UNIVERSITY OF CALIFORNIA MEDICAL CENTER LIBRARY SAN FRANCISCO Medical Library Exchange: White Memorial Medical Library PRESENTED TO COLLEGE Or DENTIST!? TY Or ^ UWYERSITY BCICKCC a rcci MANUAL OF PRACTICAL ANATOMY BY THE LATE D. ]. CUNNINGHAM M.D. (EDIN. ET DUEL.), D.SC., LL.D. (ST. AND. ET GLAS.), D.C.L. (OXON.), F.R.S. LATE PROFESSOR OF ANATOMY IN THE UNIVERSITY OF EDINBURGH FIFTH EDfTION EDITED BY ARTHUR ROBINSON PROFESSOR OF ANATOMY JN THE UNIVERSITY OF EDINBURGH VOLUME FIRST SUPERIOR EXTREMITY; INFERIOR EXTREMITY; ABDOMEN WITH 255 ILLUSTRATIONS . NEW YORK WILLIAM WOOD AND COMPANY MDCCCCXII PREFACE TO FIFTH EDITION VL this the fifth edition of Professor Cunningham's Manual of Practical Anatomy — the first edition which has appeared since his death — the editor has attempted to retain the essential features of a book which is neither a text-book of anatomy nor a mere description of the methods to be adopted for the satisfactory dissection of the different regions of the body. In a sense it is a combination of the two which avoids minuteness of detail, in- dispensable in a text-book, whilst at the same time it endeavours to be a reliable guide for those who desire to obtain a knowledge and comprehension of human anatomy which will be of practical use in the ordinary course of their professional work. The present edition differs from those which have preceded it in two important respects. Some of the plans of dissection have been changed and the Basle anatomical nomenclature has been adopted throughout. In Vol. I. the plans of dissection which have been either entirely altered or greatly modified are those dealing with the dissections of the axilla, the abdomen and the pelvis, and the changes have been made with the object of bringing the methods of dissection more into line with the necessities of present-day operative procedure, that is, with the object of displaying the parts in a sequence which shall be introductory to the study of the anatomical details of clinical diagnosis and operative work. All the dissections described have been performed repeatedly and successfully, in the dissecting-rooms of the University of Edinburgh, by students dissecting the parts for the first time ; and the new figures illustrating the various stages of the dissection of the abdomen have been drawn from dissections made by students preparing, in the ordinary way, for their professional examination in anatomy. Other plans were tried before those which are described were finally adopted ; and I am greatly indebted to my first and second assistants, Dr. E. B. Jamieson and Mr. T. B. Johnston, and to Pro- fessor R. B. Thomson of the South African College, Capetown, formerly my second assistant, for their loyal help and valuable suggestions during the progress of the work. I am also indebted to Messrs. O. Blackley, S. J. Linzell, M. Barseghian, R. C. Rogers, and F. M. Halley, for the skilful help, so willingly given, in the preparation of the dissections from which new drawings have been made, and to Mr. J. T. Murray, for the drawings, which fully sustains the reputation he has gained as a delineator and interpreter of anatomical subjects. The reasons for the adoption of the Basle anatomical nomen- clature are mainly CtynPir^tto and chiefly, because it is more iv PREFACE TO FIFTH EDITION regular and definite than that hitherto in use, and, therefore, it tends to inculcate greater definiteness of idea and statement. Secondly, because it has been very generally adopted in Canada, Australia, and America, and will be adopted in the new anatomical department of the South African College. Therefore, if we in Great Britain and Ireland retain the old terms, it will not be long before students and graduates who have been educated in the British Colonies and America will have difficulty in understanding the terminology in use in this country, and the blame for the un- necessary confusion which will result will lie with those of us who refuse to adapt ourselves, and fail to encourage our students to adapt themselves, to changing conditions. It is not for a moment suggested that the Basle anatomical terminology is perfect, indeed in many respects it might easily be improved, but on the whole it is simpler, more definite, and more instructive than the old terminology, particularly for the beginner, to whom the old terms are unknown ; moreover, it uses only one designation for each structure and, therefore, avoids the superfluity of terms which is one of the great drawbacks of the older nomen- clature. Thus it presents several advantages, and its deficiencies can easily be remedied, with a minimum of trouble, by the altera- tion of a few terms ; for the main principles are sound and are easily applied to details which were not considered at the Basle congress. It is admitted that the adoption of the Basle nomenclature will, for a time, be a source of some trouble to medical men to whom the old terms are familiar, but the difficulty can be alleviated by the frequent repetition of the old term after the new, when the former differs considerably from the latter — a plan which has been adopted in this volume. To further facilitate the transition from the older to the newer terminology, the glossary of the more important terms, indicating the differences between the old and the new, which was introduced in the last edition, and for which my thanks are due to Mr. J. Keogh Murphy, has been retained, but whilst the old terms were placed first, and the new last, in the old edition, the position has been reversed in this. Our experience in Edinburgh, during the past two years, encourages the belief that under the system outlined above, and adopted in this volume, the transition from the old to the new terminology will be the source of very little trouble to the student, whilst it will excite his interest and lead him to appreciate the value of terms which themselves convey instruction in anatomy as contrasted with others which have only historical associations. ARTHUR ROBINSON. CONTENTS THE UPPER EXTREMITY. PAGE AXILLA, ....... i DISSECTION OF THE BACK, ..... 37 SHOULDER — SCAPULAR REGION, ..... 48 FRONT OF THE ARM, . . . . . .62 DORSUM OF THE ARM, ..... 83 SHOULDER-JOINT, ....... 88 FOREARM AND HAND, ...... 94 VOLAR SURFACE AND MEDIAL BORDER OF THE FOREARM, . 97 WRIST AND PALM, ..... .no DORSUM AND LATERAL BORDER OF THE FOREARM, . . 132 DORSAL ASPECT OF THE WRIST AND HAND, . . . 142 ARTICULATIONS, . . . . . .148 INFERIOR EXTREMITY. THE THIGH, ... 166 SUPERFICIAL DISSECTION, . . . . 169 DEEP DISSECTION OF THE THIGH, . . . . 180 MEDIAL SIDE OF THE THIGH, ..... 204 GLUIVEAL REGION, . . . . . . .215 POPLITEAL SPACE, ..... . 234 BACK OF THE THIGH, ...... 245 THE LEG, ........ 257 ANTERIOR CRURAL REGION AND DORSUM OF FOOT, . . 259 LATERAL CRURAL OR PERONEAL REGION, . . . 273 MEDIAL CRURAL REGION, ...... 275 POSTERIOR CRURAL REGION, ..... 276 v vi CONTENTS PAGE SOLE OF THE FOOT, ...... 289 ARTICULATIONS, . . . . . . .310 ABDOMEN. MALE PERINEUM, ....... 340 ANAL TRIANGLE, ....... 345 UROGENITAL TRIANGLE, ...... 349 FEMALE PERINEUM, . . . . . . 364 ANAL TRIANGLE, ....... 369 UROGENITAL TRIANGLE, ...... 369 ABDOMINAL WALL, ...... 376 LUMBAR TRIANGLE AND LUMBAR FASCIA, . . . 418 HERNIA, ........ 420 ABDOMINAL CAVITY, ...... 426 VESSELS ON THE POSTERIOR WALL OF THE ABDOMEN, . . 539 FASCIA AND MUSCLES ON THE POSTERIOR WALL OF THE ABDOMEN, ....... 547 NERVES ON THE POSTERIOR WALL OF THE ABDOMEN, . . 550 PELVIS, -555 MALE PELVIS, ....... 557 LIGAMENTS OF THE PELVIC ARTICULATIONS, . . . 612 THE FEMALE PELVIS, . . . . . .619 THE PELVIC BLOOD-VESSELS, ..... 646 THE VISCERAL NERVES OF THE PELVIS, .... 647 THE PELVIC DIAPHRAGM, ...... 650 INDEX ........ 651 A GLOSSARY OF THE INTERNATIONAL (B.N.A.) ANATOMICAL TERMINOLOGY GENERAL TERMS. TERMS INDICATING SITUATION AND DIRECTION. Longitudinalis Verticalis Anterior Posterior Ventral Dorsal Cranial Sagittal is Frontalis Longitudinal Vertical Anterior ~i Posterior / Ventral ^ Dorsal Cranial Caudal Superior Inferior Proximalis Caudal J Superior 1 Inferior J Proximal \ Distalis Distal F Sagittal Frontal Referring to the long axis of the body. f Referring to the position of the long \^ axis of the body in the erect posture. j Referring to the front and back of the ^ body or the limbs. {Referring to the anterior and posterior aspects, respectively, of the body, and to the flexor and extensor aspects of the limbs, respectively, r Referring to position nearer the head | or the tail end of the long axis. "j Used only in reference to parts of I the head, neck, or body, f Used in reference to the head, neck, and body. Equivalent to cranial I and caudal respectively, f Used only in reference to the limbs. Proximal nearer the attached end. I Distal nearer the free end. rUsed in reference to planes parallel I with the sagittal suture of the | skull, i.e. vertical antero-posterior I planes. (Used in reference to planes parallel with the coronal suture of the skull, I i.e. transverse vertical planes, vii Vlll GLOSSARY Horizontalis Medianus Medialis Lateralis Intermedius Superficialis Profundus Externus Internus Ulnaris Radialis Tibial Fibular Horizontal Median Medial Lateral Intermediate Superficial \ Deep J External \ Internal j Ulnar j Radial/ Tibial \ Fibular /Used in reference to planes at right \ angles to vertical planes. /Referring to the median vertical I antero-posterior plane of the body. i Referring to structures relatively nearer to or further away from the ( median plane. t Referring to structures situated be- tween more medial and more [ lateral structures. /Referring to structures nearer to and \ further away from the surface. Referring, with few exceptions, to the walls of cavities and hollow organs. 1 Not to be used as synonymous with I medial and lateral. (Used in reference to the medial and lateral borders of the forearm, respectively. j'Used in reference to the medial and J lateral borders of the leg, re- ( spectively. THE BONES. B.N.A. TERMINOLOGY. Vertebrae Fovea costalis superior Fovea costalis inferior Fovea costalis transversalis Radix arcus vertebrae Atlas Fovea dentis Epistropheus Dens Sternum Corpus sterni Processus xiphoideus Incisura jugularis Planum sternale Ossa Cranii. Os frontale Spina frontalis Processus zygomaticus Facies cerebralis Facies frontalis OLD TERMINOLOGY. Vertebras Incomplete facet for head of rib, upper Incomplete facet for head of rib, lower Facet for tubercle of the rib Pedicle Atlas Facet for odontoid process Axis Odontoid process Sternum Gladiolus Ensiform process Supra-sternal notch Anterior surface Bones of Skull. Frontal Nasal spine External angular process Internal surface Frontal surface GLOSSARY IX B.N.A. TERMINOLOGY. Os parietale Lineae temporales Sulcus transversus Sulcus sagittalis Os occipitale Canalis hypoglossi Foramen occipitale magnum Canalis condyloideus Sulcus transversus Sulcus sagittalis Clivus Linea nuchae suprema Linea nuchce superior Linea nuchae inferior Os sphenoidale Crista infratemporalis Sulcus chiasmatis Crista sphenoidalis Spina angularis Lamina medialis processus ptery- goidei Lamina lateralis processus ptery- goidei Canalis pterygoideus [Vidii] Fossa hypophyseos Sulcus caroticus Conchae sphenoidales Hamulus pterygoideus Canalis pharyngeus Tuberculum sellae Fissura orbitalis superior Os temporale Canalis facialis [Fallopii] Hiatus canalis facialis Vagina processus styloidei Incisura mastoidea Impressio trigemini Eminentia arcuata Sulcus sigmoideus Fissura petrotympanica Fossa mandibularis Semicanalis tubae auditivae Os ethmoidale Labyrinthus ethmoidalis Lamina papyracea Processus uncinatus OLD TERMINOLOGY. Parietal Temporal ridges Groove for lateral sinus Groove for sup. long, sinus Occipital Anterior condyloid foramen Foramen magnum Posterior condyloid foramen Groove for lateral sinus Groove for sup. long, sinus Median part of upper surface of basi occipital Highest curved line Superior curved line Inferior curved line Sphenoid Pterygoid ridge Optic groove Ethmoidal crest Spinous process Internal pterygoid plate External pterygoid plate Vidian canal Pituitary fossa Cavernous groove Sphenoidal turbinal bones Hamular process Pterygo-palatine canal Olivary eminence Sphenoidal fissure Temporal Bone Aqueduct of Fallopius Hiatus Fallopii Vaginal process of tympanic bone Digastric fossa Impression for Gasserian ganglion Eminence for sup. semicircular canal Fossa sigmoidea Glaserian fissure Glenoid cavity Eustachian tube Ethmoid Lateral mass Os planum Unciform process GLOSSARY B.N.A. TERMINOLOGY. Os lacrimale Hamulus lacrimalis Crista lacrimalis posterior Os nasale Sulcus ethmoidalis Maxilla Facies anterior Facies infra-temporalis Sinus maxillaris Processus frontal is Processus zygomaticus Canales alveolares Canalis naso-lacrimalis Os incisivum Foramen incisivum Os palatinum Pars perpendicularis Crista conchalis Crista ethmoidalis Pars horizontalis Os zygomaticum Processus temporalis Processus fronto-sphenoidalis Foramen zygomatico-orbitale Foramen zygomatico-faciale Mandibula Spina mentalis Linea obliqua Linea mylohyoidea Incisura mandibulse Foramen mandibulare Canalis mandibulse Protuberantia mentalis OLD TERMINOLOGY. Lachrymal Bone Hamular process Lachrymal crest Nasal Bone Groove for nasal nerve Superior Maxillary Bone Facial or external surface Zygomatic surface Antrum of Highmore Nasal process Malar process Posterior dental canals Lacrimal groove Premaxilla Anterior palatine foramen Palate Bone Vertical plate Inferior turbinate crest Superior turbinate crest Horizontal plate Malar Bone Zygomatic process Frontal process Tempora-malar canal Malar foramen Inferior Maxillary Bone Genial tubercle or spine External oblique line Internal oblique line Sigmoid notch Inferior dental foramen Inferior dental canal Mental process The Skull as a Whole. Ossa suturarum Foveolse granulares (Pacchioni) Fossa pterygo-palatina Canalis pterygo-palatinus Foramen lacerum Choanoe Fissura orbitalis superior Fissura orbitalis inferior Wormian bones Pacchionian depressions Spheno-maxillary fossa Posterior palatine canal Foramen lacerum medium Posterior nares Sphenoidal fissure Spheno-maxillary fissure GLOSSARY XI Upper Extremity. B.N.A. TERMINOLOGY. OLD TERMINOLOGY. Clavicula Clavicle Impression for conoid ligament Impression for rhomboid ligament Tuberositas coracoidea Tuberositas costalis Scapula Incisura scapularis Angulus lateralis Angulus medialis Humerus Sulcus intertubercularis Crista tuberculi majoris Crista tuberculi minoris Facies anterior medialis Facies anterior lateralis Margo medialis Margo lateralis Sulcus nervi radialis Capitulum Epicondylus medialis Epicondylus lateralis Ulna Incisura semilunaris Incisura radialis Crista interossea Facies dorsalis Facies volaris Facies medialis Margo dorsalis Margo volaris Radius Tuberositas radii Incisura ulnaris Crista interossea Facies dorsalis Facies volaris Facies lateralis Margo dorsalis Margo volaris Carpus Os naviculare Os lunatum Os triquetrum Os multangulum majus Os multangulum minus Os capitatum Os hamatum Scapula Supra-scapular notch Anterior or lateral angle Superior angle Humerus Bicipital groove External lip Internal lip Internal surface External surface Internal border External border Musculo-spiral groove Capitellum Internal condyle External condyle Ulna Greater sigmoid cavity Lesser sigmoid cavity External or interosseous border Posterior surface Anterior surface Internal surface Posterior border Anterior border Radius Bicipital tuberosity Sigmoid cavity Internal or interosseous border Posterior surface Anterior surface External surface Posterior border . Anterior border Carpus Scaphoid Semilunar Cuneiform Trapezium Trapezoid Os magnum Unciform Xll GLOSSARY Lower Extremity. B.N.A. TERMINOLOGY. Os coxae Linea glutsea anterior Linea glutsea posterior Linea terminalis Spina ischiadica Incisura ischiadica major Incisura ischiadica minor Tuberculum pubicum Ramus inferior oss. pubis Ramus superior oss. pubis Ramus superior ossis ischii Ramus inferior oss. ischii Pecten ossis pubis Facies symphyseos Pelvis Pelvis major Pelvis minor Apertura pelvis minoris superior Apertura pelvis minoris inferior Femur Fossa trochanterica Linea intertrochanterica Crista intertrochanterica Condylus medial is Condylus lateralis Epicondylus medialis Epicondylus lateralis Tibia Condylus medialis Condylus lateralis Eminentia intercondyloidea Tuberositas tibiae Malleolus medialis Fibula Malleolus lateralis OLD TERMINOLOGY. Innominate Bone Middle curved line Superior curved line Margin of inlet of true pelvis Spine of the iscbium Great sacro-sciatic notch Lesser sacro-sciatic notch Spine of pubis Descending ramus of pubis Ascending ramus of pubis Body of ischium Ramus of ischium Pubic part of ilio-pectineal line Symphysis pubis Pelvis False pelvis True pelvis Pelvic inlet Pelvic outlet Femur Digital fossa - Spiral line Post, intertrochanteric line Inner condyle Outer condyle Inner tuberosity Outer tuberosity Tibia Internal tuberosity External tuberosity Spine Tubercle Internal malleolus Fibula External malleolus Bones of the Foot. Talus Calcaneus Tuber calcanei Processus medialis tuberis calcanei Processus lateralis tuberis calcanei Os cuneiforme primum Os cuneiforme secundum Os cuneiforme tertium Astragalus Os calcis Tuberosity of Inner Outer Inner cuneiform Middle cuneiform Outer cuneiform GLOSSARY xiii THE LIGAMENTS. Ligaments of the Spine. B. N.A. TERMINOLOGY. OLD TERMINOLOGY. Lig. longitudinale anterius Anterior common ligament Lig. longitudinale posterius Posterior common ligament Lig. flava Ligamenta subflava Membrana tectoria Posterior occipito-axial ligament Articulatio atlanto-epistrophica Joint between the atlas and the axis Lig. alaria Odontoid or check ligaments Lig. apicis dentis Suspensory ligament The Ribs. Lig. capituli costae radiatum Anterior costo-vertebral or stellate ligament Lig. sterno-costale interarticulare Interarticular chondro-sternal liga- ment Lig. sterno-costalia radiata Anterior and posterior chondro- sternal ligament Lig. costoxiphoidea Chondro-xiphoid ligaments The Jaw. Lig. temporo-mandibulare External lateral ligament of the jaw Lig. spheno-mandibulare Internal lateral ligament of the jaw Lig. stylo-mandibulare Stylo-maxillary ligament Upper Extremity. Lig. costo-claviculare Rhomboid ligament Labrum' glenoidale Glenoid ligament Articulatio radio-ulnaris proximalis Superior radio-ulnar joint Lig. collaterale ulnare Internal lateral ligament of elbow- joint Lig. collaterale radiale External lateral ligament Lig. annulare radii Orbicular ligament Chorda obliqua Oblique ligament of ulna Articulatio radio-ulnaris distalis Inferior radio-ulnar joint Discus articularis Triangular fibro-cartilage Recessus sacciformis Membrana sacciformis Lig. radio-carpeum volare Anterior ligament of the radio- carpal joint Lig. radio-carpeum dorsale Posterior ligament of the radio- carpal joint Lig. collaterale carpi ulnare Internal lateral ligament of the wrist joint VOL. I — b XIV GLOSSARY B.N.A. TERMINOLOGY. Lig. collaterale carpi radiale Articulationes intercarpae Lig. accessoria volaria Lig. capitulorum (oss. metacar- palium) transversa Lig. collateralia OLD TERMINOLOGY. External lateral ligament of the wrist joint Carpal joints Palmar ligaments of the metacarpo- phalangeal joints Transverse metacarpal ligament Lateral phalangeal ligaments The Lower Extremity. Lig. arcuatum Lig. sacro-tuberosum Processus falciformis Lig. sacro-spinosum Labrum glenoidale Zona orbicularis Ligamentum iliofemorale Lig. ischio-capsulare Lig. pubo-capsulare Lig. popliteum obliquum Lig. collaterale fibulare Lig. collaterale tibiale Lig. popliteum arcuatum Meniscus lateralis Meniscus medialis Plica synovialis patellaris Plicae alares Articulatio tibio-fibularis Lig. capituli fibulae Syndesmosis tibio-fibularis Lig. deltoideum Lig. talo.-fibulare anterius Lig. talo-fibulare posterius Lig. calcaneo- fibulare Lig. talo-calcaneum laterale Lig. talo-calcaneum mediale Lig. calcaneo-naviculare plantare Lig. talo-naviculare Pars calcaneo-navicularis "| lig. [-bifur- Pars calcaneo-cuboidea J catum Subpubic ligament Great sacro-sciatic ligament Falciform process Small sacro-sciatic ligament Cotyloid ligament Zonular band Y-shaped ligament Ischio-capsular band Pubo-femoral ligament Ligament of Winslow Long external lateral ligament Internal lateral ligament Arcuate popliteal ligament P'xternal semilunar cartilage Internal semilunar cartilage Lig. mucosum Ligamenta alaria Superior tibio-fibular articulation Anterior and posterior superior 'tibio-fibular ligaments Inferior tibio-fibular articulation Internal lateral ligament of ankle Anterior fasciculus of external lateral ligament Posterior fasciculus of external lateral ligament Middle fasciculus of external lateral ligament External calcaneo-astragaloid liga- ment Internal calcaneo-astragaloid liga- ment Inferior calcaneo-navicular ligament Astragalo-scaphoid ligament Superior calcaneo -scaphoid liga- ment Internal calcaneo-cuboid ligament GLOSSARY xv THE MUSCLES. Muscles of the Back. Superficial. B.N.A. TERMINOLOGY. Levator scapulae OLD TERMINOLOGY. Levator anguli scapulas Muscles of the Chest. Serratus anterior Serratus magnus Muscles of Upper Extremity. Biceps brachii Lacertus fibrosus Brachialis Triceps brachii Caput mediale Caput laterale Pronator teres Caput ulnare Brachio-radialis Supinator Extensor carpi radialis longus Extensor carpi radialis brevis Extensor indicis proprius Extensor digiti quinti proprius Abductor pollicis longus Abductor pollicis brevis Extensor pollicis brevis Extensor pollicis longus Lig. carpi trans versum Lig. carpi dorsale Biceps Bicipital fascia , Brachialis anticus Triceps Inner head Outer head Pronator radii teres Coronoid head Supinator longus Supinator brevis Extensor carpi radialis longior Extensor carpi radialis brevior Extensor indicis Extensor minimi digiti Extensor ossis metacarpi pollicis Abductor pollicis Extensor primi internodii pollicis Extensor secundi internodii pollicis Anterior annular ligament Posterior annular ligament Muscles of Lower Extremity. Tensor fasciae latae Canalis adductorius (Hunteri) Trigonum femorale (fossa Scarpae major) Canalis femoralis Annulus femoralis M. quadriceps femoris — Rectus femoris Vastus lateralis Vastus intermedius Vastus medialis M. articularis genu Tibialis anterior Tensor fasciae femoris Hunter's canal Scarpa's triangle Crural canal Crural ring Quadriceps — Rectus femoris Vastus externus Crureus Vastus internus Subcrureus Tibialis anticus xvi GLOSSARY B.N.A. TERMINOLOGY. OLD TERMINOLOGY. Tendo calcaneus Tendo AchilHs Tibialis posterior Tibialis posticus Quadratus plantse Accessorius Lig. transversum cruris Upper anterior annular ligament Lig. cruciatum cruris Lower anterior annular ligament Lig. laciniatum Internal annular ligament Retinaculum musculorum pero- "\ nseorum superius r> 4.- i , r External annular ligament Retinaculum musculorum pero- j naeorum inferius Axial Muscles. Muscles of the Back. Serratus posterior superior Serratus posticus superior Serratus posterior inferior Serratus posticus inferior Splenius cervicis Splenius colli Sacro-spinalis Erector spinse Ilio-costalis— Ilio-costalis — Lumborum Sacro-lumbalis Dorsi Accessorius Cervicis Cervicalis ascendens Longissimus — Longissimus — Dorsi Dorsi Cervicis Transversalis cervicis Capitis Trachelo-mastoid Spinalis — Spinalis — Dorsi Dorsi Cervicis Colli Capitis Capitis Semispinalis — Semispinalis — Dorsi Dorsi Cervicis Colli Capitis Complexus Multifidus Multifidus spinre Muscles of Head and Neck. Epicranius Occipito-frontalis Galea aponeurotica Epicranial aponeurosis Procerus Pyramidalis nasi Pars transversa (nasalis) Compressor naris Pars alaris (nasalis) Dilatores naris Auricularis anterior Attrahens aurem Auricularis posterior Retrahens aurem Auricularis superior Attollens aurem Orbicularis oculi Orbicularis palpebrarum Pars lacrimalis Tensor tarsi GLOSSARY xvii B.N.A. TERMINOLOGY. OLD TERMINOLOGY. Triangularis Depressor anguli oris Quadratus labii superioris — Caput zygomaticum Zygomaticus minor Caput -infraorbitale Levator labii superioris Caput angulare Levator labii superioris alreque nasi Zygomaticus Zygomaticus major Caninus Levator anguli oris Quadratus labii inferioris Depressor labii inferioris Mentalis Levator menti Platysma Platysma myoides Sterno-thyreoid Sterno-thyroid Thyreo-hyoid Thyro-hyoid Muscles and Fascia of the Orbit. Fascia bulbi Capsule of Tenon Septum orbitale Palpebral ligaments Rectus lateralis Rectus externus Rectus medialis Rectus internus Muscles of the Tongue. Genio-glossus Genio-hyo-glossus Longitudinalis superior Superior lingualis Longitudinalis inferior Inferior lingualis Transversus linguoe Transverse fibres Verticalis linguae Vertical fibres Muscles of the Pharynx. Pharyngo-palatinus Palato-pharyngeus M. uvuke Azygos uvulae Levator veli palatini Levator palati Tensor veli palatini Tensor palati Glosso-palatinus Palato-glossus Deep Lateral Muscles of Neck. Scalenus anterior Scalenus anticus Scalenus posterior Scalenus posticus Longus capitis Rectus capitis anticus major Rectus capitis anterior Rectus capitis anticus minor Muscles of Thorax. Transversus thoracis Triangularis sterni Diaphragma pars lumbalis Diaphragm, lumbar part — Crus mediale "| ^ , . . c „ ,. Crura and origins trom arcuate Crus intermedium \ ligaments Crus laterale } Arcus lumbo - costalis medialis Ligamentum arcuatum internum (Halleri) Arcus lumbo - costalis lateralis Ligamentum arcuatum externum (Halleri) XV111 GLOSSARY Muscles of the Abdomen. B. N.A. TERMINOLOGY. Ligamentum inguinale (Pouparti) Ligamenlum lacunare (Gimbernati) Fibrse intercrurales Ligamentum inguinale reflexum (Collesi) Annulus inguinalis subcutaneus Crus superius Crus inferius Falx aponeurotica inguinalis M. transversus abdominis Linea semicircularis (Douglasi) Annulus inguinalis abdominalis OLD TERMINOLOGY. Poupart's ligament Gimbernat's ligament Intercolumnar fibres Triangular fascia External abdominal ring Internal pillar External pillar Conjoined tendon Transversalis muscle Fold of Douglas Internal abdominal ring Perineum and Pelvis. Transversus perinei superficialis M. sphincter urethrse membranaceas Diaphragma urogenitale Fascia diaphragmatis urogenitalis superior Fascia diaphragmatis urogenitalis inferior Arcus tendineus fasciae pelvis Ligamenta puboprostatica Fascia diaphragmatis pelvis superior Fascia diaphragmatis pelvis inferior Transversus perinei Compressor urethrse Deep transverse muscle and sphinc- ter urethrae Deep layer of triangular ligament Superficial layer of the triangular ligament White line of pelvis Anterior and lateral true ligaments of bladder Visceral layer of pelvic fascia Anal fascia THE NERVOUS SYSTEM. Spinal Cord. Fasciculus anterior proprius (Flech- sig) Fasciculus lateralis proprius Nucleus dorsalis Pars thoracalis Sulcus intermedius posterior Columnse anteriores, etc. Fasciculus cerebro-spinalis anterior Fasciculus cerebro-spinalis lateralis (pyramidalis) Fasciculus cerebello-spinalis Fasciculus antero - lateralis super- ficialis Anterior ground or basis bundle Lateral ground bundle Clarke's column Dorsal part of spinal cord Paramedian furrow Anterior grey column Direct pyramidal tract Crossed pyramidal tract Direct cerebellar tract Gowers' tract GLOSSARY xix > .b cS pfl le primary vesicle, ic thalamus). (geniculate bodies oineal body). (subthalamic regie pophysis). *Si3 a, I £ w - — - 2 w C/5 5 >^ £_ .2 B -Si n 1 1 5 -^ r— - rt S & 1 £ en 3 S J3 3 0 ^j oS £ O ^ ^_» ft "S ^ 1> *p, >^ S g .^ i •1 HX 1 S W x]X ^o A "o 1 C U T3 CO <-M | M-i O > J3 ri-( Ql f/5 H £ (U & S "o "o x '5 g c , — , cr f o ^ 1 o (5 a i ti "S <" cS 0 > £H U ^^ ^ >S"^ oS 2 S « •s s 2 c S o o .0 'S .2 ts .1 J3 ^ S o * S *• "rt S <3 to £ 0< O< 0 0 \L/ ^ g Q -— ^ "o II rj s a c la 1 1 1 O !l ii ^3 rt I ^c" rs Diencepha (inter-bra 1 Telenceph .S 5J"1 Q-I *fl r— 0 (U -, D ^ < h 1 .s .S3 II S E 5 J3 fl ta» s ) i o o H ! P 1*2. cr^ i 1 ! 1 a H II ^_ __^~—" . c 4 o s IB i S' M 'ee 0 (4 S § 0 1 XX GLOSSARY Brain. B.N.A. TERMINOLOGY. Khombencephalon Eminentia medialis Ala cinerea Ala acustica Nucleus nervi abducentis Nuclei n. acustici Fasciculus longitudinalis medialis Corpus trapezoideum Incisura cerebelli anterior Incisura cerebelli posterior Sulcus horizontalis cerebelli Lobulus centralis Folium vermis Tuber vermis Lobulus quadrangularis Brachium conjunctivum cerebelli Lobulus semilunaris superior Lobulus semilunaris inferior Cerebrum Pedunculus cerebri Colliculus superior Colliculus inferior Aqueductus cerebri Foramen interventriculare Hypothalamus Sulcus hypothalamicus Massa intermedia Fasciculus thalamo-mammillaris Pars opercularis Thalamus Pallium Gyri transitivi Fissura cerebri lateralis Gyrus temporalis superior Gyrus temporalis medius Gyrus temporalis inferior Sulcus centralis (Rolandi) Sulcus temporalis superior Sulcus temporalis medius Sulcus circularis Sulcus temporalis inferior Gyrus fusiformis Sulcus interparietalis Sulcus corporis callosi Sulcus cinguli Fissura hippocampi Gyrus cinguli OLD TERMINOLOGY. Eminentia teres Trigonum vagi Trigonum acusticum Nucleus of 6th nerve Auditory nucleus Posterior longitudinal bundle Corpus trapezoides Semilunar notch (of cerebellum) Marsupial notch Great horizontal fissure Lobus centralis Folium cacuminis Tuber valvulae Quadrate lobule Superior cerebellar peduncle Postero-superior lobule Postero-inferior lobule Crus cerebri Anterior corpus quadrigeminum Posterior corpus quadrigeminum Iter e tertio ad quartum ventri- culum, or aqued. of Sylvius Foramen of Monro Subthalmic region Sulcus of Monro Middle commissure Bundle of Vicq d'Azyr Pars basilaris Optic thalamus Cortex cerebri Annectant gyri Fissure of Sylvius First temporal gyrus Second temporal gyrus Third temporal gyrus Fissure of Rolando Parallel sulcus Second temporal sulcus Limiting sulcus of Reil Occipito-temporal sulcus Occipito-temporal convolution Intraparietal sulcus Callosal sulcus Calloso-marginal fissure Dentate fissure Callosal convolution GLOSSARY xxi B.N.A. TERMINOLOGY. Stria terminalis Trigonum collaterale Hippocampus Digitationes hippocampi Fascia dentata hippocampi Columna fornicis Septum pellucidum Inferior cornu Commissura hippocampi Nucleus lentiformis Pars frontalis capsulae internse Pars occipitalis capsulae internse Radiatio occipito-thalamica Radiatio corporis callosi Pars frontalis Pars occipitalis OLD TERMINOLOGY. Tsenia semicircularis Trigonum ventriculi Hippocampus major Pes hippocampi Gyrus dentatus Anterior pillar of fornix Septum lucidum Descending horn of lateral ventricle Lyra Lenticular nucleus Anterior limb (of internal capsule) Posterior limb (of in ternal capsule ) Optic radiation Radiation of corpus callosum Forceps minor Forceps major Membranes of Brain. Cisterna cerebello-medullaris Cisterna interpeduncularis Granulationes arachnoideales Tela chorioidea ventriculi tertii Tela chorioidea ventriculi quarti Cisterna magna Cisterna basalis Pacchionian bodies Velum interpositum Tela choroidea inferior Cranial Nerves. N. oculomotorius N. trochlearis N. trigeminus Ganglion semilunare (Gasseri) N. naso-ciliaris N. maxillaris N. meningeus (medius) N. zygomaticus Rami alveolares superiores pos- teriores Rami alveolares superiores medii Rami alveolares superiores an- teriores Ganglion spheno-palatinum N. palatinus medius N. mandibularis Nervus spinosus N. alveolaris inferior N. abducens N. facialis N. intermedius N. acusticus Third nerve Fourth nerve Fifth nerve Gasserian ganglion Nasal nerve Superior maxillary nerve Recurrent meningeal nerve Temporo-malar nerve Posterior superior dental Middle superior dental Anterior superior dental Meckel's ganglion External palatine nerve Inferior maxillary nerve Recurrent nerve Inferior dental Sixth nerve Seventh nerve Pars intermedia of Wrisberg Eighth or auditory nerve XXII GLOSSARY B.N.A. TERMINOLOGY. Ganglion superius N. recurrens Ganglion jugulare Ganglion nodosum Plexus oesophageus anterior 1 Plexus oesophageus posterior J Nervus accessorius Ramus internus Ramus externus OLD TERMINOLOGY. Jugular ganglion of gth nerve Recurrent laryngeal nerve Ganglion of root 1 Ganglion of trunk jofva£us Plexus guise Spinal accessory Accessory portion of spinal accessory nerve Spinal portion Spinal Nerves. Rami posteriores Rami anteriores N. cutaneus colli Nn. supraclaviculares anteriores Nn. supraclaviculares medii Nn. supraclaviculares posteriores N. dorsalis scapulae Nn. intercosto-brachiales N. thoracalis longus N. thoraco-dorsalis N. cutaneus brachii medialis N. cutaneus brachii lateralis Fasciculus lateralis Fasciculus medialis N. cutaneus antibrachii lateralis N. cutaneus antibrachii medialis Ramus volaris Ramus ulnaris N. cutaneus antibrachii dorsalis N. axillaris N. interosseus volaris Ramus palmaris N. mediani Nn. digitales volares proprii Ramus dorsalis manus Ramus cutaneus palmaris N. radialis N. cutaneus brachii posterior N. cutaneus antibrachii dorsalis Posterior primary divisions Anterior primary divisions Superficial cervical nerve Suprasternal nerves Supraclavicular nerves Supra-acromial nerves Nerve to the rhomboids Intercosto-humeral nerve Nerve of Bell Long subscapular nerve Lesser internal cutaneous nerve Cutaneous branch of circumflex nerve Outer cord (of plexus) Inner cord Cutaneous branch of musculo-cuta- neous nerve Internal cutaneous nerve Anterior branch Posterior branch External cutaneous branch of mus- culo-spiral Circumflex nerve Anterior interosseous Palmar cutaneous branch of the median nerve Collateral palmar digital branches of median nerve Dorsal cutaneous branch of ulnar nerve Palmar cutaneous branch of ulnar nerve Musculo-spiral nerve Internal cutaneous branch of musculo-spiral nerve External cutaneous branches of musculo-spiral nerve GLOSSARY XXlll B.N.A. TERMINOLOGY. Ramus superficialis N. interosseus dorsalis Nn. digitales dorsales N. ilio-hypogastricus Ramus cutaneus lateralis Ramus cutaneus anterior N. genito-femoralis N. lumbo-inguinalis N. spermaticus externus N. cutaneus femoris lateralis N. femoralis N. saphenus Ramus infrapatellaris N. ischiadicus N. peronseus communis Ramus anastomoticus pero- naeus N. peronseus superficialis N. peronaeus profundus N. tibialis N. cutaneus surae medialis N. suralis N. plantaris medialis N. plantaris lateralis N. pudendus OLD TERMINOLOGY. Radial nerve Posterior interosseous nerve Dorsal digital nerves Ilio-hypogastric nerve Iliac branch of ilio-hypogastric nerve Hypogastric branch of ilio- hypogastric nerve Genito-crural nerve Crural branch of genito-crural nerve Genital branch of genito-crural nerve External cutaneous nerve Anterior crural nerve Long saphenous nerve Patellar branch of long saph- enous nerve Great sciatic nerve External popliteal nerve Nervus communicans fibularis Musculo-cutaneous nerve Anterior tibial nerve Internal popliteal nerve Nervus communicans tibialis Short saphenous nerve Internal plantar External plantar Pudic nerve THE HEART AND BLOOD-VESSELS. Heart. Atrium Auricula cordis Incisura cordis Trabeculae carnese Tuberculum intervenosum Sulcus longitudinalis anterior Sulcus coronarius Limbus fossae ovalis Valvula venae cavae Valvula sinus coronarii Auricle Auricular appendix Notch at apex of heart Columnae carnese Intervenous tubercle of Lower Anterior interventricular groove Auriculo- ventricular groove Annulus ovalis Eustachian valve Valve of Thebesius XXIV GLOSSARY Arteries. B.N.A. TERMINOLOGY. Sinus aortae A. profunda linguae A. maxillaris externa A. alveolaris inferior Ramus meningeus accessorius A. buccinatoria A. alveolaris superior posterior Aa. alveolares superiores anteriores Ramus carotico-tympanicus A. chorioidea A. auditiva interna Rami ad pontem A. pericardiaco-phrenica Rami intercostales ' Truncus thyreo-cervicalis A. transversa scapulas A. intercostalis suprema A. transversa colli A. thoracalis suprema A. thoraco-acromialis A. thoracalis lateralis A. circumflexa scapulae A. profunda brachii A. collateralis radialis A. collateralis ulnaris superior A. collateralis ulnaris inferior Ramus carpeus volaris Ramus carpeus dorsalis Aa. metacarpese dorsales A. volaris indicis radialis Arcus volaris superficialis Arcus volaris profundus A. interossea dorsalis A. interossea recurrens A. interossea volaris Ramus carpeus dorsalis Ramus carpeus volaris Aa. digitales volares communes Aa. digitales volares propriae Arteriae intestinales A. suprarenalis media A. hypogastrica A. umbilicalis A. pudenda interna A. epigastrica inferior OLD TERMINOLOGY. Sinuses of Valsalva Ranine artery Facial artery Inferior dental artery Small meningeal artery Buccal artery Posterior dental artery Anterior superior dental arteries Tympanic branch of int. carotid Anterior choroidal artery Auditory artery Transverse arteries (branches of Basilar artery) Arteria comes nervi phrenici Anterior intercostal arteries Thyroid axis Suprascapular artery Superior intercostal Transversalis colli Superior thoracic artery Acromio-thoracic artery Long thoracic artery Dorsalis scapulae Superior profunda Anterior branch of superior pro- funda Inferior profunda Anastomotica magna Anterior radial carpal Posterior radial carpal Dorsal interosseous arteries Radialis indicis Superficial palmar arch Deep palmar arch Posterior interosseous artery Posterior interosseous recurrent artery Anterior interosseous artery Posterior ulnar carpal Anterior ulnar carpal Palmar digital arteries Collateral digital arteries Intestinal branches of sup. mesen- teric Middle capsular artery Internal iliac artery Obliterated hypogastric Internal pudic artery Deep epigastric artery GLOSSARY XXV B.N.A. TERMINOLOGY. A. spermatica externa Aa. pudendae externse A. circumflexa femoris medialis A. circumflexa femoris lateralis A. genu suprema A. genu superior lateralis A. genu superior medialis A. genu media A. genu inferior lateralis A. genu inferior medialis A. malleolaris anterior lateralis A. malleolaris anterior medialis A. peronaea Ramus perforans A. malleolaris posterior lateralis A. malleolaris posterior medialis Kami calcanei laterales Kami calcanei mediales A. plantaris medialis A. plantaris lateralis Aa. metatarsese plantares Aa. digitales plantares OLD TERMINOLOGY. Cremasteric artery Superficial and deep external pudic arteries Internal circumflex artery External circumflex artery Anastomotica magna Superior external articular artery Superior internal articular artery Azygos articular artery Inferior external articular artery Inferior internal articular artery External malleolar artery Internal malleolar artery Peroneal artery Anterior peroneal artery Posterior peroneal artery Internal malleolar artery External calcanean artery Internal calcanean artery Internal plantar artery External plantar artery Digital branches Collateral digital branches Veins. V. cordis magna V. obliqua atrii sinistri Lig. venae cavae sinistrae Vv. cordis minimae Sinus transversus Confluens sinuum Plexus basilaris Sinus sagittalis superior Sinus sagittalis inferior Spheno-parietal sinus V. cerebri internae V. cerebri magna V. terminalis V. basalis V. transversa scapulae V. thoraco-acromialis Vv. transversae colli V. thoracalis lateralis V. azygos V. hemiazygos V. hemiazygos accessoria V. hypogastrica V. epigastrica inferior V. saphena magna V. saphena parva Great cardiac vein Oblique vein of Marshall Vestigial fold of Marshall Veins of Thebesius Lateral sinus Torcular Herophili Basilar sinus Superior longitudinal sinus Inferior longitudinal sinus Sinus alae parvae Veins of Galen Vena magna Galeni Vein of the corpus striatum Basilar vein Suprascapular vein Acromio-thoracic vein Transversalis colli veins Long thoracic vein Vena azygos major Vena azygos minor inferior Vena azygos minor superior Internal iliac vein Deep epigastric vein Internal saphenous vein External saphenous vein xxvi GLOSSARY Lymphatics. B.N.A. TERMINOLOGY. OLD TERMINOLOGY. Cisterna chyli Receptaculum chyli THE VISCERA. Digestive Apparatus. Arcus glosso-palatinus Anterior pillar of fauces Arcus pharyngo-palatinus Posterior pillar of fauces Gl. lingualis anterior Gland of Nuhn Ductus submaxillaris Wharton's duct Gl. parotis accessoria Socia parotidis Ductus parotideus (Stenonis) Stenson's duct Dentes prsemolares Bicuspid teeth Dens serotinus Wisdom tooth Papillae vallatse Circumvallate papillae Recessus pharyngeus Lateral recess of pharynx Tela submucosa Pharyngeal aponeurosis Plicae circulares Valvulse conniventes Gl. intestinales Crypts of Lieberkuhn Valvula coli Ileo-caecal valve Columnae rectales Columns of Morgagni Plicae transversales recti Valves of Houston Valvula spiralis Valves of Heister Noduli lymphatici aggregati Peyer's patches (Peyeri) Intestinum jejunum Jejunum Intestinum ileum Ileum Noduli lymphatici lienales Malpighian corpuscles (Malpighii) Respiratory Apparatus. Larynx Prominentia laryngea Adam's apple Incisura thyreoidea superior Superior thyroid notch M. ary-epiglotticus Aryteno-epiglottidean muscle M. vocalis Internal thyro-arytenoid muscle M. thyreo-epiglotticus Thyro-epiglottidean muscle Appendix ventriculi laryngis Laryngeal sac Plica vocalis True vocal cord Plica ventricularis False vocal cord Ligamentum ventriculare Superior thyro-arytenoid ligament Ligamentum vocale Inferior thyro-arytenoid ligament Glottis Glottis vera Rima vestibuli Glottis spuria Cartilage thyreoidea Thyroid cartilage GLOSSARY XXVll B.N.A. TERMINOLOGY. Membrana hyo-thyreoidea Cartilage corniculata (Santorini) Tuberculum epiglotticum Pars intermembranacea (rimse glottidis) Pars intercartilaginea (rimoe glottidis) Conus elasticus (membranoe elasticse larynges) Glandula thyreoidea- Glomus caroticum Nose Concha nasalis suprema (Santorini) Concha nasalis superior Concha nasalis media Concha nasalis inferior OLD TERMINOLOGY. Thyro-hyoid membrane Cartilage of Santorini Cushion of epiglottis Glottis vocalis Glottis respiratoria Crico-thyroid membrane Thyroid gland Intercarotid gland or body Highest turbinate bone Superior turbinate bone Middle turbinate bone Inferior turbinate bone Urogenital Apparatus. Corpuscula renis Paradidymis Appendix testis Ductus deferens Gl. urethrales Glandula bulbo-urethralis (Cowperi) Folliculi oophori vesiculosi Cumulus oophorus Tuba uterina Epoophoron Appendices vesiculosi Ductus epoophori longitudinalis Orificium internum uteri Orificium externum Processus vaginalis Glandula magna vestibuli Malpighian corpuscles Organ of Giraldes Hydatid of Morgagni (male) Vas deferens Glands of Littre Cowper's gland Graafian follicles Discus proligerus Fallopian tube Parovarium Hydatids of Morgagni (female) Gartner's duct Internal os (of uterus) External os Canal of Nuck Bartholin's gland Peritoneum. Bursa omentalis Foramen epiploicum Lig. phrenico-colicum Excavatio recto-uterina (cavum Douglasi) Lig. gastro-lienale Lesser peritoneal sac Foramen of Winslow Costo-colic ligament Pouch of Douglas Gastro-splenic omentum SENSE ORGANS. The Eye. Sclera Lamina elastica anterior (Bowmani) Sclerotic coat Bowman's membrane XXV111 GLOSSARY B.N.A. TERMINOLOGY. Lamina elastica posterior (Des- cemeti) Spatia anguli iridis Angulus iridis Zonula ciliaris Septum orbitale Fascia bulbi Commissura palpebrarum lateralis Commissura palpebrarum medialis Tarsus superior Tarsus inferior Lig. palpebrale mediale Raphe palpebralis lateralis Tarsal glands OLD TERMINOLOGY. Descemet's membrane Spaces of Fontana Irido-corneal junction Zonule of Zinn Palpebral ligament Capsule of Tenon External canthus Internal canthus Superior tarsal plate Inferior tarsal plate Internal tarsal ligament External tarsal ligament Meibomian glands The Ear. Canalis semicircularis lateralis Ductus reuniens Ductus cochlearis Recessus sphericus Recessus ellipticus Paries jugularis Paries labyrinthica Fenestra vestibuli Fenestra cochleae Paries mastoidea Antrum tympanicum Paries carotica Processus lateralis Processus anterior External semicircular canal Canalis reuniens Membranous cochlea Fovea hemispherica Fovea hemi-elliptica Floor of tympanum Inner wall Fenestra ovalis Fenestra rotunda Posterior wall Mastoid antrum Anterior wall Processus brevis (of malleus) Processus gracilis MANUAL OF PRACTICAL ANATOMY. THE UPPER EXTREMITY. n^HE dissector of the upper extremity begins work on the fourth day after the subject has been placed in the dis- secting-room. He will find the body lying upon its back. The thorax is raised to a convenient height by means of blocks, and a long board is placed under the shoulders for the purpose of supporting trie arms when they are abducted from the sides. In dissecting the axilla and thorax it will be found advantageous if the dissectors of the arm and of the head and neck arrange to work at different hours. The dissector of the head and neck, at this stage, is engaged on the posterior triangle of the neck, and the dissection of the triangle cannot be well done unless the arm be placed close to the side and the shoulder depressed. For the dissection of the axilla the arm should be stretched out at right angles to the thorax. A compromise between these two posi- tions always results in discomfort to both dissectors. The upper extremity consists of the brachium or arm, the antibrachium or forearm, and the manus or hand. Connected with it are the bones of the shoulder girdle by means of which it is articulated with the skeleton of the body or trunk ; it is also connected with the body by means of a number of muscles. The angle which lies between the arm and the upper part of the trunk is the axilla or armpit. It contains a large number of important blood vessels and nerves. All the above-mentioned structures are to be examined VOL. i — i 2 THE UPPER EXTREMITY by the dissector of the upper extremity, and five days are allowed for the examination of the axilla and the muscles which pass to it from the anterior portion of the thoracic region of the body. The following table may be found useful in regulating the amount of work which should be carried out on each day : — First Day. — -(a) Surface anatomy ; (b} reflection of the skin ; (c) cutane- ous vessels and nerves of the anterior and lateral aspects of the thorax ; (d) examination of the fascia of the pectoralis major and the axillary fascia ; (e) the cleaning of the pectoralis major ; (/) the reflection of the pectoralis major. Second Day. — (a) The examination of the costo-coracoid membrane and the structures piercing it ; (b} the removal of the costo-coracoid membrane and the examination of the structures posterior to it. Third Day. — (a) The cleaning of the pectoralis minor ; (b) the cleaning of the contents of the axilla below the pectoralis minor. Fourth Day. — (a) The reflection of the pectoralis minor ; (b} the com- pletion of the cleaning of the contents of the axilla ; (c) the cleaning of the serratus anterior ; (d) the cleaning of the posterior wall of the axilla ; (e) the reflection of the subclavius ; (f) the examination of the sterno- clavicular articulation and the disarticulation of the clavicle at the sterno- clavicular joint. Fifth Day. — (a) The brachial plexus and a general review of the axilla and its contents. Surface Anatomy. — Before proceeding to the actual dis- section of any region, the student should make it an invariable practice to familiarise himself with the bony prominences within its area. It is by using these as landmarks that the surgeon is enabled to establish the positions of the component parts of the body in the living subject. At the lower part of the neck the entire length of the clavicle can be felt under the skin (Fig. i), and as the student follows its curves, with his finger, he can recognise the positions of the origins of the pectoralis major and deltoid muscles from its anterior border (Fig. 5). In a few instances these muscles may present an unbroken line of origin from the sternal to the acromial ends of the bone, but in the vast majority of cases a triangular interval is left between them. This is marked on the surface by a shallow depression, termed the delto- pectoral triangle (infraclavicular fossa), and it is rendered all the more apparent by the prominence of the shoulder on its lateral side, and the sharp backward curvature of the clavicle immediately above it. If the finger be placed in this triangle, and pressed backwards and laterally, it will rest upon the medial side of the coracoid process of the scapula. PECTORAL REGION 3 The articulations of the clavicle should also be examined. Sternal end of Acromial end of clavicl Head of humerus Nipple Lower end of body of sternun Lateral epiconclyl Medial epicondyle Ant. sup. spine of ilium f Great trochanter L Styloid process of radius IF Styloid process of ulna f~-~ Medial condyle of femur Lateral condyle of femur Patella Tibia Head of fibula Junction of manubrium with body of sternum Head of radius Symphysis " of pubis Lower end of radius Lateral malleolus J Medial malleolus Lateral malleolus FIG. i. — Surface view showing incisions and bony points. Little or no prominence is formed by the lateral extremity of the bone — its superior surface passes continuously on to the 4 THE UPPER EXTREMITY superior surface of the acromion of the scapula. By moving the limb, however, the joint can easily be detected. In strong contrast to this is the sternoclavicular joint, where the medial end of the clavicle can be felt as a marked projection, although this is masked to the eye by the sternal part of the sterno-cleido-mastoid muscle. The incisura jugularis (suprasternal notch), on the upper border of the manubrium sterni between the clavicles, should next be felt, and then the finger can be carried downwards, in the middle line, along the anterior aspect of the sternum. A prominent ridge, crossing the bone transversely at the level of the second costal cartilages, indicates the junction between the corpus sterni and the manubrium. The portion of the sternum uncovered by the two greater pectoral muscles is narrow above, but it widens out below, and suddenly, at the lower end of the corpus sterni, the finger sinks into a depression, between the cartilages of the seventh pair of ribs, and rests upon the xiphoid process. The depression is termed the in- frasternal fossa, or pit of the stomach. The costal arches below the first are easily recognised, but the first rib lies deeply under the clavicle, and can only be felt in front at its junction with the manubrium sterni. The arm should now be abducted (i.e. carried laterally from the trunk), when the hollow of the armpit will be brought into view, as well as the two rounded folds which bound it in front and behind. The anterior fold of the axilla is formed by the lower border of the pectoralis major, and to a small extent also by the lower border of the pectoralis minor. The posterior fold, which is formed by the latissimus dorsi, as it winds round the teres major muscle, is carried downwards to a lower level than the anterior fold. This, as will be seen later on, is an important point in connection with the anatomy of the axilla. If the finger be pushed upwards into the axilla the globular head of the humerus can be felt, when the arm is rotated. One other point demands the attention of the student before the dis- section is commenced, and that is, the position of the nipple. As a rule it lies superficial to the interspace between the fourth and fifth ribs, and it is situated rather more than four inches from the middle line. The student should examine these various landmarks not only upon the body but upon himself and his friends until he is perfectly familiar with them, both by touch and sight, and PECTORAL REGION 5 can at once put his finger on any given point whatever the position of the limb. Reflection of Skin. — Incisions— (i) Along the middle line of the body from the upper margin of the manubrium sterni to the tip of the xiphoid process ; (2) from the lower end of this vertical incision transversely round the lateral border of the body ; (3) from the upper extremity of the primary incision laterally along the clavicle to the extremity of the acromion process ; (4) from the lower end of the vertical and medial incision (i.e. tip of the xiphoid process) obliquely upwards and laterally, along the anterior fold of the axilla, to the point at which this joins the upper arm. Then down the arm for two and a half or three inches. Two triangular flaps of skin are marked out by these incisions, and these are now to be raised from the panniculus acliposus. But, before this is done, encircle the areola and nipple with the knife and leave the skin covering them undisturbed. Panniculus Adiposus (Superficial Fascia). — The fatty layer which is now exposed is termed the panniculus adiposus or superficial fascia. It constitutes the cushion upon which the skin rests, rounds off the angularities of the body, and varies in thickness according to the obesity of the subject. It constitutes the bed in which the cutaneous vessels and nerves ramify before they enter the skin. It is separated from the muscles by a tough, but thin, layer of fibrous tissue, devoid of fat, which forms another investment for the body ; this aponeurotic membrane receives the name of the deep fascia ; it can be readily demonstrated by making an incision in the superficial fascia, and raising a small portion of it. The superficial fascia presents here, as elsewhere, the usual characters, but, as a rule, the fat is not so plentiful. As it descends over the clavicle to the upper part of the thorax and summit of the shoulder, it has, in most cases, a faintly ruddy striated appearance. Should this not at first be apparent, the removal of some of the superficial fat will render it visible. This appearance is .due to the presence of a number of sparse scattered muscular fasciculi which stream down over the clavicle, to obtain attachment in the panniculus adiposus over the pectoralis major and deltoid muscles. In the neck they form a thin, cutaneous, fleshy stratum, called the platysma myoides. The superficial fascia in this region is also specialised by the development of the mamma in its substance. It should now be dissected, with the view of exposing the mamma as well as the cutaneous vessels and nerves which make it their bed before entering the skin. i— la 6 THE UPPER EXTREMITY Dissection. — In searching for a cutaneous nerve, cut boldly down through the superficial fascia in the direction in which the nerve runs until the plane at which the superficial and deep fascia blend is reached. It is here that the main trunks are to be found ; and in a well-injected subject the cutaneous arteries furnish the best guides. Nervi Cutanei, Arteriae Cutaneae (Cutaneous Nerves and Arteries). — There are three distinct groups of cutaneous nerves for the supply of the skin on the anterior and lateral parts of the thorax. They are : — 1. The supraclavicular nerves — from the cervical plexus. 2. The anterior cutaneous, \from the anterior rami (intercostal) 3. The lateral cutaneous, J of the thoracic nerves. The supraclavicular nerves arise in the neck from the third and fourth cervical nerves, and, spreading out as they descend, they cross the clavicle under cover of the platysma. They are classified, according to their positions, into the anterior, the medial, and the posterior branches. The anterior are the smallest of the series ; they cross the medial part of the clavicle to end in the skin immediately below. The medial branches pass over the middle of the clavicle and extend downwards, in the superficial fascia over the pectoralis major, as far as the third rib. The posterior cross the lateral third of the clavicle, and will be afterwards followed to the skin of the shoulder. These nerves can readily be found by cutting down upon the clavicle through the platysma, and in the direction of its fibres. The anterior cutaneous nerves are the minute terminal twigs of the anterior branches of the thoracic nerves. They become superficial by piercing the pectoralis major muscle and deep fascia close to the margin of the sternum. One will be found in each intercostal interval, and they are accompanied by the cutaneous perforating branches of the internal mammary artery, which (when injected) serve as the best guides to the nerves. They give slender twigs to the skin over the sternum, and larger branches which are directed laterally, and may be traced as far as the anterior fold of the axilla. The lateral cutaneous nerves^ much larger than the pre- ceding, arise from the anterior rami of the thoracic nerves, and appear on the side of the thorax, along a line situated a little behind the anterior fold of the axilla. They pierce the wall of the thorax in the interspaces between the ribs, and divide into anterior and posterior branches under PECTORAL REGION 7 cover of the serratus anterior muscle. At a later stage these branches will be found appearing between the digita- tions of the serratus anterior. The anterior branches come out, as a rule, about an inch in front of the corresponding posterior branches, and then proceed forwards over the lower border of the pectoralis major muscle, where they should be sought for at once. From the lower members of this series some minute twigs are given off, which enter the superficial M. teres major M. latissimus dorsi M. pectoralis major Lobules of the gland Ampullae of ducts I M. serratus ant Fibrous trabeculae of the gland "" FIG. 2. — Dissection of the Mamma. surface of the digitations of the external oblique muscle of the abdomen. The posterior branches run backwards, to the dorsal aspect of the trunk, over the anterior border of the latissimus dorsi muscle. It is advisable not to attempt to secure the two highest lateral cutaneous nerves (i.e. those issuing from the second and third intercostal spaces) in the meantime. They are best dissected along with the other contents of the axilla. Dissection. — If the subject be a female the dissector should endeavour to make out the connections, and also something of the structure, of the mamma. The small area of skin which has been left over the areola should be raised towards the summit of the nipple, and bristles may be introduced through the orifices of the ducts which may be seen on the 1—16 8 THE UPPER EXTREMITY extremity of the nipple. Further, by removing the fat which surrounds the organ the true glandular tissue will be rendered more apparent. It is only in favourable circumstances that the milk-ducts in the nipple and their ampullae in the region of the areola can be isolated and rendered apparent. The Mamma (Mammary Gland or Breast). — In the female the mamma forms a rounded prominence on the front and Processes radiating out from the corpus mammae Ampulla Ductus lactiferi Pectoralis major Fat lobule FIG. 3. — Section through a Mammary Gland prepared by method recommended by Mr. Harold Stiles. also, to some extent, on the lateral aspect, of the thorax. It lies in the superficial fascia, and its smooth contour is largely due to the invasion of its substance by the fatty tissue of this layer. A little below its mid-point, and at a level which usually corresponds to the fourth intercostal space, the mamma is surmounted by a conical elevation termed the papilla mammce. or nipple. This stands in the middle of a circular PECTORAL REGION 9 patch of .coloured integument which is called the areola mamma. Within the nipple, and also subjacent to the areola, there is no fat. A curious change of colour occurs in this region during the second month of pregnancy. At that time the delicate pink colour of the skin of the nipple and areola of the virgin becomes converted to brown, by the deposition of pigment, and it never again resumes its original appearance. The mamma extends, in a horizontal direction, from the side of the sternum to very nearly the mid-axillary line on the side of the thorax, and, in a vertical direction, from the second costal arch above to the sixth costal cartilage below. About two-thirds of the gland are placed upon the pectoralis major muscle, whilst the remaining part, which corresponds to its inferior and lateral third, extends beyond the anterior fold of the axilla, and lies upon the serratus anterior muscle. From the part which lies in relation to the lower border of the pectoralis major a prolongation extends upwards into the axilla, and reaches as high as the third rib. The mamma is not isolated by a capsule from the surrounding fatty tissue of the superficial fascia. Pervading it, and supporting the true glandular substance, there are strands or trabeculae of connective tissue which constitute its stroma or framework, and these are directly continuous with the fibrous tissue which supports the fat of the superficial fascia. The stroma and gland-substance together constitute a conical mass termed the corpus mamma. Processes pro- ject out from both the surface and margins of the corpus mammae, and in the hollows between these projections is deposited the fat which gives the smooth contour to the organ. Many of the processes which extend from the super- ficial surface are attached to the deep surface of the skin. They form the so-called ligaments of Cooper. The gland substance is arranged in lobes and lobules, and the ducts issuing from these converge towards the areola. Some fifteen or more lactiferous ducts pass towards the base of the nipple. Subjacent to the areola the ducts expand into fusiform dilatations termed the sinus lactiferi, and then, contracting, they traverse the substance of the nipple, upon the summit of which they open. In a well - injected subject twigs from the intercostal arteries, and also from the perforating branches of the io THE UPPER EXTREMITY internal mammary artery, may be traced into the mamma; and other vessels, called the external mammary branches of the lateral thoracic artery, may be seen winding round the edge of the pectoralis major, or piercing its lower fibres, to reach the gland. By means of lymphatic vessels the mamma is brought into connection with the sternal lymph glands, and also, more directly, with the axillary lymph glands. The latter con- nection is one of much importance to the surgeon in cases where it is necessary to remove the organ for malignant disease. In the male the mamma (mamma virilis) is extremely rudimentary. The nipple is small and pointed, and the areola is surrounded by sparse hairs. Deep Fascia. — The deep fascia of the pectoral region is a thin membrane which closely invests the pectoralis major. It is attached above to the clavicle, and medially to the front of the sternum. Below, it is continuous with the deep fascia covering the abdominal muscles, and, at the lower border of the pectoralis major muscle, it is continuous with the axillary fascia. At the deltopectoral triangle a process from its deep surface dips in between the deltoid and pectoralis major muscles to join the costo-coracoid membrane, whilst, further laterally, the aponeurosis becomes continuous with the fascia covering the deltoid muscle. The costo- coracoid membrane will be described later on. Fascia Axillaris (Axillary Fascia). — The axillary fascia is a dense felted membrane which extends across the base of the axilla. It is continuous anteriorly with the deep fascia over the pectoralis major, posteriorly with the fascial sheaths of the latissimus dorsi and the teres major muscle, medially with the deep fascia on the surface of the serratus anterior, whilst laterally it is continuous with the deep fascia on the medial surface of the upper part of the arm. It is drawn up towards the hollow of the axilla, and the elevation is due chiefly to the connection of its deep surface with the fascial sheath of the pectoralis minor, and partly to its attachment to the areolar tissue which fills the axillary space. In a well- injected subject a small artery, from the lower part of the axillary trunk, may be seen ramifying on the surface of the fascia. Dissection. — The pectoralis major muscle must now be cleaned, and its PECTORAL REGION n division into sternal and clavicular parts clearly made out. The muscular fibres are rendered tense by abducting the arm from the side. On the right side the dissector begins at the inferior border of the muscle, whilst on the left side he commences at the superior border. He must also clean the anterior margin of the deltoid. In the interval between the deltoid and the clavicular portion of the pectoralis major the cephalic vein and, subjacent to it, the deltoid branches of the thoraco-acromial artery, and the infraclavicular lymph glands will be found. .The "cleaning" of a muscle means the removal of the whole of the deep fascia from its surface. To do this successfully the dissector must Chain of glands related to the axillary vessels Cephalic vein [. pectoralis major \ M. serratus anterior M. pectoralis minor Pectoral glands M. latissimus dorsi M. pectoralis major Lymphatic vessels to sternal glands FIG. 4. — The Lymph Glands and Vessels of the Axilla and Mamma. (From Poirier and Cuneo — modified.) follow three rules, (i) He must cut boldly down through the deep fascia till he exposes the red fibres of the muscle. (2) As he removes the fascia he must keep the knife edge playing against the fibres of the muscle. (•3) As he makes his cuts he must carry the knife blade in the direction of the fibres of the muscle. If he follows rules I and 2 he will not leave a thin film of fascia on the muscle, and as he follows rule 3 he will find that the direction of his incisions change as the course of the fibres of the muscle changes. If the work is well done the deep fascia should be removed from the muscle as a continuous unperforated layer of fibrous tissue, and the surface of the muscle will be clean. Lymphoglandulse Infraclaviculares (Infraclavicular Lymph Glands). — In the interval between the adjacent margins of 12 THE UPPER EXTREMITY the pectoralis major and deltoid muscles, immediately below the clavicle, are placed one, or it may be two, lymph glands which receive the lymphatic vessels which accompany the cephalic vein. These vessels convey the lymph from the lateral side of the arm and the shoulder. M. Pectoralis Major. — This powerful muscle extends from the anterior aspect of the thorax to the humerus. „ It .is divided by a deep fissure into a clavicular and a sternocostal portion. The fissure" penetrates through the entire thickness of the muscle, the clavicular and sternocostal portions being thus distinct, except close to their insertion. The clavicular portion arises by short tendinous and muscular fibres from an impression on the medial half of the anterior surface of the Trapezoid ligament Costo-clavicular ligament Conoid ligament FIG. 5. — Under Surface- of the Clavicle with the Attachments of the Muscles mapped out. clavicle. The superficial part of the sternocostal portion takes origin by fleshy fibres from the anterior surface of the sternum, from the aponeurosis of the external oblique muscle, and, occasionally, from the sixth rib near its cartilage. The deeper part rises by a variable number of muscular slips from the cartilages of the upper six ribs. The pectoralis major is inserted, by a flattened bilaminar tendon, into the lateral lip of the sulcus intertubercularis of the humerus, and the fibres of the muscle undergo a re- arrangement as they converge upon this tendon. The greater part of the clavicular portion joins the anterior lamina of the common tendon ; some of the most medial clavicular fibres, however, are inserted directly into the humerus below the tendon, whilst a few gain attachment to the deep fascia of the arm, and others become adherent to the adjacent part of the deltoid. The fibres of the sternocostal portion of the muscle take AXILLARY SPACE 13 different directions as they proceed to join both laminae of the tendon of insertion ; thus the superior fibres descend slightly, the intermediate fibres pass horizontally, whilst the inferior fibres ascend, and, at the same time, gain the deep surface of the rest of the muscle. A smooth, full, and rounded lower border is in this way formed which constitutes the anterior fold of the axilla. The precise manner in which the muscle is attached to the humerus will be more fully studied at a later stage of the dissection (p. 56). The pectoralis major is supplied by the medial and lateral anterior thoracic nerves. Axilla. — The axilla may be defined as being the hollow or recess between the upper part of the side of the thorax and the upper part of the arm. When the limb is abducted from the trunk, and the areolo-fatty tissue which occupies the axilia is removed, the 'space presents a pyramidal form. The apex, or narrow part of the space, placed immediately to the medial side of the coracoid process, is directed upwards towards the root of the neck, whilst the wider part or base looks downwards. The medial wall formed by the thorax is of greater extent than the lateral wall formed by the arm. It follows from this, therefore, that the anterior and posterior walls converge as they proceed laterally, and because the posterior wall is longer than the anterior, the posterior border of the base is lower than the anterior. Before engaging in the dissection of the space, it is necessary that the student should have some knowledge of its boundaries, and the manner in which its contents are disposed in relation to these. Boundaries of the Axilla. — The anterior wall is formed by the two pectoral muscles and the costo-coracoid membrane. The pectoralis major constitutes the superficial stratum, and is spread out over the entire extent of the anterior wall. The pectoralis minor, which lies subjacent to the pectoralis major, is only in relation to about one-third of the anterior boundary, whilst the interval or gap between this muscle and the clavicle is filled up by the costo-coracoid membrane. The lower border of this wall of the axilla is the anterior fold of the axilla. It is formed by the lower margin of the pectoralis major, strengthened, medially, by a small part of the lower border of the pectoralis minor, which comes into view near the side of the thorax. The posterior wall of the axilla is somewhat longer than 14 THE UPPER EXTREMITY the anterior wall. It is formed, from above downwards, by the subscapularis muscle, the tendon of the latissimus dorsi, and the teres major muscle. The subscapularis, covering the costal surface of the scapula, takes by far the largest share in the formation of this wall. The narrow tendon of the latissimus dorsi conceals the front of the teres major and only the lower border of the latter muscle is seen below it. The posterior fold of the axilla is formed by the lower border of this wall. The medial wall is constituted by the upper four or five ribs with the intervening intercostal muscles ; it is clothed by the corresponding digitations of the serratus anterior muscle. The lateral wall is formed by the humerus and the conjoined 9 10 J38 4 1. Upper end of humerus. 2. Scapula. 3- Rib. 4. Pectoralis major. 5. Serratus anterior. 6. Subscapularis. 7. Axillary vein. 8. Axillary artery. 9. Long head of biceps. 10. Conjoined origin of short head of biceps and coraco-brachi- alis. 11, 12, 13. Brachial nerves. FIG. 6. — Diagram of section through the Axilla of the Left Side. proximal parts of the coraco-brachialis and short head of the biceps brachii. The apex of the space corresponds with the narrow com- munication between the axilla and the root of the neck. It is a triangular interval (which can readily be investigated by the finger when the space is dissected) bounded by the clavicle, first rib, and upper margin of the scapula, and through it pass the great axillary vessels and brachial nerves on their way from the neck to the arm. The wide base of the axilla is closed by the vaulted axillary fascia. Contents of the Axilla. — The axillary artery and vein, with the great brachial nerves and the axillary lymph vessels and lymph glands, constitute the most important contents of the axilla. Except at the summit of the space, they lie close to the lateral wall, and follow it in all the movements of the arm. Dissection. — Cut through the clavicular fibres of the pectoralis major, AXILLARY SPACE 15 immediately below their attachment to the clavicle, and turn them distally towards their insertion. Whilst doing this secure the branches of the lateral anterior thoracic nerve as they pass into the muscle. Under cover of the clavicular part of the pectoralis major follow the cephalic vein and the deltoid branch of the thoraco-acromial artery medially and secure the acromial and pectoral branches of the latter artery. Clean these vessels, and directly below the clavicle display the costo-coracoid membrane, and, more inferiorly and laterally, the fascia on the proximal and lateral part of the pectoralis minor. Cut through the sternocostal part of the pectoralis major about two inches from the lateral border of the sternum. Turn the medial part towards the medial plane, verifying its attachment to the costal cartilages and to the sternum and to the aponeurosis of the external oblique muscle of the abdomen. Turn the lateral part of the muscle towards the arm ; whilst doing this secure the medial anterior thoracic nerve which perforates the pectoralis minor and ends in the pectoralis major. Examine the insertion of the pectoralis major. Note that the tendon of insertion consists of two laminae which are united together below ; in other words, the tendon is folded on itself and between the two laminae a tmicous bursa is frequently interposed. The clavicular fibres and the upper sternocostal fibres are attached to the anterior lamina ; the lower sternocostal fibres to the posterior lamina. Both lamina: are attached to the lateral lip of the intertubercular sulcus of the humerus, but the deep lamina ascends to a higher level, and it becomes continuous above with a layer of fascia which is attached to the small tubercle of the humerus. The inferior border of the tendon of insertion is continuous with the deep fascia of the arm. When the pectoralis major is completely reflected a continuous sheet ot fascia is exposed, which extends from the clavicle superiorly to the axillary fascia inferiorly and from the wall of the thorax medially to the arm laterally ; this is the so-called davipectoral fascia or suspensory ligament of the axilla. It is because of the attachment of this fascial sheet to the clavicle superiorly and to the axillary fascia inferiorly that the floor of the axilla is raised when the clavicle is elevated as the arm is abducted from the side. The pectoralis minor muscle, passing obliquely from its origin on the thoracic wall to its insertion into the coracoid process of the scapula, runs through the substance of the clavipectoral fascia and divides it into three parts : (i) the part above the muscle, (2) the part which encloses the muscle, and (3) the part below the muscle. The uppermost part is the costocoracoid membrane, the intermediate part is the sheath of the pectoralis minor. No special term is applied to the lowest part, but it should be noted that it lies posterior to the lower part of the pectoralis major, and that it covers the lower portions of the axillary vessels and nerves. Membrana Costocoracoidea (Costo-coracoid Membrane).— The costo-coracoid membrane occupies the gap between the clavicle above and the pectoralis minor below. It extends from the first rib medially to the coracoid process laterally, and from the clavicle above to the pectoralis minor below. Its upper part is split into two layers, an anterior and a posterior, which are attached to the corresponding borders of the clavicle. Enclosed between them is the subclavius muscle. The strongest part of the membrane is that which extends along the lower border of the subclavius, from the first rib to 1 6 THE UPPER EXTREMITY the coracoid process ; this portion is frequently called the costo-coracoid ligament. The membrane is continuous below with the fascial sheath of the pectoralis minor and posteriorly with the fascial sheath of the axillary vessels. It is perforated, above the upper border of the pectoralis minor, by the cephalic vein, the thoraco-acromial artery, and the lateral anterior thoracic nerve. Note that the fibres of the membrane run medio-laterally, that they are put on the stretch when the arm is abducted, and that they are relaxed when the arm is by the side. The surgeon takes advantage of these facts when he is ligaturing the first part of the axillary artery. Clavicle — ,/— Subclavius Thoraco-acromial artery "Y. First rib Costo-coracoid membrane Axillary artery Axillary sheath -Axillary fascia FIG. 7. — Diagram of the Costo-coracoid Membrane. Dissection.— Cut through the anterior layer of the upper part of the costo-coracoid membrane and expose the subclavius muscle. Pass the handle of a knife below the lower border of the subclavius and upwards behind the muscle and demonstrate the posterior layer of the upper part of the membrane. Clear away the remains of the membrane and follow the cephalic vein to its junction with the axillary vein, the thoraco-acromial artery to the axillary trunk, and the lateral anterior thoracic nerve to the lateral cord of the brachial plexus. Clean the upper parts of the axillary artery and vein and the lateral cord of the brachial plexus. Note that the axillary vein lies to the medial side of the artery on a somewhat anterior plane, and that as the arm is abducted from the side the vein passes more and more in front of the artery. The lateral cord of the plexus lies to the lateral side of the artery and on a posterior plane. Behind the upper border of the pectoralis minor find the medial anterior thoracic nerve, and note that an anastomosis is formed between the medial and lateral anterior thoracic nerve across the front of the artery and behind the costo-coracoid membrane. AXILLARY SPACE 17 Clean the pectoralis minor muscle without injuring the medial anterior thoracic nerve which pierces it. M. Pectoralis Minor. — The pectoralis minor is a triangular muscle which rises from the anterior ends of the third, fourth, and fifth ribs close to their junctions with their cartilages and from the fascia covering the intercostal muscles in the intervening spaces. Its fibres pass upwards and laterally, and its tendon of insertion is attached to the upper surface and the anterior border of the coracoid process near its lateral extremity. When the muscle is in action it draws the scapula downwards and forwards and depresses the shoulder. It is supplied by the medial anterior thoracic nerve. The greater portion of the pectoralis minor is concealed by the pectoralis major, but the medial part of its inferior border appears on the lateral wall of the thorax below the pectoralis major ; its insertion is concealed by the anterior fibres of the deltoid. Dissection. — Clear away the clavipectoral fascia below the level of the pectoralis minor and open up the lower part of the axilla, remove also the deep fascia of the arm in the region of the lateral boundary of the axilla. Commence at the lateral part of the area below the pectoralis minor and clean the coraco-brachialis and the short head of the biceps as they descend into the arm from the tip of the coracoid process. Find the lower part of the axillary artery at the medial border of the coraco-brachialis. The trunk of the median nerve lies between the artery and the muscle, and at the lower border of the pectoralis minor the medial head of the nerve crosses the front of the artery. Pull the coraco-brachialis laterally and find the musculo-cutaneous nerve entering its deep surface, just below the pectoralis minor. Above and to the lateral side of the trunk of the musculo- cutaneous nerve find the branch from it which supplies the coraco-brachialis. The axillary vein lies along the medial side of the artery, and in the angle between the artery and vein, anteriorly, is the medial cutaneous nerve of the forearm (internal cutaneous). Running along the medial side of the vein is the medial cutaneous nerve of the arm (lesser internal cutaneous nerve) ; secure this and follow it upwards to the communication which it receives from the intercosto-brachial nerve. At the same time identify and preserve the lateral group of axillary lymph glands which lie along the medial side of the axillary vein. Secure the intercosto-brachial nerve and follow it medially, to the point where it emerges from the second intercostal space, and laterally to the medial and posterior aspect of the arm where it is distributed. In order to display the distribution of the intercosto-brachial nerve, and to give better access to the medial and posterior walls of the axilla, the axillary fascia must be separated from the fascia of the arm. When this has been done the dissector should turn to the medial wall of the axilla and find the anterior and posterior divisions of the lateral branches of the intercostal nerves, as they emerge between the digitations of the serratus anterior behind the inferior border of the pectoralis minor. These he must trace forwards and backwards respectively, and he may expect to find VOL. I — 2 i8 THE UPPER EXTREMITY an anastomosis between the posterior division of the third lateral branch and the intercostobrachial nerve. At the junction of the anterior and medial walls of the axilla and at the lower border of the pectoralis minor Posterior circumflex artery Subscapular artery < Musculo-cutaneous nerve ! Axillary nerve (O.T. circumflex) Cephalic vein Acrpmial artery Lateral anterior thoracic nerve Lateral cord of brachial plexus Thoraco-acromial artery Axillary artery, ist pait Axillary vein Subclavius muscle edial anterio horacic nerv Anterior circumflex artery Pectoralis major Coraco-brachialis Biceps brachii (short head) liasilic vein Brachial artery Median nerve Fascial band connecting dorsi with long head of t Medial anti-brachial cutan nerve Ulnar nerve ! Medial brachial cutaneous nerv \ Teres major Radial nerve (O.T. musculo- spiral Circumflex artery of scapula (O.T. 1 dorsalis scapulae) Lower subscapular nerve Subscapularis muscle I Posterior division of lateral cuUneous nerve ! Latissimus dcrsi Thoraco-dorsal nerve (O.T. middle subscapular) interior branch of a ral cutaneous nerve Lateral thoracic artery (O.T. long thoracic) Long thoracic nerve Intercosto-brachial nerve FIG. 8. — The contents ot the Axillary Space exposed by the reflection of the Pectoralis Major and the subjacent fascia on the removal of the fat and glands. find the lateral thoracic artery ; clean the artery and the medial group of axillary lymph glands which lie along its course. At the junction of the posterior and anterior two-thirds of the medial wall of the axilla find the long thoracic nerve, which supplies the serratus anterior and descends along its lateral surface from the apex to the base of AXILLARY SPACE 19 the axilla. After the nerve has been secured the serratus anterior must be cleaned. When this has been done the dissector should clean the lower parts of the axillary vessels and nerves and their branches and tributaries. Commence at the lower border of the pectoralis minor and find the subscapular artery. It springs from the medial and posterior part of the axillary trunk and runs distally and medially along the lower border of the subscapularis muscle. Follow the artery and, whilst doing so, clean the posterior group of the axillary lymph glands which lie along its course and secure the thoracodorsal nerve (long subscapular), which joins the artery near the junction of the lateral and posterior walls of the axilla and ter- minates in the latissimus dorsi, which it supplies. Rising from the upper part of the subscapular artery is its large circumflex scapular branch which passes backwards through the posterior wall of the axilla. In the angle be- tween this branch and the main trunk will be found the lower subscapular nerve which supplies the teres major and the lower fibres of the subscapularis. The dissector should now thoroughly clean the lower part of the axillary artery and vein, the medial cutaneous nerve of the forearm which lies in the angle between them anteriorly, and the median cutaneous nerve of the arm which lies along the medial side of the vein ; then he should pull the vein forwards and laterally, and in the angle between it and the artery, posteriorly, he will find the ulnar nerve ; this also should be pulled forwards and laterally to display the axillary (circumflex) nerve, which turns back- wards at the lower border of the subscapularis above the level of the circumflex scapular artery, and the radial (musculo-spiral) nerve, which descends behind the axillary artery to the lower border of the axilla. Spring- ing from the upper part of the radial (musculo-spiral) nerve are '^posterior brachial cntaneotts branch and muscular branches to the long and medial heads of the triceps muscle ; these branches may rise separately from the radial nerve or they spring from it by a common trunk which afterwards divides into the individual branches. Trace 'the posterior brachial cutaneous nerve to the back of the arm behind the intercosto-brachial nerve ; follow the nerve to the long head of the triceps till it enters the muscle. The nerve to the medial head of the triceps is usually a long slender branch which is known as the ulnar collateral nerve because it accompanies the ulnar nerve to the lower part of the arm. It will be traced to its termination at a later period. The anterior and posterior humeral circumflex branches of the axillary artery .will be found springing from the artery a short distance below the subscapular branch, the former rising from the anterior and the latter from the posterior aspect of the axillary trunk. When the lower part of the axilla has been thoroughly cleaned, the pectoralis minor must be divided, about midway between its origin and insertion, and the two parts must be turned aside. When this has been done the upper subscapular nerve must be found entering the upper part of the subscapularis, and then the remaining areolar tissue must be removed from the axillary space, the trunks and branches of the axillary vessels and nerves must be thoroughly cleaned, and the contents of the space must be studied in detail. Lymphoglandulse Axillares (Axillary Lymph Glands).— The lymph glands in the axillary region are spoken of, collectively, as the axillary glands, but for convenience of description, and to facilitate a more precise knowledge of their connections and associations, they are subdivided into 20 THE UPPER EXTREMITY several subordinate groups. Some of the glands have been removed as the dissection proceeded, and others are so small that they may have escaped the attention of the dissector, but if he has followed the directions given above he will have noted at least four groups of glands, (i) A lateral or brachial group consisting of six or more glands, which extend along the axillary vessels. They receive the lymphatics from Cephalic vein M. pectoralis major \ M. deltoideus Chain of glands related to the axillary vessels M. serrntus anterior M. pectoralis minor Pectoral glands M. latissimus dorsi M. pectoralis major Lymphatic vessels to sternal glands FIG. 9. — The Lymph Glands and Vessels of the Axilla and Mamma. (From Poirier and Cuneo — modified. ) the greater part of the upper extremity, and those at the upper part of the chain also receive lymph from the deep part of the mamma. (2) A pectoral group, or medial group, which lies in the angle between the anterior and medial walls of the axilla. This is subdivisible into two parts : (a) an upper group of two or three small glands which lie beneath the pectoralis major in the region of the second and third intercostal spaces — these receive lymph from. the anterior wall of the thorax and from the lateral two-thirds of the mamma ; (b} an inferior group which lies along the posterior border of AXILLARY SPACE 21 the lateral thoracic artery, and receives lymph from the lateral wall of the thorax. (3) A posterior or subscapular group which lie along the subscapular artery on the posterior wall of the axilla, and receive lymphatics from the back. (4) The infraclavicular glands, a group of two or three small glands which lie in the deltopectoral triangle and receive lymph from the upper and lateral parts of the arm. In addition a centra] or intermediate and a subclavicular group of glands are described. The central group lies either on the super- ficial aspect of the axillary fascia, in a pocket of its sub- stance, or deep to the axillary fascia embedded in the adipose tissue of the axilla. The subclavicular glands, from six to twelve in number, lie in the apex of the axilla, they receive afferent vessels from all the lower groups, and their efferents unite together to form the subdavian lymphatic trunk. The student should note that although the various subgroups are more or less separate, and are particularly associated with definite regions from which they receive lymph, nevertheless they are linked together by lymphatic vessels ; therefore micro-organisms which have gained entry into the lymph stream and lymph-borne cancer cells can readily pass from one subgroup to another. Kami Laterales (O.T. Lateral Cutaneous Branches) of the Anterior Divisions of the Second and Third Thoracic Nerves. — As a rule, the first thoracic nerve does not give off a lateral branch. That which springs from the second thoracic nerve is the largest of the series, and differs from the others in not dividing into an anterior and posterior branch. It is termed the intercosto-brachial nerve, on account of its being distributed to the skin on the medial and dorsal aspects of the upper part of the arm. To reach this destination it crosses the axilla and pierces the deep fascia. But before doing so it establishes communications and forms a plexiform arrange- ment in the axilla with the medial brachial cutaneous nerve, and the lateral cutaneous branch of the third thoracic nerve. This plexus may be joined by another twig, which is occa- sionally present, viz. the minute lateral cutaneous branch of the first thoracic nerve. The lateral cutaneous branch of the third thoracic nerve divides into an anterior and posterior part, which are dis- tributed in the ordinary way. From the posterior branch twigs are given to the skin of the axilla, and the terminal 22 THE UPPER EXTREMITY twigs are distributed to the integument on the upper part of the medial aspect of the arm. Posterior circumflex artery Anterior circumflex artery Subscapular artery Musculo-cutaneous nerve Axillary nerve (O.T. circumflex) ; Cephalic vein Acrpmial artery Lateral anterior thoracic nerve Lateral cord of brachial plexus Thoraco-acromial artery ••, Axillary artery, ist pait •, ,\ Axillary vein Pectoralis major f Coraco-brachialis '' f Biceps brachii (short head) y o ; Basilic vein y\ *. Brachial artery \ Median nerve toral branch of thoraco- omial artery, Ulterior branch of a •al cutaneous nerve I Fascial band connecting 1 I dorsi with long head of tri Medial anti-brachial cutane< Medial brachial cutaneous nerve \ Tcres major Radial nerve (O.T. musculo-spiral) Circumflex'artery of scapula (O.T. dorsalis scapulae) Lower subscapular nerve Subscapularis muscle Posterior division of lateral cutaneous nerve Latissimus dorsi ! Thoraco-dorsal nerve (O. T. middle subscapular) im-mm ( Long thoracic nerve Intercosto-brachial nerve Lateral thoracic artery (O.T. long thoracic) FIG. 10. — The contents of the Axillary Space exposed by the reflection of the Pectoralis Major and the subjacent fascia and the removal of the fat and the lymph glands. Arteria Axillaris (The Axillary Artery) is the chief artery of the upper limb. It commences as the continuation of the subclavian artery, and enters the axilla at its apex, at the lateral border of the first rib. It lies, for a short distance, AXILLARY SPACE 23 on the medial wall of the axilla, crosses the interval between the medial and posterior walls, and then runs along the lateral wall to the lower border of the teres major, where it leaves the axilla, and, passing into the arm, becomes the brachial artery. For convenience of description it is usually divided into three parts, the part above, the part behind, and the part below the pectoralis minor, which are known respectively as the first, second, and third parts. The direction of the course of the artery varies with the position of the limb. When the arm is at a right angle with the body, the direction is that of a straight line from the centre of the clavicle to the middle of the bend of the elbow. When the arm is by the side, the artery describes a curve with the convexity directed laterally ; and if the arm is raised above the head the curve formed by the artery is convex in the reverse direction. The first part of the axillary artery lies very deeply. It is covered by the skin, superficial fascia, deep fascia, clavicular part of the pectoralis major, the costo-coracoid membrane, and the vessels and nerves superficial to it. But, even when these are removed, the vessel is not completely exposed, because it is enveloped, along with the axillary vein and great nerves, by a funnel-shaped sheath, which is prolonged upon them from the deep cervical fascia, and by the loop of communication between the two anterior thoracic nerves which lies in front of the sheath. Posteriorly, this part of the vessel is supported by the first intercostal space and the first digitation of the serratus anterior muscle, and the long thoracic nerve and the medial cord of the brachial plexus cross behind it. To its medial side, and somewhat overlapping it, is the axillary vein, whilst above and to its lateral side are the lateral and posterior brachial nerve-trunks. The second part of the axillary artery is placed behind the two pectoral muscles, and has the three cords of the brachial plexus disposed around it. Thus the medial cord lies upon its medial side, the lateral cord upon its lateral side, and the posterior cord behind it. The axillary vein is still upon its medial side, but is separated from the artery by the medial nerve-cord. Strictly speaking, it is not in apposition with any muscle posteriorly, being separated from the sub- scapularis muscle by areolo-fatty tissue. The third and longest part of the axillary artery is superficial 24 THE UPPER EXTREMITY in its distal half. This is due to the fact that the posterior wall of the axilla extends more distally than the anterior wall. Whilst, therefore, it is covered in its proximal half by the pectoralis major, below this it is only covered by the skin and fascia. Behind it proximo-distally are the subscapularis, the tendon of the latissimus dorsi, and the teres major, but it is separated from the subscapularis muscle by the axillary (circumflex) and radial (musculo- spiral) nerves, and from the latissimus dorsi and the teres Lateral cord Posterior cord Medial cord Musculo-cutaneous nerve Median nerve (lateral head) Median nerve (medial head) Medial antibrachial cutaneous nerve Medial brachial cutaneous nerve Median nerve Radial nerve (musculo-spiral) Ulnar nerve FIG. ii. — Diagram to show relation of Axillary Vessels and Nerves. major by the radial nerve. To its lateral side is the coraco- brachialis muscle, but between the muscle and the artery are the musculo-cutaneous and the median nerves. To the medial side of the artery is the vein with the medial cutaneous nerve of the forearm in the angle between the artery and vein anteriorly, and the ulnar nerve in the angle between the artery and vein posteriorly. The medial cutaneous nerve of the arm lies along the medial side of the vein. The branches of the axillary artery have been seen at different stages of the dissection. They may now be more fully examined. They are :— AXILLARY SPACE A. thoracalis suprema \from the first / part. . If—second A. thoracalis lateralisl Partl A. subscapularis . A. circumflexa humeri anterior A. circumflexa humeri posterior ^ from the third part. A. Thoracalis Suprema (O.T. Superior Thoracic). — This is a small branch which springs from the axillary at the lower border of the subclavius. It ramifies upon the upper part of the medial wall of the axilla and supplies twigs to adjacent structures. A. Thoracoacromialis (O.T. Acromio-thoracic or Thoracic Axis). — The thoraco-acromial artery is a short, wide trunk, which takes origin under cover of the pectoralis minor. It winds round the upper border of that muscle, pierces the costo- coracoid membrane, and immediately divides into numerous branches, which diverge widely from each other. These re- ceive different names, and are arranged as follows : — (a) The ramus clavicularis, a small twig, which runs up wards to the clavicle and then turns medially along that bone between the clavicular part of the pectoralis major and the costocoracoid membrane. (ft) The rami perforates, of larger size, proceed downwards be- tween the two pectoral muscles, give branches to both, and they anastomose with the lateral thoracic and the lateral branches of the intercostal arteries, (c] The ramus acromialis runs laterally upon the tendon of the pectoralis minor and the coracoid process. Some of its twigs supply the deltoid, whilst others pierce it to reach the superior surface of the acromion. It anastomoses with the transverse scapular (suprascapular) and posterior circumflex humeral arteries. (d) The ramus deltoideus, as a rule, takes origin from a trunk common to it and the preceding artery. It runs distally in the intermuscular interval between the pectoralis major and the deltoid and supplies both muscles. A. Thoracalis lateralis (O.T. Long Thoracic). — This vessel takes the lower border of the pectoralis rm'nor as its guide, and proceeds distally and medially to the side of the thorax. It gives branches to the neighbouring muscles, and it anastomoses with twigs from the intercostal arteries. It also supplies the mamma, giving off, as a rule, an external mammary branch, which winds round or pierces the lower border of the pectoralis major on its way to the gland. Alar Thoracic. — This small artery supplies the fat and lymph glands 26 THE UPPER EXTREMITY in the axilla, but it is rarely present as a separate branch, and its place is usually taken by twigs from the subscapular and lateral thoracic arteries. A. Subscapularis. — The subscapular artery is the largest branch of the axillary artery. It arises opposite the inferior border of the subscapularis muscle and, following this, it runs downwards and backwards, to the inferior angle of the scapula, where its terminal twigs anastomose with the descending branch of the transverse cervical artery. In the lower part of its course it is accompanied by the thoracodorsal nerve. Not far from its origin the subscapular artery gives off a large branch, the A. rircumflexa scapula, which winds round the axillary border of the scapula, in close contact with the bone, to reach its dorsal aspect. Numerous smaller twigs are given to the neighbouring muscles. Aa. Circumflexse Humeri (O.T. Anterior and Posterior Circumflex Arteries). — These are two in number, and as a rule they both arise from the axillary at the same level, a short distance distal to the origin of the subscapular artery. The arteria circumflexa humeri posterior is much the larger of the two. Only a small portion of it can be seen at the present stage. It springs from the posterior aspect of the axillary, and at once proceeds backwards, with the axillary nerve, close to the medial and dorsal aspect of the head of the humerus, and in the interval between the subscapularis and teres major muscles. The small arteria circumflexa humeri anterior takes origin from the lateral aspect of the axillary, and runs laterally, in front of the surgical neck of the humerus, under cover of the coraco-brachialis and short head of the biceps brachii. Reaching the sulcus intertubercularis, it divides into two branches. Of these one is directed proximally, along the long head of the biceps brachii, to the shoulder-joint ; the other passes laterally, to the under surface of the deltoid, and finally anastomoses with some of the terminal twigs of the posterior circumflex artery of the humerus. Vena Axillaris (The Axillary Vein). — This vein has the same extent as the artery. It begins at the lower border of the teres major, as the upward continuation of the basilic vein of the arm, and it becomes the subclavian vein at the lateral margin of the first rib. At the lower margin of the subscapu- laris it receives the two vencz comites of the brachial artery, and above the level of the pectoralis minor it is joined by the AXILLARY SPACE 27 cephalic vein. Its other tributaries correspond, more or less closely, to the branches of the axillary artery. M. Subclavius.— The subclavius is a small muscle which lies immediately below the clavicle enclosed between the two layers of the costo-coracoid membrane. It takes origin by a short rounded tendon from the superior surface of the first costal arch, at the junction of the bone with the cartilage, and the fleshy belly is inserted into the shallow groove on the inferior surface of the clavicle. The nerve of Joint capsule Joint cavity Interarticular ligament Joint cavity Anterior chondro- sternal ligament FIG. 12. — Sterno-clavicular and Costo-sternal Joints. supply is derived from the fifth cervical nerve and enters the posterior surface of the muscle. When the muscle contracts it depresses the clavicle and draws it slightly forwards. Dissection. — When the subclavius has been examined it must be divided horizontally, and when this has been done the costo-clavicular ligament will be found behind the medial end of the muscle. The clavicle must now be detached from the sternum and the cartilage of the first rib, and turned laterally so that the brachial plexus may be properly examined, but before this is done the sterno-clavicular joint should be studied. With the assistance of the dissector of the head and neck the clavicular part of the sterno-cleidomastoideus muscle must be 28 THE UPPER EXTREMITY detached from the superior border of the clavicle and the sternal part of the muscle must be pulled towards the medial plane. Articulatio Sternoclavicularis. — The sterno-clavicular joint is a diarthrodial joint formed by the sternal end of the clavicle, the lateral part of the superior border of the manubrium sterni, and the superior surface of the sternal end of the cartilage of the first rib. It helps to increase the range of the forward, backward, and upward movements of the arm. The clavicle is attached to the sternum and the first rib by a strong fibrous capsule. Within the capsule is an articular meniscus which separates the joint cavity into two parts. It is attached to the superior border of the sternal end of the clavicle, to the superior surface of the first rib, and to the anterior and posterior parts of the capsule. On the lateral aspect of the capsule there is a strong accessory ligament, the costo-clavicular ligament, which lies behind the origin of the subclavius muscle and passes upwards, back- wards, and laterally from the first rib to the costal tubercle on the lower surface of the clavicle. In the capsule itself there are three thickened bands, an anterior, a posterior, and a superior, and as some of the fibres of the latter pass from one clavicle to the other, it is called the interclavicular ligament. Dissection. — Pull the sternal head of the sterno-cleidomastoid muscle towards the medial plane. Cut through the anterior part of the capsule of the joint close to the sternum. Pass the knife behind the capsule, avoid- ing the anterior jugular vein which runs laterally behind the upper border of the joint, and detach the fibres of origin of the sterno-hyoid muscle which spring from the back of the capsule. Cut through the posterior ligament and pull the clavicle laterally. The meniscus is now exposed. Detach it from the first rib, then carry the knife laterally below the clavicle and cut through the lower part of the capsule and the costo-clavicular ligament. The clavicle can now be displaced sufficiently upwards and laterally to bring the whole of the brachial plexus into view. Before studying the plexus, the dissector should note that behind the sterno- clavicular joint there are the lower fibres of the sterno-hyoid and sterno- thyreoid muscles which intervene on the right side between the capsule of the joint and the bifurcation of the innominate artery into its right common carotid and subclavian branches, and on the left side between the joint and the left common carotid artery. Plexus Brachialis (Brachial Plexus). — This important plexus is formed by the anterior primary divisions of the four lower cervical nerves and the greater part of the large anterior branch of the first thoracic nerve. Above, the plexus is further reinforced by a small twig of communication which passes from the fourth to the fifth cervical nerve, whilst below, AXILLARY SPACE 29 a similar connecting twig not infrequently passes upwards, in front of the neck of the second rib, from the second to the first thoracic nerve. The manner in which these great nerves join to form the plexus is very constant. The fifth and sixth Scalenus anterior and longus cc Scalenus medius and posterior -Phrenic nerve Seal. ant. and longus colli Seal. med. and post. Seal. ant. and longus colli Seal. med. and post. Scalenus ant. and longus colli Scalenus med. and post. T3 FIG. 13. — Diagram of the Brachial Plexus. (After Paterson.) cervical nerves unite to form an upper trunk ; the seventh remains single and proceeds distally as a middle trunk ; whilst the eighth and first thoracic nerves join, close to the intervertebral foramina, to constitute a third or lower trunk. A short distance above the clavicle each of the three trunks splits into an anterior and a posterior division. Raise the three anterior divisions on the handle of the knife, and it will be 30 THE UPPER EXTREMITY seen that all the three posterior divisions unite to form the posterior cord of the plexus, and, further, that the most medial of these divisions is much smaller than the other two. Of the three anterior divisions the two lateral join to constitute the lateral cord, whilst the medial passes distally by itself, as the medial cord of the plexus. From the three cords of the plexus are given off the branches which supply the upper extremity. From the above description it will be seen that the plexus may be divided into four stages : — First Stage, . . Five separate nerves (viz. four lower cervical and first thoracic). Second Stage, . Three nerve-trunks (viz. an upper, middle, and lower). Third Stage, . Three anterior divisions and three posterior divisions. Fourth Stage, . Three nerve -cords (viz. a lateral, medial, and a posterior). The plexus lies in the lower and medial part of the posterior triangle of the neck, behind the middle third of the clavicle, and in the axilla ; extending from the lateral border of the scalenus anterior to the lower border of the pectoralis minor. As a rule the first two stages are in the neck, the third stage is behind the clavicle, and the last stage is in the axilla. It has been customary to divide the branches of the plexus into supraclavicular and infraclavicular groups, but such a division is neither scientifically accurate nor practically important. The branches of the plexus spring either from its roots, or its trunks, or its cords. The parts of the plexus above the clavicle, and the branches given off in the supra- clavicular region, are found and cleaned by the dissector of the head and neck, and the remaining parts of the plexus and its branches are displayed by the dissector of the upper extremity, but the two dissectors must combine to examine thoroughly the general relations and the branches of the plexus. The Eelations of the Plexus.— Superficial to the cervical part of the plexus lie the skin, the superficial fascia, the platysma, the deep fascia, the external jugular vein, the transverse cervical and transverse scapular veins, the posterior belly of the omo-hyoid muscle, and the transverse cervical artery. Behind it is the scalenus medius muscle. In the interval between the neck and the axilla, the clavicle AXILLARY SPACE 31 and the transverse scapular artery and vein are in front of it ; and the third part of the subclavian artery is anterior to its lowest trunk. The scalenus medius is still behind it. In the axilla it has in front of it the integument, the fascia, the platysma, the pectoralis major, the pectoralis minor, the costo-coracoid membrane, the "cephalic vein, and the axillary artery; behind it lie the upper serration of the serratus anterior, the fascia-filled interval between the medial and posterior walls of the axilla, and the subscapularis muscle. The branches from the roots of the plexus are: (i) Branches to the scalenus anterior, the longus colli, the scalenus medius, and the scalenus posterior (from C. v., vi., VIL, VIIL). (2) A communication to the phrenic nerve (from C. v., or v. and vi.). (3) The dorsalis scapulae nerve which supplies the rhomboid muscles (from C. v.). (4) The long thoracic nerve which supplies the serratus anterior (from C. v., vi., VIL). The branches from the trunks of the plexus are : (i) The nerve to the subclavius from the upper trunk (from C. v., vi.). It has already been seen piercing the posterior surface of the costo-coracoid membrane and entering the posterior aspect of the subclavius (p. 27). (2) The suprascapular nerve from the upper trunk (from C. v., vi.). It will be found crossing the lower part of the posterior triangle • deep to the posterior belly of the omo-hyoid muscle, and disappearing through the suprascapular notch on its way to the dorsum scapulae. The branches from the cords are — From the lateral cord : Nervus thoracalis anterior lateralis (O.T. External Anterior Thoracic) (from C. v., vi., vir.). N. musculocutaneus (from C. v., vi., vn.). N. medianus, caput lateralis (O.T. Outer Head of Median) (from C. V., VI., VIL). From the medial cord : N. thoracalis anterior medialis (O.T. Internal Anterior Thoracic) (from C. VIIL, D. i.). N. cutaneus antibrachii medialis (O.T. Internal Cutaneous) (from C. VIIL, D. L). N. cutaneus brachii medialis (O.T. Lesser Internal Cutaneous) (from D. i. ). N. medianus, caput medialis (O.T. Inner Head of Median) (from C. VIIL, D. L). N. ulnaris (from C. VIIL, D. L). From the posterior cord : Nn. subscapulares (O.T. Upper and Lower) (from C. v., vi.). 32 THE UPPER EXTREMITY N. thoracodorsalis (O.T. Long Subscapular) (from C. vi., vn., VIII.). N. axillaris (O.T. Circumflex) (from C. v., vi.). N. radialis (O.T. Musculospiral) (from C. v., vi., vn., vin. i). In the above table the different spinal nerves from which the fibres of the several branches are derived are indicated. Nervi Thoracales Anteriores (Anterior Thoracic Nerves).— These are the nerves which supply the pectoral muscles. They are two in number, the lateral and the medial. The lateral springs from the lateral cord of the plexus, passes forwards across the lateral side of the first part of the axillary artery, anastomoses in front of the artery with the medial nerve, pierces the costo-coracoid membrane, and breaks up into branches which end in the pectoralis major. The medial anterior thoracic nerve is somewhat smaller than its lateral companion. It springs from the medial cord of the plexus, passes forwards between the axillary artery and vein, anasto- moses in front of the artery with the lateral nerve, gives twigs of supply to the pectoralis minor, then pierces that muscle and ends in the pectoralis major which it also supplies. The pectoralis major is, therefore, supplied by both anterior thoracic nerves, the pectoralis minor by the medial nerve alone. Nervi Subscapulares (Subscapular Nerves). — The sub- scapular nerves are also two in number — the upper and the lower. They both spring from the posterior cord of the plexus. After a very short course the upper nerve sinks into the upper and posterior part of the subscapularis which it supplies. The lower Subscapular nerve passes downwards and laterally, gives branches to supply the lower part of the subscapularis, then passes through the angle between the Subscapular artery and its circumflex scapulae branch and ends in the teres major which it supplies. Nervus Thoracodorsalis (O.T. Long Subscapular Nerve).— This nerve springs from the posterior cord of the plexus, passes obliquely downwards and laterally, through the axilla, and joins the Subscapular artery near the lower part of the lateral border of the subscapularis muscle. After crossing in front of the artery it terminates in the latissimus dorsi which it supplies. Nervus Thoracalis Longus (O.T. Posterior Thoracic or External Respiratory Nerve of Bell). — The long thoracic nerve may now be studied in its whole length. It passes AXILLARY SPACE 33 downwards on the lateral surface of the serratus anterior and is the nerve of supply to that muscle. It arises in the root of the neck, from the brachial plexus, by three roots. The upper two roots (one from the fifth cervical and the other from the sixth cervical nerve) pierce the scalenus medius, and uniting ^.^.M. scalenus medius \l M. scalenus anterior Upper part of M. serratus anterior Middle portion of M. serratus anterior M. obliquus externus FIG. 14. — Serratus anterior muscle and origin of the external oblique muscle ; the scapula is drawn away from the side of the chest. into one stem give off branches to the upper part of the serratus anterior. The third root takes origin from the seventh cervical nerve, passes in front of the scalenus medius, and runs downwards for a considerable distance on the surface of the serratus anterior, before it unites with the other part of the nerve. The entire nerve, thus formed, can be followed to the lower part of the serratus, giving twigs to each of its digitations. VOL. i — 3 34 THE UPPER EXTREMITY M. Serratus Anterior (O.T. Serratus Magnus). — The serratus anterior arises by fleshy digitations from the upper eight ribs, about midway between their angles and cartilages. Mm. Cqraco- brachialis and Biceps brachii (cap. brev.) M. Pectoralis minor M. Omohyoideus M. Triceps (cap. long.) FIG. 15.— Costal aspect of the Scapula with the Attachments of Muscles mapped out. The slips are arranged on the chest wall so as to present a gentle curve convex forwards. The lower three interdigitate with the external oblique muscle of the abdomen. The serratus anterior is inserted into the entire length of the anterior lip of the vertebral border of the scapula, and it falls AXILLARY SPACE 35 naturally into three parts, (a) The upper part, composed of the large first digitation alone, arises from the first and second ribs, and from a tendinous arch between them. The fibres converge, to be inserted into a somewhat triangular surface on the costal aspect of the medial angle of the scapula, (b) The middle part consists of two digitations which take origin from the second and third ribs. The upper slip is very broad, and springs from the lower border of the second rib. The fibres diverge to form a thin muscular sheet, which is inserted into the anterior lip of the vertebral border of the scapula, between the insertions of the upper and lower portions, (c) The lower part is formed by the remaining digitations of the muscle. These converge to form a thick mass, which is inserted into a rough surface upon the costal aspect of the inferior angle of the scapula. The deep surface of the serratus anterior is in contact with the chest wall. It is the most powerful protractor of the upper extremity. Dissection. — At the end of the fifth day, after the dissector has examined the serratus anterior and carefully revised the contents of the axilla he must replace the clavicle, pack the axilla with tow or rags steeped with disinfectant solution and fix the skin flaps to the wall of the thorax with a few stitches. When he returns on the sixth day he will find that the body has been placed upon its face, with blocks supporting the chest and the pelvis. It will remain in this position for five days, and during the first two of these the dis- sector of the upper extremity must examine the structures which connect the limb with the posterior aspect of the trunk. Surface Anatomy. — In the middle line of the back there is little difficulty in recognising the tips of the spinous processes of the vertebrae. These follow each other in consecutive order, and it may be observed, when the finger is passed over them, that all of them do not lie in the medial plane : some may be deflected, in a slight degree, to one side or the other. The spines of the vertebrae are the only parts of the vertebral column which come to the surface ; they alone yield direct information, by touch, to the surgeon as to the condition of the spine. At the lower end of the neck, the spine of the seventh cervical vertebra (vertebra prominens) makes a visible projection ; and the spines of the first two thoracic vertebras are likewise very prominent. As a rule, the most evident of the three is that of the first thoracic vertebra. At a lower level, in subjects of good muscular development, a median furrow is produced by the prominence of the sacrospinalis muscle on each side, and i— 3 « 36 THE UPPER EXTREMITY the spines of the vertebrae may be felt at the bottom of Ext. occip. protub. Mastoid process - Spine of scapuh Acromion Inf. angle of scapula |_ Post. sup. spine of ilium Tip of coccy Great trochanter Tuberosity of ischium Medial condyle of femurl Lateral condyle of femur J Lateral condyle of tibia Head of fibula Medial epicondyle Olecranon Head of radius Styloid process of ulna Styloid process of radius FIG. 1 6. — Surface View showing incision and bony points. the groove. The furrow attains its greatest depth in the DISSECTION OF THE BODY 37 upper part of the lumbar region, and it fades away below at the level of the spine of the third sacral vertebra. The finger should next be passed along the crest of the ilium as it pursues its sigmoid course forwards and laterally. The highest point of the iliac crest corresponds in level with the spine of the fourth lumbar vertebra, and the posterior superior spine of the ilium can be easily detected, seeing that its position is indicated by a small but distinct depression or dimple on a level with the second sacral spine. The scapula or shoulder blade is for the most part thickly covered by muscles ; but, in spite of this, its general outline can be made out. It covers a considerable area of the upper portion of the posterior aspect of the thorax. With the hand by the side its medial angle lies over the second rib, the root of its spine is placed opposite the spine of the third thoracic vertebra, whilst its inferior angle reaches down as far as the seventh, or even the eighth, rib. The scapula is very mobile, and moves to a greater or less degree with every movement of the limb. The spine and acromion of the scapula are subcutaneous throughout. Below the scapula the lower five ribs can be felt, and the tip of the last rib can be made out at a point about two inches above the iliac crest. DISSECTION OF THE BACK. In this dissection the following are the parts which require to be examined :— 1. The cutaneous vessels and nerves of the back. } 2. The m. trapezius. >• ist day. 3. The m. latissimus dorsi. 4. The mm. rhomboidei and their nerves. 5. The m. levator scapulae. 6. The n. accessorius and the nerves from the cervical plexus which supply the trapezius. 7. The a. transversa colli and its two terminal branches (viz. the 2nd day* ramus descendens and the ramus ascendens). 8. The posterior belly of the m. omo-hyoideus. 9. The a. transversa scapulae and n. suprascapularis. This dissection must be completed in two days, in order that the dissector of the head and neck may be enabled to con- tinue the deeper dissection of the back. Theyfctf day's work 38 THE UPPER EXTREMITY should comprise — (i) the reflection of the skin; (2) the dissection of the cutaneous nerves and vessels; and (3) the cleaning of the latissimus dorsi and trapezius muscles. The remainder of the dissection can be undertaken on the second day. Reflection of the Skin.— The following incisions are necessary: — i. From the tip of the coccyx upwards, along the middle line of the body, to the spine of the seventh cervical vertebra. 2. From the upper end of the foregoing medial incision transversely, to the tip of the acromion of the scapula. 3. From the lower extremity of the median incision in a curved direction laterally and forwards, along the crest of the ilium, to within two inches of the anterior superior iliac spine. 4. An oblique incision from the spine of the first lumbar vertebra, upwards and laterally, to the posterior fold of the axilla, and along the latter to the arm. The two large flaps which are now mapped out upon the back must be carefully raised from the subjacent fatty tissue. Reflect the upper triangular flap first, and then the lower flap. Panniculus Adiposus (Superficial Fascia). — In subjects which have been allowed to lie for some time on the back the superficial fascia is usually more or less infiltrated with fluid which has gravitated into its meshes, otherwise it has the ordinary characters of superficial fascia (p. 5). Dissection. — In searching for the cutaneous nerves cut boldly down through the superficial fascia, in the direction in which the nerves run (Fig. 17), until the plane is reached at which the superficial and deep fascia blend. It is here that the main trunks are to be found and in a well injected subject the cutaneous arteries will serve as guides. A more rapid way of finding the cutaneous nerves in this region is to reflect the superficial and deep fascia laterally from the vertebral spines in one layer ; the nerves are then found as they issue from the muscles. This plan, however, should only be adopted by the senior student. Vasa Cutanea, Nervi Cutanei (Cutaneous Vessels and Nerves). — The cutaneous nerves of the back are derived from the posterior branches of the spinal nerves. As the posterior branches pass backwards, they subdivide into medial and lateral divisions. Both of these supply twigs to the muscles amongst which they lie ; but one or the other also contains some sensory fibres which come to the surface, in the shape of a cutaneous nerve, to supply the skin. In the thoracic region the upper six or seven cutaneous nerves are the terminations of the medial branches of the posterior rami of the thoracic nerves. They become super- ficial close to the vertebral spines, and are to be sought for near the median plane. It is not uncommon to find one or more of them piercing the trapezius one or two inches DISSECTION OF THE BACK 39 lateral to the line of emergence of the others. The branch which comes from the second thoracic nerve is the largest of the series; and it may be traced laterally towards the shoulder, Great occipital nerve Third occipital nerve Sterno-mastoid Small occipital nerve Trapezius Semispinalis cervicis (O.T. complexus) Splenius capitis Cervical nerves to trapezius Accessory nerve Ascending br. of transverse cervica Levator scapulae Descending br. of tr; cervical artery and r to rhomboids Rhomboideus mi Trapezius (reflected) Rhomboideus major Teres major Serratus anter Serratus posterior inferior Latissimus dorsi External oblique muscle Trigonum Petiti Glutaeus medius Glutajus maximus FIG. 17. — Dissection of the Superficial Muscles and Nerves of the Back. across the spine of the scapula. The lower five or six cutaneous nerves in the thoracic region are the terminal twigs of the lateral branches of the posterior rami of the thoracic nerves; and, consequently, they must be looked for at a short distance from the middle line of the back. They reach the surface by piercing the latissimus dorsi muscle on the i— 3c External branches of posterior divisions of lumbar nerves 40 THE UPPER EXTREMITY line of the angles of the ribs and the lateral margin of the sacrospinalis muscle. In every case the cutaneous branches derived from the thoracic nerves turn laterally in the super- ficial fascia, and may be traced for a varying distance in this direction. It is important to note that the area of skin supplied by each of these cutaneous nerves is placed at a lower level than the origin of the posterior branches from which it arises. In the lumbar region three cutaneous nerves reach the surface by piercing the lumbar fascia at the lateral margin of the sacrospinalis muscle, a short distance above the ilium. They are the terminal twigs of the lateral branches of the posterior rami of the' three upper lumbar spinal nerves ; and they differ from those above, inasmuch as they turn downwards over the crest of the ilium to supply the skin of the gluteal region (Fig. 17). The cutaneous arteries which accompany these nerves come from the posterior branches of the intercostal and lumbar arteries. Muscles connecting the Limb to the Dorsal Aspect of the Trunk. — These are five in number, and are arranged in two strata. Two form the superficial stratum, viz. the trapezius and the latissimus dorsi. Both are broad, flat muscles which cover the greater part of the dorsal aspect of the trunk, from the occiput above to the ilium below. The trapezius lies over the back of the neck and the thorax. The latissimus dorsi is placed lower down. The deeper stratum of muscles, composed of the levator scapulae and the two rhomboid muscles, is placed under cover of the trapezius. Dissection. — The trapezius should now be cleaned. This muscle belongs only in part to the dissector of the upper extremity. The portion of it which lies above the prominent spine of the seventh cervical vertebra is the property of the dissector of the head and neck, and must be dissected by him. The two dissectors should work in conjunction with each other ; and when the entire muscle is exposed, each should give the other an opportunity of studying it in its entirety. In cleaning the trapezius the limb must be placed in such a position as will render the fibres of the muscle tense. If the dissection is being made on the right side, the arm must be placed close to the trunk, and drawn downwards, whilst the scapula is dragged well forwards over the end of the block which supports the thorax. A transverse cut is now to be made through the superficial and deep fasciae, from the seventh cervical spine laterally. This incision will be found to coincide with the direction of the fibres of the muscle at this level. From this point work gradually downwards, raising both fasciae in a continuous layer from the surface of DISSECTION OF THE BACK 41 the muscle. The knife must always be carried in the direction of the muscular fibres : and care must be taken to leave none of the thin, filmy deep fascia behind. As the direction of the fibres changes the position of the arm must also be changed to keep the fibres which are being cleaned on the stretch. In the case of the left trapez^^^s, the student must make the incision through the fascia, along the lower margin of the muscle, and work upwards to the level of the seventh cervical vertebra. In removing the fascia from the trapezius, and indeed throughout the whole dissection of the back, the cutaneous nerves must be carefully preserved, in order that the dissector of the head and neck may have an opportunity of establishing their continuity with the trunks from which they arise. M. Trapezius. — The trapezius is a flat, triangular muscle, which lies, in its entire extent, immediately subjacent to the deep fascia. It has a very long origin, which extends along the median plane, from the occiput above to the level of the last dorsal vertebra below. It arises from — (i) the medial FIG. 18. — Upper Surface of the Right Clavicle. third or less of the superior nuchal line of the occipital bone and the external occipital protuberance ; (2) the ligamentum nuchae and the spine of the seventh cervical vertebra ; (3) the tips of the spines of all the thoracic vertebrae, as well as the supraspinous ligaments which bridge across the intervals between them (Fig. 17). In the lower cervical and upper thoracic regions the tendinous fibres by which the muscle arises lengthen out so as to form a flat tendon, which, taken in conjunction with the corresponding aponeurosis of the opposite side, exhibits an oval outline. As the fibres of the trapezius pass laterally they converge, to gain an insertion into the two bones of the shoulder-girdle. The occipital and upper cervical fibres incline downwards, and, turning forwards over the shoulder, are inserted into the lateral third of the posterior border of the clavicle (Fig. 1 8) ; the lower cervical and upper thoracic fibres pass more or less trans- versely to gain an insertion into the medial border of 42 THE UPPER EXTREMITY the acromion and the upper margin of the spine of the scapula ; while the lower thoracic fibres are directed upwards and, at the base of the scapula, end in a flat, triangular tendon, which plays over the smooth surface at the root of the scapular spine, and is inserted into a rough tubercle on the spine of the scapula immediately beyond this (Fig. 24, p. 55). To facilitate the movement of the tendon upon the bone a small bursa mucosa is interposed between them. The trapezius is supplied by the accessory nerve and by twigs from the third and fourth cervical nerves. It is an elevator and depressor of the shoulders, and an adductor of the scapula. Dissection. — The latissimus dorsi is now to be dissected. It is a difficult muscle to clean, not only on account of the varying direction of its fibres, but also because its upper part is generally very thin, and its upper border ill -defined. Near the spines of the vertebrae its upper portion is overlapped by the trapezius, but in the greater part of its extent it is subcutaneous. Both layers of fascia should be raised at the same time from its surface, and its fibres may be stretched by raising the arm and folding it under the neck. The origin of the latissimus dorsi in the lumbar region is effected through the medium of the superficial lamina of the lumbar fascia, a dense tendinous aponeurosis, which covers the sacrospinalis in the loins (Fig. 19). Clean this structure thoroughly. The attachment of the muscle to the crest of the ilium, and its slips of origin from the lower ribs, -must be carefully defined ; at the same time, the posterior and lower part of the external oblique muscle of the abdomen should be cleaned, so that its relation to the latissimus dorsi may be studied. As the latissimus dorsi sweeps over the inferior angle of the scapula it receives an accession of fibres from that bone. This fleshy slip may be brought into view, when the muscle is cleaned, by relieving the tension of the muscular fibres, and then turning the upper margin of the muscle laterally. The slip in question is apt to be mistaken for a piece of the teres major muscle upon which it lies. M. Latissimus Dorsi. — The latissimus dorsi is a wide, flat muscle, which covers the back from the level of the sixth thoracic vertebra down to the crest of the ilium (Fig. 1 7, p. 39). It arises — (i) from the tips of the spinous processes of the lower six thoracic vertebrae and the supraspinous ligaments in connection with them; (2) from the superficial lamella of the fascia lumborum (Fig. 19); (3) by a thin tendinous origin from a small extent of the lateral lip of the crest of the ilium in front of the fascia lumborum (Fig. 143, p. 385); (4) by three or four digitations from the lower three or four ribs ; and (5) by a fleshy slip from the dorsal aspect of the inferior angle of the scapula (Fig. 24, p. 55). By means of its origin from the posterior lamella of lumbar fascia, it receives an indirect attachment to the spines of the lumbar and upper sacral DISSECTION OF THE BACK 43 vertebrae, and also to the posterior part of the crest of the ilium. The costal slips of origin interdigitate with the lower digitations of the external oblique muscle of the abdominal wall. The fibres of the latissimus dorsi converge rapidly as they approach the lower part of the scapula. The highest fibres pass almost horizontally towards this point ; the lowest fibres ascend almost vertically ; whilst the intermediate FIG. 19. — Diagram of the Lumbar Fascia. 1. Serratus posterior inferior. 2. Latissimus dorsi. 3. Transversus abdominis. 4. Obliquus internus. 5. Obliquus externus. 6. Fascia transversalis. 7. Sacrospinalis. 8. Quadratus lumborum. 9. Psoas major. fibres show varying degrees of obliquity. As a result of this convergence of fibres, the muscle is greatly reduced in width ; and it sweeps over the inferior angle of the scapula in the form of a thick, fleshy band, which winds round the lower margin of the teres major muscle to gain insertion, by means of a narrow, flat tendon, into the floor of the intertubercular sulcus of the humerus (Fig. 33, p. 79). This insertion cannot be studied at present, but will be seen later on. With the teres major muscle the latissimus dorsi forms the posterior fold of the axilla. At first it is placed on the dorsal aspect of 44 THE UPPER EXTREMITY the teres major, then it is folded round its distal border, and finally it is inserted in front of it. To this peculiar relation- ship of the two muscles is due the full, rounded appearance of the posterior axillary fold. The latissimus dorsi is supplied by the thoracodorsal nerve. It is an adductor, retractor, and medial rotator of the upper extremity. Two Intermuscular Spaces. — A triangular space mapped out by the distal border of the trapezius, the proximal border of the latissimus dorsi, and the base of the scapula, will now be noticed (Fig. 22, p. 53). Within these limits a small portion of the rhomboideus major can be seen, and also a varying amount of the wall of the thorax — a part corresponding to the sixth intercostal space and the borders of the ribs which bound it above and below. It is well to note that this is the only part of the thoracic parietes on the posterior aspect of the trunk which is uncovered by muscles. Further, between the last rib and the crest of the ilium the anterior border of the latissimus dorsi will generally be observed to overlap the posterior border of the external oblique muscle of the abdominal wall. Sometimes, however, a narrow triangular interval exists between the two muscles, in which is seen a small part of the internal oblique muscle. This space is termed the trigonum lumbale (Petiti) (Fig. 17, p. 39). Reflection of the Trapezius.— On the second day the dissector should begin by reflecting the trapezius, working, if possible, in conjunction with the dissector of the head and neck. Divide the muscle about two inches from the spines of the vertebrae, and throw it laterally towards its insertion. The trapezius is very thin at its origin, and the greatest care must therefore be taken not to injure the subjacent rhomboid muscles. The small bursa between the tendon of insertion of the lower part of the trapezius and the triangular root of the spine of the scapula must not be overlooked. Nerves and Vessels of Supply to the Trapezius. — A dis- section of the deep surface of the reflected muscle will reveal the following structures : — a. The accessory nerve. b. Two or three nerves from the cervical plexus. c. The ascending branch of the transverse cervical artery. These constitute the nervous and vascular supply of the trapezius. The nerves have already been displayed by the dissector of DISSECTION OF THE BACK 45 the head and neck, as they cross the posterior triangle of the neck. The branches from the cervical plexus come from the third and fourth cervical nerves. On the deep surface of the trapezius they join with branches of the accessory nerve to form the subtrapezial plexus, from which twigs proceed into the substance of the muscle. The terminal twig of the accessory nerve can be traced nearly to the lower margin of the trapezius. The ascending branch of the transverse cervical artery, which accompanies the accessory nerve, must be followed to the anterior border of the trapezius, where it will be seen to spring from the trunk of the artery. Dissection. — The posterior belly of the omo-hyoid, the transverse scapular artery, and suprascapular nerve can now be displayed by dis- secting towards the upper margin of the scapula, and removing carefully, the loose fatty tissue in this locality. The dissector of the head and neck must take part in this dissection. M. Omo-hyoideus. — -Arteria Transversa Scapulae (O.T. Suprascapular Artery) and N. Suprascapularis (Supra- scapular Nerve). — The slender posterior belly of the omo-hyoid muscle will be seen to arise from the upper border of the scapula immediately medial to the incisura scapulae. It also derives fibres from the ligament which bridges across this notch. It is supplied by a twig from the ansa hypoglossi. The transverse scapular artery will be noticed to enter the supra- spinous fossa of the scapula by passing over the superior transverse scapular ligament, whilst the suprascapular nerve proceeds into the fossa under cover of that ligament. Dissection. — Draw the scapula well over the edge of the block which supports the thorax of the subject. The two rhomboid muscles are thus rendered tense, and the cleaning of their fleshy fasciculi greatly facilitated. The dorsalis scapuke nerve should be secured at this stage, so that it may be preserved from injury in the further dissection of the region. It can best be detected by dissecting in the interval between the rhomboideus minor and the levator scapulae about one inch to the medial side of the medial angle of the scapula (Fig. 17, p. 39). It is accompanied by the descending branch of the transverse cervical artery, and it will afterwards be traced upon the deep surface of the rhomboid muscles when they are reflected. Mm. Rhomboidei. — The two rhomboid muscles constitute a thin quadrangular sheet of muscular fibres, which proceeds from the spinous processes of the vertebrae to the base of the scapula. 46 THE UPPER EXTREMITY The rhomboideus minor is a narrow, ribbon -like fleshy band which runs parallel to the upper border of the major rhomboid. It springs from the lower part of the ligamentum nuchae, the spine of the seventh cervical vertebra, and frequently also from the spine of the first thoracic vertebrae. It is in- serted into the base of the scapula opposite the triangular surface at the root of its spine (Fig. 24, p. 55). It is entirely covered by the trapezius. The rhomboideus major arises from the upper four or five thoracic spines, and the corresponding parts of the supraspinous ligaments. Its fibres run obliquely downwards and laterally, and end in a tendinous cord, which receives insertion into the base of the scapula close to the inferior angle. From this point, up to the commencement of the spine, the tendinous cord is firmly bound to the base of the scapula by areolar tissue (Fig. 24, p. 55). The greater part of the rhomboideus major is covered by the trapezius ; only a small portion near the inferior angle of the scapula lies immediately subjacent to the deep fascia. M. Levator Scapulas (O.T. Levator Anguli Scapulae).— This is an elongated muscle which arises by four more or less tendinous slips from the posterior tubercles of the transverse processes of the upper four cervical vertebrae, and passes downwards and backwards to be inserted into the base of the scapula from the medial angle to the spine. It is supplied by branches from the third and fourth cervical nerves. Dissection. — In cleaning the levator scapulae muscle care must be taken of the nerves which pass to it from the cervical plexus, and also of the dorsalis scapulae nerve and the descending branch of the transverse cervical artery which lie under cover of it near the base of the scapula. The dissector of the head and neck has an interest in the levator scapulae, and when it has been studied by both dissectors it should be divided midway between its origin and insertion, and the lower portion should be turned laterally. The dorsalis scapulae nerve has already been secured in the interval between the rhomboideus minor and the levator scapulae, and it has still further been exposed by the reflection of the latter muscle. It may now be displayed in its whole length, together with the descending branch of the transverse cervical artery, which it accompanies, by reflecting the rhomboidei muscles. These should be detached from the ligamentum nuchae and the vertebral spines, and be thrown laterally towards the base of the scapula. In doing this care must be taken of the serratus posterior superior, a thin muscle which lies subjacent, and is apt to be injured. Nervus Dorsalis Scapulae (O.T. Nerve to the Rhomboids).— This is a long slender twig which arises in the neck from the fifth cervical nerve, usually in common with the upper root DISSECTION OF THE BACK 4? of the long thoracic nerve. It pierces the scalenus medius, and then proceeds downwards, under cover of the levator scapulae, to the deep surface of the rhomboidei muscles to which it is distributed. The dorsalis scapulae nerve likewise supplies one or two twigs to the levator scapulae. The dorsalis scapulae nerve sometimes pierces the levator scapulae in two or more branches, which unite in a plexi- form manner. Ramus Descendens of the Art. Transversa Colli (O.T. Posterior Scapular Artery). — The descending branch of the transverse cervical artery takes origin in the lower part of the neck close to the lateral margin of the levator scapulae. At first it proceeds medially under cover of this muscle, but soon changing its direction it runs downwards along the base or vertebral border of the scapula under cover of the rhomboid muscles (Fig. 17, p. 39). It gives numerous branches to both costal and dorsal aspects of the scapula, and its terminal twigs may enter the latissimus dorsi. One large branch usually passes backwards, in the interval between the rhomboid muscles or through the greater rhomboid, to reach the trapezius muscle ; and another branch, the supraspinal, is given to the supraspinatus muscle, and the structures superficial to it. Reflection of Latissimus Dorsi. — Divide the muscle by carrying the knife from its upper margin, about three inches from the vertebral spinesj obliquely downwards to a point a little way behind its digitation from the last rib. In raising the medial portion of the muscle care must be taken of the subjacent serratus posterior inferior. The attachment of the latissimus dorsi to the crest of the ilium and to the lumbar aponeurosis can now be verified. The lateral part of the muscle is next to be thrown forwards, so that the three costal digitations may be seen from their deep aspect, and also for the purpose of displaying the termination of the sub- scapular artery and the thoracodorsal nerve. These are found upon the deep surface of the muscle at the inferior angle of the scapula. The Removal of the Upper Extremity. — After the costal attachments of the latissimus dorsi have been displayed the upper extremity must be removed. Draw the extremity away from the body ; detach the costal slips of the latissimus, cut through the serratus anterior about one inch from the vertebral border of the scapula ; divide the dorsal scapular nerve, the ramus descendens of the transverse cervical artery, the posterior belly of the omo-hyoid muscle, the transverse scapular artery and the suprascapular nerve. Cut through the axillary vessels and the cords of the brachial plexus at the lateral border of the first rib ; detach the anterior skin flap 48 THE UPPER EXTREMITY from the anterior wall of the thorax and take the extremity to a separate table for further dissection. SHOULDER— SCAPULAR REGION. In the dissection of this region the following parts must be studied : — 1. Cutaneous nerves of the shoulder. 2. Deep fascia. 3. Deltoid muscle. 4. Sub-acromial bursa. 5. Anterior and posterior circumflex vessels of the humerus. 6. Axillary (circumflex) nerve. 7. Circumflex scapular artery. 8. Subscapularis muscle. 9. Supraspinatus, infraspinatus, teres minor, and teres major muscles. 10. Bursse in connection with the shoulder -joint. 11. Suprascapular nerve and transversa colli artery. 12. Acromio-clavicular joint, and the coraco-acromial arch. Muscles inserted into the Clavicle and Scapula. — The insertions of the muscles which have already been divided should first engage the attention of the student. They should be carefully defined and the precise extent of each studied. Begin with the orno - hyoid, which springs from the superior border of the scapula ; then deal in the same way with the levator scapula, rhomboideus minor and major, which are attached to the vertebral border of the bone, and the serratus anterior, which is inserted into the costal aspect of the medial and inferior angles, and the intervening portion of the vertebral border of the scapula. The insertion of the pectoralis minor into the coracoid process, and of the trapeziits into both clavicle and scapula, should also be thoroughly ex- amined. When this has been done these divided muscles may be removed, with the exception of about half an inch of each, which it is advisable to leave attached to the bones for future reference. Dissection. — A block should now be placed in the axilla, and the skin removed from the upper and lateral aspects of the shoulder as low down as the insertion of the deltoid. Commence in front and proceed from before backwards, taking care to leave the fatty superficial fascia in its place. Nervi Cutanei (Cutaneous Nerves). — In the superficial fascia, which is thus laid bare, cutaneous nerves from two different sources must be secured and traced, in order that the area of skin supplied by each may be recognised. They are : — 1. Posterior supraclavicular nerves from the third and fourth cervical nerves. 2. Cutaneous branches from the axillary nerve (circumflex). The posterior supraclavicular nerves have already been observed crossing the lateral third of the clavicle and the insertion of the trapezius under cover of the platysma. They have been divided in removing the limb. If the cut SHOULDER— SCAPULAR REGION 49 ends be secured and followed, they will be found to spread out over the lateral and posterior part of the upper portion of the deltoid region. Lateral end of clavicle Margin of acromion process Pectoralis major Cephalic vein Deltoid Cutaneous branches of axillary (O.T. circumflex) nerve piercing deltoid Lateral brachial cutaneous branch of axillary (O.T. circumflex) nerve Biceps Lateral head of triceps Brachialis Upper branch of dorsal cutaneous nerve of forearm ffif Cephalic vein Lower branch of dorsal cutaneous nerve of forearm Brachioradialis Tendon of triceps Olecranon Extensor carpi radialis longus FIG. 20. — The Deltoid Muscle and the lateral aspect of the Arm. The cutaneous branches of the axillary nerve consist — (a) of a large branch which turns round the posterior border of the deltoid muscle, the lateral brachial cutaneous nerve, VOL. 1—4 50 THE UPPER EXTREMITY and (£) of several fine filaments which pierce the substance of the deltoid muscle, and appear at irregular intervals on its surface. The latter are difficult to secure, but the main branch can be easily found by carefully dividing the superficial fascia along the posterior border of the deltoid. On everting this border very little dissection is required to expose the nerve hooking round it about two and a half inches above the insertion of the deltoid (Fig. 22). It breaks up into branches which supply the skin over the lower portion of the deltoid region. Deep Fascia. — A firm but thin fascia covers the subscapu- laris muscle. Into this some of the fibres of the serratus anterior are usually inserted at the vertebral border of the scapula. The strongest and most conspicuous fascia in this region is that which covers the exposed part of the infraspinatus muscle on the dorsal aspect of the scapula. It is firmly attached to the limits of the fossa in which that muscle lies, and presents other very apparent connections. Thus a strong septum, proceeding from its deep surface, will be noticed to dip in between the infraspinatus and teres minor muscles, and then, as it proceeds forwards, it gives a thin covering to the teres minor, teres major, and the deltoid. In- deed, it may be said to split into two lamellae — a superficial and a deep, — which as they pass forwards enclose between them the deltoid muscle. Dissection. — Depress the scapula and retain it in this position by means of hooks. The fibres of the deltoid are thus rendered tense, and the coarse fasciculi of the muscle may be cleaned. M. Deltoideus. — The deltoid muscle, as its name implies, is triangular in form. It is composed of coarse fasciculi, and covers the shoulder-joint. It arises from the anterior border of the lateral third or half of the clavicle (Fig. 18, p. 41), from the lateral border of the acromion and from the lower border of the spine of the scapula (Fig. 24, p. 55). Its origin closely corresponds with the insertion of the trapezius. The fasciculi of which the muscle is formed converge rapidly as they are traced distally, and finally they are attached, by a pointed tendinous insertion, to the deltoid eminence on the middle of the lateral surface of the body of the humerus (Fig. 33, p. 79). Its nerves of supply come from the axillary (circumflex) nerve. SHOULDER— SCAPULAR REGION 51 Dissection. — The limb should now be placed on its posterior aspect, and the posterior circumflex artery of the humerus and the axillary nerve should be traced backwards through the quadrilateral space. The bound- aries of the space should be defined and 'cleaned at the same time. Quadrilateral and Triangular Spaces. — The quadrilateral space is purely the result of dissection ; it has no real Cot Descending branch of transverse cervical artery Suprascapular nerve and transverse , scapular artery jracoid process Capsule of shoulder-joint Tendon of supraspinatus Tendon of infra- spinatus Subscapular artery Descending branch Circumflex scapulse artery Posterior circumflex artery and axillary nerve Nerve to teres. -minor FIG. 21. — Dissection of the Posterior Scapular Region. existence until the parts are artificially separated from each other. When viewed from the front, the boundaries will be seen to be formed — (a) laterally, by the upper part of the body of the humerus ; (b) medially, by the long head of the triceps ; (c] above, by the lower margin of the subscapularis ; (d) and below, by the upper border of the teres major. When viewed from behind, the upper boundary of the quadrilateral space will be seen to be formed by the teres minor ; the i— 4 a 52 THE UPPER EXTREMITY other boundaries are the same as those seen from the front. The term triangular space is the name given to another intermuscular interval which becomes apparent when the muscles in this region are cleaned and separated. It is placed nearer the inferior angle of the scapula, and the long head of the triceps intervenes between it and the quadrilateral space. It is bounded above by the subscapularis ; below by the teres major; and laterally by the long head of the triceps. The circumflex artery of the scapula should be followed into this space, and cleaned up to the point where it dis- appears around the axillary border of the scapula under cover of the teres minor. Dissection. — Having now traced the posterior circumflex artery of the humerus and the axillary nerve as far as possible, through the quadrilateral space, the position of the limb should be reversed. Turn it so that its dorsal surface is uppermost, and, everting slightly the posterior border of the deltoid, define the boundaries of the space as they are seen from behind. At the same time clean the circumflex vessels and the axillary nerve as they issue from the space to reach the deep surface of the deltoid muscle. Care must be taken not to injure the branch which the axillary nerve gives to the teres minor. The deltoid muscle may now be divided close to its origin and thrown downwards ; in doing this preserve the acromial branch of the thoraco- acromial artery which runs in the line of incision beneath the deltoid. A large bursa which lies between the deltoid and upper aspect of the capsule of the shoulder-joint must also be kept intact. Parts under cover of the Deltoid. — The deltoid covers the upper part of the humerus, and is wrapped round 'the shoulder-joint so as to envelop it behind, laterally, and in front. The full rounded appearance of the shoulder will now be seen to be due to the muscle passing over the expanded proximal end of the humerus. When the head of the bone is displaced the muscle passes more or less vertically downwards from its origin, and the dislocation is recognised by the squareness or flatness of the shoulder. Behind, the deltoid covers the muscles which arise from the dorsal aspect of the scapula as they pass laterally to reach the great tubercle of the humerus ; in front, it covers the upper part of the biceps muscle, and overlaps the coracoid process and the muscles attached to it. In relation also to the deep surface of the deltoid are the circumflex vessels of the humerus and axillary nerve. Bursa Subacromialis (Subacromial Bursa). — This is a large bursal sac which intervenes between the acromion and deltoid above, and the upper aspect of the capsule of the shoulder- joint below. It facilitates the play of the proximal end of the humerus, with its capsule, on the under aspect of the acromion and deltoid. Pinch a portion of it up with the SHOULDER— SCAPULAR REGION 53 forceps and make an incision into it.1 The finger may then be introduced into its interior to explore its extent and con- Spine of scapula A. trans, scapulae (O. T. suprascapulai) , M. supraspinatus M. infraspinatu* --,', <. A. circumflex scap. , (O.T. dorsalis scap. M. teres minor M. subscapularisy— M. teres major Triang. space -• Quadrangular space M. triceps cap. long. N. radialis (O.T. musculo-spiratt ' AMbrachiali N. suprascapularis M. deltoideus M. triceps cap. lat. N. to m. triceps, cap. med. Bursa subacromalis M. triceps, cap. med. -f N. ulnaris Epicond. med. N. flex. carp. uln. Olecranon FIG. 22. — Back of the Arm. inlraspinatus Capsular artic. Articulat. humeri ; N. to m. teres minor M. deltoideus N. axillaris (O.T. circumflex) ram. sup. N. axillaris, " am. inf. N. cutan. brach. — lat. .-- M. triceps, cap. lat. N. radialis (O.T. musculo-spiral) A. prof, brachii ram. ant. A. prof, brachii ram. post. N. cut. antib. dorsalis M. brachialis Epicond. lat. A. inteross. recurr. M. anconaeus Mm. ext. dig. comm. etdig. quint. M. ext. carp uJnaiis nections. In some cases it is divided by internal partitions into two or more chambers or loculi. 1 If the wall of the bursa be quite entire a blowpipe may be thrust into it. It can then be distended, and if unilocular it may be inflated to about the size of a hen's egg. It varies, however, much in size in different individuals. 54 THE UPPER EXTREMITY Dissection. — The branches of the posterior circumflex artery of the humerus and the axillary nerve should now be dissected out on the deep surface of the deltoid muscle. Arteriae Circumflexae Humeri (O.T. Circumflex Arteries). The arteria circumflexa humeri posterior has been already observed to arise within the axilla from the posterior aspect of the axillary artery a short distance distal to the subscapular branch. It at once proceeds backwards, through the quadri- lateral space, and, winding round the surgical neck of the humerus, it is distributed in numerous branches to the deep surface of the deltoid muscle. Several twigs are also given to the shoulder-joint and the integument. It anastomoses with H. Transverse section of the humerus immediately be- low the tuberosities. A. A. Axillary artery. P.C. Posterior circumflex artery. A.C. Anterior circumflex artery. C.-'V. Axillary nerve. a. Articular branch. T.M. Branch to teres minor. C. Cutaneous branches. FIG. 23. — Diagram of the Circumflex Vessels and Axillary Nerve. the acromial branch of the thoraco-acromial artery and the art. circumflexa humeri anterior, and also, by one or more twigs which it sends distally to the long head of the triceps, with thejprofunda branch of the brachial artery. The termination of the arteria circumflexa humeri anterior can now be more satisfactorily studied, and its anastomosis with the art. circumflexa humeri posterior established if the injection has flowed well. By this anastomosis the arterial ring which encircles the proximal part of the humerus is completed. Nervus Axillaris (O.T. Circumflex Nerve). — This nerve accompanies the posterior circumflex artery, and supplies — (a) muscular branches to the deltoid and teres minor ; (b) cutaneous branches to the skin over the distal part of the deltoid ; and (c) an articular twig to the shoulder-joint. The SHOULDER— SCAPULAR REGION 55 following is the manner in which it is distributed. It springs from the posterior cord of the brachial plexus, turns round the lower border of the subscapularis, and proceeds backwards, with the posterior circumflex artery of the M. triceps (cap. long.) Groove for circumflex artery of scapula (O.T. dorsahs scapulae) — M. latissimus dorsi (scapular slip) FIG. 24. — Dorsum of Scapula with the Attachments of the Muscles mapped out. humerus, through the quadrilateral space. Reaching the posterior aspect of the limb, it divides into an anterior and a posterior division. The articular branch takes origin from the trunk of the nerve, and enters the joint below the subscapularis muscle. The posterior division gives off the i— 46 5 6 THE UPPER EXTREMITY branch to the teres minor, and, after furnishing a few twigs to the posterior part of the deltoid, is continued onwards, as the lateral cutaneous nerve of the arm, which has already been dissected in the superficial fascia over the lower part of the deltoid (Fig. 22). The nerve to the teres minor is distinguished by the presence of an oval gangliform swelling upon it. The anterior division proceeds round the humerus with the posterior circumflex artery of the humerus, and ends near the anterior border of the deltoid. It is distributed by many branches to the deep surface of this muscle, whilst a few fine filaments pierce the deltoid and reach the skin. M. Teres Major. — The part which the teres major plays in the formation of the quadrilateral and triangular spaces has already been seen. It arises from the oval surface on the dorsum of the scapula close to the inferior angle of the bone (Fig. 24, p. 55), and also from the septa which the infra- spinous fascia sends in to separate it from the infraspinatus and teres minor muscles. It is inserted into the medial lip of the intertubercular sulcus on the upper part of the humerus (Fig. 33, p. 79), and is supplied by the lower sub- scapular nerve. Insertions of Latissimus Dorsi and Pectoralis Major.— The narrow, band-like tendon of the latissimus dorsi lies in front of the insertion of the teres major. From its inferior margin a small fibrous slip will be observed passing downwards, beyond the lower margin of the teres major, to find attachment to the long head of the triceps (Fig. 22). This is a rudiment of the dorsi-epitrochlearis muscle of the lower animals. The tendons of the teres major and latissimus dorsi should now be separated from each other. They will be found to be more or less adherent, and a small bursa mucosa will be discovered between them. The insertion of the latissimus dorsi into the bottom of the intertubercular sulcus of the humerus may now be satisfactorily studied. The tendon of insertion of the pectoralis major, which is attached to the lateral lip of the intertubercular sulcus, may also be conveniently examined at this stage (p. 13). A separation of the sternal and clavicular portions of the muscle will bring into view the two laminoe which constitute the tendon, and the following points may be noted in connection -with these : — (a) that they are continuous with each other below, or, in other words, that the tendon is simply folded upon itself ; (b) that the posterior lamina extends upwards on the humerus to a higher level than the anterior, and that a fibrous expansion proceeds upwards from its superior border, to seek attachment to the capsule of the shoulder-joint and the lesser tuberosity of the humerus ; (c) that the lower border is connected with the fascia of the upper arm. Articulatio Acromio - Clavicularis (Acromio - clavicular SHOULDER— SCAPULAR REGION 57 Joint). — This is a diarthrodial joint, and the ligaments which bind the bones together are : — Ligaments proper to the f I. Superior } kr> joint . . . \ 2. Inferior / Accessory ligaments— Coraco-clavicular | The superior acromio- clavicular ligament is a broad band, composed of stout fibres, which is placed on the upper aspect of the joint. The inferior acromio-clavicular ligament which closes the joint below is not so strongly developed. In front and behind, these ligaments are connected with each other so as to constitute a capsule. The joint should now be opened, when it will be seen to be lined by a synovial membrane. An imperfect meniscus is also usually present. It is wedge-shaped, and connected by its base to the superior ligament, whilst its free margin is directed downwards between the bones. Lig. Coracoclaviculare (Coraco-clavicular Ligament). — This powerful ligament binds the under surface of the clavicle to the base of the coracoid process. When thoroughly cleaned and defined it will be seen to consist of two parts, which are termed the conoid and the trapezoid ligaments. The ligamentum conoideum placed upon the posterior and medial aspect of the lig. trapezoideum is broad above, where it is attached to the coracoid tubercle of the clavicle (Fig. 5, p. 12), and somewhat narrower below at its attach- ment to the medial part of the root of the coracoid process. The ligamentum trapezoideum is the anterior and lateral part. Above, it is attached along the trapezoid line of the clavicle (Fig. 5, p. 12), whilst .below it is fixed to the upper aspect of the coracoid process. In the recess between these two ligaments a bursa mucosa will usually be found. Arcus Coracoacromialis (Coraco-acromial Arch). — It is necessary to examine this arch at the present stage, as the next step in the dissection will, in a great measure, destroy it. It is the arch which overhangs the shoulder-joint and protects it from above. It is formed by the coracoid process, the acromion, and a ligament — the coraco-acromial — which stretches between them. The ligamentum coracoacromiale is a strong band of a some- what triangular shape. By its base it is attached to the lateral 58 THE UPPER EXTREMITY border of the coracoid process, whilst by its apex it is attached to the extremity of the acromion (Fig. 39, p. 91). The coraco-acromial arch plays a very important part in the mechanism of the shoulder; it might almost be said to form a secondary socket for the humerus. We have already noted the large bursa which intervenes between the acromion and the muscles immediately covering the capsule of the shoulder-joint, to facilitate the movements of the upper end of the humerus on the under surface of the arch. Dissection. — The supraspinatus, infraspinatus, and teres minor muscles which arise from the dorsal surface of the scapulae, and the subscapularis, which takes origin from the costal surface of the scapula, may now be examined. In order to obtain an uninterrupted view of the supraspinatus muscle, the acromion must be divided, with the saw, close to its junction with the spine of the scapulne (Fig. 21, p. 51). Divide also the fascia which covers the teres minor muscle, and reflect it towards the infraspinatus. By this means the septum from the infraspinous fascia, which dips in between the two muscles, will be demonstrated, and their separation rendered easy. Care must be taken not to injure the circumflex artery of the scapula which passes between the teres minor and the bone. M. Supraspinatus. — The supraspinatus muscle arises from the medial two-thirds of the supraspinous fossa, and also to a slight degree from the supraspinous fascia which covers it. From this origin the fibres converge, as they pass laterally, and, proceeding under the acromion, they end in a short, stout tendon, which is inserted into the uppermost of the three impressions on the greater tubercle of the humerus (Fig. 33, p. 79). This tendon is closely adherent to the capsule of the shoulder-joint. The supraspinatus is covered by the trapezius, and in the loose fat which intervenes between this muscle and the supraspinous fascia some twigs of the superficial cervical artery ramify. It is supplied by the suprascapular nerve, and it is an abductor of the upper extremity. M. Teres Minor. — This is the small muscle which lies along the lower border of the infraspinatus. It arises from an elongated flat impression on the dorsal aspect of the axillary border of the scapula, and from the septa of the infraspinous fascia which intervene between it and the two muscles between which it lies, viz. the infraspinatus and teres major. It is inserted into the lowest of the three impressions on the greater tubercle of the humerus, and also, by fleshy fibres, into the body of the bone for about half an inch below this (Fig. 36, p. 84). Towards its insertion it is SHOULDER— SCAPULAR REGION 59 separated from the teres major by the long head of the triceps brachii. The teres minor is supplied by a branch from the axillary nerve. It is an adductor and lateral rotator of the upper extremity. M. Infraspinatus. — This muscle arises from the whole of the infraspinous fossa, with the exception of a small part of it near the neck of the scapula. It also derives fibres from the fascia which covers it. Its tendon of insertion is closely adherent to the capsule of the shoulder-joint, and is attached to the middle impression on the greater tubercle of the humerus (Fig. 36, p. 84). It is supplied by the suprascapular nerve, and is an adductor and lateral rotator of the upper extremity. M. Subscapularis. — The subscapularis muscle arises from the whole of the subscapular fossa, with the exception of a small portion near the neck of the scapula ; it also takes origin from the groove which is present on the costal aspect of the axillary border of the bone (Fig. 33, p. 79). Its origin is strengthened by tendinous intersections, which are attached to the ridges which are present on the costal surface of the scapula. The fleshy fibres thus derived converge upon a stout tendon, which is inserted into the smaller tubercle of the humerus ; a few of the lower fibres, however, gain independent insertion into the body of the humerus below the tubercle. As the muscle proceeds laterally to its insertion, it passes under an arch formed by the coracoid process and the con- joined origin of the short head of the biceps brachii and the coraco-brachialis. By dissecting between the upper border of the muscle and the root of the coracoid process, a bursa of some size will be discovered. This bursa communicates with the cavity of the shoulder-joint through an aperture in the capsule : in other words, its walls are directly continuous with the synovial membrane of the capsule. This can readily be ascertained by making an incision into it. An instrument can then be passed into the joint. The subscapularis is supplied by the upper and lower subscapular nerves. It is an adductor and medial rotator of the upper extremity. Dissection. — The transverse scapular artery and suprascapular nerve must now be followed to their distribution on the dorsum of the scapula. They have already been traced to the superior border of the scapula. Divide the infraspinatus muscle about an inch and a half from its insertion, 60 THE UPPER EXTREMITY taking care not to injure the subjacent vessels. Pull the muscle cautiously backwards, and its nerve of supply with the terminations of the transverse artery of the scapula and the circumflex artery of the scapula will be exposed. Treat the supraspinatus muscle in a similar manner (Fig. 37, p. 86). Arteria Transversa Scapulae (O.T. Suprascapular Artery).— This vessel enters the supraspinous fossa by passing over the ligament which bridges across the incisura scapularis. It divides, under cover of the supraspinatus muscle, into a supra- spinous and an infraspinous branch. The former supplies the supraspinatus muscle, and gives off the chief nutrient artery to the scapula ; the latter proceeds downwards in the great scapular notch, and under cover of the inferior transverse scapular ligament, to reach the deep surface of the infra- spinatus muscle to which it is distributed. At the superior border of the scapula the transverse artery of the scapula gives off a branch (ramus subscapularis] which enters the subscapular fossa under cover of the subscapularis muscle. Nervus Suprascapularis (Suprascapular Nerve). — This nerve accompanies the transverse artery of the scapula, but it enters the supraspinous fossa by passing through the incisura scapulae, under cover of the upper transverse ligament of the scapula. It supplies the supraspinatus, and ends in the infra- spinatus muscle. It usually sends two articular twigs to the posterior aspect of the shoulder-joint, viz. one while in the supraspinous fossa, and the second as it lies in the infra- spinous fossa. Arteria Circumflexa Scapulae (O.T. Dorsalis Scapulas Artery). — This vessel has already been observed to arise from the subscapular branch of the axillary and enter the triangular space. While there it supplies one or two ventral branches, which pass under cover of the subscapular muscle to the subscapular fossa, and a larger infrascapular branch which runs downwards in the interval between the teres major and teres minor to the inferior angle of the scapula (Fig. 21, p. 51). After these branches are given off, the circumflex scapular artery leaves the triangular space by turning round the axillary border of the scapula, under cover of the teres minor. It now enters the infraspinous fossa, where it ramifies and supplies branches to the infraspinatus muscle. Anastomosis around the Scapula. — An important and free anastomosis takes place around the scapula. Three main SHOULDER— SCAPULAR REGION 61 blood-vessels take part in this, viz. — (a) the transverse artery of the scapula; (6) ramus descendens of the transverse cervical artery ; and (c) the subscapular artery. The ramus descendens of the transverse cervical artery (O.T. posterior scapular) runs downwards in relation to the vertebral border of the scapula, and dispenses branches upon both the dorsal and costal aspects of the bone. The subscapular artery runs downwards and medially along the axillary border of the scapula, and at the inferior angle some of its terminal branches anastomose with the terminal twigs of the ramus descendens of the transverse cervical artery. The transverse artery of the scapula is brought into communication with the ramus descendens of the transverse cervical artery at the upper margin, by an anastomosis in the neighbourhood of the medial angle of the bone. But still more distinct anastomoses take place upon the dorsal and costal aspects of the bone. In the supraspinous fossa, branches of the transverse artery of the scapula inosculate with twigs from the ramus descendens of the transverse cervical artery ; whilst in the infraspinous fossa, free communications are established between the circumflex artery of the scapula, the transverse artery of the scapula, and the ramus descendens of the transverse cervical artery. On the ventral aspect of the scapula, the ventral branch of the transverse artery of the scapula, the ventral branches of the circumflex artery of the scapula, and the ventral branches of the ramus descendens of the transverse cervical artery join to form a network. The importance of this free communication between the blood-vessels in relation to the scapula will be manifest when it is remembered that two of the main arteries, viz. the ramus descendens of the transverse cervical artery and the transverse artery of the scapula spring indirectly from the first part of the subclavian; whilst the third, viz. the subscapular, arises from the third part of the axillary. When, therefore, a ligature is applied to any part of the great arterial trunk of the upper limb, between the first stage of the subclavian and the third part of the axillary, this anastomosis affords ample means of re-establishing the circulation. Dissection. — Detach the subscapularis from the scapula and lift it laterally to its insertion. This will afford a better view of its relation to the capsule of the shoulder-joint, and also of the subscapular bursa. In a well-injected subject the ventral anastomosis can likewise be made out. Ligamentum Transversum Scapulae Superius (O.T. Supra- scapular Ligament) and Lig. Trans versum Scapulae Inferius (O.T. Spinoglenoid Ligament). — These are two ligamentous 62 THE UPPER EXTREMITY bands, which are placed in relation to the transverse artery of the scapula and the suprascapular nerve. The upper transverse ligament of the scapula bridges across the incisura scapulae and converts it into a foramen. It lies between the transverse artery of the scapula and the suprascapular nerve : the former being placed above it, and the latter below it. Not infrequently it is ossified. The inferior transverse ligament of the scapula is a weaker band; it bridges across the transverse artery of the scapula and the suprascapular nerve as they pass through the great scapular notch. On the one hand, it is attached to the lateral border of the spine of the scapula, and on the other, to the back part of the neck of the scapula. FRONT OF THE ARM. In this dissection the following parts have to be studied :— 1. Cutaneous vessels and nerves. 2. Brachial aponeurosis. 3. Brachial artery and its branches. 4. Median, ulnar, radial, and musculo-cutaneous nerves and branches of the last two. 5. Biceps, coraco-brachialis, and brachialis muscles. In conjunction with this dissection, it is convenient to study the triangular space in front of the elbow, and also to trace the cutaneous nerves to their ultimate distribution in the skin of the forearm. Surface Anatomy. — In a muscular limb the prominence formed by the biceps muscle along the front of the upper arm is very apparent. Every one is familiar with the rounded swelling which it produces when powerfully contracted in the living subject. On either side of the biceps there is a feebly marked furrow, and ascending in each of these there is a large superficial vein. In the lateral furrow is the cephalic vein ; in the lower part of the medial furrow the basilic vein. In the upper part of the medial bicipital sulcus is an elongated bulging produced by the subjacent coraco-brachialis muscle. This is useful as a guide to the lower part of the axillary and the upper part of the brachialis arteries, which lie FRONT OF THE ARM immediately behind and to the medial -side of it. The humerus is thickly clothed by muscles ; but towards its lower part the two epicondyloid ridges, leading down to the epicondylar eminences, may be felt. The lateral ridge is the more salient of the two, and therefore the more evident to touch. The bony points around the elbow require to be studied FIG. 26. — Relation of the bones of the Elbow to the surface. Dorsal view ; FIG. 25. —Relation of bones elbow bent. of Elbow to the surface. Dorsal view ; elbow fully extended. with especial care. It is by a proper knowledge of the normal relative positions of these that the surgeon is able to distinguish between the different forms of fracture and dis- location which so frequently occur in this region. First note the medial epicondyle of the humerus. This constitutes a prominence, appreciable to the eye ; grasp it between the finger and thumb, and note that it inclines dorsally as well as medially. In a well-developed, fully extended arm, the lateral epicondyle does not form a projection on the surface, but can be felt at the bottom of a slight depression 64 THE UPPER EXTREMITY on the dorsal aspect of the limb. It becomes apparent to the eye as a prominence when the elbow is semi-flexed. The olecranon produces a marked projection on the dorsum of the elbow between the two epicondyles. It is placed slightly nearer to the medial than to the lateral epicondyle. The loose skin which covers the olecranon moves freely over its subcutaneous surface, owing to the interposition of a bursa mucosa. The different positions which are assumed by the olecranon, in relation to the epicondyles of the humerus in the movements of the forearm at the elbow-joint, must be carefully examined. This can best be done by placing the thumb on one epicondyle, the middle finger on the other, and the forefinger on the olecranon. The limb should then be alternately flexed and extended, so as to make clear the extent of the excursion performed by the olecranon. In full extension at the elbow-joint the three prominences lie in the same horizontal line ; when the forearm is bent at a right angle the three bony points are placed at the angles of an equilateral triangle, the apex of which points distally. When the forearm is extended a marked depression on the dorsal aspect of the elbow indicates the position of the articula- tion between the radius and the humerus. Immediately distal to this the head of the radius lies close to the surface, and can readily be felt, especially when it is made to roll under the finger by inducing alternately the movements of pronation and supination. The head of the radius is placed about an inch distal to the lateral epicondyle. As the skin of the forearm must be reflected in the pur- suit of the cutaneous nerves, it is well, at this stage, to study also the external anatomy of this segment of the limb. In its proximal half the radius is deeply imbedded in muscles, but in its distal half it can be felt, and its styloid process on the lateral side of the carpus can be readily distinguished. On the dorsal aspect of the distal end of the radius immediately above the radiocarpal joint, and nearer the lateral than the medial border of the limb, a prominent bony tubercle may be felt. This is the high ridge which forms the lateral wall of the sharply cut groove on the dorsal aspect of the radius in which the tendon of the extensor pollicis longus muscle plays. The sinuous dorsal border of the ulna is subcutaneous, and may be followed by the finger throughout its entire length ; as the elbow is approached it leads directly on FRONT OF THE ARM 65 to the subcutaneous surface on the back of the olecranon. In cases of suspected fracture, therefore, this border affords valuable information. The styloid process of the ulna may be detected, immediately above the wrist, and it should be observed that this does not extend so far distally as the corresponding process of the radius. The rounded distal end of the ulna makes a marked projection on the medial and dorsal aspect of the limb immediately proximal to the wrist- joint, and lying in the groove between it and the styloid process the tendon of the extensor carpi ulnaris may be felt. Reflection of Skin. — The skin should be removed from the limb as far down as the radio-carpal joint. It is necessary to do this in order that a connected view may be obtained of the cutaneous nerves and the superficial veins. But at the same time the skin should not be cast aside, as it forms a most efficient protective wrapping for the part even after it has been detached. Make one long incision along the middle of the anterior aspect of the arm and the volar surface of the forearm down to the radiocarpal articulation. A second incision carried transversely round the distal end of the forearm, immediately above the radio-carpal joint, will enable the dissector to reflect the skin in two large flaps, medially and laterally. In the fatty superficial fascia which is then exposed, the superficial structures may be traced. It is well to begin with the nerves, as these are not so apparent and, therefore, more liable to injury than the veins. But the dissection of the veins should be carried on concurrently with that of the nerves. Nervi Cutanei (Cutaneous Nerves). — These are very numerous, and are derived from several sources. In addition to the two medial cutaneous nerves, which spring from the brachial plexus, there are the terminal cutaneous part of the musculo- cutaneous nerve, three branches derived from the radial nerve and one — the intercostobrachial nerve — form the second thoracic nerve. These seven nerves may be classified into a medial and a lateral group as follows :— 1 Distributed mainly i. N. cutaneus antibrachu dorsahs upper branch, I the . . iu as upper ranc, the 2. N. cutaneus antibrachu dorsahs lower branch, r *;_# nf fi AT ,., , .. , ,. part oi me arm 3. N. cutaneus antibrachu laterahs, j Jnd forearm< I. N. intercostobrachialis, "\ 2. N. cutaneus brachii posterior, I Distributed mainly upon the medial 3. N. cutaneus brachii medialis, j part of the arm and forearm. 4. N. cutaneus antibrachii medialis, J The two dorsal cutaneous nerves of the forearm pierce the deep fascia about the middle of the lateral surface of the arm immediately distal to the insertion of the deltoid, and VOL. i — 5 66 THE UPPER EXTREMITY in close relation to the lateral intermuscular septum. The Posterior supra-clavicular nerves Lateral brachial cutaneous nerve - Posterior brachial cutaneous nerve Intercosto-brachial nerve Branch of medial cutaneous nerve of forearm Medial brachial cutaneous nerve Dorsal cutaneous nerve of forearm, \ upper and lower branches / Medial cutaneous nerve of forearm Cephalic vein Basilic vein Median basilic vein Median cephalic vein — Lateral cutaneous nerve of forearm — Profunda vein Cephalic vein Basilic veins-! Median vein Palmar cutaneous branch of median nerve Palmar cutaneous branch of ulnar nerve Palmar cutaneous branch of superficial branch of radial nerve FIG. 27. — Cutaneous Nerves on the Front of the Upper Extremity. smaller upper branch appears a short distance above the other. It follows the cephalic vein, and can be traced FRONT OF THE ARM 67 distally as far as the elbow. Its filaments are distributed to the skin over the lateral and anterior part of the distal half of the arm. The larger lower branch can be followed as far as the wrist, and not infrequently its terminal filaments even reach the dorsum of the hand. It supplies the skin on the dorsal aspect of the forearm. It should be borne in mind that the skin on the lateral aspect of the limb, above these nerves and over the deltoid, is supplied by the cutaneous branches of the axillary nerve and the posterior supraclavicular nerves of the cervical plexus (P- 48). The lateral cutaneous nerve of the forearm is the terminal part of the musculo- cutaneous nerve. It will be found in front of the elbow-joint where it pierces the deep fascia on the lateral side of the tendon of the biceps brachii. It is a large nerve, and proceeds distally behind the median cephalic vein. The skin, both upon the volar and dorsal aspects of the lateral side of the forearm, is supplied by this nerve, and it is distributed by two main branches. The larger volar branch can be traced as far as the skin over the ball of the thumb. A few of its terminal twigs pierce the fascia above the wrist, and join the radial artery, by which they are conducted to the dorsal aspect of the carpus. The dorsal branch may be followed on the dorsal aspect of the limb as far as the wrist. The intercosto-brachial nerve can usually be traced half-way down the arm ; but the area of skin which it supplies is somewhat variable. The posterior cutaneous nerve of the arm is a branch of the radial (musculo-spiral) nerve. It proceeds downwards and backwards on a deeper plane, and crosses posterior to the intercosto-brachial nerve. Its filaments extend upon the back of the arm as low as the elbow-joint. The medial brachial cutaneous nerve will be found piercing the deep fascia, to become superficial, half-way down the medial side of the arm. Its twigs may be followed, in the superficial fascia, as' far as the olecranon. On the medial side of the arm, on its dorsal aspect, three nerves therefore have been traced. From the medial to the lateral side these are : the medial brachial cutaneous nerve, the intercosto-brachial nerve, and the posterior cutaneous brachial branch of the radial nerve (Fig. 28). The medial cutaneous nerve of the forearm (internal 68 THE UPPER EXTREMITY cutaneous nerve) is chiefly destined for the supply of the Posterior supraclavicular nerves Lateral cutaneous nerve of arm / Posterior cutaneous nerve of \arrn / Posterior cutaneous nerve of \ forearm, upper branch Intercosto-brachial nerve - Medial cutaneous nerve of arm Posterior cutaneous nerve of fore- arm, lower branch Medial cutaneous nerve of forearm, ulnar branch Lateral cutaneous nerve of forearm, dorsal branch _Superficial division of radial (O.T. nmsculo- spiral = radial nerve of O.T.) Dorsal branch of ulnar nerve FIG. 28. — Cutaneous Nerves on the Dorsal Aspect of the Upper Extremity. skin of the forearm. It appears through the deep fascia half-way down the medial side of the arm close to the FRONT OF THE ARM 69 basilic vein, and a short distance in front of the medial cutaneous nerve of the arm. It at once divides into a volar and an ulnar branch. The volar branch runs down- wards behind (but sometimes in front of) the median basilic vein, and it is distributed to the skin over the medial and volar aspect of the forearm. The ulnar branch, inclining medially, proceeds distally in front of the medial epicon- dyle of the humerus, to reach the skin on the medial and dorsal aspect of the forearm. A small twig is frequently given by the medial cutaneous nerve of the forearm to the skin over the biceps muscle. This pierces the deep fascia close to the axilla. Venae Superficiales (Superficial Veins). — The superficial veins of the anterior aspect of the arm and the volar aspect of the forearm may now be cleaned ; but in all proba- bility they are already for the most part exposed. At least three veins are usually seen ascending along the volar aspect of the forearm, the basilic vein along the medial border, the cephalic vein along the lateral border, and, midway between the two former, the median vein of the forearm. When the median vein reaches the depression in front of the elbow it is joined by a short wide vein which pierces the deep fascia of the forearm and establishes an anastomosis between the deep and the superficial veins of the forearm. This connecting trunk is called the profunda vein. After receiving this tributary the median vein of the forearm divides into two branches which diverge from each other like the limbs of the letter V. The lateral of the two branches is the median cephalic vein, the medial branch is the median basilic vein. The median cephalic vein passes obliquely, proximally and laterally, across the front of the lateral cutaneous nerve of the forearm, and joins the cephalic vein. After it has received the median cephalic vein, the cephalic vein ascends along the lateral bicipital sulcus, continues proxi- mally in the groove between the deltoid and the pectoralis major, crosses the deltopectoral triangle, dips beneath the clavicular part of the pectoralis major crossing in front of the pectoralis minor, pierces the costo-coracoid membrane and terminates in the axillary vein. The median basilic vein is a short wide vessel which passes proximally and medially towards the medial epicondyle. It is larger than the median cephalic vein and has a less oblique yo THE UPPER EXTREMITY course. As it approaches the medial epicondyle of the humerus it joins the basilic vein. The median basilic vein is the vessel commonly selected when the surgeon has recourse to venesection. Therefore the relations of the vein are of practical importance. The dissector should note the following points regarding it : — (i) that it crosses a thickened band of deep fascia known as the lacertus fibrosus of the biceps brachii ; (2) that the lacertus fibrosus separates it from the brachial artery which the vein also crosses; (3) that the volar branch of the medial cutaneous nerve of the forearm usually passes behind it, although in many cases it crosses in front of the vein. The basilic vein having received the median basilic vein runs proximally, on the medial surface of the arm, in the medial bicipital sulcus ; about half-way up the arm it pierces the deep fascia, close to the spot at which the median cutaneous nerve of the forearm emerges, and at the lower border of the posterior wall of the axilla it becomes the axillary vein. The arrangement of the veins of the forearm is extremely variable. In many cases the median vein is absent, and the cephalic and basilic are united, in the anti- cubital region, by a large, oblique, anastomosing channel which lies in the position of the median basilic vein and appears to be the main continuation of the cephalic trunk, the proximal part of the latter vessel being much reduced in size. Lymphoglandulae (Lymph Glands). — If the superficial fascia be searched upon the medial side of the limb, and immediately above the elbow, one or two minute lymph glands will be found in relation to the basilic vein. These are the superficial cubital glands, and they are of interest to dissectors as they are the first to enlarge and become painful in cases of dissection-wound. Fascia Brachii (Brachial Fascia). — The deep fascia should now be cleaned by the removal of the fatty superficial layer. It forms a continuous envelope around the arm, but at no point does it show a great density or strength. Above, it is continuous with the axillary fascia and the fascia covering the pectoralis major and the deltoid. The tendons of these two muscles are closely connected with it — a certain proportion of their tendinous fibres running directly into it. Below, it is firmly fixed to the bony prominences around the elbow, and in front it receives an accession of fibres from the tendon FRONT OF THE ARM 71 of the biceps brachii. The latter fibres constitute the lacertus fibrosus, and form a very distinct band (O.T. semilunar or bicipital fascia) which, continuous with the fascia above and below, bridges across the brachial artery, and is lost upon the pronator teres muscle on the medial side of the forearm. The fascia brachii may be reflected by making an incision through it along the medial line of the front of the arm. In throwing the medial portion medially, the dissector must leave the lacertus fibrosus in position. This may be done by separating it artificially from the general aponeurosis by an incision above and below it. Medial inter- muscular septum Lateral inter- muscular septum FIG. 29. — Diagram (after Turner) to show how the Arm is divided by the intermuscular septa and bone into an anterior and posterior compartment. These compartments are represented in transverse section. As the foregoing dissection is proceeded with, it becomes evident that septa or partitions pass in between the muscles from the deep surface of the investing fascia brachii. Two of these possess a superior strength, and obtain direct attach- ment to the humerus. They are the lateral and medial intermuscular septa. The connections of these cannot be fully studied at present, but it is important that the student should understand their relations at this stage. In the course of the dissection of the arm they will gradually be displayed. The septum intermusculare mediale is the stronger and more distinct of the two. It is attached to the medial epi- condylar ridge, and may be followed proximally as high as the insertion of the coraco-brachialis muscle. The septum intermusculare laterale is fixed to the lateral epicondylar 72 THE UPPER EXTREMITY ridge, and extends up the arm as high as the insertion of the deltoid. The dissector should note that these septa divide the arm into an anterior and a posterior osteo-fascial compartment. Structures in the Anterior Compartment. — The anterior osteo-fascial compartment of the arm has been opened into by the reflection of the front part of the fascia brachii. The three muscles which specially belong to this region are the biceps brachii, brachialis, and the coraco-brachialis. The A. brachialis Sept. inter- _»g muse. med. "I N. ulnaris -, V. cephalica N. musculocutaneus L1-- A. profunda brachii i| - N. radialis .(musculo j spiral) sJCT" M. brachioradialis y*"1 Sept. intermus. lat. .' FIG. 30. — Transverse section through the Distal Third of the Right Arm. biceps brachii is the most superficial muscle : under cover of it, and closely applied to the anterior aspect of the humerus, is the brachialis ; whilst the coraco-brachialis is the slender muscular belly which lies along the medial side of the biceps in its upper part. But, in addition, two muscles of the fore- arm will be observed extending upwards into this compartment of the arm, to seek origin from the lateral epicondylar ridge of the humerus : they are the brachioradialis and the extensor carpi radialis longus. They are closely applied to the lateral side of the brachialis. The brachial artery, with its venae comites, extends through the region in relation to the medial margin of the biceps brachii, and all the terminal branches of the 1>J7. T. W. FRAHM NO. FRONT OF THE ARM 73 cords of the brachial plexus, with the exception of the axillary (circumflex), will be found for some part of their course in this region. The radial nerve (musculo-spiral), it is true, almost at once proceeds to the back of the limb, but it again comes to the front, and may be found in the lower part of the lateral side of the arm, by separating the origins of the brachioradialis and extensor carpi radialis longus from the brachialis, and dissecting deeply in the interval between them. Dissection. — In carrying out this somewhat extensive dissection, the main object of the dissector should be to keep the brachial artery as un- disturbed as possible until he has satisfied himself as to its relations. He is therefore, in the first instance, advised to clean only those parts of the muscles which are in immediate relationship to the vessel and its branches. The divided brachial nerves, with the axillary artery and vein, should be arranged in proper order, and then tied to a small piece of wood about i^ inches long (e.g. a piece of a penholder), held transversely. By means of a loop of string this can then be fastened to the coracoid process. By this device the dissection of the arm will be greatly facilitated. The dissection of the entire length of the brachial artery should be carried out at one and the same time, and its termination in the radial and ulnar arteries should be defined. Arberia Brachialis (Brachial Artery) is the direct continua- tion of the axillary artery ; it begins, therefore, at the distal border of the teres major, and it passes distally and slightly laterally to the cubital fossa where, at the level of the neck of the radius, it divides into its two terminal branches — the radial and the ulnar arteries. In the proximal part of the arm it lies to the medial side of the humerus, but as it approaches the elbow it passes to the front of the humerus. This change of position must be borne in mind when pressure is applied to the vessel with the view of controlling the flow of blood through it. In the upper part of the arm the pressure must be directed laterally and backwards, and in the lower part directly backwards. Relations. — The brachial artery is superficial in the whole of its length, therefore, to expose it, it is only necessary to reflect the skin and the fascia, but it is overlapped, from the lateral side, by the medial margins of the coraco-brachialis and biceps brachii (see Figs. 30, 31). At the bend of the elbow it is crossed superficially by the lacertus fibrosus which intervenes between it and the median basilic vein. The basilic vein lies to the medial side of the artery and on a somewhat posterior plane. In the distal part of the arm it is separated from the artery by the fascia brachii ; but 74 THE UPPER EXTREMITY in the proximal part, after the vein has pierced the fascia, it comes into closer relationship with the artery. The two venae comites are closely applied to the sides of the artery, and the numerous connecting branches which pass between them, both in front of and behind the artery, make the relationship still more intimate. Behind the brachial artery there are four muscles. From above downwards they are (i) the long head of the triceps which is separated from the artery by the radial nerve and the N. musculo- cutaneus ' hept. inter- 5j-- muse. lat. | Hrs. of A. prof. [-- brachii I N. radialis • ~ (musculo-spiral) •• Dorsal cutaneous nerve of arm (O.T. , internal cutan. of musculo-spiral) . FIG. 31. — Transverse section through Middle of Upper Ann. profunda artery. (2) The medial head of the triceps. (3) The insertion of the coraco-brachialis. (4) In the remainder of its course the brachialis forms the posterior relation. With the exception of the musculo-cutaneous nerve all the terminal branches of the brachial plexus lie in relation to the brachial artery. The median nerve lies laterally and somewhat anteriorly in the proximal half of the arm ; it crosses anterior to the artery at the level of the insertion of the coraco-brachialis, and in the distal half of the arm and the cubital fossa it is to the medial side of the artery. The ulnar nerve and the medial cutaneous nerve of the forearm lie close to the medial side of the artery as far as the FRONT OF THE ARM 75 insertion of the coraco-brachialis, then they leave it. The ulnar nerve inclines backwards, pierces the medial inter- muscular septum and, passing behind the medial epicondyle, enters the forearm. The median cutaneous nerve of the forearm inclines forwards and medially, pierces the fascia brachii and becomes superficial. The radial nerve is behind the upper part of the artery, but it soon leaves it by passing distally and laterally into the sulcus or the radial nerve between the medial and the lateral heads of the triceps. Branches of the Brachial Artery. — A considerable number of branches spring from the brachial artery. Those which arise from its lateral aspect are irregular in number, origin, and size. They are termed the lateral branches, and are distributed to the muscles and integument on the front of the arm. The series of medial branches which proceed from the medial and posterior aspect of the parent trunk are named as follows as we meet them from above downwards : — 1. A. profunda brachii. 3. A. nutricia humeri. 2. A. collateralis ulnaris superior. | 4. A. collateralis ulnaris inferior. The arteria profunda brachii (O.T. superior profunda) is the largest of the branches which spring from the brachial trunk. It takes origin about an inch or so distal to the lower margin of the teres major, and associates itself with the radial (musculo-spiral) nerve, which it accompanies to the back of the arm. Consequently, only a short part of the vessel is seen in the present dissection. It soon disappears from view between the long and medial heads of the triceps. The arteria collateralis ulnaris superior (O.T. inferior pro- funda) is a long slender artery, which can be recognised from the fact that it follows closely the course which is pursued by the ulnar nerve. Its origin is somewhat uncertain. As a general rule, it issues from the brachial artery opposite the insertion of the coraco-brachialis, but very frequently it will be seen to arise in common with the profunda brachii. It pierces the medial intermuscular septum, with the ulnar nerve, and descends behind the aponeurotic partition to the interval between the olecranon and the medial epicondyle of the humerus. The arteria nutricia humeri may arise directly from the brachial trunk, or take origin from the superior ulnar 76 THE UPPER EXTREMITY collateral artery. It should be sought for at the distal border of the insertion of the coraco-brachialis, and the dissector should not be satisfied until he has traced it into the medullary foramen of the bone. When the nutrient artery Radial nerve (O.T. musculo- spiral) Anterior branch of profunda— -£j artery Lateral inter- f :*"" muscular septum "t Lower collateral ulnar artery (O.T. an:i- stomotic) V Radial nerve (O.T. musculo-spiral) Profunda artery (O.T. superior profunda). - , Ulnar nerve Upper collateral 'ulnar artery (O.T. inferior profunda) Ulnar nerve Upper collateral ulnar artery" Nerve to medial head of triceps (O.T." ulnar collateral) /I Medial intermuscular Ljf septum Uf Lower collateral ulnar artery (O.T. -JU anastomotic) sj Triceps Gat, head) Nerve to lateral 'head of triceps ^ Nerve to long head of triceps Posterior "brachial cutane- ous nerve (O.T. int. cutan. of musculo-spiral) Lateral anti- brachial cutaneous !; nerves (O.T. !ext. cutan. of ••' musculo- spiral) i Posterior Jt-- branch of pro- \ funda artery Lateral inter- »i- muscular septum Nerve to ancona;us FIG. 32. — Diagram to show relation of Radial Nerve (O.T. Musculo-spiral) to the Humerus and of Vessels and Nerves to the Intermuscular Septa. is not seen in its usual position it will probably be found in the dissection of the back of the arm, taking origin from the profunda artery. The arteria collateralis ulnaris inferior (O.T. anastomotica) arises about two inches proximal to the bend of the elbow, and runs medially upon the brachialis. It soon divides into a small anterior and a larger posterior branch. The anterior branch is FRONT OF THE ARM 77 carried distally in front of the medial epicondyle of the humerus, in the interval between the brachialis and the pronator teres. It anastomoses in this situation with the anterior ulnar recurrent artery. The posterior branch pierces the medial intermuscular septum and will be seen later on in the posterior compartment of the arm. The N. Cutaneus Brachii Medialis and Nervus Cutaneus Antibrachii Medialis (O.T. Lesser Internal Cutaneous and Internal Cutaneous Nerves). — Very little more requires to be said about these nerves. Their origin within the axilla has already been noted, and they have been traced to their distri- bution from the points where they pierce the investing fascia brachii. It only remains for the dissector to examine them in that part of their course in which they lie under cover of the fascia brachii. It will be observed that they both lie along the medial side of the brachial artery. The medial cutaneous nerve of the arm gives off, as a rule, no branches in this situation, except one or more twigs of communica- tion to the intercosto-brachial nerve. The medial cutaneous nerve of the forearm gives off the branch which pierces the fascia to supply the skin in front of the biceps brachii. Nervus Medianus et Nervus Ulnaris (Median and Ulnar Nerves). — These large nerve trunks do not furnish any branches in the arm. The median nerve arises in the axilla by two heads from the lateral and medial cords of the brachial plexus. It proceeds distally upon the lateral and superficial aspect of the axillary and brachial arteries, until it approaches the level of the insertion of the coraco- brachialis. Here it lies in front of the brachial artery. Finally, it reaches the medial side of the vessel, and main- tains this position for the rest of its course in the arm. The ulnar nerve is the largest branch of the medial cord of the brachial plexus. It descends upon the medial side of the axillary and brachial arteries, and at the insertion of the coraco-brachialis it encounters the superior ulnar collateral artery. Accompanied by this vessel, it leaves the brachial artery, passes backwards through the medial intermuscular septum, and it is continued downwards, upon the posterior aspect of this aponeurotic partition, to the interval between the olecranon and medial epicondyle of the humerus. Dissection. — The muscles should now be thoroughly cleaned, and the musculo-cutaneous nerve and its branches dissected out. 78 THE UPPER EXTREMITY Nervus Musculocutaneus.— The musculo-cutaneous nerve arises from the lateral cord of the brachial plexus, at the lower border of the pectoralis minor. Inclining laterally, it perforates the coraco-brachialis, and appears between the biceps brachii and the brachialis. It proceeds obliquely distally between these muscles until it reaches the bend of the elbow, where it comes to the surface at the lateral border of the tendon of the biceps brachii. From this point onwards it has already been traced as the lateral cutaneous nerve of the forearm (p. 67). In the upper arm the musculo-cutaneous supplies branches to the three muscles in this region. The branch to the coraco-brachialis is given off before the parent trunk enters the substance of the muscle ; the branches to the biceps brachii and brachialis issue from it as it lies between them. M. Coracobrachialis. — This is an elongated muscle, which takes origin from the tip of the coracoid process in con- junction with the short head of the biceps brachii. It pro- ceeds distally, along the medial margin of the biceps brachii, and obtains insertion into a linear ridge situated upon the medial aspect of the body of the humerus about its middle. M. Biceps Brachii (O.T. Biceps).— The biceps brachii muscle arises from the scapula by two distinct heads of origin. The short or medial head springs from the tip of the coracoid process in conjunction with the coraco-brachialis (Fig. 15, p. 34). The long or lateral head is a rounded tendon, which occupies the intertubercular sulcus of the humerus. Its origin cannot be studied at this stage of the dissection because it is placed within the capsule of the shoulder-joint. Suffice it for the present to say, that it arises from an im- pression on the scapula immediately above the glenoid cavity. Both heads swell out into elongated fleshy bellies, which, at first, are closely applied to each other, and afterwards united in the lower third of the arm. Towards the bend of the elbow the fleshy fibres converge upon a stout, short tendon, which is inserted into the dorsal part of the tuberosity of the radius. This insertion will be more fully examined at a later period, but it may be noticed in the meantime that the tendon is twisted so as to present its margins to the front and dorsal aspect of the limb, and further, that a bursa mucosa is interposed between it and the volar smooth part of the radial tuberosity. FRONT OF THE ARM 79 The dissector has al- ready taken notice of the lace rt us fibrosus, and has separated it artificially from the fascia brachii above, and from the fascia anti- brachii below. Observe now that it springs from the anterior margin of the tendon of the biceps brachii, and that it likewise receives some muscular fibres from the short head of the muscle. M. Brachialis (O.T. Brachialis Anticus). — The brachialis arises from the entire width of the anterior surface of the distal half of the body of the humerus, from the medial inter- muscular septum, and from a small part of the lateral intermuscular septum above the brachioradialis. The origin from the bone is prolonged upwards in two slips which partially embrace the insertion of the deltoid. The fibres converge to be inserted into the base of the coro- noid process of the ulna by a short, thick tendon. The muscle lies partly under cover of the biceps brachii, but projects be- yond it on either side. It is overlapped on its medial side by the pronator teres, and on the lateral side by 1 the brachioradialis and ex- Supraspinatus Subscapularis '— Latissimus dorsi Pectoralis major — Teres major r. Deltoid L Coraco-brachialis -- Brachioradialis Extensor carpi radialis longus Extensors Pronator radii teres and flexors . J. 33. — Anterior aspect of Humerus with Muscular Attachments mapped out. 8o THE UPPER EXTREMITY tensor carpi radialis longus. Its deep surface is closely connected to the anterior part of the capsule of the elbow- joint, its chief nerve of supply, from the musculo-cutaneous, Lateral end of clavicle ^^-Margin of acromion process Pectoralis major ,, Cephalic vein L — Deltoid Cutaneous branches of Axillary nevve piercing deltoid Lateral hrachial cutaneous branch of axillary (O. T. circumflex) nerve Biceps brachii Lateral head of triceps Brachialis Upper branch of dorsal cutaneous nerve of forearm Cephalic vein Lower branch of dorsal cutaneous nerve of forearm Brachioradialis Tendon of triceps Olecranon Extensor carpi radialis longus FIG. 34.— The Deltoid Muscle and the lateral aspect of the Arm. has already been secured, but it also receives one or two small twigs from the radial (tnusculo-spirat) nerve which are given off under cover of the brachioradialis. Dissection. — Separate the brachioradialis from the brachialis muscle, FRONT OF THE ARM 81 and dissect out the radial nerve, with the anterior terminal branch of the profunda brachii artery, which lie deeply in the interval between them. Here also the anastomosis between the profunda brachii artery and the radial recurrent arteries may be made out, in a well-injected subject ; and the twigs which are given by the radial nerve to the brachialis, the brachioradialis, and the extensor carpi radialis longus, should be looked for. Fossa Cubitalis (O.T. Antecubital Fossa). — This is a slight hollow in front of the elbow-joint. It corresponds to the fossa poplitea of the lower extremity, and within its area the brachial artery divides into its two terminal branches. In the first instance, consider the structures which cover it. Some of these have already been removed, they are the skin, superficial fascia, and deep fascia. Within the superficial fascia are the median basilic and median cephalic veins, the volar branch of the medial cutaneous nerve of the forearm and the lateral cutaneous nerve of the forearm. These structures constitute the coverings of the fossa. The fossa is triangular. Its base is directed proximally, and is usually regarded as being formed by a line drawn between the two epicondyles of the humerus. The medial boundary is the pronator teres muscle, and the lateral boundary the brachioradialis. The meeting of the two muscles distally constitutes the apex of the fossa. The boundaries must first be cleaned, then the contents of the fossa may be dissected. Within the fossa is the termination of the brachial artery and the proximal parts of the radial and ulnar arteries, into which it divides. To the lateral side of the main vessel is placed the tendon of the biceps brachii, and to its medial side the median nerve. A quantity of loose fat is also present. The ulnar artery leaves the space by passing under cover of the pronator teres ; the radial artery is continued distally beyond the apex of the fossa, overlapped by the brachioradialis. The median nerve disappears between the two heads of the pronator teres, and the tendon of the biceps brachii inclines posteriorly, between the two bones of the forearm, to reach its insertion into the radial tuberosity. When the fatty tissue has been thoroughly removed the floor of the space will be revealed. This is formed by the brachialis and the supinator muscles. In this situation the brachialis is closely applied to the anterior aspect of the elbow-joint, whilst the supinator is wrapped round the upper part of the radius. VOL. i — 6 82 THE UPPER EXTREMITY Now divide the lacertus fibrosus, and separate the bounding muscles widely from each other. Other structures come into view, but they cannot, strictly speaking, be regarded as lying within the space proper. They are — (i) the radial nerve, N. cutan. antib. med. Fascia brachii V. basilica A. brachialis N. cut. antib. med. N. medianus *~Vfl A. recurr. ulnaris ant. ' N. to m. pronat. teres N. to m. flex. carp. rad. A. ulnaris Lacertus fibrosus M. pronat. teres, deep head M. flex. carp. rad. M. palmaris long. - N. cut. antib. med. V. basilica - N. cutan. antibrachii lat. ram. volaris V. cephalica M. brachialis N. cutan. antib. lat. ram. dorsalis .N, radialis (O.T. musculo-spiral) Lacertus fibrosus N. radialis ram. superf. (O.T. radial) N. radialis ram. prof. Tendon of m. biceps brachii A. recurr. radialis M. supinator M. brachioradialis A. radialis N. cutan. antib. lat. ram. volaris V. mediana FIG. 35. — Dissection of the Left Antecubital Fossa. (musculo-spiral), the anterior branch of the profunda brachii artery, and the recurrent branches of the radial artery, lying deeply in the interval between the brachioradialis and the brachialis; (2) the anterior branch of the inferior ulnar collateral artery and the anterior recurrent branch of the ulnar artery, placed under cover of the pronator teres. DORSUM OF THE ARM 83 DORSUM OF THE ARM. In this region the following are the structures which require to be studied : — 1. The triceps muscle. 2. The a. profunda brachii, and the n. radialis (musculo-spiral). 3. The a. collateral ulnaris superior, and the n. ulnaris. 4. The posterior branch of the a. collateralis ulnaris inferior. 5. The m. subancomeus. Dissection. — The skin has already been removed from the dorsum of the arm. The deep fascia should now be raised from the surface of the m. triceps, and its three heads cleaned and isolated from each other. To place the muscle on the stretch, the inferior angle of the scapula should be raised as high as possible, and the forearm flexed at the elbow-joint. The radial nerve, together with the a. profunda brachii, must at the same time receive the attention of the dissector. They should be followed back- wards between the heads of the triceps, and all their branches should be carefully preserved. M. Triceps Brachii (O.T. Triceps). — This muscle occupies the entire posterior osteo-fascial compartment of the upper arm. It arises by a long or middle head from the scapula, and by two shorter heads, lateral and medial, from the humerus. The fleshy fibres of these three heads join a common tendon, which is inserted into the top of the olecranon of the ulna. The superficial part of the muscle is, for the most part, formed by the long head and the lateral head of the muscle. The medial head is deeply placed ; only a very small portion of it appears superficially, in the lower part of the arm, on each side of the common tendon of insertion. The caput longum of the triceps arises, by a flattened tendon, from the rough triangular impression on the upper part of the axillary border and the lower aspect of the neck of the scapula (Fig. 15, p. 34). This tendon takes origin in the interval between the teres minor and subscapularis muscles. The two humeral heads take origin from the posterior aspect of the humerus ; and if it be borne in mind that no fibres arise from the sulcus for the radial nerve and that the groove in- tervenes between the origins of the two heads, their rela- tions will be easily understood. The dissector should provide himself with a humerus, and, having first identified the sulcus for the radial nerve, proceed to map out the areas of attach- 84 THE UPPER EXTREMITY Teres minor Infraspinatus Triceps (outer head) ment of the humeral heads are Brachialis Musculo-spiral exhibited in the dissected part. The caput laterak of the triceps arises from the lat- eral and posterior aspect of the body of the humerus, proximal to the sulcus for the radial nerve. It takes origin, by short tendinous fibres, along a line which descends verti- cally from the insertion of the teres minor above to the upper border of the sulcus for the radial nerve. But it also derives fibres from a strong aponeurotic bridge or arch, which is thrown over the groove, so as to give protection to the a. profunda brachii and the radial nerve. The strength and position of this arch can be tested by thrusting the handle of the knife distally and laterally in the sulcus for the radial nerve, and along the course of the nerve and artery under the lateral head of the triceps. By its distal end the arch is connected with the lateral intermuscular septum. The caput mediate of the triceps is placed distal to the sulcus for the radial nerve. It sends upwards, on the posterior aspect of the humerus, and along the medial margin of the groove, a Medial epi- condyle FIG. 36. — Dorsal aspect of the Humerus with Attachments of Muscles mapped out. DORSUM OF THE ARM 85 narrow pointed fleshy slip, which obtains origin from the bone as high as the insertion of the teres major muscle. Below, it widens out and arises, by short fibres, from the entire breadth of the posterior surface of the humerus. It also springs from the posterior surface of the medial intermuscular septum, and from the lower part of the corresponding surface of the lateral intermuscular septum. The medial head of the triceps, therefore, has very much the same origin from the back of the bone that the brachialis has from the anterior surface of the bone. The dissector should now study the common tendon of insertion of the triceps. The long and the lateral heads end in a broad, flat tendon, which is inserted into the back part of the proximal surface of the olecranon, and at the same time gives off, on the lateral side, a strong expansion to the fascia of the forearm as it covers the anconaeus muscle. The short fleshy fibres of the medial head are, for the most part, inserted into the deep surface of the common tendon, but a considerable number find direct attachment to the olecranon, whilst a few of the deepest fibres are inserted into the loose posterior part of the capsule of the elbow-joint. These latter fibres have been described as a separate muscle under the name of subanconceus. . The triceps is supplied by branches from the radial nerve. Dissection.— In order that the radial nerve and the art. profunda brachii may be fully exposed, the lateral head of the triceps must be divided. Thrust the handle of a knife along the sulcus for the radial nerve, and under the muscle. This will give the direction in which the lateral head of the triceps should be severed. Beyond cleaning the nerve and its branches, and the art. profunda brachii, as they lie in the groove, no further dissection is necessary. Nervus Radialis (O.T. Musculo-Spiral Nerve). — The radial nerve is the direct continuation of the posterior cord of the brachial plexus after it has furnished in the axilla the two subscapular nerves, the thoracodorsal nerve, and the axillary nerve. In the first instance, the radial nerve proceeds distally, behind the distal part of the axillary artery and the proximal part of the brachial artery. It soon leaves the anterior aspect of the arm, however, and, inclining backwards, with the art. profunda brachii, enters the interval between the long and the medial heads of the triceps, and reaches the sulcus for the radial nerve. In this it passes round the back of the body of the 1—6* 86 THE UPPER EXTREMITY humerus, under cover of the lateral head of the triceps, and on the lateral side of the limb it pierces the lateral intermuscular septum and appears in the anterior compartment of the arm. Spine of scapula A. trans, scapulae (O.T. suprascapular) M. supraspinatus M. infraspinatus A. circumflex, scap. (O.T. dorsalis , scap.) M. teres minor f- M. subscapularis - M. teres major / Triang. space Quadrangular space M. triceps cap. long. N. radialis (O.T. musculo-spiral) N. suprascapularis M. deltoideus A. brachialis M. triceps, cap. lat. - N. to m. triceps, cap. med. -- M. triceps, cap. med. N. ulnaris ... Epicond. med. --• N. flex. carp, uln J Olecranon ... Bursa subacromalis M. infraspinatus Capsular artic. Articulat. humeri ; N. to m. teres minor M. deltoideus N. axillaris (O.T. circumflex) ram. sup. N. axillaris, ram. inf. N. cutan. brach. lat. M. triceps, cap. lat. N. radial is (O.T. musculo-spiral) A. prof, brachii ram. ant. A. prof, brachii ram. post. N. cut. antib. dorsalis M. brachialis Epicond. lat. A. inteross. recurr. M. anconaeus Mm. ext. dig. comm. et dig. quint. M. ext. carp, ulnaris FIG. 37. — Dissection of the dorsal aspect of the Arm. The lateral head of the Triceps has been divided and turned aside to expose the sulcus on the Humerus for the radial nerve. Here it has already been exposed. It lies deeply in the interval between the brachialis on the medial, and the brachioradialis and extensor carpi radialis longus on the lateral side. It ends at the level of the lateral epicondyle of DORSUM OF THE ARM 87 the humerus by dividing into two terminal branches, viz. the ramus superficialis (O.T. radial) and the ramus profundus (O.T. posterior interosseous). The radial nerve presents, therefore, very different relations as it is traced from its origin to its termination: (i) between the subscapularis, latissimus dorsi, teres major, and long head of the triceps which support it behind, and the axillary and brachial arteries which are placed in front of it ; (2) between the long and the medial heads of the triceps ; (3) in the sulcus for the radial nerve between the bone and the lateral head of the triceps ; (4) in the interval between the brachialis on the medial, and the brachioradialis and extensor carpi radialis longus on the lateral side. The branches which proceed from the radial nerve are muscular, cutaneous, and terminal. The cutaneous branches are two in number, and have already been traced. They are — (i) the n. cutaneus brachii posterior, and (2) and (3) the nervi cutanei antibrachii dorsales. The muscular branches are distributed to the three heads of the triceps, to the anconaeus, to the lateral fibres of the brachialis, to the brachic-radialis, and to the extensor carpi radialis longus. The branches to the three last-named muscles spring from the trunk of the nerve after it has pierced the lateral intermuscular septum. The branch to the medial head of the triceps is a long slender nerve, termed the ulnar collateral nerve, on account of its association with the ulnar nerve in the arm. The branch to the anconaeus is a long slender twig which passes through the substance of the medial head of the triceps on its way to the anconaeus (Fig. 37). The terminal branches are the ramus superficialis (O.T. radial), which is a purely cutaneous nerve, and the ramus profundus (O.T. posterior interosseous), which is continued into the dorsal part of the forearm as the dorsal interosseous nerve, and is distributed to the muscles on the dorsal aspect of the forearm, and to the radiocarpal joint. These nerves will be followed later. Arteria Profunda Brachii (O.T. Superior Profunda Artery). —This artery has been already observed to take origin from the brachial trunk, immediately below the lower margin of the teres major muscle. It accompanies the radial nerve and its relations to the three heads of the triceps and the sulcus for the radial nerve of the humerus are exactly the same as i— 6& 88 THE UPPER EXTREMITY those of the nerve. Before it reaches the lateral inter- muscular septum, it ends by dividing into two terminal branches — an anterior and a posterior. The anterior and smaller branch accompanies the radial nerve through the septum, and follows it distally to the anterior aspect of the lateral epicondyle of the humerus, where it anastomoses with the radial recurrent arteries. The posterior larger branch descends on the posterior surface of the lateral intermuscular septum, and anastomoses on the back of the lateral epicondyle of the humerus with the interosseous recurrent artery. The branches which proceed from the art. profunda brachii are chiefly distributed to the three heads of the triceps muscle. One twig ascends between the long and lateral heads of the muscle, and anastomoses with the posterior circumflex artery of the humerus. In this way, a link is established between the axillary and brachial systems of branches. Dissection. — The ulnar nerve, with the superior ulnar collateral artery, and the slender ulnar collateral nerve, can now be advantageously followed, as they proceed distally upon the posterior aspect of the medial inter- muscular septum. They are covered by a thin layer of fleshy fibres belonging to the medial head of the triceps. The posterior branch of the inferior ulnar collateral artery, after it has pierced the medial septum, should also be dissected out. As a rule, a transverse branch passes between this vessel and the posterior terminal part of the a. profunda brachii. It lies upon the posterior aspect of the humerus, immediately above the elbow-joint, and can be exposed by dividing the triceps muscle a short distance above the olecranon. At the same time the fleshy fibres of the medial head of the triceps, which are inserted into the posterior part of the capsule of the elbow-joint, and constitute the subanconaus muscle, should be examined. Lastly, raise the lower piece of the triceps from the elbow-joint, and look for a small bursa mucosa between the deep surface of the triceps tendon and the upper aspect of the olecranon. ARTICULATIO HUMERI (SHOULDER-JOINT). Before proceeding to the dissection of the forearm it is advisable to study the articulatio humeri (shoulder-joint), because if this is deferred too long the ligaments are apt to become dry. In no joint in the body is the movement so free, and so varied in its character, as in the shoulder-joint. This is rendered necessary by the many functions which are performed by the upper limb. Freedom of motion is provided for in two ways— (i) by the large size of the head of the humerus, in comparison with the small dimensions and shallow character ARTICULATIO HUMERI 89 of the glenoid cavity — the socket in which it moves ; (2) by the great laxity of the ligamentous structures which connect the humerus with the scapula. These provisions for allowing an extensive range of movement at this articulation might, at first sight, lead one to doubt the security of the joint. Its strength certainly does not lie in the adaptation of the bony surfaces to one another, nor in the power of its ligaments. It lies — (i) in the intimate manner in which the scapular muscles are arranged around it ; (2) in the overhanging coraco-acromial arch which forms, as it were, a secondary socket for the head of the humerus, and effectually prevents any displace- ment in an upward direction ; and (3) in atmospheric pressure, which Supraspinatus Scapuh Subscapularis Serratus anterior Capsule of joint Humerus Deltoid Fold of capsule of joint Posterior circumflex artery of humerus and axillary (O.T. circumflex) nerve Teres major Radial (O.T. musculo-spiral) nerve Latissimus dorsi FIG. 38. — -Coronal or vertical transverse section through the Left Shoulder-joint. (Viewed from behind. ) exercises a powerful influence in keeping the opposed surfaces in contact with each other. From all points of view, except over a small area below, the loose, ligamentous capsule which envelops the shoulder-joint is supported by muscles, the tendons of which are more or less intimately connected with it. Above, it is covered by the supraspinatus ; behind, the infraspinatus and teres minor are applied to it ; in front is the subscapularis. Below, the capsule is to a certain extent unsupported by muscles, and here it is prolonged downwards, in the form of a fold, in the ordinary dependent position of the limb (Fig. 38). When, however, the arm is abducted, this fold is obliterated, and the head of the bone rests upon the inferior part of the capsule, which now receives partial support from two muscles which 90 THE UPPER EXTREMITY are stretched under it3 viz. the long head of the triceps and the teres major. Still, this must be regarded as the weakest part of the joint, and consequently dislocation of the head of the humerus downwards into the axilla, through the inferior part of the capsule is an occurrence of considerable frequency. Dissection, — Detach the axillary vessels and brachial nerves from the coracoid process to which they have been tied, and throw them distally. Then proceed to remove the muscles. Divide the conjoined origin of the short head of the biceps brachii and the coraco-brachialis close to the coracoid process, the teres major about its middle, and the long head of the triceps about an inch or two below its origin, and turn them aside. Next deal with the muscles more immediately in relation to the joint, viz. the supra- spinatus, the infraspinatus, the teres minor, and the subscapularis. These must be removed with great care, because their tendons are closely con- nected with the subjacent ligamentous capsule. They are not incorporated with the capsule, however, although at first sight they appear to be so, and thus they can be dissected from it. In the case of the subscapularis a protrusion of the synovial membrane, forming a bursa mucosa, will be found near its upper border, close to the root of the coracoid process. The capsule of the shoulder-joint may now be cleaned, and its attachments defined. The ligaments in connection with the shoulder- joint are : — 1. The capsula articularis. 3. The lig. glenohumerale. 2. The lig. coracohumerale. | 4. The labrum glenoidale. Capsula Articularis (Capsule). — The capsule of the shoulder-joint is a dense and strong ligamentous structure, which envelops the articulation on all sides. It is attached to the scapula around the glenoid cavity, but only above is it directly fixed to the bone. Elsewhere it springs from the fibrous ring or the labrum glenoidale, which serves to deepen the articular cavity ; indeed, in its lower part it appears to be continuous with the border of the labrum glenoidale. Laterally it is fixed to the lateral part of the anatomical neck of the humerus. The width of the capsule is not uniform throughout. It expands as it passes over the en- closed head of the humerus, and contracts as it reaches its scapular and humeral attachments. The great laxity of the capsule of the shoulder-joint will now be apparent. When the muscles are removed, and air is admitted into the joint, the bony surfaces fall away from each other — the head of the humerus sinking downwards, when the part is held by the scapula, to the extent of an inch. The capsule of the shoulder-joint is not complete upon all aspects. Its continuity is interrupted by two, and sometimes three, apertures. The largest of these is an opening of some size, which is placed upon its medial aspect, near the root ARTICULATIO HUMERI 91 of the coracoid process. Through this aperture an exten- sive protrusion of the synovial membrane takes place in the form of a bursa mucosa, which, from its position under the upper part of the subscapularis muscle, receives the name of the bursa subscapularis. It is important to note the position and character of this opening, seeing that in some cases the head of the bone may be driven through it in dislocation of the joint. The second aperture is smaller and more distinctly defined. It is placed between the two tubercles of the Coraco-acromial ligament Coracoid process Acromion process Coraco-humeral ligament Communication between joint- cavity and sub- scapular bursa Capsule of joint : FIG. 39. — Shoulder-joint as seen from the front. humerus, at the proximal part of the sulcus intertubercularis, and it is through this that the long tendinous head of the biceps brachii gains admission to the interior of the capsule. The synovial membrane also protrudes from this opening, and lines the sulcus intertubercularis as low as the in- sertion of the pectoralis major. It is not often that the third opening is seen. It is situated, when present, on the lateral or posterior aspect of the capsule, and allows a pocket of synovial membrane to bulge out in the form of a bursa under the infraspinatus muscle. At certain points the capsule of the shoulder-joint is 92 THE UPPER EXTREMITY specially thickened by the addition of fibres, which pass from the scapula to the humerus. Two of these thickened portions receive the names of the coraco-humeral and the gleno-humeral ligaments. A third is placed on the inferior aspect of the capsule, where it is not supported by muscles, viz. between the long head of the triceps and the subscapularis. It is against this thickened portion of the capsule that the head of the humerus rests when the arm is abducted from the side, and it is sometimes spoken of as the inferior gleno- humeral ligament. Ligamentum Coracohumerale (Coraco-Humeral Ligament). — This is placed upon the proximal aspect of the joint. It is a broad band of great strength, which is more or less completely incorporated with the capsule. Above, it is fixed to the root and lateral border of the coracoid process of the scapula, and it passes from this obliquely distally and laterally, to gain attachment to the. two tubercles of the humerus. It forms a strong arch over the upper part of the sulcus inter- tubercularis, under which the tendon of the biceps passes. Ligamentum Glenohumerale (Gleno- Humeral Ligament). — This ligament can only be seen when the joint is opened. The dissector should therefore, at this stage, remove the posterior part of the capsule, and, drawing the bones well apart from each other, look forwards into the cavity. The tendon of the biceps will be observed arching over the head of the humerus, to reach its insertion on the upper aspect of the glenoid cavity. Immediately medial to this, and parallel to it, will be noticed a ridge on the inner aspect of the capsule projecting into the joint. This band is the gleno- humeral ligament (of Flood). It is inserted into a faintly- marked pit on the anatomical neck of the humerus, close to the upper end of the sulcus intertubercularis. As already noted, the thickened band in the inferior part of the capsule is sometimes called the inferior gleno-humeral ligament. Another thicken- ing of the anterior wall of the capsule between this and the gleno-humeral ligament proper has received the name of the middle gleno-hiimeral ligament. Dissection. — Complete the division of the capsular ligament, and draw- ing the tendon of the biceps brachii through the intertubercular aperture in the capsule, separate the two bones from each other. Labrum Glenoidale (Glenoid Ligament). — The labrum glenoidale is the dense fibro- cartilaginous band which ARTICULATIO HUMERI 93 surrounds the margin of the glenoid cavity of the scapula, and is attached to its rim. It deepens, and at the same time serves to extend, the articular socket of the scapula. The intimate connection which it presents with the capsule of the joint can now be studied. Two tendons are also closely associated with it, viz. the long head of the triceps brachii below, and the long head of the biceps brachii above. Conoid ligament Trapezoid ligament Coraco-acromial ligament Coracoid process Superior gleno- _ humeral ligament Bursal opening- in capsule Inferior gleno- humeral ligament Glenoid cavity Acromio- clavicular igament Capsule of shoulder- joint Glenoid ligament FIG. 40. — Capsular Ligament cut across and Humerus removed. Long Head of the Biceps. — The long tendon which receives this name is an important factor in the construc- tion of the shoulder -joint. Entering the capsule through the opening between the two tubercles of the humerus, it is prolonged over the head of the bone to the top of the glenoid cavity. Its origin should now be examined. It divides into three portions, viz. a large intermediate part, which obtains direct attachment to the scapula, and two smaller lateral parts, which diverge from each other and blend with the labrum glenoidale. The long head of the biceps brachii, 94 THE UPPER EXTREMITY by its position within the capsule, and in the deep sulcus between the tubercles of the humerus, serves to keep the head of the bone in place, and to steady it in the various movements at the shoulder-joint. The stratum synoviale (the synovial membrane) lines the capsule of the joint, and is reflected from it upon the anatomical neck of the humerus as far as the articular margin of the head of the bone. The bursal protrusion of the bursa sub- scapularis under the tendon of the subscapularis muscle has already been noticed. The tendon of the biceps, as it traverses the joint, is enveloped in a tubular sheath of the membrane, which bulges out through the opening of the capsule in the form of a bursa, which lines the sulcus inter- tubercularis, and receives the name of bursa intertubercularis. Articular Surfaces. — The smooth, glistening articular cartilage, which coats the head of the humerus, is thickest in the centre, and thins as it passes towards the edges. In the case of the glenoid cavity the reverse of this will be noticed. The cartilaginous coating is thinnest in the centre, and becomes thicker as it is traced towards the circumference. Movements at the Shoulder -joint. —The shoulder is a ball-and-socket joint (enarthrosis), and consequently movement in every direction is per- mitted, viz. — (\) flexion, or forward movement ; (?.} extension, or backward movement (checked in its extent by the coraco-humeral ligament) ; (3) abdiiction, or lateral movement (checked by the coraco-acromial arch) ; (4) adduction, or medial movement (limited by the coraco-humeral ligament). In addition to these different forms of angular movement, rotation to the extent of a quarter of a circle and circumduction are permitted. The muscles chiefly concerned in producing these movements are : — flexion — the pectoralis major and the anterior part of the deltoid ; extension — latissimus dorsi, posterior part of the deltoid, and the teres major ; abduction — the deltoid and supraspinatus ; adduction — pectoralis major, coraco-brachialis, teres major, and latissimus dorsi ; rotation medially — subscapularis, pectoralis major, latissimus dorsi, teres major ; rotation laterally — supraspinatus, infraspinatus, and teres minor ; circumduction is produced by the action of different combinations of these muscles. FOREARM AND HAND. Dissection. — The skin has already been removed from the volar and dorsal surfaces of the forearm. It should now be raised from the dorsum of the hand by making incisions along the radial and ulnar borders. This is done in order that the superficial structures in this region may be examined in connection with those of the forearm. Venae Superficiales (Superficial Veins). — On the dorsum of FOREARM AND HAND 95 the hand a plexus of superficial veins will be seen. In de- fining this, care must be taken of the fine cutaneous twigs from the superficial branch of the radial nerve and the dorsal branch of the ulnar nerve. From the lateral part of the venous plexus the large cephalic vein takes origin, whilst from its medial part springs the basilic vein. Both of these vessels have already been traced along the forearm to their termina- tions. While still upon the dorsum of the hand each com- municates with the rami profundi in the palm of the hand. Nervi Cutanei (Cutaneous Nerves). — Several cutaneous nerves have already been traced to the integument of the forearm, viz. the volar and ulnar branches of the medial cutaneous nerve of the forearm to the medial aspect, the lateral cutaneous nerve of the forearm to the lateral region, and the dorsal cutaneous nerve of the forearm from the n. radialis on the dorsal aspect. Some additional twigs make their appearance by piercing the fascia in the distal third of the forearm. 1. The n. cutaneus palmaris of the n. ulnaris, ^ 2. The n. cutaneus palmaris of the n. medianus, | , , 3. The n. cutaneus palmaris of the ramus super- f or ficialis of the n. radialis, J 1. The ramus dorsal manus of the n. ulnaris, 1 ,, , , 2. The ramus superficial of the n. radialis, /or Drsal asPect" Rami Cutanei Palmares (Palmar Cutaneous Nerves). — These are small twigs which supply the skin of the palm. The twig from the ulnar nerve takes origin about the middle of the forearm, but it does not at once pierce the fascia of the forearm. It proceeds distally on the ulnar artery, and becomes superficial immediately proximal to the lig. carpi transversum (anterior annular lig.), and close to the lateral side of the insertion of the flexor carpi ulnaris tendon into the pisiform bone. It is here, therefore, that it must be sought for (Fig. 27, p. 66). The palmar cutaneous branch of the median nerve appears through the deep fascia in the interval between the tendons of the flexor carpi radialis and palmaris longus muscles, immediately above the wrist. It is continued distally into the palm (Fig. 27, p. 66). The palmar branch of the superficial division of the radial nerve runs close to the lateral border of the distal part of the forearm. It does not spring from the trunk of the 96 THE UPPER EXTREMITY superficial division of the radial nerve, but from that branch of it which goes to the lateral margin of the thumb. It is joined by a twig from the lateral cutaneous nerve of the forearm, and proceeds downwards in front of the tendon of the abductor pollicis longus to end in the skin covering the ball of the thumb (Fig. 27, p. 66). Dissection. — In tracing the nerves which appear on the dorsum of the forearm, it will be necessary to remove the skin from the dorsal aspect of the thumb and fingers. The great flap of skin which is still attached at the roots of the fingers may be detached, and an incision can then be made along the middle of the dorsal aspect of each digit. The skin should be carefully raised from each finger in two flaps and thrown laterally and medially. Nervi Cutanei Dorsales (Dorsal Cutaneous Nerves). — The dorsal branch of the ulnar nerve winds round the medial margin of the wrist to reach the dorsum of the hand. It will be found immediately below the prominence formed by the distal end of the ulna, and it at once divides into three main terminal branches. Of these, one runs along the ulnar margin of the dorsum of the hand, and is continued onwards along the medial margin of the little finger. The second branch proceeds towards the cleft between the little finger and the ring finger, and divides into two twigs which supply the contiguous sides of these digits. The third branch joins a twig from the superficial branch of the radial nerve, and the nerve thus formed runs towards the interval between the ring finger and the middle finger, and divides to supply their adjacent margins. Each of these three main branches gives several minute filaments to the integument on the dorsum of the hand (Fig. 28, p. 68). The superficial branch of the radial nerve will be found winding round the lateral margin of the forearm, about two inches proximal to the extremity of the styloid process of the radius. It at once gives off a long twig which proceeds along the radial margin of the hand and thumb. A little farther on it breaks up into four terminal branches, which are distributed as follows : the first supplies the medial side of the thumb ; the second goes to the lateral side of the index finger; the third divides to supply the adjacent sides of the index and middle fingers ; whilst the fourth joins with a twig from the dorsal branch of the ulnar (as already described) to supply the contiguous margins of the middle and ring fingers. FOREARM AND HAND 97 It should be noted that, except in the case of the thumb and little finger, the dorsal collateral nerves do not reach the extremities of the digits. The skin on the dorsum of the second and third phalanges of the digits is chiefly supplied by twigs which proceed backwards, from the palmar collateral branches of the median and ulnar nerves. As already stated, it is from the branch of the superficial division of the radial nerve, which goes to the lateral side of the thumb, that the radial palmar cutaneous nerve arises. Numerous fine filaments are given to the skin on the dorsum of the hand, and a certain amount of crossing of the adjacent ulnar and radial twigs takes place in this locality ; in other words, twigs from the one nerve invade the territory which is occupied by the other nerve. Fascia Antibrachii (Fascia of the Forearm). — The deep fascia which envelops the forearm should now be cleaned by removing the subcutaneous adipose tissue. It is an apon- eurosis of great strength and density. More particularly is this the case on the dorsal aspect of the limb, and also in the distal third of the forearm, where the fleshy bellies of the subjacent muscles give place to the tendons. In its proximal part it receives an accession of fibres from the tendon of the biceps brachii in the form of the lacertus fibrosus. Some fibres are also given to it by the tendon of the triceps. Near the elbow it serves as a surface of origin for the numerous muscles which spring from the epicondyles of the humerus, and from its deep aspect dense septa pass between the fleshy bellies. These partitions are indicated on the surface by a series of white lines. At the wrist it becomes continuous in front with the lig. carpi volare and the tig. carpi transversum (O.T. ant. annular lig.), whilst behind it forms an obliquely placed, thickened band, the lig. carpi dorsale (post, annular lig.). On the dorsum of the hand the deep fascia is thin. VOLAR SURFACE AND MEDIAL BORDER OF THE FOREARM. In this dissection the following structures will be brought under the notice of the student : — 1. The radial and ulnar arteries and their branches. 2. The median and ulnar nerves and their branches. 3. The ramus profundus (O.T. posterior interosseous) and the ramus super - ficialis of the n. radialis. 4. The group of pronator and flexor muscles. VOL. I — 7 98 THE UPPER EXTREMITY Dissection. — With the exception of the palmar cutaneous nerves, the superficial veins and nerves on the volar aspect of the forearm may now be turned aside. The deep fascia should also be removed, and when it is followed round the medial border of the forearm it will be found to be firmly attached to the dorsal border of the ulna. Near the elbow, as already stated, it gives origin by its deep surface to the group of muscles which spring from the medial epicondyle of the humerus. Where this is the case, it should be left in situ. Attempts to dissect it off will only result in laceration of the surface of the subjacent fleshy bellies. The radial artery should be followed out before the muscles are much disturbed, and at the same time the various muscles, covering the volar surface of the radius, and upon which the vessel rests, should be cleaned. Arteria Radialis (Radial Artery). — The radial artery is the smaller of the two terminal branches of the brachial artery, but its direction gives it the appearance of being the continuation of the parent trunk into the forearm. It takes origin in the fossa cubitalis, opposite the neck of the radius, and it proceeds downwards, along the lateral side of the volar aspect of the limb, until it reaches the distal end of the bone. There it turns round the lateral border of the wrist and leaves the present dissection. At first it lies between the pronator teres and the brachioradialis, and is overlapped to some extent on the lateral side by the fleshy belly of the latter muscle (Fig. 41). Lower down it is placed between the brachioradialis on the lateral side and the flexor carpi radialis upon the medial side, and this position it maintains as far as the wrist. Where these muscles are fleshy the artery lies at some depth from the surface; but when the tendons make their appearance it assumes a superficial position, and is merely covered by the integument and fascia. Through- out its whole length it is closely accompanied by the vena comites, and the superficial division of the radial nerve lies along its lateral side in the middle third of the forearm. More proximally, the nerve is separated from the vessel by a slight interval ; whilst distally, the nerve leaves the artery and turns round the lateral margin of the forearm under cover of the brachioradialis. Posteriorly the radial artery is supported by the muscles which clothe and find attachment to the volar surface of the radius. At its origin it rests upon the tendon of the biceps brachii ; next it lies in front of the supinator with some adipose tissue intervening ; thence distally it is in contact with the pronator teres, the thin radial head of the flexor digitorum sublimis, the flexor pollicis longus, the pronator quadratus, and lastly, the distal end of the radius. FOREARM AND HAND 99 The radial artery is usually selected for the determination of the ptdse. By placing the tips of the fingers upon the distal part of the forearm, in the interval between the tendons of the brachioradialis and flexor carpi radialis, the pulsations of the vessel in the living person can readily be felt. Branches of the Radial Artery. — In the forearm the radial artery gives off the following branches, viz. : — 1. The a. recurrens radialis. 2. The a. volaris superficialis. 3. The a. carpeus volaris. 4. Kami musculares. The rami musculares are very numerous, and proceed from the radial artery at irregular points throughout its whole course in the forearm. The arteria recurrens radialis is . a branch of some size. It takes origin close .to the commencement of the radial artery, and in the first instance runs laterally between the brachioradialis and the supinator. Here 'it comes into relation with branches coming from the .radial nerve, and gives off several twigs for the supply of the muscles arising from the lateral epicondyle of the humerus. Somewhat reduced in size, it now turns proximally in the interval between the brachioradialis and brachialis, and ends, in front of the lateral epicondyle of the humerus, by anastomos- ing with the anterior terminal branch of the art. profunda brachii. It may be represented by ..two or more vessels. The ramus volaris superficialis (O.T. art. superficialis volae) is a small, variable branch, which arises a short distance proximal to the wrist, and runs distally to end in the muscles of the ball of the thumb. Sometimes, however, it attains a larger size and a special importance, from its being continued into the palm to complete the superficial volar arch on the lateral side. The ramus carpeus volaris is a minute twig which springs from the radial at the distal border of the pronator quadratus muscle. It runs medially, under cover of the flexor tendons, and joins the corresponding branch of the ulnar artery to form the volar carpal arch. The Ramus Superficialis and the Ramus Profundus of the Nervus Radialis (O.T. Radial and Posterior In- terosseous Nerves). — It has already been noted that the radial nerve ends above the elbow, under cover of the brachio- radialis muscle, by dividing into two terminal branches, i— 7 a ioo THE UPPER EXTREMITY the ramus superficial and the ramus profundus. These nerves may now be studied in so far as they lie on the volar aspect of the forearm. The nervus profundus soon disappears from view by passing backwards on the lateral side of the radius through the fibres of the supinator muscle. The ramus superficial proceeds distally under cover of the fleshy belly of the brachioradialis. In the middle V. cephalic; N. cutan. antib. lat. ^-*^ M. brachior N. radialis ramus superfic. (O.T. radial) M. ext. carp. /^ rad. long. "T* N. cutan. antib. med. N. medianus M. palmaris longi \ N. interosseus dorsahs' (O.T. posterior interosseous) M. ext. dig V, basilica M. supinator M. supinat N. cutan. antib. dorsalis M. anconaeus Tendon m. biceps brachii FIG. 41. — Transverse section through the Proximal Third of the left Forearm. third of the forearm it lies along the lateral side of the radial artery, and then leaves it by winding round the lateral margin of the limb, under cover of the tendon of the brachioradialis. It has been traced in its farther course (p. 96). The ramus superficialis is a purely cutaneous nerve, and gives off no branches until it gains the dorsal aspect of the lower end of the forearm. Muscles. — The muscles on the volar aspect and medial border of the forearm are arranged in a superficial and a deep group. They comprise the flexors of the wrist and fingers, and also the pronators. In the superficial group FOREARM AND HAND 101 are the pronator teres, the flexor carpi radialis, the palmaris longus, the flexor digitorum sublimis, and the flexor carpi ulnaris, in that order from the lateral to the medial side. The fleshy belly of the flexor sublimis only partially comes to the surface ; the chief bulk of it is placed upon a deeper plane than the others. The deep group is composed of three muscles, placed in contact with the bones and interosseous membrane of the forearm, viz. the flexor digitorum profundus in relation to the ulna, the flexor pollicis longus in relation to the radius, and the pronator quadratus closely applied to the lower ends of both bones. Dissection. — The superficial group of muscles should now be dissected. The brachioradialis, which lies along the lateral side of the forearm, may be cleaned at the same time. In the lower part of the forearm the dis- sector will observe that the flexor tendons are enveloped by a loose bursa mucosa as they pass into the palm, under cover of the transverse carpal ligament. A good view of this may be obtained by pulling the tendons upwards. If possible, the sac should be retained uninjured, in order that its full extent may be studied when the palm of the hand is opened up. At this stage it is also well to define the transverse carpal ligament which bridges across the front of the carpus. The tendon of the palmaris longus passes in front of it, whilst close to the pisiform bone the ulnar artery and nerve are placed upon its volar surface, and give the dissector the key to its depth. This vessel, with its accompanying nerve, are bound down to the ligament by a more superficial band of fascia, the ligamentum carpi volare, which passes over them, and which the student is very apt to mistake for the transverse ligament itself. This band of fascia should not be disturbed in the meantime. Common Origin of the Superficial Muscles. — The five muscles which constitute the superficial group are very closely associated with each other at the elbow — indeed, they may be said to arise by a common origin from the front of the medial epicondyle of the humerus. In addition to this they all derive fibres from the investing deep fascia of the limb, near the elbow, and from the strong fibrous septa which pass between the muscles from the deep surface of investing fascia. The pronator teres, the flexor sublimis, and the flexor carpi ulnaris, have likewise additional heads of origin. M. Pronator Teres (Pronator Radii Teres). — This muscle crosses the proximal half of the front of the forearm obliquely. It arises by two heads, viz. a humeral and an ulnar. The humeral head constitutes the chief bulk of the muscle. It springs from the proximal part of the medial epicondyle of the humerus, and also slightly by fleshy fibres from the distal part of the medial epicondylar ridge. The fascia covering it i— 76 102 THE UPPER EXTREMITY and the fibrous septum on its medial side also contribute fibres. The ulnar head is placed deeply, and it may be recognised from the fact that it intervenes between the median nerve and the ulnar artery. To bring it into view the superficial humeral head must be drawn well to the medial side. The ulnar head is very variable in size. As a rule, it is a small fleshy slip, but sometimes it is chiefly fibrous. It arises from the medial border of the coronoid process of the ulna (Fig. 43, p. 1 08), and soon joins the deep surface of the numeral head. The muscle thus formed is carried obliquely distally and laterally, and ends in a tendon which gains insertion into a rough impression upon the middle of the lateral surface of the radius (Fig. 43, p. 108). This attach- ment is placed on the summit of the chief curve of the radius, an arrangement which enables the muscle to exercise its pronating action at a great advantage. Close to its insertion the pronator teres is crossed by the radial artery and is covered by the brachioradialis muscle. It is supplied by the median nerve. It is a pronator of the forearm and hand and a flexor of the elbow. M. Flexor Carpi Eadialis. — The flexor carpi radialis arises from the common tendon, from the fascia of the forearm and the fibrous septa which intervene between it and the adjacent muscles. Its fleshy belly gives place, a short distance distal to the middle of the forearm, to a long flattened tendon, which, at the wrist, traverses the groove on the front of the os multangulum majus in a special compartment of the trans- verse carpal ligament (Fig. 48, p. 122). It is inserted into the volar aspect of the base of the metacarpal bone of the index, and slightly also into the base of the metacarpal bone of the middle finger. Its relations to the transverse carpal ligament, and also its attachment to the metacarpus, will be exposed and studied at a later stage of the dissection. It is supplied by the median nerve. M. Palmaris Longus. — This is a long slender muscle, which is not always present. It springs from the common origin, the aponeurotic investment of the forearm and the fibrous septum on either side of it. Its tendon pierces the deep fascia immediately proximal to the wrist, and then proceeds distally, in front of the transverse carpal ligament, to join the strong intermediate portion of the palmar aponeurosis. Very frequently it gives a slip to the abductor pollicis brevis. It is FOREARM AND HAND 103 is a flexor of the radio- supplied by the median nerve and carpal and elbow-joints. Pronator teres Flexor carpi radialis Palmaris longus Flexor cligitorum sublimis Palmaris longus Flexor carpi radialis Radial nerve Radial head of flexo digitorum sublimis Median nerve Median artery Radial artery Radial head of flexor digitorum sublimis Flexor pollicis longus Radial artery Abductor pollicis longus FJG. 42. — Dissection of the volar aspect of the Forearm ; the superficial muscles are cut short and turned aside, and the deeper parts are still further displayed by separating the flexor sublimis from the flexor carpi ulnaris along the line of the intermuscular septum which intervenes between them. Triceps Ulnar nerve Olecranon Fibrous arch between heads of flexor carpi ulnaris Ulnar nerve Branch to flexor digitorum pro fund us Branch to flexor carpi ulnaris Flexor digitorum profundus Ulnar nerve Ulnar artery and nerve Dorsal branch of dinar nerve Flexor digitorum profundus Pronator quadratus M. Flexor Carpi Ulnaris. i—7c -This muscle arises by two heads. 104 THE UPPER EXTREMITY One of these is incorporated with the common origin from the medial epicondyle; the other springs from the medial border of the olecranon of the ulna, and likewise by an aponeurotic attachment from the posterior border of the same bone in its proximal two-thirds. Fibres are also derived from the in- vesting fascia and the intermuscular septum on its lateral side. The two heads of origin of the flexor carpi ulnaris bridge across the interval between the medial epicondyle of the humerus and the olecranon, and between them the ulnar nerve is prolonged distally into the forearm. The tendon appears upon the volar border of the muscle, and is inserted into the pisiform bone. The flexor carpi ulnaris is supplied by the ulnar nerve. It is a flexor and adductor of the hand and a flexor of the elbow. M. Flexor Digitorum Sublimis. — The flexor sublimis re- ceives this name from its being placed upon the superficial aspect of the flexor profundus. For the most part it lies deeper than the other superficial muscles (Fig. 41). It is a powerful muscle which arises from the medial epicondyle of the humerus by the common tendon, but it also takes origin from the ulnar collateral ligament of the elbow- joint, from the medial margin of the coronoid process of the ulna, the volar surface of the radius (Fig. 43, p. 108), and the fascial intermuscular septa in relation to it. The radial head of origin is a thin fleshy stratum which is attached to the volar border of the radius from its proximal extremity to a variable distance distal to the insertion of the pronator teres muscle. Four tendons issue from the fleshy mass. These enter the palm by passing under cover of the transverse carpal ligament, and go to the four medial digits. Their insertions will be seen later on, but in the meantime note that at the wrist, and for a short distance above it, they are enveloped by the vagina mucosa previously mentioned, and also that as they pass behind the transverse carpal ligament they lie in pairs — the tendons to the ring and middle fingers being placed on the volar aspect of those for the index and little fingers. The flexor digitorum sublimis is supplied by the median nerve. Dissection. — The ulnar artery" and at the same time the ulnar and median nerves should be followed in their course through the forearm. The artery in the proximal part of its course lies very deeply, but its relations can be fully studied and its branches traced by simply slitting up the intermuscular septum between the flexor digitorum sublimis and the flexor carpi ulnaris. FOREARM AND HAND 105 Arteria Ulnaris (Ulnar Artery). — This is the larger of the two terminal branches of the brachial trunk. It takes origin in the fossa cubitalis at the level of the neck of the radius. In the proximal third of the forearm it inclines obliquely distally and medially, and then it proceeds distally and vertically to the wrist. It enters the palm by passing anterior to the transverse carpal ligament. In the proximal oblique portion of its course the vessel is deeply placed, and is crossed by both heads of the pronator teres, the flexor carpi radialis, the palmaris longus, and the flexor digitorum sublimis. In its distal vertical part it is overlapped on the medial side by the flexor carpi ulnaris, but a short distance above the wrist it becomes superficial, and lies in the interval between the tendon of the flexor carpi ulnaris on the medial side and the tendons of the flexor sublimis on the lateral side. On the transverse carpal ligament it is placed close to the lateral side of the pisiform bone, and is covered by a strong band of fascia, the volar carpal ligament (pp. 101, 121), which lies in front of the transverse ligament. Throughout its entire course it -is accompanied by two vena comites. It has important rela- tionships with the median and ulnar nerves. The median nerve, which lies upon its medial side at its origin, soon crosses it, but as it does so it is separated from the artery by the deep head of the pronator teres. The ulnar nerve in the proximal third of the forearm is separated from the vessel by a wide interval, but in the distal two-thirds of the forearm it closely accompanies the artery, and lies on its medial side. In the fossa cubitalis the ulnar artery rests upon the brachialis ; beyond this it is in contact behind with the flexor digitorum profundus ; whilst at the wrist the artery lies upon the anterior surface of the transverse carpal ligament. Branches of the Ulnar Artery. — In the forearm the ulnar artery gives off the following branches : — 1. A. recurrens ulnaris volaris. 2. A. recurrens ulnaris dorsalis. 3. A. interossea communis. 4. A. carpea volaris. 5. A. carpea dorsalis. 6. Kami musculares. The rami musculares are of small size, and come off at variable points for the supply of the neighbouring muscles. The a. recurrens ulnaris volaris (O.T. anterior ulnar re- current) is the smaller of the two recurrent branches. It runs proximally, anterior to the medial epicondyle of the humerus, in the interval between the pronator teres and the brachialis io6 THE UPPER EXTREMITY muscles, and it anastomoses with the anterior terminal branch of the inferior ulnar collateral artery. The a. recurrent ulnaris dorsalis (O.T. posterior ulnar recurrent) passes medially, under cover of the flexor digitorum sublimis, and then turns proximally, between the two heads of origin of the flexor carpi ulnaris, to gain the interval between the medial epicondyle of the humerus and the olecranon on the dorsal aspect of the limb. Here it comes into contact with the ulnar nerve, and anastomoses with the posterior terminal branch of the inferior ulnar collateral artery and with the superior ulnar collateral artery. It is not uncommon to find the two recurrent arteries arising from the ulnar trunk by a short common stem. The arteria interossea communis is a short, wide trunk, which takes origin immediately below the recurrent branches, about an inch or so below the commencement of the ulnar artery. It proceeds dorsally, and at the proximal margin of the interosseous membrane it divides into two terminal branches, viz. the volar (O.T. anterior] and the dorsal (O.T. posterior) interosseous arteries. The arteries, carpece ulnares are two small arteries, which partially encircle the wrist. The anterior ulnar carpal artery runs laterally, under cover of the tendons of the flexor digi- torum profundus, and anastomoses with the volar carpal branch of the radial artery. From the arch thus formed small twigs are given to the volar aspect of the carpal bones and joints. The dorsal ulnar carpal artery gains the dorsal aspect of the carpus by winding round the medial margin of the limb immediately proximal to the pisiform bone, and under cover of the tendon of the flexor carpi ulnaris. Nervus Ulnaris (Ulnar Nerve). — The ulnar nerve, which was traced in the dissection of the arm as far as the interval between the olecranon and medial epicondyle of the humerus, enters the forearm between the two heads of the flexor carpi ulnaris. It proceeds distally, upon the flexor digitorum pro- fundus and under cover of the flexor carpi ulnaris, along the volar aspect of the medial side of the forearm. Close to the wrist it becomes superficial, upon the lateral side of the tendon of the flexor carpi ulnaris, and it reaches the palm by passing anterior to the transverse carpal ligament. In the proximal third of the forearm the ulnar nerve is separated from the ulnar artery by an interval, but in the distal FOREARM AND HAND 107 two-thirds it is closely applied to the medial side of the vessel. In the forearm the ulnar nerve gives off: — I. Kami articulates. ,. Rami Muscu.ares, 3. Kami cutanei, { The rami articulares come from the ulnar nerve as it lies in the interval between the olecranon and medial epicondyle of the humerus, and pass to the elbow joint. The rami musculares are given off high up in the fore- arm, and supply the flexor carpi ulnaris and the medial part of the flexor digitorum profundus. The ramus cutaneus palmaris is a minute twig which has already been seen piercing the fascia of the forearm im- mediately above the transverse carpal ligament. It arises about the middle of the forearm and proceeds distally upon the ulnar artery, to the coats of which it gives fine filaments. The ramus dorsatis manus is a nerve of some size which springs from the ulnar trunk about two and a half or three inches above the wrist. It winds round the medial margin of the forearm, under cover of the flexor carpi ulnaris, and reaches the dorsum of the hand immediately below the prominence formed by the distal end of the ulna. From this point onwards it has been traced in the superficial dissec- tion (p. 96). Nervus Medianus (Median Nerve). — As its name implies, the median nerve passes down the middle of the forearm ; and to obtain an unbroken view of it, it is necessary to reflect the humeral head of the pronator teres and the radial head of the flexor digitorum sublimis. In the proximal part of the forearm the median nerve lies in the fossa cubitalis upon the medial side of the ulnar artery. It leaves this space by passing between the two heads of the pronator teres, and as it does so it crosses the ulnar artery, but is separated from the vessel by the ulnar head of the muscle. From this point the median nerve runs distally between the flexor sublimis and the flexor digitorum pro- fundus. Near the wrist it becomes superficial, and lies in the interval between the tendons of the flexor digitorum sublimis on the medial and the flexor carpi radialis on the io8 THE UPPER EXTREMITY FIG. 43. — Forearm mapped out. fundus is the large lateral side. Finally it leaves the forearm by passing be- hind the transverse carpal ligament. A small artery, the a. mediana, a branch of the volar interosseous artery, accompanies the median nerve. Sometimes this vessel attains a considerable size. As the median nerve enters the forearm it gives off numerous branches for the supply of muscles, and near the wrist it supplies a ramus palmaris, which has already been dissected (p. 95> The muscular branches supply all the muscles of the superficial group, therefore, with the single exception of the flexor carpi ulnaris ; viz. the pronator teres, the flexor carpi radialis, the palmaris longus, and the flexor digi- torum sublimis. It likewise supplies a long slender twig — volar in- terosseous nerve — which goes to the deep muscles on the anterior aspect of the fore- arm. Deep Structures on the front of the Forearm.— The connections of the deep muscles must now be studied, and at the same time the volar interosseous artery and volar interosse- ous nerve must be followed. The flexor digitorum pro- muscle which clothes the volar and FOREARM AND HAND 109 medial aspects of the ulna; the flexor pollicis longus is placed upon the volar surface of the radius; while the pronator quadratus is a quadrate fleshy layer closely applied to both bones immediately proximal to the wrist. The artery and nerve proceed distally in the interval between the flexor pro- fundus and flexor pollicis longus. M. Flexor Digitonun Profundus. — The deep flexor of the fingers springs from the volar and medial surfaces of the ulna in its proximal three -fourths. It likewise derives fibres from the volar surface of the interosseous membrane and the aponeurosis by which the flexor carpi ulnaris takes origin from the dorsal border of the ulna. The fleshy mass gives place to four tendons for the four medial digits, but only one of these — that for the index finger — becomes separate and distinct in the forearm. They proceed distally, deep to the transverse carpal ligament, into the palm. The flexor digitorum profundus is supplied by the volar interosseous branch of the median and by the ulnar nerve. M. Flexor Pollicis Longus. — The flexor pollicis longus arises from the volar surface of the radius, over an area which extends from the volar border above to the proximal border of the pronator quadratus below. It also takes origin from the adjacent part of the volar surface of the interosseous membrane. A rounded tendon issues from the fleshy belly, and proceeds into the palm, under cover of the transverse carpal ligament. In many cases the flexor pollicis longus will be observed to have an additional slender head of origin, from the medial border of the coronoid process of the ulna, or the medial epicondyle of the humerus. The flexor pollicis longus is supplied by the volar interosseous nerve. M. Pronator Quadratus. — This is a quadrate muscle which takes origin from the volar surface of the ulna in its distal fourth, and is inserted into the volar aspect of the distal end of the radius. It is supplied by the volar interosseous nerve. Arteria Interossea Volaris (O.T. Anterior Interosseous Artery). — The volar interosseous artery has been seen to arise from the common interosseous artery. It runs distally upon the volar surface of the interosseous membrane, in the interval between the flexor pollicis longus and the flexor digitorum profundus. At the proximal border of the pronator no THE UPPER EXTREMITY quadratus it pierces the interosseous membrane, and gains the dorsal aspect of the limb. It supplies rami musculares to the three deep muscles with which it is in contact. In addition to these it gives off the following branches :— 1. Median. 2. Medullary. 3. Anterior communicating. The a. mediana is a long delicate vessel which accom- panies the median nerve. The medullary arteries are two in number — one for the radius, the other for the ulna. They enter the ' nutrient foramina of these bones. The anterior communicating is a slender artery, which runs distally, behind the pronator quadratus, to join the volar carpal arch. Nervus Interosseus Volaris (O.T. Anterior Interosseous Nerve). — This is a branch of the median, and accompanies the artery of the same name. It does not follow it, however, through the interosseous membrane, but is distributed entirely upon the volar aspect of the limb. It is the nerve of supply for the flexor pollicis longus, the lateral part of the flexor digitorum profundus, and the pronator quadratus, whilst its terminal filament proceeds distally, behind the last-named muscle, to help in the supply of the carpal joints. The flexor digitorum profundus is therefore supplied by two nerves, viz. the ulnar and the median. The precise range of supply by each of these nerves is somewhat variable. As a general rule the division of the muscle which belongs to the index finger is supplied by the median and the part belonging to the little finger by the ulnar ; whilst the portions belonging to the middle and ring digits receive filaments from both nerves. WRIST AND PALM. In this dissection we meet with the following structures :— 1. M. palmaris brevis and the volar cutaneous nerves. 2. Aponeurosis palmaris. 3. Arcus volaris superficialis and its branches. 4. Median and ulnar nerves and their branches. 5. Lig. carpi volare, lig. carpi transversum, the flexor tendons, and their vaginae mucosae. 6. Mm. lumbricales. 7. Short muscles of the thumb and little finger. 8. Arcus volaris profundus and its branches. 9. Arteria princeps pollicis and art. volaris indicis radialis. FOREARM AND HAND 1 1 1 Surface Anatomy. — In the centre of the palm the depres- sion, known as the " hollow of the hand," may be remarked. Along the medial border of the palm this is bounded by a A. volaris indicis radialis Ulnar nerve Ulnar artery Princeps pollicis Branch to muscles of thumb Superficial volar artery Median nerve Radial artery FIG. 44. — Diagram of Nerves and Vessels of Hand in relation to Bones and Skin Markings. rounded elevation, called the hypothenar eminence, which is produced by the subjacent short, intrinsic muscles of the little finger. The thenar eminence, or ball of the thumb, formed by the short muscles of that digit, is the marked projection which limits the palmar hollow proximally and on the lateral side ; ii2 , THE UPPER EXTREMITY whilst the transverse elevation above the roots of the fingers, which corresponds to the metacarpo-phalangeal articulations, constitutes the distal boundary of the central palmar depres- sion. Two pronounced bony projections on the front of the wrist cannot fail to attract attention when the hand is bent backwards. The more prominent of the two is situated at the proximal extremity of the thenar eminence, and is formed by the tubercle of the navicular bone and the vertical ridge on the front of the os multangulum majus ; the other is placed at the proximal end of the hypothenar eminence, and is some- what obscured by the soft parts attached to it. It is caused by the pisiform bone, and when taken firmly between the ringer and thumb a slight degree of gliding movement can be communicated to it. Traversing the thick integument of the palm, three strongly marked furrows are apparent. One of these begins at the elevation formed by the navicular and os multangulum, and curves distally and laterally, around the base of the thenar eminence, to the lateral margin of the hand. A second crosses the palm transversely. Commenc- ing at the middle of the lateral border of the hand, where the first furrow ends, it runs medially, but, as a general rule, it fades away upon the hypothenar eminence. The third furrow begins near the cleft between the index and middle fingers, and proceeds medially with a gentle curve across the hypothenar eminence to the medial margin of the hand. The transverse cutaneous furrows at the roots of the fingers, and on the palmar aspects of the interphalangeal joints, should also be noticed. The furrows at the roots of the fingers are placed over the palmar aspects of the proximal phalanges very nearly one inch distal to the metacarpo-phalangeal joints. The proximal of the two furrows palmar to each of the proximal interphalangeal joints is placed immediately over the articulation, whilst in the case of the distal inter- phalangeal joints the single crease which is usually present is situated immediately proximal to the articulation. On the back of the hand the metacarpal bones can be readily felt, whilst their distal extremities, or heads, form the promin- ences known as the "knuckles." Reflection of Skin. — In the first instance the skin should only be raised from the palm. Two incisions are required — viz. (i) a vertical incision along the middle line of the palm ; (2) a transverse cut across the roots of the fingers from the medial to the lateral margin of the hand. The skin is tightly bound down to the subjacent palmar aponeurosis, and it must be FOREARM AND HAND 113 raised with care. More especially is it necessary to proceed with caution at the roots of the fingers in order that some transverse fibres, constituting a superficial cutaneous ligament, may be preserved. In reflecting the medial flap of integument it is well not to lift it quite as far as the medial border of the hand, because it is into this portion of skin that the m. palmaris brevis is inserted. Superficial Structures. — The superficial fascia over the central part of the palm is dense and thin, and the fat is subdivided into small lobules by fibrous septa which bind the skin to the subjacent palmar aponeurosis. Towards the medial and lateral margins of the hand the fat becomes softer, and the amount of fibrous tissue amongst it diminishes. In connection with the superficial fascia of the palm we have to study — (i) the palmaris brevis; (2) the superficial trans- verse ligament ; and (3) the palmar cutaneous nerves. The m. palmaris brevis is a small cutaneous muscle embed- ded in the superficial fascia which covers the proximal part of the hypothenar eminence. If it has not already been exposed by the reflection of the skin, carry the knife transversely through the granular fat on the ulnar margin of the palm immediately below the transverse carpal ligament. The fleshy bundles of the muscle will come into view. When these have been cleaned, the muscle will be seen to consist of a series of distinct fasciculi, which, in its distal part, are frequently separated from each other by intervals of varying width. It constitutes a thin fleshy layer, which covers an inch and a half or more of the hypothenar eminence. Laterally it takes origin from the transverse carpal ligament and medial border of the intermediate part of the palmar aponeurosis whilst medially its fasciculi are inserted into the skin over the medial margin of the hand. The volar (palmar) cutaneous nerves are three in number, and they arise, as already noted, from the ulnar and median nerves and from the superficial branch of the radial nerve. They should now be traced to their ultimate distribution in the palm of the hand. The transverse superficial ligament is a band of fibres which extends across the palm at the roots of the fingers. It is intimately connected with the skin, and is enclosed within the folds of integument in the clefts between the fingers. Dissection. — The palmaris brevis should be reflected by detaching its fasciculi from their origin, and turning them medially. In raising the muscle care must be taken of the ulnar artery and nerve, which lie under VOL. I — 8 n4 THE UPPER EXTREMITY cover of it, and a little filament from the latter nerve should be traced into its substance. The granular fat should next be removed from the palm, and the dense palmar aponeurosis cleaned. Towards the roots of the fingers the Palmaris longus Flexor carpi ulnaris Ulnar artery Lig. carpi transversum (O.T. Anterior annular ligament) Pisiform bone Palmaris longu Palmaris brevi Abductor digiti quinti. Flexor digiti quint brevis Palmar fascia (intermediate part) 4th lumbrical with digital artery and nerves 3rd lumbrical with digital artery and nerves Transverse superficial ligament Flexor sublimis Brachioradialis Flexor carpi radialis Radial artery Median nerve Abductor pollicis longus Volar superficial artery Opponens pollicis Abductor pollicis /l^ i_ Flexor pollicis brevis \ «\ \ ist lumbrical with x digital nerve and arteria radialis indicis nd lumbrical with digital artery and nerves FIG. 45. — Superficial Dissection of the Palm. The intermediate part of the palmar aponeurosis has been left in position whilst the lateral and medial portions have been removed to display the short muscles of the thumb and little finger. digital vessels and nerves, together with the lumbrical muscles, appear in the intervals between the slips into which the palmar aponeurosis divides. These should be defined, and it will be seen that they pass distally under cover of the superficial transverse ligament. Having noted this point, FOREARM AND HAND 115 remove the ligament. The digital arteries and nerves for the medial side of the little finger, and the lateral side of the index, appear beyond the area of the intermediate part of the palmar aponeurosis, more proximal than the others, and are consequently liable to injury, unless the positions they occupy are kept in mind. Aponeurosis Palmaris (O.T. Palmar Fascia). — The palmar aponeurosis is composed of three portions — an intermediate, a medial, and a lateral. The lateral and medial are thin and weak, and are spread over the muscles which constitute the thenar and hypothenar eminences on the lateral and medial margins of the palm. The intermediate portion of the palmar aponeurosis, on the other hand, is exceedingly strong and dense, and is spread out over the middle of the palm. It counteracts the effect of pressure in this region, and effectually protects the vessels, nerves, and tendons over which it is stretched. Its strength differs considerably in different hands, and it is seen to best advantage in the horny hand of a labourer, or of a mechanic who has been in the habit of handling heavy implements. In shape it is triangular. Above, it is narrow and pointed, and at the wrist it is attached to the transverse carpal ligament, and receives the insertion of the flattened tendon of the palmaris longus. As it approaches the heads of the metacarpal bones it expands, and finally divides into four slips, which separate slightly from each other and pass to the roots of the four medial digits. It gives no slip to the thumb. For the most part it is composed of longitudinal fibres, but, where it divides, a series of strong and very evident transverse fibres pass across it in relation to its deep surface, and bind together its diverg- ing slips. In the three intervals between the digital slips of the palmar aponeurosis, the digital arteries and nerves, together with the corresponding lumbrical muscles, make their appear- ance. The connections of the four digital slips of the palmar aponeurosis must be closely examined. Each lies in front of the two flexor tendons proceeding to the finger with which it is connected, and each will be observed to divide into two portions, so as to form an arch under which these tendons pass. This arch is connected with the flexor sheaths, which bind the tendons to the front of the finger, and the two portions which form it are carried backwards, to obtain attachment to the transverse metacarpal ligament, which i— 8 a n6 THE UPPER EXTREMITY stretches transversely across the fronts of the heads of the metacarpal bones. These relations can only be satisfactorily made out by dividing the arch and slitting the slip of fascia in an upward direction. Fascial Compartments of the Palm. — Two weak septa pro- ceed into the palm from the margins of the strong intermediate portion of the palmar aponeurosis. They join a layer of fascia, which is spread out over the interosseous muscles and the deep volar arch, and they thus subdivide the palm into three fascial compartments, viz. an intermediate, containing the flexor tendons, the lumbrical muscles, the superficial volar arch, and the terminal branches of the median nerve; a medial, enclosing the short muscles of the little finger ; and a lateral, enclosing the short muscles of the thumb. Dissection. — Raise the intermediate part of the palmar aponeurosis. Divide its narrow proximal part, throw it distally, and finally remove it completely. The siiperficial volar arch is the most superficial of the struc- tures now exposed. Trace the ulnar artery into it, and follow the digital branches which it gives off. The lig. carpi volare which binds the ulnar artery to the front of the transverse carpal ligament may now be removed. The median and ulnar nerves must also be dissected. The muscular branches, which the median gives to the muscles of the thenar eminence, are especially liable to injury. They come off in a short, stout stem, almost in a line with the lower margin of the transverse carpal ligament, and at once turn laterally to reach the short muscles of the thumb, to some of which they are distributed. The nerve twigs to the two lateral lumbricals must also be looked for. They spring from the digital branches of the median which go to the lateral side of the index and to the cleft between the index and middle fingers. In order that the digital vessels and nerves may be traced to their distribution the skin must be reflected from the fingers. This can be done by making an incision along the middle of each digit, and turning the integument laterally and medially. As the skin is raised from the borders of the different digits the cutaneous ligaments of the phalanges (Cleland) will come into view. These are fibrous bands, which spring from the edges of the phalanges behind the digital vessels and nerves. They are inserted into the skin so as to form a strong fibrous septum on each side of each finger. They retain the integument in proper position during the different movements of the digits. Arcus Volaris Superficialis (O.T. Superficial Palmar Arch). — The ulnar artery, when traced into the palm, is found to form the superficial volar arch — an arterial arcade, which lies immediately subjacent to the palmar aponeurosis. The ulnar artery enters the palm by passing in front of the transverse carpal ligament, close to the lateral side of the pisiform bone. A short distance below this it curves laterally across the palm, and, near the middle of the thenar emin- FOREARM AND HAND 117 ence, it is joined by the superficial volaris branch of the radial, or, more frequently, by a twig from the art. volaris indicis radialis or art. princeps pollicis. The convexity of the arch is directed distally towards the fingers, and its most Flexor ca Ulnar artery_j| Dorsal branch of ulnar nerve Ulnar nerve Deep branch of ulnar nerve Abductor digiti quinti Deep branch of ulnar artery. Superficial part of ulnar nerve Opponens digiti quinti Abductor digiti quinti Flexor brevis digiti quinti 4th lumbrical 3rd lumbrical Flexor digitorum sublimis Flexor carpi radialis Median nerve Radial artery Superficial volar artery .Lig. carpi transversum (O.T. anterior annular lig.) Abductor pollicis longus Abductor pollicis _Opponens pollicis Median nerve Flexor brevis pollicis Abductor pollicis Superficial volar arch (O.T. sup. palmar arch) Adductor pollicis, transverse part. t lumbrical 2nd lumbrical FIG. 46. — The parts in the Palm which are displayed by the removal of the Palmar Aponeurosis. In the specimen from which the drawing was taken the arteria volaris indicis radialis and the arteria princeps pollicis took origin from the arcus volaris superficialis. distal point corresponds with a line drawn across the palm parallel with the distal border of the outstretched thumb. Throughout its entire extent the superficial volar arch lies very near the surface. Its medial part is covered by the i— Sb n8 THE UPPER EXTREMITY palmaris brevis muscle ; beyond this it is placed immediately behind the intermediate part of the palmar aponeurosis. As it is followed from the medial to the lateral side of the hand it will be seen to rest upon — (a) the transverse carpal ligament ; (b] the short muscles of the little finger ; (c) the flexor tendons and the digital branches of the median nerve. Branches of the Arcus Volaris Superficialis. — Small branches proceed from the superficial volar arch for the supply of the integument and adjoining short muscles of the palm. As the ulnar artery leaves the surface of the transverse carpal ligament it gives off its prqfunda branch ; whilst from the convexity of the arch proceed four common volar digital branches. The a. volaris profundus is a small vessel, which at once disappears from view by passing backwards in the interval between the abductor digiti quinti and the flexor brevis digiti quinti. It will be traced to its termination in the deep dissection of the palm. The four common volar digital arteries supply both sides of the three medial digits and the medial side of the index finger. The first common volar digital artery runs distally upon the short muscles of the little finger, to which it gives twigs, and then it is carried along the medial side of the digit. The second common volar digital artery proceeds towards the interval between the roots of the little and ring fingers, and divides into two branches (collateral or proper volar digital arteries\ which run along the contiguous sides of these digits. The ^third common volar digital artery supplies in like manner the adjacent sides of the ring and middle fingers; whilst the fourth common volar digital artery deals similarly with the contiguous margins of the middle and index fingers. There are certain points in connection with these volar digital arteries, during their course in the palm and along the sides of the fingers, which must be noted. In the palm the undivided trunks lie in the intervals between the flexor tendons and volar to the digital nerves and the lumbrical muscles. Along the sides of the fingers they show a different relation to the nerves : the nerves are now on the volar side and the arteries lie dorsal to them. Upon the terminal phalanx the two collateral branches join to form an arch, from which proceed great numbers of fine twigs, to supply the pulp of the finger, and the bed upon which the nail rests. FOREARM AND HAND 119 Each common volar digital artery, at the point at which it divides, is joined by the corresponding volar metacarpal artery from the deep volar arch. The proper volar digital arteries give a liberal supply of twigs to the integument, the sheaths of the tendons, and the joints of the fingers. Nervus Medianus (Median Nerve). — The median nerve enters the palm by passing deep to the transverse carpal liga- ment with the flexor tendons. In this part of its course it is overlapped by the mucous sheath which is wrapped around the tendons. Further, before it emerges it assumes a flattened form, and divides into two portions. Of these, the lateral division is slightly the smaller of the two, and gives off— (i) a stout short branch to some of the intrinsic muscles of the thumb; (2) three digital branches which go to the two sides qf the thumb and the lateral side of the index finger. The muscular branch takes origin at the distal border of the transverse carpal ligament, and at once turns laterally to supply the abductor pollicis, the superficial head of the flexor pollicis brevis, and the opponens pollicis. The proper volar digital nerves which run along the medial side of the thumb, and the lateral side of the index, give several branches to the fold of integument which stretches between the roots of these digits ; whilst the proper volar digital branch to the lateral border of the index gives a minute twig to the first or most lateral lumbrical muscle. The larger medial division of the median nerve divides into two branches. Of these one runs towards the cleft between the index and middle fingers, and splits into the proper volar digital nerves for the adjacent sides of those digits. From this nerve a twig to the second lumbrical muscle is given off. The second common volar digital branch of the medial division of the median proceeds towards the cleft between the middle and ring fingers, and divides into the proper volar digital branches for their contiguous margins. In some instances the latter nerve supplies a twig to the third lumbrical muscle. In the palm the digital branches of the median proceed distally deep to the superficial volar arch, but as they approach the fingers they come to lie volar to the common volar digital arteries, which in many cases may be observed to pass through, or perforate, the nerves. As the proper volar digital nerves lie upon the sides of the fingers, numerous i— 8c 120 THE UPPER EXTREMITY branches are given to the integument ; and if the dissector exercises sufficient patience and care in the dissection, he will notice attached to the nerve twigs numerous minute, oval, seed-like bodies. These are the Pacinian bodies. At the extremity of the fingers each of the proper volar digital nerves divides into two terminal branches. Of these, one ramifies in the pulp, whilst the other inclines dorsally to reach the bed upon which the nail rests. Several twigs pass to the dorsal aspects of the fingers, and these are chiefly responsible for the supply of the integument on the dorsal aspects of the second and third phalanges. Nervus Ulnaris (Ulnar Nerve). — The palmar continuation of the ulnar nerve enters the palm by passing superficial to the transverse carpal ligament. It lies secure from the effects of pressure under the shelter of the pisiform bone, and upon the medial side of the ulnar artery. At this level it divides into two terminal branches — a superficial and a deep. The deep branch is continued distally, upon the transverse carpal ligament, and associates itself with the volar profunda branch of the ulnar artery. It leaves the present dissection by passing dorsally between the abductor and the 'flexor brevis muscles of the little finger. The superficial branch runs distally under cover of the palmaris brevis, to which it gives a branch of supply,' and then divides into two common volar digital branches. One of these proceeds obliquely over the short muscles of the little finger to gain the medial side of that digit ; the other runs distally to the cleft between the little and ring fingers, and divides into the proper volar digital branches for the adjacent sides of those digits. A branch of communication passes from the second common volar digital branch of the ulnar nerve to the adjoining common volar digital branch of the median nerve. The proper volar digital branches of the ulnar nerve are distributed on the sides of the fingers in precisely the same manner as those derived from the median. Lig. Carpi Transversum (O.T. Anterior Annular Liga- ment).— This is a thick, dense, fibrous band, which stretches across the front of the concavity of the carpus, and converts it into an osteo-fibrous tunnel for the passage of the flexor tendons into the palm. On each side it is attached to the two piers of the carpal arch, viz. on the lateral side to the tubercle FOREARM AND HAND 121 of the navicular bone and the ridge of the greater multangular bone, and on the medial side to the pisiform bone and the hook of the os hamatum. Its proximal margin is in a measure continuous with the deep fascia of the forearm, of which it may be considered to be a thickened part ; whilst distally, it is connected with the palmar aponeurosis. Upon the volar surface of the transverse carpal ligament the expanded tendon of the palmaris longus is prolonged distally to the intermediate part of the palmar aponeurosis, whilst on M. palmaris longus N. medianus Lig. carpi transversum M. flex. poll. long. A. volaris superficialis M. flex. carp. rad. \ Short muscles of thumb M. abd. poll. long% A. ulnaris / M. palmaris brevis ' . N. ulnaris M. ext. poll. brev. A. radialis' M. ext. long, poll.' M. ext. carp. rad. long. N. radialis rain, su Short muscles of little finger (O.T. radial) M. ext. carp. rad. bre1 ^TYs ^' ex^* carP- ul M. ext. dig. quinti N. ulnaris, ramus dorsalis M. ext. dig. comm. and ext. indicis FIG. 47. — Transverse section through the Wrist at the level of the Distal Row of Carpal Bones to show the Carpal Tunnel. The Tendons of the Flexor Digitorum Sublimis, Flexor Digitorum Profundus, and Flexor Pollicis Longus are seen within the Tunnel. each side several of the short muscles of the thumb and little ringer take origin from it. Close to its medial attachment the ulnar artery and nerve find their way into the palm by pass- ing superficial to it and deep to a more superficial fasciae band, the ligamentum carpi volare, which is attached on the medial side to the pisiform and the hook of the os hamatum, and on the lateral side to the tubercle of the navicular and the ridge of the great multangular bone. The tunnel which the transverse carpal ligament forms with the volar concavity of the carpus is transversely oval in shape, and it opens distally into the intermediate compartment of the palm. Through it pass the tendons of the flexor 122 THE UPPER EXTREMITY digitorum sublimis, the flexor digitorum profundus, the tendon of the flexor pollicis longus, and the median nerve. The relation of the tendon of the flexor carpi radialis to the transverse carpal ligament is peculiar. It pierces the lateral attachment of the ligament, and proceeds distally in the groove of the os multangulum majus in a special compartment provided with a special mucous sheath. Mucous Sheaths of the Flexor Tendons. — As the flexor tendons and the median nerve pass through the carpal tunnel they are enveloped in two mucous sheaths, which at the same time line the walls of the canal, and thus greatly facilitate the Median nerve Lig. carpi transversunv(O.T. ant. annular lig.) Sheath of flexor pollicis longus . Tendons of flexor digitorum sublimis Tendon of flexor pollicis longus '• > ,^ „ . .. . . „, , ... • j- i- i __ *=T=--*4»iX_ Cavity of synovial sheath Sheath of flexor carpi radialis Tendon of flexor carpi radialis Tendons of flexor digitorum profundus FIG. 48. — Diagram illustrating the relation of the Synovial Sheath to the Flexor Tendons. free play of the tendons behind the transverse carpal liga- ment. As already stated, these sheaths are two in number. One is wrapped around the tendon of the flexor pollicis longus, the other invests the tendons of the flexor digitorum profundus and flexor digitorum sublimis. Both are prolonged proximally into the forearm for an inch or more, and both are carried distally into the palm in the form of diverticula upon the diverging tendons. The diverticula in relation to the tendons which go to the index, middle, and ring fingers, end near the middle of the palm. Those upon the tendons of the thumb and little finger, however, are prolonged distally into the digits, and line the fibrous sheaths which confine the tendons upon the volar aspects of the phalanges. It is not likely that these mucous sheaths have been preserved intact throughout the previous dissection of forearm and palm ; but should they FOREARM AND HAND 123 turn out to be uninjured, a very striking demonstration may be obtained by inflating them with air by means of the blowpipe. The apertures through which the air is introduced should be made at the proximal margin of the transverse ligament. It is said that the mucous sheath which invests the tendons of the flexor digitorum sublimis and flexor digitorum profundus is divided by a vertical partition into two compartments, and that the lateral of these communicates, by means of a small aperture near the upper border of the transverse carpal liga- ment, with the mucous sheath of the tendon of the flexor pollicis longus. Flexor Tendons. — Open the carpal tunnel by making a vertical incision through the transverse carpal ligament at its middle. The arrangement of the flexor tendons can now be studied, and the mucous sheath dissected from the surface of each. The tendon of the flexor pollicis longus occupies the lateral part of the canal, and gaining the palm turns laterally to reach the phalanges of the thumb. The four tendons of the flexor sublimis are arranged in pairs behind the transverse carpal ligament; those for the little and the index fingers lying dorsal to those for the ring and middle fingers. Of the tendons of fat flexor profundus ^ only that for the index finger is distinct and separate ; the other three, as a rule, remain united until they emerge from under cover of the transverse carpal ligament. In the central compartment of the palm the flexor tendons diverge from each other, and two, viz. one from the flexor sublimis, and one from the flexor profundus, go to each of the four fingers. From the tendons of the flexor profundus the lumbrical muscles take origin, and these, with the common volar digital nerves and arteries, will be seen occupying the intervals between the tendons as they approach the roots of the fingers. In the fingers the two flexor tendons run distally upon the -velar aspects of the phalanges, and are held in position by the flexor sheaths. These, therefore, must be studied be- fore the insertions of the tendons can be examined. Flexor Sheaths. — Immediately subjacent to the skin, the superficial fascia and the proper volar digital arteries and nerves lie the fibrous sheaths which bind the flexor tendons to the volar surfaces of the phalanges and to the volar accessory ligaments of the metacarpo-phalangeal and inter- I24 THE UPPER EXTREMITY phalangeal joints. Each fibrous sheath consists of a number of parts of which the two strongest, the digital vaginal ligaments, lie opposite the bodies and are attached to the margins of the first and second phalanges. Such strong bands placed opposite the metacarpo-phalangeal and interphalangeal joints would seriously interfere with their movements, therefore, in these regions weaker transverse bands, the annular liga- ments, are formed. In addition cruciate bands — the cruciate ligaments — are often found, intervening between the annular ligaments and the stronger portions of the sheaths. The fibrous sheath, together with the phalanges and the volar accessory liga- ments of the metacarpo- phalangeal and interphalan- geal joints, forms, in each finger, an osteo-fibrous canal, in which are enclosed the tendons of the flexor digi- torum sublimis and of the flexor digitorum profundus together with their surround- ing mucous sheath. The fibrous sheaths in front of one or more of the fingers may now be opened. FIG. 49. — Diagram to illustrate the ar- They will be seen to be lined rangement of the Synovial Sheaths of b a mucous sheath, which is the Flexor Tendons. J reflected over the enclosed tendons so as to give each a separate investment. The mucous sheath of the little finger has been seen to be a direct pro- longation from the common mucous sheath of the flexor tendons ; the other three are distinct from this, and are carried proximally into the palm. They envelop the tendons of the ring, index, and middle fingers, as far as a line drawn across the palm immediately proximal to the heads of the metacarpal bones. If the flexor tendons be raised from the phalanges certain mucous folds will be noticed connecting them to the bones. These are termed the vincula tendina. Of these we dis- FOREARM AND HAND 125 tinguish two kinds, viz. vincula brevia and longa. In the accompanying illustration (Fig. 50) the connections of these may be seen. The vincula brevia are triangular folds, which connect the tendons near their insertions to the volar aspect of the adjacent phalanx. The vincula longa are not invariably present. They are placed more proximally, and are narrow, weak folds which pass between the tendons and the bones. Insertions of the Flexor Tendons. — The insertions of the two flexor tendons can now be studied. On the volar side of the first phalanx the tendon of the flexor sublimis becomes flattened and folded round the subjacent cylindrical tendon of the flexor profundus. It then splits into two parts, which pass dorsal to the tendon of the flexor profundus, and allow Lateral interphalangeal _-— ^ ^.Flexor sheath ligament- Lateral metacarpo- phalangeal ligament _ 7 ^*^**^. brevia Ligamenta longa FIG. 50. — Flexor Tendons of the Finger with Ligg. vaginalia. the latter to proceed onwards between them. Dorsal to the deep tendon the two portions of the tendon of the flexor sublimis become united by their margins, and then they diverge, to be inserted into the borders of the body of the second phalanx.1 By this arrangement the flattened tendon of the flexor sublimis forms a ring, or short tubular passage, through which the tendon of the flexor profundus proceeds onwards to the base of the ungual phalanx, into which it is inserted. In each of the four fingers the same arrangement is found ; the tendon of the flexor sublimis is inserted by two slips into the margins of the volar surface of the second phalanx, whilst the tendon of the flexor profundus is in- serted into the volar aspect of the base of the terminal phalanx. 1 Where the margins of the two slips of the tendon of the flexor sublimis are united behind the tendon of the flexor profundus, a decussation of fibres takes place between the two slips. 126 THE UPPER EXTREMITY Tendon of the Flexor Pollicis Longus. — This tendon pro- ceeds distally, in the interval between two of the muscles of the thumb (viz. the superficial head of the flexor pollicis brevis, and the oblique part of the adductor pollicis), and also in the interval between the two sesamoid bones which play upon the head of the metacarpal bone. Reaching the proximal phalanx, it enters a fibrous sheath constructed upon a similar plan to those of the fingers. When this is opened the tendon will be observed to be inserted into the volar aspect of the base of the terminal phalanx of the thumb. The mucous sheath which surrounds the tendon during its passage through the carpal tunnel is continuous with the sheath which invests the tendon in front of the phalanges. Dissection. — Throw distally the superficial volar arch. Divide it on the medial side distal to the origin of the profunda artery of the palm, and on the lateral side at the point where it is joined by the superficial volar artery. The median nerve may also be severed and its branches turned aside, but care should be taken to preserve the two branches which it gives to the lumbrical muscles, and also the stout branch which enters the muscles of the thenar eminence. Lastly, cut through the fleshy belly of the flexor digitorum sublimis in the forearm, and, raising its tendons from the carpal hollow, throw them as far distally as possible. The tendons of the flexor digitorum profundus and the attached lumbrical muscles are now fully displayed. Mm. Lumbricales. — These are four slender fleshy bellies which arise from the tendons of the flexor digitorum pro- fundus as they traverse the palm. The first lumbrical arises from the lateral side of the tendon for the index finger ; the second lumbrical springs from the lateral border of the tendon for the middle finger ; whilst the third and fourth lumbricals take origin from the adjacent sides of the tendons between which they lie (viz. the tendons for the middle, ring, and little fingers). The little muscles pass distally and end in delicate tendons on the lateral sides of the fingers. Each is inserted into the lateral margin of the dorsal expansion of the extensor tendon, which lies upon the dorsal aspect of the proximal phalanx. Dissection. — The flexor digitorum profundus may be divided in the fore- arm and thrown distally. Great care must be taken in raising the tendons and lumbrical muscles from the palm, because slender twigs from the deep branch of the ulnar nerve enter the two medial lumbrical muscles on their dorsal aspects. These can easily be secured if ordinary caution be observed. The deep volar arch and the deep branch of the palmar part of the ulnar nerve are now exposed, and a favourable opportunity is given for studying the short muscles of the thumb and little finger. FOREARM AND HAND 127 Short Muscles of the Thumb. — The abductor pollids forms the most prominent and lateral part of the ball of the thumb. The superficial head of the flexor pollids brevis lies immediately to the medial side of the abductor ; and by separ- ating the one from the other, the opponens pollids will be exposed. These three muscles lie to the lateral side of the tendon of the flexor pollicis longus. To the medial side of this tendon, and placed deeply in the palm, is a fan-shaped muscular sheet, the adductor pollids, imperfectly separated into a proximal and distal part by the radial artery as it enters the palm. The proximal is the oblique and the distal the trans- verse part of the muscle. In dissecting these muscles the muscular branch of the median nerve must be traced to those which lie upon the lateral side of the long flexor tendon of the thumb, and the deep branch of the ulnar must be followed, and its branches to the adductors of the thumb secured. The abductor pollids arises from the volar aspect of the transverse carpal ligament and the os multangulum majus. It is inserted into the lateral side of the base of the proximal phalanx of the thumb, and slightly into the extensor tendon on the dorsum of the proximal phalanx. Its nerve of supply comes from the median. The superficial head of the flexor pollids brevis1 takes origin from the transverse carpal ligament, and is inserted into the lateral side of the base of the proximal phalanx of the thumb. It is supplied by the median nerve. The opponens pollids springs from the transverse carpal ligament and the ridge on the front of the os multangulum majus. Its fibres spread out, and are inserted into the entire length of the lateral border and the adjacent part of the volar surface of the metacarpal bone of the thumb. Its nerve of supply is derived from the median. The adductor pollids consists of two parts, an oblique part (O.T. oblique adductor pollicis) and a transverse part (O.T. the transverse adductor pollicis). The oblique part arises from the os multangulum minus, the os capitatum, and the bases of the second and third metacarpal bones. The transverse part springs from the lower two-thirds of the volar border of the third metacarpal bone. The two parts con- 1 The term superficial head, applied to this muscle, suggests the presence of a deep head. Such a head is present. It is the interosseus primus volaris of Henle (v. p. 147). 128 THE UPPER EXTREMITY verge laterally, along the medial side of the tendon of the flexor pollicis longus, and they are inserted together into the medial side of the base of the proximal phalanx of the thumb. A strong slip will generally be seen to deviate laterally from the lateral border of the muscle. This passes dorsal to the long flexor tendon, and joins the superficial head of the flexor pollicis brevis. Both parts of the adductor pollicis are supplied by the deep branch of the ulnar nerve. Os lunatum Os capitatum Os multangulum minus Os naviculare manus Abductor pollicis Os multangulum majus Opponens pollicis Abd. pollicis longus Flexor carpi radialis M.I. Adductor polli s hamatum Os triquetrum Flexor carpi ulnaris •Os pisiforme Abductor digiti quinti Flexor brevis digiti quinti Flexor carpi ulnaris Opponens digiti quinti Palmar interossei FIG. 51. — Volar aspect of the Bones of the Carpus and Metacarpus with Muscular Attachments mapped out. Two sesamoid bones are developed in connection with the tendons of the short muscles of the thumb as they are inserted on either side of the base of the proximal phalanx. Short Muscles of the Little Finger. — The abductor digiti quinti (O.T. minimi digiti] lies on the medial and volar aspect of the hypothenar eminence, and the flexor digiti quinti brevis (O.T. minimi digiti] upon its lateral side. On separating these from each other, the Opponens digiti quinti (O.T. minimi digiti] is seen on a deeper plane, and in the interval between them. The abductor digiti quinti arises from the pisiform bone, FOREARM AND HAND 129 and is inserted into the medial side of the base of the proximal phalanx of the little finger. It is supplied by the deep branch of the ulnar nerve. ' The flexor digiti quinti brevis is composed of a single fleshy belly which springs from the hook of the os hamatum and the transverse carpal ligament, and is inserted into the medial side of the proximal phalanx of the little finger, in common with the abductor. This muscle is sometimes much reduced in size, and frequently more or less completely incorporated with the opponens. Its nerve supply comes from the deep branch of the ulnar nerve. The opponens digiti quinti arises from the transverse carpal ligament, and the hook of the os hamatum, and its fibres spread out to obtain insertion into the entire length of the medial margin of the metacarpal bone of the little finger. The deep branch of the ulnar gives it its nerve of supply. Ramus Profundus Nervi Ulnaris (Deep Branch of the palmar part of the Ulnar Nerve). — This nerve springs from the parent trunk on the volar aspect of the transverse carpal ligament, and gives off a branch which supplies the three short muscles of the little finger. Accompanied by the deep branch of the ulnar artery it sinks into the interval between the abductor and flexor digiti quinti brevis, and turns laterally across the palm deep to the flexor tendons. Near the lateral border of the palm the deep branch of the ulnar nerve breaks up into terminal twigs which supply the adductor pollicis, and the first dorsal interosseous muscle. In its course across the palm it lies along the concavity or proximal border of the deep volar arch, and sends three fine branches distally in front of the three interosseous spaces. They supply the inte-rosseous muscles in the spaces, while the two medial also give branches to the dorsal surfaces of the two medial lumbrical muscles. The third lumbrical has frequently a double nerve supply, a branch from the deep part of the ulnar nerve, and, not uncommonly, a second twig from the median enters its volar aspect. The deep branch of the ulnar may, therefore, be said to supply all the muscles of the palm which lie to the medial side of the tendon of the flexor pollicis longus, whilst the median supplies the three muscles which lie to the lateral side of that tendon. There are two exceptions to this generalisation, viz. the two lateral lumbrical muscles, which lie upon the medial VOL. i — 9 130 THE UPPER EXTREMITY side of the tendon, and are yet supplied by the median nerve. Arcus Volaris Profundus (O.T. Deep Palmar Arch).— The artery which takes the chief part in the formation of this arch is the radial. This vessel enters the palm by passing to the volar surface through the proximal part of the first interosseous space between the two heads of the first dorsal interosseous muscle. In the present state of the dissection it makes its appearance between the contiguous margins of the oblique and transverse portions of the adductor pollicis. It runs medially upon the interossei muscles and the meta- carpal bones immediately distal to their bases. As it ap- proaches the fifth metacarpal bone it is joined by the deep volar branch of the ulnar artery, and in this manner the deep volar arch is completed. The deep volar arch does not show so strong a curve as the superficial volar arch, and it is placed at a more proximal level in the palm. It is closely accompanied by the deep branch of the ulnar nerve ; and is separated from the super- ficial volar arch by the group of flexor tendons and their sheaths, the lumbrical muscles, the branches of the median nerve which occupy the intermediate compartment of the palm, and also, at its medial end, by the short flexor of the fifth digit, dorsal to which the deep volar branch of the ulnar artery passes to join the radial. The branches which spring from the deep volar arch are : (i) the recurrent — a few small twigs which run proximally in front of the carpus to anastomose with branches of the volar carpal arch ; (2) perforating branches, which pass dorsally in the upper parts of the interosseous spaces to anastomose with the dorsal metacarpal arteries ; and (3) the volar metacarpal branches — three in number — which pass distally, volar to the interosseous spaces, and unite, near the roots of the fingers, with the corresponding common volar digital arteries from the superficial volar arch. Sometimes these branches enlarge and take the place of the corresponding common volar digital arteries. Dissection. — To bring the arteria volaris indicis radialis and the arteria princeps pollicis into view, the parts of the adductor pollicis must be detached from their origins and turned laterally. The radial artery is now seen passing volarwards between the two heads of the first dorsal interosseous muscle. FOREARM AND HAND 131 Arteria Volaris Indicis Radialis, and Arteria Princeps Pollicis (O.T. Radialis Indicis and Princeps Pollicis Arteries). — These arteries spring from the radial as it proceeds towards the volar surface between the first and second metacarpal bones. The arteria volaris indicts radialis runs distally between the transverse part of the adductor pollicis and the first dorsal interosseous muscle to the lateral border of the index, along which it proceeds as its lateral volar proper digital artery. The arteria princeps pollicis takes a course distally and laterally under cover of the oblique part of the adductor pollicis, and gains the volar aspect of the metacarpal bone of the thumb. Here it lies dorsal to the tendon of the flexor pollicis longus, and divides into the volar proper digital arteries of the thumb. These branches make their appear- ance in the interval between the adductor and the superficial head of the flexor pollicis brevis, and are carried distally on either side of the tendon of the long flexor. Surgical Anatomy of the Palm and Fingers. —When an abscess forms in the intermediate compartment of the palm early surgical interference is urgently called for. The dense palmar aponeurosis effectually prevents the passage of the pus to the surface of the palm, whilst an easy route proximally into the forearm is offered to it by the open carpal tunnel, through which the flexor tendons enter the palm. It is absolutely necessary, therefore, that before this can occur the surgeon should make an opening in the palm by means of which the pus can escape. In making such an incision it is important to bear in mind the position of the various vessels which occupy the intermediate compartment of the palm. As previously stated, the level of the superficial volar arch can be indicated by drawing a line transversely across the palm from the distal margin of the outstretched thumb. The deep volar arch lies half an inch more proximally. The volar common digital arteries, which spring from the convexity of the superficial volar arch, run in line with the clefts between the fingers. An incision, therefore, which is made distal to the superficial volar arch and in a direction corresponding to the central line of one of the fingers, may be considered free from danger in so far as the vessels are concerned. The loose mucous sheath which envelops the flexor tendons as they pass deep to the transverse carpal ligament has been noticed to extend proxim- ally into the distal part of the forearm, and distally into the palm. When this is attacked by inflammatory action it is apt to become distended with fluid (thecal ganglion), and the anatomical arrangement of parts at once offers an explanation of the appearance which is presented. There is a bulging in the palm, and a bulging in the distal part of the forearm, but no swelling at all at the wrist. Here the dense transverse carpal ligament resists the expansion of the mucous sheath, and an hour-glass constriction is evident at this level. The fingers are subject to an inflammatory process, termed whitlow, and, in connection with this, it is essential to remember that the flexor fibrous sheath ends on the base of the distal phalanx in each digit, i — 9 a 132 THE UPPER EXTREMITY When the whitlow occurs more distally, in the pulp of the finger, the vitality of the distal part of the ungual phalanx is endangered, but the flexor tendons may be regarded as being tolerably safe. When the inflammation occurs more proximally, and involves the flexor sheath, as it generally does, sloughing of the tendons is to be apprehended, unless an immediate opening is made. And no slight superficial incision will suffice. The knife must be carried deep into the centre of the finger, so as to freely lay open the sheath containing the tendons. Early interference in cases of whitlow of the thumb and little finger is even more urgently required than in the case of the other three digits, because the digital mucous sheaths of the former are, as a rule, offshoots from the great common mucous sheath of the flexor tendons, and offer a ready means for the proximal extension of the inflammatory action. Every amputation of the fingers above the insertion of the tendons of the flexor profundus involves the opening of the flexor sheaths, and this, no doubt, explains the occasional occurrence of palmar trouble after operations of this kind. The open tubes offer a ready passage, by means of which septic material may travel proximally into the palm, and, in the case of the thumb and little finger, into the carpal tunnel and distal part of the forearm. DORSUM AND LATERAL BORDER OF THE FOREARM. The cutaneous nerves and vessels in this region have already been studied (p. 65). The parts which still require to be examined are : — 1. The deep fascia. 2. The supinator and extensor muscles. 3. The dorsal interosseous artery. 4. The perforating or terminal branch of the volar interosseous artery. 5. The dorsal interosseous nerve. Deep Fascia. — The deep fascia on the dorsal aspect of the forearm is stronger than that which clothes its volar surface. At the elbow it is firmly attached to the epicondyles of the humerus and the olecranon, and it receives a reinforcement of fibres from the tendon of the triceps muscle. There also it affords origin to the extensor muscles, and sends strong septa between them. At the wrist a thickened band — dorsal carpal ligament — is developed in connection with it. This can readily be distinguished from the thinner portions of the fascia, with which it is continuous proximally and distally, and it will be observed to stretch obliquely from the styloid process of the radius medially and distally across the wrist to the medial side of the carpus. Dissection. — The deep fascia should now be removed, but that portion of it near the elbow, which gives origin to the subjacent muscles, should be left in place. The dorsal carpal ligament should also be artificially separated and retained in situ. FOREARM AND HAND 133 Superficial Muscles. — The muscles in this region consist of a superficial and a deep group. The superficial muscles, as we proceed from the lateral to the medial border of the forearm, are: — (i) the brachio-radialis ; (2) the extensor carpi radialis longus ; (3) the extensor carpi radialis brevis; (4) the extensor digitorum communis ; (5) the extensor digiti quinti proprius; (6) the extensor carpi ulnaris; and (7) the anconaeus. This group therefore comprises one flexor of the elbow, three extensors of the wrist, two extensors of the fingers, and a feeble extensor of the forearm at the elbow- joint, viz. the anconaeus. In the lower part of the forearm the extensor digitorum communis is separated from the extensor carpi radialis brevis by a narrow interval, and in this appear two muscles belonging to the deep group. These turn round the lateral margin of the forearm, upon the surface of the radial extensors of the wrist, and end in tendons which go to the thumb. The proximal muscle is the abductor pollicis longus, and the distal muscle the extensor pollicis brevis. They are placed in close contact, and so intimately are their tendons connected that in many cases they appear at first sight to be blended together by their margins. Four of the superficial muscles arise by a common origin from the anterior part of the lateral epicondyle of the humerus, and at the same time derive fibres from the investing fascia and the septa it sends in between them. These are the extensor carpi radialis brevis, the extensor digitorum com- munis, the extensor digiti quinti proprius, and the extensor carpi ulnaris. The superficial muscles should be cleaned, and isolated as far as possible from each other. M. Brachio-radialis (O.T. Supinator Longus). — This muscle lies more on the volar than on the dorsal surface of the forearm. It takes origin in the arm from the proximal two-thirds of the lateral epicondylar ridge of the humerus and from the lateral intermuscular septum. Near the middle of the forearm a flat tendon emerges from its fleshy belly, and this proceeds distally to gain insertion into the lateral aspect of the expanded distal extremity of the radius at the base of the styloid process. The nerve of supply to this muscle comes from the radial nerve (musculo-spirat). M. Extensor Carpi Radialis Longus (O.T. Extensor Carpi Radialis Longior). — The long radial extensor of the carpus is placed dorsal to the brachio-radialis. It arises, from the 134 THE UPPER EXTREMITY distal third of the lateral epicondylar ridge of the humerus, and from the lateral intermiisciilar septum. From the fleshy portion of the muscle a long tendon proceeds, which passes under cover of the dorsal carpal ligament, and is inserted into the dorsal aspect of the base of the metacarpal bone of the index finger. This muscle is supplied by the radial nerve ( musculo- spiral). M. Extensor Carpi Radialis Brevis (O.T. Extensor Carpi Os triquetrum Os pisiform Os hamatum Extensor carpi ulnari Os lunatum Os capitatum Os naviculare manus Extensor carpi radialis brevis ,Os multangulum minus k/ Os multangulum majus Extensor carpi radialis longus • Abductor pollicis longus FIG. 52. — Dorsal aspect of the Bones of the Carpus and Metacarpus with Muscular Attachments mapped out. Radialis Brevior). — The extensor carpi radialis brevis is closely associated with the preceding muscle. It arises by the common extensor tendon from the lateral epicondyle of the humerus ; it also derives fibres from the radial collateral ligament of the elbow-joint, from the investing deep fascia, and the fibrous septa in connection with it. The tendon of the muscle accompanies that of the long radial extensor under cover of the dorsal carpal ligament, and is inserted into the dorsal aspect of the base of the third metacarpal bone immediately beyond the root of its styloid process. This muscle is supplied by the dorsal interosseous nerve. FOREARM AND HAND 135 M. Extensor Digitorum Communis. — The extensor digi- torum communis takes origin by the common tendon from the lateral epicondyle of the humerus. The deep fascia and the intermuscular septa in relation to it also contribute fibres. Its fleshy belly, in the lower part of the forearm, sends out four tendons, which pass under cover of the dorsal carpal ligament. On the dorsum of the hand they diverge and proceed onwards to the four fingers. Their arrangement and attachments on the dorsum of the hand and fingers will be afterwards considered (p. "145). This muscle is supplied by the dorsal interosseous nerve. M. Extensor Digit! Quinti Proprius (O.T. Extensor Minimi Digiti). — The extensor digiti quinti proprius is a slender fleshy belly which at first sight appears to be a part of the preceding muscle, but its tendon passes through a special compartment in the dorsal carpal ligament. It arises in common with the extensor digitorum communis, and is supplied by the dorsal interosseous nerve. M. Extensor Carpi Ulnaris. — The extensor carpi ulnaris arises, by means of the common extensor tendon, from the lateral epicondyle of the humerus, from the fascia of the forearm, and from the intermuscular septum between it and the extensor digiti quinti proprius. In the middle third of the forearm it receives some fibres from the strong fascial layer which binds it to the dorsal border of the ulna. The tendon does not become free from the fleshy fibres until it approaches close to the wrist. It occupies the groove on the dorsal aspect of the distal end of the ulna, between the head and styloid process, and passing under cover of the dorsal carpal ligament is inserted into the tubercle on the base of the metacarpal bone of the little finger. This muscle is supplied by the dorsal interosseous nerve. M. Anconseus (Anconeus). — The anconaeus is a short triangular muscle placed on the dorsal aspect of the elbow-joint. It presents a narrow origin from the posterior aspect of the lateral epicondyle of the humerus. From this its fibres spread — the upper fibres passing transversely medially, whilst the others proceed medially and distally with an increasing degree of obliquity towards its distal end. It is inserted into the lateral surface of the olecranon, and into the proximal third of the dorsal surface of the body of the ulna. 136 THE UPPER EXTREMITY The anconaeus is frequently more or less directly continuous with the triceps, and this, together with the fact that it gets a special branch of supply from the radial nerve, has led some anatomists to regard it as a piece of the triceps muscle. This is not the case, however ; it belongs to, and is therefore properly classified with, the group of muscles on the extensor aspect of the forearm. The nerve of supply to the anconaeus has already been dissected. It is a long slender branch from the radial nerve (musculo-spiral), which descends to its destination in the substance of the medial head of the triceps. In addition to this, the distal part of the muscle usually receives a twig from the dorsal interosseous nerve. Dissection. — Reflect the extensor digitorum communis and the extensor digiti quinti proprius. Divide the fleshy belly of each about its middle, and throw them proximally and distally. In doing this care must be taken to secure and preserve the nerve twigs from the dorsal interosseous nerve which enter these muscles on their deep surface. The dorsal interosseous artery and nerve, together with the deep muscles, are now exposed, and may be fully dissected. In the distal part of the forearm the terminal part of the dorsal interosseous nerve dips under cover of the extensor pollicis longus, to reach the interosseous membrane and the back of the carpus. In following this part of the nerve, the terminal or perforating branch of the volar interosseous artery will be seen appearing on the dorsum of the forearm, under cover of the extensor pollicis longus. Deep Muscles. — These are — (i) the supinator ; (2) the abductor pollicis longus; (3) the extensor pollicis brevis; (4) the extensor pollicis longus ; and (5) the extensor indicis proprius. The supinator will be recognised from the close manner in which it is applied to the proximal part of the body of the radius. The other muscles take origin proximo-distally in the order in which they have been named. The attach- ments of the supinator cannot be satisfactorily studied at present. They will be described at a later stage of the dissection. M. Abductor Pollicis Longus (O.T. Extensor Ossis Metacarpi Pollicis). — This muscle arises from both bones of the forearm, and from the interosseous membrane which stretches between them. Its origin from the radius corre- sponds to the middle third of its dorsal surface ; its origin from the ulna is more proximal, from the lateral part of the dorsal surface of the body immediately distal to the oblique line which marks the distal limit of the insertion of the anconaeus. The muscle proceeds distally and laterally, and comes to the surface in the interval between the extensor digitorum com- FOREARM AND HAND 137 Closely accom- . triceps •*•""-• M. biceps brachii M. supinator. munis and the extensor carpi radialis brevis. panied by the ex- tensor pollicis brevis it crosses the two radial extensors. The tendon which issues from it at this point is con- tinued distally over the lateral side of the ex- panded lower end of the radius, and under cover of the dorsal carpal ligament. It is inserted into the lateral side of the base of the metacarpal bone of the thumb. This muscle is supplied by the dorsal interosseous nerve. M. Extensor Pollicis Brevis (O.T. Extensor Primi Internodii Pollicis). — This muscle is placed along the distal border of the pre- ceding muscle. It arises from a small portion of the dorsal surface of the radius, and also from the in- terosseous mem- brane. Its tendon is closely applied to that of the abductor Ext. carp, uln. Ext. dig. comm. and ext. indici id. exts. \bd. poll. long, ind ext. poll, jrev. Ext. poll. long. FIG. 53. — Dorsal aspect of Bones of Forearm with Attachments of Muscles mapped out. 138 THE UPPER EXTREMITY pollicis longus, and accompanies it beneath the dorsal carpal ligament. It may be traced on the dorsal aspect of the metacarpal bone of the thumb to the base of the proximal phalanx, into which it is inserted. This muscle is supplied by the dorsal interosseous nerve. M. Extensor Pollicis Longus (O.T. Extensor Secundi Inter- nodii Pollicis). — The extensor pollicis longus takes origin from the lateral part of the dorsal surface of the body of the ulna in its middle third, and also from the interosseous membrane. It, to some extent, overlaps the preceding muscle, and it ends in a tendon which passes under cpver of the dorsal carpal ligament, where it occupies a deep narrow groove on the dorsum of the distal end of the radius. On the carpus it takes an oblique course, and, crossing the tendons of the two radial extensors and the radial artery, reaches the thumb. It is inserted into the base of the distal phalanx of that digit. The extensor pollicis longus is supplied by the dorsal interosseous nerve. When the thumb is powerfully extended in the living person the tendons of its three last - mentioned muscles become prominent on the lateral aspect of the wrist. The oblique course of the tendon of the extensor pollicis longus is rendered evident, and a distinct depression between it and the other two tendons is seen. M. Extensor Indicis Proprius (O.T. Extensor Indicis).— The extensor indicis proprius arises below the preceding muscle from a limited area on the dorsal surface of the ulna and from the interosseous membrane. Its tendon accom- panies those of the extensor communis under cover of the dorsal carpal ligament, and will afterwards be traced to its insertion on the index finger. This muscle is supplied by the dorsal interosseous nerve. Arteria Interossea Dorsalis (O.T. Posterior Interosseous Artery). — This vessel arises in the volar part of the forearm, from the common interosseous branch of the ulnar artery. It at once proceeds dorsally between the two bones of the forearm, in the interval between the proxi- mal border of the interosseous membrane and the oblique cord. In the present dissection it makes its appearance between the contiguous borders of the supinator and the abductor pollicis longus, and then it extends distally between the superficial and deep muscles on the back of the forearm. It gives branches to these, and by the time it has reached the FOREARM AND HAND M. triceps Orb. lig.- N. inteross. dorsal M. anconaeus - A. inteross. recurr. M. pronator teres" Nerve to ext. pollicis - longus and ext. indicis N. inteross. dorsalis M. ext. indicis M. ext. dig. quinti ^ M. ext. dig. comm. __ A. carpea dorsalis,... A. radialis ^ *" M. biceps brachii M. brachialis * M. abd. poll. long. M. ext. poll. brev. FIG. 54. — Dissection of the Dorsum of the Forearm and Hand. 140 THE UPPER EXTREMITY distal end of the forearm it is greatly reduced in size. In a well-injected limb it will be seen to end on the dorsum of the carpus by anastomosing with the volar interosseous artery and the dorsal carpal arteries. In addition to the branches which it supplies to the muscles, it gives off one large branch called the interosseous recurrent artery. The arteria interossea recurrens takes origin from the parent trunk as it appears between the supin- ator and the abductor pollicis longus, and turns proximally, under cover of the ancongeus muscle, to reach the dorsal aspect of the lateral epicondyle of the humerus. The ancon- seus should be detached from its origin and thrown medially, in order that the artery may be traced to its termination. The inter- osseous recurrent artery will then be seen to end by anastomosing with the posterior terminal branch of the profunda artery of the armr Anastomosis around A. brachialis A. profunda ""brachii (O.T. superior profunda) A. collaterals ulnaris superior (O.T. inferior profunda) A. collateralis ___. ulnaris inferior (O.T. anasto- matic) Ant. terminal branch of A. prc funda brachii -.A. radialis __.,A. ulnaris T ...^Aa. recurrentes 'tilnares _(A. interossea recurrens •.A. interossea dorsalis "A. interossea volaris the Elbow - joint. — The series of inosculations around the elbow should now be reviewed as a whole. A distinct inos- FIG. 55. — Diagram of Anastomosis around the Elbow-joint. culation will be found to take place upon both the anterior and posterior aspect of each epicondyle of the humerus. Behind the lateral epicondyle the interosseous recurrent artery joins the posterior branch of the profunda brachii artery : anterior to the same epicondyle the anterior branch of the profunda brachii artery communicates FOREARM AND HAND 141 with the radial recurrent. On the medial side of the joint the anterior and posterior ulnar recurrent arteries ascend respectively in front of and behind the medial epicondyle, the former anastomoses with the anterior branch of the inferior ulnar collateral artery, and the latter with the posterior branch of the same artery and with the superior ulnar collateral artery. In this sketch of the anastomosis around the elbow-joint only the leading inosculations are mentioned. Rich networks of fine vessels are formed over the olecranon and the two epicondyles of the humerus. One very distinct and tolerably constant arch requires special mention. It is formed by a branch which crosses the posterior aspect of the humerus, immediately above the olecranon fossa, and connects the posterior branch of the profunda brachii artery with the posterior branch of the inferior ulnar collateral artery. Nervus Interosseus Dorsalis (O.T. Posterior Interosseous Nerve). — This is the continuation of the profunda terminal branch of the radial (musculo-spiral) nerve. It reaches the dorsum of the forearm by traversing the substance of the supinator, and at the same time winding round the lateral aspect of the body of the radius. It emerges from the supina- tor a short distance proximal to the distal border of the muscle, and is carried distally between the superficial and deep muscles on the back of the forearm. Reaching the proximal border of the extensor pollicis longus, it leaves the dorsal interosseous artery, dips anterior to the extensor pollicis longus, and -joins the volar interosseous artery on the dorsal aspect of the inter- osseous membrane. It will afterwards be traced to the dorsum of the carpus, where it ends, under cover of the- tendons of the extensor digitorum communis, in a gangliform enlargement. The branches which spring from the dorsal interosseous nerve in the forearm are given entirely to muscles. Before the profunda branch pierces the supinator and becomes the dorsal interosseous nerve, it gives branches both to it and to the extensor carpi radialis brevis. After it appears on the dorsum of the forearm as the dorsal interosseous nerve it supplies the extensor digitorum communis, the extensor digiti quinti pro- prius, the extensor carpi ulnaris, the abductor pollicis longus, two extensors of the thumb, and the extensor indicis proprius. It therefore supplies all the muscles on the lateral and dorsal aspects of the forearm, with the exception of the brachio-radialis and the extensor carpi radialis longus, which derive their nerve- 142 THE UPPER EXTREMITY supply directly from the radial nerve (O.T. musculo-spiral). The anconaeus also derives its main nerve of supply from the radial, but it also frequently obtains a second twig from the dorsal interosseous nerve. Terminal Branch of the Arteria Inter ossea Volaris.— The terminal or perforating branch of the volar inter- osseous artery is a vessel of some size. It appears through the interosseous membrane, about two inches or so proximal to the distal end of the forearm. Accompanied by the dorsal interosseous nerve it runs distally under cover of the extensor pollicis longus, and ends on the dorsum of the carpus by anastomosing with the dorsal carpal arch and the dorsal interosseous artery. DORSAL ASPECT OF THE WRIST AND HAND. Upon the dorsal aspect of the wrist and hand the following structures have still to be examined : — 1. The radial artery and its branches. 2. The dorsal carpal ligament. 3. The extensor tendons of the fingers. Radial Artery. — It is only a small portion of the radial artery that is seen in this dissection. At the distal end of the radius the vessel turns dorsally below the styloid process and upon the radial collateral ligament of the radio-carpal joint. Having gained the dorsal aspect of the carpus, it runs distally upon the navicular and os mult- angulum majus, and finally disappears from view by turning volarwards through the proximal part of the first interosseous space, and between the heads of origin of the first dorsal interosseous muscle (Fig. 54, p. 139). In the palm it takes the chief share in the formation of the deep volar arch. While the radial artery rests on the radial collateral carpal ligament, it is deeply placed, and is crossed by the tendons of the abductor pollicis longus and the extensor pollicis brevis. On the carpus it lies nearer the surface, and is crossed obliquely by the extensor pollicis longus. It is accompanied by two venae, comites and some fine filaments from the lateral cutaneous nerve of the forearm which twine around it. FOREARM AND HAND 143 The branches which spring from the radial artery in this part of its course are of small size. They are : — 1. The dorsal carpal. 2. The dorsal metacarpal. 3. The two dorsales pollicis arteries. 4. The dorsalis indicis artery. The dorsal radial carpal artery takes origin on the lateral aspect of the wrist, and runs medially upon the carpus to join the corresponding carpal branch of the ulnar artery. The arch thus formed is placed under cover of the extensor tendons, and gives off two branches which run distally in the third and fourth inter -metacarpal intervals. They are termed the second and third dorsal metacarpal arteries. The first dorsal metacarpal artery arises, as a rule, from the radial trunk, although not infrequently it may be seen to spring from the dorsal carpal arch. It extends distally in the second interosseous space. The three dorsal metacarpal arteries are brought into connection with the arteries in the palm by communicating branches. They are joined by the three perforating twigs of the arcus volaris profundus. These make their appearance on the dorsum between the heads of the three medial dorsal inter- osseous muscles. Further, at the distal ends of the interosseous spaces the dorsal metacarpal arteries usually send rami per- forantes inferiores to join the corresponding common volar digital arteries in the palm. The two dorsal arteries of the thumb run distally upon either side of that digit. The dorsal artery of the index is distributed on the lateral side of the index. Dorsal Carpal Ligament. — This has been seen to be an aponeurotic band which stretches obliquely across the wrist. It is merely a thickened portion of the deep fascia, and its attachments are so arranged that it does not interfere with the free movement of the radius and hand during pronation and supination. On the lateral side it is fixed to the lateral margin of the distal end of the radius, whilst on the medial side it is attached to the os triquetrum and os pisiforme, and also to the palmar aponeurosis. In the case of the transverse carpal liga- ment one large compartment, or tunnel, is formed for the flexor tendons ; not so in the case of the dorsal carpal ligament. Partitions or processes proceed from its deep surface, and 144 THE UPPER EXTREMITY these are attached to the ridges on the dorsal aspect of the distal end of the radius, so as to form a series of six bridges Extensor pollici longus Extensor carp radialis brevi: Extensor carpi radialis Ion Extensor digitorum communis Extensor indicis proprius ~ tensor digiti nti proprius Extensor carpi ulnaris Extensor pollicis brevis Abductor pollicis longus' Radial artery Flexor pollicis Flexor carpi Radial is Median nerve Palmaris longus Flexor digitorum profundus ar artery and nerve Flexor~digitorum'Flexor carPi ulnaris sublimis FIG. 56. — rTransverse section through Forearm immediately proximal to the Wrist -joint to show the arrangement of the Tendons. or compartments for the tendons. Each of these is lined by a special mucous sheath, to facilitate the play of the tendons within it. The different compartments may now be success- FIG. 57.— (From Luschka. ) 1. Middle metacarpal bone. 2. Tendon of flexor sublitnis. 3. Tendon of flexor profundus. 4. Second lumbrical muscle. 5. Second dorsal interosseous muscle. 6. Extensor tendon. I., II., and III. The three phalanges. ively opened up so that the arrangement of the tendons with reference to the dorsal carpal ligament may be studied. The first compartment is placed on the lateral side of the base of the styloid process of the radius, and corresponds with the broad oblique groove which is present in this part of the FOREARM AND HAND 145 bone. It contains two tendons, viz. the tendons of the abductor pollicis longus and the extensor pollicis brevis. The second compartment corresponds with the most lateral groove on the dorsal aspect of the radius. It is broad and shallow, and it holds the tendons of the extensor carpi radialis longus, and extensor carpi radialis brevis. The third compartment is formed over the narrow, deep, oblique intermediate groove on the dorsum of the distal end of the radius, and through it the tendon of the extensor pollicis longus passes. The fourth compartment is placed over the wide shallow groove which marks the medial part of the dorsal aspect of the distal end of the radius. It is traversed by five tendons, viz. the four tendons of the extensor digitorum communis and the tendon of the extensor indicis proprius. The fifth compartment is situated over the interval between the distal ends of the radius and ulna. It contains the slender tendon of the extensor digiti quinti proprius. The sixth and most medial compartment, which corresponds with the groove on the dorsum of the distal end of the ulna, encloses the tendon of the extensor carpi ulnaris. Extensor Tendons of the Fingers. — The four tendons of the extensor digitorum communis, when they emerge from their compartment under the dorsal carpal ligament diverge on the dorsum of the hand to reach the four fingers. The tendon of the ring finger will be seen to be connected by a tendinous slip with the tendon on either side of it. This explains the small degree of independent movement in a backward direction which the ring finger possesses. The arrangement of the tendons on the fingers is the same in each case. Upon the dorsal aspect of the first phalanx the tendon expands so as to cover it completely. Into the margins of this "dorsal expansion " the delicate tendons of the lumbrical and inter- osseous muscles are inserted. Near the first interphalangeal joint the expansion becomes marked off into three portions — a central and two lateral. The central part, which is the weakest, is inserted into the dorsal aspect of the base of the second phalanx. The stronger lateral portions unite into one piece beyond this, and gain an insertion into the base of the ungual phalanx. The tendon of the extensor indicis proprius joins the expan- sion of the extensor tendon on the dorsal aspect of the first phalanx of the index finger. VOL. i — 10 146 THE UPPER EXTREMITY The tendon of the extensor digiti quinti proprius splits into two parts. Of these the lateral joins the tendon of the common extensor which goes to that digit, whilst the medial ends in the dorsal expansion. Nervus Interosseous Dorsalis (O.T. Posterior Interosseous Nerve). — The terminal filament of this nerve can now be traced distally to the dorsal aspect of the carpus. It passes under cover of the extensor indicis proprius, the tendons of the extensor communis, and the dorsal carpal ligament. On the carpus it ends in a gangliform swelling, from which fine twigs proceed for the supply of the numerous joints in the vicinity. Dissection. — The limb should now be turned round, so that the trans- verse metacarpal ligament which stretches across the volar surface of the heads of the metacarpal bones may be examined previous to the dissection of the interosseous muscles. Transverse Metacarpal Ligament. — The transverse liga- ment of the head of the metacarpal bones is a strong band composed of transverse fibres, which is placed upon the volar aspect of the heads of the four metacarpal bones of the fingers. Commencing on the lateral side upon the distal extremity of the index metacarpal, it ends at the medial margin of the hand upon the head of the metacarpal bone of the little finger. It is not directly attached to the bones, but is fixed to the powerful accessory volar ligaments of the four medial metacarpo- phalangeal joints, and it effectually prevents excessive separation of the metacarpal bones from each other. Dissection. — To obtain a satisfactory view of the interosseous muscles the transverse part of the adductor pollicis, if not previously reflected, should be detached from its origin, and thrown laterally towards its insertion into the thumb. The transverse metacarpal ligament must also be divided in the intervals between the fingers. Mm. Interossei. — The interosseous muscles occupy the intervals between the metacarpal bones. They are seven in number, and are arranged in two groups, viz. a dorsal and a volar. The mm. interossei dorsales are four in number, and are more powerful than the volar muscles. They are best seen on the dorsal aspect of the hand, but they are also visible in the palm. They act as abductors of the fingers from the central line of the middle digit, and their in- sertions are arranged in accordance with this action. Each FOREARM AND HAND 147 muscle arises by two heads from the contiguous surfaces of the two metacarpal bones between which it lies, and the fibres converge in a pennate manner upon a delicate tendon. In the case of the first or most lateral dorsal interosseous muscle^ this tendon is inserted into the lateral side of the base of the first phalanx, and also into the lateral margin of the dorsal expansion of the extensor tendon of the index. The second and third dorsal interosseous muscles are inserted in a similar manner upon either side of the base of the first phalanx of the middle finger ; whilst \hefourth has a corresponding insertion upon the medial aspect of the base of the first phalanx of the ring finger. The first dorsal interosseous muscle is frequently termed the abductor indicis, and between its two heads of origin the radial artery enters the palm. Between the heads of the other three muscles the small perforating arteries pass. The three mm. interossei volares can only be seen on the palmar aspect of the hand. They act as adductors of the index, ring, and little fingers towards the middle digit, and each muscle is placed upon the metacarpal bone of the finger upon which it acts. The first volar interosseous muscle there- fore arises from the metacarpal bone of the index finger, and its delicate tendon is inserted upon the medial side of that digit, partly into the base of the first phalanx, and partly into the extensor expansion. The second palmar interosseous muscle springs from the metacarpal bone of the ring finger, and has a similar insertion into the lateral side of that digit. The third palmar interosseous muscle takes origin from the metacarpal bone, and presents a corresponding insertion into the lateral side of the first phalanx and extensor expansion of the little finger. The interosseous muscles are supplied by the profunda branch of the ulnar nerve. Deep Head of M. Flexor Pollicis Brevis. — This small muscle, which is also known as the m. interosseous primus volaris (Henle), can best be displayed from the dorsal aspect of the hand by reflecting the lateral head of the first dorsal interosseous muscle. It arises from the base of the metacarpal bone of the thumb, and is inserted into the medial sesamoid bone of that digit. It is deeply placed, and is entirely covered, on its volar aspect, by the oblique part of the adductor pollicis. Tendon of the Flexor Carpi Radialis. — The tendon of this muscle should now be traced through the groove on the volar aspect of the os multangulum majus to its insertion into the base of the metacarpal bone of the index. It presents also a minor attachment to the base of the middle metacarpal bone. 148 THE UPPER EXTREMITY Dissection. — All the muscles around the elbow-joint should be removed. In raising the brachialis and the triceps from the anterior and dorsal aspects of the articulation, some care is required to avoid injury to the anterior and posterior parts of the capsule. It is advisable to remove the supinator last, because it is only when this muscle is completely isolated that a proper idea of its attachments and mode of action can be obtained. M. Supinator (O.T. Supinator Brevis). — The supinator envelops the proximal part of the body and the neck of the radius, covering it completely, except on its medial side (Figs. 41, 54, pp. ioo, 139). It arises from the deep de- pression distal to the incisura radialis of the ulna, and also from the radial collateral ligament of the elbow and the annular ligament of the radius. From this origin the fibres sweep round the dorsal, lateral, and volar surfaces of the radius, and clothe its body as far distally as the insertion of the pronator teres. The dorsal interosseous nerve traverses the substance of the muscle, and separates it into two layers. ARTICULATIONS. ARTICULATIO CUBITI (ELBOW-JOINT). This joint includes (i) the articulatio humero-ulnaris, (2) the articulatio humero-radialis, and (3) the articulatio radio- ulnaris proximalis. In the humero-ulnar articulation the trochlea of the humerus is grasped by the incisura semi- lunaris of the ulna. In the radio-humeral articulation the capitellum of the humerus rests in the shallow fovea capituli of the radius, and in the proximal radio-ulnar articulation the circumferentia articularis of the head of the radius is held in apposition with the incisura radialis of the ulna by the lig. annulare. The joint is surrounded by a capsule which is reinforced at the sides by collateral ligaments ; in addition the interosseous membrane, which passes between the interosseal crests of the radius and ulna, and the oblique cord, which connects the tuberosity of the ulna with the proximal part of the inter- osseous crest of the radius, help to keep the radius and ulna in apposition and are therefore included in the ligaments of the elbow-joint. The ligaments of the elbow-joint are therefore— 1. Capsula articularis. 2. Lig. collaterale ulnare. 3. Lig. collaterale radiale. 4. Lig. annulare radii. 5. Membrana interossea antibrachii. 6. Chorda obliqua. ARTICULATIONS 149 Biceps brachii Brachial The articular capsule is attached proximally to the antero- medial and antero-lateral surfaces of the humerus, above the coronoid and radial fossae respectively. At the sides it is attached to the epicondyles and posteriorly to the posterior sur- face on which the line of attachment passes through the upper part of the fossa olecrani. Distally the capsule is attached to the anterior margin of the proximal, medial, and lateral surfaces of the olecranon ; to the medial and volar margins of the coronoid process of the ulna, and to the annular ligament of the radius. The anterior part of the capsule consists of fibres which take an irregular course over the an- terior aspect of the joint. The posterior part of the capsule is weaker than the an- terior and its attach- ment to the posterior surface of the humerus is comparatively loose. Ligamentum Col- lateraleRadiale(O.T. External Lateral Ligament). — This is a strong but short ligamentous band which is attached above to the distal aspect of the lateral epicondyle of the humerus. Below, it is fixed to the annular ligament of the radius, and also, more posteriorly, to the lateral side of the olecranon of the ulna. The annular ligament is a strong ligamentous collar which surrounds the head of the radius, and retains it in the incisura radialis of the ulna. Ligamentum Collaterale Ulnare (O.T. Internal Lateral Ligament). — The ulnar collateral ligament, taken as a whole, is fan-shaped. By its proximal pointed part it is attached to the medial epicondyle of the humerus. Distally it spreads out to find insertion into the coronoid process and olecranon. It consists of three very distinct portions, viz. an anterior, a posterior, and a transverse. The anterior part springs from the distal and anterior part of the medial epicondyle, and is attached to the medial margin of the coronoid process of the ulna. The posterior part is Flexor carpi ulnaris FIG. 58. — Vertical section through Humerus and Ulna at the Elbow-joint. THE UPPER EXTREMITY attached above to the distal and dorsal part of the medial epi- condyle, whilst distally it is fixed to the medial border of the olecranon. The transverse part consists of a band of fibres, which bridges across the notch between the olecranon and coronoid process, to both of which it is attached. The lig. annulare and the chorda obliqua will be described later (see pp. 155-157). Stratum Synoviale (Synovial Membrane). — The joint should be opened by making a transverse incision through the Interosseous Coronoid membrane Radius process Medial epi- condyle Anterior part of ulnar collateral ligament Posterior part of ulnar collateral ligament Olecranon Transverse part of ulnar collateral ligament FIG. 59. — Medial aspect of Elbow-joint. anterior part of the capsule. The stratum synoviale will be seen lining the deep surface of the capsule, from which it is reflected upon the non-articular parts of the bones which are enclosed within the capsule. Anterior to the humerus it lines the radial and coronoid fossae, and posteriorly it is prolonged proximally in the form of a loose diverticulum into the oiecranon fossa. In these fossae a quantity of soft oily fat is developed between the bone and the stratum synoviale. In this way pliable pads are formed which occupy the recesses when the bony processes are withdrawn from them. Distally the synovial membrane of the elbow-joint is ARTICULATIONS 1 5 1 prolonged into the proximal radio-ulnar joint, so that both articulations possess a single continuous synovial cavity. Movements at the Elbow-joint. — The movements at the elbow -joint must not be confounded with those that take place at the proximal radio- ulnar joint. At the elbow-joint two movements, viz. Jlexion, or forward movement of the forearm, and extension, or backward movement of the forearm, are permitted. The imiscles which are chiefly concerned in flexing the forearm upon the Humerus Anterior ligament ' Lig. collaterale radiale Lig. annulare Radius Epicondylus medialis Lig. collaterale ulnare Tendon of biceps brachii Chorda obliqua Ulna FIG. 60. — Anterior aspect of the Elbow-joint. arm at the elbow-joint are the biceps, the brachialis, the muscles attached to the medial epicondyle, and the brachio-radialis. The muscles which extend the forearm at this articulation are the triceps and anconaeus and the muscles which spring from the lateral epicondyle. Dissection. — It is advisable to study the radio -carpal, or wrist -joint, before the articulations between the two bones of the forearm are examined. The transverse volar and dorsal carpal ligaments, together with the extensor and flexor tendons, should be completely removed from the wrist. No attempt, however, should be made to detach the extensor tendons from the dorsal aspects of the fingers and thumb. The short muscles of the thenar and hypothenar eminences must also be taken away. 152 THE UPPER EXTREMITY ARTICULATIO RADIO-CARPEA (WRIST-JOINT). The radio-carpal or wrist-joint is the joint between the forearm and the hand. The proximal face of the joint is formed by the distal articular surface of the radius and the discus articularis, and the distal surface by the navicular, lunate, and triquetral bones, and the interosseous ligaments which connect them together. The opposed surfaces are retained in apposition by a capsular ligament in which at least four thickened bands can be recognised, they are :— Lig. radiocarpeum volare. 3. Lig. collaterale radiale 2. Lig. radiocarpeum dorsale. 4. Lig. collaterale ulnare. The capsule is attached proximally to the borders of the distal ends of the radius and the ulna, and to the borders of the discus articularis. Distally it is connected with the bones of the proximal row of the carpus, with the exception of the pisiform, and some of its fibres can be traced to the os capitatum. The volar radio-carpal ligament springs from the anterior border of the styloid process of the radius and the adjacent part of the anterior border of the distal end of the radius. Distally it breaks up into flat bands which are attached to the navicular, lunate, and capitate bones. In many cases a volar ulnar-carpal ligament is also found. When present it extends from the anterior aspect of the base of the styloid process and the adjacent anterior part of the head of the ulna to the triquetral, pisiform, and capitate bones. The dorsal radio-carpal band springs from the posterior border of the distal end of the radius, and is attached distally to all the bones of the proximal row of the carpus, except the pisiform. Its fibres are often separable into a number of distinct bands. The radial collateral carpal ligament passes from the tip of the styloid process of the radius to the lateral part of the navicular, and the ulnar collateral carpal ligament connects the styloid process of the ulna with the triquetral bone. Articular Surfaces. — Divide the anterior and lateral parts of the capsule by a transverse incision carried across the front of the articulation. The hand can now be bent backwards, so as to expose fully the articular surfaces opposed to each other in this joint. The carpal surface is composed of the proximal articular ARTICULATIONS 153 facets of the os naviculare and os lunatum, and a very small articular facet on the extreme lateral part of the proximal surface of the os triquetrum. Two interosseous ligaments stretch across the narrow intervals between these bones — one on either side of the os lunatum — and complete the carpal surface. Formed of these factors the carpal surface is convex in all directions. Further, it should be observed that the articular surface extends distally to a greater extent dorsally than on the volar aspect. The proximal surface or socket (Fig. 61) is elongated from side to side, and concave in all directions. The greater part of it is formed by the distal end of the radius, but to the medial side of this by the discus articularis of the distal radio- Head of ulna Styloid process , of ulna Surface for os,. naviculare man us m*-^-. .< - // fj. Apex of discus ^ , articularis Groove for tendon of ext. pollicis longus FIG. 61. — 1Carpal Articular Surfaces of the Radius and of the Discus Articularis of the Wrist. ulnar joint likewise enters into its construction. The distal articular surface of the radius is divided by a low ridge into a lateral triangular and a medial quadrilateral facet. The lateral facet, in the ordinary position of the hand, is in contact with the greater extent of the proximal articular surface of the os naviculare. The medial facet of the radius, together with the discus articularis, forms a much larger surface, triangular in outline, which is opposed to the proximal articular surface of the os lunatum. When the hand is placed in line with the forearm no part of the proximal articular surface is allotted to the os triquetrum : its small articular facet rests against the medial part of the capsule of the joint. When the hand is moved medially (i.e. adducted), however, the os triquetrum travels laterally, and its articular surface comes into contact with the distal 154 THE UPPER EXTREMITY surface of the discus articularis. The os lunatum at the same time crosses the bounding ridge on the distal surface of the radius, and encroaches on the territory of the os naviculare, whilst a considerable part of the surface of the os naviculare leaves the radius and comes into contact with the lateral part of the capsule. Synovial Membrane. — The synovial membrane of the radio-carpal joint lines the capsule and it covers the proximal surfaces of the two interosseous ligaments which complete the carpal surface. Sometimes the discus articularis is imperfect, and in these cases the synovial membrane of the radio -carpal joint becomes continuous with the synovial membrane of the inferior radio-ulnar joint. Movements at the Radio-carpal Joint. — The hand can be moved in four directions at the radio -carpal joint. Thus we have — (a) volar movement, or flexion ; (b] dorsal movement, or extension ; (c] ulnar movement, or adduction ; (d) radial movement, or abduction. In estimating the extent of these movements in the living person the student is apt to be misled by the increase of range which is contributed by the carpal joints. Thus, flexion is in reality more limited than extension, although by the combined action of both carpal and radio-carpal joints the hand can be carried much more freely volarwards than dorsally. Adduction, or ulnar flexion, can be produced to a greater extent than abduction, or radial flexion. In both cases the extent of movement at the radio-carpal joint proper is very slight, but the range is extended by movements of the carpal bones. The styloid process of the radius interferes with abduction. The muscles which are chiefly concerned in producing these different movements of the hand at this joint are the following : — (a) flexors — the flexor carpi radialis, the palmaris longus, and the flexor carpi ulnaris ; (ti) extensors — extensor carpi radialis longus, the extensor carpi radialis brevis, and the extensor carpi ulnaris ; (c) abductors, or radial flexors — flexor carpi radialis, extensor carpi radialis longus, abductor pollicis longus, and the extensor pollicis brevis; (d) adductors, or ulnar flexors — extensor carpi ulnaris and flexor carpi ulnaris. ARTICULATIONES RADIO-ULNARES (RADIO-ULNAR JOINTS). At the two radio-ulnar joints, proximal and distal, the movements of pronation and supination take place. At the proximal joint the medial part of the head of the radius fits into the incisura radialis of the ulna ; at the distal the small capitulum ulnae is received into the incisura ulnaris on the medial side of the distal end of the radius. In connection with these joints there are special ligaments which retain the bones in apposition. These are — (i) for the proximal radio-ulnar joint, the annular ligament ; and ARTICULATIONS 155 (2) for the distal radio-ulnar joint, (a) a capsule, and (b} the discus articularis. In addition there are other ligaments which pass between the bodies of the two bones of the forearm, and are therefore common to the two articulations, viz. the oblique cord and the interosseous membrane. To expose these ligaments the volar and dorsal muscles of the forearm must be completely removed. Ligamentum Annulare Radii (O.T. Orbicular Ligament). —This is a strong ligamentous collar which encircles the Olecranon Incisura radiahs . Transverse portion ^ of lig. collaterale ulnare Incisura semilunaris Lig. annulare Processus coronoideus FIG. 62. — Annular Ligament of the Radius. capitulum radii and retains it in the incisura radialis of the ulna. It forms four-fifths of a circle, and is attached by its extremities to the volar and dorsal margins of the incisura radialis. It is somewhat narrower distally than proximally, so that, under ordinary circumstances, the head of the radius cannot be withdrawn from it in a distal direction, and it is braced tightly upwards towards the elbow, and greatly strengthened by the anterior and posterior portions of the capsule of the elbow-joint, and by the radial collateral liga- ment which are incorporated with it along its proximal border. Its distal border is loosely attached to the neck of the radius by a prolongation of the stratum synoviale, which is covered externally by a thin layer of fibrous tissue. The Capsule of the Inferior Radio-ulnar Joint. — This 156 THE UPPER EXTREMITY capsule consists of lax fibres which can have little influence in retaining the distal extremities of the bones in apposition. The capsule is attached to the anterior and posterior surfaces of both bones of the forearm, to the lower parts of the inter- osseous crests and to the anterior and posterior borders of the discus articularis. A diverticulum of the capsule which is prolonged from the joint area for some distance proximally, between the bones of the forearm, is called the recessus sacciformis. Discus Articularis (O.T. Triangular Fibro-Cartilage).— The discus articularis is the true bond of union at the inferior radio-ulnar joint. It has already been noticed in connection with the radio-carpal joint, where it extends the radial articular surface in a medial direction, and is interposed between the lower end of the ulna and the os lunatum. It is a thick, firm plate, attached by its base to the distal margin of the incisura ulnaris of the radius. The apex of the cartilage is directed medially, and is fixed to the depression on the distal end of the ulna at the root of the styloid process. It intervenes between the inferior radio-ulnar joint and the radio-carpal joint. Stratum Synoviale (Synovial Membrane). — The synovial membrane of the proximal radio-ulnar joint is continuous with that of the elbow-joint. It is prolonged distally so as to line the lig. annulare, and it protrudes beyond this for a short distance upon the neck of the radius. The cavity of the inferior radio-ulnar joint and the synovial membrane are prolonged between the head of the ulna and the discus articularis. Sometimes the discus articularis is perforated ; when this is the case, the inferior radio-ulnar joint-cavity communicates with the cavity of the radio-carpal joint. Membrana Interossea Antibrachii (O.T. Interosseous Mem- brane).— This is a fibrous membrane which stretches across the interval between the two bones of the forearm, and is attached to the crista interossea of each. Its proximal border is situated about an inch distal to the tubercle of the radius. Distally it blends with the capsule of the inferior radio-ulnar joint. The fibres which compose it run for the most part obliquely distally and medially from the radius to the ulna, although several slips may be noticed taking an opposite direction. The dorsal interosseous vessels pass dorsally, ARTICULATIONS 157 above its proximal margin, between the two bones of the forearm, whilst the terminal branch of the volar interosseous artery pierces it about two inches above its distal end. This ligament braces the two bones together in such a manner that forces, passing proximally through the radius, are trans- mitted from the radius to the ulna, and it extends the surface of origin for the muscles of the forearm. By its volar surface it gives origin to the flexor digitorum profundus and the flexor pollicis longus muscles, whilst from its dorsal surface springs fibres of the two extensor muscles of the thumb, the abductor pollicis longus, and the extensor indicis proprius. Chorda Obliqua (O.T. Oblique Ligament). — This is a weak band of fibres which springs from the tuberosity of the ulna, and extends obliquely distally and laterally to find an attach- ment to the radius immediately distal to its tuberosity. It crosses the open space between the bones of the forearm above the proximal border of the interosseous membrane. The chorda obliqua is often absent, and unless the utmost care be taken in removing the adjacent muscles it is apt to be injured. Movements at the Radio-ulnar Joints. — At these articulations the movements of pronation and supination take place. When the limb is in a condition of complete supination the palm of the hand is directed anteriorly, the thumb laterally, and the two bones of the forearm are parallel, the radius lying along the lateral side of the ulna. In the movement of pronation the radius is thrown across the ulna, so that its distal end comes to lie across the volar surface and on the medial side of the ulna. Further, the hand follows the radius in this movement, and the dorsal aspects of both are directed forwards, and the thumb is turned medially. The dissector should analyse, as far as possible in the part upon which he is engaged, the movements at the two radio-ulnar joints which produce these effects. At the same time it should be remembered that results obtained from a limb, in which the dissection has proceeded so far, are apt to be deceptive. In the case of the proximal radio-ulnar joint the movement is simple enough. The head of the radius merely rotates within the annular ligament, and accuracy of motion is obtained by the fovea capituli radii resting and moving upon the rounded capitellum of the humerus. But it should be noticed that the head of the radius does not fit accurately upon the capitellum in all positions of the elbow-joint. In extreme extension and extreme flexion of the elbow it is only partially in contact with it. Therefore the semi-flexed condition of the elbow-joint places the radius in the most favourable position for free and precise movement at the proximal radio-ulnar joint. At the distal radio-ulnar joint the distal end of the radius revolves around the distal end of the ulna. It carries the hand with it, and describes the arc of a circle, the centre of which corresponds to the attachment of the 158 THE UPPER EXTREMITY discus articularis to the distal end of the ulna. In this movement the discus articularis moves with the radius, and travels dorsally on the distal end of the ulna in supination, and towards the volar surface in pronation. But the question may be asked, does the ulna move during pronation and supination ? When the elbow-joint is extended to its fullest extent the ulna remains almost immovable. When, however, pronation and supination are conducted in the semi-flexed limb, the ulna does move. A small degree of lateral movement at the elbow-joint is allowed, and the distal end of the ulna during pronation is carried slightly dorsally and laterally, and in the reverse direction during supination. The muscles which are chiefly concerned in producing supination of the forearm are — the biceps brachii, the brachio-radialis, and the supinator. The biceps brachii, from its insertion into the dorsal part of the tuberosity of the radius, is placed in a very favourable position, in so far as its supinat- ing action is concerned. The muscles which act as pronators of the limb are — the pronator teres, the pronator quadratus, and, to a certain extent, the flexor carpi radialis. The pronator teres, from its insertion into the point of maximum lateral curvature of radius, can exercise its pronating action to great advantage. The balance of power is in favour of the supinators, and this is due to the preponderating influence of the biceps. Dissection. — The annular ligament should be cut through, and the oblique cord and the membrana interossea should be divided proximo- distally. By drawing the radius laterally and opening the capsule of the distal radio-ulnar joint, the proximal surface of the discus articularis of the wrist will be displayed and its attachments more fully appreciated. ARTICULATIONES CARPE^E (CARPAL JOINTS). In the carpus two joints are recognised— 1. Articulatio ossis pisiformis. 2. Articulatio intercarpea. Pisiform Joint. — The pisiform bone articulates with the volar surface of the os triquetrum to which it is attached by a capsular ligament. The cavity of the pisiform joint is quite distinct from those of the adjacent joints. The dissector has previously noted that the tendon of the flexor carpi ulnaris is inserted into the pisiform bone, and as the capsular ligament would be quite incapable by itself of withstanding the strain to which this muscle subjects the articulation, certain accessory bands are provided which anchor the pisiform firmly in place — they are the piso-hamate and the piso-metacarpal bands. The former passes from the distal end of the pisiform to the hook of the os hamatum, and the latter attaches the pisiform to the proximal ends of the fourth and fifth metacarpal bones. ARTICULATIONS ARTICULATIO INTERCARPEA (INTERCARPAL JOINT). The intercarpal joint has one joint cavity, but it includes not only the articulations between the proximal and distal rows of carpal bones which form the transverse part of the joint but also the articulations between the bones of the proximal row and those between the bones of the distal row. The main part of the cavity of the joint lies between the bones of the proximal and distal rows ; but two prolongations pass proximally, one between the os lunaturri and the os naviculare, Recessus sacciformis Os naviculare man us Os capitatum Os mult- angulum minus Os maltangu- lum majus"~~ FIG. 63. — Coronal section through Radio-carpal, Carpal, and Carpo- metacarpal and Inter-metacarpal Joints to show Joint Cavities and Interosseous Ligaments (diagrammatic). and the other between the os lunatum and the os triquetrum, and three diverticula are prolonged between the bones of the distal row, beyond which they become continuous with the cavity of the carpo-metacarpal joint. The bones of the proximal row are connected together by two dorsal, two volar, and two interosseous ligaments, which pass from the os lunatum to the os naviculare and os tri- quetrum. which lie to either side of it. The two interosseous ligaments are composed of short, stout fibres which pass between the non-articular portions of the opposed surfaces of the bones. They are readily seen from the proximal aspect, 160 THE UPPER EXTREMITY where they complete the distal surface of the radio-carpal joint. The members of the distal row of carpal bones are bound together by three dorsal, three volar, and three inter- osseous ligaments which pass transversely between the adjacent bones. The interosseous ligament between the os capitatum and the os hamatum is very strong ; that between the os capitatum and the os multangulum minus is weak and not uncommonly absent. At present the interosseous ligaments between the bones of the distal row are hidden from view, but they can be studied when the transverse part of the intercarpal joint is opened. The transverse part of the intercarpal joint lies between the proximal and distal rows of carpal bones. The two rows of bones are bound together by a capsular ligament which is attached to the volar and dorsal surfaces and the medial and lateral borders of each row. The lateral and medial parts of the capsule are sometimes spoken of as the lateral and medial ligaments of the transverse carpal joint. The volar and dorsal parts of the capsule are strengthened by numerous bands of fibres. The bands on the dorsal surface are irregular in number and strength, but those on the volar surface are better marked and, for the most part, they radiate from the os capitatum to the surrounding bones forming the ligamentum carpi radiatum. One of the bands of this ligament passes from the os capitatum to the styloid process of the radius and blends with the radial collateral ligament of the radio-carpal joint. Articular Surfaces. — The individual bones of the upper row and the individual bones of the lower row articulate with each other by flat surfaces. In the transverse part of the intercarpal articulation the proximal parts of the os capitatum and the os hamatum form a high convexity which fits into a concavity formed by the distal surfaces of the os triquetrum and os lunatum and the distal part of the medial surface of the naviculare of the proximal rows; and the convex distal surface of the os naviculare is received into a concavity formed by the proximal surfaces of the greater and lesser multangular bones. The two opposed surfaces of the trans- verse part of the joint are, therefore, concavo-convex from side to side, and adapted one to the other. ARTICULATIONS 161 Movements at the Carpal Joints.— The movements at the carpal joints supplement those at the radio-carpal joint, and tend greatly to increase the range of movement at the wrist. Between the individual bones of each row the movement is of a gliding character, and very limited. At the trans- verse intercarpal joint volar and dorsal movements (flexion and extension) are alone allowed. By the multiplicity of joints in this part of the limb, strength and elasticity is contributed to the wrist. Dissection. — The interosseous muscles should now be removed from the metacarpal bones. At the same time the flexor tendons and lumbrical muscles may be detached from the fingers. The extensor tendons, how- ever, should be left in position on the dorsal surfaces of the metacarpo- phalangeal and interphalangeal joints. The ligaments which connect the carpus and metacarpus, and those which pass between the bases of the four medial metacarpal bones, should be cleaned and defined. ARTICULATIONES INTERMETACARPE^E (INTERMETACARPAL JOINTS). The four metacarpal bones of the fingers articulate with each other by their basal or proximal extremities, and are united together by strong ligaments. The metacarpal bone of the thumb stands aloof from its neighbours, and enjoys a much greater freedom of movement. The ligaments which bind the four medial metacarpal bones to each other are — 1. A series of volar and dorsal bands which pass trans- versely and connect their basal extremities. 2. Three stout interosseous ligaments, which occupy the intervals between the basal ends of the bones. 3. The transverse ligaments of the heads, which connect the heads or distal extremities of the bones (p. 146). This liga- ment has been removed in the dissection of the interosseous muscles. The interosseous ligaments cannot be seen at present, but can be studied later on by separating the bases of the metacarpal bones from each other. ARTICULATIONES CARPOMETACARPE^E (CARPO-METACARPAL JOINTS). The metacarpal bone of the thumb articulates with the os multangulum majus by a joint which is quite distinct from the other carpo-metacarpal articulations. A capsular ligament surrounds the joint, and is sufficiently lax to allow a very con- VOL. i — 11 1 62 THE UPPER EXTREMITY siderable range of movement. On the dorsal and lateral aspects of the articulation it is specially thickened. Its cavity is distinct from that of the adjacent articulations. The four medial metacarpal bones are connected to the carpus by volar and dorsal ligaments, and by one interosseous ligament. Each of these metacarpal bones, with the exception of the fifth, possesses, as a rule, two dorsal ligaments and one volar ligament. The articulation of the fifth metacarpal bone is also closed on the medial side by ligamentous fibres. The interosseous ligament springs from the contiguous distal margins of the os capitatum and os hamatum, and passes to the medial side of the base of the third metacarpal bone. Dissection. — To display this ligament, divide the bands which connect the bases of the third and fourth metacarpal bones, and sever the dorsal ligaments which bind the two medial metacarpal bones to the carpus. The metacarpal bones thus set free can then be forcibly bent volarwards, when the ligament in question will come into view. Synovial Membranes of the Carpal, Carpo-metacarpal, and Intermetacarpal Joints. — The articulations between the os pisiform and the os triquetrum as well as the carpo- metacarpal joint of the thumb both possess separate capsules, but the various ligaments of the intercarpal, carpo-metacarpal, and proximal intermetacarpal joints, though they are spoken of individually as separate ligaments, constitute collectively a single capsule, which surrounds a continuous joint cavity. The synovial membrane of the capsule is prolonged over all parts of the bones, enclosed within the capsule, which are not covered by articular cartilage, and it is continued proximally between the three bones of the proximal row of the carpus as far as the interosseous ligaments which connect the bones together. It covers the distal surfaces of these ligaments and is excluded by them from the radio-carpal joint. It passes also between the four bones of the distal row of the carpus and covers the inner surfaces of the ligaments of the carpo-metacarpal joints and the ligaments of the four medial intermetacarpal articulations. In some cases the interosseous ligament which connects the base of the third metacarpal to the os capitatum and os hamatum shuts off the articulation of the os hamatum with the two medial metacarpal bones, and converts the articulation of the os hamatum with the two medial metacarpal bones into a separate segment of the carpo-metacarpal joint. ARTICULATIONS 163 Dissection. — To display the articular surfaces of the carpo-metacarpal articulations, the metacarpus should be detached from the carpus. The interosseous ligaments between the carpal bones of the second row, and also between the bases of the four medial metacarpal bones, can likewise be demonstrated by carrying the knife between the bones, and dividing the ligaments. Articular Surfaces. — The base of the metacarpal bone of the index will be seen to be hollowed out for the reception of the os multangulum minus. On the lateral side it likewise articulates with the os multangulum majus, and on the medial side with the os capitatum. The base of the third metacarpal rests against the os capitatum alone. The base of the meta- carpal bone of the ring finger rests upon the os hamatum, but also articulates slightly with the os capitatum. The fifth metacarpal bone articulates with the os hamatum. Movements of the Metacarpal Bones. — The opposed saddle - shaped surfaces of the os multangulum majus and the metacarpal bone of the thumb allow free movement at this joint. Thus the metacarpal bone of the thumb can be moved — (i) dorso-laterally (extension) ; (2) volarwards and medially (flexion) ; (3) medially towards the index (adduction) ; (4) laterally (abduc- tion) ; (5) medially across the palm towards the little finger (opposition) ; (6) a combination of the above-mentioned movements occurring one after the other constitutes circumduction. The muscles which operate on the thumb are — (i) the two special extensors, brevis and longus, and the abductor pollicis longus producing extension ; (2) the flexor pollicis brevis, the opponens pollicis, and the adductor pollicis producing flexion and opposition, two movements which are similar in character ; (3) the abductor pollicis longus and the abductor pollicis brevis producing abduction ; (4) the adductor pollicis and the first dorsal interosseous muscle which give rise to adduction. The metacarpal bones of the index and middle fingers possess very little power of independent movement. The metacarpal bone of the ring finger, and more especially the metacarpal bone of the little finger, are not so tightly bound to the carpus. When the hand is clenched they both move volarwards. The metacarpal bone of the little finger is provided with an opponens muscle, and has a feeble power of moving volarwards and laterally towards the thumb. ARTICULATIONES METACARPOPHALANGE^E (METACARPO- PHALANGEAL JOINTS). The slightly cupped base of the first phalanx of each digit articulates with the rounded head of the corresponding metacarpal bone, and is held in position by (i) a capsule; (2) two ligg. collateralia, and (3) by a lig. accessorium volare. Lig. Accessorium Volare (O.T. Anterior Ligament). — The volar accessory ligament is a dense fibrous plate placed on the volar aspect of the joint. It is firmly attached to the base i— 11 a 1 64 THE UPPER EXTREMITY of the phalanx, but only slightly connected with the meta- carpal bone. Occupying the interval between the two col- lateral ligaments it is united to both by its margins, so that the three ligaments are more or less directly continuous. The volar accessory ligament also exhibits a close connection with the transverse ligament of the heads of the metacarpal bones which stretches transversely across the heads of the metacarpal bones, and its volar surface is grooved for the flexor tendons as they proceed distally over the joint. Further, the fibrous sheath, which bridges over the tendons, is fixed to its borders. Ligg. Collateralia (O.T. Lateral Ligaments). — The col- lateral ligaments are placed one on either side of the joint. Each is a strong, thick, and short band, which is attached, on the one hand, to the tubercle and depression on the corresponding side of the head of the metacarpal bone, and on the other to the base of the phalanx and the border of the volar ligament. Dissection. — The extensor tendon should now be raised from the dorsal aspect of the joint. By this proceeding the joint is opened, and a demonstration is afforded of the fact that the metacarpo-phalangeal joints are only represented dorsally by the stratum synoviale. Stratum Synoviale (Synovial Membrane). — A synovial membrane lines the deep surfaces of the capsula articularis in each joint, and also the deep surface of the extensor tendon, as it passes over the articulation. The tendon there- fore takes the place of the stratum fibrosum of the capsule. Movements at the Metacarpo-phalangeal Joints. — The movements of the first phalanx at these joints are — (a) flexion^ or volar movement ; (b) extension, or dorsal movement ; (c) abduction ; and (d) adduction. During flexion of the fingers the first phalanx travels volarwards with the thick accessory volar ligament upon the head of the metacarpal bone. The interosseous and lumbrical muscles are chiefly instrumental in producing this movement. The first phalanges of the fingers in the movement of extension can only be carried dorsally to a very slight degree beyond the line of the metacarpal bones. The extensor conwmnis and the special extensors of the index and little finger are the muscles which operate in this case. Abduction and adduction are movements of the first phalanx away from and towards a line prolonged distally through the middle finger, and are seen when the fingers are spread out and again drawn together. The abductor digiti quinti and the dorsal interosseous muscles act as abductors of the fingers at these joints, whilst the volar interosseous muscles operate as adductors of the little, ring, and index fingers. In the case of the middle digit, the second and third dorsal interosseous muscles act alternately as abductors and as adductors. In connection with the ARTICULATIONS 165 movements of abduction and adduction, it should be noticed that in the extended position of the fingers they are very free ; but if flexion be induced, the power of separating the fingers becomes more and more restricted, until it becomes absolutely lost when the hand is closed. An examination of the collateral ligaments will afford the explanation of this. These "are attached so far dorsally on the metacarpal bones, as to be much nearer to their distal ends than to their volar aspects " (Cleland). Consequently, while they are comparatively lax in the extended position of the fingers, the further flexion advances the tighter they become, and in this way they interfere with the lateral movements of the first phalanges. The first phalanx of the thumb has only a limited range of movement at the metacarpo-phalangeal joint. ARTICULATIONES DIGITORUM (JOINTS OF THE FINGERS). The ligaments connecting the phalanges are arranged upon a plan identical with that already described in connection with the metacarpo-phalangeal joints. This should not be made an excuse, however, to slur them over. Movements. — From the manner in which the articular surfaces are adapted to each other, flexion and extension are the only movements which can take place at the interphalangeal joints. Flexion of the second phalanges of the fingers is brought about by the flexor sublimis, and of the ungual phalanges by the flexor profundus. Extension of the phalanges at the interphalangeal joints is largely produced by the interosseous and lumbrical muscles acting through the extensor tendons, into which they are inserted. These muscles, therefore, whilst they flex the first phalanx at the metacarpo-phalangeal joints, extend the second and ungual phalanges at the interphalangeal joints. In the case of the thumb, the long flexor and the extensor pollicis longus operate at the interphalangeal joint. r— 11 6 i66 INFERIOR EXTREMITY INFERIOR EXTREMITY. THE THIGH. ON the morning of the fourth day after the subject has been brought into the dissecting room it is placed upon the table lying upon its back, the pelvis is supported by two blocks, and the inferior extremities are stretched out at full length. In this position it is allowed to remain for five days and during that period the dissector of the inferior extremity has a very extensive dissection to perform. He has to dissect (i) the anterior region of the thigh, including the trigonum femorale and its contents, (2) the medial region of the thigh, in- cluding the adductor canal and its contents. With so much work to be completed, within a limited time, he must appor- tion the five days to the best advantage. During the first day he should dissect the superficial structures of the whole of the anterior and medial aspects of the thigh. During the second and third days he should complete the dissection of the femoral triangle and the anterior region of the thigh, and the remainder of the period should be devoted to the dissec- tion of the medial region. Surface Anatomy. — Before the skin is reflected the surface markings of the anterior, the lateral, and medial region of the thigh must be examined. A faint sulcus at the superior extremity of the anterior region is the boundary line between the inguinal region of the abdomen and the subinguinal region of the thigh. The resistance felt deep to the sulcus is due to the ligamentum inguinale (O.T. Pouparfs Ligament] which is attached, at the lateral and superior end of the sulcus, to the anterior superior iliac spine, and its inferior and medial end to the tubercle of the pubis. From the anterior superior iliac spine the crista iliaca can be traced laterally and dorsally, and from the pubic tubercle the finger should be carried medially, along the pubic crest, to the superior end of the symphysis pubis. Next the finger should be passed downwards, along the front of the symphysis pubis, to the superior margin of the arcus pubis and. thence downwards and dorsally, along the rami of the pubis and ischium, which mark the superior boundary of the medial femoral region, to the tuber THE THIGH 167 ischiadicum. About four inches below the highest part Sternal end of clavicle Acromial end of clavicle Head of humerus - Nipple Lower end of body of sternum Junction of manubrium /ith body of sternum Lateral epicondyle Medial epicondyle Ant. sup. spine of ilium Great trochanter • Styloid process of radius Styloid process of ulna it . M Symphysis of pubis Lower end of radius Medial condyle of femur Lateral condyle of femur Patella Tibia Head of fibula ' Lateral malle Medial malleolus Lateral malleolus FIG. 64. — Anterior Surface of Body. of the iliac crest, and on the plane of the pubic ridge, is the regio trochanterica, indicated by an eminence due to the i. -lie 1 68 INFERIOR EXTREMITY prominence of the trochanter major of the femur. Above the trochanteric region, and between it and the crista iliaca, is the regio coxa (hip), and below the trochanteric region is the regio femoris lateralis. At the distal end of the anterior part of the thigh is the regio genu anterior. In the centre of the anterior part of the knee lies the patella or knee-cap, the outline of which can be seen as well as felt. When the limb is extended the extensor muscles in the anterior part of the thigh are relaxed and the patella is freely movable. As the /eg is flexed on the femur at the knee the patella passes distally, till it lies in front of the interval between the femur and the tibia, and \hz fades patellaris of the femur can be felt beneath the skin. From the distal end of the patella the lig. patellae should be followed to the tuberosity of the tibia. At the distal end of the lateral region of the thigh the outline of the lateral condyle of the femur is easily recognised. Directly below it is the lateral condyle of the tibia, and at the distal and posterior part of the latter the head of the fibula. The tendon which can be traced proximally from the capitulum fibulae, on the border line between the lateral and posterior femoral regions, is the tendon of the biceps femoris, and the dense longitudinal band of fascia immediately anterior to the tendon of the biceps is the tractus ilio-tibialis of the fascia lata — a fascial band which is more easily distinguishable in the living than in the dead body. At the distal end of the medial part of the thigh is the outline of the medial condyle of the femur which should be palpated, and immediately distal to it the medial condyle of the tibia is easily recognised beneath the integument. The tendons posterior to the medial condyle of the femur, which also are more easily felt in the living than the dead body, are the tendons of the semitendinosus and semirnembranosus muscles, and the less easily palpated tendon of the adductor magnus should be distinguished as it descends to the superior border of the medial femoral condyle. The dissector should verify all the above-mentioned points of surface anatomy not only on the dead body but also on the bodies of himself and his friends, and he should examine them repeatedly until he is quite familiar with them both by sight and touch. THE THIGH 169 SUPERFICIAL DISSECTION. This dissection comprises the examination of the following parts :— 1. Superficial fascia. 2. Vena saphena magna and its tributaries. 3. Art. Pudenda externa superficialis. 4. Art. Epigastrica superficialis. 5. Art. Circumflexa ilium superficialis. 6. Lymph glands and vessels. 7. The fossa ovalis. 8. Cutaneous nerves. 9. The fascia femoris. 10. The bursae patellae. Reflection of the Skin. — Incisions, — (i) From the anterior superior iliac spine along the line of the inguinal ligament to the symphysis pubis ; (2) from the medial extremity of the first incision distally along the margin of the scrotum, then along the junction of the medial with the posterior aspect of the thigh and across the medial aspect of the knee to the level of the tuberosity of the tibia ; (3) from the distal end of the vertical incision transversely across the anterior surface of the leg to its lateral border. The quadrilateral flap of integument thus mapped out must be raised carefully from the subjacent superficial fascia and turned laterally, particular care being taken in the region of the knee to avoid injury to the patellar plexus of cutaneous nerves. Panniculus Adiposus (Superficial Fascia). — The fatty super- ficial fascia which is now exposed is continuous with the corresponding layer on the front of the abdomen, and it is regarded by some anatomists as being composed of two layers. This subdivision is needless and artificial. In the lower part of the abdominal wall, above the inguinal liga- ment, it is true the superficial fascia presents two distinct strata — one a fatty layer continuous, over the inguinal liga- ment, with the superficial fascia of the anterior part of the thigh, and sometimes termed the fascia of Camper •• the other, a deeper layer, firm and membranous and devoid of fat, called the fascia of Scarpa. As this latter fascial stratum is attached to the fascia femoris (deep fascia of the thigh) immediately below the inguinal ligament, it is necessary that it should receive some attention. To demonstrate the fascia of Scarpa the dissectors of the lower extremity and abdomen should work in conjunction with each other. A transverse incision should be made through the entire thickness of the superficial fascia on the front of the abdomen, from the anterior superior spine of the ilium to the medial line of the body. On raising the lower edge of i yo INFERIOR EXTREMITY the divided fascia the two layers can be easily distinguished. Insinuate the fingers between the fascia of Scarpa and the pearly-looking tendon of the external oblique muscle. Little resistance will be encountered, as it is only bound down by some lax areolar tissue. The fingers can be readily carried down- wards behind the fascia of Scarpa as far as the inguinal liga- ment. Here it will be found that they can force their way no farther. The passage of the hand into the thigh is barred by the blending of the fascia of Scarpa with the fascia lata, along an oblique line immediately below the inguinal ligament. At this level, therefore, it ceases to exist. The fatty super- ficial layer of Camper, however, as we have said, is continued onwards as the superficial fascia of the thigh. When urine is effused under the superficial fascia of the anterior abdominal wall, the attachment of the fascia of Scarpa to the fascia lata prevents its passage downwards in front of the thigh. Dissection. — In the superficial fascia, blood-vessels, glands, lymph vessels, and nerves are embedded, and these must now be dissected out. First look for the great saphenous vein. It will be found running proxi- mally from the posterior border of the medial condyle of the femur to a point about one and a half inches distal and lateral to the pubic tubercle, where it passes through the fossa ovalis into the femoral triangle to join the femoral vein. It is not desirable to define the opening in the fascia femoris through which it passes until a later stage of the dissection. Several tributaries join the great saphenous vein at this point, and these should be dissected along with the small superficial arteries of the groin which accompany them. The large lymph glands of the groin must also be dissected out from the fatty tissue in which they lie. In doing this care must be taken to preserve as many as possible of the minute thread-like lymph vessels which enter and leave the glands. A small artery and vein should also be traced to each gland. Superficial Inguinal Vessels. — Three minute arteries, termed the superficial epigastric, the superficial external pudendal and the superficial circumflex iliac, pierce the fascia femoris below the inguinal ligament, and radiate from each other for the supply of the lymph glands and integument of the subinguinal region. They all spring from the femoral artery immediately after it enters the thigh. Art. Pudenda externa superficial . — The superficial external pudendal comes forward through the fascia cribrosa (a thin fascial layer, which is spread over the fossa ovalis), and runs medially and upwards across the spermatic cord. It supplies the skin of the scrotum and penis. THE THIGH 171 Art. Epigastrica superficial! s. — The superficial epigastric turns upwards and leaves the thigh by crossing the inguinal ligament about its middle. It is distributed chiefly to the skin on the front of the abdomen. Cut edge of Scarpa's fascia Nervus lumboinguinalis Femoral vessels Margo falciformis, cornu superius Annulus inguinalis subcutaneus Pectineal part of fascia femoris Spermatic cord ' A. pudenda externa I superficial A. epigastrica superficial A. circumflexa ilin superficialis Lymph gland Iliac portion of fascia lata N. cutaneus femoris laterz Margo falciformis (corni inferius) of fossa ovalis V. saphena mag Anterior and posterior ( branches of the medial < cutaneous nerve (O.T. v. — internal cutaneous) FIG. 65. — Superficial Dissection of the Proximal Part of the Anterior Region of the Thigh. The fossa ovalis (O.T. saphenous opening), the superficial lymph glands and vessels of the groin are displayed. The lymph vessels may be recognised by their beaded appearance. Art. Circumflexa ilium superficialis. — The superficial circum- flex iliac is very minute, and courses upwards and laterally, along the inguinal ligament, towards the anterior superior spine of the ilium. The veins which accompany these arteries converge to- 172 INFERIOR EXTREMITY wards the fossa ovalis and join the great saphenous vein before it pierces the fascia. Lymph Glands and Vessels. — The disposition of the super- ficial lymph glands into two groups will now be evident — a proximal inguinal group along the line of the inguinal ligament, immediately distal to the attachment of Scarpa's fascia to the fascia lata, and a distal group, the superficial subinguinal glands, which extends for a short way down the thigh along the line of the great saphenous vein. In a spare subject, or, better still, in a dropsical subject, the general arrangement of the lymph vessels may also be made out. To the subinguinal group of glands proceed the vessels of the lower extremity ; to the inguinal group of glands go the lymph vessels from the genitals, perineum, and the surface of the abdomen. These are termed the afferent vessels. In addition to these, numerous vessels pass between the various glands and connect them with each other. The lymph vessels which lead the lymph away from the glands are called the efferent vessels. A large number of these pass through the fossa ovalis, others pierce the fascia lata. They join the deep subinguinal glands and the external iliac glands which lie in relation to the femoral and external iliac arteries. Dissection. — It has already been noted that an opening in the fascia lata called the fossa ovalis (O.T. saphenous opening] is situated at the proximal and medial angle of the anterior part of the thigh. It is bounded proximally, laterally, and distally by a sharp crescentic margin, the margo falciformis, and through it pass the great saphenous vein, on its way to join the femoral vein, and the efferent lymph vessels which connect the inguinal lymph glands and the superficial subinguinal lymph glands with the deep subinguinal lymph glands. The deep fascia on the lateral side of the fossa ovalis is called the iliac portion of the fascia lata, and that on its medial side is the fascia pectinea. It is difficult to display the opening satisfactorily but the difficulty may be overcome by the exercise of a little care. The dissector should commence by raising the proximal part of the great saphenous vein from the fatty bed in which it lies ; he should then carry the handle of his scalpel upwards behind the vein till he feels it dip backwards over a sharp free margin, the cornu inferius of the opening. This cornu is always clearly defined. It blends medially with the fascia pectinea, which lies superficial to the pectineus and adductor longus muscles. Laterally it is continued upwards into the lateral part of the margo falciformis, and the proximal end of the latter, turning medially, becomes the cornu superius which gains attachment to the distal and medial part of the lig. lacunare (O.T. Gimbernat's ligament). The margo falci- formis and the cornu superius are not always easy to define, but if the dissector, after he has displayed the cornu inferius, will carefully remove the superficial fat from the surface of the fascia, on the lateral side of the great saphenous vein, he will find that at a short distance from the vein the iliac portion of the fascia lata suddenly becomes thinner. The sudden THE THIGH 173 thinning indicates the position of the lateral part of the margo falciformis, which should be defined by the edge of the knife and then traced proxhnally and medially into the cornu superius. When the lateral part of the margo falciformis is displayed the dissector should return to the cornu inferius and trace it to its fusion with the fascia pectinea ; then he should clear away the superficial fascia from the surface of the latter. As he does this he will recognise that, above the level of the cornu inferius, the fascia pectinea does not pass across the front of the femoral vessels to join the iliac portion of the deep fascia, but, on the contrary, it dips posterior to the femoral vessels to become continuous with the deep intermuscular septa. In a sense, therefore, the margo falciformis forms the medial free margin of the iliac part of the fascia lata (see Fig. 65). In reality, however, a thinner layer of fascia is continued from this margin across the front of the sheath of the femoral vessels to join the fascia pectinea. This thinner layer of fascia which closes the fossa is known as the fascia cribrosa, because it is perforated by the great saphenous vein and by the efferent vessels of the inguinal and subinguinal lymph glands on their way to join the deep subinguinal lymph glands. When the margins of the fossa ovalis have been displayed, the inguinal and subinguinal lymph glands and the fascia cribrosa should be removed, care being taken, during the removal of the latter, to avoid injury to the femoral sheath which lies subjacent to them. Fossa Ovalis (O.T. Saphenous Opening). — This is the aperture in the deep fascia through which the great saphenous vein passes to its junction with the femoral vein. A thin fascia, called the fascia cribrosa, is spread over the opening. Difference of opinion exists as to what the fascia cribrosa really is. It is regarded by some as being a part of the superficial fascia, but it is more correct to look upon it as being a thin layer of fascia lata carried over the opening, or, in other words, a prolongation medially of the lateral margin of the opening. The fossa ovalis is of special importance, because it is the opening through which femoral hernia makes its way to the surface. It is oval in shape and not more than half an inch in width ; but it is at least one and a half inches long. Its medial boundary, which is formed by the receding fascia pectinea, lies on a deeper plane than the lateral boundary. The lateral boundary or margo falciformis is crescentic. It is formed by the iliac portion of the fascia lata. The cornu inferius of the falciform edge curves medially, distal to the proximal end of the great saphenous vein, to join the fascia pectinea. The cornu superius (sometimes called Hey's liga- ment), not so well defined, sweeps medially, anterior to the proximal part of the femoral sheath, and joins the front of the lig. lacunare (O.T. Gimbernat's ligament) (Fig. 65). 174 INFERIOR EXTREMITY Dissection. — Clean the great saphenous vein proximo-distally, taking care to avoid injuring any of the branches of the cutaneous nerves which lie close to it. In the proximal part of the thigh it is accompanied by branches of the medial cutaneous nerve (O.T. internal cutaneous), one of the anterior cutaneous branches of the femoral nerve. In the distal part of the thigh it is accompanied by the anterior branch of the same nerve and it passes across the medial and posterior aspect of the knee, where it is accompanied by the saphenous nerve. Clean also the tributaries of the vein and avoid injury to the cutaneous nerves which they cross. Vena Saphena Magna (O.T. Internal Saphenous Vein).— This is the largest superficial vein of the inferior extremity. It commences on the dorsum of the foot, passes proximally anterior to the medial malleolus and across the medial surface of the distal third of the tibia, and then along the medial margin of the tibia. It enters the area of dissection at present under consideration at the level of the tuberosity of the tibia, passes proximally across the posterior part of the medial aspect of the knee, then further proximally, with an inclination anteriorly and laterally, through the medial region of the thigh to the fossa ovalis, where it pierces the fascia cribrosa and the femoral sheath and terminates in the femoral vein. In its course through the thigh it receives tributaries from the anterior and medial regions, the former constitute the lateral femoral circumflex veins and the latter the medial femoral circumflex veins ; one of the latter not uncommonly connects the great saphenous veins with the small saphenous vein. Just before it pierces the fascia cribrosa the great saphenous vein is joined by the small veins which correspond with the three superficial arteries of the subinguinal region. Nervi Cutanei (Cutaneous Nerves). — The cutaneous nerves are now to be looked for in the superficial fascia. The main stems are six in number, and are derived from two sources. Three come directly from the lumbar plexus, and three are branches of the femoral nerve : — ( Ilio-inguinalis. From lumbar plexus, \ Lumboinguinalis. ( Lateral cutaneous of the thigh. {Intermediate cutaneous. Medial cutaneous. Saphenous. N. Ilio-inguinalis. — The ilio-inguinal nerve will be found as it escapes from the subcutaneous inguinal ring (O.T. ext. abdominal) in company with the spermatic cord. Its branches THE THIGH 175 go for the most part to the scrotum, but some are distributed to the skin on the proximal and medial parts of the thigh. Nervus Lumboinguinalis (O.T. Crural branch of Genito- crural) pierces the fascia lata a little way distal to the inguinal ligament, and to the lateral side of the femoral artery. With a little care a communication between this nerve and the intermediate cutaneous may be made out. It supplies a limited area of skin on the proximal part of the anterior aspect of the thigh. N. Femoris Lateralis (O.T. External Cutaneous). — The lateral cutaneous nerve of the thigh is distributed on the lateral area of the thigh. It pierces the fascia lata in two parts. Of these, one — the posterior division — appears about two inches distal to the anterior superior iliac spine, and proceeds dorsally and distally ; some twigs of it may be followed to the lower part of the glutseal region. The anterior division comes to the surface about two inches distally. It is the larger of the two, and has a wide area of distribution. It may extend to the knee-joint. Previous to its division the lateral cutaneous nerve of the thigh lies in a prominent ridge of the fascia lata, which descends vertically from the anterior superior spine of the ilium. This must be split up to expose the nerve. The intermediate and medial cutaneous nerves belong to the "rami cutanei anteriores of the n. femoralis," but for convenience and for the purposes of more precise description, they are defined by special names. The intermediate cutaneous nerve (O.T. middle cutaneous nerve] of the thigh, a branch of the femoral nerve, pierces the fascia lata in the middle line of the thigh about three or four inches distal to the inguinal ligament. It usually appears as two branches which perforate the fascia at two points a short distance apart from each other. Both branches extend distally to the knee, which they reach on its medial aspect. The medial cutaneous nerve (O.T. internal cutaneous nerve] of the thigh, a branch of the femoral nerve, following the example of the n. cutaneus femoris lateralis and the inter- mediate cutaneous nerve, divides into two portions — an anterior and a posterior — which perforate the deep fascia on the medial aspect of the thigh, and at some distance apart from each other. The anterior division makes its appear- ance through the fascia lata in the distal third of the thigh, anterior to the great saphenous vein. It descends towards i76 INFERIOR EXTREMITY the knee, and its terminal branches turn anteriorly and later- ally to the anterior aspect of the patella. The pos- terior division reaches the surface on the medial side of the knee, posterior to the great saphenous vein, and proceeds distally to supply the integument on the medial side of the proximal part of the leg. But the main stem of the medial cutaneous nerve, before it divides, likewise sends a few twigs through the fascia lata to reach the skin on the proximal and medial aspect of the thigh. These make their appear- ance along the line of the great saphenous vein. N. Saphenus (O.T. Long Saphenous). — The saphen- ous nerve becomes cutaneous on the medial side of the knee by perforating the fascia between the tendons of the sartorius and gracilis muscles. The guide to it is the saphenous branch of the a. genu suprema, which descends alongside of it. It follows the course of the great saphenous vein into the leg. Before it pierces the fascia it gives off an infrapatellar branch. The infrapatellar branch N. cutaneus femoris lateralis N. ilio-inguinalis N. lumboinguinalis Branch from medial cutaneous of the thigh Intermediate cuta- neous of the thigh" Medial cutaneous__ of the thigh V. saphena magna- Anterior part of medial cutaneous. of the thigh Ramus infrapatellaris of n. saphenus" V. saphena magna- N. saphenus N. peronaeus superficialis. (O.T. musculo- cutaneous) N. peronseus profundus (O.T. ant. tibia!)' FIG. 66. — Cutaneous Nerves on the Front of the Lower Extremity. pierces the sartorius muscle and the fascia lata on the medial side of the knee, and turns laterally towards the anterior aspect of the joint, below the level of the patella. THE THIGH 177 Four of the cutaneous nerves of the thigh have been found to send twigs to the skin over the knee-joint, viz. the anterior division of the lateral cutaneous nerve of the thigh, the inter- mediate cutaneous, the anterior division of the medial cutane- ous, and the saphenous nerve. These nerves communicate with each other and form an interlacement which is situated over the patella, the ligamentum patellae, and proximal part of the tibia. It is termed the patellar plexus. On the medial side of the thigh two minute cutaneous nerve twigs some- times make their appearance which do not belong to any of the above main cutaneous trunks. One appears below the ilio-inguina'l nerve, and is a twig from the perineal branch of the posterior cutaneous nerve of the thigh ; the other pierces the deep fascia at the middle of the medial area of the thigh, and comes from the obturator nerve. Dissection. — After the cutaneous nerves have been cleaned the remains of the superficial fascia must be removed in order that the fascia lata may be studied. Fascia Lata. — This is the name which is given to that portion of the general aponeurotic investment of the lower extremity which clothes the thigh and preserves its figure. The dissector will be struck with the marked difference in strength which it shows on the lateral and medial aspects of the thigh. Laterally it is so dense and strong that it appears to be more tendinous than aponeurotic in its character. The reason of this is that the tensor fasciae latae muscle and the greater portion of the glutaeus maximus are inserted into it upon this side of the limb. The strong band thus formed goes under the name of the tractus iliotibialis, from its being attached above to the crest of the ilium, and below to the lateral condyle of the tibia and to the head of the fibula. It acts as a powerful brace, on the lateral aspect of the limb, which, in the erect posture, helps to steady the pelvis and at the same time keep the knee-joint firmly extended. Medially, the fascia lata is so exceedingly delicate and thin that the subjacent muscular fibres shine through it, and it is very apt to be removed with the superficial fascia unless care be exercised in the dissection. Superiorly, around the root of the limb, the fascia lata is attached to the inguinal ligament and the bones of the pelvis. Posteriorly, it is continuous with the glutaeal aponeurosis, and through this it is fixed to the coccyx, sacrum, and crest of the ilium. On the lateral side it is attached to the crest .of the ilium ; and on the medial side to the body of the pubis, the VOL. i — 12 178 INFERIOR EXTREMITY margin of the pubic arch, and to the tuber ischiadicum. Anteriorly, its upper attachment is complicated by the presence of the fossa ovalis. This aperture separates the fascia lata into a lateral or iliac portion and a medial or pectineal portion, now known as the fascia pectinea. This subdivision only extends distally to the distal border of the fossa ovalis. The iliac portion is attached along the whole length of the inguinal ligament. Its medial crescentic margin bounds the fossa ovalis laterally and forms its falciform edge. The cornu superius of this edge blends with the lig. lacunare (O.T. Gimbernat's ligament), whilst its inferior cornu joins the pectineal portion of the fascia lata. The fascia pectinea clothes the proxi- mal portions of the adductor longus and pectineus muscles. It recedes from the surface as it is traced laterally, passes posterior to the sheath of the femoral vessels, and blends with the lig. pubocapsulare of the hip - joint, with the deep 67. — Diagram to show the intermuscular septa, and with the fascia iliaca which covers the ilio-psoas muscle. To the medial side of the femoral vessels the fascia pectinea is attached above to the ilio-pectineal line of the pubic bone. The fascia cribrosa, as previously stated, is to be regarded as a thin piece of the fascia lata, stretched across the fossa ovalis. Laterally, it is continuous with the falciform edge of the iliac portion of the fascia ; medially, it blends with the front of the fascia pectinea. In the neighbourhood of the knee the fascia lata is con- tinuous posteriorly with the popliteal fascia, whilst on the lateral and anterior aspects of the joint it is attached to the various bony prominences and to the different tendons in this locality and it helps to strengthen and support the capsular ligament of the knee-joint. Septa Intermuscularia (Intermuscular Septa). — But the fascia . lata has other offices to perform besides that of forming a continuous investment for the thigh. From every part of FIG. arrangement of the three inter- muscular septa and the three osteo-fascial compartments the thigh. (After Turner. ) a. Medial intermuscular septum. of THE THIGH 179 its deep surface processes pass off which penetrate the limb and constitute sheaths for the muscles and other structures which compose it. Three of these, which are especially strong, form distinct septa or partitions which reach the femur and are attached to the linea aspera on its posterior aspect. These partitions are termed the intermuscular septa, and are so dis- posed that they intervene between the three great groups of muscles in this region. The septum intermusculare laterale is placed between the- extensor muscles in the anterior area of the thigh and the hamstring muscles in the posterior region ; the septum intermuscular mediale intervenes between the extensor muscles and the adductor muscles in the medial region ; whilst the septum intermusculare posterius, weak and in- conspicuous in comparison with the other two, is interposed between the adductor and the hamstring muscles. These partitions will be disclosed in the subsequent dissection. In the meantime, merely observe that the medial and the lateral septa show on the surface of the fascia in the lower part of the thigh as white lines. By means of the three septa the thigh is divided into three osteo-fascial compartments, viz. an anterior, containing the extensor muscles and the femoral nerve ; a posterior, holding the hamstrings and the sciatic nerve ; and a medial, for the adductors with the obturator nerve (Fig. 67). Bursae Patellares (Patellar Bursse). — Several mucous bursae are situated in the patellar region, those which lie superficially may be investigated now and the more deeply placed bursae should be examined at later stages of the dissection as opportunity occurs. The bursae are — (i) The subcutaneous prepatellarbursa which lies immediately beneath the skin opposite the distal part of the patella. (2) The subfascial prepatellar bursa situated between the fascia lata superficially and the proximal part of the patella and the adjacent part of the tendon of the quadriceps deeply ; this bursa may be displayed by an incision made through the fascia lata in the area indicated. (3) The subtendinous prepatellar bursa lying between the superficial fibres of the tendon of the quadriceps and the periosteum of the anterior surface of the patella. (4) The suprapatellar bursa. This lies proximal to the patella, posterior to the tendon of the quadriceps and anterior to the distal part of the anterior surface of the femur ; it usually communicates with i— 12 a i8o INFERIOR EXTREMITY the cavity of the knee-joint. (5) The subcutaneous mfra- patellar bursa, placed directly beneath the skin anterior to the proximal part of the ligamentum patella. (6) The deep infra- patellar bursa, which is placed between the ligamentum patellae and the anterior surface of the proximal part of the tibia. The suprapatellar bursa and the deep infrapatellar bursae are practically always present, but one or more of the subcutaneous and subfascial bursae may be absent. Not un- commonly a subfascial and an adjacent subcutaneous bursa may communicate through an aperture in the deep fascia. The subcutaneous bursae are often destroyed during the reflection of the skin, but the deeper bursae can usually be found, if looked for carefully, in the situations mentioned above. DEEP DISSECTION OF THE THIGH In this dissection the following parts require to be examined :-<— 1. The femoral sheath. 2. Nervus lumboinguinalis. 3. Nervus cutaneus femoris lateralis. 4. M. sartorius. 5. Nervus femoralis and its rami. 6. Arteria femoralis and its rami. 7. Vena femoralis. 8. M. ilio-psoas. f Musculus rectus femoris. ,. . Musculus vastus lateralis. 9. M. quadriceps femoris \ Musculus vastus intermedius. I Musculus vastus lateralis. 10. M. articularis germ. 11. M. tensor fasciae latse. 12. Deep part of the tractus ilio-tibialis fasciae latae. 13. Intermuscular septa, lateral and medial. Ligament Inguinale (O.T. Pouparfs Ligament) — Liga- mentum Lacunare (O.T. Gimbernat's Ligament). — Although, properly speaking, both of these ligaments belong more to the abdominal wall than the thigh, it is essential that the dissector should obtain some knowledge of their connections before he proceeds further with the dissection. The inguinal ligament is merely the thickened lower border of the apo- neurosis of the external oblique muscle of the abdominal wall folded backwards upon itself. It thus presents a rounded surface towards the thigh, and a grooved surface towards the THE THIGH 181 abdomen. By its lateral extremity it is fixed to the anterior superior spine of the ilium. Medially, it has a double attach- ment, viz. — (i) to the pubic tubercle, (2) through the medium of the lig. lacunare to the medial part of the pecten pubis (O.T. ilio-pectineal line). The inguinal ligament pursues an oblique course between its iliac and pubic attachments, and at the same time describes a gentle curve, the convexity of Sheath of rectus Aponeurosis of external oblique Intercrural Inguinal ligament (Poupart's) Subcutaneous abdominal ring Lig. inguinale reflexum Lig. lacunare (Gimbernat's) FIG. 68. — Dissection to show the connections of the Inguinal Ligament. which is turned distally. By its distal border it affords attachment to the fascia lata, and when this is divided it loses its curved direction. The ligamentum lacunare (O.T. Gimbernat's) is a small triangular piece of aponeurotic fascia which occupies the interval between the medial part of the inguinal ligament and the medial inch of the pecten pubis — being attached by its margins to both. Its base, which looks laterally, is sharp, crescentic, and free, and abuts against the femoral sheath. The lacunar ligament occupies a very oblique plane ; its femoral surface 1—126 1 82 INFERIOR EXTREMITY looks distally and laterally, whilst its abdominal surface is directed upwards and medially. Dissection. — The exposure of the femoral sheath is the next step in the dissection of the thigh. To attain this object the iliac portion of the fascia lata must be partially reflected. Divide the superior horn of the lateral crescentic margin of the fossa ovalis, and then carry the knife laterally along the lower border of the inguinal ligament, so as to sever the attachment of the fascia lata to this thickened band. This incision should extend to within an inch of the anterior superior spine of the ilium. The piece of fascia marked out by the incision above, and by the lateral free margin of the fossa ovalis medially, must be carefully raised from the subjacent femoral sheath and thrown distally and laterally. On the removal of a little loose fat, the femora! sheath will be brought into view as it enters the thigh under the inguinal ligament. Isolate it carefully from adjacent and surrounding parts, by carrying the handle of the knife gently round it — insinuating it first between the sheath and the inguinal ligament, then between the sheath and the lacunar ligament, which lies medial to it. Femoral Sheath. — The funnel-shaped appearance of the femoral sheath will now be apparent — the wide mouth of the membranous tube being directed upwards into the abdomen, and the narrow inferior part gradually closing upon the vessels, and fusing with their coats about the level of the distal limit of the fossa ovalis. Whilst it presents this appearance, however, it should be noticed that its sides do not slope equally towards each other. The lateral border of the sheath is nearly vertical in its direction, whilst the medial wall proceeds very obliquely distally and laterally. If the dissection has been successfully performed, the lumbo-inguinal nerve should be seen piercing the lateral wall of the sheath, whilst the great saphenous vein, and some lymph vessels, perforate its anterior and medial walls. Further, if the subject be spare and the fasciae well marked, the dissector will in all probability notice that the anterior wall of the sheath, in its proximal part, is strengthened by some transverse fibres which pursue an arched course across it. To these fibres the name of deep femoral arch is given, in contradistinction to the term superficial femoral arch, which is sometimes applied to the inguinal ligament. In favourable circumstances the deep femoral arch may be observed to spring from the deep surface of the inguinal ligament about its middle. After traversing the front of the sheath the band expands somewhat, and is attached by its medial extremity to the ilio-pectineal line or pecten of the pubic bone behind the lacunar ligament. Constitution of the Femoral Sheath. — The source from THE THIGH 183 which the femoral sheath is derived, and the manner in which it is formed, must next be considered. This entails the study of some of the structures concerned in the construc- tion of the abdominal wall. Unfortunately it is not likely that, at this period, the dissection of the abdomen is in a sufficiently advanced state for their examination. A small portion of the medial part of the interval between the inguinal ligament and the portion of the innominate bone over which it stretches is filled up by the lacunar ligament. Immediately to the lateral side of this the femoral vessels, enclosed within the femoral sheath, enter the thigh from the abdominal cavity, whilst still more laterally the interval is occupied by the ilio-psoas muscle. Three nerves also find their way into the thigh through the interval, viz. the lumbo-inguinal nerve, which passes distally in the femoral sheath ; the femoral (O.T. anterior crural) nerve, which occupies the interval be- tween the psoas and iliacus muscles ; and the lateral cutaneous nerve of the thigh, which runs behind the inguinal ligament close to its iliac attachment. The arrangement of the aponeurotic lining of the abdominal cavity with reference to this interval of communi- cation between abdomen and thigh also requires attention. The lower part of the posterior wall of the abdomen, immedi- ately above the thigh, is formed by the iliacus and psoas muscles. These are covered by that part of the aponeurotic lining of the abdomen which receives the name of the fascia iliaca.1 The anterior wall of the abdomen is lined in like manner by a portion of the general lining, termed the fascia transversalis. To the lateral side of the femoral vessels these two fascial layers become continuous with each other, and at the same time are attached to the back of the inguinal liga- ment. It is behind this union that the ilio-psoas, the femoral nerve, and the lateral cutaneous nerve of the thigh are carried distally into the thigh. But the external iliac vessels (which become the femoral vessels in the thigh) with the lumbo-inguinal nerve lie anterior to the fascia iliaca, or, in other words, within the fascial lining of the abdomen, and, as they proceed distally behind the inguinal ligament, they carry with them a 1 The dissector must bear in mind the distinction between \h& fascia iliaca and the iliac portion of the fascia lata. The former is a part of the general aponeurotic lining of the abdomen, and the latter is a part of the fascial invest- ment of the thigh. 184 INFERIOR EXTREMITY funnel-shaped prolongation of the lining. This, then, is the femoral sheath, and the dissector will now readily understand that the anterior wall of the sheath is formed si fascia transversalis from the anterior wall of the abdomen above the inguinal ligament, while the posterior wall is formed of fascia iliaca, prolonged downwards from the posterior abdominal wall. Posterior Wall of the Femoral Sheath. — There are still N. cutaneous femoris lateralis M. ilio-psoas Ligamentum inguinale A. femoralis Femoral sheath V. femoralis Lig. lacunare Tuberculum pubicum M. pectineus FASCIA ILIAC/k FlG. 69. — Dissection to show the Femoral Sheath and the other Structures which pass between the Inguinal Ligament and the Innominate Bone. some additional facts relating to the posterior wall of the femoral sheath which require to be mentioned. It is formed, as stated above, by the fascia iliaca; but as this enters the thigh it blends with the fascia pectinea, and further, it is firmly fixed in position by certain connections which it establishes in the thigh. Thus beyond the femoral sheath it is prolonged laterally over the ilio-psoas muscle, whilst from its posterior aspect a lamina is given off which passes posterior to that muscle and joins the capsule of the hip- jo int. THE THIGH 185 Dissection. — The femoral sheath should be opened, in order that the arrangement of parts inside may be displayed. Make three vertical and parallel incisions through the anterior wall — one over the femoral artery which occupies the lateral part of the sheath, another over the femoral vein, and the third about half an inch medial to the second. The first two should begin at the level of the inguinal ligament, and should extend distally for an inch and a half. The most medial of the three incisions should commence at the same point, but should only be carried distally for half an inch or less. Interior of the Femoral Sheath. — A little dissection will show that the sheath is subdivided by two vertical partitions into three compartments. The femoral artery and lumbo- inguinal nerve occupy the most lateral compartment'., the femoral vein fills up the intermediate compartment', whilst in the most medial compartment is lodged a little loose areolar tissue, a small lymph gland, and some lymph vessels. This last compartment, from its relation to femoral hernia, has the special name of canalis femoralis applied to it. Canalis Femoralis (Femoral Canal). — The boundaries and extent of this canal must be very thoroughly studied. The best way to do this is to introduce the little finger into the canal and push it gently upwards. The length of the canal is not nearly so great as that of the other two compartments. Indeed it is not more than half an inch long. Inferiorly it is closed, and it rapidly diminishes in width from above downwards. Its proximal aperture lies on the lateral side of the base of the lacunar ligament, and is called the annulus femoralis. It is closed by the closely applied extra- peritoneal fatty tissue of the abdominal wall. The parts which immediately surround this opening can be readily detected with the finger : laterally the femoral vein, medially the sharp crescentic base of the lacunar ligament, anteriorly the inguinal ligament, and pos- teriorly the pubic bone covered by the pectineus muscle. The portion of the extra-peritoneal fatty tissue which closes the ring is called the septum femorale. On the abdominal surface of the septum femorale is the peritoneal lining of the abdominal cavity, and when examined from above both are seen to be slightly depressed into the opening so as to produce the appearance of a dimple. Femoral Hernia. — Femoral hernia is the name applied to a pathological condition which consists in the protrusion of some of the contents of the abdominal cavity into the region of the thigh. In their descent they i86. INFERIOR EXTREMITY pass behind the inguinal ligament into the canalis femoralis or most medial ^compartment of the femoral sheath. The arrangement of the parts which occupy the interval between the hip bone and the inguinal ligament has been carefully considered, and the dissector should therefore be in a position to understand how the occurrence of such a protrusion is rendered possible. To the medial side of the femoral sheath the interval is closed by the lacunar ligament, which, by its strength and firm connections, constitutes an impassable barrier in this locality. To the lateral side of the femoral sheath a hernial protrusion is equally impossible. There the fascia transversalis on the anterior wall of the abdomen becomes continuous with the fascia iliaca on the posterior wall of the abdomen, and along the line of union both are firmly attached to the inguinal ligament. It is in the region of the femoral sheath, then, that femoral hernia takes place. The three compartments of the sheath open above into the abdominal cavity, but there is an essential difference between the three openings. The two lateral, which hold the artery and the vein, are completely filled up by their contents. The canalis femoralis, or most medial compartment, is not ; it is much wider than is necessary for the passage of the fine lymph vessels which traverse it. Further, its widest part is the upper opening or annuhis femoralis. It has been noted that this is wide enough to admit the point of the little finger, and it forms a weak point in the parietes of the abdomen ; a source of weakness which is greater in the female than in the male, seeing that in the former the distance between the iliac spine and the pubic tubercle is proportionally greater, and in consequence the annulus femoralis wider. Femoral hernia, therefore, is more common in the female. When attempts are made to reduce a femoral hernia, it is absolutely necessary that the course which the protrusion has taken should be kept constantly before the mind of the operator. In the first instance it descends for a short distance in a perpendicular direction. It then turns forward and bulges through the fossa ovalis. Should it still continue to enlarge, it bends upwards over the inguinal ligament, and pushes its way laterally towards the anterior superior spine of the ilium. The protrusion is thus bent upon itself, and if it is to be reduced successfully it must be made to retrace its steps. In other words, it must be drawn distally, and then pushed gently posteriorly and upwards. The position of the limb during this procedure must be attended to. When the thigh is fully extended and rotated laterally all the fascial structures in the neighbour- hood of the canalis femoralis are rendered tight and tense. When the limb is flexed at the hip-joint and rotated medially, on the other hand, the cornu superius of the margin of the fossa ovalis, and even the lacunar ligament, are relaxed. This, then, is the position in which the limb should be placed during the reduction of the hernia. As the hernia descends it carries before it the various layers which it meets in the form of coverings. First it pushes before it the peritoneum, and this forms the hernial sac. The other coverings from within outwards are — (i) the septum femorale ; (2) the wall of the femoral sheath (if it does not burst through one of the apertures in this) ; (3) the fascia cribrosa ; (4) and lastly, the superficial fascia and skin. The femoral canal, as we have noted, is surrounded by very unyielding structures. Strangulation in cases of femoral hernia is therefore a matter of very common occurrence. The sharp base of the lacunar ligament and the superior cornu of the' margin of the fossa ovalis are especially apt to bring about this condition. Abnormal Obturator Artery. — The account of the surgical anatomy of femoral hernia cannot be complete without mention of the relation which the obturator artery frequently bears to the annulus femoralis. In THE THIGH 187 two out of every five subjects the obturator artery, on one or on both sides, takes origin from the inferior epigastric artery. In these cases it passes posteriorly to gain the obturator sulcus in the upper part of the obturator foramen. According to the point at which it arises from the epigastric trunk, it presents different relations to the femoral ring. In the majority of cases it proceeds posteriorly in close contact with the external iliac vein and on the lateral side of the femoral ring. In this position it is in no danger of being wounded in operations undertaken for the relief of a strictured femoral hernia. In about thirty-seven per cent, however, of the Profunda femoris artei Lateral circumflex artery Intermediate cuta- neous nerve (O. T. middle cutaneous) Lateral cutaneous nerve Inguinal ligament (Poupart's) Superficial circumflex iliac artery Femoral nerve | Superficial epigastric and superficial pudendal arteries Deep external ^fc^ /?,' pudendal artery Adductor brevis Femoral vein Great saphenous vein Femoral artery FIG. 70. —Dissection of the Trigonum Femorale. cases, in which it exists, the artery is placed less favourably. In these, it either proceeds posteriorly across the septum femorale which closes the opening into the canalis femoralis, or it arches over it and turns posteriorly on the medial side of the ring upon the deep aspect of the base of the lacunar ligament. In the latter situation it is in a position of great danger, seeing that it is the base of the lacunar ligament against which the surgeon's knife is generally directed for the relief of strictured femoral hernia. 1 Dissection.— The femoral triangle may now be dissected. To bring its boundaries into view the deep fascia must be removed from the anterior the proximal third of the thigh ; in the distal two-thirds, the 1 88 INFERIOR EXTREMITY fascia lata should be left undisturbed, so as to maintain as far as possible the natural position of parts. Trigonum Femorale (O.T. Scarpa's Triangle). — This is the name which is given to the triangular hollow which lies in the proximal part of the thigh below the inguinal ligament The lateral boundary is formed by the sartorius muscle, as it runs distally and medially across the thigh from the anterior superior spine of the ilium ; the medial boundary is constituted by the prominent medial margin of the adductor longus muscle. These muscles meet below to form the apex of the triangle. The inguinal ligament forms the base of the triangle. The contents of the space must now be displayed by remov- ing the fatty areolar tissue which surrounds them. The femoral vessels should first be cleaned. Remove the remains of the femoral sheath and define the various branches which proceed from the vessels in so far as they are seen within the limits of the triangular space. Be careful not to injure the small twig of the femoral nerve which supplies the pectineus ; it passes medially behind the vessels a short distance distal to the inguinal ligament. In this part of its course the femoral artery gives off — ( i ) the three superficial inguinal vessels, which have already been observed ramifying in the superficial fascia of the groin of the subinguinal region ; (2) the deep external pudendal, which runs medially over the pectineus ; (3) the large profunda femoris. The profunda femoris comes off from the lateral side of the femoral artery about one and a half inch below the inguinal ligament. It inclines distally and medially behind the femoral trunk, and soon leaves the space by passing posterior to the adductor longus. The lateral and medial circumflex arteries of the thigh will be seen to arise from the profunda femoris within the femoral triangle. The a. circumflex femoris later alis (O.T. external circumflex) should be traced laterally as it passes amongst the branches of the femoral nerve, to disappear under cover of the lateral boundary of the space. The a. circumflex femoris medialis (O.T. internal circumflex} passes from view, shortly after its origin, by sinking posteriorly through the floor of the space between the pectineus and psoas muscles. The veins corre- sponding to these arteries must be cleaned at the same time. Certain nerves are also to be found in this space, viz. — (i) THE THIGH 189 the lumbo -inguinal nerve ; (2) the lateral cutaneous nerve of the thigh ; and (3) the femoral nerve. The lumbo-inguinal nerve descends in the lateral compartment of the femoral sheath on the lateral side of the femoral artery. It pierces the lateral wall of the sheath and the fascia lata a short distance below the inguinal ligament, and has already been traced to its distribution (p. 175). The lateral cutaneous nerve of the thigh passes into the thigh behind the inguinal ligament, close to the anterior superior spine of the ilium. It soon leaves the femoral triangle by crossing the sartorius and piercing the fascia lata. It has already been traced in its ramifications in the superficial fascia on the lateral aspect of the thigh. The femoral nerve will be detected, lying deeply, in the interval between the psoas and iliacus muscles, about a quarter of an inch to the lateral side of the femoral artery. In- sinuate the handle of a knife under the main trunk, so as to raise it above the level of the muscles between which it lies, and render it tense, and then follow the numerous branches into which it breaks up as far as the limits of the space will allow. The small twig to the pectineus muscle must be looked for. It passes medially, posterior to the femoral vessels. The floor of the femoral triangle slopes backwards both from the medial and the lateral boundary of the space. To the medial side of the femoral artery it is formed by the adductor longus and the pectineus ; in some cases a small portion of the adductor brevis may be seen in a narrow interval between these two muscles. To the lateral side of the artery are the psoas and iliacus. The adductor longus is placed in an oblique plane, the medial border being nearer the surface than the lateral border ; and thus it is that this muscle not only forms the medial boundary of the triangle, but also takes part in the formation of the floor. These muscles should be cleaned in so far as they stand in relation to the femoral triangle. When a transverse section is made through the frozen thigh in the region of the femoral triangle, the space has the appearance of a deep intermuscular furrow, bounded on the medial side by the adductor longus and pectineus, and on the lateral side by the sartorius and rectus femoris, whilst behind it is separated from the bone by the ilio-psoas. The femoral vessels and the femoral nerve pass, distally in this groove — the a. profunda femoris being placed very deeply, whilst the femoral artery lies nearer to the surface. 190 INFERIOR EXTREMITY Arteria Femoralis (O.T. Femoral Artery, Common and Superficial). — The femoral artery, the great arterial trunk of the inferior extremity, is the direct continuation of the external iliac. It begins at the inguinal ligament, behind which it enters the thigh, and it extends distally to the open- ing- in the adductor magnus, through which it gains the fossa poplitea and becomes the popliteal artery. This opening is situated in the distal third of the medial region of the thigh, and the course which the vessel pursues may be marked on the surface, when the thigh is slightly abducted and rotated laterally, by an oblique line drawn from a point midway between the anterior superior iliac spine and the symphysis pubis to the medial condyle of the femur. The relations which the artery bears to the femur are im- portant. As it enters the femoral triangle it passes from the brim of the pelvis and comes to lie in front of the medial part of the head of the femur, from which it is separated by the psoas muscle. Although its relation to the bone is tolerably intimate, this situation should not be chosen for applying compression. On account of the mobility of the head of the bone there is a liability for the vessel to slip from under the fingers. It is much safer to compress it against the brim of the pelvis. Below the head of the femur, during the re- mainder of its course through the femoral triangle, the artery is not in direct relation to the bone. It crosses anterior to the angular interval between the neck and body of the femur. Towards the apex of the space, however, it comes into relation with the medial side of the body of the femur, and this position it holds to its termination. In the present condition of the dissection it is only that part of the femoral artery which traverses the femoral triangle which comes under the notice of the dissector. The length of this part varies with the development of the sartorius muscle, and the degree of obliquity with which this crosses the front of the thigh. It measures from three to four inches in length, and is comparatively superficial throughout its entire course. At the apex of the triangle the femoral artery disappears under cover of the sartorius and takes up a deeper position in the limb. In the femoral triangle the femoral artery is enveloped in its proximal part by the femoral sheath, and is separated from the surface by the skin, superficial fascia, and deep fascia, whilst THE THIGH 191 more distally it is crossed by the medial cutaneous branch (O.T. internal cutaneous) of the femoral nerve, which runs along the medial border of the sartorius muscle. Posterior to the artery are the psoas and pectineus, but it is separated from the psoas by the femoral sheath and the nerve to the pectineus, and from the pectineus by fatty areolar tissue in which lie the profunda femoris artery and the femoral vein. Upon the lateral side of the femoral artery is the femoral nerve1 — but not in apposition with it, as a small portion of the psoas intervenes. The femoral vein changes its position with reference to the artery, as it is traced distally. In the proximal part of the space it lies on the same plane and to the medial side of the artery, but distally it becomes more deeply placed and gradually assumes a position posterior to the artery. The branches which the femoral artery gives off in the femoral triangle have already been enumerated (p. 188). One of these, viz. the deep external pudendal, may now be traced to its destination. Art. Pudenda Externa Profunda (Deep External Pudic). —This is a small twig which arises from the medial side of the femoral, a short distance below the inguinal ligament. It extends medially, upon the pectineus and adductor longus muscles, and, piercing the fascia lata, ends, according to the sex, in the integument of the scrotum or of the labium pudendi. Dissection. — The fascia lata may now be removed from the distal two- thirds of the anterior and medial parts of the thigh. This can best be effected by dividing it along the middle line of the limb, and throwing it laterally and medially. Preserve undisturbed the thickened band of fascia (tractus ilio-tibialis) on the lateral side of the thigh. In cleaning the sartorius muscle several of the nerves of the thigh will be found intimately related to it, and must be carefully dissected. The intermediate cutaneous nerve (O.T. middle cutaneous) frequently pierces its proximal border, and then proceeds distally in front of it ; the anterior branch of the medial cutaneous crosses it more distally, whilst the posterior branch of the same nerve is carried distally along its posterior border. Near the knee it lies superficial to the saphenous nerve, which ultimately comes to the surface between it and the gracilis. A short distance above this the sartorius is pierced by the infrapatellar branch of the saphenous nerve. Lastly, about the middle of the thigh, there is formed under cover of the sartorius, an interlacement of fine nerve twigs derived from the posterior branch of the medial cutaneous, the saphenous nerve, and the obturator nerve. On raising the sartorius from subjacent parts this must be looked for. The different portions of the quadriceps extensor muscle must also be cleaned ; and the branches which the femoral nerve gives to them, and 192 INFERIOR EXTREMITY the descending branch of the lateral circumflex artery must be traced to their terminations. M. Sartorius. — The sartorius is a long slender muscle, which arises from the anterior superior spine of the ilium and Sartorius Muscular artery Adductor longus.,.. 1 Saphenous nerve ---- Nerve to vastus medialis Femoral artery — Rectus femoris - Fascial roof of adductor „ canal (Hunter's) Vastus medialis - Sartorius '- ...Medial cutaneous nerve Great saphenous vein Skin Superficial fascia - Fascia lata - Adductor magnus Fascial roof of adductor "canal (Hunter's) Femoral vein - Semimembranosus Saphenous nerve Medial intermuscular septum Tendon of adductor magnus Sup. genicular artery (O.T. anastomotic) Branches of medial cutaneous nerve FIG. 71. — Dissection of the Adductor Canal (Hunter's) in the right lower limb. A portion of the Sartorius has been removed. the upper part of the notch on the anterior border of the bone immediately below. It crosses the front of the proximal third of the thigh obliquely, and, gaining the medial side of the limb, it takes a nearly vertical course distally to a point beyond the medial prominence of the knee. There it turns forwards, and ends in a thin, expanded aponeurotic tendon, which is THE THIGH 193 inserted into the medial surface of the body of the tibia, posterior to the tuberosity (Fig. 92, p. 248). By its distal border this tendon is connected with the fascia of the leg, whilst by its proximal border it is joined to the capsule of the knee-joint. In its upper oblique part the sartorius muscle forms the lateral boundary of the femoral triangle, and lies anterior to the iliacus, the rectus femoris, and the adductor longus muscles. Distally, it is placed anterior to the femoral vessels as far as the opening in the adductor magnus. At its insertion its ex- panded tendon lies anterior and superficial to the tendons of M. vastus medialis M. vastus intermedius M. sartorius Femoral vessels and n. saphenus in adductor canal (Hunter's) M. adductor longus Femur M. vastus lateralis FlG. 72. — Transverse Section through the Adductor Canal. insertion of the gracilis and semitendinosus, but is separated from them by a bursa. The sartorius is supplied by the anterior division of the femoral nerve. Canalis Adductorius Hunteri (Hunter's Canal).— When the femoral artery leaves the femoral triangle it is continued distally, tin the medial region of the thigh, in a deep furrow, which is bounded anteriorly by the vastus medialis muscle, and posteriorly by the adductor muscles. If this furrow be traced proximally, it will be seen to run into the deeper, wider, and more apparent hollow, which has been described as the femoral triangle. Further, this intermuscular recess is converted into a canal, triangular on transverse section, by a strong fibrous membrane which stretches across it, and upon the surface of which the sartorius muscle is placed (Fig. 72). The tunnel VOL. i — 13 i94 INFERIOR EXTREMITY thus formed is called the adductor canal or " Hunter's Canal." When the fibrous expansion which closes in the canal is traced proximally, it is seen to become thin and ill-defined as it approaches the femoral triangle ; when traced in the opposite direction, however, it becomes dense and strong, and opposite the opening in the adductor magnus it presents a thick, sharply defined margin. It stretches from the adductor longus and the adductor magnus posteriorly to the vastus medialis anteriorly. In its distal part the posterior wall of the N. cutaneus femoris lateralis Femur M. vastus lateralis M. vastus intermedius M. biceps femoris M. semitendinosus M. rectus femoris Intermediate cutaneous nerve (O.T. middle) M. sartorius Femoral vessels in adductor canal (Hunter's) V. saphena magna M. adductor longus M. gracilis M. adductor magnu: M. semimembranosus FIG. 73. — Transverse Section through the Middle of the Thigh. The relationship of the parts in Adductor Canal (Hunter's) is seen. canal, where it is formed by the adductor magnus, presents a deficiency or aperture which leads backwards into the popli- teal fossa. The appearance and construction of this aperture will be studied at a later stage. It is called the hiatus tendineus or opening in the adductor magnus. The femoral vessels and the saphenous nerve traverse the adductor canal. In this part of its course the artery gives off some muscular twigs and the arteria genu suprema. The femoral vessels leave the canal at its distal end by inclin- ing posteriorly through the opening in the adductor magnus and entering the fossa poplitea. The saphenous nerve, accompanied by the saphenous branch of the art. genu THE THIGH 195 suprema, escape from the canal by passing under cover of the distal thickened margin of the fibrous expansion which forms the roof. They can be seen in the present stage of the dissection in this situation. Dissection. — The fibrous expansion which is stretched across the adductor canal, under cover of the sartorius muscle, should now be divided, in order that the arrangement of the parts within the canal may be studied. Distal Portion of the Femoral Artery. — The entire length of the femoral artery is now exposed. Below the apex of the femoral triangle it enters the adductor canal, and is separated from the medial surface of the thigh by the fibrous expansion which closes the canal, the sartorius muscle, the fascia lata, and the integument. The saphenous nerve crosses anterior to the artery from the lateral to the medial side. Proximo -distally the artery rests upon the pectineus, the adductor brevis, the adductor longus, and the adductor magnus. Its proximal part, however, is separated from these muscles by the femoral vein, which lies posterior to it ; more distally, the vein, which inclines laterally, comes to lie on its lateral side on a posterior plane. The relation of parts in the adductor canal is seen in Figs. 71, 72, and 73. From the femoral artery, as it traverses Hunter's canal, proceed muscular twigs and the arteria genu suprema. The muscular branches are irregular in number and in their mode of origin. They supply the vastus medialis, the adductor longus, and the sartorius. Arteria Genu Suprema (O.T. Anastomotic). — This branch springs from the femoral trunk a short distance proximal to the point where it enters the fossa poplitea by passing through the opening in the adductor magnus. The arteria genu suprema almost immediately divides into a saphenous and an articular branch : very frequently, indeed, these branches take separate origin from the femoral artery. The saphenous branch accompanies the saphenous nerve, and leaves the adductor canal by passing under cover of the distal border of the fibrous expansion which is stretched over the canal. On the medial side of the knee it appears between the gracilis and sartorius, and it ends in branches to the integument on the medial aspect of the proximal part of the leg. The articular branch enters the substance of the vastus 196 INFERIOR EXTREMITY medialis and proceeds distally, anterior to the tendon of the adductor magnus. It gives some twigs to the vastus medialis and others which spread out over the proximal and medial aspects of the knee-joint, and it anastomoses with branches of the medial genicular arteries. One well-marked branch runs laterally, proximal to the patella, to anastomose with the lateral superior genicular artery. Vena Femoralis (Femoral Vein). — This is the direct proximal continuation of the popliteal vein. It begins at the opening in the adductor magnus, through which it enters the adductor canal, whilst proximally it passes behind the inguinal ligament and becomes continuous with the external iliac vein. It accompanies the femoral artery, but the relations of the two vessels to each other differ at different stages of their course. In the distal part of Hunter's canal the vein lies on the lateral and posterior side of the artery, but it inclines medially as it ascends, and in the proximal part of the thigh it lies on its medial side and on the same plane. The cross- ing from one side to the other takes place posterior to the artery and is very gradual, so that for a considerable distance the femoral vein lies directly posterior to the femoral artery. For a distance of two inches distal to the inguinal ligament it is enclosed within the femoral sheath, of which it occupies the intermediate compartment. As it ascends in the thigh the femoral vein receives tributaries which, for the most part, correspond with the branches of the femoral artery. At the fossa ovalis it is joined by the great saphenous vein. The dissector should slit the femoral vein open with the scissors. Several valves will then be seen. One is almost invariably found immediately proximal to the entrance of the vein which corresponds to the profunda artery. Nervus Femoralis (O.T. Anterior Crural). — The femoral nerve is a large nerve which arises, within the abdomen, from the lumbar plexus. It enters the thigh by passing distally in the interval between the psoas and iliacus muscles, posterior to the inguinal ligament and the fascia iliaca. In the proximal part of the thigh it lies to the lateral side of the femoral artery, and is separated from it by a small portion of the psoas muscle and the femoral sheath. A short distance below the inguinal ligament it divides into an anterior and a posterior portion, which at once resolve themselves into a THE THIGH 197 large number of cutaneous and muscular branches. The following is a list of these : — ( T-, f To the pectineus. I Kami musculares, | sartorius. Anterior division, | Intermediate cutaneous. ( Kami cutanei anterior**, { Medkl cutaneous< ' To the rectus femoris. ,, vastus medialis. ,, vastus lateralis. Rami musculares, X ,, vastus inter- Posterior division, 1 medius. ,, m. articularis genu. Ramus cutaneus, Saphenous nerve. Rami articulares. With the exception of the saphenous nerve, which is distributed upon the medial side of the leg and foot, the distribution of the cutaneous branches of the femoral nerve has been already examined (p. 175). The nerve to the pectineus arises a short distance below the inguinal ligament and turns medially, posterior to the femoral vessels, to reach its destination. The branches to the sartorius are two or three in number. As a rule they take origin by a common trunk with the intermediate cutaneous nerve. The intermediate cutaneous nerve (O.T. middle cutaneous] sometimes pierces the proximal border of the sartorius. It divides into two branches which perforate the fascia lata about three or four inches distal to the inguinal ligament. The medial cutaneous nerve (O.T. internal cutaneous] inclines distally and medially and crosses anterior to the femoral artery. It divides into an anterior and a posterior portion, which become superficial at different levels on the medial side of the limb. From the trunk of the nerve a few cutaneous twigs are given to the skin over the proximal and medial parts of the thigh. The anterior branch crosses the sartorius muscle and makes its appearance through the fascia lata in the distal part of the thigh, a short distance in front of the great saphenous vein. The posterior branch runs distally, along the posterior border of the sartorius, and pierces the deep fascia on the medial side of the knee, behind the sartorius and the saphenous nerve. A short distance distal to the middle of the thigh the posterior branch of the medial cutaneous nerve forms, with filaments from the obturator nerve and the saphenous nerve, a plexiform interlacement, the sartorial plexus ; i— 13 a 198 INFERIOR EXTREMITY which is placed deep to the sartorius muscle as it lies over the adductor canal (Hunter's). The twig from the obturator nerve appears at the medial border of the adductor longus. The nervus saphenus (O.T. internal saphenous nerve] is the longest branch of the femoral nerve. It springs from the posterior division of that nerve and runs distally on the lateral side of the femoral artery. Entering the adductor canal, with the femoral vessels, it comes to lie anterior to the artery. At the distal end of the canal it emerges, by passing under cover of the thickened border of the fibrous expansion which stretches between the vastus medialis and the adductor muscles, and, accompanied by the saphenous branch of the arteria genu suprema, it escapes from under cover of the sartorius and pierces the deep fascia at the medial side of the knee. It gives off the infrapatellar branch after it quits the adductor canal. This branch pierces the sartorius and appears on the surface of the fascia lata on the medial side of the knee. Several large branches of the posterior part of the femoral nerve enter the four factors which compose the great quadriceps extensor muscle of the thigh. From certain of these, articular filaments are given to the hip and knee- joints. The branch to the rectus femoris sinks into the deep surface of that muscle. It supplies an articular twig to the hip-joint. The large branch to the vastus medialis accompanies the saphenous nerve and enters the proximal part of the adductor canal.' It can readily be distinguished from its sinking into the medial aspect of the vastus medialis about the middle of the thigh. In the substance of the muscle it extends distally, and near the knee joins the articular branch of the arteria genu suprema. It gives an articular nerve to the synovial lining of the knee-joint. The nerve to the vastus lateralis is associated with the descending branch of the lateral circumflex artery. Very frequently it gives an articular twig to the knee-joint. The nerves to the vastus intermedius are two or three in number and they sink into its anterior surface. The most medial of them is a long slender nerve, which can be traced distally under the anterior border of the vastus medialis to the articular muscle of the knee. Its terminal twigs are given to the synovial stratum of the knee-joint. One filament then from the femoral nerve goes to the THE THIGH 199 hip-joint ; two, and frequently three, filaments go to the knee-joint. Tractus Ilio-tibialis of Fascia Lata (O.T. Ilio-tibial Band). — The thick band of fascia lata on the lateral aspect of the thigh which receives this name should now be examined, and its connections ascertained. It has been preserved for this purpose. Distally it is attached to the lateral condyle of the tibia and to the head of the fibula. On tracing it proximally, on the lateral surface of the vastus lateralis, it will be observed to split, at the junction of the middle and proximal thirds of the thigh, into two lamellae — a superficial and a deep. The tensor fasciae latse is enclosed between these layers, and when they are disengaged from its surfaces the muscle will be seen to be inserted into the fascia at the angle of splitting. The superficial lamina of the tractus ilio-tibialis is attached above to the crest of the ilium, and is continuous posteriorly with the glutaeal aponeurosis where this covers the glutaeus medius. The deep lamina can be followed proximally, on the lateral surface of the rectus femoris, to the capsule of the hip-joint, with the upper and lateral part of which it blends. It is also connected with the reflected tendon of the rectus femoris. This layer is per- forated by the ascending twigs of the lateral circumflex artery of the thigh. M. Tensor Fasciae Latae (O.T. Tensor Fasciae Femoris). —This is a small muscle which is placed on the lateral and anterior aspect of the proximal third of the thigh. It lies between the two lamellae of the tractus ilio-tibialis, in the interval between the sartorius muscle anteriorly and the glutaeus medius muscle posteriorly. On turning the muscle laterally so as to display its deep surface, a little dissection will bring into view its nerve of supply which comes from the superior glutceal nerve. A few arterial twigs from the lateral circumflex artery also sink into its deep surface. The tensor fascice lata arises from a small portion of the anterior part of the lateral lip of the crest of the ilium ; from the upper part of the margin of the notch below the anterior superior (iliac) spine ; and by some fibres from the aponeurosis covering the glutaeus medius. It extends distally, with a slight inclination posteriorly, and is inserted into the tractus ilio-tibialis of the fascia lata at its angle of splitting. Art. Circumflexa Femoris Lateralis (O.T. External i—13 b 200 INFERIOR EXTREMITY Circumflex Artery). — This is the largest branch which proceeds from the profunda femoris artery. It arises near the origin of the latter from the femoral artery, and runs laterally, between the divisions of the femoral nerve and under cover of the sartorius and rectus femoris muscles. It ends by dividing into ascending, transverse, and descending branches. The ascending branch reaches the dorsum ilii by passing M. rectus femoris (straight head of origin) M. rectus femoris (reflected head of origin) Attachment of the lig. -ilio-femorale M. adductor longus (origin) M. pyramidalis abdominis (origin) . rectus abdominis (origin) M. semimem- branosus (origin) M. quadratus femoris (origin) Mm. biceps and semitendinosus (origin) M. gracilis (origin) M. adductor brevis (origin) FIG. 74.— Muscle- Attachments to the Lateral Surface of the Pubis and Ischium, proximally under cover of the tensor fasciae latae. Its terminal twigs anastomose with the superior glutaeal artery. The trans- verse branch is of small size. It passes to the deep surface of the vastus lateralis, reaches the posterior part of the thigh, and inosculates with the medial circumflex artery and the first perforating artery. The descending branch gives twigs to the vastus intermedius and rectus femoris, and one long branch, which may be traced distally, amid the fibres of the vastus lateralis, to the knee, where it anastomoses with the lateral superior genicular artery. THE THIGH 201 Intermuscular Septa. — Divide the tractus ilio-tibialis of the fascia lata distal to the point at which it splits to enclose the tensor fasciae latae. This is done so as to obtain a better view of the vastus lateralis, and in order to demonstrate satisfactorily the lateral intermuscular septum. Take hold of the distal portion of the tractus ilio-tibialis and draw it forcibly laterally ; at the same time push medially the vastus lateralis muscle, and a strong fibrous septum will be seen passing medially from the fascia lata towards the linea aspera. This is the lateral intermuscular septum of the thigh, a partition interposed between the vastus lateralis and the short head of the biceps femoris. Follow it proximally and distally with the finger. The fibres of the vastus lateralis are seen arising from it, but little difficulty will be experienced in making out its attach- ment to the linea aspera and lateral supracondylar ridge of the femur. It extends in a proximal direction as far as the insertion of the glutaeus maximus, whilst distally it reaches the lateral condyle of the femur. Immediately proximal to the lateral condyle of the femur it is pierced by the lateral superior genicular artery and nerve. The medial inter- muscular septum is interposed between the adductors and the vastus median's, and should also be examined. It is thin in comparison with the lateral septum. M. Quadriceps Femoris. — This muscle is composed of four portions. The rectus femoris, which is placed in the anterior part of the thigh, and is quite distinct from the others, except at its insertion ; the vastus lateralis, vastus inter- medius, and the vastus medialis, which clothe the body of the femur on its lateral, anterior, and medial aspects, and are more or less blended with each other. M. Rectus Femoris. — This muscle arises by two tendinous heads of origin, which may be exposed by dissecting deeply in the interval between the iliacus and tensor fasciae latae. The anterior or straight head springs from the anterior inferior spine of the ilium (Fig. 74, p. 200); the posterior or reflected head arises, under cover of the glutaeus minimus, from a marked impression on the lateral surface of the ilium, immediately above the upper part of the rim of the acetabulum (Fig. 74, p. 200). It is connected both with the capsule of the hip- joint and the deep lamina of the ilio-tibial tract of the fascia lata. At the present stage of dissection it is only possible to display the 202 INFERIOR EXTREMITY M. obturator internus M. piriformis anterior part of this head ; the posterior part will be seen in the dissection of the glutreal region. The two heads of origin of the rectus femoris join at a right angle, immediately beyond the margin of the acetabulum, and form a strong flattened tendon, which gives place to a fusiform, fleshy belly. The tendon of origin spreads out on the anterior surface of the proximal part of the muscle in the form of an aponeurosis. About three inches proximal to the knee-joint the rectus femoris ends in a strong tendon of insertion, which is prolonged for some distance proximally, on its deep surface, in the form of an aponeurosis. As it nears the patella this tendon is joined by the other tendons of the quadriceps, and through the medium of a com- mon tendon finds insertion into the proximal border of that bone. The rectus femoris is supplied by the femoral nerve. M. Vastus Lateralis (O.T. FIG. 75. — Anterior Aspect of Proximal Vastus ExternUS) forms the Portion of Femur with Attachments inent muscular mass On of Muscles mapped out. the lateral side of the thigh. Its surface is covered by a glistening aponeurosis. The descending branch of the lateral circumflex artery constitutes the best guide to its anterior border, and when this margin is raised it will be seen that the muscle lies upon, and is partially blended with, the vastus intermedius. The vastus lateralis arises — (i) from the proximal part of the linea intertrochanterica ; (2) from the front of the trochanter major, distal to the insertion of the glutaeus minimus ; (3) from the root of the trochanter major below the insertion of the glutaeus medius ; (4) from the lateral part of the glutaeal tuberosity anterior to the insertion of the glutaeus M. ilio-psoas THE THIGH 203 maximus ; (5) from the proximal part of the linea aspera ; and (6) from the lateral intermuscular septum. The fleshy fibres are for the most part directed distally and anteriorly. By means of the common tendon of insertion the muscle gains attachment to the patella and, at the same time, gives an expansion to the capsule of the knee-joint. It is supplied by the femoral nerve. M. Vastus Medialis (O.T. Vastus Interims) is intimately connected with the vastus intermedius, but not to such an extent as might be inferred from a superficial inspection. In its proximal part the anterior border, which is fleshy, is either contiguous to or blended with the intermedius ; distally, the anterior border is tendinous and overlaps the intermedius, but it is not, as a rule, fused with it. "A line drawn from the middle of the linea intertrochanterica distally and slightly laterally to the middle of the proximal border of the patella will define accurately the thick anterior border of the vastus medialis. " — (Williams. ) Dissection. — Divide the rectus femoris about its middle, and pull the distal part forcibly towards the foot. The narrow interval between the tendons of the vastus intermedius and vastus medialis will then become apparent, and may be followed proximally. A still further guide is the long, slender nerve of supply to the articular muscle of the knee ; it runs along the medial edge of the vastus intermedius. When the anterior border of the vastus medialis is raised from the vastus intermedius the medial surface of the body of the femur will be seen to be perfectly bare. No muscular fibres arise from this bony surface. The fleshy mass of the vastus medialis may now, with advantage, be divided transversely about two inches proximal to the patella. The muscle can then be thrown medially, and its origin studied. The vastus medialis arises — (i) from the lower part of the linea intertrochanterica; (2) from the line leading from this, distal to the trochanter minor, to the linea aspera ; (3) from the medial lip of the linea aspera ; (4) from the proximal part of the medial supracondylar line as far distally as the opening in the adductor magnus; (5) from the rounded tendon of the adductor magnus. The fleshy fibres are directed distally and anteriorly, and end in the common tendon of the quadri- ceps muscle. By this it is inserted into the patella, and becomes connected with the capsule of the knee-joint. It is supplied by the femoral nerve. M. Vastus Intermedius (O.T. Crureus) covers the anterior and lateral aspects of the body of the femur, from both of which, as well as from the distal part of the lateral inter- 204 INFERIOR EXTREMITY muscular septum, it takes origin. It is inserted into the patella through the medium of the common tendon. It is supplied by the femoral nerve. Common Tendon of the Quadriceps. — It should now be noticed that the common tendon of the quadriceps muscle closes the knee-joint above the patella. It is inserted into the proximal border of that bone, and is intimately connected with the capsule of the knee-joint. Some fibres are carried distally into the ligamentum patellae upon the surface of the patella. A pouch of synovial membrane is prolonged proximally beyond the level of the patella, between the quadriceps and the bone. Into the wall of this pouch the m. articularis genu is inserted. Dissection. — The vastus intermedius should be divided in a vertical direc- tion, so as to bring the little muscle articularis into view, and at the same time the long, slender nerve-filament which runs along the medial border of the vastus intermedius may be traced to the muscle and the synovial stratum of the knee-joint. The ligamentum patella, which connects the patella with the tuberosity of the tibia, and through which the quadri- ceps is attached to that bone, will be studied in connection with the knee-joint. The whole of the quadriceps femoris is an extensor of the knee, and the rectus portion is also a flexor of the hip-joint. MEDIAL SIDE OF THE THIGH. The group of adductor muscles on the medial aspect of the thigh, together with the blood-vessels and nerves associated with them, must next be dissected. In this dissection the following are the structures which are displayed :— ( Pectineus. Adductor longus. Miisrlps J Adductor brevis. Muscles, < Adductor magnus. Gracilis. V Obturator externus. ... f Profunda femoris (and its branches). Arteries, {Obturator. ^ ' / The two divisions of the obturator nerve, rves, \Occasionally the accessory obturator nerve. MEDIAL SIDE OF THE THIGH 205 The adductor muscles are disposed in three strata. The anterior stratum is formed by the adductor longus and the pectineus, which lie in the same plane. Proximally they are placed side by side, but distally, as they approach their in- sertions, they are separated from each other by a narrow interval. The second stratum is formed by the adductor brevis ; and the third, or posterior layer, by the adductor magnus. The gracilis muscle, also an adductor, extends along the medial aspect of the thigh. It is a long, strap-like muscle, applied against the adductor brevis and adductor magnus. Inter- posed between these muscular layers, are the two divisions of the obturator nerve. The anterior division is placed between the anterior and middle layers, whilst the posterior division lies between the middle arid posterior layers. In other words, the two divisions of the nerve are separated from each other by the adductor brevis, which intervenes between them. At the distal border of the adductor longus, a fine branch from the anterior division of the nerve makes its appearance to take part in the formation of the sartorial nerve plexus already dissected. The profunda artery and its branches are also to be followed. For a part of its course this vessel is placed between the anterior and middle muscular strata. M. Adductor Longus. — This muscle is placed on the medial side of the pectineus. It is somewhat triangular in shape, being narrow at its origin and expanded at its in- sertion. It arises by a short, but strong, tendon from the anterior surface of the body of the pubis, immediately distal to the pubic ridge (Fig. 74, p. 200), and it is inserted into the medial lip of the linea aspera of the femur by a thin, tendinous expansion. It is supplied by the anterior division of the obturator nerve. Dissection. — The adductor longus may now be reflected. Divide it close to the tendon of origin, and throw it laterally. In doing this be careful of the anterior division of the obturator nerve, which lies posterior to it, and gives to it its nerve of supply. On approaching the linea aspera of the femur its aponeurotic tendon will be found intimately connected with the vastus medialis anteriorly and with the adductor magnus posteriorly. Separate it from these as far as possible, in order that the profunda femoris vessels may be fully displayed as they proceed behind it. Art. Profunda Femoris. — This large vessel is the chief artery of supply to the muscles of the thigh. It arises in the femoral triangle from the lateral and posterior aspect of the femoral artery, about an inch and a half distal to the inguinal 206 INFERIOR EXTREMITY ligament. At first it is placed on the iliacus, but, as it pro- ceeds distally, it inclines medially and thus it crosses posterior to the femoral artery, and conies to lie on the pectineus. Reaching the proximal border of the adductor longus, it passes posterior to that muscle, and is continued distally, close to the body of the femur, in front of the adductor brevis and adductor magnus. Numerous large branches spring from the profunda M. rectus femoris (straight head of origin) M. rectus femoris (reflected head of origin) Attachment of the lig. ilio-femorale M. adductor longus (origin) M. pyramidalis abdominis (origii M. rectus abdominis (origin M. semimem- branosus (origin) M. quadratus femoris (origin) Mm. biceps and semitendinosus (origin) M gracilis (origin) M. adductor brevis (origin) FIG. 76. — Muscle-Attachments to the Lateral Surface of the Os Pubis and Os Ischium. femoris, so that it rapidly diminishes in size. Ultimately it is reduced to a fine terminal twig, which turns posteriorly through the adductor magnus, and receives the name of the fourth perforating artery. The following are the relations of the profunda femoris: — (i) It lies anterior to the iliacus to the lateral side of the femoral artery. (2) It is anterior to the pectineus and posterior to the femoral artery, but separated from it by the femoral vein and the profunda vein. (3) It is anterior to the adductor brevis, and lower down to the adductor magnus and posterior to the adductor MEDIAL SIDE OF THE THIGH 207 Obturator externus longus, which separates it from the femoral artery. (4) The terminal twig, called the fourth perforating artery, pierces the adductor magnus at the junction of the middle and distal thirds of the thigh. The branches which spring from the profunda femoris are : — the two circumflex arteries, the four perforating arteries, and some muscular branches. The lateral cir- cumflex artery arises from the lateral as- pect of the profunda, close to its origin. It has already been followed to its dis- tribution (p. 198). The medial circumflex artery, which takes 3rd rami per- . . forantes origin at the same level, but from the medial and posterior aspect of the pro- funda, will be studied when the pectineus muscle is reflected. The muscular branches are irregular both in origin and size. They supply the adductor muscles, and give twigs which pierce the adductor magnus to reach the ham- string muscles. The medial cir- cumflex artery frequently arises from the femoral trunk. Arterise Perforantes (Perforating Arteries). — These arise in series from the main trunk, and pass posteriorly through the adductor muscles to the posterior region of the thigh. They may be recognised from the close relation which they bear to the linea aspera of the femur. The arteria perforans prima comes off at the level of the distal border of the A. femoralis Opening in adductor magnus Art. genu suprema (O.T. anastomotic) Femoral artery FIG. 77. — A. Profunda Femoris and its Rami. 208 INFERIOR EXTREMITY pectineus. It proceeds posteriorly through the adductor brevis and adductor magnus. The arteria perforans secunda takes origin a short distance lower down, or perhaps by a common trunk with the first perforating. It pierces the same muscles, viz. the adductor brevis and adductor magnus. The arteria perforans tertia springs from the profunda distal to the adductor brevis, and passes posteriorly through the adductor magnus. The arteria perforans quarta, as before noted, is the terminal branch of the profunda femoris ; it pierces the adductor magnus alone. The arteria nutricia femoris superior may spring from either the second or the third perforating branch. An inferior nutrient artery is frequently present ; it is often derived from the fourth perforating artery. When the adductor magnus is more fully exposed it will be seen that the perforating arteries, as they pierce its tendon, have a series of fibrous arches thrown over them. M. Pectineus. — This muscle is placed between the adductor longus and the ilio-psoas. It is flat and somewhat broader at its origin from the brim of the pelvis than at its insertion into the femur. It has a fleshy origin, from the pecten pubis, and from the surface of the innominate bone anterior to it (Fig. 74, p. 200). Some fibres are likewise derived from the lacunar ligament. It descends obliquely laterally and posteriorly, and gains insertion into the femur, posterior to the lesser trochanter, and to a certain extent also into the line which leads from that prominence down to the linea aspera. It is supplied by the femoral nerve. Dissection. — The pectineus may be detached from its origin, and thrown distal ly and laterally. In separating the muscle from the pubis the dis- sector must bear in mind that in some cases an accessory obturator nerve descends into the thigh, under cover of its lateral margin, and over the brim of the pelvis. Care must also be taken not to injure the anterior division of the obturator nerve which lies posterior to the muscle, or the medial circumflex artery which passes posteriorly in contact with its lateral border. The Nervus Obturatorius Accessorius when present arises within the abdomen from the lumbar plexus or from (Fig. 208) the obturator trunk near its origin. In the thigh it gives a branch to the hip-joint and joins the anterior division of the obturator nerve. It is very rare to find a twig given to the pectineus either by it or by the trunk of the obturator nerve itself. Art. Circumflexa Femoris Medialis (O.T. Internal Circum- flex)— This vessel springs from the medial and posterior aspect of the profunda femoris artery at the same level as the lateral MEDIAL SIDE OF THE THIGH 209 circumflex branch. It passes posteriorly between the adjacent margins of the psoas and the pectineus, and then between the adductor brevis and the obturator externus, the posterior region M. obturator externus M. obturator internus M. quadratus femoris to Of the thigh where, close to the lesser trochanter, it divides into an ascend- ing and a transverse terminal branch. Before it divides the main trunk gives off (i) a super- ficial branch which passes medially across the front of the pectineus and between the ad- ductors longus and brevis, and (2) an arti- cular branch which enters the hip -joint through the incisura acetabuli. The terminal branches will be examined in the dissection of the gluteal region. Branches of the Femoral FlG- 78. — Posterior aspect of Proximal Artery- -In every region of Portion of Femur with the Attachments the thigh the dissector has met of Muscles mapped out. with branches of the femoral artery. It is well now that he should revert to this vessel and study its branches in the order in which they arise. The following Table may aid him in doing this : — Aa. pudendse externae (superficial and deep). "1 g r£ ja} A. epigastrica superficial ^ £guina1. A. circumnexa ilium superhcialis. j f A. circumflexa femoris lateralis. j A. circumflexa femoris medialis. A. perforans prima. A. perforans secundus. •{ Aa. Nutricire. A. perforans tertia. A. perforans quarta (terminal). A. femoralis. - A. profunda. Kami Musculares. A. genu suprema. M. Adductor Brevis. — This muscle lies posterior to the adductor longus and the pectineus. It arises, distal to the VOL. i — 14 210 INFERIOR EXTREMITY origin of the adductor longus, from the anterior aspect of the body and the inferior ramus of the os pubis (Fig. 74, p. 200). As it descends it inclines posteriorly and laterally, and it is Anterior superior spine of ilium Tensor fasciae latse Iliacus Psoas External iliac vessels Femoral nerve (O.T. anterior crural) Capsule of hip-joint, grooved by m. ilio-psoas Pect;neus Profunda femoris vessels Vastus lateral is Vastus intermedius Rectus femoris Saphenous nerve Sartorius FIG. 79. — Dissection of the Front of the Thigh. The hip-joint has been exposed by removing portions of the muscles which lie anterior to it. inserted, posterior to the pectineus, into the whole length of the line which extends from the lesser trochanter to the linea aspera (Fig. 78, p. 209). It is supplied by the obturatornerve. Dissection. — Reflect the adductor brevis by cutting it close to its origin, and throwing it distally and laterally. The posterior division of the MEDIAL SIDE OF THE THIGH 211 obturator nerve is then exposed, and should be traced proximally to the obturator foramen, and distally to its distribution upon the adductor magnus. Nervus Obturatorius (Obturator Nerve). — The obturator nerve is a branch of the lumbar plexus (Fig. 212). It escapes Ace. Obturator nerve. Obt. Obturator nerve. O.I. Obturator internus. O.E. Obturator externus Py. Piriformis muscle. G.Ma. Glutaeus maximus. Q. Quadratus femoris. A.M. Adductor magnus. P. Pectineus. A.B. Adductor brevis A.L. Adductor longus. G. Gracilis. X . Branch to hip-joint. I.C. Medial circumflex artery. 1. Cutaneous branch. 2. Twig to walls of femoral artery. 3. Branch to knee- joint. FIG. 80. — Diagram to illustrate the distribution of the Obturator Nerve and the general disposition of the Adductor Muscles of the Thigh (Paterson). from the pelvis by passing, with its companion vessels, through the upper part of the obturator foramen of the innominate bone. While still within the foramen it divides into an anterior and a posterior division. The anterior division of the obturator nerve enters the thigh over the upper border of the obturator externus muscle, and proceeds distally upon the anterior surface of the adductor 212 INFERIOR EXTREMITY brevis. Anterior to it are the pectineus and adductor longus muscles. It gives branches to three muscles, viz. the adductor longus, the adductor brevis, and the gracilis. Very rarely it will be observed to supply a twig to the pectineus. In addi- tion to these it supplies an articular branch to the hip-joint (Fig. 80, x ) • a fine twig, which appears at the distal border of Femoral nerve (O.T. ant. crural) Lumbo-inguinal nerve Femoral sheath \ Femoral canal '.