•;A-r•-';•.•:t?.",w • ■■.■-•.•'.**»'. ~j, .-.-'■ ^■f; Wv *> • .'•■-.;-.,-^-i ■ •■V$5jfei Jk r ^^COO'J'O^O- -*?. Surgeon General's Office ejection,-- *e& AN INTRODUCTION TO THE STUDY OF HUMAN ANATOMY. BY JAMES PAXTON, MEMBER OF THE ROYAL COLLEGE OF SURGEONS, HONORARY MEMBER OF THE ASHMOLEAN SOCIETY, AND AUTHOR OF THE NOTES AND ILLUSTRATIONS OF PALEY's NATURAL THEOLOGY. WITH ILLUSTRATIONS. FIRST AMERICAN EDITIPN, WITII ADEflTrONS. BY WINSLOW LEWIS, JUN. M.D. DEMONSTRATOR OF ANATOMY TO THE MEDICAL DEPARTMENT OF HAR- ^TARD UNIVERSITY.t-j ..iiiiv ' > v <-• r • , ' I i BOSTON: CARfM' AND HENDEE. * < • » ,.. MDCCC XXXII. //?2 4 QS ,•■ KNGKAVF.D AND PRIN TF.D >T CART!*, ANDRRWS, AND CO. • LANCASTER. MASS. PREFACE OF THE AMERICAN EDITOR. The evident utility of the anatomical work of Paxton, founded on the union of graphic and ex- planatory designs, must at once be apparent to those, who, without such a guide, have experienced great difficulties in conceiving of the appearances of parts from verbal description alone. The only work on Anatomy re-published in this country, accompanied with plates, is that of Charles and John Bell, which are expensive, without being well done, and the student is obliged to turn from the book of the text to that of the plates. In these volumes of Paxton, at a moderate cost, this is obviated. The reader has, at a coup S? ceil, the representation of the part before him, with a sim- ple explanation. This work only claims to be of an elementary character, and one to be studied at the very commencement of professional reading: to serve to introduce the student to those more elaborate and excellent systems, with which our own anatomists have enriched this department- iv preface. Those of Wistar and of Horner are works which may honour any country. The American Editor of Paxton has made, he trusts, some useful additions, which he has prefer- red rather to embody with the work, than to dis- figure it, by placing them as notes. Its mechanical excellence will at least bear proof of the skill of the artists. W. L. Jun. PREFACE TO THE ENGLISH EDITION. The present work contains a concise and clear demonstration of the structure of the human body ; and on this it grounds its claim to the notice of the professional and the scientific reader. It is admitted that a much larger store of anatomical knowledge is contained in the works of Fyfe, Bell, Lizars, and others, as well as in the splen- did publications of continental authors ; but no one has given to the public a treatise in its present form, containing graphic and descriptive anatomy on the same page. The principal object of the present undertaking is, to furnish the student with sufficient directions for cultivating this particular department of science, in the shortest and most successful manner; and for this purpose the author has endeavoured to give a correct drawing, as well as an exact description of the parts, by which the mind will be assisted in forming its conceptions, and the memory in retaining or recalling past vj PREFACE. impressions, when the dissections are imperfectly remembered, or cannot be repeated. Those who are familiar with the admirable work of J. Cloquet, Anatomie de PHomme, will perceive that frequent use has been made of it, both in figures and description. Much interest has of late been excited by pub- lications which display the mechanism of nature ; indeed, the utility and application of animal me- chanics, in several branches of science beside those of medicine and surgery, have been frequently pointed out. From the structure and functions of living bodies, writers on Natural Theology find ample materials for showing design and goodness in the creation ; and certainly no ground of argu- ment could be better chosen, or afford more strik- ing illustrations of the wisdom and power of the Creator, than the anatomy of man; which, through- out, is but the history of means adapted to certain ends. Those only who study the structure of animated nature, can estimate and admire as they ought the wonderful contrivances of the human frame. " It is evident, therefore, that, the more correctly a divine is informed respecting anatomy and physiology, the more effectually will he be enabled to employ his knowledge as an argument PREFACE. yJJ in favour of natural religion51." And, as a branch of general education also, it deserves the attention of all those concerned in the instruction of youth. It is acknowledged by most persons, that natural history cannot be advantageously studied unless we are acquainted with the structure of the objects of our research, or with comparative anatomy, so called from its comparing the anatomy of other living creatures with that of man. So, also, the science of geology, which in the present age so much engages the attention of philosophic inquiry, receives great elucidation from the anatomical character of animals. Natural philosophy has derived aid from the investigation of the human structure, particularly from a knowledge of the formation of the eye and the ear; for " the eye is an organ or instrument by which vision is performed : it is by its nature the most perfect optical instrument, and the foun- dation of all other■sV The provisions in the eyes of different animals for regulating the admission of light, the adapta- tion of their refracting powers to the different me- dia, and the momentary changes in their forms for the vision of near or distant objects, are some of a Dr. Macartney. b Emerson. the most interesting points of physiology, and evi- dently connected with the science of optics. The organ of hearing may be said to be com- pletely artificial, differing in different animals ac- cording to the circumstances in which the function is to be exercised. All these varietes are founded on the general laws for the transmission of sound through various vibrating substances ; those laws, therefore, cannot fail to derive elucidation from a knowledge of the mechanism of the ear. In the fine arts, sculpture and painting receive considerable assistance from a knowledge of ana- tomy. Without some acquaintance with this sci- ence, the artist cannot determine the correctness of his figures; for the bones give the form and the proportion of the joints, and the muscles the inter- vening outline. The various emotions of the mind naturally call into action certain muscles ; and the predominating passion stamps upon the counte- nance a corresponding indelible impression, though the mind may not be at every instant under its influence. The representation of muscular actions constitutes the anatomy of expression ; so that the success of the historical painter must very much depend on his knowing the separate and combined action of the moving powers, in the various atti- tudes and positions of the human body; for not PREFACE. Jx only the face, but every other part of the person, participates in the mental emotion, and more or less influences the contour and general character of the figure. Many of the ancient statues, as the Lacoon, the Gladiator, and others, display a stu- died observation and a correct expression of mus- cular motion. As a branch of general education, anatomy and physiology are subservient to several other objects. For instance—in many judicial inquiries ; in the examination of legal evidence ; in the regulation and infliction of punishments ; and in the conside- ration of the best modes of coercion, or the re- straints which are most effectual in preventing crime;—the powers of the human constitution should be accurately considered. I have taken a cursory view of some of the col- lateral advantages which may accrue from the study of anatomy and physiology; but to the student in medicine, these sciences must be considered indis- pensable. Not only is it his duty, before entering into practice, to obtain the most perfect knowledge of this department of his profession, by studying the structure and functions of animal bodies, but he must carefully, during the whole course of his professional career, keep up his stock of informa- tion. On the importance of anatomical science, b x PREFACE. the late Dr. Baillie has thus expressed himself: " There is not a physician, or surgeon, who can conscientiously discharge his duty to his patient or to himself, who does not occasionally, I ought to say, who does not frequently, inspect the human frame; a knowledge of which is the very foundation of medical science, and a guide to us in the distri- bution of life and health to our fellow-creatures." From an acquaintance with the structure and functions of the several parts of the human body when in health, we are able, for the most part, to judge of its state when under deviations occasioned by disease, and thus to act upon just and rational principles in our treatment of the innumerable de- rangements to which our frame is liable. It is in the pages of death that we read the history of life —it is by taking to pieces the machine that we discover some at least of the wheels which put it in motion : for the same reason we are obliged to examine the body by dissection, before we can ex- plain its constitution and actions. The anatomist, therefore, first studies the apparently simple ele- ments which compose our complex fabric, examin* ing successively all those solid pieces of framework which give to the body its proportions, permit or limit its movements ; that by separating the levers of the system, he may be better able to observe PREFACE. XJ their junctures, and the fastenings which retained them in their situation. Next he traces out the moving powers which act on them and direct them, or which enable the animated form to execute the external and internal actions necessary to exist- ence. He then dissects the principal tubes which distribute that vital and regenerating fluid, which repairs the waste of material, by supplying an ac- cession of substance to the complicated machine. Afterwards he investigates those organs which communicate sensation, and transmit, swifter than lightning, the orders of the will, by means of those delicate fibres which establish such intimate rela- tions between us and the bodies with which we are surrounded. Lastly, he analyses those optical, acoustic, and chemical instruments of nature, which produce sensations ; and contemplates, in their defunct state, those organs which, under a living principle, exercised a series of functions, excelling each other in the wonder they excite, and follow- ing one another in such intimate succession, as gives them the appearance of being connected to- gether by an invisible but most admirable chain. CONTENTS. CHAP. I. PAGK Of the bones in general, or osseous SYSTEM 1 Ossification 2 Eminences and depressions of bones 3 Forms of bones 5 Colour of bones 6 Texture of bones . 7 Periosteum 8 Composition of bones 9 Table of the bones 10,11 A front view of the male skeleton 13 A back view of the male skeleton 14 CHAP. II. Bones of the head 15 The sutures 16 The frontal bone. Os frontis 18 The parietal bones. Ossa parietalia 20 The occipital bone. Os occipitis 21 The temporal bones. Ossa temporum . 23 The sphenoid bone. Os sphenoides 26 The ethmoid bone. Os ethmoides 28 The Wormian, or triangular bones. Ossa Wormi ana, ossa triquetra 29 XIV CONTENTS. The bones of the face The nasal bones. Ossa nasi The lachrymal bones. Ossa lachrymalia The cheek bones. Ossa malarum The upper jaw bones. Ossa maxillaria superiora The palatine bones. Ossa palatina The turbinated bones. Ossa turbinata The vomer The lower jaw. Os maxillare inferius . CHAP. III. The bones of the trunk The vertebrae of the neck The peculiarities of the vertebrae of the The first vertebra or atlas The second vertebra or dentata The seventh vertebra of the neck The vertebras of the back The vertebrae of the loins General observations on the spine The ribs. Costa . * . The first rib The eleventh and twelfth ribs The breast bone The bones of the pelvis The unnamed bones. Ossa innominata The os sacrum The coccyx. Os coccygis neck CHAP. III.* The bones of the upper extremity The collar bone. Clavicula . * This chapter should, in the text, have been headed Chap. IV. Th observed in the English edition, until too late to rectify it in tins. CONTENTS. XV The shoulder blade. Scapula The upper arm bone. Os brachii The bones of the fore arm The ulna or larger bone of the fore arm The radius The bones of the hand The bones of the wrist. Carpus The bones of the palm of the hand. Metacarpus The bones of the fingers. Phalanges digitorum The bones of the thumb 53 56 57 58 59 60 ib. 62 63 64 CHAP. IV. The bones of the lower extremity The thigh bone. Os femoris The knee pan. Patella The shin bone. Tibia The splint bone. Fibula The bones of the foot The bones of the tarsus The astragalus The heel bone. Os calcis The scaphoid, or navicular bone The cuneiform bones The inner cuneiform bone The middle cuneiform bone . The outer cuneiform bone The cuboid bone. Os cuboides The metatarsal bones The bones of the toes The sesamoid bones The tongue bone. Os hyoides 65 ib. 68 69 70 71 ib. 72 ib. 73 ib. 74 ib. 75 ib. 76 77 ib. 78 CHAP. V. The teeth • ... 79 The structure of the teeth . . . ib. xvi CONTENTS. The enamel of the teeth The osseous substance of the teeth The classes of teeth The incisors The canine teeth The grinders Of the formation of the teeth . Of the deciduous teeth Of the permanent teeth CHAP. VI. The medullary system, or marrow of bones ART. II. CHAP. I. Cartilaginous system, or the gristle of bones, etc. ART. III. CHAP. I. Fibrous system CHAP. II. Perichondrium CONTENTS. CHAP. III. The ligaments Capsular ligaments Lateral ligaments Ligaments within the joints . CHAP. IV. PARTICULAR LIGAMENTS. Ligaments of the head Ligaments of the lower jaw Capsular ligament . Interarticular cartilage Internal lateral ligament Stylo-maxillary ligament External lateral ligament Ligaments connecting the head and neck Two capsular ligaments Anterior perpendicular ligament Posterior perpendicular ligament Two lateral ligaments CHAP. V. Ligaments of the vertebra Ligaments of the second vertebra Transverse ligament Ligaments common to all the vertebrae . Anterior common ligament Posterior common ligament . Intervertebral ligament Ligamenta subflava Interspinous ligaments Supraspinous ligaments Ligaments of the oblique process c xviii CONTENTS. CHAP. VI. LIGAMENTS OF THE THORAX. LIGAMENTS OF THE RIBS WITH THE VERTEBRA. Capsular ligaments Interarticular ligament Middle transverse ligament . Inferior transverse ligament . Anterior or radiated ligament Ligaments of the cartilages of the ribs with the sternum 104 ib. 105 ib. ib. 106 CHAP. VII. Ligaments of the pelvis Long posterior ligament of the ilium Short posterior ligament Posterior lateral ligament Great sacro-sciatic ligament Smaller sacro-sciatic ligament Superior ilio-lumbar ligament Inferior ilio-lumbar ligament Ilio-sacral ligaments Symphysis of the ossa pubis . Membrane of the thyroid foramen Ligament of Fallopius or Poupart 107 ib. ib. 108 ib. 109 ib. ib. 110 ib. ib. ib. CHAP. VIII. Ligaments of the superior extremities Ligaments of the clavicle Interclavicular ligament Sterno-clavicular ligament Interarticular cartilage 111 ib. ib. 112 ib. CONTENTS. Costo-clavicular ligament Acromioclavicular ligament . Coraco-clavicular ligament Ligament of the scapula. Acromio-coracoid ligament Coracoid igament .... Ligaments between the scapula and humerus. Cap- sular ligament .... Accessory ligament Ligaments between the humerus and bones of the arm. Capsular ligament External lateral ligament Internal lateral ligament Ligaments between the radius and ulna. Superior articulation. Orbicular ligament Anterior and posterior accessory ligaments Middle articulation. Round ligament. Chorda transversalis cubiti Interosseous ligament Inferior articulation. Interarticular cartilage. Car- tilago intermedia triangularis Capsular or sacciform ligament External lateral ligament Internal lateral ligament Ligaments of the carpus Ligaments of the first row of the carpal bones Ligaments of the second row of the carpal bones . Ligaments of the two rows of carpal bones The annular ligament of the carpus Ligaments of the hand Capsular ligaments .... Superior transverse ligaments Inferior transverse ligaments . Ligaments of the fingers . CHAP. IX. Ligaments of the lower extremity Ilio • femoral ligaments XX CONTENTS. Cotyloid ligament . Capsular ligament . Interarticular ligament. Ligamentum teres Ligaments of the knee joint Capsular ligament . Lateral ligaments , External lateral ligament Internal lateral ligament Crucial ligaments . Anterior crucial ligament Posterior crucial ligament Interarticular or semilunar cartilage Ligaments between the tibia and fibula . Capsular ligament . Interosseous ligament Ligaments of the lower end of the tibia and fibula Ligaments of the ankle-joint . Ligaments between the fibula and tarsus Ligaments between the tibia and tarsus Deltoid or tibio-tarsal ligament Capsular ligament .... Ligaments of the tarsus Ligaments between the os calcis and astragalus Ligaments between the astragalus and os naviculare Ligaments between the os calcis and naviculare Ligaments between the os calcis and os cuboides . Ligaments between the navicular and cuboid bones Ligaments between the navicular and cuneiform bones .... Ligaments between the cuneiform bones Ligaments between the cuboid and external cunei- form bones .... Ligaments of the tarsus with the metatarsus Ligaments of the metatarsal bones with each other Ligaments of the metatarsus with the phalanges of the toes Ligaments of the phalanges of the toes . CONTENTS. XXI ART. IV. CHAP. I. Muscular system Form of the muscles The long muscles . The wide muscles . The short muscles . Voluntary, involuntary, and mixed muscles Texture of muscles Cellular tissue of muscles Blood-vessels of muscles Nerves of muscles . Tendons of muscles Aponeuroses Chemical composition of muscles Sheaths of tendons . Strength of muscles Actions of muscles . Nomenclature of the muscles Classification of the muscles . CHAP. II. Table of the muscles Muscles of the head ----- of the face . ----- of the neck ----- of the trunk ----- of the abdomen ----- of the posterior part of the trunk ----- of the extremities ----- of the superior extremities ----- of the shoulder ----- of the arm . xxii CONTENTS. Muscles of the fore arm ------- of the hand ------- of the inferior extremity ------- of the haunch and thigh -------■ of the leg . ——— of the foot . ------- of the head. Cranial Occipito-frontalis Auricular region Attollens auris Aitrahens auris Retrahens auris Muscles of the face Palpebral region Orbicularis palpebrarum Corrugator supercilii Levator palpebras superioris Ocular region Rectus superior Rectus inferior Rectus internus Rectus externus Obliquus superior . Obliquus inferior Nasal region Pyramidalis nasi Compressor nasi Levator labii superioris alasqu Depressor alae nasi . Superior maxillary region Levator labii superioris Levator anguli oris Zygomaticus major Zygomaticus minor Orbicularis oris Inferior maxillary region Depressor anguli oris Depressor labii inferioris Buccinator CONTENTS. xxiii Levator menti Masseter Temporo-maxillary region Temporalis Pterygo-maxillary region Pterygoideus externus Pterygoideus internus Lingual region Hyo-glossus Genio-glossus Stylo-glossus Lingualis Palatine region Circumflexus palati Levator palati Levator uvulae Palato-pharyngeus . Constrictor isthmi faucium CHAP. III. Muscles of the neck Anterior cervical region Platysma myoides Sterno-cleido mastoideus Digastricus Stylo-hyoideus Mylo-hyoideus Genio-hyoideus Inferior hyoid region Omo-hyoideus Sterno-hyoideus Sterno-thyroideus Thyro-hyoideus Pharyngeal region Constrictor pharyngeus inferior Constrictor pharyngeus medius Constrictor pharyngeus superior xxiv CONTENTS. Stylo-pharyngeus Deep cervical region Rectus capitis anticus major Rectus capitis anticus minor Longus colli Lateral cervical region Scalenus anticus Scalenus posticus . Rectus capitis lateralis CHAP. IV. Muscles of the trunk Anterior thoracic region Pectoralis major Pectoralis minor Subclavius Lateral thoracic region Serratus magnus Intercostal region Intercostales externi Intercostales interni Levatores costarum Triangularis sterni . Region of the diaphragm Diaphragma Muscles of the abdomen Abdominal region . Obliquus abdominis externus Obliquus abdominis internus Transversalis abdominis Rectus abdominis . Pyramidalis Lumbar region Psoas magnus Psoas parvus Uiacus internus Quadratus lumborum CONTENTS. XXV Anal region Levator ani Coccygeus Sphincter ani Genital region in the male Crem aster Ischio-cavernosus . Bulbo-cavernosus Ttansversus perinei Genital region in the female Ischio-cavernosus . Constrictor vaginae . Muscles of the posterior part of the trunk Lumbo-dorsal region Trapezius Latissimus dorsi Dorso-cervical region Rhomboideus Levator scapulae Serratus posticus superior Serratus posticus inferior Splenius . Complexus Trachelo-mastoideus Posterior occipito-cervical region Rectus capitis posticus major Rectus capitis posticus minor Obliquus capitis superior Obliquus capitis inferior Interspinales cervicis Vertebral region Longissimus dorsi Sacro-lumbalis Transversalis colli Multifidus spinae Intertransversales colli Intertransversales lumborum d xxvi CONTENTS. CHAP. V. • • 9.40 Muscles of the extremities . • • **" Muscles of the superior extremity • ■ io- Muscles of the shoulder . • • l°' Posterior scapular region . • .to. Supra-spinatus . • • • l ' Infra-spinatus . • • . ,441 Teres minor . _ 040 Teres maior . " Anterior scapular region . • • **° Subsapularis • • .to. External scapular region . . • ~+* Deltoides ...•»*• Muscles of the arm . "4b Anterior brachial region . • .to. Coraco-brachialis . . • .to. Biceps flexor cubiti . . • 247 Brachialis internus .... 248 Triceps extensor cubiti . . . ib. Muscles of the fore-arm . . . 250 Anterior region of the fore-arm . . ib. Pronator teres ib. Flexor carpi radialis . . . 251 Pa'lmaris longus ib. Flexor carpi ulnaris . . . 252 Flexor digitorum sublimis vel perforatus . 253 Anterior deep region of the fore-arm . . 255 Flexor digitorum profundus vel perforans . ib. Flexor longus pollicis manus . . . 256 Pronator quadratus . . . 257 Posterior superficial region of the fore-arm . 258 Extensor digitorum communis . . ib. Extensor proprius minimi digiti . . 259 Extensor carpi ulnaris . . . ib. Anconeus .... 260 Posterior deep region of the fore-arm . . 261 Extensor ossis metacarpi pollicis . . ib. CONTENTS. xxvii Extensor primi internodii pollicis manus . 262 Extensor secundi internodii pollicis manus . ib. Indicator ..... 263 Muscles of the hand . . . 264 External palmar region . . ib. Adductor brevis pollicis manus . . ib. Opponens pollicis . . . . ib. Flexor brevis pollicis manus . . . 265 Adductor pollicis manus . . . 266 Internal palmar region . . . ib. Palmaris brevis . . . . ib. Abductor minimi digiti . . . 267 Flexor proprius minimi digiti . . ib. Adductor ossis metacarpi minimi digiti . . 268 Middle palmar region . . . ■ ib. Lumbricales . . . . ib. Interossei .... 269 1. Abductor indicis . . . ib. 2. Adductor indicis . . . 270 3. Abductor digiti medii . . . ib. 4. Adductor digiti medii . . . 271 5. Abductor digiti annularis . . . ib. 6. Adductor digiti annularis . . . ib. 7. Abductor minimi digiti . . . 272 The enveloping aponeurosis of the upper extremity ib. CHAP. VI. Muscles of the inferior extremity . . 274 Region of the hip . . . ib. Muscles of the haunch and thigh . . ib. Gluteus maximus . . . ib. Gluteus medius .... 276 Gluteus minimus .... 277 Pelvi-trochanteric region . . . -279 Pyriformis . . . ib. Obturator internus .... 280 Obturator externus . . . 281 XXV111 CONTENTS. Gemellus superior . Gemellus inferior Quadratus femoris . Anterior femoral region Sartorius . Rectus femoris Triceps extensor cruris; internus, cruraeus Internal femoral region Pectineus Gracilis . Adductors of the thigh Adductor longus Adductor brevis Adductor magnus Posterior femoral region Biceps femoris Semitendinosus Semimembranosus Tensor vaginae femoris Aponeurosis of the thigh Muscles of the leg . Anterior region of the leg Tibialis anticus Peroneus tertius Extensor longus digitorum pedis Extensor proprius pollicis pedis Peroneal region Peroneus longus Peroneus brevis Posterior region of the leg Gastrocnemius externus et internus Soleus Plantaris Popliteus Flexor longus digitorum pedis Flexor longus pollicis pedis Tibialis posticus vastus externus, vastus 282 ib. 283 284 ib. 285 286 28S ib. 289 ib. ib. 290 291 293 ib. 294 295 ib. 296 298 ib. ib. 299 300 301 303 ib. 304 305 ib. 307 308 ib. 310 311 312 CONTENTS. Muscles of the foot Dorsal region Extensor brevis digitorum pedis Interossei externi . Plantar region Flexor brevis digitorum pedis Abductor pollicis pedis Abductor minimi digiti pedis Flexor digitorum accessorius Lumbricales pedis . Flexor brevis pollicis pedis Adductor pollicis pedis Flexor brevis minimi digiti pedis Transversus pedis . Interossei interni Aponeurosis of the leg Annular ligament of the instep Observations on the muscles . Bursas mucosas, or mucous bags Vascular system ART. V. CHAP. I. Organs of circulation The heart and its envelopes The pericardium The blood The heart The right side of the heart The right auricle The right ventricle Commencement of the pulmonary artery XXX CONTENTS. The left side of the heart The left auricle The left ventricle Organization of the heart The vessels of the heart General observations on the heart Table of the arteries Of the arteries in general Structure of the arteries The aorta The arteries which the aorta gives off at its origin The right coronary artery The left coronary artery The arteries of the arch of the aorta Arteria innominata . Primitive carotid arteries External carotid artery Anterior branches of the external carotid artery Superior thyroid artery External maxillary artery Branches of the external maxillary artery The lingual artery . Posterior branches of the external carotid artery Occipital artery The posterior auricular artery Internal branch of the external carotid, or inferior pharyngeal artery Branches which terminate the external carotid ar tery Temporal artery Internal maxillary artery Branches of the internal maxillary artery behind the neck of the condyle of the jaw Middle meningeal artery Inferior dental, or maxillary artery Branches of the internal maxillary between the pterygoid muscles Posterior deep temporal branch CONTENTS. xxxi Masseteric artery .... ib. Pterygoid arteries . ib. Branches of the internal maxillary artery in the zygomatic fossa ib. Buccal artery .... 366 Anterior deep temporal artery ib. Alveolar artery .... 367 Infra-orbitar artery .... ib. Branches of the internal maxillary artery in the spheno-maxillary fossa ib. Vidian or pterygoid artery ib. Superior pharyngeal artery ib. Superior palatine artery ib. Spheno-palatine artery 368 Internal carotid artery ib. Ophthalmic artery .... 369 The lachrymal artery ib. The central artery of the retina ib. Arteries sent off by the ophthalmic above the optic nerve 370 The supra-orbitar artery ib. The posterior ciliary arteries . ib. The long ciliary arteries ib. The superior and inferior muscular arteries 371 Arteries sent off by the ophthalmic in its course along the inside of the optic nerve ib. The posterior and anterior ethmoidal arteries ib. The superior and inferior palpebral arteries ib. Branches which terminate the ophthalmic artery . ib. The nasal artery .... ib. The frontal artery .... 372 The communicating artery of Willis ib. The artery of the choroid plexus ib. The anterior cerebral artery . ib. Middle cerebral artery ib. Subclavian artery .... 373 Branches of the subclavian artery 374 Vertebral artery .... ib. xxxii CONTENTS. Basilar artery Inferior thyroid artery Inferior branches of the subclavian artery Internal mammary artery Superior intercostal artery External branches of the subclavian artery Transverse cervical or posterior scapular artery Superior scapular artery Posterior or deep cervical artery Axillary artery Branches of the axillary artery Acromial artery Superior thoracic artery Long thoracic or external mammary artery Inferior scapular Posterior and anterior circumflex arteries Brachial artery Superior muscular branch, or deep humeral The inferior muscular artery . The ramus anastomoticus magnus The external branches of the brachial artery Branches by which the radial artery terminates The radial artery The ulnar artery Arteries furnished by the thoracic aorta . Bronchial arteries . ^Esophageal arteries Posterior mediastinal arteries Inferior intercostal arteries Arteries furnished by the abdominal aorta The right inferior diaphragmatic artery . The left inferior diaphragmatic artery Cosliac artery Coronary artery of the stomach Hepatic artery . Splenic artery Superior mesenteric artery CONTENTS. xxxiii Branches which are furnished on the left side of the superior mesenteric artery 397 The inferior mesenteric artery 399 Arteries which are furnished laterally by the abdo minal aorta . 400 Surrenal arteries ib. Renal or emulgent arteries 401 Spermatic arteries . 402 Lumbar arteries ib. The arteries which terminate the aorta below 403 Middle sacral artery ib. Primitive iliacs ib. Internal illiac or hypogastric artery 404 Branches of the internal iliac artery ib. The ilio-lumbar artery ib. The lateral sacral artery ib Gluteal or posterior iliac artery 405 Umbilical artery 406 Vesical arteries ib. Obturator artery .... ib. Middle haemorrhoidal artery . 407 Uterine artery .... ib. Vaginal artery .... ib. Ischiatic artery .... ib. Internal pudic artery ib. Branches of the internal pudic artery 408 External iliac artery 409 The epigastric artery ib. Circumflex iliac artery ib. Femoral artery .... 410 Internal branches of the femoral artery . 411 External pudic artery ib. External branches of the femoral artery . 412 Superficial muscular artery ib. Anterior branches of the femoral artery . ib. Abdominal subcutaneous or external epigastric ar- tery .... ib. e XXX1V CONTENTS. Posterior branches of the femoral artery Arteria profunda femoris, or deep muscular Branches of the profunda femoris Popliteal artery Branches of the popliteal artery Anterior tibial artery Branches of the anterior tibial artery Dorsal artery of the foot Peroneal artery Posterior tibial artery Branches of the posterior tibial GENERAL OBSERVATIONS. GENERAL OBSERVATIONS. The science of anatomy investigates whatever enters into the composition of animated beings; and the dissec- tion of their dead bodies is the chief means of prosecuting the study. The anatomist isolates portions, to display them more distinctly; he injects vessels, to exhibit their course; macerates some parts, to unravel their intimate conformation; dries other parts, to preserve them for future reference; and uses various other processes to facilitate his inquiries into the intricate and complicated machinery of the animal frame. Anatomy, therefore, may be said to be the science of animal organization ; and it requires such an examination of the instruments of life, as shall disclose their number, size, situation, form, colour, connection, texture, and functions. This science comprehends the structure of organized beings in general; but it is the anatomy of man only which forms the subject of the present Introduction. The anatomy of the human body explains its structure under two different conditions : the first is a healthy state of the organs, termed special anatomy; the second is a diseased state producing alterations of structure, termed XXXVlii GENERAL OBSERVATIONS. morbid or pathological anatomy. I confine myself to a description of the structures and organs of the adult in the former of these conditions. The human body is composed of solids and fluids, united in different proportions. The solids give the form and consistence to the different parts of our bodies, and they consist of bones, ligaments, muscles, tendons, vessels, nerves, etc. The fluids form the greatest part of the body, and are the blood, chyle, and all the secreted liquids, as urine, sweat, saliva, tears, bile, &c. These are all con- tained either in vessels, cells, or reservoirs. When the fluids of the animal frame are separated from the solids, their weight is in the proportion of eight to ten. This has been ascertained by an examination of human bodies found buried in the dry sands of Arabia, with their fluids evapo- rated and their solids remaining perfect; and the fact is confirmed by experiments on inferior animals. The anatomy of the solids has been divided into vari- ous branches, expressive of the parts referred to; as, Osteology . Syndesmology Myology Splanchnology Adenology . Angiology . A description of the bones. --------------the ligaments. -------------- the muscles. -------------- the viscera. -------------- the glands. -------------- the structure and distri- bution of the vessels. Neurology . . .--------------the nerves. Dermology . . . -------------- the skin. The description and composition of the animal fluids come under the head of Physiology particularly. The solid parts of the body are named organs, or the instruments by which the functions are exercised. GENERAL OBSERVATIONS. XXxix These solid parts of our fabric, when minutely examined, are found to consist ultimately of layers of minute fibres, or filaments, varied in appearance and texture, according to the use and offices of the part which they compose. As the different organs which constitute the body are of a more simple or complex structure, they are made up of one or more tissues or textures, which are the original materials, performing the same function, in whatever part of the body they exist. Most of the organs of the body are composed of a variety of these elementary textures, which are spread out in the form of membranes, collected into cords, or hollowed out into canals ; and by their di- versity of combination, figure, and colour, they produce all the modifications of structure and functions which dif- ferent organs possess. Bichat, an eminent French anatomist, pointed out the simple analysis or division of the body into its elementary parts; and the knowledge of these has been of the utmost importance in the investigation and treatment of diseases, as well as of the greatest convenience in anatomical ar- rangement. The systems of texture may be placed in the following order: 1st, the bony system ; 2nd, the cartilaginous ; 3rd, the fibrous; 4th, the muscular; 5th, the vascular; 6th, the nervous; 7th, the mucous ; 8th, the serous; 9th, the glandular; 10th, the adipose; 11th, the cellular; 12th, the dermoid. These are further subdivided : as the bony system, into the bony and medullary; the cartilaginous, including the fibro-cartilaginous; the vascular is divided into the arterial, xl GENERAL OBSERVATIONS. the venous, and the lymphatic, etc. But in this place I wish to take a more general view of animal structures, and these twelve divisions will comprehend the whole. The elementary tissues are variously combined and pro- portioned ; the cellular, vascular, and nervous tissues, give origin to a variety of compound solids, and these solids are furnished with the properties suited to the place they occupy and the offices they discharge. It is difficult to ascertain the chemical ingredients which enter into the composition of the body; but, according to our present knowledge of animal chemistry, the inorganic elements consist of carbon, azote, oxygen, hydrogen, phos- phorus, sulphur, iron, calcium, sodium, potassium, etc. These different chemical elements again form organic elements: as gelatin, or what is called animal jelly ; fibrin, or a whitish elastic filamentous substance; albumen, a vivid transparent fluid like the white of an egg, coagulating by alcohol and heat; mucous, a viscid transparent fluid, incapable of coagulation ; fat, or animal oil, a well-known substance, insoluble in water, and readily melting by the action of heat. More particular notice, however, of the formation and chemical composition of individual structure will subsequently occurc. c For the several other chemical products, I refer the reader to Berzelius on Animal Chemistry. ANATOMY OF THE HUMAN BODY. CHAP. 1. OF THE BONES IN GENERAL, OR OSSEOUS SYSTEM. The bones are the hardest parts of animal bodies: they are a firm and common basis, on which the moving powers are fixed; they constitute a framework for protecting the vital organs, as the heart and lungs, or form complete cases where the more delicate parts of our organization, as the brain and spinal marrow, are securely lodged. They also constitute a series of levers, by means of which, through the agency of the muscles, locomotion and the various and numerous offices of life are performed. A complete assemblage of conjoined bones form the skeleton: if it is united by its natural ligaments, it is de- nominated a natural skeleton; if by wires, it is called, though incorrectly, an artificial skeleton, signifying, how- ever, that it is artificially articulated, which indeed is the most useful mode of connecting bones ; for, by this means, the joints can be moved and examined at pleasure ; on the contrary, bones united by their ligaments have the joints rigid and concealed. The appearance of the skeleton is different in different subjects, according to the period of life and sex: the pre- vol. i. 2 2 OSSEOUS SYSTEM. sent object is to describe its formation and particular orga- nization in the adult, either male or female. The forms of the bones are sufficiently obvious in many parts of the body so as to give the points to the outline ; determining the size, proportion, and motions of its several members. The bones afford attachments to the moving powers, i.e. the muscles to their tendons, and also to the ligaments. OSSIFICATION. The bones experience many changes before they arrive to the term of their perfection, which is not until about the twentieth year. In the first periods, their consistence does not exceed that of the other parts. In four weeks they harden and appear cartilaginous, their form is perfect, and they are covered by their peculiar membrane, the periosteum. To- wards the eighth week their vessels commence to carry red blood, instead of the colourless fluid which before cir- culated in them. It is at this period that the true ossifi- cation begins, departing from certain centres which are called the points of ossification, and these vary according to the forms of the bones. In the flat bones, the ossific matter is deposited in a radiated manner; in the long bones, in parallel lines. The larger bones are the first formed, with the excep- tion of the minutest in the body, viz. those of the ear. In these ossification is the soonest completed; and they ex- ceed all the others in density, and in the proportion of the hard matter of bones which they contain. The use for which a bone is destined, appears to have some influence on the degree of rapidity with which it is formed and developed. The jaw bones are thus early matured, as they are so soon in life required for use. On OSSEOUS SYSTEM. 3 the other hand the sternum and coccyx are tardily per- fected, because it is necessary that the cavities which they help to inclose should be kept somewhat in a cartilaginous state until a later period. • Most of the bones are formed of several pieces, as may be more particularly observed in the long ones, which have their extremitiesa separated from their body by a thin par- tition of cartilage, and it is some time before the whole is united. In the skull, some of the bones, in the first rudiments of ossification, display a radiated calcareous phosphate, di- verging from the centre to the circumference. Unossified substance at first occupies the interstices left between them, but subsequently additional bony fibres proceed until the cranium is perfect. When ossification is completed, the bones still continue to undergo different changes. The general growth in sta- ture is completed with the the process of ossification; but increase of bulk is still for a long time advancing to middle age, when the bone is stronger and less vascular; and the different elevations of the surface become more prominent and marked, particularly in individuals accustomed to strong exercise. Finally, as we advance in years, vitality progressively decreases ; and in extreme old age the earthy substance predominates, and the bones become extremely fragile. eminences and depressions of bones. A variety of eminences and depressions characterise a number of the bones. The eminences are all those pro- jections, prolongations, or productions, observable on their surfaces ; and different names have been assigned to these, derived from their figure, situation, and use. Termed epiphyses or apophyses. 4 OSSEOUS SYSTEM. These eminences are termed heads, when they are con- vex, roundish, and smooth on their surface. Necks, when smallest at the middle, and gradually increase toward the extremity. Condyles, when the head is rather long and unequally rounded. Tubercles or tuberosities, when un« even, rough, and irregular. Spines or spinous processes, when sharp or pointed. Long elevations with sharp edges are called crista. Such processes as terminate in a sharp point or rather edge, receive the general name of coronoid, though most of them receive particular names from their resemblance to other things, as mastoid, styloid, coracoid. Processes are also named from their situation, as oblique, transverse, he. Some from their uses. Thus two tubercles on the os femoris are designated as trochanters, because they serve to turn that bone. The depressions are either deep or superficial. Of the deep depressions or cavities, some are termed cotylce, or cotyloid, from their being like a cup, such as the greater cavity which receives the head of the former. Others are named alveoli or sockets, as those in which the teeth are lodged. The more shallow or superficial cavities are called glence or glenoid, as that part of the scapula which receives the head of the humerus. The cavities of the interior of bones will be described when considering their structure. These eminences and depressions are most strongly marked in those persons who take very robust exercise, and in the male more than the female, in the adult more than the infant. The eminences of articulation are generally the expan- ded extremities of bones, forming surfaces of union with other bones, in which there are corresponding depressions. The mode of union varies with the form and use of the bones thus united ; some being immoveably united, others having a limited or a free motion. OSSEOUS SYSTEM. 5 Muscular depressions are in proportion to the strength or action of the muscles to which they give origin; and the degree of projection of the eminences for insertion are always a sure sign of the strength of the muscles attached ♦> them, and the energy of their motion. Asperities on the surface of bones in general show where tendons or muscles are implanted. An extended line usually indi- cates the attachment of a broad tendon ; projecting points have tendons or ligaments corresponding. It may be easily conceived that the moving powers must act with greater advantage by being removed farther from the centre of the bone, by means of such projecting points. The eminences for the insertion of ligaments also afford a similar advantage, by removing, in some degree, ijie ligament from the articulation, thus facilitating the motion of the latter, as we may observe in the elbow and the knee. Eminences and depressions from apparent impression, are such as the irregularities of the inner surface of the skull, or such as muscular impressions on other bones pre- sent. They are supposed to be occasioned by the pres- sure of different organs on the surface in their growth or actions. If these impressions are not actually the result of the compression of he organs on the bone, they show that the bones are provided with forms admirably accom- modated to the adjacent parts. FORMS OF BONES. Viewed in respect to form, bones have been arranged under four classes—the long, the broad, the short, and the mixed bones. The first in general belong to the parts of locomotion, where they become levers moved in various directions "by the muscles. These have all a medullary canal, and their 6 OSSEOUS SYSTEM. extremities are considerably larger than their bodies, and are porous and reticulated, which gives them a greater de- gree of lightness, increases the articulating surfaces, and consequently diminishes their liability to luxation. The body of these bones is usually round. The greater di# tance these are from the trunk of the body, the less is their volume, but the greater their number. The second, or broad bones, are little connected with locomotion, serving chiefly for the insertion of muscles which proceed to the long bones, and form ordinarily by their union the walls or parietes of certain cavities, as the cranium and .pelvis. They are nearly equal in length and breadth, but vary in thickness. They have two lamina; and in the cranium the internal is thinner and harder, and has therefore the name of tabula vitrca. The third, the short bones, are situated in those parts in which solidity and- motion must be united, as in the spine, the wrist, and the instep, where their number insures these two properties, namely: solidity, because the force of external mechanical shocks is expended on the wide surface by which they are connected ; and mobility, be- cause from their individual partial motions, there results collectively a very extensive general one. Besides these three classes of bones, there is a fourth, termed by Meckel mixed bones, for they seem to be form- ed by the union of the bones of the other classes, chiefly of the second and third, being composed of flat and short portions, viz. the sphenoid, temporal, and ethmoid bones. COLOUR OF BONES. The colour of the bones depends upon the age, or the manner in which they have been prepared. In the adult the colour is of an opaque white, when fresh, more or less tinged with red; in younger subjects, however, the bones OSSEOUS SYSTEM. / are more vascular and coloured than in those of more advanced years. •;u TEXTURE OF BONES. * The texture of the bones, like every other animal struc- ture, has a fibrous appearance. The nature of bony fibre ] is everywhere the same, but being differ- ently arranged admits of two essential mo- difications : in one bone, or in part of the bone, the fibres, more or less distant from each other, display a profusion of cells ; in other parts, closely compressed toge- ther, they form a kind of compact sub- stance, in which they cannot easily be discerned. By sawing a cylindrical bone in the longitudinal direction, the arrange- ment of the fibres is evident. Fig. 1 is a section of the thigh bone ; a, a, the extre- mities, having to some extent a shell of compact texture, crowded with small cells, diminishing in size but increasing in num- ber as they approach the articulation. They are named cancelli, or spongy struc- ture, c, the cavity for containing the marrow. The hollowness increases the diameter, consequently the comparative !±B^^^!Mj$ strength of the cylinder, b, b, the walls or sides of the shaft, very solid. Observe, the compact texture is thicker near the middle of the bone, where the greatest forces are most frequently applied. The short bones are almost entirely of a cellular struc- ture, covered only by a thin layer of compact texture ; in this respect their organization is similar to the heads of long bones. 8 OSSEOUS SYSTEM. The broad bones are usually composed of two compact plates of a moderate thickness, having a cellular structure interposed; but in general wherever broad bones are thin, and there is a deficiency of cancelli, very powerful mus- cles meet, and by their thick layers compensate for the want of solidity in the bone, as in the occiput, ilium, sca- pula, etc. periosteum.b This is a fibrous membrane, so called from its surround- ing all the bones, and providing them with a covering everywhere extended over them, except in such parts as are tipped with cartilage, and the teeth which are protected by enamel. The ancients had figured to themselves the periosteum as extending from one bone to another over the articula- tion, and thus forming a continued bag for the whole ske- leton. This idea is nearly correct; for although the perios- teum ceases at the joint, it is interwoven with the ligaments that surround the joints : in this manner continuity may be conceived. The periosteum in infancy is slightly united to the bone, and is removed from it with the utmost facility. In the adult the adhesion is more firm : it is excessively so in an aged person. The inner surface of this membrane is firmly fixed to the bone by numerous vessels and fibrous threads, particularly in the extremities of the long bones and on the short bones, which we can easily conceive by the great number of apertures we see in them. The connexion between the periosteum and the adjacent organs is much b In the English edition the description of the Periosteum is deferred until the author is on the subject of Fibrous Membranes; but as so immediately connected with the Osseous System, it was considered proper to place it where it now is. OSSEOUS SYSTEM. 9 varied; for the most part the muscles are attached to, or glide upon it, and it is more or less united to them and to the integuments by cellular membrane. The periosteum borrows its vessels from those adjacent. Their innumerable branches form an intricate net-work, which is rendered very striking by injections, especially in infants; they are then lost in the compact texture of the bone, or are returned to the surrounding parts. This membrane is no doubt supplied with nerves, though so minute as not to be easily demonstrated. Like bone in its healthy and natural state, it possesses little or no sensi- bility ; yet when inflamed its feeling is exceedingly pain- ful, so that we cannot but allow it to be endued with nerves. That absorbent vessels also penetrate the periosteum, is argued from its restoration from diseases. In some cases it attains an unnatural thickness, and in process of time regains its natural tenuity, which can be the result only of the action of the absorbents. The periosteum is subservient to several uses. 1st. It is the nutritious membrane of the bone; it endows its exterior with vitality; and if it is separated from it, the surface of the bone perishes. 2d. It gives convenient in- sertion to nearly the whole of the fibrous system; viz. the tendons, ligaments, aponeuroses, and also muscles, are at- tached to this organ. 3d. By means of the smooth sur- face of the periosteum, the action of the muscular fibres and the tendons is easy, and the effects of friction are averted. COMPOSITION OF BONKS. The composition of bones, whatever may be their forms, is of the same nature: they consist of a mixture of earthy and animal matter. vol. i. 3 10 OSSEOUS SYSTEM. The existence of the first is proved by burning bones in fire: combustion destroying the animal matter, leaves a brittle substance, which is the earthy part, of the same form with that of the bone. The animal part of bone is not less evident, for by im- mersion in a weak acid the earthy matter is dissolved, and there remains a cartilaginous body, flexible and elastic, bearing the same form as the bone. These two substances are the essential component parts of bones. The earthy is intended to provide them with the degree of strength and solidity that characterise them; the animal parts endow the bone with the principles of vitality, growth, and nutrition. The skeleton consists of about two hundred and fifty- two0 bones, which are divided into those of the head, the trunk, and extremities; some of them are single, and others are in pairs. There are Frontal . . Parietals . . Osfrontis . . Ossa parietalia 1 2 T3 O Occipital . . Temporal . . Sphenoidal . . Ethmoid . . Os occipitis . . Ossa temporum Os sphenoides Os ethmoides . . 1 2 ] 1 t*-l Nasal . . Ossa nasi . . 2 o t/} « Malar . . Ossa malarum 2 CD a o CO > Lachrymal . . Upper jaw bones Palate bones . . Inferior turbinated bones Ossa lachrymalia Ossa maxillaria superiorc Ossa palatina Ossa turbinata 2 2 2 2 i Vomer . . 1 «3 Lower jaw . . Os maxillare inferius . 1 Teeth Denies . . 32 - Tongue bone . . Os hyoides . . 1 c The exact number of bones in the human frame is variable: the sesamoid bones and ossa wormiana are not constant; and in reckoning the bones of the skeleton, the small bones of the ear are usually omitted. OF THE HEAD. 15 CHAP. II. BONES OF THE HEAD. These comprehend the bones of the cranium and face, consisting of twenty-two in number. Some of them are in pairs, but others are only single bones. In the cranium or skull there are two pairs and four single bones, viz. 2 Parietals. 2 Temporal. 1 Frontal. 1 Occipital. 1 Ethmoid. 1 Sphenoid. To the face there are six pairs and two single bones, viz. 2 Nasal. 2 Lachrymal. 2 Malar. 2 Superior maxillary. 2 Palatine. 2 Turbinated. 1 Vomer. 1 Inferior maxillary. The cranium is the vaulted cavity for lodging the brain, its membranes and vessels. The inner and outer surfaces of the bones are composed 2 of compact layers, Fig. 2, a called the ex- ternal and b the internal tables of the skull. They are not parallel to each other, but in some places very compressed. There is an intermediate cellular texture, c, between them, term- ed diploe, which is similar to the cancelli of other bones, 16 OSSEOUS SYSTEM and it serves a like purpose, viz. to convey vessels and nerves from one region to another. The character of the two tables differ; the external is fibrous, the inner ex- ceedingly compact and brittle, so as to obtain the name of vitreous. THE SUTURES. Upon the surface of the skull we observe various lines, dividing it into different portions, as in Fig. 3, the upper part of the skull. These lines are the joining of the several bones to each other, and form a resemblance, on a su- perficial view, to the stitches of a seam; they are denominated su- tures. Their origin is this: the radiated fibres of the bones in their growth approach each other, the fibres of one bone entering the inter- val of the fibres of ano- ther bone, forming the serrated line of union called suture. a, a, The coronal suture, has its name from being situ- ated at that part of the head upon which the ancients were used to place the laurel or olive crown, given to the vic- tors in their games. It passes transversely over the skull, and joins the frontal with the parietal bonas. b, The sagittal suture, named from its straight course. It extends from the middle of the superior margin of the frontal, to the angle of the occipital bone. It is the union OF THE HEAD. 17 of the two parietal bones. This suture is occasionally continued down the frontal bone to the nose: this part of it is then named the frontal suture. c, The lambdoidal suture, receiving this name from its resemblance to the Greek A. It commences at the ter- mination of the sagittal suture, and extends on each side to the base of the cranium. It joins the occipital to the parietals above, and to the temporal bones below. There is great irregularity in this suture: it is frequently diverted from its regular course by the interposition of little bones (separate ossifications), d, d, which, from being of a tri- angular shape, have been called ossa triquetra, or ossa wormiana, in compliment to Olaus Wormius, an anatomist, who first particularly described them. The superior portions of the temporal bones are joined to the parietals by a thin, indented, yet scaly overlapping of the former, e, e, hence named the squamous suture. Near the occipital angle it loses its squamous character, and is simply united by a serrated line, under the name of additamentum sutures, squamosa. Two other sutures are sometimes reckoned, viz. the ethmoidal and the sphenoidal; but they are a union of the ethmoid and sphenoid bones to those adjacent, by irregular lines, by no means having the character of a suture. vol. t. 4 18 OSSEOUS SYSTEM FRONTAL, BONE. Os frontis. This bone forms the forehead, part of the temples, and the roof of the orbits ; its shape has been compared to a clam shell. Fig. 4 is a front, Fig. 5 a back view. Two eminences, a, a, mark the 4 situation of the frontal sinu- ses. These are formed by an apparent separation of the two tables of the skull, leav- ing very considerable cavi- ties, which communicate with the nose.d On each side of the forehead we observe b, Fig. 4, the temporal arch, at first strongly marked, but less so as it passes upwards. The hollow forms part of the temporal fossa. and at the lower edge of this bone is c, the nasal process, and ethmoidal notch. On the ridge over which the eye- brow is placed we observe d, a hole; sometimes it is only a notch in the bone, as on the other side of this specimen, though it is there completed by a ligament, so as to form a hole called the upper orbitary holee. The ridges just mentioned terminate at e, e, the external angular pro- cesses. The angles opposite are the internal angular pro- cesses. Between these are f f the orbitar plates, slightly concave, and have near the outer angle a depression* for the reception of the lachrymal gland. In the middle d These cavities increase the intensity of the sound of the voice, and render it more melodious. c Foramen supra-crbitarium. For the passage of first branch of fifth pair of nerves. f Fossa lachrymalis. OF THE HEAD. 19 On the internal surface, Fig. 5, are slight depressions, answering to the convolutions of the brain, h, the frontal spine, is a sharp ridge com- mencing at the ethmoidal notch, and extending up* wards about an inch, where it divides into two ridges with a shallow groove be- tween them,called the fron- tal furrow. At the root of the spine at A, is a small hole, which not perforating the bone or leading to any cavity, is called the blind hole%. i, i, the opening of the frontal sinuses. The os frontis is joined above and behind with the ossa parietalia, which junction terminates at a line running horizontally backwards from the point of the angular process ; between those two points and behind as far as the ethmoidal notch, it joins with the sphenoid bone on each side; within the ethmoidal notch it receives the ethmoid bone, which joins to the orbitar plates, at the anterior part of which it unites with the os lachrymale; in front it joins its nasal process and spine with the ossa nasi and ethmoid bone, and by its outer angular processes with the malar bones. The muscles attached to the os frontis are three pairs, viz. the temporal muscle, the corugator supercilii, and orbicularis palpebrarum. It is also covered by the occi pito-frontalis. g Foramen c«cum. 20 OSSEOUS SYSTEM the parietal bones, ossa parietalia, Are a pair, forming the sides and vertex, or top of the head. Externally, Fig. 6, each bone is convex ; and as it has four angles, they are denominated according to their relative situation in the skull, the frontal and temporal angles, and the superior or inferior occi- pital angles. The mar- ginal edges also are named from their connexions, as a in this and the subse- quent figure ; the anterior edge is called the frontal margin; b, the parietal margin; c, the occipital margin; d, the temporal margin. On the convex surface is a trans- verse arched impression, e, which marks the attachment of the temporal muscle. On the internal and concave surface, Fig. 7, f,f, are im- pressions or furrows,which are for the ramifications of the artery of the dura ma- ter, or outer membrane of the brain. Sometimes part of the artery runs in a ca- nal in the bone, as in this specimen at the temporal angle. Near the superior margin there is commonly a small hole,through which a vein passes from the in- teguments of the head to the longitudinal sinus. OF THE HEAD. 21 The parietal bone is joined by its frontal edge to the os frontis; by the parietal edge to its fellow; by its occipital edge to the os occipitis: and by its temporo-sphenoidal edge to the temporal and sphenoid bones. The only muscle attached to the parietal bone is the temporal. THE OCCIPITAL BONE, OS OCCipitis, Is situated at the back part of the head, and forms part of the base of the skull It is convex externally, Fig. 8; concave internally, Fig. 9. The most remarkable parts to be noticed on the exte- rior, Fig. 8, are a, the oc- cipital angle ; b, a promi- nence called the tubercle, from each side of which there is a transverse arch- ed ridgeh, and below is another ridge, following nearly the same direction. These are to be borne in mind as indicating the at- tachment of some of the muscles of the head. There are also several depres- sions, shewing the insertion of muscles. At the under and fore part of the bone is c, the great opening*, through which passes the medulla oblongata, or upper part of the spinal marrow, its membranes, the vertebral arteries, and the spinal accessory nerves; d, the anterior condyloid b Linea semicircularis, or arcus traversus. i Foramen magnum occipitis. 22 - OSSEOUS SYSTEM holes, through which the lingual nerves pass; e, e, the pos- terior condyloid holes, for the passage of the veins of the neck: frequently one or both of the latter holes are want- ing, in which case the veins proceed through the foramen magnum; f f the condyles or smooth eminences for arti- culating with the first bone of the neck; g, the basilary or cuneiform process. The inner surface, Fig. 9, is concave, and divided by a crucial ridge, b. To the crucial ridge are attached processes of the dura ma- ter, viz. from a to b, a por- tion separating the poste- rior lobes of the cerebrum; from b to c, a portion di- viding the cerebellum; and from b to g each side, ano- ther, which separates the cerebrum from the cere- bellum. In this curved ridge from b to g, are seen transverse grooves, shewing the situation of the lateral sinuses; c, the great foramen; e, e, the condyles; f the basilary process. The occipital bone is united by its pari- etal margin to the parietal bones; by its temporal to the margin of the mastoid portion of the temporal bones; by its basilary margin to the petrous portion of the same bone ; and by its basilary process to the sphenoid bone. The muscles attached to the os occipitis are ten pairs, viz. the trapezii, complexi, splenii, recti postici majores, et minores capitis, obliqui superiores capitis, recti late- rales, recti interni majores, et minores capitis, and the occipito-frontales. OF THE HEAD. 23 the temporal bones, ossa temporum, Are a pair. They are so named because they occupy the region of the head where the hair usually commences to whiten, thus indicating the period of life. They are ir- regular in their form, and unequal in their thickness. Fig. 10 is an outer view. Each bone is distinguished by two distinct portions : the upper part is thin and of a scaly character, hence named the squamous portion; the other half of the bone is of a tri- angular form, passing inwards and downwards, and being of a close texture and rocky hardness, is called the petrous portion. If a horizontal line was drawn from b, the squa- mous portion would be all that part above the line. It forms the chief part of the temple. The squamous por- tion is bounded at its base by b, the zygomatic process, which is a thin and narrow projection of bone; at its root it has c, a tubercle or eminence, and terminates in b, an indented process, which, from its union with the malar or cheek bone, is called the malar process. Immediately behind the eminence c, is a cavity for the articulation of the lower jaw. At the back part of this cavity is an appa- rent division in the bone, the glenoid fissure, through which passes a nerve called the corda tympani. On the lower surface of the eminence just mentioned, the jaw moves when brought forwards, d is a deep hole, the ex- ternal auditory passage*. From the lower part of the bone ' ) Meatus auditorius externus. 24 OSSEOUS SYSTEM is a remarkably long and pointed process, e, which, from having some resemblance to an ancient style, or iron wri- ting pen, is named styloid process. Several muscles are attached to this slender portion of bone, and derive their names from it. At the root of the process, /, is a ridge of bone termed the vaginal process, imagination having formed it into the likeness of a sheath to the styloid process. Further behind is g, the mastoid process; it is a very con- siderable prominence, the texture of which is cellular, but the cells are seen only in a section of the part. There is one or more holes at the back part of this process, seen at c, Fig. 11, called the mastoid foramen, or foramina. Be- tween the root of the styloid and mastoid processes, is the stylo-mastoid foramen: it is the passage of the portio dura of the seventh pair of nerves. Fig. 11 is the inside view. On the squamous portion we observe marks of the convolutions of the brain, and a, the edge bevelled off where it overlaps in joining to the parietal bone. On the pe- trous portion is b, the inter- nal auditory passage^, by which the nerves of hearing have access from the brain to the ear. Posterior to this is a foramen, called the aqueduct of the cochlea: it serves for the entrance and exit of the blood-vessels of the ear. On the opposite side, in the anterior part of the petrous portion, is a small hole called the vidian foramen. k Meatus auditorius internus. It should be observed, that this opening soon divides into two: the first, called the aqueduct of Fallopius, for that division of the seventh pair of nerves, the portio dura, which is distributed to the face ; the second foramen admits the other division of this nerve, the portio mollis, by several small apertures, into the intricate passages of the ear, to become the proper organ of hearing. OF THE HEAD. 25 Near the point called the inferior angle is /, the entrance of the carotid canal, for the passage of the chief artery of the brain; g, the bony part of the eustachian tube1. At the base of the bone is the jugular fossa, or thimble-like depression, made by the first turn or commencement of the jugular vein. The temporal bone is united by its malar process to the zygomatic process of the os malse; by the inferior edge of the squamous portion to the spinous process of the os sphenoides; by the superior edge of the same part to the temporo-sphenoidal edge of the os pari- etale ; by the superior edge of the mastoid portion to the temporal angle of that bone; by the inferior part of the mastoid portion, and the petrous portion, to the temporal and basilar edges of the os occipitis, and the posterior cli- noid process of the os sphenoides. There are sixteen muscles attached to the temporal bone, viz. the temporalis, masseter, retrahens auris, occi- pito-frontalis, sterno-cleido mastoideus, complexus minor, splenius, digastricus, stylo-hyoideus, stylo-glossus, stylo- pharyngeus, and the constrictor pharyngeus superior; and the muscles moving the small bones of the ear, the tensor tympani, laxator tympani, externus mallei, and stapedius. Besides the parts which have been described, the tem- poral bone contains the organ of hearing, which includes the ossicula auditus, etc. As, however, these parts can- not be understood till several sections of the temporal bone have been made, I shall refer the reader for a .further de- scription to the article on the senses. 1 Iter a palato ad aurem. It is named the eustachian tube from Eustachius, an eminent anatomist, who discovered it. VOL. I. 5 26 OSSEOUS SYSTEM THE SPHENOID BONE, Fig. 12 and 13, So called from its situation in the base of the skull, where it wedges in and locks together most of the other bones, for it is united to fourteen distinct bones. Its general re- semblance to a bat with extended wings, has given names to different parts of the bone. Fig. 12, a, the pituitary fossa or sella turcica, a slight concavity in the centre of the bone for the lodgement of the pituitary body ; b, b, points having the name of the anterior; c, c, the posterior cli- noid processes, so called from their supposed resemblance to the knobs of a bedstead. An eminence in front, d, is called the olive-shaped process, upon which the optic nerves meet and unite; e, e, the optic foramina, through which these nerves and an artery pass to the eye. The points f f continued from the anterior clinoid processes, are the transverse processes, or the smaller wings. In front of the body is g, the ethmoidal spine; h, the basilar process, which joins the occipital bone : on each side of that process is a deep notch, forming part of the carotid foramen. Between the transverse spinous process and the temporal portion of the bone is /, i, the sphenoidal fissure, or foramen lacerum, which transmits the third, fourth, and sixth pairs of nerves, and the first branch of the fifth pair; behind and below is k, k, the round foramina, which trans- mits the second branch of the fifth pair of nerves ; Z, /, the oval foramina, through which pass the third branch of the OF THE HEAD. 27 fifth pair of nerves; m, m, the spinal foramina, by which the middle artery of the dura mater passes; n, n, the entrance of the pterygo-palatine canals, by which the pa- latine nerves pass to the mouth; o, o, the temporal por- tions, or plates, or the larger wings; q, q, the spinous processes. In the posterior view, Fig. 13, /,/, is a profile of the transverse processes ; i, i, the sphenoidal fissure; o, o, the temporal plates, or alae ; p, p, the smooth surfaces which constitute part of the orbit of the eye, the orbitar plates; q, q, the spi- nous processes; r, r, the external pterygoid processes; s, s, the in- ternal pterygoid pro- cesses, each of which terminates in a little curved process, called the hooklike process01, over this a tendon of the extensor muscle of the palate plays ; t, the azygos process; u, the body containing the sphenoidal cells : the lines point to their openings. There is a foramen at the base of each pterygoid pro- cess, called the vidian foramen, frpm Vidius, who disco- vered it. This transmits a nerve that does not go from the cavity of the cranium, but returns into it. The second branch of the fifth pair, after passing out of the cranium, sends back, through this foramen, a branch called the vi- dian, which, upon its arrival in the cranium, enters the temporal bone. The sphenoid bone is united by its ethmoidal spine to the nasal plate of the os ethmoides; by its transverse process and the orbitar plates to the os frontis ; and at the back part of its temporal to the sphenoidal angles of the ossa m Hamular process. 28 OSSEOUS SYSTEM parietalia: by the posterior edges of the same plates, and its spinous process, it joins the squamous portions of the temporal bones. From its spinous processes to the roots of the pterygoid processes, it touches the inferior angles of the petrous portions of the temporal bones; and by its basilar process it is connected with the sphenoidal process of the os occipitis : by the anterior edges of its orbitar plates it is united to the ossa malarum; by the anterior surfaces of its pterygoid plates to the ossa palati; and by the azygos process to the vomer. There are thirteen'pairs of muscles attached to the os sphenoides; viz. the levator palp ebr a superioris, the recti muscles of the eyes, the superior oblique muscle of the eyes ; the temporal and pterygoid muscles, buccinator, ex- ternus malei, constrictor pharyngis superior, and tensor palati. the ethmoid bone. Os ethmoides. Fig. 14, a side view; Fig. 15, a posterior; Fig. 16, an anterior view. The letters refer to the same parts in each figure. 14 15 16 The ethmoid bone derives its name from the upper surface resembling a sieve, being full of small holes; it is of a cubical form, and consists principally of numerous cells. a. The cribriform plate, perforated by numerous little holes" to transmit the olfactory nerves, or nerves of smelling, n Foramina cribrosa, from cribrum, a sieve. OF THE HEAD. 29 into the nostril. In the middle at b is a sharp process, the ethmoid crest0. From the lower part descends c, the nasal plate, making part of the central partition of the nose; d, the flat or orbitar plates?, which form the principal portions of the inside of the orbits. We see on each side of the nasal septum, e, e, the turbinated plates, thin, pen- dulous, and convex; and on the back part, this bone has numerous cells, f, f consisting of many convoluted plates of bone, called labyrinths, very deserving of an attentive examination, being perhaps the most curious bone of the human body. The nerves of smelling, after passing through the cribriform foramina, are expanded on the per- pendicular septum, and throughout the whole extent of the cells. A very considerable surface is thus provided for the distribution of the nerves, occupying little space. The ethmoid bone is joined by the edges of its cribriform plate to the ethmoidal notch of the os frontis, and to the os sphenoides ; and by the posterior part of its nasal plate to the latter bone, and to the vomer; by the fore part of the same plate to the back part of the nasal crista of the os frontis; by its anterior edge to the os lachrymale, and by the lower edge of the same plate to the superior maxillary bone. There are no muscles attached to or covering this bone. THE WORMIAN OR TRIANGULAR BONES. Ossa Wormiana, ossa triquetra. These are little irregular bones found in the course of the suture formed by the parietal and occipital bones, see Fig. 3, d, d: their existence is not constant. o Cri«tagaIIi. P Ossa plana. 30 OSSEOUS SYSTEM THE BONES OF THE FACE Are in pairs, except two bones, one of which forms part of the partition of the nose, the other is the lower jaw. The union of the bones of the face has been called su- tures, and named according to their connexion with each other ; but they are united rather by simple irregular lines, than by sutures. TH7/. NASAL BONES. Ossa nasi. Fig. 17, the external surface ; Fig. 18, the internal surface. These bones form the bridge of the nose ; they are convex externally, thereby giving greater resist- ance to violence from without; and they are concave internally for enlarging the cavity of the nose**; at their middle part each presents a small foramen which passes through the bone, and transmits a vein to the pituitary membrane. The superior margin of this bone is joined to the nasal process, and spine of the os frontis, and nasal plate of the os ethmoides; its external edge is received into the nasal process of the superior maxillary bone; its inner edge is united to its fellow, and its lower edge is joined only by the alar cartilages of the nose. There are two muscles attached to it, viz. the occipito- frontal, and compressor naris. q It has been stated that the inhabitants of Java, the Hottentots, and South-sea islanders, compress the nose immediately after birth, conceiving a broad nose conducive to beauty. OF THE FACE. 31 the lachrymal bones. Ossa lachrymalia. Fig. 19. This bone is nearly the size, shape, fand indeed thickness of the finger nail, there- ~° fore has the name also of os unguis. It is called lachrymal because a, the anterior con- cave portion, supports the lachrymal duct, which conveys the tears from the inner corner of the eye into the nose ; b, the orbitar plate, which assists in forming the orbit of the eye. the cheek bones. Ossa malarum. Fig. 20. The bone of the left side. Its several angles are named as follows: a, the superior orbitar process; b, the inferior orbitar process; c, the maxillary process; d, the zygomatic process. The concave surface, e, forms a portion of the orbit, called the internal orbitar process. There is but one foramen,/", the malar foramen, through which the malar nerve passes. The cheek bone is joined by its zygomatic process to the malar process of the temporal bone ; by its superior orbitar process to the external angle of the os frontis; by the posterior edge of its orbitar plate to the os sphe- noides ; and by the inner edge of the same plate to the os maxillare superius. There are four muscles attached to it; viz. obliquus inferior oculi, zygomaticus major and minor, masseter, and that of the orbicularis palpebrarum is extended over it. 32 OSSEOUS SYSTEM the upper jaw bones, ossa maxillaria supcrioraT. The superior maxillary bones constitute the principal part of the bones of the face. Fig. 21, the outer; Fig. 22, the inner view. The body of the bone is of an irre- gular form, having 21 22 a large cavity, a, opening into the nostrils, commonly called the antrum ofiHighmores. On the outer surface is b, the infra orbi- tar foramen, for the passage of the second branch of the fifth pair of nerves to the face; c, the malar process; d, the nasal process; e, a depression contributing to form the small cavity for lodging the lachrymal sac ; this cavity descends, and becomes at f part of the nasal duct. Between the malar and nasal processes, extending back- wards, is g, the orbitar plate. The posterior surface of the bone at i is rounded, therefore termed the tuberosity, the inner edge of which is rough, to join with the ptery- goid process of the os palati, forming with it the palato- maxillary canal. From the inner and lower part of the body extends horizontally h, the palatine process, forming the greater portion of the floor of the nose, and hollowed below, to form an equal part of the roof of the mouth. On the upper surface is a crest or ridge, which is grooved to receive the septum of the nose. Immediately behind the front teeth is the foramen incisivum ; the ductus inci- sivus is a continuation of this foramen between the palatine processes into the nose. There are usually eight alveolar cavities in each bone to receive the teeth. f Superior maxillary bones. s Sinus maxillaris. OF THE FACE. 33 The superior maxillary bone is united by its malar pro- cess to the inferior orbitar process of the os mala?; by its anterior inner edge to the os nasi, and on the inside to the os turbinatum; by the upper part to the os frontis, and the os lachrymale ; by the inner edge of its orbitar plate to the flat plate of the os ethmoides; by the poste- rior point of the same plate to the os palati. It is con- nected by its tuberosity, body, and palatine process with the same bone; by the inner edge of its palatine process with that of its fellow; and by the nasal crest with the vomer. There are ten muscles attached to this bone ; viz. the constrictor phuryngeus superior, pterygoideus externus, buccinator, masseter, levator anguli oris, levator and de- pressor labii superioris alaque nasi, orbicularis palpebra- rum, obliquus oculi inferior, and compressor naris. the palatine bones. Ossa palatina. Fig. 23. the anterior; Fig. 24, the posterior view of 23 24 tne palate bone. The letters refer to the same part in each fi- gure. This bone is placed at the lower and back part of the last de- scribed bone, and below the middle region of the base of the skull; a, the palatine process, wide at its outer edge to join its fellow; from the outer edge of the palatine rises up b, the nasal process, which forms a thin parti- tion between the cell of the superior maxillary bone and the nose ; it is marked internally by a strong ridge, to which the turbinated bone is attached: behind the nasal vol. i. 6 34 OSSEOUS SYSTEM . process, backwards and outwards at c, is a projecting point of bone, the pterygoid process; it has two grooves, one of which terminates in f the palato-maxillary fora- men, through which the palatine nerve and vessels pro- ceed to the palate. There is another small foramen near the last, marked g, the palatine foramen, to transmit branches of the same vessels and nerves to the soft palate. The upper part of this bone is divided by a notch into two portions, d, the sphenoidal process, which is united to the body of the sphenoidal bone; e, a small triangular portion, which, entering into the formation of the socket of the eye, is termed the orbitar process. The os palati is joined to its fellow by the palatine process; and by the nasal crest to the vomer; by the anterior part of the palatine process to the superior max- illary bone; by the ridge on the inside to the os turbina- tum; by the nasal and pterygoid processes to the body and tuberosity of the os maxillare superius; by its ptery- goid, sphenoidal, and orbitar processes, to the pterygoid process and body of the os sphenoides; and by its orbitar process to the same process of the os maxillare superius, and the flat plate of the ethmoidal bone. Five muscles are attached to, and connected with the os palati; viz. the buccinator, pterygoideus externus and internus, constrictor, pharyngeus superior, and azy- gos uvula. TURBINATED BONES. OsStt tlU'biiiata1. Fig. 25. Sometimes called the inferior spongy bones, to dis- tinguish them from the upper spongy bones, which belong 1 Ossa spongiosa inferiora. OF THE FACE. 35 to, and are a part of, the ethmoidal bone. They are pen- dent in the nostrils, curved, and exceedingly porous in 25 their texture. This bone is joined on the upper and on the outer side to the body of the superior maxillary bone ; anteriorly to the nasal process of the same bone, and to the os lachrymale; and posteriorly to the nasal process of the os palati. THE vomer. Fig. 26 is thus named from its shape resembling a ploughshare. It is divided into four edges, a, the sphenoidal, the broadest, and hollowed to receive the azygos pro- cess of the sphenoidal bone; b, the an- terior or nasal process, grooved to re- ceive the nasal plate of the ethmoid bone, and the carti- laginous septum of the nose ; c, the inferior or crista, uniting with the crest of the superior maxillary bone ; d, the posterior or pharyngeal margin, concave and facing the pharynx. 36 OSSEOUS SYSTEM the lower jaw. Os maxillare inferius. This is by far the largest bone in the face, but it is here divided, to shew to greater advantage the outer and inner surfaces. Fig. 27, 28. The letters refer to each, a, a, the basis, is the boundary of the face ; b, b, 27 28 A. ' OF THE TRUNK. 37 the angle; c, c, the ramus; d, the condyle; e, e, the coronoid process. Fig. 28, f the inferior maxillary foramen; nerves and vessels enter into this canal to sup- ply the teeth, and afterwards pass out at g, the mental foramen. There are the same number and kind of teeth in the lower as in the upper jaw, and consequently cavi- ties or alveoli to deceive them. The teeth may be reckoned aa follows, viz. (on each side of the jaw,) h, two incisors or cutting teeth ; i, one canine or dog tooth; k, two small molar; I, three large molar or grinding teethu. i, The lower jaw is connected by capsular and, lateral ligaments with the glenoid cavities of the ossa temporum, having an interarticular cartilage between them. There are twelve pairs of muscles attached to this bone; viz. externally, the masseteres, depressores an- guli oris, depressores et levatores labii infcrioris; inter- nally, the temporales, pterygoidei externi et interni, buccinatores, mylo-hyoidei, genio-hyoidei, digastrici, et genio-hyo-glossi: the platysma myoides passes over it. CHAP. III. THE BONES OF THE TRUNK. The trunk is composed of the spine or back bone, the thorax or chest, and the pelvis or hips. The spine, though spoken of as a single bone, consists of twenty-four bones, which turn or play upon each other, and hence have been called vertebra. The verte- bral column supports the trunk, head, and arms, and u The teeth will be particularly described at the end of the osseous system. 38 OSSEOUS SYSTEM admits of the turning and bending of the body; indeed, it has a movement in every direction : it forms a secure canal for conducting the delicate structure of the spinal marrow through its whole length ; and it is remarkable for combining those two opposite yet very essential quali- ties, strength and flexibility. The vetebrae are arranged into three classes, according to their situation. 1st. The cervical, or those of the neck, of which there are seven. 2nd. The dorsal, or those of the back, which are twelve. 3rd. The lumbar, or those of the loins, consisting of five bones. As a general description of a vertebra, each has a body, a large foramen to contain the spinal marrow, and several processes. By the junction of the processes and the bodies of the vetebrae, the canal is formed for the spinal marrow and its membranes. The roots of those processes, called the articular processes, are hollowed out above and below into notches ; these, when the vertebrae are fitted together, form apertures on each side of the spine, through which the nerves pass out from the spinal canal. THE VERTEBRiE OF THE NECK. These are smaller than the other vertebrae. Fig 29 is the third, selected as an example ; a, the body, is longest from side to side ; b, the spinous process, fork- ed ; c, c, the transverse processes, double, and having d, d, circular foramina, for the passage of the vertebral artery ; e, e, the superior; OF THE VERTEBRA. 39 f, f the inferior articular or oblique processes; g, the spinal foramen, large and triangular, and, as before stated, contributing to the formation of the canal for the spinal marrow. THE PECULIARITIES OF THE VERTEBRA OF THE NECK. d 31 FIRST VERTEBRA, OR ATLAS. The first vertebra, which, from its use in supporting the head, has the name of atlas, consists of a ring of bone, as we observe in Fig. 30, the upper, Fig. 31, the lower sur- „. face. As it receives the commencement of the spinal marrow, the opening a is (i large, and in place of the body at the front it is further hollowed out at b, for the reception of the dentiform process of the next vetebra ; c, c, the superior articular processes, irregularly oval, and concave; these ar- ticulate with corres- ponding processes of the skull, by which the head has the power of bending backward and forward. In Fig. 31, we observe e, e, the inferior articular surfaces, are flat, and thus adapted to the superior articular surfaces of the adjoining vertebra, allowing of a horizontal motion of the head; d, d, the trans- verse processes, broad, a little forked, and perforated. 40 OSSEOUS SYSTEM THE SECOND VERTEBRA, OR DENTATAV. The most remarkable characteristic of this vertebra is a, a projecting point called the tooth-like processw, which rises from the upper part of the body, and has an articulating surface on its front, which is ([ received into the hol- low of the atlas. Fig. 32, b, b, the superior articular processes of the dentata, are flat, for on these planes the atlas rotates ; c, c, the inferior ar- ticular processes; d, d, the transverse processes, small and single: the foramina in them are not perpendicular, but pass upwards and outwards, and the spinal foramen is large. Thus two distinct motions are perfectly accomplished, without interfering with each other. When we nod the head, we use the joint between the head and the first bone of the neck ; when we turn the head round, we use the pivot joint formed by the dentata and atlas. T Named dentata from its projecting tooth-like process, a. w Processus dentatus. 1047 OF THE VERTEBRA. 41 Fig. others 33 THE SEVENTH VERTEBRA OF THE NECK. 33. The seventh vertebra is larger than the it resembles in form the third, which has been given as an example and general description of a cervical vertebra. In this before us, neither a, a, the transverse processes, nor c, the spinous process, are double; but the latter is so much longer than the others, that this bone has obtained the name of ver- tebra prominens. THE VERTEBRiE OF THE BACK. Fig. 34. The twelve vertebrae particularly belonging to the back are termed dorsal. They are named in nume- 34 rical order, and diminish in size from the first to the fourth, from which they increase to the twelfth, which is the largest: a, the body, is longer from front to back, than trans- versely ; b, the superior, c, the inferior articular surface. The body somewhat flattened on either side presents small semicircular depres- sions, d, e, for receiving the heads of the ribs : f the superior articular process, vertical, and directed back- vol. t. 7 42 OSSEOUS SYSTEM wards ; g, the inferior articular process, directed forwards ; h, the transverse process, thicker as it extends backwards; L the spinous process, long and inclining downwards; ;, the notch under which pass the nerves of the spinal chord. THE VERTEBRA OF THE LOINS. Fig. 35, 36. We have here two views of a vertebra of the loins1; the lumbar vertebrae are the lowest five of the spine : a, a, their bodies, though of a circular form in front, are somewhat oblong from side to side, and larger, and of a more spongy texture, than any of the other clas- ses : b, b, b, the supe- rior ; c, c, c, the infe- rior articular proces- ses, strong and deep: the superior, concave; the inferior, convex; d, d, d, the transverse processes, are small and long ; these, like bony processes in ge- neral, serve as levers for the moving pow- ers; e, e, the spinous processes, strong, ho- x Vertebra lumbaris. OF THE VERTEBRAE. 43 rizontal, and flattened at the sides; /, the spinal foramen. Numerous muscles are attached to the back part of the spine, viz. the trapezii, latissimi dorsi, rhomboidei ma- jores et minores, levatores scapula, serrati postici supe- riors et inferiores, splenii, complexi, sacro lumbales, cervicales descendentes, trachelo mastoidei, longissimi dorsi, transversales colli, spinales et semispinales colli, recti capitis postici majores et minores, obliqui capiti su- periors et inferiores, multifidi spina, inter spinales, in- tertransversales, et levatores costarum; on the fore part, longi colli, recti capitis interni majores et minores, recti capitis laterales, scaleni antici, medii, et postici, dia- phragma, quadrati lumborum, psoa magni et parvi, ob- liqui interni, et transversales abdominis. GENERAL OBSERVATIONS ON THE SPINE. The twenty-four vertebrae?, united by an elastic sub- stance, form the spine, or vertebral column: their volume is very considerable in the lumbar region, but decreasing in size as they ascend to the head, though with some irre- gularity : it is a pyramid, reposing its base on the sacrum, as a sort of pedestal, and having on its summit the head. The spine in front appears perpendicular; a lateral view presents a waved line, having a very near approach to Hogarth's line of beauty. Altogether, the structure of the vertebral column is admirable, so that after an atten- tive examination we are not surprised that all writers on natural theology should have selected this part of animal bodies as a specimen of the most exquisite mechanism2. ' y If we find a separate vertebra, we may know to which class it belongs by the following rule, viz. the peculiar characteristic of a cervical vertebra is the perforations in the trans- verse processes. The dorsal are distinguished by having articular surfaces for the heads of the ribs. The lumbar by their size, and the length of the transverse processes. z See Paxton's Paley's Nat. Theol. ch. viii.; Derham's Phys. Theol. ch. viii. 44 OSSEOUS SYSTEM THE RIBS, COSta, Are placed on each side of the vertebrae of the back, and with them form the posterior and lateral parts of the chest. They are commonly divided into seven true and five false, or into sterno-vertebral and vertebral: of these, the sterno-vertebral or true ribs, the seven superior, are united by means of a portion of cartilagea directly with the sternum; the vertebral or false ribs, the five inferior, are either joined by their cartilages to each other, or, as we see in the two lowermost, are totally unconnected with the sternum, and are sometimes called loose or floating ribs. The fourth rib is here taken for general description. * Fig. 37, the lower; Fig. 38, the upper edge. It is flat within and without. The vertebral extremity, a, a, is called the head, which has an articular surface divided by a middle ridge to articulate with the bodies of the two contiguous dorsal vertebrae. The bone at b, b, is con- tracted, forming the neck; at the back of the rib is c, c, a Gristle. OF THE RIBS. 45 the tubercle, having a plain articular surface for the trans- verse process of the vertebra ; further outward the bone suddenly bends forward, producing d, d, the angle, from which proceeds the body, which in its natural situation passes forwards and downwards to e, e, the sternal ex- tremity, where it has a slight oval concavity to which the cartilage adheres, and which cartilage joins the rib to the sternum or breast bone. At the under edge of each rib we find, Fig. 37, f a groove for the intercostal vessels and nerves. From the first to the seventh pair, the ribs increase in length; this gives the chest its conical shape : from the seventh they begin to decrease in length to the twelfth, which is as short as the first: and with regard to the direction of their inclination, that of the first is nearly ho- rizontal, whilst the lower ones dip down more and more at their points. But there are other remarkable distinc- tions in the first, eleventh, and twelfth ribs—as THE FIRST RIB. Fig. 39. The first rib is very short, and much curved. 46 OSSEOUS SYSTEM THE ELEVENTH AND TWELFTH RIBS. Fig. 40. is the twelfth rib; the eleventh is like it, only a little longer. They do 40 not articulate with the transverse processes of the vertebrae, and are uncon- nected with the breast bone. These ribs are much shorter than all the others, except the first; their heads have only single articular surfaces to join with the whole articular cavities of the two lowest dorsal vertebrae. The muscles attached to the ribs are ; the pectoral majores et minores, subclavii, sterno thyroidei, scaleni antici, medii, et postici, latissimi dorsi, serrati majores antici, superiores et' inferiores postici, sacro lumbales, accessorei ad sacro lumbalem, longissimi dorsi, levatores et depressores costarum, intercostales, sterno costalis, dia- phragma, obliqui externi et interni, transversales, et recti abdominis, et quadrati lumborum. THE BREAST BONE. The situation of the sternum or breast bone is well known. It is connected with the cartilages of the ribs, and with the collar bones, and is usually divided into two or three parts. In the position before us, Fig. 41, it con- OF THE STERNUM. 47 sists of two bones. The first is broad and thick above, and a little contracting as it descends. It is irregularly convex before, and concave behind. At the upper angle, a, the collar bone, is articu- lated ; b, the articular sur- face for the cartilage of the first rib; c, the depression, which, with the depression of the second bone, form an articular surface for the car- tilage of the second rib : d, e,fg, mark the concave ar- ticular surfaces of the third, fourth, fifth, sixth, and se- venth ribs; g, points to the two last depressions of arti- culation, which are contiguous. There are transverse lines on the lower bone, which indicate its further division in early life. h. The ensiform cartilage, terminates the lower extre- mity in the sternum. In the adult it is frequently ossified. The sternum, ribs, and dorsal vertebrae, form the bones of the chest or thorax, the offices and uses of which are multiplied ; for it is the centre of motion for directing the animated machine, protects the heart, lungs, and other important parts ; but its agency in respiration must be considered its most important function. The muscles attached to the sternum are the pectorales majores, sterno- cleido mastoidei, sterno hyoidei, sterno thyroidei, et in- tercostales interni. 48 OSSEOUS SYSTEM THE BONES OF THE PELVIS. The large bony cavity situated at the lowest part of the trunk, by which its weight is transferred to the lower extremities, is called the basin or pelvis; for it in part contains and supports the bowels and other viscera. It consists of a pair and two or more single bones. unnamed bones. Ossa innominata. The two large, broad, and irregularly shaped bones called ossa innominata or hip bones, constitute the fore part and sides of the bason, and the lower part of the sides of the abdomen—the upper edge is frequently called the hip. Each bone is usually described as three bones, from its having been composed of three distinct pieces in the first period of life: these portions retain the same name though united in one solid broad bone. To obtain there- fore a knowledge of the terms employed in this description, we must advert to its original construc- tion. Fig. 42 shews the three portions united by cartilage: a, the ilium; b, the ischium; c, the os pubis; the subsequent description will have a reference to these terms. OF THE PELVIS. 43 49 44 VOL. I. 50 OSSEOUS SYSTEM Fig. 43, the outer surface of the hip bone or os inno- minatum; Fig. 44, the inner surface. The letters refer to each view: a, the back of the ilium; b, the crest; c, the anterior superior spinous process ; d, the anterior inferior spinous process; e, e, the posterior superior and inferior spinous processes; f, the fifth spinous process, but is dis- tinguished by the term of the ischium; g, the greater ischiatic notch. The inner surface, h, of the os innomi- natum, or rather that portion of it called the ilium, is concave and smooth; i, an elevated line, the linea inno- minata, which, when joined to its fellow, forms part of the brim of the pelvis ; j, a large uneven articular sur- face for the sacrum ; k, a large and deep hollow, the socket for the head of the thigh bone, called the acetabulum, from its resemblance to a measuring cup used by the ancients. The margin is not perfectly circular, but ap- pears deficient at the under part, forming a notch, which in the recent subject is filled up with ligament to complete the edge of the cup. In the centre of this cavity, and continued to the notch is a depression, to which the round ligament of the thigh bone is fixed; /, the lesser ischiatic notch; m, the tuberosity of the ischium; o, the ramus of the pubis; p, the pubis; q, the obturator foramen. The muscles attached to and covering the os innominatum, are the psoas magnus et parvus, iliacus, levator ani, obturator internus, pyriformis, coccygeus, obliquus externus et inter- nus, transversalis, rectus, et pyramidalis abdominis, quad- raius lumborum, longissimus dorsi, sacro lumbalis, et latissi- mus dorsi, tensor vagina femoris, sartorius, gluteus maxi- mus, medius, et minimus, rectus femoris, gcmini, quad- ratus femoris, biceps flexor cruris, semitendinosus et semi- membranosus, transversus perinai et transversus perinai alter, ischiocavernosus, levator ani, triceps adductor femo- ris, gracilis, pectineus, et obturator externus. OF THE PELVIS. 51 OS SACRUM. 45 Fig. 45. The sacrum is the basis which supports the vertebral column. The sacrum is placed between the ossa in- nominata, to form the posterior part of the cavity of the pelvis. On the front and con- cave surface are four lines, indicating the junction of the differ- ent pieces of which it is composed during infancy1". Here we have a posterior view of the adult bone; a, the part with which the body of J;he last vertebra of the loins articulates , b, b, the articular pro- cesses, which correspond with the inferior articular pro- cesses of the lowest vertebra of the loins; c, c, the upper- most of eight foramina, called the posterior sacral foramina, for the passage of small nerves and vessels. Between these are four eminences, short and horizontal, forming a continuation of the line of spinous processes of the ver- tebrae. Above is the commencement of the sacral canal, terminating below atg; this canal receives the extremity of the spinal marrow, which in this situation is exceedingly fibrous, and from the nearly parallel disposition of the nerves that issue from it has obtained the name of cauda equina, b These have been called the false vertebrae. 52 OSSEOUS SYSTEM or horse's tail; d, d, the lateral surfaces, irregular and rough, articulating with the hip bones; e, an oval surface uniting with the os coccygis. The muscles attached to the sacrum are the longissimi dorsi, sacro lumbales, multifidi spina, glutei maximi, pyriformes, et coccygei. the coccyx. Os coccygis0. The os coccygis, f Fig. 45, is divided into several bones which are appended to the sacrum; and although in ad- vanced age it is one solid bone,* yet in the prime of life, as is represented in the present instance, it consists of four distinct bones. The upper one is united to the sacrum by a flat surface, on each side of which are projections called the cornua. The only muscles attached to this bone are the coccygei. CHAP. III. THE BONES OF THE UPPER EXTREMITY. The npper extremity consists of the collar bone, the shoulder blade, the arm, the fore arm, and the hand. THE COLLAR BONE, daVlCula, Termed clavicle from its resemblance to an ancient key, has a body and two extremities. Fig. 46, a, the sternal e So called from its figure being somewhat like a cuckoo's beak. OF THE UPPER EXTREMITY. 53 extremity, presenting a triangular surface for its articula- tion, by means of an intervening cartilage, to the sternum; b, the rhomboid process; c, the tubercle; d, the scapular extremity, which is the flattest part of the bone, and has a narrow articular surface for the acromion of the scapula. The muscles attached to the clavicle are six ; to its un- der part trie pectoralis major, deltoides, and subclavius; and to its upper part, the trapezius, sterno-cleido-mastoi- deus, and sterno-hyoideus. The clavicle tends to puevent the arm from falling for- ward on the breast; and increases the sphere of action of the arm, by enabling it to describe a circle, the centre of which is the connexion of the clavicle with the shoulder. THE SHOULDER BLADE. Scapula. The scapula or shoulder blade is situated on the back and upper part of the ribs, and forms the posterior part of the shoulder. Its form is an irregular triangle ; it is flat, and so very thin as to be transparent in its greatest ex- tent. This bone is retained in its situation merely by muscles that unite it to the head, the os hyoides, the ribs, the vertebrae, and the upper arm bone ; by means of these muscles it consequently has the power of moving upwards, downwards, backwards, and forwards; and by a quick suc- cession of these motions the arm is rotated. Thus the scapula serves not only as a support, but a fulcrum for every action of the superior extremity. Fig. 47, the front; Fig. 48, the back view. 54 m 4^ OSSEOUS SYSTEM 47. 48. a h .—m The scapula is usually described with reference, «o,£ triangular figure ; ., ., the »p.mr angle; b, b, the «fi OF THE UPPER EXTREMITY. 55 rior angle; c, the outer angle, having an oval concave articular surface; d, d, the glenoid cavity, or socket in which the head of the arm bone is articulated ; around which the bone becomes contracted at e, e, forming the neck. The sides of the triangle are thus denominated: f f the basis; g, g, the inferior border or costa; h, h, the superior border; i, the fossa for the attachment of the infra-spinatus muscle : k, the fossa for the attachment of the supra-spinatus muscle ; /, I, the commencement and course of the spine, terminating in a flat projection ; m, m, the acromion^, which we see extended over the glenoid cavity, protecting the joint, and forming the point of the shoulder to which the collar bone is articulated. There is another projection, n, n, compared to the beak of a crow, therefore termed the coracoid process ; this also guards the shoulder joint, and with the acromion gives advantageous points of attachment to muscles which move the arm. Between the coracoid process and the superior border is o, o, an indentation, the semilunar notch, which is formed into a foramen by a ligament, and affords a passage for the supra-scapular artery, vein, and nerve. The muscles attached to this bone are sixteen in num- ber ; viz. to the spine above, the trapezius, and below, the deltoides ; to the base, the levator scapula, rhomboi- deus minor et major, and serratus magnus; to the notch in the superior border, the omo-hyoideus ; to the foss, the supra spinatus, infra spinatus, and subscapulars; to the inferior border, the teres minor, and the long head of the triceps extensor cubiti; to the inferior angle, the teres major; and to the coracoid process, the coraco-brachialis, pectoralis minor, and the short head of the biceps flexor cubiti, the long head of which muscle has an attachment to the glenoid cavity. d The point of the shoulder. 56 OSSEOUS SYSTEM 49. a 50. a the upper arm. Os brachii. The upper arm consists of a single bone, called also os humeri. Fig. 49 represents the back, Fig. 50 the front view ; a, a, the head, is hemispherical, stan- ing obliquely back- wards from the bone, and when received in- to the glenoid cavity of the scapula consti- tutes a ball and socket joint; b, the smaller tubercle; c, the great- er tubercle ; they are separated by e, a chan- nel^ in which the ten- don of the long head of the biceps muscle plays. The bone is contracted at d, d, and forms the neck. The body of the bone is nearly cylindrical.— The lower extremity of the bone is flatten- ed, and constitutes with the ulna a perfect hinge joint; /, the outer condyle; g, g, the inner condyle, more projecting than the outer, as it gives attachment to the flexor muscles of the fingers. The lowest part of the bone has two articular surfaces: that on the outside, h, convex, for the head of the radius; that on the inside, i, concave from side to side, but convex • The bicipital groove. OF THE UPPER EXTREMITY. 57 from back to front, for the reception of the sigmoid cavity of the ulna. Above the articulation, and in front, Fig. 49, there is a depression for the coronoid process of the ulna. Behind, Fig. 50, is another depression for the olecranon of the ulna; j, the foramen for the medullary artery, which supplies the circulation of blood to the marrow of the bone. There are twenty-four muscles attached to the os hu- meri ; viz. the deltoides, supra spinatus, infra spinatus, teres minor, subscapularis, pectoralis major, latissimus dorsi, teres major, coraco brachialis, triceps extensor cubiti, brachialis internus, palmaris longus, flexor carpi radiaJis, flexor carpi ulnaris, flexor digitorum sublimis perforatus, flexor longus pollicis, pronator radii teres, supinator radii longus et brevis, extensor carpi radialis longior et brevior, extensor carpi ulnaris, extensor digito- rum communis, and anconeus. THE FORE ARM Consists of two bones, the ulna and radius. VOL. I. 9 58 OSSEOUS SYSTEM THE ULNA OR LARGER BONE OF THE FORE ARM. Fig. 51. The ulna is placed on the inside of the fore arm by the side of the radius. The upper extremity is large and scooped out in front, a, forming the 51 greater sigmoid cavity; this is the cavity which articulates with the base of the os humeri. Below, this appa- rent excavation is bounded by b, the coronoid process, above, by e, the ole- cranon, or elbow ; this point serves as a lever for the extensors of the fore arm. There is a smaller concave ar- ticular surface for the head of the radi- us at c, the lessor sigmoid cavity ; d, a small eminence, called the tubercle. The body or shaft of this bone is strongly marked by muscles, and by the ligament interposed between the bones. The lower end has a rounded articular surface, f for the radius, and beneath a shallow cavity for an inter- fl^—..../• articular cartilage, the medium of con- nection with the wrist. On the inside, g its lengthened point, g, forms the styloid process. There are fourteen muscles attached to the ulna; viz the brachialis internus, triceps extensor cubiti, anconeus, pronator radii teres, flexor carpi radialis, flexor carpi ulnaris, flexor digitorum communis, sublimis, et profun- dus, pronator quadratus, extensor carpi ulnaris, extensor ossismetacarpi pollicis, extensor primi internodii pollicis, and indicator. OF THE UPPER EXTREMITY. 59 THE RADIUS. The radius, or smaller bone of the arm, is supposed to be so named from its imaginary resem- ^ ' blance to the spoke of a wheel, or to a measure used by the ancients. It is . placed on the outside of the fore arm; 7 a, the body of the bone, inclines to a triangular form ; b, the upper extrem- ity, or head, presents a circular cavity, articulating with the smaller condyle of the humerus; its circumference' joins with, and turns in the smaller sigmoid cavity of the ulna; below, at c, the bone is contracted, forming a neck, which terminates in d, the bicipi- tal tubercle, to which is fixed the bi- ceps muscle. The lower end has e, a superficial cavity, articulating with the scaphoid and semilunar bones of the wrist. On the inner side there is a narrow concavity, in which the lower extremity of the ulna rotates. The extreme point, f is termed the styloid process. There are eight muscles attached to the radius; viz. the supinator radii longus et brevis, pronator teres et quadratus, biceps flexor cubiti, flexor digitorum communis sublimis, flexor longus, extensor ossis metacarpi pollicis. Paley has not passed unobserved the remarkable me- chanical contrivance of the fore arm. For the perfect use of the fore arm two motions are wanted ; a motion at the elbow backward and forward, which is called a reciprocal 60 OSSEOUS SYSTEM motion; and a rotatory motion, by which the palm of the hand, as occasion requires, may be turned upward. How is this managed ? The fore arm consists of two bones lying along side each other, but touching only near the ends. One, and only one, of these bones is joined to the humerus at the elbow; the other alone to the wrist. The first, at the elbow, by means of a hinge joint, which allows of motion in the same plane, swings backward and forward, carrying along with it the other bone, and the whole fore arm. In the mean time, as often as there is occasion to turn the palm upward, the bone to which the hand is at- tached, rolls upon the first, by the help of a groove or hol- low near the end of one bone, to which is fitted a corres- ponding prominence in the other. The first is at liberty at one end, the second at the other; by which means two actions may be performed to- gether. The os brachii may be swinging with its hinge joint at the elbow, at the very time that the radius which carries the hand, may be turning round in its groove. the hand. The last division of the superior extremity is the hand; it includes the wrist, the palm of the hand, and the fingers. the bones of the wrist. Carpus. The wrist or carpus consists of eight small bones dis- posed in two rows, forming an arch supported by liga- ments. Fig. 53 is the back of the wrist, (as the shape of OF THE UPPER EXTREMITY. 61 the several bones are best seen in this di- rection) ; a, the boat- shaped or scaphoid bone ; b, the half- moon or semi-lunar bone ; c, the wedge- like ovcuneiformhone; d, the pisiform bone, from its size and fig- ure resembling a large pea. In the second range we ob- serve on the outside, c, the trapezium; f the trapezoid bone : these two last are named from their figure; g, the large bone, os magnum; h, the unciform bone, named from its hook-like process, which projects into the hand. From the figure before us we may form a tolerably correct idea of their union and arrangement: on the back of the hand the wrist bones are convex, in front concave, the arch giving additional strength, while the projecting pisiform bone and unciform process increase the concavity for the passage of the flexor tendons of the fingers. The bones of the carpus have a gentle motion on each other, and on the fingers ; they also admit of a limited motion in every direction with the bones of the arm. There are two muscles attached to the os pisiforme ; viz. the flexor carpi ulnaris, and abductor minimi digiti: to the trapezium four; viz. the flexor ossis metacarpi pollicis, abductor pollicis, abductor indicis, and extensor ossis metacarpi pollicis. The only muscle attached to the trapezoid bone is the flexor brevis pollicis. To the os magnum also the same muscle is attached. The mus- cles inserted into the unciform bone are three; viz. the flexor brevis pollicis, flexor proprius pollicis, and abductor minimi digiti. h g f 62 OSSEOUS SYSTEM THE BONES OF THE PALM OF THE HAND. Metacarpus. 54. The bones called the metacarpus, Fig. 54, form the palm and back of the hand ; they sustain the fingers. We observe each bone long and rounded, the ends larger than the bodies. Their upper ends have plane sur- faces to unite with the carpus ; and where the metacarpal bones are contiguous to each other, they have also flat articular surfa- ces ; their lower ends articulate with the fingers by convex heads, to allow of a free motion in every direction ; we have at this joint a lateral motion, as well as flexion and extension1". There are eleven muscles attached to the metacarpal bones, viz. seven interossei, common to all; to that of the fore finger, the flexor carpi radialis and extensor carpi radialis longior; to that of the middle finger, the extensor carpi radialis brevior; and to that of the little finger, the extensor carpi ulnaris. f Those anatomists who reckon five metacarpal bones include the first bone of the thumb. OF THE UPPER EXTREMITY. 63 the bones of the fingers. Phalanges digitorum. 55. Fig. 55. The fin- gers consist of twelve bones, arranged in three rows, termed phalanges. They are rounded on the back, as we see in this fig- ure, but flat and some- what concave in front, as may be observed in Fig. 56. The first phalanx or row, a, a, has soc- kets at the superior extremities to articu- late with the metacarpal bones; the inferior extremity is convex from back to front, concave from side to side. The second phalanx, b, b, has on the upper ends con- cave articular surfaces, with a little rising in the middle, dividing it into two smaller concavities, adapted to the lower extremities of the first phalanx. The lower ends of the second phalanx are similar to the lower ends of the first. The third phalanx, c, c, has a joint similar to the se- cond ; their points are rough in front, but rounded at their backs to receive the nails. There are eighteen muscles attached to the phalanges, or finger bones; viz. in front, the flexor brevis digitorum sublimis, et profundus, flexor longus, et brevis, abductor, 64 OSSEOUS SYSTEM et abductor indicis, flexor proprius, et abductor minimi digiti, four lumbricales, and seven inter-ossei. At the back the extensor digitorum communis and indicator. THE BONES OF THE THUMB. The bones of the thumb, Fig. 56, a, b, c, very much resemble the bones of the fingers ; but as the thumb is the antagonist of the fingers, it is much thicker and stronger. The first bone is connected by a double articular sur- face to the trapezium. The muscles attached to the front of the thumb are the flexor brevis et flexor ossis metacarpi pollicis, and abductor indicis; to the back of the thumb the extensor primi internodii pollicis. OF THE LOWER EXTREMITY. 65 Fig. 57, a front view of the bones of the hand. 57. CHAP. IV. THE BONES OF THE LOWER EXTREMITY. The lower extremity consists of the thigh, leg, and foot. THE THIGH BONE. Os femoris. The thigh has one bone; it is the longest of the human skeleton, and it is as remarkable for its strength, support- ing the whole trunk and upper extremities, and often with the addition of burdens greater than the weight of the body itself. This bone is placed obliquely^, from the great g See Tab. i, if. VOL. I. 10 66 OSSEOUS SYSTEM M. breadth of the pelvis; and this obliquity of the shaft of the bone is necessary to bring it more immediately under the centre of gravity, and to render our steps not only more direct, but more quick and secureh. 59. I m, n p o h " Whilst a man stands on both his legs, the thigh bones are oblique to the gravitation of the body; but when one foot is raised, the whole body being then balanced on one foot, a change lakes place in the position of the thigh bone, and the obliquity of that bone is dinii nished; or in other words, now that it has the whole weight to sustain, it is perpendicular under it, and has therefore acquired greater strength." Jlnimal Mechaivics. OF THE LOWER EXTREMITY. 67 Fig. 58 the front, Fig. 59 the back of the femur or thigh bone ; a, a, the head of the bone, forming the greater por- tion of the sphere ; it articulates with the hip, and is the most complete instance of the ball and socket joint that we can produce. Besides a surrounding ligament, common to all joints, it has an additional security in a short, strong, yet flexible ligament, inserted by one end into the ball, at the depression, b, b, by the other end into a cup, or ace- tabulum of the hip bone; c, c, the neck; d, d, a large process, called the trochanter major; e, e, a smaller pro- jection, the trochanter minor. The curved line at/, Fig. 59, the linea quadrata, extending from one trochanter to the other, shows the attachment of the capsular ligament, and the quadratus femoris ; g, g, the body of the bone ; h, h, a long, rough, elevated line, the linea aspera; i, i, the outer, k, k, the inner condyle; these have four arti- cular surfaces: I, m, the two upper on the fore part, for the patella or kneepan ; n, o, the two lower, for the large bone of the leg. The latter articular surfaces are sepa- rated by p, a deep recess, into which the cross ligaments are inserted; it also affords protection to the large vessels and nerves passing to the leg. The medullary artery en- ters at q, about the middle of the bone. There are nineteen muscles attached to this bone, viz. the gluteus medius et minimus to the trochanter major; the psoas magnus and iliacus internus to the trochanter minor; the quadratus to the linea quadrata; the obturator internus et externus, gemini, and pyriformis, to the fossa trochanterica; the gluteus maximus, pcctineus, and triceps femoris, vasti, and biceps flexor cruris, to the linea as- pera ; the gastrocnemii, plantaris, and popliteus, to the condyles; the crureus, sartorious, gracilis, and tensor vagina femoris, are situated on the fore part of the femur, but are not adherent to it. 68 OSSEOUS SYSTEM the knee pan. Patella. The small round bone at the knee is called patella; it is situated at the front of the knee joint.— Fig. 60, the anterior surface, convex and rough from the adhe- sion of the fibres of a tendon which is spread over it. Fig. 64, the posterior surface, which indeed is divided by a perpendicular ridge into two slightly concave articular surfaces. This bone gives to the tendons which bring-forward the leg a very considerable mechanical ad- vantage, by altering the line of their direction, and by advancing it farther out from the centre of motion, and this upon the principles of the resolutions of force, upon which principles all machinery is founded. OF THE LOWER EXTREMITY. 69 THE shin bone. Tibia. The tibia is the large bone of the leg, situated at the inner side; Fig. 62, the front; Fig. 63, the side view. a, the head, having two semicircular arti- cular concavities, b, b, b, for the condyles of the thigh bone ; these concavities are sepa- rated by c, c, a mid- dle ridge or spine, to which the cross liga- ments of the knee are secured ; d, d, the tubercle which gives attachment to the li- gament of the patella; e, e, a small articular surface for the head of the fibula or small bone of the leg; f, f the spine or shin ; g, the outer side of the base, having i, a de- ^ * pression, or articular surface for the lower extremity of the fibula; h, the inner ankle, called the inner malleolus, on the under and back part of which is a groove, for the passage of the tendon of the tibialis posticus muscle; k, k, the surface for connect- ing it with the astragalus, or bone of the foot; I, the fora- men for the medullary artery. There are ten muscles attached to the tibia, viz. the sartorius, gracilis, and semitendinosus, immediately below 70 OSSEOUS SYSTEM the tubercle ; the semimembranosus, to the back part of the head of this bone ; the popliteus, soleus, tibialis posticus, and flexor longus digitorum pedis, to the back part of its head and body; the tibialis anticus and extensor longus digitorum pedis, are situated on the fore part of its head and body. THE SPLINT BONE. Fibula. Fig. 64. The small bone of the leg is called fibula, from its resemblance to the pin of a brooch; it is placed on the outside of the leg; the shape of ^ the bone is irregularly triangular; a, 0 the head or upper extremity : it has a smooth articular surface at b, on its inner side, to join with the tibia. The body presents several ridges and de- pressions for the lodgment and attach- ment of muscles; c, the inferior ex- tremity, lengthened to form the outer ankle, or external malleolus; d, an oblique articular surface, for the out- side of the astragalus. The ankle joint is strengthened and defended from injuries by those re- markable prolongations of the tibia and fibula which we name the external and internal malleoli, the outer and inner ankle. If the joint is in danger of dis- location outward, it is curbed by the d inner projection, i.e. that of the tibia ; if inward, by the outer projection, i.e. that of the fibula; between both it is locked in its position. Eight muscles are inserted into this bone, viz. to the upper extremity the biceps flexor cruris; to the fore parts OF THE LOWER EXTREMITY. 71 of its body the extensor longus digitorum and extensor proprius pollicis pedis; on the outside the peroneus lon- gus et brevis; and behind, the soleus, tibialis posticus, and flexor longus pollicis pedis. THE BONES OF THE FOOT. 65. Fig. 65 is a general view of the skeleton of the foot, which consists of twenty-six bones : d, e, f g, h, and two intervening bones, called the tarsus or instep ; a, the metatarsus or middle row of bones of the foot; and b, c, i, the three phalanges of the toes. The bones of the foot somewhat resemble the hand, but they are stronger, larger, and less calculated for motion. BONES OF THE TARSUS. The tarsus or instep consists of seven bones, and when joined they form an arch, under which tendons, vessels, and nerves pass into the sole of the foot. 72 OSSEOUS SYSTEM THE ASTRAGALUS. Fig. 66. 1st. The astragalus, so called from its resemblance to an ancient die; or rather, I am inclined to think, be- cause a game of dice was played with the talus or huc- ble bone of animals, to which this corresponds, a, a large c articular surface: above, it is convex from front to back, forming its largest articular surface for the base of the tibia; b, the articular surface for the lower extremity of the fibula: on the opposite side is a surface for articulating with the inner malleolus ; the fore part of the bone, c, is rounded, to articulate with the scaphoid bone; the under part, d, rests on the heel bone by two articular surfaces, separated by a deep groove. The only muscle attached to this bone is the tibialis posticus. THE HEEL BONE. Os Calds. Fig. 67 2d. The os calcis is the largest bone of the foot; a, the tube- rosity or heel; on the fore part are two ar- ticular surfaces, at b, c, for the astragalus; d, an articular surface for the cuboid bone. There are eleven muscles attached to the os calcis, viz. OF THE LOWER EXTREMITY. 73 to the upper part, the extensor brevis digitorum pedis; to the under part, the abductor, flexor brevis, abductor pol- licis pedis, flexor brevis digitorum, flexor digitorum acces- sorius, and abductor minimi digiti pedis; posteriorly, the gastrocnemii, soleus, and plantaris. • the scaphoid, or navicular bone. 3rd. The os scaphoides, or boat-shaped bone, is placed on the inner part of the foot, before the astragalus; at b Fig. 68. Fig. 69. it is concave, to articulate with that bone; in front, at a, its general aspect is convex, but its convexity is divided into three flat articular surfaces, for the three cuneiform bones. See Fig. 69, a, b, c. The tibialis posticus muscle is attached to this bone. THE CUNEIFORM BONES. The cuneiform or wedge-like bones are three in num- ber, denominated from their position the inner, the middle, and the outer cuneiform bones. They are applied to each other like the stones of an arch. VOL. T. 11 74 OSSEOUS SYSTEM THE INNER CUNEIFORM BONE. 4th. This bone is the largest of the three; it has four articular surfaces: one behind, to form part of the articu- lation for the scaphoid bone; another before, with a plain articular surface for the metatarsal bone of the great toe : its outer surface, i.e. the side towards the centre of the foot, has a flat articular surface for the lg' ' middle wedge-like bone, and a smaller surface for the metatarsal bone of the second toe; posteriorly, the three cunei- form bones form a cup, into which is received the rounded articular surface of the scaphoid bone; anteriorly, they join with the three large metatarsal bones, and, in consequence of the short- ness of the middle cuneiform bone, they are locked toge- ther like a mortice and tenon. The middle bone articulates on the inside with the inner, and on the outside with the outer cuneiform bones ; and the outer cuneiform is con- nected by its outer surface with the cuboid bone. There are five muscles attached to these bones, viz. to the inner, the tibialis anticus and peroneus longus ; to the outer, the flexor brevis and abductor pollicis pedis; and the tibialis posticus to all three bones. THE MIDDLE CUNEIFORM BONE. 5th. This is the smallest of the cuneiform bones; it has four articular surfaces: one behind for the scaphoid bone, one before for the metatarsal bone of the second toe, and one on each side for the first and third cuneiform bones. OF THE LOWER EXTREMITY. 75 THE OUTER CUNEIFORM BONE. This bone has five articular surfaces: one behind for the scaphoid, one before for the third metatarsal bone, two for the inside, i.e. for the middle cuneiform and second meta- tarsal, and one on the outer surface for the cuboid bone. the cuboid bone. Os cuboides. Fig. 73. 7th. Though this bone is so named from its shape, it is a very irregular cube: it has three articular surfaces, a, the largest of which, is posterior, and connected to the os calcis; b, the anterior, for the fourth and fifth meta- tarsal bones ; the smallest is articulated on the inner surface to the scaphoid and outer cuneiform bones. This bone is convex on its upper sur- face, and on the lower surface it has a deep groove, in which the tendon of the peroneous longus muscle plays. There are two muscles attached to the os cuboides, viz. the flexor brevis minimi digiti and adductor pollicis pedis. 76 OSSEOUS SYSTEM b- THE metatarsal bones. a. The metatarsus consists of five bones. Fig. 74, a, the first, or that of the great toe, is the largest Fig. 74. Fig. 75. and thickest; the o- ther metatarsal bones are long and slender. Fig. 75, a, the second, is the longest ; the others decrease in length to the fifth, or little toe. Each bone has flat articular sur- faces to unite with the metatarsus, and a rounded articular sur- face for the first bone of the toe. The me- tatarsal bones also have flat articular sur- faces at these poste- rior extremities for connecting them with each other. There are fourteen muscles attached to these bones, viz. the seven interossei and transversalis pedis, common to all; the tibialis ayiticus and peroneus longus are attached to the first metatarsal bone; the adductor pollicis pedis to the second ; the peroneus brevis, adductor, and flexor brevis minimi digiti, to the fifth. tb OF THE LOWER EXTREMITY. 77 BONES of the toes. There are fourteen bones of the toes: two to the great toe, Fig. 74, b, c; three to each of the other toes, Fig. 75, b, c, d; their division and arrangement are similar to that of the fingers. There are nineteen muscles attached to the phalanges of the toes, viz. on the upper surface the extensor proprius pollicis and extensor longus, et brevis digitorum pedis, and seven interossei. On the lower surface, the flexor longus et brevis, and abductor pollicis, the flexor longus et brevis digitorum pedis, and four lumbricales. SESAMOID BONES1. Besides the bones we have described, there are others seldom preserved in the skeleton: such are the sesamoid bones, which are very small, and found at the roots of the first joint of the thumb and of the great toe. These are under or rather in the flexor tendons: they serve as pul- leys for increasing the angle of insertion, therefore add considerably to the force of the muscles, and protect the articulations. These bones give insertion to the flexor brevis pollicis manus, and to the flexor brevis, abductor, et abductor pol- licis pedis. \ Because they resemble the grains of sesamum, or Indian corn. This term occurs in several parts of descriptive anatomy. " Sesamoid bones are sometimes found at the origin of the gastrocnemii muscles, and occasionally they are connected with the ossa pubis." Moneo. 78 OSSEOUS SYSTEM 76. THE TONGUE BONE. Fig. 76. Os hyoides. There is another bone not immediately connected with the skele- ton, situated at the root of the tongue, the os hyoides'h It serves for the at- tachment of the muscles of the tongue, and of deglutition ; a, a, the great cornua; b, the smaller cornua; c, the basis. The os hyoides is not immediately connected with any other bone, but is kept in its situation by numerous mus- cles and ligaments. . There are ten muscles attached to this bone, viz. the hyo-glossus, constrictor pharyngeus medius, sterno-hyoi- deus, omo-hyoideus, stylo-hyoideus, genio-hyoideus, thyro- hyoideus, genio-hyo-glossus, digastricus, and the mylo hyoideus. i So called from its resembling the Greek letter i>. OF THE TEETH. 79 CHAP. V. THE TEETH. The teeth are the most solid parts of the body; in their formation they bear a certain analogy to the horns of ani- mals, and thus differ in many respects from the bones. Some anatomists have described them as an appendage to the skin, since they are, in fact, exterior to it, and are exposed in a great part of their surface to the contact of the air, and to the mechanical and chemical action of bo- dies. The greater part of their surface is inclosed in alveoli or sockets, which tightly embrace them, and form the arti- culation termed gomphosis. That part which is thus con- tained in the socket is named the root; the middle, which is somewhat contracted, is the ne*zlc; and all above, the crown. All the teeth have a form more or less elongated, terminating in a pointed manner, and in this point or end of the root is a small hole. This opening leads to the hollow of the tooth, or dental cavity, an excavation which extends from the point of the root to the crown ; and this cavity represents the form of the tooth, and lodges its ves sels and nerves. The teeth, when all are developed, are thirty-two in number, sixteen in each jaw. STRUCTURE OF THE TEETH. They are formed of two substances : one exterior, called enamel; the other interior, and of the same texture as bones. 80 OSSEOUS SYSTEM ENAMEL OF THE TEETH. The enamel is only found round the crown of the tooth ; it covers the whole surface of the crown, is moulded ex- actly upon it, and thus represents all its inequalities. It is thickest on that surface where trituration takes place, and diminishes in this respect towards the neck. This dis- position is a protection to the surface which is most worn in mastication. The fibres of the enamel are small, pa- rallel to each other, and perpendicular to the surface of the tooth; by this arrangement the enamel is not liable to scale off, and is better calculated to resist attrition. In Fig. 77, may be seen the enamel, marked a, and extend- ing to b. THE OSSEOUS SUBSTANCE OF THE TEETH. This forms the most considerable portion of the tooth, as the whole of the root and the interior of the crown. It is composed of an exceedingly dense and compact tissue, bearing an analogy to ivory ; for it has no cancelli, and its fibres, when seen by the assistance of a microscope, appear concentric, parallel to the surface of the tooth. By chemical analysis, the osseous substance gives nearly the same results as the other bones, with the exception of a small quantity of fluate of lime. Like the medullary organs of bones, the central part of the teeth contains a soft spongy substance, formed by a network of vessels and nerves. The vessels are derived from the internal maxillary artery; the nerves, from the second and third branches of the fifth pair. Fig. 77, is a section of an incisor and molar tooth, showing the cavity " which contain the nerve and vessels mark- ed c, c. OF THE TEETH. 81 CLASSES OF TEETH. The teeth are divided into three classes: incisors, ca- nine teeth, and grinders. INCISORS. The front or cutting teeth are eight in number, four in each jaw. They vary from the others in the form of the crown, which is like a wedge. They are convex in front, concave posteriorly. The layer of enamel which covers the crown is thinner behind than in front. The roots of these teeth are always single, very long, and of a conical form, slightly compressed at the sides, and a little thicker before than behind. Fig. 78, shews a front, and Fig. 79, the 7g 7g profile of an incisor. The lower incisors are smaller than the upper, their roots larger, and laterally more compressed, sometimes deeply furrowed. CANINE TEETH. These are called also cuspidati, from their being spear- pointed. There are two in each jaw, placed next in order at the sides of the incisors. They have each but one root, which is longer than the corresponding portion of any of the other teeth. Fig. 80, the front, Fig. 81, 80. 81. the profile. The canine teeth of the upper have longer roots than those of the lower, and are vulgarly called eye-teeth, and those of the lower jaw stomach-teeth. VOL. I. 12 82 OSSEOUS SYSTEM THE GRINDERS, Or molar teeth, are twenty in number, ten in each jaw, five on each side. The two first pairs of grinders are called bicuspidati. Their crown is surmounted by two conical tubercles; the root is generally simple, but has a well-defined groove on each of its la- teral surfaces. Fig. 82, a front view, and Fig. 83, the profile of a small grinder. The next three, which terminate the row, are called multicuspidati. They are remarkable for their great size, and on the surface of their crown are four pyramidal tu- bercles, separated by very distinct grooves; their root is divided into two, three, four, or five parts or fangs, each of which presents an aperture for the passage of the dental nerve and vessels. Fig. 84, a view of a large grinder. The root of the last grinder (dens sapientia) in the lower jaw is simple, short, and conical; but in the upper jaw it is generally divided into four short roots. OF THE FORMATION OF THE TEETH. The teeth are formed in a manner different from that of any other part of the body, and their development pre- sents many remarkable phenomena. Before they are visible, they are formed in the interior of the maxillary bones. They are developed in small rounded sacs, which sacs are composed of two membranes ; both these membranes are vascular, according to Meckel and Fox, but the external is the more so. The internal membrane is the firmest, but thinner than the external; OF THE TEETH. 83 its connexions with the teeth are more intimate, for strictly speaking, this is the formative organ. The dental vessels branch out on it; and when it is injected, it appears entirely red. The external is of a more spongy, looser, softer, and thicker texture, than the internal; it is conti- nuous with the gums, lines the interior of the alveoli, and forms their periosteum. At the first, these small sacs inclose a reddish fluid sim- ply ; but at about the fourth month of pregnancy, there appears from the base of the internal membrane a small body, which is vascular and soft. This is the germ, or pulp of the tooth. Numerous nerves and vessels, supplied by the internal membrane, ramify in this pulp, which gra- dually assumes the appearance of a tooth, this being the nucleus around which a tooth is moulded. The ossification of the tooth commences about the mid- dle term of pregnancy, and begins on as many points of the pulp as the future tooth will have eminences on its surface ; thus the incisores and cuspidati commence with one point, and the molares with several. The several points increase until they come in contact, then the tooth grows as an entire body. The pulp elongates at its base to form the root. In those teeth which have only one root, a conical shell of bone is formed around the pulp, which continues to increase in length in proportion as the ossification advances; while in those which have several roots, a division of the pulp takes place at this part into a corresponding number of processes. The outer lamina of bone is first completed ; and then lamina after lamina is deposited, one within the other, the pulp still receding, until at length there remains only the permanent cavity of the tooth, lined with its proper mem- brane, and filled with the remaining portion of the pulp, which now serves as the bed upon which the vessels and 84 OSSEOUS SYSTEM nerves ramify previously to their entering the bony sub- stance of the tooth. The secretion of the enamel begins shortly after the de- velopment of the bony matter; this substance is secreted by the internal face of the internal capsule which enve- lopes the crown of the tooth, so that it is moulded exactly to the projections and depressions on that part. The fluid which is poured out from this internal membrane is thickish, and it is soon consolidated into a dark chalky substance, which afterwards becomes white and hardened by more perfect crystallization. This is the enamel; but at an early period this enamel is not very hard, and can be easily separated, and can in its perfect state be readily detached by heat. The glandular apparatus which forms this sub- stance is not demonstrable. OF THE DECIDUOUS TEETH. Infants have teeth which are the deciduous or milk teeth, twenty in number, ten in each jaw, five on each side, viz. two incisors, one cuspidatus, and two molares. These commence to appear ordinarily about the sixth month, and generally in pairs, those of the lower jaws first, and then the similar ones in the upper; and the whole twenty ap- pear at about the thirtieth month. OF THE PERMANENT TEETH. The deciduous teeth drop from the gums, and are fol- lowed by the permanent; and the whole process of den- tition is not completed until about the age of twenty years, the last appearing being the dentes sapientiae. These per- manent teeth are developed, and appear nearly in the same order as the milk teeth. OF THE TEETH. 85 Nature has limited the duration of life in the teeth more than in the other bones. The power of nutrition becomes gradually enfeebled in these organs, and they perish by their nutritious foramina being obliterated. Being no longer retained in their alveoli by any organic connection, they become loose and fall out; their sockets are absorbed. But the tone of the stomach being weakened naturally at this advanced period of life, man is thereby reduced to feed upon soft substances, accommodated to the languid state of the gastric powers and the loss of the teeth. 86 MEDULLARY SYSTEM, CHAP. VI. THE MEDULLARY SYSTEM, OR THE MARROW OF BONES. I shall first describe the deposition of marrow occupying the cellular structure of the short and flat bones, and the extremities of the long bones. The medullary membrane of this structure appears to be a continuation and expan- sion of the vessels that penetrate the foramina, and which, on reaching the internal surface of the spongy part of the bone, ramify ad infinitum, and unite a thousand different ways. Their interweavings give to the interior of the cellular tissue its peculiar florid aspect, which is more evident as we examine it nearer to the period of infancy, because the vascular system of bones is then very conspi- cuous, while it gradually contracts and fades away as age advancesk. This vascular extension can be distinctly seen in the injected bone, forming, as it were, a membrane throughout the innumerable cellulae of the bone ; and the exhalation of the medullary fluid or marrow, which fills the interstices I have just mentioned, seems to proceed from this vascular network. The medullary system of the middle of long bones, whose largest cavity it fills, somewhat differs from the preceding, in having less vascularity; while a thin trans- it The blood vessels of bones are much more numerous than we should expect from their colour, for the earth of the bone conceals them; and hence they are not apparent even after being filled with a red injection, until by immersion in diluted muriatic acid the earth of the bone has been destroyed. When a bone has been thus prepared, and put into oil of tur- pentine, its vascularity is shown to great advantage. OR MARROW OF BONES. 87 parent membrane lines the whole cavity, and is repeatedly folded upon itself, giving rise to numerous extensions, some of which surround the very minute filaments of the cancelli of the sides of the cavity, others pass from the one side of the membrane to the other without adhering to any ossified portion, the whole of which forms spherical cells filled with marrow, and when viewed through a microscope resembles a cluster of pearls. The medullary system of bones, in a healthy state, pos- sesses little sensibility, or only such a degree of organic sensibility as is indispensable to its functions. As a proof of this, the marrow may be irritated in a living animal without any sign of feeling being expressed. The sawing of the skull with the trephine, and the division of the bone in amputations, are not attended with pain. Marrow, according to Berzelius, is a species of fixed oil, possessing peculiar properties, and something like but- ter. It consists of the following ingredients: Pure marrowy or fixed oil Skin and blood vessels . Albumen ~\ Gelatine / Extractive I Peculiar matter 1 Water....... The use of the marrow in bones, I believe to be the same as the use of the fat in or about other parts of the human body, viz. it is a mere deposit of superfluous nutri- tious matter. 0.96 0.01 0.03 1.03 ART. II. CHAP. I. CARTILAGINOUS SYSTEM, OR THE GRISTLE OF BONES, ETC. In order to render the motions of the bones on each other more easy, the ends are incrusted with a substance of a white or pearly colour, hard, yet very elastic. This is a peculiar substance found in various parts of the body, espe- cially on the articular surfaces of bones, the end of the nose, the edges of the eye-lids, the ear, the wind-pipe and air passages, the ends of the ribs, etc. Cartilage forms a considerable share of those parts where flexibility and firmness are to a certain degree combined, in order that the organ may, after being bent, recover its deter- mined form. The cartilaginous tissue is a network of fibres, so closely interwoven that at first sight it appears completely homo- geneous, and formed of a mass of albumen without any particular order or direction ; however, a more attentive examination will discover longitudinal fibres, crossed by others in a transverse direction. The fibrous arrangements of the cartilage of joints are perpendicular to the surface of the joint, and after maceration for six or eight weeks, may be observed to be placed at right angles in respect to the bone to which they are united. The surfaces of cartilage which are in contact are finely polished, that by its smoothness it may facilitate the sliding motion of the two bones on each other. The elasticity reflects a considerable part of the motion, which by a little yielding becomes extended, and thus moderates the effects CARTILAGINOUS SYSTEM. 89 of violent shocks to which the limbs are often liable in active exertions. The elasticity of cartilage is very conspicuous, particu- larly in youth and adult age. If the blade of a scalpel is thrust into cartilage, the two edges of the division will re-act upon it, and repel the instrument; when pressed it becomes flattened, but resumes its primitive shape as soon as the cause of compression is removed. Thus has nature placed cartilages waere, to answer particular purposes, it is requisite that a physical property should be united to the vital powers, as in the larynx; and in the nasal parti- tion, to produce a kind of vibration in the passage of air; at the end of the ribs, to maintain that kind of contortion indispensable to mechanical respiration ; and in the arti- cular extremities, to resist the effects of external violence, for in those situations they serve as a kind of elastic cu- shions, yielding on compression, and regaining their form on that compression being removed. During life this elasticity of cartilage is most apparent, although it remains after death. The cartilages are divided into articular, interarticular, connecting cartilages, and cartilages of particular cavities. Articular cartilages cover the surfaces of bones in the moveable joints. Interarticular cartilages are interposed between the ends of bones to form a moveable socket, which, like the fric- tion wheels of machinery, aid the motion of the joint. Connecting cartilages unite the articular surfaces of bones by an immoveable union, as in the sutures of the skull, the connections of the bones of the pelvis, etc. Cartilages of cavities are such as form the larynx, tra- chea, part of the nose, etc. The number and the thickness of cartilages interposed between each bone, renders the acts of running, jumping, and performing other feats of activity, much more easy. vol. i. 13 90 CARTILAGINOUS SYSTEM. Severe blows on the ribs do not break them, for their car- tilaginous extremities recoil, and yield to the violence; as, however, in age the quantity of cartilage diminishes, and some cartilages entirely disappear, so the bones lose that elastic medium, their extremities are unyielding and ine- lastic, and any degree of violence is frequently attended with fracture. For instance, a child falling twice its height, from the elasticity of its frame would receive little or no injury; the condition of old age is very different: the bones are consolidated, and a fall of the same nature might prove the most disastrous. The blood-vessels, nerves, and absorbent vessels of car- tilage, are so small as to elude observation; but there cannot be a doubt of their existence, of which there is the clearest evidence from the phenomena of its inflammation and absorption in disease; but in its natural state its vita- lity is very obscure, sensibility and contractility being such only as are necessary for its growth and nutrition. When divided, if the edges be brought into contact, after a length of time re-union will take place, as I have observed in wounds of the cartilage of the nose and of the ear. ART. III. CHAP. I. FIBROUS SYSTEM. All the fibrous organs are absolutely of a similar nature, and the same fibres contribute to the composition of all the forms ; yet, in their arrangement, they vary in an astonish- ing degree; and it is the variety in their form, situation, and office, that has caused them to be denominated and designated by the names of tendons, aponeuroses, liga- ments, etc. The fibrous parts of the human system everywhere dis- play a whitish, or shining silvery appearance. The basis is a dense fibre of a peculiar nature, rather elastic, insen- sible, hardly admitting of contractility, sometimes arranged in juxta-position, and assembled together in bundles pa- rallel to each other, as in the tendons and ligaments; at other times they are intersected and spread out in sheets, the fibrous web of which turns in diversified directions, as in the membranes, the capsules, the fibrous sheaths, etc. The strength of the fibrous tissue renders every organ it composes fitted to sustain the utmost efforts its uses require. Thus the ligaments strongly retain the articular surfaces in apposition. The aponeuroses prevent the displacement of the muscles, and give attachment to their fibres. The tendons, incessantly exposed to the contrac- tion of the muscles, are placed between the power they conduct and their attachments, offering a resistance that 92 FIBROUS SYSTEM frequently proves stronger than the bone itself. For by muscular exertions the patella, the olecranon, and the os calcis, have been sometimes fractured. The several forms of the fibrous membranes are— 1st. Those which include the periosteum, the dura mater, the tunica sclerotica, the tunica albuginea, the pro- per membranes of the kidneys, spleen, etc. They are generally intended to cover certain organs, to the texture of which they contribute. 2nd. The fibrous capsules, very different, as will be shown, from the synovial surfaces, are a kind of cylindrical bags that are found around some articulations, especially round those of the humerus and the femur, where they are connected with the scapula and ilium, inclosing both their articular surfaces. 3rd. The fibrous sheaths are intended to confine the tendons in their situation, particularly on their passing over the bones, where they undergo flexion, as in the fin- gers and toes ; for without this contrivance they would be liable to deviate, and thus transmit but imperfectly mus- cular motion. The fibrous sheaths have been divided into two species : those which confine a number of tendons, as at the wrist, instep, etc. others, like those of the fingers, are intended for an isolated tendon, or for the reception of two only. 4th. The aponeuroses are a kind of fibrous canvass, more or less extended, and always connected with loco- motion, and disposed in such a manner that they some- times form coverings for different parts, at other times they provide the muscles with points of insertion. The fibrous organs formed in fasciculi are— 1st. The tendons found at the extremities, or in the centre of muscles; these are either single, in the form of OF THE PERICHONDRIUM. 93 extended strings, or compound, as in the rectus femoris, flexors, etc. 2nd. The ligaments which secure the articulations, round which they are placed; these are formed of regular fasciculi, as the ligaments of the jaw, elbow, knee, etc. or of irregular fasciculi, as those of the ribs, pelvis, etc. CHAP. II. PERICHONDRIUM. This is a membrane perfectly similar to the periosteum; it covers the cartilages in the same manner, and serves the same general purposes to cartilage as the periosteum does to bone. The perichondrium of the larynx, the ribs, etc. is a thin tissue of fibres, intersected in every direction, is highly vascular, and can be injected. But the vessels of this membrane, where it covers the articular surfaces, can- not be demonstrated ; indeed, it adheres so closely as to appear like the cartilage itself, although it can be proved to be a reflection of the synovial membrane of the joint. 94 FIBROUS SYSTEM CHAP. III. THE LIGAMENTS. The ligaments are that apparatus which connects the articular ends of the bones and cartilages, by which they are all united into one admirable structure, the individual parts of which are firmly maintained in such particular relative situations as are best calculated to admit with safety the numerous motions that are required. The bones are united by strong investing membranes, and by flexible and elastic bands, composed of dense fibres intimately interwoven with each other, and passing in dif- ferent directions, the greater number of which pass in direct lines between the parts which the ligaments con- nect. The ligaments then may be described as an assem- blage of strong fibres, firmly joining together the articular surfaces of bones, and giving that security which will pre- vent displacement, and yet such a latitude of motion as will admit of the easy movement of one bone on the other. The ligaments receive their supply of blood from the vessels in their immediate vicinity ; they possess but a very small share of elasticity, and in a sound state are nearly destitute of sensibility. Bichat asserts that no nerves can be discovered in them; but Dr. Monro traced them distinctly into their substance, and we know under diseased excitement they are extremely sensible. CAPSULAR LIGAMENTS. I have mentioned the periosteum as covering the bone : the same periosteum, as it were, is continued over the OF THE LIGAMENTS. 95 joint, and forms a loose bag termed the capsular ligament, which contains the glairy fluid1 with which the joint is lubricated. The capsular ligaments are strengthened by the addition of irregular fasciculi of fibres which cross over the joints in different directions ; not to mention that the further security of the joint is provided for by the muscles and tendons which pass over it. LATERAL LIGAMENTS, These ligaments are strong skeins of fibres, firmly united to the periosteum, and passing from one extremity of bone to another, and are always found in the hinge-like joints. The lateral ligaments moderate, and in some measure limit, the movements of the joint. LIGAMENTS WITHIN THE JOINTS. These ligaments are for giving additional strength, and regulating the movements of certain articulations, as the round ligament of the hip, and the cross ligaments of the knee. These are the principal species of ligaments of the body; there are, however, others that unite the bones which do not move on each other, as the os sacrum and os innomi- natum. There is also an elastic substance, which is an antagonist to the muscles, and by which they are restored to their original situation, or supported in it. These some- times form part of the muscles ; thus the head is supported by a strong elastic ligament appended to the muscles of 1 The synovial membrane which produces this fluid must be distinguished from the cap- sular ligament. The former is allied by structure and function to the serous membranes, the latter to the fibrous. 96 FIBROUS SYSTEM the back. In those animals which have long necks, this is particularly strong, as in the ox and the horse ; for the head acting at the end of a long lever, could not be sup- ported for any length of time, or would be in danger of dislocation, were it not for this elastic tape, which supports the head without the expense of muscular power. Those ligaments usually denominated interosseous ligaments, placed between the radius and ulna, tibia and fibula, etc. are simply aponeurotic membranes, serving for the attach- ment of muscles ; and thus supplying the place of bones, save an unnecessary weight and incumbrance. CHAP. IV. PARTICULAR LIGAMENTS. LIGAMENTS OF THE HEAD. These may be divided into two classes : the first con- nects the lower jaw to the temporal bones ; the second, the head to the neck. LIGAMENTS OF THE LOWER JAW. The condyles of the jaw are fixed to the articular cavi- ties of the temporal bone by a capsular and two lateral ligaments, with the addition of an interarticular cartilage. OF THE LIGAMENTS. 97 82. CAPSULAR LIGAMENT. The capsular ligament consists of dense fibres, which are superiorly attached to c, the margin of the zygomatic eminence, and to the fissure in the glenoid cavity. It is again attached to the edge of b, the interarti- cular cartilage, and in- serted inferiorly at a into the neck of the condyle of the lower jaw. Fig. 82 exhibits a section of the joint. INTERARTICULAR CARTILAGE. This cartilage, b, forms a sort of moveable cover over each condyle of the jaw, separating the capsule into two parts, by its circumference adhering strongly to it. INTERNAL LATERAL LIGAMENT. Fig. 83. This ligament is attached above at a, the edge of the gle- noid cavity; below at b, the margin of the posterior dental fora- men, in the ramus of the jaw. VOL 98 FIBROUS SYSTEM STYLO-MAXILLARY LIGAMENT. This ligament is extended from c, the styloid process of the temporal bone, to e, the angle of the jaw. EXTERNAL LATERAL LIGAMENT. Fig. 84. This ligament passes obliquely across the capsular ligament, from a, the zygoma, to the posterior part of b, the neck of the jaw. a LIGAMENTS CONNECTING THE HEAD AND NECK. Fig. 85. The ligaments con- necting the head to the neck may be ar- ranged as follows:— the capsular, perpen- dicular, and lateral ligaments. TWO CAPSULAR LIGAMENTS. These ligaments connect the condyles of the occipital bone to the articulating cavities of the atlas. OF THE LIGAMENTS. 99 ANTERIOR PERPENDICULAR LIGAMENT, A broad ligament attached superiorly to the anterior edge of the foramen magnum, and inferiorly to the ring of the atlas; its fibres extend some distance down the cer- vical vertebrae. POSTERIOR PERPENDICULAR LIGAMENT. A broad and strong ligament, extending from the pos- terior edge of the occipital foramen to the upper vertebrae of the neck. Its direction and attachments are shown in Fig. 85, from a to a, though a part of it is removed to show other ligaments. TWO LATERAL LIGAMENTS. These ligaments, Fig. 85, b, b, are seen extending from the margin of the occipital foramen to the odontoid pro- cess of the dentata or second vertebrae. CHAP. V. LIGAMENTS OF THE VERTEBRiE. The spinal column is composed of numerous bones, so wonderfully connected to each other, that motion is per- mitted to a requisite extent, without the safety of the spinal marrow, or the strength of the column, being in the least impaired. Several ligaments are required to effect these important purposes: these differ from each other in 100 FIBROUS SYSTEM form and in use: some are common to all the vertebrae, others are confined to two of them, others again are pecu- liar to the cervical vertebrae. LIGAMENTS OF THE SECOND VERTEBRA. TRANSVERSE LIGAMENT. This is a strong fasciculus of ligamentous fibres, Fig. 85, c, extending from one side of the articular process of the atlas to the opposite side ; it is narrow at the extremities, but wide in the centre, where it is almost of a cartilaginous hardness. This ligament secures the odontoid process in its proper place, and prevents the possibility of its pres- sure on the spinal chord. LIGAMENTS COMMON TO ALL THE VERTEBRA. ANTERIOR COMMON LIGAMENT This is a smooth, resplendent, broad ligament, a, a, which extends along the anterior convex surface of all the ver- tebrae. This ligament is composed of parallel fasciculi, which, however, sel- dom extend beyond two or three verte- brae, where one set terminates and ano- ther commences; thus its entire extent receives an access of fibres from almost every vertebra it covers. It is attached only to the anterior part of the spinal column, though occasionally it sends off small oblique processes, which are lost on its sides. A profile of this ligament is seen in Fig. 91, c. Fig. 86. OF THE LIGAMENTS. 101 POSTERIOR COMMON LIGAMENT. 87. This is somewhat similar to the anterior, except that it passes along the inner concave part of the bodies of the vertebrae, and terminates at the sacrum ; a, the intervertebral fibro-cartilage, cut transversely; b, b, b, b, the part from which the arch of the spinal canal is removed; c, c, the posterior vertebral ligament, situated behind the bodies of , the vertebrae, smooth and resplendent, broader on a level with each fibro-car- tilage than with the body of the vertebra. • There are numerous short and strong igamentous fibres crossing each other obliquely, joining the vertebrae together ' upon the outer edges of the vertebral substance, called by F yfe, crucial inter- vertebral ligaments. INTERVERTEBRAL LIGAMENT. Fig. 86, c, c, c, c, c. There is placed between the bodies of the vertebrae a peculiar substance, described by most authors as a texture between cartilage and ligament, partaking of the property of both, hence sometimes very properly called interver- tebral fibro-cartilage. It is composed of white shining fibres, arranged in laminae of different thicknesses, but in very regular order. If this substance is divided by a hori- zontal section, its fibrous structure is very distinctly seen, the lamince running in regular concentric circles, or rather 102 FIBROUS SYSTEM the circle is a little concave posteriorly, corresponding to the form of the articular surface of the bodies of the ver- tebrae. Although the external laminae are of a cartila- ginous firmness, and offering great resistance on pressure, the internal laminae are more soft and delicate, and at a greater distance from each other, in the interstices of which there is a peculiar substance, not so firm as cartilage, nor quite so soft as gelatin. The smaller circles of fibres are gradually softer in their texture as they approach the cen- tre, where nothing is seen except a nucleus of semi-liquid or mucous form. Thus each vertebra resting on a sort of fluid fulcrum, or pivot, the motion, to either side is easy, and quickly performed. The motions of the back bone or bones, therefore, are performed on an almost fluid centre, surrounded by a perfectly elastic medium, which remark- able union of flat surfaces admits of the requisite degree of motion, and prevents injury to the delicate texture of the spinal chord and brain in violent exercise. LIGAMENTA SUBFLAVA. These ligaments are of a pale yellow colour; they are attached superiorly and inferiorly to the opposite margins of the arch of the spinous processes of the vertebrae, completing those deficiencies of the spinal canal which are observed in the skeleton at the posterior part of the spine, and extending as far forwards as the oblique processes, the articulations of which they strengthen. These ligaments possess great elasticity, yet resist too much flexion of the vertebral column. OF THE LIGAMENTS. 103 INTERSPINOUS LIGAMENTS. 88. The interspinous liga- ments, Fig. 88, b, b, b, are attached to the upper and lower margins of each spi- nous process. Like the in- terosseous membranes of the fore arm and leg, they present an extensive surface for the attachment of muscles, and connect one spinous process with another. SUPRASPINOUS LIGAMENTS. The supraspinous ligaments, Fig. 88, a, a, are extended from the point of one spinous process to that of another, in the whole line from the seventh cervical vertebra to the sacrum. LIGAMENTS OF THE OBLIQ.UE PROCESS. The articulations of the oblique articular processes of the vertebrae are secured by a strong capsular ligament, composed of short fibres, which permit but little motion, except between the first and second vertebra, the articular processes of which are very large, and the ligament allows of a considerable rotatory motion. 104 FIBROUS SYSTEM CHAP. VI. LIGAMENTS OF THE THORAX. LIGAMENTS OF THE RIBS WITH THE VERTEBRA. CAPSULAR LIGAMENTS. The capsular ligaments are attached to the heads of the ribs ; and as there are two articular surfaces to the head of each rib, so there are two regular capsular liga- ments, which are opened in the figure, a, a; their fibres are radiated, one portion of its fasciculi being extended to the vertebra above, another to that below. The fibres of the capsule extend along the bone for some way, and mix with their anterior common ligament. The back of the rib is articulated to the transverse process; conse- quently there is a capsular ligament belonging to this joint also. INTERARTICULAR LIGAMENT. The interarticular ligament, Fig. 89, b, is fixed to the central projecting angle on the head of each rib, connect- ing it to the intervertebral substance. This ligament has no existence in the first and two last ribs: as the capsular ligaments are single, each has but one articular surface on its head, and is connected with one vertebra only. OF THE LIGAMENTS. 105 MIDDLE TRANSVERSE LIGAMENT. This ligament, a, consists Fig. 90. of irregular fasciculi of fibres, which occupy the interval between the rib at c, and the anterior surface of the corre- sponding transverse process at b. It cannot be well seen until the rib is forcibly separated from its attachments. INFERIOR TRANSVERSE LIGAMENT. Fig. 91. This ligament, e, e, is composed of two fasciculi, the one extending from the lower edge of the transverse process of the vertebra to the upper edge of the rib above, near its articulation with the body of the vertebra. The other fas- ciculus is smaller, and is attached to the base of the trans- verse process, and is extended to the head of the rib beneath. ANTERIOR OR RADIATED LIGAMENT. This ligament, Fig. 91, d, d, is formed of three flat fibrous fasciculi, which are fixed separately to the two VOL. T. 15 106 FIBROUS SYSTEM vertebrae, and to b, the fibro-cartilage ; these strongly se- cure the rib, by converging and attaching themselves to its head and neck. The eleventh and twelfth ribs, however, in this situation, present only a single order of fibres. LIGAMENTS OF THE CARTILAGES OF THE RIBS WITH THE STERNUM. The cartilages of the seven superior ribs are joined to b, the sternum, by strong ligamentous Fl8-!'2- bands at a, which cover the syno- vial membranes ; although this arti- culation has but a very obscure motion, it has a regular socket and capsule. These cartilages are united \ to the ribs by symphysis, or an immoveable articulation. The upper part of the sternum receives some ligamen- tous fibres from its articulations with the clavicles. The sternum is also covered, both on its anterior and posterior surfaces, by a strong aponeurosis, which is inseparably connected to the periosteum ; its fibres are very conspi- cuous anteriorly, and resemble tendinous bands, taking a longitudinal direction, and uniting those portions of the bone which in young persons it is found to consist of. Some fasciculi extend beyond the margins of the ster- num, and are attached to the cartilages of the ribs. The aponeurosis which covers the internal surface of this bone is more smooth and polished, and its fibres take a longitu- dinal course. The xiphoid or ensiform cartilage is connected to the sternum by the above-mentioned aponeurosis, and has ra- diated ligamentous fasciculi connecting it with that bone, and with the cartilage of the seventh rib. OF THE LIGAMENTS. 107 CHAP. VII. LIGAMENTS OF THE PELVIS. These consist of the ligaments connecting the ossa inno- minata, the sacrum, and coccyx. LONG POSTERIOR LIGAMENT OF THE ILIUM. Fig. 93. This ligament is attached outwardly at a to the posterior superior spine of the ilium, descends obliquely inwards, and is inserted at d into the third and fourth transverse tu- bercles of the sacrum; g, the great sacro-sciatic ligament. SHORT POSTERIOR LIGAMENT. This ligament is attached inwardly in common with the preceding, and extends to the third tubercle of the sacrum at c. 108 FIBROUS SYSTEM POSTERIOR LATERAL LIGAMENT. This is a narrow ligament, extending from the internal surface of the same spinous process of the ilium at a, to the lower margin of the first division of the sacrum, b. GREAT SACRO-SCIATIC LIGAMENT. Fig. 94. This ligament is situated at the lower and posterior part of the pelvis ; it is of a triangular form, attached superiorly at a, a, the posterior and inferior iliac spine, to the fourth and fifth tubercles of the sacrum, to the lower portion of this bone and to the coccyx. The fibres converge, and pass obliquely outwards and downwards to be inferiorly attached at a, the tuber ischii. OF THE LIGAMENTS. 109 SMALLER SACRO-SCIATIC LIGAMENT. This ligament is attached inwardly at b, b, to the margin of e, e, the sacrum and coccyx; its converging fibres are outwardly inserted at b, into the spinous process of the ischium. The figure shows the crossing of the sacro-scia- tic ligaments about their centre, giving great support to the contents of the pelvis; these ligaments also give at- tachment to some fibres of the levator ani and coccygeus muscles. The coccyx is connected to the sacrum by a strong ten- dinous aponeurosis, e, e, which is continued down from the tendons of the lumbar muscles ; beneath this are two strong ligaments, which pass from the last spinous tubercle of the sacrum to the first bone of the coccyx ; and there is also a capsular ligament between the sacrum and coccyx. SUPERIOR ILIO-LUMBAR LIGAMENT. This ligament, Fig. 93, e, runs transversely from the upper edge of the ilium to the transverse processes of the two last lumbar vertebrae. INFERIOR ILIO-LUMBAR LIGAMENT. This ligament, /, is situated immediately below the former, runs the same course, and has nearly the same attachments. 110 FIBROUS SYSTEM ILIO-SACRAL LIGAMENTS. The anterior part of the surface of the sacrum and ilium are mutually connected by cartilage, the posterior by strong ligaments, which pass in every direction from one bone to the other. This synchondrosis in front, and syndesmosis behind, is so very strong, as to prevent any motion be- tween the ilium and sacrum. SYMPHYSIS OF THE OSSA PUBIS. The fibro-cartilaginous connection of these bones con- sists of concentric layers, which unite the two oval sur- faces which the ossa ilii present anteriorly, and they are further secured by strong ligamentous fibres, crossing from one side to the other; an examination of which must lead us to deny the possibility of any separation taking place in parturition. MEMBRANE OF THE THYROID FORAMEN. This is a fine, smooth, tense membrane, attached to the circumference of this opening ; it consists of two laminae, the use of which is to give origin to the external and in- ternal obturator muscles. LIGAMENT OF FALLOPIUS OR POUPART. This has been considered as a tendon at the inferior border of the external oblique muscle; it may, however, be strictly considered as a distinct ligament, extending from the anterior superior spinous process of the ilium to the OF THE LIGAMENTS. Ill ossa pubis. To its upper edge the abdominal muscles are attached, and to its lower the fascia lata of the thigh. It is subtended like a cord across the cavity between the spine of the ilium and the pubis, thus protecting the femo- ral vessels and nerves as they leave the pelvis along with the psoas and iliac muscles. CHAP. VIII. LIGAMENTS OF THE SUPERIOR EXTREMITIES. Under this head I shall describe the ligaments of the clavicle, shoulder, arm, fore-arm, wrist, and hand. LIGAMENTS OF THE CLAVICLE. INTERCLAVICULAR LIGAMENT. Fig. 95. The interclavicular ligament, a, is a fasciculus of strong ligamentous fibres, extending in a transverse direction above the sternum, from one clavicle to the other, con- necting them together, and attaching those bones to the sternum. 112 FIBROUS SYSTEM STERNO-CLAVICULAR LIGAMENT. This ligament, b, forms an imperfect capsule, its fibres extending over the articulation from the triangular or ster- nal end of the clavicle, to the anterior and posterior sur- faces of the sternum ; a few fibres are also attached to the first rib. INTERARTICULAR CARTILAGE. This is an apparatus similar to the articulation of the jaw; it is a moveable carti- lage, a, thick at its circum- ference, and thin in the cen- tre, adapting the extremity of one bone to the other. It is fixed at one edge to b, the clavicle; and the capsular ligament is adherent to the root of the border. In the figure this ligament is cut, and the bones separated, to ex- hibit the cartilage. COSTO-CLAVICULAR LIGAMENT. The chasm between the clavicle and first rib is closed by this ligament, Fig. 95, e. It is of a rhomboid figure, extending from the inferior surface of the clavicle near its sternal end, to the upper and anterior part of the cartilage of the first rib. Some fibres also adhere to the interarti- cular cartilage. OF THE LIGAMENTS. 113 ACROMIOCLAVICULAR LIGAMENT. This ligament, Fig. 97, f, is attached to the superior and outer rough surface of the clavicle, extending a consi- derable length, to connect the corresponding surface of the acromion scapulae. CORACO-CLAVICULAR LIGAMENT. This ligament, d, is very strong, and is formed by a co- noid fasciculus of diverging fibres fixed to the tuberosity on the outer extremity of the inferior surface of the clavicle, and is extended to the internal part of b, the coracoid pro- cess of the scapula. LIGAMENTS OF THE SCAPULA. ACROMIO-CORACOID LIGAMENT. This ligament, e, is attached to the superior convex sur- face of b, the coracoid process; its fibres, which are thick and strong, ascend obliquely outwards, and are inserted into f the inferior surface of the acromion scapulae. CORACOID LIGAMENT. This is merely a ligamentous chord, g, extended over the semilunar notch so as to convert the latter into a fora- men. The supra-scapular vessels and nerves pass under this ligament. VOL. I. 16 114 FIBROUS SYSTEM LIGAMENTS BETWEEN THE SCAPULA AND HUMERUS. CAPSULAR LIGAMENT. Fig. 97. This ligament, h, consists of an oblong sac, surrounding the neck of the scapula, and inclosing the head of the humerus; the capsule is perforated by /, the long tendon of the biceps muscle passing through it, i.e. between the fibrous and synovial membrane, to be attached to the edge of the glenoid cavity of the scapula. ACCESSORY LIGAMENT. The accessory ligament is formed of a strong fasciculus attached to the coracoid process of the scapula, and direct- ing itself forwards and outwards ; it is expanded over the upper and anterior part of the joint, giving the capsule additional strength. The capsular ligament forms but a loose and weak con- nection between the humerus and shoulder, were it not for the several muscles whose tendons adhere to and strengthen it; the infra-spinatus and teres minor by their united ten- OF THE LIGAMENTS. 115 dons cover it externally, the supra-spinatus superiorly, and the subscapularis internally; in addition to these muscles, the deltoid, the coraco-brachialis, and biceps, all co-ope- rate in no small degree to strengthen the connection be- tween these two bones. There is a fibro-cartilaginous rim which increases the depth of the glenoid cavity of the scapula, termed by Clo- quet the glenoid ligament; although I consider it merely a cartilaginous border to the socket of the scapula, not only useful in rendering the socket deeper, but for preventing fractures of the rim in robust exercises, to which, were it bony, it would be very liable. LIGAMENTS BETWEEN THE HUMERUS ANt BONIS OF THE ARM. CAPSULAR LIGAMENT. The capsular ligament, a, envelopes the entire articula- tion of the elbow joint; on the pos- Fig. 98. terior surface of the humerus it is attached to the margin of the great sigmoid notch which receives the ulna, and passing obliquely downwards be- neath the condyles, round to the fore part of the bone, descends to the ulna ; it is inserted into the olecranon process, into the margin of the sig- moid cavity, and into the orbicular ligament which connects the radius to the ulna. Externally this capsule is rough, and strengthened by bands which run in irregular directions; internally it is lined by the smooth synovial membrane. It is very loose anteriorly and posteriorly, to 116 FIBROUS SYSTEM admit of a free flexion and extension; but on either side it is tense, and strengthened by lateral ligaments, which prevent any lateral motion. EXTERNAL LATERAL LIGAMENT. This ligament, Fig. 98, e, is attached to the most promi- nent point of the external condyle, and descending expands itself so as to be inserted into /, the orbicular ligament, and not into the radius: the rotatory motion of the fore arm on the humerus is thus permitted. Fig. 99. INTERNAL LATERAL LIGAMENT. This ligament, b, is longer and broader than the preced- ing, and extends from the internal condyle of the humerus, in a radiated direction, to the inside of the coro- noid process of the ulna ; a few fibres descend a little backwards, and are attached to the margin of the ole- cranon. The lateral ligaments ad- here so firmly to the capsular, that they appear to form part of its tex- ture. The two ligaments called the ante- rior and the posterior, are both thin and irregular fibrous bands, the one placed in front and the other behind the articulation ; the former is fixed in front of the internal condyle of the hu- merus, and to the annular ligament of the radius; the lat- ter to the posterior part of the external and internal con- dyles of the humerus. OF THE LIGAMENTS. 117 LIGAMENTS BETWEEN THE RADIUS AND ULNA. SUPERIOR ARTICULATION. ORBICULAR LIGAMENT. This ligament, Fig. 98, f surrounds the upper extre- mity of the radius, and with the small sigmoid cavity forms a sort of ring, in which the radius turns with ease. The superior margin is attached to the capsular ligament, the inferior to the neck of the radius. Its use is to confine the head of the radius in its proper situation. ANTERIOR AND POSTERIOR ACCESSORY LIGAMENTS. These are ligamentous fibres which run in various direc- tions upon the fore and back parts of the joint, and contri- bute exceedingly to its strength; the anterior extending from the coronoid process to the orbicular ligament; the posterior from the lower border of that ligament to the lateral smooth surface of the olecranon. MIDDLE ARTICULATION. ROUND LIGAMENT. Chorda transversalis cubiti. This is a small round fibrous chord, Fig. 99, c, extend- ing from the outer side of the tuberosity of the ulna to the radius, a little below the tubercle for the insertion of the biceps. It prevents too great a degree of supination of the radius. 118 FIBROUS SYSTEM INTEROSSEOUS LIGAMENT. This ligament occupies the space which exists between the radius and ulna, although it is not quite so long, being deficient at its upper part. It has the appearance of a thin aponeurotic resplendent membrane, extending from the sharp edge of the radius to the opposite edge of the ulna. It constitutes a medium of connection between these bones, and affords an extensive surface for the attachment of muscles. INFERIOR ARTICULATION. INTERARTICULAR CARTILAGE. Cartilago intermedia triangularis. This is a fibro-cartilage, placed transversely between the lower extremity of the radius and ulna; the superior sur- face is continuous with the cartilaginous covering of the end of the radius, and together with this bone completes the cavity for receiving the upper part of the carpus ; each extremity is connected by strong ligaments to the radius and carpus. The apex of this cartilage is firmly attached to the depression which separates the styloid process of the ulna from the articular surface of that bone. CAPSULAR OR SACCIFORM LIGAMENT. This ligament passes from the radius to the ulna, form ing between them a very loose cul-de-sac, which allows the radius to turn upon the ulna. EXTERNAL LATERAL LIGAMENT. This ligament, Fig. 100, extends from the styloid pro- cess of the radius to the scaphoid bone and annular liga- ment of the carpus. OF THE LIGAMENTS. 119 INTERNAL LATERAL LIGAMENT. This ligament, b, extends from the styloid process of the ulna to the cuneiform bone and annular ligament of the carpus. There are other and more delicate fibres, termed the anterior and posterior ligaments, and there is a syno- vial membrane for the whole articulation. LIGAMENTS OF THE CARPUS. LIGAMENTS OF THE FIRST ROW OF THE CARPAL BONES. Fig. 100, a, b, c, d The three upper bones of the carpus are united toge- ther, 1st, by interosseous li- gaments placed in the inter- vals between the scaphoid, semilunar, and cuneiform bones ; 2nd, by dorsal liga- ments extending transversely, the one between the scaphoid and semilunar bones,the other between the latter and the cuneiform bone; 3d, by pal- mar ligaments, c, similar to the preceding. The pisiform bone is articulated to the cu- neiform by a loose capsular or synovial membrane, strength- ened by some irregular bands of fibres. 100. 120 FIBROUS SYSTEM LIGAMENTS OF THE SECOND ROW OF THE CARPAL BONES. These are united : 1st, by dorsal and palmar ligaments, three on either side, which extend inwards and backwards ; and 2nd, by interosseous ligaments; of these there are only two: both are irregular fasciculi, intermingled with adipose tissue. LIGAMENTS OF THE TWO ROWS OF CARPAL BONES. 1st. There are two short lateral ligaments, the one ex- ternal, the other internal. 2nd. Two fibrous fasciculi, one in front, the other behind, termed the anterior and posterior ligaments; these last-mentioned ligaments form a fibrous membrane, enveloping the whole carpus. 3rd. There is also a synovial membrane which lines the surface, by means of which the two rows of the carpal bones are in contact. Lastly, we find at g, two ligaments of the . pisiform bone, connecting it to the cuneiform bone and the metacarpal bone of the little finger. THE ANNULAR LIGAMENT OF THE CARPUS. The annular ligament is situated on a plane much ante- rior to that of the other ligaments of the carpus ; it is composed of strong and tense fibres, which are attached principally to the cuneiform bone internally, and the tra- pezium externally ; near the latter, some of the fibres are also fixed into the scaphoid bone, and assist in completing the annular passage or channel in which the flexor tendons of the fingers pass, covering and confining them in their course. OF THE LIGAMENTS. 121 LIGAMENTS OF THE HAND. The metacarpal bones are very securely joined to the carpus, not only by their wedge-like surfaces, but also by strong ligaments. CAPSULAR LIGAMENTS. These ligaments are seen distinctly to surround the upper extremity of each metacarpal bone, and are inserted into the opposite bones of the carpus; they are secured by accessory bands, which pass in various directions. SUPERIOR TRANSVERSE LIGAMENTS. These ligaments, d, d, extend across the upper extre- mities of the four metacarpal bones, and are attached to each of themm. INFERIOR TRANSVERSE LIGAMENTS. These ligaments, e, e, present exactly the same arrange- ment, connecting the inferior extremity of the four meta- carpal bones with each other, not indeed so closely as at the upper end, for there is greater freedom of motion at the lower than at the upper part. The metacarpal bones are also united to each other by a strong transverse apo- "i The capsular ligament is the only ligament which connects the trapezium with the metacarpal bone of the thumb. This joint, however, derives much strength from a number of small muscles around it, as well as by accessory bands. VOL. I. 17 122 FIBROUS SYSTEM neurosis, which is connected with the sheath of the flexor tendons, and covers the tendons of the lumbricales and interossei muscles. LIGAMENTS OF THE FINGERS. The first phalanges or rows of the finger bones are at- tached to the metacarpal bones by loose but strong cap- sular ligaments, which are strengthened anteriorly by a semicircular ligament embracing the anterior part of each articulation, and posteriorly by the extensor tendons, which expand very much while passing over these articulations ; also at the sides by lateral ligaments, f f which are at- tached to slight depressions on the lower end of the meta- carpal bones, and into the condyles of the first phalanx. Similar ligaments to these exist at the articulations of the finger bones with each other, viz. each joint has an ante- rior ligament, two lateral ligaments, and a capsular ligament or synovial membrane. The flexor tendons also are confined in their course along the fingers by circular and vaginal ligaments. The former adhere on each side of the tendon to the proper ligaments of the joint, the latter inclose the flexor tendons of each finger in a strong sheath : each sheath is composed of circular fibres, and strengthened by oblique and cunei- form bands, and are attached on each side to the ridge which separates the anterior concave from the posterior or convex surface of each phalanx ; by this means the tendon is confined in the mesial line of the finger. All these sheaths are lined by a smooth synovial membrane. OF THE LIGAMENTS. 123 CHAP. IX. LIGAMENTS OF THE LOWER EXTREMITY. ILIO-FEMORAL LIGAMENTS. The hip joint has great freedom of motion, and requires powerful ligaments ; it is therefore furnished with a syno- vial membrane, a capsular ligament, an inte-rarticular liga- ment, and a cotyloid ligament. COTYLOID LIGAMENT. This is a fibro-cartilaginous substance, attached to the whole circumference of the acetabulum, except at its in- ternal and inferior part, where the bony part also of the margin is deficient; it projects a considerable distance be- yond the bone, so as to deepen the cavity very much. There is another strong band of fibres situated at the lower and internal part of the acetabulum, where the last- described ligament is deficient; it is attached to the pubis, where this bone forms the sinus over the obturator liga- ment, and into the ischium or inferior margin of the notch of the acetabulum : this ligament is superficial to the for- mer, and between both an oblique fissure is left for the passage of vessels to and from the cavity of the joint. 124 FIBROUS SYSTEM CAPSULAR LIGAMENT. The capsular ligament, a, embraces the whole articula- tion of the hip. Excepting the capsular ligament of the knee, it surpasses all similar ligaments in strength, extent, and capacity: it is attached at a considerable distance from the margin of the cavity, particularly in front, where it extends as far as d, the in- ferior spine of the ilium; in- feriorly it is inserted into the femur, incloses the neck of that bone, and descends as far as c, the line which lies between the two trochanters. The synovial membrane does not descend so low as the external capsule, but is reflected on all sides towards the head of the bone; in this course it is bound by folds, and immediately behind the head of the femur it is confined by circular bands. There is a fasciculus of fibres, a, taking an oblique course over the capsule towards the lesser tro- chanter, sometimes called the accessory ligament: it adds strength to this part of the capsule. OF THE LIGAMENTS 125 INTERARTICULAR LIGAMENT. Ligamentum teres. The interarticular liga- ment is a strong triangular fasciculus of fibres, perfectly concealed within the cavity of the acetabulum; in the figure there is a section of the head and neck of the femur, b, and os innomina- tum, e, e, to show the at- tachments of (c) this liga- ment to the bottom of the acetabulum and to the head of the femur. Fig. 102. LIGAMENTS OF THE KNEE JOINT. CAPSULAR LIGAMENT. This ligament or mem- brane is of great extent, since the knee joint is the largest of the whole body ; it is attached at b, h, d, to the whole circumference of the condyles of the femur; anteriorly to e, the patella; inferiorly to the tibia, and to the semilunar cartilages. Above the hollow for the reception of the patella it lines f, the tendon of the extensor muscles: it ad- 126 FIBROUS SYSTEM heres also to the articular surface of the patella in such a manner that this bone seems to form part of the capsule of the joint; lastly, it is reflected over the articular sur- face of i, the tibia, and ligaments within the joints. It is very loose on either side, but tense posteriorly, where it is closely connected with the flexor tendons and posterior crucial ligaments. These connections, as well as the la- teral ligaments, serve to confine this membrane in its situ- ation, and to preserve it in the motions of the joint, from being compressed between the bones. This capsule of the knee, which in itself is very fine and weak, receives considerable strength from additional fibres, termed accessory ligaments. These appear like duplicatures of the capsule at the sides of the patella; they are also called ligamentum alare, majus et minus. There is a fold of the capsular membrane of the same character as those just described, but inclosing a little fat, for which reason some anatomists have given it the name of adipose or mucous ligament; it is situated very near the external condyle, and in front of the anterior crucial ligament; it retains the synovial substance in its proper place in the actions of the joint. Another accessory fasciculus of fibres covers the capsular membrane posteriorly, called the pos- terior ligament of Winslow. OF THE LIGAMENTS. 127 LATERAL LIGAMENTS. The lateral ligaments, as the name implies, are situated at the sides of the joint, and adhere to the capsular liga- ment. EXTERNAL LATERAL LIGAMENT. The external lateral ligament, Fig. 103, a, is a thick round chord, attached to a tubercle on the upper part of b, the external condyle of the femur ; it is adherent to the semilunar cartilage on that side, and is inserted into c, the fibula, a little below its head. INTERNAL LATERAL LIGAMENT. The internal lateral liga- ment, a, is attached superi- orly to the internal condyle, inferiorly to the tibia, the fibres passing obliquely for- wards till they have reached the head of the bone, b, c, d, the ligament of the patella. Fig. 104. 128 FIBROUS SYSTEM CRUCIAL LIGAMENTS. Fig. 105. The crucial ligaments, e, d, are exposed in this figure by throwing down the pa- tella, and removing the adi- pose substance; they are very strong fibrous chords, crossing each other: hence their name. ANTERIOR CRUCIAL LIGAMENT. The anterior crucial ligament, d, is extended from the depression between the two condyles of the femur to the spine in the middle of the articular surface of the head of the tibia. POSTERIOR CRUCIAL LIGAMENT. The posterior crucial ligament, e, is also extended from the depression above named, to a groove behind the spine on the tibia. In Fig. 106, a, the crucial ligaments are separated from the femur, to show their direction and in- sertion into the head of the tibia. The ligament of the patella, Fig. 103,/, g, is merely a continuation of the tendon of the extensor muscles of the leg, in the substance of which, e, the patella seems to be formed, in a similar manner to the sesamoid bones. In OF THE LIGAMENTS. 129 Fig. 105, the patella is represented turned down over the head of the tibia; h, a synovial bursa opened : this is a remarkable bag, extremely loose, and plentifully supplied with synovia. INTERARTICULAR OR SEMILUNAR CARTILAGES. Fig. 105, b, f, Fig. 106, b, c. These are two fibro-cartilages, placed between the con- dyles of the femur and the superior extremity of the tibia; 106. they are of a crescent shape, flexible and elastic; each of these cartilages is broad in the middle, and narrower at their extremities ; the outer convex edge is thick, the inner concave edge thin, thus rendering the cavities for the condyles of the femur deeper, and adapting the tibia more accurately to that bone. The extremities of these carti- lages are fixed by ligaments to the spine in the centre of the articular surface of the tibia; the anterior extremities are joined to each other by a transverse ligament; the outer edges adhere to the capsular and the other ligaments, so as to allow a little play or slight motion upon the tibia, which, by favouring the general motion of the joint, has been compared to the friction wheels of machinery. LIGAMENTS BETWEEN THE TIBIA AND FIBULA. The tibia and fibula are united at their extremities by capsular and other ligaments, and in the middle by an intervening fibrous membrane. VOL. I. 18 130 FIBROUS SYSTEM CAPSULAR LIGAMENT. The capsular ligament of the upper end of the fibula is continuous with the periosteum ; some irregular fibres have been called anterior and posterior ligaments. This arti- culation is moreover secured by the external lateral liga- ment of the knee, and by the tendon of the biceps flexor cruris, part of which passes from the fibula to the tibia. INTEROSSEOUS LIGAMENT. The interosseous ligament of the leg resembles that which is between the radius and ulna ; it is a thin aponeu- rotic membrane, composed of oblique fibres extended from the outer edge of the tibia to the -inner edge of the fibula. This membrane presents several apertures for blood vessels, THE LIGAMENTS OF THE LOWER END OF THE TIBIA AND FIBULA. These ligaments are anterior and posterior, which may be divided into superior and inferior, according to their situations. The superior ligaments are attached to the fibula and tibia, where these two bones are in contact: the anterior having a triangular form, the fibres being the shortest. The inferior ligaments have the same direction as the superior ; they are not so broad, but are thicker and longer; ihey both extend from the extreme point of the tibia to the lowest part of the external malleolus. These four ligaments connect the tibia and fibula so closely to one another, that they appear as one firm piece, whose base is supported by two projections called malleoli, between which the astragalus and os calcis, and of course the whole foot, are firmly secured- OF THE LIGAMENTS. 131 LIGAMENTS OF THE ANKLE JOINT. Strong ligaments pass from the malleoli to the bones of the tarsus; there is also a capsular membrane for the whole articulation. LIGAMENTS BETWEEN THE FIBULA AND TARSUS. The ligaments between the fibula and tarsus are three in number; the anterior passing from the point of the ex- ternal malleolus forwards to the upper part of the astra- galus. The middle is a strong fasciculus of fibres, which descends perpendicularly from the lowest point of the fibula to the side of the os calcis. The posterior is con- cealed by the tendo Achillis: it passes from the external malleolus horizontally inwards, to the back part of the astragalus. LIGAMENTS BETWEEN THE TIBIA AND TARSUS. DELTOID OR TIBIO-TAK.SAL LIGAMENT. This ligament, b, is an as- semblage of fibres extending from the internal malleolus to the astragalus ; inferiorly, its fibres diverge, and are attached to the os calcis; and by c, to the os navicu- lare. 132 FIBROUS SYSTEM CAPSULAR LIGAMENT. The capsular ligament, a, a, is situated within the for- mer ligaments ; it covers the opposed surface of the bones which enter into the articulation, and is very loose: the synovial membrane which lines it contains a great quantity of synovia. LIGAMENTS OF THE TARSUS. The seven bones of the tarsus have a very limited mo- tion between one another, or only such a degree of motion as gives pliancy and elasticity in walking, running, etc. They are united in a manner peculiarly strong, and well adapted to support the weight of the trunk in standing, or in the different motions of the body. See Fig. 107. OF THE LIGAMENTS. 133 LIGAMENTS BETWEEN THE OS CALCIS AND ASTRAGALUS. Fig. 108. There is, 1st, a capsular membrane, b, c, connected to the edges of the articular surfaces of the two bones ; it is closely covered by the lateral ligaments of the ankle, and by the sheaths of the tendons; 2nd, an interosse- ous ligament, formed of a thick fasciculus of fibres, at- tached by one part to the groove which separates the two surfaces of the astraga- lus, and by the other to that which is between the sur- faces of the os calcis; 3rd, by a posteriorligament, com- posed of parallel fibres, a, inserted into the posterior part of the astragalus and into the adjacent part of the os calcis. LIGAMENTS BETWEEN THE ASTRAGALUS AND OS NAVICULARE. This articulation has considerable motion; for the con- vex head of the astragalus is received into the cavity of the navicular bone, in which it is secured by a capsular and accessory ligaments. 134 FIBROUS SYSTEM LIGAMENTS BETWEEN THE OS CALCIS AND NAVICULARE. We find two ligaments passing from one of these bones to the other; they are also connected by a fibro-cartila- ginous trochlea, or inferior ligament, supporting the side of the head of the astragalus, and affording a passage for the tendon of the tibialis posticus muscle ; below this liga- ment there are two external ligaments, which proceed from the anterior internal part of the os calcis to the ex- ternal inferior part of the os naviculare. . LIGAMENTS BETWEEN THE OS CALCIS AND OS CUBOIDES. There is, 1st, a superior ligament, extending from the anterior part of the os calcis to the superior part of the os cuboides; 2d, an inferior ligament, composed of a super- ficial and deep-seated fasciculus of fibres, passing from one bone to the other, and partly to the extremity of the third and fourth metatarsal bones; 3rd, a capsular or synovial membrane, covering the articular surfaces, and the two preceding ligaments. LIGAMENTS BETWEEN THE NAVICULAR AND CUBOID BONES. These bones are connected by a dorsal ligament, I, com- posed of transverse fibres, extending from the navicular to the cuboid bone ; and by a plantar ligament, extending obliquely from the inferior part of the one bone to the neighbouring part of the other. OF THE LIGAMENTS. 135 LIGAMENTS BETWEEN THE NAVICULAR AND CUNEIFORM BONES. The three surfaces of the naviculare are articulated with those of the three cuneiform bones,—1st, by three dorsal ligaments, g, i, k; 2nd, by three plantar ligaments, simi- lar to the preceding, extending from the inferior part of the naviculare to the inferior surfaces of the three cuneiform bones ; 3d, by a synovial membrane, folded on the articu- lar surfaces, and on the plantar and dorsal ligaments. LIGAMENTS BETWEEN THE CUNEIFORM BONES. The cuneiform bones are maintained in apposition by synovial membranes; and by three superior ligaments, e, f, k, extending transversely over thin superior surfaces; and by inferior ligaments, similar to the preceding, but less distinct. LIGAMENTS BETWEEN THE CUBOID AND EXTERNAL CUNEIFORM BONES. The cuboid and external cuneiform bones are united together by strong ligamentous fasciculi, h, which pass from the edge of one bone to that of the other. The su- perior are termed dorsal, the inferior plantar ligaments. LIGAMENTS OF THE TARSUS WITH THE METATARSUS. The tarsal and metatarsal bones are articulated together in a similar manner to the carpus and metacarpus ; i.e. there are, 1st, capsular membranes; 2nd, dorsal, m; 3rd, transverse ligaments, I, each of the metatarsal bones re- ceiving one from the tarsal bone with which it is connected; 136 FIBROUS SYSTEM 4th, plantar ligaments: these are equal in number to the preceding, and disposed nearly in the same manner. LIGAMENTS OF THE METATARSAL BONES WITH EACH OTHER. All the bones of the metatarsus, except the first, are articulated together at their posterior extremities by small cartilaginous surfaces, covered by prolongations of the cap- sular membranes of the preceding articulations, and main- tained, 1st, by dorsal and plantar ligaments: these extend transversely in each region from the second to the third, and from the third to the fourth, and from the fourth to the fifth metatarsal bones ; 2nd, by interosseous fibres, found between the inarticulated points of the posterior ex- tremities of these bones; and 3d, by transverse metatarsal ligaments, o, situated at the anterior extremities of the metatarsal bones, and are in all respects similar to those I have described as belonging to the heads of the four last metacarpal bones. LIGAMENTS OF THE METATARSUS WITH THE PHALANGES OF THE TOES. The posterior extremities of the first phalanges are con- nected to the metatarsal bones at n by capsular and lateral ligaments. LIGAMENTS OF THE PHALANGES OF THE TOES. These ligaments are similar to those of the fingers. The tendons of the foot also are provided with nearly the same sheaths and ligaments as those in the hand, for the purpose of confining them in their situation, and di- recting them in their proper course. The tendons which pass in front and at each side of the ankle joint, are firmly OF THE LIGAMENTS. 13", secured by ligaments and tendinous sheaths, which are attached to the adjacent bones; anteriorly, the extensor tendons are bound down by a strong annular ligament, whose fibres take a circular direction. The plantar aponeurosis is composed of strong liga- mentous fibres, extending from the os calcis as far as the first phalanges of the toes, where it is lost in the tendinous sheaths. Each of the flexor tendons is confined by a strong ligamentous sheath, which is continued along the phalanges in the same manner as in the hand ; these sheaths are strengthened by circular bands at different situations. On the sides of each articulation of the pha- langes with the metatarsus, a fascia is sent off from the ex- tensor tendon : it is composed of glistening fibres, which run towards the sole of the foot, and unite with the plantar aponeurosis ; these fasciae are of important service in re- taining the extensor tendons in their situation. VOL. I. 19 ART. IV. CHAP. I. MUSCULAR SYSTEM. , The organs which we distinguish by the term muscles, are composed of that substance which is commonly known by the name of flesh ; those, therefore, who have not seen the muscles of the human body, may form a very good idea of them by an examination of the flesh of quadrupeds. The muscles are instruments or active agents in produ- cing the various movements of our body; by their means we are endued with the power of moving from place to place, and of performing every manual exercise or bodily exertion. Not only are they the prime moving powers in loco-motion, but speech, singing, and the acts of chewing, swallowing, etc. are performed by muscles; indeed, by means of these organs the blood is circulated, the stomach and intestines urge on their contents, and the different con- duits of the glands propel tbeir fluids. The most characteristic property of muscles is contrac- tility : in whatever position our limbs may repose, it must be muscular contraction to produce their action. Mus- cular contractility also is displayed in the amputation of a limb; for immediately the muscles are divided, the two MUSCULAR SYSTEM. 139 ends contract in opposite directions, leaving between them a space proportionate to their retraction, and the retraction therefore is more or less, according to the length of the muscular fibres. This contractility of muscles constitutes muscular action, and consists in drawing the more moveable towards the most fixed point to which it is connected. Every moveable point in the animal frame is constantly situated between two muscular powers opposed to each other : between those of flexion and extension, of elevation and depres- sion, of adduction and abduction, etc.; this opposition is a condition essential to motion : for in whatever direction the limb is to be moved, the moveable point must neces- sarily be in the opposed direction ; the act of flexion re- quires it should be first extended, and vice versa. But when flexors and extensors are both in a state of action, they counterbalance each other ; there is a rigid "state of the muscles, and the limb is fixed. The effect of every muscle that contracts, is not only to act upon the bone into which it is implanted, but also on the opposite muscle, and this constitutes the phenomena of antagonist muscles ; the muscles are so situated that the one class cannot be extended without the other contracting, and reciprocally. I shall be pardoned if I give the familiar but clear expla- nation of Paley in reference to antagonist muscles:— " Every muscle is provided with an adversary. They act like two sawyers in a pit, by an opposite pull: the nature of the muscular fibre being what it is, the purposes of the animal could be answered by no other. And not only the capacity for motion, but the aspect and symmetry of the body, is preserved by the muscles being thus mar- shalled according to this order ; e. g. the mouth is holden in the middle of the face, and its angles kept in a state of exact correspondency, by several muscles drawing against and balancing each other. In a hemiplegia, when the 140 MUSCULAR SYSTEM. muscles on one side of the face are weakened, the mus- cles on the other side draw the mouth awry." The muscles, on contracting, become evidently harder; they increase in thickness and decrease in length, but their volume remains nearly the same; what is lost in length is compensated in thickness. Prevost and Dumas describe their fibres, in a state of repose, as straight lines; but, when acting, all at once bending themselves in a waved direction, and presenting in an instant a great num- ber of angular and regularly opposed undulations, thus, ^^^^=S; if the cause which led to the contraction ceases, the right lines of the fibres are restored with the same ra- pidity as the waved lines were produced. This contractility, on which depends all the phenomena of animal motion, and which also promotes many of the exterior and interior functions, is exclusively seated in the muscular system. It possesses the faculty of moving under the influence of the brain, whether that influence be de- termined by the will or by other causes. If the brain of a man is compressed, the faculty of contracting the mus- cle ceases. The intensity of muscular contraction, that is, the degree of power with which the extremities of the fibres approximate, is in proportion to the excitement of the brain; it is generally regulated by the will, according to certain limits, which are different in different indivi- duals. When the organization of the muscles is strongly fibrous, and they are of a deep red colour, such muscles, with an equal power of the will, produce much more powerful efforts than muscles whose fibres are fine, pale, and smooth. The cerebral influence and the structure of the muscular tissue, therefore, are the two elements on which depend intensity of muscular contraction. Irritability of muscles, called by Haller the vis insita, is the latent power inherent in the muscular fibres, pro- ducing that tremulous motion which is often felt in various MUSCULAR SYSTEM. 141 parts of the body, without any evident cause, and inde- pendent of the will. It is to be distinguished from mus- cular contractility by being more permanent, and by oc- curring on the application of chemical or mechanical stimuli. A muscle may be separated from the limb, or the heart removed from the body, and for some time afterwards, on pricking it with a needle or passing the electric shock through it, there will be seen convulsive twitchings of its fibres. The irritability of a muscle is present'after death ; and, though doubtless a phenomenon worthy of study, is not to be confounded • with the mus- cular contraction 1 have just described. FORM OF THE MUSCLES. The muscles, like the bones, with reference to their forms, may be divided into long, wide, and short muscles. THE LONG MUSCLES. These muscles are generally placed on the limbs, to the conformation of which they very much contribute. Sepa- rated from the skin by a strong membrane called aponeu- rosis, and from the bone by periosteum, they are contained in a fibrous envelope, which strictly maintains them in their respective situations, and in which they are disposed in layers more or less numerous. In proportion, however, as they are deeper seated they also become shorter ; they. are separated by cellular layers, loose in parts in which extensive motions are performed, and tight wherever the motion is more confined. The long muscles are in some instances a single bundle of fibres, in others they result from an assemblage of many ; scarcely any of the fibres run the whole length of the fleshy mass ; in most of the muscles they are disposed in an oblique direction, between 142 MUSCULAR SYSTEM. two aponeuroses, or between a tendon and an aponeurosis. Some muscles have tendinous intersections, which are placed at different distances in the course of the fibres. THE WTDE MUSCLES. These muscles are generally situated on the parietes of the cavities, especially on those of the chest and abdomen, whose parietes are chiefly formed by them ; they protect the internal organs, aid their functions, and move the body or limbs according as the one or the other is the fixed point. They have always short tendons. The wide muscles are not very thick ; the greatest part of them representing muscular membranes, sometimes disposed in layers, as on the abdomen, at other times applied over the long muscles, as on the back. When the wide muscles are attached to, or are inserted into one of the great cavities, they preserve in all the parts nearly the same width ; but if from a cavity a muscle extends to a long bone, the fibres concentrate by degrees, grow narrower and thicker, and the muscle terminates in a tendon, and thus contracts into a narrow compass the fibres which were largely disseminated. The pectoral and great dorsal muscles are instances of this form and disposition. THE SHORT MUSCLES. These muscles are commonly met with in parts where considerable power on the one hand, and a limited extent of motion on the other, is required, as in the movements of the jaw, the hip, the thumb, and the foot; and most of them have a square or triangular shape. Numerous mus- cles attached to the spine, as the interspinales, recti, etc. display the form I am here describing. They are the most powerful of all the muscles, and are placed where MUSCULAR SYSTEM. 143 great force is required, as at the articulation of the jaw, in the vertebral column, &zc. Though the division of the muscles into long, wide, and short, is similar to that of the bones, and is generally applicable, yet it is liable to a mul- tiplicity of modifications : since nature varies according to the functions which the organs are intended to perform. There are further distinctive characters of muscles, viz. they are simple when the fibres have a parallel direction, as the sartorius or the quadratus lumborum; if they pro- ceed from an extended surface, and converge to a small tendon, they are termed radiated, as the temporal muscle. When the tendon occupies the middle of the muscle, and the fibres are placed obliquely to the tendon like a feather, they are named penniform, as the rectus femoris ; where the muscular fibres are placed on one side of the tendon, it is called half-penniform, as the peroneus longus. In the compound muscles there is a single mass of muscular fibres and several tendons, like the flexors of the fingers, or there are several muscular and tendinous portions, as in the sacro-lumbalis, etc. Sometimes the bundles of fibres and tendons are variously and often intricately woven, as in the lingual muscles. VOLUNTARY, INVOLUNTARY, AND MIXED MUSCLES. The division of muscles into voluntary and involuntary is sufficiently accurate to convey a distinct idea of the two classes of exciting causes. In ordinary circumstances those under the influence of the will must be voluntary muscles, such as the muscles of loco-motion. But there are other muscles over which the will has no dominion : the vital organs, the heart, stomach, and intestines, afford examples of this description, and are brought forward by writers on natural theology as marks of the Divine wisdom ; for were the action of these organs within the control of the will, 144 MUSCULAR SYSTEM. and the vital functions left to man's government, I need not say they would be subject to a thousand interruptions ; these organs, therefore, are furnished with involuntary muscles. There is another class of muscles which are termed mixed, as the diaphragm and other muscles of res- piration, the orbicularis oculi, etc. ; of the action of these muscles we are not sensible, unless the attention of the mind be directed to them ; yet we have the power of in- creasing or suspending their action for a certain length of time. TEXTURE OF MUSCLES. The muscular or fleshy fibres are soft, red, downy, li- near, and possess a small degree of elasticity; they retain little tenacity in the dead body, and are easily torn asun- der, but during life they resist very great force without breaking. A muscle is composed of a number of muscular fasciculi, which are formed of fibres still smaller ; these result from fibres of less volume; at last, by progressive division, we arrive at a fibre no longer practically divisible, but which, were our means of division more perfect, pos- sibly might be reduced to such a degree of tenuity as to elude even the microscope. However, the last of these filaments which can be perceived is the muscular fibre. Numberless researches have been made to determine with certainty the volume of this fibre; I need not mention the result of these researches: the correctness cannot be re- lied on, and the investigation could add nothing to our notions respecting muscular motion. Every muscular fibre runs its extent without ramifying: it is merely in juxta-position with the adjoining ones. The intimate nature of this fibre, upon which so much has been written, is still unknown to us. Prohaska11 found the n Operum minorum pars i, p. 198. MUSCULAR SYSTEM. 145 muscular fibre -^-0 part of an inch in diameter, while Mr. Bauer0 estimates it at only ^. The latter describes the fibres as moniliform, that is, consisting of globules lineally and closely arranged, like the beads of a necklace. Sir E. Home is inclined to consider these globules to be the remains of the globules of the blood from which they have originated, an opinion which the facts of the case by no means warrant; and all that has been affirmed respect- ing the continuation of the muscular fibre with the nervous or vascular organs, is supported by no positive proofs, and is unworthy of claiming a moment's attention. " To ar- rive at correct conclusions, we must study nature where she comes within the cognizance of our senses?." CELLULAR TISSUE OF MUSCLES. The fibres of muscles are united by this substance; it is one of the most important elements of the animal system, consisting of very minute, soft, white filaments, crossing each other in a multitude of different directions, and leav- ing between them certain interstices, which serve for the reception of fat. The muscles are abundantly supplied with this cellular web: it forms a very considerable layer round every muscle; it is most generally loose, or filled with fat; sometimes it is tighter, and actually spread in the form of a membrane, and then the dissection becomes difficult for the young student. Besides affording this ge- neral covering to the muscles, it extends into the substance of these organs themselves, and largely contributes to their structure ; each fasciculus is provided with a continu- ation of sheaths of cellular tissue, and not only surrounds and binds the muscles together, but also unites each of o Phil. Trans. 1818, p. 175. p Bichat. vol. i. 20 146 MUSCULAR SYSTEM. their fibres with those adjoining. These coverings accom- modate the motions of the fibres, which they separate from each other, either by the fat which they contain, or by the serum of the cellulae. The quantity of intermuscular cellular tissue varies very considerably ; sometimes it is so abundant among the muscles as to divide them into separate portions, and con- sequently has confused anatomists in the division of these organs^. BLOOD-VESSELS OF MUSCLES. With the exception of certain viscera, as the lungs, liver, spleen, etc. few organs, in proportion to their size, receive more blood than the muscles; the blood being essentially necessary to keep up excitement, and by this fluid the human muscles are coloured. The arteries are exceedingly apparent: they penetrate their substance from all points of its surface. The principal branches creep at first between the largest fasciculi of fibres; then they di- vide and subdivide into an almost infinite number of rami- fications, which, reduced to capillary tubes, supply the secondary skeins, twine among the most minute fibres, and deposit the nutritive substance of the muscle. The veins of muscles constantly attend the arteries, but surpass them, as they do in all other parts of the body, in number and magnitude. The absorbent vessels may be traced, but not without difficulty. They are most readily injected in the muscles of the face, the tongue, and the diaphragm. q In consequence of these cellular intersections, some authors have divided the deltoid muscle into three distinct muscles. As another instance, I may mention also the pectoralis major, which is thus divided into a clavicular and sternal portion. MUSCULAR SYSTEM. 147 NERVES OF MUSCLES. The muscles are liberally endued with nerves; indeed, excepting the skin and organs of sense, no part of the body is so abundantly supplied with them. Each branch, on reaching the fleshy fibres, first divides, then subdivides in the interstices, until they entirely disappear. Dr, Monro thought that each individual fibre had its corres- ponding nervous filament: and the observation of Bichat may induce one to believe it, namely, that on the principal nervous branch being irritated, every fibre of the muscle comes into play. TENDONS OF MUSCLES. The tendons are a part of the muscle ; they are a kind of fibrous cord, conducting the motions of the muscle to the bone, particularly where there is not room for the in- sertion of the muscular fibres which are necessary for the motion of the joints; they frequently concentrate the whole power of a very large muscle on a small bony surface : indeed, without such a medium of attachment, the articu- lations would be encumbered in their actions. The ten- dons are composed of small white fibres, closely united to each other, having a beautiful shining silvery appearance ; they differ from the ligaments chiefly in this particular, that one of their extremities is attached to the muscle. Tendons possess very little elasticity or sensibility ; they have few blood-vessels, in fact none are observed in their ordinary state ; nor have nerves or lymphatics been traced into them. Some muscles form a complete circle, and have no ten- dinous structure, and are termed sphincters. 148 MUSCULAR SYSTEM. Usually the tendons are at the extremities of muscles, but sometimes are found in the middle, as the digastric muscles, the diaphragm, omo-hyoideus, &c. APONEUROSES. Aponeuroses are precisely similar to tendons ; frequently they seem to result from the expansion of a tendon. They may be divided into two classes : 1st, Aponeuroses of in- sertions, those fibrous expansions which receive fleshy fibres, so as to afford the greatest advantage in multiplying prodigiously the points of insertion, without increasing the extent of bony surface, as the tensor vaginae femoris; others collect the muscular power into a line of attachment, as in the oblique and transverse muscles of the abdomen. - 2nd, Enveloping aponeuroses: these are found round the limbs, where they maintain the muscles in their respective situ- ations, so that in great exertions the muscles are not liable to displacement; their inner surface often sends between the muscles fibrous partitions, which extend to the peri- osteum of the neighbouring bone ; and at the same time that they retain the muscular fibres in their situation, they give points for their insertion. Like the tendons, their hue is of a resplendent white ; in a healthy state they have little vascularity, and may be considered as destitute of sensibility. CHEMICAL COMPOSITION OF MUSCLES. Owing to the difficulty of separating the muscular fibres from the fat, blood, cellular membrane, etc. with which they are very intimately blended, the organic elements of the muscular tissue are still involved in obscurity; but MUSCULAR SYSTEM. 149 when freed as much as possible from those substances which adhere to them, they consist of albumen, a great quantity of fibrin, and a principle of a peculiar nature, co- loured, soluble in alcohol, giving to broth its taste and smell, named osmazome. There also occur in these organs a colouring matter, carbonate, hydrochlorate, and phos- phate of soda, phosphate of lime, and oxide of iron. SHEATHS OF TENDONS. In general these sheaths form a semi-cylindrical canal, completed by the bone in the opposite part in such a man- ner that the tendon slides in a canal, which is partly bony and partly fibrous; this canal is lined with a synovial membrane. On their external surfaces the fibrous sheaths correspond to the adjacent parts with which they are united, and adhere to them by loose cellular tissue. All the sheaths are composed of dense and strong fibres ; indeed, stronger than might be supposed to be sufficient to restrain the efforts of the tendons that act upon them ; the tendons are thus kept down in their proper places, and are pre- vented from deviating from their destined course. Some of these sheaths, as those at the wrist and on the instep, contain the united tendons of several muscles: these bear the name of annular ligaments; the tendons of the hand and foot having to pass a narrow space, it was indispensably necessary they should be there maintained. Other sheaths, as those of the fingers, are intended for a single tendon, or for two only. Besides these uses, the sheaths in some cases change the direction of the tendon, as we observe in the trochlea of the eye, and the sheaths of the tendons of the thumb and little finger. 1^0 MUSCULAR SYSTEM. STRENGTH OF MUSCLES. The natural strength of muscles probably depends on the number of fibres which enter into their composition; but the effect of habit and exercise of the muscles in giving strength, mobility, and dexterity, is astonishing. The muscles grow stronger in proportion to their being used, provided they are well used, and not exhausted by violence or over exertion : but the same muscles in differ- ent individuals, though of the same length and thickness, and as far as we are able to examine composed of the same number of fibres, are by no means uniform in the degree of power they are capable of exercising. Lender particu- lar excitement the muscular efforts may be carried to a wonderful degree: we know the strength of an enraged person, of maniacs, and of persons in convulsions; but such violent contractions cannot be carried beyond a certain time, after which a painful feeling of weariness takes place, which goes on increasing until the muscle refuses to act; by rest, however, the feeling of fatigue subsides, and the muscles recover their wonted energies. If, however, the brain of a man be compressed, the faculty of contract- ing the muscle ceases; the nerve of a muscle being cut, the muscle loses all power of contracting, thus showing that muscular action depends on the brain, and that it is gene- rally regulated, to a certain degree, by the willr. r " There are many muscles given to us which the common customs and habits of life seldom render it necessary to exert, and which, in consequence, grow stiff and immoveable. Tumblers and buffoons seem to be aware of this fact; and it is principally by the cultivation of these neglected muscles that they are able to assume those outrageous postures and gri- maces, and exhibit those feats of agility, which so often amuse and surprise us." Dr. Good's Book of Nature. MUSCULAR SYSTEM. 151 ACTIONS OF MUSCLES. Many muscles acting together, producing the same kind of motion, are called congeneres; those which act in the opposite direction are termed antagonistes. The first ordi- narily arise from the same fixed point or from the same region, the second or antagonists from the opposite. The various movements produced by the contraction of muscles are, adduction and abduction, flexion and exten- sion, and rotation, etc. These various motions are not usually effected by the action of one muscle alone, but by the co-operation of several congeneres. The flexors are commonly stronger than the extensors, and it is for this reason, that when the extremities are at rest, or in a state of freedom, or in paralysis, or during sleep, that they are bent or slightly flexed. And the flex- ors are attached further from the centre of motion than the extensors, and their direction is less parallel to the bone ; consequently the angle is more open, and the power more favourably applied. NOMENCLATURE OF THE MUSCLES. The denomination of the muscles is derived from seve- ral considerations, as, viz. from their Size, as great, small, long, broad, thin. Figure, as triangular, scalenus, deltoid, orbicular, rhom- boidal, etc. Direction, as straight, oblique, transverse. Composition, as complexus, triceps, biceps, semimem- branosus, perforans, etc. Attachment, as stylo-hyoideus, pterygoideus, sterno- cleido-mastoideus. Uses, as flexors, adductors, rotators, etc. CLASSIFICATION OF MUSCLES. The inconvenience from such a multiplicity of names from such different sources, has long been felt among ana- tomists, and many nomenclatures have been suggested to remove it. All the synonyms of muscles may be found in Lizars' System of Anatomy. CLASSIFICATION OF THE MUSCLES. The muscles have been distributed into classes, accord- ing to the different parts of the body which they occupy: each of these parts has received the name of a region. The following table presents a general view of the names and classification. TABLE OF THE MUSCLES. 153 CHAP. II TABLE OF THE MUSCLES. The total number of the muscles amount to 527, of which 257 are pairs, and lie on either side of the body. There are four single muscles situated on the middle line, independent of those muscles which perform the internal vital functions. MUSCLES OF THE HEAD. 1. Cranial region. 2. Auricular region. Occipito-frontalis. ' Attollens auris. Attrahens auris. Retrahens auris. MUSCLES OF THE FACE. 1. Palpebral region. 2. Ocular region. 3. Nasal region. 4. Su perior maxillary region. 5. In erior maxillary region. Orbicularis palpebrarum. Corrugator supercilii. Levator palpebral superioris. ' Rectus superior. Rectus inferior. ' Rectus internus. Rectus externus. 1 Obliquus superior. Obliquus inferior. Pyramidalis nasi. Compressor nasi. Levator labii superioris, alaeque nasi. Depressor alas nasi. Levator labii superioris. Levator anguli oris. Zygomaticus major. Zygomaticus minor. Orbicularis oris. Depressor anguli oris. Depressor labii superioris. Depressor labii inferioris. Buccinator. Levator menti. Masseter. VOL. I. 21 154 TABLE OF THE MUSCLES. 6. Temporo maxillary region. 7. Pterygo maxillary region. 8. Lingual region. 9. Palatine region. Temporalis. ( Pterygoideus externus. I Pterygoideus internus. /Hyo-glossus. l Genio-glossus. \ Stylo-glossus. ' Lingualis. f Circumflexus palati. I Levator palati. < Levator uvula?. [ Palato pharyngeus. ^Constrictor isthmi faucium. MUSCLES OF THE NECK. 1. Anterior cervical region. 2. Superior hyoidean region. 3. Inferior hyoidean region. 4. Pharyngeal region. 5. Deep cervical region. 6. Lateral cervical region. Platisma myoides. Sterno-cleido mastoideus. 'Digastricus. )Stylo-hyoideus. \ Mylo-hyoideus. ' Genio-hyoideus. C Omo-hyoideus. ; Stcrno-hyoideus. 1 Sterno-thyrioideus. k. Thyro-hyoideus. r Constrictor pharyngeus inferior. \ Constrictor pharyngeus medius. \ Constrictor pharyngeus superior. ' Stylo-pharyngeus. r Rectus capitis anticus major. c Rectus capitis anticus minor. ' Longus colli. f Scalenus anticus. {Scalenus posticus. £ Rectus capitis lateralis. MUSCLES OF THE TRUNK. 1. Anterior thoracic region. 2. Lateral thoracic region. 3. Intercostal region. 4. Diaphragmatic region. C Pectoralis major. < Pectoralis minor. £ Subclavius. Serratus magnus. /Intercostales oxterni. 1 Intercostales interni. \ Triangulares sterni. ' Levatores costarum. Diaphragma. TABLE OF THE MUSCLES. 165 MUSCLES OF THE ABDOMEN. 1. Abdominal region. 2. Lumbar region. 3. Anal region. 4. Genital region. Obliquus abdominis externus. Obliquus abdominis internus. Transversalis abdominis. Rectus abdominis. Pyramidalis. C Psoas magnus. i Psoas parvus. \ Iliacus internus. *Q,uadratus lumborum. C Levator ani. < Coccygeus. ( Sphincter ani. fist. (In the male.) Cremaster ischio- cavernosus. | Bulbo-cavernosus. i Transversus perinei. 2nd. (In the female.) Ischio-caver- nosus. Constrictor vagina?. MUSCLES OF THE POSTERIOR PART OF THE TRUNK. 1. Lumbo-dorsal region. 2. Dorso-cervical region. ( Trapezius. £ Latissimus dorsi. 'Rhomboideus. Levator anguli scapulae. Serratus posticus superior. Serratus posticus inferior. Splenius. Complexus. ^Tracnelo-mastoideus. f Rectus capitis posticus major. I Rectus capitis posticus minor. 3. Posterior occipito-cervical region*; Obliquus capitis superior. Obliquus capitis inferior. ^Interspinalis cervicis. 4. Vertebral region. f Longissimus dorsi. Sacro-lumbalis. ■i Transversus colli. Multifidus spina?. ^Intertransversales colli et lumborum. 156 TABLE OF THE MUSCLES. MUSCLES OF THE EXTREMITIES. Muscles of the Superior Extremities. MUSCLES OF THE SHOULDER. 1. Posterior scapular region. 2. Anterior scapular region. 3. External scapular region Supra-spinatus. Infra-spinatus. Teres minor. Teres major. Subscapulars. Deltoides. MUSCLES OF THE ARM. 1. Anterior brachial region. Coraco-brachialis. Biceps flexor cubiti. Brachialis internus. Triceps extensor cubiti. MUSCLES OF THE FORE-ARM. 1. Anterior region of the fore- arm. 2. Anterior deep region of the fore- arm. 3. Posterior superficial region of the fore-arm. 4. Posterior deep region of the fore-arm. Pronator teres. Flexor carpi radialis. Palmaris longus. Flexor carpi ulnaris. Flexor digitorum sublimis vel perfo- ratus. Flexor digitorum profundus vel per- forans. Flexor longus pollicis manus. Pronator quadratus. Extensor digitorum communis. Extensor proprius minimi digiti. Extensor carpi ulnaris. Anconeus. Extensor ossis metacarpi pollicis. 1 Extensor primi et secundi internodii i pollicis manus. Indicator. TABLE OF THE MUSCLES. 157 MUSCLES OF THE HAND. 1. External palmar region. 2. Internal palmar region. 3. Middle palmar region. > Interossei. « Abductor brevis pollicis manus. Opponens pollicis. Flexor brevis pollicis manus. Adductor pollicis manus. Palmaris brevis. Abductor minimi digiti. Flexor proprius minimi digiti. Adductor ossis metacarpi minimi digiti. Lumbricales. '1. Abductor indicis. 2. Adductor indicis. 3. Abductor digiti medii. 4. Adductor digiti medii. 5. Abductor digiti annularis. 6. Adductor digiti annularis. 7. Abductor minimi digiti. MUSCLES OF THE INFERIOR EXTREMITY. MUSCLES OF THE HAUNCH AKD THIGH. 1. Region of the hip. 2. Pelvi-trochantric region. 3. Anterior femoral region. 4. Internal femoral region. 5. Posterior femoral region. C Gluteus maximus. < Gluteus medius. ( Gluteus minimus. (P)'riformis. Obturator internus. Obturator externus. Gemellus superior. Gemellus inferior. Quadratus femoris. C Sartorius. < Rectus femoris. ( Triceps extensor cruris. 'Pectineus. Gracilis. Adductor longus. Adductor brevis. ^ Adductor magnus. Biceps femoris. Semitendinosus. Semimembranosus. 158 TABLE OF THE MUSCLES. MUSCLES OF THE LEG. (Tibialis anticus. Peroneus tertius. Externus longus digitorum pedis ^Extensor proprius pollicis pedis. C Peroneus longus. \ Peroneus brevis. C Gastrocnemius externus. Gastrocnemius internus. J Soleus. ! Plantaris. Popliteus. Flexor longus digitorum pedis. Tibialis posticus. [^Flexor longus pollicis pedis. 2. Peroneal region. 3. Posterior region of the leg. MUSCLES OF THE FOOT. 1. Dorsal region. 2. Plantar region. Extensor brevis digitorum pedis. Interossei externi. 'Flexor brevis digitorum pedis. Abductor pollicis pedis. Abductor minimi digiti pedis. Flexor digitorum accessorius. Lumbricalis pedis. Flexor brevis pollicis pedis. Adductor pollicis pedis. Flexor brevis minimi digiti pedis. Transversus pedis. Interossei interni. MUSCULAR SYSTEM OF THE HEAD. 159 MUSCLES OF THE HEAD. Cranial Region. OCCIPITO-FRONTALIS. Fig. 109. This is the only muscle which properly belongs to the scalp ; it consists of two distinct parts, an anterior and a posterior, which are united by an aponeurosis or tendi- nous membrane. The posterior portion, a, has an apon- eurotic and fleshy attachment to the transverse ridge of the occipital bone ; it forms, b, the cranial aponeurosis, a broad fibrous expansion which covers the whole upper part of the cranium: the anterior portion, seen in Fig. Ill, a, is attached to c, the circular muscle of the eyelid, and to the skin; and by b, to the inner angle of the frontal bone, and the os nasi. The outer surface of this muscle is co- vered by the integuments, the inner rests on the cranium. The anterior portion of this muscle raises the brow, 160 MUSCULAR SYSTEM wrinkles the forehead, and brings forward the integuments of the head; the posterior draws back the skin to its ori- ginal situation. The direction of the muscular fibres and the aponeurosis are also seen, Fig. 112, a, 6s. AURICULAR REGION. ATTOLLENS AURIS. Fig. 112. The attollens auris, c, is of a triangular figure, situated on the temple above the ear; superiorly it is at- tached to the cranial aponeurosis, and inferiorly to the car- tilage of the ear. The outer surface of this muscle is co- vered by the skin, the inner covers the temporal aponeurosis. The action of this muscle raises the ear. ATTRAHENS AURIS. The attrahens auris, d, is situated before the ear, and has the same form as the preceding; anteriorly it is at- tached to the border of the cranial aponeurosis, and pos- teriorly to the cartilage or anterior helix of the ear. This muscle draw's the ear forward and upward. The outer surface of this muscle is covered by the skin; the inner is situated upon the temporal muscle and tem- poral artery. RETRAHENS AURIS. This muscle, e, is situated behind the ear, and is ex- tended from the mastoid process of the temporal bone to the back of the ear. It frequently consists of two small bundles of fibres, and is then described as two muscles. 6 This is sometimes divided by anatomists into two muscles, the occipital and frontal muscles. OF THE HEAD. 161 This muscle is covered by the integuments, and is sepa- rated from the temporal bone by cellular tissue. The action of this muscle carries the ear backwards'. MUSCLES OF THE FACE. PALPEBRAL REGION. ORBICULARIS PALPEBRARUM. Fig. Ill, c, Fig. 112,/. The fleshy fibres of this muscle surround the orbit of the eye, and form part of the eyelids ; superiorly it is at- tached to the frontal bone, and inferiorly to the superior maxillary bone, where it has a tendinous point of insertion into the nasal process. The anterior surface of this muscle is covered by the integuments; the posterior is applied upon the corrugator supercilii, the fibro-cartilage of the upper eyelid, the malar bone, the muscles of the superior maxillary region, the ligament and fibro-cartilage of the lower eyelid, the ascend- ing process of the superior maxillary bone, and the lachry- mal sac. This muscle shuts the eye, by bringing down the upper eyelid and raising the lower, the fibres contracting towards the inner angle ; it also depresses the eyebrow at the same time it raises the cheek. CORRUGATOR SUPERCILII. Fig. 111. This muscle, p, is placed on the arch of the orbit, in the thickness of the eyebrow; it is attached on the one part to the superciliary ridge, and on the other to the occipito- frontalis and orbicularis muscles. t The other muscles of the ear will be described with the organ of hearing. vol. i. 22 162 MUSCULAR SYSTEM The anterior surface of this muscle is covered by the orbicularis palpebrarum, the occipito-frontalis, and the "pyramidalis nasi muscles; the posterior is in contact with the frontal bone, the superciliary artery, and the frontal branch of the ophthalmic nerve. This muscle draws down the brow in the expressions of anger and the malevolent passions. LEVATOR PALPEBRiE SUPERIORIS. Fig. HO. 4 This muscle, a, is situated in the superior part of the orbit, and is fixed to the bottom of it; it is then spread out into a broad tendon, which is attached to the cartilage of the upper eyelid, as is seen also in Fig. Ill, n. The superior surface of this muscle is connected with the orbit and frontal branch of the ophthalmic nerve ; and OF THE HEAD. 163 more anteriorly it is separated from the orbicularis palpe- brarum by the palpebral ligament; the inferior is con- nected with ,the rectus superior and conjunctiva. The action of this muscle raises the upper eyelid, OCULAR REGION. RECTUS SUPERIOR. Fig. 110. This muscle, b, is situated in the orbit above the eye, under the levator palpebrae; it is broad and thin, tendinous at its extremities, and fleshy in the rest of its extent. Pos- teriorly it is attached to the optic foramen, and anteriorly to the sclerotica. The superior surface of this muscle is covered by the preceding ; the inferior is placed upon the optic nerve, the ophthalmic artery, and the nasal branch of the ophthalmic nerve, in front upon the eye itself. The action of this muscle raises the eye. RECTUS INFERIOR. The figure and structure of d, the rectus inferior, is like the preceding; posteriorly it is attached to the inferior part of the optic foramen, and anteriorly to the sclerotica. The inferior surface of this muscle is separated from the floor of the orbit by adipose tissue; the superior is in connection with the optic nerve, a branch of the third pair of nerves, and the eye. This muscle is the antagonist to the rectus superior, and draws the eye downwards. 164 MUSCULAR SYSTEM RECTUS INTERNUS. This muscle, c, c, is similar to the two described; it is situated on the inner side of the eye, and is attached pos- teriorly to the margin of the optic foramen ; anteriorly, to the inner side of the eye. In this figure the central part is removed to show k, the optic nerve, but its attachments are preserved. This muscle draws the eye towards the nose. RECTUS EXTERNUS. The rectus externus is similar in its figure and attach- ments to the other recti, but is situated on the outer side of the eye. In this figure the muscle is supposed to be removed. The outer surface of this muscle is in apposition with the orbit and lachrymal gland; the inner with the optic nerve, the sixth pair, and the lenticular ganglion. The office of this muscle is to carry the eye outward- / OBLIQ.UUS SUPERIOR. This muscle, e, is situated at the internal and superior part of the orbit; posteriorly it is attached to the optic fo- ramen, passes forward horizontally to the internal orbitar process, where it forms a thin round tendon, which passes through f, a cartilaginous ringu ; runs obliquely downwards and backwards, and is inferiorly attached at g, by a radi- ated tendon, to the globe of the eye. On the inside of the pulley or ring is a synovial capsule, which is reflected over the tendon. u At least this loop forms a ring with the superciliary notch. OF THE HEAD. 165 This muscle is situated between the orbit and the optic nerve, the superior and internal recti muscles, and the globe of the eye. The office of this muscle is to roll the eye, and to turn the pupil downwards and outwards. OBLIQ.UUS INFERIOR. This muscle is situated at the anterior part of the orbit. Anteriorly it is attached at i, the inner edge of the orbitar process of the superior maxillary bone, near its union with the os unguis; it is directed backwards and outwards, under d, the rectus inferior, and is attached posteriorly by h, a thin tendon, to the sclerotic membrane. The inferior surface of this muscle is placed on the floor of the orbit; the superior corresponds with the ball of the eye, and with the rectus inferior. By means of the inferior oblique muscle the eye is turned upwards and inwards. 166 MUSCULAR SYSTEM NASAL REGION. PYRAMIDALIS NASI. Fig. 111. This muscle, b, is confounded with the occipito-fronta- lis ; its figure is thin and triangular; it is attached by its summit to the last-named muscle, covers the nasal bones, and is fixed by its base to the compressor nasi. This muscle is sometimes regarded as merely a portion of the frontal muscle; the upper part is certainly intermixed with it, but the lower part is very distinct. The anterior surface is connected with the skin; the posterior with the corrugator supercilii, the os frontis, and the proper bones of the nose. This muscle assists in bringing down the integuments of the forehead, and in raising the skin of the nose. OF THE HEAD. 167 COMPRESSOR NASI. Fig. 112. This muscle, Fig. Ill, o, Fig. 112, h, is attached on the outer side of the cartilage of the nose to the adjacent part of the superior maxillary bone, and on the inner side to the bridge of the nose, where it meets its fellow. The anterior surface is covered by the skin, the poste- rior lies upon the superior maxillary bone and upon the lateral cartilage of the nose. This muscle compresses the nostrils; it sometimes acts with the pyramidal and frontal muscle, to which it is con- nected, and then it raises the nostril. LEVATOR LABII SUPERIORIS ALJEQ.UE NASI. This muscle, Fig. 112, i, is attached by a small tendon to the nasal process of the superior maxillary bone, close 168 MUSCULAR SYSTEM by the tendon of the orbicular muscle of the eyelids; as it approaches the nose it is spread out into two portions, one of which is inserted into the ala or cartilage of the nostril, the other into the upper lip. The anterior surface is placed beneath the skin, and at its upper part it is concealed by the orbicularis palpebra- rum. The posterior is connected with the preceding mus- cle, the nasal process of the superior maxillary bone, the border of the levator labii superioris, and the depressor nasi. This muscle raises the ala of the nostril and upper lip. DEPRESSOR ALJG NASI. This muscle, Fig. 113, e, is a small fleshy fasciculus, placed beneath the ala or wing of the nose. Superiorly it is attached to it; inferiorly to the superior maxillary bone immediately above the upper incisor teeth. The fibres of this muscle are covered by those of the levator labii superioris alaeque nasi, and by the mucous membrane of the mouth, and are applied to the superior maxillary bone. The contraction of this muscle depresses the ala of the nose. SUPERIOR MAXILLARY REGION. LEVATOR LABII SUPERIORIS. This muscle, Fig. 112, k, is situated in the middle of the face ; superiorly it is attached to the lower part of the orbit, inferiorly to the upper lip ; it contracts as it descends, and its fibres are confounded with the circular muscle of the lips, between the nose and angle of the mouth. At the upper part, this muscle is covered by the OF THE HEAD. 169 orbicularis palpebrarum, and at the lower part by the skin. The posterior surface is in connection with the levator anguli oris, from which it is separated by the infra-orbitar vessels and nerves. LEVATOR ANGULI ORIS. This muscle, Fig. 112, I, is situated near the middle of the face; superiorly it is attached to the canine fossa; inferiorly to the angle of the lips. The anterior surface is connected, as we see in the figure, with other muscles of the face ; the posterior sur- face with the canine fossa, the mucous membrane of the mouth, and the buccinator muscle. This muscle raises the angle of the mouth. ZYGOMATICUS MAJOR. This is a long and slender muscle, Fig. Ill, f, Fig. 112, m, situated on the side of the face, and passing down- wards and inwards; superiorly it is attached to the upper part of the cheek bone ; inferiorly to the corner of the mouth. ZYGOMATTCUS MINOR. This muscle, Fig. Ill, e, Fig. 112, n, is not found in all subjects. It is situated on the inner side of the pre- ceding muscle between k, the elevator of the upper lip, and m, the great zygomatic muscle. It passes in the same direction as the last-mentioned muscle, and has nearly the same attachments. The anterior surface of the zygomatic muscles is gene- rally covered by a great quantity of fat as well as skin; the vol. i. 23 170 MUSCULAR SYSTEM posterior surfaces are placed on the malar bone and the buccinator muscle; their connection with the other mus- cles of the face is obvious in the figure. The zygomatic muscles raise the angle of the mouth, as in laughing, etc. ORBICULARIS ORIS. The form of this muscle, Fig. Ill, i, Fig. 112, t, is elliptical; its fibres are found in the substance of the lips, and is completely interlaced and confounded with those other muscles which terminate near the angle of the mouth. The skin adheres firmly to the anterior surface of this muscle ; the posterior surface is lined by the mucous mem- brane of the mouth, and its free edge is invested by the red membrane of the lips. The connection with the other muscles of the face is intricate. This muscle is as an antagonist to the other muscles of the lips; it is a true sphincter muscle, contracting the aperture of the mouth ; its action is evident in playing the flute, in sucking, in masticating, he. INFERIOR MAXILLARY REGION. DEPRESSOR ANGULI ORIS. This muscle, Fig. Ill, k, Fig. 112, o, is of a triangular form, situated at the lower part of the face; superiorly it is attached to the lower jaw; inferiorly to the angle of the mouth, where the fibres are confounded with those of the levator angulis oris. The outer surface adheres to the skin and the platysma myoides; the inner is connected with the buccinator and the depressor labii inferioris. This muscle depresses the angle of the mouth, and its action expresses grief. OF THE HEAD. 171 DEPRESSOR LABII INFERIORIS. This muscle, Fig. Ill, m, Fig. 112, p, is thin, and nearly quadrilateral; its situation in the face is obvious in the figures referred to. Inferiorly it is attached to the lower jaw; superiorly to the lower lip, where its fibres are con- founded with the orbicularis. The anterior surface is connected with the skin and part of the preceding muscle. The posterior surface is con- nected with the lower jaw, the mental vessels and nerves, the levator menti, and the labial muscles. The use of this muscle is to pull the lip downwards. BUCCINATOR. This muscle, Fig. 112, s, is situated in the cheek; supe- riorly it is attached to the sockets of the molar teeth of the upper jaw; inferiorly to the corresponding part of the lower jaw ; behind, it is connected with the constrictor muscle of the pharynx, and in front with the angle of the mouth. The middle fibres are horizontal, the superior and inferior a little converging to the angle of the lips. It is perforated in the middle by the duct of the parotid gland. The outer surface is covered by a thick layer of fat, the zygomaticus major, the platysma myoides, the depressor anguli oris, the skin, and the labial artery and vein. The inner is lined by the mucous membrane of the mouth. This muscle is seen remarkably dilated in blowing the horn or trumpet: its use is to force the air out of the mouth by contracting its cavity, to draw the angle of the mouth backwards, and in mastication to press the food within the line of the teeth. 172 MUSCULAR SYSTEM LEVATOR MENTI. This muscle, Fig. 112, r, is placed on the chin; supe- riorly it is attached to the depression on the side of the symphysis of the jaw, under the alveoli of the incisor teeth. The fibres diverge downwards, and are inserted into the skin of the chin. Anteriorly it is covered by the skin; posteriorly by the mucous membrane of the mouth. This muscle raises the chin. MASSETER. This muscle, Fig. Ill, h, Fig. 112, v, is composed of aponeurotic and fleshy fibres, situated on the side of the face ; it is very thick, and attached superiorly to the two anterior thirds of the inferior part of the zygomatic arch, to its internal surface, and to the aponeurosis of the tem- poral muscle ; inferiorly to the angle of the lower jaw, to its external surface, and to the inferior border of the ramus of the same. The masseter is sometimes described as two distinct portions which decussate one another; the anterior portion running backwards, is fixed into the side of the lower jaw as far as the angle; the posterior portion passing forwards, is united to the coronoid process. On the outer side is found the parotid gland and its duct, the platysma myoides, the facial nerve, the transverse facial artery, etc. The inner surface is placed on the ramus of the inferior maxilla, the tendons of the temporal, and the buccinator muscles. This muscle raises the lower jaw, and acts powerfully during mastication. OF THE HEAD. 173 TEMP0R0 MAXILLARY REGION. TEMPORALIS. Fig. 113. The situation and direction of the fibres of this muscle is described in the annexed figure : a portion of c, the zygoma, is removed to show the whole of the muscle. It occupies the whole temporal cavity, and is covered with a strong aponeurosis, while another is placed in the midst of the fleshy fibres, dividing it into two planes, terminating inferiorly in a strong tendon. It is attached superiorly to the temporal fossa, and to a, a, b, the semicircular line bounding it; inferiorly at d, the coronoid process of the inferior maxilla. The outer surface of the temporal muscle is covered by the epicranial aponeurosis, the superior and anterior auri- cular muscles, and a portion of the orbicularis palpebrarum and masseter muscles ; the superficial temporal vessels and nerves also ramify over it. The inner surface is situated 174 MUSCULAR SYSTEM upon the temporal fossa and the internal maxillary artery. The pterygoideus externus, and buccinator muscles, are separated from it by a considerable quantity of fat. The office of this muscle, as well as the preceding, is to draw the lower jaw upwards. In carnivorous animals the temporalis is the strongest muscle in the whole body. PTERYGO-MAXILLARY REGION. PTERYGOIDEUS EXTERNUS. Fig. 114. This muscle is situated in the zygomatic fossa; it is at- tached by one portion at b, c, to the external surface of the pterygoid process, and by the other to the zygomato-tem- poral surface of the sphenoid bone; from thence the mus- cle is directed outwards and backwards, and is inserted into a, the anterior part of the neck of the condyle of the lower jaw, and into the fore part of the circumference of the interarticular cartilage. OF THE HEAD. 175 The outer surface is in contact with the temporal muscle, and frequently with the internal maxillary artery. The inner surface corresponds with the pterygoideus in- ternus, the inferior maxillary nerve, and the middle men- ingeal artery. The upper surface touches the zygomatic fossa and the deep temporal and masseteric nerves. This muscle brings forward, and to the opposite side, the condyle of the jaw, and the interarticular cartilage ; when the pair of muscles act together, the jaw is drawn directly forwards. PTERYGOIDEUS INTERNUS. This muscle, d, is placed at the inner and posterior part of the branch of the inferior maxillary bone. It is at- tached superiorly by tendinous and fleshy fibres to the inner plate of the pterygoid process of the sphenoid bone, and to the pterygoid process of the os palati, filling all the space between the two plates : inferiorly it is attached by tendinous and fleshy fibres to the inside of the angle of the lower jaw. The inner surface is connected with the circumflexus palati, the constrictor pharyngis superior, and the sub- maxillary gland. The outer surface lies upon the inner part of the branch of the lower jaw, much in the same manner as the masseter does upon the outer part. When the pair of muscles act together, they bring the jaw horizontally forwards; when they act singly, the jaw is moved obliquely to the opposite side. The pterygoid muscles move the jaw from side to side, and perform the motion of grinding with the teeth. 176 MUSCULAR SYSTEM LINGUAL REGION. HYO-GLOSSUS. Fig. 115. This muscle, d, is situated at the front and upper part of the neck ; it is thin, flat, and quadrilateral. Inferiorly, its fibres are attached to the os hyoides; superiorly, to the side of the tongue, and mixes with a, e, the fibres of the stylo-glossus. The outer surface is covered by the hyo-glossus, the mylo-hyoideus, the genio-hyoideus and digastricus, the hypo-glossal nerve, and the sub-maxillary gland. The inner surface is connected with the constrictor pharyngis medius, the genio-glossus, the lingual artery, and the glosso- pharyngeal nerve. The hyo-glossus draws the tongue inwards and down- wards. GENIO-GLOSSUS. This~muscle, i, k, is situated between the tongue and I, the lower jaw; its fibres are radiated, extending from the OF THE HEAD. 177 mental process to the inferior surface of the tongue and the os hyoides. The external surface of the genio-glossus is connected with the sublingual gland, and the stylo-glossus, hyo-glos- sus, lingualis, and mylo-hyoideus muscles; the internal surface is in contact with that of the opposite side. According to the direction of its fibres, so it moves the tongue : those which go to the point draw it backwards; those which pass backwards thrust the tongue out of the mouth ; and the central fibres have the power of rendering the upper surface of the tongue concave. STYLO-GLOSSUS. This muscle takes an oblique direction from above, where it is attached, at a, to the styloid process of the temporal bone, and to f the stylo-maxillary ligament; the muscular fibres are finally lost, at e, in the substance of the tongue. The outer surface is covered by the digastricus, the lin- gual nerve, the submaxillary gland, and the mucous mem- brane of the mouth: the inner surface covers the constric tor pharyngis superior, the hyo-glossus, and the lingualis. The stylo-glossus moves the tongue sideways and back- wards, when it acts alone; but when it contracts at the same time with the corresponding muscle, the tongue is carried upwards and backwards. LINGUALIS. The fibres of this muscle run#from the root to the tip of the tongue, and are intermixed at its lateral parts with the muscles just mentioned. vol. i. 24 178 MUSCULAR SYSTEM The upper surface is confounded with the fleshy tex- ture of the tongue ; the lower surface is covered by the mucous membrane of the mouth. This muscle contracts the tongue and depresses its point. PALATINE REGION. CIRCUMFLEXUS PALATI. Fig. 116. This muscle is placed in the substance of the velum of the palate. Superiorly it is attached to the wing of the OF THE HEAD. 179 sphenoid bone and to the Eustachian tube; its tendon, /, passes round the hook of the internal plate of the ptery- goid process of that bone, and spreads into g, a tendon at the semilunar edge of the os palati and velum palati. The external surface is covered by the pterygoideus in- ternus ; the inner surface is in apposition with the levator palati and constrictor pharyngis superior, the mucous mem- brane of the pharynx and of the velum palati. This muscle stretches the palate horizontally. LEVATOR PALATI. The shape and direction of this muscle, b, b, is apparent in the figure. Superiorly it is attached at m, the petrous portion of the temporal bone; the inferior fibres are in- serted into a, the pendulous part of the palate, its fibres being confused with the other muscles in that situation. The outer surface is connected with the circumflexus palati, the palato-pharyngeus, and the constrictor pharyngis superior; the inner is lined by the mucous membrane of the pharynx and of the velum palati. This muscle draws the curtain of the palate upwards and backwards in the time of swallowing, and thus pre- vents the food or drink from passing into the nose. LEVATOR UVULiE. This muscle, a, occupies the substance of the uvula, or that small fleshy substance hanging in the middle of the palate. The uvula muscle is one of the four instances of a single muscle ; it is attached to the palate bones, and runs down the whole length of the uvula, adhering to the tendons of g, the circumflex muscle. 180 MUSCULAR SYSTEM It is connected anteriorly with the levator palati, and is covered posteriorly by the membrane of the velum palati. This muscle raises the uvula. PALATO-PHARYNGEUS. This muscle is placed in the substance of the velum palati and that of the pharynx; superiorly it is attached, at c, to the arch of the palate; inferiorly, at d, to the thy- roid cartilage, and the bag of the pharynx. The posterior surface of this muscle is covered by the mucous membrane of the velum palati, and the constric- tores pharyngis; the anterior surface is connected with the aponeurosis of the circumflexus palati and the mucous membrane of the pharynx. This muscle draws the uvula downwards and backwards, shuts the passage of the posterior nostrils, and assists in swallowing. CONSTRICTOR ISTHMI FAUCIUM. This is a small fleshy fasciculus, h, attached to the cur- tain of the palate and to the base of the tongue. The action of this muscle lowers the velum palati, and assists in raising the tongue. OF THE NECK. 181 CHAP. III. MUSCLES OF THE NECK. ANTERIOR CERVICAL REGION. PLATYSMA MYOIDES. Fig. 117. This is an extremely thin layer of fleshy fibres, spread over the other muscles, and attached to the cellular mem- brane of the neck; it requires some skill in dissection to display this muscle, for as it is merely a web of muscular fibres, it is frequently removed with the integuments un- noticed. Superiorly it extends to a, the face, where its fibres are lost in the cellular tissue of the cheek, and 182 MUSCULAR SYSTEM inferiorly at b; its fibres cover a portion of c, the pectoral, and of d, the deltoid muscles. The outer surface of this muscle is covered by the skin ; the inner is placed over the deltoides, pectoralis major and sterno-cleido-mastoideus muscles, the clavicle, the muscles of the hyoidean and maxillary regions, and the submaxillary and parotid glands. This muscle draws the skin of the cheek downwards, and when the mouth is shut, brings the skin under the lower jaw upwards. STERNO-CLEIDO-MASTOIDEUS. Fig. 118. This muscle is situated at the side of the neck. Supe- riorly it is attached, at a, to the mastoid process of the temporal bone, and to a part of the occipital bone; inferi- orly, at b, to the summit of the sternum, and at c, to the internal third of the superior border of the clavicle. The outer surface is covered by the platysma myoides, excepting at its upper extremity, which lies under the skin OF THE NECK. 183 and parotid gland; between it and the preceding muscle the external jugular vein and some nervous filaments of the cervical plexus are situated. The inner surface is connected to the articulation of the sternum with the cla- vicle, the sterno-thyroideus, sterno-hyoideus, and omo-hy- oideus muscles, the internal jugular vein, the carotid artery, the pneumo-gastric nerve, the cervical plexus, the great sympathetic nerve, the scaleni, the levator scapulae, the splenius and digastric muscles. DIGASTRICUS. This muscle is so called from having two bellies, g, g, one of which is attached to the mastoid groove of the tem- poral bone, and becomes tendinous in the middle, travers- ing a perforation in h, the stylo-hyoideus muscle; the other is inserted into the inner part of the chin, Fig. 119, h. The central tendon is braced down by aponeurotic fibres to d, the os hyoides. The outer surface is covered by the lesser complexus, splenius, and sterno-cleido-mastoideus muscles; the sub- maxillary gland is lodged in the angle formed by the ten- don. The inner surface is placed upon the stylo-hyoideus, the stylo-glossus, and the stylo-pharyngeus muscles, the external and internal carotid arteries, the internal jugular vein, the hypo-glossal nerve, and the hyo-glossus and mylo-hyoideus muscles. When the mouth is shut the action of this muscle raises the os hyoides, and the pharynx at the time of deglutition; when these parts are fixed it opens the mouth. STYLO-HYOIDEUS. The form of this muscle, Fig. 118, h, is long and slen- der, having a tendinous attachment superiorly to the styloid 184 MUSCULAR SYSTEM process, and inferiorly to d, the os hyoides. Its perforation to admit the tendon of the digastricus has been mentioned in the preceding description of that muscle, and is also represented in Fig. 115. The digastric muscle is extended across the outer sur- face; the inner "is connected with the external carotid, labial, and lingual arteries, the internal jugular vein, the stylo-glossus, stylo-pharyngeus, and hyo-glossus muscles, and the hypo-glossal nerves. MYLO-HYOIDEUS. This is a broad, thin, triangular muscle, Fig. 115, i; superiorly it is attached to nearly the whole extent of the inside of the lower jaw, between the molar teeth and the chin; inferiorly the fibres converge, and are inserted into the os hyoides. This muscle unites with its fellow in a mid- dle line, which extends from the os hyoides to the chin. The outer surface is covered by the digastricus, the platysma myoides, and the submaxillary gland; the inner is placed in contact with the genio-hyoideus, genio-glossus, and hyo-glossus, the sub-lingual gland, the prolongation of this gland, and the lingual nerve. This muscle raises the os hyoides, or depresses the jaw. GENIO-HYOIDEUS. This muscle, Fig. 115, k, Fig. 119, i, is placed above the preceding; its figure is thin and narrow. Anteriorly it is attached to the mental process of the lower jaw ; pos- teriorly to the surface of the body of the os hyoides. The anterior surface is covered by the mylo-hyoideus; the posterior is in contact with the genio-glossus and hyo- glossus ; the inner edge meets that of the opposite side. The action of this muscle raises the os hyoides, carrying it forward, or it depresses the lower jaw. OF THE NECK. 185 INFERIOR HYOID REGION. OMO-HYOIDEUS. Fig. 119. This muscle, c, c, and in the preceding figure, e, e, is situated at the side of the neck; it is very long, thin, and narrow. Superiorly it is attached to the hyoid bone, des- cends obliquely across the neck, and forms a tendon in its centre, where it passes behind the sterno-cleido-mastoi- deus, and becoming fleshy again, is inserted into the root of the coracoid process and semilunar notch of the scapula. The outer surface is covered by the trapezius, the pla- tysma myoides, and the sterno-cleido-mastoideus; we see in the figure the clavicle lying across it. The inner sur- face corresponds to the scaleni muscles, the anterior bran- ches of the inferior cervical nerves, the primitive carotid vol. i. 25 186 MUSCULAR SYSTEM artery, the internal jugular vein, the superior thyroidean vessels, the sterno-hyoideus and sterno-thyroideus muscles. This muscle depresses the hyoid bone, drawing it a little backwards. STERNO-HYOIDEUS. This is a long, thin muscle, Fig. 119, b, presenting generally towards its middle an aponeurotic intersection. Superiorly it is attached to the body of the hyoid bone; inferiorly to the superior part of the sternum, the clavicle, and sometimes to the first rib. The clavicle passes across the anterior surface of this muscle, and it is covered by the sterno-cleido-mastoideus, the omo-hyoideus, the platysma-myoides, and by the com- mon integuments. The posterior surface is in apposition with the sterno-thyroideus, crico-thyroideus, and thyro- hyoideus muscles, the thyro-hyoid membrane, the thyroid gland, and the superior thyroid vessels. This muscle depresses the larynx, and furnishes a fixed point for the depressors of the jaw. STERNO-THYROIDEUS. This muscle, d, is placed behind the former, and its form is like it; superiorly it is attached to the thyroid car- tilage ; inferiorly to the upper and posterior part of the sternum, opposite the cartilage of the first rib. It fre- quently presents at its lower part an oblique or transverse aponeurotic intersection. The anterior surface is covered by the sterno-hyoideus, sterno-cleido-mastoideus, and omo-hyoideus muscles. The posterior surface covers the subclavian and internal jugular veins, the primitive carotid artery, the trachea, the-thyroid OF THE NECK. 187 gland, the crico-thyroid muscle, and a part of the constric- tor pharyngis inferior. This muscle draws the larynx downwards. THYRO-HYOIDEUS. This is a small oblong muscle, e, attached superiorly to the hyoid bone, inferiorly to the thyroid cartilage. The anterior surface of this muscle is covered by the sterno-hyoideus, the omo-hyoideus, and the platysma my- oides ; the posterior lies upon the thyroid cartilage, and the thyro-hyoid membrane. This muscle brings the larynx and hyoid bone towards each other. 188 MUSCULAR SYSTEM PHARYNGEAL REGION. CONSTRICTOR PHARYNGEUS INFERIOR. Fig. 120. This is the largest muscle, c, of the pharynx. It is broad and membranous; anteriorly it is attached to h, the thyroid and cricoid cartilages, and to-*, the upper rings of the trachea; posteriorly it is united to its fellow, in a ver-. tical tendinous line. The direction of its fibres is express- ed in the figure. 7503 OF THE NECK. 189 The exterior surface is covered by the sterno-thyroi- deus, the thyroid gland, and the primitive carotid artery. The posterior surface i* connected ' th the rectus capitis, anticus major and longus colli m^^LcS, and with the ante- rior vertebral ligament by cellular tissue. The interior surface is covered by the constrictor medius, palato-pha- ryngeus, and the stylo-pharyngeus muscles, the mucous membrane of the pharynx, and the thyroid and cricoid cartilages. This muscle contracts that part of the pharynx which it covers. CONSTRICTOR PHARYNGIS MEDIUS. This muscle, b, is of a triangular shape, situated at the middle part of the pharynx. It is attached anteriorly to the greater and lesser cornea of g, the hyoid bone, and to the stylo-hyoidean ligaments; posteriorly to its fellow, in a tendinous line at the back of the pharynx, and superiorly it is fixed to the basilar process of the occipital bone. Observe the direction of its fibres in the figure. This muscle is connected on its outer surface with the hyo-glossus muscle and the lingual artery, and by the inferior constrictor below; in the rest of its extent it is connected with the muscles of the deep cervical region and the anterior vertebral ligament. The inner surface is covered by the mucous membrane of k, the pharynx, the stylo-pharyngeus, palato-pharyngeus, and the superior con- strictor muscles. This muscle compresses that part of the pharynx which it invests. CONSTRICTOR PHARYNGIS SUPERIOR. Like the other constrictors, this muscle, a, is broad and thin; its figure is nearly quadrilateral. It is partly covered 190 MUSCULAR SYSTEM by the middle constrictor, and its connections are most extensive. Superiorly, it is attached to the occipital bone before the large for£U °n; lower down, to the pterygoid process of the spheno^^Done, to the upper and under jaw near the last molar teeth, and to d, the buccinator muscle. Some fibres also are fixed to the root of the tongue and palate. Posteriorly, like the two preceding, its fibres are united in a line to the corresponding muscle. The outer surface is connected with the preceding mus- cle, the stylo-glossus, the stylo-pharyngeus, the internal carotid artery, the internal jugular vein, the pneumo-gas- tric, hypo-glossal, and spinal nerves. These different parts occupy a triangular space, which is found between the constrictor pharyngis superior and the pterygoideus internus. The inner surface is connected with the palato- pharyngeus and the levator palati, and is lined by the mucous membrane of the pharynx. This muscle compresses the pharynx at the upper part; the constrictors act in succession, and contract that portion of the alimentary canal when it is filled with food, and force it downwards into the esophagus. OF THE NECK. 191 STYLO-PHARYNGEUS. This muscle is situated at Fig. 121. the side and back part of the pharynx; it is attached supe- riorly to a, the styloid process, and inferiorly it is expanded on the pharynx and back part of the thyroid cartilage. The outer surface is co- vered by the stylo-hyoideus, constrictor medius, and ex- ternal carotid artery; the inner is connected with the internal carotid artery, the internal jugular vein, the mu- cous membrane of the pha- rynx, and the superior con- strictor and palato-pharyngeus muscles. This muscle raises the pharynx, and also draws upwards the thyroid cartilage. DEEP CERVICAL REGION. RECTUS CAPITIS ANTICUS MAJOR. This muscle, Fig. 122, a, is placed on the anterior and lateral part of the cervical column ; superiorly it is attached to the basilary process of the occipital bone ; inferiorly by small tendons to the anterior tubercle of the transverse processes of the third, fourth, fifth, and sixth cervical ver- tebra?. It is a little drawn aside in the figure to show the muscle to be next described. The anterior surface corresponds to the carotid artery, 192 MUSCULAR SYSTEM the internal jugular vein, the pneumo-gastric nerve, the superior cervical ganglion, and the pharynx; the posterior surface covers the longus colli, the rectus capitis anticus minor, the articulations of the atlas with the occiput, the articulation also of the axis or dentatus with the atlas, and also the transverse process of the cervical vertebrae. If this muscle acts in conjunction with that of the oppo- site side, it bends the head forward; and laterally, if it acts by itself. RECTUS CAPITIS ANTICUS MINOR. Fig. 122. This is a small and thin muscle, c, situated close to the uppermost vertebra ; it is tendinous at its insertions, apon- eurotic at its anterior surface, fleshy in the rest of its ex- tent. Superiorly it is attached to the occipital bone near the condyle ; inferiorly to the atlas, or first vertebra. OF THE NECK. 193 It is connected anteriorly with the preceding muscle ; posteriorly with the articulation of the atlas and occiput. This muscle assists the preceding in supporting or bend- ing the head. LONGUS COLLI. This muscle, b, b, lies behind the esophagus, and the great vessels and nerves of the neck. Superiorly it is attached to the tubercle on the interior arch of the atlas; inferiorly to the anterior surface of the bodies of the three first dorsal and four last cervical vertebrae, to the interver- tebral fibro-cartilages, and to the anterior border of the transverse processes of the third, fourth, and fifth cervical vertebrae. The anterior surface is covered by the rectus capitis anticus major, the pharynx, the carotid artery, the pneumo- gastric and great sympathetic nerves, and the esophagus. The posterior surface covers the vertebrae and their fibro- cartilages to which it is attached: on a level with the two first dorsal vertebrae, its external border is separated from the anterior scalenus by a triangular space lodging the vertebral artery and vein. The office of this muscle is to support the neck, to bend it forwards and to one side. LATERAL CERVICAL REGION. SCALENUS ANTICUS. This muscle, c, is situated at the inferior and lateral part of the neck. It is elongated and divided above into seve- ral portions; superiorly it is attached by tendons to the anterior tubercle of the transverse processes of the third, fourth, fifth, and sixth cervical vertebrae; inferiorly to the superior border of h, the first rib. vol. i. 26 194 MUSCULAR SYSTEM On the anterior surface -of this muscle we find the sub- clavian vein, transverse and ascending cervical arteries, the diaphragmatic nerve, the omo-hyoideus and the sterno- cleido-mastoideus muscles. The posterior surface forms with the following muscle a triangular space/ in which are lodged the subclavian artery and those cervical nerves which form the brachial plexus. The inner side is sepa- rated from the longus colli by the vertebral artery and veins. This muscle bends the head and neck laterally, and raises the first rib. SCALENUS POSTICUS. This muscle, d, is placed behind the preceding ; supe- riorly it is attached to the posterior tubercle of the trans- verse processes of the six last cervical vertebrae, by six small tendons ; inferiorly to the surface of the first rib, and to the superior border of the second rib. The anterior surface of this muscle is connected with the preceding muscle, from which it is separated by the subclavian artery and the anterior branches of the cervical nerves; the posterior surface is connected with the trans- versus cervicis, splenius, and levator scapulae muscles ; on the inner side with the first dorsal and summit of the six lower transverse cervical processes. The anterior and posterior scaleni muscles bend the neck to one side; but when the muscles of both sides act they incline the neck forwards ; or when the neck is fixed, they have the power of raising the ribs and expanding the chest. OF THE TRUNK. 190 RECTUS CAPITIS LATERALIS. This is a short, flat, and thin muscle, f extending from the occipital bone to the transverse process of the atlas. It is connected anteriorly with the jugular vein; poste- riorly with the vertebral artery. This muscle bends the head sideways. CHAP. IV. MUSCLES OF THE TRUNK. ANTERIOR THORACIC REGION, PECTORALIS MAJOR. Fig. 123. This muscle is very large ; its triangular form and the direction of its fibres are marked in the figure at a, b, c. 1st, it is attached to the inner half of a, the clavicle; 2nd, 196 MUSCULAR SYSTEM to the middle part of c, c, the whole length of the sternum; 3rd, at b, to the cartilages of the true ribs, excepting the first, and a little to the bony portion of the fifth rib; and lastly, from an aponeurosis common to it with the abdo- minal muscles. The fleshy fibres run obliquely across the breast, and converging form a small tendon which is fixed to the outer border of the bicipital groove of the os humeri. This tendon is shown in the Fig. 124, broad and folded upon itself, and is thus composed of two laminae, which, with the insertion into the humerus on the inner side of g, the long tendon of the biceps, is very apparent. The anterior surface of the pectoralis major is covered by the platysma myoides, see Fig. 119, by the mammary gland, and common integuments. The posterior surface is situated on the sternum, the cartilages of the ribs, a part of their osseous portions, the thoracic vessels and nerves, the subclavius, pectoralis minor, external intercostal, ser- ratus magnus, rectus, and obliquus abdominis muscles the axilla it is connected with the axillary ganglia, the axillary vessels, the nerves of the brachial plexus, and a considerable quantity of cellular tissue. The pectoralis major is a most powerful muscle in mov- ing the arm; it carries the arm inwards and forwards, and when raised it lowers it, as in striking a blow. When the humerus is fixed it acts upon the thorax, and becomes a muscle of inspiration ; or it can raise the trunk upon the limbs, when holding by the hands in climbing a tree, etc. OF THE TRUNK. 197 PECTORALIS MINOR. Fig. 124. This muscle, a, b, c, d, is situated behind the preceding muscle ; its shape and the direction of its fibres are obvious in the figure. Superiorly it. is attached by a strong flat tendon to d, the coracoid process of the scapula; inferiorly by three divisions at a, b, c, to the third, fourth, and fifth ribs. The anterior surface is covered by the preceding mus- cle ; between them we find some of the thoracic vessels and nerves. The posterior surface is connected with the ribs, the external intercostals, the serratus magnus, the axillary vessels, and the brachial plexus of nerves. The pectoralis minor draws the shoulder bone forwards and downwards, and when that bone is fixed it elevates the ribs. 198 MUSCULAR SYSTEM SUBCLAVIUS. Fig. 125, a. This muscle is placed obliquely under the clavicle. It is attached by its external extremity to the inferior surface of b, the clavicle ; by its internal extremity it is fixed by a flat tendon at c, to the cartilage of the first rib.v The anterior surface of the subclavius is covered by the pectoralis major; between them we observe a thin aponeurosis extending from the clavicle and coracoid pro- cess of the scapula towards the first rib. The posterior surface is placed upon the axillary vessels and the nerves of the brachial plexus; indeed, these separate it from the first rib. This muscle brings forward and downward the clavicle, and consequently the shoulder. v d, the sternum. OF THE TRUNK. 199 LATERAL THORACIC REGION. SERRATUS MAGNUS. Fig. 12G. The serratus magnus is situated on the side of the chest. The form of this muscle and the direction'of its fibres are represented in the figure ; but as part of it lies between the blade bone and the ribs, the collar bone is here divided at d, e, and the blade bone thrown back from the trunk. The serratus magnus is anteriorly attached to eight or nine of the first ribs, a, a, a, a, a, a, a, a, by as 200 MUSCULAR SYSTEM many digitations; posteriorly to b, b, b, the whole length of the base of the scapulaw. The outer surface of this muscle is covered by the tvyo pectoral muscles, the latissimus dorsi, and subscapularis, the axillary vessels, and the brachial plexus; the inner surface is placed over seven or eight of the first ribs, the corresponding external intercostal muscles, and a portion of the serratus posticus. The office of this muscle is to bring the scapula forward ; when that bone is fixed, it becomes a muscle of inspiration: the obliquity of its fibres contributes to raise the ribs. INTERCOSTAL REGION. Fig. 127. w /, the inferior portion of the levator scapulae, g, the inferior portion of the scalenus anticus, b, b, 6, c, the subscapularis. OF THE TRUNK. 201 INTERCOSTALES EXTERNI. Fig. 127. These muscles are the external layers of fleshy fibres which fill up the space between the ribs, a specimen of which is marked a. They are attached on one part to the inferior border of the rib ; on the other, to the superior border of the rib beneath ; the fibres are oblique from above downwards and from behind forwards. The outer surface of these muscles is covered by the pectoral muscles, serratus magnus, obliquus externus ab- dominis, serratus posticus superior and inferior, and sacro- lumbalis. The inner surface is in contact with the pleura, from the tuberosity as far as the angle of the ribs; in the rest of their extent they are in contact with the internal in- tercostal muscles. INTERCOSTALES INTERNI. These muscles, a specimen of which is marked b, are similar in number and in situation to the preceding. They extend from the inferior margin of one rib to the superior margin of the rib below, and from the spine to the breast bone. They differ only in having the fibres pass obliquely from above downwards and from before backwards. The outer surface of this set of muscles is covered by the preceding muscles, and is in contact with the inter- costal vessels and nerves. The inner surface is lined by the pleura. The intercostal muscles are two sets of muscular fibres, the one external, a, the other internal, b, passing in contrary directions, as the old anatomists describe them like St. vol. i. 27 202 MUSCULAR SYSTEM Andrew's cross; excepting that between the cartilages of the ribs, see Fig. 126, there is merely the internal layer, and at a small space from the spine the external layer only. The offices of both the external and internal intercostals are the same; they elevate or depress the ribs, in the motions of inspiration or expiration, according as the upper or lower attachment is the line from which they act. LEVATORES COSTARUM. Fig. 128. These are twelve very small thin tri- angular muscles on either side of the dorsal vertebrae ; they appear as if they a were portions of the external intercos- tals. Each muscle is attached supe- riorly to the transverse process of the lowest cervical and the eleven upper- most dorsal vertebrae; inferiorly to a part of the upper border of the rib next below*. Three or four of the infe- rior elevators, however, are longer than the others, and run down over one rib, to be attached to the alternate rib ; hence Albinus denominated this set of muscles levatores costarum breviores et longiores. The action of these muscles assists in raising the ribs and in supporting the spinal column. A specimen of these muscles is given in the figure b, the transverse process, a, the rib. The whole are represented in Fig. 143, b, b, b, b, b, b, b. OF THE TRUNK. 203 TRIANGULARIS sterni. Fig. 129. This muscle is situated within the thorax, behind the cartilages of the ribs. It is attached on the outer side at a, b, c, d, by four triangular tendinous and fleshy portions, to the cartilages of the third, fourth, fifth, and sixth ribs; on the inner side to the posterior and inferior part of e, the sternum, and at f, to the ensiform cartilage. We have here a posterior view of the triangularis sterni, and this surface is covered by the pleura, and a small part by the diaphragm. The anterior surface is covered by the cartilages of the ribs, the inner intercostal muscles, and internal mammary vessels. 204 MUSCULAR SYSTEM This muscle depresses the cartilages and lowers the extremities of the ribs, and is consequently subservient to expiration. REGION OF THE DIAPHRAGM. This is a broad, thin muscle, dividing the cavity of the chest from the abdomen. Its form is nearly circular, it is OF THE TRUNK. 205 fleshy at its circumference, aponeurotic in the middle. The direction of its radiated fibres is represented in this figure. Anteriorly it is attached at o, to the ensiform cartilage; laterally to the internal surface of the cartilages of the six last ribs; posteriorly to the transverse processes of the first lumbar vertebra ; by its left pillar at &, to the bodies of the three first vertebrae of the same region ; by its right pillar at d, to the bodies of the four first. The structure of the diaphragm consists in part of a three-lobed aponeurosis, b, b, termed the phrenic centre, having an opening for the vena cava, I; it is fleshy at a, a, a, in the rest of its extent, and presenting posteriorly two openings, one at m, for the esophagus and pneumo-gastric nerves, the other traversed by n, the aorta; the vena azygos and throracic duct also pass through it. The tipper surface of the diaphragm is connected with the pericardium, the mediastinum, and the pleura; it supports the heart and the base of the lungs. The lower surface posteriorly is in contact with the kidneys, the surrenal capsules, the pancreas, and the duodenum, on the right side with the liver; on the left side with the spleen and stomach; in its whole extent it is covered by the peritoneum. The diaphragm performs a most important office in the phenomena of respiration ; every time we draw in our breath it contracts, and changing its vaulted form to that of a plane, it enlarges the capacity of the chest so as to admit of the dilatation of the lungs; it may therefore be called the principal muscle of inspiration. On the other hand, when it relaxes, the abdominal muscles press their y Termed also tendinous feet, or crura, c, d, e, f. These feet or crura run obliquely upwards and forwards into two fleshy portions called alae, which mixing and crossing fibres terminate in b, b, the tendinous centre. 206 MUSCULAR SYSTEM viscera upwards, and the diaphragm ascends in the thorax and compresses the lungs, and thus contributes to expi- ration. It also acts in coughing, vomiting, laughing, and speaking, and assists in various other functions, as in the expulsion of the contents of the uterus, bladder, and in- testines. The motion of the diaphragm is moreover subservient to snuffing odours, to sighing, yawning, coughing, sneezing, hiccup, and all those actions connected with inspiration and expiration. OF THE TRUNK. 207 MUSCLES OF THE ABDOMEN. ABDOMINAL REGION. 0BLIQ.UUS ABDOMINIS EXTERNUS. Fig. 131. This muscle is situated on the anterior and lateral parts 208 MUSCULAR SYSTEM of the abdomen; its figure is broad, thin, and irregularly quadrilateral. It is attached superiorly by fleshy triangular slips, called digitations, to the external surface and inferior margin of the seven or eight last ribs ; inferiorly to the two anterior thirds.of the edge of the hip bone. The muscular fibres, i, are directed obliquely from above downwards and from behind forwards, and about the middle terminate abruptly at b, b, the semicircular line (linea semicircu- laris), which runs from the pubis to the ribs. A flat tendi- nous expansion or aponeurosis is then continued to meet with that on the opposite side, where it forms a central tendinous cord, a, a, termed the white line (linea alba), which extends from the ensiform cartilage to the pubis. This line appears to be the result of the reunion of the aponeurosis of the two oblique and transverse muscles upon the median line of the abdomen ; and it is composed of in- extricable fibres of a very strong texture, forming a kind of ligament to unite the sternum to the pelvis. There are lines of a similar nature, passing from the linea semicircularis to the linea alba, marked with the letters c, c, and termed linea transversales. The letter d, marks the umbilicus or navel, consisting of condensed cellular membrane : in the foetus it was a foramen which gave passage to the nutrient vessels, which connected the foetus with the placenta. Inferior]}" the external oblique muscle is fixed to the Fallopian ligament, which appears like a strong resistent 'fold, stretched from the anterior superior spine of the ilium to the pubis. Near this insertion there is a small oblique opening at e, formed as it were by the splitting of the aponeurosis; it is named the abdominal ring: it allows the spermatic cord in the male, and the round ligament of the uterus in the female, to pass through it. The fibres being again united, cross each other, and are inserted into the pubes. This opening is likewise strengthened by tendinous fibres, OF THE TRUNK. 209 which pass transversely, and in various directions, forming it into an elliptical aperture". The outer surface of this muscle is covered by the common integuments, and at the back part by the latissi- mus dorsi; the inner surface is placed on the anterior part of the last eight ribs and their cartilages, the cor- responding intercostal muscles, and the oblique internus. OBLIQJJUS ABDOMINIS INTERNUS. This muscle, Fig. 131, /, is placed behind the pre ceding, and like it is broad, thin, and somewhat quadrila- teral. It is attached superiorly to the border of the car- tilages of the eighth, ninth, tenth, and eleventh ribs; inferiorly, to the spine of the ilium, to the crural arch, and to the pubis ; posteriorly, to the spinous processes of the lumbar vertebrae, and to the sacrum ; anteriorly, to the linea alba. The figure expresses by its lines the direction of the fibres ; viz. the superior fibres are oblique from below upwards, and from behind forwards ; the middle, horizontal; the inferior, a little oblique from above down- wards. The muscle becomes aponeurotic at the linea semicirculdfris, and adheres firmly to it, then divides into two layers. The anterior layer unites with the tendon of the external oblique, the internal adheres to the muscle behind it; they inclose a long muscle, k, k, and are finally reunited at a, a, the central linea alba. The anterior ten- don is here removed to show the rectus muscle. The outer surface is covered by the preceding muscle and by the latissimus dorsi; the inner surface is in con- tact with the transversalis abdominis and sacro-lumbalis. VOL. I. 28 210 MUSCULAR SYSTEM TRANSVERSALIS ABDOMINIS. This muscle is situated behind the oblique muscles; its form is similar, and is attached superiorly to d, the carti- lages of the seven lower ribs; inferiorly, to the crest of b, the ilium, and at c, to the two internal thirds of the crural arch; posteriorly, to the summit of the transverse and OF THE TRUNK. 211 spinous processes of the four first lumbar vertebras. The fleshy fibres proceed transversely, and end in e, a flat sheet of tendon or aponeurosis, which, after being con- nected to the tendons of the two oblique muscles at the semicircular line, it then divides into two laminae to form a sheath for the rectus abdominis; the anterior lamina is united with the aponeurosis of the external oblique muscle, and is extended over the front of the rectus; the posterior lamina is united with the aponeurosis of the internal ob- lique, and is extended behind the rectus, excepting at its lower part; for at the middle distance between the umbi- licus and pubes, a slit or fissure is formed at h, in the aponeurosis of the transversalis, through which the rectus passes, so that the remainder of the aponeurosis passes before the rectus, and is anteriorly inserted into /, the ensiform cartilage, and g, the linea alba. The external surface of this muscle is covered by the obliquus internus, the internal by the peritoneum. RECTUS ABDOMINIS. This muscle, Fig. 131, k, k, Fig. 132, i, is situated immediately in front of the abdomen, on each side of the linea alba, under the anterior laminae of the tendons of the oblique muscles. The rectus abdominis is long and flat, and is attached superiorly to the cartilages of the fifth, sixth, and seventh ribs, and to the ensiform cartilage ; infe- riorly to the pubes. It is divided by three or four tendi- nous intersections, marked in Fig. 131, e, e, denominated the transverse lines; by these divisions the muscle is con- nected firmly to the anterior part of the sheath, while it adheres very slightly by loose cellular substance to the posterior layer. The anterior surface of this muscle is covered by the 212 MUSCULAR SYSTEM aponeurosis of the pectoralis major, and by a lamina of the abdominal aponeurosis, except at the lower part, where we commonly find the pyramidalis. The posterior surface is extended over the cartilages of the three last true ribs, a portion of the cartilages of the last two false ribs, the ensiform cartilage, the posterior fold of the abdominal aponeurosis, the internal mammary and the epigastric ar- teries, and the peritoneum. The office of the last-mentioned muscles, viz. the ex- ternal and internal oblique, the transversalis, and rectus, is to draw down the ribs in expiration: to bend the body obliquely, or to one side when one set acts singly, but when they act together they bend the thorax directly for- wards. They have the power, when the ribs are fixed, of raising the pelvis; they also compress the abdominal vis- cera, so as to raise the diaphragm and expel the air from the lungs ; lastly, they assist in the expulsion of the foetus, urine, and foeces. PYRAMID ALTS. This is a very small muscle, Fig. 131, h, placed over the pubes. It is attached superiorly, near half-way be- tween the pubes and umbilicus, to the linea alba; inferiorly to the pubes. It is connected anteriorly with the abdominal aponeu- rosis ; posteriorly with the rectus abdominis. This muscle merely assists the recti muscles. OF THE TRUNK. 213 LUMBAR REGION, PSOAS MAGNUS. Fis 133. This muscle, g, g, is situated on the side and lower 214 MUSCULAR SYSTEM part of the vertebral column. It is attached superiorly, at e, to the last vertebra of the back, and at h, i, k, I, to the four superior vertebrae of the loins; inferiorly, at m, to the smaller trochanter of the os femoris. The anterior surface of the psoas magnus is connected with the diaphragm, peritoneum, kidney, psoas parvus, external iliac artery, crural artery and vein ; the inner side with the bodies of the lumbar vertebrae and the fibro-carti- lages which separate them, and with the external iliac vein and the pectineus ; the posterior surface with the quadra- tus lumborum, lumbar nerves, and the anterior lamina of the aponeurosis of the transversalis abdominis. Lower down it is connected with the os ilii and the capsular liga- ment of the hip joint. This muscle is a flexor of the thigh on the pelvis, bend- ing the thigh forwards, and rolling it outwards; or, if the inferior extremities are fixed, it will assist in bending the body. PSOAS PARVUS. This muscle, d, does not exist in every subject: it is small and thin, and placed before the preceding muscle. It is attached superiorly, at e, to the last dorsal vertebra and fibro-cartilage, which separates it from h, the first lum- bar vertebra; inferiorly, at /, to the brim of the pelvis7. The anterior surface of the psoas parvus has the dia- phragm, renal vessels and nerves, the peritoneum, and the external iliac artery, extending over it; the posterior sur- face is united in its whole extent by cellular tissue to the psoas magnus. The contraction of this muscle will assist the great psoas muscle in bending the body forwards on the pelvis. « This edge is also named the linea ilio-pectinea. OF THE TRUNK. 215 ILIACUS INTERNUS. This muscle, o, is placed in the cavity of the ilium, from which it is named ; it is large, thick, and radiated. It is attached superiorly, at^?, to the two anterior thirds of the crest of the ilium, and to the principal part of the concave surface of that bone ; its converging fibres join g, the psoas magnus, and are inserted inferiorly with it by one common tendon into (m) the small trochanter of the thigh bone. The anterior surface of this muscle is covered above by the peritoneum on the right, and by the coecum; on the left, by the sigmoid flexure of the colon ; more inferiorly, that is, below the crural arch, by the sartorius, the pec- tineus, and by the crural vessels and nerves. The pos- terior surface is extended over the iliac fossa, the superior part of the rectus femoris, and the hip joint. This muscle powerfully assists in bending the thigh on the pelvis, or the latter on the thigh ; it acts strongly in progression, and in maintaining the body in the erect position. OJJADRATUS LUMBORUM. The name of this muscle, a, a, is expressive of its figure and situation. It is attached superiorly, at b, to the last rib; inferiorly, at c, to the posterior part of the crest of the ilium, and to the ilio-lumbar ligament; and on the inner side, by tendons, to the transverse processes of the four first lumbar vertebrae. This muscle has the power of inclining the body to one side ; if both muscles act, they are flexors of the chest upon the hips, and reciprocally the pelvis upon the trunk. 216 MUSCULAR SYSTEM ANAL REGION. LEVATOR ANI. Fig. 135. 0 p q This muscle, k, with its fellow, is a sort of concave floor to the abdominal and pelvic cavity, or it may be compared to a shallow funnel surrounding the extremity of the in- testine. It is very thin, and is attached superiorly to the inner part of the pubes, to the superior part of the obtu- rator foramen, and to the spine of the ischium ; inferiorly, the middle and anterior fibres unite beneath the rectum enveloping this intestine; the most anterior seem attached to the prostate gland; other fibres spread forwards on the commencement of the urethra, and backwards to n, the os coccygis, forming a tendinous line. OF THE TRUNK. 217 The outer surface of this muscle is connected by a layer of cellular tissue to the gluteus maximus, the obturator internus, and transversus perinaei. The inner surface is connected with the bladder, prostate gland, and lowTer part of the rectum. The use of this muscle, as its name implies, is to draw up the rectum after its contents have been expelled. COCCYGEUS. This is a thin, flat, triangular muscle, f attached on the one part to g, the spinous process of the ischium; its fibres diverge, and are inserted on the other part into n, the border of the os coccygis, and into h, the extremity of the sacrum. The posterior surface of this muscle, which inclines downwards, is covered by the sacro-sciatic ligaments; the anterior is connected to the rectum by cellular tissue. This muscle moves the coccyx, and secures this bone in its situation. SPHINCTER ANI. This muscle, e, is of an oval figure, open in its centre; its fibres surrounding the extremity of the rectum or anus are accurately expressed in the figure. It is attached, at n, to the os coccygis, by a species of cellular tendon, from whence two fleshy fasciculi proceed, uniting together in front of the anus. The upper surface is connected with the levator ani by a cellular tissue ; the lower surface is covered by the com- mon integuments. This muscle closes the anus, and in the male draws down the bulb of the urethra. vol. i. 29 218 MUSCULAR SYSTEM GENITAL RE GIO N. I. IN THE MALE. CREMASTER. This muscle consists of a few scattered fibres, sent off by the obliquus internus abdominis, over the spermatic cord, and expanded upon the tunica vaginalis testis. For a view of this muscle we must refer back to Fig. 131, g. This muscle draws up the testis. ISCHIO-CAVERNOSUS. This is a small elongated muscle, c, placed along the ramus of the ischium, and root of o, the corpus caverno- sum. It is attached on the one part to the tuber ischii, and on the other part to the fibrous membrane of the cor- pus cavernosum. The outer surface corresponds with the ramus of the ischium ; the inner is connected with the transversus peri- naei and bulbo-cavernosus. This muscle draws the root of the penis downwards and backwards. BULBO-CAVERNOSUS. This muscle, d, is situated beneath the bulb of the ure- thra, and covering part of p, the corpus spongiosum. It is attached to these parts, and its fibres are confounded with the muscles of the anal region; but it is separated from its fellow muscle by a tendinous line. OF THE TRUNK. 219 The superior surface covers the bulb and commence- ment of the spongy portion of the urethra and corpus ca- vernosum; the inferior surface is connected with the pre- ceding muscle and common integuments. This muscle compresses the posterior part of the ure- thra, and urges forward any fluid which that canal may contain; hence it has been sometimes denominated acce- lerator urinae, vel ejaculator seminis. TRANSVERSUS PERINEIa. This is a flat and thin muscle, /; the name indicates its situation. It is attached on its outer part to the ramus and tuberosity of the ischium; on the inner part to the middle line, with its fellow on the opposite side. The exterior surface is covered by the common integu- ments ; its other relations may be seen in the figure. This muscle is supposed to dilate the urethra ; it cer-> tainly supports the lower part of the bladder and rectum. There is frequently another slip of muscular fibres, tak- ing the same course, termed transversus perinei alter. II. IN THE FEMALE. ISCHIO-CAVERNOSUS. This muscle is similar to that just described in the other sex, but is much smaller. It is attached on the outer side to the tuber ischii; on the inner it terminates by embracing the cavernous body of the clitoris. * The perineum is that space which is between the genitals and anus. 220 MUSCULAR SYSTEM CONSTRICTOR VAGINA. Fig. 136. This muscle, a, consists of a number of muscular fibres, forming a sort of broad fleshy ring surrounding the vaginab. This muscle contracts the part which it embraces. b i, the pubis, e, the bladder, d, the uterus, e, the rectum, OF THE TRUNK. 221 MUSCLES OF THE POSTERIOR PART OF THE TRUNK. k 222 MUSCULAR SYSTEM The trapezius is a broad, flat muscle, a, b, d, and Fig. 138, a, e, d, situated at the posterior part of the neck, shoulder, and upper part of the back. It is attached supe- riorly, at a, the superior transverse line of the occipital bone, to the cervical ligament, and to the spinous pro- cesses of the seventh cervical vertebrae; inferiorly to the spinous processes of all the dorsal vertebrae; on the outer side to d, the spine of the scapula, and the edge of this muscle slides over e, a triangular space at the extremity of that bone, to the acromion, and to c, the external third of the clavicle. The direction of the fibres is shown by the lines of the engraving. The posterior surface of the trapezius is entirely covered by the common integuments; the anterior surface is con- nected at its upper and inner part with the complexus major; further down with the splenitis, levator anguli sca- pulae, and serratus posticus superior: at its lower part it covers the supra-spinatus, infm-spinatus, rhomboideus, la- tissimus dorsi, and sacro-lumbalis muscles. When all the fibres of this muscle act simultaneously, they draw back the scapula and clavicle ; the upper fibres will elevate the tip of the shoulder, the lower will move it backwards and obliquely downwards. If the shoulder is fixed, the trapezius has the power of inclining the head to one side. LATISSIMUS DORSI. This is a large, thin, flat muscle, placed on the back and side of the lower part of the trunk. It is attached supe- riorly, at /, to the inner edge of the groove in the os humeri, which receives the long tendon of the biceps; inferiorly, to the posterior half of g, the external border of the crest of the ilium, and at /, to the back and upper part of the sacrum ; on the inner side it is fixed to the spi- OF THE TRUNK. 223 nous processes (from b to I) of all the lumbar vertebrae, and to those of the six or seven lower dorsal; on the outer side to the four last ribs, at n, n, n, n, by as many digi- tations. The direction of the fibres is expressed in the figure; they are aponeurotic at the internal and inferior part of the muscle, tendinous at its insertion into the hu- merus, and fleshy in other parts. The superior edge passes over the inferior angle of the scapula at m, and sometimes has a slip attached to it, and the margin at f forms the fold of the back part of the arm-pit. This muscle is also represented in Fig. 138, at b. The posterior surface of this muscle is covered by the integuments, excepting at its upper and inner part, which is covered by a, d, b, the trapezius. The anterior sur- face is connected with the obliquus abdominis, serratus posticus inferior, sacro-lumbalis, levatores costarum, exter- nal intercostal muscles, the serratus magnus, rhomboideus, teres major, infra-spinatus, the lower ribs, and the inferior angle of the scapula. The office of the latissimus dorsi is to carry the arm backwards and downwards; or, when the hand is fixed, it brings forward the body. 224 MUSCULAR SYSTEM ORSO-CERVICAL REGION, RIIOMBOIDEUS. Fisr. i:i-;. The situation and form of this muscle, i, f is clearly OF THE TRUNK. 225 exhibited in the figure. It is attached by its internal mar- gin to the posterior cervical ligament, to the spinous pro- cess of the seventh cervical vertebra, and to those of the four or five first dorsal; by its internal margin, at n, to all the base of the scapula below o, the spine of that bone. This muscle is divided by a cellular line into two portions : therefore frequently denominated, f, the rhomboideus ma- jor, i, the rhomboideus minor. The posterior surface of the rhomboideus is covered by the trapezius and latissimus dorsi; the anterior surface covers the serratus posticus superior, the splenius, the sa- cro-lumbalis, the ribs, and external intercostal muscles. The action of this muscle is to bring the scapula ob- liquely upwards and directly backwards. vol. i. 30 226 MUSCULAR SYSTEM LEVATOR SCAPULiE. Fig. 139. This is a long, thick muscle, a, placed at the side and back of the neck. It is attached superiorly to the trans- verse processes of four or five of the superior vertebrae of the neck, by distinct tendons ; these unite and form a strong muscle, which is fixed inferiorly into the base of the scapula above c, the spine. See also Fig. 138, h. The outer surface of this muscle is covered on the up- per part by the sterno-cleido-mastoideus, in the middle by OF THE TRUNK. 227 the skin, and below by the trapezius. The inner surface is connected with the serratus posticus superior, the sacro- lumbalis, and splenius. This muscle raises the posterior angle of the scapula, and consequently depresses the tip of the shoulder; it has the power also of inclining the neck to one side, or main- taining it in an erect position when it acts in conjunction with its fellow. SERRATUS POSTICUS SUPERIOR. This muscle, g, is very thin; its situation and form are delineated in the figure. It is attached by its internal border to the posterior cervical ligament, to the spinous process of the last cervical vertebra, and to those of the three upper dorsal; outwardly, by distinct fleshy portions, or digitations, into the second, third, fourth, and sometimes the fifth ribs, a little beyond the angle. The posterior surface is connected with the rhomboi- deus, the levator anguli scapulae, serratus magnus, and trapezius ; the anterior surface with the splenius, longis- simus dorsi, transversalis colli, sacro-lumbalis, ribs, and the external intercostals. The action of this muscle dilates the thorax, by elevat- ing the ribs. SERRATUS POSTICUS INFERIOR. For the form of this muscle, the reader is referred back to the preceding engraving, Fig. 138, I. It is situated at the inferior part of the back, and, like the serratus supe- rior, is broad and thin. It is attached by its inner border to the spinous processes of the two lower dorsal vertebrae, and to those of the three upper lumbar; at its outer bor- der, by distinct slips into the four inferior ribs. 228 MUSCULAR SYSTEM The posterior surface is connected with the latissimus dorsi; the anterior surface with the three lower ribs, the corresponding intercostal muscles, and the posterior lamina of the aponeurosis of the transversalis abdominis. This muscle depresses the ribs, and draws them back- wards. SPLENIUS. This muscle, Fig. 138, b, c, d, Fig. 139, k, is placed obliquely at the back of the neck ; its form is elongated and flattened. It is divided by a line of cellular membrane into two portions, which have sometimes been considered as two muscles, and in the last-mentioned figure is attached superiorly, at b, to the mastoid process of the temporal bone, and at c, to the occipital bone immediately below the superior transverse ridge; inferiorly, at d, to the last cervical and six upper dorsal vertebrae. The external surface of the splenius is connected with the sterno-cleido-mastoideus, the trapezius, levator anguli scapulae, serratus posticus superior, and rhomboideus; the internal surface with the great and little complexus. The contraction of this muscle will turn the head, or incline the head and neck completely backwards; when both muscles act together, they bend the head directly backwards. OF THE TRUNK. 229 COMPLEXUS. Fig. 140. The situation and form of this muscle, a, is obvious in the figure before us. It is .attached superiorly, at b, be- tween the transverse ridges of the occipital bone; inferiorly, by isolated fasciculi of tendinous and fleshy fibres, at c, c, c, c, c, c, to the transverse and articular processes of the last six cervical vertebrae, and at e, e, e, e, to the trans- verse processes of the four or five first dorsal vertebrae. These attachments are frequently confounded with those of the transversus colli. The external surface is connected with the trapezius, splenius, and trachelo-mastoideus; the internal with the 230 MUSCULAR SYSTEM semi-spinalis colli, the arteria cervicalis profunda, the pos- terior branches of the cervical nerves, the rectus capitis posticus minor, and the obliquus capitis inferior. This muscle draws the head backwards and to one side. When the two act together, the face is turned upwards. TRACHELOb-MASTOIDEUS. This muscle is much smaller than the preceding, and is placed on its outer edge. It is attached superiorly at a, to the posterior part of the mastoid process of the temporal bone ; inferiorly, at b, to the transverse processes of the four last cervical vertebrae, and sometimes, at c, to the first b So called from a Greek word for the spine. This and the former muscle are as fre- quently denominated complexus major ct minor, and their resemblance may be seen by com- paring the figures before us. OF THE TRUNK. 231 dorsal, by distinct tendinous and fleshy fasciculi. The trachelo-mastoideus is also connected at its inner edge by a fleshy band to the longissimus dorsi. Both this and the preceding muscles are traversed by aponeurotic intersec- tions or bands, varying in direction and position. The outer surface of this muscle is connected with the splenius and transversalis colli; the inner with the com- plexus and obliquus capitis, the posterior extremity of the digastricus, and the occipital artery. The action of this muscle keeps the head erect, or in- clines it a little backwards or to one side, without rotation. POSTERIOR OCCIPITO-CERVICAL REGION. RECTUS CAPITIS POSTICUS MAJOR. Fig. 142. This is a small muscle, a, situated on the upper part of the back of the neck. It is attached superiorly to the lower transverse ridge of the occipital bone, and to part of 232 MUSCULAR SYSTEM the depression above that ridge, between the rectus capitis posticus minor and obliquus capitis superior. Inferiorly it is fixed to the spinous process of the dentata or second cervical vertebra. The posterior surface of this muscle is connected with the complexus and obliquus capitis superior; the anterior surface with the occipital bone, the atlas, the rectus capitis posticus minor, and the vertebral artery. RECTUS CAPITIS POSTICUS MINOR. This is a very small muscle, b, attached superioily to the occipital bone behind the foramen magnum, and a little to the side of the inferior curved line ; inferiorly to the tubercle at the posterior arch of the atlas. The posterior surface of this muscle, which is inclined downwards, is connected with the great complexus and with the preceding muscle ; the anterior surface with the occipital bone, the alloido-occipital ligament, and the ver- tebral artery. OBLIQUUS CAPITIS SUPERIOR. The relative size and situation of the obliquus capitis superior, c, is expressed in the figure ; it is attached supe- riorly to the outer part of the curved line of the occipital bone; inferiorly to the transverse process of the first cer- vical vertebra, in front of b, the preceding muscle. The posterior surface is connected with the complexus, the trachelo-mastoideus, and the splenius; the anterior with the occipital bone, the vertebral artery, and the at- tachment of the rectus capitis posticus major. OF THE TRUNK. 233 OBLIQUUS CAPITIS INFERIOR. This muscle, d, will be found to resemble very much the superior oblique ; it is attached superiorly to the trans- verse process of the atlas, and inferiorly to the spinous process of the dentata. The posterior surface is connected with the complexus and trachelo-mastoideus; the anterior with the second ver- tebra, and with the posterior ligament uniting the axis and atlas, and with the vertebral artery. The office of the four muscles just described, according to their several directions and obliquity, is to rotate the head, incline it backwards or to one side, and to maintain the head in the erect position. INTERSPINALES CERVICIS. There are six very small muscles, at e, e, e, e, e, e, on either side of the intervals of the spinous processes of the neck. Each of them is attached superiorly to the lower surface of the spinous process, and inferiorly to the upper surface of the next spinous process below it. These muscles draw the spinous processes nearer to each other, and consequently incline the head backwards. Similar sets of muscles occupy the spaces between the spinous process of the vertebrae of the back and loins; in the neck, however, they are double, corresponding to the bifurcations of the spinous processes. In the back and loins they are indistinct, and are rather like tendons than muscles. vol. i. 31 234 MUSCULAR SYSTEM VERTEBRAL REGION. LONGISSIMUS DORSI. Fig. 143. The longissimus dorsi, d, d, constitutes part of the thick OF THE TRUNK 235 muscular mass which occupies the space between the spi- nous processes of the vertebrae and the angle of the ribs. On the inner side it is attached by small double tendons to all the transverse processes of the back, and to the last transverse process of the neck; from its outer side it sends off fleshy and tendinous filaments, which are inserted into the eight lower ribs. Inferiorly, it is attached in common with the sacro-lumbalis. The internal surface of the longissimus dorsi is con- nected with the multifidus spinae, complexus, and transver- salis colli; the external is contiguous to the sacro-lumbalis; the anterior is placed upon the levatores costarum, the ribs, the transverse processes of the vertebrae, the posterior costo-transverse ligaments, the dorsal vessels and nerves, and a portion of the external intercostal muscles. The posterior surface is connected with the aponeurosis of the obliquus internus and transversalis abdominis, serratus posticus superior, latissimus dorsi, trapezius, rhomboideus, and splenius. 236 MUSCULAR SYSTEM SACRO-LUMBALIS. Fig. 144. This muscle, a, a, is situated on the outer side of b, the latissimus dorsi, extending from the sacrum to the neck. « OF THE TRUNK. 237 On the right side of the figure we see it is attached on the outer part to the lower edge of all the ribs, by as many distinct tendons ; on the inner part we find it is attached to the upper border of nine or ten of the lower ribs, by as many tendons. The muscle on the left side is drawn back with the hook, f to show these tendons. There are some portions of this muscle marked g, g, which are inserted into the transverse processes of five or six of the lower cervical vertebrae by as many distinct tendons. These fasciculi are frequently described under the name of the cervicalis descendens. The sacro-lumbalis is inferiorly fleshy within and aponeurotic without; and, as I before observed, forms one inseparable muscle with the longis- simus dorsi, which is attached at e to the sacrum, the pos- terior spine of the ilium, all the spinous processes, and near the roots of the transverse processes of the lumbar vertebrae : not separating from b, b, its companion just mentioned, till it reaches the ribs. The anterior surface of the sacro-lumbalis is connected with the aponeurosis of the transversalis abdominis, the ribs, and external intercostal muscles, the longissimus dorsi, and transversalis colli. The inner side with the longis- simus dorsi; the outer side with the line of union of the posterior laminae of the aponeurosis of the transversalis abdominis. The longissimus dorsi and sacro-lumbalis preserve the vertebral column from yielding to the weight placed on it and before it; in a word, they are the most powerful mus- cles that are employed in keeping the body erect. TRANSVERSALIS COLLI. This muscle, Fig. 143, a, lies on the inner side of the longissimus dorsi, and is indeed sometimes considered as an appendage to it. It is attached superiorly, by small 238 MUSCULAR SYSTEM tendons, to the transverse processes of the second, third, fourth, fifth, and sixth cervical vertebrae ; inferiorly it is fixed by tendinous and fleshy slips to the transverse pro- cesses of the third, fourth, fifth, sixth, and seventh dorsal vertebrae. The posterior edge of this muscle is blended with the trachelo-mastoideus muscle : in the middle it is connected with the levator anguli scapulae and the serratus posticus superior, and below with the longissimus dorsi. The ante- rior edge is connected with the transverse processes of the second cervical to the eighth dorsal vertebra. The outer surface corresponds with the splenius, levator anguli sca- pulae, and sacro-lumbalis; the inner with the complex! and part of the multifidus spinae. This muscle turns the neck obliquely backwards and to one side. MULTIFIDUS SPIN.2E. The fasciculi, c, c, composing this mass of muscles, are placed obliquely from the transverse processes to the spi- nous processes. They are attached by distinct tendons to all the spinous, transverse, and articular processes of the six last cervical vertebrae, the twelve dorsal, and the five lumbar, and to the posterior surface of the sacrumc. The posterior surface of these muscles is connected with the trachelo-mastoideus, arteria cervicalis profunda, posterior cervical nerves, and longissimus dorsi; the ante- rior surface with the plates of the vertebrae, their trans- verse and oblique processes, and the ligamenta subflava; on the inner side with the spinous processes of the verte- brae, the interspinalis cervicis, and the dorsal and lumbar interspinous ligaments. c These have been described by some anatomists as three distinct sets of muscles, viz. transverso-spinalis colU, transverso-spinalis dorsi, transverso-spinalis luinborum. OF THE TRUNK. 239 The office of these muscles is to incline the vertebral column to one side; but when the muscular fibres on each side act, they keep the body erect. INTER-TRANSVERSALES COLLI. These are small muscles which fill up the spaces be- tween the transverse processes of the vertebrae of the neck. They are^ distinguished into anterior, six in number on either side, and into posterior, five in number. The two muscles of each interval are separately attached, and ex- tend from the inferior border of the transverse process of the vertebra above, to the superior border of the transverse process of the vertebra below. The anterior set are connected in front with the rectus capitis anticus major; the posterior behind, with the sple- nius, transversalis colli, and sacro-lumbalis. These muscles contribute to the lateral motions of the neck. INTER-TRANSVERSALES LUMBORUM. Between the transverse processes of the lumbar verte- brae are fleshy fasciculi, similar to those just described. There are five on each side; they are stronger and more distinct than the preceding muscle. Their posterior surface is connected with the sacro-lum- balis ; the anterior with the quadratus lumborum. Their lower and upper edges are connected with the correspond- ing adjacent transverse processes by means of short apon- eurotic fibres. These muscles are supposed to bend the lumbar region of the vertebral column laterally; the short muscles of the spine certainly strengthen the back during muscular exer- tions. 240 MUSCULAR SYSTEM CHAP. V. MUSCLES OF THE EXTREMITIES. MUSCLES OF THE SUPERIOR EXTREMITY. MUSCLES OF THE SHOULDER. POSTERIOR SCAPULAR REGION. SUPRA-SPINATUS. Fig. 145. I This muscle, I, fills up the cavity above the spine of the scapula. Its attachment on the inner side is fleshy, from the whole concave surface above k, the spine of the sca- pula, from the spine, and from the superior border of that bone, passing under the acromion and adhering to the cap- sular ligament of the joint; on the outer part it forms a strong tendon, which is inserted into the greater tuberosity of the humerus. OF THE SUPERIOR EXTREMITY. 241 The posterior surface of this muscle is connected with the trapezius, deltoides, and coraco-acromial ligament; the anterior with the fossa supra-spinata, the superior scapular vessels and nerves, and with the capsule of the shoulder joint. This muscle raises the arm, and if the arm is fixed it acts upon the shoulder. INFRA-SPINATUS. The infra-spinatus, a, b, c, d, occupies that space on the back of the scapula which is below the spine. It is at- tached, on the inner side, to the two internal thirds of the infra-spinata fossa; the fibres converge towards a central tendon which runs over the neck of the bone, adheres to the capsular ligament, and is inserted into d, the greater tuberosity of the humerus. The posterior surface of the infra-spinatus is connected with the deltoides, trapezius, latissimus dorsi, and integu- ments ; the anterior surface with the infra-spinata fossa, from which it is separated, in its outer third, by cellular tissue, and by the superior scapular nerve and vessels. It is also applied upon the capsule of the shoulder joint. The lower edge is confounded with e, f, the teres minor. This muscle turns the arm outwards, and assists in rais- ing it. TERES MINOR. This muscle, e, f is placed along the inferior border of the scapula. A strong aponeurosis covers this and the infra-spinatus; indeed, the two muscles in some subjects are so closely united, as to be with difficulty separated. On the inner part, it is attached to the inferior angle of the scapula, and to the third of the inferior border of that vol. i. 32 242 MUSCULAR SYSTEM bone; on the outer part it extends to /, the lower and back part of the tuberosity of the humerus, where it is fixed by a strong tendon. The posterior surface is connected with the deltoides and integuments; the anterior with the external scapular artery, the long portion of the triceps, and the capsule of the articulation of the shoulder. Superiorly, it is con- nected with c, d, the lower edge of the infra-spinatus mus- cle ; inferiorly, with g, h, the teres major, from which at one part it is separated by i, the long portion of the triceps. The office of the teres minor is similar to that of the preceding muscle. TERES MAJOR. This muscle, g, h, is situated beneath the teres minor. On the inner side it is attached to the quadrilateral surface of the inferior border of the infra-spinata fossa, and to the lower third of the base of the scapula. On the outer side it is inserted by a broad tendon into the inner side of the bicipital groove of the humerus. The posterior surface is connected with the latissimus dorsi, the integuments, the humerus, and the long portion of the triceps ; the anterior with the subscapularis, latissi- mus dorsi, coraco-brachialis and biceps, the axillary vessels and brachial plexus of nerves. The lower edge is covered by the integuments, and, with the latissimus dorsi, forms the posterior edge of the axilla. The upper edge is united to the teres minor, from which at one part it is separated by the long portion of the triceps. The teres major turns the arm inwards and draws it backwards. OF THE SUPERIOR EXTREMITY. 243 ANTERIOR SCAPULAR REGION. SUBSCAPULARIS. Fig. 146. This is a very thick triangular muscle, a, occupying the whole of the subscapular fossa. It is attached on the inner side to the internal three fourths of the subscapular fossa; the fibres are disposed in fleshy bundles with aponeurotic septa, which converging slide over the inner surface of the M* 244 MUSCULAR SYSTEM neck of the scapula, and pass under i, the coracoid process; it then forms a broad and flat tendon which adheres to the capsule of the joint, and is finally fixed at c, to the small tuberosity of the humerus. The anterior surface of the subscapularis is. connected by a thick layer of cellular tissue with the serratus magnus, the brachial plexus of nerves, the axillary artery, and the coraco-brachialis, the biceps and the deltoid muscles; the posterior surface with the subscapular fossa, and with the teres major, the long portion of the triceps extensor cubiti, and with the capsule of the articulation of the shoulder. When the arm is distant from the body it draws it near; or it turns the arm inwards ; or when raised it depresses it. EXTERNAL SCAPULAR REGION. I)ELTOIDESd. Fig. 132. <1 So named from its resemblance to the Greek letter &. OF THE SUPERIOR EXTREMITY. 245 The deltoides forms the fleshy part of the shoulder; its shape and the direction of its fibres are exhibited in the figure. Superiorly it is attached by aponeurotic fibres at a, to the external third of the clavicle; at b, to the acromion process; and at c, to the lower margin of the spine of the scapula; inferiorly the fibres concentrate to a tendon which is inserted at d, into the deltoid impression in the middle part of the external surface of the humerus. This muscle is composed of large fasciculi of fibres separated by grooves more or less deep. The inner surface is aponeurotic; and where it lies over the greater tuberosity of the qs humeri, there is a bursa of considerable size. The external surface of the deltoides is connected with the platysma myoides, the integuments; the internal with the infra-spinatus, teres minor, and triceps extensor mus- cles, the tendon of the supra-spinatus, the acromio-coracoid ligament, the subscapularis, pectoralis minor, biceps and coraco-brachialis muscles, the coracoid process, the cap- sule of the articulation, the superior third of the external surface of the humerus, and tendon of the pectoralis major. The anterior part, which is parallel to the external border of the biceps, is separated from the pectoralis major by the cephalic vein. The principal office of this muscle is to raise the arm; but it is also capable of moving it forwards or backwards, according as the anterior or posterior fibres are brought into action. 246 MUSCULAR SYSTEM ' CORACO-BRACHIALIS. Fig. 148. OF THE UPPER EXTREMITY. 247 We see the situation of this muscle, a, in the figure; it is long, flat, and narrow. It is attached by a tendon at a, to the apex of b, the coracoid process of the scapula; it terminates tendinous about c, the middle of the humerus, and is inserted into a rough elevated line. The anterior surface is connected with the deltoides, pectoralis major, and biceps; the posterior with the sub- scapularis muscle, the united tendons of the latissimus dorsi and teres major, the axillary artery, the musculo- cutaneous and median nerves, and the brachial artery. This muscle moves the arm forwards, upwards, and in- wards. The coraco-brachialis is perforated by a nerve called musculo-cutaneous. The intermuscular aponeurosis is seen extending from the lower part of this muscle along a ridge to the internal condyle, separating the brachialis internus from the third head of the triceps. BICEPS FLEXOR CUBITI. This muscle, Fig. 146, k, is situated at the front and inner part of the arm; it is thick at its middle portion, thin at its extremities, the superior of which is divided into two portions. Its short portion is attached at h, to the cora- coid process of the scapula, along with m, the preceding muscle, and by g, its long portion, to the superior part of the glenoid cavity; at k, the two portions or heads form a hick mass, and about the middle of the arm become inse- parably united ; it is finally inserted at its inferior extremity to the tubercle at the upper end of the radius, and by a tendinous expansion into the aponeurosis of the fore-arm. The anterior surface of this muscle is connected with the deltoid and great pectoral muscles, the brachial apon- eurosis, and the integuments ; the posterior with the hu- merus, a, e, the coraco-brachialis, h, the brachialis internus, 248 MUSCULAR SYSTEM and the musculo-cutaneous nerve ; on the inner side with the coraco-brachialis above, and in the middle and befow with the brachial artery. The biceps flexor cubiti bends the fore-arm on the arm, and the arm on the shoulder. BRACHIALIS INTERNUS. This muscle, d, e, is situated at the anterior and inferior part of the arm. At its upper extremity, d, it is attached on each side of the insertion of the deltoides, to the ex- ternal and internal surface of c, the humerus, and to most of the lower and fore part of the bone, as far as the articu- lation of the elbow joint; it has also an attachment to the external and internal aponeurosis, and inferiorly, by a strong tendon at e, to the rough surface immediately below the coronoid process of the ulna. The fibres pass over the joint, and adhere to the capsular ligament. The anterior surface of this muscle is connected with the brachial aponeurosis and the integuments, the supinator radii longus, the biceps, the musculo-cutaneous nerve, the brachial artery, the median nerve, and the pronator teres; the posterior surface with the inferior part of the humerus, and the articulation of the elbow. The brachialis internus bends the fore-arm. TRICEPS EXTENSOR CUBITI. The triceps, f g, h, i, occupies all the posterior part of the arm. It is very thick and fleshy, and is divided at the upper part into three portions, from whence it derives its name. Of these, the first or middle, which is longer and larger than the others, is attached by a broad tendon, /, to the inferior border of the scapula, near its neck; it then forms a large fleshy mass, which covers the back of the OF THE UPPER EXTREMITY. 249 os humeri. The second, or outer portion, g, is attached by a pointed extremity to the outer and back part of the os humeri, below the great tuberosity, and to a ridge which runs from that eminence to the outer condyle, and to the intermuscular aponeurosis, which is common to it and the brachialis internus. The third or inner portion, h, which is the shortest, commences by an acute form from the inner edge of the os humeri near its middle, and receives an addition of fibres from the intermuscular partition; its fleshy fasciculi descend backwards and outwards. The three portions of this muscle unite about the middle of the humerus, invest the whole back part of the bone, and ter- minate by a very strong, broad, and thick tendon, which is inserted into the upper part of the olecranon. The posterior surface of the triceps extensor is con- nected above with the deltoides and teres minor, the bra- chial aponeurosis and integuments. The anterior surface is connected with the subscapularis, teres major, and latis- simus dorsi, the capsule of the articulation of the shoulder, and the posterior part of the elbow joint. The triceps extensor, by extending the fore-arm, acts in opposition to the biceps flexor. The long portion has the power of carrying the arm backwards. VOL. I. 33 250 MUSCULAR SYSTEM MUSCLES OF THE FORE-ARM. ANTERIOR REGION OF THE FORE-ARM. PRONATOR TERES. This muscle, a, is extended obliquely across the upper and anterior part of the fore-arm. See also Fig. 150, a, b, c, and Fig. 153, a, b. Superiorly it is attached to the anterior part of the inner condyle of the humerus, and to the inner side of the coronoid process of the ulna; between these two parts the median nerve passes. Inferiorly it is fixed to the middle part of the external surface of the radius. The anterior surface of this muscle is connected with the apo- neurosis of the fore-arm and inte- guments, the supinator radii longus, the radial vessels and nerves, and the external radial muscles; the posterior surface with the brachi- alis internus, the flexor sublimis, the median nerve, and the ulnar artery; on the inner side with the triangular space for the tendon of the biceps, the brachial artery, the median nerve, and the supina- tor radii brevis. The pronator teres turns the radius and hand inwards, or it may assist as a flexor of the fore-arm. * OF THE UPPER EXTREMITY. 251 FLEXOR CARPI RADIALIS. This muscle, b, is situated on the inner side of the pre- ceding. It has a tendinous attachment to the fore part of the inner condyle of the humerus, fleshy to the fascia and intermuscular aponeurosis, and to the upper end of the ulna. The extent of its muscular fibres is marked in the figure. The tendon of this muscle passes under the an- nular ligament of the wrist, through a groove in the trape- zium, and is fixed to the base of the metacarpal bone which sustains the fore-finger. The anterior surface of the flexor carpi radialis is con- nected externally with a, the supinator longus, and with the aponeurosis of the fore-arm ; the posterior surface with the flexor digitorum perforatus, the flexor longus pol- licis muscles, and the wrist. This muscle bends the wrist, turning it a little inwards. It also serves as a flexor of the fore-arm. PALMARIS LONGUS. This muscle, c, d, is not always to be found in the arm. It has a slender form, and is attached superiorly by tendi- nous fibres to the inner condyle of the os humeri; it then forms, at c, a thin fleshy mass, which about the middle of the arm sends off a small tendon which is inferiorly adhe- rent to the annular ligament, and is spread out into a very strong tendinous membrane, d, named the palmar aponeu- rosis, which is finally fixed to the roots of all the fingers. The anterior surface is connected with the aponeurosis of the fore-arm ; the posterior surface with the superficial flexor of the fingers. The palmaris binds down the muscles of the palm of the hand, and its aponeurosis protects the blood-vessels and nerves in their course to the fingers. 252 MUSCULAR SYSTEM FLEXOR CARPI ULNARIS. The flexor carpi ulnaris, e, is situated internally to the preceding muscles of the fore-arm. It is half-penniform, and is attached by means of a common tendon to the inner side of the olecranon, and to the posterior border of the ulna; a number of its fibres are also united to the apon- eurosis of the fore-arm. Inferiorly it becomes tendinous, and is inserted into the pisiform bone, and some fibres are detached from it to the annular ligament of the wrist. The anterior surface of this muscle is connected with the aponeurosis of the fore-arm; the posterior surface with the deep flexor of the fingers, the ulnar artery and nerve, and the pronator quadratus, and on the outer edge with the flexor sublimis. This muscle bends the wrist, inclining it a little towards the ulna. When it contracts at the same time with the flexor carpi ulnaris, it draws the hand directly upwards. OF THE UPPER EXTREMITY. 263 FLEXOR DIGITORUM SUBLIMIS VEL PERFORATUS. This muscle, d, e, is situated immediately beneath the Fio. 150 preceding muscles. It is attached superiorly at d, to the inner con- dyle of the humerus; at b, to the coronoid process of the ulna ; and at c, to the upper part of the an- terior border of the radius ; these several attachments as they des- cend form a strong fleshy mass, which sends off four tendons ; the tendons are connected by cellular tissue, and pass under the annular ligament of the wrist; from thence diverging as they proceed towards their respective fingers, each ten- don, as it were, splits at the ex- tremity of the first phalanx for the passage of the flexor profundus, and is attached to the second pha- lanx. In this figure the fibrous sheaths of the fingers are pinned open ; and in the fore finger, at g, we observe the splitting of the tendon just mentioned. The anterior surface of this muscle is connected with the pro- nator teres, the flexor carpi radialis, the palmaris longus, the aponeurosis of the fore-arm, the annular ligament, the pal- mar aponeurosis, the fibrous sheaths of the fingers, and with the tendons of the deep flexor. The posterior sur- 254 MUSCULAR SYSTEM face is connected with the flexor profundus, the flexor longus pollicis, the median nerve, the ulnar artery, the lumbricales muscles, and the phalanges. This muscle bends the second joint or phalanx upon the first, and the hand upon the fore-arm. Fig 151. a Tendon of the flexor sublimis. b The division or slit in the tendon for the passage of c. The tendon of the flexor profundus, to be attached at e, the extremity of the finger. OF THE UPPER EXTREMITY. 255 ANTERIOR DEEP REGION OF THE FORE-ARM. Fig. 152. FLEXOR DIGITORUM PROFUNDUS VEL PERFORANS. This muscle is situated beneath the preceding; supe- riorly it is attached, at a, to the three superior fourths of the ante- rior and internal surfaces of the ulna, and at b, to the interosseous ligament; the muscular fibres then form a thick mass upon the fore part of the ulna, and divide into four portions, each of which is ter- minated by a tendon. These ten- dons pass under the annular liga- ment of the wrist, and perforate the slits or fissures in the flexor sublimis, as in Fig. 150, and at length are inserted into the ante- rior part of the third phalanx of the fingers. Fig. 151 best explains the mode in which the tendon of the flexor sublimis, a, divides at b, to transmit the tendon of the flexor profundus, c, e. The anterior surface of the flexor profundus is connected with the flexor sublimis and flexor carpi ulnaris muscles, the median and ulnar nerves, and the ulnar artery ; the posterior surface with the fore and inner surfaces of the ulna, the interosseous ligament, the pronator quadratus, the anterior radio-carpal ligaments, the fore part of the metacarpus, the flexor brevis and ad- ductor pollicis, and the two last palmar interosseous muscles. 256 MUSCULAR SYSTEM This muscle bends the third, or extreme joint of the fingers, and assists generally in the flexion of the fingers, hand, and wrist. FLEXOR LONGUS POLLICIS MANUS. This muscle, Fig. 150, /, h, Fig. 152, c, lies on the outer side of the flexor profundus ; superiorly it is attached by fleshy fibres to the fore part of the radius and interos- seous ligament, and has frequently a tendon from the inner condyle of the humerus. The fibres, /, pass obliquely into a tendon on the anterior part of the muscle ; this ten- don passes under the annular ligament of the wrist, runs between the two portions of the short flexors of the thumb, and is attached inferiorly at A, the last joint. The anterior surface of the long flexor of the thumb is connected with the flexor digitorum sublimis, flexor carpi radialis, and supinator longus muscles, the radial artery, and the anterior annular ligament of the wrist; the poste- rior surface with the radius, part of the interosseous liga- ment, the pronator quadratus, the fore part of the carpus, and the flexor brevis pollicis. The inner edge lies upon the flexor digitorum profundus. The action of this muscle bends the last joint of the thumb upon the first, the first upon the corresponding me- tacarpal bone, and the latter upon the radius; it likewise assists in the flexion of the fore-arm. OF THE UPPER EXTREMITY. 257 PRONATOR QUADRATUS, This muscle, c, d, d, as its name implies, is of a quadri- Fig. 153. lateral form, and lies close to the bone on the lower part of the fore- arm. It is attached broad, by ten- dinous and fleshy fibres, on the inner side at c, to the anterior sur- face of the ulna, extending from the lower extremity of that bone two inches up its edge. The fibres passing nearly transversely, adhere to the interosseous liga- ment, and on the outer side, at d, d, is attached to the anterior sur- face of the radius. The anterior surface of this muscle is connected with the flexor profundus, flexor longus pollicis manus, flexor carpi radialis, flexor carpi ulnaris, and with the radial and ulnar arteries; posteriorly, with the two bones of the fore-arm and the lower part of the interos- seous ligament. This muscle turns the radius to- gether with the hand inwards. V VOL. 1. 34 258 MUSCULAR SYSTEM POSTERIOR SUPERFICIAL REGION OF THE FORE-ARM. EXTENSOR DIGITORUM COMMUNIS. This'muscle, f is situated at the posterior part of the arm. It is attached superiorly to the lower part of the outer condyle of the humerus, to the aponeurosis of the fore-arm, and to the aponeurotic septa of the different muscles in that region. From these several attachments it descends vertically, and at the mid- dle of the fore-arm the fleshy mass forms four tendons, which pass under g, the annular ligament of the wrist. Below the ligament the tendons diverge, become broader, and proceed to the lower extre- mities of the metacarpal bones; they sometimes send aponeurotic bands, more or less oblique, to each other, as in the figure before us. These tendons terminate on the back of the fingers by an apo- neurotic expansion, reaching to the last phalanx. The posterior surface of the common extensor of the fingers is connected with the aponeurosis of the fore-arm ; the anterior sur- face with the supinator brevis, ex- tensores pollicis, extensor indicis, Fig. 154. \f\ ■M %. OF THE UPPER EXTREMITY. 259 the wrist, the metacarpus, the fingers, and the interossei dorsales. This muscle opens the hand, and bends the hand back upon the fore-arm. EXTENSOR PROPRIUS MINIMI DIGITI. This muscle, h, which is placed on the inner side of the preceding, is of a very slender form. It is attached superiorly to the external condyle of the humerus, and to the aponeurotic septa which separates it from the extensor communis and flexor ulnaris ; and its muscular fibres, at f constitute one mass with these muscles. Within a short distance of the wrist its fibres pass into a tendon, which is transmitted through a distinct ring at g, in the annular ligament, and arrives at the posterior surface of the little finger, to which it is attached in the same manner as the tendons of the extensor communis. The posterior surface of this muscle is connected with the aponeurosis of the fore-arm, and at the back of the hand with the integuments. The anterior surface with the supinator brevis, extensores pollicis, and extensor indicis. The outer edge is united to the extensor digito- rum communis; the inner edge to the extensor carpi ulnaris. This muscle extends the little finger, and assists in bending back the hand. EXTENSOR CARPI ULNARIS. This muscle, i, is situated on the posterior part of the arm; its shape is exhibited in the figure. It is attached superiorly to the lower part of the inner condyle of the humerus, to the intermuscular septa and aponeurosis of 260 MUSCULAR SYSTEM the fore-arm, and nearly the middle third of the posterior border of the ulna. It terminates in a strong tendon, which is inserted into the upper part of the metacarpal bone of the little finger. The posterior surface of this muscle is connected with the aponeurosis of the fore-arm, to which it adheres above ; the anterior surface with the supinator brevis, the extensor ossis metacarpi and extensor secundi internodii pollicis, and extensor proprius indicis muscles, and upon the ulna. Its outer edge with the former muscle; the inner edge with the anconeus. This muscle extends the wrist, brings the hand back- wards, and inclines it laterally towards the ulna, ANCONEUS. This muscle, Fig. 154, /, Fig. 155, a, which is situated at the outer side of the olecranon, consists of a triangular fleshy mass adhering to the capsular ligament. It is at- tached superiorly to the external condyle of the humerus by a distinct tendon; inferiorly to the superior third of the external border and surface of the ulna. The posterior surface of the anconeus is connected with the aponuerosis of the fore-arm ; the anterior surface with the orbicular ligament of the radius, the supinator radii brevis, and with the ulna. The office of this muscle is to assist in extending the fore-arm. OF THE UPPER EXTREMITY. 261 POSTERIOR DEEP REGION OF THE FORE-ARM. VW \ EXTENSOR OSSIS METACARPI POLLICIS. This muscle, b, is placed ob- liquely at the back and outer part of the fore-arm. It is attached superiorly, by a pointed extremity to the posterior surface of the ulna, to the interosseous ligament, and to the posterior surface of the radius below the attachment of the supinator radii brevis. The fleshy fibres terminate in a tendon, passing along a groove on the outer edge of the lower extremity of the radius, and is attached in- feriorly to the superior part of the metacarpal bone of the thumb. The posterior surface of this muscle is connected with the su- pinator radii brevis, extensor carpi ulnaris, extensor minimi digiti, ex- tensor digitorum communis, and extensor secundi internodii polli- cis ; at the lowest part it is in apposition with the aponeurosis o the fore-arm. The anterior sur- face is connected with a portion of the ulna above; crossing the in- terosseous ligament and the posterior surface of the radius, in the middle, and lying upon the outer surface of the radius, the tendons of the radial extensors, the radial artery, and the wrist below. 262 MUSCULAR SYSTEM This muscle extends the metacarpal bone of the thumb outwardly. It is therefore called by some anatomists abductor longus pollicis manus. EXTENSOR PRIMI INTERNODII POLLICIS MANUS. This muscle, c, is much shorter than the preceding, but of a similar form, and is situated immediately below it. It is attached superiorly by fleshy fibres to the back part of the ulna below its middle, from the interosseous ligament and radius. Its tendon follows the same direction as that of the extensor ossis metacarpi pollicis; inferiorly it is attached to the back of the first bone of the thumb, and its tendon is also continued into the second or extreme joint. The posterior surface of this muscle is connected with the extensor secundi internodii pollicis, extensor minimi digiti, and extensor digitorum communis ; at its lowest part with the aponeurosis of the fore fore-arm. The anterior surface has the same connections as the preceding muscle, excepting at its inferior extremity, where it is placed upon the first articulation of the thumb. This muscle extends the first joint of the thumb ob- liquely outwards. EXTENSOR SECUNDI INTERNODII POLLICIS MANUS. This muscle is situated below the two last. It is attached, tendinous and fleshy, to the posterior surface of the ulna, and to the interosseous ligament; its muscular fibres terminate in a tendon which passes in a distinct groove at the back of the radius. It is seen to join the tendon of the extensor primi internodii pollicis, and is OF THE UPPER EXTREMITY. 263 inserted into the back part of the last, or extreme joint of the thumb.6 The posterior surface of this muscle is connected with the extensor carpi ulnaris, the extensor digitorum communis and the extensor indicis, and at its lowest part with the integuments : the anterior surface with the extensor ossis metacarpi pollicis and extensor primi internodii pollicis, the bones of the fore-arm, the tendons of the radial exten- sors, the first metacarpal bone, and the phalanges of the thumb. This muscle extends the last joint of the thumb, and it may be observed that the extensors just described have also the power of carrying the hand outwards and back- wards. INDICATOR. This muscle, d, is placed nearer to the inner edge of the arm than the extensors of the thumb. It is at- tached superiorly to the back part of the ulna, and to the interosseous ligament. Its tendon passes through the same sheath of the annular ligament as those of the extensor digitorum communis ; and terminates at the back of the fore-finger with the tendon of the common extensor. The posterior surface is connected with the extensor carpi ulnaris, the extensor proprius minimi digiti, and the extensor digitorum communis ; the anterior surface with the ulna, the interosseous ligament, the extensor secundi internodii pollicis, the inferior extremity of the radius, and the back of the hand. The office of this muscle is to point the fore-finger, from which it takes its name. e No letter happens to mark this muscle, although it is distinctly drawn in Fig. 154, and placed between the points of c, d. 264 MUSCULAR SYSTEM MUSCLES OF THE HAND EXTERNAL PALMAR REGION. ABDUCTOR BREVIS POLLICIS MANUS. This muscle, b, c, constitutes the outermost portion of Fig. 155. the ball of the thumb. It is attached at b, to the ante- rior surface of the annular ligament of the wrist, and to the os naviculare and os trapezium; from thence it descends a little obliquely outwards. Its fibres con- verge towards each other, and are attached by a ten- don, at c, to the outer side of the extremity of the first phalanx of the thumb. In this figure the muscle is di- vided and turned backf . The anterior surface is connected with the palmar aponeurosis and the integuments; the posterior surface with the opponens and flexor brevis pollicus manus. The office of the abductor pollicis is to carry the thumb from the fingers. OPPONENS POLLICIS. This muscle, d, lies under the preceding. It is at- tached superiorly by aponeurotic fibres to the annular ligament of the wrist, to the os naviculare and the os tra- pezium. Inferiorly to the anterior and lower part of the metacarpal bone of the thumb. f Sometimes this forms two muscles, designated abductores breves pollicis manus, interior et exterior. OF THE SUPERIOR EXTREMITY. 265 The anterior surface of this muscle is covered by the preceding and by the integuments ; the posterior surface is connected with the anterior annular ligament of the carpus, the articulation of the trapezium at the first meta- carpal bone, with part of the anterior surface of that bone, and the flexor brevis pollicis manus. The office of this muscle is to bring the thumb inwards, so as to oppose the fingers, from which circumstance it has derived its name, FLEXOR BREVIS POLLICIS MANUS. This muscle, Fig. 156, e, is of a short, thick, triangular form, and is placed beneath the two preceding. It is at- tached superiorly to the under part of the annular ligament of the carpus, to the os magnum, and to the third meta- carpal bone ; inferiorly it is inserted into the sesamoid bone, which is connected by a ligament to the fore part of the upper extremity of the first joint of the thumb. The anterior surface of this muscle is connected with the tendon of the flexor brevis pollicis manus, the tendons of the flexor profundus digitorum, the two first lumbricales with an aponeurosis, the integuments, and the adductor minimi digiti; the posterior surface with the first meta- carpal bone, the two first dorsal and the first palmar interosseous muscles, and the tendon of the flexor carpi radialis. This muscle bends the first phalanx of the thumb, and the latter towards the wrist. VOL. I. 35 266 MUSCULAR SYSTEM ADDUCTOR POLLTCIS MANUS. This muscle, c, which is broad, thin, and triangular, is Fi 156 still more deeply seated than the flexor brevis. On the inner side it is attached to nearly the whole length of the me- tacarpal bone of the mid- dle finger, and crossing the metacarpal bone of the fore-finger, its fibres converge, and are out- wardly inserted by a ten- don with e, the preceding muscle, into the inner and upper part of the first bone of the thumb. The anterior surface is connected with the tendons of the flexor profundus, the two first lumbricales, and with the integuments; the posterior with the interossei and the bones of the meta- carpus. This muscle draws the thumb towards the fingers. INTERNAL PALMAR REGION. PALMARIS BREVIS. The palmaris brevis is not easily demonstrated in every subject, for it consists merely of several small fasciculi of muscular fibres, situated immediately under the skin of the palm of the hand. On the outer side it is attached to the annular ligament of the wrist, and to the palmar apo- neurosis ; on the inner side to the chorion of the skin which covers the little finger and inner edge of the hand. OF THE SUPERIOR EXTREMITY. 267 The anterior surface of this muscle is connected with the integuments ; the posterior surface with the abductor and flexor muscles of the little finger, the ulnar artery and the nerve. The office of these fibres is to contract the skin of the palm of the hand. ABDUCTOR MINIMI DIGITI. This muscle, Fig. 155, f is placed on the inner edge of the palm of the hand. It is attached superiorly to the os pisiforme, and to the adjacent annular ligament of the car- pus ; its fibres extend along the metacarpal bone of the little finger, terminating in a tendinous attachment to the inner side of the first phalanx of that finger, and in the aponeurotic expansion which covers the back part of the same finger. The anterior surface of the abductor of the little finger is connected with the preceding muscle, a very thin apo- neurosis, and with the integuments ; the posterior surface with the adductor ossis metacarpi minimi digiti. The action of this muscle draws the little finger inwards and forwards, and separates it from the other fingers. FLEXOR PROPRIUS MINIMI DIGITI. This muscle, Fig. 155, g, is situated by the side of the preceding. It extends from the os cuneiforme, and from the annular ligament of the carpus to the upper portion of the first phalanx of the little finger, to which it is at- tached with the preceding muscle by a round tendon; its connections are the same as the preceding muscle. This muscle bends the first joint of the little finger, and assists the adductor. 268 MUSCULAR SYSTEM ADDUCTOR OSSIS METACARPI MINIMI DIGITI^. This muscle, Fig. 156, a, is almost concealed by the two muscles last described. It is attached superiorly, by fleshy fibres, to the os cuneiforme and annular ligament of the carpus; it forms a thick mass, which is attached infe- riorly by a tendon to the fore part of the metacarpal bone of the little finger. The posterior surface is connected with the last inter- osseous muscle, the fourth metacarpal bone, and the ten- don of the flexor sublimis, which passes to the little finger. This muscle carries the metacarpal bone of the little finger outwards, and assists the flexor. MIDDLE PALMAR REGION. LUMBRICALES11. The lumbricales are four small muscles, Fig. 155, a, a, a, a, situated in the palm of the hand. They are attached superiorly to the tendons of the flexor digitorum profundus perforans ; each muscle has a tendon, which passes along the side of the finger, and is attached inferiorly to the back part of the first joint. The anterior surface is connected with the tendons of the flexor digitorum profundus, the palmar aponeurosis, and the collateral vessels and nerves of the fingers; the posterior surface with the interosseous muscles, the infe- rior transverse metacarpal ligament, and the phalanges. These muscles bend the first phalanx: they are small and appear insignificant as flexors, when compared with the powerful muscles already described, but they are in- g This muscle is frequently designated opponens minimi digiti. h These derive their name from their resemblance to the lumbricus or earth-worm. OF THE SUPERIOR EXTREMITY. 269 dispensably necessary in the performance of the rapid movements of the fingers, as in playing on musical instru- ments, etc. Hence CowPERgave them the name of mus- culi fidicinales. INTEROSSEI. These are seven little muscles named interossei, situated in the intervals of the metacarpal bones : four, Fig. 157, a, a, a, a, on the back of the hand, and three, Fig. 158, a, b, d, in the palm : the latter are not seen till the other mus- cles of the thumb and fingers are removed ; they are desig- nated adductors, and abductors, according to their uses. I. ABDUCTOR INDICIS. Fig. 157. Fig. 158. This muscle, c, Figs. 157 and 158, is of a triangular form; it is attached to the outer edge of the metacarpal 270 MUSCULAR SYSTEM bone of the fore-finger, and to the upper part of the inner edge of the metacarpal bone of the thumb. The two fasciculi unite into a tendon, which terminates on the outer side of the upper extremity of the first phalanx, and the extensor tendon of the fore-finger. The posterior surface of this muscle is connected with the integuments; the anterior with the first lumbricalis, the flexor brevis, b, the abductor pollicis, and the integu- ments. This muscle approximates the fore-finger to the thumb, and inclines the metacarpal bone inwards. II. ADDUCTOR INDICIS. This muscle, Fig. 158, d, is placed in the palm of the hand; it is attached superiorly to the inner side of the metacarpal bone of the fore-finger ; inferiorly by a tendon in the same manner as the preceding. The anterior surface of the adductor indicis is con- nected with the flexor brevis and adductor pollicis; the inner surface corresponds with the next muscle. The action of this muscle carries the fore-finger inwards. III. ABDUCTOR DIGITI MEDII. This muscle, Fig. 157, is seen at the back of the hand. It is attached to the inner side of the second and third metacarpal bones, and terminates by a tendon, like the preceding, which is attached to the outer side of the first phalanx of the middle finger, and its extensor tendon. The posterior surface of this muscle is connected with the integuments, the tendons of the extensor muscles of the fore-finger, and with an aponeurosis which passes from the second to the third metacarpal bone; the anterior surface with the flexor brevis and adductor pollicis. This muscle draws the middle finger outwards. OF THE SUPERIOR EXTREMITY. 271 IV. ADDUCTOR DIGITI MEDII. This muscle, Fig. 157, is also situated at the back of the hand. It is attached to the inner side of the third and fourth metacarpal bones, and terminates like the others in a tendon which is inserted into the inner side of the upper extremity of the first phalanx and extensor tendon of the middle finger. The posterior surface of this muscle is connected with the integuments and tendons of the common extensors of the fingers. This muscle carries the middle finger towards the ring finger. V. ABDUCTOR DIGITI ANNULARIS. This muscle, Fig. 158, b, is placed in the palm of the hand ; it is attached to the outer side of the fourth meta- carpal bone ; and its tendon is inserted into the outer side of the first phalanx and extensor tendon of the ring finger. The anterior surface is connected with the lumbricales muscles and tendons of the flexor profundus. This muscle draws the ring finger towards the middle finger. VI. ADDUCTOR DIGITI ANNULARIS. This muscle, Fig. 157, is situated on the back of the hand. It is attached to the inner side of the fourth meta- carpal bone, terminating in a tendon which is inserted into the inner side of the ring finger. The posterior surface of this muscle is connected with an aponeurosis which passes from the fourth to the fifth metacarpal bone, the extensor tendons of the little finger, 272 MUSCULAR SYSTEM and the integuments: the anterior surface is concealed above by the interosseous muscle of the little finger, but below appears between it and the preceding muscle. This muscle brings the ring finger towards the little finger. VII. ABDUCTOR MINIMI DIGITI. This muscle, Fig. 158, a, is seen in the palm of the hand. It is attached to the outer surface of the fifth metacarpal bone; its tendon is inserted into the outside of the first phalanx and the extensor tendon of the little finger. The anterior surface of this muscle is connected with the adductor ossis minimi digiti; the outer surface cor- responds with the preceding muscle. The action of this muscle carries the little finger out- wards. THE ENVELOPING APONEUROSIS OF THE UPPER EXTREMITY. The muscles of the arm are covered by a delicate cel- lular tissue, very different from aponeurosis, and therefore is usually in dissections taken off with the integuments. But on the fore-arm we find a strong fascia or aponeurosis, investing all the superficial muscles. This external apo- neurosis is continued from the intermuscular aponeurosis, which pass down to the condyles of the humerus. It is attached to the condyles and to the olecranon, and on the back part receives a great addition of fibres from the tendon of the triceps. On the fore part of the arm it appears to be a continuation of the aponeurotic insertion of the biceps, and is attached to all the muscles by septa, or fibrous partitions. The sheath descends along the OF THE SUPERIOR EXTREMITY. 273 fore-arm, adhering to the whole inner edge of the ulna, and arriving at the wrist, is continued into the annular ligaments. The outer surface is covered by skin, cellular tissue, adipose substance, and by the superficial veins, nerves, and lymphatics of the arm. It appears to form thin sheaths for these different organs; it sends also be- tween them, and especially above them, areolae and arches, through which the branches of superficial veins and nerves pass. The fibres have no constant direction, but cross each other in all directions, and leave between them small openings, which are traversed by blood-vessels. VOL. I. 36 274 MUSCULAR SYSTEM CHAP. VI. MUSCLES OF THE INFERIOR EXTREMITY. REGION OF THE HIP. MUSCLES OF THE HAUNCH AND THIGH GLUTEUS MAXIMUS. Fis. 159. This muscle is placed at the back part of the hip, cover- ing all the muscles situated on that part. A correct idea of its form may be had from the annexed representation. OF THE INFERIOR EXTREMITY. 275 It is attached superiorly, at a, to the posterior crest of the ilium; at b, to the posterior surface of the sacrum; at c, to the border of the os coccygis, and to the posterior sur- face of the sacro-sciatic ligament; the fleshy fibres pass obliquely downwards and forwards, forming a very broad, thick, coarse muscle ; its fasciculi gradually converging, terminate in a strong flat tendon, which is attached infe- riorly at d, e, the upper and outer part of the linea aspera of the femur. A great portion of tendinous fibres also unite it to the aponeurosis of the thigh. The posterior surface of this muscle is covered by an extremely thin lamina of the fascia lata, adipose tissue, and skin. The anterior surface is applied to the ilium, sacrum, and os coccygis ; the attachments of the sacro-spinalis, the gluteus medius, pyriformis, gemelli, obturator internus, and quadratus femoris muscles; to the sciatic nerve, the tuber ischii, the posterior sacro-sciatic ligament, the upper ex- tremity of the biceps, semimembranosus and semitendi- nosus, the great trochanter, and to the triceps adductor muscles. The office of the gluteus maximus is to extend the thigh by drawing it backwards and somewhat outwards. It extends likewise the pelvis on the thigh in standing; and assisted by the other glutei in progression, it maintains the equilibrium of the body on the lower extremity, which rests on the ground. 276 MUSCULAR SYSTEM GLUTEUS MEDIUS. Fig. 160. This muscle, a, is broad, strong, and radiated; it is situated under the preceding, except at its anterior part, where it is covered only by aponeurosis. Superiorly it is attached by fleshy fibres to b, b, the whole of the outer edge of the crista of the ilium, and to the dorsum of that bone ; its converging fibres, a, are collected, and terminate in a broad aponeurosis, which is somewhat concealed in its substance, but is converted into a tendon, and is inferiorly inserted into the upper part of c, the great trochanter. The outer surface of this muscle is connected with the posterior half of the gluteus maximus, and its anterior with OF THE INFERIOR EXTREMITY. 277 the fascia lata; the inner surface with the iliac bone, the gluteus minimus, pyramidalis, triceps extensor muscles, and the gluteal artery. The anterior edge is connected above with the tensor vaginae femoris, but is separated below by an interval occupied by a great quantity of cel- lular tissue and branches of the external circumflex artery. The posterior edge, at its upper part, is parallel to the pyriformis muscle. The gluteus medius draws the thigh outwards and a little backwards. It also acts in standing and in progression. GLUTEUS MINIMUS. Fig. 161. This muscle, a, a, b, is smaller than the gluteus medius, and is entirely concealed until that muscle is raised from its connections. A synovial bursa is found between their 278 MUSCULAR SYSTEM tendons. The gluteus medius is attached superiorly by fleshy radiating fibres at a, a, to the semicircular ridge of the ilium, and to the dorsum of that bone below the ridge. Its fasciculi descend and are collected together, terminat- ing inferiorly in a strong tendon, which is attached at b, to the anterior and superior part of the trochanter major. The outer surface of the gluteus minimus is connected in the greater part of its extent with the preceding mus- cle ; posteriorly with the pyriformis; the inner surface with the ilium, the fibrous capsule of the articulation of the hip, the curved tendon of the rectus femoris, and witn a small part of the triceps extensor cruris. This muscle assists the two former muscles. OF THE INFERIOR EXTREMITY. 279 PELVI-TROCHANTERIC REGION. PYRIFORMIS. Fig. 162. This, like the other small muscles of the hip, cannot be demonstrated till the gluteus maximus is removed. It lies behind and below the gluteus medius, but is not at all co- vered by it. On the one part,' it is attached at a, by three fleshy portions, to the concave surface of the sacrum, and becoming round and tapering, it passes out of the pelvis below the nitch of the posterior part of the ilium, and above c, the superior sacro-sciatic ligament; that part which 280 MUSCULAR SYSTEM passes out of the pelvis is seen in Fig. 161, at e, termi- nating in a round tendon, and is inserted into the cavity at the root of b, the trochanter major. In the pelvis, the anterior surface is connected with the rectum, the sciatic plexus, and the hypogastric vessels. After leaving that cavity, it is in contact with the ilium, the capsule of the hip joint, and the gluteus minimus. The posterior surface is connected with the sacrum and the gluteus maximus; the upper edge with the gluteal artery, gluteus medius, and gluteus minimus; the lower edge with the anterior sacro-sciatic ligament, and is separated from the superior gemellus by the sciatic nerve. This muscle turns the thigh outwards: in some degree it has the power of turning the pelvis on the thigh. OBTURATOR INTERNUS. The superior part of this muscle, Fig. 162, c, is situated within the pelvis; it is attached by radiated fibres to more than one-half of the margin of the obturator foramen, and to the inner surface of the aponeurosis which fills up that hole. Its fibres concentrate into a round tendon, f, Fig. 160, which passing over the ischium between the spine and tuber of that bone, leaves the cavity of the pelvis, is inclosed in the sheath of the gemelli, e, g, (as seen in Fig. 161;) finally it is attached with them at the root of c, the great trochanter. Where the obturator bends there is a synovial capsule, lining the cartilaginous layer of the lesser sciatic notch, and reflected over the tendon. The outer surface of the obturator internus is connected with the ilium, pelvis, obturator ligament, sciatic nerve, and gluteus maximus ; the inner surface with the aponeu- rosis to which the levator ani is attached, and with the capsule of the articulation of the hip. OF THE INFERIOR EXTREMITY, 281 The office of this muscle is to rotate the thigh and leg outwards, and to draw it in the same direction. OBTURATOR EXTERNUS. Fig. 1G3. This muscle covers the external obturator foramen. It is not distinctly seen until all the muscles which run from the pelvis to the upper part of the thigh are removed. Inwardly, it has a fleshy attachment, at a, to the circum- ference of the obturator foramen, and to the external sur- face of the obturator aponeurosis; its fibres are directed outwards through the notch placed between the inferior margin of the acetabulum and the tuberosity of the ischium, pass round the cervix of the femur, adhering to e, the capsular ligament, and terminate in a tendon which is at- tached outwardly, at the root of the trochanter major, vol. i. 37 282 MUSCULAR SYSTEM immediately below the gemelli, as seen in Fig. 160, below the letter g. The anterior surface of the obturator externus is con- nected with the pectineus, the adductors, and the quadra- tus femoris; the posterior surface with the ilium, the obturator ligament, and the capsule of the articulation of the hip. The office of this muscle is to rotate the thigh obliquely outwards. GEMELLUS SUPERIOR1. This muscle, Fig. 160, e, is placed below the preceding. It is short, flat, and broad, thicker in the middle than at the extremities. It is attached on the inner side to the external border of the sciatic spine, then proceeds trans- versely outwards, and embraces the tendon of/, the obtu- rator internus, and becomes attached outwardly to the upper part of the inner surface of the great trochanter. The posterior surface of the gemellus superior is con- nected with the sciatic nerve and gluteus maximus ; the anterior surface with the ilium and the capsule of the arti- culation of the hip. GEMELLUS INFERIOR. This muscle, Fig. 160, g, has the same form, attach- ments, and connections, as the gemellus superior. The two tendons of the gemelli unite behind that of the obtu- rator internus, so as to form a kind of channel. These muscles roll the thigh outwards, and draw the one from the other. i This muscle, with the following, are frequently designated under the general name of musculi gemini. OF THE INFERIOR EXTREMITY. 283 QJJADRATUS FEMORIS. This muscle, Fig. 161, is situated below the inferior gemellus. On the inner side, it is attached, at c, to the ischium, between its tuberosity and the obturator foramen; on the outer side, its fibres run transversely, and are at- tached at the back part of the femur to a rough line, which extends from the root of the great to that of d, the small trochanter". The posterior surface of the quadratus femoris is con- nected with the sciatic nerve, the gluteus maximus, the semimembranosus, and the adductor magnus muscles; the anterior surface with the obturator externus, the extremity of the tendon of the psoas magnus, and the posterior part of the small trochanter. The office of this muscle is to turn the lower extremity outwards. j This muscle is also shewn in Fig. 163, at 6. 284 MUSCULAR SYSTEM ANTERIOR FEMORAL REGION. Fig. 164. SARTORIUS. This muscle, b, which is the longest of the human body, is situated on the front and inner part of the thigh, be- fore the other muscles. Su- periorly it is attached, at h, to the anterior superior spi- nous process of the ilium; crosses the thigh obliquely, passes behind the inner con- dyle of the femur, at e, and is inserted inferiorly by a broad tendon, at i, to the inner side of the head of the tibia, near the inferior part of its tubercle. The anterior surface of the sartorius is connected with the fascia lata; the pos- terior surface from above downwards with the psoas magnus and iliacus internus, the rectus femoris, triceps extensor cruris, adductor lon- gus, adductor magnus, and gracilis muscles ; with the crural artery about the mid- dle of the thigh; and at its lower part with the internal lateral ligament of the arti- OF THE INFERIOR EXTREMITY. 285 culation of the knee. The inner edge of the superior part of this muscle forms with the adductor longus a trian- gular space, in which the crural artery, vein, and nerve, is situated. The action of this muscle brings the leg obliquely in- wards, as when tailors cross their legs at work; indeed, from this circumstance the muscle obtains its name. Its continued contraction will also bend the thigh on the pelvis. RECTUS FEMORIS. The rectus femoris is situated immediately in front of the thigh ; its fibres are penniform. Superiorly it is at- tached by a tendon to the anterior inferior spinous process of the ilium, and by another strong tendon to the dorsum of that bone a little above the edge of the acetabulum, and is also adherent to the capsular ligament of the hip joint. These two tendons unite and form a fleshy mass, which terminates inferiorly in a flat tendon at f and is inserted into the upper part of the patella, g, where a thin apon- eurosis is continued over that bone, and becomes ligamen- tous at h, connecting the lower part of the patella to the tibia. Thus, virtually the rectus is attached to the large bone of the leg. The anterior surface of the rectus femoris is connected with the fascia lata, iliacus externus, and sartorius mus- cles ; the posterior surface with the articulation of the hip, the external circumflex vessels, and the triceps extensor cruris. The office of this muscle .[is to extend the leg on the thigh, and the thigh on the pelvis ; when standing, it assists in fixing the body. 286 MUSCULAR SYSTEM TRICEPS EXTENSOR This muscle embraces the Fig. 165. C Vastus externus, ElURIS. < Vastus internus, ( Crurceus. femur from the base of the trochanters to the patella. The older writers described it as three distinct muscles; and as its upper part is divi- ded into three fasciculi, the distinction is here retained. 1st. The external fascicu- lus, or vastus externus. This portion forms the fleshy mass which occupies the outer side of the thigh bone; it is attached superiorly, by ten- dinous and fleshy fibres, at a, to the anterior surface of the great trochanter, to the outer border of the linea aspera, and to the oblique line run- ning to the external condyle. The fleshy fibres pass for- wards, and are connected at b, to the tendon of the cru- raeus, and inferiorly, at c, to the side of the patella: part of it also ends, at d, in an a- poneurosis which passes over the side of the knee, is fixed to the head of the tibia, and continued to the leg. OF THE INFERIOR EXTREMITY. 2B7 2nd. The internal fasciculus, or vastus internus, covers the inner part of the femur, in the same manner as the preceding portion does the outer side. It is attached by aponeurotic and fleshy fibres, at /, to the fore part of the minor trochanter; its fibres are continued along the inner border of the linea aspera, and the oblique line running to the inner condyle, taking a direction downwards and for- wards ; they are then connected, at b, to the tendon of the cruraeus, and inferiorly to the side of the patella, c, and to the aponeurosis of the leg. 3rd. The middle fasciculus, b, is called the cruraus vel cruralis, the principal part of which is concealed by the fleshy masses of the vasti, and is connected intimately with them. It is attached superiorly between the trochanters of the femur and the fore part of that bone almost to its inferior extremity. As before stated, the sides are united to the vasti fasciculi. The front is covered by the rectus, the tendon of which, at g, joins it near the lower part of the thigh, terminating with it in c, the patellak. The anterior surface of this muscle is connected exter- nally and above with the tendons of the gluteus maximus and minimus, farther down with the fascia lata and its ten- sor muscles, and at its lowest part with the short portion of the biceps. In the middle it is in connection with the external circumflex vessels ; internally, the fascia lata, the crural artery, and the sartorius, are in contact with it. The posterior surface is connected with the whole surface of the shaft of the thigh bone, but is separated below from it by a mass of cellular and adipose tissue. The office of the triceps extensor muscle is to extend the leg on the thigh, and the latter on the former. k There are frequently found some fasciculi of muscular fibres under the middle portion, and attached to the capsule of the knee joint, which have been considered by some anatomists as a separate muscle, under the name of subcruraus. 288 MUSCULAR SYSTEM INTERNAL FEMORAL REGION PECTINEUS. This muscle, d, is situated at the superior part of the 166. thigh, and is of a flat, long, and triangular figure. It is attached superiorly by apon- eurotic adhesions to the brim of the pelvis; inferiorly by means of a tendon to the li- nea aspera, immediately be- low the trochanter minor. The anterior surface of the pectineus is connected with the fascia lata and the crural vessels and nerves; the posterior with the pubis, the articulation of the hip, the obturator externus, the ad- ductor brevis muscles, and the obturator vessels and nerves. The inner border is a little covered by the ad- ductor longus ; the outer is parallel to the psoas magnus. The office of this muscle is to bend the thigh, and to rotate it, as when we turn out our toes. It also bends the pelvis upon the thigh, or preserves it in its upright position. k h i OF THE INFERIOR EXTREMITY. 289 GRACILIS. The gracilis, which is situated on the inner side of the thigh, is a long, thin, flat muscle. Superiorly it is attached at a, by an aponeurosis or flat, thin tendon, to b, the ramus of the os pubis, near the symphysis ; descending in a direct course by the inside of the thigh, it tt rminates at h, in a tendon, which passes behind the inner condyle of the femur, and is attached inferiorly to the inside of the tibia below the tendon of i, the sartorius, and above that of k, the semitendinosus. The inner surface is connected with the fascia lata and the sartorius ; the outer with the adductors, and the semi- membranosus muscles, and the internal lateral ligament of the knee joint. This muscle, like the sartorius, brings the thigh inwards and forwards; it acts also as a flexor of the leg and thigh. ADDUCTORS OF THE THIGH. The adductor muscles of the thigh consist of three dis- tinct muscles, though they are frequently described as one under the name of triceps adductor femoris. ADDUCTOR LONGUS. This muscle, Fig. 167, is placed between the pectineus and gracilis. It is attached superiorly, by a short and strong tendon at b, to the upper and inner part of the os pubis, near its symphysis ; the fibres, a, descend obliquely, and are inferiorly attached by an aponeurosis at c, to the middle of the linea aspera, occupying rather more than one-third of its length. The anterior surface of the adductor longus is con- vol. i. 38 290 MUSCULAR SYSTEM nected with the fascia lata, the sartorius, and the femoral artery ; the posterior surface with the two other adductor muscles, and is almost inseparably united to them below. The outer border is parallel to the pectineus muscle; the inner is concealed by the gracilis. ADDUCTOR BREVIS. This muscle is situated behind the preceding; it is of a triangular, flat figure, and is attached superiorly, by tendi- nous and fleshy fibres, to the pubes between the symphysis and obturator foramen ; inferiorly, to the upper third of the linea aspera, where its insertion is blended with the adductor longus, the adductor magnus, and the pectineus. The anterior surface of the adductor brevis is connected with the preceding muscle and the pectineus; the poste- rior with the adductor magnus. Inferiorly it is united to the gracilis ; and externally to the tendon of the psoas magnus, the iliacus internus, and to the obturator externus. OF THE INFERIOR EXTREMITY. 291 ADDUCTOR MAGNUS. The adductor magnus Eig. 167. occupies nearly the whole inner part of the thigh ; it is situated behind and below the other two adductors, and separates the anterior and posterior parts of the thigh. It is attached supe- riorly, at e, to the inferior part of the anterior surface of the ramus of the pubes ; at b, to the anterior surface of that of the ischium, and to the external border of its tuberosity; the fibres run in- wards and downwards, hav- ing various degrees of ob- liquity, and are attached in- feriorly to the whole length of the linea aspera, to the oblique ridge above the in- ternal condyle of the os fe- moris, and by a long round tendon to the upper part of the condyle, where the tendon is united to the ad- ductor longus. There is a perforation in the tendon of this muscle at i, near the bone through which the femoral artery passes in its course towards the ham. The anterior surface of this muscle is connected with 292 MUSCULAR SYSTEM the two preceding, the sartorius, and the femoral artery ; the posterior surface with the semitendinosus, semimem- branosus, biceps, gluteus maximus, and the sciatic nerve. The inner border is much thicker above than below, and is connected with the fascia lata and gracilis. The office of the adductors is—1st, to move the thigh and leg inwards ; 2nd, to roll it outwards ; 3rd, to bend the thigh on the pelvis; and lastly, to keep the pelvis firm in the erect position of the trunk. The action of the fibres vary according to the obliquity of their attachments. OF THE INFERIOR EXTREMITY. 293 POSTERIOR FEMORAL REGION, BICEPS FEMORIS. The biceps femoris is si- tuated at the back part of the thigh, and forms the outer hamstring. It is divided in- to two portions, one long and the other short. The long portion is attached superiorly at a, by a tendon, to the outer part of the tuberosity of the ischium, and descend- ing, forms a thick, fleshy mass ; its short portion, b, is fixed by tendinous and fleshy fibres to the linea aspera im- mediately below the gluteus maximus, and to the oblique ridge passing from the con- dyle, where it is connected with the fibres of the vastus externus. The two heads are united at an acute angle a little above the external condyle of the femur, and terminate in a strong tendon, c, which is attached at d, to the outside of the head of the fibula. The posterior surface of this muscle is connected with Fia. 168. 294 MUSCULAR SYSTEM the gluteus maximus and the fascia lata; the anterior sur- face with the semitendinosus, triceps, and adductor magnus muscles, the sciatic nerve, the femur, and the external lateral ligament of the knee. The long portion is placed over the short portion, which is connected with the exter- nal superior articular artery and the external head of the gastrocnemius. The inner border unites with the preced- ing muscle to form the ham. The biceps is a powerful flexor of the leg upon the thigh, or the latter upon the leg ; its long portion is capable of extending the thigh upon the pelvis, or of keeping the pelvis erect. It also assists in turning the leg outwards. SEMITENDINOSUS. This muscle, e, is placed between the biceps femoris and gracilis; we may also see it in Fig. 166, c, k; it is attached superiorly, in common with the biceps, by apon- eurotic fibres to the tuberosity of the ischium ; it has also some fleshy fibres fixed to that projection more outwardly, and is connected for several inches, at /, with the com- mencement of the biceps. The fleshy mass runs down the back of the thigh, forms a long round tendon, g, which passing round the inner side of the knee, becomes flat- tened, and is reflected forward to be inserted into the inner side of the ridge of the tibia, a little below the tubercle, and is connected with the under edge of the tendon of the gracilis, marked in this figure h. The posterior surface of the semitendinosus is connected with the fascia lata, and a little at its upper part with the gluteus maximus; the anterior surface with the semimem- branosus and adductor magnus. The office of this muscle is to bend the leg backwards OF THE INFERIOR EXTREMITY. 295 and a little inwards, and to assist in keeping the pelvis erect. SEMIMEMBRANOSUS. This muscle, i, is situated behind the preceding muscle, and with it properly forms the inner hamstring. The ten- dons of the sartorius and gracilis are sometimes enumerated as part of the inner hamstring, but they lie more ante- riorly. The upper portion is best displayed in Fig. 166, and is superiorly attached, at d, to the outer part of the tuberosity of the ischium. It forms a fleshy mass in the middle and back part of the thigh ; and inferiorly termi- nates obliquely in a flat tendon, Fig. 168, i, which passing behind the inner condyle, is spread out at k, in an apon- eurotic expansion, which covers and strengthens the cap- sule of the knee joint, and is attached, at I, to the inner and back part of the head of the tibia. The offices of this muscle are the same as those of the preceding muscle. The posterior surface of the semimembranosus is con- nected with the biceps, semitendinosus, and fascia lata; the anterior surface with the quadratus femoris, adductor magnus, and internal head of the gastrocnemius, popliteal artery, and the knee joint. Its outer border is connected with the sciatic nerve, and concurs with the biceps to form the cavity of the ham ; the inner border is covered by the gracilis and the cavity of the fascia lata. TENSOR VAGINA FEMORIS. This muscle, Fig. 164, a, is situated at the upper and outer part of the thigh; it is attached externally to the anterior and superior iliac spine, between the sartorius 296 MUSCULAR SYSTEM and gluteus medius, by a very short tendon; the fleshy fibres descend nearly vertically, diverging as they proceed, and about three inches above the great trochanter termi- nate in the laminae of the femoral aponeurosis. The outer surface is connected to a thin lamina of the aponeurosis of the thigh ; the inner to another aponeurotic plate, which separates the rectus femoris from the triceps extensor cruris. It also covers a portion of the gluteus medius and gluteus minimus muscles. The principal action of this muscle is to stretch the aponeurosis which envelopes the muscles of the thigh. It also carries the limb outwards, separating it from the other. APONEUROSIS OF THE THIGH. The inferior extremities, like the superior, are enveloped by a strong tendinous web. In the thigh it is frequently termed the fascia lata femoris; and is composed of strong tendinous and ligamentous fibres, which cover all the mus- cles, and indeed sends septa or partitions between them. On the outer part, it is very strong and tendinous ; but in front, and on the inner part, it is thin, and composed of a mere condensed cellular membrane. Superiorly and anteriorly the aponeurosis of the thigh is continuous with the fibres of the crural arch, and is fixed posteriorly to the sacrum and os coccygis; on the outer side, it is inserted into the crest of the ilium ; on the inner side, it is continuous with the ligaments of the pubis. Inferiorly, this aponeurosis is blended round the knee with that of the leg. There is a considerable opening beneath the crural arch, through which the crural vein passes. This opening is formed in the following manner. The aponeurosis being composed of two portions, the iliac and pubic, the former OF THE INFERIOR EXTREMITY. 297 is folded in the shape of a sickle at that part where it ceases to be united to the crural arch. The concavity of this fold looks downwards and inwards, and is termed the falciform process; the latter, or pubic portion, coming from the pubes, passes over the pectineus and adductors, and unites with the iliac portion beneath the point where the saphena vein joins the femoral. VOL. I. 39 298 MUSCULAR SYSTEM MUSCLES OF THE LEG. ANTERIOR REGION OF THE LEG. TIBIALIS ANTICUS. This muscle, Fig. 169, a, 5, is situated quite superficially on the fibular side of the tibia. It is at- l tached superiorly to the external tuberosity and outer surface of that bone, and to nearly half of the interosseous ligament, g; from these surfaces it continues to ad- here down two-thirds of the length of the leg. Its fibres also are at- tached to the inner surface of the aponeurosis of the leg, and to the intermuscular septa. The fleshy mass descends obliquely, and form- ing a strong tendon, crosses from the outside to the fore part of the tibia,- and passing through a dis- tinct ring of (b) the annular liga- ment, near the inner ankle, and running over the astragalus and 7')-4JilWn> os naviculare, it is inferiorly in- serted, at c, into the os cuneiforme internum, and the posterior extre- mity of the metatarsal bone of the great toe. The anterior surface of this muscle, at its superior part, firmly adheres to the aponeurosis of the tibia; it is also connected OF THE INFERIOR EXTREMITY. 299 with the annular ligament of the tarsus, and the dorsal aponeurosis of the, foot; on the inner side with the tibia; on the outer with the extensor communis digitorum pedis, extensor proprius pollicis pedis, the anterior tibial vessels and nerves. The posterior border is placed upon the in- terosseous ligament, the tibia, the articulation of the ankle, and the upper and inner part of the tarsus. The office of the tibialis anticus is to bend the foot up- wards and inwards. It is also a flexor of the leg on the foot, and it prevents the limb from falling backwards in the standing posture. PERONEUS TERTIUS. The fleshy fibres of this muscle, d, e, and Fig. 171, e,/, are almost inseparably connected with the long extensor of the toes, and indeed it may be said to be the outer por- tion of it. It is attached superiorly to the inferior third of the anterior border of the fibula, and to the neighbouring part of the internal surface. It sends its fleshy fibres for- wards to a tendon which passes under the annular ligament of the tarsus in the same groove as those of d, Fig. 171, and is attached inferiorly, at e, to the posterior part of the metatarsal bone of the little toe. The outer surface of the peroneus tertius is connected with the aponeurosis of the leg; the inner surface with the extensor communis digitorum pedis. In the foot it passes over the extensor brevis digitorum pedis and the first metatarsal bone : its posterior border is placed upon the fibula and interosseous ligament. The office of this muscle is to bend the foot upon the leg, raising its outer edge; it also bends the leg on the foot. 300 MUSCULAR SYSTEM EXTENSOR LONGUS DIGITORUM PEDIS. Fig. 170. This muscle, a, is placed entirely superficial between a, the tibialis anticus, Fig. 169, and d, e, the peroneus tertius, being firmly connect- ed to them by the intermus- cular membranes. In the figure before us it is repre- sented drawn aside by a hook at a; superiorly it is attached by aponeurotic and fleshy fi- bres, at b, to the external tuberosity of the tibia; to the head, and to almost the whole anterior part of the internal surface of the fibula, to the interosseous ligament, and to the aponeurosis of the leg, and the intermuscular septa. The fleshy fibres proceeding from these different direc- tions, pass obliquely into a tendon marked d, Fig. 171, which below the middle of the leg is divided into four continuous portions, and pass under c, Fig. 170, the annu- lar ligament, then over the upper part of the foot, and are distributed to the posterior extremity of the first phalanx of the four small toes, by flat tendons, which afterwards expand upon the upper surface of the toes. OF THE INFERIOR EXTREMITY. 301 The anterior border of this long extensor of the toes is connected with the aponeurosis of the tibia, the annular ligament of the tarsus, and the integuments ; the posterior border with the fibula, the interosseous ligament, the tibia, the ankle joint, and the extensor brevis digitorum and the toes. The inner corresponds to the tibialis anticus and extensor proprius pollicis pedis. The outer is intimately united above with the peroneus longus, at the middle with the peroneus brevis, and below with the peroneus tertius : see Fig. 171. The office of this muscle is to extend all the joints of the small toes, and to assist in raising the foot. EXTENSOR PROPRIUS POLLICIS PEDIS. The fleshy fibres of this muscle, d, are situated between the long extensor of the toes and the anterior tibial muscle, and cannot be exhibited until those muscles are separated from each other ; but the tendon is superficial, passing between the tendons of those two muscles. It is attached superiorly to the anterior part of the middle third of the inner surface of the fibula, and to the adjacent part of the interosseous ligament; the muscular fibres terminate in a tendon which passes in a particular groove under c; the annular ligament runs along the inner edge of the foot, and is inserted, at e, into the upper surface of the posterior extremity of the last phalanx of the great toe. The inner surface of this muscle is connected with the tibialis anticus, and anterior tibial vessels and nerves ; the outer surface with the extensor communis digitorum ; the anterior border is concealed above between the tibialis anticus and extensor digitorum, and is covered by the 302 MUSCULAR SYSTEM aponeurosis of the tibia and the integuments. The poste- rior border is placed on the fibula, the interosseous liga- ment, the tibia, the anterior tibial artery, the articulation of the tibia and tarsus, and upon the back of the foot and great toe. The office of this muscle is to extend the great toe; it also bends the leg on the foot and the foot on the leg. OF THE INFERIOR EXTREMITY. 303 PERONEAL PERONEUS Fig. 171. don of the peroneus longus channel in the os calcis and < across the sole of the foot, a REGION. LONGUS. This muscle, g, and Fig. 174, d, is situated at the external part of the leg. Its fleshy fibres are quite superficial. It is attached superiorly to the outer side of the upper extremity of the fibula at g, and to one- third of its length down- wards, to the crural apon- eurosis and to the aponeu- rotic septa placed between the soleus and flexor lon- gus pollicis pedis on one side, and the extensor lon- gus pollicis pedis on the other side; the fibres run obliquely outwards into a tendon, which passes be- hind the outerankle through a groove which is common to it with the peroneus ter- tius : thus, at the lower end of the fibula, these ten- dons are bound down by a tendinous bridle. The ten- is then conducted through a s cuboides, extends obliquely id is attached to the posterior 304 MUSCULAR SYSTEM extremity of the metatarsal bone of the great toe, and to the os cuneiforme internum1. The outer surface of the peroneus longus is connected with the aponeurosis of the tibia; the inner surface with the fibula, extensor digitorum communis, and peroneus brevis-; the posterior surface corresponds to the soleus above and below the flexor longus pollicis. The several connections of the tendon have already been noticed. The office of this muscle is to turn the foot outward, and to assist in extending it. PERONEUS BREVIS. This muscle is situated between the extensor longus digitorum and peroneus longus; its muscular fibres are concealed by those of the latter muscle. It is attached superiorly to the inferior half of the outer surface of the fibula, and to the intermuscular aponeurosis, and to the aponeurosis of the leg. The fibres run obliquely towards a tendon which passes in a groove of the fibula at the outer ankle, where it is inclosed in the same tendinous ring with the peroneus longus. It is continued through a channel on the outside of the os calcis, and is attached to the supe- rior part of the posterior extremity of the metatarsal bone of the little toe : see Fig. 174, g. The outer surface of the peroneus brevis is connected with the aponeurosis of the tibia and peroneus longus : the inner surface with the fibula, the extensor digitorum com- munis, and the peroneus tertius above, and with the flexor longus pollicis below. The office of this muscle is to turn the foot outwards, and somewhat to extend it. I This insertion is distinctly seen in Fig. 174. OF THE INFERIOR EXTREMITY. 305 POSTERIOR REGION OF THE LEG. GASTROCNEMIUS EXTERNUS ET INTERNUS. These muscles are extremely large Fig. 172. and strong, and principally form the calf of the leg. They are separated above into two flat fleshy masses, but are united below, where they present the strongest tendon of the whole body. The internal muscle is attach- ed superiorly, at a, to the back part of the inner condyle of the femur ; the external muscle is attached in the same manner, at b, to the external condyle. Each of these muscles forms a large fleshy mass, which is united below the ham in a central fibrous line near the middle of the leg: at c, they become a broad apon^ eurosis, which, as it approaches the heel, forms with the two lendons of the subsequent muscles a strong round chord, at d, termed the tendo-Achil- lis, which is fixed at e, the posterior extremity of the os calcis. The anterior surface of the gas- trocnemii is connected with the con- dyles of the femur, and the synovial membrane of the articulation of the knee ; the outer muscle with the popli- teus ; the inner with the semimembranosus, the popliteal artery, the plantaris and soleus muscles; in the remainder vol. i. 40 306 MUSCULAR SYSTEM of its extent it is in apposition with the soleus. The pos- terior surface is connected with the integuments. ' The separation of the two muscles, at b, a, contributes to form the ham. _,, The office of these muscles is to extend the foot 1 hey are seen very strongly acting in dancing, runnmg leaptng^ and when we are raising onrselves on the toes. From their origin on the femnv, they also have the power of bending the leg on the thigh. OF THE INFERIOR EXTREMITY. 307 SOLEUS. Fig. 173. This muscle is placed under the preceding, but part of it appears on each side of those muscles. Supe- riorly it is attached, by the external portion at a, to the posterior part of the head of the fibula, and to the superior third of the oblique line on the posterior surface of the tibia, and to a portion of the internal border of that bone below f, the popliteus, the fleshy fibres terminating, at b, in a broad aponeurosis ; inferiorly, this aponeurosis is inseparably united with that of c, the gastrocnemii, forming the tendo-Achillis, which is inserted, at g, into the os calcis."1 The posterior surface of the soleus is connected with the gastrocnemii and plantaris, and with the aponeu- rosis of the leg ; the anterior surface with the peroneus longus, popliteus, flexor longus digitorum, flexor longus pollicis, and tibialis posticus muscles, a portion of the back of the fibula, the popliteal, posterior tibial, and fibular vessels. This muscle assists the gastrocnemii in extending the foot and in raising the heel in progression. m From the circumstance of the three muscles being united into one tendon, H.Cloo.uet has described them as a single muscle, under the name of triceps extensor pedis. 308 MUSCULAR SYSTEM PLANTARIS. This muscle, which is long, and extremely thin and nar- row, is situated under the outer portion of the gastrocne- mius. It is attached superiorly, at d, to the posterior part of the external condyle of the femur, and adheres to the capsule of the knee joint, and to the tendon of the gastroc- nemius externus. It forms behind the joint a small fleshy fasciculus, which passes over the popliteus, /, and sends a very long and slender tendon, e, obliquely inwards, which accompanies c, the tendo-Achillis, to be attached with it, at g, to the os calcis. The posterior surface of the plantaris is connected with the gastrocnemii and integuments ; the anterior surface with the ligaments at the posterior part of the knee joint, the popliteal vessels, and the popliteus and soleus muscles. The particular use of this muscle has been a question with physiologists ; although it is generally classed with the extensors of the foot, it is so extremely slender that it can have but little power in the motions of the limb. I am of opinion, that its office is solely to contract the fold- ings of the capsule, so as to prevent injury in the flexion of the knee joint. POPLITEUS. This is a small muscle, Fig. 174, a, Fig. 173, /, of a triangular figure, situated across the back part of the knee joint. It is attached superiorly within the capsule of the knee joint, by a round tendon, to the depression of the external condyle of the femur; it adheres to the posterior and outer surface of the semilunar cartilage ; and at the OF THE INFERIOR EXTREMITY. 309 back part of the condyle it perforates the capsular liga- ment, and forms a fleshy mass, which, passing obliquely inwards, is attached inferiorly, broad, thin, and fleshy, to the superior triangular surface at the back part of the tibia. The posterior surface of the popliteus is connected with the gastrocnemii and plantaris muscles, the popliteal ves- sels, and the posterior tibial nerve ; the anterior surface with the articulation of the tibia and fibula, the tibialis posticus muscle, and the tibia. The outer margin is united above by a thin membrane with the upper part of the fibula and soleus. The office of this muscle is to bend the thigh and the leg; but chiefly, like the preceding, it prevents the capsule from being compressed in the motions of the knee joint. 310 MUSCULAR SYSTEM FLEXOR LONGUS DIGITORUM PEDIS. Fig. 174. This muscle, b, is situated be- neath the soleus; it is attached superiorly to the posterior surface of the tibia, and to the superior f^x^c^^lff oblique line, until it arrives within three inches of the ankle. The fleshy fibres pass obliquely into a tendon at the posterior edge of the muscle; this tendon runs behind the inner ankle in a groove of the tibia, and is secured in this situa- tion by a strong ligament, which is extended from the ankle to the os calcis, and having received a tendinous slip from the flexor lon- gus pollicis, divides about the mid- dle of the sole of the foot into four tendons, which pass through slits in the tendons of the flexor digitorum brevis, and are finally attached to the posterior part of the inferior surface of the last pha- lanx of the four small toes. The posterior surface of this muscle is connected with the so- leus muscle, the tibial aponeurosis, and the posterior tibial artery; the anterior surface with the tibia and the tibialis posticus muscle. The outer border is united with that muscle, and with the flexor proprius pollicis pedis. In the foot, the upper surface is connected with the deep-seated muscles of the sole, and the lower surface of its tendons OF THE INFERIOR EXTREMITY. 311 with the adductor pollicis, flexor brevis digitorum, adduc- tor minimi digiti muscles, and the plantar nerve. The office of this muscle is to bend the last joint of the toes, to extend the foot; and it is of great use in walking and standing. FLEXOR LONGUS POLLICIS PEDIS. This muscle, c, e, is placed on the outer side of the preceding, between that muscle and the peroneus longus. It is attached superiorly by fleshy fibres to the middle part of the back of the fibula, to the interosseous ligament, and the aponeurotic septa; the muscular fibres, c, terminate in a tendon at e, which passes behind the inner ankle; (it is found further back, that is, nearer the os calcis, than the flexor longus digitorum pedis) ; and in the sole of the foot it crosses the tendon of that muscle to be ultimately at- tached at f, the last joint of the great toe. The posterior surface of this muscle is connected with the soleus and aponeurosis of the tibia; the anterior sur- face with the fibula, the tibialis posticus, and the flexor longus communis muscles, the tibia, and the interosseous ligament. Its tendon is enveloped by synovial membranes behind the ankle joint, and under the great toe, and by the flexor brevis pollicis under the sole of the foot. This muscle bends the great toe, and assists in extend- ing the foot on the leg. 312 MUSCULAR SYSTEM TIBIALIS POSTICUS. Fig. 175. The flexor longus digitorum pe- dis, and the flexor longus pollicis pedis, are here removed to show the situation of the tibialis posti- cus ; the muscles which cover the tendon in the sole of the foot also are separated to exhibit its inferior attachment. Superiorly, the tibi- lis posticus is attached to the pos- terior surface of the tibia at c, to the fibula at f to the surface of the interosseous ligament, and to the aponeurotic septa; the fibres pass obliquely, at b, towards a central tendon, which passes behind the inner ankle in a channel of the tibia, and is inferiorly inserted into the internal and inferior part of the os naviculare, sending ten- dinous filaments to the adjacent bones. The anterior surface of the tibi- alis posticus is connected with the tibia and fibula, a large extent of the interosseous ligament, and the inferior part of the os calcis and scaphoides. The posterior surface is covered by the soleus, the flexor longus digitorum, and the flexor proprius pollicis muscles, and by the fibrous sheath of the inner malleolus. This muscle is an extensor of the foot, and it draws it inwards. OF THE INFERIOR EXTREMITY. 313 MUSCLES OF THE FOOT. DORSAL REGION. EXTENSOR BREVIS DIGITORUM PEDIS. Fig. 176. This is a broad flat muscle, situated on the upper part of the foot; the tendons of the long extensor pass over it, but in this figure they are cut off near the toes. Posteriorly, the exten- sor brevis, a, is attached, at c, to the upper surface of the os calcis, the os cuboides, and the astragalus; its fleshy fibres divide at b, b, b, b, into four por- tions, each of which sends off a slender tendon ; one of them is inserted ante- riorly into the first phalanx of the great toe, the others into all the small toes except the little one, and uniting with the tendons of the extensor longus, they invest the upper surface of the phalanges of the toes. The upper surface of the short extensor of the toes is connected with a very thin aponeurotic lamina extended over the back of the foot, and with the tendons of the long extensor of the toes; the inferior surface with the tarsus, the metatarsus, the interossei dorsales muscles, and the phalanges. The office of this muscle is to assist in extending the first four toes, and it directs them a little outwards. INTEROSSEI EXTERNI. These small muscles are similar in form and arrange- ment to those of the hand. They are seen on the back of VOL. I. 41 314 MUSCULAR SYSTEM the foot at b, b, b, b; being attached posteriorly between the metatarsal bones of all the toes; anteriorly, to the first joint of the smaller toes. They are divided into ad- ductors and abductors of the toes. The office of these muscles is to separate the toes. PLANTAR REGION. FLEXOR BREVIS DIGITORUM PEDIS. Fig. 177. This muscle, a, is situated in the middle part of the sole of the foot. Posteriorly it is attached to the infe- rior surface of d, the os calcis, to the inner surface of the plantar aponeu- rosis, and to the tendinous septa interposed between this muscle and the abductors of the toes. It forms a thick fleshy mass, and divides into four tendons, which, having advanced beyond the tarsus, are split for the passage of the long flexor tendons, and are ultimately attached to the inferior surface of the second phalanx of the four lesser toes. The tendon to the little toe, however, is not al- ways found. The inferior surface of the short flexor of the toes is connected with the plantar aponeurosis; the superior sur- face with the lumbricales and accessory muscle of the flexor longus, with the plantar vessels and nerves, and with the tendons of the long flexor. The inner border is united to the adductor pollicis posteriorly, but is separated from it anteriorly by the tendon of the flexor longus and OF THE INFERIOR EXTREMITY. 315 a portion of the flexor brevis of the great toe; the outer border is contiguous anteriorly to the flexor brevis minimi digiti; posteriorly it is annexed to the abductor minimi digiti. This muscle bends the second joint of the toes. ABDUCTOR POLLICIS PEDIS. This muscle, c, is placed at the inner edge of the foot. It is attached posteriorly to the lower and inner part of d, the os calcis, and plantar aponeurosis; anteriorly to the inner sesamoid bone, and base of the first bone of the great toe. The inferior surface of the adductor of the great toe is connected with the flexor communis digitorum pedis, the flexor accessorius, the lumbricales muscles, and the plan- tar aponeurosis ; on the inner border with the flexor brevis pollicis pedis, the tendon of the peroneus longus, and the outer side of the metatarsal bone ; on the outer border with the interosseous muscles and external plantar artery. , The office of this muscle is to carry the great toe from the others. ABDUCTOR MINIMI DIGITI PEDIS. This muscle, b, is situated at the outer edge of the sole of the foot. Posteriorly, it is attached to the outer side of d, the os calcis, to a ligament which passes from that bone to the metatarsal bone of the little toe, and to the plantar aponeurosis ; anteriorly, to the outside of the first bone of the little toe. This muscle carries the little toe outwards and down- wards. 316 MUSCULAR SYSTEM FLEXOR DIGITORUM ACCESSORIUSn. This muscle, a, is situated at the posterior part of the sole of the foot. It is attached on the one part by aponeurotic fibres to the inferior and internal surface of c, the os calcis, from which it proceeds in a horizontal direc- tion ; on the other part it is in- serted into the external border of b, the tendon of the flexor lon- gus digitorum pedis. The inferior surface is con- nected with the adductor pollicis pedis, flexor brevis digitorum pe- dis, adductor minimi digiti pedis, and the plantar vessels and nerves; the superior surface with the os calcis, the superficial inferior ligament of the os calcis and os cuboides, and with the abductor minimi digiti pedis. The office of this muscle is to assist the flexor longus digitorum pedis. LUMBRICALES PEDIS. These muscles, Fig. 178, c, c, c, c, are similar in form and number to the lumbricales of the hand; they are an » Or maisa rarnea Jacobi Sylvii. OF THE INFERIOR EXTREMITY. 317 apparatus of moving powers to assist the flexors of the toes. The lumbricales pedis are situated at the anterior part of the foot, and extend from the tendons of the flexor longus digitorum pedis, to the first phalanx of the four lesser toes. The inferior surfaces of the lumbricales are connected with the plantar aponeurosis ; their superior surfaces with the abductor pollicis pedis, the transversus pedis, and with the plantar interosseous muscles. The office of the lumbricales is to bend the toes, and to draw them a little inwards. FLEXOR BREVIS POLLICIS PEDIS. The fleshy part of this muscle, a, is connected al- most inseparably to the ad- ductor aud abductor pollicis. It is attached posteriorly to the fore part of the os calcis, and to the two cuneiform bones; extending anteriorly to the inferior and lateral part of the first phalanx of the great toe, and to the sesa- moid bones of the articula- tion. The inferior surface of the short flexor of the great toe is connected with the plantar aponeurosis, flexor proprius, and adductor pollicis pedis ; the superior surface with the tendon of the peroneus longus, and with the first metatarsal bone: the outer edge is united to the abductor pollicis. 318 MUSCULAR SYSTEM The office of this muscle is to bend the first joint of the great toe. ADDUCTOR POLLICIS PEDIS. This muscle, b, is placed at the internal part of the sole of the foot. Posteriorly, it is attached by aponeurotic and fleshy fibres, at a, b, in two portions, to a strong ligament, which extends from the os calcis to the os cuboides, and to the plantar aponeurosis; from these different attach- ments it advances to be inserted into the outer sesamoid bone, and the base of the first phalanx of the great toe. The inferior surface of this muscle is connected with the plantar aponeurosis; the superior surface with the flexor accessorius, the flexor brevis pollicis, the tendons of the flexor longus digitorum pedis, the tibialis anticus and posticus, and with the plantar vessels and nerves. This muscle carries the great toe outwards, and bends it a little. FLEXOR BREVIS MINIMI DIGITI PEDIS. This muscle, d, is situated at the outer edge of the sole of the foot. It is attached posteriorly to the metatarsal bone of the little toe, and to the ligamentous sheath of the tendon of the peroneus longus ; anteriorly, it is inserted into the first joint of the little toe. The inferior surface is connected with the plantar apo- neurosis and abductor minimi digiti pedis; the superior surface with the fourth metatarsal bone and last plantar interosseous muscle. The office of this muscle is to assist in the flexion of the little toe. OF THE INFERIOR EXTREMITY. 319 TRANSVERSUS PEDIS. This muscle, e, is situated at the anterior part of the sole of the foot. It is attached on the outer side to the ligaments of the four last articulations of the phalanges of the toes with the metatarsus; on the inner side, to the external border of the first joint of the great toe. The inferior surface of the transversus pedis is con- nected with the tendons of the long and short flexors of the toes, the lumbricales, and the collateral vessels and nerves of the toes; the superior surface with the interos- seous muscles. This muscle carries the great toe outwards, and brings the metatarsal bones nearer to each other. INTEROSSEI INTERNI. These muscles, c, are three in number, and are situated in the sole of the foot. They are attached posteriorly between the metatarsal bones of the four lesser toes ; ante- riorly by tendons to the inside of the first joints of the three smaller toes. * The office of these muscles is to move the three smaller toes towards the greater toe. APONEUROSIS OF THE LEG. This is continuous superiorly with the femoral aponeu- rosis; it adheres strongly to every projecting point of bone, as to the head and spine of the tibia, and to the fibula. At the inferior part of the leg it has very strong adhesions to the outer and inner ankle: it is continuous also with the annular ligament of the instep, and is fixed 320 MUSCULAR SYSTEM on the outer side to the sheath of the tendons of the pero- neal muscles, aad on the inner side to the internal annular ligament. ANNULAR LIGAMENT OF THE INSTEP. This is a transverse band of fibres which binds down the tendons of the extensors of the foot and toes: the anterior part of the annular ligament is attached on the one side to the external part of the os calcis : on the other side to the anterior part of the inner malleolus. It em- braces the tendons of the extensor longus pollicis pedis, the extensor longus digitorum pedis, the peroneus tertius, and the tibialis anticus. The internal annular ligament is broader, extending from the internal malleolus to the os calcis ; it forms with that bone a species of canal, which contains the sheaths of the tendons of the tibialis posticus, the flexor longus digitorum pedis, the flexor longus pollicis pedis, and the plantar vessels and nerves. See Fig. 170, and 171°. o The plantar aponeurosis so much partakes of the nature of a ligament, that I haye thought proper to arrange and describe it with the ligaments. See p. 133. • OBSERVATIONS ON THE MUSCLES. 321 OBSERVATIONS ON THE MUSCLES. In describing the offices of muscles I have confined my observations to their simple motions; but there are very few simple motions in the animal economy: almost every kind of contraction is the effect of a combined effort of several of the muscles. One action produces another: for this reason, the two points by which a muscle is attached have an equal tendency to move; if not prevented by the action of other muscles, both extremes would come into motion when the muscle contracted: thus, by the con- traction of the extensors of the leg, the limb would be bent on the foot equally with the foot on the leg, if the foot was not fixed; but it can only be so fixed by means of muscles acting in a reverse, or opposition to the extensors; therefore, whenever two points of attachment are move- able, the simple motion of the one extreme supposes the contraction of a muscular power to fix the other. No muscles are enabled to move singly without the aid of other muscles, except those which are inserted by one of their extremities into a fixed, and by the other into a moveable point, as those of the eye, and the greatest part of the moving powers of the face. We may remark, how- ever, that there is always an immoveable line or point from which every ordinary motion originates, and one ex- tremity is always more moveable than the other; thus, although the two attachments of the gastrocnemii are moveable, yet these muscles act more effectually upon the foot than upon the femur. To ascertain the office of a muscle, we must examine its direction from the more fixed, up to the more moveable vol. i. 42 322 MUSCULAR SYSTEM. point—the reverse of that direction is the line of action. The tibialis anticus directed downwards and inwards raises the foot and brings it outwards ; the rectus femoris directed from the pelvis towards the patella raises the leg without the least deviation. Every other muscle, whatever may be its attachments, has the same disposition : they always act in the reverse of the line of their direction ; the coraco brachialis, which is directed downwards and outwards from the shoulder towards the arm, moves the latter upwards and inwards. By this rule, when we see a muscle we may decide for what uses it was intended. The whole effort of the contraction in long muscles is usually concentrated on a single point of the tendon : in the greatest part of wide muscles, on the contrary, the insertions being on the sides, and by a number of points, all the fibres have not an uniform action. The different parts of the same muscle may be intended for very differ- ent, and even for opposite uses; thus, the anterior fibres of the deltoides advance the arm, the posterior draw it backward, and the lower part of the serratus major does not act like the upper; frequently, even different portions of the same muscle do not contract simultaneously : the upper portion of the trapezius may act independently of the lower ; the same may be observed of the muscles of deglutition. In the long muscles, however, every fasci- culus concurs to produce the same effect at the same moment. If a wide muscle is concentrated in one common point, as the temporal and deltoid, which is attached to a multi- plicity of points on the one part, and on the other is attached by a single tendon, then the average diiection of all its fibres is to be taken to ascertain its office. If a muscle is attached by many points at each extremity, the line of direction of its fasciculi must be examined to judge of its action. It is in this way we understand the action of OBSERVATIONS ON THE MUSCLES. 323 the rhomboideus, serratus magnus, etc. In those muscles which are reflected, as the obliquus superior of the eye, the circumflexus palati, the peronei, etc., the action of the muscle must be calculated from the point of reflexion only. The orbicular muscles, as those situated round the lips, the eyes, etc., have in general no fixed point: they are intended merely to contract the aperture round which they are situated. Let it again be observed, that with very few exceptions, the actions of muscles are associated. A number of mus- cles are required, even to nod the head, to maintain the body erect, to put it in motion, or to continue it in pro- gression ; and in very great bodily efforts, all the voluntary muscles appear to be in action. In early life, the muscular system appears to be pene- trated with less blood than at a later period, the muscles of the infant being of a much paler colour than those of the adult; as age advances they gradually assume a deeper colour, they receive a greater supply of blood-vessels, and consequently are more abundantly nourished than many other organs. During the period of infancy and youth, the conformation of the male and female muscles is analo- gous. In the former, after growth in stature is completed, the muscles increase in bulk; to the slender and rounded form of adolescence, alternate projections and depressions mark the outline of the more manly form; and we may remark at this period the muscular system appears (if the organs are well exercised) through the integuments, the fleshy masses of muscular fibre forming prominences sepa- rated by distinct grooves. Painters and sculptors pay great attention to the development of the muscles, making them characteristic of the figures they represent under different circumstances and modes of life ; as we may ob- serve in the statues of the Farnese Hercules and Pancra- 324 MUSCULAR SYSTEM. tiastae, contrasted with those of the Antinous and Apollo Belvidere. As the muscles increase in thickness they acquire more density. A remarkable difference may be observed in the firmness of the muscles, especially in a state of contraction, in the adult and in the infant, and between persons who are accustomed to take a great deal of robust exercise and those who are less accustomed to exertion; thus, while the sedentary and indolent are remarkable for the flaccidity of their muscles, the active have them firmly developed. The gymnastic exercises are very much cal- culated to produce this effect, and to strengthen the mov- ing powers; but such exercises should be taken gradually, and youth should not be urged to exertions beyond those which they can accomplish without subsequent painful sensations. In the prime of life, the colour of the muscles is of a deep red; in the subsequent stages of life they gradually fade ; but there are other causes besides advanced age which destroy the brilliancy of their hue, such as ill health, and excesses of any kind, which have a depressing influ- ence on the vital powers. As age advances, the muscles undergo other changes: the fibres become tough and resistant, and their excess of density seems to prevent their contraction ; at least, they can no longer perform with such rapidity as formerly, nor can movements be continued so long, for weariness sooner follows. But though in persons advanced in life the fibres are dense, the general feeling of the muscles is loose and flaccid, and the calves of the legs quiver in walking, as if less capable of action. Old age is a period at which mo- tion causes a tremor of the whole muscular system. Why is this ? Bichat says, it is because the muscles no longer possess a sufficient degree of contractility, and that they OBSERVATIONS ON THE MUSCLES. 325 are thus too long for the spaces which they fill. This appears to proceed from the contractility of the tissue being reduced in the last stage of life. We are convinced of this fact by comparing a muscle divided transversely in a young and in an aged person: in the former it contracts much more than in the latter. By the very great contractility of the muscles of youth, all their fibres are drawn closer together during repose, as well as in action ; but in the progress of age this effect is no longer produced : these organs therefore remain lax and flaccid, a phenomenon which indicates the low state of contractile power. As the blood flows in less quantity to the muscular sys- tem of infants, and increases gradually as persons become of an adult age, so the quantity of blood gradually de- creases as persons become advanced in years; the vessels in old subjects become partially obliterated, and the parts being deprived of their former supply of the vital fluid, are left in the state before described, possessed of a reduced state of vital contractility and sensibility. The condition of the muscular system after death de- pends upon the causes which produced it: in ordinary cases, after a short time the dead body becomes stiff, and retains the form it is placed in until decomposition takes place ; but in some particular cases, as in poisoning and suffocation from the fumes of charcoal, and in several other instances, the muscles never become firm : all contractility is extinct, and the body continues soft and flexible. 326 MUSCULAR SYSTEM. BURS2E MUCOSJE, 0T MUCOUS BagS. The structures we are about to describe not only enter into the composition of joints, but are placed between the tendons and bones exposed to much friction, and therefore may be considered as auxiliaries to the moving powers. The bursa? mucosae are intended for the same purpose as the synovial membranes, viz. to produce or secrete a fluid similar to the synovia, which lubricates contiguous surfaces. Their structure and anatomical arrangement are nearly the same, both being shut sacs. Dr. Monroe discovered and described 140 of them, and since which several other bursa? have been described by Dr. Rosenmuller of Leip- sic; they perform the office of friction-wheels in machi- nery, and take off too severe pressure or friction from the bone or tendon. Bursa? vary considerably in size, as well as in form, some being oval or circular, others elongated, so as to form sheaths which inclose tendons. Thus, where tendons are retained in situ by fibrous sheaths, the conti- guous surfaces are invested by a bursal membrane reflected over them, as the different flexor and extensor tendons in both extremities; and also where a muscle has to slide over a bony prominence, as where the gluteus maximus passes over the great trochanter, a bursa is interposed ; or where processes of bone play on fibrous structures, as be- tween the acromion and the capsule of the shoulder joint. These instances will suffice to point out the operation of the general principle which determines the formation of synovial or mucous bursa?. The following enumeration is from Mr. Bell, and constitute the principal bursa? of the human body. In connection with the shoulder joint : 1st. A very large bursa under the acromion, and betwixt it and the head of the humerus. BURSjE. 327 2nd. Between the head of the clavicle and the coracoid process of the scapula. 3rd. Upon the capsule of the shoulder-joint and under the tendon of the subscapularis muscle. 4th. Under the deltoid muscle. 5th. Under the tendon of the latissimus dorsi. The principal bursa? around the elbow-joint are, 1st. Between the tendon of the biceps flexor cubiti and the radius. 2nd. Over the round head of the radius and the exten- sor muscles. 3rd. On the olecranon and under the triceps tendon. About the wrist, 1st. A large bursa between the flexor tendons and the carpus. 2nd. On the trapezium. 3rd. On the pisiforme. 4th. On the back of the carpus and under the extensor carpi radialis. 5th. Between the ligament of the wrist and the tendqn of the extensor carpi ulnaris. Besides these sacs or proper bursa?, sheaths surround the tendons of almost all the muscles of the wrist-joint. On the pelvis, 1st. A large bursa between the gluteus maximus and the vastus externus. 2nd. Between the capsule of the hip-joint and the psoas magnus and iliacus internus. 3rd. Under the pectinalis. 4th. A large one on the surface of the trochanter major, under the gluteus minimus. 328 MUSCULAR SYSTEM. 5th. On the os ischii and under the origin of the biceps. 6th. Under the tendons of the rotators of the thigh bone. In the thigh, and around the knee-joint, 1st. Under the tendon of the extensors of the leg, and communicating with the knee-joint. 2nd. Under the ligament of the patella. 3rd. Between the insertion of the semimembranosus and the origin of the gastrocnemius. 4th. Over the internal lateral ligament of the knee- joint. 5th. Under the popliteus. Several irregular bursa? are found around those tendons which are inserted into the tibia and fibula. Around the ankle-joint. All the principal tendons which cross the ankle-joint have bursa? under or around them, as the tendon of the tibialis anticus, the extensor proprius, the extensor digi- torum, the peroneus longus and brevis. There is also a proper bursa between the tendo-Achillis and the os calcis; another under the flexor longus pollicis, and also under the flexor longus digitorum and the tibialis posticus. It is necessary for the surgeon to know these bursa?; because, after sprain and injuries, effusion takes place in them, and they present a puffy swelling over the joint not easily understood without the recollection of the natural anatomical structure. ART. V. VASCULAR SYSTEM. CHAP. I. ORGANS OF CIRCULATION. THE HEART AND ITS ENVELOPES THE PERICARDIUM. Fie. 180. VOL. I 330 THE PERICARDIUM. The heart is the central organ of circulation; and the pericardium, b, b, is a membranous bag which incloses the heart, a, and the roots of the arterial and venous trunks which issue from it. It is situated in the lower part of the anterior mediastium, above the aponeurotic centre of the diaphragm. It is connected anteriorly with the pleura, the thymus gland, the sternum, and the cartilages of the sixth and seventh ribs of the left side ; posteriorly with the bronchial tubes, the esophagus, and the descending aorta; laterally with the pleura, e, the phrenic nerves, and the inner surface of the lungs. The pericardium is composed of two membranes, an outer fibrous and an inner serous. The fibrous membrane is intimately united below with the aponeurosis of the diaphragm; it ascends around the heart, embraces it as far as the base, and is continued to a certain distance upon the trunks of the great vessels. The pericardium, therefore, is not perforated by these vessels, but its fibrous lamina forms sheaths for them. The serous membrane is much more extended than the fibrous membrane ; for after lining the inner surface of the pericardium, it entirely covers the heart, and is continued upon the aorta above its first curve; to the right, it is re- flected upon the superior vena cava, to the left upon the pulmonary artery before its bifurcation, and upon the right pulmonary veins immediately after their issuing from the lungs. This serous membrane of the pericardium dips into all the irregularities of the surface of the heart, where it is extremely thin and transparent, and is not easily de- monstrated ; it also adheres intimately to the fibrous mem- brane, but it has very little attachment to the vessels, and can be raised from their surface without difficulty. The inner surface of this membrane is smooth, glisten- ing, everywhere in contact with itself, and is moistened THE BLOOD. 331 with a serous fluid, to prevent ill effects from the heart's motion. The arteries of the pericardium are very small, and are derived from larger arteries in the immediate vicinity. The veins correspond to the arteries, and partly terminate in the vena azygos. There have not yet been any ner- vous filaments traced into its lamina. THE BLOOD. I shall premise a few remarks on the blood, before I proceed to describe the organs which circulate it. The general appearance of human blood is too well known to render it necessary for me to describe it. The blood circulates in the heart, arteries, and veins; the esti- mated quantity is about twenty-eight pounds in an adult. In the veins it is of so deep a colour, that it is generally termed black blood; in the arteries it is of a bright Ver- million colour. In order to render the difference between venous and arterial blood more distinct, Majendie has given the fol- lowing table of them. Venous Blood. Arterial Blood. Colour.....Black red .. Vermillion red. Odour.....Weak .. Strong. Temperature . . . 101- 75° F. .. Near 104° F. Capacity for caloric . 852p .. 839. Specific gravity . . 1051q .. 1049. Coagulation . . . Less rapid .. More rapid. Serum.....More abundant . Less abundant. p Water being one thousand. Dr. J. Davy's Philosophical Transactions, 1815. 1 Water being one thousand. 332 THE BLOOD. The blood is the most important fluid of the body, and most essential to the support of its functions. Many able anatomists and physiologists have considered it as a living fluid; and the arguments of those who maintain its vitality are very strong: I consider, stronger than those who take an opposite view of the question. While hot and in motion in its vessels, the blood remains constantly fluid; when it cools and is at rest, it coagulates and becomes a gelatinous mass, which gradually separates into two parts: the one, the crassamentum or the more solid part, the other, the serum or fluid. The respective relations in the quantity of serum to the crassamentum, and those of the colouring matter to the fibrin, are variable, according to the circumstances of age and the state of the health. The crassamentum forms more than half of the blood ; it is plastic, thick, and in consistence like a strong glu- tinous jelly, which soon putrifies in the air; but dried by a gentle heat, becomes a dark brittle mass. The sur- face of the coagulum, after being exposed in a vessel to atmospheric air, becomes of a florid red colour; but the lower surface contiguous to the vessel is of a deep black; the change of colour on the surface is supposed to be owing to the oxygen of the atmosphere uniting with the blood. The crassamentum is composed of—1st, red glo- bules ; 2nd, fibrin. The red globules are obtained by agitating the crassamentum of the blood in the serum ; when the globules, on examination with a powerful micro- scope, will be found floating in that fluid. According to the observations of Captain Kater and Dr. Young, who measured the red globules of the blood with a micrometer, and thus asrree that the size of them is between -r— and ^ 4000 ^ of an inch in diameter, or, taking the medium, ^ of an inchr. f See also Sir E. Home's paper, Philosophical Transactions, 1819. THE BLOOD. 333 The red matter of the blood is soluble in water; when dried and calcined, it yields a charcoal, which furnishes during its combustion ammonial gas, and gives the hun- dredth part of its weight of ashes, composed of Oxide of iron........55.0 Phosphate of lime, with phosphate of magnesia . 8.5 Pure lime........17.5 Carbonic acid ........ 19.0 The fibrin, separated from the colouring matter, is whitish, insipid, and inodorous; elastic when moist, but brittle when dry. In distillation it gives out a great quan- tity of carbonate of ammonia and carbon, the ashes of which contain phosphate of lime, a little phosphate of mag- nesia, carbonate of lime, and carbonate of soda. A hun- dred parts of fibrin are composed of Carbon 53.360 Oxygen 19.685 Hydrogen . 7.021 Azote 19.934 The serum is a transparent liquid, slightly yellow; its odour and taste resemble the odour and taste of the blood. According to Mr. Brand, the serum is almost pure albu- men, united to soda, which holds it in a liquid state. At a temperature of 158° F. it becomes a solid mass, like the white of an egg, and forms on coagulating numerous small cells, which contain a matter very analogous to mucus. 334 THE BLOOD. According to Dr. Marcet, one thousand grains of the serum of human blood contain9, Water........ Albumen....... Muco-extractive matter .... Muriate of Soda, with some muriate of Potash Subcarbonate of Soda..... Sulphate of Potash..... Phosphates of Lime, Iron, and Magnesia . From different analyses of blood, and as the processes of investigation are perfected, we discover in the blood all the principles, all the elements of the various organs of the body. We are able with confidence to point out its fibrin as the same matter with the muscular fibre; the albumen, that which forms cartilage, and so great a number of mem- branes and tissues; the adipose matter, when combined with osmazome and albumen, constitutes the nervous mass ; the phosphates of lime and magnesia, which constitute a great portion of the bones; the elements of the most re- markable excrementitious substances, as urea and the yellow matter of the bile, the urine, and that which by absorption extends itself into the cellular tissues around contusions1. The blood, therefore, is the common source from which every tissue of the body borrows and chooses its materials according to its degree of sensibility, and appropriates them to itself, and subsequently retains or rejects them. The body derives its nourishment from the blood, which sup- plies the waste that is continually going on in the animal frame; and the reproduction of any part which may have been destroyed, equally depends upon it. The blood, im- , Philosophical Transactions for 1819. These results very nearly coincide with an ana- lysis of Berzelic 5. t See Majendic's Compendium of Thysiology, Art. Blood. 900.00 86.8 4.0 6.6 1.65 0.35 0.60 1000.00 THE HEART. 335 pelled by the heart, is transmitted by the arteries to the most minute part of the body, building up the several structures, and keeping them in a state of repair. The superabundant quantity is returned to the heart by the several veins ; but as a large portion of it is expended in preserving the healthy state of the body, it is necessary that a constant supply should be provided, and this is formed in abundance from both animal and vegetable food. THE HEART. The heart is a hollow muscular organ: its form is an- nexed. It is inclined forwards, downwards, and outwards, and from right to left; its general connections have been pointed out in describing the pericardium. The position 336 THE HEART. of the heart somewhat changes as it follows the motions of the diaphragm in breathing, and its weight draws it in different directions according to the inclination of the body. The anterior surface is turned a little upwards, and presents in its middle a groove passing from left to right obliquely downwards, and in which is lodged the anterior coronary artery and vein in the midst of a considerable quantity of adipose tissue. The posterior surface is nearly horizontal, and rests upon the aponeurotic centre of the diaphragm: it is traversed almost vertically by a channel which receives the posterior coronary artery and vein. The base of the heart is situated behind and to the right, and is separated from the vertebral column by the aorta and the esophagus. There is observed on it an oblique groove, which indicates the junction of the auricles and ventricles. The apex is inclined forwards and to the left, and in the living body is felt beating in the interval of the cartilages of the fifth and sixth ribs. The heart contains four cavities, which are termed its auricles and ventricles. An auricle and a ventricle is placed to the right, and to the left the same disposition is observed. On each side the auricle communicates with the corresponding ventricle. In the right cavities there is found black blood, which has been received from all parts of the body, and which must be submitted incessantly to the action of the air in the lungs; in the left cavities we find red blood, which has been received from the lungs, having already undergone a certain change from the atmos- phere, for the purpose of again circulating through the whole body. THE HEART. 337 RIGHT SIDE OF THE HEART. THE RIGHT AURICLE. Fig. 162. The right auricle is also called the anterior auricle; its situation is obvious in the figure before usu. On the right side it has a loose appendage with denticulated borders, which bearing some resemblance to a dog's ear, the whole cavity has obtained the name of auricle. The parietes of this cavity, Fig. 181, n, are so thin as to be semitranspa- rent ; but in the inner surface at c, Fig. 182, its muscular fasciculi are disposed somewhat like the teeth of a comb, therefore have been named musculi pectinati. Its poste- rior part, b, presents the orifice of the superior vena cava, inclining forwards and downwards ; this is separated from a, d, the orifice of the inferior vena cava, by a projection formed by a thickening of the muscular coat, the tuber- u The venae cavx, the auricle, and its opening into the ventricle, is here laid open. vol. i. 44 338 THE HEART. culum Loweri. The septum of the auricle is seen sepa- rating the right from the left; it is thin, and presents, at e, an oval depression named fossa ovalis, at the circumfer- ence of which the fibres are thicker, forming an elevated ring, called the annulus ovalis. The space occupied in the adult by the fossa ovalis, is, in the foetus, an aperture named the foramen ovale, which sometimes remains open through life, the use of which, before the period of birth, is to transmit the blood of the inferior vena cava directly into the left auricle. The orifice of the inferior vena cava is furnished with a duplicature of the inner membrane, which advances into the cavity of the auricle, and is named the Eustachian valve, marked A, f; its dimensions are more considerable in children, and it becomes gradually oblite- rated with age. The auricle is a reservoir in which the blood is collected during the contraction of the ventricle. THE RIGHT VENTRICLE. The ventricles are the most essential part of the heart ; they constitute the forcing machine of the blood, and there- fore merit the most particular notice. The right ventricle has a triangular pyramidical form, the base of which is turned upwards and backwards, being insensibly lost in the corresponding auricle. Anteriorly and outwardly, the muscular parietes, marked I, are thin and concave; the posterior and inner is formed by a par- tition, which equally belongs to the left ventricle. The thickness of the parietes of the right ventricle is unequal in the different parts of their extent: the inner surface presenting a great number of muscular fasciculi, as g, com- monly designated by the name of carnea columna, which vary very much in size, length, and direction. Their dis- THE HEART. 239 position is irregular, some taking a vertical course from the apex to the base, while the others cross them in all sorts of directions, and form with them a confused network. Some of these fleshy columns are much larger than the others, and their number also varies from three or four to eight or nine. These are attached to some points of the parietes of the ventricle, and extending from the apex to the base, they terminate abruptly, each by several small white tendinous strings, called corda tendinea, which are fixed_mto the points of k, k, the tricuspid valve ; in one part diverging from, at another part uniting with, each other. There are other muscular fasciculi attached to the parietes in the manner of pilasters; they follow every variety of direction, and are interlaced with each other, so as to represent network, leaving between them depressions of different dimensions. The entrance from the right auricle to the right ventri- cle is termed the auriculo-ventricular orifice, which is fur- nished with membranous folds, k, k, termed the tricuspid valve, on account of its being divided into three triangular portions, the form of two of which we see in the figure. One of the surfaces of the valve is turned towards the pa- rietes of the ventricle, the other towards the cavity of the auricle. One of its borders is attached to the circumfer- ence of the orifice, the other is divided into three floating portions, which are held in situ by the corda? tendineae, or tendons of the carnese columnae. This valve is thin and transparent in its whole extent, but becomes thicker at its free edge, for the attachment of the small tendons which I have before described. There is another aperture of a smaller size than the pre- ceding, and leads to the pulmonary artery. 340 THE HEART. COMMENCEMENT OF THE PULMONARY ARTERY. Fig. 183. et, & The office of this artery is to carry the blood into the lungs, to be submitted to the action of the air in respira- tion. The pulmonary artery arises from the left part of the right ventricle; its orifice is surrounded by a callous ring, which indicates the limits of the muscular fibres of the heart; this orifice is moreover furnished internally with three membranous folds, c, c, c, which are named sigmoid or semilunar valves: their semicircular form is seen in this figure. They are adherent to the artery by their convex and inferior border, and present in the middle of the loose margin a small tubercle of a fibro-cartilaginous texture, termed the corpus Arantiiv. These are thin and trans- parent; they are in contact at their extremities, and when let down they completely close the artery, and thus pre- vent the blood which it contains from again entering the ventricle. The pulmonary artery passes obliquely upwards and to » So named from Arantius, who first described them. THE HEART. 341 the left side, crossing the course of the aorta, beneath which it passes, and to which it is united by cellular and adipose tissue. After a course of about two inches, it di- vides near the second dorsal vertebra into two branches, one for each lung. Between these branches we observe a round ligament passing from the pulmonary artery to the arch of the aorta: this apparent ligament is the remains of a tube which is named the ductus arteriosus, and which, in the foetus, as the lungs were impervious, transmitted the blood to the right ventriclew. THE LEFT SIDE OF THE HEART. THE LEFT AURICLE. Fig. 184. This figure represents a section of the left auricle and ventricle. The left auricle is situated at the posterior and left side of the heart; its extent is narrower and longer w The distribution of the pulmonary artery will be noticed in a subsequent section. 342 THE HEART. than the right. It presents at its superior and inner part, at a, an auricular appendage, similar to that of the right auricle, but smaller. The interior surface, or the caviiy of this auricular appendix, contains much fewer musculi pectinati than that of the right appendage. Below is the left auriculo-vcntricular orifice, leading to the left ventri- cle. The right side is smooth, and formed by the auri- cular septum. We may observe that the fossa ovalis is here less distinct than on the right side. The left side is perforated at b, d, by two corresponding pulmonary veins; the orifices are very near each other. Like the right pul- monary at f, e, they are destitute of valves. THE LEFT VENTRICLE. Fig. 185. This ventricle is placed at the posterior part of the left side of the heart. Observe at b, and at i, Fig. 184, the great thickness of the muscular parietes. The interior is THE HEART. 343 furnished with a great number of fleshy columns, termed carnea columna, similar to those of the right ventricle, though less numerous, and more irregularly disposed. There are several larger than others, as at g, directed from the apex of the heart to the base, fixed by one of their extremities to the sides of the ventricle, and terminating in a multitude of very slender diverging tendons, which frequently cross each other, and are attached to the loose edge of e, h, the mitral valve. At the base of the left ventricle the opening into the auricle is marked by a whitish zone, to which is connected a fold of membrane, e, h, called the mitral valve, from its shape being compared to a bishop's mitre. It is divided into two portions, to which the tendons of the carneae columnas are attached. There is another opening on the right side which leads into the aorta, Fig. 185, a, which is furnished at c, c, c, with three semilunar valves, similar to those at the entrance of the pulmonary artery. Above the loose edge of the semilunar valves we observe the orifices of the two coronary arteries of the heart. ORGANIZATION OF THE HEART. The tissue of the heart is formed of muscular fibres in close apposition with each other, taking somewhat of an irregular spiral course from the base to the apex, and there, as it were, dipping in and forming the carneae columnar. The parietes of the auricles are much thinner than those of the ventricles. In the right auricle the muscular tissue constitutes a stratum of longitudinal fibres towards the point of union of the two vena? cava?, where it is separated from the serous lamina of the pericardium by a consider- able quantity of fat. In the left auricle the muscular stra- tum is much thicker and more uniform than in the right; the muscular fibres extend from the pulmonary veins to 344 THE HEART. the auricle, where they form a transverse plane; but more deeply they cross each other in a very irregular manner. The exact arrangement of the muscular fibres of the heart is extremely difficult to determine; they intermingle with each other without any apparent cellular tissue being interposed; Cowper, and subsequently J. Cloqjjet, re- present them as disposed in a spiral direction ; but I have frequently examined their fibres, which seem to commence at all points, and extend in all directions; indeed, Ma- jendie confesses that he found it impossible to unravel them. The septum auriculorum forms a thicker and more uni- form layer ; the muscular fibres of the right ventricle are interwoven at acute angles with those of the left; with a degree of patience, however, they may be separated, so as to divide the heart into two portions, the one the right, the other the left. The membrane of the cavities of the heart is evidently continuous with the membranes which line the vessels des- tined for the circulation of the blood. On the right side the inner coat of the vena? cava? is extended to the auricle, upon the muscular fasciculi, and in their intervals upon the serous tissue which covers the heart. Beneath the infe- rior vena cava it is folded upon itself, to form the Eusta- chian valve. Again, at the circumference of the auriculo- vcntricular orifice, it is separated from the muscular tissue by a thin layer of fat, which constitutes the white circle we have before mentioned. There also it is folded, as it were, on itself, leaving the parietes of the heart to form the tricuspid valve ; after which we may trace it through the whole ventricle and into the pulmonary artery, form- ing by its folding the three semilunar valves, and continued to the most minute ramifications of that vessel. THE HEART. 345 The membrane of the left cavities of the heart forms part of the inner tunic of the vessels that carry red blood; it extends from the extremities of the pulmonary veins to the whole cavity of the auricle, and penetrates into the ventricle. At the entrance of the latter its thickness in- creases, and it is so prolonged and doubled on itself, as to form the mitral valve ; we may then view this membrane if we examine the aorta forming the semilunar valves, and extending itself into it, and constituting a lining to all the vessels of the arterial system. THE VESSELS OF THE HEART. There are two arteries which rise immediately from the aorta, and are called coronary; these terminate in veins which have the same name, discharging themselves into the right auricle; its lymphatics "are very numerous, and pass before the aorta and left bronchus. The nerves also which come from the cardiac ganglion are very thickly distributed upon the heart. We must consider a portion of the pericardium likewise as contributing to the structure of the heart, for its whole exterior is invested with it. vol. I. 15 346 THE HEART. Fig. 186. GENERAL OBSERVATIONS ON THE HEARTW. The office of the heart is to force the blood, through the vessels which are connected with it, to the remotest parts of the body, and the same force returns it to the heart by means of the veins ; thus the blood is incessantly flowing from the heart, and again proceeding to it, through the whole period of life, in one circuitous, continual, and inter- minable stream, hence called the circulation. Having studied the heart, we are now prepared to understand its duplex structure and functions, i.e. there is an auricle and a ventricle on the right side, and similar cavities on the left side: the right performs the less, or pulmonic circu- lation ; the left, the great, or systematic circulation. But w The weight of this organ is about ten ounces in an adult, or, as compared to the body, as 1 to 200. THE HEART. 347 to give a more detailed account of the process: 1st, the descending vena cava, q, conveys the blood from the head and upper extremities, the ascending vena cavax, o, col- lects all the blood from the lower part of the body ; they meet and form the right auricle, n. We may term this the first cavity of the heart; its contractions carries the blood into the right ventricle, b, which is stimulated by the quantity and'quality of the blood, contracts, and forces the blood through the lungs by means of the pulmonary artery, k, which divides into right and left, to convey the blood by the branches I, I, which are distributed through all the cells of the lungs, to render it fit for the general circulation. 2nd, The veins of the lungs, m, m, are sometimes three, at other times four, in number: they return the blood, which has been purified in the lungs, to the left auricle, r; this cavity contracts and fills the left ventricle, a, and the muscular action of this ventricle at each beat propels all the blood of the body, communicating its vibrations to the extremest vessels. The blood thus distributed by the large trunks, namely, the aorta, c, e, f, the arteria inno- minata, g, the subclavian artery, h, and the left carotid artery, i, to the smaller branches, is brought back by the veins which are continued from their extremities; this is a fact proved by the veins being filled when a fluid is injected into the arteries. The circulation of the blood also may be seen in the pellucid parts of animals by the aid of a microscope. i p, Veins from the liver, spleen, and bowels. TABLE OF THE ARTERIES. I. PULMONARY ARTERY II. AORTA. ARTERIES FURNISHED BY THE AORTA AT ITS ORIGIN. I. ANTERIOR AND POSTERIOR CORONARY. II. ARTERIES FURNISHED BY THE ARCH OF THE AORTA. Primitive carotid. Divided into external and internal carotids. External carotid. 7. Temporal artery. Furnishes 1. Superior thyroid. 2. Lingual, which 3. External maxillary, or facial, furnishes 8. Internal maxillary artery " gives the dorsal and two sublingual. 1. the inferior pala- tine. 2. submental. 3. coronary arteries of the lips. . /-* • -^ i t_- u (gives the posterior 4. Occipital, which J *mstoid. 5. Posterior auricular, C fae st lo.mastoid. which furnishes ( J 6. Inferior pharyngeal. The external carotid terminates in dividing into the temporal and internal maxillary. Furnishes, 1. The transverse artery of the face. 2 The anterior auricular. 3. The middle temporal. Furnishes thirteen branches, 1. Middle meningeal. 2. Inferior dental. 3. Deep posterior temporal. 4. Masseteric. 5. Pterygoidean. 6 Buccal. 7. Anterior deep temporal. 8. Alveolar. 9. Infra-orbital. 10. Vidian. 11. Superior pharyngeal. 12. Superior palatine. ^13. Spheno-palatine. TABLE OF THE ARTERIES. 349 Internal carotid. Subclavian artery. Axillary artery. Brachial artery. Furnishes, 1. Ophthalmic,which ■> gives 2. The communicating artery of Willis. 3. Choroid artery. 4. Anterior cerebral. 5. Middle cerebral. "I. The lachrymal. 2. Central artery of the retina. 3. Supra-orbital. 4. Posterior ciliary. 5. Long ciliary. 6. Superior and in- ferior muscular. 7. Posterior and an- terior ethmoidal. 8. Superior and in- ferior palpebral. 9. Nasal. 10. Frontal. Furnishes, 1. The verte- bral, which gives fl. The anteri- or and poste- rior spinal. 2. Inferior ce- rcbellic. 3. The basilar, divided into 1. The su- perior ce- rebellic. 2. The pos- terior ce- rebral. 2. Inferior thyroid, which gives the ascend- ing cervical. 3. Internal mammary, which gives 1. The anterior mediastinal. 2. Superior dia- phragmatic. 3. Superior intercostal. 4. Transverse cervical. 5. Superior scapular. 6. Deep cervical. Continuing its course, the subclavian takes the name of axillary. Furnishes, '1. Acromial. 2. Superior thoracic. 3. Inferior thoracic, or external mammary. 4. Inferior scapular. 5. Posterior circumflex. 6. Anterior circumflex. In continuing it takes the name of brachial. Furnishes, 1. Deep humeral or external collateral. 2. Internal collateral. It divides afterwards into the radial and ulnar. 350 TABLE OF THE ARTERIES. 1. Radial artery. 2. Ulnar artery. Furnishes, 1. The radial recurrent. 2. Dorsal artery of the carpus. 3. Dorsal artery of the metacarpus. 4. Dorsal arterj of the thumb, and terminates in forming the deep palmar arch. Furnishes, 1. The anterior and posterior ulnar recurrent. 2. The anterior and posterior interosseous, which furnishes the posterior radial recur- rent. It terminates in forming the super- ficial palmar arch, which gives the colla- teral arteries of the fingers. ARTERIES FURNISHED BY THE AORTA IN THE THORAX. 1. The right and left bronchial. 2. Esophageal, (four, five, or six in number.) 3. Posterior mediastinal. 4. Inferior intercostals, (eight, nine, or ten in number.) ARTERIES FURNISHED BY THE AORTA IN THE ABDOMEN. 1. Inferior right and left diaphragmatic arteries. Divided into three branches. 1. Coronai)- of the stomach. 2. Coeliac artery. 2. The Hepatic, which gives 3. The Splenic, which gives ' 1. The pjloric. 12. The gastro-epiploica | dextra. .3. The cystic. 1. The gastro-epiploica sinistra. 2. The vasa brevia. 3. Superior mesenteric ar- tery. 4. Inferior mesenteric ar- tery. Furnishes from its concavity, "1. The superior, middle, and inferior right co- lie. 2. From fifteen to twenty intestinal branches. Furnishes, '1. The superior. 12. The middle. 13. The left cholic; and divides into the su- perior hainorroidal arteries. 5. The middle capsular arteries (two on either side). 6. Renal or emulgent. 7. Spermatic. 8. Lumbar (four or five on cither side). TABLE OF THE ARTERIES. 351 ARTERIES RESULTING FROM THE BIFURCATION OF THE AORTA. The aorta furnishes a little before its bifurcation, Internal iliac artery. External iliac artery. Femoral artery. Popliteal artery. 1. The middle sacral, I and divides into the I primitive iliacs, which are divided into Furnishes 1. The ilio-lumbar. 2. Lateral sacral. 3. Gluteal. 4. Umbilical. 5. Vesical. 6. Obturator. 7. Middle haemorroidal. 1. The internal. 2. The external iliac artery. 8. Uterine. 9. Vaginal. 10. Ischiatic. 11. Internal pudic, which gives ri. 15, Inferior hasmorroi- dal. Artery of the sep- tum scroti. Transversus peri- nei. Artery of the cor- pus cavernosum. Dorsalis penis. Furnishes 1. The epigastric. 12. Circumflexa ilii, and continues downwards under the name of the femoral artery. Furnishes 1. External epigastric. 2. External superficial & deeply seated pudics 3. Profunda, which gives In continuing its ^ course it takes the name of popliteal. '1. The external and internal circumflex. 2. The superior mid- dle and inferior per- forating arteries. Furnishes 1. The superior middle, external and inter- nal articular arteries. 2. The inferior internal and external arteries. 3. The anterior tibial; its continuation is called the dorsal ar- ■ tery of the foot, which furnishes The popliteal is divided into the peroneal and posterior tibial arte- ries. fl. Tarsal. 2. Metatarsal. 3. Interosseous. 4. Dorsal arteries of the great toe. 352 TABLE OF THE ARTERIES. 1. Peroneal artery. 2. Posterior tibial artery. C Divided into the anterior and posterior I fibular. 'Divided into internal and external plan- tar. It forms, in anastomosing with the continuation of the anterior tibial, the plantar arch, from which the superior, posterior, inferior, and anterior branches are given off". THE ARTERIES. 353 OF THE ARTERIES IN GENERAL. The arteries are those lubes by which the blood is dis- tributed to every part of the body. During life they may be distinguished by their pulsation ; and if wounded, by the florid colour of the blood, and by its escaping per saltum, or by jets ; after death they may be distinguished by their thick whitish coats, which are elastic, for if cut through they preserve a circular orifice ; and lastly, by their having no valves except at their union with the heart. We have taken a review of the heart, which represents a root, the arteries forming, as it were, two highly ramified trees, of which the principal trunk is the aorta, commenc- ing at the left ventricle of the heart, branching out through all parts of the system, aud terminating in minute twigs at the circumference of the body, limbs, and internal or- gans. The other arterial trunk arises from the right ven- tricle, and is extended through the lungs. The arteries very frequently communicate with each other, so that the blood can pass from the one to the other; sometimes such communication takes place between trunks of an equal size, as in the vertebral arteries, which unite to form the basilar ; more frequently a small twig joins a more voluminous trunk, or a transverse branch unites two separate trunks, as in the anterior cerebral arteries; or lastly, two trunks by their union form an arch, as we ob- serve in the mesenteric arteries*. As the arteries are further removed from the heart, their communications are more numerous. In the ultimate branches their union is so exceedingly multiplied as to form an intricate network, ramifying ad, infinitum, and from which the veins and exhalents seem to originate. y The communication of arteries with each other is termed inosculation, or anastomoses, vol. i. 46 354 VASCULAR SYSTEM STRUCTURE OF ARTERIES. The arteries are composed of three membranes or coats, embracing each other; the inner membrane is similar and contiguous with that which lines the heart, being very smooth, thin, and transparent, and so fine as to have no traces of fibres. The outer membrane is dense and com- pact, and seems to be continuous with the surrounding cellular tissue, and which is formed of its compressed laminae; it is called the cellular coat. Between these two coats is a third membrane, which chiefly forms the artery ; it is of a firm, close texture, and strong in proportion to the calibre of the vessel, of a yellowish or grey colour, composed of distinct fibres adherent to each other, and disposed in concentric layers, intimately united to the external or cellular coat, but being very little adherent to the inner membrane. This tissue many anatomists have denominated the muscular coat; but it differs very mate- rially from muscular structure. It is of a peculiar nature, very dense, possessing little extensibility, although it is elastic and contractile. The arteries receive minute arteries, (vasa vasorum,) which enter into the coats of the artery, and form very complicated meshes on the surface, and which pass into venules, terminating in the trunks of the neighbouring veins2. No lymphatics have been traced into them ; but their nerves are very apparent, and are supplied chiefly from the system of the ganglia. i The blood which flows through the artery is incapable of supplying nourishment to it; these small vessels support its vitality, and are not supplied by the artery which they nourish, but by others in the vicinity. OF THE ARTERIES. 355 THE AORTA. The aorta commences at the left ventricle ; it is con- nected with the heart by a continuation of the lining mem- brane of that cavity, prolonged into its interior, and there forming three semilunar valves : see Fig. 185. At its origin, the aorta is concealed by the pulmonary artery, but which at a short distance leaves it, as the aorta immediately is directed upwards and to the right, and crossing before the vertebral column forms a curve called the arch of the aorta, see Fig. 180, c: opposite the third or fourth vertebra it emerges from the pericardium, and occupies the middle of the vertebral column ; it is then directed a little backwards and to the left; from this situ- ation the aorta becomes vertical, and descends in the pos- terior mediastinum upon the anterior and left part of the dorsal vertebrae ; it arrives at the diaphragm, see Fig. 130, n, and passes along with the thoracic duct between its two pillars, f e, d, c, and terminates in the abdomen by di- viding at the fourth or fifth lumbar vertebraa. From its origin to its curve it is termed the ascending aorta, and from the arch to its division it is called the descending aorta, which is again distinguished into the thoracic aorta and the abdominal aorta. The aorta in the pericardium, see Fig. 181, e, is em- braced by the pulmonary artery, k, on the right, and by the vena cava, q, on the left; anteriorly, the mediastinum separates it from the sternum. Its arch lies at first on the trachea, a little before the division of the latter, and after- wards on the bodies of the second and third dorsal ver- tebrae. In the posterior mediastinum it lies on the left of the vertebral column, the esophagus, the thoracic duct, and the vena azygos. a See Fig. 199. 356 VASCULAR SYSTEM THE ARTERIES WHICH THE AORTA GIVES OFF AT ITS ORIGIN. THE RIGHT CORONARY ARTERY. This artery commences from the aorta immediately above the loose edge of the semilunar valves; and is seen in the groove which separates the right auricle from the corre- sponding ventricle. It winds round the channel upon the posterior surface of the heart, where it divides into two branches, which are distributed over the heart and ex- tended to the apex. At its commencement the right coronary artery gives off very small ramifications to the aorta and right auricle ; others extend over the venae cavae and the interarticular septum ; other branches descend upon the right ventricle, and communicate with the left coronary artery. THE LEFT CORONARY ARTERY. The left coronary artery is smaller than the right; it arises like it from the commencement of the aorta, to the left of the pulmonary artery. It then directs itself down- wards between the pulmonary artery and the left auricle, and enters the groove of the anterior surface of the heart, (see Fig. 181, s,) and runs along its whole extent to the apex. It sends branches to the aorta and the pulmonary artery, and to the auricle and ventricle ; and dividing into very numerous twigs it communicates with the branches of the preceding artery. THE ARTERIES OF THE ARCH OF THE AORTA. There are three arterial trunks arising from the arch of the aorta, destined for the head and the superior extremi- OF THE ARTERIES. 357 ties; they are shown in Fig. 186, and designated the arte- ria innominata, g, the left carotid, h, and the left subcla- vian artery, i. ARTERIA INNOMINATA. This artery ascends obliquely to the right, on the side of the trachea, and after the course of an inch divides into two trunks, of which the one is the right carotid, the other the right subclavian artery. PRIMITIVE CAROTID ARTERIES. Fig. 187. 358 VASCULAR SYSTEM It has been already mentioned, that the right carotid artery arises from the arteria innominata, while the left takes its origin from the aorta. But their volume is pre- cisely the same ; they ascend obliquely on each side of the neck, a, to the upper part of the larynx, b, where they divide into two branches, the external and the internal carotid artery. The interval between these two arteries is occupied by the larynx, the trachea, and the esophagus. Anteriorly, the left carotid is connected with the left subclavian vein, the thymus gland, and the clavicle. Pos- teriorly, the common carotids are situated upon the ver- tebral column, and more immediately upon the inferior thyroid arteries, the longi colli, and the recti capitis antici majores muscles. Internally, they correspond to the tra- chea, the thyroid gland, the larynx, and the pharynx. Externally, they are connected with the internal jugular vein, the pneumo-gastric nerves, and the communicating cords of the middle and superior cervical ganglia. EXTERNAL CAROTID ARTERY. This artery, n, extends from the upper part of the larynx to the neck of the condyle of the lower jaw, and is particularly destined for the face and the exterior of the skull. It passes behind the posterior portion of the digas- tric and the stylo-hyoid muscles, where it crosses its direc- tion, winding outwards and backwards, between the zygo- matic process of the temporal bone and the angle of the under jaw ; then divides into two branches, which are named the temporal and internal maxillary arteries. On the outer side, inferiorly, the external carotid is connected with the platysma myoides and integuments, afterwards with the hypo-glossal nerve, the digastricus, and the stylo-hyoid muscles ; and lastly, it is covered by the OF THE ARTERIES. 359 parotid gland. On the inner side, and from below upwards, it is connected with the internal carotid artery, the stylo- pharyngeus, and the stylo-glossus muscles, and the styloid process of the temporal bone. The branches which this artery furnishes are—1st, an- teriorly, the superior thyroid, the external maxillary, and the lingual; 2nd, posteriorly, the occipital and auricular; 3rd, on the inner side, the inferior pharyngeal, and those by which it terminates; the temporal and the internal maxillary arteries. ANTERIOR BRANCHES OF THE EXTERNAL CAROTID ARTERY. I. SUPERIOR THYROID ARTERY. This artery is situated at the fore and upper part of the neck; it extends from the external carotid, a, to the la- rynx, b, and to the thyroid gland, p, where it divides into three branches, which are distributed by a great number of divisions in the parenchema of this organ. On the outer side it is connected with the platysma myoides, the omo-hyoides, and the thyroid cartilage, to which it gives small ramifications, namely, the laryngeal, which is directed towards the upper part of the larynx, passing between the os hyoides and the thyroid cartilage into the larynx, to supply the epiglottis, the muscles, and the mucous membrane of that organ. The crico-thyroid branch is smaller than the preceding, and descends obliquely over the thyroid cartilage, furnishing ramifications to the adjacent parts. II. EXTERNAL MAXILLARY ARTERYb. This artery commences at the anterior part of the exter- b Facial or labial artery. 360 VASCULAR SYSTEM nal carotid above the lingual, e; it proceeds transversely inwards and forwards, and after describing several curves, gains the internal part of the angle of the lower jaw ; passes between the submaxillary gland and the base of the jaw; then ascends towards the angle of the lips ; enters under the union of the levator anguli oris and triangularis mus- cles, and terminates upon the side of the nose as far as the inner angle of the eye, communicating freely with the na- sal twig of the ophthalmic and the infra-orbitar arteries. BRANCHES OF THE EXTERNAL MAXILLARY ARTERY. There is beneath the inferior maxilla, 1st, the inferior palatine, which, after arising near the origin of the inferior maxillary artery, supplies the superior and lateral part of the pharynx, passes between the pillars of the velum pa- lati, and is distributed to the pharynx, the tonsils, and the Eustachian tube, communicating with the superior palatine. 2nd, the submental, which supplies the mylo-hyoideus and the digastricus, and ramifying above the chin, sends bran- ches to the muscles of the superior hyoid region, the sub- maxillary gland, the internal pterygoid muscle, and the mucous membrane of the mouth. On the face the external maxillary artery furnishes external and internal branches, which are distributed to this region. 3rd, the coronary arteries of the lips, which proceed in a serpentine direc- tion on the border of the lips, and communicate with each other at the angles of the mouth. 4th, the dorsal artery of the nose, which supplies the muscles, cartilages, and integuments of this part, and is in general the termination of the maxillary artery. III. THE LINGUAL ARTERY. This vessel commences at the anterior part of the ex- OF THE ARTERIES. 361 ternal carotid between the two preceding arteries, passing inwards and forwards; it is directed a little upwards, and enters between the hyo-glossus and the genio-glossus as far as the root of the tongue, proceeding horizontally along its base under the name of the ranine artery. The lingual artery sends branches beneath the hyo-glossus muscle, and to the middle constrictor of the pharynx, the thyro-hyoi- deus, and the digastricus. From the same point the dor- sal artery of the tongue arises, ramifying in the back of the tongue, the tonsils, and the velum palati. Several twigs from the lingual artery penetrate the genio-glossus muscle ; and one considerable branch, named the sublin- gual artery, passes forwards above the sublingual gland, furnishing branches to those parts, to the mucous membrane of the mouth, and to the adjacent muscles. Lastly, the lingual artery supplies many branches under the tongue, which ramify in the substance of this organ ; at the tip, and above the frenum of the tongue, the two lingual, which have gained the name of the ranine arteries, anastomose with each other. POSTERIOR BRANCHES OF THE EXTERNAL CAROTID ARTERY. / IV. OCCIPITAL ARTERY. This artery, f commences at the posterior part of the external carotid under the parotid gland ; passes obliquely backwards, beneath the posterior portion of the digastricus ; ascends between the transverse process of the atlas and the mastoid process of the temporal bone, and finally ter- minates in a tortuous manner upon the back part of the head. The occipital artery furnishes superior, posterior, and inferior branches, which supply the muscles in that region. One of them, which is larger than the others, is vol. i. 47 362 VASCULAR SYSTEM named the posterior mastoid artery, from traversing the mastoid foramen, and is subsequently lost on the dura mater; others descend in the substance of the muscles on the lateral part of the neck. The extreme branches are more superficial, and lose themselves in the muscles of the posterior region of the neck. V. THE POSTERIOR AURICULAR ARTERY. This is one of the smallest branches of the external carotid ; it passes between the auditory canal and the mas- toid process, and gaining the inferior part of the external ear, divides into two branches, which are distributed to the posterior auricular and temporal muscles, and the integu- ments. But before its division, it furnishes the stylo-mas- toid artery, which enters the foramen of the same name, passes through the aqueduct of Fallopius, and supplies the mucous membrane of the tympanum, the semicircular ca- nals, etc. VI. INTERNAL BRANCH OF THE EXTERNAL CAROTID AR- TERY, OR INFERIOR PHARYNGEAL ARTERY. This artery passes vertically along the lateral and poste- rior part of the pharynx, between the external and internal carotids, and divides into two branches, namely, the pha- ryngeal, which is distributed to the constrictor muscles of the pharynx, and the meningeal branch, which passes between the internal carotid artery and the internal jugular vein, and entering the foramen lacerum posticus, is distri- buted to the dura mater. OF THE ARTERIES. 363 BRANCHES WHICH TERMINATE THE EXTERNAL CAROTID ARTERY. VII. TEMPORAL ARTERY. The temporal artery, k, separates from the internal maxillary artery opposite the neck of the condyle of the jaw, and passes obliquely upwards beneath the parotid gland ; it passes over the zygomatic arch, and glides in a tortuous manner under the anterior and the superior mus- cles of the ear, and becomes subcutaneous, dividing into three branches, namely, the transverse artery of the face, I, which ramifies on Steno's duct and the muscles about this region. The anterior auricular artery, which supplies the external ear. The middle temporal, which pierces the temporal aponeurosis near the zygomatic arch, and is lost in the temporal muscle. Ultimately, the temporal artery divides into the anterior and posterior branches, which diffuse themselves over the occipito-frontalis mus- cle and the pericranium. 364 VASCULAR SYSTEM VIII. INTERNAL MAXILLARY ARTERY. Fig. 1^. This artery is larger than the temporal ; it commences at the external carotid about the same point, and is re- markable for the great number of important branches which it supplies to the deep parts of the face. In this figure the temporal zygoma and the ramus of the jaw is removed, to shew its course between the pterygoid muscles to the floor of the orbit, and spheno-maxillary fossa. OF THE ARTERIES. 365 BRANCHES OF THE INTERNAL MAXILLARY ARTERY BE- HIND THE NECK OF THE CONDYLE OF THE JAW. I. MIDDLE MENINGEAL ARTERY. This is the largest branch, a, of the internal maxillary artery; it mounts almost vertically between the two ptery- goid muscles, and passes into the cranium by the foramen sphinosum of the sphenoid bone. It furnishes branches to the dura mater, the fifth pair of nerves, and to the aque- duct of Fallopius, and then divides into the anterior and posterior branches; the former is found in a deep groove of the parietal bone, and supplies the exterior surface of the dura mater; the latter is distributed to the posterior part of that membrane. The ultimate ramifications of the meningeal artery com- municate with those of the opposite side of the dura mater. II. INFERIOR DENTAL, OR INFERIOR MAXILLARY ARTERY. This vessel descends anteriorly along the inner surface of the ramus of the lower jaw, at the outer side of the pte- rygoideus internus, enters the inferior dental canal, and emerges by the mental foramen. Before entering the dental canal it supplies the pterygoid muscle ; in the canal it furnishes the teeth with branches, which pass through the foramina at their roots. One of its branches passes out of the mental foramen, is distributed to the triangularis and quadratus muscles, at b, and communicates with the facial artery ; another branch continues its course to the chin, and gives twigs to the canine and incisor teeth. 366 VASCULAR SYSTEM BRANCHES OF THE INTERNAL MAXILLARY BETWEEN THE PTERYGOID MUSCLES. I. POSTERIOR DEEP TEMPORAL BRANCH. This artery, c, ascends between the temporal and exter- nal pterygoid muscles, and is distributed to the temporal muscle and periosteum in the temporal fossa. II. MASSETERIC ARTERY. This branch passes between the temporal muscle and the neck of the condyle of the lower jaw, and ramifies in the masseter muscle, communicating with the transverse artery of the face. III. PTERYGOID ARTERIES. These arteries, d, are distributed to the pterygoid mus- cles. BRANCHES OF THE INTERNAL MAXILLARY ARTERY IN THE ZYGOMATIC FOSSA. I. BUCCAL ARTERY. This artery, i, descends, then advances between the in- ternal pterygoid muscle and ramus of the inferior maxilla, supplying the buccinator and the zygomaticus major mus- cles, and the mucous mercibrane of the mouth. IT. ANTERIOR DEEP TEMPORAL ARTERY. This artery, /, ascends into the anterior part of the tem- poral fossa, and is lost in the temporal muscle. OF THE ARTERIES. 367 III. ALVEOLAR ARTERY. This artery descends on the maxillary tuberosity, and sends branches into the superior and posterior dental ca- nals, to supply the molar teeth and the membrane of the maxillary sinuses. IV. INFRA-ORBITAR ARTERY. This artery, e, commences from the maxillary at the anterior superior part of the zygomatic fossa, enters the infra-orbitar canal, and emerging from it, communicates freely with the facial, alveolar, buccal, and ophthalmic arteries. BRANCHES OF THE INTERNAL MAXILLARY ARTERY IN THE SPHENO-MAXILLARY FOSSA. I. VIDIAN OR PTERYGOID ARTERY. This is a very slender artery penetrating the pterygoid canal, and passing out is distributed to the Eustachian tube. II. SUPERIOR PHARYNGEAL ARTERY. This artery passes obliquely backwards, and entering the pterygo-palatine canal, terminates at the pharynx. III. SUPERIOR PALATINE ARTERY. This artery is larger than the two last mentioned, and proceeds vertically into the pterygo-maxillary fissure, after- wards into the posterior palatine canal, and passing out is reflected forwards to supply the mucous membrane of the palatine arch. 368 VASCULAR SYSTEM IV. SPHENO-PALATINE ARTERY. This may be considered as the ultimate distribution of the internal maxillary artery, which, passing into the spheno-palatine foramen, supplies the nasal fossa, the max- illary, the sphenoidal, and the frontal sinuses. INTERNAL CAROTID ARTERY. The internal carotid separates from the external behind the digastric muscle, mounts between the anterior and lateral part of the vertebrae of the neck and the pharynx, and then enters the carotid canal. After emerging from this canal it passes upwards and forwards, penetrates the cavernous sinus of the dura mater, and making two inflec- tions, like the curves of a Roman S, arrives beneath the anterior clinoid process; here it ascends obliquely back- wards, pierces the dura mater, and terminates in very many branches. While the internal carotid is in the ca- vernous sinus, it sends two or three twigs to the dura mater, the pituitary body, the membrane of the sphenoidal sinus, and to the nerves of the orbit. OF THE ARTERIES. 369 OPHTHALMIC ARTERY. Fig. 189. This artery enters the orbit, traversing the optic fora- men with the nerve/, of the same name, on the outer side of which it is situated ; afterwards it crosses above it, being covered by the rectus superior of the eye, g, and proceeds horizontally along the internal wall of the orbit as far as the internal canthus, where it terminates in sending off the following branches: I. THE LACHRYMAL ARTERY. This artery arises from the ophthalmic immediately after its entry into the orbit, passes outwards between the exter- nal side of this cavity and external rectus muscle, as far as the lachrymal gland, c, where it ramifies, and supplies the muscles in this region, as also the muscles of the supe- rior and inferior eyelid. II. THE CENTRAL ARTERY OF THE RETINA. This artery is exceedingly slender; it obliquely perfo- vol. i. 48 370 VASCULAR SYSTEM rates the coverings of the optic nerve, reaches its centre, and passes into the eye, where it sends a great number of branches to the inner surface of the retina, as far as the corpus ciliare; one of its branches penetrates the vitreous humour, and may be traced, when injected with mercury, to the posterior part of the capsule of the chrystaline lens. ARTERIES SENT OFF BY THE OPHTHALMIC ABOVE THE OPTIC NERVE. III. THE SUPRA-ORBITAR ARTERY. This artery passes forwards along the superior wall of the orbit, and makes its exit by the supra-orbitary foramen, where it divides into an internal and an external branch, the former supplying the muscles in that region, the latter extending to the integuments of the forehead. IV. THE POSTERIOR CILIARY ARTERIES. These arteries are very numerous, generally thirty or forty; they communicate with each other round the optic nerve, and traverse the sclerotica. The greater number, however, of these arteries, pass between the sclerotic and choroid coats, and are distributed to the external surface of the latter, forming a very delicate network. V. THE LONG CILIARY ARTERIES. These arteries are two in number, one on the inner side, the other on the outer; they penetrate the sclerotica, pass forwards between this coat and the choroid, and arriving at the ciliary circle, form by their anastomoses a network on the great circumference of the iris. From the inner OF THE ARTERIES. 371 part of this arterial circle other smaller branches proceed, and form a second circle within the former; and these again form a third circle of vessels of greater tenuity, which immediately surrounds the pupil. VI. THE SUPERIOR AND INFERIOR MUSCULAR ARTERIES. These arteries are distributed to the superior and infe- rior muscles of the eye, to the periosteum of the orbit, and to the lachrymal sac. ARTERIES SENT OFF BY THE OPHTHALMIC IN ITS COURSE ALONG THE INSIDE OF THE OPTIC NERVE. VII. THE POSTERIOR AND ANTERIOR ETHMOIDAL ARTERIES. These arteries are directed towards the internal part of the orbit, traverse the posterior internal orbitar canal, and are lost on the dura mater within the cranium. VIII. THE SUPERIOR AND INFERIOR PALPEBRAL ARTERIES. These arteries supply the anterior parts of the orbit, the caruncula lachrymalis, the lachrymal sac, and the eyelids, and communicate with the lachrymal artery. BRANCHES WHICH TERMINATE THE OPHTHALMIC ARTERY. IX. THE NASAL ARTERY. This artery issues from the orbit above the tendon of the orbicularis palpebrarum, passes to the root of the nose, and unites with the terminating branches of the external maxillary artery. 372 VASCULAR SYSTEM X. THE FRONTAL ARTERY. This artery passes out of the orbit, and ascends on the forehead, where it is entirely distributed. After the inter- nal carotid has given off the ophthalmic artery, it furnishes the following branches: I. THE COMMUNICATING ARTERY OF WILLIS. This artery commences from the internal carotid after the ophthalmic, passes backwards and a little inwards on the side of the pituitary body and mammillary eminences, and communicates with the posterior cerebral artery, which is furnished by the basilar. II. THE ARTERY OF THE CHOROID PLEXUS. This artery commences above the preceding; it passes outwards and backwards near the crus cerebri, penetrates into the lateral ventricle, and is distributed to the choroid plexus. III. THE ANTERIOR CEREBRAL ARTERY. This artery passes under the anterior lobe of the brain, e, Fig. 193, where it approaches that of the opposite side, and anastomoses with the communicating artery of Willis. It sends off branches to the fonix, the anterior commisure, and the septum lucidum. Afterwards the cerebral artery is directed forwards, turns round the anterior part of the corpus callosum, and takes the name of that part, termi- nating on its posterior surface. IV. MIDDLE CEREBRAL ARTERY. This artery passes outwards and backwards, and dips OF THE ARTERIES. 373 into the fissure of the anterior and middle lobes of the brain, where it divides into two branches, one for the ante- rior, the other for the middle lobe of the brain. SUBCLAVIAN ARTERY. Fig. 190. This artery, a, is so named from its situation under the clavicle; it is situated at the superior part of the chest, and extending from the arch of the aorta ; it proceeds un- der the clavicle, b, g, and over the middle of the first rib, passing between the anterior and middle scaleni muscles, then runs under the arch of the pectoralis minor, I, and enters the axilla, where it assumes the name of the axillary artery. The right subclavian arises from the arteria inno- minata, the left separates from the aorta at the termination of its arch. These arteries give branches directly upwards, and directly downwards to the neck, throat, and chest. 374 VASCULAR SYSTEM BRANCHES OF THE SUBCLAVIAN ARTERY. I. VERTEBRAL ARTERY. This artery is the largest branch of the subclavian, and extends to the brain. It arises from the upper and back part of the subclavian, a, ascends behind the inferior thy- roid artery on the vertebral column, enters the foramen at the base of the transverse processes of the sixth cervical vertebra, and takes its course through the canal formed by the union of the foramina of the transverse processes, c, c, c, c, c, of the other vertebrae of the neck. At the dentata, or second vertebra, it leaves this canal, curving upwards, backwards, and outwards, and perforates the transverse process of the atlas or first vertebra; it then passes between OF THE ARTERIES. 375 this vertebra and the occiput, forming a second curve; lastly, it enters the skull at the great occipital foramen by the side of the spinal marrow, and, penetrating the dura mater, mounts upwards and forwards between the corpora olivaria and pyramidalia, as seen in Fig. 193, b, b, uniting with the corresponding vertebral artery to form c, the ba- silar artery. The vertebral artery sends off the following branches: I. The posterior spinal artery, which arises near the corpora pyramidalia, proceeds downwards and inwards behind the spinal marrow, and is distributed on its poste- rior surface as far as the second lumbar vertebra. 2. The anterior spinal artery, which commences near the termination of the vertebral artery, and descends on the anterior surface of the spinal marrow. On a level with the occipital foramen it unites with the artery of the oppo- site side to form a common trunk, which descends as far as the lower extremity of the spinal cord, distributing branches on either side of it, and finally communicating with the middle sacral artery. 3. The inferior cerebellic artery, which commences at the termination of the vertebral, or sometimes at the basi- lar, and proceeds in a serpentine course, distributing nume- rous branches to the eighth and ninth pair of nerves, to the pia mater, and to the fourth ventricle, and to g, the whole inferior surface of the cerebellum. 376 VASCULAR SYSTEM II. BASILAR ARTERY. Fig. 193. The basilar artery, c, is formed by the union of the two vertebral arteries, b, b; it extends along the central groove of the pons varolii, and divides into the following branches : The superior cerebellic artery, which proceeds outwards and backwards, and descends on the upper surface of the cerebellum, where it spreads out into numerous ramifica- tions. The posterior cerebral artery, which proceeds down- wards to the posterior part of the lobes of the brain, di- vides into very many branches to supply the different parts of this region, and receives the communicating branch of Willis, which is given off by the internal carotid artery. OF THE ARTERIES. 377 III. INFERIOR THYROID ARTERY. This vessel, Fig. 187, d, commences at the superior part of the subclavian artery, o: it extends vertically on the anterior scalenus as far as the fifth vertebra, where it turns inwards towards the thyroid gland, and sends off internal and external branches to the trachea, esophagus, longus colli, and other muscles in this region ; a branch called the ascending cervical extends upwards as far as the rectus anticus major, and is distributed to the scalenus anticus, the longus colli, and the splenius muscles; the inferior thyroid artery, at the lower part of the gland, divides into numerous branches, which supply this organ, and anastomose with those of the opposite side, and with those of the superior thyroid artery. INFERIOR BRANCHES OF THE SUBCLAVIAN ARTERY. I. INTERNAL MAMMARY ARTERY. This artery, Fig. 197, e, arises from the subclavian, op- posite the inferior thyroid, passes inwards and downwards in front of the scalenus anticus muscle, enters the thorax, descends along the sterno-costal cartilages, between these and the pleura costalis, and divides into two branches near the ensiform cartilage. It furnishes several branches to adjacent muscles, and afterwards sends off the following branches: The anterior mediastinal artery, which descends in the superior separation of the anterior mediastinum and divides into branches, which supply the thyroid and thymus glands, the pleura, and the cellular tissue of the mediastinum. The superior diaphragmatic artery, which accompanies vol. i. 49 378 VASCULAR SYSTEM the nerve of the same name, supplies the fibrous membrane of the pericardium, the thymus gland, and the medias- tinum, and at length is lost in the fleshy fibres of the dia- phragm. It also furnishes external and internal branches: the external supplying the intercostal muscles, the internal passing through them, and supplying the muscles of the thorax and abdomen. II. SUPERIOR INTERCOSTAL ARTERY. This artery, Fig. 196, g, commences at the lower and Dack part of the subclavian, and descends under the pleura in front of the neck of the first and second ribs, where it generally terminates. In front of these ribs it sends off a posterior and an external branch : the former is distributed to the muscles of the back, the latter to the intercostal muscles, the periosteum of the vertebrae, the esophagus, and the bronchi. In the second intercostal space it fur- nishes external and internal branches, which follow pre- cisely the same course as the preceding, and are distributed to the muscles or communicate with the first intercostal artery arising from the aorta. EXTERNAL BRANCHES OF THE SUBCLAVIAN ARTERY. I. TRANSVERSE CERVICAL OR POSTERIOR SCAPULAR ARTERY. This artery, o, is directed transversely outwards, wind- ing along the scaleni muscles above the nerves which form the brachial plexus ; then curving obliquely under the trapezius, the levator anguli scapulae, and the rhomboideus, it terminates at the posterior border of the scapula, and may be traced to its inferior angle. Near its origin this artery gives off several branches, which ascend, and lose themselves in the muscles at the side of the neck. OF THE ARTERIES. 379 II. SUPERIOR SCAPULAR ARTERY. This artery commences often at the preceding or at the superior thyroid, takes a tortuous course behind and be- neath the clavicle, and arrives at the superior border of the scapula; it afterwards passes above the coracoid ligament, sending branches to the trapezius, and ultimately descends into the infra-spinatus fossa, between the bone and the infra-spinatus muscle. III. POSTERIOR OR DEEP CERVICAL ARTERY. This artery commences at the posterior part of the sub- clavian, behind the anterior scalenus ; it passes between the transverse processes of the two last vertebrae of the neck, and extends to the great complexus muscle. AXILLARY ARTERY. This artery is the direct continuation of the subclavian; it is situated at the superior and lateral part of the thorax; and in the axilla it extends from the first rib, in the inter- val of the two scaleni muscles, as far as the inferior margin of the tendon of the latissimus dorsi. The axillary artery is seen in Fig. 190, proceeding under the clavicle, b, g, and under the arch formed by the pectoralis minor, h, I. In the axilla it is surrounded by branches of nerves of the brachial plexus, which form a sort of sheath for the artery. The corresponding vein is always placed before the artery, and it is further protected by a quantity of cellular tissue and lymphatic glands. When it has passed the anterior edge of the pectoralis major, it assumes the name of the brachial artery. 380 VASCULAR SYSTEM BRANCHES OF THE AXILLARY ARTERY. I. ACROMIAL ARTERY. This artery, h, commences at the anterior part of the axillary ; it descends obliquely towards the deltoid muscle, and in the narrow space which separates this muscle from the great pectoral; it then divides into a superior and inferior branch: the former ramifies on the shoulder joint, the latter is distributed to the deltoid and the great pec- toral muscles. II. SUPERIOR THORACIC ARTERY. This artery, I, generally arises with the former artery, and descends between the two pectoral muscles, to which it is distributed. III. LONG THORACIC OR EXTERNAL MAMMARY ARTERY. This artery, i, commences a little lower down than the preceding; it descends from behind forwards, on the upper and lateral part of the chest, along the inferior margin of the pectoralis major, supplying this muscle, the serratus magnus, the intercostals, the lymphatic ganglia of the axilla, the integuments, and the mamma. IV. INFERIOR SCAPULAR0. This artery, k, arises from the inferior part of the axil- lary, opposite the inferior border of the tendon of the subscapularis muscle; it descends along the lower border of this muscle, and gives off an inferior and superior c Frequently termed the subscapular artery. OF THE ARTERIES. 381 branch ; the former supplies the serratus magnus, the latissimus dorsi, the teres major, and the integuments ; the latter is distributed to the various muscles of the scapula, and to the articulation of the shoulder. V. POSTERIOR AND ANTERIOR CIRCUMFLEX ARTERIES. The former of these arteries, m, arises from the poste- rior part of the axillary, passes backwards, turns round the upper part of the humerus, and is lost in the deltoid mus- cle ; the latter, n, is generally furnished by the preceding, and proceeds under the coraco-brachialis and short head of the biceps ; it turns also round the humerus, and is dis- tributed to the deltoid muscle. 382 VASCULAR SYSTEM BRACHIAL ARTERY. Fig. 194. OF THE ARTERIES. 383 This artery, a, is a continuation of the axillary; it is situated at the inner and fore part of the arm, and passes along the inferior edge of the coraco-brachialis. About the middle of the os brachii it crosses over the tendinous attachment of that muscle, being situated between the fleshy mass of the biceps and the upper fibres of the bra- chialis externus. This artery then proceeds behind the inner edge of the biceps, descending between that muscle and the fibres of the brachialis internus; in approaching the lower extremity of the os brachii, it is inclined for- wards towards the bend of the arm, and lies at i, beneath the aponeurosis, which is continued from the tendon of the biceps flexor cubiti. The brachial artery sends off nume- rous branches to the different muscles of the arm, two of which are more considerable than the others, and are termed muscular branches. I. SUPERIOR MUSCULAR BRANCH, OR DEEP HUMERAL. This artery, b, commences at the inner side of the brachial artery, immediately after it has left the axilla, passes between the triceps and the humerus, accompanied by the muscular spiral nerve, and proceeds between the brachialis externus and the short portion of the triceps, then divides into branches, which supply the triceps near the olecranon and the super-adjacent integuments. II. THE INFERIOR MUSCULAR ARTERY. This artery, c, is sent off from the brachial about two inches lower than the preceding; it descends among the muscles of the inside of the arm, and is lost about the inner condyle, k. 384 VASCULAR SYSTEM III. THE RAMUS ANASTOMOTICUS MAGNUS. This artery, e, commences about two or three inches above the inner condyle of the os brachii; it is distributed about the elbow, and its principal branches communicate with the recurrent branches of the arteries of the fore-arm. IV. THE EXTERNAL BRANCHES OF THE BRACHIAL ARTERY. These arteries, /, are small, and supply the coraco-bra- chialis, the brachialis internus, the biceps, and the inte- guments. The anterior and posterior branches of the brachial artery are short and slender, their number is very indeter- minate, and they penetrate the muscles of the front or back part of the arm. OF THE ARTERIES. 385 BRANCHES BY WHICH THE RADIAL ARTERY TERMINATES. Fig. 195. The brachial artery, a, divides at k into three branches: vol. i. 50 386 VASCULAR SYSTEM 1st, the radial, n, o ; 2nd, the ulnar, 1; and 3rd, the in- terosseous artery, m; the last two, however, generally arise by one trunk, as at /, in this figure*1. THE RADIAL ARTERY. This artery is situated at the anterior and front of the fore-arm : it follows the direction of the brachial artery, a, and at the bend of the arm, k, separates at an acute angle from the ulnar. The radial artery extends from the upper extremity of the radius, k, as far as the articulation of the carpus, o, here it turns outward, passes between the two first metacarpal bones into the palm of the hand, where it forms the deep palmar arch, p. But it is important more particularly to understand its relative connections. Above, it lies between the pronator teres and the supinator longus, and about the middle of the fore-arm passes over the lower attachment of the pronator teres, continuing its course between the supinator longus and the flexor carpi radialis, accompanied by a branch of the musculo-spiral nerve. At the lower extremity of the radius it divides into two branches, which are distributed to the hand. The branches of the radial artery, in its course along the fore-arm, are as follows: 1. The radial recurrent, which passes outwards and upwards near the elbow, and is distributed to the outer condyle, where it anastomoses with branches of the bra- chial : see Fig. 194. 2. The internal branches, which are very numerous, are distributed to the muscles of the anterior and superficial layer of the fore-arm. d The division of the brachial artery is not always at the same point. I have not unfre- quently observed it about the middle of the arm, and sometimes as high as the axilla. OF THE ARTERIES. 387 3. The superficiales vola, Fig. 194, h, which descends upon the anterior annular ligament of the wrist, distributing a number of twigs to the muscles and integuments of the palmar region. 4. The radial artery at the back of the wrist is only covered by the tendons of the abductor pollicis longus, the extensores pollicis, and the integuments, and ramifying on the back of the hand, is named the dorsal artery of the wrist. 5. The dorsal artery of the metacarpus passes imme- diately over the second metacarpal bone, descends on the back of the hand, and is sometimes prolonged to the fore- finger. 6. Small vessels supply the back part of the thumb, termed the dorsal arteries of the thumb. On entering into the palm of the hand, the radial artery divides into two branches : 7. The artery of the thumb, which supplies a branch to the outer edge of the fore-finger. 8. The deep palmar arch, p, which is obvious in the preceding figure, passes transversely from the thumb over the metacarpal bones, and terminates by anastomosing with a branch of the ulnar artery. The deep palmar arch fur- nishes twigs to the interosseous muscles, and to the deep- seated parts of the palm of the hand. THE ULNAR ARTERY. This artery, I, is larger than the radial; it is situated at the anterior and inner part of the fore-arm, and extends from the bend of the arm as far as the palm of the hand. It takes its course under the pronator teres, the flexor carpi radialis, the palmaris longus, and the flexor sublimis perforatus, but passes over the flexor profundus perforatus. 388 VASCULAR SYSTEM It descends between the two last-mentioned muscles, and is found on the ulnar edge of the arm, at the outer edge of the flexor carpi ulnaris; it then proceeds over the annular ligament of the wrist, and under the palmar aponeurosis, until it arrives at the metacarpal bone of the little finger, where it forms the superficial palmar arch, seen in Fig. 194, g. The branches given off by the ulnar artery in its course along the fore-arm and wrist, are the following: 1. The anterior and posterior recurrent arteries arise from the ulnar artery, immediately below the elbow. The anterior is distributed to the fore part of the inner con- dyle, the posterior to the back part of the same process of bone. These arteries communicate with branches of the brachial. 2. The ulnar artery furnishes numerous branches to the muscles of the fore-arm. 3. The anterior and posterior interosseous arteries: the former, Fig. 194, at I, descends in front of the inter- osseous ligament, between the flexor longus pollicis and flexor profundus perforans, and arriving at the edge of the pronator quadratus, m, passes between the radius and ulna to the back part of the arm, and spreads its extreme branches on the wrist and back of the hand. The latter, or posterior interosseous artery, after traversing the inter- osseous ligament beneath the anconeus, sends off the inter- osseous recurrent, which ramifies on the back part of the elbow joint, and extends between the supinator brevis and abductor longus pollicis manus, and afterwards between the two layers of the posterior muscles of the fore-arm as far as the wrist. 4. The superficial palmar arch, Fig. 194, g, is a con- tinuation of the ulnar artery, and is situated above the ten- dons of the flexor sublimis perforatus, immediately beneath the palmar aponeurosis ; it commences at the inner side OF THE ARTERIES. 389 of the hand, crosses the metacarpus, and terminates at the root of the thumb by branches which unite with the radial artery. The convexity of the arch is turned towards the fingers, and furnishes the collateral branches of the fingers, namely— 1. A branch to the muscles and inner edge of the little finger. 2. The first digital artery, which furnishes two bran- ches, one to the outer side of the little finger, the other to the inner side of the ring finger. 3. The second digital artery, which in a similar manner furnishes branches to the outer edge of the ring finger, and to the inner side of the middle finger. 4. The third digital artery, which is distributed to the outer edge of the middle finger, and to the inner edge of the fore finger. 5. The ramus pollicis ulnaris, or last branch of the ulnar artery, which supplies the muscles of the thumb. 390 VASCULAR SYSTEM ARTERIES FURNISHED BY THE THORACIC AORTA. Fig. 196. BRONCHIAL ARTERIES. There are generally two bronchial arteries, a, b, one on the right side, the other on the left; they are distributed to the bronchi, and ramify in the pulmonary tissue. OF THE ARTERIES. 391 (ESOPHAGEAL ARTERIES. The number of these arteries varies from two to five or six, and curving to the right and left ramify on the eso- phagus. POSTERIOR MEDIASTINAL ARTERIES. These arteries are very numerous, and ramify in the posterior mediastinum and on the aorta. INFERIOR INTERCOSTAL ARTERIES. There are nine or ten inferior intercostal arteries on each side ; these commence at the posterior lateral part of the aorta; they pass over the bodies of the dorsal vertebrae to the posterior extremity of the ribs, and entering the intercostal spaces each artery divides into two branches, a dorsal and an intercostal; the former penetrates the ver- tebral canal by the intervertebral foramen, and ramifying on the spinal marrow, passes out between the transverse processes to the dorsal and lumbar muscles ; the latter, which is the largest branch, proceeds in the intercostal space beneath the pleura, and divides into an inferior and a superior branch. The inferior intercostal artery pro- ceeds along the superior edge of the rib which is beneath it; the superior intercostal passes along a groove in the inferior edge of the rib above it; but towards the sternal end of the rib it is situated in the middle of the intercostal space. The intercostal arteries terminate in front of the thorax by communicating with the internal mammary. 392 VASCULAR SYSTEM ARTERIES FURNISHED BY THE ABDOMINAL AORTA. THE RIGHT INFERIOR DIAPHRAGMATIC ARTERY. This artery generally arises from the aorta by itself, sometimes with the left, ami occasionally from the coeliac artery. It ascends on the outer side of the right pillar of the diaphragm, and divides into two branches, which pass between the liver and diaphragm, supplying the right part of the diaphragm, and giving two or three branches to the surrenal capsule. LEFT INFERIOR DIAPHRAGMATIC ARTERY. This artery, which arises with the preceding, furnishes branches to the left pillar of the diaphragm, the esophagus, the surrenal capsule, and finally ramifies on the phrenic centre of the diaphragm, Fig. 201, a. CffiLIAC ARTERY. This artery is large and short, and is situated between the small lobe of the liver (the lobulus spilegii) and the small curvature of the stomach ; it proceeds at a right angle from the abdominal aorta, between the pillars of the diaphragm; opposite the last dorsal vertebrae it passes hori- zontally forwards and divides into three branches, namely, the coronary artery of the stomach, the hepatic and the splenic arteries. The cceliac artery isjseen in Fig. 201, e. OF THE ARTERIES. 393 I. CORONARY ARTERY OF THE STOMACH. Firr- 197. This artery, h, follows the small curvature of the sto- mach as far as the pylorus, where it communicates with the pyloric artery. It furnishes— The (Esophagal branches, which arise near the cardia, and ascend upon the oesophagus. VOL. I. 51 394 VASCULAR SYSTEM The gastric branches, c, which originate at the small curvature of the stomach, and pass over the surface of a, this organ. Frequently the coronary artery sends a very consider- able branch to the liver. II. HEPATIC ARTERY. This artery, I, is much larger than the preceding, and directs itself transversely to the right and under the lobu- lus Spilegii as far as the neck of the gall-bladder; it fur- nishes the following branches: The pyloric artery, which is found on the right side of the pylorus, c; passing from right to left along the small curvature of the stomach, communicating with the sto- machic coronary branch, and ramifying on the surface of the stomach and pylorus. The right gastro-epiploic artery, e, c, which arises on the right beneath the pylorus, and descending vertically behind the stomach, it passes from right to left along its greater curvature in the anterior lamina of the great omen- tum, i, i, i, and unites with the left gastro-epiploic artery: in Fig. 198, it is seen giving branches to the stomach, i, the duodenum, c, and pancreas, d. After furnishing these branches, the hepatic artery pro- ceeds towards the right side in front of the vena porta, be- hind the hepatic duct, to the right side of the lobule of the liver, where it divides into two branches. The right branch furnishes the cystic artery, which supplies the parietes of the gall-bladder, d, dips into the fissure of the liver, and ramifies in the right lobe. The left branch penetrates by the same fissure of the liver, and is distributed to the left lobe and the lobulus Spilegii, accompanying the divisions of the vena porta. OF THE ARTERIES. 395 III. SPLENIC ARTERY. Fig. 198. In this figure the stomach and liver is turned up to shew the pancreas and spleen. The splenic artery, e, at its commencement proceeds from the right to the left, forming several inflexions along the upper part of the pancreas, d, as far as the fissure of the spleen, f In this course it furnishes— The pancreatic branches, which supply the pancreas, d. The left gastro-epiploic branch, which ascends a little to the left towards the great extremity of the stomach, and then descends along the great curvature, at the middle of which, at g, it communicates with the corresponding artery of the right side. At a little distance from the spleen,/", the splenic artery divides into five or six branches, which penetrate this organ after furnishing— The vasa brevia, which are short branches passing from the divisions of the splenic artery, and are distributed to the large extremity of the stomach. 396 VASCULAR SYSTEM SUPERIOR MESENTERIC ARTERY. Fig. 199. This artery, a, commences at the anterior right part of the aorta a little below the cceliac, and passing downwards behind the pancreas and before a portion of the duode- num, it gains the upper part of the mesentery, between the two folds of which it enters, and passing from left to right forms a curve, the convexity of which is turned to the left and forwards. It terminates at the end of g, the OF THE ARTERIES. 397 ilium, communicating with d, the inferior right colic artery. It furnishes the following branches : 1st. The superior right colic artery, b, which supplies the arch, and left side of the colon, /, where that intestine begins to run over the kidney. 2nd. The middle right colic artery : this branch, h, proceeds to the right, and a little upwards in the meso- colon divides, and on the right side communicates with the superior right colic artery, and on the lower side furnishes fifteen or twenty branches, which, after frequently com- municating in the form of arches, proceed to the right side of the colon. The inferior right colic, d, or ilio-colic artery, which passes downwards to supply the caput coli, and the last portion of the ilium. Its branches communicate with the descending branch of the middle right colic artery, and with the extremity of the superior mesenteric artery itself6. BRANCHES WHICH ARE FURNISHED ON THE LEFT SIDE OF THE SUPERIOR MESENTERIC ARTERY. The convexity of this artery sends off fifteen or twenty branches, c, c, which proceed obliquely downwards, divide into small twigs there, and unite with each other very frequently in the form of arches. From these primary arches smaller twigs commence, which divide in the same manner, and constitute secondary arches by communicating similar to the first. These secondary arches in like man- ner produce twigs in a third series of arches: from these again a fourth and fifth series of minuter arterial arches e Although this artery \s generally named as a branch immediately issuing from the supe- rior mesenteric, yet it more commonly proceeds from the superior right colic; it is therefore represented as such in this figure. 398 VASCULAR SYSTEM may be traced to the border of the intestine, where they appear as a network, which finally ramify and subdivide to infinity over the surface of the small intestines, g, g, and supply the muscular and mucous coats. The distribution of this artery on the valvulae conniventes is very apparent when these vessels are filled with fine injection. The distribution of the several branches of the superior mesenteric artery is seen also in Fig. 200, a, b, f h, i, k. OF THE ARTERIES. 399 THE INFERIOR MESENTERIC ARTERY. This artery commences at the anterior part of the aorta, c, it descends a little to the left, enters the iliac mesocolon, and is extended to the rectum as far as the anus. It fur- nishes the following branches: 1st, The superior left colic artery, e, which extends to 400 VASCULAR SYSTEM the left side of the colon, and communicates with the left branch of the right colic artery, f. 2nd, The middle left colic artery, o, which is generally a branch of the preceding; its distribution to the colon, p, p, is obvious in the figure. 3rd, The inferior left colic artery, which proceeds to- wards the sigmoid flexure of the colon, and divides into two branches, d, g. The left colic arteries are arranged precisely the same as those of the right side; namely, after forming arches and areolae, they supply the coats of the intestine. When the inferior mesenteric artery arrives at the pos- terior part of the rectum, it divides into the superior ha- morrhoidal arteries, which descend along the posterior surface of this intestine, and communicate with the middle and inferior haemorrhoidal arteries. ARTERIES WHICH ARE FURNISHED LATERALLY BY THE ABDOMINAL AORTA. SURRENAL ARTERIES. There is one of these arteries on each side; they arise a little above the renal, pass transversely across the verte- bral column, and are distributed to the surrenal capsules, marked c, in Fig. 201. OF THE ARTERIES. 401 RENAL OR EMULGENT ARTERIES. Fig. 201. These arteries are of a large size, and very short; there is one on each side ; they pass off from the aorta at f transversely across the vertebral column, and arriving at vol. i. 52 402 VASCULAR SYSTEM the kidney, d, divide into two, three, or four branches, which enter between the pelvis of the ureter and the renal vein. SPERMATIC ARTERIES. These arteries, g, are two in number, very slender, and of considerable length; they commence at the anterior or lateral parts of the aorta, and sometimes from the renal; they descend on the sides of the vertebral column, in front of the psoas muscles, and ureters, n, and accompany the spermatic veins. In the male,—they pass out by the in- guinal ring, and sending some branches to the spermatic cord, they terminate in the epididymis and the testis. In the female,—they pass to the ovary, to the Fallopian tubes, the round ligament, and the sides of the uterus. LUMBAR ARTERIES. There are commonly four or five of these arteries on each side, which commence at the back part of the aorta, and are distributed to the spinal canal, the peritoneum, the muscles of the loins, and to the sides of the abdomen and pelvis. OF THE ARTERIES. 403 THE ARTERIES WHICH TERMINATE THE AORTA BELOW. MIDDLE SACRAL ARTERY. Fig. 202. At the fourth lumbar vertebra the aorta divides, Fig. 201, at i, into the primitive iliacs; and the middle sacral artery, o, commences at the back part of this divi.sion, and descends along the anterior surface of the sacrum, and terminates near the summit of the os coccygis: in the annexed figure this vessel is marked a. PRIMITIVE ILIACS. These vessels, b, c, d, e, are formed by the bifurcation 404 VASCULAR SYSTEM of the aorta. Separating from each other at an acute an- gle, they descend along the edge of the psoas muscle as far as the sacro-iliac articulation, where they divide each into the external and internal iliac arteries. The course of these vessels is very obvious in the figure preceding. INTERNAL ILIAC OR HYPOGASTRIC ARTERY. This artery dives almost vertically into the pelvis, in front of the sacro-iliac articulation ; and after a short course divides into a great number of branches. BRANCHES OF THE INTERNAL ILIAC ARTERY. I. ILIO-LUMBAR ARTERY. This artery proceeds from the internal iliac, opposite the base of the sacrum; it varies much in size, and ascends outwards and backwards, under the psoas muscle, then divides into an ascending and a transverse branch, which are distributed to the lumbar muscles. II. THE LATERAL SACRAL ARTERY. Sometimes there are two of these arteries on either side ; these vessels descend in front of the anterior sacral fora- mina, as far as the os coccygis. It furnishes external and internal branches: the former enter the sacral canal, and ramifying on the membrane which lines it, they pass out, and are lost on the muscles at the posterior part of the sacrum; the latter, ramifying in the sacral nerves and ganglia, and in the pyramidalis muscle. OF THE ARTERIES. 405 III. GLUTEAL OR POSTERIOR ILIAC ARTERY. Fig. 203. This is the largest branch of the internal iliac; it des- cends outwards and backwards, and passes out of the pelvis through the sacro-sciatic notch, above the pyramidalis muscle ; it then proceeds to the posterior part of the pel- vis, covered by the gluteus maximus, and divides into two branches: the superficial branch, c, is distributed to the gluteus maximus and medius and the sacro-sciatic liga- ment ; the deep-seated branch, a, b, ascends between the 406 VASCULAR SYSTEM gluteus medius and minimus, and is distributed to the mus- cles of this region, and to the capsule of the hip-joint. IV. UMBILICAL ARTERY. This artery passes obliquely forwards and inwards, as far as the superior lateral part of the bladder, from whence it ascends behind the anterior parietes of the abdomen to the umbilicus. In the adult, this artery is almost, oblite- rated ; but in the foetus, it appears to be a continuation of the internal iliac, and passes out by the umbilicus to form a part of the umbilical cord. V. VESICAL ARTERIES. These arteries present many variations in number and origin; they arise from the umbilical, middle hasmorrhoidal, internal pudic, and obturator arteries. The internal iliac furnishes a considerable branch, which supplies the fundus of the bladder, commencement of the urethra, prostate gland, the vesiculae seminales, and vas deferens; the ulti- mate ramifications reach to the rectum. VI. OBTURATOR ARTERY. This artery generally commences at the internal iliac, or the gluteal, and sometimes from the epigastric; it pro- ceeds to the obturator muscle, and advances as far as the obturator foramen, the superior part of which it traverses ; it issues from the pelvis through the space left by the obturator membrane, and divides into two branches, which are distributed to the hip-joint, and to the muscles on the inside of the thigh. OF THE ARTERIES. 407 VII. MIDDLE HEMORRHOIDAL ARTERY. This artery descends obliquely on the anterior part of the rectum; it supplies the tunics of this intestine, and com- municates with the superior and inferior haemorrhoidals. VIII. UTERINE ARTERY. The size of this artery is always in relation to the deve- lopement of the uterus; arising from the internal iliac, or internal pudic, it passes upon the broad ligament, and is distributed to the lateral and inferior parts of the uterus. IX. VAGINAL ARTERY. This vessel is not constant in its origin, for it commences at the internal pudic, the middle haemorrhoidal, or the umbilical artery; it proceeds to the vagina and external parts of generation. X. ISCHIATIC ARTERY. This vessel appears to be a continuation of the internal iliac artery; after supplying the rectum and bladder, it descends in front of the pyramidalis muscle, it proceeds through the great sciatic notch, and at its exit from the pelvis divides into numerous branches, which supply the gluteus maximus, the levator ani, the sciatic nerve, and the muscles of the posterior crural region. XI. INTERNAL PUDIC ARTERY. This artery is smaller than the ischiatic, and is frequently furnished by it. It descends before the sciatic plexus and 408 VASCULAR SYSTEM the pyramidalis muscle, and issues from the pelvis by the lower parts of the sciatic notch, between the pyramidalis and posterior border of the levator ani; it afterwards pro- ceeds between the two sacro-sciatic ligaments, to the in- ternal surface of the ischium, as far as the common attach- ment of the ischio-cavernosus and transversus perinaei, and here divides into two branches, which take a different course in the male and in the female, and of which one is inferior, the other superior. 1st. The inferior branch, or perineal artery, proceeds between the integuments and transversus perinaei, as far as the lower part of the scrotum, and is distributed to the muscles of the perinaeurn; some branches pass towards the rectum, termed the inferior hamorrhoidal arteries. The inferior branch afterwards penetrates the septum scroti, and supplies the integuments of the genitals. 2nd. The superior branch ascends above the transversus perinaei, along the ascending branch of the ischium, and the ramus of the pubis to the symphysis of this latter bone, where it divides into two branches, the dorsal artery of the penis, and the artery of the corpus cavernosum. 3rd. The transverse artery of the perinaum is furnished by the superior branch of the internal pudic, near the ori- gin of the latter ; it passes above the transversus perinaei muscle, and supplies the bulb of the urethra. 4th. The artery of the corpus cavernosum passes into the cavernous body, and divides into a great number of branches to supply its tissue. 5th. The dorsal artery of the penis, Fig. 204, f sup- plies the fibrous membrane of the corpus cavernosum, and terminates in the glans penis. In the female, the inferior branch of the internal pudic artery terminates in the external labia ; the superior is dis- tributed to the clitoris and orifice of the vagina. OF THE ARTERIES. 409 EXTERNAL ILIAC ARTERY. This vessel, b, d, is formed by the bifurcation of the primitive iliac artery ; it extends to the crural arch, where it takes the name of femoral artery. The external iliac descends obliquely outwards, along the inner and fore part of the psoas muscle, having on its inner side the external iliac vein. It furnishes the following branches :— I. THE EPIGASTRIC ARTERY. This artery proceeds from the inner side of the external iliac, at e, about an inch before it passes into the thigh ; it extends inwards and a little forwards, behind the spermatic cord, the direction of which it crosses towards the external border of the rectus abdominis muscle. About two inches above the pubis it is situated on the posterior surface of this muscle, and terminates by several twigs at the umbi- licus. Its distribution may be seen in Fig. 201, I. II. CIRCUMFLEX ILIAC ARTERY. This vessel, Fig. 202, f commences at the outer part of the iliac artery, and ascends obliquely outwards along the'external border of the iliacus muscle, as far as the an- terior superior spinous process of the ilium ; it then passes backwards, and divides into two branches ; its external branch supplies the transversalis and the internal oblique muscles ; its internal branch follows the line of the crista ilii, and terminates in the same muscles. In the subsequent figure it is marked b. VOL. I. 53 410 VASCULAR SYSTEM FEMORAL ARTERY. Fig. 204. OF THE ARTERIES. 411 Immediately the external iliac artery has emerged from under the crural arch at c, it assumes the name of femoral: it commences at the middle of the space which separates the anterior superior spine of the ilium from the pubis; it descends on the anterior and internal part of the psoas muscle, and upon the external femoral vein ; towards the lower part of the thigh it enters the aponeurotic sheath of the triceps adductor magnus, m, on its exit from which it takes the name of popliteal artery. To the surgeon, an acquaintance with the femoral artery is of so much im- portance, that its relative situation claims further notice. Anteriorly, the femoral artery is connected with the crural aponeurosis, the integuments, and the inguinal lym- phatic glands; it is situated in a triangular space, bounded above by the crural arch, on the outer side by the sartorius, and on the inner side by the middle adductor and the vas- tus internus. Farther down it is covered by the sartorius muscle, which crosses its direction. Posteriorly, it is situ- ated upon the pectineus and the middle adductor muscles. On the outer side it is connected at first to the crural nerve ; then to the tendon of the psoas and the iliac mus- cles; and lastly, it is placed upon the inner portion of the triceps, which separates it from the shaft of the femur. On its inner side, it is in contact with the femoral vein and the pectineus muscle, and at the lower part of the thigh it is concealed by the sartorius muscle. INTERNAL BRANCHES OF THE FEMORAL ARTERY. I. EXTERNAL PUDIC ARTERY. These vessels are two in number: one superficial, c, which commences near the crural arch, proceeds trans- versely inwards, and divides into branches, which are lost in the integuments of the inferior part of the abdomen, the 412 VASCULAR SYSTEM penis, f and the labia in the female ; the other is a deep- seated branch, distributed under the crural aponeurosis. EXTERNAL BRANCHES OF THE FEMORAL ARTERY. II. SUPERFICIAL MUSCULAR ARTERY. This artery commences nearly on a level with the pro- funda; it passes transversely outwards between the sarto- rius and rectus, and divides into ascending and descending branches, which supply the muscles and integuments of the upper part of the thigh. See Fig. 203, o. ANTERIOR BRANCHES OF THE FEMORAL ARTERY. ABDOMINAL SUBCUTANEOUS OR EXTERNAL EPIGASTRIC ARTERY. This is a very small artery; it commences immediately above the crural arch, and ascends between the abdominal aponeurosis and the integuments, as far as the level of the umbilicus. The other anterior branches of the femoral artery are very small, and are distributed to the cellular tissue and integuments. POSTERIOR BRANCHES OF THE FEMORAL ARTERY. ARTERIA PROFUNDA FEMORIS, OR DEEP MUSCULAR ARTERY. This vessel, h, is nearly as large as the femoral artery itself; it commences about two inches below the crural arch; it descends backwards between the adductor mus- cles and internal portion of the triceps, as far as the middle of the thigh. It then diminishes in size, passes through the aponeurosis of the adductor longus to the back part of OF THE ARTERIES. 413 the limb, and terminates in two branches, which enter into the short portion of the biceps femoris and the semimem- branosus. The deep muscular artery, which we have just described, furnishes the following branches: 1. The external circumflex artery, n, which commences at the outer side, passes outwards behind the sartorius and rectus femoris, and divides into two branches; the one is distributed to the parts about the hip joint, the other de- scends in the fore part of the thigh between the triceps extensor and the rectus femoris, in which it ramifies. 2. The internal circumflex artery, which is larger than the preceding, passes backwards between the pectineus and the tendons of the psoas and the iliac muscles, then divides into two branches, one of which supplies the mus- cles at the neck of the femur, the other is distributed to the flexors of the leg. 3.. The superior perforating artery. 4. The middle perforating artery. 5. The inferior perforating artery1. These vessels comprehend all the great muscular bran- ches of the profunda ; except the two circumflex arteries, they vary in number, and are proportioned in size to the bulk of the limb. These arteries perforate the adductors, and proceed to the back part of the thigh. A particular knowledge of the distribution and branches of the perfo- rating arteries is really unattainable, for they ramify in every direction, supply all the large mass of muscles on the back part of the thigh, and communicate freely with the sciatic, the gluteal, and the obturator arteries. A branch of the middle perforating artery penetrates into the femur by the nutritious canal which we observe on the linea aspera of that bone. f These arteries are irregular in place, size, and number; they are frequently named numerically, as the 1st, 2nd, 3rd, and sometimes branches are termed the 4th and 5th perfo- rating arteries. 414 VASCULAR SYSTEM POPLITEAL ARTERY. Fig. 205. ~SSt)rmrnmnt 'MmiMmm, fell This vessel, a, is a direct continuation of the femoral artery, the latter merely changing its name after it has per- OF THE ARTERIES. 415 forated the adductor magnus ; it descends into the ham between the condyles of the femur, and extends from the commencement of the inferior third of the thigh to the superior fourth of the leg. On the back part it is connected with the sciatic nerve, the popliteal vein, and the semi- membranosus ; afterwards, and more inferiorly, with the gastrocnemius, the soleus, and the plantaris ; it is sepa- rated above from the femur by a quantity of adipose tissue; farther down it rests upon the back of the knee joint; and below upon the popliteus and the tibialis posticus muscles. The popliteal artery, after giving off a number of small branches to the neighbouring parts, divides into three prin- cipal branches to supply the leg. BRANCHES OF THE POPLITEAL ARTERY. There are three superior articular arteries arising from the popliteal in the ham. 1. The internal superior articular arteries, e,f: there are generally two or three of these vessels, which vary much ; they descend inwards, pass under the tendon of the long adductor, proceed on the internal part of the femur above the condyle, and are distributed into the triceps muscle and the articulation of the knee. 2. The external superior articular artery, b, passes out- wards, turns on the external part of the femur above the condyle, and divides into two branches, the superior of which is lost in the triceps; the inferior descends on the external condyle of the femur. 3. The middle superior articular artery proceeds from the anterior part of the popliteal to supply the cellular and adipose tissue posterior to the crucial ligaments of the arti- culation of the knee. These and the following branches are given off by the popliteal to the upper part of the leg. The arteries just 416 VASCULAR SYSTEM named are distributed to the posterior surface, and dive into the substance of the gastrocnemii muscles, terminating in the soleus, the popliteus, and plantaris. There are two inferior articular arteries, which arise from the popliteal at the superior part of the leg, namely, 1. The internal inferior articular artery, g, which de- scends immediately behind the internal tuberosity of the tibia, to the internal part of the ligamentum patellae, rami- fying on the articulation of the knee and the periosteum of the tibia. 2. The external inferior articular artery, c, which descends between the popliteus and gastrocnemius, then passes under the tendon of the biceps and external lateral ligament, and is distributed to the articulation of the knee, the ligamentum patellae, and parts in this region. The popliteal artery having given off these arteries, descends behind the popliteal muscle, and divides into the anterior tibial, the peroneal, and the posterior tibial arteries. OF THE ARTERIES. 417 ANTERIOR TIBIAL ARTERY. Fig. 206. The anterior tibial artery, b, at its commencement is vol. i. 54 418 VASCULAR SYSTEM directed horizontally forwards ; it passes from the ham be- tween the inferior edge of the popliteus and the superior fibres of the soleus, then proceeding through the upper extremity of the tibialis posticus and a perforation in the interosseous ligament to arrive at the fore part of the leg; the artery afterwards passes downwards upon the interos- seous ligament, between the tibialis anticus and the exten- sor proprius pollicis, c; below the middle of the leg it advances more forward, crosses under the tendon of the extensor proprius pollicis, and is situated between that tendon and the tendon of the extensor longus digitorum, e; at the ankle it is extended over the front of the tibia; then having passed under the anterior annular ligament of the instep at d, it assumes the name of the dorsal artery of the foot. The posterior tibial artery furnishes the follow- ing branches: 1. The recurrent artery of the knee, which passes up- wards and inwards, supplies the upper extremity of the tibialis anticus, and is lost in the articulation of the knee, a, and the integuments. 2. Numerous small branches to the muscles on the fore part of the leg. 3. The internal malleolar artery, which ramifies over the inner ankle. 4. The external malleolar artery, which ramifies over the outer.ankle. DORSAL ARTERY OF THE FOOT. This artery, d, is the direct continuation of the anterior tibial, and extends over the upper surface of the foot to the posterior extremity of the first metatarsal bone, where it descends into the sole of the foot, by passing through the adductor of the second toe. It distributes numerous but very slender external and internal branches, to supply OF THE ARTERIES. 419 the adjacent parts of the foot. Two of these branches have been named the tarsal and metatarsal arteries ; these cross the tarsal and metatarsal bones, and pass obliquely to the outer edge of the foot. The interosseal arteries come off from the tarsal or metatarsal, and supply the interosseous spaces and supe- rior surface of the toes. A considerable branch proceeds from the dorsal artery of the foot, along the space between the two first metatar- sal bones, and divides into, The dorsal artery of the great toe, and an artery which is extended on the inner edge of the toe next to the great toe. PERONEAL ARTERY. This artery, h, Fig. 207, is smaller than the anterior tibial, and situated at the posterior and deep part of the leg; it descends upon the inner side of the fibula, giving numerous branches to the peroneal muscles at i, and the flexor of the great toe. At the lower part it divides into the posterior fibular artery, which, properly speaking, is the termination of the peroneal, descending behind the in- ferior articulation of the fibula, at k, to the posterior part of the foot, and is distributed to the heel and the ankle. 420 VASCULAR SYSTEM POSTERIOR TIBIAL ARTERY. Fig. 207. This vessel, e, is the continued trunk of the popliteal, a; it descends under the superior attachment of the soleus, between that muscle and the more deeply seated flexors of the toes ; it does not lie, however, in im- mediate contact with the muscular fibres, but like the femoral artery is invested by a strong sheath of con- densed cellular membrane. In its course the posterior tibial artery fur- nishes a number of small branches, which are chiefly distributed to the tibialis posticus and the flexor mus- cles, the skin, and the periosteum of the tibia; one of these branches, termed the nutritious artery of the tibia, descends upon the posterior surface of this bone, and penetrates into the medullary canal. As this ar- tery descends it gradually advances more forwards, follows the course of the flexor tendons, passing behind the inner ankle, f and upon this bone its pulsation may be felt; then sink- ing under the abductor pollicis, it divides into two branches— 1st. The internal plantar artery, which supplies the muscles situated on the inner edge of the sole of the foot, Fig. 208, b. OF THE ARTERIES. 421 2nd. The external plantar artery, a, which crosses Fig. 208. obliquely the three middle metatarsal bones, and forms the plantar arch, c, the convexity of which furnishes nume- rous branches to supply the lumbricales muscles ; and taking a similar course to the branches of the palmar arch, each anterior branch supplies the corresponding sides of the toes, in the same manner as the collateral arteries are distributed to the fingers. END OF VOL. I ( I ■h &*+*l T Mm Vii MM m mmm S*'.J.l'^-: rwi • ■ ?*titr &:-■ [&?: 5V.-',- .■.-';■: •••'■-: fe:■■ ■.'. **%