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It first saw the light in the spring of 1840, and’ now, in the autumn of 1844, has reached its Third Edition. © In this short period, less than five years, five thousand copies have been distributed among the Members of the Profession, many also taking their place in the libraries of Gentlemen, ‘who, although not of the Profession, justly consider that some ge- neral knowledge of the structure of the body is an essential part of a liberal education.. In the same’ period, a second edition of the work has appeared in America; and a transla- tion, from the pen of Dr. Hollstein, has been completed in Berlin. , ‘Thus the volume has quickly returned for review to the hands of the Author ; and he trusts that an examination of the second and present editions will prove that he has not neg- lected this advantage. He has carefully corrected such over- sights and omissions as may have occurred in the completion of a work on so extensive a subject ; many parts which seemed seantily treated, he has entirely re-written ; and he has endea- voured to give as full a description of every point in Anatomy, whether important or trivial, as is consistent with the limits and objects of a Practical Manual. Two features in the Anatomist’s Vade Mecum appear to the Author to deserve notice :—the first relates to the labours of his professional brethren ; the second to the illustrations con- tained in the work. On the first of these heads the Author begs to remark, that he considers it a duty, as well to them as to his readers and himself, to quote all recent observations and Vili PREFACE. discoveries in Anatomy which may have interest, and to give as complete an abstract of such discoveries as the scheme of the work will permit. By pursuing this plan, the Author trusts to distinguish his volume as the Record of the Profes- sion at large, and not as the text-book merely of a particular school. And, in furtherance of his object, he has to request a continuance of those communications from scientific investiga- tors, which have hitherto so materially aided him. The woodcut Illustrations which accompany the Anatomist’s Vade Mecum have been increased with each edition. The number which appeared with the first was one hundred and fifty ; with the second, one hundred and sixty-seven ; and in the present they fall little short of two hundred. Severel of the new figures are illustrative of General Anatomy, and, to insure their absolute correctness, have been drawn from the microscope by the Author himself, with the aid of the camera lucida. Figures 2, 3, and 4, showing the changes which occur during the development of bone ; figures 47, 48, and 49, the minute anatomy of cartilage ; and figure 80, the struc-. ture of the ultimate muscular fibril, are examples of such drawings. The structure exhibited in the latter figure formed the subject of a paper which was read before the Royal So- ciety during the present year. Upper Charlotte Street, Fitzroy Square, November, 1844. CONTENTS. —_—_————- CHAPTER I. OSTEOLOGY. Page : Page Definition — Chemical on Base of the skull 56 of bone s 1 Face . : * 5 60 Division into classes. ‘ . 2 | Orbits . 61 Structure of bone . > 4 . 2 | Nasal fosse 61 Development of bone. poiccmarest Peet... 63 The skeleton . F . es eD Structure . os es . 64 Vertebral column . 10 Development . . ° . 66 Cervical vertebree 1l Growth ‘ ‘ : 2 68 Dorsal vertebre . 4 s 13 Eruption P x : . 69 Lumbar vertebrz 14 Succession . F , 7 - 70 General considerations 15 Oshyoides . 70 Development . 17 | Thorax and upper extremity . 71 Attachment of muscles 18 Sternum - cr Sacrum ‘ 18 Ribs—Costal cartilages 73 Coccyx “ . 20 Clavicle . . 75 Bones of the cranium . F 21 Scapula ‘ . 3 76 Occipital bone ‘ a 21 Humerus . 78 Parietal bone . . 24 Ulna . ‘ 80 Frontal bone’. . : 26 Radius . 81 Temporal bone . + ° 29 Carpal bones : 2 bp 8B Sphenoid bone . ; 35 Metacarpal bones. ‘ o*. 87 Ethmoid bone . ‘ " 39 osageay 47 ‘ 88 Bones of the face . : . « 41 | Pelvis an lower extremity 2 88 ° 4] Os innominatum ° P 89 Superior maxillary F » 41 Tlium—Ischium . 8 ; - 90 bone. ‘ 45 Os pubis. gl Malar bone . : 45 Pelvis —Its Divisions —Axes— Palate bone 46 eters ./ 98 Inferior turbineiba bone 48 Femur “5 Vomer . . . » 49 Patella—Tibia wv . 98 Inferior maxillary . 50 Fibula a * r . . 99 Table of developments, articula- Tarsal bones . Peart | . 101 tions, &e. » 52 Metatarsal bones ‘ ; - 105 Sutures 52 Phalanges . : : F . 107 Regions of the skull 54 | Sesamoidbones . - a. 307 CHAPTER II. THE LIGAMENTS. Page Page Forms of articulation . . 109 General anatomy of gam Synarthrosis—Amphi-arthrosis. 109 structures . ‘ = 412 ‘. Diarthrosis ; . , 1 1 0 Cc nd . . . . 1 12 Movements of joints . Aa Fibrous-cartilage . 114 Gliding—Angular movement 111 Ligament > ‘ ‘ » 215 Circumduction—Rotation . a Synovial membrane . : 117 LIGAMENTS OF THE TRUNK— ARRANGEMENT. ; Articulation of the vertebral column . Of the atlas with the occipital bone Of the axis with the occipital me . Of the atlas with the axis. th Of the lower jaw. . Of the ribs with the vertebrae 5 Of the ribs with the sternum, and with each other . Of the vertebral — _ the pelvis . . Of the pelvis . LIGAMENTS OF THE UPPER EX- TREMITY . Sterno-clavicular articulation Scapulo-clavicular articulation CONTENTS. Page 117 118 121 123 124 125 128 © 129 139 131 134 135 136 Ligaments of the scapula... Shoulder-joint . . ° : Elbow-joint . : ° Radio-ulnar articulation Wrist-joint . Articulations of the carpal bones . Carpo-metacarpal articulation Metacarpo-phalangeal articulation Articolation, of the phalanges LIGAMENTS OF THE LOWER EX- TREMITY . * cs Hip-joint . ° . Knee-joint Articulation between the tibia and fibula . Ankle-joint . Articulation of the tarsal bones : Tarso-metatarsal articulation : ] 1 articulation Articubanin of the phalanges CHAPTER III. THE MUSCLES. General anatomy of muscle . 3 Nomenclature—Structure MUuscLES OF THE HEAD AND FACE Bae y : Epicranial region . Orbital group Ocular group Nasal gro ‘ . nes rior er labial group . . erior labial group : Maxillary group . 4 . . Auricular group . : MUSCLES OF TE NECK : Superficial gr Depressors of ae os hyoides and larynx ° Elevators of the os hyoides 3 Muscles of the tongue . Muscles of the pharynx Muscles of the soft palate Preevertebal muscles ; MUSCLES OF THE TRUNK. Muscles of the back Page 159 60 Page 137 138 139 140 141 142 143 145 145 146 146 147 152 153 154 156 157 158 Page Table of origins and insertions of the muscles of the back . Muscles of the thorax . : ; Muscles of the abdomen Muscles of the perineum U Muscles of the female perineum . MUSCLES OF THE UPPER EX- TREMITY . . J Anterior thoracic region Lateral thoracic region Anterior scapular region Posterior scapular region Acromial region . : § Anterior humeral region. - Posterior humeral region Anterior brachial region “ ‘ Posterior brachial oe ; . Muscles of the hand ° : MUSCLES OF THE LOWER EX- TREMITY . ‘ . Gluteal region . ‘ : 5 Anterior femoral region i = Internal femoral region Posterior femoral region Anterior tibial region . Posterior tibial region . Fibular region. . Foot—Dorsal region. Plantar region . 208 210 211 221 225 CONTENTS. CHAPTER IV. General anatomy . . > -FASCI&Z OF THE HEAD AND NECK Temporal fascia Cervical fascia . J FASCIA OF THE TRUNK Thoracic fascia . 3 3 Fascia transversalis . Oblique inguinal hernia Congenital hernia E A Encysted hernia . . : . Direct inguinal hernia . Fasciailiaca. . . pte As THE FASCIZ. Page 276 } Fascia pelvica : : . 277 Obturator fascia . : 277 | Superficial perineal fascia 277 | Deep perineal fascia . . : 279 | FASCI& OF THE UPPER EXTRE- 279 MITY. ; , 279 | FASCIZ OF THE LOWER EXTRE- 280 MITY. ° . ° : 281 | Fascia lata - 281 Femoral hernia . ns 281 | Plantar fascia ‘ i : 282 CHAPTER V. THE ARTERIES. General anatomy of arteries ~ ng Seg ak Aorta . : 4 Table of branches F . Coronary arteries ‘ Arteria innominata Common carotid arteries External carotid artery Table of branches : Superior thyroid artery . : Lingual artery : ‘ . Facial artery: . 3 , : Mastoid artery . - Occipital artery Posterior auricular artery Parotidean arteries . Ascending pharyngeal artery Transverse facial artery é Temporal artery : F . Internal maxillary artery . : Internal carotid artery . “ Ophthalmic artery . : Anterior cerebral artery Middle cerebral artery Subclavian artery : ; Table of branches . ‘ Vertebral artery . 3 Basilar artery ‘ é 3 Circle of Willis : . ° Inferior thyroid artery . Supra-scapular artery — Poste- rior scapular. Page 292 293 296 298 298 299 300 301 301 302 303 304 305 305 305 306 306 306 307 307 309 311 313 313 313 316 316 316 317 319 319 Subclavian artery—continued. Superficialis cervicis — Profun- da.cervicis . . Superior intercostal artery—In- ternal mammary < ‘ Axillary artery’ . . . . Table of branches . . : Brachial artery . . : : Radial artery ‘ . . . Ulnar artery . : Thoracic aorta; branches. Abdominal aorta ; branches Phrenic arteries : Ceeliac axis—Gastric artery Hepatic artery ° . Splenic artery . : Superior mesenteric artery Spermatic arteries Inferior mesenteric artery Renal arteries . i Common iliac arteries . Internal iliac artery Ischiatic Internal pudic artery External iliac artery ~ Femoral artery . ‘ Popliteal artery . Anterior tibial artery Dorsalis pedis artery. . Posterior tibial artery . Peroneal artery Plantar arteries . . ; Pulmonary artery z xi xii CONTENTS. CHAPTER VI. THE VEINS. Page . age General anatomy . 366 | Veins of the trunk—continued. Veins of the head andneck . . 368 Superior venacava . + + 379 Veins of the diploé - 369 Iliac veins oie - « 880 Cerebral and cerebellar veins 370 Inferior vena cava . 8 - 381_ Sinuses of the dura mater . - 370 Azygos veins. - 382 Veins of the neck : . 374 Vertebral and spinal yeins . 383 Veins of the upper extremity - 875 Cardiac veins. eh iaie . 884 Veins of the lower extremity . 377 Portalven . + + . 384 Veins of the trunk ; * . 379 Pulmonary veins ‘ ¢ . 386 Venz innominate . . - 379 CHAPTER VII. THE LYMPHATICS. Page Page General anatomy . é ‘ - 387 Lymphatics of the trunk 3 - 392 Lymphatics of the head and neck 389 | Lymphatics of the viscera . - 304 Lymphatics of the upper extre- Lacteals:.6 We oe pe mity . 390 Thoracic duct 5 y . 206 Lymphatics of the lower extre- Ductus lymphaticus dexter. 397 0S ae a ah CHAPTER VIII. THE NERVOUS SYSTEM. Page Page General anatomy : i - 399 Diverging fibres . ; a . 427 The brain » 405 Converging fibres; commissures 430 Membranes of the ‘encephalon - 405 | Spinal cord . : t : - 431 Dura mater. ‘ - 406 | Cranial nerves. > : . 434 Arachnoid membrane - + 408 | Spinal nerves . Pre ikee + 455 Pia mater x ; - 409 Cervical plexus : ‘ - 457 Cerebrum . ae - 410 Brachial plexus : 459 Lateral ventricles. : - 411 Dorsal nerves . ° 466 Fifth ventricle . : 5. dees Lumbar nerves - ; - 468 Third ventricle é . - 417 Sacral nerves . . . 474 Fourth ventricle 419 Sympathetic — > ° . 480 Lining membrane of the ventri- Cranial ganglia . ‘ » 480 cles. . : ‘ + 420 Cervical ganglia ‘ ‘ » 485 Cerebellum... ° . + 420 Thoracic ganglia. 4 - 488 Base of the brain Sabie ue een Lumbar ganglia :. ‘ + 489 Medulla oblongata . . . 426 Sacral ganglia. . . + 490 CHAPTER IX. ORGANS OF SENSE. Page Page MO Bes as): . apie + + 491 | Eyeball—continued. Wasalfoesse . 0.6) ww 8 Retina; zonula ciliaris ~ - 499 Eyeball sforn Humours . - oy 601 } Sclerotic coat and cornea... 494 Physiological observations - 502 Choroid coat; ciliary ligament; Appendages of the eye 2%. 508 iis . . + « « 496 | Lachrymalapparatus . . . 505 CONTENTS. xiii Page Page Organ of hearing . - 506 | Organ of hearing tinued. External ear; pinna - 506 Cochlea 515 Meatus auditorius % ‘ - 508 Membranous labyrinth 517 Tympanum . . - 508 Organ of taste—Tongue 519 Ossicula audits - 508 | Organ of touch—Skin ; 521 Muscles of the ar toon _ + 510 | Appendages of the skin—Nails 525 Internal ear—Vestibul - 613 Hairs—Sebaceous glands 526 Semicircular canals . 514 Sudoriparous glands . 528 CHAPTER X. THE VISCERA. Page Page THORAX. : 4 d «590 1 a ans I ga Heart . a " - 530 Liver 574 Fibres of the heart F 538 Gall-bladder 584 Organs of respiration and voice 541 Pancreas . 585 —Cartilages . 541 Spleen. 586 Ligaments— Muscles 542 Supra-renal capsules 587 Trachea and Bronchi 548 Kidneys . 588 Thyroid si . F : 549 | PELVIS ae) fot; nen 592 Lungs reahye 550 Bladder ‘ 592 Pleurze 552 Prostate gland : : - 595 Mediastinum . 553 Vesiculze seminales . 596 ABpoMEN—Regions 553 MALE ORGANS OF GENERATION 507 Peritoneum 554 Penis : 2 507 Alimentary canal 559 Urethra . ‘i . 599 Lips-—Cheeks—Gums—Palate 560 Testes : : 601 Tonsils—Fauces ‘ . 561 FEMALE PELVIS. 606 Salivary pea p - 561 Bladder— Urethra - 606 Pharynx 5 . 563 Vagina . 3 3 ‘ ~« 606 Stomach : Z : . 564 Uterus . ; ‘ . 607 Small intestine . 565 Fallopian tubes. 611 Large intestine. . 566 Ovaries » Gi Structure of the intestinal canal 568 External organs of generation . 612 MAMMARY GLANDS . - 614 CHAPTER XI. ANATOMY OF THE FETUS. Page Page Osseous and ligamentous sania: 616 Feetal lungs ; d ; i 628 Muscular system . - 616 Feetal heart . zd . 624 Vascular system . F . » 616 Viscera of the abdomen : - 624 Feetal circulation . ‘ - 616 oO ic vessels . 624 Nervous system. . 619 Liver 625 Organs of Sense — Eye — Ear— Kidneys and supra-renal ea capsules 625 - Nose. ; . 620 | Viscera of the pelvis . 625 Thyroid gland 620 Testes—Descent 626 Thymus gland 620 TABLE OF ILLUSTRATIONS. Figs. Page 1. Intimate structure of bone 3 - Development of bone 6 3. Id. id. 2 2 6 4. Id. id. x a 7 5. Cervical vertebra. ; 11 6. Atlas ° ° Pakiite + 12 7. Axis . ° ; > ao 8. Dorsal vertebra : 14 9. Lumbar vertebra. ; 15 10. Sacrum . “ ; 4 ast) 11. Occipital bone — External sur- face «. 5 ; : , “a1 12. Occipital bone — Internal sur- : ; . . 2a 13. Parietal bone — External sur- face. 4 ‘ : - m4 14. Parietal bone — Internal sur- face. ‘ ° : Age 15. Frontal bone — External sur- face. ; x si ae 16. Frontal bone — Internal sur- : ‘ z : - 28 17. Temporal bone—External sur- face. . : : ie 18. Temporal bone—Internal sur- face. RET . “Sie? | 19. Meatus auditorius externus and internus, and tympanic bone 33 20. Sphenoid bone—Superior sur- face 36 21. Sphenoid ‘bone — Antero-infe- rior surface . : 37 22. Ethmoid bone . " - 40 23. Superior maxillary bone. . 42 24. Lachrymal bone 4 45 25. Palate bone — Internal | sur- face 46 26. Palate bone - : External sur- face. i 48 27. Inferior maxillary bone 51 28. Skull, anterior view . 54 29. layer - the skull; internal 55 30. Base “of the skull ; external . 58 31. Nasal fossa with the turbinated mes . ‘ 62 32. Os hyoides 5 71 Bee RMU Ea ie 73 > . Id. . Ligaments of the wrist and Ulna and radius : Bones of the ad ca posterior view. . . Hand; anterior view BS 6 innominatum 4 - Female pelvis ; anterior view . . Femur; anterior view . a . Femur; . Tibia an fibula; anterior view . Tibia and fibula; Seek osterior view . Foot; dorsal surface . Foot; plantar surface | Articular cartilage . . Reticular cartilage . . Fibrous cartilage . : Ligaments of the vertebree and ribs; anterior view : Posterior common ligament . . Ligamenta subflava . Ligaments of the atlas, axis, and occipital | bone . Id.; posterior view . Id:; internal view : ; Id.; internal view . , Ligaments of the lower j jaws ; external view . Id.; internal view . , Id ; section . : Ligaments of the vertebral column and ribs . - Ligaments of the pelvis and . Id; . Ligaments of the sternal end ip-joint . ° Id. of the clavicle and costal cartilages . . Ligaments of the scapula and shoulder-joint . Ligaments of the elbow in- ternal view . External view . hand. . . Synovial membranes of the wrist . Knee joint; anterior view . Id.; posterior view - Muscles - Muscles o TABLE OF ILLUSTRATIONS. 3 Knee-joint; internal view - . . Id.; reflexions of the — vial membrane . é eee internal view . Id; 3 Ligaments of the sole of the external view . posterior view .« foot - Minute structure of musele é . Minute structure of muscle . b ee, structure of — d . ik . Muscles of the face ‘ = . Muscles of the orbit . . Pterygoid muscles id. a r! id. 4 z Muscies of the neck ; super- ficial and deep ‘ : - Muscles of thet tongue . + Muscles of the pharynx j - Muscles of the soft palate . acter of the pines 5 Muscles of the back; Ist ond, and 3rdlayer . Muscles of the back ; "deep layer. . of the aspect of the trunk Muscles of the lateral aspect ofthetrunk . anterior - Diaphragm . : . Muscles of the perineum Muscles of. the anterior hu- meral region . ——- cxtaaie cubiti . pe layer of muscles he anterior aspect of the fore-arm - Deep layer of muscles of the anterior aspect of the fore- arm : Superficial layer of muscles ; posterior aspect of the fore- arm . Deep layer ; posterior aspect of the fore arm . . Muscles of the hand, ‘ante- rior aspect . . Mosca, of the gluteal re- gion, deep layer . the anterior and internal femoral region. . Muscles of the gluteal and posterior femoral region . Muscles of the anterior tibial region . Muscles of the posterior ‘tibial on regi . Muscles of the posterior ‘tibial region, deep layer Page 150 151 153 216 223 233 235 Figs. 109. 110. 111. Muscles of the sole of the foot:. 1st layer . é a »» 2nd layer. i Section of the els showing the distribution of the deep cervical fascia . Transverse section of the elvis, showing the distri- uution of the fascize . . Deep perineal fascia . Distribution of the deep peri- neal fascia, side'view . ‘ Distribution -of the fasciee ; ; at the femoral arch . - The great vessels of the chest . Branches of the external carotid arte Ty . gp sani of the ‘subclavian artery - The circle of Willis and brachial or- teries . . Arteries of the fore-arm — Radial and ulnar . Branches of the abdominal aorta . . Coeliac axis with its branches . The superior mesenteric arte ry. . : A . . The inferior mesenteric ar- tery . The internal iliac artery with its branches . The arteries of the perineum . The femoral artery, with its branches . The anterior tibial artery i - Posterior tibial and peroneal artery . Arteries of the sole of the foot . A . Sinuses of the dura mater . Sinuses of the base of the skull . Veins and nerves of the bend of the elbow A . Veins of the trunk and neck - The portal vein. . . The thoracic duct. 4 . Minute structure of nerve . . The lateral ventricles of the cerebrum - Longitudinal sect section - the rain . Base of the brain . Distribution of the fibres of the brain ; . The olfactory nerve - Origin of the optic and fourth nerves. . Trifacial or fifth nerve } 2 pes TABLE OF ILLUSTRATIONS. igs. . Facial and cervical nerves s Hy poe pair of nerves . glossal or ninth nerve . plexus and nerves of the upper extremi . Lumbar and sacral p exus, with the nerves of the lower extremity . . ip cranial ganglia of the pathetic nerve o-cartilages of the nose « itudinal section of the globe of the eye . A transverse section of the globe of the eye . . Another transverse section of the globe of the eye . A diagram of the ear . Anatomy of the cochlea . Osseous and membranous labyrinth of the ear . . . Anatomy of the skin - Development of epidermis - Anatomy of the skin The heart . Ligaments of the larynx . Muscles of the larynx . - Muscles of the larynx . Page 446 451 453 | 462 ° P . Anatomy of the lungs and heart . = ¥ , 3 The peritoneum . The pharynx . Anatomy of the stomach and duodenum . . The liver; its up ner surface . The liver; . Lobules of the liver . Lobules of the liver . Section of the kidney - u . Plan of the renal circulation. . A side view of the viscera of its under surface the male pelvis . . A posterior view of the "blad- er and vesiculze seminales . Anatomy of the urethra e . Transverse section of the testicle ‘ » 5 Anatomy of the testis ‘ A side view of the viscera of the female pelvis. J 3 . Feetal circulation . ‘ . Section of the thymus gland - Ducts of the thymus gland i. Poo of the testis in the fetus. . ‘ THE ANATOMIST’S VADE MECUM. CHAPTER IL. OSTEOLOGY. THE bones are the organs of support to the animal frame ; they give firmness and strength to the entire fabric, afford points of con- nection to the numerous muscles, and bestow individual character upon the body. In the limbs they are hollow cylinders, admirably calculated by their conformation and structure to resist violence and support weight. In the trunk and head, they are flattened and arched, to protect cavities and provide an extensive surface for attachment. In some situations they present projections of variable length, which serve as levers ; and in others are grooved into smooth surfaces, which act as pulleys for the passage of tendons. Moreover, besides supply- ing strength and solidity, they are equally adapted, by their numerous divisions and mutual apposition, to fulfil every movement which may tend to the preservation of the creature, or be conducive to his welfare. According to the latest analysis by Berzelius, bone is composed of about one-third of animal substance, which is almost completely redu- cible to gelatine by boiling, and of two-thirds of earthy and alkaline salts. The special constituents are present in the following propor- tions :— Cartilage . ‘ . ; » . 82°17 parts. Blood-vessels . . ‘ ‘ ; 113 Phosphate of lime ; ‘ ; ~ 61°04 Carbonate of lime . ‘ ‘ ‘ 11°30 Fluate of lime . : ‘ : é 2 Phosphate of magnesia; : : 1°16 Soda, Chloride of sodium . ‘ . 1°20 100°00 B 2 STRUCTURE OF BONE. Bones are divisible into three classes :—Long, flat, and irregular. The Zong bones are found principally in the limbs, and consist of a shaft and two extremities. The shaft is cylindrical or prismoid in form, dense and hard in texture, and hollowed in the interior into a medullary canal. The extremities are broad and expanded, to articu- late with adjoining bones ; and cellular or cancellous in internal struc- ture. Upon the exterior of the bone are processes and rough surfaces for the attachment of muscles, and foramina for the transmission of vessels and nerves. The character of long bones is, therefore, their general type of structure and their divisibility into a central portion and extremities, and not so much their length ; for there are some long bones, as the second phalanges of the toes, which are less than a quarter of an inch in length, and almost equal, and in some instances exceed, in breadth their longitudinal axis. The long bones are, the clavicle, humerus, radius and ulna, femur, tibia and fibula, metacarpal bones, metatarsal, phalanges and ribs. Flat bones are composed of two layers of dense bone with an inter- mediate cellular structure, and are divisible into surfaces, borders, angles, and processes. They are adapted to enclose cavities ; have processes upon their surface for the attachment of muscles ; and are perforated by foramina, for the passage of nutrient vessels to their cells, and for the transmission of vessels and nerves. They articulate with long bones by means of smooth surfaces plated with cartilage, and with each other either by fibrous tissue, as at the symphysis pubis ; or by suture, as in the bones of the skull. The two condensed layers of the bones of the skull are named, tables ; and the intermediate cellular structure, diplée. The flat bones are the occipital, parietal, frontal, nasal, lachrymal, vomer, sternum, scapula, and ossa inno- minata, The Irregular bones include all that remain after the long and the flat bones have been selected. They are essentially irregular in their form, in some parts flat, in others short and thick. In preceding edi- tions of this work the short and thick bones were made a separate class under the name of short bones. This subdivision has been found to be disadvantageous, besides being arbitrary, and is, therefore, now omitted. Irregular bones are constructed on the same general princi- ples with other bones ; they have an exterior dense, and an interior more or less cellular. The bones of this class are, the temporal, sphe- noid, ethmoid, superior maxillary, inferior maxillary, palate, inferior turbinated, hyoid, vertebra, sacrum, coccyx, carpal and tarsal bones, and sesamoid bones, including the patella. Structure of Bone.—Bone is a dense, compact, and homogeneous sub- stance (basis substance) filled with minute cells, (corpuscles of Purk- inje) which are scattered numerously through its structure. The basis substance of bone is subfibrous and obscurely lamellated, the lamellz being concentric in long and parallel in flat bones ; it is traversed in all directions, but especially in the longitudinal axis, by branching and inosculating canals (Haversian canals) which give passage to vessels STRUCTURE OF BONE. Fig. 1.* and nerves, and in certain situations the lamellze separate from each other, and leave between them areolar spaces (cancelli) of various magnitude. The lamellae have an average diameter of g@55 of an inch, and besides constituting the general structure of the basis sub- stance, are collected concentrically around the Haversian canals, and form boundaries to those canals of about 54, of an inch in thickness. The number of lamellz surrounding each Haversian canal, is commonly ten or fifteen, and the diameters of the canals have a medium average of 34, of an inch. The cancelli of bone like its compact substance have walls which are composed of lamellz, and such is the similarity in structure of the parts of a bone, that the entire bone may be com- pared to an Haversian canal of which the medullary cavity is the mag- nified channel ; and the Hayersian canals may be likened to elongated and ramified cancelli. The Haversian canals are smallest near the * Minute structure of bone, drawn with the miscroscope from nature, by Bagg. Magnified 300 diameters. 1. One of the Haversian canals surrounded by its concentric lamellz. The corpuscles are seen between the lamelle; but the calcigerous tubuli are omitted. 2. An Haversian canal with its concentric lamellee, Purkinjean ee and tubuli. 3. The area of one of the canals. 4, 4. Direction of the lamelle of the great medullary canal. Between the lamellee at the upper part of the figure, several very long corpuscles with their tubuli are seen. In the lower part of the figure, the outlines of three other canals are given, in order to show their form and mode of arrangement in the entire bone. 4 DEVELOPMENT OF BONE. surface of a bone, and largest near its centre, where they gradually merge into cancelli ; by the frequent communications of their branches they form a coarse network in the basis substance. The cells of bone, or corpuscles of Purkinje, are thickly disseminated through the basis substance ; they are irregular in size and form, give off numerous minute branching tubuli which radiate from all parts of their circumference, and in the dried state of the bone contain merely the remains of membranous cells and some calcareous salts.* In the living bone the cells and their tubuli are probably filled with a nutri- tive fluid holding calcareous salts in solution. The form of the cells is oval or round and more or less flattened, their long diameter corre- sponds with the long axis of the bone, and their tubuli cross the direc- tion of the lamelle and constitute a very delicate network in the basis substance by communicating with each other, and with the tubuli of neighbouring cells. The tubuli of the cells nearest the Haversian canals terminate upon the internal surface of those cavities. The size of the cells varies in extreme measurement from s7y45 to gdp of an inch in their long diameter, an ordinary average being z,55; the breadth of the oval cells is about one half or one third their length, and their thickness one half their breadth. They are situated between the lamellee, to which circumstance they owe their compressed form. In the fresh state, bones are invested by a dense fibrous membrane, the periosteum, which covers every part of their surface with the ex- ception of the articular extremities, the latter being coated by a thin layer of cartilage. The periosteum of the bones of the skull is termed pericranium ; and the analogous membrane of external cartilages, peri- chondrium. Lining the interior of the medullary canal of long bones, the Haversian canals, the cells of the cancelli, and the cells of short, flat, and irregular bones, is the medullary membrane, which acts as an in- ternal periosteum. It is through the medium of the vessels ramifying in these membranes that the changes required by nutrition occur in bones, and the secretion of medulla into their interior is effected. The medullary canal, Haversian canals and cells of long bones, and the cells of other bones, are filled with a yellowish oily substance, the medulla, which is contained in a loose areolar tissue formed by the medullary membrane. Development of Bone.—To explain the development of bone it is ne- cessary to inform the student that all organised bodies, whether belong- ing to the vegetable or the animal kingdom, are developed primordially from minute vesicles. These vesicles, or, as they are commonly termed, cells, are composed of a thin membrane containing a fluid or granular matter, and a small rounded mass, the zwclews, around which the cell was originally formed. Moreover, the nucleus generally con- tains one or more small round granules, the zweleolus or nucleoli. From cells having this structure all the tissues of the body are elaborated ; * Miiller and Henle conceived that the bone cells and tubuli were the prin- sont four Jue’ = calcareous matter. Hence they have been named calcigerous DEVELOPMENT OF BONE, 5 the ovum itself originally presented this simple form, and the embryo at an early period is wholly composed of such nucleated cells. In their relation to each other, cells may be isolated and independent, as is exemplified in the corpuscles of the blood, chyle and lymph; secondly, they may cohere by their surfaces and borders, as in the epidermis and epithelium ; thirdly, they may be connected by an intermediate substance which is then termed intercellular, as in cartilage and bone ; and fourthly, they may unite with each other in rows, and upon the removal by liquefaction of the adherent surfaces be converted into hollow tubuli. In the latter mode capillary vessels are formed, as also are the tubuli of nerve and muscular fibre. One of the properties of cells may also be adverted to in this place; it is that of reproducing similar cells in their interior. In this case the nucleoli become the nuclei of the secondary cells, and as the latter increase in size, the membrane of the primary or parent cell is lost. Bone, in its earliest state, is composed of an assemblage of these minute cells, which are soft and transparent, and are disposed within the embryo in the site of the future skeleton. From the resemblance which the soft tissue bears to jelly, this has been termed the gelatinous stage of osteo-genesis. As development advances, the cells, heretofore loosely collected together, become separated by the interposition of a transparent intercellular substance, which is at first fluid, but gradually becomes hard and condensed. The cartilaginous stage of osteogenesis is now established, and cartilage is shown to consist of a transparent matrix, having minute cells disseminated at pretty equal distances and without order through its structure. Coincident with the formation of cartilage is the development of vascular canals in its substance, the canals being formed by the union of the cells in rows, and the subse- quent liquefaction of the adhering surfaces. The change which next ensues is the concentration of the vascular canals towards some one point ; for example, the centre of the shaft in a long, or the mid-point of a flat bone, and here the punctum ossificationis or centre of ossifica- tion is established. What determines the vascular concentration now alluded to, is a question not easily solved, but that it takes place is certain, and the vascular punctum is the most easily demonstrable of all the phenomena of ossification. During the formation of the punctum ossificationis, changes begin to be apparent in the cartilage cells. Originally they are simple nucleated cells (sy'5g tO soap Of an inch in diameter), having a rounded form. As growth proceeds, they become elongated in their figure, and it is then perceived that each cell contains two and often three nucleoli around which smaller cells are in progress of formation.. If we ex- amine them nearer to the punctum ossificationis we find that the young or secondary cells have each attained the size of the parent cell (sg55 of an inch), the membrane of the parent cell has disappeared, and the young cells are separated to a short distance by freshly effused inter- cellular substance. Nearer still to the punctum ossificationis a more remarkable change has ensued, the energy of cellule reproduction has 6 DEVELOPMENT OF BONE. Fig. 2.* B “fhe ~ 4D. 4 ‘Y a of U3 3 2% ¥ Sr nD ©," 2 P p ? « Tah ® yt 2 af 2® «) 9 af Ce , we 2G 2 9° gba PS V2Beg a Rm We? 2 Bw” ea pati te acl? tae ® 7® @ @* To eer al Yow “9 gy, PO @ £ A a ® 1.98 S on 09 6) rf) 8 v a 3 mo) % re) ‘ 6 f a at GS 8 A Hh R) S Kp} Ag Cel . . . . . . l in ugmented with proximity to the ossifying point, and each cel plas of srodactng two, gives birth to four, five, or six young cells, AS oe BY “ton We, yy ats ig which rapidly destroy the parent membrane and attain a greater size (+ssy of an inch) than the parent cell, each cell being, as in the pre- vious case, separated to a slight extent from its neighbour by inter- * Figures illustrative of the development of bone; they are magnified 155 times, and drawn with the camera lucida. a. A portion of cartilage, the farthest removed from the seat of ossification, showing simple nucleated cells, having an ordinary size of B00 of an inch, long diameter. 3s. The same cartilage nearer to the seat of ossification ; each simple cell has produced two, which are a little larger than the cells in figure a. + The same cartilage, still nearer the seat of ossification; each single cell of B has given birth to four, five, or six cells, which form clusters. These clusters become larger towards the right of the figure, and their cells more numerous and larger, +s'5o of an inch, long diameter. DEVELOPMENT OF BONE. 7 cellular substance. By one other repetition of the same process, each cell producing four or five, or six young cells, a cluster is formed, con- taining from thirty to fifty cells. These clusters lie in immediate relation with the punctum ossificationis ; they are oval in figure (about sé in length by 53, in breadth), and placed in the direction of the longitudinal axis of the bone. The cells composing the cluster lie transversely with regard to its axis. In the first instance they are closely compressed, but by degrees are parted by a thin layer of inter- cellular substance, and each cluster is separated from neighbouring Fig. 4.* DS Da ee clusters by a broader layer (zs'55 of inch) of intercellular substance. Such are the changes which occur in cartilage preparatory to the for- mation of bone. _ Ossification is accomplished by the formation of very fine and deli- cate fibres within the intercellular substance: this process commences at the punctum ossificationis and extends from that point through every part of the bone, in a longitudinal direction in long, and in a radiated manner in flat bones. Starting from the punctum ossificationis, the fibres embrace each cluster of cells, and then send branches between the individual cells of each group. In this manner the network, characteristic of bone, is formed, while the cells by their conjunction * The same cartilage at the seat of ossification ; the clusters of cells are arranged in columns; the intercellular spaces between the columns being 3255 of an inch in breadth. To the right of the figure osseous fibres are seen occupying the intercellular spaces, at first bounding the clusters laterally, then splitting them longitudinally and encircling each separate cell. The greater opacity of the right hand border is due to a threefold cause, the in- crease of osseous fibres, the opacity of the contents of the cells, and the multi- plication of oil globules. In the lower part of the figure some attempt has been made to show the texture of the cells, 8 DEVELOPMENT UF BONE. constitute the permanent areola and Haversian canals. With a high magnifying power, the delicate ossific fibres here alluded to are seen themselves to be composed of minute cells having an elliptical form and central nuclei. These cells attract into their interior the cal- cerous salts of the blood, and their nuclei become developed, as I believe, into the future corpuscles of Purkinje. It is possible also that some of the cartilage cells become corpuscles of Purkinje in the fully developed bone. During the progress of the phenomena above described, the contents of the cells undergo certain changes. At first, their contents are transparent, then they become granular, and still later opaque, from the presence of amorphous matter mingled with nuclei, nucleoli, and the remains of secondary cells. In the latter state they also contain an abundance of minute oil-globules. These latter increase in size as the ossific changes advance, and in the newly formed osseous areolz they are very numerous and have attained the ordinary size of adipose cells, Cartilaginification is complete in the human embryo at about the sixth week; and the first point of ossification is observed in the clavicle at about the seventh week. Ossification commences at the centre, and thence proceeds towards the surface ; in flat bones the osse- ous tissue radiates between two membranes from a central point to- wards the periphery, in short bones from a centre towards the circum- ference, and in long bones from a central portion, diaphysis, towards a secondary centre, epiphysis, situated at each extremity. Large pro- cesses, as the trochanters, are provided with a distinct centre of development, which is named apophysis. The growth of bone in length takes place at the extremity of the diaphysis, and in bulk by fresh deposition on the surface; while the medullary canal is formed and increased by absorption from within. The period of ossification is different in different bones; the order of succession may be thus arranged :— During the fifth week, ossification commences in the clavicle, lower jaw, and upper jaw. During the sixth week, in the femur, humerus, tibia, radius, and a. During the seventh and eighth weeks, in the fibula, frontal, occi- pital, sphenoid, ribs, parietal, temporal, nasal, vomer, palate, vertebrae, three first pieces of sacrum, malar, metacarpus, metatarsus, third phalanges of the hands and feet, and ilium. During the third month, in the first and second phalanges of the hands and féet, lachrymal bone, and ischium. During the fifth month, in the mastoid portion of the temporal, ethmoid, inferior turbinated, sternum, os pubis, and two last pieces of sacrum, During the sixth month, in the body and odontoid process of the axis, and calcaneus. PERIODS OF OSSIFICATION. 9 During the seventh month, in the astralagus. During the tenth month, in the cuboid bone and os hyoides. During the first year, in the coracoid process of the scapula ; first piece of the coccyx, inferior turbinated bone, last piece of the sternum, anterior arch of the atlas, os magnum, os unciforme, and external cunei- form bone. During the third year, in the cuneiform of the carpus, internal cuneiform, and patella. During the fourth year, in the middle cuneiform and scaphoid of the tarsus. During the fifth year, in the trapezium and os semilunare. During the seventh year, in the second piece of the coccyx. During the eighth year, in the scaphoid of the carpus. During the ninth year, im the os trapezoides. During the twelfth year, in the os pisiforme and third piece of the coccyx. During the eighteenth year, in the fourth piece of the coccyx. The ossicula auditis are the only bones completely ossified at birth ; the vertebrae are not completed until the five and twentieth year. The entire osseous framework of the body constitutes the skeleton, which in the adult man is composed of two hundred and forty-six dis- tinct bones. They may be thus arranged :— Head : A - j eae Ossicula audiths / ; : ; ; 6 Face - ‘ , : ‘ ae F Teeth . : i 32 Vertebral column, including sacrum and coccyx 26 Os hyoides, sternum, and ribs. ; 2°26 Upper extremities . ‘ : ‘ : 64 Lower extremities . ‘ : A . 62 Sesamoid bones . 5 . : : 8 246 The skeleton is divisible into: 1. The vertebral column or central axis. 2. The head and face, or superior development of the central axis. 3. The hyoid arch. 4. The thoracic arch and upper ex- tremities. 5. The pelvic arch and lower extremities. 10 VERTEBRAL COLUMN. The vertebral column is the first and only rudiment of internal skeleton in the lower Vertebrata, and constitutes the type of that great division of the animal kingdom. It is also the first developed portion of the skeleton in man, and the centre around which all the other parts are produced. In its earliest formation it is a simple cartilaginous cylinder, surrounding and protecting the primitive trace of the nervous system ; but, as itadvances in growth and organi- sation, it becomes divided into distinct pieces, which constitute vertebra. The vertebre are divided into true and false. The true vertebre are twenty-four in number, and are classified, according to the three regions of the trunk which they occupy, into cervical, dorsal, and lumbar. The false vertebrae consist of nine pieces united into two bones, the sacrum and coccyx. The arrangement of the vertebree may be better comprehended by means of the accompanying table :— 7 Cervical, True vertebrae 24 12 Dorsal, 5 Lumbar. 5 Sacrum False vertebrae 9 ! 4 Coccyx. Characters of a Vertebra——A vertebra consists of a body, two lamin, a spinous process, two transverse processes, and four articular processes. The body is the solid part of the vertebra ; and, by its arti- culation with adjoining vertebrae, gives strength and support to the trunk. It is flattened above and below, convex in front, and slightly concave behind. Its anterior surface is constricted around the middle, and pierced by a number of small openings which give passage to nutritious vessels. Upon its posterior surface is a single irregular opening, or several, for the exit of the vene basis vertebre. The amine commence upon the sides of the posterior part of the body of the vertebra by two pedicles ; they then expand ; and, arching backwards, enclose a foramen which serves for the protection of the spinal cord. The upper and lower borders of the laminz are rough — for the attachment of the ligamenta subflava. The concavities above and below the pedicles are the intervertebral notches. The spinous process stands backwards from the angle of union of the laminz of the vertebra. It is the succession of these projecting processes along the middle line of the back, that has given rise to the common designation of the vertebral column, the spine. The use of the spinous process is for the attachment of muscles. The transverse processes project one at each side from the lamin of the vertebra ; they are intended for the CERVICAL VERTEBRZ. ll attachment of muscles. The articular processes, four in number, stand upwards and downwards from the laminz of the vertebra to articulate with the vertebra above and below. Cervical Vertebre.—In a cervical vertebra the body is smaller than in the other regions ; it is thicker be- fore than behind, broad from side to side, concave on the upper surface, and convex below ; so that when arti- culated, the vertebree lock the one into the other. The lamine are narrow and long, and the included spinal JSoramen large and triangu- lar. The superior interver- tebral notches are slightly deeper than the inferior; the inferior being the broadest. The spinous process is short and bifid at the extremity, increasing in length from the fourth to the seventh. The transverse processes are also short and bifid, and deeply grooved along the upper surface for the cervical nerves. Piercing the base of the transverse process is the vertebral foramen which gives passage to the vertebral artery and vein, and vertebral plexus of nerves. The transverse processes in this region, are formed by two small developments which proceed, the one from the side of the body, the other from the pedicle of the vertebra, and unite near their extremities to enclose the circular area of the vertebral fora- men. The anterior of these developments is the rudiment of a cervi- cal rib ; and the posterior, the analogue of the transverse processes in the dorsal region. The extremities of these developments are the anterior and posterior tubercles of the transverse process. The articular processes are oblique ; the superior looking upwards and backwards ; and the inferior, downwards and forwards. There are three peculiar vertebrae in the cervical region :—The first or atlas ; the second or axis; and the seventh or vertebra promi- nens. The Ad/as (named from supporting the head) is a simple ring of bone, without body and composed of arches and processes. The an- Fig. 5.* * A central cervical vertebra, seen upon its upper surface. 1. The body, concave in the middle, and rising on each side into a sharp ridge. 2. The lamina. 3. The pedicle rendered concave by the superior intervertebral notch. 4. The bifid spinous process. 5. The bifid transverse process. The figure is placed in the concavity between the anterior and posterior tubercles, between the two processes which correspond with the rudimentary rib and the true transverse process. 6. The vertebral foramen. 7. The superior articular pro- cess, looking backwards and upwards. 8. The inferior articular process. + Sometimes, as in a vertebra now before me, a small additional opening exists by the side of the vertebral foramen, in which case it is traversed by a second vein. 12 ATLAS AND AXIS. terior arch has a tu- bercle on its anterior Fig. 6.* surface, for the attach- ment of the longus colli muscle ; and on its pos- terior aspect is a smooth surface, for the articula- tion of the odontoid process of the axis. The posterior arch is longer and more slender than the anterior, and flattened from above downwards ; at its mid- dle is a rudimentary spinous process ; and upon its upper surface, near the articular pro- cesses, a shallow groove + at each side, which represents a superior intervertebral notch, and supports the vertebral artery previously to its passage through the dura mater, and the first cervical nerve. The intervertebral notches are peculiar from being situated behind the ar- ticular processes instead of before them, as in the other vertebra. The transverse processes are remarkably large and long, and pierced by the foramen for the vertebral artery. The articular processes are situated upon the most bulky and strongest part of the atlas. The superior are oval and concave, and look inwards, so as to form a kind of cup for the condyles of the occipital bone, and are adapted to the nodding movements of the head ; the inferior are circular, and nearly horizon- tal, to permit of the rotatory movements. Upon the inner face of the lateral mass which supports the articular processes, is a small tubercle at each side, to which the extremities of the transverse ligament are attached, a ligament which divides the ring of the atlas into two un- equal segments ; the smaller for receiving the odontoid process of the axis, and the latter to give passage to the spinal cord and its mem- branes. The Aas (vertebra dentata) is so named from having a process upon which the head turns as on a pivot. The body is of large size, and supports a strong process, the odontoid, which rises perpendicularly from its upper surface. The odontoid process presents two articulating surfaces ; one on its anterior face, to articulate with the anterior arch of the atlas ; the other on its posterior face, for the transverse liga- * The upper surface of the atlas. 1. The anterior tubercle projecting from the anterior arch. 2. The articular surface for the odontoid process upon the posterior surface of the anterior arch. 3. The posterior arch, with its rudi- mentary spinous process. 4. The intervertebral notch. 5. The transverse process. 6. The vertebral foramen. 7. Superior articular surface. 8. The tubercle for the attachment of the transverse ligament. The tubercle referred to is just above the head of the figure; the convexity below it is the margin of the inferior articulating process. + This groove is sometimes converted into a foramen. VERTEBRA PROMINENS. 13 ment ; the latter surface constricts the base of the process which has given rise to the term eck applied to this part. Upon each side of its apex is a rough depression, for the attachment of the alar ligaments ; and running down from its base on the anterior surface of the body of Fig. 7.* the vertebra a vertical ridge, with a y depression at each side for the at- tachment of the longus colli muscle. The damine are large and strong, and unite posteriorly to form a long and bifid spinous process, which is concave beneath. The transverse processes are quite rudimentary, not bifid, and project only so far as to enclose the vertebral foramen, which is directed obliquely out- wards instead of perpendicularly as in the other vertebre. The sw- perior articulating processes are situated upon the body of the vertebra on each side of the odontoid process. They are circular and nearly horizontal, having a slight inclination outwards. The inferior articu- lating processes look downwards and forwards, as do the same processes in the other cervical vertebra. The superior intervertebral notch is remarkably shallow, and lies behind the articular process as in the atlas. The lower surface of the body is convex, and is received into the concavity upon the upper surface of the third vertebra. The Vertebra prominens, or seventh cervical, approaches in character to the upper dorsal vertebrae. It has received its designation from having a very long spinous process, which is single and terminated by a tubercle, and forms a considerable projection on the back part of the neck ; to the extremity of this process the ligamentum nuche is at- tached. The transverse processes are but slightly grooved along the upper surface, have each a small foramen for the transmission of the vertebral vein, and present only a rudimentary bifurcation at their extremity. Sometimes the anterior tubercle represents a small but distinct rib. Dorsal Vertebrea.—The body of a dorsal vertebra is as long from before backwards as from side to side, particularly in the middle of the dorsal region ; it is thicker behind than before, and marked on each side by two half-articulating surfaces for the heads of two ribs. The mK Cy * A lateral view of the axis. 1. The body, the figure is placed on the de- pression which gives attachment to the longus colli, 2. The odontoid process. 3. The smooth facet on the anterior surface of the odontoid process which arti- culates with the anterior arch of the atlas; the facet for the transverse ligament is beneath No. 2, where the constriction called the neck of the odontoid process is seen; the bulk of the process between 2, 3, would represent its head. 4. The lamina. 5. The spinous process. 6. The transverse process pierced ob- a ser by the vertebral foramen. 7. The superior articular surface. 8. The inferior articular process. 14 DORSAL VERTEBR2. pedicles are strong, and the lamine broad and thick ; the spinal fora- men small and round, Fig. 8* and the inferior inéer- vertebral notch of large size, the superior can scarcely be said to exist. The spinous process is long, prismoid, directed very obliquely down- wards, and terminated by a tubercle. The transverse processes are large and strong, and directed obliquely back- wards. Upon the an- terior and superior as- pect of their summits is a small facet for the articulation of the tubercle of a rib. The articular processes are vertical, the superior facing directly backwards, and the inferior di- rectly forwards. The peculiar vertebrae in the dorsal region are the first, ninth, tenth, eleventh, and twelfth. The jirst dorsal ‘vertebra approaches very closely in character to the last cervical. The body is broad from side to side, and concave above. The superior articular processes are oblique, and the spinous process horizontal. It has an entire articular surface for the first rib, and a half surface for the second. The minth dorsal vertebra has only one half articular surface at each side. The tenth has a single entire articular surface at each side. The eleventh and twelfth have each a single entire articular surface at each side ; they approach in character to the lumbar vertebra ; their transverse processes are very short, trifid at their summits, and have no articu- lation with the corresponding ribs. The transverse processes of the twelfth dorsal vertebra are quite rudimentary, and its inferior ar- ticular processes look outwards. Lumbar Vertebre.—These are the largest pieces of the vertebral column. The body is broad and large, and thicker before than behind. The pedicles very strong ; the /amine short, thick, and broad; the in- ferior intervertebral notches very large, and the spinal foramen large and oval... The spinous process is thick and broad. The transverse processes (costiform processes) are slender, pointed, and directed only slightly backwards. The superior articular processes are concave, and * A lateral view of a dorsal vertebra. 1. The body. 2, 2. Articular facets for the heads of ribs. 3. The pedicle, 4. The superior intervertebral notch. 5. The inferior intervertebral notch. 6, The spinous process. 7. The ex- tremity of the transverse process marked by an articular surface for the tubercle ofarib. 8. The two superior articular processes looking backwards. 9. The two inferior articular processes looking forwards. LUMBAR VERTEBRZ. 15 look backwards and in- Fig. 9.* wards ; the inferior, con- vex, and look forwards and outwards. Project- ing backwards and up- wards from the supe- rior articular process is a short and flattened tu- bercle or posterior trans- verse process, and in a strongly marked verte- bra there is not unfre- quently at the base of this a smaller tubercle which has a direction - downwards. The last lumbar vertebra differs from the rest in having the body very much bevelled posteriorly, so as to be broad in front and narrow behind, and the transverse process thick and e. General Considerations.—Viewed as a whole, the vertebral column represents two pyramids applied base to base, the superior being formed by all the vertebree from the second cervical to the last lum- bar, and the inferior by the sacrum and coccyx. Examined more at- tentively, it will be seen to be composed of four irregular pyramids, applied to each other by their smaller extremities and by their bases. The smaller extremity of the uppermost pyramid is formed by the axis, or second cervical vertebra ; and its base, by the first dorsal. The second pyramid is inverted; having its base at the first dorsal, and the smaller end at the fourth. The third pyramid commences at the fourth dorsal, and gradually enlarges to the fifth lumbar. The fourth pyramid is formed by the sacrum and coccyx. ; The bodies of the vertebree are broad in the cervical region, nar- rowed almost to an angle in the middle of the dorsal, and again broad in the lumbar region. The arches are broad and imbricated in the cervical and dorsal regions, the inferior border of each overlapping the superior of the next ; in the lumbar region an interval is left between them. A considerable interval exists between the cranium and atlas, and another between the last lumbar vertebra and sacrum. The spinous processes are horizontal in the cervical, and become gradually oblique in the upper part of the dorsal region. In the middle of the dorsal region they are nearly vertical and imbricated, and towards its lower part assume the direction of the lumbar spines, which are quite horizontal. The transverse processes developed in * A lateral view of a lumbar vertebra. 1. The body. 2. The pedicle. 3. The superior intervertebral notch. 4. The inferior intervertebral notch. 5. The spinous process. 6. The transverse process. 7. The superior articular processes. 8. The inferior articular processes. 9. The posterior transverse process. 16 VERTEBRAL COLUMN, their most rudimentary form in the axis, gradually increase in length to the first dorsal vertebra. In the dorsal region they project obliquely backwards, and diminish suddenly in length in the eleventh and twelfth vertebrae where they are very small. In the lumbar region they increase to the middle transverse process, and again subside in length to the last. The transverse processes consist essentially of two parts, the ante- rior of which in the dorsal region is the rib, while the posterior retains the name of the transverse process. In the*cervical region these two elements are quite apparent, both by their different points of at- tachment to the vertebra, and by the vertebral foramen which divides them at their base. In the lumbar region the so-called transverse processes are, in reality, lumbar ribs, while the transverse processes will be found behind them in a rudimentary state, developed like the true transverse processes in the cervical region, from the superior ar- ticular processes. When the anterior and posterior transverse pro- cesses are examined in relation with each other, they will be observed to converge ; and if the latter were prolonged they would unite as in the cervical region and enclose a foramen, or they would rest in con- tact as in the dorsal region, or become consolidated as in the forma- tion of the sacrum. Moreover, the posterior transverse processes are directed upwards, and if they were prolonged, they would come into contact with a small tubercle which is found at the base of the poste- rior transverse process (in strongly marked vertebra) in the vertebra above. This junction would form a posterior intervertebral foramen, as actually occurs in the sacrum. . In brief, the lumbar vertebre ex- hibit those transitional changes which are calculated, by an easy gra- dation, to convert separate vertebree into a solid bone. The transverse processes of the eleventh and twelfth dorsal vertebra are very inte- resting in a transcendental point of view, as exhibiting a tendency which exists obscurely in all the rest, namely, to trifurcate. Now, supposing these three branches to be lengthened in order to fulfil their purposes, the anterior would constitute the articulation or union with a rib, while the superior and inferior would join similar branches in the vertebra above and below, and so form the posterior intervertebral foramen. The intervertebral foramina formed by the juxta-position of the notches, are smallest in the cervical region, and gradually increase to the last lumbar. On either side of the spinous processes, and extend- ing the whole length of the column, is the vertebral groove, which is shallow and broad in the cervical, and deeper and narrower in the = and lumbar regions. It lodges the principal muscles of the Viewed from the side, the vertebral column presents several curves, the principal of which is situated in the dorsal region, the concavity looking forwards. In the cervical and lumbar regions the column is convex in front ; and in the pelvis an anterior concave curve is formed by the sacrum and coccyx. Besides the antero-posterior curves, a SNOT DEVELOPMENT OF VERTEBRA. 17 slight lateral curve exists in the dorsal region, having its convexity towards the right side. Development.—The vertebree are developed by three primary and five secondary centres or epiphyses. The primary centres are, one for -each lamella, and one for the body ; the epiphyses, one for the apex of the spinous process, one for that of each transverse process, and one for the upper and under surface of the body. Exceptions to this mode of development are met with in the atlas, axis, vertebra pro- minens, and lumbar vertebree. The alas has four centres: one for each lateral mass, one (sometimes two) for the anterior arch, and one for the centre of the posterior arch. The avis has five: one (some- times two) for the body, two for the odontoid process, appearing side by side in its base, and one for each lamella. The vertebra prominens has two additional centres for the anterior or costal segments of the transverse processes, and the lumbar vertebre two for the posterior segments of the transverse processes. The primary centres of the vertebree make their appearance during the seventh or eighth week of embryonic existence, the lamella being somewhat in advance of that for the body. From the former are pro- duced the spinous, transverse, and articular processes, and the sides of the body ; they unite, to complete the arch, one year after birth, and with the body during the fifth year. The epiphyses, for the extremi- ties of the spinous and transverse processes, make their appearance at fifteen or sixteen, and become united between twenty and twenty- five. The epiphyses of the body are somewhat later in appearance, and are consolidated between the periods of twenty-five and thirty years of age. The ossific centres for the lateral masses of the atlas appear at the same time with those of the other vertebre ; they unite posteriorly at the end of the second year, by the intervention of the centre for the posterior arch. The one or two centres of the anterior arch appear during the first year, and become consolidated with the lateral pieces during the fifth or sixth year. The aais develops its lateral pieces at the same time with the rest of the vertebre ; they join posteriorly soon after birth, and with the body during the fourth or fifth year. The centres for the body and odontoid process appear during the sixth month, and are consolidated during the third year. The body of the axis is more largely developed at birth than that of the other ver- tebre. The costal segments of the vertebra prominens appear during the second month, and become united to the body at the fifth or sixth year. These processes sometimes remain permanently separate, and constitute a cervical rib. The transverse process of the first lumbar vertebra has sometimes a distinct centre, which may remain per- manently separate, in that case forming a lumbar rib. The ossification of the arches of the vertebree commences from above, and proceeds gradually downwards ; hence arrest of develop- ment gives rise to spina bifida, generally in the loins. Ossification of the bodies, on the contrary, commences from the centre, and proceeds c 18 SACRUM. from that point towards the extremities of the column ; hence im- perfection of the bodies occurs either in the upper or lower ver- tebree. * Attachment of muscles—To the atlas are attached ten pairs of muscles ; the longus colli, rectus anticus minor, rectus lateralis, rectus posticus minor, obliquus superior and inferior, splenius colli, levator anguli scapula, first interspinales, and first intertransversales. To the aais are attached twelve pairs, viz.: the longus colli, inter- transversales, obliquus inferior, rectus posticus major, supraspinalis, interspinales, semi-spinalis colli, multifidus spina, levator anguli sca- pulz, splenius colli, transversalis colli, and scalenus posticus. To the remaining vertebre collectively, thirty-three pairs ;—viz. pos- teriorly, the trapezius, latissimus dorsi, levator anguli scapulze, rhomboi- deus minor and major, serratus posticus superior and inferior, splenius, sacro-lumbalis, longissimus dorsi, spinalis dorsi, cervicalis ascendens, transyersalis colli, trachelo-mastoideus, complexus, semi-spinalis dorsi and colli, multifidus spine, supraspinalis, interspinales, intertransver- sales, levatores costarum ;—anteriorly, the rectus anticus major, longus colli, scalenus anticus and posticus, psoas magnus, psoas parvus, quad- ratus lumborum, diaphragm, obliquus internus and transversalis. Tue Sacrum is a triangular bone, situated at the lower extremity of the vertebral column, and formed by the consolidation of five false vertebra. It is divisible into an anterior and posterior surface, two lateral and a superior border, and an inferior extremity. The anterior surface is concave, and marked by four transverse lines, which indicate its original constitution of five separate pieces. At the extremities of these lines, on each side, are the four anterior sacral foramina, which diminish in size from above downwards, and transmit the anterior sacral nerves. The projection of the superior piece is the sacro-vertebral angle or promontory. The posterior surface is narrower than the anterior and convex. Upon the middle line is a rough crest formed by the rudiments of four spinous processes, the fifth remaining undeveloped and exposing the lower termination of the sacral canal. Immediately external to and parallel with the median crest, is a range of five small tubercles which represent the posterior tranverse processes of the true vertebree ; beyond these is a shallow groove in which the four posterior sacral foramina open, and farther externally, a range of five tubercles corresponding with the anterior or costal transverse processes of the lumbar vertebrae. The lowest pair of the posterior transverse tubercles bound on each’ side the termination of the sacral canal, and send, each, a process down- wards to articulate with the coccyx. The two descending processes are the sacral cornua. The posterior sacral foramina are smaller than the anterior, and transmit the posterior sacral nerves. Of the anterior transverse tubercles the first corresponds with the angle of the superior border of the bone ; the second is small, and enters into the formation — SACRUM. 19 of the sacro-iliac articula- tion ; the third is large, and gives attachment to the oblique sacro-iliac ligament ; the fourth and fifth are smaller, and serve for the attachment of the sacro-is- chiatic ligaments. The Ja- teral border of the sacrum presents superiorly a broad and ear-shaped (auricular) surface to articulate with the ilium ; and inferiorly a sharp-edge, to which the greater and lesser sacro-is- chiatic ligaments are at- tached. On the superior border, in the middle line, is an oval articular surface, which corresponds with the under part of the body of the last lumbar vertebra ; and on each side, a broad triangular surface which supports the lumbo-sacral nerve and psoas magnus muscle. Immediately be- hind the vertebral articular surface is the triangular entrance of the sacral canal; and on each side of this opening an articular process, which looks backwards and inwards, like the superior articular pro- cesses of the lumbar vertebrae. In front of each articular process is an intervertebral notch. The inferior extremity of the bone. presents a small oval surface which articulates with the coccyx ; and on each side a notch, which, with a corresponding notch in the upper border of the coccyx, forms the foramen for the transmission of the fifth sacral nerve. The sacrum presents some variety in respect of curvature, and of the number of pieces which enter into its structure. The curve is often very slight, and is situated only near the lower part of the bone ; while in other subjects it is considerable, and occurs at the middle of the sacrum. The sexual differences in the sacrum relate to its greater breadth, and the greater angle which it forms with the rest of the ver- tebral column in the female, rather than to any peculiarity in shape. It is sometimes composed of six pieces, more rarely of four, and occa- sionally the first and second pieces remain permanently separate. * The sacrum seen upon its anterior surface. 1, 1. The transverse lines marking the original constitution of the bone of four pieces. 2, 2: The ante- rior sacral foramina. 3. The promontory of the sacrum. 4. The ear-shaped surface which articulates with the ilium. 5. The sharp edge to which the sacro- ischiatic ligaments are attached. 6. The vertebral articular surface. 7. The broad triangular surface which supports the psoas muscle and lumbo-sacral nerve. 8. The articular process of the right side. 9. The inferior extremity, or apex of the sacrum. 10. One of the sacral cornua. 11. The notch which is converted into a foramen by the coccyx. 20 Coccyx. Development.—By twenty-one points of ossification ; five for each of the three first pieces, viz. one for the body, one for each lateral por- tion, and one for each lamina; and three for each of the two last, namely, one for the body, and one for each lateral portion. In the progress of growth, and after puberty, fourteen epiphysal centres are added, namely, two for the surfaces of each body, one for each auricu- lar surface, and one for the thin edge of each lateral border. Ossifica- tion begins in the bodies of the sacral pieces somewhat later than in those of the true vertebre ; the first three appearing during the eighth and ninth week, and the last two at about the middle of intra-uterine existence. Ossification of the lamelle takes place during the interval between the sixth and the ninth month. The epiphyses for the upper and under surface of the bodies are developed during the interval be- tween the fifteenth and eighteenth year; and for the auricular and marginal piece, after twenty. The two lower vertebral pieces, although the last to appear, are the first to be completed (between the fourth and fifth year), and to unite by their bodies. The union of the bodies takes place from below upwards, and finishes between the twenty- fifth and the thirtieth year, with the first two pieces. Articulations. — With four bones; the last lumbar vertebra, ossa innominata, and coccyx. Attachment of Muscles—To seven pairs ; in front the pyriformis, on the side the coccygeus, and behind the gluteus maximus, latissimus dorsi, longissimus dorsi, sacro-lumbalis, and multifidus spine. The Coccyx (xéxxv% cuckoo, from resembling a cuckoo’s beak) is composed of four small pieces, which form the caudal termination of the vertebral column. The superior piece is broad, and expands late- rally into two transverse processes ; it is surmounted by an oval arti- cular surface and two cornua, the former to articulate with the apex of the sacrum, and the latter with the sacral cornua. The lateral wings sometimes become connected with the sacrum, and convert the notches for the fifth pair of sacral nerves into foramina, The remaining three pieces diminish in size from above downwards. Development.—By four centres, one for each piece. Ossification commences in the first piece soon after birth ; in the second, between five and ten years; in the third, between ten and fifteen; and in the fourth between fifteen and twenty. The pieces unite at an earlier period than the bodies of the sacrum, the two first pieces first, then the third and fourth, and lastly the second and third. Between forty and sixty years, the coccyx becomes consolidated with the sacrum; this event taking place later in the female than in the male. Articulations.—W ith the sacrum. Attachment of Muscles.—To three pairs, and one single muscle : gluteus maximus, coccygeus, posterior fibres of the levator ani, and sphincter ani. OCCIPITAL BONE. 21 OF THE SKULL. The skull, or superior expansion of the vertebral column, is divisible into two parts,—the cranium and the face ; the former being adapted by its form, structure, and strength, to contain and protect the brain, and the latter the chief organs of sense. The Cranium is composed of eight separate bones ; viz. the Occipital, Two temporal, Two parietal, Sphenoid, Frontal, Ethmoid. OccipiraL Bonz.—This bone is situated at the posterior part and Fig. 11.* base of the cranium. It is trapezoid in figure, and divisible into two surfaces, four borders, and four angles. External Surface.—Crossing the middle of the bone transversely, from one lateral angle to the other, is a prominent ridge, the superior * The external surface of the occipital bone. 1. The superior curved line. 2. The external occipital protuberance. 3. The spine. 4, The inferior curved line. 5. The foramen magnum. 6. The condyle of the right side. 7. The ach condyloid fossa, in which the posterior condyloid foramen is found. 8. e anterior condyloid foramen, concealed by the margin of the condyle. 9. The transverse process; this process upon the internal surface of the bone forms the jugular eminence. 10. The notch in front of the jugular eminence which forms part of the jugular foramen. 11. The basilar process. 12, 12. The rough projections into which the odontoid ligaments are inserted. 22 OCCIPITAL BONE. curved line. In the middle of the ridge is a projection, called the ea- ternal occipital protuberance ; and descending from it a small vertical ridge, the spine. Above and below the superior curved line the sur- face is rough, for the attachment of muscles. About three-quarters of an inch below this line is another transverse ridge, the inferior curved line, and, beneath the latter, the foramen magnum. On each side of the foramen magnum, nearer to its anterior than its posterior segment, and encroaching somewhat upon the opening, is an oblong articular surface, the condyle, for articulation with the atlas. The condyles approach towards each other anteriorly, and their articular surfaces look downwards and outwards. Directly behind each condyle is an irregular fossa, and a small opening the posterior condyloid foramen, for the transmission of a vein to the lateral sinus. In front of the condyle is the anterior condyloid foramen, for the hypoglossal nerve ; and on the outer side of each condyle a projecting ridge, the transverse process, excavated in front by a notch which forms part of the jugular fora- men. In front of the foramen magnum is a thick square mass, the basilar process, and in the centre of the basilar process a small tubercle for the attachment of ‘the superior and middle constrictor muscles of the pharynx. Internal Surface.—Upon the internal surface is a crucial ridge, which divides the bone into four fossee ; the two superior or cerebral fossze lodging the posterior lobes of the cerebrum ; and the two in- ferior or cerebellar, the lateral lobes of the cerebellum. The superior arm of the crucial ridge is grooved for the superior longitudinal sinus, and gives attachment to the falx cerebri; the inferior arm is. sharp and prominent, for the attachment of the falx cerebelli, and slightly grooved, for the two occipital sinuses. The transverse ridge gives at- tachment to the tentorium cerebelli, and is deeply grooved, for the lateral sinuses. At the point of meeting of the four arms, is a pro- jection, the internal occipital protuberance, which corresponds with the similar process situated upon the external surface of the bone. The convergence of the four grooves forms a slightly depressed fossa, upon which rests the torcular Herophili. In the centre of the basilar por- tion of the bone is the foramen magnum, oblong in form, and larger behind than before, transmitting the spinal cord, spinal accessory nerves, and vertebral arteries. Upon the lateral margins of the fora- men magnum are two rough eminences, which give attachment to the odontoid ligaments, and immediately above these the openings of the anterior condyloid foramina. In front of the foramen magnum is the basilar process, grooved on its surface, for supporting the medulla oblongata, and along each lateral border, for the inferior petrosal si- nuses. On each side of the foramen magnum is a groove, for the termination of the lateral sinus ; a smooth surface, which forms part of the jugular fossa ; and a projecting process which divides the two, and is called the jugular eminence. Into the jugular fossa will be seen opening the posterior condyloid foramen. The superior borders are very much serrated, and assist in forming OCCIPITAL BONE. 23 Fig. 12.* the lambdoidal suture; the inferior are rough, but not serrated, and articulate with the mastoid portion of the temporal bone by means of the additamentum suture lambdoidalis. The jugular eminence and the side of the basilar process articulate with the petrous portion of the temporal bone, and the intermediate space, which is irregularly notched, forms the posterior boundary of the jugular foramen, or fora- men lacerum posterius. The angles of the occipital bone are the superior, inferior, and two lateral. The superior angle is received into the interval formed by the union of the posterior and superior angles of the parietal bones, and corresponds with that portion of the foetal head which is called the posterior fontanelle. The inferior angle is the articular extremity of the basilar process. The /ateral angles at each side project into that * The internal surface of the occipital bone. 1. The left cerebral fossa. 2. The left cerebellar fossa. 3. The groove for the posterior part of the superior longitudinal sinus. 4. The spine for the falx cerebelli, and groove for the occipital sinuses. 5. The groove for the left lateral sinus. 6. The internal occipital protuberance, the groove on which lodges the torcular Herophili. 7. The foramen magnum. 8. The basilar process, grooved for the medulla ob- longata. 9. The termination of the groove for the lateral sinus, bounded ex- ternally by the jugular eminence. 10. The jugular fossa; this fossa is com- pleted by the petrous portion of the temporal bone. 11. The superior border. 12. The inferior border. 13. The border which articulates with the petrous portion of the temporal bone, and which is grooved by the inferior petrosal sinus. 14. The anterior condyloid foramen. 24 PARIETAL BONE interval formed by the articulation of the posterior and inferior angle of the parietal with the mastoid portion of the temporal bone. _ Development.—By seven centres; four for the four parts of the ex- panded portion divided by the crucial ridge, one for each condyle, and one for the basilar process. Ossification commences in the expanded portion of the bone at a period anterior to the vertebre; at birth the four pieces are distinct; they are united at about the fifth or sixth year. After twenty the basilar process unites with the body of the sphenoid. Articulations.— With six bones; two parietal, two temporal, sphe- noid, and atlas. ( Attachment of Muscles.—To thirteen pairs; to the rough surface above the superior curved line, the occipito-frontalis; to the superior curved line, the trapezius and sterno-mastoid; to the rough space between the curved lines, complexus, and splenius capitis; to the space between the inferior curved line and the foramen magnum, the rectus posticus major and minor, and obliquus superior ; to the transverse pro- cess, the rectus lateralis ; and to the basilar process, the rectus anticus major and minor, and superior and middle constrictor muscles. Fig. 13.* PariETAL Bonz.—The parietal bone is situated at the side and vertex of the skull; it is quadrilateral in form, and divisible into an external and internal surface, four borders and four angles. The * The external surface of the left parietal bone. 1. The superior or sagittal border. 2. The inferior or squamous border. 3. The anterior or coronal bor- der. 4. The posterior or lambdoidal border. 5. The temporal ridge; the figure is situated immediately in front of the parietal eminence. 6. The parietal foramen, unusually large in the bone from which this figure was drawn. 7, The anterior inferior angle. 8. The posterior inferior angle. -PARIETAL BONE. 25 superior border is straights to articulate with its fellow of the opposite side. The inferior border is arched and thin, to articulate with the temporal bone. The anterior border is concave, and the posterior somewhat convex. External Surface.— Crossing the bone in a longitudinal direction from the anterior to the posterior border, is an arched line, the tem- poral ridge, to which the temporal fascia is attached. In the middle of this line, and nearly in the centre of the bone, is the projection called the parietal eminence, which marks the centre of ossification. Above the temporal ridge the surface is rough, and covered by the aponeurosis of the occipito-frontalis; below the ridge the bone is smooth (planum semicireulare) for the attachment of the fleshy fibres of the temporal muscle. Near the superior border of the bone, and at about one-third from its posterior extremity, is the parietal foramen, which transmits a vein to the superior longitudinal sinus. This fora- men is often absent. Fig. 14.* Da -5} Ss me) ~ fi jpn? wht ir i = | Internal Surface.—The internal table is smooth; it is marked by numerous furrows which lodge the ramifications of the arteria menin- gea media, and by digital fossee which correspond with the convolutions of the brain. Along the upper border is part of a shallow groove, * The internal surface of the left parietal bone. 1. The superior, or sagittal border. 2. The inferior, or squamous border. 3. The anterior, or coronal border. 4. The posterior, or lambdoidal border. 5. Part of the groove for the superior longitudinal sinus. 6. The internal termination of the parietal fora- men. 7. The anterior inferior angle of the bone, on which is seen the groove for the trunk of the arteria meningea media. 8. The posterior inferior angle, upon which is seen a portion of the groove for the lateral sinus. 26 FRONTAL BONE. completed by the opposite parietal bone, which serves to contain the superior longitudinal sinus. Some slight pits are also observable near this groove, which lodge the glandulz Pacchioni. ‘The anterior inferior angle is thin and lengthened, and articulates with the greater wing of the sphenoid bone. Upon its inner surface it is deeply channelled by a groove for the trunk of the arteria menin- gea media. This groove is frequently converted into acanal. The posterior inferior angle is thick, and presents a broad and shallow groove for the lateral sinus. Development.—By a single centre. Ossification commences at the parietal eminence at the same time with the bodies of the vertebra. Articulations.—W ith five bones; with the opposite parietal bone, the occipital, frontal, temporal, and sphenoid. Attachment of Muscles.—To one only,—the temporal,. The occi- pito-frontalis glides over its upper surface. FrontTAL Bone.—The frontal bone bears some resemblance in form to the under valve of a scallop shell. It is situated at the anterior part of the cranium, forming the forehead, and assists in the construc- tion of the roof of the orbits and nose. Hence it is divisible into a superior or frontal portion, and an inferior or orbito-nasal portion. Each of these portions presents for examination an external and inter- nal surface, borders, and processes. External Surface.—At about the middle of each lateral half of the frontal portion is a projection, the frontal eminence. Below these points are the superciliary ridges, large towards th@ inner termination, and becoming gradually smaller as they arch outwards: they support the eyebrows. Beneath the superciliary ridges are the sharp and prominent arches which form the upper margin of the orbits, the supra-orbital ridges. Externally the supra-orbital ridge terminates in the eaternal angular process, and internally in the internal angular process; at the inner third of this ridge is a notch, sometimes converted into a fo- ramen, the supra-orbital notch, which gives passage to the supra-orbi- tal artery, veins, and nerve. Between the two superciliary ridges is a rough projection, the nasal tuberosity ; this portion of the bone denotes by its prominence the situation of the frontal sinuses. Extending upwards and backwards from the external angular process is a sharp ridge, the commencement of the temporal ridge, and beneath this a depressed surface that forms part of the temporal fossa. r The orbito-nasal portion of the bone consists of two thin processes, the orbital plates, which form the roof of the orbits, and of an inter- vening notch which lodges the ethmoid bone, and is called the ethmoidal © fissure. The edges of the ethmoidal fissure are hollowed into cavities, which, by their union with the ethmoid bone, complete the ethmoidal - cells; and, crossing these edges transversely, are two small grooves, sometimes canals, which open into the orbit by the anterior and posterior ethmoidal foramina. At the anterior termination of these edges are the irregular openings which lead into the frontal sinuses; and be- FRONTAL BONE, Q7 tween the two internal angular processes, is a rough excavation which receives the nasal bones, and a projecting process, the nasal spine. Upon each orbital plate, immediately beneath the external angular process, is a shallow depression which lodges the lachrymal gland ; Fig. 15.* and beneath the internal angular process a small pit, sometimes a tubercle to which the cartilaginous pulley of the superior oblique muscle is attached. Internal Surface.— Along the middle line of this surface is a grooved ridge, the edges of the ridge giving attachment to the falx cerebri and the groove lodging the superior longitudinal sinus. At the commencement of the ridge is an opening, sometimes completed by the ethmoid bone, the foramen cecum. This opening lodges a process of the dura mater, and occasionally gives passage to a small vein which communicates with the nasal veins. On each side of the vertical ridge are some slight depressions which lodge the glandule Pacchioni, and on the orbital plates a number of irregular pits called digital fosse, * * The external surface of the frontal bone. 1. The situation of the frontal eminence of the right side. 2. The superciliary ridge. 3. The supra-orbital ridge. 4. The external angular process. 5. The internal angular process. 6. The supra-orbital notch for the transmission of the supra-orbital nerve and artery ; in the figure it is almost converted into a foramen by a small spiculum of bone. 7. The nasal tuberosity; the swelling around this point denotes the situation of the frontal sinuses. 8. The temporal ridge commencing from the external angular process (4). The depression in which the figure 8 is situ- ated is a part of the temporal fossa. 9. The nasal spine. 28 FRONTAL BONE. which correspond with the convolutions of the anterior lobes of the cerebrum. The superior border is thick and strongly serrated, bevel- led at the expense of the internal table in the middle, where it rests Fig. 16.* upon the junction of the two parietal, and at the expense of the exter- nal table, on each side, where it receives the’ lateral pressure of those bones. The inferior border is thin, irregular, and squamous, and articulates with the sphenoid bone. Development.—By two centres, one for each lateral half. Ossifica- tion begins in the orbital arches, somewhat before the vertebrae. The two pieces are separate at birth, and unite by suture during the first year, the suture sometimes remaining permanent through life. The frontal sinuses make their appearance during the first year, and increase in size until old age. * The internal surface of the frontal bone; the bone is raised in such a man- ner as to show the orbito-nasal portion. 1. The grooved ridge for the lodg- ment of the superior longitudinal sinus and attachment of the falx. 2. The foramen ceecum. 3. The superior or coronal border of the bone; the figure is situated near that part which is bevelled at the expense of the internal table. 4. The inferior border of the bone. 5. The orbital plate of the left side. 6. The cellular border of the ethmoidal fissure. The foramen ceecum (2) is seen through the ethmoidal fissure. 7. The anterior and posterior ethmoidal fora- mina; the anterior is seen leading into its canal. 8. The nasal spine. 9. The depression within the external angular process (12) for the lachrymal gland. 10. The depression for the pulley of the superior oblique muscle of the eye ; immediately to the left of this number is the supra-orbital notch, and to its right the internal angular process. 11. The opening leading into the frontal sinuses. 12, The same parts are seen upon the opposite side of the figure. TEMPORAL BONE. 29 Articulations.—With twelve bones; the two parietal, the sphenoid, ethmoid, two nasal, two superior maxillary, two lachrymal, and two malar. Attachment of muscles, —'To two pairs; corrugator supercilii, and temporal. TemPorAL Bonz.—The temporal bone is situated at the side and base of the skull, and is divisible into a squamous, mastoid, and petrous portion. The Squamous portion, forming the anterior part of the bone, is thin, translucent, and contains no diploé. Upon its external surface it is smooth, to give attachment to the fleshy fibres of the temporal muscle, and has projecting from it an arched and length- Fig. 17.* ECG THs he ened process, the zygoma. Near the commencement of the zygoma upon its lower border, is a projection called the tubercle, to which is attached the external lateral ligament of the lower jaw, and * The external surface of the temporal bone of the left side. 1. The squa- mous portion. 2. The mastoid portion. 3. The extremity of the petrous por- tion. 4. The zygoma. 5. Indicates the tubercle of the zygoma, and at the same time its anterior root turning inwards to form the eminentia articularis. 6. The superior root of the zygoma, forming the posterior part of the temporal ridge. 7. The middle root of the zygoma terminating abruptly at the glenoid fissure. 8. The mastoid foramen. 9. The meatus auditorius externus, sur- rounded by the processus auditorius. 10. The digastric fossa, situated imme- diately to the inner side of (2) the mastoid process. 11. The styloid process. 12. The vaginal process. 13. The glenoid or Glaserian fissure; the leading line from this number crosses the rough posterior portion of the glenoid fossa. 14. The opening and part of the groove for the Eustachian tube. 30 TEMPORAL BONE. continued horizontally inwards from the tubercle a rounded emi- ‘nence, the eminentia articularis. The process of bone which is continued from the tubercle of the zygoma into the eminentia articu- laris is the inferior root of the zygoma. The superior root is con- tinued upwards from the upper border of the zygoma, and forms the posterior part of the temporal ridge, serving by its projection to mark the division of the squamous from the mastoid portion of the bone ; and the middle root is continued directly backwards, and terminates abruptly at a narrow fissure, the fissura Glaseri. The internal sur- Jace of the squamous portion is marked by several shallow fosse, which correspond with the convolutions of the cerebrum, and by a furrow for the posterior branch of the arteria meningea media. The superior, or squamous border, is very thin, and bevelled at the expense of the inner surface, so as to overlap the lower and arched border of the parietal bone. The inferior border is thick and dentated to arti- culate with the spinous process of the sphenoid bone. The Mastoid portion forms the posterior part of the bone ; it is thick, and hollowed between its tables into a loose and cellular diploé. Upon its eaternal surface it is rough for the attachment of muscles, and contrasts strongly with the smooth and polished-like surface of the squamous portion ; every part of this surface is pierced by small fora- mina, which give passage to minute arteries and veins ; one of these openings, oblique in its direction, of large size, and situated near the posterior border of the bone, the mastoid foramen, transmits a vein to the lateral sinus. This foramen is not unfrequently situated in the occipital bone. The inferior part of this portion is round and ex- panded, the mastoid process, and excavated in its interior into . numerous cells, which form a part of the organ of hearing. In front of the mastoid process, and between the superior and middle roots of the zygoma, is the large oval opening of the meatus auditorius eaternus, surrounded by a rough lip, the processus auditorius. Directly to the inner side, and partly concealed by the mastoid process, is a deep groove, the digastric fossa ; and a little more internally the occipital groove, which lodges the occipital artery. Upon its internal surface the mastoid portion presents a broad and shallow groove (/ossa sigmoidea) for the lateral sinus, and terminating in this groove the internal opening of the mastoid foramen. The superior border of the mastoid portion is dentated ; and its posterior border thick and less serrated for articulation with the inferior border of the occipital bone. The meatus auditorius eaternus is a slightly curved canal, somewhat more than half an inch in length, longer along its lower than its upper wall, and directed obliquely inwards and forwards. The canal is narrower at the middle than at each extremity, is broadest in its horizontal diameter, and terminates upon the outer wall of the tympa- num by an abrupt oval border. Within the margin of this border is a groove for the insertion of the membrana tympani. The Petrous portion of the temporal bone is named from its extreme TEMPORAL BONE. 31 hardness and density. It is a three-sided pyramid, projecting hori- zontally forwards into the base of the skull, the base being applied against the internal surface of the squamous and mastoid portions, and the apex being received into the triangular interval between the spi- nous process of the sphenoid and the basilar process of the occipital bone. For convenience of description it is diyisible into three sur- faces—anterior, posterior, and basilar; and three borders—superior, anterior, and posterior. Surfaces.— The anterior surface, forming the posterior boundary of the middle fossa of the interior of the base of the skull, presents for examination from base to apex, first, an eminence caused by the pro- jection of the perpendicular semicircular canal ; next, a groove lead- ing to an irregular oblique opening, the hiatus Fallopii, for the transmission of the pe- trosal branch of the Vidian nerve ; thirdly, another and _ smaller oblique foramen, imme- diately beneath the pre- ceding, for the passage of the nervus petrosus superficialis minor, a branch of Jacobson’s nerve; and lastly, a large foramen near the apex of the bone, the termination of the caro- tid canal. The posterior surface forms the front boun- dary of the posterior fossa of the base of the skull; near its middle is the oblique entranee * The left temporal bone, seen from within. 1.The squamous portion. 2. The mastoid portion. The number is placed immediately above the inner opening of the mastoid foramen. 3. The petrous portion. 4. The groove for the posterior branch of the arteria meningea media. 5. The bevelled edge of the squamous border of the bone. 6. Thezygoma. 7. The digastric fossa im- mediately internal to the mastoid process. 8. ‘The occipital groove. 9. The groove for the lateral sinus. 10. The elevation upon the anterior surface of the petrous bone marking the situation of the perpendicular semicircular canal. 11. The opening of termimation of the carotid canal. 12. The meatus audito- rius internus, 13. A dotted line leads upwards from this number to the nar- row fissure which lodges a process of the dura mater. Another line leads downwards to the — edge which conceals the opening of the aqueeductus cochleze, while the number itself is situated on the bony lamina which overlies the opening of the aqueeductus vestibuli. 14. The styloid process. 15. The stylo-mastoid foramen. 16. The carotid foramen. 17. The jugular process. The deep excavation to the left of this process forms part of the jugular fossa, and that to the right is the groove for the eighth pair of nerves. 18. Thenotch for the fifth nerve upon the upper border of the petrous bone, near to its apex. 19. The extremity of the aekiS bone which gives origin to the levator palati and tensor tympani muscles. 32 ' (TEMPORAL BONE. of the meatus auditorius internus. Above the meatus auditorius in- ternus is a small oblique fissure, and a minute foramen ; the former lodges a process of the dura mater, and the foramen gives passage to a small vein. Further outwards, towards the mastoid portion of the bone, is a small slit, almost hidden by a thin plate of bone ; this is the aqueductus vestibuli, and transmits a small artery and vein of the ves- tibule and a process of dura mater. Below the meatus, and partly concealed by the margin of the posterior border of the bone, is the aqueductus cochlee, through which passes a vein from the cochlea to the internal jugular vein, and a process of dura mater. The meatus auditorius internus is about one-third of an inch in ’ depth, and pursues a slightly oblique course in relation to the petrous portion of the temporal bone, but a course directly outwards in relation to the cranium. At the bottom of the meatus, and upon its anterior aspect, is a reniform fossa, the concave border of which is directed towards the entrance of the meatus. The reniform fossa is divided into an upper and lower compartment by a sharp ridge, which is prolonged for some distance upon the anterior wall of the meatus and sometimes as far as its aperture ; in either case it marks the situation of the two nerves, facial and auditory, which constitute the seventh pair, and enter the meatus. Along the convexity of the reniform fossa, and arranged in a curved line from above downwards, are four of five openings, the two upper ones being the largest, and occupying the superior compartment of the reniform fossa, and the two or three inferior ones, smaller than the upper, the inferior com- partment. Behind the latter, at the distance of a line and a half, and on the posterior wall of the meatus is a cluster of three or four oblique openings, two of which are minute. The inferior and larger com- partment of the reniform fossa presents a well-magked spiral groove, which commences on the convex border of the fossa, immediately below the line of openings above described, and, sweeping round the con- vexity of the inferior compartment, and becoming deeper as it proceeds, terminates by a small round aperture in the centre of the spire. The uppermost of the openings of the reniform fossa is the aperture of the aquzeductus Fallopii and gives passage to the facial nerve. The rest are cul de sacs, pierced at the bottom by a number of minute foramina for the passage of filaments of the vestibular nerve, while the cluster of three openings on the posterior wall of the meatus are intended for single filaments of the same nerve. The spiral groove corresponds with the base of the cochlea, and being pierced by a number of minute foramina for filaments of the cochlear nerve, is named tractus spiralis foraminulentus. The opening in the centre of the spiral im- pression leads into a canal which occupies the central axis of the modiolus, and is thence called tubulus centralis modioli. The basilar surface is rough and irregular, and enters into the formation of the under surface of the base of the skull. Projecting downwards, near its middle, is a long sharp spine, the styloid process, occasionally connected with the bone only by cartilage and lost during TEMPORAL BONE. 33 maceration, particularly in the young subject. At the base of this process is a rough sheath-like ridge, into which the styloid process appears implanted, the vaginal process. In front of the vaginal pro- cess is a broad triangular depression, the glenoid fossa, bounded in front by the eminentia articularis, behind by the vaginal process, and externally by the rough lip of the processus auditorius. Fig. 19.* _ This fossa is divided transversely by the glenoid fissure (fissura Glaseri) which lodges the extremity of the processus gracilis of the malleus, and transmits the laxator tympani muscle, chorda tympani nerve, and anterior tympanic artery. The surface of the fossa in front of this fissure is smooth, to articulate with the condyle of the lower jaw ; and that behind the fissure is rough, for the reception of a part of the parotid gland. At the extremity of the inner angle of the glenoid fossa is the foramen of the Hustachian tube; and separated from it by a thin lamella of bone, called processus cochleariformis, a small canal for the transmission of the tensor tympani muscle. Directly be- hind, and at the root of the styloid process, is the stylo-mastoid fora- men, the opening of exit to the facial nerve, and of entrance to the stylo-mastoid artery. Nearer to the apex of the bone is a large oval * A. The reniform fossa of the meatus auditorius internus; right temporal bone. 1. The ridge dividing the reniform fossa into two compartments. 2. The opening of the aquzeductus Fallopii. The openings following that of the uzeductus Fallopii in a curved direction require no reference. 3. The cluster of three or four oblique openings on the posterior wall of the meatus. 4. The spirally-grooved base of the cochlea. B. A section of the temporal bone, right side, shewing the curved direction of the meatus auditorius externus. 1. The edge of the processus auditorius. 2. The groove into which the membrana tympani is inserted. The obliquity of the line from 2 to 3 indicates the oblique termination of the meatus, and the consequent oblique direction of the membrana tympani. 4, 4. The cavity of the tympanum. 5. The opening of the Eustachian tube. 6. Part of the aquee- ductus Fallopii. 7. Part of the carotid canal. C. The annulus membrane tympani or tympanic bone of the fetal skull ; right side. D 34 TEMPORAL BONE. opening, the carotid foramen, the commencement of the carotid canal, which lodges the internal carotid artery and the carotid plexus. And between the stylo-mastoid and carotid foramen, in the posterior border, is an irregular excavation forming part of the jugular fossa for the commencement of the internal jugular vein. The proportion of the jugular fossa formed by the petrous portion of the temporal bone is very different in different bones ; but in all, the fossa presents a vertical ridge to its inner side, which cuts off a small portion from the rest. The upper part of this ridge forms a spinous projection, which is called the jugular process, the groove to the inner side of the ridge lodges the eighth pair of nerves, and the lower part of the ridge is the septum of division between the jugular fossa and the carotid foramen. Upon this portion of the ridge near the posterior margin of the carotid foramen is a small opening leading into a canal, which transmits the tympanic branch of the glossopharyngeal nerve (Jacobson’s nerve). Between the jugular fossa and the stylo-mastoid foramen is another small opening leading into the canal for the passage of the tympanic branch of the pneumogastric nerve. Borders.—The superior border is sharp, and gives attachment to the tentorium cerebelli. It is grooved for the superior petrosal sinus, and near its extremity is marked by a smooth notch upon which reclines the fifth nerve. The anterior border is grooved for the Eustachian tube, and forms the posterior boundary of the foramen lacerum basis cranii ; by its sharp extremity it gives attachment to the tensor tympani and levator palati muscles. The posterior border is grooved for the inferior petro- sal sinus, and excavated for the jugular fossa; it forms the anterior boundary of the foramen lacerum posterius. Development.—By five centres ; one for the squamous portion, one for the mastoid process, one for the petrous portion, one for the audi- tory process, which in the foetus is a mere bony ring, incomplete supe- riorly, and serving for the attachment of the membrana tympani, annulus membrane tympani ; and one for the styloid process. Ossifi- cation occurs in these pieces in the following order: in the squamous portion immediately after the vertebrae, then in the petrous, tympanic, mastoid, and styloid. The tympanic ring is united by its extremities to the squamous portion during the last month of intrauterine life ; the squamous, petrous and mastoid portions are consolidated during the first year: and the styloid some years after birth. It not unfrequently happens that the latter.remains permanently separate, or is prolonged by a series of pieces to the os hyoides, and so completes the hyoid arch. The subsequent changes in the bone are the increase of size of the glenoid fossa, the growth of the meatus auditorius externus, the level- ling of the surfaces of the petrous portion and the development of mastoid cells. Traces of the union of the petrous with the squamous portion of the bone are usually perceptible in the adult. Articulations.—With five bones; occipital, parietal, sphenoid, in- ferior maxillary and malar. SPHENOID BONE. 35 Attachment of Muscles——To fourteen; by the squamous portion, to the temporal ; by the zygoma, to the masseter; by the mastoid por- tion, to the occipito-frontalis, splenius capitis, sterno-mastoid, trachelo- mastoid, digastricus and retrahens aurem; by the styloid process, to the stylo-pharyngeus, stylo-hyoideus, stylo-glossus, and two ligaments, the stylo-hyoid and stylo-maxillary; and by the petrous portion, to the levator palati, tensor tympani, and stapedius. SpHENow Bonz.—The sphenoid (c¢%», a wedge) is an irregular bone situated at the base of the skull, wedged between the other bones of the cranium, and entering into the formation both of the cranium and face. It bears some resemblance in form to a bat with its wings extended, and is divisible into body, wings, and processes. The body forms the central mass of the bone, from which the wings and processes are projected. From the upper and anterior part of the body extend on each side two small triangular plates,—the lesser wings; from either side and expanding laterally are the greater wings; pro- ceeding backwards from the base of the greater wings, the spinous processes, and downwards, the pterygoid processes. The body presents for examination a superior or cerebral surface, an antero-inferior surface, and a posterior surface. Superior Surface.—At the anterior extremity of this surface is a small projecting plate, the ethmoidal spine, and spreading out on either side the lesser wings. Behind the ethmoidal spine in the middle line is a rounded elevation, the olivary process, which supports the commissure of the optic nerves, and on either side of the posterior margin of this process is a tubercle, the middle clinoid process. Pass- ing outwards and forwards from the olivary process, are the optic foramina, which transmit the optic nerves and ophthalmic arteries. Behind the optic foramina are two sharp tubercles, the anterior clinoid processes, which are the inner terminations of the lesser wings. Be- neath these processes, on the sides of the olivary process, are two depressions* for the last turn of the internal carotid arteries. Behind the olivary process is the sella turcica (ephippium), the deep fossa which lodges the pituitary gland and circular sinus ; behind and some- what overhanging the sella turcica, is a broad rough plate (dorsum ephippii), bounded at each angle by a tubercle, the posterior clinoid processes ; and behind this plate an inclining surface (clivus Blumen- bachii), which is continuous with the basilar process of the occipital bone. On either side of the sella turcica is a broad groove (carotid) which lodges the internal carotid artery, the cavernous sinus, and the orbital nerves. Immediately external to this groove, at the junction of the greater wings with the body, are four foramina: the first isa broad interval, the sphenoidal fissure, which separates the greater and lesser wings, and transmits the third, fourth, the three branches of the * These degerasaet are occasionally, as in a skull before me, converted into foramina by the extension of a short bony pillar from the middle to the anterior clinoid process, . 36 SPHENOID BONE. © ophthalmic division of the fifth and the sixth nerves, and the ophthal- mic vein. Behind and beneath this fissure is the foramen rotundum for the superior maxillary nerve ; and still farther back, in the base of the spinous process, the foramen ovale for the inferior maxillary nerve, Fig, 20.* arteria meningea parva, and nervus petrosus superficialis minor. Be- hind the foramen ovale, near the apex of the spinous process, is the foramen spinosum for the arteria meningea media. Upon the wntero-inferior surface of the sphenoid is a long flattened - spine or crest, the superior part of which, crista sphenoidalis, articulates with the central lamella of the ethmoid, while the inferior part longer and sharper, the rostrum sphenoidale, is intended to be inserted into the sheath formed by the upper border of the vomer. On either side of the crista sphenoidalis is an irregular opening leading into the * The superior or cerebral surface of the sphenoid bone. 1. The processus olivaris. 2, The ethmoidal spine. 3. The lesser wing of the left side. 4. The cerebral surface of the greater wing of the same side. 5, The spinous process. 6. The extremity of the pterygoid process of the same side, projecting downwards from the under surface of the body of the bone. 7. The foramen opticum. 8. The anterior clinoid process. 9. The groove by the side of the sella turcica; for lodging the internal carotid artery, cavernous plexus, ca- vernus sinus, and orbital nerves. 10. The sella turcica; the two tubercles in front of the figure are the middle clinoid processes. 11. The posterior boundary of the sella turcica; its projecting angles are the posterior clinoid processes. 12. The basilar portion of the bone. 13. Part of the sphenoidal fissure. 14, The foramen rotundum. 15. Theforamen ovale. 16. The foramen spinosum. 17. The angular interval which receives the apex of the petrous portion of the temporal bone. The posterior extremity of the Vidian canal terminates at this angle. 18. The spine of the spinous process; it affords attachment to the in- ternal lateral ligament of the lower jaw. 19. The border of the greater wing and spinous process, which articulates with the anterior part of the squamous portion of the temporal bone. 20. The internal border of the spinous process, which assists in the formation of the foramen lacerum basis cranii. 21. That portion of the greater ala which articulates with the anterior inferior angle of the parietal bone. 22. The portion of the greater ala which articulates with the orbital process of the frontal bone. SPHENOID BONE. 37 sphenoidal cells. The sphenoidal cells, which are absent in the young subject, are divided by a median septum which is continuous with the crista, and are partially closed by two thin plates of bone (frequently broken away), the sphenoidal spongy bones. On each side of the sphe- noidal cells are the outlets of the optic foramina, sphenoidal fissures, and foramina rotunda, the lesser and greater wings; and below, the pterygoid processes. Upon the under surface of the body are two thin plates of bone (processus vaginales) proceeding from the base of the pterygoid process at each side and intended for articulation with the borders of the vomer. On each of these plates, close to the root of Fig. 21.* the pterygoid process, is a groove (sometimes a complete canal) con- verted into a canal by the palate bone, the pterygo-palatine canal for the pterygo-palatine artery ; and traversing the roots of the pterygoid processes at their union with the body of the bone are the two ptery- goid or Vidian canals which give passage to the Vidian nerve and artery at each side. The posterior surface is flat and rough, and articulates with the basilar process of the occipital bone. In the adult, this union is usually completed by bone; from which circumstance the sphenoid, in con- junction with the occipital, is described by Soemmering and Meckel as a single bone, under the name of spheno-occipital. The posterior * The antero-inferior view of the sphenoid bone. 1. The ethmoid spine. 2. The rostrum. 3. The sphenoidal spongy bone, partly closing the left open- ing of the sphenoidal cells. 4. The lesser wing. 5. The foramen opticum piercing the base of the lesser wing. 6. The sphenoidal fissure. 7. The fora- men rotundum. 8. The orbital surface of the greater wing. 9. Its temporal surface. 10. The pterygoid ridge. 11. The pterygo-palatine canal. 12. The foramen of entrance to the Vidian canal. 13. The internal en plate. 14. The hamular process. 15. The external pterygoid plate. 16 The fora- men spinosum. 17. The foramen ovale. 18. The extremity of the spinous process of the sphenoid, 38 SPHENOID BONE. surface is continuous on each side with the spinous process, and at the angle of union is the termination of the Vidian canal. The lesser wings (processes of Ingrassias) are thin and triangular, the base being attached to the upper and anterior part of the body of the sphenoid, and the apex extended outwards, and terminating in an acute point. The anterior border is irregularly serrated, the posterior being free and rounded and received into the fissure of Sylvius of the cerebrum. ‘The inner extremity of this border is the anterior clinoid process, which is supported by a short pillar of bone, giving attach- ment to a part of the common tendon of the muscles of the orbit. The lesser wing forms the posterior part of the roof of the orbit, and its base is traversed by the optic foramen. The greater wings present three surfaces; a superior or cerebral, which forms part of the middle fossa of the base of the skull, an ante- rior surface which assists in forming the outer wall of the orbit, and an external surface divided into two parts by the pterygoid ridge. The superior part of the external surface enters into the formation of the temporal fossa, and the inferior portion forms part of the zygomatic fossa. The pterygoid ridge, dividing the two, gives attachment to the upper origin of the pterygoideus externus muscle. The spinous processes project backwards at each side from the base of the greater wings of the sphenoid, and are received into the angu- lar intervals between the squamous and petrous portions of the tem- poral bones. Piercing the base of each process is a large oval opening, the foramen ovale; nearer its apex a smaller opening, the foramen spinosum ; and extending downwards from the apex a short~-spine, which gives attachment to the internal lateral ligament of the lower jaw and to the laxator tympani muscle. The external border of the spinous process is rough, to articulate with the lower border of the squamous portion of the temporal bone; the internal forms the ante- rior boundary of the foramen lacerum basis cranii, and is somewhat grooved for the reception of the Eustachian tube. The pterygoid processes descend perpendicularly from the base of the greater wings, and form in the articulated skull the lateral boun- daries of the posterior nares. Each process consists of an external and internal plate, and an anterior surface. The external plate is broad and thin, giving attachment, by its external surface, to the ex- ternal pterygoid muscle, and by its internal surface to the internal pterygoid. This plate is sometimes pierced by a foramen, which is not unfrequently formed by a process of communication passing between it and the spinous process. The internal pterygoid plate is long and narrow, and terminated at its extremity by a curved hook, the hamu- lar process, around which plays the tendon of the tensor palati muscle. At the base of the internal pterygoid plate is a small oblong depres- sion, the scaphoid fossa, from which arises the circumflexus or tensor palati muscle. The interval between the two pterygoid plates is the plerygoid fossa ; and the two plates are separated inferiorly by an an- gular notch (palatine) which receives the tuberosity, or pterygoid ETHMOID BONE. 39 process, of the palate bone. The anterior surface of the pterygoid process is broad near its base, and supports Meckel’s ganglion. The base of the process is pierced by the Vidian canal. Development.—By twelve centres ; four for the body, viz. two for its anterior (spheno-orbital), and two for its posterior part (spheno- temporal) ; four for the four wings; two for the internal pterygoid plates, and two for the sphenoidal spongy bones. Ossification com- mences in the various pieces of the sphenoid in the following order :— greater ale, at about the same time with the other bones of the cranium ; lesser ale, posterior body, at the end of the second month ; anterior body at the end of the third ; internal pterygoid plate, spongy bones, between the period of birth and the second year. Osseous union occurs first between the centres for the posterior body, and at about the same time between each centre of the anterior body and its corresponding (lesser) ala; the third union takes place between the internal, pterygoid plate and the greater ala ; the fourth between the two centres of the anterior body, and at the same time between the anterior and posterior body. This is the state of union at birth, the bone consisting of five centres, one being the body and lesser ale ; one on each side, the great ala and internal pterygoid plate ; and the remaining two the sphenoidal spongy bones. The greater alz unite with the body during the first year ; the spongy bones after puberty ; and the body of the sphenoid with the basilar process of the occipital between eighteen and twenty-five. Articulations.—With twelve bones ; ali the bones of the head and five of the face, viz. the two malar, two palate, and the vomer. Attachment of Muscles—To twelve pairs ; temporal, external ptery- goid, internal pterygoid, superior constrictor, tensor palati, laxator tympani, levator palpebra, obliquus superior, superior rectus, internal rectus, inferior rectus, and external rectus. Erxumow Bonse.—The ethmoid (40s, a sieve) is a square-shaped cellular bone, situated between the two orbits, at the root of the nose, and perforated upon its upper surface by a number of small openings, from which peculiarity it has received its name. It consists of a perpendicular lamella and two lateral masses. The perpendicular lamella is a thin central plate, which articulates with the vomer and cartilage of the septum, and assists in forming the septum of the nose. It is surmounted superiorly by a thick and strong process, the crista galli, which projects into the cavity of the skull, and gives attachment to the falx cerebri. From the base of. the anterior border of this process there project forwards two small plates, alar processes, which are received into corresponding depres- sions in the frontal bone, and often complete posteriorly the foramen cecum. On each side of the crista galli, upon the upper surface of the bone, is a thin and grooved plate perforated by a number of small openings, the eribriform lamella, which supports the bulb of the olfactory nerve, and gives passage to its filaments, and to the nasal 40 ETHMOID BONE. branch of the ophthalmic nerve. In the groove of this lamella the foramina pierce the bone complete- ly, but at either side they are the apertures of canals, which run for some distance in the substance of the central lamella, inner wall of the lateral mass and spongy bones. The opening for the nasal nerve is a narrow slit.in the anterior part of of the cribriform lamella, close to the crista galli. The cribriform . lamella serves to connect the la- teral masses with the perpendicu- lar plate. The lateral masses (labyrinthi) are divisible into an internal and external surface, and four borders, superior, inferior, anterior, and posterior. The internal surface is rough and slightly convex, and forms the external boundary of the upper part of the nasal fosse. Towards the posterior border of this surface is a narrow horizontal fissure, the superior meatus of the nose, the upper margin of which is thin, and somewhat curled inwards ; hence it is named the superior turbinated bone (concha superior). Below the meatus is the convex surface of another thin plate, which is curled outwards, and forms the lower border of the mass, the middle turbinated bone (concha media). The eaternal surface is quadrilateral and smooth, hence it is named os planum, and, from its thinness, lamina papyracea ; it enters into the formation of the inner wall of the orbit. The superior border is irregular and cellular, the cells being com- pleted by the edges of the ethmoidal fissure of the frontal bone. This border is crossed by two grooves, sometimes complete canals, opening into the orbit by the anterior and posterior ethmoidal foramina. The inferior border is formed internally by the lower border of the middle turbinated bone, and externally by a concave irregular fossa, the upper boundary of the middle meatus. The anterior border presents a number of incomplete cells, which are closed by the superior maxillary * The ethmoid bone seen from above and behind. 1. The central lamella. 2, 2. The lateral masses; the numbers are placed on the posterior border of the lateral mass at each side. 3. The crista galli process. 4. The cribriform plate of the left side, pierced by the cribriform foramina. 5. The hollow space immediately above and to the left of this number is the superior meatus. 6. The superior turbinated bone. 7. The middle turbinated bone; the numbers 5, 6, 7, are situated upon the internal surface of the left lateral mass, near its osterior part. The interval between these parts is the superior meatus. 8. e external surface of the lateral mass, or os planum. 9. The superior or frontal border of the lateral mass, grooved by the anterior and posterior eth- moidal canals. 10. Refers to the concavity of the middle turbinated bone, which is the upper boundary of the middle meatus. SUPERIOR MAXILLARY BONES. 7 4] and lachrymal bone ; and the posterior border is irregularly cellular, to articulate with the sphenoid and palate bones. The lateral masses are composed of cells, which are divided by a thin partition into anterior and posterior ethmoidal cells. The anterior, the most numerous, communicate with the frontal sinuses, and open by means of an irregular and incomplete tubular canal, the infundibulum, into the middle meatus. The posterior cells, fewer in number, open into the superior meatus. Development.—By three centres ; one for each lateral mass, and one for the perpendicular lamella. Ossification commences in the lateral masses at about the beginning of the fifth month, appearing first in the os planum and then in the spongy bones. During the latter half of the first year after birth, the central lamella and lamina cribrosa begin to ossify, and are united to the lateral masses by the beginning of the second. The cells of the ethmoid are developed in the course of the fourth and fifth year. Articulations.—W ith thirteen bones ; two re cranium, — - tiie. frontal and sphenoid ; the rest of the face, viz./the nasal, superior * maxillary, lachrymal, palate, the inferior turbinated, and the vomer. No muscles are attached to this bone. BONES OF THE FACE. 3 The face is composed of fourteen bones ; viz. the Two nasal, Two palate, Two superior maxillary, Two inferior turbinated, Two lachrymal, Vomer. Two malar, Inferior maxillary. Nasa Bonrs.—The nasal (fig. 28) are two small quadrangular bones, forming by their union the bridge and base of the nose. Upon the upper surface they are convex, and pierced by a foramen for a small artery; on the under surface they are somewhat concave, and marked by a groove, which lodges the nasal branch of the ophthalmic nerve. The superior border is narrow and thick, the inferior broad, thin, and irregular. ment.—By a single centre for each bone, the first ossific de- position making its appearance at the same time as in the vertebre. Articulations—With four bones; frontal, ethmoidal, nasal, and superior maxillary. Attachment of Muscles. —It has in relation with it the pyramidalis nasi, and compressor nasi; but neither of these muscles is inserted into it. SUPERIOR MAXILLARY BONES.—The superior maxillary are the largest bones of the face, with the exception of the lower jaw; they form, by their union, the whole of the upper jaw, and assist in the construction of the nose, the orbit, the cheek, and the palate. Each bone is divisible into a body and four processes. 42 SUPERIOR MAXILLARY BONES. Fig. 23." The body is triangular in form, and hollowed in its interior into a large cavity, the antrum maa- illare (antrum of Highmore). It presents for examination four sur- faces, external or facial, internal or nasal, posterior or zygomatic, and superior or orbital. The external, or facial surface, forms the anterior part of the bone ; it is irregularly concave, and pre- sents a deep depression towards its centre, the canine fossa, which gives attachment to two muscles, the com- pressor nasi and levator anguli oris. Immediately above this fossa is the infra-orbital foramen, the termina- tion of the infra-orbital canal, trans- mitting the superior maxillary nerve, and infra-orbital artery; and above the infra-orbital foramen, the lower margin of the orbit, continuous externally with the rough arti- cular surface of the malar process, and internally with a thick ascend- ing plate, the nasal process. Towards the middle line of the face this surface is bounded by the concave border of the opening of the nose, which is projected forwards at its inferior termination into a sharp process, forming, with a similar process of the opposite bone, the na- sal spine. Beneath the nasal spine, and above the two superior incisor teeth, is a slight depression, the incisive, or myrtiform fossa, which gives origin to the depressor labii superioris alaeque nasi muscle. The myrtiform fossa is divided from the canine fossa by a perpen- dicular ridge, corresponding with the direction of the root of the canine tooth, The inferior boundary of the facial surface is the alveolar process which contains the teeth of the upper jaw ; and it is separated from the zygomatic surface by a strong projecting eminence, the malar process. The internal, or nasal surface, presents a large irregular opening, leading into the antrum maxillare ; this opening is nearly closed in the * The superior maxillary bone of the right side, as seen from the lateral aspect. 1. The external, or facial surface ; the depression in which the figure is placed is the canine fossa, 2. The posterior, or zygomatic surface. 3. The superior, or orbital surface. 4. The infra-orbital foramen ; it is situated imme- diately below the number. 5. The infra-orbital canal, leading to the infra- orbital foramen. 6. The inferior border of the orbit. 7. The malar process. 8. The nasal process. 9. The concavity forming the lateral boundary of the anterior nares. 10. The nasal spine. 11. The incisive, or myrtiform fossa. 12. The alveolar process. 13. The internal border of the orbital surface, which articulates with the ethmoid and palate bone. 14. The concavity which arti- culates with the lachrymal bone, and forms the commencement of the nasal duct. 15 The crista nasalis of the palate process. i. The two incisor teeth. e. The canine. 4. The two bicuspidati. m. The three molares, —_— SUPERIOR MAXILLARY BONES: 43 articulated skull by the ethmoid, palate, lachrymal, and inferior turbi- nated bones. The cavity of the antrum is somewhat triangular, corre- sponding in shape with the form of the body of the bone. Upon its inner wall are numerous grooves, lodging branches of the superior max- illary nerve, and projecting into its floor several conical processes, corre- sponding with the roots of the first and second molar teeth. In front of the opening of the antrum is the strong ascending plate of the nasal process, marked inferiorly by a rough horizontal ridge (crista turbina- lis inferior), which gives atfachment to the inferior turbinated bone. The concave depression immediately above this ridge corresponds with the middle meatus of the nose, and that below the ridge with the in- ferior meatus. Between the nasal process and the opening of the antrum, is a deep groove (sulcus lachrymalis) which is converted into a canal by the lachrymal and inferior turbinated bone, and con- stitutes the nasal duct. The superior border of the nasal surface is irregularly cellular, and articulates with the lachrymal and ethmoid bone ; the posterior border is rough, and articulates with the palate bone ; the anterior border is sharp, and forms the free margin of the opening of the nose ; and from the inferior border projects inwards a strong horizontal plate, the palate process. The posterior surface may be called zygomatic, from forming part of the zygomatic fossa; it is bounded externally by the malar process, and internally by a rough and rounded border, the tuberosity, which is pierced by a number of small foramina (foramina alveolaria posteriora), giving passage to the posterior dental nerves and branches of the superior dental artery. The lower part of this tuberosity presents a rough oval surface, to articulate with the palate bone, and immediately above and to the inner side of this articular surface a smooth groove, which forms part of the posterior palatine canal. The superior border is smooth and rounded to form the lower boundary of the spheno- maxillary fissure, and is marked by a notch, the commencement of the infra-orbital canal. The inferior boundary is the alveolar process, containing the two last molar teeth. The orbital surface is triangular and thin, and constitutes the floor of the orbit. It is bounded internally by an irregular edge, which articulates with the palate, ethmoid, and lachrymal bone ; posteriorly, by the smooth border which enters into the formation of the spheno- maxillary fissure ; and, anteriorly, by a convex margin, partly smooth and partly rough, the smooth portion forming part of the lower margin of the orbit, and the rough articulating with the malar bone. The middle of this surface is channelled by a deep groove and canal, the infra-orbital, which terminates at the infra-orbital foramen ; and near to the root ‘of the nasal process is a slight depression, oe the origin of the inferior oblique muscle of the eyeball. The four processes of the superior maxillary bone are the nasal, malar, alveolar, and palate. The nasal process ascends by the side of the nose, to which it forms the lateral boundary, and articulates with the frontal and nasal bone. 44 LACHRYMAL BONES. By its external surface it gives attachment to the levator labii supe- rioris aleeque nasi, and to the orbicularis palpebrarum muscle. Its internal surface contributes to form the inner wall of the nares, and is marked transversely by a horizontal ridge (crista turbinalis superior) which divides it into two portions, one above the ridge irregular and uneven, for giving attachment to and completing the cells of the la- teral mass of the ethmoid ; the other below, smooth and concave, cor- responding with the middle meatus. The posterior border is thick and hollowed into a groove for the nasal, duct. The margin of the nasal process, which is continuous with the lower border of the orbit, is sharp and marked by a small tubercle which serves as a guide to the introduction of the knife in the operation for fistula lachrymalis. The malar process, large and irregular, is situated at the angle of separation between the facial and zygomatic surfaces, and presents a triangular surface for articulation with the malar bone. The alveolar process forms the lower margin of the bone; it is spongy and cellular in texture, and excavated into deep holes for the reception of eight teeth. The palate process is thick and strong, and projects horizontally inwards from the inner surface of the body of the bone. Superiorly, it is concave and smooth, and forms the floor of the nares ; inferiorly, it is also concave but uneven, and assists in the formation of the roof of the palate. This surface is marked by a deep groove, which lodges the posterior palatine nerve and artery. Its internal edge is raised into a ridge (crista nasalis), which, with a corresponding ridge in the opposite bone, forms a groove for the reception of the vomer. ‘The pro- longation of this ridge forwards beyond the level of the facial surface of the bone is the nasal spine. At the anterior extremity of its nasal surface is a foramen, which leads into a canal formed conjointly by the two superior maxillary bones, the anterior palatine canal. The termination of this canal is situated immediately behind the incisor teeth, hence it is also named the incisive foramen. Associated with the incisive openings and canal are two smaller canals, the naso-pala- tine, which transmit the naso-palatine nerves. These canals are situated in the walls of the incisive canal, and terminate inferiorly in that canal, either by separate openings or conjoined. Development.—By four centres; one for the anterior part of the _ palate, and incisive portion of the alveolar process (the permanence of this piece constitutes the intermaxillary bone of animals); one for that portion of the bone lying internally to the infra-orbital canal and fora- men; one for that portion lying externally to the groove and canal ; and one for the palate process. The superior maxillary bone is one of the earliest to shew signs of ossification, this process beginning in the alveolar process, and being associated with the early development of teeth. The early development of the alveolar process, and the conse- quent fusion at this point of the original pieces, explains the diffi- culties which have been felt by anatomists in determining the precise number of the ossifying centres, MALAR BONES. 45 Articulations. — With nine bones, viz.; with two of the cranium and with all the bones of the face excepting the inferior maxillary. These are, the frontal and ethmoid, nasal, lachrymal, malar, inferior turbinated, palate, vomer, and its fellow of the opposite side. Attachment of muscles —To nine ; orbicularis palpebrarum, obliquus inferior oculi, levator labii superioris alzeque nasi, levator labii supe- . rioris proprius, levator anguli oris, compressor nasi, depressor labii superioris aleeque nasi, buccinator, masseter. LacHRYMAL Bones—(os unguis, from an imagined resemblance to a finger nail). The lachrymal is a thin oval-shaped plate of bone, situated at the anterior and inner angle of the orbit. It may be di- vided into an external and internal surface and four borders. The eaternal surface is smooth and marked by a vertical ridge, the lachrymal crest, into two portions, one of which is flat and enters into the formation of the orbit, hence may be called the orbital portion ; the other is concave, and lodges the lachrymal sac, hence the lachrymal portion. The crest is expanded inferiorly into a hook- shaped process (hamulus lachrymalis) which ‘forms part of the outer boundary of the fossa lachrymalis. The internal surface is uneven and completes the anterior ethmoid cells, it assists also in forming the wall of the nasal fossze and nasal duct. The four borders articulate with adjoining bones. Development.—By a single centre appearing in the early part of the third month. Articulations —With four bones ; two of the cranium, frontal and ethmoid ; and two of the face, superior maxillary, and inferior tur- binated bone. Attachment of Muscles——To one muscle, the tensor tarsi, and to an expansion of the tendo oculi, the former arising from the orbital sur- face, the other being attached to the lachrymal crest. Matar Bones—(mala, the cheek). The malar (fig. 28) is the strong quadrangular bone which forms the prominence of the cheek. It is divisible into an external and internal surface and four processes, the frontal, orbital, maxillary, and zygomatic. The eaternal surface is * The lachrymal bone of the right side, viewed upon its external or orbital surface. 1. The orbital portion of the bone. 2. The lachrymal portion ; the prominent ridge between these two portions is the crest. 3. The lower ter- mination of the crest, the hamulus lachrymalis. 4. The superior border which articulates with the frontal bone. 5. The posterior border, which articulates with the ethmoid bone, 6. The anterior border which articulates with the su- pone Lea rage bone. 7. The border which articulates with the inferior tur- inated bone. 46 PALATE BONES. smooth and convex, and pierced by several small openings which give passage to filaments of the temporo-malar nerve and minute arteries. The internal surface is concave, partly smooth and partly rough ; smooth where it forms part of the temporal fossa, and rough where it articulates with the superior maxillary bone. The frontal process ascends perpendicularly to form the outer border of the orbit, and to articulate with the external angular process of the frontal bone. The orbital process is a thick plate, which projects inwards from the frontal process, and unites with the great ala of the sphenoid to constitute the outer wall of the orbit. It is pierced by several small foramina for the passage of temporo-malar filaments of the superior maxillary nerve. The mazillary process is broad, and articulates with the superior maxillary bone. The zygomatic process, narrower than the rest, projects backwards to unite with the zygoma of the temporal bone. Development.—By a single centre ; rarely by two or three. In many animals the malar bone is permanently divided into two por- tions, orbital and malar. Ossification commences in the malar bone soon after the vertebree. Articulations.—With four bones; three of the cranium, frontal, temporal, and sphenoid ; and one of the face, the superior maxillary bone. Attachment of Muscles——To five ; levator labii superioris proprius, zygomaticus minor and major, masseter, and temporal. BR ME PataTE Bones.—The palate bones are situated at the posterior part of the nares, where they enter into the formation of the palate, the side of the nose, and the posterior part of the floor of the orbit; hence they might with great propriety be named the pa- lato-naso-orbital bones. Each bone re- sembles in general form the letter L, and is divisible into a horizontal plate, a perpendicular plate, and a pterygoid process or tuberosity. The horizontal plate is quadrilateral ; and presents two surfaces, one superior, which enters into the formation of the floor of the nares, the other inferior, forming the posterior part of the hard palate. The superior surface * A posterior view of the right palate bone in its natural position; it is slightly turned to one side to obtain a sight of the internal surface of the per- norman plate (2). 1. The horizontal plate of the bone; its upper or nasal surface. 2. The perpendicular plate ; Boh een or nasal surface. 3, 10, 11. The pterygoid Eich a or tuberosity. 4. The thick internal border of the hori- zontal plate, which, articulating with the similar border of the opposite bone, PALATE BONES. 47 is concave and rises towards the middle line, where it unites with its fellow of the opposite side and forms part of a crest (crista nasalis), which articulates with the vomer. The inferior surface is uneven, and marked by a slight transverse ridge, to which is attached the tendinous expansion of the tensor palati muscle. Near to its external border are two openings, one large and one small, the posterior palatine foramina; the former transmits the posterior pala- tine nerve and artery, and the latter the middle palatine nerve. The posterior border is concave, and presents at its inner extremity a sharp point, which with a corresponding point in the opposite bone constitutes the palate spine for the attachment of the azygos uvule muscle. The perpendicular plate is also quadrilateral ; and presents two sur- faces, one internal or nasal, forming a part of the wall of the nares ; the other external, bounding the spheno-maxillary fossa and antrum. The internal surface is marked near its middle by a horizontal ridge (crista turbinalis inferior), to which is united the inferior turbinated bone, and at about half an inch above this by another ridge (crista turbinalis superior) for the attachment of the middle turbinated bone. The concave surface below the inferior ridge is the lateral boundary of the inferior meatus of the nose; that between the two ridges corre- sponds with the middle meatus, and the surface above the superior _Tidge with the superior meatus. The external surface, extremely irre- gular, is rough on each side for articulation with neighbouring bones, and smooth in the middle to constitute the inner boundary of the spheno-maxillary fossa. This smooth surface terminates inferiorly in a deep groove, which being completed by the tuberosity of the su- perior maxillary bone and pterygoid process of the sphenoid, forms the posterior palatine canal. Near the upper part of the perpendicular plate is a large oval notch completed by the sphenoid, the spheno-palatine foramen, which trans- mits the spheno-palatine nerves and artery, and serves to divide the upper extremity of the bone into two portions, an anterior or orbital, and a posterior or sphenoidal portion. The orbital portion is hollow within, and presents five surfaces externally ; three articular, and two free ; the three articular are the anterior, which looks forward and articulates with the superior maxillary bone, internal with the ethmoid, and posterior with the sphenoid. The free surfaces are the superior or orbital, which forms the posterior part of the floor of the orbit, and forms the crista nasalis for the reception of the vomer. 5. The pointed pro- cess, which with a similar process of the opposite bone forms the palate spine. 6. The horizontal ridge which gives attachment to the inferior turbinated bone; the concavity below this ridge enters into the formation of the inferior meatus, and the concavity (2) above the ridge into that of the middle meatus. 7. The spheno-palatine notch. 8. The orbital portion. 9. The crista turbinalis supe- rior for the middle turbinated bone. 10. The middle facet of the tuberosity, which enters into the formation of the pterygoid fossa. The facets 11 and 3 articulate with the two pterygoid plates, 11 with the internal, and 3 with the external. 48 INFERIOR TURBINATED BONES. the external, which looks into the spheno-maxillary fossa. The sphenoidal portion, much smaller than the orbital, has three surfaces, two lateral and one superior. The ex- ternal lateral surface enters into the formation of the spheno-maxillary fos- sa; the internal lateral forms part of the lateral boundary of the nares ; and the superior surface articulates with the under part of the body of the sphe- noid bone, and assists the sphenoidal spongy bones in closing the sphenoidal sinuses. This portion takes part in canal. The pterygoid process or tuberosity of the palate bone is the thick and rough process which stands backwards from the angle of union of the horizontal with the perpendicular por- tion of the bone. It is received into the angular fissure, which exists between the two plates of the pterygoid process at their inferior extre- mity, and presents three surfaces: one concave and smooth, which forms part of the pterygoid fossa; and one at each side to articulate with the pterygoid plates. The anterior face of this process is rough and articulates with the superior maxillary bone. Development.—By a single centre, which appears in the angle of union between the horizontal and perpendicular portion, at the same time with ossification in the vertebra. Articulations.—W ith siz bones ; two of the cranium, the sphenoid and ethmoid ; and four of the face, the superior maxillary, inferior turbinated bone, vomer, and the palate bone of the opposite side. Attachment of Muscles—To four ; the tensor palati, azygos uvule, internal and external pterygoid. INFERIOR TURBINATED BONES.—The inferior turbinated or spongy bone, is a thin layer of light and porous bone, attached to the crista turbinalis inferior of the inner wall of the nares, and projecting in- wards towards the septum narium. The inferior turbinated bone is broad in front, narrow and tapering behind, and slightly curled upon itself, so as to bear some resemblance to one valve of a bivalve shell, * The perpendicular plate of the palate bone seen upon its external or spheno- maxillary surface. 1. The — surface of this plate, which articulates with the superior maxillary bone and bounds the antrum. 2. The posterior palatine canal, completed by the tuberosity of the superior maxillary bone and pterygoid rocess. The rough surface to the left of the canal (2) articulates with the internal peek aes plate. 3. The spheno-palatine notch. 4, 5, 6. The orbital portion of the perpendicular plate. 4. The spheno-maxillary facet of this por- tion; 5. its orbital facet; 6. its maxillary facet, to articulate with the superior maxillary bone. 7 The sphenoidal portion of the perpendicular plate. 8. The pterygoid process or tuberosity of the bone. the formation of the pterygo-palatine VOMER, 49 hence its designation concha inferior. The bone presents for examina- tion a convex and concave surface, and a superior and inferior border. The convea surface looks inwards and upward, and forms the inferior boundary of the middle meatus naris ; it is marked by several longi- tudinal grooves for branches of the sphenopalatine nerve and artery. The concave surface looks downwards and outwards, and constitutes the roof of the inferior meatus. The superior border is irregular; it is attached to the crista turbinalis inferior of the superior maxillary bone in front, to the same crest on the palate bone behind, and be- tween those attachments gives off two, and sometimes three, thin and laminated processes. The most anterior of these processes, processus lachrymalis, articulates with the lachrymal bone, and assists in com- pleting the nasal duct. The middle process, processus mazillaris, de- scends and assists in closing the antrum maxillare; while the posterior, processus ethmoidalis, which is often wanting, ascends towards the ethmoid bone, and also takes part in the closure of the antrum maxil- lare. The inferior border is rounded, and thicker than the rest of the bone. Development.—By a single centre which appears at about the middle of the first year... It affords no attachment to muscles. Articulations.—W ith four bones ; the ethmoid, superior maxillary, lachrymal, and palate. Vomer.—The vomer is a thin quadrilateral plate of bone, forming the posterior and inferior part of the septum of the nares. The superior border is broad and expanded to articulate, in the middle with the under surface of the body of the sphenoid, and on each side with the processus vaginalis of the pterygoid process, The anterior part of this border is hollowed into a sheath for the reception of the rostrum of the sphenoid. The inferior border is thin and irregular, and is received into the grooved summit of the crista nasalis. The posterior border is sharp and free and forms the posterior division of the two nares. The anterior border is more or less deeply grooved for the reception of the central lamella of the ethmoid and cartilage of the septum. This groove is an indication of the early constitution of the bone of two lamellz, united at the inferior border. The vomer not unfrequently presents a convexity to one or the other side, generally it is said, to the left. Development.—By a single centre, which makes its appearance at the same time with those of the vertebra. Ossification begins from below and proceeds upwards. At birth the vomer presents the form of a trough in the concavity of which the cartilage of the septum nasi is placed ; it is this disposition which subsequently enables the bone to embrace the rostrum of the sphenoid. The vomer has no muscles attached to it. Articulations.— With siz bones ; the sphenoid, ethmoid, two superior maxillary, and two palate bones, and with the cartilage of the septum. E 50 INFERIOR MAXILLARY BONE. INFERIOR MAXILLARY BONE.—The lower jaw is the arch of bone which contains the inferior teeth ; it is divisible into a horizontal portion or body, and a perpendicular portion, the ramus, at each side. Upon the external surface of the body of the bone, at the middle line, and extending from between the two first incisor teeth to the chin, is a slight ridge, crista mentalis, which indicates the point of conjunction of the lateral halves of the bone in the young subject, the symphysis. Immediately external to this ridge is a depression which gives origin to the depressor labii inferioris muscle ; and corresponding with the root of the lateral incisor tooth, another depression, the incisive fossa, for the levator labii inferioris. Further outwards is an oblique opening, the mental foramen, for the exit of the inferior dental nerve and artery, and below this foramen, the commencement of an oblique ridge which runs upwards and outwards to the base of the coronoid process and gives attachment to the depressor anguli oris, platysma myoides, and buccinator muscles. Near to the posterior part of this surface is a rough impression made by the masseter muscle ; and immediately in front of this impression, a groove may occasionally be seen for the facial artery. The projecting tuberosity at the posterior extremity of the lower jaw, at the point where the body and ramus meet, is the angle. Upon the internal surfuce of the body of the bone at the symphysis, are two small pointed tubercles; immediately beneath these, two other tubercles less marked and pointed, beneath them a ridge, and beneath the ridge two rough depressions of some size. These four points give at- tachment from above downwards to the genio-hyo-glossi, genio-hyoidei, part of the mylo-hyoidei and to the digastric muscles. Running out- wards into the body of the bone from the above ridge is a prominent line, the mylo-hyoidean ridge, which gives attachment to the mylo-hyoideus muscle, and by its extremity to the pterygo-maxillary ligament and superior constrictor muscle. Immediately above the ridge, and by the side of the symphysis, is a smooth concave surface, which cor- responds with the sublingual gland ; and below the ridge, and more externally, a deeper fossa for the submaxillary gland. The superior border of the body of the bone is the alveolar process, furnished in the adult with alveoli for sixteen teeth. The inferior border or base is rounded and smooth ; thick and everted in front to form the chin, and thin behind where it merges in the angle of the bone. The ramus is a strong square-shaped process, differing in direc- tion at various periods of life; thus, in the foetus and infant, it is almost parallel with the body; in youth it is oblique, and gradually increases in the vertical direction until manhood; in old age, after the loss of the teeth, it again declines and assumes the oblique direction. Upon its external surface it is rough, for the attachment of of the masseter muscle ; and at the junction of its posterior border with the body of the bone, is a rough tuberosity, the angle of the INFERIOR MAXILLARY BONE. 51 lower jaw, which gives attachment by its inner margin to the stylo- maxillary ligament. The upper extremity of the ramus presents two processes, separated by a concave sweep, the sigmoid notch. The anterior is the coronoid process; it is sharp and pointed, and gives attach- 20 ment by its inner surface Fig. 27.* tothe temporal muscle, The iy | anterior border of the coro- noid process is grooved at its lower part for the buc- cinator muscle. The poste- rior process is the condyle of the lower jaw, which is flattened from before back- wards, oblique in direction, and smooth upon its upper surface, to articulate with the glenoid cavity of the temporal bone. The con- striction around the base of the condyle is its neck, into which is inserted the external pterygoid muscle. The sigmoid notch is crossed by the masseteric artery and “nerve. The internal surface of the ramus is marked near its centre by a large oblique foramen, the inferior dental, for the entrance of the inferior dental artery and nerve into the dental canal. Bounding this opening is a sharp margin, to which is attached the internal lateral ligament, and passing downwards from the opening a narrow groove which lodges the mylo-hyoidean nerve with a small artery and vein. To the uneven surface above, and in front of the inferior dental fora- men, is attached the temporal muscle, and to that below it the internal pterygoid. The internal surface of the neck of the condyle gives at- tachment to the external pterygoid muscle ; and the angle to the stylo-maxillary ligament. Development.—By two centres ; one for each lateral half, the two sides meeting at the symphysis, where they become united. The lower jaw is the earliest of the bones of the skeleton to exhibit ossifi- cation, with the exception of the clavicle ; ossific union of the sym- physis takes place during the first year. * The lower jaw. 1. The body. 2, The ramus. 3. The symphysis. 4. The fossa for the depressor labii inferioris muscle. 5. The mental foramen. 6. The external oblique ridge. 7. The groove for the facial artery ; the situa- tion of the groove is marked by a notch in the bone a little in front of the num- ber. 8. The angle. 9. The extremity of the mylo-hyoidean ridge. 10. The coronoid process. 11. The condyle. 12. The sigmoid notch. 13. The inferior dental foramen. 14. The mylo-hyoidean groove. 15. The alveolar process. t. The middle and lateral incisor tooth of one side. ec. The canine tooth. 4. The two bicuspides. m. The three molares, 52 TABLE OF DEVELOPMENTS, ARTICULATIONS, ETC. Articulations —W ith the glenoid fossee of the two temporal bones, through the medium of a fibro-cartilage. . Attachment of Muscles.—To fourteen pairs ; by the external surface commencing at the symphysis, and proceeding outwards, — levator labii inferioris, depressor labii inferioris, depressor anguli oris, pla- tysma myoides, buccinator, and masseter ; by the internal surface also commencing at the symphysis, the genio-hyo-glossus, genio-hyoideus, mylo-hyoideus, digastricus, superior constrictor, temporal, external pterygoid, and internal pterygoid. Table shewing the Points of Development, Articulations, and Attach- ment of Muscles, of the Bones of the Head. Attachment of Development. Articulations. muscles. Occipital : 7 ‘ 6 13 pairs. Parietal ] 5 1 muscle. Frontal 2 12 3 pairs. Temporal . 5 5 14 muscles. Sphenoid . 12 12 12 pairs. Ethmoid . 3 . 13 ‘ none. Nasal , 3 1 ‘ 4 : none. Superior maxillary 6 9 ; 9 muscles. Lachrymal _ 1 4 | eee | Malar . 1 4 5 ib. Palate ‘ 1 6 4 ib. Inferior turbinated 1 4 none. Vomer 1 6 none. Lower jaw 2 2 14 pairs. SUTURES. The harmonia suture (dégeiv, to adapt) is the simple apposition of contiguous surfaces, the surfaces being more or less rough and reten- tive. This suture is seen in the connection between the superior maxillary bones, or of the palate processes of the palate bones with each other. SUTURES.—OSSA TRIQUETRA. 53 The -schindylesis suture (cxvd0anois, a fissure) is the reception of one bone into a sheath or fissure of another, as occurs in the articula- tion of the rostrum of the sphenoid with the vomer, or of the latter with the perpendicular lamella of the ethmoid, and with the crista nasalis of the superior maxillary and palate: bones. The serrated suture is formed by the interlocking of the radiating fibres along the edges of the flat bones of the cranium during growth. When this process is retarded in the infant by over distention of the head, as in hydrocephalus, and sometimes without any such apparent cause, distinct ossific centres are developed in the interval between the edges ; and, being surrounded by the suture, form independent pieces, which are called ossa triquetra, or ossa Wormiana. In the lambdoid suture there is generally one or more of these bones ; and, in a beauti- ful adult hydrocephalic skeleton in the possession of Mr. Liston, there are upwards of one hundred. The coronal suture (fig. 28) extends transversely across the vertex of the skull, from the upper part of the greater wing of the sphenoid to the same point on the opposite side; it connects the frontal with the parietal bones. In the formation of this suture the edges of the articulating bones are bevelled, so that the parietal rest upon the frontal at each side, and in the middle the frontal rests upon the parietal bones; they thus afford each other mutual support in the consolidation of the skull. The sagittal suture (fig. 28) extends longitudinally backwards along the vertex of the skull, from the middle of the coronal to the apex of the lambdoid suture. It is very much serrated, and serves to unite the two parietal bones. In the young subject, and sometimes in the adult, this suture is continued through the middle of the frontal bone to the root of the nose, under the name of the frontal suture. Ossa triquetra are sometimes found in the sagittal suture. The lambdoid suture is named from some resemblance to the Greek letter A, consisting of two branches, which diverge at an acute angle from the extremity of the sagittal suture. This suture connects the occipital with the parietal bones. At the posterior and inferior angle of the parietal bones, the lambdoid suture is continued onwards in a curved direction into the base of the skull, and serves to unite the occipital bone with the mastoid portion of the temporal, under the name of the additamentum suture lambdoidalis. It is in the lambdoid suture that ossa triquetra occur most frequently. The squamous suture (fig. 28) unites the squamous portion of the temporal bone with the greater ala of the sphenoid and-with the parietal, overlapping the lower border of the latter. The portion of the suture which is continued backwards from the squamous portion of the bone to the Jambdoid suture, and connects the mastoid portion with the posterior inferior angle of the parietal, is the additamentum suture squamose. The additamentum suture lambdoidalis and additamentum suture squamose, constitute together the mastoid suture. 54 SUPERIOR REGION OF THE SKULL. Across the upper part of the face is an irregular suture, the trans- verse, which connects the frontal bone with the nasal, superior maxillary, lachrymal, ethmoid, sphenoid, and malar bones. The other sutures are too unimportant to deserve particular names or description. REGIONS OF THE SKULL. The skull, considered as a whole, is divisible into four regions,—a superior region, or vertex ; a lateral region ; an inferior region, or base ; and an anterior region, the face. Fig. 28.* N \ The SUPERIOR REGION, or vertex of the skull, is bounded anteriorly by the frontal eminences ; on each side by the temporal ridges and parietal eminences ; and behind by the superior curved line of the * A front view of the skull. 1. The frontal portion of the frontal bone. The 2, immediately over the root of the nose, refers to the nasal tuberosity ; the 3, over the orbit, to the supra-orbital ridge. 4. The optic foramen. 5. The sphenoidal fissure. 6. The spheno-maxillary fissure. 7. The lachrymal fossa in the lachrymal bone, the commencement of the nasal duct. The figures 4, 5, 6, 7, are within the orbit. 8. The opening of the anterior nares, divided into two arts by the vomer; the number is placed upon the latter. 9. The infra-orbital oramen. 10. The malarbone. 11. The symphysis of the lower jaw. 12. The mental foramen. 13. The ramus of the lower jaw. 14.-The parietal bone. 15. The coronal suture. 16. The temporal bone. 17. The squamous suture. 18. The upper part of the great ala of the sphenoid bone. 19. The commence- ment of the temporal ridge. 20. The zygoma of the temporal bone, assisting to form the zygomatic arch. 21. The mastoid process. SUPERIOR REGION OF THE SKULL. 55 occipital bone and occipital protuberance. It is crossed transversely by the coronal suture, and marked from before backwards by the sagittal, which terminates posteriorly in the lambdoid suture. Near ‘Fig. 29.* the posterior extremity of the region, and on each side of the sagittal suture, is the parietal foramen. Upon the inner, or cerebral surface of this region is a shallow groove, extending along the middle line from before backwards, for the superior longitudinal sinus ; on either side of this groove are * The cerebral surface of the base of the skull. 1. One side of the anterior fossa; the number is placed on the roof of the orbit, formed by the orbital plate of the frontal bone. 2. The lesser wing of the sphenoid. 3. The crista |. 4. The foramen cecum. 5. The cribriform lamella of the ethmoid. 6. The processus olivaris. 7. The foramen opticum. 8g. The anterior clinoid process. 9. The carotid groove upon the side of the sella turcica, for the in- ternal carotid artery and cavernous sinus. 10, 11, 12. The middle fossa of the base of the skull. 10. Marks the great ala of the sphenoid. 11. The squamous portion of the temporal bone. 12. The petrous portion of the tem- poral. 13. The sella turcica. 14. The basilar portion of the sphenoid and occipital bone (clivus Blumenbachii). The uneven ridge between Nos. 13, 14, is the dorsum ephippii, and the prominent angles of this process the posterior clinoid processes. 15 The foramen rotundum, 16. The foramen ovale. 17. The foramen spinosum ; the small irregular opening between 17 and 12 is the hiatus Fallopii. 18. The posterior fossa of the base of the skull. 19, 19. The groove for the lateral sinus, 20. The ridge upon the occipital bone, which gives attachment to the falx cerebelli. 21. The foramen magnum, 22. The meatus auditorius internus. 23. The jugular foramen.. 56 BASE OF THE SKULL. several small fossze for the Pacchionian bodies, and further outwards digital fossee corresponding with the convexities of the convolutions and numerous ramified markings for lodging the branches of the arteria meningea media. . The LATERAL REGION of the skull is divisible into three portions ; temporal, mastoid, and zygomatic. The temporal portion, or temporal fossa, is bounded above and behind by the temporal ridge, in front by the external angular process of the frontal bone and by the malar bone, and below by the zygoma. It is formed by part of the frontal, great wing of the sphenoid, parietal, squamous portion of the temporal, malar bone and zygoma, and lodges the temporal muscle with the deep temporal arteries and nerves, The mastoid portion is rough, for the attachment of muscles. Upon its posterior part is the mastoid foramen, and below, the mastoid pro- cess. In front of the mastoid process is the external auditory fora- men, surrounded by the external auditory process ; and in front of this foramen the glenoid cavity, bounded above by the middle root of the zygoma and in front by its tubercle. The zygomatic portion, or fossa, is the irregular cavity below the zygoma, bounded in front by the superior maxillary bone, inter- nally by the external pterygoid plate, above by part of the great wing of the sphenoid and squamous portion of the temporal bone, and . by the temporal fossa, and externally by the zygomatic arch and ramus of the lower jaw. It contains the external pterygoid, with part of the temporal and internal pterygoid muscle, and the internal maxillary artery and inferior maxillary nerve, with their branches. At the bottom of the zygomatic fossa are two fissures, the spheno-maxillary and the pterygo-maxillary. The spheno-maaillary fissure is horizontal in direction, opens into the orbit, and is situated between the great ala of the sphenoid and the superior maxillary bone. It is completed externally by the malar bone. The pterygo-maaillary fissure is verti- cal, and descends at right angles from the extremity of the preceding. It is situated between the pterygoid process and the tuberosity of the superior maxillary bone, and transmits the internal maxillary artery. At the angle of junction of these two fissures is a’ small cavity, the spheno-mazxillary fossa, bounded by the sphenoid, palate, and superior maxillary bones, in which are seen the openings of five foramina,— the foramen rotundum, spheno-pfalatine, pterygo-palatine, posterior palatine, and Vidian. It lodges Meckel’s ganglion and the termina- tion of the internal maxillary artery. The BASE OF THE SKULL presents an internal or cerebral, and an external or basilar surface. The cerebral surface is divisible into three parts, which are named the anterior, middle, and posterior fossa of the base of the cranium. The anterior fossa is somewhat convex on each side, where it cor- responds with the roofs of the orbits ; and concave in the middle, in the situation of the ethmoid bone and the anterior part of the body of the sphenoid. The latter and the lesser wings constitute its posterior a we el BASE OF THE SKULL. 57 boundary. It supports the anterior lobes*of the cerebrum. In the middle line of this fossa, at its anterior part, is the crista galli, im- mediately in front of this process, the foramen cecum, and on each side the cribriform plate, with its foramina, for the transmission of the filaments of the olfactory and nasal branch of the ophthalmic nerve. Farther back in the middle line is the processus olivaris, and on the sides of this process the optic foramina, anterior and middle clinoid processes, and vertical grooves for the internal carotid arteries. The middle fossa of the base, deeper than the preceding, is bounded in front by the iesser wing of the sphenoid ; behind, by the petrous portion of the temporal bone ; and is divided into two lateral parts by the sella turcica. It is formed by the posterior part of the body, great ala, and spinous process of the sphenoid, and by the petrous and squamous portion of the temporal bones. In the centre of this fossa is the sella turcica which lodges the pituitary gland, bounded in front by the anterior and middle and behind by the posterior clinoid processes. On each side of the sella turcica is the carotid groove for the internal carotid artery, the cavernous plexus of nerves, the cavernous sinus, and the orbital nerves, and a little farther outwards the following foramina from before backwards, sphenoidal fissure (fora- men lacerum anterius) for the transmission of the third, fourth, three branches of the ophthalmic division of the fifth, and the sixth nerve, and ophthalmic vein ; foramen rotwndum, for the superior maxillary nerve ; foramen ovale, for the inferior maxillary nerve, arteria menin- gea parva, and nervus petrosus superficialis minor ; foramen spinosum, for the arteria meningea media ; foramen lacerum basis cranti, which gives passage to the internal carotid artery, carotid plexus, and petrosal branch of the Vidian nerve. On the anterior surface of the petrous portion of the temporal bone is a groove, leading to a fissured opening, the hiatus Fallopii, for the petrosal branch of the Vidian nerve ; and immediately beneath this a smaller foramen, for the nervus petrosus superficialis minor. Towards the apex of this portion of bone is the notch for the fifth nerve, and below it a slight depres- sion for the Casserian ganglion. Farther outwards is the eminence which marks the position of the perpendicular semi-circular canal. Proceeding from the foramen spinosum are two grooves which indicate the course of the trunks ‘of the arteria meningea media. The whole fossa lodges the middle lobes of the cerebrum. The posterior fossa, larger than the other two, is formed by the occipital bone, by the petrous and mastoid portion of the temporals, and by a small part of the sphenoid and parietals. It is bounded in front by the upper border of the petrous portion and dorsum ephippii, and along its posterior circumference by the groove for the lateral sinuses; it gives support to the pons Varolii, medulla oblongata and cerebellum. In the centre of this fossa is the foramen magnum bound- ed on each side by a rough tubercle, which gives attachment to the odontoid ligament, and by the anterior condyloid foramen. In front of the foramen magnum is the concave surface (clivus Blumenbachii) 58 BASE.OF THE SKULL. which supports the medulla oblongata and pons Varolii, and on each side the following foramina from before backwards. The internal auditory foramen, for the auditory and facial nérve and auditory artery ; behind, and external to this is a small foramen leading into Fig. 30.* (it Pal : Sia the aqueductus vestibuli ; and below it, partly concealed by the edge of the petrous bone, the agueductus cochlee ; next, a long fissure, the foramen lacerum posterius, or jugular foramen, giving passage ex- * The external or basilar surface of the base of the skull. 1, 1. The hard alate. The figures are placed upon the palate processes of the superior max- illary bones. 2. The incisive, or anterior palatine foramen. 3. The palate process of the palate bone. The large opening near the figure is the posterior alatine foramen. 4. The palate spine; the curved line upon which the num- er rests, is the transverse ridge. 5. The vomer, dividing the openings of the osterior nares. 6. The internal pterygoid plate. 7. The scaphoid fossa. 8. e external pterygoid plate. The interval between 6 and 8 (right side of the figure), is the pterygoid fossa. 9. The zygomatic fossa, 10. The basilar pro- cess of the occipital bone. 11. The foramen magnum. 12. The foramen ovale. 13. The foramen spinosum. 14. The glenoid fossa. 15. The meatus auditorius externus. 16. The foramen lacerum anterius basis cranii. 17. The carotid foramen of the left side. 18. The foramen lacerum posterius, or jugu- lar foramen. 19. The styloid process. 20. The stylo-mastoid foramen. 21. The mastoid process. 22. One of the condyles of the occipital bone. 23. The posterior condyloid fossa. ‘BASE OF THE SKULL. 59 ternally to the commencement of the internal jugular vein and in- ternally to the eighth pair of nerves. Converging towards this fora- men from behind is the deep groove for the lateral sinus, and from the front the groove for the inferior petrosal sinus. Behind the foramen magnum is a longitudinal ridge, which gives attachment to the falx cerebelli, and divides the two inferior fossz of the occipital bone ; and above the ridge is the internal occipital pro- tuberance and the transverse groove lodging the lateral sinus. The eaternal surface of the base of the skull is extremely irregular. From before backwards it is formed by the palate processes of the superior maxillary and palate bones ; the vomer ; pterygoid, spinous processes, and part of the body of the sphenoid ; under surface of the squamous, petrous, and mastoid portion of the temporals ; and by the occipital bone. The palate processes of the superior maxillary and palate bones constitute the hard palate, which is raised above the level of the rest of the base, and is surrounded by the alveolar processes containing the teeth of the upper jaw- At the anterior extremity of the hard palate, and directly behind the front incisor teeth, is the anterior palatine or incisive foramen, the termination of the anterior palatine canal, which contains the naso-palatine ganglion, and trans- mits the anterior palatine nerves. At the posterior angles of the palate are the posterior palatine foramina, for the posterior palatine nerves and arteries. Passing inwards from these foramina are the transverse ridges to which are attached the expansions of the tensor palati muscles, and at the middle line of the posterior border the palate spine which gives origin to the azygos uvule. The hard palate is marked by a crucial suture, which distinguishes the four processes of which it is composed. Behind, and above the hard palate, are the posterior nares, separated by the vomer, and bounded on each side by the pterygoid processes. At the base of the pterygoid processes are the pterygo-palatine canals. The internal pterygoid plate is long and narrow, terminated at its apex by the hamular process, and at its base by the scaphoid fossa. The external plate is broad ; the space between the two is the pterygoid fossa; it contains part of the internal pterygoid muscle, and the tensor palati. Externally to the external pterygoid plate is the zygomatic fossa. Behind the nasal fosse, in the middle line, is the under surface of the body of the sphenoid, and the basilar process of the occipital bone, and, still further back, the foramen magnum. At the base of the external pterygoid plate, on each side, is the foramen ovale, and behind this the foramen spinosum with the prominent spine which gives attachment to the- internal lateral ligament of the lower jaw and the laxator tympani muscle. Running outwards from the apex of the spinous process of the sphenoid bone, is the fissura Glaseri, which crosses the glenoid fossa transversely, and divides it into an anterior smooth surface, bounded by the eminentia articularis, for the condyle of the lower jaw, and a posterior rough surface for a part of the parotid gland. Behind the foramen ovale and spinosum, is the irregular fissure between the 60 REGION OF THE FACE. spinous process of the sphenoid bone and the petrous portion of the temporal, the foramen lacerum anterius basis cranii, which lodges the _internal carotid artery and Eustachian tube, and in which the carotid branch of the Vidian nerve joins the carotid plexus. Following the direction of this fissure outwards is the foramen for the Eustachian tube, and that for the tensor tympani muscle, separated from each other by the processus cochleariformis. Behind the fissure is the pointed pro- cess of the petrous bone which gives origin to the levator palati muscle, and, externally to this process, the carotid foramen for the transmission of the internal carotid artery and the ascending branch of the superior cervical ganglion of the sympathetic; and behind the carotid foramen, the foramen lacerum posterius and jugular fossa. Externally, and somewhat in front of the latter, is the styloid process, and at its base the vaginal process. Behind and at the root of the styloid process is the stylo-mastoid foramen, for the facial nerve and stylo-mastoid artery, and further outwards the mastoid process. Upon the inner side of the root of the mastoid process is the digastric fossa ; and a little farther internally, the occipital groove. On either side of the foramen magnum, and near its anterior circumference, are the con- dyles of the occipital bone. In front of each condyle, and piercing its base, is the anterior condyloid foramen for the hypoglossal nerve, and directly behind the condyle the irregular fossa in which the posterior condyloid foramen is situated. Behind the foramen magnum are the two curved lines of the occipital bone, the spine, and protuberance, with the rough surfaces for the attachment of muscles. The Fac is somewhat oval in contour, uneven in surface, and excavated for the reception of two principal organs of sense,—the eye and the nose. It is formed by part of the frontal bone and by the bones of the face. Superiorly it is bounded by the frontal eminences ; beneath these are the superciliary ridges, converging towards the nasal tuberosity ; beneath the superciliary ridges are the supra-orbital ridges, terminating externally in the external border of the orbit, and inter- nally in the internal border, and presenting towards their inner third the supra-orbital notch, for the supra-orbital nerve and artery. Be- neath the supra-orbital ridges are the openings of the orbits. Between the orbits is the bridge of the nose, overarching the anterior nares; and on each side of this opening the canine fossa of the superior maxillary bone, the infra-orbital foramen, and still farther outwards the pro- minence of the malar bone ; at the lower margin of the anterior nares is the nasal spine, and beneath this the superior alveolar arch contain- ing the teeth of the upper jaw. Forming the lower boundary of the face is the lower jaw, containing in its alveolar process the lower teeth, and projecting inferiorly to form the chin; on either side of the chin is the mental foramen. If a perpendicular line be drawn from the inner third of the supra-orbital ridge to the inner third of the body of the lower jaw, it will be found to intersect three openings ;— the supra-orbital,. infra-orbital, and mental, each giving passage to a facial branch of the fifth nerve. 61 ORBITS. The orbits are two quadrilateral hollow cones, situated in the upper part of the face, and intended for the reception of the eye-balls, with their muscles, vessels, and nerves, and the lachrymal glands. The cen- tral axis of each orbit is directed outwards, so that the axes of the two continued into the skull through the optic foramina, would intersect over the middle of the sella turcica. The superior boundary of the orbit is formed by the orbital plate of the frontal bone, and by part of the lesser wing of the sphenoid; the inferior, by part of the malar bone and by the orbital processes of the superior maxillary and palate bone; the internal by the lachrymal bone, the os planum of the ethmoid and part of the body of the sphenoid ; and the eternal, by the orbital process of the malar bone and the great ala of the sphenoid ; these may be expressed more clearly in a tabular form :— Frontal. Sphenoid (lesser wing). Malar. i Lachrymal. Sphenoid (greater wing). Orbit. Ethmoid (os planum). Sphenoid cody). Malar. Superior maxillary. Palate. There are nine openings communicating with the orbit :—the optic, for the admission of the optic nerve and ophthalmic artery ; the sphe- noidal fissure, for the transmission of the third, fourth, the three branches of the ophthalmic division of the fifth and the sixth nerve, and the ophthalmic vein; the spheno-mazillary fissure, for the passage of the superior maxillary nerve and artery to the opening of entrance of the infra-orbital canal ; temporo-malar foramina—two or three small openings in the orbital process of the malar bone, for the passage of filaments of the orbital branch of the superior maxillary nerve ; an- terior and posterior ethmoidal foramina in the suture between the os planum and frontal bone, the former transmitting the nasal nerve and anterior ethmoidal artery, and the latter the posterior ethmoidal artery and vein ; the opening of the nasal duct ; and the supra-orbital notch or foramen, for the supra-orbital nerve and artery. NASAL FOSS, The nasal fossee are two irregular cavities, situate in the middle of the face, and extending from before backwards. They are bounded above by the nasal bones, ethmoid, and sphenoid; below by the palate processes of the superior maxillary and palate bones; éxternally by the 62 NASAL FOSSA. superior maxillary, lachrymal, inferior turbinated, ethmoid, palate, and internal pterygoid plate of the sphenoid; and the two fossz are sepa- rated by the vomer and the perpendicular lamella of the ethmoid. - These may be more clearly expressed in a tabular form :— Nasal bones. Ethmoid. Sphenoid. ae ty ta a _ a3 6 ; 7 4 Sas =) ads om o's + ° % a >, Sai 55 | Nasal fossa, | S| Nasal fossa. | BRSS Bm 5'2.8 - S°g 5 ho 3 EAS 5 SAE 2 FI & 5. 3S gee FI 5 2G 5 aa 8 a 5 a > Palate processes of superior maxillary. Palate processes of palate bone. Each nasal fossa is divided into three irregular longitudinal passages, or meatuses, by three processes of bone, which project from its outer wall, the superior, middle, and inferior turbinated bones; the supe- Fg. 31.* * A longitudinal section of the nasal fossee made immediately to the right of the middle line, and the bony septum removed in order to shew the external wall of the left fossa. 1. The frontal bone. 2, The nasal bone. 3. Thecrista ——- = TEETH.—CLASSIFICATION. 63 rior and middle turbinated bones being processes of the ethmoid, and the inferior a distinct bone of the face. The superior meatus occupies the superior and posterior part of each fossa; it is situated between the superior and middle turbinated bones, and has opening into it three foramina, viz, the opening of the posterior ethmoid cells, the opening of the sphenoid cells, and the spheno-palatine foramen. The middle meatus is the space between the middle and inferior turbinated bones; it also presents three foramina, the opening of the frontal sinuses, of the anterior ethmoid cells, and of the antrum. The largest of the three passages is the inferior meatus, which is the space between the inferior turbinated bone and the floor of the fossa; in it there are two foramina, the termination of the nasal duct, and one opening of the anterior palatine canal. The nasal fossze commence upon the face by a large irregular opening, the anterior nares, and terminate posteriorly in the two posterior nares. TEETH. Man is provided with two successions of teeth; the first are the teeth of childhood, they are called temporary, deciduous, or milk teeth ; the second continue until old age, and are named permanent. The permanent teeth are thirty-two in number, sixteen in each jaw; they are divisible into four classes,— incisors, of which there are four in each jaw, two central and two lateral; canine, two above and two below ; dicuspid, four above and four below; and molars, six above and six below. The temporary teeth are twenty in number; eight incisors, four ca- galli one of the ethmoid. The groove between 1 and 3 is the lateral bound- ary of the foramen ceecum. 4. The cribriform plate of the ethmoid. 5. Part of the sphenoidal cells: 6. The basilar portion of the sphenoid bone. Bones 2, 4, and 5, form the superior boundary of the nasal fossa. 7, 7. The articula- ting surface of the palatine process of the superior maxillary bone. The groove between 7, 7, is the lateral half of the incisive canal, and the dark aper- ture in the groove the inferior termination of the left naso-palatine canal. 8. The nasal spine. 9. The palatine process of the palate bone. a, The su- perior turbinated bone, marked by grooves and apertures for filaments of the olfactory nerve. 6. Thesuperior meatus. ¢, A probe passed into the posterior ethmoidal cells. d. The opening of the sphenoidal cells into the superior meatus. e. The spheno-palatine foramen. f. The middle turbinated bone. g, g- The middle meatus. A. A probe passed into the infundibular canal, leading from the frontal sinuses and anterior ethmoid cells; the triangular aperture immediately above the letter is the opening of the maxillary sinus, i. The inferior turbinated bone. 4k, k. The inferior meatus. 1,1. A probe assed up the nasal duct, shewing the direction of that canal. The anterior etters g, k, are placed on the superior maxillary bone, the posterior on the palate bone. m. The internal pterygoid plate. m. Its hamular process. o. The external pterygoid plate. p. The situation of the opening of the Eus- tachian tube. g. The posterior palatine foramina, the letter is placed on the hard palate. x. The roof of the left orbit. s. The optic foramen. ¢, The groove for the last turn of the internal carotid artery converted into a foramen by the development of an osseous communication between the anterior and middle clinoid processes. v. The sella turcica. 2. The posterior clinoid process. 64 STRUCTURE OF TEETH. nine, and eight molars. The temporary molars have four tubercles, and are succeeded by the permanent bicuspides, which have only two tubercles. Each tooth is divisible into a crown, which is the part apparent above the gum; a constricted portion around the base of the crown, the eck; and a root or fang, which is contained within the alveolus. The root is invested by periosteum, which lines the alveolus, and is then reflected upon the root of the tooth as far as its neck. The incisor teeth (cutting teeth) are named from presenting a sharp and cutting edge, formed at the expense of the posterior surface. The crown is flattened from before backwards, being somewhat convex in front and concave behind; the neck is considerably constricted, and the root compressed from side to side; at its apex is a small opening for the passage of the nerve and artery of the tooth. The canine teeth (cuspidati) follow the incisors in order from before backwards; two are situated in the upper jaw, one on each side, and two in the lower. The crown is larger than that of the incisors, con- vex before and concave behind, and tapering to a blunted point. The root is longer than that of all the other teeth, compressed at each side, and marked by a slight groove. The bicuspid teeth (bicuspidati, small molars), two on each side in each jaw, follow the canine, and are intermediate in size between them and the molars. The crown is compressed from before back- wards, and surmounted by two tubercles, one internal, the other ex- ternal ; the neck is oval; the root compressed, marked on each side by a deep groove, and bifid near its apex. The teeth of the upper jaw have a greater tendency to the division of their roots than those of the lower, and the posterior than the anterior pair. The molar teeth (multicuspidati, grinders), three on each side in each jaw, are the largest of the permanent set. The crown is quadri- lateral, and surmounted by four tubercles, the neck large and round, and the root divided into several fangs. In the upper jaw the first and second molar teeth have three roots, sometimes four, which are more or less widely separated from each other, two of the roots being external, the other internal. In the lower there are but two roots, which are anterior and posterior; they are flattened from behind for- wards, and grooved so as to mark a tendency to division. The third molars, or dentes sapientize, are smaller than the other two; they pre- sent three tubercles on the surface of the crown ; and the root is single and grooved, appearing to be made up of four or five fangs compressed together, or partially divided. In the lower jaw the fangs are fre- quently separated to some distance from each other, and much curved, so as to offer considerable resistance in the operation of extraction.* Structure.—The base of the crown of each tooth is hollowed in its interior into a small cavity which is continuous with a canal. passing through the middle of each fang. The cavity and canal, or canals, * See an excellent practical work, ‘‘On the Structure, Economy, and Pa- thology of the Teeth,’’ by Mr. Lintott. , - a ee re PT ee ae a ee ne ee ee STRUCTURE OF TEETH. 56 constitute the cavitas pulpze, and contain a soft cellulo-vascular organ, © the’ pulp, which receives its supply of vessels and nerves through the small opening at the apex of each root. Mr. Nasmyth, to whose inves- tigations science is so much indebted for our present knowledge of the intimate structure and development of the teeth, has observed with regard to the pulp, that it is composed of two different tissues, vascular and reticular, the former being an intricate web of minute vessels ter- minating in simple capillary loops, the latter a network of nucleated cells in which calcareous salts are gradually deposited, and which by a systematic continuance of that process are gradually converted into ivory. This process naturally takes place at the surface of the pulp, and as the pulp is thus robbed of its cells, new cells are produced by the capillary plexus to supply their place, and be in their turn simi- larly transformed. A tooth is composed of three distinct structures, ivory or tooth-bone, enamel, and a cortical substance or cementum. ‘The ivory consists of very minute, tapering, and branching fibres embedded in a dense homogeneous, interfibrous substance. The fibres commence by their larger ends at the walls of the cavitas pulp and pursue a radiating and serpentine course towards the periphery of the tooth, where they terminate in ramifications of extreme minuteness. These fibres, heretofore considered to be hollow tubuli, have been shewn by Mr. - Nasmyth to be rows of minute opake bodies, arranged in a linear series (baccated fibres, Nasmyth), to be, in fact, the nuclei of the ivory cells, the interfibrous substance being the rest of the cell filled with calcareous matter. In the natural state of the tooth all trace of the parietes or mode of connection of the cells is lost, but after steeping in weak acid the cellular network is perfectly distinct. The enamel forms a crust over the whole exposed surface of the crown of the tooth to the commencement of its ‘root ; it is thickest over the upper part of the crown, and becomes gradually thinner as it approaches the neck. It is composed of minute hexagonal crystalline fibres, resting by one extremity against the surface of the ivory, and constituting by the other the free surface of the crown. The fibres examined on the face of a longitudinal section have a waving arrange- ment, and consist, like those of ivory, of cells connected by their sur- faces and ends and filled with calcareous substance. When the latter is removed by weak acid the enamel presents a delicate cellular net- work of animal matter. The cortical substance, or cementum, (substantia ostoidea,) forms a thin coating over the root of the tooth, from the termination of the enamel to the opening in the apex of the fang. In structure it is analogous to bone, and is characterized by the presence of numerous ealcigerous cells and tubuli. The cementum increases in thickness with the advance of age, and gives rise to those exostosed appear- ances occasionally seen in the teeth of very old persons, or in those who have taken much mercury. In old age the cavitas pulpz is often found filled up and obliterated by osseous substance analogous to the F 66 DEVELOPMENT OF TEETH. cementum. Mr. Nasmyth has shewn that this, like the other struc- tures composing a tooth, is formed of cells having a reticular arrange- -ment. Development.—The development of the teeth in the human subject has been successfully investigated by Mr. Goodsir, to whose interest- ing researches I am indebted for the following narrative :*— The inquiries of Mr. Goodsir commenced as early as the sixth week after conception, in an embryo, which measured seven lines and a half in length and weighed fifteen grains. At this early period each upper jaw presents two semicircular folds around its circumference ; the most external is the true lip; the internal, the rudiment of the palate ; and between these is a deep groove, lined by the common mucous membrane of the mouth. A little later, a ridge is developed from the floor of this groove in a direction from behind forwards, this is the rudiment of the external alveolus; and the arrangement of the appear- ances from without inwards at this period is the following :— Most externally and forming the boundary of the mouth, is the dip; next we find a deep groove, which separates the lip from the future jaw; then comes the eaternal alveolar ridge; fourthly, another groove, in which the germs of the teeth are developed, the primitive dental groove ; fifthly, a rudiment of the internal alveolar ridge; and, sixthly, the rudiment of the future palate bounding the whole in- ternally. At the seventh week the germ of the first deciduous molar of the upper jaw has made its appearance, in the form of a “ simple, free, granular papilla”? of the mucous membrane, projecting from the floor of the primitive dental groove; at the eighth week, the papilla of the canine tooth is developed ; at the ninth week, the papilla of the four incisors (the middle preceding the lateral) appear; and at the tenth week the papilla of the second molar is seen behind the anterior molar in the primitive dental groove. So that at this early period, viz. the tenth week, the papille or germs of the whole ten deciduous teeth of the upper jaw are quite distinct. Those of the lower jaw are a little more tardy; the papilla of the first molar is merely a slight bulging at the seventh week, and the tenth papilla is not apparent until the eleventh week. From about the eighth week the primitive dental groove becomes contracted before and behind the first deciduous molar, and laminz of the mucous membrane are developed around the other papilla, which increase in growth and enclose the papille in follicles with open mouths. At the tenth week the follicle of the first molar is com- pleted, then that of the canine; during the eleventh and twelfth weeks the follicles of the incisors succeed, and at the thirteenth week the follicle of the posterior deciduous molar. During the thirteenth week the papille undergo an alteration of form, and assume the shape of the teeth they are intended to repre- * “On the Origin and Development of the Pulps and Sacs of the Human Teeth,’ by John Goodsir, jun. in the Edinburgh Medical and Surgical Journal, January 1839. DEVELOPMENT OF TEETH. 67 sent. And at the same time small membranous processes are de- veloped from the mouths of the follicles ; these processes are intended to serve the purpose of opercula to the follicles, and they correspond in shape with the form of the crowns of the appertaining teeth. To the follicles of the incisor teeth there are two opercula; to the canine, three ; and to the molars a number relative to the number of their tubercles, either four or five. During the fourteenth and fifteenth weeks the opercula have completely closed the follicles, so as to convert them into dental sacs, and at the same time the papille have become pulps. The deep portion of the primitive dental groove, viz. that which con- tains the dental sacs of the deciduous teeth, being thus closed in, the remaining portion, that which is nearer the surface of the gum, is still left open, and to this Mr. Goodsir has given the title of secondary dental groove ; as it serves for the development of all the permanent teeth, with the exception of the anterior molars. During the four- teenth and fifteenth weeks small lunated inflections of the mucous membrane are formed, immediately to the inner side of the closing opercula of the deciduous dental follicles, commencing behind the incisors and proceeding onwards through the rest; these are the rudiments of the follicles or cavities of reserve of the four permanent incisors, two permanent canines, and the four bicuspides. As the secondary dental groove gradually closes, these follicular inflections of the mucous membrane are converted into closed cavities of reserve, which recede from the surface of the gum and lie immediately to the inner side and in close contact with the dental sacs of the deciduous teeth, being enclosed in their submucous cellular tissue. At-about the fifth month the anterior of these cavities of reserve dilate at their distal extremities, and a fold or papilla projects into their fundus, constituting the rudiment of the germ of the permanent tooth ; at the same time two small opercular folds are produced at their proximal or small extremities, and convert them into true dental sacs. During the fifth month the posterior part of the primitive dental groove behind the sac of the last deciduous tooth has remained open, and in it has developed the papilla and follicle of the first permanent molar. Upon the closure of this follicle by its opercula, the secondary dental groove upon the summit of its crown forms a large cavity of reserve, lying in contact with the dental sac upon the one side and with the gum upon the superiicial side. At this period the deciduous teeth, and the sacs of the ten anterior permanent teeth, increase so much in size, without a corresponding lengthening of the jaws, that the first permanent molars are gradually pressed backwards and upwards into the maxillary tuberosity in the upper jaw, and into the base of the coronoid process of the lower jaw; a position which they occupy at the eighth and ninth months of feetal life. In the infant of seven or eight months the jaws have grown in length, and the first permanent molar returns to its proper position in the dental range. The cavity of reserve, which has been previously elongated by the 68 GROWTH OF TEETH. upward movement of the first permanent molar, now dilates into the cavity which that tooth has just quitted; a papilla is developed from its fundus, the cavity becomes constricted, and the dental sac of the second molar tooth is formed, still leaving a portion of the great cavity of reserve in connection with the superficial side of the sac. As the jaws continue to grow in length, the second permanent dental sac descends from its elevated position and advances forwards into the dental range, following the same curve with the first permanent molar. The remainder of the cavity of reserve, already lengthened ‘backwards by the previous position of the second molar, again dilates for the last time, developes a papilla and sac in the same manner with the preceding, and forms the third permanent molar or wisdom tooth, which at the age of nineteen or twenty, upon the increased growth of the jaw, follows the course of the first and second molars into the dental range. From a consideration of the foregoing phenomena, Mr. Goodsir has divided the process of dentition into three natural stages:—1. folli- cular; 2. saccular; 3. eruptive. The first, or follicular stage, he makes to include all the changes which take place from the first appearance of the dental groove and papillz to the closure of their follicles; occupying a period which extends from the sixth week to the fourth or fifth month of intra-uterine existence. The second, or saccular stage, comprises the period when the follicles are shut sacs, and the included papillz pulps; it commences at the fourth and fifth months of intra-uterine existence, and terminates for the median incisors, at the seventh or eighth month of infantile life; and for the wisdom teeth at about the twenty-first year. The third, or eruptive stage, includes the completion of the teeth, the eruption and shedding of the temporary set, the eruption of the permanent, and the necessary changes in the alveolar processes. It extends from the seventh month till the twenty-first year. “The anterior permanent molar,” says Mr. Goodsir, “is the most remarkable tooth in man, as it forms a transition between the milk and the permanent set.” If considered anatomically, 7. e. in its de- velopment from the primitive dental groove, by a papilla and follicle, “it is decidedly a milk tooth;” if physiologically, “as the most efficient grinder in the adult mouth, we must consider it a permanent tooth.” “It is a curious circumstance, and one which will readily suggest itself to the surgeon, that laying out of view the wisdom teeth, which sometimes decay at an early period from other causes, the anterior molars are the permanent teeth which most frequently give way first, and in the most symmetrical manner and at the same time, and frequently before the milk set.” Growth of Teeth—Immediately that the dental follicles have been closed by their opercula, the pulps become moulded into the form of the future teeth; and the bases of the molars divided into two or three portions representing the future fangs. The dental sac is com- posed of two layers, an internal or vascular layer, which was originally 6132) Dial k's eet heee en” TEETH.—ERUPTION. 69 a part of the mucous surface of the mouth, and a cellulo-fibrous layer, analogous to the corium of the mucous membrane. Upon the forma- tion of this sac by the closure of the follicle, the mucous membrane resembles a serous membrane in being a shut sac, and may be con- sidered as consisting of a tunica propria, which invests the pulp; and a tunica reflexa, which is adherent by its outer surface with the structures in the jaw, and by the inner surface is free, being separated from the pulp by an intervening cavity. As soon as the moulding of the pulp has commenced, this cavity increases and becomes filled with a gelatinous granular substance, the enamel organ, which is adherent to the whole internal surface of the tunica reflexa, but not to the tunica propria and pulp. At the same period, viz. during the fourth or fifth month, a thin lamina of ivory is formed by the pulp, and occupies its most prominent point: if the tooth be incisor or canine, the newly formed layer has the figure of a small hollow cone; if molar, there will be four or five small cones corresponding with the number of tubercles on its crown. These cones are united by the formation of additional layers, the pulp becomes gradually sur- rounded and diminishes in size, evolving fresh layers during its - retreat into the jaws until the entire tooth with its fangs is completed, and the small cavitas pulpz of the perfect tooth alone remains, com- municating through the opening in the apex of each fang with the . dental vessels and nerves. The number of roots appears to depend upon the number of nervous filaments sent to each pulp. When the formation of the ivory has commenced, the enamel organ becomes transformed into a laminated tissue, corresponding with the direction of the fibres of the enamel, and the crystalline substance of the enamel is secreted into its meshes by the vascular lining of the sac. The cementum appears to be formed at a later period of life, either by a deposition of osseous substance by that portion of the dental sac, which continues to enclose the fang, and acts as its periosteum, or by the conversion of that membrane itself into bone ; the former supposi- tion is the more probable. The formation of ivory commences in the first permanent molar pre- viously to birth. Eruption. — When the crown of the tooth has been formed and coated with enamel, and the fang has grown to the bottom of its socket by the progressive lengthening of the pulp, the formation of ivory, and the adhesion of the ivory to the contiguous portion of the sac, the pressure of the socket causes the reflected portion of the sac and the edge of the tooth to approach, and the latter to pass through the gum. The sac has thereby resumed * its original follicular condition, and has become continuous with the mucous membrane of the mouth. The opened sac now begins to shorten more rapidly than the fang lengthens, and the tooth is quickly drawn upwards by the contraction, leaving a * Mr. Nasymth is of opinion that it is ‘‘ by a process of absorption, and not of disruption, that the tooth is emancipated.’’? Medico-chirurgical Transac- tions. 1839. 70 OS HYOIDES. space between the extremity of the unfinished root and the bottom of the socket, in which the growth and completion of the fang is more speedily effected. During the changes which have here heen described as taking place among the dental sacs contained within the jaws, the septa between the sacs, which at first were composed of spongy tissue, soon became fibrous, and were afterwards formed of bone, which was developed from the surface and proceeded by degrees more deeply into the jaws, to constitute the alveoli. The sacs of the ten anterior permanent teeth, at first enclosed in the submucous cellular tissue of the deciduous dental sacs, and received during their growth into crypts situated behind the deciduous teeth advanced by degrees beneath the fangs of those teeth, and became separated from them by distinct osseous al- veoli. The necks of the sacs of the permanent teeth, by which they originally communicated with the mucous lining of the secondary groove, still exist, in the form of minute obliterated cords, separated from the deciduous teeth by their alveolus, but communicating through @ minute osseous canal with the fibrous tissue of the palate, im-. mediately behind the corresponding deciduous teeth. ‘* These cords and foramina are not obliterated in the child,” says Mr. Goodsir, ** either because the cords are to become useful as * gubernacula’ and the canals as ‘ itinera dentium ;’ or, much more probably, in virtue of a law, which appears to be a general one in the development of animal bodies, viz. that parts, or organs, which have once acted an important part, however atrophied they may afterwards become, yet never alto- gether disappear, so long as they do not interfere with other parts or Junctions.” Succession.—The periods of appearance of the teeth are extremely irregular ; it is necessary, therefore, to have recourse to an average, which, for the temporary teeth, may be stated as follows, the teeth of the lower jaw preceding those of the upper by a short interval :— 7th month, two middle incisors. 18th month, canine. 9th month, two lateral incisors. 24th month, two last molares, 12th month, first molares. The periods for the permanent teeth are, 64 year, first molares. 10th year, second bicuspides. 7th year, two middle incisors. 11th to 12th year, canine. 8th year, two lateral incisors. 12th to. 13th year, second molares. 9th year, first bicuspides. 17th to 21st year, last molares. OS HYOIDES, The os hyoides forms the second arch developed from the cranium, and gives support to the tongue, and attachment to numerous muscles in the neck. It is named from its resemblance to the Greek letter Us and consists of a central portion or body, of two larger cornua, which —— SS STERNUM. Pa | project backwards from the body ; and two lesser cornua, which ascend from the angles of union between the body and the greater cornua. The body is somewhat quadrila- teral, rough and convex on its ante- ro-superior surface, by which it gives attachment to muscles; con- cave and smooth on the postero-in- ferior surface, by which it lies in contact with the thyro-hyoidean membrane. The greater cornua are flattened from above downwards, and terminated posteriorly by a tubercle ; and the lesser cornua, conical in form, give attachment to the stylo-hyoid ligaments. In early age and in the adult, the cor- nua are connected with the body by cartilaginous surfaces and liga- mentous fibres; but in old age they become united by bone. Development.—By five centres, one for the body, and one for each cornu. Ossification commences in the greater cornua during the last month of fcetal life, and in the lesser cornua and body soon after birth. Attachment of Muscles.—To eleven pairs; sterno-hyoid, thyro-hyoid, omo-hyoid, pulley of the digastricus, stylo-hyoid, mylo-hyoid, genio- hyoid, genio-hyo-glossus, hyo-glossus, lingualis, and middle constrictor of the pharynx. It also gives attachment to the stylo-hyoid, thyro- hyoid, and hyo-epiglottic ligaments, and to the tliyro-hyoidean mem- brane. THORAX AND UPPER EXTREMITY. The bones of the thorax are the sternum and ribs; and, of the upper extremity, the clavicle, scapula, humerus, ape and radius, bones of the carpus, metacarpus, and phalanges. Srernum.—The sternum (fig. 33) is situated in the middle line of the front of the chest, and is oblique in direction, the superior end lying within a few inches of the vertebral column, and the inferior being projected forwards so as to be placed at a considerable distance from the spine. The bone is flat or slightly concave in front, and marked by five transverse lines which indicate its original subdivision into six pieces. It is convex behind, broad and thick above, flattened and pointed below, and-is divisible in the adult into three pieces, superior, middle, and inferior. The superior piece or manubrium is nearly quadrilateral ; it is broad and thick above, where it presents a concave border (incisura semi- * The os hyoides seen from before. 1. The antero-superior, or convex side of the body. 2. The great cornu of the left side. 3. The lesser ‘cornu of the same side. The cornua were ossified to the body of the bone in the specimen from which this figure was drawn. 72 RIBS. - lunaris), and narrow at its junction with the middle piece. At each superior angle is a deep articular depression (incisura clavicularis) for the clavicle, and on either side two notches, for the articulation of the cartilage of the first rib, and one half of the second. The middie piece or body, considerably longer than the superior, is broad in the middle, and somewhat narrower at each extremity. It presents at either side six articular notches, for the lower half of the second rib, the four next ribs, and the upper half of the seventh. This piece is sometimes perforated by an opening of various magnitude resulting from arrest of development. The inferior piece (ensiform or xiphoid cartilage) is the smallest of the three, often merely cartilaginous, and very various in appearance, being sometimes pointed, at other times broad and thin, and at other times again, perforated by a round hole, or bifid. It presents a notch at each side for the articulation of the lower half of the cartilage of the seventh rib. Development.—By a variable number of centres, generally ten, namely, two for the manubrium; one (sometimes two) for the first piece of the body, two for each of the remaining pieces, and one for the ensiform cartilage. Ossification commences towards the end of the fifth month in the manubrium, the two pieces for this part being placed one above the other. At about the same time the centres for the first and second pieces of the body are apparent; the centres for the third piece of the body appear a few months later, and those for the fourth. piece soon after birth. The osseous centre for the ensiform cartilage, is so variable in its advent, that it may be present at any period between the third and eighteenth year. The double centres for the body of the sternum are disposed side by side in pairs, and it is the irregular union of these pairs in the last three pieces of the body that gives rise to the large aperture occasionally seen in the sternum towards its lower part. Union of the pieces of the sternum com- mences from below and proceeds upwards; the fourth and the third unite at about puberty, the third and the second between twenty and twenty-five, and the second and the first between twenty-five and thirty. The ensiform appendix becomes joined to the body of the sternum at forty or fifty years; and the manubrium to the body only in very old age. Two small pisiform pieces have been described by Beclard and Breschet, as being situated upon and somewhat behind each extremity of the incisura semilunaris of the upper border of the manubrium. These pre-sternal or supra-sternal pieces which are by no means constant, appear at about the thirty-fifth year. Beclard considers them to be the analogue of the fourchette of birds, and Breschet as the sternal ends of the cervical rib. Articulations.—W ith sixteen bones ; viz. with the clavicle and the seven true ribs, at each side. Attachment of Muscles.—To nine pairs and one single muscle ; viz. to the pectoralis major, sterno-mastoid, sterno-hyoid, sterno-thyroid, a RIBS.—TRUE AND FALSE. 73 triangularis sterni, aponeurosis of the obliquus externus, internus, and transversalis muscles, rectus, and diaphragm. Riss.—The ribs are twelve in number at each side; the first seven are connected with the sternum, and hence named sternal or true ribs; the remaining five are the asternal or false ribs; and the last two shorter than the rest, and free at their extremities, are the floating ribs. The ribs increase in length from the first to the eighth, whence they again diminish to the twelfth; in breadth they diminish gradually from the first to the last, and with the exception of the last two are broader at the anterior than at the posterior end. The first rib is horizontal in its direction; ali the rest are oblique, so that the ante- rior extremity falls considerably below the posterior. Each rib pre- sents an external and internal surface, a superior and inferior border, * An anterior view of the thorax. 1. The superior piece of the sternum 2. The middle piece. 3%. The inferior piece, or ensiform cartilage. 4. The first dorsal vertebra. 5. The last dorsal vertebra. 6. The first rib. 7. Its head _ 8. Its neck, resting against the transverse process of the first dorsal vertebra. 9. Its tubercle. 10. The seventh or last true rib. 11. The costal cartilages of the true ribs. 12. The last two false ribs or floating ribs. 13. The groove along the lower border of the rib. 74 RIBS.— TRUE AND FALSE. and two extremities; it is curved to correspond with the arch of the thorax, and twisted upon itself, so that, when laid on its side, one end is tilted up, while the other rests upon the surface. The eternal surface is convex, and marked by the attachment of muscles; the internal is flat, and corresponds with the pleura; the superior border is rounded ; and the inferior sharp and grooved upon its inner side, for the attachment of the intercostal muscles.* Near its vertebral extremity, the rib is suddenly bent upon itself; and opposite the bend, upon the external surface, is a rough oblique ridge, which gives attachment to a tendon of the sacro-lumbalis muscle, and is called the angle. The distance between the vertebral extremity and the angle increases gradually, from the second to the eleventh rib. Beyond the angle is a rough elevation, the tubercle; and immediately at the base and under side of the tubercle a smooth surface for articulation with the extremity of the transverse process of the corre- sponding vertebra. The vertebral end of the rib is somewhat ex- panded, and is termed the head, and that portion between the head and the tubercle is the neck. On the extremity of the head is an oval smooth surface divided by a transeverse ridge into two facets for articulation with two contiguous vertebra. The posterior sur- face of the neck is rough, for the attachment of the middle costo- transverse ligament; and upon its upper border is a crest, which gives attachment to the anterior costo-transverse ligament. The sternal extremity is flattened, and presents an oval depression, into which the costal cartilage is received. The ribs that demand especial consideration are the first, tenth, eleventh, and twelfth. The first is the shortest rib; it is broad and flat, and placed horizon- tally at the upper part of the thorax, the surfaces looking upwards and downwards, in place of forwards and backwards as in the other ribs. At about the anterior third of the upper surface of the bone, and near its internal border, is a tubercle which gives attachment to the scalenus anticus muscle, and immediately before and behind this tubercle, a shallow oblique groove, the former for the subclavian vein, and the latter for the subclavian artery. Near the posterior extremity of the bone is a thick and prominent tubercle, with a smooth articular sur- face for the transverse process of the first dorsal vertebra. There is no angle. Beyond the tuberosity is a narrow constricted neck; and at the extremity, a head, presenting a single articular surface. The second rib approaches in sonie of its characters to the first. The ¢enth rib has a single articular surface on its head. The eleventh and twelfth have each a single articular surface on the head, no neck or tubercle, and are pointed at the free extremity. The eleventh has a slight ridge, representing the angle, and a shallow groove on the lower border; the twelfth has neither. * This groove is commonly described as supporting the intercostal art vein and nerve, but this is not the case. - = =r - COSTAL CARTILAGES. 75 Costa CartinaGEes.—The costal cartilages serve to prolong the ribs forwards to the anterior part of the chest, and contribute mainly to the elasticity of the thorax. They are broad at their attachment to the ribs, and taper slightly towards the opposite extremity; they diminish gradually in breadth from the first to the last ; in length they increase from the first to the seventh, and then decrease to the last. The cartilages of the first two ribs are horizontal in direction, the rest incline more and more upwards. In advanced age the costal cartilages are mere or less converted into bone, this change taking place earlier in the male than in the female. The first seven cartilages articulate with the sternum; the three next, with the lower border of the cartilage immediately preceding, while the last two lie free between the abdominal muscles. All the cartilages of the false ribs terminate by pointed extremities. Development.—The ribs are developed by three centres; one for the central part, one for the head, and one for the tubercle. The last two have no centre for the tubercle. Ossification commences in the body somewhat before its appearance in the vertebra ; the epiphysal centres for the head and tubercle appear between sixteen and twenty, and are consolidated with the rest of the bone at twenty-five. Articulations.—Each rib articulates with two vertebra, and one costal cartilage, with the exception of the first, tenth, eleventh, and twelfth, which articulate each with a single vertebra only. Attachment of Muscles.—To the ribs and their cartilages are attach- ed twenty-two pairs, and one single muscle. To the cartilages, the subclavius, sterno-thyroid, pectoralis major, internal oblique, rectus, transyersalis, diaphragm, triangularis sterni, internal and external in- tercostals. To the ribs, the intercostal muscles, scalenus anticus, scalenus posticus, pectoralis minor, serratus magnus, obliquus externus, obliquus internus, latissimus dorsi, quadratus lumborum, serratus posti- cus superior, serratus posticus inferior, sacro-lumbalis, longissimus dorsi, cervicalis ascendens, levatores costarum, transversalis, and diaphragm. Craviciz.—The clavicle is a long bone shaped like the italic letter J; and extended across the upper part of the side of the chest from the upper piece of the sternum to the point of the shoulder, where it arti- culates with the scapula. In position it is very slightly oblique, the sternal end being somewhat lower and more anterior than the scapular, and the curves are so disposed that at the sternal end the convexity, and at the scapular the concavity, is directed forwards. The sternal half of the bone is rounded or irregularly quadrilateral, and terminates in a broad articular surface. The scapular half is flattened from above downwards, and broad at its extremity, the articular surface occupying only part of its extent. The upper surface is smooth and convex, and partly subcutaneous; while the under surface is rough and depressed, for the insertion of the subclavius muscle. At the sternal extremity of the under surface is a very rough prominence, which gives attach- ment to the rhomboid ligament ; and at the other extremity a rough 76 SCAPULA. tubercle and ridge, for the coraco-clavicular ligament. The opening for the nutritious vessels is seen upon the under surface of the bone. Development.—By two centres; one for the shaft and one for the sternal extremity ; the former appearing before any other bone of the skeleton, the latter between fifteen and eighteen. Articulations.— With the sternum and scapula. Attachment of Muscles.—To sia; the sterno-mastoid, trapezius, pec- toralis major, deltoid, subclavius, and sterno-hyoid. . ScapuLa.—The scapula is a flat triangular bone, situated upon the posterior aspect and side of the thorax occupying the space from the second to the seventh rib. It is divisible into an anterior and poste- rior surface, superior, inferior, and posterior border, anterior, superior, and inferior angle, and processes. The anterior surface, or subscapular fossa, is concave and irregular, and marked by several oblique ridges which have a direction upwards and outwards. The whole concavity is occupied by the subscapularis muscle, with the exception of a small triangular portion near the supe- rior angle. The posterior surface or dorsum is convex, and unequally divided into two portions by the spine; that portion above the spine is the supra-spinous fossa; and that below, the infra-spinous fossa. The superior border is the shortest of the three; it is thin and con- cave, and terminated at one extremity by the superior angle, and at the other by the coracoid process. At its inner termination, and formed partly by the base of the coracoid process, is the supra-scapular notch, for the transmission of the supra-scapular nerve. The inferior or aaillary border is thick, and marked by several grooves and depressions; it terminates superiorly at the glenoid cavity, and inferiorly at the inferior angle. Immediately below the glenoid cavity is a rough ridge, which gives origin to the long head of the triceps muscle. Upon the posterior surface of the border is-a de- pression for the teres minor; and upon its anterior surface a deeper groove for the teres major: near the inferior angle is a projecting lip, which increases the surface of origin of the latter muscle. The posterior border or base, the longest of the three, is turned to- wards the vertebral column. It is intermediate in thickness between the superior and inferior, and convex, being considerably inflected out- wards towards the superior angle. The anterior angle is the thickest part of the bone, and forms the head of the scapula; it is immediately surrounded by a constricted portion, the neck. The head presents a shallow pyriform articular sur- face, the glenoid cavity, having the pointed extremity upwards; and at its apex is a rough depression, which gives attachment to the long tendon of the biceps. The superior angle is thin and pointed. The inferior angle is thick, and smooth upon the external surface for the origin of the teres major and for a large bursa over which the upper border of the latissimus dorsi muscle plays. The spine of the scapula, triangular in form, crosses the upper part of SCAPULA- 77 dorsum; it commences at the posterior border by a smooth triangular surface over which the trapezius glides upon a bursa, and terminates at the point of the shoul- der in the acromion process. ; The upper border of the. Vids ae" spine is rough and subcu- taneous, and gives attach- ment by two projecting lips to the trapezius and del- toid muscles; the surfaces of the spine enter into the . formation of the supra and infra-spinous fosse. The nutritious foramina of the scapula are situated in the base of the spine. The acromion is some- what triangular and flat- tened from above down- wards; it overhangs the glenoid cavity, the upper surface being rough and - subcutaneous, the lower smooth and corresponding with the shoulder-joint. Near its extremity, upon the anterior border, is an oval articular surface, for the end of the clavicle. The coracoid process is a thick, round, and curved process of bone, arising from the upper part of the neck of the scapula, and overarching the glenoid cavity. It is about two inches in length and very strong ; it gives attachment to several ligaments and muscles. Development.— By six centres; one for the body, one for the coracoid process, two for the acromion, one for the inferior angle, and one for the posterior border. The ossific centre for the body appears in the infra-spinous fossa at about the same time with the ossification of the vertebra; for the coracoid process during the first year; the acro- mion process at puberty; the inferior angle in the fifteenth year; and the posterior border at seventeen or eighteen. Union between the * A posterior view of the scapula. 1. The supra-spinous fossa. 2. The infra-spinous fossa. 3. The superior border. 4. The supra-scapular notch. 5. The anterior or axillary border. 6. The head of the scapula and glenoid cavity. 7. Theinferior angle. 8. The neck of the scapula, the ridge opposite the number gives origin to the long head of the triceps. 9. The posterior border or base of the scapula. 10. The spine. 11. The triangular smooth surface, over which the tendon of the trapezius glides. 12. The acromion process. 13. One of the nutritious foramina. 14. The coracoid process, 78 HUMERUS. coracoid process and body takes place during the fifteenth year; the bone is not complete till manhood. Articulations.— With the clavicle and humerus. Attachment of Muscles.—To sixteen; by its anterior surface to the subscapularis; posterior surface, supra-spinatus and infra-spinatus; superior border, omo-hyoid; posterior border, levator anguli scapulze, rhomboideus minor, rhomboideus major, and serratus magnus; anterior border, long head of the triceps, teres minor, and teres major; upper angle of the glenoid cavity, to the long tendon of the biceps; spine and acromion, to the trapezius and deltoid; coracoid process, to the pectoralis minor, short head of the biceps, and coraco-brachialis. The ligaments attached to the coracoid process are, the coracoid, coraco-clavicular, and coraco-humeral, and the costo-coracoid mem- brane. Humervus.—The humerus is a long bone divisible into a shaft and two extremities. The superior extremity presents a rounded head; a constriction im- mediately around the base of the head, the neck ; a greater and a lesser tuberosity. The greater tuberosity is situated most externally, and is separated from the lesser by a vertical furrow, the Jicipital groove, which lodges the long tendon of the biceps. The edges of this groove below the head of the bone are raised and rough, and are called the anterior and posterior bicipital ridge; the former serves for the in- sertion of the pectoralis major muscle, and the latter of the latissimus dorsi and teres major. , The constriction of the bone below the tuberosities is the surgical neck, and is so named, in contradistinction to the true neck, from be- ing the seat of the accident called by surgical writers fracture of the neck of the humerus. The shaft of the bone is prismoid at its upper part, and flattened from before backwards below. Upon its outer side, at about its middle, is a rough triangular eminence, which gives insertion to the deltoid ; and immediately on each side of this eminence is a smooth depression, corresponding with the two heads of the brachialis anticus. Upon the inner side of the middle of the shaft is a ridge, for the at- tachment of the coraco-brachialis muscle ; and behind, an oblique and shallow groove, which lodges the musculo-spiral nerve and superior profunda artery. The foramen for the medullary vessels is situated upon the inner surface of the shaft of the bone a little below the coraco-brachial ridge ; it is directed downwards. The lower eatremity is flattened from before backwards, and is ter- minated inferiorly by a long articular surface, divided into two parts by an elevated ridge. The external portion of the articular surface is a rounded protuberance, eminentia capitata, which articulates with the cup-shaped depression on the head of the radius ; the internal portion is a concave and pulley-like surface, ¢rochlea, which articulates with the ulna. Projecting beyond the articular surface on each side are ~ HUMERUS. 79 the eaternal and internal condyle, the latter being considerably the longer ; and running upwards from the condyles upon the borders of the bone are the condyloid ridges, of which the external is the most prominent. Immediately in front of the trochlea is a small depression for receiving the coronoid process of the ulna during flexion of the fore-arm ; and immedi- ately behind it a large and deep fossa, for con- taining the olecranon process in extension. ment. — By seven centres ; one for the shaft, one for the head, one for the tu- berosities, one for the eminentia capitata, one for the trochlea, and one for each condyle, the internal preceding the external. Ossifica- tion commences in the diaphysis of the hu- merus soon after-the clavicle ; in the head and tuberosities, during the second and third years of infantile life; in the eminentia capitata and trochlea during the third and sixth years ; and in the condyles during the twelfth and fifteenth. The entire bone is consolidated at twenty. Articulutions.—With the glenoid cavity of the scapula, and with the ulna and radius. Attachment of Muscles.—To twenty-four ; by the greater tuberosity to the supra-spinatus, in- fra-spinatus, and teres minor ; lesser tuberosity, subscapularis ; anterior bicipital ridge, pectoralis major; posterior bicipital ridge and groove, teres major and latissimus dorsi ; shaft, external and internal heads of the triceps, deltoid, coraco- brachialis, and brachialis anticus ; external con- dyloid ridge and condyle (condylus extensorius), extensors and supinators of the fore-arm, viz. supinator longus, extensor carpi radialis lon- gior, extensor carpi radialis brevior, extensor communis digitorum, extensor minimi digiti, extensor carpi ulnaris, anconeus, and supinator brevis ; internal con- dyle (condylus flexorius), flexors and one pronator, viz. pronator radii teres, flexor carpi radialis, paimaris longus, flexor sublimis digitorum, and flexor carpi ulnaris. * The humerus of the right side; its anterior surface. 1. The shaft of the bone. 2. The head. 3. The anatomical neck. 4. The greater tuberosity. 5. The lesser tuberosity. 6. The bicipital groove. 7. The anterior bicipital ridge. 8 The posterior bicipital ridge. 9. The rough surface into which the deltoid is inserted. 10, The nutritious foramen. 11. The eminentia capitata. 12. The trochlea. 13 The external condyle. 14 The internal condyle. 15. The external condyloid ridge. 16. The internal condyloid ridge. 17. The fossa for the coronoid process of the ulna. 80 ULNA. Uxina.—The ulna is a long bone, divisible into a shaft and two extremities. The upper extremity is large, and forms principally the articulation of the elbow; while the lower extremity is small, and excluded from the wrist-joint by an inter-articular fibro-cartilage. The superior extremity presents a semilunar concavity of large size, the greater sigmoid notch, for articulation with the humerus; and upon the outer side a lesser sigmoid notch, which articulates with the head of the radius. Bounding the greater sigmoid notch posteriorly is the olecranon process ; and, overhanging it in front, a pointed eminence with a rough triangular base, the coronoid process. Behind the lesser sigmoid notch, and extending downwards on the side of the olecranon, is a triangular uneven surface, for the anconeus muscle ; and upon the posterior surface of the olecranon a smooth triangular surface, which is subcutaneous. The shaft is prismoid in form, and presents three surfaces, anterior, posterior, and internal; and three borders. The anterior surface is occupied by the flexor profundus digitorum for the upper three-fourths of its extent ; and below by a depression, for the pro- nator quadratus muscle. A little above its middle is the nutritious foramen, which is directed upwards. Upon the posterior surface at the upper part of the bone is the triangular uneven depression for the anconeus muscle, bounded inferiorly by an oblique ridge which runs downwards from the posterior extremity of the lesser sigmoid notch. Below the ridge the surface is marked into several grooves, for the at- tachment of the extensor ossis metacarpi, extensor secundi internodii, and extensor indicis muscle. The internal surface is covered in for the the greater part of its extent by the flexor profundus digitorum. The anterior border is rounded, and gives origin by its lower fourth to the pronator quadratus ; the posterior is more prominent, and affords at- tachment to the flexor carpi ulnaris and extensor carpi ulnaris. At its upper extremity it expands into the triangular subcutaneous sur- face of the olecranon. The eaternal or radial border is sharp and pro- minent, for the attachment of the interosseous membrane. The lower eatremity terminates in a small rounded head, capitulum uln@, from the side of which projects the styloid process. The latter presents a deep notch at its base for the attachment of the apex of the triangular interarticular cartilage, and by its point gives attachment to the internal lateral ligament. Upon the posterior surface of the head is a groove, for the tendon of the extensor carpi ulnaris ; and upon the side opposite to the styloid process a smooth surface, for articulation with the side of the radius. Development.—By three centres ; one for the shaft, one for the in- ferior extremity, and one for the olecranon. Ossification commences in the ulna shortly after the humerus and radius ; the two ends of the bone are cartilaginous at birth. The centre for the lower end appears at about the fifth, and that for the olecranon about the seventh year. The bone is completed at about the twentieth year. Articulations.—W ith two bones ; the humerus and radius ; it is se- ee ee SN ae ee ee ae ee ee ee See RADIUS, 81 parated from the cuneiform bone of the carpus by the triangular inter- articular cartilage. Attachment of Muscles.—To twelve ; by the olecranon, to the triceps extensor cubiti, one head of the flexor carpi ulnaris, and the an- coneus; by the coronoid process, to the brachialis anticus, pronator radii teres, flexor sublimis digitorum, and flexor profundus digitorum; by the shaft, to Fig. 36.* the flexor profundus digitorum, flexor carpi ulnaris, pronator quadratus, anconeus, extensor carpi ulnaris, extensor ossis metacarpi pollicis, extensor secundi internodii pollicis, and ex- tensor indicis. Rapivus.—The radius is the rotatory bone of the fore-arm ; it is divisible into a shaft and two extremities: unlike the ulna, its upper extremity is small, and merely accessory to the . formation of the elbow-joint ; while the lower extremity is large, and forms almost solely the joint of the wrist. The superior extremity presents a rounded head, depressed upon its upper surface into a shallow cup. Around the margin of the head is a smooth articular surface, which is broad on the inner side, where it articulates with the lesser sigmoid notch of the ulna, and narrow in the rest of its circumference, to play in the orbicular ligament. Beneath the head is a round constricted neck ; and beneath the neck, on its internal aspect, a prominent process, the tuberosity. The surface of the tuberosity is partly smooth, and partly rough ; rough below, where it receives the attachment of the tendon of the biceps ; and smooth above, where a bursa is interposed between the tendon and the bone. The shaft of the bone is prismoid, and presents three surfaces. The anterior surface is somewhat concave superiorly, where it lodges the flexor longus pollicis ; and flat below, where it supports the pro- nator quadratus. At about the upper third of this surface is the nu- tritious foramen, which is directed upwards. Ths posterior surface is * The two bones of the fore-arm seen from the front. 1. The shaft of the ulna. 2. The greater sigmoid notch. 3. The lesser sigmoid notch, with which the head of the radius is articulated. 4. The olecranon process. 5. The coronoid process. 6. The nutritious foramen. 7. The sharp ridges upon the two bones to which the interosseous membrane is attached. 8. The capitulum ulnze. 9. The styloid process. 10. The shaft of the radius. 11. Its head sur- rounded by the smooth border for articulation with the orbicular ligament. 12. The neck of the radius. 13 Its gers § 14, The oblique line. 15. The lower extremity of the bone. 16. Its styloid process. G ,* eee J - ‘ Vr ( F2+ aa etn fe 82 RADIUS.—CARPUS, round above, where it supports the supinator brevis muscle, and marked by several shallow oblique grooves below, which afford attach- - ment to the extensor muscles of the thumb. The eaternal surface is rounded and convex, and marked by an oblique ridge, which extends from the tuberosity to the styloid process at the lower extremity of the bone. Upon the inner margin of the bone is a sharp and promi- nent crest, which gives attachment to the interosseous membrane. The lower extremity of the radius is broad and triangular, and pro- vided with two articular surfaces ; one at the side of the bone, which is concave to receive the rounded head of the ulna ; the other at the extremity, and marked by a slight ridge into two facets, one exter- nal and triangular, corresponding with the scaphoid ; the other square, with the semilunar bone. Upon the outer side of the extremity is a strong conical projection, the styloid process, which gives attachment by its base to the tendon of the supinator longus, and by its apex to the external lateral ligament of the wrist joint. The inner edge of the articular surface affords attachment to the base of the inter-arti- cular cartilage of the ulna. Immediately in front of the styloid process is a groove, which lodges the tendons of the extensor ossis metacarpi pollicis, and extensor primi internodii ; and behind the process a broader groove, for the tendons of the extensor carpi radialis longior and brevior, i * internodii ; behind this is a prominent ridge, and adeep and narrrow ’ groove, for the tendon of, the-ext diets ; and still farther back part of a broad groove, completed by the ulna, for the tendons of the extensor communis digitorum. - ba el ete Development.—By three centres; one for the shaft, and one for each extremity. Ossification commences in the shaft soon after the hu- merus, and before that in the ulna. The inferior centre appears during the second year, and the superior about the seventh. The bone is perfected at twenty. Articulations. —With four bones; humerus, ulna, scaphoid, and semilunar. Attachment of Muscles.—To nine ; by the tuberosity to the biceps ; by the oblique ridge to the supinator brevis, pronator radii teres, flexor sublimis digitorum and pronator quadratus; by the anterior surface, to the flexor longus pollicis and pronator quadratus ; by the posterior surface, to the extensor ossis metacarpi pollicis, and extensor primi internodii ; and by the styloid process, to the supinator longus. Carpus.—The bones of the carpus are eight in number ; they are arranged in.two rows. In the first row, commencing from the radial side, are the os scaphoides, semilunare, cuneiforme, pisiforme ; and in the second row, in the same order, the os trapezium, trapezoides, os magnum and unciforme. The ScapHor bone is named from bearing some resemblance to the shape of a boat, being broad at one end, and narrowed like a prow at the opposite, concave on one side, and convex upon the other. It SCAPHOID BONE.—SEMILUNARE. 63 is, however, more similar in form to a cashew nut, flattened and con- cave upon one side. If carefully examined, it will be found to pre- sent a convex and a concave surface, a convex and a concave border, a broad end, and a xarrow and pointed extremity, the tuberosity. To ascertain to which hand the bone belongs, let the student hold it horizontally, so that the convex surface may look backwards (z. e. towards himself), and the convex border upwards: the broad extremity will indicate its appropriate hand ; if it be directed to the right, the bone belongs to the right ; and if to the left, to the left carpus. Articulations —With five bones; by its convex surface with the radius ; by its concave surface, with the os magnum and semilunare ; Fig. 37.* and by the extremity of its upper or dorsal border, with the trape- zium and trapezoides. Attachments.—By its tuberosity to the abductor pollicis,-and ante- rior annular ligament. _ The seminunar bone may be known by having a crescentic con- cavity, and a somewhat crescentric outline. It presents for examina- tion four articular surfaces and two exiremities ; the articular surfaces are, one concave, one convex, and two /ateral, one lateral surface being crescentic, the other nearly circu- lar, and divided generally into two facets. The eatremities are, one dorsal, which is quadilateral, flat, and indented, for the attachment of ligaments ; the other palmar, which is convex, rounded, and of larger size. To determine to which hand it belongs, let the bone be held per- pendicularly, so that the dorsal or flat extremity look upwards, and the convex side backwards (towards the holder). The circular lateral * A diagram shewing the dorsal surface of the bones of the carpus, with their articulations. —The right hand. R. The lower end of the radius. U. The lower extremity of the ulna. F. The inter-articular fibro-cartilage attached to the styloid process of the ulna, and to the margin of the articular surface of the radius. S. The scaphoid bone: the numeral (5) indicates the number of bones with which it articulates, L. The semilunare articulating with five bones. C. The cuneiforme, articulating with three bones. P. The pisiforme, articulating with the cuneiforme only. TT. The first bone of the second row, the trapezium, articulating with four bones. T. The second bone, the trapezoides, articulating also with four bones. M. The os magnum, articulating with seven. U. The unciforme, articulating with five. The nu- merals, 1, 3, 1, 2, 1, on the metacarpal bones, refer to the number of their arti- culations with the carpal bones. 84 CUNEIFORME,—TRAPEZIUM. surface will point to the side corresponding with the hand to which. the bone belongs. ' Articulations.—With five bones, but occasionally with only four ; by its convex surface, with the radius ; by its concave surface, with the os magnum ; by its crescentic lateral facet, with the scaphoid ;. and by the circular surface, with the cuneiform bone and with the point of the unciform. This surface is divided into two parts by a ridge when it articulates with the unciform as well as with the cunei- form bone. The cunEIFoRM bone, although somewhat wedge-shaped in form, may be best distinguished by a circular and isolated facet, which arti- culates with the pisiform bone. It presents for examination three sur- Saces, a base, and an apex. One surface is very rough and irregular ; the opposite forms a concave articular surface, while the third is partly rough and partly smooth, and presents that circular facet which is characteristic of the bone. The base is an articular surface, and the apex is rough and pointed. To distinguish its appropriate hand, let the base be directed back- wards and the pisiform facet upwards ; the concave articular surface will point to the hand to which the bone belongs. Articulations.— With three bones, and with the triangular fibro- cartilage. By the base, with the semilunare ; by the concave surface, with the unciforme ; by the circular facet, with the pisiforme ; and by the superior angle of the rough surface, with the fibro-cartilage. The PistFoRM bone may be recognized by its small size, and by possessing a singular articular facet. If it be examined carefully, it will be observed to present four sides and two extremities ; one side is articular, the smooth facet approaching nearer to the superior than the inferior extremity. The side opposite to this is rounded, and the remaining sides are, one slightly concave, the other slightly convex. If the bone be held so that the articular facet shall look down- wards, and the extremity which overhangs the articular facet forwards, the concave side will point to the hand to which it belongs. Articulations.—W ith the cuneiform bone only. Attachments.—To two muscles, the flexor carpi ulnaris, and abduc- tor minimi digiti; and to the anterior annular ligament. The TRAPEzIUM (os multangulum majus) is too irregular in form to be compared to any known object; it may be distinguished by a deep groove, for the tendon of the flexor carpi radialis muscle. It is some- what compressed, and may be divided into two surfaces which are smooth and articular, and three rough borders. One of the articular surfaces is oval, concave in one direction, and convex in the other (saddle-seat shaped); the other is marked into three facets. One of the borders presents the groove for the tendon of the flexor carpi ra- dialis, which is surmounted by a prominent tubercle for the attach- ment of the annular ligament; the other two borders are rough and form the outer side of the carpus. The grooved border is narrow at i a A ee ae Pees es eee TRAPEZOIDES.—OS MAGNUM. 85. one extremity and broad at the other, where it presents the groove and tubercle. If the bone be held so that the grooved border look upwards while the apex of this border be directed forwards, and the base with the tubercle backwards, the concayo-convex surface will point to the hand to which the bone belongs. — Articulations—With four bones; by the concavo-convex surface, with the metacarpal bone of the thumb ; and by the three facets of the other articular surface, with the scaphoid, trapezoid, and second metacarpal bone. Attachments. —To two muscles, abductor pollicis and flexor ossis metacarpi ; and by the tubercle, to the annular ligament. The TRAPEzOIDES (os multangulum minus) is a small, oblong, and quadrilateral bone, bent near its middle upon itself (bean-shaped). It presents four articular surfaces and two extremities. One of the sur- faces is concavo-convex, 7. e. concave in one direction, and convex in the other; another, contiguous to the preceding, is concave, so as to be © almost angular in the middle, and is often marked by a small rough depression, for an interosseous ligament ; the two remaining sides are flat, and present nothing remarkable. One of the two extremities is broad and of large size, the dorsal ; the other, or palmar, is small and rough. If the bone be held perpendicularly, so that the broad extremity be upwards, and the concavo-convex surface forwards, the angular con- cave surface will point to the hand to which the bone belongs. Articulations.—With four bones; by the concayo-convex surface, with the second metacarpal bone; by the angular concave surface, with the os magnum ; and by the other two surfaces, with the trape- zium and scaphoid. Aittachments.—To the flexor brevis pollicis muscle. The os MAGNwuM (capitatum) is the largest bone of the carpus, and is divisible into a body and head. The head is round for the greater part of its extent, but is flattened on one side. The body is irregularly quadrilateral, and presents four sides and a smooth extremity. Two of the sides are rough, the one being square and flat, the dorsal, the other rounded and prominent, the palmar ; the other two sides are articular, the one being concave, the other convex. The extremity is a triangular articular surface, divided into three facets. If the bone be held perpendicularly, so that the articular extremity look upwards and the broad dorsal surface backwards (towards the holder), the concave articular surface will point to the hand to which the bone belongs. Articulations.—W ith seven bones; by the rounded head, with the cup formed by the scaphoid and semilunar bone ; by the side of the convex surface, with the trapezoides ; by the concave surface, with the unciforme ; and by the extremity, with the second, third, and fourth metacarpal bones. Attachments.—To the flexor brevis pollicis muscle. 86 UNC1FORME,. The UNCIFORME is a triangular-shaped bone, remarkable for a long and curved process, which projects from its palmar aspect. It pre- sents five surfaces ;—three articular, and two free. One of the arti- cular surfaces is divided by a slight ridge into two facets; the other two converge, and meet at a flattened angle.* One of the free sur- faces, the dorsal, is rough and triangular ; the other, palmar, also tri- angular, but somewhat smaller, gives origin to the unciform process. If the bone be held perpendicularly, so that the articular surface with two facets look upwards, and the unciform process backwards (towards the holder), the concavity of the unciform process will point to the hand to which the bone belongs. Articulations.— W ith five bones ; by the two facets on its base, with the fourth and fifth metacarpal bones ; by the two lateral articu- lating surfaces, with the magnum and cuneiforme ; and by the flat- tened angle of its apex, with the semilunare. Attachments.—To two muscles, adductor minimi digiti, and flexor brevis minimi digiti; and by the hook-shaped process to the annular ligament. Development.—The bones of the carpus are each developed by a single centre ; they are cartilagi- nous at birth. Ossification com- mences towards the end of the first year in the os magnum and unci- forme; at the end of the third year in the cuneiforme ; during the fifth year in the trapezium and se- milunare ; during the eighth, in the scaphoides ; the ninth, in the H trapezoides ; and the twelfth in the pisiforme. The latter bone is < last in the skeleton to ossify ; is, in reality, a sesamoid bone of the tendon of the flexor carpi ee naris. ce When the unciforme does not articulate with the semilunare, this angle is Ss. +t The hand viewed upon its anterior or palmar aspect. 1. The scaphoid bone. 2. The semilunare. 3. The cuneiforme. 4. The pisiforme. 5. The trapezium. 6. The oe in the trapezium that lodges the tendon of the fiexor carpi radialis. 7. The eranencitee 8. The os magnum. 9. The un- ciforme. 10,10. The ire metacarpal bones. 11, 11. The first row of phalan- ges. 12,12. The second row. 13, 13. The third row, or ungual phalanges. ta ae first phalanx of the thumb. 15. The second and last phalanx of the um Fig. 38.f METACARPUS, 87 The number of articulations which each bone of the carpus presents with surrounding bones, may be expressed in figures, which will materially facilitate their recollection ; the number for the first row is 5531, and for the second 4475. Meracarpus.—The bones of the metacarpus are five in number. They are long bones, divisible into a head, shaft, and base. The head is rounded at the extremity, and flattened at each side, for the insertion of strong ligaments ; the shaft is prismoid, and marked deeply on each side, for the attachment of the interossei muscles ; and the base is irregularly quadrilateral, and rough for the insertion of tendons and ligaments. The base presents three articular surfaces, one at each side, for the adjoining metacarpal bones ; and one at the extremity for the carpus. The metacarpal bone of the thumb is one-third shorter than the rest, flattened and broad on its dorsal aspect, and convex on its palmar side ; the articular surface of the head is not so round as that of the other metacarpal bones ; and the base has a single concavo- convex surface, to articulate with the similar surface of the trapezium. The metacarpal bones of the different fingers may be distinguished by certain obvious characters. The base of the metacarpal bone of the index finger is the largest of the four, and presents four articular surfaces. That of the middle finger may be distinguished by a rounded projecting process upon the radial side of its base, and two small circular facets upon its ulnar lateral surface. The base of the metacarpal bone of the ring-finger is small and square, and has two small circular facets to correspond with those of the middle meta- carpal. The metacarpal bone of the little finger has only one lateral articular surface. Development.—By two centres ; one for the shaft, and one for the digital extremity, with the exception of the metacarpal bone of the thumb, the epiphysis of which, like that of the phalanges, occupies the carpal end of the bone. Ossification of the metacarpal bones com- mences in the embryo between the tenth and twelfth week, that is, soon after the bones of the fore-arm. The epiphyses make their appear- ance at the end of the second, or early in the third year, and the bones are completed at twenty. Articulations.—The first with the trapezium ; second, with the tra- pezium, trapezoides, and os magnum, and with the middle metacarpal bone ; third, or middle, with the os magnum, and adjoining metacarpal bones ; fourth, with the os magnum and unciforme, and with the ad- joining metacarpal bones ; and, fifth, with the unciforme, and with the metacarpal bone of the ring-finger. The figures resulting from the number of articulations which each metacarpal bone possesses, taken from the radial to the ulnar side, are 13121. Attachment of Muscles.—To the metacarpal bone of the thumb, three, the flexor ossis metacarpi, extensor ossis metacarpi, and first 88 PHALANGES,—PELVIS. dorsal interosseous ; of the index finger, five, the extensor carpi radialis longior, flexor carpi radialis, first and second dorsal interosseous, and first palmar interosseous ; of the middle finger, four, the extensor carpi radialis brevior, adductor pollicis, and second and third dorsal in- terosseous ; of the ring-finger, three, the third and fourth dorsal inter- osseous, and second palmar; and of the little finger, fowr, extensor carpi ulnaris, adductor minimi digiti, fourth dorsal, and third palmar interosseous. PHALANGES.—The phalanges are the bones of the fingers ; they are named from their arrangement in rows, and are fourteen in number, three to each finger, and two to the thumb. In conformation they are long bones, divisible into a shaft, and two extremities. The shaft is compressed from before backwards, convex on its posterior surface, and flat with raised edges in front. The metacarpal extremity, or base, in the first row is a simple concave articular surface, that in the other two rows a double concavity, separated by a slight ridge. The digital extremities of the first and second row present a pulley-like surface, concave in the middle, and convex on each side. The ungual extremity of the last phalanx is broad, rough, and ex- panded into a semilunar crest. Development.—By two centres ; one for the shaft, and one for the base. Ossification commences first in the third phalanges, then in the first, and lastly in the second. The period of commencement corre- sponds with that of the metacarpal bones. The epiphyses of the first row appear during the third or fourth year, those of the second row during the fourth. or fifth, and of the last during the sixth or seventh. The phalanges are perfected by the twentieth year. Articulations.— The first row, with the metacarpal bones and second row of phalanges ; the second row, with the first and third ; and the third, with the second row. Attachment of Muscles——To the base of the first phalanx of the thumb four muscles, abductor pollicis, flexor brevis pollicis, adductor pollicis, and extensor primi internodii ; and to the second phalanzx, two, the flexor longus pollicis, and extensor secundi internodii. To the Jirst phalanx of the second, third, and fourth fingers, one dorsal and one palmar interosseous, and to the first phalanx of the little finger, the abductor minimi digiti, flexor brevis minimi digiti, and one palmar interosseous. To the second phalanges, the flexor sublimis and extensor communis digitorum ; and to the last phalanges, the flexor profundus and extensor communis digitorum. PELVIS AND LOWER EXTREMITY. The bones of the pelvis are the two ossa innominata, the sacrum and the coceyx ; and of the lower extremity, the femur, patella, tibia and fibula, tarsus, metatarsus, and phalanges. OS INNOMINATUM.—ILIUM. 89 Os INNOMINATUM.—The os innominatum (0s cox) is an irregular flat bone, consisting in the young subject of three parts, which meet at the acetabulum. Hence it is usually described in the adult as divi- sible into three portions, ilium, ischium, and pubes. The é/iwm is the Fig. 39.* Yj superior, broad, and expanded portion which forms the prominence of the hip, and articulates with the sacrum. The ischiwm is the inferior and strong part of the bone on which we sit. The os pubis is that portion which forms the front of the pelvis, and gives support to the external organs of generation. The 1L1um may be described as divisible into an internal and ex- ternal surface, a crest, and an anterior and posterior border. The internal surface is bounded above by the crest, below by a prominent line, the linea ilio-pectinea, and before and behind by * The os innominatum of the right side. 1. The ilium; its external surface. 2. Theischium. 3. The os pubis. 4. The crest of the ilium. 5. The supe- rior curved line. 6. The inferior curved line. 7. The surface for the gluteus maximus. 8. The anterior superior spinous process. 9. The anterior inferior spinous process. 10. The posterior superior spinous process. 11. The poste- rior inferior spinous process. 12. The spine of the ischium. 13. The great sacro-ischiatic notch. 14. The lesser sacro-ischiatic notch. 15. The tuber- osity of the ischium, shewing its three facets. 16. The ramus of the ischium. 17. The body of the os pubis. 18. The ramus of the pubes. 90 ISCHIUM. the anterior and posterior borders ; it is concave and smooth for the anterior two-thirds of its extent, and lodges the iliacus muscle. The posterior third is rough, for articulation with the sacrum, and is ‘divided by a deep grooye into two parts; an anterior or auri- cular portion, which is shaped like the pinna, and coated by carti- lage in the fresh bone ; and a posterior portion, which is very rough and uneven for the attachment of interosseous ligaments. The eaternal surface is uneven, partly convex, and partly concave ; it is bounded above by the crest ; below by a prominent arch, which forms the upper segment of the acetabulum ; and before and behind, by the anterior and posterior borders. Crossing this surface in an arched direction, from the anterior extremity of the crest to a notch upon the lower part of the posterior border, is a groove, which lodges the gluteal vessels and nerve, the superior curved line ; and below this, at a short distance, a rough ridge, the inferior curved line. The surface in- cluded between the superior curved line and the crest, gives origin to the gluteus medius muscle ; that between the curved lines, to the glu- teus minimus ; and the rough interval between the inferior curved line and the arch of the acetabulum, to one head of the rectus. The posterior sixth of this surface is rough and raised, and gives origin to part of the gluteus maximus. The crest of the ilium is arched and curved in its direction like the italic letter f, being bent inwards at its anterior termination, and out- wards towards the posterior. It is broad for the attachment of three planes of muscles, which are connected with its external and internal borders or lips, and with the intermediate space. The anterior border is marked by two projections, the anterior su- perior spinous process, which is the anterior termination of the crest, and the anterior inferior spinous process ; the two processes being se- parated by a notch for the attachment of the sartorius muscle. This border terminates inferiorly in the lip of the acetabulum. The poste- rior border also presents two projections, the posterior superior and the posterior inferior spinous process, separated by a notch. Inferiorly this border is broad and arched, and forms the upper part of the great sacro-ischiatic notch. The iscHium is divisible into a thick and solid portion, the body, and into a thin and ascending part, the ramus; it may be considered also, for convenience of description, as presenting an external and in- ternal surface, and three borders, posterior, inferior, and superior. The external surface is rough and uneven, for the attachment of muscles ; and broad and smooth above, where it enters into the forma- tion of the acetabulum. Below the inferior lip of the acetabulum is a notch, which lodges the obturator externus muscle in its passage outwards to the trochanteric fossa of the femur. The internal surface is smooth, and somewhat encroached upon at its posterior border by the spine. The posterior border of the ischium presents towards its middle a remarkable projection, the spine. Immediately above the spine is a OS PUBIs. 9t notch of large size, the great sacro-ischiatic, and below the spine the lesser sacro-ischiatic notch; the former being converted into a foramen by the lesser sacro-ischiatic ligament, gives passage to the pyriformis muscle, the gluteal vessels and nerve, pudic vessels and nerve, and ischiatic vessels and nerves; and the lesser, completed by the great sacro-ischiatic ligament, to the obturator internus muscle, and to the internal pudic vessels and nerve. The inferior border is thick and broad, and is called the tuberosity. The surface of the tuberosity is divided into three facets; one anterior, which is rough for the origin of the semi-membranosus ; and two posterior, which are smooth, and separated by a slight ridge for the semi-tendinosus and biceps muscle. The inner margin of the tuberosity is bounded by a sharp ridge, which gives attachment to a prolongation of the great sacro-is- chiatic ligament, and the outer margin by a prominent ridge, from which the quadratus femoris muscle arises. The superior border of the ischium is thin, and forms the lower circumference of the obtura- tor foramen. The ramus of the ischium is continuous with the ramus of the pubis, and is slightly everted. The os pusis is divided into a horizontal portion or body (hori- zontal ramus of Albinus), and a descending portion or ramus ; it pre- sents for examination an external and internal surface, a superior and inferior border, and symphysis. _ The external surface is rough, for the attachment of muscles ; and prominent at its outer extremity, where it forms part of the acetabu- lum. The internal surface is smooth, and enters into the formation of the cavity of the pelvis. The superior border is marked by a rough ridge, the crest ; the inner termination of the crest is the angle ; and the outer end, the spine or tubercle. Running outwards from the spine is a sharp ridge, the pectineal line, or linea ilio-pectinea, which marks the brim of the true pelvis. In front of the pectineal line is a smooth depression, which supports the femoral artery and vein, and a little more externally an elevated prominence, the #io-pectineal eminence, which divides the surface for the femoral vessels, from an- other depression which overhangs the acetabulum, and lodges the psoas and iliacus muscles. The ilio-pectineal eminence moreover marks the junction of the pubes with the ilium. The éxferior border is broad and deeply grooved, for the passage of the obturator vessels and nerve ; and sharp upon the side of the ramus, to form part of the boundary of the obturator foramen. The symphysis is the inner ex- tremity of the body of the bone ; it is oval and rough, for the attach- ment of a ligamentous structure analogous to the intervertebral sub- stance. The ramus of the pubes descends obliquely outwards, and is continuous with the ramus of the ischium. The inner border of the ramus forms with the corresponding bone the arch of the pubes, and at its inferior part is considerably everted, to afford attachment to the crus penis. The acetabulum (cavitas cotyloidea) is a deep cup-shaped cavity, situated at the point of union between the ilium, ischium, and pubes ; 92 ACETABULUM.—OBTURATOR FORAMEN, a little less than two-fifths being formed by the ilium, a little more than two-fifths by the ischium, and the remaining fifth by the pubes. It is bounded by a deep rim or lip, which is broad and strong above, ‘where most resistance is required, and marked in front by a deep notch, which is arched over in the fresh subject by a strong ligament, and transmits the nutrient vessels into the joint. At the bottom of the cup, and communicating with the notch, is a deep and circular pit (fundus acetabuli), which lodges a mass of fat, and gives attach- ment to the broad extremity of the ligamentum teres. The obturator or thyroid foramen is a large oval interval between the ischium and pubes, bounded by anarrow rough margin, to which a ligamentous membrane is attached. The upper part of the foramen is increased in depth by the groove in the under surface of the os pubis, which lodges the obturator vessels and nerve. Development.—By eight centres ; three principal, one for the ilium, one for the ischium, and one for the pubes ; and five secondary, one, the Y shaped piece for the interval between the primitive pieces in the acetabulum, one for the crest of the ilium, one (not constant) for the anterior and inferior spinous process of the ilium, one for the tuberosity of the ischium, and one (not constant) for the angle of the os pubis. Ossification commences in the primitive pieces, im- mediately after that in the vertebra, firstly in the ilium, then in the ischium, and lastly in the pubes ; the first ossific deposits being situated near to the future acetabulum. At birth, the acetabulum, the crest of the ilium, and the ramus of the pubes and ischium, are cartilaginous. The secondary centres appear at puberty, and the entire bone is not completed until the twenty-fifth year. Articulations.—With three bones ; sacrum, opposite innominatum, and femur. Attachment of Muscles and Ligaments.—To thirty-five muscles ; to the ilium, thirteen; by the outer lip of the crest, to the obliquus ex- ternus for two-thirds, and to the latissimus dorsi for one-third its length, and to the tensor vaginze femoris by its anterior fourth ; by the middle of the crest, to the internal oblique for three-fourths its length, by the remaining fourth to the erector spine ; by the internal lip, to the transversalis for three-fourths, and to the quadratus lumborum by the posterior part of its middle third. By the external surface, to the gluteus medius, minimus and maximus, and to one head of the rectus ; by the internal surface, to the iliacus ; and by the anterior border to the sartorius, and the other head of the rectus. To the ischium sixteen ; by its external surface, the adductor magnus and obturator externus ; by the internal surface, the obturator internus and levator ani; by the spine, the gemellus superior, levator ani, coccygeus, and lesser sacro-ischiatic ligament ; by the tuberosity, the biceps, semi- tendinosus, semi-membranosus, gemellus inferior, quadratus femoris, erector penis, tranversus perinei, and great sacro-ischiatic ligament ; and by the ramus, the gracilis, accelerator urine, and compressor urethre. To the os pubis fifteen ; by its upper border, the obliquus PELVIS. 93 externus, obliquus internus, tranversalis, rectus, pyramidalis, pecti- neus, and psoas parvus ; by its external surface, the adductor longus, adductor brevis and gracilis ; by its internal surface, the levator ani, compressor urethra, and obturator internus ; and by the ramus, the adductor magnus, and accelerator urinz. PELVIS. The pelvis considered as a whole is divisible into a false and true pelvis ; the former is the expanded portion, bounded on each side by Fig. 40.* * A female pelvis. 1. The last lumbar vertebra. 2, 2. The intervertebral substance connecting the last lumbar vertebra with the fourth and sacrum. 3. The promontory of the sacrum. 4. The anterior surface of the sacrum, on which its transverse lines and foramina are seen. 5, The tip of the coccyx. 6, 6. The iliac fossee, forming the lateral boundaries of the false pelvis. 7. The anterior superior spinous process of the ilium ; left side. 8. The anterior infe- rior spinous process. 9. The acetabulum. a. The notch of the acetabulum. b. The body of the ischium. c. Its tuberosity. d. The spine of the ischium seen through the obturator foramen. e. The os = f. The symphysis pu- bis. g. The arch of the pubes. h. The angle of the os pubis. i. The spine of the pubes; the prominent ridge between / and 7 is the crest of the pubes. k, k. The pectineal line of the pubes. /, /. The ilio-pectineal line; m, m, the prolongation of this line to the promontory of the sacrum. The line repre- sented by h,i. k, k. 1, 1. and m, m. is the brim of the true pelvis. 2. The ilio- pectineal eminence. 0. The smooth surface which supports the femoral vessels. Pp, p. The great sacro-ischiatic notch. 94 PELVIS. the ossa ilii, and separated from the true pelvis by the linea ilio- pectinea. The true pelvis is all that portion which is situated be- neath the linea ilio-pectinea. This line forms the margin or brim of the true pelvis, while the included area is called the inlet. The form of the inlet is heart-shaped, obtusely pointed in front at the symphysis pubis, expanded on each side, and encroached upon behind by a pro- jection of the upper part of the sacrum, which is named the pro- montory. The cavity is somewhat encroached upon at each side by a smooth quadrangular plane of bone, corresponding with the internal surface of the.acetabulum, and leading to the spine of the ischium. In front are two fossze around the obturator foramina, for lodging the ob- turator internus muscle, at each side. The inferior termination of the pelvis is very irregular, and is termed the outlet. It is bounded in front by the convergence of the rami of the ischium and pubes, which constitute the arch of the pubes ; on each side by the tuberosity of the ischium, and by two irregular fissures formed by the greater and lesser sacro-ischiatic notches ; and behind by the lateral borders of the sa- crum, and by the coccyx. The pelvis is placed obliquely with regard to the trunk of the body, so that the inner surface of the ossa pubis is directed upwards, and would support the superincumbent weight of the viscera. The base of the sacrum rises nearly four inches above the level of the upper border of the symphysis pubis and the apex of the coccyx, some- what more than half an inch above its lower border. Ifa line were carried through the central axis of the inlet, it would impinge by one extremity against the umbilicus, and by the other against the middle of the coceyx. The aais of the inlet is therefore directed downwards and backwards, while that of the outlet points downwards and forwards, and corresponds with a line drawn from the upper part of the sacrum, through the centre of the outlet. The axis of the cavity represents a curve, which corresponds very nearly with the curve of the sacrum, the extremities being indicated by the central points of the inlet and outlet. A knowledge of the direction of these axes is most important to the surgeon, as indicating the line in which instruments should be used in operations upon the viscera of the pelvis, and the direction of force in the removal of calculi from the bladder ; and to the accoucheur, as explaining the course taken by the foetus during parturition. There are certain striking differences between the male and female pelvis. In the male the bones are thicker, stronger, and more solid, and the cavity deeper and narrower. In the female the bones are lighter and more delicate, the iliac fossee are large, and the ilia ex- panded ; the inlet, the outlet, and the cavity, are large, and the acetabula farther removed from each other ; the cavity is shallow, the tuberosities widely separated, the obturator foramina triangular, and the span of the pubic arch greater, The precise diameter of the inlet and outlet, and the depth of the cavity, are important consider- ations to the accoucheur. The diameters of the inlet or brim are three: ]. Antero-posterior, ee ee a ee ee oe ree ee ly ee ee tur tedtetiea ee PELVIS.—FEMUR. 95 sacro-pubic or conjugate; 2. tranverse ; and 3. oblique. The an- tero-posterior extends from the symphysis pubis to the middle of the promontory of the sacrum, and measures four inches. The ¢ranverse extends from the middle of the brim on one side to the same point on the opposite, and measures five inches. The oblique extends from the sacro-iliac symphysis on one side, to the margin of the brim cor- responding with the acetabulum on the opposite, and also measures five inches. The diameters of the outlet are two, antero-posterior, and transverse. The antero-posterior diameter extends from the lower part of the sym- physis pubis to the apex of the coceyx ; and the ¢ranverse, from the posterior part of one tuberosity to the same point on the opposite side ; they both measure four inches. The cavity of the pelvis measures in depth four inches and a-half, posteriorly ; three inches and a-half in the middle ; and one and a half at the symphysis pubis. Femur. The femur, the longest bone of the skeleton, is situated obliquely in the upper part of the lower limb, articulating by means of its head with the acetabulum, and inclining inwards as it descends, until it almost meets its fellow of the opposite side at the knee. In the female this obliquity is greater than in the male, in consequence of the greater breadth of the pelvis. The femur is divisible into a shaft, a superior, and an inferior extremity. At the superior extremity is a rounded head, directed upwards and inwards, and marked just below its centre by an oval depression for the ligamentum teres. The head is supported by a eck, which varies in length and obliquity according to sex and at various periods of life, being long and oblique in the adult male, shorter and more horizontal in the female and in old age. Externally to the neck is a large pro- cess, the trochanter major, which presents upon its anterior surface an oval facet, for the attachment of the tendon of the gluteus minimus muscle ; and above, a double facet, for the insertion of the gluteus medius. On its posterior side is a vertical ridge, the linea quadrati for the attachment of the quadratus femoris muscle. Upon the inner - side of the trochanter major is a deep pit, the trochanteric or digital fossa, in which are inserted the tendons of the pyriformis, gemellus superior and inferior, and obturator externus and internus muscles. Passing downwards from the trochanter major in front of the bone is an oblique ridge, which forms the inferior boundary of the neck, the anterior intertrochanteric line; and behind, another oblique ridge, the posterior intertrochanteric line, which terminates in a rounded tu- bercle upon the posterior and inner side of the bone, the ¢rochanter minor. The shaft of the femur is convex and rounded in front, and covered with muscles ; and somewhat concave and raised into a rough and pro- minent ridge behind, the linea aspera. The linea aspera near the upper extremity of the bone divides into three branches. The anterior branch is continued forwards in front of the lesser trochanter, and is 96 FEMUR, continuous with the anterior intertrochanteric line ; the middle is con- tinued directly upwards into the linea quadrati; and the posterior, broad and strongly marked, ascends to the Fig. 41." base of the trochanter major. Towards the lower extremity of the bone the linea aspera divides into two ridges, which descend to the two condyles, and enclose a triangular space upon which rests the popliteal artery. The internal condyloid ridge is less marked than the external, and presents a broad and shallow groove, for the passage of the femoral artery. The nutritious foramen is situated in or near the linea aspera, at about one-third from its upper extremity, and is directed obliquely from below upwards. The lower eatremity of the femur is broad and porous, and divided by a smooth depres sion in front, and by a large fossa (fossa in- tercondyloidea) behind, into two condyles. The eaternal condyle is the broadest and most prominent, and the internal the narrow- est and longest ; the difference in length de- pending upon the obliquity of the femur, in consequence of the separation of the two bones at their upper extremities by the breadth of the pelvis. The external condyle is marked upon its outer side by a prominent tuberosity, which gives attachment to the external lateral ligament ; and immediately beneath this is the fossa, which lodges the tendon of origin of the popliteus. By the internal surface it gives attachment to the anterior crucial ligament of the knee-joint ; and by its upper and posterior part, to the external head of the gastrocnemius and to the plantaris. The internal condyle pro- jects upon its inner side into a tuberosity, to which is attached the internal lateral ligament ; above this tuberosity, at the extremity of the internal condyloid ridge, is a tubercle, for the insertion of the tendon of the adductor magnus ; and beneath the tubercle, upon the upper surface of the condyle, a depression, from which the internal head of the gastrocnemius arises. The outer * The right femur, seen upon the anterior aspect. 1. The shaft. 2. The head. 3. The neck. 4. The great trochanter. 5. The anterior intertrochan- teric line. 6. The lesser trochanter. 7. The external condyle. 8. The inter- nal condyle. 9. The tuberosity for the attachment of the external lateral liga- ment. 10. The fossa for the tendon of origin of the popliteus muscle. 11. The tuberosity for the attachment of the internal lateral ligament. FEMUR. 97 side of the internal condyle is rough and concave, for the attach- ment of the posterior crucial ligament. Development.—By five centres ; one for the shaft, one for each extremity, and one for each trochanter. The femur is the first of the long bones to shew signs of ossifica- tion. In it, ossific matter is found imme- diately after the maxille before the termi- nation of the second month of embryonic life. The secondary deposits take place in the following order, in the condyloid extre- mity during the last month of foetal life +; in the head towards the end of the first year ; in the greater trochanter between the third and the fourth year ; in the lesser trochanter between the thirteenth and fourteenth. The epiphyses and apophyses are joined to the diaphysis in the reverse order of their appearance, the junction commencing after puberty and not being completed for the condyloid epiphysis until after the twentieth year. Articulations.—W ith three bones ; with the os innominatum, tibia, and patella. Attachment of Muscles.—T 0 twenty-three ; by the greater trochanter, to the gluteus me- dius and minimus, pyriformis, gemellus su- perior, obturator internus, gemellus inferior, obturator externus, and quadratus femoris ; by the lesser trochanter, to the common ten- don of the psoas and iliacus. By the linea aspera, its outer lip, to the vastus externus, gluteus maximus, and short head of the bi- ceps ; by its inner lip, to the vastus inter- nus, pectineus, adductor brevis, and adduc- tor longus ; by its middle to the adductor magnus ; by the anterior part of the bone, to the crureeus and subcrurzeus ; by its con- dyles, to the gastrocnemius, plantaris, and popliteus. * A diagram of the posterior aspect of the right femur, shewing the lines of attachment of the muscles. The muscles attached to the inner lip are,—p, the pectineus ; a4, the adductor brevis ; and @/, the adductor longus. The middle portion is occupied for its whole extent by a m, the adductor us; and is continuous superiorly with q f, the linea quadrati, into which the quadratus femoris is inserted. The outer lip is occupied by g m, the gluteus maximus ; and 4, the short head of the biceps. + Cruveilheir remarks that this centre is so constant in the last fortnight of foetal life, that it may be regarded as an important proof of the foetus having reached its full term. J H 98 .PATELLA.—TIBIA. PaTELLA.—The patella is a sesamoid bone, developed in the ten- don of the quadriceps extensor muscle, and usually described as a bone of the lower extremity. It is heart-shaped in figure, the broad side being directed upwards and the apex downwards, the external surface convex, and the internal divided by a ridge Fig. 43*. into two smooth surfaces, to articulate with condyles of the femur. The external ar- ticular surface corresponding with the ex- ternal condyle is the larger of the two, and serves to indicate the leg to which the bone belongs. Development.—By a single centre, at about the middle of the third year. Articulations.—With the two condyles of the femur. Attachment of Muscles.—To four; the rectus, crureeus, vastus internus and vastus externus, and to the ligamentum patelle. Tip1a. — The tibia is the inner and larger bone of the leg; it is prismoid in form, and divisible into a shaft, an upper and lower extremity. The upper eatremity, or head, is large, and expanded on each side into two tube- rosities. Upon their upper surface the tu- berosities are smooth, to articulate with the condyles of the femur; the internal arti- cular surface being oval and oblong, to cor- respond with the internal condyle; and the external broad and nearly circular, Be- tween the two articular surfaces is a spinous process ; and in front and behind the spi- nous process a rough depression, giving at- tachment to the anterior and posterior crucial ligaments. Between the two tube- rosities on the front aspect of the bone is a prominent elevation, the tubercle, for the insertion of the ligamentum patella, and immediately above the tubercle a smooth facet, corresponding with a bursa. Upon the outer side of the external tuberosity is an articular surface, for the * The tibia and fibula of the right leg, articulated and seen from the front. 1. The shaft of the tibia. 2. The inner tuberosity. 3. The outer tuberosity. 4. The spinous process. 5. The tubercle. 6. The internal or subcutaneous surface of the shaft. 7. The lower extremity of the tibia. 8. The internal malleolus. 9. The shaft of the fibula. 10. Its upper extremity. 11. Its lower extremity, the external malleolus. The sharp border between 1 and 6 is the crest of the tibia. FIBULA. 99 head of the fibula ; and upon the posterior part of the internal tube- rosity a depression, for the insertion of the tendon of the semimem- branosus muscle. The shaft of the tibia presents three surfaces ; internal, which is subcutaneous and superficial ; eaternal, which is concave and marked by a sharp ridge, for the insertion of the interosseous membrane ; and posterior, grooved, for the attachment of muscles. Near the upper extremity of the posterior surface is an oblique ridge, the popliteal line, for the attachment of the fascia of the popliteus muscle ; and imme- diately below the oblique line, the nutritious canal, which is directed downwards. The inferior extremity of the bone is somewhat quadrilateral, and prolonged on its inner side into a large process, the internal malleolus. Behind the internal malleolus, is a broad and shallow groove, for lodging the tendons of the tibialis posticus and flexor longus digitorum ; and farther outwards another groove, for the tendon of the flexor longus pollicis. Upon the outer side the surface is concave and triangular, rough above, for the attachment of the interosseous ligament ; and smooth below, to articulate with the fibula. Upon the extremity of the bone is a triangular smooth surface, for articulating with the astragalus. . Development.—By three centres; one for the shaft, and one for each extremity. Ossification commences in the tibia, immediately after the femur; the centre for the head of the bone appears soon after birth, and that for the lower extremity during the second year ; the latter is the first to join the diaphysis. The bone is not complete until near the twenty-fifth year. Two occasional centres have some- times been found in the tibia, one in the tubercle, the other in the in- ternal malleolus. Articulations.—With three bones ; femur, fibula, and astragalus. Attachment of Muscles-—To ten; by the internal tuberosity, to the sartorius, gracilis, semitendinosus, and semimembranosus ; by the ex- ternal tuberosity, to the tibialis anticus and extensor longus digitorum ; by the tubercle, to the ligamentum patellz; by the external surface of the shaft, to the tibialis anticus ; and by the posterior surface, to the popliteus, soleus, flexor longus digitorum, and tibialis posticus. Freuta.—The fibula (#¢g4v7, a brooch, from its resemblance, in conjunction with the tibia, to the pin of an ancient brooch) is the outer and smaller bone of the leg ; it is long and slender in figure, prismoid in shape, and, like other long bones, is divisible into a shaft and two extremities. The superior extremity or head is thick and large, and depressed upon the upper part by a concave surface, which articulates with the external tuberosity of the tibia. Externally to this surface is a thick and rough prominence, for the attachment of the external lateral liga- ment of the knee-joint, terminated behind by a styloid process, for the insertion of the tendon of the biceps. 100 FIBULA. The lower eatremity is flattened from without inwards, and pro- longed downwards beyond the articular surface of the tibia, forming the external malleolus. Its external side presents a rough and tri- angular surface, which is subcutaneous. Upon the internal surface is a smooth triangular facet, to articulate with the astragalus ; and a rough depression, for the attachment of the interosseous ligament. The anterior border is thin and sharp ; and the posterior, broad and grooved, for the tendons of the peronei muscles. To place the bone in its proper position, and ascertain to which leg it belongs, let the inferior or flattened extremity be di- rected downwards, and the narrow border of the malleolus forwards ; the triangular subcutaneous surface will then point to the side corresponding with the limb of which the bone should form a part. The shaft of the fibula is prismoid, and presents three surfaces ; external, in- ternal, and posterior ; and three borders. The eaternal surface is the broadest of the three ; it commences upon the anterior part of the bone above, and curves around it so as to terminate upon its posterior side below. This surface is completely occu- pied by the two peronei muscles. The internal surface commences on the side of the superior articular surface, and termi- nates below, by narrowing to a ridge, which is continuous with the anterior bor- der of the malleolus. It is marked along its middle by the interosseous ridge, which is lost above and below in the inner bor- der of the bone. The posterior surface is twisted like the external, it commences above on the posterior side of the bone, and terminates below on its internal side ; at about the middle of this surface is the nutritious foramen, which is directed down- wards. The internal border commences superior- ly in common with the interosseous ridge, and bifurcates inferiorly into two lines, * The tibia and fibula of the right leg articulated and seen from behind. 1. The articular depression for the external condyle of thefemur. 2. The articular depression for the internal condyle ; the prominence between the two numbers is the spinous process. 3. The fossa and groove for the insertion of the tendon of the semi-membranosus muscle. 4. The popliteal plane, for the support of the popliteus muscle. 5. The popliteal line. 6. The nutritious foramen. 7. eee On Se ee ee TARSUS,—ASTRAGALUS. 101 which bound the triangular subcutaneous surface of the external mal- leolus. The eaternal border begins at the base of the styloid process upon the head of the fibula, and winds around the bone, following the direction of the corresponding surface. The posterior border is sharp and prominent, and is lost inferiorly in the interosseous ridge. Development.—By three centres; one for the shaft, and one for each extremity. Ossification commences in the shaft soon after its ap- pearance in the tibia ; at birth the extremities are cartilaginous, an ossific deposit taking place in the inferior epiphysis during the second year, and in the superior during the fourth or fifth. The inferior epi- physis is the first to become united with the diaphysis, but the bone is not completed until nearly the twenty-fifth year. Articulations.— W ith the tibia and astragalus. Attachment of Muscles.—To nine; by the head, to the tendon of the biceps and soleus ; by the shaft, its external surface, to the per- oneus longus and brevis; internal surface, to the extensor longus digitorum, extensor proprius pollicis, peroneus tertius, and tibialis wee by the posterior surface, to the popliteus and flexor longus pollicis. Tarsus.—The bones of the tarsus are seven in number ; viz. the astragalus, calcaneus, scaphoid, internal middle, and external cuneiform and cuboid. The AsrraGALuvs (os tali) may be recognised by its rounded head, a broad articular facet upon its convex surface, and two articular facets, separated by a deep grove, upon its concave surface. The bone is divisible into a superior and inferior surface, an external and internal border, and an anterior and posterior extremity. The sw- perior surface is convex, and presents a large quadrilateral and smooth facet somewhat broader in front than behind, to articulate with the tibia. The inferior surface is concave, and divided by a deep and rough groove (sulcus tali), which lodges a strong interosseous ligament, into two facets, the posterior large and quadrangular, and the anterior smaller and elliptic, which articulate with the os calcis. The tnternal border is flat and irregular, and marked by a pyriform articular sur- face, for the inner malleolus. The eaternal presents a large triangular articular facet, for the external malleolus, and is rough and concave in front. The anterior extremity presents a rounded head, surrounded by The surface of the shaft upon which the flexor longus digitorum muscle rests. 8. The broad groove on the back part of the inner Siaileshis: for the tendons of the flexor longus digitorum and tibialis posticus. 9. The groove for the tendon of the flexor longus pollicis. 10. The shaft of the fibula. The flexor longus pollicis muscle lies upon this surface of the bone; its superior limit bein marked by the oblique line immediately above the number. 11. The styloi process on the head of the fibula for the attachment of the tendon of the biceps muscle, 12. The subcutaneous surface of the lower part of the shaft of the fibula. 13. The external malleolus formed by the lower extremity of the fibula. 14, The groove upon the posterior part of the external malleolus for the ten- dons of the peronei muscles. 102 CALCANEUS, a constriction somewhat resembling a neck ; and the posterior ea- tremity is narrow, and marked by a deep groove, for the tendon of the ‘flexor longus pollicis. Hold the astragalus with the broad articular surface upwards, and the rourded head forwards; the triangular lateral articular surface will point to the side to which the bone belongs. Articulations.—W ith four bones ; tibia, fibula, calcaneus, and sca- phoid. The Catcanevus (os calcis) may be known by its large size and oblong figure, by the large and irregular portion which forms the heel, and by two articular surfaces, separated by a broad groove upon its upper side. The calcaneus is divisible into four surfaces, superior, inferior, ex- ternal, and internal ; and two ex- tremities, anterior and posterior. The superior surface is convex be- hind and irregularly concave in front, where it presents two, and some- times three articular facets, divided by a broad and shallow groove (sul- cus calcanei), for the interosseous li- gament. The inferior surface is con- vex and rough, and bounded poste- riorly by the two inferior tuberosi- ties, of which the internal is broad and large, and the external smaller and prominent. The eaternal sur- face is convex and subcutaneous, and marked towards its anterior third by two grooves, often sepa- rated by a tubercle, for the tendons of the peroneus longus and brevis. The internal surface is concave and grooved, for the tendons and vessels which pass into the sole of the foot. At the anterior extremi- ty of this surface is a projecting pro- Fig. 45.% * The dorsal surface of the left foot. 1. The astragalus; its superior qua- drilateral articular surface. 2. The anterior extremity of the astragalus, which articulates with (4) the scaphoid bone. 3. The calcaneus. 4. The scaphoid bone. 5. The internal cuneiform bone. 6. The middle cuneiform bone. 7. The external cuneiform bone. 8. The cuboid bone. 9. The metatarsal bones of the first and second toes. 10. The first phalanx of the great toe 11. The second phalanx of the great toe. 12. The first phalanx of the second toe. 13. Its second phalanx. 14. Its third phalanx. ; SCAPHOID. 103 cess (sustentaculum tali,) which supports the anterior articulating surface of the astragalus, and serves as a pulley to the tendon of the flexor longus digitorum. Upon the anterior eatremity is a flat arti- cular surface, surmounted by a rough projection, which affords one of the guides to the surgeon in the performance of Chopart’s operation. The posterior eatremity is prominent and convex, and constitutes the posterior tuberosity ; it is smoooth for the upper half of its extent, where it corresponds with a bursa ; and rough below, for the insertion of the tendo Achillis ; the lower part of this surface is bounded by the two inferior tuberosities. Articulations—With two bones; the astragalus and cuboid. In their articulated state a large oblique canal is situated between the astragalus and calcaneus, being formed by the apposition of the two grooves sulcus tali and calcanei. This groove is called the sinus éarsi, and serves to lodge a strong interosseous ligament which binds the two bones together. Attachment of Muscles——To nine; by the posterior tuberosity, to the tendo Achillis and plantaris; by the inferior tuberosities and under surface, to the abductor pollicis, abductor minimi digiti, flexor brevis digitorum, flexor accessorius, and to the plantar fascia; and by the external surface, to the extensor brevis digitorum. The ScarHorp bone may be distinguished by its boat-like figure, concave on one side, and convex with three facets upon the other. It presents for examination an anterior and posterior surface, a supe- rior and inferior border, and two extremities, one broad, the other pointed and thick. The anterior surface is convex, and divided into three facets, to articulate with the three cuneiform bones ; and the pos- terior concave, to articulate with the rounded head of the astragalus. The superior border is convex and rough, and the inferior somewhat concave and irregular. The eaternal extremity is broad and rough, and the internal pointed and prominent, so as to form a tuberosity. The external extremity sometimes presents a facet of articulation with the cuboid. If the bone be held so that the convex surface with three facets look forwards, and the convex border upwards, the broad extremity will point to the side corresponding with the foot to which the bone belongs. Articulations.—W ith four bones ; astragalus and three cuneiform bones, sometimes also with the cuboid. Aitachment of Muscles.—To the tendon of the tibialis posticus. The INTERNAL CUNEIFORM may be known by its irregular wedge- shape, and by being larger than the two other bones bearing the same name. It presents for examination a convex and a concave sur- face, a long and a short articular border, and a smal! and a large extremity. Place the bone so that the small extremity may look upwards and 104 CUNEIFORM BONES. the long articular border forwards, the concave surface will point to the side corresponding with the foot to which it belongs. _~ The convew surface is internal and free, and assists im forming the inner border of the foot, the concave is external, and in apposition with the middle cuneiform and second metatarsal bone ; the long border articulates with the metatarsal bone of the great toe, and the short border with the scaphoid bone. The small extremity (edge) is sharp, and the larger extremity (base) rounded into a broad tube- rosity. Articulations.—W ith four bones ; scaphoid, middle cuneiform, and first two metatarsal bones. Attachment of Muscles.—To the tibialis anticus, and posticus. The Mippiz Cunetrrorm is the smallest of the three; it is wedge- shaped, the broad extremity being placed upwards, and the sharp end downwards in the foot. It presents for examination four articular surfaces and two extremities. The anterior and posterior surfaces have nothing worthy of remark. One of the /ateral surfaces has a long articular facet, extending its whole length, for the internal cunei- form; the other has only a partial articular facet for the external cuneiform bone. If the bone be held so that the square extremity look upwards, the broadest side of the square being towards the holder, the small and partial articular surface will point to the side to which the bone belongs. Articulations.—W ith four bones ; scaphoid, internal and external cuneiform, and second metatarsal bone. Attachment of Muscles.—To the flexor brevis pollicis. The ExTERNAL CUNEIFORM is intermediate in size between the two preceding, and placed, like the middle, with the broad end up- wards and the sharp extremity downwards. It presents for examina- tion five surfaces, and a superior and inferior extremity. The upper eatremity is flat, of an oblong square form, and bevelled posteriorly, at the expense of the outer surface, into a sharp edge. If the bone be held so that the square extremity look upwards and the sharp border backwards, the bevelled surface will point to the side corresponding with the foot to which the bone belongs. Articulations.—W ith six bones; scaphoid, middle cuneiform, cuboid, and second, third, and fourth metatarsal bones. Attachment of Muscles.—To the flexor brevis pollicis. _ The Cusomw Bonz is irregularly cuboid in form, and marked upon its under surface by a deep groove, for the tendon of the peroneus longus muscle. It presents for examination six surfaces, three articular and three non-articular. The non-articular surfaces are the superior, which is slightly convex, and assists in forming the dorsum of the METATARSAL BONES. 105 foot; the inferior, marked by a prominent ridge, the twherosity, and a deep groove for the tendon of the peroneus longus; and an eaternal, the smallest of the whole, and deeply notched by the commencement of the peroneal groove. The articular surfaces are, the posterior, which is of large size, and concayo-convex, to articulate with the os calcis ; anterior, of smaller size, divided by a slight ridge into two facets, for the fourth and fifth metatarsal bones; and internal, a small oval articu- lar facet, upon a large and quadrangular surface, for the external cuneiform bone. If the bone be held so that the plantar surface, with the peroneal groove, look downwards, and the largest articular surface backwards, the small non-articular surface, marked by the deep notch, will point to the side corresponding with the foot to which the bone belongs. Articulations.—W ith four bones ; calcaneus, external cuneiform, and fourth and fifth metatarsal bones, sometimes also with the scaphoid. Attachment of Muscles.—To three ; the flexor brevis pollicis, adduc- tor pollicis, and flexor brevis minimi digiti. Upon a consideration of the articulations of the tarsus it will be ob- served, that each bone articulates with four adjoining bones, with the exception of the calcaneus, which articulates with two, and the exter- nal cuneiform with six. Development.—By a single centre for each bone, with the exception of the os calcis, which has an epiphysis for its posterior tuberosity. The centres appear in the following order; calcanean, sixth month ; astragalan, seventh month; cuboid, tenth month; external cuneiform, during the first year; internal cuneiform, during the third year; middle cuneiform and scaphoid, during the fourth year. The epiphysis of the calcaneus appears at the ninth year and is united with the dia- physis at about the fifteenth. The MeraTaRsaL BONES, five in number, are long bones, and divi- sible therefore into a shaft and two extremities. The shaft is pris- moid, and compressed from side to side; the posterior extremity, or base, is square-shaped, to articulate with the tarsal bones, and with each other; and the anterior extremity presents a rounded head, cir- cumscribed by a neck, to articulate with the first row of phalanges. Peculiar Metatarsal bones.—The first is shorter and larger than the rest, and forms part of the inner border of the foot; its-posterior ex- tremity presents only one lateral articular surface, and an oval rough prominence beneath, for the insertion of the tendon of the peroneus longus. The anterior extremity has, upon its plantar surface, two grooved facets, for sesamoid bones. The second is the longest and largest of the remaining metatarsal bones ; it presents at its base three articular facets, for the three cunei- form bones; a large oval facet, but often no articular surface, on its inner side, to articulate with the metatarsal bone of the great toe, and two externally, for the third metatarsal bone. The third may be known by two facets upon the outer side of its 106 METATARSAL BONES. base, corresponding with the second, and may be distinguished by its smaller size. _ The fourth may be distinguished by its smaller size, and by having a single articular surface on each Fig. 46.* side of the base. The fifth is recognised by its broad base, and by its large tubero- sity in place of an articular surface upon its outer side. Development.— Each bone by two centres ; one for the body and one for the digital extremity in the four outer metatarsal bones ; and one for the body, the other for the base in the metatarsal bone of the great toe. Ossifie deposition appears in these bones at the same time with the vertebree ; the epiphyses, commen- cing with the great toe and proceed- ing to the fifth, appear towards the close of the second year, consolida- tion being effected at eighteen. Articulations. — With the tarsal bones by one extremity, and with the first row of phalanges by the other. The number of tarsal bones with which each metatarsal articu- lates from within outwards, is the same as between the metacarpus and carpus, one for the first, three for the second, one for the third, two for the fourth, and one for the fifth, forming the cipher 13121. Attachment of Muscles.—To fourteen; to the first, the peroneus longus and first dorsal interosseous muscle; to the second, two dorsal interrossei and transversus pedis; to the third, two dorsal and one plantar interosseous, adductor pollicis and transversus pedis; to the fourth, two dorsal and one plantar interosseous, adductor pollicis and * The sole of the left foot. 1. The inner tuberosity of the os calcis. 2. The outer tuberosity. . Its posterior tuberosity. 3. The groove for the tendon of the flexor longus digitorum ; this figure indicates also the sustentaculum tali. 4. The rounded head of the astragalus. 5. The scaphoid bone. ‘6. Its tube- rosity. 7. The internal cuneiform bone; its broad extremity. 8. The middle cuneiform bone. 9. The external cuneiform bone. 10, 11. The cuboid bone. 11. Refers to the groove for the tendon of the peroneus longus : the prominence between this groove and figure 10 is the tuberosity. 12, 12. The metatarsal bones. 13, 13. The first phalanges. 14, 14. The second phalanges of the four lesser toes. 15,15. The third, or ungual phalanges of the four lesser toes. 16. The last phalanx of the great toe. nace Se ees EWR eee oe ee ee aye Ch keg OO Hee Be PHALANGES, 107 transversus pedis ; to the fifth, one dorsal and one plantar interrosseous peroneus brevis, peroneus tertius, abductor minimi digiti, flexor brevis minimi digiti, and transversus pedis. PuHALANGES.—There are.two phalanges in the great toe, and three in the other toes, as in the hand. They are long bones, divisible into a central portion and extremities. The phalanges of the first row are convex above, concave upon the under surface, and compressed from side to side. The posterior extremity has a single concave articular surface, for the head of the metatarsal bone; and the anterior extremity, a pulley-like surface, for the second phalanx. The second phalanges are short and diminutive, but somewhat broader than those of the first row. The third, or ungual phalanges, including the second phalanx of the great toe, are flattened from above downwards, spread out laterally at the base, to articulate with the second row, and at the opposite ex- tremity, to support the nail and the rounded extremity of the toe. Development.—By two centres; one for the body and one for the metacarpal extremity. Ossification commences in these bones after that in the metatarsus, appearing first in the last phalanges, then in the first, and last of all in the middle row. The bones are completed at eighteen. Articulations.—The first row with the metatarsal bones and second phalanges; the second, of the great toe with the first phalanx, and of the other toes with the first and third phalanges; and the third, with the second row. Attachment of Muscles.—To twenty-three; to the first phalanges ; great toe, the innermost tendon of the extensor brevis digitorum, ab- ductor pollicis, adductor pollicis, flexor brevis pollicis, and transversus pedis ; second toe, first dorsal and first palmar interosseous and lum- bricalis ; third toe, second dorsal and second palmar interrosseous and lumbricalis ; fourth toe, third dorsal and third palmar interrosseous and lumbricalis ; fifth toe, fourth dorsal interosseous, abductor minimi digiti, flexor brevis minimi digiti and lumbricalis. Second phalanges ; great toe, extensor longus pollicis, and flexor longus pollicis ; other toes, one slip of the common tendon of the extensor longus and extensor brevis digitorum, and flexor brevis digitorum. Third phalanges ; two slips of the common tendon of the extensor longus and extensor brevis digitorum, and the flexor longus digitorum. Szsamom Bonss.—These are small osseous masses, developed in those tendons which exert a certain degree of force upon the surface over which they glide, or where, by continued pressure and friction, the tendon would become a source of irritation to neighbouring parts, as to joints. The best example of a sesamoid bone is the patella, de- veloped in the common tendon of the quadriceps extensor, and resting upon the front of the knee-joint. Besides the patella, there are four 108 SESAMOID BONES. pairs of sesamoid bones included in the number of pieces which com- pose the skeleton, two upon the metacarpo-phalangeal articulation of each thumb, and existing in the tendons of insertion of the flexor brevis pollicis, and two upon the corresponding joint in the foot, in the tendons of the muscles inserted into the base of the first phalanx. In addition to these there is often a sesamoid bone upon the meta- carpo-phalangeal joint of the little finger ; and upon the corresponding joint in the foot, in the tendons inserted into the base of the first phalanx; there is one also in the tendon of the peroneus longus muscle, where it glides through the groove in the cuboid bone; some- times in the tendons, as they wind around the inner and outer malleolus; in the psoas and iliacus, where they glide over the body of the os pubis; and in the external head of the gastrocnemius. The bones of the tympanum, as they belong to the apparatus of hear- ing, will be described with the anatomy of the ear. 109 CHAPTER II. ON THE LIGAMENTS. Tue bones are variously connected with each other in the construc- tion of the skeleton, and the connection between any two bones con- stitutes a joint orarticulation. If the joint be immovable, the sur- faces of the bones are applied in direct contact ; but if motion be in- tended, the opposing surfaces are expanded, and coated by an elastic. substance, named cartilage ; a fluid secreted by a membrane closed on all sides lubricates their surface, and they are firmly held together by means of short bands of glistening fibres, which are called ligaments ligare, to bind). The study of the ligaments is named syndesmolo a together, eczes bond), which, with the anatomy of TEs articoke tions, forms the subject of the present chapter. The forms of articulation met with in the human frame may be considered under three classes :—Synarthrosis, Amphi-arthrosis, and Diarthrosis. SyNARTHROSIS (civ, Ze¢gwors articulation) is expressive of the fixed form of joint in which the bones are immovably connected with each other.. The kinds of synarthrosis are four in number. 1. Sutura. 2. Harmonia. 3. Schindylesis. 4. Gomphosis. The characters of the three first have been sufficiently explained in the preceding chap- ter, p. 52. It is here only necessary to state that, in the construction of sutures, the substance of the bones is not in immediate contact, but is separated by a layer of membrane which is continuous exter- nally with the pericranium and internally with the dura mater. It is the latter connection which gives rise to the great difficulty sometimes experienced in tearing the calvarium from the dura mater. Cruveil- hier describes this interposed membrane as the swtwral cartilage ; I never saw any structure in the sutures which could be regarded as cartilage, and the history of the formation of the cranial bones would seem to point to a different explanation. The fourth, Gomphosis (youGos, a nail), is expressive of the insertion of one bone into another, in the same manner that a nail is fixed into a board ; this is illus- trated in the articulation of the teeth with the alveoli of the maxillary bones. AMPHI-ARTHROSIS (Zui both, Zeégwois) is a joint intermediate in aptitude for motion between the immovable synarthrosis and the movable diarthrosis. It is constituted by the approximation of sur- faces partly coated with cartilage lined by synovial membrane, and 110 ARTICULATIONS. partly connected by interosseous ligaments, or by the intervention of an elastic fibro-cartilage which adheres to the ends of both bones. Examples of this articulation are seen in the union between the bodies of the vertebrae, of the sacrum with the coccyx, of the pieces of the sternum, the sacro-iliac and pubic symphyses (cd», @vev to grow to- gether), and according to some, of the necks of the ribs, with the transverse processes. , DrarTuHrRosis (dc through, zeéewess) is the movable articulation, which constitutes by far the greater number of the joints of the body. The degree of motion in this class has given rise to a subdivision into three genera, Arthrodia, Ginglymus, and Enarthrosis. Arthrodia is the movable joint in which the extent of motion is slight and limited, as in the articulation of the clavicle, of the ribs, articular processes of the vertebra, axis with the atlas, radius with the ulna, fibula with the tibia, carpal and metacarpal, tarsal and meta- tarsal bones. Ginglymus (yiyyavuos, a hinge), or hinge-joint, is the movement of bones upon each other in two directions only, viz. forwards and backwards ; but the degree of motion may be very considerable. The instances of this form of joint are numerous ; they comprehend the elbow, wrist, metacarpo-phalangeal and phalangeal joints in the upper extremity ; and the knee, ankle, metatarso-phalangeal and phalangeal joints in the lower extremity. The lower jaw may also be admitted into this category, as partaking more of the character of the hinge- joint than of the less movable arthrodia. The form of the ginglymoid joint is somewhat quadrilateral, and each of its four sides is provided with a ligament, which is named from its position, anterior, posterior, internal, or external lateral. The lateral ligaments are thick and strong, and are the chief bond of union between the bones. The anterior and posterior are thin and loose in order to permit the required extent of movement. Enarthrosis (iv in, égéewors) is the most extensive in its range of motion of all the movable joints. From the manner of connection and form of the bones in this articulation, it is called the ball and socket-joint. There are two instances in the body, viz. the hip and the shoulder. I have been in the habit of adding to the preceding the carpo-meta- carpal articulation of the thumb, although not strictly a ball-and- socket joint, from the great extent of motion which it enjoys, and from the nature of the ligament connecting the bones. As far as the articular surfaces are concerned, it is rather a double than a single ball-and-socket, and the whole of these considerations remove it from the simple arthrodial and ginglymoid groups. The ball and socket-joint has a circular form ; and, in place of the four distinct ligaments of the ginglymus, is enclosed in a bag of liga- mentous membrane, called a capsular ligament. The kinds of articulation may probably be conveyed in a more sa- tisfactory manner in the tabular form, thus: MOVEMENTS OF JOINTS. lll Examples. Sutura . . . ._ bones of the skull, Gynareten Harmonia . . . superior maxillary bones. ee Schindylesis . . vomer with rostrum. Gomphosis. . . teeth with alveoli. Amphi-arthrosis . Bodies of the vertebre . Symphyses. Arthrodia . . . carpal and tarsal bones. Diarthrosis. < Ginglymus. . . elbow, wrist, knee, ankle. : Enarthrosis . . hip, shoulder. The motions permitted in joints may be referred to four heads, viz. 1. Gliding. 2. Angular movement. 3. Circumduction. 4. Rotation. 1. Gliding is the simple movement of one articular surface upon another, and exists to a greater or less extent in all the joints. In the least movable joints as in the carpus and tarsus, this is the only mo- tion which is permitted. 2. Angular movement may be performed in four different directions, either forwards and backwards, as in flexion and extension ; or inwards and outwards, constituting adduction and abduction. Flexion and ex- tension are illustrated in the ginglymoid joint, and exist in a large proportion of the joints of the body. Adduction and abduction con- joined with flexion and extension, are met with complete, only in the -most movable joints, as in the shoulder, the hip, and the thumb. In the wrist and in the ankle adduction and abduction are only partial. 3. Circumduction is most strikingly exhibited in the shoulder and hip joints ; it consists in the slight degree of motion which takes place in the head of a bone against its articular cavity, while the extremity of the limb is made to describe a large circle upon a plane surface. It is also seen, but in a less degree, in the carpo-metacarpal articulation of the thumb, metacarpo-phalangeal articulations of the fingers and toes, and in the elbow when that joint is flexed and the end of the humerus fixed. 4. Rotation is the movement of a bone upon its own axis, and is illustrated in the hip and shoulder, or better in the rotation of the cup of the radius, against the eminentia capitata of the humerus. Rota- tion is also observed in the movements of the atlas upon the axis, in which the odontoid process serves as a pivot around which the atlas turns. The structures entering into the composition of a joint are bone, cartilage, fibrous tissue, adipose tissue, and synovial membrane. Car- tilage forms a thin coating to the articular extremities of bones, some- times presenting a smooth surface which moves on a corresponding smooth surface of the articulating bone; sometimes forming a plate smooth on both surfaces and interposed between the cartilaginous ends of two bones, interarticular ; and sometimes acting as the connecting medium between bones without any free surface, interosseous. Fibrous tissue enters into the construction of joints under the form of ligament, in one situation constituting bands of various breadth and thickness, 112 STRUCTURE OF CARTILAGE. in another a layer which extends completely around the joint and is then called a capsular ligament. All the ligaments of joints are com- posed of that variety of fibrous tissue termed white fibrous tissue, but in some situations ligaments are found which consist of yellow fibrous tissue, for example, the ligamenta subflava of the arches of the verte- bral column. Adipose tissue exists in variable quantity in relation with joints, where it performs, among other offices, that of a valve or spring, which occupies any vacant space that may be formed during the movements of the joint, and effectually prevents the occurrence of a vacuum in those cavities. This purpose of adipose tissue is exem- plified in the cushion of fat at the bottom of the acetabulum and in the similar cushion behind the ligamentum patella. Synovial mem- brane constitutes the beautiful smooth and polished lining of a joint, and contains the fluid termed synovia by means of which the adapted surfaces are enabled to move upon each other with the perfect ease and freedom which are known to exist. CaARTILAGE.—In the structure of joints, cartilage serves the doable purpose of a connecting and separating medium. In the former capa- city possessing great strength, and in the latter smoothness and elasti- city. In reference to its intimate structure it admits of classification into three kinds, true cartilage, reticular cartilage, and fibrous car- tilage. True Cartilage is composed of a semi-transparent homogeneous sub- stance (hyaline or vitreous substance) containing a number of minute cells (cartilage corpuscles) dispersed at short intervals through its ; G Z Ww E> o GEL ED Ss OTD e 4 ASS Oe y= a AL ¢ , j Hy JY & © @QH < BD ) Gyp) * is oe te [oT Qe \ LFS Mae“ CQ ey <- * A portion of articular cartilage from the head of the fibula. The section is made vertically to the surface, and magnified 155 times. a. The appearance and arrangement of the cells near to the bone. The irregular line to the right is the boundary of the bone. 3B. A view of the same section, at about midway between the bone and the free surface. c. A portion near the synovial surface ; the line to the left is that of the synovial boundary. STRUCTURE OF CARTILAGE. 113 ‘ig. 47, B. sg : eh Wi eile | Hh Ae dp HH | —— $$ ~~ a a) a oe ah structure. The cells are oval, oblong, or polyhedral in shape, and more or less flattened ; their membranous envelope is blended with the intercellular substance, and they contain in their interior secondary cells, nuclei, nucleoli, oil globules, and more or less of granular matter. Cartilage cells have an average measurement of +345 of an inch in their long diameter; they are sometimes isolated, sometimes grouped in pairs, and sometimes disposed in a linear group of three or four. They are larger near the bone than at the surface, and in the latter situation are long and slender in form, and arranged in rows having their long axis parallel with the plane of the surface. True cartilage is pearl-white or bluish and opaline in colour, and its intercellular substance is semitransparent and structureless. These characters, however, are changed when it exhibits a tendency to ossify. In the latter case the intercellular substance becomes fibrous and more or less opake, its colour is yellowish, and the cells are found to contain a greater- Fig. 48.+ number of oil-globules than in its natu- ral state. The true cartilages are, the articular, costal, ensiform, thyroid, cricoid, ary- tenoid, tracheal and bronchial, nasal, meatus auris, the pulley of the troch- learis muscle, and temporary cartilage or the cartilage of bone previously to ossification.* Reticular cartilage is composed of , cells (=s'5pth of an inch in diameter) * Page 5. + A portion of reticular cartilage. The section is taken from the pinna, and magnified 155 times. I 114 STRUCTURE OF FIBROUS TISSUE. separated from each other by an opake, subfibrous, intercellular net- work, the breadth of the cells being considerably greater than that of the intercellular structure. The cells are parent cells, containing others of secondary formation, together with nuclei, nucleoli, granular matter, and oil-globules in greater number than those of true car- tilage. The fibres are short, imperfect, loose in texture, and yel- lowish. The instances of reticular cartilage are, the pinna, epiglottis, and Eustachian tube. Fibrous cartilage is composed of a network of white glistening fibres collected into fasciculi of various size, and containing in its Fig. 49.* meshes cells and a subfibrous tissue resembling that of reticular cartilage. The fibres of fibrous cartilage are identical with those of fibrous tissue, the cells are large (about =',5th of an inch) as in reti- cular cartilage, and the areole are variable in dimensions. It is this latter character that constitutes the difference between different fibrous cartilages, some being composed almost entirely of fibres with few and small interstices, as the interarticular cartilages, while others exhibit large spaces filled with an imperfect fibrous tissue and cells, as the intervertebral substance. The fibrous cartilages admit of arrangement into four groups, namely, interarticular, stratiform, interosseus, and free. The in- stances of interarticular fibrous cartilages (menisci) are those of the lower jaw, sternal and acromial end of the clavicle, wrist, carpus, knee, to which may be added the fibrous cartilages of circumference, glenoid and cotyloid. The stratiform fibrous cartilages are such as form a thin coating to the grooves on bone through which tendons play. The interosseous fibrous cartilages are the intervertebral sub- stance and symphysis pubis. The free fibrous cartilages are the tarsal cartilages of the eyelids. * A portion of fibrous cartilage. The section is taken fr i pubis, und tuapnified 155 ag e section is taken from the symphysis YELLOW FIBROUS TISSUE. 115 The development of cartilage is the same with that of cartilage of bone (page 5), the different forms of cartilage resulting from subse- quent changes in the intercellular substance and cells. -Thus, for example, in articular cartilage the cells undergo the lowest degree of development, are very disproportionate to the intercellular substance, and the latter remains permanently structureless, In reticular carti- lage the cells possess a more active growth, and surpass in bulk the intercellular substance, while the latter is composed also of cells, which assume a fibrous disposition. In fibrous cartilage development is most energetic in the intercellular substance ; this is converted into fasciculi of fibrous tissue while the interspaces are filled with cells and imperfect fibrous tissue in every stage of development. Frsrous TissvE is one of the most generally distributed of all the animal tissues ; it is composed of fibres of extreme minuteness, and presents itself under three elementary forms ; namely, white fibrous tissue, yellow fibrous tissue, and red fibrous tissue. In white fibrous tissue the fibres are cylindrical, exceedingly minute, (about +s3gp of an inch in diameter), transparent and undulating ; they are collected into small fasciculi (from ggg to zphg5 of an inch) and these latter form larger fasciculi, which according to their arrangement give rise to the production of thin laminze, membranes, ligamentous bands, and tendinous cords. The connecting medium of the fibres in the formation of the primitive fasciculi is a transparent structureless interfibrous substance or blastema, to which in most situations are added numerous minute dark filaments derived from nuclei and thence termed nuclear filaments. The nuclear filaments are sometimes wound spirally around the fasciculi or interlace with their separate fibres, at other times they are variously twisted. and run parallel with the fasciculi. The fasciculi are connected and held to- gether in the formation of membranes and cords by loose fibres which are interwoven between them, or by mutual interlacement. Examples of white fibrous tissue are met with in three principal forms, namely, membrane, ligament, and tendon. The membranous form of white fibrous tissue is seen in the common connecting medium of the body, namely, fibro-cellular or areolar tissue, in which the membrane is extremely thin and disposed in lamina, bands or threads, leaving interstices of various size between them. It is seen also in the condensed covering of various organs, as the periosteum, perichondrium, capsule propriz of glands, membranes of the brain, sclerotic coat of the eyeball, pericardium, fasciz ; sheaths of muscles, tendons, vessels; nerves and ducts; sheaths of the erectile organs, and the corium of the dermic and mucous membrane. Ligament is the name given to those bands of various breadth and thickness which retain the articular ends of bones in contact in the construction of joints. They are glistening and inelastic and com- posed of fasciculi of fibrous tissue ranged in a parallel direction side by side, or in some situations interwoven with each other. The fasciculi are held together by separate fibres, or by areolar tissue. 116 ADIPOSE TISSUE.—SYNOVIAL MEMBRANE. Tendon is the collection of parallel fasciculi of fibrous tissue, by means of which muscles are attached to bones. They are constructed on the same principle with ligaments, are usually rounded in their figure, but in some instances are spread out so as to assume a membranous form. In the latter state they are called aponeuroses. Yellow fibrous tissue is known also by the appellation elastic tissue, from one of its more prominent physical properties, a property which permits of its fibres being drawn out to double their length and again returning to their original dimensions. The fibres of elastic tissue are transparent, brittle, flat, or polyhedral in shape, colourless when single but yellowish in an aggregated form, and considerably thicker (s¢55 of an inch in diameter) than the fibres of white fibrous tissue. In the construction of their peculiar tissue they communicate with each other by means of short oblique fibres, which unite with adjoining fibres at acute or obtuse angles without any enlargement of the fibre with which they are joined. This circumstance has given rise to the idea of these fibres giving off branches, an expression derived from the division of blood-vessels, and another term borrowed from the same source has been applied to their communication with each other, namely, inosculation ; but both these expressions in their literal meaning are incorrect. When yellow fibrous tissue is cut or torn, the fibres in consequence of their elasticity become clubbed and curved at the extremity, a striking character of this tissue. The instances of yellow fibrous tissue are ; the ligamenta subflava of the arches of the vertebra, chord vocales, thyro-epiglottic liga- ment, crico-thyroidean membrane, the membranous layers connecting the cartilaginous rings of the trachea and bronchial tubes, the capsula propria of the spleen and the middle coat of arteries. It is also met with around some parts of the alimentary canal, as the cesophagus, cardia, and anus, around the male and female urethra, in the fascia lata, and in ses Hovis of the skin. Red fibrous tissue is also termed contractile tissue, from a peculiar property which it possesses, and which places it physiologically in an intermediate position between white fibrous tissue and muscular fibre. Its fibres are cylindrical, transparent, reddish in hue, and collected into fasciculi. It is met with in the corium of the skin, in the dartos, around the nipple, in the excretory ducts of glands, in the coats of blood-vessels, particularly veins, in the iris, in the inter- vascular spaces of the erectile tissue of the penis and clitoris, around the urethra, and around the vagina. ApiPosE Tissvuz is composed of minute cells, aggregated together in clusters of various size within the areole of fibro-cellular tissue. The cells of adipose tissue are identical in manner of formation with other cells, being developed on nuclei and increasing in size by the forma- tion of fluid in their interior. In adipose cells this fluid, instead of being albuminous as in other cells, is oleaginous, the oil at first appear- ing in separate globules, which subsequently coalesce into a single drop.. The size of adipose cells at their full development is about LIGAMENTS OF THE TRUNK. 117 7a Of an inch in diameter ; when isolated they are globular in form, but are hexagonal or polyhedral when compressed. They are per- fectly transparent, the cell-membrane being structureless and their nucleus disappearing as they attain their full size. SynoviaL MempraNz is a thin membranous layer, which invests the articular cartilages of the bones, and is thence reflected upon the surfaces of the ligaments which surround and enter into the composi- tion of a joint. It resembles the serous membranes in being a shut sac, and secretes a transparent and viscous fluid, which is named synovia. Synovia is an alkaline secretion, containing albumen, which is coagulable at a boiling temperature. The continuation of this mem- brane over the surface of the articular cartilage, a much agitated question, has been decided by the interesting discoveries of Henle, who has ascertained the existence of an epithelium upon cartilage identical with that produced by the reflected portion of the membrane. In some of the joints the synovial membrane is pressed into the articular cavity by a cushion of fat: this mass was called by Havers the synovial gland, from an incorrect supposition that it was the source of the synovia ; it is found in the hip and in the knee-joint. In the knee-joint, moreover, the synovial membrane forms folds, which are most improperly named ligaments, as the mucous and alar liga- ments, the two latter being an appendage to the cushion of fat. Besides the synovial membranes entering into the composition of joints, there are numerous smaller sacs of a similar kind interposed between surfaces which move upon each other so as to cause friction ; they are often associated with the articulations. These are the burse mucos@ ; they are shut sacs, analogous in structure to synovial mem- branes, and secreting a similar synovial fluid. The epithelium of synovial membranes is of the kind termed tesselated ; it is developed in the same manner with the epithelium of other free surfaces, and is continually reproduced from beneath, while the superficial layers are being rubbed off and lost. ARTICULATIONS, The joints may be arranged, according to a natural division, into those of the trunk, those of the upper extremity, and those of the lower extremity. LIGAMENTS OF THE TRuNK.—The articulations of the trunk are divisible into ten groups, viz.— 1. Of the vertebral column. _ 2. Of the atlas, with the occipital bone. 3. Of the axis, with the occipital bone. 4. Of the atlas, with the axis. 5. Of the lower jaw. 118 LIGAMENTS OF THE VERTEBRAL COLUMN. 6. Of the ribs, with the vertebre. 7. Of the ribs, with the sternum, and with each other. -8. Of the sternum. 9. Of the vertebral column, with the pelvis. 10. Of the pelvis. 1. Articulation of the vertebral Column.—The ligaments connecting together the different pieces of the vertebral column, admit of the same arrangement with that of the vertebre themselves. Thus the ligaments Of the bodies are the— Anterior common ligament, Posterior common ligament, Intervertebral substance. Of the arches,— Ligamenta subflava. Of the articular processes,— Capsular ligaments, Synovial membranes, Of the spinous processes,— — Inter-spinous, Supra-spinous. Of the transverse processes,— Inter-transverse. Bopirres —The Anterior common ligament is a broad and riband- ~ like band of ligamentous fibres, extending along the front surface of the vertebral column, from the axis to the sacrum. It is intimately connected with the intervertebral substances, and less closely with the bodies of the vertebrae. In the dorsal region it is thicker than-in the ~ cervical and lumbar, and consists of a median and two lateral portions separated from each other by a series of openings for the passage of Fig. 50.* * The anterior ligaments of the vertebrae, and ligaments of the ribs. 1. The anterior common ligament. 2. The anterior costo-vertebral or stellate ligament. 3. The anterior costo-transverse ligament. 4. The interarticular ligament con- necting the head of the rib to the intervertebral substance, and separating the two synovial membranes of this articulation. LIGAMENTS OF THE VERTEBRAL COLUMN. 119 vessels. The ligament is composed of fibres of various length closely interwoven with each other; the deeper and shorter crossing the inter- vertebral substances from one vertebra to the next; and the superficial and longer fibres crossing three or four vertebree. The anterior common ligament is in relation by its postertor or ver- tebral surface, with the intervertebral substances, the bodies of the vertebree, and with the vessels, principally veins, which. separate its central from its lateral portions. By its anterior or visceral surface it is in relation in the neck, with the longus ? ‘ colli muscles, the pharynx and the cesopha- Hig. 61. gus; in the thoracic region, with the aorta, the venz azygos, and thoracic duct; and in the lumbar region, with the aorta, right renal artery, right lumbar arteries, arteria sacra media, vena cava inferior, left lumbar veins, receptaculum chyli, the commence- ment of the thoracic duct, and the tendons of the lesser muscle of the diaphragm with the fibres of which the ligamentous fibres interlace. The Posterior common ligament lies upon the posterior surface of the bodies of the _vertebre, and extends from the axis to the sacrum. It is broad opposite the inter- vertebral substances, to which it is closely adherent; and narrow and thick over the bodies of the vertebrae, from which it is separated by the veins of the base of the vertebrae. It is composed like the anterior ligament of shorter and longer fibres which are disposed in a similar manner. The posterior common ligament is in relation by its anterior surface with the intervertebral substances, the bodies of the vertebra, and with the venze basum vertebrarum ; and by its posterior surface with the dura mater of the spinal cord, some loose areolar tissue and numerous small veins being interposed. The Intervertebral substance is a lenticular disc of fibrous cartilage, interposed between each of the vertebree from the axis to the sacrum, and retaining them firmly in connexion with each other. It differs in thickness in different parts of the column, and varies in depth at different points of its extent; thus, it is thickest in the lumbar re- gion, deepest in front in the cervical and lumbar regions, and behind in the dorsal region ; and contributes, in a great measure, to the formation of the natural curves of the vertebral column. * A posterior view of the bodies of three dorsal vertebree, connected by their intervertebral substance 1, 1. The laminz (2) have been sawn through near the bodies of the vertebrze, and the arches and processes removed, in order to shew (3) the posterior common ligament. A part of one of the openings in the posterior surface of the vertebra, for the transmission of the vena basis 120 LIGAMENTS OF THE VERTEBRAL COLUMN. When the intervertebral substance is bisected either horizontally or vertically, it is seen to be composed of a series of layers of dense fibrous tissue, separated by interstices filled with the softer kind. The central part of each intervertebral disc is wholly made up of this softer fibrous cartilage, which has the appearance of a pulp, and is so elastic as to rise above the level of the section as soon as its division is completed. When examined from the front, the layers are found to consist of fibres passing ob- Fig. 52." liquely between the two verte- bree, in one layer passing from left to right, in the next from right to left, alternating in each successive layer. Arcnes. — The ligamenta subflava are two thin planes, of yellow fibrous tissue, situa- ted between the arches of each pair of vertebrae, from the axis to the sacrum. From the im- bricated position of the laminze they are attached to the poste- rior surface of the vertebra be- low, and to the anterior sur- face of the arch of the vertebra above, and are separated from each other at the middle line by a slight interspace. They-coun- teract, by their elasticity, the efforts of the flexor muscles of the trunk ; and by preserving the upright position of the spine, limit the expenditure of muscular force. They are longer in the cervical than in the other regions of the spine, and are thickest in the lumbar region, The ligamenta subflava.are in relation by both surfaces with the meningo-rachidian veins, and internally they are separated from the dura mater of the spinal cord by those veins and some loose areolar and adipose tissue. ARTICULAR PROCESSES.—The ligaments of the articular processes of the vertebree are loose synovial capsules which surround the articu- lating surfaces. They are protected on their external side by a thin layer of ligamentous fibres. Sprnous PROcEssES. — The inéer-spinous ligaments are thin and membranous, and are extended between the spinous processes in the dorsal and lumbar regions. They are thickest in the latter region ; and are in relation with the multifidus spinze muscle at each side. —, is seen at 4, by the side of the narrow and unattached portion of the gament. * An internal view of the arches of three vertebrae. To obtain this view the laminz have been divided through their pedicles. 1. One of the ligamenta subflava. 2. The capsular ligament of one side. LIGAMENTS OF THE VERTEBRAL COLUMN. 121 The Supra-spinous ligament (fig. 60) is a strong and inelastic fibrous cord, which extends from the apex of the spinous process of the last cervical vertebra to the sacrum, being attached to each spinous process in its course ; it is thickest in the lumbar region. The continuation of this ligament upwards to the tuberosity of the occipital bone, con- Fig. 53.* stitutes the rudimentary ligamentum nuche of man. The latter is strengthened, as in animals, by a thin slip from the spinous process of each of the cervical vertebra. TRANSVERSE PROCESSES.—The inter-transverse ligaments are thin and membranous ; they are found only between the transverse pro- cesses of the lower dorsal vertebre. 2. Articulation of the Atlas with the Occipital bone.—The ligaments of this articulation are seven in number,— Two anterior occipito-atloid, Posterior occipito-atloid, Lateral occipito-atloid, " Two capsular. Of the two anterior ligaments one is a rounded cord, situated in the middle line, and superficially to the other. It is attached above, to * An anterior view of the ligaments connecting the atlas, the axis, and the occipital bone. A transverse section has been carried through the base of the skull, dividing the basilar process of the occipital bone and the petrous portions of the temporal bones. 1. The anterior round occipito-atloid ligament. 2. The anterior broad occipito-atloid ligament. 3. The commencement of the anterior common ligament. 4. The anterior atlo-axoid ligament, which is continuous inferiorly with the commencement of the anterior common ligament. 5. One of the atlo-axoid capsular ligaments ; the one on the opposite side has been removed, to shew the approximated surfaces of the articular processes (6). 7. One of the occipito-atloid capsular ligaments. The most external of these fibres constitute the lateral occipito-atloid ligament. ]22 LIGAMENTS OF THE VERTEBRAL COLUMN. the basilar process of the occipital bone ; and below, to the anterior tubercle of the atlas. The deeper ligament is a broad membranous layer, attached above, to the margin of the occipital foramen ; and below, to the whole length of the anterior arch of the atlas. It is in relation in front with the recti antici minores and behind with the odontoid ligaments. The posterior ligament is thin and membranous; it is attached above, to the margin of the occipital foramen ; and below, to the pos- terior arch of the atlas. It is closely adherent to the dura mater, by its inner surface ; and forms a ligamentous arch at each side, for the passage of the vertebral arteries and first cervical nerves. It is in Fig 54.* relation posteriorly with the recti postici minores and obliqui supe- riores. The lateral ligaments are strong fasciculi of ligamentous fibres, at- tached below, to the base of the transverse process of the atlas at each side, and above to the transverse process of the occipital bone. With a ligamentous expansion derived from the vaginal process of the tem- poral bone, these ligaments form a strong sheath around the vessels and nerves which pass through the carotid and jugular foramina. The capsular ligaments are the thin and loose ligamentous capsules, which surround the synovial membranes of the articulations between the condyles of the occipital bone and the superior articular processes of the atlas. The ligamentous fibres are most numerous upon the anterior and external part of the articulation. * The posterior ligaments of the occipito-atloid, and atlo-axoid articulations. 1, The atlas. 2. The axis. 3. The posterior ligament of the occipito-atloid articulation. 4,4, The capsular and lateral ligaments of this articulation. 5. The posterior ligament of the atlo-axoid articulation. 6, 6. Its capsular ligaments. 7. The first of the ligamenta subflava passing between the axis and the third cervical vertebra. 8, 8. The capsular ligaments of those vertebre. LIGAMENTS OF THE VERTEBRAL COLUMN. 123 The movements taking place between the cranium and atlas, are those of flexion and erection, giving rise to the forward nodding of the head. When this motion is increased to any extent the whole of the cervical region concurs in its production. 3. Articulation of the Axis with the Occipital bone.—The ligaments of this articulation are three in number,— Occipito-axoid, Two odontoid. The oceipito-axoid ligament (apparatus ligamentosus colli) is a broad band, which covers in the odontoid process and its ligaments. It is attached below to the body of the axis, where it is continuous with the posterior common ligament ; superiorly it is inserted by a broad Fig. 55.* expansion, into the basilar groove of the occipital bone. It is firmly connected opposite the body of the axis, with the dura mater; and sometimes is described as consisting of a central and two lateral por- tions ; this however is an unnecessary refinement. The odontoid ligaments (alar) are two short and thick fasciculi of fibres, which pass outwards from the apex of the odontoid process, to the sides of the occipital foramen and condyles. A third and smaller fasciculus (ligamentum suspensorium) proceeds from the apex of the odontoid process to the anterior margin of the foramen magnum. These ligaments serve to limit the extent to which rotation of the head may be carried, hence they are termed check ligaments. * The upper part of the vertebral canal, opened from behind in order to shew the occipito-axoid ligament. 1. The basilar portion of the sphenoid bone. 2. Section of the occipital bone. 3. The atlas, its posterior arch removed. 4. The axis, the posterior arch also removed. 5. The occipito-axoid ligament, rendered prominent at its middle by the projection of the odontoid process. 6. Lateral and capsular ligament of the occipito-atloid articulation. 7. Cap- sular ligament between the articulating processes of the atlas and axis. 124 LIGAMENTS OF THE LOWER JAW. 4, Articulation of the Atlas with the Awis.—The ligaments of this articulation are five in number,— Anterior atlo-axoid, Two capsular, Posterior atlo-axoid, Transverse. The anterior ligament consists of ligamentous fibres, which pass from the anterior tubercle and arch of the atlas to the base of the odontoid process and body of the axis, where they are continuous with the commencement of the anterior common ligament. The posterior ligament is a thin and membranous layer, passing be- tween the posterior arch of the atlas and the laminz of the axis, The capsular ligaments surround the articular processes of the atlas and axis ; they are loose, to permit of the freedom of movement which subsists between these vertebra. The ligamentous fibres are most Fig. 56.* i lie Hh numerous on the outer and anterior part of the articulation, and the synovial membrane usually communicates with the synovial cavity between the transverse ligament and the odontoid process. The transverse ligament is a strong ligamentous band, which arches across the area of the ring of the atlas from a rough tubercle upon the inner surface of one articular process to a similar tubercle on the other. It serves to retain the odontoid process of the axis, in connection with the anterior arch of the atlas. As it crosses the odontoid process, * A posterior view of the ligaments connecting the atlas, the axis, and the occipital bone. The posterior part of the occipital bone has been sawn away, and the arches of the atlas and axis removed. 1. The superior part of the occipito-axoid ligament, which has been cut away in order to shew the li ments beneath. 2. The transverse ligament of the atlas. 3,4, The ascending and descending slips of the transverse ligament, which have obtained for it the title of cruciform ligament. 5. One of the odontoid ligaments; the fellow ligament is seen on the opposite side. 6. One of the occipito-atloid capsular ligaments. 7. One of the atlo-axoid capsular ligaments. LIGAMENTS OF THE LOWER JAW. 125 some fibres are sent downwards to be attached to the body of the axis, and others pass upwards to be inserted into the basilar pro- cess of the occipital bone ; hence the ligament has a cross-like appear- ance, and has been denominated cruciform. A synovial membrane is situated between the transverse ligament and the odontoid process ; and another between that process and the inner surface of the anterior arch of the atlas. Actions.—It is the peculiar disposition of this ligament in relation to the odontoid process, that enables the atlas, and with it the entire cranium, to rotate upon the axis; the perfect freedom of movement between these bones being ensured by the two synovial membranes, The lower part of the ring, formed by the transverse ligament with the atlas, is smaller than the upper, while the summit of the odontoid process is larger than its base ; so that the process is still retained in its position by the transverse ligament, when the other ligaments are cut through. The extent to which the rotation of the head upon the axis can be carried is determined by the odontoid ligaments. The odontoid process with its ligaments is covered in by the occipito-axoid ligament. 5. Articulation of the Lower Jaw.—The lower jaw has properly but one ligament, the eaternal lateral; the ligaments usually described are three in number; to which may be added, as appertaining to the ‘mechanism of the joint, an interarticular fibrous-cartilage, and two synovial membranes,— External lateral, Internal lateral, Capsular. Interarticular fibrous-cartilage, Two synovial membranes. Fig. 57.* * An external view of the articulation of the lower jaw. 1. The zygomatic arch. 2. The tubercle of the zygoma. 3. The ramus of the lower jaw. 4. The mastoid portion of the temporal bone. 5. The external lateral ligament. 6. The stylo-maxillary ligament. 126 LIGAMENTS OF THE LOWER JAW. The external lateral ligament is a short and thick band of fibres, passing obliquely backwards from the tubercle of the zygoma, to the external surface of the neck of the lower jaw. It is in relation, ex- ternally with the integument of the face, and internally with the two synovial membranes of the articulation and the interarticular cartilage. The external lateral ligament acts conjointly with its fellow of the op- posite side of the head in the movements of the jaw. The internal lateral ligament has no connection with the articulation of the lower jaw, and is incorrectly named in relation to the joint ; it is a thin aponeurotic expansion extending from the extremity of the spinous process of the sphenoid bone to the margin of the dental fora- men. It is pierced at its insertion, by the mylo-hyoidean nerve. A triangular space is left between the internal lateral ligament and the neck of the jaw, in which are situated the internal maxillary artery and auricular nerve, the inferior dental artery and nerve, and a part of the external pterygoid muscle ; internally it is in relation with the internal pterygoid muscle. The capsular ligament consists of a few irregular ligamentous fibres, Fig. 58.* which pass from the edge of the glenoid cavity to the neck of the lower jaw, upon the inner and posterior side of the articulation. These fibres scarcely deserve consideration as a distinct ligament. The interarticular fibrous cartilage is a thin oval plate, thicker at the edges than in the centre, and placed horizontally between the head of the condyle of the lower jaw and the glenoid cavity. It is connected * An internal view of the articulation of the lower jaw. 1. A section through the petrous portion of the temporal bone and spinous process of the sphenoid. 2. An internal view of the ramus, and part of the y of the lower me 3. The internal portion of the capsular ligament. 4. The internal lateral gament. 5, A small interval at its insertion through which the mylo-hyoidean eere passes. 6. The stylo-maxillary ligament, a process of the deep cervical fascia. a LIGAMENTS OF THE RIBS. 127 by its outer border with the external lateral ligament, and in front re- ceives some fibres of insertion of the external pterygoid muscle. Oc- casionally it is incomplete in the centre. It divides the joint into two distinct cavities, the one being above and the other below the carti- lage. The synovial membranes are situated the one above, the other below the fibrous-cartilage, the former being the larger of the two. When the fibrous-cartilage is perforate, the synovial membranes communi- cate. Besides the lower jaw, there are several other joints provided with a complete interarticular cartilage, and, consequently, with two syno- vial membranes ; they are, the sterno-clavicular articulation, the acro- mio-cluvicular and the articulation of the ulna with the cuneiform bone. The interarticular fibrous-cartilages of the knee-joint are partial, and there is but one synovial membrane. The articulations of the heads of the ribs with the vertebra have two synovial membranes, separated by an interarticular ligament with- out fibrous-cartilage. Fig. 59.* Actions.—The movements of the lower jaw are depression, by which the mouth is opened ; elevation, by which it is closed ; a forward and backward movement, and a movement from side to side. In the movement of depression the interarticular cartilage glides for- * In this sketch a section has been carried through the joint, in order to shew the natural position of the interarticular fibro-cartilage, and the manner in which it is adapted to the difference of form of the articulating surfaces. 1. The glenoid fossa. 2. The eminentia articularis. 3. The interarticular fibro- cartilage. 4. The sie synovial cavity. 5. The inferior synovial cavity. 6. An interarticular fibro-cartilage, removed from the joint, in order to shew its oval and concave form ; it is seen from below. 128 LIGAMENTS OF THE RIBS. wards on the eminentia articularis, carrying with it the condyle. If this movement be carried too far, the superior synovial membrane is ruptured, and dislocation of the fibro-cartilage with its condyle into the zygomatic fossa occurs. In elevation the fibrous cartilage and con- dyle are returned to their original position. The forward and back- ward movement is a gliding of the fibro-cartilage upon the glenoid articular surface, in the antero-posterior direction ; and the movement from side to side, in the lateral direction. 6. Articulation of the Ribs with the Vertebre.—The ligaments of these articulations are so strong as to render dislocation impossible, the neck of the rib would break before displacement could occur ; they are divisible into two groups:—1l. Those connecting the head of the rib with the bodies of the vertebre ; and, 2. Those connecting the neck and tubercle of the rib with the transverse processes. They are lst Group. Anterior costo-vertebral or stellate, Capsular, Interarticular ligament, Two synovial membranes. 2nd Group. Anterior costo-transverse, Middle costo-transverse, Posterior costo-transverse. The anterior costo-vertebral or stellate ligament (fig. 50) consists of three short bands of ligamentous fibres that radiate from the anterior part of the head of the rib. The superior band passes upwards, and is attached to the vertebra above; the middle fasciculus is attached to the intervertebral substance ; and the inferior, to the vertebra below. In the first, eleventh, and twelfth ribs, the three fasciculi are attached to the body of the corresponding vertebra. The capsular ligament is a thin layer of ligamentous fibres surround- ing the joint in the interval left by the anterior ligament ; it is thick- est above and below the articulation, and protects the synovial mem- branes. The interarticular ligament is a thin band which passes between the sharp crest on the head of the rib and the intervertebral substance. It divides the joint into two cavities, which are each furnished with a separate synovial membrane. The first, eleventh, and twelfth ribs have » interarticular ligament, and consequently but one synovial mem- rane, The anterior costo-transverse ligament is a broad band composed of several fasciculi, which ascend from the crest-like ridge on the neck of the rib, to the transverse process immediately above. This ligament LIGAMENTS OF THE RIBS, 129 separates. the anterior from the posterior branch of the intercostal nerves. The middle costo-transverse ligament is a very strong interosseous ligament passing directly between the posterior surface of the neck of the rib, and the transverse process against which it rests. The posterior costo-transverse ligament is a small but strong fascicu- lus, passing obliquely from the tubercle of the rib, to the apex of the transverse process. The articulation between the tubercle of the rib and the transverse process is provided with a small synovial mem- brane. There is no anterior costo-transverse ligament to the first rib ; and only rudimentary posterior costo-transverse ligaments to the eleventh and twefth ribs. Actions.—The movements permitted by the articulations of the ribs, are wpwards and down- wards, and slightly forwards and backwards ; the movement increasing in extent from the head to the extremity of the — rib. The forward and back- =— 3 ™ ward movement is very trifling ) in the seven superior, but great- er in the inferior ribs; the eleventh and twelfth are very movable. 7. Articulation of the Ribs with the Sternum, and with each other.—The ligaments of the costo-sternal articulations are,— Fig. 60 * Anterior costo-sternal, Posterior costo-sternal, Superior costo-sternal, Inferior costo-sternal, Synoyial membranes. The anterior costo-sternal ligament is a thin band of ligamentous fibres, that passes in a radiated direction from the extremity of the costal cartilage to the anterior surface of the sternum, and intermingles its fibres with those of the ligament of the opposite side and with the tendinous fibres of origin of the pectoralis major muscle. The posterior costo-sternal ligament is much smaller than the ante- rior, and consists only of a thin fasciculus of fibres situated on the posterior surface of the articulation. * A posterior view of a part of the thoracic portion of the vertebral column, shewing the ligaments connecting the vertebree with each other and the ribs with the vertebrze. 1, 1. The supra-spinous ligament. 2, 2. The ligamenta subflava, connecting the laminz. 3. The anterior costo-transverse ligament. 4, The posterior costo-transverse ligaments. K 130 LIGAMENTS OF THE PELVIS. The superior and inferior costo-sternal ligaments are narrow fasciculi corresponding with the breadth of the cartilage, and connecting its superior and inferior border with the side of the sternum. The synovial membrane is absent in the articulation of the first rib, its cartilage being usually continuous with the sternum ; that of the second rib has an inter-articular ligament, with two synovial mem- branes. The sath and seventh ribs have several fasciculi of strong ligament- ous fibres, passing from the extremity of their cartilages to the anterior surface of the ensiform cartilage, which latter they are intended to support. They are named the costo-ayphoid ligaments. The siath, seventh, and eighth, and sometimes the fifth and the ninth costal cartilages, have articulations with each other, and a perfect synovial membrane. They are connected by ligamentous fibres which pass from one cartilage to the other, eaternal and internal ligaments. The ninth and tenth are connected at their extremities by ligament- ous fibres, but have no synovial membranes. Actions.—The movements of the costo-sternal articulations are very trifling ; they are limited to a slight sliding motion. The first rib is the least, and the second the most movable. 8. Articulation of the Sternum.—The pieces of the sternum ‘are connected by means of a thin plate of interosseous cartilage placed be- tween each, and by an anterior and posterior ligament. The fibres of the anterior sternal ligament are longitudinal in direction, but so blended with the anterior costo-sternal ligaments, and the tendinous fibres of origin of the pectoral muscles as scarcely to be distinguished as a distinct ligament. The posterior sternal ligament is a broad smooth plane of longitudinal fibres, placed upon the posterior surface of the bone, and extending from the manubriun to the ensiform car- tilage. These ligaments contribute very materially to the strength of the sternum and to the elasticity of the front of the chest. 9. Articulation of the Vertebral Column with the Pelvis.—The last lumbar vertebra is connected with the sacrum by the same ligaments with which the various vertebre are connected to each other ; viz. the anterior and posterior common ligaments, intervertebral substance, ligamenta subflava, capsular ligaments, and inter and supra-spinous ligaments. There are, however, éwo proper ligaments connecting the vertebral column with the pelvis ; these are, the Lumbo-sacral, Lumbo-iliac. The lumbo-sacral ligament is a thick triangular fasciculus of ligament- ous fibres, connected above, with the transverse process of the last lumbar vertebra ; and below with the posterior part of the upper border of the sacrum. The /umbo-iliae ligament passes from the apex of the transverse process of the last lumbar vertebra to that part of the crest of the LIGAMENTS OF THE PELVIS. 131 ilium which surmounts the sacro-iliac articulation. It is triangular in form. 10. The Articulations of the Pelvis.—The ligaments belonging to the articulations of the pelvis are divisible into four groups :—1. Those connecting the sacrum and ilium; 2. those passing between the sacrum and ischium ; 3. between the sacrum and coccyx ; and 4, be- tween the two pubic bones. Ist, Between the sacrum and ilium. Sacro-iliac anterior, Sacro-iliac posterior. 2nd, Between the sacrum and ischium. Sacro-ischiatic anterior (short), Sacro-ischiatic posterior (Jong). 3rd, Between the sacrum and coccyzx. Sacro-coccygean anterior, Sacro-coccygean posterior. 4th, Between the ossa pubis. Anterior pubic, Posterior pubic, Superior pubic, Sub-pubic, Interosseous fibro-cartilage. 1, Between the Sacrum and Ilium.—The anterior sacro-iliae liga- ment consists of numerous short ligamentous fibres, which pass from bone to bone on the anterior surface of the joint. The posterior sacro-iliae or interosseous ligament is composed of nu- merous strong fasciculi of ligamentous fibres, which pass horizontally between the rough surfaces in the posterior half of the sacro-iliac arti- culation, and constitute the principal bond of connection between the sacrum and the ilium. One fasciculus of this ligament, longer and larger than the rest, is distinguished from its direction, by the name of the oblique sacro-iliac ligament. It is attached, by one extremity, to the posterior superior spine of the ilium ; and, by the other, to the third transverse tubercle on the posterior surface of the sacrum. The surfaces of the two bones forming the sacro-iliac articulation, are partly covered with cartilage, and partly rough and connected by the interosseous ligament. The anterior or auricular half is coated with cartilage, which is thicker on the sacrum than on the ilium. _The sur- face of the cartilage is irregular, and provided with a very delicate synovial membrane, which cannot be demonstrated in the adult ; but is apparent in the young subject, and in the female during pregnancy. 2. Between the Sacrum and Ischium.—The anterior or lesser sacro- ischiatic ligament is thin, and triangular in form ; it is attached by its apex to the spine of the ischium ; and by its broad extremity to the 132 LIGAMENTS OF THE PELVIS. Fig. 61.* side of the sacrum and coccyx, interlacing its fibres with the greater sacro-ischiatic ligament. The anterior sacro-ischiatic ligament i is in relation in front with the coccygeus muscle, and behind with the posterior ligament, with which its fibres are intermingled. By its upper border it forms a part of the lower boundary of the great sacro-ischiatic foramen, and by the lower a part of the lesser sacro-ischiatic foramen. The posterior or greater sacro-ischiatic ligament, considerably larger, thicker, and more posterior than the preceding, is narrower in the middle than at each extremity. It is attached, by its smaller end, to the inner margin of the tuberosity and ramus of the ischium, where it forms a falciform process, which protects the internal pudic artery, and is continuous with the obturator fascia. By its larger extremity it is inserted into the side of the coccyx, sacrum, and posterior inferior spine of the ilium. The posterior sacro-ischiatic ligament is in relation in front with the anterior ligament, and behind with the gluteus maximus, to some of the fibres of which it gives origin. By its superior border it forms * The ligaments of the pelvis and hip-joint. 1. The lower part of the ante- rior common ligament of the vertebree, extending downwards over the front of the sacrum. 2. The lumbo-sacral ligament. 3. The lumbo-iliac ligament. 4. The anterior sacro-iliac ligaments. 5. The obturator membrane. 6. Pou- Ps "8 aoa 7. Gimbernat’s ligament. 8. The capsular ligament ‘of the ip-joint. 9. The ilio-femoral or accessory ligament. LIGAMENTS OF THE PELVIS. 133 part of the lesser ischiatic foramen, and by its lower border, a part of the boundary of the perineum. It is pierced by the coccygeal branch of the ischiatic artery. The two ligaments convert the sacro-ischiatic notches into foramina. 3. Between the Sacrum and Coccyx.—The anterior sacro-coccygean ligament is a thin fasciculus passing from the anterior surface of the sacrum to the front of the coccyx. The posterior sacro-coccygean ligament is a thick ligamentous layer, which completes the lower part of the sacral canal, and connects the sacrum with the coccyx posteriorly, extending as far as the apex of the latter bone. Between the two bones is a thin disc of soft fibrous cartilage. In females there is frequently a small synovial membrane. This articu- lation admits of a certain degree of movement backwards during par- turition. * Ligaments of the pelvis and hip-joint. The view is taken from the side. 1. The oblique sacro-iliac ligament. The other fasciculi of the posterior sacro- iliac ligaments are not seen in this view of the pelvis. 2. The posterior sacro- ischiatic ligament. 3. The anterior sacro-ischiatic ligament. 4. The great sacro-ischiatic foramen. 5. The lesser sacro-ischiatic foramen. 6. The coty- loid ligament of the acetabulum. 7. The ligamentum teres. 8. The cut edge of the capsular ligament, shewing its extent posteriorly as compared with its anterior attachment. 9. The obturator membrane only partly seen. 134 LIGAMENTS OF THE UPPER EXTREMITY. The ligaments connecting the different pieces of the coccyx consist of a few scattered anterior and posterior fibres, and a thin disc of inter- osseous cartilage ; they exist only in the young subject, in the adult the pieces become ossified. 4, Between the Ossa Pubis.—The anterior pubic ligament is com- posed of ligamentous fibres, which pass obliquely across the union of the two bones from side to side, and form an interlacement in front of the symphysis. The posterior pubic ligament consists of a few irregular fibres uniting the pubic bones posteriorly. The superior pubic ligament is a thick band of fibres connecting the angles of the pubic bones superiorly, and filling the inequalities upon the surface of the bones. The sub-pubic ligament is a thick arch of fibres connecting the two bones inferiorly, and forming the upper boundary of the pubic arch. The interosseous fibro-cartilage unites the two surfaces of the pubic bones, in the same manner as the intervertebral substance connects the bodies of the vertebrae. It resembles the intervertebral substance also in being composed of oblique fibres disposed in concentric layers, which are more dense towards the surface than near the centre. It is thick in front, and thin behind. A synovial membrane is some- times found in the posterior half of the articulation. This articulation becomes movable towards the latter term of preg- nancy, and admits of a slight degree of separation of its surfaces. The obturator ligament or membrane is not a ligament of articula- tion, but simply a tendino-fibrous membrane stretched across the ob- turator foramen. It gives attachment by its surfaces, to the two obtu- rator muscles, and leaves a space in the upper part of the foramen, for the passage of the obturator vessels and nerve. The numerous vacuities in the walls of the pelvis, and their closure by ligamentous structures, as in the case of the sacro-ischiatic fissures and obturator foramina, serve to diminish very materially the pressure on the soft parts during the passage of the head of the foetus through the pelvis in parturition. LIGAMENTS OF THE UPPER EXTREMITY. The Ligaments of the upper extremity may be arranged in the order of the articulations between the different bones ; they are, the - Sterno-clavicular articulation. . Scapulo-clavicular articulation. . Ligaments of the scapula. . Shoulder joint. . Elbow joint. . Radio-ulnar articulation. . Wrist joint. “TO Ore oN te a STERNO-CLAVICULAR LIGAMENTS. 135 8. Articulation between the carpal bones, 9. Carpo-metacarpal articulation. 10. Metacarpo-phalangeal articulation. 11. Articulation of the phalanges. 1. Sterno-clavicular Articulation.—The sterno-clavicular is an arthro- dial articulation ; its ligaments are, Anterior sterno-clavicular, Posterior sterno-clavicular, Inter-clavicular, Costo-clavicular (rhomboid), Interarticular fibro-cartilage, Two synovial membranes. The anterior sterno-clavicular ligament is a broad ligamentous layer, extending obliquely downwards and forwards, and covering the anterior aspect of the articulation. This ligament is im relation by its anterior surface with the integument and with the sternal origin of the sterno-mastoid muscle ; and behind with the interarticular fibro-carti- lage and synovial membranes. The posterior sterno-clavicular ligament is a broad fasciculus, cover- ing the posterior surface of the articulation. It is im relation by its anterior surface with the interarticular fibro-cartilage and synovial membranes, and behind with the sterno-hyoid muscle. The two ligaments are continuous at the upper and lower part of the articulation, so as to form a complete capsule around the joint. The tnter-clavicular ligament is a cord-like band which crosses from the extremity of one clavicle to the other, and is closely connected with the upper border of the sternum. It is separated by areolar tissue from the sterno-thyroid muscles. The costo-clavicular ligament (rhomboid) is a thick fasciculus of fibres, connecting the sternal extremity of the clavicle with the cartilage of the first rib. It is situated obliquely between the rib and the under surface of the clavicle. It is in relation in front with the tendon of origin of the subclavius muscie, and behind with the subclavian vein. Actions.—The movements of the sterno-clavicular articulation, are a gliding movement of the fibro-cartilage with the clavicle upon the arti- cular surface of the sternum in the directions forwards, backwards, up- wards, and downwards ; and circumduction. This articulation is the centre of the movements of the shoulder. It is the rupture of the rhomboid ligament in dislocation of the ster- nal end of the clavicle that gives rise to the deformity peculiar to this accident. The interarticular fibro-cartilage is nearly circular in form, and thicker at the edges than in the centre. It is attached above to the clavicle ; below to the cartilage of the first rib ; and throughout the rest of its circumference to the anterior and posterior sterno-clavicular 136 SCAPULO-CLAVICULAR LIGAMENTS, ligaments ; it divides the joint into two cavities, which are lined by distinct synovial membranes. This cartilage is sometimes pierced through its centre, and not unfrequently deficient, to a greater or less extent, in its lower part. 2. Scapulo-clavicular Articulation.—The ligaments of the scapular end of the clavicle are, the Superior acromio-clavicular, Inferior acromio-clavicular, Coraco-clavicular (¢rapezoid and conoid), Interarticular fibro-cartilage, Two synovial membranes. The superior acromio-clavicular ligament is a moderately thick plane of superimposed fibres passing between the extremity of the clavicle and the acromion, upon the upper surface of the joint. The inferior acromio-clavicular ligament is a thin plane situated upon the under surface. These two ligaments are continuous with each other in front anf behind, and form a complete capsule around the joint. The coraco-clavicular ligament (trapezoid, conoid) is a thick fasci- culus of ligamentous fibres, passing obliquely between the base of the coracoid process and the under surface of the clavicle, and holding the end of the clavicle in firm connection with the scapula. When seen from before, it has a quadrilateral form: hence it is named trapezoid ; and, examined from behind, it has a triangular form, the base being upwards ; hence another name, conoid. The interarticular fibro-cartilage is often indistinct, from having * The ligaments of the sterno-clavicular and costo-sternal articulations. 1. The anterior sterno-clavicular ligament. 2. The inter-clavicular ligament. 3. The costo-clavicular or rhomboid ligament, seen on both sides. 4. The interarticular fibro-cartilage, brought into view by the removal of the anterior and posterior ligaments. 5. The anterior costo-sternal ligaments of the first and second ribs. LIGAMENTS OF THE SCAPULA. 137 partial connections with the fibro-cartilaginous surfaces of the two bones between which it is placed, and not unfrequently absent. When partial, it occupies the upper part of the articulation. The synovial membranes are very delicate. There is, of course, but one, when the fibro-cartilage is incomplete. Fig. 64.* Actions.—The acromio-clavicular articulation admits of two move- ments, the gliding of the surfaces upon each other ; and the rotation of the scapula, upon the extremity of the clavicle. 3. The Proper ligaments of the Scapula are the Coraco-acromial, Transverse. The coraco-acromial ligament is a broad and thick triangular band, which forms a protecting arch over the shoulder joint. It is attached by its apex to the point of the acromion process, and by its base to the external border of the coracoid process its whole length. This ligament is in relation above with the under surface of the deltoid muscle; and below with the tendon of the supra-spinatus muscle, a bursa mucosa being usually interposed. * The ligaments of the ge and shoulder joint. 1. The superior acro- mio-clavicular ligament. 2. The coraco-clavicular ligament; this aspect of the ligament is named trapezoid. 3. The coraco-acromial ligamient. 4. The transverse ligament. 5. The capsular ligament. 6. The coraco-humeral ligament. 7. The long tendon of the biceps issuing from the capsular liga- ment, and entering the bicipital groove. 138 SHOULDER JOINT. The transverse or coracoid ligament is a narrow but strong fasciculus which crosses the notch in the upper border of the scapula, from the base of the coracoid process, and converts it Fig. 65.* into a foramen. The supra-scapular nerve passes through this foramen. 4, Shoulder Joint.— The scapulo-humeral articulation is an enarthrosis, or ball and socket joint—its ligaments are, the Capsular, Coraco-humeral, Glenoid. The capsular ligament completely encircles the articulating head of the scapula and the head of the humerus, and is attached to the neck of each bone. It is thick above, where resistance is most required, and is strength- ened by the tendons of the supra-spinatus, infra-spinatus, teres minor, and subscapularis muscles: below it is thin and loose. The capsule is incomplete at the point of contact with the tendons, so that they obtain upon their inner surface a covering of synovial mem- brane. The coraco-humeral ligament is a broad band which descends obliquely outwards from the border of the coracoid process to the greater tuberosity of the humerus,and serves to strength- en the superior and anterior part of the capsu- - lar ligament. The glenotd ligament is the prismoid band of fibro-cartilage, which is attached around the margin of the glenoid cavity for the purposes of protecting its edges, and deepening its cavity. It divides supe- riorly into two slips which are continuous with the long tendon of the biceps ; hence the ligament is frequently described as being formed by the splitting of that tendon. The cavity of the articulation is traversed by the long tendon of the biceps, which is enclosed in a sheath of synovial membrane in its passage through the joint. The synovial membrane of the shoulder joint is very extensive ; it communicates anteriorly through an opening in the capsular ligament with a large bursal sac, which lines the under surface of the tendon of the subscapularis muscle. Superiorly, it frequently communicates through another opening in the capsular ligament with a bursal sac _* An internal view of the ligaments of the elbow joint. 1. The anterior ligament. 2. The internal lateral ligament. 3. The orbicular ligament. 4. The oblique ligament. 5. The interosseous ligament. 6. The internal con- dyle of the humerus, which conceals the posterior ligament. \ a ve » it “s ELBOW JOINT. 139 belonging to the infra-spinatus muscle ; and it moreover forms a sheath around that portion of the tendon of the biceps, which is in- cluded within the joint. The muscles immediately surrounding the shoulder joint are the subscapularis, supra-spinatus, infra-spinatus, teres minor, long head of the triceps and deltoid ; the long tendon of the biceps is within the capsular ligament. Actions.—The shoulder joint is capable of every variety of motion, viz. of movement Fig. 66.* forwards and backwards, of abduction and ad- duction, of circumduction and rotation. 5. Elbow Joint.—The elbow is a ginglymoid articulation ; its ligaments are four in num- ber,— Anterior, Posterior, Internal lateral, External lateral. The anterior ligament is a broad and thin membranous layer, descending from the an- terior surface of the humerus, immediately above the joint, to the coronoid process of the ulna-and orbicular ligament. On each side it is connected with the lateral ligaments. It is composed of fibres which pass in three different directions, vertical, transverse, and oblique, the latter being extended from within outwards to the orbicular ligament, into which they are attached inferiorly. This ligament is covered in by the brachialis anticus muscle. The posterior ligament is a broad and loose layer passing between the posterior surface of the humerus and the anterior surface of the base of the olecranon, and connected at each side with the lateral ligaments. It is covered in by the tendon of the triceps. The internal lateral ligament is a thick tri- angular layer, attached above, by its apex, to the internal condyle of the humerus ; and be- low, by its expanded border, to the margin of the greater sigmoid cavity of the ulna, extending from the coronoid process to the olecra- non. At its insertion it is intermingled with some transverse fibres. * An external view of the elbow joint. 1. The humerus. 2. Theulna. 3. The radius. 4. The external lateral ligament inserted inferiorly into (5) the orbicular ligament. 6. The posterior extremity of the orbicular ligament, spreading out at its insertion into the ulna. 7. The anterior ligament, scarcely apparent in this view of the articulation. 8. The posterior ligament, thrown into folds by the extension of the joint. 140 ELBOW JOINT. The internal lateral ligament is in relation posteriorly with the ulnar nerve. __. The external lateral ligament is a strong and narrow band, which de- scends from the external condyle of the humerus, to be inserted into the orbicular ligament, and into the ridge on the ulna, with which the posterior part of the latter ligament is connected. This ligament is closely united with the tendon of origin of the supinator brevis muscle. The synovial membrane is extensive, and is reflected from the carti- laginous surfaces of the bones upon the inner surface of the ligaments. It surrounds inferiorly the head of the radius, and forms an articulat- ing sac between it and the lesser sigmoid notch. The muscles immediately surrounding, and in contact with, the elbow joint, are in front, the brachialis anticus ; to the inner side, the pronator radii teres, flexor sublimis digitorum, and flexor carpi ulnaris ; externally, the. extensor carpi radialis brevior, extensor communis digitorum, extensor carpi ulnaris, anconeus, and supinator brevis; and behind, the triceps. Actions.—The movements of the elbow joint are flexion and extension, which are performed with remarkable precision. The extent to which these movements are capable of being effected, is limited, in front by the coronoid process, and behind by the olecranon. 6. The Radio-ulnar Articulation—The radius and ulnar are firmly held together by ligaments which are connected with both extremities of the bones, and with the shaft ; they are, the Orbicular, Anterior inferior, Oblique, Posterior inferior, Interosseous, Interarticular fibro-cartilage. The orbicular ligament (annular, coronary) is a firm band several lines in breadth, which surrounds the head of the radius, and is attach- ed by each end to the extremities of the lesser sigmoid cavity. It is strongest behind where it receives the external lateral ligament, and is lined on its inner sarface by a reflection of the synovial membrane of the elbow joint. The rupture of this ligament permits of the dislocation of the head of the radius. The oblique ligament (called also ligamentum teres in contradistine- tion from the interosseous ligament) is a narrow slip of ligamentous fibres, descending obliquely from the base of the coronoid process of the ulna to the inner side of the radius, a little below its tuberosity. The interosseous ligament is a broad and thin plane of aponeurotic fibres passing obliquely downwards from the sharp ridge on the radius to that on the ulna. It is deficient superiorly, is broader in the middle than at each extremity, and is perforated at its lower part for the pas- sage of the anterior interosseous artery. The posterior interosseous artery passes backwards between the oblique ligament and the upper Pa a ee Lye WRIST JOINT. 141 border of the interosseous ligament. This ligament affords an exten- sive surface for the attachment of muscles. The interosseous ligament is ix relation, in front, with the flexor profundus digitorum, the flexor longus pollicis, and pronator quadratus muscle, and with the anterior interosseous artery and nerve ; and e- hind with the supinator brevis, extensor ossis metacarpi pollicis, ex- tensor primi internodii pollicis, extensor secundi internodii pollicis, and extensor indicis muscle, and near the wrist with the anterior inter- osseous artery and posterior interosseous nerve. The anterior inferior ligament is a thin fasciculus of fibres, passing transversely between the radius and ulna. The posterior inferior ligament is also thin and loose, and has the same disposition on the posterior surface of the articulation. The interarticular, or triangular fibro-cartilage, acts the part of a ligament between the lower extremities of the radius and ulna. It is attached by its apex to a depression on the inner surface of the styloid process of the ulna, and by its base to the edge of the radius. This fibro-cartilage is lined upon its upper surface by a synovial membrane, which forms a duplicature between the radius and ulna, and is called the membrana sacciformis. By its lower surface it enters into the ar- ticulation of the wrist-joint. Actions.—The movements taking place between the radius and the ulna are, the rotation of the former upon the latter ; rotation forwards being termed pronation, and rotation backwards supination. In these movements the head of the radius turns upon its own axis, within the orbicular ligament and the lesser sigmoid notch of the ulna ; while inferiorly the radius presents a concavity which moves upon the rounded head of the ulna. The movements of the radius are chiefly limited by the anterior and posterior inferior ligaments, hence these are not unfrequently ruptured in great muscular efforts. 7. Wrist Joint.—The wrist is a ginglymoid articulation ; the arti- cular surfaces entering into its formation being the radius and under surface of the triangular fibro-cartilage above, and the rounded surfaces of the scaphoid, semilunar, and cuneiform bone below ; its ligaments are four in number,— Anterior, Internal lateral, Posterior, External lateral. The anterior ligament is a broad and membranous layer consisting of three fasciculi, which pass between the lower part of the radius, and the scaphoid, semilunar, and cuneiform bone. The posterior ligament, also thin and loose, passes between the posterior surface of the radius, and the posterior surface of the semilunar and cuneiform bone. The internal lateral ligament extends from the styloid process of the ulna to the cuneiform and pisiform bone. The eaternal lateral ligament is attached by one extremity to the styloid process of the radius, and by the other to the side of the sca- 142 CARPAL ARTICULATIONS. phoid bone. The radial artery rests on this ligament as it passes back- wards to the first metacarpal space. The synovial membrane of the wrist joint lines the under surface of the radius and interarticular cartilage above, and the first row of bones of the carpus below. : The relations of the wrist 1 af} Fig. 67.* \ Wi sor tendons by which it is sur- rounded, and the radial and ul- nar artery. Actions.—The movements of the wrist joint are flexion, ea- tension, adduction, abduction, and circumduction. In these mo- tions the articular surfaces glide upon each other. ‘4 8. Articulations between the ys Carpal Bones.—These are am- phi-arthrodial joints, with the exception of the conjoined head \3 of the os magnum and .unci- ‘4. forme, which is received into a v1 cup formed by the scaphoid, y semilunar, and cuneiform bone, and constitutes an enarthrosis. The ligaments are, Interosseous fibro-cartilage, Anterior annular. The dorsal ligaments are ligamentous bands, that pass * The ligaments of the anterior aspect of the wrist and hand. 1. The lower part of the interosseous membrane. 2. The anterior inferior radio-ulnar liga- ment. 3. The anterior ligament of the wrist joint. 4. Its external lateral ligament. 5. Its internal lateral ligament. 6. The palmar ligaments of the carpus. 7. The pisiform bone, with its ligaments. 8. The ligaments con- necting the second range of carpal bones with the metacarpal, and the meta- carpal with each other. 9. The capsular ligament of the carpo-metacarpal ar- ticulation of the thumb. 10. Anterior ligament of the metacarpo-phalangeal articulation of the thumb. 11. One of the lateral ligaments of that articu- lation. 12. Anterior ligament of the metacarpo-phalangeal articulation of the index finger; this ligament has been removed in the other fingers. 13. Lateral ligaments of the same articulation; the corresponding ligaments are seen in the other articulations. 14. Transverse ligament connecting the heads of the metacarpal bones of the index and middle fingers; the same liga- ment is seen between the other fingers. 15 Anterior and one lateral liga- ment of the phalangeal articulation of the thumb. 16. Anterior and lateral ligaments of the phalangeal articulations of the index finger; the anterior ligaments are removed in the other fingers. joint are the flexor and exten-. ee See CARPAL. ARTICULATIONS. 143 transversely and longitudinally from bone to bone, upon the dorsal surface of the carpus. The palmar ligaments are fasciculi of the same kind, but stronger than the dorsal, having the like disposition upon the palmar surface. The interosseous ligaments are fibro-cartilaginous lamelle situated between the adjoining bones in each range: in the upper range they close the upper part of the spaces between the scaphoid, semilunar, and cuneiform bones ; in the lower range they are stronger than in the upper, and connect the os magnum on the one side to the unciforme, on the other to the trapezoides, and leave intervals through which the synovial membrane is continued to the bases of the metacarpal bones. The anterior annular ligament is a firm ligamentous band, which connects the bones of the two sides of the carpus. It is attached by one extremity to the trapezium and scaphoid, and by the other to the unciform process of the unciforme and the base of the pisiform bone, and forms an arch over the anterior surface of the carpus, beneath which the tendons of the long flexors and the median nerve pass into the palm of the hand. The articulation of the pisiform bone with the cuneiform, is pro- vided with a distinct synovial membrane, which is protected by fasci- culi of ligamentous fibres, forming a kind of capsule around the joint ; they are inserted into the cuneiforme, unciforme, and base of the metacarpal bone of the little finger. Synovial Membranes.—There are five synovial membranes entering into the composition of the articulations of the carpus :-— The first is situated between the lower end of the ulna and the in- terarticular fibro-cartilage ; it is called sacciform, from forming a sacculus between the lateral articulation of the ulna with the radius. The second is situated between the lower surface of the radius and_ interarticular fibro-cartilage aSove, and the first range of bones of the carpus below. The third is the most extensive of the synovial membranes of the wrist ; it is situated between the two rows of carpal bones, and passes between the bones of the second range, to invest the carpal extremities of the four metacarpal bones of the fingers. The fourth is the synovial membrane of the articulation of the me- tacarpal bone of the thumb with the trapezium. The fifth is situated between the pisiform and cuneiform bone. Actions.—Very little movement exists between the bones in each range, but more is permitted between the two ranges. The motions in the latter situation are those of flexion and extension. 9. The Carpo-metacarpal Articulations.—The second row of bones of the carpus articulates with the metacarpal bones of the four fingers by dorsal and palmar ligaments; and the metacarpal bone of the thumb with the trapezium by a true capsular ligament. There is also in the carpo-metacarpal articulation a thin interosseous band which passes from the ulnar edge of the os magnum to the line of junction between the third and fourth metacarpal bones. 144 CARPO-METACARPAL ARTICULATIONS. The dorsal ligaments are strong fasciculi which pass from the second range of carpal to the metacarpal bones. The palmar ligaments are thin fasciculi arranged upon the same ’ plan on the palmar surface. The synovial membrane is a continuation of the great synovial membrane of the two rows of carpal bones. The capsular ligament of the thumb is one of the three true capsular ligaments of the skeleton; the other two being the shoulder-joint and hip-joint. The articulation has a proper synovial membrane. Fig. 68.* The metacarpal bones of the four fingers are firmly connected at their bases by means of dorsal and palmar ligaments, which extend transversely from one bone to the other, and by interosseous ligaments which pass between their contiguous surfaces. Their lateral articular * A diagram shewing the disposition of the five synovial membranes of the wrist joint. 1. The sacciform membrane. 2. The second synovial membrane. 3, 3. The third, or large synovial membrane. 4. The synovial membrane between the pisiform bone and the cuneiforme. 5. The synovial membrane of the metacarpal articulation of the thumb. 6. The lower extre- mity of the radius. 7. The lower extremity of the ulna. 8. The interarti- cular fibro-cartilage. §. 'The scaphoid bone. L. The semilunare. C. The cuneiforme; the interosseous ligaments are seen passing between these three bones and separating the articulation of the wrist (2) from the articula- tion of the carpal bones (3). P. The pisiforme. T. The trapezium. T2. The trapezoides. M. The os magnum. U. The unciforme; interosseous liga- ments are seen connecting the os ay OY with the trapezoides and unci- forme. 9. The base of the metacarpal bone of the thumb. 10, 10. The bases of the other metacarpal bones. fe se ne METACARPO-PHALANGEAL ARTICULATIONS. 145 facets are lined by a reflection of the great synovial membrane of the two rows of carpal bones. Actions.—The movements of the metacarpal on the carpal bones are restricted to a slight degree of sliding motion, with the exception of the articulation of the metacarpal bone of the thumb with the trape- zium. In the latter articulation, the movements are, fleaton, extension, adduction, abduction, and circumduction. 10. Metacarpo-phalangeal Articulation.— The metacarpo-phalan- geal articulation is a ginglymoid joint: its ligaments are four in number,— Anterior, Two lateral, Transverse. The anterior ligaments are thick and fibro-cartilaginous, and form part of the articulating surface of the joints. They are grooved ex- ternally for the lodgment of the flexor tendons, and by their internal aspect form part of the articular surface for the head of the metacarpal bone. The dateral ligaments are strong narrow fasciculi, holding the bones together at each side. The ¢ransverse ligaments are strong ligamentous bands passing be- tween the anterior ligaments, and connecting together the heads of the metacarpal bones of the four fingers. The expansion of the extensor tendon over the back of the fingers takes the place of a posterior ligament. Actions.—This articulation admits of movement in four different directions, viz. of flexion, extension, adduction, and abduction, the two latter being limited toa small extent. It is also capable of cireum- duction. 1l. Articulation of the Phalanges.—These articulations are gingly- moid joints: they are formed by three ligaments. Anterior, Two lateral. The anterior ligament is firm and fibro-cartilaginous, and forms part of the articular surface for the head of the phalanges. Externally it is grooved for the reception of the flexor tendons. The lateral ligaments are very strong; they are the principal bond of connection between the bones. The extensor tendon takes the place and performs the office of a posterior ligament. Actions—The movements of the phalangeal joints are flewion and extension, these movements being more extensive between the first and second phalanges than between the second and third. In connection with the phalanges it may be proper to examine cer- tain fibrous bands termed thece or vaginal ligaments, which serve to retain the tendons of the flexor muscles in their position upon the flat L 146 HIP JOINT. surface of their bones. These fibrous bands are attached at each side to the lateral margins of the phalanges; they are thick in the inter- spaces of the joints, thin where the tendons lie upon the joints, and they are lined upon their.inner surface by synovial membrane. LIGAMENTS OF THE LOWER EXTREMITY. The ligaments of the lower extremity, like those of the upper, may be arranged in the order of the joints to which they belong; these are, the . Hip joint. . Knee joint. . Articulation between the tibia and fibula. . Ankle joint. . Articulation of the tarsal bones. . Tarso-metatarsal articulation. . Metatarso-phalangeal articulation. . Articulation of the phalanges. CONT OD Cr RP Oy DD ee 1. Hip Joint.—The articulation of the head of the femur with the acetabulum constitutes an enarthrosis, or ball and socket joint. The articular surfaces are the cup-shaped cavity of the acetabulum and the rounded head of the femur; the ligaments are five in number, viz. Capsular, Cotyloid, Tlio-femoral, Transverse. Teres, The capsular ligament (fig. 61, 8) is a strong ligamentous capsule, embracing the acetabulum superiorly, and inferiorly the neck of the femur, and connecting the two bones firmly together. It is much thicker upon the upper part of the joint, where more resistance is required, than upon the under part, and extends farther upon the neck of the femur on the anterior and superior than on the posterior and inferior side, being attached to the intertrochanteric line in front, to the base of the great trochanter above, and to the middle of the neck of the femur behind. The ilio-femoral ligament (fig. 61, 9) is an accessory and radiating band, which descends obliquely from the anterior inferior spinous pro- cess of the ilium to the anterior intertrochanteric line, and strengthens the anterior portion of the capsular ligament. The ligamentum teres (fig. 62, 7), triangular in shape is attached by a round apex to the depression just below the middle of the head of the femur, and by its base, which divides into two fasciculi, into the borders of the notch of the acetabulum. It is formed by a fasciculus of fibres, of variable size, surrounded by synovial membrane ; sometimes the synovial membrane alone exists, or the ligament is wholly absent. hg” ai Sensi — 2 i Ee ee ee On ee ee a a ee ae) KNEE JOINT. | 147 The cotylotd ligament (fig. 62, 6) is a prismoid cord of fibro-car- tilage, attached around the margin of the acetabulum, and serving to deepen that cavity and protect its edges. It is much thicker upon the upper and posterior border of the acetabulum than in front, and consists of fibres which arise from the whole circumference of the brim, and interlace with each other at acute angles. The transverse ligament is a strong fasiculus of ligamentous fibres, continuous with the cotyloid ligament, and extended across the notch in the acetabulum. It converts the notch into a foramen, through which the articular branches of the internal circumflex and obturator arteries enter the joint. The fossa at the bottom of the acetabulum is filled by a mass of fat, covered by synovial membrane, which serves as an elastic cushion to the head of the bone during its movements, This was considered by Havers as the synovial gland. The synovial membrane is extensive ; it invests the head of the femur, and is continued around the ligamentum teres into the ace- tabulum, whence it is reflected upon the inner surface of the capsular ligament back to the head of the bone. The muscles immediately surrounding and in contact with the hip- joint are, in front, the psoas and iliacus, which are separated from the capsular ligament by a large synovial bursa ; above, the short head of the rectus, and the gluteus minimus ; behind, the pyriformis, gemellus superior, obturator internus, gemellus inferior, and quadratus femoris ; and to the inner side, the obturator externus and pectineus. Actions.—The movements of the hip-joint are very extensive ; they are flexion, extension, adduction, abduction, circumduction and rotation. 2. Knee Joint.—The knee is a ginglymoid articulation of large size, and is provided with numerous ligaments; they are thirteen in number. i Anterior or ligamentum patellz, Posterior or ligamentum posticum Winslowii, - Internal lateral, Two external lateral, Anterior or external crucial, Posterior or internal crucial, Transverse, Two coronary, “sya mivoosuim, “2 Aan. igamenta alaria, Two semilunar fibro-cartilages, Synovial membrane. The first five are eaternal to the articulation; the next five are internal to the articulation ; the remaining three are mere folds of synovial membrane, and have no title to the name of ligaments. In _addition to the ligaments, there are two fibro-cartilages, which are sometimes very erroneously considered among the ligaments ; and a 148 KNEE JOINT. synovial membrane, which is still more improperly named the capsular ligament. _ The anterior ligament, or ligamentum patella, is the prolongation of the tendon of the extensor muscles of the thigh downwards to the tubercle of the tibia. It is, therefore, no ligament; and, as we have before stated, that the patella is simply a sesamoid bone, developed in the tendon of the extensor muscles for the Fig. 69.* defence of the front of the knee joint, the ligamentum patellze has no title to consider- ation, either as a ligament of the knee joint or as a ligament of the patella. A small bursa mucosa is situated be- tween the ligamentum patelle, near its insertion and the front of the tibia, and another of larger size is placed between the anterior surface of the patella and the fascia lata. The posterior ligament, ligamentum posti- cum Winslowii, is a broad expansion of ligamentous fibres which covers the whole of the posterior part of the joint. It is divisible into two lateral portions which invest the condyles of the femur, and a central portion which is depressed, and formed by the interlacement of fasciculi passing in different directions. The strong- est of these fasciculi is that which is de- rived from the tendon of the semi-membranosus and passes obliquely upwards and outwards, from the posterior part of the inner tuberosity of the tibia to the external condyle. Other accessory fasciculi are given off by the tendon of the popliteus and by the heads of the gastrocnemius. The middle portion of the ligament supports the popliteal artery and vein, and is perforated by several openings for the passage of branches of the azygos articular artery, and for the nerves of the joint. The internal lateral ligament is a broad and trapezoid layer of ligamentous fibres, attached above to the tubercle on the internal condyle of the femur, and below to the side of the inner tuberosity of the tibia. It is crossed at its lower part by the tendons of the inner hamstring from which it is separated by a synovial bursa, and it covers in the anterior slip of the semi-membranosus tendon and the inferior internal articular artery. External lateral ligaments.—The long external lateral ligament is a * An anterior view of the ligaments of the knee joint. 1. The tendon of the quadriceps extensor muscle of the leg. 2. The patella. 3. The anterior ligament, or ligamentum packs, near its insertion. 4,4. The synovial membrane. 5. The internal lateral ligament. 6. The long external lateral ligament. 7. The anterior superior tibio-fibular ligament. cote JOINT. 149 strong rounded cord, which descends from the posterior part of the tubercle upon the external condyle of the femur to the outer part of the head of the fibula. The short external lateral ligament is an irregular fasciculus situated behind the preceding, arising from the external condyle near the origin of the head of the gastrocnemius muscle, and inserted into the posterior part of the head of the fibula. It is firmly connected with the external semilunar fibro-cartilage, and appears principally intended to con- nect that cartilage with the fibula. The long external lateral ligament is covered in by the tendon of the biceps, and has passing beneath it the tendon of origin of the popliteus muscle, and the inferior external articular artery. The true ligaments within the joint are the crucial, transverse, and coro- nary. The anterior, or eaternal crucial liga- ment, arises from the depression upon the head of the tibia in front of the spinous process, and passes upwards and backwards to be inserted into the inner surface of the outer condyle of the femur, as far as its posterior border. It is smaller than the posterior. The posterior, or internal crucial ligament, arises from the depres- sion upon the head of the tibia, behind the spinous process, and passes upwards and forwards to be inserted into the inner condyle of the femur. This ligament is less oblique and larger than the anterior. | The transverse ligament is a small slip of fibres which extends transversely from the external semilunar fibro-cartilage, near its an- terior extremity, to the anterior convexity of the internal cartilage. The coronary ligaments are the short fibres by which the convex borders of the semilunar cartilages are connected to the head of the tibia, and to the ligaments surrounding the joint. The semilunar fibro-cartilages are two falciform plates of fibro- cartilage, situated around the margin of the head of the tibia, and serving to deepen the surface of articulation for the condyles of the femur. They are thick along their convex border, and thin and sharp along the concave edge. Fig. 70.* * A posterior view of the ligaments of the knee-joint. 1. The fasciculus of the ligamentum posticum Winslowii, which is derived from, 2. the tendon of the semi-membranosus muscle; the latter is cut short. 3. The process of the tendon which spreads out in the fascia of the popliteus muscle. 4, The process which is sent inwards beneath the internal lateral ligament. 5. The osterior part of the internal lateral ligament. 6. The long external lateral palace 7. The short external lateral ligament. 8. The tendon of the popliteus muscle cut short. 9. The posterior superior tibio-fibular ligament. 150 KNEE JOINT. The internal semilunar fibro-cartilage forms an oval cup for the reception of the internal condyle ; it is connected by its convex border _to the head of the tibia, and to the internal and posterior ligaments, by means of its coronary ligament; and by its two extremities is firmly implanted into the depressions in front and behind the spinous process, The eaternal semilunar fibro-cartilage bounds a circular fossa for the external condyle: it is connected by its convex border with the head of the tibia, and to the external and posterior ligaments, by means of its coronary ligament ; by its two extremities it is in- serted into the depression between the two projections which con- stitute the spinous process of the tibia. Fig. 71.* The two extremities of the external - cartilage being inserted into the same fossa form almost a complete circle, and the cartilage being somewhat broader than the internal, nearly covers the articular surface of the tibia. The external semilunar fibro- cartilage besides giving off a fasci- culus from its anterior border to con- stitute the transverse ligament, is continuous by some of its fibres with the extremity of the anterior crucial ligament ; posteriorly it divides into three slips ; one, a strong cord, as- cends obliquely forwards and is in- serted into the anterior part of the inner condyle in front of the poste- rior crucial ligament ; another is the fasciculus of insertion into the fossa of the spinous process ; and the third, of small size, is continuous with the posterior part of the anterior crucial ligament. The ligamentum mucosum is a slender conical process of synovial membrane enclosing a few ligamentous fibres which proceed from the transverse ligament. It is connected, by its apex, with the anterior part of the condyloid notch, and by its base is lost in the mass of fat which projects into the joint beneath the patella. * The right knee joint laid open from the front, in order to shew the in- ternal ligaments. 1. The cartilaginous surface of the lower extremity of the femur with its two condyles; the figure 5 rests upon the external; the figure 3 upon the internal condyle. 2. The anterior crucial ligament. 3. The pos- terior crucial ligament. 4. The transverse ligament. 5. The attachment of the ligamentum mucosum ; the rest has been removed. 6. The internal semi- lunar fibro-cartilage. 7. The external fibro-cartilage. 8. A part of the liga- mentum patellee turned down. 9. The bursa, situated between the ligamen- tum patellee and the head of the tibia; it has been laid open. 10. The anterior superior tibio-fibular ligament. 11. The upper part of the interosseous mem- brane ; the opening above this membrane is for the passage of the anterior tibial artery. snes KNEE JOINT. 151 The alar ligaments are two fringed folds of synovial membrane, extending from the ligamentum mucosum, along the edges of the Fig. 72.* mass of fat to the sides of the : patella. : The synovial membrane of the knee joint is by far the most exten- sive in the skeleton. It invests the cartilaginous surfaces of the con- dyles of the femur, of the head of tibia, and of the inner surface of the patella; it covers both surfaces of the semilunar fibro-cartilages, and is reflected upon the crucial liga- ments, and upon the inner surface of the ligaments which form the cir- cumference of the joint. On each side of the patella, it lines the ten- dinous aponeuroses of the vastus in- ternus and vastus externus muscles, and forms a pouch of considerable size between the extensor tendon -and the front of the femur. It also forms the folds in the interior of the joint, called .“ ligamentum mucosum,” and “ ligamenta alaria.” The superior pouch of the synovial membrane is supported and raised during the movements of the limb by a small muscle, the subcrureus, which is inserted into it. Between the ligamentum patella and the synovial membrane is a considerable mass of fat, which presses the membrane towards the interior of the joint, and occupies the fossa between the two con- dyles. * A longitudinal section of the left knee joint, shewing the reflections of its synovial membrane. 1. The cancellous structure of the lower part of the femur. 2. The tendon of the extensor muscles of the leg. 3. The patella. 4. The ligamentum patelle. 5. The cancellous structure of the head of the tibia. 6. A bursa situated between the ligamentum patellee and the head of the tibia. 7. The mass of fat projecting into the cavity of the joint below the patella. * * The synovial membrane. 8. The pouch of synovial membrane which ascends between the tendon of the extensor muscles of the leg, and the front of the lower extremity of the femur. 9. One of the alar ligaments ; the other has been removed with the opposite section. 10. The ligamentum mucosum left entire; the section being made to its inner side. 11. The anterior or external crucial ligament. 12. The posterior ligament. The scheme of the synovial membrane, which is here presented to the student, is divested of all unnecessary complications. It may be traced from the sacculus (at 8), along the inner surface of the patella; then over the adipose mass (7) from which it throws off the mucous ligament (10); then over the head of the tibia, forming a sheath to the crucial ligaments; then upwards along the posterior ligament and condyles of the femur, to the sacculus whence its examination commenced. 152 TIBIO-FIBULAR ARTICULATIONS. Besides the proper ligaments of the articulation, the joint is pro- tected on its anterior part by the fascia lata, which is thicker upon the outer than upon the inner side, by a tendinous expansion from the vastus internus, and by some scattered ligamentous fibres which are inserted into the sides of the patella. Actions.—The knee-joint is one of the strongest of the articulations of the body, while at the same time it admits of the most perfect de- gree of movement in the directions of fleaion and eatension. During flexion the articular surface of the tibia glides forward on the condyles of the femur, the lateral ligaments, the posterior, and the crucial liga- ments are relaxed, while the ligamentum patellz being put upon the stretch, serves to press the adipose mass into the vacuity formed in the front of the joint. In eatension all the ligaments are put upon the stretch with the exception of the ligamentum patella. When the knee is semi-flexed, a partial degree of rotation is permitted. 3. Articulation between the Tibia and Fibula.— The tibia and fibula are held firmly connected by means of seven ligaments, viz. Anterior, Posterior, . above. Interosseous membrane, Interosseous inferior, Anterior, ete Posterior, ' Transverse. The anterior superior ligament is a strong fasciculus of parallel fibres passing obliquely downwards and outwards from the inner tuberosity of the tibia, to the anterior surface of the head of the fibula. The posterior superior ligament is disposed in a similar manner upon the posterior surface of the joint. Within the articulation there is a distinct synovial membrane which is sometimes continuous with that of the knee-joint. The interosseous membrane or superior interosseous ligament is a broad layer of aponeurotic fibres which pass obliquely downwards and outwards, from the sharp ridge on the tibia, to the inner edge of the fibula and are crossed at an acute angle by a few fibres passing in the opposite direction. The ligament is deficient above, leaving a con- siderable interval between the bones, through which the anterior tibial artery takes its course forwards to the anterior aspect of the leg, and near its lower third there is an opening for the anterior peroneal artery and vein. The interosseous membrane is in relation, in front, with the tibialis anticus, extensor longus digitorum, and extensor proprius pollicis muscle, with the anterior tibial vessels and nerve, and with the ante- rior peroneal artery ; and behind with the tibialis posticus, and flexor longus digitorum muscle, and with the posterior peroneal artery. ANKLE JOINT. 153 The inferior interosseous ligament consists of short and strong fibres, which hold the bones firmly together inferiorly, where they are nearly in contact. This articulation is so firm that the fibula is likely to be broken in the attempt to rupture the ligament. The anterior inferior ligament is a broad band, consisting of two fasciculi of parallel fibres which pass obliquely across the anterior aspect of the articulation of the two bones at their inferior extremity, - from the tibia to the fibula. The posterior inferior ligament (fig. 75, 2) is a similar band upon the posterior surface of the articulation. Both ligaments project some- what below the margin of the bones, and serve to deepen the cavity of articulation for the astragalus. The transverse ligament (fig. 75, 3) is a narrow band of ligamen- tous fibres, continuous with the preceding, and passing transversely across the back of the ankle joint between the two malleoli. The synovial membrane of the inferior tibio-fibular articulation, is a duplicature of the synovial membrane of the ankle joint reflected up- wards for a short distance between the two bones. ' Actions.—An obscure degree of movement exists between the tibia -- and fibula, which is principally calculated to enable the latter to resist injury by yielding for a trifling extent to the pressure exerted. 4. Ankle-joint.—The ankle is a ginglymoid articulation ; the surfaces entering into its formation are the under surface of the tibia with its malleolus and the malleolus of the fibula, above, and the surface of the astragalus with its two lateral facets, below. The ligaments are three in number : Anterior, Fig. 73.* Internal lateral, External lateral. The anterior ligament is a thin membranous layer, passing from the margin of the tibia, to the astragalus in front of the articular surface. It is in relation, in front, with the ex- tensor tendons of the great and les- ser toes, with the tendons of the tibialis anticus and peroneus tertius, and with the anterior tibial vessels and nerve. Postertorly it lies in contact with the extra-synovial adi- pose tissue and with the synovial membrane. * An internal view of the ankle joint. 1. The internal malleolus of the tibia. 2,2. Part of the astragalus; the rest is concealed by the ligaments. 3. The os calcis. 4. The scaphoid bone. 5. The internal cuneiform bone. 6. The internal lateral or deltoid ligament. 7. The anterior ligament. 8. The tendo Achillis; a small bursa is seen interposed between this tendon and the tuberosity of the os calcis. 154 TARSAL ARTICULATIONS. The internal lateral or deltoid ligament is a triangular layer of fibres, attached superiorly by its apex to the internal malleolus, and inferiorly _ by an expanded base to the astragalus, os calcis, and scaphoid bone. Beneath the superficial layer of this ligament is a much stronger and thicker fasciculus which connects the apex of the internal malleolus with the side of the astragalus. This internal lateral ligament is covered in and partly concealed by the tendon of the tibialis posticus, and at its posterior part is in rela- tion with the tendon of the flexor longus digitorum, and with that of the flexor longus pollicis. ; The eaternal lateral ligament consists of three strong fasciculi, which proceed from the inner side of the external malleolus, and diverge in three different directions. The anterior fasciculus passes forwards, and is attached to the astragalus; the posterior, backwards, and is connected with the astragalus posteriorly; and the middle, longer than the other two, descends to be inserted into the outer side of the os calcis, “Tt is the strong union of this bone,” says Sir Astley Cooper, with the tarsal bones by means of the external lateral ligaments, “which leads to its being more frequently fractured than dis- located.” The transverse ligament of the Fig. 74.* tibia and fibula occupies the place of a posterior ligament. It is ix relation, behind, with the posterior tibial vessels and nerve, and with the tendon of the tibialis posticus muscle ; and tm front, with the ex- tra-synovial adipose tissue, and synovial membrane. The Synovial membrane invests the cartilaginous surfaces of the tibia and fibula (sending a duplicature upwards between their lower ends), and the upper surface and two sides of the astragalus. It is then re- flected upon the anterior and lateral ligaments, and upon. the transverse ligament posteriorly. Actions.—The movements of the ankle joint are flewion and eatension only, without lateral motion. 5. Articulation of the Tarsal Bones.—The ligaments which connect the seven bones of the tarsus to each other are of three kinds,— * An external view of the ankle joint. 1. The tibia. 2. The external malleolus of the fibula. 3,3. The astragalus. 4. The os calcis. 5. The cu- boid bone. 6. The anterior fasciculus of the external lateral ligament attached to the astragalus. 7. Its middle fasciculus, attached to the os calcis. 8 Its aac? fasciculus, attached to the astragalus. 9. The anterior ligament of ankle. ee se TARSAL ARTICULATIONS. 155 Dorsal, Plantar, Interosseous. The dorsal ligaments are small fasciculi of parallel fibres, which pass — from each bone to all the neighbouring bones with which it articulates. The only dorsal ligaments deserving of particular mention are, the ea- ternal and posterior astragaloid, which, with the interosseous ligament, complete the articulation of the astragalus with the os calcis ; the superior and internal calcaneo-cuboid ligaments ; and the superior astragalo-scaphoid ligament. The internal cal boid and the superior calcaneo-scaphoid ligament, which are closely united poste- riorly in the deep groove which intervenes between the astragalus and os calcis, separate anteriorly to reach their respective bones; they form the principal bond of connection between the first and second range of the bones of the foot. It is the division of this portion of these liga- ments that demands the especial attention of the surgeon in performing Chopart’s operation. The plantar ligaments have the same disposition on the plantar - surface of the foot; three of them, however, are of a large size and have especial names, viz. the Calcaneo-scaphoid, Long calcaneo-cuboid, Short calcaneo-cuboid. The inferior caleaneo-scaphoid ligament is a broad and fibro-cartilaginous band of ligament, which passes forwards from the anterior, and inner border of the os calcis to the edge of the scaphoid bone. In addition to connecting the os calcis and scaphoid, it supports the astra- galus, and forms part of the cavity in which the rounded head of the latter bone is received. It is lined upon its upper surface by the synovial membrane of the astragalo-scaphoid articulation. The firm connection of the os calcis with the scaphoid bone, and the feebleness of the astra- galo-scaphoid articulation are conditions favor- able to the occasional dislocation of the head of the astragalus. The long calcaneo-cuboid, or ligamentum longum plantz, is a long band of ligamentous fibres, which proceeds from the under surface of the os calcis to the rough surface on the under part of the cuboid bone, * A posterior view of the ankle joint. 1. The lower part of the inter- osseous membrane. 2. The posterior inferior ligament connecting the tibia and fibula. 3. The transverse ligament. 4. The internal lateral ligament. 5. The posterior fasciculus of the external lateral ligament. 6. The middle fasciculus of the external lateral ligament. 7. The synovial membrane of the ankle joint. 8. The os calcis. 156 TARSO-METATARSAL ARTICULATIONS, its fibres being continued onwards to the bases of the third and fourth metatarsal bones. _ This ligament forms the inferior boundary of a canal in the cuboid bone, through which the tendon of the peroneus longus passes to its insertion into the base of the metatarsal bone of the great toe. The short calcaneo-cuboid, or ligamentum breve planta, is situ- ated nearer to the bones than the long plantar ligament, from which it is separated by adipose tissue; it is broad and extensive, and ties the under surfaces of the os calcis and cuboid bone firmly together. The interosseous ligaments are five in number; they are short and strong ligamentous fibres situated between adjoining bones, and firmly attached to their rough surfaces. One of these, the calcaneo-astraga- loid, is lodged in the groove between the upper surface of the os calcis, and the lower of the astragalus. It is large and very strong, consists of vertical and oblique fibres, and serves to unite the os calcis and astra- galus solidly together. The second interosseous ligament, also very strong, is situated between the sides of the scaphoid and cuboid bone ; while the three remaining interosseous ligaments connect strongly together the three cuneiform bones and the cuboid. The synovial membranes of the tarsus are four in number: one, for the posterior calcaneo-astragaloid articulation; @ second, for the anterior calcaneo-astragaloid and astragalo-scaphoid articulation. Occa- sionally an additional small synovial membrane is found in the an- terior calcaneo-astragaloid joint ; a third, for the calcaneo-cuboid arti- culation; and a fourth, the large tarsal synovial membrane for the articulations between the scaphoid and three cuneiform bones, the cuneiform bones with each other, the external cuneiform bone with the cuboid, and the two external cuneiform bones with the bases of the second and third metatarsal bones. The prolongation which reaches the metatarsal bones passes forwards between the internal and middle cuneiform bones. A small synovial membrane is sometimes 0% with between the contiguous surfaces of the scaphoid and cuboid one. Actions.—The movements permitted by the articulation between the astragalus and os calcis, are a slight degree of gliding, in the direc- tions forwards and backwards and laterally from side to side. The movements of the second range of tarsal bones is very trifling, being greater between the scaphoid and three cuneiform bones than in the other articulations. The movements occurring between the first and second range are the most considerable ; they are adduction and abdue- tion, and, in a minor degree, flewion, which increases the arch of the foot, and eatension which flattens the arch. _ 6. Tarso-metatarsal Articulation.—The ligaments of this articula- tion are, Dorsal, Plantar, Interosseous. 0 pee = METATARSO-PHALANGEAL ARTICULATIONS, 157 The dorsal ligaments connect the metatarsal to the tarsal bones, and the metatarsal bones with each other. The precise arrangement of these ligaments is of little importance, but it may be remarked, that the base of the second metatarsal bone, articulating with the three cuneiform bones receives a ligamentous slip from each, while the rest articulating with a single tarsal bone receive only a single tarsal slip. The plantar ligaments have the same disposition on the plantar surface. The interosseous ligaments are situated Fig. 76.* between the bases of the metatarsal bones of the four lesser toes; and also between the bases of the second and third metatarsal bones, and the internal and external cunei- form bones. The metatarsal bone of the second toe is implanted by its base between the internal and external cuneiform bones, and is the most strongly articulated of all the meta- tarsal bones. This disposition must be recollected in amputation at the tarso-meta- tarsal articulation. The synovial membranes of this articula- tion are three in number: one for the meta- tarsal bone of the great toe; one for the second and third metatarsal bones, which is continuous with the great tarsal synovial membrane ; and one for the fourth and fifth metatarsal bones. Actions.—The movements of the meta- tarsal bones upon the tarsal, and upon each other are very slight; they are such only as contribute to the strength of the foot by permitting of a certain degree of yield- ing to opposing forces. 7 Motoat rey ; SO-T geal Articulation.— The ligaments of this articulation, like those of the articulation be- tween the first phalanges and metacarpal bones of the hand, are, * The ligaments of the sole of the foot. 1. The oscalcis. 2. The astra- . 3. The tuberosity of the scaphoid bone. 4. The long calcaneo-cuboid igament. 5. Part of the short calcaneo-cuboid ligament. 6. The calcaneo- scaphoid ligament. 7. The plantar tarsal ligaments. 8, 8. The tendon of the peroneus longus muscle. 9, 9. Plantar tarso-metatarsal ligaments. 10. Plan- tar ligament of the metatarso-phalangeal articulation of the great toe; the same ligament is seen upon the other toes. 11. Lateral ligaments of the metatarso-phalangeal articulation. 12. Transverse ligament. 13. The lateral gpa of the phalanges of the great toe ; the same ligaments are seen upon e other toes. 158 ARTICULATION OF THE PHALANGES. Anterior or plantar, Two lateral, Transverse. ‘The anterior or plantar ligaments are thick and fibro-cartilaginous, and form part of the articulating surface of the joint. The lateral ligaments are short and very strong, and situated on each side of the joints. The transverse ligaments are strong bands, which pass transversely between the anterior ligaments. The expansion of the extensor tendon supplies the place of a dorsal ligament. Actions. —The movements of the first phalanges upon the rounded heads of the metatarsal bones, are flexion, eatension, adduction and abduction. 8. Articulation of the Phalanges.—The ligaments of the phalanges are the same as those of the fingers, and have the same disposition ; their actions are also similar. They are, Anterior or plantar, , Two lateral. ae ee ee 0 Sele eich a lS nite as te. ea Re ee ee ee eee ee 159 CHAPTER IIL ON THE MUSCLES. Musc zs are the moving organs of the animal frame ; they consti- tute by their size and number the great bulk of the body, upon which they bestow form and symmetry. In the limbs they are situated around the bones, which they invest and defend, while they form to some of the joints a principal protection. In the trunk they are spread out to enclose cavities, and constitute a defensive wall capable of yielding to internal pressure, and again returning to its original position. Their colour presents the deep red which is characteristic of flesh, and their form is variously modified, to execute the varied range of movements which they are required to effect. Muscle is composed of a number of parallel fibres placed side by side, and supported and held together by a delicate web of areolar tissue ; so, that if it were possible to remove the muscular substance, we should have remaining a beautiful reticular frame-work, possessing the exact form and size of the muscle without its colour and solidity. Towards the extremity of the organ the muscular fibre ceases, and the areolar structure becomes aggregated and modified, so as to constitute those glistening fibres and cords by which the muscle is tied to the surface of bone, and which are called tendons. Almost every muscle in the body is connected with bone, either by tendinous fibres, or by an aggregation of those fibres constituting a tendon ; and the union is so firm, that, under extreme violence, the bone itself rather breaks than permits of the separation of the tendon from its attachment. In the broad muscles the tendon is spread so as to form an expansion, caer aponeurosis (aaa, longé ; vedgov,* nervus—a nerve widely spread out). Muscles present various modifications in the arrangement of their fibres in relation to their tendinous structure. Sometimes they are completely longitudinal, and terminate at each extremity in tendon, the entire muscle being fusiform in its shape; in other situations they are disposed like the rays of a fan, converging to a tendinous point, as the temporal, pectoral, glutei, &c., and constitute a radiate muscle, Again, they are penniform, converging like the plumes of a pen to one side of a tendon, which runs the whole length of the muscle as in the peronei ; or bipenniform, converging to both sides of * The ancients named all the white fibres of the body vevga; the term has since been limited to the nerves. 160 STRUCTURE OF MUSCLE. the tendon. In other muscles the fibres pass obliquely from the surface of a tendinous expansion spread out on one side, to that of an- . other extended on the opposite side, as in the semi-membranosus ; or, they are composed of penniform or bipenniform fasciculi as in the del- toid, and constitute a compound muscle. The nomenclature of the muscles is defective and confused, and is generally derived from some prominent character which each muscle presents ; thus, some are named from their situation, as the tibialis, peroneus ; others from their uses, as the flexors, extensors, adductors, abductors, levators, tensors, &c. Some again from their form, as the trapezius, triangularis, deltoid, &c. ; and others from their direction, as the rectus, obliquus, transversalis, &c. Certain muscles have re- ceived names expressive of their attachments, as the sterno-mastoid, sterno-hyoid, &c. ; and others, of their divisions, as the biceps, triceps, digastricus, complexus, &c. In the description of a muscle we express its attachment by the words “origin” and “insertion ;” the term origin is generally applied to the more fixed or central attachment, or to the point towards which the motion is directed, while insertion is assigned to the more movable point, or to that most distant from the centre; but there are many exceptions to this principle, and as many muscles pull equally by both extremities, the use of such terms must be regarded as purely arbitrary. In structure, muscle is composed of bundles of fibres of variable size called fasciculi, which are enclosed in a cellular membranous invest- ment or sheath, and the latter is continuous with the cellular frame- work of the fibres. Each fasciculus is composed of a number of smaller bundles, and these of singles fibres, which, from their minute size and independent appearance, have been distinguished by the name of ulti- mate fibres. The ultimate fibre is found by microscopic investigation to be itself a fasciculus (ultimate fasciculus), made up of a number of ultimate fibrils enclosed in a delicate sheath or myolemma.* Two kinds of ultimate muscular fibre exist in the animal economy ; viz., that of voluntary or animal life, and that of involuntary or organic life. The ultimate fibre of animal life is known by its size, by its uni- formity of calibre, and especially by the very beautiful transverse markings which occur at short and regular distances throughout its whole extent. It also presents other markings or strie#, having a longitudinal direction, which indicate the existence of fibrille within * In the summer of 1836, while engaged with Dr. Jones Quain in the exami- nation of the animal tissues with a simple dissecting microscope, constructed by Powell, I first saw that the ultimate fibre of muscle was invested by a proper sheath, for which I proposed the term ‘‘ Myolemma;’’ a term which was adopted by Dr. Quain in the fourth edition of his ‘‘ Elements of Anatomy.’’ We at that time believed that the transverse folding of that sheath gave rise to the appearance of transverse strize, an opinion which subsequent examinations proved to be incorrect. Mr. Bowman employs the term ‘‘ Sarcolemma,’’ as synonymous with Myolemma. ee ee - Pe ee ee a en! i eu ‘ igi! ite =e. Re ers ee yielat » =k eS eee ee ee STRUCTURE OF MUSCLE. 161 its myolemma. The myolemma, or investing sheath of the ultimate fibre is thin, structureless and transparent. According to Mr. Bowman ™* the ° ultimate fibresare polygonal in shape, Fig. 77.+ [fig.77 ] from mutual pressure. They are also variable in their size, not merely in different classes and genera of animals and different sexes, but even in the same muscle. For ex- ample, the average diameter of the ultimate fibre in the human female is z3,, while that of the male is sis, the average of both being aug: The largest fibres are met with in fishes, in which animals they average 34,5; the next largest are found in man, while in other classes they range in the following order :—insects z+, ; reptiles aa 3 Mammalia 53, ; birds <4. The ultimate fibrils of animal life, according to Mr. Bowman, are beaded filaments consisting of a regular succession of segments and constrictions, the latter being narrower than the former, and the com- ponent substance probably less dense. An ultimate fibre consists of a bundle of these fibrils, which are so disposed that all the segments and all the constrictions correspond, and in this manner give rise to the alternate light and dark lines of the transverse striz. The fibrils are connected together with very dif- ferent degrees of closeness in different animals ; in man they are but slightly adherent, and distinct lon- gitudinal lines of junction may be Fig. 78.¢ observed between them ; they also Y) f A separate very easily when mace- rated for some time. Besides the more usual separation of the ulti- mate fibre into fibrils, it breaks when stretched, into transverse sections [fig. 78,] corresponding * On the Minute structure and Movements of Voluntary Muscle. By Wm. Bowman, Esq. From the Philosophical Transactions for 1840. + Transverse section of ultimate fibres of the biceps, copied from the illus- trations to Mr. Bowman’s paper. In this figure the polygonal form of the fibres is seen, and their composition of ultimate fibrils. ¢ An ultimate fibre, in which the transverse splitting into dises, in the direc- with the dark line of the striae, and consequently with the constric- tion of the constrictions of the ultimate fibrils is seen. From Mr. Bowman’s paper. tions of the fibrille. When this division occurs with the greatest M 162 STRUCTURE OF MUSCLE. facility, the longitudinal lines are indistinct, or scarcely perceptible. “ In fact,” says Mr. Bowman, “the primitive fasciculus seems to con- sist of primitive component segments or particles, arranged so as to form, in one sense, fibrillee, and in another sense, discs ; and which of these two may happen to present itself to the observer, will depend on the amount of adhesion, endways or sideways, existing between the segments. Generally, in a recent fasciculus, there are transverse strie, shewing divisions into discs, and longitudinal striae, marking its composition by fibrillz.” Mr. Bowman has observed that in the substance of the ultimate fibre there exist minute “oval or circular discs, frequently concave on one or both surfaces, and containing, somewhere near the centre, one, two, or three minute dots or granules.” Occasionally they are seen to present irregularities of form, which Mr. Bowman is inclined to regard as accidental. They are situated between, and are connected with the fibrils, and are distributed in pretty equal numbers through the fibre. These corpuscles are the nuclei of the nucleated cells from which the muscular fibre was originally developed. From observing, ; however, that their “absolute number Fig. 79." is far greater in the adult than in the sf foetus, while their number, relatively to the bulk of the fasciculi, at these two epochs, remains nearly the same,” Mr. Bowman regards it as certain, that “ during development, and subsequent- ly, a further and successive deposit of corpuscles” takes place. The corpus- cles are brought into view only when the muscular fibre is acted upon by a solution of “one of the milder acids, as the citric.” ; According to my own investiga- tions,+ the ultimate fibril of animal life is cylindrical when isolated, and probably polygonal from pressure when forming part of an ulti- mate fibre or fasciculus. It measures in diameter s545q of an inch, and is composed of a succession of cells connected by their flat sur- faces. The cells are filled with a transparent substance, which I have termed myoline. The myoline differs in density in different cells, and from this circumstance bestows a peculiarity of character on certain of the cells; for example, when a fibril in its passive state is examined, there will be seen a series of dark oblong bodies separated by light spaces of equal length ; now the dark bodies are _* Mass of ultimate fibres from the pectoralis major of the human feetus, at nine months. These fibres have been immersed in a solution of tartaric acid, and their ‘‘ numerous corpuscles, turned in various directions, some presenting nucleoli,’’ are shewn. _From Mr. Bowman’s paper. + These were made on dissections of fresh human muscle, prepared with great care by Mr. Lealand, partner of the eminent optician, Mr. Powell. STRUCTURE OF MUSCLE, 163 ~ 100) So) et ee i) oe i) ee | each composed of a pair of cells Fig. 80 * containing the densest form of myo- = 2 line, and are hence highly refrac- P ‘gt tive while the transparent spaces p Eh eB are constituted by a pair of cells con- 2 16 4 2 taining a more fluid myoline. When the fibrils are collected together so as to form an ultimate fibre or fasciculus, the appearance of the cell is altered ; those which look dark in the single fibril, that is, the most refractive, being ranged side by side, constitute the bright band; while the transparent cells of the single fibril are the shaded stria of the fibre. When the ultimate fibril is very much stretched, the two highly re- fractive cells appear each to be double ; while the transparent space is evidently composed of four cells. The ultimate fibre of organic life [fig. 81, D, &] is a simple homo- geneous filament, much smaller than the fibre of animal life, flat, and without transverse markings. Besides these characters there may generally be seen a dark line or several dark points in its interior, and not unfrequently the entire fibre appears enlarged at irregular dis- tances. These appearances are due to the presence of the unobli- terated nuclei of cells from which the fibre was originally developed. The fibres of organic life are collected into fasciculi of various size and are held together by dark nuclear fibres similar to those which bind the fasciculi of fibrous tissue (p. 114). The development of muscular fibre is effected by means of the formation of nucleated cells out of an original blastema, and the con- version of those cells, by a process already described (p. 5) into the tubuli of ultimate fibres, while their contents, by a subsequent de- velopmental action are transformed into ultimate fibrils. According S| | A | | a | D | | | | | > Se es se * Structure of the ultimate muscular fibril and fibre of animal life. A. An ultimate muscular fibril in the state of partial contraction. s. A similar fibril in the state of ordinary relaxation. This fibril measured soaun of an inch in diameter. ; c. A similar fibril put upon the stretch, and measuring saaua of an inch in diameter. p. Plan of a portion of an ultimate fibre, shewing the manner in which the transverse strize are produced by the collocation of the fibrils. ; Nos. 1, 1. The pair of highly-refractive cells; they form the dark parts of the single fibrils, but the bright parts of the fibre p. In the stretched fibril c, each cell has the appearance of being double. 2,2. The pair of less refractive cells, light in the single fibrils, but forming the shaded stria inp. The transverse septum between these cells is very conspicuous; and in c two other septa are seen to exist, making the number of transparent cells four. In p, the tier of ang So gana above the dark tier is partially illumined from the obliquity of the hght. 164 STRUCTURE OF MUSCLE. Fig. $1.* to this view the cell membranes constitute the myolemma, and the contents of the cell are a blastema out of which new cells are formed. The disposition of these latter cells, in the production of fibrillee, is probably much more simple than has hitherto been conceived. In the muscular fibre of organic life the process would seem to stop short of the formation of fibrille, the cells being accumulated with- out apparent order. The corpuscles, observed by Mr. Bowman, in foetal muscle [fig. 79] and the nodosities of organic fibre are obviously undeveloped cells and nuclei. Muscles are divided into two great classes, voluntary and involun- tary, to which may be added as an intermediate and connecting link, the muscle of the vascular system, the heart. The voluntary, or system of animal life, is developed from the ex- ternal or serous layer of the germinal membrane, and comprehends the whole of the muscles of the limbs and of the trunk. The involuntary or organic system is developed from the internal or mucous layer, and constitutes the thin muscular structure of the intestinal canal, bladder, and internal organs of generation. At the commencement of the ali- mentary canal in the cesophagus, and near its termination in the rectum, the muscular coat is formed by a blending of the fibres of both classes. The heart is developed from the middle, or vascular layer of the germinal membrane ; and although involuntary in its action, is * a. A muscular fibre of animal life enclosed in its myolemma; the trans- verse and longitudinal strize are seen. B. An ultimate fibril of muscular fibre of animal life, according to Mr. Bow- man. c. A muscular fibre of animal life, similar to a, but more highly magnified. Its myolemma is so thin and transparent as to permit the ultimate fibrils to be seen through. The true nature of the longitudinal strize is seen in this fibre, as well as the mode of formation of the transverse striz. _ D. A muscular fibre of organic life from the urinary bladder, magnified 600 times, linear measure. Two of the nuclei are seen. E. A muscular fibre of 0 ic life, from the stomach, magnified 600 times. The diameter of this and of the preceding fibre, midway between the nuclei, was aos of an inch. ee fms ee ee ee te * MUSCLES OF THE HEAD AND NECK. 165 composed of ultimate fibres having the transverse strize of the muscle of animal life. The muscles may be arranged in conformity with the general divi- sion of the body into,—1. Those of the head and neck. 2. Those of the trunk. 3. Those of the upper extremity. 4. Those of the lower extremity, MUSCLES OF THE HEAD AND NECK. The muscles of the head and neck admit of a subdivision into those of the head and face, and those of the neck. Muscles of the Head and Face-—These muscles may be divided into groups corresponding with the natural regions of the head and face ; the groups are eight in number, viz.— 1. Cranial group. 2. Orbital group. 3. Ocular group. 4, Nasal group. 5. Superior labial group. 6. Inferior labial group. 7. Maxillary group. 8. Auricular group. The muscles of each of these groups may be thus arranged— 1. Cranial group. Occipito-frontalis. 2. Orbital group. Orbicularis palpebrarum, Corrugator supercilii, Tensor tarsi. 3. Ocular group. Levator palpebree, Rectus superior, Rectus inferior, Rectus internus, Rectus externus, Obliquus superior, Obliquus inferior. 4. Nasal group. Pyramidalis nasi, Compressor nasi, Dilatator naris. 5. Superior labial group, ( Orbicularis oris), Levator labii superioris alzeque nasi, Levator labii superioris proprius, Levator anguli oris, Zygomaticus major, Zygomaticus minor, Depressor labii superioris aleeque nasi. 6. Inferior labial group. (Orbicularis oris),* Depressor labii inferioris, Depressor anguli oris, Levator labii inferioris. 7. Maxillary group. Masseter, Temporalis, Buccinator, Pterygoideus externus, Pterygoideus internus. 8. Auricular group. Attollens aurem, Attrahens aurem, Retrahens aurem. * The orbicularis oris, from encircling the mouth, belongs necessarily to both the superior and inferior labial regions; it is therefore enclosed within parentheses in both. 166 CRANIAL GROUP. 1. Cranial group.—Occipito-frontalis. Dissection.—The occipito-frontalis is to be dissected by making a longitudinal incision along the vertex of the head, from the tubercle on the occipital bone to the root of the nose ; and a second incision along the forehead and around the side of the head, to join the two extremities of the preceding. Dissect the integument and superficial fascia carefully outwards, beginning at the anterior angle of the flap, where the muscular fibres are thickest, and remove it altogether. * The muscles of the head and face. 1. The frontal portion of the occipito- frontalis. 2. Its occipital portion. 3. Its aponeurosis. 4. The orbicularis alpebrarum, which conceals the corrugator supercilii and tensor tarsi. 5- e pyramidalis nasi. 6. The compressor nasi. 7. The orbicularis oris. 8. The levator labii superioris aleeque nasi; the adjoining fasciculus between numbers 8 and Q is the labial portion of the muscle. 9. The levator labii supe- rioris proprius; the lower part of the levator anguli oris is seen between the muscles 10 and 11. 10, The zygomaticus minor. 11. The zygomaticus major. 12. The depressor labii inferioris. 13. The depressor anguli oris. 14. The levator labii inferioris. 15. The superficial portion of the masseter. 16. Its deep portion. 17. The attrahens aurem. 18. The buccinator. 19. The attol- lens aurem. 20. The temporal fascia which covers in the temporal muscle. 21. The retrahens aurem. 22. The anterior belly of the digastricus muscle ; the tendon is seen passing through its poeeuee pulley. 23. The stylo-hyoid muscle pierced by the posterior belly of the digastricus. 24. The mylo-hyoi- deus muscle. 25. The upper part of the sterno-mastoid. 26. The upper part of the trapezius. The muscle between 25 and 26 is the splenius. —_ ee ORBITAL GROUP. 167 This dissection requires care ; for the muscle is very thin, and without attention would be raised with the integument. There is no deep _ fascia on the face and head, nor is it required ; for here the muscles are closely applied against the bones upon which they depend for support, whilst in the extremities the support is derived from the dense layer of fascia by which they are invested, and which forms for each a dis- tinct sheath. The OcctPrro-FRONTALIS is a broad musculo-aponeurotic layer, which covers the whole of the side of the vertex of the skull, from the occiput to the eyebrow. It arises by tendinous fibres from the outer two-thirds of the superior curved line of the occipital, and from the mastoid portion of the temporal bone. Its insertion takes place by means of the blending of the fibres of its anterior portion with those of the orbicularis palpebrarum, corrugator supercilii, levator labii supe- rioris aleeque nasi, and pyramidalis nasi. The muscle is fleshy in front over the frontal bone and behind over the occipital, the two por- tions being connected by a broad aponeurosis. The two muscles together with their aponeurosis cover the whole of the vertex of the skull, hence their designation galea capitis; they are loosely adherent to the pericranium, but very closely to the integument, particularly over the forehead. Relations.—This muscle is in relation by its external surface from before backwards, with the frontal and supra-orbital vessels, the supra-orbital and facial nerve, the temporal vessels and nerve, the occipital vessels and nerves, and with the integument, to which it is very closely adherent. Its wnder surface is attached to the peri- cranium by a loose areolar tissue which admits of considerable move- ment. Action.—To raise the eyebrows, thereby throwing the integument of the forehead into transverse wrinkles. Some: persons have the: power of moving the entire scalp upon the pericranium by means of these muscles. 2. Orbital group.—Orbicularis palpebrarum, Corrugator supercilii, Tensor tarsi. Dissection ——The dissection of the face is to be effected by con- tinuing the longitudinal incision of the vertex of the previous dissec- tion onwards to the tip of the nose, and thence downwards to the margin of the upper lip; then carry an incision along the margin of the lip to the angle of the mouth, and transversely across the face to the angle of the lower jaw. Lastly, divide the integument in front of the external ear upwards to the transverse incision which was made for exposing the occipito-frontalis. Dissect the integument and superfi- cial fascia carefully from the whole of the region included by these incisions, and the present with the two following groups of muscles will be brought into view. : The OrBicuLARIS PALPEBRARUM is a sphincter muscle, surround- 168 ORBICULARIS PALPEBRARUM. ing the orbit and eyelids. It arises from the internal angular process of the frontal bone, from the nasal process of the superior maxillary, and from a short tendon’ (tendo oculi) which extends between the nasal process of the superior maxillary bone, and the inner extremities of the tarsal cartilages of the eyelids. The fibres encircle the orbit and eyelids, forming a broad and thin muscular plane, which is ixserted into the lower border of the tendo oculi and into the nasal process of the superior maxillary bone. Upon the eyelids the fibres are thin and pale, and possess an involuntary action. The tendo oculi, in ad- dition to its insertion into the nasal process of the superior maxillary bone, sends a*process inwards which expands over the lachrymal sac, and is attached to the ridge of the lachrymal bone: this is the reflect- ed aponeurosis of the tendo oculi. - Relations.—By its superficial surface it is closely adherent to the integument from which it is separated over the eyelids by a loose areolar tissue. By its deep surface it lies in contact above with the upper border of the orbit, with the corrugator supercilii muscle, and with the frontal and supra-orbital vessels and supra-orbital nerve 5 below, with the lachrymal sac, with the origins of the levator labii superioris alzeque nasi, levator labii superioris proprius, zygomaticus major and minor muscles, and malar bone ; and eaternally with the — temporal fascia. Upon the eyelids it is in relation with the broad tarsal ligament and tarsal cartilages, and by its upper border gives at- tachment to the occipito-frontalis muscle. The CorruGaTorR SupeErcitu is a small narrow and_ pointed muscle, situated immediately above the orbit and beneath the upper segment of the orbicularis palpebrarum muscle. It arises from the inner extremity of the superciliary ridge, and is inserted into the under surface of the orbicularis palpebrarum at a point corresponding with the middle of the superciliary arch. Relations.—By its superficial surface, with the pyramidalis nasi, occipito-frontalis and orbicularis palpebrarum muscle ; and by its deep surface, with the supra-orbital vessels and nerve. The Tensor Tarsi (Horner’s * muscle) is a thin plane of muscular fibres, about three lines in breadth and six in length. It is best dis- sected by separating the eyelids from the eye, and turning them over the nose without disturbing the tendo oculi; then dissect away the small fold of mucous membrane called plica semilunaris, and some loose cellular tissue under which the muscle is concealed. It arises from the orbital surface of the lachrymal bone, and passing across the lachrymal sac divides into two slips, which are inserted into the lachrymal canals as far as the puncta. Actions.—The palpebral portion of the orbicularis acts involuntarily in closing the lids, and from the greater curve of the upper lid, upon that principally. The entire muscle acts as a sphincter, drawing at * W. E. Horner, M.D. Professor of Anatomy in the the ee of Pennsyl- vania. The notice of this muscle is contained in a work published in Philadel- phia in 1827, entitled ‘‘ Lessons in Practical Anatomy.’’ OCULAR GROUP. 169 the same time, by means of its osseous attachment, the integument and lids inwards towards the nose. The corrugatores superciliorum draw the eyebrows downwards and inwards, and produce the vertical wrinkles of the forehead. The ¢ensor tarsi, or lachrymal muscle, draws the extremities of the lachrymal canals inwards, so as to place the puncta in the best position for receiving the tears. It serves also to keep the lids in relation with the surface of the eye, and compresses the lachrymal sac. Dr. Horner is acquainted with two persons who have the voluntary power of drawing the lids inwards by these muscles so as to bury the puncta in the angle of the eye. 3. Ocular growp.—Levator palpebre, Rectus superior, Rectus inferior, Rectus internus, Rectus externus, Obliquus superior, Obliquus inferior. Dissection.—To open the orbit (the calvarium and brain having been removed) the frontal bone must be sawn through at the inner extremity of the orbital ridge ; and, externally, at its outer extremity. The roof of the orbit may then be comminuted by a few light blows with the hammer ; a process easily accomplished, on account of the Fig. 83.* * The muscles of the eyeball; the view is taken from the outer side of the right orbit. 1. A small fragment of the sphenoid bone around the entrance of the optic nerve into the orbit. 2. The optic nerve. 3. The globe of the eye. 4. The levator palpebree muscle. 5. The superior oblique muscle. 6. Its cartilaginous pulley. 7. Its reflected tendon. 8. The inferior oblique muscle, the small square knob at its commencement is a piece of its bony origin broken off. 9. The superior rectus. 10. The internal rectus almost concealed by the optic nerve. 11. Part of the external rectus, shewing its two heads of origin. 12. The extremity of the external rectus at its insertion ; the intermediate portion of the muscle having been removed. 13. The inferior rectus. 14. The tunica albuginea, formed by the expansion of the tendons of the four recti. Pcs leat: EE 4 170 OCULAR GROUP. thinness of the orbital plate of the frontal bone and lesser wing of the sphenoid. The superciliary portion of the orbit may now be driven . forwards by a smart blow, and the external angular process and ex- ternal wall of the orbit outwards in the same manner; the broken fragments of the roof of the orbit should then be removed. By this means the periosteum will be exposed unbroken and undisturbed. Remove the periosteum from the whole of the upper surface of the exposed orbit, and examine the parts beneath. The LevaTor PALPEBRz is a long, thin, and triangular muscle ; situated in the upper part of the orbit on the middle line ; it arises ZZe- from the upper margin of the optic foramen, and from the fibrous 34 e2an-~€sheath of the optic nerve, and is inserted into the upper border of the Prete - oie superior tarsal cartilage. Relations—By its upper surface with the fourth nerve, the supra- orbital nerve and artery, the periosteum of the orbit, and in front with the inner surface of the broad tarsal ligament. By its wader surface it rests upon the superior rectus muscle, and the globe of the eye ; it receives its nerve and artery by this aspect, and in front is covered for a short distance by the conjunctiva. The Recrus Superior (attollens) arises from the upper margin of the optic foramen, and from the fibrous sheath of the optic nerve, and is inserted into the upper surface of the globe of the eye at a point somewhat more than three lines from the margin of the cornea. Relations.—By its upper surface with the levator palpebree muscle ; by the under surface with the optic nerve, the ophthalmic artery and nasal nerve, from which it is separated by a layer of fascia and by the adipose tissue of the orbit, and in front with the globe of the eye, the tendon of the superior oblique muscle being interposed. The Recrus INFERIoR (depressor) arises from the inferior margin of the optic foramen by a tendon (ligament of Zinn) which is common to it, the internal and the external rectus, and from the fibrous sheath of the optic nerve ; it is zxserted into the inferior surface of the globe of the eye at a little more than two lines from the margin of the cornea. Relations.—By its upper surface with the optic nerve, the inferior obiique branch of the third nerve, the adipose tissue of the orbit, and the under surface of the globe of the eye. By its wnder surface with the a of the floor of the orbit, and with the inferior oblique muscle. The Recrus InrErNus (adductor), the thickest and shortest of the straight muscles, arises from the common tendon, and from the fibrous sheath of the optic nerve ; and is inserted into the inner sur- face of the globe of the eye at two lines from the margin of the , cornea. Relutions.—By its internal surface with the optic nerve, the adipose tissue of the orbit and the eyeball. By its outer surface with the pe- riosteum of the orbit ; and by its epper border with the anterior and posterior ethmoidal vessels, the nasal and supra-trochlear nerve. ; " a | £ OCULAR GROUP, 171 The Recrus ExtrerNus (abductor), the longest of the straight muscles, arises by two distinct heads, one from the common tendon, the other with the origin of the superior rectus from the margin of the optic foramen ; the nasal, third and sixth nerves passing between its heads. It is inserted into the outer surface of the globe of the eye at a little more than two lines from the margin of the cornea. Relations.—By its internal surface with the third, the nasal, the sixth, and the optic nerve, the ciliary ganglion and nerves, the oph- thalmic artery and vein, the adipose tissue of the orbit, the inferior oblique muscle, and the eyeball. By its eaternal surface with the pe- riosteum of the orbit ; and by the upper border with the lachrymal vessels and nerve and the lachrymal gland. The recti muscles present several characters which are common to all; thus, they are thin, have each the form of an isosceles triangle, bear the same relation to the globe of the eye, and are inserted in a similar manner into the sclerotica, at about two lines from the cireum- ference of the cornea. The points of difference relate to thickness and length ; the internal rectus is the thickest and shortest, the external rectus the longest of the four, and the superior rectus the most thin. The insertion of the four recti muscles into the globe of the eye forms a tendinous expansion, whichis continued as far as the margin of the cornea, and is called the tunica albuginea. __.The Osriquus Superior (trochlearis) is a fusiform muscle arising from the margin of the optic foramen, and from the fibrous sheath of the optic nerve ; it passes forwards to the pulley beneath the internal angular process of the frontal bone ; its tendon is then reflected be- neath the superior rectus muscle, to the outer and posterior part of the globe of the eye, where it is inserted into the sclerotic coat, near the entrance of the optic nerve. The tendon is surrounded by a synovial membrane, while passing through the cartilaginous pulley. Relations.—By its superior surface with the fourth nerve, the supra- trochlear nerve, and with the periosteum of the orbit. By the in- Jerior surface with the adipose tissue of the orbit, the upper border of — rectus and the vessels and nerves in relation with that er. The Osiiquus InFeRI0R, a thin and narrow muscle, arises from the inner margin of the superior maxillary bone, immediately external to the lachrymal groove, and passes beneath the inferior rectus, to be inserted into the outer and posierior part of the eyeball, at about two lines from the entrance of the optic nerve. Relations.—By its superior surface with the inferior rectus muscle and with the eyeball; and by the inferior surface with the perios- teum of the floor of the orbit, and the external rectus muscle. According to Mr. Ferrall* the muscles of the orbit are separated > from the globe of the eyeball and from the structures immediately surrounding the optic nerve, by a distinct fascia, which is continuous * In a paper read before the Royal Society, on the 10th of June, 1841. Supftted, Feet tne seis fy Hing ff Oe * we’. 172 NASAL GROUP. with the broad tarsal ligament and with the tarsal cartilages. This fascia the author terms, the tunica vaginalis oculi,* it is pierced ante- -riorly for the passage of the six orbital muscles, by six openings through which the tendons of the muscles play as through pulleys. The use assigned to it by Mr. Ferrall is to protect the eyeball from the pressure of its muscles during their action. By means of this structure the recti muscles are enabled to impress a rotatory movement upon the eyeball ; and in animals provided with a retractor muscle, they also act as antagonists to its action. Actions.—The levator palpebre raises the upper eyelid. The four recti, acting singly, pull the eyeball in the four directions ; upwards, downwards, inwards, and outwards. Acting by pairs, they carry the eyeball in the diagonal of these directions, viz. upwards and inwards, upwards and outwards, downwards and inwards, or downwards and outwards. Acting all together, they directly retract the globe within the orbit The superior oblique muscle, acting alone, rolls the globe inwards and forwards, and carries the pupil outwards and downwards to the lower and outer angle of the orbit. The inferior oblique, act- ing alone, rolls the globe outwards and backwards, and carries the pupil outwards and upwards to the upper and outer angle of the eye. Both muscles acting together, draw the eyeball forwards, and give the pupil that slight degree of eversion which enables it to admit the largest field of vision. 4, Nasal Group.—Pyramidalis nasi, Compressor nasi, Dilatator naris. The PyramipaLis Nasi is a small pyramidal slip of muscular fibres sent downwards upon the bridge of the nose by the occipito- frontalis. It is inserted into the tendinous expansion of the compres- sores nasi. Relations.—By its upper surface with the integument ; by its wxder surface with the periosteum of the frontal and nasal bone. Its ouder border corresponds with the edge of the orbicularis palpebrarum, and its inner border with its fellow, from which it is separated by a slight interval. The Compressor Nast is a thin and triangular muscle ; it arises by its apex from the canine fossa of the superior maxillary bone, and spreads out upon the side of the nose into a thin tendinous ex- pansion, which is continuous across its ridge with the muscle of the opposite side. Relations.—By its superficial surface with the levator labii supe- rioris proprius, the levator labii superioris aleeque nasi, and the inte- gument ; by its deep swrface with the superior maxillary and nasal bone, and with the alar and lateral cartilages of the nose. * This fascia was first described by Mr. Dalrymple in his work on the “ Ana- tomy of the Human Eye.’’ 1834. SUPERIOR LABIAL GROUP. 173 The DiraTatTor Naris is a thin and indistinct muscular apparatus expanded upon the ala of the nostril, and consisting of an anterior and a posterior slip. The anterior slip (levator proprius alz nasi anterior) extends between the lateral and alar cartilage at about midway be- tween the tip and the attached margin of the nose. The posterior slip (levator proprius ale nasi posterior) is attached above to the margin of the nasal process of the superior maxillary bone, and below to the small cartilages of the ala nasi. These muscles are difficult of dissection from the close adherence of the integument to the nasal car- tilages, Actions.—The pyramidalis nasi, as a point of attachment of the occipito-frontalis, assists that muscle in its action: it also draws down the inner angle of the eyebrow, and by its insertion fixes the aponeu- rosis of the compressores nasi. The compressores nasi appear to act in expanding rather than in compressing the nares ; hence probably the compressed state of the nares from paralysis of these muscles in the last moments of life, or in compression of the brain. The use of. the dilatator naris is expressed in its name. 5. Superior Labial Group. —Orbicularis oris, Levator labii superioris aleeque nasi, Levator labii superioris proprius, Levator anguli oris, Zygomaticus major, Zygomaticus minor, Depressor labii superioris aleeque nasi. The OrsicuLaris Oris is a sphincter muscle, completely surround- ing the mouth, and possessing-consequently neither origin nor inser- tion. It is composed of two thick semicircular planes of fibres, which embrace the rima of the mouth, and interlace at their extremities, where they are continuous with the fibres of the buccinator, and of the other muscles connected with the angle of the mouth. The upper segment is attached by means of a small muscular fasciculus (naso- labialis) to the columna of the nose ; and other fasciculi connected with both segments and attached to the maxillary bones are termed ** accessorii.”” * Relations—By its superficial surface with the integument of the lips with which it is closely connected. By its deep surface with the mucous membrane of the mouth, the labial glands and coronary arteries being interposed. By its circumference with the numerous muscles which move the lips, and by the inner border with the mucous mem- brane of the rima of the mouth. The Levator Lasu SurEerioris ALZQque Nast is a thin trian- gular muscle ; it arises from the upper part of the nasal process of the superior maxillary bone ; and, becoming broader as it descends, is in- serted by two distinct portions into the ala of the nose and upper lip. Relations.—By its superficial surface with a part of the orbicularis 174 LEVATOR LABIL SUPERIORIS. palpebrarum muscle, the facial artery, and the integument. By its deep surface with the superior maxillary bone, compressor nasi, alar - -eartilage, and with a muscular fasciculus attached only to the bone, and thence called musculus anomalus. _ The Leyaror Lasu Superrioris Proprius is a thin quadrilateral muscle: it arises from the lower border of the orbit, and passing ob- liquely downwards and inwards, is inserted into the integument of the upper lip ; its deep fibres being blended with those of the orbicularis. Relations.—By its superficial surface with the lower segment of the orbicularis palpebrarum, with the facial artery, and with the integu- ment. By its deep surface with the origins of the compressor nasi and levator anguli oris muscle, and with the infra-orbital artery and nerve. The Levator ANGuLI Oris arises from the canine fossa of the superior maxillary bone, and passes outwards to be inserted into the angle of the mouth, intermingling its fibres with those of the orbicu- laris, zygomatici, and depressor anguli oris. Relations.—By its superficial surface with the levator labii supe- rioris proprius, the branches of the infra-orbital artery and nerve, and inferiorly with the integument. By its deep surface with the superior maxillary bone and buccinator muscle. The ZyGomaTic muscles are two slender fasciculi of fibres which arise from the malar bone, and are énserted into the angle of the mouth, where they are continuous with the other muscles attached to this part. The zygomaticus minor is situated in front of the major, and is continuous at its insertion with the levator labii superioris proprius ; it is not unfrequently wanting. Relations.—The zygomaticus major muscle is in relation by its super- ficial surface with the lower segment of the orbicularis palpebrarum above, and the fat of the cheek and integument for the rest of its ex- tent. By its deep surface with the malar bone, the masseter, and buc- cinator muscle, and the facial vessels. The zygomaticus minor being in front of the major, has no relation with the masseter muscle, while inferiorly it rests upon the levator anguli oris. The Derressor Lasu SupErionis ALZQuE Nast (myrtiformis) is seen by drawing upwards the upper lip, and raising the mucous membrane. It is a small oval slip of muscle, situated on each side of the frenum, arising from the incisive fossa, and passing upwards to be inserted into the upper lip and into the ala and columna of the nose. This muscle is continuous by its outer border with the edge of the compressor nasi. Relations. —By its superficial surface with the mucous membrane of the mouth, the orbicularis oris and levator labii superioris aleeque nasi muscle ; and by its deep surface with the superior maxillary bone. Actions.—The orbicularis oris produces the direct closure of the lips by means of its continuity at the angles of the mouth, with the fibres of the buccinator. When acting singly in the forcible closure of the mouth, the integument is thrown into wrinkles in consequence of its firm connection with the surface of the muscle. The levator labii INFERIOR LABIAL GROUP. 175 superioris alzeque nasi lifts the upper lip with the ala of the nose, and expands the opening of the nares. The depressor labii superioris alzeque nasi is the antagonist to this muscle, drawing the upper lip and ala of the nose downwards, and contracting the opening of the nares. The levator labii superioris proprius is the proper elevator of the upper lip ; acting singly, it draws the lip a little to one side. The levator anguli oris lifts the angle of the mouth and draws it inwards, while the zygomatic pull it upwards and outwards, as in laughing. 6. Inferior Labial Group.—Depressor labii inferioris, Depressor anguli oris, Levator labii inferioris. Dissection—To dissect the inferior labial region continue the vertical section from the margin of the lower lip to the point of the chin. Then carry an incision along the margin of the lower jaw to its angle. Dissect off the integument and superficial fascia from the _ whole of this surface, and the muscles of the inferior labial region will be exposed. The DzPREssoR LABI INFERIORIS (quadratus menti) arises from : the oblique line by the side of the symphysis of the lower jaw, and passing upwards and inwards is inserted into the orbicularis muscle and integument of the lower lip. _ Relations,—By its superficial surface with the platysma myoides, part of the depressor anguli oris, and with the integument of the chin with which it is closely connected. By the deep surface with the le- vator labii inferioris, the labial glands and mucous membrane of the lower lip, and with the mental nerve and artery. The DzpREssOR ANGULI ORIS (triangularis oris) is a triangular plane of muscle arising by a broad base from the external oblique ridge of the lower jaw, and inserted by its apex into the angle of the mouth, where it is continuous with the levator anguli oris and zygo- maticus major. Relations.—By its superficial surface with the integument ; and by its deep surface with the depressor labii inferioris, the buccinator and the branches of the mental nerve and artery. The LEVATOR LABII INFERIORIS (levator menti) is a small conical slip of muscle arising from the incisive fossa of the lower jaw, and in- serted into the integument of the chin. It is in relation with the mucous membrane of the mouth, with its fellow, and with the de- pressor labii inferioris. Actions.—The depressor labii inferioris draws the lower lip directly downwards, and at the same time a little outwards. The depressor anguli oris, from the radiate direction of its fibres, will pull the angle of the mouth either downwards and inwards, or downwards and out- wards, and be expressive of grief ; or acting with the levator anguli oris and zygomaticus major, it will draw the angle of the mouth directly backwards. The levator labii inferioris raises and protrudes the integument of the chin. v 176 MAXILLARY GROUP. 7. Mazxillary group.—Masseter, * Temporalis, Buccinator, Pterygoideus externus, Pterygoideus internus. Dissection.—The masseter has been already exposed by the pre- ceding dissection. “et 3 Sp Shea The MasseTeEr (“aecdowas, to chew,) is a short, thick and some- Meppoterc? quadrilateral aise ng composed of two planes of fibres, super- y a Araw® ficial and deep. The superficial layer arises by a strong aponeurosis 2 o-2ee v.-0er-from the tuberosity of the superior maxillary bone, the lower border plier~ f of the malar bone and zygoma, and passes backwards to be inserted A hi’ into the ramus and angle of the inferior maxilla. The deep layer arises from the posterior part of the zygoma, and passes forwards, to a * be inserted into the upper half of the ramus. This muscle is tendinous and muscular in its structure. Relations.—By its external surface with the zygomaticus major and risorius Santorini muscle, the parotid gland and Stenon’s duct, the transverse facial artery, the pes anserinus and the integument. By its internal surface with the temporal muscle, the buccinator, from which it is separated by a mass of fat, and with the ramus of the lower jaw, By its posterior border with the parotid gland ; and by the anterior border with the facial artery and vein. Dissection Make an incision along the upper border of the zygoma, for the purpose of separating the temporal fascia from its attachment. Then saw through the zygomatic process of the malar bone, and through the root of the zygoma, near to the meatus audi- torius. Draw down the zygoma, and with it the origin of the mas- seter, and dissect the latter muscle away from the ramus and angle of the inferior maxilla. Now remove the temporal fascia from the rest of its attachment, and the whole of the temporal muscle will be exposed. The TEMPORAL is a broad and radiating muscle occupying a consi- derable extent of the side of the head and filling the temporal fossa. ite~o one+ff is covered in by a very dense fascia (temporal fascia) which is tyres w+ fe attached along the temporal ridge on the side of the skull, extending «242 ->~ -F from the external angular process of the frontal bone to the mastoid | are>r€ portion of the temporal ; inferiorly, it is connected to the upper border of the zygoma. The muscle arises by tendinous fibres from the whole length of the temporal ridge, and by muscular fibres from the temporal fascia and entire surface of the temporal fossa. Its fibres converge to a strong and narrow tendon, which is inserted into the apex of the coronoid process, and for some way down upon its inner surface. Relations.—By its external surface with the temporal fascia, which separates it from the attollens and attrahens aurem muscle, the tem- poral vessels and nerves ; and with the zygoma and masseter. By its internal surface with the bones forming the temporal fossa, the exter- Pa ee Oh eee (> ptt nee ae > BUCCINATOR.—PTERYGOIDEL. 177 nal pterygoid muscle, a part of thé buccinator, and the internal maxil- lary artery with its deep temporal branches. By sawing through the coronoid process near to its base, and pull- ing it upwards, together with the temporal muscle, which may be dis- sected from the fossa, we obtain a view of the entire extent of the buccinator and of the external pterygoid muscle. The BuccrnaTor (buccina, a trumpet), the trumpeter’s muscle, arises oe from the alveolar process of the superior maxillary and from the ex- ternal oblique line of the inferior maxillary bone, as far forward as the second bicuspid tooth, and from the pterygo-maxillary ligament. “-7 Af This ligament is the raphé of union between the buccinator and supe- 4 rior constrictor muscle, and is attached by one extremity to the hamu- lar process of the internal pterygoid plate, and by the other to th extremity of the molar ridge. The fibres of the muscle converge to- wards the angle of the mouth where they cross each other, the superior being continuous with the inferior segment of the orbicularis oris, and the inferior with the superior segment. The muscle is in- vested externally by a thin fascia. Relations—By its external surface, posteriorly with a large and rounded mass of fat, which separates the muscle from the ramus of the lower jaw, the temporal, and the masseter ; anteriorly with the risorius Santorini, the zygomatici, the levator anguli oris, and the depressor anguli oris. It is also in relation with a part of Stenon’s duct which pierces it opposite the second molar tooth of the upper jaw, with the transverse facial artery, the branches of the facial and buccal nerve, and the facial artery and vein. By its internal surface with the buccal glands and mucous membrane of the mouth. The EXTERNAL PTERYGOID is a short and thick muscle, broader at its origin than at its insertion. It arises by two heads, one from the 9 pterygoid ridge on the greater ala of the sphenoid ; the other from the a external pterygoid plate and tuberosity of the palate bone. The fibres nv conse y pass backwards to be inserted into the neck of the lower jaw and the” 7“ ‘ interarticular fibro-cartilage. The internal maxillary artery frequently passes between the two heads of this muscle. Relations.—By its eaternal surface with the ramus of the lower jaw, the temporal muscle, and the internal maxillary artery ; by its internal surface with the internal pterygoid muscle, internal lateral ligament of the lower jaw, arteria meningea media, and inferior maxillary nerve ; and by its wpper border with the muscular branches of the inferior maxillary nerve ; the internal maxillary artery passes between the two heads of this muscle, and its lower origin is pierced by the buccal nerve. The external pterygoid muscle must now be removed, the ramus of the lower jaw sawn through its lower third, and the head of the bone dislocated from its socket and withdrawn, for the purpose of seeing the pterygoideus internus. The INTERNAL PTERYGOID is a thick quadrangular muscle. It B ‘ arises from the pterygoid fossa and descends obliquely backwards, to “3 * ; be inserted into the ramus and angle of the lower jaw: it resembles4z, 25- N fhostisce Gwe 178 AURICULAR GROUP. the masseter in appearance and direction, and was named by Winslow the internal masseter, _ Relations—By its external surface with the external pterygoid, the inferior maxillary nerve and its branches, the internal maxillary artery and branches, the internal lateral ligament, and the ramus of the lower jaw. By its internal swrface with the tensor palati, superior constrictor and fascia of the pharynx, and by its posterior border with the parotid gland. Fig. 84.* Actions.—The maxillary muscles are the active agents in mastica- tion, and form an apparatus beautifully fitted for that office. The buccinator cireumscribes the cavity of the mouth, and with the aid of the tongue keeps the food under the immediate pressure of the teeth. By means of its connection with the superior constrictor, it shortens the cavity of the pharynx, from before backwards, and becomes an im- portant auxiliary in deglutition. The temporal, the masseter, and the internal pterygoid are the bruising muscles, drawing the lower jaw against the upper with great force. The two latter by the obliquity of their direction, assist the external pterygoid in grinding the food by carrying the lower jaw forward upon the upper ; the jaw being brought back again by the deep portion of the masseter and posterior fibres of the temporal. The whole of these muscles, acting in succession, pro- duce a rotatory movement of the teeth upon each other, which, with the direct action of the lower jaw against the upper, effects the proper mastication of the food. 8. Auricular Group.—Attollens aurem, Attrahens aurem, Retrahens aurem. * The two pterygoid muscles. The zygomatic arch and the greater part of the ramus of the lower jaw have been removed in order to bring these muscles into view. 1. The sphenoid origin of the external pterygoid muscle. 2. Its pterygoid origin. 3. The internal pterygoid muscle. eta ne aD eee wt MUSCLES OF THE NECK. 179 Dissection.—The three small muscles of the ear may be exposed by removing a square of integument from around the auricula. This operation must be performed with care, otherwise the muscles, which are extremely thin, will be raised with the superficial fascia. They are best dissected by commencing with their tendons, and thence proceeding in the course of their radiating fibres. The ATTOLLENS AUREM (superior auris), the largest of the three, is a thin triangular plane of muscular fibres arising from the edge of the aponeurosis of the occipito-frontalis, and inserted into the upper part of the concha. It is in relation by its external surface with the integument, and by the internal with the temporal aponeurosis. The ATTRAHENS AUREM (anterior auris), also triangular, arises from the edge of the aponeurosis of the occipito-frontalis, and is én- serted into the anterior part of the helix, covering in the anterior and posterior temporal arteries. It is iz relation by its external surface with the integument ; and by the internal with the temporal aponeurosis and with the temporal artery and veins. The RETRAHENS AUREM (posterior auris), arises by three or four muscular slips from the mastoid process. They are inserted into the posterior surface of the concha. - It is tn relation by its external surface with the integument, and by its internal surface with the mastoid portion of the temporal bone. Actions.—The muscles of the auricular region possess but little action in man ; they are the analogues of important muscles in brutes. Their use is sufficiently explained in their names, MUSCLES OF THE NECK. The muscles of the neck may be arranged into eight groups corres- ponding with the natural divisions of the region ; they are the— 1. Superficial group. 2. Depressors of the os hyoides and larynx, . Elevators of the os hyoides and larynx. . Lingual group. . Pharyngeal group. . Soft palate group. . Prevertebral group. . Proper muscles of the larynx. And each of these groups consists of the following muscles :—viz. SONIC) Or ® Go 1, Superficial Group. 2. Depressors of the os Platysma-myoides, hyoides and larynx, Sterno-cleido-mastoideus. Sterno-hyoideus, Sterno-thyroideus, Thyro-hyoideus, Omo-hyoideus. 180 PLATYSMA MYOIDES. 3. Elevators of the os 6. Muscles of the soft Palate. ‘ renee one eran Leyator palati, Digastricus, Tensor palati, Stylo-hyoideus, Azygos uvule, Mylo-hyoideus, Palato-glossus, Genio-hyoideus, Palato-pharyngeus. Genio-hyo-glossus. 7. Prevertebral Group. Rectus anticus major, Rectus anticus minor, 4, Muscles of the Tongue. Genio-hyo-glossus, tooale Scalenus anticus, ? . Stylo-glossus, Scalenus posticus, Palato-glossus. Longus colli. 5. Muscles of the Pharynx. 8. Muscles of the Larynx. Constrictor inferior, Crico-thyroideus, Constrictor medius, Crico-aryteenoideus, posticus, Constrictor superior, Crico-arytznoideus, lateralis, Stylo-pharyngeus, Thyro-arytznoideus, Palato-pharyngeus. Aryteenoideus. Dissection —The dissection of the neck should be commenced by making an incision along the middle line of its fore part from the chin to the sternum, and bounding it superiorly and inferiorly by two transverse incisions ; the superior one being carried along the margin of the lower jaw, and across the mastoid process to the tubercle on the occipital bone, the inferior one along the clavicle to the acromion process. The square flap of integument thus included should be turned back from the entire side of the neck, which brings into view the superficial fascia, and on the removal of a thin layer of superficial fascia the platysma myoides will be exposed. The PLATYSMA MYOIDES (rAaris, wis ¢id0s, broad muscle-like la- mella), is a thin plane of muscular fibres, situated between the two layers of the superficial cervical fascia; it arises from the integument over the pectoralis major and deltoid muscles, and passes obliquely upwards and inwards along the side of the neck to be zserted into the side of the chin, oblique line of the lower jaw, the angle of the mouth, and into the cellular tissue of the face. The most anterior fibres are continuous beneath the chin, with the muscle of the opposite side ; the next interlace with the depressor anguli oris, and depressor labii inferioris, and the most posterior fibres are disposed in a transverse: direction across the side of the face, arising’ in the cellular tissue covering the parotid gland, and inserted into the angle of the mouth, constituting the risorius Santorini, The entire muscle is analogous to the cutaneous muscle of brutes, the panniculus carnosus. Relations.—By its external surface with the integument, with which it is closely adherent below, but loosely above. By its internal surface, STERNO-CLEIDO-MASTOIDEUS. 181 below the clavicle, with the pectoralis major and deltoid ; in the neck with the external jugular vein and deep cervical fascia ; on the face, with the parotid gland, the masseter, the facial artery and vein, the buccinator, the depressor anguli oris, and the depressor labii in- ferioris, On raising the platysma throughout its whole extent, the sterno- mastoid is brought into view. Fig. 85.* The STERNO-CLEIDO-MASTOID is the large oblique muscle of the neck, ' and is situated between two layers of the deep cervical fascia. It arises as implied in its name from the sternum and clavicle (xAsdiov), and passes obliquely upwards and backwards to be inserted into the * The muscles of the anterior aspect of the neck ; on the left side the super- ficial muscles are seen, and on the right the deep. 1. The posterior belly of the digastricus muscle. 2. Its anterior belly. The aponeurotic pulley, through which its tendon is seen passing, is attached to the body of the os hyoides 3. 4. The stylo-hyoideus muscle, transfixed by the posterior belly of the digastri- cus. 5. The mylo-hyoideus. 6. The genio-hyoideus. 7. The tongue. 8. The hyo-glossus. 9. The stylo-glossus. 10, The stylo-pharyngeus. 11. The sterno-mastoid muscle. 12. Its sternal origin. 13. Its clavicular origin. 14. The sterno-hyoid. 15 The sterno-thyroid of the right side. 16. The thyro- hyoid. 17. The hyoid portion of the omo-hyoid. 18,18. Its scapular por- tion ; on the left side, the tendon of the muscle is seen to be bound down by a portion of the deep cervical fascia. 19. The clavicular portion of the trapezius. 20. The scalenus anticus, of the right side. 21. The scalenus posticus. 182 DEPRESSORS OF THE OS HYOIDES AND LARYNX. mastoid process and into the superior curved line of the occipital bone. The sternal portion arises by a rounded tendon, increases in breadth as it ascends, and spreads out to a considerable extent at its insertion. The clavicular portion is broad and fleshy, and separate from the sternal portion below, but becomes gradually blended with its posterior surface as it ascends. Relations.— By its superficial surface with the integument, the pla- tysma myoides, the external jugular vein, superficial branches of the anterior cervical plexus of nerves, and the anterior layer of the deep cervical fascia. By its deep surface with the deep layer of the cervical fascia; with the sterno-clavicular articulation, the sterno-hyoid, sterno-thyroid, omo-hyoid, scaleni, levator anguli scapulz, splenii, and the posterior belly of the digastric muscle; with the phrenic nerve, and the posterior, and supra-scapular artery ; with the deep lymphatic glands, the sheath of the common carotid and internal jugular vein, the descendens noni nerve, the external carotid artery and its posterior branches, the commencement of the internal carotid artery ; with the cervical plexus of nerves, the pneumogastric, the spinal accessory, the hypoglossal, the sympathetic and the facial nerve, and with the parotid gland. It is pierced on this aspect by the spinal accessory nerve and by the branches of the mastoid artery. The anterior border of the muscle is the posterior boundary of the great anterior triangle, the other two boundaries being the middle line of the neck in front, and the lower border of the jaw above. It is the guide to the operations for the ligature of the common carotid artery and arteria innominata, and for cesophagotomy. ‘The posterior border is the anterior boundary of the great posterior triangle; the other two boundaries being the anterior border of the trapezius behind, and the clavicle below. Actions.—The platysma produces a muscular traction on the integu- ment of the neck, which prevents it from falling so flaccid in old persons as would be the case if the extension of the skin were the mere result of elasticity. It draws also upon the angle of the mouth, and is one of the depressors of the lower jaw. The transverse fibres draw the angle of the mouth outwards and slightly upwards. The sterno- mastoid muscles are the great anterior muscles of connection between the thorax and the head. Both muscles acting together bow the head directly forwards. The clavicular portions, acting more forcibly than the sternal, give stability and steadiness to the head in supporting great weights. Either muscle acting singly would draw the head towards the shoulder of the same side, and carry the face towards the opposite side. Second Group.—Depressors of the Os Hyoides and Larynx. Sterno-hyoid, Sterno-thyroid, Thyro-hyoid, Omo-hyoid. Dissection.—These muscles are brought into view by removing the oS litical hae # STERNO-HYOIDEUS.—OMO-HYOIDEUS. 183 deep fascia from off the front of the neck between the two sterno- mastoid muscles. The omo-hyoid to be seen in its whole extent re- quires that the sterno-mastoid muscle should be divided from its origin and turned aside. The SrEeRNo-HyomweEvs, is a narrow riband-like muscle, arising from the posterior surface of the first bone of the sternum and inner extremity of the clavicle. It is inserted into the lower border and posterior surface of the body of the os hyoides. The sterno-hyoidei are separated by a considerable interval at the root of the neck, but approach each other as they ascend: they are frequently traversed by a tendinous intersection. Relations.—By its eaternal surface with the deep cervical fascia, the platysma myoides and sterno-mastoid muscle ; by its internal surface with the sterno-thyroid, and thyro-hyoid muscle, and the superior thyroid artery. ; The Srerno-rHyRowevs, broader than the preceding beneath which it lies, arises from the posterior surface of the upper bone of the sternum, and from the cartilage of the first rib; it is imserted into the oblique line on the great ala of the thyroid cartilage. The inner borders of these muscles lie in contact along the middle line, and they are generally marked by a tendinous intersection at their lower part. Relations.—By its external surface with the sterno-hyoid, omo- hyoid, and sterno-mastoid muscle ; by its internal surface, with the trachea and inferior thyroid veins, with the thyroid gland, the lower part of the larynx, the sheath of the common carotid artery and internal jugular vein, with the subclavian vein and vena innominata, and on the right side with the arteria innominata. The middle thy- roid vein lies along its inner border. The Tuyro-HyomEws is the continuation upwards of the sterno- thyroid muscle. It arises from the oblique line on the thyroid carti- lage, and is inserted into the lower border of the body and great cornu of the os hyoides. Relations.—By its external surface with the sterno-hyoid and omo- hyoid muscle ; by its internal surface with the great ala of the thyroid cartilage, the thyro-hyoidean membrane, and the superior laryngeal artery and nerve. The Omo-HyornEus (aes, shoulder) is a double-bellied muscle passing obliquely across the neck from the scapula to the os hyoides ; it forms an obtuse angle behind the sterno-mastoid muscle, and is retained in that position by means of a process of the deep cervical fascia which is connected to the inner border of its tendon. It arises from the upper border of the scapula, and from the transverse liga- ment of the supra-scapular notch, and is inserted into the lower border of the body of the os hyoides. Relations.—By its superficial surface with the trapezius, the sub- clavius and clavicle, the deep cervical fascia and platysma myoides, the sterno-mastoid, and the integument. By its deep surface with the 184 ELEVATORS OF THE OS HYOIDES. brachial plexus, the scaleni muscles, the phrenic nerve, the sheath of the common carotid artery and jugular vein, the descendens noni nerve, the sterno-thyroid, and thyro-hyoid muscle, and the sterno-hyoid at its insertion. The scapular portion of the muscle divides the great posterior triangle into a superior or occipital triangle ; and an inferior or subclavian triangle, which contains the subclavian artery and bra- chial plexus of nerves; the other two boundaries of the latter being the sterno-mastoid in front and the clavicle below. The hyoid por- tion of the muscle, divides the great anterior triangle into an inferior carotid triangle situated below the muscle, and into a superior triangle which lies above the muscle and is again subdivided by the digas- tricus into the submazillary triangle and the superior carotid triangle. The other two boundaries of the inferior carotid triangle, are the middle line of the neck in front and the anterior border of the sterno- mastoid behind. The other boundaries of the superior carotid triangle are the posterior belly of the digastricus muscle above and the ante- rior border of the sterno-mastoid behind. Actions.—The four muscles of this group are the depressors of the os hyoides and larynx. The three former drawing these parts downwards in the middle line, and the two omo-hyoidei regulating their traction to the one or other side of the neck, according to the position of the head. The omo-hyoid muscles by means of their con- nection with the cervical fascia are rendered tensors of that portion of the deep cervical fascia which covers in the lower part of the neck, between the two sterno-mastoid muscles. Third Group.—Elevators of the Os Hyoides. Digastricus, Stylo-hyoid, Mylo-hyoid, Genio-hyoid, Genio-hyo-glossus. Dissection.—These are best dissected by placing a high block be- neath the neck, and throwing the head backwards. The integument has been already dissected away, and the removal of the cellular tissue and fat brings them clearly into view. The Digasrricus (33s, twice, yaork belly) is a small muscle situ- ated immediately beneath the side of the body of the lower jaw ; it is fleshy at each extremity, and tendinous in the middle. It arises from the digastric fossa, upon the inner side of the mastoid process of the temporal bone, and is izserted into a depression on the inner side of the lower jaw, close to the symphysis. The middle tendon is held in connection with the body of the os hyoides by an aponeurotic loop, through which it plays as through a pulley ; the loop being lubricated by a synovial membrane. A thin layer of aponeurosis is given off from the tendon of the digastricus at each side, which is connected with the body of the os hyoides and forms a strong plane of fascia nant eee 18 Oy 2 ey ne STYLO-HYOIDEUS.—GENIO-HYOIDEUS. 185 between the anterior portions of the two muscles. This fascia is named the supra-hyoidean. Relations.—By its superficial surface with the platysma myoides, the sterno-mastoid, the anterior fasciculus of the stylo-hyoid muscle, the parotid gland, and submaxillary gland. By its deep surface with the styloid muscles, the hyo-glossus, the mylo-hyoid muscle, the ex- ternal carotid artery, the lingual and the facial arteries, the in- ternal carotid artery, the jugular vein, and the hypoglossal nerve. The digastric muscle forms the two inferior boundaries of the sub- maxillary triangle, the superior boundary being the side of the body of the lower jaw. In the posterior half of the submaxillary triangle are situated the submaxillary gland and the facial artery. The SryLo-HyorpEvs is a small and slender muscle situated in immediate relation with the posterior belly of the digastricus muscle, being pierced by its tendon. It arises from the middle of the styloid process, and is inserted into the body of the os hyoides near the middle line. Relations.—By its superficial surface with the posterior belly of the digastricus, the parotid gland and sub-maxillary gland ; its deep re- lations are similar to those of the posterior belly of the digastricus. The digastricus and stylo-hyoideus must be removed from their con- nection with the lower jaw and os hyoides, and turned aside in order _to see the next muscle. The My.o-nyorpeEvs (van, mola, 7. e. attached to the molar ridge of the lower jaw) is a broad triangular plane of muscular fibres, form- ing, with its fellow of the opposite side, the inferior wall or floor of the mouth. It arises from the molar ridge on the lower jaw, and proceeds obliquely inwards to be inserted into the ruphé of the two muscles and into the body of the os hyoides; the raphé is sometimes deficient at its _ anterior part. Relations.—By its superficial or inferior surface, with the platysma myoides, the digastricus, the supra-hyoidean fascia, the submaxillary gland and the submental artery. By its deep or superior surface, with the genio-hyoideus, the genio-hyo-glossus, the hyo-glossus, the stylo- glossus, the gustatory nerve, the hypoglossal nerve, Wharton’s duct, the sublingual gland, and the mucous membrane of the floor of the mouth. After the mylo-hyoideus has been examined, it should be cut away from its origin and insertion, and completely removed. The view of the next muscles would also be greatly improved by dividing the lower jaw on the near side of the symphysis, and drawing it outwards, or by removing it altogether if the ramus have been already cut across in dissecting the internal pterygoid muscle. The tongue may then be drawn out of the mouth by means of a hook. The GENIO-HYOIDEUS (+év¢0v, the chin) arises from a small tubercle upon the inner side of the symphysis of the lower jaw, and is inserted into the upper part of the body of the os hyoides. It is a short and slender muscle, very closely connected with the border of the following. 186 MUSCLES OF THE TONGUE. Relations.—By its superficial or inferior surface, with the mylo- hyoideus; by the deep or superior swrface with the lower border of _the genio-hyo-glossus. The Gern10-Hy0-GLOssuS (yAweca, the tongue) is a triangular muscle, narrow and pointed at its origin from the lower jaw, broad and fan-shaped at its attachment to the tongue. It arises from a tubercle immediately above that of the genio-hyoideus, and spreads out to be inserted into the whole length of the tongue, from its base to the apex, and into the body of the os hyoides. Relations.—By its inner surface with its fellow of the opposite side. By its outer surface with the mylo-hyoidéus, the hyo-glossus, the stylo-glossus, lingualis, the sublingual gland, the lingual artery, and the hypoglossal nerve. By its wpper border with the mucous membrane of the floor of the mouth, in the situation of the freenum lingue; and by the lower border with the genio-hyoideus. Actions.—The whole of this group of muscles acts upon the os hyoides when the lower jaw is closed, and upon the lower jaw when the os hyoides is drawn downwards, and fixed by the depressors of the os hyoides and larynx. The genio-hyo-glossus is, moreover, a muscle of the tongue ; its action upon that organ shall be considered with the next group. Fourth Group.— Muscles of the Tongue. * Genio-hyo-glossus, Hyo-glossus, Lingualis, Stylo-glossus, Palato-glossus. These are already exposed by the preparation we have just made ; there remains, therefore, only to dissect and examine them. The Genio-hyo-glossus, the first of these muscles, has been described with the last group. The Hyo-Giossus is a square-shaped plane of muscle, arising from the whole length of the great cornu and from the body of the os hyoides, and inserted between the stylo-glossus and lingualis into the side of the tongue. The direction of the fibres of that portion of the muscle which arises from the body is obliquely backwards ; and that from the great cornu obliquely forwards ; hence they are described by Albinus as two distinct muscles, under the names of the basio-glossus, and cerato-glossus, to which he added a third fasciculus, arising from the lesser cornu, and spreading along the side of the tongue, the chondro-glossus. The basio-glossus slightly overlaps the cerato- glossus at its upper part, and is separated from it by the transverse portion of the stylo-glossus. Relations.—By its eaternal surface with the digastric muscle, the stylo-hyoideus, stylo-glossus and mylo-hyoideus, with the gustatory nerve, the hypoglossal nerve, Wharton’s duct and the sublingual gland. By its internal surface with the middle constrictor of the pharynx, Ll LINGUALIS. 187 the lingualis, the genio-hyo-glossus, the lingual artery, and the glosso- pharyngeal nerve. The Lineuatis.—The fibres of this muscle may be seen towards the apex of the tongue, issuing from the interval between the hyo- Fig. 86.* glossus and genio-hyo-glossus; it is best examined by removing the preceding muscle. It consists of a small fasciculus of fibres, running longitudinally from the base, where it is attached to the os hyoides, to the apex of the tongue. It is in relation by its under surface with the ranine artery. * The styloid muscles and the muscles of the tongue. 1. A portion of the temporal bone of the left side of the skull, including the styloid and mastoid rocesses, and the meatus auditorius externus. 2,2. The right side of the ower jaw, divided at its Bar soe the left side having been removed. 3. The tongue. 4. The genio-hyoideus muscle. 5. The genio-hyo-glossus. 6. The hyo-glossus muscle; its basio-glossus portion. 7. Its cerato-glossus portion. 8. The anterior fibres of the lingualis issuing from between the hyo-glossus and genio-hyo-glossus. 9. The stylo-glossus muscle, with a small portion of the stylo-maxillary ligament. 10. The stylo-hyoid. 11. The stylo-pharyngeus muscle. 12. The os hyoides. 13. The thyro-hyoidean membrane. 14. The thyroid cartilage. 15. The thyro-hyoideus muscle arising from the oblique line on the thyroid cartilage. 16. The cricoid cartilage. 17. The crico-thyroidean membrane, through which the operation of laryngotomy is performed. 18. The trachea. 19. The commencement of the cesophagus. 188 MUSCLES OF THE PHARYNX. The Sry1o-GLossus arises from the apex of the styloid process, and from the stylo-maxillary ligament ; it divides upon the side of the tongue into two portions, one transverse, which passes transversely inwards between the two portions of the hyo-glosssus, and is lost among the transverse fibres of the substance of the tongue, and another longitudinal, which spreads out upon the side of the tongue as far as its tip. Relations.—By its external surface with the internal pterygoid muscle, the gustatory nerve, the parotid gland, sublingual gland, and the mucous membrane of the floor of the tongue. By its internal sur- face with the tonsil, the superior constrictor muscle of the pharynx, and the hyo-glossus muscle. The PALATo-GLossus passes between the soft palate, and the side of the base of the tongue, forming a projection of the mucous mem- brane, which is called the anterior pillar of the soft palate. Its fibres are lost superiorly among the muscular fibres of the palato-pharyngeus, and inferiorly among the fibres of the stylo-glossus upon the side of the tongue. This muscle with its fellow constitutes the constrictor isthmi faucium. Actions—The genio-hyo-glossus muscle effects several movements of the tongue, as might be expected from its extent. When the tongue is steadied and pointed by the other muscles, the posterior fibres of the genio-hyo-glossus would dart it from the mouth, while its anterior fibres would restore it to its original position. The whole length of the muscle acting upon the tongue, would render it concave along the ~ middle line, and form a channel for the current of fluid towards the pharynx, as in sucking. The apex of the tongue is directed to the roof of the mouth, and rendered convex from before backwards by the linguales. The hyo-glossi, by drawing down the sides of the tongue, render it convex along the middle line. It is drawn upwards at its base by the palato-glossi, and backwards or to either side by the stylo- glossi. Thus the whole of the complicated movements of the tongue may be explained, by reasoning upon the direction of the fibres of the muscles, and their probable actions. The palato-glossi muscles as- sisted by the uvula, have the power of closing the fauces completely, an action which takes place in deglutition. Fifth Group.—Museles of the Pharynx. Constrictor inferior, Constrictor medius, Constrictor superior, Stylo-pharyngeus, Palato-pharyngeus. Dissection—To dissect the pharynx, the trachea and cesophagus are to be cut through at the lower part of the neck, and drawn up- wards by dividing the loose cellular tissue which connects the pharynx to the vertebral column. The saw is then to be applied behind the ete ee —— ~~ > re oes! CONSTRICTOR MEDIUS.—CONSTRICTOR SUPERIOR. 189 styloid processes, and the base of the skull sawn through. The vessels and loose structures should be removed from the preparation, and the pharynx stuffed with tow or wool for the purpose of distend- ing it, and rendering the muscles more easy of dissection. The pha- rynx is invested by a proper pharyngeal fascia. The CoNSTRICTOR INFERIOR, the thickest of the three muscles of this class, arises from the upper rings of the trachea, the cricoid car- tilage, and the oblique line of the thyroid. Its fibres spread out and are inserted into the fibrous raphé of the middle of the pharynx, the inferior fibres being almost horizontal, and the —— oblique, and overlapping the middle constrictor. Relations.—By its eaternal surface with the anterior pee of the vertebral column, the longus colli, the sheath of the common carotid artery, the sterno-thyroid muscle, the thyroid gland, and some lymph- atic glands. By its internal surface with the middle constrictor, the stylo-pharyngeus, the palato-pharyngeus, and the mucous membrane of the pharynx. By its lower border, near the cricoid cartilage, it is in relation with the recurrent nerve; and by the upper border with the superior laryngeal nerve. The fibres of origin of this muscle are blended with those of the sterno-hyoid, sterno-thyroid, and crico- thyroid, and it frequently forms a tendinous arch across the latter. This muscle must be removed before the next can be examined. The ConsTRICTOR MEDIUS arises from the great cornu of the os hyoides, from the lesser cornu, and from the stylo-hyoidean ligament. It radiates from its origin upon the side of the pharynx, the lower fibres descending and being overlapped by the constrictor inferior, and the upper fibres ascending so as to cover in the constrictor supe- rior. It is éxserted into the raphé and by a fibrous aponeurosis into the basilar process of the occipital bone. Relations.—By its external surface with the vertebral column, the longus colli, rectus anticus major, the carotid vessels, inferior constric- tor, hyo-glossus muscle, lingual artery, pharyngeal plexus of nerves, and some lymphatic glands. By its internal surface, with the superior constrictor, stylo-pharyngeus, palato-pharyngeus, and mucous mem- brane of the pharynx. The upper portion of this muscle must be turned down, to bring the whole of the superior constrictor into view; in so doing, the stylo-pharyngeus muscle will be seen passing beneath its upper border. The ConsTRicToR SUPERIOR is a thin and quadrilateral plane of muscular fibres arising from the extremity of the molar ridge of the lower jaw, from the pterygo-maxillary ligament, and from the lower half of the internal pterygoid plate, and iserted into the raphé and basilar process of the occipital bone. Its superior fibres are arched and leave an interval between its upper border and the basilar process which is deficient in muscular fibres, and it is overlapped inferiorly by the middle constrictor. Between the side of the pharynx and the ramus of the lower jaw is a triangular interval, the maaillo pharyngeal 190 STYLO-PHARYNGEUS. space, which is bounded on the inner side by the superior constrictor muscle; on the outer side by the internal pterygoid muscle ; and behind by the rectus anticus major and vertebral column. In this space are situated the internal carotid artery, the internal jugular vein, and the glosso-pharyngeal, pneumogastric, spinal accessory, and hypo- glossal nerve. Relations.—By its eaternal surface with the vertebral column and its muscles, behind ; with the vessels and nerves contained in the maaz- illo-pharyngeal space laterally, the middle constrictor, stylo-pharyngeus, and tensor palati muscle. By its internal surface with the levator palati, palato-pharyngeus, tonsil, and mucous membrane of the pha- rynx, the pharyngeal fascia being interposed. The SryLo-PHARYNGEUS is a long and slender muscle arising from the inner side of the base of the styloid process ; it descends between the superior and middle con- strictor muscles,and spreads out beneath the mucous membrane of the pharynx, its inferior fibres being én- serted into the posterior bor- der of the thyroid cartilage. Relations.—By its eater- nal surface with the stylo- glossus muscle, external ca- rotid artery, parotid gland, and the middle constrictor. By its internal surface with the internal carotid artery, internal jugular vein, supe- rior constrictor, palato-pha- ryngeus, and mucous mem- brane. Along its lower bor- der is seen the glosso- pharyngeal nerve which crosses it, opposite the root of the tongue, to pass between the superior and middle constrictor and behind the hyo-glossus. The palato-pharyngeus is described with the muscles of the soft pa- Fig. 87.* * A side view of the muscles of the pharynx. 1. The trachea. 2. The cri- coid cartilage. 3. Thecrico-thyroid membrane. 4. The thyroid cartilage. 5. The thyro-hyoidean membrane. 6 The os hyoides. 7. The stylo-hyoidean ligament. 8. The esophagus. 9. The inferior constrictor. 10. The middle constrictor. 11. The superior constrictor. 12. The stylo-pharyngeus muscle passing down between the superior and middle constrictor. 13. The upper concave border of the superior constrictor; at this point the muscular fibres of the pharynx are deficient. 14. The pterygo-maxillary ligament. 15, The buccinator muscle. 16, The orbicularis oris, 17. The mylo-hyoideus, LEVATOR PALATI. 4191 late. It arises from the soft palate, and is imserted into the inner sur- face of the pharynx, and posterior border of the thyroid cartilage. Actions.—The three constrictor muscles are important agents in deglutition ; they contract upon the morsel of food as soon as it is received by the pharynx, and convey it downwards into the ceso- phagus. The stylo-pharyngei draw the pharynx upwards and widen it laterally. The palato-pharyngei also draw it upwards, and with the aid of the uvula close the opening of the fauces. Siath Group.— Muscles of the soft Palate. Levator palati, Tensor palati, Azygos uvule, Palato-glossus, Palato-pharyngeus. Dissection.—To examine these muscles, the pharynx must be opened from behind, and the mucous membrane carefully removed from off the posterior surface of the soft palate. The LEVATOR PALATI, a moderately thick muscle, arises Fig. 88.* from the extremity of the pe- trous bone and from the poste- rior and inferior aspect of the Eustachian tube, and passing down by the side of the poste- rior nares spreads out in the structure of the soft palate as far as the middle line. Relations. — Externally with the tensor palati and superior constrictor muscle; internally and posteriorly with the mucous membrane of the pharynx and soft palate; and by its lower border with the palatopharyn- geus. * The muscles of the soft palate. 1. A transverse section through the mid- dle of the base of the skull, dividing the basilar process of the occipital bone in the middle line, and the petrous portion of the temporal bone at each side. 2. The vomer covered by mucous membrane and separating the two posterior nares. 3,3. The Eustachian tubes. 4. The levator palati muscle of the left side ; the right has been removed. 5. The hamular process of the internal pterygoid plate of the left side, around which the aponeurosis of the tensor palati is seen turning. 6. The pterygo-maxillary ligament. 7. The superior constrictor muscle of the left side, turned aside. 8. The azygos uvulze muscle. g. The internal pterygoid plate. 10. The external pterygoid plate. 11. The tensor palati muscle. 12. Its aponeurosis expanding in the structure of the soft palate. 13. The external pterygoid muscle. 14, The attachments of two pairs of muscles cut short; the superior pair belong to the genio-hyo-glossi 192 PALATO-GLOSSUS.—PALATO-PHARYNGEUS. This muscle must be turned down from its origin on one side, and removed, and the superior constrictor dissected away from its ptery- goid origin, to bring the next muscle into view. The Tensor PALATI (circumflexus) is a slender and. flattened muscle; it arises from the scaphoid fossa at the base of the internal pterygoid plate and from the anterior aspect of the Eustachian tube. It descends to the hamular process around which it turns, and expands into a tendinous aponeurosis, which is izserted into the transverse ridge on the horizontal portion of the palate bone, and into the raphé. Reiations.— By its eaternal surface with the internal pterygoid muscle ; by its internal surface with the levator palati, internal ptery- goid plate, and superior constrictor. In the soft palate, its tendinous expansion is placed in front of the other muscles and in contact with the mucous membrane. The AzyGos UVUL& is not a single muscle, as might be inferred from its name, but a pair of small muscles placed side by side in the middle line of the soft palate. They arise from the spine of the palate bone, and are izserted into the uvula. By their anterior surface they are connected with the tendinous expansion of the levatores palati, and by the posterior with the mucous membrane. The two next muscles are brought into view throughout the whole of their extent, by raising the mucous membrane from off the pillars of the soft palate at each side. The PAaLaTo-GLossus (constrictor isthmi faucium) is a small fascicu- lus of fibres that arises in the soft palate, and descends to be inserted into the side of the fongue. It is the projection of this small muscle, covered by mucous membrane, that forms the anterior pillar of the soft palate. It has been named constrictor isthmi faucium from a function it performs in common with the palato-pharyngeus, viz. of constricting the opening of the fauces. The PALATO-PHARYNGEUS forms the posterior pillar of the fauces ; it arises by an expanded fasciculus from the lower part of the soft palate, where its fibres are continuous with those of the muscle of the opposite side; and is émserted into the posterior border of the thyroid cartilage. This muscle is broad above where it forms the whole thick- ness of the lower half of the soft palate, narrow in the posterior pillar, and again broad and thin in the pharynx where it spreads out pre- viously to its insertion. Relations—In the soft palate it is in relation with the mucous membrane both by its anterior and posterior surface ; above, with the muscular layer formed by the levator palati, and below with the mu- cous glands situated along the margin of the arch of the palate. In muscles ; the inferior pair, to the genio-hyoidei. 15. The attachment of the mylo-hyoideus of one side and part of the opposite. 16. The anterior attach- ments of the digastric museles. 17. The depression on the lower jaw corres- ponding with the submaxillary gland. The depression above the mylo-hyoideus, - thao the number 15 rests, corresponds with the situation of the sublingual gland. PRZVERTEBRAL MUSCLES. 193 the posterior pillar of the palate, it is surrounded for two-thirds of its extent by mucous membrane. In the pharynx, it is in relation by its outer surface with the superior and middle constrictor muscles, and by its inner surface with the mucous membrane of the pharynx, the pha- ryngeal fascia being interposed. Actions.—The azygos uvule shortens the uvula. The levator palati raises the soft palate, while the tensor spreads it out laterally so as to form a septum between the pharynx and posterior nares. Taking its fixed point from below the, tensor palati will dilate the Eustachian tube. The palato-glossus and pharyngeus constrict the opening of the fauces, and by drawing down the soft palate they serve to press the mass of food from the dorsum of the tongue into the pharynx. Seventh Group—Prevertebral Muscles. Rectus anticus major, Rectus anticus minor, Scalenus anticus, Scalenus posticus, Longus colli. Dissection.—These muscles have already been exposed by the removal of the face from the anterior aspect of the vertebral column ; all that is further needed is the removal of the fascia, by which they are invested. The Recrus ANTIcCUS MAJOR, broad and thick above, and narrow and pointed below, arises from the anterior tubercles of the transverse processes of the third, fourth, fifth, and sixth cervical vertebra, and is inserted into the basilar process of the occipital bone. Relations.—By its anterior surface with the pharynx, the internal carotid artery, internal jugular vein, superior cervical ganglion, sympa- thetic nerve, pneumogastric, and spinal accessory nerve. By its pos- terior surface with the longus colli, rectus anticus minor, and superior cervical vertebrae. The Recrus ANTICUS MINOR arises from the anterior border of the lateral mass of the atlas, and is imserted into the basilar process; its fibres being directed obliquely upwards and inwards. Relations.—By its anterior surface with the rectus anticus major, and externally with the superior cervical ganglion of the sympathetic. By its posterior surface with the articulation of the condyle of the oc- cipital bone with the atlas, and with the anterior occipito-atloid liga- ment. The ScaLENUS ANTICUs is a triangular muscle, as its name implies, situated at the root of the neck and appearing like a continuation of the rectus anticus major; it arises from the anterior tubercles of the transverse processes of the third, fourth, fifth, and sixth cervical ver- tebree, and is imserted into the tubercle upon the inner border of the first rib. Relations—By its anterior surface with the sterno-mastoid and ) 194 SCALENUS POSTICUS. omo-hyoid muscle, with the cervicalis superficialis and posterior sca- pular artery, with the phrenic nerve, and with the subclavian vein, by which it is separated from the subclavius muscle and clavicle. By its posterior surface with the nerves which go to form the brachial plexus, and below with the subclavian artery. By its inner side it is separated from the longus colli by the vertebral artery. Its relations with the subclavian artery and vein are very important, the vein being before and the artery behind the muscle.* The ScaLENUs pPosticus arises from the posterior tubercles of all the cervical vertebrae excepting the first. It is inserted by two fleshy fasciculi into the first and ; second ribs, The anterior Fig. 89.4 (scalenus medius) of the two fasciculi is large, and occupies all the surface of the first rib between the groove for the subclavian artery and the tuberosity. The posterior (scalenus pos- ticus) is small, and is at- tached to the second ‘rib. Albinus and Soemmering make five scaleni. Relations.—By its ante- rior surface with the bra- chial plexus and subclavian artery ; posteriorly with the levator anguli scapulee, cer- vicalis ascendens, transver- salis colli, and sacro-lum- balis ; internally with the first intercostal muscle, the first rib, the inter-trans- verse muscles, and cervical vertebree ; and externally with the sterno-mastoid, omo-hyoid, supra- scapular and posterior scapular ar- teries. * Ina subject dissected in the school of the Middlesex hospital during the winter of 1841 by Mr. Joseph Rogers, the subclavian artery of the left side was placed with the vein in front of the scalenus anticus muscle. + The preevertebral group of muscles of the neck. 1. The rectus anticus major muscle. 2. The scalenusanticus. 3. The lower part of the longus colli of the right side; it is concealed superiorly by the rectus anticus major. 4. The rectus anticus minor. 5. The upper portion of the longus colli muscle. _ 6. Its lower portion; the figure rests upon the seventh cervical vertebra. 7. The scalenus posticus. 8. The rectus lateralis of the left side. 9. One of the inter- transversales muscles. ‘ MUSCLES OF THE BACK, 195 The Loneus cout is a long and flat muscle, consisting of two por- tions. The wpper arises from the anterior tubercle of the atlas, and is inserted into the transverse processes of the third, fourth, and fifth cer- vical vertebrae. The lower portion arises from the bodies of the second and third, and transverse processes of the fourth and fifth, and passes down the neck, to be inserted into the bodies of the three lower cervi- cal and three upper dorsal vertebra. We should thus arrange these attachments in a tabular form :— Origin. Insertion. Upper 2? ‘Aven. 3d, 4th, and 5th transverse pro- . portion. § Saar cesses. Loves bad and third bodies 3 lower cervical vertebra, bo- ; 4th and 5th transverse dies. abies processes 3 upper dorsal, bodies. In general terms, the muscle is attached to the bodies and trans- verse processes of the five superior cervical vertebrze above, and to the bodies of the = three cervical and first three dorsal below. Relations.—By its anterior surface with the pharynx, esophagus, the sheath of the common carotid, internal jugular vein and pneumogastric - nerve, the sympathetic nerve, inferior laryngeal nerve, and inferior thyroid artery. By its posterior surface it rests upon the cervical and upper dorsal vertebree. Actions.—The rectus anticus major and minor preserve the equi- librium of the head upon the atlas; and, acting conjointly with the longus colli, flex and rotate the head and the cervical portion of the vertebral column. The scaleni muscles, taking their fixed point from below, are flexors of the vertebral column ; and, from above, elevators of the ribs, and therefore inspiratory muscles. Eighth Group.—Muscles of the Larynx. These muscles are described with the anatomy of the larynx, in Chapter X. MUSCLES OF THE TRUNK. The muscles of the trunk may be subdivided into four natural groups; viz. 1. Muscles of the back. 2. Muscles of the thorax. 3. Muscles of the abdomen. 4, Muscles of the perineum. 1, Muscles of the back.—The region of the back, in consequence of its extent, is common to the neck, the upper extremities, and the 196 MUSCLES OF THE BACK. abdomen. The muscles of which it is composed are numerous, and may be arranged into six layers. First Layer. Trapezius, Latissimus dorsi. Second Layer. Levator anguli scapulz, Rhomboideus minor, Rhomboideus major. Third Layer. Serratus posticus superior, Serratus posticus inferior, Splenius capitis, Splenius colli. Fourth Layer. (Dorsal Group.) Sacro-lumbalis, Longissimus dorsi, Spinalis dorsi. (Cervical Group.) Cervicalis ascendens, Transv ersalis. colli, % 7 ) i Complexus. Fifth Layer. (Dorsal Group.) Semi-spinalis dorsi, Semi-spinalis colli. (Cervical Group.) Rectus anticus major, Rectus anticus minor, Rectus lateralis, Obliquus inferior, Obliquus superior. Siath Layer. Multifidus spine, Levatores costarum, Supra-spinalis, Inter-spinales, Inter-transversales. First Layer. Dissection —The muscles of this layer are to be dissected by making an incision along the middle line of the back, from the tubercle on the occipital bone to the coccyx. From the upper point of this incision carry a second along the side of the neck, to the middle of the clavicle. Inferiorly, an incision must be made from the extremity of the sacrum, along the crest of the ilium, to about its middle. For convenience of dissection, a fourth may be carried from the middle of the spine to the acromion process. ‘The integument and superficial fascia, together, are to be dissected off the muscles, in the course of their fibres, over the whole of this region. The Trapezius muscle (trapezium, a quadrangle with unequal sides) arises from the superior curved line of the occipital bone, from the ligamentum nuchz, supra-spinous ligament, and spinous processes of the last cervical and all the dorsal vertebra. The fibres converge from these various points, and are inserted into the scapular third of the clavicle, the acromion process, and the whole length of the upper border of the spine of the scapula. The inferior fibres become tendin- ous near the scapula, and glide over the triangular surface at the posterior extremity of its spine, upon a bursa mucosa. When the trapezius is dissected on both sides, the two muscles resemble a tra- ees eee aie ee ee! ee” LATISSIMUS DORSI. 197 pezium, or diamond-shaped quadrangle, on the posterior part of the shoulders: hence the muscle was formerly named cucullaris (cucullus, a monk’s cowl). The cervical and upper part of the dorsal portion of the muscle is tendinous at its origin, and forms, with the muscle of the opposite side, a kind of tendinous ellipse. Relations—By its superficial surface with the integument and superficial fascia, to which it is closely adherent by its cervical por- tion, loosely by its dorsal portion. By its deep surface, from above downwards, with the complexus, splenius, levator anguli scapule, supra-spinatus, a small portion of the serratus posticus superior, rhom- boideus minor, rhomboideus major, intervertebral aponeurosis which separates it from the erector spinze, and with the latissimus dorsi. The anterior border of the cervical portion of this muscle forms the poste- rior boundary of the posterior triangle of the neck. The clavicular insertion of the muscle sometimes advances to the middle of the cla- vicle, or as far as the outer border of the sterno-mastoid, and occa- sionally it has been seen to overlap the latter. This is a point of much importance to be borne in mind in the operation for ligature of the subclavian artery. The spinal accessory nerve passes beneath the anterior border, near to the clavicle, previously to its distribution to the muscle. The ligamentum nuche is a thin cellulo-fibrous layer extended from - the tubercle and spine of the occipital bone, to the spinous process of the seventh cervical vertebra, where it is continuous with the supra- spinous ligament. It is connected with the spinous processes of the rest of the cervical vertebrae, with the exception of the atlas, by means of a small fi slip which is sent off by each. It is the analogue of an important elastic ligament in animals. The LaTissimus DoRSI muscle covers the whole of the lower part of the back and loins. It arises from the spinous processes of the six inferior dorsal vertebrae, from all the lumbar and sacral spinous pro- cesses, from the posterior third of the crest of the ilium, and from the three lower ribs ; the latter origin takes place by muscular slips, which indigitate with the external oblique muscle of the abdomen. The fibres from this extensive origin converge as they ascend, and cross the inferior angle of the scapula; they then curve around the lower bor- der of the teres major muscle, and terminate in a short quadrilateral tendon,* which lies in front of the tendon of the teres, and is inserted into the bicipital groove. A synovial bursa is interposed between the muscle and the lower angle of the scapula, and another between its tendon and that of the teres major. The muscle frequently receives a small fasciculus from the scapula as it crosses its inferior angle. Relations. — By its superficial surfuce with the integument and superficial fascia; the latter is very dense and fibrous in the lumbar region; and with the trapezius. By its deep surface, from below up- * A small muscular fasciculus from the pectoralis major is sometimes found connected with this tendon. 198 MUSCLES OF THE BACK. * The first and second and part of the third layer of muscles of the back; the first layer being shewn upon the right, and the second on the left side. 1. The trapezius muscle. 2. The tendinous portion which, with a corresponding por- tion in the opposite muscle, forms the tendinous ellipse on the back of the neck. 3. The acromion process and spine of the scapula. 4. The latissimus dorsi muscle. 5. The deltoid. 6. The muscles of the dorsum of the scapula, infra- spinatus, teres minor, and teres major. 7. The external oblique muscle. 8. The gluteus medius. 9. The glutei maximi. 10. The levator anguli scapule. 11. The rhomboideus minor. 12. The rhomboideus major. 13. The splenius capitis ; the muscle immediately above, and overlaid by the splenius, is the complexus, 14. The splenius colli, only partially seen; the common origin of RHOMBOIDEIL. 199 wards, with the erector spine, serratus posticus inferior, intercostal muscles and ribs, rhomboideus major, inferior angle of the scapula and teres major. The latissimus dorsi, with the teres major, forms the posterior border of the axilla. Second Layer. Dissection —This layer is brought into view by dividing the two preceding muscles near their insertion, and turning them to the op- posite side. The LEVATOR ANGULI SCAPULZ arises by distinct slips, from the posterior tubercles of the transverse processes of the four upper cer- vical vertebrae, and is inserted into the upper angle and posterior bor- der of the scapula, as far as the triangular smooth surface at the root of its spine. Relations.—By its superficial surface with the trapezius, sterno- mastoid, and integument. By its deep surface with the splenius colli, transversalis colli, cervicalis ascendens, scalenus posticus, and serratus posticus superior. The tendons of origin are interposed between the eS ay of the scalenus posticus in front and the splenius colli behind. The RuomBomEUS MINOR (rhombus, a parallelogram with four equal sides) is a narrow slip of muscle, detached from the rhomboideus major by a slight cellular interspace. It arises from the spinous pro- cess of the last cervical vertebra and ligamentum nuche, and is in- serted into the edge of the triangular surface, on the posterior border of the scapula. The RuomBoIpEUS MAJOR arises from the spinous processes of the four upper dorsal vertebrae and from the inter-spinous ligaments; it is inserted into the posterior border of the scapula as far as its inferior angle. The upper and middle portion of the insertion is effected by means of a tendinous band which is attached in a longitudinal direc- tion to the posterior border of the scapula. Relations.—By their superficial surface the two rhomboid muscles are in relation with the trapezius, and the rhomboideus major with the latissimus dorsi and integument. By their deep surface they cover in the serratus posticus superior, part of the erector spine, the intercostal muscles and ribs. the splenius is seen attached to the spinous processes below the lower border of the rhomboideus major. 15. The vertebral aponeurosis. 16. The serratus posticus inferior. 17. The supra-spinatus muscle. 18. The infra-spinatus. 19. The teres minor muscle. 20. The teres major. 21. The long head of the triceps, passing between the teres minor and major to the upper arm. 22. The serratus magnus, proceeding forwards from its origin at the base of the sca- pula. 23. The internal oblique muscle. 200 MUSCLES OF THE BACK. Third Layer. Dissection—The third layer consists of muscles which arise from the spinous processes of the vertebral column, and pass outwards. It is brought into view by dividing the levator anguli scapulz near its insertion, and reflecting the two rhomboid muscles upwards from their insertion into the scapula. The latter muscles should now be removed. The SERRATUS POSTICUS SUPERIOR is situated at the upper part of the thorax; it arises from the ligamentum nuchz, the spinous process of the last cervical and those of the two upper dorsal vertebre. The muscle passes obliquely downwards and outwards, and is inserted by four serrations into the upper border of the second, third, fourth, and fifth ribs. Relations —By its superficial surface with the trapezius, rhom- boideus major and minor, and serratus magnus. By its deep surface with the splenius, the upper part of the erector spinze, the intercostal muscles and ribs. The SERRATUS POSTICUS INFERIOR arises from the spinous pro- cesses and interspinous ligaments of the two last dorsal and two upper lumbar vertebrae, and passing obliquely upwards is inserted by four serrations into the lower border of the four lower ribs. Both muscles are constituted by a thin aponeurosis for about half their extent. Relations. —By its superficial surface with the latissimus dorsi, its tendinous origin being inseparably connected with the aponeurosis of that muscle. By its deep surface with the aponeurosis of the obliquus internus, with which it is also closely adherent; with the erector spine, the intercostal muscles and lower ribs. The upper border is continuous with a thin tendinous layer, the vertebral aponeurosis. The Vertebral aponeurosis is a thin membranous expansion composed of longitudinal and transverse fibres, and extending the whole length of the thoracic region. It is attached mesially to the spinous pro- cesses of the dorsal vertebrae, and externally to the angles of the ribs ; superiorly it is continued upwards beneath the serratus posticus supe- rior, with the lower border of which it is sometimes connected. It serves to bind down the erector spine, and separate it from the super- ficial muscles, The serratus posticus superior must be removed from its origin and turned outwards, to bring into view the whole extent of the splenius muscle, The SPLENIUS MUSCLE is single at its origin, but divides soon after into two portions, which are destined to distinct insertions. It arises from the lower half of the ligamentum nuchz, from the spinous pro- cess of the last cervical, and from the spinous processes and interspinous ligaments of the six upper dorsal vertebra ; it divides as it ascends the neck into the splenius capitis and colli. The splenius capitis is in- serted into the rough surface of the occipital bone between the two curved lines, and into the mastoid portion of the temporal bone. FOURTH LAYER. 201 The splenius colli is inserted into the posterior tubercles of the transverse processes of the three or four upper cervical vertebre. Relations.—By its superficial surface with the trapezius, sterno- mastoid, levator anguli scapule, rhomboideus minor and major, and serratus posticus superior. By its deep surface with the spinalis dorsi, longissimus dorsi, semi-spinalis colli, complexus, trachelo-mastoid, and transversalis colli. The tendons of insertion of the splenius colli are interposed between the insertions of the levator anguli scapule in front, and the transversalis colli behind. The splenii of opposite sides of the neck leave between them a trian- gular interval, in which the complexus is seen. Fourth Layer. Dissection.—The two serrati and two splenii muscles must be re- moved by cutting them away from their origins and insertions, to bring the fourth layer into view. Three of these muscles, viz. sacro-lumbalis, longissimus dorsi, and spinalis dorsi, are associated under the name of erector spine. They occupy the lumbar and dorsal portion of the back. The remaining four are situated in the cervical region. The SacrRo-LUMBALIS and LONGISSIMUS DORSI arise by a common origin from the posterior third of the crest of the ilium, from the pos- terior surface of the sacrum, and from the lumbar vertebra: opposite the last rib a line of separation begins to be perceptible between the two muscles. The sacro-lumbalis is inserted by separate tendons into the angles of the six lower ribs. On turning the muscle a little out- wards, a number of tendinous slips will be seen taking their origin from the ribs, and terminating in a muscular fasciculus, by which the sacro-lumbalis is prolonged to the upper part of the thorax. This is the musculus accessorius ad sacro-lumbalem : it arises from the angles of the six lower ribs, and is énserted by separate tendons into the angles of the six upper ribs. The longissimus dorsi is inserted into all the ribs, between their tubercles and angles. The SPINALIS DoRSI arises from the spinous processes of the two upper lumbar and two lower dorsal vertebrae, and is inserted into the spinous processes of all the upper dorsal vertebra; the two muscles form an ellipse, which appears to enclose the spinous processes of all the dorsal vertebree. Relations.—The erector spinz muscle is in relation by its super- ficial surface (in the lumbar region) with the conjoined aponeurosis of the transversalis and internal oblique muscle, which separates it from the aponeurosis of the serratus posticus inferior, and longissimus dorsi; (in the dorsal region) with the vertebral aponeurosis, which separates it from the latissimus dorsi, trapezius, and serratus posticus superior, and with the splenius. By its deep surface (in the lumbar 202 MUSCLES OF THE BACK. — = — oe i \; it At \ tt = — as a & => =x region) with the multifidus spine, transverse processes of the lumbar vertebrae, and with the middle layer of the aponeurosis of the trans- * The fourth and fifth, and part of the sixth layer of the muscles of the back. 1. The common origin of the erector spinzee muscle. 2. The sacro-lumbalis. 3. The longissimus dorsi. 4. The spinalis dorsi. 5. The cervicalis ascendens. 6. The transversalis colli. 7. The trachelo-mastoideus. 8. The complexus. 9. The transversalis colli, shewing its origin. 10, The semispinalis dorsi. 11. The semispinalis colli, 12. The rectus posticus minor. 13. The rectus posti- cus major. 14. The obliquus superior. 15. The obliquus inferior. 16. The multifidus spine. 17. The levatores costarum. 18. Intertransversales. 19. The quadratus lumborum. FOURTH LAYER. 203 versalis abdominis, which separates it from the quadratus lumborum ; (in the dorsal region) with the multifidus spine, semi-spinalis dorsi, levatores costarum, intercostal muscles, and ribs as far as their angles. Internally or mesially with the multifidus spine, and semi-spinalis dorsi, which separate it from the spinous processes and arches of the vertebre. The two layers of aponeurosis of the transversalis abdominis, toge- ther with the spinal column in the lumbar region, and the vertebral aponeurosis with the ribs and spinal column in the dorsal region, form a complete osseo-aponeurotic sheath for the erector spinze. The CERVICALIS aASCENDENS is the continuation of the sacro-lumbalis upwards into the neck. It arises from the angles of the four upper ribs, and is inserted by slender tendons into the posterior tubercles of the transverse processes of the four lower cervical vertebra. Relations.—By its superficial surface with the levator anguli sca- pulz; by its deep surface with the upper intercostal muscles and ribs, and with the intertransverse muscles; externally with the scalenus posticus; and internally with the transversalis colli. The tendons of insertion are interposed between the attachments of the scalenus pos- ticus and transversalis colli. The TRANSVERSALIS COLLI would appear to be the continuation upwards into the neck of the longissimus dorsi; it arises from the ‘transverse processes of the third, fourth, fifth, and sixth dorsal verte- bre, and is inserted into the posterior tubercles of the transverse pro- cesses of the four or five inferior cervical vertebree. Relations. — By its superficial surface with the levator anguli sca- pulz, splenius and longissimus dorsi. By its deep surface with the complexus, trachelo-mastoideus and vertebree; eaternally with the musculus accessorius ad sacro-lumbalem, and cervicalis ascendens ; internally with the trachelo-mastoideus and complexus. The tendons of insertion of this muscle are interposed between the tendons of inser- tion of the cervicalis ascendens on the outer side, and of origin of the trachelo-mastoid on the inner side. The TrRacHELo-mastorp is likewise a continuation upwards from the longissimus dorsi. It is a very slender and delicate muscle, arising from the transverse processes of the four upper dorsal and four lower cervical vertebrae, and inserted into the mastoid process to the inner side of the digastric fossa. Relations.—The same as those of the preceding muscle, excepting that it is interposed between the transversalis colli and the complexus. Its tendons of attachment are the most posterior of those which are connected with the posterior tubercles of the transverse processes of the cervical vertebre. The Compiexvs is a large muscle, and with the splenius forms the great bulk of the back of the neck. It crosses the direction of the splenius, arising from the transverse processes of the four upper dor- sal, and from the transverse and articular processes of the four lower cervical vertebree, and is inserted into the rough surface on the occipital 204 MUSCLES OF THE BACK. bone between the two curved lines, near the occipital spine. A large fasciculus of the complexus is so distinct from the principal mass of the muscle as to have led to its description as a separate muscle under the name of biventer cervicis. This appellation is not inappropriate for the muscle consists of a central tendon, with two fleshy bellies. The complexus is crossed in the upper part of the neck by a tendinous intersection. Relations. —By its superficial surface with the trapezius, splenius, trachelo-mastoid, transversalis colli, and longissimus dorsi. By its deep surface with the semi-spinalis dorsi and colli, the recti and obliqui. It is separated from its fellow of the opposite side by the ligamentum nuchz, and from the semi-spinalis colli by the profunda cervicis artery and princeps cervicis branch of the occipital, and by the posterior cer- vical plexus of nerves. Fifth Layer. Dissection.—The muscles of the preceding layer are to be removed by dividing them transversely through the middle, and turning one extremity upwards, the other downwards. In this way the whole of the muscles of the fourth layer may be got rid of, and the remaining muscles of the spine brought into a state to be examined. The SEMI-SPINALES MUSCLES are connected with the transverse and spinous processes of the vertebrae, spanning one-half of the verte- bral column ; hence their name semi-spinales. The SEMI-SPINALIS DORSI arises from the transverse processes of the six lower dorsal vertebra, and is inserted into the spinous pro- cesses of the four upper dorsal, and two lower cervical vertebree. The SEMI-SPINALIS COLLI arises from the transverse processes of the four upper dorsal vertebrae, and is inserted into the spinous pro- cesses of the four upper cervical vertebrae, commencing with the axis. Relations.—By their superficial surface the semi-spinales are in rela- tion from below upwards with the spinalis dorsi, longissimus dorsi, com- plexus, splenius, with the profunda cervicis and princeps cervicis artery, and posterior cervical plexus of nerves. By their deep surface with the multifidus spinze muscle. Occipital Group.—This group of small muscles is intended for the varied movements of the cranium on the atlas, and the atlas on the axis. They are extremely pretty in appearance. The Recrus posticus MAJoR arises from the spinous process of = axis, and is inserted into the inferior curved line of the occipital one. The Recrus Pposticus MINoR arises from the spinous tubercle of the atlas, and is inserted into the rough surface on the occipital bone, beneath the inferior curved line. The RecTus LATERALIS is extended between the transverse pro- cess of the atlas and the occipital bone ; it arises from the transverse SIXTH LAYER. © 205 process of the atlas, and is inserted into the rough surface of the occi- pital bone, external to the condyle. The OBLIQUUS INFERIOR arises from the spinous process of the axis, and passes obliquely outwards to be inserted into the extremity of the transverse process of the atlas. The OBLIQUUS SUPERIOR arises from the extremity of the trans- verse process of the atlas, and passes obliquely inwards to be inserted into the rough surface of the occipital bone, between the curved lines. : Relations.—By their superficial surface the recti and obliqui are in relation with a strong aponeurosis which separates them from the com- plexus. By their deep surface with the atlas and axis, and their arti- culations. The rectus posticus major partly covers in the rectus minor. The rectus lateralis is in relation by its anterior surface with the internal jugular vein, and by its posterior surface with the vertebral artery. Siath Layer. Dissection.—The semi-spinales muscles must both be removed to obtain a good view of the multifidus spine which lies beneath them, and fills up the concavity between the spinous and transverse processes, the whole length of the vertebral column. The MuLtTIFIDUS sPIN& consists of a great number of fleshy fasci- culi extending between the transverse and spinous processes of the vertebree, from the sacrum to the axis. Each fasciculus arises from a transverse process, and is inserted into the spinous process of the first or second vertebra above. Some deep fasciculi of the multifidus spine have recently been described by Professor Theile under the name of rotatores spine. Relations.—By its superficial surface with the longissimus dorsi, semi-spinalis dorsi, and semi-spinalis colli. By its deep surface with the arches and spinous processes of the vertebral column, and in the cervical region with the ligamentum nuche. The LEVATORES COSTARUM, twelve in number on each side, arise from the transverse processes of the dorsal vertebrae, and pass ob- liquely outwards and downwards to be inserted into the rough surface between the tubercle and angle of the rib below them. The first of these muscles arises from the transverse process of the last cervical vertebra, and the last from that of the eleventh dorsal. The levatores of the inferior ribs, besides the distribution here described send a fasciculus downwards to the second rib below their origin, and conse- quently are inserted into two ribs. Relations.—By their superficial surface with the longissimus dorsi and sacro-lumbalis. By their deep surface with the intercostal muscles and ribs. The Supra-sPINALIs is a’small and irregular muscle lying upon the spinous processes in the cervical region and composed of several fasciculi. The fasciculi arise from the inferior cervical and superior 206 MUSCLES OF THE BACK. . dorsal vertebrae, and are zzserted into the spinous process of the axis. From its analogy to the spinalis dorsi this muscle has been named spinalis colli, It is sometimes wanting. The INTERSPINALES are small muscular slips arranged in pairs and situated between the spinous processes of the vertebrae. In the cer- vical region there are six pairs of these muscles, the first being placed between the axis and third vertebra, and the sixth between the last cervical and first dorsal. In the dorsal region, rudiments of these muscles are occasionally met with between the upper and lower verte- bree, but are absent in the rest. In the /wmbar region there are six pairs of interspinales, the first pair occupying the interspinous space between the last dorsal and first lumbar vertebra, and the last the space between the fifth lumbar and sacrum. They are thin and imperfectly developed. Rudimentary interspinales are occasionally met with between the lower part of the sacrum and the coccyx; these are the analogues of the caudal muscles of brutes; in man they have been named collectively the eatensor coccygis. The INrTERTRANSVERSALES are small quadrilateral muscles situated between the transverse processes of the vertebre. In the cervical region they are arranged in pairs corresponding with the double con- formation of the transverse processes, the vertebral artery and anterior division of the cervical nerves lying between them. The rectus an- ticus minor and rectus lateralis represent the intertransversales be- tween the atlas and cranium. In the dorsal region the anterior inter- transversales are represented by the intercostal muscles, while the pos-. terior are mere tendinous bands, muscular only between the first and last vertebrae. In the lumbar region, the anterior intertransyersales are thin and occupy only part of the space between the transverse processes. Analogues of posterior intertransversales exist in the form of small muscular fasciculi (interobliqui) extended between the rudi- mentary posterior transverse processes of the lumbar vertebra. With regard to the origin and insertion of the muscles of the back, the student should be informed, that no regularity attends their at- tachments. At the best, a knowledge of their exact connections, even were it possible to retain it, would be but a barren information, if not absolutely injurious, as tending to exclude more valuable learning. I have therefore endeavoured to arrange a plan, by which they may be more easily recollected, by placing them in a tabular form (p. 208), that the student may see, at a single glance, the origin and insertion of each, and compare the natural grouping and similarity of attach- ments of the various layers. In this manner also their actions will be better comprehended, and learnt with greater facility. Actions. — The upper fibres of the trapezius draw the shoulder upwards and backwards ; the middle fibres, directly backwards ; and the lower, downwards and backwards, The lower fibres also act by producing rotation of the scapula upon the chest. If the shoulder be fixed the upper fibres will flex the spine towards the corresponding side, The latissimus dorsi is a muscle of the arm, drawing it back- SIXTH LAYER. 207 wards and downwards, and at the same time rotating it inwards ; if the arm be fixed, the latissimus dorsi will draw the spine to that side, and, raising the lower ribs, be an inspiratory muscle ; and if both arms be fixed, the two muscles will draw the whole trunk forwards, as in climbing or walking on crutches. The levator anguli scapulz lifts the upper angle of the scapula, and with it the entire shoulder, and the rhomboidei carry the scapula and shoulder upwards and backwards. ' In examining the following table, the student will observe the constant recurrence of the number four in the origin and insertion of the muscles. Sometimes the four occurs at the top or bottom of a region of the spine, and frequently includes a part of two regions, and takes two from each, as in the case of the serrati. Again, he will perceive that the muscles of the upper half of the table take their origin from spinous processes, and pass outwards to transverse, whereas the lower half arise mostly from transverse processes. To the student, then, we commit these reflections, and leave it to the peculiar tenor of his own mind to make such arrangements as will be best retained by his memory. The serrati are respiratory muscles acting in opposition to each other, the serratus posticus superior drawing the ribs upwards, and thereby expanding the chest; and the inferior drawing the lower ribs downwards and diminishing the cavity of the chest. The former is an inspiratory, the latter an expiratory muscle. The splenii muscles of one side draw the vertebral column backwards and to one side, and rotate the head towards the corresponding shoulder. The muscles of opposite sides, acting together, will draw the head directly backwards. They are the natural antagonists of the sterno-mastoid muscles. The sacro-lumbalis with its accessory muscle, the longissimus dorsi and spinalis dorsi, are known by the general term of erectores spine, which sufficiently expresses their action. They keep the spine sup- ported in the vertical position by their broad origin from below, and by means of their insertion, by distinct tendons, into the ribs and spinous processes. Being made up of a number of distinct fasciculi, which alternate in their actions, the spine is kept erect without fatigue, even when they have to counterbalance a corpulent abdominal development. The continuations upwards of these muscles into the neck preserve the steadiness and uprightness of that region. When the muscles of one side act alone, the neck is rotated upon its axis. The compleaus, by being attached to the occipital bone, draws the head backwards, and counteracts the muscles on the anterior part of the neck. It assists also in the rotation of the head. The semi-spinales and multifidus spine muscles act directly on the vertebrae, and contribute to the general action of supporting the verte- bral column erect. The four little muscles situated between the occiput and the two first vertebra, effect the various movements between these bones; the recti producing the antero-posterior actions, and the obliqui the rotatory motions of the atlas on the axis. 208 TABLE OF ORIGIN AND INSERTION a lig. nuche, ORIGIN. Te Spinous Transverse : ee . Layers. Processes. Pitweneed: Ribs. Additional. lst Layer. oli a n ast cervic occipital bone anc Trapezius . oP) 12 pe ' - A 4 ; ligamentum nucha Latissimus dorsi. ; 6 a ree t . 3 lower . |sacrum and ilium > 2nd Layer. Levator anguli ‘ ‘ scapulse t , . | 4 upper cervical ‘ Rhomboideus min. Rhomboideus major 3rd Layer. Serratus posticus superior . Serratus posticus inferior Splenius — Splenius colli ‘ 4th Layer. Sacro-lumbalis —— accessorius ad t sacro-lumbalem . Longissimus dorsi . z Cervicalis ascendens Spinalis dorsi Transversalis colli . Trachelo-mastoideus Complexus . 5th Layer. Semi-spinalis dorsi Semi-spinalis colli . Rectus posticus maj. Rectus posticus min. Rectus lateralis Obliquus inferior “Obliquus superior . 6th Layer. Multifidus spine . Levatores costarum Supra spinalis Inter-spinalis Inter-transversales . last cervical 4 upper dorsal lig. nuchee, last cervical, 2 upper dorsal 2 lower dorsal, 2 upper lumbar lig. nuchee, last cervical, 6 upper dorsal 2 lower dorsal, 2 upper lumbar . . . . PLA DA Ne j 3rd, 4th, 5th, and 6th dorsal 4 upper dorsal, ero dorsal, 4 . |6 lower dorsal Na .4 lower cervical —s On ee eee . . . ower cervical angles of 4 upper : 4 upper dorsal . 3 axis > atlas : ‘ . - | atlas axis ; 2 5 from sacrum to ; c 3rd cervical , / 5 last cervical and ; : eleven dorsal : cervical . ; ; : ‘ cervical &lumbar| . . ; ‘ . - | cervical & lumbar sacrum and lum vertebrze 7 pee ie dl OF THE MUSCLES OF THE BACK. 209 e INSERTION. Spinous Processes. ameter ies ren Ribs. Additional. 5 clavicle and spine of , r Z the scapula. ) | posterior bicipital : é ‘ 5 } ridge of the humerus. ; { angle and base of the . scap s . | base of the scapula. : - | base of the scapula. 2nd, 3rd, 4th, and 5th. ° 4 lower ribs. occipital and mastoid 4 upper cervical | . . ° rtion of temporal, ne. angles of 6 lower. ; angles of 6 upper. 5 allthe ribs between the | 4 : tubercles and angles. } upper dorsal. . . ) 4 lower cervical. 4 lower cervical. a - : : - | mastoid process. : j occipital bone between , ? the curved lines. 4 upper dorsal, 2 lower cervical. 4 upper cervical, a except atlas. : : : : occipital bone. : . . occipital bone. ‘ . ; occipital bone. atlas. ; ‘ : occipital bone. cervical & lumbar. all the ribs between the tubercles and angles. | il 210 MUSCLES OF THE THORAX. The actions of the remaining muscles of the spine, the supra and inter-spinales and inter-transversales, are expressed in their names. _ They approximate their attachments and assist the more powerful muscles in preserving the erect position of the body. The levatores costarum raise the posterior parts of the ribs, and are probably more serviceable in preserving the articulation of the ribs from dislocation, than in raising them in inspiration. MUSCLES OF THE THORAX. The principal muscles situated upon the thorax belong in their actions to the upper extremity, with which they will be described. They are the pectoralis major and minor, subclayius and serratus magnus. The true thoracic muscles are few in number, and appertain exclusively to the actions of the ribs; they are, the— Intercostales externi, Intercostales interni, Triangularis sterni. The intercostal muscles are two planes of muscular and tendinous fibres directed obliquely between the adjacent ribs and closing the in- tercostal spaces. They are seen partially upon the removal of the pec- toral muscles, or upon the inner surface of the chest. The triangularis sterni is within the chest, and requires the removal of the anterior part of the thorax to bring it into view. The INTERCOSTALES EXTERNI, eleven on each side, commence pos- teriorly at the tubercles of the ribs, and advance forwards to the cos- tal cartilages where they terminate in a thin aponeurosis which is con- tinued onwards to the sternum. Their fibres are directed obliquely downwards and inwards, pursuing the same line with those of the ex- ternal oblique muscle of the abdomen. They are thicker than the in- ternal intercostals. The INTERCOSTALES INTERNI, also eleven on each side, commence anteriorly at the sternum, and extend backwards as far as the angles of the ribs, whence they are prolonged to the vertebral column by a thin aponeurosis. Their fibres are directed obliquely downwards and backwards, and correspond in direction with those of the internal ob- lique muscle of the abdomen. The two muscles cross each other in the direction of their fibres. In structure the intercostal muscles consist of an admixture of muscular and tendinous fibres. They arise from the two lips of the lower border of the ribs, the external from the outer lip, the internal from the inner, and are inserted into the upper border. Relations. — The external intercostals, by their external surface, with the muscles which immediately invest the chest, viz. the pecto- ralis major and minor, the serratus magnus, serratus posticus superior Se — MUSCLES OF THE ABDOMEN. 211 and inferior, scalenus posticus; sacro-lumbalis, and longissimus dorsi, with their continuations, the cervicalis ascendens and transversalis colli; the levatores costarum, and the obliquus externus abdominis. By their internal surface with the internal intercostals, the intercostal vessels and nerves, and a thin aponeurosis, and posteriorly with the pleura. The internal intercostals, by their eaternal surface with the external intercostals, and intercostal vessels and nerves; by their ix- ternal surface with the pleura costalis, the triangularis sterni and diaphragm. Connected with the internal intercostals are a variable number of muscular fasciculi which pass from the inner surface of one rib near its middle to the next or next but one below; these are the subcostal or more correctly the ixtracostal muscles. The TRIANGULARIS STERNI, situated upon the inner wall of the front of the chest, arises by a thin aponeurosis from the side of the sternum, ensiform cartilage, and sternal extremities of the costal car- tilages; and is inserted by fleshy digitations into the cartilages of the third, fourth, fifth, and sixth ribs, and often into that of the second, Relations.—By its eaternal surface with the sternum, the ensiform cartilage, the costal cartilages, internal intercostal muscles, and in- ternal mammary vessels. By its internal surface with the pleura costalis, the areolar tissue of the anterior mediastinum and the diaphragm. The lower fibres of the triangularis sterni are continuous with those of the diaphragm. Actions.—The intercostal muscles raise the ribs when they act from above, and depress them when they take their fixed point from below. They are, therefore, both inspiratory and expiratory muscles. The triangularis sterni draws down the costal cartilages, and is therefore an expiratory muscle. MUSCLES OF THE ABDOMEN. The muscles of this region are, the— Obliquus externus (descendens), Obliquus internus (ascendens), Cremaster, Transversalis, Rectus, Pyramidalis, Quadratus lumborum, Psoas parvus, Diaphragm. Dissection.—The dissection of the abdominal muscles is to be com- menced by making three ineisions:—The first, vertical, in the middle 212 MUSCLES OF THE ABDOMEN. line, from over the lower part of the sternum to the pubes; the second, oblique, from the umbilicus, upwards and outwards, to the outer side of the chest, as high as the fifth or sixth rib; and the third, oblique, from the umbilicus, downwards and outwards, to the middle of the crest of the ilium. The three flaps included by these incisions should then be dissected back in the direction of the fibres of the ex- ternal oblique muscle, beginning at the angle of each. The integu- ment and superficial fascia should be dissected off together so as to ex- pose the fibres of the muscle at once. If the external oblique muscle be dissected on both sides, a white tendinous line will be seen along the middle of the abdomen, extend- ing from the ensiform cartilage to the os pubis; this is the linea alba. A little external to it, on each side, two curved lines will be observed extending from the sides of the chest to the os pubis, and bounding the recti muscles: these are the linee semilunares. Some transverse lines, linee transverse, three or four in number, connect the lines semilunares with the linea alba. The EXTERNAL OBLIQUE MUSCLE (obliquus eaternus abdominis descendens) is the external flat muscle of the abdomen. Its name is derived from the obliquity of its direction, and the descending course of its fibres. It arises by fleshy digitations from the external surface of the eight inferior ribs; the five upper digitations being received be- tween corresponding processes of the serratus magnus, and the three lower of the latissimus dorsi. Soon after its origin it spreads out into a broad aponeurosis, which is inserted into the outer lip of the crest of the ilium for one half its length, the anterior superior spinous process of the ilium, spine of the os pubis, pectineal line, front of the os pubis, and linea alba. . The lower border of the aponeurosis, which is stretched between the anterior superior spinous process of the ilium and the spine of the os pubis, is rounded from being folded inwards, and forms Poupart’s ligament; the insertion into the pectineal line is Gimbernat’s ligament. Just above the crest of the os pubis is the eaternal abdominal ring, a triangular opening formed by the separation of the fibres of the apo- neurosis of the external oblique. It is oblique in its direction, and corresponds with the course of the fibres of the aponeurosis. It is bounded below by the crest of the os pubis; on either side, by the borders of the aponeurosis, which are called pillars; and above by some curved fibres (inter-columnar), which originate from Poupart’s ligament, and cross the upper angle of the ring, soas to give it strength. The eaternal pillar, which is at the same time inferior from the ‘obliquity of the opening, is inserted into the spine of the os pubis; the internal or supe- rior pillar forms an interlacement with its fellow of the opposite side over the front of the symphysis pubis. The external abdominal ring gives passage to the spermatic cord in the male, and round ligament in the female: they are both invested in their passage through it by a thin fascia derived from the edges of the ring, and called inter-columnar JSascia, or fascia spermatica. ie obi es + Nore OBLIQUUS INTERNUS ABDOMINIS. 213 "The pouch of inguinal hernia, in passing through this opening, re- ceives the inter-columnar fascia, as one of its coverings. Relations —By its eaternal surface with the superficial fascia and integument, and with the cutaneous vessels and nerves, particularly the superficial epigastric and superficial circumflexa ilii vessels. It is ge- nerally overlapped posteriorly by the latissimus dorsi. By its internal surface with the internal oblique, the lower part of the eight inferior ribs and intercostal muscles, the cremaster, the spermatic cord in the male, and the round ligament in the female. The upper border of the external oblique is continuous with the pectoralis major. The external oblique is now to be removed by making an incision across the ribs, just below its origin, to its posterior border ; and another along Poupart’s ligament and the crest of the ilium. Poupart’s liga- ment should be left entire, as it gives attachment to the next muscles. The muscle may then be turned forwards towards the linea alba, or removed altogether. The INTERNAL OBLIQUE MUSCLE (obliquus internus abdominis, as- cendens), is the middle flat muscle of the abdomen. It arises from the outer half of Poupart’s ligament, from the middle of the crest of the ilium for two-thirds of its length, and by a thin aponeurosis from the spinous processes of the lumbar vertebra. Its fibres diverge from their origin, so that those from Poupart’s ligament curve downwards, those from the anterior part of the crest of the ilium pass transversely, and the rest ascend obliquely. The muscle is émserted into the pecti- neal line and crest of the os pubis, linea alba, and lower borders of the five inferior ribs. Along the upper three fourths of the linea semilunaris, the aponeu- rosis of the internal oblique separates into two lamella, which pass one in front and the other behind the rectus muscle to the linea alba, where they are inserted ; along the lower fourth, the aponeurosis passes altogether in front of the rectus without separation. The two layers, which thus enclose the rectus, form for it a partial sheath. The lowest fibres of the internal oblique are inserted into the pecti- neal line of the os pubis in common with those of the transversalis muscle. Hence the tendon of this insertion is called the conjoined tendon of the internal oblique and transversalis, This structure corres- ponds with the external abdominal ring, and forms a protection to what would otherwise be a weak point in the abdomen. Sometimes the tendon is insufficient to resist the pressure from within, and becomes forced through the external ring ; it then forms the distinctive covering of direct inguinal hernia. The spermatic cord passes beneath the arched border of the internal oblique muscle, between it and Poupart’s ligament. During its pas- sage some fibres are given off from the lower border of the muscle, which accompany the cord downwards to the testicle, and form loops around it: this is the cremaster muscle. In the descent of oblique inguinal hernia, which travels the same course with the spermatic cord, the cremaster muscle forms one of its coverings. 214 MUSCLES OF THE ABDOMEN. Fig. 92.* * The muscles of the anterior aspect of the trunk; on the left side the su- perficial layer is seen, and on the right the deeper layer. 1. The pectoralis major muscle. 2. The deltoid; the interval between these muscles lodges the cephalic vein. 3. The anterior border of the latissimus dorsi. 4. The serra- tions of the serratus magnus. 5. The subclavius muscle of the right side. 6. The pectoralis minor. 7. The coraco-brachialis muscle. 8. The upper part of the biceps muscle, shewing its two heads. 9. The coracoid process of the scapula. 10. The serratus magnus of the right side. 11, The external inter- costal muscle of the fifth intercostal space. 12. The external oblique muscle. 13. Its aponeurosis ; the median line to the right of this number is the linea alba; the flexuous line to its left is the linea semilunaris; and the transverse lines above and below the number, the lineze transverse. 14. Poupart’s liga- ment. 15, The external abdominal ring; the margin above the ring is the CREMASTER.—TRANSVERSALIS. 215 The CREMASTER, considered as a distinct muscle, arises from the middle of Poupart’s ligament, and forms a series of loops upon the spermatic cord. A few of its fibres are inserted into the tu- nica vaginalis, the rest ascend along the inner side of the cord, to be inserted, with the conjoined tendon, into the pectineal line of the os pubis. Relations.—The internal oblique is in relation by its eaternal surface with the external oblique, latissimus dorsi, spermatic cord, and external abdominal ring. By its internal surface with the transversalis muscle, the fascia transversalis, the internal abdominal ring, and spermatic cord. By its lower and arched border with the spermatic cord, form- ing the upper boundary of the spermatic canal. The cremaster is in relation by its external surface with the aponeu- rosis of the external oblique and inter-columnar fascia; and by its zn- ternal surface with the fascia propria of the spermatic cord. The internal oblique muscle is to be removed by separating it from its attachments to the ribs above, and to the crest of the ilium and Poupart’s ligament below. It should be divided behind by a vertical incision extending from the last rib to the crest of the ilium, as its lumbar attachment cannot at present be examined. The muscle is then to be turned forwards. Some degree of care will be required in performing this dissection from the difficulty of distinguishing between this muscle and the one beneath. A thin layer of cellular tissue is all that separates them for the greater part of their extent. Near the crest of the ilium the circumflexa ilii artery ascends between the two muscles, and forms a valuable guide to their separation. Just above Poupart’s ligament they are so closely connected that it is impossible to divide them. The TRANSVERSALIS is the internal flat muscle of the abdomen ; it is transverse in the direction of its fibres, as is implied in its name. It arises from the outer third of Poupart’s ligament, from the internal lip of the crest of the ilium, its anterior two-thirds; from the spinous and transverse processes of the lumbar vertebrae, and from the inner surfaces of the six inferior ribs, indigitating with the diaphragm. Its lower fibres curve downwards, to be inserted, with the lower fibres of the internal oblique, into the pectineal line, and form the conjoined tendon. Throughout the rest of its extent it is inserted into the crest of the os pubis and linea alba. The lower fourth of its aponeurosis superior or internal pillar; the margin below the ring, the inferior or external pillar; the curved intercolumnar fibres are seen proceeding upwards from Pou- part’s ligament to strengthen the ring. The numbers 14 and 15 are situated upon the fascia lata of the thigh ; the opening immediately to the right of 15 is the saphenous opening. 16. The rectus muscle of the right side brought into view by the removal of the anterior segment of its sheath: * the posterior seg- ment of its sheath with the divided edge of the anterior segment. 17. The pyramidalis muscle. 18. The internal oblique muscle. 19. The conjoined tendon of the internal oblique and transversalis descending behind Poupart’s ligament to the pectineal line. 20. The arch formed between the lower curved border of the internal oblique muscle and Poupart’s ligament; it is beneath this arch that the spermatic cord and hernia pass, 216 MUSCLES OF THE ABDOMEN. passes in front of the rectus to the linea alba; the upper ¢hree-fourths, with the posterior lamella of the internal oblique behind it. _ The posterior aponeurosis of the transversalis divides into three la- * A lateral view of the trunk of the body, shewing its muscles, and particu- larly the transversalis abdominis. 1. The costal origin of the latissimus dorsi muscle, 2. The serratus magnus. 3. The upper part of the external oblique muscle divided in the direction best calculated to shew the muscles beneath without interfering with its indigitations with the serratus magnus. 4. Two of the external intercostal muscles. 5. Two of the internal intercostals. 6. The transversalis muscle. 7. Its posterior aponeurosis. 8. Its anterior aponeu- rosis forming the most posterior layer of the sheath of the rectus. 9. The lower part of the left rectus with the aponeurosis of the transversalis passing in front. 10. The right rectus muscle. 11. The arched opening left between the lower border of the transversalis muscle and Poupart’s ligament, through which the spermatic cord and hernia pass. 12. The gluteus maximus, and medius, and tensor vaginee femoris muscles invested by fascia lata. RECTUS.—PYRAMIDALIS. 217 mellae ;—anterior, which is attached to the bases of the transverse pro- cesses of the lumbar vertebre ; middle, to the apices of the transverse processes ; and posterior, to the apices of the spinous processes. The anterior and middle lamellz enclose the quadratus lumborum muscle ; and the middle and posterior, the erector spine. The union of the posterior lamella of the transversalis with the posterior aponeurosis of the internal oblique, serratus posticus inferior, and latissimus dorsi, constitutes the lumbar fascia. Relations.—By its external surface with the internal oblique, the in- ternal surfaces of the lower ribs, and internal intercostal muscles. By its internal surface with the transversalis fascia, which separates it from the peritoneum, with the psoas magnus, and with the lower part of the rectus and pyramidalis. The spermatic cord and oblique inguinal hernia pass beneath the lower border, but have no direct relation with it. To dissect the rectus muscle, its sheath should be opened by a ver- tical incision extending from over the cartilages of the lower ribs to the front of the os pubis. The sheath may then be dissected off and turned to either side; this is easily done excepting at the line trans- verse, where a close adhesion subsists between the muscle and the ex- ternal boundary of the sheath. The sheath contains the rectus and pyramidalis muscle. The Recrus MUSCLE arises by a flattened tendon from the crest of the os pubis, and is imserted into the cartilages of the fifth, sixth, and seventh ribs. It is traversed by several tendinous zig-zag intersections, called lineze transverse. One of these is usually situated at the um- bilicus, two above that point, and sometimes one below. They are vestiges of the abdominal ribs of reptiles, and very rarely extend completely through the muscle. Relations.—By its eaternal surface with the anterior lamella of the aponeurosis of the internal oblique, below with the aponeurosis of the transversalis, and pyramidalis. By its internal surface with the ensiform cartilage, the cartilages of the fifth, sixth, seventh, eighth and ninth ribs, with the posterior lamella of the internal oblique, the peritoneum, and the epigastric artery and veins. The PyRAMIDALIS MUSCLE arises from the crest of the os pubis in front of the rectus, and is inserted into the linea alba at about midway between the umbilicus and the os pubis. It is enclosed in the same sheath with the rectus, and rests against the lower part of that muscle. This muscle is sometimes wanting. The rectus may now be divided across the middle, and the two ends drawn aside for the purpose of examining the mode of formation of its sheath. The sheath of the rectus is formed in front for the upper three- fourths of its extent, by the aponeurosis of the external oblique and the anterior lamella of the internal oblique, and behind by the poste- rior lamella of the internal oblique and the aponeurosis of the trans- versalis. At the commencement of the lower fourth, the posterior 218 MUSCLES OF THE ABDOMEN. wall of the sheath terminates in a thin curved margin, the apo- neuroses of the three muscles passing altogether in front of the rectus, The next two muscles can be examined only when the viscera of the abdomen are removed. To see the quadratus lumborum, it is also necessary to divide and draw aside the psoas muscle and the an- terior lamella of the aponeurosis of the transversalis. The QuADRATUS LUMBORUM muscle is concealed from view by the anterior lameila of the aponeurosis of the transversalis muscle, which is inserted into the bases of the transverse processes of the lumbar vertebree. When this lamella is divided, the muscle will be seen arising from the last rib, and from the transverse processes of the four upper lumbar vertebrae. It is izserted into the crest of the ilium and ilio-lumbar ligament. If the muscle be cut across or removed, the middle lamella of the transversalis will be seen attached to the apices of the transverse processes; the quadratus being enclosed be- tween the two lamelle as in a sheath. Relations. — Enclosed in the sheath formed by the transversalis muscle, it is in relation im front, with the kidney, the colon, the psoas magnus, and the diaphragm. Behind, but also separated by its sheath, with the erector spine. The Psoas PARVUs arises from the tendinous arches and interverte- bral substance of the last dorsal and first lumbar vertebra, and termi- nates in a long slender tendon which expands inferiorly and is inserted into the ilio-pectineal line and eminence. The tendon is continuous by its outer border with the iliac fascia. Relations.—It rests upon the psoas magnus, and is covered in by the peritoneum ; superiorly it passes beneath the ligamentum arcu- atum of the diaphragm. It is occasionally wanting. DiaPHRAGM.—To obtain a good view of this important inspiratory muscle, the peritoneum should be dissected from its under surface. It is the muscular septum between the thorax and abdomen, and is com- posed of two portions, a greater and a lesser muscle. The greater muscle arises from the ensiform cartilage ; from the inner surfaces of the six inferior ribs, indigitating with the transversalis ; and from the ligamentum arcuatum externum and internum. From these points, which form the internal circumference of the trunk, the fibres converge and are inserted into the central tendon. The ligamentum arcuatum externum is the upper border of the an- terior lamella of the aponeurosis of the transversalis: it arches across the origin of the quadratus lumborum muscle, and is attached by one extremity to the base of the transverse process of the first lumbar dig and by the other to the apex and lower margin of the last rib. The ligamentum arcuatum internum, or proprium, is a tendinous arch thrown across the psoas magnus muscle as it emerges from the chest. It is attached by one extremity to the base of the transverse process of the first lumbar vertebra, and by the other is continuous DIAPHRAGM. 219 with the tendon of the lesser muscle opposite the body of the second. The tendinous centre of the diaphragm is shaped like a trefoil leaf, of which the central leaflet points to the ensiform cartilage, and is the largest; the lateral leaflets, right and left, occupy the corresponding Fig. 94.* * The under or abdominal side of the diaphragm. 1, 2, 3. The greater mus- cle; the figure 1 rests upon the central leaflet of the tendinous centre; the number 2 on the left or smallest leaflet; and number 3 on the right leaflet. 4 The thin fasciculus which arises from the ensiform cartilage; a small trian- gular space is left on either side of this fasciculus, which is closed only by the serous membranes of the abdomen and chest. 5. The ligamentum arcuatum externum of the left side. 6. The ligamentum arcuatum internum. 7. A small arched opening occasionally found, through which the lesser splanchnic nerve passes. 8. The right or larger tendon of the lesser muscle ; a muscular fasciculus from this tendon curves to the left side of the greater muscle between the cesophageal and aortic openings. 9. The fourth lumbar vertebra. 10. The left or chorion tendon of the lesser muscle. 11. The aortic opening occupied by the aorta, which is cut short off. 12. A portion of the cesophagus issuing through the cesophageal opening; in this figure the esophageal opening is tendinous at its anterior part, a structure which is not uncommon. 13. The opening for the inferior vena cava, in the tendinous centre of the diaphragm, 14. The psoas magnus muscle passing beneath the ligamentum arcuatum internum; it has been removed on the opposite side to shew the arch more distinctly. 15. The quadratus lumborum passing beneath the ligamentum arcuatum externum ; this muscle has also been removed on the left side. 220 MUSCLES OF THE ABDOMEN. portions of the muscle; the right being the larger and more rounded, and the left smaller and lengthened in its form. . Between the sides of the ensiform cartilage and the cartilages of the adjoining ribs, is a small triangular space where the muscular fibres of the diaphragm are deficient. This space is closed only by peritoneum on the side of the abdomen, and by pleura within the chest. It is therefore a weak point, and a portion of the contents of the abdomen might, by violent exertion, be forced through it, producing phrenic, or diaphragmatic hernia. The lesser muscle of the diaphragm takes its origin from the bodies of the lumbar vertebrae by two tendons. The right, larger and longer than the left, arises from the anterior surface of the bodies of the second, third, and fourth vertebree ; and the left from the side of the second and third. The tendons form two large fleshy bellies (crwra), which ascend to be inserted into the central tendon. The inner fasciculi of the two crura cross each other in front of the aorta, and again diverge to surround the cesophagus, so as to present the appear- ance of a figure of eight. The anterior fasciculus of the decussation is formed by the right crus. The openings in the diaphragm are three: one, quadrilateral, in the tendinous centre, at the union of the right and middle leaflets, for the passage of the inferior vena cava; a muscular opening of an elliptic shape formed by the two crura, for the transmission of the esophagus and pneumogastrie nerves ; and a third, the aortic, which is formed by a tendinous arch thrown from the tendon of one crus to that of the other, beneath which pass the aorta, the right vena azygos, and thoracic duct. The great splanchnic nerves pass through openings in the lesser muscle on each side, and the lesser splanchnic nerves through the fibres which arise from the ligamentum arcuatum internum. Relations.—By its superior surface with the pleure, the pericar- dium, the heart, and the lungs. By its inferior swrface with the peri- toneum ; on the left with the stomach and spleen ; on the right with the convexity of the liver ; and behind with the kidneys, the supra- renal capsules, the duodenum, and the solar plexus. By its circum- _—_ with the ribs and intercostal muscles, and with the vertebral column, Actions.—The external oblique muscle, acting singly, would draw the thorax towards the pelvis, and twist the body to the opposite side. Both muscles, acting together, would flex the thorax directly on the pelvis. The internal oblique of one side draws the chest downwards and outwards: both together bend it directly forwards. Either transversalis muscle, acting singly, will diminish the size of the abdo- men on its own side, and both together will constrict the entire cylinder of the cavity. The recti muscles, assisted by the pyramidales, flex the thorax upon the chest, and, through the medium of the lines transverse, are enabled to act when their sheath is curved inwards by the action of the transversales. The pyramidales are tensors of the linea alba. The abdominal are expiratory muscles, and the chief agents of ~ MUSCLES OF THE PERINEUM. 221 expulsion ; by their action the foetus is expelled from the uterus, the urine from the bladder, the feeces from the rectum, the bile from the gall-bladder, the ingesta from the stomach and bowels in vomiting, and the mucous and irritating substances from the bronchial tubes, trachea, and nasal passages, during coughing and sneezing. To produce these efforts they all act together. Their violent and continued action pro- duces hernia ; and, acting spasmodically, they may occasion rupture of the viscera. The quadratus lumborum draws the last rib down- wards, and is an expiratory muscle ; it also serves to bend the verte- bral column to one or the other side. The psoas parvus is a tensor of the iliac fascia, and, taking its fixed origin from below, it may as- sist in flexing the vertebral column forwards. The diaphragm is an inspiratory muscle, and the sole agent in tranquil inspiration. When in action, the muscle is drawn downwards, its plane being rendered ob- lique from the level of the ensiform cartilage, to that of the upper lumbar vertebra. During relaxation it is convex, and encroaches consider- ably on the cavity of the chest, particularly at the sides, where it corresponds with the lungs. It assists the abdominal muscles power- fully in expulsion, every act of that kind being preceded or accom- panied by a deep inspiration. Spasmodic action of the diaphragm produces hiccough and sobbing, and its rapid alternation of contraction and relaxation, combined with laryngeal and facial movements, laugh- _ ing and crying. MUSCLES OF THE PERINEUM. The muscles of the perineum are situated in the outlet of the pelvis, and consist of two groups, one of which belongs especially to the organs of generation and urethra, the other to the termination of the alimentary canal. To these may be added the only pair of muscles which is proper to the pelvis, the coccygeus. The muscles of the peri- neal region in the male, are the Accelerator urinze, Erector penis, Compressor urethre, Transversus perinel, Sphincter ani, Levator ani, Coccygeus. Dissection —To dissect the perineum, the subject should be fixed in the position for lithotomy, that is, the hands should be bound to the soles of the feet, and the knees kept apart. An easier plan is the drawing of the feet upwards by means of a cord passed through a hook in the ceiling. Both of these plans of preparation have for their object the full exposure of the perineum. And as this is a dissection 222 MUSCLES OF THE PERINEUM. which demands some degree of delicacy and nice manipulation, a strong light should be thrown upon the part. Having fixed the subject, and drawn the scrotum upwards by means of a string or hook, carry an incision from the base of the scrotum along the ramus of the pubes and ischium and tuberosity of the ischium, to a point parallel with the apex of the coccyx ; then describe a curve over the coccyx to the same point on the opposite side, and continue the incision onwards along the opposite tuberosity, and along the ramus of the ischium and of the pubes, to the opposite side of the scrotum, where the two extremities may be connected by a transverse incision. This incision will com- pletely surround the perineum, following very nearly the outline of its boundaries. Now let the student dissect off the integument carefully from the whole of the included space, and he will expose the fatty cellular structure of the common superficial fascia, which exactly re- sembles the superficial fascia in every other situation. The common superficial fascia is then. to be removed to the same extent, exposing the superficial perineal fascia. This layer is also to be turned aside, when the muscles of the genital region of the perineum will be brought into view. The AccELERATORES URIN& (bulbo-cavernosus) arise from a ten- dinous point in the centre of the perineum and from the fibrous raphé of the two muscles. From these origins the fibres diverge, like the plumes of a pen ; the posterior fibres to be inserted into the ramus of the pubes and ischium ; the middle to encircle the corpus spongiosum, and meet upon its upper side ; and the anterior to spread out upon the corpus cavernosum on each side, and be inserted, partly into its fibrous structure, and partly into the fascia of the penis. The poste- rior and middle insertions of these muscles are best seen, by carefully raising one muscle from the corpus spongiosum and tracing its fibres. Relations.—By their superficial surface with the superficial perineal fascia, the dartos, the superficial vessels and nerves of the perineum, and on each side with the erector penis. By their deep surface with the corpus spongiosum and bulb of the urethra. The Erecror PENIS (ischio-cavernosus) arises from the ramus and tuberosity of the ischium, and curves around the root of the penis, to be inserted into the upper surface of the corpus cavernosum, where it is continuous with a strong fascia which covers the dorsum of the organ, the fascia penis. Relutions.—By its superficial surface with the superficial perineal fascia, the dartos, and the superficial perineal vessels and nerve. By its deep surface with the corpus cavernosum penis. The Compressor uRETHR# (Wilson’s and Guthrie’s muscles), consists of two portions ; one of which is ¢ransverse in its direction, and passes inwards, to embrace the membranous urethra ; the other is perpendicular, and descends from the pubes. The transverse portion, particularly described by Mr. Guthrie, arises by a narrow tendinous point, from the upper part of the ramus of the ischium, on each side, and divides into two fasciculi, which pass inwards and slightly up- ae ee eed ee es eer ree Ye ea eee COMPRESSOR URETHR&. 223 wards, and embrace the membranous portion of the urethra and Cowper’s glands. As they pass towards the urethra, they spread out and become fan-shaped, and are inserted into a tendinous raphé upon the upper and lower surfaces of the urethra, extending from the apex of the prostate gland, to which they are attached posteriorly, to the bulbous portion of the urethra, with which they are connected in front. When seen from above, these portions resemble two fans, connected by their expanded border along the middle line of the membranous urethra, from the prostate to the bulbous portion of the urethra. The same appearance is obtained by viewing them from below. The perpendicular portion described by Mr. Wilson, arises by two tendinous points from the inner surface of the arch of the pubes, on each side of, and close to, the symphysis. The tendinous origins soon become muscular, and descend perpendicularly, to be ixserted into the * The muscles of the perineum. 1. The acceleratores urinze muscles; the figure rests upon the corpus spongiosum penis. 2. The corpus cavernosum of one side. 3. The erector penis of one side. 4. The transversus perinei of one side. 5. The triangular space through which the deep perineal fascia is seen. 6. The sphincter ani; its anterior extremity is cut off. 7. The levator ani of the left side; the deep space between the tuberosity of the ischium (8) and the anus, is the ischio-rectal fossa; the same fossa is seen upon the opposite side. g. The spine of the ischium. 10. The left coceygeus muscle. The bounda- ries of the perineum are well seen in this engraving. } Mr. Tyrrell who made many careful dissections of the muscles of the peri- neum, did not observe this portion of the muscle; he considers Wilson’s mus- cle (with some other anatomists) to be the anterior fibres of the levator ani, not uniting beneath the urethra as described by Mr. Wilson; but inserted into a portion of the R pias fascia situated between the prostate gland and rectum, the recto-vesical fascia, 224 MUSCLES OF THE PERINEUM, upper fasciculus of the transverse portion of the muscle ; so that it is not a distinct muscle surrounding the membranous portion of the urethra, and supporting it as in a sling, as described by Mr. Wilson, but merely an upper origin of the transverse muscle. The compressor urethre may be considered either as two symme- trical muscles meeting at the raphé, or as a single muscle: I have adopted the latter course in the above description, as appearing to me the more consistent with the general connections of the muscle, and with its actions. The TRANSVERSUS PERINEI arises from the tuberosity-of the ischium on each side, and is znserted into the central tendinous point of the perineum.* Relations.—By its superficial surface with the superficial perineal fascia, and superficial perineal artery. By its deep surface with the deep perineal fascia, and internal pudic artery and veins. By its pos- terior border it is in relation with that portion of the superficial peri- neal fascia which passes back to become continuous with the deep fascia. To dissect the compressor urethre, the whole of the preceding muscles should be removed, so as to render the glistening surface of the deep perineal fascia quite apparent. The anterior layer of this fascia should then be carefully dissected away, and the corpus spongiosum penis divided through its middle, separated from the corpus caver- nosum, and drawn forwards, to put the membranous portion of the urethra, upon which the muscle is spread out, on the stretch. The muscle is, however, better seen in a dissection made from within the pelvis, after having turned down the bladder from its attachment to the os pubis, and removed a plexus of veins and the posterior layer of the deep perineal fascia. The SPHINCTER ANI is a thin and elliptical plane of muscle closely adherent to the integument, and surrounding the opening of the anus. It arises posteriorly in the superficial fascia around the coccyx, and by a fibrous raphé from the apex of that bone; and is inserted anteriorly into the tendinous centre of the perineum, and into the raphé of the integument, nearly as far forwards as the commencement of the scrotum. Relations.—By its superficial surface with the integument. By its deep surface with the internal sphincter, the levator ani, the cellular tissue and fat in the ischio-rectal fossa, and in front with the superfi- cial perineal fascia. The SPHINCTER ANI INTERNUS is a muscular ring embracing the extremity of the intestine, and formed by an aggregation of the cir- cular muscular fibres of the rectum. * I have twice dissected a perineum in which the transversus perinei was of large size, and spread out as it approached the middle line so as to become fan- shaped. The posterior fibres were continuous with those of the muscle of the opposite side; but the anterior were prolonged forwards upon the bulb and corpus spongiosum of the urethra as far as the middle of the penis, forming a broad layer which usurped the place and office of the accelerator urine. LEVATOR ANL—COCCYGEUS. 225 Part of the levator ani may be seen during the dissection of the anal portion of the perineum by removing the fat which surrounds the termination of the rectum in the ischio-rectal fossa. But, to study the entire muscle, a lateral section of the pelvis must be made by sawing through the pubes a little to one side of the symphysis, separating the bones behind at the sacro-iliac symphysis, and turning down the blad- der and rectum. The pelvic fascia is then to be carefully raised, be- ginning at the base of the bladder and proceeding upwards, until the whole extent of the muscle is exposed. The LevaTor ANI is a thin plane of muscular fibres, situated on each side of the pelvis. The muscle arises from the inner surface of the os pubis, from the spine of the ischium, and between those points from the angle of division between the obturator and the pelvic fascia. Its fibres descend to be inserted into the extremity of the coccyx into a fibrous raphé in front of that bone, into the lower part of the rectum, base of the bladder, and prostate gland. In the female this muscle is inserted into the coccyx and fibrous raphé, lower part of the rectum and vagina. ions.—By its eaternal or perineal surface, with a thin layer of fascia, by which, and by the obturator fascia, it is separated from the obturator internus muscle; with the fat in the ischio-rectal fossa, the deep perineal fascia, the levator ani, and posteriorly with the gluteus maximus. By its internal or pelvic surface with the pelvic fascia, which separates it from the viscera of the pelvis and peritoneum. The CoccyGEeuS MUSCLE is a tendino-muscular layer of a triangular form. It arises from the spine of the ischium, and is inserted into the side of the coceyx and lower part of the sacrum. Relations.— By its internal or pelvic surface, with the rectum ; by its external surface with the lesser and greater sacro-ischiatic ligaments. The muscles of the perineum in the female are the same as in the male, and have received analogous names. They are smaller in size, and are modified to suit the different form of the organs; they are— Constrictor vagine, Erector clitoridis, Transversus perinei, Compressor urethra, Sphincter ani, Levator ani, Cocvygeus. The Constrictor vagine is analogous to the acceleratores urine ; it is continuous posteriorly with the sphincter ani, interlacing with its fibres, and is inserted anteriorly into the sides of the corpora cavernosa, and fascia of the clitoris. The Transversus perinet is inserted into the side of the constrictor vaginze, and the levator ani into the side of the vagina. The other muscles are precisely similar in their attachments to those in the male. Q 226 MUSCLES OF THE PERINEUM. Actions.—The acceleratores urine being continuous at the middle line, and attached on each side to the bone, by means of their posterior fibres will support the bulbous portion of the urethra, and acting sud- -denly will propel the semen, or the last drops of urine from the canal. The posterior and middle fibres, according to Krause,* contribute to- wards the erection of the corpus spongiosum, by producing compres- sion upon the yenous structure of the bulb; and the anterior fibres, according to Tyrrell,+ assist in the erection of the entire organ by com- pressing the vena dorsalis, by means of their insertion into the fascia penis. The erector penis becomes entitled to its name from spreading out upon the dorsum of the organ, into a membranous expansion (fascia penis), which, according to Krause, compresses the dorsal vein during the action of the muscle, and especially after the erection of the organ has commenced. The transverse muscles serve to steady the tendinous centre, that the muscles attached to it may obtain a firm point of support. According to Cruveilhier, they draw the anus backwards during the expulsion of the feces, and antagonise the levatores ani which carry the anus forwards. The compressor urethre taking its fixed point from the ramus of the ischium at each side, can, says Mr. Guthrie, “compress the urethra so as to close it; I conceive completely, after the manner of a sphincter.” The transverse portion will also have a tendency to draw the urethra downwards, whilst the perpendicular portion will draw it upwards towards the os pubis. The inferior fasciculus of the transverse muscle, enclosing Cowper’s glands, will assist those bodies in evacuating their secretion. The eaternal sphincter being a cutaneous muscle contracts the integument around the anus, and by its attachment to the tendinous centre, and to the point of the coccyx, assists the levator ani in giving support to the opening during expulsive efforts. The internal sphincter contracts the extremity of the cylinder of the intestine.. The use of the levator ani is expressed in its name. It is the antagonist of the diaphragm and the rest of the expulsory muscles, and serves to support the rectum and vagina during their expulsive efforts. The levator ani acts in unison with the diaphragm, and rises and falls like that muscle in forcible respiration. Yielding to the propulsive action of the abdo- minal muscles, it enables the outlet of the pelvis to bear a greater force than a resisting structure, and on the remission of such action it restores the perineum to its original form. The coccygei muscles restore the coccyx to its natural position, after it has been pressed backwards during defecation or during parturition. * Miiller, Archiv fiir Anatomie, Physiologie, &c. 1837. + Lectures in the College of Surgeons. 1839. 227 MUSCLES OF THE UPPER EXTREMITY. The muscles of the upper extremity may be arranged into groups corresponding with the different regions of the limb, thus: Anterior Thoracic Region. Lateral Thoracic Region. Pectoralis major, Serratus magnus. Pectoralis minor, Subclavius. Anterior Scapular Region. Posterior Scapular Region. Subscapularis. Supra-spinatus, Infra-spinatus, Teres minor, Teres major. Acromial Region, Deltoid. Anterior Humeral Region. Posterior Humeral Region. Coraco-brachialis, Triceps. Biceps, Brachialis anticus. Anterior Brachial Region, Posterior Brachial Region. Superficial layer. Superficial layer. Pronator radii teres, Supinator longus, Flexor carpi radialis, Extensor carpi radialis longior, Palmaris longus, Extensor carpi radialis brevior, Flexor sublimis digitorum, Extensor communis digitorum, Flexor carpi ulnaris. Extensor minimi digiti, Extensor carpi ulnaris, Anconeus. Deep layer. Deep layer. Flexor profundus digitorum, Supinator brevis, Flexor longus pollicis, Extensor ossis metacarpi pollicis, Pronator quadratus. Extensor primi internodii pollicis, - Extensor secundi internodii pollicis, Extensor indicis. 228 MUSCLES OF THE UPPER EXTREMITY. Hanp. Radial Region (Thenar). Ulnar Region (Hypothenar). Abductor pollicis, Palmaris brevis, = Flexor ossis metacarpi(opponens), Abductor minimi digiti, _ Flexor brevis pollicis, Flexor brevis minimi digiti, Adductor pollicis. Adductor minimi digiti. Palmar Region. Lumbricales, Interossei palmares, Interossei dorsales, ANTERIOR THORACIC REGION: Pectoralis major, Pectoralis minor, Subclavius. Dissection.—Make an incision along the line of the clavicle, from the upper part of the sternum to the acromion process ; a second along the lower border of the great pectoral muscle, from the lower end of the sternum to the insertion of its tendon into the humerus; and con- nect the two by a third, carried longitudinally along the middle of the sternum. The integument and superficial fascia are to be dissected to- gether from off the fibres of the muscle, and always in the direction of their course. For this purpose the dissector, if he have the right arm, will commence with the lower angle of the flap; if the left, with the upper angle. He will thus expose the pectoralis major muscle in its whole extent. The PEcrorALis MAJOR muscle arises from the sternal two-thirds of the clavicle, from one half the breadth of the sternum its whole length, from the cartilages of all the true ribs, excepting the first and last, and from the aponeurosis of the external oblique muscle of the abdomen. It is inserted by a broad tendon into the anterior bicipital ridge of the humerus. That portion of the muscle which arises from the clavicle, is sepa- rated from that connected with the sternum by a distinct cellular in- terspace; hence we speak of the clavicular portion and sternal portion of the pectoralis major. The fibres from this very extensive origin converge towards a narrow insertion, giving the muscle a radiated ap- pearance. But there is a peculiarity about the formation of its tendon which must be carefully noted. The whole of the lower border is folded inwards upon the upper portion, so that the tendon is doubled upon itself. Another peculiarity results from this arrangement: the fibres of the upper portion of the muscle are inserted into the lower part of the bicipital ridge; and those of the lower portion, into the upper part. PECTORALIS.—SUBCLAVIUS. 229 Relations.—By its eaternal surface with the fibres of origin of the platysma myoides, the mammary gland, the superficial fascia and inte- gument. By its internal surface, on the thorax, with the clavicle, the sternum, the costal cartilages, intercostal muscles, subclavius, pectoralis minor, and serratus magnus; in the axilla, with the axillary vessels and glands. By its eaternal border with the deltoid, from which it is separated above by a cellular interspace lodging the cephalic vein and the descending branch of the thoracico-acromialis artery. Its lower border forms the anterior boundary of the axillary space. The pectoralis major is now to be removed by dividing its fibres” along the lower border of the clavicle, and then carrying the incision perpendicularly downwards, parallel to the sternum, and at about three inches from its border. Divide some loose cellular tissue, and several small branches of the thoracic arteries, and reflect the muscle outwards. We thus bring into view a region of considerable interest, in the mid- dle of which is situated the pectoralis minor. The PEcToORALIS MINOR arises by three digitations from the third, fourth, and fifth ribs, and is inserted into the anterior border of the coracoid process of the scapula by a broad tendon. Relations.—By its anterior surface with the pectoralis major and superior thoracic vessels and nerves, By its posterior surface with the ribs, the intercostal muscles, serratus magnus, axillary space, and axillary vessels and nerves. Its upper border forms the lower boun- dary of a triangular space bounded above by the costo-coracoid mem- brane, and internally by the ribs. In this space are found the axil- lary vessels and nerves, and in it the subclavian artery may be tied below the clavicle. The Susciavius muscle arises by a round tendon from the cartilage of the first rib, and is inserted into the under surface of the clavicle. This muscle is concealed by the costo-coracoid membrane, an extension of the deep cervical fascia, by which it is invested. Relations.—By its upper surface with the clavicle. By the lower with the subclavian artery and vein and brachial plexus, which sepa- rate it from the first rib. In froné with the pectoralis major, the costo- coracoid membrane being interposed. Actions.—The pectoralis major draws the arm against the thorax, while its upper fibres assist the upper part of the trapezius in raising the shoulder, as in supporting weights. The lower fibres depress the shoulder with the aid of the latissimus dorsi. Taking its fixed point from the shoulder, the pectoralis major assists the pectoralis minor, subclayius, and serratus magnus, in drawing up and expanding the chest. The pectoralis minor, in addition to this action, draws upon the coracoid process, and assists in rotating the scapula upon the chest. The subclavius draws the clavicle downwards and forwards, and thereby assists in steadying the shoulder. All the muscles of this group are agents in forced respiration, but are incapable of acting until the shoulders are fixed, 230 LATERAL THORACIC REGION. Lateral Thoracic Region. Serratus magnus. The SerRaTus MAGNUs (serratus, indented like the edge of a saw, ) arises by fleshy serrations from the nine upper ribs excepting the first, and extends backwards upon the side of the chest, to be éxserted into the whole length of the base of the scapula upon its anterior aspect. In structure the muscle is composed of three portions, a superior por- tion formed by two serrations attached to the second rib, and inserted into the inner surface of the superior angle of the scapula, a middle portion composed of the serrations connected with the third and fourth ribs, and inserted into the greater part of the posterior border, and an inferior portion consisting of the last five serrations which indigitate with the obliquus externus and form a thick muscular fasciculus which is inserted into the scapula near its inferior angle. Relations.—By its superficial surface with the pectoralis major and minor, the subscapularis, and the axillary vessels and nerves. By its deep surface with the ribs and intercostal muscles, to which it is con- nected by an extremely loose cellular tissue. Actions.—The serratus magnus is the great external inspiratory muscle, raising the ribs when the shoulders are fixed, and thereby in- creasing the cavity of the chest. Acting upon the scapula, it draws the shoulder forwards, as we see to be the case in diseased lungs, where the chest has become almost fixed from apprehension of the expanding action of the respiratory muscles, Anterior Scapular Region. Subscapularis. The SusscapuLaris muscle arises from the whole of the under sur- face of the scapula excepting the superior and inferior angle, and ter- minates by a broad and thick tendon, which is inserted into the lesser tuberosity of the humerus. The substance of the muscle is traversed by several intersecting membranous layers from which muscular fibres arise, the intersections being attached to the ridges on the surface of the scapula. Its tendon forms part of the capsule of the joint, glides over a large bursa which separates it from the base of the coracoid process, and is lined by a prolongation of the synovial membrane of the articulation. : Relations.— By its anterior surface with the serratus magnus, coraco- brachialis, and axillary vessels and nerves. By its posterior surface with the ' scapula, the subscapular vessels and nerves, and the shoulder, joint. Action.—It rotates the head of the humerus inwards, and is a powerful defence to the joint. "When the arm is raised, it draws the humerus downwards. POSTERIOR SCAPULAR REGION. 23] Posterior Scapular Region. Supra-spinatus, Teres minor, _ Infra-spinatus, Teres major. The Supra-spinATuS muscle (supra, above ; spina, the spine) arises from the whole of the supra-spinous fossa, and is zserted into the uppermost depression on the great tuberosity of the humerus. The tendon of this muscle cannot be well seen until the acromion process is removed. Relations.—By its upper surface with the trapezius, the clavicle, acromion, and coraco-acromion ligament. From the trapezius it is separated by a strong fascia. By its lower surface with the supra- spinous fossa, the supra-scapular vessels and nerve, and the upper part of the shoulder-joint, forming part of the capsular ligament. The InrRaA-sPINATUS (infra, beneath ; spina, the spine) is cover- ed in by a layer of tendinous fascia, which must be removed before the fibres of the muscle can be seen, the deltoid muscle having been previously turned down from its scapular origin. It arises from the whole of the infra-spinous fossa, and from the fascia above-mentioned, and is inserted into the middle depression upon the greater tuberosity of the humerus. Relations. — By its posterior surface with the deltoid, latissimus dorsi and integument. By its anterior surface with the infra-spinous fossa, superior and dorsal scapular vessels, and shoulder-joint ; its tendon being lined by a prolongation from the synovial membrane. By its «pper border it is in relation with the spine of the scapula, and by the dower with the teres minor, with which it is closely united. The TeREs MINOR muscle (¢erés, round) arises from the middle third of the inferior border of the scapula, and is inserted into the lower de- pression on the great tuberosity of the humerus. The tendons of these three museles, with that of the subscapularis, are in immediate contact with the shoulder-joint, and form part of its ligamentous capsuie, thereby preserving the solidity of the articulation. They are there- fore the structures most frequently Tuptured 1 in dislocation of the head of the humerus, Relations.— By its posterior suface with the deltoid, latissimus dorsi and integument. By its anterior surface with the inferior bor- der, and part of the dorsum of the scapula, the dorsalis scapule ves- sels, scapular head of the triceps, and shoulder-joint. By its upper border with the infra-spinatus ; and by the lower with the latissimus dorsi, teres major, and long head of the triceps. The TERES MAJoR muscle arises from the lower third of the inferior border of the scapula, encroaching a little upon its dorsal aspect, and is inserted into the posterior bicipital ridge. Its tendon lies immedi- ately behind that of the latissimus dorsi, from which it is separated by a synovial membrane. Relations.—By its posterior surface with the latissimus dorsi, sca- 232 ACROMIAL REGION. pular head of the triceps and integument. By its anderior surface with the subscapularis, latissimus dorsi, coraco-brachialis, short head of the biceps, axillary vessels, and branches of the brachial plexus. By its wpper border it is in relation with the teres minor, from which it is separated by the scapular head of the triceps, and by the lower it forms with the latissimus dorsi the lower and posterior border of the axilla. A large triangular space exists between the two teres muscles, which is divided into two minor spaces by the long head of the triceps. Actions,—The supra-spinatus raises the arm from the side; but only feebly, from the disadvantageous direction of the force, The infra-spinatus and teres minor are rotators of the head of the humerus outwards. The most important use of these three muscles is the pro- tection of the joint, and defence against displacement of the head of the humerus, in which action they co-operate with the subscapularis. The teres major combines, with the latissimus dorsi, in rotating the arm inwards, and at the same time carrying it towards the side, and somewhat backwards, Acromial Region. Deltoid. The convexity of the shoulder is formed by a large triangular muscle, the deltoid (A, delta ; fF Ys jj : ‘ \ : I | © : \ * The carotid arteries with the branches of the external carotid. 1. The common carotid. 2. The external carotid. 3. The internal carotid. 4. The carotid foramen in the petrous portion of the temporal bone. 5. The superior thyroid artery. 6. The obey artery. 7. The facial artery. 8. The mastoid artery. 9. The occipital. 10. The posterior auricular. 11, The transverse facial artery, 12. The internal maxillary. 13. The temporal. 14. The ascend- ing pharyngeal artery. LINGUAL ARTERY. ; 303 Branches. —Hyoid, Superior laryngeal, Inferior laryngeal, Muscular. The Hyoid branch passes forwards beneath the thyro-hyoideus, and is distributed to the depressor muscles of the os hyoides near their insertion. The Superior laryngeal pierces the. thyro-hyoidean membrane, in company with the superior laryngeal nerve, and supplies the mucous membrane and muscles of the larynx, sending a branch upwards to the epiglottis. The Inferior laryngeal is a small branch which crosses the crico- thyroidean membrane along the lower border of the thyroid cartilage. It sends branches through the membrane to supply the mucous lining of the larynx, and inosculates with its fellow of the opposite side. The Muscular branches are distributed to the depressor muscles of the os hyoides and larynx. One of these branches crosses the sheath of the common carotid to the under surface of the sterno-mastoid muscle. 2. The LincuaL artery ascends obliquely from its origin, it then _ passes forwards parallel with the os hyoides; thirdly, it ascends to the under surface of the tongue ; and fourthly, runs forward in a ser- pentine direction to its tip, under the name of the ranine artery, where it terminates by inosculating with its fellow of the opposite side. Relations.—The first part of its course rests upon the middle con- strictor muscle of the pharynx, being covered in by the tendon of the digastricus and the stylo-hyoid muscle ; the second is situated be- tween the middle constrictor and hyo-glossus muscle, the latter sepa- rating it from the hypoglossal nerve ; in the third part of its course it lies between the hyo-glossus and genio-hyo-glossus ; and in the fourth (ranine) rests upon the lingualis to the tip of the tongue, Branches. —Hyoid, Dorsalis linguz, Sublingual. The Hyoid branch runs along the upper border of the os hyoides, and is distributed to the elevator muscles of the os hyoides near their origin, inosculating with its fellow of the opposite side. The Dorsalis lingue ascends along the posterior border of the hyo-glossus muscle to the dorsum of the tongue, and is distributed to the tongue, the fauces, and epiglottis, anastomosing with its fellow of the opposite side. The Sublingual branch, sometimes considered as a branch of bifurca- tion of the lingual, runs along the anterior border of the hyo-glossus, and is distributed to the sublingual gland and to the muscles of the 304 FACIAL ARTERY. tongue. Itis situated between the mylo-hyoideus and genio-hyo-glos- sus, generally accompanies Wharton’s duct for a part of its course, and sends a branch to the freenum lingue. It is the latter branch which affords the considerable hemorrhage which sometimes follows the operation of snipping the freenum in children. 3. FaciaL aRTERY.—The Facial artery arises a little above the great cornu of the os hyoides, and descends obliquely to the submax- illary gland, in which it lies embedded. It then curves around the body of the lower jaw, close to the anterior inferior angle of the mas- seter muscle, ascends to the angle of the mouth, and thence to the angle of the eye, where it is named the angular artery. The facial artery is tortuous in its course over the buccinator muscle, to accom- modate itself to the movements of the jaws. Relations.—Below the jaw it passes beneath the digastricus and stylo-hyoid muscles ; on the body of the lower jaw it is covered by the platysma myoides, and at the angle of the-mouth by the depressor anguli oris and zygomatic muscles. It rests upon the submaxillary gland, the lower jaw, buccinator, orbicularis oris, levator anguli oris, levator labii superioris proprius, and levator labii superioris aleeque nasi. Its branches are divided into those which are given off below the jaw and those on the face: they may be thus arranged :— Below the Jaw.—Inferior palatine, Submaxillary, Pterygoid. On the Face.—Masseteric, Inferior labial, Inferior coronary, Superior coronary, Lateralis nasi. The Inferior palatine branch ascends between the stylo-glossus and stylo-pharyngeus muscles, to be distributed to the tonsil and soft palate, and anastomoses with the posterior palatine branch of the internal maxillary artery. The Submazillary are four or five branches which supply the sub- maxillary gland. The Submental branch runs forwards upon the mylo-hyoid muscle, under cover of the body of the lower jaw, and anastomoses with branches of the sublingual and inferior dental artery. a Pterygoid branch is distributed to the internal pterygoid muscle. The Masseteric branches are distributed to the masseter and bucci- nator muscles, ee ee ee ee ee ee meee ee Oe ee ge ey OCCIPITAL.—POSTERIOR AURICULAR. 305 The Inferior labial branch is distributed to the muscles and integu- ment of the lower lip. The Inferior coronary runs along the edge of the lower lip, between the mucous membrane, and the orbicularis oris ; it inosculates with the corresponding artery of the opposite side. The Superior coronary follows the same course along the upper lip, inosculating with the opposite superior coronary artery, and at the middle of the lip it sends a branch upwards to supply the septum of the nose and the mucous membrane. The Lateralis nasi is distributed to the ala and septum of the nose. The Inoseulations of the facial artery are very numerous: thus, it anastomoses with the sublingual branch of the lingual, with the ascending pharyngeal and posterior palatine arteries, with the inferior dental as it escapes from the mental foramen, infra-orbital at the in- fra-orbital foramen, transverse facial on the side of the face, and at the angle of the eye with the nasal and frontal branches of the ophthalmic artery. The facial artery is subject to considerable variety in its extent ; it not unfrequently terminates at the angle of the nose or mouth, and is rarely symmetrical on both sides of the face. 4. The Masrom arrery turns downwards from its origin, to be distributed to the sterno-mastoid muscle, and to the lymphatic glands of the neck ; sometimes it is replaced by two small branches. 5. The Occtri1rAL ARTERY, smaller than the anterior branches, passes backwards beneath the posterior belly of the digastricus, the trachelo-mastoid and sterno-mastoid muscles, to the occipital groove in the mastoid portion of the temporal bone. It then ascends between the splenius and complexus muscles, and divides into two branches which are distributed upon the occiput, anastomosing with the oppo- site occipital, the posterior auricular, and temporal artery. The hypo- glossal nerve curves around this artery near its origin from the ex- ternal carotid. Branches.—It gives off only two branches deserving of name, the inferior meningeal and princeps cervicis. _ The Inferior meningeal ascends by the side of the internal jugular vein, and passes through the foramen lacerum posterius, to be distri- buted to the dura mata. The Arteria princeps cervicis is a large and irregular branch. It descends the neck between the complexus and semi-spinalis colli, and inosculates with the profunda cervicis of the subclavian. This branch is the means of establishing a very important collateral circulation between the branches of the carotid and subclavian, after ligature of the common carotid artery. 6. The PosTerRioR AURICULAR ARTERY arises from the external carotid, above the level of the digastric and stylo-hyoid muscles, and ® 306 | TRANSVERSALIS FACIEL—-TEMPORAL ARTERY. ascends beneath the lower border of the parotid gland, and behind the concha, to be distributed by two branches to the external ear and side of the head, anastomosing with the occipital and temporal arteries ; some of its branches pass through fissures in the fibro-cartilage, to be distributed to the anterior surface of the pinna. The anterior auricu- lar arteries are branches of the temporal. Branches.—The posterior auricular gives off but one named branch, the stylo-mastoid, which enters the stylo-mastoid foramen to be distri- buted to the aqueeductus Fallopii and tympanum. 7. The ParoTmpEAN ARTERIES are four or five large branches which are given off from the external carotid whilst that vessel is situated in the parotid gland. ‘They are distributed to the structure of the gland, their terminal branches reaching the integument and the side of the face. 8. The AscENDING PHARYNGEAL ARTERY, the smallest of the branches of the external carotid arises from that trunk near its bi- furcation, and ascends between the internal carotid and the side of the pharynx to the base of the skull, where it divides into two branches ; meningeal, which enters the foramen lacerum posterius, to be distributed to the dura mater ; and pharyngeal. It supplies the pharynx, tonsils, and Eustachian tube. 9. The TRANSVERSALIS FACIEI arises from the external carotid whilst that trunk is lodged within the parotid gland ; it crosses the masseter muscle, lying parallel with and a little above Stenon’s duct ; and is distributed to the temporo-maxillary articulation, and to the muscles and integument on the side of the face, inosculating with the infra-orbital and facial artery. This artery is not unfrequently a branch of the temporal. 10. The TemporAL ARTERY is one of the two terminal branches of the external carotid. It ascends over the root of the zygoma ; and, at about an inch and a half above the zygomatic arch, divides into an anterior and a posterior temporal branch. The anterior temporal is distributed over the front of the temple and arch of the skull, and ana- stomoses with the opposite anterior temporal, and with the supra-orbi- tal and frontal artery. The posterior temporal curves upwards and backwards, and inosculates with its fellow of the opposite side, with the posterior auricular and occipital artery. The trunk of the temporal artery is covered in by the parotid gland and by the attrahens aurem muscle, and rests upon the temporal fascia. Branches.—Orbitar, Anterior auricular, Middle temporal. The Orbitar artery is a small branch, not always present, which Lin INTERNAL MAXILLARY ARTERY. 307 passes forwards immediately above the zygoma, between the two layers of the temporal fascia, and inosculates beneath the orbicularis palpebrarum with the palpebral arteries. The Anterior auricular arteries are distributed to the anterior por- tion of the pinna. The Middle temporal branch passes through an opening in the tem- poral fascia immediately above the zygoma, and supplies the temporal muscle inosculating with the deep temporal arteries. 11. The INTERNAL MAXILLARY ARTERY, the other terminal branch of the external carotid, has next to be examined. Dissection.—The Internal mazxillary artery passes inwards behind the neck of the lower jaw to the deep structures in the face ; we re- quire, therefore, to remove several parts for the purpose of seeing it completely. To obtain a good view of the vessel, the zygoma should be sawn across in front of the external ear, and the malar bone near the orbit. Turn down the zygomatic arch with the masseter muscle. In doing this a small artery and nerve will be seen crossing the sigmoid notch of the lower jaw, and entering the masseter muscle (the masseteric). Cut away the tendon of the temporal muscle from its insertion into the coronoid process and turn it upwards towards its origin ; some vessels will be seen entering its under surface ; these are the deep temporal. Then saw the ramus of the jaw across its middle, and dislocate it from its articulation with the temporal bone. Be careful in doing this to carry the blade of the knife close to the bone, — lest any branches of nerves should be injured. Next raise this por- tion of bone, and with it the external pterygoid muscle. The artery, together with the deep branches of the inferior maxillary nerve, will be seen lying upon the pterygoid muscles. These are to be carefully freed from fat and areolar tissue, and then examined. This artery (fig. 117, No. 12) commences in the substance of the parotid gland, opposite the meatus auditorius externus ; it passes in the first instance horizontally forwards behind the neck of the lower jaw ; next, curves around the lower border of the external pterygoid muscle near its origin, and ascends obliquely forwards upon the outer side of that muscle ; it then passes between the two heads of the external pterygoid and enters the ‘pterygo-maxillary fossa. Occasionally it passes between the two pterygoid muscles, without appearing on the outer surface of the external pterygoid. In consideration of its course this artery may be divided into three portions: maxillary, pterygoid, and spheno-maxillary. Relations.—The maaillary portion is situated between the ramus of the jaw and the internal lateral ligament, lying parallel with the auri- cular nerve; the pterygoid portion between the external pterygoid muscle, and the masseter and temporal muscle. The pterygo-maaillary portion lies between the two heads of the external pterygoid muscle, and in the spheno-maxillary fossa is in relation with Meckel’s gan- glion. 308 INTERNAL MAXILLARY ARTERY. Branches. Maxillary Portion. Pterygoid Portion. Tympanic, Deep temporal branches, Inferior dental, External pterygoid, Arteria meningea media, Internal pterygoid, Arteria meningea parva. Masseteric, Buccal. Pterygo-maxillary Portion. Superior dental, Infra-orbital, Pterygo-palatine, Spheno-palatine, Posterior palatine, Vidian. The Tympanic branch is small and not likely to be seen in an ordi- nary dissection ; it is distributed to the temporo-maxillary articulation and meatus, and passes into the tympanum through the fissura Glasseri. The Inferior dental descends to the dental foramen, and enters the canal of the lower jaw in company with the dental nerve. Opposite the bicuspid teeth it divides into two branches, one of which is conti- nued onwards within the bone as far as the symphysis, to supply the incisor teeth, while the other escapes with the nerve at the mental fo- ramen, and anastomoses with the inferior labial and submental branch of the facial. -It supplies the teeth of the lower jaw, sending small branches along the canals in their roots. The Arteria meningea media ascends behind the temporo-maxillary articulation to the foramen spinosum in the spinous process of the sphenoid bone, and, entering the cranium, divides into an anterior and a posterior branch. The anterior branch crosses the great ala of the sphenoid to the groove or canal in the anterior inferior angle of the parietal bone, and divides into branches, which ramify upon the exter- nal surface of the dura mater, and anastomose with corresponding branches from the opposite side. The posterior branch crosses the squa- mous portion of the temporal bone, to the posterior part of the dura mater and cranium. The branches of the arteria meningea media are distributed chiefly to the bones of the skull; in the middle fossa it sends a small branch through the hiatus Fallopii to the facial nerve. The Meningea parva is a small branch which ascends to the foramen ovale, and passes into the skull to be distributed to the Casserian gan- - and dura mater. It gives off a twig to the nasal fosse and soft palate. The Muscular branches are distributed, as their names imply, to the five muscles of the maxillary region; the temporal branches (tempo- rales profund) are two in number. The Superior dental artery is given off from the internal maxillary, + A Nal angen ne cog s sebelndh coms = phic bi a eee epg ae pm Ae aaan= er tee oe te ee ey ee < aan INTERNAL CAROTID ARTERY. 309 just as that vessel is about to make its turn into the spheno-maxillary fossa. It descends upon the tuberosity of the superior maxillary bone, and sends its branches through several small foramina to supply the posterior teeth of the upper jaw, and the antrum. The terminal branches are continued forwards upon the alveolar process, to be dis- tributed to the gums and to the sockets of the teeth. The Jnfra-orbital would appear, from its size, to be the proper con- tinuation of the artery. It runs along the infra-orbital canal with the superior maxillary nerve, sending branches into the orbit and down- wards through canals in the bone, to supply the mucous lining of the antrum and the teeth of the upper jaw, and escapes from the infra- orbital foramen. The branch which supplies the incisor teeth is the anterior dental artery ; on the face the infraorbital inosculates with the facial and transverse facial arteries. The Pterygo-palatine is a small branch which passes through the pterygo-palatine canal, and supplies the upper part of the pharynx and Eustachian tube. The Spheno-palatine, or nasal, enters the superior meatus of the nose through the spheno-palatine foramen in company with the nasal branches of Meckel’s ganglion, and divides into two branches; one of which is distributed in the mucous membrane of the septum, while the other supplies the mucous membrane of the lateral wall of the nares, together with the sphenoid and ethmoid cells. - The Posterior palatine artery descends along the posterior palatine canal, in company with the posterior palatine branches of Meckel’s ganglion, to the posterior palatine foramen; it then curves forwards lying in a groove upon the bone, and is distributed to the palate. While in the posterior palatine canal it sends a branch backwards, through the small posterior palatine foramen to supply the soft palate, and anteriorly it distributes a branch to the anterior palatine canal, which reaches the nares and inosculates with the branches of the spheno-palatine artery. The Vidian branch passes backwards along the pterygoid canal, and is distributed to the sheath of the Vidian nerve, and to the Eustachian tube. INTERNAL CAROTID ARTERY. The internal carotid artery curves slightly outwards from the bifur- cation of the common carotid, and then ascends nearly perpendicularly through the maxillo-pharyngeal space* to the carotid foramen in the petrous bone. It next passes wnwards, along the carotid canal, for- wards by the side of the sella turcica, and upwards by the anterior clinoid process, where it pierces the dura mater and divides into three terminal branches. The course of this artery is remarkable for the number of angular curves which it forms; one or two of these flexures * For the boundaries of this space see page 189. 310 INTERNAL CAROTID ARTERY. are sometimes seen in the cervical portion of the vessel near the base of the skull; and by the side of the sella turcica it resembles the italic letter s, placed horizontally. Relations.—In consideration of its connections, the artery is divi- sible into a cervical, petrous, cavernous, and cerebral portion. The Cervical portion is in relation posteriorly with the rectus anticus major, sympathetic nerve, pharyngeal and laryngeal nerves which cross behind it, and near the carotid foramen with the glosso-pharyn- geal, pneumogastric and lingual nerves, and partially with the internal jugular vein. Internally it is in relation with the side of the pharynx, the tonsil, and the ascending pharyngeal artery. Hxternally with the internal jugular vein, glosso-pharyngeal, pneumogastric, and hypoglossal nerves; and in front with the stylo-glossus, and stylo-pharyngeus muscle, glosso-pharyngeal nerve, and parotid gland. Plan of the relations of the cervical portion of the internal carotid artery. In Front. Parotid gland, Stylo-glossus muscle, Stylo-pharyngeus muscle, Glosso-pharyngeal nerve. Internally. Ezternally. Pharynx, Internal Jugular vein, Tonsil, Carotid Artery. Glosso-pharyngeal, Ascending pharyn- Pneumogastric, geal artery, Hypoglossal nerve. Behind. Superior cervical ganglion, Pneumogastric nerve, Glosso-pharyngeal, Pharyngeal nerve, _ Superior laryngeal nerve, Sympathetic nerve, Rectus anticus major. The Petrous portion is separated from the bony wall of the carotid canal by a lining of dura mater; it is in relation with the carotid plexus, and is covered in by the Casserian ganglion. The Cavernous portion is situated in the inner wall of the cavernous sinus, and is in relation by its outer side with the lining membrane of the sinus, the sixth nerve, and the ascending branches of the carotid plexus. The third, fourth, and ophthalmic nerves are placed in the outer wall of the cavernous sinus, and are separated from the artery by the lining membrane of the sinus. The Cerebral portion of the artery is enclosed in a sheath of the arachnoid, and is in relation with the optic nerve. At its point of division it is situated in the fissure of Sylvius, La” OP eee eked STi- Ie OWN na She a a a faa OPHTHALMIC ARTERY. 311 Branches.—The cervical portion of the internal carotid gives off no branches: from the other portions are derived the following :— Tympanic, Anterior meningeal, Ophthalmic, Anterior cerebral, Middle cerebral, Posterior communicating, Choroidean. The Tympanic is a small branch which enters the tympanum through a minute foramen in the carotid canal. The Anterior meningeal is distributed to the dura mater and Cas- serian ganglion. The Ophthalmic artery arises from the cerebral portion of the inter- nal carotid, and enters the orbit through the foramen opticum, imme- diately to the outer side of the optic nerve. It then crosses the optic nerve to the inner wall of the orbit, and runs along the lower border of the superior oblique muscle, to the inner angle of the eye, where it divides into two terminal branches, the frontal and nasal. Branches.—The branches of the ophthalmic artery may be arranged into two groups: first, those distributed to the orbit and surrounding parts ; and secondly, those which supply the muscles and globe of the eye. They are— First Group. Second Group. Lachrymal, Muscular, Supra-orbital, Anterior ciliary, Posterior ethmoidal, Ciliary short and long, Anterior ethmoidal, Centralis retine. Palpebral, Frontal, Nasal. The Lachrymal is the first branch of the ophthalmic artery, and is usually given off immediately before that artery enters the optic fora- men. It follows the course of the lachrymal nerve, along the upper border of the external rectus muscle, and is distributed to the lachrymal gland. The small branches which escape from the gland supply the conjunctiva and upper eyelid. The lachrymal artery gives off a malar branch which passes through the malar bone into the temporal fossa and inosculates with the deep temporal arteries, while some of its branches become subcutaneous on the cheek and anastomose with the transverse facial. The Supra-orbital artery follows the course of the frontal nerve, resting on the levator palpebree muscle; it passes through the supra- orbital foramen and divides into a superficial and deep branch, which are distributed to the muscles and integument of the forehead and to - 7. : 312 OPHTHALMIC ARTERY, the pericranium, At the supra-orbital foramen it sends a branch in- wards to the diploé, The Ethmoidal arteries, posterior and anterior, pass through the ethmoidal foramina, and are distributed to the falx cerebri and to the ethmoidal cells and nasal fosse. The latter accompanies the nasal nerve. The Palpebral arteries, superior and inferior, are given off from the ophthalmic, near the inner angle of the orbit; they encircle the eye- lids, forming a superior and an inferior arch near the borders of the lids, between the orbicularis palpebrarum and tarsal cartilage, At the outer angle of the eyelids the superior palpebral inosculates with the orbitar branch of the temporal artery. The inferior palpebral artery sends a branch to the nasal duct. The Frontal artery, one of the terminal branches of the ophthalmic, emerges from the orbit at its inner angle, and ascends along the mid- dle of the forehead. It is distributed to the integument, muscles, and . pericranium. The Nasal artery, the other terminal branch of the ophthalmic, passes out of the orbit above the tendo oculi, and divides into two branches; one of which inosculates with the angular artery, while the other, the dorsalis nasi, runs along the ridge of the nose and is distri- buted to the entire surface of that organ. The nasal artery sends a small branch to the lachrymal sac. The Muscular branches, usually two in number, superior and in- ferior, supply the muscles of the orbit ; and upon the anterior aspect of the globe of the eye give off the anterior ciliary arteries, which pierce the sclerotic near its margin of connection with the cornea, and are distributed to the iris. It is the congestion of these vessels that gives rise to the vascular zone around the cornea in iritis. The Ciliary arteries are divisible into three groups, short, long, and anterior. The Short ciliary are very numerous; they pierce the sclerotic around the entrance of the optic nerve, and supply the choroid coat and ciliary processes. The long ciliary, two in number, pierce the sclerotic on opposite sides of the globe of the eye, and pass forwards between it and the choroid to the iris. They form an arterial circle around the circumference of the iris by inosculating with each other, and from this circle branches are given off which ramify in the sub- stance of the iris, and form a second circle around the pupil. The an- terior ciliary are branches of the muscular arteries; they terminate in the great arterial circle of the iris. The Centralis retine artery pierces the optic nerve obliquely, and passes forwards in the centre of its cylinder to the retina, where it di- vides into branches, which ramify in the inner layer of that membrane. It supplies the retina, hyaloid membrane, and zonula ciliaris ; and, by means of a branch sent forwards through the centre of the vitreous rg ae in a tubular sheath of the hyaloid membrane, the capsule of e lens, Eee ie SUBCLAVIAN ARTERY. 313 The Anterior cerebral artery passes forwards in the great longitudinal fissure between the two hemispheres of the brain; then curves back- wards along the corpus callosum to its posterior extremity. It gives branches to the olfactory and optic nerves, to the under surface of the anterior lobes, the third ventricle, the corpus callosum, and the inner surface of the hemispheres. The two anterior cerebral arteries are connected soon after their origin by a short anastomosing trunk, the anterior communicating. The Middle cerebral artery, larger than the preceding, passes out- wards along the fissure of Sylvius, and divides into three principal branches, which supply the anterior and middle lobes, and the island of Reil. Near its origin it gives off the numerous small branches which enter the substantia perforata, to be distributed to the corpus striatum. The Posterior Communicating artery, very variable in size, some- times double, and sometimes altogether absent, passes backwards and inosculates with the posterior cerebral, a branch of the basilar artery. Occasionally it is so large as to take the place of the posterior cerebral artery. The Choroidean is a small branch which is given off from the in- ternal carotid, near the origin of the posterior communicating artery, and passes beneath the edge of the middle lobe of the brain to enter the descending cornu of the lateral ventricle. It is distributed to the choroid plexus, and to the walls of the middle cornu. SUBCLAVIAN ARTERY, The Subclavian artery, on the right side, arises from the arteria in- nominata, opposite the sterno-clavicular articulation, and on the left, from the arch of the aorta. The right is consequently shorter than the left, and is situated nearer to the anterior wall of the chest ; it is also somewhat greater in diameter, from being a branch of a branch, in place of a division from the main trunk. . The course of the subclavian artery is divisible, for the sake of precision and surgical observation, into three portions. The first portions of the right and left arteries differ in their course and relations in correspondence with their dissimilarity of origin. The other two portions are precisely alike on both sides. The first portion, on the right side, ascends obliquely outwards to the inner border of the scalenus anticus. On the deft side it ascends perpendicularly to the inner border of that muscle. The second portion curves outwards behind the scalenus anticus; and the third portion passes downwards and outwards beneath the clavicle, to the lower border of the first rib, where it becomes the axillary artery. Relations. —The first portion, on the right side, is in relation in front with the internal jugular and subclavian vein at their point of junction, and is crossed by the pneumogastric nerve, cardiac nerves, 314 SUBCLAVIAN ARTERY.—RELATIONS. and phrenic nerve. Behind and beneath it is invested by the pleura, is crossed by the right recurrent laryngeal nerve and vertebral vein, and is in relation with the transverse process of the seventh cervical vertebra. The first portion on the /eft side is in relation in front with the pleura, the vena innominata, the pneumogastric and phrenic nerves (which lie parallel to it), and the left carotid artery. To its inner side is the wsophagus; to its outer side the pleura; and behind, the thoracic duct, longus colli, and vertebral column. Plan of the relations of the first portion of the Right Subclavian Artery. In Front, Internal jugular vein, Subclavian vein, Pneumogastric nerve, Cardiac nerves, Phrenic nerve. Right Subclavian Artery. Behind and Beneath. Pleura, Recurrent laryngeal nerve, Vertebral vein, Transverse process of 7th cervical vertebra, Plan of the relations of the first portion of the Left Subclavian Artery. In Front. Pleura, Vena innominata, Pneumogastric nerve, Phrenic nerve, Left carotid artery. Inner Side. Clk signa: Ue Outer Side. sop subclavian artery. Pugin: Behind. Thoracic duct, Longus colli, Vertebral column, The Second portion is situated between the two scaleni, and is sup- ported by the margin of the first rib. The scalenus anticus separates it from the subclavian vein and phrenic nerve. Behind it is in rela- tion with the brachial plexus. The Third portion is in relation, in front with the subclavian vein RSNA aie x a ae SUBCLAVIAN ARTERY.—RELATIONS. 315 and subclavius muscle; behind with the brachial plexus and scalenus posticus ; below with the first rib; and above with the supra-scapu- lar artery and platysma, Plan of the relations of the third portion of the Subclavian Artery. Above. Supra-scapular artery, Platysma myoides, In Front. ee Behind. Subclavian vein, Subelavian artery, Brachial plexus. Subclavius. Third portion. Scalenus posticus. Below. First mb. Branches.—The greater part of the branches of the subclavian are given off from the artery before it arrives at the margin of the first Fig. 118.* * The branches of the right subclavian artery. 1. The arteria innominata. 2. The right carotid. 3. The first portion of the subclavian artery. 4. The second portion. 5. The third portion. 6. The vertebral artery. 7. The in- ferior thyroid. 8. The thyroid axis. 9. The superficialis cervicis. 10. The profunda cervicis. 11. The posterior scapular or transversalis colli. 12, The supra-scapular. 13. The internal mammary artery. 14. The superior intercostal. 316 VERTEBRAL AND BASILAR ARTERIES, rib. The profunda cervicis and superior intercostal frequently en- croach upon the second portion, and not unfrequently a branch or branches may be found proceeding from the third portion. The primary branches are five in number, the first three being ascending, and the remaining two descending; they are the— Vertebral, Inferior thyroid, Supra-scapular, Posterior scapular, Superficialis cervicis. Thyroid axis, Profunda cervicis, Superior intercostal, Internal mammary. The VERTEBRAL ARTERY is the first and the largest of the branches of the subclavian artery; it ascends through the foramina in the transverse processes of all the cervical vertebrae, excepting the last; then winds backwards around the articulating process of the atlas; and, piercing the dura mater, enters the skull through the foramen magnum. ‘The two arteries unite at the lower border of the pons Varolii, to form the basilar artery. In the foramina of the transverse processes of the vertebree the artery lies in front of the cervical nerves. Dr. John Davy* has observed that, when the vertebral arteries differ in size, the left is generally the larger: thus in ninety-eight cases he found the left vertebral the larger twenty-six times, and the right only eight. In the same number of cases he found a small band stretching across the cylinder of the basilar artery, near the junction of the two vertebral arteries, seventeen times, and in a few instances a small communicating trunk between the two vertebral arteries previ- ously to their union. I have several times seen this communicating branch, and have a preparation now before me in which it is ex- hibited. The BasiILaR ARTERY, so named from its position at the base of the brain, runs forwards to the anterior border of the pons Varolii, where it divides into four ultimate branches, two to either side. Branches.—The branches of the vertebral and basilar arteries are the following:— Lateral spinal, Posterior meningeal, Vertebral, < Anterior spinal, Posterior spinal, Inferior cerebellar, Transverse, Basilar, 4 Superior cerebellar, Posterior cerebral. * Edinburgh Medical and Surgical Journal, 1839. POSTERIOR CEREBRAL ARTERY. 317 The Lateral spinal branches enter the invertebral foramina, and are distributed to the spinal cord and to its membranes. Where the vertebral artery curves around the articular process of the atlas, it gives off several muscular branches. The Posterior meningeal are one or two small branches which enter the cranium through the foramen magnum, to be distributed to the dura mater of the cerebellar fossee, and to the falx cerebelli. One branch, described by Soemmering, passes into the cranium along the first. cervical nerve. The Anterior spinal is a small branch which unites with its fellow of the opposite side, on the front of the medulla oblongata, The artery formed by the union of these two vessels descends along the anterior aspect of the spinal cord, to which it distributes branches. The Posterior spinal winds around the medulla oblongata to the pos- terior aspect of the cord, and descends on either side, communicating very freely with the spinal branches of the intercostal and lumbar arteries. Near its commencement it sends a branch upwards to the fourth ventricle. The Inferior cerebellar arteries wind around the upper part of the medulla oblongata to the under surface of the cerebellum, to which they are distributed. They pass between the filaments of origin of the hypoglossal nerve in their course, and anastomose with the supe- ‘rior cerebellar arteries. The Zransverse branches of the basilar artery supply the pons Varolii, and adjacent parts of the brain. One of these branches, larger than the rest, passes along the crus cerebelli to be distributed to the anterior border of the cerebellum. This may be called the middle cerebellar artery. The Superior cerebellar arteries, two of the terminal branches of the basilar, wind around the crus cerebri on each side in relation with the fourth nerve, and are distributed to the upper surface of the cerebellum inosculating with the inferior cerebellar. This artery gives off a small branch which accompanies the seventh pair of nerves into the meatus auditorius internus. The Posterior cerebral arteries, the other two terminal branches of the basilar, wind around the crus cerebri at each side, and are dis- tributed to the posterior lobes of the cerebrum. They are separated from the superior cerebellar artery, near their origin, by the third pair of nerves, and are in close relation with the. fourth pair in their course around the crura cerebri. Anteriorly, near their origin, they give off a tuft of small vessels which enter the locus perforatus, and they re- ceive the posterior communicating arteries from the internal carotid. They also send a branch to the velum interpositum and plexus cho- roides. The communications established between the anterior cerebral arteries in front, and the internal carotids and posterior cerebral arteries behind, by the communicating arteries, constitute the circle of Willis. This remarkable communication at the base of the brain is 318 CIRCLE OF WILLIS. formed by the anterior communicating branch, anterior cerebrals, and internal carotid arteries in front, and by the posterior communicating, posterior cerebrals, and basilar artery behind. Fig. 119.* The THyroip Axis is a short trunk which divides almost immedi- * The circle of Willis. The arteries have references only on one side, on account of their symmetrical distribution. 1. The vertebral arteries. 2. The two anterior spinal branches uniting to form a single vessel. 3. One of the —, spinal arteries. 4. The posterior meningeal. 5. The inferior cere- ar. 6. The basilar artery giving off its transverse branches to either side. 7. The superior cerebellar artery. 8. The posterior cerebral. 9. The posterior communicating branch of the internal carotid. 10. The internal carotid artery, shewing the curvatures it makes within the skull. 11. The ophthalmic artery divided across. 12. The middle cerebral artery. 13. The anterior cerebral arteries connected by, 14. The anterior communicating artery. Sl eek oth ae De see oe POSTERIOR SCAPULAR ARTERY. 319. ately after its origin into four branches, some of which are occasionally branches of the subclavian artery itself. The INFERIOR THYROID ARTERY ascends obliquely in a serpentine course behind the sheath of the carotid vessels, to the inferior part of thyroid gland, to which it is distributed ; it sends branches also to the trachea, lower part of the larynx, and cesophagus. It is in relation with the middle cervical ganglion of the sympathetic, which lies in front of it. The Suprs-scAPULAR ARTERY (transversalis humeri) passes ob- liquely outwards behind the clavicle, and over the ligament of the supra-scapular notch, to the supra-spinatus fossa. It crosses in its course the scalenus anticus muscle, phrenic nerve, and subclavian artery, is distributed to the muscles on the dorsum of the scapula, and inosculates with the posterior scapular, and beneath the acromion pro- cess with the dorsal branch of the subscapular artery. At the supra- scapular notch it sends a large branch to the trapezius muscle. The supra-scapular artery is not unfrequently a branch of the subclavian. The PosrERIoR SCAPULAR ARTERY (transversalis colli) passes transversely across the subclavian triangle at the root of the neck, to the superior angle of the scapula. It then descends along the posterior border of that bone to its inferior angle, where it inosculates with the subscapular artery, a branch of the axillary. In its course across the neck it passes in front of the scalenus anticus, and across the brachial plexus ; in the rest of its course it is covered in by the trapezius, levator anguli scapulz, rhomboidous minor, and rhomboideus major muscles. Sometimes it passes behind the scalenus anticus, and between the nerves, which constitute the brachial plexus. This artery, which is very irregular in its origin, proceeds more frequently from the third portion of the subclavian artery than from the first. The posterior scapular gives branches to the neck, and opposite the angle of the scapula inosculates with the profundacervicis. It sup- plies the muscles along the posterior border of the scapula, and estab- lishes an important anastomotic communication between the branches of the external carotid, subclavian, and axillary arteries. The SuPERFICIALIS CERVICIS ARTERY (cervicalis anterior) is a small vessel, which ascends upon the anterior tubercles of the trans- verse processes of the cervical vertebrae, lying in the groove between the scalenus anticus and rectus anticus major. It is distributed to the deep muscles and glands of the neck, and sends branches through the intervertebral foramina to supply the spinal cord and its membranes. The PRoFUNDA CERVICIS (cervicalis posterior) passes backwards between the transverse processes of the seventh cervical and first dor- sal vertebra, and then ascends the back part of the neck, between the 320 INTERNAI MAMMARY ARTERY. complexus and semi-spinalis colli muscles. It inosculates above ‘with the princeps cervicis of the occipital artery. and below, by a descending branch, with the posterior scapular. The SuPERIOR INTERCOSTAL ARTERY descends behind the pleura upon the necks of the first two ribs, and inosculates with the first aortic intercostal. It gives off two branches which supply the first two in- tercostal spaces. The INTERNAL MAMMARY ARTERY descends by the side of the sternum, resting upon the costal cartilages, to the diaphragm; it then pierces the anterior fibres of the diaphragm ; and enters the sheath of the rectus, where it inosculates with the epigastric artery, a branch of the external iliac. In the upper part of its course it is crossed by the phrenic nerve, and lower down lies between the triangularis sterni and the internal intercostal muscles. The Branches of the internal mammary are,— Anterior intercostal, Mammary, Comes nervi phrenici, Mediastinal, Pericardiac, Musculo-phrenic. The Anterior intercostals supply the intercostal muscles of the front of the chest, and inosculate with the aortic intercostal arteries. Each of the first three anterior intercostals gives off a large branch to the mammary gland, which anastomoses freely with the thoracic branches - of the axillary artery; the corresponding branches from the remaining intercostals supply the integument and pectoralis major muscle. There are usually two anterior intercostal arteries in each space. The Comes nervi phrenici is a long and slender branch which accom- panies the phrenic nerve. The mediastinal and pericardiac branches are small vessels distri- buted to the anterior mediastinum, the thymus gland, and _peri- cardium. The Musculo-phrenic artery winds along the attachment of the diaphragm to the ribs, supplying that muscle and sending branches to the inferior intercostal spaces. “'The mammary arteries,” says Dr. Harrison, “are remarkable for the number of their inosculations, and for the distant parts of the arterial system which they serve to con- nect. They anastomose with each other, and their inosculations, with the thoracic aorta, encircle the thorax. On the parietes of this cavity their branches connect the axillary and subclavian arteries; on the diaphragm they form a link in the chain of inosculations between the subclavian artery and abdominal aorta, and in the parietes of the ab- domen they form an anastomosis most remarkable for the distance be- & - AXILLARY ARTERY. 321 tween those vessels which it serves to connect; namely, the arteries of the superior and inferior extremities.” Varieties of the subclavian Arteries.—Varieties in these arteries are rare; that which most frequently occurs is the origin of the right subclavian, from the left extremity of the arch of the aorta, below the left subclavian artery. The vessel, in this case, curves behind the cesophagus and right carotid artery, and sometimes between the ceso- phagus and trachea, to the upper border of the first rib on the right side of the chest, where it assumes its ordinary course. In a case* of subclavian aneurism on the right side, above the clavicle, which happened during the summer of 1839, Mr. Liston proceeded to per- form the operation of tying the carotid and subclavian arteries at their point of division from the innominata. Upon reaching the point where the bifurcation should have existed, he found that there was no sub- clavian artery. With that admirable self-possession which distinguishes this eminent surgeon in all cases of emergency, he continued his dis- section more deeply, towards the vertebral column, and succeeded in securing the artery. It was ascertained after death, that the arteria innominata was extremely short, and-that the subclavian was given off within the chest from the posterior aspect of its trunk, and pursued a deep course to the upper margin of the first rib. In a preparation which was shewn to me in Heidelberg some years since by Professor - Tiedemann, the right subclavian artery arose from the thoracic aorta, as low down as the fourth dorsal vertebra, and ascended from that point to the border of the first rib. Varieties in the branches of the subclavian are not unfrequent; the most interesting is the origin of the left vertebral, from the arch of the aorta, of which I possess several preparations. AXILLARY ARTERY. The azillary artery forms a gentle curve through the middle of the axillary space from the lower border of the first rib to the lower border of the latissimus dorsi, where it becomes the brachial. Relations.—After emerging from beneath the margin of the costo- coracoid membrane, it is in relation with the axillary vein, which lies at first to the inner side, and then in front of the artery. Near the middle of the axilla it is embraced by the two heads of the median nerye, and is covered in by the pectoral muscles. Upon the inner or ic side it is in relation, first, with the first intercostal muscle ; it next rests upon the first serration of the serratus magnus; and is then separated from the chest by the brachial plexus of nerves. By its outer or humeral side it is at first separated from the brachial plexus by a triangular cellular interval; it next rests against the tendon of the subscapularis muscle; and thirdly, upon the coraco- brachialis muscle. * This case is recorded in the Lancet, vol. i. 1839-49, pp. 37 and 419. > 322 AXILLARY ARTERY. Fig. 120.* * The axillary and brachial artery, with their branches. 1. The deltoid muscle. 2. The biceps. 3. The tendinous process given off from the tendon of the biceps, to the deep fascia of the fore-arm. It is this process which sepa- rates the median basilic vein from the brachial artery. 4. The outer border of the brachialis anticus muscle, 5. The supinator longus. 6. The coraco-bra- chialis. 7. The middle portion of the triceps muscle. 8. Its inner head. 9. The axillary artery. 10. The brachial artery ;—a dark line marks the limit between these two vessels. 11. The thoracica acromialis artery dividing into its three branches ; the number rests upon the coracoid process. 12. The superior and inferior thoracic arteries, 13. The serratus magnus muscle. 14. The sub- scapular artery. The posterior circumflex and thoracica axillaris branches are seen in the figure between the inferior thoracic and subscapular. The anterior circumflex is observed, between the two heads of the biceps, crossing the neck of the humerus. 15. The superior profunda artery. 16. The inferior pro- funda, 17. The anastomotica magna inosculating inferiorly with the anterior ulnar recurrent. 18. The termination of the superior profunda, inosculatin with the radial recurrent in the interspace between the brachialis anticus an supinator longus, 7 AXILLARY ARTERY.— BRANCHES. 323 The relations of the axillary artery may be thus arranged :— In Front. Inner or Thoracic Side. Outer or Humeral Side. Pectoralis major, First intercostal muscle, Plexus of nerves, Pectoralis minor, First serration of ser- Tendon of sub- Pectoralis major. ratus magnus, scapularis, Plexus of nerves. Coraco-brachialis. Branches.—The branches of the Avillary artery are seven in number :— Thoracica acromialis, Superior thoracic, Inferior thoracic, Thoracica axillaris, Subscapular, Circumflex anterior, Circumflex posterior. The thoracica acromialis and superior thoracic are found in the tri- angular space above the pectoralis minor. The inferior thoracic and thoracica axillaris, below the pectoralis minor. And the three re- maining branches below the lower border of the subscapularis. The Thoracica acromialis is a short trunk which ascends to the space above the pectoralis minor muscle, and divides into three branches, thoracic, which is distributed to the pectoral muscles and mammary gland ; acromial, which passes outwards to the acromion, and inoscu- lates with branches of the supra-scapular artery; and descending, which follows the interspace between the deltoid and pectoralis major muscles, and is in relation with the cephalic vein. The Superior thoracic (short) frequently arises by a common trunk with the preceding; it runs along the upper border of the pectoralis minor, and is distributed to the pectoral muscles and mammary gland, inosculating with the intercostal and mammary arteries. The Inferior thoracic (long external mammary) descends along the lower border of the pectoralis minor to the side of the chest. It is distributed to the pectoralis major and minor, serratus magnus, and subscapularis muscle, to the axillary glands and mammary gland ; inosculating with the superior thoracic, intercostal, and mammary arteries. : The Thoracica axillaris is a small branch distributed to the plexus of nerves and glands in the axilla. It is frequently derived from one of the other thoracic branches. The Subscapular artery, the largest of the branches of the axillary, runs along the lower border of the subscapularis muscle, to the inferior angle of the scapula, where it inosculates with the posterior scapular, a branch of the subclavian. It supplies, in its course, the muscles on the under surface and inferior border of the scapula, and the side of the 324 VARIETIES OF THE AXILLARY ARTERY. chest. At about an inch and a half from the axillary, it gives off a large branch, the dorsalis scapule, which passes backwards through the triangular space bounded by the teres minor, teres major, and sca- pular head of the triceps, and beneath the infra-spinatus to the dorsum of the scapula, where it is distributed, inosculating with the supra- scapular and posterior scapular arteries. The Circumflex arteries wind around the neck of the humerus. The anterior, very small, passes beneath the coraco-brachialis and short head of the biceps, and sends a branch upwards along the bicipital groove to supply the shoulder-joint. The Posterior circumflex, of larger size, passes backwards through the quadrangular space bounded by the teres minor and major, the scapular head of the triceps and the humerus, and is distributed to the deltoid muscle and joint. Sometimes this artery is a branch of the superior profunda of the brachial. It then ascends behind the tendon of the teres major, and is distributed to the deltoid without passing through the quadrangular space. The posterior circumflex artery sends branches to the shoulder-joint. Varieties of the axillary Artery.—The most frequent peculiarity of this kind is the division of the vessel into two trunks of equal size: a muscular trunk, which gives off some of the ordinary axillary branches and supplies the upper arm, and a continued trunk, which represents the brachial artery. The next most frequent variety is the high division of the ulnar which passes down the arm by the side of the brachial artery, and superficially to the muscles proceeding from the inner condyle, to its ordinary distribution in the hand. In this course it lies immediately beneath the deep fascia of the fore-arm, and may be seen and felt pulsating beneath the integument. The high division of the radial from the axillary is rare. In one instance, I saw the axillary artery divide into three branches of nearly equal size, which passed together down the arm, and at the bend of the elbow resolved themselves into radial, ulnar, and interosseous. But the most interesting variety, both in a physiological and surgical sense, is that described by Dr. Quain, in his “ Elements of Anatomy.” ‘‘I found in the dissecting-room, a few years ago, a variety not hitherto noticed ; it was at first taken for the ordinary high division of the ulnar artery. The two vessels descended from the point of division at the border of the axilla, and lay parallel with one another in their course through the arm; but instead of diverging, as is usual, at the bend of the elbow, they converged, and united so as to form a short trunk which soon divided again into the radial and ulnar arteries in the regular way.” In a subject, dissected by myself, this variety ex- me in both arms; and I have seen several instances of a similar ind, BRACHIAL ARTERY. 325 BRACHIAL ARTERY, The Brachial artery passes down the inner side of the arm, from the lower border of the latissimus dorsi to the bend of the elbow, where it divides into the radial and ulnar arteries, Relations.—In its course downwards, it rests upon the coraco- brachialis muscle, internal head of the triceps, brachialis anticus, and the tendon of the biceps. To its inner side is the ulnar nerve ; to the outer side, the coraco-brachialis and biceps muscles; in front it has the basilic vein, and is crossed by the median nerve. Its relations, within its sheath, are the venz comites. Plan of the relations of the Brachial Artery. In Front. Basilic vein, Deep fascia, Median nerve. Inner Side. Outer Side. Ulnar nerve. Brachial Artery. Coraco-brachialis, Biceps. Behind. Short head of triceps, Coraco-brachialis, Brachialis anticus, Tendon of Biceps. The branches of the brachial artery are, the— Superior profunda, Inferior profunda, Anastomotica magna, Muscular. The Superior profunda arises opposite the lower border of the latis- simus dorsi, and winds around the humerus, between the triceps and the bone, to the space between the brachialis anticus and supinator longus, where it inosculates with the radial recurrent branch. It ac- companies the musculo-spiral nerve. In its course it gives off the pos- terior articular artery, which descends to the elbow-joint, and a more superficial branch which inosculates with the interosseous articular. artery. The Inferior profunda arises from about the middle of the brachial artery, and descends to the space between the inner condyle and ole- . eranon in company with the ulnar nerve, where it inosculates with the posterior ulnar recurrent. The Anastomotica magna is given off nearly at right angles from the 326 ARTERIES OF THE FORE-ARM. Fig. 121.* y M4 — oeifie o * The arteries of the fore-arm. 1, The lower part of the biceps muscle 2. The inner condyle of the humerus with the tech oo origin of the pronator radii teres and flexor carpi radialis divided across. 3. The deep portion of the pronator radii teres. 4. The supinator longus muscle. 5. The flexor longus pollicis, 6. The pronator quadratus. 7. The flexor profundus digitorum. “i The flexor carpi ulnaris. 9. The annular ligament with the tendons passing —- it into the palm of the hand; the figure is placed on the tendon of the palmaris longus muscle, divided close to its insertion. 10. The brachial artery. 11. The anastomotica magna inosculating superiorly with the inferior profunda, ant inferiorly with the anterior ulna recurrent. 12. The radial artery. 13. e radial recurrent artery inosculating with the termination of the superior RADIAL ARTERY. 327 brachial, at about two inches above the joint. It passes directly in- wards, and divides into two branches which inosculate with the ante- rior and posterior ulnar recurrent arteries and with the inferior pro- funda. The Muscular branches are distributed to the muscles in the course of the artery, viz. to the coraco-brachialis, biceps, deltoid, brachialis auticus and triceps. Varieties of the brachial Artery—The most frequent peculiarity in the distribution of branches from this artery is the high division of the radial, which arises generally from about the upper third of the brachial artery, and descends to its normal position at the bend of the elbow. The ulnar artery sometimes arises from the brachial at about two inches above the elbow, and pursues either a superficial or deep course to the wrist; and, in more than one instance, I have seen the interosseous artery arise from the brachial a little above the bend of the elbow. The two profunda arteries occasionally arise by a common trunk, or there may be two superior profunde. RADIAL ARTERY. The Radial artery, one of the divisions of the brachial, appears from its direction to be the continuation of that trunk. It runs along the radial side of the fore-arm, from the bend of the elbow to the wrist; it there turns around the base of the thumb, beneath its extensor tendons, and passes between the two heads of the first dorsal in- terosseous muscle, into the palm of the hand. It then crosses the metacarpal bones to the ulnar side of the hand, forming the deep palmar arch, and terminates by inosculating with the superficial palmar arch. In the upper half of its course, the radial artery is situated between the supinator longus muscle, by which it is overlapped superiorly, and the pronator radii teres; in the lower half, between the tendons of the supinator longus and flexor carpi radialis, It rests in its course downwards, upon the supinator brevis, pronator radii teres, radial origin of the flexor sublimis, flexor longus pollicis, and pronator qua- dratus; and is covered in by the integument and fascie. At the wrist it is situated in contact with the dorsal carpal ligaments and beneath the extensor tendons of the thumb; and, in the palm of the hand, beneath the flexor tendons. It is accompanied by venz comites throughout its course, and by its middle third is in close relation with the radial nerve. profunda. 14. The superficialis vole. 15. The ulnar artery. 16. Its super- ficial palmar arch giving off digital branches to three fingers and a half. 17. The magna pollicis and radialis indicis arteries, 18. The posterior ulnar recur- rent. 19. The anterior interosseous artery. 20. The posterior interosseous, as it is passing through the interosseous membrane. 328 RADIAL ARTERY.—BRANCHES. Plan of the relations of the Radial Artery in the Fore-arm. In Front, . Deep fascia, Supinator longus. Inner Side. j Outer Side. Pronator radii teres Radial artery. © Supinator longus, - Flexor carpi radialis. 2 is Radial nerve (middle third of its course). Behind. Supinator brevis, Pronator radii teres, Flexor sublimis digitorum, Flexor longus pollicis, Pronator quadratus, Wrist-joint. The Branches of the radial artery may be arranged into three groups, corresponding with the three regions, the fore-arm, the wrist, and the hand ; they are— : RF Recurrent radial, , / Spruadetg Muscular. Superficialis vole, Carpalis anterior, Wrist, Carpalis posterior, Metacarpalis, Dorsales pollicis. Princeps pollicis, Radialis indicis, Interosseze, Perforantes. Hand, The Recurrent branch is given off immediately below the elbow ; it ascends in the space between the supinator longus and brachialis anti- cus to supply the joint, and inosculates with the terminal branches of the superior profunda. This vessel gives off numerous muscular branches. The Muscular branches are distributed to the muscles on the radial side of the fore-arm. | The Superficialis vole is given off from the radial artery while at the wrist. It passes between the fibres of the abductor pollicis muscle, and inosculates with the termination of the ulnar artery, completing the superficial palmar arch, This artery is very variable in size, being sometimes as large as the continuation of the radial, and at other times a mere muscular ramusculus, or entirely wanting; when of large size it supplies the palmar side of the thumb and the radial side of the index finger. ULNAR ARTERY. 329 The Carpal branches are intended for the supply of the wrist, the anterior carpal in front, and the posterior, the larger of the two, be- hind. The carpalis posterior crosses the carpus transversely to the ulnar border of the hand, where it inosculates with the posterior car- pal branch of the tlnar‘artery. Superiorly it sends branches which inosculate with the termination of the anterior interosseous:artery ; inferiorly, it gives off posterior interosseous branches, which anastomose with the perforating branches of the deep palmar arch, and then run forward upon the dorsal interossei muscles. The Metacarpal branch runs forward on the second dorsal interos- seous muscle, and inosculates with the digital branch of the superficial palmar arch, which supplies the adjoining sides of the index and mid- dle fingers. Sometimes it is of large size, and the true continuation of the radial artery. The Dorsales pollicis are two small branches which run along the sides of the dorsal aspect of the thumb. The Princeps pollicis descends along the border of the metacarpal bone, between the abductor indicis and adductor pollicis to the base of the first phalanx, where it divides into two branches, which are dis- _ tributed to the two sides of the palmar aspect of the thumb. -The Radialis indicis is also situated between the abductor indicis the adductor pollicis, and runs along the radial side of the index finger, forming its collateral artery. This vessel is frequently a branch of the princeps pollicis. The Jnterossee, three or four in number, are branches of the deep palmar arch; they pass forward upon the interossei muscles and in- osculate with the digital branches of the superficial arch, opposite the heads of the metacarpal bones. The Perforantes, three in number, pass directly backwards between the heads of the dorsal interossei muscles, and inosculate with the posterior interosseous arteries. ULNAR ARTERY. The Ulnar artery, the other division of the brachial artery, crosses the arm obliquely to the commencement of its middle third; it then runs down the ulnar side of the fore-arm to the wrist, crosses’ the an- nular ligament, and forms the superficial palmar arch, which terminates by inosculating with the superficialis vole. Relations.—In the upper or oblique portion of its course, it lies upon the brachialis anticus and flexor profundus digitorum ; and is covered in by the superficial layer of muscles of the fore-arm and the median nerve. In the second part of its course, it is placed upon the flexor profundus and pronator quadratus, lying between the flexor carpi ulnaris and flexor sublimis digitorum. While crossing the annu- lar ligament it is protected from injury by a strong tendinous arch, thrown over it from the pisiform bone ; and in the palm it rests upon the tendons of the flexor sublimis, being covered in by the palmaris 330 ULNAR ARTERY.—BRANCHES. brevis muscle and palmar fascia. It is accompanied in its course by the ven comites, and is in relation with the ulnar nerve for the lower two-thirds of its extent. Plan of the relations of the Ulnar Artery. In Front. Deep fascia, Superficial layer of muscles, Median nerve. In the Hand. Tendinous arch from the pisiform bone, Palmaris brevis muscle, Palmar fascia. Inner Side. Outer Side. Flexor carpi ulnaris, Ulnar Artery. Flexor sublimis digi- Ulnar nerve (lower torum. two-thirds). Behind. Brachialis anticus, Flexor profundus digitorum, Pronator quadratus. In the Hand. Annular ligament, Tendons of the flexor sublimis digitorum. The Branches of the ulnar artery may be arranged like those of the radial into three groups :— Anterior ulnar recurrent, Posterior ulnar recurrent, Fore-arm, Tiicwbianiene ; Anterior interosseous, Posterior interosseous. \ Muscular. Wrist, ; on oe anterior, arpalis posterior. Hand, Digitales. The Anterior ulnar recurrent arises immediately below the elbow, and ascends in front of the joint between the pronator radii teres and brachialis anticus, where it inosculates with the anastomotica magna and inferior profunda. The two recurrent arteries frequently arise by a common trunk. The Posterior ulnar recurrent, larger than the preceding, arises im- mediately below the elbow joint, and passes backwards beneath the origins of the superficial layer of muscles; it then ascends between the two heads of the flexor carpi ulnaris, and beneath the ulnar nerve, and inosculates with the inferior profunda and anastomotica magna. BRANCHES OF THE THORACIC AORTA. 331 The Common interosseous artery is a short trunk which arises from the ulnar, opposite the bicipital tuberosity of the radius. It divides into two branches, the anterior and posterior interosseous arteries. The Anterior interosseous passes down the fore-arm upon the inter- osseous membrane, between the flexor profundus: digitorum and flexor longus pollicis, and, behind the pronator quadratus it pierces that membrane and dosoontte to the back of the wrist, where it inosculates with the posterior carpal branches of the radial and ulnar. It is retained in connection with the interosseous membrane by means of a thin aponeurotic arch. The anterior interosseous artery sends a branch to the median nerve, which it accompanies into the hand. The median artery is sometimes of large size, and occasionally takes the place of the superfi- cial palmar arch. The Posterior interosseous artery passes backwards through an opening between the upper part of the interosseous membrane and the oblique ligament, and is distributed to the muscles on the posterior aspect of the fore-arm. It gives off a recurrent branch, which returns upon the elbow between the anconeus, extensor carpi ulnaris and supinator brevis muscles, and anastomoses with the posterior terminal branches of the superior profunda. The Muscular branches supply the muscles situated along the ulnar - border of the fore-arm. The Carpal branches, anterior and posterior, are distributed to the anterior and posterior aspects of the wrist-joint, where they inosculate with corresponding branches of the radial artery. The Digital branches are given off from the superficial palmar arch, and are four in number. The first and smallest is distributed to the ulnar side of the little finger. The other three are short trunks, which divide between the heads of the metacarpal bones, and form the colla- teral branch of the radial side of the little finger, the collateral branches of the ring and middle fingers, and the collateral branch of the ulnar side of the index finger. The Superficial palmar arch receives the termination of the deep palmar arch from between the abductor minimi digiti and flexor brevis minimi digiti near their origins, and terminates by inosculating with the superficialis vole: upon the ball of the thumb. The communication between the superficial and deep arch is generally described as the communicating branch of the ulnar artery. The mode of distribution of the arteries to the hand is subject to frequent variety. BRANCHES OF THE THORACIC AORTA, Bronchial, (Esophageal, Intercostal. The BRoNCHIAL ARTERIES are four in number, and vary both in 332 BRANCHES OF THE ABDOMINAL AORTA. size and origin. They are distributed to the bronchial glands and tubes, and send branches to the cesophagus, pericardium, and left auricle of the heart. These are the nutritious vessels of the lungs. The CEsopHAGEAL ARTERIES are numerous small branches ; they. arise from the anterior part of the aorta, are distributed to the ceso- phagus, and establish a chain of anastomoses along that tube: the superior inosculate with the bronchial arteries, and with cesophageal branches of the inferior thyroid arteries ; and the inferior with similar branches of the phrenic and gastric-arteries. The INTERCOSTAL, or posterior intercostal arteries, arise from the posterior part of the aorta ; they are nine in number on each side, the two superior spaces being supplied by the superior intercostal artery, a branch of the subclavian. The right intercostals are longer than the left, on account of the position of the aorta. They ascend somewhat obliquely from their origin, and cross the vertebral column behind the thoracic duct, vena azygos major, and sympathetic nerve, to the inter- costal spaces, the left passing beneath the superior intercostal vein, the vena azygos minor and sympathetic. In the intercostal spaces, or rather, upon the external intercostal muscles, each artery gives off a dorsal branch, which passes back between the transverse processes of the vertebrae, lying internally to the middle costo-transverse ligament, and divides into a spinal branch, which supplies the spinal cord and vertebre, and a muscular branch which is distributed to the muscles and integument of the back. The artery then comes into relation with its vein and nerve, the former being above and the latter below, and divides into two branches which run along the borders of conti- guous ribs between the two planes of intercostal muscles, and ana- stomose with the anterior intercostal arteries, branches of the internal mammary. The branch corresponding with the lower border of each rib is the larger of the two. They are protected from pressure during the action of the intercostal muscles, by little tendinous arches thrown across them and attached by each extremity to the bone. BRANCHES OF THE ABDOMINAL AORTA. Phrenic, Gastric, Coeliac axis ~ Hepatic, Splenic. Superior mesenteric, Spermatic, Inferior mesenteric, Supra-renal, Renal, Lumbar, Sacra media. C@LIAC AXIS.—HEPATIC ARTERY. 333 The PHRENIC ARTERIES are given off from the anterior part of the aorta as soon as that trunk has passed through the aortic opening. Passing obliquely outwards upon the under surface of the diaphragm, each artery divides into two branches, an internal branch which runs forwards and inosculates with its fellow of the opposite side in front of the cesophageal opening ; and an eaternal branch which proceeds outwards towards the great circumference of the muscle, and sends branches to the supra-renal capsules. The phrenic arteries inosculate with branches of the internal mammary, inferior intercostal, epigastric, cesophageal, gastric, hepatic, and supra-renal arteries. They are not unfrequently derived from the cceliac axis, or from one of its divisions, and sometimes they give off the supra-renal arteries. The Ca@tac Axis (xaAia, ventriculus) is the first single trunk given off from the abdominal aorta. It arises opposite the upper border of the first lumbar vertebra, is about half an inch in length, and divides into three large branches, gastric, hepatic, and splenic. Relations.—The trunk of the cceliac axis has in relation with it, in Jront the lesser omentum ; on the right side the right semilunar ganglion and lobus Spigelii of the liver; on the left side the left semilunar gan- glion and cardiac portion of the stomach ; and below, the upper border of the pancreas and lesser curve of the stomach. It is completely surrounded by the solar plexus. The Gasrric ARTERY (coronaria ventriculi), the smallest of the three branches of the cceliac axis, ascends between the two layers of the lesser omentum to the cardiac orifice of the stomach, then runs along the lesser curvature to the pylorus, and inosculates with the pyloric branch of the hepatic. It is distributed to the lower extremity of the cesophagus and lesser curve of the stomach, and anastomoses with the cesophageal arteries and vasa brevia of the splenic artery. The Hepatic ARTERY curves forwards, and ascends along the right border of the lesser omentum to the liver, where it divides into two branches (right and left), which enter the transverse fissure, and are distributed along the portal canals to the right and left lobes.* It is in relation in the right border of the lesser omentum, with the ductus communis choledochus and portal vein, and is surrounded by the hepatic plexus of nerves and numerous lymphatics. There are sometimes two hepatic arteries, in which case one is derived from the superior mesenteric artery. : The Branches of the hepatic artery are, the Pyloric, Giatroiaodinatins ; Gastro-epiploica dextra, Pancreatico-duodenalis. Cystic. * For the mode of distribution of the hepatic artery within the liver, see the ** Minute Anatomy ’”’ of that organ in the Chapter on the Viscera. 334 BRANCHES OF THE ABDOMINAL AORTA. Fig. 122.* = = = = = = = = = t 77 ~ Cy T1777; 7, 2 3 on 3 TLL {if Pecearupers cum TTT * The abdominal aorta with its branches. 1. The phrenic arteries. 2. The celiac axis. 3. The gastric artery. 4. The hepatic artery, dividing into the right and left hepatic branches. 5. The splenic artery, passing outwards to the spleen. 6, The supra-renal artery of the right side, 7. The right renal artery, which is longer than the left, passing outwards to the right kidney. 8. The lumbar arteries. 9. The superior mesenteric artery. 10, The two spermatic arteries. 11. The inferior mesenteric artery. 12. The sacra media. 13. Thecommon iliacs. 14. The internal iliac of the right side. 15. The ex- ternal iliac artery. 16. The epigastric artery. 17. The circumflexa ilii artery. 18. The femoral artery. SPLENIC ARTERY.—BRANCHES. 335 The Pyloric branch given off from the hepatic near the pylorus, is distributed to the commencement of the duodenum and to the lesser curve of the stomach, where it inosculates with the gastric artery. The Gastro-duodenalis artery is a short but large trunk, which descends behind the pylorus, and divides into two branches, the gastro-epiploica dextra, and pancreatico-duodenalis. Previously to its division, it gives off some inferior pyloric branches to the small end of the stomach. The Gastro-epiploica dextra runs along the great curve of the stomach lying between the two layers of the great omentum, and inosculates at about its middle with the gastro-epiploica sinistra, a branch of the splenic artery. It supplies the great curve of the sto- mach and the great omentum ; hence the derivation of its name. The Pancreatico-duodenalis curves along the fixed border of the duodenum, partly concealed by the attachment of the pancreas, and is distributed to the pancreas and duodenum. It inosculates inferiorly with the first jejunal, and with the pancreatic branches of the superior mesenteric artery. The Cystic artery, generally a branch. of the right hepatic, is of smali size, and ramifies between the coats of the gall bladder, pre- viously to its distribution to the mucous membrane. The SPLENIC ARTERY, the largest of the three branches of the cceliac axis, passes. horizontally to the left along the upper border of the pancreas, and divides into five or six large branches which enter the hilus of the spleen and are distributed to its structure. In its course it is tortuous and serpentine, and frequently makes a complete turn upon itself. It lies in a narrow groove in the upper border of the pancreas, and is accompanied by the splenic vein, and by the splenic plexus of nerves. The Branches of the splenic artery are the — Pancreatic parve, Pancreatica magna, Vasa brevia, Gastro-epiploica sinistra. The Pancreatice parve are numerous small branches distributed to the pancreas, as the splenic artery runs along its upper border. One of these, larger than the rest, follows the course of the pancreatic duct, and is called pancreatica magna. The Vasa brevia are five or six branches of small size which pass from the extremity of the splenic artery and its terminal branches, between the layers of the gastro-splenic omentum, to the great end of the stomach, to which they are distributed, inosculating with branches of the gastric artery and gastro-epiploica sinistra. The. Gastro-epiploica sinistra appears to be the continuation of the splenic artery ; it passes forwards from left to right, along the great 336 SUPERIOR MESENTERIC ARTERY. curve of the stomach, lying between the layers of the great omentum, and inosculates with the gastro-epiploica dextra. It is distributed to the greater curve of the stomach and to the great omentum. Fig. 123.* The SUPERIOR MESENTERIC ARTERY,the second of the single trunks, and next in size to the ceeliac axis, arises from the aorta immediately below that vessel, and behind the pancreas. It passes forwards between the pancreas and transverse duodenum, and descends within the layers of the mesentery, to the right iliac fossa, where it terminates * The distribution of the branches of the cceliac axis. 1. The liver. 2. Its transverse fissure. 3. The gall bladder. 4. The stomach. 5. The entrance of the cesophagus. 6. The pylorus. 7. The duodenum, its descending por- tion. 8. The transverse portion of the duodenum. 9. The pancreas. 10. The spleen. 11. The aorta, 12. The ceeliac axis. 13. The-gastric artery. 14. The hepatic artery. 15. Its pyloric branch. 16. The gastro-duodenalis. 17. The gastro-epiploica dextra. 18. The pancreatico-duodenalis, inosculating with a branch from the superior mesenteric artery. 19. The division of the hepatic artery into its right and left branches; the right giving off the cystic branch. 20. The ~ sp artery, traced by dotted lines behind the stomach to the spleen. 21. The gastro-epiploica sinistra, inosculating along the great curvature of the stomach with the gastro-epiploica dextra. 22. The pancrea- tica magna. 23. The vasa brevia to the great end of the stomach, inosculating with branches of the gastric artery. 24. The superior mesenteric artery, emerging from between the pancreas and transverse portion of the duodenum. " SUPERIOR MESENTERIC ARTERY. 337 very much diminished in size. It forms a curve in its course, the con- vexity being directed towards the left, and the concavity to the right. It is in relation near its commencement with the portal vein: and is ac- companied by two veins, and the superior mesenteric plexus of nerves. Fig. 124.* ao ta % a i} \, % S, J < y, 2 \s os ac , AN oa i) . = ¢ ‘ y Sk Mw, : TS Al aL XJ WS [= ; ic har SS Sail SA" bs, MeN yy * The course and distribution of the superior mesenteric artery. 1. The descending portion of the duodenum. 2. The transverse portion. 3. The pancreas. 4. The jejunum. 5. The ileum. 6. The cecum, from which the appendix vermiformis is seen projecting. 7. The ascending colon. 8. The transverse colon. 9. The commencement of the descending colon. 10. The superior mesenteric artery. 11. The colica media. 12. The branch which inosculates with the colica sinistra. 13. The branch of the superior mesenteric tico-duodenali 14. The colica artery, which inosculates with the p dextra. 15. The ileo-colica. 16, 16. The branches from the convexity of the superior mesenteric to the small intestines. Z 338 SPERMATIC ARTERIES. The branches of the superior Mesenteric Artery are— Vasa intestini tenuis, Tleo-colica, Colica dextra, Colica media. The Vasa intestini tenuis arise from the convexity of the superior mesenteric artery. They vary from fifteen to twenty in number, and are distributed to the small intestine from the duodenum to the termi- nation of the ileum. In their course between the layers of the mesentery, they form a series of arches by the inosculation of their er branches ; from these are developed secondary arches, and from the latter a third series of arches, from which the branches arise which are distributed to the coats of the intestine. From the middle branches a fourth and sometimes even a fifth series of arches is pro- duced. By means of these arches a direct communication is establish- ed between all the branches given off from the convexity of the superior mesenteric artery; the superior branches moreover supply the pancreas and duodenum, and inosculate with the pancreatico-duodena- lis; and the inferior with the ileo-colica. The Jleo-colic artery is the last branch given off from the concavity of the superior mesenteric. It descends to the right iliac fossa, and divides into branches which communicate and form arches, from which branches are distributed to the termination of the ileum, the caecum, and the commencement of the colon. This artery inosculates on the one hand with the last branches of the vasa intestini tenuis, and on the other with the colica dextra. The Colica dextra arises from about the middle of the concavity of the superior mesenteric, and divides into branches which form arches, and are distributed to the ascending colon. Its descending branches inosculate with the ileo-colica, and the ascending with the colica media. The Colica media arises from the upper part of the concavity of the superior mesenteric, and passes forwards between the layers of the transverse mesocolon, where it forms arches, and is distributed to the transverse colon. It inosculates on the right with the colica dextra; and on the left with the colica sinistra, a branch of the inferior mesen- teric artery. The SpERMATIC ARTERIES are two small vessels which arise from , the front of the aorta below the superior mesenteric ; from this origin each artery passes obliquely outwards, and accompanies the corre- sponding ureter along the front of the psoas muscle to the border of the pelvis, where it is in relation with the external iliac artery. It is then di- rected outwards to the internal abdominal ring, and follows the course of the spermatic cord along the spermatic canal and through the scrotum to the testicle, to which it is distributed. The right spermatic artery INFERIOR MESENTERIC ARTERY- 339 lies in front of the vena cava, and both vessels are accompanied by their corresponding veins and by the spermatic plexuses of nerves. 7 Fig. 125.* SS E oy * The distribution and branches of the inferior mesenteric artery. 1, 1. The superior mesenteric artery, with its branches and the small intestines turned over to the right side. 2. The cecum and appendix ceci. 3. The ascending colon. 4. The transverse colon raised upwards. 5. The descending colon. 6. Its sigmoid flexure. 7. Therectum. 8. The aorta. 9. The inferior mesen- teric artery. 10. The colica sinistra, inosculating with, 11, the colica media, a branch of the sapeioe mesenteric artery. 12, 12. Sigmoid branches. 13. The superior hemorrhoidal artery. 14. The pancreas. 15. The descending portion of the duodenum. 340 © RENAL ARTERIES,—-LUMBAR ARTERIES. The spermatic arteries in the female descend into the pelvis and pass between the two layers of the broad ligaments of the uterus, to be distributed to the ovaries, Fallopian tubes, and round ligaments ; along the latter they are continued to the inguinal canal and labium at.each side. They inosculate with the uterine arteries. The INFERIOR MESENTERIC ARTERY, smaller than the superior, arises from the abdominal aorta, about two inches below the origin of that vessel, and descends between the layers of the left mesocolon, to the left iliac fossa, where it divides into three branches: Colica sinistra, Sigmoidez, Superior hemorrhoidal. The Colica sinistra is distributed to the descending colon, and ascends to inosculate with the colica media. This is the largest arterial in- osulation in the body. The Sigmoidee are several large branches which are distributed to the sigmoid flexure of the descending colon. They form arches, and inosculate above with the colica sinistra, and below with the superior hemorrhoidal artery. The Superior hemorrhoidal artery is the continuation of the inferior mesenteric. It crosses the ureter and common iliac artery of the left side, and descends between the two layers of the meso-rectum as far as the middle of the rectum to which it is distributed, anastomosing with the middle and external hemorrhoidal arteries. The Supra-RENAL are two small, vessels which arise from the aorta immediately above the renal arteries, and are distributed to the supra-renal capsules. They are sometimes branches of the phrenic or of the renal arteries, The RENAL ARTERIES (emulgent) are two large trunks given off from the sides of the aorta immediately below the superior mesenteric artery ; the right is longer than the left on account of the position of the aorta, and passes behind the vena cava to the kidney of that side. The left is somewhat higher than the right. They divide into several large branches previously to entering the kidney, and ramify very minutely in its vascular portion. The renal arteries supply several small branches to the supra-renal capsules. The LumBaR arrerizs correspond with the intercostals in the chest ; they are four or five in number on each side, and curve around the bodies of the lumbar vertebree beneath the psoas muscles, and di- vide into two branches; one of which passes backwards between the transverse processes, and is distributed to the vertebrae and spinal cord EP ah ge wat, — o eee Pe. ee COMMON ILIAC ARTERIES. 341 and to the muscles of the back, whilst the other takes its course be- hind the quadratus lumborum muscle and supplies the abdominal muscles. The first lumbar artery runs along the lower border of the last rib, and the last along the crest of the ilium. In passing between the psoas muscles and the vertebra, they are protected by a series of tendinous arches, which defend them and the communicating branches of the sympathetic nerve from pressure during the action of the muscle. The Sacra MEDIA arises from the posterior part of the aorta at its bifurcation, and descends along the middle of the anterior surface of the sacrum to the first piece of the coccyx where it terminates by in- osculating with the lateral sacral arteries. It distributes branches to the rectum and anterior sacral nerves, and inosculates on either side with the lateral sacral arteries. Varieties in the Branches of the abdominal Aorta.—The phrenic arteries are very rarely both derived from the aorta. One or both may be branches of the cceliac axis ; one may proceed from the gastric artery, from the renal, or from the upper lumbar artery. There are occasionally three or more phrenic arteries. The coeliac axis is very variable in length, and gives off its branches irregularly. There are sometimes two or even three hepatic arteries, one of which may be derived from the gastric or even from the superior mesenteric. The colica media is sometimes derived from the hepatic artery. The spermatic arteries are very variable both in origin and number. The right spermatic may be a branch of the renal artery, and the left a branch of the inferior mesenteric. The supra-renal arteries may be derived from the phrenic or renal arteries. The renal arteries present several varieties in number; there may be three or even four arteries on one side, and one only on the other. When there are several renal arteries on one side, one may arise from the common iliac artery, from the front of the aorta near its lower part, or from the in- ternal iliac. COMMON ILIAC ARTERIES, The abdominal aorta divides opposite the fourth lumbar vertebra into the two common iliac arteries, Sometimes the bifurcation takes place as high as the third, and occasionally as low as the fifth lumbar vertebra. The common iliac arteries are about two inches and a half in length ; they diverge from the termination of the aorta, and pass downwards and outwards on each side to the margin of the pelvis opposite the sacro-iliac symphysis, where they divide into the internal and external iliac arteries. In old persons the common iliac arteries are more or less dilated and curved in their course. The Right common iliac is somewhat longer than the left, and forms a more obtuse angle with the termination of the aorta; the angle of bifurcation is greater in the female than in the male. Relations.—The relations of the two arteries are different on the _ * 342 INTERNAL ILIAC ARTERY. two sides of the body. The right common iliac is in relation in front with the peritoneum, and is crossed at its bifurcation by the ureter. It is in relation posteriorly with the two common iliac veins, and ex- ternally with the psoas magnus. The /e/? is in relation in front with the peritoneum, and is crossed by the rectum and superior hemorrhoi- dal artery, and at its bifurcation by the ureter. It is in relation be- hind with the left common iliac vein, and externally with the psoas magnus. INTERNAL ILIAC ARTERY. The Internal Iliac Artery is a short trunk, varying in length from an inch to two inches. It descends obliquely to a point opposite the upper margin of the great sacro-ischiatic foramen, where it divides into an anterior and a posterior trunk. Fig. 126.* * The distribution and branches of the iliac arteries. 1. The aorta. 2. The left common iliac artery. 3. The external iliac. 4. The epigastric artery. 5. The circumflexa ilii, 6. The internal iliac artery. 7. Its anterior . 8. Its posterior trunk. 9. The umbilical artery giving off (10) the superior vesical artery. After the origin of this branch, the umbilical artery becomes converted into a fibrous cord—the umbilical ligament. 11. The internal pudic artery passing behind the spine of the ischium (12) and lesser sacro-ischiatic ligament. 13. The middle hemorrhoidal artery. 14. The ischiatic artery, also passing behind the anterior sacro-ischiatic ligament to escape from the pelvis. 15. Its inferior vesical branch. 16. The ilio-lumbar, the first branch of the posterior trunk (8) ascending to inosculate with the circumfiexa ilii artery (5) and form an arch along the crest of the ilium. 17. The obturator artery. 18. The lateral sacral. 19. The gluteal artery escaping from the pelvis through the upper part of the great sacro-ischiatic foramen. 20. The sacra media, 21. € right common iliac artery cut short. 22. The femoral artery. Ped Bio, : . Mee’ Ver een i ed, Ve a a " Pe: oe ee ees Ae © | Pe ee eK 4 Se AA VESICAL ARTERIES,—ISCHIATIC ARTERY. 343 Relations.—This artery rests externally upon the sacral plexus and- upon the origin of the pyriformis muscle; posteriorly it is in relation with the internal iliac vein, and anteriorly with the ureter. Branches.—The branches of the anterior trunk are the— Umbilical, Ischiatic, Middle vesical, Internal pudic. Middle hemorrhoidal, And in the female the — Uterine, Vaginal. And of the posterior trunk, the— Tlio-lumbar, Lateral sacral, Obturator, Gluteal. The umbilical artery is the commencement of the fibrous cord into which the umbilical artery of the foetus is converted after birth. In after life, the cord remains pervious for a short distance and constitutes the umbilical artery of the adult, from which the superior vesical artery is given off to the fundus and anterior aspect of the bladder. The cord may be traced forwards by the side of the fundus of the bladder to near its apex, whence it ascends by the side of the linea alba and urachus to the umbilicus. The Middle vesical artery is generally a branch of the umbilical, and sometimes of the internal iliac. It is somewhat larger than the superior vesical, and is distributed to the posterior part of the body of the bladder, the vesicule seminales, and prostate gland. The Middle hemorrhoidal artery is as frequently derived from the ischiatic or internal pudic as from the internal iliac. It is of variable size, and is distributed to the rectum, base of the bladder, vesicule seminales, and prostate gland; and inosculates with the superior and external hemorrhoidal arteries. The Iscu1aTic ARTERY is the larger of the two terminal branches of the anterior division of the internal iliac. It passes downwards between the posterior border of the levator ani, and the pyriformis, resting upon the sacral plexus of nerves and lying behind the internal pudic artery, to the lower border of the great ischiatic notch, where it escapes from the pelvis below the pyriformis muscle. _It then de- scends in the space between the trochanter major and the tuberosity of the ischium in company with the ischiatic nerves, and divides into branches. Its branches within the pelvis are hemorrhoidal which supply the rectum conjointly with the middle hemorrhoidal and sometimes take the place of that artery, and the inferior vesical which is distributed to the base and neck of the bladder, the vesicule seminales, and 344 INTERNAL PUDIC ARTERY. prostate gland. The branches external to the pelvis, are four in number, namely, coccygeal, inferior gluteal, comes nervi ischiatici, and muscular branches. The Coceygeal branch pierces the great sacro-ischiatic ligament, and is distributed to the coccygeus and levator ani muscles, and to the integument around the anus and coccyx. The Inferior gluteal branches supply the gluteus maximus muscle. The Comes nervi ischiatict is a small but regular branch, which ac- companies the great ischiatic nerve to the lower part of the thigh, The Muscular branches supply the muscles of the posterior part of the hip and thigh, and inosculate with the internal and external cir- cumflex arteries, with the obturator, and with the superior perforating artery. The INTERNAL PUDIC ARTERY, the other terminal branch of the anterior trunk of the internal iliac, descends in front of the ischiatic artery to the lower border of the great ischiatic foramen. It emerges from the pelvis through the great sacro-ischiatic foramen below the pyriformis muscle, crosses the spine of the ischium, and re-enters the pelvis through the lesser sacro-ischiatic foramen; it then crosses the internal obturator muscle to the ramus of the ischium, being situated at about an inch from the margin of the tuberosity, and bound down by the obturator fascia; it next ascends the ramus of the ischium, enters between the two layers of the deep perineal fascia lying along the border of the ramus of the os pubis, and at the symphysis pierces the anterior layer of the deep perineal fascia, and very much diminish- ed in size reaches the dorsum of the penis along which it runs, sup- plying that organ under the name of the dorsalis penis. Branches.—The branches of the internal pudic artery within the pelvis are several small ramuscules to the base of the bladder, the vesicule seminales, and the prostate gland; and hemorrhoidal branches which supply the middle of the rectum, and frequently take the place of the middle hemorrhoidal branch of the internal iliac. The branches, external to the pelvis, are the External hemorrhoidal, Superficialis perinei, Transversalis perinei, Arteria bulbosi, Arteria corporis cavernosi, Arteria dorsalis penis. ; The External hemorrhoidal arteries are three or four small branches, given off by the internal pudic while behind the tuberosity of the ischium.’ They are distributed to the anus, and to the muscles, the fascia, and the integument in the anal region of the perineum. The Superficial perineal artery is given off near the attachment of the crus penis; it pierces the connecting layer of the superficial and Ce iar Lacy vy Pola ame INTERNAL PUDIC ARTERY. _ 345 deep perineal fascia, and rans forward across the transversus perinei muscle, and along the groove between the accelerator urine and erector penis to the septum scroti, upon which it ramifies under the name of arteria septi. It distributes branches to the scrotum, and to the perineum in its course forwards. One of the latter, larger than the rest, crosses the perineum, resting on the transversus perinei muscle, and is named the transversalis perinet. The Artery of the bulb is given off from the pudic nearly opposite the opening for the transmission of the urethra; it passes almost trans- versely inwards betwen the two layers of the deep perineal fascia, and pierces the anterior layer to enter the corpus spongiosum at its bulbous extremity. It is distributed to the corpus spongiosum. Fig. 127.* * The arteries of the perineum; on the right side the superficial arteries are seen, and on the left the deep. 1. The penis, consisting of corpus spon- iosum and corpus cavernosum. ‘The crus penis on the left side is cut rough. 2. The acceleratores urinze muscles, enclosing the bulbous portion of the corpus spongiosum. 3. The erector penis, spread out upon the crus penis of the right side. 4. The anus, surrounded by the sphincter ani muscle. 5. The ramus of the ischium and os pubis. 6. The tuberosity of the ischium. 7. The lesser sacro-ischiatic ligament, attached by its small extremity to the spine of the ischium. 8. The coccyx. 9. The internal pudic artery, crossing the spine of the ischium, and entering the perineum. 10. External hemorrhoidal branches. 11. The superficialis perinei artery, giving off a small branch, transversalis perinei, upon the transversus_peri- nei muscle. 12. The same artery on the left side cut off. 13. The artery of the bulb. 14. The two terminal branches of the internal pudic artery; one is seen entering the divided extremity of the crus penis, the artery of the corpus cavernosum; the other, the dorsalis penis, ascends upon the dorsum of the organ. / 346 OBTURATOR ARTERY. The Artery of the corpus cavernosum pierces the crus penis, and runs forward in the interior of the corpus cavernosum, by the side of the septum pectiniforme. It ramifies in the parenchyma of the venous structure of the corpus cavernosum. The Dorsal artery of the penis ascends between the two crura and symphysis pubis to the dorsum penis, and runs forward through the suspensory ligament in the groove of the corpus cavernosum to the glans, distributing branches in its course to the body of the organ and to the integument. The Internal pudic artery in the female is smaller than in the male; its branches, with their distribution, are in principle the same. The superficial perineal artery supplies the analogue of the lateral half of the scrotum, viz. the greater labium. The artery of the bulb supplies the meatus urinarius, and the vestibule; the artery of the corpus cavernosum, the cavernous body of the clitoris, and the arteria dor- salis clitoridis, the dorsum of that organ. The Urerimne and VaGINAL arteries of the female are derived either from the internal iliac, or from the umbilical, internal pudic, or ischiatic arteries. The former are very tortuous in their course, and ascend between the layers of the broad ligament, to be distributed to the uterus. The latter ramify upon the exterior of the vagina, and supply its mucous membrane. Branches of the posterior trunk. The Ilio-lumbar artery ascends beneath the external iliac vessels and psoas muscle, to the posterior part of the crest of the ilium, where it divides into two branches, a lumbar branch which supplies the psoas and iliacus muscles, and sends a ramuscule through the fifth interver- tebral foramen to the spinal cord and its membranes; and an iliac branch which passes along the crest of the ilium distributing branches to the iliacus and abdominal muscles, and inosculating with the lumbar and gluteal arteries, and with the circumflexa ilii. The OsrurRATOR ARTERY is exceedingly variable in point of origin; it generally proceeds from the posterior trunk of the internal iliac artery, and passes forwards a little below the brim of the pelvis to the upper border of the obturator foramen. It there escapes from the pelvis through a tendinous arch formed by the obturator mem- brane, and divides into two branches; an internal branch which curves inwards around the bony margin of the obturator foramen, between the obturator externus muscle and the ramus of the ischium, and distri- butes branches to the obturator muscles, the pectineus, the adductor muscles, and to the organs of generation, and inosculates with the inter- nal circumflex artery. And an eaternal branch which pursues its course along the outer margin of the obturator foramen to the space between the gemellus inferior and quadratus femoris, where it inosculates with GLUTEAL ARTERY. 347 the ischiatic artery. In its course backwards it anastomoses with the internal circumflex, and sends a branch through the notch in the acetabulum to the hip-joint. Within the pelvis the obturator artery gives off a branch to the iliacus muscle, and a small ramuscule which inosculates with the epigastric artery. The LATERAL SACRAL ARTERIES are generally two in number on each side; superior and inferior. The superior passes inwards to the first sacral foramen and is distributed to the contents of the spinal canal, from which it escapes by the posterior sacral foramen, and supplies the integument on the dorsum of the sacrum. The infe- rior passes down by the side of the anterior sacral foramina to the coccyx; it first pierces and then rests upon the origin of the pyriformis, and sends branches into the sacral canal to supply the sacral nerves. Both arteries inosculate with each other and with the sacra media. The GLUTEAL ARTERY is the continuation of the posterior trunk of the internal iliac: it passes backwards between the lumbo-sacral and first lumbar nerve through the upper part of the great sacro- ischiatic foramen, and above the pyriformis muscle, and divides into three branches, superficial, deep superior, and deep inferior. _ The Superficial branch is directed forwards, between the gluteus maximus and medius, and divides into numerous branches, which are distributed to the upper part of the gluteus maximus and to the inte- gument of the gluteal region. The Deep superior branch passes along the superior curved line of the ilium, between the gluteus medius and minimus to the anterior superior spinous process, where it inosculates with the superficial cir- cumflexa ilii and external circumflex artery. There are frequently two arteries which follow this course. The Deep inferior branches are several large arteries which cross the gluteus minimus obliquely to the trochanter major, where they inosculate with branches of the external circumflex artery, and send branches through the gluteus minimus to supply the capsule of the hip-joint. . Varieties in the Branches of the internal iliac.—The most important of the varieties occurring among these branches is the origin of the dorsal artery of the penis from the internal iliac or ischiatic. The artery in this case passes forwards by the side of the prostate gland, and through the upper part of the deep perineal fascia. It would be endangered in the operation of lithotomy. The dorsal artery of the penis is sometimes derived from the obturator, and sometimes from one of the external pudic arteries. The artery of the bulb, in its normal course, passes almost transversely inwards to the corpus spongiosum. Occasionally, however, it is so oblique in its direction as to render its division in lithotomy unavoidable. The obturator artery may be very small or altogether wanting, its place being supplied by a branch from the external iliac or epigastric. 348 EXTERNAL ILIAC ARTERY. The external iliac artery of each side passes obliquely downwards along the inner border of the psoas muscle, from opposite the sacro- iliac symphysis to the femoral arch, where it becomes the femoral Relations, —It is in relation in front with the spermatic vessels, the peritoneum, and a thin layer of fascia, derived from the iliac fascia, which surrounds the artery and vein. At its commencement it is crossed by the ureter, and near its termination by the crural branch of the genito-crural nerve and the circumflexa ilii vein. Haternally it lies against the psoas muscle, from which it is separated by the iliac fascia; and posteriorly it is in relation with the external iliac vein, which, at the femoral arch, becomes placed to its inner side. The artery is surrounded throughout the whole of its course by lymphatic vessels and glands. Branches.—Besides several small branches which supply the glands surrounding the artery, the external iliac gives off two branches, the— Epigastric, Circumflexa ilii. The Epigastric artery arises from the external iliac near Poupart’s ligament; and passing forwards between the peritoneum and transver- salis fascia, ascends obliquely to the border of the sheath of the rectus. It enters the sheath near its lower third, passes upwards behind the rectus muscle, to which it is distributed, and in the substance of that muscle inosculates near the ensiform cartilage with the termination of the internal mammary artery. It lies internally to the internal abdominal ring and immediately above the femoral ring, and is crossed near its origin by the vas deferens in the male, and by the round liga- ment in the female. The only branches of the epigastric artery worthy of distinct notice are the Cremasteric, which accompanies the spermatic cord and sup- plies the cremaster muscle ; and the ramusculus which inosculates with the obturator artery. The Epigastric artery forms a prominence of the peritoneum which divides the iliac fossa into an internal and an external portion ; it is from the former that direct inguinal hernia issues, and from the latter, oblique inguinal hernia. The Circumflexa ilit arises from the outer side of the external iliac, nearly opposite the epigastric artery. It ascends obliquely along Poupart’s ligament, and curving around the crest of the ilium between the attachments of the internal oblique and transversalis muscle, inos- culates with the ilio-lumbar and inferior lumbar artery. Opposite the anterior superior spinous process of the ilium, it gives off a large ascending branch which passes upwards between the internal oblique and transyersalis, and divides into numerous branches which supply FEMORAL ARTERY. 349 the abdominal muscles, and inosculate with the inferior intercostal and with the lumbar arteries. Varieties in the branches of the external iliac._—The epigastric artery not unfrequently * gives off the obturator, which descends in contact with the external iliac vein, to the obturator foramen. In this situa- tion the artery would lie to the outer side of the femoral ring, and would not be endangered in the operation for dividing the stricture of femoral hernia. But occasionally the obturator passes along the free margin of Gimbernat’s ligament in its course to the obturator foramen, and would completely encircle the neck of the hernial sac ; a position in which it could scarcely escape the knife of the operator. In a preparation in my anatomical collection the branch of communication between the epigastric and obturator arteries is very much enlarged, and takes this dangerous course. FEMORAL ARTERY. Emerging from beneath Poupart’s ligament, the external iliac artery enters the thigh and becomes the femoral. The femoral artery passes down the inner side of the thigh, from Poupart’s ligament, at a point midway between the anterior superior spinous process of the ilium and the symphysis pubis, to the opening in the adductor magnus, at the junction of the middle with the inferior third of the thigh, where it becomes the popliteal artery. The femoral artery and vein are enclosed in a strong sheath, femo- ral or crural canal, which is formed for the greater part of its extent by aponeurotic and areolar tissue, and by a process of fascia sent inwards from the fascia lata. Near Poupart’s ligament this sheath is much larger than the vessels it contains, and is continuous with the fascia transversalis, and iliac fascia. If the sheath be opened at this point, the artery will be seen to be situated in contact with the outer wall of the sheath. The vein lies next the artery, being separated from it by a fibrous septum, and between the vein and the inner wall of the sheath, and divided from the vein by another thin fibrous septum, is a triangular interval, into which the sac is protruded in femoral hernia. This space is occupied in the normal state of the parts. by loose areolar tissue, and by lymphatic vessels which pierce the inner wall of the sheath to make their way to a gland, situated in the femoral ring. Relations.—The upper third of the femoral artery is superficial, being covered only by the integument, inguinal glands, and by the * The proportion in which high division of the obturator artery from the epigastric occurs, is stated to be one inthree. In two hundred and fifty subjects examined by Cloquet with a view to ascertain how frequently the high division took place, he found the obturator arising from the epigastric on both sides one hundred and fifty times; on one side twenty-eight times, and six times it arose from the femoral artery. 350 . FEMORAL ARTERY Fig. 128.* * A view of the anterior and inner aspect of the thigh, showing the course and branches of the femoral artery. 1. The lower part of the aponeurosis of the external oblique muscle; its inferior margin is Poupart’s ligament. 2. The external abdominal ring. 3, 3. The upper and lower part of the sartorius muscle; its middle portion having been removed. 4. The rectus. 5. The vastus internus. 6. The patella. 7. The iliacus and psoas; the latter being nearest the artery. 8. The pectineus. 9. The adductor longus. 10. The ten- dinous canal for the femoral artery formed by the adductor magnus, and vastus FEMORAL ARTERY. 351 superficial and deep fascie. The lower two-thirds are covered by the sartorius muscle. To its outer side the artery is first in relation with the psoas and iliacus, and then with the vastus internus. Behind it rests upon the inner border of the psoas muscle ; it is next separated from the pectineus by the femoral vein, profunda vein and artery, and then lies on the adductor longus to its termination: near the lower border of the adductor longus, it is placed in an aponeurotic canal, formed by an arch of tendinous fibres, thrown from the border of the adductor longus and the border of the opening in the adductor magnus, to the side of the vastus internus. To its inner side it is in relation at its upper part with the femoral vein, and lower down with the pectineus, adductor longus, and sartorius. The immediate relations of the artery are the femoral vein, and two saphenous nerves. The vein at Poupart’s ligament lies to the inner side of the artery ; hut lower down gets altogether behind it, and inclines to its outer side. The short saphenous nerve lies to the outer side, and somewhat upon the sheath for the lower two-thirds of its extent; and the long saphenous nerve is situated within the sheath, and in front of the artery for the same extent. Plan of the Relations of the Femoral Artery. Front. Fascia lata, Saphenous nerves, Sartorius, Arch of the tendinous canal. Inner Side. Outer Side. Femoral vein, Psoas, Pectineus, Femoral artery. fliacus, Adductor longus, Vastus internus. Sartorius. Behind. Psoas muscle, Femoral vein, Adductor longus. internus muscles. 11. The adductor magnus. 12. The gracilis. 13. The ten- don of the semi-tendinosus. 14. The femoral artery. 15. The superficial cir- cumflexa ilii artery taking its course along the line of Poupart’s ligament, to the crest of theilium. 2. The superficial epigastric artery. 16. The two external pudic arteries, superficial and deep. 17. The profunda artery, giving off 18, its external circumflex branch; and lower down the three perforantes. A small bend of the internal circumflex artery (8) is seen behind the inner margin of the femoral, just below the deep external pudie artery. 19. The anastomotica magna, descending to the knee, upon which it ramifies (6). 352 PROFUNDA ARTERY. Branches.—The branches of the Femoral Artery are the — Superficial circumflexa ilii, Superficial epigastric, Superficial external pudic, Deep external pudic, External circumflex, Profunda < Internal circumflex, 1 en perforating. Muscular, Anastomotica magna. The Superficial circumflexa ilii artery arises from the femoral, imme- diately below Poupart’s ligament, pierces the fascia lata, and passes obliquely outwards towards the crest of the ilium. It supplies the integument of the groin, the superficial fascia, and inguinal glands. The Superficial epigastric arises from the femoral, immediately below Poupart’s ligament, pierces the fascia lata, and ascends ob- liquely towards the umbilicus between the two layers of superficial fascia. It distributes branches to the inguinal glands and integument, and inosculates with branches of the deep epigastric and internal mammary artery. The Superficial eaternal pudic arises near the superficial epigas- tric artery ; it pierces the fascia lata, at the saphenous opening, and passes transversely inwards crossing the spermatic cord, to be distri- buted to the integument of the penis and scrotum in the male, and to the labia in the female. The Deep external pudic arises from the femoral, a little lower down than the preceding: it crosses the femoral vein immediately below the termination of the internal saphenous vein, and piercing the pubic portion of the fascia lata passes beneath that fascia to the inner border of the thigh, where it again pierces the fascia ; having become superficial, it is distributed to the integument of the scrotum and perineum. : The PRoruNDA FEMORIS arises from the femoral artery at two inches below Poupart’s ligament: it passes downwards and backwards and a little outwards, behind the adductor longus muscle, pierces the adductor magnus, and is distributed to the flexor muscles on the pos- terior part of the thigh. Relations.—In its course downwards it rests successively upon the pectineus, the conjoined tendon of the psoas and iliacus, adductor brevis, and adductor magnus muscles. To its outer side the tendinous insertion of the vastus internus muscle intervenes between it and the femur ; on its inner side it is in relation with the pectineus, adductor brevis and adductor magnus; and iz front it is separated from the fe- moral artery, above by the profunda vein and femoral vein, and below by the adductor longus muscle. Fer ee One ee ee ee ee ee PROFUNDA ARTERY. 353 Plan of the relations of the Profunda apt In Front, Profunda vein, - Adductor longus. Inner Side. Outer Side. Pectineus, Profunda artery. Psoas and Iliacus, Adductor brevis, Vastus internus, Adductor magnus. Femur. Behind. Pectineus Tendon of psoas and iliacus, Adductor brevis, Adductor magnus. : Branches.—The branches of the profunda artery are the external circumflex, internal circumflex, and three perforating arteries. The Eaternal circumflex artery passes obliquely outwards between the divisions of the crural nerve, then between the rectus and crureus muscle, and divides into three branches; ascending, which inosculates with the terminal branches of the gluteal artery ; descending, which ' inosculates with the superior external articular artery; and middle, which continues the original course of the artery around the thigh, and anastomoses with branches of the ischiatic, internal circumflex, and superior perforating artery. It supplies the muscles on the ante- rior and outer side of the thigh. The Internal circumflex artery is larger than the external ; it winds around the inner side of the neck of the femur, passing between the pectineus and psoas, and along the border of the external obturator muscle, to the space between the quadratus femoris and upper border of the adductor magnus, where it anastomoses with the ischiatic, ex- ternal circumflex, and superior perforating artery. It supplies the muscles on the upper and inner side of the thigh, anastomosing with the obturator artery, and sends a small branch through the notch in the acetabulum into the hip-joint. The Superior perforating artery passes backwards between the pec- tineus and adductor brevis, pierces the adductor magnus near the femur, and is distributed to the posterior muscles of the thigh; inos- culating freely with the circumflex and ischiatic arteries, and with the branches of the middle perforating artery. The Middle perforating artery pierces the tendons of the adductor brevis and magnus, and is distributed like the superior ; inosculating with the superior and inferior perforantes. This branch frequently gives off the nutritious artery of the femur. The Inferior perforating artery is given off below the adductor brevis, and pierces the tendon of the adductor magnus, supplying it and the flexor muscles, and inosculating with the middle perforating 24 354 POPLITEAL ARTERY. artery above, and with the articular branches of the popliteal below. It is through the medium of these branches that the collateral circula- tion is maintained in the limb after ligature of the femoral artery. The Muscular branches are given off by the femoral artery through- out the whole of its course. They supply the muscles in immediate proximity with the artery, particularly those of the anterior aspect of the thigh. One of these branches, larger than the rest, arises from the femoral immediately below the origin of the profunda, and passing outwards between the rectus and sartorius divides into branches which are distributed to all the muscles of the anterior aspect of the thigh. This may be named the superior muscular artery. The Anastomotica magna arises from the femoral while in the ten- dinous canal formed by the adductors and vastus internus. It runs along the tendon of the adductor magnus to the jnner condyle, and inosculates with the superior internal articular artery: some of its branches are distributed to the vastus internus muscle and to the crureus, and terminate by anastomosing with the branches of the ex- ternal circumflex and superior external articular artery. POPLITEAL ARTERY. The popliteal artery commences from the termination of the femoral at the opening in the adductor magnus muscle, and passes obliquely outwards through the middle of the popliteal space to the lower border of the popliteus muscle, where it divides into the anterior and posterior tibial artery. Relations—In its course downwards it rests first on the femur, then on the posterior ligament of the knee-joint, then on the fascia, covering the popliteus muscle. Superficially it is in relation with the semi-membranosus muscle, next with a quantity of fat which separates it from the deep fascia, and near its termination with the gastrocne- mius, plantaris, and soleus ; superficial and external to it is the popli- teal vein, and still more superficial and external, the popliteal nerve. By its inner side it is in relation with the semi-membranosus, internal condyle of the femur, and inner head of the gastrocnemius ; and by its outer side with the biceps, external condyle of the femur, the outer head of the gastrocnemius, the plantaris and the soleus. ee ee ee eT ee * R ANTERIOR TIBIAL ARTERY. 355 Plan of the relations of the Popliteal Artery. Superficially. Semi-membranosus, _Popliteal nerve, Popliteal vein, Gastrocnemius, Plantaris, Soleus. Inner Side. Outer Side. Semi b % Biceps, Internal condyle, Popliteal artery. External condyle, Gastrocnemius. Gastrocnemius, Plantaris, Soleus. Deeply. Femur, a Ligamentum posticum Winslowii Popliteal fascia. ; Branches.—The branches of the popliteal artery are the Superior external articular, Superior internal articular, Azygos articular, Inferior external articular, Inferior internal articular, . Sural. The Superior articular arteries, eaternal and internal, wind around the femur immediately above the condyles, to the front of the knee- joint,’ anastomosing with each other, with the external circumflex, the anastomotica magna, the inferior articular, and the recurrent of the anterior tibial. The external passes beneath the tendon of the biceps, and the internal through an arched opening beneath the tendon of the adductor magnus. They supply the knee-joint and the lower part of the femur. The Azygos articular artery pierces the posterior ligament of the joint, the ligamentum posticum Winslowii, and supplies the synovial membrane in its interior. There are frequently several posterior arti- cular arteries. The Inferior articular arteries wind around the head of the tibia immediately below the joint, and anastomose with each other, the superior articular arteries, and the recurrent of the anterior tibial. The external passes beneath the two external lateral ligaments of the joint, and the internal beneath the internal lateral ligament. They supply the knee-joint and the heads of the tibia and fibula. The Sural arteries (sura, the calf) are two large muscular branches, which are distributed to the two heads of the gastrocnemius muscle. ANTERIOR TIBIAL ARTERY, The anterior tibial artery passes forwards between the two heads of the tibialis posticus muscle, and through the opening in the upper 356 ANTERIOR TIBIAL ARTERY. Fig. 129.* * The anterior aspect of the leg and foot, showing the anterior tibial and dorsalis pedis arteries, with their branches. 1. The tendon of insertion of the quisieeys extensor muscle. 2. The insertion of the ligamentum patellez into the lower border of the patella. 3. The tibia. 4. The extensor proprius pollicis muscle. 5. The extensor longus digitorum. 6. The peronei muscles. 7. The inner belly of the gastrocnemius antl the soleus. 8. The annular ligament be- neath which the extensor tendons and the anterior tibial artery pass into the dorsum of the foot. 9. The anterior tibial artery. 10. Its recurrent branch inosculating with (2) the inferior articular, and (1) the superior articular arteries, ee Pee a LN as eureer er ANTERIOR TIBIAL ARTERY, 357 part of the interosseous membrane, to the anterior tibial region. It then runs down the anterior aspect of the leg to the ankle-joint, where it becomes the dorsalis pedis. ions.—In its course downwards it rests upon the interosseous membrane (to which it is connected by a little tendinous arch which is thrown across it), the lower part of the tibia, and the anterior ligament of the joint. In the upper third of its course it is situated between the tibialis anticus and extensor longus digitorum, lower down between the tibialis anticus and extensor proprius pollicis; and just before it reaches the ankle it is crossed by the tendon of the extensor proprius pollicis, and becomes placed between that tendon and the tendons of the extensor longus digitorum. Its immediate relations are the venz comites and the anterior tibial nerve, which latter lies at first to its outer side, and at about the middle of the leg becomes placed superfici- ally to the artery. Plan of the relations of the Anterior Tibial Artery. Front, Deep fascia, Tibialis anticus, Extensor longus digitorum, Extensor proprius pollicis, Anterior tibial nerve. Inner Side. Outer Side. Tibialis anticus, Anterior tibial Anterior tibial nerve, Tendon of the artery. Extensor longus digitorum, extensor pro- Extensor pro a pollicis, prius pollicis. —— of the extensor ongus digitorum. Behind. Interosseous membrane, Tibia (lower fourth), Ankle joint. Branches —The branches of the Anterior Tibial Artery are the— Recurrent, Muscular, External malleolar, Internal malleolar. The Recurrent branch passes upwards beneath the origin of the tibialis anticus muscle to the front of the knee-joint, upon which it is distributed, anastomosing with the articular arteries. The Muscular branches are very numerous, they supply the muscles of the anterior tibial region. The Malleolar arteries are distributed to the ankle-joint; the ex- ternal passing beneath the tendons of the extensor longus digitorum branches of the popliteal. 11. The internal stthiline artery. 17. The external malleolar inosculating with the anterior peroneal artery 12. 13. The dorsalis pedis artery. 14. The tarsea and metatarsea arteries; the tarsea is nearest the ankle, the metatarsea is seen giving off the interosseze, 15. The dorsalis hallucis artery. 16. The communicating branch. 358 “DORSALIS PEDIS ARTERY. and peroneus tertius, inosculates with the anterior peroneal artery and with the branches of the dorsalis pedis; the ixternal, beneath the tendons of the extensor proprius pollicis and tibialis anticus, inoscu- lates with branches of the posterior tibial and internal plantar artery. They supply branches to the ankle-joint. The DorsaLis PEDIS ARTERY is continued forward along the tibial side of the dorsum of the foot, from the ankle to the base of the meta- tarsal bone of the great toe, where it divides into two branches, the dorsalis hallucis and communicating. Relations.—The dorsalis pedis is situated along the outer border of the tendon of the extensor proprius pollicis; on its fibular side is the innermost tendon of the extensor longus digitorum, and near its termination it is crossed by the inner tendon of the extensor brevis digitorum. It is accompanied by venz comites, and has the continua- tion of the anterior tibial nerve to its outer side. Plan of the relations of the Dorsalis Pedis Artery. In Front. Integument, Deep fascia, Inner tendon of the extensor brevis digitorum. Inner Side. | Outer Side. Tendon of the ex- Dorsalis Pedis Tendon of the extensor tensor proprius Artery. longus digitorum, pollicis, Border of the extensor brevis digitorum muscle. Behind. Bones of the tarsus, with their ligaments. Branches.—The branches of this artery are the— Tarsea, Metatarsea,—interossez, Dorsalis hallucis,—collateral digital, Communicating. The Tarsea arches transversely across the tarsus, beneath the ex- tensor brevis digitorum muscle, and supplies the articulations of the tarsal bones and the outer side of the foot; it anastomoses with the external malleolar, the peroneal arteries, and the external plantar. The Metatarsea forms an arch across the base of the metatarsal bones, and supplies the outer side of the foot, anastomosing with the tarsea and with the external plantar artery. The metatarsea gives off three branches, the interossee, which pass forward upon the dorsal interossei muscles, and divide into two collateral branches for adjoining toes, At their commencement these interosseous branches receive the posterior perforating arteries from the plantar arch, and opposite the heads of the metatarsal bones they are joined by the anterior perforat- ing branches from the digital arteries. ee te ee a POSTERIOR TIBIAL ARTERY. 859 The Dorsalis hallucts runs forward upon the first dorsal interosse- ous muscle, and at the base of the first phalanx divides into two branches, one of which passes inwards beneath the tendon of the ex- tensor proprius pollicis, and is distributed to the inner border of the great toe, while the other bifurcates for the supply of the adjacent sides of the great and second toes. The Communicating artery passes 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. Besides the preceding, numerous branches are distributed to the bones and articulations of the foot, particularly along the inner border of the latter. POSTERIOR TIBIAL ARTERY. The posterior tibial artery passes obliquely downwards along the tibial side of the leg from the lower border of the popliteus muscle to the concavity of the os calcis, where it divides into the internal and external plantar artery. Relations.—In its course downwards it lies first upon the tibialis posticus, next upon the flexor longus digitorum, and then upon the tibia; it is covered in by the intermuscular fascia which separates it above from the soleus, and below from the deep fascia of the leg and the integument. It is accompanied by its venz comites, and by the posterior tibial nerve, which latter lies at first to its outer side, then superficially to it, and again to its outer side. Plan of the relations of the Posterior Tibial Artery. Superficially. Soleus, Deep fascia, The intermuscular fascia. Inner Side. y aie Outer Side. : Posterior Tibial sa eBea Vein. Artery. Posterior tibial nerve, Vein. Deeply. Tibialis posticus, Flexor longus digitorum, Tibia. Branches—The branches of the posterior tibial artery are the— Peroneal, Nutritious, Muscular, Internal calcanean, Internal plantar, External plantar. 360 POSTERIOR TIBIAL ARTERY:> Fig. 130.* * A posterior view of the leg, showing the popliteal and posterior tibial artery. 1. The tendons forming the inner hamstring. 2. The tendon of the biceps forming the outer hamstring. 3. The popliteus muscle. 4. The flexor longus digitorum. 5. The tibialis posticus. 6, The fibula; immediately below the figure is the origin of the flexor longus pollicis; the muscle has been removed in order to expose the peroneal artery. 7. The peronei muscles, longus and brevis. 8. The lower part of the flexor longus pollicis muscle with its tendon. 9. The popliteal artery giving off its articular and muscular branches ; the two superior articular are seen in the upper part of the popliteal space passing above the two heads of the gastrocnemius muscle, which are cut through near PERONEAL ARTERY, 361 The Peroneal artery is given off from the posterior tibial at about two inches below the lower border of the popliteus muscle; it is nearly as large as the anterior tibial artery, and passes obliquely out- wards to the fibula. It then runs downwards along the inner border of the fibula to its lower third, where it divides into the anterior and posterior peroneal artery. Relations.—The peroneal artery rests upon theetibialis posticus muscle, and is covered in by the soleus, the intermuscular fascia, and the flexor longus pollicis, having the fibula to its outer side. Plan of the relations of the Peroneal Artery. In Front. ; Soleus, Intermuscular fascia, Flexor longus pollicis. Outer Side. Peroneal Artery. Fibula Behind. Tibialis posticus. Branches.—The branches of the peroneal artery are muscular to the neighbouring muscles, particularly to the soleus, and the two terminal branches anterior and posterior peroneal. The Anterior peroneal pierces the interosseous membrane at the lower third of the leg, and is distributed on the front of the outer malleolus, anastomosing with the external malleolar and tarsal artery. This branch is very variable in size. The Posterior peroneal continues onwards along the posterior aspect of the outer malleolus to the side of the os calcis, to which and to the muscles arising from it, it distributes eaternal calcanean branches. It anastomoses with the anterior peroneal, tarsal, external plantar, and posterior tibial artery. The Nutritious artery of the tibia arises from the trunk of the tibial, frequently above the origin of the peroneal, and proceeds to the nutritious canal which it traverses obliquely from below upwards. The Muscular branches of the posterior tibial artery are distributed to the soleus and to the deep muscles on the posterior aspect of the leg. One of these branches is deserving of notice, a recurrent branch, which arises from the posterior tibial above the origin of the peroneal their origin. The two inferior are in relation with the popliteus muscle. 10. The anterior tibial artery passing through the angular interspace between the two heads of the tibialis posticus muscle. 11. The posterior tibial artery. 12. The relative position of the tendons and artery at the inner ankle from within outwards, previously to their passing beneath the internal annular liga- ment. 13, The peroneal artery, dividing into two branches; the anterior pe- roneal is seen piercing the interosseous membrane. 14. The posterior peroneal. 362 PLANTAR ARTERIES. artery, pierces the soleus and is distributed upon the inner sidé of the head of the tibia, anastomosing with the inferior internal articular. The Internal calcanean branches, three or four in number, proceed from the posterior tibial artery immediately before its division ; they are distributed to the inner side of the os calcis, to the integument, and to the muscles which arise from its inner tuberosity, and they anasto- mose with the external calcanean branches, and with all the neigh- bouring arteries. PLANTAR ARTERIES. The Internal plantar artery proceeds from the bifurcation of the posterior tibial at the inner malleolus and passes along the inner Fig. 131.* * The arteries of the sole of the foot ; the first and a part of the second layer of muscles having been removed. 1. The under and posterior part of the os calcis ; to which the origins of the first layer of muscles remain attached. 2. he musculus accessorius. 3. The long flexor tendons. 4. The tendon of the peroneus longus. 5. The termination of the posterior tibial artery. 6. The internal plantar. 7. The external plantar artery. 8. The plantar arch giving off four digital branches, which pass forwards on the interossei muscles to divide into collateral branches. Top es 2 VARIETIES IN THE ARTERIES OF THE LOWER EXTREMITY. 363 border of the foot between the abductor pollicis and flexor brevis digitorum muscles, supplying the inner border of the foot and great toe. The External plantar artery, much larger than the internal, passes obliquely outwards between the first and second layers of the plantar muscles, to the fifth metatarsal space. It then turns horizontally in- wards between the second and third layers, to the first metatarsal space, where it inosculates with the communicating branch from the dorsalis pedis. The horizontal portion of the artery describes a slight curve, having the convexity forwards; this is the plantar arch. Branches.—The branches of the external plantar artery are the— Muscular, Articular, Digital,—anterior perforating, Posterior perforating. “ _ Muscular branches are distributed to the muscles in the sole of e foot. The Articular branches supply the ligaments of the articulations of the tarsus, and their synovial membranes. The Digital branches are four in number:—the first is distributed to the outer side of the little toe; the three others pass forwards to the cleft between the toes and divide into collateral branches, which sup- ply the adjacent sides of the three external toes, and the outer side of the second. At the bifurcation of the toes, a small branch is sent upwards from each digital artery, to inosculate with the interosse- ous branches of the metatarsea; these are the anterior perforating arteries. The Posterior perforating are three small branches which pass upwards between the heads of the three external dorsal interossei muscles to inosculate with the arch formed by the metatarsea artery. Varieties in the Arteries of the lower Extremity—The femoral artery occasionally divides at Poupart’s ligament into two branches, and sometimes into three; the former is an instance of the high division of the profunda artery ; and in a case of the latter kind which occurred during my dissections, the branches were the profunda, the superficial femoral, and internal circumflex artery. Dr. Quain, in his “ Elements of Anatomy,” records an instance of a high division of the femoral artery, in which the two vessels became again united in the popliteal region. The point of origin of the profunda artery varies considerably in different subjects, being sometimes nearer to and some- times farther from Poupart’s ligament, but more frequently the former. The branches of the popliteal artery are very liable to variety in size ; and in all these cases the compensating principle, so constant in the vascular system, is strikingly manifested. When the anterior tibial is of small size, the peroneal is large ; and, in place of dividing into two 364 PULMONARY ARTERY. terminal branches at the lower third of the leg, descends to the lower part of the interosseous membrane, and emerges upon the front of the ankle, to supply the dorsum of the foot: or the posterior tibial and plantar arteries are large, and the external plantar is continued be- tween the heads of the first dorsal interosseous muscle, to be distri- buted to the dorsal surface of the foot. Sometimes the posterior tibial artery is small and thread-like; and the peroneal, after descending to the ankle, curves inwards to the inner malleolus, and divides into the two plantar arteries. If in this case the posterior tibial be suffi- ciently large to reach the ankle, it inosculates with the peroneal pre- viously to its division. The internal plantar artery sometimes takes the distribution of the external plantar, which is short and diminutive, and the latter not unfrequently replaces a deficient dorsalis pedis. The varieties of arteries are interesting in the practical application of a knowledge of their principal forms to surgical operations ; in their transcendental anatomy, as illustrating the normal distribution in animals; or in many cases, as diverticula permitted by Nature, to teach her observers two important principles:—/irst, in respect to herself, that, however in her means she may indulge in change, the end is never overlooked, and a limb is as surely supplied by a leash of arteries, various in their course, as by those which we are pleased to consider normal in distribution; and secondly, with regard to us, that we should ever be keenly alive to what is passing beneath our observation, and ever ready in the most serious operation to deviate from our course and avoid—or give eyes to our knife, that it -may see —the concealed dangers which it is our pride to be able to contend with and vanquish. PULMONARY ARTERY, The pulmonary artery arises from the left side of the base of the right ventricle in front of the origin of the aorta, and ascends obliquely to the under surface of the arch of the aorta, where it divides into the right and left pulmonary arteries. In its course upwards and back- wards it inclines to the left side, crossing the commencement of the aorta, and is connected to the under surface of the arch by a ligament- ous cord, the remains of the ductus arteriosus. Relations.—It is enclosed for one half of its extent by the pericar- dium, and receives the attachment of the fibrous portion of the peri- cardium by its upper portion. Behind, it rests against the ascending aorta ; on either side is the appendix of the corresponding auricle with a coronary artery; and above, the cardiac ganglion and the remains of the ductus arteriosus. The Right pulmonary artery passes beneath the arch and behind the ascending aorta, and in the root of the lungs divides into three branches for the three lobes. The Left pulmonary artery, rather larger than the right, passes in front of the descending aorta, to the root of the left lung to which it 4-3. i PULMONARY ARTERY. 365 is distributed. These arteries divide and subdivide in the structure of the lungs, and terminate in capillary vessels which form a network around the bronchial cells, and become continuous with the radicles of the pulmonary veins. Relations.—In the root of the right lung examined from above downwards, the pulmonary artery is situated between the bronchus, and pulmonary veins ; the former being above, the latter below ; while in the left lung the artery is the highest, next the bronchus, and then the veins. On both sides, from before backwards, the artery is situ- ated between the veins and bronchi, the former being in front, and the latter behind. 366 CHAPTER VI. OF THE VEINS. THE veins are the vessels which return the blood to the auricles of the heart, after it has been circulated by the arteries through the va- rious tissues of the body. They are much thinner in structure than the arteries, so that when emptied of their blood they become flat- tened and collapsed. The veins of the systemic circulation convey the dark-coloured and impure or venous blood from the capillary system to the right auricle of the heart, and they are found after death to be more or less distended with that fluid. The veins of the pulmonary circulation resemble the arteries of the systemic circulation in contain- ing during life the pure or arterial blood, which they transmit from the capillaries of the lungs to the left auricle. The veins commence by minute radicles in the capillaries which are everywhere distributed through the textures of the body, and con- verge to constitute larger and larger branches, till they terminate in the large trunks which convey the venous blood directly to the heart. In diameter they are larger than the arteries, and like those vessels their combined arez would constitute an imaginary cone, whereof the apex is placed at the heart, and the base at the surface of the body. It follows from this arrangement, that the blood in returning to the heart is passing from a larger into a smaller channel, and therefore that it increases in rapidity during its course. ; Veins admit of a threefold division, into superficial, deep, and sinuses. The Superficial veins return the blood from the integument and su- perficial structures, and take their course between the layers of the superficial fascia ; they then pierce the deep fascia in the most con- venient and protected situations, and terminate in the deep veins. They are unaccompanied by arteries, and are’the vessels usually se- lected for venesection. ° The Deep veins are situated among the deeper structures of the body and generally in relation with the arteries ; in the limbs they are en- closed in the same sheath with those vessels, and they return the venous blood from the capillaries of the deep tissues. In company -with all the smaller, and also with the secondary arteries, as the brachial, radial, and ulnar in the upper, and the tibial and peroneal in the lower extremity, there are two veins, placed one on each side of F oy STRUCTURE OF VEINS. 367 the artery, and named vene comites. The larger arteries, as the axillary, subclavian, carotid, popliteal, femoral, &c., are accompanied by a single venous trunk. Sénuses differ from veins in their structure ; and also in their mode of distribution, being confined to especial organs and situated within their substance. The principal venous sinuses ‘are those of the dura mater, the diploé, the cancellous structure of bones, and the uterus. The communications between veins are even more frequent than those of arteries, and they take place between the larger as well as among the smaller vessels ; the vene comites communicate with each other very frequently in their course, by means of short transverse branches which pass across from one to the other. These communica- tions are strikingly exhibited in the frequent inosculations of the spinal veins, and in the various venous plexuses, as the spermatic plexus, vesical plexus, &c. The office of these inosculations is very apparent, as tending to obviate the obstructions to which the yeins are particularly liable from the thinness of their coats, and from their inability to overcome much impediment by the force of their current. Veins, like arteries, are composed of three coats, external or cellulo- fibrous, middle or fibrous, and internal or serous. The erternal coat is firm and strong, and resembles that of arteries. The middle coat consists of two layers, an outer layer of contractile fibrous tissue dis- posed in a circular direction around the vessel, and an inner layer of organic muscular fibres arranged longitudinally. This latter resem- bles the inner layer of the middle coat of arteries, but is somewhat thicker, and is not unfrequently hypertrophied. The internal coat, as in arteries, consists of a striated or fenestrated layer, and a layer of epithelium ; it is continuous with the internal coat of arteries through the medium of the lining membrane of the heart on the one hand, and through the capillary vessels on the other. The differences in structure, therefore, between arteries and veins relate to the differ- ence of thickness of their component layers, and to the absence of the elastic coat in the latter. Moreover, another difference occurs in the presence of valves. The valves of veins are composed of a thin layer of fibrous membrane, lined upon its two surfaces by epithelium. The segments or flaps of the valves of veins are semilunar in form and arranged in pairs, one upon either side of the vessel ; in some in- stances there is but a single flap, which has a spiral direction, and occasionally there are three. The free border of the valvular flaps is concave, and directed forwards, so that while the current of blood is permitted to flow freely towards the heart, the valves are distended and the current intercepted if the stream becomes retrograde in its course. Upon the cardiac side of each valve the vein is expanded into two pouches (sinuses), corresponding with the flaps of the valves, which give to the distended or injected vein a knotted appearance. The valves are most numerous in the veins of the extremities, particu- larly in the deeper veins, and they are generally absent in the very small yeins, and in the veins of the viscera, as in the portal and cere- 368 VEINS. OF THE HEAD AND NECK. bral veins: they are also absent in the large trunks, as in the ven cave, vene azygos, innominate, and iliac veins. Sinuses are venous channels, excavated in the structure of an organ, and lined by the internal coat of the veins ; of this structure are the sinuses of the dura mater, whose external covering is the fibrous tissue of the membrane, and the internal, the serous layer of the veins. The external investment of the sinuses of the uterus is the tissue of that organ; and that of the bones, the lining membrane of the cells and canals. Veins, like arteries, are supplied with nutritious vessels, the vasa vasorum ; and it is to be presumed that nervous filaments are distri- buted in their coats. I shall describe the veins according to the primary division of the body ; taking first, those of the head and neck; next, those of the upper extremity ; then, those of the lower extremity ; and lastly, th veins of the trunk. VEINS OF THE HEAD AND NECK. The veins of the head and neck may be arranged into three groups, viz. 1. Veins of the exterior of the head. 2. Veins of the diploé and interior of the cranium. 3. Veins of the neck. The veins of the exterior of the head are the— Facial, Internal maxillary, Temporal, Temporo-maxillary, Posterior auricular, Occipital. The Facial vein commences upon the anterior part of the skull in a venous plexus, formed by the communications of the branches of the temporal, and descends along the middle line of the forehead, under the name of frontal vein, to the root of the nose, where it is connected with its fellow of the opposite side by a communicating trunk which constitutes the nasal arch. There are usually two frontal veins which communicate by a transverse inosculation ; but sometimes the vein is single and bifurcates at the root of the nose, into the two an- gular veins. From the nasal arch, the frontal is continued downwards by the side of the root of the nose, under the name of the angular vein ; it then passes beneath the zygomatic muscles and becomes the facial vein, and descends along the anterior border of the masseter muscle, crossing the body of the lower jaw, by the side of the facial artery, to the submaxillary gland, and from thence to the internal jugular vein in which it terminates. The branches which the facial vein receives in its course are, the a ne See eee i a a ale ee a i Cir) Fo a yy ee ee a. a ee se VEINS OF THE DIPLOE. 369 supra-orbital, which joins the frontal vein; the dorsal veins of the nose which terminate in the nasal arch ; the ophthalmic, which communi- cates with the angular vein; the palpebral and nasal, which open into the angular vein; a considerable trunk, the alveolar, which returns the blood from the spheno-maxillary fossa, from the infra-orbital, palatine, vidian, and spheno-palatine veins, and joins the facial be- neath the zygomatic process of the superior maxillary bone, and the veins corresponding with the branches of the facial artery. The Internal maxillary vein receives the branches from the zygo- matic and pterygoid fosse ; these are so numerous and communicate so freely as to constitute a pterygoid plexus. Passing backwards behind the neck of the lower jaw, the internal maxillary joins with the temporal vein, and the common trunk resulting from this union consti- tutes the temporo-mazillary vein. The Temporal vein commences on the vertex of the head by a plexi- form network which is continuous with the frontal, the temporal, auricular and occipital veins. The ramifications of this plexus form an anterior and a posterior branch which unite immediately above the zygoma; the trunk is here joined by another large vein, the middle temporal, which collects the blood from the temporal muscle, and around the outer segment of the orbit, and pierces the temporal fascia near the root of the zygoma. The temporal vein then descends between the meatus auditorius externus and the condyle of the lower jaw, and unites with the internal maxillary vein, to form the temporo-maxillary. The Temporo-mazillary vein formed by the union of the temporal and internal maxillary, passes downwards in the substance of the parotid gland to its lower border, where it becomes the external jugular vein. Jt receives in its course the anterior auricular, masse- teric, transverse facial, and parotid veins, and near its termination is joined by the posterior auricular vein. The Posterior auricular vein communicates with the plexus upon the vertex of the head, and descends behind the ear to the temporo- maxillary vein, immediately before that vessel merges in the external jugular. It receives in its course the veins from the external ear and the stylo-mastoid vein. The Occipital vein commencing posteriorly in the plexus of the vertex of the head, follows the direction of the occipital artery, and passing deeply beneath the muscles of the back part of the neck, terminates in the internal jugular vein. This vein communicates with the lateral sinus by means of a large branch which passes through the mastoid foramen, the mastoid vein. : VEINS OF THE DIPLOE, The diploé of the bones of the head is furnished in the adult with irregular sinuses, which are formed by a continuation of the internal coat of the veins into the osseous canals in which they are lodged. At 2B 370 SINUSES OF THE DURA MATER. the middle period of life these sinuses are confined to the particular bones; but in old age, after the ossification of the sutures, they may be ‘traced from one bone to the next. They receive their blood from the ~ capillaries supplying the cellular structure of the diploé, and terminate externally in the veins of the pericranium, and internally in the veins and sinuses of the dura mater. These veins are separated from the bony walls of the canals by a thin layer of medulla. » CEREBRAL AND CEREBELLAR VEINS. The cerebral veins are remarkable for the absence of valves, and for the extreme tenuity of their coats. They may be arranged into the superficial, and deep or ventricular veins. ; The Superficial cerebral veins are situated upon the surface of the hemispheres, lying in the grooves formed by the convexities of the convolutions. They are named from the position which they may chance to occupy upon the surface of this organ, either superior or in- ferior, internal or external, anterior or posterior. The Superior cerebral veins, seven or eight in number on each side, pass obliquely forwards, and terminate in the superior longitudinal sinus, in the opposite direction to the course of the stream of blood in the sinus. The Deep or Ventricular veins commence within the lateral ventricles by the veins of the corpora striata and those of the choroid plexus, which unite to form the two vene Galeni. The Vene Galeni pass backwards in the structure of the velum in- terpositum ; and escaping through the fissure of Bichat, terminate in the straight sinus. The Cerebellar veins are disposed, like those of the cerebrum, on the surface of the lobes of the cerebellum ; they are situated some upon the superior, and some upon the inferior surface, while others occupy the borders of the organ. They terminate in the lateral and petrosal sinuses. SINUSES OF THE DURA MATER, The sinuses of the dura mater are irregular channels, formed by the splitting of the layers of that membrane, and lined upon their inner surface by a continuation of the internal coat of the veins. They may be divided into two groups:—1l. 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 sinus, Inferior longitudinal sinus, Straight sinus, Occipital sinuses, Lateral sinuses. SUPERIOR LONGITUDINAL SINUS. 371 The Superior longitudinal sinus is situated in the attached margin of the falx cerebri, and extends along the middle line of the arch of the skull, from the foramen caecum in the frontal, to the inner tuberosity of the occipital bone, where it divides into the two lateral sinuses. It is triangular in form, is small in front, and increases gradually in size as it passes backwards; it receives the superior cerebral veins which open into it obliquely, numerous small veins from the diploé, and near the posterior extremity of the sagittal suture the parietal veins, from the pericranium and scalp. Examined in its interior, it presents numerous transverse fibrous bands (trabeculz) the chord Willisii, which are stretched across its inferior angle; and some small white granular masses, the glandule Pacchioni; the oblique openings of the cerebral veins, with their valve-like margin, are also seen upon the walls of the sinus. The termination of the superior longitudinal sinus in the two lateral Fig. 132.* sinuses forms a considerable dilatation, into which the straight sinus opens from the front, and the occipital sinuses from below. This dila- * The sinuses of the upper and back part of the skull. 1. The superior lon- gitudinal sinus. 2, 2. The cerebral veins opening into the sinus from behind forwards. 3. The falx cerebri. 4. The inferior longitudinal sinus. 5. The straight or fourth sinus. 6. The venze Galeni. 7. The torcular Herophili. 8, The two lateral sinuses, with the occipital sinuses between them. 9. The ter- mination of the inferior petrosal sinus of one side. 10. The dilatations cor- responding with the jugular fossze. 11. The internal jugular veins, 372 LATERAL SINUSES. tation is named the torcular Herophili,* and is the point of communica- tion of six sinuses, the superior longitudinal, two lateral, two occipital ‘and the straight. The Inferior longitudinal sinus is situated in the free margin of the falx cerebri; it is cylindrical in form, and extends from near the erista galli to the anterior border of the tentorium, where it terminates in the straight sinus. It receives in its course several veins from the The Straight or fourth sinus is the sinus of the tentorium; it is situated at the line of union of the falx with the tentorium; is prismoid in form, and extends across the tentorium, from the termination of the inferior longitudinal sinus to the torcular Herophili. It receives the ven Galeni, the cerebral veins from the inferior part of the pos- terior lobes, and the superior cerebellar veins. The Occipital sinuses are two canals of small size, situated in the attached border of the falx cerebelli; they commence by several small veins around the foramen magnum, and terminate by separate openings in the toreular Herophili. ‘They not unfrequently communi- cate with the termination of the lateral sinuses. The Lateral sinuses, commencing at the torcular Herophili, pass horizontally outwards, in the attached margin of the tentorium, and then curve downwards and inwards along the base of the petrous portion of the temporal bone, at each side, to the foramina lacera posteriora, where they terminate in the internal jugular veins. Each sinus rests in its course upon the transverse groove of the occipital bone, posterior inferior angle of the parietal, mastoid portion of the temporal, and again on the occipital bone. They receive the cerebral veins from the inferior surface of the posterior lobes, the inferior cerebellar veins, the superior petrosal sinuses, the mastoid, and posterior condyloid veins, and at their termination, the inferior petrosal sinuses. sey sinuses are often unequal in size, the right being larger than the eit. The sinuses of the base of the skull are the— Cavernous, Inferior petrosal, Circular, Superior petrosal, Transverse. The Cavernous sinuses are named from presenting a structure similar to that of the corpus cavernosum penis. They are situated on each side of the sella turcica, receiving, anteriorly, the ophthalmic veins through the sphenoidal fissures, and terminating posteriorly in the in- ferior petrosal sinuses. In the internal wall of each cavernous sinus is * Torcular (a press), from a supposition entertained by the older anatomists pri the ba of blood, coming in different directions, compressed each other at this point. INFERIOR PETROSAL SINUSES. 373 the internal carotid artery, accompanied by several filaments of the carotid plexus, and crossed by the sixth nerve; and, in its external wall, the third, fourth, and ophthalmic nerves. These structures are separated from the blood flowing through the sinus, by the tubular lining membrane. The cerebral veins from the under surface of the anterior lobes, open into the cavernous sinuses. They communicate by means of the ophthalmic with the facial veins, by the circular sinus with each other, and by the superior petrosal with the lateral sinuses. The Inferior petrosal sinuses are the continuations of the cavernous sinuses backwards along the lower border of the petrous portion of the Fig. 133.* temporal bone at each side of the base of the skull, to the foramina lacera posteriora, where they terminate with the lateral sinuses in the commencement of the internal jugular veins. * The sinuses of the base of the skull. 1. The ophthalmic veins. 2. The cavernous sinus of one side. 3. The circular sinus; the figure occupies the position of the pituitary gland in the sella turcica. 4. The inferior petrosal sinus. 5. The transverse or anterior occipital sinus. 6. The superior petrosal sinus. 7 The internal jugular vein. 8. The foramen magnum. 9. The occipital sinuses. 10. The torcular Herophili. 11, 11. The lateral sinuses. 374 . ‘ VEINS OF THE NECK. The Circular sinus (sinus of Ridley) is situated in the sella turcica, surrounding the pituitary giand, and communicating on each side ' with the cavernous sinus. The posterior segment is larger than the anterior. The Superior petrosal sinuses pass obliquely backwards along the attached border of the tentorium, on the upper margin of the petrous portion of the temporal bone, and establish a communication between the cavernous and lateral sinus at each side. They receive one or two cerebral veins from the inferior part of the middle lobes, and a cerebellar vein from the anterior border of the cerebellum. Near the extremity of the petrous bone these sinuses cross the oval aperture which trans- mits the fifth nerve. The Transverse sinus (basilar, anterior occipital) passes transversely across the basilar process of the occipital bone, forming a communica- tion between the two inferior petrosal sinuses. Sometimes there are two sinuses in this situation. VEINS OF THE NECK. The veins of the neck which return the blood from the head are the— External jugular, Anterior jugular, Internal jugular, Vertebral. The External jugular vein is formed by the union of the pos- terior auricular vein with the temporo-maxillary, and commences at the lower border of the parotid gland, in front of the sterno-mastoid muscle. It descends the neck in the direction of a line drawn from the angle of the lower jaw to the middle of the clavicle, crosses the sterno- mastoid, and terminates near the posterior and inferior attachment of that muscle in the subclavian vein. In its course downwards it lies upon the anterior lamella of the deep cervical fascia, which separates it from the sterno-mastoid muscle, and is covered in by the platysma myoides and superficial fascia. At the root of the neck it pierces the deep cervical fascia; it is accompanied, for the upper half of its course, by the auricularis magnus nerve. The branches which it re- ceives are the occipital cutaneous and posterior cervical cutaneous, and, near its termination, the supra and posterior scapular. The external jugular vein is very variable in size, and is occasionally replaced by two veins. In the parotid gland it receives a large com- municating branch from the internal jugular vein. The Anterior jugular vein is a trunk of variable size, which col- lects the blood from the integument and superficial structures on the fore part of the neck. It passes downwards along the anterior border of the sterno-mastoid muscle, and opens into the subclavian vein, near the termination of the external jugular. The two veins communicate SU ac ee ee ee eee ree a a oe ee ee a ee a we Te a eS ee Ce, VEINS OF THE UPPER EXTREMITY. 375 with each other, with the external, and with the internal jugular. vein. The Internal jugular vein, formed by the convergence of the lateral and inferior petrosal sinus, commences at the foramen lacerum poste- rius on each side of the base of the skull, and descends the side of the neck, lying, in the first instance, to the outer side of the internal carotid, and then upon the outer side of the common carotid artery to the root of the neck, where it unites with the subclavian, and consti- tutes the vena innominata. At its commencement, the internal jugu- lar vein is posterior and external to the internal carotid artery, and the eighth and ninth pairs of nerves; lower down, the vein and artery are on the same plane, the glosso-pharyngeal and hypoglossal nerves passing forwards between them, the pneumogastric being between and behind in the same sheath, and the nervus accessorius crossing ob- liquely behind the vein. The Branches which the internal jugular receives in its course are, the facial, the lingual, the inferior pharyngeal, the occipital, and the superior and inferior thyroid veins. The Vertebral vein descends by the side of the vertebral artery in the canal formed by the foramina in the transverse processes of the cervical vertebrae, and terminates at the root of the neck in the com- mencement of the vena innominata. In the lower part of the vertebral canal it frequently divides into two branches, one of which advances forwards, while the other passes through the foramen in the transverse process of the seventh cervical vertebra, before opening into the vena innominata. The Branches which it receives in its course are the posterior condy- loid vein, muscular branches, the cervical meningo-rachidian veins, and, near its termination, the superficial and deep cervical veins. The Inferior thyroid veins, two, and frequently more in number, are situated one on each side of the trachea, and receive the venous blood from the thyroid gland. They communicate with each other and with the superior thyroid veins, and form a plexus upon the front of the trachea, The right vein terminates in the right vena innominata, just at its union with the superior cava, and the left in the left vena innominata. VEINS OF THE UPPER EXTREMITY. The veins of the upper extremity are the deep and superficial. The deep veins accompany the branches and trunks of the arteries, and constitute their vene comites. The venz comites of the radial and ulnar arteries are enclosed in the same sheath with those vessels, and terminate at the bend of the elbow in the brachial veins. The brachial venze comites are situated one on each side of the artery, and open into the axillary vein; the axillary becomes the subclavian, and the subclavian unites with the internal jugular to form the vena inno- minata. 376 CEPHALIC VEIN. The Superficial veins of the fore-arm are the— Anterior ulnar vein, Posterior ulnar vein, Basilic vein, Radial vein, Cephalic vein, Median vein, Median basilic, Median cephalic. The Anterior ulnar vein collects the venous blood from the inner border of the hand, and from the vein of the little-finger, vena salva- tella, and ascends the inner side of the fore-arm to the bend of the elbow, where it becomes the basilic vein. The Posterior ulnar vein, irregu- lar in size, and frequently absent, ‘commences upon the inner border and posterior aspect of the hand, and ascending the fore-arm termi- nates in front of the inner condyle, in the anterior ulnar vein. The Basilic vein (Baciasxos, royal, or principal) ascends from the com- mon ulnar vein formed by the two preceding, along the inner side of i the upper arm, and near its middle pierces the fascia; it then passes upwards to the axilla, and becomes the axillary vein. The Radial vein commences in the large vein of the thumb, on the outer and posterior aspect of the hand, and ascends along the outer border of the fore-arm to the bend of the elbow, where it becomes the cephalic vein. . The Cephalic vein (xe@arn the head) ascends along the outer side Fig. 134,* * The veins of the fore-arm and bend of the elbow. 1. The radial vein. 2. The cephalic vein. 3. The anterior ulnar vein. 4. The posterior ulnar vein. 5. The trunk formed by their union. 6. The basilic vein, piercing the deep fascia at7. 9. A communicating branch between the deep veins of the fore-arm and the upper part of the median vein. 10. The median cephalic vein. 11. The median basilic. 12. A slight convexity of the deep fascia, formed by the brachial artery. 13. The process of fascia, derived from the tendon of the biceps, and separating the median basilic vein from the brachial artery. 14. The exter- nal cutaneous nerve, piercing the deep fascia, and dividing into two branches, which pass behind the median cephalic vein. 15. The internal cutaneous nerve, dividing into branches, which pass in front of the median basilic vein. 16. The intercosto-humeral cutaneous nerve. 17. The spiral cutaneous nerve, a branch of the musculo-spiral. ; AXILLARY VEIN, 377 of the arm to its upper third; it then enters the groove between the pectoralis major and deltoid muscles, where it is in relation with the descending branch of the thoracico-acromialis artery, and terminates beneath the clavicle in the subclavian vein. A large communicating branch sometimes crosses the clavicle between the external jugular and this vein, which gives it the appearance of being derived directly from the head—hence its appellation. The Median vein is intermediate between the anterior ulnar and - radial vein ; it collects the blood from the anterior aspect of the fore- arm, communicating with the two preceding. At the bend of the elbow it receives a branch from the deep veins, and divides into two branches, the median cephalic and median basilic. The Median cephalic vein, generally the smaller of the two, passes obliquely ‘outwards, in the groove between the biceps and supinator longus, to join the cephalic vein. The branches of the external cuta- neous nerve pass behind it. The Median basilie vein passes obliquely inwards, in the groove between the biceps and pronator radii teres, and terminates in the basilic vein. This vein is crossed by one or two filaments of the in- ternal cutaneous nerve, and is separated from the brachial artery by the aponeurotic slip given off by the tendon of the biceps. AXILLARY VEIN. The axillary vein is formed by the union of the venz comites of the brachial artery with the basilic vein. It lies in front of the artery, and receives numerous branches from the collateral veins of the. branches of the axillary artery; and, at the lower border of the first rib, becomes the subclavian vein. SUBCLAVIAN VEIN. The subclavian vein crosses over the first rib and beneath the clavicle, and unites with the internal jugular vein to form the vena innominata, It lies at first in front of the subclavian artery, and then in front of the scalenus anticus, which separates it from that vessel. The phrenic and pneumogastric nerves pass between the artery and vein. The veins opening into the subclavian are the cephalic below the clavicle, and the external and anterior jugulars above ; occasionally some small veins from the neighbouring parts also terminate in it. VEINS OF THE LOWER EXTREMITY. The veins of the lower extremity are the deep and superficial. The deep veins accompany the branches of the arteries in pairs, and form the venz comites of the anterior and posterior tibial and peroneal arteries. These veins unite in the popliteal region to form a single vein of large size, the popliteal, which successively becomes in its course the femoral and the external iliac vein. 378 POPLITEAL VEIN. The popliteal vein ascends through the popliteal region, lying, in the first instance, directly upon the artery, and then getting somewhat to its outer side. It receives several muscular and articular branches, and the external saphenous vein. The valves in this vein are four or five in number. FEMORAL VEIN. The femoral vein, passing through the opening in the adductor magnus muscle, ascends the thigh in the sheath of the femoral artery, and entering the pelvis beneath Poupart’s ligament, becomes the ex- ternal iliac vein. In the lower part of its course it is situated upon the outer side of the artery; it then becomes placed behind that vessel, and, at Poupart’s ligament, lies to its inner side. It receives the muscular veins, and the profunda, and, through the saphenous open- ing, the internal saphenous vein. The valves in this vein are four or five in number. The Profunda vein is formed by the convergence of the numerous small veins which accompany the branches of the artery; it is a vein of large size, lying in front of the profunda artery, and terminates in the femoral at about an inch and a half below Poupart’s ligament. The Superficial veins are the external or short, and the internal or long saphenous. The External saphenous vein collects the blood from the outer side of the foot and leg. It passes behind the outer ankle, ascends along the posterior aspect of the leg, lying in the groove between the two bellies of the gastrocnemius muscle, and pierces the deep fascia in the popliteal region to join the popliteal vein. It receives several cuta- neous branches in the popliteal region before passing through the deep fascia, and is accompanied in its course eh the external saphenous nerve. The Internal saphenous vein commences upon the dorsum and inner side of the foot. It ascends in front of the inner ankle, and along the inner side of the leg; it then passes behind the inner condyle of the femur and along the inner side of the thigh to the saphenous open- ing, where it pierces the sheath of the femoral vessels, and terminates in the femoral vein, at about one inch and a half below Poupart’s ligament. It receives in its course the cutaneous veins of the leg and thigh, and communicates freely with the deep veins. At the saphenous opening it is joined by the superficial epigastric und circumflexa ilii veins, and by the external pudic. The situation of this vein in the thigh is not unfrequently occupied by two or even three trunks of nearly equal size. 379 VEINS OF THE TRUNK. The veins of the trunk may be divided into 1. The superior vena cava, with its formative branches. 2. The inferior vena cava, with its formative branches. 3 The azygos veins. 4. The vertebral and spinal veins. 5. The cardiac veins. 6. The portal vein. 7. The pulmonary veins. SUPERIOR VENA CAVA, WITH ITS FORMATIVE BRANCHES. Vene Innominate. The Vene innominate are two large trunks, formed by the union of the internal jugular and subclavian vein, at each side of the root of the neck. The Right vena innominata, about an inch and a quarter in length, lies superficially and externally to the arteria innominata, and descends almost vertically to unite with its fellow of the opposite side in the formation of the superior cava. At the junction of the jugular and subclavian veins it receives from behind the ductus lymphaticus dexter, and lower down it has opening into it the right vertebral, right internal mammary and right inferior thyroid vein. The Left vena innominata, considerably longer than the right, ex- tends almost horizontally across the roots of the three arteries arising from the arch of the aorta, to the right side of the mediastinum, where it unites with the right vena innominata, to constitute the supe- rior cava, It is in relation in front with the left sterno-clavicular articulation and the first piece of the sternum. At its commencement it receives the thoracic duct which opens into it from behind, and in its course is joined by the left vertebral, left inferior thyroid, left mammary, and by the superior intercostal vein. It also receives some small veins from the mediastinum and thymus gland. There are no valves in the venz innominate. SUPERIOR VENA CAVA. The superior cava is a short trunk about three inches in length, formed by the junction of the two venz innominate. It descends perpendicularly on the right side of the mediastinum, and entering the pericardium terminates in the upper part of the right auricle. It is in relation 7x front with the thoracic fascia, which separates it from the thymus gland, and with the pericardium; behind with the right pulmonary artery, and right superior pulmonary vein ; internally with the ascending aorta; externally with the right phrenic nerve, and right lung. Immediately before entering the pericardium it receives the vena azygos major. "4 380 INFERIOR VENA CAVA, WITH ITS FORMATIVE BRANCHES. Iliac Veins. Fig. 135.* The Eaternal iliac vein lies to the inner side of the correspond- ing artery at the os pubis; but gradually gets behind it as it passes upwards along the brim of the pelvis, and terminates opposite the sacro-iliac sym- - physis by uniting with the in- ternal iliac, to form the common iliac vein. Immediately above Poupart’s ligament it receives the epigastric and circumflexa ilii veins; it has no valves. The Internal iliac vein is formed by vessels which cor- respond with the branches of the internal iliac artery ; it re- ceives the returning blood from the gluteal, ischiatic, internal pudic, and obturator veins, ex- ternally to the pelvis ; and from the vesical and uterine plexuses within the pelvis. The vein lies to the inner side of the in- ternal iliac artery, and termi- nates by uniting with the ex- ternal iliac vein, to form the common iliac. The Vesical and prostatic pleaus is an important plexus of veins which surrounds the neck and base of the bladder and prostate gland, and receives its blood from the great dorsal vein of the penis, and from the veins of the external organs of generation. It is retained in connection with the sides of the bladder by a reflexion of the pelvic fascia. * ‘The veins of the trunk and neck. 1. The superior vena cava. 2. The left vena innominata. 3. The right vena innominata. 4. The right subclavian vein. 5. The internal jugular vein. 6. The external jugular. 7, The anterior jugular. 8, The inferior vena cava. 9. The external iliac vein, 10. The in- INFERIOR VENA CAVA. 381 The Uterine plexus is situated around the vagina, and upon the sides of the uterus, between the two layers of the broad ligaments. The veins forming the vesical and uterine plexus are very subject to the production of phlebolites. The Common iliac veins are formed by the union of the external and internal iliac vein on each side of the pelvis. The right common iliac, shorter than the left, ascends obliquely behind the correspond- ing artery ; and upon the intervertebral substance between the fourth and fifth lumbar vertebra, unites with the vein of the opposite side, to-form the inferior cava. The left common iliac, longer and more oblique than the right, ascends behind, and. a little internally to the corresponding artery, and passes beneath the right common iliac artery, near its origin, to unite with the right vein in the formation of the inferior vena cava. The right common iliac vein has no branch open- ing into it; the left receives the vena sacra media. These veins have no valves. INFERIOR VENA CAVA. The inferior vena cava is formed by the union of the two common iliac veins, upon the intervertebral substance between the fourth and fifth lumbar vertebra. It ascends along the front of the vertebral column, on the right side of the abdominal aorta, and passing through the fissure in the posterior border of the liver and the quadrilateral opening in the tendinous centre of the diaphragm, terminates in the inferior and posterior part of the right auricle. There are no valves in this vein. It is in relation from below upwards, iz front with the mesentery transverse duodenum, portal vein, pancreas, and liver, which latter nearly and sometimes completely surrounds it ; behind it rests upon the vertebral column and right crus of the diaphragm, from which it is se- parated-by the right renal and lumbar arteries; to the right it has the peritoneum and sympathetic nerve; and to the left the aorta. The Branches which the inferior cava receives in its course, are the— Lumbar, Right spermatic, Renal, Supra-renal, Phrenic, Hepatic. ternal iliac vein. 11. The common iliac veins; the small vein between these is the vena sacra media. 12, 12. Lumbar veins. 13. The right spermatic vein. 14. The left spermatic, opening into the left renal vein. 15. The right renal vein. 16, The trunk of the hepatic veins. 17. The greater vena azygos, com- mencing inferiorly in the lumbar veins. 18. The lesser vena azygos, also com- mencing in the lumbar veins. 19. A branch of communication with the left renal vein. 20, The termination of the lesser in the greater vena azygos. 21. The superior intercostal vein; communicating inferiorly with the lesser vena azygos, and terminating superiorly in the left vena innominata. “N 382 AZYGOS VEINS, The Lumbar veins, three or four in number on each side, collect the venous blood from the muscles and integument of the loins, and from the spinal veins: the left are longer than the right from the position of the vena cava. The Right spermatic vein is formed by the two veins which return the blood from the venous plexus, situated in the spermatic cord. These veins follow the course of the spermatic artery, and unite to form the single trunk which opens into the inferior vena cava. The left spermatic vein terminates in the left renal vein. The Ovarian veins represent the spermatic veins of the male, and collect the venous blood from the ovaries, round ligaments, and Fallo- pian tubes, and communicate with the uterine sinuses. They terminate as in the male. The Renal or emulgent veins return the blood from the kidneys ; their branches are situated in front of the divisions of the renal arteries, and the left opens into the vena cava somewhat higher than the right. The deft is longer than the right in consequence of the position of the vena cava, and crosses the aorta immediately below the origin of the superior mesenteric artery. It receives the left spermatic vein, which terminates in it at right angles: hence the more frequent occurrence of varicocele on the left than on the right side. The Supra-renal veins terminate partly in the renal veins, and partly in the inferior vena cava. The Phrenic veins return the blood from the ramifications of the phrenic arteries; they open into the inferior cava. The Hepatic veins form two principal trunks and numerous smaller veins which open into the inferior cava, while that vessel is situated in the posterior border of the liver. The hepatic veins commence in the liver by minute venules, the intralobular veins, in the centre of each lobule; these pour their blood into larger vessels, the suwblobular veins; and the sublobular veins constitute by their convergence and union, the hepatic trunks, which terminate in the inferior vena cava. AZYGOS VEINS. The azygos veins form a system of communication between the su- perior and inferior vena cava, and serve to return the blood from that part of the trunk of the body in which those vessels are deficient, on account of their connection with the heart. This system consists of three vessels, the Vena azygos major, Vena azygos minor, Superior intercostal vein. The Vena azygos major commences in the lumbar region by a com- munication with the lumbar veins; sometimes it is joined by a branch directly from the inferior vena cava, or by one from the renal vein. on welincalinh goa Si ribe Reins VERTEBRAL AND SPINAL VEINS. 383 It passes through the aortic opening in the diaphragm, and ascends upon the right side of the vertebral column to the third dorsal verte- bra, where it arches forwards over the right bronchus, and terminates in the superior cava. It receives all the intercostal veins of the right side, the vena azygos minor, and the bronchial veins. The Vena azygos minor commences in the lumbar region, on ‘the left side, by a communication with the lumbar or renal veins. It passes beneath the border of the diaphragm, and ascending upon the left side of the vertebral column crosses the fifth or sixth dorsal ver- tebra to open into the vena azygos major. It receives the six or seven lower intercostal veins of the left side. The azygos veins have no valves. The Superior intercostal vein is the trunk formed by the union of the five or six upper intercostal veins of the left side. It communicates below with the vena azygos minor, and ascends to terminate in the left vena innominata. VERTEBRAL AND SPINAL VEINS. The numerous venous plexuses of the vertebral column and spinal cord may be arranged into three groups:— Dorsi-spinal, Meningo-rachidian, Medulli-spinal. The Dorsi-spinal veins form a plexus around the spinous, transverse and articular processes, and arches of the vertebre. They receive the returning blood from the dorsal muscles and surrounding structures, and transmit it, in part to the meningo-rachidian, and in part to the vertebral, intercostal, lumbar, and sacral veins. The Meni hidian veins are situated between the theca verte- bralis and the vertebra. They communicate freely with each other by means of a complicated plexus. In front they form two longitudi- nal trunks, (longitudinal spinal sinuses,) which extend the whole length of the column on each side of the posterior common ligament, and are joined on the body of each vertebra by transverse trunks, which pass beneath the ligament, and receive the large basi-vertebral veins from the interior of each vertebra. The meningo-rachidian veins com- municate superiorly through the anterior condyloid foramina with the internal jugulars; in the neck they pour their blood into the vertebral veins ; in the thorax, into the intercostals; and in the loins and pelvis into the lumbar and sacral veins, the communications being established through the intervertebral foramina. The Medulli-spinal veins are situated between the pia mater and arachnoid ; they communicate freely with each other to form plexuses, and send branches through the intervertebral foramina with each of the spinal nerves, to join the veins of the trunk. 384 CARDIAC VEINS. CARDIAC VEINS. The veins returning the blood from the substance of the heart, are the— Great cardiac vein, Posterior cardiac veins, Anterior cardiac veins, Venz Thebesii. The Great cardiac vein (coronary ) commences at the apex of the heart, and ascends along the anterior ventricular groove to the base of the ventricles ; it then curves around the left auriculo-ventricular groove to the posterior part of the heart, where it terminates in the right auricle. It receives in its course the left cardiac veins from the left auricle and ventricle, and the posterior cardiac veins from the pos- terior ventricular groove. The Posterior cardiac vein, frequently two in number, commences also at the apex of the heart, and ascends along the posterior ventri- cular groove, to terminate in the great cardiac vein. It receives the veins from the posterior aspect of the two ventricles. The Anterior cardiac veins collect the blood from the anterior sur- face of the right ventricle; one larger than the rest runs along the right border of the heart and joins. the trunk formed by these veins, which curves around the right auriculo-ventricular groove, to terminate in the great cardiac vein near its entrance into the right auricle. The Vene Thebesii are numerous minute venules which convey the venous blood directly from the substance of the heart into its four cavities. Their existence is denied by some anatomists. PORTAL SYSTEM. The portal system is composed of four large veins which return the blood from the chylopoietic viscera; they are the— Inferior mesenteric vein, Superior mesenteric vein, Splenic vein, Gastric veins. The Inferior mesenteric vein receives its blood from the rectum by means of the hemorrhoidal veins, and from the sigmoid flexure and descending colon, and ascends behind the transverse duodenum and pancreas, to terminate in the splenic vein. Its hemorrhoidal branches inosculate with the branches of the internal iliac vein, and thus establish a communication between the portal and general venous system, The Superior mesenteric vein is formed by branches which collect ae ae eee Pe et et SPLENIC VEIN. 385 the venous blood from the capillaries of the superior mesenteric artery; they constitute by their junction a large trunk, which ascends by the side of the corresponding artery, crosses the transverse duodenum, and unites behind the pancreas with the splenic in the formation of the portal vein. The Splenic vein commences in the structure of the spleen, and quits ' Fig. 136.* : Bt rg ‘ ‘ic * The portal vein. 1. The inferior mesenteric vein ; it is traced by means of dotted lines behind the pancreas (2) to terminate in the splenic vein (3). 4, The spleen. 5. Gastric veins, opening into the splenic vein. 6. The superior mesenteric vein. 7. The descending portion of the duodenum. 8. Its trans- verse portion, which is crossed by the superior mesenteric vein and by a part of the trunk of the superior mesenteric artery. 9. The portal vein. 10. The hepatic artery. 11 The ductus communis choledochus. 12. The division of the duct and vessels at the transverse fissure of the liver. 13. The cystic duct lead- ing to the gall bladder. 2c 386 PULMONARY ‘VEINS. that organ by several large veins ; it is larger than the splenic artery, and perfectly straight in its course. It passes horizontally inwards ‘behind the pancreas, and terminates near its greater end by uniting with the superior mesenteric and forming the portal vein. It receives in its course the gastric and pancreatic veins, and near its termination the inferior mesenteric vein. The Gastric veins correspond with the gastric, gastro-epiploic, and vasa brevia arteries, and terminate in the splenic vein. The VENA porTs&, formed by the union of the splenic and superior mesenteric vein behind the pancreas, ascends through the right border of the lesser omentum to the transverse fissure of the liver, where it divides into two branches, one for each lateral lobe. In the right border of the lesser omentum it is situated behind and between the hepatic artery and ductus communis choledochus, and is surrounded by the hepatic plexus of nerves and lymphatics. At the transverse fissure each primary branch divides into numerous secondary branches which ramify through the portal canals, and give off vaginal and inter- lobular veins, and the latter terminate in the lobular venous plexus of the lobules of the liver. The portal vein within the liver receives the venous blood from the capillaries of the hepatic artery. PULMONARY VEINS. The pulmonary veins, four in number, return the arterial blood from the lungs to the left auricle of the heart; they differ from the veins in general, in the area of their cylinders being very little larger than the corresponding arteries, and in accompanying singly each branch of the pulmonary artery. They commence in the capillaries upon the parietes of the bronchial cells, and unite to form a single trunk for eachlobe. The vein of the middle lobe of the right lung unites with the superior vein so as to form the two trunks which open into the left auricle. Sometimes they remain separate, and then there are three pulmonary veins on the right side. The right pulmonary veins pass behind the superior vena caya to the left auricle, and the left behind the pulmonary artery ; they both pierce the pericardium. Within the lung the branches of the pulmonary veins are behind the bronchial tubes, and those of the pulmonary artery in front; but at the root of the lungs the veins are in front, next the arteries, and then the bronchi. There are no valves in the pulmonary veins. a ae eee ee 387 CHAPTER VII. ON THE LYMPHATICS. THE lymphatic vessels, or absorbents, have received their double appellation from certain phenomena which they present; the former name being derivable from the appearance of the limpid fluid (lympha, water) which they convey; and the latter, from their supposed pro- perty of absorbing foreign substances into the system. They are minute, delicate, and transparent vessels, remarkable for their gene- ral uniformity of size, for a knotted appearance which is due to the presence of numerous valves, for the frequent dichotomous divisions which occur in their course, and for their division into several branches immediately before entering a gland. Their office is to collect the products of digestion and the detrita of nutrition, and convey them into the venous circulation near to the heart. Lymphatic vessels commence in a delicate network which is distri buted upon the cutaneous surface of the body, upon the various surfaces of organs and throughout their internal structure ; and from this network the lymphatic vessels proceed, nearly in straight lines, in a direction towards the root of the neck. In their course they are in- tercepted by numerous small spheroid or oblong bodies, more or less flattened on their surface, lymphatic glands. The lymphatic vessels entering these glands are termed vasa inferentia or afferentia, and those which quit them vasa efferentia. The vasa inferentia vary in number from two to six, they divide at the distance of a few lines from the gland into several smaller vessels and enter it by one of the flattened surfaces.* The vasa efferentia escape from the gland on the opposite, but not unfrequently on the same surface ; they consist like the vasa inferentia at their junction with the gland of several small vessels which unite after a course of a few lines to form from one to three trunks, often twice as large as the vasa inferentia. Lymphatic vessels admit of a threefold division - into ‘apelin deep, and lacteals. The superficial lymphatic vessels, upon the surface of the body, follow the course of the veins, and pierce the deep fascia in convenient situations, to join the deep lymphatics. Upon the sur- face of organs they converge to the nearest lymphatic trunks. The superficial lymphatic glands are placed in the most protected situations * See Mr. Lane’s article on the ‘‘ Lymphatic System,’’ in the Cyclopzedia of Anatomy and Physiology. 388 GENERAL ANATOMY OF LYMPHATICS. of the superficial fascia, as in the hollow of the ham and groin in the lower extremity, and upon the inner side of the arm in the upper ex- tremity. The deep lymphatics, fewer in number and somewhat larger than the superficial vessels, accompany the deeper veins ; those from the lower parts of the body converging to the numerous glands seated around the iliac veins and inferior vena cava, and terminating in a large trunk situated upon the vertebral column, the thoracic duct. From the upper part of the trunk of the body. on the left side, and from the left side of the head and neck, they also proceed to the thoracic duct. Those on the right side of the head and neck, right upper extremity, and right side of the thorax, form a distinct duct which terminates at the point of junction of the subclavian with the internal jugular vein on the right side of the root of the neck. The Jacteals are the lymphatic vessels of the small intestines; they have received their distinctive appellation from conveying the milk- like product of digestion, the chyle, to the great centre of the lymphatic system, the thoracic duct. They are situated in the mesentery, and pass through the numerous mesenteric glands in their course. Lymphatic vessels are very generally distributed through the ani- mal tissues; there are, nevertheless, certain structures in which they have never been detected, for example, the brain and spinal cord, the eye, bones, cartilages, tendons, the membranes of the ovum, the um- bilical cord, and the placenta. The anastomoses between these vessels are less frequent than between arteries and veins ; they are effected by means of vessels of equal size with the vessels which they connect, and no increase of calibre results from their junction. The lymphatic vessels are smallest in the neck, larger in the upper extremities, and larger still in the lower limbs, For the purpose of effecting the movement of their fluids in a proper direction, lymphatic vessels are furnished with valves, and it is to these that the appearance of constrictions around the cylinders of the vessels at short distances is due. Like the valves of yeins, the valves of lymphatic vessels are each composed of two semilunar flaps attached by their convex border to the sides of the vessel and free by their concave border. This is the general character of the valves, but, as in veins, there are exceptions in their form and disposition ; sometimes one flap is so small as to be merely rudimentary, while the other is large in proportion; sometimes the flap runs all the way round the tube, leaving a central aperture which can only be closed by a contrac- tile power in the valve itself ; and sometimes instead of being circular the aperture is elliptical, and the arrangement of the flaps like that of the ileo-ceecal valve.* These peculiarities are most frequently met with at and near the anastomoses of the lymphatic vessels. The valves are most numerously met with near the lymphatic glands; next in frequency they are found in the neck and upper extremities where * Mr. Lane, loc. cit. LYMPHATICS OF THE HEAD AND NECK. ~ 389 the vessels are small, and least numerously in the lower limbs where the lymphatics are larger. In the thoracic duct an interspace of two or three inches frequently occurs between the valves. Connected with the presence of valves in the lymphatic vessels, are two lateral dilatations or pouches, analogous to the valvular sinuses of veins. These sinuses are situated on the cardiac side of the valves; they re- ceive the valves when the latter are thrown back by the current of the blood; and when reflux occurs, they become distended with a body of fluid which makes pressure on the flaps. These pouch-like dilatations and the constrictions corresponding with the line of attachment of the convex borders of the flaps are the cause of the knotted appearance of distended lymphatic vessels. Like arteries and veins, lymphatic vessels are composed of three coats, external,- middle and internal. The eaternal coat is cellulo- fibrous, like that of blood-vessels ; it is thin, but very strong, and serves to connect the vessel to surrounding tissues, at the same time that it forms a protective covering. The middle coat is thin and elastic, and consists of a layer of longitudinal fibres analogous to those of the innermost layer of the middle coat of arteries and veins. Some few circular fibres may be seen externally to these in the larger lym- phatic vessels. The ixternal coat is inelastic and more liable to rup- _ ture than the other coats. It is a serous layer continuous with the lining membrane of the veins, and invested by an epithelium. The valves are composed of a very thin layer of fibrous tissue coated on its two surfaces by epithelium. The lymphatic glands (conglobate, absorbent) are small oval and somewhat flattened or rounded bodies, composed of a plexus of minute lymphatic vessels, associated with a plexus of blood-vessels, and en- closed in a thin cellular capsule. When examined on the surface they are seen to have a lobulated appearance, while the face of a section is cellular from the division of the numberless convolutions which are formed by the lymphatic vessels within its substance. The colour of the glands is a pale pink, excepting those of the lungs, the bronchial glands, which in the adult are more or less mottled with black, and are sometimes filled with a black pigment. Lymphatic glands are larger in the young subject than in the adult, and are smallest in old age ; they as well as their vessels are supplied with arteries, veins and nerves, like other structures. I shall describe the lymphatic vessels and glands according to the arrangement adopted for the veins, commencing with those of the head and neck, and proceeding next to those of the upper extremity, lower extremity, and trunk. . LYMPHATICS OF THE HEAD AND NECK, The Superficial lymphatie glands of the head and face are small, few in number, and isolated; they are the occipital, which are situated 390. LYMPHATICS OF THE UPPER EXTREMITY. near the origin of the occipito-frontalis muscle ; posterior auricular, be- hind the ear ; parotid, in the parotid gland ; zygomatic, in the zygomatic fossa ; buccal, upon the buccinator muscle ; and suwbmaaillary, beneath the margin of the lower jaw. There are no deep lymphatic glands within the cranium. The Superficial cervical lymphatic glands are few in number and small ; they are situated in the course of the external jugular vein, be- tween the sterno-mastoid and trapezius muscles, at the root of the neck, and about the larynx. The Deep cervical glands (glandule concatenate) are numerous and of large size ; they are situated around the internal jugular vein and sheath of the carotid arteries, by the side of the pharynx, cesophagus, and trachea, and extend from the base of the skull to the root of the neck, where they are in communication with the lymphatic vessels and glands of the thorax. The Superficial. lymphatic vessels of the head and face are disposed in three groups ; occipital, which take the course of the occipital vein to the occipital and deep cervical glands; temporal, which follow the branches of the temporal vein to the parotid and deep cervical glands ; and facial, which accompany the facial vein to the submaxillary lym- phatic glands. The Deep lymphatic vessels of the head are the meningeal and cere- bral ; the former are situated in connection with the meningeal veins, and escape through foramina at the base of the skull, to join the deep cervical glands. The cerebral lymphatics, according to Fohmann, are situated upon the surface of the pia mater, none having yet been dis- covered in the substance of the brain. They pass most probably through the foramina at the base of the skull, to terminate in the deep cervical glands. The Deep lymphatic vessels of the face proceed from the nasal fosse, mouth, and pharynx, and terminate in the submaxillary and deep cervical glands. | The Superficial and deep cervical lymphatic vessels accompany the jugular veins, passing from gland to gland, and at the root of the neck communicate with the thoracic lymphatic vessels, and terminate, on the right side, in the ductus lymphaticus dexter, and, on the left, in the thoracic duct, near its termination. LYMPHATICS OF THE UPPER EXTREMITY. The Superficial lymphatic glands of the arm are not more than four or five in number, and of very small size. One or two are situated near the median basilic and cephalic veins, at the bend of the elbow ; and one or two near the basilic vein, on the inner side of the upper arm, immediately above the elbow. The Deep glands in the fore-arm are excessively small and infre- quent; two or three may generally be found in the course of the ea = a S| : a ' LYMPHATICS OF THE LOWER EXTREMITY. 391 ‘radial and ulnar vessels. In the upper arm there is a chain of small glands, accompanying the brachial artery. The Azillary glands are numerous and of large size. Some are closely adherent 0 the vessels, others are dispersed in the loose areolar tissue of the axilla, and a small chain may be observed extending along the lower border of the pectoralis major to the mammary gland. Two or three subclavian glands are situated beneath the clavicle, and serve as the medium of communication between the axillary and deep cervical lymphatic glands. The Superficial lymphatic vessels of the upper extremity commence upon the fingers and take their course along the fore-arm to the bend of the elbow. The greater part reach their destination by passing along the dorsal surface of the fingers, wrist, and fore-arm, and then curving around the borders of the latter; but some few are met with in the palm of the hand, which take the direction of the median vein. At the bend of the elbow the lymphatics arrange themselves into two groups ; an internal and larger group, which communicates with a gland situated just above the inner condyle, and then accompanies the basilic vein upwards to the axilla to enter the axillary glands; and a small group which follows the course of the cephalic vein. Several of the vessels of this group cross the biceps muscle at its upper part to enter ‘the axillary glands, while the remainder, two or three in number, ascend with the cephalic vein in the interspace of the deltoid and pec- toralis major; they usually join a small gland in this space, and then cross the pectoralis minor muscle to become continuous with the sub- clavian lymphatics. Besides the lymphatic vessels of the arm, the axillary glands receive those from the integument of the chest, its anterior, posterior, and lateral aspect, and the lymphatics of the mammary gland. The Deep lymphatics accompany the vessels of the upper extremity, and communicate occasionally with the superficial lymphatics. They 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 ductus lymphaticus dexter. LYMPHATICS OF THE LOWER EXTREMITY. The Superficial lymphatic glands of the lower extremity are those of the groin, the izguinal ; and one or two situated in the superficial fascia of the posterior aspect of the thigh, just above the popliteal region. ne Inguinal glands are divisible into two groups ; a superior group of small size, situated along the course of Poupart’s ligament, and re- ceiving the lymphatic vessels from the parietes of the abdomen, gluteal region, perineum, and genital organs; and an inferior group of larger glands clustered around the internal saphenous vein near its 392 LYMPHATICS OF THE TRUNK. termination, and receiving the superficial lymphatic vessels from the - lower extremity.. The Deep lymphatic glands are the anterior tibial, popliteal, deep in~ .guinal, gluteal, and ischiatic. The Anterior tibial is generally a single gland, placed on the inter- osseous membrane, by the side of the anterior tibial artery in the upper part of its course. The Popliteal glands, four or five in number and small, are embedded in the loose areolar tissue and fat of the popliteal space. . The Deep inguinal glands, less numerous and smaller than the super- ficial, are situated near the femoral vessels in the groin, beneath the fascia lata. The Gluteal and ischiatic glands are placed near the vessels of that name, above and below the pyriformis muscle at the great ischiatic foramen. The Superficial lymphatic vessels are divisible into two groups, in- ternal and external ; the imternal and principal group commencing on the dorsum and inner side of the foot, ascend the leg by the side of the internal saphenous vein, and passing belsind the inner condyle of the femur, follow the direction of that vein to the groin, where they join the saphenous group of superficial inguinal glands. The greater part of the efferent vessels from these glands pierce the cribriform fascia of the saphenous opening and the sheath of the femoral vessels, to join the lymphatic gland situated in the femoral ring, which serves to establish a communication between the lymphatics of the lower extremity and those of the trunk. The other efferent vessels pierce the fascia lata to join the deep glands. The vessels which pass up- wards from the outer side of the dorsum of the foot, ascend upon the outer side of the leg, and curve inwards just below the knee, to unite with the lymphatics of the inner side of the thigh. The eaternal group consists of a few lymphatic vessels which commence upon the outer side of the foot and posterior part of the ankle, and accompany the external saphenous vein to the popliteal region, where they enter the popliteal glands. The Deep lymphatic vessels accompany the deep veins, and com- municate with the various glands in their course. After joining the deep inguinal glands they pass beneath Poupart’s ligament, to com- municate with the numerous glands situated around the iliac vessels. The deep lymphatics of the gluteal region follow the course of the branches of the gluteal and ischiatic arteries. The former join the glands situated upon the upper border of the pyriformis muscle, and the latter, after communicating with the lymphatics of the thigh, enter the ischiatic glands. LYMPHATICS OF THE TRUNK. The lymphatics of the trunk may be arranged under three heads, superficial, deep, and visceral. ee eT ee Re a ee a LYMPHATICS OF THE TRUNK. 393 The Superficial lymphatic vessels of the upper half of the trunk pass upwards and outwards on each side, and converge, some to the axillary glands, and others to the glands at the root of the neck. The lym- phatics from the mammary glands follow the lower border of the pec- toralis major, communicating, by means of a chain of lymphatic glands, with the axillary glands, The superficial lymphatic vessels of the lower half of the trunk, of the gluteal region, perineum, and external organs of generation, converge to the superior group of superficial inguinal glands. Some small glands are situated on each side of the dorsal vein of the penis, near the suspensory ligament; from these, as from the superficial lymphatics, the efferent vessels pass into the superior group of superficial inguinal glands. . The Deep lymphatic glands of the thorax are the intercostal, inte mammary, anterior mediastinal, and posterior mediastinal. The Jntercostal glands are of small size, and are situated on each side of the vertebral column, near the articulations of the heads of the ribs, and in the course of the intercostal arteries, The Internal mammary glands also very small, are placed in the intercostal spaces, by the side of the internal mammary arteries. The Anterior mediastinal glands occupy the loose areolar tissue of the anterior mediastinum, resting some on the diaphragm, but the greater number upon the large vessels at the root of the heart. The Posterior mediastinal glands are situated along the course of the aorta and cesophagus in the posterior mediastinum, and communicate above with the deep cervical glands, on each side with the intercostal and below with the abdominal glands. The Deep lymphatic vessels of the thorax are the intercostal, internal mammary, and diaphragmatic. The Jntercostal lymphatic vessels follow the course of the arteries of the same name; and reaching the vertebral column curve downwards, to terminate in the thoracic duct. The Internal mammary lymphatics commence in the parietes of the abdomen, communicating with the epigastric lymphatics. They as- cend by the side of the internal mammary vessels, being joined in their course by the anterior intercostals, and terminate at the root of the neck, on the right side in the tributaries of the ductus lymphaticus dexter, and on the left in the thoracic duct. The diaphragmatic lym- phatics pursue the direction of their corresponding veins, and terminate some in front in the internal mammary vessels, and some behind, in the posterior mediastinal lymphatics. The Deep lymphatic glands of the abdomen are the lumbar glands; they are very numerous, and are seated around the common iliac vessels, the aorta and vena cava. The deep lymphatic glands of the pelvis are the external iliac, inter- . nal iliac and sacral. The External iliac are placed around the external iliac vessels, being in continuation by one extremity with the femoral lymphatics, and by the other with the lumbar glands. 394 LYMPHATICS OF THE VISCERA. The Jnternal iliac glands are situated in the course of the internal iliac vessels, and the sacral glands are supported by the concave surface of the sacrum. The Deep lymphatic vessels are continued upwards from the thigh, beneath Poupart’s ligament, and along the external iliac vessels to the lumbar glands, receiving in their course the epigastric, circumflexa ilii, and ilio-lumbar lymphatic vessels. Those from the parietes of the pelvis, and from the gluteal, ischiatic, and obturator vessels, follow the course of the internal iliac arteries, and unite with the lumbar lym- phatics. And the lumbar lymphatic vessels, after receiving all the lymphatics from the lower extremities, pelvis, and loins, terminate by several large trunks in the receptaculum chyli. LYMPHATICS OF THE VISCERA. The Lymphatic vessels of the lungs are of large size, and are distri- buted over every part of the surface, and through the texture of these organs ; they converge to the numerous glands situated around the bifurcation of the trachea and roots of the lungs, the bronchial glands. Some of these glands of small size, may be traced in connection with the bronchial tubes for some distance into the lungs. The efferent vessels from the bronchial glands unite with the tracheal and cesopha- geal glands, and terminate principally in the thoracic duct at the root of the neck, and partly in the ductus lymphaticus dexter. The bron- chial glands, in the adult, present a variable tint of brown, and in old age a deep black colour. In infancy they have none of this pigment, and are not to be distinguished from lymphatic glands in other situa- tions. The Lymphatic vessels of the heart originate in the subserous areolar tissue of the surface, and in the deeper tissues of the organ, and follow the course of the vessels, principally, along the right border of the heart to the glands situated around the arch of the aorta and the bronchial glands, whence they proceed to the root of the neck, and terminate in the thoracic duct. The Pericardiac and thymic lymphatic vessels proceed to join the anterior mediastinal and bronchial glands. The Lymphatic vessels of the liver are divisible into the deep and superficial. The former take their course through the portal canals, and through the right border of the lesser omentum, to the lymphatic glands situated in the course of the hepatic artery and along the lesser curve of the stomach. The superficial lymphatics are situated in the areolar structure of the proper capsule, over the whole surface of the liver. Those of the convex surface are divided into two sets;— . 1. Those which pass from before backwards; 2. Those which advance from behind forwards. The former unite to form trunks, which enter between the folds of the lateral ligaments at the right LACTEALS. 395 and left extremities of the organ, and of the coronary ligament in the middle. Some of these pierce the diaphragm and join the posterior mediastinal glands; others converge to the lymphatic glands situated around the inferior cava. Those which pass from behind forwards consist of two groups: one ascends between the folds of the broad ligament, and perforates the diaphragm, to terminate in the anterior mediastinal glands; the other curves around the anterior margin of the liver to its concave surface, and from thence to the glands in the right border of the lesser omentum. The lymphatic vessels of the concave surface are variously distributed, according to their position ; those from the right lobe terminate in the lumbar glands; those from the gall-bladder which are large and form a remarkable plexus, enter the glands in the right border of the lessér omentum ; and those from the left lobe converge to the lymphatic glands, situated along the lesser curve of the stomach. The Lymphatic glands of the spleen are situated around its hilus, _and those of the pancreas in the course of the splenic vein. The lymphatic vessels of these organs pass through their respective glands, _ and join the aortic glands, previously to terminating in the thoracic duct. _ The Lymphatic glands of the stomach are of small size, and are situated _ along the lesser and greater curves of that organ. The lymphatic vessels, as in other viscera, are superficial and deep, the former originating in _ the subserous and the latter in the submucous tissue ; they pass from _ the stomach in four different directions: some ascend to the glands, situated along the lesser curve, others descend to those occupying the _ greater curve, a third set passes outwards to the splenic glands, and a _ fourth to the glands situated near the pylorus and to the aortic glands. The Lymphatic glands of the small intestine are situated between the _ layers of the mesentery, in the meshes formed by the superior mesen- teric artery, and are thence named mesenteric glands. These glands are most numerous and largest, superiorly, near the duodenum; and, in- feriorly, ‘near the termination of the ileum. The Lymphatic vessels of the small intestines are of two kinds: those of the structure of the intestines, which run upon its surface previ- ously to entering the mesenteric glands; and those which commence in the villi, upon the surface of the mucous membrane, and are named lacteals. The Lacteals, according to Henle, commence in the centre of each villus as a coecal tubulus, which opens into a fine network, situated in the sub-mucous tissue. From this areolar network the lacteal vessels proceed to the mesenteric glands, and from thence to the thoracic duct, in which they terminate. The Lymphatie glands of the large intestines are situated along the attached margin of the intestine, in the meshes formed by the arteries previously to their distribution. The lymphatic vessels take their course in two different directions; those of the coecum, ascending and transverse colon, after traversing their proper glands, proceed to the 396 THORACIC DUCT. mesenteric, and those of the descending colon and rectum to the lum- bar glands. The Lymphatic vessels of the kidney follow the direction of the blood- vessels to the lumbar glands situated around the aorta and inferior vena cava; those of the supra-renal capsules, which are very large and numerous, terminate in the renal lymphatics. The Lymphatic vessels of the viscera of the pelvis terminate in the sacral and lumbar glands. The Lymphatic vessels of the testicle take the course of the spermatic ‘cord in which they are of large size; they terminate in the lumbar glands. THORACIC DUCT. The thoracic duct* commences in the abdomen, by a considerable and somewhat triangular dilatation, the receptaculum chyli, which is situated upon the front of the body of the second lumbar vertebra, behind and between the aorta and inferior vena cava, and close to the tendon of the right crus of the diaphragm. From the upper — part of the receptaculum chyli the thoracic duct ascends through the — aortic opening of the diaphragm, and along the front of the ver- — tebral column, lying between the thoracic aorta and vena azygos, to the fourth dorsal vertebra. It then inclines to the left side, passes behind the arch of the aorta, and ascends by the side of the cesophagus ~ and behind the perpendicular portion of the left subclavian artery — to the root of the neck opposite the seventh cervical vertebra, where — it makes a sudden curve forwards and downwards, and terminates — at the point of junction of the left subclavian with the left internal — jugular vein. The thoracic duct is equal in size to the diameter of a goose- quill at its commencement from the receptaculum chyli, diminishes ~ considerably in diameter towards the middle of the posterior me- diastinum, and again becomes dilated near its termination. At — about the middle of its course it frequently divides into two branches of equal size, which reunite after a short course; and sometimes — it gives off several branches, which assume a plexiform arrangement — in this situation. Occasionally the thoracic duct bifurcates at the upper part of the thorax into two branches, one of which opens — into the point of junction between the right subclavian and jugu- — lar veins, while the other proceeds to the normal termination of the duct on the left side. In rare instances the duct has been ~ found to terminate in the vena azygos, which is its normal desti- — nation in some Mammaiia. The thoracic duct presents fewer valves in its course than lym- — * The thoracic duct was discovered by Eustachius, in 1563, in the horse : he i HE 'S - ? ‘ * The course and termination of the thoracic duct. 1. The arch of the aorta. 2. The thoracic aorta. 3. The abdominal aorta; shewing its principal branches divided near their origin. 4. The arteria innominata, dividing into the right carotid and right subclavian arteries. 5. The left carotid. 6. The left subclavian. 7. The supericr cava, formed by the union of 8, the two venze innominate ; and these by the junction 9, of the internal jugular and subcla- vian vein at each side. 10. The greater vena azygos. 11. The termination of the lesser in the greater vena azygos. 12. The receptaculum chyli; several lymphatic trunks are seen opening into it. 13. The thoracic duct, dividing opposite the middle of the dorsal vertebree into two branches which soon re- unite; the course of the duct behind the arch of the aorta and left subclavian * 398 THORACIC DUCT. right subclavian with the right internal jugular vein, at the point where these veins unite to form the right vena innominata. It is pro- vided at its termination with a pair of semilunar valves, which prevent the entrance of blood from the veins. artery is shewn by a dotted line. 14. The duct making its turn at the — root of the neck and receiving several lymphatic trunks previously to termi- nating in the posterior aspect of the junction of the internal jugular and sub- rissldomg vein, 15, The termination of the trunk of the ductus lymphaticus exter, few fue fa A 4 4 ie ask Te ees aE i PN ine ks Pant See RE ee Eo eee ae 399 CHAPTER VIII. ON THE NERVOUS SYSTEM. _ THE nervous system consists of a central organ, the cerebro-spinal centre or axis, and of numerous rounded and flattened white cords, the nerves, which are connected by one extremity with the cerebro- spinal centre, and by the other are distributed to all the textures of the body.. The sympathetic system is an exception to this description ; for in place of one it has many small centres which are called ganglia, and which communicate very freely with the cerebro-spinal axis an with its nerves. ad __ The cerebro-spinal axis consists of two portions, the brain, an organ of large size, situated within the skull, and the spinal cord, a length- ened portion of the nervous centre continuous with the brain, and g occupying the canal of the vertebral column. The most superficial examination of the brain and spinal cord shews them to be composed of fibres, which in some situations are ranged side by side or collected into bundles or fasciculi, and in. other situations are interlaced at various angles by cross fibres. The fibres are con- nected and held together by a delicate areolar web, which forms the bond of support to the entire organ. It is also observed that the cerebro-spinal axis presents two substances differing from each other in density and colour ; a grey or cineritious or cortical substance, and awhite or medullary substance. The grey substance forms a thin lamella over the entire surface of the convolutions of the cerebrum, and the laminz of the cerebellum: hence it has been named cortical ; but the grey substance is not confined to the surface of the brain, as this term would imply ; it is likewise situated in the centre of the spinal cord its entire length, and may be thence traced through the medulla oblongata, crura cerebri, thalami optici, and corpora striata ; it enters also into the composition of the locus perforatus, tuber cinereum, com- missura mollis, pineal gland, pituitary gland, and corpora rhomboidea. The fibres of the cerebro-spinal axis are arranged into two classes, diverging and converging. The diverging fibres proceed from the medulla oblongata, and diverge to every part of the surface of the brain; while the converging commence upon the surface, and proceed inwards towards the centre so as to connect the diverging fibres of op’ posite sides. In certain parts of their course the diverging fibres’ are’ separated by the grey substance, and increase in number so as to form a body of considerable size, which is called a ganglion.. The position 400 NERVOUS SYSTEM.—DEVELOPMENT. and mutual relations of these fibres and ganglia may be best explained by reference to the mode of development of the cerebro-spinal axis in . animals and in man. The centre of the nervous system in the lowest animals possessed of a lengthened axis, presents itself in the form of a double cord. a » AL TN “Gil ORG TNI Pel, ili, \\ > “Vi i mH z SN ry \\ SN . N \ y * The isthmus encephali, shewing the thalamus opticus, corpora quadri- gemina, pons Varolii, and medulla oblongata as viewed from the side. 1. The thalamus opticus. 2. The posterior prominence of this body, tuberculum supe- rius posterius or pulvinar. 3. The corpus geniculatum externum. 4. The corpus geniculatum internum. 5. The commencement of the tractus opticus. 6. The pineal gland. 7. The nates. 8. The testis of one side. 9. The bra- MOTORES OCULORUM. 437 of the thalamus opticus and from the nates. Proceeding from this origin it winds around the crus cerebri as a flattened band, under the name of tractus opticus, and joins with its fellow in front of the tuber cinereum to form the optic commissure (chiasma). The tractus opticus is united with the crus cerebri and tuber cinereum, and is covered in by the pia mater ; the commissure is also connected with the tuber cinereum, from which it receives fibres, and the nerve beyond the commissure diverges from its fellow, becomes rounded in form, and is enclosed in a sheath derived from the arachnoid. In passing through the optic foramen the optic nerve receives a sheath from the dura mater, which splits at this point into two layers; one, which becomes the periosteum of the orbit ; the other, the one in question, which forms the sheath for the nerve, and is lost in the sclerotic coat of the eyeball. After a short course within the orbit the optic nerve pierces the sclerotic and choroid coats and expands into the nervous membrane of the eyeball, the retina. Near the globe, the nerve is pierced by a small artery, the arteria centralis retinze, which runs through the central axis of the nerve and reaches the internal surface of the retina, to which it distributes branches. The commissure rests upon the processus olivaris of the sphenoid bone ; it is bounded by the lamina cinerea of the corpus callosum in front, by the substantia perforata on each side, and by the tuber cinereum behind. Within the commissure the innermost fibres of the optic nerves cross each other to pass to opposite eyes, while the outer fibres continue their course uninterruptedly to the eye of the corresponding side. The neurilemma of the commissure, as well as that of the nerves, is formed by the pia mater. THIRD PAIR. MotTores OcuLorum. — The motor oculi, a nerve of moderate size, arises from the inner side of the crus crebri, close to the pons Varolii, and passes forward between the posterior cerebral and superior cerebellar artery. It pierces the dura mater imme- diately in front of the posterior clinoid process ; descends obliquely chium anterius of the corpora quadrigemina. a. Their brachium posterius. 6. The origin of the fourth nerve, which may be seen descending over the crus cerebri. ce. The processus e cerebello ad testem, or superior peduncle of the cerebellum. d. The band of fibres termed laqueus, the superior division of the fasciculus olivaris crossing the superior peduncle of the cerebeilum to enter the corpora quadrigemina. ‘Through the small triangular space in front of this band, crossed by the fourth nerve, some of the fibres of the superior peduncle of the cerebellum may be seen. e. The superior portion of 9 crus cerebri, termed tegmentum. /f. Its inferior portion. g. The third nerve. h. The pons Varolii. 7%. The crus cerebelli, or middle peduncle of the cerebellum. &. The inferior peduncle derived from the corpus restiforme. The mass lying in the angular interval upon these is the superior peduncle. /. The fifth nerve issuing from between the transverse fasciculi of the pons Varolii. m. The sixth nerve. #. The seventh nerve; the inferior and smaller cord is the facial nerve, the superior and larger the auditory. o. The corpus olivare crossed in- feriorly by the superficial arciform fibres. py. The corpus pyramidale. g. The median posterior fasciculi of the medulla oblongata. 7. The corpus restiforme. s. The spmal cord. ¢. The fourth ventricle. 438 PATHETIC.—TRIFACIAL. along the external wall of the cavernous sinus ; and divides into two . branches which enter the orbit between the two heads of the external rectus muscle. The superior branch ascends, and supplies the superior rectus and levator palpebrae. The inferior sends a branch beneath the optic nerve to the internal rectus, another to the inferior rectus, and a long branch to the inferior oblique muscle. From the latter a short thick branch is given off to the ciliary ganglion, forming its inferior root. The fibres of origin of this nerve may be traced into the grey sub- stance of the crus cerebri,* into the motor tract,t and as far as the superior fibres of the crus cerebri.t In the cavernous sinus it receives one or two filaments from the cavernous plexus, and one from the ophthalmic nerve. FourtH parr. Partuerict (trochlearié).— The fourth is the smallest cerebral nerve ; it arises from the valve of Vieussens close to the testis, and winding around the crus cerebri to the extremity of the petrous portion of the temporal bone, pierces the dura mater near the oval opening for the fifth nerve, and passes along the outer wall of the cavernous sinus to the sphenoidal fissure. In its course through the sinus it is situated at first below the motor oculi, but afterwards ascends and becomes the highest of the nerves which enter the orbit through the sphenoidal fissure. Upon entering the orbit the nerve crosses the levator palpebree muscle near its origin, and is distributed _ upon the orbital surface of the superior oblique or trochlearis muscle ; hence its synonym trochlearis. Branches. —While in the cavernous sinus the fourth nerve gives off a recurrent branch, some filaments of communication to the ophthalmic nerve, and a branch to assist in forming the lachrymal nerve ; the recurrent branch, which consists of sympathetic filaments derived from the carotid plexus, passes backwards between the layers of the tento- rium, and divides into two or three filaments, which are distributed to the lining membrane of the lateral sinus. This nerve is sometimes a branch of the ophthalmic, and occasionally proceeds directly from the carotid plexus. Firrn parr. Triracta (trigeminus).—The fifth nerve, the great sensitive nerve of the head and face, and the largest cranial nerve, is analogous to the spinal nerves in its origin by two roots, from the anterior and posterior columns of the spinal cord, and in the existence of a ganglion on the posterior root. It arises § from a tract of yel- lowish white matter situated in front of the floor of the fourth ven- tricle and the origin of the auditory nerve, and behind the crus cerebelli. This tract divides inferiorly into two fasciculi which may be traced downwards into the spinal cord, one being continuous with * Mayo. + Solly. t Grainger. Ea § I have adopted the origin of this nerve, given by Dr. Alcock, of Dublin, as the result of his dissections, in the Cyclopeedia of Anatomy and Physiology. Mr. Mayo also traces the anterior root of the nerve to a similar origin. OPHTHALMIC NERVE. ; 439 the fibres of the anterior column, the other with the posterior column. Proceeding from this origin the two roots of the nerve pass forward, and issue from the brain upon the anterior part of the crus cerebelli, where they are separated by a slight interval. The anterior is much smaller than the posterior, and the two together constitute the fifth nerve, which in this situation consists of seventy to a hundred fila- ments held together by pia mater. The nerve then passes through an oval opening in the border of the tentorium, near the extremity of the petrous bone, and spreads out into a large semilunar ganglion, the Casserian. If the ganglion be turned over, it will be seen that the anterior root lies against its under surface without having any connection with it, and may be followed onwards to the inferior maxillary nerve. The Casserian ganglion divides into three branches, the ophthalmic, superior maxillary, and inferior maxillary. _ The OPHTHALMIC NERVE is a short trunk, being not more than three quarters of an inch in length ; it arises from the upper angle of the Casserian ganglion, beneath the dura mater, and passes forwards through the outer wall of the cavernous sinus, lying externally to the other nerves; it divides into three branches. Previously to its divi- sion it receives several filaments from the carotid plexus, and gives off a small recurrent nerve, that passes backwards with the recurrent branch of the fourth nerve between the two layers of the tentorium to the lining membrane of the lateral sinus. The Branches of the ophthalmic nerve are, the — Frontal, Lachrymal, Nasal. The Frontal nerve mounts above the levator palpebree, and runs forward, resting upon that muscle, to the supra-orbital foramen, through which it escapes upon the forehead, with the supra-orbital artery. It supplies the conjunctiva and upper eyelid and the integument of the cranium as far as the vertex. The frontal nerve gives off but one small branch, the supra-troch- lear, which passes inwards above the pulley of the superior oblique muscle, and ascends along the middle line of the forehead, distributing filaments to the integument, to the inner angle of the eye and root of the nose, and to the conjunctiva. The Lachrymal nerve, the smallest of the three branclies of the ophthalmic, receives a filament from the fourth nerve in the cavernous sinus, and passes outwards along the upper border of the external rectus muscle, and in company with the lachrymal artery, to the lachrymal gland, where it divides into two branches. The superior branch passes along the upper surface of the gland and through a foramen in the malar bone, and is distributed upon the temple and cheek, communicating with the subcutaneus male and facial nerves. 440 FIFTH PAIR OF NERVES. Fig. 145.* The inferior branch supplies the lower surface of the gland and con- junctiva, and terminates in the integument of the upper lid communi- cating with the facial nerve. The Nasal nerve (naso-ciliaris) passes forwards between the two * A diagram, shewing the fifth pair of nerves with its branches. 1. The oe of the nerve by two roots. 2. The nerve escaping from the crus cere- belli. 3. The Casserian ganglion. 4. Its ophthalmic divisién. 5. The frontal nerve, giving off the supra-trochlear branch, and escaping on the forehead through the supra-orbital foramen. 6. The lachrymal nerve. 7. The nasal nerve, passing at 8 through the anterior ethmoidal foramen, and giving off the infra-trochlear branch. 9. The communication of the nasal nerve with the ciliary ganglion. 10. Asmall portion of the third nerve with which the gan- glion is seen communicating ; the ganglion gives off the ciliary branches from its anterior aspect. 11. The superior maxillary nerve. 12. Its orbital branch. 13. The two branches communicating with Meckel’s ganglion; the three branches given off from the lower part of the ganglion are the posterior palatine nerves. 14, 14. The superior dental nerves, posterior, middle, and anterior, forning Oe their communications the superior maxillary plexus. 15 The infra- orbital branches distributed upon the cheek. 16. The inferior maxillary nerve. 17. Its anterior or muscular trunk. 18. The posterior trunk ; the two divisions are separated by an arrow. 19 The gustatory nerve. 20. The chorda tym- pani joining it at an acute angle. 21. The submaxillary ganglion. 22. The inferior dental nerve. 23. Its mylohyoidean branch. 24. The auricular nerve, dividing behind the articulation of the lower jaw, to reunite and form a single trunk. 25. Its branch of communication with the facial nerve. 26. Its tem- poral branch. SUPERIOR MAXILLARY NERVE, 44] heads of the external rectus muscle, crosses the optic nerve in com- pany with the ophthalmic artery, and enters the anterior ethmoidal foramen immediately above the internal rectus. It then traverses the upper part of the ethmoid bone to the cribriform plate, and passes downwards through the slit-like opening by the side of the crista galli into the nose, where it divides into two branches — an internal branch supplying the mucous membrane, near the anterior openings of the nares ; and an eaternal branch which passes between the fibro-carti- lages, and is distributed to the integument at the extremity of the nose. The Branches of the nasal nerve within the orbit are, the gangli- onic, ciliary, and infra-trochlear ; in the nose it gives off one or two filaments to the anterior ethmoidal cells and frontal sinus. The ganglionic branch passes obliquely forwards to the superior angle of the ciliary ganglion, forming its superior or long root. The ciliary branches are two or three filaments which are given off by the nasal as it crosses the optic nerve. They pierce the posterior part of the sclerotic, and pass between that tunic and the choroid to be distributed to the iris. The infra-trochlear is given off just as the nerve is about to enter the anterior ethmoidal foramen. It passes along the superior border of the internal rectus to the inner angle of the eye, where it ~ communicates with the supra-trochlear nerve, and supplies the lachry- mal sac, caruncula lachrymalis, conjunctiva, and inner angle of the orbit. The SupERIOR MAXILLARY NERVE, larger than the preceding, pro- ceeds from the middle of the Casserian ganglion; it passes forwards through the foramen rotundum, crosses the spheno-maxillary fossa, and enters the canal in the floor of the orbit, along which it runs to the infra-orbital foramen. Emerging on the face, beneath the levator labii superioris muscle, it divides into a number of branches, which are dis- tributed to the lower eyelid and conjunctiva, and to the muscles and integument of the upper lip, nose, and cheek, forming a plexus with the facial nerve. The Branches of the superior maxillary nerve are divisible into three groups:—1. Those which are given off in the spheno-maxillary fossa. 2. Those in the infra-orbital canal; and 3. Those on the face. They may be thus arranged :— Orbital, Spheno-maxillary fossa, 1% from Meckel’s ganglion, Posterior dental. ; Middle dental, Anterior dental. Muscular, Cutaneous. Infra-orbital canal, On the face, The Orbital branch (n. subcutaneus mal) enters the orbit through 442 INFERIOR MAXILLARY NERVE. the spheno-maxillary fissure, and divides into two branches, temporal ‘and malar; the temporal branch ascends along the outer wall of the orbit, and, after receiving a branch from the lachrymal nerve, passes through a canal in the malar bone and enters the temporal fossa; it then pierces the temporal muscle and fascia and is distributed to the integument of the temple and side of the forehead, communicating with the facial and anterior auricular nerve. In the temporal fossa it com- municates with the deep temporal nerves. The malar, or inferior branch, takes its course along the lower angle of the outer wall of the orbit, and emerges upon the cheek through an opening in the malar bone, passing between the fibres of the orbicularis palpebrarum muscle. It communicates with branches of the infra-orbital and facial nerves. The Two branches from Meckel’s ganglion ascend from that body to join the nerve, as it crosses the spheno-maxillary fossa. The Posterior dental branches pass through small foramina, in the posterior surface of the superior maxillary bone, and running forwards in the base of the alveolus, supply the posterior teeth and gums. The Middle and anterior dental branches descend to the correspond- ing teeth and gums; the former beneath the lining membrane of the antrum, the latter through distinct canals in the walls of the bone. Previously to their distribution, the dental nerves form a plexus (supe- rior maxillary plexus) in the outer wall of the superior maxillary bone immediately above the alveolus. From this plexus the filaments are given off which supply the pulps of the teeth, the gums, the mucous membrane of the floor of the nares, and the palate. Some gangliform masses have been described in connection with this plexus, one being placed over the canine, and another over the second molar tooth. The Muscular and cutaneous branches are the terminating filaments of the nerve; they supply the muscles, integument, and mucous mem- brane of the cheek, nose, and lip, and form an intricate plexus with branches of the facial nerve. The INFERIOR MAXILLARY NERVE proceeds from the inferior angle of the Casserian ganglion; it is the largest of the three divisions of the fifth nerve, and is augmented in size by the anterior or motor root, which passes behind the ganglion, and unites with the inferior maxillary as it escapes through the foramen ovale. Emerging at the foramen ovale the nerve divides into two trunks, external and in- ab which are separated from each other by the external pterygoid muscle, The External trunk, into which may be traced nearly the whole of the motor root, immediately divides into five branches which are dis- tributed to the muscles of the temporo-maxillary region; they are— The Masseteric, which crosses the sigmoid notch with the masseteric artery to the masseter muscle. It sends a small branch to the tem- poral muscle, and a filament to the temporo-maxillary articulation. Temporal ; two branches passing between the upper border of the external pterygoid muscle and the temporal bone to the temporal GUSTATORY NERVE-—INFERIOR DENTAL NERVE. 443 muscle. Two or three filaments from these nerves pierce the temporal fascia, and communicate with the lachrymal, sub-cutaneus malee, auri- cular and facial nerve. Buccal; a large branch which pierces the fibres of the external pterygoid, to reach the buccinator muscle. This nerve sends fila- ments to the temporal and external pterygoid muscle, to the mucous membrane and integument of the cheek, and communicates with the facial nerve. Internal pterygoid ; a long and slender branch, which passes inwards to the internal pterygoid muscle, and gives filaments in its course to the tensor palati and tensor tympani. This nerve is remarkable from its connection with the otic ganglion, to which it is closely at- tached. The Internal trunk divides into three branches— Gustatory, Inferior dental, Anterior auricular. The GusTaTORY NERVE descends between the two pterygoid muscles to the side of the tongue, where it becomes flattened, and divides into numerous filaments, which are distributed to the papillee - and mucous membrane. Relations.—It lies at first between the external pterygoid muscle and the pharynx, next between the two pterygoid muscles, then be- tween the internal pterygoid and ramus of the jaw, and between the stylo-glossus muscle and the submaxillary gland ; lastly, it runs along the side of the tongue, resting upon the hyo-glossus muscle, and covered in by the mylo-hyoideus and mucous membrane. The gustatory nerve, while between the two pterygoid muscles, receives a branch from the inferior dental ; lower down it is joined at an acute angle by the chorda tympani which passes downwards in the sheath of the gustatory to the submaxillary gland, where it unites with the submaxillary ganglion. On the hyo-glossus muscle some branches of communication are sent to the hypoglossal, and in the course of the nerve seyeral small branches to the mucous membrane of the fauces, to the tonsils, submaxillary gland, Wharton’s duct, and sublingual gland. The INFERIOR DENTAL NERVE passes downwards with the inferior dental artery, at first between the two pterygoid muscles, and then between the internal lateral ligament and the ramus of the lower jaw, to the dental foramen. It then runs along the canal in the inferior maxillary bone, distributing branches (inferior maxillary plexus) to the teeth and gums, and divides into two terminal branches, incisive and mental, The zncisive branch passes forwards, to supply the incisive teeth: the mental branch escapes through the mental foramen, to be distributed to the muscles and integument of the chin and lower lip, and to the mucous membrane of the latter, communicating with the facial nerve. 444 AURICULAR NERVE.—ABDUCENS. The inferior dental nerve gives off but one branch, the mylo-hyoidean, which leaves the nerve just as it is about to enter the dental foramen, This branch pierces the insertion of the internal lateral ligament, and descends along a’ groove in the bone to the inferior surface of the raylo- hyoid muscle, to which, and to the anterior belly of the digastricus, it is distributed. The ANTERIOR AURICULAR NERVE originates by two roots, be- tween which the arteria meningea media takes its course, and passes directly backwards behind the articulation of the lower jaw, against which it rests. In this situation it divides into two branches, which reunite, and form a kind of plexus. From the plexus two branches are given off—ascending and descending. The ascending or temporal branch sends one or two considerable branches of communication to the facial nerve, and then ascends in front of the ear to the temporal re- gion, upon which it is distributed in company with the branches of the temporal artery. In its course it sends filaments to the temporo-max- illary articulation, to the pinna and meatus of the ear, and to the in- tegument in the temporal region. It communicates on the temple with branches of the facial, supra-orbital, lachrymal, and subcutaneus malz nerve. The descending branch enters the parotid gland, to which it sends numerous branches; it communicates with the inferior dental and auricularis magnus nerve, and supplies the external ear, the mea- tus auditorius, and the temporo-maxillary articulation, and sends one or two filaments into the tympanum. SIXTH PAIR. ABDUCENTES.—The abducens nerve, about half the size of the motor oculi, arises by several filaments from the upper con- stricted part of the corpus pyramidale close to the pons Varolii. Proceeding forwards from this origin it lies parallel with the basilar artery, and, piercing the dura mater upon the clivus Blumenbachii of the sphenoid bone, ascends beneath that membrane to the cavernous sinus. It then runs forwards along the inner wall of the sinus below the other nerves, and, resting against the internal carotid artery, passes between the two heads of the external rectus, and is distributed to that muscle. As it enters the orbit, it lies upon the ophthalmic vein, from which it is separated by a lamina of dura mater. In the cavern- ous sinus it is joined by several filaments from the carotid plexus, by one from Meckel’s ganglion, and one from the ophthalmic nerve. Mr. _ Mayo traced the origin of this nerve between the fasciculi of the cor- pora pyramidalia to the posterior part of the medulla oblongata; and Mr. Grainger pointed out its connection with the grey substance of the spinal cord. SEVENTH PAIR.—The seventh pair consists of two nerves which lie side by side on the posterior border of the crus cerebelli. The smaller and most internal of these, and, at the same time, the most dense in texture, is the facial nerve or portiodura. The external nerve, which is soft and pulpy, and often grooved by contact with the preceding, is FACIAL NERVE. 445 the auditory nerve or portio mollis of the seventh pair. Soemmering makes the auditory nerve the eighth pair; but, retaining the classifi- eation of Willis, we regard it as a part of the seventh with the facial. FAcIAL NERVE. (portio dura).—The facial nerve arises from the upper part of the groove between the corpus olivare and corpus resti- forme, close to the pons Varolii, from which point its fibres may be traced deeply into the corpus restiforme. The nerve then passes for- wards, resting upon the crus cerebelli, and comes into relation with the anditory nerve, with which it enters the meatus auditorius internus, lying at first to the inner side of, and then upon that nerve. At the bottom of the meatus it enters the canal expressly intended for it, the aqueductus Fallopii, and directs its course forwards towards the hiatus Fallopii, where it forms a gangliform swelling (intumescentia gangli- formis), and receives the petrosal branch of the Vidian nerve. It then curves backwards towards the tympanum, and descends along the inner wall of that cavity to the stylo-mastoid foramen. Emerging at the stylo-mastoid foramen it passes forwards within the parotid gland, crossing the external jugular vein and external carotid artery, and at the ramus of the lower jaw divides into two trunks, temporo-facial and cervico-facial. These trunks at once split into numerous branches which, after forming a number of looped communications (pes anseri- nus) with each other over the masseter muscle, spread out upon the side of the face, from the temple to the neck, to be distributed to the muscles of this extensive region. The communications which the facial nerve maintains in its course are the following: in the meatus audito- rius, it sends one or two filaments to the auditory nerve; the intu- mescentia gangliformis receives the nervus petrosus superficialis major and minor, and sends a twig back to the auditory nerve; behind the tympanum the nerve receives one or two twigs from the auricular branch of the pneumogastric ; at its exit from the stylo-mastoid fora- men it receives a twig from the glosso-pharyngeal, and in the parotid gland one or two large branches from the anterior auricular nerve. Besides these, the facial nerve has numerous peripheral communica- tions, with the branches of the fifth nerve on the face, and of the cer- vical nerves in the parotid gland and neck. The numerous communi- cations of the facial nerve obtained for it the designation of nervus sympatheticus minor. The Branches of the facial nerve are— Within the aqueductus § Tympanic, Fallopii. d Chorda tympani. After emerging at the Style pa theviars stylo-mastoid foramen, Digastric 2 Temporo-facial, On the face, } Cervico-facial. 446 FACIAL NERVE. Fig. 146.* erica wee. \ 3 i The Tympanic branch is a small filament distributed to the stapedius muscle. The Chorda tympani quits the facial just before that nerve emerges from the stylo-mastoid foramen, and ascends by a distinct canal to the upper part of the posttrior wall of the tympanum, where it enters * The distribution of the faciai nerve and the branches of the cervical plexus. 1. The facial nerve, escaping from the stylo-mastoid foramen, and crossing the ramus of the lower jaw; the parotid gland has been removed in order to see the nerve more distinctly. 2. The posterior auricular branch; the digastric and stylo-mastoid filaments are seen near the origin of this branch. 3. Temporal branches, communicating with (4) the branches of the frontal nerve. 5. Facial branches, communicating with (6) the infra-orbital nerve. 7. Facial branches, communicating with (8) the mental nerve. 9. Cervico-facial branches, com- municating with (10) the superficialis colli nerve, and forming a plexus (11) over the submaxillary gland. The distribution of the branches of the facial in a radiated direction over the side of the face and their looped communications constitute the pes anserinus. 12. The auricularis magnus nerve, one of the ascending branches of the cervical plexus. 13. The occipitalis minor, ascend- ing along the posterior border of the sterno-mastoid muscle. 14. The super- ficial and deep descending branches of the cervical plexus. 15. The spinal accessory nerve, giving off a branch to the external surface of the trapezius muscle. 16. The occipitalis major nerve, the posterior branch of the second cervical nerve. ; | / | te , — ee ee ee se ve a AUDITORY NERVE. 447 that cavity through an opening situated between the base of the pyra- mid and the attachment of the membrana tympani, and becomes in- vested by mucous membrane. It then crosses the tympanum between the handle of the malleus and long process of the incus to the anterior inferior angle of the cavity, and escapes through a distinct opening in the fissura Glaseri, and joins the gustatory nerve at an acute angle be- tween the two pterygoid muscles. Enclosed in the sheath of the gus- tatory nerve, it descends to the submaxillary gland, where it unites with the submaxillary ganglion. The Posterior auricular nerve ascends behind the ear, between the meatus and mastoid process, and divides into an anterior and a poste- rior branch. The anterior branch receives a filament of communication from the auricular branch of the pneumogastric nerve, and distributes filaments to the retrahens and attollens aurem muscles and to the pinna. The posterior branch communicates with the auricularis magnus and occipitalis minor, and is distributed to the posterior belly of the occi- pito-frontalis, The Stylo-hyoid branch is distributed to the stylo-hyoid muscle. The Digastric branch supplies the posterior belly of the digastricus muscle, and communicates with the glosso-pharyngeal and pneumogas- tric nerve. _ The Temporo-facial gives off a number of branches which are dis- tributed over the temple and upper half of the face, supplying the muscles of this region, and communicating with the branches of the auricular, the subcutaneus male, and the supra-orbital nervee The inferior branches, which accompany Stenon’s duct, and form a plexus with the terminal branches of the infra-orbital nerve. The Cervico-facial divides into a number of branches that are dis- tributed to muscles on the lower half of the face and upper part of the neck. The cervical branches form a plexus with the superficialis colli nerve over the submaxillary gland, and are distributed to the pla- tysma myoides. AUDITORY NERVE (portio mollis).—The auditory nerve takes its origin in the lineze transversze (strize medullares) of the anterior wall or floor of the fourth ventricle, and winds around the corpus restiforme, from which it receives fibres, to the posterior border of the crus cere- belli. It then passes forwards upon the crus cerebelli in company with the facial nerve, which lies in a groove on its superior surface, and enters the meatus auditorius internus, and at the bottom of the meatus it divides into two branches, cochlear and vestibular. The au- ditory nerve is soft and pulpy in texture, and receives in the meatus auditorius several filaments from the facial nerve. E1cHtTu pair,—The eighth pair consists of three nerves, glosso- pharyngeal, pneumogastric, and spinal accessory ; these are the ninth, tenth, and eleventh pairs of Soemmering. GLOSSO-PHARYNGEAL NERVE.—The glosso-pharyngeal nerve arises 448 GLOSSO-PHARYNGEAL NERVE. by five or six filaments from the groove between the corpus olivare and _restiforme, and escapes from the skull at the innermost extremity of the jugular foramen threugh a distinct opening in the dura mater, lying an- teriorly to the sheath of the pneumogastric and spinal accessory nerves, and internally to the jugular vein. It then passes forwards between the jugular vein and internal carotid artery, to the stylo-pharyngeus muscle, and descends along the inferior border of that muscle to the hyo-glossus, beneath which it curves to be distributed to the mucous membrane of the base of the tongue and fauces, to the mucous glands of the mouth, and to the tonsils. While situated in the jugular fossa, the nerve presents two gangliform swellings; one superior (ganglion jugulare of Muller) of small size, and involving only the posterior fibres of the nerve; the other inferior, nearly half an inch below the prece- ding, of larger size and occupying the whole diameter of the nerve, the ganglion of Andersch* (ganglion petrosum). The fibres of origin of this nerve may be traced through the fasciculi of the corpus restiforme to the grey substance in the floor of the fourth ventricle. The Branches of the glosso-pharyngeal nerve are— Communicating branches with the Facial, Pneumogastric, Spinal accessory, Sympathetic. Tympanic, Muscular, Pharyngeal, Lingual, Tonsillitic. The Branches of communication proceed from the ganglion and from the upper part of the trunk of the nerve, and are common to the facial, eighth pair, and sympathetic; they form a complicated plexus at the base of the skull. The Tympanie branch (Jacobson’s nerve) proceeds from the ganglion of Andersch, or from the trunk of the nerve immediately above the ganglion: it enters a small bony canal in the jugular fossa (page 34) and divides into six branches, which are distributed upon the inner wall of the tympanum, and establish a plexiform communication (tym- panic plexus) with the sympathetic and fifth pair of nerves. The branches of distribution supply the fenestra rotunda, fenestra ovalis, and Eustachian tube: those of communication join the carotid plexus, _ the petrosal branch of the Vidian nerve, and the otic ganglion. \ __* Charles Samuel Andersch. ‘‘ Tractatus Anatomico-Physiologicus de Nervis Corporis Humani Aliquibus, 1797.’? PNEUMOGASTRIC NERVE. 449 The Muscular branch divides into filaments, which are distributed to the stylo-pharyngeus and to the posterior belly of the digastricus and stylo-hyoideus muscle. The Pharyngeal branches are two or three filaments which are distributed to the pharynx and unite with the pharyngeal branches of the pneumogastric and sympathetic nerve to form the pharyngeal plexus. The Lingual branches enter the substance of the tongue beneath the hyo-glossus and stylo-glossus muscle, and are distributed to the mu- cous membrane of the side and base of the tongue, and to the epi- glottis and fauces. The Tonsillitie branches proceed from the glosso-pharyngeal nerve near its termination ; they form a plexus (circulus tonsillaris) around the base of the tonsil, from which numerous filaments are given off to the mucous membrane of the fauces and soft palate, communicating with the posterior palatine branches of Meckel’s ganglion. PNEUMOGASTRIC NERVE (vagus).—The pneumogastric nerve arises by ten or fifteen filaments from the groove between the corpus olivare and corpus restiforme, immediately below the glosso-pharyngeal, and passes out of the skull through the inner extremity of the jugular fora- _ Inen in a distinct canal of the dura mater. While situated in this canal it presents a small rounded ganglion (ganglion jugulare) ; and having escaped from the skull, a gangliform swelling (plexus gangli- formis), nearly an inch in length, and surrounded by an irregular plexus of white nerves, which communicate with each other, with the other divisions of the eighth pair, and with the trunk of the pneumo- gastric below the ganglion. The plexus gangliformis (ganglion of the superior laryngeal branch, of Sir Astley Cooper), is situated, at first, behind the internal carotid artery, and then between that vessel and the internal jugular vein. The pneumogastric nerve then descends the neck within the sheath of the carotid vessels, lying behind and be- tween the artery and vein, to the root of the neck. Here the course of the nerve at opposite sides becomes different. On the right side it passes between the subclavian artery and vein to the posterior mediastinum, then behind the root of the lung to the cesophagus, which it accompanies to the stomach, lying on its posterior aspect. ‘On the left it enters the chest parallel with the left subclavian ar- tery, crosses the arch of the aorta, and descends behind the root of the lung, and along the anterior surface of the cesophagus, to the stomach. The fibres of origin of the pneumogastric nerve, like those of the glosso-pharyngeal, may be traced through the fasciculi of the corpus restiforme into the grey substance of the floor of the fourth ventricle. 450 PNEUMOGASTRIC NERVE. The Branches of the pneumogastric nerve are the following:— Communicating branches with the Facial, Glosso-pharyngeal, © Spinal accessory, Hypo-glossal, Sympathetic. Auricular, Pharyngeal, Superior laryngeal, Cardiac, Inferior or recurrent laryngeal, Pulmonary anterior, Pulmonary posterior, (Esophageal, Gastric. The Branches of communication form part of the complicated plexus at the base of the skull. The branches to the ganglion of Andersch are given off by the superior ganglion in the jugular fossa. The Awricular nerve is given off from the lower part of the jugu- lar ganglion, or from the trunk of the nerve immediately below, and receives immediately after its origin a small branch of communication from the glosso-pharyngeal. It then passes outwards behind the jugu- lar vein, and on the outer side of that vessel enters a small canal (page 34) in the petrous portion of the temporal bone near the stylo- mastoid foramen. Guided by this canal it reaches the descending part of the aqueductus Fallopii and joins the facial nerve. In the aque- ductus Fallopii the auricular nerve gives off two small filaments, one of which communicates with the posterior auricular branch of the facial, while the other is distributed to the pinna, _ The Pharyngeal nerve arises from the pneumogastric, immediately above the gangliform plexus, and descends behind the internal carotid artery to the upper border of the middle constrictor, upon which it forms the pharyngeal plexus assisted by branehes from the glosso- pharyngeal, superior laryngeal, and sympathetic. The pharyngeal plexus is distributed to the muscles and mucous membrane of the pharynx. The Superior laryngeal nerve arises from the gangliform plexus of the pneumogastric, of which it appears to be almost a continua- tion; hence this plexus was named by Sir Astley Cooper the “ gan- glion of the superior laryngeal branch.” The nerve descends behind the internal carotid artery to the opening in the thyro-hyoidean membrane, through which it passes with the superior laryngeal artery, and is distributed to the mucous membrane of the larynx and aryte- noideus muscle. On the latter, and behind the cricoid cartilage, it communicates with the recurrent laryngeal nerve. Behind the internal carotid it gives off the eaternal laryngeal branch, which sends a twig SUPERIOR LARYNGEAL NERVE.. to the pharyngeal plexus, and then descends to supply the in- ferior constrictor and crico-thy- roid muscles and thyroid gland. This branch communicates infe- riorly with the recurrent laryn- geal and sympathetic nerve. Mr. Hilton of Guy’s Hospi- tal, concludes from his dissec- tions+ that the superior laryn- geal nerve is the nerve of sensa- tzon to the larynx, being distri- buted solely (with the exception of its external laryngeal branch and a twig to the arytenoideus) to the mucous membrane. If this fact be taken in connection with the observations of Sir Astley Cooper, and the dissec- tions of the origin of the nerve by Mr. Edward Cock, we shall have ample evidence, both in the ganglionic origin of the * Origin and distribution of the eighth pair of nerves. 1.3, 4. The medulla oblongata. 1. Is the cor- pus pyramidale of one side. 3. The corpus olivare. 4. The corpus restiforme. 2. The pons Varolii. 5. The facial nerve. 6. The ori- gin of the glosso-pharyngeal nerve. 7. The ganglion of Andersch. 8. The trunk of the nerve. 9. The spinal accessory nerve. 10. The ganglion of the pneumogastric nerve. 11. Its plexiform ganglion. 12. Its trunk. 13. Its pharyn- geal branch forming the pee eal plexus (14), assisted by a fresicls from the glosso-pharyn- al (8), and one from the superior ryngeal nerve (15). 16. Cardiac branches. 17. Recurrent laryn- geal branch. 18 Anterior pulmo- nary branches. 19. Posterior pul- monary branches. 20. Csopha- geal plexus. 21. Gastric branches. 22. Origin of the spinal accessory nerve. 23. Its branches distri- buted to the sterno-mastoid mus- cle. 24. Its branches to the tra- pezius muscle. + Guy’s Hospital Reports, vol. ii. 45] 452 SPINAL ACCESSORY NERVE. nerve and in its distribution, of its sensitive function. The recurrent, or inferior laryngeal nerve, is the proper motor nerve of the larynx, and is distributed to its muscles. The Cardiac branches, two or three in number, arise from the pneu- mogastric in the lower part of the neck, and cross the lower part of the common carotid, to communicate with the cardiac branches of the sym- pathetic, and with the great cardiac plexus. The Recurrent laryngeal, or inferior laryngeal nerve, curves around the subclavian artery on the right, and the arch of the aorta on the left side. It ascends in the groove between the trachea and cesopha- gus, and piercing the lower fibres of the inferior constrictor muscle enters the larynx close to the articulation of the inferior cornu of the thyroid with the cricoid cartilage. It is distributed to all the muscles of the larynx, with the exception of the crico-thyroid, and communi- cates on the arytenoideus muscle with the superior laryngeal nerve. As it curves around the subclavian artery and aorta it gives branches to the heart and root of the lungs; and as it ascends the neck it dis- tributes filaments to the cesophagus and trachea, and communicates with the external laryngeal nerve and sympathetic. The Anterior pulmonary branches are distributed upon the anterior aspect of the root of the lungs, forming, with branches from the great cardiac plexus, the anterior pulmonary plexus. The Posterior pulmonary branches, more numerous than the ante- rior, are distributed upon the posterior aspect of the root of the lungs, and are joined by branches from the great cardiac plexus, forming the posterior pulmonary plexus. Upon the cesophagus the two nerves divide into numerous branches which communicate with each other and constitute the @sophageal plexus which completely surrounds the cylinder of the cesophagus, and accompanies it to the cardiac orifice of the stomach. The Gastric branches are the terminal filaments of the two pneumo- gastric nerves; they are spread out upon the anterior and posterior surfaces of the stomach, and are likewise distributed to the omentum, spleen, pancreas, liver, and gall-bladder, and communicate, particularly the right nerve, with the solar plexus. SPINAL ACCESSORY NERVE.—The spinal accessory nerve arises by several filaments from the side of the spinal cord as low down as the fourth or fifth cervical nerve, and ascends behind the ligamentum den- ticulatum, and between the anterior and posterior roots of the spinal nerves, to the foramen lacerum posterius. It communicates in its course with the posterior root of the first cervical nerve, and entering the foramen lacerum becomes applied against the posterior aspect of the ganglion jugulare of the pneumogastric, being contained in the same sheath of dura mater. In the jugular fossa it divides into two branches ; the smaller joins the pneumogastric immediately below the jugular ganglion, and contributes to the formation of the pharyngeal nerve ; the larger or true continuation of the nerve passes backwards SPINAL ACCESSORY NERVE. 453 Fig. 148.* behind the internal jugular vein, and descends obliquely to the upper part of the sterno-mastoid muscle. It pierces the sterno-mastoid, and * The anatomy of the side of the neck, shewing the nerves of the tongue. 1, A fragment of the temporal bone containing the meatus auditorius externus, mastoid, and styloid process. 2. The stylo-hyoid muscle. 3. The stylo- glossus. 4. The stylo-pharyngeus. 5. The tongue. 6. The hyo-glossus mus- cle; its two portions. 7. The genio-hyo-glossus muscle. 8, The genio-hvoi- deus ; they both arise from the inner surface of the symphysis of the lower jaw. 9. The sterno-hyoid muscle. 10. The sterno-thyroid. 11. The thyro-hyoid, upon which the thyro-hyoidean branch of the hypoglossal nerve is seen ramifying. 12. The omo-hyoid crossing the common caroti (13), and internal ju- gular vein (14). 15. The external carotid giving off its branches. 16, The in- ternal carotid. 17. The gustatory nerve giving off a branch to the submaxil- lary ganglion (18), and communicating a little further on with the hypoglossal nerve. 19. The submaxillary, or Wharton’s duct, passing forwards to the sublingual gland. 20. The glosso-pharyngeal nerve, passing in behind the hyo-glossus muscle. 21. The hypoglossal nerve curving around the occipital artery. 22. The descendens noni nerve, forming a loop with (23) the commu- nicans noni, which is seen to be arising by filaments oon the upper cervical nerves. 24, The pneumogastric nerve, emerging from between the internal jugular vein and common carotid artery, and entering the chest. 25. The facial nerve, emerging from the stylo-mastoid foramen, and crossing the exter- nal carotid artery. 454 HYPOGLOSSAL NERVE, then passes obliquely across the neck, communicating with the second, third, and fourth cervical nerves, and is distributed to the trapezius. The spinal accessory sends numerous twigs to the sterno-mastoid in its passage thrdugh that muscle, and in the trapezius the nervous filaments may be traced downwards to its lower border. The pneumogastric and spinal accessory nerves together (nervus vagus cum accessorio) resemble a spinal nerve, of which the former with its ganglion is the posterior and sensitive root, the latter the an- terior and motor root. Nintu pair.* HypoGLossaL NERVE (lingual). The hypoglos- sal nerve arises from the groove between the corpus pyramidale and corpus olivare by ten or fifteen filaments, which being collected into two bundles, escape from the cranium through the anterior condyloid foramen. The nerve then passes forwards between the internal carotid artery and internal jugular vein, and descends along the anterior and inner side of the vein to a point parallel with the angle of the lower jaw. It next curves inwards around the occipital artery, with which it forms a loop, and crossing the lower part of the hyo- glossus muscle to the genio-hyo-glossus, sends filaments onwards with the anterior fibres of that muscle as far as the tip of the tongue. It is distributed to the muscles of the tongue, and principally to the genio-hyo-glossus. While resting on the hyo-glossus muscle it is flattened, and beneath the mylo-hyoideus it communicates with the gustatory nerve. At its origin the hypoglossal nerve sometimes communicates with the posterior root of the first cervical nerve. The Branches of the hypoglossal nerve are :— Communicating branches with the Pneumogastric, Spinal accessory, First and second cervical nerves, Sympathetic. Descendens noni, Thyro-hyoidean branch, Communicating filaments with the gustatory nerve. The Communications with the pneumogastric and spinal accessory take place through the medium of a plexiform interlacement of branches at the base of the skull, behind the internal jugular vein. The com- munications with the sympathetic nerve are derived from the superior cervical ganglion. The Descendens noni is a long and slender twig, which quits the hypoglossal just as that nerve is about to form its arch around the occipital artery, and descends upon the sheath of the carotid vessels. Just below the middle of the neck it forms a loop with a long branch * The twelfth pair according to the arrangement of Soemmering. SPINAL NERVES. 455 (communicans noni) from the second and third cervical nerves, From the convexity of this loop branches are sent to the sterno-hyoideus, sterno-thyroideus, and both bellies of the omo-hyoideus ; sometimes also a twig is given off to the cardiac plexus, and occasionally one to the phrenic nerve. If the descendens noni be traced to its origin it will be found to be formed by a branch from the hypoglossal, and one from the first and second cervical nerves ; occasionally it receives also a filament from the pneumogastric. The Thyro-hyoidean nerve is a small branch, distributed to the thyro-hyoideus muscle. It is given off from the trunk of the hypo- glossal near the posterior border of the hyoglossus muscle, and descends obliquely over the great cornu of the os hyoides. The Communicating filaments, with the gustatory nerve, are several small twigs, which ascend upon the hyoglossus muscle near its ante- rior border, and form a kind of plexus with filaments sent down by the gustatory nerve. SPINAL NERVES. There are thirty-one pairs of spinal nerves, each arising by two roots, an anterior or motor root, and a posterior or sensitive root. The anterior roots proceed from a narrow white line, anterior lateral sulcus, on the antero-lateral column of the spinal cord, and gradually approach towards the anterior longitudinal fissure as they descend. The posterior roots, more regular than the anterior, proceed from the posterior lateral sulcus, a narrow grey stria, formed by the internal grey substance of the cord. They are larger, and the filaments of origin more numerous than those of the anterior roots. In the inter- vertebral foramina there is a ganglion on each of the posterior roots. The first cervical nerve forms an exception to these characters ; its posterior root is smaller than the anterior ; it often joins in whole or in part with the spinal accessory nerve and sometimes with the hypo- glossal: there is frequently no ganglion upon it, and when the ganglion exists it is often situated within the dura mater, the latter being the usual position of the ganglia of the last two pairs of spinal nerves. ' After the formation of a ganglion, the two roots unite and constitute a spinal nerve, which escapes through the intervertebral foramen and divides into an anterior branch for the supply of the front aspect of the body, and a posterior branch for the posterior aspect. In the first cervical and two last sacral nerves this division takes place within the dura mater and in the upper four sacral nerves externally to that cavity, but within the sacral canal. The anterior branches, with the exception of the first two cervical nerves, are larger than the posterior ; an arrangement which is proportioned to the larger extent of surface they are required to supply. 456 CERVICAL NERVES. a The Spinal nerves are divided into— Cervical , ‘ ‘ . 8 pairs Dorsal : ‘ ; ; 12 Lumbar . . SS: Sacral superior spinous process, resting in its / course upon the iliac fascia. It there pierces the transversalis fascia and muscle, communicates with the scrotal branch of the ilio-scrotal nerve, and passes along the spermatic canal with the spermatic cord to be similarly dis- tributed. The EXTERNAL CUTANEOUS NERVE (inguino-cutaneous) proceeds from the second lumbar nerve. It pierces the posterior fibres of the psoas muscle ; and crossing the iliacus obliquely, lying upon the iliac fascia, to the anterior su- perior spinous process of the ilium, passes into the thigh beneath Poupart’s * A diagram shewing the lumbar and sacral plexuses, with the nerves of the lower extremity. 1. The five lumbar nerves; which with a branch from the last dorsal, constitute the lumbar plexus. 2. The four upper sacral nerves; which, with the last lumbar, form the sacral plex- us. 3. The two musculo-cutaneous nerves. branches of the first lumbar nerve. 4. The external cutaneous nerve. 5. The genito- crural nerve. 6. The crural or femoral nerve. 7. Its muscular branches. 8. Its cutaneous branches, middle cutaneous. 9. Its descending or saphenous branches. 10. The short saphenous nerve. 11. The long or internal saphenous. 12. The obturator u nerve. 13. The gluteal nerve; a branch of the lumbo-sacral nerve. 14. The internal 24 pudic nerve. 15.° The lesser ischiatic nerve. 16. The greater ischiatic nerve. 17. The popliteal nerve. 18. The pero- 23 neal nerve. 19. The muscular branches of Wi 120 the popliteal. 20. The posterior tibial nerve; dividing at 21, into the two plan- tar nerves. 22. The external saphenous nerve, formed by the union of the com- fe: municans poplitei and communicans pero- ee nei. 23. The anterior tibial nerve. 24. The musculo-cutaneous nerve, piercing the deep fascia, and dividing into two cutane- noe at ous branches, for the supply of the dorsum of the foot. CRURAL NERVE, 471 ligament. It then pierces the fascia lata at about two inches below the anterior superior spine of the ilium, and divides into two branches, anterior and posterior. The posterior branch crosses the tensor vaginze femoris muscle to the outer and posterior side of the thigh, and supplies the integument in that region. The anterior nerve divides into two branches which are distributed to the integument upon the outer bor- der of the thigh, and to the articulation of the knee. The GENrro-cRURAL proceeds also from the second lumbar nerve. It traverses the psoas magnus from behind forwards, and:runs down on the anterior surface of that muscle and beneath its fascia to near Poupart’s ligament, where it divides into a genital and a crural branch. The genital branch (n. spermaticus seu pudendus externus) crosses the external iliac artery to the internal abdominal ring and descends along the spermatic canal, lying behind the cord to the scrotum, where it divides into branches which supply the spermatic cord and cremaster in the male, and the round ligament and external labium in the female. At the internal abdominal ring this nerve sends off a branch which after supplying the lower border of the internal oblique and transver- salis, is distributed to the integument of the groin. The erural branch (lumbo-inguinalis), the most external of the two, descends ‘along the - outer border of the external iliac artery and, crossing tbe origin of the circumflex ilii artery, enters the sheath of the femoral vessels in front of the femoral artery. It pierces the sheath below Poupart’s ligament, and is distributed to the integument of the anterior aspect of the thigh as far as its middle. This nerve is often very small, and sometimes communicates with one of the cutaneous branches of the crural nerve. The CruRAL, or FEMORAL NERVE, is the largest of the divisions of the lumbar plexus; it is formed by the union of branches from the second, third, and fourth lumbar nerves, and, emerging from beneath the psoas muscle, passes downwards in the groove between it and the iliacus, and beneath Poupart’s ligament into the thigh, where it spreads out and divides into numerous branches. . At Poupart’s ligament it is separated from the femoral artery by the breadth of the psoas muscle, which at this point is scarcely more than half an inch in diameter, and by the iliac fascia, beneath which it lies. - Branches.—W hile situated within the: pelvis the crural nerve gives off several muscular branches to the iliacus, and one to the psoas. On emerging from beneath Poupart’s ligament the nerve becomes flattened and divides into numerous branches, which may be arranged into,— Cutaneous, Muscular, Branch to the femoral sheath, Short saphenous nerve, Long saphenous nerve. The Cutaneous nerves (middle cutaneous) two in number, proceed 472 SAPHENOUS NERVES. from the anterior part of the crural, and after perforating the sar- torius muscle to which they give filaments, pierce the fascia lata and are distributed to the integument of the middle .and lower part of the thigh and of the knee. The most eaternal of these nerves perforates the upper part of the sartorius, communicates with the crural branch of the genito-crural, divides into two branches at about the middle of the thigh, and gives off numerous filaments to the anterior and outer aspect of the limb as far as the patella. The internal nerve perforates the muscle at about its middle, pierces the fascia lata at the lower third of the thigh, descends to the inner condyle, and curves forward to the front of the knee, supplying the integument by many filaments. Besides these another cutaneous branch derived from the muscular branch to the vastus externus is found on the outer side of the lower third of the thigh. The Muscular branches are several large twigs which are distributed to the muscles of the anterior aspect of the thigh. One of these is sent to the rectus; one to the vastus externus, which gives off a cutaneous twig to the outer aspect of the thigh ; one to the crureeus, and one large and long branch to the vastus internus. From the two latter, filaments are distributed to the periosteum and knee-joint. The sartorius receives its supply of nerves from the cutaneous nerves by which it is perforated. The Branch to the femoral sheath is a small nerve which passes in- wards to the sheath of the femoral vessels at the upper part of the thigh, and divides into several filaments which surround the femoral and profunda vessels. Two of these filaments, one from the front, and the other from the posterior part of the sheath, unite to form a small nerve which escapes from the saphenous opening and passes downwards with the saphenous vein. Other filaments are distributed to the adductor muscles, and communicate with the long saphenous nerve. The Short saphenous nerve (n, cutaneus internus) inclines inwards to the sheath of the femoral vessels, and divides into a superficial and a deep branch. The superficial branch passes downwards along the inner border of the sartorius muscle to the lower third of the thigh; it then pierces the fascia lata, joins the internal saphenous vein, and accompanies that vessel to the knee-joint, where it terminates by communicating with the long saphenous nerve. The deep branch de- scends on the outer side of the sheath of the femoral vessels, and crosses the sheath at its lower part to a point opposite the termi- nation of the femoral artery, where it divides into several filaments which constitute a pleaus by their communication with other nerves. One of these filaments communicates with the descending branch of the obturator nerve, another with the long saphenous nerve, and two or three are distributed to the integument upon the internal and posterior aspect of the thigh. The Long saphenous nerve (n- cutaneus internus longus) inclines inwards to the sheath of the femoral vessels, and entering the sheath OBTURATOR NERVE. 473 accompanies the femoral artery to the aponeurotic canal formed by the adductor longus and vastus internus muscles. It then quits the artery, and, passing between the tendons of the sartorius and gracilis, descends along the inner side of the leg with the internal saphenous vein, crosses in front of the inner ankle, and is distributed to the integument on the inner side of the foot as far as the great toe. The internal saphenous nerve receives from the obturator nerve two branches of communication, one near its upper part, which passes through the angle of division of the femoral artery, and the other at the internal condyle. The branches which it gives off in its course are, a femoral cutaneous branch, at about the middle of the thigh, distributed to the integument of the inner and posterior aspect of the limb, and communicating with other cutaneous filaments from the saphenous below the knee ; a tibial cutaneous branch proceeding from the nerve a little above the internal condyle, passing between the sartorius and gracilis and descending the inner aspect of the leg to the ankle ; an articular branch of small size, proceeding from the nerve, while in the aponeurotic canal of the femoral artery and passing directly to the knee-joint to supply the synovial membrane ; an ante- rior cutaneous branch proceeding from the saphenous at the inner con- dyle, perforating the sartorius, and dividing into a number of filaments which supply the integument over the patella and around the joint, and the integument of the front and outer aspect of the leg as far as the ankle ; lastly, cutaneous filaments below the knee to supply the inner side and front of the leg and foot, and articular branches to the ankle-joint. The OsruRATOR NERVE is formed bya branch from the third, and another from the fourth lumbar nerve. It passes downwards among ~ the fibres of the psoas muscle, through the angle of bifurcation of the common iliac vessels, and along the inner border of the brim of the pelvis, to the obturator foramen, where it joins the obturator artery. Having escaped from the pelvis it gives off two small twigs to the obturator externus muscle and divides into four branches, three ante- rior, which pass in front of the adductor brevis, supplying that muscle, the pectineus, the adductor longus, and the gracilis; and a posterior branch which passes downwards hehind the adductor brevis, and ramifies in the adductor magnus. From the branch which supplies the adductor brevis, a commumni- cating filament passes outwards through the angle of bifurcation of the femoral vessels to unite with the long saphenous nerve. From the branch to the adductor longus a long cutaneous nerve proceeds, which issues from beneath the inferior border of that muscle, sends filaments of communication to the plexus of the short saphenous nerve, and descends to the inner side of the knee, where it pierces the fascia and communicates with the long saphenous nerve. It is distributed to the integument upon the inner side of the leg. From the posterior branch an articular branch is given off which pierces the adductor magnus 474... SACRAL NERVES.—SACRAL PLEXUS. muscle, accompanies the popliteal artery, and is distributed to the . synovial membrane of the knee-joint on its posterior aspect. a _ The LumBo-sacRAL NERVE. — The anterior division of the fifth — lumbar nerve, conjoined with a branch from the fourth, constitutes the — lumbo-sacral nerve which descends over the base of the sacrum into — the pelvis, and assists in forming the sacral plexus, SACRAL NERVES. There are six pairs of sacral nerves; the first escape from the ver- _ tebral canal through the first sacral foramina, and the two last between the sacrum and coccyx. The posterior sacral nerves are very small 7 and diminish in size from above downwards ; they communicate with each other immediately after their escape from the posterior sacral foramina, and divide into external and internal branches. The — external branches pierce the gluteus maximus, to which they give fila- ments, and are distributed to the integument of the posterior part of the gluteal region (n. cutanei clunium posteriores). The internal supply the integument over the sacrum and coccyx. The anterior sacral nerves diminish in size from above downwards ; the first is large and unites with the lumbo-sacral nerve ; the second, of equal size, unites with the preceding ; the third, which is scarcely one-fourth so large as the third, also joins with the preceding nerves in the formation of the sacral plexus. . The fourth anterior sacral nerve is about one-third the size of the preceding sacral nerve, it divides into several branches, one of which is sent to the sacral plexus, a second to join the fifth sacral nerve, a third to the viscera of the pelvis commu- nicating with the hypogastric plexus, and a fourth to the coccygeus muscle, and to the integument around the anus. The fifth anterior sacral nerve presents about half the size of the fourth ; it divides into two branches, one of which communicates with the fourth, the other with the sixth. The siath sacral nerve (coccygeal) is exceedingly small ; it gives off an ascending filament which is continuous with the communicating branch of the fifth ; and a descending filament which passes downwards by the side of the coccyx and traverses the fibres of the great sacro-ischiatic ligament to be distributed to the gluteus maximus and to the integument. All the anterior sacral nerves re- ceive branches from the sacral ganglia of the sympathetic at their emergence from the sacral foramina. SACRAL PLEXUS. The Sacral plexus is formed by the lumbo-sacral, and by the ante- rior branches of the four upper sacral nerves. The plexus is trian- gular in form, the base corresponding with the whole length of the sacrum, and the apex with the lower part of the great ischiatic fora- GLUTEAL NERVE. - 495 men. It is in relation behind with the pyriformis muscle, and in front with the pelvic fascia, which latter separates it from the branches of the internal iliac artery, and from the viscera of the pelvis. The Branches of the sacral plexus are divisible into the internal and the eaternal; they may be thus arranged :— Internal. External. Visceral, Muscular, Muscular. Gluteal, Internal pudic, Lesser ischiatic, Greater ischiatic. The Visceral nerves are three or four large branches which are de- rived from the fourth and fifth sacral nerves: they ascend upon the side of the rectum and bladder; in the female upon the side of the rectum, the vagina and the bladder ; and interlace with the branches of the hypogastric plexus, sending in their course numerous filaments to those viscera. The Muscular branches given off within the pelvis are one or two twigs to the levator ani; an obturator branch; which curves around the spine of the ischium to reach the internal surface of the obturator internus muscle; a coccygeal branch; and an hemorrhoidal nerve which passes through the two ischiatic openings and descends to the termination of the rectum to supply the sphincter and the integu- ment. The Muscular branches supplied by the sacral plexus externally to the pelvis are, a branch to the pyramidalis; a branch to the gemellus superior; and a branch of moderate size which descends between the gemelli muscles and the ischium, and is distributed to the gemellus inferior, the quadratus femoris, and the capsule of the hip-joint. The GLUTEAL NERVE (superior gluteal) is a branch of the lumbo- sacral ; it passes out of the pelvis with the gluteal artery, through the great sacro-ischiatic foramen, and divides into a superior and an infe- rior branch. The superior branch follows the direction of the superior curved line of the ilium, accompanying the deep superior branch of the gluteal artery, and sending filaments to the gluteus medius and minimus. The inferior passes obliquely downwards and forwards between the gluteus medius and minimus, distributing numerous fila- ments to both, and terminates in the tensor vaginz femoris muscle. The INTERNAL PUDIC NERVE arises from the lower part of the sacral plexus, passes out of the pelvis through the great sacro-ischiatic foramen below the pyriformis muscle, and takes the course of the internal pudic artery. While situated beneath the obturator fascia it cat that vessel and divides into a superior and an inferior branch. 476 GREAT ISCHIATIC NERVE. The Superior nerve (dorsalis penis) ascends upon the posterior ¥ . surface of the ramus of the ischium, pierces the deep perineal fascia ‘and accompanies the arteria dorsalis penis to the glans, to which itis distributed. At the root of the penis this nerve gives off a cutaneous branch which runs along the side of the organ, gives filaments to the corpus cavernosum, and with its fellow of the opposite side supplies the integument of the upper two-thirds of the penis and prepuce. The Inferior or perineal nerve pursues the course of the internal pudic artery in the perineum and sends off three principal branches, an external perineal branch, which ascends upon the outer side of the crus penis, and supplies the scrotum ; a superficial perineal branch, which accompanies the artery of that name and distributes filaments to the scrotum, to the integument of the under part of the penis and to the prepuce ; and, thirdly, the bulbo-urethral branch, which sends twigs to the sphincter ani, transversus perinei, and accelerator urine, and terminates by ramifying in the corpus spongiosum. In the female the internal pudic nerve is distributed to the parts analogous to those of the male. The superior branch supplies the clitoris ; and the inferior the vulva and parts in the perineum. The LessER ISCHIATIC NERVE passes out of the pelvis through the great sacro-ischiatic foramen below the pyriformis muscle, and divides into muscular and cutaneous branches. The muscular branches, énfe- rior gluteal, are distributed to the gluteus maximus ; some ascending in the substance of that muscle to its upper border, and others de- scending. The cutaneous branches are, several ascending filaments to the integument over the gluteus maximus (n. cutanei clunium inferio- res), perineal cutaneous, and middle posterior cutaneous. The Perineal cutaneous nerve (pudendalis longus inferior), curves around the tuberosity of the ischium and ascends in a direction parallel to the ramus of the ischium and os pubis to the scrotum, where it communicates with the superficial perineal nerve, and divides into an internal and an external branch. The internal branch passes down upon the inner side of the testis to the scrotum ; the external branch to its outer side, and both terminate in the integument of the under border of the penis. The Middle posterior cutaneous nerve crosses the tuberosity of the ischium and pierces the deep fascia at the lower border of the gluteus maximus. It then passes downwards along the middle of the poste- rior aspect of the thigh and of the popliteal region, and is distributed to the integument as far as the middle of the calf of the leg. In its course the nerve gives off several cutaneous branches to the integument of the inner and outer side of the thigh, and in the popliteal region a communicating branch which pierces the fascia of the leg and unites with the external saphenous nerve. The Great IscHIATIC NERVE is the largest nervous cord in the body ; it is formed by the sacral plexus, or rather is a prolongation of POPLITEAL NERVE. 477 the plexus, and at its exit from the great sacro-ischiatic foramen be- neath the pyriformis muscle measures three quarters of an inch in breadth. It descends through the middle of the space between the trochanter major and tuberosity of the ischium, and along the posterior part of the thigh to about its lower third, where it divides into two large terminal branches, popliteal and peroneal. This division some- times takes place at the plexus, and the two nerves descend together side by side ; occasionally they are separated at their commencement by a part or the whole of the pyriformis muscle. The nerve in its course down the thigh rests upon the gemellus superior, tendon of the obturator internus, gemellus inferior, quadratus femoris, and adductor magnus muscle, and is covered in by the gluteus maximus, biceps, semitendinosus, and The Branches of the great ischiatic nerve, previously to its division, are muscular and articular. The muscular branches are given off from the upper part of the nerve and supply both heads of the biceps, the semi-tendinosus, semi-membranosus, and adductor magnus. The ar- ticular branch descends to the upper part of the external condyle of the femur, and divides into filaments which are distributed to the fibrous capsule and to the synovial membrane of the knee-joint. The PopLirEAL NERVE passes through the middle of the popliteal space, from the division of the great ischiatic nerve to the lower border of the popliteus muscle, accompanies the artery beneath the arch of the soleus, and becomes the posterior tibial nerve. It is superficial in the whole of its course, and lies externally to the vein and artery. The Branches of the popliteal nerve are muscular or sural, and ar- ticular, and a cutaneous branch the communicans poplitei. The Muscular branches, of considerable size, and four or five in number, are distributed to the two heads of the gastrocnemius, to the soleus, plantaris, and popliteus. The Articular nerve pierces the ligamentum posticum Winslowii, and supplies the interior of the knee-joint. It usually sends a twig to the popliteus muscle. The Communicans poplitei (communicans tibialis) is a large nerve which arises from the popliteal at about the middle of its course, and descends between the two heads of the gastrocnemius, and along the groove formed by the two bellies of that muscle ; at a variable distance below the articulation of the knee it receives a large branch, the com- municans peronei, from the peroneal nerve, and the two together con- stitute the external saphenous nerve. The External saphenous nerve pierces the deep fascia below the fleshy part of the gastrocnemius muscle, and continues its course down the leg, lying along the outer border of the tendo Achillis and by the side of the external saphenous vein which it accompanies to the foot. At the lower part of the leg it winds around the outer malleolus, and is distributed to the outer side of the foot and little toe, communicating with the external peroneal cutaneous nerye, 478 POSTERIOR TIBIAL NERVE. and ‘sending numerous filaments to the integument of the heel and _ sole of the foot. The POSTERIOR TIBIAL NERVE is continued along the posterior — aspect of the leg from the lower border of the popliteus muscle to the posterior part of the inner ankle, where it divides into the internal and external plantar nerve. In the upper part of its course it lies to the outer side of the posterior tibial artery; it then becomes placed superficially to that vessel, and at the ankle is again situated to its outer side ; in the lower third of the leg it lies parallel with the inner border of the tendo Achillis. The Branches of the posterior tibial nerve are three or four muscular twigs to the deep muscles of the posterior aspect of the leg, the branch to the flexor longus pollicis accompanies the fibular artery ; one or two filaments which entwine around the artery and then ter- minate in the integument;* and two or three plantar cutaneous branches which pass downwards upon the inner side of the os calcis and are distributed to the integument of the heel. The INTERNAL PLANTAR NERVE, larger than the external, crosses the posterior tibial vessels to enter the sole of the foot, where it lies in the interspace between the abductor pollicis and flexor brevis digi- torum ; it then enters the sheath of the latter muscle, and divides op- posite the bases of the metatarsal bones into three digital branches ; one to supply the adjoining sides of the great and second toe; the se- cond the adjoining sides of the second and third toe; and the third the corresponding sides of the third and fourth toes. This distribution is precisely similar to that of the digital branches of the median nerve. In its course the internal plantar nerve gives off cutaneous branches to the integument of the inner side and sole of the foot; muscular branches to the muscles forming the inner and middle group of the sole ; a digital branch to the inner border of the great toe; and arti- cular branches to the articulations of the tarsal and metatarsal bones. The ExTERNAL PLANTAR NERVE, the smaller of the two, follows the course of the external plantar artery to the outer border of the musculus accessorius, beneath which it sends several large muscular branches to supply the adductor pollicis and the articulations of the tarsal and metatarsal bones. It then gives branches to the integu- ment of the outer border and sole of the foot, and sends forward two digital branches to supply the little toe and one half the next. * It is extremely interesting in a physiological point of view, to observe the mode of distribution of these filaments. I have traced them in relation with several, and I have no doubt that they exist in connection with all the superfi- cial arteries. They seem to be the direct monitors to the artery of the presence or approach of danger, PERONEAL NERVE. 479 The PERONEAL NERVE is one half smaller than the popliteal ; it passes downwards by the side of the tendon of the biceps, crossing the inner head of the gastrocnemius and the origin of the soleus, to the neck of the fibula, where it.pierces the origin of the peroneus longus muscle, and divides into two branches, the anterior tibial and mus- culo-cutaneous. The Branches of the peroneal nerve previously to its division are, the communicans peronei, cutaneous, articular and muscular. The communicans peronet, much smaller than the communicans poplitei, crosses the external head of the gastrocnemius to the middle of the leg. It there sends a large branch to join the communicans poplitei and con- stitute the external saphenous nerve, and descends very much reduced in size with the external saphenous vein to the side of the external ankle, to which and to the integument of the heel it distributes fila- ments. The cutaneous branch passes down the outer side of the leg, supplying the integument. The articular is a small branch distributed to the knee-joint. The muscular branches are twigs to the short head of the biceps, peroneus longus and tibialis anticus. The ANTERIOR TIBIAL NERVE commences at the bifurcation of the peroneal, upon the head of the fibula, and passes beneath the upper _ _ part of the extensor longus digitorum, to reach the outer side of the anterior tibial artery, just as that vessel has emerged through the opening in the interosseous membrane. It descends the anterior aspect of the leg with the artery ; lying at first to its outer side, and then in front of it, and near the ankle becomes again placed to its outer side, Reaching the ankle it passes beneath the annular liga- ment; accompanies the dorsalis pedis artery, supplies the adjoining sides of the great and second toes, and communicates with the internal roneal cutaneous nerve. The Branches given off by the anterior tibial nerve are, muscular to the muscles in its course, and on the foot a éarsal branch which passes beneath the extensor brevis digitorum, and distributes filaments to the interossei muscles and to the articulations of the tarsus and metatarsus. The Muscuto-cuTANEOus nerve passes downwards in the direction of the fibula, in the substance of the peroneus longus; it then passes forwards to get between the peroneus longus and brevis, and at the lower third of the leg pierces the deep fascia, and divides into two peroneal cutaneous branches. In its course it gives off several branches to the peronei muscles. The Peroneal cutaneous nerves pass in front of the ankle-joint, and are distributed to the integument of the foot and toes; the external supplying three toes and a half, and the internal one and a half. They communicate with the saphenous and anterior tibial nerves. The external saphenous nerve frequently supplies the fifth toe and the ad- joining side of the fourth. ce st? ays hs $e A peed $s Ant fF 480 SYMPATHETIC NERVES. THE Sympathetic system consists of a series of ganglia, extending along each side of the vertebral column from the head to the coceyx, communicating with all the other nerves of the body, and distributing branches to all the internal organs and viscera. It communicates with the other nerves immediately at their exit from the cranium and vertebral canal. The fourth and sixth nerves, — however, form an exception to this rule; for with these it unites in the cavernous sinus; and with the olfactory, optic, and auditory, at their ultimate expansions. The branches of distribution accompany the arteries which supply — the different organs, and form communications around them, which are called pleauses, and take the name of the artery with which they are associated: thus we have the mesenteric plexus, hepatic plexus, splenic plexus, &c. All the internal organs of the head, neck, and — trunk are supplied with branches from the sympathetic, and some of — them exclusively ; hence it is considered a nerve of organic life. It is called the ganglionic nerve from the circumstance of being formed by a number of ganglia; and from the constant disposition which it evinces in its distribution, to communicate and form small knots or ganglia. There are five sympathetic ganglia in the head ; viz., the ganglion of Ribes ; the ciliary or lenticular; the spheno-palatine, or Meckel’s ; the otic, or Arnold’s,; and the submaxillary : three in the neck ; superior, » middle, and inferior: twelve in the dorsal region ; four in the lumbar »-region ; and four or five in the sacral region. Each ganglion may be considered as a distinct centre giving off branches in four different directions, viz., superior or ascending to communicate with the ganglion above; inferior or descending, to com- — municate with the ganglion below ; eaternal to communicate with the spinal nerves; and internal, to communicate with the sympathetic filaments of the opposite side, and to be distributed to the viscera. CRANIAL GANGLIA. Ganglion of Ribes, Ciliary, or lenticular ganglion, Spheno-palatine, or Meckel’s ganglion, Otic, or Arnold’s ganglion, Submaxillary ganglion. The GanGiion or Ripzs is a small ganglion situated upon the anterior communicating artery, and formed by the union of the sympa- thetic filaments, which accompany the ramifications of the two anterior cerebral arteries. These filaments are derived from the carotid plexus, tees et tee at ye side; and ae their intervention, the ganglion of Ribes is ay ite a oe CRANIAL GANGLIA OF THE SYMPATHETIC. ' 481 brought into connection with the carotid plexus, and with the other ganglia of the sympathetic. This ganglion, though of very small size, is interesting, as being the superior point of union between the sympa- thetic chains of opposite sides of the body. The Cin1aRy GANGLION (lenticular) is a small quadrangular and Fig. 151.* — NW =8 at I. » 18 21 * The cranial ganglia of the sympathetic nerve. 1. The ganglion of Ribes. 2. The filament by which it communicates with the carotid plexus (3). 4. The ciliary or lenticular ganglion, giving off ciliary branches for the supply of the globe of the eye. 5. Part of the inferior division of the third nerve, receiving a short thick branch (the short root) from the glion. 6. Part of the nasal nerve, receiving a longer branch (the long root) from the ganglion. 7. A slen- der filament (the sympathetic root) sent directly backwards from the ganglion to the carotid plexus. 8. Part of the sixth nerve in the cavernous sinus, receiv- ing two branches from the carotid plexus. 9. Meckel’s ganglion (spheno-pala- tine). 10. Its ascending branches, communicating with the superior maxillary nerve. 11. Its descending or palatine branches. 12. Its internal branches, spheno-palatine or nasal, 13. The naso-palatine branch, one of the nasal branches. * The naso-palatine ganglion. 14. The posterior branch of the ganglion, the Vidian nerve. 15. Its carotid branch (n. petrosus profundus) communicating with the carotid plexus. 16. Its petrosal branch (n. petrosus superficialis minor), joining the intumescentia gangliformis of the facial nerve. -17. The facial nerve. 18. The chorda tympani nerve, which descends to join the gustatory nerve. 19. The gustatory nerve. 20. The submaxillary gan- glion, receiving the chorda tympani, and other filaments from the gustatory. 21. The superior cervical ganglion of the sympathetic. 21 / 482 SPHENO-PALATINE GANGLION. flattened ganglion situated within the orbit, between the optic nerve and the external rectus muscle; it is in close contact with the optic nerve, and is surrounded by adipose tissue, which renders its dissection somewhat difficult. Its branches of distribution are the ciliary, which arise from its an- terior angles by two groups: the upper group, consisting of about four filaments ; and the lower, of five or six. They accompany the ciliary arteries in a waving course, and divide into a number of filaments which pierce the sclerotic around the optic nerve, and supply the tu- nics of the eye-ball. A small filament is said by Tiedemann, toac- company the arteria centralis retin into the centre of the globe of the. eye. Its branches of communication are three, one, the long root, which proceeds from the posterior superior angle to the zasal branch of the ophthalmic nerve ; a short thick branch, the short root, from the poste- rior inferior angle to the inferior division of the third nerve; and a slender filament, the sympathetic root, which passes backwards to the cavernous sinus, and communicates with the carotid plexus. Occa- sionally the ciliary ganglion receives also a filament of communication (middle root) from the spheno-palatine ganglion; and it sometimes sends a twig to the abducens nerve. The SPHENO-PALATINE GANGLION (Meckel’s) the largest of the cranial ganglia of the sympathetic, is very variable in its dimensions. It is situated in the spheno-maxillary fossa. Its branches are divisible into four groups; ascending, descending, internal, and posterior. The branches of distribution are the internal and the descending. The internal branches are the nasal and the naso-palatine. The zasal or spheno-palatine. nerves, four or five in number, enter the nasal fossa through the spheno-palatine foramen, and are distributed to the mucous membrane of the superior meatus, and superior and middle spongy bones. Besides these, several branches issue through small openings in the palate and sphenoid bone and supply the mucous membrane of the upper part of the pharynx and the Eustachian tube. The naso-palatine nerve (Scarpa) enters the nasal fossa with the nasal nerves, and crosses the roof of the nares to reach the septum, to which it gives several filaments. It then curves downwards and forwards to the naso-palatine canal, and enters the anterior palatine canal, where it joins with its fellow of the opposite side and receives filaments from the anterior dental and palatine nerves. By this junction an enlarge- ment is formed, the naso-palatine ganglion (Cloquet’s), which distri- butes filaments to the mucous membrane of the palate, immediately behind the incisor teeth. The descending branches are the three palatine nerves, anterior, middle, and posterior. ; The anterior palatine nerve, the largest of the three, descends from the ganglion through the posterior palatine canal, and emerges at the OTIC GANGLION. 483 posterior palatine foramen. It then passes forwards in the substance of the hard palate to which it is distributed, and communicates with the naso-palatine ganglion and with its branches. While in the pos- terior palatine canal this nerve gives off several branches which enter the nose through openings in the palate bone, and are distributed to the middle and inferior meatus, the inferior spongy bone, and the antrum. The middle palatine nerve descends through the same canal to the posterior palatine foramen, and distributes branches to the tonsil, soft palate, and uvula. The posterior palatine nerve, the smallest of the three, quits the other nerves to enter a distinct canal, from which it emerges by a se- parate opening behind the posterior palatine foramen. It is distributed to the hard palate and gums near the point of its emergence, and to the tonsil and soft palate. The branches of communication are the ascending and the posterior. The ascending branches are, one or two to join the superior maxillary nerve ; one to the abducens nerve ; one to the ciliary ganglion con- stituting its middle root ; and occasionally two filaments to the optic nerve within the orbit. The posterior branch is the Vidian or ptery- goid nerve. ee i The Vidian* nerve passes directly backwards from the spheno- palatine ganglion, radi rn the pterygoid or Vidian canal, to the fora- Pe Ah men lacerum basis cranii, where it divides into two branches, the 3 carotid and petrosal. The carotid branch (n. petrosus profundus) Zit crosses the foramen lacerum, surrounded by the ligamentous substance fic’ : which closes that opening and enters the carotid canal by several filaments to join the carotid plexus. The petrosal branch (n. petrosusy Z,.. superficialis major) enters the cranium through the foramen lacerum wee basis cranii, piercing the ligamentous substance of the latter, and passes backwards beneath the Casserian ganglion and dura mater, embedded in a groove upon the anterior surface of the petrous bone, to the hiatus Fallopii. In the hiatus Fallopii the petrosal branch of the Vidian receives a twig from Jacobson’s nerve and terminates in the intumescentia gangliformis of the facial nerve. While in the pterygoid canal the Vidian nerve sends off a minute branch which passes through an opening in the sphenoid bone and joins the otic ganglion. The Oric GancLion (Arnold’s)+ is a small oval-shaped and flat- Ar tened ganglion, resting against the inner surface of the inferior2..” 4. maxillary nerve, immediately below the foramen ovale ; it is in relax, Kth | tion externally with the trunk of the inferior maxillary nerve, just at 2. * od * Guido Guidi, latinised into Vidus Vidius, was professor of anatomy we ya medicine in the College of France in 1542. His work is posthumous, and wae 2 aan published in 1611. one 3 + Frederick Arnold, ‘* Dissertatio Inauguralis de Parte Cephalica Ne Leaers Sympathetici.’? Heidelberg, 1826; and ‘‘ Ueber den Ohrknoten,’’ 1828. a Ler AR Pre Bo POOF EO «. ‘ Va ee re all aaa 484 SUBMAXILLARY GANGLION. the point of union of the motor root ; internaily it rests against the cartilage of the Eustachian tube and tensor palati muscle ; and poste- riorly it is in contact with the arteria meningea media. It is closely adherent to the internal pterygoid nerve, and appears like a swelling upon that branch. The branches of the otic ganglion are seven in number ; two of distribution, and five of communication. The branches of distribution are, a small filament to the tensor tympani muscle, and one to the tensor palati muscle ; the latter is usually derived from the internal pterygoid nerve, at the point where that nerve is enclosed by the ganglion. The branches of communication are, two or three filaments to the outer portion of the inferior maxillary nerve ; one or two filaments to the auricular nerve; a filament to the chorda tympani ; filaments to the arteria meningea media to communicate with the nervi molles ; a filament which enters the cranium through the foramen spinosum with the arteria meningea media and accompanies the nervus petrosus superficialis minor to the hiatus Fallopii, where it joins the intume- scentia gangliformis of the facial nerve ; a filament which enters the cranium through a small canal behind the foramen rotundum to join the Casserian ganglion ; a filament which enters a small canal near the foramen ovale to communicate with the Vidian nerve; and the nervus petrosus superficialis minor. The latter nerve ascends from the ganglion to a small canal situated between the foramen ovale and foramen spinosum, and passes backwards on the petrous bone to the hiatus Fallopii, where it divides into two filaments. One of these filaments enters the hiatus and joins the intumescentia gangliformis of the facial ; the other passes to a minute foramen nearer the base of the petrous bone and enters the tympanum, where it communicates with a branch of Jacobson’s nerve. The SuBMAXILLARY GANGLION is a small round or triangular ganglion, situated upon the submaxillary gland, in close relation with the gustatory nerve and near the posterior border of the mylo-hyoi- deus muscle. Its branches of distribution, six or eight in number, divide into many filaments, which supply the substance of the submaxillary gland and Wharton’s duct. Its branches of communication are, two or three from and to the gustatory nerve ; one from the chorda tympani ; and one or two fila- ments which pass to the facial artery and communicate with the nervi molles from the cervical portion of the sympathetic. CAROTID PLEXUS.—The ascending branch of the superior cervical ganglion enters the carotid canal with the internal carotid artery, and divides into two branches, which form several loops of communication with each other around the artery. These branches, together with those derived from the petrosal branch of the Vidian, constitute the CERVICAL GANGLIA. 485 carotid plexus. They also form frequently a small gangliform swelling upon the under part of the artery, which is called the carotid ganglion. The latter, however, is not constant. The continuation of the carotid plexus onwards with the artery by the side of the sella turcica, is called the cavernous The carotid plexus is the centre of communication between all the cranial ganglia ; and being derived from the superior cervical ganglion, between the cranial ganglia and those of the trunk, it also com-. municates with the greater part of the cerebral nerves, and distributes filaments with each of the branches of the internal carotid, which accompany those branches in all their ramifications. Thus, the Ganglion of Ribes is formed by the union of the filaments which accompany the anterior cerebral arteries, and which meet on the anterior communicating artery. The ciliary ganglion communi- cates with the plexus by means of the long branch which is sent back to join it in the cavernous sinus. The spheno-palatine, and with it the naso-palatine ganglion, joins the plexus by means of the carotid branch of the Vidian. The submasillary ganglion is brought into connection with it by means of the otic ganglion, and the otic ganglion by means of the tympanic nerve and the Vidian. It communicates with the third nerve in the cavernous sinus, and through the ciliary ganglion ; frequently with the fourth in the formation of the nerve of the tentorium ; with the Casserian ganglion ; with the ophthalmic division of the fifth i in the cavernous sinus, and by means of the ciliary ganglion ; with the superior maxillary, through the spheno-palatine ganglion ; and with the inferior maxillary, through the otic ganglion. It sends two branches directly to the sixth nerve, which unite* with it as it crosses the cavernous sinus ; it communi- cates with the facial and auditory nerves, through the medium of the petrosal branch of the Vidian ; and with the glosso-pharyngeal by means of two filaments to the tympanic nerve. CERVICAL GANGLIA. The Superior cervical ganglion is long and fusiform, of a greyish colour, smooth, and of considerable thickness, extending from within an inch of the carotid foramen in the petrous bone to opposite the lower border of the third cervical vertebra. It is in relation in front with the sheath of the internal carotid artery and internal jugular vein ; and behind with the rectus anticus major muscle. Its branches, like those of all the sympathetic ganglia in the trunk, are divisible into superior, inferior, external, and internal; to which may be added, as proper to this ganglion, anterior. The superior (carotid nerve) is a single branch which ascends by * Panizza, in his “‘ Experimental Researches on the Nerves,’’ denies this communication, and states very vagiely that “they are merely lost and en- twined around it.”—Edinburgh Medical and Surgical Journal, January 1836. 486 CERVICAL GANGLIA. the side of the internal carotid, and divides into two branches ; one lying to the outer side, the other to the inner side of that vessel. The two branches enter the carotid canal, and by their communica- tions with each other and with the petrosal branch of the Vidian, constitute the carotid plexus. The inferior or descending branch, sometimes two, is the cord of communication with the middle cervical ganglion. The external branches are numerous, and may be divided into two sets: those which communicate with the glosso-pharyngeal, pneu- mogastric, and hypoglossal nerves ; and those which communicate with the three first cervical nerves. The txternal branches are three in number: pharyngeal, to assist in forming the pharyngeal plexus ; laryngeal, to join the superior laryn- geal nerve and its branches ; and the superior cardiac nerve, or nervus superficialis cordis. The anterior branches accompany the carotid artery with its branches, around which they form intricate plexuses, and here and there small ganglia ; they are called, from the softness of their texture, nervi molles, and from their reddish hue, xervi subruji. The Middle cervical ganglion (thyroid ganglion) is of small size, and sometimes altogether wanting. It is situated opposite the fifth * cervical vertebra, and rests upon the inferior thyroid artery. This relation is so constant, as to have induced Haller to name it the “ thyroid ganglion.” Its superior brunch, or branches, ascend to communicate with the superior cervical ganglion. Its inferior branches descend to join the inferior cervical ganglion ; one of these frequently passes in front of the subclavian artery, the other behind it. Its eaternal branches communicate with the third, fourth, and fifth cervical nerves. Its internal branches are, filaments which accompany the inferior thyroid artery, the inferior thyroid plexus; and the middle cardiac nerve, hervus cardiacus magnus. The Inferior cervical ganglion (vertebral ganglion) is much larger than the preceding, and is constant in its existence. It is of a semi- lunar form, and is situated upon the base of the transverse process of the seventh cervical vertebra, immediately behind the vertebral artery: hence its title to the designation “ vertebral ganglion.” i superior branches communicate with the middle cervical gan- glion. The inferior branches pass some before and some behind the sub- clavian artery, to join the first thoracic ganglion. The eaternal branches consist of two sets ; one which communicat®s with the sixth, seventh, and eighth cervical and first dorsal nerve ; and one which accompanies the vertebral artery along the vertebral ~ CARDIAC NERVES. 487 canal, forming the vertebral plexus. This plexus sends filaments to all the branches given off by the artery, and communicates in the cranium with the filaments of the carotid plexus accompanying the branches of the internal carotid artery. The internal branch is the inferior cardiac nerve, nervus cardiacus minor. CaRDIAC NERVES.*— The superior cardiac nerve (nervus super- ficialis cordis) arises from the lower part of the superior cervical ganglion ; it then descends the neck behind the common carotid artery and parallel with the trachea, crosses the inferior thyroid artery, and running by the side of the recurrent. laryngeal nerve for a short dis- tance, passes behind the arteria innominata to the concavity of the arch of the aorta, where it joins the cardiac ganglion. In its course it receives branches from the pneumogastric nerve, and sends filaments to the thyroid gland and trachea. The Middle cardiac nerve (nervus cardiacus magnus) proceeds from the middle cardiac ganglion, or, in its absence, from the cord of communication between the superior and inferior. It is the largest of the three nerves, and lies nearly parallel with the recurrent laryn- geal. At the root of the neck it divides into several branches, which pass some before and some behind the subclavian artery; it com- municates with the superior and inferior cardiac, and with the pneu- mogastric and recurrent nerves, and descends to the bifurcation of the trachea, to the great cardiac plexus. The Inferior cardiac nerve (nervus cardiacus minor) arises from the inferior cervical ganglion, communicates freely with the recurrent laryngeal and middle cardiac nerves, and descends to the front of the bifurcation trachea, to join the great cardiac plexus. The Cardiac ganglion is a ganglionic enlargement of variable size, situated beneath the arch of the aorta, to the right side of the liga- ment of the ductus arteriosus. It receives the superior cardiac nerves of opposite sides of the neck and a branch from the pneumogastric, and gives off numerous branches to the cardiac plexuses. The Great cardiac plexus is situated upon the bifurcation of the trachea, above the right pulmonary artery, and behind the arch of the aorta. It is formed by the convergence of the middle and inferior cardiac nerves, and by branches from the pneumogastric and descen- dens noni nerve, and first thoracic ganglion. The Anterior cardiac plexus is situated in front of the ascending | aorta, near its origin. It is formed by the communications of filaments that proceed from three different sources, namely, from the superior cardiac nerves, crossing the arch of the aorta ; from the cardiac ganglion beneath the arch; and from the great cardiac plexus, passing between the ascending aorta and the right auricle. The anterior cardiac plexus * There is no constancy with regard to the origin and course of these nerves ; therefore the student must not be disappointed in finding the description im discord with his dissection. 488 THORACIC GANGLIA. ‘supplies the anterior aspect of the heart, distributing numerous fila- ments with the left coronary artery, which form the anterior coronary The Posterior cardiac plexus is formed by numerous branches from the great cardiac plexus, and is situated upon the posterior part of the ascending aorta, near its origin. It divides into two sets of branches: one set accompanying the right coronary artery in the auriculo-ventri- cular sulcus; the other set joining the artery on the posterior aspect of cea heart. They both together constitute the posterior coronary The great cardiac plexus likewise gives branches to the auricles of the heart, and others to assist in forming the anterior and posterior pulmonary pleauses. THORACIC GANGLIA. The Thoracic ganglia are twelve in number on each side. They are flattened and triangular, or irregular in form, and present the peculiar grey colour and pearly lustre of the other sympathetic ganglia; they rest upon the heads of the ribs, and are covered in by the pleura costalis. The two first ganglia and the last are usually the largest. Their branches are superior, inferior, external, and internal. The superior and inferior are prolongations of the substance of the ganglia rather than branches; the former to communicate with the ganglion above, the /atter with that below. The eaternal branches, two or three in number, communicate with both roots of each of the spinal nerves. The internal branches of the five upper ganglia are pulmonary to join the pulmonary plexuses ; asophageal to the cesophageal plexus and aortic to the thoracic aorta and its branches; the first thoracic ganglion more- over sends branches to the cardiac plexuses. The branches of the lower ganglia are aortic, and several large cords which unite to form the two splanchnic nerves. The Great splanchnic nerve arises from the sixth dorsal ganglion, and receives branches from the seventh, eighth, ninth, and tenth, which augment it to a nerve of considerable size. It descends in front of the vertebral column, within the posterior mediastinum, pierces the diaphragm immediately to the outer side of each crus, and termi~ nates in the semilunar ganglion. The Lesser splanchnic nerve (renal) is formed by filaments from the tenth, eleventh, and sometimes from the twelfth dorsal ganglion. It pierces the diaphragm, and descends to join the renal plexus, The Semilunar ganglion is a large, irregular, gangliform body, pierced by numerous openings, and appearing like the aggregation of a number of smaller ganglia, having spaces between them. It is situated by the side of the celiac axis, and communicates with the ganglion of the opposite side, both above and below that trunk, so as | | LUMBAR GANGLIA. 489 to form a gangliform circle, from which branches pass off in all direc- tions, like rays from a centre. Hence the entire circle has been named the solar plexus. The Solar pleaus receives the great splanchnic nerves; part of the lesser splanchnic nerves ; the termination of the right pneumogastric nerve ; some branches from the right phrenic nerve ; and sometimes. one or two filaments from the left. It sends numerous filaments which accompany, under the name of plexuses, all the branches given off by the abdominal aorta. Thus, we have derived from the solar plexus the— Phrenic plexuses, Gastric plexus, Hepatic plexus, Splenic plexus, Supra-renal plexuses, Renal. plexuses, Superior mesenteric plexus, Spermatic plexuses, Inferior mesenteric plexus, The Renal plexus is formed chiefly by the lesser splanchnic nerve, but receives many filaments from the solar plexus. The Spermatic plexus is formed principally by the renal plexus. The Inferior mesenteric plexus receives filaments from the aortic plexus. LUMBAR GANGLIA, The Lumbar ganglia are four in number on each side, of the peculiar pearly grey colour, fusiform, and situated upon the anterior part of the bodies of the lumbar vertebre. The superior and inferior branches of the lumbar ganglia are branches of communication with the ganglion above and below, as in the dorsal region. “The external branches, two or three in number, communicate with the lumbar nerves. The internal branches consist of two sets; of which the upper pass inwards in front of the abdominal aorta, and form around that trunk a plexiform interlacement, which constitutes the lumbar aortic pleaus ; the lower branches cross the common iliac arteries, and unite over the promontory of the sacrum, to form the hypogastric plexus. — The Lumbar aortic pleaus is formed by branches from the lumbar ganglia, and receives filaments from the solar and superior mesenteric plexuses. It sends filaments to the inferior mesenteric plexus, and ter- minates in the hypogastric plexus. The Hypogastric pleaus is formed by the termination of the aortic plexus, and by the union of branches from the lower lumbar ganglia. It is situated over the promontory of the sacrum, between the two 490 SACRAL GANGLIA. common iliac arteries, and bifurcates inferiorly into two lateral por- tions, which communicate with branches from the fourth and fifth sacral nerves. It distributes branches to all the viscera of the pelvis, and sends filaments which accompany the branches of the internal iliac artery. SACRAL GANGLIA. The Sacral ganglia are four or five in number on each side. They are situated upon the sacrum, close to the anterior sacral foramina, and resemble the lumbar ganglia in form and mode of connection, although much smaller in size. The superior and inferior branches communicate with the ganglia above and below. The eaternal branches communicate with the sacral nerves. The internal branches communicate very freely with the lateral divisions of the hypogastric plexus, and are distributed to the pelvic viscera. The last pair of sacral ganglia give off branches which join a small ganglion, situated on the first bone of the coccyx, called the ganglion impar, or azygos. This ganglion resembles in its position and function the ganglion of Ribes, serving to connect the inferior ex- tremity of the sympathetic system, as does the former ganglion its upper extremity: It gives off a few small branches to the coccyx and rectum. 49] _ CHAPTER IX. ORGANS OF SENSE. THE organs of sense, the instruments by which the animal frame - is brought into relation with surrounding nature, are five in number. Four of these organs are situated within the head, viz. the apparatus of smell, sight, hearing, and taste, and the remaining organ, of touch, is resident in the skin, and distributed over the surface of the body. THE NOSE AND NASAL FOSS. The organ of smell consists essentially of two parts: one external, the nose; the other internal, the nasal fosse. The nose is the triangular pyramid projecting from the centre of the face, immediately above the upper lip. Superiorly, it is connected with the forehead, by means of a narrow bridge ; inferiorly, it presents two openings, the zostrils, which overhang the mouth, and are so constructed that the odour of all substances must be received by the nose before they can be introduced within the lips. The septum between the openings of the nostrils is called the columna. Their entrance is guarded by a number of stiff hairs (vibrisse) which project across the openings, and act as a filter in preventing the introduction of foreign substances, such as dust or insects, with the current of air intended for respiration. The anatomical elements of which the nose is composed are,—l, Integument. 2. Muscles. 3. Bones. 4. Fibro-cartilages. 5. Mucous membrane. 6. Vessels and nerves. 1. The Jntegument forming the tip (lobulus) and wings (ale) of the nose is extremely thick and dense, so as to be with difficulty separated from the fibro-cartilage. It is furnished with an abundance of seba- ceous follicles, which by their oily secretion, protect the extremity of the nose in excessive alternations of temperature. The sebaceous mat- ter of these follicles becomes of a dark colour upon the surface, from the attraction of the carbonaceous matter floating in the atmosphere ; hence the spotted appearance which the tip of the nose presents in large cities. When the integument is firmly compressed, the inspis- sated sebaceous secretion is squeezed out from the follicles, and, taking the cylindrical form of their excretory ducts, has the appearance of small white maggots with black heads, 492 STRUCTURE OF THE NOSE. 2. The Muscles are brought into: view by reflecting the integument: they are the pyramidalis nasi, compressor nasi, dilatator naris, levator labii superioris alzeque nasi, and depressor labii superioris aleeque nasi. They have been already described with the muscles of the face. 3. The Bones of the nose are the nasal, and nasal processes of the superior maxillary. 4, The Fibro-cartilages give form and stability to the outwork of the nose, providing at the same time, by their elasticity, against in- juries. They are five in number, namely, the— Fibro-cartilage of the septum, Two lateral fibro-cartilages, Two alar fibro-cartilages. The Fibro-cartilage of the septum, somewhat triangular in form, divides the nose into its two nostrils. It is connected above with the nasal bones and lateral fibro-cartilages; behind, with the ethmoidal septum and vomer; and below, with the palate processes of the superior maxillary bones. The alar fibro-cartilages and columna move freely upon the fibro-cartilage of the septum, being but loosely con- nected with it by perichondrium. The Lateral fibro-cartilages are also ; triangular: they are connected, in front, Fig.'153.° with the fibro-cartilage of the septum ; above with the nasal bones; behind with the nasal processes of the supe- rior maxillary bones; and below with the alar fibro-cartilages. Alar fibro-cartilages.—Each of these cartilages is curved in such a manner as to correspond with the opening of the nostril, to which it forms a kind of rim. The inner portion is loosely con- nected with the same part of the oppo- site cartilage, so as to form the co- lumna. It is expanded and thickened at the point of the nose to constitute the Jobe; and upon the side forms a curve- corresponding with the form of the ala. Thiscurveis prolonged down- wards and forwards in the direction of the posterior border of the ala by three or four small fibro-cartilaginous plates, which are appendages to the alar fibro-cartilage. * The fibro-cartilages of the nose. 1. One of the nasal bones. 2. The fibro- cartilage of the septum. 3. The lateral fibro-cartilage. 4. The alar fibro-car- tilage. 5. The central portions of the alar fibro-cartilages which constitute the columna, 6. The appendix of the alar fibro-cartilage. 7. The nostrils. NASAL FOSSA. 493 The whole of these fibro-cartilages are connected with each other, and to the bones, by perichondrium, which, from its membranous structure, permits of the freedom of motion existing between them. 5. The Mucous membrane, lining the interior of the nose, is contin- uous with the skin externally, and with the pituitary membrane of the nasal fosse within. Around the entrance of the nostrils it is provided with numerous vibrisse. 6. Vessels and Nerves. — The Arteries of the nose are the lateralis nasi from the facial, and the nasalis septi from the superior coronary. Its Nerves are the facial, infra-orbital, and nasal branch of the ophthalmic. NASAL FOSSZ. To obtain a good view of the nasal fosse, the face must be divided through the nose by a vertical incision, a little to one side of the middle line. The Nasal fosse are two irregular, compressed cavities, extending backwards from the nose to the pharynx. They are bounded supe- riorly by the lateral cartilage and by the nasal, sphenoid and ethmoid bones ; inferiorly by the hard palate ; and in the middle line they are separated from each other by a bony and fibro-cartilaginous septum. A plan of the boundaries of the nasal fossze will be found at age 62. : Upon the outer wall of each fossa, in the dried skull, are, three projecting processes, termed spongy bones. The two superior belong to the ethmoid, the inferior is a separate bone. In the fresh fossz these are covered with mucous membrane, and serve to increase its surface by their prominence and by their convoluted form. The space intervening between the superior and middle spongy bone is the superior meatus; the space between the middle and inferior the middle meatus; and that between the inferior and the floor of the fossa the inferior meatus. These meatuses are passages which extend from before backwards, and it is in rushing through and amongst these that the atmosphere deposits its odorant particles upon the mucous membrane. There are several openings into the nasal fosse: thus, in the swperior meatus are the openings of the sphenoidal and posterior ethmoidal cells; in the middle the anterior ethmoidal cells, the frontal sinuses, and the antrum maxillare ; and, in the inferior meatus, the termination of the nasal duct. In the dried bone there are two additional openings, the spheno-palatine and the anterior palatine foramen ; the former being situated in the superior, and the latter in the inferior meatus. The Mucous membrane of the nasal fosse is called pituitary, or Schneiderian.* The former name being derived from its secretion, * Conrad Victor Schneider, professor of Medicine at Wittenberg. His work, entitled De Catarrhis, &c. was published in 1661. 494 EYE.—SCLEROTIC COAT. the latter from Schneider, who was the first to show that the secre- tion of the nose proceeded from the mucous membrane, and not from the brain, as was formerly imagined. It is continuous with the general gastro-pulmonary mucous membrane, and may be traced — through the openings in the meatuses, into the sphenoidal and eth- moidal cells ; into the frontal sinuses ; into the antrum maxillare ; through the nasal duct to the surface of the eye, where it is con- tinuous with the conjunctiva; along the Eustachian tubes into the tympanum and mastoid cells, to which it forms the lining membrane ; and through the posterior nares into the pharynx and mouth, and thence through the lungs and alimentary canal. The surface of this membrane is furnished with a columnar epithe- lium supporting innumerable vibratile cilia. Vessels and Nerves.—The Arteries of the nasal fosse are the an- terior and posterior ethmoidal, from the ophthalmic artery ; and the spheno-palatine and pterygo-palatine from the internal maxillary. The Nerves are, the olfactory, the spheno-palatine branches from Meckel’s ganglion, and the nasal branch of the ophthalmic. The ultimate filaments of the olfactory nerve terminate in minute papilla. THE EYE, WITH ITS APPENDAGES. The form of the eyeball is that of a sphere, of about one inch in diameter, having the segment of a smaller sphere ingrafted upon its anterior surface, which increases its antero-posterior diameter. The axes of the two eyeballs are parallel with each other, but do not correspond with the axes of the orbits, which are directed outwards. The optic nerves follow the direction of the orbits, and therefore enter the eyeballs to their nasal side. The Globe of the Eye is composed of twnics and of refracting media called humours. The tunics are three in number, the 1. Sclerotic and Cornea, 2. Choroid, Iris, and Ciliary processes, 3. Retina and Zonula ciliaris. The humours are also three — Aqueous, Crystalline (lens), Vitreous. First Tunic. — The Sclerotic and Cornea form the external tunic of the eyeball, and give it its peculiar form. Four-fifths of the globe are invested by the sclerotic, the remaining fifth by the cornea. The Sclerotic (oxAngds, hard) is a dense fibrous membrane, thicker behind than in front. It is continuous, posteriorly, with the sheath of the optic nerve, which is derived from the dura mater, and is pierced by that nerve as well as by the ciliary nerves and arteries. 1 he i oh el TUNICA ALBUGINEA. 495 Anteriorly it presents a bevelled edge which receives the cornea in the same way that a watch-glass is received by the groove in its case. Its anterior surface is covered by a thin tendinous layer, the tunica albuginea, derived from the expansion of the tendons of the four recti muscles. By its posterior surface it gives attachment to the two oblique muscles. The tunica albuginea is covered, for a part of its extent, by the mucous membrane of the front of the eye, the conjunc- tiva ; and, by reason of the brilliancy of its whiteness, gives occasion to the common expression, “ the white of the eye.” At the entrance of the optic nerve the sclerotic forms a thin.~, ,,..... ertbriform lamella (lamina eribrosa), which is pierced by a number of »./ minute openings for the passage of the nervous filaments. One of ~~ these openings, larger than the rest, and situated in the centre of the lamella, is the porus opticus, through which the arteria centralis retinze ye ges enters the eyeball. evs. Se Fig. 153.* * A longitudinal section of the globe of the eye. 1 The sclerotic, thicker behind than in front. 2. The cornea, received within the anterior margin of the sclerotic, and connected with it by means of a bevelled edge. 3. The cho- roid, connected anteriorly with (4) the ciliary ligament, and (5) the ciliary pro- cesses. 6. Theiris. 7. The pupil. 8 The third layer of the eye, the retina, terminating anteriorly by an pt border at the commencement of the ciliary processes. 1. The canal of Petit, which encircles the lens (12); the thin layer in front of this canal is the zonula ciliaris, a prolongation of the vascular layer of the retina to the lens. 10. The anterior chamber of the eye, containing the aqueous humour: the lining membrane by which the humour is secreted is represented in the diagram. 11. The posterior chamber. 12. The lens, more convex behind than before, and enclosed in its proper capsule. 13. The vitreous humour enclosed in the hyaloid membrane, and in cells formed in its interior by that membrane. 14. A tubular sheath of the hyaloid membrane, which serves for the passage of the artery of the capsule of the lens. 15. The neurilemma of the optic nerve. 16. The arteria centralis retinee, embedded in the centre of the optic nerve. %, . ~ & \ f\ 496 STRUCTURE OF THE CORNEA. The Cornea (corneus, horny) is the transparent projecting layer that constitutes the anterior fifth of the globe of the eye. In its form it is circular, concavo-convex, and resembles a watch-glass. It is received by its edge, which is sharp and thin, within the bevelled border of the sclerotic, to which it is very firmly attached, and it is somewhat thicker than the anterior portion of that tunic. When examined from the exterior, its vertical diameter is seen to be about one sixteenth shorter than the transverse, in consequence of the overlapping above and below, of the margin of the sclerotica ; on the interior, however, its outline-is perfectly circular. ae The cornea is composed of four layers, namely, of the conjunctiva ; ».e +f the cornea proper, which consists of several thin lamelle connected together by an extremely fine areolar tissue ; of the cornea elastica, a“ fine, elastic, and exquisitely transparent membrane, exactly ap- * plied to the inner surface of the cornea proper ;” and of the lining , membrane of the anterior chamber of the eyeball. The cornea elastica ~ is remarkable for its perfect transparency, even when submitted for many days to the action of water or alcohol; while the cornea proper is rendered opaque by the same immersion. To expose this mem- brane, Dr. Jacob suggests that the eye should be placed in water for six or eight days, and then that all the opaque cornea should be removed layer after layer. Another character of the cornea elastica is its great elasticity, which causes it to roll up when divided or torn, in the same manner as the capsule of the lens. The use of this layer, according to Dr. Jacob, is to “ preserve the requisite permanent correct curvature of the flaccid cornea proper.” The opacity of the cornea, produced by pressure on the globe, re- sults from the infiltration of fluid into the areolar tissue connecting its layers. This appearance cannot be produced in a sound living eye. Dissection —The sclerotic and cornea are now to be dissected away from the second tunic ; this, with care, may be easily performed, the only connections subsisting between them being at the circumference of the iris, the entrance of the optic nerve, and the perforation of the ciliary nerves and arteries. Pinch up a fold of the sclerotic near its anterior circumference, and make a small opening into it, then raise the edge of the tunic, and with a pair of fine scissors, having a probe point, divide the entire circumference of the sclerotic, and cut it away bit by bit. Then separate it from its attachment around the circum- ference of the iris by a gentle pressure with the edge of the knife. The dissection of the eye must be conducted under water. In the course of this dissection the ciliary nerves and long ciliary arteries will be seen passing forwards between the sclerotic and cho- roid, to be distributed to the iris. SEconpD TuNIc.—The second tunic of the eyeball is formed by the chogoid, ciliary ligament and iris, the ciliary processes being an ap- pendage developed from its inner surface. The Choroid * is a vascular membrane of a rich chocolate-brown * The word choroid has been very much abused in anatomical language ; it Ree etree A eg de CHOROID.—CILIARY LIGAMENT. 497 colour upon its external surface, and of a deep black colour within. It is connected to the sclerotic, externally, by°an extremely fine areolar tissue, and by nerves and vessels. Internally it is in simple contact with the third tunic of the eye, the retina. It is pierced posteriorly for the passage of the optic nerve, and is connected anteri- orly with the iris, ciliary processes, and with the line of junction of the cornea and ‘sclerotic, by a dense white structure, the ciliary liga- ment, which surrounds the circumference of the iris like a ring. The choroid membrane is composed of three layers:—An -eaternal or venous layer, which consists principally of veins arranged in a pecu- liar manner: hence they have been named vene vorticose. The mark- _. ing upon the surface of the membrane produced by these veins, ~ s resembles so many centres, to which a number of curved lines converge. © It is this layer which is connected with the ciliary ligament. The middle or arterial layer (tunica Ruyschiana*) is formed principally by the ramifications of minute arteries. It is reflected inwards at its junction with the ciliary ligament, so as to form the ciliary processes. The internal layer is a delicate membrane (membrana pigmenti) com- posed of several laminz of nucleated hexagonal cells, which contain the granules of pigmentum nigrum, and are arranged so as to resemble a tesselated pavement. In animals the pigmentum nigrum, upon the posterior wall of the eyeball, is replaced by a layer of considerable extent, and of metallic brilliancy, called the tapetum. The Ciliary ligament, or circle, is the bond of union between the external and middle tunics of the eyeball, and serves to connect the cornea and sclerotic, at their line of junction, with the iris and external layer of the choroid. It is also the point to which the ciliary nerves and vessels proceed previously to their distribution, and it receives the anterior ciliary arteries through the anterior margin of the sclerotic. A minute vascular canal is situated within the ciliary ligament, called the ciliary canal, or the canal of Fontana,} from its dis- coverer. was originally applied to the membrane of the fcetus called chorion from the Greek word X0e60Y, domicilium, that membrane being, as it were, the abode or receptacle of the foctus. Xégiov comes from xweéw, to take or receive. Now it so happens that the chorion in the ovum is a vascular membrane of peculiar structure. Hence the term choroid, xoesay cides, like the chorion, has been used indiscriminately to signify vascular structures, as in the choroid membrane of the eye, the choroid plexus, &c., and we find Cruveilhier in his admirable work on Anatomy, vol. iii. p. 463, saying in a note, “‘ Choroide est synonyme de vasculeuse.’’ * Ruysch was born at the Hague in 1638, and was appointed professor of Anatomy at Amsterdam in 1665. His whole life was employed in making in- jected preparations, for which he is justly celebrated, and he died at the ad- vanced age of ninety-three years. He came to the conclusion that the hogy was entirely made up of vessels. + Felix Fontana, an anatomist of Tuscany. His ‘‘ Description of a New Canal in the Eye,’’ was published in 1778, in a Letter to the Professor of Ana- tomy in Upsal. " K a» 498 IRIS.—CILIARY PROCESSES. The Jris (iris, a rainbow,) is so named from its variety of colour in different individuals: it forms a septum between the anterior and posterior chambers of the eye, and is pierced somewhat to the nasal side of its centre by a circular opening, which is called the pupil. By its periphery it is connected with the ciliary ligament, and by its inner circumference forms the margin of the pupil; its anterior surface looks towards the cornea, and the posterior towards the ciliary pro- cesses and lens. The iris is composed of two layers, an anterior or muscular, consist- ing of radiating fibres which converge from the circumference towards the centre, and have the power of dilating the pupil; and circular, which surround the pupil like a sphincter, and by their action produce contraction of its area. The posterior layer is of a deep purple tint, and is thence named wvea, from its resemblance in colour to a ripe grape. The Ciliary processes may be seen in two ways, either by removing the iris from its attachment to the ciliary ligament, when a front view of the processes will be obtained, or by making a transverse section through the globe of the eye, when they may be examined from behind, as in fig. 154. Fig. 154.* The ciliary processes consist of a number of triangular folds, formed apparently by the plaiting of the middle and internal layer of the choroid. According to Zinn, they are about sixty in number, and * The anterior segment of a transverse section of the globe of the eye, seen from within. 1. The divided edge of the three tunics; sclerotic, choroid (the dark layer), and retina. 2. The pupil. 3. The iris, the surface presented to view in this section being the uvea. 4. The ciliary processes. 5. The scallop- ed anterior border of the retina. —_—Ser ee RETINA.—STRUCTURE. 499 may be divided into large and small, the latter being situated in the spaces between the former. Their periphery is connected with the ciliary ligament, and is continuous with the middle and internal layer of the choroid. The central border is free, and rests against the cir- cumference of the lens. The anterior surface corresponds with the uvea; the posterior receives the folds of the zonula ciliaris between its processes, and thus establishes a connection between the choroid and the third tunic of the eye. The ciliary processes are covered with a thick layer of pigmentum nigrum, which is more abundant upon them, and upon the anterior part of the choroid, than upon the pos- terior. When the pigment is washed off, the processes are of a whitish colour. THIRD TuNIc,—The third tunic of the eye is the retina, which is prolonged forwards to the lens by the zonuwla ciliaris. Dissection.—If after the preceding dissection the choroid membrane be carefully raised and removed, the eye being kept under water, the retina may be seen very distinctly. The Retina is composed of three layers :— External or Jacob’s membrane, Middle, Nervous membrane, Internal, Vascular membrane. Jacob’s membrane is extremely thin, and is seen as a flocculent film when the eye is suspended in water. Examined by the microscope, it is found to be composed of cells having a tesselated arrangement. Dr. Jacob considers it, to be a serous membrane. The Nervous membrane is the expansion of the optic nerve, and forms a thin semi-transparent bluish white layer, which envelopes the vitreous humour, and extends forwards to the commencement of the ciliary processes, where it terminates by an abrupt scalloped margin. According to Treviranus, this layer'is composed of cylindrical fibres, which proceed from the optic nerve and bend abruptly inwards, near their termination, to form the internal papillary layer, which lies in contact with the hyaloid membrane ; each fibre constituting by its ex- tremity a distinct papilla. The Vaseular membrane consists of the ramifications of a minute artery, the arteria centralis retinze, and its accompanying vein ; the artery pierces the optic nerve, and enters the globe of the eye through the porus opticus, in the centre of the lamina cribrosa. This artery may be seen very distinctly by making a transverse section of the eyeball. Its branches are continuous anteriorly with the zonula ciliaris. The vascular layer forms distinct sheaths for the ner- yous papille, which constitute the inner surface of the retina. In the centre of the posterior part of the globe of the eye the retina presents a circular spot, which is called the foramen of Soemmering ;* * Samuel Thomas Soemmering is celebrated for the beautiful and accurate 500 ZONULA CILIARIS. it is surrounded by a yellow halo, the limbus luteus, and is frequently obscured by an elliptical fold of the retina, which, from its constancy of appearance, has been regarded as a normal condition of the mem- brane. The term foramen is misapplied to this spot, for the vascular layer and the membrana Jacobi are continued across it; the nervous substance alone appearing to be deficient. It exists only in animals having the axis of the eyeballs parallel with each other, as man, quadrumana, and some saurian reptiles, and is said to give passage to a small lymphatic vessel. Fig. 155.* wl tg jt Ni The Zonula ciliaris (zonula. of Zinn)+ s a thin vascular ayer, which connects the anterior margin of the retina with the anterior surface of the lens near its circumference. It presents upon its sur- face a number of small folds corresponding with the ciliary processes, between which they are received. These processes are arranged in the form of rays around the lens, and the spaces between them are plates which accompany his works. The account ‘* De Foramine Centrali Re- tine Humans, Limbo Luteo cincto,’’ was published in 1779, in the Com- mentationes Soc. Reg. Scient. Gottingensis. * The posterior segment of a transverse section of the globe of the eye, seen from within. 1. The divided edge of the three tunics. The membrane covering the-whole internal surface is the retina. 2. The entrance of the optic nerve with the arteria centralis retinze piercing its centre. 3, 3. The ramifica- tions of the arteria centralis. 4. The foramen of Soemmering, in the centre of the axis of the eye ; the shade from the sides of the section obscures the limbus luteus which surrounds it. 5. A fold of the retina, which generally obscures the foramen of Soemmering after the eye has been opened. + John Gottfried Zinn, professor of Anatomy in Gottingen; his “‘ Descriptio Anatomica Oculi Humani,’’ was published in 1755; with excellent plates. It was republished by Wrisberg in 1780. ra aes gril o= AQUEOUS HUMOUR,—CRYSTALLINE HUMOUR, 501 stained by the pigmentum nigrum of the ciliary processes. They derive their vessels from the vascular layer of the retina. The under surface of the zonula is in contact with the hyaloid membrane, and around the lens forms the anterior fluted wall of the canal of Petit. The connection between these folds and the ciliary processes may be very‘easily demonstrated by dividing an eye transversely into two portions, then raising the anterior half, and allowing the vitreous humour to separate from its attachment by its own weight. The folds of the zonula will then be seen to be drawn out from between the folds of the ciliary processes. Humovurs.—The Aqueous humour is situated in the anterior and posterior chambers of the eye ; it is a weakly albuminous fluid, having an alkaline reaction, and a specific gravity very little greater than dis- tilled “water. According to Petit, it scarcely exceeds four or five grains in weight. The anterior chamber is the space intervening between the cornea in front, and the iris and pupil behind. The posterior chamber is the narrow space, less than half a line in depth,* bounded by the posterior surface of the iris and pupil ii in front, and by the ciliary processes, zonula ciliaris, and lens behind. The two chambers are lined by a thin layer, the secreting membrane of the aqueous humour. The Vitreous humour forms the principal bulk of the globe of the eye. Itis an albuminous fluid resembling the aqueous humour en- closed in a delicate membrane, the hyaloid, which sends processes into its interior, forming areole in which the humour is retained. A small artery may sometimes be traced through the centre of the vitreous humour to the capsule of the lens; it is surrounded by a tubular sheath of the hyaloid membrane. This vessel is easily inject- ed in the fetus. The Crystalline humour or lens is situated immediately behind the pupil, and is surrounded by the ciliary processes which slightly over- lap its margin. It is more convex on the posterior than on the anterior surface, and is embedded in the anterior part of the vitreous humour, from which it is separated by the hyaloid membrane. It is invested by a peculiarly transparent and elastic membrane, the capsule of the lens, which contains a small quantity of fluid called liquor Morgagni,+ and is retained in its place by the attachment of the zonula ciliaris. Dr. Jacob is of opinion that the lens is connected to its capsule by means of areolar tissue, and that the liquor Morgagni is the result of a cadaveric change. The lens consists of concentric layers, of which the external are * Winslow and Lieutaud thought the iris to be in contact with the lens ; it frequently adheres to the capsule of the latter in iritis. The depth of the pos- terior chamber is greater in old than in young persons. + John Baptist Morgagni was born in 1682. He was appointed Professor of Medicine in Bologna, and published the first part of his ‘‘ Adversaria Ana- tomica,’’ in 1706. He died in 1771. 502 LENS.—CANAL OF PETIT. “soft, the next firmer, and the central form a hardened nucleus. These layers are best demonstrated by boiling, or by immersion in alcohol, when they separate easily from each other. Another division of the lens takes place at the same time: it splits into three triangular segments, which have the sharp edge directed towards the centre, and the base towards the circumference. The concentric lamelle are com- posed of minute parallel fibres, which are united with each other by means of scalloped borders; the convexity on the one border fitting accurately the concave scallop upon the other. Immediately around the circumference of the lens is a triangular canal, the canal of Petit,* about a line and a half in breadth. It is bounded in front by the flutings of the zonula ciliaris; behind by the hyaloid membrane; and within by the border of the lens. The Vessels of the globe of the eye are the long, and short, and anterior ciliary arteries, and the arteria centralis retine. The long ciliary arteries, two in number, pierce the posterior part of the scle- rotic, and pass forward on each side, between that membrane and the choroid, to the ciliary ligament, where they divide into two branches, which are distributed to the iris. The short ciliary arteries pierce the posterior part of the sclerotic coat, and are distributed to the middle layer of the choroid membrane. The anterior ciliary are branches of the muscular arteries. They enter the eye through the anterior part of the sclerotic, and are distributed to the iris, It is the increased number of these latter arteries in iritis that gives rise to the peculiar red zone around the circumference of the cornea. The arteria centralis retin enters the optic nerve at about half an inch from the globe of the eye, and passing through the porus opticus is distributed upon the inner surface of the retina, forming its vascular layer; one branch pierces the centre of the vitreous humour, and sup- plies the capsule of the lens. The Nerves of the eyeball are the optic, two ciliary nerves from the nasal branch of the ophthalmic, and the ciliary nerves from the ciliary ganglion. Observations.—The sclerotic is a tunic of protection, and the cornea a medium for the transmission of light. The choroid supports the vessels destined for the nutrition of the eye, and by its pig- mentum nigrum absorbs all loose and scattered rays that might confuse the image impressed upon the retina. The iris, by means of its powers of expansion and contraction, regulates the quantity of light admitted through the pupil. If the iris be thin, and the rays of light pass through its substance, they are immediately absorbed by the’ uvea; and if that layer be insufficient, they are taken up by the black pigment of the ciliary processes. In Albinoes, where there is an absence of pig- mentum nigrum, the rays of light traverse the iris and even the scle- rotic, and so overwhelm the eye with light, that sight is destroyed, * John Louis Petit, a celebrated French surgeon: he published several = cal ty anatomical Essays, in the early part of the 18th century. He led in 1750, EYEBROWS.—EYELIDS. 503 except in the dimness of evening or at night. In the manufacture of optical instruments care is taken to colour their interior black with the same object, the absorption of scattered rays. The transparent lamellated cornea and the humours of the eye have for their office the refraction of the rays in such proportion as to direct the image in the most favourable manner upon the retina. Where the refracting medium is too great, as in over convexity of the cornea and lens, the image falls short of the retina (myopia, near-sightedness) ; and where it is too little the image is thrown beyond the nervous membrane (presbyopia, far-sightedness). These conditions are recti- fied by the use of spectacles, which provide a differently refracting mg externally to the eye, and thereby correct the transmission of ight. APPENDAGES OF THE EYE. The Appendages of the eye (tutamina oculi) are the eyebrows, eye lids, eyelashes, conjunctiva, caruncula lachrymalis, and the lachryma apparatus. _ The Eyebrows (supercilia) are two projecting arches of integument covered with short thick hairs, which form the upper boundary of the orbits. They are connected beneath with the orbiculares, occipito- frontales, and corrugatores superciliorum muscles; their use is to shade the eyes from a too vivid light, or protect them from particles of dust and moisture floating over the forehead. The Eyelids (palpebre) are two valvular layers placed in front of the eye, serving to defend it from injury by their closure. When drawn open they leave between them an elliptical space, the angles of which are called canthi. The outer canthus is formed by the meeting of the two lids at an acute angle. The inner canthus is prolonged for a short distance inwards towards the nose, and a triangular space is left between the lids in this situation, which is called the lacus lachry- malis. At the commencement of the lacus lachrymalis upon each of the two lids is a small angular projection, the /achrymal papilla or tubercle; and at the apex of each papilla a small orifice (punctum lachrymale), the commencement of the lachrymal canal. The eyelids have, entering into their structure, integument, orbicu- laris muscle, tarsal cartilages, Meibomian glands, and conjunctiva. The tegumentary areolar tissue of the eyelids is remarkable for its looseness and for the entire absence of adipose substance ; it is parti- cularly liable to serous infiltration. The fibres of the orbicularis muscle covering the eyelids, are extremely thin and pale. The Tarsal cartilages are two thin lamelle of fibro-cartilage about an inch in length, which give form and support to the eyelids. The superior is of a semilunar form, about one-third of an inch in breadth at its middle, and tapering to each extremity. Its lower border is broad and flat, its upper is thin, and gives attachment to the levator palpebree and to the fibrous membrane of the lids. 504 MEIBOMIAN GLANDS.—CONJUNCTIVA. The Inferior fibro-cartilage is an elliptical band, narrower than the superior, and situated in the substance of the lower lid. Its upper border is flat, and corresponds with the flat edge of the upper cartilage. The lower is held in its place by the fibrous membrane. At the inner canthus the tarsal cartilages terminate at the commencement of the lacus lachrymalis, and are attached to the margin of the orbit by the tendo oculi. At their outer extremity they terminate at a short dis- tance from the angle of the canthus, and are retained in their position by means of a decussation of the fibrous structure of the broad tarsal ligament, called the external palpebral ligament. The Fibrous membrane of the lids is firmly attached to the perios- teum, around the margin of the orbit, by its circumference, and to the tarsal cartilages by its central margin. It is thick and dense on the outer half of the orbit, but becomes thin to its inner side. Its use is to retain the tarsal cartilages in their place, and give support to the lids ; hence it has been named the broad tarsal ligament. The Meibomian glands* are embedded in the internal surface of the cartilages, and are very distinctly seen on examining the inner aspect of the lids.) They have the appearance of parallel strings. of pearls, about thirty in number in the upper cartilage, and somewhat fewer in the lower; they open by minute foramina upon the edges of the lids. They correspond in length with the breadth of the cartilage, and are consequently longer in the upper than in the lower lid. Each gland consists of a single lengthened follicle or tube, into which a number of small clustered follicles open ; the latter are so numerous as almost to conceal the tube by which the secretion is poured out upon the margin of the lids. Occasionally an arch is formed between two of them, and produces a very graceful appearance. The edges of the eyelids are furnished with a triple row of long thick hairs, which curve upwards from the upper lid, and downwards from the lower, so that they may not interlace with each other in the closure of the eyelids, and prove an impediment to the opening of the eyes. These are the eyelashes (cilia), important organs of defence to the sensitive surface of so delicate an organ as the eye. The Conjunctiva is the mucous membrane of the eye. It covers the whole of its anterior surface, and is then reflected upon the lids so as to form their internal layer. The duplicatures formed between the globe of the eye and the lids are called the superior and inferior palpe- bral sinuses, of which the former is much deeper than the inferior. Where it covers the cornea the conjunctiva is very thin and closely adherent, and no vessels can be traced into it. Upon the sclerotica it is thicker and less adherent, but upon the inner surface of the lids is very closely connected, and is exceedingly vascular. It is continuous with the general gastro-pulmonary mucous membrane and sympathises in its affections, as may be observed in various diseases. From the surface of the eye it may be traced through the lachrymal ducts into * Henry Meibomius, ‘‘ de Vasis Palpebrarum Novis,’’ 1666. Te eee. e oe LACHRYMAL APPARATUS. P 505 the lachrymal-gland ; along the edges of the lids it is continuous with the mucous lining of the Meibomian glands, and at the inner angle of the eye may be followed through the lachrymal canals into the lachry- mal sac, and thence downwards through the nasal duct into the infe- rior meatus of the nose. The Caruncula lachrymalis is the small reddish body which occupies the lacus lachrymalis at the inner canthus of the eye. In health it presents a bright pink tint ; in sickness it loses its colour and becomes pale. It consists of an assemblage of follicles similar to the Meibomian glands, embedded in a fibro-cartilaginous tissue, and is the source of the whitish secretion which so constantly forms at the inner angle of the eye. It is covered with minute hairs which are sometimes so long as to be distinctly visible to the naked eye. Immediately to the outer side of the caruncula is a slight duplica- ture of the conjunctiva, called plica semilunaris, which contains a minute plate of cartilage, and is the rudiment of the third lid of animals, the membrana nictitans of birds. Vessels and nerves. — The palpebre are supplied internally with arteries from the ophthalmic, and externally from the facial and transverse facial. Their nerves are branches of the fifth and of the facial. LACHRYMAL APPARATUS, The Lachrymal apparatus consists of the lachrymal gland with its excretory ducts ; the puncta lachrymalia, and lachrymal canals ; 3; the lachrymal sac and nasal duct. The Lachrymal gland is situated at the upper and outer sad of the orbit, and consists of two portions, orbital and palpebral. The orbital portion, about three quarters of an inch in length, is flattened and oval in shape, and occupies the lachrymal fossa in the orbital plate of the frontal bone. It is in contact superiorly with the perios- teum, with which it is closely connected by its upper and convex surface ; by its inferior or concave surface it is in relation with the globe of the eye, and the superior and external rectus; and by its anterior border with the broad tarsal ligament. By its posterior border it receives its vessels and nerves. The palpebral portion, smaller than the preceding, is situated in the upper eyelid, extending downwards to the superior margin of the tarsal cartilage. It is con- tinuous with the orbital portion above, and is enclosed in an inyest- ment of dense fibrous membrane. The secretion of the lachrymal gland is conveyed away by ten or twelve small ducts which run for a short distance beneath the conjunctiva, and open upon its surface by a series of pores about one-twentieth of an inch apart, situated in a curved line a little above the upper border of the tarsal cartilage. Lachrymal canals. —The lachrymal canals commence at the minute openings, puncta lachrymalia, seen upon the lachrymal papillz of the lids at the outer extremity of the lacus lachrymalis, and proceed in- 506 ORGAN OF HEARING, wards to the lachrymal sac, where they terminate beneath a valvular semilunar fold of the lining membrane of the sac. The superior duct at first ascends, and then turns suddenly inwards towards the sac, forming an abrupt angle. The inferior duct forms the same kind of angle, by descending at first, and then turning abruptly inwards. They are dense and elastic in structure, and remain constantly open, so that they act like capillary tubes in absorbing the tears from the surface of the eye. The two fasciculi of the tensor tarsi muscle are inserted into these ducts, and serve to draw them inwards. The Lachrymal sac is the upper extremity of the nasal duct, and is scarcely more dilated than the rest of the canal. It is lodged in the groove of the lachrymal bone, and is often distinguished internally from the nasal duct by a semilunar or circular valye. The sac consists of mucous membrane, but is covered in and retained in its place by a fibrous expansion, derived from the tendon of the orbicularis, which is inserted into the ridge on the lachrymal bone; it is also covered by the tensor tarsi muscle, which arises from the same ridge, and in its action upon the lachrymal canals may serve to compress the, lachrymal sac. The Nasal duct is a short canal about three quarters of an inch in length, directed downwards, backwards, and a little outwards to the inferior meatus of the nose, where it terminates by an expanded orifice. It is lined by mucous membrane, which is continuous with the con- junctiva above, and with the pituitary membrane of the nose be- low. Obstruction from inflammation and suppuration of this duct constitutes the disease called fistula lachrymalis. Vessels and nerves.— The lachrymal gland is supplied with blood by the lachrymal branch of the ophthalmic artery, and with nerves by the lachrymal branch of the ophthalmic and orbital branch of the superior maxillary. pat THE ORGAN OF HEARING. The apparatus of hearing is composed of three parts ; the external ear, middle ear or tympanum, and internal ear or labyrinth. The EXTERNAL EAR consists of two portions, the pinna and meatus; the former representing a kind of funnel which collects the vibrations of the atmosphere, called sounds, and the latter a tube which conveys the vibrations to the tympanum. The Pinna presents a number of folds and hollows upon its surface, which have different names assigned to them. Thus the external folded margin is called the helia (24.2, a fold). The elevation parallel to and in front of the helix is called antihelia (avri, opposite). The pointed process, projecting like a valve over the opening of the ear from the face, is called the tragus (redyos; a goat), probably from being sometimes covered with bristly hair like that of a goat; anda tubercle opposite to this is the antitragus. The lower dependent and es —_ ANATOMY OF THE PINNA. 507 fleshy portion of the pinna, is the /obulus. The space between the helix and antihelix is named the Jossa innominata. Another depres-_ sion is observed at the upper extremity of the antihelix, which bifur- cates and leaves a triangular space between its branches called the scaphoid fossa; and the large central space to which all the channels converge is the concha, which opens directly into the meatus. The pinna is composed of integument, fibro-cartilage, ligaments, and muscles, The Integument is thin, contains an abundance of sebaceous follicles, and is closely connected with the fibro-cartilage. The Fibro-cartilage gives form to the pinna, and is folded so as to produce the various convexities and grooves which have been described upon its surface. The heléa commences in the concha, and partially di- vides that cavity into two parts ; on its anterior border is a tubercle for the attachment of the attrahens aurem muscle, and a little above thisa small vertical fissure, the fisswre of the helix. The termination of the helix and antihelix forms a lengthened process, the processus caudatus, which is separated from the concha by an extensive fissure. Upon the anterior surface of the tragus is another fissure, the fissure of the _ tragus, and in the lobulus the fibro-cartilage is wholly deficient. The fibro-cartilage of the meatus, at the upper and anterior part of the cylinder, is divided from the concha by a fissure which is closed in the entire ear by ligamentous fibres ; it is firmly attached at. its termina- tion to the processus auditorius. The Ligaments of the external ear are those which attach the pinna to the side of the head, viz. the anterior, posterior, and ligament of the tragus; and those of the fibro-cartilage which serve to preserve its folds and connect the opposite margins of the fissures. The latter are two in number, the ligament between the concha and the processus caudatus, and the broad ligament which extends from the upper mar- gin of the fibro-cartilage of the tragus to the helix, and completes the meatus. The proper Muscles of the pinna are the— Major helicis, Minor helicis, Tragicus, Antitragicus, Transversus auricule. The Major helicis is a narrow band of muscular fibres situated upon the anterior border of the helix, just above the tragus. The Minor helicis is placed upon the posterior border of the helix, at its commencement in the fossa of the concha. The Tragicus is a thin quadrilateral layer of muscular fibres, situated upon the tragus. The Axtitragicus arises from the antitragus, and is inserted into the posterior extremity, or processus caudatus of the helix. 508 MEATUS AUDITORIUS.—TYMPANUM. ~ The Transversus auricule, partly tendinous and partly muscular, extends transversely from the convexity of the concha to that of the helix, on the posterior surface of the pinna. These muscles are rudimentary in the human ear, and deserve only the title of muscles in the ears of animals. Two other muscles are described by Mr. Tod,* the obliquus auris and contractor meatis, or trago-helicus, The Meatvus AvupIrTorivs is a canal, partly cartilaginous and partly osseous, about an inch in length, which extends inwards and a little forwards from the concha to the tympanum, It is narrower in the middle than at each extremity, forms an oval cylinder, the long diameter being vertical, and is slightly curved upon itself, the con- cavity looking downwards. It is lined by an extremely thin pouch of epidermis, which, when withdrawn after maceration, preserves the form of the meatus. Some stiff short hairs are also found in its interior, which stretch across the tube, and prevent the ingress of insects and dust. Beneath the epi- dermis are a number of small ceruminous follicles, which secrete the wax of the ear, Vessels and Nerves.—The pinna is plentifully supplied with arteries ; by the anterior auricular from the temporal, and by the posterior auricular from the external carotid. Its Nerves are derived from the anterior auricular of the fifth, the posterior auricular of the facial, and the auricularis magnus of the cer- vical plexus. MIDDLE EAR OR TYMPANUM. The tympanum is an irregular bony cavity, compressed from without inwards, and situated within the petrous bone. It is bounded ezter- nally by the meatus and membrana tympani ; internally by the base of the petrous bone; and in its circwmference by the petrous bone and mastoid cells. The Membrana tympani is a thin and semi-transparent membrane of an oval shape, the long diameter being vertical. It is inserted into a groove around the circumference of the meatus near its termination, and is placed obliquely across the area of that tube, the direction of the obliquity being downwards and inwards. It is concave towards the meatus, and convex towards the tympanum, and is composed of three layers, an eaternal epidermic, middle fibrous and muscular, and inxternal mucous, derived from the mucous lining of the tympanum. The tympanum contains three small bones, ossicula audittis, viz., the malleus, incus, and stapes. * “The Anatomy and Physiology of the Organ of Hearing,’? by David Tod, 1832. a Bins i Raa Se oar lee BONES OF THE TYMPANUM. 509 The Malleus (hammer) consists of a head, neck, handle (manu- brium), and two processes, long (processus gracilis), and short (processus brevis). 'The manubrium is connected to the membrana tympani by its whole length extending to below the central point of that mem- brane. It lies beneath its mucous layer, and serves as a point of attachment to which the radiating fibres of the fibrous layer converge. The long process descends to a groove near the fissura Glaseri, and gives attachment to the laxator tympani muscle. Into the short pro- cess is inserted the tendon of the tensor tympani, and the head of the bone articulates with the incus. Fig. 156.* * A diagram of the ear. p. The pinna. ¢. The tympanum. J. The labyrinth. 1, The upper part of the helix. 2, The antihelix. 3. The tragus. 4, The antitragus. 5. Thelobulus. 6. The concha. 7. The upper part of the fossa innominata. 8. The meatus. 9. The membrana tympani, divided by the sec- tion. 10. The three little bones, ona area of the tympanum, malleus, incus, and ee ; the foot of the stapes blocks up the fenestra ovalis upon the inner wall of the tympanum. 11. The promontory. 12. The fenestra rotunda; the dark opening above the ossicula leads into the mastoid cells. 13. The Eus- tachian tube; the little canal upon this tube contains the tensor tympani mus- cle in its passage to the tympanum. 14. The vestibule. 15. The e semi- circular canals, horizontal, poreoc and oblique. 16. The ampulle upon the perpendicular and horizontal canals. 17. The cochlea. 18. A de- pression between the convexities of the two tubuli which communicate with the tympanum and vestibule ; the one is the scala tympani, terminating at 12; the other is the scala vestibuli. + 510 MUSCLES OF THE TYMPANUM. ’ The Incus (anvil) is named from an imagined resemblance to an anvil. It has also been likened to a bicuspid tooth, having one root longer than, and widely separated from the other. It consists of two processes, which unite nearly at right angles, and at their junction form a flattened body, to articulate with the head of the malleus. The short process is attached to the margin of the opening of the mastoid cells by means of a short ligament ; the long process descends nearly parallel with the handle of the malleus, and curves inwards, near its termination. At its extremity is a small globular projection, the os orbiculare, which in the fetus is a distinct bone, but becomes anchylosed to the long process of the incus in the adult; this process articulates with the head of the stapes. The Stapes is shaped like a stirrup, to which it bears a close resem- blance. Its head articulates with the os orbiculare, and the two branches are connected by their extremities with a flat oval-shaped plate, representing the foot of the stirrup. The foot of the stirrup is received into the fenestra ovalis, to the margin of which it is con- nected by means of a circular ligament ; it is in contact, by its sur- face, with the membrana vestibuli, and is covered in by the mucous lining of the tympanum. The neck of the stapes gives attachment to the stapedius muscle. The ossicula auditis are retained in their position and moved upon themselves by means of ligaments and muscles. The Ligaments are three in number ; the ligament of the head of the malleus, which is attached superiorly to the upper wall of the tympanum ; the ligament of the incus, a short and thick band, which serves to attach the extremity of the short process of that bone to the margin of the opening of the mastoid cells ; and the circular ligament which connects the margin of the foot of the stapes with the circum- ference of the fenestra ovalis. These ligaments have been described as muscles, by Mr. Tod, under the names of superior capitis mallei, obliquus incudis externus posterior, and musculus vel structura sta- pedii inferior. The Muscles of the tympanum are four in number, the— Tensor tympani, Laxator tympani, Laxator tympani minor, Stapedius. The Tensor tympani (musculus internus mallei) arises from the spinous process of the sphenoid, from the petrous portion of the tem- poral bone, and from the Eustachian tube, and passes forwards in a distinct canal, separated from the tube by the processus cochleariformis, to be inserted into the handle of the malleus, immediately below the commencement of the processus gracilis. The Lawxator tympani (musculus externus mallei) arises from the FORAMINA OF THE TYMPANUM. 511 spinous process. of the sphenoid bone, and passes through an opening in the fissura Glaseri, to. be imserted into the long process of the malleus. This is regarded as a ligament by some anatomists. The Laaator tympani minor arises from the upper margin of the meatus, and is inserted into the handle of the malleus, near the pro- cessus brevis. This is regarded as a ligament by some anatomists. The Stapedius arises from the interior of the pyramid, and escapes from its summit to be inserted into the neck of the stapes. Foramina.—The openings in the tympanum are ten in number, five large and five small ; they are— Large Openings. Small Openings. Meatus auditorius, Entrance of the chorda tympani, Fenestra ovalis, Exit of the chorda tympani, Fenestra rotunda, For the laxator tympani, Mastoid cells, For the tensor tympani, Eustachian tube. For the stapedius. The opening of the meatus auditorius has been previously described. The Fenestra ovalis (fenestra vestibuli), is a reniform opening, situated at the bottom of a small oval fossa (the pelvis ovalis), in the upper. part of the inner wall of the tympanum, directly opposite the meatus. The long diameter of the fenestra is directly horizontally, and its convex borders upwards. It is the opening of communication between the tympanum and the vestibule, and is closed by the foot of the stapés and by the lining membranes of both cavities. The Fenestra rotunda (fenestra cochlex) is somewhat triangular in its form, and situated in the inner wall of the tympanum, below and rather posteriorly to the fenestra ovalis, from which it is separated by a bony elevation, called the promontory. It serves to establish a com- munication between the tympanum and the cochlea. In the fresh subject it is closed by a proper membrane (m. tympani secundaria), as well as by the lining of both cavities. The Mastoid cells are numerous, and occupy the whole of the interior of the mastoid process, and part of the petrous bone. They communicate by a large irregular opening with the upper and posterior circumference of the tympanum. The Eustachian tube is a canal of communication extending ob- liquely between the pharynx and the anterior circumference of the tympanum. In structure it is partly fibro-cartilaginous and partly osseous, is broad and expanded at its pharyngeal extremity, and narrow and compressed at the tympanum. The smaller openings serve for the transmission of the chorda tym- pani nerve, and three of the muscles of the tympanum. The opening by which the chorda tympani enters the tympanum, is near the root of the pyramid, at about the middle of the posterior wall, 512 FORAMINA OF THE TYMPANUM. The opening of exit for the chorda tympani is at the fissura Glaseri in the anterior wall of the tympanum. The opening for the laxator tympani muscle is also situated in the fissura Glaseri, in the anterior wall of the tympanum. The opening for the tensor tympani muscle is in the tnner wall, im- mediately above the opening of the Eustachian tube. The opening for the stapedius muscle is at the apex of a conical bony eminence, called the pyramid, which is situated on the posterior wall of the tympanum, immediately behind the fenestra ovalis. Directly above the fenestra ovalis is a rounded ridge formed by the projection of the aqueductus Fallopii. Beneath the fenestra ovalis and separating it from the fenestra ro- tunda is the promontory, a rounded prominence formed by the projec- tion of the first turn of the cochlea. It is channeled upon its surface by three small grooves, which-lodge the three tympanic branches of Jacobson’s nerve, The Foramina and processes of the tympanum may be arranged, according to their situation, into four groups. 1. In the Eaternal wall is the meatus auditorius, closed by the membrana tympani. 2. In the Inner wall, from above downwards, are the— Opening for the tensor tympani, Ridge of the aqueeductus Fallopii, Fenestra ovalis, Promontory, Grooves for Jacobson’s nerve, Fenestra rotunda. 3. In the Posterior wall are the— Opening of the mastoid cells Pyramid, Opening for the stapedius, Opening for Jacobson’s nerve, Apertura chord (entrance). 4, In the Anterior wall are the— Eustachian tube, Fissura Glaseri, Opening for the laxator tpmpani, Apertura chord (exit). The tympanum is lined by a vascular mucous membrane, which in- vests the ossicula and chorda tympani, and forms the internal layer of the membrana tympani. From the tympanum it is reflected into the A LABYRINTH.— VESTIBULE. 513 mastoid cells, which it lines throughout, and passes through the Eus- tachian tube to become continuous with the mucous membrane of the pharynx. Vessels and Nerves.—The Arteries of the tympanum are derived from the internal maxillary, internal carotid, and posterior auricular. Its Nerves are—1l. Minute branches from the facial, which are distributed to the stapedius muscle. 2.°The chorda tympani, which leaves the facial nerve near the stylo-mastoid foramen, and arches upwards to enter the tympanum at the root of the pyramid; it then passes forwards between the handle of the malleus and long process of the incus, to its proper opening in the fissura Glaseri. 3. The tym- panic branches of Jacobson’s nerve, which are distributed to the mem- branes of the fenestra ovalis and fenestra rotunda, and to the Eusta- chian tube, and form a plexus by communicating with the carotid plexus, otic ganglion, and Vidian nerve. 4. A filament from the otic ganglion to the tensor tympani muscle. INTERNAL EAR, The Internal ear is called labyrinth, from the complexity of its com- munications ; it consists of a membranous and an osseous portion. The osseous labyrinth presents a series of cavities which are channeled through the substance of the petrous bone, and is situated between the cavity of the tympanum and the meatus auditorius internus. It is divisible into the— Vestibule, Semicircular canals, Cochlea. The VESTIBULE is a small three-cornered cavity, compressed from without inwards, and situated immediately within the inner wall of the tympanum. The three corners which are named ventricles or cornua are placed, one anteriorly, one superiorly, and one posteriorly. The Anterior ventricle receives the oval aperture of the scala vesti- buli ; the superior, the ampullary openings of the superior and hori- zontal semicircular canals ; the posterior ventricle receives the am- pullary opening of the oblique semicircular canal, the common aperture of the oblique and perpendicular canals, the termination of the hori- zontal canal, and the aperture of the aqueductus vestibuli. In the anterior ventricle is a small depression, which corresponds with the posterior segment of the cul de sac of the meatus auditorius internus ; it is called the fovea hemispherica, and is pierced by a cluster of small openings, the macula cribrosa. In the superior ventricle of the vesti- bule is another small depression, the fovea elliptica, which is separated from the fovea hemispherica by a projecting crest, the eminentia pyramidalis. The latter is pierced by numerous minute openings for 2L 514 SEMICIRCULAR CANALS. the passage of nervous filaments. The posterior ventricle presents a third small depression, the fovea sulciformis, which leads upwards to the ostium aquaductus vestibuli. The internal wall of the vestibule corresponds with the bottom of the cul de sac of the meatus auditorius internus, and is pierced by numerous small openings for the trans- mission of nervous filaments. In the eaternal or tympanic wall is the reniform opening of the fenestra ovalis (fenestra vestibuli), the margin of which presents a prominent rim towards the cavity of the vestibule. The openings of the vestibule may be arranged, like those of the tympanum, into large and small. The Large openings are seven in number ; viz. the— Fenestra ovalis, Scala vestibuli, Five openings of the three semicircular canals. The Small openings are the— Aqueeductus vestibuli, Openings for small arteries, Openings for branches of the auditory nerve. The Fenestra ovalis has already been described ; it is the opening into the tympanum. The opening of the scala vestibuli is the oval termination of the ves- tibular canal of the cochlea. The Aqueductus vestibult (canal of Cotunnius) is the commencement of the small canal which opens under the osseous scale upon the pos- terior surface of the petrous bone. It gives passage to a process of membrane which is continuous internally with the lining membrane of the vestibule, and externally with the dura mater, and to a small vein. The Openings for the arteries and nerves are situated in the internal wall of the vestibule, and correspond with the termination of the meatus auditorius internus. i The SEMIcIRCULAR CANALS are three bony passages communi- cating with the vestibule, into which they open by both extremities. Near one extremity of each of the canals is a remarkable dilatation of its cavity, which is called the ampulla (sinus ampullaceus). The superior, or perpendicular canal (canalis semicircularis verticalis supe- rior), is directed transversely across the petrous bone, forming a pro- jection upon the anterior face of the latter. It commences by means of an ampulla in the superior ventricle of the vestibule, and terminates posteriorly by joining with the oblique, and forming a common canal, which opens into the upper part of the posterior ventricle. The middle or oblique canal (canalis semicircularis verticalis posterior) cor- responds with the posterior part of the petrous portion of the temporal COCHLEA.—MODIOLUS. 515 bone: it commences by an ampullary dilatation in the posterior ven- tricle, and curves nearly perpendicularly upwards to terminate in the common canal. In the ampulla of this canal are numerous minute openings for nervous filaments. The inferior or horizontal canal (canalis semicircularis horizontalis) is directed outwards towards the - base of the petrous bone, and is shorter than the two preceding. It commences by an ampullary dilatation in the superior ventricle, and terminates in the posterior ventricle. The Cocuxea (snail Fig. 157.* shell) forms the anterior portion of the labyrinth, corresponding by its apex with the anterior wall of the petrous bone, and by its base with the anterior de- pression at the bottom of the cul de sac of the meatus auditorius in- ternus. It consists of an osseous and gradual- ly tapering canal, about one inch and a half in length, which makes two turns and a half spirally around a central axis called the modiolus. The central axis or modiolus is large near its base where it corre- sponds with the first turn of the cochlea, and diminishes in diameter towards its extremity. At its base it is pierced by numerous minute openings which transmit the filaments of the cochlear nerve. These openings are disposed in a spiral manner: hence they have received from Cotunniust the name of tractus spiralis foraminu- * The cochlea divided parallel with its axis, through the centre of the modi- olus. After Breschet. 1. The modiolus. 2. The infundibulum in which the modiolus terminates. 3, 3. The cochlear nerve, sending its filaments through the centre of the modiolus. 4, 4. The scala tympani of the first turn of the cochlea. 5, 5. The scala vestibuli of the first turn; the septum between 4 and 5 is the lamina spiralis ; a filament of the cochlear nerve is seen passing be- tween the layers of the lamina to be distributed upon the membrane which in- vests the lamina. 7. The membranous | tev of the lamina spiralis. 8. Loops formed by the filaments of the cochlear nerve on the lamina spiralis. 9, 9. Scala tympani of the second turn of the cochlea. 10, 10. Scala vestibuli of the second turn; the septum between the two is the lamina spiralis. 11. The remaining half turn of the scala vestibuli ; the dome placed over this half turn is the cupola ; a line leads from the numeral to the remaining half turn of the scala tympani. The lamina of bone which forms the floor of the scala vestibuli curves spirally round to constitute the infundibulum (2). 14. The helicotrema through which a bristle is passed ; its lower extremity issues from the scala tympani of the middle turn of the cochlea. _ ; + Dominico Cotunnius, an Italian physician ; his dissertation “‘ De Aquze- ductibus Auris Humane Internz’’ was published at Naples in 1761. vA 516 SCALA TYMPANI ET VESTIBULI. lentus. The modiolus is everywhere traversed in the direction of its length by minute canals, which proceed from the tractus spiralis foraminulentus, and terminate upon the sides of the modiolus, by opening into the canal of the cochlea or upon the surface of its Jamina spiralis. The central canal of the tractus spiralis foraminulentus is larger than the rest, and is named the tubulus centralis modioli ; it is continued onwards to the extremity of the modiolus, and transmits a nerve and small artery, the arteria centralis modioli. The interior of the canal of the cochlea is partially divided into two passages (scale) by means of a thin and porous lamina of bone (zonula ossea laminz spiralis), which is wound spirally around the modiolus in the direction of the canal. This bony septum extends for about two-thirds across the diameter of the canal, and in the fresh subject is prolonged to the opposite wall by means of a membranous layer, so as to constitute a complete partition, the lamina spiralis. The osseous lamina spiralis consists of two thin lamellz of bone, between which, and through the perforations on their surfaces, the filaments of the cochlear nerve reach the membrane of the cochlea. At the apex of the cochlea the lamina spiralis terminates by a pointed, hook-shaped process, the hamulus laminz spiralis. The two scale of the cochlea, which are com- pletely separated throughout their length in the living ear, communicate superiorly over the hamulus laminz spiralis by means of an opening common to both, which has been termed by Breschet helico-trema (2as%, tAicow volvere—-reyux). Inferiorly, one of the two scale, the scala vestibuli, terminates by means of an oval aperture in the anterior ventricle of the vestibule; while the other, the scala tympani, becomes somewhat expanded, and opens into the tympanum through the fenestra. rotunda (fenestra cochlee). Near the termi- nation of the scala tympani is the small opening of the aqueeductus cochleze: The internal surface of the osseous labyrinth is lined by a fibro- serous membrane, which is analogous to the dura mater in performing the office of a periosteum by its exterior, whilst it fulfils the purpose of a serous membrane by its internal layer, secreting a limpid fluid, the aqua labyrinthi (liquor Cotunnii), and sending a reflection inwards upon the nerves distributed to the membranous labyrinth. In the cochlea the membrane of the labyrinth invests the two surfaces of the bony lamina spiralis, and being continued from its border across the diameter of the canal to its outer wall, forms the membranous lamina spiralis, and completes the separation between the scala tympani and scala vestibuli. The fenestra ovalis and fenestra rotunda are closed by an extension of this membrane across them, assisted by the mem- brane of the tympanum and a proper intermediate layer. Besides lining the interior of the osseous cavity, the membrane of the laby- rinth sends two delicate processes along the aqueducts of the vestibule and cochlea to the internal surface of the dura mater, with which they are continuous. These processes are the remains of a communication MEMBRANOUS LABYRINTH. 517 originally subsisting between the dura mater and the cavity of the labyrinth.t Fig. 158.* The MEMBRANOUS LABY- RINTH is smaller in size, but a perfect counterpart with re- spect to form, of the vestibule and semicircular canals. It consists of a small elongated sac, sacculus communis (utri- culus communis); of three semi- circular membranous canals, which correspond with the osse- ous canals, and communicate with the sacculus communis; and of a small round sac (sac- culus proprius), which occupies the anterior ventricle of the vestibule, and lies in close con- tact with the external surface of the sacculus communis. The * The labyrinth of the left ear, laid open in order to show its cavities and the membranous labyrinth. After Breschet. 1. The cavity of the ves- tibule, opened from its anterior aspect in order to show the three-cornered form of its interior, and the membranous labyrinth which it contains. The figure rests upon the common saccule of the membranous labyrinth,—the sac- culus communis. 2. The ampulla of the superior or perpendicular semicir- eular canal, receiving a nervous fasciculus from the superior branch of the vestibular nerve, 3. 4. The superior or perpendicular canal with its contained membranous canal. 5. The ampulla of the inferior or horizontal semicir- cular canal, receiving a nervous fasciculus from the superior branch of the ves- tibular nerve. 6. The termination of the membranous canal of the horizontal semicircular canal in the sacculus communis. 7. The ampulla of the middle or oblique semicircular canal, receiving a nervous fasciculus from the inferior branch of the vestibular nerve. 8. The oblique semicircular canal with its membranous canal. 9. The common canal, resulting from the union of the perpendicular with the oblique semicircular canal. 10. The membranous common canal terminating in the sacculus communis. 11. The otoconite of the sacculus communis seen through the membranous parietes of that sac. A nervous fasciculus from the inferior branch of the vestibular nerve is seen to be distributed to the sacculus communis near the otoconite. The extre- mity of the sacculus above the otoconite is lodged in the superior ventricle of + Cotunnius regarded these processes as tubular canals, through which the superabundant aqua labyrinthi might be expelled into the cavity of the cra- nium. Mr. Wharton Jones, in the article ‘“‘ Organ of Hearing,” in the Cyclopedia of Anatomy and Physiology, also describes them as tubular canals which terminate beneath the dura mater of the petrous bone in a small dilated pouch. In the ear of a man deaf and dumb from birth, he found the termina- tion of the aqueduct of the vestibule of unusually large size in consequence of irregular development. 518 DISTRIBUTION OF THE AUDITORY NERVE. membranous semicircular canals are two-thirds smaller in diameter than the osseous canals. The membranous labyrinth is retained in its position by means of the numerous nervous filaments which are distributed to it from the openings in the inner wall of the vestibule, and is separated from the lining membrane of the labyrinth by the aqua labyrinthi. In structure it is composed of four layers: an external or serous layer, derived from the lining membrane of the labyrinth; a vascular layer, in which an abundance of minute vessels are distributed ; a nervous layer, formed by the expansion of the filaments of the vestibular nerve and an internal and serous membrane, by which the limpid fluid which fills its interior is secreted. Some patches of pigment have been ob- served by Mr. Wharton Jones in the tissue of the membranous laby- rinth of man. Among animals such spots are constant. The membranous labyrinth is filled in its interior with a limpid fluid, first well described by Scarpa, and thence named liquor Scarpze* (endolymph, vitreous humour of the ear), and contains two small cal- careous masses called otoconites. The otoconites (obs, ards xovs, the ear-dust), consist of an assemblage of minute, crystalline particles of car- bonate and phosphate of lime, held together by animal substance, and probably retained in form by a reflection of the lining membrane of the mebranous labyrinth. They are found suspended in the liquor Scarpze ; one in the sacculus communis, the other in the sacculus proprius, from that part of each sac with which the nerves are con- nected, The AUDITORY NERVE divides into two branches at the bottom of the cul de sac of the meatus auditorius internus; a vestibular. nerve, and a cochlear nerve.. The vestibular nerve, the most posterior of the two, divides into three branches, superior, middle, and inferior. The superior vestibular branch gives off a number of filaments which pass through the minute openings of the eminentia pyramidalis and the vestibule, and that below it in the inferior ventricle. 12. The sacculus proprius situated in the anterior ventricle ; its otoconite is seen through its membranous parietes, and a nervous fasciculus derived from the middle branch of the vestibular nerve is distributed to it. The s s around the membranous labyrinth are occupied by the aqua labyrinthi. 13. The first turn of the cochlea; the figure points to the scala tympani. 14. The extre- mity of the scala tympani corresponding with the fenestra rotunda. 15. The lamina spiralis; the figure is situated in the scala vestibuli. 16. The open- ing of the scala vestibuli into the vestibule. 17. The second turn of the cochlea; the figure is placed upon the lamina spiralis, and therefore in the scala vestibuli, the scala tympani being beneath the lamina. 18. The re- maining half turn of the cochlea; the figure is placed in the scala tympani. 19 The lamina spiralis terminating in a falciform extremity. The dark space included within the falciform curve of the extremity of the lamina spiralis is the helicotrema. 20. The infundibulum. * Antonio Scarpa is celebrated for several beautiful surgical and anatomi- cal. monographs; as, for example, his work on ‘‘ Aneurism,’’ ‘‘ De Auditu et Olfactu,’’ &e. An account of the aqua labyrinthi will be found in his anato- mical observations ‘‘ De Structurd Fenestree Rotunde, et de Tympano Secundario.’’ —EEo7oe- ~~ ORGAN OF TASTE. 519 superior ventricle of the vestibule, and are distributed to the sacculus communis and ampullz of the perpendicular and horizontal semicircular canals. The middle vestibular branch sends off numerous filaments, which pass through the openings of the macula cribrosa in the anterior ventricle of the vestibule, and are distributed to the sacculus proprius. The inferior and smallest branch takes its course backwards to the posterior wall of the vestibule, and gives off filaments which pierce the wall-of the ampullary dilatation of the oblique canal to be distributed upon its ampulla. . According to Stiefensand there is in the situation of the point of entrance of the nervous filaments into the ampulle a deep depression upon the exterior of the membrane, and upon the in- terior a corresponding projection, which forms a kind of transverse septum, partially dividing the cavity of the ampulla into two cham- bers. In the substance of the sacculi and ampulla, the nervous filaments radiate in all directions, anastomosing with each other, and forming interlacements and loops, and they terminate upon the inner surface of the membrane in minute papille, resembling those of the retina. The Cochlear nerve divides into numerous filaments which enter the foramina of the tractus spiralis foraminulentus in the base of the cochlea, and passing upwards in the canals of the modiolus, bend out- wards at right angles, to be distributed in the tissue of the lamina spiralis. The central portion of the nerve passes through the tubulus centralis of the modiolus, and supplies the apicial portion of the lamina spiralis. In the lamina spiralis the nervous filaments lying side by side on an eyen plane form numerous anastomosing loops, and spread out into a nervous membrane. According to Treviranus and Gottsche, the ultimate terminations of the filaments assume the form of papille. The Arteries of the labyrinth are derived principally from the auditory branch of the superior cerebellar artery. ORGAN OF TASTE. The Tongue is composed of muscular fibres, which are distributed in layers arranged in various directions: thus, some are disposed longi- tudinally ; others transversely ; others, again, obliquely and_ vertically. Between the muscular fibres is a considerable quantity of adipose substance. The tongue is connected posteriorly with the os hyoides by muscular attachment, and to the epiglottis by mucous membrane, forming the three folds which are called frena epiglottidis. On either side it is held in connection with the lower jaw by mucous membrane, and in front a fold of that membrane is formed beneath its under surface, which is named frenum lingue. The surface of the tongue is covered by a dense layer analogous to the corium of the skin, which gives support to papille. A raphé 520 TONGUE.—PAPILLZ. marks the middle line of the organ, and divides it into symmetrical halves. The Papille of the tongue are the — Papille circumvallate, Papillee conicze, Papillz filiformes, Papillz fungiformes. The Papille circumvallate are of large size, and from fifteen to twenty in number. They are situated on the dorsum of the tongue, near its root, and form a row on each side, which meets its fellow at the middle line, like the two branches of the letter A. Each papilla resembles a cone, attached by its apex to the bottom of a cup- shaped depression: hence they are also named papille calyciformes. This cup-shaped cavity forms a kind of fossa around the papilla, whence their name circumvallate. At the meeting of the two rows of these papillae upon the middle of the root of the tongue, is a deep mucous follicle called foramen cecum. The Papille conice and filiformes cover the whole surface of the tongue in front of the circumvallate, but are most abundant near its apex. They are conical and filiform in shape, and have their points directed backwards. The Papille fungiformes are irregularly dispersed over the dorsum of the tongue, and are easily recognised among the other papille by their rounded heads and larger size. A number of these papille will generally be observed at the tip of the tongue. Behind the papille circumvallate, at the root of the tongue, are a number of mucous glands, which open upon the surface. They have been improperly described as papillee by some authors. Vessels and Nerves. — The tongue is abundantly supplied with blood by the lingual arteries. The Nerves are three in number, and of large size: The gusta- tory branch of the fifth, which is distributed to the papillee, and is the nerve of common sensation and of taste. The glosso-pharyngeal, which is distributed to the mucous membrane, follicles, and glands of the tongue, is a nerve of sensation and motion ; it also serves to associate the tongue with the pharynx and larynx. Panizza’s experiments, tending to prove that this is the true nerve of taste, are rendered questionable by recent observations. The hypoglossal is the motor nerve of the tongue, and is distributed to the muscles. The Mucous membrane which invests the tongue, is continuous with the dermis along the margin of the lips. On either side of the freenum lingue it may be traced through the sublingual ducts into the sublingual glands, and along Wharton’s* ducts into the sub- * Thomas Wharton, an English physician, devoted considerable attention to ORGAN OF TOUCH. 521 maxillary glands: from the sides of the cheeks it passes through the openings of Stenon’s* ducts to the parotid glands: in the fauces, it forms the assemblage of follicles called tonsils, and may be thence traced downwards into the larynx and pharynx, where it is continuous with the general gastro-pulmonary mucous membrane. Beneath the mucous membrane of the mouth are a number of small glandular granules, which pour their secretion upon the surface. A considerable number of them are situated within the lips, in the palate, and in the floor of the mouth. They are named from the position which they may chance to occupy, /abial, palatine glands, &c. ORGAN OF TOUCH. The Skin is the exterior investment of the body, which it serves to cover and protect. It is continuous at the apertures of the internal cavities with the lining membrane of those cavities, the internal skin or mucous membrane, and is composed essentially of two layers, dermis and epidermis. The DERMIS or cutis is chiefly composed of areolar tissue, besides which it has entering into its structure elastic and contractile fibrous tissue, together with blood-vessels, lymphatic vessels and nerves. The areolar tissue exists in greatest abundance in the deeper stratum of the dermis, which is consequently dense, white, and coarse ; the superficial stratum, on the other hand, is fine in texture, reddish in colour, soft, raised into minute papille, and highly vascular and sensi- tive. These differences in structure have given rise to a division of the dermis into the deep stratum, or coriwm, and the superficial, or papillary layer. In the Coriwm the areolar tissue is collected into fasciculi, which are small, and closely interwoven in the superficial strata, large and coarse in the deep strata ; in the latter forming an areolar network with large areole, which are occupied by adipose tissue. These areolz are the channels by which the branches of vessels and nerves find a safe passage to the papillary layer, in which and in the superficial strata of the corium they are principally distributed. The yellow elastic tissue is found chiefly in the superficial strata, the red con- tractile tissue in the deep. It is to the latter that the nipples and scrotum owe their contractile powers, and the general surface of the skin the contraction which is known by the name of cutis anserina. The corium presents some variety in thickness in different parts of the body. Thus in the more exposed regions, as the back, the outer sides of the limbs, the palms and the soles, it is remarkable for its thickness ; while on protected parts it is comparatively thin. On the the anatomy of the various glands: his work, intitled “‘ Adenographia,” &c. was published in 1656. * Nicholas Stenon, a Danish anatomist: he was made professor in Copen- hagen in sie 522 STRUCTURE OF THE DERMIS. eyelids, the penis, and the scrotum it is peculiarly delicate. It is connected by its under surface with the common superficial fascia of the body. The Papillary layer of the dermis is raised in the form of conical prominences or papilla. Upon the general surface of the body the papillz are short and exceedingly minute ; but in other situations, as on the palmar surface of the hands and fingers, and on the plantar surface of the feet and toes, they are long and of large size. They also differ in arrangement; for on the general surface they are distri- buted at equal distances and with- out order ; whereas on the palms and soles, and on the corresponding surfaces of the fingers and toes, they are collected into little square clumps containing from ten to twen- ty papille ; and these little clumps are disposed in parallel rows. It is this arrangement in rows that gives rise to the characteristic pa- rallel ridges and furrows which are met with on the hands: and feet. The papillz in these little square clumps are for the most part uniform in size and length, but every here and there one papilla may be observed which is longer than the rest. The largest papillee of the dermis are those which produce the nail; in the dermic follicle of the nail they are long and filiform, while beneath its concave surface they form longitudinal and parallel plications which extend for nearly the entire length of that organ. In structure each papilla is composed of a more or less convoluted capil- lary and a more or less convoluted nervous loop. ; The EpipErmis or cuticle (scarf-skin) is a product of the dermis, Fig. 159.* ype NU Pees oS * Anatomy of a portion of skin taken from the palm of the hand. 1, 1. The papillary layer, in which the longitudinal furrows (2) marking the arnee ment of the papillee into ridges is shown. Each ridge is moreover divided by transverse furrows (3) into small quadrangular clumps. The quadrangular clumps consist of a tuft of minute conical papille, of which one or two are frequently longer and larger than the rest. In this figure the long papille are alone seen, the rest being too numerous to introduce into a wood-engraving. 4, The rete mucosum raised from the papillary layer and turned back; the under surface of this stratum presents an accurate impression of the Payer Z layer; on which are seen longitudinal ridges corresponding with the longi- tudinal furrows, transverse ridges corresponding with the transverse furrows, and quadrangular depressions corresponding with the quadrangular clumps of papille. Moreover, wherever one of the long papillze exists, a distinct conical sheath will be found in the rete mucosum. 5, 5. Perspiratory ducts drawn out straight by the separation of the rete mucosum from the papillary layer ; the point at which ou perspiratory duct issues from the papillary layer, and pierces the rete mucosum, is the middle of the transverse furrow between the quadrangular masses. eae ee eee STRUCTURE OF THE EPIDERMIS. 523 which it serves to envelope and defend. That surface of the epider- mis which is exposed to the influence of the atmosphere and exterior sources of injury is hard and horny in texture, while that which lies in contact with the papillary layer is soft and cellular. Hence the epidermis, like the dermis, is divisible into two layers, external and internal, the latter being termed the rete mucosum. Moreover, the epidermis is laminated in structure, and the laminz present a progres- sively increasing tenuity and density as they advance from the inner to the outer surface. This difference of density is dependent on the mode of growth of the epidermis, for as the external surface is con- stantly subjected to destruction from attrition and chemical action, so the membrane is continually reproduced on its internal surface, new layers being successively formed on the dermis to take the place of the old. The mode of growth of the epidermis may be thus briefly explained ; a stratum of plastic lymph (liquor sanguinis) is poured out upon the surface of the dermis. This fluid, by virtue of the vital force inherent in itself, and communicated to it by contact with a living tissue, is con- verted into granules, which are termed cell-germs or cyto-blasts. By endosmosis, these cyto-blasts imbibe serum from the lymph and adja- cent tissues, and the outermost layer or pellicle of the cyto-blast be- comes gradually distended by the imbibed fluid. The cyto-blast has now become a cell, and the solid portion of the cyto-blast, which always remains adherent to some one point of the internal surface of the cell- membrane, is the nucleus of the cell. Moreover, within the nucleus one or several nuclei are formed which are termed nucleoli. By a Fig. 160.* continuance of the process of imbi- bition, the cell becomes more or less ‘ spherical ; so that, at this period, ‘> every part of the surface of the pa- F pillary layer of the dermis is coated by a thin and membranous stratum, : (3) consisting of spherical cells lying ’@® Kp) closely pressed together, and corre- sponding with every irregularity -) which the papille present. But, as x this production of cells is a function fe constantly in operation, a new lay- er is formed before the first is com- pleted, and the latter is separated by subsequent formations farther and farther from the surface of the * A diagram illustrative of the development of the epidermis, and of epithelia in general. 1. A granule or cyto-blast. 2. The cell seen rising on the cyto- blast; the latter is now a nucleus and anucleolus may be detected in its interior. 3. The spheroidal cell. 4. The oval cell. 5. The elliptical cell. 6. The flat- tened cell; which, by contact of its walls, is speedily converted into a scale in which the nucleus is lost. 7, A nucleated scale as seen upon its flat surface. 8. Acluster of such scales, 524 STRUCTURE OF. THE EPIDERMIS. ‘papillary layer. With loss of contact with the dermis, the vital force is progressively diminished ; the cell becomes subject to the influence of physical laws, and evaporation of its fluid slowly ensues. In con- sequence of this evaporation the cell becomes collapsed and flattened, and assumes an elliptical form ; the latter is by degrees converted into the flat cell with parallel and contiguous layers, and an included nu- cleolated nucleus; and lastly,the flattened cell desiccates into a thin membranous scale, in which the nucleus is no longer apparent, and is thrown off by desquammation. - From this explanation it is apparent that the epidermis must be composed of a series of strata of nucleolo-nucleated cells, which exhibit a progressive increase of flattening, from the plastic fluid and cyto- blasts of the deepest layer to the thin and horny scales of the outer- most jayers. It is this peculiarity that enables us to split the epider- mis into laminz, the deepest of these laminze, composed of the soft and newly formed cyto-blasts and cells, being the rete mucosum. In the deepest layer, the cyto-blasts are connected with each other by the unemployed portion of plastic lymph which constitutes an intercellu- lar substance ; the cells are connected by their parietes, and the flat- tened cells and scales by their surfaces and borders. The under surface of the epidermis is accurately modelled on the papillary layer of the dermis, each papilla having its appropriate sheath in the newly-formed epidermis or rete mucosum, and each irregularity of surface of the former having its representative in the soft tissue of the latter. On the external surface, this character is lost; the minute elevations corresponding with the papillz, are, as it were, polished down, and the surface is rendered smooth and uniform. The palmar and plantar surfaces of the hands and feet are, however, an ex- ception to this rule; for here, in consequence of the large size of the papille and their peculiar arrangement in rows, ridges corresponding with the papillz are strongly marked on the superficial surface of the epidermis. The epidermis is remarkable for its thickness in situations where the papilla are large, as in the palms and soles. In other situations, it assumes a character which is also due to the nature of the surface of the dermis ; namely, that of being marked by a network of linear furrows, which trace out the surface into small polygonal and lozenge-shaped areze. These lines correspond with the folds of the dermis produced by its movements, and are most numerous where those movements are the greatest, as in the plexuses and on the con- vexities of joints. The dark colour of the skin among the natives of the South is due to the presence of granules of pigment, which are disseminated in the interstices of the cyto-blasts and cells of the rete mucosum, or deve- loped in the same situation into proper pigment cells. In the super- ficial layers of the epidermis, as evaporation proceeds, the colour of the pigment is gradually lost. The pores of the epidermis are the openings of the perspiratory ducts, hair follicles, and sebaceous follicles. APPENDAGES OF THE SKIN. 525 Vessels and Nerves.—The Arteries of the dermis which enter its structure through the areolz of the under surface of the corium, divide into innumerable intermediate vessels, which form a rich capillary plexus in the superficial strata of the skin and in its papillary layer. In the papille of some parts of the dermis, as in the longitudinal pli- cations beneath the nail, the capillary vessels form simple loops, but in other papilla they are convoluted to a greater or less degree in pro- portion to the size and importance of the papille. The Lymphatic vessels probably form, in the superficial strata of the dermis, a plexus, the meshes of which are interwoven with those of the capillary and nervous plexus. No lymphatics have as yet been discovered in the papillee. The Nerves of the dermis, after entering the areole of the deeper part of the corium, divide into minute fasciculi, and these quickly sepa- rate into primitive fibres, which form loops in the papille. In the less sensitive parts of the skin the loops are simple, and more or less acute in their bend, in conformity with the figure of the papilla. In the sen- sitive parts, however, and especially in the tactile papille of the pulps of the fingers, the loop is convoluted to a greater or less extent, and acts as a multiplier of sensation. APPENDAGES OF THE SKIN. The appendages of the skin are the nails, hairs, sebaceous glands, and perspiratory glands and ducts. The Nauzs are horny appendages of the skin, identical in formation with the epidermis, of which they are a part. A nail is convex on its external surface, concave within, and implanted by means of a thin margin or root in a fold of the dermis (matrix), which is nearly two lines in depth, and acts the part of a follicle to the nail. At the bottom of the groove of the follicle are a number of filiform papillz, which produce the margin of the root, and, by the successive formation of new cells, push the nail onwards in its growth. The concave sur- face of the nail is in contact with the dermis, and the latter is covered by papilla, which perform the double office of retaining the nail in its place, and giving it increased thickness by the addition of newly- formed cells to its under surface. It is this constant change occurring in the under surface of the nail, co-operating with the continual re-pro- duction taking place along the margin of the root, which ensures the growth of the nail in the proper direction. The nail derives a peculi- arity of appearance from the disposition and form of the papillee on the ungueal surface of the defmis. Thus, beneath the root, and for a short distance onwards towards its middle, the dermis is covered by papilla which are more minute, and consequently less vascular than the papillae somewhat farther on. This patch of papille is bounded by a semilunar line, and that part of the nail covering it being lighter in co- lour than the rest, has been termed Junula. Beyond the lunula the papillze are raised into longitudinal plaits, which are exceedingly vascu- 526 STRUCTURE OF HAIRS. lar, and give a deeper tint of redness to the nail. These plait-like papillze of the dermis are well calculated by their form to offer an ex- tensive surface both for the adhesion and formation of the nail. The cyto-blasts and cells are developed on every part of their surface, both in the grooves between the plaits and on their sides, anda lamina of nail is formed between each pair of plaits. When the under sur- face of a nail is examined, these longitudinal laminz, corresponding with the longitudinal papillz of the ungueal portion of the dermis, are distinctly apparent, and if the nail be forcibly detached, the lamine may be seen in the act of parting from the grooves of the papilla. It is this structure that gives rise to the ribbed appearance of the nail. The papillary surface of the dermis which produces the nail is conti- nuous around the circumference of the attached part of that organ with the dermis of the surrounding skin, and the horny structure of the nail is consequently continuous with that of the epidermis. Harrs are horny appendages of the skin produced by the involution and subsequent evolution of the epidermis; the involution constituting the follicle in which the hair is enclosed, and the evolution the shaft of the hair. Hairs vary much in size and length in different parts of the body ; in some they are so short as not to appear beyond the follicle ; in others they grow to a great length, as on the scalp ; while along the margins of the eyelids and in the whiskers and beard, they are re- markable for their thickness. Hairs are generally more or less flatten- ed in form, and when the extremity of a transverse section is examined, it is found to possess an elliptical or reniform outline. This examina- tion also demonstrates that the centre of the hair is porous and loose in texture, while its circumference is dense ; thus affording some ground for.a division into a cortical and a medullary portion. The free extre- mity of a hair is generally pointed, and sometimes split into two or three filaments. Its attached extremity is implanted deeply in the in- tegument extending through the dermis into the sub-cutaneous areolar tissue, where it is surrounded by adipose cells. The central extremity of a hair is larger than its shaft, and is called the root 6r bulb. It is usually infundibular in form in the larger hairs, and conical in the smaller hairs, and those of the head. At the bottom of each hair-follicle is a vascular and sensitive for- mative substance or pulp, which is analogous to a papilla of the dermis, and is the producing organ of the hair. The process of formation of a hair by its pulp is identical with that of the formation of the epider- mis by the papillary layer of the dermis. A stratum of plastic lymph is in the first instance exuded by the capillary plexus of the pulp, the lymph undergoes conversion, first into cyto-blasts, then into cells, and the latter are either lengthened out or split into fibres. The cells which are destined to form the surface of the hair undergo a different process. They are converted into flat scales, which enclose the fibrous structure of the interior. These scales, as they are successively pro- duced, overlap those which precede and give rise to the prominent and waving lines which may be seen around the circumference of a hair. SEBACEOUS GLANDS. 527 Fig. 161.* Ta us zs ) a = am C a K€ o, It is this overlapping line that is the cause of the roughness which we experience in drawing a hair from its point to its bulb between the fingers. The bulb is the newly formed portion of the hair: it corre- sponds in figure with that of the pulp, and its expanded form is due to the greater bulk of the fresh cells as compared with the fibres and scales into which they are subsequently converted in the shaft of the The colour of the hair, like that of the epidermis, is due to the pre- sence of granules of pigment contained within and among the cells. The SEBACEOUS GLANDS are sacculated glandular organs embedded in the substance of the dermis, and presenting every variety of com- plexity, from the simplest pouch-like follicle to the sacculated and lo- * The anatomy of the skin. 1. The epidermis, showing the oblique laminz of which it is composed, and the imbricated disposition of the ridges upon its surface. 2. The rete mucosum or deep layer of the epidermis. 3. Two of the quadrilateral papillary clumps, such as are seen in the palm of the hand or sole of the foot; they are composed of minute conical papille. 4. The deep layer of the cutis, the corium. 5. Adipose cells. 6. A sudoriparous gland with its spiral duct, such as is seen in the palm of the hand or sole of the foot 7. Another sudoriparous gland with a straighter duct, such as is seen in the scalp. 8. Two hairs from the scalp, enclosed in their follicles; their relative depth in the skin is preserved. 9. A pair of sebaceous glands, opening by short ducts into the follicle of the hair. 528 SUDORIPAROUS GLANDS. ‘bulated gland. In some situations, the excretory ducts of these glands open independently on the surface of the epidermis; while in others, and the most numerous, they terminate in the follicles of the hairs. The sebaceous glands associated with the hairs are racemiform and lobulat- ed in structure, consisting of sacculi which open by short pedunculated tubuli into a common excretory duct, and the latter, after a short course, terminates in the hair-follicle. In the scalp there are two of these glands to, each hair-follicle. On the nose and face the glands are of large size, distinctly lobulated, and constantly associated with small hair-follicles. In the meatus auditorius the sebaceous (ceruminous) glands are also large and lobulated, but the largest are those of the eyelids, the Meibomian glands. The excretory ducts of sebaceous glands offer some diversity in different parts of the body: thus i in many situations they are short and straight, while in others, as in the palms of the hands and soles of the feet, where the epidermis is thick, they assume a spiral arrangement. The sebaceous ducts and glands are lined by an inversion of the epidermis, which forms a thick and funnel- shaped cone at its commencement, but soon becomes uniform and soft. Sebaceous glands are met with in all parts of the body, but are most abundant in the skin of the face, and in those situations which are naturally exposed to the influence of friction. The sebaceous substance when it collects in inordinate quantities within the excretory ducts becomes the habitat of a very remarkable parasitic animal, the entozoon folliculorum. The SupoRIPAROUS GLANDS are situated deeply in the integument, namely, in the subcutaneous areolar tissue, where they are surround- ed by adipose cells, They are small, oblong bodies, composed of one or more convoluted tubuli, or of a congeries of globular sacs, which open into a common efferent duct. The latter ascends from the gland through the dermis and epidermis, and terminates on the surface by a funnel-shaped and oblique aperture or pore. The efferent duct pre- sents some variety in its course upwards: thus, below the dermis it is curved and serpentine, and having pierced the dermis, if the epidermis be thin, it proceeds more or less directly to the excreting pore. Some- times it is spirally curved beneath the dermis, and having passed’ the latter, is regularly and beautifully spiral in its passage through the epi- dermis, the last turn forming an oblique and valvular opening on the surface. ‘The spiral course of the duct is especially remarkable in the thick epidermis of the palm of the hand and sole of the foot. On those parts of the skin where the papille are irregularly distributed, the efferent ducts of the sudoriparous glands open on the surface also irregularly, while on the palmar and plantar surfaces of the hands and feet, the pores are situated at regular distances along the ridges, at points corresponding with the intervals of the small, square-shaped clumps of papillae. Indeed the apertures of the pores, seen upon the surface of the epidermic ridges, give rise to the appearance of small transverse furrows, which intersect the ridges from point to point. The efferent duct and the component sacs and tubuli of the sudori- ee SUDORIFEROUS DUCTS. 529 parous gland are lined by an inflection of the epidermis. This inflec- tion is thick and infundibiliform in the upper stratum of the dermis, but soon becomes uniform and soft. The infundibiliform projection is drawn out from the duct when the epidermis is removed, and may be perceived on the under surface of the latteras a nipple-shaped cone. A good view of the sudoriferous ducts is obtained by gently separating the epidermis of a portion of decomposing skin; or they may be better seen by scalding a piece of skin, and then withdrawing the epider- mis from the dermis. In both cases it is the lining sheath of epidermis which is drawn out from the duct. bo im. 530 CHAPTER X. OF THE VISCERA. THAT part of the science of anatomy which treats of the viscera is named splanchnology, from the Greek words cradyzvov, viscus, and aédyos. The viscera of the human body are situated in the three great internal cavities: cranio-spinal, thorax, and abdomen. The viscera of the cranio-spinal cavity, namely, the brain and spinal cord, with the principal organs of sense, have been already described, in conjunction with the nervous system. The viscera of the chest are: the central organ of circulation, the heart ; the organs of respiration, the lungs ; and the thymus gland. The abdominal viscera admit of a subdivision into those which properly belong to that cavity, viz. the alimentary canal, liver, pancreas, spleen, kidneys, and supra-renal capsules, and those of the pelvis: the bladder and internal organs of generation. THORAX. The thorax is the conical cavity, situated at the upper part of the trunk of the body; it is narrow above and broad below, and is bounded by the sternum, six superior costal cartilages, ribs, and inter- costal muscles in front; laterally, by the ribs and intercostal muscles ; and, behind, by the same structures, and by the vertebral column, as low down as the upper border of the last rib and the first lumbar vertebra ; superiorly, by the thoracic fascia and first ribs ; and inferi- orly, by the diaphragm. This cavity is much deeper on the posterior than on.the anterior wall, in consequence of the obliquity of the dia- phragm, and contains the heart enclosed in its pericardium, with the great vessels ; the lungs, with their serous coverings, the pleure ; the cesophagus ; some important nerves ; and, in the fetus, the thymus gland. THE HEART. The central organ of circulation, the heart, is situated between the two layers of pleura which constitute the mediastinum, and is enclosed in a proper membrane, the pericardium. Pericardium.—The pericardium is a fibro-serous membrane like the dura mater, and resembles that membrane in deriving its serous layer from the reflected serous membrane of the viscus which it encloses. PERICARDIUM.—HEART. 531 It consists, therefore, of two layers, an external fibrous and an in- ternal serous. The fibrous layer is attached, above, to the great vessels at the root of the heart, where it is continuous with the tho- racic fascia ; and below, to the tendinous portion of the diaphragm. The serous membrane invests the heart with the commencement of its great vessels, and is then reflected upon the internal surface of the fibrous layer. The Hxart is placed obliquely in the chest, the base being directed upwards and backwards towards the right shoulder; the apex forwards and to the left, pointing to the space between the fifth and sixth ribs, at about two or three inches from the sternum, Its under side is flat- tened, and rests upon the tendinous portion of the diaphragm ; its upper side is rounded and convex, and formed principally by the right ventricle, and partly by the left. Surmounting the ventricles are the corresponding auricles, whose auricular appendages are directed for- wards, and slightly overlap the root of the pulmonary artery. The pulmonary artery is the large anterior vessel at the root of the heart ; it crosses obliquely the commencement of the aorta. The heart con- sists of two auricles and two ventricles, which are respectively named, from their position, right and left. The right is the venous side of the heart ; it receives into its auricle the venous blood from every part of the body, by the superior and inferior cava and coronary vein. From the auricle the blood passes into the yentricle, and from the ventricle through the pulmonary artery, to the capillaries of the lungs. From these it is returned as arterial blood to the left auricle ; from the left auricle it passes into the left ventricle ; and from the left ven- tricle is carried through the aorta, to be distributed to every part of the body, and again returned to the heart by the veins. This consti- tutes the course of the adult circulation. The heart is best studied in situ. If, however, it be removed from the body, it should be placed in the position indicated in the above description of its situation. A transverse incision should then be made along the ventricular margin of the right auricle, from the ap- pendix to its right border, and crossed by a perpendicular incision, carried from the side of the superior to the inferior cava. The blood must then be removed. Some fine specimens of white fibrin are fre- quently found with the coagula ; occasionally they are yellow and gelatinous. This appearance deceived the older anatomists, who called these substances “ polypus of the heart:” they are also fre- quently found in the right ventricle, and sometimes in the left cavities. The Ricur Avricxe is larger than the left, and is divided into a principal cavity or sinus, and an appendix auricule. The interior of the sinus presents for examination five openings ; two valves ; two relicts of foetal structure ; and two peculiarities in the proper structure of the auricle, They may be thus arranged :— 532 - RIGHT AURICLE. Superior cava, Inferior cava, Openings . . . .. Coronary vein, Foramina Thebesii, Auriculo-ventricular opening. Fig. 162.* A\\ * The anatomy of the heart. 1. The right auricle. 2. The entrance of the superior vena cava. 3. The entrance of the inferior cava, 4. The opening of the coronary vein, half closed by the coronary valve. 5. The Eustachian valve. 6. The fossa ovalis, surrounded by the annulus ovalis. 7, The tuber- culum Loweri. 8. The musculi pectinati in the appendix auricule. 9. The auriculo-ventricular opening. 10. The cavity of the right ventricle. 11. The tricuspid valve, attached by the chordee tendineze to the carnez columne (12). 13. The pulmonary artery, guarded at its commencement by three semilunar valves. 14. The right pulmonary artery, passing beneath the arch and be- hind the ascending aorta. 15. The left pulmonary artery, crossing in front of the descending aorta. * The remains of the ductus arteriosus, acting as a ligament between the pulmonary artery and arch of the aorta. The arrows mark the course of the venous blood through the right side of the heart. Entering the auricle by the superior and inferior cave, it passes through the auriculo-ventricular opening into the ventricle, and thence through the pul- monary artery to the lungs. 16. The left auricle. 17. The openings of the four pulmonary veins. 18. The auriculo-ventricular opening. 19. The left ventricle. 20, The mitral valve, attached by its chordee tendinex to two large column carne, which project from the walls of the ventricle. 21. The commencement and course of the ascending aorta behind the pulmonary artery, marked by an arrow. The entrance of the vessel is guarded by three semilunar valves. 22. The arch of the aorta. The comparative thickness of the two ventricles is shown in the diagram. The course of the pure blood through the left side of the heart is marked by arrows. The blood is brought from the lungs by the four pulmonary veins into the left auricle, and passes through the auriculo-ventricular opening into the left ventricle, whence it is conveyed by the aorta to every part of the body. ‘RIGHT AURICLE. 533 ie i § Eustachian valve Vee og Vales t Coronary valve. ‘ ‘ Annulus ovalis, Relicts of fetal structure . ; Dakex ovalia. ; Tuberculum Loweri, Structure of the auricle . ; Musculi pectinati. The Superior cava returns the blood from the upper half of the body, and opens into the upper and front part of the auricle. The Inferior cava returns the blood from the lower half of the body, and opens through the lower and posterior wall, close to the partition between the auricles (septum auricularum), The direction of these two vessels is such, that a stream forced through the superior cava would be directed towards the auriculo-ventricular opening. In like manner, a stream rushing upwards by the inferior cava would force its current against the septum auricularum ; this is the proper direction of the two currents during feetal life. The Coronary vein returns the venous blood from the substance of the heart ; it opens into the auricle between the inferior cava and the auriculo-ventricular opening, under cover of the coronary valve. The Foramina Thebesii* are minute pore-like openings, by which the venous blood exudes directly from the muscular structure of the . heart into the auricle, without entering the venous current. These openings are also found in the left auricle, and in the right and left ventricles. The Awriculo-ventricular opening is the large opening of communica- tion between the auricle and ventricle. The Eustachian*+ valve is a part of the apparatus of foetal circulation, and serves to direct the placental blood from the inferior cava, through the foramen ovale into the left auricle. In the adult it is a mere vestige and imperfect, though sometimes it remains of large size. It is formed by a fold of the lining membrane of the auricle, containing some muscular fibres, is situated between the opening of the inferior cava and the auriculo-ventricular opening, and is generally connected with the coronary valve. The Coronary valve is a semilunar fold of the lining membrane, stretching across the mouth of the coronary vein, and preventing the reflux of the blood in the vein during the contraction of the auricle. The Annulus ovalis is situated on the septum auricularum, opposite the termination. of the inferior cava. It is the rounded margin of the septum, which occupies the place of the foramen ovale of the feetus. * Adam Christian Thebesius. His discovery of the openings now known by his name is contained in his “‘ Dissertatio Medica de Circulo Sanguinis in Corde,’’ 1708. + Bartholomew Eustachius, born at San Severino, in Naples, was Professor of Medicine in Rome, where he died in 1570. He was one of the founders of modern anatomy, and the first who illustrated his works with good engravings on copper. 534 RIGHT VENTRICLE. The Fossa ovalis is an oval depression corresponding with the foramen ovale in the foetus, This opening is closed at birth by a thin valvular layer, which is continuous with the left margin of the an- nulus and is frequently imperfect at its upper part. The depression or fossa in the right auricle results from this arrangement. ‘There is no fossa ovalis in the left auricle. The Tuberculum Loweri* is the portion of auricle intervening be- tween the openings of the superior and inferior cava. Being thicker than the walls of the veins it forms a projection, which was supposed by Lower to direct the blood from the superior cava into the auriculo- ventricular opening. The Musculi pectinati are small muscular columns situated in the appendix auricule. They are numerous, and are arranged parallel with each other ; hence their cognomen, “ pectinati,” like the teeth of a comb. The RIGHT VENTRICLE is triangular and prismoid in form. Its an- terior side is convex, and forms the larger proportion of the front of the heart. The posterior side, which is also inferior, is flat, and rests upon the diaphragm ; the inner side corresponds with the partition between the two ventricles, septum ventriculorum. The right ventricle is to be laid open by making an incision parallel with, and a little to the right of, the middle line, from the pulmonary artery in front, to the apex of the heart, and thence by the side of the middle line behind to the auriculo-ventricular opening. It contains, to be examined, two openings, the auriculo-ventricular and that of the pulmonary artery ; two apparatus of valves, the tri- cuspid and semilunar ; and a muscular and tendinous apparatus be- longing to the tricuspid valves. They may be thus arranged :— Auriculo-ventricular opening, Opening of the pulmonary artery. Tricuspid valves, Semilunar valves. Chorde tendinez, Carne columnz. The Auriculo-ventricular opening is surrounded by a fibrous ring, covered by the lining membrane of the heart. It is the opening of communication between the right auricle and ventricle. The Opening of the pulmonary artery is situated close to the septum ventriculorum, on the left side of the right ventricle, and upon the anterior aspect of the heart. The Tricuspid valves are three triangular folds of the lining mem- * Richard Lower, M.D. ‘“‘ Tractatus de Corde; item de Motu et Colore Sanguinis,’’ 1669. His dissections were made upon quadrupeds, and his ob- servations relate rather to animals than to man. COLUMNZ CARNE. 535 brane, strengthened by a thin layer of fibrous tissue. They are con- nected by their base around the auriculo-ventricular opening ; and by their sides and apices, which are thickened, they give attachment to a number of slender tendinous cords, called chord tendines. The chorde@ tendinee are the tendons of the thick muscular columns (co- lumne carnee) which stand out from the walls of the ventricle, and serve as muscles to the valves. A number of these tendinous cords converge to a single muscular attachment. The tricuspid valves pre- vent the regurgitation of blood into the auricle during the contraction of the ventricle, and they are prevented from being themselves driven back by the chord tendinez and their muscular attachments. This connection of the muscular columns of the heart to the valves has caused their division into active and passive. The active valves are the tricuspid and mitral ; the passive, the semilunar and coronary. Mr. King, of Guy’s Hospital, has made the tricuspid valves the subject of careful investigation, and has recorded his observations in the Guy’s Hospital Reports.* The valves consist, according to Mr. King, of ewrtains, cords, and columns, The anterior valve or curtain is the largest, and is so placed as to prevent the filling of the pulmonary artery during the distension of the ventricle. The right valve or curtain is of smaller size, and is situated upon the right side of the auriculo-ventricular opening. The third valve, or “ fixed curtain,” is connected by its cords to the septum ventriculorum. The cords (chord tendinez.) of the anterior curtain are attached, principally, to a long column (columna carnea), which is connected with the “ right or thin and yielding wall of the ventricle.” From the lower part of this column a transverse muscular band, the “ long moderator band,” is stretched to the septum ventriculorum or “ solid wall”? of the ventricle. The right curtain is connected, by means of its cords, partly with the long column, and partly with its own proper column, the second column, which is also attached to the “ yielding wall” of the ven- tricle. A third and smaller column is generally connected with the right curtain. The “ fiwed curtain” is named from its attachment to the “ solid wall” of the ventricle, by means of cords only, without fleshy columns. From this arrangement of the valves it follows, that if the right ventricle be over-distended, the thin or “ yielding wall” will give way, and carry with it the columns of the anterior and right valves. The cords connected with these columns will draw down the edges of the corresponding valves, and produce an opening between the curtains, through which the superabundant blood may escape into the auricle, and the ventricle be relieved from over-pressure. This beautiful mechanism is therefore adapted to fulfil the “ function of a safely valve.” The Columne carnee (fleshy columns) is a name expressive of the appearance of the internal walls of the ventricles, which seem formed * << Essay on the Safety Valve Function in the Right Ventricle of the Human Heart,” by T. W. King. Guy’s Hospital Reports, vol. ii. 536 . LEFT AURICLE. of muscular columns interlacing in almost every direction. They are divided into three sets, according to the manner of their connection. 1. The greater number are attached by the whole of one side, and merely form convexities into the cavity of the ventricle. 2. Others are connected by both extremities, being free in the middle. 3. A few (columnz papillares) are attached by one extremity to the walls of the heart, and by the other give insertion to the chordz tendinez. The Semilunar valves, three in number, are situated around the commencement of the pulmonary artery, being formed by a folding of its lining membrane, strengthened by a thin layer of fibrous tissue. They are attached by their convex borders, and free by the concave which are directed upwards in the course of the vessel, so that, during the current of the blood along the artery they are pressed against the sides of the cylinder; but if any attempt at regurgitation ensue they are immediately expanded, and effectually close the entrance of the tube. The margins of the valves are thicker than the rest of their extent, and each valve presents in the centre of this margin a small fibro-cartilaginous tubercle, called corpus Arantii,* which locks in with the two others during the closure of the valves, and secures the triangular space that would otherwise be left by the approximation of three semilunar folds, Between the semilunar valves and the cylinder of the artery are three pouches, called the pulmonary sinuses (sinuses of Valsalva). Similar sinuses are situated behind the valves at the commencement of the aorta, and are larger and more capacious than those of the pulmo- nary artery. The Pulmonary artery commences by a scalloped border, corre - sponding with the three valves which are attached along its edge. It is connected to the ventricle by muscular fibres, and by the lining mem- brane of the heart. The Lerr AvuRIcLE is somewhat smaller, but thicker, than the right ; of a cuboid form, and situated more posteriorly. The appendix auriculé is constricted at its junction with the auricle, and has a fo- liated appearance ; it is directed forwards towards the root of the pulmonary artery, to which the auricule of both sides appear to converge. The left auricle is to be laid open by a + shaped incision, the hori- zontal section being made along the border which is attached to the base of the ventricle. It presents for examination five openings, and the muscular structure of the appendix ; these are,— Four pulmonary veins, Auriculo-ventricular opening, Musculi pectinati. _* Julius Ceesar Arantius, Professor of Medicine in Bologna. He was a dis- ciple of Vesalius, one of the founders of modern anatomy. His treatise ‘‘ De Humano Feetu’’ was published at Kome, in 1564, LEFT VENTRICLE. 537 The Pulmonary veins, two from the right and two from the left lung, open into the corresponding sides of the auricle. The two left pulmonary veins terminate frequently by a common opening. The Auriculo-ventricular opening is the aperture of communication between the auricle and ventricle. The Musculi pectinati are fewer in number than in the right auricle, and are situated only in the appendix auricule. Lerr VENTRICLE.—The left ventricle is to be opened by making an incision a little to the left of the septum ventriculorum, and con- tinuing it around the apex of the heart to the auriculo-ventricular opening behind. The left ventricle is conical, both in external figure and in the form of its internal cavity. It forms the apex of the heart, by projecting beyond the right ventricle, while the latter has the advantage in length towards the base. Its walls are about seven lines in thick- ness, those of the right ventricle being about two lines and a half. It presents for examination, in its interior, two openings, two valves, and the tendinous cords and muscular columns ; they may be thus arranged :— Auriculo-ventricular opening, Aortic opening. Mitral valves, Semilunar valves. Chordz tendinez, Columnz carnez. The Auriculo-ventricular opening is a dense fibrous ring, covered by the lining membrane of the heart, but smaller in size than that of the right side. The Mitral valves are attached around the auriculo-ventricular opening, as are the tricuspid in the right ventricle. They are thicker than the tricuspid, and consist of only two segments, of which the larger is placed between the auriculo-ventricular opening and the com- mencement of the aorta, and acts the part of a valve to that foramen during the filling of the ventricle. The difference in size of the two valves, both being triangular, and the space between them, has given rise to the idea of a “ dishop’s mitre,” after which they were named. These valves, like the tricuspid, are furnished with an apparatus of tendinous cords, chorde tendinee, which are attached to two very large columne@ carnee. The Columne carnee admit of the same arrangement into three kinds, as on the right side. Those which are free by one extremity, the columnz papillares, are two in number, and larger than those on the opposite side ; one being placed on the left wall of the ventricle, and the other at the junction of the septum ventriculorum with the posterior wall. 538 STRUCTURE OF THE HEART. The Semilunar valves are placed around the commencement of the aorta, like those of the pulmonary artery ; they are similar in struc- ture, and are attached to the scalloped border by which the aorta is connected with the ventricle. The tubercle in the centre of each fold is larger than those in the pulmonary valves, and it was these that Arantius particularly described ; but the term “ corpora Arantii” is now applied indiscriminately to both. The fosse between the semi- lunar valves and the cylinder of the artery are larger than those of the pulmonary artery ; they are called the “ sinus aortict” (sinuses of Valsalva). STRUCTURE OF THE HEART. The arrangement of the fibres of the heart has been made the subject of careful and accurate investigation by Mr. Searle, to whose excellent article, “ Fibres of the Heart,” in the Cyclopedia of Anatomy and Physiology, I am indebted for the following summary of their distribution :— For the sake of clearness of description the fibres of the ventricles have been divided into three layers, superficial, middle, and internal, all of which are disposed in a spiral direction around the cavities of the ventricles: The mode of formation of these three layers will be best understood by adopting the plan pursued by Mr. Searle in tracing the course of the fibres from the centre of the heart towards its periphery. The left surface of the septum ventriculorum is formed by a broad and thick layer of fibres, which proceed backwards in a spiral direction around the posterior aspect of the left ventricle, and become aug- mented on the left side of that ventricle by other fibres derived from the bases of the two columne papillares. The broad and thick band formed by the fibres from these two sources, curves around the apex and lower third of the left ventricle to the anterior border of the septum, where it divides into two bands, a short or apicial band, and a.long or basial band. The Short or apicial band is increased in thickness at this point by receiving a layer of fibres (derived from the root of the aorta and carnez column) upon its internal surface, from the right surface of the septum ventriculorum ; it is then continued onwards in a spiral direction from left to right, around the lower third of the anterior surface, and the middle third of the posterior surface of the right ventricle to the posterior border of the septum. From the latter point the short band is prolonged around the posterior and outer border of the left ventricle to the anterior surface of the base of that ventricle, and is inserted into the anterior border of the left auriculo-ventricular ring, and the anterior part of the root of the aorta and pulmonary artery The Long or basial band, at the anterior border of the septum, passes FIBRES OF THE VENTRICLES. 539 directly backwards through the septum, forming its middle layer, to the posterior ventricular groove, where it becomes joined by fibres derived from the root of the pulmonary artery. It then winds spirally around the middle and upper third of the left ventricle to the anterior border of the septum, where it is connected by means of its internal surface with the superior fibres derived from the aorta, which form part of the right wall of the septum. From this point it is continued around the upper third of the anterior and posterior surface of the right ventricle to the posterior border of the septum, where it is con- nected with the fibres constituting the right surface of the septum ventriculorum. At the latter point the fibres of this band begin to be twisted upon themselves, like the strands of a rope, the direction of the twist being from below upwards. This arrangement of fibres is called by Mr. Searle “the rope ;” it is continued spirally upwards, forming the brim of the left ventricle, to the anterior surface of the base of that ventricle, where the twisting of the fibres ceases. The long band then curves inwards towards the septum, and spreads out upon the left surface of the septum into the broad and thick layer of fibres with which this description commenced. The most inferior of the fibres of the left surface of the septum ventriculerum, after winding spirally around the internal surface of the apex of the left ventricle, so as to close its extremity, form a small fasciculus, which is excluded from the interior of the ventricle, and expands in a radiated manner over the surface of the heart, con- stituting its superficial layer of fibres. The direction of these fibres is, for the most part, oblique, passing from left to right on the anterior, and from right to left on the posterior surface of the heart, becoming more longitudinal near its base, and terminating by being inserted into the fibrous rings of the auriculo-ventricular openings, and of the pul- monary artery and aorta. Over the right ventricle the superficial fibres are increased in number by the addition of accessory fibres from the right surface of the septum, which pierce the middle layer, and take the same direction with the superficial fibres from the apex of the left ventricle, and of other accessory fibres from the surface of both ventricles, From this description it will be perceived, that the superficial layer of fibres is very scanty, and is pretty equally distributed over the surface of both ventricles. The middle layer of both ventricles is formed by the two bands, short and long. But the internal layer of the two ventricles is very differently constituted : that of the left is formed by the spiral expansion of the fibres of the rope, and of the two columne papillares; that of the right remains to be described. The septum ventriculorum also consists of three layers, a left layer, the radiated expansion of the rope and carneze columnz ; a middle layer, the long band ; and a right layer, belonging to the proper wall of the right ventricle, and continuous both in front and behind with the long band, and in front also with the short band, and with the superficial layer of the right ventricle. 540 . FIBRES OF THE AURICLES. The Internal layer of the right ventricle is formed by fasciculi of fibres which arise from the right segment of the root of the aorta, from the entire circumference of the root of the pulmonary artery, and from the bases of the columnz papillares. The fibres from the root of the aorta, associated with some from the carnez columne, constitute a layer which passes obliquely forwards upon the right side of the septum. The superior fibres coming directly from the aorta join the internal surface of the long band at the anterior border of the septum, while the lower two-thirds of the layer are continuous with the in- ternal surface of the short band, some of its fibres piercing that band to augment the number of superficial fibres. The fibres derived from the root of the pulmonary artery, conjoined with those from the base of one of the columne papillares, curve forwards from their origin, and wind obliquely downwards and backwards around the internal surface of the wall of the ventricle to the posterior border of the septum, where they become continuous with the long band, directly that it has passed backwards through the septum. Fibres of the Auricles—The fibres of the auricles are disposed in two layers, external and internal. The internal layer is formed of fasciculi which arise from the fibrous rings of the auriculo-ventricular openings and proceed upwards to enlace with each other, and con- stitute the appendices auricularum. These fasciculi are -parallel in their arrangement, and in the appendices form projections and give rise to the appearance which is denominated musculi pectinati. In their course they give off branches which connect adjoining fasciculi, and form a columnar interlacement between them. External Layer. — The fibres of the right auricle having completed the appendix, wind from left to right around the right border of this auricle, and along its anterior aspect, beneath the appendix, to the anterior surface of the septum. From the septum they are continued to the anterior surface of the left auricle, where they separate into three bands, superior, anterior, and posterior. The superior band proceeds onwards to the appendix, and encircles the apex of the auricle. The anterior band passes to the left, beneath the appendix, and winds as a broad layer completely around the base of the auricle, and through the septum to the root of the aorta, to which it is partly attached, and from this point is continued onwards to the appendix, where its fibres terminate by interlacing with the musculi pectinati. The posterior band crosses the left auricle obliquely to its posterior part, and winds from left to right around its base, encircling the open- ings of the pulmonary veins ; some of its fibres are lost upon the surface of the auricle, others are continued onwards to the base of the aorta ; and a third set, forming a small band, is prolonged along the anterior edge of the appendix to its apex, where it is continuous with the superior band, The septum auricularum has four sets of fibres entering into its formation ; 1. The fibres arising from the auriculo- ventricular rings at each side ; 2. Fibres arising from the root of the aorta, which pass upwards to the transverse band, and to the root of THE LARYNX. 541 the superior cava ; 3. Those fibres of the anterior band that pass through the lower part of the septum in their course around the left auricle ; and, 4. A slender fasciculus, which crosses through the septum from the posterior part of the right auriculo-ventricular ring to the left auricle. It will be remarked from this description, that the left auricle is considerably thicker and more muscular than the right. Vessels and Nerves.—The Arteries supplying the heart are the an- terior and posterior coronary. The Veins accompany the arteries, and empty themselves by the common coronary vein into the right auricle. The (ymphatics terminate in the glands about the root of the heart. The nerves of the heart are derived from the cardiac plexuses, which are formed by communicating filaments from the sympathetic and pheumogastric. ORGANS OF RESPIRATION AND VOICE. ___ The organs of respiration are the two lungs, with their air-tube, the trachea, to the upper part of which is adapted an apparatus of carti- lages, constituting the organ of voice, or larynx. THE LARYNX. The Larynx is situated at the fore part of the neck, between the trachea and the base of the tongue. It is a short tube, having an hour-glass form, and is composed of cartilages, ligaments, muscles, vessels, nerves, and mucous membrane. The Cartilayes are the — Thyroid, Cricoid, Two Arytenoid, Two cuneiform, Epiglottis. The Thyroid (Suests — IN 546 MUSCLES OF THE LARYNX. The Thyro-epiglottideus appears to be formed by the upper fibres of the thyro-arytenoideus muscle: they spread out upon the external surface of the sacculus laryngis and in the aryteno-epiglottidean fold of mucous membrane, in which they are lost; a few of the anterior fibres being continued onwards to the side of the epiglottis. The Aryteno-epiglottideus superior consists of a few scattered fibres, which pass forwards in the fold of mucous membrane forming the lateral boundary of the entrance into the larynx, from the apex of the arytenoid cartilage to the side of the epiglottis. The Aryteno-epiglottideus inferior—This muscle, described by Mr. Hilton, is very important in relation to the sacculus laryngis, with which it is closely connected. It may be found by raising the mucous membrane immediately above the ventricle of the larynx. It arises by a narrow and fibrous origin from the arytenoid cartilage, just above the attachment of the chorda vocalis; and passing forwards, and a little upwards, expands over the upper half, or two-thirds of the sac- culus laryngis, and is inserted by a broad attachment into the side of the epiglottis. Actions.—From a careful investigation of the muscles of the larynx Mr. Bishop* concludes that the crico-arytenoidei postici open the glottis, while all the rest close it. The arytenoideus approximates the arytenoid cartilages posteriorly, and the crico-arytenoidei and thyro- arytenoidei anteriorly ; the latter, moreover, close the glottis mesially. The crico-thyroidei are tensors of the chorde vocales, and these muscles, together with the thyro-arytenoidei regulate the tension, po- sition, and vibrating length of the vocal cords. The crico-thyroid muscles effect the tension of the chordz vocales by rotating the cricoid on the inferior cornua of the thyroid; by this ac- tion the anterior portion is drawn upwards and made to approximate the inferior border of the thyroid, while the posterior and superior border of the cricoid, together with the arytenoid cartilages, is carried backwards. The crico-arytenoidei postici separate the chordze vocales by drawing the arytenoid cartilages outwards and downwards. The crico-arytenoidei laterales, by drawing the outer angles of the aryte- noid cartilages forwards, approximate the anterior angles to which the chordz vocales are attached. The thyro-arytenoidei draw the aryte- noid cartilages forwards, and, by their connection with the chorde vo- cales, act upon the whole length of those cords. The thyro-epiglottideus acts principally by compressing the glands of the sacculus laryngis and the sac itself: by its attachment to the epiglottis it would act feebly upon that valve. The aryteno-epiglot- tideus superior serves to keep the mucous membrane of the sides of the opening of the glottis tense, when the larynx is drawn upwards, and the opening closed by the epiglottis. Of the aryteno-epiglottideus, the “functions appear to be,” writes Mr. Hilton, “to compress the subjacent glands which open into the pouch; to diminish the capacity * Cyclopedia of Anatomy and Physiology. Article, Larynx. MUCOUS MEMBRANE. 547 of that cavity, and change its form; and to approximate the epiglottis and the arytenoid cartilage.” Mucous membrane.—The aperture of the larynx is a triangular, or cordiform opening, broad in front and narrow behind; bounded ante- riorly by the epiglottis, posteriorly by the arytenoideus muscle, and on either side by a fold of mucous membrane stretched between the side of the epiglottis and the apex of the arytenoid cartilage. Onthe mar- gin of this aryteno-epiglottidean fold the cuneiform cartilage forms a prominence more or less distinct. The cavity of the larynx is divided into two parts by an oblong constriction produced by the prominence of the chordz vocales. That portion of the cavity which lies above the constriction is broad and triangular above, and narrow below ; that which is below it is narrow above and broad and cylindrical below, the circumference of the cylinder corresponding with the ring of the cricoid ; while the space included by the constriction is a narrow, tri- angular fissure, the glottis or rima glottidis. The form of the glottis is that of an isosceles triangle, bounded on the sides by the chorde vo- _cales and inner surface of the arytenoid cartilages, and behind by the arytenoideus muscle. Its length is greater in the male than in the fe- male, and in the former measures somewhat less thananinch. Imme- diately above the prominence caused by the chorda vocalis, and ex- tending nearly its entire length on each side of the cavity of the larynx, is an elliptical fossa, the ventricle of the larynx. This fossa is bounded below by the chorda vocalis, which it serves to isolate, and above by a border of mucous membrane folded upon the lower edge of the supe- rior thyro-arytenoid ligament. The whole of the cavity of the larynx with its prominences and depressions, is lined by mucous membrane, which is continuous superiorly with that of the mouth and ph and inferiorly is prolonged through the trachea and bronchial tubes into the air cells of the lungs. In the ventricles of the larynx the mucous membrane forms a cecal pouch of variable size, termed by Mr. Hilton the sacculus laryngis.* The sacculus laryngis is directed * This sac was described by Mr. Hilton before he was aware that it had already been pointed out by the older anatomists. I myself made a dissection, which I still possess, of the same sac in an enlarged state, during the month of August, 1837, without any knowledge either of Mr. Hilton’s labours, or Mor- gagni’s account. The sac projected considerably above the upper border of the thyroid cartilage, and the extremity had been snipped off on one side in the removal of the muscles. The 1 x was presented to me by Dr. George Moore of Camberwell; he had obtained it from a child who died of bronchial dis- ease; and he conceived that this peculiar disposition of the mucous membrane might possibly explain some of the symptoms by which the case was accom- panied. Cruveilhier made the same observation in equal ignorance of Mor- gagni’s description, for we read in a note at page 677, vol. ii. of his Anatomie Descriptive,—< J’ai vu pour la premiére fois cette arriére cavité chez un indi- vidu affecté de phthisie laryngée, ot elle était trés-développée. Je fis des re- cherches sur le larynx d’autres individus, et je trouvai que cette disposition était constante. Je ne savais pas alors que Morgagni avait indiqué et fait repré- senter la méme disposition.’? Cruveilhier compares its form very aptly to a 548 GLANDS OF THE LARYNX.—TRACHEA. upwards, sometimes extending as high as the upper border of the thy- roid cartilage, and occasionally above that border. When dissected from the interior of the larynx it is found covered by the aryteno-epi- glottideus muscle and a fibrous membrane, which latter is attached to the superior thyro-arytenoid ligament below ; to the epiglottis in front ; and to the upper border of the thyroid cartilage above. If examined from the exterior of the larynx, it will be seen to be covered by the thyro- epiglottideus muscle. On the surface of its mucous membrane are the openings of sixty or seventy small follicular glands, which are situated in the sub-mucous tissue, and gives to its external surface a rough and ill-dissected appearance. This mucous secretion is intended for the lubrication of the chordz vocales, and is directed upon them by two small valvular folds of mucous membrane, which are situated at the entrance of the sacculus. Glands.—The bodies known as the glands of the larynx, namely, the epiglottic and the arytenoid are very improperly named. The former is a mass of areolar and adipose tissue, situated in the triangular space between the front surface of the apex of the epiglottis, the hyo-epi- glottidean and the thyro-hyoidean ligament. The latter is the body which forms a prominence in the aryteno-epiglottidean fold of mucous membrane, and has been described among the cartilages as the aryte- noid cartilage. Vessels and Nerves.—The Arteries of the larynx are derived from the superior and inferior thyroid. The nerves are the superior laryn- geal and recurrent laryngeal; both branches of the pneumogastric. The two nerves communicate with each other freely; but the superior laryngeal is distributed principally to the mucous membrane at the en- trance of the larynx; the recurrent, to the muscles. THE TRACHEA. The TracHEa extends from opposite the fifth cervical vertebra to opposite the third dorsal, where it divides into the two bronchi. The right bronchus, larger than the left, passes off nearly at right angles to the upper part of the corresponding lung. The /eft descends obliquely, and passes beneath the arch of the aorta, to reach the left ung. The Trachea is composed of — Fibro-cartilaginous rings, Fibrous membrane, Mucous membrane, Longitudinal elastic fibres, Muscular fibres, Glands. ** Phrygian casque,” and Morgagni’s figure, Advers. 1. Epist. Anat. 3. plate 2. fig. 4. has the same appearance. But neither of these anatomists notice the fol- licular glands described by Mr. Hilton. THYROID GLAND. : 549 The Fibro-cartilaginous rings are from fifteen to twenty in number, and extend for two-thirds around the cylinder of the trachea. They are deficient at the posterior part, where the tube is completed by fibrous membrane. The last ring has usually a triangular form in front. The rings are connected to each other by a membrane of yellow elastic fibrous tissue, which in the space between the extremities of the cartilages, posteriorly, forms a distinct layer. The Longitudinal elastic fibres are situated immediately beneath the mucous membrane on the posterior part of the trachea, and enclose the entire cylinder of the bronchial tubes to their ultimate terminations. The Muscular fibres form a thin layer, extending transversely be- tween the extremities of the cartilages. On the posterior surface they are covered in by a cellulo-fibrous lamella, in which are lodged the tracheal glands. These are small flattened ovoid bodies, situated in great number between the fibrous and muscular layers of the membra- nous portion of the trachea, and also between the two layers of elastic fibrous tissue connecting the rings. They pour their secretion upon the mucous membrane. Thyroid Gland. The thyroid gland or body is one of those organs which it is difficult to classify from the absence of any positive knowledge with regard to its function. It is situated upon the trachea, and in an anatomical arrangement may therefore be considered in this place, although bear- ing no part in the function of respiration. This gland consists of two lobes, which are placed one on each side of the trachea, and are connected with each other by means of an isthmus, which crosses its upper rings. There is considerable variety in the situation and breadth of this isthmus; which should be recollected in the performance of operations upon the trachea. In structure it ap- pears to be composed of a dense cellular parenchyma, enclosing a great number of vessels. The gland is larger in young subjects and in females, than in the adult and males. It is the seat of an enlargement called bronchocele, goitre, or the Derbyshire neck. A muscle is occasionally found connected with its upper border or with its isthmus; and attached, superiorly, to the body of the os hyoides, or to the thyroid cartilage. It was named by Soemmering the “ levator glandule thyroidee ;” fig. 163, p. 543. Vessels and Nerves.—It is abundantly supplied with blood by the superior and inferior thyroid arteries. Sometimes an additional artery is derived from the arteria innominata, and ascends upon the front of the trachea to be distributed to the gland. The wounding of this vessel, in tracheotomy, might be fatal to the patient. The zerves are derived from the superior laryngeal and sympathetic. J 550 THE LUNGS. The lungs are two conical organs, situated one on each side of the chest, embracing the heart, and separated from each other by that organ and by a membranous partition, the mediastinum. On the ex- ternal or thoracic side they are convex, and correspond with the form of the cavity of the chest; internally they are concave, to receive the convexity of the heart. Superiorly they terminate in a tapering cone, which extends above the level of the first rib, and inferiorly they are broad and concave, and rest upon the convex surface of the diaphragm. Fig. 166*. * Anatomy of the heart and lungs. 1. The right ventricle; the vessels ‘to the right of the figure are the middle coronary artery and veins ; and those to its left, the anterior coronary artery and veins. 2. The left ventricle. 3. The right auricle. 4. The left auricle. 5. The pulmonary artery. 6. The right pulmonary artery. 7. The left pulmonary artery. 8. The remains of the duc- tus arteriosus. 9. The arch of the aorta. 10. The superior vena cava. 11. The right arteria innominata, and in front of it the vena innominata. 12. The right subclavian vein, and behind it its corresponding artery. 13. The right common carotid artery and vein. 14. The left vena innominata. 15. The left carotid artery and vein. 16. The left subclavian vein and artery. 17. The trachea. 18. The right bronchus. 19. The left bronchus. 20, 20. The pul- monary veins ; 18, 20, form the root of the right lung; and 7, 19, 20, the root of the left. 21. The superior lobe of the right lung. 22. Its middle lobe. —e inferior lobe. 24. The superior lobe of the left lung. 25. Its inferior STRUCTURE OF THE LUNGS. 551 Their posterior border is rounded and broad, the anterior sharp, and. marked by one or two deep fissures, and the inferior border which surrounds the base is also sharp. The colour of the lungs is pinkish grey, mottled, and variously marked with black. The surface is figured with irregularly polygonal outlines, which represent the lobules of the organ, and the area of each of these polygonal spaces is crossed by lighter lines. Each lung is divided into two lobes, by a long and deep fissure, which extends from the posterior surface of the upper part of the organ, downwards and forwards to near the anterior angle of its base. In the right lung the upper lobe is subdivided by a second fissure, which extends obliquely forwards from the middle of the preceding to anterior border of the organ, and marks off a small triangular obe. The right lung is larger than the left, in consequence of the inclina- tion of the heart to the left side. It is also shorter, from the great convexity of the liver, which presses the diaphragm upwards upon the right side of the chest considerably above the level of the left; and has three lobes. The left lung is smaller, has but two lobes, but is longer than the right. Each lung is retained in its place by its root, which is formed by the pulmonary artery, pulmonary veins and bronchial tubes, together with the bronchial vessels and pulmonary plexuses of nerves. The large vessels of the root of each lung are arranged in a similar order from before, backwards, on both sides, viz. Pulmonary veins, Pulmonary artery, Bronchus. From above, downwards, on the right side this order is exactly re- versed; but on the /eft side the bronchus has to stoop beneath the arch of the aorta, which alters its position to the vessels. They are thus disposed on the two sides :— Right. Left. Bronchus, Artery, Artery, Bronchus, Veins. Veins. Structure.—The lungs are composed of the ramifications of the bronchial tubes which terminate in bronchial cells (air cells), of the ramifications of the pulmonary artery and veins, bronchial arteries and veins, lymphatics and nerves; the whole of these structures being held together by areolar tissue, constitute the parenchyma. The parenchyma of the lungs, when examined on the surface or by means of a section, is seen to consist of small polygonal divisions, or lobules, which are connected to each other by an inter-lobular areolar tissue. These 552 BRONCHIAL TUBES,—PLEURZ. lobules again consist of smaller lobules, and the latter are formed by a cluster of air cells, in the parietes of which the capillaries of the pul- monary artery and pulmonary veins are distributed. Bronchial tubes. — The two bronchi proceed from the bifurcation of the trachea to their corresponding lungs. The right takes its course nearly at right angles with the trachea, and enters the upper part of the right lung ; while the left, longer and smaller than the right, passes obliquely beneath the arch of the aorta, and enters the lung at about the middle of its root. Upon entering the lungs they divide into two branches, and each of these divides and subdivides dichotomously to their ultimate termination in small dilated sacs, the bronchial or pul- monary cells. The fibro-cartilaginous rings which are observed in the trachea become incomplete and irregular in shape in the bronchi, and in the smaller bronchial tubes are lost altogether. At the termination of these tubes the fibrous and muscular coats become extremely thin, and are probably continued upon the lining mucous membrane of the air cells. : The Pulmonary artery, conveying the dark and impure venous blood to the lungs, terminates in capillary vessels, which form a minute net- work upon the parietes of the bronchial cells, and then converge to form the pulmonary veins, by which the arterial blood, purified in its passage through the capillaries, is returned to the left auricle of the eart. The Bronchial arteries, branches of the thoracic aorta, ramify upon the bronchial tubes and in the tissue of the lungs, and supply them with nutrition, while the venous blood is returned by the bronchial veins to the vena azygos. The Lymphatics, commencing upon the surface and in the substance of the lungs, terminate in the bronchial glands. These glands, very _ numerous and often of large size, are placed at the roots of the lungs, around the bronchi, and at the bifurcation of the trachea. In early life they resemble lymphatic glands in other situations; but in old age, and often in the adult, are quite black, and filled with carbon- aceous matter, and occasionally with calcareous deposits. The Nerves are derived from the pneumogastric and sympathetic. They form two plexuses, anterior pulmonary plexus, situated upon the front of the root of the lungs, and composed chiefly of filaments from the great cardiac plexus ; and posterior pulmonary pleaus on the posterior aspect of the root of the lungs, composed principally of branches from the pneumogastric. The branches from these plexuses follow the course of the bronchial tubes, and are distributed to the bronchial cells. PLEURA. Each lung is enclosed, and its structure maintained, by a serous membrane, the pleura, which invests it as far as the root, and is then reflected upon the parietes of the chest. That portion of the eee oe . MEDIASTINUM.—ABDOMEN. 553 membrane which is in relation with the lung is called plewra pulmo- nalis, and that in contact with the parietes, pleura costalis. The re- flected portion, besides forming the internal lining to the ribs and in- tercostal muscles, also covers the diaphragm and the thoracic surface of the vessels at the root of the neck. The pleura must be dissected from off the root of the lung, to see the vessels by which it is formed and the pulmonary plexuses. MEDIASTINUM, The approximation of the two reflected pleure in the middle line of the thorax forms a septum, which divides the chest into the two pulmonary cavities. This is the mediastinum. The two pleure are not, however, in contact with each other at the middle line in the formation of the mediastinum, but leave a space between them which contains all the viscera of the chest with the exception of the lungs. The mediastinum is divided into the anterior, middle, and posterior. The Anterior mediastinum is a triangular space, bounded in front by the sternum, and on each side by the pleura. It contains a quantity of loose areolar tissue, in which are found some lymphatic glands and vessels passing upwards from the liver; the remains of the thymus gland, the origins of the sterno-hyoid, sterno-thyroid, and triangularis sterni muscles, and the internal mammary vessels of the left side. The Middle mediastinum contains the heart enclosed in its peri- cardium ; the ascending aorta; the superior vena cava ; the bifurca- tion of the trachea ; the pulmonary arteries and veins ; and the phrenic nerves. The Posterior mediastinum is bounded behind by the vertebral column, in front by the pericardium, and on each side by the pleura. It contains the descending aorta; the greater and lesser azygos veins, the superior intercostal vein ; the thoracic duct ; the cesophagus and pneumogastric nerves ; and the great splanchnic nerves. ABDOMEN, The abdomen is the inferior cavity of the trunk of the body; it is bounded in front and at the sides by the lower ribs and abdominal muscles ; behind, by the vertebral column and abdominal muscles ; above, by the diaphragm ; and, below, by the pelvis: and contains the alimentary canal, the organs subservient to digestion, viz. the liver, pancreas, and spleen; and the organs of excretion, the kidneys, with the supra-renal capsules. Regions.— For convenience of description of the viscera, and for re- ference to the morbid affections of this cavity, the abdomen is divided into certain districts or regions. Thus, if two transverse lines be carried around the body, the one parallel with the convexities of the 554 PERITONEUM. ribs, the other with the highest points of the crests of the ilia, the abdomen will be divided into three zones. Again, if a perpendicular line be drawn at each side, from the cartilage of the eighth rib to the middle of Poupart’s ligament, the three primary zones will each be subdivided into three compartments or regions, a middle and two lateral. The middle region of the upper zone being immediately over the small end of the stomach, is called epigastric (tai yaornp, over the stomach). The two lateral regions being under the cartilages of the ribs are called hypochondriac (ixé xévdeo, under the cartilages). The middle region of the middle zone is the wmbilical; the two lateral, the lumbar. The middle region of the inferior zone is the hypogastric (ix¢ yarrne, below the stomach); and the two lateral, the diac. In addition to these divisions, we employ the term inguinal region, in reference to the vicinity of Poupart’s ligament. Position of the Viscera.—In the upper zone will be seen the liver, extending across from the right to the left side; the stomach and spleen on the left, and the pancreas and duodenum behind. In the middle zone is the transverse portion of the colon, with the upper part of the ascending and descending colon, omentum, small intestines, mesentery, and, behind, the kidneys and supra-renal capsules. In the inferior zone is the lower part of the omentum and small intes- tines, the caecum, ascending and descending colon with the sigmoid flexure, and ureters. The smooth and polished surface, which the viscera and parietes of the abdomen present, is due to the peritoneum, which should in the next place be studied. PERITONEUM. The Peritoneum (segirsivesy, to extend around) is a serous membrane, and therefore a shut sac: a single exception exists in the human subject to this character, viz. in the female, where the peritoneum is perforated by the open extremities of the Fallopian tubes, and is con- tinuous with their mucous lining. The simplest idea that can be given of a serous membrane, which may apply equally to all, is, that it invests the viscus or viscera, and is then reflected upon the parietes of the containing cavity. If the cavity contain only a single viscus, the consideration of the serous membrane is extremely simple. But in the abdomen, where there are a number of viscera, the serous membrane passes from one to the other until it has invested the whole, before it is reflected on the parietes. Hence its reflexions are a little more complicated. In tracing the reflexions of the peritoneum in the middle line, we commence with the diaphragm, which is lined by two layers, one from the parietes in front, anterior, and one from the parietes behind, posterior, These two layers of the same membrane, at the posterior part of the diaphragm, descend to the upper surface of the liver, PERITONEUM. 555 forming the coronary and lateral ligaments of the liver. They then surround the liver, one going in front, the other behind that viscus, and, meeting at its under surface, pass to the stomach, forming the Fig. 167.* * The reflexions of the peritoneum. D. The diaphragm, S. The stomach. C. The transverse colon. D. The transverse duodenum. P. The pancreas. I. The small intestines. R. The rectum. B. The urinary bladder. 1. The anterior layer of the peritoneum, lining the under surface of the diaphragm. 2. The posterior layer. 3. The coronary ligament, formed by the passage of these two layers to the posterior border of the liver. 4. The lesser omentum ; the two layers passing fins the under surface of the liver to the lesser curve of the stomach. 5. The two layers meeting at the greater curve, then passing downwards and returning upon themselves, forming (6) the greater omentum. 7. The transverse meso-colon. 8. The posterior layer traced upwards in front 556 PERITONEUM.—DUPLICATURES. lesser omentum. They then, in the same manner, surround the stomach, and meeting at its lower border, descend for some distance in front of the intestines, and return to the transverse colon, forming the great omentum; they then surround the transverse colon, and pass directly backwards to the vertebral column, forming the transverse meso-colon. Here the two layers separate ; the posterior ascends in front of the pancreas and aorta, and returns to the posterior part of the diaphragm, where it becomes the posterior layer with which we commenced. The anterior descends, invests all the small intestines, and returning to the vertebral column forms the mesentery. It then descends into the pelvis in front of the rectum, which it holds in its place by means of a fold called meso-rectum, forms a pouch, the recto- vesical fold, between the rectum and bladder, ascends upon the poste- rior surface of the bladder, forming its false ligaments, and returns upon the anterior parietes of the abdomen to the diaphragm, whence we first traced it. In the female, after descending into the pelvis in front of the rectum, it is reflected upon the posterior surface of the vagina and uterus. It then descends on the anterior surface of the uterus, and forms at either side the broad ligaments of that organ. From the uterus it ascends upon the ‘posterior surface of the bladder and an- terior parietes of the abdomen, and is continued, as in the male, to the diaphragm. In this way the continuity of the peritoneum, as a whole, is dis- tinctly shown, and it matters not where the examination commence or where it terminate, still the same continuity of surface will be discernible throughout. If we trace it from side to side of the ab- domen, we may commence at the umbilicus ; we then follow it out- wards lining the inner side of the parietes to the ascending colon; it surrounds that intestine ; it then surrounds the small intestine, and returning on itself forms the mesentery. It then invests the descending colon, and reaches the parietes on the opposite side of the abdomen, whence it may be traced to the exact point from which we started, The viscera, which are thus shown to be invested by the peritoneum in its course from above downwards, are the— Liver, Stomach, Transverse colon, Small intestines, Pelvic viscera. of D, the transverse duodenum, and P, the pancreas, to become continuous with the posterior layer (2). 9. The foramen of Winslow; the dotted line bounding this foramen inferiorly marks the course of the hepatic artery for- wards, to enter between the layers of the lesser omentum. 10. ‘The mesentery encircling the small intestine. 11. The recto-vesical fold, formed by the de- scending anterior layer. 12. The anterior layer traced upwards upon the in- ternal surface of the abdominal parietes to the layer (1), with which the exa- mination commenced. FORAMEN OF WINSLOW. 557 The folds, formed between these and between the diaphragm and the liver, are— : (Diaphragm.) Broad, coronary, and lateral ligaments. (Liver. ) Lesser omentum. ( Stomach.) Greater omentum. (Transverse colon.) Transverse meso-colon, Mesentery, Meso-rectum, Recto-vesical fold, False ligaments of the bladder. - And in the female, the— Broad ligaments of the uterus. The ligaments of the liver will be examined with that organ. The Lesser omentum is the duplicature passing between the liver and the upper border of the stomach. It is extremely thin, excepting oa its right border, where it is free, and contains between its layers, the— Hepatic artery, Ductus communis choledochus, Portal vein, Hepatic plexus of nerves, Lymphatics. These structures are enclosed in a loose areolar tissue, called Glisson’s capsule.* The relative position of the three vessels is, the artery to the left, the duct to the right, and the vein between and behind. If the finger be introduced behind this right border of the lesser omentum, it will be situated in an opening called the foramen of Winslow.+ In front of the finger will lie the right border of the lesser omentum ; behind it the diaphragm, covered by the ascending or posterior layer of the peritoneum ; below, the hepatic artery, curving forwards from the cceliac axis ; and above, the lobus Spigelii. These, therefore, are the boundaries of the foramen of Winslow, which is no- thing more than a constriction of the general cavity of the peritoneum * Francis Glisson, Professor of Medicine in the University of Cambridge. His work, ‘‘ De Anatomia Hepatis,” was published in 1654. + Jacob Benignus Winslow: his “‘ Exposition Anatomique de la Structure du Corps Humain,’’ was published in Paris in 1732. 558 OMENTUM.—MESO-COLON.—MESENTERY. at this point, arising out of the necessity for the hepatic. and gastric arteries to pass forwards from the cceliac axis to reach their respective viscera. If air be blown through the foramen of Winslow, it will descend behind the lesser omentum and stomach to the space between the descending and ascending pair of layers, forming the great omentum. This is sometimes called the lesser cavity of the peritoneum, and that external to the foramen the greater cavity ; in which case the fora- men is considered as the means of communication between the two. There is a great objection to this division, as it might lead the inex- perienced to believe that there were really two cavities. There is but one only, the foramen of Winslow being merely a constriction of that one, to facilitate the communication between the nutrient arteries and the viscera of the upper part of the abdomen. The Great omentum consists of four layers of peritonewm, the two which descend from the stomach, and the same two, returning upon themselves to the transverse colon. A quantity of adipose substance is deposited around the vessels which ramify through its structure. It would appear to perform a double function in the economy. Ist. Protecting the intestines from cold; and, 2ndly. Facilitating the movement of the intestines upon each other during their vermicular action. The Transverse meso-colon (utoos, middle, being attached to the middle of the cylinder of the intestine) is the medium of connection between the transverse colon and the posterior wall of the abdomen. It also affords to the nutrient arteries a passage to reach the intestine, and encloses between its layers, at the posterior part, the transverse portion of the duodenum. The Mesentery (uécov tvregov, being connected to the middle of the cylinder of the small intestine) is the medium of connection between the small intestines and the posterior wall of the abdomen. It is ob- lique in its direction, being attached to the posterior wall, from the left side of the second lumbar vertebra to the right iliac fossa. It retains the small intestines in their places, and gives passages to the mesenteric arteries, veins, nerves, and lymphatics. The Meso-rectum, in like manner, retains the rectum in connection with the front of the sacrum. Besides this, there are some minor folds in the pelvis, as the recto-vesical fold, the false ligaments of the bladder, and the broad ligaments of the uterus. The Appendices epiploice are small irregular pouches of the perito- neum, filled with fat, and situated like fringes upon the large intestine. Three other duplicatures of the peritoneum are situated in the sides of the abdomen ; they are the gastro-phrenic ligament, the gastro-splenic omentum, the ascending and descending meso-colon. The gastro- phrenic ligament is a small duplicature of the peritoneum, which de- scends from the diaphragm to the extremity of the cesophagus, and lesser curve of the stomach. The gastro-splenic omentum is the dupli- cature which connects the spleen to the stomach. The ascending ————oro ee ee es ALIMENTARY CANAL. ~~ §59 meso-colon is the fold which connects the upper part of the ascending colon with the posterior wall of the abdomen; and the descending meso-colon, that which retains the sigmoid flexure in connection with the abdominal wall. Structure of serous membrane.—Serous membrane consists of two layers, an external or fibro-cellular layer, and an internal layer or epithelium. The fibro-cellular layer upon its outer surface is rough and vascular, and adherent to surrounding structures; but on its inner surface is dense and smooth, and wholly deficient of vessels carrying red blood. The smooth and brilliant surface of serous mem- brane is due to a distinct epithelium, which has been shown by the ex- cellent researches of Henle, to be composed of laminz of vesicles, and flattened polygonal scales with central nuclei, like the epidermis and epithelium of mucous membrane. Dr. Henle has observed this struc- ture, which may be easily demonstrated with a good microscope upon the surface of all the serous membranes of the body, upon the surface of the lining membrane of arteries and veins, and upon synovial membranes. The general characters of a serous membrane are its resemblance to a shut sac, and its secretion of a peculiar fluid, resembling the serum of the blood ; but the former of these characters is not absolutely essential to the identity of a serous membrane; for, as we have shown above, the peritoneum in the female is perforated by the ex- tremities of the Fallopian tubes ; while in aquatic reptiles there is a direct communication between its cavity and the medium in which they live. From the variable nature of the secretion of these membranes, they have been divided into two classes, the true serous membranes, viz. the arachnoid, pericardium, pleurz, peritoneum, and tunice vaginales, which pour out a secretion containing but a small portion of albumen ; and the synovial membranes and burs, which secrete a fluid contain- ing a larger quantity of albumen. ALIMENTARY CANAL. The Alimentary canal is a musculo-membranous tube, extending from the mouth to the anus. It is variously named in the different parts of its course ; hence it is divided into the Mouth, Pharynx, (Esophagus, Stomach, Duodenum, Small intestine | Jejunum, Tleum. Czecum, Large intestine< Colon, Rectum. 560 HARD PALATE.—SOFT PALATE. The Mouth is the irregular cavity which contains the organs of taste and the principal instruments of mastication. It is bounded im Sront by the lips; on either side by the internal surface of the cheeks ; above by the hard palate and teeth of the upper jaw ; below by the tongue, by the mucous membrane stretched between the arch of the lower jaw and the under surface of the tongue, and by the teeth of the inferior maxilla; and behind by the soft palate and fauces. The Lips are two fleshy folds formed externally by common integu- ment, and internally by mucous membrane, and containing between these two layers the muscles of the lips, a quantity of fat, and numer- ous small labial glands. They are attached to the surface of the upper and lower jaw, and each lip is connected to the gum in the middle line by a fold of mucous membrane, the freenum labii superioris and freenum labii inferioris, the former being the larger. The Cheeks (buccz) are continuous on either hand with the lips, and form the sides of the face; they are composed of integument, a large quantity of fat, muscles, mucous membrane, and buccal glands. The mucous membrane lining the cheeks is reflected above and below upon the sides of the jaws, and is attached posteriorly to the anterior margin of the ramus of the lower jaw. At about its middle, opposite the second molar tooth of the upper jaw, is a papilla, upon which may be observed a small opening, the aperture of the duct of the parotid gland. The Hard palate is a dense structure, composed of mucous membrane, palatal glands, fibrous tissue, vessels, and nerves, and firmly connected to the palate processes of the superior maxillary and palate bones. It is bounded in front and on each side by the alveolar processes and gums, and is continuous behind with the soft palate. Along the middle line it is marked by an elevated raphé, and presents upon each side of the raphé a number of transverse ridges and grooves. Near its anterior extremity, and immediately behind the middle incisor teeth, is a papilla which corresponds with the termination of the naso- palatine canal, and has been supposed to be endowed with a peculiar sensibility, The Gums are composed of a thick and dense mucous membrane, which is closely adherent to the periosteum of the alveolar processes, and embraces the necks of the teeth. They are remarkable for their hardness and insensibility; and for their close contact, without ad- hesion, to the surface of the tooth. From the neck of the tooth they are reflected into the alveolus, and become continuous with the peri- osteal membrane of that cavity. The Tongue has been already described as an organ of sense; it is invested by mucous membrane, which is reflected from its under part upon the inner surface of the lower jaw, and constitutes, with the muscles beneath, the floor of the mouth. Upon the under surface of the tongue, near its anterior part, the mucous membrane forms a con- siderable fold, which is called the franum lingue; and on each side of the fraenum is a large papilla, the commencement of the duct of the Weimer ad TONSILS.—PAROTID GLAND. 561 submaxillary gland, and several smaller openings, the ducts of the sub- lingual gland. The Soft palate (velum pendulum palati) is a fold of mucous mem- brane situated at the posterior part of the mouth. It is continuous, superiorly, with the hard palate, and is composed of mucous membrane, palatal glands, and muscles. Hanging from the middle of its inferior border is a small rounded process, the wvula; and passing outwards from the uvula on each side are two curved folds of the mucous mem- brane, the arches, or pillars of the palate. The anterior pillar is con- tinued downwards to the side of the base of the tongue, and is formed by the projection of the palato-glossus muscle. The posterior pillar is prolonged downwards and backwards into the pharynx, and is formed by the convexity of the palato-pharyngeus muscle. These two pillars, closely united above, are separated below by a triangular interval or niche, in which the tonsil is lodged. The Tonsils (amygdale) are two glandular organs, shaped like almonds, and situated between the anterior and posterior pillar of the soft palate, on each side of the fauces. They are cellular in texture, and composed of an assemblage of mucous follicles, which open upon the surface of the gland. Externally, they are invested by the pharyngeal fascia, which separates them from the superior constrictor muscle and internal carotid artery, and prevents an abscess from open- ing in that direction. In relation to surrounding parts, they correspond with the angle of the lower jaw. The space included between the soft palate and the root of the tongue is the isthmus of the fauces. It is bounded above by the soft palate ; on each side by the pillars of the soft palate and tonsils; and below by the root of the tongue. It is the opening between the mouth and pharynx. SALIVARY GLANDS. Communicating with the mouth are the excretory ducts of three pairs of salivary glands, the parotid, submaxillary, and sublingual. The Parotid gland (wapz, near, ods, dros, the ear,) the largest of the three, is situated immediately in front of the external ear, and extends superficially for a short distance over the masseter muscle, and deeply behind the ramus of the lower jaw. It reaches inferiorly to below the level of the angle of the lower jaw, and posteriorly to the mastoid process, slightly overlapping the insertion of the sterno-mastoid muscle. Embedded in its substance are the external carotid artery, temporo- maxillary vein, and facial nerve; emerging from its anterior border, the transverse facial artery and branches of the pes anserinus; and above, the temporal artery. The duct of the parotid gland (Stenon’s* duct) commences at the * Nicholas Stenon, an anatomist of great research. He discovered the paro- tid duct while in Paris. He was appointed professor of Medicine in Copen- 20 562 SUBMAXILLARY GLAND.—SUBLINGUAL GLAND. papilla upon the internal surface of the cheek, opposite the second molar tooth of the upper jaw; and, piercing the buccinator muscle, crosses the masseter to the anterior border of the gland, where it divides into several branches, which subdivide and ramify through its structure, to terminate in the small cecal pouches of which the gland is composed. A small branch is generally given off from the duct while crossing the masseter muscle, which forms, by its ramifications and terminal dilatations, a small glandular appendage, the socia parotidis. Stenon’s duct is remarkably dense and of considerable thickness, while the area of its canal is extremely small. The Submazillary gland is situated in the posterior angle of the submaxillary triangle of the neck. It rests upon the hyo-glossus and mylo-hyoideus muscles, and is covered in by the body of the lower jaw and by the deep cervical fascia. It is separated from the parotid gland by the stylo-maxillary ligament, and from the sublingual by the mylo- hyoideus muscle. Embedded among its lobules are the facial artery and submaxillary ganglion. . The excretory duct (Wharton’s) of the submaxillary gland com- mences upon the papilla, by the side of the freenum linguze, and passes backwards beneath the mylo-hyoideus and resting upon the hyo-glossus muscle, to the middle of the gland, where it divides into numerous branches, which ramify through the structure of the gland to its caecal terminations. It lies in its course against the mucous membrane forming the floor of the mouth, and causes a prominence of that membrane. The Sublingual is an elongated and flattened gland, situated beneath the mucous membrane of the floor of the mouth, on each side of the frenum lingue. It is in relation above with the mucous membrane ; in front with the depression by the side of the symphysis of the lower jaw ; eaternally with the mylo-hyoideus muscle; and internally with the hypoglossal nerve and genio-hyo-glossus muscle. It pours its secretion into the mouth by seven or eight small ducts, which commence by small openings on each side of the frenum linguee. Structure.—The salivary are conglomerate glands, consisting of ee which are made up of polygonal lobules, and these of still smaller obules. The smallest lobule is apparently composed of granules, which are - minute cecal pouches, formed by the dilatation of the extreme ramifi- cations of the ducts. These minute ducts unite to form lobular ducts, and the lobular ducts constitute by their union a single excretory duct. The cecal pouches are connected by areolar tissue, so as to form a minute lobule; the lobules are held together by a more con- densed areolar layer; and the larger lobes are enveloped by a dense cellulo-fibrous capsule, which is firmly attached to the deep cervical fascia. hagen in 1672. His work, ‘De Musculis et Glandulis Observationes,’’ was published in 1664, PHARYNX.—ITS OPENINGS. 563 Vessels and Nerves.—The parotid gland is abundantly supplied with arteries by the external carotid; the submaxillary by facial; and the sublingual by the sublingual branch of the lingual artery. The Nerves of the parotid gland are derived from the auricular branch of the inferior maxillary, from the auricularis magnus, and from the nervi molles of the external carotid artery. The submax- illary gland is supplied by the branches of the submaxillary gan- glion, and by filaments from the mylo-hyoidean nerve; and the sub- lingual by filaments from the submaxillary ganglion and gustatory nerve. . PHARYNX. The pharynx (¢déevy%, the throat) is a musculo-membranous sac, situated upon the cervical portion of‘the vertebral column, and extend- ing from the base of the skull to a point corresponding with the cricoid cartilage in front, and the fifth cervical vertebra behind. It is composed of mucous membrane, muscles, vessels, and nerves, and is invested by a strong fascia, situated between the mucous membrane and muscles, which serves to connect it with the basilar process of the occipital bone and with the petrous portions of the temporal bones. Upon its anterior part it is incom- plete, and has opening into it seven foramina, viz. Posterior nares, two, Eustachian tubes, two, Mouth, Larynx, (Esophagus, The Posterior nares are the two large openings at the upper and front part of the pharynx. On each side of these openings, and slightly * The pharynx laid open from behind. 1. A section carried transversely through the base of the skull. 2, 2. The walls of the pharynx drawn to each side. 3,3. The posterior nares, separated by the vomer. 4. The extremity of the Eustachian tube of one side. 5. The soft palate. 6. The posterior pillar of the soft palate. 7. Its anterior pillar; the tonsil is seen situated in the niche between the two pillars. 8. The root of the tongue, partly concealed by the uvula. 9. The epiglottis, overhanging (10) the cordiform opening of the larynx. 11. The posterior part of the larynx. 12. The opening into the ceso- phagus. 13. The external surface of the esophagus. 14. The trachea. 564 THE STOMACH. above the posterior termination of the inferior turbinated bone, is the irregular depression in the mucous membrane, marking the entrance of the Lustachian tube. Beneath the posterior nares is the large opening into the mouth, partly veiled by the soft palate; and, beneath the root of the tongue, the cordiform opening of the larynx. The esophageal opening is the lower constricted portion of the pharynx. Csophagus.—The cesophagus (oie, to bear, Pavey, to eat), is a slightly flexuous canal, inclining to the left in the neck, to the right in the upper part of the thorax,* and again to the left in its course through the posterior mediastinum ; it commences at the termination of the pharynx, opposite the lower border of the cricoid cartilage and fifth cervical vertebra, and descends the neck: behind and rather to the left of the trachea. It then passes behind the arch of the aorta, and along the posterior mediastinum, lying in front of the thoracic aorta, to the cesophageal opening in the diaphragm, where it enters the ab- domen, and terminates at the cardiac orifice of the stomach at a point about opposite the tenth dorsal vertebra. The cesophagus is flattened and narrow in the cervical region, and cylindrical in the rest of its course ; its largest diameter is met with near the lower part of its course. THE STOMACH. The stomach is an expansion of the alimentary canal, situated in the left hypochondriac, and extending into the epigastric region. It is directed somewhat obliquely from above downwards, from left to right, and from before backwards ; and in the female, where the injurious sys- tem of tight-lacing has been pursued, is longer than in the male. On account of the peculiarity of its form, it is divided into a greater or splenic, and a lesser or pyloric, end; a lesser curvature above, and a greater curvature below; an anterior and a posterior surface; a cardiac orifice, and a pyloric orifice. The great end is not only of large size, but expands beyond the point of entrance of the cesophagus, and is embraced by the concave surface of the spleen. The pylorus is the small and contracted extremity of the organ; near its extremity is a small dilatation which was called by Willis the antrum of the py- lorus. The two curvatures give attachment to the peritoneum; the upper curve to the lesser omentum, and the lower to the greater omen-_ tum. The anterior surface looks upwards and forwards, and is in re- lation with the diaphragm, which separates it from the viscera of the thorax and from the six lower ribs, with the left lobe of the liver, and in the epigastric region, with the abdominal parietes. The posterior sur- face looks downwards and backwards, and is in relation with the dia- phragm, the pancreas, the third portion of the duodenum, the trans- verse meso-colon, the left kidney, and left supra-renal capsule; this sur- * Cruveilhier remarks that this inflexion explains the obstruction which a hougie soca meets with in its passage along the cesophagus opposite the rst rib. — = THE DUODENUM. 565 face forms the anterior boundary of that cul-de-sac of the peritoneum which is situated behind the lesser omentum and extends into the greater omentum, SMALL INTESTINES. The small intestine is about twenty-five feet in length, and is divi- sible into three portions, duodenum, jejunum, and ileum. Fig. 169.* ‘ wall Mijn! ZZ M\ i ee WF hit iy) oN) Wy 3 an al ‘eal Ns ) gis The Duodenum (called 3w3exadaxrv20v by Herophilus) is somewhat larger than the rest of the small intestines, and has received its name from being about equal in length to the breadth of twelve fingers. Commencing at the pylorus, it ascends obliquely backwards to the un- der surface of the liver; it next descends perpendicularly in front of the * A vertical and longitudinal section of the stomach and duodenum, made in such a direction as to include the two orifices of the stomach. 1. The cesopha- ; upon its internal surface the plicated arrangement of the cuticular epithe- lium is shewn. 2. The cardiac orifice of the stomach, around which the fringed border of the cuticular epithelium is seen. 3. The ye end of the stomach. 4. Its lesser or pyloric end. 5. The lesser curve. 6. The greater curve. 7. The dilatation at the lesser end of the stomach, which has received from Willis the name of antrum of the pylorus. This may be regarded as the rudiment of asecond stomach. 8. The ruge of the stomach formed by the mucous mem- brane : their longitudinal direction is shewn. 9. The pylorus. 10. The oblique portion of the duodenum. 11. The descending portion. 12. The pancreatic duct and the ductus communis choledochus close to their termination. 13. The papilla upon which the ducts open. 14, The transverse portion of the duodenum. 15. The commencement of the jejunum. In the interior of the duodenum and jejunum, the valvulze conniventes are seen. 566 JEJUNUM.—ILEUM. right kidney, and then passes nearly transversely across the third lumbar vertebra; terminating in the jejunum on the left side of the second lumbar vertebra, where it is crossed by the superior mesenteric artery and vein. The first or oblique portion of its course, between two and three inches, is completely enclosed by the peritoneum: it is in re- lation, above with the liver and neck of the gall-bladder; in front with the greater omentum and abdominal parietes; and behind with the right border of the lesser omentum and its vessels. The second or perpendicular portion is situated altogether behind the peritoneum ; it is in relation by its anterior surface with the commencement of the arch of the colon; by its posterior surface with the concave margin of the right kidney, the inferior vena cava, and the ductus communis chole- dochus ; by its right border with the ascending colon; and by its defé border with the pancreas. The ductus communis choledochus and pan- creatic duct open into the internal and posterior side of the perpendi- cular portion, a little below its middle. The third or transverse por- tion of the duodenum lies between the diverging layers of the trans- vers meso-colon, with which and with the stomach it is in relation in Jront; above it is in contact with the lower border of the pancreas, the superior mesenteric artery and vein being interposed; and behind it rests upon the inferior vena cava and aorta. The Jejunum (jejunus, empty) is named from being generally found empty. It forms the upper two-fifths of the small intestine ; commencing at the duodenum on the left side of the second lumbar vertebra, and terminating in the ileum. It is thicker to the touch than the rest of the intestine, and has a pinkish tinge from containing more mucous membrane than the ileum. The Jleuwm ( =a medium - 104 unguis . . ethmoides : . +. $9 vertebra dentata . 7 a ee Tee prominens . 13 fibula . ; . oe vertebre cervical . I] frontale . 4 . ae dorsal a humerus . " eas lumbar. ‘14 hyoides . ; a ieee vomer . . 4 ilium . ‘ ~ es Wormiana . . ~oe innominatum . . 89 | Botal, foramen of . . 624. ischium . ; 3 age notice of . 624 lachrymale . - 45 | Bowman, Mr., researches of, magnum , 5 eG 16], 591 malare . . . 45 | Brain : > ” -. 405 maxillare superius . 41 | Bronchi . : i . 582 inferius . 50 | Bronchialcells . i . 551 metacarpus. 4 ee tubes . ‘ . 552 metatarsus » 105 | Bronchocele : : . 549 nasi , ; . 41 | Bruna, Von, notice of . om naviculare : . 103 | Brunner’s glands ‘ . SE occipitale ‘ . 21 | Bulb, corpus spongiosum . 598 palati . 3 . 46 Bulbi fornicis . 424 parictale q . 24 | Bulbous part of the urethra. 601 patella . . 98 | Bulbus olfactorius . - 436° phalanges mantis . 88 | Burse mucose . . . WT pedis . 107 pisiforme . . 84 pobia i. whire ~ 91 | Caecum . ‘ » . bee radius. ‘ . 81 | Calamus scriptorius . . 420 sacrum . - 18 | Calices . ; - 590 scaphoides carpi - 82 | Camper’s ligament ‘ . 283> tarsi. . 103 | Canalof Fontana . . 497 scapula . ; etre Petit gisin . 502 semi-lunare . +e Sylvius ‘ . 418 sesamoidea mantis . 107 | Canals of Havers : ; 2 pedis . 107 | Canthi. ; ; . 50 sphenoides - 85 | Capillaries : : . 293% sternum . . . 71 | Capitula laryngis . -.. Sey tarsus . . . 101 | Capsule of Glisson . 578. 580 — temporal é . 29 | Capsules supra-renal 587. 625 tibia. ~ --« 98 | Caput er . . aaa trapezoides . - 85 | Cardia. ‘ . 564 trapezium é - 84 | Carpus. : ee ie triquetra - + 653 | Cartilage . : eee a, INDEX. 633 CARTILAGES. Page Page inter-articular of cla- Conarium . : : - 419 vicle . . 135.136 | Concha . - 507 inter-articular of jaw 126 | Congestion of the liver . 584 inter-articular of wrist 141 | Conirenales . ‘ - 589 semi-lunar : . 149 vasculosi . : - 605 inification 3 ‘ 5 | Conjunctiva : ; . 504 Caruncula lachrymalis - 505 | Converging fibres ‘ - 430 mamillaris . 436 | Cooper, Sir Astley, researches, Caruncule myrtiformes . 613 450. 604. 620 Casserian ganglion . . 439 | Corium . : : . $§21 Cauda equina . A . 432 | Cornea . ; . 496 Cava, vena « . « 879 | Cornicula laryngis oie 642 Cementum j . . + 65 | Cornu Ammonis - 415 Centrum ovale . ‘ - 411 | Cornua of the ventricles . 411 Cerebellum : ; - 420 | Corona glandis . ; . 697 Cerebro-spinal axis. - 399 | Coronary valve . ; - 533 Cerebrum . ‘ - 410 | Corpora albicantia . . 424 Ceruminous follicles é . 508 Arantii . . 536. 538 Cervical ganglia . : . 485 cavernosa . 598 Chambers of the eye . . 501 geniculata . . 417 Cheeks. = . 560 Malpighiana . 587. 590 Chiasma nerv. opticor. - 427 mamillaria . . 424 Chorde longitudinales . 411 olivaria. . . 426 tendinee . 535, 537 pisiformia . . 424 vocales . : . 544 pyramidalia . . 426 Willisii Higa oc eel quadrigemina . 418 Choroid membrane . . 496 restiformia 422. 427 plexus. 5 ).. 413 strinta Yak te. ies Cilia ee - + 504 | Corpus callosum . ‘ Rihest 3 f Ciliary canal. : - 497 cavernosum . 598 ligament ‘ . 497 dentatum - 422. 427 processes ertis} 1 0408 fimbriatum . 414. 417 Circle of Willis. . . 317 geniculatum . ae (tS Circulation, adult ‘ . 531 Highmorianum . 604 foetal : . 616 luteum . : - 612 Circulus tonsillaris . . 449 psalloides «eS aT Clitoris. ; - 613 rhomboideum *. . 422 Clivus Blumenbachii ‘ . 93d spongiosum. . 598 Cochlea . ‘ . 3515 striatum . ; . 413 Cock, Mr., researches of, 451 | Costal cartilages. . aie Coeliac axis ; ‘ . 93833 | Cotunnius, notice of, . 3 BIS Colon é é ‘ - 567 | Cowper’s glands ; . 601 Columna nasi. ’ - 491 | Cranial nerves . , . 434 Columnz carnez . 535. 537 | Cribriform fascia ; * 288 papillares . 536 | Cricoid cartilage ° . 542 Commissures . . 41 8. 430 Crico-thyroid membrane 543 great . 411. 430 | Cruracerebelli . . 422. 426 634 Crura cerebri penis Crural canal ring : Crystalline lens . Cuneiform cartilages Cupola Curling, Mr., researches of, Cuticle : ; Cutis Cystic duct Cytoblast . Dartos : Davy, Dr., researches of, Derbyshire neck Dermis . ‘ Detrusor urine . Diaphragm Diaphysis « Diarthrosis Digital cavity Diverging fibres . Dorsi-spinal veins Ductus ad nasum arteriosus comm. choledochus . cysticus . ejaculatorius .« hepaticus ‘ ‘ lymphaticus dexter pancreaticus prostaticus thoracicus venosus . Duodenum Dura mater * Ejaculatory duct ‘ Elastic tissue ‘ Enamel Enarthrosis Encephalon Endolymph 4 Ensiform cartilage . Entozoon folliculorum 523, 616. 597. | 406. 597. INDEX Page 424 | Epidermis 597 | Epididymis 288 | Epigastric region 289 | Epiglottic gland 501 | Epiglottis . : . 542 | Epiglotto-hyoidean ligament 515 | Epiphysis . : : 626 | Epithelium : 522 | Erectile tissue 521 | Eustachian tube 585 valve 570 ee notice ts Eye . 602 brows 316 globe . 549 lashes 521 lids 594 | 218 | Falciform process 8 | Fallopian tubes . 110 | Fallopius, notice of, 414 | Falx cerebelli 427 cerebri 383 | Fasc, 506 general anatomy of 624 cervical . 585 cribriform 585 dentata 606 iliaca. R 585 inter-columnar 397 lata 586 lumbar . 596 _ obturator 396 palmar . 616 pelvica . 565 perineal 431 plantar . : : propria . . 280. : 506 recto-vesical . ‘ 606 spermatica . 212. 116 temporal ‘ 56 thoracic 110 transversalis . 405 | Fasciculi innominati ‘ 518 siliquee 426. 72 teretes 420. 528 | Fauces . . : INDEX. 635 Page Fage Femoral arch. 4 . 289 | Funiculi silique . 426. 429 canal . ‘ . 288 hernia . «> .« , 289 | Galeacapitis. .. eR - ring. : - 289 | Galen ‘ ‘ : . 292 Fenestra ovalis . ¥ . 511 | Gall-bladder : . 584 rotunda ‘ . 511 | Ganglia, cervical : - 485 Fibres of the heart . . 538 increase of . . 429 Fibrous cartilage . 114 lumbar ; . 489 inter-articular of the sacral , P - 490 clavicle . . 135, 136 semi-lunar . - 488 JW Ta Sti - 126 structure of . - 404 knee . : - 149 thoracic ‘ . 488 e wrist . ; - 141 | Ganglion of Andersch . . 448 _ Fibro-cellular tissue . » 28 Arnold’s : . 483 _ Fibrous tissue. ‘ - 115 azygos . ‘ . 490 Filum terminale : - 432 cardiac ; - 487 Fimbrie, Fallopian . . 611 carotid ‘ - 485 ‘Fissure of Bichat ‘ ~ 411 Casserian . . 439 Sylvius - 423 ciliary . . - 481 Fissures of the liver. . 575 Cloquet’s i . 482 OS ae ae . 421 impar) wicgseatl 4. 408 Feetal circulation : . 616 jugular ~« 448, 449 _ Feetus, anatomy of . . 616 lenticular. - 481 - Follicles of Lieberkuhn «> BED Meckel’s . 482 Fontana, notice of . . 497 naso-palatine . 482 Foramen, Botal, of . . 624 otic . q . 483 cecum 27. 426. 520 petrous 4 . 448 commune anterius 418 Ribes, of . -. 480 posterius 418 semi-lunar .. « 488 Monro, of . 416, 418 spheno-palatine . 482 ovale . . 616. 624 submaxillary - 484 saphenum . . 287 thyroid . e's Soemmering, of . 499 vertebral. . 486 : Winslow, of . 557 | Gimbernat’s ligament . » 212 Foramina Thebesii . . 533 | Ginglymus = ; . 110 Fornix . ‘ . 415 | Gland, epiglottic : - 548 Fossa fanctithate ‘ . 507 pineal . ot pees navicularis urethre . 601 pituitary . 424 pudendi . 613 _ prostate . ‘ - 595 ovalis : , . 534 thymus . : - 620 scaphoides ecm | thyroid . . 549. 620 Fourchette ‘ ; . 614 | Glands, aggregate , . iSF2 Freena epiglottidis . 519. 544 arytenoid . - 548 Frenulum labiorum . . 613 Brunner’s. 2 671 Frenum labii_ . 4 . 560 concatenate . . 3890 lingue . : . 519 Cowper’s : - 601 preeputii A « 692 duodenal F . 571 6 36 INDEX. GLANDS—continued. Page Page gastric . = 'w O71 | Helix white : . 506 inguinal ~ « 891 | Hepatic duct . : . $85 lachrymal . . 505 | Hernia, congenital . . 2819 Lieberkuhn’s. . 572 eer - 220 lymphatic . . 389 direct . . 281) mammary . . 614 encysted : - 281% mesenteric. . 3895 femoral , : . 289 Meibomian . * 504 infantilis ; . 3344 cesophageal . . $71 inguinal é . 280° Pacchionian . - 406 scrotal oh oe parotid . : . 561 | Highmore, notice of, . . 604 Peyer’s ; . 572 | Hilton’s muscle . ; . 546 pharyngeal . . 571 | Hilus lienis ‘ : . 586 salivary . ‘ - 561 renalis . : « 589 solitary. . . 571 | Hippocampusmajor . . 415 sublingual . - 562 minor . . 414 submaxillary . . 562 | Horner’s muscle 168 sudoriparous . - 528 | Houston, Mr., researches of, 569 tracheal : . 549 | Humours of the eye . - 501 Glandule odorifere . . 597 | Hyaloid membrane . . 501 Pacchioni . . 406 | Hymen . - 613 Tysoni : . 597 | Hypochondriac regions - 5540 Glans clitoridis . ‘ - 613 | Hypogastric region . - 554 penis . . ..« 597 | Hypophysis cerebri . - 424 Glisson, notice of, j - 580 Glisson’s capsule. . 578.580 | Ileo-cacal valve F . 569) Globus major epididymis . 603 | Tleum . ‘ ° - 566— minor epididymis . 603 | Iliac regions . ‘ - 540 Glomeruli . ‘ y . 590 | Ineus 4 : ‘ - 5d Glottis . ‘ - 547 | Infundibula , : . 590 Goodsir, Mr., esocirleil of,. 66 | Infundibulum . : . 4247 Goitre ‘ ’ - 549 | Inguinal region. . 554 Gomphosis Bree . 109 | Inter-articular cartilages, of the | Graafian vesicles i . 612 clavicle 135, 136 Gubernaculum testis . - 626 jaw. . 196 Gums Y . 560 wrist . . 1419 Guthrie, Mr., researches of, . 594 | Inter-columnar fibres . . 23) Guthrie’s muscle , . 222 | Inter-vertebral substance . 119° Gyrus fornicatus - « 415 | Intestinal canal ~. 565 - Intumescentia gangliformis . 445 — Hair ‘ - 526 | Iris . . . 498 — Halt, Dr. Marshall, researches 403 | Isthmus of the faxuces ; . 567) Harmonia . . 52.109 | Iter ad infundibulum. . 418° Haversian canals ; , 2 a tertio ad quartum ven- , Heart... xi 2-B80.588, 624 theihate 418 Helicine arteries 2 . §98 Helico-trema . : . 516 | Jacob’s membrane . 499 3 a ee ee ‘ INDEX, 637 Page Jejunum . ‘ ‘ - 566 Joint, ankle é J w: B58 elbow ‘ ‘ - 139 hip . 5 ; . 146 lower jaw : - 125 knee ; : ot ERP shoulder . P ee wrist : c . 141 Jones, Mr., researches of, . 517 Kidneys. é . 588. 625 Krause, researches of, . « 226 Labia majoras. ; . 612 a minora. , - 613 ~ Labyrinth ; 4 eas Lachrymal canals ; . 505 gland : . 505 papille . . 503 puncta - 503.505 sac. ; 506 - tubercles. . 503 Lacteals . . 888. 395 Lacune . : - 601 Lacus lachrymalis ‘ - 503 Lamina cinerea . ; . 423 cribrosa P - 495 spiralis 3 . 516 Laqueus . ‘ ; - 429 Laryngotomy . : - 544 Larynx . g . 541 Lateral ventricles ‘ ray 2p Lauth, researches of, . . 604 Lee, Dr., researches of, - 610 Lens i - 501 Lenticular ganglion ; - 481 Lieberkuhn’s follicles . - 672 Lien succenturiatus . ~. 586 Ligament . ‘ : - 115 LIGAMENTS ; - 109 aieaiiielavicular « ¥S6 alar ‘ ei RRS ABE ankle, of the . - 1538 annular, of the ankle 289 radius . . 140 wrist, anterior 143 posterior 286 LIGAMENTS—continued. Page arcuatum externum . 218 internum . 218 atlo-axoid ; . 124 bladder, of the, - 592 breve plante . . 156 caleaneo-astragaloid . 155 cuboid - 155 seaphoid . 155 capsular of the hip . 146 jaw - 126 rib 5) 28 shoulder 138 thumb . 144 carpal. . 142 carpo-metacarpal - 143 common anterior . 118 posterior . 119 conoid . ‘ wt Oe coracoid . ‘ a tee coraco-acromial ORE clavicular 2 EEG humeral oo Une coronary : - 140 of the knee. 149 costo-clavicular pe Fi sternal . “829 transverse > Saat vertebral . . 128 xyphoid . . 130 cotyloid : <. AE pri abc . 543 crucial . - 149 cruciform ° SEBS deltoid ‘i . 154 dentatum : . 432 elbow, of the, - « ¥39 epiglotto-hyoidean . 544 glenoid . » 138 glosso-epiglottic - 544 hip-joint, of the, . 146 hyo-epiglottic . 544 ilio-femoral . 146 inter-articular of phy 128 inter-clavicular - 135 inter-osseous calcaneo-astragaloid 156 peroneo-tibial . 152 638 INDEX. LiGAMENTS—continued. Page | LigAMENTS—continued. inter-osseous radio-ulnar 1 40 sub-pubic . inter-spinous . 120 supra-spinous . inter-transyerse 121 suspensorium hepatis inter-vertebral . 119 penis . knee, of the, . - aeT tarsal . lateral, of the ankle . 154 tarso-metatarsal elbow 139 teres . jaw: « - 125 thyro-arytenoid knee. 148 thyro-epiglottic . phalanges, foot 158 thyro-hyoidean . phalanges, = 145 tibio-fibular . . wrist 141 transverse liver, of the, 575 of the acetabulum . longum plantz 155 of the ankle lumbo-iliac 130 of the atlas . lumbo-sacral 130 of the knee . é metacarpal 145 of the metacarpus . metatarsal 156 of the metatarsus . mucosum 150 of the scapula nuchze 197 of. the semilunar oblique 140 cartilages obturator 134 trapezoid occipito-atloid . 12] tympanum, of the axoid . 123 umbilical odontoid 123 wrist, of the orbicular 140 Zinn, of palpebral 504 | Ligamentum nuchze patellze ; 148 | Limbus luteus peroneo-tibial . - 152 | Linea alba phalanges, of the foot 158 | Linez semi-lunares . of the hand 145 transverse 212. plantar, long . 155 | Linguetta laminosa ‘ plantar, short . 156 | Lips ; ‘ posticum Winslowii. 148 | Liquor Cotunnii 07 aurora rh 189 Morgagni pubic 134 Scarpa, of ; radio-ulnar 140 | Liver 574. 63 rhomboid 135 | Lobules of the liver ‘ rotundum, hepatis 575 | Lobuli testis sacro-coccygean 133 | Lobulus auris sacro-iliac 131 pneumogastricus sacro-ischiatic 131 | Lobus caudatus : stellate 128 quadratus ‘ . sternal 130 Spigelii sterno-clavicular 135 | Locus niger stylo-maxillary 277 perforatus sub-flava 120 | Lower, notice of Page Page Lumbar fascia. ‘ . 217 | Medulla of bones ‘ : 4 regions . : . 554 innominata . - 423 Lungs : < . 550. 623 oblongata. . 426 Lunula 525 | Meibomian glands’. - 504 Lymphatic glands and vessels 387 | Meibomius, notice of . . 504 axillary . . - 391 | Membranadentata . . 432 bronchial ; . 394 nictitans . - 505 cardiac . e .. = 304 pigmenti . - 497 cervical . - 390 pupillaris . - 620 head and neck - 389 sacciformis . 148 heart. ‘ . 394 tympani. - 508 iliac ‘ ; . 393 | Membrane, choroid . . 496 inguinal : . 391 hyaloid . - 601 intestines ‘ - 395 Jacob’s. - 499 kidney ; . 396 of the ventricles . 420 lacteals . - 9388. 395 | Membranous urethra . - 601 liver ‘ e . 394 | Meniscus . ‘ . 114 lower extremity . 391 | Mesenteric glands : . 3895 lungs. ; . 394 | Mesentery d ‘ . 558 mediastinal . - 3893 | Meso-cola : , - 558 mesenteric : . 395 | Meso-rectum . ‘ . 558 pelvic viscera . . 396 | Metacarpus da Pita ... vigth wg . 162 femoral. . . 471 Myopia . ; : . 503 fifth pair i . 438 first pair ‘ .* 435 - Naboth, ovula of ; . 609 fourth pair. . 438 Nagel, Mr., researches of, . 588 frontal . é . 439 Nails j ; , . 525 gastric . : . 452 Nares . . 61,491. 563 genito-crural . - 471 Nasal duct git . 506 glosso-pharyngeal . 447 fosse. - § 61. 493 gluteal . - 475 Nasmyth, Mr., researches of, 56 inferior - 476° Nates cerebri_. i . 418 gustatory. - 4435 NERVES, hypo-glossal . . 454 general anatomy . 399 ilio-scrotal . - 469 — INDEX. 643 NERVEs—continued. Page | NERVES—continued. Page inferior maxillary .- 442 plantar... - 478 infra-trochlear - 441 pneumo-gastric . 449 inguino-cutaneous . -470 popliteal deat ATT intercostal . 467 portio dura . . 445 intercosto-humeral . 468 mollis . . 447 inter-osseous anterior 463 pterygoid . - 443 posterior 466 pudendalis . . 476 ischiaticus major . 476 pudic internal - 475 minor . 476 pulmonary . .. 452 _ Jacobson’s. - 448 radial . ‘ - 465 lachrymal . . 439 recurrent. . 452 laryngeal inferior . 452 respiratory external 461 superior . 450 sacral . - 474 lingual . =... 454 saphenous extemal. 477 lumbar . ‘ . 468 long . 472 lumbo-sacral.. . 474 short . 472 masseteric . . 442 second pair . - 436 maxillaris inferior . 442 seventh pair . . 444 superior . 44] sixth pair. ~ 444 median . ° - 463 spheno-palatine . 482 molles . : - 486 spinal . ; - 455 motores oculorum . 437 spinal accessory . 452 - musculo-cutan. arm 461] splanchnic . . 488 leg 469. 479 stylo-hyoid . . 447 rousculo-spiral . 465 subcutaneus male . 44] mylo- aa . 444 sub-rufi : . 486 nasal. - 440 subscapular . - 461 naso-ciliaris . ©. 440 superficialis colli . 457 naso-palatine . . 482 cordis . 487 ninth pair. . 454 superior maxillary . 441 obturator. . 473 supra-orbital . . 439 occipitalis major . 459 scapular - 461 minor . 458 trochlear . 439 olfactory ‘ .- 435 sympatheticus major 480 ophthalmic . -~ 4389 minor 445 optic . ; . 436 temporal z - 442 orbital . ‘ - 441 temporo-facial. . 445 palatine ; - 482 malar . 441 palmar . . 464. 465 third pair. - 437 pathetici . . 438 thoracic . : - 460 perforans Casserii . 461 thyro-hyoidean . 455 perineal : . 476 tibialis anticus . 479 perineo-cutaneous . 476 posticus . 478 peroneal pier a MEO trifacial : . 438 petrosal . . 483. 484 trigeminus . . 438 pharyngeal . 449. 450 trochlearis . - 438 phrenic . ; . 458 tympanic . 446. 448 644 : INDEX. NERVES—continued, Page Page ulnar. , - 464 | Pelvis é é . 93. 592 vagus . 4 -. 449 viscera of . : - 592 vestibular . 447. 518 | Penis : ; ja. oy Vidian . ; . 483 | Pericardium ; . - 530 Wrisberg, of . - 463 | Perichondrium . . : 4 Neurilemma : . 401 | Pericranium . : J 40 Nipple. .. ‘ . 614 | Periosteum : ° : 40 Nodus encephal. é . 425 | Peritoneum é . - 5540 Nose . : : . 491 | Perspiratory ducts . . 529 Nucleus olive : . 427 | Pes accessorius . - ». 4isq Nymphe . : : - 613 | anserinus . : . 445 hippocampi . : . 415 (Esophagus ; . 564 | Petit, notice of . ° . 502 — Omentum, gastro-splenic . 558 | Peyer,moticeof. . . 572 great . ; . 558 | Peyer’s glands . ‘ . 572 lesser ; 557 | Phalanges . ‘ . 88. 107 Omphalo-mesenteric vessels. 624 Pharynx . . : - 563 — Optic commissure : . 437 | Pia mater . - 409. 432 thalami_ . . 413. 417 | Pigmentum nigrum ; . 497 Orbiculare, os. . + 510 | Pillars of the palate . - 561 — Orbits. > . 61 | Pineal gland. ° - 419 © Ossicula auditis . ; - 508 | Pinna . : - 506 Ossification ‘ : ; 5 | Pituitary gland . : - 424 Ostium abdominale_ . . eee membrane , ~ 493 © Ostium uterinum ‘ - 611 | Pleura. ; é . 552 Otoconites : . . 518 | Plexus, aortic . . . 489 Ovaries . - 611. 626 axillary . : . 459 Ovula Graafiana . . . 612 brachial . 5 . 4659 Naboth, of . . 609 cardiac . - 487 © carotid . : . 484 © Pacchionian glands. . 406 cavernous. . 484 — Palate : ‘ - 560. 561 cervical . : . 457 Palmar arch 4 . 331 choroid . : . 413 Palpebree . : ‘ . 503 .. celiac . ‘ . 489 Palpebral ligaments. - 504 coronary , - 488 sinuses , . 504 gangliformis . . 449 Pancreas . - 585 gastric . . . 489 Panizza, researches of . 485 hepatic . é . 489 Papille of the nail . . . 525 hypogastric . . 4899 of the skin . . 522 lumbar . ‘ . 469 of the tongue . . 520 mesenteric . . 489 — Papille calyciformes . . 520 cesophageal . - 452 circumvallate . . 520 pharyngeal . 449. 450 conics . , . 520 phrenic . : . 489 | filiformes ; . 520 prostatic é . 380 fungiformes . . 520 pterygoid ; . 3869 Parotid gland. ; . 56] pulmonary . . 452 Plexus, renal sacral _ solar ' . spermatic F splenic . : submaxillary . supra-renal . uterine . : F vertebral vesical . ° Plica semilunaris Plicze longitudinales Pneumogastric lobule . _ Polypus of the heart . Pomum Adami . ~ Pons Tarini _ Varolii Pores Portal vein Portio dura mollis Porus opticus Poupart’s sai _ Prepuce Presbyopia Processus e cerebello ad testes clavatus vermiformes . Promontory Prostate gland Prostatic urethra Protuberantia annularis Pulmonary. artery plexuses sinuses . veins Puncta Jachrymalia - vasculosa Punctum ossificationis Pupil Purkinje, corpuscles of Pylorus . . Pyramid Pyramids, anterior . Malpighi, of posterior 447, 569. 425, 386. 427. 364, 452. 386. 503. INDEX Page 489 | Raphé corporis callosi 470 | Receptaculum chyli 489 | Rectum 489 | Regions, abdominal 489 | Reil, island of 457 | Respiratory nerves . . 489 tract 380 | Rete mucosum . i 487 testis 380 | Retina : 505 | Ribes, ganglion of 611 | Rima glottidis 421 | Ring, external abdominal 531 femoral . 541 internal abdominal 424 | Rugee 431 | Ruysch, notice of 524 580 | Sacculus communis 445 laryngis 447 proprius 495 | Salivary glands . 212 | Saphenous opening 597 veins 503 | Scala tympani 422 vestibuli 433 | Scarf-skin . 421 | Scarpa, notice of g 511 | Schindylesis 53. 595 | Schneider, notice of ‘ 599 | Schneiderian membrane 425 | Sclerotic coat 552 | Scrotum. 552 | Searle, Mr., researches of, 536 | Sebaceous glands 552 | Semicircular canals. 505 | Semilunar-fibro-cartilages . 410 valves . 536. 5 | Septum auricularum 498 crurale . ‘ 2 lucidum . 415. 564 pectiniforme 512 scroti 426 | Serous membrane, structure . 589 | Sesamoid bones 420 | Sheath of the rectus Sigmoid valves 536. 645 Page 4)] 396 568 553 423 435 435 523 605 499 480 547 212 289 28 569 497 517 547 517 561 287 378 516 516 522 518 109 493. 493. 494 601 538. 527 514 149 538 533. 289 430 598 602 559 107 217 538. LL a ee ee ee eee ee 646. INDEX. ze Page ; Sinuses, structure 368 | Substantia perforata . , _Sints aortic 538 | Sudoriferous ducts . basilar 374 | Sudoriparous glands : cavernous . 372 | Supercilia . » Aine 5 circular 374 | Superficial fascia 4 fourth . 372 | Supra-renal capsules 587. 625 lateral . . 872 | Suspensory ligament, liver . longitudinal inferior . 372 penis . superior . 37! | Sutures 52. 109 occipital anterior 374 | Sylvius, notice of posterior 372 | Sympathetic system é petrosal inferior . 373 | Symphysis ; superior 374 | Synarthrosis . . pocularis .. 599 | Synovia . ° i prostatic . 599 Synovial membrane ‘. pulmonary 536 rectus or straight 372 | Tapetum ° 430. 497 rhomboidalis” 419 | Tarin, Peter, notice of, - 413 transverse . 374 | Tarsal saat «att beaise-tile of 536. 538 | Tarsus S ° » A Skeleton ‘ 9 | Teeth pots ie geet sae Skin . : . : 521 | Tendo Achillis . 266 Skull Sc crre ; 21 oculi » . 168 Socia parotidis . 562 | Tendon . . . 116 Soemmering, notice of . 499 | Tenia hippocampi 414. 415 - Soft palate . 561 semicircularis . . 413 Spermatic canal . 280 Tarini . . 4137 cord . 602 | Tentorium cerebelli . . 407 Spheno-maxillary ganglion . 482 | Testescerebri . . . 418° Spigel, notice of . 577 | Testicles . . « 601. 626 Spinal cord Marts 431 descent éuc. 3: ee nerves 455 | Thalami optici 413. 417 © veins 383 | Thebesius, notice of , 5339 Spleen. . 586 | Theca vertebralis 431 Spongy part of the utethoasc:: O02 | Thoracic @uct - 396 Stapes 510 | Thorax . 71. 530 Stenon, notice of 561 | Thymus gland . - 620 Stenon’s duct . : 561 | Thyro-hyoid membrane . 543 Stomach 564 | Thyroid axis . . 818] Striw, medullares 447 | Thyroid cartilage . d4l muscular r - 160 gland . 549. 620. Sub-arachnoidean fluid 409. 432 | Tod, Mr., researches of, . 4508 space 409.431 | Tongue . . . 519.560 tissue 409.431 | Tonsils . ‘ ‘ . 561° Sublingual gland 562 cerebelli . . 419,421) Submaxillary gland 562 | Torcular pik ses . 3/27 Substantia cinerea 402 | Trachea 548 - INDEX. Page Tractus motorius - 438 | Valve, ileo-czcal, opticus . - 437 mitral . spiralis - 515 pyloric ; respiratorius 435 rectum, of the . Tragus d : - 506 semi-lunar 536. Triangles of the neck . 182. 184 Tarin, of, Tricuspid valves . - 534 tricuspid . . ° Trigone yesicale - 595 Vieussens, of . ‘ Trochlearis . 171 | Valvulee conniventes . . Tuber cinereum . 424 | Varolius, notice of Tubercula quadrigemina 418 | Vasa efferentia Bras), Tuberculum Loweri 534 lactea < 388. _ Tubuli lactiferi . 614 lymphatica . seminiferi 604 pampiniformia ae uriniferi . 2 589 recta Tunica albuginea oculi 495 vasorum . testis 604 | Vasculum aberrans x erythroides 602 | Vasdeferens . 596. nervea 570 | VxINs - , Ruyschiana - 497 structure j vaginalis . - 603 angular . : oculi . 172 auricular ‘i ‘ ; vasculosa testis . 604 axillary 3 _ Tutamina oculi 503 azygos : : Tympanum ‘ 508 basilic . . : Tyrrell, Mr., researches of. 282 cardiac : Tyson’s glands « 597 cava inferior 381 superior . 379 Umbilical region . 554 cephalic : ; Urachus 593. 625 cerebellar é Ureter . ; - 590 cerebral . ; Urethra, female . 606 coronary 384 male .. 599 corporis striati B Uterus 607. 626 diploé ; Utriculus communis STO dorsalis penis . 380. Uvea . 498 dorsi-spinal Uvula cerebelli . F 419, 421 emulgent palati . 561 facial vesicee 595 femoral . frontal Vagina. 607 Galeni Vallecula . x 21 gastric i Valsalva, sinuses ‘of, 536. 538 hepatic 382. Valve, arachnoid . 420 iliac = \ Bauhini 569 innominate ; coronary . 533 intercostal superior . Eustachian | 533 jugular V EINS—continued. lumbar mastoid . ‘ maxillary internal median . “ basilic . cephalic medulli-spinal . meningo-rachidian mesenteric occipital ovarian profunda femoris prostatic pulmonary radial. renal yt. : salvatella saphenous spermatic » spinal splenic subclavian temporal temporo-maxillary Thebesii thyroid ulnar uterine vertebral vesical Velum interpositum medullare INDEX. Page 382 | Velum pendulum palati 369 | Venez comites : 369 Galeni . 377 -vorticosze 3 377 | Ventricles of the brain, 377 Cibo SERRE sh ; 383 fourth 383 lateral 384 third . 369 of the heart 382 of the larynx 371 | Vermiform processes . 378 | Vertebral aponeurosis . 580 column 378 | Veru montanum 380 | Vesicule seminales 386 | Vestibule 376 | Vestibulum vagine 882 | Vibrisse ‘ 376 | Vidius, Vidus, notice of 378 | Vieussens, notice of 382 | Villi : 383 | Vitreous humour: 385 | Vulva 377 | Wharton, notice ‘af 369 | Wharton’s duct . 869 | Willis, notice of . 533 | Wilson’s muscles 375 | Winslow, notice of 376 | Wrisberg, nerve of 381 375 | Zinn, notice of 380 | Zonula ciliaris 417 of Zinn . .. 419 | Zygoma THE END. LONDON ; " Printed by S. & J. 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