament, and from the anterior annular ligament of the tarsus : passing obliquely across the dorsum of the foot, it terminates in four tendons. The innermost, which is the largest, is inserted into the first phalanx of the great toe ; the other three into the outer sides of the long extensor tendons of the second, third, and fourth toes. Relations. By its superficied surface, with the fascia of the foot, the tendons of the Extensor longus digitorum, and Extensor proprius pollicis. By its deep sur- face, Avith the tarsal and metatarsal bones, and the Dorsal interossei muscles. Nerves. It is supplied by the anterior tibial nerve. Actions. The Extensor brevis digitorum is an accessory to the long Extensor, extending the phalanges of the four inner toes, but acting only on the first pha- lanx of the great toe. The obliquity of its direction counteracts the oblique move- ment given to the toes by the long Extensor, so that both muscles acting together, the toes are evenly extended. 2. Plantar Region. The muscles in the plantar region of the foot may be divided into three groups, in a similar manner to those in the hand. Those of the internal plantar region are connected with the great toe, and correspond witli those of the thumb ; those of the external plantar region are connected with the little toe, and correspond with those of the little finger ; and those of the middle plantar region are con- nected with the tendons intervening betAveen the tAvo former groups. The Inter- ossei are considered separately. Internal Plantar Group. External Plantar Group. Abductor Pollicis. Abductor Minimi Digiti. Flexor Brevis Pollicis. Flexor Brevis Minimi Digiti. Adductor Pollicis. Transversus Pedis. 3 Del die Plantar Group. Flexor Brevis Digitorum. Musculus Accessorius. Lumbricales. In order to facilitate their dissection, it will be found more convenient to divide them into three layers, as they present themselves, in the order in which they are successively exposed. First Layer. Abductor Pollicis. Flexor Brevis Digitorum. Abductor Minimi Digiti. Dissection. Remove the fascia on the inner and outer sides of the foot, commencing in front over the tendons, and proceeding backwards. The central portion should be divided transverselv in the middle of the foot; and the two flaps dissected forwards and backwards. 300 MUSCLES AND FASCRE. The Abductor Pollicis lies along the inner border of the foot. It arises from the inner tuberosity of the os ealcis, from the internal annular ligament, from the plantar fascia, and from the intermuscular septum between it and the Flexor brevis digitorum. The fibres terminate in a tendon, Avhich is inserted, together with the innermost tendon of the Flexor brevis pollicis, into the internal sesamoid bone and inner border of the base of the first phalanx of the great toe. Relations. By its superficied surface, with the internal plantar fascia. By its deep surface, with the Flexor brevis Fig. 17G. -Muscles of the Sole of the Foot. First Layer. pollicis, the Musculus accessorius, and the tendons of the Flexor longus digi- torum and Flexor longus pollicis, the Tibialis anticus and posticus, the plan- tar vessels and nerves, and the articula- tions of the tarsus. The Flexor Brevis Digitorum lies in the middle line of the sole of the foot^ immediately beneath the plantar fascia, witli Avhich it is firmly united. It arises, by a narroAv tendinous pro- cess, from the inner tuberosity of the os ealcis, from the central part of the plantar fascia, and from the intermus- cular septa betAveen it and the adja- cent muscles. It passes forAvards and divides into four tendons. Opposite the middle of the first phalanges, each tendon presents a longitudinal slit, to allow of the passage of the correspond- ing tendon of the Flexor longus digito- rum, the tAvo portions forming a groove for ^ its reception, and, after reuniting, divides a second time into two. pro- cesses, which are inserted into the sides of the second phalanges. The mode of division of the tendons of the Flexor brevis digitorum, and their in- sertion into the phalanges, is analogous to the Flexor sublimis in the hand. dictations. By its superficial sur- face, Avith the plantar fascia. By its deep surface, with the Musculus acces- sorius, the Lumbricales, the tendons of the Flexor longus digitorum, and the plantar vessels and nerves, from which it is separated by a thin layer of fascia. The outer and inner borders are separated from the adjacent mus- cles by means of vertical prolongations mi An tit- °f ^e plantar fascia. Ihe Abductor Minimi Digiti lies along the outer border of the foot. It arises, by a very broad origin, from the outer tuberosity of the os ealcis, from the under surface of the os ealcis in front of both tubercles, from the outer portion of the plantar tascia, and the intermuscular septum between it and the Flexor brevis digitorum Its tendons, after gliding over a smooth facet on the under surface of the base of the fifth metatarsal bone, is inserted into the outer side of the base of the first phalanx of the little toe. Relations. By its superficial surface, with the outer portion of the plantar OF THE SOLE OF THE FOOT. 301 177, -Muscles of the Sole of the Foot. Second Layer. fascia. By its deep surface, Avith the outer head of the Musculus accessorius, the Flexor brevis minimi digiti, the long plantar ligament, and Peroneus longus. Its inner side is separated from the Flexor brevis digitorum by a vertical septum of fascia. Dissection. The muscles of the superficial layer should be divided at their origin, by in- serting the knife beneath each, and cutting obliquely backwards, so as to detach them from the bone; they should then be drawn forwards, in order to expose the second layer, but not separated from their insertion. The two layers are separated by a thin membrane, the deep plantar fascia, on the removal of which is seen the tendon of the Flexor longus digitorum, with its accessory muscle, the Flexor longus pollicis and the Lum- bricales. The long flexor tendons cross each other at an acute angle, the Flexor longus pollicis running along the inner side of the foot, on a plane superior to that of the Flexor longus digitorum, the direc- tion of which is obliquely outwards. Second Layer. Flexor Accessorius. Lumbricales. The Flexor Accessorius arises pos- teriorly by tAvo heads, the inner or larger, Avhich is muscular, being at- tached to the inner concave surface of the os ealcis and to the calcaneo- scaphoid ligament; the outer head, flat and tendinous, to the under sur- face of the os ealcis, in front of its outer tuberosity, and to the long plantar ligament : the tAvo portions become united at an acute angle, and are inserted into the outer margin and upper and under surfaces of the tendon of the Flexor longus digitorum, forming a kind of groove, in Avhich the tendon is lodged. A feAV fibres from the upper surface of the muscle blend Avith a tendinous expansion from the Flexor longus pollicis. Relations. By its superficial sur- face, Avith the muscles of the super- ficial layer, from Avhich it is separated by the external plantar vessels and nerves. By its deep surface, Avith the os ealcis and long calcaneo-cuboid liga- ment. The Lumlndcales are four small muscles, accessory to the tendons of the Flexor longus digitorum : they arise from the tendons of the long Flexor, as far back as their angle of division, each arising from two tendons, except the in- ternal one. Each muscle terminates in a tendon, Avhich passes forwards on the inner side of each of the lesser toes, and is inserted into the expansion of the long Extensor and base of the second phalanx of the corresponding toe. Dissection. The flexor tendons should be divided at the back part of the foot, and the Mus- culus accessorius at its origin, and drawn forwards, in order to expose the third layer. 302 MUSCLES AND FASCIA. Flexor Brevis Pollicis Adductor Pollicis. Third Layer. Flexor Brevis Minimi Digiti. Transversus Pedis. Fig. 178.—Muscles of the Sole of the Foot. Third Layer. The Flexor Brevis Pollicis arises, by a pointed tendinous process, from the inner border of the cuboid bone, from the contiguous portion of the external cuneiform, and from the prolongation of the tendon of the Tibialis posticus, which is attached to that bone. The muscle divides, in front, into tAvo portions. which are inserted into the inner and outer sides of the base of the first phalanx of the great toe, a sesamoid bone being developed in each tendon at its insertion. The inner head of this muscle is blended with the Ab- ductor pollicis previous to its insertion; the outer head, with the Adductor pol- licis ; and the tendon of the Flexor longus pollicis lies in a groove between them. Relations. By its superficial sur- face, with the Abductor pollicis, the tendon of the Flexor longus pollicis and plantar fascia. By its deep sur- face, Avith the tendon of the Peroneus longus, and metatarsal bone of the great toe. By its inner border, with the Abductor pollicis. By its outer border, Avith the Adductor pollicis. The Adductor Pollicis is a large, thick, fleshy mass, passing obliquely across the foot, and occupying the hol- Ioav space betAveen the four outer meta- tarsal bones. It arises from the tarsal extremities of the second, third, and fourth metatarsal bones, and from the sheath of the tendon of the Peroneus longus ; and is inserted, together with the outer head of the Flexor brevis pollicis, into the outer side of the base of the first phalanx of the great toe. The Flexor Brevis Minimi Digiti is situated along the outer border of the metatarsal bone of the little toe. It arises from the base of the metatarsal bone of the little toe, and from the sheath of the Peroneus longus; its tendon is inserted into the base of the first phalanx of the little toe, on its outer side. Relations. By its superficial surface, with the plantar fascia and tendon of the Abductor minimi digiti. By its deep surface, with the fifth metatarsal bone. The Transversus Pedis, is a narrow, flat, muscular fasciculus, stretched trans- versely across the heads of the metatarsal bones, between them and the flexor tendons. It arises from the under surface of the head of the fifth metatarsal bone, and from the transverse ligament of the metatarsus; and is inserted into the outer side of the first phalanx of the great toe, its fibres being blended with the tendon of insertion of the Adductor pollicis. OF THE SOLE OF THE FOOT. 303 Relations. By its under surface, Avith the tendons of the long and short Flexors and Lumbricales. By its upper surface, with the Interossei. • The Interossei. The Interossei muscles in the foot are similar to those in the hand. They are seven in number, and consist of tAvo groups, dorsal and plantar. The Dorsal Jnterossei, four in number, are situated betAveen the metatarsal bones. They are bipenniform muscles, arising by tAvo heads from the adjacent sides of the metatarsal bones betAveen which they are placed, their tendons being inserted into the bases of the first phalanges, and into the aponeurosis formed by the common extensor tendon. In the angular interval left betAveen each muscle at its posterior extremity, the perforating arteries pass to the dorsum of the foot; except in the first Interosseous muscle, Avhere the interval alloAvs the passage of the communicating branch of the dor- salis pedis artery. The first Dorsal interosseous muscle is inserted into the inner side of the second toe; the other three are inserted into the outer sides of the second, third, and fourth toes. They are all abductors from an imaginary line or axis drawn through the second toe. The Plantar Interossei, three in number, lie be- neath, rather than betAveen, the metatarsal bones. They are single muscles, and are each connected with but one metatarsal bone. They arise from the base and inner sides of the shaft of the third, fourth, and fifth metatarsal bones, and are inserted into the inner sides of the bases of the first phalanges of the same toes, and into the aponeurosis of the common extensor tendon. These muscles are all adductors, towards an imaginary line, extending through the second toe. Nerves. The internal plantar nerve supplies the Abductor pollicis, Flexor brevis digitorum, Flexor brevis pollicis, and the first and second Lumbricales. The external plantar nerve supplies the Abductor minimi digiti, Musculus accessorius, third and fourth Lumbricales, Adductor pollicis, Flexor brevis minimi digiti, Transversus pedis, and all the Interossei. SURCICAL ANATOMY. The student should noAV consider the effects produced by the action of the various muscles, in fractures of the bones of the lower extre- mity. The more common forms of fracture have been especially selected for illustration and de- scription. Fig. 179, -The Dorsal Interossei. Left Foot. 180, -The Plantar Interossei. Left Foot. 301 SURGICAL ANATOMY. Fig. 181.—Fracture of the Neck of the Femur within the Fracture of the neck of .Capsular Ligament. ^ femm% internal to ffl(J capsular ligament (Fig. 181) is a very common accident, and is most frequently caused by indirect violence, such as slipping off the edge of the curbstone, the im- petus and Aveight of the body falling upon the neck of the bone. It usually occurs in females, and sel- dom under fifty years of nUS age. At this period of life, the neck of the bone, under certain conditions of the system, assumes a ho- rizontal instead of an ob- lique direction, the head being on a level Avith the trochanter major ; the can- cellous tissue of the neck becomes soft and infiltrated with fatty matter, the com- pact tissue is partially Fig. 182.—Fracture of the Femur absorbed, and the amount of earthy matter becomes below the Trochanter Minor. greater in proportion to the animal constituent; hence, the bones are brittle, and more liable to fracture. The characteristic marks of this accident are slight shortening of the limb, and eversion of the foot, neither of which symptoms occur, hoAvever, in some cases, until a short time after the injury. The eversion is caused by the combined action of the external rotator muscles, as Avell as by the Psoas and Iliacus, Pectineus, Adductors, and Gluttei muscles. The shortening and retraction of the limb is produced by the action of the Glutnei, and by the Rectus femoris in front, and the Biceps, Semitendinosus, and Semi- membranosus behind. Fracture of the femur below the trochanter minor (Fig. 182) is an accident of not unfrequent occurrence, and is attended Avith great displacement, producing considerable deformity. The upper fragment, the portion chiefly displaced, is tilted forAvards, almost at right angles with the pelvis, by the combined action of the Psoas and Iliacus, and at the same time everted and drawn outAvards by the external rotator and Glutsei muscles, causing a marked prominence at the upper and outer side of the thigh, and much pain from the bruising and laceration of the muscles. The limb is shortened, from the lower frag- ment being drawn upAvards by the Rectus in front, and the Biceps, Semimembranosus, and Semitendi- nosus behind ; and at the same time everted, and the upper end thrown outAvards, the lower inwards, by the Pectineus and Adductor muscles. This fracture may SEMI- TENOIN. OF THE MUSCLES OF THE LOWER EXTREMITY. 305 Fig. 183.—Fracture of the Femur above the Condyles. be reduced in two different methods : either by direct relaxation of all the opposing muscles, to effect which the limb should be placed on a double inclined plane" or by overcoming the contraction of the muscles by continued extension, which may be effected by means of the long splint. Oblique fracture of the femur immediately above the condyles (Fig. 183) is a formidable injury, and attended with considerable displacement. On exami- nation of the limb, the lower fragment may be felt deep in the popliteal space, being drawn backwards by the Gastrocnemius, Soleus, and Plantaris muscles, and upwards by the Rectus and Posterior femoral muscles. The pointed end of the upper fragment is drawn inwards bythe Pectineus and Adductor muscles, and tilted forAvards by the Psoas and Iliacus, piercing the Rectus muscle, and occasionally the integument. Relaxation of these muscles, and direct approxima- tion of the broken fragments, is effected by placing the limb on a double inclined plane. The greatest care is requisite in keeping the pointed extremity of the upper fragment in proper apposition ; othenvise, after union of the fracture, extension of the limb is partially destroyed from the Rectus muscle being held doAvn by the fractured end of the bone, and from the patella Avhen elevated being draAvn upAvards against it. Fracture of the patella (Fig. 184) may be produced by muscular action, or by direct violence. When produced by muscular action, it occurs thus in danger of falling forAvards, attempts to recover himself by throwing the body backwards, and the violent action of the Quadriceps extensor upon the patella snaps that bone transversely across. The upper fragment is drawn up the thigh by the Quadri- ceps extensor, the loAver fragment being retained in its position by the ligamentum patellae ; the extent of separation of the tAvo fragments depending upon the degree of laceration of the ligamentous structures around the bone. The patient is totally unable to straighten the limb ; the prominence of the patella is lost; and a marked but varying interval can be felt betAveen the fragments. The treatment consists in relaxing the opposing muscles, which may be effected by raising the trunk, and slightly elevating the limb, which should be kept in a straight position. Union is usually ligamentous. In fracture from direct violence, the bone is generally comminuted, or fractured ob- liquely or perpendicularly. Oblique fracture of the shaft of the tibia (Fig. 185) usually occurs at the lower fourth of the bone, this being the narrowest and Aveakest part, and is generally ac- companied with fracture of the fibula. If the fracture has taken place obliquely from above, downwards and forwards, the fragments ride over one another, the lower fragment being draAvn backAvards and upwards by the powerful action of the muscles of the calf; the pointed extremity of the upper fragment pro- jects forAvards immediately beneath the integument, often protruding through it, and rendering the fracture a compound one. If the direction of the fracture is the reverse of that shoAvn in the figure, the pointed extremity of the lower fragment projects forAvards, riding upon the loAver end of the upper one. By relaxing the opposing muscles (bending the knee), with the extension made from 22 perso Fig. 184.—Fracture of the Patella. 306 SURGICAL ANATOMY. Fig. 185.—Oblique Fracture of the Shaft of the Tibia. the knee and ankle, the fragments may be brought into apposition. It is often necessary, however, in compound fracture to remove a portion of the projecting bone with the saw before complete adaptation can be effected. Fracture of the fibula, with dislocation of the tibia inwards (Fig. 186), commonly known as "Pott's Fracture," is one of the most frequent injuries of the ankle joint. The end of the tibia rests upon the inner side of the astragalus, the internal lateral ligament of the ankle joint is ruptured, and the inner malleolus projects inAvards beneath the integument, Avhich is tightly stretched over it, and in danger of bursting. The fibula is broken usually about three inches above the ankle, and occasionally that por- tion of the tibia with which it is more directly connected below ; the foot is everted by the action of the Peroneus longus, its inner border resting upon the ground, and, at the same time, the heel is drawn up by the muscles of the calf. This injury may be at once reduced by flexing the leg at right angles with the thigh, which relaxes all the opposing muscles, and by making slight ex- tension from the knee and ankle. Fig. 186.—Fracture of the Fibula, with dislocation of the Tibia inwards. "Pott's Fracture." Of the Arteries. HHHE Arteries are cylindrical tubular vessels, which serve to convey blood from the *- heart to every part of the body. These vessels Avere named arteries (arjp rr^jsiv, " to contain air"), from the belief entertained by the ancients that they contained air. To Galen is due the honor of refuting this opinion; he showed that these vessels, though for the most part empty after death, contained blood in the living body. The pulmonary artery, which arises from the right ventricle of the heart, carries venous blood directly into the lungs, from Avhence it is returned by the pulmonary veins into the left auricle. This constitutes the lesser or pulmonic circulation. The great artery which arises from the left ventricle, the aorta, conveys arterial blood to the body generally ; from Avhence it is brought back to the right side of the heart by means of the veins. This constitutes the greater or systemic circulation. The distribution of the systemic arteries is like a highly ramified tree, the com- mon trunk of which, formed by the aorta, commences at the left ventricle of the heart, the smallest ramifications corresponding to the circumference of the body and the contained organs. The arteries are found in nearly every part of the animal body, Avith the exception of the hairs, nails, and epidermis; and the larger trunks usually occupy the most protected situations, running, in the limbs, along the flexor side, Avhere they are less exposed to injury. There is considerable variation in the mode of division of the arteries; occa- sionally a short trunk subdi\ldes into several branches at the same point, as Ave observe in the coeliac and thyroid axes; or the vessel may give off several branches in succession, and still continue as the main trunk, as is seen in the arteries of the limbs; but the usual division is dichotomous, as, for instance, the aorta dividing into the two common iliacs; and the common carotid, into the external and internal. The branches of arteries arise at very variable angles; some, as the superior intercostal, arise from the aorta at an obtuse angle; others, as the lumbar arteries, at a right angle; or, as the spermatic, at an acute angle. An artery from which a branch is given off is smaller in size than the trunk from which it arises, but retains a uniform diameter until a second branch is derived from it; but if an artery divides into tAvo branches, the combined area of the tAvo vessels is, in nearly every instance, someAvhat greater than that of the trunk; and the combined area of all the arterial branches greatly exceeds the diameter of the aorta; so that the arteries collectively may be regarded as a cone, the apex of Avhich corresponds to the aorta; the base, to the capillary system. The arteries, in their distribution, communicate freely Avith one another, forming Avhat is called an anastomosis (a>«, "between;" erro/ia, "mouth"), or inosculation, and this communication is very free betAveen the large, as Avell as between the smaller branches. The anastomoses between trunks of equal size is found where great freedom and activity of the circulation is requisite, as in the brain; here the two vertebral arteries unite to form the basilar, and the two internal carotid arte- ries are connected by a short intercommunicating trunk; it is also found in the abdomen, the intestinal arteries having very free anastomoses betAveen their larger branches. In the limbs, the anastomoses are most frequent and of largest size around the joints, the branches of an artery above, freely inosculating Avith branches from the vessel below; these anastomoses are of considerable interest to the surgeon, as it is by their enlargement that a collateral circulation is established after the application of a ligature to an artery for the cure of aneurism. The smaller branches of arteries anastomose more frequently than the larger, and betAveen the smallest tAvigs these inosculations become so numerous as to constitute a close network that pervades nearly every tissue of the body. Throughout the body generally the larger arterial branches pursue a perfectly straight course, but in certain situations they are tortuous; thus the facial artery in its course over the face, and the labial arteries of the lips, are extremely tor- tuous in their course, to accommodate themselves to the movements of these parts. 308 ARTERIES. The uterine arteries are also tortuous, to accommodate themselves to the increase of size which this organ undergoes during pregnancy. Again, the internal carotid and vertebral arteries, previous to their entering the cavity of the skull describe a series of curves, which are evidently intended to diminish the velocity of the current of blood, by increasing the extent of surface over which it moves and adding to the amount of impediment Avhich is produced from friction. The smaller arterial branches terminate in a system of minute anastomosing vessels which pervade every tissue of the body. These vessels, from their minute size, are termed capillaries (capillus, a hair). They are interposed betAveen the smallest branches of the arteries and the commencing veins, constituting a net- work, the branches of Avhich are of nearly uniform size, their average diameter being about the g^o of an inch; but the size of the smaller capillaries, and the diameter of the meshes between them, vary in the different organs. The arteries are dense in structure, of considerable strength, highly elastic and when divided, they preserve, although empty, their cylindrical form. They are composed of three coats, internal, middle, and external. The internal is an epithelial and elastic coat; it consists of tAvo layers, the inner- most of which is composed of a single layer of elliptical or spindle-shaped epithe- lial particles, with round or oval nuclei, resting upon a striated and perforated transparent colorless membrane, highly elastic, but extremely thin and brittle disposed in one or more layers, and forming the chief substance of the inner coat! The middle or contractile coat, consists of muscular and elastic fibres; it is of a reddish-yellow color, highly elastic, and consists of numerous layers' of non- striated muscular fibres, disposed in a circular form around the vessels, having inter- mixed with them layers of fine elastic or fenestrated membrane; as many as forty layers have been counted in the aorta, twenty-eight in the carotid, and fifteen in the subclavian artery. The muscular tissue exists in greatest abundance in the smallest arteries, whilst in the larger trunks it is blended with much elastic tissue; the great thickness of the walls of the arteries is due chiefly to this coat. The external, or areolar and elastic coat, consists of condensed areolar and elastic tissue ; in the larger arteries it is composed of two distinct layers: an inner, composed of elastic tissue, most distinct in the larger arteries; and an external layer of condensed areolo-fibrous tissue, the constituent fibres being disposed more or less diagonally or obliquely around the vessel. In the smaller arteries the elastic tissue is wanting, the areolar coat increasing in proportion. Some arteries have extremely thin coats in proportion to their size; this is especially the case in those situated in the cavity of the cranium and spinal canal, the difference depending upon the greater thinness of the external and middle coats. lie arteries, in their distribution throughout the body, are included in a thin areolo-fibrous investment, which forms what is called their sheath. In the limbs, this is usually formed by a prolongation of the deep fascia; in the upper part of the thigh it consists of a continuation downwards of the transversalis and iliac tascue of the abdomen; in the neck, of a prolongation of the deep cervical fascia. llie included vessel is loosely connected with its sheath bv a delicate areolar tissue; and the sheath usually incloses the accompanying veins and sometimes a nerve. Some arteries, as those in the cranium, are not included in sheaths. Arteries are supplied with bloodvessels like the other organs of the body, which are called vasa versorum. These nutrient vessels arise from a branch of the artery or from a neighboring vessel, at some considerable distance from the point at which they are distributed : they ramify in the loose areolar tissue connecting the' artery with its sheath, and are distributed to the external and middle coats, and, according to Arnold and others, supply the internal coat, Minute veins serve to return the blood from these vessels; they empty themselves into the ven* comites m connection with the artery. Arteries are also provided with nerves; they arc derived chiefly from the sympathetic, but partly from the cerebro-spinal system. Ihey form intricate plexuses upon the surface "of the larger trunks, the smaller branches being usually accompanied by single filaments; their exact mode of distribution is unknoAvn. GENERAL ANATOMY. 309 In the description of the arteries, Ave shall first consider the efferent trunk of the systemic circulation, the aorta and its branches: and then the efferent trunk of the pulmonic circulation, the pulmonary artery. The Aorta. The aorta («'Y>-v?; arteria magna) is the main trunk of a series of vessels, which, arising from the heart, conveys the red oxygenated blood to every part of the body for its nutrition. This vessel commences at the upper part of the left Fig. 187.—The Arch of the Aorta and its Branches. ventricle, and, after ascending for a short distance, arches backwards to the left side, over the root of the left lung, descends within the thorax on the left side of the vertebral column, passes through the aortic opening in the Diaphragm, and, entering the abdominal cavity, terminates, considerably diminished in size, oppo- site the fourth lumbar vertebra, where it divides into the right and left common iliac arteries. Hence its subdivision into the arch of the aorta, the thoracic aorta, and the abdominal aorta, from the direction or position peculiar to each part. Arch of the Aorta. Dissection. In order to examine the arch of the aorta, the thorax should be opened by dividing the cartilages of the ribs on each side of the sternum, and raising this bone from 310 ARTERIES. below upwards, and then sawing through the sternum on a level with its articulation with the clavicle. By this means the relations of the large vessels to the upper border of the sternum and root of the neck are kept in view. The arch of the aorta extends from the origin of the vessel at the upper part of the left ventricle, to the lower border of the body of the third dorsal vertebra. At its commencement, it ascends behind the sternum, obliquely upAvards and for- Avards* towards the right side, and opposite the upper border of the second costal cartilage of the right side, passes transversely from right to left, and from before backAvards to the left side of the second dorsal vertebra ; it then descends upon the left side of the body of the third dorsal vertebra, at the loAver border of which it becomes the thoracic aorta, Hence this portion of the vessel is divided into an ascending, a transverse, and a descending portion. The artery in its course describes a curve, the convexity of which is directed upAvards and to the right side, the con- cavity in the opposite direction. Ascending Part of the Arch. The ascending portion of the arch of the aorta is about tAvo inches in length. It commences at the upper part of the left ventricle, in front of the left auriculo- ventricular orifice, and opposite the middle of the sternum, on a line with its junc- tion to the third costal cartilage ; it passes obliquely upAvards in the direction of the heart's axis, to the right side, as high as the upper border of the second costal cartilage, describing a slight curve in its course, and being situated, Avhen dis- tended, about a quarter of an inch behind the posterior surface of the sternum. A little above its commencement, it is somewhat enlarged, and presents three small dilatations, called the sinuses of the aorta (sinuses of Valsalva), opposite to which are attached the three semilunar valves, which serve the purpose of preventing any regurgitation of blood into the cavity of the ventricle. A section of the aorta opposite this part has a somewhat triangular figure; but beloAv the attach- ment of the valves it is circular. This portion of the arch is contained in the cavity of the pericardium, and, together with the pulmonary artery, is invested in a tube of serous membrane, continued on to them from the surface of the heart. Relations. The ascending part of the arch is covered at its commencement by the trunk of the pulmonary artery and the right auricular appendage, and, higher up, is separated from the sternum by the pericardium, some loose areolar tissue, and the remains of the thymus gland ; behind, it rests upon the right pulmonary vessels and root of the right lung. On the right side, it is in relation with the superior vena cava and right auricle; on the left side, with the pulmonary artery. Plan of the Relations of the Ascending Part of the Arch. In front. Pulmonary artery. Right auricular appendage. Pericardium. Remains of thymus gland. RUjld sb/c /i\rch"\ Superior cava. ( f Aorte" \ Left side. Right auricle. \PorUou / Pulmonary artery. Beh in el. Ri^ht pulmonary vessels. Root of riuht lumr. Transverse Part of the Arch. The second or transverse portion of the arch commences at the upper border of the second costo-sternal articulation of the right side in front, and passes from right to left, and from before backwards, to the left side of the second dorsal ARCH OF AORTA. 311 vertebra behind. Its upper border is usually about an inch beloAV the upper margin of the sternum. Relations. Its anterior surface is covered by the left pleura and lung, and crossed towards the left side by the left pneumogastric and phrenic nerves, and cardiac branches of the sympathetic. Its posterior surface lies on the trachea just above its bifurcation, the great cardiac plexus, the oesophagus, thoracic duct, and left recurrent laryngeal nerves. Its superior border is in relation Avith the left innominate vein; and from its upper part are given off the innominate, left carotid, and left subclavian arteries. By its lower border, with the bifurcation of the pulmonary artery, and the remains of the ductus arteriosus, Avhich is con- nected Avith the left division of that vessel; the left recurrent laryngeal nerve winds round it, Avhilst the left bronchus passes beloAv it. Plan of the Relations of the Transverse Part of the Arch. Above. Left innominate \"ein. Arteria innominata. Left carotid. Left subclavian. In front. Left pleura and lung. Left pneumogastric nerve. Left phrenic nerve. Cardiac nerves. Arch of Aorta. Transverse V Portion. Behind. Trachea. Cardiac plexus. (Esophagus. Thoracic duct. Left recurrent nerve. Below. Bifurcation of pulmonary artery. Remains of ductus arteriosus. Left recurrent nerve. Left bronchus. Descending Part of the Arch. The descending portion of the arch has a straight direction, inclining downwards on the left side of the body of the third dorsal vertebra, at the loAver border of which it becomes the thoracic aorta, Relations. Its anterior surface is covered by the pleura and root of the left lung; behind, it lies on the left side of the body of the third dorsal Arertebra. On its right side lie the oesophagus and thoracic duct; on its left side it is covered by the pleura. Plan of the Relations of the Descending Part of the Arch. In front. Pleura. Root of left lung. Right side. (Esophagus. Thoracic duct. Arch of Aorta. (Descending) Portion. Left side. Pleura. Behind. Left side of body of third dorsal vertebra. The ascending, transverse, and descending portions of the arch vary in position according to the movements of respiration, being loAvered, together Avith the trachea, bronchi, and pulmonary vessels, during inspiration, by the descent of the diaphragm, and elevated during expiration, Avhen the diaphragm ascends. These movements are greater in the ascending than the transverse, and in the latter than the descending part. Peculiarities. The height to which the aorta rises in the chest is usually about an inch below the upper border of the sternum ; but it may ascend nearly to the top of that bone. Occasionally it is found an iuch and a half, more rarely three inches, below this point. 312 ARTERIES. Direction Sometimes the aorta arches over the root of the right instead of the left, luno* as in birds, and passes down on the right side of the spine. In such cases, all the viscera of the thoracic and abdominal cavities are transposed. Less frequently, the aorta, after arching over the right lung, is afterwards directed to its usual position on the left side of the spine, this peculiarity not being accompanied by any transposition of the viscera. Conformation. The aorta occasionally divides into an ascending and a descending trunk as in some quadrupeds, the former being directed vertically upwards, and subdividing into three branches, to supply the head and upper extremities. Sometimes the aorta subdivides soon after its origin into two branches, which soon reunite. In one of these cases, the oesophagus and trachea were found to pass through the interval left by their division; this is the normal condition of the vessels in the reptilia. Surgical Anatomy. Of all the vessels of the arterial system, the aorta, and more espe- cially its arch, is most frequently the seat of disease; hence it is important to consider some of the consequences that may ensue from aneurism of this part. It will be remembered, that the ascending part of the arch is contained in the pericar- dium, just behind the sternum, its commencement being crossed by the pulmonary artery and right auricular appendage, having the»root of the right lung behind, the vena cava on the right side, and the pulmonary artery and left auricle on the left side. Aneurism of the ascending aorta, in the situation of the aortic sinuses, in the great majority of cases, affects the right coronary sinus; this is mainly owing to the regurgi- tation of blood upon the sinuses taking place chiefly on the right anterior aspect of the vessel. As the aneurismal sac enlarges, it may compress any or all of the structures in immediate proximity with it, but chiefly projects towards the right anterior side; and, consequently, interferes mainly with those structures that have a corresponding relation with the vessel. In the majority of cases, it bursts in the cavity of the pericardium, the patient suddenly drops down dead, and, upon a post-mortem examination, the pericardial bag is found full of blood : or it may compress the right auricle, or the pulmonary artery and adjoining part of the right ventricle, and open into one or the other of these parts, or it may compress the superior cava. Aneurism of the ascending aorta, originating above the sinuses, most frequently impli- cates the right anterior wall of the vessel; this is probably mainly owing to the blood being impelled against this part. Its direction is also chiefly towards the right of the median line. If it attains a large size and projects forwards, it may absorb the sternum and the cartilages of the ribs, usually on the right side, and appear as a pulsating tumor on the front of the chest, just below the manubrium; or it may burst into the pericardium, may compress or even open into the right lung, the trachea, bronchi, or oesophagus. Regarding the transverse part of the arch, the student is reminded that the vessel lies on the trachea, the oesophagus, and thoracic duct; that the recurrent laryngeal nerve winds around it; and that from its upper part are given off three large trunks, which supply the bead, neck, and upper extremities. Now an aneurismal tumor taking origin from the posterior part or right aspect of the vessel, its most usual site, may press upon the trachea, impede the breathing, or produce cough, haemoptysis, or stridulous breathing, or it may ultimately burst into that tube, producing fatal hemorrhage. Again, its pressure on the laryngeal nerves may give rise to symptoms which so accurately resemble those of laryngitis, that the operation of tracheotomy has in some cases been resorted to, from the supposition that disease existed in the larynx; or it may press upon the thoracic duct, and destroy life by inanition; or it may involve the oesophagus, producing dysphagia; or may burst into this tube, when fatal hemorrhage will occur. Again, the innominate artery, or the left carotid, or subclavian, may be so obstructed by clots, as to produce a weakness, or even a disappearance, of the pulse in one or the other Avrist; or the tumor may present itself at or above the manubrium, generally either in the median line, or to the right of the sternum. Aneurism affecting the descending part of the arch is usually directed backwards and to the left side, causing absorption of the vertebrae and corresponding ribs; or it may press upon the trachea, left bronchus, oesophagus, and the right and left lungs, generally the latter: when rupture of the sac occurs, this usually takes place in the left pleural cavity; less frequently in the left bronchus, the right pleura, or into the substance of the lungs or trachea. In this form of aneurism, pain is almost a constant and characteristic symptom, existing either in the back or chest, and usually radiating from the spine around the left side. This symptom depends upon the aneurismal sac compressing the intercostal nerves against the bone. CORONARY. 313 Branches of the Arch of the Aorta (Figs. 187, 188). The branches given off from the arch of the aorta are five in number : two of small size from the ascending portion, the right and left coronary ; and three of large size from the transverse portion, the innominate artery, the left carotid, and the left subclavian. Peculiarities, Position of the Branches. The branches, instead of arising from the highest part of the arch (their usual position), may be moved more to the right, arising from the commencement of the transverse or upper part of the ascending portion; or the distance from one another at their origin may be increased or diminished, the most frequent change in this respect being the approximation of the left carotid towards the innominate artery. The Number of the primary branches may be reduced to two : the left carotid arising from_the innominate artery; or, more rarely, the carotid and subclavian arteries of the left side arising from an innominate artery. But the number may be increased to four, from the right carotid and subclavian arteries arising directly from the aorta, the innomi- nate being absent. In most of these latter cases, the right subclavian arose from the left end of the arch ; in other cases, it was the second or third branch given off instead of the first. Lastly, the number of trunks from the arch may be increased to five or six : in these instances, the external and internal carotids arose separately from the arch, the common carotid being absent on one or both sides. Number usual, Arrangement different. When the aorta arches over to the right side, the three branches have an arrangement the reverse of what is usual, the innominate supply- ing the left side; and the carotid and subclavian (which arise separately), the right side. In other cases, where the aorta takes its usual course, the two carotids may be joined in a common trunk, and the subclavians arise separately from the arch, the right subclavian generally arising from the left end of the arch. S'-coiieian/ Branches sometimes arise from the arch : most commonly it is the left ver- tebral, which usually takes origin between the left carotid and left subclavian, or beyond them. Sometimes, a thyroid branch is derived from the arch, or the right internal mam- mary, or left vertebral, or, more rarely, both vertebrals. The Coronary Arteries. The coronary arteries supply the heart; they are two in number, right and left, arising near the commencement of the aorta, immediately above the free margin of the semilunar valves. The Right Coronary Artery, about the size of a croAv's quill, arises from the aorta immediately above the free margin of the right semilunar valve, betAveen the pulmonary artery, and the appendix of the right auricle. It passes forAvards to the right side in the groove between the right auricle and ventricle, and, curving around the right border of the heart, runs along its posterior surface as far as the posterior interventricular groove, where it divides into tAvo branches, one of which continues onwards in the groove between the left auricle and ventricle, and anasto- moses Avith the left coronary ; the other descends along the posterior interventri- cular furroAv, supplying branches to both ventricles, and to the septum, and anas- tomosing at the apex of the heart with the descending branch of the left coronary. This vessel sends a large branch along the thin margin of the right ventricle, to the apex, and numerous small branches to the right auricle and ventricle, and commencement of the pulmonary artery. The Left Coronary, smaller than the former, arises immediately above the free edge of the left semilunar valve, a little higher than the right; it passes forwards between the pulmonary artery and the left appendix auriculae, and descends ob- liquely towards the anterior interventricular groove, Avhere it divides into tAvo branches. Of these, one passes transversely outwards in the left auriculo-ventri- cular groove, and winds around the left border of the heart to its posterior surface, Avhere it anastomoses with the superior branch of the right coronary ; the other descends along the anterior interventricular groove to the apex of the heart, where it anastomoses with the descending branch of the right coronary. The left coronary supplies the left auricle and its appendix, both Arentricles, and numerous small branches to the pulmonary artery, and commencement of the aorta. Peculiarities. These vessels occasionally arise by a common trunk, or their number may 311 ARTERIES. be increased to three; the additional branch being of small size. More rarely, there are two. additional branches. Arteria Innominata. The innominate artery is the largest branch given off from the arch of the aorta. It arises from the commencement of the transverse portion in front of the left carotid, and, ascending obliquely to the upper border of the right sterno-clavicular articulation, divides into the right carotid and subclavian arteries. This vessel varies from an inch and a half to tAvo inches in length. Relations. In front, it is separated from the first bone of the sternum by the Sterno-hyoid and Sterno-thyroid muscles, the remains of the thymus gland, and by the left innominate and right inferior thyroid veins, which cross its root. Behind, it lies upon the trachea, Avhich it crosses obliquely. On the right side, is the right vena innominata, right pneumogastric nerve, and the pleura ; and on the left side, the remains of the thymus gland, and origin of the left carotid artery. Plan of the Relations of the Innominate Artery/. In front. Sternum. Sterno-hyoid and Sterno-thyroid. Remains of thymus gland. Left innominate and right inferior thyroid veins. Right side. Left side. Right vena innominata. /[nnominate\ ?e™ai"S °f' th'mja- Right pneumogastric nerve. ( ApfpPT7 J Left carotid. Pleura. V Behind. Trachea. Peculiarities in point of division. When the bifurcation of the innominate artery varies from the point above mentioned, it sometimes ascends a considerable distance above the sternal end of the clavicle; less frequently it divides below it. In the former class of cases, its length may exceed two inches ; and, in the latter, be reduced to an inch or less. These are points of considerable interest for the surgeon to remember in connection with the opera- tion of including this vessel in a ligature. Branches. The arteria innominata occasionally supplies a thyroid branch (middle thyroid artery), which ascends along the front of the trachea to the thyroid gland ; and sometimes, a thymic or bronchial branch. The left carotid is frequently joined with the innominate artery at its origin. Sometimes, there is no innominate artery, the right subclavian and right carotid arising directly from the arch of the aorta. Position When the aorta arches over to the right side, the innominate is directed to the Jett side of the neck, instead of to the right. Surgical Anatomy. Although the operation of tying the innominate artery has been performed by several surgeons, for aneurism of the right subclavian extending inwards as tar as the scalenus, in no instance has it been attended with success. An important fact has however, been established; viz., that the circulation in the parts supplied by the artery, can be supported after the operation ; a fact which cannot but encourage surgeons to have recourse to it whenever the urgency of the case may require it, notwithstanding that it must be regarded as peculiarly hazardous. The failure of the operation in those cases where it has been performed has depended on subsequent repeated secondary hemorrhage, or on inflammation of the adjoining pleural sac and lung. The main obstacles to its performance are, as the student will perceive from his dissection of this vessel, its. deep situation behind and beneath the sternum, and the number of important structures which surround it in every part. In order to apply a ligature to this vessel, the patient is placed upon his back, with the shoulders raised, and the head bent a little backwards, so as to draw out the artery from behind the sternum into the neck. An ineision two inches long is then made along the anterior border of the Sterno-mastoid muscle, terminating at the sternal end of the clavicle. Irom this point, a second incision is to be carried about the same length along the upper bor- der of the clavicle. The skin is to be dissected back, and the Platysma being exposed, must be divided on a director : the sternal end of the Sterno-mastoid is now brought into view, and COMMON CAROTID. 315 a director being passed beneath it, and close to its under surface, so as to avoid any small vessels, it must be divided transversely throughout the greater part of its attachment. Pressing aside any loose cellular tissue or vessels that may now appear, the Sterno-hyoid and Sterno-thyroid muscles will be exposed, and must be divided, a director being previously- passed beneath them. The inferior thyroid veins now come into view, and must be carefully drawn either upwards or downwards, by means of a blunt hook. On no account should these vessels be divided, as it would add much to the difficulty of the operation, and endanger its ultimate success. After tearing through a strong fibro-cellular lamina, the right carotid is brought into view, and being traced downwards, the arteria innominata is arrived at, The left vena innominata should now be depressed, the right vena innominata, the internal jugular vein, and pneumogastric nerve drawn to the right side; and a curved aneurism needle may then be passed around the vessel, close to its surface, and in a direction from below upwards :ind inwards : care being taken to avoid the right pleural sac, the trachea, and cardiac nerves. The ligature should be applied to the artery as high as possible, in order to allow room between it and the aorta for the formation of a coagulum. It has been seen that the failure of this operation depends either upon repeated secondary hemorrhage, or inflammation of the pleural sac and lung. The importance of avoiding the thyroid plexus of veins during the primary steps of the operation, and the pleural sac whilst including the vessel in the ligature, should be most carefully attended to. Common Carotid Arteries. The common carotid arteries, although occupying a nearly similar position in the neck, differ in position, and, consequently, in their relations at their origin. The right carotid arises from the arteria innominata, behind the right sterno-clavicular articulation ; the left from the highest part of the arch of the aorta. The left carotid is, consequently, longer and more deeply placed in the thorax. It will, therefore, be more convenient to describe first the course and relations of that portion of the left carotid Avhich intervenes between the arch of the aorta and the left sterno-clavicular articulation (see Fig. 187). The left carotid Avithin the thorax passes obliquely outwards from the arch of the aorta to the root of the neck. In front, it is separated from the first piece of the sternum by the Sterno-hyoid and Sterno-thyroid muscles, the left innominate vein, and the remains of the thymus gland ; behind, it lies on the trachea, oeso- phagus, and thoracic duct. Internedly, it is in relation Avith the arteria innomi- nata ; externally, with the left pneumogastric nerve, cardiac branches of the sym- pathetic, and left subclavian artery. Plan of the Relations of the Left Common Carotid. Thoracic Portion. In front. Sternum. Sterno-hyoid and Sterno-thyroid muscles. Left innominate vein. Remains of thymus gland. t Externally. Left pneumogastric nerve. Cardiac nerves. Left subclavian artery. Behind. Trachea. ' (Esophagus. Thoracic duet. In the neck, the tAvo common carotids resemble each other so closely, that one description "will apply to both. Starting from each side of the neck, these vessels pass obliquely upAvards, from behind the sterno-clavicular articulations, to a leArel with the upper border of the thyroid cartilage, where they divide into the external and internal carotids ; these names being derived, the former from their distribu- tion to the external parts of the head and face, the latter from their distribution 316 ARTERIES. to the internal parts of the cranium. The course of each vessel is indicated by a line draAvn from the sternal end of the clavicle beloAv, to a point midway betAveen the angle of the jaAv and the mastoid process abovTe. At the Ioavci' part of the neck the tAvo common carotid arteries are separated from each other by a very small interval, which corresponds to the trachea; but Fig. 189.—Surgical Anatomy of the Arteries of UieNeck Right Side. FIG.190. Flei n of tin Bremchcs ofUie EXTERNAL CAROTID \ at the upper part, the thyroid body, the larynx, and pharynx project forwards betAveen these vessels, and give the appearance of their being placed further back in this situation. The common carotid artery is contained in a sheath, derived trom the deep cervical fascia, which also incloses the internal jugular vein and pneumogastric nerve, the vein lying on the outer side of the artery, and the nerve between the artery and vein, on a plane posterior to both. On opening the sheath, these three structures are seen to be separated from one another, each being inclosed in a separate fibrous investment. Relations. At the lower part of the neck, the common carotid artery is verv deeply seated, being covered by the Platysma, superficial and deep fascia, the Sterno- COMMON CAROTID. 317 mastoid, Sterno-hyoid, and Sterno-thyroid muscles, and by the Omo-hyoid oppo- site the cricoid cartilage ; but in the upper part of its course, near its termination, it is more superficial, being covered merely by the integument, Platysma, the superficial and deep fasciae, and inner margin of the Sterno-mastoid, and is con- tained in a triangular space, bounded behind by the Sterno-mastoid, above by the posterior belly of the Digastric, and beloAV by the anterior belly of the Omo-hyoid. This part of the artery is crossed obliquely from Avithin outAvards by the sterno- mastoid artery ; it is also crossed by the superior thyroid veins, Avhich ter- minate in the internal jugular, and, descending on its sheath in front, is seen the descendens noni nerve, this filament being joined Avith branches from the cervical nerves, which cross the vessel from without inAvards. Sometimes the descendens noni is contained Avithin the sheath. The middle thyroid vein crosses it about its centre, and the anterior jugular vein beloAv, the latter vessel being usually placed beneath the Sterno-mastoid. Behind, the artery lies in front of the cervical por- tion of the spine, resting first on the Longus colli muscle, then on the Rectus anticus major, from Avhich it is separated by the sympathetic nerve. The recur- rent laryngeal nerve and inferior thyroid artery cross behind the vessel at its lower part. Internally, it is in relation Avith the trachea and thyroid gland, the inferior thyroid artery and recurrent laryngeal nerve being interposed; higher up, with the larynx and pharynx. On its outer side are placed the internal jugular vein and pneumogastric nerve. At the lower part of the neck, the internal jugular vein on the right side recedes from the artery, but on the left side it approaches it, and often crosses its loAver part. This arises from the circumstance of the veins on both sides having to pass towards the right side of the thorax. This is an important fact to bear in mind during the performance of any operation on the lower part of the left common carotid artery. Plan of the Relations of the Common Carotid Artery. In front. Integument and fasciae. Omo-hyoid: Platysma. Reseendens noni nerve. Sterno-mastoid. Sterno-mastoid artery. Sterno-hyoid. Superior and middle thyroid veins. Sterno-thyroid. Anterior jugular vein. Externally. Internally. Internal jugular vein. Trachea. Pneuuiogastiic nerve. Thyroid gland. Uommon - Recurrent laryngeal nerve. ', Urotld* J Inferior tbyroid'artery. / Larynx. Pharynx. Behind. Longus Colli. Sympathetic nerve. Rectus anticus major. Inferior thyroid artery. Recurrent laryngeal nerve. Peculiarities as to Origin. The right common carotid may arise above or below its usual point (the upper border of the sterno-clavicular articulation). This variation occurs in one out of about eight cases and a half, and is more frequently above than below the point- stated : or its origin may be transferred to the arch of the aorta, or it may arise in conjunc- tion with the left carotid. The left common carotid A'aries more frequently in its origin than the right. In the majority of cases it arises with the innominate artery, or where the innominate artery was absent, the two carotids arose usually by a single trunk. This vessel has a tendency towards the right side of the arch, occasionally being the first branch given off from the transverse portion. It rarely joins with the left subclavian, except in cases of transposition of the viscera. Point of Division. The most important peculiarities of this vessel, in a surgical point of view, relate to its place of division in the neck. In the majority of cases, this occurs higher than usual, the artery dividing into two branches opposite the hyoid bone, or even higher ; 318 ARTERIES. more rarely, it occurs below its usual place, opposite the middle of the larynx, or the lower border of the cricoid cartilage ; and one case is related by Morgagni, where this vessel, only an inch and a half in length, divided at the root of the neck. Aery rarely, the common carotid ascends in the neck without any subdivision, the internal carotid being wanting; and in two cases the common carotid has been found to be absent, the external and internal carotids arising directly from the arch of the aorta. This peculiarity existed on both sides in one subject, on one side in another. Occasional Branches. The common carotid usually gives off no branches, but it occasion- ally gives origin to the superior thyroid, or a laryngeal branch, the inferior thyroid, or, more rarely, the vertebral artery. Surgical Anatomy. The operation of tying the common carotid artery may be necessary in a wound of that vessel or its branches, in an aneurism, or in a case of pulsating tumor of the orbit or skull. If the wound involves the trunk of the common carotid itself, it will be necessary to tie the artery above and below the wounded part. If, however, one of the branches of that vessel is wounded, or has an aneurismal tumor connected with it, a ligature may be applied to any part of it, excepting its origin and termination. When the case is such as to allow a choice being made, the lower part of the carotid should never be selected as the spot upon which a ligature should be placed, for not only is the artery in this situa- tion placed very deeply in the neck, but it is covered by three layers of muscles, and on the left side the jugular vein, in the great majority of cases, passes obliquely over its front sur- face. Neither should the upper end be selected, for here the superior thyroid veins would give rise to very considerable difficulty in the application of a ligature. The point most favorable for the operation is opposite the lower part o*f the larynx, and here a ligature may be applied on the vessel, either above or below the point where it is crossed by the Omo- hyoid muscle. In the former situation, the artery is most accessible, and it may be tied there in cases of wounds, or aneurism of any of the large branches of the carotid; whilst in cases of aneurism of the upper part of the carotid, that part of the vessel may be selected whiclijs below the Omo-hyoid. It occasionally happens that the carotid artery bifurcates below its usual position : if the artery be exposed at its point of bifurcation, both divisions of the vessel should be tied near their origin, in preference to tying the trunk of the artery near its termination ; and if, in consequence of the entire absence of the common carotid, or from its early division, the two arteries, the external and internal carotids, are met with, the ligature should be placed on that vessel which is found on compression to be connected with the disease. In this operation, the direction of the vessel and the inner margin of the Sterno-mastoid are the chief guides to its performance. To tie the Common Carotid above the Omo-hyoid. The patient should be placed on his back with the head thrown back ; an incision is to be made, three inches long, in the direc- tion of the anterior border of the Sterno-mastoid, from a little below the angle of the jaw to a levelwith the cricoid cartilage; after dividing the integument, Platysma, and super- ficial fascia, the deep fascia must be cut through on a director, so as to avoid wounding numerous small veins that are usually found beneath. The head may now be brought for- wards so as to relax the parts somewhat, and the margins of the wound must be held asunder by copper spatulae. The descendens noni nerve is now exposed, and must be avoided, and the sheath of the vessel, having been raised by forceps, is to be opened over the artery to a small extent. The internal jugular vein will now present itself, alternately distended and relaxed; this should be compressed both above and below, and drawn outwards, in order to facilitate the operation. The aneurism needle is now passed from the outside, care being taken to keep the needle in close contact with the artery, and thus avoid the risk of injuring the jugular vein, or including the vagus nerve. Before the ligature is secured, it should be ascertained that nothing but the artery is included iu it. _ To tie the Common Carotid below the Omo-hyoid. The patient should be placed in the same situation as before. An incision about three inches in length is to be made parallel to the inner edge of the Sterno-mastoid, commencing on a level with the cricoid cartilage. The inner border of the Sterno-mastoid having been exposed, the sterno-mastoid artery and a large vein, the middle thyroid, will be seen, and must be carefully avoided ; the Sterno-mastoid is to be turned outwards, and the Sterno-hyoid and thyroid muscles inwards. The deep fascia must now be divided below the Omo-hyoid muscle, and the sheath having been exposed, must be opened, care being taken to avoid the descendens noni, which here runs on the inner or tracheal side. The jugular vein and vagus nerve being then pressed to the outer side, the needle must be passed around the artery, from without inwards, great care being taken to avoid the inferior thyroid artery, the recurrent laryngeal and sympathetic nerves, which he behind it. j c j r i EXTERNAL CAROTID. 319 External Carotid Artery. The external carotid artery (Fig. 189), arises opposite the upper border of the thyroid cartilage, and taking a slightly curved course, ascends upwards and for- wards, and then inclines backAvards, to the space betAveen the neck of the condyle of the lower jaw and the meatus auditorius, where it divides into the temporal and internal maxillary arteries. It rapidly diminishes in size as it ascends the neck, owing t;o the number and large size of the branches given off from it. In the child, it is somewhat smaller than the internal carotid; but in the adult, the two vessels are of nearly equal size. At its commencement, this artery is more superficial, and placed nearer the middle line than the internal carotid, and is con- tained in the triangular space bounded by the Sterno-mastoid behind, the Omo- hyoid below, and the posterior belly of the Digastric and Stylo-hyoid above; it is covered by the skin, Platysma, deep fascia, and anterior margin of the Sterno- mastoid, crossed by the hypoglossal nerve, and by the lingual and facial veins ; it is afterwards crossed by the Digastric and Stylo-hyoid muscles, and higher up passes deeply into the substance of the parotid gland, where it lies beneath the facial nerve, and by the junction of the temporal and internal maxillary veins. Internally, are the hyoid bone, the Avail of the pharynx, and the ramus of the jaw, from Avhich it is separated by a portion of the parotid gland. Behind it, near its origin, is the superior laryngeal nerve ; and, higher up, it is separated from the internal carotid by the Stylo-glossus and Stylo-pharyngeus muscles, the glosso-pharyngeal nerve, and part of the parotid gland. Plan of the Relations of the External Carotid. In front. Behind. Integument Platysma. ^—-^ Superior laryngeal nerve. Superficial and deep fasciae. / X Stylo-glossus Hypoglossal nerve. / External \ Stylo-pharyngeus. Lingual and facial veins. 1 Oarotid. J (llosso-pharyngeal nerve. Digastric and Stylo-hyoid muscles. \^ y Parotid gland. Facial nerve and parotid gland. Temporal and maxillary veins. Internally. Hyoid bone. Pharynx. Parotid gland. Ramus of jaw. Surgical Anatomy. The application of a ligature to the external carotid may be required in cases of wounds of this vessel, or of its branches when these cannot be tied; this, how- ever, is an operation very rarely performed, ligature of the common carotid being prefer- able, on account of the number of branches given off from the external. To tie this vessel near its origin, below the point where it is crossed by the Digastric, an incision about three inches in length should be made along the margin of the Sterno-mastoid, from the angle of the jaw to the cricoid cartilage, as in the operation for tying the common carotid. To tie the vessel above the Digastric, between it and the parotid gland, an incision should be made from the lobe of the ear to the great cornua of the os hyoides, dividing successively the skin, Platysma, and fascia. By separating the posterior belly of the Digastric and Stylo-hyoid muscles, which are seen at the lower part of the wound, from the parotid gland, the vessel will be exposed, and a ligature may be applied to it. Branches. The external carotid artery gives off eight branches, which, for convenience of description, may be divided into four sets. (See Fig. 190, Plan of the Branches.) Anterior. Posterior. Ascending. Terminal Superior thyroid. Occipital. Ascending pha- Temporal. Lingual. Posterior auricular. ryngeal. Internal maxillary. Facial. The student is here reminded that many variations are met with in the number, 320 ARTERIES. origin, and course of these branches in different subjects; but the above arrange- ment is that which is found in the great majority of cases. The Superior Thyroid Artery (Figs. 189 and 194) is the first branch given off from the external carotid, being derived from that vessel just beloAV the greater cornu of the hyoid bone. At its commencement, it is quite superficial, beino* covered by the integuments, fasciae, and Platysma, and is contained in the triangu- lar space bounded by the Sterno-mastoid, Digastric, and Omo-hyoid muscles. After ascending upAvards and inAvards for a short distance, it curves downwards and forAvards in an arched and tortuous manner to the upper part of the thyroid gland, passing beneath the Omo-hyoid, Sterno-hyoid, and Sterno-thyroid muscles ; and dis- tributes numerous branches to its anterior surface, anastomosing with its felloAv of the opposite side, and Avith the inferior thyroid arteries. Besides the arteries dis- tributed to the muscles and substance of the gland, its branches are the folloAving. Hyoid. _ _ .y.„ Superficial descending branch. _^V*/rt"'Vv* Superior laryngeal. fa^^^f?!^ Crico-thyroid. The Hyoid is a small branch which runs along the lower border of the os hy- oides, beneath, the Thyro-hyoid muscle ; and, after supplying the muscles connected to that bone, forms an arch, by anastomosing Avith the vessel of the opposite side. * The Superficial Descending Branch runs downwards and outAvards across the sheath of the common carotid artery, and supplies the Sterno-mastoid and neigh- boring vessels and integument. It is of importance that the situation of this vessel be remembered, in the operation for tying the common carotid artery. The Superior Laryngeal, larger than either of the preceding, accompanies the superior laryngeal nerve, beneath the Thyro-hyoid muscle ; it pierces the thyro- hyoidean membrane, and supplies the muscles, mucous membrane, and glands of the larynx and epiglottis, anastomosing with the branch from the opposite side. The Crico-thyroid (Inferior laryngeal) is a small branch, which runs trans- versely across the crico-thyroid membrane, communicating Avith the artery of the opposite side. The position of this vessel should be remembered, as it may prove the source of troublesome hemorrhage during the operation of laryngotomy. _ Surgical Anatomy. The superior thyroid, or some of its branches, are occasionally divided in cases of cut throat, giving rise to considerable hemorrhage. In such cases, the artery ^should be secured, the wound being enlarged for that purpose, if necessary. The operation may be easily performed, the position of the artery being very superficial, and the only structures of importance covering it being a few small veins. The operation of tying the superior thyroid artery, in bronchocele, has been performed in numerous instances, with partial or temporary success. When, however, the collateral circulation between this vessel with the artery of the opposite side, and with the inferior thyroid, is completely re-established, the tumor usually regains its former size. _ The Lingual Artery (Fig. 194) arises from the external carotid between the supe- rior thyroid and facial; it runs obliquely upwards and inwards to the greater cornu of the hyoid bone, then passes horizontally forwards parallel with the great cornu, and, ascending perpendicularly to the under surface of the tongue, turns forwards on its under surface as far as the tip of that organ, under the name of the ranine artery. Relations. Its first, or oblique portion, is superficial, being contained in the tri- angular intermuscular space already described, resting upon the Middle constrictor muscle of the pharynx, and covered in by the Platysma and fascia of the neck. Its second, or horizontal portion, also lies upon the middle constrictor, being covered at first by the tendon of the Digastric, and the Stylo-hyoid muscle, and afterwards by the Hyo-glossus, the latter muscle separating it from the hypoglossal nerve. Its third, or ascending portion, lies between the Hyo-glossus arid Genio-hyo-glossus muscles. The fourth, or terminal part, under the name of the ranine, runs along the under surface of the tongue to its tip; it is very superficial, being covered only LINGUAL; FACIAL. 321 by the mucous membrane, and rests on the Lingualis on the outer side of the Genio-hyo-glossus. The hypoglossal nerve lies nearly parallel Avith the lingual artery, separated from it, in the second part of its course, by the Hyo-glossus muscle. The branches of the lingual artery are the Hyoid. Sublingual. Dorsalis Linguae. Ranine. The Hyoid branch runs along the upper border of the hyoid bone, supplying the muscles attached to it, and anastomosing Avith its felloAv of the, opposite side. The Dorsalis Linguec (Fig. 194) arises from the lingual artery beneath the Hyo- glossus muscle; ascending to the dorsum of the tongue, it supplies its mucous membrane, the tonsil, soft palate, and epiglottis; anastomosing with its felloAv from the opposite side. The Sublingual, a branch of bifurcation of the lingual artery, arises at the ante- rior margin of the Hyo-glossus muscle, and running forwards and outAvards beneath the Mylo-hyoid to the sublingual gland, supplies its substance, giving branches to the Mylo-hyoid and neighboring muscles, the mucous membrane of the mouth and gums. The Ranine may be regarded as the continuation of the lingual artery ; it runs along the under surface of the tongue, resting on the Lingualis, and covered by the mucous membrane of the mouth ; it lies on the outer side of the Genio-hyo-glossus, and is covered in by the Hyo-glossus and Stylo-glossus, accompanied by the gusta- tory nerve. On arriving at the tip of the tongue, it anastomoses with the artery of the opposite side. These vessels in the mouth are placed one on each side of the fraenum. Surgical Anatomy. The lingual artery may be divided near its origin in cases of cut throat, a complication that not unfrequently happens in this class of wounds, or severe hemorrhage which cannot be restrained by ordinary means may ensue from a wound, or deep ulcer of the tongue. In the former case, the primary wound may be enlarged if necessary, and the bleed- ing vessel at once secured. In the latter case, it has been suggested that the lingual artery should be tied near its origin. If the student, however, will observe the depth at which this vessel is placed from the surface, the number of important parts which surround it on every side, and its occasional irregularity of origin, the great difficulty of such an operation will be apparent; under such circumstances, it is more advisable that the external or common caro- tid should be tied. Troublesome hemorrhage may occur in the division of the fraenum in children, if the ranine artery, which lies on each side of it, is cut through. The student should remember that the operation is always to be performed with a pair of blunt-pointed scissors, which should be so held as to divide the part in the direction downwards and backwards; the ranine artery and veins are then avoided. ' The Facial Artery (Fig. 191) arises a little above the lingual, and ascends obliquely forwards and upwards, beneath the body of the lower jaAv, to'the sub- maxillary gland, in Avhich it is imbedded; this may be called the cervical part of the artery. It then curves upwards over the body of the jaw at the anterior infe- rior angle of the Masseter muscle, ascends forAvards and upwards across the cheek to the angle of the mouth, passes up along the side of the nose, and terminates at the inner canthus of the eye, under the name of the angular artery. This vessel, both in the neck, and on the face, is remarkably tortuous; in the former situation, to accommodate itself to the movements of the pharynx in deglutition; and in the latter, to the movements of the jaw, and of the lips and cheeks. -Relations. In the neck its origin is superficial, being covered by the integument, Platysma, and fascia; it then passes beneath the Digastric and Stylo-hyoid mus- cles, and the submaxillary gland. On the face, where passing over the body of the lower jaw, it is comparatively superficial, being covered by the Platysma. In this situation its pulsation may be distinctly felt, and compression of the vessel effec- tually made against the bone. In its course over the face, it is covered by the integument, the fat of the cheek, and, near the angles of the mouth, by the Pla- tysma and Zygomatic muscles. Tt rests on the Buccinator, the Levator anguli oris, and theLeA'ator labii superioris alseque nasi. It is accompanied by the facial 23 322 ARTERIES. vein throughout its entire course; the vein is not tortuous like the artery, and, on the face, is separated from that vessel by a considerable interval. The branches of the facial nerve cross this vessel, and the infraorbital nerve lies beneath it. The branches of this vessel may be divided into two sets, those given off beloAv the jaiv (cervical), and those on the face (facial). Cervical Branches. Inferior or Ascending Palatine. Tonsillitic. Submaxillary. Submental. Facial Branches. Muscular. Inferior Labial. Inferior Coronary. Superior Coronary. Lateralis Nasi. Angular. Fig. 191.—The Arteries of the Face and Scalp. The Inferior or Ascending Palatine (Fig. 194) ascends between the Stylo-glossus and Stylo-pharyngeus to the outer side of the pharynx. After supplying these muscles, the tonsil, and Eustachian tube, it divides near the Levator palati into tAvo branches: one follows the course of the Tensor palati, supplies the soft palate andthe palatine glands; the other passes to the tonsil, which it supplies,, anasto- mosing with the tonsillitic artery. These vessels inosculate with the posteripr palatine branch of the internal maxillary artery. The Tonsillitic branch (Fig. 194) passes up along the side of the pharynx, and, perforating the Superior constrictor, ramifies in the substance of the tonsil and root of the tongue. FACIAL. 323 The Submaxillary consists of three or four large branches, Avhich supply the submaxillary gland, some being prolonged to the neighboring muscles, lymphatic glands, and integument. The Submental, the largest of the cervical branches, is given off from the facial artery just as that vessel quits the submaxillary gland ; it runs forAvards upon the Mylo-hyoid muscle, just beloAv the body of the jaw, and beneath the Digastric ; after supplying the muscles attached to the jaw, and anastomosing Avith the sub- lingual artery, it arrives at the symphysis of the chin, where it divides into a superficial and a deep branch ; the former turns round the chin, and passing be- tAveen the integument and Depressor labii inferioris, supplies both, and anastomoses with the inferior labial. The deep branch passes between that muscle and the bone, and supplies the lip, anastomosing Avith the inferior labial and mental arteries. The muscular branches are distributed to the Internal pterygoid, Masseter, and Buccinator. The Inferior Labial passes beneath the Depressor anguli oris, to supply the muscles and integument of the lower lip, anastomosing with the inferior coronary and submental branches of the facial, and with the mental branch of the inferior dental artery. The Inferior Coronary is derived from the facial artery near the angle of the mouth; it passes upwards and inwards beneath the Depressor anguli oris, and, penetrating the Orbicularis muscle, runs in a tortuous course along the edge of the lower lip betAveen this muscle and the mucous membrane, inosculating Avith the artery of the opposite side. This artery supplies the labial glands, the mucous membrane, and muscles of the lower lip : and anastomoses with the inferior labial, and mental branch of the inferior dental artery. The Superior Coronary is larger and more tortuous in its course than the pre- ceding. It follows the same course along the edge of the upper lip, lying between the mucous membrane and the Orbicularis, and anastomoses with the artery of the opposite side. It supplies the textures of the upper lip, and gives off in its course two or three vessels Avhich ascend to the nose. One, named the artery of the sep- tum, ramifies on the septum of the nares as far as the point of the nose ; another supplies the ala of the nose. The Lateralis Nasi is derived from the facial, as this vessel is ascending along the side of the nose; it supplies the ala and dorsum of the nose, anastomosing with its fellow, the nasal branch of the ophthalmic, the artery of the septum, and the infraorbital. The Angular Artery is the termination of the trunk of the facial; it ascends to the inner angle of the orbit, accompanied by a large vein, the angular ; it distri- butes some branches on the cheek which anastomose with the infraorbital, and after supplying the lachrymal sac, and Orbicularis muscle, terminates by anasto- mosing with the nasal branch of the ophthalmic artery. The anastomoses of the facial artery are very numerous, not only Avith the vessel of the opposite side, but with other vessels from different sources; viz., with the sublingual branch of the lingual, Avith the mental branch of the inferior dental as it emerges from the dental foramen, Avith the ascending pharyngeal and posterior palatine, and Avith the ophthalmic, a branch of the internal carotid; it also inoscu- lates with the transverse facial, and Avith the infraorbital. Peculiarities. The facial artery not unfrequently arises by a common trunk with the lin- gual. This vessel also is subject to some variations in its size, and in the extent to which it supplies the face. It occasionally terminates as the submental, and not unfrequently supplies the face only as high as the angle of the mouth or nose. The deficiency is then supplied by enlargement of one of the neighboring arteries. Surgical Anatomy. The passage of the facial artery over the body of the jaw would ap- pear to afford a favorable position for the application of pressure in cases of hemorrhage from the lips, the result either of an accidental wound, or from an operation ; but its ap- plication is useless, on account of the free communication of this vessel with its fellow, and 324 ARTERIES. with numerous braucbes from different sources. In a wound involving the lip, it is better to seize the part between the fingers and evert it, when the bleeding vessel may be at once secured with a tenaculum. In order to prevent hemorrhage in cases of excision, or in the removal of diseased growths from the part, the lip should be compressed on each side be- tween the finger and thumb, whilst the surgeon excises the diseased part. In order to stop hemorrhage where the lip has been divided in an operation, it is necessary in uniting the edges of the wound, to pass the sutures through the cut edges, almost as deep as its mucous surface ; by these means, not only are the cut surfaces more neatly adapted to each other but the possibility of hemorrhage is prevented by including in the suture the divided artery. If the suture is, on the contrary, passed through merely the cutaneous portion of the wound hemorrhage occurs into the cavity of the mouth. The student should, lastly, observe the relation of the angular artery to the lachrymal sac, and it will be seen that, as the vessel passes up along the inner margin of the orbit, it ascends on its nasal side. In operating for fistula lacrymalis, the sac should always be opened on its outer side, in order that this vessel should be avoided. The Occipital Artery arises from the posterior part of the external carotid, opposite the facial, near the lower margin of the Digastric muscle. At its origin, it is covered by the posterior belly of the Digastric and Stylo-hyoid muscles, and part of the parotid gland, the hypoglossal nerve Avinding around it from behind forAvards; higher up, it passes across the internal carotid artery, the internal jugular vein, and the pneumogastric and spinal accessory nerves : it then ascends to the interval betAveen the tranverse process of the atlas and the mastoid process of the temporal bone, passes horizontally backAvards, grooving the surface of the latter bone, being covered by the Sterno-mastoid, Splenius, Digastric, and Trachelo- mastoid muscles, resting upon the Complexus, Superior oblique, and Rectus pos- ticus major muscles ; it then passes vertically upAvards, piercing the cranial attach- ment of the Trapezius, and ascends in a tortuous course on the occiput as high as the vertex, where it divides into numerous branches. The branches given off from this vessel are, Muscular. Inferior meningeal. Auricular. Arteria princeps cervicis. The Muscular Branches supply the Digastric, Stylo-hyoid, Sterno-mastoid, Splenius, and Trachelo-mastoid muscles. The branch distributed to the Sterno- mastoid is of a large size. The Auricular Branch supplies the back part of the concha. The Meningeal Branch ascends with the internal jugular vein, and enters the skull through the foramen lacerum posterius, to supply the dura mater in the pos- terior fossa. The Arteria Princeps Cervicis (Fig. 194) is a large vessel which descends along the back part of the neck, and divides into a superficial and deep branch. The former runs beneath the Splenius, giving off branches Avhich perforate that muscle to supply the Trapezius, anastomosing Avith the superficial cervical artery ; the latter passes beneath the Complexus, between it and the Semispinalis colli, and anastomoses with the vertebral, and deep cervical branch of the superior inter- costal. The anastomosis between this vessel and the profunda cervicis serves mainly to establish the collateral circulation after ligature of the carotid or sub- clavian artery. The cranial branches of the occipital artery are distributed upon the occiput; they are very tortuous, and lie between the" integument and Occipito-frontalis, anastomosing with their fellows of the opposite side, the posterior auricular, and temporal arteries. They supply the posterior part of the Occipito-frontalis muscle, the integument, pericranium, and one or two branches occasionally pass through , the parietal or mastoid foramina, to supply the dura mater. The Posterior Auricular Artery (Fig. 191) is a small vessel, Avhich arises from the external carotid, above the Digastric and Stylo-hyoid muscles, opposite the apex of the styloid process. It ascends, under cover of the parotid gland, to the groove between the cartilage of the ear and the mastoid process, immediately POSTERIOR ARRICULAR; PHARYNGEAL; TEMPORAL. 325 above which it divides into two branches, an anterior, which passes forAvards to anastomose with the posterior division of the temporal, and a posterior, which com- municates with the occipital. Just before arriving at the mastoid process, this artery is crossed by the portio dura, and has beneath it the spinal accessory nerve. Besides several small branches to the Digastric, Stylo-hyoid, and Sterno-mastoid muscles, and to the parotid gland, this vessel gives off two branches. Stylo-mastoid. Auricular. The Stylo-mastoid Branch enters the stylo-mastoid foramen, and supplies the tympanum, mastoid cells, and semicircular canals. In the young subject, a branch from this vessel forms, Avith the tympanic branch from the internal maxillary, a delicate vascular circle, Avhich surrounds the auditory meatus, and from which delicate vessels ramify on the membrana tympani. The Auricular■_ Branch is distributed to the posterior part of the cartilage of the ear, upon which it minutely ramifies, some branches curving round its margin, others perforating the fibro-cartilage, to supply its anterior surface. The Ascending Pharyngeal Artery (Fig. 194), the smallest branch of the external carotid, is a long slender vessel, deeply seated in the neck, beneath the other branches of the external carotid and Stylo-pharyngeus muscle. It arises from the posterior part of the external carotid, and ascends the neck to the under surface of the base of the skull. It lies upon the Rectus capitis anticus major, between the internal carotid and the outer wall of the pharynx. Its branches may be subdivided into three sets: 1. Those directed outAvards to supply muscles and nerves. 2. Those directed inAvards to the pharynx. 3. Meningeal branches. External. Pharyngeal. Meningeal. The External Branches are numerous small vessels, Avhich supply the Recti antici muscles, the sympathetic, lingual, and pneumogastric nerves, and the lymphatic glands of the neck, anastomosing Avith the ascending ce'rvical branch of the sub- clavian artery. The Pharyngeal Branches are three or four in number. Tavo of these descend to supply the Middle and Inferior constrictors and the Stylo-pharyngeus, ramifying in their substance and in the mucous membrane lining them. The largest of the pharyngeal branches passes inAvards, running upon the Superior constrictor, and sending ramifications to the soft palate, Eustachian tube, and tonsil, taking the place of the ascending palatine branch of the facial artery, when that vessel is of small size. The Meningeal Branches consist of several small vessels, which pass through foramina in the base of the skull, to supply the dura mater. One, the posterior meningeal, enters the cranium through the foramen lacerum posterius Avith the internal jugular Arein. A second passes through the foramen lacerum basis cranii; and occasionally a third through the anterior condyloid foramen. They are all distributed to the dura mater. The Temporal Artery (Fig. 191), tfie smaller of the tAvo terminal branches of the external carotid, appears, from its direction, to be the continuation of that Aressel. It commences in the substance of the parotid gland, in the interspace betAveen the neck of the condyle of the loAver jaw and the external meatus; crossing over the root of the zygoma, immediately beneath the integument, it divides about two inches above the zygomatic arch into tAvo branches, an anterior and a posterior. The Anterior Temporal inclines forAvards over the forehead, supplying the mus- cles, integument, and pericranium in this region, and anastomoses with the supra- orbital and frontal arteries, its branches being directed from before backwards. The Posterior Temporal, larger than the anterior, curves upAvards and back- Avards along the side of the head, lying above the temporal fascia, and inosculates Avith its felloAv of the opposite side, and Avith the posterior auricular and occipital arteries. 326 ARTERIES. The temporal artery, as it crosses the zygoma, is covered by the Attrahens aurem muscle, and by a dense fascia given ofi" from the parotid gland; it is also usually crossed by one or two veins, and accompanied by branches of the facial nerve. Besides some tAvigs to the parotid gland, the articulation of the jaw, and to the Masseter muscle, its branches are the Transverse facial. Middle temporal. Anterior auricular. The Transverse Facial is given off from the temporal before that vessel quits the parotid gland; running forwards through its substance, it passes transversely across the face, betAveen Steno's duct and the loAver border of the zygoma, and divides on the side of the face into numerous branches, which supply 'the parotid gland the Masseter muscle, and the integument, anastomosing Avith the facial and infra- orbital arteries. This vessel rests on the Masseter, and is accompanied by one or tAvo branches of the facial nerve. The Middle Temporal Artery arises immediately above the zygomatic arch, and perforating the temporal fascia, supplies the Temporal muscle, anastomosing'with the deep temporal branches of the internal maxillary. It occasionally gives off an orbital branch, which runs along the upper border of the zygoma, between the two layers of the temporal fascia, to the outer angle of the orbit; it supplies the Orbicularis, and anastomoses with the lachrymal and palpebral branches of the ophthalmic artery. _ The Anterior Auricular Branches are distributed to the anterior portion of the pinna, the lobule, and part of the external meatus, anastomosing with branches of the posterior auricular. Surgical Anatomy. It occasionally happens that the surgeon is called upon to perform the operation of artenotomy upon this vessel in cases of inflammation of the pye or brain Under these circumstances, the anterior branch is the one usually selected. If the student will consider the relations of the trunk of this vessel with the surrounding structures as it crosses the zygomatic arch, he will observe that it is covered by a thick and dense fascia crossed by one or two veins, and accompanied by branches of the facial and temporo-auri- cular nerves. Bleeding should not be performed in this situation, as considerable difficulty may arise from the dense fascia covering this vessel preventing a free flow of blood, and considerable pressure is requisite afterwards to repress it. Asrain, a varicose aneurism may be formed by the accidental opening of one of the veins covering it; or severe neuralgic pain may arise from the operation implicating one of the nervous filaments which accompany the artery. * J The anterior branch is, on the contrary, subcutaneous, is a large vessel, and as readily compressed as any other portion of the artery; it should consequently always be selected for the operation. i j j The Internal Maxillary, the larger of the two terminal branches of the external carotid, passes inwards, at right angles from that vessel, behind the neck ol the lower jaw, to supply the deep structures of the face. At its origin, it is imbedded in the substance of the parotid gland, being on a level with the lower extremity of the lobe of the ear. In the first part of its course (maxillary portion), the artery passes horizontally fonvards and inwards, between the ramus of the jaw, and"the internal lateral ligament lhe artery here lies parallel with the auricular nerve; it crosses the inferior dental nerve, and lies beneath the narrow portion of the External ptery- goid muscle. l J In the second part of its course (pterygoid portion), it ascends obliquely forwards and upwards upon the outer surface of .the External pterygoid muscle. In the third part of its course (spheno-maxillary portion), it approaches the superior maxillary bone, crosses the interval between the two heads of the Exter- nal pterygoid and enters the spheno-maxillary fossa, where it lies in relation with Meckel s ganglion, and gives off its terminal branches. INTERNAL MAXILLARY. 327 Peculiarities. Occasionally, this artery passes between the two Pterygoid muscles. The vessel in this case passes forwards to the interval between the two heads of the External pterygoid, in order to reach the maxillary bone. Sometimes, the vessel escapes from be- neath the External pterygoid by perforating the middle of this muscle. Fig. 192.—The Internal Maxillary Artery, and its Brandies. The branches of this vessel may be divided into three groups, corresponding with its three divisions. Branches from the Maxillary Portion. Tympanic. Small meningeal. Middle meningeal. Inferior dental. The Tympanic Branch passes upAvards behind the articulation of the loAArer jaw, enters the tympanum through the fissura Glaseri, supplies the Laxator tym- pani, and ramifies upon the membrana tympani, anastomosing with the stylo- mastoid and Vidian arteries. The Middle Meningeed is the largest of the branches Avhich supply the dura mater. It arises from the internal maxillary betAveen the internal lateral ligament and the neck of the jaAv, and ascends Arertically upAvards to the foramen spinosum in the spinous process of the sphenoid bone. On entering the cranium, it divides into tAvo branches, an anterior and a posterior. The anterior branch, the larger,. crosses the great ala of the sphenoid, and reaches the groove, or canal, in the an- 328 ARTERIES. terior inferior angle of the parietal bone ; it then divides into branches which spread out between the dura mater and internal surface of the cranium, some passing upAvards over the parietal bone as far as the vertex, and others backwards to the occipital bone. The posterior branch crosses the squamous portion of the temporal, and on the inner surface of the parietal bone divides into branches which supply the posterior part of the dura mater and cranium. The branches of this vessel are distributed to the dura mater, but chiefly to the bones : they anastomose with the arteries of the opposite side, and Avith the anterior and posterior meningeal. The middle meningeal, on entering the cranium, gives off the folloAving colla- teral branches: 1. Numerous small vessels to the ganglion of the fifth nerve, and to the dura mater in this situation. 2. A branch to the facial nerve, which enters the hiatus Fallopii, supplies the facial neiwe, and anastomoses with the stylo- mastoid branch of the occipital artery. 3. Orbital branches, Avhich pass through the sphenoidal fissure, or through separate canals in the great Aving of the sphe- noid, to anastomose with the lachrymal or other branches of the ophthalmic artery. 1. Temporal branches, Avhich pass through foramina in the great wing of the sphenoid, and anastomose in the temporal fossa with the deep temporal arteries. The Small Meningeal is sometimes derived from the preceding. It enters the skull through the foramen OArale, and supplies the Casserian ganglion and dura mater. Before entering the cranium, it gives off a branch to the nasal fossa and soft palate. The Inferior Dental descends with the dental nerve, to the foramen on the inner side of the ramus of the jaw. It runs along the dental canal in the sub- stance of the bone, accompanied by the nerve, and opposite the bicuspid tooth di- vides into twro branches, an incisor, Avhich is continued forAvards beneath the incisor teeth as far as the symphysis, Avhere it anastomoses Avith the artery of the opposite side ; the other, the mental, escapes Avith the nerve at the mental foramen, supplies the structures composing the chin, and anastomoses Avith the submental, inferior labial, and inferior coronary arteries. As the dental artery enters the foramen, it gives off a mylo-hyoid branch, which runs in the mylo-hyoid groove, and ramifies on the under surface of the Mylo-hyoid muscle. The dental and incisor arteries, during their course through the substance of the bone, give off a feAV tAvigs which are lost in the diploe, and a series of branches Avhich correspond in number to the roots of the teeth; these enter the minute apertures at the extremities of the fangs, and ascend to supply the pulp of the teeth. Branches of the Second, or Pterygoid Portion. Deep temporal. Masseteric. Pterygoid. Buccal. These branches are distributed, as their names imply, to the muscles in the maxillary region. The Deep Temporal Brandies, tAvo in number, anterior and posterior, each occupy that part of the temporal fossa indicated by its name. Ascending between the Temporal muscle and pericranium, they supply that muscle, and anastomose Avith the other temporal arteries; the anterior branch communicating with the lachrymal through small branches which perforate the malar bone. The Pterygoid Branches, irregular in their number and origin, supply the Pterygoid muscles. The Masseteric is a small branch which passes outAvards above the sigmoid notch of the lower jaw, to the deep surface of the Masseter. It supplies that muscle, and anastomoses Avith the masseteric branches of the facial and transverse facial arteries. The Buccal is a small branch which runs obliquely forwards between the Inter- INTERNAL MAXILLARY. 329 nal pterygoid, and the ramus of the jaw, to the outer surface of the Buccinator, to Avhich it is distributed, anastomosing with branches of the facial artery. Branches of the Third, or Spheno-maxillary Portion. Alveolar. Vidian. Infraorbital. Pterygo-palatine. Posterior or Descending Palatine. Nasal or Spheno-palatine. The Alveolar is given off from the internal maxillary by a common branch with the infraorbital, and just as the trunk of the vessel is passing into the spheno-maxillary fossa. Descending upon the tuberosity of the superior maxillary bone, it divides into numerous branches; one, the superior dental, larger than the rest, supplies the molar and bicuspid teeth; its branches entering the foramina in the alveolar process, some branches pierce the bone to supply the lining of the antrum, and others are continued forwards on the alveolar process to supply the gums. The Infraorbital appears, from its direction, to be the continuation of the trunk of the internal maxillary. It arises from that vessel by a common trunk Avith the preceding branch, and runs along the infraorbital canal with the superior maxillary nerve, emerging upon the face at the infraorbital foramen, beneath the Levator labii superioris. Whilst contained in the canal, it gives off branches which ascend into the orbit, and supply the Inferior rectus, and Inferior oblique muscles, and the lachrymal gland. Other branches descend through canals in the bone, to supply the mucous membrane of the antrum, and the front teeth of the upper jaAV. On the face, it supplies the lachrymal sac, and inner angle of the orbit, anasto- mosing with the facial and nasal branches of the ophthalmic arteries ; and other branches descend beneath the elevator of the upper lip, and anastomose Avith the transverse facial and buccal branches. The four remaining branches arise from that portion of the internal maxillary Avhich is contained in the spheno-maxillary fossa. The Descending Palatine passes down along the posterior palatine canal Avith the posterior palatine branches of Meckel's ganglion, and emerging from the posterior palatine foramen, runs forwards in a groove on the inner side of the alveolar bor- der of the hard palate, to be distributed to the gums, the mucous membrane of the hard palate, and palatine glands. Whilst it is contained in the palatine canal, it gives off branches, which descend in the accessory palatine canals to supply the soft palate, anastomosing with the ascending palatine artery; and anteriorly it ter- minates in a small vessel, which ascends in the anterior palatine canal, and anasto- moses with the artery of the septum, a branch of the spheno-palatine. The Vidian Branch passes backAvards along the Vidian canal Avith the Vidian nerve. It is distributed to the upper part of the pharynx and Eustachian tube, sending a small branch into the tympanum. The Pterygo-palatine is also a very small branch, Avhich passes backwards through the pterygo-palatine canal Avith the pharyngeal nerve, and is distributed to the upper part of the pharynx and Eustachian tube. The Nasal or Spheno-palatine passes through the spheno-palatine foramen into the cavity of the nose, at the back part of the superior meatus, and divides into two branches; one internal, the artery of the septum, passes obliquely doAvmvards and forwards along the septum nasi, supplies the mucous membrane, and anasto- moses in front with the ascending branch of the descending palatine. The external branches, tAvo or three in number, supply the mucous membrane covering the lateral wall of the nares, the antrum, and the ethmoid and sphenoid cells. Surgical Anatomy of the Triangles of the Neck. The student having studied the relative anatomy of the large arteries of the neck and their branches, and the relations they bear to the veins and nerves, should 330 SURGICAL ANATOMY. now examine these structures collectively, as they present themselves in certain regions of the neck, in each of which important operations are being constantly performed. For this purpose, the Sterno-mastoid, or any other muscles that have been di- vided in the dissection of these vessels, should be replaced in their normal position, the head should be supported by placing a block at the back of the neck, and the face turned to the side opposite to that which is being examined. The side of the neck presents a somewhat quadrilateral outline, limited, above by the lower border of the body of the jaAV, and an imaginary line, extending from the angle of the jaAv to the mastoid process; beloAv, by the prominent upper border of the clavicle; in front, by the median line of the neck ; behind, by the anterior margin of the Trapezius muscle. This space is subdivided into tAvo large triangles by the Sterno-mastoid muscle, which passes obliquely across the neck, from the sternum and clavicle, below, to the mastoid process, above. The anterior margin of this muscle forms a prominent ridge beneath the skin, Avhich serves as a guide to the surgeon in the operation for applying a ligature to the common carotid artery, or in oesophagotomy. The triangular space in front of this muscle is called the anterior triangle, and that behind it, the posterior triangle. Anterior Triangular Space. The anterior triangle is limited, in front, by a line extending from the chin to the sternum; behind, by the anterior margin of the Sterno-mastoid; its base, directed upwards, is formed by the lower border of the body of the jaw, and a line extending from the angle of the jaw to the mastoid process; its apex is formed beloAv by the sternum. This space is covered in by the integument, superficial fascia, Platysma, deep fascia, crossed by branches of the facial and superficial cer- vical nerves; and subdivided into three smaller triangles by the Digastric muscle, above, and the anterior belly of the Omo-hyoid, beloAV. These are named, from beloAv upwards, the inferior carotid triangle, the superior carotid triangle, and the submaxillary triangle. Each of these spaces must noAv be separately examined. The Inferior Carotid Triangle is limited, in front, by the median line of the neck ; behind, by the anterior margin of the Sterno-mastoid; above, by the ante- rior belly of the Omo-hyoid; and it is covered in by the integument, Platysma, superficial and deep fasciae; ramifying betAveen which is seen the cutaneous descending branch of the superficial cervical nerve. Beneath these superficial structures, are the Sterno-hyoid and Sterno-thyroid muscles, which, together with the anterior margin of the Sterno-mastoid, conceal the lower part of the com- mon carotid _ artery. This vessel is inclosed within its sheath, together with the internal jugular vein and pneumogastric nerve; the vein lying on the outer side of the artery on the right side of the neck, but overlapping it, or passing directly across it on the left side; the nerve lying between the artery and vein, on a plane posterior to both. In front of the sheath are a few filaments descending from the loop of communication between the descendens and communicans noni; behind the sheath is seen the inferior thyroid artery, the recurrent laryngeal and sympathetic nerves; and on its inner side, the trachea, the thyroid gland, much more prominent in the female than in the male, and the lower part of the larynx. In the upper part of this space, the common carotid artery may be tied below the Omo-hyoid muscle. The Superior Carotid Triangle is bounded, behind, by the Sterno-mastoid; below, by the anterior belly of the Omo-hyoid; and above, by the posterior belly of the Digastric muscle. Its floor is formed by parts of the Thyro-hyoid, Hyo- glossus and the Inferior and Middle constrictor muscles of the pharynx; and it is covered in by the integument, Platysma, superficial and deep fascia; ramifying betAveen which, are branches of the facial and superficial cervical nerves. This space contains the upper part of the common carotid artery, which bifurcates opposite the upper border of the thyroid cartilage into the external and internal OF THE TRIANGLES OF THE NECK. 331 carotid. These vessels are concealed from vieAv by the anterior margin of the Sterno-mastoid muscle, which overlaps them. The external and internal carotids lie side by side, the external being the most anterior of the tAvo. The folloAving branches of the external carotid are also met Avith in this space : the superior thyroid, which runs forAvards and downwards ; the lingual, which passes directly forwards ; the facial, fonvards and upwards ; the occipital is directed backwards; and the ascending pharyngeal runs directly upAvards on the inner side of the internal carotid. The veins met with are, the internal jugular, Avhich lies on the outer side of the common and internal carotid vessels, and veins corresponding to the above-mentioned branches of the external carotid, viz., the superior and middle thyroid, the lingual, facial, ascending pharyngeal, and sometimes the occipital; all of which accompany their corresponding arteries, and terminate in the internal jugular. In front of the sheath of the common carotid is the descendens noni, the hypoglossal, from which it is derived, crossing both carotids above, curving around the occipital artery at its origin. Within the sheath, betAveen the artery and vein, and behind both, is the pneumogastric nerve ; behind the sheath, the sympathetic. On the outer side of the vessels the spinal accessory nerve runs for a short distance before it pierces the Sterno-mastoid muscle ; and on the inner side of the internal carotid, just beloAV the hyoid bone, may be seen the superior laryngeal nerve; and still more interiorly, the external laryngeal nerve. The upper part of the larynx and the pharynx are also found in the front part of this space. The Submaxillary Triangle corresponds to that part of the neck immediately beneath the body of the jaAv. It is bounded above, by the lower border of the body of the jaAV, the parotid gland, and mastoid process; behind, by the posterior belly of the Digastric and* Stylo-hyoid muscles ; in front, by the middle line of the neck. The floor of this space is formed by the anterior belly of the Digastric, and Mylo-hyoid, and Hyo-glossus muscles; and it is covered in by the integument, Platysma, superficial and deep fasciae ; ramifying betAveen Avhich, are branches of the facial and ascending filaments of the superficial cervical nerve. This space contains in front, the submaxillary gland, imbedded in Avhich are the facial artery and vein, and their glandular branches ; beneath this gland, on the sur- face of the Mylo-hyoid muscle, are the submental artery, and the mylo-hyoid artery and nerve. The posterior part of this space is separated from the anterior part, by the stylo-maxillary ligament; it contains the external carotid artery, ascending deeply in the substance of the parotid gland ; this vessel here lies in front of and superficial to the internal carotid, being crossed by the facial nerve, and giving off in its course the posterior auricular, temporal, and internal maxillary branches ; more deeply seated is the internal carotid, the internal jugular vein, and the pneumogastric nerve, separated from the external carotid by the Stylo-glossus and Stylo-pharyngeus muscles, and the glosso-pharyngeal nerve. Posterior Triangular Space. The posterior triangular space is bounded in front by the Sterno-mastoid muscle, behind, by the anterior margin of the Trapezius ; its base corresponds to the upper border of the clavicle, its apex to the occiput. This space is crossed about an inch above the clavicle by the posterior belly of the Omo-hyoid, Avhich divides it unequally into tAvo, an upper or occipital, and a loAver or subclavian. The Occipital, the larger of the tAvo posterior triangles, is bounded in front by the Sterno-mastoid; behind by the Trapezius; beloAV by the Omo-hyoid. Its floor is formed from above downwards by the Splenius, Levator anguli scapulae, and the Middle and Posterior scaleni muscles. It is covered in by the integu- ment, the Platysma beloAv, the superficial and deep fascial, and crossed, above, by the ascending branches of the cervical plexus ; the spinal accessory nerve is directed obliquely across the space from the Sterno-mastoid, Avhich it pierces, to the under surface of the Trapezius; beloAv, it is crossed by the ascending branches of the same plexus and transversalis colli artery and vein. A chain of lymphatic 332 ARTERIES. glands is also found running along the posterior border of the Sterno-mastoid from the mastoid process to the root of the neck. The Subclavian, the smaller of the tAvo posterior triangles, is bounded above by the posterior belly of the Omo-hyoid; below, by the clavicle; its base directed forwards, being formed by the Sterno-mastoid. * The size of this space varies according to the extent of attachment of the clavicular portion of the Sterno- mastoid and Trapezius muscles, and also according to the height at Avhich the Omo- hyoid crosses the neck above the clavicle. The height also of this space varies much, according to the position of the arm, being much diminished on raisin«• the limb, on account of the ascent of the clavicle, and increased on draAving the arm downwards, Avhen this bone is consequently depressed. This space is covered in by the integument, the superficial and deep fasciae, and crossed by the descending branchesof the cervical plexus. Passing across it, just above the level of the clavicle, is the third portion of the Subclavian artery, Avhich curves outAvards and downAvards from the outer margin of the Scalenus anticus, across the first rib, to the axilla. Sometimes this vessel rises as high as an inch and a half above the clavicle, or to any point intermediate between this and its usual level. Occasion- ally it passes in front of the Scalenus anticus, or pierces the fibres of this muscle. The subclavian vein lies beneath the clavicle, and is usually not seen in this space; but it occasionally rises as high up as the artery, and has even been seen to pass with that vessel behind the Scalenus anticus. The brachial plexus of nerves lies above the artery, and in close contact Avith it. Passing transversely across the clavicular margin of the space, are the suprascapular vessels, and traversing its upper angle in the same direction, the transverse cervical vessels. The external jugular vein descends vertically downwards behind the posterior border of the Sterno-mastoid, to terminate in the subclavian; it receives the trans- verse cervical and suprascapular veins, which occasionally form a plexus in front of the artery, and a small vein which crosses the clavicle from the cephalic. The small nerve to the Subclavius also crosses this space about its centre. Internal Carotid Artery. The internal carotid artery commences at the bifurcation of the common carotid, opposite the upper border of the thyroid cartilage, and ascends perpendicularly upAvards, m front of the transverse processes of the three upper cervical vertebrse. to the carotid foramen in the petrous portion of the temporal bone. After ascend- ing m it for a short distance, it passes forAvards and inwards through the carotid canal, and ascending a little by the side of the sella Turcica, curves upwards by the anterior clinoid process, where it pierces the dura mater, and divides into its terminal branches. This vessel supplies the anterior part of the brain, the eye, and its appendages. Its size m the adult is equal to that of the external carotid ; in the child it is larger than that vessel. It is remarkable for the number of curvatures that it presents in different parts of its course. In its cervical portion it occasionally presents one or two flexures near the base of the skull, whilst throuo-h the rest of its extent it describes a double curvature, which resembles the Italic letter / placed horizontally ^. These curvatures most probably diminish the velocity of tne current of blood, by increasing the extent of surface over which it moves, and adding to the amount of impediment produced by friction. In considering the course and relations of this vessel, it may be conveniently divided into four por- tions, a cervical, petrous, cavernous, and cerebral. Cervical Portion. This portion of the internal carotid at its commencement is Aery superficial being contained in the superior carotid triangle, on the same level but behind the external carotid, overlapped by the Sterno-mastoid, and covered by the Platysma, deep fascia, and integument; it then passes beneath the parotid gland, being crossed by the hypoglossal nerve, the Digastric and Stylo- hyoid muscles, and the external carotid and occipital arteries. Higher up it is separated from the external carotid by the Stylo-glossus and Stylo-pharyngeus INTERNAL CAROTID. 333 muscles and the glosso-pharyngeal nerve. It is in relation, posteriorly, with the Rectus anticus major, the superior cervical ganglion of the sympathetic, and supe- rior laryngeal nerve; externally, with the internal jugular vein, and pneumogas- tric nerve; internally, with the pharynx, the tonsil, and the ascending pharyngeal artery. Fig. 194.—The Internal Carotid and Vertebral Arteries. Right Side. Petrous Portion. When the internal carotid artery enters the canal in the petrous portion of the temporal bone, it first ascends a short distance, then curves for- wards and inwards, and again ascends as it leaves the canal to enter the cavity of the skull. In this canal, the artery lies at first anterior to the tympanum, from which it is separated by a thin bony lamella, which is cribriform in the young sub- ject, and often absorbed in old age. It is separated from the bony wall of the 331 ARTERIES. carotid canal by a prolongation of dura mater, and is surrounded by filaments of the carotid plexus. Cavernous Portion. The external carotid artery, in this part of its course ascends by the side of the body of the sphenoid bone, being situated on the inner Avail of the cavernous sinus, in relation, externally, with the sixth nerve, and covered by the lining membrane of the sinus. The third, fourth, and ophthalmic nerves are placed on the outer Avail of the cavernous sinus, being separated from its cavity by the lining membrane. Cerebral Portion. On the inner side of the anterior clinoid process the internal carotid perforates the dura mater, and is received into a sheath of the arachnoid. This portion of the artery is on the outer side of the optic nerve; it lies at the inner extremity of the fissure of Sylvius, having the third nerve externally. Peculiarities. The length of the internal carotid varies according to the length of the neck, and also according to the point of bifurcation of the common carotid. Its origin some- times takes place from the arch of the aorta; this vessel, in such rare instances, was placed nearer the middle line of the neck than the external carotid, as far upwards as the larynx, when the latter vessel crossed the internal carotid. The course of the vessel, instead of being straight, may be very tortuous. A few instances are recorded in which this vessel may be altogether absent: in one of these the common carotid ascended the neck, and gave off the usual branches of the external carotid; the cranial portion of the vessel being replaced by two branches of the internal maxillary, which entered the skull through the foramen rotundum and ovale, and joined to form a single vessel. Surgical Anatomy. The cervical part of the internal carotid is sometimes wounded by a stab or gun-shot wound in the neck, or even occasionally by a stab from within the mouth, as when a person receives a thrust from the end of a parasol, or falls down with a tobacco-pipe in his mouth. In such cases a ligature should be applied to the common carotid. The branches given off from the internal carotid are :— From Petrous Portion . Tympanic. ( Arte'riae receptaculi. From Cavernous Portion< Anterior meningeal. ( Ophthalmic. f Anterior cerebral. From Cerebral Portion {lMd]e <*rebral. . _ )J ostenor communicating. C Anterior choroid. The Cervical Portion of the internal carotid gives off no branches. The Tympanic is a small branch which enters the cavity of the tympanum, through a minute foramen in the carotid canal, and anastomoses with the tympanic .branch of the internal maxillary, and stylo-mastoid arteries. The Arteria receptaculi are numerous small vessels, derived from the carotid artery in the cavernous sinus; they supply the pituitary body, the Casserian ganglion, and the Avails of the cavernous and inferior petrosal sinuses. One of these branches, distributed to the dura mater, is called the anterior meningeal; it anastomoses Avith the middle meningeal. The Ophthalmic Artery arises from the internal carotid, just as that vessel is emerging from the cavernous sinus, on the inner side of the anterior clinoid pro- cess, and enters the orbit through the optic foramen, below and on the outer side of the optic nerve. It then crosses above, and to the inner side of this nerve, to the inner wall of the orbit, and, passing horizontally forwards, beneath the lower border of the Superior oblique muscle, to the inner angle of the eye, divides into two terminal branches, the frontal and nasal. Branches. The branches of this vessel may be divided into an orbital group, which are distributed to the orbit and surrounding parts; and an ocular group, which supply the muscles and glpbe of the eye. OPHTHALMIC. 335 Fig. 105.—The Ophthalmic Artery and its Branches, the Roof of the Orbit having been removed. VrmZ Pa,lpt\'°l Tvontal | Snpi-tt Orbitai Anterior H&mnJd I'ozterior JEffimolda, I CaratiS* Ocular Group. Muscular." Anterior ciliary. Short ciliary. Long ciliary. Arteria centralis retinae. Orbital Group. Lachrymal. Supraorbital. Posterior ethmoidal. Anterior ethmoidal. Palpebral. Frontal. Nasal. The Lachrymal is the first, and one of the largest branches, derived from the ophthalmic, arising close to the optic foramen, and not unfrequently from that vessel before entering the orbit. It accompanies the lachrymal nerve along the upper border of the External rectus muscle, and is distributed to the lachrymal gland. Its terminal branches, escaping from the gland, are distributed to the upper eyelid and conjunctiva, anastomosing Avith the palpebral arteries. The lachrymal artery gives off ome or two ' malar branches; one of which passes through a foramen in the malar bone to reach the temporal fossa and anastomoses with the deep temporal arteries. The other appears on the cheek, and anastomoses with the transverse facial. A branch is also sent backAvards, through the sphe- noidal fissure, to the dura mater, which anastomoses with a branch of the middle meningeal artery. Peculiarities. The lachrymal artery is sometimes derived from one of the anterior branches of the middle meningeal artery. The Supraorbital artery, the largest branch of the ophthalmic, arises from that vessel above the optic nerve. Ascending so as to rise above all the muscles of the orbit, it passes forwards, with the frontal nerve, betAveen the periosteum and Levator palpebrae ; and, passing through the supraorbital foramen, divides into a superficial and deep branch, which supply the muscles and integument of the forehead and pericranium, anastomosing with the temporal, angular branch of the facial, and the artery of the opposite side. This artery in the orbit supplies the 336 ARTERIES. Superior rectus and the Levator palpebrae, sends a branch inwards, across the pulley of the Superior oblique muscle, to supply the parts of the inner canthus; and at the supraorbital foramen, frequently transmits a branch to the diploe. The Ethmoidal branches are two in number ; posterior and anterior. The former, Avhich is the smaller, passes through the posterior ethmoidal foramen, sup- plies the posterior ethmoidal cells, and, entering the cranium, gives off a meningeal branch, which supplies the adjacent dura mater, and nasal branches, Avhich descend into the nose through apertures in the cribriform plate, anastomosing Avith branches of the spheno-palatine. The anterior ethmoidal artery accompanies the nasal nerve through the anterior ethmoidal foramen, supplies the anterior ethmoidal cells and frontal sinuses, and, entering the cranium, divides into a meningeal branch, Avhich supplies the adjacent dura mater, and a nasal branch, Avhich descends into the nose, through an aperture in the cribriform plate. The Palpebral arteries, two in number, superior and inferior, arise from the ophthalmic, opposite the pulley of the Superior oblique muscle; they encircle the eyelids near their free margin, forming a superior and an inferior arch, Avhich lie betAveen the Orbicularis muscle and tarsal cartilage. The superior palpebral inos- culates at the outer angle of the orbit with the orbital branch of the temporal artery. The inferior branch anastomoses Avith the orbital branch of the infraorbital artery, at the inner side of the lid; from this anastomosis a branch passes to the nasal duct, ramifying, in its mucous membrane, as far as the inferior meatus. The Frontal artery, one of the terminal branches of the ophthalmic, passes from the orbit at its inner angle, and, ascending on the forehead, supplies the muscles, integument, and pericranium, anastomosing Avith the supraorbital artery. The Nasal artery, the other terminal branch of the ophthalmic, emerges from the orbit aboAre the tendo oculi, and, after giving a branch to the lachrymal sac, divides into two, one of Avhich anastomoses with the angular artery, the other branch, the dorsalis nasi, runs along the dorsum of the nose, supplies its entire surface, and anastomoses Avith the artery of the opposite side. The Ciliary arteries are divisible into three groups, the short, long, and anterior. The Short Ciliary arteries, from twelve to fifteen in number, arise from the ophthalmic, or some of its branches; they surround the optic nerve as they pass forwards to the posterior part of the eyeball, pierce the sclerotic coat around the entrance of this nerve, and supply the choroid coat and ciliary processes. The Long Ciliary arteries, tAvo in number, also pierce the posterior part of the sclerotic, and run forAvards, along each side of the eyeball, between the sclerotic and choroid, to the ciliary ligament, where they divide into tAvo branches ; these form an arterial circle around the circumference of the iris, from Avhich numerous radiating branches pass forAvards, in its substance, to its free margin, where they form a second arterial circle around its pupillary margin. The Anterior Ciliary arteries are derived from the muscular branches; they pierce the sclerotic a short distance from the cornea, and terminate in the great arterial circle of the iris. The Arteria Centralis Retinas is one of the smalfbst branches of the ophthalmic artery. It arises near the optic foramen, pierces the optic nerve obliquely, and runs forwards, in the centre of its substance, to the retina, in Avhich its branches are distributed as far forAvards as the ciliary process. In the human foetus, a small vessel passes forwards, through the vitreous humor, to the posterior surface of the capsule of the lens. The Muscular branches, two in number, superior and inferior, supply the muscles of the eyeball. The superior, the smaller, often wanting, supplies the Levator palpebrae, Superior rectus, and Superior oblique. The inferior, more constant in its existence, passes forwards, betAveen the optic nerve and Inferior rectus, and is distributed to the External and Inferior recti, and Inferior oblique. This vessel gives off most of the anterior ciliary arteries. The Cerebral Branches of the internal carotid are, the anterior cerebral, the middle cerebral, the posterior communicating, and the anterior choroid. OF THE BRAIN. 337 The Anterior Cerebral arises from the internal carotid, at the inner extremity of the fissure of Sylvius. It passes forAvards in the great longitudinal fissure betAveen the two anterior lobes of the brain, being connected soon after its origin with the vessel of the opposite side by a short anastomosing trunk, about tAvo lines in length, Fig. 196.—The Arteries at the Base of the Brain. The Right Half of the Cerebellum and Pons have been removed. the anterior communicating. The two anterior cerebral arteries, lying side by side, curve around the anterior border of the corpus callosum, and run along its upper surface to its posterior part, where they terminate by anastomosing with the pos- terior cerebral arteries. They supply the olfactory and optic nerves, the under 24 999 338 ARTERIES. surface of the anterior lobes, the third ventricle, the anterior perforated space the corpus callosum, and the inner surface of the hemispheres. The Anterior Communicating artery is a short branch, about two lines in length, but of moderate size, connecting together the twro anterior cerebral arteries across the lon- gitudinal fissure. Sometimes this vessel is wanting, the two arteries joining together to form a single trunk, Avkieh afterwards subdivides. Or the vessel may be wholly or partially subdivided into tAvo; frequently, it is longer and smaller than usual." The Middle Cerebral artery, the largest branch of the internal carotid, passes obliquely outAvards along the fissure of Sylvius, Avithin which it diAudes into three branches; an anterior, Avhich supplies the pia mater, investing the surface of the anterior lobe ; a posterior, which supplies the middle lobe; and a median branch which supplies the small lobe at the outer extremity of the Sylvian fissure. Near its origin, this vessel gives off numerous small branches,, which enter the substantia perforata, to be distributed to the corpus striatum. The Posterior Communicating artery arises from the back part of the internal carotid, runs directly backAATards, and anastomoses Avith the posterior cerebral a branch of the basilar. This artery varies considerably in size, being sometimes small, and occasionally so large that the posterior cerebral may be considered as arising from the internal carotid rather than from the basilar. It is frequently larger on one side than on the other side. The Anterior Choroid is a small but constant branch, which arises from the back part of the internal carotid, near the posterior communicating artery. Passing backAvards and outAvards, it enters the descending horn of the lateral ventricle, beneath the edge of the middle lobe of the brain. It is distributed to the hippo- campus major, corpus fimbriatum, and choroid plexus. ARTERIES OF THE UPPER EXTREMITY. The artery Avhich supplies the upper extremity continues as a single trunk from its commencement, as far as the elboAv ; but different portions of it have received different names, according to the region through Avhich it passes. Thus, that part of the vessel Avhich extends from its origin, as far as the outer border of the first rib, is termed the subclavian; beyond this point to the lower border of the axilla, it is termed the axillary; and from the lower margin of the axillary space to the bend of the elbow, it is termed brachial; here, the single trunk terminates by divid- ing into two branches, the radial and ulnar, an arrangement precisely similar to what occurs in the lower limb. Subclavian Arteries. The subclavian artery on the right side arises from the arteria innominata, oppo- site the right sterno-clavicular articulation ; on the left side, it arises from the arch of the aorta. It follows, therefore, that these two vessels must, in the first part of their course, differ in their length, their direction, and in their relation with neighboring parts. _ In order to facilitate the description of these vessels, more especially in a sur- gical point of view, each subclavian artery has been subdivided into three parts. The first portion, on the right side, ascends obliquely outAvards, from the origin of the vessels to the inner border of the Scalenus anticus. On the left side, it ascends perpendicularly to the inner border of this muscle. The second part passes out- wards, behind the Scalenus anticus; and the third part passes from the outer mar- gin of this muscle, beneath the clavicle, to the lower border of the first rib, where it becomes the axillary artery. The first portions of these two vessels differ so much m their course, and in their relation with neighboring parts, that they will be described separately. The second and third parts are precisely alike on both sides. First Part of the Right Subclavian Artery (Figs. 188, 189). It arises from the arteria innominata, opposite the right sterno-clavicular arti- SUBCLAVIAN. 339 culation, passes upAvards and outwards across the root of the neck, and terminates at the inner margin of the Scalenus anticus muscle. In this part of its course, it ascends a little above the clavicle, the extent to Avhich it does so varying in differ- ent cases. It is coA^ered, in front, by the integument, superficial and deep fasciae, Platysma, the clavicular origin of the Sterno-mastoid, the Sterno-hyoid and Sterno- thyroid muscles, and another layer of the deep fascia; It is crossed by the internal jugular and vertebral veins, and by the pneumogastric, the cardiac branches of the sympathetic, and phrenic nerves. Beneath, the artery is invested by the pleura, and behind, it is separated by a cellular interATal from the Longus colli, the transverse process of the seventh cervical vertebra, and the sympathetic; the recur- rent laryngeal nerve Avinding around the lower and back part of the vessel. The subclavian vein lies belowT the subclavian artery, immediately behind the clavicle. Plan of Relations of First Portion of Right Subclavian Artery. In front. Integument, superficial and deep fasciae. Platysma. Clavicular origin of Sterno-mastoid. Sterno-hyoid and Sterno-thyroid. Internal jugular and vertebral veins. Pneumogastric, cardiac, and phrenic nerves. Beneath. Pleura. Behind. Recurrent laryngeal nerve. Sympathetic. Longus colli. Transverse process of seventh cervical vertebra. First Part of the Left Subclavian Artery (Fig. 187). It arises from the end of the transverse portion of the arch of the aorta, opposite the second dorsal A^ertebra, and ascends to the inner margin of the first rib, behind the insertion of the Scalenus anticus muscle. This vessel is, therefore, longer than the right, situated more deeply in the cavity of the chest, and directed almost vertically upwards, instead of arching outwards like the vessel of the opposite side. It is in relation, in front, Avith the pleura, the left lung, the pneumogastric, phrenic, and cardiac nerves, AA'hich lie parallel with it, the left carotid artery, left internal jugular and innominate veins, and is covered by the Sterno-thyroid, Sterno- hyoid, and Sterno-mastoid muscles; behind, with the oesophagus, thoracic duct, infe- rior cervical ganglion of the Sympathetic, Longus colli, and vertebral column. To its inner side is the oesophagus, trachea, and thoracic duct; to its outer side, the pleura. Plan of Relations of First Portion of Left Subclavian Artery. In front. Pleura and left lung. Pneumogastric, cardiac, and phrenic nerves. Left carotid artery. Left internal jugular and innominate veins. Sterno-thyroid, Sterno-hyoid, and Sterno-mastoid muscles. Inner side (Esophagus. Trachea. Thoracic duct Outer side. Pleura. 310 ARTERIES. Behind. (Esophagus and thoracic duct. Inferior cervical ganglion of sympathetic. Longus colli and vertebral column. The relations of the second and third portions of the subclavian arteries are precisely similar on both sides. The Second Portion of the Subclavian Artery lies betAveen the tAvo Scaleni muscles; it is very short, and forms the highest part of the arch described by that vessel. Relations. It is covered, in front, by the integument, Platysma, Sterno-mastoid, cervical fascia, and by the phrenic nerve, Avhich is separated from the artery by the Scalenus anticus muscle. Behind, it is in relation with the Middle scalenus. Above, with the brachial plexus of nerves. Below, Avith the pleura. The sub- clavian vein lies beloAv the artery, separated from it by the Scalenus anticus. Plan of the Relations of the Second Portion of the Subclavian Artery. In front. Platysma and Sterno-mastoid. Phrenic nerve. Cervical fascia. Scalenus anticus. / Sub- \ Above. I ^vian \ ^^ Brachial plexus. I Seconder-/ Pleura. Bihind. Middle scalenus. The Third Portion of the Subclavian Artery passes downwards and outwards from the outer margin of the Scalenus anticus to the lower border of the first rib, where it becomes the axillary artery. This portion of the vessel is the most superficial, and is contained in a triangular space, the base of which is formed in front by the Anterior scalenus, and the two sides by the Omo-hyoid above and the clavicle below. Relations. It is covered, in front, by the integument, the superficial and deep fasciae, the Platysma; and by the clavicle, the Subclavius muscle, and the supra- scapular artery and vein below; the clavicular descending branches of the cervical plexus and the nerve to the Subclavius pass vertically downwards in front of the artery. The external jugular vein crosses it at its inner side, and receives the suprascapular and transverse cervical veins, which occasionally form a plexus in front of it. The subclavian vein is below the artery, lying close behind the clavicle. Behind, it lies on the Scalenus medius muscle. Above it, and to its outer side, are the brachial plexus, and Omo-hyoid muscle. Below, it rests on the outer surface of the first rib. Plan of the Relations of the Third Portion of the Subclavian Artery. In front. Integument, fasciae, and Platysma. The external jugular, suprascapular, and transverse cervical veins. Descending branches of cervical plexus. Subclavius muscle, suprascapular vessels, and clavicle. Above. / Sub" Brachial plexus. ( Artery. ) Below. Omo-hyoid. \ Third / First rib. Portion Behind. Scalenus medius. SUBCLAVIAN. 341 Peculiarities. The subclavian arteries vary in their origin, their course, and in the height to which they rise in the neck. The origin of the right subcla\lan from the innominate takes place, in some cases, above the sterno-clavicular articulation; more frequently, in the cavity of the thorax, below that joint. Or the artery may arise as a separate trunk from the arch of the aorta; in such cases it may be either the first, second, third, or even the last branch derived from that vessel: in the majority of cases, it is the first or last, rarely the second or third. When it is the first branch, it occupies the ordinary position of the innominate artery; when the second or third, it gains its usual position by passing behind the right carotid; and when the last branch, it arises from the left extremity of the arch, at its upper or back part, and passes obliquely towards the right side, behind the oesophagus and right carotid, some- times between the oesophagus and trachea, to the upper border of the first rib, where it fol- lows its ordinary course. In very rare instances, this vessel arises from the thoracic aorta, as low down as the fourth dorsal vertebra. Occasionally, it perforates the Anterior scalenus; more rarely it passes in front of this muscle : sometimes the subclavian vein passes with the artery behind the Scalenus. The artery sometimes ascends as high as an inch and a half above the clavicle, or to any intermediate point between this and the upper border of this bone, the right subclavian usually ascending higher than the left. The left subclavian is occasionally joined at its origin with the left carotid. Surgical Anatomy. The relations of the subclavian arteries of the two sides having been examined, the student should direct his attention to consider the best position in which com- pression of the vessel may be effected, or in what situation a ligature may be best applied iu cases of aneurism or wounds. Compression of the subclavian artery is required in cases of operations about the shoulder, in the axilla, or at the upper part of the arm; and the student will observe that there is only one situation in which it can be effectually applied, viz., where the artery passes across the outer surface of the first rib. In order to compress the vessel in this situation, the shoulder should be depressed, and the surgeon, grasping the side of the neck, may press with his thumb in the hollow behind the clavicle downwards against the rib ; if from any cause the shoulder cannot be sufficiently depressed, pressure may be made from before backwards so as to compress the artery against the Middle scalenus and transverse process of the seventh cervical vertebra. Ligature of die subclavian artery may be required in cases of wounds of the axillary artery, or in aneurism of that vessel; and the third part of the artery is consequently that which is most favorable for such an operation, on account of its being comparatively super- ficial and most remote from the origin of the large branches. In those cases where the cla- vicle is not displaced, this operation may be performed with comparative facility ; but where the clavicle is elevated from the presence of a large aneurismal tumor in the axilla, the artery is placed at a great depth from the surface, which materially increases the difficulty of the operation. Under these circumstances, it becomes a matter of importance to consider the height to which this vessel reaches above the bone. In ordinary cases its arch is about half an inch above the clavicle, occasionally as high as an inch and a half, and sometimes so low as to be on a level with its upper border. If displacement of the clavicle occurs, these varia- tions will necessarily make the operation more or less difficult, according as the vessel is more or less accessible. The chief points in the operation of tying the third portion of the subclavian artery are as follows : The patient being placed on the table in the horizontal position, and the shoulder depressed as much as possible, the integument should be drawn downwards upon the clavicle and an incision made through it upon that bone from the anterior border of the Trapezius to the posterior border of the Sterno-mastoid, to which may be added a short vertical incision meeting the centre of the preceding; the Platysma myoides and cervical fascia should be divided upon a director, and if the interval between the Trapezius and Sterno-mastoid muscles be insufficient for the performance of the operation, a portion of one or both may be divided. The external jugular vein will now be seen towards the inner side of the wound ; this and the scapular and transverse cervical veins which terminate in it should be held aside, and, if divided, both ends should be included in a ligature : the supra- scapular artery should be avoided, and the Omo-hyoid muscle must now be looked for, and held aside if necessary. In the space beneath this muscle, careful search must be made for die vessel; the deep fascia having been divided with the finger-nail or silver scalpel, the outer margin of the Scalenus muscle must be felt for, and the finger being guided by it to the first rib, the pulsation of the subclavian artery will be felt as it passes over its surface. The 312 ARTERIES. aneurism needle may then be passed around the vessel from before backwards, by which means the veins will be avoided, care being taken not to include a branch of the brachial plexus instead of the artery in the ligature. If the clavicle is so raised by the tumor that the application of the ligature cannot be effected in this situation, the artery may be tied above the first rib, or even behind the Scalenus muscle : the difficulties of the operation in such a case will be materially increased, on account of the greater depth of the artery, and alteration of the position of the surrounding parts. The second division of the subclavian artery, from being that portion which rises highest in the neck, has been considered favorable for the application of the ligature, where it is diffi- cult to apply it in the third part of its course. There are, however, many objections to the operation in this situation. It is necessary to divide the Scalenus anticus muscle, upon which lies the phrenic nerve, and at the inner side of which is situated the internal jugular vein; a wound of either of these structures might lead to the most dangerous consequences. Again, the artery is in contact, below, with the pleura, which must also be avoided ; and lastly, the proximity of so many of its larger branches arising internal to this point, must be a still fur- ther objection to the operation. If, however, it has been determined upon to perform the operation in this situation, it should be remembered that it occasionlly happens that the artery passes in front of the Scalenus anticus, or through the fibres of that muscle; or. that the vein sometimes passes with the artery behind the Scalenus anticus. In those cases of aneurism of the axillary or subclavian artery which encroach upon the outer portion of the Scalenus muscle to such an extent that a ligature cannot be applied in that situation, it may be deemed advisable, as a last resource, to tie the first portion of the subclavian artery. On the left side, this operation is quite impracticable; the great depth of the artery from the surface, its intimate relation with the pleura, and its close proximity with so many important veins and nerves, present a series of difficulties which it is impos- sible to overcome. On the right side, the operation is practicable, and has been performed, though not with success. The main objection to the operation in this situation is the small- ness of the interval which usually exists between the commencement of the vessel and the origin of the nearest branch. This operation may be performed in the following manner: The patient being placed on a table in the horizontal position, with the neck extended, an incision should be made parallel with the inner part of the clavicle, and a second along the inner border of the Sterno-mastoid, meeting it at right angles. The sternal attachment of the Sterno-mastoid may now be divided on a director, and turned outwards; a few small arteries and veins, and occasionally the anterior jugular, must be avoided and the Sterno- hyoid and thyroid muscles divided in the same manner as the preceding muscle. After tear- ing through the deep fascia with the finger-nail, the internal jugular vein will be seen cross- ing the artery; this should be pressed aside, and the artery secured by passing the needle from below upwards, by which the pleura is more effectually avoided. The exact position of the vagus nerve, the recurrent laryngeal, the phrenic, and sympathetic nerves, should be remembered, and the ligature should be applied near the origin of the vertebral, in order to afford as much room as possible for the formation of a coagulum between the ligature and the origin of the vessel. It should be remembered that the right subclavian artery is occa- sionally deeply placed in the first part of its course, when it arises from the left side of the aortic arch, and passes in such cases behind the oesophagus, or between it and the trachea. Branches of the Subclavian Artery (Fig. 197). These are four in number ; three arising from the first portion of the vessel, the vertebral, the internal mammary, and the thyroid axis; and one from the second portion, the superior intercostal. The vertebral arises from the upper and back part of the first portion of the artery ; the thyroid axis from the front, and the internal mammary from the under part of this vessel. The superior intercostal is given off from the upper and back part of the second portion of the artery. On the left side, the second portion usually gives off no branch, the superior intercostal arising to the inner side of the Scalenus anticus. On both sides of the body, the first three branches arise close together at the inner margin of the Scalenus anticus, in the majority of cases a free interval of half an inch to an inch existing between the commencement of the artery and the origin of the nearest branch; in a smaller number of cases, an interval of more than an inch existed, never exceeding an inch VERTEBRAL. 343 and three-quarters. In a very feAV in- stances, the interval was less than half an inch. Vertebral Artery (Fig. 194). The vertebral artery is generally the first and largest branch of the subclavian; it arises from the upper and back part of the first portion of the vessel, and passing "upwards, enters the foramen in the trans- verse process of the sixth cervical verte- bra, and ascends through the foramina in the transverse processes of all the ver- tebrae. Above the upper border of the axis, it inclines outwards and upwards to the foramen in the transverse process of the atlas, through which it passes; it then winds backwards behind its articular process, runs in a deep groove on the surface of the posterior arch of this bone, and piercing the posterior occipito-atloid liga- ment and dura mater, enters the skull through the foramen magnum. It then passes in front of the medulla oblongata, and unites with the vessel of the opposite side, at the lower border of the pons Varolii, to form the basilar artery. At its origin, it is situated behind the internal jugular vein and inferior thyroid artery, and, near the spine, lies between the Longus colli and Scalenus anticus muscles, having the thoracic duct in front of it on the left side. Within the fora- mina formed by the transverse processes of the vertebrae, it is accompanied by a plexus of nerves from the sympathetic, and lies betAveen the vertebral vein, which is in front, and the cervical nerves, Avhicli issue from the invertebral foramina behind it. Whilst Avinding around the articular process of the atlas, it is con- tained in a triangular space formed by the Rectus posticus minor, the Superior and Inferior oblique muscles; and is covered by the Rectus posticus major and Com- plexus. And Avithin the skull, as it winds around the medulla oblongata, it is placed betAveen the hypoglossal and anterior root of the sub-occipital nerves. Branches. These may be divided into tAvo sets, those given off in the neck, and those Avithin the cranium. Cervical Branches Cranial Branches. The Lateral Spinal Branches enter the spinal canal through the intervertebral foramina, each dividing into two branches. Of these, one passes along the roots of the nerves to supply the spinal cord and its membranes, anastomosing with the other spinal arteries; the other is distributed to the posterior surface of the bodies of the vertebrae. Several large Aluscular Branches are given off to the deep muscles of the neck where the vertebral artery curves around the articular process of the atlas. They anastomose with the occipital and deep cervical arteries. The Posterior Meningeal are one or two small branches given off from the ver- tebral opposite the foramen magnum. They ramify between the bone and dura mater in the cerebellar fossae, and supply the falx cerebelli. The Anterior Spinal is a small branch, larger than the posterior spinal, which arises near the termination of the vertebral, and unites Avith its fellow of the op- posite side in front of the medulla oblongata. The single trunk thus formed descends a short distance on the anterior aspect of the spinal cord, and joins with a Fig. 197.—Plan of the Branches of the Right Subclavian Artery. I Lateral spinal. \ Muscular. Posterior meningeal. Anterior spinal. Posterior spinal. Inferior cerebellar. 314 ARTERIES. succession of small branches Avhich enter the spinal canal through some of the intervertebral foramina; these branches are derived from the vertebral and ascend- ing cervical, in the neck; from the intercostal, in the dorsal region; and from the lumbar, ilio-lumbar, and lateral sacral arteries, in the lower part of the spine. They unite, by means of ascending and descending branches, to form a single anterior median artery, Avhich extends as low down as the loAver part of the spinal cord. This vessel is placed beneath the pia mater along the anterior median fissure; it supplies that membrane and the substance of the cord, and sends off branches at its lower part to be distributed to the cauda equina. The Posterior Spinal arises from the vertebral, at the side of the medulla oblongata; passing backwards to the posterior aspect of the spinal cord, it descends on either side, lying behind the posterior roots of the spinal nerves, and is reinforced by a succession of small branches, Avhich enter the spinal canal through the intervertebral foramina, and by which it is continued to the lower part of the cord, and to the cauda equina. Branches from these vessels form a free anastomosis around the posterior roots of the spinal nerves, and communicate, by means of very tortuous transverse branches, with the vessel of the opposite side. At its commencement, it gives off an ascending branch, which terminates on the sides of the fourth ventricle. The Inferior Cerebellar artery, the largest branch of the vertebral, Avinds back- Avards around the upper part of the medulla oblongata, passing betAveen the origin of the spinal accessory and pneumogastric nerves, over the restiform body to the under surface of the cerebellum, Avhere it divides into tAvo branches: an internal one, which is continued backwards to the notch betAveen the tAvo hemispheres of the cerebellum; and an external one, Avhich supplies the under surface of the cerebel- lum, as far as its outer border, Avhere it anastomoses Avith the superior cerebellar. Branches from this artery supply the choroid plexus of the fourth ventricle. The Basilar artery, so named from its position at the base of the skull, is a single trunk, formed by the junction of the two vertebral arteries; it extends from the posterior to the anterior border of the pons Varolii, Avhere it divides into two terminal branches, the posterior cerebral arteries. Its branches are, on each side, the following :— Transverse. Superior cerebellar. Anterior cerebellar. Posterior cerebral. The Transverse branches supply the pons Varolii and adjacent parts of the brain; one accompanies the auditory nerve into the internal auditory meatus; and another, of larger size, passes along the crus cerebelli, to be distributed to the anterior border of the under surface of the cerebellum. It is called the anterior {inferior) cerebellar artery. The Superior Cerebellar arteries arise near the termination of the basilar. They Avind round the crus cerebri, close to the fourth nerve, and arriving at the upper surface of the cerebellum, divide into branches Avhich supply the pia mater, covering its surface, anastomosing with the inferior cerebellar. It gives several branches to the pineal gland, and also to the velum interpositum. The Posterior Cerebral arteries, the two terminal branches of the basilar, are larger than the preceding, from which they are separated near their origin by the third nerves. Winding around the crus cerebri, they pass to the under surface of the posterior lobes of the cerebrum, which they supply, anastomosing with the anterior and middle cerebral arteries. Near their origin they give off a number of parallel branches, which enter the posterior perforated spot, and receive the posterior communicating arteries from the internal carotid. They also give off a branch, the posterior choroid, which supplies the velum interpositum and choroid plexus, entering the interior of the brain, beneath the posterior border of the corpus callosum. Circle of Willis. The remarkable anastomosis which exists betAveen the branches of the internal carotid and vertebral arteries, at the base of the brain, INFERIOR THYROID; SUPRASCAPULAR. 345 constitutes the circle of Willis. It is formed, in front, by the anterior cerebral and anterior communicating arteries; on each side, by the trunk of the internal carotid, and the posterior communicating ; behind, by the posterior cerebral, and point of the basilar. It is by this anastomosis that the cerebral circulation is equalized, and provision made for effectually carrying it on, if one or more of the branches are obliterated. The parts of the brain included Avithin this arterial circle are, the lamina cinerea, the commissure of the optic nerves, the infundi- bulum, the tuber cinereum, the corpora albicantia, and the pars perforata postica. Thyroid Axis. The thyroid axis is a short, thick trunk, Avhich arises from the forepart of the first portion of the subclavian artery, close to the inner side of the Scalenus anticus muscle, and divides, almost immediately after its origin, into three branches, the inferior thyroid, suprascapular, and transversalis colli. The Inferior Thyroid Artery passes upwards, in a serpentine course, behind the sheath of the carotid vessel and sympathetic nerve, the middle cervical ganglion resting upon this vessel, and is distributed to the under surface of the thyroid gland, anastomosing with the superior thyroid, and with the corre- sponding artery of the opposite side. Its branches are the Laryngeal. (Esophageal. Tracheal. Ascending cervical. The Laryngeal branch ascends upon the trachea to the back part of the larynx, and supplies the muscles and the mucous membrane of this part. The Tracheal branches are distributed over the trachea, anastomosing belowr with the bronchial arteries. The Oesophageal branches are distributed to the oesophagus. The Ascending Cervical artery is a small branch Avhich arises from the inferior thyroid, just Avhere that vessel is passing behind the carotid artery, and runs up the neck in the interval betAveen the Scalenus anticus and Rectus anticus major. It gives branches to the muscles of the neck, Avhich communicates Avith those sent out from the vertebral, and sends one or two through the intervertebral foramina, along the cervical nerves, to supply the bodies of the vertebrae, the spinal cord, and its membranes. The Suprascapular Artery, smaller than the transverse cervical, passes obliquely from Avithin outAvards, across the root of the neck. It at first lies on the loAver part of the Scalenus anticus, being covered by the Sterno-mastoid ; it then crosses the subclavian artery, and runs outwards behind, and parallel Avith, the clavicle and Subclavius muscle, and beneath the posterior belly of the Omo- hyoid, to the superior border of the scapula, Avhere it passes over the ligament of the suprascapular notch to the supraspinous fossa. In this situation it lies close to the bone, and ramifies betAveen it and the Supraspinatus muscle to Avhich it is mainly distributed, giving off a communicating branch, which crosses the neck of the scapula, to reach the infraspinous fossa, where it anastomoses with the dorsal branch of the subscapular artery. Besides distributing branches to the Sterno- mastoid, and neighboring muscles, it gives off a supra-acromial branch, Avhich, piercing the Trapezius muscle, supplies the cutaneous surface of the acromion, anastomosing with the acromial thoracic artery. As the artery passes across the suprascapular notch, a branch descends into the subscapular fossa, ramifies beneath that muscle, and anastomoses with the posterior and subscapular arteries. It also supplies the shoulder joint. The Transversalis Colli passes transversely outAvards, across the upper part of the subclavian triangle, to the anterior margin of the Trapezius muscle, beneath which it divides into tAvo branches, the superficial cervical, and the posterior scapular. In its course across the neck, it passes in front of the Scaleni muscles and the brachial plexus, betAveen the divisions of which it sometimes passes, and 346 ARTERIES. is covered in by the Platysma, Sterno-mastoid, Omo-hyoid, and Trapezius muscles. The Superficial Cervical ascends beneath the anterior margin of the Tra- pezius, distributing branches to it, and to the neighboring muscles and glands in the neck. The Posterior Scapular, the continuation of the transverse cervical, passes beneath the Levator anguli scapulae to the superior angle of the scapula, and descends along the posterior border of that bone as far as the inferior angle, where it anastomoses Avith the subscapular branch of the axillary. In its course it is covered in by the Rhomboid muscles, supplying these, the Latissimus dorsi, and Trapezius, and anastomoses Avith the suprascapular and subscapular arteries, and Avith the posterior branches of some of the intercostal arteries. Peculiarities. The Superficial Cervical frequently arises as a separate branch from the thyroid axis; and the posterior scapular, from the third, more rarely from the second, part of the subclavian. The Internal Mammary arises from the under surface of the first portion of the subclavian artery, opposite the thyroid axis. It descends behind the clavicle, to the inner surface of the anterior Avail of the chest, resting upon the costal cartilages, a short distance from the margin of the sternum; and, at the interval between the sixth and seventh cartilages, divides into two branches, the musculo- phrenic, and superior epigastric. At its origin, it is covered by the internal jugular and subclavian veins, and crossed by the phrenic nerve. In the upper part of the* thorax, it lies upon the costal cartilages, and internal Intercostal muscles in front, covered by the pleura behind. At the lower part of the thorax, the Triangularis sterni separates this vessel from the pleura. It is accompanied by two veins, which join at the upper part of the thorax into a single trunk. The branches of the internal mammary are, Comes nervi phrenici (superior phrenic). Anterior intercostal. Mediastinal. Perforating. Pericardiac. Musculophrenic. Sternal. Superior epigastric. INTERNAL MAMMARY; SUPERIOR INTERCOSTAL. 347 The Comes Nervi Phrenici (Superior Phrenic) is a long slender branch, which accompanies the phrenic nerve, between the pleura and pericardium, to the Dia- phragm, to which it is distributed ; anastomosing with the other phrenic arteries from the internal mammary, and abdominal aorta. The Mediastinal Branches are small vessels, which are distributed to the areolar tissue in the anterior mediastinum, and the remains of the thymus gland. The Pericardiac Branches supply the upper part of the pericardium, the lower part receiving branches from the musculophrenic artery. Some sternal branches are distributed to the Triangularis sterni, and both surfaces of the sternum. The Anterior Intercostal Arteries supply the five or six upper intercostal spaces. The branch corresponding to each space passes outAvards, and soon divides into two, which run along the opposite edges of the ribs, and inosculate with the inter- costal arteries from the aorta. They are at first situated betAveen the .pleura and the internal Intercostal muscles, and then between the two.layers of these muscles. They supply the Intercostal and Pectoral muscles, and the mammary gland. The Anterior or Perforating Arteries correspond to the five or six upper inter- costal spaces. They arise from the internal mammary, pass forwards through the intercostal spaces, and, curving outwards, supply the Pectoralis major, and the in- tegument. Those which correspond to the first three spaces are distributed to the mammary gland. In females, during lactation, these branches are of large size. The Musculophrenic Artery is directed obliquely downwards and outwards. behind the cartilages of the false ribs, perforating the Diaphragm at the eighth or ninth rib, and terminating, considerably reduced in size, opposite the last inter- costal space. It gives off anterior intercostal arteries to each of the intercostal spaces across Avhich it passes ; they diminish in size as the spaces decrease in length, and are distributed in a manner precisely similar to the anterior intercostals from the internal mammary. It also gives branches backAvards to the Diaphragm, and downwards to the abdominal muscles. The Superior Epigastric continues in the original direction of the internal mam- mary, descends behind the Rectus muscle, and, perforating its sheath, divides into branches which supply the Rectus, anastomosing Avith the epigastric artery from the external iliac. Some vessels perforate the sheath of the Rectus, and supply the muscles of the abdomen and the integument, and a small branch A\liich passes inwards upon the side of the ensiform appendix, anastomoses in front of that car- tilage with the artery of the opposite side. The Superior Intercostal arises from the upper and back part of the second portion of the subclavian artery on the right side, and to the inner side of the Scalenus anticus on the left side. Passing backAvards it gives off the deep cer- vical branch, and descends behind the pleura in front of the necks of the first tAvo ribs, and inosculates Avith the first aortic intercostal. In the first intercostal space, it gives off a branch Avhich is distributed in a similar manner with the aortic in- tercostals. The branch for the second intercostal space usually joins with one from the first aortic intercostal. Each intercostal gives off a branch to the posterior spinal muscles, and a small one, Avhich passes through the corresponding inter- vertebral foramen to the spinal cord and its membranes. The Deep Cervical Branch (Profunda Cervicis) arises, in most cases, from the superior intercostal, and is analogous to the posterior branch of an aortic inter- costal artery. Passing backwards, between the transverse process of the seventh cervical vertebra and the first rib, it ascends the back part of the neck, between the Complexus and Semispinalis colli muscles, as high as the axis, supplying these and adjacent muscles, and anastomosing with the arteria princeps cervicis of the occipital, and with branches which pass outAvards from the vertebral. Surgical Anatomy of the Axilla. The Axilla is a conical space situated betAveen the upper and lateral parts of the chest, and inner side of the arm. 34 s SURGICAL ANATOMY Boundaries. Its apex, which is directed upwards towards the root of the neck, corresponds to the interval between the first rib internally, the superior border of" the scapula externally, and the clavicle and Subclavius muscle in front. The base, directed downwards, is formed by the integument, and a thick layer of fascia, ex- tending between the lower border of the Pectoralis major in front, and the lower Fig. 199.—The Axillary Artery, and its Branches <* nferi border of the Latissimus dorsi behind; it is broad internally, at the chest, but narrow and pointed externally, at the arm. Its anterior boundary is formed by the Pectoralis major and minor muscles, the former covering in the whole of the anterior wall of the axilla, the latter covering only its central part. Its posterior boundary, which extends somewhat loAver than the anterior, is formed by the Sub- scapularis above, the Teres major and Latissimus dorsi below. On the inner side are the first four ribs and their corresponding Intercostal muscles, and part of the Serratus magnus. On the outer side, .where the anterior and posterior boundaries converge, the space is narrow, and bounded by the humerus, the Coraco-brachialis and Biceps muscles. Contents This space contains the axillary vessels, and brachial plexus of nerves with their branches, some branches of the intercostal nerves, a large number of lymphatic glands, all connected together by a quantity of fat and loose areolar tissue. J Relation of Vessels and Nerves. The axillary artery and vein, with the brachial plexus ot nerves, extend obliquely along the outer boundary of the axillary space, from its apex to its base, and are placed much nearer the anterior than the posterior vail, the vein lying to the inner or thoracic side of the artery, and altogether con- cealing it. At the forepart of the axillary space, in contact with the Pectoral muscles, are the thoracic branches of the axillary artery, and along the anterior margin of the axilla, the long thoracic artery extends to the side of the chest. At the back part, in contact with the lower margin of the Subscapularis muscle, are OF THE AXILLA. 349 the subscapular \ressels and nerves ; winding around the loAver border of this muscle, are the dorsalis scapulae artery and veins; and toAvards the outer extremity of the muscle, the posterior circumflex vessels and nerve are seen curving backwards to the shoulder. Along the inner or thoracic side, no vessel of any importance exists, its upper part being crossed by a feAV small branches from the superior thoracic artery. There are some important nerves, however, in this situation ; the posterior thoracic or external respiratory nerve descending on the surface of the Serratus magnus, to which it is distributed; and perforating the upper and anterior part of this Avail, are the intercosto-humeral nerves, which pass across the axilla to the inner side of the arm. The cavity of the axilla is filled by a quantity of loose areolar ..tissue, a large number of small arteries and veins, all of Avhich are, however, of inconsiderable size, and numerous lymphatic glands; these are from ten to tAvelve in number, and situated chiefly on the thoracic side, and lower and back part of this space. The student should attentively consider the relation of the vessels and nerves in the several parts of the axilla; for it not unfrequently happens that the surgeon is called upon to extirpate diseased glands, or to remove a tumor from this situation. In performing such an operation, it will be necessary to proceed with much caution in the direction of the outer Avail and apex of the space, as here the axillary vessels will be in danger of being Avounded. Towards the posterior Avail, it will be necessary to avoid the subscapular, dorsalis scapulae, and posterior circumflex vessels, and, along the anterior Avail, the thoracic branches. It is only along the inner or thoracic wall, and in the centre of the axillary cavity, that there are no vessels of any importance; a most fortunate circumstance, for it is in this situation, more especially, that tumors requiring removal are most frequently situated. The Axillary Artery. The axillary artery, the continuation of the subclavian, commences at the lower border of the first rib, and terminates at the lower border of the tendons of the Latissimus dorsi and Teres major muscles, Avhen it becomes the brachial. Its direction varies Avith the position of the limb : Avhen the arm lies by the side of the chest, the vessel forms a gentle curve, the convexity being upwards and outAvards; Avhen it is directed at right angles Avith the trunk, the vessel is nearly straight; and if elevated still higher, it describes a curve, the concavity of Avhich is directed upAvards. At its commencement the artery is very deeply situated, but near its termination is superficial, being covered only by the skin and fascia. The description of the relations of this vessel may be facilitated by its division into three portions : the first portion being that above the Pectoralis minor; the second portion, beneath; and the third, below that muscle. The first portion of the axillary artery is in relation, in front, Avith the clavicular portion of the Pectoralis major, the costo-coracoid membrane, and the cephalic vein ; behind, with the first intercostal space, the corresponding Intercostal muscle, the first serration of the Serratus magnus, and the posterior thoracic nerve; on its outer side, Avith the brachial plexus, from Avhich it is separated by a little cellular interval; on its inner, or thoracic side, Avith the axillary vein. Relations of First Portion of the Axillary Artery. In front. Pectoralis major. Costo-coracoid membrane. Cephalic vein. Outer side. | First ' ) Inner side. Brachial plexus. V Portion. / Axillary vein. 350 ARTERIES. Behind. First intercostal space, and Intercostal muscle. First serration of Serratus magnus. Posterior thoracic nerve. The second portion of the axillary artery lies beneath the Pectoralis minor. It is covered, in front, by the Pectoralis major and minor muscles; behind, it is sepa- rated from the Subscapularis by a cellular interval; on the inner side, it is in con- tact with the axillary vein. The brachial plexus of nerves surrounds the artery and separates it from direct contact with the vein and adjacent muscles. Relations of Second Portion of the Axillary Artery. In front. Pectoralis major and minor. Outer side. Brachial plexus. Inner side. Axillary vein. / Axillary 7 Artery. I Second \ Portion. Beh in d. Subscapularis. The third portion of the axillary artery lies beloAV the Pectoralis minor. It is in relation, in front, with the loAver border of the Pectoralis major above, being covered only by the integument and fascia below ; behind, with the loAver part of the Subscapularis, and the tendons of the Latissimus dorsi and Teres major; on its outer side, with the Coraco-brachialis; on its inner, or thoracic side, with the axillary vein. The brachial plexus of nerves bears the following relation to the artery in this part of its course : on the outer side is the median nerve, and the musculo-cutaneous for a short distance; on the inner side, the ulna, the internal, and lesser internal cutaneous nerves; and behind, the musculo-spiral, and cir- cumflex, the latter extending only to the lower border of the Subscapularis muscle. Relations of Third Portion of the Axillary Artery. In front. Integument and fascia. Pectoralis major. Outer side. Coraco-brachialis. Median nerve. Musculo-cutaneous nerve. Inner side. Ulnar nerve. Internal cutaneous nerves. Axillary vein. Beh in d. Scapularis. Tendons of Latissimus dorsi, and Teres major. Musculo-spiral, and circumflex nerves. Peculiarities. The axillary artery, in about one case out of every ten, gives off a large branch which forms either one of the arteries of the forearm, or a large muscular trunk. In the first set of cases this artery is most frequently the radial (1 in 33), sometimes the ulnar (1 in f>), and very rarely, the interosseous (1 in §06). In the second set of cases, the trunk gave origin to the subscapular, circumflex, and profunda arteries of the arm. Sometimes only one of the circumflex, or one of the profunda arteries, arose from the trunk, in these cases the brachial plexus surrounded the trunk of the branches, and not the main vessel. Surgical Anatomy. The student having carefully examined the relations of the axillary artery in its various parts, should now consider in what situation compression of this AXILLARY. 351 vessel may be most easily effected, and the best position for the application of a ligature to it when necessary. Compression of this vessel is required in the removal of tumors, or in amputation of the upper part of the arm; and the only situation in which this can be effectually made, is in the lower part of its course, just beneath the integument and fascia; and on com- pressing it from within outwards upon the humerus, the circulation may be efficiently suspended. The application of a, ligature to the axillary artery may be required, in cases of aneurism of the upper part of the brachial; and there are only two situations in which it may be secured, viz., in the upper, or in the lower part of its course. The axillary artery at its central part is so deeply seated, and, at the same time, so closely surrounded with large nervous truuks, that the application of a ligature to it would be almost impracticable. In the lower part of its course the operation is more simple, and may be performed in the following manner: The patient being placed on a bed, and the arm separated from the side, with the hand supinated, the bead of the humerus is felt for, and an incision made through the integument over it, about two inches in length, a little nearer to the posterior than the anterior fold of the axilla. After carefully dissecting through the areolar tissue and fascia, the median nerve and axillary vein are exposed; the former having been displaced to the outer, and the latter to the inner side of the arm, the elbow being at the same time bent so as to relax these structures, and facilitate their separation, the ligature may be passed around the artery from the ulnar to the radial side. The upper portion of the axillary artery may be tied, in cases of aneurism encroaching so far upwards that a ligature cannot be applied in the lower part of is course. Notwith- standing that this operation has been performed in some few cases, and with success, its performance is attended Avith much difficulty and danger. The student will remark, that in this situation, it would be necessary to divide a thick muscle, and, after separating the costo-coracoid membrane, the artery would be exposed at the bottom of a more or less deep space, with the cephalic and axillary veins in such relation with it as must render the application of a ligature to this part of the vessel particularly hazardous. Under such circumstances, it is an easier, and, at the same time, more advisable operation, to tie the subclavian artery in the third part of its course. In a case of wound of this vessel, the general practice of cutting down upon, and tying the vessel above and below the wounded point, should be adopted in all cases. The branches of the axillary artery are, the f Superior thoracic. From 1st Part, j Acromiai thoracic. j Thoracica longa. From 2d Part, j Thoracica alaris. {Subscapular. Anterior circumflex. Posterior circumflex. The Superior Thoracic is a small artery, which arises from the axillary, or by a common trunk Avith the acromial thoracic. Running forAvards and inAvards along the upper border of the Pectoralis minor, it passes between it and the Pec- toralis major to the side of the chest. It supplies these muscles, and the parietes of the thorax, anastomosing with the internal mammary and intercostal arteries. The Acromial Thoracic is a short trunk, Avhich arises from the forepart of the axillary artery. Projecting forwards to the upper border of the Pectoralis minor, it divides into three sets of branches, thoracic, acromial, and descending. The thoracic branches, tAvo or three in number, are distributed to the Serratus magnus and Pectoral muscle, anastomosing with the intercostal branches of the internal mammary. The acromial branches are directed outwards toAvards the acromion, supplyino* the Deltoid muscle, and anastomosing, on the surface of the acromion, with the suprascapular and posterior circumflex arteries. The descending branch 352 ARTERIES. passes in the interspace between the Pectoralis major and Deltoid, accompanying the cephalic vein, and supplying both muscles. The Long Thoracic passes downAvards and inAvards along the lower border of the Pectoralis minor to the side of the chest, supplying the Serratus magnus the Pectoral muscles, and mammary gland, and sending branches across the axilla to the axillary glands and Subscapularis, which anastomose Avith the internal mammary and intercostal arteries. The Thoracica Alar is is a small branch, which supplies the glands and areolar tissue of the axilla. Its place is frequently supplied by branches from some of the other Jhoracic arteries. The Subscapular, the largest branch of the axillary artery, arises opposite the lower border of the Subscapularis muscle, and passes doAvmvards and backAvards along its loAver margin to the inferior angle of the scapula, Avhere it anastomoses with the posterior scapular, a branch of the subclavian. It distributes branches to the Subscapularis, the Serratus magnus, Teres major, and Latissimus dorsi muscles, and gives off, about an inch and a half from its origin, a large branch, the dorsalis scapulae. This vessel curves round the inferior border of the scapula, leaving the axilla in the interspace between the Teres minor above, the Teres major beloAv, and the long head of the Triceps in front; and divides into three branches, a subscapular, which enters the subscapular fossa beneath the Subscapularis, which it supplies, anastomosing with the subscapular and suprascapular arteries ; an infraspinous branch (dorsalis scapulae), which turns round the axillary border of the scapula, between the Teres minor and the bone, enters the infraspinous fossa, supplies the Infraspinatus muscle, and anastomoses Avith the suprascapular and posterior scapular arteries; and a median branch, Avhich is continued along the axillary border of the scapula, betAveen the Teres major and minor, and, at the dorsal surface of the inferior angle of the bone, anastomoses Avith the suprascapular. The Circumflex Arteries Avind around the neck of the humerus. The Posterior, the larger of the tAvo, arises from the back part of the axillary, opposite the lower border of the Subscapularis muscle, and, passing backwards with the circumflex veins and nerve, through the quadrangular space bounded by the Teres major and minor, the scapular head of the Triceps and the humerus, winds around the neck of that bone, is distributed to the Deltoid muscle and shoulder joint, anastomosing with the anterior circumflex, suprascapular, and acromial thoracic arteries. The Anterior Circumflex, considerably smaller than the preceding, arises just below that vessel, from the outer side of the axillary artery. It passes horizon- tally outwards, beneath the Coraco-brachialis and short head of the Biceps, lying upon the_ forepart of the neck of the humerus, and, on reaching the bicipital groove, gives off an ascending branch, which passes upwards along it, to supplv the head of the bone and the shoulder joint. The trunk of the vessel is then continued outwards beneath the Deltoid, which it supplies, and anastomoses with the posterior circumflex, and acromial thoracic arteries. Brachial Artery (Fig. 200). The brachial artery commences at the lower margin of the tendon of the Teres major, and, passing down the inner and anterior aspect of the arm, terminates about half an inch below the bend of the elbow, where it divides into the radial and ulnar arteries. The direction of this vessel is marked by a line drawn from the outer side of the axillary space between the folds of the axilla, to a point midway between the condyles of the humerus, which corresponds to the depression along the inner border of the Coraco-brachialis and Biceps muscles. In the upper part BRACHIAL. 353 of its course, this vessel lies internal to the humerus; but below, it is in front of that bone. Relations. This artery is super- ficial throughout its entire extent, being covered, in front, by the in- tegument, the superficial and deep fasciae; the bicipital fascia separates it, opposite the elbow, from the me- dian basilic vein, the median nerve crosses it at its centre, and the ba- silic vein lies in the line of the ar- tery for the lower half of its course. Behind, it is separated from the inner side of the humerus above, by the long and inner head of the Tri- ceps, the musculo-spiral nerve and superior profunda artery interven- ing ; and from the front of the bone beloAv, by the insertion of the Co- raco-brachialis and the Brachialis anticus muscles. By its outer side, it is in relation with the commence- ment of the median nerve, and the Coraco-brachialis and Biceps mus- cles, wliich slightly overlap the ar- tery. By its inner side, with the internal cutaneous and ulnar nerves, its upper half; the median nerve, its loAver half. It is accompanied by two veins, the venae comites ; they lie in close contact with the artery, being connected together at intervals by short transverse com- municating branches. Fig. 200.—The Surgical Anatomy of the Brachial Artery. Plan or the Relations of the Brachial Artery. In front. Integument and fascite. Bicipital fascia, median basilic vein. Median nerve. Outer side. Median nerve. Coraco-brachialis. Biceps. Brachial Artery. Inner side. Internal cutaneous. Ulnar and median nerves. Behind. Triceps. Musculo-spiral nerve. Superior profunda artery. Coraco-brachialis. Brachialis anticus. Bend of the Elboav. At the bend of the elbow, the brachial artery sinks deeply into a triangular in- 354 ARTERIES. terval, the base of Avhich is directed upwards towards the humerus, and the sides of which are bounded, externally, by the Supinator longus, internally, by the Pro- nator radii teres; its floor is formed by the Brachialis anticus, and Supinator brevis. This space contains the brachial artery, Avith its accompanying veins, the radial and ulnar arteries, the median and musculo-spiral nerves, and the tendon of the Biceps. The brachial artery occupies the middle line of this space, and divides opposite the coronoid process of the ulna into the radial and ulnar arteries • it is covered, in front, by the integument, the superficial fascia, and the median basilic vein the vein being separated from direct contact Avith the artery by the bicipital fascia. Behind, it lies on the Brachialis anticus, Avhich separates it from the elboAv joint. The median nerve lies on the inner side of the artery, but separated from it below by an interval of half an inch. The tendon of the Biceps lies to the outer side of the space, and the musculo-spiral nerve still more externally, lying upon the Supinator brevis, and partly concealed by the Supinator longus. Peculiarities of the Artery as regards its Course. The Brachial artery, accompanied by the median nerve, may leave the inner border of the Biceps, and descend towards the inner con- dyle of the humerus, where it usually curves around a prominence of bone, to which it is connected by a fibrous band; it then inclines outwards, beneath or through the substance of the Pronator teres muscle, to the bend of the elbow. This variation bears considerable analogy with the normal condition of the artery in some of the carnivora. As regards its Division. Occasionally, the artery is divided for a short distance at its upper part into two trunks, which are united above and below. A similar peculiarity occurs in the main vessel of the lower limb. The point of bifurcation may be above or below the usual point, the former condition bein^ by far the most frequent. Out of 481 examinations recorded by Mr. Quain, some made on the_ right, and some on the left side of the body, in 386 the artery bifurcated in its normal position. In one case only was the place of division lower than usual, being two or three inches below the elbow joint. " In 94 cases out of 4S1, or about 1 in 5', there were two arteries instead of one in some part, or in the whole of the arm." There appears, however, to be no correspondence between the arteries of the two arms, with respect to their irregular division ; for in sixty-one bodies it occurred in one side only in forty-three; on both sides, in different positions, in thirteen ; on both sides, in the same position, in five. The point of bifurcation takes place at different parts of the arm, being most frequent in the upper part, less so in the lower part, and least so in the middle, the most usual point for the application of a ligature; under any of these circumstances two large arteries would be found in the arm instead of one. The most frequent (in three out of four) of these peculiarities is the high division of the radial. It often arises from the inner side of the brachial, and runs parallel with the main trunk to the elbow, where it crosses it lyino- beneath the fascia ; or it may perforate the fascia, and pass over the artery, immediately beneath the integument. The ulnar sometimes arises from the brachial high up, and then occasionally leaves that vessel at the lower part of the arm, and descends towards the inner condyle. In the fore- arm it generally lies beneath the deep fascia,.superficial to the Flexor muscles ; occasionally between the integument and deep fascia, and very rarely beneath the Flexor muscles. Ihe interosseous artery sometimes arises from the upper part of the brachial or axillary : as it descends the arm it lies behind the main trunk, and at the bend of the elbow regains its usual position. In some cases of high division of the radial, the remaining trunk (ulnar interosseous) oc- casionally passes, together with the median nerve, alon- the'inner margin of the arm to the inner condyle, and then passing from within outwards, beneath or throuo-h the Pronator teres, regains its usual position at the bend of the elbow. Occasionally, the two arteries representing the brachial are connected at the bend of the elbow by a short transverse branch, and are even sometimes reunited Sometimes long slender vessels, oasa aberrantia, connect the brachial or axillary arteries with one of the arteries of the forearm, or a branch from them. These vessels usually join tn.6 r&dicii. In some subjects the brachial artery is covered by an additional slip from the Biceps or Brachialis anticus muscles; and occasionally a slip from the latter muscle covers the whole extent of the ulnar interosseous trunk in cases of high division of the radial. Surgical Anatomy. Compression of the brachial artery is required in cases of amputation SURGICAL ANATOMY OF BRACHIAL ARTERY. 355 of the arm or forearm, in resection of the elbow joint, and the removal of tumors; and it will be observed that it may be effected in almost any part of its course; if pressure'is made in the upper part of the limb, it should be directed from within outwards, and if in the lower part, from before backwards, as the artery lies on the inner side of the humerus above, and in front of it below; The most favorable situation is either above or below the insertion of the Coraco-brachialis. The application of a ligature to the brachial artery may be required in cases of wounds of the vessel, or of aneurism of the brachial, the radial, ulnar, or interosseous arteries : and this vessel may be secured in any part of its course. The chief guides in determining its position are the surface-markings produced by the inner margin of the Coraco-brachialis and Biceps, the known course of the vessel, and its pulsation, which should be carefully felt for before any operation is performed, as the vessel occasionally deviates from its usual position in the arm. In whatever situation the operation is performed, great care is necessary on account of the extreme thinness of the parts covering the artery," and the intimate connection which the vessel has throughout its whole course with important nerves and veins. Sometimes a thin layer of muscular fibre is met with concealing the artery; if such is the case, it must be divided across, in order to expose it. In the upper third of the arm, the artery may be exposed in the following manner : The patient being placed horizontally upon a table, the affected limb should be raised from the side, and the hand supinated. An incision about two inches in length should be made on the ulnar side of the Coraco-brachialis muscle, and the subjacent fascia cautiously divided so as to avoid wounding the internal cutaneous nerve or basilic vein, which sometimes runs on the surface of the artery as high as the axilla. The fascia having been divided, it should be remembered, that the ulnar and internal cutaneous nerves lie on the inner side of the artery, the median on the outer side, the latter nerve being occasionally superficial to the artery in this situation, and that the venae comites are also in relation with the vessel, one on either side. These being care- fully separated, the aneurism-needle should be passed around the artery from the ulnar to the radial side. If two arteries are present in the arm in consequence of a high division, they are usually placed side by side; and if they are exposed in an operation, the surgeon should endeavor to ascertain, by alternately pressing on one or the other vessel, which of the two communicates with the wound or aneurism, when a ligature may be applied accordingly; or if pulsation or hemorrhage ceases only when both vessels are compressed, both vessels may be tied, as it may be concluded that the two communicate above the seat of disease, or are reunited. It should also be remembered, that two arteries may be present in the arm in a case of high division, and that one of these may be found along the inner intermuscular septum, in a line towards the inner condyle of the humerus, or in its usual position, but deeply placed, beneath the common trunk ; a knowledge of these facts will at once suggest the precautions necessary in every case, and indicate the necessary measure to be adopted when met with. In the middle of the arm the brachial artery may be exposed by making an incision along the inner margin of the Biceps muscle. The forearm being bent so as to relax the muscle, it should be drawn slightly aside, and the fasfia being carefully divided, the median nerve will be exposed lying upon the artery (sometimes beneath); this being drawn inwards and the muscle outwards, the artery should be separated from its accompanying veins and secured. In this situation the inferior profunda may be mistaken for the main trunk, especially if en- larged, from the collateral circulation having become established ; this may be avoided by directing the incision externally towards the Biceps, rather than inwards or backwards towards the Triceps. The lower part of the brachial artery is of extreme interest in a surgical point of view, on account of the relation which it bears to those veins most commonly opened in venesection. Of these vessels, the median basilic is the largest and most prominent, and, consequently, the one usually selected for the operation. It should be remembered that this vein runs parallel with the brachial artery, from which it is separated by the bicipital fascia, and that in no case should this vessel be selected for the operation, jexcept in a part which is not in contact with the artery. The branches of the brachial artery are the Superior profunda. Inferior profunda. Nutrient artery. Anastomotica magna. Muscular. The Superior Profunda arises from the inner and back part of the brachial, opposite the loAver border of the Teres major, and passes backAvards to the 356 ARTERIES. RaiHaUReeurrrtit interval betAveen the outer and inner heads of the Triceps muscle, accompanied by the musculo-spiral nerve; it Avinds around the back part of the shaft of the humerus in the spiral Fig. 201.—The Surgical Anatomy of the Radial and Ulnar groove, betAVCCll the Tl'i- Arteries* ceps and the bone, and descends on the outer side of the arm to the space betAveen the Brachialis an- ticus and Supinator longus, as far as the elboAv, where it anastomoses -with the re- current branch of the radial artery. It supplies the Deltoid, Coraco-brachialis, and Triceps muscles, and whilst in the groove, be- tAveen the Triceps and the bone, it gives off the poste- rior articular artery, Avhich descends perpendicularly betAveen the Triceps and the bone, to the back part of the elboAv joint, Avhere it anastomoses with the inter- osseous recurrent branch, and, on the inner side of the arm, with the ulnar recurrent, and with the anastomotica magna or infe- rior profunda (Fig. 203). The Nutrient artery of the shaft of the humerus arises from the brachial, about the middle of the arm. Passing downwards it en- ters the nutritious canal of that bone, near the inser- tion of the Coraco-brachia- lis muscle. The Inferior Profunda, of small size, arises from the brachial, a little below the middle of the arm; piercing the internal inter- muscular septum, it de- scends on the surface of the inner head of the Tri- ceps muscle, to the space betAveen the inner condyle and olecranon, accompa- nied by the ulnar nerve, and terminates by anasto- mosing with the posterior ulnar recurrent, and anas-, tomotica magna. The Anastomotica magna arises from the brachial, about two inches above the ■Dr^jj branch cf Ulnar Superficial** Vvh RADIAL. 357 elbow joint. It passes transversely inwards upon the Brachialis anticus, and piercing the internal intermuscular septum, winds around the back part of the humerus, between the Triceps and the bone, forming an arch above the olecranon fossa, by its junction with the posterior articular branch of the superior profunda. As this vessel lies on the Brachialis anticus, an offset passes betAveen the internal condyle and olecranon, Avhere it anastomoses with the inferior profunda and pos- terior ulnar recurrent arteries. Other branches ascend to join the inferior pro- funda ; and some descend in front of the inner condyle, to anastomose with the anterior ulnar recurrent. The Muscular are three or four large branches, which are distributed to the muscles in the course of the artery. They supply the Coraco-brachialis, Biceps, and Brachialis anticus muscles. Radial Artery. The Radial artery appears, from its direction, to be the continuation of the brachial, but, in size, it is smaller than the ulnar. It commences at the bifurca- tion of the brachial, just beloAv the bend of the elbow, and passes along the radial side of the forearm to the Avrist; it then winds backwards, round the outer side of the carpus, beneath the extensor tendons of the thumb, and, running forAvards, passes betAveen the two heads of the first Dorsal interosseous muscle, into the palm of the hand. It then crosses the metacarpal bones to the ulnar border of the hand, forming the deep palmar arch, and, at its termination, inosculates with the deep branch of the ulnar artery. The relations of this vessel may thus be con- veniently divided into three parts, viz., in front of the forearm, at the back of the wrist, and in the hand. Relations. In the forearm, this vessel extends from opposite the neck of the radius, to the forepart of the styloid process, being placed to the inner side of the shaft of that bone above, and in front of it below. It is superficial throughout its entire extent, being covered by the integument, the superficial and deep fasciae, and slightly overlapped superiorly by the Supinator longus. In its course downwards it lies upon the tendon of the Biceps, the Supinator brevis, the Pronator radii teres, radial origin of the Flexor sublimis digitorum, the Flexor longus pollicis. Pronator quadratus, and the loAver extremity of the radius. In the upper third of its course, it lies betAveen the Supinator longus and the Pronator radii teres; in its lower two-thirds, betAveen the tendons of the Supinator longus, and the Flexor carpi radialis. The radial nerve lies along the outer side of the artery, in the middle third of its course; and some filaments of the musculo-cutaneous nerve, after piercing the deep fascia, run along the lower part of the artery as it Avinds around the Avrist. The vessel is accompanied by venae comites throughout its whole course. Plan of the Relations of the Radial Artery in the Forearm. In front. Integument—superficial and deep fasciae. Supinator longus. Inner side. Radial \ Outer side. Pronator radii teres. Artery in j Supinator longus. Flexor carpi radialis. \ Forearm./ Radial nerve (middle third). Behind. Tendon of Biceps. Supinator brevis. Pronator radii teres. Flexor sublimis digitorum. Flexor longus pollicis. Pronator quadratus. Radius. At the wrist, as it Avinds around the outer side of the carpus, from the styloid 358 ARTERIES. process to the first interosseous space, it lies upon the external lateral ligament being covered by the extensor tendons of the thumb, subcutaneous veins, some filaments of the radial nerve, and the integument. It is accompanied by two veins, and a filament of the musculo-cutaneous nerve. In the hand, it passes from the upper end of the first interosseous space, between the heads of the Abductor indicis, transversely across the palm, to the base of the metacarpal bone of the little finger, Avhere it inosculates with the communicating branch from the ulnar artery, forming the deep palmar arch. R lies upon the carpal extremities of the metacarpal bones and the Interossei muscles, being covered by the flexor tendons of the fingers, the Lumbricales, the muscles of the little finger, and the Flexor brevis pollicis, and is accompanied by the deep branch of the ulnar nerve. Peculiarities. The origin of the radial artery varies in the proportion nearly of one in eight cases. In one case the origin was lower than usual. In the other cases, the upper part of the brachial was a more frequent source of origin than the axillary. The variations in the position of this vessel in the arm, and at the bend of the elbow, have been already mentioned. In the forearm it deviates less frequently from its position than the ulnar. It has been found lying over the fascia, instead of beneath it. It has also been observed on the surface of the Supinator longus, instead of along its inner border; and in turning round the wrist, it has been seen lying over, instead of beneath, the Extensor tendons. Surgical Anatomy. The operation of tying the radial artery is required in cases of wounds either of its trunk, or some of its branches, or for aneurism : and it will be observed, that the vessel may be easily exposed in any part of its course through the forearm. This opera- tion in the middle or inferior third of this region is easily performed; but in the upper third, near the elbow, the operation is attended with some difficulty, from the greater depth of the vessel, and from its being overlapped by the Supinator longus and Pronator teres muscles. To tie the artery in this situation, an incision three inches in length should be made through the integument, from the bend of the elbow obliquely downwards and outwards, on the radial side of the forearm, avoiding the branches of the median vein; the fascia of the arm being divided, and the Supinator longus drawn a little outwards, the artery will be exposed. The venae comites should be carefully separated from the vessel, and the ligature passed from the radial to the ulnar side. In the middle third of the forearm the artery may be exposed by making an incision of similar length on the inner margin of the Supinator longus. In this situation the radial nerve lies in close relation with the outer side of the artery, and should, as well as the veins, be carefully avoided. In the inferior third, the artery is easily secured by dividing the integument and fasciae in the interval between the tendons of the Supinator longus and Flexor carpi radialis muscles. The branches of the radial artery may be divided into three groups, corre- sponding with the three regions in which this vessel is situated. f Radial recurrent. In the J Muscular. Forearm. 1 Superficialis vohc. ^Anterior carpal. {Posterior carpal. Metacarpal Dorsales pollicis. Dorsalis indicis. f Princeps pollicis. J Radialis indicis. j Perforantes. (^Interossei. The Radial Recurrent is given off immediately below the elboAv. It ascends be- tAveen the branches of the musculo-spiral nerve, lying on the Supinator brevis, and then between the Supinator longus and Brachialis anticus, supplying these muscles, the elbow joint, and anastomosing Avith the terminal branches of the superior profunda. Hand. BRANCHES OF RADIAL. 359 Fit 202.—Ulnar and Radial Arteries. Deep View. Anterior Ulnar Ri cur rent The Muscular Branches are distributed to the muscles on the radial side of the forearm. The Superficialis Voice arises from the radial artery, just where this vessel is about to wind around the Avrist. Running forAvards, it passes betAveen the muscles of the thumb, which it supplies, and anastomoses with the termination of the ulnar artery, completing the superficial palmar arch. This vessel varies considerably in size; usually it is very small, and terminates in the muscles of the thumb; some- times it is as large as the continuation of the radial. The carpal branches supply the joints of the wrist. The Anterior Carped is a small vessel, which arises from the radial artery near the lower border of the Pro- nator quadratus, and running in- wards in front of the radius, anas- tomoses with the anterior carpal branch of the ulnar, artery. From the arch thus formed, branches descend to supply the articulations of the wrist. The Posterior Carpal is a small vessel, which arises from the radial artery beneath the extensor tendons of the thumb ; crossing the carpus transversely to the inner border of the hand, it anastomoses with the posterior carpal branch of the ulnar. Superiorly it sends branches up- wards, which anastomose with the termination of the anterior inter- osseous artery. Other branches descend to the metacarpal spaces ; they are the dorsal interosseous ar- teries for the third and fourth in- terosseous spaces; they anastomose with the posterior perforating branches from the deep palmar arch. The Metacarpal (First Dorsal Interosseous Branch) arises beneath the extensor tendons of the thumb, sometimes with the posterior carpal artery; running forwards on the second dorsal interosseous muscle; it communicates, behind, with the corresponding perforating branch of the deep palmar arch; and, in front, inosculates with the digital branch of the superficial palmar arch, and supplies the adjoining sides of the index and middle fingers. The Dor sales Pollicis are two small vessels, A\Thich run along the sides of the dorsal aspect of the thumb. They sometimes arise se- parately, or occasionally by a com- mon trunk, near the base of the first metacarpal bone. The Dorsalis Indicis, also a small branch, runs along the radial h of Ulnar 360 ARTERIES. side of the back of the index finger, sending a few branches to the Abductor indicis. The Princejjs Pollicis arises from the radial just as it turns inAvards to the deep part of the hand; it descends between the Abductor indicis and Adductor pollicis, along the ulnar side of the metacarpal bone of the thumb, to the base of the first phalanx, where it divides into two branches, which run along the sides of the palmar aspect of the thumb, and form an arch on the under surface of the last phalanx, from which branches are distributed to the integument and cellular mem- brane of the thumb. The Radialis Indicis arises close to the preceding, descends betAveen the Ab- ductor indicis and Adductor pollicis, and runs along the radial side of the index finger to its extremity, where it anastomoses Avith the collateral digital artery from the superficial palmar arch. At the lower border of the Adductor pollicis this vessel anastomoses with the princeps pollicis, and gives a communicating branch to the superficial palmar arch. The Perforantes, three in number, pass backwards betAveen the heads of the last three Dorsal interossei muscles, to inosculate Avith the dorsal interosseous arteries. The Palmar Interossea, three or four in number, are branches of the deep palmar arch; they run forAvards upon the Interossei muscles, and anastomose at the clefts of the fingers with the digital branches of the superficial arch. Ulnar Artery. The Ulnar Artery, the larger of the two subdivisions of the brachial, com- mences a little below the bend of the elbow, and crosses the inner side of the fore- arm obliquely to the commencement of its loAver half; it then runs along its ulnar side to the Avrist, crosses the annular ligament on the radial side of the pisiform bone, and passes across the palm of the hand, forming the superficial palmar arch, which terminates by inosculating with the superficialis volae. Relations in the Forearm. In its upper half, it is deeply seated, being covered by all the superficial flexor muscles, excepting the Flexor carpi ulnaris; crossed by the median nerve, which, at its origin, for about an inch lies to its inner side; and it lies upon the Brachialis anticus and Flexor profundus digitorum muscles. In the lower half of the forearm, it lies upon the Flexor profundus, being covered by the integument, the superficial and deep fasciae, and is placed betAveen the Flexor carpi ulnaris and Flexor sublimis digitorum muscles. It is accompanied by two veins, which lie one on each side of the vessel; the ulnar nerve lies on its inner side for the loAver two-thirds of its extent, and a small branch from it de- scends on the lower part of the vessel to the palm of the hand. Plan of Relations of the Ulnar Artery in the Forearm. In font. Superficial flexor muscles. j „ h&]f Median nerve. j rr Superficial and deep fasciae. Lower half. Inner side. Ulnar \ Outer side. Flexor carpi ulnaris. Aiteiy in , Flexor sublimis digitorum. Ulnar nerve (lower two-thirds). Forearm. / Behind. Brachialis anticus. Flexor profundus digitorum. At the wrist, the ulnar artery is covered by the integument and fascia, and lies upon the anterior annular ligament. On its inner side is the pisiform bone. The ulnar nerve lies at the inner side, and somewhat behind the artery. ULNAR. 361 In the palm of the hand, the continuation of the ulnar artery is called the super- ficial palmar arch; it passes obliquely outwards to the interspace betAveen the ball of the thumb and the index finger, where it anastomoses with the superficialis vola?, and a branch from the radialis indicis, thus completing the superficial palmar arch. The convexity of this arch is directed towards the fingers, its concavity towards the muscles of the thumb. The superficial palmar arch is covered by the Palmaris brevds, the palmar fascia, and integument; and lies upon the annular ligament, the muscles of the little finger, the tendons of the superficial Flexor,, and the divisions of the median and ulnar nerves, the latter accompanying the artery a short part of its course. Relations of the Superficial Palmar Arch. In front. /' Behind. Integument. / Ulnar Annular ligament. Palmaris brevis. I Artery in i Origin of muscles of little finger. Palmar fascia. V Hand. J Superficial flexor tendons. \^_^y Division of median and ulnar nerves. Peculiarities. The ulnar artery was found to vary in its origin nearly in the proportion of one in thirteen cases, in one case arising lower than usual, about two or three inches below the elbow, and in all the other cases much higher, the brachial being a more frequent source of origin than the axillary. Variations in the positiofi of this vessel are more frequent than in the radial. When its origin is normal, the course of the vessel is rarely changed. When it arises high up, its position in the forearm is almost invariably superficial to the Flexor muscles, lying commonly beneath the fascia, more rarely between the fascia and integument. In a few cases, its posi- tion was subcutaneous in the upper part of the forearm, subaponeurotic in the lower part. Surgical Anatomy. The application of a ligature to this vessel is required in cases of wound of the artery, or of its branches, or in consequence of aneurism. In the upper half of the forearm, the artery is deeply seated beneath the superficial Flexor muscles, and their division would be requisite in a case of recent wound of the artery in this situation, in order to secure it, but under no other circumstances. In the middle and inferior thirds of the forearm, this vessel may be easily secured by making an incision on the radial side of the tendon of the Flexor carpi ulnaris; the deep fascia being divided, and the Flexor carpi ulnaris and its companion muscle, the Flexor sublimis, being separated from each other, the vessel will be exposed, accompanied by its venae comites, the ulnar nerve lying on its inner side. The veins being separated from the artery, the ligature should be passed from its ulnar to its radial side, taking care to avoid the ulnar nerve. The branches of the ulnar artery may be arranged into three groups, Fo Anterior ulnar recurrent. Posterior ulnar recurrent. T A f Anterior interosseous. Interosseous < -d . • • , ( Posterior interosseous. Muscular. ■nr,,\f j Anterior carpal. \ Posterior carpal. tt i j Deep or communicating branch. [ Digital. The Anterior Ulnar Recurrent arises immediately beloAv the elboAv joint, passes upwards and inAvards betAveen the Brachialis anticus and Pronator radii teres, sup- plies these muscles, and, in front of the inner condyle, anastomoses with the anastomotica magna and inferior profunda. The Posterior Ulnar Recurrent is much larger, and arises someAvhat loAver than the preceding. It passes backAvards and inAvards, beneath the Flexor sublimis, and ascends behind the inner condyle of the humerus. In the interval between 362 ARTERIES. this eminenee and the olecranon, it lies beneath the Flexor carpi ulnaris ascend- ing betAveen the heads of that muscle, beneath the ulnar nerve ; it supplies the neighboring muscles and joint, and anastomoses Avith the inferior profunda anasto- motica magna, and interosseous recurrent arteries. The Interosseous Artery is a short trunk, about an inch in length, and of con- siderable size, which arises immediately below the bicipital tuberosity of the radius and, passing backAvards to the upper border of the interosseous membrane divides into two branches, the anterior and posterior interosseous. The Anterior Interosseous Fig. 203.—Arteries of the Back of the Forearm and Hand. passes doAVn the forearm on the anterior surface of the interosseous membrane, to Avhich it is connected by a thin aponeurotic arch. It is accompanied by the in- terosseous branch of. the median nerve, and over- lapped by the contiguous margins of the Flexor pro- fundus digitorum and Flexor longus pollicis ■ muscles, giving off in this situation muscular branches, and the nutrient arteries of the ra- dius and ulna. At the up- per border of the Pronator quadratus, a branch descends in front of that muscle, to anastomose in front of the carpus Avith the branches from the anterior carpal and deep palmar arch. The con- tinuation of the artery passes behind the Pronator qua- dratus, and, piercing the in- terosseous membrane, de- scends to the back of the Avrist, where it anastomoses Avith the posterior carpal branches of the radial and ulnar arteries. The anterior interosseous gives off a long, slender branch, Avhich ac- companies the median nerve, and gives offsets to its sub- stance. This, the median artery, is sometimes much enlarged. The Posterior Interos- seous Artery passes back- wards through the interval between the oblique liga- ment and the upper border of the interosseous mem- brane, and passes doAvn the back part of the forearm, betAveen the superficial and j os ferf or THORACIC AORTA. 363 deep layer of muscles, to both of which it distributes branches. Descending to the back of the wrist, it anastomoses with the termination of the anterior interosseous and with the posterior carpal branches of the radial and ulnar arteries. 11ns artery gives off, near its origin, the posterior interosseous recur- rent branch a arge vessel, which ascends to the interval between the external condyle and olecranon, beneath the Anconeus and Supinator brevis, anasto- mosing with a branch from the superior profunda, and with the posterior ulnar recurrent arteries. The Muscular Branches are distributed to the muscles along the ulnar side of the forearm. The Carpal^ Branches are intended for the supply of the wrist joint. The Anterior Carpal is a small vessel, which crosses the anterior surface of the carpus beneath the tendons of the Flexor profundus, and inosculates Avith a corresponding branch of the radial artery. The Posterior Carped arises immediately above the pisiform bone, winding backwards beneath the tendon of the Flexor carpi ulnaris; it gives off a branch which passes across the dorsal surface of the carpus beneath the extensor tendons anastomosing with a corresponding branch of the radial artery, and forming the posterior carpal arch; it is then continued along the metacarpal bone of the little finger, forming its dorsal branch. The Deep or Communicating Branch arises at the commencement of the palmar arch, passing deeply inwards between the Abductor minimi digiti and Flexor brevis minimi digiti, near their origins; it anastomoses with the termination of the radial artery, completing the deep palmar arch. The Digital Branches, four in number, are given off from the convexity of the superficial palmar arch. They supply the ulnar side of the little finger/and the adjoining sides of the ring, middle, and index fingers; the radial side of the index finger and thumb being supplied from the radial artery. The digital arteries at first lie superficial to the flexor tendons, but as they pass forwards with the digital nerves to the clefts between the fingers, they lie between them, and are there joined by the interosseous branches from the deep palmar arch. The digital arteries on the sides of the fingers lie beneath the digital nerves; and, about the middle of the last phalanx, the tAvo branches for each finger form an arch, from the convexity of which branches pass to supply the matrix of the nail. The Descending Aorta. The descending aorta is divided into tAvo portions, the thoracic and abdominal, in correspondence with the two great cavities of the trunk in Avhich it is situated. The Thoracic Aorta commences at the lower border of the third dorsal vertebra, on the left side, and terminates at the aortic opening in the Diaphragm in front of the last dorsal vertebra. At its commencement, it is situated on the left side of the spine; it approaches the median line as it descends, and, at its termination, lies directly in front of the column. The direction of this vessel being influenced by the spine, upon which it rests, it is concave forAvards in the dorsal region, and, as the branches given off from it are small, the diminu- tion in the size of the vessel is inconsiderable. It is contained in the back part of the posterior mediastinum, being in relation in front, from above doAvmvards, WltIa the left pulmonary artery, the left bronchus, the pericardium, and the cesophagus; behind, Avith the vertebral column, and the vena azygos minor; on the right side, with the vena azygos major, and thoracic duct; on the left side, with the left pleura and lung. The oesophagus, with its accompanying nerves, hes on the right side of the aorta above; in front of this vessel, in the middle of its course; whilst, at its lower part, it is on the left side, on a plane anterior to it. 361 ARTERIES. Plan of the Relations of the Thoracic Aorta. Right side. (Esophagus (above). Vena azygos major. Thoracic duct. Surgical Anatomy. The student should now consider the effects likely to be produced by aneurism of the thoracic aorta, a disease of common occurrence. When we consider the great depth of the vessel from the surface, and the number of important structures which surround it on every side, it may be easily conceived what a variety of obscure symptoms may arise, from disease of this part of the arterial system, and how they may be liable to be mistaken for those of other affections. Aneurism of the thoracic aorta most usually extends backwards, along the left side of the spine, producing absorption of the bodies of the vertebrae, causing extensive curvature of the spine; whilst the irritation or pressure on the cord, will give rise to pain, either in the chest, back, or loins, with radiating pain in the left upper intercostal spaces, from pressure on the intorcostal nerves; at the same time the tumor may project on each side of the spine, beneath the integument, as a pulsating swelling, simulating abscess connected with diseased bone; or it may displace the oesophagus, and compress the lung on one or the other side. If the tumor extend forward, it may press upon and displace the heart, giving rise to palpitation, and other symptoms of disease of that organ; or it may displace, or even compress, the oesophagus, causing pain and difficulty of swallowing, as in stricture of that tube, and ultimately even open into it by ulceration, producing fatal hemorrhage. If the disease make Avay to either side, it may press upon the thoracic duct; or it may burst into the pleural cavity, or into the trachea or lung; and lastly, it may open into the posterior mediastinum. Branches of the Thoracic Aorta. Pericardiac. (Esophageal. Bronchial. Posterior mediastinal. Intercostal. The Pericardiac are a few small vessels, irregular in their origin, distributed to the pericardium. The Bronchial Arteries are the nutrient vessels of the lungs, and vary in number, size, and origin. That of the right side arises from the first aortic inter- costal, or by a common trunk Avith the left bronchial, from the anterior part of the thoracic aorta. Those of the left side, usually two in number, arise from the thoracic aorta, one a little lower than the other. Each vessel is directed forwards to the back part of the corresponding bronchus, along Avhich they run, dividing and subdividing, upon the bronchial tubes; supplying them, the cellular tissue of the lungs, the bronchial glands, and the oesophagus. The (Esophageal Arteries, usually four or five in number, arise from the anterior part of the aorta, and pass obliquely doAvnAvards to the oesophagus, form- ing a chain of anastomoses along that tube, anastomosing with the oesophageal branches of the inferior thyroid arteries above, and with ascending branches from the phrenic and gastric arteries below. The Posterior Mediastinal Arteries are numerous small vessels which supply the glands and loose areolar tissue in the mediastinum. In front. Left pulmonary an Left bronchus. Pericardium. (Esophagus. Vertebral column Vena azygos mim Left side. Pleura. Left Lung. (Esophagus (below). ABDOMINAL AORTA. 365 The Intercostal Arteries arise from the posterior part of the aorta. They are usually ten in number on each side, the superior intercostal space (and occasion- ally the second one) being supplied by the superior intercostal, a branch of the subclavian. The right intercostals are longer than the left, on account of the position of the aorta to the left side of the spine. They pass outwards, across the bodies of the vertebrae, to the intercostal spaces, being covered by the pleura, and crossed by the oesophagus, thoracic duct, sympathetic nerve, and the vena azygos major, the left passing beneath the superior intercostal vein, the vena azygos minor, and sympathetic. In the intercostal spaces each artery divides into two branches, an anterior, or proper intercostal branch, AAhich passes out- wards ; and a posterior, or dorsal branch, Avhich passes backAvards. The anterior branch passes outAvards, at first lying upon the External intercostal muscle, covered in front by the pleura and a thin fascia. It then passes betAveen the two layers of Intercostal muscles, and, having ascended obliquely to the loAver border of the rib above, divides, near the angle of that bone, into tAvo branches ; of these, the larger runs in the groove on the loAver border of the rib above; the smaller branch along the upper border of the rib beloAV ; passing forward, they supply the Intercostal muscles, and anastomose Avith the anterior intercostal arteries, branches of the internal mammary, and Avith the thoracic branches of the axillary artery. The first aortic intercostal anastomoses Avith the superior intercostal, and the last three pass between the abdominal muscles, inosculating in front Avith the epigastric, and with the phrenic and lumbar arteries. Each intercostal artery is accompanied by a vein and nerve, the former being above, and the latter beloAv, except in the upper intercostal spaces, where the nerve is at first above the artery. The arteries are protected from pressure during the action of the In- tercostal muscles, by fibrous arches thrown across, and attached by each extremity to the bone. The Posterior, or Dorsal Branch, of each intercostal artery, passes backAvards to the inner side of the anterior costo-transverse ligament, and divides into a spinal branch, Avhich supplies the vertebrae, the spinal cord and its membranes, and a muscular branch, which is distributed to the muscles and integument of the back. The Abdominal Aorta (Fig. 204). The Abdominal Aorta commences at the aortic opening of the Diaphragm, in front of the body of the last dorsal vertebra, and descending a little to the left side of the vertebral column, terminates on the left side of the body of the fourth lumbar vertebra, where it divides into the two common iliac arteries. As it lies upon the bodies of the vertebrae, it is convex forAvards, the greatest convexity corresponding to the third lumbar vertebra, Avhich is a little above and to the left side of the umbilicus. Relations. It is covered, in front, by the lesser omentum and stomach, behind Avhich are the branches of the coeliac axis and the solar plexus ; below these, by the splenic vein, the pancreas, the left renal vein, the transverse portion of the duodenum, the mesentery, and aortic plexus. Behind, it is separated from the lumbar vertebrae by the left lumbar veins, the receptaculum chyli, and thoracic duct. On the right side, Avith the inferior vena cava (the right crus of the Diaphragm being interposed above), the vena azygos, thoracic duct, and right semilunar ganglion. On the left side, Avith the sympathetic nerve and left semi- lunar ganglion. 366 ARTERIES. Plan of the Relations of the Abdominal Aorta. In fron t. Lesser omentum and stomach. Branches of cceliac axis and solar plexus. Splenic vein. Pancreas. Right side. Right crus of diaphragm. Inferior vena cava. Vena azygos. Thoracic duct. Right semilunar ganglion. Behind. Left lumbar veins. Receptaculum chyli. Left renal vein. Transverse duodenum. Mesentery. Aortic plexus. Left side. Sympathetic nerve. Left semilunar ganglion. Thoracic duct. Vertebral column. Fig. 204.—The Abdominal Aorta and its Branches. CtELIAC AXIS. 367 Surgical Anatomy. ^ Aneurisms of the abdominal aorta near the coeliac axis communicate in nearly equal proportion with the anterior and posterior parts of this vessel. When an aneurismal sac is connected with the back part of the aorta, it usually produces absorption of the bodies of the vertebrae, and forms a pulsating tumor, that presents itself in the left hypochondriac or epigastric regions, accompanied by symptoms of disturbance of the alimentarycanal. Pain is invariably present, and is usually of two kinds, a fixed and con- stant pain in the back, caused by the tumor pressing on or displacing the branches of the solar plexus and splanchnic nerves, and a sharp lancinating pain, radiating along those branches of the lumbar nerves pressed on by the tumor; hence the pain in0the loins, the testes, the hypogastrium, and in the lower limb (usually of the left side). This form of aneurism usually bursts into the peritoneal cavity, or behind the perjtoneum, in the left hypo- chondriac region; or it may form a large aneurismal sac, extending down as low as Poupart's ligament;_ hemorrhage in these cases being generally very extensive, but slowly produced, and never rapidly fatal. When an aneurismal sac is connected with the front of the aorta near the coeliac axis, it forms a pulsating tumor in the left hypochondriac or epigastric regions, usually attended with symptom^ of disturbance of the alimentary canal, as sickness, dyspepsia, or constipation, and accompanied by pain, which is constant but nearly always fixed in the loins, epigastrium, or some part of the abdomen; the radiating pain being rare, as the lumbar nerves are seldom implicated. This form of aneurism may burst into the peritoneal cavity, or behind the peri- toneum, between the layers of the mesentery, or, more rarely, into the duodenum; it rarely exteuds backwards so as to affect the spine. Branches of the Abdominal Aorta. Phrenic. (Gastric. Renal. Coeliac axis Z. Hepatic. Spermatic. ( Splenic. Inferior mesenteric. Superior mesenteric. Lumbar. Suprarenal. Sacra media. The branches may be divided into tAvo sets : 1. Those supplying the viscera. 2. Those distributed to the walls of the abdomen. Visceral Branches. . Parietal Branches. Supplying f . . / gastric. Phrenic. visr-Prn I Vobh&c axis- \ Hepatic. Lumbar. •< (Splenic. Sacra media. Superior mesenteric. ^ Inferior mesenteric. Suprarenal glands. Suprarenal. Kidneys. Renal. Testes. Spermatic. Cceliac Axis. To expose this artery, raise the liver, draw upon the stomach, and then tear through the layers of the lesser omentum. It is a short thick trunk, about half an inch in length, arising from the aorta, opposite the margin of the Diaphragm, and passing nearly horizontally forwards (in the erect posture), divides into three large branches, the gastric, hepatic, and splenic, occasionally giving off one of the phrenic arteries. Relations. It is covered, in front, by the lesser omentum. On the right side, it is in relation with the right semilunar ganglion, and the lobus Spigelii of the liver. On the left side, Avith the left semilunar ganglion and cardiac end of the stomach. Below, it rests upon the upper border of the pancreas. The Gastric Artery (Coronaria ventriculi), the smallest of the three branches of the cceliac axis, passes upwards and to the left side, to the cardiac orifice of the stomach, distributing branches to the oesophagus, which anastomose with the aortic oesophageal arteries; others supply the cardiac end of the stomach, inoscu- lating with branches of the splenic artery: it then passes from left to right, along the lesser curvature of the stomach to the pylorus, lying in its course between the layers of the lesser, omentum, and giving branches to'both surfaces of the organ; at its termination it anastomoses with the pyloric branch of the hepatic. A'iscera of digestion. 368 ARTERIES. The Hepatic Artery in the adult is intermediate in size betAveen the gastric and splenic; in the foetus, it is the largest of the three branches of the coeliac axis. It passes upAvards to the right side, between the layers of the lesser omen- tum, and in front of the foramen of WinsloAV, to the transverse fissure of the liver where it divides into two branches (right and left), Avhich supply the corresponding lobes of that organ, accompanying the ramifications of the vena portae and hepatic duct. The hepatic artery, in its course along the right border of the lesser omen- tum, is in relation Avith the ductus communis choledoclms and portal vein, the former lying to the right of the artery, and the vena portae behind. Its branches are the Pyloric. Gastro-duodenalis. ( gastro-epiploica dextra. ( .rancreatico-duodenalis. ' Cystic. The Pyloric Branch arises from the hepatic, above the pylorus, descends to the Fig. 205.—The Cceliac Axis and its Branches, the Liver having been taised, and the Lesser Omentum removed. pyloric end of the stomach; and passes from right to left along its lesser curvature, supplying it with branches, and inosculating with the gastric artery. ihe Gastro-duodenalis is a short but large branch, which descends behind the duodenum, near the pylorus, and divides at the lower border of the stomach into two branches, the gastro-epiploica dextra and the pancreatico-duodenalis. BRANCHES OF C(ELIAC AXIS. 369 Previous to its division, it gives off two or three small inferior pyloric branches to the pyloric end of the stomach and pancreas. The Gastro-epiphica Dextra runs from right to left along the greater curva- ture of the stomach, between the layers of the great omentum, anastomosing about the middle of the lower border of this organ, with the gastro-epiploica "sinistra from the splenic artery. This vessel gives off numerous branches, some of which ascend to supply both surfaces of the stomach, whilst others descend to supplv the great omentum. FF J The Pancreatico-duodenalis descends along the contiguous margins of the duo- denum and pancreas. It supplies both these organs, and anastomoses with the in- ferior pancreatico-duodenal branch of the superior mesenteric artery. In ulceration of the duodenum, which frequently occurs in connection with severe burns, this artery is often involved, and death may occur from sudden hemorrhage into the intestinal canal. Fig. 206.—The Cceliac Axis and its Branches, the Stomach having been raised, and the Transverse Mesocolon removed. The Cystic Artery, usually a branch of the right hepatic, passes upwards and for- ^vards along the neck of the gall-bladder, and divides into two branches, one of which ramifies on its free surface, the other, between it and the substance of the liver. The Splenic Artery, in the adult, is the largest of the three branches of the coeliac axis, and is remarkable for the extreme tortuosity of its course. It passes horizontally to the left side behind the upper border of the pancreas, accompanied 26 370 ARTERIES. by the splenic vein, which lies below it; and on arriving near the spleen, divides into branches, some of which enter the hilus of that organ to be distributed to its structure, Avhilst others are distributed to the great end of the stomach. The branches of this vessel are : Pancreaticae parvre. Gastric (Vasa brevia). Pancreatica magna. Gastro-epiploica sinistra. The Pancreatic are numerous small branches derived from the splenic as it runs behind the upper border of the pancreas, supplying its middle and left parts. One of these, larger than the rest, is given off from the splenic near the left extremity of the pancreas; it runs from left to right near the posterior surface of the gland following the course of the pancreatic duct, and is called the pancreatica magna. These vessels anastomose with the pancreatic branches of the pancreatico-duodenai arteries. The Gastric (Vasa brevia) consist of from five to seven small branches, which arise either from the termination of the splenic artery, or from its terminal branches ; and passing from left to right, between the layers of the gastro-splenic omentum, are distributed to the great curvature of the stomach, anastomosing with branches of the gastric and gastro-epiploica sinistra arteries. The Gastro-epiploica Sinistra, the largest branch of the splenic, runs from left to right along the great curvature of the stomach, betAveen the layers of the great omentum ; and anastomoses with the gastro-epiploica dextra. In its course, it distributes several branches to the stomach, which ascend upon both surfaces; others descend to supply the omentum. Superior Mesenteric Artery. In order to expose this vessel, raise the great omentum and transverse colon, draw down the small intestines, and if the peritoneum is divided where the transverse mesocolon and mesentery join, this artery will be exposed just as it issues beneath the lower border of the pancreas. The Superior Mesenteric Artery (Fig. 207) supplies the whole length of the small intestine, except the first part of the duodenum ; it also supplies the crecum, ascending and transverse colon; it is a vessel of large size arising from the forepart of the aorta, about a quarter of an inch below the cceliac axis; being covered, at it? origin, by the splenic vein and pancreas. It passes forwards, between the pancreas and transverse portion of the duodenum, crosses in front of this portion of the intes- tine, and descends between the layers of the mesentery to the right iliac fossa, where it terminates, considerably diminished in size. In its course it forms an arch, the convexity being directed forwards and downwards to the left side, the concavity backwards and upwards to the right. It is accompanied by the superior mesen- teric vein, and surrounded by the superior mesenteric plexus of nerves. Its branches are the Inferior pancreatico-duodenai. Ileo-colic. Vasa intestini tenuis. _ Colica dextra. Colica media. The Inferior Pancreatico-duodenai is given off from the superior mesenteric below the pancreas, and is distributed to its right extremity and the transverse and descending portions of the duodenum, anastomosing with the pancreatico-duo- denai artery. The Vasa Intestini Tenuis arise from the convex side of the superior mesenteric artery. Ihey are usually from twelve to fifteen in number, and are distributed to the jejunum and ileum. They run parallel with one another between the layers of the mesentery ; each vessel dividing into two branches, which unite with similar branches on each side, forming a series of arches, the convexities of which are directed towards the intestine. From this first set of arches branches arise, which again unite with similar branches from either side, and thus a second series of arches is formed; and from these latter, a third, and even a fourth or fifth series SUPERIOR MESENTERIC. 371 of arches are constituted, diminishing in size the nearer they approach the intes- tine. From the terminal arches numerous small straight vessels arise Avhich encircle the intestine, upon Avhich they are minutely distributed, ramifying between its coats. The Jlco-colic Artery is the lowest branch given off from the concavity of the superior mesenteric artery. It descends between the layers of the mesentery to the right iliac fossa, where it divides into tAvo branches. Of these, the inferior one inosculates Avith the loAvest branches of the vasa intestini tenuis, from the con- vexity of which branches proceed to supply the termination of the ileum, the caecum and appendix caeci, and the ileo-caecal and ileo-colic valves. The superior division inosculates with the colica dextra, and supplies the commencement of the colon. Fig. 207.—The Superior Mesenteric Artery and its Branches. The Colica Dextra arises from about the middle of the concavity of the supe- rior mesenteric artery, and passing beneath the peritoneum to the middle of the ascending colon, divides into two branches ; a descending branch, Avhich inoscu- lates with the ileo-colic ; and an ascending branch, which anastomoses with the colica media. These branches form arches, from the convexity of Avhich vessels are distributed to the ascending colon. The branches of this vessel are covered with peritoneum only on their anterior aspect. The Culiea Media arises from the upper part of the concavity of the superior mesenteric, and, passing forAvards betAveen the layers of the transverse meso-colon, 372 ARTERIES. divides into tAvo branches; the one on the right side inosculating with the colica dextra; that on the left side Avith the colica sinistra, a branch of the' inferior mesenteric. From the arches formed by their inosculation, branches are distributed to the transverse colon. The branches of this vessel lie betAveen two layers of peritoneum. Fig. 208.—The Inferior Mesenteric Artery and its Branches. Inferior Mesenteric Artery. In order to expose this vessel, draw the small intestines and mesentery over to the right side of the abdomen, raise the transverse colon towards the thorax, and divide the perito- neum covering the left side of the aorta. The Inferior Mesenteric Artery (Fig. 208) supplies the descending and sigmoid flexure of the colon, and greater part of the rectum. It is smaller than the supe- rior mesenteric; and arises from the left side of the aorta, between one and two inches above its division into the common iliacs. It passes dowmvards to the left iliac fossa, and then descends, between the layers of the mesorectum, into the pelvis, under the name of the superior hemorrhoidal artery. It lies at first in close relation with the left side of the aorta, and then passes in front of the left common iliac artery. Its branches are the Colica sinistra. Sigmoidea. Superior hemorrhoidal. The Colica Sinistra passes behind the peritoneum, in front of the left kidney, to reach the descending colon, and divides into two branches; an ascending branch, INFERIOR MESENTERIC. 373 which inosculates Avith the colica media; and a descending branch, which anasto- moses with the sigmoid artery. From the arches formed by these inosculations, branches are distributed to the descending colon. The Sigmoid Artery runs obliquely downwards across the Psoas muscle to the sigmoid flexure of the colon, and divides into branches which supply this part of the intestine; anastomosing above, with the colica sinistra ; and below, with the superior hemorrhoidal artery. This vessel is sometimes replaced by three or four small branches. The Superior Hemorrhoidal Artery, the continuation of the inferior mesen- teric, descends into the pelvis between the layers of the mesorectum, crossing, in its course, the ureter, and left common iliac artery and vein. Opposite the middle of the sacrum it divides into two branches, which descend one on each side of the rectum, where they divide into several small branches, which are distributed between the mucous and muscular coats of this tube, to near its lower end; anas- tomosing with^ each other, with the middle hemorrhoidal arteries, branches of the internal iliac, and with the inferior hemorrhoidal branches of the internal pudic. The student should especially remark, that the trunk of this vessel descends along the back part of the intestine as far as the middle of the sacrum before it divides ; this is about a finger's length or four inches from the anus. In disease of this tube, the rectum should never be divided beyond this point in that direction, for fear of involving this artery. The Suprarenal Arteries are two small vessels, which arise, one on each side of the aorta, opposite the superior mesenteric artery. They pass obliquely up- Avards and outAvards, to the under surface of the suprarenal capsules, to which they are distributed, anastomosing with capsular branches from the phrenic and renal arteries. In the adult these arteries are of small size; in the foetus they are as large as the renal arteries. The Renal Arteries are two large trunks, Avhich arise from the sides of the aorta, immediately below the superior mesenteric artery. Each is directed out- wards, so as to form nearly a right angle Avith the aorta. The right one, longer than the left, on account of the position of the aorta, passes behind the inferior vena cava. The left is someAvhat higher than the right. Previously to entering the kidney, each artery divides into four or .five branches, Avhich are distributed to its substance. At the hilus, these branches lie betAveen the renal vein and ureter, the vein being usually in front, the ureter behind. Each vessel gives off some small branches to the suprarenal capsules, the ureter, and to the surrounding cellular membrane and muscles. The Spermatic Arteries are distributed to the testes in the male, and to the ovaria in the female. They are two small slender vessels, of considerable length, which arise from the front of the aorta, a little below the renal arteries. Each artery passes obliquely outAvards and doAvmvards, behind the peritoneum, cross- ing the ureter, and resting on the Psoas muscle, the right spermatic lying in front of the inferior vena cava, the left behind the sigmoid flexure of the colon. On reaching the margin of the pelvis, each vessel passes in front of the corresponding external iliac artery, and takes a different course in the two sexes. In the Male, it is directed outAvards, to the internal abdominal ring, and accom- panies the other constituents of the spermatic cord along the spermatic canal to the testes, Avhere it becomes tortuous, and divides into several branches, two or three of Avhich accompany the vas deferens, and supply the epididymis, anastomos- ing "with the deferential artery; others pierce the back part of the tunica albu- ginea, and supply the substance of the testis. At an early period of fcetal life, when the testes lie by the side of the spine, beloAv the kidneys, the spermatic arte- ries are short; but as these organs descend from the abdomen into the scrotum, they become gradually lengthened. In the Female, the spermatic arteries (ovarian) are shorter than in the male, 374 ARTERIES. and do not pass out of the abdominal cavity. On arriving at the margins of the pelvis, they pass inwards, between the two laminae of the broad ligament of the uterus, to be distributed to the ovaries. One or tAvo small branches supply the Fallopian tubes : another passes on to the side of the uterus, and anastomoses with the uterine arteries. Other offsets are continued along the round ligament, through the inguinal canal, to the integument of the labium and groin. The Phrenic Arteries are tAvo small vessels, -which present much variety in their origin. They may arise separately from the front of the aorta, immediately below the cceliac axis, or by a common trunk, Avhich may spring either from the aorta or from the cceliac axis. Sometimes one is derived from the aorta, and the other from one of the renal arteries. In only one out of thirty-six cases did these arte- ries arise as tAvo separate vessels from the aorta. They diverge from one another across the crura of the Diaphragm, and then pass obliquely upwards and outAvards upon its under surface. The left phrenic passes behind the oesophagus, and runs forwards on the left side of the oesophageal opening. The right phrenic, passing behind the liver and inferior vena cava, ascends along the right side of the aper- ture for transmitting that vein. Near the back part of the central tendon, each vessel divides into two branches. The internal branch runs forAvards to the ante- rior margin of the thorax, supplying the Diaphragm, and anastomosing with its fellow of the opposite side, and with the musculo-phrenic, a branch of the internal mammary. The external branch passes towards the side of the thorax, and inoscu- lates with the intercostal arteries. The internal branch of the right phrenic gives off a feAV vessels to the inferior vena cava; and the left one some branches to the oesophagus^ Each vessel also sends capsular branches to the suprarenal capsule of its OAvn side. The spleen on the left side, and the liver on the right, also receive a. feAV branches from these vessels. The Rumbar Arteries are analogous to the intercostal. They are usually four in number on each side, and arise from the back part of the aorta, nearly at right angles with that vessel. They pass outwards and backwards, around the sides of the body of the corresponding lumbar vertebra, behind the sympathetic nerve and the Psoas muscle; those on the right side being covered by the vena cava, and the two upper ones on each side by the crura of the Diaphragm. In the interval between the transverse processes of the vertebrae, each artery "divides into a dorsal and an abdominal branch. The dorsal_ branch gives off, immediately after its origin, a spinal branch, Avhich enters the spinal canal; it then continues its course backwards, between the trans- verse processes, and is distributed to the muscles and integument of the back, its ramifications anastomosing with each other, and with the posterior branches of the intercostal arteries. The spinal branch, besides supplying offsets which run along the nerves to the dura mater and cauda equina, anastomosing with the other spinal arteries, divides into two branches, one of which ascends on the posterior surface of the body of the vertebra above, and the other descends on the posterior surface of the body of the vertebra below, both vessels anastomosing with similar branches from neighboring spinal arteries. The inosculations of these vessels on each side, throughout the whole length of the spine, form a series of arterial arches behind the bodies of the vertebr-e, which are connected with each other, and with a median longitudinal vessel, extending along the centre of the bodies of the ver- tebras, by transverse branches. From these vessels offsets are distributed to the periosteum and bones. The abdominal branches pass outwards, behind the Quadratus lumborum, the lowest branch occasionally in front of that muscle, and, being continued between the abdominal^ muscles, anastomose with branches of the epigastric and internal mammary in front, the intercostals above, and those of the ilio-lumbar, and circum- flex iliac, below. The Middle Sacral Artery is a small vessel, about the size of a crow-quill, which arises from the posterior part of the aorta, just at its bifurcation. It COMMON ILIAC. 375 descends upon the last lumbar vertebra, and along the middle line of the anterior surface of the sacrum, to the upper part of the coccyx, Avhere it terminates by anastomosing Avith the lateral sacral arteries. From it branches arise Avhich run through the mesorectum^ to supply the posterior surface of the rectum. Other branches are given off on each side, Avhich anastomose Avith the lateral sacral arteries, and send off small offsets which enter the anterior sacral foramina. Common Iliac Arteries. The abdominal aorta terminates by dividing into the tAvo common iliac arteries. The bifurcation of this vessel usually takes place on the left side of the body of the fourth lumbar vertebra. This point corresponds to the left side of the umbili- cus and is on a level with a line drawn across from one crista ilii to the other. The common iliac arteries are about tAvo inches in length; diverging from the Fig. 209.—Arteries of the Pelvis. termination of the aorta, they pass downwards and outwards to the margin of t pelvis, jind divide opposite the intervertebral substance between the last hi bar vertebra and the sacrum, into two branches, the external and internal lh arteries; the former supplying the lower extremity, the latter the viscera a parietes of the pelvis. The Riqht Common Diac is somewhat longer than the left, and passes more < liquelv across the body of the last lumbar vertebra. It is covered in front by 376 ARTERIES. peritoneum, the intestines, the branches of the sympathetic nerve, and crossed, at its point of diA'ision, by the ureter. Behind, it is separated from the last lumbar ver- tebra by the tAvo common iliac veins. On its outer side it is in relation Avith the vena cava, and right common iliac vein above, and the Psoas magnus muscle below. The Left Common Iliac is in relation in front Avith the peritoneum, branches of the sympathetic nerve, the rectum, and superior hemorrhoidal artery, and crossed at its point of bifurcation, by the ureter. The left common iliac vein lies partly on the inner side, and partly beneath the artery; on its outer side, it is in relation with the Psoas magnus. Branches. The common iliac arteries give off small branches to the perito- neum, Psoae muscles, ureters, and to the surrounding cellular membrane and occasionally give origin to the ilio-lumbar, or renal arteries. Peculiarities. Its jioint of origin varies according to the bifurcation of the aorta. In three-fourths of a large number of cases, the aorta bifurcated either upon the fourth lumbar vertebra, or upon the intervertebral disc between it and the fifth; one case in nine being below, and one in eleven above this point. In ten out of every thirteen cases, the vessel bifurcated within half an inch above or below the level of the crest of the ilium • more frequently below than above. The point of division is subject to great variety. In two-thirds of a large number of cases, it was between the last lumbar vertebra and the upper border of the sacrum; in one case in eight being above, and in one in six below that point. The left common iliac artery divides lower down more frequently than the right. The relative length, also, of the two common iliac arteries varies. The right common iliac was longest in sixty-three cases; the left, in fifty-two; whilst they were both equal in fifty-three. The length of the arteries varied in five-sevenths of the cases examined, from an inch and a half to three inches; in about half of the remaining cases, the artery was longer; and in the other half, shorter; the minimum length being less than half an inch, the maximum, four and a half inches. In one instance, the right common iliac was found wanting, the external and internal iliacs arising directly from the aoita. Surgical Anatomy. The application of a ligature to the common iliac artery may be re- quired on account of aneurism or hemorrhage implicating the external or internal iliac, or on account of secondary hemorrhage after amputation of the thigh high up. It has been seen that the commencement of this vessel corresponds to the left side of the umbilicus on a level with a line drawn from the highest point of one iliac crest to the opposite one, and itscourse to a line extending from this point downwards towards fhe middle of Pou- part's ligament, The line of incision required in the first steps of an operation for securing this vessel, would materially depend upon the nature of the disease. If the surgeon select the iliac region, a curved incision, about five inches in length, may be made, commencing on the left side of the umbilicus, carried outwards towards the anterior superior iliac spine, and then along the upper border of Poupart's ligament, as far as its middle. But if the aneurismal tumor should extend high up in the abdomen, along the external iliac, it is better to select the side of the abdomen, approaching the artery from above, by making an incision from four to five inches in length, from about two inches above and to the left of the umbilicus, carried outwards in a curved direction towards the lumbar region, and terminating a little below the anterior superior iliac spine. The abdominal muscles (in either case) having been cautiously divided in succession, the transversalis fascia must be carefully cut through, and the peritoneum, together with the ureter, separated from it and from the iliac fascia, and pushed aside ; the sacro-iliac articulation must be felt for, and upon it the vessel will be felt pulsating, and may be fully exposed in close connection with its accompanying vein. On the right side, both common iliac veins, as well as the inferior vena cava, are in close connection with the artery, and must be carefully avoided. On the left side, the vein usually lies on the inner side, and behind the artery ; but it occasionally happens that the two common iliac veins are joined on the left instead of the right side, which would add much to the difficulty of an operation in such a case. If the common iliac artery is so short that danger is to be apprehended from secondary hemorrhage if a ligature is applied to it, it would be preferable, in such a ease, to tie both the external'and internal iliac near their origin. This operation has been performed in several instances; in a few with success. Internal Iliac Artery. The internal iliac artery supplies the walls and viscera of the pelvic cavity, the INTERNAL ILIAC. 377 generative organs, and inner side of the thigh. It is a short, thick vessel, smaller than the external iliac, and about an inch and a half in length, Avhich arises at the point of bifurcation of the common iliac; and, passing doAvmvards to the upper mar- gin of the great sacro-sciatic foramen, divides into tAvo large trunks, an anterior and posterior; a partially obliterated cord, the hypogastric artery, extending from the extremity of the vessel forAvards to the bladder. Relations. ^ In front, with the ureter, which separates it from the peritoneum. Behind, it is in relation Avith the internal iliac vein, the lumbo-sacral nerve, and Pyriformis muscle. By its outer side, near its origin, with the Psoas muscle. Plan of the Relations of the Internal Iliac Artery. In front. Peritoneum. Ureter. / / Internal \ Behind. Internal iliac vein. Lumbo-saeral nerve. Pyriformis muscle. In the foetus, the internal iliac artery (hypogastric) is tAvice as large as the ex- ternal iliac, and appears the continuation of the common iliac. Passing forAvards to the bladder, it ascends along the side of this viscus to its apex, to which it gives branches (superior vesical); it then passes upwards along the posterior part of the abdomen to the umbilicus, converging toAvards its fellow of the opposite side. Having passed through the umbilical opening, the two arteries twine around the umbilical vein, forming Avith it the umbilical cord; and ultimately, ramify in the substance of the placenta. That portion of the vessel placed Avithin the abdo- men, is called the hypogastric artery ; and that external to that cavity, the umbi- lical artery. At birth, AA'hen the placental circulation ceases, that portion of the hypogastric artery Avhich extends from the umbilicus to the apex of the bladder, contracts, and ultimately dwindles to a solid fibrous cord; the portion of the same vessel extend- ing from the apex of the bladder to Avithin an inch and a half of its origin, is not totally impervious, though it becomes considerably reduced in size; and serves to convey blood to the bladder, under the name of the superior vesical artery. Peculiar ides, as regards its length. In two-thirds of a large number of cases, the length of the internal iliac varied between an inch and an inch and a half; in the remaining third, it was more frequently longer than shorter, the maximum length being three inches, the minimum, half an inch. The lengths of the common and internal iliac arteries bear an inverse proportion to each other, the internal iliac artery being long when the common iliac is short, and vice versa. As regards its place of division. The place of division of the internal iliac varies between the upper margin of the sacrum, and the upper border of the sacro-sciatic foramen. The arteries of the two sides in a series of cases often differed in length, but neither seemed constantly to exceed the other. Surgical Anatomy. The application of a ligature to the internal iliac artery may be re- quired in cases of aneurism or hemorrhage affecting one of its branches. This vessel may be secured by making an incision through the abdominal parietes in the iliac region, in a direction and to an extent similar to that for securing the common iliac; the transversalis fascia having been cautiously divided, and the peritoneum pushed inwards from the iliac fossa towards the pelvis, the finger may feel the pulsation of the external iliac at the bottom of the wound ; and, by tracing this vessel upwards, the internal iliac is arrived at, opposite the Outer side. Psoas magnus. 378 ARTERIES. sacro-iliac articulation. It should be remembered that the vein lies behind, and on the ii<>ht side a little external to the artery, and in close contact with it; the ureter and peritoneum which lie in front, must also be avoided. The degree of facility in applying a ligature to this vessel, will mainly depend upon its length. It has been seen, that in the great majority of the cases examined, the artery was short, varying from an inch to an inch and a half; in these cases, the artery is deeply seated in the pelvis; when, on the contrary, the vessel is longer it is found partly above that cavity. If the artery is very short, which occasionally happens, it would be preferable to apply a ligature to the common iliac, or upon the external and internal iliacs at their origin. Branches of the Internal Iliac From the Anterior Trunk. From the Posterior Trunk. Superior Aesical. Gluteal. Inferior vesical. Ilio-lumbar. Middle hemorrhoidal. Lateral sacral. Obturator. Internal pudic. Sciatic. t t? 7 f Uterine. fn female. { T7- . , ( Vaginal. The Superior Vesical is that part of the foetal hypogastric artery which remains pervious after birth. It extends to the side of the bladder, distributing numerous branches to the body and fundus of this organ. From one of these a slender vessel is derived, which accompanies the vas deferens in its course to the testis, where it anastomoses with the spermatic artery. This is the artery of the vas deferens. Other branches supply the ureter. The Middle Vesical, usually a branch of the superior, is distributed to the base of the bladder, and under-surface of the vesiculre seminales. The Inferior Vesical arises from the anterior division of the internal iliac, in common with the middle hemorrhoidal, and is distributed to the base of the bladder, the prostate gland, and vesicuhe seminales. Those branches distributed to the prostate communicate with the corresponding vessel of the opposite side. The Middle Hemorrhoidal Artery usually arises together with the preceding ves- • Lt *uPPhes the rectum, anastomosing with the other hemorrhoidal arteries. Ihe Lferine Artery passes downwards from the anterior trunk of the internal iliac to the neck of the uterus. Ascending, in a tortuous course, on the side of this viscus, between the layers of the broad ligament, it distributes branches to its substance anastomosing, near its termination, with a branch from the ovarian artml7' T^ranches from this vessel are also distributed to the bladder and ureter. Hie J aginal Artery is analogous to the inferior vesical in the male; it descends U?°.? £ v?Sma> supplying its mucous membrane, and sending branches to the neck ot the bladder, and contiguous part of the rectum. The Obturator Artery usually arises from the anterior trunk of the internal iliac, frequently from the posterior. It passes forwards below the brim of the pelvis to the groove in the upper border of the obturator foramen, and escaping rom the pelvic cavity through this aperture, divides into an internal and an ex- ternal branch. In the pelvic cavity, this vessel lies upon the pelvic fascia, beneath the peritoneum, and a little below the obturator nerve; and whilst passing through the obturator foramen, is contained in an oblique canal, formed by the horizontal branch ot the pubes, above, and the arched border of the obturator membrane, beloAv. Branches. Within the pelvis, the obturator artery gives off an iliac branch to the iliac fossa, which supplies the bone and the Iliacus muscle, and anastomoses Yki ~fi "J arteiT; a Ve*lWd hraneh' which runs backwards to supply he bladder; anda^Aw branch, whiel. is given off from the vessel just before it leaves the pelvic cavity. It ascends upon the back of the pubes, commu- ORTURATOR; INTERNAL PUDIC. 379 nicating with offsets from the epigastric artery, and with the corresponding vessel of the opposite side. This branch is placed on the inner side of the femoral ring. External to the pelvis, the obturator artery divides into an external and an inter- nal branch, Avhich are deeply situated beneath the External obturator muscle, skirting the circumference of the obturator foramen, and anastomosing at the lower part of this aperture Avith each other, and Avith branches of the internal circumflex artery. The interned branch curves inAvards along the inner margin of the obturator foramen, distributing branches to the Obturator muscles, Pectineus, Adductors, and Gracilis, and anastomoses Avith the external branch, and with the internal cir- cumflex artery. The external branch curves around the outer margin of the foramen, to the space betAveen the Gemellus inferior and Quadratus femoris, Avhere it anastomoses with the sciatic artery. It supplies the Obturator muscles, anastomoses, as it passes backAvards, with the internal circumflex, and sends a branch to the hip joint through the cotyloid notch, Avhich ramifies on the round ligament as far as the head of the femur. Peculiarities. In two out of * every three cases this vessel arises from the internal iliac ; in one case in '6] from the epigastric; and in about one in seventy-two cases by two roots from both vessels. It arises in about the same proportion from the external iliac artery. The origin of the obturator from the epigastric is not commonly found on both sides of the same body. When the obturator artery arises at the front of the pelvis from the epigastric, it descends almost vertically downwards to the upper part of the obturator foramen. The artery in this course usually descends in contact with the external iliac vein, and lies on the outer side of the femoral ring; in such cases it would not be endangered in the operation for femoral hernia. Occasionally, however, it curves inwards along the free margin of Gimbernat's ligament, and under such circumstances it would almost completely encircle the neck of a hernial sac (sup- posing a hernia to exist in such a case), and would be in great danger of being wounded if an operation was necessary. The Internal Pudic is the smaller of the two terminal branches of the anterior trunk of the internal iliac, and supplies the external organs of generation. It passes downAvards and outAvards to the loAver border of the great sacro-sciatic foramen, and emerges from the pelvis betAveen the Pyriformis and Coccygeus muscles ; it then crosses the spine of the ischium, and enters that cavity through the lesser sacro-sciatic foramen. The artery now crosses the Internal obturator muscle, to the ramus of the ischium, being covered by the obturator fascia, and situated about an inch and a half from the margin of the tuberosity : it then ascends for- wards and upAvards along the ramus of the ischium, pierces the posterior layer of the deep perineal fascia, and runs forAvards along the inner margin of the ramus of the pubes : finally it perforates the anterior layer of the deep perineal fascia, and divides into its two terminal branches, the dorsal artery of the penis, and the artery of the corpus cavernosum. Relations. In the first part of its course, within the pelvis, it lies in front of the Pyriformis muscle and sacral plexus of nerves, and on the outer side of the rec- tum (on the left side). As it crosses the spine of the ischium, it is covered by the Gluteus maximus, and great sacro-sciatic ligament. And Avhen it enters the pelvis, it lies on the outer side of the ischio-rectal fossa, upon the surface of the Obturator internus muscle, contained in a fibrous canal formed by the obturator fascia and the falciform process of the great sacro-sciatic ligament. It is accom- panied by the pudic veins, and the internal pudic nerve. Peculiarities. The internal pudic is sometimes smaller than usual, or fails to give off one or two of its usual branches ; in such cases, the deficiency is supplied by branches^ derived from an additional vessel, the accessory pudic, which generally arises from the pudic artery before its exit f.iom the great sacro-sciatic foramen, and passes forwards near the base of the bladder, on the upper part of the prostate gland to the perinaeum, where it gives off those branches usually derived from the pudic artery itself. The deficiency most frequently met 380 ARTERIES. with, is that in which the internal pudic ends as the artery of the bulb; the artery of the corpus cavernosum and arteria dorsalis penis being derived from the accessory pudic. Or the pudic may terminate as the superficial perineal, the artery of the bulb being derived, with the other two branches, from the accessory vessel. The relation of the accessory pudic to the prostate gland and urethra, is of the greatest interest in a surgical point of view, as this vessel is in danger of being wounded in the lateral operation of lithotomy. Branches. Within the pelvis, the internal pudic gives off several small branches Avhich supply the muscles, sacral nerves, and viscera in this cavity. In the peri- naum the folloAving branches are given off. Inferior or external hemorrhoidal. Artery of the bulb. Superficial perineal. Artery of the corpus cavernosum. Transverse perineal. Dorsal artery of the penis. The External Hemorrhoidal are tAvo or three small arteries, which arise from the internal pudic as it passes above the tuberosity of the ischium. Crossing the ischio-rectal fossa, they are distributed to the muscles and integument of the anal region. The Superficial Perineal Artery supplies the scrotum, and muscles, and integu- ment of the perinaeum. It arises from the internal pudic, in front of the preceding branches, and piercing the loAver border of the deep perineal fascia, runs across the transversus perinaei, and through the triangular space betAveen the Accelerator urinae and Erector penis, both of Avhich it supplies, and is finally distributed to the skin of the scrotum and dartos. In its passage through the perinasum it lies beneath the superficial perineal fascia. The Transverse Perineal is a small branch, Avhich arises either from'the internal pudic, or from the superficial perineal artery as it crosses the Transversus perinasi muscle. Piercing the lower border of the deep perineal fascia, it runs transversely inwards along the cutaneous surface of the Transversus perinaei muscle, which it supplies, as well as the structures between the anus and bulb of the urethra. The Artery of the Bulb is a large but very short vessel, arising from the internal pudic betAveen the two layers of the deep perineal fascia and passing nearly trans- versely inAvards, pierces the bulb of the urethra, in which it ramifies. It gives off a small branch which descends to supply CoAvper's gland. This artery is of consi- derable importance in a surgical point of vieAv, as it is in danger of being Avounded m the lateral operation of lithotomy, an accident usually attended with severe and alarming hemorrhage. This vessel is sometimes very small, occasionally wanting, or even double. It sometimes arises from the internal pudic earlier than usual, and crosses the perinaeum to reach the back part of the bulb. In such a case the vessel could hardly fail to be Avounded in the performance of the lateral operation of lithotomy. If, on the contrary, it should arise from an accessory pudic, it lies more forward than usual, and is out of danger in the operation. The Artery of the Corpus Cavernosum^one of the terminal branches of the internal pudic, arises from that vessel while it is situated betAveen the crus penis and the ramus of the pubes ; piercing the crus penis obliquely, it runs forwards m the corpus cavernosum by the side of the septum pectiniforme, to which its branches are distributed. The Dorsal Artery of the Penis ascends between the crus and pubic symphysis, and piercing the suspensory ligament, runs forwards on the dorsum of the penis to the glans, where it divides into tAvo branches, which supply the glans and prepuce. On the dorsum of the penis, it lies immediately beneath the integument, parallel with the dorsal vein and corresponding artery of the opposite side. It supplies the integument and fibrous sheath of the corpus cavernosum. The Internal Pudic Artery in the Female is smaller than in the male. Its origin and course are similar, and there is considerable analogy in the distribution of its branches. The superficial artery supplies the labia pudenda ; the artery of the bulb supplies the erectile tissue of the bulb of the vagina, whilst the two ter- SCIATIC. 381 Fig. ilO.—The Arteries of the Gluteal and Posterior Femora] Region?. minal branches supply the clitoris ; the artery of the corpus cavernosum, the cavernous body of the clitoris ; and the arteria dorsalis clitoridis, the dorsum of that organ. The Sciatic Artery (Fig. 210), the larger of the twro terminal branches of the anterior trunk of the in- ternal iliac, is distributed to the muscles on the back of the pelvis. It passes downwards to the lower part of the great sacro- sciatic foramen, behind the internal pudic, resting on the sacral plexus of nerves and Pyriformis muscle, and escapes from the pehls be- tween the Pyriformis and Coccygeus. It then de- scends in the interval betAveen the Trochanter major and tuberosity of the ischium, accompanied by the sciatic nerves, and covered in by the Glutaeus maximus, and divides into branches, which supply the deep muscles at the back of the hip. Within the pelvis, it dis- tributes branches to the Pyriformis, Coccygeus, and Levator ani muscles ; some hemorrhoidal branches, which supply the rectum, and occasionally take the place of the middle hemor- rhoidal artery ; and vesical branches to the base and neck of the bladder, vesi- cular seminales, and pros- tate gland. Externed to the pelvis, it gives off the coccy- geal, inferior gluteal, comes nervi ischiadici, muscular, and articular branches. The Coccygeal Branch runs inwards, pierces the great sacro-sciatic liga- ment, and supplies the Glutaeus maximus, the integument, and other structures on the posterior surface of the coccyx. The Inferior Gluteal Branches, three or four in number, supply the Glutseus maximus muscle. The Comes Nervi Ischiadici is a long slender vessel, which accompanies the great sciatic nerve for a short distance ; it then penetrates it, and runs in its sub- stance to the loAver part of the thigh. SuprrUnt 382 ARTERIES. The Muscular Branches supply the muscles on the back part of the hip, anas- tomosing Avith the gluteal, internal and external circumflex, and superior perfo- rating arteries. Some articular branches are also distributed to the capsule of the hip joint. The Gluteal Artery is the largest branch of the internal iliac, and appears to be the continuation of the posterior division of that vessel. It is a short thick trunk, Avhich passes downAvards to the upper part of the great sacro-sciatic foramen, escapes from the pelvis above the upper border of the Pyriformis muscle, and immediately divides into a superficial and deep branch. Within the pelvis, it gives off a few muscular branches to the Iliacus, Pyriformis, and Obturator internus, and, just previous to quitting that cavity, a nutritious artery, which enters the ilium. The superficial branch passes beneath the Glutaeus maximus, and divides into numerous branches, some of Avhich supply this muscle, Avhilst others perforate its tendinous origin, and supply the integument of the posterior surface and side of the sacrum, anastomosing with the posterior branches of the sacral arteries. The deep branch runs between the Glutaeus medius and minimus, and subdi- vides into two. Of these, the superior division, containing the original course of the vessel, passes along the upper border of the Glutasus minimus to the anterior superior spine of the ilium, anastomosing with the circumflex iliac and ascending branches of the external circumflex artery. The inferior division crosses the Glutaeus minimus obliquely to the trochanter major, distributing branches to the Glutaei muscles, and inosculates Avith the external circumflex artery. Some branches pierce the Glutaeus minimus to supply the hip joint. The Ilio-lumbar Artery ascends beneath the Psoas muscle and external iliac vessels, to the upper part of the iliac fossa, where it divides into a lumbar and an iliac branch. The lumbar branch supplies the Psoas and Quadratus lumborum muscles, anas- tomosing Avith the left lumbar artery, and sends a small spinal branch through the intervertebral foramen, betAveen the last lumbar vertebra and the sacrum, into the spinal canal, to supply the spinal cord and its membranes. The iliac branch descends to supply the Iliacus internus, some offsets running betAveen the muscle and the bone, one of which enters an oblique canal to supply the diploe, whilst others run along the crest of the ilium, distributing branches to the Gluteal and Abdominal muscles, and anastomosing in their course "with the gluteal, circumflex ilii, external circumflex, and epigastric arteries. The Lateral Sacred Arteries are usually tAvo in number on each side, superior and inferior. The superior, Avhich is of large size, passes inwards, and after anastomosing with branches from the middle sacral, enters the first or second sacral foramen, is dis- tributed to the contents of the sacral canal, and escaping by the corresponding posterior sacral foramen, supplies the skin and muscles on the dorsum of the sacrum. The inferior branch passes obliquely across the front of the Pyriformis muscle and sacral nerves to the inner side of the anterior sacral foramina, descends on the front of the sacrum, and anastomoses over the coccyx with the sacra media and opposite lateral sacral arteries. In its course, it gives off branches, which enter the anterior sacral foramina; these after supplying the bones and membranes of the interior of the spinal canal, escape by the posterior sacral foramina, and are distributed to the muscles and skin on the dorsal surface of the sacrum. External Iliac Artery. The external iliac artery is the chief vessel which supplies the lower limb. It is larger in the adult than the internal iliac, and passes obliquely downwards and outwards along the inner border of the Psoas muscle, from the bifurcation of the common iliac to the femoral arch, where it enters the thigh, and becomes the femoral artery. The course of this vessel would be indicated by a line drawn from the left side of the umbilicus to a point midway betAveen the anterior superior spinous process of the ilium and the symphysis pubis. EXTERNAL ILIAC 383 Relations. In front, with the peritoneum, subperitoneal areolar tissue, the intes- tines, and a thin layer of fascia, derived from the iliac fascia, which surrounds the artery and vein. At its origin it is occasionally crossed by the ureter. The spermatic vessels descend for some distance upon it near its termination, and it is crossed in this situation by a branch of the genito-crural nerve and the circumflexa ilii vein; the vas deferens curves doAvn along its inner side. Behind, it is in rela- tion Avith the external iliac vein, which, at the femoral arch, lies at its inner side; on the left side the vein is altogether internal to the artery. Externally, it rests against the Psoas muscle, from Avhich it is separated by the iliac fascia. The artery rests upon this muscle near Poupart's ligament. Numerous lymphatic ves- sels and glands are found lying on the front and inner side of the vessel. Plan of the Relations of the External Iliac Artery. In front. Peritoneum, intestines, and iliac fascia. xt f Spermatic vessels. -,-, ' , ) Genito-crural Nerve. Poupart s < n- a .,.. T • I bircumnexa ilii vein. Ligament. | T , .. , , , , e t. Lymphatic vessels and -glands. Outer side. -, Inner side. Psoas magnus. External iliac vein and vas deferens Iliac fascia. j External at femorai arch I Iliac. Behind. External iliac vein. Surgical Anatomy. The application of a ligature to the external iliac maybe required in cases of aneurism of the femoral artery, or in cases of secondary hemorrhage, after the latter vessel has been tied for popliteal aneurism. This vessel may be secured in any part of its course, excepting near its upper end, on account of the circulation through the internal iliac, and near its lower end, on account of the origin of the epigastric and circumflex vessels. One of the chief points in the performance of the operation is to secure the vessel without injury to the peritoneum. The patient having been placed in the recumbent posi- tion, an incision should be made, commencing about an inch above and to the inner side of the anterior superior spinous process of the ilium, and running downwards and outwards to the outer end of Poupart's ligament, and parallel with its outer half, to a little above its middle. The abdominal muscles and transversalis fascia having been cautiously divided, the peritoneum should be separated from the iliac fossa and pushed towards the pelvis; and on introducing the finger to the bottom of the wound the artery may be felt pulsating along the inner border of the Psoas muscle. The external iliac vein is situated along the inner side of the artery, and must be cautiously separated from it by the finger-nail, or point of the knife, and the aneurism-needle should be introduced on the inner side, between the artery and vein. Branches. Resides several small branches to the Psoas muscle and the neighbor- nig lymphatic glands, the external gives off tAvo branches of considerable size, the Epigastric. Circumflexa ilii. The Epigastric Artery arises from the external iliac, a feAV lines above Poupart's ligament. It at first descends to reach this ligament, and then ascends obliquely upAvards and inAvards betAveen the peritoneum and transversalis fascia, to the margin of the sheath of the Rectus muscle. Having perforated the sheath near its loAver third, it ascends vertically upAvards behind the Rectus, to which it is distributed, dividing into numerous branches, Avhich anastomose above the umbi- licus with the terminal branches of the internal mammary and inferior intercostal arteries. It is accompanied by two veins, which usually unite into a single trunk before their termination in the external iliac vein. As this artery ascends from Poupart's ligament to the Rectus, it lies behind the inguinal canal, to the inner side of the internal abdominal ring, and immediately above the femoral ring, the vas deferens in the male, and the round ligament in the female, crossing behind the artery in descending into the pelvis. 381 ARTERIES. Branches. The branches of this vessel are the cremasteric, Avhich accompanies the spermatic cord, and supplies the Cremaster muscle, anastomosing with the spermatic artery; a pubic branch, Avhich runs across Poupart's ligament, and then descends behind the pubes to the inner side of the crural ring, and anastomoses Avith offsets from the obturator artery; muscular branches, some of AAThich are dis- tributed to the abdominal muscles and peritoneum, anastomosing with the lumbar and circumflexa ilii arteries; others perforate the tendon of the External oblique and supply the integument, anastomosing with branches of the external epigastric. Peculiarities. The origin of the epigastric may take place from any part of the external iliac between Poupart's ligament and two inches and a half above it; or it may arise below this ligament, from the femoral, or from the deep femoral. Union with Branches. It frequently arises from the external iliac by a common trunk with the obturator. Sometimes the epigastric arises from the obturator, the latter vessel being furnished by the internal iliac, or the epigastric may be formed of two branches, one derived from the external iliac, the other from the internal iliac. The Circumflex Iliac Artery arises from the outer side of the external iliac, nearly opposite the epigastric artery. It ascends obliquely outAvards behind Pou- part's ligament, and runs along the inner surface of the crest of the ilium to about its middle, where it pierces the Transversalis, and runs backwards between this muscle and the Internal oblique, to anastomose with the ilio-lumbar and gluteal arteries. Opposite the anterior superior spine of the ilium, it givTes off a large branch, Avhich ascends betAveen the Internal oblique and Transversalis muscles, supplying them and anastomosing with the lumbar and epigastric arteries. The circumflex iliac artery is accompanied by two veins, Avhich are united into a single trunk; this crosses the external iliac artery just above Poupart's ligament, and enters the external iliac vein. Femoral Artery. The femoral artery is the continuation of the external iliac. It commences immediately beneath Poupart's ligament, midway betAveen the anterior superior spine of the ilium aud the symphysis pubis, and passing doAvn the forepart and inner side of the thigh, terminates at the opening in the Adductor magnus, at the junction of the middle Avith the loAver third of the thigh, where it becomes the popliteal artery. A line drawn from a point midway between the anterior superior spine of the ilium and the symphysis of the pubes to the inner side of the internal condyle of the femur, will be nearly parallel with the course of this artery. This vessel, at the upper part of the thigh, lies a little internal to the head of the femur; in the lower part of its course, on the inner side of the shaft of this bone, and between these two points the vessel is separated from the bone by a considerable interval. In the upper third of the thigh the femoral artery is very superficial, being covered by the integument, inguinal glands, and by the superficial and deep fasciae, and is contained in a triangular space, called " Scarpa's triangle." ^ Scarpa's Triangle. Scarpa's triangle corresponds to the depression seen imme- diately below the fold of the groin. It is a triangular space, the apex of Avhich is directed downwards, and the sides of which are formed externally by the Sartorius, internally by the Adductor longus, and the base by Poupart's ligament. The floor of this space is formed from without inwards by the Iliacus, Psoas, Pectineus, Adductor longus, and a small part of the adductor brevis muscles; and it is divided into two nearly equal parts by the femoral artery and vein, which extend from the middle of its base to its apex: the artery giving off in this situation its cutaneous and profunda branches, the vein receiving the deep femoral and internal saphena veins. In this space, the femoral artery rests on the inner margin of the Psoas muscle, which separates it from the capsular ligament of the hip joint. The artery in this situation is crossed in front by the crural branch of the genito- crural nerve, and behind by the branch to the Pectineus from the anterior crural. FEMORAL. 385 211.—Surgical Anatomy of the Femoral Artery. The femoral vein lies at its inner side, betAveen the margins of the Pectineus and Psoas muscles. The anterior crural nerve lies about half an inch to the outer side of the femoral artery, deeply imbedded between the Iliacus and Psoas muscles ; and on the Iliacus muscle, internal to the anterior superior spi- nous process of the ilium, is the external cutaneous nerA'e. The femoral artery and vein are inclosed in a strong fibrous sheath, form- ed by fibrous and cellular tissue, and by a process of fascia sent inwards from the fascia lata ; the vessels are separated, hoAvever, from one another by thin fibrous partitions. In the middle third of the thigh, the femoral ar- tery is more deeply seated, being covered by the in- tegument, the superficial and deep fasciae, and the Sartorius, and is contained in an aponeurotic canal, formed by a dense fibrous band Avhich extends trans- versely from the Vastus internus to the tendons of the Adductor longus and magnus muscles. In this part of its course it lies in a depression, bounded externally by the Vastus internus, internally by the Adductor longus and Ad- ductor magnus. The fe- moral vein lies on the outer side of the artery, in close apposition with it, and, still more externally, is the internal (long) saphenous nerve. Relations. From above downwards, the femoral artery rests upon the Psoas muscle, which separates it from the margin of the pelvis and capsular ligament hip ; it is next separated from the Pectineus, by the profunda vessels and it then lies upon the Adductor longus ; and lastly, upon the tendon To its inner side Super. E~.trrn Infer. Anter. Tibij. q'l/uruiusAW May 7i& of the femoral vein of the Adductor magnus, the femoral vein being interposed. it is in relation, above, with the femoral vein, and, lower down, with the Adductor longus, and Sartorius. To its outer side, the Vastus internus separates it from the femur, in the loAver part of its course. 27 380 ARTERIES. The femoral vein, at Poupart's ligament, lies close to the inner side of the artery separated from it by a thin fibrous partition, but, as it descends, gets behind it' and then to its outer side. The internal saphenous nerve is situated on the outer side of the artery, in the middle third of the thigh, beneath the aponeurotic covering, but not within the sheath of the vessels. Small cutaneous nerves cross the front of the sheath. Peculiarities. Double femoral reunited. Four cases are at present recorded, in which the femoral artery divided into two trunks below the origin of the Profunda, and became reunited near the opening in the Adductor magnus, so as to form a single popliteal artery. One of them occurred in a patient operated upon for popliteal aneurism. Change e>f Position. A similar number of cases have been recorded, in which the femoral artery was situated at the back of the thigh, the vessel being continuous above with the in- ternal iliac, escaping from the pelvis through the great sacro-sciatic foramen, and accompany- ing the great sciatic nerve to the popliteal space, where its division occurred in the usual manner. Position of the vein. The femoral A^ein is occasionally placed along the inner side of the artery, throughout the entire extent of Scarpa's triangle; or it may be slit, so that a lar"e vein is placed on each side of the artery for a greater or less extent. Origin of the profunda. This vessel occasionally arises from the inner side, and more rarely, from the back of the common trunk; but the more important peculiarity, in a sur- gical point of view, is that which relates to the height at which the vessel arises from the femoral. In three-fourths of a large number of cases, it arose between one and two inches below^ Poupart's ligament; in a few cases, the distance was less than an inch; more rarely, opposite the ligament; and in one case, above Poupart's ligament, from the external iliac. Occasionally, the distance between the origin of the vessel and Poupart's ligament exceeds two inches, and in one case it was found to be as much as four inches. Surgical Anatomy. Compression of the femoral artery, which is constantly requisite in amputations, or other operations on the lower limb, is most effectually made immediately below Poupart's ligament. In this situation, the artery is very superficial, and is merely separated from the margin of the acetabulum and front of the head of the femur, by the Psoas muscle; so that the surgeon, by means of his thumb, or any other resisting body, may effectually con- trol the circulation through it. This vessel may also be compressed in the middle third of the thigh, by placing a compress over the artery, beneath the tourniquet, and directing the pressure from within outwards, so as to compress the vessel on the inner side of the shaft of the femur. The application of a ligature to the femoral artery may be required in cases of wound or . aneurism of the arteries of the leg, of the popliteal or femoral; and the vessel may be exposed and tied in any part of its course. The great depth of this vessel in the middle of the thigh, its close connection with important structures, and the density of its sheath, render the ope- ration in this situation one of much greater difficulty than the application of a ligature in the upper part of its course, where it is more superficial. Ligature of the femoral artery, within two inches of its origin, is usually considered very unsafe, on account of the connection of large branches with it, the epigastric and circumflex iliac arising just above its origin ; the profunda, from one to two inches below; occasionally, also, one of the circumflex arteries arises from the vessel in the interspace between these. ihe profunda sometimes arises higher than the point above mentioned, and rarely between two or three inches (in one case four) below Poupart's ligament. It would appear, then, that the most favorable situation for the application of a ligature to this vessel, is between tour or five inches from its point of origin. In order to expose the artery in this situation, an incision between two and three inches long, should be made in the course of the vessel, the patient lying in the recumbent position, with the limb slightly flexed and abducted. A large vein is frequently met with, passing in the course of the artery to join the saphena; this must be avoided, and the fascia lata having been cautiously divided, and the Sartorius exposed, this muscle must be drawn outwards, in order to fully expose the sheath of the vessels. Ihe finger being introduced into the wound, and the pulsation of the artery felt, the sheath should be divided over it to a sufficient extent to allow of the introduction of the ligature, but no further; otherwise, the nutrition of the coats of the vessel may be interfered with or muscular branches which arise from the vessel at irregular intervals may be divided. In this part of the operation, a small nerve which crosses the sheath should be avoided. The aneurism-needle must be carefully introduced and kept close to the artery, to avoid the femoral vein, which lies behind the vessel in this part of its course. RRANCHES OF FEMORAL. 387 To expose the artery in the middle of the thigh, an incision should be made through the integument, between three and four inches in length, over the inner margin of the Sartorius, taking care to avoid the internal saphena vein, the situation of which may be previously known by compressing it higher up in the thigh. The fascia lata having been divided, and the Sartorius muscle exposed, it should be drawn outwards, when the strong fascia which is stretched across from the Adductors to the Vastus internus, will be ex- posed, and must be freely divided; the sheath of the vessels is now seen, and must be opened, and the artery secured by passing the aneurism-needle between the vein and artery, in the direction from within outwards. The femoral vein in this situation lies on the outer side of the artery, the long saphenous nerve on its anterior and outer side. It has been seen that the femoral artery occasionally divides into two trunks, below the origin of the profunda. If, in the operation for tying the femoral, two vessels are met with, the surgeon should alternately compress each, in order to ascertain which vessel is connected with the aneurismal tumor, or with the bleeding from the wound, and that one only tied which controls it. If, however, it is necessary to compress both vessels before the circulation in the tumor is controlled, both should be tied, as it would be probable that they became reunited, as is mentioned above. Branches. The branches of the femoral artery are the Superficial epigastric. Superficial circumflex iliac. Superficial external pudic. Deep external pudic. ( External circumflex. Profunda. < Internal circumflex. ( Three perforating. Muscular. Anastomotica magna. The Superficial Epigastric arises from the femoral, about half an inch beloAV Poupart's ligament, and, passing through the saphenous opening in the fascia lata, ascends on to the abdomen, in the superficial fascia covering the External oblique muscle, nearly as high as the umbilicus. It distributes branches to the inguinal glands, the superficial fascia and integument, anastomosing Avith branches of the deep epigastric, and internal mammary arteries. The Superficial Circumflex Iliac, the smallest of the cutaneous branches, arises close to the preceding, and, piercing the fascia lata, runs outAvards, parallel with Poupart's ligament, as far as the crest of the ilium, dividing into branches which supply the integument of the groin, the superficial fascia, and inguinal glands, anastomosing Avith the deep circumflex iliac, and with the gluteal and external circumflex arteries. The Superficial External Pudic (superior) arises from the inner side of the femoral artery, close to the preceding vessels, and, after piercing the fascia lata at the saphenous opening, passes inAvards, across the spermatic cord, to be dis- tributed to the integument of the loAver part of the abdomen, and of the penis and scrotum in the male, and to the labia in the female, anastomosing Avith branches of the internal pudic. The Deep External Pudic (inferior), more deeply seated than the preceding, passes inAvards on the Pectineus muscle, covered by the fascia lata, Avhich it pierces opposite the ramus of the pubes, its branches being distributed in the male, to the integument of the scrotum and perinaeum, and in the female to the labium, anastomosing with branches of the superficial perineal artery. The Profunda Femoris (deep femoral artery) nearly equals the size of the superficial femoral. It arises from the outer and back part of the femoral artery, from one to two inches below Poupart's ligament. It at first lies on the outer side of the superficial femoral, and then passes beneath it and the femoral vein to the inner side of the femur, and terminates at the lower third of the thigh in a small branch, Avhich pierces the Adductor magnus, to be distributed to the Flexor muscles, on the posterior part of the thigh, anastomosing with branches of the popliteal and inferior perforating arteries. 388 ARTERIES. Relations. Behind, it lies first upon the Iliacus, and then on the Adductor bre- vis and Adductor magnus muscle. In front, it is separated from the femoral arterv; above, by the femoral and profunda veins ; and below, by the Adductor longus. On its outer side, the insertion of the Vastus internus separates it from the femur. Plan of the Relations of the Profunda Artery. In front. Femoral and profunda vreins. Adductor longus. / I Profunda. ' Behind. Iliacus. Adductor brevis. Adductor magnus. The External Circumflex Artery supplies the muscles on the front of the thigh. It arises from the outer side of the profunda, passes horizontally outAvards, betAveen the divisions of the anterior crural nerve, and beneath the Sartorius and Rectus muscles, and divides into three sets of branches, ascending, transverse, and descending. The ascending branches pass upwards, beneath the Tensor vaginae femoris muscle, to the outer side of the hip, anastomosing Avith the terminal branches of the gluteal and circumflex iliac arteries. The descending branches, three or four in number, pass downAvards, beneath the Rectus, upon the Vasti muscles, to which they are distributed, one or tAvo passing beneath the Vastus externus as far as the knee, anastomosing Avith the superior articular branches of the popliteal artery. The transverse branches, the smallest and least numerous, pass outwards over the Cruneus, pierce the Vastus externus, and Avind around the femur to its back part, just below the great trochanter, anastomosing at the back of the thigh Avith the internal circumflex, sciatic, and superior perforating arteries. The Internal Circumflex Artery, smaller than the external, arises from the inner and back part of the profunda, and Avinds around the inner side of the femur, betAveen the Pectineus and Psoas muscles. On reaching the tendon of the Obturator externus, it divides into tAvo branches ; one, ascending, is distributed to the Adductor muscles, the Gracilis, and Obturator externus, anastomosing with the obturator artery, a descending branch which passes beneath the Adductor brevis, to supply it and the great Adductor ; the continuation of the vessel passing backAvards, betAveen the Quadratus femoris and upper border of the Adductor magnus, anastomosing with the sciatic, external circumflex, and superior perfora- ting arteries. Opposite the hip joint, this branch gives off an articular vessel, Avhich enters the joint beneath the transverse ligament; and, after supplying the adipose tissue, passes along the round ligament to the head of the bone. The Perforating arteries (Fig. 210), usually three in number, are so called from their perforating the tendons of the Adductor brevis and magnus muscles to reach the back of the thigh. The First or Superior Perforating Artery passes backAvards betAveen the Pec- tineus and Adductor brevis (sometimes perforates the latter); it then pierces the Adductor magnus close to the linea aspera, and divides into branches which supply both Adductors, the Riceps, and Glutaeus maximus muscle; anastomosing with the sciatic, internal circumflex, and middle perforating arteries. The Second or Middle Perforating Artery, larger than the first, passes through the tendons of the Adductor brevis and Adductor magnus muscles; divides Outer side. Vastus Internus. POPLITEAL. 389 into ascending and descending branches, Avhich supply the flexor muscles of the thigh; anastomosing with the superior and inferior perforantes. The nutrient artery of the femur is usually given off from this branch. The Third or Inferior Perforating Artery is given off below the Adductor brevis ; it pierces the Adductor magnus, and divides into branches Avhich supply the flexor muscles of the thigh ; anastomosing Avith the perforating arteries, above, and with the terminal branches of the profunda, beloAv. Muscular Brandies are given off from this vessel throughout its entire course. They vary from two to seven in number, and supply chiefly the Sartorius and Vastus internus. The Anastomotica Magna arises from the femoral artery just before it passes through the tendinous opening in the Adductor magnus muscle, and divides into a superficial and deep branch. The superficial branch accompanies the long saphenous nerve, beneath the Sartorius, and piercing the fascia lata, is distributed to the integument. The deep branch descends in the substance of the Vastus internus, lying in front of the tendon of the Adductor magnus, to the inner side of the knee, Avhere it anastomoses Avith the superior internal articular artery and recurrent branch of the anterior tibial. A branch from this vessel crosses, outAvards above the articular surface of the femur, forming an anastomotic arch with the superior external arti- cular artery, and supplies branches to the knee joint. Popliteal Artery. The popliteal artery commences at the termination of the femoral, at the opening in the Adductor magnus, and passing obliquely doAvmvards and outAvards behind the knee joint, to the lower border of the Popliteus muscle, divides into the anterior and posterior tibial arteries. Through this extent the artery lies in the popliteal space. The Popliteal Space. Dissect ion. A vertical incision about eight inches in length should be made along the back part of the knee joint, connected above and below by a transverse incision passing from the inner to the outer side of the limb. The flaps of integument included between these inci- sions should be reflected in the direction shown in Fig. 171. On removing the integument, the superficial fascia is exposed, and ramifying in it along the middle line are found some filaments of the small sciatic nerve, and towards the inner part, some offsets from the internal cutaneous nerve. The superficial fascia having been removed, the fascia lata is brought into aIcav. In this region it is strong and dense, being strengthened by transverse fibres, and firmly attached to the tendons on the inner and outer sides of the space. It is perforated beloAV by the external saphena vein. This fascia having been reflected back in the same direction as the integument, the small sciatic nerve and ex- ternal saphena vein are seen immediately beneath it, in the middle line. If the loose adipose tissue is now removed, the boundaries and contents of the space may be examined. Boundaries. The popliteal space, or the ham, occupies the lower third of the thigh and the upper fifth of the leg ; extending from the aperture in the Adductor magnus, to the loAver border of the Popliteus muscle. It is a lozenge-shaped space, being widest at the back part of the knee joint, and deepest above the arti- cular end of the femur. It is bounded, externally, above the joint, by the Biceps, and below the articulation, by the Plantaris and external head of the Gastroc- nemius. Internally, above the joint, by the Semimembranosus, Semitendinosus, Gracilis, and Sartorius; below the joint, by the inner head of the Gastrocnemius. Above, it is limited by the apposition of the inner and outer hamstring muscles; beloAV, by the junction of the two heads of the Gastrocnemius. The floor is formed by the lower part of the posterior surface of the shaft of the femur, the posterior 390 ARTERIES. ligament of the knee joint, the upper end of the tibia, and the fascia covering the Popliteus muscle, and the space is covered in by the fascia lata. Contents. It contains the popliteal vessels and their branches, together with the termination of the external saphena vein, the internal and external popliteal nerves and their branches, the small sciatic nerve, the articular branch from the obturator nerve, a feAV small lymphatic glands, and a considerable quantity of loose adipose tissue. Position of contained parts. The internal popliteal nerve descends in the middle line of the space, lying superficial, and a little external to the vein and artery. The external popliteal nerve descends on the outer side of the space, lying close to the tendon of the Biceps muscle. More deeply at the bottom of the space are the popliteal vessels, the vein lying superficial and a little external to the artery, to which it is closely united by dense areolar tissue; sometimes the vein is placed on the inner instead of the outer side of the artery ; or the vein may be double, the artery then lies betAveen them, the tAvo veins being usually connected by short transverse branches. More deeply, and close to the surface of the bone, is the popliteal artery, and passing off from it at right angles are its articular branches. The articular branch from the obturator nerve descends upon the popliteal artery to supply the knee; and deeply in the space is an articular filament occasionally derived from the great sciatic nerve. The popliteal lymphatic glands, four or five in number, are found surrounding the artery; one usually lies superficial to the vessel, another is situated betAveen it and the bone, and the rest are placed on either side of it. In health, these glands are small; but when enlarged and indu- rated from inflammation, the pulsation communicated to them from the popliteal artery makes them resemble so closely an aneurismal tumor, that it requires a very careful examination to discriminate between them. The Popliteal Artery (Fig. 212), in its course downAvards from the aperture in the Adductor magnus, to the loAver border of the Popliteal muscle, rests first on the inner, and then on the posterior surface of the femur; in the middle of its course, on the posterior ligament of the knee joint; and below on the fascia covering the Popliteus muscle. Superficially, it is covered, above, by the Semimembranosus; in the middle of its course, by a quantity of fat, which separates it from the deep fascia and integument; and below% it is overlapped by the Gastrocnemius, Plan- taris, and Soleus muscles, the popliteal vein and the internal popliteal nerve. The popliteal vein, which is intimately attached to the artery,, lies superficial and external to it, until near its termination, Avhen it crosses it and lies to its inner side. The popliteal nerve is still more superficial and external, crossing, however, the artery below the joint, and lying on its inner side. Laterally, it is bounded by the muscles which form the boundaries of the popliteal space. Peculiarities in point of division. Occasionally the popliteal artery divides prematurely into its terminal branches; this division occurs most frequently opposite the knee joint. Unusual branches. ^ This artery sometimes divides into the anterior tibial and peroneal, the posterior tibial being wanting, or very small. In a single case, this artery divided into three branches, the anterior and posterior tibial, and peroneal. Surgical Anatomy. Ligature of the popliteal artery is required in cases of wound of that vessel, but for aneurism of the posterior tibial, it is preferable to tic the superficial femoral. The popliteal may be tied in the upper or lower part of its course; but in the middle of the space the operation is attended with considerable difficulty, from the great depth of the artery, and from the extreme degree of tension of its lateral boundaries. In order to expose the vessel in the upper part of its course, the patient should be placed in the prone position, with the limb extended. An incision about three inches in length should then be made through the integument, along the posterior margin of the Semimem- branosus, and the fascia lata having been divided, this muscle must be drawn inwards, when the pulsation of the vessel will be detected with the finger; the nerve lies on the outer or fibular side of the artery, the vein, superficial and also to its outer side; having cautiously separated it from the artery, the aneurism-needle should be passed around the latter vessel from Avithout inwards. To expose the vessel in the lower part of its course, where the artery lies between the two heads of the Gastrocnemius, the patient should be placed in the same position as in POPLITEAL. 391 the preceding operation. An incision should then middle line, commencing opposite the bend of the external saphena vein and nerve. After dividing cellular membrane, the artery, vein, and nerve will be exposed, descending between the two heads of the Gastrocnemius. Some muscular branches of the popliteal should be avoided if possible, or if divided, tied immediately. The leg being now flexed, in order the more effectually to separate the two heads of the Gastrocnemius, the nerve should be drawn inwards and the vein outwards, and the aneurism-needle passed between the ar- tery and vein from without inward. The branches of the popliteal artery are Ar i f Superior. Muscular < T A . ^ , ( Interior or Sural. Superior external articular. Superior internal articular. Azygos articular. Inferior external articular. Inferior internal articular. The Superior Aluscular Branches, Uvo or three in number, arise from the upper part of the popliteal artery, and are distributed to the Flexor muscles of the leg and the Vastus externus; anastomosing Avith the inferior perforating, and terminal branches of the profunda. The Inferior Muscular (Sural) are two large branches Avhich are distributed to the two heads of the Gastrocnemius and Plan- taris muscles. They arise from the popliteal artery opposite the knee joint. Cutaneous branches descend on each side and in the middle of the limb, between the Gastrocnemius and integument ; they arise separately from the popliteal artery, or from some of its branches, and supply the integu- ment of the calf. The Superior Articular Arteries, tAvo in number, arise one on either side of the popliteal, and wind around the femur immediately above its condyles to the front of the knee joint. The internal branch passes beneath the tendon of the Adductor magnus, and di- vides into tAvo, one of Avhich supplies the ^ astus internus, inosculating* -with the anas- tomotica magna and inferior internal arti- cular ; the other ramifies close to the surface of the femur, supplying it and the knee joint, and anastomosing with the superior external articular artery. The external branch passes above the outer condyle, beneath the tendon of the Biceps, and divides into a superficial and deep branch: the superficial branch supplies the Vastus be made through the integument in the knee joint, care being taken to avoid the lie deep fascia and separating some dense Fig. 212.—The Popliteal, Posterior Tibial, and Peroneal Arteries. 392 ARTERIES. externus, and anastomoses with the descending branch of the external circumflex artery; the deep branch supplies the lower part of the femur and knee joint, and forms an anastomotic arch across the bone with the anastomotic artery. The Azygos Articular is a small branch, arising from the popliteal artery oppo- site the bend of the joint. It pierces the posterior ligament, and supplies the liga- ments and synovial membrane in the interior of the articulation. The Inferior Articular Arteries, tw-o in number, arise from the popliteal, beneath the Gastrocnemius, and wind round the head of the tibia, below the joint. The internal one passes beloAv the inner tuberosity, beneath the internal lateral ligament, at the anterior border of which it ascends to the front and inner side of the joint, to supply the head of the tibia and the articulation of the knee. The external one passes outAvards above the head of the fibula, to the front of the knee joint, lying in its course beneath the outer head of the Gastrocnemius, the external lateral ligament, and the tendon of the Biceps muscle, and divides into branches, which anastomose Avith the artery of the opposite side, the superior articular, and the recurrent branch of the anterior tibial. Anterior Tibial Artery. The anterior tibial artery commences at the bifurcation of the popliteal, at the lower border of the Popliteus muscle, passes forAvards between the tAvo heads of the Tibialis posticus, and through the aperture left between the bones at the upper part of the interosseous membrane, to the deep part of the front of the leg; it then descends on the anterior surface of the interosseous ligament and of the tibia to the front of the ankle joint, where it lies more superficial, and becomes the dorsalis pedis. A line draAvn from the inner side of the head of the fibula to midAvay betwreen the tAvo malleoli, will be parallel with the course of this artery. Relations. In the upper two-thirds of its extent, it rests upon the interosseous ligament, to which it is connected by delicate fibrous arches throAvn across it. In the loAver third, upon the front of the tibia, and the anterior ligament of the ankle joint. In the upper third of its course, it lies betAveen the Tibialis anticus and Extensor longus digitorum : in the middle third, between the Tibialis anticus and Extensor proprius pollicis. In the loAver third it is crossed by the tendon of the Extensor proprius pollicis, and lies between it and the innermost tendon of the Extensor longus digitorum. It is covered, in the upper two-thirds of its course, by the muscles which lie on either side of it, and by the deep fascia : in the lower third, by the integument, annular ligament, and fascia. The anterior tibial artery is accompanied by tAvo veins (vena comites), which lie one on either side of the artery ; the anterior tibial nerve lies at first to its outer side, and about the middle of the leg is placed superficial to it; at the lower part of the artery the nerve is on the outer side. Plan of the Relations of the Anterior Tibial Artery. In front. Integument, superficial and deep fascia. Tibialis anticus. Extensor longus digitorum. Extensor proprius pollicis. Anterior tibial nerve. Inner side. f . \ Outer side. Tibialis anticus. ,!^nor Anterior tibial nerve. Extensor proprius pollicis. \ ilblal* J Extensor longus digitorum. y Extensor proprius pollicis. Behind. Interosseous membrane. Tibia. Anterior ligament of ankle joint. Peculiarities in Size. This vessel may be diminished in size, or it may be deficient to a ANTERIOR TIBIAL. 393 Fig. 213.—Surgical Anatomy of the Anterior Tibial and Dorsalis Pedis Arteries. rrreater or less extent, or it may be entirely wanting, its place being supplied by perforatin branches from the posterior tibial, or by the anterior division of the peroneal artery. Course. This artery occasionally deviates in its course towards the fibular side of the leg, regaining its usual position beneath the annular ligament at the front of the ankle. In two instances, this vessel has approached the surface iii the middle of the leg, from this point onwards being covered merely by the integument and fascia. Surgical Anatomy. The anterior tibial artery may be tied in the upper or lower part of the leg. In the upper part, the operation is attended with great diffi- culty, on account of the depth of the vessel from the surface. An incision, about four inches in length, should be made through the integument, midway between the spine of the tibia and the outer margin of the fibula, the fascia and intermuscular septum between the Tibialis anticus and Extensor communis digitorum being divided to the same extent. The foot must be flexed to relax these muscles, and they must be separated from each other by the finger. The artery is then exposed, deeply seated, lying upon the interosseous membrane, the nerve lying externally, and one of the ventc comites on either side; these must be separated from the artery before the aneurism- needle is passed around it. To tie this vessel in the lower third of the leg above the ankle joint, an incision about three inches in length should be made through the integument be- tween the tendons of the Tibialis anticus and Exten- sor proprius pollicis muscles, the deep fascia being divided to the same extent; the tendon on either side should be held aside, when the vessel will be seen lying upon the tibia, with the nerve superficial to it, and one of the vense comites on either side. In order to secure this vessel over the instep, an incision should be made on the fibular side of the tendon of the Extensor proprius pollicis, between it and the innermost tendon of the long Extensor : the deep fascia having been divided, the artery will be exposed, the nerve lying either superficial to it or to its outer side. The branches of the anterior tibial artery are Recurrent tibial. Muscular. Internal malleolar. External malleolar. The Recurrent Branch arises from the ante- rior tibial as soon as that vessel has passed through the interosseous space; it ascends in the Tibialis anticus muscle, and ramifies on the front and sides of the knee joint, anasto- mosing with the articular branches of the popli- teal. The Muscular Branches are numerous; they are distributed to the muscles which lie on either side of this vessel, some piercing the deep fascia to supply the integument, others passing through the interosseous membrane, and anastomosing with branches of the poste- rior tibial and peroneal arteries. i\nt*r 391 ARTERIES. The Malleolar Arteries supply the ankle joint. The internal arises about two inches above the articulation, passes beneath the tendon of the Tibialis anticus to the inner ankle, upon which it ramifies anasto- mosing with branches of the posterior tibial and internal plantar arteries. The external passes beneath the tendons of the Extensor longus digitorum and Extensor proprius pollicis, and supplies the outer ankle, anastomosing with the anterior peroneal artery and with ascending branches from the tarsea branch of the dorsalis pedis. Dorsalis Pedis Artery. The dorsalis pedis, the continuation of the anterior tibial, passes forwards from the bend of the ankle along the tibial side of the foot to the back part of the first interosseous space, where it divides into two branches, the dorsalis hallucis and communicating. Relations. This vessel in its course forAvards rests upon the astragalus, scaphoid and internal cuneiform bones, and the ligaments connecting them, being covered by the integument and fascia, and crossed near its termination by the innermost tendon of the Extensor brevis digitorum. On its tibial side is the tendon of the Extensor proprius pollicis ; on its fibular side, the innermost tendon of the Ex- tensor longus digitorum. It is accompanied by two veins, and by the anterior tibial nerve, which lies on its outer side. Plan of the Relations of the Dorsalis Pedis Artery. fn fron t. Integument and fascia. Innermost tendon of Extensor Brevis digitorum. Fibular side. Tibial side. I Dorsalis \ Extensor proprius pollicis. e 1S> / Extensor longus digitorum. Anterior tibial nerve. Behind. Astragalus, Scaphoid, Internal cuneiform, and their ligaments. Peculiarities in Size. The dorsal artery of the foot may be larger than usual, to compen- sate tor a deficient plantar artery; or it may be deficient in its terminal branches to the toes, which are then derived from the internal plantar; or its place may be supplied altogether by a large anterior peroneal artery. /W,W This artery frequently curves outwards, lying external to the line between the middle ot the ankle and the back of the first interosseous space. Surgical Anatomy. This artery may be tied, by making an incision through the integu- ment, between two and three inches in length, on the fibular side of the tendon of the Ex- tensor proprius pollicis, in the interval between it and the inner border of the short Extensor muscle. Ihe incision should not extend further forwards than the back part of the first interosseous space as the artery divides in this situation. The deep fascia being divided to the same extent, the artery will be exposed, the nerve lying upon its outer side. Branches. The branches of the dorsalis pedis are, the -Lciisca. TnterosseEe Metatarsea. Dorsalis hallucis. Communicating. The Tarsea Artery arises from the dorsalis pedis, as that vessel crosses the sca- phoid bone; it passes in an arched direction outwards, lying upon the tarsal bones, and covered by the Extensor brevis digitorum: it supplies that muscle and the arti- culations of the tarsus, and anastomoses with branches from the metatarsea, external malleolar, peroneal, and external plantar arteries. POSTERIOR TIBIAL. 395 The Metatarsea arises a little anterior to the preceding; it passes outwards to the outer part of the foot, over the bases of the metatarsal bones, beneath the tendons of the short Extensor, its direction being influenced by its point of origin ; and it anastomoses with the tarsea and external plantar arteries. This vessel gives off three branches, the interossei, which pass forwards upon the three outer Dor- sal interossei muscles, and, in the clefts between the toes, divide into two dorsal collateral branches for the adjoining toes. At the back part of each interosseous space, these vessels receive the posterior perforating branches from the plantar arch ; and at the forepart of each interosseous space, they are joined by the ante- rior perforating branches, from the digital arteries. The outermost interosseous artery gives off a branch Avhich supplies the outer side of the little toe. The Dorsalis Hallucis runs forwards along the outer surface of the first meta- tarsal bone, and, at the cleft between the first and second toes, divides into two branches, one of which passes inwards, beneath the tendon of the Flexor longus pollicis, and is distributed to the inner border of the great toe; the other branch bifurcating to supply the adjoining sides of the great and second toes. The Communicating Artery dips doAvn into the sole of the foot, between the two heads of the first Dorsal interosseous muscle, and inosculates with the termination of the external plantar artery, to complete the plantar arch. It here gives off tAvo digital branches ; one runs along the inner side of the great toe, on its plantar surface; the other passes forAvards along the first metatarsal space, and bifurcates for the supply of the adjacent sides of the great and second toes. Posterior Tibial Artery. The posterior tibial is an artery of large size, Avhich extends obliquely doAvnAvards from the loAver border of the Popliteus muscle, along the tibial side of the leg, to the fossa betAveen the inner ankle and the heel, Avhere it divides beneath the origin of the Abductor pollicis, into the internal and external plantar arteries. At its origin it lies opposite the interval betAveen the tibia and fibula; as it descends, it approaches the inner side of the leg, lying behind the tibia, and, in the loAver part of its course, is situated midAvay betAveen the inner malleolus and the tuberosity of the os ealcis. Relations. It lies successively upon the Tibialis posticus, the Flexor longus digi- torum, and beloAv, upon the tibia and back part of the ankle joint. It is covered by the intermuscular fascia, Avhich separates it, above, from the Gastrocnemius and Soleus muscles. In the lower third, Avhere it is more superficial, it is covered only by the integument and fascia, and runs parallel Avith the inner border of the tendo Achillis. It is accompanied by tAvo Areins, and by the posterior tibial nerve, which lies at first to the inner side of the artery, but soon crosses it, and is, in the greater part of its course, on its outer side. Plan of the Relations of the Posterior Tibial Artery. In front. Tibialis posticus. Flexor lomrus di»itorum. Tibia. Ankle joint. Inner side. , _ Outer side. Posterior tibial nerve, ( -Interior Posterior tibial ner\'e, upper third. \ libial. loAA'er two-thirds. Behind. Gastrocnemius. Soleus. Deep fascia and integument. Behind the Liner Ankle, the tendons and bloodvessels arc arranged in the folloAv- ing order, from Avithin outAvards : First, the tendons of the Tibialis posticus and 396 ARTERIES. Flexor longus digitorum, lying in the same groove, behind the inner malleolus, the former being the most internal. External to these is the posterior tibial artery, having a vein on either side ; and, still more externally, the posterior tibial nerve. About half an inch nearer the heel is the tendon of the Flexor longus pollicis. Peculiarities in Size. The posterior tibial is not unfrequently smaller than usual, or absent its place being compensated for by a large peroneal artery, which passes inwards at the lower end of the tibia, and either joins the small tibial artery, or continues alone to the sole of the foot. Surgical Anatomy. The a judication of a ligature to the posterior tibial may be required in cases of wound of the sole of the foot, attended with great hemorrhage, when the vessel should be tied at the inner ankle. ' In cases of wound of the posterior tibial itself, it will be necessary to enlarge the wound so as to expose the vessel at the wounded point (excepting where the vessel is injured by a punctured wound from the front of the leg). In cases of aneurism from wound of the artery low down, the vessel should be tied in the middle of the leg. But in aneurism of the posterior tibial high up, it would be better to tie the femoral artery. To tie the posterior tibial artery at the ankle, a semilunar incision should be made through the integument, about two inches and a half in length, midway between the heel and inner ankle, but a little nearer the latter. The subcutaneous cellular membrane having been divided, a strong and dense fascia, the internal annular ligament, is exposed. This ligament is con- tinuous above with the deep fascia of the leg, covers the vessels and nerves, and is intimately adherent to the sheaths of the tendons. This having been cautiously divided upon a director, the sheath of the vessels is exposed, and being opened, the artery is seen with one of the venae comites on each side. The aneurism-needle should be passed around the vessel from the heel towards the ankle, in order to avoid the posterior tibial nerve, care being at the same time taken not to include the venae comites. The vessel may also be tied in the lower third of the leg, by making an incision about three inches in length, parallel with the inner margin of the tendo Achillis. The internal saphena vein being carefully a Avoided, the two layers of fascia must be divided upon a director, Avhen the artery is exposed along the inner margin of the Flexor longus digitorum, with one of its venae comites on either side, and the nerve lying external to it. To tie the posterior tibial in the middle of the leg is a very difficult operation, on account of the great depth of the vessel from the surface, and from its being covered in by the Gastroc- nemius and Soleus muscles. The patient being placed in the recumbent position, the injured limb should rest on its outer side, the knee being partially bent, and the foot extended, so as to relax the muscles of the calf. An incision about four inches in length should then be made through the integument, along the inner margin of the tibia, taking care to aAoid the internal saphena vein. The deep fascia having been divided, the margin of the Gastrocnemius is exposed, and must be drawn aside, and the tibial attachment of the Soleus divided, a direc- tor being previously passed beneath it. The artery may now be felt pulsating beneath the deep fascia, about an inch from the margin of the tibia. The fascia having been divided, and the limb placed in such a position as to relax the muscles of the calf as much as possible, the veins should be separated from the artery, and the aneurism-needle passed around the vessel from without inwards, so as to avoid wounding the posterior tibial nerve. The branches of the posterior tibial artery are, the Peroneal. Nutritious. Muscular. Communicating. Internal calcanean. The Peroneal Artery lies, deeply seated, along the back part of the fibular side of the leg. It arises from the posterior tibial, about an inch beloAV the lower bor- der of the Popliteus muscle, passes obliquely outwards to the fibula, and then descends along the inner border of this bone to the lower third of the leg, where it gives off the anterior peroneal. It then descends across the articulation, between the tibia and fibula, to the outer side of the os ealcis, supplying the neighboring muscles and back of the ankle, and anastomosing with the external malleolar, tarsal, and external plantar arteries. Relations. This vessel rests at first upon the Tibialis posticus, and in the PERONEAL. 397 greater part of its course, in the fibres of the Flexor longus pollicis, in a Groove between the interosseous ligament and the bone. It is covered, in the upper part of its course, by the Soleus and deep fascia; below, by the Flexor longus pollicis. Plan of the Relations of the Peroneal Artery. In front. Tibialis posticus. Flexor longus pollicis. Behind. Soleus. Deep fascia. Flexor longus pollicis. Peculiarities in Origin. The peroneal artery may arise three inches below the popli- teus, or from the posterior tibial high up, or even from the popliteal. Its Size is more frequently increased than diminished, either reinforcing the posterior tibial by its junction with it, or by altogether taking the place of the posterior tibial, in the lower part of the leg and foot, the latter vessel only existing as a short muscular branch. In those rare cases, where the peroneal artery is smaller than usual, a branch from the posterior tibial supplies its place, and a branch from the anterior tibial compen- sates for the diminished anterior peroneal artery. In one ease, the peroneal artery has been found entirely wanting. The anterior peroneal is sometimes enlarged, and takes the place of the dorsal artery of the foot. The peroneal artery, in its course, gives off branches to the Soleus, Tibialis posticus, Flexor longus pollicis, and Peronei muscles, and a nutrient branch to the fibula. The Anterior Peroneal pierces the interosseous membrane, about tAvo inches above the outer malleolus, to reach the forepart of the leg, and, passing down beneath the peroneus tertius to the outer ankle, ramifies on the front and outer side of the tarsus, anastomosing Avith the external malleolar and tarsal arteries. The Nutritious Artery of the tibia arises from the posterior tibial near its origin, and after supplying a feAV muscular branches, enters the nutritious canal of that bone, which it traverses obliquely from above downwards. This is the largest nutrient artery of bone in the body. The Muscular Brandies are distributed to the Soleus and deep muscles along the back of the leg. The Communicating Branch to the peroneal passes transversely across the back of the tibia, about tAvo inches above its loAver end, passing beneath the Flexor longus pollicis. The Internal Calcancan consists of several large branches, which arise from the posterior tibial just before its division ; they are distributed to the fat and integument behind the tendo Achillis and about the heel, and to the muscles on the inner side of the sole, anastomosing with the posterior peroneal and internal malleolar arteries. The Internal Plantar Artery, much smaller than the external, passes forAvards along the inner side of the foot. It is at first situated above the Adductor pollicis. and then betAveen it and the Flexor brevis digitorum, both of which it supplies. At the base of the first metatarsal bone, where it has become much diminished in size, it passes along the inner border of the great toe, inosculating with its digital branches. The External Plantar Artery, much larger than the internal, passes obliquely outAvards and forwards to the base of the fifth metatarsal bone. It then turns obliquely inAvards to the interval betAveen the bases of the first and second meta- 0uter side. Fibula. 398 ARTERIES. tarsal bones, Avhere it inosculates Avith the communicating branch from the dorsalis pedis artery, thus completing the plantar arch. As this artery passes outwards, it is at first placed betAveen the os ealcis and Abductor pollicis, and then between the Flexor brevis digitorum and Flexor accessorius ; and as it passes forAvards to the base of the little toe, it lies more superficial, betAveen the Flexor brevis digitorum and Abductor minimi digiti, covered by the deep fascia and integument. The remaining portion of the vessel is deeply situated ; it extends from the base of the metatarsal bone of the little toe to the back part of the first interosseous space, and forms the plantar arch ; it is convex forAvards, lies upon the Interossei Fig. 214.—The Plantar Arteries. Fig. 215.—The Plantar Arteries. Superficial A'iew. Deep View. muscles, opposite the tarsal ends of the metatarsal bones, and is covered by the Adductor pollicis, the flexor tendons of the toes, and the Lumbricales. Branches. The plantar arch, besides distributing numerous branches to the muscles, integument, and fasciae in the sole, gives off the following branches :— Posterior perforating. Digital—Anterior perforating. The Posterior Perforating are three small branches, Avhich ascend through the back part of the three outer interosseous spaces, betAveen the heads of the Dorsal interossei muscles, and anastomose with the interosseous branches from the meta- tarsal artery. The Digital Brandies are four in number, and supply the three outer toes and half the next. The first passes outwards from the outer side of the plantar arch, and is distributed to the outer side of the little toe, passing in its course beneath the Adductor and short Flexor muscles. The second, third, and fourth run for- Avards along the metatarsal spaces, and on arriving at the clefts between the toes. divide into collateral branches, which supply the adjacent sides of the three outer toes and the outer side of the second. At the bifurcation of the toes, each digital artery sends upwards, through the forepart of the corresponding metatarsal space, PLANTAR; PULMONARY. 399 a small branch, Avhich inosculates with the interosseous branches of the metatarsal artery. These are the anterior perforating arteries. From the arrangement already described of the distribution of the vessels to the toes, it will be seen that both sides of the three outer toes, and the outer side of the second toe, are supplied by branches from the plantar arch; both sides of the great toe, and the inner side of the second, being supplied by the dorsal artery of the foot. Pulmonary Artery. The pulmonary artery conveys the dark impure venous blood from the right side of the heart to the lungs. It is a short Avicle vessel, about tAvo inches in length, arising from the left side of the base of the right A^entricle, in front of the ascending aorta. It ascends obliquely upAvards, backwards, and to the left side, as far as the under surface of the arch of the aorta, where it divides into tAvo branches of nearly equal size, the right and left pulmonary arteries. Relations. The greater part of this vessel is contained, together Avith the aorta, in the pericardium, being inclosed Avith it in a tube of serous membrane, continued upwards from the base of the heart, and has attached to it, above, the fibrous layer of this membrane. Eehind, it rests at first upon the ascending aorta, and higher up in front of the left auricle. On either side of its origin is the appendix of the corresponding auricle and a coronary artery; and higher up it passes to the left side of the ascending aorta. A little to the left of its point of bifurcation it is connected to the under surface of the arch by a short fibrous cord, the remains of a vessel peculiar to fcetal life, the ductus arteriosus. The Right Pulmonary Artery, longer and larger than the left, runs horizontally outwards, behind the ascending aorta and superior vena cava, to the root of the right lung, Avhere it divides into tAvo branches, of Avhich the lower, the larger, supplies the loAver lobe, the upper giving a branch to the middle lobe. The Left Pulmonary Artery, shorter but somcAvhat smaller than the right, passes horizontally in front of the descending aorta and left bronchus to the root of the left lung, Avhere it divides into tAvo branches for the tAvo lobes. Of the Veins. THE Veins are the vessels Avhich serve to return the blood from the capillaries of the different parts of the body to the heart. They consist of two distinct sets of vessels, the pulmonary and systemic. The Pulmonary Veins, unlike other vessels of this kind, contain arterial blood, which they return from the lungs to the left auricle of the heart. The Systemic Veins return the venous blood from the body generally to the right auricle of the heart. The Portal Vein, an appendage to the systemic venous system, is confined to the abdominal cavity, returning the venous blood from the viscera of digestion, and carrying it to the liver by a single trunk of large size, the vena portae. From this organ the same blood is conveyed to the inferior vena cava by means of the hepatic veins. The veins, like the arteries, are found in nearly every tissue of the body; they commence by minute plexuses, Avhich communicate with the capillaries, the branches from which, uniting together, constitute trunks, which increase in size as they pass towards the heart, from the termination of larger branches in them. The veins are larger and altogether more numerous than the arteries; hence the entire capacity of the venous system is much greater than the arterial; the pulmonary veins excepted, which do not exceed in capacity the pulmonary arteries. From the combined area of the smaller venous branches being greater than the main trunks, it results that the venous system represents a cone, the summit of which corresponds to the heart, its base to the circumference of the body. _ In form, the veins are not perfectly cylindrical, like the arteries, their walls being collapsed when empty, and the uniformity of their surface being interrupted at intervals by slight contractions, which indicate the existence of valves in their interior. They usually retain, however, the same calibre as long as they receive no neighboring branches. The veins communicate very freely with one another, especially in certain regions of the body; and this communication exists betAveen the larger trunks as Avell as betAveen the smaller branches. Thus, in the cavity of the cranium, and between the veins of the neck, where obstruction of the cerebral venous system would be attended with imminent danger, Ave find that the sinuses and larger veins have large and very frequent anastomoses. The same free communication exists betAveen the veins throughout the whole extent of the spinal canal, and between the veins composing the various venous plexuses in the abdomen and pelvis, as the spermatic, uterine, vesical, prostatic, etc. The veins are subdivided into three sets: superficial, deep, and sinuses. The Supcrficied or Cutaneous Veins are found betAveen the layers of superficial fascia, immediately beneath the integument: they return the blood from these structures, and communicate with the deep veins by perforating the deep fascia. The Deep Veins accompany the arteries, and are usually inclosed in the same sheath with those vessels. In the smaller arteries, as the radial, ulnar, brachial, tibial, peroneal, they exist generally in pairs, one lying on each side of the vessel, and are called vence comites. The larger arteries, as the axillary, subclavian, popliteal, and femoral, have usually only one accompanying vein. In certain organs of the body, hoAvever, the deep veins do not accompany the arteries; tor instance, the veins in the skull and spinal canal, the hepatic veins in the liver, and the larger veins returning blood from the osseous tissue. Sinuses are venous channels, which, in their structure and mode of distribution, differ altogether from the veins. They are found only in the interior of the skull, GENERAL ANATOMY. 401 and are formed by a subdivision of the layers of the dura mater; their outer coat consisting of fibrous tissue, their inner of a serous membrane continuous with the serous membrane of the veins. Veins are thinner in structure than the arteries, and possessed of considerable strength. The superficial veins usually have thicker coats than the deep veins, and the veins of the loAver limb are thicker than those of the upper. Areins are composed of three coats, internal, middle, and external. The Internal is an epithelial and elastic coat, consisting of an epithelial lining supported on several laminae of longitudinal elastic fibres. It is less brittle in structure than the same coat in the arteries, and its laminae are seldom fenestrated. The Middle or Contractile Coat, thinner than that of the arteries, consists of numerous alternating layers of muscular and elastic fibres. The muscular fibres are disposed in a circular form around the vessel, intermixed with areolar tissue and elastic fibres. The elastic coat consists of well-developed elastic fibres, reti- culating in a longitudinal direction. This coat is best marked in the splenic and portal veins, and appears to be wanting in the hepatic part of the vena cava, in the hepatic and subclavian veins. Muscular tissue is also wanting in the veins : 1. Of the maternal part of the placenta. 2. In most of the cerebral veins and sinuses of the dura mater. 3. In the veins of the retina. 4. In the veins of the cancellous tissue of bones. 5. In the venous spaces of the corpora cavernosa. The veins of the above-mentioned parts consist of an internal epithelial lining, supported on one or more layers of areolar tissue. On the other hand, muscular tissue is abundantly developed in the Areins of the gravid uterus, being found in all three coats; and in the venae cavae and pulmonary vreins, it is prolonged on to them from the auricles of the heart. The External or Areolar Fibrous Coat consists of areolar tissue and longi- tudinal elastic fibres, it also contains in some of the larger veins a longitudinal network of non-striated muscular fibres, as in the Avhole length of the inferior vena cava, the renal, azygos, and external iliac veins, and in all the large trunks of the portal venous system, and in the trunks of the hepatic veins. Most veins are provided Avith valves, A\liich serve to prevent the reflux of the blood. They are formed by a reduplication of the lining membrane, strengthened by a little fibrous tissue ; their form is semilunar, they are attached by their convex edge to the Avail of the vein ; the concave margin is free, directed in the course of the A'enous current, and lies in close apposition with the Avail of the vein as long as the current of blood takes its natural course ; if, however, any regurgitation takes place, the valves become distended, their opposed edges are brought into con- tact, and the current is intercepted. Most commonly two such valves are found, placed opposite one another, more especially in the smaller veins, or in the larger trunks at the point Avhere they are joined by small branches; occasionally there are three, and sometimes only one. The Avail of the vein immediately above the point of attachment of each segment of the valve, is expanded into a pouch or sinus, which gives to the vessel, Avhen injected or distended Avith blood, a knotted appearance. The valves are very numerous in the veins of the extremities, espe- cially the loAver ones, these vessels having to conduct the blood against the force of gravity. They are absent in the very small veins, also in the venae cavae, the hepatic vein, portal vein and its branches, the renal, uterine, and ovarian veins. A feAV valves are found in the spermatic veins, and one also at their point of junction Avith the renal vein and inferior cava in both sexes. The cerebral and spinal veins, the veins of the cancellated tissue of bone, the pulmonary veins, and the umbilical vein and its branches, are also destitute of valves. They are occasionally found, feAV in number, in the venae azygos and intercostal veins. The veins are supplied Avith nutrient vessels, vasa vasorum, like the arteries: but nerves are not generally found distributed upon them, the only vessels upon which they have at present been traced being the inferior vena cava and cerebral veins. 28 402 VEINS. The veins may be arranged into three groups. 1. Those of the head and neck, upper extremity', and thorax, which terminate in the superior vena cava. 2. Those of the lower limb, pelvis, and abdomen, Avhich terminate in the inferior vena cava. 3. The cardiac veins, which open directly into the right auricle of the heart. Veins of the Head and Neck. The veins of the head and neck may be subdivided into three groups. 1. The veins of the exterior of the head. 2. The veins of the neck. 3. The veins of the diploe and interior of the cranium. The veins of the exterior of the head are the Facial. Temporo-maxillary. Temporal. Posterior auricular. Internal Maxillary. Occipital. Fig. 216.—Veins of the Head and Neck. The Facial Vein passes obliquely across the side of the face, extending from the inner angle of the orbit, downwards and outAvards, to the anterior margin of the Masseter muscle. It lies to the outer side of the facial artery, and is not so OF THE HEAD AND FACE. 403 tortuous as that vessel. It commences in the frontal region, where it is called the frontal vein ; at the inner angle of the eye it has received the name of the angular vein; and from this point to its termination, the facial vein. The frontal vein commences on the anterior part of the skull, by a venous plexus, which communicates with the anterior branches of the temporal vein; the veins converge to form a single trunk, which descends along the middle line of the forehead parallel with the vein of the opposite side, and unites Avith it at the root of the nose by a transverse trunk, called the nasal arch. Occasionally the frontal veins join to form a single trunk Avhich bifurcates at the root of the nose into the two angular veins. At the nasal arch the branches diverge, and run along the side of the root of the nose. The frontal vein as it descends upon the forehead, receives the supraorbital vein ; the dorsal veins of the nose terminate in the nasal arch; and the angular vein receives, on its inner side, the veins of the ala nasi, on its outer side,_ the superior palpebral vein ; it moreover communicates with the ophthalmic vein, which establishes an important anastomosis between this vessel and the cavernous sinus. The facial vein commences at the inner angle of the orbit, being a continuation of the angular vein. It passes obliquely downwards and outwards, beneath the great Zygomatic muscle, descends along the anterior border of the Masseter, crosses over the body of the lower jaw, with the facial artery, and, passing obliquely outwards and backwards, beneath the Platysma and cervical fascia, unites with a branch of communication from the temporo-maxillary vein, to form a trunk of large size, Avhich enters the internal jugular. Branches. The facial vein receives, near the angle of the mouth, communicating branches from the pterygoid plexus. It is also joined by the inferior palpebral, the superior and inferior labial veins, the buccal veins from the cheek, and the masseteric veins. BeloAv the jaw, it receives the submental, the inferior palatine, which returns the blood from the plexus around the tonsil and soft palate; the submaxillary vein, which commences in the submaxillary gland; and lastly, the ranine vein. The Temporal Vein commences by a minute plexus on the side and vertex of the skull, Avhich communicates Avith the frontal vein in front, the corresponding vein of the opposite side, and the posterior auricular and occipital veins behind. From this netAvork, anterior and posterior branches are formed, Avhich unite above the zygoma, forming the trunk of the vein. This trunk is joined in this situation by a large vein, the middle temporal, which receives the blood from the substance of the temporal muscle and pierces the fascia at the upper border of the zygoma. The temporal vein then descends betAveen the external auditory meatus and the condyle of the jaAv, enters the substance of the parotid gland, and unites with the internal maxillary vein, to form the temporo-maxillary. Branches. The temporal vein receives in its course some parotid veins, an articular branch from the articulation of the jaw, anterior auricular veins from the external ear, and a vein of large size, the transverse facial, from the side of the face. The Internal Maxillary Vein is a vessel of considerable size, receiving branches which correspond Avith those derived from the internal maxillary artery. Thus it receives the middle meningeal veins, the deep temporal, the pterygoid, masseteric, and buccal, some palatine veins, and the inferior dental. These branches form a large plexus, the pterygoid, Avhich is placed betAveen the Temporal and External pterygoid, and partly between the Pterygoid muscles. This plexus communicates very freely Avith the facial vein, and with the cavernous sinus, by branches through the base of the skull. The trunk of the vein then passes backwards, behind the neck of the loAver jaAV, and unites Avith the temporal vein, forming the temporo- maxillary. The Temporo-maxillary Vein, formed by the union of the temporal and internal maxillary veins, descends in the substance of the parotid gland, betAveen the ramus of the jaAV and the Sterno-mastoid muscle, and divides jnto two branches, one of Avhich passes inwards to join the facial vein, the other is continuous 404 VEINS. with the external jugular. It receives near its termination the posterior auricular vein. The Posterior Auricular Vein commences upon the side of the head, by a plexus AArhich communicates Avith the branches of the temporal and occipital veins descending behind the external ear. It joins the temporo-maxillary, just before that vessel terminates in the external jugular. This vessel receives the stylo- mastoid vein, and some branches from the back part of the external ear. The Occipital Vein commences at the back part of the vertex of the skull, by a plexus in a similar manner Avith the other veins. It follows the course of the occipital artery, passing deeply beneath the muscles of the back part of the neck and terminates in the internal jugular, occasionally in the external jugular. As this vein passes opposite the mastoid process, it receives the mastoid vein, which establishes a communication Avith the lateral sinus. Veins of the Neck. The veins of the neck, Avhich return the blood from the head and face, are the External jugular. Anterior jugular. Posterior external jugular. Internal jugular. Vertebral. The External Jugular Vein receives the greater part of the blood from the exterior of the cranium and deep parts of the face, being a continuation of the temporo-maxillary and posterior auricular veins. It commences in the substance of the parotid gland, on a level with the angle of the lower jaAv, and runs perpen- dicularly down the neck, in the direction of a line drawn from the angle of the jaAv to the middle of the clavicle. In its course, it crosses the Sterno-mastoid muscle, and runs parallel with its posterior border as far as its attachment to the clavicle, where it perforates the deep fascia, and terminates in the subclavian vein, on the outer side of the internal jugular. As it descends the neck, it is separated from the Sterno-mastoid by the anterior layer of the deep cervical fascia, and is covered by the Platysma, the superficial fascia, and the integument. This vein is crossed about its centre by the superficial cervical nerve, and its upper half is_ accompanied by the auricularis magnus nerve. The external jugular vein varies in size, bearing an inverse proportion to that of the other veins of the neck: it is occasionally double. It is provided Avith tAvo valves, one being placed at its entrance into the subclavian vein, and a second in most cases about the middle of its course. _ These valves do not prevent the regurgitation of the blood, or the passage of injection from below upwards. Branches. _ This vein receives the occipital, the posterior external jugular, and, near its termination, the suprascapular and transverse cervical veins. It com- municates with the anterior jugular, and, in the substance of the parotid, receives a large branch of communication from the internal jugular. The Posterior External Jugular Vein returns the blood from the integument and superficial muscles in the upper and back part of the neck, lying between the Splenius and Trapezius muscles. It descends the back part of the neck, and opens into the external jugular just below the middle of its course. The Anterior Jugular j idn collects the blood from the integument and muscles m the middle of the anterior region of the neck. It passes down between the median line and the anterior border of the Sterno-mastoid, and, at the lower part of the neck, passes beneath that muscle to open into the subclavian vein, near the termination of the external jugular. This A'ein varies considerably in size, bearing almost always an inverse proportion to the external jugular. Most frequently there are two anterior jugulars, a right, and left; but occasion- OF THE NECK. 405 ally only one. This vein receives some laryngeal branches, and occasionally an inferior thyroid vein. Just above the sternum, the two anterior jugular veins communicate by a transverse trunk, which receives branches from the inferior thyroid veins. It also communicates Avith the external and Avith the internal jugular. The Internal Jugular Vein collects the blood from the interior of the cra- nium, from the superficial parts of the face, and. from the neck. It commences at the jugular foramen, in the base of the skull, being formed by the coalescence of the lateral and inferior petrosal sinuses. At its origin it is someAvhat dilated, and this dilatation is called the sinus or gulf of the internal jugular vein. It runs doAvn the side of the neck in a vertical direction, lying at first on the outer side of the internal carotid, and then on the outer side of the common carotid, and at the root of the neck unites with the subclavian vein, to form the vena innominata. The internal jugular vein, at its commencement, lies upon the Rectus lateralis, behind, and at the outer side of the internal carotid, and the eighth and ninth pairs of nerves ; lower (Ioavii, the vein and artery lie upon the same plane, the glosso-pharyngeal and hypoglossal nerves pass- ing fonvards betAveen them ; the pneumogastric descends between and behind them, in the same sheath; and the spinal accessory passes obliquely outwards, behind the vein. At the root of the neck the vein of the right side is placed at a little distance from the artery ; on the left side it usually crosses it at its loAver part. This vein is of considerable size, but A'arying in different individuals, the left one being usually the smallest. It is provided Avith two valves, which are placed at its point of termination, or from one to tAvo inches above it. Branches. This vein receives in its course, the facial, lingual, pharyngeal, superior and middle thyroid veins, and the occipital. At its point of junction Avith the branch common to the temporal and facial veins, it becomes greatly increased in size. The Lingual Veins commence on the dorsum, sides, and under surface of the tongue, and, passing backwards, folloAving the course of the lingual artery and its branches, terminate in the internal jugular. The Pharyngeal Vein commences in a minute plexus, the pharyngeal, at the back part and sides of the pharynx, and, after receiving meningeal branches, and some from the Vidian and spheno-palatine veins, terminates in the internal jugular. It occasionally opens into the facial, lingual, or superior thyroid vein. The Superior Thyroid Vein commences in the substance and on the surface of the thyroid gland, by branches corresponding with those of the superior thyroid artery, and terminates in the upper part of the internal jugular vein. The 3Iiddle Thyroid Vein collects the blood from the lower part of the lateral lobe of the thyroid gland, and, being joined by some branches from the larynx and trachea, terminates in the lower part of the internal jugular vein. The Vertebral Vein is described under another head. (See page 412.) Veins of the Diploe. The diploe of the cranial bones is channelled, in the adult, with a number of tortuous canals, which are lined by a more or less complete layer of compact tissue. The veins they contain are large and capacious, their Avails being thin, and formed only of epithelium, resting upon a layer of elastic tissue, and they present, at irregular intervals, pouch-like dilatations, or culs-de-sac, which serve as reservoirs for the blood. These are the veins of the diploe, and can only be displayed by removing the outer table of the skull. In adult life, as long as the cranial bones are distinct and separable, these veins are confined to the particular bones; but in old age, when the sutures are united, they communicate with each other, and increase in size. These vessels commu- nicate, in the interior of the cranium, with the meningeal veins, and with the sinuses of the dura mater; and on the exterior of the skull, with the veins of 406 VEINS. the pericranium. In the cranium they are divided into the fronted, Avhich opens into the supraorbital vein, by an aperture at the supraorbital notch ; the ante- rior temporal, which is confined chiefly to the frontal bone, and opens into one of the deep temporal veins, after escaping by an aperture in the great Aving of the Fig. 217.—Veins of the Diploe, as displayed by the Removal of the Outer Table of the Skull. sphenoid; the posterior temporal, which is confined to the parietal bone, termi- nates in the lateral sinus, by an aperture at the posterior inferior angle of the parietal bone; and the occipital, which is confined to the occipital bone, and opens either into the occipital vein, or the occipital sinus. Cerebral Veins. The Cerebral Veins are remarkable for the extreme thinness of their coats, from the muscular tissue in them being wanting, and for the absence of valves. They may be divided into two sets, the superficial, which are placed on the surface, and the deep veins, Avhich occupy the interior of the organ. The Superficial Cerebral Veins ramify upon the surface of the brain, being lodged m the sulci, between the convolutions, a few running across the convolu- tions. They receive branches from the substance of the brain, and terminate in the sinuses. They are named from the position they occupy, superior, inferior, internal, or external. The Superior Cerebral Veins, seven or eight in number on each side, pass forwards and inwards towards the great longitudinal fissure, where they receive the internal cerebral veins, which return the blood from the convolutions of the flat surface of the corresponding hemisphere ; passing obliquely forwards, they be- come invested with a tubular sheath of the arachnoid membrane, and open into the superior longitudinal sinus, in the opposite direction to the course of the blood. Ihe Inferior Anterior Cerebral Veins commence on the under surface of the anterior lobes of the brain, and terminate in the cavernous sinuses. The Inferior Lateral Cerebral Veins commence on the lateral parts of the hemispheres and at the base of the brain: they unite to form from three to five veins, which open into the lateral sinus from before backwards. The Inferior Median Cerebral Veins, which are very large, commence at the forepart of the under surface of the cerebrum, and from the convolutions of the posterior lobe, and terminate in the straight sinus behind the venae Galeni. CEREBRAL. 407 The Deep Cerebral, or Ventricular Veins (venae Galeni), are tAvo in number, one from the right, the other from the left ventricle. They are each formed by tAvo veins, the vena corporis striati, and the choroid vein. They pass back- Avards, parallel with one another, inclosed within the velum interpositum, and pass out of the brain at the great transverse fissure, betAveen the under surface of the corpus callosum and the tubercula quadrigemina, and enter the straight sinus. The Vena Corporis Striati commences in the groove betAveen the corpus striatum and thalamus opticus, receh'es numerous veins from both of these parts, and unites behind the anterior pillar of the fornix with the choroid vein, to -form one of the venfe Galeni. The Choroid Vein runs along the Avhole length of the outer border of the cho- roid plexus, receiving veins from the hippocampus major, the fornix, and corpus callosum, and unites, at the anterior extremity of the choroid plexus, with the vein of the corpus striatum. The Cerebellar Veins occupy the surface of the cerebellum, and are disposed in three sets, superior, inferior, and lateral. The superior pass forwards and inAvards, across the superior vermiform process, and terminate in the straight sinus: some open into the venae Galeni. The inferior cerebellar veins, of large size, run transversely outAvards, and terminate by tAvo or three trunks in the lateral sinuses. The lateral anterior cerebellar veins, terminate in the superior petrosal sinuses. Sinuses of the Dura Mater. The sinuses of the dura mater are venous channels, analogous to the veins, their outer coat being formed by the dura mater; their inner, by a continuation of the serous membrane of the veins. They are twelve in number, and are divided into two sets. 1. Those situated at the upper and back part of the skull. 2. The sinuses at the base of the skull. The former are the Superior longitudinal. Straight sinus. Inferior longitudinal. Lateral sinuses. Occipital sinuses. Fig. 218.—Vertical Section of the Skull, showing the Sinuses of the Dura Mater. The Superior Longitudinal Sinus occupies the attached margin of the falx cerebri. Commencing at the crista galli, it runs from before backAvards, grooving the inner surface of the frontal, the adjacent margins of the tAvo parietal^ and the 408 VEINS. superior division of the crucial ridge of the occipital bone, and terminates by dividing into the tAvo lateral sinuses. This sinus is triangular in form, narrow in front, and gradually increasing in size as it passes backwards. On examining its inner surface, it presents the internal openings of the cerebral vein, the apertures of Avhich are, for the most part, directed from behind forwards, and chiefly open at its back part, their orifices being concealed by fibrous areolae; numerous fibrous bands are also seen (chordae Willisii), which extend transversely across its inferior angle; and lastly, some small, Avhite, projecting bodies, the glandulae Pacchioni. This sinus receives the superior cerebral veins, numerous veins from the diploe and dura mater, and, at the posterior extremity of the sagittal suture, the parietal veins from the pericranium. The point where the superior longitudinal and lateral sinuses are continuous is called the confluence of the sinuses, or the torcular Herophili. D presents a con- siderable dilatation, of very irregular form, and is the point of meeting of six sinuses, the superior longitudinal, the two lateral, the tAvo occipital, and the straight. The Lnferior Longitudinal Sinus, more correctly described as the inferior longi- tudinal vein, is contained in the posterior part of the free margin of the falx cere- bri. It is of a circular form, increases in size as it passes backAvards, and termi- nates in the straight sinus. It receives several veins from the falx cerebri, and occasionally a feAV from the flat surface of the hemispheres. The Straight Sinus is situated at the line of junction of the falx cerebri with the tentorium. It is triangular in form, increases in size as it proceeds backAvards, and runs obliquely downwards and backAvards from the termination of the inferior longitudinal sinus to the torcular Herophili. Reside the inferior longitudinal sinus, it receives the venae Galeni, the inferior median cerebral veins, and the superior cerebellar. A feAV transverse bands cross its interior. The Lateral Sinuses are of large size, and situated in the attached margin of the tentorium cerebelli. They commence at the torcular Herophili, and passing horizontally outAvards to the base of the petrous portion of the temporal bone, curve downwards and inAvards on each side to reach the jugular foramen, where they terminate in the internal jugular vein. Each sinus rests, in its course, upon the inner surface of the occipital, the posterior inferior angle of the parietal, the mastoid portion of the temporal, and on the occipital again just beloAv its termina- tion. These sinuses are of unequal size, the right being the larger, and they increase in size as they proceed from behind forwards. The horizontal portion is of a tri- angular form, the curved portion semicylindrical; their inner surface is smooth, and not crossed by the fibrous bands found in the other sinuses. These sinuses receive blood from the superior longitudinal, the straight, and the occipital sinuses; and in front they communicate with the superior and inferior petrosal. They communicate with veins of the pericranium by means of the mastoid and posterior condyloid veins, and they receive the inferior cerebral and inferior cerebellar veins, and some from the diploe. The Occipital are the smallest of the cranial sinuses. They are usually two in number, and situated in the attached margin of the falx cerebelli. They commence by several small veins around the posterior margin of the foramen magnum, which communicate with the posterior spinal veins, and terminate by separate openings (sometimes by a single aperture) in the torcular Herophili. The sinuses at the base of the skull are the Cavernous. Inferior petrosal. Circular. Superior petrosal. Transverse. The Cavernous Sinuses are named from their presenting a reticulated structure. They are two in number, of large size, and placed one on each side of the sella Turcica, extending from the sphenoidal fissure to the apex of the petrous portion of the temporal bone: they receive anteriorly the ophthalmic vein through the SINUSES OF THE DURA MATER. 409 sphenoidal fissure, communicate behind Avith the petrosal sinuses, and Avith each other by the circular and transverse sinuses. On the inner Avail of each sinus is found the internal carotid artery, accompanied by filaments of the carotid plexus, and by the sixth nerve ; and on its outer Avail, the third, fourth, and ophthalmic nerves. These parts are separated from the blood floAving along the sinus-by the lining membrane, which is continuous with the inner coat of the veins. The Fig. 219.—The Sinuses at the Base of the Skull. cavity of the sinus, which is larger behind than in front, is intersected by fila- ments of fibrous tissue and small vessels. The cavernous sinuses receive the inferior anterior cerebral veins ; they communicate with the lateral sinuses by means of the superior and inferior petrosal, and with the facial vein through the ophthalmic. The Ophthalmic is a large vein, which connects the frontal at the inner angle of the orbit with the cavernous sinus ; it pursues the same course as the ophthalmic artery, and receives branches corresponding to those derived from that vessel. Forming a short single trunk, it passes through the inner extremity of the sphe- noidal fissure, and terminates in the cavernous sinus. The Circular Sinus completely surrounds the pituitary body, and communicates on each side Avith the cavernous sinuses. Its posterior half is larger than its an- terior ; and in old age it is more capacious than at an early period of life. It receives veins from the pituitary body, and from the adjacent bone and dura mater. The Inferior Petrosal Sinus is situated in the groove formed by the junction of the inferior border of the petrous portion of the temporal with the basilar process of the occipital. It commences in front at the termination of the cavernous sinus, and opens behind, at the jugular foramen, forming Avith the lateral sinus the com- mencement of the internal jugular vein. These sinuses are semicylindrical in form. The Transverse Sinus is placed transversely across the forepart of the basilar process of the occipital bone, serving to connect the two inferior petrosal 410 VEINS. Fig. 220.—The Superficial Veins of the Upper Extremity. and caA'ernous sinuses. A second is occasionally found opposite the foramen magnum. The Superior Petrosal Sinus is situated along the upper border of the petrous portion of the temporal bone, in the front part of the attached margin of the tentorium. It is small and narrow, and connects together the cavernous and lateral sinuses at each side. It receives a cerebral vein (inferior lateral cerebral) from the under part of the middle lobe, and a cerebellar vein (ante- rior lateral cerebellar) from the anterior border of the cerebellum. VEINS OF THE UPPER EXTREMITY. The veins of the upper extremity are divided into two sets: 1. The Superficial veins. 2. The deep veins. The Superficial Veins are placed imme- diately beneath the integument between the tAvo layers of superficial fascia ; they com- mence in the hand chiefly on its dorsal aspect, where they form a more or less com- plete arch. The Deep Veins accompany the arteries, and constitute the venae comites of those vessels. Both sets of vessels are provided with valves, which are more numerous in the deep than in the superficial. The superficial veins of the upper extre- mity are the Anterior ulnar. Posterior ulnar. Basilic. Radial. Cephalic. Median. Median basilic. Median cephalic. The Anterior Ulnar the anterior surface of side of the hand, and ascends along the inner side of the forearm to the bend of the elbow, where it joins with the posterior ulnar vein to form the basilic. It communicates with branches of the median vein in front, and Avith the posterior ulnar behind. The Posterior Ulnar Vein commences on the posterior surface of the ulnar side of the hand, and from the vein of the little finger (vena salvatella), situated over the fourth metacarpal space. It ascends on the poste- rior surface of the ulnar side of the fore- arm, and just below the elboAv unites with the anterior ulnar vein to form the basilic. Vein commences on the wrist and ulnar OF THE UPPER EXTREMITY. 411 The Basilic is a vein of considerable size, formed by the coalescence of the anterior and posterior ulnar veins; ascending along the inner side of the elbow, it receives the median basilic vein, and passing upwards along the inner side of the arm, pierces the deep fascia, and ascends in front of the brachial artery, termi- nating either in one of the venae comites of that vessel, or in the axillary Vein. The Radial Vein commences from the dorsal surface of the thumb, index finger, and radial side of the hand, by branches which communicate with the vena salva- tella. They form by their union a large vessel, which ascends along the radial side of the forearm, receiving numerous branches from both its surfaces. At the bend of the elboAv it receives the median cephalic, when it becomes the cephalic vein. The Cephalic Vein ascends along the outer border of the Biceps muscle, to the upper third of the arm ; it then passes in the interval betAveen the Pectoralis major and Deltoid muscles, accompanied by the descending branch of the thoracica acro- mialis artery, and terminates in the axillary vein just beloAV the clavicle. This vein is occasionally connected with the external jugular or subclavian, by a branch which passes from it upwards in front of the clavicle. The Median Vein collects the blood from the superficial structures in the palmar surface of the hand and middle line of the forearm, communicating with the an- terior ulnar and radial veins. At the bend of the elboAv, it receives a branch of communication from the deep veins, accompanying the brachial artery, and divides into two branches, the median cephalic and median basilic, which diverge from each other as they ascend. The Median Cephalic, the smaller of the two, passes outAvards in the groove betAA^een the Supinator longus and Biceps muscles, and joins with the cephalic vein. The branches of the external cutaneous nerve pass behind this vessel. The Median Basilic vein passes obliquely inAvards, in the groove betAveen the Biceps and Pronator radii teres, and joins with the basilic. This vein passes in front of the brachial artery, from which it is separated by a fibrous expansion, given off from the tendon of the Biceps to the fascia covering the Flexor muscles. Filaments of the internal cutaneous nerve pass in front as well as behind this vessel. The Deep Veins of the Upper Extremity folloAV the course of the arteries, forming their ven;e comites. They are generally tAvo in number, one lying on each side of the corresponding artery, and they are connected at intervals by short transverse branches. There are two digital veins accompanying each artery along the sides of the fingers ; these, uniting at their base, pass along the interosseous spaces in the palm, and terminate in the tAvo superficial palmar veins. Branches from these vessels on the radial side of the hand accompany the superficialis volae, and, on the ulnar side, terminate in the deep ulnar veins. The deep ulnar veins, as they pass in front of the wrist, communicate with the interosseous and superficial veins, and unite at the elboAv with the deep radial veins, to form the venae comites of the brachial artery. The Interosseous Veins accompany the anterior and posterior interosseous arteries. The anterior interosseous veins commence in front of the wrist, where they communicate with the deep radial and ulnar veins; at the upper part of the forearm they receive the posterior interosseous veins, and terminate in the venae comites of the ulnar artery. The Deep Palmar Veins accompany the deep palmar arch, being formed by branches which accompany the ramifications of this vessel. They communicate with the superficial palmar veins at the inner side of the hand ; and on the outer side, terminate in the venae comites of the radial artery. At the Avrist, they receive a dorsal and a palmar branch from the thumb, and unite with the deep radial veins. Accompanying the radial artery, these vessels terminate in the venie comites of the brachial artery. The Brachial Veins are placed one on each side of the brachial artery, receiving 412 VEINS. branches corresponding Avith those given off from this vessel; at the lower margin of the axilla they unite Avith the basilic to form the axillary vein. The deep veins have numerous anastomoses, not only Avith each other, but also with the superficial veins. Axillary Vein. The axillary vein is of large size and formed by the continuation upAvards of the basilic vein. It commences at the loAver part of the axillary space, and increasing in size as it ascends, by receiving branches corresponding with those of the axillary artery, terminates immediately beneath the clavicle at the outer mar- gin of the first rib, and becomes the subclavian vein. This vessel is covered in front by the Pectoral muscles and costo-coracoid membrane, and lies on the tho- racic side of. the axillary artery. Opposite the Subscapularis, it is joined by a large vein, formed by the junction of the venae comites of the brachial; and near its termination it receives the cephalic vein. This vein is provided with valves at the point where it is joined by the cephalic and basilic veins. Subclavian Vein. The subclavian vein, the continuation of the axillary, extends from the outer margin of the first rib to the inner end of the sterno-clavicular articulation, where it unites Avith the internal jugular, to form the vena innominata. It is in relation, in front, with the clavicle and Subclavius muscle; behind, with the subclavian artery, from AA'hich it is separated internally by the Scalenus anticus and phrenic nerve. Below, it rests in a depression on the first rib and upon the pleura. Above, it is covered by the cervical fascia and integument. The subclavian vein occasionally rises in the neck to a level with the third part of the subclavian artery, and in two instances, has been seen passing with this vessel behind the Scalenus anticus. This Aressel is provided Avith valves near its termination in the innominate. Branches. It receives the external and anterior jugular veins and a small branch from the cephalic, outside the Scalenus; and on the inner side of this muscle, the vertebral and internal jugular veins. The Vertebral Vein commences by numerous small branches in the occipital region, from the deep muscles at the upper and back part of the neck, passes out- Avards, and enters the foramen in the transverse process of the atlas, and descends by the side of the vertebral artery, in the canal formed by the transverse processes of the cervical vertebrae. Emerging from the foramen in the transverse process of the sixth cervical, it terminates at the root of the neck in the subclavian vein near its junction with the vena innominata. This vein, in the loAver part of its course, occasionally divides into two branches ; one emerges with the artery at the sixth cervical vertebra, the other escapes through the foramen in the seventh cervical. Branches. This vein receives in its course the posterior condyloid vein, muscular branches from the muscles in the prevertebral region; dorsi-spinal veins, from the back part of the cervical portion of the spine; meningo-rachidian veins, from the interior of the spinal canal; and lastly, the ascending and deep cervical Areins. Innominate Veins. The venae innominatae (Fig. 221) are two large trunks, placed one on each side of the root of the neck, and formed by the union of the internal jugular and subcla- vian veins of the corresponding side. The Right Vena Innominata is a short vessel, about an inch and a half in length, which commences at the inner end of the clavicle, and passing almost vertically downwards, joins with the left vena innominata just below the cartilage of the first rib, to form the superior vena cava. It lies superficial and external to the arteria innominata ; on its right side the pleura is interposed between it and the apex of the lung. This vein at its angle of junction Avith the subclavian, receives the right INNOMINATE. 413 221.—The Vence Cavre and Azygos Veins, wkh their Formative Branches. nterior Jugular Su-periov Thyroid: Mddle Thy k -External Jvt/ular lymphatic duct; and lower down, the right internal mammary, right inferior thvroid, and right superior intercostal veins. The Left Vena Innomi- nata, about three inches in length, and larger than the right, passes obliquely from left to right across the up- per and front part of the chest, to unite with its fel- low of the opposite side, forming the superior vena cava. It is in relation in front with the sternal end of the left clavicle, the left sterno-clavicular articula- tion, and Avith the first piece of the sternum, from which it is separated by the Sterno-hyoid and Sterno- thyroid muscles, the thy- mus gland, or its remains, and some loose areolar tis- sue. Behind, it lies across the roots of the three large arteries arising from the arch of the aorta. This vessel, at its commence- ment, receiAres the thoracic duct; it is joined also by the left inferior thyroid, left internal mammary, and the left superior intercostal veins, and occasionally some thymic and pericardiac veins. There are no valves in the venae innominatae. Peculiarities. Sometimes the innominate veins open sepa- rately into the right auricle; in such cases the right vein takes the ordinary course of the superior vena cava, but the left vein, after communicating by a small branch with the right one, passes in front of the root of the left lung, and turning to the back of the heart, receives the cardiac veins, and terminates in the back of the right auricle. This occasional condition of the veins in the adult is a regular one in the foetus at an early period, and the two vessels are persis- tent in birds and some mam- malia. The subsequent changes which take place in these ves- 414 VEINS. sels are the following. The communicating branch between the two trunks enlarges and forms the future left innominate vein; the remaining part of the left trunk is obliterated as far as the heart, where it remains pervious, and forms the coronary sinus; a remnant of the obliterated vessel is seen in adult life as a fibrous band passing along the back of the left auricle and in front of the root of the left lung, called, by Mr. Marshall, the vestigial fold of the pericardium. The Internal Mammary Veins, tAvo in number to each artery, folloAV the course of that vessel, and receive branches corresponding with those derived from it. The two veins unite into a single trunk, Avhich terminates in the innominate vein. The Inferior Thyroid Veins, two, frequently three or four in number, arise in the venous plexus on the thyroid body, communicating with the middle and supe- rior thyroid veins. The left one descends in front of the trachea, behind the Sterno-thyroid muscles, communicating with its fellow by transverse branches and terminates in the left vena innominata. The right one, Avhich is placed a little to the right of the median line, opens into the right vena innominata, just at its junction with the superior cava. These veins receive tracheal and inferior laryn- geal branches, and are provided with valves at their termination in the innominate Areins. The Superior Intercostal Veins return the blood from the upper intercostal spaces. The right superior intercostal, much smaller than the left, closely corresponds with the superior intercostal artery, receiving the blood from the first, or first and second intercostal spaces, and terminates in the right vena innominata. Some- times it passes down, and opens into the vena azygos major. The left superior intercostal is ahvays larger than the right, but varies in size in different subjects, being small Avhen the left upper azygos vein is large, and vice versd. It is usually formed by branches from the tAvo or three upper intercostal spaces, and, passing across the avch of the aorta, terminates in the left vena innominata. The left bronchial vein opens into it. Superior Vena Cava. The Superior Vena Cava receives the blood which is conveyed to the heart from the whole of the upper half of the body. It is a short trunk, varying from two inches and a half to three inches in length, formed by the junction of the two venae innominate. It commences immediately beloAv the cartilage of the first rib on the right side, and, descending vertically downwards, enters the pericardium, and ter- minates in the upper part of the right auricle. In its course, it describes a slight curve, the convexity of which is turned to the right side. Relations. The part external to the pericardium is in relation, in front, with the thoracic fascia, which separates it from the thymus gland, and from the sternum; behind, with the trachea, from which it is separated by numerous lymphatic glands. On its right side, with the right phrenic nerve and the right lung; on its left side, with the arch of the aorta. The portion contained within the pericardium is covered by the serous layer of that membrane, in its anterior three-fourths. It is in relation, behind, with the right pulmonary artery, and right superior pul- monary veins; on the left side, with the aorta. It receives the vena azygos major, just before it enters the pericardium, and several small veins from the mediastinum and pericardium. The superior vena cava has no valves. Azygos Veins. The Azygos Veins connect together the superior and inferior venae cavae, supplying the place of these vessels in that part of the trunk in which they are deficient, on account of their connection with the heart. The larger, or Right Azygos Vein, commences opposite the first or second lumbar vertebra, by receiving a branch from the right lumbar veins; sometimes by a branch from the renal vein, or from the inferior vena cava. It enters the AZYGOS; SPINAR 415 thorax through the aortic opening in the Diaphragm, and passes along the right side of the vertebral column to the third dorsal vertebra, where it arches forward, over the root of the right lung, and terminates in the superior vena cava, just before that vessel enters the pericardium. Whilst passing through the aortic opening of the Diaphragm, it lies Avith the thoracic duct on the right side of the aorta ; and in the thorax it lies upon the intercostal arteries, on the right side of the aorta and thoracic duct, and covered by the pleura. Branches. It receives nine or ten lower intercostal veins of the right side, the vena azygos minor, several oesophageal, mediastinal, and vertebral veins; near its termination, the right bronchial vein; and it is occasionally connected with the right superior intercostal vein. A feAV imperfect valves are found in this vein, but its branches are provided with complete valves. The intercostal veins on the left side, below the two or three upper intercostal spaces, usually form tAvo trunks, named the left lower, and the left upper azygos veins. The Left Lower or Smaller Azygos Vein, commences in the lumbar region, by a branch from one of the lumbar veins, or from the left renal. It passes into the thorax, through the left crus of the Diaphragm, and, ascending on the left side of the spine, as high as the sixth or seventh vertebra, passes across the column, behind the aorta and thoracic duct, to terminate in the right azygos vein. It receives the four or five lower intercostal veins of the left side, and some oesophageal and medi- astinal veins. The Left Upper Azygos varies according to the size of the left superior inter- costal. It receives veins from the intercostal spaces betAveen the superior inter- costal vein, and highest branch of the left loAver azygos. They are usually two or three in number, and join to form a trunk which ends in the right azygos vein, or in the left lower azygos. When this vein is small, or altogether wanting, the left superior intercostal vein will extend as Ioav as the fifth or sixth intercostal space. The Bronchial Veins return the blood from the substance of the lungs; that of the right side opens into the vena azygos major, near its termination ; that of the left side, in the left superior intercostal vein. The Spinal Veins. The numerous venous plexuses placed upon and within the spine, may be arranged into four sets. 1. Those placed on the exterior of the spinal column, the dorsi-spinal veins. 2. Those situated in the interior of the spinal canal, betAveen the vertebrae and the theca vertebralis, meningo-rachidian veins. 3. The veins of the bodies of the vertebrae. 4. The veins of the spinal cord, medulli spinal. 1. The Dorsi-spinal Veins commence by small branches, Avhich receive their blood from the integument of the back of the spine, and from the muscles in the vertebral grooves. They form a complicated netAvork, Avhich surrounds the spinous processes, laminae, and the transverse and articular processes of all the vertebra?. At the bases of the transverse processes, they communicate, by means of ascend- ing and descending branches, with the veins surrounding the contiguous vertebrae, and Avith the veins in the interior of the spine, in the intervals between the arches of the vertebrse, perforating the ligamenta subflava, and terminate in the vertebral vein in the neck, in the intercostal veins in the thorax, in the lumbar and sacral veins in the loins and pelvis. 2. The veins contained in the interior of the spinal canal are situated between the theca vertebralis and the vertebrae. They consist of tAvo longitudinal plexuses, one of which runs along the posterior surface of the bodies of the vertebrae, throughout the entire length of the spinal canal (anterior longitudinal 416 VEINS. spinal veins), receiving the veins belonging to the bodies of the vertebrae (vena1 basis vertebrarum). The other plexus is placed on the inner, or anterior surface, of the laminae of the vertebrse Fig. 222,-Transverse Section of a Dorsal Vertebra, rp, j d , showing the Spinal A ems. .J ""& LU^ entire length of the spinal canal, and are called the posterior longitudinal spinal veins. The Anterior Longitudinal Spinal Veins consist of two large, tortuous venous canals, which extend along the whole length of the vertebral co- lumn, from the foramen mag- num to the base of the coccyx, being placed one on each side of the posterior surface of the bodies of the vertebrae, exter- nal to the posterior common ligament. These veins com- municate together opposite each vertebra, by transverse trunks Avhich pass beneath large venae basis vertebrarum, from the interior The anterior longitudinal spinal veins are least sacral regions. They are not of uniform size being alternately enlarged and constricted. At the intervertebral foramina they communicate the ligament, and receive the of the body of each vertebra. developed in the cervical and throughout 223.—Vertical Section of two Dorsal Vertebrse, showing the Spinal Veins. Avith the dorsi-spinal veins, and with the vertebral vein in the neck, with the intercostal veins in the dorsal region, and with the lumbar and sa- cral veins in the corresponding regions. The Posterior Longitudi- nal Spinal Veins, smaller than the anterior, are situated one on either side, between the inner surface of the la- minae and the theca vertebra- lis. They communicate (like the anterior), opposite each vertebra,by transverse trunks; and with the anterior longitudinal veins, by lateral transverse branches, which pass from behind forAvards. These veins, at the intervertebral foramina, join with the dorsi-spinal veins. 3. The Veins of the Bodies of the Vertebra? (venae basis vertebrarum) emerge from the foramina on their posterior surface, and join the transverse trunk con- necting the anterior longitudinal spinal veins. They are contained in large, tor- tuous channels in the substance of the bones, similar in every respect to those found in the diploe of the cranial bones. These canals lie parallel to the upper and loAver surface of the bones, arise from the entire circumference of the vertebra, communicate with veins which enter through the foramina on the anterior surface of the bodies, and converge to the principal canal, which is sometimes double towards its posterior part. They become greatly developed in advanced age. 4. The Veins of the Spinal Cord (medulli-spinal) consist of a minute tortuous OF THE LOWER EXTREMITY. 41' venous plexus, which covers the entire surface of the cord, being situated between the pia mater and arachnoid. These vessels emerge chiefly from the posterior median furrow, and are largest in the lumbar region. Near the base of the skull they unite, and form two or three small trunks, which communicate with the vertebral veins, and then terminate in the inferior cerebellar veins, or in the petrosal sinuses. Each of the spinal nerves is accompanied by a branch as far as the intervertebral foramina, where they join the other veins from the spinal canal. There are no valves in the spinal veins. / ^\,\^ Fig. 224. The Internal or Long Sr phenous Vein and its Branches. VEINS OF THE LOWER EXTREMITY. The veins of the lower extremity are divided, like those of the upper, into tAvo sets, superficial and deep : the superficial veins being placed be- neath the integument, betAveen the two layers of superficial fascia ; the deep veins accompanying the arteries, and forming the venae comites of those A'essels. Both sets of veins are provided with valves, which are more numerous in the deep than in the superficial set. These valves are also more numerous in the lower than in the upper limbs. The Superficial Veins of the lower extremity are the internal or long saphenous, and the ex- ternal or short saphenous. The Internal Saphenous Vein (Fig. 224) com- mences from a minute plexus, Avhich covers the dorsum and inner side of the foot; it ascends in front of the inner ankle, and along the inner side of the leg, behind the inner margin of the tibia, accompanied by the internal saphenous nerve. At the knee it passes backAvards behind the inner condyle of the femur, ascends along the inside of the thigh, and, passing through the saphenous opening in the fascia lata, terminates in the femo- ra] vein, an inch and a half below Poupart's liga- ment. This vein receives in its course cutaneous branches from the leg and thigh, and at the saphe- nous opening, the superficial epigastric, superficial circumflex iliac, and external pudic veins. The veins from the inner and back part of the thigh frequently unite to form a large vessel, which enters the main trunk near the saphenous opening, and sometimes those on the outer side of the thigh join to form a large branch; so that occasionally three large veins are seen converging from different parts of the thigh towards the saphenous opening. The internal saphena communicates in the foot with the internal plantar vein ; in the leg, Avith the posterior'tibial veins, by branches Avhich perforate the tibial origin of the Soleus muscle, and also with the anterior tibial veins ; at the knee, with the articular veins; in the thigh. Avith the femoral vein by one or more branches. The valves in this 29 ^S ,\ J' W m 118 VEINS. Fig. 225.—External or Short Saphe- nous Vein. vein vary from tAvo to six in number; they are more numerous in the thigh than in the leg. The External or Short Saphenous Vein is formed by branches which collect the blood from the dorsum and outer side of the foot; it passes behind the outer ankle, and along the outer border of the tendo Achillis, across Avhich it passes at an acute angle to reach the middle line of the posterior aspect of the leg. Ascend- ing directly upAvards, it perforates the deep fascia in the loAver part of the popliteal space, and ter- minates in the popliteal vein, betAveen the heads of the Gastrocnemius muscle. It is accompanied by the external saphenous nerve. It receives nu- merous large branches from the back part of the leg, and communicates with the deep veins on the dorsum of the foot, and behind the outer malleolus. This vein has only tAvo valves, one of which is ahvays found near its termination in the popliteal vein. The Deep Veins of the lower extremity accom- pany the arteries and their branches, and are called the vence comites of those vessels. The external and internal plantar veins unite to form the posterior tibial. They accompany the posterior tibial artery, and are joined by the pero- neal veins. The Anterior Tibial Veins are formed by a continuation upwards of the venae dorsales pedis. They perforate the interosseous membrane at the upper part of the leg, and form, by their junction Avith the posterior, tibial, the popliteal vein. The valves in the deep veins are very nu- merous. Popliteal Vein. The popliteal vein is formed by the junction of the venae comites of the anterior and posterior tibial vessels ; it ascends through the popliteal space to the tendinous aperture in the Adductor magnus, where it becomes the femoral vein. In the lower part of its course it is placed internal to the artery ; between the heads of the Gastroc- nemius it is superficial to that vessel, but above the knee joint it is close to its outer side. It receives the sural veins from the Gastrocnemius muscle, the articular veins, and the external saphenous. The valves in this vein are usually four in number. Femoral Vein. The femoral vein accompanies the femoral artery through the upper two-thirds of the thigh. In the loAver part of its course it lies external to the artery; higher up it is behind it; and beneath Poupart's ligament it lies to its inner side, and on the same plane as that vessel. It receives numerous muscular branches; the pro- funda femoris joins it about an inch and a half below Poupart's ligament, and near its termination the internal saphenous vein. The valves in this vein are four or five in number. ILIAC. 419 External Iliac Vein. The external iliac vein commences at the termination of the femoral, beneath the crural arch, and passing upwards along the brim of the pelvis, terminates opposite the sacro-iliac symphysis, by uniting with the internal iliac to form the common iliac vein. On the right side, it lies at first along the inner side of the external iliac artery ; but as it passes upAvards, gradually inclines behind it. On the left side, it lies altogether on the inner side of the artery. It receives, imme- diately above Poupart's ligament, the epigastric and circumflex iliac veins. It has no valves. Internal Iliac Vein. The internal iliac vein is formed by the venae comites of the branches of the internal iliac artery, the umbilical arteries excepted. It receives the blood from the exterior of the pelvis by the gluteal, sciatic, internal pudic, and obturator veins; and from the organs in the cavity of the pelvis by the hemorrhoidal and vesico-prostatic plexuses in the male, and the uterine and vaginal plexuses in the female. The vessels forming these plexuses are remarkable for their large size, their frequent anastomoses, and the number of valves which they contain. The internal iliac vein lies at first on the inner side, and then behind the internal iliac artery, and terminates opposite the sacro-iliac articulation, by uniting with the external iliac, to form the common iliac vein. This vessel has no valves. The Hemorrhoidal Plexus surrounds the loAver end of the rectum, being formed by the superior hemorrhoidal veins, branches of the inferior mesenteric, and the middle and inferior hemorrhoidal, Avhich terminate in the internal iliac. The portal and general venous systems have a free communication by means of the branches composing this plexus. The Vesico-prostatic Plexus surrounds the neck and base of the bladder and prostate gland. It communicates Avith the hemorrhoidal plexus behind, and re- ceives the great dorsal vein of the penis, Avhich enters the pelvis beneath the subpubic ligament. This plexus is supported upon the sides of the bladder by a reflection of the pelvic fascia. These veins are very liable to become varicose, and often contain hard earthy concretions, called phlebolitcs. The Dorsal Vein of the Penis is a vessel of large size, which returns the blood from the body of this organ. At first it consists of tAvo branches, Avhich are con- tained in the groove on the dorsum of the penis, and receives veins from the glans, the corpus spongiosum, and numerous superficial veins ; these unite near the loot of the penis into a single trunk, which pierces the triangular ligament beneath the pubic arch, and divides into two branches, which enter the prostatic plexus. The Vaginal Plexus surrounds the mucous membrane of the vagina, being especially developed at the orifice of this canal; it communicates A\lth the vesical plexus in front, and Avith the hemorrhoidal plexus behind. The Uterine Plexus is situated along the sides and superior angles of the uterus, receiving large venous canals (the uterine sinuses) from its substance. The veins composing this plexus anastomose frequently Avith each other, and some of them communicate with the ovarian veins. They are not tortuous like the arteries. Common Iliac Vein. Each common iliac vein is formed by the union of the external and internal iliac veins in front of the sacro-vertebral articulation ; passing obliquely upAvards towards the right side, they terminate upon the intervertebral substance between the fourth and fifth lumbar vertebrae, where they unite at an acute angle to form the inferior vena cava. The right common iliac is shorter than the left, nearly vertical in its direction, and ascends behind and then to* the outer side of its cor- responding artery. The left common iliac, longer and more oblique in its course, is at first situated at the inner side of the corresponding artery, and then behind the right common iliac. Each common iliac receives the ilio-lumbar, and some- 420 VEINS. times the lateral sacral veins. The left one receives, in addition, the middle sacral vein. No valves are found in these veins. The Middle Sacral Vein accompanies its corresponding artery along the front of the sacrum, and terminates in the left common iliac vein ; occasionally in the commencement of the inferior vena cava. Peculiarities. The left common iliac vein, instead of joining with the right one in its usual position, occasionally ascends on the left side of the aorta as high as the kidney, where, after receiving the left renal vein, it crosses over the aorta, and then joins with the right vein to form the vena cava. In these cases, the tAvo common iliacs are connected by a small communicating branch at the spot where they are usually united. Inferior Vena Cava. The inferior vena cava returns to the heart the blood from all the parts below the Diaphragm. It is formed by the junction of the tAvo common iliac veins on the riodit side of the intervertebral substance between the fourth and fifth lumbar vertebrae. It passes upAvards along the front of the spine, on the right side of the aorta, and having reached the under surface of the liver, is contained in a groove in its posterior border. It then perforates the tendinous centre of the Diaphragm, enters the pericardium, Avhere it is covered by its serous layer, and terminates in the lower and back part of the right auricle. At its termination in the auricle, it is provided Avith a valve, the Eustachian, Avhich is of large size during fcetal life. Relations. In front, from below upAvards, with the mesentery, transArerse por- tion of the duodenum, the pancreas, portal vein and the posterior border of the liver, which partly and occasionally completely surrounds it; behind, it rests upon the vertebral column, the right crus of the Diaphragm, the right renal and lumbar arteries; on the left side, it is in relation Avith the aorta. It receives in its course the following branches :— Lumbar. Suprarenal. Right spermatic. Phrenic. Renal. Hepatic. Peculiarities. In Position. This vessel is sometimes placed on the left side of the aorta, as high as the left renal vein, after receiving which, it crosses over to its usual position on the right side; or may be placed altogether on the left side of the aorta, as far upwards as its termination in the heart; in such cases, the abdominal and thoracic viscera, together with the great vessels, are all transposed. Point of Termination. Occasionally the inferior vena cava joins the right azygos vein, which is then of large size. In such cases, the superior caATa receives the whole of the blood from the body before transmitting it to the right auricle, the blood from the hepatic veins excepted, these vessels terminating directly in the right auricle. The Lumbar Veins, three or four in number on each side, collect the blood by dorsal branches from the muscles and integument of the loins, and by abdominal branches from the Avails of the abdomen, Avhere they communicate with the epigastric veins. At the spine, they receive branches from the spinal plexuses, and then pass forAvards round the sides of the bodies of the vertebrae beneath the Psoas magnus, and terminate at the back part of the inferior cava. The left lumbar veins are longer than the right, and pass behind the aorta. The lumbar veins communicate with each other by branches which pass in front of the transverse processes. Occasionally two or more of these veins unite to form a single trunk, the ascending lumbar, Avhich serves to connect the common iliac, ilio-lujnbar, lumbar, and azygos veins of the corresponding side of the bodv. The Spermatic Veins emerge from the back of the testis, and receive branches from the epididymis; they form a branched and convoluted plexus, called the spermatic plexus (plexus* pampiniformis), below the abdominal ring: the vessels composing this plexus are very numerous, and ascend along the cord in front of the vas deferens; having entered the abdomen, they coalesce to form two branches, which ascend on the Psoas muscle, behind the peritoneum, lying one on each INFERIOR CAVA; PORTAL SYSTEM. 421 side of the spermatic artery, and to unite to form a single vessel, which opens on the right side in the inferior vena cava, piercing this vessel obliquely ; on the left side in the left renal vein, terminating at right angles Avith this vein. The sper- matic veins are provided with valves. The left spermatic vein passes behind the sigmoid flexure of the colon ; this circumstance, as Avell as the indirect communi- cation of the vessel Avith the vena cava, may serve to explain the more frequent occurrence of varicocele on the left side. The Ovarian Veins are analogous to the spermatic in the male ; they form a plexus near the ovary, and in the broad ligament and Fallopian tube, communi- cating with the uterine plexus. They terminate as in the male. Valves are occasionally found in these veins. These vessels, like the uterine veins, become much enlarged during pregnancy. The Renal Veins are of large size, and placed in front of the divisions of the renal arteries. The left is longer than the right and passes in front of the aorta, just beloAV the origin of the superior mesenteric artery. It receives the left spermatic vein. It usually opens into the vena caAra, a little higher than the right. The Suprarenal Vein terminates, on the right side, in the vena cava ; on the left side, in the left renal or phrenic vein. The Phrenic Veins folloAV the course of the phrenic arteries. The two supe- rior, of small size, accompany the corresponding nerve and artery ; the right terminating opposite the junction of the two venae innominatae, the left in the left superior intercostal or left internal mammary. The two inferior phrenic veins follow the course of the inferior phrenic arteries, and terminate, the right in the inferior vena cava, the left in the left renal vein. The Hepatic Veins commence in the substance of the liver, in the capillary terminations of the vena portae : these branches, gradually uniting, form three large veins, which converge towards the posterior border of the liver, and open into the inferior vena cava-, whilst that vessel is situated in the groove at the back part of this organ. Of these three veins, one from the right, and another from the left lobe, open obliquely into the vena cava ; that from the middle of the organ and lobus Spigelii having a straight course. The hepatic veins run singly, and are in direct contact with the hepatic tissue. They are destitute of valves. Portal System of Veins. The portal venous system is composed of four large veins, which collect the venous blood from the viscera of digestion. The trunk formed by their union (vena portae) enters the liver, ramifies throughout its substance, and its branches again emerging from that organ as the hepatic veins, terminate in the inferior vena cava. The branches of this vein are in all cases single, and destitute of valves. The veins forming the portal system are the Inferior mesenteric. Splenic. Superior mesenteric. Gastric. The Inferior Mesenteric Vein returns the blood from the rectum, sigmoid flexure, and descending colon, corresponding Avith the ramifications of the branches of the inferior mesenteric artery. Ascending beneath the peritoneum in the lumbar region, it passes behind the transverse portion of the duodenum and pan- creas, and terminates in the splenic vein. Its hemorrhoidal branches inosculate with those of the internal iliac, and thus establish a communication betAveen the portal and the general venous system. The Superior Mesenteric Vein returns the blood from the small intestines, and from the cajcum and ascending and transverse portions of the colon, corresponding with the distribution of the branches of the superior mesenteric artery. The large trunk formed by the union of these branches ascends along the right side and in front of the corresponding artery, passes in front of the transverse portion of 422 VEINS. the duodenum, and unites behind the upper border of the pancreas Avith the splenic vein, to form the vena porta\ The Splenic Vein commences by five or six large branches, which return the blood from the substance of the spleen. These uniting form a single vessel, which passes from left to right behind the upper border of the pancreas, and ter- minate at its greater end by uniting at a right angle Avith the superior mesenteric Fig. 226.—Portal Vein and its Branches. to form the vena portae. The splenic vein is of large size, and not tortuous like the artery. It receives the vasa brevia from the left extremity of the stomach, the left gastro-epiploic vein, pancreatic branches from the pancreas, the pan- creatico-duodenai vein, and the inferior mesenteric vein. The Gastric is a vein of small size, which accompanies the gastric artery from left to right along the lesser curvature of the stomach, and terminates in the vena portae. PORTAL; CARDIAC. 423 The Portal Vein is formed by the junction of the superior mesenteric and splenic veins, their union taking place in front of the vena cava, and behind the upper border of the great end of the pancreas. Passing upAvards through the right border of the lesser omentum to the under surface of the liver, it enters the trans- verse fissure, where it is someAvhat enlarged, forming the sinus of the portal vein, and divides into tAvo branches, Avhich accompany the ramifications of the hepatic artery and hepatic duct throughout its substance. Of these tAvo branches, the right is the larger, but the shorter of the tAvo. The portal vein is about four inches in length, and, whilst contained in the lesser omentum, lies behind and betAveen the hepatic duct and artery, the former being to the right, the latter to the left. These structures are accompanied by filaments of the hepatic plexus and numerous lymphatics, surrounded by a quantity of loose areolar tissue, the capsule of Glisson, and placed betAveen the layers of the lesser omentum. The vena portal receives the gastric and cystic veins ; the latter vein sometimes terminates in the right branch of the vena porta}. Within the liver, the portal vein receives the blood from the branches of the hepatic artery. Cardiac Veins. The veins which return the blood from the substance of the heart arc, the Great cardiac vein. Anterior cardiac veins. Posterior cardiac vein. Venae Thebesii. The Great Coronary or Cardiac Vein is a vessel of considerable size, Avhich commences at the apex of the heart, and ascends along the anterior ventricular groove to the base of the ventricles. It then curves to the left side, around the auriculo-ventricular groove, betAveen the left auricle and ventricle, to the back part of the heart, and opens into the coronary sinus, its aperture being guarded by two valves. It receives the posterior cardiac Arein, and the left cardiac veins from the left auricle and ventricle, one of Avhich, ascending along the left margin of the ventricle, is of large size. The branches joining it are provided with valves. The Posterior Cardiac Vein commences, by small branches, at the apex of the heart, communicating Avith those of the preceding. It ascends along the groove betAveen the ventricles, on the posterior surface of the heart, to its base, and ter- minates in the coronary sinus, its orifice being guarded by a valve. It receives the veins from the posterior surface of both ventricles. The Anterior Cardiac Veins are three or four small branches, Avhich collect the blood from the anterior surface of the right ventricle. One of these, larger than the rest, runs along the right border of the heart, the vein of Galen. They open separately into the lower part of the right auricle. The Vence Thebesii are numerous minute veins, Avhich return the blood directly from the muscular substance, Avithout entering the venous current. They open, by minute orifices (foramina Thebesii), on the inner surface of the right auricle. The Coronary Sinus is that portion of the coronary vein which is situated in the posterior part of the left auriculo-ventricular groove. It is about an inch in length, presents a considerable dilatation, and is covered by the muscular fibres of the left auricle. It receives the great cardiac vein, the posterior cardiac vein, and an oblique vein from the back part of the left auricle, the remnant of the obliterated left innominate trunk of the foetus, described by Mr. Marshall. The coronary sinus terminates in the right auricle, betAveen the inferior vena cava and the auriculo- ventricular aperture, its orifice being guarded by a semilunar fold of the lining membrane of the heart, the coronary valve. All the branches joining this vessel. excepting the oblique vein aboAre-mentioned, are provided with valves. 124 VEINS. The Pulmonary Veins. The Pulmonary Veins return the arterial blood from the lungs to the left auricle of the heart. They are four in number, two for each lung. The pulmonary differ from other veins in several respects. 1. They carry arterial, instead of venous blood. 2. They are destitute of valves. 3. They are only slightly larger than the arteries they accompany. 4. And they accompany those vessels singly. They commence in a capillary network, upon the parietes of the bronchial cells, Avhere they are continuous Avith the ramifications of the pulmonary artery, and, uniting together, form a single trunk for each lobule. These branches, successively unit- ing, form a single trunk for each lobe, three for the right, and two for the left lung. The vein of the middle lobe of the right lung unites with that from the upper lobe, in most cases, forming tAvo trunks on each side, which open separately into the left auricle. Occasionally they remain separate; there are then three veins on the right side. Not unfrequently, the tAvo left pulmonary veins terminate by a common opening. Within the lung, the branches of the pulmonary artery are in front, the veins behind, and the bronchi betAveen the two. At the root of the lung, the veins are in front, the artery in the middle, and the bronchus behind. Within the pericardium, their anterior surface is invested by the serous layer of this membrane, the right pulmonary veins pass behind the right auricle and as- cending aorta; the left pass in front of the thoracic aorta, with the left pulmonary artery. Of the Lymphatics. T^ITE Lymphatics have derived their name from the appearance of the fluid con- -*- tained in their interior (lympha, " water"). They are also called absorbents, from the property these vessels possess of absorbing foreign matters into the system, and carrying them into the circulation. The lymphatic system includes not only the lymphatic A^essels and the glands through Avhich they pass, but also the lacteal or chyliferous vessels. The lacteals are the lymphatic vessels of the small intestine, and differ in no respect from the lymphatics generally, excepting that they carry a milk-white fluid, the chyle, during the process of digestion, and convey it into the blood through the thoracic duct. The lymphatics are exceedingly delicate vessels, the coats of which are so transparent, that the fluid they contain is readily seen through them. They retain a nearly uniform size, being interrupted at interA'als by constrictions, which give to them a knotted or beaded appearance, owing to the presence of valves in their interior. They are found in nearly every texture and organ of the body, with the exception of the substance of the brain and spinal cord, the eyeball, cartilage, tendon, membranes of the ovum, the placenta, and umbilical cord. Their existence in the substance of bone is doubtful. The lymphatics are arranged into a superficial and deep set. The superficial vessels, on the surface of the body, are placed immediately beneath the integu- ment, accompanying the superficial veins; they join the deep lymphatics in certain situations by perforating the deep fascia. In the interior of the body, they lie in the submucous areolar tissue, throughout the Avhole length of the gastro-pulmonary and genito-urinary tracts; or in the subserous areolar tissue, beneath the serous membrane covering the various organs in the cranial, thoracic, and abdominal cavities. In each of these situations these vessels arise in the form of a dense plexiform network, consisting of several strata; the vessels com- posing Avhich, as Avell as the meshes betAveen them, are much larger than the capillary plexus. From these netAvorks small vessels emerge, wliich pass, either to a neighboring gland, or to join some larger lymphatic trunk. The deep lymphatics, fewer in number, and larger than the superficial, accompany the deep bloodvessels. Their mode of origin is not known; it is, however, probable, that it is similar to that of the superficial A^essels. The lymphatics of any part or organ exceed, in number, the veins; but in size they are much smaller. Their anastomoses, also, especially of the large trunks, are more frequent, and are effected by vessels equal in diameter to those which they connect, the continuous trunks retaining the same diameter. The lymphatic vessels, like arteries and veins, are composed of three coats, internal, middle, and external. . The internal is an epithelial and elastic coat. It is thin, transparent, slightly elastic, and ruptures sooner than the other coats. It is composed of a layer of scaly epithelium, supported on one or more laminae of longitudinal elastic fibres. The middle, or muscular coat, is thin, extensile, and elastic, consisting inter- nally of a layer of longitudinal muscular fibres of the involuntary kind, inter- mixed Avith some areolar tissue, external to wliich, in the larger lymphatics, is a layer of circular fibres. The external, or areolo-fibrous coat, is similar to that of the bloodvessels. It is thin, but very extensile and elastic, composed of filaments of areolar tissue, inter- mixed with some muscular fibres, longitudinally or obliquely disposed. It forms a 12G LYMPHATICS. protective covering to the other coats, and serves to connect the vessels with the neighboring structures. The lymphatics are supplied by nutrient vessels, Avhich are distributed to their outer and middle coats; but no nerves have at present been traced into them. The lymphatics are very generally provided Avith valves, Avhich assist very materially in effecting the circulation of the fluid they contain. They are formed of a thin layer of fibrous tissue, coated on both surfaces with scaly epithelium. Their form is semilunar; they are attached by their convex edge to the sides of the vessel, the concave edge being free, and directed in the course of the contained current. Most usually, tAvo such valves, of equal size, are found placed opposite one another; but occasionally exceptions occur, especially at or near the anasto- moses of lymphatic vessels. Thus one valve may be of very rudimentary size, the other increased in proportion. In other cases, the semilunar flaps have been found directed transversely across the vessel, instead of obliquely, so as to impede the circulation in both directions, but not to completely arrest it in either; or the semilunar flaps, taking the same direction, have been united on one side, so that they formed, by their union, a transverse septum, having a partial transverse slit; and sometimes the flap Avas constituted of a circular fold, attached*to the entire circumference of the vessel, and haAlng in its centre a circular or elliptical aper- ture, the arrangements of the flaps being similar to those composing the ileo- caecal valve. The valves in the lymphatic vessels are placed at much shorter intervals than in the veins. They are most numerous near the lymphatic glands, and they are found more frequently in the lymphatics of the neck and upper extremity, than in the lower. The wall of the lymphatics, immediately above the point of attachment of each segment of a valve, is expanded into a pouch or sinus, which gives to these vessels, when distended, the knotted or beaded appearance Avhich they pre- sent. Valves are wanting in the vessels composing the plexiform network in Avhich the lymphatics originate. There is no satisfactory eAudence to prove that any natural communication exists between the lymphatics of glandular organs and their ducts, or betAveen the lymphatics and the capillary vessels. The lymphatics or absorbent glands, named also conglobate glands, are small solid glandular bodies, situated in the course of the lymphatic and lacteal A^essels. They are found in the neck and on the external parts of the head; in the upper extremity, in the axilla and front of the elboAv ; in the lower extremity, in the groin and popliteal space. In the abdomen, they are found in large numbers in the mesentery, and along the side of the aorta, vena cava, and iliac vessels; and in the thorax, in the anterior and posterior mediastina. They are somewhat flattened, and of a round or oval form. In size, they vary from a hemp-seed to an almond, and their color, on section, is of a pinkish-gray tint, excepting the bronchial glands, which in the adult are mottled with black. The lymphatic and lacteal vessels pass through these bodies in their passage to the thoracic and lymphatic ducts. A lymphatic or lacteal, previous to entering a gland, divides into several small branches, which are named infevent or afferent vessels (vasa inferentia or afferentia); and those which emerge from it are called efferent vessels (vasa efferentia). In structure they are composed of a superficial or cortical spongy substance, about two or three lines in thickness, containing numerous small cavities or loculi, filled with a whitish pulpy matter; the afferent vessels pour their contents into these loculi, which communicate by minute vessels with the lymphatic plexus composing the centre or medullary portion of the gland, from which the efferent vessels emerge. These plexuses of lymphatic vessels are intermixed with a capillary plexus, and the Avhole inclosed in a thin fibro-areolar capsule. Thoracic Duct. The thoracic duct (Fig. 227) conveys the great mass of the lymph and chyle into the blood. It is the common trunk of all the lymphatic vessels of the body, THORACIC DUCT. 427 Ilig/i/ CittrphcrC/c excepting those of the right side of the head, neck, and thorax, and right upper extremity, the right lung, right side of the heart, and the convex surface of the liver. It varies from eighteen to twenty inches in length in the adult, and 1 extends from the second lum- bar vertebra to the root of Fig- 227.—The Thoracic and Right Lymphatic Ducts. the neck. It commences in the abdomen by a triangular dilatation, the receptaculum chyli (reservoir or cistern of Pecquet), Avhich is situated upon the front of the body of the second lumbar vertebra, to the right side and behind the aorta, by the side of the right crus of the Diaphragm. It ascends into the thorax through the aortic opening in the Diaphragm, and is placed in the posterior medias- tinum in front of the vertebral column, lying between the aorta and vena azygos. Op- posite the fourth dorsal ver- tebra it inclines towards the left side and ascends behind the arch of the aorta, on the left side of the oesophagus, and behind the first portion of the left subclavian artery, to the upper orifice of the thorax. Opposite the upper border of the seventh cervical vertebra, it curves doAvn- wards above the subclavian artery, and in front of the Scalenus muscle, so as to form an arch ; and terminates near the angle of junction of the left internal jugular and sub- clavian veins. The thoracic duct, at its commencement, is about equal in size to the dia- meter of a goose-quill, dimi- nishes considerably in its calibre in the middle of the thorax, and is again dilated just before its termination. It is generally flexuous in its course, and constricted at in- tervals, so as to present a varicose appearance. The thoracic duct not unfrequently divides in the middle of its course into tAvo branches of unequal size, Avhich soon reunite, or into several branches, which form a plcxiform interlacement. It occasionally bifurcates, at its upper part, into tAvo branches, the left terminating in the usual manner, the right opening into the left subcla\lan vein, in connection with the right 428 LYMPHATICS. lymphatic duct. The thoracic duct has numerous valves throughout its whole course, but they are more numerous in the upper than in the lower part; at its termination, it is provided Avith a pair of valves, the free borders of which are turned towards the vein, so as to prevent the regurgitation of venous blood into the duct. Branches. The thoracic duct at its commencement receives four or five large trunks from the abdominal lymphatic glands, and also the trunk of the lacteal vessels. Within the thorax, it is joined by the lymphatic vessels from the left half of the wall of the thoracic cavity; and the lymphatics from the sternal and intercostal glands, those of the left lung, left side of the heart,' trachea, and oeso- phagus ; and just before its termination, receives the lymphatics of the left side of the head and neck, and left upper extremity. The Right Lymphatic Duct is a short trunk, about an inch in length, and a line or a line and a half in diameter, which receives the lymph from the right side of the head and neck, the right upper extremity, and right side of the thorax; and terminates at the angle of union of the right subclavian and right internal jugular veins. Its orifice is guarded by two semilunar valves, which prevent the entrance of blood from the veins. Branches. In addition to those already mentioned, it receives the lymphatics of the right lung and right side of the heart, and some from the convex surface of the liver. Lymphatics of the Head, Face, and Neck. The Superficial Lymphatic Glands of the Head (Fig. 228) are of small size, few in number, and confined to its posterior region. They are the occipital, placed at the back of the head along the attachment of the Occipito-frontalis; and the posterior auricular, near the upper end of the Sterno-mastoid. These glands become con- siderably enlarged in cutaneous affections and other diseases of the scalp. In the face, the superficial lymphatic glands are more numerous : they are the parotid, some of which are superficial and others deeply placed in its substance; the zygo- matic, situated under the zygoma; the buccal, on the surface of the buccinator muscle; and the submaxillary, the largest, beneath the body of the lower jaAv. The Superficial Lymphatics of the Head are divided into an anterior and a pos- terior set, Avhich follow the course of the temporal and occipital vessels. The tem- poral set accompany the temporal artery in front of the ear, to the parotid lymphatic glands, from which they proceed to the lymphatic gland of the neck. The occi- pital set follow the course of the occipital artery, descend to the occipital and pos- terior auricular lymphatic glands, and from thence join the cervical glands. The Superficial Lymphatics of the Face are more numerous than those of the head. They commence over its entire surface, those from the frontal region accom- panying the frontal A7essels ; they then pass obliquely across the face, accompanying the facial vein, pass through the buccal glands on the surface of the Buccinator muscle, and join the submaxillary lymphatic glands. These glands receive the lymphatic vessels from the lips, and are often found enlarged in cases of malignant disease of this part. The Deep Lymphatics of the Face are derived from the pituitary mem- brane of the nose, the mucous membrane of the mouth and pharynx, and the contents of the temporal and orbital fossae ; they accompany the branches of the internal maxillary artery, and terminate in the deep parotid and cervical lymphatic glands. The Deep Lymphatics of the Cranium consist of tAvo sets, the menin- geal and cerebral. The meningeal lymphatics accompany the meningeal vessels, escape through the foramina at the base of the skull, and join the deep cervical lym- phatic glands. The cerebral lymphatics are described by Fohmann as being situated between the arachnoid and pia mater, as well as in the choroid plexuses of the lateral ventricles; they accompany the trunks of the carotid and vertebral arteries, and probably pass through foramina at the base of the skull, to terminate OF THE HEAD, FACE, AND NECK. 429 in the deep cervical glands. They have not at present been demonstrated in the dura mater, or m the substance of the brain. The Lymphatic Glands of the Neck are divided into two sets, superficial and deep. The superficial cervical glands are placed in the course of the external jugular vein, between the Platysma and Sterno-mastoid. They are most numerous at the root of the neck, in the triangular interval between the clavicle, the Sterno-mas- toid, and the Trapezius, where they are continuous with the axillary glands. A few small glands are also found on the front and sides of the larynx. Fig. 228.—The Superficial Lymphatics and Glands of the Head, Face, and Neck. The deep cervical glands (Fig. 229) are numerous and of large size ; they form an uninterrupted chain along the sheath of the carotid artery and internal jugular vein, lying by the side of the pharynx, oesophagus, and trachea, and extending from the base of the skull to the thorax, Avhere they communicate Avith the lym- phatic glands in this cavity. The Superficial and Deep Cervical Lymphatics are a continuation of those already described on the cranium and face. After traversing the glands in those regions, they pass through the chain of glands Avhich lie along the sheath of the carotid vessels, being joined by the lymphatics from the pharynx, oesopha- gus, larynx, trachea, and thyroid gland. At the loAver part of the neck, after receiving some lymphatics from the thorax, they unite into a single trunk, which 130 LYMPHATICS. terminates on the left side, in the thoracic duct; on the right side, in the rio-ht lymphatic duct. Fig. 229.—The Deep Lymphatics and Glands of the Neck and Thorax. Lymphatics op the Upper Extremity. The Lymphatic Glands of the upper extremity (Fio*. 230) may be subdivided into two sets, superficial and deep. _ The superficial lymphatic glands are few, and of small size. There are occa- sionally two or three in front of the elbow, and one or tAvo above the internal condyle of the humerus, near the basilic vein. The deep lymphatic glands are also few in number. In the forearm a few small ones are occasionally found in the course of the radial and ulnar vessels; and m the arm, there is a chain of small glands along the inner side of the brachial artery. The Axillary Glands are of large size, and usually ten or twelve in number. A chain of these glands surrounds the axillary-vessels imbedded in a quantity of loose areolar tissue ; they receive the lymphatic vessels from the arm : others are dispersed m the areolar tissue of the axilla : the remainder are arranged in two series, a small chain running along the lower border of the Pectoralis major, as tar as the mammary gland, receiving the lymphatics from the front of the chest and mamma ; and others are placed along the lower margin of the posterior wall OF THE UPPER EXTREMITY. 431 of the axilla, which receive the lymphatics from the integument of the back. Two or three subclavian lymphatic glands are placed immediately beneath the clavicle; it is through these that the axillary and deep cervical glands communi- cate with each other. One is figured by Mascagni near the umbilicus. In malignant diseases, tumors or other affections implicating the upper part of the back and shoulder, the front of the chest and mamma, the upper part of the front and side of the abdomen, or the hand, forearm, and arm, these glands, are usually found enlarged. Fig. 230.—The Superficial Lymphatics and Glands of the Upper Extremity. The Superficial Lymphatics of the upper extremity arise from the skin of the hand, and run along the sides of the fingers, chiefly on the dorsal surface of the hand; they then pass up the forearm, and subdivide into two sets, Avhich take the course of the subcutaneous veins. Those from the inner border of the hand accompanying the ulnar veins along the inner side of the forearm to the bend of the elboAv, Avhere they join with some lymphatics from the outer side of the fore- arm, follow the course of the basilic vein, communicate Avith the glands imme- 432 LYMPHATICS. Fig.231.—The Superficial Lymphatics and Glands of the Lower Extremity. £>A ^ ^vSI Superficial^ Inguinal [ Clanda { ■>/ 1 :i- diately above the elboAv, and terminate in the axillary glands, joining with the deep lymphatics. The superficial lym- phatics from the outer and back part of the hand accompany the radial veins to the bend of the elbow, being less nume- rous than the preceding. Here the greater number join the basilic group; the rest ascend Avith the cephalic vein on the outer side of the arm, some crossing obliquely the upper part of the Biceps to terminate in the axillary glands, whilst one or tAvo accompany the cephalic vein in the cellular interval betAveen the Pec- toralis major and Deltoid, and enter the subclavian lymphatic glands. The Deep Lymphatics of the upper extremity, accompany the deep blood- vessels. In the forearm they consist of three sets, corresponding with the radial, ulnar, and interosseous arteries; they pass through the glands occasionally found in the course of these vessels, and communicate at intervals Avith the super- ficial lymphatics. In their ascent up- Avards, some of them pass through the glands Avhich lie upon the brachial ar- tery ; they then enter the axillary and subclavian glands, and at the root of the neck terminate, on the left side in the thoracic duct, and on the right side in the right lymphatic duct. Lymphatics of the Lower Extre- mity. The Lymphatic Glands of the lower extremity may be subdivided into two sets, superficial and deep. The superficial lymphatic glands of the loAver extremity are confined to the inguinal region. The superficial inguinal glands, placed immediately beneath the integu- ment, are of large size, and vary from eight to ten in number. They are divi- sible into two groups; an upper, dis- posed irregularly along Poupart's liga- ment receiving the lymphatic vessels from the integument of the scrotum, penis, parietes of the abdomen, peri- naeum, and gluteal regions; and an inferior group, Avhich surround the sa- phenous opening in the fascia lata, a feAV being sometimes continued along the saphena vein to a variable extent. These receive the superficial lymphatic OF THE LOWER EXTREMITY. 433 vessels from the lower extremity. These glands frequently become enlarged in diseases implicating the parts from Avhich their efferent lymphatics originate. Thus, in malignant or syphilitic affections of the prepuce and penis, the labia majora in the female, in cancer scroti, in abscess in the perinaeum, or in any other disease affecting the integument and superficial structures in these parts, or the subumbilical part of the abdomen or gluteal region, the upper chain of glands is almost invariably enlarged, the loAver chain being implicated in diseases affecting the lower limb. The Deep Lymphatic Glands are the anterior tibial, popliteal, deep inguinal, gluteal, and ischiatic. The Anterior Tibial Gland is not constant in its existence. It is generally found by the side of the anterior tibial artery, upon the interosseous membrane at the upper part of the leg. Occasionally tAvo glands are found in this situation. The Deep Popliteal Glands, four or five in number, are of small size; they surround the popliteal vessels, imbedded in the cellular tissue and fat of the popli- teal space. The Deep Inguinal Glands are placed beneath the deep fascia around the femoral artery and vein. They are of small size, and communicate with the superficial inguinal glands through the saphenous opening. The Gluteal and Ischiatic Glands are placed, the former above, the latter below the Pyriformis muscle, resting on their corresponding vessels as they pass out of the great sacro-sciatic foramen. The LymjJiatics of the lower extremity, like the veins, may be divided into two sets, superficial and deep. The Superficial Lymphatics are placed between the integument and superficial fascia, and are divisible into two groups, an internal group, which follow the course of the internal saphena vein, and an external group, which accompany the external saphena. The internal group, the largest, commence on the inner side and dorsum of the foot; they pass, some in front and some behind the inner ankle, ascend the leg with the internal saphenous vein, pass Avith it behind the inner condyle of the femur, and accompany it to the groin, where they terminate in the group of inguinal glands which surround the saphenous opening. Some of the efferent Aressels from these glands pierce the cribriform fascia and sheath of the femoral vessels, and terminate in a lymphatic gland contained in the femoral canal, thus establishing a communication between the lymphatics of the lower extremity and those of the trunk ; others pierce the fascia lata, and join the deep inguinal glands. The external group arise from the outer side of the foot, ascend in front of the anterior region of the leg, and just beloAv the knee cross the tibia from without iinvards, to join the lymphatics on the inner side of the thigh. Others commence on the outer side of the foot, pass behind the outer malleolus, and accompany the external saphenous vein along the back of the leg, where they enter the popliteal glands. The Deep Lymj)hatics of the lower extremity are few in number, and accom- pany the deep bloodvessels. In the leg they consist of three sets, the anterior tibial, peroneal, and posterior tibial, which accompany the corresponding vessels, being two or three in number to each; they ascend with the bloodvessels, and enter the lymphatic glands in the popliteal space: the efferent vessels from these glands accompany the femoral vein, and join the deep inguinal glands ; from these the vessels pass beneath Poupart's ligament, and communicate Avith the chain of glands surrounding the external iliac vessels. The deep lymphatics of the gluteal and ischiatic regions follow the course of the bloodvessels, and join the gluteal and ischiatic glands at the great sacro-sciatic foramen. 30 434 LYMPHATICS. Lymphatics of the Pelvis and Abdomen. The Deep Lymphatic Glands in the Pelvis are the external iliac, the internal ilirc, and the sacral. Those of the abdomen are the lumbar glands. The External Iliac Glands form an uninterrupted chain around the external Fig. 232.—The Deep Lymphatic Vessels and Glands of the Abdomen and Pelvis. iliac vessels, three being placed around the commencement of the vessel just behind the crural arch. They communicate by one extremity with the femoral lymphatics, and by the other with the lumbar glands. The Internal Iliac Glands surround the internal iliac vessels; they receive the lymphatics corresponding to the branches of the internal iliac artery, and commu- nicate with the lumbar glands. OF THE PELVIS AND ABDOMEN. 435 The Sacral Glands occupy the sides of the anterior surface of the sacrum, some being situated in the folds of the mesorectum. These and the internal iliac glands become greatly enlarged in malignant disease of the bladder, rectum, or uterus. The Lumbar Glands are very numerous; they are situated on the front of the lumbar vertebrae, surrounding the common iliac vessels, the aorta, and vena cava; they receive the lymphatic vessels from the lower extremities and pelvis, as well as from the testes and some of the abdominal viscera ; the efferent vessels from these glands unite into a few large trunks, which, with the lacteals, form the commencement of the thoracic duct. In some cases of malignant disease, these glands become enormously enlarged, completely surrounding the aorta and vena cava, and occasionally greatly contracting the calibre of these vessels. In all cases of malignant disease of the testis, and in malignant disease of the lower limb, before any operation is attempted, careful examination of the abdomen should be made.in order to ascertain if any enlargement exists, and if any should be detected, all operative measures are fruitless. The Lymphatics of the Pelvis and Abdomen may be divided into tAvo sets, superficial and deep. The Superficial Lymphatics of the Avails of the abdomen and pelvis follow the course of the superficial bloodvessels. Those derived from the integument of the lower part of the abdomen beloAV the umbilicus, follow the course of the superficial epigastric vessels, and converge to the superior group of the superficial inguinal glands; the deep set accompany the deep epigastric vessels, and com- municate with the external iliac glands. The superficial lymphatics from the sides and lumbar part of the abdominal Avail wind round the crest of the ilium, accompanying the superficial circumflex iliac vessels, to join the superior group of the superficial inguinal glands ; the greater number, however, accompanying the ilio-lumbar and lumbar vessels backAvards to join the lumbar glands. The Superficial Lymphatics of the Gluteal Region turn horizontally round the outer side of the nates, and join the superficial inguinal glands. The Superficial Lymphatics of the Scrotum and Perinasum follow the course of the external pudic vessels, and terminate in the superficial inguinal glands. The Superficial Lymphritics of the Penis occupy the sides and dorsum of the organ, the latter receiving the lymphatics from the skin covering the glans penis ; they all converge to the superior group of the superficial inguinal glands. The deep lymphatic vessels of the penis follow the course of the internal pudic vessels, and join the internal iliac glands. In the female, the lymphatic vessels of the mucous membrane of the labia, nymphae, and clitoris, terminate in the superior group of the inguinal lymphatic glands. , The Deep Lymphatics of the Pelvis and Abdomen take the course of the prin- cipal bloodvessels. Those of the parietes of the pelvis. AA'hich accompany the gluteal, ischiatic, and obturator vessels, follow the course of the internal iliac artery, and ultimately join the lumbar lymphatics. The efferent vessels from the inguinal glands enter the pelvis beneath Poupart's ligament, where they lie in close relation with the femoral vein; they then pass through the chain of glands surrounding the external iliac vessels, and finally terminate in the lumbar glands. They receive the deep epigastric, circumflex ilii, and ilio-lumbar lymphatics. The Lymphatics of the Bladder arise from the entire surface of the organ; the greater number run beneath the peritoneum on its posterior surface, and, after passing through the lymphatic glands in this situation, join Avith those from the prostate and vesiculae seminales, and enter the internal iliac glands. The Lymphatics of the Rectum are of large size; after passing through some small glands that lie upon its outer Avail and in the mesorectum, they pass to the sacral or lumbar glands. The Lymphatics of the Uterus consist of two sets, superficial and deep ; the former being placed beneath the peritoneum, the latter in the substance of the 436 LYMPHATICS. organ. The lymphatics of the cervix uteri, together Avith those from the vagina, enter the internal iliac and sacral glands; those from the body and fundus of the uterus pass outAvards in the broad ligaments, and being joined by the lym- phatics from the ovaries, broad ligaments, and Fallopian tubes, ascend with the, ovarian vessels to open into the lumbar glands. In the unimpregnated uterus they are small, but during gestation they become very greatly enlarged. The Lymphatics of the Testicle consist of two sets, superficial and deep; the former commence on the surface of the tunica vaginalis, the latter in the epididymis and body of the gland. They form several large trunks, which ascend Avith the spermatic cord, and accompany the spermatic \-essels into the abdomen, open into the lumbar glands : hence the enlargement of these glands in malignant disease of this organ. The Lymphatics of the Kidney arise on the surface, and also in the interior of the organ; they unite together at the hilus, and after receiving the lymphatic vessels from the ureters and suprarenal capsules, open into the lumbar glands. The Lymphatics of the Liver are divisible into two sets, superficial and deep. The former arise in the subperitoneal areolar tissue over the entire surface of the organ. Those on the convex surface may be divided into four groups: 1. Those which pass from behind forAvards, consisting of three or four trunks, ivhich ascend in the longitudinal ligament, and unite to form a single trunk, Avhich passes up between the fibres of the Diaphragm, behind the ensiform cartilage, to enter the anterior mediastinal glands, and finally ascend to the root of 'the neck, to terminate in the right lymphatic duct. 2. Another group, Avhich also incline from behind forwards, are reflected over the anterior margin of the liver to its concave surface, and from thence pass along the longitudinal fissure to the glands in the gastro-hepatic omentum. 3. A third group incline outAvards to the right lateral ligament, and uniting into one or two large trunks, pierce the Diaphragm, and run along its upper surface to enter the anterior mediastinal glands; or, in- stead of entering the thorax, turns inAvards across the crus of the Diaphragm, and open into the commencement of the thoracic duct. 4. The fourth group in- cline outAvards from the surface of the left lobe of the liver to the left lateral ligament, pierce the Diaphragm, and passing forAvards, terminate in the glands in the anterior mediastinum. The Superficial Lymphatics on the under surface of the Liver may be divided into three sets: 1. Those on the right side of the gall-bladder enter the lumbar glands. 2. Those surrounding the gall-bladder form a remarkable plexus, which accompanies the hepatic vessels, and open into the glands in the gastro-hepatic omentum. 3. Those on the left of the gall-bladder pass to the oesophageal glands, and to those placed along the lesser curvature of the stomach. The Deep Lymphatics accompany the branches of the portal vein and the hepatic artery and duct through the substance of the gland; passing out at the transverse fissure, they enter the lymphatic glands along the lesser curvature of the stomach and behind the pancreas, or join Avith one of the lacteal vessels pre- vious to its termination in the thoracic duct. The Lymphatic Glands of the Stomach are of small size; they are placed along the lesser and greater curvatures, some within the gastro-splenic omentum, whilst others surround its cardiac and pyloric orifices. The Lymphatics of the Stomach consist of tAvo sets, superficial and deep; the former originating in the subserous, and the latter in the submucous coats. They follow the course of the bloodAressels, and may consequently be arranged into three groups. The first group accompany the coronary vessels along the lesser curvature, receiving branches from both surfaces of the organ, and pass to the glands around the pylorus. The second group pass from the great end of the stomach, accompany the A^asa brevia, and enter the splenic lymphatic glands. The third group run along the greater curvature with the right gastro-epiploic vessels, and terminate at the root of the mesentery in one of the principal lacteal vessels. OF THE THORAX. 437 The Lymphatic Glands of the Spleen occupy the hilus. Its lymphatic vessels consist of two sets, superficial and deep; the former being placed beneath its peri- toneal covering, the latter in the substance of the organ : they accompany the bloodvessels, passing through a series of small glands, and after receiving those derived from the pancreas, ultimately passing into the thoracic duct. The Lymphatic System of the Intestines. The Lymphatic Glands of the Small Intestines are placed between the layers of the mesentery, occupying the meshes formed by the superior mesenteric vessels, and hence called mesenteric glands. They vary in number from a hundred and thirty to about a hundred and fifty, and are about the size of an almond. These glands are most numerous, and largest, superiorly near the duodenum, and infe- riorly opposite the termination of the ileum in the colon. This latter group becomes greatly enlarged and infiltrated with deposit in cases of fever accompa- nied with ulceration of the intestines. The Lymphatic Glands of the Large Intestine are much less numerous than the mesenteric glands; they are situated along the vascular arches formed by the arteries previous to their distribution, and even sometimes upon the intestine itself. They are feAvest in number along the transverse colon, where they form an unin- terrupted chain with the mesenteric glands. The Lymphatics of the Small Intestine are called lacteals, from the milk-Avhite fluid they usually contain: they consist of two sets, superficial and deep; the former lie beneath the peritoneal coat, taking a longitudinal course along the outer side of the intestine; the latter occupy the submucous tissue, and course transversely round the intestine, accompanied by the branches of the mesenteric vessels: they pass between the layers of the mesentery, enter the mesenteric glands, and finally unite to form two or three large trunks, Avhich terminate in the thoracic duct. The Lynqdiatics of the Great Intestine consist of two sets: those of the caecum, ascending and transverse colon, Avhich, after passing through their proper glands, enter the mesenteric glands; and those of the descending colon and rectum, which pass to the lumbar glands. The Lymphatics of the Thorax. The Deep Lymphatic Glands of the Thorax are the intercostal, internal mam- mary, anterior mediastinal, and posterior mediastinal. The Intercostal Glands are small, irregular in number, and situated on each side of the spine, near the costo-vertebral articulations, some being placed between the two planes of Intercostal muscles. The Internal Mammary Glands are placed at the anterior extremity of each intercostal space, by the side of the internal mammary vessels. The Anterior Mediastinal Glands are placed in the loose areolar tissue of the anterior mediastinum, some lying upon the Diaphragm in front of the pericardium, and others around the great vessels at the base of the heart. The Posterior Alediastinal Glands are situated in the areolar tissue in the pos- terior mediastinum, forming a continuous chain by the side of the aorta and oesophagus; they communicate on each side with the intercostal, beloAv Avith the lumbar glands, and above Avith the deep cervical. The Superficial LymjJiatics of the front of the Thorax run across the great Pectoral muscle, and those on the back part of this cavity lie upon the Trapezius and Latissimus dorsi; they all converge to the axillary glands. The lymphatics from the mamma run along the loAver border of the Pectoralis major, through a chain of small lymphatic glands, and communicate with the axillary glands. The Deep Lymphatics of the Thorax are the intercostal, internal mammary, and diaphragmatic. The Intercostal Lymphatics folloAv the course of the intercostal vessels, receiving lymphatics from the Intercostal muscles and pleura; they pass backwards to the 438 LYMPHATICS. spine, and unite with lymphatics from the back part of the thorax and spinal canal. After traversing the intercostal glands, they incline doAvn the spine, and terminate in the thoracic duct. The Internal Mammary Lymphatics folloAv the course of the internal mammary vessels : they commence in the muscles of the abdomen above the umbilicus, com- municating with the epigastric lymphatics, ascend betAveen the fibres of the Diaphragm at its attachment to the ensiform appendix, and in their course behind the costal cartilages are joined by the intercostal lymphatics, terminating on the .right side in the right lymphatic duct, on the left side in the thoracic duct. The Lymphatics of the Diaphragm follow the course of their corresponding vessels, and terminate, some in front in the inferior mediastinal and internal mam- mary glands, some behind in the intercostal and hepatic lymphatics. The Bronchial Glands are situated around the bifurcation of the trachea and roots of the lungs. They are ten or twelve in number, the largest being placed opposite the bifurcation of the trachea, the smallest around the bronchi and their primary divisions for some little distance Avithin the substance of the lungs. In infancy, they present the same appearance as lymphatic glands in other situations; in the adult they assume a broAvnish tinge, and in old age a deep black color. Occasionally they become sufficiently enlarged to compress and narroAv the canal of the bronchi; and they are often the seat of tubercle or deposits of phosphate of lime. The Lymphatics of the Lung consist of two sets, superficial and deep: the former are placed beneath the pleura, forming a minute plexus, which covers the outer surface of the lung; the latter accompany the bloodvessels, and run along the bronchi: they both terminate at the root of the lungs in the bronchial glands. The efferent vessels from these glands, tAvo or three in number, ascend upon the trachea to the root of the neck, traverse the tracheal and oesophageal glands, and terminate on the left side in the thoracic duct, on the right side in the right lym- phatic duct. The Cardiac Lymphatics consist of tAvo sets, superficial and deep: the former arise in the subserous areolar tissue of the surface, and the latter beneath the internal lining membrane of the heart. They folloAv the course of the coronary vessels; those of the right side unite into a trunk at the root of the aorta, which, ascending across the arch of that vessel, passes backAvards to the trachea, upon which it ascends, to terminate at the root of the neck in the right lymphatic duct. Those of the left side unite into a single vessel at the base of the organ, which, passing along the pulmonary artery, and traversing some glands at the root of the aorta, ascends on the trachea to terminate in the thoracic duct. The Thymic Lymphatics arise from the spinal surface of the thymus gland, and terminate on each side in the internal jugular veins. The Thyroid Lymphatics arise from either lateral lobe of this organ : they con- verge to form a short trunk, Avhich terminates on the right side in the right lym- phatic duct, on the left side in the throracic duct. The Lymphatics of the (Esophagus form a plexus around that tube, traverse the glands in the posterior mediastinum, and, after communicating with the pulmonary lymphatic vessels near the root of the lungs, terminate in the thoracic duct. Nervous System. THHE Nervous System consists of a series of connected central organs, called, collectively, the cerebrospinal centre or axis, of the ganglia, and of the nerves. The Cerebro-spinal Axis consists of two portions, the brain or encephalon, Avhich is contained within the cranium, and the spinal cord, continuous with the brain, which is inclosed in the spinal canal. The cerebro-spinal centre consists of two lateral symmetrical halves, which correspond in their structure in eA-ery respect; they are partially separated by longitudinal fissures, and connected together by broad transverse bands of nervous substance, called commissures. The cerebro-spinal axis consists of three substances, which differ from each other in density and color; they are called the gray, cineritious or cortical substance, and the white or medullary. The gray or cortical substance is disposed in the form of a thin layer upon the outer surface of the convolutions of the cerebrum and lamina} of the cerebellum ; it is not confined, however, to the external surface, for it exists in the interior of the spinal cord throughout its entire length, and from this part may be traced up through the medulla oblongata, pons Varolii, and crura cerebri, to the central parts of the hemispheres, the optic thalami, and corpora striata. It also forms at the base of the brain, the lamina cinerea, the tuber cinereum, and the gray matter in the anterior and posterior perforated spaces. The gray matter may be traced from the anterior perforated space into the olfactory nerve as far as the bulb, and from the posterior space as forming part of the infundibulum and pituitary body. The gray matter in this situation is continued upon the sides of the thalami, forms the soft commissure, surrounds the anterior pillars of the fornix, enters beloAv into the substance of the corpus albicans ; and, above, forms part of the lateral Avails of the septum lucidum. It is also found in the centre of each of the corpora quad- rigemina, in the pineal gland, and corpora geniculata. It forms also the corpus dentatum in the centre of each lateral lobe of the cerebellum. The white or medullary portion of the cerebro-spinal axis consists of fibres, which are arranged chiefly in a longitudinal direction, or interlace at various angles with transverse fibres; they may be arranged into three classes, ascending, transverse, and longitudinal. The ascending fibres pass up from the medulla oblongata, increase in number as they ascend through the pons, the optic thalami, and striated bodies, and then diverge to every part of the surface of the hemi- spheres. They were called by Gall the diverging fibres. The transverse or com- missural fibres commence at the surface of the hemispheres, and proceed inwards towards the centre, connecting the tAvo hemispheres together; these were named by Call the converging fibres. The longitudinal fibres, also commissural, connect together different parts of the same hemisphere, being confined to the same side of the middle line. Chemical Composition. The folloAA'ing analysis by Lassaigne represents the relative proportion of the different constituents composing the gray and Avhite matter of the brain. Gray. AVhite. Water,.........85*2 73*0 Albuminous matter, ....... 7*5 9*9 Colorless fat,........1*0 13 9 Red fat,.........37 0*9 Osmazome and lactates, ...... 1*4 1*0 Phosphates,........1-2 13 100*0 100 0 410 NERVOUS SYSTEM. It appears from this analysis, that the cerebral substance consists of albumen, dissolved in water, combined with fatty matters and salts. The fatty matters, according to Fre'my, consist of cerebric acid, Avhich is most abundant, cholesterin, oleophosphoric acid, and olein, margarin, and traces of their acids. The same analyst states, that the fat contained in the brain is confined almost exclusively to the white substance, and that its color becomes lost when the fatty matters arc removed. According to Vauquelin, the cord contains a larger proportion of fat than the brain ; and according to L'Heritier, the neiwes contain more albumen and more soft fat than the brain. The Ganglia may be regarded as separate and independent nervous centres, of smaller size and less complex structure than the brain, connected Avith each other, with the cerebro-spinal axis, and with the nerves in various situations. They are found on the posterior root of each of the spinal nerves ; on the posterior or sensory root of the fifth cranial nerve ; on the seventh nerve ; on the two sensory divisions of the eighth pair (the glosso-pharyngeal and pneumogastric); in a connected series along each side of the vertebral column, forming the trunk of the sympathetic ; on the branches of this nerve in the head, neck, thorax, and abdo- men ; or at the point of junction of branches of this nerve Avith the cerebro- spinal nerves. On section, they are seen to consist of a reddish-gray substance, traversed by numerous Avhite nerve-fibres: they vary considerably in form and size ; the largest are those found in the cavity of the abdomen ; the smallest, the microscopic ganglia, Avhich exist in considerable numbers upon the nerves distri- buted to the different viscera. The ganglia are invested by a smooth and firm closely adhering membranous envelope, consisting of dense areolar tissue ; this sheath is continuous Avith the neurilemma of the nerves, and sends numerous pro- cesses into the interior of the ganglia, which support the bloodvessels supplying its substance. The Nerves are round or flattened Avhite cords, communicating on the one hand with the cerebro-spinal centre or the ganglia, and by the other distributed to the various textures of the body, forming the medium of communication between the two. One class of nerve-fibres, the afferent or centripetal, serve to convey im- pressions to the brain, the great centre of sensation and volition, where they are rendered cognizable to the mind ; Avhilst another class of nerve-fibres, the efferent or centrifugal, convey the stimulus of volition to the organs of motion. The brain and spinal cord are also capable of receiA'ing impressions by means of the afferent nerve-fibres, which results in a motorial stimulus being propagated along the efferent nerves, quite independent of the efforts of volition, and Avithout even consciousness. The movements of this kind are called reflex or excito-motory. The nerves are subdivided into tAvo great classes, the cerebro-spinal, which proceed from the cerebro-spinal axis, and the sympathetic or ganglionic nerves, which proceed from the sympathetic ganglia ; the cerebro-spinal are the nerves of animal life, being distributed to the organs of the senses, the skin, and to the active organs of locomotion, the muscles. The sympathetic or ganglionic nerves are distributed chiefly to the viscera and bloodvessels, and are termed the nerves of organic life. The cerebro-spinal nerves consist of numerous nerve-fibres, collected together and inclosed in a membranous sheath. A small bundle of primitive fibres inclosed in a tubular sheath is called a funieidus: if the nerve is of small size, it may consist only of a single funiculus, but if large, the funiculi are collected together into larger bundles or fasciculi; and one or more fasciculi bound together in a common membranous investment, termed the sheath, constitute a nerve. In structure, the common sheath investing the Avhole nerve, as Avell as the septa given off from it, Avhich separate the fasciculi, consists of areolar tissue, com- posed of the Avhite and yellow elastic fibres, the latter existing in greatest abun- dance. The tubular sheath of the funiculi, or neurilemma, consists of a fine smooth transparent membrane, which may be easily separated, in the form of a tube, from the fibres it incloses ; in structure, it is, for the most part, a simple GENERAL ANATOMY. 441 and homogeneous transparent film, occasionally composed of numerous minute reticular fibres. The nerve-fibres, as far as is at present known, do not coalesce, but pursue an uninterrupted course from the centre to the periphery. In dissecting a nerve, however, into its component funiculi, it may be seen that they do not pursue a perfectly insulated course, but occasionally join at a very acute angle with other funiculi proceeding in the same direction; from these again branches are given off, which join again in like manner Avith other funiculi. It must be remembered, however, that in these communications the nerve-fibres do not coalesce, but merely pass into the sheath of the adjacent nerve, become intermixed with the nerve- fibres, and again pass on to become blended Avith the nerve-fibres in some adjoining fasciculus. The cerebro-spinal nerves consist almost exclusively of the tubular nerve-fibres, the gelatinous fibres existing in very small proportion. The bloodvessels supplying a nerve terminate in a minute capillary plexus, the vessels composing which run, for the most part, parallel with the funiculi; they are connected together by short transverse vessels, forming narrow oblong meshes, similar to the capillary system of the muscle. Nerves in their course subdivide into branches, and these frequently commu- nicate with branches of a neighboring nerve. In the subdivision of a nerve, the filaments of which it is composed are continued from the trunk into the branches, and, at their junction Avith the branches of neighboring nerves, the filaments pass to become intermixed Avith those of the other nerve in their further progress ; in no instance, hoAvever, do the separate nerve-fibres either subdivide or inosculate. The communications Avhich take place betAveen two or more nerves form what is called a plexus. Sometimes a plexus is formed by the primary branches of the trunks of the nerves, as the cervical, brachial, lumbar, and sacral plexuses, and occasionally by the terminal fasciculi, as in the plexuses formed at the periphery of the body. In the formation of a plexus, the component nerves divide, then join and again subdivide in such a complex manner that the individual fasciculi become interlaced most intricately; so that each branch leaving a plexus may con- tain filaments from each of the primary nervous trunks which form it. In the formation also of the smaller plexuses at the periphery of the body, there is a free interchange of the fasciculi and primitive fibrils. In each case, hoAvever, the individual filaments remain separate and distinct, neither subdividing nor inos- culating. Some nerve-fibres have no peripheral termination. Gerber has shoAvn, that nenre-fibres occasionally form loops by their junction with a neighboring fibre in the same fasciculus, and return to the cerebro-spinal centre without having any peripheral termination. These he considers to be sentient nerves, appropriated exclushrely to the nerve itself, the nervi nervorum, upon Avhich the sensibility of the nerve depends, and quite exclusive of the sensation produced by an impression made at the peripheral end of the nerve. These fibres bear some analogy to those met with in the posterior part of the optic commissure, Avhere a set of fibres pass from one optic tract across the commissure to the opposite tract, having no com- munication with the optic nerve ; also in the communications formed betAveen the cervical nerves and spinal accessory and descendens noni, the nerve-fibres form an arch connected by each extremity with the cerebro-spinal centre, and have no peripheral termination. Again, some nerve-fibres would appear to have no central connection with the cerebro-spinal centre, as those forming the most anterior part of the optic com- missure. These interretinal fibres, as they are called, commence in the retina, pass along the optic nerve, and across the commissure to the optic nerve and retina of the opposite side. The point of connection of a nerve with the brain or spinal cord is called, for convenience of description, its origi?i or root. If the fasciculi of Avhich the nerve is composed should all arise at or near one point, or along one tract, the root is 412 NERVOUS SYSTEM. called single. If, on the contrary, the fasciculi divide into tivo separate bundles, Avhich are connected at two different points with any part of the cerebro-spinal centre, such nerve is said to have a double origin, or to arise by two roots, each of which may have a separate function, as in the spinal nerves. The point where the separate fasciculi of a nerve are connected to the surface of the cerebro-spinal centre is called the apparent origin of a nerve ; the term real or deep origin being given to that part of the centre from which a nerve actually springs. The nerve-fibres at the periphery terminate in a varied manner. Occasionally the elementary fibres are disposed in terminal loops or plexuses, Avhich, for a con- siderable period, was supposed to be their usual mode of termination, but later investigations have shoAvn that such is not the case. Nerve-fibres most commonly terminate by blunted and slightly swollen ends, such as is observed in those Avhich enter into the Paccinian bodies, or they may become gradually lost to view in the tissue in Avhich they are distributed, becoming diminished in size, and their tubular sheath and white substance being wanting. Occasionally the elementary nerve-fibres, as in the nerves of special sense, may be brought into connection at their periphery with cells similar to those met with in the gray matter of the brain and ganglia. The Sympathetic System consists of numerous parts, which may be arranged as follows. 1. A connected series of ganglia placed along both sides of the spinal column, from the cranium above to the coccyx beloAV. 2. Branches of commu- nication passing between the ganglia. 3. Branches of connection between the ganglia and the cranial and spinal nerves. 4. Primary branches of distribution, remarkable for their plexiform communications on the vessels, glands, and neigh- boring viscera to which they are distributed, or for passing to other larger ganglia, situated in each of the great cavities of the body, and usually placed on the roots of origin of the larger bloodvessels. 5. Plexuses of nerves proceeding from these secondary ganglia, accompanying the bloodvessels, and receiving branches from the spinal or cerebral nerves. The sympathetic nerves consist of tubular and gelatinous fibres, intermixed with a varying proportion of filamentous areolar tissue, and inclosed in a sheath formed of fibro-areolar tissue. The tubular fibres are, for the most part, smaller than those composing the cerebro-spinal nerves; their double contour is less distinct, and, according to Remak, they present nuclei similar to those found in the gelatinous nerve-fibres. Those branches of the sympathetic which present a well-marked gray color, are composed more espe- cially of gelatinous nerve-fibres, intermixed with feAV tubular fibres : whilst those of a white color contain more of the tubular fibres, and few gelatinous. Occa- sionally the gray and Avhite cords run together in a single nerve, without any intermixture, as in the branches of communication between the sympathetic ganglia and the spinal nerves, or in the communicating cords between the ganglia. The Cerebro-spinal Centre consists of tAvo parts, the spinal cord and the ence- phalon : the latter may be subdivided into the cerebrum or brain proper, the cere- bellum or little brain, the tuber annulare or pons Varolii, and the medulla oblongata. The Spinal Cord and its Membranes. Dissection. To dissect the cord and its membranes, it will be necessary to lay open the whole length of the spinal canal. For this purpose, the muscles must be separated from the vertebral grooves, so as to expose the spinous processes and laminae of the vertebras; and the latter must be sawn through on each side, close to the roots of the transverse processes, from the third or fourth cervical vertebra, above, to the sacrum below. The vertebral arches having been displaced, by means of a chisel, and the separate fragments removed, the dura mater will be exposed, covered by a plexus of veins and a quantity of loose areolar tissue, often in- filtrated with serous fluid. The arches of the upper vertebrse are best divided by means of a strong pair of forceps. Membranes of the Cord. The membranes which envelope the spinal cord are three in number. The MEMBRANES OF THE CORD. 443 233.—The Spinal Cord and its Membranes. most external is the dura mater, a strong fibrous membrane, which forms a loose sheath around the cord. The most internal is the pia mater, a cellulo-vascular membrane, Avhich closely invests the entire surface of the cord. BetAveen the two is the arachnoid membrane, an intermediate serous sac, which envelopes the cord, and is then reflected on the inner surface of the dura mater. The Dura Mater of the cord, continuous Avith that Avhich invests the brain, is a loose sheath Avhich surrounds it, being sepa- rated from the bony Avails of the spinal canal by a Fic quantity of loose areolar adipose tissue, and a plexus of veins. It is attached, above, to, the cir- cumference of the foramen magnum, and extends, beloAv, as far as the top of the sacrum; but, be- yond this point, it is impervious, being continued, in the form of a slender cord, to the back of the coccyx, where it blends Avith the periosteum. This sheath is much larger than is necessary for its con- tents, and its size is greater in the cervical and lumbar regions, than in the dorsal. Its inner sur- face is smooth, being lined by the arachnoid membrane; and on each side may be seen the double openings Avhich transmit the tAvo roots of the corresponding spinal nerve, the fibrous layer of the dura mater being continued in the form of a tubular prolongation on them as they issue from these apertures, and becoming lost upon them. These prolongations of the dura mater are short in the upper part of the spine, but become gradu- ally longer beloAv, forming a number of tubes of fibrous membrane, Avhich inclose the sacral nerves, and are contained in the spinal canal. The chief peculiarities of the dura mater of the cord, as compared with that investing the brain, are the following :— The dura mater of the cord is not adherent to the bones of the spinal canal, Avhich have an independent periosteum. It does not send partitions into the fissures of the cord as in the brain. Its fibrous laminae do not separate, to form venous sinuses, as in the brain. Structure. The dura mater consists of white fibrous tissue, arranged in bands, Avhich intersect one another. It is sparingly supplied with vessels, as compared with the dura mater of the brain; and no nerves have as yet been traced into it. The Arachnoid is exposed by slitting up the dura mater, and reflecting this membrane on either side (Fig. 233). It is a thin, delicate, serous membrane, which invests the outer surface of the cord, and is then reflected upon the inner surface of the dura mater, to which it is intimately adherent. That portion wliich surrounds the cord, is called the visceral layer of the arachnoid; and that wliich lines the inner surface of the dura mater, the parietal layer; the interval betAveen the tAvo, is called the cavity of the arachnoid. The visceral layer forms a loose sheath around the cord, so as to leave a considerable interval betAveen the two, which is called the subarachnoidcan space. This space is largest at the lower Fig. 234.—Transverse Section of the Spinal Cord and its Membranes. Eura.-TWatAT' -JPort£.talLay&r ■tTO/XJ.a.ye.T LUl' Dt.3ita.tw/fV P'Ue-mater 414 NERVOUS SYSTEM. part of the spinal canal, and incloses the mass of nerves which form the cauda equina. It contains an abundant serous secretion, the cerebro-spinal fluid and usually communicates Avith the general ventricular cavity of the brain, by means of an opening in the fibrous layer of the inferior boundary of the fourth ven- tricle. This secretion is sufficient in amount to expand the arachnoid membrane so as to completely fill up the Avhole of the space included in the dura mater. The subarachnoidean space is crossed, at the back part of the cord, by numerous fibrous bands, Avhich stretch from the arachnoid to the pia mater, especially in the cervical region, and is partially subdivided by a longitudinal membranous parti- tion, which serves to connect the arachnoid with the pia mater, opposite the posterior median fissure. This partition is incomplete and cribriform in struc- ture, consisting of bundles of white fibrous tissue, interlacing Avith each other. The visceral layer of the arachnoid surrounds the spinal nerves where they arise from the cord, and incloses them in a tubular sheath as far as their point of exit from the dura mater, Avhere it becomes continuous with the parietal layer. The arachnoid is not very vascular. No nerves have as yet been traced into this membrane. The Pia Mater of the cord is exposed on the remoA'al of the arachnoid (Fig. 233). It is less vascular in structure than the pia mater of the brain, with which it is continuous, being thicker, more dense in structure, and composed of fibrous tissue, arranged in longitudinal bundles. It covers the entire surface of the cord, to which it is very intimately adherent, forming its neurilemma, and sends a process downwards into its anterior fissure, and another, extremely delicate, into the posterior fissure. It also forms a sheath for each of the filaments of the spinal nerves, and invests the neiwes themselves. A longitudinal fibrous band extends along the middle line on its anterior surface, called by Haller, the linea splendens; and a somewhat similar band, the ligamentum denticulatum, is situated on each side. At the point where the cord terminates, the pia mater becomes contracted, and is continued doAvn as a long, slender filament, Avhich descends through the centre of the mass of nerves forming the cauda equina, and is blended with the impervious sheath of dura mater (before mentioned), on a level Avith the top of the sacral canal. It assists in maintaining the cord in its position during the movements of the trunk, and is from this circumstance called the central liga- ment of the spinal cord. It contains a little nervous substance, which may be traced for some distance into its upper part, and is accompanied by a small artery and vein. Structure. The pia mater of the cord, though less vascular than that which invests the brain, contains a network of delicate vessels in its substance. It is also supplied with nerves, Avhich, according to Purkinje, are derived from the sympathetic; but Kemak states that they are chiefly supplied from the posterior roots of the spinal nerves. At the upper part of the cord, it presents a grayish, mottled tint, which is owing to yellowish or broAvn pigment-cells being scattered within its tissue. The Ligamentum Denticulatum (Fig. 233) is a narrow, fibrous band, situated on each side of the spinal cord, throughout its entire length, and separating the ante- rior from the posterior roots of the spinal nerves, having received its name from the serrated appearance which it presents. Its inner border is continuous Avith the pia mater, at the side of the cord. Its outer border presents a series of triangular, dentated serrations, the points of which are fixed, at intervals, to the dura mater, serving to unite together the two layers of the arachnoid membrane. These serrations are about twenty in number, on each side, the first being attached to the dura mater, opposite the margin of the foramen magnum, between the verte- bral artery and the hypoglossal nerve; and the last corresponds to nearly the lower end of the cord. Its use is to support the cord in the fluid by which it is surrounded. SPINAL CORD. 415 The Spinal Cord. The spinal cord (medulla spinalis) is that elongated part of the cerebro- spinal axis, which is contained in the spinal canal. It A\-eighs, when divested of its membranes and nerves, about one ounce and a half, its proportion to the encephalon being about 1 to 33. It does not nearly fill the canal in Avhich it is contained, its investing membranes being separated from the bony walls of the canal by areolar tissue and a plexus of veins. It occupies, in the adult, the upper two-thirds of the spinal canal, extending from the foramen mag- num to the lower border of the body of the first lumbar vertebra, Avhere it terminates in a pointed extremity Avhich is concealed among the leash of nerves forming the cauda equina. In the foetus, before the third month, it reaches to the bottom of the vertebral canal; but, after this period, it gradually recedes from below, as the groAvth of the bones composing the canal is more rapid in propor- tion than the cord; so that, in the child at birth, it extends as far as the third lumbar vertebra. Its position varies according to the degree of curvature of the spinal column, being raised somewhat in flexion of the spine forAvards. Its length varies from fifteen to eighteen inches, and it presents a difference in its diameter in different parts, being marked by two enlargements, an upper or cervical, and a loAver or lumbar. The cervical enlargement, which is the larger, extends from the third cervical to the first dorsal vertebra: its greatest diameter is in the transverse direction, and it corresponds with the origin of the nerAres Avhich supply the upper extremities. The lower, or lumbar enlargement, is situated opposite the last dorsal vertebra, its greatest diameter being from before back- wards. It corresponds Avith the origin of the nerves Avhich supply the loAver extremities. In form, the spinal cord is a flattened cylinder. Its anterior surface presents, along the middle line, a longitudinal fissure, the anterior median fissure ; and, on its posterior surface, another fissure exists, which also extends along the entire length of the cord, the posterior median fissure. These fissures serve to divide the cord into tAvo equal and symmetrical portions, Avhich are connected together throughout their entire length, by a transverse band of nervous sub- stance, the commissure. The Anterior median fissure is wider, but of less depth than the posterior, extending into the cord for about one-thircl of its thickness, and is deepest at the lower part of the cord. It contains a prolonga- tion from the pia mater ; and its floor is formed by the anterior Avbite commissure, which is perforated by numerous bloodvessels, which pass to the centre of the cord. The Posterior median fissure is much more deli- cate than the anterior, and more distinct at the upper part of the cord than below. It extends into the cord to about one-half of its depth. It contains a very slender process of the pia mater and numerous bloodvessels, and its floor is formed by a thin layer of white substance, the posterior Avhite commissure. Some anatomists state, that the bottom of this fissure corresponds to the gray matter, except in the cervical region, and at a point corresponding to the enlargement in the lumbar region. On either side of the anterior median fissure, a linear series of foramina may be observed, indicating the points where the anterior roots of the spinal nerves emerge from the cord. This is called, by some anatomists, the anterior lateral fissure of the cord, although no actual fissure exists in this situation. And on either side of the posterior median fissure, along the line of attachment of the posterior root of the nerves, a delicate fissure may be seen, leading down to the gray matter which approaches the surface in this situation : this is called the posterior lateral fissure Fig. 235. Plan Column -Spinal Cord. Side View. of the Fissures and 446 NERVOUS SYSTEM. of the spinal cord. On the posterior surface of the spinal cord, on either side of the posterior median fissure, is a slight longitudinal furrow, marking off tivo slender tracts, the posterior median columns. These are most distinct in the cervical region, but are stated by Foville to exist throughout the Avhole length of the cord. The fissures divide each half of the spinal cord into four columns, an an- terior column, a lateral column, a posterior column, and a posterior median column. The Anterior column includes all the portion of the cord betAveen the anterior median fissure and the anterior lateral fissure, from which the anterior roots of the nerves arise, and is continuous with the anterior pyramid of the medulla oblongata. The Lateral column, the largest segment of the cord, includes all the portion betAveen the anterior and posterior lateral fissures. It is continuous with the lateral column of the medulla. By some anatomists, the anterior and lateral columns are included together, under the name of the antero-lateral column, which forms rather more than tAvo-thirds of the entire circumference of the cord. The Posterior column is situated betAveen the posterior median and poste- rior lateral fissures. It is continued, above, into the restiform body of the medulla. The Posterior median column is that narroAv segment of the cord which is seen on each side of the posterior median fissure, usually included with the preceding, as the posterior column. If a transverse section of the spinal cord be made, it Avill be seen to consist of white and gray nervous matter. The Avhite matter is situated at the circum- ference, the gray matter in the interior. The Gray matter presents tAvo crescentic masses, placed one in each lateral half of the cord, with their convexities towards one another, and joined by a transverse band of gray matter, the gray commissure. Each crescentic mass has an anterior and posterior horn. The posterior horn is long and narroAv, and approaches the surface at the pos- terior lateral fissure, near which it presents a slight enlargement. The gray mat- ter, in this situation, is pale and soft, and was called by Rolando, the substantia cinerca gelatinosa, being surrounded by a layer of reddish-brown substance. The anterior horn is short and thick, and does not quite reach the surface, but extends towards the point of attachment of the anterior roots of the nerves. Its margin presents a dentate, or stellate appearance. OAving to this peculiar arrange- ment of the gray matter, the anterior and posterior horns projecting towards the surface, each half of the cord is divided, more or less completely, into three columns, anterior, middle, and posterior; the anterior and middle being joined, as the anterior horn does not quite reach the surface, to form the antero-lateral column. The Gray commissure, which connects the two crescentic masses of gray mat- ter, is separated from the bottom of the anterior median fissure by a thick layer of white substance, the anterior Avhite commissure; and, from the bottom of the pos- terior fissure by the posterior Avhite commissure. The existence of the latter com- missure is doubted by some anatomists. The gray commissure consists of a trans- verse band of gray matter, and of white fibres, derived from the opposite half of the cord and the posterior roots of the nerves. The white commissure is formed, partly of fibres from the anterior column, and partly from the fibrils of the an- terior roots of the spinal nerves, which decussate as they pass across from one to the other side. The mode of arrangement of the gray matter, and its amount in proportion to the white, vary in different parts of the cord. Thus, the posterior horns are long and narrow, in the cervical region; short and narrower, in the dorsal; short, but wider, in the lumbar region. In the cervical region, the crescentic portions are small, the white matter more abundant than in any other region of the cord. In the dorsal region, the gray matter is least developed, the white matter being also small in quantity. In the lumbar region, the gray matter is more abundant than MEMBRANES OF THE BRAIN. 447 in any other region of the cord. Towards the lower end of the cord, the white matter gradually ceases. The crescentic portions of the gray matter graduallv blend into a single mass, which forms the only constituent of its extreme point. The white matter of the cord forms about seven-eighths of its entire substance. It is composed of parallel fibres collected into compressed, longitudinal bundles, between which bloodvessels, supported by a delicate process of pia mater, paSS transversely into the Sub- Fig. 236.—Transverse Sections of stance of the cord. the Cort1* In the foetus, until after the sixth month, a canal, continuous with the general ventricular cavity of the brain, extends throughout the entire length of the spinal cord, formed by the closinsr-in of a pre- i •/ o i Opposite Meddle cf Cervical reel2 viously open groove. J- In the adult, this canal can only be seen at the upper part of the cord, extending from the point of the calamus scriptorius, in the floor of the fourth ventricle, for about half an inch doAvn the centre of the cord, where it terminates in a cul-de-sac, the 0}>Ilosiu remnant of the canal being just visible, in a section of the cord, as a small, pale spot, corresponding to the centre of the gray commissure, its cavity having become obliterated. In some cases this canal remains pervious throughout the whole length 0pPo.iu x^tC region. of the cord. The Brain and its Membranes. Dissection. To examine the brain with its membranes, the skull-cap should first be re- moved. This may be effected by sawing through the external table, commencing, in front, about an inch above the margin of the orbit, and extending behind, to a level with the occi- pital protuberance. The internal table must then be broken through with the chisel and hammer to prevent injury to the investing membranes or brain, and after haviug been loosened, it should be forcibly detached, when the dura mater will be exposed. The adhesion between the bone and the dura mater is very intimate, and much more so in the young subject than iu the adult. The membranes of the brain are the dura mater, arachnoid membrane, and pia mater. Dura Mater. The dura mater is a thick and dense inelastic fibrous membrane, Avhich lines the interior of the skull. Its outer surface is rough and fibrillated, and adheres closely to the inner surface of the bones, forming their internal periosteum ; this adhesion being more intimate opposite the sutures and at the base of the skull, where it is attached to the margin of the foramen magnum, and is here continuous Avith the dura mater lining the spinal canal. Its inner surface is smooth and epithe- liated, being lined by the parietal layer of the arachnoid. The dura mater is therefore a fibro-serous membrane, composed of an external fibrous lamella, and an internal serous layer. It sends numerous processes inAvards, into the cavity of the skull, for the support and protection of the different parts of the brain; it is also prolonged to the outer surface of the skull, through the various foramina which exist at its base, Avhere it is continuous Avith the peri- cranium, and its fibrous layer forms sheaths for the nerA'es Avhich pass through these apertures. At the base of the skull, it sends a fibrous prolongation into the foramen caecum; it lines the olfactory groove, and sends a series of tubular pro- longations around the filaments of the olfactory nerves as they pass through the cribriform foramina ; a prolongation is also continued through the sphenoidal fissure into the orbit, and another is continued into the same cavity through the optic foramen, forming a sheath for the optic neiwe, Avhich is continued as far as 118 NERVOUS SYSTEM. the eyeball. In certain situations in the skull already mentioned, the fibrous layer of this membrane subdivides into two, to form the sinuses for the passage of venous blood. Upon the upper surface of the dura mater, in the situation of the longitudinal sinus, may be seen numerous small whitish bodies, the glandule Pacchioni. Structure. The dura mater consists of white fibrous and elastic tissues, arranged in flattened laminae, which intersect one another in every direction. Its arteries are very numerous, but are chiefly distributed to the bones. Those found in the anterior fossa arc the anterior meningeal, from the anterior and pos- terior ethmoidal, and internal carotid. In the middle fossa are the middle and small meningeal, from the internal maxillary, and a third branch from the ascending pharyngeal, Avhich enters the skull through the foramen lacerum basis cranii. In the posterior fossa are the posterior meningeal branch of the occipital, which enters the skull through the jugular foramen, the posterior meningeal, from the vertebral, and occasionally meningeal branches from the ascending pharyngeal which enter the skull, one at the jugular foramen, the other at the anterior condy- loid foramen. The veins AA'hich return the blood from the dura mater and partly from the bones anastomose with the diploic veins. These vessels terminate in the various sinuses, with the exception of tAvo Avhich accompany the middle meningeal artery: these pass from the skull at the foramen spinosum. The nerves of the dura mater are the recurrent branch of the fourth, and fila- ments from the Gasserian ganglion, the ophthalmic nerve, and sympathetic. The so-called Glandulae Pacchioni are numerous small whitish granulations, usually collected into clusters of variable size, which are found in the folloAving situations : 1. Upon the outer surface of the dura mater, in the vicinity of the superior longitudinal sinus, being received into little depressions on the inner sur- face of the calvarium. 2. On the inner surface of the dura mater. 3. In the supe- rior longitudinal sinus. 4. On the pia mater near the margin of the hemispheres. These bodies are not glandular in structure, but consist of a fibro-cellular matrix originally developed from the pia mater: by their growth they produce absorption or separation of the fibres of the dura mater; in a similar manner they make their way into the superior longitudinal sinus, where they are covered by the lining membrane. The cerebral layer of the arachnoid in the situation of these growths is usually thickened and opaque, and adherent to the parietal portion. These bodies are not found in infancy, and very rarely until the third year. They are usually found after the seventh year; and from this period they increase in number as age advances. Occasionally they are Avanting. Processes of the Dura Mater. The processes of the dura mater, sent inAvards into the cavity of the skull, are three in number, the falx cerebri, the tentorium cerebelli, and the falx cerebelli. The falx cerebri, so named from its sickle-like form, is a strong arched process of the dura mater, Avhich descends vertically in the longitudinal fissure between the tAvo hemispheres of the brain. It is narrow in front, where it is attached to the crista galli process of the ethmoid bone, and broad behind, where it is con- nected with the upper surface of the tentorium. Its upper margin is convex, and attached to the inner surface of the skull as far back as the internal occipital pro- tuberance. In this situation it is broad, and contains the superior longitudinal sinus.^ Its lower margin is free, concave, and presents a sharp curved edge which contains the inferior longitudinal sinus. The tentorium cerebelli, so named from its tent-like form, is a roof of dura mater, elevated in the middle, and inclining downwards towards its circumference. It covers the upper surface of the cerebellum, supporting the posterior lobes of the brain, and preventing their pressure upon it. It is attached behind, by its convex border, to the transverse ridges upon the inner surface of the occipital bone, and there incloses the lateral sinuses; in front, to the superior margin of the petrous MEMBRANES OF THE BRAIN. 449 portion of the temporal bone, inclosing the superior petrosal sinuses, and from the apex of this bone, on each side, is continued into the anterior and posterior clinoid processes. _ Along the middle line of its upper surface, the posterior border of the falx cerebri is attached, the straight sinus being placed at their point of junction. Its anterior border is free and concave, and presents a large oval opening for the transmission of the crura cerebri. The falx cerebelli is a small triangular process of dura mater, received into the indentation betAveen the tAvo lateral lobes of the cerebellum behind. Its base is attached, above, to the under and back part of the tentorium; its posterior margin, to the lower division of the vertical crest on the inner surface of the occipital bone. As it descends, it sometimes divides into tAvo smaller folds, which are lost on the sides of the foramen magnum. Arachnoid Membrane. The arachnoid (apdyv-q, eldos, "like a spider's web"), so named from its extreme thinness, is the serous membrane which envelopes the brain, and is then reflected on the inner surface of the dura mater. Like other serous membranes, it is a shut sac, and consists of a parietal and a visceral layer. The parietal layer covers the inner surface of the dura mater, to which it is very, intimately adherent, and gives this membrane the smooth and polished surface which it presents; it is also reflected over those processes which separate the hemispheres of the brain and cerebellum. The visceral layer invests the brain more loosely, being separated from direct contact with the cerebral matter by the pia mater, and a quantity of loose areolar tissue, the subarachnoidean. On the upper surface of the cerebrum the arachnoid is thin and transparent, and may be easily demonstrated by injecting a stream of air beneath it by means of a blowpipe ; it passes over the convolutions Avithout dipping doAvn into the sulci between them. At the base of the brain, the arach- noid is thicker, and slightly opaque towards the central part; it coArers the ante- rior lobes, is ^ extended across betAveen the two middle lobes, so as to leave a considerable interval betAveen it and the brain, the anterior subarachnoidean space; it is closely adherent to the pons and under surface of the cerebellum, but betAveen the hemispheres of the cerebellum and the medulla oblongata another considerable interval is left between it and the brain, called the posterior subarach- noidean space. These tAvo spaces communicate together across the crura cerebri. The arachnoid membrane surrounds the nerves Avhich arise from the brain, and incloses them in loose sheaths as far as their point of exit from the skull, where it becomes continuous Avith the parietal layer. The Subarachnoid Space is the interval left between the arachnoid and pia mater:^ this space is narroAv on the surface of the hemispheres, but at the base of the brain a Avide interval is left betAveen the tAvo middle lobes, and behind, betAveen the hemispheres of the cerebellum and the medulla oblongata. This space is the seat of an abundant serous secretion, the cerebro-spinal fluid, Avhich fills up the interval betAveen the arachnoid and pia mater. The subarachnoid space usually communicates with the general ventricular cavity of the brain, by means of an opening in the inferior boundary of the fourth ventricle. The sac of the arachnoid also contains serous fluid; this is, however, small in quantity compared Avith the cerebro-spinal fluid. Structure. The arachnoid consists of bundles of Avhite fibrous and elastic tissues intimately blended together. The visceral portion is covered Avith a layer of scaly epithelium. It is almost destitute of vessels, and the existence of nerves in it has not been satisfactorily demonstrated. The Cerebro-spinal Fluid fills up the subarachnoid space, keeping the opposed surfaces of the arachnoid membrane in contact. It is a clear limpid fluid, haA-ing a saltish taste, and a slightly alkaline reaction. According to Lassaigne, it con- sists of !l8*o parts of Avater, the remaining 1*5 per cent, being solid matters, animal and saline. It varies in quantity from two to ten ounces, being most 450 NERVOUS SYSTEM. abundant in old persons, and is quickly reproduced. Its chief use is probably to afford mechanical protection to the nervous centres, and to prevent the effects of concussions communicated from Avithout. Pia Mater. The pia mater is a vascular membrane, and derives its blood from the interna] carotid and vertebral arteries. It consists of a minute plexus of bloodvessels held together by an extremely fine areolar tissue. It invests the entire surface of the brain, dipping doAvn betAveen the convolutions and laminae, and is prolonged into the interior, forming the velum interpositum and choroid plexuses of the fourth ventricle. Upon the surface of the hemispheres, Avhere it covers the gray matter of the convolutions, it is very vascular, and gives off from its inner surface a multitude of minute vessels, Avhich extend perpendicularly for some distance into the cerebral substance. At the base of the brain, in the situation of the sub- stantia perforata and locus perforatus, a number of long straight vessels are given off, Avhich pass through the AA'hite matter to reach the gray substance in the inte- rior. On the cerebellum, the membrane is more delicate, and the vessels from its inner surface are shorter. Upon the crura cerebri and pons Varolii its characters are altogether changed ; it here presents a dense fibrous structure, marked only by slight traces of vascularity. • According to Fohman and Arnold, this membrane contains numerous lym- phatic vessels. Its nerves arc derived from the sympathetic, and also from the third, sixth, seventh, eighth, and accessorius. They accompany the branches of the arteries. The Brain. The brain (encephalon) is that portion of the cerebro-spinal axis that is con- tained in the cranial cavity. It is divided into four principal parts, viz.: the cerebrum, the cerebellum, the pons Varolii, and the medulla oblongata. The Cerebrum forms the largest portion of the encephalic mass, and occupies a considerable part of the cavity of the cranium, resting in the anterior and middle fossae of the base of the skull, and separated posteriorly from the cere- bellum by the tentorium cerebelli. About the middle of its under surface is a narrow constricted portion, part of which, the crura cerebri, is continued onwards into the pons Varolii below, and through it to the medulla oblongata and spinal cord; whilst another portion, the crura cerebelli, passes down into the cerebellum. The Cerebellum (little brain or after-brain) is situated in the inferior occipital fossae, being separated from the under surface of the posterior lobes of the cere- brum by the tentorium cerebelli. It is connected to the rest of the encephalic mass by means of connecting bands, called crura; of these, two ascend to the cerebrum, two descend to the medulla oblongata, and two blend together in front, formmg the pons Ararolii. The Pons Varolii is that portion of the encephalic mass which rests upon the upper part of the basilar process. It constitutes a sort of centre to the various segments above named, receiving, above, the crura from the cerebrum; at the sides, the crura from the cerebellum; and, being connected, below, with the medulla oblongata. The Medulla Oblongata extends from the lower border of the pons Varolii to the upper part of the spinal cord. It lies beneath the cerebellum, resting on the lower part of the basilar groove of the occipital bone. Weight of the Encephalon, The average weight of the brain in the adult male is 49J oz., or a little more than 3 lb. avoirdupois, that of the female 41 oz., the average difference between the two being from 5 to 6 oz. The prevailing weight of the brain in the male ranges between 46 oz. and 53 oz., and in the female, between 41 oz. and 47 oz. In the male, the maximum weight out of 278 cases Avas 65 oz., and the minimum weight 34 oz. The maximum weight of the adult female brain, out of 191 cases, was 56 oz., and the minimum weight MEDULLA OBLONGATA. 451 :!1 oz. It appears that the weight of the brain increases rapidly up to the seventh year, more slowly to between sixteen and twenty, and still more slowly to between thirty and forty, when it reaches its maximum. Beyond this period, as ao-e ad- vances and the mental faculties decline, the brain diminishes slowly in weight about an ounce for each subsequent decennial period. These results apply alike to both sexes. The size of the brain appears to bear a general relation to the intellectual capa- city of the individual. Cuvier's brain weighed rather more than 64 oz., that of the late Dr. Abercrombie 63 oz., and that of Dupuytren 62J oz. On the other hand, the brain of an idiot seldom Aveighs more than 23 oz. The human brain is heavier than that of all the lower animals excepting the elephant and whale. The brain of the former Aveighs from 81b to 101b, and that of the whale, in a specimen seventy-five feet long, weighed rather more than 51b. Medulla Oblongata. The medulla oblongata is the upper enlarged part of the spinal cord, and ex- tends from the upper border of the atlas to the lower border of the pons Varolii. It is directed obliquely downwards and backwards, its anterior surface resting on the basilar groove of the occipital bone, its posterior surface being received into the fossa between the hemispheres of the cerebellum, forming the floor of the fourth ventricle. It is pyramidal in form, its broad extremity directed up- wards, its loAver end being narrow at its point of connection with the cord. It measures an inch and a quarter in length, three quarters of an inch in breadth at its widest part, and half an inch in thickness. Its surface is marked in the median line, in front and behind, by an anterior and posterior median fissure, which are continuous with those of the spinal cord. The anterior fissure contains a fold of pia mater, and terminates below the pons in a cul-de-sac, the foramen caecum. The posterior is a deep but narrow fissure, continued upwards along the floor of the fourth ventricle, where it is finally lost. These two fissures divide the medulla into tAvo symmetrical halves, each lateral half being subdivided by minor grooves into four columns, which, from before backAvards, are named, the anterior pyramid, lateral tract and olivary body, the restiform body, the posterior pyramid. The Anterior Pyramids are two pyramidal-shaped bundles of white matter, placed one on either side of the anterior median fissure, and sepa- rated from the olivary body, Avhich is external to them, by a slight depres- sion. At the lower border of the pons they are somewhat constricted; they then become enlarged, and taper slightly as they descend, being con- tinuous below Avith the anterior co- ■ lumns of the cord. On separating the pyramids beloAv, it will be observed that the innermost fibres of the tAvo form from four to five bundles on each side, Avhich decussate with one another ; this decussation, however, is not form- ed entirely of fibres from the pyramids, but mainly from the deep portion of the lateral columns of the cord Avhich pass forwards to the surface between the diverging anterior columns. The outermost fibres do not decussate; they 237.—Medulla Oblongata and Pons Varoli Anterior Surface. 452 NERVOUS SYSTEM. are derived from the anterior columns of the cord, and are continued directly up. wards through the pons Varolii. Lateral Tract and Olivary Body. The lateral tract is continuous with the lateral column of the cord. BeloAv, it is broad, and includes that part of the medulla betAveen the anterior pyramid and restiform body ; but, above, it is pushed a little backAvards, and narroAved by the projection forwards of the olivary body. The Olivary Bodies are two prominent, oval masses, situated behind the ante- rior pyramids, from Avhich they are separated by slight grooves. They equal, in breadth, the anterior pyramids, are a little broader above than beloAv, and are about half an inch in length, being separated, above, from the pons Varolii, by a slight depression. Numerous white fibres (fibra? arciformes) are seen Avinding around the lower end of each body; sometimes crossing their surface. The Restiform Bodies are the largest columns of the medulla, and continuous, beloAv, Avith the posterior columns of the cord. They are tAvo rounded, cord-like eminences, placed betAveen the lateral tracts, in front, and the posterior pyramids, behind; from both of Avhich they are separated by slight grooves. As they ascend, they diverge from each other, assist in forming the lateral boundaries of the fourth ventricle, and then enter the corresponding hemisphere of the cerebellum, forming its inferior peduncle. The Posterior Pyramids (fasciculi graciles) are tAvo narrow, white cords, placed one on each side of the posterior median fissure, and separated from the restiform bodies by a narrow groove. They consist entirely of Avhite fibres, and are con- tinuous with the posterior median columns of the spinal cord. These bodies lie at first, in close contact. Opposite the apex Fig. 238—Posterior Surface of Medulla 0f the fourth ventricle, they form an en- largement [processus clavatus), and then, diverging, are lost in the corresponding restiform body. The upper part of the posterior pyramids forms the lateral bounda- ries of the calamus scriptorius. The Posterior surface of the Medulla Oblongata forms part of the floor of the fourth ventricle. It is of a triangular form, bounded on each side by the diverging pos- terior pyramids, and is that part of the ventricle which, from its resemblance to the point of a pen, is called the calamus scrip- torius. The divergence of these columns and the restiform bodies, opens to view the gray matter of the medulla, which is con- tinuous, below, with the gray commissure of the cord. In the middle line is seen a longitudinal furroAv, continuous with the posterior median fissure of the cord, termi- nating, below, at the point of the ventricle, in a cul-de-sac, the ventricle of Arantius, Avhich descends into the medulla for a slight extent. It is the remains of a canal, which, in the foetus, extends throughout the entire length of the cord. Structure. The columns of the cord are directly continuous with those of the medulla oblongata, below; but, higher up, both the white and gray constitu- ents are rearranged before they are continued upwards to the cerebrum and cerebellum. The Anterior Pyramid is composed of fibres derived from the anterior column of the cord of its own side, and from the lateral column of the opposite half of the cord, and is continued upwards into the cerebrum and cerebellum. The STRUCTURE OF MEDULLA OBLONGATA. 453 Fig. 239.—Transverse Section of Medulla Oblongata. JFssfcrurr rtssure cerebellar fibres form a superficial and deep layer, which pass beneath the olive to the restiform body, and spread out into the structure of the cerebellum. A deeper fasciculus incloses the olivary body, and, receiving fibres from it, enters the pons as the olivary fasciculus or fillet; but the chief mass of fibres from the pyramid, the cerebral fibres, enter the pons in their passage upAvards to the cerebrum. The anterior pyramids contain no gray matter. The Lateral Tract is continuous, be- low, with the lateral column of the cord. Its fibres pass in three different directions. The most external join the restiform body, and pass to the cerebellum. The internal, more numerous, pass forAvards, pushing aside the fibres of the anterior column, and form part of the opposite anterior pyramid. The middle fibres ascend, beneath the olivary body, to the cerebrum, passing along the back of the pons, and form, together with fibres from the resti- form body, the fasciculi teretes, in the floor of the fourth ventricle. Anterior FUsurv r-sciculi Ttrctes \0lirary Body Anterior Fyramid, Fig. 240.- -The Columns of the Medulla Oblongata, and their Connection with the Cerebrum and Cerebellum. Olivary Body. If a transverse section is made through either olivary body, it will be found to be a small ganglionic mass, deeply imbedded in the medulla, partly appearing on the surface as a smooth, olive-shaped eminence (Fig. 239). It consists, externally, of white substance; and internally, of a gray nucleus, the corpus dentatum. The gray matter is arranged in the form of a hollow capsule, open at its upper and inner part, and presenting a zigzag, or dentated outline. White fibres originate from the interior of this body, by the aperture in the posterior part of the capsule. They join with those fibres of the anterior column which ascend on the outer side, and beneath the olive, to form the olivary fasciculus, which ascends to the cerebrum. The Restiform Body is formed chiefly of fibres from the posterior column of the 454 NERVOUS SYSTEM. cord ; but it receives some from the lateral column, and a fasciculus from the anterior, and is continued upAvards, to the cerebrum and cerebellum. On enter- ing the pons, it divides into tAvo fasciculi, above the point of the fourth ventricle. The most'external one enters the cerebellum : the inner one joins the posterior pyramid, is continued up along the fourth ventricle, and, joining the fasciculi teretes, passes up to the cerebrum. Septum of the Medulla Oblongata. Above the decussation of the anterior pyramids, numerous white fibres extend, from behind forAvards, in the median line, forming a septum, Avhich subdivides the medulla into tAvo lateral halves. Some of these fibres emerge at the anterior median fissure, and form a band which curves around the loAver border of the olivary body, or passes transversely across it, and round the sides of the medulla, forming the arciform fibres of Rolando. Others appear in the floor of the fourth ventricle, issuing from the posterior median fissure, and form the Avhite striae in that situation. Gray Matter of the Medulla Oblongata. The gray matter of the medulla is a continuation of that contained in the interior of the spinal cord, besides a series of special deposits, or nuclei. In the lower part of the medulla the gray matter is arranged as in the cord, but, at the upper part, it becomes more abundant, and is disposed with less apparent regularity, becoming blended Avith all the white fibres, except the anterior pyramids. The part corresponding to the transverse gray commissure of the cord is exposed to aIcav in the floor of the medulla oblongata, by the diverg- ence of the restiform bodies and posterior pyramids, becoming blended with the ascending fibres of the lateral column, and thus forming the fasciculi teretes. The lateral crescentic portions, but especially the posterior horns, become enlarged, blend Avith the fibres of the restiform bodies, and form the tuberculo cinereo of Rolando. Special deposits of gray matter are found both in the anterior and posterior parts of the medulla ; in the former situation, forming the corpus dentatum Avithin the olivary body, and in the latter, a series of special masses, or nuclei, connected Avith the roots'of origin of the spinal accessory, vagus, glosso-pharyn- geal, and hypoglossal nerves. Pons Varolii. The pons Varolii (mesocephale, Chaussier) is the bond of union of the various segments of the encephalon, connecting the cerebrum above, the medulla oblongata below, and the cerebellum behind. It is situated above the medulla oblongata, below the crura cerebri, and betAveen the hemispheres of the cerebellum. Its under surface presents a broad transverse band of Avhite fibres, which arches like a bridge across the upper part of the medulla, extending betAveen the two hemispheres of the cerebellum. This surface projects considerably beyond the level of these parts, is of a quadrangular form, rests upon the basilar groove of the occipital bone, and is limited before and behind by very prominent margins. It presents along the middle line a longitudinal groove, wider in front than behind, which lodges the basilar artery ; numerous transverse striae are also observed on each side, which indicate the course of its superficial fibres. Its upper surface forms part of the floor of the fourth ventricle, and at each side it becomes contracted into a thick rounded cord, the crus cerebelli, which enters the substance of the cerebellum, constituting its middle peduncle. Structure. The pons Varolii consists of alternate layers of transverse and longi- tudinal fibres intermixed Avith gray matter (Fig. 240). The transverse fibres connect together the two lateral hemispheres of the cere- bellum, and constitute its great transverse commissure. They consist of a super- ficial and a deep layer. The superficial layer passes uninterruptedly across the surface of the pons, forming a uniform layer, consisting of fibres derived from the crus cerebelli on each side, which meet in the median line. The deep layer of CEREBRUM. 455 transverse fibres decussate Avith the longitudinal fibres continued up from the medulla; they also connect the hemispheres of the cerebellum. The longitudinal fibres are continued up through the pons. 1. From the ante- rior pyramidal body. 2. From the olivary body. 3. From the lateral and pos- terior columns of the cord, receiving special fibres from the gray matter of the pons itself. 1. The fibres from the anterior pyramid ascend through the pons, imbedded between tAvo layers of transverse fibres, being subdivided in their course into smaller bundles ; at the upper border of the pons they enter the crus cerebri, form- ing its fasciculated portion. 2. The olivary fasciculus divides in the pons into tAvo bundles, one of which ascends to the corpora quadrigemina; the other is continued to the cerebrum with the fibres of the lateral column. 3. The fibres from the lateral and posterior columns of the cord, with a bundle from the olivary fasciculus, are intermixed with much gray matter, and appear in the floor of the fourth ventricle as the fasciculi teretes; they ascend to the deep or cerebral part of the crus cerebri. Septum. The pons is subdivided into two lateral halves by a median septum, which extends through its posterior half. The septum consists of antero-posterior and transverse fibres. The former are derived from the floor of the fourth ven- tricle and from the transverse fibres of the pons, which bend backAvards before passing across to the opposite side. The latter are derived from the floor of the fourth ventricle, they pierce the longitudinal fibres, and are then continued across from one to the other side of the medulla, piercing the antero-posterior fibres. The two halves of the pons, in front, are connected together by transverse com- missural fibres. Cerebrum. Upper Surface. The cerebrum, in man, constitutes the largest portion of the encephalon. Its upper surface is of an ovoidal form, broader behind than in front, convex in its general outline, and divided into two lateral halves or hemispheres, right and left, by the great longitudinal fissure. This fissure extends throughout the entire length of the cerebrum in the middle line, reaching <1oavii to the base of the brain in front and behind, but interrupted in the middle by a broad transverse com- missure of white matter, the corpus callosum, which connects the two hemispheres together. This fissure lodges the falx cerebri, and indicates the original develop- ment of the brain by two lateral halves. Each hemisphere presents an outer surface, which is convex to correspond Avith the vault of the cranium ; an inner surface, flattened, and in contact with the oppo- site hemisphere, the two forming the sides of the longitudinal fissure; and an under surface or base, of more irregular form, which rests, in front, in the anterior and middle fossae at the base of the skull, and behind, upon the tentorium. Convolutions. If the pia mater is removed with the forceps, the entire surface of each hemisphere will present a number of convoluted eminences, the convolu- tions, separated from each other by depressions (sulci) of \Tarious depths. The outer surface of each convolution, as well as the sides and bottom of the sulci betAveen them, are composed of gray matter, Avhich is here called the cortical substance. The interior of each convolution is composed of white matter; white fibres also blend with the gray matter at the sides and bottom of the sulci. By this arrangement the convolutions are admirably adapted to increase the amount of gray matter Avithout occupying much additional space, and also afford a greater extent of surface for the fibres to terminate in it. On closer examination, however, the gray matter of the cortical substance is found subdivided into four layers, two of which are composed of gray and two of white substance. The most external is an outer Avhite stratum, not equally thick over all parts of the brain, being most marked on the convolutions in the longitudinal fissure and on the under part of the brain, especially on the middle lobe, near the descending horn of the lateral 456 NERVOUS SYSTEM. ventricle. Beneath the latter is a thick reddish-gray lamina, and then another thin white stratum; lastly, a thin stratum of gray matter, which lies in close contact Avith the white fibres of the hemispheres : consequently, Avhite and gray lamina? alternate Avith one another in the gray matter of the convolutions. In certain con- volutions, hoAvever, the cortical substance consists of no less than six layers, three gray and three Avhite, an additional white stratum dividing the most superficial gray one into two ; this is especially marked in those convolutions which are situ- ated near the corpus callosum. A perfect resemblance betAveen the convolutions does not exist in all brains, nor are they symmetrical on the two sides of the same brain. Occasionally the free borders or the sides of a deep convolution present a fissured or notched appear- ance. The sulci arc generally an inch in depth; they also vary in different brains, and in different parts of the same brain; they are usually deepest on the outer convex Fig. 241.—Upper Surface of the Brain, the Pia Mater having been removed. surface of the hemispheres; the deepest is situated on the inner surface of the hemisphere, on a level with the corpus callosum, and corresponds to the projection in the posterior horn of the lateral ventricle, the hippocampus minor. The number and extent of the convolutions, as well as their depth, appear to bear a close relation to the intellectual power of the individual, as is shoAvn in their increasing complexity of arrangement as we ascend from the lowest mam- malia up to man. Thus they are absent in some of the lower orders of this class, and they increase in number and extent through the higher orders. In man they BASE OF THE BRAIN. 457 present the most complex arrangement. Again, in the child at birth, before the intellectual faculties are exercised, the convolutions have a very simple arrange- ment, presenting few undulations; and the sulci between them are less deep than in the adult. In old age, when the mental faculties have diminished in activity, the convolutions become much less prominently marked. Those convolutions Avhich are the largest and most constantly present, are the convolution of the corpus callosum, the convolution of the longitudinal fissure, the supraorbital convolution, and the convolutions of the outer surface of the hemi- sphere. The Convolution of the Corpus Callosum (gyrus fornicatus) is ahvays well marked. It lies parallel Avith the upper surface of the corpus callosum, com- mencing, in front, on the under surface of the brain in front of the anterior per- forated space ; it Avinds round the curved border of the corpus callosum, and passes along its upper surface as far as its posterior extremity, where it is connected with the convolutions of the posterior lobe; it then curves downwards and forAvards, embracing the cerebral peduncle, passes into the middle lobe, forming the hippocampus major, and terminates just behind the point from Avhence it arose. The Supraorbital Convolution on the under surface of the anterior lobe is well marked. The Convolution of the Longitudinal Fissure bounds the margin of the fissure on the upper surface of the hemisphere. It commences on the under surface of the brain, at the anterior perforated spot, passes forwards along the inner margin of the anterior lobe, being here divided by a deep sulcus, in which the olfactory nerve is received; it then curves over the anterior and upper surface of the hemisphere, along the margin of the longitudinal fissure, to its posterior extremity, where it curves forAvards along the under surface of the hemisphere as far as the middle lobe. The convolutions on the outer convex surface of the hemisphere, the general direction of which is more or less oblique, are the largest and the most complicated conArolutions of the brain, frequently becoming branched like the letter YT in their course upwards and backwards towards the longitudinal fissure: these convolutions attain their greatest development in man, and are especially characteristic of the human brain. They are seldom symmetrical on the two sides. Cerebrum. Under Surface or Base. The under surface of each hemisphere presents a subdivision, as already men- tioned, into three lobes, named, from their position, anterior, middle, and pos- terior. The anterior lobe, of a triangular form, with its apex backAvards, is somewhat concave, and rests upon the convex surface of the roof of the orbit, being sepa- rated from the middle lobe by the fissure of Sylvius. The middle lobe, wliich is more prominent, is received into the middle fossa of the base of the skull. The posterior lobe rests upon the tentorium, its extent forAvards being limited by the anterior margin of the cerebellum. The various objects exposed to view on the under surface of the cerebrum in the middle line are here arranged in the order in which they are met Avith from before backAvards. Longitudinal fissure. Tuber cincrcum. Corpus callosum and its peduncles. Infundibulum. Lamina cinerea. Pituitary body. Olfactory nerve. Corpora albicantia. Fissure of Sylvius. Posterior perforated space. Anterior perforated space. Crura cerebri. Optic commissure. The Longitudinal Fissure separates the two hemispheres from one another; it 458 NERVOUS SYSTEM. divides the two anterior lobes in front; and on raising the cerebellum and pons, it Avill be seen completely separating the tAvo posterior lobes, the intermediate por- tion of the fissure being arrested by the great transverse band of white matter the corpus callosum. Of these two portions of the longitudinal fissure, that which separates the posterior lobes is the longest. In the fissure betAveen the tAvo ante- rior lobes, the anterior cerebral arteries may be seen ascending to the corpus callosum; and at the back part of this portion of the fissure, the anterior curved portion of the corpus callosum descends to the base of the brain. Fig. 242.—Base of the Brain. The Corpus Callosum terminates at the base of the brain by a concave margin, which is connected with the tuber cinereum through the intervention of a thin layer of gray substance, the lamina cinerea. This may be exposed by gently raising and drawing back the optic commissure. A broad white band may be observed on each side, passing from the under surface of the corpus callosum in front, backAvards and outwards, to the commencement of the fissure of Sylvius; these bands are called the peduncles of the corpus callosum. Laterally, the corpus callosum extends into the anterior lobe. The Lamina Cinerea is a thin layer of gray substance, extending backwards from the termination of the corpus callosum above the optic commissure to the tuber cmereum; it is continuous on either side with the gray matter of the ante- BASE OF THE BRAIN. 459 rior perforated space, and forms the anterior part of the inferior boundary of the third ventricle. The Olfactory Nerve, with its bulb, is seen on either side of the longitudinal fissure, upon the under surface of each anterior lobe. The Fissure of Sylvius separates the anterior and middle lobes, and lodges the middle cerebral artery. At its entrance is seen a point of medullary substance, corresponding to a subjacent band of white fibres, connecting the anterior and middle lobes, and called the fasciculus unciformis ; on folloAving this fissure out- wards, it divides into tAvo branches, which inclose a triangular-shaped prominent cluster of isolated convolutions, the island of Reil. These convolutions, from being covered in by the sides of the fissure, are called the gyri operti. The Anterior Perforated Space is situated at the inner side of the fissure of Sylvius. It is of a triangular shape, bounded in front by the convolution of the anterior lobe and roots of the olfactory nerve; behind, by the optic tract; ex- ternally, by the middle lobe and commencement of the fissure of Sylvius; internally, it is continuous witli the lamina cinerea, and crossed by the peduncle of the corpus callosum. It is of a grayish color, and corresponds to the under surface of the corpus striatum, a large mass of gray matter, situated in the interior of the brain; it has received its name from being perforated by numerous minute apertures for the transmission of small straight vessels into the substance of the corpus striatum. The Optic Commissure is situated in the middle line, immediately behind the lamina cinerea. It is the point of junction betAveen the two optic nerves. Immediately behind the diverging optic tracts, and betAveen them and the peduncles of the cerebrum (crura cerebri), is a lozenge-shaped interval, the inter- peduncular space, in Avhich are found the folloAving parts, arranged in the folloAving order from before backwards : the tuber cinereum, infundibulum, pituitary body, corpora albicantia, and the posterior perforated space. The Tuber Cinereum is an eminence of gray substance, situated between the optic tracts and the corpora albicantia ; it is connected with the surrounding parts of the cerebrum, forms part of the floor of the third ventricle, and is continuous ivith the gray substance in that cavity. From the middle of its under surface, a conical tubular process of gray matter, about tAvo lines in length, is continued dowmvards and forwards to be attached to the posterior lobe of the pituitary body ; this is the infundibulum. Its canal, funnel-shaped in form, communicates with that of the third ventricle. The Pituitary Body is a small reddish-gray vascular mass, weighing from five to ten grains, and of an oval form, situated in the sella Turcica, in connection Avith which it is retained by the dura mater, which forms the inner Avail of the cavernous sinus. It is very vascular, and consists of tAvo lobes, separated from one another by a fibrous lamina, Of these, the anterior is the larger, of an oblong form, and somewhat concave behind, where-it receives the posterior lobe, which is round. The anterior lobe consists externally of firm yellowish-gray substance, and inter- nally of a soft pulpy substance of a yellowish-Avhite color. The posterior lobe is darker than the anterior. In the foetus it is larger proportionally than in the adult, and contains a cavity which communicates through the infundibulum Avith the third ventricle. In the adult it is firmer and more solid, and seldom contains any cavity. Its structure, especially the anterior lobe, is similar to that of the ductless glands. The Corpora Albicantia are tAvo small round white masses, each about the size of a pea, placed side by side immediately behind the tuber cinereum. They arc formed by the anterior crura of the fornix, hence called the bulbs of the fornix, which, after descending to the base of the brain, are folded upon them- selves, before passing upwards to the thalami optici. They are composed exter- nally of white substance, and internally of gray matter ; the gray matter of the two being connected by a transverse commissure of the same material. At an early period of fcetal life they are blended together into one large mass, but become separated about the seventh month. 460 NERVOUS SYSTEM. The Posterior Perforated Space (Pons Tarini) corresponds to a Avhitish-o---av substance, placed betAveen the corpora albicantia in front, the pons Varolii behind and the crura cerebri on either side. It forms the back part of the floor of the third ventricle, and is perforated by numerous small orifices for the passage of bloodvessels to the thalami optici. The Crura Cerebri (Peduncles of the Cerebrum) are two thick cylindrical bundles of Avhite matter, Avhich emerge from the anterior border of the pons, and diverge as they pass forAvards and outAvards to enter the under part of either hemisphere. Each crus is about three-quarters of an inch in length, and some- Avhat broader in front than behind. They are marked upon their surface with longitudinal striae, and each is crossed, just before entering the hemisphere, by a flattened Avhite band, the optic tract, Avhich is adherent by its upper border to the peduncle. In its interior is contained a mass of dark gray matter, called locus niger. The third nerves may be seen emerging from the inner side of either crus ; and the fourth nerve winding around its outer side from above. Each crus consists of a superficial and deep layer of longitudinal Avhite fibres continued upwards from the pons, separated by a mass of gray matter, the locus niger. The Superficial Longitudinal Fibres are continued upAvards, from the anterior pyramids to the cerebrum. They consist of coarse fasciculi, which form the free part of the crus, and have received the name of the fasciculated portion of the peduncle, or crust. The Deep Layer of Longitudinal Fibres is continued upwards, to the cere- brum, from the lateral and posterior columns of the medulla, and from the olivary fasciculus, these fibres consisting of some derived from the same, and others from the opposite lateral tract of the medulla. More deeply, is a layer of finer fibres, mixed with gray matter, derived from the cerebellum, blended Avith the former. The cerebral surface of the crus cerebri is formed of these fibres, and is named the tegmentum. The Locus Niger is a mass of gray matter, situated betAveen the superficial and deep layers of fibres above described. It is placed nearer the inner than the outer side of this body. The posterior lobes of the cerebrum are concealed from A-ieAv by the upper surface of the cerebellum, and pons Varolii. When these parts are removed, the two hemispheres are seen to be separated by the great longitudinal fissure, this fissure being arrested, in front, by the posterior rounded border of the corpus callosum. General Arrangement of the Parts composing the Cerebrum. As the peduncles of the cerebrum enter the hemispheres, they diverge from one.another, so as to leave an interval between them, the interpeduncular space. As they ascend, the component fibres of each pass through two large masses of gray matter called the ganglia of the brain, the thalami optici, and corpora striata, which project as rounded eminences from the upper and inner side of each peduncle. The hemispheres are connected together, above these masses, by the great transverse commissure, the corpus callosum, and the interval left between its under surface, the upper surface of the ganglia, and the parts closing the interpeduncular space, forms the general ventricular cavity. The upper part of this cavity is subdivided into two, by a vertical septum, the septum lucidum; and thus the two lateral ventricles are formed. The lower part of this cavity forms the third ventricle, which communicates with the lateral ventricles, above, and with the fourth ventricle, behind. The fifth ventricle is the interval left between the two layers composing the septum lucidum. Intkrior of the Cerebrum. If the upcr part of either hemisphere is removed with a scalpel, about half an CORPUS CALLOSUM. 461 inch above the level of the corpus callosum, its internal white matter will be exposed. It is an oval-shaped centre, of white substance, surrounded on all sides by a narroAv convoluted margin of gray matter, which presents an equal thickness in nearly every part. This white, central mass, has been called the centrum ovale minus. Its surface is studded with numerous minute red dots (puncta vasculosa), produced by the escape of blood from divided bloodvessels. In inflammation, or great congestion of the brain, these are very numerous, and of a dark color. If the remaining portion of the hemispheres are slightly separated from one another, a broad band of white substance will be observed connecting them, at the bottom of the longitudinal fissure : this is the corpus callosum. The margins of the hemispheres, Avhich overlap this portion of the brain, are called the labia cerebri. It is a part of the convolution of the corpus callosum (gyrus for nic at us), already described; and the space between it and the upper surface of the corpus callosum, has been termed the ventricle of the corpus callosum. The hemispheres should noAv be sliced off, to a level with the corpus callosum, when the white substance of that structure will be seen connecting together both hemispheres. The large expanse of medullary matter noAV exposed, surrounded by the convoluted margin of gray substance, is called the centrum ovale majus of Yieussens. Fig. 243.—Section of the Brain. Made on a Level with the Corpus Callosum. The Corpus Callosum is a thick stratum of transverse fibres, exposed at the bottom of the longitudinal fissure. It connects the two hemispheres of the brain, forming their great transverse commissure; and forms the roof of a space in the interior of each hemisphere, the lateral ventricle. It is about four inches in length, extending to A\lthin an inch and a half of the anterior, and to within two 462 NERVOUS SYSTEM. inches and a half of the posterior part of the brain. It is somcAvhat broader behind than in front, and it is thicker at either end than in its central part, being thickest behind. It presents a somewhat arched form, from before backwards terminating anteriorly in a rounded border, Avhich curves downAvards and back- Avards, betAveen the anterior lobes to the base of the brain. In its course it forms a distinct bend, named the knee or genu, and the reflected portion named the beak (rostrum), becoming gradually narroAver, is attached to the anterior cerebral lobe, and is connected, through the lamina cinerea, with the optic commissure. The reflected portion of the corpus callosum gives off, near its termination two bundles of Avhite substance, Avhich, diverging from one another, pass backAvards across the anterior perforated space, to the entrance of the fissure of Sylvius! They are called the peduncles of the corpus callosum. Posteriorly, the corpus callosum forms a thick, rounded fold, which is free for a little distance, as it curves forAvards, and is then continuous with the fornix. On its upper surface its fibrous structure is very apparent to the naked eye, being collected into coarse', transverse bundles. Along the middle line, is a linear depression, the raphe, bounded laterally by two or more slightly elevated longitudinal bands, called the stria longitudinales, or nerves of Lancisi; and, still more externally, other longitudinal striae are seen, beneath the convolution, which rests on the corpus callosum. These are the striae longitudinales laterales. The under surface of the corpus callosum Fig. 244.—The Lateral Ventricles of the Brain. tinuous behind with the fornix, being separated from it in front by the sep- ucidum, which forms a vertical partition between the two ventricles. On LATERAL VENTRICLES. 463 either side, the fibres of the corpus callosum penetrate into the substance of the hemispheres, and connect together the anterior, middle, and part of the posterior lobes. It is the increased aggregation of fibres derived from the anterior and posterior lobes, which explains the great thickness of the tAvo extremities of this commissure. An incision should now be made through the corpus callosum, on either side of the raphe, when two large irregular cavities will be exposed, which extend throughout the entire length of each hemisphere. These are the lateral ventricles. The Lateral Ventricles are serous cavities, formed by the upper part of the general ventricular space in the interior of the brain. They are lined by a thin diaphanous lining membrane, covered Avith ciliated epithelium, and moistened by a serous fluid, Avhich is sometimes, even in health, secreted in considerable quantity. These cavities are tAvo in number, one in each hemisphere, and they are sepa- rated from each other by a vertical septum,—the septum lucidum. Each lateral ventricle consists of a central cavity, or body, and three smaller cavities, or cornu, Avhich extend from it in different directions. The anterior cornu curves forAvards and outAvards, into the substance of the anterior lobe. The posterior cornu, called the digital cavity, curves backAvards into the posterior lobe. The middle cornu descends into the middle lobe. The Central Cavity, or body of the lateral ventricle, is triangular in form. It is bounded, above, by the under surface of the corpus callosum, Avhich forms the roof of the cavity. Internally, is a vertical partition, the septum lucidum, Avhich separates it from the opposite ventricle, and connects the under surface of the corpus callosum with the fornix. Its floor is formed by the folloAving parts, enumerated in their order of position, from before backAvards, the corpus striatum, taenia semicircularis, thalamus opticus, choroid plexus, corpus fimbriatum, and fornix. The Anterior Cornu, is triangular in form, passing outAvards into the anterior lohe, and curving round the anterior extremity of the corpus striatum. It is bounded, above and in front, by the corpus callosum; behind, by the corpus striatum. The Posterior Cornu, ox digital cavity, curves backAvards into the substance of the posterior lobe, its direction being backAvards and outwards, and then inAvards. On its floor is seen a longitudinal eminence, Avhich corresponds Avith a deep sulcus betAveen two convolutions: this is called the hippocamjms minor. BetAveen the middle and posterior horns, a smooth eminence is observed, Avhich varies con- siderably in size in different subjects. It is called the eminentia collateralis. The Corpus Striatum (superior ganglion of the cerebrum), has received its name from the striated appearance Avhich its section presents, from Avhite fibres dhrerging through its substance. The intraventricular portion is a large pear- shaped mass, of a gray color externally; its broad extremity is directed forAvards, into the forepart of the body, and anterior cornu of the lateral ventricle; its narroAv end is directed outAvards and backAvards, being separated from its felloAV by the thalami optici; it is covered by the serous lining of the cavity, and crossed by some veins of considerable size. The extraventricular portion is imbedded in the Avhite substance of the hemisphere. The Teenia Semicircularis is a narroAv, Avhitish, semitransparent band of medullary substance, situated in the depression betAveen the corpus striatum and thalamus opticus. Anteriorly, it descends in connection with the anterior pillar of the fornix; behind, it is continued into the descending horn of the ventricle, Avhere it becomes lost. Its surface, especially at its forepart, is transparent, and dense in structure, and was called by Tarinus the horny band. It consists of longitudinal Avhite fibres, the deepest of Avhich run between the corpus striatum and thalamus opticus. Beneath it is a large vein (vena corporis striati), which receives numerous smaller veins from the surface of the corpus striatum, and thalamus opticus, and terminates in the venae Galeni. 464 NERVOUS SYSTEM. The Choroid Plexus is a highly vascular, fringe-like membrane, occupying the margin of the fold of pia mater (velum interpositum), in the interior of the brain. It extends, in a curved direction, across the floor of the lateral ventricle. In front Avhere it is small and tapering, it communicates Avith the choroid plexus of the opposite side, through a large oval aperture, the foramen of Monro. Poste- riorly, it descends into the middle horn of the lateral ventricle, Avhere it joins with the pia mater through the transverse fissure. In structure, it consists of minute and highly vascular villous processes, the villi being covered by a single layer of epithelium, composed of large, round corpuscles, containing, besides a central nucleus, a bright yelloAV spot. The arteries of the choroid plexus enter the ven- tricle at the descending cornu, and, after ramifying through its substance, send branches into the substance of the brain. The veins of the choroid plexuses ter- minate in the venae Galeni. The Corpus Fimbriatum, or Taenia Hippocampi, is a narroAv, white, tape-like band, situated immediately behind the choroid plexus. It is the lateral edge of the posterior pillar of the fornix, and is attached along the inner border of the hippocampus major as it descends into the middle horn of the lateral ventricle. It may be traced as far as the pes hippocampi. Fig. 245.—The Fornix, Velum Interpositum, and Middle or Descending Cornu of the Lateral Ventricle. The Thalami Optici and Fornix will be described Avhen more completely ex- posed, in a later stage of the dissection of the brain. LATERAL VENTRICLE. 465 The middle cornu should now be exposed, throughout its entire extent, by introducing the little finger gently into it, and cutting through the hemisphere, between it and the surface, in the direction of the cavity. The Middle, or Descending Cornu, the largest of the three, traverses the middle lobe of the brain, forming in its course a remarkable curve round the back of the optic thalamus. It passes, at first, backAvards, outAvards, and downwards, and then curves around the crus cerebri, forAvards and inAvards, nearly to the point of the middle lobe, close to the fissure of Sylvius. Its superior boundary is formed by the medullary substance of the middle lobe, and the under surface of the thalamus opticus. Its inferior boundary presents for examination the following parts: the hippocampus major, pes hippocampi, pes accessorius, corpus fimbriatum, choroid plexus, fascia dentata, transverse fissure. The Hijrpocampus Major, or Cornu Ammonis, so called from its resemblance to a ram's horn, is a Avhite eminence, of a curved elongate form, extending along the entire length of the floor of the middle horn of the lateral ventricle. At its lower extremity it becomes enlarged, and presents a number of rounded elevations Avith intervening depressions, Avhich, from presenting some resemblance to the claAV of an animal, is called the pes hippocampi. If a transverse section is made through the hippocampus major, it will be seen that this eminence is the inner surface of the convolution of the corpus callosum, doubled upon itself like a horn, the white convex portion projecting into the cavity of the ventricle ; the gray portion being on the surface of the cerebrum, the edge of Avhich, slightly indented, forms the fascia dentata. The Avhite matter of the hippocampus major is continuous through the corpus fimbriatum Avith the fornix and corpus callosum. The Pes Accessorius, or Eminentia Collatcralis, has been already mentioned, as a white eminence, varying in size, placed betAveen the hippocampus major and minor, at the junction of the posterior Avith the descending cornu. Like the hippocampi, it is formed by white matter corresponding to one of the sulci, between tAvo convolutions protruding into the cavity of the ventricle. The Corpus Fimbriatum, or Taenia Hippocampi, is a narrow, tape-like band, attached along the inner concave border of the hippocampus major, and reaching doAvn as far as the pes hippocampi. It is a continuation of the posterior pillar of the fornix, prolonged from the central cavity of the lateral ventricle. Fascia Dentata. On separating the inner border of the corpus fimbriatum from the choroid plexus, and raising the edge of the former, a serrated band of gray substance, the edge of the gray substance of the middle lobe, will be seen beneath it: this is the fascia dentata. Correctly speaking, it is placed external to the cavity of the descending cornu. The Transverse Fissure is seen on separating the corpus fimbriatum from the thalamus opticus. It is situated beneath the fornix, extending from the middle line behind, dowmvards on either side, to the end of the descending cornu, being bounded on one side by the fornix and the hemisphere, and on the other by the thalamus opticus. Through this fissure the pia mater passes from the exterior of the brain into the ventricles, to form the choroid plexuses. AVhere the pia mater projects into the lateral ventricle, beneath the edge of the fornix, it is covered by a prolongation of the lining membrane, which excludes it from the cavity. The Septum Lucidum forms the internal boundary of the lateral ventricle. It is a thin, semi-transparent septum, attached, above, to the under surface of the corpus callosum; beloAV, to the anterior part of the fornix; and, in front of this, to the prolonged portion of the corpus callosum. It is triangular in form, broad in front, and narroAv behind, its surfaces looking towards the cavities of the ventricles. The septum consists of two laminae, separated by a narrow interval, the fifth ventricle. Each lamina consists of an internal layer of white substance, covered by the lining membrane of the fifth ventricle; and an outer layer of gray matter, covered by the lining membrane of the lateral ventricle. The cavity of the ventricle is lined by a serous membrane, covered with epithelium, and contains fluid. In the 32 466 NERVOUS SYSTEM. foetus, and in some animals, this cavity communicates, below, Avith the third ventricle; but in the adult, it forms a separate cavity. In cases of serous effusion into the ventricles, the septum is often found softened and partially broken doAvn. The fifth ventricle may be exposed by cutting through the septum, and attached portion of the corpus callosum, with the scissors ; after examining which, the corpus callosum should be cut across, towards its anterior part, and the two portions carefully dissected, the one for- wards, the other backwards, when the fornix will be exposed. The Fornix is a longitudinal lamella of fibrous matter, situated beneath the corpus callosum, with which it is continuous behind, but separated from it in front by the septum lucidum. It may be divided along the middle line into two symmetrical halves, one for either hemisphere. These two portions are joined together in the middle line, where they form the body, but are separated from one another in front and behind; in front, forming the anterior crura, and behind, the posterior crura. The body of the fornix is triangular in form; narrow in front, broad behind. Its upper surface is connected, in the median line, to the septum lucidum in front, and the corpus callosum behind. Its inner surface rests upon the velum interpo- situm, which separates it from the third ventricle, and the inner portion of the optic thalami. Its lateral edges form, on each side, part of the floor of the lateral ventricles, and are in contact Avith the choroid plexuses. The anterior crura arch downwards towards the base of the brain, separated from each other by a narrow interval. They are composed of white fibres, which descend through a quantity of gray matter in the lateral walls of the third ven- tricle, and are placed immediately behind the anterior commissure. At the base of the brain, the Avhite fibres of each crus form a sudden curve upon themselves, spread out and form the outer part of the corresponding corpus albicans, from Avhich point they may be traced upwards into the substance of the corresponding thalamus opticus. The anterior crura of the fornix are connected in their course with the optic commissure, the Avhite fibres covering the optic thalamus, the peduncle of the pineal gland, and the superficial fibres of the taenia semicir- cularis. The posterior crura, at their commencement, are intimately connected by their upper surfaces with the corpus callosum ; diverging from one another, they pass downwards into the descending horn of the lateral ventricle, being continuous with the concave border of the hippocampus major. The lateral thin edges of the posterior crura have received the name corpus fimbriatum, already described. On the under surface of the fornix, toAvards its posterior part, between the diverging posterior crura, may be seen some transverse lines, and others longitudinal or oblique. This appearance has been termed the lyra, from the fancied resemblance it bears to the strings of a harp. BetAveen the anterior pillars of the fornix and the anterior extremities of the thalami optici, an oval aperture is seen on each side, the foramen of Monro. The two openings descend towards the middle line, and, joining together, lead into the upper part of the third ventricle. These openings form a transverse communica- tion betAveen the lateral ventricles, and beloAV with the third ventricle. Divide the fornix across anteriorly, and reflect the two portions, the one forwards, the other backwards, when the velum interpositum will be exposed. The Velum Interpositum is a vascular membrane, reflected from the pia mater into the interior of the brain through the transverse fissure, passing beneath the posterior rounded border of the corpus callosum and fornix, and above the corpora quadrigemina, pineal gland, and. optic thalami. It is of a triangular form, and separates the under surface of the body of the fornix from the cavity of the third ventricle. Its posterior border forms an almost complete investment for the pineal gland. Its anterior extremity, or apex, is bifid; each bifurcation being continued into the corresponding lateral ventricle, behind the anterior crura of the fornix, THALAMI OPTICI. 467 forming the anterior extremity of the choroid plexus. On its under surface are two vascular fringes, which diverge from each other behind, and project into the cavity of the third ventricle. These are the choroid plexuses of the third ven- tricle, lo its lateral margins are connected the choroid plexuses of the lateral ventricles. Ihe arteries of the velum interpositum enter from behind, beneath the corpus callosum. Its veins, the venae Galeni, two in number, run along its under surface; they are formed by the venae corporis striati and the vena3 plexfis choroidis: the veme Galeni unite posteriorly into a single trunk, which terminates m the straight sinus. The velum interpositum should now be ^ The velum interpositum should now be removed. This must be effected carefully esne dally at its posterior part where it invests the pineal gland; the thalami optici will then b. exposed with the cavity of the third ventricle beween them (Fig. 246). be Fig. 246.—The Third and Fourth Ventricles. tAvo large The Thalami Optici (Superficial Ganglia of the Cerebrum) oblong masses, placed betAveen the diverging portions of the corpora striata; they are of a white color superficially, internally they are composed of white fibres intermixed with gray matter. Each thalamus rests upon its corresponding crus cerebri, which it embraces. Externally, it is bounded by the corpus striatum and taenia semicircularis, and is continuous with the hemisphere. Internally, it forms the lateral boundary of the third ventricle ; and running along its upper border is seen the peduncle of the pineal gland. Its upper surface is free, being partly seen in the lateral ventricle ; it is partly covered by the fornix and marked in 468 NERVOUS SYSTEM. front by an eminence, the anterior tubercle. Its under surface forms the roof of the descending cornu of the lateral ventricle ; into it the crus cerebri passes. Its posterior and inferior part, Avhich projects into the descending horn of the lateral ventricle, presents tAvo small round eminences, the internal and external geniculate bodies. Its anterior extremity, Avhich is narrow, forms the posterior boundary of the foramen of Monro. The Third Ventricle is the narrow oblong fissure placed between the thalami optici,-and extending to the base of the brain. It is bounded above by the under surface of the velum interpositum, from Avhich are suspended the choroid plexuses of the third ventricle, and laterally by two Avhite tracts, one on either side, the peduncles of the pineal gland. Its floor, somewhat oblique in its direction, is formed, from before backAvards, by the parts wliich close the interpeduncular space, viz., the lamina cinerea, the tuber cinereum and infundibulum, the corpora albicantia, and the locus perforatus ; its sides, by the optic thalami; in front, by the anterior crura of the fornix and part of the anterior commissure ; behind, by the posterior commissure and the iter a tertio ad quartum ventriculum. The cavity of the third ventricle is crossed by three commissures, named, from their position, anterior, middle, and posterior. The Anterior Commissure is a rounded cord of white fibres, placed in front of the anterior crura of the fornix. It perforates the corpus striatum on either side, and spreads out into the substance of the hemispheres, over the roof of the de- scending horn of the lateral ventricle. The Middle or Soft Commissure consists almost entirely of gray matter. It connects together the thalami optici, and is continuous Avith the gray matter lining the anterior part of the third ventricle. The Posterior Commissure, smaller than the anterior, is a flattened Avhite band of fibres, connecting together the two thalami optici posteriorly. It bounds the third ventricle posteriorly, and is placed in front of and beneath the pineal gland, above the opening leading to the fourth ventricle. The third ventricle has four openings connected Avith it. In front are two oval apertures, one on either side, the foramina of Monro, through Avhich the third communicates Avith the lateral ventricles. Behind, is a third opening leading into the fourth ventricle by a canal, the aqueduct of Sylvius, or iter a tertio ad quartum ventriculum. The fourth, situated in the anterior part of the floor of the ven- tricle, is a deep pit, which leads downAvards to the funnel-shaped cavity of the infundibulum, the iter ad infundibulum. The lining membrane of the lateral ventricles is continued through the foramina of Monro into the third ventricle, and extends along the iter a tertio into the fourth ventricle; at the bottom of the iter ad infundibulum it ends in a cul-de-sac. Gray Matter of the Third Ventricle. A layer of gray matter covers the greater part of the surface of the third ventricle. In the floor of this caAuty it exists in great abundance, and is prolonged upAvards on the sides of the thalami, extending across the cavity as the soft commissure ; beloAv, it enters into the corpora albi- cantia, surrounds in part the anterior pillars of the fornix, and ascends on the sides of the septum lucidum. Behind the third ventricle, and in front of the cerebellum, are the corpora quadrigemina, and resting upon these the pineal gland. The Pineal Gland (Conarium), so named from its peculiar shape (pinus, the fruit of the fir), is a small reddish-gray body, conical in form, placed immediately behind the posterior commissure, and between the nates, upon Avhich it rests. It is retained in its position by a duplicature of pia mater, derived from the under surface of the velum interpositum, which almost completely invests it. The pineal gland is about four lines in length, and from tAvo to three in width at its base, and is said to be larger in the child than in the adult, and in the female than in the male. Its base is connected Avith the cerebrum by some transverse commissural fibres derived from the posterior commissure, and by four slender peduncles, formed of medullary fibres. Of these the two superior pass forwards upon the upper and CORPORA QUADRIGEMINA; VALVE OF VIEUSSENS. 469 inner margin of the optic thalami, to the anterior crura of the fornix, with which they become blended. The inferior peduncles pass vertically downwards from the base of the pineal body, along the back part of the inner surface of the thalami, and are only seen on a longitudinal vertical section through the gland. The pineal gland is very vascular, and consists chiefly of gray matter, with a few medullary fibres. In hs base is a small cavity, said by some to communicate with that of the third ventricle. It contains a transparent viscid fluid, and occasionally a quantity of sabulous matter, which forms the acervulus cerebri; this is composed of phosphate and carbonate of lime, phosphate of magnesia and ammonia, with a little animal matter. These concretions are almost constant in their existence, and are found at all periods of life. When this body is solid, the sabulous matter is found upon its surface, and occasionally upon its peduncles. On the removal of the pineal body and adjacent portion of the pia mater, the corpora qua- drigemina are exposed. The Corpora or Tubcrcula Quadrigemina (optic lobes) are four rounded emi- nences placed in pairs, two in front, two behind, and separated from one another by a crucial depression. They are situated immediately behind the third ventricle and posterior commissure, beneath the posterior border of the corpus callosum, and above the iter a tertio ad quartum ventriculum. The anterior pair, the nates, are the larger, oblong from before backwards, and of a gray color. The posterior pair, the testes, are hemispherical in form, and lighter in color than the preceding. They are connected on each side with the thalamus opticus and commencement of the optic tracts, by means of tAvo Avhite prominent bands, termed brachia. Those connecting the nates Avith the thalamus, the brachia anteriora, are the larger, and pass obliquely outwards. Those connecting the testes with the thalamus, are called the brachia posterior a. Both pairs, in the adult, are quite solid, being composed of white matter externally, and gray matter within. These bodies are larger in the lower animals than in man. In fishes, reptiles, and birds, they are only two in number, and called the optic lobes, from their connection Avith the optic nerves; and are hollow in their interior ; but in mammalia they are four in number as in man, and quite solid. In the human foetus they are developed at a very early period, and form a large proportion of the cerebral mass; at first they are only two in number, as in the lower mammalia, and holloAV in their interior. These bodies, from below, receive white fibres from the olivary fasciculus or fillet; they are also connected with the cerebellum, by means of a large white cord on each side, the processus ad testes, or superior peduncles of the cerebellum ; from the corpora quadrigemina, these tracts pass upAvards to the thalami. The Valve of Vieussens is a thin translucent lamina of medullary substance, stretched between the two processus e cerebello ad testes ; it covers in the canal leading from the third to the fourth ventricle, forming part of the roof of the lat- ter cavity. It is narrow in front, where it is connected with the testes ; and broader behind, at its connection with the vermiform process of the cerebellum. A slight elevated ridge, the fraenulum, descends upon the upper part of the valve from the corpora quadrigemina, and on either side of it may be seen the fibres of origin of the fourth nerve. Its lower half is covered by a thin transversely-grooved lobule of gray matter prolonged from the anterior border of the cerebellum; this is called the linguetta laminosa. The Corpora Geniculata are two small flattened oblong masses, placed on the outer side of the corpora quadrigemina, and on the under and back part of each optic thalamus, and are named from their position, corpus geniculatum externum and internum. They are placed one on the outer and one on the inner side of each optic tract. In this situation, the optic tract may be seen dividing into two bands, one of Avhich is connected Avith the external geniculate body and nates, the other being connected with the internal geniculate body and testis. Structure of the Cerebrum. The white matter of each hemisphere consists of three kinds of fibres. 1. Diverging or peduncular fibres, Avhich connect the hemi- 470 NERVOUS SYSTEM. sphere with the cord and medulla oblongata. 2. Transverse commissural fibres, which connect together the tAvo hemispheres. 3. Longitudinal commissural fibres, Avhich connect distant parts of the same hemisphere. The diverging or peduncular fibres consist of a main body and of certain acces- sory fibres. The main body originate in the columns of the cord and medulla oblongata, and enter the cerebrum through the crus cerebri, Avhere they are arranged in two bundles, separated by the locus niger. Those fibres Avhich form the inferior or fasciculated portion of the crus are derived from the pyramid, and ascending, pass mainly through the centre of the striated body ; those on the oppo- site surface of the crus, wliich form the tegmentum, are derived from the posterior pyramid and fasciculi teretes ; ascending, they pass, some through the under part of the thalamus, and others through both thalamus and corpus striatum, decussating in these bodies Avith each other and Avith the fibres of the corpus callosum. The optic thalami also receive accessory fibres from the processus ad testes, the olivary fasciculus, the corpora quadrigemina, and corpora geniculate. Some of. the diverging fibres end in the cerebral ganglia, Avhilst others pass through and receive additional fibres from them, and, as they emerge, radiate into the anterior, middle, and posterior lobes of the hemisphere, decussating again with the fibres of the corpus callosum, before passing to the convolutions. The transverse commissural fibres connect together the tAvo hemispheres across the middle line. They are formed by the corpus callosum and the anterior and posterior commissures. The longitudinal commissural fibres connect together distant parts of the same hemisphere, the fibres being disposed in a longitudinal direction. They form the fornix, the taenia semicircularis, and peduncles of the pineal gland, the striae longi- tudinales, the fibres of the gyrus fornicatus, and the fasciculus uncinatus. The Cerebellum. The cerebellum or little brain is that portion of the encephalon Avhich is con- tained in the inferior occipital fossae. It is situated beneath the posterior lobes of the cerebrum, from which it is separated by the tentorium. Its average weight in the male is 5oz. 4drs. It attains its maximum Aveight between the twenty-fifth and fortieth years ; its increase in weight after the fourteenth year being relatively greater in the female than in the male. The proportion between the cerebellum and cerebrum is, in the male, as 1 to 8|, and in the female, as 1 to 8|. In the infant it is proportionally much smaller than in the adult, the relation between them being, according to Chaussier, betAveen 1 to 13 and 1 to 26 ; by Cruveilhier it was found to be 1 to 20. In form the cerebellum is oblong, flattened from above downwards, its greatest diameter being from side to side. It measures from three and a half to four inches transversely, from two to two and a half inches from before backAvards, being about two inches thick in the centre, and about six lines at its circumference, the thinnest part. It consists of gray and Avhite matter, the former, darker than that of the cerebrum, occupies the surface; the latter, the interior. The surface of the cerebellum is not convoluted like the cerebrum, but traversed by numerous curved furrows like sulci, which vary in depth at different parts, and correspond to the intervals betAveen the laminae of which its exterior is composed. Its upper surface (Fig. 247) is somewhat elevated in the median line, and depressed towards its circumference ; it consists of tAvo lateral hemispheres, connected together by an elevated median portion or lobe, the superior vermiform process. The median lobe is the fundamental part, and in some animals, as fishes and reptiles, the only part which exists, the hemispheres being additions, and attaining their maximum in man. The hemispheres are separated in front by a deep notch, the incisura cerebelli anterior, Avhich encircles the corpora quadrigemina behind; they are also separated by a similar notch behind, the incisura cerebelli posterior, in which is received the upper part of the falx cerebelli. The superior vermiform process, or upper part of the median lobe of the cerebellum, extends from the notch CEREBELLUM. 471 on the anterior to that on the posterior border. It is divided into three lobes: the lobulus centralis, a small lobe, situated in the incisura anterior ; the monticulus cerebelli, the central projecting part of the process; and the commissura simplex, a small lobe near the incisura posterior. Fig. 247.—Upper Surface of the Cerebellum. The under surface of the cerebellum (Fig. 248) is subdivided into two Avell-marked convex lateral hemispheres by a depression, the A'alley, which extends from before backwards in the middle line. The lateral hemispheres are lodged in the inferior occipital fossae ; the median depression, or valley, receives the back part of the medulla oblongata, is broader in the centre than at either extremity, and has, pro- jecting from its floor, part of the median lobe of the cerebellum, called the inferior vermiform process. The parts entering into the composition of this body are, Fig. 248.—Under Surface of the Cerebellum. from behind forwards, the commissura brevis, situated in the incisura posterior; in front of this, a laminated conical projection, the pyramid; more anterior, a larger eminence, the uvula ; placed between the two rounded lobes Avhich occupy the sides of the valley, the amygdalae ; and connected with them by a commissure of gray matter, indented on the surface, and called the furrowed band. In front of the uvula is the nodulus; it is the anterior pointed termination of the inferior 472 NERVOUS SYSTEM. vermiform process, and projects into the cavity of the fourth ventricle; it has been named by Malacarne the laminated tubercle. On each side of the nodule is a thin layer of Avhite substance, attached externally to the flocculus, and internally to the nodule, and to a corresponding part on the opposite side ; they form to- gether the posterior medullary velum, or commissure of the flocculus. They are usually covered in and concealed by the amygdalae, and cannot be seen until these are draAvn aside. This band is of a semilunar form on each side, its anterior margin being free and concave, its posterior being attached just in front of the furroAved band. BetAveen it and the nodulus and uvula behind, is a deep fossa, called the swallow's nest (nidus hirundinis). Lobes of the Cerebellum. Each hemisphere is divided into an upper and a loAver portion by the great horizontal fissure, Avhich commences in front at the pons, and passes horizontally round the free margin of either hemisphere, back- wards to the middle line. From this primary fissure numerous secondary fissures proceed, Avhich separate the cerebellum into lobes. Upon the upper surface of either hemisphere there are two lobes, separated from each other by a fissure. These are the anterior or square lobe, which extends as far back as the posterior edge of the vermiform process, and the posterior or semi- lunar lobe, Avhich passes from the termination of the preceding to the great hori- zontal fissure. Upon the under surface of either hemisphere there are five lobes, separated by sulci; these are from before backAvards ; the flocculus or subpeduncular lobe, a prominent tuft, situated behind and below the middle peduncle of the cerebellum; its surface is composed of gray matter, subdivided into a few small laminae ; it is sometimes called the pneumogastric lobule, from being situated behind the pneu- mogastric nerve. The amygdala or tonsil is situated on either side of the great median fissure or valley, and projects into the fourth ventricle. The digastric lobe is situated on the outside of the tonsil, being connected in part Avith the pyramid. Behind the digastric is the slender lobe, which is connected Avith the back part of the pyramid and the commissura brevis ; and most posteriorly is the inferior posterior lobe, Avhich also joins the commissura brevis in the valley. Structure of the Cerebellum. If a vertical section is made through either hemi- sphere of the cerebellum, Fig. 249.—Vertical Section of the Cerebellum. midway betAveen its centre and the superior vermiform process, it Avill be found to consist of a central stem of white matter, which con- tains in its interior a den- tate body. From the sur- face of each hemisphere, a series of plates of medul- lary matter are detached, which, covered with gray matter, form the laminae; and from its anterior part arise three large processes or peduncles, superior, middle, and inferior, by which it is connected with the rest of the encephalon. The Laminae are about ten or twelve in number, including those on both surfaces of the organ, those in front being detached at a right angle, and those behind at an acute angle; as each lamina proceeds outwards, other secondary laminae are detached from it, and, from these, tertiary laminae. The arrangement thus described gives to the cut surface of the organ a foliated appearance, to which the name arbor vita? has been CEREBELLUM. 473 given. Each lamina consists of white matter, covered externally by a layer of gray substance. The white matter of each lamina is derived partly from the central stem; in addition to Avhich white fibres pass from one lamina to another. The gray matter resembles someAvhat the cortical substance of the convolu- tions, consisting of two layers, the external one, soft and of a grayish color, the internal one, firmer and of a rust color. The Corpus Dentatum, or Ganglion of the Cerebellum, is situated a little to the inner side of the centre of the stem of Avhite matter. It consists of an open bag or capsule of gray matter, the section of Avhich presents a gray dentated out- line, being open at its anterior part. It is surrounded by Avhite fibres; Avhite fibres are also contained in its interior, Avhich issue from it to join the superior peduncles. The Peduncles of the cerebellum, superior, middle, and inferior, serve to con- nect it with the rest of the encephalon. The Superior Peduncles (Processus e Cerebello ad Testes) connect the cere- bellum with the cerebrum ; they pass forwards and upAvards to the testes, beneath which they ascend to the crura cerebri and optic thalami, forming part of the diverging cerebral fibres : each peduncle forms part of the lateral boundary of the fourth ventricle, and is connected Avith its fellow of the opposite side by the valve of Vieussens. Behind, it is continuous Avith the folia of the inferior vermiform process, and Avith the Avhite fibres in the interior of the corpus dentatum. Beneath the corpora quadrigemina, the innermost fibres of each peduncle decussate with each other, so that some fibres from the right half of the cerebellum are continued to the left half of the cerebrum. The Inferior Peduncles (Processus ad Medullam) connect the cerebellum with the medulla oblongata. They pass doAvmvards, to the back part of the medulla, and form part of the restiform bodies. Above, the fibres of each process are con- nected chiefly with the laminae, on the upper surface of the cerebellum ; and below, they are connected with all three tracts of the half of the medulla, and, through these, v\lth the corresponding half of the cord, excepting the posterior median columns. The Middle Peduncles (Processus ad Pont em), the largest of the three, connect together the tAvo hemispheres of the cerebellum, forming their great transverse commissure. They consist of a mass of curved fibres, Avhich arise in the lateral parts of the cerebellum, and pass across to the same points on the opposite side. They form the transverse fibres of the pons Varolii. Fourth Ventricle. The fourth ventricle, or ventricle of the cerebellum, is the space betAveen the posterior surface of the medulla oblongata and pons in front, and the cerebellum behind. It is lozenge-shaped, being contracted above and below, and broadest across its central part. It is bounded laterally by the processus e cerebello ad testes above, and by the diverging posterior pyramids and restiform bodies below. The roof is arched ; it is formed by the valve of Vieussens and the under sur- face of the cerebellum, which presents in this situation four small eminences or lobules, tAvo occupying the median line, the nodulus and uvula, the remaining two the amygdala?, being placed on either side of the uvula. The anterior boundary, or floor, is formed by the posterior surface of the me- dulla oblongata and pons. In the median line is seen the posterior median fissure; it becomes gradually obliterated above, and terminates below in the point of the calamus scriptorius, formed by the convergence of the posterior pyramids. At this point is the orifice of a short canal terminating in a cul-de-sac, the remains of the canal Avhich extends in fcetal life through the centre of the cord. On each side of the median fissure are two slightly conA'ex longitudinal eminences, the fasciculi teretes; they extend the entire length of the floor, being indistinct below 474 NERVOUS SYSTEM. and of a grayish color, but Avell marked and whitish above. Each eminence con- sists of fibres derived from the lateral tract and restiform body, Avhich ascend to the cerebrum. Opposite the crus cerebelli, on the outer side of the fasciculi teretes, is a small eminence of dark gray substance, which presents a bluish tint through the thin stratum covering it; this is called the locus coeruleus; and a thin streak of the same color continued up from this on either side of the fasciculi teretes, as far as the top of the ventricle, is called the teenia violacea. The lower part of the floor of the ventricle is crossed by several Avhite transverse lines, linece transversa^; they emerge from the posterior median fissure; some enter the crus cerebelli others enter the roots of origin of the auditory nerve, whilst some pass upAvards and outwards on the floor of the ventricle. The Lining Membrane of the fourth ventricle is continuous with that of the third, through the aqueduct of Sylvius, and its cavity communicates below with the subarachnoid space of the brain and cord, through an aperture in the layer of pia mater extending betAveen the cerebellum and medulla oblongata. Laterally, this membrane is reflected outAvards a short distance betAveen the cerebellum and medulla. The Choroid Plexuses of the fourth ventricle are two in number: they are delicate vascular fringes, which project into the ventricle on each side, passing from the point of the inferior vermiform process to the outer margin of the resti- form bodies. The Gray Matter in the floor of the ventricle consists of a tolerably thick stratum, continuous below with the gray commissure of the cord, and extending up as high as the aqueduct of Sylvius, besides some special deposits connected with the roots of origin of certain nerves. In the upper half of the ventricle is a projection situated over the nucleus, from Avhich the sixth and facial nerves take a common origin. In the lower half are three eminences on each side for the roots of origin of the eighth and ninth nerves. Cranial Nerves. rpHE Cranial Nerves, nine in number on each side, include all those which arise -1- from some part of the cerebro-spinal centre, and are transmitted through oramina in the base of the cranium. They have been named numerically, according to the order in Avhich they pass out of this cavity. Their names are also derived from the part to wliich each is distributed, or from the special func- tion appropriated to each. Taken in their order, from before backAvards, they are as follows : 1st. Olfactory. _ , f Facial (Portio dura). 2d. Optic. ' \ Auditory (Portio mollis). 3d. Motores oculorum. f Glosso-pharyngeal. 4th. Pathetic. 8th. < Pneumogastric, or Par vagum. 5th. Trifacial, Trigemini. ( Spinal accessory. 6th. Abducentes. 9th. Hypoglossal. The cranial nerves may be subdivided into three groups, according to the pecu- liar function possessed by each, Ariz., nerves of special sense ; nerves of motion ; and compound nerves, that is, the function of which is both motor and sensitive. These groups may be thus arranged :— 1. Nerves of Special Sense. 1st. Olfactory. 2d. Optic. 7th. Auditory (Portio mollis). 3. 5th. Nerves of Motion. Motores oculorum. Pathetic. Abducentes. Facial (Portio dura). Hypoglossal. 2. 3d. 4th. 6th. 7th. 9th. Compound Nerves. Trifacial. ( Glosso-pharyngeal. 8th. < Pneumogastric. ( Spinal accessory. All the crania] nerves are connected to some part of the surface of the brain. This is termed their superficial or apparent origin. But the fibres may, in all cases, be traced deeply into the substance of the organ. This Avould form their deep or real origin. 1. Nerves of Special Sense. Olfactory Nerve. The First, or Olfactory Nerve, the special nerve of the sense of smell, may be regarded as a portion of the cerebral substance, pushed forward in direct rela- tion with the organ to Avhich it is distributed. It arises by three roots. The external or long root, is a narroAv, white, medullary band, Avhich passes out- wards across the fissure of Sylvius, into the substance of the middle lobe of the cerebrum. Its deep origin may be traced to the corpus striatum,1 the superficial fibres of the optic thalamus,2 the anterior commissure,3 and the convolutions of the island of Reil. The middle or gray root, arises from the papilla of gray matter (caruncula mam- millaris), imbedded in the anterior lobe. This lobe is prolonged into the nerve from the adjacent part of the brain, and contains Avhite fibres in its interior, Avhich are connected Avith the corpus striatum. The internal, or short root, is composed of Avhite fibres, which arise from the 1 Vieussens, Winslow, Monro, Mayo. 2 Valentin. 3 Cruveilhier. 476 CRANIAL NERVES. inner and back part of the anterior lobe, being connected, according to Fovillc, Avith the longitudinal fibres of the gyrus fornicatus. These three roots unite and form a flat band, narroAver in the middle than at either extremity, and its section is of a someAvhat prismoid form. It is of soft texture and contains a considerable amount of gray matter in its substance. As it passes for- Avards, it is contained in a deep sulcus between two convolutions, lying on the under surface of the anterior lobe, on either side of the longitudinal fissure, and is retained in position by the arachnoid membrane Avhich covers it. On reaching the cribriform plate of the ethmoid bone, it expands into an oblong mass of grayish- white substance, the olfactory bulb. From the under part of this bulb are given off numerous filaments, about tAventy in number, Avhich pass through the cribriform foramina, and are distributed to the mucous membrane of the nose. Each fila- ment is surrounded by a tubular prolongation from the dura mater and pia mater the former being lost on the periosteum lining the nose ; the latter, in the neuri- lemma of the nerve. The filaments, as they enter the nares, are divisible into three groups, an inner group, larger than those on the outer Avail, spread out over the upper third of the septum ; a middle set, confined to the roof of the nose; and an outer set, which are distributed over the superior and middle turbinated bones and the surface of the ethmoid in front of them. As the filaments descend, they unite in a plexiform network, and become gradually lost in the lining membrane. Their mode of termination is unknoAvn. The olfactory differs in structure from other nerves, in containing gray matter in its interior, being soft and pulpy in structure, and destitute of neurilemma. Its filaments are deficient in the white substance of Schwann, are not divisible into fibrillae, and resemble the gelatinous fibres in being nucleated, and of a finely granular texture. Optic Nerve. _ The Second, or Optic Nerve, the special nerve of the sense of sight, is distributed exclusively to the eyeball. The nerves of opposite sides are con- nected together at the commissure; and from the back of the commissure they may be traced to the brain, under the name of the optic tracts. The opitic tract, at its connection with the brain, divides into two bands Avhich are con- tinued into the optic thalami, the corpora geniculate, and the corpora quadrigemina. The fibres of origin from the thalamus may be traced partly from its surface, and partly from its interior. From this origin the tract winds obliquely across the under surface of the crus cerebri, in the form of a flattened band, destitute of neurilemma, and is attached to it by its anterior margin. It now assumes a cylindrical form, and as it passes forAvards, is connected with the tuber cinereum and la- mina cinerea, from both of which it receives fibres. According to Foville, it is also con- nected Avith the taenia semicircularis, and the anterior termination of the gyrus fornicatus. It finally joins with the nerve of the opposite side to form the optic commissure. The commissure, somewhat quadrilateral in form, rests upon the olivary pro- cess of the sphenoid bone, being bounded, in front, by the lamina cinerea; be- hind, by the tuber cinereum ; on either side, by the substantia perforata antica. Within the commissure, the optic nerves of the two sides undergo a partial decussation. The fibres which form the inner margin of each tract are continued across from one to the other side of the brain, and have no connection with the optic nerves. These may be regarded as commissural fibres between the thalami Fig. 250.—The Optic Nerves and Optic Tracts. OPTIC; AUDITORY; THIRD. 477 of opposite sides. Some fibres are continued across the anterior border of the chiasma, and connect the optic nerves of the two sides, having no relation with the optic tracts. They may be regarded as commissural fibres between the two retinae. The outer fibres of each tract are continued into the optic nerve of the same side. The central Fig- 251.—Course of the Fibres fibres of each tract are continued into the optic nerve in the 0ptic Commissure* of the opposite side, decussating in the commissure with similar fibres of the opposite tract. The optic nerves arise from the fore part of the commissure, and, diverging from one another, become rounded in form, firm in texture, and are inclosed in a sheath derived from the arachnoid. As each nerve passes through the corresponding optic foramen, it receives a sheath from the dura mater; and as it enters the orbit, this sheath subdivides into tAvo layers, one of AA'hich becomes continuous Avith the periosteum of the'orbit; the other forms a sheath for the nerve, and becomes lost in the sclerotic. The nerve passes through the cavity of the orbit, pierces the sclerotic and choroid coats at the back part of the eyeball, a little to the nasal side of its centre, and expands into the retina. A small artery, the arteria centralis retinae, perforates the optic nerve a little behind the globe, and runs along its interior in a tubular canal of fibrous tissue. It sup- plies the internal surface of the retina, and is accompanied by corresponding veins. Auditory Nerve. The Auditory Nerve (portio mollis of the seventh pair) is the special nerve of the sense of hearing, being distributed exclusively to the internal ear. The hard portion of the seventh pair (portio dura), or facial neiwe, is the motor nerve of the face. It will be described Avith the motor cranial nerves. The auditory nerve arises from numerous white striae, the lineae transversae, which emerge from the posterior median fissure in the anterior Avail, or floor, of the fourth ventricle. It is also connected with the gray matter of the medulla, which corresponds to the locus caeruleus. According to Foville, the roots of this nerve are connected, on the under surface of the middle peduncle, Avith the gray substance of the cerebellum, Avith the flocculus, and with the gray matter at the bor- ders of the calamus scriptorius. The nerve winds round the restiform body, from which it receives fibres, and passes forwards across the posterior border of the crus cerebelli, in company with the facial nerve, from which it is partially separated by a small artery. It then enters the meatus auditorius, in company Avith the facial nerve, and, at the bottom of the meatus, divides into two branches, cochlear and vestibular. The auditory nerve is very soft in texture (hence the name, portio mollis), destitute of neurilemma, and, within the meatus, receives one or tAvo fila- ments from the facial. 2. The Motor Cranial Nerves. Third or Motor Oculi Nerve. The Third Nerve (Motor Oculi) is the chief motor nerve of the muscles of the eyeball. It is a rather large nerve, of rounded form and firm texture, having its apparent origin from the inner surface of the crus cerebri, immediately in front of the pons Varolii. The deep origin may be traced into the substance of the crus, where some of its fibres are connected with the locus niger; others run downwards, among the longitudinal fibres of the pons ; whilst others ascend, to be connected with the tubercula quadrigemina and valve of Vieussens. According to Stilling, the fibres of the nerve pierce the peduncle and locus niger, and arise from a gray nucleus in the floor of the aqueduct of Sylvius. On emerging from the brain, it is invested in a sheath of pia mater, and inclosed in a prolongation from the arachnoid. It then pierces the dura mater on the outer side of the anterior clinoid process, Avhere its serous covering is reflected from it, and passes along the outer Avail of the cavernous sinus, above the other orbital nerves, receiving 478 CRANIAL NERVES. B'fm.rrcchhurTr. in its course one or tAvo filaments from the cavernous plexus of the sympathetic. It then divides into tAvo branches, Avhich enter the orbit through the sphenoidal fissure, betAveen the two Fig. 252.—Nerves of the Orbit. Seen from above. heads of the External rec- tus muscle. On passing through this fissure, this nerve is placed below the fourth, and the frontal and lachrymal branches of the ophthalmic nerve. The superior division, the smaller, passes inAvards across the optic nerve, and supplies the Superior rectus and Levator palpebrae. The inferior division, the larger, divides into three branches. One passes beneath the optic nerve to the Internal rectus: another to the inferior rectus; and the third, the largest of the three, passes forwards be- tAveen the Inferior and Ex- ternal recti, to the Inferior oblique. From the latter, a short, thick branch is given off to the loAver part of the lenticular ganglion, form- ing its inferior root, as well as tAvo filaments to the In- ferior rectus. All these branches enter the muscles on their ocular surface. Sanson/ Mootl Fourth Nerve. The Fourth, or Trochlear nerve, is the smallest of the cranial nerves. It arises from the upper part of the valve of Vieussens, immediately behind the testis, and divides, beneath the corpora quadrigemina, into two fascicul'i; the anterior one arising from a nucleus of gray matter, close to the middle line of the floor of the aqueduct of Sylvius; the posterior one from a gray nucleus, at the upper part of the floor of the fourth ventricle, close to the origin of the fifth nerve. The two nerves are connected together at their origin, by a transverse band of white fibres, which crosses the surface of the velum. The nerve winds round the outer side of the cms cerebri immediately above the pons Varolii, pierces the dura mater in the tree border of the tentorium cerebelli, near the posterior clinoid process, above the oval opening for the fifth nerve, and passes forwards through the outer wall of the cavernous sinus, below the third; but as it enters the orbit, through the sphe- noidal fissure, it becomes the highest of all the nerves. In the orbit, it passes inwards, above the origin of the Levator palpebrae, and finally enters the orbital surface of the Superior oblique muscle. In the outer wall of the cavernous sinus, this nerve receives some filaments from the carotid plexus of the sympathetic. It is not unfrequently blended with the ophthalmic division of the fifth ; and occasionally gives off a branch to assist in the formation of the lachrymal nerve. It also gives off a recurrent branch, which passes backAvards between the layers of the tentorium, dividing into two or three filaments, Avhich may be traced as far back as the wall of the lateral sinus. SIXTH NERVE. 479 Sixth Nerve. The SrxTH Nerve (Abducens) takes its apparent origin by several filaments from the constricted part of the corpus pyramidale, close to the pons, or from the loAver border of the pons itself. The deep origin of this nerve has been traced by Mayo, between the fasciculi of the corpus pyramidale, to the posterior part of the medulla, where Stilling has shoAvn its connection Avith a gray nucleus in the floor of the fourth ventricle*! The nerve pierces the dura mater, immediately beloAV the posterior clinoid pro- cess, lying in a groove by the side of the body of the sphenoid bone. It passes forwards through the_ cavernous sinus, lying on the outer side of the internal carotid artery, Avhere it is joined by several filaments from the carotid plexus, by one from Meckel's ganglion (Bock), and another from the ophthalmic nerve. It enters the orbit through the sphenoidal fissure, and lies above the ophthalmic vein, from which it is separated by a lamina of dura mater. It then passes be- tween the two heads of the External rectus, and is distributed to that muscle on its ocular surface. Fig. 253.—Nerves of the Orbit and Ophthalmic Ganglion. Side view. Relations of the Orbital Nerves. The above-mentioned nerves, as avcII as the ophthalmic division of the fifth, as they pass to the orbit, bear a certain relation to each other in the cavernous sinus, at the sphenoidal fissure, and in the cavity of the orbit, Avhich will be noAv described. In the Cavernous Sinus, the third, fourth, and ophthalmic division of the fifth, are placed in the dura mater, forming the outer Avail of the sinus, in numerical order, both from above downAvards, and from Avithin outAvards. The sixth nerve lies at the outer side of the internal carotid artery. As these nerves pass forAvards to the sphenoidal fissure, the third and fifth nerves become divided, and the sixth approaches the rest; so that their relative position becomes considerably changed. In the Sphenoidal Fissure, the fourth, and the frontal and lachrymal divisions of the ophthalmic, lie upon the same plane, the former being the most internal, the latter external; and they enter the cavity of the orbit above the muscles. The remaining nerves enter that cavity betAveen the tAvo heads of the External rectus. The superior division of the third is the highest; beneath this, the nasal branch of the fifth ; then the inferior division of the third ; and the sixth loAvest of all. In the Orbit, the fourth, and the frontal and lachrymal divisions of the ophthalmic, lie on the same plane immediately beneath the periosteum, the fourth nerve being internal and resting on the Superior oblique, the frontal resting on the Levator 480 CRANIAL NERVES. palpebrae, and the lachrymal on the External rectus. Next in order comes the superior division of the third nerve, lying immediately beneath the Superior rectus and then the nasal division of the fifth crossing the optic nerve from the outer to the inner side of this cavity. Beneath these is found the optic nerve, surrounded in front by the ciliary nerves, and having the lenticular ganglion on its outer side, between it and the External rectus. Below the optic is the inferior division of the third, and the sixth, which lies on the outer side of the cavity. Facial Nerve. The Facial Nerve, portio dura or hard portion of the seventh pair, is the motor nerve of the face. It arises from the lateral tract of the medulla oblongata, in the groove betAveen the olivary and restiform bodies. Its deep origin may be traced to the floor of the fourth ventricle, Avhere it is connected with the same nucleus as the sixth nerve. This nerve is situated a little nearer to the middle line than the portio mollis, close to the lower border of the pons Varolii, from which some of its fibres are derived. Connected Avith this nerve, and lying between it and the portio mollis, is a small fasciculus (portio inter duram et modern of Wrisberg). This accessory portion arises from the lateral column of the cord. The nerve passes forwards and outwards upon the crus cerebelli, and enters the internal auditory meatus with Fig. 254.—The Course and Connections of the Facial Nerve the auditorv nerve. Within empora one. ^e meatus^ ^e facJa] nerve lies first to the inner side of, and then in, a groove upon the auditory nerve, and is con- nected to it by one or two fila- ments. At the bottom of the mea- tus, it enters the aquaeductus Fallopii, and follows the ser- pentine course of that canal through the petrous portion of the temporal bone, from its commencement at the internal meatus to its termination at the stylo-mastoid foramen. It is at first directed outAvards towards the hiatus Fallopii, Avhere it forms a reddish gangliform swelling (intumescentia gangliformis), and is joined by several nerves; bending suddenly backwards, it runs in the internal wall of the cavity of the tympanum, above the fenestra ovalis, and at the back of this cavity passes vertically down- wards to the stylo-mastoid foramen. On emerging from this aperture, it runs forwards in the substance of the parotid gland, crosses the external jugular vein and external carotid artery, and divides behind the ramus of the lower jaw into tAvo primary branches, temporo-facial and cervico-facial, from which numerous offsets are distributed over the side of the head, face, and upper part of the neck, supplying the superficial muscles in this region. The communications of the facial nerve may be thus arranged :— In the internal auditory meatus, . With the auditory nerve. 'With Meckel's ganglion by the large pe- trosal nerve. With the otic ganglion by the small pe- trosal nerve. With the sympathetic on the middle me- ningeal by the external petrosal nerve. With the pneumogastric. " glosso-pharyngeal. " carotid plexus. " auricular is magnus. " auriculotemporal. With the three divisions of the fifth. "External Petrosal Small Petve. Lavyp. jPdf Intumescentia Ganrjlifoi'mis 79.F, In the aquaeductus Fallopii, At its exit from the stylo-mastoid foramen, .... On the face, .... FACIAL. 481 On the face, In the internal auditory meatus, some minute filaments pass between the facial and auditory nerves. Opposite the hiatus Fallopii, the gangliform enlargement on the facial nerve communicates, by means of the large superficial petrosal nerve, Avith Meckel's ganglion ; by a filament from the smaller superficial petrosal, with the otic gan- glion ; and by the external superficial petrosal Avith the sympathetic filaments accompanying the middle meningeal artery (Bidder). From the gangliform enlargement, according to Arnold, a tAvig is sent back to the auditory nerve. At its exit from the stylo-mastoid foramen, it sends a twig to the pneumogastric, another to the glosso-pharyngeal nerve, and communicates with the carotid plexus of the sympathetic, with the great auricular branch of the cervical plexus, with the auriculo-temporal branch of the inferior maxillary nerve in the parotid gland, and on the face Avith the terminal branches of the three divisions of the fifth. Branches of Distribution. Within aquaeductus Fallopii, { Jiym?anJ1C' 1 r [ Chorda tympani. *. •. p .1 , -i (Posterior auricular. At exit from stylo-mastoid ) -r.. c \ Digastric. f01"amen' * ' * \ Stylo-hyoid. f Temporal. Temporo-facial. < Malar. (Infraorbital. f Supramaxillary. Cervico-facial. < Inframaxillary. ( Cervical. The Tympanic Branch is a small filament, which supplies the Stapedius muscle. It arises from the nerve opposite the pyramid. The Chorda Tympani is given off from the facial as it passes vertically down- wards at the back of the tympanum, about a quarter of an inch before its exit from the stylo-mastoid foramen. It ascends from below upivards in a distinct canal, parallel Avith the aquaeductus Fallopii, and enters the cavity of the tym- panum through an opening between the base of the pyramid and the attachment of the membrana tympani, and becomes invested with mucous membrane. It passes forAvards through the cavity of the tympanum, betAveen the handle of the malleus and vertical ramus of the incus, to its anterior inferior angle, and emerges from that cavity through a distinct foramen at the inner side of the Glasserian fissure. It then descends betAveen the two Pterygoid muscles, and meets the gustatory nerve at an acute angle ; after communicating Avith this nerve, it accompanies it to the submaxillary gland; it then joins the submaxillary ganglion, and terminates in the Lingualis muscle. The Posterior jhurieular Nerve arises close to the stylo-mastoid foramen, and passes upAvards in front of the mastoid process, where it is joined by a filament from the auricular branch of the pneumogastric, and communicates with the deep branch of the auricularis magnus; as it ascends between the meatus and the mas- toid process it divides into two branches. The auricular branch supplies the Re- trahens aurem, and the integument at the back part of the auricle. The occipital branch, the larger, passes backAvards along the superior, curved line of the occi- pital bone, and supplies the occipital portion of the Occipito-frontalis and the integument. The Stylo-hyoid is a long slender branch, Avhich passes inAvards, entering the Stylo-hyoid muscle about its middle; it communicates with the sympathetic fila- ments on the external carotid artery. The Digastric Branch usually arises by a common trunk with the preceding: it divides into several filaments, which supply the posterior belly of the Digastric; one of these perforates that muscle to join the glosso-pharyngeal nerve. 33 182 CRANIAL NERVES. The Temporo-facial, the larger of the two terminal branches, passes upwards and forAvards through the parotid gland, across the neck of the condyle of the jaAv, being connected in this situation with the auriculo-temporal branch of the inferior maxillary nerve, and divides into branches, which are distributed over the temple and upper part of the face; these may be divided into three sets, tem- poral, malar, and infraorbital. The temporal branches cross the zygoma to the temporal region, supplying the Attrahens aurem and the integument, and join with the temporal branch of the superior maxillary, and with the auriculo-temporal branch of the inferior maxillary. The more anterior branches supply the frontal portion of the Occipito- Fig. 255.—The Nerves of the Scalp, Face, and Side of the Neck. frontalis, and the Orbicularis palpebrarum muscle, joining with the supraorbital branch of the ophthalmic. The malar branches pass across the malar bone to the outer angle of the orbit, where they supply the Orbicularis and Corrugator supercilii muscles, joining with filaments from the lachrymal and supraorbital nerves; others supply the lower eyelid, joining with filaments of the malar branches of the superior maxillary nerve. The infraorbital, of larger size than the rest, pass horizontally forwards to NINTH OR HYPOGLOSSAL. 483 be distributed between the lower margin of the orbit and the mouth. The super- ficial branches run beneath the skin and above the superficial muscles of the face, Avhich they supply, being distributed to the integument and hair follicles ; some supply the lower eyelid and Pyramidalis nasi, joining, at the inner angle of the orbit, with the infratrochlear and nasal branches of the ophthalmic. The deep branches pass beneath the Levator labii superioris, supply it and the Levator anguli oris, and form a plexus (infraorbital) by joining with the infraorbital branch of the superior maxillary nerve. The Cervico-facial, the other division of the facial nerve, passes obliquely downwards and forwards through the parotid gland, Avhere it is joined by branches from the great auricular nerve; opposite the angle of the lower jaAv it divides into branches, Avhich are distributed on the lower half of the face and upper part of the neck. These may be divided into three sets, buccal, supramaxillary, and inframaxillary. The buccal branches cross the Masseter muscle, join the infraorbital branches of the cervico-facial division of the nerve, and with filaments of the buccal branch of the inferior maxillary nerve. They supply the Buccinator and Orbicularis oris. The supramaxillary branches pass forwards beneath the Platysma and De- pressor anguli oris, supplying the muscles and the integument of the lip and chin, anastomosing Avith the mental branch of the inferior dental nerve. The inframaxillary branches run forward beneath the Platysma, and form a series of arches across the side of the neck over the suprahyoid region. One of these branches descends vertically to join Avith the superficial cervical nerve from the cervical plexus; others supply the Platysma and Levator labii supe- rioris. Ninth or Hypoglossal Nerve. The Ninth or Hypoglossal Nerve is the motor nerve of the tongue. It arises by several filaments, from ten to fifteen in number, from the groove between the pyramidal and olivary bodies, in a continuous line with the anterior roots of the spinal nerves. According to Stilling, these roots may be traced to a gray nucleus in the floor of the medulla oblongata, between the posterior median furrow and the nuclei of the glosso-pharyngeal and vagus nerves. The filaments of this nerve are collected into tAvo bundles, Avhich perforate the dura mater separately, opposite the anterior condyloid foramen, and unite together after their passage through it. The nerve descends almost vertically downwards to a point corre- sponding with the angle of the jaw. It is at first deeply seated beneath the internal carotid and jugular vein, and intimately connected Avith the pneumogastric nerve; it then passes forwards betAveen the vein and artery, and descending the neck, becomes superficial beloAV the Digastric muscle. The nerve then loops round the occipital artery, and crosses the external carotid below the tendon of the Digastric muscle. It passes beneath the Mylo-hyoid muscle, lying between it and the Hyo-glossus, and is connected at the anterior border of the latter muscle with the gustatory nerve; it is then continued forAvards into the Genio-hyo-glossus muscle as far as the tip of the tongue, distributing branches to its substance. The communicating branches of this nerve are Avith the Pneumogastric. First and second cervical nerves. Sympathetic. Gustatory. The communication with the pneumogastric takes place close to the exit of the nerve from the skull, numerous filaments passing betAveen the hypoglossal and second ganglion of the pneumogastric, or both being united so as to form one mass. It communicates with the sympathetic opposite the atlas, by branches derived from the superior cervical ganglion, and in the same situation it is joined by the filament with the loop connecting the tAvo first cervical nerves. 184 CRANIAL NERVES. The communication Avith the gustatory takes place near the anterior border of the Hyo-glossus muscle by numerous filaments, Avhich ascend upon it. The branches of distribution are the Descendens noni. Thyro-hyoid. Muscular. The Descendens Noni is a long slender branch, which quits the hypoglossal Avhere it turns round the occipital artery. It descends obliquely across the sheath of the carotid vessels, and joins just below the middle of the neck, to form a loop Fig. 256.—Hypoglossal Nerve, Cervical Plexus, and their Branches. with the communicating branches from the second and third cervical nerves. From the convexity of this loop, branches pass forAvards to supply the Sterno- hyoid, Sterno-thyroid, and both bellies of the Omo-hyoid. According to Arnold, another filament descends in front of the vessels into the chest, Avhich joins the cardiac and phrenic nerves. The descendens noni is occasionally contained in the sheath of the carotid vessels, being sometimes placed over and sometimes beneath the internal jugular vein. The Thyro-hyoid is a small branch, arising from the hypoglossal near the pos- terior border of the Hyo-glossus ; it passes obliquely across the great cornu of the hyoid bone, and supplies the Thyro-hyoid muscle. The Muscular Branches are distributed to the Stylo-glossus, Hyo-glossus. Genio-hyoid, and Genio-hyo-glossus muscles. At the under surface of the tongue, numerous slender branches pass upwards into the substance of the organ. FIFTH NERVE. 485 3. Compound Craxial Nerves. Fifth Nerve. The Fifth Nerve (Trifacial, Trigeminus) is the largest cranial nerve, and is somewhat analogous to a spinal nerve, in its origin by two roots, and in the existence of a ganglion on its posterior root. The functions of this nerve are various. It is a nerve of special sense, of common sensation, and of motion. It is the nerve of the special sense of taste, the great sensitive nerve of the head and face, and the motor nerve of the muscles of mastication. It arises by tAvo roots, a posterior larger or sensory, and an anterior smaller or motor root. Its superficial origin is from the side of the pons Varolii, a little nearer to its upper than its lower border. The smaller root consists of three-or four bundles; in the larger, the bundles are more numerous, varying in number from seventy to a hundred: the two roots are separated from one another by a few of the transverse fibres of the pons. The deep origin of the larger, or sensory root, may be traced between the transverse fibres of the pons Varolii to the lateral tract of the medulla oblongata, immediately behind the olivary body. According to some anatomists, it is con- nected Avith the gray nucleus at the back part of the medulla, betAveen the fasciculi teretes and restiform columns. By others, it is said to be continuous Avith the fasciculi teretes and lateral column of the cord; and, according to Foville, some of its fibres are connected with the transverse fibres of the pons; Avhilst others enter the cerebellum, spreading out on the surface of its middle peduncle. The motor root has been traced by Bell and Retzius to be connected with the pyramidal body. The tAvo roots of the nerve pass forAvards through an oval opening in the dura mater, at the apex of the petrous portion of the temporal bone : here the fibres of the larger root enter a larger semilunar ganglion (Gasserian), Avhile the smaller root passes beneath it Avithout haAlng any connection Avith it, and joins outside the cranium Avith one of the trunks derived from it. The Gasserian or Semilunar Ganglion is lodged in a depression near the apex of the petrous portion of the temporal bone. It is of a somewhat crescentic form, with its convexity turned forwards. Its upper surface is intimately adherent to the dura mater. Branches. This ganglion receives, on its inner side, filaments from the carotid plexus of the sympathetic; and from it some minute branches are given off to the tentorium cerebelli, and the dura mater, in the middle fossa of the cranium. From its anterior border, which is directed forwards and outAvards, three large branches proceed, the ophthalmic, superior maxillary, and inferior maxillary. The two first divisions of this nerve consist exclusively of fibres derived from the larger root and ganglion, and are solely nerA'es of common sensation. The third, or inferior maxillary, is composed of fibres from both roots. This, therefore, strictly speaking, is the only portion of the fifth nerve which is compound, and which can be said to bear analogy with a spinal nerve. Branches of the Fifth Nerve. (1.) Ophthalmic Nerve. The Ophthalmic, or first division of the fifth, is a sensory nerve. It supplies the eyeball, the lachrymal gland, the mucous lining of the eye and nose, and the integument and muscles of the eyebroAv and forehead (Fig. 25-). It is the smallest of the three divisions of the fifth, arising from the upper part of the Gasserian ganglion. It is a short, flattened band, about an inch in length, which passes for- wards along the outer wall of the cavernous sinus, below the other nerves, and just before entering the orbit, through the sphenoidal fissure, divides into three branches, frontal, lachrymal, and nasal. The ophthalmic nerve is joined by filaments from the cavernous plexus of the sympathetic, and gives off recurrent filaments Avhich pass betAveen the layers of the tentorium, with a branch from the fourth nerve. Its branches are the Lachrymal. Frontal. Nasal. 486 CRANIAL NERVES. The Lachrymal is the smallest of the three branches of the ophthalmic. Not unfrequently, it arises by two filaments, one from the ophthalmic, the other from the fourth; and this, Swran considers as the usual condition. It passes forwards in a separate tube of dura mater, and enters the orbit through the narroAvest part of the sphenoidal fissure. In this cavity, it runs along the upper border of the External rectus muscle, with the lachrymal artery, and is connected with the orbital branch of the superior maxillary nerve. Within the lachrymal gland it gives off several filaments, Avhich supply it and the conjunctiva.. Finally, it pierces the palpebral ligament, and terminates in the integument of the upper eyelid, joinin" with filaments of the facial nerve. The Fronted (Fig. 252) is the largest division of the ophthalmic, and may be regarded, both from its size and direction, as the continuation of this nerve. It enters the orbit above the muscles, through the highest and broadest part of the sphenoidal fissure, and runs forAvards along the middle line, between the Levator palpebrae and the periosteum. MidAvay betAveen the apex and base of this cavity, it divides into tAvo branches, supratrochlear and supraorbital. The supratrochlear branch, the smaller of the tAvo, passes inAvards, above the pulley of the Superior oblique muscle, and gives off a descending filament, which joins with the infratrochlear branch of the nasal nerve. It then escapes from the orbit betAveen the pulley of the Superior oblique and the supraorbital foramen, curves up on to the forehead close to the bone, and ascends behind the Corrugator supercilii, and Occipito-frontalis muscles, to both of which it is distri- buted. Finally, it is lost in the integument of the forehead. The supraorbital branch passes forAvards through the supraorbital foramen, and gives off, in this situation, palpebral filaments to the upper eyelid. It then ascends upon the forehead, and terminates in muscular, cutaneous, and pericranial branches. The muscular branches supply the Corrugator supercilii, Occipito- frontalis, and Orbicularis palpebrarum, joining in the substance of the latter muscle with the facial nerve. The cutaneous branches, two in number, an inner and an outer, supply the integument of the cranium as far back as the occiput. They are at first situated beneath the Occipito-frontalis, the former perforating the frontal portion of the muscle, the latter its tendinous aponeurosis. The pericranial branches are distributed to the pericranium, over the frontal and parietal bones. They are derived from the cutaneous branches Avhilst beneath the muscle. The Nasal Nerve is intermediate in size betAveen the frontal and lachrymal and more deeply placed than the other branches of the ophthalmic. It enters the orbit between the two heads of the External rectus, passes obliquely inwards across the optic nerve, beneath the Levator palpebrae and Superior rectus muscles, to the inner wall of this cavity, where it enters the anterior ethmoidal foramen, immediately below the Superior oblique muscle. It now enters the cavity of the cranium, traverses a shallow groove on the front of the cribriform plate of the ethmoid bone, and passes down, through the slit by the side of the crista galli, into the nose, where it divides into two branches, an internal and an external. The internal branch supplies the mucous membrane near the fore part of the septum of the nose. The external branch descends in a groove on the inner surface of the nasal bone, and supplies a few filaments to the mucous membrane covering the front part of the outer Avail of the nares, as far as the inferior spongy bone; it then leaves the cavity of the nose, between the lower border of the nasal bone and the upper lateral cartilage of the nose, and, passing down beneath the Com- pressor nasi, supplies the integument of the ala and tip of the nose, joining with the facial nerve. The branches of the nasal nerve are the ganglionic, ciliary, and infra- trochlear. The ganglionic is a long, slender branch, about half an inch in length, which usually arises from the nasal, between the two heads of the External rectus. It passes forwards on the outer side of the optic nerve, and enters the superior and SUPERIOR MAXILLARY NERVE. 4.^7 posterior angle of the ciliary ganglion, forming its superior or long root, It is sometimes joined by a filament from the cavernous plexus of the sympathetic, or from the superior division of the third nerve. The long ciliary nerves, two or three in number, are given off from the nasal as it crosses the optic nerve. They join the short ciliary nerves from the ciliary gan- glion, pierce the posterior part of the sclerotic, and, running forwards between it and the choroid, are distributed to the Ciliary muscle and iris. The infratrochlcar branch is given off just as the nasal nerve passes through the anterior ethmoidal foramen. It runs forwards along the upper border of the In- ternal rectus, and is joined, beneath the pulley of the Superior oblique, by a fila- ment from the supratrochlear nerve. It then passes to the inner angle of the eye, and supplies the Orbicularis palpebrarum, the integument of the eyelids, and side of the nose, the conjunctiva, lachrymal sac, and caruncula lacrymalis. (2.) Superior Maxillary Nerve (Fig. 257). The Superior Maxillary, or second division of the fifth, is a sensory nerve. It is intermediate both in position and size, between the ophthalmic and'inferior maxillary. It commences at the middle of the Gasserian ganglion as a flattened plexiform band, passes forwards through the foramen rotundum, where it becomes more cylindrical in form and firmer in texture. It then crosses the spheno- Fig. 257.—Distribution of the Second and Third Divisions of the Fifth Neive and Submaxillary Ganglion. maxillary fossa, traverses the infraorbital canal in the floor of the orbit, emerging upon the face at the infraorbital foramen. At its termination, the nerve lies beneath the Levator labii superioris muscle, and divides into a leash of branches, 488 CRANIAL NERVES. which spread out upon the side of the nose, the lower eyelid, and upper lip, join- ing with filaments of the facial nerve. The branches of this nerve may be divided into three groups : 1. Those given off in the spheno-maxillary fossa. 2. Those in the infraorbital canal. 3. Those on the face. t ( Orbital. In the spheno-maxillary fossa, < Spheno-palatine. (Posterior dental. In the infraorbital canal, . Anterior dental. ( Palpebral. On the face, . . . < Nasal. ( Labial. The Orbital Branch arises in the spheno-maxillary fossa, enters the orbit by the spheno-maxillary fissure, and divides into tAvo brandies, temporal and malar. The temporal branch runs in a groove along the outer Avail of the orbit (in the malar bone), receives a branch of communication from the lachrymal, and passing through a foramen in the malar bone, enters the temporal fossa. It ascends betAveen the bone and substance of the Temporal muscle, pierces this muscle and the temporal fascia about an inch above the zygoma, and is distributed to the integument covering the temple and side of the forehead, communicating with the facial and auriculo-temporal branch of the inferior maxillary nerve. The malar branch passes along the external inferior angle of the orbit, emerges upon the face through a foramen in the malar bone, and perforating the Orbi- cularis palpebrarum muscle on the prominence of the cheek, joins with the facial. The Spheno-palatine Branches, tAvo in number, descend to the spheno-palatine ganglion. The Posterior Dental Branches arise from the trunk of the nerve just as it is about to enter the infraorbital canal ; they are two in number, posterior and anterior. The posterior branch passes from behind forwards in the substance'of the superior maxillary bone, and joins opposite the canine fossa Avith the anterior dental. Numerous filaments are given off from the lower border of this nerve, which form a minute plexus in the outer Avail of the superior maxillary bone im- mediately above the alveolus. From this plexus, filaments are distributed to the pulps of the molar and bicuspid teeth, the lining membrane of the antrum, and cor- responding portion of the gums. The anterior branch is distributed to the gums and Buccinator muscle. The^ Anterior Dental, of large size, is given off from the superior maxillary nerve just before its exit from the infraorbital foramen ; it enters a special canal in the anterior Avail of the antrum, and anastomoses with the posterior dental. From this branch filaments are distributed to the incisor, canine, and first bicuspid teeth; others are lost upon the lining membrane covering the front part of the inferior meatus. The Palpebral Branches pass upAvards beneath the Orbicularis palpebrarum. They supply this muscle, the integument, and conjunctiva of the lower eyelid, joining at the outer angle of the oibit with the facial nerve and malar branch of the orbital. The Nasal Branches pass inwards ; they supply the muscles and integument of the side of the nose, and join with the nasal branch of the ophthalmic. The Labial Branches, the largest and most numerous, descend beneath the Levator labii superioris, and are distributed to the integument and muscles of the upper hp, the mucous membrane of the mouth, and labial glands. All these branches are joined, immediately beneath the orbit, by filaments from the facial nerve, forming an intricate plexus, the infraorbital. INFERIOR MAXILLARY NERVE. 489 (3.) Inferior Maxillary Nerve. The Inferior Maxillary Nerve distributes branches to the teeth and gums of the lower jaAv, the integument of the temple and external ear, loAver part of the face and lower lip, and the muscles of mastication ; it also supplies the tongue with its special nerve of the sense of taste. It is the largest of the three divisions of the fifth, and consists of two portions, the larger, or sensory root, proceeding from the inferior angle of the Gasserian ganglion ; and the smaller, or motor root, which passes beneath the ganglion, and unites with the inferior maxillary nerve, just after its exit through the foramen ovale. Immediately beneath the base of the skull, this nerve diA'ides into tAvo trunks, anterior and posterior. The anterior, and smaller division, Avhich receives nearly the Avhole of the motor root, divides into five branches, Avhich supply the muscles of mastication. They are the masseteric, deep temporal, buccal, and pterygoid. The Masseteric Branch passes outAvards, above the External pterygoid muscle, in front of the temporo-maxillary articulation, and crosses the sigmoid notch, Avith the masseteric artery, to the Masseter muscle, in Avhich it ramifies nearly as far as its anterior border. It occasionally gives a branch to the Temporal muscle, and a filament to the articulation of the jaw. The Deep Temporal Branches, tAvo in number, anterior and posterior, supply the deep surface of the Temporal muscle. The posterior branch, of small size, is placed at the back of the temporal fossa. It is sometimes joined Avith the masseteric branch. The anterior branch is reflected upAvards, at the pterygoid ridge of the sphenoid, to the front of the temporal fossa. It is occasionally joined with the buccal nerve. The Buccal Branch pierces the External pterygoid, and passes doAvmvards be- neath the inner surface of the coronoid process of the lower jaAv, or through the fibres of the Temporal muscle to reach the surface of the Buccinator, upon Avhich it divides into a superior and an inferior branch. It gives a branch to the External pterygoid during its passage through this muscle, and a few ascending filaments to the Temporal muscle, one of Avhich occasionally joins with the anterior branch of the deep temporal nerve. The upper branch supplies the integument and upper part of the Buccinator muscle, joining Avith the facial nerve around the facial vein. The loiver branch passes forAvards to the angle of the mouth; supplies the integument and Buccinator muscle, as Avell as the mucous membrane lining its inner surface, joining with the facial nerve. The Pterygoid Branches are tAvo in number, one for each Pterygoid muscle. The branch to the Internal pterygoid is long and slender, and passes inAvards to enter the deep surface of the muscle. This nerve is intimately connected at its origin Avith the otic ganglion. The branch to the External pterygoid is most frequently derived from the buccal, but it may be given off separately from the anterior trunk of the nerve. The posterior and larger division of the inferior maxillary nerve also receives a feAV filaments from the motor root. It divides into three branches, auriculo- temporal, gustatory, and inferior dental. The Auriculo-temporal Nerve generally arises by two roots, betAveen Avhich passes the middle meningeal artery. It passes backwards beneath the External pterygoid muscle to the inner side of the articulation of the lower jaw. It then turns upAvards Avith the temporal artery, betAveen the external ear and condyle of the jaAv, under cover of the parotid gland, and escaping from beneath this struc- ture, divides into two temporal branches. The posterior temporal, the smaller of the two, supplies the Attrahens aurem muscle, and is distributed to the upper part of the pinna and the neighboring integument. The anterior temporal accompanies the temporal artery to the vertex of the skull, and supplies the integument of the temporal region, communicating with the facial nerve. The auriculo-temporal nerve has branches of communication Avith the facial nerve and otic ganglion. Those joining the facial nerve, usually two in number, pass 490 CRANIAL NERVES. forwards behind the neck of the condyle of the jaAv, and join this nerve at the posterior border of the Masseter muscle. They form one of the principal branches of communication betAveen the facial and the fifth nerve. The filaments of com- munication Avith the otic ganglion are derived from the commencement of the auriculo-temporal nerve. The Auricular Branches are tAvo in number, inferior and superior. The infe- rior auricular arises behind the articulation of the jaw, and is distributed to the car below the external meatus; other filaments tAvine around the internal maxil- lary artery, and communicate Avith the sympathetic. The superior auricular arises in front of the internal ear, and supplies the integument covering the tragus and pinna. Branches to the Meatus Auditorius, tAvo in number, arise from the point of communication between the temporo-auricular and facial nerves, and are distri- buted to the meatus. The Branch to the. Temporo-maxillary Articulation is usually derived from the auriculo-temporal nerve. The Parotid Branches supply the parotid gland. The Gustatory or Lingual Nerve (Fig. -&!), the special nerve of the sense of taste, supplies the papillae and mucous membrane of the tongue. It is deeply placed throughout the Avhole of its course. It lies at first beneath the External pterygoid muscle, together with the inferior dental nerve, being placed to the inner side of the latter nerve, and is occasionally joined to it by a branch Avhich crosses the internal maxillary artery. The chorda tympani also joins it at an acute angle in this situation. The nerve then passes betAveen the Internal pterygoid muscle and the inner side of the ramus of the jaAv, and crosses obliquely to the side of the tongue over the Superior constrictor muscle of the pharynx, and be- tAveen the stylo-glossus muscle and deep part of the submaxillary gland; the nerve lastly runs across Wharton's duct, and along the side of the tongue to its apex, being covered by the mucous membrane of the mouth. Its branches of communication are Avith the submaxillary ganglion and hypo- glossal nerve. The branches to the submaxillary ganglion are two or three in number; those connected with the hypoglossal nerve form a plexus at the anterior margin of the Hyo-glossus muscle. Its branches of distribution are feAV in number. They supply the mucous mem- brane of the mouth, the gums, the sublingual gland, and the conical and fungiform papillae and mucous membrane of the tongue,.the terminal filaments anastomosing at the tip of this organ Avith the hypoglossal nerve. The Inferior Dental is the largest of the three branches of the inferior max- illary nerve. It passes downwards with the inferior dental artery, at first beneath the External pterygoid muscle, and then betAveen the internal lateral ligament and the ramus of the jaw to the dental foramen. It then passes forAvards in the dental canal in the inferior maxillary bone, lying beneath the teeth, as far as the mental foramen, where it divides into two terminal branches, incisor and mental. The incisor branch is continued onwards within the bone to the middle line, and supplies the canine and incisor teeth. The mental branch emerges from the bone at the mental foramen, and divides beneath the Depressor anguli oris into an external branch, which supplies this muscle, the Orbicularis oris, and the integument, com- municating with the facial nerve ; and an inner branch, which ascends to the lower lip beneath the Quadratus menti; it supplies this muscle, and the mucous mem- brane and integument of the lip, communicating with the facial nerve. The branches of the inferior dental are the mylo-hyoid and dental. The Mylo-hyoid is derived from the inferior dental just as that nerve is about to enter the dental foramen. It descends in a groove on the inner surface of the ramus of the jaw, in which it is retained by a process of fibrous membrane. It supplies the cutaneous surface of the Mylo-hyoid muscle, and the anterior belly of the Digastric, occasionally sending one or two filaments to the submaxillary gland. SPIIENO-PALATINE GANGLION. 491 The Dental Branches supply the molar and bicuspid teeth. They correspond in number to the fangs of those teeth; each nerve entering the orifice at the point of the fang, and supplying the pulp of the tooth. Two small ganglia are connected with the inferior maxillary nerve : the otic, with the trunk of the nerve ; and the submaxillary, with its lingual branch, the gustatory. Ganglia connected avith the Fifth Nerve. Connected Avith the three divisions of the fifth nerve are four small ganglia, which form the whole of the cephalic portion of the sympathetic. With the first division is connected the ophthalmic ganglion ; Avith the second division, the spheno- palatine or Meckel's ganglion ; and with the third, the otic and submaxillary gan- glia. These ganglia receive sensitive filaments from the fifth, and motor filaments from other sources ; these filaments are called the roots of the ganglia. They are also connected with each other, and Avith the cervical portion of the sympathetic. (1.) Ophthalmic or Ciliary Ganglion. The Ophthalmic, Lenticular, or Ciliary Ganglion (Fig. 253), is a small quadrangular flattened ganglion, of a reddish-gray color, and about the size of a pin's head, situated at the back part of the orbit betAveen the optic nerve and the External rectus muscle, generally lying on the outer side of the ophthalmic artery. It is inclosed in a quantity of loose fat, Avhich makes its dissection someAvhat difficult. Its branches of communication, or its roots, are three, all of which enter its pos- terior border. One, the long root, is derived from the nasal branch of the oph- thalmic, and joins its superior angle. Another branch, the short root, is a short thick nerve, occasionally divided into tAvo parts ; it is derived from that branch of the third nerve which supplies the Inferior oblique muscle, and is connected with the inferior angle of the ganglion. A third branch, the sympathetic root, is a slender filament from the cavernous plexus of the sympathetic. This is occasionally blended Avith the long root, and sometimes passes to the ganglion by itself. Ac- cording to Tiedemann, this ganglion receives a filament of communication from the spheno-palatine ganglion. Its brandies of distribution are the short ciliary nerves. These consist of from ten to twelve delicate filaments, wliich arise from the fore part of the ganglion in two bundles, connected with its superior and inferior angles : the upper bundle consisting of four filaments, and the lower of six or seven. They run forAvards with the ciliary arteries in a Avavy course, one set above and the other below the optic nerve, pierce the sclerotic at the back part of the globe, pass forAvards in delicate grooves on its inner surface, and are distributed to the Ciliary muscle and iris. A small filament is described by Tiedemann, penetrating the optic nerve Avith the arteria centralis retinae. (2.) Spheno-palatine Ganglion. The Spheno-palatine, or Meckel's Ganglion (Fig. 258), the largest of the cranial ganglia, is deeply placed in the sph mo-maxillary fossa, close to the spheno- palatine foramen. It is triangular, or heart-shaped in form, of a reddish-gray color, and placed mainly behind the palatine branches of the superior maxillary nerve, at the point where the sympathetic root joins the ganglion. It conse- quently does not involve those nerves which pass to the palate and nose. Like other ganglia, it possesses a motor, a sensory, and a sympathetic root. Its motor root is derived from the facial, through the Vidian ; its sensory root from the fifth and its sympathetic root from the carotid plexus, through the Vidian. Its branches are divisible into four groups: ascending, which pass to the orbit; descend- ing, to the palate ; internal, to the nose ; and posterior branches to the pharynx. The Ascending Branches are tAvo or three delicate filaments, which enter the 492 CRANIAL NERVES. orbit by the spheno-maxillary fissure, and supply the periosteum. Arnold de- scribes and delineates these branches as ascending to the optic nerve; one, to the sixth nerve (Bock); and one, to the ophthalmic ganglia (Tiedemann). The Descending or Palatine Branches are distributed to the roof of the mouth the soft palate, tonsil, and lining membrane of the nose. They are almost a direct continuation of the spheno-palatine branches of the superior maxillary nerve, and are three in number, anterior, middle, and posterior. The anterior, or large palatine nerve, descends through the posterior palatine canal, emerges upon the hard palate, at the posterior palatine foramen, and passes forAvards through a groove in the hard palate, extending nearly to the incisor teeth. Fig. 258.—The Spheno-palatine Ganglion and its Branches. It supplies the gums, the mucous membrane and glands of the hard palate, and com- municates in front with the termination of the naso-palatine nerve. While in the posterior palatine canal, it gives off inferior nasal branches, wliich enter the nose through openings in the palate bone, and ramify over the middle meatus, and the middle and inferior spongy bones; and, at its exit from the canal, a palatine branch is distributed to both surfaces of the soft palate. The middle, or external palatine nerve, descends in the same canal as the pre- ceding, to the posterior palatine foramen, distributing branches to the uvula, tonsil, and soft palate. It is occasionally wanting. The posterior, or small palatine nerve, descends with a small artery through the small posterior palatine canal, emerging by a separate opening behind the posterior palatine foramen. It supplies the Levator palati muscle, the soft palate, tonsil, and uvula. The Internal Branches are distributed to the septum, and outer wall of the nasal fossae. They are the superior nasal (anterior), and the naso-palatine. The superior nasal branches (anterior), four or five in number, enter the back part of the nasal fossa, by the spheno-palatine foramen. They supply the mucous membrane covering the superior and middle spongy bones, and that lining the posterior ethmoidal cells, a few being prolonged to the'upper and back part of the septum. OTIC GANGLION. 493 The naso-palatine_ nerve (Cotunnius) enters the nasal fossa with the other nasal nerves, and passes inAvards across the roof of the nose, below the orifice of the sphenoidal sinus, to reach the septum; and then obliquely doAvnwards and forAvards along its loAver part, lying between the periosteum and pituitary membrane to the anterior palatine foramen. It descends to the roof of the mouth by a distinct canal, which opens beloAv in the anterior palatine fossa; the right nerve, also in a separate canal, being posterior to the left one. In the mouth, they become united, supply the mucous membrane behind the incisor teeth, joining Avith the ante- rior palatine nerve. It occasionally furnishes a feAV small filaments to the mucous membrane of the septum. The Posterior Branches are the Vidian and pharyngeal (pterygo-palatine). The Vidian arises from the back part of the spheno-palatine ganglion, passes through the Vidian canal, enters the cartilage filling in the foramen lacerum basis cranii, and divides into two branches, the superficial petrosal, and the carotid. In its course along the Vidian canal, it distributes a few filaments to the lining membrane at the back part of the roof of the nose and septum, and that covering the end of the Eustachian tube. These are upper posterior nasal branches. The petrosal branch (nervus petrosus superficialis major) enters the cranium through the foramen lacerum basis cranii, having pierced the cartilaginous sub- stance filling in this aperture. It runs beneath the Gasserian ganglion and dura mater, contained in a grooAre in the anterior surface of the petrous portion of the temporal bone, enters the hiatus Fallopii, and, being continued through it, into the aquaeductus Fallopii, joins the gangliform enlargement on the facial nerve. Pro- perly speaking, this nerve passes from the facial to the spheno-palatine ganglion, forming its motor root. The carotid branch is shorter, but larger than the petrosal, of a reddish-gray color and soft in texture. It crosses the foramen lacerum, surrounded by the cartilaginous substance Avhich fills in that aperture, and enters the carotid canal, on the outer side of the carotid artery, to join the carotid plexus. The pharyngcid nerve (pterygo-palatine) is a small branch arising from the back part of the ganglion, occasionally springing from the Vidian nerve. It passes through the pterygo-palatine canal Avith the pterygo-palatine artery, and is distributed to the lining membrane of the pharynx, behind the Eustachian tube. (3.) Otic Ganglion. The Otic Ganglion (Arnold's) (Fig. 259) is a small, oval-shaped, flattened gan- glion, of a reddish-gray color, situated immediately beloAV the foramen ovale, on the inner surface of the inferior maxillary nerve, and around the origin of the internal pterygoid nerve. It is in relation, externally, Avith the trunk of the infe- rior maxillary nerve, at the point where the motor root joins the sensory portion ; internally, with the cartilaginous part of the Eustachian tube, and the origin of the Tensor palati muscle; behind it, is the middle meningeal artery. Branches of Communication. This ganglion is connected with the inferior maxillary neiwe, and its internal pterygoid branch, by two or three short, delicate filaments, and also Avith the auriculo-temporal nerve : from the former it obtains its motor, from the latter its sensory root; its communication with the sympa- thetic being effected by a filament from the plexus surrounding the middle meningeal artery. This ganglion also communicates Avith the glosso-pharyngeal and facial nerves, through the small petrosal nerve continued from the tympanic plexus. Its Branches of Distribution, are a filament to the Tensor tympani, and one to the Tensor palati. The former passes backwards, on the outer side of the Eusta- chian tube; the latter arises from the ganglion, near the origin of the internal pterygoid nerve, and passes forAvards. 491 CRANIAL NERVES. (4.) Submaxillary Gangliox. The Submaxillary Ganglion (Fig. 257) is of small size, circular in form, and situated above the deep portion of the submaxillary gland, near the posterior border of the mylo-hyoid muscle, being connected by filaments with the lower border of the gustatory nerve. Fig. 259.—The Otic Ganglion and its Branches. Branches of Communication. This ganglion is connected with the gustatory nerve by a few filaments which join it separately, at its fore and back part. It also receives a branch from the chorda tympani, by which it communicates with the facial ; and communicates with the sympathetic by filaments from the nervi molles, surrounding the facial artery. Branches of Distribution. These are five or six in number; they arise from the lower part of the ganglion, and supply the mucous membrane of the mouth and Wharton's duct, some being lost in the submaxillary gland. According to Meckel, a branch from this ganglion occasionally descends in front of the Hyo-glossus muscle, and, after joining with one from the hypoglossal, passes to the Genio- hyo-glossus muscle. Eighth Pair. The Eighth Pair consists of three nerves, the glosso-pharyngeal, pneumo- gastric, and spinal accessory. The Glosso-pharynoeal Nerve is dis- tributed, as its name implies, to the tongue and pharynx, being the nerve of sensation to the mucous membrane of the fauces and root of the tongue ; and of motion to the Pharyngeal muscles. It arises by three or four filaments, closely connected together, from the upper part of the medulla oblongata, immediately behind the olivary body. Its deep origin may be traced through the fasciculi of the lateral tract, to a nucleus of gray matter at the loAver part of the floor of the fourth ventricle, external to the fasciculi teretes. hrom its superficial origin, it passes outward across the flocculus, and Fig. 2f.o.—Origin of the Eighth Pair, with the Ganglia and Communications. EICHTH PAIR. 495 leaves the skull at the central part of the jugular foramen, in a separate sheath of the dura mater and arachnoid, in front of the pneumogastric and spinal acces- sory nerves. In its passage through the jugular foramen, it grooves the lower border of the petrous portion of the temporal bone, and, at its exit from the skull, passes forwards betAveen the jugular vein and internal carotid artery, and descends in front of the latter vessel, and Fig. 261.—Course and Distribution of the Eighth Pair of Nerves. beneath the styloid process and the mus- cles connected Avith it, to the loAver bor- der of the Stylo- pharyngeus. The nerve noAv curves inwards, forming an arch on the side of the neck, lying upon the Stylo-pharyn- geus, and the Mid- dle constrictor of the pharynx, above the superior laryngeal nerve. It then passes beneath the Hyo- glossus, and is finally distributed to the mucous membrane of the fauces, and base of the tongue, the mucous glands of the mouth and tonsil. The branches of the glossopharyn- geal nerve are the carotid, pharyngeal, muscular, tonsillitic, and lingual. Th e Carotii I Bra n ch - es descend along the trunk of the internal carotid artery as far as its point of bifur- cation, communica- ting Avith the pharyn- geal branch of the pneumogastric, and with branches of the sympathetic. The Pharyngeal Branches are three or four filaments which unite opposite the Middle constric- tor of the pharynx Avith the pharyngeal branches of the pneu- mogastric, superior laryngeal, and sympathetic nerves, to form the pharyngeal 49G CRANIAL NERVES. plexus, branches from which perforate the muscular coat of the pharynx to supply the mucous membrane. The Muscular Branches are distributed to the Stylo-pharyngeus and Con- strictors of the pharynx. The Tonsillitic Branches supply the tonsil, forming a plexus (circulus tonsil- laris) around this body, from Avhich branches are distributed to the soft palate and fauces, where they anastomose with the palatine nerves. The Lingual Branches are tAvo in number; one supplies the mucous membrane covering the surface of the base of the tongue, the other perforates its substance, and supplies the mucous membrane and papillae of the side of the organ. In passing through the jugular foramen, the nerve presents, in succession, two gangliform enlargements. The superior one, the smaller, is called the jugular ganglion, the inferior, and larger one, the petrous ganglion, or the ganglion of Andersch. The Superior or Jugular Ganglion is situated in the upper part of the groove in which the nerve is lodged during its passage through the jugular foramen. It is of very small size, and involves only the outer side of the trunk of the nerve, a small fasciculus passing beyond it, which is not connected directly with it. The Inferior or Petrous Ganglion is situated in a depression in the lower border of the petrous portion of the temporal bone; it is larger than the former, and involves the Avhole of the fibres of the nerve. From this ganglion arise those filaments which connect the glosso-pharyngeal with other nerves at the base of the skull. Its Branches of Communication are Avith the pneumogastric, sympathetic, and facial, and the tympanic branch. The branches to the pneumogastric are tAvo filaments, one to its auricular branch, and one to the upper ganglion of the pneumogastric. The branch to the sympathetic is connected with the superior cervical ganglion. The branch of communication with the facial perforates the posterior belly of the Digastric. It arises from the trunk of the nerve beloAv the petrous ganglion, and joins the facial just after its exit from the stylo-mastoid foramen. The tympanic branch (Jacobson's nerve) arises from the petrous ganglion, and enters a small bony canal on the base of the petrous portion of the temporal bone. (This opening is placed on the bony ridge Avhich separates the carotid canal from the jugular fossa.) It ascends to the tympanum, enters this cavity by an aperture in its floor close to the inner Avail, and divides into three branches, Avhich are con- tained in grooves upon the surface of the promontory. Its Branches of Distribution are, one to the fenestra rotunda, one to the fenestra oval is, and one to the lining membrane of the Eustachian tube and tympanum. Its Branches of Communication are three, and occupy separate grooves on the surface of the promontory. One of these passes forwards and doAvnwards to the carotid canal to join the carotid plexus. A second runs vertically upwards to join the greater superficial petrosal nerve, as it lies in the hiatus Fallopii. The third branch runs upwards and forAvards towards the anterior surface of the petrous bone, and passes through a small aperture in the sphenoid and temporal bones, to the exterior of the skull, where it joins the otic ganglion. This nerve, in its course through the temporal bone, passes by the gangliform enlargement of the facial, and has a connecting filament Avith it. The Spinal Accessory Nerve consists of two parts: one, the accessory part, to the vagus, and the other the spinal portion. The accessory part, the smaller of the two, arises by four or five delicate fila- . ments from the lateral tract of the cord beloAV the roots of the vagus; these fila- ments may be traced to a nucleus of gray matter at the back of the medulla, below the origin of the vagus. It joins, in the jugular foramen, with the upper ganglion of the vagus by one or two filaments, and is continued into the vagus below the second ganglion. It gives branches to the pharyngeal and superior laryngeal branches of the vagus. EIGHTH PAIR. 497 The spinal portion, firm in texture, arises by several filaments from the lateral tract of the cord, as low doAvn as the sixth cervical nerve ; the fibres pierce the tract, and are connected Avith the anterior horn of the gray crescent of the cord. This portion of the nerve ascends betAveen the ligamentum denticulatum and the posterior roots of the spinal nerves, enters the skull through the foramen mag- num, and is then directed outAvards to the jugular foramen, through Avhich it passes, lying in the same sheath as the pneumogastric, separated from it by a fold of the arachnoid, and is here connected with the accessory portion. At its exit from the jugular foramen, it passes backAvards behind the internal jugular vein, and descends obliquely behind the Digastric and Stylo-hyoid muscles to the upper part of the Sterno-mastoid. It pierces this muscle, and passes obliquely across the suboccipital triangle, to terminate in the deep surface of the Trapezius. This nerve gives several branches to the Sterno-mastoid during its passage through it, and joins in its substance with branches from the third cervical. In the suboccipital triangle it joins with the second and third cervical nerves, assists in the formation of the cervical plexus, and occasionally of the great auricular nerve. On the front of the Trapezius, it is reinforced by branches from the third, fourth, and fifth cervical nerves, joins with the posterior branches of the spinal nerves, and is distributed to the Trapezius, some filaments ascending and others descending in its substance as far as its inferior angle. The Pneumogastric, or Vagus, one of the three divisions of the eighth pair, has a more extensive distribution than any of the other cranial nerves, passing through the neck and cavity of the chest to the upper part of the abdomen. It is composed of both motor and sensitive filaments. It supplies the organs of voice and respiration with motor and sensitive fibres; and the pharynx, oesophagus, stomach, and heart with motor influence. Its superficial origin is by eight or ten filaments from the lateral tract immediately behind the olivary body and below the glosso- pharyngeal ; its fibres may, hoAvever, be traced deeply through the fasciculi of the medulla, to terminate in a gray nucleus near the loAver part of the floor of the fourth A-entricle. The filaments become united, and form a flat cord, which passes outwards across the flocculus to the jugular foramen, through Avhich it emerges from the cranium. In passing through this opening, the pneumogastric accom- panies the spinal accessory, being contained in the same sheath of dura mater with it, a membranous septum separating it from the glosso-pharyngeal, Avhich lies in front. The nerve in this situation presents a well-marked ganglionic enlargement, which is called the ganglion jugulare, or the ganglion of the root of the pneumo- gastric : to it the accessory part of the spinal accessory nerve is connected. After the exit of the nerve from the jugular foramen, a second gangliform swelling is formed upon it, called the ganglion inferius, or the ganglion of the trunk of the nerve ; below Avhich it is again joined by filaments from the spinal accessory nerve. The nerve descends the neck in a straight direction within the sheath of the carotid vessels, lying between the internal carotid artery and internal jugular vein as far as the thyroid cartilage, and then betAveen the same vein and the common carotid to the root of the neck. Here the course of the nerve becomes different on the two sides of the body. On the right side, the nerve passes across the subclavian artery between it and the subclavian vein, and descends by the side of the trachea to the back part of the root of the lung, Avhere it spreads out in a plexiform network (posterior pulmonary), from the loAver part of which tAvo cords descend upon the oesophagus, on A\liich they divide, forming, Avith branches from the opposite nerve, the oesophageal plexus; below, these branches are collected into a single cord, AA'hich runs along the back part of the oesophagus, enters the abdomen, and is distributed to the posterior surface of the stomach, joining the left side of the cceliac plexus, and the splenic plexus. On the left side, the pneumogastric nerve enters the chest, betAveen the left carotid and subclavian arteries, behind the left innominate vein. It crosses the 34 498 CRANIAL NERVES. arch of the aorta, and descends behind the root of the left lung and alono* the anterior surface of the oesophagus to the stomach, distributing branches over its anterior surface, some extending over the great cul-de-sac, and others alono* the lesser cunrature. Filaments from these latter branches enter the gastro-hepatic omentum, and join the left hepatic plexus. The Ganglion of the Root is of a grayish color, circular in form, about tAvo lines in diameter, and resembles the ganglion on the large root of the fifth nerve. Connecting Branches. To this ganglion the accessory portion of the spinal acces- sory nerve is connected by seA-eral delicate filaments: it also has an anastomotic twig Avith the petrous ganglion of the glosso-pharyngeal, with the facial nerve by means of the auricular branch, and with the sympathetic by means of an ascend- ing filament from the superior cervical ganglion. The Ganglion of the Trunk (inferior) is aplexiform cord, cylindrical in form of a reddish color, and about an inch in length ; it inA'olves the Avhole of the fibres of the nerve, except the portion of the accessory nerve derived from the spinal acces- sory, which blends Avith the nerve beyond the ganglion. Connecting Branches. This ganglion is connected with the hypoglossal, the superior cervical ganglion of the sympathetic, and with the loop betAveen the first and second cervical nerves. The Branches of the Pneumogastric are In the jugular fossa, . . Auricular. f Pharyngeal. In the neck, . . J £»pe«or laryngeal \ Recurrent laryngeal. (_ Cervical cardiac. f Thoracic cardiac. In the thorax, . . J Anterior pulmonary. I Posterior Pulmonary. (^(Esophageal. In the abdomen, . . Gastric. The Auricular Branch arises from the ganglion of the root, and is joined soon after its origin by a filament from the glosso-pharyngeal; it crosses the jugular fossa to an opening near the root of the styloid process. Traversing the substance of the temporal bone, it crosses the aqiueductus Fallopii about two lines above its termination at the stylo-mastoid foramen ; it here gives off an ascending branch which joins the facial, and a descending branch, which anastomoses with the pos- terior auricular branch of the same nerve : the continuation of the nerve reaches the surface between the mastoid process and the external auditory meatus, and supplies the integument at the back part of the pinna. The Pharyngeal Branch arises from the upper part of the inferior ganglion of the pneumogastric, receiving a filament from the accessory portion of the spinal accessory ; it passes across the internal carotid artery (in front or behind), to the upper border of the Middle constrictor, where it divides into numerous filaments, which anastomose with those from the glosso-pharyngeal, superior laryngeal, and sympathetic, to form the pharyngeal plexus, from 'which branches are distributed to the muscles and mucous membrane of the pharynx. As this nerve crosses the internal carotid, some filaments are distributed, together with those from the glosso-pharyngeal, upon the wall of this vessel. The Superior Laryngeal Nerve, larger than the preceding, arises from the middle of the inferior ganglion of the pneumogastric. It descends, by the side of the pharynx, behind the internal carotid, where it divides into two branches, the external and internal laryngeal. The external laryngeal branch, the smaller, descends by the side of the larynx, beneath the Sterno-thyroid, to supply the crico-thyroid and the thyroid BRANCHES OF PNEUMOGASTRIC. 499 gland. It gives branches to the pharyngeal plexus, and the Inferior constrictor, and communicates with the superior cardiac nerve, behind the common carotid. The internal laryngeal branch descends to the opening in the thyro-hyoid membrane, through which it passes Avith the superior laryngeal artery, and is distributed to the mucous membrane of the larynx, and the Arytenoid muscle, anastomosing with the recurrent laryngeal. The branches to the mucous membrane are distributed, some in front, to the epiglottis, the base of the tongue, and epiglottidean gland ; and others pass back- wards, in the aryteno-epiglottidean fold, to supply the mucous membrane sur- rounding the superior orifice of the larynx, as well as the membrane which lines the cavity.of the larynx as Ioav down as the A'ocal chord. The filament to the Arytenoid muscle is distributed partly to it, and partly to the mucous lining of the larynx. The filament which joins with the recurrent laryngeal descends beneath the mucous membrane on the posterior surface of the larynx, behind the lateral part of the thyroid cartilage, where the tAvo nerves become united. The Inferior or Recurrent Laryngeal, so called from its reflected course, arises, on the right side, in front of the subclavian artery : it winds round this vessel, and ascends obliquely to the side of the trachea, behind the common carotid and inferior thyroid arteries.- On the left side, it arises in front of the arch of the aorta, and Avinds round it at the point Avhere the obliterated remains of the ductus arteriosus are connected Avith this vessel, and then ascends to the side of the trachea. The nerves on both sides ascend in the grooA'e between the trachea and oesophagus, and, piercing the lowest fibres of the Inferior constrictor muscle, enter the larynx behind the articulation of the inferior cornu of the thyroid cartilage Avith the cricoid, being distributed to all the muscles of the larynx, excepting the Crico-thyroid, and joining with the superior laryngeal. The recurrent laryngeal, as it AAunds round the subclavian artery and aorta, gives off several cardiac filaments, which unite with the cardiac branch from the pneumogastric and sympathetic. As it ascends the neck, it gives off oesophageal branches, more numerous on the left than on the right side ; tracheal branches to the posterior membranous portion of the trachea; and some pharyngeal filaments to the Inferior constrictor of the pharynx. The Cervical Cardiac Branches, tAvo or three in number, arise from the pneumogastric, at the upper and loAver part of the neck. The superior branches are small, and communicate with the cardiac branches of the sympathetic, and Avith the great cardiac plexus. The inferior cardiac branches, one on each side, arise at the lower part of the neck, just above the first rib. On the right side, this branch passes in front of the arteria innominata, and anastomoses with the superior cardiac nerve. On the left side, it passes in front of the arch of the aorta, and anastomoses either with the superior cardiac nerve, or with the cardiac plexus. The Thoracic Cardiac Branches, on the right side, arise from the trunk of the pneumogastric, as it lies by the side of the trachea: passing inAvards, they terminate in the deep cardiac plexus. On the left side, they arise from the left recurrent laryngeal nerve. The Anterior Pulmonary Branches, two or three in number, and of small size, are distributed on the anterior aspect of the root of the lungs. They join Avith filaments from the sympathetic, and from the anterior pulmonary plexus. The Posterior Pulmonary Branches, more numerous and larger than the ante- rior, are distributed on the posterior aspect of the root of the lung: they are joined by filaments from the third and fourth thoracic ganglia of the sympathetic, and form the posterior pulmonary plexus. Branches from both plexuses accompany the ramifications of the air-tubes through the substance of the lungs. The Oesophageal Branches are given off from the pneumogastric, both above and below the pulmonary branches. The latter are the most numerous and 500 CRANIAL NERVES. largest. They form, together with branches from the opposite nerve, the oeso- phageal plexus. The Gastric Branches are the terminal filaments of the pneumogastric nerve The nerve on the right side is distributed to the posterior surface of the stomach and joins the left side of the coeliac plexus, and the splenic plexus. The nerve on the left side is distributed over the anterior surface of the stomach some filaments passing across the great cul-de-sac, and others along the lesser curvature. They unite with branches of the right nerve and sympathetic, some filaments passing through the lesser omentum to the left hepatic plexus. The Spinal Nerves. T^HE Spinal Nerves are so called, from taking their origin from the spinal cord, -*- and from being transmitted through the intervertebral foramina on either side of the spinal column. There are thirty-one pairs of spinal nerves, Avhich are arranged into the folloAving groups, corresponding to the region of the spine through Avhich they pass :— Cenlcal, ... 8 pairs. Dorsal, Lumbar, Sacral, Coccygeal, V2 5 5 1 It will be observed, that each group of nerves corresponds in number Avith the vertebrae in each region, excepting in the cervical and coccygeal. Each spinal nerve arises by tAvo roots, an anterior, or motor root, and a poste- rior, or sensitive root. Roots of the Spinal Nerves. The anterior roots arise someAvhat irregularly from a linear series of foramina, on the antero-lateral column of the spinal cord, gradually approaching toAvards the anterior median fissure as they descend. The fibres of the anterior roots pass betAveen the anterior and lateral columns, and enter the gray matter of the anterior horn, where they divide into two bundles, the larger of AA'hich is connected Avith the lateral column of the same side, while the smaller bundle passes to the anterior column of the opposite side. The component fibres of the latter bundle form part of the anterior white com- missure, and decussate Avith the roots of the nerve of the opposite side of the cord. The anterior roots are the smaller of the two, devoid of any ganglionic enlarge- ment, and their component fibrils are collected into two bundles, near the inter- vertebral foramina. The posterior roots arise, in a perfectly straight line, from the posterior lateral fissure, opposite the corresponding horn of gray matter. The fibres of the posterior roots pass directly into the gray matter of the posterior horn, at the bottom of the posterior lateral fissure, where they subdivide, some passing into the lateral and posterior columns of the same side; Avhile others enter the gray commissure, and form the transverse commissural fibres connecting these roots Avith the opposite side of the cord. The posterior roots of the.nerves are larger, and the individual filaments more numerous, and thicker, than those of the anterior. As their component fibrils pass outwards, toAvards the aperture in the dura mater, they coalesce into two bundles, receive a tubular sheath from this membrane, and enter the intervertebral ganglion which is developed upon each root. The posterior root of the first cervical nerve forms an exception to these characters. It is smaller than the anterior, has frequently no ganglion developed upon it, and, when the ganglion exists, it is often situated Avithin the dura mater. Ganglia of the Spinal Nerves. A ganglion is developed upon each posterior root of the spinal nerves. 502 SPINAL NERVES. These ganglia are of an oval form, of a reddish color, bear a proportion in size to the nerves upon which they are formed, and are placed in the interver- tebral foramina, external to the point Avhere the nerves perforate the dura mater. Each ganglion is bifid internally, where it is joined by the tAvo bundles of the posterior root, the tAvo portions being united into a single mass externally. The ganglia upon the first and second cervical nerves form an exception to these characters, being placed on the arches of the vertebrae over Avhich they pass. Tlie ganglia, also, of the sacral nerves are placed Avithin the spinal canal; and that on the coccygeal nerve, also in the canal about the middle of its posterior root. Imme- diately beyond the ganglion, the tAvo roots unite, and the trunk thus formed passes out of the intervertebral foramen, and divides into an anterior branch for the supply of the anterior part of the body; and a posterior branch, for the posterior part. Anterior Branches of the Spinal Nerves. The anterior brandies of the Spinal Nerves supply the parts of the body in front of the spine, including the limbs. They are for the most part larger than the posterior branches; this increase of size being proportioned to the larger extent of structures they are required to supply. Each branch is connected by slender filaments Avith the sympathetic. In the dorsal region, the anterior branches of the spinal nerves are completely separate from each other, and are uniform in their distribution; but in the cervical, lumbar, and sacral regions, they form intricate plexuses previous to their distribution. Posterior Branches of the Spinal Nerves. The posterior branches of the Spinal Nerves are generally smaller than the anterior: they arise from the trunk, resulting from the union of the nerves in the intervertebral foramina, and passing backAvards, divide into external and internal branches, which are distributed to the muscles and integument behind the spine. The first cervical and lower sacral nerves are exceptions to these characters. Cervical Nerves. The roots of the Cervical Nerves increase in size from the first to the fifth, and then maintain the same size to the eighth. The posterior roots bear a pro- portion to the anterior as 3 to 1, which is much greater than in any other region; the individual filaments being also much larger than those of the anterior roots. In direction, they are less oblique than those of the other spinal nerves. The first is directed a little upAvards and outwards; the second is horizontal; the others are directed obliquely downwards and outwards, the lowest being the most oblique, and consequently longer than the upper, the distance between their place of origin and their point of exit from the spinal canal, never exceeding the depth of one vertebra. The trunk of the first Cervical Nerve (Suboccipital) leaves the spinal canal, betAveen the occipital bone and the posterior arch of the atlas; the second between the posterior arch of the atlas and the lamina of the axis; and the eighth (the last), betAveen the last cervical and first dorsal vertebrae. Each nerve, at its exit from the intervertebral foramen, divides into an anterior and a posterior branch. The anterior branches of the four upper cervical nerves, form the cervical plexus. The anterior branches of the four lower cervical nerves, together with the first dorsal, form the brachial plexus. Anterior Branches of the Cervical Nerves. The anterior branch of the first, or Suboccipital Nerve, is of small size. It escapes from the vertebral canal through a groove upon the posterior arch of the atlas. In this_groove it lies beneath the vertebral artery, to the inner side of the Rectus lateralis. As it crosses the foramen in the transverse process of the CERVICAL PLEXUS. 503 atlas, it receives a filament from the sympathetic. It then descends, in front of this process, to communicate Avith an ascending branch from the second cervical nerve. Communicating filaments from this nerve join the pneumogastric, the hypo- glossal and sympathetic, and some branches are distributed to the Rectus lateralis, and the two Anterior recti. According to Valentin, it also distributes filaments to the occipito-atloid articulation, and mastoid process of the temporal bone. The anterior branch of the second Cervical Nerve escapes from the spinal canal, between the posterior arch of the atlas and the lamina of the axis, and, passing forwards on the outer side of the vertebral artery, divides in front of the Inter- transverse muscle, into an ascending branch, which joins the first cervical, and two descending branches, which join the third. The anterior branch of the third Cervical Nerve is double the size of the preced- ing. At its exit from the intervertebral foramen, it passes downwards and out- wards beneath the Sterno-mastoid, and divides 'into two branches. The ascending branch joins the anterior division of the second cervical, communicates with the sympathetic and spinal accessory nerves, and subdivides into the superficial cervi- cal, and great auricular nerves. The descending branch passes down in front of the Scalenus anticus,anastomoses with the fourth cervical nerve, and becomes con- tinuous Avith the clavicular nerves. The anterior branch of the fourth Cervical is of the same size as the preceding It receives a branch from the third, sends a communicating branch to the fifth cervical, and passing downAvards and outwards, divides into numerous filaments, which cross the posterior triangle of the neck, towards the clavicle and acromion. It usually gives a branch to the phrenic nerve whilst it is contained in the inter- transverse space. The anterior branches of the fifth, sixth, seventh, and eighth Cervical Nerves, are remarkable for their large size. They are much larger than the preceding nerves, and are all of equal size. They assist in the formation of the brachial plexus. Cervical Plexus. The cervical plexus (Fig. 2f>6) is formed by the anterior branches of the four upper cervical nerves. It is situated in front of the four upper vertebrae, resting upon the Levator anguli scapulae, and Scalenus medius muscles, and covered in by the Sterno-mastoid. Its branches may be divided into tAvo groups, superficial and* deep, Avhich may be thus aranged :— ( Superficialis colli. f Ascending < Auricularis magnus. Superficial 1 ( Occipitalis minor 1 J | ( (Sternal. [_ Descending Z Supraclavicular < Clavicular. (_ (_ Acromial. ( Communicating. r T , i Muscular. [ Internal •< ,-, Communicans noni. Deep \ (^ Phrenic. [ External / Communicating. ^ ( Muscular. Superficial Branches of the Cervical Plexus. The Superficialis Colli arises from the second and third cervical nerves, turns round the posterior border of the Sterno-mastoid about its middle, and passing obliquely forAvards behind the external jugular vein to the anterior border of that muscle, perforates the deep cervical fascia, and divides beneath the platysma into two branches, which are distributed to the anterior and lateral parts of the neck. 504 SPINAL NERVES. The ascending branch gives a filament which accompanies the external jugu- lar vein ; it then passes upAvards to the submaxillary region, and divides into branches, some of Avhich form a plexus with the cervical branches of the facial nerve beneath the Platysma; others pierce this muscle, supply it, and are distri- buted to the integument of the upper half of the neck, at its fore part, as hio*h up as the chin. The descending branch pierces the Platysma, and is distributed to the integu- ment of the side and front of the neck, as low as the sternum. This nerve is occasionally represented by tAvo or more filaments. The Auricularis Magnus is the largest of the ascending branches. It arises from the second and third cervical nerves,-winds round the posterior border of the Sterno-mastoid, and after perforating the deep fascia, ascends upon that muscle beneath the Platysma to the parotid gland, Avhere it divides into numerous branches. The facial branches pass across the parotid, and are distributed to the inte- gument of the face ; others penetrate the substance of the gland, and communicate with the facial nerve. The posterior or auricular branches ascend vertically to supply the integument of the posterior part of the pinna, communicating Avith the auricular branches of the facial and pneumogastric nerves. The mastoid branch joins the posterior auricular branch of the facial, and cross- ing the mastoid process, is distributed to the integument behind the ear. The Occipitalis Minor arises from the second cervical nerve; it curves round the posterior border of the Sterno-mastoid above the preceding, and ascends ver- tically along the posterior border of this muscle to the back part of the side of the head. Near the cranium it perforates the deep fascia, and is continued upwards along the side of the head behind the ear, supplying the integumeut and Occipito- frontalis muscle, and communicating Avith the occipitalis major, auricularis mag- nus, and posterior auricular branch of the facial. This nerve gives off an auricular branch, which supplies the Attollens aurem and the integument of the upper and back part of the auricle. This branch is occasionally derived from the great occipital nerve. The occipitalis minor varies in size ; it is occasionally double. The Descending or Supraclavicular Branches arise from the third and fourth cervical nerves ; emerging beneath the posterior border of the Sterno-mastoid, they descend in tl»c interval between this muscle and the Trapezius, and divide into branches, which are arranged, according to their position, into three groups. The inner or sternal branch crosses obliquely over the clavicular and sternal attachments of the Sterno-mastoid, and supplies the integument as far as the median line. The middle or clavicular branch crosses the clavicle, and supplies the integu- ment over the Pectoral and Deltoid muscles, communicating with the cutaneous branches of the upper intercostal nerves. Not unfrequently, the supraclavicular nerve passes through a foramen in the clavicle, at the junction of the outer with the inner two-thirds of the bone. The external or acromial branch passes obliquely across the outer surface of the Trapezius and the acromion, and supplies the integument of the upper and back part of the shoulder. Deep Branches of the Cervical Plexus. Internal Series. The Communicating Branches consist of several filaments, which pass from'the loop between the first and second cervical nerves in front of the atlas to the pneu- mogastric, hypoglossal, and sympathetic. Muscular Branches supply the Anterior recti and Rectus lateralis muscles; they proceed from the first cervical nerve, and from the loop formed between it and the second. COMMUNICANS NONI; PHRENIC. 505 The Communicans Noni (Fig. 256) consists usually of two filaments, one being derived from the second, and the other from the third cervical. These filaments descend vertically doAvnwards on the outer side of the internal jugular vein, cross in front of the vein a little beloAV the middle of the neck, and form a loop with the descendens noni in front of the sheath of the carotid vessels. Occasionally, the junction of these nerves takes place Avithin the sheath. The Phrenic Nerve (Internal Respiratory of Bell) arises from the third and fourth cervical nerves, and receives a communicating branch fron the fifth. It descends to the root of the neck, lying obliquely across the front of the Scalenus anticus, passes over the first part of the subclavian artery, between it and the subclavian vein, and, as it enters the chest, crosses the internal mammary artery, near its root. Within the chest, it descends nearly vertically in front of the root of the lung, and by the side of the pericardium, between it and the mediastinal portion of the pleura, to the Diaphragm, where it divides into branches, which separately pierce that muscle, and are distributed to its under surface. The two phrenic nerves differ in their length, and also in their relations at the upper part of the thorax. The right nerve is situated more deeply, and is shorter and more vertical in direction than the left; it lies on the outer side of the right vena innominata and superior vena cava. The left nerve is rather larger than the right, from the inclination of the heart to the left side, and from the Diaphragm being lower in this than on the opposite side. At the upper part of the thorax, it crosses in front of the arch of the aorta to the root of the lung. Each nerve supplies filaments to the pericardium and pleura, and near the chest is joined by a filament from the sympathetic; by another derived from the fifth and sixth cervical nerves ; and occasionally by one from the union of the descendens noni with the spinal nerves, Avhich, Swan states, occurs only on the left side. From the right nerve, one or two filaments pass to join in a small ganglion with phrenic branches of the solar plexus; and branches from this ganglion are distributed to the hepatic plexus, the suprarenal capsule, and inferior vena cava. From the left nerve, filaments pass to join the phrenic plexus, but without any ganglionic enlargement. Deep Branches of the Cervical Plexus. External Series. Communicating Branches. The cervical plexus communicates Avith the spinal accessory nerve, in the substance of the Sterno-mastoid muscle, in the Subocci- pital triangle, and beneath the Trapezius. Muscular Branches are distributed to the Sterno-mastoid, Levator anguli scapulae, Scalenus medius, and Trapezius. The branch for the Sterno-mastoid is derived from the second cervical; the Levator anguli scapulae receiving branches from the third ; and the Trapezius branches from the third and fourth. Posterior Branches of the Cervical Nerves. The Posterior Branches of "the cervical nerves, Avith the exception of the first tAvo, pass backAvards, and divide, behind the posterior Intertransverse muscles, into external and internal branches. The externed branches supply the muscles at the side of the neck, aIz., the Cervicalis ascendens, Transversalis colli, and Trachelo-inastoid. The external branch of the second cervical nerve is the largest; it is often joined Avith the third, and supplies the Complexus, Splenius, and Trachelo- mastoid muscles. The internal branches, the larger, are distributed differently in the upper and loAver part of the neck. Those derived from the third, fourth, and fifth nerves pass between the Semispinalis and Complexus muscles, and, having reached the 50(5 SPINAL NERVES. spinous processes, perforate the aponeurosis of the Splenius and Trapezius, and are continued outwards to the integument over the Trapezius : Avhilst those derived from the three loAvest cervical nerves are the smallest, and are placed beneath the Semispinalis, which they supply, and do not furnish any cutaneous filaments" These internal branches supply the Complexus, Semispinalis colli, Interspinales and Multifidus spinas. The posterior branches of the three first cervical nerves require a separate description. The posterior branch of the First Cervical Nerve (Suboccipital) is larger than the anterior, and escapes from the vertebral canal betAveen the occipital bone and the posterior arch of the atlas, lying behind the vertebral artery, and enters the triangular space formed by the Rectus posticus major, the Obliquus superior and Obliquus inferior. It supplies the Recti and Obliqui muscles, and the Coin- plexus. From the branch which supplies the inferior oblique a filament is given off, Avhich joins the second cervical nerve. It also occasionally gives off a cuta- neous filament, which accompanies the occipital artery, and communicates with the occipitalis major and minor nerves. The posterior division of the first cervical has no branch analogous to the external branch of the other cervical nerves. The posterior branch of the Second Cervieed Nerve is three or four times greater than the anterior branch, and the largest of all the other posterior cervical nerves. ^ It emerges from the spinal canal betAveen the posterior arch of the atlas and lamina of the axis, beloAv the Inferior oblique. It supplies this muscle, and receives a communicating filament from the first cervical. It then divides'into external and internal branches. The internal branch, called, from its size and distribution, the occipitalis major, ascends obliquely inwards between the obliquus inferior, and Complexus, and pierces the latter muscle and the Trapezius near their attachments to the cranium. It is now joined by a filament from the third cervical nerve, and ascending on the back part of the head with the occipital artery, divides into two branches, which supply the integument of the scalp as far forwards as the vertex, communicating with the occipitalis minor. It gives off an auricular branch to the back part of the ear, and muscular branches to the Complexus. The posterior branch of the Third Cervical is smaller than the preceding, but larger than the fourth ; it differs from the posterior branches of the other cervical nerves m its supplying an additional filament to the integument of the occiput, 11ns occipital branch arises from the internal or cutaneous branch beneath the Irapezms ; it pierces that muscle, and supplies the skin on the lower and back part of the head. It lies to the inner side of the occipitalis major, with which it is con- nected. J The internal branches of the posterior divisions of the three first cervical nerves are occasionally joined beneath the Complexus by communicating branches. Ihis communication has been described by Cruveilhier as the posterior cervical j) lex us. ± The Brachial Plexus (Fig. 2(i2). The brachial plexus is formed by the union of tlnf anterior branches of the four lower cervical and first dorsal nerves. It extends from the lower part of the side of the neck to the axilla, being very broad, and presenting but Tittle of a plexi- torm arrangement at its commencement, narrow opposite the clavicle, broad and presenting a more dense interlacement in the axilla, and dividing opposite the coracoid process into numerous branches for the supply of the upper limb. These nerves are all similar in size, and their mode of union in the formation of the plexus is the following. The fifth and sixth nerves unite near their exit from the spine into a common trunk ; the seventh nerve joins this trunk near the outer border of the Scalenus medius ; and the three nerves thus form one large single cord. The eighth cervical and first dorsal nerves unite beneath the Scalenus BRACHIAL PLEXUS. 507 Fasciculus fr„., b'i! Cerv.N. - CoTTi/nnnicn tin? «H Phrenic -Scapular ine of Clavicle Dorsal N. anticus into a common trunk. Thus two large trunks are formed, the upper one by the union of the fifth, sixth, and seventh cervical; and the lower one by the eighth cervical and first dorsal. These two trunks accompany the subclavian artery to the axilla, lying upon its outer side, that formed by the union of the last cervical and first dorsal being nearest to the vessel. Fig. 26*2.—Plan of the Brachial Plexus. Opposite the clavicle, and sometimes in the axilla, each of these cords gives off a fasciculus, which uniting, a third trunk is formed, so that in the centre of the axilla three cords are found, one lying on the outer side of the axillary artery, one on its inner side, and one behind. The brachial plexus com- municates Avith the cer- vical plexus by a branch from the fourth to the fifth nerve, and Avith the phrenic by a branch from the fifth cervical, which joins that nerve on the Scalenus anticus muscle: the cervical and first dor- sal nerves are also joined by filaments from the mid- dle and inferior cervical ganglia of the sympathetic, close to their exit from the intervertebral foramina. Relations. In the neck, the brachial plexus lies at first betAveen the Scalenus anticus and Scalenus medius muscles, and then above and to the outer side of the subclavian artery; it then passes beneath the clavicle and Subclavius muscle, lying upon the first serration of the Serratus magnus and Subscapularis muscles. In the axilla, it is placed on the outer side of the first portion of the axillary artery; it surrounds the artery in the second part of its course, one cord lying upon the outer side of that vessel, one on the inner side, and one behind it; and at the lower part of the axillary space gives off its terminal branches to the upper extremity. Branches. The branches of the brachial plexus may be arranged into two groups, viz., those given off above the clavicle, and those below that bone. Branches above the Clavicle. Communicating. Muscular. Posterior thoracic. Suprascapular. The Communicating Branch Avith the phrenic is derived from the fifth cervical nerve; it joins the phrenic on the Scalenus anticus muscle. The Muscular Brandies supply the Longus colli, Scaleni, Rhomboidei, and Subclavius muscles. Those for the Scaleni and Longus colli arise from the loAver cervical nerves at their exit from the intervertebral foramina. The rhomboid branch arises from the fifth cervical, pierces the Scalenus medius, and passes beneath the Levator anguli scapulae, Avhich it occasionally supplies, to the Rhom- boid muscles. The subclavian branch is a small filament, Avhich arises from the 508 SPINAL NERVES. trunk formed by the junction of the fifth and sixth cervical nerves ; it descends in front of the subclavian artery to the Subclavius muscle, and is usually connected by a filament Avith the phrenic nerve. The Posterior Thoracic Nerve (long thoracic, external respiratory of Bell) supplies the Serratus magnus, and is remarkable for the length of its course. It arises by two roots, from the fifth and sixth cervical nerves, immediately after their exit from the intervertebral foramina. These unite in the substance of the Scalenus medius muscle, and, after emerging from it, the nerve passes doAvn be- hind the brachial plexus and the axillary vessels, resting on the outer surface of the Serratus magnus. It extends along the side of the chest to the lower border of this muscle, and supplies it Avith numerous filaments. The Suprascapular Nerve arises from the cord formed by the fifth, sixth, and seA'enth cervical nerves ; passing obliquely outwards beneath the Trapezius it enters the supraspinous fossa, through the notch in the upper border of the scapula ; and, passing beneath the Supraspinatus muscle, curves in front of the spine of the scapula to the infraspinous fossa. In the supraspinous fossa it gives off two branches to the Supraspinatus muscle, and an articular filament to the shoulder joint; and in the infraspinous fossa, it gives off two branches to the Infraspinatus muscle, besides some filaments to the shoulder joint and scapula. Branches beloav the Clavicle. To chest, . Anterior thoracic. To shoulder, \ ^u JSC<1PU ai- 7 ( Circumflex. Musculo-cutaneous. Internal cutaneous. Lesser internal cutaneous. Median. Ulnar. Musculo-spiral. The branches given off below the clavicle are derived from the three cords of the brachial plexus in the folloAving manner:— From the outer cord, arise the external of the two anterior thoracic nerves, the musculo-cutaneous nerve, and the outer head of the median. From the inner cord, arise the internal of the two anterior thoracic nerves, the internal cutaneous, the lesser internal cutaneous (nerve of Wrisberg), the ulnar, and inner head of the median. From the posterior cord, arises the subscapular; and it then subdivides into the musculo-spiral and circumflex nerves. The Anterior Thoracic Nerves, two in number, supply the Pectoral muscles. The external, or superficial branch, the larger of the two, arises from the outer cordof the brachial plexus, passes inAvards, across the axillary artery and vein, and is distributed to the under surface of the Pectoralis major. It sends down a communicating filament to join the internal branch. The internal^ or deep branch, arises from the inner cord, and passes upwards between the axillary artery and vein (sometimes perforates the vein), and joins with the filament from the superficial branch. From the loop thus formed, branches are distributed to the under surface of the Pectoralis minor and maior muscles. The Subscapular Nerves are three in number, and supply the Subscapularis, Teres major, and Latissimus dorsi muscles. The upper subscapular nerve, the smallest, enters the upper part of the Subscapularis muscle. The lower subscapular nerve enters the axillary border of the Subscapularis, and terminates in the Teres major. The latter muscle is sometimes supplied by a separate branch. To arm, fore- arm, and hand. CUTANEOUS NERVES OF THE FOREARM. 509 263.—Cutaneous Nerves of Right Upper Extremity. Anterior View. The long subscapular, the largest of the three, descends along the lower border of the Subscapularis to the Latissimus dorsi, through Avhich it may be traced as far as its Ioavci* border. The Circumflex Nerve supplies some of the muscles, and the integument of the shoulder, and the shoulder joint. It arises from the posterior cord of the brachial plexus, in common with the musculo-spiral nerve. It passes down behind the axillary artery, and in front of the subscapularis; and, at the loAver border of this muscle, passes backwards, and divides into tAvo branches. The superior branch winds round the neck of the humerus, beneath the Del- toid, with the posterior circumflex vessels, as far as the anterior border of this muscle, supplying it, and giving off cutaneous branches, Avhich pierce it to ramify in the integument covering its loAver part. The inferior branch, at its origin, dis- tributes filaments to the Teres minor and back part of the Deltoid muscles; upon the filament to the former muscle a gan- gliform enlargement usually exists. The nerve then pierces the deep fascia, and supplies the integument over the lower two-thirds of the posterior surface of the Deltoid, as Avell as that covering the long head of the Triceps. The circumflex nerve, before its divi- sion, gives off an articular filament, Avhich enters the shoulder joint below the Sub- scapularis. The Musculo-cutaneous Nerve (ex- ternal cutaneous, perforans Gasserii) sup- plies some of the muscles of the arm, and the integument of the forearm. It arises from the outer cord of the brachial plexus, opposite the loAver border of the Pecto- ralis minor. It then perforates the Coraco- brachialis muscle, and passes obliquely between the Biceps and Brachialis anti- cus, to the outer side of the arm, a little above the elbow, where it perforates the deep fascia and becomes cutaneous. This nerve, in its course through the arm, sup- plies the Coraco-brachialis, Biceps, and Brachialis anticus muscles, besides some filaments to the elbow joint and humerus. The cutaneous portion of the nerve passes behind the median cephalic vein, and divides, opposite the elboAv joint, into an anterior and a posterior branch. The anterior branch descends along the radial border of the forearm to the wrist. It is here placed in front of the radial artery, and, piercing the deep fascia, accompanies that vessel to the back of the Avrist. It communicates with a branch from the radial nerve, and distributes filaments to the integument of the ball of the thumb, and to the wrist joint. 510 SPINAL NERVES. Fig. 264.—Cutaneous Nerves of Right Upper Extremity. Posterior View. The posterior branch is given off about the middle of the forearm, and passes downAvards along the back part of its radial side, to the wrist. It supplies the integument of the lower third of the forearm, communicating with the radial nerve, and the external cutaneous branch of the musculo-spiral. The Internal Cutaneous Nerve is one of the smallest branches of the brachial plexus. It arises from the inner cord, in common with the ulnar and internal head of the median, and, at its commence- ment, is placed on the inner side of the brachial artery. It passes doAvn the inner side of the arm, pierces the deep fascia with the basilic vein, about the middle of the limb, and becoming cutaneous, di- vides into two branches. This nerve gives off, near the axilla, a cutaneous filament, which pierces the fascia, and supplies the integument cover- ing the Biceps muscle, nearly as far as the elbow. This filament lies a little ex- ternal to the common trunk from Avhich it arises. The anterior branch, the larger of the two, passes in front of, occasionally be- hind, the median basilic vein. It then descends on the anterior surface of the ulnar side of the forearm, distributing filaments to the integument as far as the Avrist, and communicating Avith a cuta- neous branch of the ulnar nerve. The posterior branch, passes obliquely downwards on the inner side of the basilic vein, Avinds over the internal condyle of the humerus to the back of the forearm, and descends, on the posterior surface of its ulnar side, to a little beloAV the middle, distributing filaments to the integument. It anastomoses above the elboAv, with the lesser internal cutaneous, and aboA'e the wrist, with the dorsal branch of the ulnar nerve (Swan). The Lesser Internal Cutaneous Nerve (nerve of Wrisberg) is distributed to the integument on the inner side of the arm. It is the smallest of the branches of the brachial plexus, and usually arises from the inner cord, Avith the internal cutaneous and ulnar nerves. It passes through the axillary space, at first lying beneath, and then on the inner side, of the axillary vein, and communicates with the intercosto-humeral nerve. It then descends along the inner side of the bra- chial artery, to the middle of the arm, where it pierces the deep fascia, and is distributed to the integument of the back part of the lower third of the arm, extending as far as the elboAv, where some filaments are lost in the integument in MEDIAN. 511 front of the inner condyle, and others over the olecranon. It communicates Avith the inner branch of the internal cutanous nerve. In some cases, the nerve of Wrisberg and intercosto-humeral are connected by two or three filaments, Avhich form a kind of plexus at the back part of the axilla. In other cases, the intercosto-humeral is of large size, and takes the place of the nerve of Wrisberg, receiving merely a filament of communlc ition from the brachial plexus, which represents this nerve. In other cases, this filament is wanting, the place of the nerve of Wrisberg being supplied entirely from the intercosto- humeral. The Median Nerve (Fig. 265) has received its name from the course it takes along the middle line of the arm and forearm to the hand, lying betAveen the ulnar and musculo-spiral and radial nerves. It arises by two roots, one from the outer, and one from the inner cord of the brachial plexus; these embrace the loAver part of the axillary artery, uniting either in front or on the outer side of that « vessel. As it descends through the arm, it lies at first on the outer side of the brachial artery, crosses that vessel in the middle of its course, usually in front, but occasionally behind it, and lies on its inner side to the bend of the elbow, where it is placed beneath the bicipital fascia, and is separated from the elboAv joint by the Brachialis anticus. In the forearm, it passes between the two heads of the Pronator radii teres, and descends beneath the Flexor sublimis, to within tAvo inches above the annular ligament, where it becomes more superficial, lying betAveen the Flexor sublimis and Flexor carpi radialis, covered by the integument and fascia. It then passes beneath the annular ligament into the hand. Branches. No branches are given off from the median nerve in the arm. In the forearm, its branches are, muscular, anterior interosseous, and palmar cutaneous. The muscular branches supply all the superficial layer of muscles on the ante- rior surface of the forearm, except the Flexor carpi ulnaris. These branches are derived from the nerve near the elbow. The branch furnished to the Pronator radii teres often arises above the joint. The anterior interosseous supplies the deep muscles on the anterior surface of the forearm. It accompanies the anterior interosseous artery along the inter- osseous membrane, in the interval betAveen the Flexor longus pollicis and Flexor profundus digitorum muscles, both of which it supplies, and terminates below in the Pronator quadratus. The palmar cutaneous branch arises from the median nerve at the lower part of the forearm. It pierces the fascia above the annular ligament, and di- vides into tAvo branches ; the outer one supplies the skin over the ball of the thumb, and communicates Avith the external cutaneous nerve ; the inner one sup- plies the integument of the palm of the hand, anastomosing with the cutaneous branch of the ulnar. Both nerves cross the annular ligament previous to their distribution. In the palm of the hand, the median nerve is covered by the integument and palmar fascia, and rests upon the tendons of the Flexor muscles. In this situation it becomes enlarged, someAvhat flattened, of a reddish color, and divides into two branches. Of these, the external one supplies a muscular branch to some of the muscles of the thumb, and digital branches to the thumb and index finger ; the internal branch supplying digital branches to the middle finger and part of the index and ring fingers. The branch to the muscles of the thumb is a short nerve, which subdivides to supply the Abductor, Opponens, and outer head of the Flexor brevis pollicis mus- cles ; the remaining muscles of this group being supplied by the ulnar nerve. The digital branches are five in number. The first and second pass along the borders of the thumb, the most external one communicating with branches of the radial nerve. The third passes along the radial side of the index finger, and supplies the first Lumbrical muscle. The fourth subdivides to supply the adjacent 512 SPINAL NERVES. Fig. 265.—Nerves of the Left Upper Extremity. Front View. 1 nlerior 2r/iorix,cie> Infsrna? 'A.Jtterlor Thonetetc \* \ Maseulo- "" Cutanea as usrufc Spiral Posfe j~i'or In teroxse ous Anterior Tnierosseotzs ULNAR. 513 sides of the index and middle fingers, and sends a branch to the second Lumbri- cal muscle. The fifth supplies the adjacent sides of the middle and ring fingers, and communicates with a branch from the ulnar nerve. Each digital nerve, opposite the base of the first phalanx, gives off a dorsal branch, which joins the dorsal digital nerve, and runs along the side of the dorsum of the finger, ending in the integument over the last phalanx. At the end of the finger, the digital nerve divides into a palmar and a dorsal branch; the former supplies the extremity of the finger, and the latter ramifies around and beneath the nail. The digital nerves, as they run along the fingers, are placed superficial to the digital arteries. The Ulnar Nerve is placed along the inner or ulnar side of the upper limb, and is distributed to the muscles and integument of the forearm and hand. It is smaller than the median, behind which it is placed, diverging from it in its course doAvn the arm. It arises from the inner cord of the brachial plexus, in common with the internal head of the median and the internal cutaneous nerves. At its commencement, it lies at the inner side of the axillary artery, and holds the same relation with the brachial artery to the middle of the arm. From this point,*it runs obliquely across the internal head of the Triceps, pierces the internal intermuscular septum, and descends to the groove between the internal condyle and olecranon, accompanied by the inferior profunda artery. At the elbow, it rests upon the inner condyle, and passes into the forearm between the tAvo heads of the Flexor carpi ulnaris. In the forearm, it descends in a perfectly straight course along its ulnar side, lying upon the Flexor profundis digitorum, its upper half being covered by the Flexor carpi ulnaris, its loAver half lying on the outer side of this muscle, covered by the integument and fascia. The ulnar artery in the upper part of its course, is separated from the ulnar nerve by a considerable inverval; in the lower half of its coui^e, the nerve lies to its inner side. At the wrist, the ulnar nerve crosses the annular ligament on the outer side of the pisiform bone, a little behind the ulnar artery, and immediately beyond this bone divides into tAvo branches, superficial and deep palmar. The branches of the ulnar nerve are f Articular (elbow). Muscular. T b H / Superficial palmar. In forearm < Cutaneous. \ Deep palmar. Dorsal branch. Articular (wrist). The Articular branches distributed to the elboAv joint consist of several small filaments. They arise from the nerve as it lies in the groove between the inner condyle and olecranon. The Muscular branches are tAvo in number; one supplying the Flexor carpi ulnaris; the other, the inner half of the Flexor profundus digitorum. They arise from the trunk of the nerve near the elboAv. The Cutaneous branch arises from the ulnar nerve about the middle of the fore- arm, and divides into a superficial and deep branch. The superficial branch (frequently absent) pierces the deep fascia near the Avrist, and is distributed to the integument, communicating with a branch of the internal cutaneous nerve. The deep branch lies on the ulnar artery, AAdiich it accompanies to the hand, some filaments entwining around the vessel, Avhich end in the integument of the palm, communicating AA'ith branches of the median nerve. The Dorsal cutaneous branch arises about two inches above the wrist; it passes backwards beneath the Flexor carpi ulnaris, perforates the deep fascia, and, run- ning along the ulnar side of the Avrist and hand, supplies the inner side of the little finger, and the adjoining sides of the little and ring fingers; it also sends a com- municating filament to that branch of the radial nerve Avhich supplies the adjoin- ing sides of the middle and ring fingers. 35 511 SPINAL NERVES. Articular filaments to the wrist are also supplied by the ulnar nerve. The Superficial palmar branch supplies the Palmaris brevis, and the integument on the inner side of the hand, and terminates in tAvo digital branches, Avhich are distributed, one to the ulnar side of the little finger, the other to the adjoining sides of the little and ring fingers, the latter communicating -with a branch from the median. The Deep palmar branch passes betAveen the Abductor and Flexor brevis minimi.digiti muscles, and follows the course of the deep palmar arch beneath the flexor tendons. At Fig. 266.—The Suprascapular, Circumflex, and Musculo-spiral Nerves. Suprascapular Circumflex its origin, it supplies the muscles of the little finger. the deep part Paste ricr-Ioitercaseous As it crosses of the hand branches to seous space, Dorsal and it sends tAvo each interos- one for the one for the Palmar interosseous mus- cle, the branches to the second and third Palmar interossei supplying fila- ments to the two inner Lumbrical muscles. At its termination betAveen the thumb and index finger, it supplies the Adductor pol- licis and the inner head of the Flexor brevis pollicis. The Musculo-spiral Nerve (Fig. 266), the largest branch of the brachial plexus, supplies the mus- cles of the back part of the arm and forearm, and the integument of the same parts, as Avell as that of the hand. It arises from the posterior cord of the brachial plexus by a com- mon trunk with the cir- cumflex nerve. At its commencement, it is placed behind the axillary and upper part of the brachial arteries, passing down in front of the tendons of the Latissimus dorsi and Teres major. It 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 mus- cle. At the outer side of the arm, it descends be- tween the Brachialis an- ticus and Supinator longus MUSCULO-SPIRAL. 515 to the front of the external condyle, Avhere it divides into the radial and posterior interosseous nerves. .The branches of the musculo-spiral nenTe are:— Muscular. Radial. Cutaneous. Posterior interosseous. The Muscular branches supply the Triceps, Anconeus, Supinator longus, Extensor carpi radialis longior, and Brachialis anticus. These branches are derived from the nerve, at the inner side, back part, and outer side of the arm. The internal muscular branches supply the inner and middle heads of the Triceps muscle. That to the inner head of the Triceps is a long, slender filament, which lies close to the ulnar nerve, as far as the lower third of the arm. The posterior muscular branch, of large size, arises from the nerve in the groove between the Triceps and the humerus. It divides into branches which supply the outer head of the Triceps and Anconeus muscles. The branch for the latter muscle is a long, slender filament, which descends in the substance of the Triceps to the Anconeus. The external muscular branches supply the Supinator longus, Extensor carpi radialis longior, and Brachialis anticus. The Cutaneous branches are three in number, one internal, and two external. The internal cutaneous branch arises in the axillary space, with the inner mus- cular branch. It is of small size, and passes across the axilla to the inner side of the arm, supplying the integument on its posterior aspect nearly as far as the olecranon. The two external cutaneous branches T»erforate the outer head of the Triceps, at its attachment to the humerus. The upper and smaller one folloAvs the course of the cephalic vein to the front of the elboAv, supplying the integument of the lower half of the upper arm on its anterior aspect. The lower branch pierces the deep fascia beloAV the insertion of the Deltoid, and passes down along the outer side of the arm and elbow, and along the radial side of the forearm to the wrist, supplying the integument in its course, and joining, near its termination, with a branch of the external cutaneous nerve. The Radial Nerve passes along the front of the radial side of the forearm, to the commencement of its loAver third. It lies at first a little to the outer side of the radial artery, concealed beneath the Supinator longus. In the middle third of the forearm, it lies beneath the same muscle, in close relation with the outer side of that vessel. It quits the artery about three inches above the Avrist, passes be- neath the tendon of the Supinator longus, and, piercing the deep fascia at the outer border of the forearm, divides into tAvo branches. The external branch, the smaller of the two, supplies the integument of the radial side, and ball of the thumb, joining Avith the posterior branch of the external cutaneous nerve. The internal branch communicates, above the wrist, with a branch from the ex- ternal cutaneous, and, on the back of the hand, forms an arch with the dorsal branch of the ulnar nerve. It then divides into digital nerves, which supply, the first, the ulnar side of the thumb; the second, the radial side of the index finger; the third, the adjoining sides of the index and middle fingers; and the fourth, the adjacent borders of the middle and ring fingers. The latter nerve communicates Avith a filament from the dorsal branch of the ulnar nerve. The Posterior Interosseous Nerve pierces the Supinator breAris, winds to the back of the forearm, in the substance of this muscle, and, emerging from its loAver border, passes down betAveen the superficial and deep layer of muscles, to the middle of the forearm. Considerably diminished in size, it descends on the interosseous membrane, beneath the extensor secundi internodii pollicis, to the back of the carpus, Avhere it presents a gangliform enlargement, from AA'hich filaments are dis- 516 SPINAL NERVES. tributed to the ligaments and articulations of the carpus. It supplies all the mus- cles of the radial and posterior brachial regions, excepting the Anconeus, Supinator longus, and Extensor carpi radialis longior. Dorsal Nerves. The Dorsal Nerves are twelve in number on each side. The first appears between the first and second dorsal vertebrae, and the last betAveen the last dorsal and first lumbar. The roots of origin of the dorsal nerves are feAV in number, of small size, and vary but slightly from the second to the last. Both roots are very slender ; the posterior ones exceeding in thickness those of the anterior only in a slight degree. These roots gradually increase in length from above downwards, and remain in contact with the spinal cord for a distance equal to the height of at least two ver- tebrse, in the lower part of the dorsal region. They then join in the intervertebral foramen, and, at their exit, divide into two branches, a posterior, or dorsal, and an anterior, or intercostal branch. The first and last dorsal nerves are exceptions to these characters. The Posterior primary branches of the Dorsal Nerves, Avhich are smaller than the intercostal, pass backwards between the transverse processes, and divide into external and internal branches. The external branches increase in size from above doAvnwards. They pass through the Longissimus dorsi, corresponding to the cellular interval betAveen it and the Sacro-lumbalis, supplying these muscles, as well as those by which they are continued upwards to the head, and the Levatores costarum; the five or six lower ones giA'ing off cutaneous filaments. The internal branches of the six upper nerves pass inwards to the interval be- tween the Multifidus spinas and Semispinalis dorsi muscles, which they supply; then, piercing the origin of the Rhomboideus and Trapezius, become cutaneous by the side of the spinous processes. The internal branches of the six lower nerves are distributed to the Multifidus spinae, without giving off any cutaneous filaments. The cutaneous branches of the dorsal nerves are twelve in number, the six upper being derived from the internal branches, and the six loAver from the external branches. The former pierce the Rhomboid and Trapezius muscles, close to the spinous processes, and ramify in the integument. They are frequently furnished with gangliform enlargements. The six lower cutaneous branches pierce the Serratus posticus inferior, and Latissimus dorsi, in a line with the angles of the ribs. Intercostal Nerves. The Intercostal Nerves (anterior primary branches of the dorsal nerves) are twelve in number on each side. They are distributed to the parietes of the thorax and abdomen, separately from each other, without being joined in a plexus, in which respect they differ from all the other spinal nerves. Each nerve is con- nected with the adjoining ganglia of the sympathetic by one or two filaments. The intercostal nerves may be divided into two sets, from the difference they pre- sent in their distribution. The six upper, with the exception of the first, are limited in their distribution to the parietes of the chest. The six lower supply the parietes of the chest and abdomen. Upper Intercostal Nerves. The Upper Intercostal Nerves pass forAvards in the intercostal spaces with the intercostal vessels, lying below the veins and artery. At the back of the chest, they lie between the pleura and the External intercostal muscle, but are soon placed between the two planes of Intercostal muscles as far as the costal car- INTERCOSTAL. 517 tilages, where they lie between the pleura and the Internal intercostal muscles. Near the sternum, they cross the internal mammary artery, and Triangularis sterni, pierce the Internal intercostal and Pectoralis major muscles, and supply the integument of the mamma and front of the chest, forming the anterior cutaneous nerves of the thorax ; that from the second nerve becoming joined Avith the supraclavicular nerves. Branches. Numerous slender muscular filaments supply the Intercostal and Triangularis sterni muscles. Some of these branches, at the front of the chest, cross the costal cartilages from one to another intercostal space. Lateral Cutaneous Nerves. These are derived from the intercostal nerves, midway between the vertebras and sternum, pierce the External intercostal and Serratus magnus muscles, and divide into two branches, anterior and posterior. The anterior branches are reflected forAvards to the side and forepart of the chest, supplying the integument of the chest and mamma, and the upper digita- tions of the External oblique. The posterior branches are reflected backwards, to supply the integument over the scapula and Latissimus dorsi. The first intercostal nerve has no lateral cutaneous branch. The lateral cuta- neous branch of the second intercostal nerve is of large size, and named from its origin and distribution, the intercosto-humeral nerve. The Intercosto-humeral Nerve is of large size. It pierces the External inter- costal muscle, crosses the axillary space to the inner side of the arm, and joins with a filament from the nerve of Wrisberg. It then pierces the fascia, and sup- plies the integument of the upper half of the inner and posterior side of the arm, communicating with the internal cutaneous branch of the musculo-spiral nerve. The size of this nerve is in inverse proportion to the size of the other cutaneous nerves, especially the nerve of Wrisberg. Lower Intercostal Nerves. The Loiver Lntercostal Nerves (excepting the last) have the same arrangement as the upper ones as far as the anterior extremities of the intercostal spaces, Avhere they pass behind the costal cartilages, and betAveen the Internal oblique and Transversalis muscles, to the sheath of the rectus, which they perforate. They supply the Rectus muscle, and terminate in branches which become subcutaneous near the linea alba (anterior cutaneous nerves of the abdomen), and supply the inte- gument in front of the abdomen, being directed outwards to the lateral cutaneous nerves. The lower intercostal nerves supply the Intercostal and Abdominal mus- cles, and about the middle of their course give off lateral cutaneous branches, Avhich pierce the External intercostal and External oblique muscles, and are distributed to the integument of the abdomen, the anterior branches passing nearly as far forwards as the margin of the Rectus, the posterior branches passing to supply the skin over the Latissimus dorsi, where they join the dorsal cutaneous nerves. Peculiar Dorsal Nerves. First Dorsal Nerve. Its roots of origin are similar to those of a cervical nerve. Its posterior or dorsal branch resembles, in its mode of distribution, the dorsal branches of the cervical nerves. Its anterior branch enters almost Avholly into the formation of the brachial plexus, giving off, before it leaves the thorax, a small intercostal branch, Avhich runs along the first intercostal space, and terminates on the front of the chest, by forming the first anterior cutaneous nerve of the thorax. The first intercostal nerve gives off no lateral cutaneous branch. The Last Dorsal is larger than the other dorsal nerves. Its anterior branch runs along the loAver border of the last rib in front of the Quadratus lumborum, perforates the aponeurosis of the Transversalis, and passes forAvards between it and the internal oblique, to be distributed in the same manner as the preceding nerves. It communicates with the ilio-hypogastric branch of the lumbar plexus, 518 SPINAL NERVES. and is occasionally connected Avith the first lumbar nerve by a slender branch the dorsi-lumbar nerve, Avhich descends in the substance of the Quadratus lumborum. The lateral cutaneous branch of the last dorsal is remarkable for its laro*e size ; it perforates the Internal and External oblique muscles, passes doAvmvards over the crest of the ilium, and is distributed to the integument of the front of the hip, some of its filaments extending as Ioav doAvn as the trochanter major. Lumbar Nerves. The Lumbar Nerves are five in number on each side ; the first appears between the first and second lumbar vertebra*, and the last betAveen the last lumbar and the base of the sacrum. The roots of the lumbar nerves are the largest, and their filaments the most numerous, of all the spinal nerves, and they are closely aggregated together upon the lower -end of the cord. The anterior roots are smaller, but there is not the same disproportion betAveen them and the posterior roots as in the cervical nerves. The roots of these nerves have a vertical direction, and are of consider- able length, more especially the loAver ones, as the spinal cord does not extend beyond the first lumbar vertebra. The roots become joined in the intervertebral foramina, and at their exit divide into tAvo branches, anterior and posterior. The Posterior branches of the lumbar nerves diminish in size from above down- wards ; they pass backAvards betAveen the transverse processes, and divide into external and internal branches. The external branches supply the Erector spinge and Intertransverse muscles. From the three upper branches cutaneous nerves are derived, Avhich pierce the Sacro-lumbalis and Latissimus dorsi muscles, and descend over the back part of the crest of the ilium to be distributed to the integument of the gluteal region, some of the filaments passing as far as the trochanter major. The internal branches, the smaller, pass inwards close to the articular processes of the vertebrae, and supply the Multifidus spina? and Interspinales muscles. The Anterior branches of the lumbar nerves increase in size from above down- Avards. At their origin, they communicate with the lumbar ganglia of the sympa- thetic by long slender filaments, which accompany the lumbar arteries around the sides of the bodies of the vertebrae, beneath the Psoas muscle. The nerves pass obliquely outwards behind the Psoas magnus, or between its fasciculi, distributing filaments to it and the Quadratus lumborum. The anterior branches of the four upper nerves are connected together in this situation by anastomotic loops, and form the lumbar plexus. The anterior branch of the fifth lumbar, joined with a branch from the fourth, descends across the base of the sacrum to join the ante- rior branch of the first sacral nerve, and assist in the formation of the sacral plexus. The cord resulting from the union of these two nerves is called the lumbosacral nerve. Lumbar Plexus. The Lumbar Plexus is formed by the loops of communication between the anterior branches of the four upper lumbar nerves. The plexus is narrow above, and occasionally connected with the last dorsal by a slender branch, the dorsi- lumbar nerve ; it is broad below, where it is joined to the sacral plexus by the lumbo-sacral It is situated in the substance of the Psoas muscle near its poste- rior part, in front of the transverse processes of the lumbar vertebra. " Ihe mode in which the plexus is formed is the following. The first lumbar nerve gives off the ilio-hypogastric and ilio-inguinal nerves, and a communicating branch to the second. The second gives off the external cutaneous and genito- crural, and a communicating branch to the third nerve. The third nerve gives a descending filament to the fourth, and divides into tAvo branches, which assist m forming the anterior crural and obturator nerves. The fourth nerve completes the formation of the anterior crural, and the obturator ; furnishes part of the accessory obturator, and gives off a communicating branch to the fifth lumbar. LUMBAR PLEXUS. 519 The branches of the lumbar plexus are the Ilio-hypogastric. Obturator. Ilio-inguinal. Accessory obturator. Genito-crural. Anterior crural. External cutaneous. These branches may be divided into two groups, according to their mode of distribution. One group, including the ilio-hypogastric, ilio-inguinal, and part of the genito-crural nerves, supplies the loAver part of the parietes of the abdo- men ; the other group, Avhich includes the remaining nerves, supplies the fore- part of the thigh and inner side of the leg. Fig. 267.—The Lumbar Plexus and its Branches. The Ilio-hypogastric branch {superior musculo-cutaneous) arises from the first lumbar nerve. It pierces the outer border of the Psoas muscle at its upper part, and crosses obliquely over the Quadratus lumborum to the crest of the ilium. It then perforates the Transversalis muscle, and divides betAveen it and the Internal oblique into two branches, iliac and hypogastric. The iliac branch pierces the Internal and External oblique muscles imme- diately above the crest of the ilium, and is distributed to the integument of the gluteal region, behind the lateral cutaneous branch of the last dorsal nerve (Fig. 270). The size of this nerve bears an inverse proportion to that of the cutaneous branch of the last dorsal nerve. 520 SPINAL NERVES. The hypogastric branch continues onwards betAveen the Internal oblique and Transversalis muscles. It first pierces the Internal oblique, and near the middle line perforates the External oblique, and is distributed to the integument covering the hypogastric region. The Ilio-inguinal branch (inferior musculo-cutaneous), smaller than the preceding, also arises from the first lumbar nerve. It pierces the outer border of the Psoas just beloAv the ilio-hypogastric, and passes obliquely doAvnwards and outAvards across the Quadratus lumborum and Iliacus muscles, perforates the Transversalis, and communicates Avith the ilio-hypogastric nerve betAveen that muscle and the Internal oblique, near the forepart of the crest of the ilium. The nerve then pierces the Internal oblique, distributing filaments to it, and accom- panying the spermatic cord, escapes at the external abdominal ring, and is distri- buted to the integument of the scrotum and upper and inner part of the thigh in the male, and to the labium in the female. The size of this nerve is in inverse proportion to that of the ilio-hypogastric. Occasionally it is very small, and ends by joining it; in such cases, a branch from the ilio-hypogastric takes the place of that nerve, or the nerve may be altogether absent. The Genito-crural Nerve arises from the second lumbar, and by a feAV fibres from the cord of communication betAveen it and the first. It passes obliquely through the substance of the Psoas, descends on its surface to near Poupart's ligament, and divides into a genital and a crural branch. The genital branch descends on the external iliac artery, sending a feAV fila- ments around that vessel; it then pierces the fascia transversalis, and passing through the internal abdominal ring, descends along ,the back part of the sper- matic cord to the scrotum, and supplies, in the male, the Cremaster muscle. In the female, it accompanies the round ligament, and is lost upon it. The crural branch passes along the inner margin of the Psoas muscle, beneath Poupart's ligament, into the thigh, where it pierces the fascia lata, and is distri- buted to the integument of the upper and anterior aspect of the thigh, communi- cating with the middle cutaneous nerve. A few filaments from this nerve may be traced on to the femoral artery; they are derived from the nerve as it passes beneath Poupart's ligament. The External Cutaneous Nerve arises from the second lumbar, or from the loop betAveen it and the third. It perforates the outer border of the Psoas muscle about its middle, and crosses the Iliacus muscle obliquely, to the notch imme- diately beneath the anterior superior spine of the ilium, Avhere it passes beneath Poupart's ligament into the thigh, and divides into tAvo branches of nearly equal size, anterior and posterior. The anterior branch descends in an aponeurotic canal formed in the fascia lata, becomes superficial about four inches beloAV Poupart's ligament, and divides into branches, Avhich are distributed to the integument along the anterior and outer part of the thigh, as far down as the knee. This nerve occasionally com- municates with the long saphenous nerve. The posterior branch pierces the fascia lata, and subdivides into branches which pass across the outer and posterior surface of the thigh, supplying the integument in this region as far as the middle of the thigh. The Obturator Nerve supplies the Obturator externus and Adductor muscles of the thigh, the articulations of the hip and knee, and occasionally the integu- ment of the thigh and leg. It -arises by two branches : one from the third, the other from the fourth lumbar nerve. It descends through the inner fibres of the Psoas muscle, and emerges from its inner border near the brim of the pelvis; it then runs along the lateral wall of the pelvis, above the obturator vessels, to the upper part of the obturator foramen, where it enters the thigh, and divides into an anterior and a posterior branch, separated by the Adductor brevis muscle. The anterior branch passes down in front of the Adductor brevis, being covered by the Pectineus and Adductor longus; and, at the lower border of the latter muscle, -communicates with the internal cutaneous and internal saphenous CUTANEOUS NERVES OF LOWER EXTREMITY. 521 Fig. 208.—Cutaneous Nerves of Lower Extremity. Front View. Fig. 269.—Nerves of the Lower Extremity. Front View. F-cternrr/ Cutun *.,,„,« ^)l. if,,/, Ac,,o . Ant. Tibial U^ interior Crural 522 SPINAL NERVES. nerves, forming a kind of plexus. It then descends upon the femoral artery, upon which it is finally distributed. This neiwe, near the Obturator foramen, gives off an articular branch to the hip joint. Behind the Pectineus, it distributes muscular branches to the Adduc- tor longus and Gracilis, and occasionally to the Adductor brevis and Pectineus, and receives a communicating branch from the accessory obturator nerve. Occasionally this communicating branch is continued down, as a cutaneous branch, to the thigh and leg; emerging from the lower border of the Adductor longus, it descends along the posterior margin of the Sartorius to the inner side of the knee, Avhere it pierces the deep fascia, communicates Avith the long saphenous nerve, and is distributed to the integument of the inner side of the leg, as low doAvn as its middle. When this branch is small, its place is supplied by the internal cuta- neous nerve. The posterior branch of the obturator nerve pierces the Obturator externus, and passes behind the Adductor brevis to the front of the Adductor magnus, Avhere it divides into numerous muscular branches, Avhich supply the Obturator externus, the Adductor magnus, and occasionally the Adductor brevis. The articular branch for the knee joint perforates the loAver part of the Adductor magnus, and enters the upper part of the popliteal space ; descending upon the popliteal artery, as far as the back part of the knee joint, it perforates the posterior ligament, and is distributed to the synovial membrane. It gives filaments to the artery in its course. The Accessory Obturator Nerve is of small size, and arises either from the obturator nerve near its origin, or by separate filaments from the third and fourth lumbar nerves. It descends along the inner border of the Psoas muscle, crosses the body of the pubes, and passes beneath the Pectineus muscle, where it divides into numerous branches. One of these supplies the Pectineus, penetrating its under surface ; another is distributed to the hip joint; while a third communicates with the anterior branch of the obturator nerve. This branch, Avhen of large size, is prolonged (as already mentioned), as a cutaneous branch, to the leg. The accessory obturator nerve is not constantly found; when absent, the hip joint receives branches from the obturator nerve. Occasionally it is very small, and becomes lost in the capsule of the hip joint. The Anterior Crural Nerve is the largest branch of the lumbar plexus. It .supplies muscular branches to the Iliacus, Pectineus, and all the muscles on the front of the thigh, excepting the Tensor vaginae femoris ; cutaneous filaments to the front and inner side of the thigh, and to the leg and foot; and articular branches to the knee. It arises from the third and fourth lumbar nerves, receiving also a fasciculus from the second. It descends through the fibres of the Psoas muscle, emerging from it at the lower part of its outer border; and passes doAvn between it and the Iliacus, and beneath Poupart's ligament, into the thigh, Avhere it be- comes someAvhat flattened, and divides into an anterior or cutaneous, and a poste- rior or muscular part. Beneath Poupart's ligament, it is separated from the femoral artery by the Psoas muscle, and lies beneath the iliac fascia. Within the pelvis, the anterior crural nerve gives off some small branches to the Iliacus, and a branch to the femoral artery, Avhich is distributed upon the upper part of that vessel. The origin of this branch varies ; it occasionally arises higher than usual, or it may arise lower down in the thigh. External to the pelvis, the folloAving branches are given off:— From the Anterior Division. From the Posterior Division. Middle cutaneous. Muscular. Internal cutaneous. Articular. Long Saphenous. _ The Middle Cutaneous Nerve pierces the fascia lata (occasionally the Sarto- rius also), about three inches below Poupart's ligament, and divides into two branches, which descend in immediate proximity along the forepart of the thigh, ANTERIOR CRURAL. 523 distributing numerous branches to the integument as low as the front of the knee, where it joins a branch of the internal saphenous nerve. Its outer branch com- municates, above, Avith the crural branch of the genito-crural nerve ; and the inner branch with the internal cutaneous nerve below. The Sartorius muscle is sup- plied by this or the following nerve. The Internal Cutaneous Nerve passes obliquely across the upper part of the sheath of the femoral artery, and divides in front, or at the inner side, of that vessel, into tAvo branches, anterior and internal. The anterior branch perforates the fascia lata at the lower third of the thigh, and divides into two branches, one of which supplies the integument as Ioav down as the inner side of the knee ; the other crosses the patella at the outer side of the joint, communicating in its course with the long saphenous nerve. A cuta- neous filament is occasionally given off from this nerve, which accompanies the long saphenous vein ; and it sometimes communicates with the internal branch of the nerve. The internal branch descends along the posterior border of the Sartorius muscle to the knee, where it pierces the fascia lata, communicates with the long saphe- nous nerve, and gives off several cutaneous branches. The nerve then passes down the inner side of the leg, to the integument of wliich it is distributed. This nerve, beneath the fascia lata, joins in a plexiform network, by uniting Avith branches of the long saphenous and obturator nerves. When the communicating branch from the latter nerve is large, and continued to the integument of the leg, the inner branch of the internal cutaneous is small, and terminates at the plexus, occasionally giving off a feAV cutaneous filaments. This nerve, before subdividing, gives off a feAV filaments wliich pierce the fascia lata, to supply the integument of the inner side of the thigh, accompanying the long saphena vein; One of these filaments passes through the saphenous opening ; second becomes subcutaneous about the middle of the thigh ; and a third pierces the fascia at its loAver third. The Long or Internal Saphenous Nerve is the largest of the cutaneous branches of the anterior crural nerve. It approaches the femoral artery where this vessel passes beneath the Sartorius, and lies on its outer side, beneath the aponeurotic covering, as far as the opening in the lower part of the Adductor magnus. It then quits the artery, and descends vertically along the inner side of the knee, beneath the Sartorius, pierces the deep fascia betAveen the tendons of the Sartorius and Gracilis, and becomes subcutaneous. The nerve then passes along the inner side of the leg, accompanied by the internal saphenous vein, de- scends behind the internal border of the tibia, and, at the lower third of the leg, divides into two branches : one continues its course along the margin of the tibia, terminating at the inner ankle ; the other passes in front of the ankle, and is dis- tributed to the integument along the inner side of the foot, as far as the great toe. Branches. The long saphenous nerve, about the middle of the thigh, gives off a communicating branch, which joins the plexus formed by the obturator andjnternal cutaneous nerves. At the inner side of the knee, it gives off a large branch (nervus cut uncus pa- tella), which pierces the Sartorius and fascia lata, and is distributed to the integu- ment in front of the patella. This nerve communicates above the knee with the anterior branch of the internal cutaneous; below the. knee, Avith other branches of the long saphenous; and, on the outer side, of the joint, with branches of the mid- dle and external cutaneous nerves, forming a plexiform network, the plexus pa- telhe.. This nerve is occasionally small, and terminates by joining the internal cutaneous, Avhich supplies its place in front of the knee. _ Below the knee, the branches of the long saphenous nerve are distributed to the integument of the front and inner side of the leg, communicating with the cutaneous branches from the internal cutaneous or obturator nerve. The Deep Group of branches of the anterior crural nerve are muscular and articular. 524 SPINAL NERVES. The Muscular branches supply the Pectineus, and all the muscles on the front of the thigh, except the Tensor vaginae femoris, Avhich is supplied from the gluteal nerve, and the Sartorius, which is supplied by filaments from the middle or internal cutaneous nerves. The branches to the Pectineus, usually two in number, pass inwards behind the femoral vessels, and enter the muscle on its anterior surface. The branch to the Rectus muscle enters its under surface high up. The branch to the Vastus externus, of large size, folloAvs the course of the de- scending branch of the external circumflex artery, to the loAver part of the muscle. It gives off an articular, filament. The branches to the Vastus internus and Cruraeus enter the middle of those muscles. The Articular brandies, tAvo in number, supply the knee joint. One, a long slender filament, is derived from the nerve to the Vastus externus. It penetrates the capsular ligament of the joint on its anterior aspect. The other is derived from the nerve to the Vastus internus. It descends along the internal inter- muscular septum, accompanying the deep branch of the anastomotica magna, pierces the capsular ligament of the joint on its inner side, and supplies the synovial membrane. The Sacral and Coccygeal Nerves. The Sacral Nerves are five in number on each side. The four upper ones pass from the sacral canal through the sacral foramina ; the fifth escaping with the coccygeal nerve, from the sacral canal at its termination. The roots of origin of the upper sacral (and lumbar) nerves are the largest of all the spinal nerves ; whilst those of the lowest sacral and coccygeal are the smallest. The length of the roots of these nerves is very considerable, being longer than those of any of the other spinal nerves, on account of the spinal cord not extend- ing beyond the first lumbar vertebra. From their great length, and the appear- ance they present in connection Avith the spinal cord, the roots of origin of these nerves are called collectively the cauda equina. Each sacral and coccygeal nerve divides into two branches, anterior and posterior. The Posterior Sacral Nerves are small, diminish in size from above downAvards, and emerge, except the last, from the sacrum by the posterior sacral foramina. The three upper ones are covered, at their exit from the sacrum, by the Multi- fidus spinae, and divide into external and internal branches. The internal branches are small, and supply the Multifidus spinas. The external branches communicate Avith one another, and with the last lumbar and fourth sacral nerves, by means of anastomosing loops. These branches pass outAvards, to the outer surface of the great sacro-sciatic ligament, Avhere they form a second series of loops beneath the Glutaeus maximus. Cutaneous branches from these second series of loops, usually three in number, pierce this muscle; one near the posterior inferior spine of the ilium, another opposite the end of the sacrum ; and the third midAvay between these two. They supply the integument over the posterior part of the gluteal region. The two loiver posterior Sacral Nerves are situated below the Multifidus spinae. They are of small size, and join with each other, and Avith the coccygeal nerve, so as to form loops on the back of the sacrum, filaments from which supply the in- tegument over the coccyx. The Anterior Sacral Nerves diminish in size from above downAvards. The four upper ones emerge from the anterior sacral foramina; the anterior branch of the fifth, together with the coccygeal nerve, between the sacrum and the coccyx. All the anterior sacral nerves communicate with the sacral ganglia of the sympa- thetic, at their exit from the sacral foramina. The first nerve, of large size, unites with the lumbo-sacral nerve. The second equals in size the preceding, with which SACRAL PLEXUS. 525 it joins. The third, about one-fourth the size of the second, unites with the pre- ceding nerves, to form the sacral plexus. The fourth anterior Sacral Nerve sends a branch to join the sacral plexus. The remaining portion of the nerve divides into visceral and muscular branches: and a communicating filament descends to join the fifth sacral nerve. The visceral branches are distributed to the viscera of the pelvis, communicating with the sympathetic nerve. These branches ascend upon the rectum and bladder: in the female, upon the vagina and bladder, communicating with branches of the sympathetic to form the hypogastric plexus. The muscular brandies are distributed to the Levator ani, Coccygeus, and Sphincter ani. Cutaneous filaments arise from the latter branch, which supply the integument betAveen the anus and coccyx. The fifth anterior Sacryl Nerve, after passing from the loAver end of the sacral canal, pierces the Coccygeus muscle, and descends upon its anterior surface to the tip of the coccyx, where it perforates that muscle, to be distributed to the integu- ment over the back part and side of the coccyx. This nerve communicates above with the fourth, and below with the coccygeal nerve, and supplies the Coccygeus muscle. The anterior^ branch of the Coccygeal Nerve is a delicate filament which escapes at the termination of the sacral canal. It pierces the sacro-sciatic ligament and Coccygeus muscle, is joined by a branch from the fifth anterior sacral, and becomes lost in the integument at the back part and side of the coccyx. The posterior branch of the Coccygeal Nerve is small. It separates from the anterior in the sacral canal, and receives, as already mentioned, a communicating branch from the last sacral. It is lost in the fibrous structure on the back of the coccyx. Sacral Plexus. The sacral plexus is formed by the lumbo-sacral, the anterior branches of the three upper, and part of the fourth sacral nerves. These nerves proceed in differ- ent directions; the upper ones obliquely outwards, the lower ones nearly horizon- tally, and unite into a single, broad, flat cord. The sacral plexus is triangular in form, its base corresponding with the exit of the nerves from the sacrum, its apex with the loAver part of the great sacro-sciatic foramen. It rests upon the anterior surface of the Pyriformis, and is coA^ered in front by the pelvic fascia, Avhich sepa- rates it from the sciatic and pudic branches of the internal iliac artery, and from the viscera of the pelvis. The branches of the sacral plexus are:— Muscular. Pudic. Superior gluteal. Small sciatic. Great sciatic. The Muscular branches supply the Pyriformis, Obturator Internus, the two Ge- melli, and the Quadratus femoris. The branch to the Pyriformis arises either from the plexus, or from the upper sacral nerves: the branch to the Obturator internus arises at the junction of the lumbo-sacral and first sacral nerves; it crosses behind the spine of the ischium, and passes through the lesser sacro-sciatic foramen to the inner surface of the Obturator internus: the branch to the Gemellus superior arises from the loAver part of the plexus, near the pudic nerve: the small branch to the Gemellus inferior and Quadratus femoris also arises from the lower part of the plexus; it passes beneath the Gemelli and tendon of the Obturator internus, and supplies an articular branch to the hip joint. This branch is occasionally deriAred from the upper part of the great sciatic nerve. The Superior Gluteal Nerve arises from the back part of the lumbo-sacral; it passes from the pelvis through the great sacro-sciatic foramen above the Pyri- formis muscle, accompanied by the gluteal artery, and divides into a superior and an inferior branch. The superior branch follows the line of origin of the Glutaeus minimus, and sup- plies it and the Glutaeus medius. 526 SPINAL NERVES. The inferior branch crosses obliquely between the Glutaeus minimus and medius distributing filaments to both these muscles, and terminates in the Tensor vaginae femoris, extending nearly to its loAver end. The Pudic Nerve arises from the loAver part of the sacral plexus, and leaves the pelvis, through the great sacro-sciatic foramen, beloAv the Pyriformis. It then crosses the spine of the ischium, and re-enters the pelvis through the lesser sacro- sciatic foramen. It accompanies the pudic artery upAvards and forAvards along the outer Avail of the ischio-rectal fossa, being covered by the obturator fascia and divides into tAvo terminal branches, the perineal nerve, and the dorsal nerve of the penis. Near its origin, it gives off the inferior hemorrhoidal nerve. The Inferior Hemorrhoidal Nerve is occasionally derived from the sacral plexus. It passes across the iscliio-rectal fossa, Avith its accompanying vessels towards the loAver end of the rectum, and is distributed to the External sphincter and the integument around the anus. Branches of this nerve communicate with the inferior pudendal and superficial perineal nerves on the inner margin of the thigh. The Perineal Nerve, the most inferior and largest of the two terminal branches of the pudic, is situated beloAv the pudic artery. It accompanies the superficial perineal artery in the perinaeum, dividing into cutaneous and muscular branches. The cutaneous branches (superficial perineal) are tAvo in number, posterior and anterior. The posterior branch passes to the back part of the iscliio-rectal fossa distributing filaments to the Sphincter ani and integument in front of the anus which communicate with the inferior hemorrhoidal nerve: it then passes forwards with the anterior branch, to the back of the scrotum, communicating with this nerve and the inferior pudendal. The anterior branch passes to the forepart of the ischio-rectal fossa, in front of the preceding, and accompanies it to the scrotum and under part of the penis. This branch gives one or two filaments to the Levator ani. The muscular branches are distributed to the Transversus perinaei, Accelerator urinae, Erector penis, and Compressor urethrae. The nerve of the bulb supplies the corpus spongiosum ; some of its filaments run for some distance on the surface, before penetrating its interior. The Dorsal Nerve of the Penis is the superior division of the pudic nerve; it accompanies the pudic artery along the ramus of the ischium, and betAveen the two layers of the deep perineal fascia; it then pierces the suspensory ligament of the penis, and accompanies the arteria dorsalis penis to the glans, to which it is distributed. _ On the penis, this nerve gives off a cutaneous branch, which runs along the side of the organ; it is joined with branches of the sympathetic, and supplies the integument of the upper surface and sides of the penis and prepuce, giving a large branch to the corpus cavernosum. In the female, the pudic nerve is distributed to the parts analogous to those of the male; its superior division terminating in the clitoris, the inferior in the external labia and perinaeum. The Small Sciatic Nerve supplies the integument of the perinaeum and back part of the thigh and leg, and one muscle, the Glutaeus maximus. It is usually formed by the union of two branches, which arise from the lower part of the sacral plexus. It arises below the Pyriformis muscle, descends beneath the Glutaeus maximus with the sciatic artery, and at the lower border of that muscle passes along the back part of the thigh, beneath the fascia lata, to the lower part of the popliteal region, where it pierces the fascia and becomes cutaneous. It then accom- panies the external saphenous vein below the middle of the leg, its terminal fila- ments communicating with the external saphenous nerve. The branches of the small sciatic nerve are muscular (inferior gluteal) and cutaneous. The inferior gluteal consists of several large branches given off to the under surface of the Glutaeus maximus, near its lower part. The cutaneous brandies consist of two groups: internal and ascending. SCIATIC. 527 Fig. 270.—Cutaneous Nerves of Lower Extremity. Posterior View. Fig. 271.—Nerves of the Lower Extremity. Posterior View. X.tt OBTURATOR Small Sciatic Co tun. n » ictt n 9 ropi,t, i Finnic ■?ufex*0i~t 528 SPINAL NERVES. The internal cutaneous branches are distributed to the skin at the upper and inner side of the thigh, on its posterior aspect. One branch, longer than the rest the inferior pudendal, curves forward beloAV the tuber ischii, pierces the fascia lata on the outer side of the ramus of that bone, and is distributed to the integu- ment of the scrotum, communicating with the superficial perineal nerve. The ascending cutaneous branches consist of tAvo or three filaments, Avhich turn upwards round the loAver border of the Glutaeus maximus, to supply the integument covering its surface. One or two filaments occasionally descend along the outer side of the thigh, supplying the integument as far as the middle of this region. Tavo or three branches are given off from the lesser sciatic nerve as it descends beneath the fascia of the thigh; they supply the integument of the back part of the thigh, popliteal region, and upper part of the leg. The GreAt Sciatic Nerve supplies nearly the whole of the integument of the leg, the muscles of the back of the thigh, and of the leg and foot. It is the largest nervous cord in the body, measuring three-quarters of an inch in breadth and is the continuation of the lower part of the sacral plexus. It passes out of the pelvis through the great sacro-sciatic foramen, below the Pyriformis muscle. It descends betAveen the trochanter major and tuberosity of the ischium, along the back part of the thigh, to about its lower third, where it divides into two large branches, the internal and external popliteal nerves. This division may take place at any point between the sacral plexus and the lower third of the thigh. When the division occurs at the plexus, the two nerves descend together, side by side; or they may be separated, at their commencement, by the interposition of part or the whole of the Pyriformis muscle. As the nerve descends along the back of the thigh, it rests at first upon the External rotator muscles, together Avith the small sciatic nerve and artery, being covered by the Glutaeus maximus; lower down, it lies upon the Adductor magnus, being covered by the long head of the Biceps. The branches of the nerve, before its division, are articular and muscular. _ The articular branches arise from the upper part of the nerve; they supply the hip joint, perforating its fibrous capsule posteriorly. These branches are some- times derived from the sacral plexus. The muscular branches are distributed to the Flexors of the leg, viz., the Biceps, Semitendinosus and Semimembranosus, and a branch to the Adductor magnus. These branches are given off beneath the Biceps muscle. The Internal Popliteal Nerve, the larger of the tAvo terminal branches of the great sciatic nerve, descends along the back part of the thigh through the middle of the popliteal space, to the lower part of the Popliteus muscle, where it passes with the artery beneath the arch of the Soleus, and becomes the posterior tibial. It lies at first very superficial, and at the outer side of the popliteal artery; opposite the knee joint it is in close relation with these vessels, and crosses the artery to its inner side. The branches of this nerve are articular, muscular, and a cutaneous branch, the external or short saphenous nerve. . The Articular Branches, usually three in number, supply the knee joint; two of these branches accompany the superior and inferior internal articular arteries, and a third the azygos. The Muscular Branches, four or five in number, arise from the nerve as it lies between the two heads of the Gastrocnemius muscle; they supply this muscle, the Plantaris, Soleus, and Popliteus. The External or Short Saphenous Nerve descends between the two heads of the Gastrocnemius muscle, and about the middle of the back of the leg pierces the deep fascia, and receives a communicating branch (communicans peronei) from the external popliteal nerve. The nerve then continues its course down the leg near the outer margin of the tendo Achillis, in company with the external saphe- nous vein, winds round the outer malleolus, and is distributed to the integument PLANTAR. 529 Fig. 27*2—The Plantar Nerves. along the outer side of the foot, and little toe, communicating on the dorsum of the foot Avith the musculo-cutaneous nerve. The Posterior Tibial Nerve, the terminal branch of the Internal Popliteal Nerve, commences at the loAver border of the Popliteus muscle, and passes along the back part of the leg with the posterior tibial vessels to the interval betAveen the inner malleolus and the heel, Avhere it divides into the external and internal plantar nerves. It lies upon the deep muscles of the leg, and is covered by the deep fascia, the superficial muscles, and integument. In the upper part of its course, it lies to the inner side of the posterior tibial artery; but it soon crosses that vessel, and lies to its outer side as far as the ankle. In the lower third of the leg, it is placed parallel with the inner margin of the tendo Achillis. The branches of the posterior tibial nerve are muscular and plantar cutaneous. The muscular branches arise either separately, or by a common trunk from the upper part of the nerve. They supply the Tibialis posticus, Flexor longus digi- torum, and Flexor longus pollicis muscles; the branch to the latter muscle accom- panies the peroneal artery. The plantar cutaneous branch perforates the internal annular ligament, and sup- plies the integument of the heel and inner side of the sole of the foot. The Internal Plantar Nerve (Fig. 272), the larger of the tAvo terminal branches of the posterior tibial, accompanies the internal plantar artery along the inner side of the foot. From its origin at the inner ankle it passes forwards betAveen the Abductor pol- licis and Flexor brevis digitorum, divides opposite the bases of the metatarsal bones, into four digital branches, and communicates with the external plantar nerve. Branches. In its course, the internal plan- tar nerve gives off cutaneous branches, Avhich pierce the plantar fascia, and supply the integument of the sole of the foot; muscular branches, Avhich supply the Abductor pol- licis and Flexor brevis digitorum ; articular branches to the articulations of the tarsus and metatarsus ; and four digital branches. These pierce the plantar fascia in the clefts betAveen the toes, and are distributed in the following manner. The first supplies the inner border of the great toe, and sends a filament to the Flexor brevis pollicis muscle; the second bifurcates to supply the adjacent sides of the great and second toes, sending a filament to the first Lumbrical muscle ; the third digital branch supplies the adja- cent sides of the second and third toes and the second Lumbrical muscle ; and the fourth the corresponding sides of the third and fourth toes. This nerve recehres a commu- nicating branch from the external plantar nerve. It will be observed that the distribution of these branches is precisely similar to that of the median. Each digital nerve gives off cutaneous and articular filaments; and opposite the last phalanx sends a dorsal branch, Avhich supplies the structure around the nail, the continuation of the nerve being distri- buted to the ball of the toe. The External Plantar Nerve, the smaller of the tAvo, completes the nervous 36 530 SPINAL NERVES. supply to the structures of the foot, being distributed to the little toe and one-half of the fourth, as Avell as to some of the deep muscles. It passes obliquely for- Avards Avith the external plantar artery to the outer side of the foot, lying betAveen the Flexor brevis digitorum and Flexor accessorius ; and in the interval between the former muscle and Abductor minimi digiti, divides into a superficial and deep branch. Before its division, it supplies the Flexor accessorius and Abductor minimi digiti. The superficial branch separates into tAvo digital nerves; one, the smaller of the two, supplies the outer side of the little toe, the Flexor brevis minimi digiti, and the tAvo interosseous muscles of the fourth metatarsal space ; the other, and larger digital branch, supplies the adjoining sides of the fourth and fifth toes, and communicates Avith the internal and plantar nerve. The deep or muscular branch accompanies the external plantar artery into the deep part of the sole of the foot, beneath the tendons of the Flexor muscles and Adductor pollicis, and supplies all the interossei (except those in the fourth metatarsal space), the tAvo outer Lumbricales, the Adductor pollicis, and the Transversus pedis. The External Popliteal or Peroneal Nerve, about one-half the size of the internal popliteal, descends obliquely along the outer side of the popliteal space, close to the margin of the Biceps muscle, to the fibula ; and, about an inch beloAV the head of this bone, pierces the origin of the Peroneus longus, and divides be- neath this muscle into the anterior tibial and musculo-cutaneous nerves. The branches of the peroneal nerve, previous to its division, are articular and cutaneous. The articular branches, tvvo in number, accompany the superior and inferior external articular arteries to the outer side of the knee. The upper one occasion- ally arises from the great sciatic nerve, before its bifurcation. A third (recurrent) articular nerve is given off at the point of division of the peroneal nerve ; it ascends Avith the tibial recurrent artery through the Tibialis anticus muscle to the front of the knee, Avhich it supplies. The cutaneous branches, two or three in number, supply the integument along the back part and outer side of the leg, as far as its middle or loAver part; one of these, larger than the rest, the communicans peronei, arises near the head of the fibula, crosses the external head of the Gastrocnemius to the middle of the leg, Avhere it joins with the external saphenous. This nerve occasionally exists as a separate branch, Avhich is continued doAvn as far as the heel. The Anterior Tibial Nerve commences at the bifurcation of the peroneal nerve, between the fibula and upper part of the Peroneus longus, passes obliquely for- Avards beneath the Extensor longus digitorum to the forepart of the interosseous membrane, and reaches the outer side of the anterior tibial artery above the middle of the leg; it then descends with the artery to the front of the ankle joint, Avhere it divides into an external and an internal branch. This nerve lies at first on the outer side of the anterior tibial, then in front of it, and again at its outer side of, the ankle joint. The brandies of the anterior tibial, in its course through the leg, are muscular; these supply the Tibialis anticus, the Extensor longus digitorum, and Extensor proprius pollicis muscles. The external or tarsal branch of the anterior tibial, passes outAvards across the tarsus, beneath the Extensor brevis digitorum, and having become ganglionic, like the posterior interosseous nerve at the wrist, supplies the Extensor brevis digi- torum and the articulations of the tarsus and metatarsus. The internal branch, the continuation of the nerve, accompanies the dorsalis pedis artery along the inner side of the dorsum of the foot, and, at the first inter- osseous space, divides into two branches Avhich supply the adjacent sides of the great and second toes, communicating with the internal division of the musculo- cutaneous nerve. The Musculo-cutaneous branch supplies the muscles on the fibular side of the CUTANEOUS NERVES OF FOOT. 531 leg, and the integument of the dorsum of the foot. It passes forAvards betAveen the Peronei muscles and the Extensor longus digitorum, pierces the deep fascia at the loAver third of the leg, on its front and outer side, and divides into two branches. This nerve, in its course betAveen the muscles, gives off muscular branches to the Peroneus longus and brevis, and cutaneous filaments to the integu- ment of the loAver part of the leg. The internal branch of the musculo-cutaneous nerve passes in front of the ankle joint, and along the dorsum of the foot, it supplies the inner side of the great toe, and the adjoining sides of the second and third toes. It also supplies the integu- ment of the inner ankle and inner side of the foot, communicating Avith the internal saphenous nerve, and joins with the anterior tibial nerve, betAveen the great and second toes. The external branch, the larger, passes along the outer side of the dorsum of the foot, to be distributed to the adjoining sides of the third, fourth, and fifth toes. It also supplies the integument of the outer ankle and outer side of the foot, com- municating with the short saphenous nerve. The distribution of these nerves will be found to vary ; together, they supply all the toes excepting the outer side of the little toe, and the adjoining sides of the great and second toes. The Sympathetic Nerve. rPIIE Sympathetic Nerve consists of a series of ganglia connected together bv intervening cords, extending on each side of the vertebral column from the base of the skull to the coccyx. It may, moreover, be traced up into the head, where the ganglia occupy spaces betAveen the cranial and facial bones. These two gangliated cords lie parallel Avith one another as far as the sacrum, on Avhich bone they converge, communicating together in front of the coccyx, through a single ganglion (ganglion impar), placed in front of this bone. Some anatomists also state that the tAvo cords are joined at their cephalic extremity, through a small ganglion (the ganglion of Ribes), situated upon the anterior communicating artery. Moreover, the chains of opposite sides communicate together betAveen these tAvo extremities in several parts, by means of the nervous cords that arise from them. The ganglia are somewhat less numerous than the vertebrae : thus there are only three in the cervical region, twelve in the dorsal, four in the lumbar, five in the sacral, and one in the coccygeal. The sympathetic nerves, for convenience of description, may be divided into several parts, according to the position occupied by each ; and the number of ganglia of which each part is composed, may be thus arranged : Cephalic portion, Cervical "... Dorsal ' ki Lumbar "... Sacral •• Coccygeal " Each ganglion may be regarded as a distinct centre, from, or to, which branches pass in various directions. These branches may be thus arranged: 1. Branches of communication between the ganglia. 2. Branches of communication with the cerebral or spinal nerves. 3. Primary branches passing to be distributed to the arteries in the vicinity of the ganglia, and to the viscera, or proceeding to other ganglia placed in the thorax, abdomen, or pelvis. 1. The branches of communication between the ganglia are composed of gray and white nerve-fibres, the latter being continuous with those fibres of the spinal nerves wliich pass to the ganglia. 2. The branches of communication betAveen the ganglia and the cerebral or spinal nerves also consist of a white and a gray portion ; the former proceeding from the spinal nerve to the ganglion, the latter passing from the ganglion to the spinal nerve. 3. The primary branches of distribution also consist of two kinds of nerve- fibres, the sympathetic and spinal. They have a remarkable tendency to form intricate plexuses, which encircle the bloodvessels and are conducted by them to the viscera. The greater number, however, of these branches pass to a series of ganglia, or ganglionic masses, of variable size, situated in the large cavities of the trunk, the thorax, and abdomen; and are connected with the roots of the great arteries of the viscera. These ganglia are single and unsysmmetrical, and are called the cardiac and semilunar. From these visceral ganglia numerous plexuses are derived, which entwine round the bloodvessels, and are conducted bv them to the viscera. 1 3 ganglia a 12 a 1 " 5 a 1 a SYMPATHETIC NERVE. 533 Fig. 273.—The Sympathetic Nerve. Si'pr-riir C*pri< l-7i(7dlfi Cervical Grtj/c/7i'nn / Inferior Cervical Ganglion T'Tiarynqeal Branc/iea Cardinc li l . -Deep Cardiac Plexus Superficial Cardiac Plexus Solar P'I'exus Aortic Plexus Hypogastric fie a. us Smc,;,! C«„:,tia Cunrjlion. Intpar 531 SYMPATHETIC NERVE. Cephalic Portion of the Sympathetic. The Cephalic portion of the sympathetic consists of four ganglia. 1. The ophthalmic ganglion. 2. The spheno-palatine, or Meckel's ganglion. 3. The otic, or Arnold's ganglion. 4. The submaxillary ganglion. These have been already described in connection with each of the three divisions of the fifth nerve.1 Cervical Portion of the Sympathetic. The Cervical portion of the sympathetic consists of three ganglia on each side, Avhich are distinguished according to their position, as the superior, middle, and inferior cervical. The Superior Cervical Ganglion, the largest of the three, is placed opposite the second and third cervical vertebrae, and sometimes as Ioav as the fourth or fifth. It is of a reddish-gray color, and usually fusiform in shape: sometimes broad, and occasionally constricted at intervals, so as to give rise to the opinion, that it con- sists of the coalescence of several smaller ganglia. It is in relation in front with the sheath of the internal carotid artery, and internal jugular vein; and behind, it lies on the Rectus capitis anticus major muscle. Its branches may be divided into superior, inferior, external, internal, and anterior. The superior branch appears to be a direct continuation of the ganglion. It is soft in texture, and of a reddish color. It ascends by the side of the internal carotid artery, and entering the carotid canal in the temporal bone, divides into two branches, Avhich lie, one on the outer, and the other on the inner side, of that vessel. The outer branch, the larger of the two, distributes filaments to the internal carotid artery, and forms the carotid plexus. _ The inner branch also distributes filaments to the internal carotid, and, con- tinuing onwards, forms the cavernous plexus. The inferior or descending branch of the superior cervical ganglion commu- nicates with the middle cervical ganglion. The external branches are numerous, and communicate Avith the cranial nerves, and with the first four cervical nerves. The branches of communication with the cranial nerves consist of delicate filaments, which pass from the superior cervical ganglion to the ganglion of the trunk of the pneumogastric, and to the ninth nerve. A separate filament from the cervical ganglion subdivides and joins the petrosal ganglion of the glosso-pharyngeal, and the ganglion of the root of the pneumogastric in the jugular foramen. The internal branches are three in number: pharyngeal, laryngeal, and the superior cardiac nerve. The pharyngeal branches pass obliquely inwards to the side of the pharynx, where they communicate with branches from the pneumo- gastric, glosso-pharyngeal, and external laryngeal nerves, and assist in forming the pharyngeal plexus. The laryngeal branches unite with the superior laryngeal nerve and its branches. The superior cardiac nerve will be described in connection with the other cardiac nerves. The anterior branches ramify upon the external carotid artery and its branches, forming around each a delicate plexus, on the nerves composing wliich small ganglia are occasionally found. These ganglia have been named, according to their position, intercarotid (one placed at the angle of bifurcation of the common carotid), lingual, temporal, and pharyngeal. The plexuses accompanying some of these arteries have important communications with other nerves. That surround- ing the external carotid is connected Avith the digastric branch of the facial; that surrounding the facial communicates with the submaxillary ganglion by one or two filaments; and that accompanying the middle meningeal artery sends offsets, CERVICAL GANGLIA. 535 which pass to the otic ganglion and to the intumescentia gangliformis of the facial nerve. The Middle Cervical Ganglion (thyroid ganglion) is the smallest of the three cervical ganglia, and is occasionally altogether wanting. It is placed oppo- site the fifth cervical vertebra, usually upon the inferior thyroid artery ; hence the name " thyroid ganglion," assigned to it by Haller. Its superior branches ascend to communicate Ayith the superior cervical gan- glion. Its inferior branches descend to communicate with the inferior cervical gan- glion. Its external branches pass outwards to join the fifth and sixth cervical nerves. These branches are not constantly found. Its internal branches are the thyroid, and the middle cardiac nerve. The thyroid branches are small filaments, Avhich accompany the inferior thyroid artery to the thyroid gland ; they communicate, on the artery, with the superior cardiac nerve, and in the gland with branches, from the recurrent and external laryngeal nerve. The middle cardiac nerve is described Avith the other cardiac nerves. The Inferior Cervical Ganglion is situated between the base of the trans- verse process of the last cervical vertebra and the neck of the first rib, on the inner side of the superior intercostal artery. Its form is irregular ; it is larger in size than the preceding, and frequently joined Avith the first thoracic ganglion. Its sujicrior branches communicate with the middle cervical gano-lion. Its inferior branches descend, some in front, others behind °the subclavian artery, to join the first thoracic ganglion. The most important of these branches constitutes the inferior cardiac nerve, to be presently described. The external branches consist of several filaments, some of Avhich communicate with the seventh and eighth cervical nerves ; others accompany the vertebral artery along the vertebral canal, forming a plexus around this vessel, supplying it with filaments, and communicating Avith the cervical spinal nerves as high as the fourth. Carotid and Cavernous Plexuses. The carotid plexus is situated on the outer side of the internal carotid. Filaments from this plexus occasionally form a small gangliform SAvelling on the under surface of the artery, Avhich is called the carotid ganglion. The carotid plexus communicates Avith the Gasserian ganglion of the fifth, Avith the sixth nerve, and spheno-palatine ganglion, and distributes filaments to the Avail of the carotid artery, and to the dura mater (Valentin). The communicating branches Avith the sixth nerve consist of one or tAvo fila- ments, Avhich join that nerve as it lies upon the outer side of the internal carotid. Other filaments are also connected Avith the Gasserian ganglion of the fifth nerve. The communication Avith the spheno-palatine ganglion is effected by the carotid portion of the Vidian nerve, Avhich passes forAvards, through the cartilaginous substance filling in the foramen lacerum medium, along the pterygoid canal, to the spheno-palatine ganglion. In this canal it joins the petrosal branch of the Vidian. The cavernous plexus is situated beloAV, and to the inner side of that part of the internal carotid, Avhich is placed by the side of the sella Turcica, in the cavernous sinus, and is formed chiefly by the internal division of the ascending branch from the superior cervical ganglion. It communicates with the third, fourth, fifth, and sixth nerves, and Avith the ophthalmic ganglion, and distributes filaments to the wall of the internal carotid. The branch of communication with the third nerve joins it at its point of division ; the branch to the fourth nerve joins it as it lies on the outer Avail of the cavernous sinus ; other filaments are connected Avith the under surface of the trunk of the ophthalmic nerve ; and a second filament of communication joins the sixth nerve. The filament of connection with the ophthalmic ganglion arises from the ante- 536 SYMPATHETIC NERVE. rior part of the cavernous plexus ; it accompanies the nasal nerve, or continues forAvards as a separate branch. The terminal filaments from the carotid and cavernous plexuses are prolonged along the internal carotid, forming plexuses Avhich entAvine around the cerebral and ophthalmic arteries ; along the former vessel they may be traced on to the pia mater ; along the latter, into the orbit, where they accompany each of the subdivisions of the vessel, a separate plexus passing Avith the arteria centralis retinae into the interior of the eyeball. Cardiac Nerves. The cardiac nerves are three in number : superior, middle, and inferior, one being derived from each of the cervical ganglia. The Superior Cardiac Nerve (nervus superficialis cordis) arises by two or more branches from the superior cervical ganglion, and occasionally receives a filament from the cord of communication between the first and second cervical ganglia. It runs down the neck behind the common carotid artery, lying upon the Longus colli muscle ; and crosses in front of the inferior thyroid artery, and the recurrent laryngeal nerve. The right superior cardiac nerve, at the root of the neck, passes either in front or behind the subclavian artery, and along the arteria innominata, to the back part of the arch of the aorta, to the deep cardiac plexus. This nerve, in its course, is connected with other branches of the sympathetic; about the middle of the neck it receives filaments from the external laryngeal nerve; loAver down, one or tAvo twigs from the pneumogastric ; and as it enters the thorax, it joins with the recurrent laryngeal. Filaments from this nerve accompany the inferior thy- roid artery to the thyroid gland. The left superior cardiac nerve runs by the side of the left carotid artery, and in front of the arch of the aorta, to the superficial cardiac plexus ; it occa- sionally passes behind this vessel, and terminates in the deep cardiac plexus. The Middle Cardiac Nerve (nervus cardiacus magnus), the largest of the three, arises from the middle cervical ganglion, or from the interganglionic cord betAveen the middle and inferior ganglia. On the right side, it descends behind the common carotid artery ; and at the root of the neck passes either in front or behind the subclavian artery ; it then descends on the trachea, receives a few filaments from the recurrent laryngeal nerve, and joins the deep cardiac plexus. In the neck, it communicates with the superior cardiac and recurrent laryngeal nerves. On the left side, the middle cardiac nerve enters the chest between the left carotid and subclavian arteries, and joins the left side of the deep cardiac plexus. The Inferior Cardiac Nerve (nervus cardiacus minor) arises from the inferior cervical or first thoracic ganglion. It passes down behind the subclavian artery, and along the front of the trachea, to join the deep cardiac plexus. It communi- cates freely behind.the subclavian artery with the recurrent laryngeal and middle cardiac nerves. _ The Great or Deep Cardiac Plexus (Plexus Magnus Profundus—-Scarpa) is situated in front of the trachea at its bifurcation, above the point of division of the pulmonary artery, and behind the arch of the aorta. It is formed bv the cardiac nerves derived from the cervical ganglia of the sympathetic, and the cardiac branches of the recurrent laryngeal and pneumogastric. The only cardiac nerves which do not enter into the formation of this plexus are the left superior cardiac nerve and the left inferior cardiac branch from the pneumogastric. The branches derived from the great cardiac plexus form the posterior coronary plexus and part of the anterior coronary plexus, whilst a few filaments proceed to the pulmonary plexuses, and to the auricles of the heart. The branches from the right side of this plexus pass some in front and others behind the right pulmonary artery ; the former, the more numerous, transmit a few filaments to the anterior pulmonary plexus, and are continued along the trunk THORACIC GANGLIA. 537 of the pulmonary artery, to form part of the anterior coronary plexus; those be- hind the pulmonary artery distribute a feAV filaments to the right auricle, and form part of the posterior coronary plexus. The branches from the left side of the cardiac plexus distribute a few filaments to the left auricle of the heart and the anterior pulmonary plexus, and then pass on to form the greater part of the posterior coronary plexus, a feAV branches passing to the superficial cardiac plexus. The Superficial or Anterior Cardiac Plexus lies beneath the arch of the aorta, in front of the right pulmonary artery. It is formed by the left superior cardiac nerve, the left (and occasionally the right) inferior cardiac branches of the pneu- mogastric, and by filaments from the deep cardiac plexus. A small gano-lion (cardiac ganglion of Wrisberg) is occasionally found connected with these nerves at their point of junction. This ganglion, when present, is situated immediately beneath the arch of the aorta, on the right side of the ductus arteriosus. The superficial cardiac plexus forms the anterior part of the great coronary plexus, and several filaments pass, along the pulmonary artery to the left anterior pul- monary plexus. The Posterior Coronary Plexus is formed chiefly by filaments from the left side of the deep cardiac plexus, and by a few from the right side. It surrounds the branches of the coronary artery at the back of the heart, and its filaments are distributed Avith those vessels to the muscular substance of the ventricles. The Anterior Coronary Plexus is prolonged chiefly from the superficial cardiac plexus, but receives filaments from the deep cardiac plexus. Passing forwards betAveen the aorta and pulmonary artery, it accompanies the right coronary artery on the anterior surface of the heart. Valentin has described nervous filaments ramifying under the endocardium : hut they are less distinct in man than in the other mammalia; and Remak and hee have found, in several mammalia (the latter in man), numerous small ganglia on the branches of these nerves, both on the surface of the heart and in its mus- cular substance. Thoracic Part of the Sympathetic The thoracic portion of the sympathetic consists of a series of ganglia, which usually correspond in number to that of the vertebra? ; but, from the occasional coalescence of tAvo, their number is uncertain. These ganglia are placed on each side of the spine, resting against the heads of the ribs, and covered by the pleura costalis : the last tAvo are, hoAvever, anterior to the rest, being placed on the side of the bodies of the vertebrae. The ganglia are small in size, and of a grayish color. The first, larger than the rest, is of an elongated form, and usually blended with the last cervical. They are connected together by cord-like prolongations from their substance. The external branches from each ganglion, usually tAvo in number, communicate with each of the dorsal spinal nerves The internal branches from the six upper ganglia are very small, and distribute filaments to the thoracic aorta and its branches, besides small branches to the bodies of the vertebrae and their ligaments. Branches from the third and fourih ganglia form part of the posterior pul- monary plexus. The branches of the six lower ganglia are large and white in color ; they distribute filaments to the aorta, and unite to form the three splanchnic nerves. These are named, the great, the lesser, and the smallest or renal splanchnic. The Great Splanchnic Nerve is of a Avhite color, firm in texture, and bears a marked contrast to the ganglionic nerves. It is formed by branches from all the thoracic ganglia from the sixth to the tenth, receiving filaments (according to Mr. Beck) from all the thoracic ganglia above the sixth. These roots unite to form a round cord of considerable size. It descends obliquely inAvards in front of the bodies of the vertebrae along the posterior mediastinum, perforates the crus 538 SYMPATHETIC NERVE. of the Diaphragm, and terminates in the semilunar ganglion, distributing fila- ments to the renal plexus and suprarenal gland. The Lesser Splanchnic Nerve is formed by filaments from the tenth and eleventh ganglia, and from the cord betAveen them. It pierces the Diaphragm with the preceding nerve, and joins the cceliac plexus. It communicates in the chest with the great splanchnic nerve, and occasionally sends filaments to the renal plexus. The Smallest or Renal Splanchnic Nerve arises from the last ganglion, and piercing the Diaphragm, terminates in the renal plexus and lower part of the coeliac plexus. It occasionally communicates Avith the preceding nerve. A striking analogy appears to exist between the splanchnic and the cardiac nerves. The cardiac nerves are three in number ; they arise from the three cervical ganglia, and are distributed to a large and important organ in the thoracic cavity. The splanchnic nerves, also three in number, are connected Avith all the dorsal ganglia, and are distributed to important organs in the abdominal cavity. The Epigastric or Solar Plexus supplies all the viscera in the abdominal cavity. It consists of a dense network of nerves and ganglia, situated behind the stomach and in front of the aorta and crura of the Diaphragm. It surrounds the coeliac axis and root of the superior mesenteric artery, extending doAvnwards as Ioav as the pancreas, and outAvards to the suprarenal capsules. This plexus, and the ganglia connected with it, receive the great splanchnic nerve of both sides, part of the lesser splanchnic nerves, and the termination of the right pneumo- gastric. It distributes filaments, which accompany, under the.nameCof plexuses, all the branches from the front of the abdominal aorta. The semilunar ganglia, two in number, one on each side, are the largest o-an- gha in the body. They are large irregular gangliform masses, formed by°the aggregation of smaller ganglia, having interspaces between them. They are situated by the side of the coeliac axis and superior mesenteric artery, close to the suprarenal glands; the one on the right side lies beneath the vena cava; the upper part of each ganglion is joined by the greater and lesser splanchnic nerves, and to the inner side of each the branches of the solar plexus are con- nected. From the solar plexus are derived the following:— Phrenic or Diaphragmatic plexus. Renal plexus. Gastric plexus. Superior mesenteric plexus. Hepatic plexus. Spermatic plexus. Splenic plexus. Inferior mesenteric plexus. Suprarenal plexus. _ The Phrenic Plexus accompanies the phrenic artery to the Diaphragm, which it supplies, some filaments passing to the suprarenal gland. It arises from the upper part of the semilunar ganglion, and is larger on the right than on the .left side. In connection with this plexus, on the right side, at its point of junction with the phrenic nerve, is a small ganglion (ganglion diaphragmaticum). This ganglion is placed on the under surface of the Diaphragm, near the suprarenal gland. Its branches are distributed to the vena cava, suprarenal gland, and the hepatic plexus. The ganglion is absent on the left side. The Suprarenal Plexus is formed by branches from the solar plexus, from the semilunar ganglion, and from the splanchnic and phrenic nerves, a ganglion being formed at the point of junction of the latter nerve. It supplies the suprarenal gland. The branches of this plexus are remarkable for their large size, m comparison with the size of the organ they supply. The Renal Plexus is formed by filamenTs from the solar plexus, the outer part of the semilunar ganglion, and the aortic plexus. It is also joined bv filaments from the lesser and smallest splanchnic nerves. The nerves from these sources, fifteen or twenty in number, have numerous ganglia developed upon them. They accompany the branches of the renal artery into the kidney; some filaments on SOLAR PLEXUS; SEMILUNAR GANGLIA. 539 the right side being distributed to the vena cava, and others to the spermatic plexus on both sides. The Spermatic Plexus is derived from the renal plexus, receiving branches from the aortic plexus. It accompanies the spermatic vessels to the testes. In the female, the ovarian plexus is distributed to the ovaries and fundus of the uterus. The Cceliac Plexus, of large size, is a direct continuation from the solar plexus: it surrounds the coeliac artery, and subdivides into the gastric, hepatic, and splenic plexuses. It receives branches from one or more of the splanchnic nerves, and, on the left side, a filament from the pneumogastric. The Gastric Plexus accompanies the gastric artery along the lesser curvature of the stomach, and joins with branches from the left pneumogastric nerve. It is distributed to the stomach. The Hepatic Plexus, the largest offset from the cceliac plexus, receives filaments from the left pneumogastric and right phrenic nerves. It accompanies the hepatic artery, ramifying in the substance of the liver, upon its branches, and upon those of the vena portae. Branches from this plexus accompany all the divisions of the hepatic artery. Thus there is a pyloric plexus accompanying the pyloric branch of the hepatic, which joins with the gastric plexus, and pneumogastric nerves. There is also a gastro-duodenal plexus, which subdivides into the pancreatico-duodenai plexus, which accompanies the pancreatico-duodenai artery, to supply the pancreas and duodenum, joining with branches from the mesenteric plexus; and a gastro-epiploic plexus, Avhich accompanies the right gastro-epiploic artery along the great curva- ture of the stomach, and anastomoses with branches from the splenic plexus. A cystic plexus, wliich supplies the gall-bladder, also arises from the hepatic plexus, near the liver. The Splenic Plexus is formed by branches from the right and left semilunar ganglia, and from the right pneumogastric nerve. It accompanies the splenic artery and its branches to the substance of the spleen, giving off, in its course, filaments to the pancreas (pancreatic plexus), and the left gastro-epiploic plexus', which accompanies the gastro-epiploica sinistra artery along the convex border of the stomach. The Superior Mesenteric Plexus is a continuation of the loAver part of the great solar plexus, receiving a branch from the junction of the right pneumogastric nerve Avith the coeliac plexus. It surrounds the superior mesenteric artery, Avhich it accompanies into the mesentery, and divides into a number of secondary plexuses, which are distributed to all the parts supplied by the artery, viz., pancreatic branches to the pancreas ; intestinal branches, Avhich supply the Avhole of the small intestine; and ileo-colic, right colic, and middle colic branches, Avhich supply the corresponding parts of the great intestine. The nerves composing this plexus are white in color, and firm in texture, and have numerous ganglia developed upon them near their origin. The Aortic Plexus is formed by branches on each side, from the semilunar gan- glia and renal plexuses, receiving filaments from some of the lumbar ganglia. It is situated upon the sides and front of the aorta, between the origins of the supe- rior and inferior mesenteric arteries. From this plexus arise the inferior mesen- teric, part of the spermatic, and the hypogastric plexuses ; and it distributes fila- ments to the inferior cava. The Inferior Mesenteric Plexus is derived chiefly from the left side of the aortic plexus. It surrounds the inferior mesenteric artery, and divides into a number of secondary plexuses, Avhich are distributed to all the parts supplied by the artery, viz., the left colic and sigmoid plexuses, to the descending and sigmoid flexure of the colon ; and the superior hemorrhoidal plexus, wliich supplies the upper part of the rectum, and joins in the pelvis with branches of the left hypo- gastric plexus. 510 SYMPATHETIC NERVE. The Lumbar Portion or the Sympathetic. The lumbar portion of the sympathetic is situated in front of the vertebral column, along the inner margin of the Psoas muscle. It consists usually of four ganglia, connected together by interganghonic cords. The ganglia are of small size, of a grayish color, hordeiform in shape, and placed much nearer the median line than the thoracic ganglia. The superior and inferior branches of the lumbar ganglia serve to communicate betAveen the chain of ganglia in this region. They are usually single, and of a white color. The external brandies communicate Avith the lumbar spinal nerves. From the situation of the lumbar ganglia, these branches are longer than in the other regions. They are usually two in number for each ganglion, and accompany the lumbar arteries around the sides of the bodies of the vertebrae, passing beneath the fibrous arches from which the fibres of the Psoas muscle partly arise. The internal branches pass inAvards, in front of the aorta, and form the lumbar aortic plexus (already described). Other branches descend in front of the common iliac arteries, and join, over the promontory of the sacrum, to form the hvpo