GIFT OF Miss E.M. Boulton LOCKED CASE , fi / , THE POCKET ANATOMIST: A COMPLETE DESCRIPTION OF THE ANATOMY OF THE HUMAN BODY, THE USE OF STUDENTS, M. W. HILLES, FORMERLY LECTURER ON ANATOMY AND PHYSIOLOGY AT THE WESTMINSTER HOSPITAL SCHOOL OF MEDICINE, ETC. SECOND EDITION. PHILADELPHIA: LINDSAY AND BLAKISTON. 1867. BIC IHO PKEFACE. To the student preparing for his examination at the several Medical Colleges, works which contain a con- densed description of the structures and functions of the human body are essentially useful, as they not only con- vey concise information on these subjects, but they also direct his attention to the most important points connec- ted therewith. Such works are not intended to supersede the more elaborate treatises on the various branches of medical science : these must be studied also, as, without their aid, it is vain to suppose, that sufficient information can be obtained to enable the student to enter upon the pursuit of the profession which he has selected, with credit to himself, or with advantage to those who may intrust their health and lives to his care. There is no "short road to knowledge:" the foundation must be first carefully laid, by close study and diligent research; when this has been accomplished, the attention will be profitably directed to the arrangement, classifica- tion, and condensation of the knowledge thus obtained; knowledge is not a burden, nor is it unprofitable: it is only in the pursuits of after life that we feel the truth of this, and begin to experience the advantage of having laid up, in our earlier years, a store of information upon which we may draw fearlessly on occasions of difficulty. 970070 Anatomy may be said to be the basis on which all medical science rests; without correct and extensive anatomical knowledge the practice of surgery must be fraught with danger, and that of medicine empirical and of doubtful advantage. The medical bodies of the United Kingdom happily insist on all candidates for their de- grees or diplomas possessing a competent knowledge of anatomy; it is much to be regretted that a deficient supply of subjects should still exist, and present serious obstacles to the attainment of that practical information which is so desirable. This work is based on a treatise favourably known to the profession as Savage's Anatomist, and written by my friend and former colleague, Mr. Henry Savage. It now appears, from its enlarged and altered form, rather as a new work than a new edition of a former treatise. I trust that in this form it will continue to meet with approval and support. CONTENTS. CHAPTER I. THE HEAD 13 Cranium 13 Occipito frontalis 13 Muscles of External Ear 14 Face 14 Muscles of ditto 14 " nose 16 " lower jaw 16 Vessels and nerves of face 16 Parotid gland 17 CHAPTER II. THE NECK 19 Muscles of ditto 19 " between lower jaw and os hyoides 20 " oftongue ' 20 " between os hyoides and sternum 21 * Thyroid gland 22 Triangles of neck 23 Submaxillary gland 24 Sublingual ditto 24 Vessels and nerves of neck 25 Deep muscles 25 Larynx 26 Thyroid cartilage 27 Cricoid " 27 Arytsenoid " 27 VI CONTENTS. THE NECK Epiglottis Epiglottic gland Muscles of larynx Pharynx Muscles of ditto Arteries and nerves Velum Tonsil..., CHAPTER III. THE UPPER EXTREMITIES 35 Muscles of anterior and lateral parts of trunk... 35 Muscles on posterior part of trunk 37 Superior extremity 41 Muscles of shoulder 41 " of arm 43 Arteries of shoulder 44 Nerves of ditto 45 Axilla 45 Mammary gland 45 Fore arm 46 Muscles of ditto 47 Vessels and nerves of ditto 50 Hand 51 Muscles of ditto 52 Vessels and nerves of ditto 54 CHAPTER IV. THE TRUNK 55 Thorax 55 Pleura 56 Anterior Mediastinum 56 Thymus gland 57 Lungs 57 Bronchial tubes 58 Vessels and nerves of lungs 58 Trachea 59 Posterior Mediastinum 60 CONTENTS. Vll THE TRUNK. PA E (Esophagus 60 Vena azygos 60 Thoracic duct 61 Abdomen 62 Muscles of abdomen 62 Diaphragm 65 Viscera of abdomen 67 Peritoneum 67 Stomach 69 Small intestines 71 Large ditto 72 Liver 74 Gall bladder 76 Pancreas .'. 77 Spleen 77 Hernia 78 Inguinal ditto 78 Femoral ditto 92 Urinary organs 100 Kidneys 100 Ureters 101 Suprarenal capsules 101 Bladder 102 Urethra 103 Male organs of generation 104 Scrotum 104 Testes 104 Spermatic cord 106 Vesiculse seminales 106 Prostrate gland " 106 Penis , 107 Perineum 108 Muscles of 108 Female organs of generation Ill Uterus 112 Ovaries 113 CHAPTER V. THE INFERIOR OR LOWER EXTREMITIES 114 Muscles of. 114 Vlll CONTENTS. THE INFERIOR OR LOWER EXTREMITIES. PAGE Muscles of hip joint 114 '' front and sides of thigh 117 " posterior part of thigh 119 Vessels and nerves of thigh 120 Leg 121 Muscles of. 121 Foot 124 Muscles of. 124 Vessels and nerves of leg and foot 127 CHAPTER VI. FASCIJE 129 Cervical 130 Abdominal 330 Pelvic 132 Perineal 132 Lata 133 Crural 135 Plantar 136 Brachial 137 Palmar 138 CHAPTER VII. VASCULAR SYSTEM 139 Heart 139 " structure of. 142 " development of. 143 " investments of. 143 Arteries 145 pulmonary ^ 145 aorta 145 innominata 147 carotid 147 " right common 147 " left common 147 " External 148 anterior branches 148 CONTENTS. IX VASCULAR SYSTEM. PAGE Arteries posterior 149 inner 149 terminal 149 internal 150 branches 150 Cerebral branches from Basilar 151 Subclavian 152 right ;. 152 " left 152 branches 153 Axillary 154 branches 154 Brachial 155 branches 155 Radial 156 branches 156 Ulnar 157 branches 157 Aorta Thoracic 158 Abdominal 159 Coaliac axis 159 Hepatic 160 Splenic 160 Sup. Mesenteric 160 Inf. Mesenteric 161 Renal 161 Spermatic 162 Terminal branches ' 162 Iliacas Communes 162 " internal 163 branches 163 Gluteal 164 Ischiatic 164 Int. Pudic 165 " External 166 branches 166 Femoral 166 branches 167 Profunda.... 167 X CONTEXTS. VASCULAR SYSTEM PAGE AORTA Popliteal 168 branches 168 Tibial anterior 168 " posterior 169 branches 169 Collateral circulation 170 Venou.- Sysrom 172 Vein, Internal Jugular 172 " Labial 172 " Ext. Jugular 172 " Axillary 172 Vena Innom., right 173 left 173 Vena cava, superior 173 " Vein, int. saphena 173 '*' ext. saphena 173 " popliteal K3 " common iliac 173 Vena cava inferior 174 " porta 174 Lymphatic system 174 Thoracic duct 174 CHAPTER VIII.J THE NERVOUS SYSTEM 1^6 Spinal cord 176 Medula oblongata 179 Corpus olivaria " restiformia Filamenta arciformia Pons Varolii 181 Crura cerebri Cerebellum Cerebrum Tuber cinereum Fissure of Sylvius Corpus callosum " striatum 189 CONTENTS. XI THE NERVOUS SYSTEM. PAGE Third Ventricle 190 Membranes of brain 191 Dura mater 192 Sinuses 192 Arachnoid r/r 194 Pia mater 194 Structure of the brain 194 Vessels 199 Spinal nerves 200 Cervical plexus 203 Brachial 204 Intercostal nerves 206 Lumbar plexus 207 Sacral 209 Cerebral nerves 211 Sympathetic system 214 Cerebral ganglia 216 Semilunar ganglion 216 CHAPTER IX. BONES, LIGAMENTS, AND JOINTS 218 Bones of the head 218 frontal 218 parietal 219 occipital 220 temporal 221 sphenoid 223 ethmoid ; 224 of face 225 Inferior maxilla 2-8 Temporo-maxillary articulation 229 Spine ! 230 " ligaments 231 Ribs 232 Sternum 233 Ligaments of ribs 234 Bones of upper extremity..,. 234 Shoulder joint 237 Bones of fore-arm 237 Xll CONTENTS. BONES OF THE HEAD PAGE Elbow-joint 238 Carpus 239 Wrist-joint 240 Bones of inferior extremity 241 pelvis 241 " articulations of 244 feinur 245 Hip-joint 246 Knee-joint 248 Ankle-joint 252 CHAPTER X. ORGANS OF SENSE 254 Eye 254 Nose...: 259 Ear 260 Tongue 262 Skin..., 263 THE ANATOMIST. The he'Jid; .n'ecK, trb'hk/a^<},extH;rmtas form the principal divisions 'of the lluman-i>bdy/ :> > CHAPTER I. THE HEAD Consists of the Cranium and Face. SECTION I. The Cranium is covered by the scalp, composed of 1. The Skin. 2. The occipito-frontalis muscle. 3. The periosteum. The skin of the scalp is dense and firm, and is fur- nished with hair and sebaceous follicles and granu- lated fat. Occipito-frontalis is bicipital, with a central tendon or aponeurosis, Or. two ext. thirds of the super, trans- verse occipital ridge, and adjoining part of the mas- toid process; Ins. nasal bones, int. angular process, the rest of its fibres intermixing with the corrugator sur percilii, and orbicularis palp. Covers the whole skull, excepting the temporal fossae. Use, to raise the skin of the forehead, eyebrows, and eyelid. The scalp is supplied with blood from the frontal arteries in front the temporal and aural on the sides, and the occipital 1 posteriorly ; its nerves are derived from the fifth, por- tio dura, ascending cervical, and first cervical branches; it is loosely connected to the periosteum 2 1 14 THE FACE. and bone by areolar tissue, and thus moves freely on the skull. On the side of the head are The Muscles of the External Ear, 3. Superior auris, or attollens aurem, Or. from the cra- nialaponeurosis on the side of the cranium, immedi- ately above the ex't. ear; Ins t'K> upper and anterior part of the cartilage of ths eir. Anterior auris, or attrahens aurem, Or- posterior part of zygomati/j projjo&s, and. cranial r at>6neurosis; Ins. front part'uf h -li::. Posterior auris, or retrahens aurum, Or. from the the mastoid process above sterno-mastoid; Ins. back part of concha. The use of these muscles is indica- ted by their names. SECTION II. The Face is covered by a delicate vascular skin, closely con- nected with the subjacent Muscles, 33. Orbicularis palpebrarum, Or. the upper edge of the tendo oculi, and int. ang. process; Ins. the lower edge of the tendon, ascending process of the maxilla sup., and inner third of the lower edge of the orbit. The tendon crosses the junction of the lower two-thirds with the upper third of the lacrymal sac. Use, to close theeyelids, by depressingtheupper, tocompress the lacrymal sac, and force the tears into the nasal duct. Corru gator super cilii, Or. inner end of the super- ciliary ridge ; Ins orbic. palpebr. at its middle. The. following four m. arise in succession from the inner canth. Levator labii super, alseque nasi, Or. narrow from the inner angular process beneath the tendo palpe- MUSCLES OF FACE. 15 bra?: Ins. skin of the ala nasiand upper lip. and into the orbic. oris muscle. Lcvator labti proprius, Or. broad, inner half of the edge of the orbit : Ins. skin and hair bulbs of the upper lip; supposed to render the hair erect, as in the feline tribes. Zi/ffomaticui? m-ir,^r Q;., narrow i>o t u ihe inf. edge of the os mala; ' .umled wit^i those of the above mus-cle. , Zygomct*iciiss( road u-oai a groove on the OS mala, a trove its lo\\i.v euge; i:u\ iiavyuv into the labial commissure. Lcvator anyuli oris (Caninus,) Or. broad from the canine fossa://?*, narrow with the zyg. maj. into the labial commissure; the infra orbitar nerve and artery appear between this and the levat. prop. m. Depressor anyuli oris. Or. broad from the ext. ob- liqueline of infer, maxilla ;'//<<. narrow with the zyg. major and eaninus m. into the labial commissure. Its fibres are partly confounded with those of the pla- tysma. Depressor labii inf., Or. broad from the same line as, but internal to, the last m. ; Ins. broad into the skin of the lower lip.: united with its fellow above, but separated below by the Lcrator labii inf. vclmenti, conical, Or. from a fossa close^othesymphysis menti; Ins. by diverging fibres into the skin ami hair bulbs of the skin. Th of the preceding muscles is indicated by their names, the zygomatici draw the angle of the mouth upwards and backwards. Ituccinator Or. 1, super, alveola 1 , from that of the first .iuolar tooth to the last ; "2. corresponding alveola* of the lower jaw; ;>, ptergo maxillary ligament; Ins. the labial commissure, its lower fibres crossing the upper. These muscles are antagonized by the succeeding. /V, to press the cheek against the teeth, so aa 10 preVvMit the food passing between them. 16 MUSCLES OF THE LOWER JAW. to assist in mastication, articulation, blowing, and sucking. Orbicularis oris. This sphinctic muscle is composed of two portions, corresponding to the upper and lower lips. Their fibres decussate at the labial commissure to become continuous, the upper -portion with the lower fibres r o'i,tke bucciriatOtf, 3,ntl;mdy versa. Use, to close and corrugate th&inc':. t Mkw^-f.f &t irv.se, ' Pyramid'alds ndsi. ' A few fibres of th'e frontalis m., descending on each side of, and parallel to, the nasal suture to be lost in the compressor nasi. Compressor nasi, Or. narrow from the edge of the canine fossa; the two m. expand so asHo cover the nasal cartilage and some part of thealse, and unite by means of a thin fascia on the dorsum nasi. Depressor alse nasi, Or. narrow close to the median line from a fossa on the alveola of the incisor tooth ; Ins. by diverging fibres into the the orbic. oris, alee nasi, and septum. Naso labialis, (Albinus,) from the under part of the septum nasi runs downwards and backwards, and is lost in the orbic. oris. Muscles acting on the Lower Jaw. To shut it, 2. Masseter, Or. 1, by a strong fascia from the ant. two-thirds of the edge of the zygoma, and adjoining portion of the super, maxilla; 2, by a thinner fascia from the post, third of the zygoma; 3, from the inner surface of the zygoma. Ins. the first portion, angle of the jaw; the second, ext. surface of the ramus; and third, ext. surface of the coronoid process. Temporalis, Or. I, Temporal fossa; 2. Temporal aponeurosis. Ins. by a strong narrow tendon into the coronoid process of the inf. maxilla, and sometimes by VESSELS AND NERVES OF THE FACE. 17 an additional fasciculus and tendon into the inner edge of the ramus. The horizontal motion of the lower jaw is effected by 2 m. Pterygoideus ext., Or. 1, the whole outer surface of the ext. pterygoid plate and adjoining portion of the tuberosity of the palate bone: 2, from a ridge on the temporal bone, which separates the temporal from the zygomatic fossa. Ins. fossa on the anterior surface of the neck of the condyle of the lower jaw and edge of the interarticular cartilage; the int. max. art. enters the pterygoid fossa between its two origins. Pterygoideus ext., Or. 1, fossa between the ptery- goid plates; 2, the hamular process; 3, tuberosity of the palate bone ; it passes downwards, backwards, and outwards, to be ins. into the inner surface of the angle of the lower jaw. The interval between the muscles below is traversed by the int. maxil. art. and vein, ^and the dental and gustatory nerves. The dental nerve and artery, in their descent, separate the latter muscle from the ramus of the jaw. The lateral or grinding motion of the lower jaw is effect- ed' chiefly by the pterygoid muscles, and in this the muscles of either side act alternately, and not con- jointly, as is the case in most other muscles. These last four muscles, although usually included amongst those of the face, do not strictly belong to this part. In the dissection of the face, numerous vessels and nerves are found supplying the skin, muscles, &c. The principal arteries are derived from the labial branch of the ext. carotid, the frontal branch of the ophthal- mic, the infra orbital, and the inferior dental branches of the internal maxillary artery; the nerves are the frontal, infra orbital, and inferior maxillary, or dental of the 5th, branches of the portio dura and of the cervical plexus. The masticatory actions of the masseter, temporal, pterygoid, and buccinator are supplied by the non ganglionic portion of the 3d division of the 5th. *9 18 THE PAROTID GLAND. The Parotid Gland is met with in dissecting the deep muscles of the face. There are three salivary glands on each side : 1 pa- rotid ; 2 submaxillary; 3 sublingual. Of these, the parotid is the largest; it is lodged in a quadrilateral fossa behind the rainus of the lower jaw, which bounds it in front; behind, is the mastoid process; above the zygomatic arch; and below, the stylo- maxillary ligament. Its superficial surface is cov- ered by the skin, a few fibres of the platysma, and a continuation of the cervical fascia; its deep surface passes in between the pterygoid muscles, and is in close contact with the int. carotid artery, int. jugular vein, 3rd division of the fifth nerve, the 8th and 9th cerebral nerves, and the styloid process; in its sub- stance are found the portio dura, or pes anserinus, the ext. jugular vein, and the ext. carotid artery, and its terminating branches. This belongs to the Conglomerate class of glands ; it is granular in struc- ture, the granules being separated by prolongations of the cervical fascia; a portion prolonged on the masseter muscle is called the soda parotidis. Its duct, Steno's duct, arises from the granules by small radicles, which unite and form the trunk; this crosses the masseter muscle from the anterior edge of the gland, perforates the buccinator, and opens into the mouth opposite the second molar tooth of the upper jaw. A line drawn from the lobe of the ear to nearly between the ala nasi and angle of the mouth indicates its course. The structure of this duct is fibro-mucous; the fibrous or ext. coat is re- markably strong, the canal is small, particularly at its orifice in the mouth. The gland is supplied with blood from the ext. carotid branches, its nerves are derived from the cervical plexus, the portio dura, fifth, and sympathetic. 19 CHAPTER II. includes the space between the lower jaw above, the clavicles 'beneath, and the cervical vertebrae poste- riorly ; it comprises the neck, properly so called, the mouth, pharynx and larynx, with numerous vessels and nerves. The integuments of the neck are thin; beneath them may be noticed the projections of the principal muscles the larynx on the mesial line, and the ext. jugular vein laterally. SECTION I. Muscles of the Neck. Platysma myoides. Commences in the subcuta- neous tissue over the pectoralis major and deltoid; Ins. into the fascia covering the parotid and masseter m., the labial commissure, and ext. oblique line of the lower jaw; some fibres are mixed with those of the depr. angul. oris, quadratus menti, and fellow. Use, to depress the angle of the mouth and lower jaw, and to corrugate the skin of the neck. Sterno-cleido-mastoideus, Or. fleshy from the sternal third or more of the clavicle, and by a round tendon, from the adjoining surface of the first bone of the sternum ; Ins. mastoid process and sup. transverse ridge of the occipital bone as far as the trapezius. Traversed by the spinal accessory nerve; the ext. jugular vein descends some way upon it ; its ant. edge is a guide to the common carotid artery. Use, if both muscles act, the interior portion will depress the head anteriorly, the posterior fibres posteriorly; the sternal portion of each muscle will also rotate 20 MUSCLES OF TONGUE. the head to the opposite side, the clavicular portion will depress it laterally. Between the Lower Jaw and Os Hyoides. Depressors of the Jaw. 3 Digastricus, Or. post, belly, groove behind the mas- toid process; ant. belly, a small fossa close to the symphysis menti. The two bellies are united by a round tendon, which is attached to the upper edge of the body of the os hyoides by means of a few ten- dinous fibres. The post belly passes through the stylo hyoid m. Mylo hyoideus, Or. whole length of the mylo hyoid ridge ; Ins. the whole length of the body of the os hyoides behind the digastric tendon, and to a me- dian tendinous line extending from that bone to the symphysis menti. It forms the floor of the mouth. Genio hyoideus. Or. the infer, of the two tubercles, on the inside of the jaw close to the symphysis ; Ins. narrow, body of the os hyoides close to the median line. These three muscles being removed, the following are brought into view: Of the Tongue, 5. Genio hyo-glossus, Or. narrow tendinous, from one of the sup. tubercles on the inside of the jaw, close to the symphysis, above the former m., it expands like a fan, to be Ins. 1, into the body of the os hyo- ides; 2, the pharynx between that bone r.nd the stylo-glossus; 3, with its fellow into the under sur- face of the tongue from the base to the apex; the hypoglossal nerve passes between its pharyngeal and lingual portions. Use to depress the tongue in the centre; the posterior fibres will draw the base of the tongue forward, the anterior will retract the tip. Lingualis, or Sublingualis, similar fibres are seen pn the dorsurn of the tongue, is a fasciculus of fibres MUSCLES OF NECK. 21 running from base to apex, between the above m. and the stylo and hyo glossi. Use, to draw the tip towards the base of the tongue, so as to render this convex superiorly. Hyo glossus, Or. 1, the body of the os hyoides, near the larger cornu ; 2, the whole length of this cornu. Ins. side of the tongue, between the lingu- alis and stylo glossus. The lingual artery crosses beneath it a little above the cornu, and the lingual nerve in front of it, a little above the artery. The gustatory crosses its upper margin. Use to depress the sides of the tongue, and render the dorsum con- vex. Stylo glossus, Or. narrow, inf. half of the styloid process; Ins. side of the tongue, from the palato- glossus to the tip ; a second portion divides the fibres of the hyo glossus, to join the transverse fibres of the tongue. Covered by the gustatory nerve, and sublingual gland. Use, to draw the tongue back- wards, and to elevate the lip. The two other styloid muscles elevate and dilate the pharynx. Stylo hyoideus, Or. narrow, back part of the styloid process, near its apex; Ins. body of the os hyoides, near the middle, gives passage to the post, belly of the digastricus. Use, to raise and draw back the os hyoides and tongue. Stylo pharyngeus, Or. vaginal process and back part of the base of the styloid process, passes be- tween the two sup. constrictors, with which its sup. fibres are lost; Ins. the edge of the ala of the thy- roid cartilage, and side of the pharynx. The glossa pharyngeal nerve runs on its outer side. Separates the ext. from the int. carot. and int. jugular vein. Between the Os Hyoides and Sternum, 4. Sterno hyoideus, Or. post, surface of sternum, and cartilage of the first rib, sternal end of clavicle, and capsule of the joint; Ins. lower border of the body 22 THYROID BODY. of the os hyoides. Use, to depress os hyoides, larynx, and pharynx. Thyro hyoideus, Or. oblique line on the ala of the thyroid cartilage; Ins. post, surface of the body of the os hyoides, and part of its larger cornu. Use, to approximate the os hyoides and thyroid cartilage. Sterno thyroides, Or. broad, post, surface of the sternum, below the sterno hyoideus, and from the first costal cartilage; Ins. oblique line of the ala of the thyroid cartilage. Use, to depress the larynx. Omo hyoideus, Or. superior edge of the scapula, behind the notch; 2, inf. edge of the os hyoideus at the junction of its body and cornu. The two por- tions are united, about an inch and a half above the clavicle, by a flat tendon, which is fixed to the latter bone by a portion of the deep cervical fascia. Use, to draw the os hyoideus downwards, and to one side. Two muscles extend from the sternum to the head. Immediately beneath the preceding muscles, and lying in front of the trachea, and extending later- ally on the sides of the larynx, is a soft, deep red- dish body, the thyroid gland or body. This is cre- scentic in shape, the concavity upwards, convex an- teriorly, concave posteriorly, and consists of two large lobes, the lateral lobes on either side, connected in front of, and in some rare cases behind the tra- chea, by a narrow isthmus, the central lobe. This body is larger in the infant and female subject. The structure of this body is cellular, the cells contain- ing a thin serous fluid; it is largely supplied with blood by the inferior thyroid from the subclavian, the superior thyroid from the ext. carotid, and fre- quently by a middle thyroid from the arch of the aorta. Its use is wholly unknown. As is usual in such cases conjecture has been very busy on the subject. The muscles of the neck, by their varied directions, divide the nearly square surface of this region into numerous spaces, generally of a triangular shape, TRIANGLES OF NECK. 23 which are of much importance, as containing several large bloodvessels, nerves, and other structures. The principle of these are 1. The Great Anterior Triangle. Bounded above by the lower jaw and stylo maxillary lig., which form its base ; in front, by the mesial line ; posteriorly, by the ant. edge of the sterno mastoid; its apex is, infe- riorly, at the sterno clavicular articulation. 2. The Great Posterior Triangle. Bounded below by the clavicle, which forms its base ; in front, by the post, edge of the sterno mastoid; behind, by the ant. edge of the trapezius ; its apex is superiorly, where these muscles approach, but do not meet. Each of these triangles is subdivided by the omohyoid muscle into two as follows 1. Anterior Inferior Triangle. Bounded by the mesial line as far as the os hyoideus, in front,Jwhicli forms its base; above by the anter. belly of the omo hyoid; below, by the ant. edge of the sternomastoid.; its apex is formed by the crossing of these muscles. This space contains the com. cartid art., internal jugular vein, and par vagum, with some smaller ner- vous filaments. 2. Anterior Superior Triangle. This is again sub- divided into two by the digastric muscle; vix. 1. Infra hyoid space. Bounded above by the os hyoides and digastric tendon, which forms its base; internally, by the ant. belly of the omo hyoid; ext. by the ant. margin of the sterno mastoid; its apex is at the decussation of these muscles. It contains the same parts, and generally the bifurcation of the com. carotid into its two branches, the ext. and int. carotids Supra hyoid, or digastric space. Bounded above by the lower jaw and stylo maxillary lig., which form its base; in front, by the ant. belly of the digastric; behind, by its post, belly ; its apex is at the tendon of this muscle, where it is attached to the os hyoides. This space contains the sub maxillary and sublingual 24 SUBMAXILLARY AND SUBLINGUAL GLANDS. glands, and labial and lingual arteries, the gustatory, ninth, and chorda tympani nerves, and Whartonian duct. 1. Posterior Inferior Triangle. Bounded below by the clavicle, which forms its base; above, by the post, belly of the omo hyoid ; in front, by the post, edge of the sterno mastoid ; its apex is at the decussation of these muscles. It contains the subclavian vein, the subclavian art. in its third stage, and brachial plexus ; and, more superficially, branches of the cervical plex- us ext, jugular vein, and some lymphatic glands. 2. Posterior Inferior Triangle. Much larger, is bounded behind by the ant. edge of the trapezius, which forms its base ; above and in front by the post, edge of the sterno mastoid; beneath, by the post, belly of the omo hyoid; its apex is at the decussation of these muscles. It contains the cervical plexus, and spinal accessory nerve, the transversaiis colli art., and numerous lymphatic glands. The subrnaxillary and sublingual glands met with in the digastric space form, with the parotid already described, the salivary glands. The submaxillary gland is lodged in a deep fossa beneath the lower jaw; bounded above by this, bone; beneath and in front by the ant. belly, of the digas,- tris; behind, by its post, belly. It is covered by the skin, platysma, and cervical fascia, and rests on the mylo hyoid andhyoglossus muscles. It is traversed by the labial art, which supplies it with blood. The structure of this gland resembles that of the parotid, but is less granular, as the cervical fascia does not send processes into its interior. Its duct, the Whar- tonian dtict, is thin and delicate, and opens on the side of the f raj num. linguae. A prolonged portion of this gland winds round the posterior edge of the mylo hyoid mus., and joins. The Sublingual gland, the smallest of the salivary glands, lies immediately beneath the mucous memb. DEEP MUSCLES OF NECK. 25 of the mouth, and above the mylo hyoid muse. It opens into the mouth by numerous orifices beneath the tongue; some join the Whartonian duct. All these parts are bound down, retained in their places, and more or less protected, by a dense layer of fibrous structure, the cervical fascia.' (See Fasciae.) SECTION II. The Vessels and Nerves of the Neck. The arteries met with in the neck are the right and left common carotid arteries, with their branches, the ext. and int. carotids, and the principal branches of them; the right and left subclavian arteries, and their principal branches; the veins are the internal and external jugular, and the subclavian, with their principal branches; the nerves are the cervical and brachial plexuses, with their principal branches; the par vagum or pneumogastric, the lingual or ninth, and sympathetic, with their numerous branches. SECTION III.. Deep-seated Muscles of the Neck, 5. The number of scaleni is variously stated. Albi- nus makes 5, Sabatier 3, Chaussier 1, recent wri- ters 2. Scalenus anticus; Or. upper surface of the first rib at its middle, Ins ant. transverse tubercles of the sixth, fifth, fourth, and third cervical vertebrae.-, se- parates the subclavian vein from the artery; the phrenic nerve descends diagonally across its ant. surface. Scalenus posticus ; Or. by two slips, 1, from the first rib between its subclavian depression and tubercle; 2. upper edge of the second, between its tubercle and angle \Ins. post, transverse tubercles of the six inf. cervical vertebrae-. -The subclavian artery and bra- 3 26 THE LARYNX. cliial plexus pass between the two scaleni. The use of the scaleni muscles is to elevate or fix the ribs to which they are attached, and to depress the neck forwards, and to one side. Longus colli, consists of three distincts orders of fasciculi, 1, Or. ant. transverse tubercles of thejfifth, fourth, and third cervical vertebras ; Ins. fore-part of the atlas; 2, Or. from the bodies of the first three dorsal vertebrae Ins. ant, transverse tubercles of the third and fourth cervical vert., 3. Or. the bodies of the four last cervical, and three sup. dorsal, and in- termediate ligaments; Ins. front of the axis and third cervical vertebrae-, -supports the great cervical vessel and nerves. Use, to bend the neck latterlly, and to rotate the atlas and head on the second vertebrae. Rectus capitis anticus major ; Or. ant. transverse tubercles of the third, fourth fifth, and sixth cervical vertebras; Ins. broad into the basilar process just in front of the foramen magnum. . supports the int. carot. artery, sup. cerv. gang. -.separates the 'ant. scaleni from the long. coli. Use, to bend the head and neck forward. Rectus capitis ant. minor, beneath the former m. Extends from the base of the transverse pr. of the at- las up wards and inwards to the basilar process. -.sup- ports the sup. cerv. ganglion. Use, to bend the head and neck forward and a little on one side. SECTION IV. The Larynx is the superior extremity of the trachea, with which it is continuous. It opens superiorly into the mouth, and lies on the mesial line of the neck, hav- ing the carotid' arteries, internal jugular vein, and par vagum on each side, the pharynx behind, and the sterno-hyoid, sterno-thyroid, and thyro-hyoid, muscles in front. THE LARYNX. 27 The larynx is composed of cartilages, fibre-carti- lage, muscles, mucous membrane, and glands. Four cartilages, thyroid, cricoid, and two arytsenoid; one fibro-cartilage, the epiglottis; fourteen muscles, the thyro-hyoid, crico-thyroid, thyro-arytaenoid, crico- arytsenoid lateralis, crico-arytsenoid posticus, aryte- no-epiglottic, inter, arytoenoid, and thyro-epiglottic. The last two are single muscles. One gland, the epiglottic. The mucous membrane lines the interior of the larynx. The thyroid cart, is the largest and superior. It consists of two quadrilat. plates, or alee, united in front forming the pomum Adami, and separated poste- riorly to receive the post ext. of the cricoid cart. The upper edge is irregularly convex, and is j oined by the thyro hyoid lig. to the os hyoides; its inf. edge is nearly straight, having a slight projection about its centre, and is connected to the first ring of the tra- chea by an elastic tissue, the crico-thyroid ligament. The posterior, or free margin rounded, is prolonged superiorly into the greater or superior cornu, at- tached to the os hyoides by a round and sometimes cartilaginous ligament. The inferior is shorter, and forms an articulation on the side of the cricoid cart. The outer surface, nearly plane, is marked by an ob- lique line, to which the sterno-thyroid and thyro- hyoid muscles are attached ; the inner surface is con- cave, and covers the crico-arytsenoid lateralis and thyro-arytsenoid muscles. The cricoid cartilage is ring-shaped, and lies be- neath the preceding. Narrow in front, deep behind, it fills here the interval between the alas of the thyroid cart.; its outer surface convex, gives origin to the cri- co thyroid muse, and more posteriorly articulates with the inf. cornu of the thyroid cart. ; behind this the posterior surface gives origin to the crico-ary tsenoidei postici muscles, between which is a prominent ridge ; the inner surface is lined by mucous memb.,the supe- 28 EPIGLOTTIC GLAND. rior edge of the cricoid cart, slopes upwards and backwards, and is marked by a convex articulating surface for the arytaenoid cartilage. The arytsenoid cartilages are triangular in shape, the base is concave, and rests on the edge of the cricoid cart. ; on it are two projections, one ext. for the in- sert, of the crico-arytamoid muscle, the other anterior for the attachment of the true chorda vocalis ; the apex is surmounted by the appendix or corniculum. H\\Q posterior surface concave, lodges the inter arytae- noid muse. ; the anterior convex gives attachment to the false chorda vocalis, and the aryteno epiglotti- dean fold. The internal surface is flat, opposed to its fellow, and covered by mucous membrane. These cartilages are very moveable, and thus influence the vocal chords. The epiglottis is situated immediately behind the root of the tongue, and over the upper opening of the larynx ; it is the shape of an oval leaf, concave poste- riorly, and covered by mucous membrane ; convex in front, it is attached to the root of the tongue by three folds of mucous membrane, theframum, the largest in the centre, the fraenula on. each side; to its edges are attached the aryteno epiglottidean folds; inferior- ly the epiglottis ends in a stalk-like process, which is inserted into the retreating angle of the thyroid cart, above the chorda vocalis. The use of the epiglottis is to cover the glottis in the act of deglutition; it is fibro-cartllaginous in structure. The epiglottic gland lies between the stalk-like pro- cess of the epiglottis and the thyro hyoid memb. Its glandular nature is very questionable. The larynx is connected superiorly to the os hyoides by the thyro hyoid ligament; this is best marked in the centre and at each posterior margin; the thyroid and cricoid cartilages are connected in front by the crico thyroid memb. or lig.; this is strong, and of a yellowish colour; a capsular ligament connects the articulation between the cricoid cart, and the inf. MUSCLES OF LARYNX. 29 cortiu of the thyroid, which is also lined by synovial membrane. In the interior of the larynx, and forming the rima glottidis, are the chordae vocales, two true and two false; the true are the stronger and inferior, the false superior and less distinct; both pass from the retreating angle of the thyroid cartilage to the tubercle on the base of the arytaenoid, the false one slightly curved, the true one straight; between them is a small fossa, the sacculus laryngis ; their struc- ture is fibrous. The use of the chorda vocalis is to open and close the rima glottidis, and to affect the tones of the voice by their different states of tension. Thyro-hyoideus, Or. oblique ridge of ala of thyr. cartilage ; Ins. lower border of cornu of os hyoides. Use, to raise and draw forwards the larynx and close the glottis. Crico-thyroideus, Or. from forepart of cricoid cart.; Ins. lower edge and cornu of thyroid cart. Use, to approximate the cartilages and make tense the vocal chords. Thyro-arytenoideus, Or. inner surface of thyroid cart. ; Ins. anterior and outer edge of arytenoid cart. Use, to draw the cartilages towards each other and narrow the rima glottidis. Crico-arytenoideus posticus, Or. from concave pos- terior surface of cricoid cart. ; Ins. base of aryte- noid cart. Use, to separate the chordae vocales and open the rima glottis. Crico-arytenoideus later alis, Or. side of cricoid cart, near its upper margin ; Ins. base of arytenoid cart. Use, to open the rima glottidis and relax the vocal chords. Arytenoidei. Fill the concave post, surfaces of the arytenoid cartilages, they consist of oblique and transverse fibres passing from one to the other. Use, to approximate the arytenoid cart., close the rima, and relax the vocal chords. 3* 30 THE PHARYNX. Some muscular fibres are occasionally met with in the thyro epiglottie and aryteno-cpiglottic folds, and are named after them. They are of little im- portance. The mucous membrane of the larynx forms a por- tion of the bronchial membrane, and resembles it in most particulars ; it is but lobsely connected to the subjacent parts by loose areolar tissue. The upper opening of the larynx or glottis commu- nicates with the isthmus faucium ; triangular, it is bounded in front by the epiglottis, which forms its base, its apex posteriorly at the convergence of the arytenoid cartilages, its sides are formed by the % aryteno-epiglottic folds. The lower opening or rima glottidis, a narrow aperture, slightly triangular, is bounded on each side by the true chordae vocales, the base is behind at the arytenoid cartilages, the apex in front, at the retreating angle of the thyroid cartilage, where the vocal chords arise. The rima glottidis is liable to much and constant change; the glottis varies butlittle. The arteries of the larynx are derived from the su- perior and inferior thyroid ; the nerves are branches of the par vagum or pneumogastric nerve; of these the superior laryngeal enters the thyro hyoid membrane, and is distributed to the arytenoid, thyro arytenoid, crico arytenoid lateralis, and crico thy- roid muscles, the inferior sends filaments to the same muse, to the crico arytenoid posticus and anas- tomoses with the superior. SECTION V. The Pharynx. The pharynx is a musculo-membranous tube, of a funnel shape, the larger extremity being continuous with the mouth and nares, the smaller with the oeso- phagus ; it extends from the base of the cranium to THE PHARYNX. . 31 lie 4th or 5th cervical vertebra; its length, subject i continual variation, is about four inches and a lialf ; its upper ext. is about two inches wide, and its lower one eleven lines. The following chain of iixed points affords attachment to its muscles. The cricoid and thyroid cartilages, os hyoides, stylo- hyoid ligament, base of the tongue, infer, maxilla, pterygo-maxillary lig. int. pterygoid plate and pet- rous bone; behind, they are attached to a strong aponeurosis, which descends from the basilar pro- cess and Eustachian tubes. Constrictor infer.; Or. 1, a triangular space on (he cricoid cartilage, between the crico thyroid and ary- tsenoid m.; 2, the oblique line, post, and sup. edge, and smaller cornu of the thyroid cartilage; Ins. with its fellow into the raph6 on the back part of the pharynx. .. The infer, laryngeal nerve passes be- neath its lower edge ; the super, under its upper edge. Constrictor mcdius. Triangular by its apex from the body and cornua of the os hyoides and stylo hy- oid lig. ; Ins. by its base with its fellow into the raphe. . its super, fibres are continued by means of a pointed tendon to the basilar process . . the stylo pharyngeus m. passes under its upper edge. Constrictor super, Or. 1, base of the tongue, where it is continuous with the genio hyo glossus, 2, post, extremity of the mylo hyoid ridge ; 3, pterygo max- illary ligament ; 4, lower third of the inner' ptery- goid plate, and by an aponeurosis from the petrous bone. I?is. tendinous raphe and basilar process . . an oval sinus (Morgagni) is left on each side, be- tween its upper fibres and the cranium. The phar- } T nx is also strengthened by fibres from the petrous, basilar, hamular, and styloid process. If the phar- ynx be opened by an incision along the raphe, there will be seen the velum, isthmus faucium, base of the tongue, epiglottis and seven openings viz., two of the nares, two Eustachian tubes, the mouth, the glottis, and the oesophageal entrance. 32 THE VELUM. The pharynx is lined literally by mucous mem- brane, continuous with that of the mouth, larynx, &c. This is covered by a prolongation of the cuticle termed the epithelium, which extends as far as the cardiac extremity of the oesophagus, where it termi- nates in a fringed margin. The arteries supplying the pharynx are derived from the pharyngea ascendens branch of the ext. carotid, the tonsillitic and nasal arteries ; it is sup- plied with nerves from the pharyngeal plexus formed by the pharyngeal branch of the par vagum, the glosso pharyngeal and sympathetic nerves. In deglutition the pharynx is first opened to re- ceive the morsel of food, its cavity is expanded from before backwards by the elevation of the larynx, and from side to side by the stylo pharyngei and palato pharyngei muscle ; the morsel of food having de- scended into it, the constrictor muscles contract from above downwards, and force the aliment into the oesophagus, and thence it passes into the stomach. The Velum is a kind of septum, projecting back- wards and downwards from the posterior edge of the palate into the pharynx, between the apertures of the mouth and nares; its muscles, ten in no., are inserted into a dense aponeurosis, usually called the expansion of the tensor palati m., continued from the fibrous portion of the palate, Eustachian tubes, and septum nasi. The velum is raised to a horizontal line by Levator palati, Or. yarrow, tendinous from the petrous bone near its summit, and the adjoining portion of the Eustachian tube; Ins. broad into the post, edge of the aponeurosis, and with its fellow into the whole length of the median line beneath the motores uvulae. Cir cum flexus palati, Or. 1, "scaphoid fossa atjthe base of the int. pterygoid plate; 2, adjoining portions of the sphenoid bone and Eustachian tube : it first descends, and is then reflected round the hamular THE TONSIL. 33 process, running horizontally inwards to be lost in the aponeurosis palati . -Separated from the latter m. by the sup. constrictor. Motores uvulse, two narrow fasciculi, descending along the median line, from the nasal spine to the end of the uvula-, -behind the levator palat. The velum is depressed by Palato glossus, Constrict, isthma. fauc., ant. pillar of the fauces narrow in the middle, its super, fibres are expanded with those of the following muscle into the inf. surface of the velum, and its inferior are lost with the stylo glossus in the side of the tongue. Palato pharyngeus. post, pillar of the fauces ; Or. broad, inf. surface of the palate, and whole length of the median line of the velum; Ins. whole length of the post, edge of the thyroid cartilage, and into the pharynx.-. The two pillars on each side are sepa- rated by the tonsil. The velum is lined on both surfaces by mucous membrane, and contains numerous glands, vesseLs, and nerves. Its arteries are derived from the pala- tine branches of the labial and int. maxillary: its nerves are branches from Meckel's ganglion, &c. From the centre of its free margin depends the uvula, composed of a few muscular fibres, some glands and cellular tissue ; on each side of this the ve- lum is curved or concave, and laterally terminates in two projections formed by the palato glossus and palato pharyngeus muscles; these form the half ar- ches of the palate, and separating inferiorly leave an interval in w r hich is lodged the amygdala or tonsil. The use of the velum is to prevent the food from passing upwards into the nares during deglutition; in this act it is raised and spread out so as to present an inclined plane forwards. It is also useful in forming the sounds of the voice. The amygdala, or tonsil, is lodged in the recess be- tween the half arches of the palate; it is almond sl;ap- 34 EUSTACHIAN TUBES. ed, the smaller extremity turned downwards; its structure is a number of mucous follicles, connected by cellular tissue, and covered by mucous membrane. The Posterior nares lie immediately above the velum, each is quadrilateral in shape, and conveys the air from the anterior nares into the isthmus faucium and lungs. The opening of the Eustachian tubes are situated one on each side of the posterior nares, opposite and a little above the post, extremity of the inf. spongy bone. They conduct the external air into the cavity of the tympanum. 35 CHAPTER III. THE UPPER EXTREMITIES Are attached to the trunk by means of the clavicle and numerous muscles ; some of them are situated on the ant. and some on the post, surface. SECTION I. Muscles of the Anterior and Lateral Parts of the Trunk* Thorax. Pectoralis major, Or. 1, sternal half of the clavicle; 2, ant. surface of the sternum; 3, the cartilages of all the true ribs, except the first and last. Ins. into the ant. lip of the bicipital groove by a double tendon; the ant. portion of which receives the upper and middle fibres, the posterior the infer, fibres. Use, to draw the arm inwards to the side, and rotate it inwardly; the clavicular portion raises the arm; if this be fixed the sternal and costal portions will assist in inspira- tion. Pectoralis minor, Or. third, fourth, and fifth ribs, just beyond their cartilages; Ins. into the point of the coracoid process.-, crosses the middle of the ax- illary vessels and nerves. Use, to depress the glenoid cavity inwards, also to assist in inspiration. Subclavius, fusiform, Or. by a flat tendon from the cartilage of the first rib. Ins. ext. half of the inf. sur- face of the clavicle-, -covered by a strong aponeurosis (costo-coracoid ligament) which arches over the ves- sels and muscle from its attachment to the clavicle to the coracoid process. Use, to depress the clavicle and shoulder inwards, to raise the first rib. Serratus magnus, Or. by nine or ten digitations from the ten sup. ribs. The first portion arises by 36 MUSCLES OF THORAX. one digitation from the first and second rib, is Ins. into the sup. angle of the scapula; a second portion by three digit, from the second, third, and fourth ribs, Ins. into the base of the scapula; third portion by six digit, from fifth, six, seventh, eighth, ninth, and tenth ribs, Ins. into the inf. angle of the scapula-. 'the five inf. digitations intersect with five of the obliquus de- scend, m. Ins. between the subscapularis and the rhomboidei and levat. scapulae. Use, to draw for- wards the scapula, to assist in inspiration the sup. fibres depress the glenoid cavity the inf. fibres ele- vate it by rotating the scapula. Inter costales, eleven internal and eleven external, on each side. They are attached to the opposite edges of each pair of ribs. The fibres of the ext. extend from the transverse processes of the vertebras to the costal end of the ribs, and by an aponeurosis from that point to the sternum: those of the internal ex- tend from the sternum to the angles of the ribs, and from that point by an aponeurosis to the spine.-, the intercostal vessels and nerves separate the two layers, -.the fibres of the ext. run downwards and out- wards in the direction of the obliq. extern, abdom-.- the internal in a contrary direction like the ob. int. abd. Use, to raise the ribs in inspiration. Levatorcs costarum, triangular, twelve on each side, Or. pointed from a transverse process above. Ins. broad ext. surface of the rib next below. Use, to raise the ribs. f Triangular stcrni, (serrat. min. antic.) Or. post, surface and edges of the lower part of the sternum, xiphoid, and adjoining costal cartilages. Ins. by dis- tinct digitations into the inf. margins of the sixth, fifth, fourth, and third costal cartilages. Use, to de- press the costal cartilages in expiration. MUSCLES OF BACK. 37 SECTION II. Muscles on the Posterior part of the Trunk. Dorsal muscles First layer, 2. Trapezius. Or. 1, thin and aponeurotic from the in- ner third of the sup. occip. ridge; 2, the twelve dorsal spinous processes; 3, from the last cervical spine, and the ligamentum nuchoe, which extends from that pro- cess to the occipital protuberance. Ins. the spine of the scapula, the acr omion process and the ext. third of the clavicle. '.from the same extent of the latter pro- cesses arises the deltoid. The tendinous fibres of the two muscles, from the sixth cervical to the third dorsal vertebrae, represent an ellipsis. Use, to elevate the shoulder, to depress the head backwards and to one side ; the sup. fibres raise the glenoid cavity directly, the inf. fibres rotate the scapula and so raise the glenoid cavity; to fix the scapula and thus antagonize the serratus magnus in inspiration. Latissimus dorsi, Or. from the six inferior dorsal spinous processes, by a strong fascia, which is con- founded with that of the int., obliq. and transversalis m.; from the spines of the lumbar vertebrae and sa- crum, and the post, third of the crista ilii: lastly, by so many digitations from the three or four last ribs; Ins. the inner and post, edge of the bicipital groove in front of the teres major, '.its costal attachments inter- digitate with the digitations of the ext. obliq.; some- times an additional slip arises from the inf. angle of the scapula. Use, to draw the arm backwards and in- wards, so as to rotate the palm of the hand inwardly; to compress the side of the thorax in respiration ; to assist in raising the ribs if the arm be previously fixed. Second Layer, 3. Rhomboidei, \, R. major, Or. four or five sup. dorsal spines; Ins. base of the scapula, from its spine to .its 4 38 MUSCLES OF BACK. inf. angle; 2, R. minor, Or. last cerv. spine; Ins. base of the scapula, between the two roots of the spi- nous process. Use, to draw backwards the scapula, and depress the glenoid cavity. Lcvator anyuli scapula, Or. post, transverse tuber- cles of the three or four sup. cerv. vert.; Ins. into the angle of the scapula, and its post, edge as far as the spine. Between the splenius colli and the scaleni and rect. capit. ant. Use, to raise the sup. angle of scapula, and depress the glenoid cavity. Third Layer, 4. Serratuspost. superior, Or. lig. iiuchse, first cervical, and second or third upper dorsal spines; Ins. by slips into the second, third and fourth ribs, beyond their angles. Use, to raise these ribs. Scrratus post, inferior, Or. two last dorsal and three upper lumbar spines; Ins. the four last ribs, just be- yond their angles. A fine but strong aponeurosis is stretched from one muscle to the other; which inter- nally is attached to the spinal processes, externally to the ribs, beyond their angles. Use, to depress the lower ribs in expiration. Splenius colli et capitis, both muscles arise from tfye two or three upper dorsal and the last cervical spines, and from the ligament, nuchge, as far as the third cer- vical spine; Ins. the s. colli into the post, trans, tuber- cles of the first and second, sometimes the third cervi- cal vertebras; the 5. capitis into the post, edge of the mast oid process, and adj oining third of the rough sur- face between the two occipital curved lines.-. S. colli, at its insertion, is behind the L. ang. scap. Use, to bend the head and neck backwards. Fourth Layer. The fourth layer is entirely covered by the above muscles and their fascia. MUSCLES OF BACK. 39 Longissimus dorsi. The mass of muscle bearing this name fills up the interval between the spinous pro- cesses and ribs, where it is bound down by the serratus fascia; in the lumbar region it is ensheathed by the superficial and middle lumbar fascia; in this situation the muscle constitutes the common origin of three dis- tinct muscles and their cervical prolongations. It is attached, fleshy, to the whole surface of the sacroiliac groove, and to the anterior surface of a dense fascia, which is attached to the post, third of the crista ilii and its posterior spinous processes, and to those of the sacrum, lumbar, and three last dorsal vertebrae. Sacro lumbalis (the external division,) Or. from the common mass; Ins. by distinct tendons into the six last ribs, near their angles; here it would cease, but the musculi accessorii, arising by distinct tendons from all the ribs successively from the last, join the muscle so as to enable it to deposit similar tendons on the angles of the six upper ribs, and to ascend in the neck under the name of Cervicalis ascendens. It is formed by the fourth or fifth upper musculi accessorii Ins. post, transverse tu- bercles of the fourth, fifth, and sixth cervical ver- tebrae. Longissimus dorsi (middle division,) Or. from the common mass; Ins. internally into the transverse pro- cesses of all the dorsal, and into the spinous processes of the five or six upper dorsal vertebrae ; and exter- nally into all the ribs between their tubercles and an- gles. It is prolonged into the neck as the Tranversalis cervicis. Its origin is formed by mus. access, from the third, fourth, fifth and sixth dorsal transverse process ; Ins. into the post, tubercles of the third or fourth upper cervical transverse processes, between the cerv. ascend, and trachelo mastoideus. Spinalis dorsi (inner division,) Or. from the inner- most portion of the common mass, which reaches as high as the ninth dorsal vert.; Ins. into the spinous 40 MUSCLES OF BACK. processes of the nine superior ribs; its cervical pro- longation is the Spinalis colli. It arises by mus. actessorii from the transverse processes of the five dorsal vertebrae, to be Ins. into the spinous processes of the six last cervi- cal.-, it is covered by the complexus. A deeper seated portion of the spinalis dorsi, from the dimi- nished length of its fasciculi, is called Semi spinalis dorsi. It arises from the dorsal trans- verse processes, from the fifth to the eleventh ; Ins. to the spinous processes of the three super, dorsal and two inf. cervical vertebrae. Deeper still, the fasciculi are much shorter, and are called Multifidus spinze ; Or. by slips from all the trans- verse pr., between the first sacral and the third dorsal vert.; each slip is Ins. into the first, second, or third spinous process next above ; the last is attached to the spine of the axis. Complexus, Or. 1, five or six upper dorsal trans- verse processes; 2, four last cervical articulating pro- cesses; 3, spinous processes of the last cervical, and two upper dorsal. Ins. inner half of the rough sur- face between the occipital ridges. Trachelo mastoideus (complexus minor,) Or. trans, processes of the four last cervical and four uppe'r dorsal vertebrae; Ins. back part of the mastoid pro- cess, beneath the splenius. Fifth Layer. Inter spinales. Double, in the cervical ; single, in tl^e lumbar and dorsal vertebrae. Indistinct in the latter. Inter transversalis. Double, in the cervical; single, in the lumbar and dorsal vertebrae. Indistinct in the latter. The principal use of the deep spinal muscles is to fix the spinal column, and move its several por- tions slightly; they are antagonistic to most of the other muscles attached to the spine. SUPERIOR EXTREMITY. 41 Rectus posticus major, Or. narrow from the spine of the axis; Ins. broad into the inf. occipital trans- verse ridge. Use, to depress the head posteriorly. Rectus posticus minor, Or. narrow from the spine of the atlas; Ins. broad into the occipital bone, be- hind the foramen magnum. Use, to depress the head backwards. Obliquus inf., Or. narrow from the spine of the axis; Ins. narrow, end of the transverse process of the atlas. Use, to rotate the atlas and head on the second vertebrae. Obliquus super., Or. narrow, from the transverse process of the atlas ; Ins. broad into the rough sur- face between the occipital ridges just behind the mastoid process. Use, to bend the head backwards and to one side. SECTION III. Superior Extremity. Immediately beneath the skin and subjacent cellu- lar tissue the muscles of the arms and side of the thorax will be found, covered with a tolerably dense layer of fascia, which descends from a spine of the scapula, the acromion process, and clavicle, to invest them. It is best marked on the inner side of the arm, where it covers the brachial vessels and nerves, and on the ant. surface of the biceps muse. It is firmly attached to the lower margins of the pectoralis major and latis- simus dorsi, and passes from these across the floor of the axilla, so as to close and protect its cavity. In- feriorly, the brachial aponeurosis is attached to the intermuscular septa, and the condyles of the humerus. Muscles of the Shoulder, 5. Deltoideus, Or. 1, from the whole extent of the post. border of the spine of the scapula; 2, the acromion process; 3, the ext. third of the clavicle. Ins. narrow, into a triangular surface on the outer side of the hu- 4* 42 MUSCLES OF SCAPULA. merus a little above its middle, between the two heads of the brachialis anticus m. '.separated from the pec- toralis major by the descending branch of the thor- acic acromialis art. and the cephalic vein. Use, to raise the arm from the side, or to depress the shoulder. The ant. fibres draw it forwards ; the post, backwards. Supra spinatus, Or. the inner two-thirds of the fossa supra spinat.; Ins. super, facette of the larger tuber- cle of the humerus. Use, to raise and abduct the arm. Infra spinatus, Or. inf. surface of the spine, and the dorsum of the scapula as far as the post, of the two ridges on its inf. costa; Ins. middle facette of the larger tubercle of the humerus. Use, to raise the arm, and draw it backwards. Teres minor Or. inf. costa of the scapula, between its two ridges ; Ins. inferior facette of the larger tu- bercle of the humerus. The tendons of these three muscles cover the head of the humerus, and are inti- mately adherent to the capsule of the joint. Use, similar to the preceding. The principal use of the three capsular muscles is to support the articula- tion, and keep the head of the humerus in situ. Teres major, Or. form a flat quadrilateral surface on the inf. angle of the scapula; Ins. post, marghrof the bicipital groove, behind the tendon of the latissi- mus dorsi. Use, to draw the arm downwards, back- wards, and to the side; to rotate it inwards ; and when the arm is fixed, to draw forwards the inf. angle of the scapula, and elevate the glenoid cavity. The two teres muscles, in proceeding to their in- sertions, leave an opening between them, which is divided into two by the passage of the long head of the triceps; the anter. one transmits the post, cir- cumflex artery and nerve; the other the r. dorsalis scapulae of the infra scap. art. and nerve. Subscapularis Or. subcapular fossa and its mar- gins ; Ins. the inner or smaller tubercle of the hu- merus to keep the head of the humerus and glenoid cavity in close apposition. MUSCLES OF ARM. 43 Muscles of the Arm : in front, 3 ; Flexors. Coraco brachialis, Or. from the tip of the coracoid process in conjunction with the short head of the biceps, to which it is attached for some way down; Ins. into the inner side of the humerus, opposite to the insertion of the deltoid ; it first covers and then runs along the outer side of the art. brachial : per- forated by the ext. cutan. nerve. Use, to raise, draw forwards, and rotate the arm outwards. Biceps, Or. the short head, from the tip of the cora- coid process with the coraco brachialis m. ; the long head, from the upper edge of the glenoid cavity where its tendon bifurcates, its division descending on the margins of that cavity to meet similar divisions on the long head of the triceps. Ins. by a strong flat tendon, which is twisted half around, into the tubercle of the radius: just before the tendon sinks to its insertion, it gives on 7 the semilunar fascia, which crosses the pro- nator teres, to strengthen the fascia of the fore arm. . The long head is enclosed in the capsular ligament of the shoulder joint, but outside of the synovial mem- brane, which accompanies it for some way down the groove, -.its inner edge constitutes an unerring guide to the brachial artery. Use, to flex the fore arm on the arm, to make tense the fascia, and rotate the ra- dius outwards; also to depress the glenoid cavity and scapula. brachialis anticus, Or. 1, by two angular slips which embrace the insertion of the deltoid; 2, from the condyloid ridges of the humerus, and anterior sur- face between them, down to the elbow joint. Ins. coronoid process of the ulna, and rough surface be- yond. Use, to flex the fore arm. Back part of the Arm, 1, Extensor. Triceps, Or. 1, its long head, by a flat tendon from the lower edge of the neck of scapula, where itbifur- 44 ARTERIES AND NERVES OF ARM. cates to join the divisions of the biceps; 2, middle head, from the post, and ext. surface of the humerus, between the spiral groove and insertion of the teres minor, and from the ext. condyloid ridge and aponeu- rotic septum, as far as the condyle ; 3, the small head, from the int. and post, surface of the humerus, below the spiral groove and insertion of the teres major m., and from the int. condyloid ridge and intermuscular septum. Ins. by a strong aponeurosis into the olecra- non. -.the spiral groove commences above the small head, winds in front of the long head, and below the super, attachments on the middle head. Use, to extend the fore arm, and depress the neck of the scapula. The long head separates the two spaces beneath the inf. margin of the scapula ; its second and third heads are separated by the musculo spinal or radial nerve. In the dissection of the muscles of the shoulders and arm, numerous vessels and nerves are met with. The arteries are branches of the subclavian, the superior scapular, and posterior scapular ; of the axillary, the thoracica acromialis, thoracica suprema, glandulares thoracica longa or submammary, the subscapular, and the anterior and posterior circumflex ; of the brachial, the superior profunda, inferior profunda, and anastomatica magna. The superior, posterior, and subscapular arteries, as their names imply, surround the margins of the scapula, and sending branches to the muscles on both of its surfaces, anastomose freely together, and thus establish an intimate connexion between the subcla- vian and axillary arteries ; and by no means of their subanastomoses with the carotid arteries above and the brachial arteries beneath, are of essential impor- tance in tying any one of these vessels. The remain- ing branches of the axillary, excepting the circumflex are found connected with the pectoral muscles, and cavity of the axilla ; these anastomose freely also with the vessels about the shoulder externally, and the MAMMARY GLAND. 45 >racic and intercostal arteries internally, as to keep up the circulation when one or other of the large trunks is tied. The circumflex arteries surround the neck of the humerus, and are chiefly lost in the deltoid. The nerves of this region are principally derived from the brachial plexus ; they are anterior and pos- terior thoracic to the thoracic muscles, the circumflex to the deltoid, the suprascapular to the fossa of the same name, the subscapular to the subcap. muscle, and sending a few filaments to the dorsal surface of the scapula, and lastly, the nerves to the arm and fore- arm, viz., on the outer side the ext. cutaneous and median, on the inner the int. cutaneous and ulnar, and posteriorly the musculo-spiral or radial. Some small nervous filaments are met with in the subcuta- neous cellular tissue ; these are chiefly on the inner side, and consists of branches from the internal cuta- neous, and the nerves of Wrisberg, derived from the 2nd and 3rd intercostals. The principal veins are the cephalic and basilic, and the brachial trunk.- The Axilla, or Axillary cavity is triangular, its apex superiorly at the coracoid process; the base infe- riorly formed by the axillary fascia, stretching from thepect. major to the latissimus dorsi; it is bounded in front by the pectoral muscles, behind by the sub- scap. muse., internally by the serratus magnus, ex- ternally by the neck of the hurnerus ; it contains the axillary artery and vein, and their principal branches, and the axillary plexus of nerves, the con- tinuation of the brachial plexus embeded in cellular tissue and a number of lymphatic glands. In the female subject, the Mammary Glands are found one to each side resting on the pectoralis ma- j or muscle to which they are loosely connected by ar eo- lar tissue. The mammary gland is hemispherical in shape, convex in front, flat posteriorly: it is composed of a number of distinct lobules, separated by condensed 46 THE FORE-ARM. cellular tissue, and some adipose substance. Each lobule is composed of a number of granules, from which the lacteal ducts proceed, and gradually uni- ting open upon the free extremity of the nipple. This is a slightly conical projection, composed of the in- teguments, lacteal ducts, and erectile areolar tissue ; it is surrounded by an areole of the integuments, generally of a brownish colour, but in the young fe- male, unimpregnated, is of a pinkish hue; on this open a number of sebaceous follicles. The mammary gland is supplied with blood from the thoracic branches of the axillary, the intercos- tal, and the internal mammary. The nerves are de- rived from the brachial plexus and the intercostals. Its absorbents are very numerous, and communicate with the axillary, cervical, and thoracic glands. SECTION IY. Of the fore-arm. The fore-arm extends from the elbow to the wrist- j oint ; it is covered by the integuments, beneath which lies a quantity of loose cellular tissue in which are found in front, the superficial veins viz., the cepha- lic on the outer, the basilic on the inner side, and median in the centre, and superficial nerves branches of the int. and ext. cutaneous ; on the back part, also, some superficial veins and nerves, the latter branches of the ext. cutaneous and musculo-spiral nerves. Beneath this is the ant. brachial aptneuratis, or fascia, exceedingly dense, investing the muscles, and sending septa between so as to separate them from each other ; it is attached superiorly to the condyles of the humerus, intermuscular septa and tendon of the biceps, on the inner side to the spine of the ulna, and inferiorly to the ant. and post, annular ligaments of the wrist. MUSCLES OF TORE-ARM. 47 Muscles of the Fore Arm, in front, 8. Superficial set, 5, which arise from the inner condyle. Pronator teres, Or. 1, the inner condyle and inter- muscular septa; 2, from the coronoid process of the ulna. Ins. outer edge of the radius, at its middle.'. The median nerve passes between its two origins. Use, to flex the fore arm, and rotate the radius inwards. Flexor carpi radialis, Or. inner condyle and septa; Ins. base of the second metacarpal bone. Use, to flex the fore arm and hand. Palmaris longus, Or. inner condyle and septa; Ins. annular ligament and palmar fascia. Use, to make tense the palmar aponeurosis and flex the hand. Flexor carpi ulnaris, Or. 1, inner condyle; 2, inner edge of the olecranon; 3, by an aponeurosis from the upper two-thirds of the inner edge of the ulna. Ins. pisiform bone, its fibres strengthening the ligament which unites that bone to the os pyramidale. -.the ul- nar nerve passes between the first and second origins: its inner edge is a guide to the lower two-thirds of the ulnar artery. Use, to flex the hand. Flexor sublimis perforatus, Or. 1, inner condyle; 2, the inner edge of the coronoid process of the ulna; 3, upper part of the oblique ridge of the radius. Ins. into the fingers by four tendons, which split at the end of the first phalanx, to give passage to the tendons of the deep flexor; each division then winds round the edges of the corresponding tendon of the latter muscle, so as to form a kind of sheath for it, and both are then inserted close together into the fore part of the second phalanx. Use, to flex the fingers on the hand, and this on the wrist. Deep seated Muscles, 3. Flexor profundusperforans, Or. 1. ant. three-fourths of the fore part of the ulna and inner edge of the coro- noid process; 2, inner half of the interosseous liga- 48 MUSCLES OF FORE-ARM. ment; 3, by a slip from the radius, just below its tu- bercle. Ins. by four tendons, each of which perfo- rates a corresponding tendon of the last m., and is inserted into the last phalanx. Use, to flex the fin- gers on the hand, and this on the wrist. Flerxo longus pollicis Or. 1, ant. surface of the ra- dius, from its tubercle to the upper edge of the pro- nator quadratus ; 2, outer half of the interosseous ligament, Ins. last phalanx of the thumb. Use, to flex the thumb. Pronator quadratus Or. lower fifth of the anterior surface, and inner edge of the ulna ; Ins. ant. surface and inner and outer edges of the lower fourth of the radius. Use, to pronate the radius and hand. Muscles on the outer edge, 4. Supinator radii longus, Or. ext. conclyloid ridge of the humerus and intermuscular septum, from the spiral groove to within two inches of the condyle ; Ins. into the styloid process of the radius.*. the lower two thirds of the radial artery run along the inner edge of its tendon. Use, to supinate the hand. Extensor carp, radialis longior, Or. from the lower part of the external condyloid ridge, and the external condyle ; Ins. post, surface of the carpal end of the second metacarpal bone. Ext. carp. rad. brevior, Or. post, part of the exter- nal condyle, with the common extensor: Ins. post, sur- face of the carpal end of the third metacarpal bone. Supinator radii brevis, Or. 1, from the outer condyle by the common tendon ; 2, from the ext. lateral and annular ligaments : 3, from a ridge on the ulna and triangular fossa in front of it. Ins. into the fore-part, and outer and back part of the radius, in a line lead- ing obliquely from above its tubercle to the ins. of the pronator teres. Pierced by the posterior branch of the spiral nerve : the biceps tendon passes through the fibres of the muscle where they cover the tuber- MUSCLES OF FORE-ARM. 49 lie of the radius. The use of these muscles is indi- cated by their names. Muscles on the back of the Fore-Arm. Superficial set, 4. Extensor digitorum communis, Or. 1, by a tendon, which it shares with the ext. carp. r. b., ext. carp, uln., and ext. min. digit., from the ext condyle; 2, from the intermuscular aponeuroses. Ins. into the phalanges by four tendons, each of which first sends off an expansion from its edges to cover the dorsum of the first phalanx, and then, dividing into three slips sends one to the upper end of the second phalanx, and one on each side of the first joint to the upper end of the last phalanx ; the three ext. tendons are united by transverse slips, before they reach the phalanges. Extensor minimi digiti, Or. from the outer condyle by the common tendon ; Ins. back part of the phalan- ges of the little finger, like the corresponding tendon of the common extensor. Extensor carpi ulnaris, Or. 1, outer condyle by the common tendon; 2, post, surface and outer edge of the ulna ; Ins. back part of the carpal end of the fifth metacarpal bone. The uses of the preceding mus- cles are indicated by their names. Anconseus, Or. by a distinct tendon from the miter condyle ; Ins. 1, into the outside of the olecranon where it is continuous with the triceps ; 2, triangular surface on the upper fourth of the ulna. Use, to extend the fore-arm. Deep-set, 4. Extensor metacarpi pollicis, Or. from the ulna, in- terosseous ligament, and radius, just below the su- pin. brevis muscle; Ins. back part of the carpal end of the first metacarpal bone. 5 50 ARTERIES OF FORE-ARM. Extensor primii nternodii, Or. 1, radius and inte- rosseous ligament below the last m.; 2, slightly from the ulna. Ins. back part of the carpal end on the first phalanx. Extensor secundi internodii, Or. broad from the mid- dle third of the back of the ulna, and slightly from the interosseous ligament. Ins. back of the carpal end of the second phalanx. The use of the prece- ding muscles is indicated by their names. Indicator, ?)/\Jgfick part of the ulna and interros- seous ligamentTbeLow the la^t muscle; Ins. by slips into the phalanges of the index finger, like the common ext. -ff^p^tD^extend the forefinger, as in pointing. ~__ ^~ -^" In the dissection-eftliG-muFcles of the fore-arm, the vessels and nerves of this region are exposed. The arteries are the radial, ulnar, and interosseous. The radial artery proceeds from the bifurcation of the brachial art. opposite the coronoid process of the ulna, along the outer and ant. surface of the fore- arm, at first deep but inferiorly superficial, and then winds around the* ext. lat. lig. of the wrist to pass between the first and second metacarpal bones into the palm of the hand. Its principal 'branches are the radial recurrent, and superficialis volae ; the rest are muscular branches. The ulnar art. lies on the inner and ant. surface of the fore-arm, and like the preceding, becomes more superficial near the wrist; it here passes above the annular lig. and enters the palm of the hand. Its principal branches are the ant. andpost. ulnar, recur- rent anfl interosseous; the rest are chiefly muscular. ~* The inferosse&HS art. is a branch of the ulnar; it sinks deep, lies on the interosseous membrane, and terminates in the pronator quadratus muscle. Its principal branch is the post, interosseous, which passes to the back of the fore-arm between the ant. oblique lig. and the interosseous membrane. THE HAND. 51 The nerves met with in the fore-arm are the muscu- lo-spiral, or radial, ulnar and median. The mu sculo- spiral, or radial nerve, joins the radial at the junction of the upper and middle thirds of the fore-arm, runs along its outer side, and at the junc- tion of the middle and lower thirds winds around the radius beneath the supinator longus tendon to the back of the wrist and hand; a little beneath the elbow it sends off its largest branch, which perforates the supinator brevis to supply the muscles on the back of the fore-arm. The ulnar nerve accompanies the ulnar art. on its inner side, and enters with it the palm of the hand ; its principal branch proceeds from it some distance above the wrist, and bends round the ulna to the back of the wrist and hand. The median nerve accompanies the brachial art., sinking into the fossa beneath the elbow, passes be- tween the two heads of the pronator quadratus, de- scends to the wrist, where it lies behind the palmaris longus tendon, and enters the palm of the hand, be- neath the annular lig. The deep-seated veins are the venae comites, two of which accompany each art., lying on either side; they unite generally at the elbow to form the brachial vein, although the basilic frequently joins the rest above the joint. SECTION V. Of the Hand. Beneath the integuments of the palm of the hand and a quantity of adipose tissue, lies the palmar apo- neurosis, or fascia. This is exceedingly dense; trian- gular in shape, it proceeds posteriorly from the ant. annular lig. forwards and divides into four fasciculi, each of which subdivides into two, to allow of the passage of the flexor digitorum tendons, the digital 52 MUSCLES OF THE HAND. vessels and nerves, and pass to be inserted into the lateral ligaments of the metacarpo-phalangeal articu- lations. Beneath this lie the muscles, vessels, and nerves, with the exception of the palmar brevis, which lies superficial to it. Muscles of the hand, 19. Those on the outer edge, 4. Abductor pollicis, Or. from the scaphoid bone and annular ligament of the carpus; Lis. with the outer head of the short flexor. Opponens pollicis, Or. from the trapezium and an- nular ligament: Ins. whole length of the outer edge of the metacarpal bone. Flexor brevis pollicis, Or. by two. portions, 1, from the trapezium, lower edge of the annular ligament, and sheath on the flex, carp, rad. m. ; 2, from the os magnum. Ins. by two heads, each enclosing a sesa- moid bone, into both sides of the first phalanx, with abductor on one side, and the abductor m. on the other. Abductor pollicis, Or. the whole length of the ant. surface of the third metacarpal bone; Ins. with the in- ner head of the short flexor. The use of these mus- cles is indicated by their name. Muscles on the inner edge, 4. Palmaris brevis, quadrilateral Or. annular ligament and inner edge of the palmar fascia ; Ins., its short parallel fibres are lost in the skin over the inner edge of the hand. Use, to corrugate the integ., on the in- ner side of the hand. Abductor minimi digiti, Or. pisiform bone; I/is, in- ner edge of the base of the first phalanx. Flexor brevis, d. minimi, thin when it exists, Or. lower edge of the carpal annular lig. and unciform RELATIONS. 53 process is soon identified with the former. The ulnar art. and nerve separate them at their origins. Opponens dig. minimi, Or. the same as the short flexor; Ins. whole length of the inner edge of the fifth metacarpal bone. The use of these muscles is indi- cated by their names. Muscles in the middle of the Hand, 11. Lumbricales, Or. fore and outer parts of each ten- don of the flexor profundus; Ins. with the correspond- ing interossei into the edge of the dorsal expansion on the same side. Use, to assist the flexor tendons, or to act with them. The interossei. If the median line or axis of the third metacarpal bone be taken as a fixed point, the palmar int erossei may be considered as adductors, and the dorsal as abductors , both sets arise from the op- posite edges of two metacarpal bones and are inserted into the edges of the dorsal expansion. The dorsal interossei, four in no., are attached, the first, or indi- cator, to the radial edge of the index finger, the se- cond, to the radial edge of the medius, the third to the ulnar edge of the medius, and the fourth, to the ulnar edge of the ring finger. The palmar interossei, three in no., are attached, the first, to the ulnar edge of the index, the second, to the radial edge of the ring finger, and the third, to the radial edge of the little finger. The relations of the parts about the wrist-joint are as follows. A. Back of the joint, 1, styloid process of the radius and ins. of the supinator longus, covered by the tendons of ext. metacarpiet primiinternodiipol- licis; 2, the tendon of the ext. secund. internodii. In their triangular interval between this m. and the two latter, may be felt the radial artery just before it passes between the metacarpal bones, and the tendons of the two radial; extensors; 3, the tendon of the ex- ten, indicis, those of the common extensor, and that 5* 54 VESSELS AND NERVES OF HAND. of the exten. min. digit! ; 4, the extensor carpi ulna- ris, and thestyloid process of the ulna. B. Forepart of the joint, commencing at the same point, 1, surface of the radius, supporting the radial artery ; 2, tendon of the flexor carpi radialis, and immediately beneath it that of the flexor proprius pollicis; 8, tendon of the palmaris longus, the tendon of the flexor profundus being felt in the interval ; 4, flexor carpi ulnaris and pisiform bone, the tendons of the flexor sublimis sup- porting the ulnar artery and nerve in the interval. The median nerve passes under the annular ligament, imbedded in the flexor tendons, and at the ulnar edge of the flexor c. radialis. The arteries and nerves me\ within the palm of the hand are the superficial and deep palmar arches. The superficial palmar arch of arteries lies immedi- ately beneath the palmar aponeurosis; it is formed by the ulnar art. and superficialis voloe branch of the ra-* dial, and supplies three and a half fingers, counting from the little finger. The superficial palmar arch of nerves accompanies ' this, lying beneath it ; this is formed by the median nerve, and supplies three and a half fingers, counting from the thumb, the remaining finger and a half being supplied by the ulnar nerve. The deep palmar arch of arteries and nerves lies be- neath the flexor tendons on the interossei muscles; the first is formed by radial art. with the deep branch of the ulnar ; it supplies one finger and a half count- ing from the thumb ; the latter is formed by the deep branch of the ulnar, and is lost chiefly in the interossei muscles. 55 CHAPTER IV. THE TRUNK is composed of two large cavities, the thorax and ab- domen, each of which contains important viscera, most of these belonging to the organic life of the individual. The pelvis assists in forming the trunk inferiorly. It will be described with the lower extremities. SECTION 1. The Thorax is a large conical cavity giving lodgment to and pro- tecting the great central organs of respiration and cir- culation, namely, the lungs, heart, aorta, pulmonary artery, vena cava, thoractic duct, &c. It is formed by the twelve dorsal or thoracic vertebras posteriorly; the ribs posteriorly, laterally, and in front; the sternum and costal cartilages anteriorly ; its apex is truncated, and forms an oval aperture superiorly, bounded by the first dorsal vertebra posteriorly, the first rib la- terally, and the upper end of the sternum and first costal cartilage in front ; through this pass upwards the sternohyoid. sterno thyroid, andlonguscolli mus- cles; the arteria innominata, left subclavian, and ca- rotid arteries ; cone of the pleura, right and left re- current nerves, and thoracic duct ; downwards, the vense innominates, internal mammary, and superior in- tercostal arteries; pneumogastric, phrenic, recurrent and sympathetic nerves, trachea, and oesophagus. The base of the thorax is formed inferiorly by the dia- phragm; through this pass the aorta, inferior vena cava, and venaazygos, pneumogastric, phrenic, splan- chnic, and sympathetic nerves, oesophagus and tho- racic duct. The perpendicular diameter is greatest posteriorly and laterally, least anteriorly; the trans- 56 ANTERIOR MEDIASTINUM. verse is greatest inferiorly, least superiorly; the antero posterior is greatest inferiorly from the lower end of the sternum backwards to the spine. The THORACIC CAVITY is divided into five compart- ments by the reflexion of the pleura, of these two are on the mesial lines, the anterior and posterior medi- astinum; one, on the left side, the pericardium, and two laterally the pleura cavities for the lungs. Thepleura is a serous membrane which lines most of the interior of the thorax, one on each side, each being distinct from the other, so as to form two sepa- rate membranes. The right is the larger but shorter. Each pleura passes upwards into the neck as high as the fourth cervical vertebra, forming its cone ; in- feriorly it lines the upper surface of the diaphragm, and here forms the ligamentum latum pulmonis ; in- termediately it is reflected in the following manner; from about the junction of the sternum and costal car- tilages it passes outward, lining the inner surface of the ribs, until it reaches to the side of the dorsal ver- tebra; it here turns forward, forming the side of the posterior mediastinum, and passes outwards on the post, surface of the root of the lungs, lines these or- gans, passing in between their lobes, round the ant. surface of the root of the lungs, then lines the lateral surface of the pericardium, from which it approaches its fellow of the opposite side, passes forwards and outwards, forms the lateral boundary of the anterior mediastinum, and arrives at the junction of the ster- num and costal cartilages. The pleura is divided as it lines the lungs or ribs into the pleura pulmonalis and costalis; the latter is the stronger of the two* The anterior mediastinum inclines downwards and a little to the left side ; it extends from the upper to the lower extremity of the sternum, triangular in shape, its base turned forwards is formed by the post, sur- face of the sternum and a little by the costal cartilages, its apex turned backwards is formed by the conver- STRUCTURE OF LUNGS. 57 gence of the pleura}, which bound it laterally; it is slightly contracted in the centre. Its contents are the thymus gland, the triangularis sterni muscles, and the int. mammary arteries. The thymus gland is largest in the foetus, when it nearly fills the ant. mediastinum; it consists of two lobes, divided by an oblique fissure. Its use is wholly unknown. In the adult it degenerates into cellular tissue. The lungs are the great organs of respiration. Each lung is conical in shape, and corresponds to the pleu- ral cavity ; the apex fits into the cone of the pleura ; its base, concave, rests on the upper surface of the diaphragm; its anterior surface, concave, is applied against the pericardium; the outer and posterior sur- faces are convex. The right lung is the larger but shorter, and consists of three lobes; the left has but two lobes. These lobes are separated by the great fis- sure which runs obliquely downwards and forwards, so as to divide each lung into an interior smaller, and a post, larger lobe; from the middle of the fissure pro- ceeds a small fissure on the right side, cutting oif the third from the superior lobe. The root of the lung is formed by an assemblage of the several structures entering or leaving the organ viz., the bronichial tube, pulmonary art., and pulmo- nary veins, surrounded by cellular tissue, and covered by the pleura. The order of parts in each lungis from behind forwards, bronchus, artery, veins; from above downwards, on the right side, bronchus, art., veins: on the left, art., bronchus, veins; these are enveloped by the pulmonic plexus of nerves, best marked on the posterior surface, and formed by the pneumogastric and sympathetic nerves . A number of dark-coloured glands, bronchial glands, are found around the root of each lung. The structure of the lungs is composed of bronchial tubes and air cells, pulmonary arteries and veins united by fine areolar tissue, I 58 PULMONARY PLEXUS. The bronchial tubes are the continuation of the trachea, from the bifurcation of which, opposite the second dorsal vertebra, they descend obliquely down- wards and outwards to the root of each lung. The right bronchus is less oblique than the left; it passes behind the superior cava to the root of the lung; the left bronchus passes through the arch of the aorta, in front of the thoracic aorta, to the root of its lung. The bronchial tubes divide into numerous branches, which ultimately terminate in forming the air cells, which form a slight expansion resembling a cluster of grapes. A bunch or cluster of the air cells form the lobules, and these united form the lobes. These lo- bules are united by fine areolar tissue, the interlobular cellular tissue, in which the pulmonary arteries and veins run to their destination. The structure of the bronchial tubes is the same as that of the trachea, except in their small branches and air cells, which want the cartilaginous structure. The structures of these consist of an internal lining mu- cous membrane, an ext. cellular coat, and a thin layer of muscular fibres between: some deny the existence of these. The pulmonary arteries enter the lungs at their root, and divide the right into three, the left into two branches, to supply the lobes ; they gradually break down into capillary vessels, which ramify on the outer surface of the air cells, and so conduct the black blood to be oxygenated by the atmospheric air. The pulmonary veins arise from the capillaries of the pulm. art., and unite on each side into two large ves- sels, which cross inwards, and open into the posterior surface of the left auricle of the heart; and thus con- duct the art. blood info this organ. The right are longer and larger than the left. The pulmonic plexus sends its numerous filaments along the posterior surface of the bronchial tubes to their minutest ramifications, and finally terminates in the air cells. THE TRACHEA. 59 The absorbents of the lungs are numerous, and ter- minate in the bronchial glands. The bronchial arteries are small vessels which arise from the thoracic aorta to supply the lungs with nu- trition. Their blood is returned by the bronchial veins. There is a free anastomosis between them and the pulmonary vessels. The lungs in the healthy adult are of a mottled gray colour, are light and spongy ; in the young sub- ject, after breathing, they are of a reddish colour, be- fore breathing are dark red; in the diseased state they are frequently nearly black, from a deposit of carbon in their structure. The lungs are light and spongy, and float in water. The trachea descends from the termination of the larynx, opposite about the fourth cervical vertebra, downwards and a little to the right side of the mesial line of the neck, enters the cavity of the thorax be- tween the ant. and post, mediastinum, and divides opposite the second dorsal vertebra into the right and left bronchial tubes. In the neck, the trachea is covered in front by the sterno hyoid and thyroid muscles, and partly by the thyroid gland ; it rests posteriorly on the oesophagus, which inclines to its left side; on each side of it is the carotid sheath and contents, the recurrent and sym- pathetic nerves. In the thorax it is crossed by the thymus gland, and left vena innominata, and sup- ports the upper part of the arch of the aorta. The phrenic, pneumogastric, and sympathetic nerves de- scend to its outer side, and behind it is the oesophagus and spinal column. The -right vena innominata de- scends on its right side, the thoracic duct ascends on its left side, but post, to it. The structures of the trachea consist of cartilaginous rings, fibrous tissue, mucous membrane, and muscu- lar fibres. The tracheal rings form but three parts of -a circle, being deficient posteriorly. They are from 60 VENA AZYGOS. eighteen to twenty in number, and vary in size ; the first is the largest ; they are connected by fibrous mem- brane. The trachea is completed posteriorly, where the rings are deficient, by three layers of tissue, the ext. isfibrous, some consider elastic; the next is trans- verse muscular fibre: and the internal is the lining mucous membrane ; between these are some small glands which open on the mucous membrane. The pericardium and heart occupy the middle me- diastinum, and will be found under the head of the Vascular System. The posterior mediastinum extends nearly on the me- sial line in front of the spine, from the second or third to the tenth dorsal vertebra, triangular in shape, its apex, turned forwards, is formed by the convergence of the pleurae, its base backwards by the spinal co- lumn; its contents are, the oesophagus and thoracic aorta to the left side, the vena azygos to the right, the thoracic duct in the centre, the splanchnic nerves are found in its lower part. The oesophagus descends from the pharynx to the left side behind the trachea, through the arch of the aorta, crosses a little in front of the thoracic aorta, perforates the diaphragm, and terminates in the car- diac extremity of the stomach: on its surfaces are found, a little above the diaphragm, the pneumogas- tric nerves, the left being anterior. The oesophagus is composed of longitudinal muscular fibres, lined by mucous membrane ; some circular fibres are described at its cardiac extremity, but their existence in the human subject may well be questioned. The thoracic aorta lies to the left side of the spine, but inferiorly comes forward in front, and enters the abdomen through the aortic opening. The vena azygos is formed by the junction of the lumbar veins in front of the second lumbar vertebra ; it ascends through the aortic opening of the diaphragm, passes upwards in the posterior mediast, to its right THORACIC DUCT. 6T side, and finally hooking round the root of the right lung, terminates in the sup. vena cava: in this course it receives the eight or nine inferior intercostal veins, and generally the left vena azygos, which crosses from the left side behind the aorta to join it; this is formed by the six inf. intercostal veins of the left side ; the remaining intercostal veins form the superior inter- costal veins, and terminate in the right vena inno- minata ; the left receives the superior six intercostal veins on its side, and terminates in the left vena inno- minata. The thoracic duct is the trunk of the absorbent sys- tem ; it is formed in front of the third lumbar vertebra by the junctions of the lymphatics from the lower ex- tremities and pelvis, and passes upwards in front of the spine; it escapes from the abdomen through the aortic opening of the diaphragm, between the aorta to its left and the vena azygos to its right side, enters the post, mediastinum, ascends on the mesial line of the spine, inclines to its left side, passes behind the arch of the aorta, and ascends into the neck, behind the left carotid and int. jugular vein, as high as the sixth cer- vical vertebra ; it now turns downwards and inwards, and terminates in the left subclavian vein near its junction with the int. jugular. In its course the thoracic duct occasionally divides into two or more branches, which unite again into one trunk. Its structure consists of two coats, an exter- nal fibrous and an internal serous, which is thrown into numerous folds forming valves. There is generally a small thoracic duct on the right side, which conveys the absorbents from the right side of the head and neck and right arm into the right sub- clavian vein. The splanchnic nerves are formed from the last six dorsal ganglia of the sympathetic ; they perforate the diaphragm, and terminate in the semilunar ganglion and renal plexus. 6 62 THE ABDOMEX. SECTION II. The Abdomen, the largest cavity in the human body, is bounded above by the diaphragm, below by the pelvis, behind by the lumbar vertebrae and quadratus lumborum mus- cles, laterally and in front by the abdominal muscles. Unlike the thorax, its parietes are chiefly muscular, and thus exert a necessary pressure on the abdominal viscera. The abdomen is divided, for the purposes of descrip- tion, into three principal regions, namely, the upper or epigastric, the central or umbilical, and the inferior or hypogastric. A line drawn from the inferior edge of the costal cartilages across to the opposite side se- parates the two superior, and a similar transverse line drawn between the ant. sup. spinous processes of the illium separates the two inferior; each of these regions is further subdivided into three by thelineae semilunares, which extend from the cartilages of the eighth or ninth rib down wards and inwards towards the pubis. The epigastric thus consists of a central, or epiga^- tric region, and a right and left hypochondriac; the umbilical of a central umbilical and a right and left lumbar ; and the hypogastric of a central hypogastric and a right and left iliac region. The lower portion of this region is further subdivided into a central pubio and a right and left inguinal region. Anterior and Lateral Muscles of the Abdomen, 5. Obliquus externus, Or. the eighth or ninth infer, ribs by fleshy digitations, of which five intersect with the serratus magnus, and three or four with the latissi- mus dorsi; Ins., 1, fleshy into the ant. two-thirds of the crista ilii ; 2, the rest of the muscle ends at a line from the ant. sup. spinous p. to the ensiform cartilage MUSCLES OF THE ABDOMEN 63 in an aponeurosis, by which it is ins. into the wiiole length of the linea alba, the lower portion c ithis aponeurosis (Poupart ligament) extends from the ant. sup. spin. p. across the femoral vessels to be ins. by one slip (int. pillar of the ext. ring) into the sym- physis pubis, by another (ext. pillar of the ext. ring) into the spine of the pubis; 3, by a broader portion ( Gimbernat's ligament,) which is folded under the cord, presenting a sharp lunated edge towards the femoral vessels, into the spine of the pubis, and an inch along the pectineal line .. tht reflected portion of the apo- neurosis forms the ant. and inf. walls of the inguinal canal .-. a space exists between its post, edge and the ant. edge of the latis. dorsi m. which has been the seat of hernial protrusion, (Petit.) Use, to depress the ribs and compress the abdominal viscera, to raise the pelvis if the thorax be fixed, or to depress them forwards if the pelvis be fixed. Obliquus internus, Or. 1, from the fascia lumborum ; 2, ant. two-thirds of the crista ilii ; 3, from the ext. two-thirds of the grooved or internal surface of Pou- part's ligament. Ins. the upper portion, fleshy into the edges of the four inf. costal cartilages; the middle terminates at the linea semilunaris in the middle ab- dominal aponeurosis, by which it is continued to the linea alba ; the portion from Poupart' s ligament (with the lower fibres of the transversalis) arches over, and then behind, the cord (Cooper,) to be ins. 4nto the body of the pubis, behind the ext. ring, and into the pectineal line . . the last portion, with the transver- salis, forms the upper and posterior walls of the ing. canal. (Fascise.) Use, nearly similar to the preceding; it rotates the trunk in the opposite direction, and thus co-operates with the ext. obliquus of the other side of the body. Cremaster, Attachments, 1, ext. two-thirds of Pou- part 1 s ligament; 2, behind that ligament at its pubic attachment ; the intervening fibres descend in succes- 64 MUSCLES OF ABDOMEN. sive loops to be ins. into the cord, and to surround the tunica vaginalis, so as to sling the testicle .. the testicle, in its passage beneath the lower edge of the obliquus int. m., draws down with it the muscular fibres to form the cremaster (Cloquet ; ) the cord passes between the lower fibres of the transversalis, from which also the muscle is derived. (Guthrie.) Use, to suspend the testis. Transversalis, Or. 1, ext. two-thirds of Poupart's ligament; 2, ant. three-fourths of the crista ilii; 3, fascia lumborum ; 4, inner surfaces of the six lastribs, by digitations, which intersect with the diaphragm. Ins. the upper part terminates at the linea semiluna- ris in the post, aponeurosis, by which it is continued to the linea alba : that from Poupart's ligament passes over and behind the chord to be ins. with the int. obliq. into the pubic end of Poupart's ligament and ilio pectineal line. Another portion passes behind and then under the cord, in front of the fascia trans- versalis, to Poupart's ligament; thus forming the poster, and part of the inf. wall of the inguinal canal. (Cooper.) Use, to assist the obliq. muscles in respi- ration and the compression of abdm. viscera. Rectus Abdominis, Or. by a double tendon from the pubis, between its spine and symphysis; is ins. by three portions: 1, ensiform cartilage and costo xiphoid lig.: 2, fifth costal cartilage; 3, sixth and seventh costal cartilages .-. The muscular fibres are partially interrupted by three or four zigzag tendinous inter- sections which adhere to the forepart of the sheath. Use, to approximate the pelvis and thorax. Pyramidalis, triangular, sometimes absent, Or. by its base, from the pubis and ant. pubic ligament. Ins. by its apex into the linea alba, sometimes as high as half-way towards the umbilicus. Use, to assist the preceding. These muscles are enclosed in a fibrous sheath, formed by the tendons of the obliquus and transver- THE DIAPHRAGM. 65 sails muscles. This sheath extends from the xiphoid and costal cartilages superiorly, to the crest of the pubis, into which it is implanted; it is formed by the ext. oblique tendon, and one layer of the int. oblique passing in front of the rectus muse, and behind by the second layer of the int. obliquus and transversalis, except from half- way between the umbilicus and pubis to this bone, where the whole of the tendons pass in front of the rectus; this muscle is intersected by three or four irregular transverse lines: the lineoe trans- versse one at the umbilicus, one at the xiphoid carti- lage, one between these, and one sometimes beneath the umbilicus. By this intersection each portion of the muscle may act independently of the rest. In the sheath behind the muscle the epigastric art. ascends to anastomose with the int. mammary. The linese semilunares are the oblique lines on the outer edge of the rectus, formed by the junction of the oblique and transversalis tendons. The linea alba is the tendinous white line which extends from the xi- phoid cartilage superiorly to the pubes inferiorly ; it is formed by the intermingling of the fibres of the ob- lique and transversalis muscles, is thinner and wider above than below the umbilicus, where it is particu- larly dense. Post. Abdominal Muscle. Quadratus Lumborum, Or. ileo lumbar lig. and two inches of the crista ilii; Ins. 1, lower edge of the in- ner half of the last rib ; 2, by four processes into the four upper lumbar transverse processes . . enclosed in a sheath like the rectus ; vide, Fascise. Use, to draw down the ribs. Superior Abdominal Muscle. Diaphragm. A moveable septum between the tho- racic and abdominal cavities, composed of a central tendinous portion, surrounded by muscular fibres. The tendon is trilobate, and placed nearly in the cen- 6* 66 THE DIAPHRAGM. tre of the muscle; above, it supports the heart being in the adult firmly united to its fibrous pericardium : below, it covers the centre of the liver. The middle and largest lobe is behind the xiphoid cartilage; the right, the next in size, and the left, the smallest, are directed backwards and outwards on each side. The post, margin of the tendon is notched, and gives at- tachment to the fixed portion of the muscle ; the ante- rior edge, from which the anterior or moving portion, arises, is convex and concentric with the infr. margin of the thorax; Or. posterior or fixed portion; 1, the crura. The left crus arises narrow tendinous from the bodies and intervertebral subs, of the three upper lumbar vertebrae; the right, which is more in front, arises from the corresponding vertebrae, and the in- tervertebral substance next beyond. Opposite the first lumbar vert, they become fleshy, and divide into two portions, which are separated by the splanchnic nerves; the outer portions, arems. into the post mar- gin of the tendon : the inner decussate in front of the vert. col. to form the aortic opening, diverge to form the oesophageal opening, and then pass on to the cen- tral tendon. 2, Another portion arises from the false and true ligam. arcuata on each side to be inserted into the remainder of the notch. The ant. portion, Or. from the whole of the convex edge of the tendon Ins. base of the xiphoid cartilage, and by six or seven digitations into the inner surfaces and upper edges of the six last ribs, where it intersects with the m. trans- versalis. The edge of the aortic opening is tendinous; it transmits the aorta, vena azygos, and thoracic duct; the cesophageal opening is muscular; it transmits the oesophagus and the vagus nerves. The opening for the vena cava is tendinous quadrangular, and tubu- lar, and is placed at the junction of the right and middle lobe of the tendon . . The cellular tissue of the mediastinum, and that between the ant. abdominal THE PERITONEUM. 67 muscles, communicating through an opening on each side of the xiphoid cart. SECTION III. The Abdominal Viscera. The abdomen contains the organs of digestion viz. : the stomach and intestines, the liver, pancreas, and spleen, and in addition, the kidneys, supra-renal cap- sules, and ureters; the abdominal aorta, inf. vena cava, vena porta, thoracic duct, and numerous lym- phatic vessels and glands, the sympathetic nerve, and several smaller vessels and nerves. The abdomen is lined internally by the Peritoneum ; this is the largest serous membrane in the body, and lines the inner surface of the abdominal parietes as well as most of the contained organs. The reflections of the peritoneum may be traced as follows from the umbilicus it passes upwards, lining the inner surface of the tranversalis and recti mus- cles, to the lower margin of the thorax ; it here bends backwards, lining the inf. concave surface of the dia- phragm, sinking deep into the hypochondriac region; on the left it is reflected on the back part of the sple- nic vessels, to the post, surface spleen, it winds round and invests this organ, then passes on the ant. surface of its vessels ; in the centre it is reflected on the stomach so as to enclose this organ, and pass from its margin downwards to form the gastro colic omen- turn ; on the right side it is reflected from the umbili- cus, enclosing the umbilical vein, and forming the suspensory ligament of the liver ; it invests this organ, and passing from its inferior surface encloses the he- patic vessels, and forms the gastro-hepatic fold or omentum; from the diaphragm the peritoneum de- scends on the liver, and forms the lateral ligaments of this organ ; from the convex or inferior border of the stomach the two layers of peritoneum unite to form the gastro-colic ornentum, which passes downwards in 68 THE PERITONEUM. front of the transverse arch of the colon, descends lower on the left than on the right side, becomes re- flected on itself, so as to consist of four layers ; the two posterior layers ascend until they reach the trans- verse colon; they here separate so as to enclose this intestine, and from its concave margin unite and de- scend to form the transverse meso colon ; opposite the duodenum this fold separates into an ascending and descending layer, enclosing the inferior portion of this intestine ; the ascending layer passes in front of the lower and middle portions of the duodenum and of the pancreas to the posterior surface of the right lobe of the liver, where it is continuous with the peritoneum lining this organ and the posterior layer of the lower or gastro-hepatic omentum; the descending layer passes downwards into the lumbar region, where it becomes continuous with the right and left meso co- lon ; in the centre the inferior layer of the transverse meso colon passes in front of the spinal column and the large blood-vessels resting upon it, and is thence reflected downwards and forwards so as to enclose the small intestines and the mesenteric vessels and form the mesentery. Inferiorly the peritoneum descends from the umbi- licus in the centre, enclosing the urachus, and form- ing a slight projection, it then descends, lining the posterior surface of the rectus muscle to near the pubes; it than passes backwards, sinks into the pel- vis, lines the upper posterior and part of the lateral surface of the bladder as low down as near to the pos- terior extremity of the vesiculse seminales and pros- tate gland, whence it is reflected on to the anterior surface of the rectum and the sides of the pelvis form- ing the posterior and lateral false ligaments of the bladder; the peritoneum now ascends, investing the middle and upper thirds of the rectum, forming the meso rectum, whence it passes on each side to line the jliac fossae, and becomes continuous with that lining he abdominal parietes. In the female the peritoneum THE STOMACH. 69 is reflected from the posterior surface of the bladder on the upper and back part of the vagina, whence it passes upwards on the uterus so as to invest this, and form on each side the broad ligaments of this organ, and from it passes upon the rectum as in the male subject. On either side the peritoneum covers par- tially the caecum and signoid flexure of the colon, and binds them down in the iliac fossa. On each side of the mesial line inferiorly, the peri- toneum is thrown into an oblique fold by the degene- rated umbilical artery, and thus are formed the ingui- nal pouches one on each side of the umb. art. The peritoneum in the female does not form a shut sac, as an opening exists in it, where it covers the fimbriated extremities of the Fallopian tubes; here the serous and mucous membranes are continuous. The principal folds formed by the peritoneum are: The gastro hepatic, or lower omentum, consists of two layers, and extends from the transverse fissure of the liver to the concave margin of the stomach ; it contains between its layers the hepatic art. to the left side ; the ductuscholedochus to the right, and the venaporta behind and between both ; these are surrounded by cellular tissue, and form the capsule of Glisson, behind which is the foramen of Winslow leading into the great bag of the omentum. The gastro colic, or great omentum, the meso cxlon, meso rectum, and mesentery have been already suffi- ciently described. The great bag of the omenturn ex- tends from the foramen of Winslow to the bottom of the great omentum; it is bounded in front b} r the lesser omentum, the stomach, and the descending layer of the great omentum; and posteriorly by its ascending layer. The hollow viscera of the abdomen consists of the stomach, the small and large intestines. The STOMACH, the principal organ of digestion, is situated in the left hypochondriac and epigastric re- gions ; it extends from its cardiac or oesophageal ex,- 70 ARTERIES OF STOMACH. tremity downwards and forwards, and near its pyloric extremity turns a little upwards and backwards; it is curved and irregular in shape, and has two orifices, two curves, and two extremities. The cardiac orifice communicates with the oesopha- gus, and is nearly circular; itspyloric orifice is situ- ated towards the right side, anterior to the cardiac; it is also circular, and communicates with the duode- num; the left, or great bulging extremity of the sto- mach, lies in front of the spleen; the right, much smaller, terminates in the pylorus; the concave, or lesser edge of the stomach is turned upwards and backwards, and has attached to it the lesser omentum, the coronary vessels and nerves run along it. The great, or convex edge, is directed downwards and for- wards, and has attached to it the great omentum, the epiploic vessels and nerves run along this border ; the anterior surface of the stomach is convex, the poste- rior nearly flat. The stomach is composed of four coats, the serous, muscular, nervous or fibrous, and the mucous; the se- rous coat is derived from the peritoneum, and has been already described. The muscular layer consists of three sets of fibres ; the longitudinal are derived from the fibres of the oesophagus, and are best marked along the lesser and greater curves; the circular fibres sur- round this organ at the junction of its right third with its left extremity ; th.ey sometimes contract so as to give to the stomach an hour-glass shape ; the irregular or oblique fibres are situated chiefly around the great bulging extremity. The nervous or fibrous coat of the stomach lies be- neath the preceding ; it is composed of condensed cel- lular tissue, and strengthens the stomach considerably ; the mucous coat lines the interior of the stomach; it is of a rose pink colour, and is thrown into irregular folds, the rugae of this organ; at the pylorus this forms a distinct valve, having beneath it well-marked circu- lar muscular fibres. THE SMALL INTESTINES. 71 The stomach is supplied with blood from the coro- nary arteries, a branch of the coeliac axis, which runs along its lesser curve, the right gastro-epiploic, a branch from the hepatic, and the left gastro-epiploic, a branch of the splenic. Its nerves proceed from the pneumogastric or par vagum and the solar plexus. The SMALL INTESTINES consist of the duodenum je- junum, and ileum. The duodenum is about twelve inches in length, and extends from the pylorus to the root of the mesentry; it lies chiefly in the right hy- pochondrium, and reaches into the umbilical and left lumbar regions, it forms an irregular horse-shoe curve, in the concavity of which lies the head of the pancreas, and consists of three portions the superior transverse, the vertical and the inferior transverse the first passes upwards and to the right side as far as the neck of the gall-bladder; the second descends along the right side of the spinal column in front of the right kidney; the third portion passes transversely across the spine, in front of the second lumbar verte- bra, and behind the sup. mesenteric art. terminates in the jejunum. The duodenum has four coats, the external or se- rous is only partial, the superior portion is entirely covered by peritoneum, the middle wants this mem- brane posteriorly, and the inferior portion is unco- vered, lying between the folds oT the meso colon; its muscular fibres are chiefly circular, its fibrous coat resembles that of the stomach, its mucous coat is thrown into numerous folds at its lower third, form- ing the valvulse connivcntes. The ductus communis choledochus and the pancreatic duct open into the concave margin of the duodenum, near to and a little above the angle of junction between its descending and inferior transverse portions, generally on one of the valvulse conniventes ; its orifice is marked by a slight thickening of the membrane, The jejunum forms two-fifth of the small intestines, 72 THE LARGE INTESTINES. the ileum the remaining three-fifths ; their structure is nearly similar, consisting of an external serous coat a muscular coat, composed chiefly of circul. fibres, a fibrous coat, and a mucous lining membrane, thrown into numerous folds, the valvulae conniventes. These are most numerous in the jejunum, least so in the lower part of the ileum. The small intestines are supplied with blood, the duodenum chiefly from the gastro duodenalis art., the jejunum and ileum from the superior mesenteric art. Their nerves are derived from the solar plexus. In the interior of the small intestines are numerous glands. They are isolated in theupper part, forming the glandulae solitarae, or the glands of Brunner, but in the lower part are collected in oval groups form- ing the glandulse agminatae, or the glands of Peyer. At its lower extremity the ileum ascends from the pelvic cavity, and terminates opposite the right sacroiliac symphysis in the caecum or caput coli. The LARGE INTESTINES consist of the caecum, colon, and rectum. The c&ciim, or caput coli, is lodged in the right iliac fossa, is irregular in shape, and larger than any other part of the large intestines ; it receives the end of the ileum at its internal and posterior side, some distance above its lower extremity, and is continuous with the colon; its coats consist of a partial serous covering, deficient posteriorly, longitudinal, and a few circular muscular fibres, a fibrous coat, and a lining mucous membrane; its interior is irregular, and presents at its junction with the ileum a double valve, the ileo csecal valve; the inferior portion of this valve is the larger, and somewhat vertical, the superior is more horizontal; the structure of these valves is a fold of mucous membrane enclosing some muscular fibres. The appendix vermiformis, a small worm-like intes- tine, proceeds from the left and posterior surface of the caecum; its cavity is small, and communicates with the end of the caecum. THE RECTUM. 73 The colon extends from the caecum to the rectum, and is divided into the right ascending, the transverse, left descending, and the sigmoid flexure. The ascend- ing colon is situated in the right lumbar region, in front of the right kidney and renal vessels, the trans- verse colon passes across the spine to the left side, forming an arch, the convexity forwards, and joins the descending colon ; this is situated in the left lum- bar region in front of the left kidney and renal ves- sels, and joins inferiorly the sigmoid flexure; this is lodged in the left iliac fossa resting on the psoas, quad- ratus lumborum, and iliacus internus muscles. The structure of the colon is similar to that of the caecum, in all, the longitudinal muscular fibres are collected into three longitudinal bands ; these proceed from the appendix vermiformis, and are lost in the rectum ; one of these is anterior, the other two are on the pos- terior surface ; on their outer surface are the appen- dices epiploicse, folds of peritoneum enclosing some adi- pose tissue. The large intestines are supplied with blood from the inf. mesenteric art.; their nerves are derived from the sympathetic. The rectum descends into the pelvis from the sig- moid flexure of the colon; it proceeds from the left sacro iliac symphy sis, at first downwards and inwards towards the mesial line of the sacrum, it then bends downwards and forwards towards the perineum and beneath the bladder, and finally turning a little back- wards, it terminates in the anus ; concave in front, it receives the posterior surface of the bladder, and rests in the hollow of the sacrum ; on each side of it are the internal iliac vessels and sacral plexus. The structure of the rectum consists of a serous coat; this is only partial, the upper third is entirely covered, the middle third wants this covering on its posterior surface, and the lower third is wholly uncovered by it; a muscular coat composed of reddish longitudinal fibres, which above the anus assume a circular shape, forming the 7 74 THE LIVER. deep sphincter ani muse., a fibrous coat, well marked, and lastly a lining mucous membrane; this is thrown in- to longitudinal folds in the undisturbed state. Some have described also transverse folds, but they do not exist. The arteries of the rectum are derived from three sources, the superior hemorrhoidal from the inf. me- senteric, the middle from the internal iliac, and the inferior from the internal pudic; its nerves are derived from the sacral and sympathetic. The absorbents of the intestines are extremely numerous, those of the small intestines absorb the chyle, and are hence called lacteals; they pass through the mesenteric glands con- tained in the folds of the mesentery, and terminate in the receptaculum chyli, the commencement of the tho- racic duct; the absorbents from the large intestines pass through the lumbar glands, and terminate also in the thoracic duct. The glandular viscera of the abdomen subservient to the function of digestion are the liver, pancreas, and spleen. The LIVER is situated in the right hypochondriac and epigastric regions, of greater extent transversely than vertically; its anterior surface, concave, is .di- vided into two by the falsiform ligament, and is in contact with the diaphragm; its posterior surface, ir- regularly concave, rests on the pyloric end of the sto- mach, the duodenum, and upper extremity of the right kidney; its upper margin is obtuse and con- nected to the diaphragm by folds of the perito- neum, and the inf. vena cava; its lower margin is thin, and notched near its centre by the umbilical vein ; its lateral margins are rounded. The liver is divided into two lobes, the right and left, by the attachment of the falsiform lig. on its con- vex surface, and by the longitudinal fissure lodging the umbilical vein, and ductus venosus, on its concave surface; the left lobe is the smaller, and is not sub- STRUCTURE OF LIVER. 75 divided. From the junction of the superior and mid- dle thirds of the longitudinal fissure, the transverse fis- sure proceeds to the right side through the middle third of the liver; it lodges the two branches of the ve- na porta, the hepatic art., and hepatic duct; the hori- zontal fissure runs from the anterior to the posterior margin of the liver, and lodges the umbilical vein, and its continuation, the ductus venosus. Besides these fissures there are two depressions on the concave surface of the liver, one for the vena cava, sometimes a canal, between the lobulus Spigelii and right lobe; another for the gall bladder to the right of the horizontal and in front of the transverse fissure. The right kidney and colon sometimes mark this surface. On this surface are the three lobules of the liver viz., lobulus Spigelii, pyramidal in shape, its apex free, having the longitudinal fissure to its left, the vena ca- va to its right, and the transverse fissure in front; a tail-like process, lobulus caudatus, connects it with the rest of the right lobe; lobulus quadratus is bounded to the left by the horizontal fissure, to the right by the gall bladder, superiorly by the transverse fissure, in front by the thin margin. The liver has two coats, a serous and a fibrous ; the serous or peritonealis partial, as it does not cover the organ at the fissures, behind the gall bladder and vena cava, and within the coronary ligament; it forms the right and left lateral, coronary, and falsiform liga- ments; the first two connects the respective lobes to the diaphragm, the second surround the orifices of the vena cava hepat., the last has been already described. Ike fibrous coat is tolerably well marked, and passes into the interior of theliver with its vessels. The struc- ture of the liver consists of a number of granules, of a brownish yellow colour, united by cellular tissue. Mr. Kiernan has described the structure of the liver as composed of lobular bodies, which are found in all parts of the organ, but in the centre are of an angu- 76 THE GALL BLADDER. lar shape, while towards the circumference they ac- quire a more rounded form; running down their mid- dle is the intralobular vein, into which still more mi- nute branches pour their blood; at the base of the lo- bules these veins open into a larger one, called sublo- bular; several of these join together, and by their union form the hepatic vein, which terminates in the vena cava; around the intralobular vein ramify the vena porta, ductus hepaticus, and hepatic art., exter- nal to which is the capsular covering; in passing to and from these lobules the vessels ramify between them, and form interlobular vessels ; the portal vein in the vaginal sheath gives off numerous branches, which, previous to entering between the lobules, form the vaginal plexus. The liver is supplied with blood by the hepatic art. and vena porta, which pass transversely across the organ, each of them having a coating of cellular tis- sue derived from the capsule of Glisson, and hence collapse when cut across; the blood is returned by the venae cavae hepaticae, which unite into three or four large trunks, and terminate in the vena cava where it passes through the diaphragm ; these ves- sels have no cellular covering, remain open when cut across, and take a longitudinal course. The bile is conducted from the liver by the biliary ducts; these arise from the granules, and finally unite so as to form two ducts, one for each lobe, which again unite -and form the hepatic duct; this escapes from the transverse fissure and unites with the cystic duct to form the ductus communis choledochus, about three inches in length ; it conveys the bile into the duo- denum. The gall bladder is lodged in a sulcus on the under surface of the liver, to the right of the lobulus caudatus; pyriform in shape, its larger ext. is free, and projects beyond the thin margin of the liver, its smaller ext. terminates in the cystic duct; this, about an inch and a PANCREAS. 77 half in length, unites with the hepatic duct to form the ductus communis choledochus. The structure of the gall bladder is composed of three coats; the ext. serous is a partial coat and binds it down in situ; the second is fibrous, and the third is mucous; this is honeycomb in appearance, and is tinged with the bile. The structure of all these ducts is the same, namely fibro-mucous, as are all the excretory ducts of the body except the thoracic duct. The PANCREAS lies across the spine behind the stomach and between the two layers of the transverse meso-colon; it is composed of a larger extremity or head, which lies in the concavity of the duodenum ; a lesser ext. or tail, reaching to the spleen, and a cen- tral portion, or body ; its structure resembles that of the salivary glands. The Pancreatic duct is seen on its posterior sur- face ; it arises by numerous radicles, which unite and form the trunk; this conveys the pancreatic fluid into the duodenum. Its structure is fibro-mucous. The pancreas is supplied with blood from the splenic and the pancreatico duodenalis art. The SPLEEN is situated in the left hypochondrium, behind the great bulging ext. of the stomach, and above the left kidney. It is a soft spongy mass, of a crescentic shape ; the concavity, turned inwards, re- ceives the vessels and nerves. The convexity is in contact with the abdominal parietes beneath, and the diaphragm above. The coats of the spleen are a se- rous and fibrous, the former nearly perfect, the latter weak and thin; its internal structure is composed of shreds of cellular tissue filled with blood. The spleen is supplied with blood from the splenic art.; its nerves are derived from the sympathetic. The principal vessels of the abdomen are the aorta and its branches, the vena cava inferior, and the vena porta. (See Vascular System.) The principal nerves are the symphathetic and the lumbar plexus, lying 78 HERNIA. imbeded in the psoas mag. muse. (See Nervous System.) SECTION IV. HERNIA. The anatomy of hernia is intimately connected with that of the abdominal parietes, and may well be considered here. Inguinal hernia^ so called from its appearance in the inguinal region or groin; of it we have two varie- ties, one named oblique inguinal hernia, from the ob- lique direction which the tumour takes between the abdominal muscles, following the course of the sper- matic cord, whence it is also occasionally called sper- matocele the other is called direct inguinal hernia, from its protruding directly forwards through the external abdominal ring. Femoral hernia appears in the upper inner and an- terior part of the thigh, where it descends beneath Poupart's ligament on the inner side of the femoral vessels. Umbilical hernia protrudes through the umbilicus, taking the course of the umbilical cord. The term Ventral hernia indicates the protrusion of one or more of the viscera through some other re- gion of the abdomen than those specifically mention- ed; the situations where this species of hernia most frequently occurs, are at the linea alba, the linese semilunares and transversse. The other forms of th e disease are of minor importance. Oblique Inguinal Hernia. In this form of the disease, the hernia takes the course of the spermatic canal with the spermatic cord ; that is, it escapes from the abdomen at the in- ternal abdominal ring, about midway between the spine of the ilium and the symphysis pubis, descends obliquely forwards and inwards, escapes throughout SUPERFICIAL FASCIA. 79 the external abdominal ring, and finally descends into the scrotum. On raising the skin a dense layer of cellular sub- stance is brought into view this is the superficial fascia of inguinal hernia. This is perfectly continuous with the common subcutaneous cellular tissue beneath the integuments in other regions of the body, and dif- fers but little from it, except in being a little denser in structure, and of more importance from its con- nexion with hernia. Above, the superficial fascia is continuous with the cellular tissue covering the lower surface of the thorax, and upper part of the abdomi- nal muscles; inferiorly it descends over Poupart's ligament into the thigh, and there becomes continu- ous with the superficial fascia of the femoral region ; nearer the pubes it passes over the spermatic cord in the male, and descends into the scrotum and perineum, where it identifies itself with the loose cellular tissue of these regions. On the mesial line, the superficial fascia descends from the linea alba, on the dorsum of the penis, and here forms a tolerably dense structure, the false suspensory ligament of the penis, which connects this organ to the abdominal parietes. In the female it is loaded with a quantity of adipose tissue and descends into thelabium. The cutaneous surface of the superficial fascia is rough and cellular, and is intimately connected to the integuments; its deep surface is more compact and smooth, and is ap- plied against Scarpa's fascia, which thus separates it from the abdominal muscles. The use of this fascia is to allow of the free motions of the integuments on the abdominal muscles, and to assist these in the support of the abdominal viscera. Some anatomists have divided the superficial fascia into several layers; this is quite an arbitary division, and without any practical advantage, as the number of layers varies in almost every subject, and depends much on the dexterity of the operator; its thickness also varies much in different individuals,in some being 80 SCARPA'S FASCIA. but a few in others many lines in depth. In it we meet with several superficial arteries, veins, nerves, and lymphatic glands. The arteries are the external epi- gastric, and branches from the external circumflexa ilii, and pubic arteries. They arise from the femoral artery a little below Poupart's ligament, ascend in front of the ligament, and are lost in the superficial fascia and integuments. The external epigastric is the largest, it ascends obliquely inwards, towards the umbilicus, where it terminates. The nerves are small, and are derived from branches of the lumbar plexus. The lymphatic glands are four or five in number ; they take a nearly transverse course, parallel to Poupart's ligament, some lying a little above, others somewhat beneath the ligament. They are named the superior inguinal glands, to distinguish them from another set of inguinal glands, met with below Poupart's liga- ment more numerous, and arranged in the vertical direction; they are contained in a sheath or capsule formed in the superficial fascia. The superior set communicates with the absorbents of the genital or- gans. The inferior inguinal glands, on the contrary, communicate with the absorbents of the lower extre- mity. On raising superficial fascia a distinct layer of cel- lular tissue "Scarpa's fascia," is exposed. This is firmly attached to, and appears to arise from the fas- cia lata, abouthalf an inchbelowPoupart'sligament, whence it ascends over the ligament, to be gradually lost on the outer surface of the external oblique mus- cle : it is sometimes described as the deep layer of the superficial fascia, with which it is so intimately connected, as to give to this the appearance of being firmly attached to Poupart's ligament; they are, in- deed, with difficulty separated. On Scarpa's fascia femoral hernia rests when it turns up over Poupart's ligament. These fasciae, excepting the skin, form the most superficial co- verings of an inguinal hernia. PILLARS OF RING. 81 On raising Scarpa's fascia the outer surface of the external oblique muscle is brought into view: this is here perfectly tendinous, in order that itmay the more effectually support the abdominal viscera ; it forms, with the fellow of the opposite side, a broad sheet of tendon, extending directly across the lower part of the abdomen. Each tendon is somewhat triangular in shape: one margin is turned inwards, and unites with its fellow on the mesial line, to form the linea alba ; a second is directed upwards and outwards, slightly concave, and gives attachment to the fleshy fibres of the muscle ; the third margin is turned downwards and outwards and here presents a thickened con- densed cord, named Poupart's ligament. The tendinous fibres of the external oblique muscle are distinct and well marked : by far the greater num- ber take a direction downwards and inwards ; a few may be observed to decussate with these taking an oblique course upwards and inwards. As we trace them towards the pubes, they increase in strength and density, and having arrived within about an inch and a half of this bone, they separate into two bands, and thus leave an interval between them, named the ex- ternal abdominal ring. The bands are named the pillars of the ring. One of them, the internal, lies anterior and superior to the other; it is a broad flat sheet of tendon, which, passing inwards, descends in front of the symphysis pubis, into which it is implan- ted, decussating with its fellow of the opposite side. A few fibres pass from it to be continuous with the fascia lata of the opposite side ; others may be traced descending on the dorsum of the penis, contributing to form the true suspensory ligament of this organ. The external pillar of the ring, is stronger and shorter than the other, is a continuation of Poupart's liga- ment : it is a round fibrous cord ; it descends inwards, and is inserted into the spine or tubercle of the pubes ; on it the spermatic cord rests as it escapes through the ring. Here the external pillar is excavated on 82 PILLARS OF RING. its superior surface (as will be seen in a future stage of the dissection) to accommodate the cord, and thus preserve it from injury. Inferiorly, or towards the thigh, the descending fibres of the external oblique muscle become condensed and form Poupart's ligament, a dense fibrous cord, which descends inwards from the anterior superior spinous process of the ilium to the pubes, into which itis implanted by two attachments ; one, already de- scribed as the external pillar of the ring, is inserted into the spine or tubercle of the pubes; the other is an expansion from this, and forms a broad thin liga- ment, which ascends obliquely inwards, to be inserted into the internal extremity ofthelineainnominata; it is named Gimbernaut 's ligament, or third insertion of the crural arch. It lies superior and posterior to the external pillar of the ring, or second insertion of Poupart's ligament. Itis more immediately connect- ed with femoral hernia, with which we shall here- after describe it more minutely. Near the ilium Poupart's ligament is thin and weak, but it increases much in density as it aproaches the pubes. Its inferior margin slightly concave, and directed somewhat forwards, gives attachment to the iliac portion of the fascia lata. To its superior edge are connected the external and internal oblique, and transversalis muscles, and the transversalis and iliac fasciae. A few tendinous fibres of the external oblique muscle decussate with those just described; they are the inter columnal bands. They arise from near Pou- part's ligaments, ascend inwards, forming curves con- vex towards the pubes,. and are gradually lost in the tendon as they approach the linea alba; towards the ilium they are indistinct, but near the pubes they be- come strong and well marked ; in general one strong- er than the rest rounds off the apex of the external abdominal ring, and thus assists in restraining the increase of this opening. The use of the intercolumnal EXTERNAL ABDOMINAL RING. 83 bands is to prevent the separation of the descending fibres of the external oblique, between which, inter- vals occasionally exist, exposing the fibres of the internal oblique muscle. Hitherto the external abdominal ring has not been sufficiently apparent ; it is concealed from view by a layer of cellular tissue, the external spout-like or Cam- per's fascia, or intercolumnal fascia, which descends from the edges or margins of the ring, on the spermatic cord, upon which it is insensibly lost. Some describe this fascia as being derived from the intercolumnal bands. Scarpa considers it to be a prolongation of the fascia which has received his name. It is so intimately connected with all these structures, that it is impossible to assign it to any distinct origin. It forms the third covering of an inguinal hernia, whether oblique or direct. On dissecting off this fascia, the external abdominal ring is exposed. This may be now seen to be, as al- ready described, an opening in the external oblique tendon, formed by the divergence of its descending fibres; it transmits the spermatic cord in the male, the ligamentum teres in the female. It is triangular in shape ; the, apex, directed upwards and outwards, and rounded off by the intercolumnal bands ; its base inferiorly is formed by the crest of the pubes; its in- ternal margin, the longest, is formed by the internal pillar of the ring, its external margin by the external pillar; its greatest length corresponds to that of its internal margin, and varies from one inch to one inch and a half; it is the outer or anterior opening of the in- guinal or spermatic canal ; through it an inguinal hernia emerges, to descend into the scrotum. If the spermatic cord be now cut across, a little beneath the ring, and gently raised, it will be seen that it has escaped through this aperture, resting not on the bone, but on the external pillar of the ring, and th,at, behind the external abdominal ring, some fibrous structures exist which assist in preventing the 84 THE TRIANGULAR LIGAMENT. protrusion of hernia through this opening, directly from behind, or, in other words, prevent the forma- tion of a direct inguinal hernia; these are Colles's fascia, and the conjoined tendons. Colles's fascia, or the triangular ligament of inguinal hernia, is liable to much variety, being in some sub- jects well marked, in others altogether wanting ; it lies behind the external abdominal ring, in front of the conjoined tendons, and partially concealed by the internal pillar of the ring. It is formed by a few fibres, which are derived from the posterior surface of the external oblique tendon of the opposite side ; the ligaments of either side, therefore, decussate. Its base is implanted into the crest of the pubes ; one margin is towards the linea alba, the other is free, and looks upwards and outwards. The conjoined tendons lie behind, and to the outside of the preceding: they are the united tendons of the internal oblique and transversalis muscles, which here pass in front of the rectus muscle ; to be inserted into the upper part of the symphysis and crest of the pubes; the external margin of the conjoined tendons is pro- longed beyond the outer edge of the rectus muscle ; it here is inferiorly implanted into the linea innominata, where it is continuous with Giinbernaut's ligament. Above this the transversalis fascia is implanted into it; here, indeed, the two structures frequently ap- pear to be contiouous one with the other. From the great strength and transverse extent of the conjoined tendons, ancl their position immediately be- hind the external abdominal ring, they contribute much to the security of the abdomen in this situation, and thus prevent the formation of direct inguinal her- nia. The inguinal or spermatic canal is an oblique canal or passage between the abdominal muscles, which transmits the spermatic cord in the male, the liga- mentum teres in the female. It commences at the internal abdominal ring^ as yet concealed from view INGUINAL CANAL. 85 by the lower margin of the internal oblique muscle. This is an opening in the transversalis fascia, situated about midway between the spine of the ilium and the symphysis pubis, but somewhat nearer the former, about three-quarters of an inch above Poupart's liga- ment; from this the canal descends forwards and in- wards between the oblique muscles, and terminates at the external abdominal ring. Its length is about one inch and a half, if we measure the distance between the two nearest points of the two rings ; three inches, if we measure between the two furthest points of these openings, and two and a half inches, if we measure between the intermediate points. The inguinal canal is bounded, above, by the lower margins of the internal oblique and transversalis mus- cles, below by Poupart's ligament, in front by the ex- ternal oblique tendon and the lower margin of the in- ternal oblique, behind by the transversalis fascia, the conjoined tendons, Colles' ligament, and occasionally a few fibres of the internal oblique. The superior boundary of the inguinal canal is formed by the lower margins of the internal oblique and transversalis muscles; these muscles are here in- timately connected, particularly as we approach the pubes towards the ilium theyare partially separated. Beneath the former, the spermatic cord may be seen to emerge, as it descends; a few muscular fibres pass off along with it, which form the cremaster muscle. In some subjects a diiferent arrangement exists; which is, that the spermatic cord passes out between the fibres of the internal oblique, some of which thus lying beneath the cord, this structure then escapes through a perfectly muscular opening. In this stage of the dissection, the extent of origin of the internal oblique muscle from Poupart's ligament maybe ob- served ; it in general arises from the external two- thirds and upper surface of the ligament, but is liable to much variety in this respect ; the fibres descend inwards to terminate in the conjoined tendons. 8 86 INTERNAL ABDOMINAL RING. The cremaster muscle arises not only from the lower margin of the internal oblique, but takes a few fibres from the transversalis muscle, from the neighbouring surface of Poupart's ligament, and from the pubes a little external to its tubercle; from these diiferent ori- gins, its fibres descend around the spermatic cord, but chiefly on its outer and anterior surface, forming a series of loops, the concavities of which are directed upwards, and are finally implanted into the outer sur- face of the tunica vaginalis, and into the scrotum, to the lower part of which they descend. Between the fibres of the muscle, the spermaticus supeficialis nerve, a branch from the ilio-scrotal descends, to be lost in the coverings of the testis. Poupart's ligament bounds the inguinal canal infe- riorly. Near the internal ring, the cord is about three-quarters of an inch above Poupart's ligament, but, as it descends, it gradually approaches the liga- ment, until at length it lies imbedded in its upper surface which is grooved for its protection. The anterior boundaries of the inguinal canal have been already sufficiently described. It & posterior walls are the fascia transversalis and the conjoined tendons this latter structure forms but a small portion of tjie posterior boundary of the canal it lies behind the external abdominal ring. The transversalis fascia will be better seen immediately. The internal abdominal ring is formed by the passage of the spermatic cord through the transversalis fascia; as the cord passes through the fascia it draws with it, as it were, a cellular prolongation from the fascia; this descends, and is gradually lost upon the cord; it is named thefasciapropria, or internal spout-like fascia. It forms the fifth, or the immediate covering of the hernial sac, hence its name of fascia propria. It is well exposed by gently drawing downwards the spermatic cord. The internal abdominal ring is a little nearer the ilium than the symphy sis pubis, its inner margin being MEASUREMENT OF PARTS. 87 precisely midway between these two points. It lies nearly opposite the external iliac artery, and about one-half to three-quarters of an inch above Poupart's ligament. Directly above it the lower fibres of the transversalis muscle cross from their origin, from the external third or half of Poupart's ligament, almost transversely inwards, to become identified with the internal oblique muscle, and implanted with it into the conjoined tendons. Occasionally, as Mr. Guthrie has described, a few fibres of the transversalis muscle pass behind the cord. Along the internal and inferior part of the internal ring, and contained in the trans- versalis fascia, ascends the epigastric artery. This artery arises from the external iliac, a little above Poupart's ligament; it at first descends, then curves upwards, winding around the cul de sac of the peritoneum, and then ascends inwards, enters the sheath of the rectus muscle, and terminates by anas- tomosing with the internal mammary artery. It lies about a quarter of an inch distant from the cord. The epigastric artery is accompanied by one or two veins ; if by one, the vein lies to its inner or pubal side; if by two, the artery lies between the veins. The following measurements of the parts con- nected with hernia are given by Sir A. Cooper. M. r. ' anterior superior spinous process of the ins. ins. ilium ..... '5J 6 tuberosity of the pubes . . . l| 1 f inner margin of the lower opening of the abdominal canal . . . OJ 1 inner edge of the internal abdominal ring 3 3J to the middle of the iliac artery . . 3_J 3| iliac vein . . . . . . 2f 2J origin of the epigastric artery . . 3 3J course of the epigastric artery on the inner side of the internal abdomi- nal ring . . . . . 2f 2-J w middle of lunated edge of the fascia lata 3| 2 J 88 ' TRANSVERSALIS FASCIA. M. F. From the anterior edge of the crural arch to ins. ins. the saphena vein . . 1 1J symphysis pubis to the middle of the crural ring . . 2J 2| The transversalis fascia ;is a layer of condensed cel- lular tissue or fascia, situated between the transver- salis muscle and the peritoneum, and particularly well marked, inferiority, where the internal oblique an d transversalis muscles are deficient. Superiorly, the transversalis fascia is gradually lost in the loose cellular tissue which connects the perito- neum on its anterior and posterior surfaces to the ab- dominal parietes, but inferiorly becomes strong and well marked. Here, on the outer side, it is attached to the inner edge of the crest of the ilium, more in- ternally to Poupart's ligament, behind which it unites with the fascia iliac to prevent the protrusion of hernia beneath this ligament ; still more internally, or oppo- site the fermoral vessels, it descends into the thigh, forming the anterior layer of the canal in which these vessels are lodged; still nearer the pubis, it is attached to the conjoined tendons, and the outer edge of the rectus muscle, a layer of it passing also behind this muscle to be continuous with that of the opposite side. At the point where the spermatic cord perforates the transversalis fascia, namely, the internal abdomi- nal ring, the fascia frequently presents a well-defined semilunar border, which bounds the ring to its inner Bide ; in other cases it terminates gradually in this di- rection ; in all instances a prolongation is derived from it which descends on the spermatic cord, and forms the fascia propria, or fascia spermatica, of Sir A. Cooper. Some anatomists describe the transver- salis fascia as being composed of two layers, between which the epigastric artery ascends,|one of these being attached to the edge of the rectus muscle, the other passing behind the muscle to the opposite side. The transversalis fascia is of use in strengthening the ab- HERNIA IN FEMALE. 89 dominal parietes inferiorly, where a deficiency exists in the internal oblique and transversalis muscles. From its connexion with the transversalis and rectus muscles, it is made tense by the action of these, and is thus rendered still more capable of opposing the protrusion of a hernia. As the hernia is first protruded against the inter- nal abdominal ring, it pushes before it the peritoneum, which forms the hernial sac, emerging through the ring it descends in front of the spermatic cord, and here receives a covering from the fascia propria; de- scending still further, it escapes beneath the lower margin, or between the fibres of the internal oblique muscle, here it enters the sheath of the cremaster muscle, and continues its course to the external abdo- minal ring ; it now,turning forwards, passes through this opening, where it becomes invested by the exter- nal spout-like fascia; it now descends into the scrotum, covered still further by Scarpa's fascia, the superficial fascia, and the integuments. It thus is covered by the integument, the superficial fascia, Scarpa's fascia, the external spout-like fascia, the sheath of the cremaster muscle, the fascia propria, and the peritoneum, forming the hernial sac. As a hernia descends into the scrotum, beneath the coverings of the spermatic cord, it finally arrives im- mediately above the testis, in which position it is re- tained by the attachment of the spermatic coverings to the upper and back part of this organ, where its vessels and nerves enter. Now the principal points to be attended to, in the anatomy of oblique inguinal hernia, are 1st, its coverings; 2d, the part of the canal where stricture most frequently occurs; 3d, its relation to the epi- gastric artery, to the spermatic cord, and the testis. Oblique inguinal hernia in the female occurs much less frequently than in the male, owing to the smaller size of the inguinal canal. It descends into the labium 8* 90 DIRECT INGUINAL HERNIA. and is in general small. It is almost always reducible. Should it become strangulated, the operation will not differ essentially from that recommended for the male. The lower part of the peritoneal bag, accord- ing to Sir A. Cooper, contains only water. The in- cisions should not be prolonged much into the labium. Direct inguinal hernia. From the deficiency in the external oblique tendon, described in oblique inguinal hernia under the name of the external abdominal ring, it follows that a hernia may be protruded di- rectly forwards from the abdomen through this aper- ture, without transversing the inguinal canal ; this will therefore form the direct inguinal hernia. Fortunately nature has so protected this opening posteriorly, that this species is comparatively rare. The parts that oppose its formation lie behind the ring ; they are, the triangular ligament, or Colles' fascia, the conjoined tendons, the edge of the rectus muscle, and the transversalis fascia, attached to the outer edge of this muscle and to the conjoined ten- dons. These barriers are not, however, in all cases suffi- cient. As a direct inguinal hernia makes its way forwards through the external ring into the scrotum, it pushes before it the peritoneum which forms the hernia! sac; it next either bursts through, or carries with it, the transversalis fascia, and then passing to the outer edge of the rectus muscle and the conjoined tendons, it escapes through the external ring, and is here covered by the external spout-like fascia, the superficial fascia, and the integument. It is evident that the hernia can receive no covering (or at least a very partial one) from the cremaster muscle, nor from the fascia propria of oblique inguinal hernia, as it does not descend through the inguinal canal.* The *Sir A. Cooper states that it receives a covering from the trana- versalis tendon and fascia. By the former we consider him to mean an expansion from the transversalis fascia, where it is at- tached to the conjoined tendons. INGUINAL POUCHES. 91 epigastric artery lies to its outer side. As the hernia emerges from the external ring, it lies internal, and a little posterior, to the spermatic cord. Direct thus differs essentially from oblique inguinal hernia in its coverings, and in its relations to the epi- gastric artery and spermatic cord. If we examine the lower part of the parietes of the abdomen on their inner surface, by raising the in- testines from the cavity of the pelvis, leaving the peritoneum in situ, we shall there see two depressions, or fossse, on each side, which seems to invite, as it were, to the protrusion of a hernial tumour. Between these three projecting cords maybe noticed; one of these is situated on the mesial line, and is formed by the urachus, which ascends from the superior fundus of the bladder to the umbilicus; the remaining two are situated one on each side. They are formed by the degenerated umbilical arteries, which ascend from the lateral surfaces of the bladder, converging to the umbilicus. These depressions are named the internal and ex- ternal inguinal fossse or pouches. The internal inguinal fossa lies between the urachus and the degenerated umbilical artery, the first of which separates it from its fellow of the opposite side. It is triangular in shape, the base inferiorly being formed by the crest of the pubes. It lies opposite to the external ring, and thus leads to the formation of direct inguinal hernia. The external inguinal fossa lies to the outer side of the umbilical artery ; it lies superior and external to the other, and is somewhat larger; it leads to the internal ring, and consequently to the formation of an oblique inguinal hernia. The projecting cords, formed by the urachus and umbilical arteries, contribute more to the formation of hernia than the inguinal fossae ; as they, when the intestines are propelled against them by the action of the abdominal muscles, give to the propelling force, 92 FEMORAL HERNIA. and consequently to the viscera, a direction forwards towards the fossae. Femoral hernia. This form of hernia is more fre- quent in the female than in the male, in consequence of the greater breadth of the pelvis in the former. It is sometimes named crural hernia, being called from its making its appearance, when first noticed, in the thigh ; in the upper, inner, and anterior part of which region it descends beneath Poupart's ligament, to the inner side of the femoral vessels. Beneath the skin is the superficial fascia. This is fehe common subcutaneous cellular tissue met with in every part of the body beneath the integuments ; it is Here well marked, and is frequently loaded with fat. On all sides it is continuous with the surround- ing cellular tissue. Externally a few transverse fibres may be occasionally met with in it. No anatomist, so far as we are aware of, has as yet exercised his ingenuity in the vain-glorious task of dividing it into any definite number of layers. It forms the most superficial covering of the femoral hernia. In the superficial fascia we notice several arteries, veins, nerves, and lymphatic glands. The arteries are branches of the external circumflexa ilii, external p^u- dic, and superficial epigastric arteries; they arise from the femoral artery a little below Poupart's lig- ament, perforate the cribriform fascia, and are lost in the superficial fascia and integuments. The ex- ternal circumflexa ilii branches pass outwards be- hind the ilium; the external pudic to the organs of generation; whilst the superficial epigastric ascends inwards over Poupart's ligament, to be lost in the parietes of the abdomen. The external pudic and superficial epigastric are frequently wounded in the operation for strangulated femoral hernia, and may require the ligature. The veins are branches from the surrounding inte- guments, and the great or internal saphena vein. This large vein commences at the inner side of the foot and FASCIA LATA. 93 leg, ascends along the internal surface of the thigh, curves outwards at its upper part, and at about an inch and a half distance from Poupart's ligament, perforates the cribriform fascia, through the sa- phenic opening, to join the femoral vein. In some cases a second large vein ascends along the anterior surface of the thigh, which either terminates in the saphena or in the femoral vein. In operating for strangulated femoral hernia, as well as in other ope- rations in this region, the saphena vein is much ex- posed. It may be avoided by not prolonging our in- cisions too much inwards. Not unfrequently it becomes varicose, and may be mistaken for a femoral hernia. The nerves met with in the superficial fascia are small branches derived principally from the anterior crural. The lymphatic glands compose the interior set of in- guinal glands. They are arranged in the vertical di- rection, and consist of two sets, the superficial and deep. The superficial are three or four in number, and are enclosed in a capsule of the superficial fascia. The deep are two or three in number, they accompany the femoral vessels ; one is almost constantly lodged in the femoral ring. On raising the superficial fascia, the fascia lata is brought into view. This is a dense layer of fibrous structure which invests the muscles of the thigh. Inferiorly it is attached to the tendons and ligaments about the knee-joint; from this it ascends, fbrming sheaths for the different muscles, and sending in pro- cesses between them. Having arrived at the upper and anterior part of the thigh ( where it is connected with the anatomy of femoral hernia,) it divides into three portions, the iliac, pectineal, and cribriform fa seise. The iliac (so called from its connexionwith the os ilii, ) or external portion of the fascia lata, is the strongest; posteriorly it is attached to the crest of the ilium ; in front we find it closely attached to the lower margin of Poupart's ligament. As we trace it inwards towards the pubes, it terminates in an elongated process, which 94 PECTINEAL FASCIA. passes in front of the femoral vessels, gets to their inner side, and is implanted into the front of the pec- tineal portion of the fascia lata. Some of its fibres are here reflected behind Poupart'sligament, they become 'continuous with the base of Gimbernaut's ligament, and are inserted with it into the ilio-pectineal line. The superior edge of this prolonged portion of the fascia lata is attached to Poupart's ligament its infe- rior margin is free and concave, the concavity looking downwards and inwards ; this portion of it is named Key's ligament, or the falciform process of the fascia lata, whilst its point of attachment to the pubic por- tion of the fascia lata is called Colles' ligament. A short distance below Key's ligament the iliac portion of the fascia lata is gradually prolonged into the cribriform fascia, but not unfrequently presents, in the dissected state, a well-defined edge at the outer side of the femoral artery. Still more inferiority, the iliac portion of the fascialatabecomes continuous wjth the pectineal portion in front of the femoral vessels ; they here conjoined form a well-defined semilunar margin, the concavity of which is turned up wards, and forms Burns' ligament. This margin of th e fascia lata, on a careful examination, will be found to be reflected backwards on the anterior surface of the femoral ves- sels, and so intimately united with the sheath, as to prevent altogether the descent of a hernia beneath it. The pectineal or pubic or internal portion of the fascia lata lies in front of the pectineus muscle internally it is attached to the symphysis pubis, where it lines the gracilis and adductor muscles; as we trace it outwards it passes in front of the pectineus muscle, gets behind the femoral vessels, at the outer edge of which it meets with the tendons of the psoasmagnus andiliacus inter- ims muscles: it here divides into two laminae, one of which passes forwards, to be attached to the posterior surface of the external or iliac portion of the fascia lata, whilst the other passes backwards to be attached to the capsular ligament of the hip-joint. CRIBRIFORM FASCIA 95 Superiorly the pectineal fascia ascends in front of the pectineus muscle, to be inserted in the ilio-pectineal line, where it becomes continuous with the fascia ili- aca, and with Gimbernaut's ligament. Inferiorly it becomes continuous with the iliac portion of the fascia lata, to form Burn's ligament. Femoral hernia, as it descends, rests on the pecti- neal fascia. Between these two portions of the fascia lata, and immediately in front of the femoral vessels, an oval-shaped space exists, which is covered over by a thin layer of cellular substance, named the cribriform fascia, or middle portion of the fascia lata. This is in general described as a process of the fascia lata, with which indeed it is perfectly continuous at the circum- ference of the opening; at the same time, it is so inti- mately connected to the superficial fascia, being in fact identified with it, that it may be, with equal propriety, described as being derived from this fascia. The cribriform fascia is perforated, as its name im- plies, by a number of foramina, which transmit nu- merous veins and nerves, passing between the super- ficial and deeper parts. One larger than the rest is formed by the saphena vein dipping in to join the fe- moral ; this is the saphenic opening ; through it a fe- moral hernia most frequently passes forward beneath the superficial fascia ; it is bounded inferiorly by Burn's ligament. From the little resistance the cri- briform fascia affords, a femoral hernia soon makes its way through it; this it effects either by bursting through the fascia, or dilating one of the openings in it, most frequently the saphenic opening. Having examined the parts on the anterior surface of the thigh, we proceed to ascertain by what means a hernia is enabled to escape from the cavity of the ab- domen, so as to descend behind the fascia lata. For this purpose draw the peritoneum and viscera out of the iliac fossa, and examine the parts which descend beneath Poupart's ligament. As this ligament stretches $6 FASCIA ILIACA. across the brim of the pelvis, (between the anterior superior spinous process of the ilium and the tubercle of the pubes) it leaves a large space (the crural arch) between it and the bone, by means of which several structures are transmitted from the pelvis to the thigh, or in the opposite direction. Thus between the spine of the ilium, the inguino-cutaneous nerve descends, internal to this the psoas magnus and iliacus internus muscles, and between them the anterior crural nerve, descend in a deep fossa ; still more internally the fe- moral vessels pass. On the inner side of these the absorbent vessels from the lower extremity ascend through a well-marked opening (the femoral ring.) So many parts thus passing beneath Poupart's liga- ment, nearly obliterate the space between it and the bone, so that the descent of a femoral hernia is, by these means, at least partially prevented. As, how- ever, many interstices must exist between these parts, it becomes necessary that some additional structure should exist, in order to preserve the integrity of the abdominal cavity. This structure does exist, and is formed by the junction of the transversalis fascia and the fascia iliaca behind Poupart's ligament. The fascia transversalis descends from the inguinal canal, passes backwards, and behind Poupart's liga- ment meets with the fascia iliaca. This is a dense layer of fascia, which invest the an- terior surface of the iliacus internus muscle; externally and superiorly it is firmly attached to the inner lip of the crest of the ilium. Tracing it inwards, it lines the muscle, passes behind the external iliac vessels, send- ing off at the same time an expansion, which passes in front of these vessels, binds them down, and forms the fascia propria of the external iliac artery, first de- scribed by Mr. Abernethy. At the inner side of the iliac vessels, the fascia iliaca becomes attached to the ilio-pectineal line, whence it descends into the pelvis, under the name of the pelvic fascia. Near the pubes FEMORAL RING. 97 the fascia iliacabecomes continuous with the pectineal portion of the fascia lata, and Gimbernaut's ligament. Inferiorly, or towards the femoral region, the fascia iliaca curves forwards, and meets the transversalis fascia immediately behind Poupart's ligament, where the two fasciae, united, form a dense whitish tendinous line, which indicating the course of the internal cir- cumflexa ilii vessels, extends from the spine of the ilium to the outer edge of the femoral artery, and thus precludes the possibility of a hernial tumour descend- ing between these points. At the outer side of the femoral artery the fascia transversalis and the fascia iliaca separate ; the fascia transversalis descends into the thigh in front of the femoral vessels, whilst the fascia iliaca descends behind them, thus enclosing these vessels in a distinct well- marked sheath. This, the sheath of the femoral ves- sels, is of a funnel shape; the base superiorly, the apex inferiorly, is gradually lost in the cellular cover- ings of the femoral vessels in the thigh. The femoral artery and vein are not in close contact whilst contained in the sheath, but are separated by a septum or partition, which passes from its anterior to its posterior wall ; and which, thus opposing the sepa- ration of these walls, prevents the descent of a hernia between the femoral vessels and the fascia transver- salis, or anterior wall of the femoral sheath. In ad- dition to this, the fascia transversalis is connected by cellular tissue to the cellular covering of the vessels, so as to assist materially in preventing a descent of a hernia in this direction. On the inner side of the femoral vessels, we have just stated that a large aperture exists for the trans- mission of the absorbent vessels from the lower extre- mity. Here the provisions against the descent of a hernial tumour are but trifling, and here therefore it is that a femoral hernia first makes its way from the cavity of the abdomen. This opening is named the 9 98 COURSE OF FEMORAL HERNIA. femoral ring, and should be attentively studied. It is as yet concealed from view by a delicate layer of cellular tissue, which may be described as thelermi- nation of the fascia transversalis, on the inner side of the femoral vessels. This forms the fascia propria or femoral hernia, inasmuch as a hernial sac, protruding through the femoral ring, carries the fascia before it, and thus receives from it an immediate investment in a fascia propria. Although in the natural state the fascia propria is thin and delicate, yet in old cases of hernia it becomes thickened and condensed, so as to present a membranous appearance. In some cases it may be burst through, so that no fascia propria will then exist. Mr. Guthrie has recorded an instance of this. On removing the fascia propria, the femoral ring will be at once exposed. It is triangular in shape, the base externally at the femoral vein, the apex internally at Gimbernaut's ligament; it is bounded in front by Poupart's ligament, and the reflected portion of the falciform process of the fascia lata. behindby the hori- zontal ramus of the pubes, covered by the pectineus muscle and the pectineal fascia. The spermatic cord, or ligamentum teres, lies a little above and in front of it, and the epigastric artery curves to its outer side. In it we often meet with a lymphatic gland. Here, then, is the unprotected part of the abdomen, through which a femoral hernia descends into the thigh. As the hernia escapes through the ring, it pushes before it the peritoneum, which forms the hernial sac, as also the fascia propria, which, together with the lymphatic gland in the ring, affords but a feeble resistance ; the latter is soon pushed aside, the former becomes one of the coverings of the hernia, which, descending into the thigh beneath Poupart's ligament, rests on the pectineal fascia, behind the fal- ciform process of the fascia lata. It soon arrives op- posite the cribriform fascia. Its further descent is OBTURATOR HERNIA. 99 prevented by the convexity of the saphena vein, by the attachment of Burn's ligament to the front of the femoral vessels, and by the motions of the thigh on the pelvis. Meeting with little resistance from the cribriform fascia, it changes its course, turns for- wards, bursting through the fascia, or dilating one of the apertures in it, most frequently the saphenic open- ing, and lies beneath the superficial fascia". . It soon changes its course a second time ; it now turns up- wards, ascends over Poupart's ligament, and finally rests above this ligament, on Scarpia's fascia of in- guinal hernia, which alone separates it from the ten- don of the external oblique muscle. It is here then covered by the integument, superficial fascia, fascia pro- pria y and hernial sac. We have stated that the femoral ring is bounded internally by Gimbernaut's ligament. This is the third insertion of Poupart's ligament, from the pubic ex- tremity of which it extends obliquely inwards and backwards, to be inserted in the ilio-pectineal line ; it is triangular in shape, the apex turned inwards to- wards the pubes ; it base is directed outwards, is se- milunar, and forms the inner boundary of the femo- ral ring ; one edge is turned forwards, and is attached to Poupart's ligament; the other is directed back- wards and inwards, and is implanted into the ilio- pectineal line. Gimbernaut's ligament is of use in preventing the descent of a femoral hernia on the inner side of the femoral ring. The femoral ring possesses in many subjects a re- lation which should not be overlooked; it is the obturator artery. This vessel in general arises from the internal iliac artery. Where this is the case, it can have no relation to a femoral hernia ; but in numerous instances it will be found to arise from the epigastric, close to the origin of this vessel from the external iliac artery. Now as its ultimate distribution is to the parts in 100 THE KIDNEYS. the neighborhood of the obturator foramen,- it ne- cessarily follows, when such is its origin, that in order to arrive at this foramen, it must cross the femoral ring, and consequently a femoral hernia, if such should exist. As it proceeds to the foramen, it may either pass directly to it along the outer side of the neck of the hernia ; or it may first pass along its posterior surface, and then enter the foramen: or it may wind along the anterior surface of the neck of the sac, and then descend to the inner side. SECTION V. The Urinary Organs. These organs consist of the kidneys, ureters, blad- der, and urethra. The KIDNEYS are situated one on each side, in the right and left lumbar regions, behind the colon, in front of the quadratus lumborum muse., and corre- spond to the last two dorsal and first two lumbar ver- tebrae, reaching from the last rib to the crest of the ilium; the anterior surface is convex, the posterior flattened ; their extremities are convex, the upper being a little the larger, the ext. margin is convex, the int. concave and notched for the passage of the vessels and ureters ; the right touches the liver superiorly, the caecum inferiorly ; the left the spleen above, the sigmoid flexure of the colon below; each kidney is surmounted by the suprarenal capsule. The kidney has but one coat, the fibrous; it is strong and well marked. The internal structure of the kidney is composed of the secretory or cortical substance, and the excretory or tubular portion. The secretory or cortical substance forms its greater portion and occupies its outer part; it is arranged in conical masses, the cones, about fif- teen in number, which terminate in pointed extremi- SUPRARENAL CAPSULES. 101 ties, the mammillary processes ; these are about twelve or thirteen in number, and are surrounded by the calyces. The tubuli uriniferi proceed from the cortical sub- stance, to which they give a striated appearance; they open on the mammillary processes. The calyces, s>x or-e^gVi; in number, ftyrm conical cups, into which '%e ur^ne i dropped from the mam- millary processes ;. they unite into three tubes, the in- fundibula, wkich Uiutingforor;' a 'f am oil-shaped tube, the pelvis of tne kidrfey : this te?ihmht3S in iue ureter. Each kidney is supplied with 'blood from the renal art.; the right is larger than the left, its blood is returned by the renal vein, which opens on each side into the inf. vena cava. Its nerves are derived from the renal plexus formed from the lesser splanchnic, sympathetic, and solar plexus. The ureter, the excretory duct of the kidney, pro- ceeds from the pelvis of the kidney downwards and inwards, across the psoas muse., and iliac art. and behind the peritoneum ; it then sinks backwards into the pelvis, turns forwards, and comes in contact with the inferior surface of the bladder ; it runs forwards and inwards between the muscular and mucous coats of this viscus for a short distance, and finally opens into it at the posterior angle of the tri- gone vesicale. The ureter is crossed superiprly by the spermatic vessels, near its termination by the vas deferens in the male, and by the Fallopian tube and broad ligament in the female. The ureter is com- posed of nbro-mucous membrane ; the fibrous coat is well marked, its cavity is smallest at its termina- tion, largest at its commencement. The suprarenal capsules "are two yellowish bodies placed on the upper ext. of each kidney ; they are largest in the foetus, at which period they exceed the kidneys in size ; they degenerate into cellular tissue in the adult. 9* 102 STRUCTURE OP BLADDER. The bladder is lodged in the cavity of the pelvis, behind the pubes, in front of and above the rectum, and between the levatores ani muscles ; pyramidal in shape, its apex rounded, is directed upwards and forwards, its base, directed downwards and back- wards, rests on the lower extremity of the rectum, from whieli it i.s separated 'by the? prostate gland, ves- iculse scrambles, and vass, cteferentia: its anterior surface, somewhat flattened, is in contact with the pubes, its posterior with the recttfin and small intes- tines. ID t'ie female the uterus intervenes between the bladder and rectum. The bladder is composed of four coats, serous, mus- cular, fibrous, and mucous ; the serous coat is derived from the peritoneum, it is only a partial covering; the parts covered are the posterior half of superior fundus or apex, the posterior surface and the ante- rior portion of the lateral surfaces, the rest is un- covered by peritoneum; the muscular coat consists of three sets of fibres ; the longitudinal, best marked, are situated on the anterior and posterior surfaces, they unite at the superior fundus at the attachment of the urachus, and inferiorly are lost in the neck of the bladder; the oblique fibres are best marked pn the lateral surfaces, the circular surround the neck of the bladder. The fibrous coat of the bladder is well marked; the mucous coat lines the interior, it is of an irregular pinkish colour, and is generally thrown into folds in the collapsed state ; on it may be observed the orifices of the ureters ; immediately behind the neck of the bladder is a triangular space, pale and smooth, the trig one vesicale; its apex is at the orifice of the uretha, its base is formed by a line drawn from the orifice of one ureter to that of the other, its sides formed by lines drawn from them forwards to the apex, beneath them some muscular fibres are described. The liga- ments of the bladder are the false and true ; the false are folds of the peritoneum, and are five in number, THE URETHRA. 103 viz., two posterior, two lateral, and one anterior; the true are folds of the pelvic fascia, and are four in number, viz., two lateral, which pass off from the inner surface of the levator ani on the lateral surface of the bladder, and two anterior, which run from the neck to the back of the os pubis. The bladder is supplied with blood chiefly by the vesical branches of the int. iliac, its nerves are de- rived from the hypogastric plexus, and consists of spinal and sympathetic filaments. The urethra extends from the neck of the bladder to the orifice on the glans penis, about nine inches in length, it is divided into three portions, the prostate, membranous, and spongy. The prostatic portion is surrounded by the prostate gland ; about an inch and a half in length, it runs downwards and forwards, its cavity is wider in the centre than at its extremities ; on its lower surface is a projection of the mucous membrane, the caput gallinaginis or verumontanum, on the anterior margin of this is a depression, the sinus pocularis, and on each side of this a small orifice, the opening of the common ejaculatory duct, at the side of the verumontanum is a fossa, the prostatic sinus, on which a number of the prostatic ducts open. The membranous portion of the urethra lies imme- diately beneath the sub-pubic arch, from which it is separated by the sub- pubic ligament, the dorsal veins of the penis, and the apex of the triangular ligament ; about three-quarters of an inch in length, it is slightly curved; its cavity is smooth and small in size, its external covering is a dense fibrous membrane. The spongy portion of the urethra is that surrounded by the corpus spongiosum urethrse, it forms the remain- der of the canal; it commences posteriorly by a small dilatation, the sinus of the bulb, and terminates at the ext. orifice, the spongy portion dilates a little again behind the orifice forming the fossa navicularis, and then contracts to form the orifice a slit-like aperture 104 THE TESTES. on the glans penis. In the interior of this portion of the canal are numerous lacunae, one larger than the rest, locuna mayna, is situated near the fossa na- vicularis. The urethra in the female is short, about one inch and a-half in length, and opens externally beneath the clitoris between the nymphae minores, and immediately above the orifice of the vagina. SECTION VI. Male Organs of Generation. These consist of the testes, vasa deferentia, vesi- culse seminales, and penis. The testes are enclosed after birth in the scrotum, before this period they are placed a little beneath the kidneys, whence they descend into the scrotum. The scrotum is formed by a continuation of the com- mon skin, the dartos, superficial fascia, tunica corn- munis and tunica vaginalis. The skin of the scrotum is of a darkish brown and corrugated ; it presents on the mesial line the raphe ; the dartos is a thin layer of muscular fibres seldom well marked ; the superfi- cial fascia is continuous with that of the surrounding parts, it contains no adipose substance ; the tunica communis is'a layer of fibrous membrane derived su- periorly from the cremaster muscle, and continuous with the fascia investing the spermatic cord above; the tunica vaginalis is that layer of this membrane which passes from off the testis to the inner surface of the scrotum ; it thus forms a smooth cavity in which the testis is lodged. The scrotal or testal cavity on each side is distinct from the opposite one, being se- parated by the septum scroti, which is formed by are- flection inwards of the dartos, and the superficial fascia. The testes are contained in the scrotal cavities. Each testis is of an oval shape, the long axis being directed downward, backwards, and a little inwards, the outer surface is convex, the inner somewhat flat- VAS DEFERENS. 105 tened, the lower extremity is the smaller, the upper is capped by the head of the epididymis. It is com- posed of three coats, a serous, fibrous, and vascular. The serous coat is a portion of the tunica vaginalis ; this, originally a reflexion of the peritoneum, forms in the adult a distinct shut sac, lining the inner surface of the scrotum (tunica vag. scroti) and the outer sur- face of the testis (tunica vag. testis;) it is partial, and does not cover the testis on its back part, where the epididymis is attached and the vessels enter. The fibrous coat is the tunica albuginea. It is very dense, and of a whitish colour, the fibres interlace with each other, and send processes through the sub- stance of the testis, which, as they pass backwards, form an imperfect septum, mediastinum testis, and terminate in and form the corpus Highmorianum. Tunica vasculosa lines the internal surface of the preceding ; it is formed by a delicate network of vessels. The proper substance of the testis consists of an in- finite number of small tubes, tubuli seminiferi, which form a grayish pulpy mass ; they terminate in about twenty larger vessels which take a straight course, hence called tubuli recti, towards the back part of the testis ; they here form a network with the vessels and nerves of the testis forming the rete testis, lying be- tween the layers of the mediastinum testis ; from the upper and back part of this eight or ten vessels pro- ceed, called vasa efferentia, or coni vasculosi, and ter- minate in the head of the epididymis, forming one tube, the vas deferens; this is convoluted in a remark- able manner, and forms the epididymus ; this emerges from the globus minor, ascends along the inner edge of the epididymis, and forms part of the spermatic cords. The vas deferens ascends with this, passes along the inguinal canal, winds inwards at the inter- nal abd. ring, and then descends into the pelvis to the inner side of the hpyogastric art. and ureter, and 106 THE PROSTATE GLAND. reaches the inferior fundus of the bladder; it here runs forwards and inwards along the inner side of the vesicula seminalis, perforates the prostate gland and unites with the duct of the vesicula seminalis to form the common ejaculatory duct, and terminates on the verumontanum ; the vas deferens lies on the pos- terior part of the cord, where it may be distinguished by its whipcord-like feel. Its structure is fibro- mucous ; the fibrous coat is very dense ; the canal is extremely small, being not larger than a bristle. The spermatic cord is formed of the vas deferens, the spermatic art., veins, and nerves; it extends from the epididymis to the int. ring, where its com- ponent parts separate. The vas deferens proceeds as described. The spermatic art. ascends to its origin from the renal, the veins to the renal veins, and the nerves to the renal plexus and sympathetic nerve. The coverings of the cord have been described with hernia, the remains of the peritoneum covering the cord are sometimes described as the tunica vaginalis of the cord. The vesiculse seminales are situated 6ne on each side of the inferior fundus of the bladder to the outer side of the vas deferens; pyriform in shape, the larger extremity is directed backwards and outwards , the smaller forwards and inwards, terminates in a small duct which unites with the vas deferens, and terminates with it as just described. The structure of the VQsiculae seminales is fibro-mucous, its interior presenting a number of cells, with a central longitu- dinal canal. The prostate gland surrounds the neck of the blad- der and first portion of the urethra, which passes near to its upper surface, one-third of the gland being above, and two-thirds beneath this canal. The pros- tate gland is covered by the ascending layer of the tri- angular ligament of the urethra, and has attached to GLANS PENIS. 107 it anteriorly the anterior true ligaments of the blad- der which connect it to the pubic arch. The prostate gland is chestnut-shaped, the base posteriorly, the apex anteriorly ; it consists of three lobes, two lateral and a middle lobe ; the lateral are separated by a slight depression on its under sur- face, the middle lobe lies in and a little above the centre of the sulcus at its posterior extremity. This gland is composed of a number of mucous follicles, its ducts open into the prostatic portion of the urethra, the greater number on the sinus poculosus. The penis arises by two roots, the crura penis, one on each side, from the rami of the ischium and pubes ; these are conical in shape, pass forwards, converging, and unite to form the corpus cavernosum penis, which forms the body of the penis as far for- wards as the glans: as the corpus cavernosum is partially divided by an imperfect septum, it may be considered as consisting of two lateral portions. This body is covered exteriorly by a dense fibrous structure, which forms the septum, within which is a peculiar erectile tissue composed chiefly of ar- teries. The penis presents on its upper surface a slight depression, in which are lodged the dorsal vessels and nerves ; on its under surface is a larger depression, giving lodgement to the corpus spongio- sum urethrae ; it is covered by a delicate thin skin, which anteriorly forms the prepuce, connected to the under surface of the glans by the frsenum preputii; where this is reflected on the corona glandis, a num- ber of sebaceous follicles, glandulse Tysoni, are found. The glans penis is formed altogether by the corpus spongiosum urethrae. The penis is supplied with blood by its dorsal and cavernous vessels ; branches of the int. pubic; its veins pass backward beneath the sub-pubic arch, and form a network around the prostate gland, and terminate in the int. iliac ; its nerves are derived from the int. pubic. The corpus 108 MUSCLES OF THE PERINEUM. spongiosum is supplied by the the art. of the bulb, a branch also of the int. pubic : its structure is also erectile, and seems to be chiefly composed of veins. SECTION VII. The PerinsBum is a diamond-shaped space situated between the thighs on each side, the scrotum and sub-pubic an- gle in front, and the os coccygis behind. In this is included the' anal region, properly so called, which occupies the posterior triangle, whilst the proper periuaeum occupies the anterior. The lateral boun- daries of the perinasum are on each side the rami of the ischium and pubes, the tuber ischii, and the edge of the glutseus maximus muscle, and, more deeply, the great sacrosciatic ligament. The integuments of this region are thin, of a brownish color, and present on the mesial line a fold termed the raphe. This commences at the anus, and may be traced as far forwards along the mesial line of the scrotum as the root of the penis. Be- neath the integuments is a quantity of loose cellular tissue, the superficial fascia of the perinaeum, con- tinuous on either side with the superficial fascia of the thighs, in front with that of the scrotum, and posteriorly with the adipose tissue filling up the large space at the side of the rectum. Beneath the superficial fascia is the perinxal fascia; this is much more dense than the preceding, and is firmly attached on each side to the rami of the ischium and pubes ; anteriorly it is lost on the scrotum, and posteriorly is continuous with the adipose tissue surrounding the rectum. Beneath this lie The Muscles of the Perinseum. Transversus Perinsei. Or. from the inner surface of the tuber, ischii, above the erector penis m. DEEP PERIN^AL FASCIA. 109 Ins. into the central point between the accelerator urinae and sphincter ani m. .-. these two muscles correspond to the transverse line just referred to . . one or two more m. (T. P. Alteri) sometimes pass upwards and inwards to the accelerator urinae m. Use, to fix the central point of the perinaeum. Accelerator urinse. Or. 1, the central point and two inches of the fibrous raphe* running from it along the corpus spong. ; 2, from the post, part of the tri- angular ligament. Ins. 1, the posterior fibres into the inner side of the crus penis; 2, the middle by distinct aponeurotic fibres into the groove between the two corp. cavernosa, commencing at the junction of the two crura ; 8, the anterior pass upwards and forwards over the corp. cavern., and are ins. into the suspensor lig. of the penis.-. The ant. fibres com- press the dorsal veins of the penis. (Houston.) Use, to compress the bulb and corpus spongiosum urethrae, and to expel their contents, whether urine or semen ; hence called ejaculatores seminis. Erector penis Or. 1, fleshy and tendinous from the inner edge of the tuberosity of the ischium, and root of the crus penis. Ins. by a tendinous expansion into the fibrous membrane of the corpus cavernosum. Use, to erect the penis by forcing the blood forwards. The whole of these muscles being removed, the crura penis detached, and the urethra cut through in front of the bulb, and reflected backwards, the deep perinseal faschia or triangular ligament of the urethra is exposed. This is a dense fibrous layer closing up the anterior triangle of the perinaeum. On each side it is firmly attached to the rami of the ischium and pubes, and tuber ischii, and is here continuous with the outer layer of the pelvic fascia. Its apex, turned forwards, passes above the urethra, splits into two layers, enclosing the sub-pubic ligament, and lost on the surface of the pubes ; its base, turned backwards, 10 110 MUSCLES OF PERINEUM. is crescentic to accommodate the concavity of the rectum, and is lost on tUe surfaces of this intestine. The triangular lig. is perforated near the centre by the memb. portion of the urethra, which passes through it from above downwards and forwards. As the urethra passes through, the ligament sends off two layers, the ascending and descending. The ascending passes upwards and backwards, and is lost on the capsule of the prostate gland ; the descending passes downwards and forwards, and is lost on the fibrous covering of the corpus spongiosum urethrse. In the angle between this and the bulb lie two small glands, Cowper'z glands, which open by small ducts on the interior of the bulb. The posterior triangle of the perinseum is occupied by the anus and lower ext. of the rectum. Around the anus is the Sphincter ani muscle. Or. from the extremity of the coccyx; its fibres surround the anus, and are Ins. into the central point of the perinaeum. Use, to close the anus. At each side of the rectum is a large space occu- pied by a quantity of adipose tissue ; on removing this, the following muscle is exposed Levator ani. Or. 1, from the posterior part of the symphysis pubis, below the true ligaments of the blad- der ; 2, from the obturator fascia, and from the ilium above the thyroid foramen, by means of the pelvic fascia; 3, from the inner surface and spine of the ischium, the fires converge, and are Ins., the anterior fibres into the central point of the perinseum and fore part of the rectum, the middle into the side of the rectum, the posterior into the back part of the rec- tum and the sides of the os coccygis. Use, to raise and draw forwards the lower ext. of the rectum ; also to assist the expulsion of the urine and semen. The anterior fibres of this muscle are sometime* NYMPHS. Ill described as Wilson's muscles ; a few of its fibres are also described as Guthries muscles. Behind the levator ani is the Coccygeus. Or. narrow from the inner surface of the spine of the ischium. Ins. into the side of the coccyx. The arteries met with in the perinseum are the transversus perinsei, perinaeal, and the art. of the bulb, branches of the int. pudic. Around the anus are the inferior hemorrhoidal arteries. The nerves proceed from the int. pubic and sciatic. SECTION VIII. The Female Organs of Generation are divided into the external and internal. The ex- ternal are the mons veneris, vulva, labia, clitoris, nym- phce,, and vagina. The mons veneris is the eminence on the anterior surface of the pubes. The vulva is the slit-like aperture between the labia. The labia externa, or majora, are the folds of integument on each side of the vulva ; they commence at the mons veneris, and terminate posteriorly in the commissure or fourchette, behind which is the fossa navicularis; their struc- ture is composed of skin externally, mucous mem- brane internally, enclosing some cellular vascular tissue. The nymphce, or labia minor a descend out- wards from the prepuce of the clitoris, and are lost about the centre of the vulva on the labia majora ; the orifice of the urethra lies between them. The clitoris is analogous to the male penis ; it is covered ante- riorly by an irregular prepuce, continuous interiorly with the nymphss. It contains no canal. M. Huguier has recently described two glands, situated one on each side and within the vagina, which opens by ducts near the margin of the hymen. 112 FALLOPIAN TUBES. The vagina is the canal leading from the vulva upwards and backwards to the uterus ; it is slightly curved, the concavity towards the pubes, and passes between the urethra and bladder above, and the rec- tum behind ; at its internal extremity it surrounds the neck of the uterus, passing farther on its poste- rior than anterior surface. The structure of the vagina is composed exteriorly of an erectile vascular tissue lined by mucous membrane : this is irregular, and presents near the orifice the hymen, a crescentic fold, the remains of which form the cunmculw myrti- formes; this membrane possesses a number of mucous glands and follicles. The internal organs of generation in the female are the Uterus, Ovaries, and Fallopian tubes. The Uterus is situated in the pelvis, between the bladder and rectum ; pyriform in shape, its superior fundus larger, is turned upwards and forwards, its inferior fundus directed a little backwards is round- ed, and terminates by a slight expansion, behind which is the cervix uteri ; the anterior and posterior surfaces somewhat flattened, are partially covered by peritoneum; its edges rounded afford attachment to the broad ligaments, and at the superior extremity to the Fallopian tubes and ligaments of the ovary. The structure of the uterus is composed of an ex- ternal serous partial covering from the peritoneum, beneath which is a peculiar firm tissue, about half an inch in depth, dense as cartilage, and composed chiefly of muscular fibres ; its interior is lined by mucous membrane. The cavity of the uterus com- mences at the os or mouth; this is a transverse aper- ture, hence os tincce, which leads into the general cavity ; this widens a little in the centre, and branches off on either side, and superiorly into a small canal which leads into the Fallopian tubes. The Fallopian tubes, one on each side, proceed from the superior and lateral portion of the uterus out- LIGAMENTUM TERES. 113 wards to the extent of about four inches, contained in the broad ligament, and terminate in an irregular expansion, the corpus fimbriatum ; the cavity of the Fallopian tube is small, and terminates on the corpus fimbriatum by a small aperture, morsus diaboli. The Ovaries, or female testes, are attached also to the superior end of the uterus immediately behind the Fallopian tubes. They are contained in the broad ligament, and are attached to the uterus by an imper- vious ligament. The ovaries are covered by perito- neum, beneath which is a fibrous coat; the interior is composed of a number of vesicles ; Graafian vesi- cles, from six to ten or twelve on each side. The Uterus is supplied with blood by the uterine arts, from the int. iliac ; its veins terminate in the int. iliac veins; its nerves are derived from the sym- pathetic. The ovaries receive their supply of blood from the spermatic arteries. The Ligamentum teres is an analogue to the sper- matic cord in the male, although it does not perform any special function. It is composed of cellular tis- sue, nerves, &c., and stretches from the upper ext. of the uterus, in front of the Fallopian tubes, to the labium pudendi. The Perinseum in the female is comparatively un- important; it extends from the fourchette back- wards to the anus, and has muscles analogous to those in the male. 10* 114 CHAPTER V. THE INFERIOR OR LOWER EXTREMITIES. are connected to the trunk by numerous muscles and ligaments; the former extend from the pelvis and spine, the latter from the ligaments of the hip-joint. Beneath the integuments covering the lower extre- mities is found a quantity of superficial fascia, or loose subcutaneous cellular tissue. It contains nu- merous superficial blood vessels, nerves and lympha- tic glands, of these the largest is the int. saphena vein, which may be traced from the foot upwards to its termination in the femoral vein. The arteries are chiefly branches from the femoral, the nerves from the anterior crural and lumbar plexus. Beneath this is a dense layer of fascia, the fas- cia lata, the strongest in the body, which not only invests the muscles, but sends septa in between them. (See Fasciae.) Muscles of the Lower Extremity. Of the Hip-Joint, 7. Gluteus Maximus, Or. 1, post, fifth of the crista ilii, and rough surface beneath it, down to the super, semi- circular ridge; 2, from the lumbar fascia and sacro- iliac ligaments; 3, from the sides of the sacrum and coccyx and post, sacro-iliac ligament; 4, from the fascia of the gluteus medius. Ins. by a flat thick tendon into an irregular longitudinal surface, leading from the great trochanter to the linea aspera of the femur, and into the fascia lata just below. . Use, to extend, abduct, and rotate the thigh outwards ; to make tense the fascia lata, and to fix the pelvis on the lower extremity. ADDUCTORS. 115 Glutens medius, Or. 1, from the ant. three-fourths of the christi ilii, and ant. sup. spinous process; 2, from the surface of the ilium between its two curved lines. Ins. into the outer part of the great trochan- ter. Use, to abduct the thigh; the posterior fibres rotate the limb outwards, the anterior inwards. Glutens minimus, Or. from the inf. curved line and surface of the ilium down to the sup. margin of the acetabulum ; Ins. ant. half of the margin of the great trochanter. Use, similar to the last. Pyriformis, Or. 1, by three slips from the ant. sur- faces of the second, third, and fourth divisions of the sacrum ; 2, from the ant, surface of the great sciatic ligament, and upper edge of the notch, Ins. post part of the margin of the great trochanter. Use, to abduct and rotate the thigh outwards. Obturator internus, Or. 1, from the inner surface of the obturator fascia and fibrous arch of the obt. vessels ; 2, from the bony margin of the foramen and surface of the ischium, between it and the sciatic notch ; 3, from the upper edge of the true pelvis. Ins. into the digital fossa. Use, to abduct and rotate the thigh outwards. Gemelli, (accessory fibres of the obt. int.) Or, the upper one, from the spine of the ischium ; the lower one, from its tuberosity ; they enclose the obt. ten- don, into which, and into the digital fossa, they are inserted ; the upper one is sometimes absent. Use, to abduct and rotate the thigh outwards, . Obturator externus, Or. ant. and lower part of the obturator membrane, and corresponding portions of the margin of the foramen ; its tendon passes in a groove between the tuber ischii and the edge of the acetabulum, winds around the neck of the femur, to be Ins. into the digital fossa below the other mus- cles. Use, to abduct and rotate the thigh outwards. The abductor and external rotator muscles of the thigh are 7 in number, and arise successively in a line 116 ADDUCTOR LONGUS. %, which may be traced along the sides of the lumbar vert, crista ilii, pectineal line, body and ramus of the pubis, and remus and tuberosity of the ischium. Psoas minor, Or. sides of the bodies of the last dor- sal and the first (and sometimes the second) lumbar vertebrae : its narrow tendon expands to be Ins. into the ilio-pectineal line, and, by its outer edge, into the fascia iliaca : it tenses that fascia, and, by thus confining the two following muscles in their places, may be deemed their accessory. It also acts upon the vert, column and pelvis. Psoas magnus, Or. by slips, the intervals between which give passage to the spinal nerves, from the sides of the bodies and intervert. substances of the last dorsal and the five lumbar vert., and from the roots of the corresponding transverse processes ; Ins by a tendon equally shared by the iliacus, into the smaller trochanter. The lumbar plexus of nerves is imbedded in its substance. Use, to flex the thigh and rotate it outwards, to bend the body forwards. Iliacus, Or. 1, from the margin and the entire sur- face of the iliac fossa ; 2, from the two ant. spinous processes : 3, from the base of the sacrum ; 4, from the capsule of the hip-joint. Ins. with the tendon of the psoas mag. into the smaller trochanter. Use, to flex and rotate the thigh upwards. These two muscles pass in front of the capsular lig. of the hip- joint, from which they are separated by a large buBsa mucosa. Pectineus, Or. 1, from the spine of the pubis and the pectineal line ; 2, from the inf. surface of an apo- neurosis continued from Gimbernaut's ligament. Ins. into the commencement of a line leading from the trochanter minor to the linea aspera ; separated from the psoas by the femoral artery, as it lies in front of the quadratus femoris. Use, to adduct, flex, and rotate the thigh outwards. Adductor longus. Apparently continuous at its origin with the pectineus, Or. by a flat tendon from SARTORIUS. 117 the spine of the pubis; Ins. into the middle third of the linea aspera, in front of the abductor magnus. Abductor Brevis, Or. body of the pubis below the spine and between the gracilis and obturator exter- nus; Ins. in front of the abductor magnus, into the line leading from the trochanter minor to the linea aspera, below the Ins. of the pectineus. The three last muscles lie on a plane anterior to that occupied by the two following, Adductor magnus, Or. 1, ramus of the pupis and ischium; 2, lower part of the tuberosity of the ischium. Ins. fleshy into the whole length of the middle ridge of the linea aspera, and into a line leading from it to the great trochanter above, and to the inner condyle below ; 2, by a tendon into a tubercle on the post, and upper part of the inner condyle. An opening exists, between the two portions, at the lower third of the thigh, formed especially for the transmission of the femoral vessels, to the sheath of which its edges are united. Use, the three adductors adduct, flex and rotate the thigh outwards. Quadratus femoris, quadrilateral, Or. from the outer edge of the tuberosity of the ischium, and, frequently, from the ramus of that bone. Ins. into the line leading from the trochanter major to the linea aspera : it ap- pears to be a continuation of the ad. mag. , from which it is only separated by the int. circumflex artery. Use, to adduct and rotate the thigh outwards. Muscles of the front and sides of the thigh, No. 7. Tensor vaginse femoris, Or. by a tendon, from the crista and ant. sup. spinous process of the ilium be- tween the sartorius and glutaeus medius; it is also at- tached to the aponeurosis of the latter muscle; it de- scends slightly backwards to the Ins. between two lamellae of the fascia lata, at about the upper third of the thigh. Use, to make tense the fascia, and rotate the thigh inwards. 118 VASTUS INTERNUS. Sartorius, Or. ant. and sup. iliac spinous process, with the tensor fascia, and from half of the interspi- nous notch. Its tendon expands to be Ins. into the crista of the tibia, just below its tuberosity; its ex- pansion covers the tendons of the gracilis and semi- tendinosus; it also strengthens the fascia of the leg. Use, to flex the thigh, adduct and rotate it inwards ; also to flex the leg on the thigh obliquely so as to cross over the opposite limb. Gracilis, Or. by a thin tendon, from the inner part of the pubis symphysis, from the spine, to the ramus of the ischium, internal to the abductor magnus. Ins. into the crista of the tibia, above the semi-tendinosus. The spreading of these muscles at their insertions is termed by the French anatomists, patte d' Oie. Use, to adduct the leg and thigh, to bend the knee, and turn the leg inwards. Quadriceps extensor. Rectus femoris, Or. 1, by a straight tendon from the inf. iliac spinous process ; 2, by a reflected tendon from a fossa, just above the edge of the acetabulum. Ins. by a strong tendon which it shares with the vast! and crureus, into the ant. surface, and edge of the upper half of the patella. Use, to extend the leg on the thigh, to flex this on the pelvis. Vastus externus, Or. 1, base and ant. part of the great, trochanter; 2, from the tendinous ins, of the gluteus max. and short head of the biceps, and from the outer edge of the whole length of the linea aspera. Ins. into the external side of the common tendon and the patella: it covers the ext., part of the crureus at its origin. Use, to extend the knee, and rotate the , leg outwards. Vastus internus, Or, I, inter-trochanteric line, and whole length of the inner edge of the linea aspera, 2, inner surface of the femur. Ins. into the inner edge of the common tendon, and the patella, and by an aponeurosis, which covers the inner side of the knee- SEMIMEMBRANOSUS. 119 joint into the head of the tibia. Use, to extend the knee and rotate the leg inwards. Cmreus, inseparable from the last m., Or. fleshy from the ant. and ext. surface of the upper three- fourths of the femur, commencing at the ant. inter- trochanteric line. Ins. upper edge of the patella with the common tendon, and into the synovial mem- brane behind it. A large bursa, which sometimes communicates with the joint, is placed between its tendon and the femur. The common tendon before it reaches the patella, is separable into three portions: the anterior one belongs to the rectus, the middle to the vastus externus, and the last to the vastus in- ternus and crureus. The ligamentum patella con- tinues them from the anterior surface and margin of the lower half of the patella, to the tuberosity of the tibia. Use, to -extend the knee. Muscles on the posterior part^of the Thigh, 3 Flexors. Biceps, flexor cruris, Or. 1, by its long head, in com- mon with the semitendinosus, from the outer and posterior margins of the tuber ischii, immediately below the inferior gemellus,- 2, by its short head from the linea aspera, from the ins. of the gluteus maximus, to within two inches of the outer condyle. Ins. head of the fibula. Its tendon also expands, to strengthen the ext. lat. lig. and fascia of tfre leg. Use, to flex the knee, the long head will extend the thigh and rotate the limb outwards. Semitendinosus, Or. tuber ischii, with the long head of the biceps. Ins. into the crest of the tibia, be- neath the expanded tendon of the sartorius, and below the tendon of the gracilis, to which it is joined. Use, to flex the knee and rotate the leg in- wards; to extend the thigh. Semimembranosus, Or. outer part of the tuber ischii, in front of the biceps and semitendinosus. Ins. back part of the inner tuberosity of the tibia: from this 120 ARTERIES AND NERVES. point a process is sent diagonally across the joint, to the inner part of the ext. condyle, so as to form the greater part of the lig. posticum; another winds, in a groove lined by synovial membrane, horizontally round the inner tuberosity of the tibia, into which it is inserted; and a third expands over the popliteus m. Use, to extend the thigh, to flex the knee, and rotate the leg inwards. In the dissection of the anterior part of the thigh, the great vessels and nerves, viz., the femoral art., vein, and anterior crural nerve are found. The Femoral Art. is the continuation of the ext. iliac; it passes beneath Poupart's ligament, having the vein to its inner side, the ant. crural nerve to its outer side and at some distance from it ; from this the femoral art. passes downwards, backwards, and inwards, and finally escapes beneath the adductor magnus tendon into the popliteal space, and assumes the name of popliteal art. ; its principal branch is the profunda ; the femoral vein accompanies the art., at first lying internal to it, and then getting pos- terior to it. The anterior crural nerve descends into the thigh between the psoas magnus and iliacus internus muscles, and soon divides into a lash of filaments to supply the principal muscles on the an- terior and lateral surfaces of the thigh; its most im- portant branch is the int. saphenous nerve, which accompanies the femoral art. in its lower third, and leaves it to descend with the anastomotica magna to the knee, below which it joins the int. saphena vein. The arteries met with on the back part of the hip and thigh are the gluteal, sciatic and pudic branches of the internal iliac ; the first two descends into the thigh, the last is lost about the perinaeum and or- gans of generation. The nerves are the great and lesser sciatic nerves, branches of the sacarl plexus. MUSCLES OF LEG. 121 SECTION I. Of the Leg. Beneath the integuments of the leg, as in most other parts of the body, is found the superficial fas- cia; in it are contained, on the inner side the int. saphena vein and saphenous nerve; on the posterior surface the ext. saphena vein and post, saphenous nerve, will be found, but beneath the fascia of the leg at its upper part. Beneath the superficial fascia is a strong aponeu- rosis, the fascia of the leg, attached on either side to the spines of the tibia and fibula. On raising this will be found the Muscles of the Leg, 13. Those in Front, 3 Tibialis anticus, Or. 1. from the upper two-thirds or the ext. surface and crista of the tibia, as far as the outer tuberosity ; 2, from the inner half of the interosseous ligament, from the fascia of the leg and septa. Ins. into a tubercle on the first cuneiform bone, and base of the first metatarsal bone. Use, to flex the ankle, adduct the foot, and to raise its inner edge from the ground. Extensor communis digitorum, Or, 1, from the outer tuber tibise, with the tibialis anticus; 2, from the whole length of the surface of the fibula, in front of the interosseous ligament, and slightly from that lig., from the crural fascia and septa. Ins. by four ten- dons, into the phalanges of the four lesser toes, like the corresponding m. of the arm. The outer fibres of the inf. third of the muscle are attached to a fifth tendon. Use, to extend the toes and flex the ankle. Extensor proprius pollicis, Or. middle third of the ant. surface of the fibula covered by the last m., slightly from the interosseous ligament, from the crural fascia and septa ; Ins. by two fasciculi into 11 122 GASTROCNEMIUS. the first and second phalanges. Use, to extend the great toe and flex the ankle. Muscles on the outer part of the Leg, 3. Peroneus longus, Or. 1, outer and fore part of the head of the fibula, and ext. surface of the upper two- thirds of that bone ; 2, slightly, from the inner tuber tibiae, with the common extensor from the crural fascia and septa. Ins. into a tubercle on the outer part of the base of the first metatarsal bone ; its ten- don crosses the foot above all the other soft parts, lodged in a groove in the cuboid bone. Use, to ex- tend the ankle, turn the foot outwards, and raise its outer edge. Peroneus brevis, Or. lower half of the outer and posterior surface of the fibula ; Ins. base of the fifth (sometimes also of the fourth) metatarsal bone. Use, similar to the last. Peroneus tertius. The external fibres of the lower third of the ext. com. m. terminate in a tendon which is ins. into the upper surface of the fifth metatarsal bone, just in front of the last muscle. Use, to flex the ankle, raise its outer edge, and abduct the foot. Muscles on the back of the Leg, 1. Superficial set, 4. Gastrocnemius, Or. by two heads, each of which is attached to a depression on the upper, outer, and back part of each condyle, and condyloid ridges; the in- ner one, the larger, just behind the tendon of the abductor mag.; the outer one, just above the tendon of the popliteus. The resulting two fleshy bellies are united in a raphe, a little below the joint, and terminate at the middle of the leg, in a flat tendon, which almost immediately becomes a part of the tend. Achillis. Use, to extend the ankle-joint, to raise the body in walking, to flex the knee-joint. FLEXOR COMMUNIS. 123 Plantaris, Or. ext. condyloid line, and fibrous cap- sule over the outer condyle ; its long narrow tendon runs to the inner edge of the tendo Aehillis, to be Ins. into the calcaneum, or merely into the fatty tis- sue, before the insertion of that tendon. Sometimes double. Use, to aid the preceding. Soleus, Or. 1, tendinous, from the inner and back part of the head of the tibia, and aponeurotic, from the post, surface and outer edge of the upper third, of the fibula ; 2, from the popliteus fascia post, obli- que line of the tibia, and from a third of its inner edge: just below, its tendon, with that of the gas- trocnemius, forms the tendo Aehillis, which is Ins. into the lower, and back part of the calcaneum. Use, to extend the ankle and assist the progression by raising th'e os calcis from the ground. Popliteus, Or. narrow, from a fossa on the back part of the outer condyle of the femur ; Ins. broad, into all the triangular surface of the tibia, above its oblique line: the tendon is covered by the ext. lat. ligament, and surrounded by the synovial membrane of the joint. Use, to flex the knee, and when flexed to turn the leg inwards. Deep set, 3. Tibialis posticus, lies in the posterior interosseous space ; Or. by two fleshy slips, between whicli passes the ant. tib. art. ; one from the oblique line of the tibia, below the popliteus, soleus, and common flexor; the other from the inner edge of the fibula, below the soleus; also, the whole of the interosseous ligament, and adjoining surface of the fibula. Ins. with a se- samoid bone into a tubercle on the inner side of the scaphoid bone. Use, to extend the ankle, and raise the inner edge of the foot from the ground. Flexor digitorum communis perforans, Or. posterior surface of the tibia, between the oblique line and a point two inches above the inner malleolus ; Ins. into 124 SOLE OF FOOT. the last phalanges of the four smaller toes, like the corresponding muscles of the fingers. Use, to flex the toes, to extend the ankle, and assist in raising the body from the ground in progression. Flexor pollicis pedis, the largest muscle of this set, Or. inf. two-thirds of the post, surface of the fibula: Ins. into the last phalanx of the great toe, like the corresponding muscle of the thumb. Use, to flex the great toe and extend the ankle. Muscles of the Foot. Of the Dor sum, 1. Dorsalis pedis, Or. from the outer and upper part of the calcaneum, and adjoining portion of the ext. calcaneo-cuboid ligament ; Ins. by four tendons, of which the three last are ins. into the expansion of the common extensor tendons on the first phalanges of the second, third, and fourth toes, and the first into the base of the first phalanx of the great toe. Use, to extend the four inner toes. The Sole of the Foot. The integuments covering the sole of the foot arc remarkablydense, particularly where exposed to pres- sure, as on the heel and outer side of the foot ; beneath these is a thick layer of adipose substance, collected into small masses so as to form an elastic cushion to preserve the subjacent parts from injury in progres- sion; beneath this is a dense layer of fibrous tissue, the plantar aponeurosis ; triangular in shape it is attached posteriorly by its apex to the tubercles on the os calcis, passes forwards, spreads out, and divides into three portions; of these the central is the strongest, the outer the next in strength, and the inner the weak- est ; these send in processes between the muscles; the lateral are attached to the sides of the tarsus and me- tatarsus, the central portion divides anteriorlyinto five MUSCLES OP FOOT. 125 fasciculi, which again subdivide, and are attached to the lateral ligaments of the metatarso-phalangeal ar- ticulations, leaving intervals for the passage of the digital tendons, vessels, and nerves. Beneath this are the Planter Muscles* 19. Of the Inner Edge, 4. Abductor pollicis, Or. 1, from the inner tubercle of thecalcaneum; 2, from the int. annular lig. and plantar fascia. Ins. into the int. sesam. bone of the base of the first phalanx of the great toe, with the inner head of the flexor brevis. Use, to abduct the great toe. Flexor brevis pollicis, Or. from the two last cunei- form bones, and from the ant. part of the calcaneum and their ligaments ; Ins. by two heads with the ab- ductor and adductor pollicis, into the sesamoid bones and base of the first phalanx. Use, to flex the first joint of the great toe. Adductor pollicis is placed in the hollow formed by the lower surfaces of the four last metatarsal bones ; Or. cuboid and bases of the three last metatarsal bones, and from the sheath of the peroneus long, tendon ; Ins. with the outer head of the last m. into the ext. sesamoid bone. Use, to abduct and flex the great toe. Adductor secundus vel transversus pedis, Or. from the head of the last metatarsal bone, and phalangeal ligaments of the two next ; Ins. outer edge of the first phalanx of the great toe, close to the last muscle. Muscles of the outer Edge of the Foot, 2-3. Abductor minimi digiti,-Or. from the ext. tubercle of the'calcaneum, and sometimes from the base of the last metatarsal bone ; Ins. outer side of the base of the first phalanx of the little toe. Use, to abduct and flex the little toe. Flexor digiti minimi resembles an interosseous m. Or. base of the fifth metatarsal bone and adjoining li- 126 RELATION OP PARTS. gaments; Ins. on the outer part of the base of the first phalanx. A few fasciculi from the same origins may sometimes be traced to the whole of the outer edge of the fifth metatarsal bone. These might be called opponens digiti minimi. Use, to flex and adduct the little toe. Muscles in the Middle of the Foot, 13. Flexor brevis perforatus, Or. 1, from the calcaneum, between the tubercles ; 2, from the plantar fascia, and septum on each side. Ins. by slips, into the four smaller toes, like the flexor perforatus of the hand. Use, to flex the four outer toes. Flexor accessorius, Or. inferior surface of the cal- can., and calcan. scaphoid ligament ; Ins. 1, into the outer edge of the tendon of the common flexor; 2, strengthened by a process from the tendon of flex, long, pol., into the upper surfaces of each tendon of the common flexor. Use, to flex the toes with or without the long flexor. Lumbricales resemble precisely the corresponding fasciculi in the hand. Use, to adduct and flex the four outer toes. The Interossei are seven in number, as in the hand ; viz., four dorsal and three plantar, the former being abductors, the latter adductors; but, in the foot, the median line, or axis of the second toe, must be taken as the fixed point. The first dorsal interosseous muscle is attached to the tibial side of the second toe; the second to the fibular side of the same toe; the third, to the fibular side of the third toe ; the fourth, to the fibular side of the fourth toe. The plan- tar are attached, the first, to the tibial side of the third toe; the second, to the tibial of the fourth toe; the third, to the tibial side of the fifth or little toe. The relations of the parts about the ankle joint, are as follows: A. Posteriorly, 1, the inner malleolus, and the groove and sheath containing the tendons of the tibialis posticus and common flexor ; 2, the tendon of the flexor pollicis, which lies close to the calcaneum, ARTERIES OF LEG AND FOOT. 127 separated by a space of an inch and a quarter from the last-named tendons; 3, the post, tibial vessels and nerve in the middle of this space, or somewhat nearer the flex. pol. tendon, and superficially, the intern, saphen. nerve and vein; 4, the tendon of theplantaris, tendo Achillis, and tuberosity of the calcaneum ; 5, the communicans tibiae, nerve, ext. saphena vein, and more deeply, the termination of the peroneal artery; 6, the ext. malleolus, and immediately behind it, the tendons of peronei long et brevis, in a single groove and sheath. B. Anteriorly, 1, the tendon of the tibialis anticus; 2, that of the ext. pollicis; 3, surfaces of the tibia and astragalus supporting the ant. tibial artery and nerve ; 4, tendons of the common extensor, and tendon of the peroneus tertius. In the dissection of the leg and foot, the principal vessels and nerves met with are the anterior and posterior tibial and their several branches. The femoral art. having entered the popliteal space assumes the name of popliteal ; this descends nearly in the centre of the space, and at the lower margin of the popliteus muscle divides into its two terminating branches, the anterior tibial, the smaller, and the pos- terior tibial. The anterior tibial art. passes forwards through the interosseous space and descends on the anterior surface of the interosseous membrane, passes beneath the anterior annular ligament of the' ankle- joint, runs forwards and inwards to the cleft between the first and second metatarsal bones, and sinks into the sole of the foot to anastomose with the plantar ar- teries; it is accompanied in the lower two-thirds of its course by the ant. tibial nerve, a branch from the pe- roneal or fibular. The posterior tibial art. descends obliquely inwards along the posterior surface of the leg, resting on the deep muscles, passes behind the internal malleolus, enters the sole of the foot, and terminates in the ext. and int. plantar arteries, of these the external is the 128 ARTERIES OP LEG AND FOOT. larger and supplies three and a half toes from the little toe inwards, the int. plantar art. supplies the one and a half inner toes. The posterior tib. art. is accompanied by the post, tib. nerve, which terminates like it in the side of the foot in two plantar nerves; of these the internal is the larger, and supplies the three and a half inner toes, the ext. supplies the remaining one and a half toes. Shortly after its origin, the post. tib. art. gives off its largest branch, the fibular; this descends out- wards along the back of the fibula, and terminates about the ankle-joint. It is not accompanied by any 129 CHAPTER VI. Superficial fascia. An areolar tissue, connected by numerous filaments to the dermis ; its principal use is to render the skin movable on the subjacent parts, and to protect the subcutaneous vessels and nerves ; it may also be considered as the connecting medium between the skin and aponeurosis. The subcutaneous cellular tissue, superficial fascia, and the proper in- vestment of muscles, tendons, &c., are modifications of the same tissue, and in some regions it is difficult to tell where the one begins or the other ends ; in others the investing fasciae are sufficiently distinct, but no line of demarkation distinguishes the subcuta- neous tissue from the so-called superficial fascia, the separation is always more or less arbitrary: thus, in the inguinal region, where it forms a layer of some importance, the adipose substance and cellules, so frequently developed in large quantities beneath the skin, must always be cut through, in raising the latter membrane, in order to demonstrate a superfi-. cial fascia. Fascia, aponeurosis. These terms are almost indis- criminately employed to designate those layers of con- densed cellular membranes, which, as sheaths> septa, or linings, preserve the various organs of the body in their forms and relations. The fascia transversalis is an example of the latter, and the fascia lata is the best specimen of a sheath. This fascia surrounds the whole inferior extremity, and sends numerous pro- cesses or septa from its inferior surface, some of which form secondary sheaths for the muscles, vessels, and nerves of the limb. If all these organs could be re- moved without injury to an aponeurotic investment of this kind, a faithful outline of their form and relative position would still remain; in fact, the whole body, 130 ABDOMINAL FASCIAE. if it could be subjected to such a process, would re- present a skeleton of cavities and tubes, admirably adapted for the protection and support of their re- spective organs. Fascia cervicalis (superficialis.) The superficial fascia of this region contains a cutaneous muscle, the platysma myoides; it may be traced from the median line completely round the neck ; above, it is lost with the platysma on the face ; and below, on the muscles of the chest; on the sterno-mastoid muscle it is identified with the next fascia ; both are inti- mately united elsewhere, but can be separated with- out much difficulty. Fascia cerv. profunda. A dense aponeurotic line extends from the symphysis of the chin to the os hyoides, and onwards to the inner part of the first bone of the sternum: from each side of this line the fascia may be traced round the neck to its posterior part. It furnishes a sheath for the sterno-mastoid muscle, and another for the submaxiliary gland, which is thus separated from the parotid ; its processes form a sheath for the carotid artery, jugular vein, and va- gus nerve, another for the omo-hyoid muscle, by which it is enabled to preserve its angular directions, and several less remarkable for the remaining organs, lym- phatics, &c., in this region. A layer separates the sternal muscles from the trachea, and descends to be connected with a dense tissue, which so strongly ties the great vessels to the inside of the sternum ; accord- ing to Todd and Bowman, it even reaches the pericar- dium: above, the deep cervical fascia is attached to the base of the jaw, and the stylo-maxiliary ligament, and over the parotid to the zygoma; below, to the in- ner side of the clavicle and first bone of the sternum. Abdominal Fascise and Aponeurosis. The superficial fascia deserves most attention in the inguinal and crural regions ; there it presents a well- LIGAMENTUM ARCUATUM. 131 developed layer, which is strongly adherent a little below Poupart's ligament; it descends on the thigh, and, on the cord and testicle, to form one of the scro- tal coverings. In early life it is said to occupy the inguinal canal, as a gubernaculum for the descent of the testis. Its crural portion is loaded with lympha- tic glands and small vessels. Sheath of the Rectus. The int. obliquus muscle ter- minates in an aponeurosis, which at the linea semilu- naris is intimately united to that of the transversalis m., and then splits into two layers; one, closely united to the aponeurosis of the ext. oblique, passes to the linea alba in front of the rectus ; the other, with the aponeurosis of the transversalis, to the same line behind that muscle : but where the rectus covers the ribs, and from a point midway between the umbili- cus and pubes to the pubes, the sheath wants its post, paries, inasmuch as the four conjoined aponeu- roses there pass in front of the m,uscle. Sheath of the quadratus lumb., lumbar fascise. At the outer edge of the quadratus m., the inter, oblique and transversalis also terminate in one aponeurosis, which immediately afterwards splits into three layers. The posterior owe passes behind the common origin of the longissimus dorsi m. to the tips of the lumbar spinous processes: it is confounded with the apon. of the ser. post. inf. and latissimus dorsi muscles. The middle one passes between the long, dorsi in. and the quadratus lumbar., and is inserted into the tips of the lumbar transverse processes. The internal, thin and weak, better understood as a continuation of the fascia transversalis, which it so much resembles, passes in front of the quadratus to the transverse processes, and then over the psoae to the bodies of the lumb. vertebrae. Ligamentum arcuatum (Pseud.) The upper part of the fascia transv. post, arching over the quadratus muscle, from the tip of the last rib to the transverse process of the first lumbar vertebra. 132 PERIN^EL FASCIA Lig. arcuat (verum,) the upper part of the same fascia arching over the psose, from the transverse process of the first lumbar vertebra to the body of the second. Both these ligaments afford attachments to the diaphragm, on the under surface of which the fascia trans, post, is continued. Fascia transversalis (anterior.) Hardly perceptible at the umbilicus, it increases in density as it descends, and at the inguinal region appears as a dense shining membrane intimately adherent to the fibres of the muscle (it is a muscular fascia.) Behind the pubis, and, at Poupart's ligament, external to the femoral vessels, it joins the pelvic fascia; where it meets the vessels, it joins the superficial division of the fascia lata (fascia cribrif.) to form the ant. paries of the crural canal. The spermatic cord derives an invest- ment (fascia prop.) from it, in its passage through the inguinal canal. Pelvic fascia. A fine dense muscular fascia, resem- bling the fascia transversalis, to which it is connected along the base of the sacrum, crista ilii, Poupart's ligament external to the vessels, and at the pubis. It covers the iliacus muscle, as the iliacus fascia, and passes over the psose, beneath the iliac vessels, sending a thin layer in front of these, to descend some way on the obturator m. as the internal obturator fascia, but, at a line extending from the pubis to the spine of the ischium, it is reflected upon the upper surface of the levator ani m., which guides it to the sides of the bladder forming the true lateral ligaments of this vis- cus, vagina, and rectum : behind, it is reflected from the sacrum and coccygeus m. to the rectum ; and be- fore, from the body of the pubis and Wilson's mus- cles, as the true vesicle ligaments, to the neck of the bladder and prostate gland. This portion might be called the inner, or deep perineal fascia. Perineal fascist, 1 , the superficial, is analogous to the superficial fascia in other parts. 2, the perineal. FASCIA LATA. 133 The fascia is continuous in front with that of the scrotum : on each side it is firmly adherent to the ramrof the ischium and pubis ; behind, at a line ex- tending from one tuber ischii to the other, it is also adherent to the middle perineal fascia ; here it is said to terminate (Blandin,) but it may still Joe traced, covering the levator ani, and filling up with a mass of fat, the triangular space on the inside of the tuber ischii, formed by that muscle and the lower part of the obturator internus. The sup er- ficial sphincter ani is developed in it. The posteriorly deep fascia of the perineum, impro- perly called triangular ligament of the urethra, arises from the sub-pubic ligament, rami of the ischium and pubis, tuber ischii, inner edge of the great sacro- sciatic ligament, and coccyx: from these attach- ments it passes inwards to the median line, That part which is before the transverse line is composed of strong transverse fibres ; to this the term triangu- lar ligament is applied. Behind this line, it first ascends on the inner side of the obturator internus as far as the line of reflection of the obturator por- tion of the pelvic fascia, and then turns down on the lower surface of the levator ani m. The triangu- lar space lies between these two portions of fascia. The middle part of the levator ani arises from the line, where the obturator fascia from the pelvic, and that from the middle perineal fascia, are united. The ejaculatores semin., erectores penis, and transver- sales m., superficial perineal nerves and vessels, are enclosed between the perineal fascia and triangular ligament, and the levator ani, coccygei, and Wilson's muscles, between the latter and pelvic fascia. The middle perineal fascia bifurcates at the rami ischii et pubis, to enclose the internal pubic artery. Fluid effused in the anterior perineal sheath before the transverse line, will infiltrate the cellular tissue of the scrotum. 12 134 FASCIA LATA. Fascia lata. A dense, fibrous sheath, enclosing the lower extremity. Numerous septa and sheaths are sent from this fascia to the vessels and muscles of the limb. The most remarkable are 1. The Ext. inter- muscular septum, which extends from the trochanter major to the ext. condyle; its inner edge is attached to the whole length of the linea aspera, and separates the vastus ext. from the short head of the biceps, to both of which it gives attachment. 2. The Int. inter- muscular septum extends from the inter-trochanteric line to the internal condyle. It separates the adduc- tors from the vastus int. The femoral vessels and saphenous nerve are enclosed in a sheath derived from the fascia lata, the upper part of which is the crural canal. The lower part of the sheath is formed by a septum, which is sent down from the fascia to bifur- cate and enclose the vessels ; but, above, the fascia (supposing it to pass inwards) comes in contact with the vessels enclosed in their proper sheath, and at a falciform line (which is produced by the tension of the fascia between Gimbernaut'sligamentjPoupart's liga- ment, and external side of the vessels, ) sends off a fascia (cribriform) in front of the vessels and then re- flects itself outwards and downwards to pass und^r them, in order to join the fascia cribiformis at their inner side ; thus reunited, the fascia passses on to the inner side of the thigh. It now appears that the crural canal is formed by an arrangement of the fascia lata, precisely similar to what takes place in forming any other of its simple sheaths. The fascia transversalis j oins the iliac portion of the pelvic fascia; 1st, along the crista ilii and Poupart's ligament, as far as the outer side of the femoral vessels; i. e., a point midway betweeen the ant. sup. spin, process of the ilium and pubic symphysis ; and 2d, from the outer edge of Gimbernaut's ligament to the pubis ; a trian- gular opening is thus left, its base corresponding to the outer or free edge of Gimbernaut's ligament, its apex t o the middle point above mentioned ; its anterior side, CRURAL FASCIA. 135 being the inner half of Poupart's ligament, its poste- rior, the attachment of the pectineus muscle. The anterior and upper part of the femoral sheath, or the cribriform fascia, is connected by means of the falci- form fold to the fascia transversalis at the anterior transverse half of the triangle, and the posterior part of the sheath to the fascia pelvica, at the posterior transverse half; the femoral vessels, enclosed in a proper sheath, occupy the outer part of this canal, leaving between them and the free edge of Gimber- naut's ligament a space through which the intestine makes its way. This space only extends to the point where the saphena vein passes through the cribriform fascia to join the femoral vein, and, except at the inner side of the vessels, the ext. sheath firmly adheres to the proper sheath. It follows, 1st, that this space is the real crural canal; 2d, the sac cannot descend lower than the termination of the saphena vein ; 3d, the upper portion of the cribriform fascia, being the most yielding, is pushed before the sac, which will, in consequence, turn upwards over the edge of the falx ; 4th, as the falx is connected to Gimbernaut's liga- ment, the division of one will tend to relax both. The fascia lata gives a sheath to the sartorius mus- cle, another common to the three hamstring muscles several to the abductor muscles, a very strong one to the tensor femorism. Superiorly, the anterior portion of the fascia lata is united to Poupart's ligament, &c., as described ; posteriorly, it adheres to the crista ilii, and over the sacrum to the posterior lumbar fascia. Below, the fascia is continued over the knee-joint, forming a fibrous capsule, adherent to the patella and its ligament, the femoral condyles, and muscular ten- dons. It is strengthened on the inner side of the joint by an aponeurosis, derived from the vastus internus. Crural fascia, continuous with the fascia lata. This fascia surrounds the leg; it is particularly strong over the extensor muscle, to which it affords some extent 136 PLANTAE APONEUROSIS. of attachment : a strong septum separates the exten- sors from the peroneal muscles, another is placed be- tween the latter and the posterior muscles. The fas- cia is thus subdivided into three principal sheaths; the posterior one is still further divided by a strong fascia, which passes transversely between the super- ficial and the deep set of muscles and posterior tibi- al vessels. Annular ligaments. At the ankle-joint the fascia is strengthened by transverse fibres ; one set the ant. ann. lig., arises from the ext. part of the calcaneum by a small but dense extremity, and, expanding as it runs inwards, sends a branch to the inner malleolus, and another across the foot to the inner edge of the plantar fascia ; the first gives a sheath to the tendon of the tibalist ant. and common extnsor and a partial one to the exten. pollices. The second branch forms a distinct sheath for each. A second set, int. annular ligament, arises from the internal malicious, and ter- minates, broad, into the inner side of the calcaneum, and plantar fascia. The third set, ext. annular liga- ment, extends from the outer malleolus to the calca- neum. Distinct sheaths are formed for the tendons, vessels and nerves passing behind each malleolus.. The dorsal aponeurosis of the foot covers the dor- sum, uniting with the plantar fascia at the edges of the foot, and terminating at the heads of the metatar- sal bones. The plantar aponeurosis is divisible into three por- tions; the middle commences at the inner tuberosity of the calcaneum, and proceeds, gradually becoming broader, to the heads of the metatarsal bones, where it divides into four branches, each of which nearly en- sheaths the corresponding flexor tendon, and is in- serted into the edges of the dorsal expansion of the first phalanges. This portion sends a septum on each side, which separates the muscles in the middle from those on either edge of the sole of the foot; the inner BRACHIAL FASCIA. 137 portion covers the inner muscles of the foot; it arises from the int. annular ligament; internally, it joins the dorsal aponeurosis, and externally, the internal septum; the outer portion, much stronger, covers the muscles on the outer edge of the foot; it arises from the calcaneum; internally it joins the ext. plantar septum, and externally the dorsal aponeurosis; it is also firmly attached to the base of the fifth metatarsal bone. Numerous septa from the upper surface of the plantar fascia pass between the plantar muscles and tendons to be attached to the tarsal and to the edges of the metatarsal bones. The arm and shoulder also possess aponeurotic in- vestments. The supra spinatus, intra spinatus, and subscapular fossse are converted into osteo-fibrous cases by strong aponeuroses, from which the respec- tive muscles derive attachments. The infra spinatus apon. bifurcates to enclose the deltoid ; the superfi- cial layer joins the brachial fascia, and the deep one is attached to the short head of the biceps. The brachial fascia is firmly attached to the mar- gins of the axilla, and appears also to be connected to the acromion and spine of the scapula. It encloses the arm, and is continuous below with the fascia of the fore-arm; the majority of its fibres are circular. Its most remarkable processes are, 1st, int. inter- muscular septum, which is attached to the posterior lip of the bicipital groove below the teres major, and the inner ridge and condyle of the humerus The ex- ternal septum commences at the anterior lip of the bi- cipital groove, where it is united to the tendon of the deltoid, and is firmly attached to the outer condyloid ridge and condyle. The muscles and vessels on the anterior and posterior part of the arm are thus en- closed by' ( two large distinct sheaths, from which small ones are derived for each muscle or vessel. The bra- chial vessels and median nerve have a single sheath. The apneurosis of the fore-arm is strengthened above 138 PALMAR FASCIA. by the expansion of the biceps tendon; a transverse septum separates the superficial from the deep set of muscles on the anterior part of the arm. A similar septum passes between the superficial and the deep- seated extensor muscles on the back of the arm. The dorsal annular ligament of the wrist is com- posed of thin parallel fibres, which extend from the pisiform bone and palmar fascia to the outer edge of the radius. It forms six distinct sheaths: 1st, one for the tendons of the extens. os. metacarpi pollicis and prima internodii; 2, radial extensors; 3, exten. secundi internodii; 4, exten. communis et exten. in- dicis; 5, ext. min. digiti; 6, exten. carpi ulnaris. The ant. annular lig. is a thick fibrous band which arises from the pisiform and unciform bones, and is inserted into the trapezium and scaphoid bones. Most of the muscles of the thumb and little finger arise from its anterior surface. It presents a partial sheath for the tendons of the flex. carp, rad., and only one for the tendons of the flexor muscles and median nerve. The palmar fascia arises from the ant. annular lig. and tendon of the palmaris longus; it is composed of strong diverging fibres, which are disposed over the muscles and tendons in the middle and edges of the hand, -precisely as the plantar fascia in the foot. Composed of transverse fibres, there is a dorsal fascia, derived from the dorsal annular ligament; it covers the back of the hand. A loose but elastic cel- lular tissue serves the purpose of synovial sheaths for the extensor tendons. 139 CHAPTER VII. THE VASCULAR SYSTEM. UNDER this head are comprised the heart, arteries, and veins, the organs for the circulation of the blood ; and the lymphatics, which absorb the lymph and chyle^ and convey them into the sanguineous circulation. SECTION I. THE HEART is of a flattened conical shape, and placed in an ob- lique direction between the two lungs, where it rests upon the central tendon of the diaphragm. Its base, turned upwards and backwards, lies close to the spine, and its apex nearly touches the fifth and sixth costal cartilages of the left side : its edges are turned to either side. The division of the heart into two auricles and two ventricles is indicated, 1st, by a circular furrow, which surrounds the heart near its base, and separates the auricular from the ventricu- lar portions ; and 2dly, by a vertical furrow, which, after dividing the former portion into two auricles, descends on the anterior and posterior surfaces of the latter portion, meeting at a little to the right of the apex. The anterior surface of the ventricular portion is unequally divided by the anterior portion of the ventrical furrow : the greater part, which is on the right of the furrow, belongs to the right ventricle, the smaller to the left. The inferior surface, which rests upon the diaphragm, is nearly equally divided by the posterior furrow. The right margin of the heart, which also rests on the diaphragm, thus forms a part of the right ventricle ; and the left, thick and round, which is lodged in a hollow in the left lung, forms the greater part of the left. 140 LEFT VENTRICLE. The following parts present themselves from before backwards on the base of the heart; 1, the pulmonary artery and infundibulum, behind which, and at first, partly concealed by them; 2, the arota; 3, the circular furrow ; 4, the two auricles, and their appendages, that of the right being in front, and the left behind. The right ventricle (anterior and inferior) is trian- gular ; its parietes, which are thin in comparison with those of the left, are remarkable internally for their reticulated appearance, which is produced by the intercrossing of the carnese columnse; one set of these, few in number, is attached to the parietes of the ventricle by one end only, and by the other to the chordae tendinese and auriculo ventricular valve ; the second by both ends ; the third, in their whole length, by their sides. The auricular orifice posterior, and to the right side of the base, is elliptical, and provided with an auricu- lar membranous fold (tricusp id valve,) which projects into the ventricle; the valve, although it has even more than three angles, is really mitral, each division cor- responding to the ant. and post, half of the ellipsis. The chordse tendinese arise from the ends of the first set of columns, and from the sides of the ventricle, particularly the septum cordis; as their office is to tense and close the valves, one set is inserted into the under surfaces of the valves, and other sets, coming from opposite sides of the ventricle, cross each other to be inserted into the edge of the opposite valve. The orifice of the pulmonary artery is anterior, and to the left side of the base, and separated from the auricular orifice by a portion of the tricuspid valve: it is guarded by three folds (sigmoid valves,) each of which presents a small nodule (corpus aurantii) in its centre. Left ventricle (posterior and superior) differs from the right; first, it exceeds the latter at the apex, but RIGHT AURICLE. 141 is embraced by it at the base; secondly, it is conical and uniformly convex ; it holds somewhat more than the right (Cruveilhier,) somewhat less (Bouillaud ;) thirdly, some of its columns are bifurcated, and they enter into more complex union with each other: its sides are thicker in the prop, of three to one ; fourthly, the valve is more evidently mitral, and the right half alone separates the auricular from the aortic orifice; the latter has three valves, like those of the pulmo- nary, but the two orifices are so near each other that this half of the mitral valve and the adjoining aortic valve have a common base. The right auricle has three sides, an anterior, poste- rior, and that formed by the septum auric. It has five openings. 1. the auriculo ventricular ; 2, that of the vena cava descendens, which looks downwards and slightly backwards; 3, that of the vena cava inf., which forms a right angle with the trunk to open into the auricle close to the septum aur., through the post, side. It is guarded by a valve (^Eustachian,) which surrounds the anterior half, sometimes two-thirds, of the orifice ; one extremity seems to be continuous with the annulus ovalis, the other is lost in the mar- gin of the orifice; 4, that of the coronary vein; this is placed before the latter, and separated from it by the Eustachian valve ; it is provided by a valve (valvula Thesbesiana ; 5, that of the foramen ovale, or rather the fossa ovalis, bounded above and in front by a semi- circular prominent margm,improperlycalled&7zrawws. A projecting muscular fasciculus, said to be the seat of a tubercle (tuber. Loweri,) separates the openings of the two cavte on the right side ; another, in a verti- cal direction, divides the auricle into its sinus, which comprehends these openings, and its proper auricu- lar portion. The auricular portion presents numer- ous vertical muscular fasciculi (musculi pectinati,) which are crossed by smaller oblique fibres, so as to give the surface a reticulated appearance. The for- 142 STRUCTURE OF HEART. amina (Thebesii) seen in this auricle are small ori- fices of a few areolar spaces. The left auricle differs from the right; 1, it is somewhat less capacious; 2, in shape it is an irre- gular cuboid ; 3, the auriculo ventricular orifice is less in size; 4, it has four venous openings (pulmo- nary) without valves, two opening on the right side and two on the left ; 5, it communicates only by a nar- row orifice with its appendix ; 6, it presents no ves- tige of fossa ovalis, unless, which is sometimes the case, the two auricles still communicate by a narrow oblique canal. Structure of the heart. The basement or skeleton of the heart is formed, 1, by two fibrous zones, which constitute the auriculo ventricular orifices, and send expansions into the mitral and tricuspid valves ; 2, by two arterial zones, which in the same way surround the arterial orifices, and send expansions into the sigmoid valves, and three thin, but strong processes, which fill up the intervals between the three festoons at the base of each artery, and strengthen their at- tachment to the ventricles. These two auriculo ven- tricular orifices are closely united in the same plane, and the aortic orifice, placed in their angle of separa- tion in front, is confounded with them in its posterior half. This point is occupied by a cartilaginous or even osseous arch (os cordis) in some animals. The pulmonary orifice is anterior to, and five or six lines higher than the latter. The muscular portion of the heart arises from these zones. The ventricular fibres are separable into three distinct layers. The middle layer forms a distinct conical tube, open at both ends, for each ventricle ; the ventricular septum is formed by their adossement. The outer layer, common to both ventricles, descends in a spiral direction; those covering the right ventricle to the left, and those on the left ventricle to the right, as far as the apex. The two layers, twisting half INVESTMENTS OF HEART. 143 round each other, now enter the openings at the apex of each tube formed by the middle layer, and divide into two sets to form the inner layer of each ventricle. The first set pass upwards, to line the opposite side of the ventricle, and the second, variously contorted, ascend on the same side ; in both cases those fibres which were superficial in the outer layer become the deep-seated in the inner one. The columnse carnese seem to be made up of portions of the first, and of spiral fibres of the second set. Auricular fibres. A common layer extends trans- versely across the anterior surfaces of both auricles. Of the layer proper to each auricle, a circular set of fibres is seen near the auriculo ventricular openings, and a second set, running an oblique course, is ar- ranged in arches, which are fixed by their ends to the ventricular zones, their free portions surrounding the venous orifices, and projecting between them. The annulus ovalis is formed by some muscular arches of the septum. If the common ventricular fibres be cau- tiously cut through at the vertical furrow, the ventri- cular tubes may be separated from each other entire. Development. At an early period of conception, the heart fills the thoracic cavity, and, up to three months, its direction is vertical, and its shape round and symmetrical. The ventricles are very minute, and the right auricle in size equals the rest of the organ; subsequently its four cavities are nearly equal. The auricular septum is wanting, and the ventricu- lar is deficient at its upper part ; the auricles after- wards communicate by the foramen ovale, and the ventricles indirectly by the ductus artenosus. The Eustachian valve covers part of the orifice of the sup. cava, as well as that of the lower one (Martin St. Ange;) as development proceeds, the foramen ovale is gradually closed by a membrane, and the Eustachian valve diminishes in the same proportion. The heart is enclosed in two distinct investments, 144 ARTERIES OF HEART. 1. The fibrous pericardium. This membrane ia formed of aponeurotic fibres ; it is conical in shape, its base corresponding to the tendon of the dia- phragm, to which it adheres in the adult; its apex surrounds the origins of the large vessels, upon which it is gradually lost. Its size is said to equal that of the heart in the greatest state of distention. 2. The serous pericardium. A complete sac of se- rous membrane which lines the former envelope, and is reflected from it on the great vessels and heart ; it passes up on the former to some distance, especially on the aorta and pulmonary art., least on the inf. vena cava. The endocardium (Bouillaud) is a white pellucid membrane, resembling the arachnoid; it lines the cavities of the heart, covers the valves and tendinous cords, and is continuous with the inner coat of the arteries. In the neighborhood of the zones and in some of the areolse of the auricles, it comes into con- tact with the serous pericardium. The valves of the heart are formed by folds of this membrane, with a little fibrous tissue at their free margins. The aortic and pulmonary valves are named semilunar and present each, in the centre of its free margin, a slight eminence, the corpus aurantii. The heart is supplied with blood by the coronary arteries. These arise from the aorta, immediately above its opening and behind the aortic valves; the right supplies the right auricle, the posterior part of the ventricles, and the thin edge of the heart; it sinks into the right auriculo ventricular groove, winds round to the back of the heart, sends a long branch along the anterior thin edge of the heart, runs along the groove on the posterior surface,'and terminates by in- osculating with the left; this supplies the left auricle, left ventricle, and septum. One branch runs in the left auriculo ventricular groove, the others along the anterior surface of the heart, opposite the septum and THE AORTA. 145 terminates near its apex by inosculating with the right. The coronary veins terminate by one large opening in the right auricle, between the Eustachian valve and auriculo-ventricular opening. A few veins open directly by small apertures into the right auri- cle. The heart is supplied with nerves from the cardiac plexus. This is formed by branches from the sympa- thetic, the par vagum, and recurrent nerves. It gives off the coronary plexuses to accompany the arteries, and terminates in the muscular tissues of the heart. SECTION II. THE ARTERIES. PULMONARY ARTERY, Or. from the circulus arteri- osus of the right ventricle, which at this point dilates into a kind of infundibulum. At first in front of the aorta, between the two auricles, it crosses to its left side, and divides into its two pulmonary branches; the right, an inch and a half long, passes under the arch of the aorta, behind the descending cava, and in front of the bronchus ; and the Ireft, an inch long, in front of its descending portion and left bronchus, and behind the pulmonary veins. It is attached to the heart, 1st, by its inner tunic; and 2dly, by pro- longations from the arterial zones, which are attached to the- convex edges of its three festoons, and/ to the edges of their angular intervals. The fibrous peri- cardium covers the greater part of its two branches. AORTA, Or. in the same manner as the pulmonary artery, immediately behind that vessel, in the anterior triangular interval formed by the ventricular zones. The arch commences from this point, which is oppo- site to the upper edge of the fourth costal cartilage of the left side, where it joins the sternum, and coming forwards ascends to the upper edge of the second cos- tal cartilage on the right side; 2, it passes horizon- 13 146 CORONARY ARTERIES. tally backwards on a level with the junction of the first with the second bone of'the sternum to the left side of the body of the second dorsal vertebra; 3, it lastly descends, still inclining backwards, to the same side of the third or fourth dorsal vertebra, under the name of thoracic aorta, continues this course, coming more and more in front of the spine, enters the abdo- men through the aortic opening of the diaphragm, and, finally, as the abdominal aorta, it passes to the body of the fourth lumbar vertebra, where it divides into the two common iliac and middle sacral arteries. Relations of the arch. Within the pericardium, which reaches its transverse portion, the artery is, first, immediately behind the infundibulum of the right ventricle, and the pulmonary artery ; it then gets to the right side of this vessel, and to the left of the vena cava descendens. Its transverse and de- scending portions form an arch over the root of the left lung ; its transverse portion is partially covered by the left vena innonjinata; it rests on the bilfur- cation of the trachea posteriorly. The phrenic and vagus nerves descend on each side, the left vagus a little in front of it. Its recurrent branch hooking round it where it is joined by the ductus arteriosyis. The primary Branches of the Aorta. From the arch; 1, 2, coronary arteries, 3, A. inno- minata, 4, left common carotid, 5, left subclavian. From the Thoracic portion ; 6, intercostales, 7, Bron- chiales, 8, cesophageal, 9, mediastinal. From its abdominal portion ; 10, Phrenicse, 11, cod- iac, 12, sup. mesenteric, 13, inf. mesenteric, 14, capsula- ares, 15, renales, 16, spermatic, 17, lumbar, 18, common iliac, 19, sacram.edia. Art. Coronaria have just been described. 1st set from the convexity of the arch. LEFT COMMON CAROTID. 147 ART. INNOMINATA, from an inch to an inch and a half in length, arises from the summit of the arch, passes upwards, for- wards, and to the right side, and divides opposite the right sterno-clavicular artic. into the right com.carot. and the subclavian trunks. Red, behind, the trachea and right pleura, before right vena innom., sterno- hyoid and thyroid m. upper bone of the sternum. RIGHT COMMON CAROTID. ' This art. passes from its origin upwards, forwards, and a little outwards in the neck, along the inner edge of the sterno-mastoid nerve, until it arrives at the upper border of the thyroid cartilage, and di- vides into its terminal branches, the ext. and int. carotid arteries. In its first stage it lies in the ant. inf. triangle of the neck ; it is here covered by the skin, platysma, and partially by the sterno-mastoid externally, the sterno-hyoid and thyroid internally ; it is enclosed in the carotid sheath, lying internally to the vagus nerve and int. jug. vein, behind it are the sympathetic and recurrent nerves. In its second stage this art. lies in the ant. sup. triangle of the neck, and is covered only by the skin, platy- sma, and fascia ; its other relations are similar to those in the first stage. LEFT COMMON CAROTID. Arises from the arch of the aorta within the thorax, it is here covered by the left vena innom. and the origins of the sterno-hyoid and thyroid muscles, to its inner side is the trachea, to its outer the left sub- clavian and cone of the pleura, behind it is the tho- racic ducfand oesophagus. In the neck it is similar in course and relations to the right com. carotid, with the exception of its connection with the oeso- phagus and thoracic duct. The right and left com. carotids differ in their ori- 148 FACIAL ARTERY. gin, length, and a few of their relations, as just de- scribed. The terminating branches of the com. caro- tid art. are the external and internal carotid arteries. EXT. CAROTID. Ascends inwards and forwards to the submaxillary gland; then backwards, imbedded in the parotid gland, parallel to and behind the ramus of the jaw, as high as the neck of the condyle. Rel. ext. integuments and platysma ; the digastric and stylo-hyoid m. and ninth nerve ; the seventh nerve, int. the stylo-glossusandpharyngeus m. which sepa- rate it from the int. carotid Ram. 10 in no. Anterior Set. Thyroid superior, Or. opposite the cornu of the os hyoides. It runs below this cornu, and the lingual nerve, and upon the sup. laryngeal nerve. Ram. 1, hyiodeus, cellular membrane between the stylo- hyoid muscle; 2, superficiales, sheath of the carot., glands, and sterno-mastoid muscle ; 3, laryngeus, larynx, epiglottis; a branch descends on the crico- thyr. memb. ; 4, thyroideus, generally three, to the thyroid gland. Lingualis, runs, 1st, horizontally above the cornu of the os hyoides; 2d, vertically, to the base of the tongue; and 3d, horizontally, as the Ranine artery, to its tip. Ram. 4. 1, hyoideus supra hyoid muscles, epiglottidean glands; 2, dorsalis linguse, dorsum of the tongue, tonsil, pal. arches, &c. ; 3, sublingualis, sublingual gland, mucous membrane; 4, Ranine, along the outer side of the genio gloss, m. to the tip of the tongue. Facialis, upwards and inwards to the submax. gland, forwards on the upper edge of the gland, and upwards from the ant, edge of the masseter to the labial commissure, alanasiand inner canthus of the orbit. Ram. 6. 1, Inf palatine, ascends between the stylo gloss, and pharyngeus to the sup. constrictor tonsil, velum, &c. 2, Tonsillaris, between the stylo INTERNAL MAXILLARY GLANDS. 149 gloss, and int. pteryg. m. to the tonsil ; 3. Glandu- lares, to submaxillary gland; 4, Submentalis runs close under the jaw, to the muscles at the symphysis menti; 5, abialis. inferior, lower lip and chin; 6, Coron. inferior, mucous membrane of the lower lip and labial glands; 7, Masseteric, masseter, buccina- tor; 8, coronaria sup., mucous membrane of the upper lip and labial glands; 9, nasi later alis, side of the nose in numerous anastomoses ; 10, angularis lacrymal sac, orbicularis muscle. Posterior Set. Sterno-mastoid, to that, and to the adjoining mus- cles and glands. Occipitttlis, ascends parallel to, and concealed by, the post, belly of the digastric ; passes between the transverse process of the atlas and mastoid process ; and then upon the recti beneath the other cervical muscles which it lastly perforates at the centre of the sup. transverse ridge. Ram. 1 , mastoid; 2, post meningeal; 3, cervicalis descendens, which de- scends between the splenius and complexus; 4, parietal, parietal foramen; and 5, terminal, upon the back of the cranium. Posterior auris, Ram, auricular, muscular, parotides, and stylo -mastoid, which passes through the Fallopian canal, to the tympanum and labyrinth. Inner Set of Branches. Pharyngea Ascendens ascends deeply by the side of the pharynx ; Ram. pharyngeal, to the pharynx, tonsils, and palatine arches, post, meningeal, through the post, foramen lacerum; ant. meningeal, ant. fora- men lacerum ; Eustachian, to that tube, and to the tympanum. Terminal Set of Branches. Trans, faciei, runs a little below the zygoma to an- astomose on the face with the other facial branches. Internal maxillary passes 1, inwards behind the 18* 150 OPTIIALMIC ARTERY. neck of the jaw ; 2, upwards and inwards, in a space bounded by the two ptcrygoidei m., the buccinator and the ramus of the jaw ; 3, horizontally, forwards between the heads of the pteryg. ext. across the pteryg. maxillary fossa to the infra orbitar canal Ram. first part of its course; 1, Art. meningea media magnet, through the foramen spinale ; ramus hiatus Fallopii to the facial nerve; 2, Infra dental, Ram. mylo-hyoid, to that muscle, and labial glands. Second Order. 3, Deep temporal, two to the deep surface of them, 4, Massetericse ; 5, Pterygoidei; 6, Buccales ; 7, Supra dental, roots of the post, teeth, and antrum. Third Order; 8, Infra orbitar (terminal) antrum, ant. alveoli, and face ; 9, palatina descendens, pos. palatine canal, palate, ram. incisivus ; 10, Nasalis, spheno-palatine foramen, and nose, ram. nerve. Cotunnius; 11, videan, pterygoid foramen, to accompany the nerve. Temporalis ; Ram. 1, auricular, capsule of the jaw; 2, Terminal, temporaries, anterior, media et posterior. INT. CAROTID, runs upwards, vertically, to the foramen caroticum, forwards along the canal, tor- tuous, through the cavernous sinus, vertically, by the side of the anterior clinoid processes. Rel. Int. side of the pharynx, tonsil, symph. nerve; ext. pneumogastric glossopharyngeal, and ninth nerves; int. jugular vein; post. vert, column; ant. stylo gloss, et. pharyngeus m. Internal to all the nerves in the cavernous sinus. Ram. A, Opthalmic passes with the nerve through the foramen opticum. In its passage through the orbit it lies 1, on the outside of the nerve, 2, on its upper part, 3, on its inside. Ram. first part of its course; 1, Lacrymal to the gland, palpebra, some pierce the os mala ; 2, Centralis Retina, centre of the optic nerve POSTERIOR CEREBRAL ARTERY. 151 and vitreous humour, to the posterior surface of the lenticular capsule. Second Part of its Course. 3, Supra orbatilis, through the supra orbitar notch to the forehead ; 4, ciliary posterior, 15 to 20, through the sclerotic coat, to the choroid coat, ciliary pro- cesses, and to the larger circle of the iris; 5, ciliary long, two in no., anas, in circles on the post, surface, and smaller circle of the iris; 6, muscular, superior and inf. Ram. ciliary anterior, to the larger circle of the iris, arid conjunctiva. Third Part of the Opthal. Art. 7, Ethmoidal posterior ; through the post. For. Eth. to the dura mater, and nasal fossae; 8, Ethmoidal anterior; ant. For. Eth. to the frontal sinus, nares; 9, Palpebral, superior et inferior. Termination of the Opth. Art. 10, Nasal, anastom. with the term, branch of the facial; 11, Frontal, to the inner part of the forehead. Art. communicans post. (Willis) runs backwards, along the outer side of the pituitary gland and corp. mamil., to join the post, cerebral artery, which is a branch of the Basilar. Choroid, backds. and outds. along the optic 'fascic., enters the lat. vent, through the great fissure, and is lost in the choroid plexus. Ant. cerebral, anastomoses with its fellow, by means of the art. communicans ant. and then runs, from before backwards, on the upper surface of the corpus callosum ; supplies the hemispheres. Middle cerebral, in the fissure of Sylvius, to the ant. and .middle lobes. Cereb. Branches from the Art. Basil. Post Cerebral, to the Thalami, Tuberc. Quadri- 152 SUBCLAVIAN ARTERY. gemina. etc. It is joined by tlie cornmunicans of Willis. Ant. Ccrebellar super, surface of the cerebellum. Ram. Int. auditory, through the int. meatus to the internal ear. Post. Cerebellar, sometimes arises from the verte- bral: passes between the origins of the ninth pair of nerves, and just in front of those of the eighth, to the post, part of the cerebellum. SUBCLAVIAN ARTERY extends from its origin to the lower edge of the first rib ; it runs, 1st, upwards and outwards to the scaleni; 2d, horizontally between them; 3d, down- wards and outwards to its termination, Rel. before it reaches the scaleni. The Right, 1, Ant. sterno. clavic. artic. ; parallel to the subclavian vein where it joins the jugular; 2, crossed by the phrenic and vagus nerves ; 3, post. recurrent nerve ; pleura : surrounded by filaments of the sympathetic nerve. The Left, differs, 1, Ant. its crossed by the subc. vein; 2, the phrenic and vagus are parallel to it; 3, it is nearer the clavicle than the spinal column; 4, in more extensive contact with the cone of the pleura and lung. The thoracic duct ascends between it and the left carotid, it is larger than the right, and is more deeply seated in its first course. In the root of the neck, before passing behind the scalenus antic, muscle, the subclav. art. are covered by the skin, platysma,sterno-mastoid and sterno-hyoid muscles and cervical fascia ; this is the first stage. Second Part. Between the. scaleni ; the brachial plexus above and posterior, and the first rib below, the cone of the pleura behind ; the ant. scalenus sepa- rates it from the vein. Third Part. Lies in the pos- terior inf. triangle of the neck covered by the skin, t THYROID ARTERY. 153 platysma, and a quantity of loose cellular tissue, the ext. jug. vein descends in front of it, and its own vein lies ant. and inf. to it ; the brachial plexus lies above and behind, and the first rib immediately pos- terior to it. Ram. First Part of its Course. Art. vertebral, (always the first branch,) runs through the transverse foramina of the cervical ver- tebras, from the sixth (sometimes fourth) to the se- cond, passes- outwards to reach that of the first, and winds horizontally backwards, in a groove behind its artic. process; pierces the post, occip. atloidean lig. beneath the suboccipital nerve, and, proceeding forwards and upwards through the foramen magnum, inclines to its fellow on the ant. surface of the medul. oblongata. It lastly, unites with it at the pons to form the Art. Basilaris. Ram. 1 and 2, anterior and posterior Medulla spinalis. 3, Basilar art., extends the whole length of the pons Varolii. Internal mammary arises opposite the last, descends in the thorax behind the costal cartilages, close to the sternum, to the xiphoid cartilage. Rel., crossed by the phrenic nerve which then lies on its inner side. Ram. 1, ant. intercostal, 5, to the five superior inter- costal spaces ; 2, mediastinal, thyrnicce, glandulares, muscular, &c.; 3, Comes, nervi phrenicse, runs with the nerve to the diaphragm. It terminates in 4, musculo-phrenicse, diaphragm and inf. intercostal spaces; 5, abdominales, anas, with the epigastric and lumbar art. Thyroid, an axis of three branches; 1, Thyroid inf. or ascendens, ascends behind the carotid sheath to the thyroid gland; 2, cervicalis ascendens, ascends on the ant. scalenus, parallel to the phrenic nerve ; 3, supra scapularis, or transversalis humeri, to the su- pra scapular notch. Ram. supra acroniial, supra spinalis, and infra spinalis. 154 THORACICA STJPREMA ARTERY. . Transversalis colli, across the neck above the trans, humeri. Ram. 1, cervical super/, to the fascia, lym- phatic glands, &c. 2, scapularis post, (terminal) post, angle, crista and inf. angle of the scapula. Second Part of the Subclav. Art. Cervicalis profunda, passes between the 6 and 7 cervical transverse processes, and ascends deeply in the spinal groove ; anas, with the occipital and ver- tebral art. Inter costalis sup. descends on the outer side of the first thoracic ganglion; Ram. 2, one to the first, and one to the second intercostal space. AXILLARY ARTERY Extends from the infer, edge of the first rib to the lower margin of the latissiinus dorsi and teres mus- cles; it is divided into three stages by the pectoralis minor, which crosses in front, of it. Rel. Ant. Pect. major above and below; pectoralis minor in middle post, a cellular space, then teres major and latissimus dorsi m.; Ext. coracoid process, subscapularis m. and head of the humerus: int. first intercostal space-, skin of the axilla. The vein, first at some distance on its inner side, gets nearer and more anterior to it in descending. The brachial plexus, first on its outer side, gradually embraces it; the inner root of the median, the int. cut an. and ulna nerves, are given off on its inner side; the ext. cutan. and outer root of the median on its inner side; the nmsculo spiral, and circumflex nerves, behind it. Ram. At the upper edge of the pectoralis minor. Thoracica acromialis (constant. ) Ram. Pectorales acromialis, deltoidean ; a branch separates the del- toid from the pectoralis major m. Thoracica suprema (irregular,) ramifiesbetween the pectoral muscles ; anas, with the int. mammary art. SUPERIOR PROFUNDA ARTERY. 155 Thoracica alaris (irreg.) to the eel. tissue and glands in the axilla. Below the pect. minor. Thoracica longa (const.) descends parallel, and close to the lower edge of the pector. minor m., be- tween the p. major and serratus magnus, to the side of the thorax. Subscapularis runs along the lower edge of the sub- scapular m. accompanied by the subscap. nerve, to the inf. angula of the scapula. Ram. 1, Dorsalis scapulse, through the triangular opening formed by the long head of the triceps, teres major, and edge of the scapula, to the subscapular fossa. Post, circumflex *) encircle the surgical neck of the Ant. circumflex jhumerus. Ram. 1, Deltoidean; 2, artic. which ascends in the bicipital groove. BRAOHIAL ARTERY. Extends from the termination of the preceding to the bend of the arm, in a line from the centre of the axilla to the middle of the latter; Rel. 1, in the arm: Ant. inner edge of the coraco brachialis and biceps, which overlap it ; Post, triceps, brachialis anticus and musculo spiral nerve. Int. ulner nerve and inf. pro- fund, art. Ext. coraco brachialis, cellular interval between the brachialis antic, and biceps. The median nerve, first on its outer side, crosses at about its mid- dle to lie on its inner side; 2, Rel. at the elbow ; Ant. expansion of the biceps, skin, basilic vein, Post, mid- dle of the brachialis anticus, Int. median nerve, Ext. tendon of the biceps, Ram. Prof unda Sup. descends in the spiral groove round the posterior surface of the huinerus to anas, with the radical recurrent in the groove between the brachialis antic, and supinator longus, Ram. 1, descends to the inner part of the elbow-joint; 2, to accompany the deep branch of the spiral nerve ; 3, musculares. 156 RADIAL ARTERY. Profunda Ins. descends on the inner side of the arm along with the ulnar nerve to anas, with the post, ulnar recurrent, between the int. condyle and olecranon process. Ram. musculares. Anastomotica Magna, anas, super, with the inf. pro- funda, and inf., with the ant. and post, ulnar re- current. Art. Nutritia humeri; i. e. Terminal, Radial, and Ulnar arteries. The brachial art. is superficial throughout, being covered only by the skin and fascia, and in the centre by the inner edge of the biceps, nervous filaments from the int. cut. and nerves of Wrisberg He over it; it is accompanied by the brachial vein which lies to its inner side. Below the bend of the elbow it sinks into a triangular fossa, bounded by the brach. antic, above, the pronator teres internally, and the supinator longus externally, and divides opposite the coronoid process of the ulna into its terminal branches, the Radial and Ulnar arteries. RADIAL ARTERY Extends from the elbow to the wrist, in a line from the middle of the elbow-joint to the root of the thumb. Rel. Ext. Supinat. Rad. Long.; and for some distance the radial nerve. Int. Pronator teres, and flexor carpi radialis. Post, attachments of the supin. brevis and pron. teres ; flexor long. poll. ; and ant. surface of the radius. Ant. above supin. long., below fascia and skin. Ram. 1, Recurrent, anas, with the sup. Profunda; 2, Superficialis Volse, runs over the annu- lar lig. through the short muscles of the thumb to join and complete the superficial palmar arch; 3, Ant. Carpi Radialis. The vessel now passes backwards beneath the two first extensors of the thumb to the first interosseous space, which it traverses above, or through the fibres of the abductor indicis m. Here it may be felt in a space bounded by the two first extensor tendons of the ULNAR ARTERY. 157 thumb, and that of the third, Ram. at this stage. 4, Dorsalis carpi, Rad. carpus and wrist-joint; 5, and 6, Dorsalis Pollicis, dorsal edges of the thumb ; 7, Pr-in- ceps vel magna pollicis, runs between the abd. indicis and abd. pollicis, divides at the first phalanx of the thumb into its two margin branches ; 8, Radialis Indicis, anas, with the superf. palmar arch, and be- come a digital artery. The terminal branch, or Pal- mar is prof unda, crosses the carpal heads of the meta- carpal bones, covered by all the soft parts, and on that of the little finger joins the Ram. communic. of the ulnar art. and thus forms the deep palmar arch. The Ram. of this arch are five in number. They supply the inter ossei, and at the cleft of the fingers, join the branches of the superficial arch before they bifurcate. ULNAE, ARTERY Descends, with a curve towards the inner side of the arm, from the elbow to the inner side of the pisi- form bone. Rel. at the upper third of the arm it lies between the two layers of flexor muscles ; it after- wards rests, with the ulnar nerve on its outside, on the flexor profundus. At the middle third of the arm it is covered by the adjoining edges of the flexor sublim., and flex, carpi ulnaris; at the lower third by the skin, and fascia : Ram. 1 2, art recurrent, ant. et post, anas., the first with the anastomotica magna and the inf. protunda ; the second with the former vessel and the sup. pro- funda; 3, interossea, runs downwards and backwards to the interosseous space, where it gives off" two recur- rent branches, and the ram. interos. post. ; it then de- scends on the ant. surface of the ligament, and at the upper edge of the pronator quadratus divides into ant. and post, carpal branches, the former anas, with the deep palmar arch, and the latter with the ram. dorsa- lis carpi. The ram. interos. post. perf. the upper part of the lig., gives off a post, interos. recurrent, and 14 158 BRONCHIAL ARTERIES. descends as far as the dorsum of the carpus. The recurrent branches anas, with branches of the radial art. ; 4, descend. muscul. vel nervi mediant to the super- ficial flexors ; 5, 6, r. carpi ulnaris, ant. and post. The ulnar artery now passes from the inner side of the pisiform bone, over the annular lir*., gives off the communicans profund. to complete the deep pal- mar arch, and then as the r.palmaris super/, it arches across the hand, beneath the palmar fascia and skin, and, between the ball of the thumb and index finger, joins the superf. volae and rad. indicis, to form the super/, palmar arch. Four digital branches are given off, each of which first anas, with a branch from the deep arch, and then divides into two collateral branches; they supply the edges of the three last fingers and the ulnar side of the index. The digital vessels and nerves run along the late- ral surfaces of each finger, and nearer its anterior surface; they terminate in a free anastomosis in the expanded extremities of the fingers, and endow these with common sensibility, and the special sense of touch. THE THORACIC AORTA is situated in the post, mediastinum,' and extends from the left side of the fourth dorsal vertebra to the aortic opening of the diaphragm. Rel. ant. the left pleura, root of the left lung, oesophagus, the left au- ricle of the heart, and pericardium, post, left side, and afterwards the fore part of the spinal column: owing to this inclination, the oesophagus and vagi, which above are placed on its right side, cross it to lie, below, rather to its left side; behind it, also, are the left intercostal veins, going to join the azygos. The splanchnic nerves lie on each side of it, and the tho- racic duct and azygos vein on its right side. Ram. Bronchials, generally four in number, two on each side ; their branches twine around the bronchi to sup- ply the substance of the lung; anas, with the pulmo- (XELIAC AXIS. 159 nary artery (Ruysch, Cowper, Waller,) with the pul- monary veins (Harrison.) (Esophageal, from one to four or five to the oesopha- gus; they anas, with other art. by ascending and de- scending branches. Inter co stales, from eight to ten on each side, they run in the eight or ten inf. intercostal spaces, and anas, with the int. mammary a. Each gives off a ram. postic., which passes between the spine and costo- transverse lig. to supply the cord, and deep dorsal muscles. THE ABDOMINAL AORTA descends, inclining slightly to the left side, from the diaphragmatic opening to the body of the fourth or fifth lumbar vertebra. Rel. ant. lesser omentum, sto- mach, solar plexus, vena porta, mesenteric vessels, pancreas and duodenum, transverse mesocolon, root of the mesentery, and small intestines. Right side, vena cava, thoracic duct ; both these vessels are be- hind it at their origins. On each side lies the sym- pathetic nerve. Post, the pillar of the diaphragm and lumbar vertebrae. Ram. Diaphragmatic, right and left, they encircle the di- aphragm, and join at its ant. edge; anas., with lower intercost. arts. CCELIAC AXIS, a short trunk projecting horizontally from the aorta immediately below its diaphragmatic opening. Rel. the pancreas and vena porta below it; the lob. Spigelii on its right; the renal capsules and semilunar ganglions on each side; enveloped by the solar plexus and covered by the stomach. It is an axis of three branches. a, Gastric or coronar. ventriculi, runs to the cardiac orifice of the stomach, and divides into, 1, ram. super. to the oesophagus, and larger end of the stomach; 2, ram. infer, follows the lesser curvature, anas, with the sup. pyloric art. of the hepatic. 160 SUPERIOR MESENTERIC ARTERY. HEPATIC, runs enclosed within the smaller omen- turn, 1st, transversely towards the pylorus, and 2dly, upwards and forwards to the transverse fissure of the liver. Ram. 1st stage, 1, sup. pyloric, to the pylorus, anas, infer, branch of the gastric ; 2, gastro-duode- nalis, accompanies the ductus communis choledochus, and between the duodenum and pancreas, divides into pancreatico duodenalis, and gastro-ejnploica dextra. The former supplies the corresponding organs, the latter runs along the larger curvature of the stomach, and anas, with the gastro-epiploica sinist., a branch of the splenic. Terminal Branches. 3, Hepatica sinistra, left lobe of the liver ; 4, hepatica dextra, to the right lobe; from this is derived the ram. cystica to the gall bladder. SPLENIC, five or six inches long; it runs with the vein to the left side, along the upper and post, part of the pancreas, and terminates by five or six br. in the spleen. Ham. 1, pancreatic 'se parvse, ramusculi to the gland ; 2, pancreatica magna, runs from left to right along with the duct; 3,vasabrevia; five or six large, but short, branches arising from the trunk, or its splenic divisions, to ramify in numerous anas, on the larger end of the stomach ; 4, splenicse, five or six in number, to the spleen; 5, gastro-epiploica sinistra, runs from left to right on the larger curvature of the stomach to anas, with the right corresponding ves- sels from the hepatic. SUPERIOR MESENTERIC, arises from the aorta at the lower edge of the pancreas, which separates it from the coeliac, and above the transverse portion of the duodenum. It descends, forming a slight curve, to the right iliac fossa. Ram. 1st, from its convexity. a, Mesentericse,MteQn or twenty branches, they anas. with each other in a series of arches, which become smaller and more numerous as they approach the small intestines, to which they are finally distributed. RENAL ARTERIES. 161 2d, from its Concavity. b, Colica media, to the transverse colon, anas, on the left, with the colica sinist., on the right with the colica dextra. c, Colica dextra, to the ascending colon, anas, above with the colica media, below with the ilio colic. d, Ilio colic, to the caecum, valve, &c., anas, above with the colica dextra, below with branches from the inferior mesenteric art. INFERIOR MESENTERIC, arises about an inch above the bifurcation of the aorta, and descends towards the left iliac fossa. Ram. a, Colica sinistra, to the descending colon, anas. above with the colica media, below with the art. sigmoidea. b, Art. sigmoidea, to the sigmoid flexure, anas. above with colica sinistra, ram. to the psoas, iliacus m. and ureter. c, Hsemorrhoidalis superior, descends in the meso- rectum to the rectum, and at about its middle divides into two branches, which descend on the sides of the organ, some of their ramusculi even reaching the anus; anas, with the middle and inf. hsemorr. art. All the foregoing branches of the abd. aorta are accompanied each by a plexus of nerves, named after each vessel, and derived from the semilunar gang- lion, solar plexus, and sympathetic nerve. Their blood is returned by the vena porta, which passes through the liver before pouring its blood into the inf. vena cava. Copsulares, large in the foetus, supply the supra- renal capsules. RENALES, arise between the two mesenteric arte- ries, the right, which is the longer, passing behind the vena cava. Their branches, four or five in num- ber, run between the mammillae of the kidney, anas. 14* 162 COMMON ILIAC ARTERIES. in arches, and then terminate in its cortical sub- stances. Some branches reach the capsule. Spermaticse arise immediately below the former, the right frequently from the right renal. They de- scend, crossing the psose m. and ureter on each side, and at the inner ring join the vas deferentia, which guide them to the testicles. In the female they run to the ovaria. Ram. in the male, a, ram. to the psose, ureter, and adjoining tissue; b, six or seven to the epididymis and body of the testis. In the female, a, ram. to the ovaries, especially to the uterus, where they anas, with the uterine arte- ries; b, ram. accompany the round lig. Lumbales, five in number, corresponding to the vertebral spaces. They divide into, a, ram. spinales to the cord, and through anutr. foramen to the body of each lumbar vertebra ; b, post, muscular; c, circu- lar or abdominal, analogous in their course to the in- tercostales with which they anastomose. Terminal Branches of the Aorta. Sacra media (caudal artery of animals) descends on the sacrum and coccyx ; it supplies the rectum, and anas, at each division of the above bones with the lateral, sacral, and hsemorrhoidal arteries. The abd. aorta at its bifurcation lies in front of, and a little to the left side of, the fourth lumbar ver- tebra ; it is here nearly opposite the umbilicus, and has the vena cava to its right side, the sympathetic on either side ; it bifurcates into the ILIACJB COMMUNES extend from the fourth lumbar vertebra to the sacro iliac artic. Rel. crossed by the ureters and spermatic vessels, resting above upon the^bodyof the last lumbar vertebra, below against the inner edge of the psoasm. The two corresponding veins lie beneath and on their OBTURATOR ARTERY. 163 inner sides, and the left in j oining the right to form the vena cava ascend. , passes beneath the right iliac artery. Ram. to the psooe, ureters, &c., they sometimes give off the sacra media, and last lumbar arteries, and even therenales, and spermaticse (Cruveilhier;) b, ram. terminal, iliacse extern et intern. INTERNAL ILIAC, About an inch and a half long, descends vertically (bending slightly forwards) from the sacro iliac joint to the upper edge of the sacro sciatic notch. Many of its branches sometimes arise from a common trunk. Anterior Set of Branches. a. Umbilical, large in foetal life, they soon dwin- dle after birth into fibrous cords, which may be traced along the sides of the bladder to the umbili- cus ; near their origins, where they still remain per- vious, some of the principal vesical branches arise. b. Vesicates, four or five, derived principally from the umbilical, and from the middle hsemorr. obtur- ator, vaginal, and uterine arteries. Earn., 1, infer. vesic. semin., prostate gland, and neck of the bladder; 2, media, along the uterus to the sides of the blad- der; 3, super., ant. surface of the bladder. c. Obturator, may arise from the femoral or epi- gastric art., when it winds round the infer., or the super, and inner margins, of the femoral ring. It runs parallel to, but below, the ext. iliac vessels, accompanied by its nerve (which is above it,) to the obturator foramen. Ram. 1, a cross branch, by which it joins its fellow behind the pubis; 2, vesicalesmuscu- lares, iliacseto anas, with the circumflexa ilia. Having traversed the obturator foramen, its branches are, 1, Ram. intern, runs round the inner half of the ob- turator foramen, between the two obt. m., which it supplies, and anas, with the ram. extern. ; a branch descends between the two first adductor m. 2, ram 164 ISCHIATIC ARTERY. extern, between the obt. m. round the ext. half of the foramen, anas, between the neck of the femur and quadratus muscle with the ischiatic art. ; a branch enters the joint through the notch; other br. supply the muscles. Int. Branches. d. Middle hsemorrhoidal, to the ant. part of the rectum, anas., above and below, with the other haemorrh. branches. e. Uterine, runs in the broad lig. to the neck of the uterus, on w T hich it ascends to anas, with the spermatic art. f. Vaginales, surround the vagina. Posterior Branches. g. Heo-lumbar, divides behind thepsoas. m. into, I, ram. ascend., anas, with the last lumbar art.; 2, transversales, superficial and deep, to the iliacus m.; 8, the nutritious art. h. Sacra lateralis, descends in front of the sacral foramina. Ram. to the spinal cord, and to the mus- cles on the back of the sacrum; anas, with the sacra media. i. GLUTEAL, escapes between the upper edge of the sciatic notch and pyriformism., and immediately divides into, 1, ram. super/., runs between the g. max. et medius m. ; 2, r. profund., between the g. medius and minim. ; it sends a branch along the g. min. to the spin. p. of the ilium, a second across this m. to the g. medius, a third through the g. min. to the artic. capsule. Inf. Branches. k. ISCHIATIC, escapes from the pelvis, between the lower edge of the pyrif. and sciatic lig. Ram. to the gluteus max., lev. ani, and coccygeus m. ; 2, comes nervi ischiatici. CAVERNOUS ARTERIES. 165 1. INTERN. PUDIC, descends upon the pyriforrnis m., internal to the former vessel, with which it escapes from the pelvis ; 2, it winds over the spine of the ischium, beneath the larger sciat. lig., and enters the smaller sciatic notch; 3, it ascends on the inner side of the tuber ischii and rami ischii et rubis, but not within the pelvis, to the arch of the pubes, cov- ered and protected by a prolongation of the large sacr. sciatic lig., as far as the crus penis. Ram. First Stage. 1. Vesical, prostatic, and sometimes the middle hsemorrhoidal. Second Stage. 2. Anastomotic, anas, with the ischiatic and int. circumflex art. ; 3, musculares, to the flexors at the tuber ischii. Third Stage. 4. Ext. hsemorrhoidales, two or three to the anus ; 5, perineal (superf.) pierces the middle fascia of th e permseum to get into the space between the accel. urinse and erect, penis m. ; it ascends to the septum scroti, which, and the superficial parts of the peri- neum, it supplies; 6, transvers. perinea (superf.) to the perinaeum and anus; 7, corp. bulbosi (deep trans- verse perinosal,) runs inwards behind the middle pe- rinseal fascia, to the bulb, Cowper's glands, &c. Terminal Branches. 8. Corp. cavern, to those bodies ; 9, dorsalis penis the two latter anas, by a cross branch, or unite into a single vessel; then pierce the suspensory ligament, and run on the dorsum of the penis as far as the glans. The internal iliac art. is accompanied by its vein, which lies anterior and internal to it ; behind it is the 166 FEMORAL ARTERY. sacral plexus, with whose branches those of the art. interlace, and still more posteriorly the origins of the pyriformis muse. EXTEKNAL ILIAC extends from the sacro iliac joint, to the inf. edge of Poupart's lig., in a line leading from a point half an inch external to its middle, to the umbilicus. Rel. bound down by a process of the iliac fascia ; it lies, first, to the inner side, and then on the fore part of, the psoas muscle, to which it is connected by a layer of the iliac fascia; the vein lies on its inner side; close to Poupart's ligament it is crossed by the ilio scrotal nerve. It is surrounded by numerous lym- phatics, and covered by their glands. Ram. a. Epigastric, Or. from any point of the inferior inch and a half of the artery. It first reaches the inner margin of the int. inguinal ring, and then as- cends inwards between the peritoneum and fascia transversalis ; it soon enters the sheath of the rectus m., in which it term, about an inch on the outer side of the umbilicus. Rel., the spermatic cord lies in front, the vas deferens looking round it to descend to the vesic. semin. Ram., 1, cremasteric to that structure and the scrotum ; to the round lig. in the female ; 2, anastomotic, anas, with its fellow and the obturator art. ; 3, terminal anas, in the rectus, with the int. mammary art. b. Circumflexa ilii (internal,) outwards, along Pou- part's lig. and crista ilii ; anas, with the last lumbar, and the ilio lumbar art. FEMORAL ARTERY extends from the termination of the ext. iliac to the lower third of the thigh, in a line leading from the middle of Poupart's lig. to the inner side of the inter- nal condyle of the femur. Rel. at the upper third of the thigh it lies in a triangle (Scarpa's) formed by PROFUNDA. ARTERY. 167 Poupart's lig., the sartorius, and add. longus, covered only by skin, fascia, and glands ; at the middle third it is covered by the sartorius. It rests on the tendon of the psoas and iliacus m.,pectineus, and adductor longus m. The vein and artery are enclosed in a sheath from the fascia lat. This sheath becomes a strong fib. canal, where the vessels rest on the tendon of the adductor longus, beneath the sartorius muscle. The vein, at first on its inner side, gets more and more behind it as it descends ; the ant. crural nerve sends its saphenous branch into the upper part of its sheath : the vena saphena runs between the skin and fascia, a little to its inner side. Ram. a, Superficial epigastric and superficial circumflexa ilii, to the abdominal integuments; b. super/, pudic, two or three running beneath the fascia to the scro- tum; c, muscular super/., to the iliacus, psoas, and rectus m. d. PROFUNDA, Or. generally an inch or an inch and a half below Poupart's ligament. It is placed behind, and separated from the femoral by the pro/un. and /em. veins, and ad. long. Ram. 1, ext. circumflex, passes between the sartorius and rectus m., divides into a transv. branch to the hip-joint and muscles, and a ram. descend., which runs between the rectus and crureus, as far as the knee; 2, intern, circumflex., passes backwards, between the pectineus andr psoas m.; ram. superior to the digital fossa; ram. transv. between the quad. fern, and add. long, to flexor m. 8, perf or antes, three in number 1, super., backwards between the add. brevis and pectineus; 2, media. through the add. brevis and magnus; 3, infer., through the add. magnus, at the upper edge of the add, longus; 4, r. terminal, passes behind the add. longus, and perforates the add. mag. These vessels supply the flexor muscles on the back of the thigh, and form a chain of anastomoses by their ascending and descending branches; 5, anastomotica magna. 168 ANTERIOR TIBIAL ARTERY. Sometimes a large artery ; descends towards the inner condyle, and there enters into numerous anastomoses. POPLITEAL ARTERY extends from the femoral opening in the add. mag- nus to the inf. edge of the popliteus m., in a line descending along the centre of the back part of the knee-joint. It rests in a mass of fatty tissue in a diamond-shaped space, formed above by the diver- gence of the ham-string m., and below by the conver- gence of the two heads of the gastrocnemius. The vein is posterior and external to the art., and the popliteal nerve is in similar relation with the vein. Ram. a. Muscular super., two or three to the ham-string mus. b. Artie, super, ext., winds around the femur, be- neath the biceps tendon, and divides into r. super/., which ramifies on the patella and r. profund. to the synovial membrane and femur. c. Artie, super, int. winds round the inner side of the femur, beneath the inner ham-strings. d. Artie, inf. ext., runs along the edge of the ext. semilunar cart. e. Artie.- inf. ext., winds around the inner side of the tibia. These three art., like the first, divide into superf. and deep branches, which anas, the former on the patella, the latter about the joint. f. Artie, media (Azyga,) perforates the lig. postic. to supply the joint. g. Muscular infer., (Surales,) to the gastrocnemius. The popliteal art. now termin. into the Ant. and Post, tibial art. ART. TIBIALIS ANTIC., runs between the heads of the tibialis post, m., and above the upper edge of the interosseous ligament; descends on its ant. surface, and terminates in the fissure between the tarsal heads of the first and second metatarsal bones. Eel. between EXTERNAL PLANTAR ARTERY. 169 the exten. comm. and tibialis antic, m. above, be- tween the former and exten. prop. pol. below. The nerve runs on its outer side. Ram. a. Recurrent, anas, with the int. artic. a. b. Musculares, adjacent muscles. c. Internal malleolar, and d. ext. malleolar, ramify on those processes. f. Metatarsal, which gives three dorsal interosseous branches. g. Pollicis, supplies the two sides of the first toe, and inner side of the second. h. Communicans (terminal,) joins the ext. plantar artery in the sole of the foot, to complete the plantar arch. POST TIBIAL ABT. descends between the superficial and deep flexor muscles to a point midway between the int. malleolus and os calcis; in its course, it rests successively on the tibialis posticus, flexor communis, and, lastly, on the bone, where it is placed between the sheath which encloses the tendons of the two last named muscles, and that of the flexor prop, pollicis. Ram. a. Peroneal, descends between the inner edge of the fibula and attach, of the flexor pollicis m. to the ext. malleolus. Ram,. 1, ant. peroneal, pierces the interosseous ligament to reach the tarsus ; 2, terminal, to the outer malleolus, &c. b. Internal plantar art. runs upon the upper sur- face of the adductor pollicis m. to the integuments of the great toe; sometimes it joins a branch from the next vessel, to form a superficial plantar arch. c. Ext. plantar art. runs first to the tarsal end of the fifth metatarsal bone, and then across the foot next the interosseous muscles, to join the communicans of the ant. tibial, and form the principal palmar arch. Ram. I, per for antes, three in number; they pierce the interossei to join the interosseous branches of the me- tatarsal artery ; 2, digital, four in number, arise from 15 170 COLLATERAL CIRCULATION. the convexity of the arch, and supply both sides of the three last toes, and outer side of the second. Collateral Circulation. The most remarkable feature in the arrangement of the blood-vessels is their anastomoses. The arte- ries and their branches enter into combinations with each other at every possible opportunity. A. Every artery anastomoses with its fellow, ex- cepting some supplying the viscera, and those in the extremities. B. Every artery anastomoses with the vessel im- mediately above and below it. C. Every artery anastomoses with itself by means of its branches, which follow the general rules of anastomoses. As interesting examples of the first may be men- tioned : The anas, between the ant. cerebral art. of the int. carotids by the ant. communicans. 2. Between the obturator arteries, before their exit from the pelvis, by a transverse branch. 3. Between the dorsal arteries of the penis, by a transverse branch. 4. Between the vertebral arteries, which unite to form a single vessel, the basilar. 5. Between the epigastric art., by a transverse branch. 6. Between the ext. carotids, by nearly every one of their branches, which also form the most remark- able examples of the second rule, &c., &c. 7. The intercostals and upper lumbar arteries en- circle the trunk. Examples of the second rule. 1. In the inf. extremity, all the branches of the ext. iliac and femoral arteries form a posterior or principal, and anterior or minor collateral circula- tion, by a chain of anastomoses along the limb, each COLLATERAL CIRCULATION. 171 of which is sufficient to carry on the circulation when the principal trunk is obliterated. 2. In the superior extremity, a chain of anas, may be traced along the margins of the scapula, inner edge of the arm, &c. 3 . From the angle of the eye, along the nose, mouth, face, and median line of the neck ; and, by means of the int. mammary and epigastric arteries, along the chest and abdomen, even to the principal art. of the inf. extremities. 4. Along the oesophagus, stomach, and intestines, an anastomotic chain may be traced from the pharynx to the rectum. 5. Along the spinal cord, by means of the spinal arteries which hold numerous anastomoses through the intervcrtebral formina with the vertebral, inter- costal, lumbar, and sacral arteries. As interesting examples of the third rule may be mentioned, 1. The branches of the external and internal caro- tids; the former in the brain, the latter in the neck. 2. The branches of the coeliac axis, round the stomach; the coronary arteries, round the heart; the ciliary arteries round the iris, between its larger and smaller circles; the branches of the super, and inferior mesenteric arteries, especially the former: the branches of the articular arteries, especially those of the knee-joint. The digital branches in the hand and foot, the branches of the obturator ar- tery round the margin of the obturator foramen, the branches of arteries supplying sphincters, viz., the mouth, anus, &c. A principle of compensation also prevails through- out the arterial system, by which a less than ordi- nary supply from one vessel is balanced by a more than ordinary supply from another. 172 THE VEINS. SECTION III. OF THE VENOUS SYSTEM. As the arteries distribute the blood from the heart to the different parts of the body, so the veins return it back again to the heartland thus the general cir- culation is carried on. As the veins have been generally described with the arteries, it will not be necessary again to enter upon their description; the following will be sufficient. The blood from the brain is returned by the int. jugular ; this is formed by the conflux of the sinuses at the foramen lacerum posterius, passes out through this with the eighth pair of nerves, descends in the neck, lying posterior and internal to the int. carotid art., and thence enters the carotid sheath, where it lies to the outer side of the par vagum and ext. ca- rotid, and in front of the first stage of the subcla- vian art., joins the subclavian vein to form the right vena innominata. The blood from the external parts of the face is returned by the labial vein, which crosses the lower jaw posterior to the labial art., descends in the neck and joins the int. jug., generally sending a branch to join the ext. jug.; this vein returns the blood from the temporal and int. maxillary arteries, descends in the substance of the parotid gland, becomes su- perficial, crosses the ext. surface of the sterno-mas- toid, and at its outer margin joins the subclavian vein. The blood from the upper extremity is returned by the cephalic, mediam, and basilic veins; the two latter join the brachial venae comites to form the brachial vein at or a little above the elbow-joint; the cephalic runs upwards along the outer edge of the biceps nerve, then between this and the inner edge of the deltoid and the pectoralis major, and joins the axiliary vein a little below the clavicle ; the axiliary vein conducts the POPLITEAL VEIN. 173 blood into the subclavian, which unites with the int. jug. to form the vena innominata. The right vena innom. descends almost perpendicu- larly into the thorax, and after a course of about an inch and an half joins the left to form the vena cava superior. The left vena innominata passes obli- quely downwards and inwards, crosses the upper edge of the arch of the aorta and the vessels arising from it, and on the right side joins the right vena innom. The vena cava superior receives the vena azygos, perforates the pericardium, and empties itself into the right auricle of the heart. The blood from the lower extremities is returned from the foot and leg by the venae comites accom- panying the arteries, which unite to form the pop- liteal vein. The blood from the superficial parts is returned by the int. and ext. saphenoe veins; the int. saphena is the larger, it arises about the inner ankle, ascends in the superficial fascia along the inner side of the leg immediately behind the inner edge of the tibia, crosses along the inner surface of the knee- joint, ascends along the front of the thigh, and a short distance below Poupart'slig. perforates the cribiform fascia, and joins the femoral vein; it is accompanied in the leg by the int. saphenous nerve. The ext. saphena vein arises about the outer ankle, ascends along the back part of the leg beneath the fascia, and joins the popliteal vein; it is accom- panied by the ext. saphenous nerve. The popliteal vein terminates in the femoral, which ascends with the femoral art. and terminates in the ext. iliac vein ; this joins the int. iliac to form the common iliac vein on each side; the left common iliac vein, longer than the right, passes obliquely to the right side, and unites with the right behind the iliac art. and aorta to form the vena cava inferior; the right com. iliac vein passes upwards, behind its art., to form the vena cava inferior. 174 THORACIC DUCT. The vena cava inferior ascends in front of the lum- bar vertebrae, to the right side of the aorta, passes obliquely outwards to the right side, sinks into a deep sulcus or canal in the liver, perforates the dia- phragm, receiving here the venae cavse hepaticae, and almost immediately perforates the pericardium, and empties itself into the right auricle of the heart. The vena porta returns the blood from the organs of digestion, or chylopoietic viscera, passes across the spine behind the pancreas, being here formed by the junction of the splenic and superior mesenteric trunks, enters the transverse fissure, and divides into two branches to ramify in the right and left lobes of the liver; its blood is returned by the venae cavse hepaticae. The renal veins terminate in the inf. vena cava; the lumbar veins in the vena azygos. The larger arteries are accompanied by one vein, the smaller by two, one on each side, the vena comites . The pulmonary arteries carry black blood, the pulmonary veins red or arterial blood. In the foe- tus the umbilical vein carries red or pure blood, the renal* arteries black or impure blood. SECTION IV. The Lymphatic System. The Lymphatics are divided into the lymphatics properly so called, and the lacteals. The lympha- tics proceed from the lower extremities, accompany- ing the superficial and deep veins, pass through the lymphatic glands and join the pelvic lymphatics, and then unite in front of the second or third lum- bar vertebra, behind the aorta and vena cava, to form the thoracic duct. The lacteals arise from the small intestines, pass through the mesenteric glands, and join the preceding to form the thoracic duct. The Thoracic duct, the trunk of the lymphatic sys- tem, passes upwards through the aortic opening of *See Errata. RIGHT THORACIC DUCT. 175 the diaphragm, between the aorta on its left and the vena azygos on its right, and enters the post, medi- astinum to terminate in the left subclavian vein, as described with the post, mediastinum. The lymphatics of the right side of the heart and neck, and right upper extremity, unite to form the right thoracic duct, which terminates in the right subclavian vein. 176 CHAPTER VIII. NERVOUS SYSTEM. The Nervous System consists of the brain and spi- nal cord (cerebro-spinal axis,) cerebral and spinal nerves, and the sympathetic or ganglionic system. The brain and spinal cord are lodged in the cranium and vertebral canal, which are lined by a fibrous mem- brane (dura mater,) and a serous membrane (arach- noid, ) for their reception. They are further covered by an immediate vesting membrane (the pia mater.) The Spinal Cord. When the spinal canal, and the above-mentioned coverings are laid open, the cord and the roots of the spinal nerve are seen covered by a shining investment (neurilema.) The cord extends from the pons Varo- lii to the second or third lumbar vertebra, where it expands, and then terminates in a lash of filaments forming the cauda equina. The spinal portion com- mences at the foramen magnum, the portion above that point being called medulla oblong ata. The spinal portion does not occupy the whole of the canal formed for it by the vertebrae and dura mater, a considerable interval filled with fluid existing between them ; it is, however, in some degree fixed, and its direction made to correspond to the curvatures of the spinal column, by means of the lig.denticulatum. This lig. is an ex- ceedingly thin fold of the arachnoid membrane en- closing a few fibres, and extending the whole length of the cord ; its inner edge is firmly attached to the neuri- lema, between the ant. and post, roots of the spinal nerves; its outer edge is serrated, the teeth being at- tached to the dura mater, in the intervals between the sheaths which it furnishes to the several pairs of nerves at their exit through the intervertebral fora- ANTERIOR MEDIAN FISSURE. 177 mina. The first tooth separates the vertebral artery from the hypoglossal nerve, and is attached to the occipital foramen : the last, which is the twentieth or twenty -first, is attached to the vert, opposite to the termination of the cord. The cord is not of the same size throughout, but presents three remarkable swell- ings, which corresponds to the great nervous plexuses. The first, medulla oblongata, is in the cranium ; the second extends from the third cervical to the fourth dorsal vert. ; and the third commences at the first lumbar vert., or a little higher up, and forms the termination of the cord. The nerves of the tongue, of respiration, and most of those of the face, arise from the first; the nerves of the super, extremity from the second ; and those belonging to the infer. extremity from the third. The cord and nerves are closely invested by a dense, fibrous, but vascular, neurilema, analagous in situa- tion to the pia mater, but much thicker and stronger; it sends processes from its inner surface to surround the constituent fibrils, and its outer surface is co- vered by a mesh of vessels, which reach the cord through numerous foramina, between .the fibrous fila- ments of which it is composed. The membrane is thrown into numerous zigzag folds, in order to allow of temporary extension produced by the various mo- tions of the body ; above, it is gradually lost in the pia mater; below, it terminates in a thin, but resisting, fibrous cord, which is attached to the dura mater lining the sacrum and coccyx ; this cord, formerly considered , a nerve, serves to fix the lower portion of the spinal marrow. The exact figure of the spinal cord is better seen when deprived of its neurilema. It is composed of two symmetrical lateral portions, which are sepa- rated before and behind by two fissures. The ant. median fissure penetrates the third of the thickness of a cord : its floor is formed by the com- missure of the cord a simple band of homogeneous 178 LATERAL TRACTS. white matter, perforated by a vast number of minute vessels, extending from one half of the cord to the other. The post, median fissure is much narrower, and rendered almost indistinct by the neurilema ; nor is it so deep as the former, excepting at the upper part of the cord ; instead of a layer of white, a thin layer of cineritious matter is seen at the bottom of this fissure. On the side of the cord immediately external to the posterior roots of the spinal nerves, a line of gray matter exists, which by cautious examination, will be found to pass down to the central cineritious layer above mentioned. This post, lateral cineritious line subdivides the cord into an antero-lateral, and a post, tract. Immediately external to the ant. roots of the spinal nerves a faint line may also be traced; but here the substance of the cord must be broken, to ar- rive at the antero and lateral cinerit. line, which also reaches the central layer. If this be considered an established line of demarkation, we shall have each an- tero lateral tract anatomically subdivided into an ant. tract and a lateral tract, according to Bell and Bel- linghcri; the latter being included between the ant. and post, roots of the spinal nerves. The disposition of the cineritious matter, which is not the same in 'all parts of the cord, is seen by a transverse section. Its fundamental figure is sufficiently well represented by two crescents united by a transverse line ) (. The transverse line is the layer at the bottom of the post, fissure, and the horns correspond to the ant. and post, lateral cineritious lines. Each half of the cord appears to be a riband-shaped layer of medullary matter, curved round the cineri- tious substance. This medullary riband is separable into two portions, the antero-lateral and post, tracts, which may be further divided into a series of wedge- shaped bundles of medullary fibres, which extends the ,,hole length of the cord. The bases of the wedges are turned outwards and the apices inwards ; they are ANTERIOR PYRAMIDS. 179 united by their sides, and so give the medullary riband, which they form, the proper incurvation. The apices of these wedges are not ranged in a uni- form curved line; the consequence of this irregu- larity is a denticulated appearance of the outer sur- face of the cineritious layer. Medulla Oblongata, or Bulb. The medulla oblongata is that portion of the cord extending from the margin of the foramen magnum to the pons Varolii. In shape it resembles a quadri- lateral pyramid, with its base above and its apex below. The ant. surface presents a median fissure, not so deep as that in the cord; below it is inter- rupted by the decussation of the ant. pyramids; above it terminates at the pons, in & foramen csecum. The ant. tracts of the cord here presents two bodies, which are called, from their shape and position, The anterior Corp. Pyramidalia. These bodies are as long as the medulla, and lie on each side o^ the ant. fissure; they commence be- low by their narrow extremities, which is about a line and a half in thickness, and ascend, gradually diverging to the pons, where they are twice that in size; they then suddenly diminish to pass above that substance. The c. pyram. are composed of white fasciculi, and appear, although considered by Ro- lando as indistinct superadded bodies, to be the ant. tracts of the cord, augmented by fresh nervous matter. The decussation of the ant. Pyramids. This remarkable interchange of filaments of the anterior pyramids takes place about the lines below the pons, it is formed by three or four large fasci- culi, which regularly and successively intercross. The decussation comprehends the ant. two-thirds of the medulla, and also takes place from before, back- 180 FILAMENTA ARCIFORMIA. wards, as the ant. portion of the ant, tract, or pyra- mid of one side, may be traced backwards to be con- tinuous with the more lateral fasciculi of the other. No other decussation exists in the medulla. Corpora Olivaria. These two bodies are situated external and some- what posterior to the ant. pyramids. They are two white oval eminences about six lines long, embedded to half their diameter in the medulla; in fact, they are inserted between the anterior and post, tracts, and are only separated from each other at the median line by antero-poster. transverse filaments, the con- tinuations of which (fila. arciformia) bind them, as it were, in their situation: they contain a layer of gray matter, crumpled into a kind of concentric frill. Corp. Restiformia; post, pyramids; infer. Cerebellar Peduncles. The posterior tracts of the cord bear these titles; they ascend diverging on the post, surface of the medulla, till they reach the cerebellum. The post, fissure is converted into a triangular depression (fourth ventricle] by their divergence. This ventri- cle, like the post, fissure, is lined by cineritious mat- ter, marked by a few medullary stride, so as to bear altogether a vague resemblance to a pen (hence calamus scriptorious ;) a median furrow represents the stem, the medullary strise the feather, and the commencement of the divergence the point. Filamenta Arciformia, a term given by Santorini to some medullary filaments leading from the anterior to the posterior tracts; they are important, because they show that the infer, cere- bellar peduncles are not formed solely o" the post, tracts. The antero-post. fibres, before mentioned, wind horizontally round the ant. pyramids, and pass, CRURA CEREBRI. 181 one set of fibres immediately below the corp. olivaria, and another on the inner side of those bodies, to the corp. restiformia. Similar, but deeper seated, fibres are described by Mr. Solly, to cross and obliterate the post, cineritious line, and then join the restiform bodies. Fasciculi Innominati. When the ant. and post, pyramids are removed, a dense grayish white substance is seen to occupy each half of the cord; like the olives, they are only sepa- rated by the ant. post, fibres. This substance, which is continuous with the corresponding lateral tract, is prolonged to the optic thalami, &c. Isthmus. The medulla oblongata is connected to the cerebrum and cerebellum by certain prolongations whichoccupy an intermediate situationbetween them. The isthmus comprises the crura, or pedunc. cerebri, the contin. of tkefascic. innom. the super, and middle peduncles of the cerebellum, ports Varolii, tuber cula quadrigemina, and valve of Vieussens. The pons Varolii is a mass of medullary matter of a square shape, resting upon the basilar process of the occip. bone, and supporting the anterior pyramids in their passage to become the crura cerebri. Its ant. and post, edges are free, but latterally it ascends on each side of the crura to constitute the middle pedun- cles of the cerebellum. A section of the pons shows it to be composed of antero-posterior and transverse me- dullary fibres, intermixed with gray matter, which gives each slice a striated appearance; the former fibres belong to the crura, the latter to the middle pe- duncles. The inferior surface is marked by a groove, which is caused by the projection of the two corp. pyramidalia; it generally lodges the basil, art. The peduncles of the cerebrum, or crura cerebri. are 16 182 TUBERCULA QUADRIGEMINA. two Irirge white round cords about six inches long, which continue the ant. pyramids in the cerebrum. They diverge in proceeding to that organ, leaving a triangular space, which anter. is occupied by the corp. inammil. and tuber, cinereum, and poster, by the inner portion of the fascic. innom. Each crus is often in- tersected by two perpendicular white tracts, one from the testes and valve of Vieussens, the other from the inner surface of the crura. The crura are separated from the fascic. innom. by a stratum of dark gray matter (locus niger;} their size is strictly relative to that of the corresponding hemispheres. Peduncles of the cerebellum. The inferior are the two corp. restiform, strengthened by the fili. arci- form. the middle are constituted by the prolongations of the pons, which might be called their commissure; the superior, pedunc. processus cerebelad. testes: inter- cerebral commissure, are two lamellae which arise in the substance of the lateral lobes of the cerebellum, on each side of the median line, and extend upwards and forwards, apparently to terminate in the testes. They form the ceiling of the aqueduct of Sylvius, and their inner edges, which are proximate, are united by the valve of Yieussens. Valve of Vieussens. A thin semi-transparent la- mella, which unites the adjoining edges of the sup. cerebellar peduncles. It also covers the aqueduct of Sylvius. Tubercula Quadrigemina. These are four roundish eminences, placed two on each side of the median line, behind the thalami ; the anterior two are called nates, the posterior two testes. The former are oblong, and of a grayish colour, the latter are rounder, and more inclined to white. In animals they constitute the optic tubercles, and are in some joined into a single pair; they are single in the foetus, and in the adult the separation is not complete. The nates are united to the thalami, and the testes to the intercerebral FOURTH VENTRICLE. 183 commissure. On the outer side of the thalami, a lit- tle anterior and below the tubercula quadrigemina,are two little swellings called corpus geniculatum, externum and internum, the lateral tracts strengthened by fascicul. innom. and a fasciculus from each c. oliv. terminate in these tubercles and thalami the whole may therefore be considered as one connected system. Cerebellum. The cerebellum is placed in the inferior occipital fossae, beneath the teritorium, which separates it from the posterior lobes of the brain. It is elliptical in shape, and composed of two symmetrical halves, or lobes, united at their fore part by an intervening me- dian lobe. The lateral lobes are separated behind, and below, by a median fissure, which receives the f alx cerebelli; below and in front, the fissure dilates into a notch, which partly encloses the back of the medulla oblongata. When the lateral lobes are pulled apart, the median lobe is seen continuous. on each side with the former, and its two halves united by a promi- nent median raphe. The Super. Vermiform process is this raphe on the upper surface of the lobe ; it is prominent in front, and covers the valve of Vieussens; behind it is almost lost, where it joins the infer, vermiform process, or under part of the raphe, on the back of the lobe. The Infer. Vermiform P. is marked by a few rings, it is seen in the middle of the notch, and forms the post, paries of the fourth ventricle, into which pro- ject several unimportant eminences, designated by a few meaningless terms. The Fourth Ventricle. This is a rhomboid shaped cavity, extending from the aqueduct of Sylvius, by which it communicates with the third ventricle to the pointof the calamus, where it presents an orifice leading into the sub-arachnoid cellular tissue. It is bounded below and in front by the fascia innom.; laterally by 184 CORPUS RHOMBOIDEUM. the peduncles of the cerebellum, above, by the sup. peduncles of the cerebellum, valve of Vieussens, me- dian lobe, and inf. vermiform process, and neurilema of the cord. The Aqueduct of Sylvius runs beneath the valve and super, pedunc. to the third ventricle. The inf. orifice is rendered interesting by the recent researches of Magendie, on the seat of the cerebro- spinal fluid. The superficies of the lobes of the cerebellum is grooved by numerous horizontal curved lines, which divide the organ into a number of segments and lamel- lae, analogous to the convolutions of the cerebrum, laid one on the other like the leaves of a book. The con- tinuity of these lamellae is not interrupted at the me- dian lobe, but are merely drawn out of their direction as they pass from one lateral lobe to the other; the antero-post. vertical section of the median lobe shows its arbor vitse. This appearance is produced by two medullary trunks, super, and inf. springing from a central medullary nucleus, and dividing into many orders of branches. The primary branches, six in number, correspond to so many segments of the organ; each segment divides into smaller segments, lamellae, and lamellules ; the latter are extremely irregular. A stratum of cineritious substance invests these divi- sions, and dips in the intervals between them. Similar sections of the lateral lobes display an arbor vitoe, with branches of the same character to each of them. By attentive examination, the nuclei and their medullary ramifications, are discovered to be composed of medul- lary plates, two of which, at least, enter into the forma- tion of the smallest lamellule. In the centre of each of the lateral nuclei is a small round body, corpus rhomboideum, or ganglion of the cerebellum, resem- bling the c. olivaria, particularly in the arrangement of the stratum of gray matter which it contains. The peduncles of the cerebellum, three on each side, en- ter into, or proceed from the lateral nuclei. OPTIC TRACTS. 185 Cerebrum. The cerebrum is that part of the nervous mass which fills the entire cranium, excepting the inferior occipital fossae. The greater part of the brain is composed of convolutions, which spring as it were from the isthmus, situated on the basilar process and body of the sphenoid, and extend in every di- rection till they entirely fill every corner of the cranium. The superior surface of the brain is di- vided into two symmetrical lateral halves, or hemis- pheres^ by a deep median fissure, which receives the falx major. The whole of this surface, and those of the hemisphere next the falx, are marked by longi- tudinal elevations and depressions (Circumvolutions and sulci, ) which have their corresponding depres- sions, digital fossse, and elevations on the interior of the skull. The greater part of the infer, surface is also formed by the convolutions of the hemispheres, which are here subdivided into three lobes: the ant. lobes rest upon the orbitar processes of the frontal and smaller wings of the sphenoid bone ; the middle lobes are lodged in the sphenoidal fossse, the post, lobes on the tentorium. The ant. are separated from the middle by a deep fissure (Sylvii;) but the line of demarkation between the middle and the posterior lobes is merely a faint line, produced by the upper- edge of the petrous bone. The anterior and poste- rior lobes are only separated by the ant. and pos- terior continuations of the great median fissure ; but the middle lobes have between them, resting upon the basilar process and body of the sphenoid, the isthmus and several remarkable eminences, seen on the base of the brain: viz. Optic Tracts. Two fasciculi of white matter, which arise on each side of the corp. genie, ext., wind round each crus at the point where it terminates in the cor- pus striatum, and then run inwards and forwards to 16* 186 PITUITARY GLAND. form the commissure of the optic nerves on the olivary process of the sphenoid bone. These fasciculi, with the crura cerebri, intercept a lozenge-shaped space, which contains the fascic. innominati, c. mamtnillaria, tuber, cinereum, infundibulum, and pituitary gland. Interpeduncular space ; or space left by the diver- gence of the crura, is occupied behind by the lower surface of the fasciculi innom., in front by the c. mam. Corpora Mammillaria. Two small round white eminences, situated between the crura, their ant. sur- face imbedded in the tuber, cinereum, 4 heir posterior in the fascic. innom. Although tolerably distinct be- low, they are united above by a soft gray substance, which forms part of the floor of the third ventricle. They are composed of a central portion of gray, co- vered by a cortex of white matter, apparently derived from the anterior pillars of the fornix. Tuber cinereum. A soft gray substance which fills the interval between the corpora mammil. and the optic, fascic. and their commissure. It is a continua- tion of the soft substance which unites the c. mam. and with it forms part of the floor of the third ven- tricle. Infundibulum. A reddish cord, about two inches in length, directed downwards and forwards from the tuber cinereum, to the ant. lobe of the pituitary gland, to which its apex is attached. It contains a fun- nel-shaped canal, which above commun. with the third ventricle, but ceases at the gland. It is com- posed of a cylinder of fibrous pia mater, lined by the same soft gray substance as is seen in the third ven- tricle. Pituitary Gland. A small body of grayish white substance, weighing from five to ten grains; it is si- tuated in the sella turcica of the sphenoid bone, where it is confined by the circular and cavernous sinus, and a fold of dura mater. It is composed of an anterior larger, and post, smaller lobe, separated by a fibrous FISSURE OF SYLVIUS. 187 membrane. They both contain numerous small vessels. The commissure of the optic nervesbeing removed, the anterior part of the floor of the third ventricle is exposed ; it is formed by that soft gray substance which is a continuation of the tuber cinereum, it is covered by the neurilema of the optic nerves, which seem to derive a few filaments from it. A little more in front is the ant. reflected extremity of the corp. callosum, joining the anterior lobes of the brain ; still more in front the ant. and inf. portion of the great median fissure. Behind the pons Varolii is the post, and inner, ext. of the great median fissure, which when widened, shows the post, extremity or bulb of the c. callosum, uniting the post, lobes. Between the bulb and the upper surface of the c. quadrigemina is a fissure, where the pia mater, as the tela choroidcs, enters the ventricles. This is the fancied situation of Bichat's celebrated arachnoid foramen, which does not exist (Cruveilhier.) Here also, surrounded by the tela choroides, is the pineal gland. The pia mater also enters the ventricles by another fissure, (Grande fente celebrale, Bichat,) which extends on each side, from the extremity of the former, to the fissure of Sylvius. It enters the lateral ventricle between the hemisphere and outer sides of the thalamu^s. It only admits the pia mater. Fissura Sylvii. The fissure corresponds to the wing of Ingrassias, and commences at the ant. end of the grande fente, extending outwards, so as to form a deep interval between the ant. and middle lobes. It contains the middle arteries of the cerebrum. The angle of the middle lobe, formed by the junction of the two above-mentioned fissures is called subs, perforata: it is white, and pierced by numerous small vessels. 188 THE FORNIX. INTERNAL CONFORMATION OF THE BRAIN. Corpus callosum, (grand transvers e commissure:) (ex- posed by a horizontal section on a plain a little above it, or, by separating the hemispheres ;) it is a stratum of medullary matter, about three and a half inches long, uniting the two hemispheres, at the bottom of the median fissure. The upper surface, convex, pre- sents a median furrow produced by two parallel longitudinal strata of white matter, formed by the arteries resting here; under these are perceptible numerous transverse fibres, of which this commis- sure is principally composed. The infer, surface, concave, covers the lateral ventricles, and also pre- sents longitudinal fasciculi; anteriorly, in the median line, it receives the septum lucidum, sent up from the fornix; posteriorly it joins the latter body, and ter- minates just above the c. quad, in a bulbous extre- mity, which unites the post, lobes: anteriorly it is re- flected over the c. striata and terminates beneath them just in front of the third ventricle, where it unites the ant. lobes. Two white fasciculi (peduncles of the c. cal.) run, parallel to the optic fasciculi, from this extremity to the subs, perforata before mentioned, Fornix; longitudinal commissure. A triangular medullary arch in the lateral ventricles, resting upon the thalami. It is composed of two lateral fasciculi joined in the median line. The apex of the fornix ter- minates in two fasciculi, (ant. pillars,) or continua- tions of the lateral fasciculi, which arch over the fore part of each thalamus as the corpus callosum did over the c. striata ; descend between those two bodies, through the gray matter on the sides of the lateral ventricles and behind the ant. commissure, to the c. mammillaria, to form the medullary cortex ; the post, angles are continued as thepost. pillars, outwards and downwards in the lateral ventricles, to form the corp. fimbriata. The base is attached to the bulb of the corp. CORPUS STRIATUM. 189 callosum. Between the upper surface of the thala- mus and ant. pillar on each side, a space (for. Mon- ro) is left, by which each lateral communicates with the third ventricle. Septum Lucidum. The triangular interval between the fornix and corp. callosum is closed by two deli- cate semi-transparent lamellse, which are sent up from the contiguous edge of each half of the fornix, to the under and fore part of the corpus callosum. The interval beween them is called the fifth ventri- cle, which sometimes contains a few globules of fluid : it does not communicate with the other ven- tricles. The septum lucidum separates the lateral ventricles. Lateral Ventricles. Exposed by dividing the corp. callosum on each side of the septum lucidum. They commence in each anterior lobe a little before the beginning of the third ventricle, forming the anterior cornu, run upwards and backwards, and a little be- yond the termination of the third vent., turn round the post, part of the thalamus, beneath which they are reflected, to terminate in the middle lobe, close to the fissure of Sylvius, only a little below and be- hind where they commenced, forming the inferior cornua. At the point of reflection it sends a pro- longation (digital cavity) into the posterior lobe, forming the posterior cornua. The superior, or straight portion of the lat. ventricle. The floor of this portion is formed by the upper surfaces of the corresponding corp., striatum, and optic thalamus. Corpus Striatum. A grayish, pyriformbody deeply embedded in the fore part of the floor of the lateral ventricle. Its largest extremity lies in front of the thalamus, but behind it runs tapering along the outer side of that body to the point where the lateral ven- tricle begins its reflection. Internally it corresponds to the gray matter which forms the sides of the ant. 190 THIRD VENTRICLE. part of the third ventricle, and to the outer side of the thalamus. Below, it sinks deeply into the post, and inner part of the anterior lobe. Its interior presents a remarkably striated appearance, produced by the diverging fibres of the cerebrum, of which it is sup- posed to be the great ganglion. Thalamus nervi optici. An oblong brownish-white body, situated in the floor of the lateral ventricle, behind and internal to the c. striatum. Its ant. ex- tremity is separated from the c. striatum by the ant. pillars of the fornix, and its outer side from that body by the tenia semicircular h. Its inner sur- face forms part of the side of the lateral ventricle. It is covered by the tela choroides and inf. surface of the corresponding lateral stratum of the fornix ; its interior is composed of gray matter. The tenia semicircularis is a narrow white band, separating the corp. striat. from the thai. : it is covered by a vein which is enclosed in a fold of the lining membrane of the ventricle. In the inf. or reflected portion of the lat. ventricle, is 1, hippocampus majors cornu ammonia a portion of a convolution projecting from the floor; 2, corpus fimbriatum, a narrow dense band, a prolongation of the post, pillar, or angle of the fornix which runs on the hippocampus. In the post, portion, or digital cavity, is seen the hippocampus minor, also a projecting convolution. It is connected to the h. major by a narrow band which is also connected with the fornix. Third Ventricle. This is merely a fissure separating the optic thalami. Behind and above, its sides are formed by these bodies, but before and below it is lined by a peculiar soft gray matter, which is continuous with the tuber cinereum. The floor, concave, is constituted posteriorly (between the crura, ) by the fascic. innom. ; in the middle by the tuber cinereum, c.mammil. and infundib. ; anteriorly PIA MATER. 191 by the reflected portion of the c. callosum. Its sides are united by three commissures viz. 1, com. mollis, a soft gray substance like the tuber ciner., situated just in front of the thalami; 2, com. ant. a white cord just in front of the ant. pillars of the fornix, uniting the thalami ; 3, com. post, a similar cord uniting those bodies just in front of the t. quadrigemina. The aqueductus Sylvii is a canal leading under the tuber quadri. from the third to the fourth ventricle. The third ventricle contains, 1, the opening of this aqueduct ; 2, that of the infundibulum ; and 3, 4, the foramen, or foramina of Monro. Pineal Gland. A small conical body resting on the fissure separating the t. quadri., just behind the post, commissure. Its base is attached to the tha- lami, by two peduncles, which are also attached to a white stratum (Pineal comm.,) which extends be- tween the thalami, above the post, commissure. It frequently contains irregular concretions of phos. lime and animal matter (Pfaff,) and is closely in- vested by the tela choroides. Membranes of the Brain. The surfaces of the brain are supplied with blood by a vascular membranous network, (pia mater,) which dips between all the convolutions, and enters the ventricles, where it forms thick vascular meshes, (plexus choroides ^) which also receives additional arte- rial branches from the base of the brain. The tela choroides spreads over the third ventricle and tha- lami, but under the fornix, the pia mater enters into post, fissure to form it: it dips into the third ventri- cle to form its plexus choroides, and enters the lat. ventricles through the foramen of Monro on each side to form a choroid plexus for each of them. The pia mater also enters the lat. vent, through the grandefente. The plexus of the third passes through the aqued. of Sylvius, to form the plexus ch. of the fourth ventricle. 192 SINUSES OF BRAIN. Dura Mater. This is a strong fibrous membrane, which, lines the skull as a periosteum to the bones, and sends septa to separate and support the different divisions of the nervous mass. The construction of these partitions is best understood by supposing a fold of membrane to be pinched up on the line occupied by these septa, and drawn, more or less, into the interior of the cavity. The falx major separates the two hemis- pheres; it commences by its point being attached to the crista galli of the ethmoid bone, and its base is continuous on each side with the upper lamina of the tentorium. Its upper, or cranial edge, convex, is attached along the inner mesial line of the cranium, and contains the super, long, sinus; its lower edge, concave, is free, and contains the inf. long, sinus. The tentorium separates the cerebrum from the cere- bellum ; its circumference, or cranial edge, corres- ponds to the lateral occipital grooves, upper edge of the petrous bone, and it term, at the post, clinoid pro- cesses ; its inner crescentic edge surrounds the me- dulla oblongata, its horns being prolonged, under the terminations of the outer edge, to the ant. clinoid pro- cesses. The falx cerebelli separates the lateral lobes of the cerbellum : its upper portion, or base, is continu- ous with the inf. lamina of the tent. ; it terminates by a pointed end at the foramen magnum. The dura mater consists of two membranes, the inner one forming the septa, the outer one remain- ing attached to the bone; it is lined internally by a reflexion of the arachnoid membrane, externall} 7 it is closely connected to the inner surface of the bones of crunium by numerous vessels. The sinuses, fifteen in number, are composed of the inner membrane of a vein enclosed between these two layers. 1, The super, longitudinal sinus, corresponds to the DURA MATER. 193 cranial edge of the falx : it contains the cordse Willisii, which are said to preserve its venous orifices patent ; 2, infer, longitudinal sinus, inf. edge of the falx; 3, 4, lateral sinuses, cranial edge of the tentorium; 5, straight sinus, contin. with the inf. long, sinus, runs in the diamond shaped canal, between the conjoined laminse of the falx major, minor, and tentorium ; 6, 7, cavernous sinuses, on each side of the sella turcica ; traversed by the third, fourth, first branch of the fifth and sixth pair of nerves ; the carotid artery, and caro- tid plexus of the sympathetic, all of which are sepa- rated from the blood by the venous membrane; 8, 9, inf. petrosal sinus, inf. or occipital angle of the petrous bone; 10, transverse sinus joins the last two across the basilar process; 11, 12, super, petrosal sinuses, upper angle of the petrous bone; 13, circular sinus, sur- rounds the pituitary gland, communicating on each side with the cavernous sinuses; 14, 15, occipital si- nuses, occipital foramen. The straight sinus receives the inf. long., s. vena Galena, and the inf. and middle cerebral and cerebel- lar veins. The petrous sinuses receive the cavernous, circular, and transverse sinuses. The lateral sinuses receive, 1, the super, long, s., straight s., and two occi- pital sinuses, opposite the occipital tuberosity, the conflux being termed torcular Herophili; and 2, the petrosal sinus at some point of their course to termi- nate in the int. jugular veins. The dura mater descends through the foramen mag- num, to which it closely adheres in the vertebral canal as a sheath, which encloses the spinal cord, and forms a distinct sheath for each pair of spinal nerves. It is loosely attached by means of distinct ligamentous slips to the post. comm. lig., but a peculiar reddish semi-fluid fat, traversed by many vessels, separates it from the arches and lig. subflava ; below it forms a large sac, which surrounds the chorda equina, and is distended by the cerebro-spinal fluid. A large space 17 194 STRUCTURE OF BRAIN. exists between the sides of the cord and sheath also generally filled with this fluid. The arachnoid is a very fine serous sac placed be- tween the dura mater and pia mater. It covers the convolutions, and is also carried into the third ventri- cle by the venae Galeni, through the post, fissure, it then passes into the other ventricles and infundib. through its four openings. A similar sac is found between the spinal cord and its sheath of dura mater. The arachnoid passes from one convolution to the other without entering the sulci; it is also stretched from the tuber, cin. to the pons, and from the lobes of the cerebellum to the cord, large corresponding spaces are thus left between it and the pia mater, with which the numerous minor spaces between the convolutions and ventricles communicate. The whole of the spaces are filled with the cerebro-spinal fluid. The arachnoid membrane presents a similar ar- rangement in the spinal canal investing the inner surface of the dura mater, and the outer surface of the pia mater, and forms the lig. denticulata. Thepia mater is the immediate investing membrane of the cord, it is much more dense but less vascular than that of the brain. Structure of the Brain. Each hemisphere, by transverse sections, is seen to be formed by a large central nucleus of medullary matter united by means of the corpus callosum. Each nucleus divides into three segments, which subdivide into the convolutions. The convolutions, unlike the lamellae of the cerebellum, are only a few lines (from nine to fourteen) deep, and meander in various direc- tions. In size and sit. a few of them only are constant, most of them differ greatly in different brains. Their use is to augment the extent of surface of medullary matter, and thereby obtain a more extensive stratum of that peculiar gray matter which is supposed to play such an important part in all nervous phenomena. LATERAL TRACTS. 195 Since the beautiful theories of Gall and Spurz- heim, which have given a peculiar tone and direc- tion to all subsequent researches respecting the con- struction of the nervous centres, anatomists are ac- customed, in describing the connections and relations of the diiferent parts of the nervous system, to employ such terms as origin, divergence, expansion, &c., terms which must be understood only as expres- sive of the peculiar views of the various authors who make use of them. The amount of our present real knowledge of the construction of the nervous sys- tem may be stated as follows: 1. The anterior tracts of the cord decussate, by the principal part of their filaments, at the commencement of the medulla oblongata, and may then be traced upwards, first as the anterior pyramids, and then as the crura cerebri, above the pons Varolii, forming the diverging fibres of the cerebrum, to the corpora striata; further, their white medullary filaments may be traced through the gray substance of which these bodies are composed, and to make use of the figura- tive, from the side opposite to that at which they entered, they are seen to diverge forwards, upwards, and backwards, so as to compose much of the medul- lary centres of the hemispheres, finally terminating by being lost in the cortical layer of gray matter. 2. The lateral tracts of the cord becoming fasciculi innom., in the medulla oblongata, and strengthened by two fasciculi from the olivary bodies, ascend pa- rallel to and upon the upper part of the crura (the separation between them being marked by the locus niger) to be continuous without any line of demar- kation whatever with the thalami: they are also connected to the tuber quadri. From the opposite side of each thalamus white diverging fibres are seen to arise, and diverge in all directions, intermixing with the posterior fibres from the corpora striata, like them also to terminate in the cortical gray layers 196 STRUCTURE OF BRAIN. of the convolutions. Some fibres from the thalami traverse the corp. striata. 3. The posterior tracts are continued in the medulla oblongata, as the restiform bodies, or inf. cerebellar peduncles ; these may be still further traced, with- out any decussation, to the central nuclei of the la- teral lobes of the cerebellum, where they pass through the corpus dentatum or ganglion of the cerebellum, and thence diverge to form its hemispheres. Previous to their entrance into the cerebellum it will be recol- lected that they are joined by the filament a arciformia. 4. The convoluted portion of the hemispheres is thus composed of the medullary radiations from the cen- tral nuclei, or corp. striata and thalami, covered by a layer of gray matter. 5. The cerebellum is composed as before stated. The nervous system is made up of two symmetrical lateral halves, united by certain medullary strata called commissures ; thus, 6. The lateral sides of the cord are united by a uniform layer of soft white matter, seen at the bottom of the ant. median fissure. 7. The lateral lobes of the cerebellum are united, 1, by the middle lobe, the raphe of which, seen as the two vermiform processes, indicates that it also formerly consisted of two lateral halves ; 2, by the pons Varolii, which is continued upwards round each crus cerebri, as the middle peduncles of the cerebellum, to the central medullary nucleus of each lateral lobe of that body ; 3, by the valve of Vieussens. 8. The central nuclei (c. striata et thalami) of the hemispheres are united by, 1, the ant. commissure; 2, the posterior commissure; and 3, the Pineal com- missure. 9. The two hemispheres are united by the great transverse commissure, or corpus callosum. 10. Each hemisphere is united in its diiferent parts ; 1, by the inferior longitudinal commissure or fornix, STRUCTURE OF BRAIN. 197 which by its ant. pillars before, and its post, pillars behind, is connected to each lobe ; 2, by the superior longitudinal commissure, composed of longitudinal fibres, which run in the substance of the hemispheres in the same curved lines as (but a little above) the corpus callosum, and 11. The cerebrum and cerebellum are united by the intercerebral commissure, or superior peduncles of the cerebellum. The commissures are formed by the transverse or converging fibres, which arise in the external cineri- tious substance, and pass inwards to the opposite hemisphere. The hemispheres appear to be composed of the me- dullary striae from the corpora striata; of similar striae from the thalami; and striae which are continuous on each side with the transverse fibres of the corpus callosum, all intermixing and radiating in various di- rections till they arrive at the surface of the convo- lutions; the latter are formed by an outer stratum of gray matter, and an inner medullary stratum thrown into a series of folds (convolutions;) each convolution being composed of a rind of this gray and white matter, containing the terminal ends of those nume- rous white striae from the corp. striata, thalami, and c. cal. Comparative anatomy will, in some degree, assist in rendering our knowledge of the brain a little more clear. It is seen, for instan-ce, that the brains of some animals, especially fishes, are composed of two linear series of lobes, which answer to the olfactory lobes, corpora striata, thalami, tubercula quadrigeini- na and middle lobe of the cerebellum, in man. In ani- mals of a grade still lower than those referred to, the brain is composed of little nodules, of less number and size, so that it is difficult in some cases to distin- guish which should properly be called thalamus, &c.; but enough is learned by such a comparative consi- 198 STRUCTURE OF BRAIN. deration of these primitive strata, or accumulations of nervous matter, to show the probable use of the hemispheres and the parts relating to them. The human brain, in fact, consists of certain primitive nuclei, covered by superadditions of nervous matter in the shape of the two hemispheres. If the organ be traced through the phases which it presents at succes- sive periods of foetal existence, the primitive nuclei are observed to become gradually covered by two thin membranes which seem to spring from their sides; they represent the hemispheres: it is not until the hemispheres have nearly finished their progress that the convolutions make their appearance. The corpus callosum, fornix, septum lucidum, the lateral ventricles, and the parts they contain, as the hippocampi, corpus fimbriatum, are dependents of the hemispheres, and therefore are never found when the latter are absent. The uses of the following parts are still enveloped in mystery: 1. Corpora albicantia, absent in birds and reptiles, very large in fishes; supposed to be, like the hippo- campi, a convolution in a different form. 2. Pituitary gland and infundibulum. 3. Pineal gland, or conarium; the seat of the soul (Descartes.) A plug to obstruct the orifice leading from the third to the fourth ventricle (Magendie.) 4. The relative uses of the cineritious and medul- lary structures. Until a period subsequent to birth they are indistinguishable from each other; they ap- pear to be formed simultaneously, and only acquire their distinctive characters at some distant period. It would not be unprofitable to take a general view of this remarkable gray matter in its various relations to the medullary substance, but we have only space to observe, that it is found principally at the central terminations of nerves, and other medullary media, which may thus be considered as mere internuncii. ARTERIES AND VEINS OF BRAIN. 199 The brain is supplied with blood by the int. carotid and vertebral arteries ; the former enter, one at each side, through the carotid foramen, in the petrous portion of the temporal bone, pass through the canal, and ascend by the side of the sella turcica; they here divide into the anterior and middle cerebral posterior communicating arteries. The anterior passes forwards and inwards, is joined to its fellow by the ant. communicating branch, winds round the ant. extremity of the corpus callosuni, and termin- ates in the callos. art. The middle passes upwards and outwards into the bottom of the fissure of Syl- vius, and supplies the ant. and mid. lobes. The posterior communicating branch passes backwards to join the posterior cerebral art., and forms the side of the circle of Willis. The vertebral arteries enter by the foramen mag- num, ascend forwards and inwards, and unite in front of the pons Varolii to form the basillar art. This ascends along the groove in the pons, and at its upper margin divides into the superior art. of the cerebellum and post. art. of the cerebrum, to their destination in the cerebellum and post, lobe of the brain; the latter joins the post, communicating branch, as just described, and thus completes the circle of Willis. Each vertebral art. gives oif, before forming the basilar, two branches, the anterior and posterior spinal arteries ; these descend along the corresponding surfaces of the spinal cord, anasto- mosing with similar branches from the deep cervical, intercostal and lumbar arteries, and the inferior ar- tery of the cerebellum to the under surface of this part. The blood from the brain is collected in the sinuses, and is returned by the int. jug. vein; the veins from the Bpinal marrow form numerous venous plexuses around the transverse processes of the ver- tebrae, and empty themselves into the adjoining ven- ous trunks. 200 NERVES. DIVIDED INTO CEREBRAL, SPINAL, AND SYMPATHETIC. Spinal Nerves. IT has long been considered that the experiments of Sir C. Bell and Magendie have left no doubt, that, of the double roots by which each pair of spinal nerves is attached to the cord, sensation depends on the posterior or ganglionic root, and motion on the anterior ; but it is by no means ascertained that they derive such powers from corresponding tracts of the cord. The cord is stated to be composed of an an- terior or motor portion, and a posterior or sensory portion, which are joined together somewhere in the lateral tract; now the one or other power may be fairly assigned to that point where the anterior and posterior roots are respectively attached ; but the precise origin of them is by no means determined. Cruveilhier denies the existence of different orders of nerves ; he could not even perceive any difference between the result from a division of the anterior, and that from the division of the posterior roots. The spinal nerves are thirty-one in number, in- cluding the sub-occipital. There are eight cervical, twelve dorsal, five lumbar, and six sacral. Origin of the Spinal Nerves. The spinal nerves arise by two linear series of fila- ments from the anterior and posterior cineritious lines and are, therefore, separated by the lateral tracts, and the ligamentum donticulatum. In the adult they can- not be traced into the anterior of the cord, so as to ascertain their precise points of origin, but, through the semitransparent cord of a foetus seven or eight months old, numerous delicate nervous filaments, which compose the anterior and posterior spinal POSTERIOR CERVICAL NERVES. 201 nerves, are seen to traverse the central gray matte r, and may be followed even to the posterior tracts. Immediately after the exit from the cord, the fila- ments divide into sets of eight or ten, which converge so as to form one of the roots of the spinal nerves. The anterior and posterior roots soon approximate, but do not unite, and each is enclosed in a distinct sheath of dura mater. Differences between the two Roots. The anterior roots are smaller, excepting the first, or sub-occipital, whose anterior root is the larger, near the median line, and their filaments are not attached to the cord exactly in the same line. They have no ganglions. The posterior roots are larger, their filaments are attached in succession to the posterior cineritious line, and each presents, when arrived at the corresponding intervertebral foramen, a characteristic swelling or ganglion, which is situated within the foramen. A junction of the two roots now takes place ; the anterior root, however, is not entirely free from the ganglion, which frequently receives several filaments from it. Branches of the Spinal Nerves. The conjoined cord of the two roots divides.into, 1, a middle or ganglionic branch; 2, a posterior branch ; and, 3, an anterior branch. The ganglionic branches belong to the sympathetic nerve. The posterior branches, the smaller, excepting the first two, supply the parts on the back of the trunk. The anterior branches supply the fore part of the trunk, and the extremities. Post. Branches of the Cervical Nerves. The first escapes between the occipital bone and 202 POSTERIOR BRANCHES. atlas, on the inner side of the vertebral artery ; it lies in the triangle formed by the rect. post, major, and obliqui, which it supplies. The second, the largest, escapes between the arches of the first and second vertebrae, beneath the lower edge of the inf. obliquus, and ascends under the cer- vical muscles, which it pierces close to theoccipital artery, to ramify with it on the post, part of the cranium. Ram. to the adjoining muscles. The third, arrived between the two complex! mus- cles, divides into an occipital, and transverse or cer- vical branch. The fourth, fifth, sixth, seventh, and eighth, are much smaller than the former, and after supplying the cervical muscles, terminate in the integuments. The first, second, and third, also form a species of plexus, beneath the complexi muscles. Posterior Branches of the Dorsal Lumbar Nerves. The eight superior branches divide into external, or muscular branches, which subdivide in the space between the sacro-lumbalis and longisshnus dorsi muscles, to supply those m., &c., and musculo cuta- neous branches, which, after a curious winding course, pierce the latissimus dorsi near the spine, and run horizontally outwards to the skin. The four last dorsal, and the five lumbar, pierce the common mass of the long dorsal muscles, supply them, and then wind horizontally round the loins, some under the latissimus dorsi, and some between the layers of abdominal muscles, which they pierce here and there, to terminate on the skin of the abdo- men. The posterior branches of the sacral nerves pierce the muscular mass, on the back of the sacrum, to ra- mify in the skin over the sacrum and nates. CERVICAL PLEXUS. 203 Anterior Branches of the Spinal Nerves. CERVICAL PLEXUS ; formed by the ant. branches of the first (not sub-occipital,) second, third, and fourth cervical nerves. The first and second at their exit from the vertebral foramina anas, by an ascending and descending branch, so as to form a curious loop around the transverse process of the atlas; from this loop branches supply the recti muscles and anastomose with the first cervical ganglion and the spinal acces- sory. The cervical plexus is situated under the post, edge of the sterno-mastoid muscle, between the rec- tus anticus and ins. of thesplenius colli ; it is covered by adipose tissue and lymphatic glands. Ram. Ascending set. 1, Superficial branches ; two or three ascend over the sterno-mastoid to the integuments; ram. superficial, colli, to the integuments over the ear and parotid gland ; a filament anastomoses with the seventh pair. 2, Deep branches ; three or four small nerves to the sterno-mastoid, digastric, sple- nius, &c. Descending set. 1, Internal branches; a. an anas- tomosing branch, to join the descendens noni; b. phrenic nerve; composed of branches of the second, third, and fourth cervical nerves ; it descends diagonally across the ant. scalenus, enters the chest between the subclavian artery and vein, descends between the pericardium and pleura accompanied by an ar- tery, (the left nerve winding around the apex of the heart,) to the diaphragm, on which it ramifies: it communicates with the last cervical ganglion. 2, External branches: a. supra clavicular ; b. supra acro- mial; and c. sternal, to the integuments covering those bones; external respiratory (Bell,) one of the several deeper-seated descending branches, which , descends on the side of the thorax to the serratus magnus muscle. Posterior set. a. A branch to anastomose with the 204 BRACHIAL PLEXUS. spinal accessory; b. branches to the trapezius, le- yator scapulae, and rhomboidei. BRACHIAL PLEXUS: composed of the anterior branches of the four last cervical and the first dorsal of the spinal nerves ; these branches descend paral- lel with each other, between the scaleni muscles, and only constitute a plexus in the middle of the axilia behind the tendon of the pectoralis minor. Collateral branches, 4, a. infra clavicular, branches to the subclavius, levator scapulae, and rhomboidei ; b. supra scapular nerve, passes through the supra sca- pular notch, to the supra and infra spinati muscles ; c. sub-scapular nerves, two or three branches, which sometimes come from the circumflex to the sub-sca- pularis m. d. thnracicse, four or five in number, de- scend behind and before the clavicle, to the surface of the pectoral muscles, b Terminal branches, 6 in number. 1. Circumflex, turns backwards under thelower edge of the sub-scapular muscle, and winds round the sur- gical neck of the humerus with the inferior circum- flex art., to terminate in the deltoid; it supplies the teres major et minor, latissimus dorsi, and skin over the shoulder. 2. Internal cutaneous, descends on the inner side of the arm, pierces on the fascia a little above the elbow, divides into filaments, which generally accompany the veins, and ramify in the skin nearly as far as the wrist. 3. External cutaneous, (perforans casserii,) pierces the coraco-brachialis m., descends on the outer side of the arm, pierces the fascia a little above the elbow, descends beneath the skin, to which it is distributed by separate filaments as far as the anterior and pos- terior part of the carpus ; it also supplies the mus- cles along which it passes ; hence its name. 4. Ulnar nerve, descends, on the short head of the triceps, passes between the internal condyle and ole- MUSCULO-SPINAL NERVE. 205 cranon, through the space between the two heads of the flexor carpi ulnaris, soon gains the inner side of the ulnar artery, which it attends to the hand : it terminates in, a, a superficial branch, which supplies the two sides of the little, and the ulnar side of the ring finger; and, b, a deep branch, which forms an arch by inclining outwards, beneath the flexor ten- dons, so as to supply the interossei, and terminate in the adductor pollicis ; c, dorsalis carpi ulnaris, turns over the ulna beneath the flexor ulnaris, to supply both dorsal edges of the little, and the ulnar edge of the ring finger. 5. Median nerve, (the largest branch, ) arises by two heads, which embrace the axillary artery : it descends 1st, on the outer side of the brachial artery, along the outer edge of the coraco-brachialis muscle; 2d, it crosses the artery to lie on its inner side, resting on thebrachialis anticus; 3d, it passes between the two heads of the pronator teres, and descends between the flexor sublimis and the flex, profund., between the tendons of which two muscles it enters the palm of the hand, where it divides into five digital branches. a, The thretf-ftrst correspond to the two edges of the thumb and radial edge of the fore finger ; b, the two last supply both edges of the index, and middle, and the radial edge of the ring finger: c, interosseous an- ticus; attends the anterior interosseous artery, with which it is lost on the back of the carpus ; d, palmar cutaneous, to the- skin on the palm of the hand. 6. Musculo spiral: runs with the superior profunda artery in the spiral groove of the humerus, and lies with that vessel between the brachialis anticus and supinator longus, where it divides into : a, r. radialis, soon gains the outer side of the radial artery, along which it descends to within a short distance of the wrist ; it now turns over the outer edge of the radius, its terminal branches supplying the two dorsal edges of the thumb, index, and middle fingers, and the radial 18 206 INTERCOSTAL NERVES. edge of the ring. (The dorsal and palmar edges of the little, and the ulnar edge of the ring finger, are thus supplied by the ulnar nerve; the dorsal and palmar edges of the thumb and other fingers, with the radial edge of the ring finger, by the median and radial branch of the musculo spiral,) b, ramus pro- fundus (post, interosseous,) pierces the supinator brevis, descends with the post, interosseus artery, and supplies the two layers of extensor muscles. Each principal artery of the arm has thus its attendant nerve. The skin of the upper arm is supplied, 1, by branches from the three upper intercostals, (cutaneous of Wris- bera,) which traverses the axilla; and, 2, by branches from the circumflex and spiral nerves. Anterior branches of the dorsal Nerves* A, INTERCOSTAL NERVES, 12 in no., extend from the first dorsal intervertebral foramen to that between the last dorsal and first lumbar. As a general rule, they gain the corresponding intercostal spaces, where they run (below the art.,) between the intercostal muscles, and divide, about midway between the spine and sternum, into external, or cutaneous branches, and proper intercostal branches or continuations of the nerve : the latter pierce the thorax, near the sternum, to supply the inner part of the pectoral muscles; the former having pierced the chest at the point above- mentioned, send anterior cutaneous branches, which run a regular parallel course, and post, cutaneous branches, which run over the ext. surface of the latis- simus dorsi. The intercostal nerves communicate close to the vertebrae by ascending and descending branches, and send one or two filaments to the cor- responding sympathetic ganglia. The first dorsal nerve belongs to the brachial plexus, and sends therefore but a small intercostal branch. The second intercostal is very tortuous before it INGUINO-CUTANEOUS NERVE. 207 reaches the space; the cutaneous branches of the se- cond and third are the cutaneous of Wrisberg. The fourth, fifth, sixth, and seventh dorsal intercostals follow the general rule ; but the eighth, ninth, tenth, and eleventh nerves traverse the costal attachments of the diaphragm to terminate on the abdomen, by cutaneous and muscular filaments, which, in rami- fying on the abdominal muscles, precisely follow the above rule. The twelfth intercostal sends a muscu- lar branch to the abdominal muscles as above, but its cutaneous branch is large, and descends nearly to the side of the ilium; it also sends a branch, which, with the ant. branches of the four first lum- bar nerves, constitute the lumbar plexus. THE LUMBAR PLEXUS, besides the above nerves, receives a branch from the last lumbar, to make up the uninterrupted chain of connection which includes all the spinal nerves ; it is situated on the second, third, and fourth lumbar transverse processes, covered by, or even partially buried in, the psoas muscle. Collateral branches, 4 in No. 1. Sup. abdominal branch (ilio-scrotal) arises from the first lumbar nerve, perforates the psoas, crosses the quadratus, runs round the abdomen parallel to the last dorsal branch (which it much resembles,) and at the iliac crista gets between the trans, and int. oblique m., where it divides into an abdominal and pubic branch; the former is distributed to the muscles like the last dorsal; the latter, sometimes joined by the next branch, runs along the cord with which it escapes to terminate in the skin of the labia or scrotum. 2. Inf. abdominal branch (ileo-scrotal minor} crosses the quadratus and iliacus m., running parallel to, but below, the former, which it sometimes joins; when it does not, it is seen as a second branch, making its way through some part of the inguinal region, to the same parts as the former. 3. Ing uino- cutaneous (external cutaneous.) Arises 208 ANTERIOR CRURAL NERVES. from the second and third lumbar nerve, traverses the psoas, crosses the iliacus below the last nerve, and escapes between the two ant. iliac spinous pro- cesses. Ram. a, anterior or femoral pierces the fas- cia, sends a cutaneous branch to the ant. and outer parts of the thigh down to the knee ; b, posterior to the skin, over the tensor vaginae, glutei, &c. 4. Genito-crural (external pudic.) Arises from the second lumbar nerve, traverses the psoas muscle, descends on its ant. surface, with the ext. iliac art., and just before it reaches the groin divides into two branches, a, internal or scrotal branch, crosses the artery, enters the inner ring, runs beneath the cord, and terminates, like the ilio-scrotal, in the la- bia or scrotum; b, a cutaneous branch, which termi- nates on the ant. and inner part of the thigh. Terminal Branches 2 in No. 1. Obturator ; arises from the third and fourth lum- bar nerves, runs beneath the inner margin of the psoas m. along the brim of the pelvis, escapes with the ob- turator artery through the obt. foramen, and in a space between the obturator ext. and pectineus m. divides into an anterior branch, which goes to the add. brevis et longus and gracilis, and a posterior branch to the obt. ext., and. brevis, and magnus. 2. Ant. crural nerves ; arises from the second, third, and fourth lumbar nerves, descends along the outer edge of the psoas m., between it and the iliacus inter- nus, and immediatelybelowPoupart's ligament divides into 1, a superficial set of branches, usually two in no., which supply the skin on the fore and inner part of the thigh, as far as the knee; 2, a deep set, of these, a branch (n. saphenus major) runs in the sheath of the femoral vessels, becomes subcutaneous just below the knee, and accompanies the int. saphena vein to ramify on the inner part of the dorsuin of the foot, thesaph. mm. runs along the sartorius. Numerous branches, GREAT SCIATIC NERVE. 209 divided into external and internal, supplies the mus- cles on the ant. and outer part of the thigh. SACRAL PLEXUS, the communicating branch of the last lumbar, and the ant. branches of the four first sacral nerves, unite into a large flat cord, which is situated deeply in the posterior part of the pelvis, on the pyriformis muscle: it is covered by the int. iliac artery, and (on the left side) by the rectus. Collateral Branches, 4 in No.. 1. Hs&morrhoidal, lower part of the rectum, sphinc- ter, and mucous membrane. 2. Vaginal, uterine, and vesical filaments, to those organs. 8. Pudic nerve, it exactly follows the course of the int. pudic artery ; Ram. a, a branch, which pierces the great sacro sciatic ligament, and winds round the tuber ischii to be distributed by branches cor- responding to the inf. hsemor. and superf. perineal art., to the skin about the perineum and scrotum; b, ramus dorsalis penis, to the skin of the penis in the male, clitoris in the female. 4. Smaller sciatic nerve, it escapes from the pelvis at the lower edge of the pyriformis m. Ram. a, muscular, distributed in all directions to the gluteus maximus; b, cutaneous, to the skin over the flexor muscles as far as the knee, by distinct post, and int. cutaneous br. Terminal Branch. Great sciatic nerve; escapes at the lower border of the pyriformis muscle, and descends between the tuber ischii and great trochanter to the middle of the thigh, where it terminates in two branches, the post, tibial and peroneal m. ; it rests upon the ex- ternal rotator and adduct. m., covered by the glu- teus maximus and hamstring muscles. Ram. a, branches to the obturator int., gemelli, glutens max., 18* 210 EXTERNAL SAPHENUS NERVE. ext. rotator, and adductor muscles ; b, a posterior, middle, and external cutaneous branch. Peroneal nerve (external terminal branch,) de- scends along the tendon of the biceps muscle, winds round the neck of the fibula, between that tendon and the external head of the gastrocnemius, where it is subcutaneous, and between that bone and peroneus longus m. it divides into three terminal branches. 1. Two recurrent branches, which supply the upper part of the extensor muscles, like the tibial recur- rent artery. 2. Musculo-cutaneous, descends in the course of the peroneal trunk, in the substance of the peroneus longus m., pierces the fascia some way above the ankle-joint, and divides into two branches, one, (in- ternal) ramifies, by two digital branches, on the in- ner border of the foot, and first and second toes: the other (external,) by jneans of three digital branches, which correspond to the digital spaces, ramifies on the outer border of the foot, and dorsal surfaces of the three last toes. 3. Ant. tibial, runs beneath the upper part of the common extensor m. to the interosseous ligament, descends along the ant. surface of the corresponding artery, runs beneath the annular ligament of the ankle, in the sheath of the ext. prop, pollicis, and di- vides into a branch, (deep digital,) which runs under the dorsal artery to supply the adjoining edges of the first and second toes; and one, which, after send- ing delicate filaments to the interosseous spaces, ter- minates in the extensor brevis digitorum m. The collateral branches of the peroneal nerve, are, 1, communicans peronei, which arises in the popliteal space, pierces the fascia, and unites with the commu- nicans tibice, to form the ext. saphenus nerve, under which name it descends with the vein to the outer side of the ankle, and sometimes to the outer side of the foot; its branches are calcanian and malleolar; "2, a OLFACTORY NERVE. 211 cutaneous branch to the skin over the outer and back part of the fibula, Post, tibial nerve, (intern, terminal branch,) de- scends, as the popliteal nerve on the outer back par* of the pop. vein, and, as the post, tibial nerve, along the back part of that artery, to the internal annular ligament, under which they are both included in one fibrous sheath. Collateral branches. 1, Muscular; 2, communicans tibise, unites with the communic. peronei as before described; 3, branches to the gastrocnemii and soleus. The terminal branches are, 1, inter nal plantar nerve, (the larger,) enters the sole of the foot, close to the calcaneum and above the flexor mus cles, and gives off four digital branches, which supply, as the median nerve did in the hand, both edges of the three first toes, and the inner edge of the fourth ; 2, External plantar nerve, (smaller,) runs outwards between the flexor accessorius and flexor brevis; it gives off, a, a deep branch, which enters the sole of the foot to sup- ply some of the muscles ; and b, three branches, one of which runs to the outer edge of the foot, the other two (digital) supplying both the edges of the little toe, and the outer edge of the fourth toe. A small branch also anas, with the last digital branch of the internal plantar n. The fifth and sixth sacral nerves, which do not enter into the formation of the sacral plexus, are ex- tremely small ; the latter is merely a delicate filament scarcely observable. The fifth anas, above, with the fourth, and, below, with the sixth; the latter pierces the sacro-sciatic ligament to terminate by three cu- taneous branches upon the coccyx. CEREBRAL NERVES, 9 PAIRS. 1. OLFACTORY, Or. by numerous filam. from the under surface of the olf. lobes ; term, roof of the nares septum and two sup. turbin. bones. The lobes are 212 INFERIOR MAXILLARY NERVE. attached to the brain by a pedicle, which sends, 1, a middle gray root through the subs. perf. to the soft com.; 2, an ext. long root, to the post, edge of fiss. Sylvii: 3, an int. short root, to the inner part of the ant. lobe. 2. OPTIC, Or. optic commiss. term, retina. To form the comm., 1, the inner fibres of the opt. fascic.meet transversely; 2, the mid. fib. decussate; 3, the outer fibres proceed without decussating. 3. MOTORES OCULI, Or. by a linear series of stria?, from the adjoining edges of the fascic. innom. at the ant. edge of the pons; term, in the orbit by 1, ram. super, to lev. palp, and sup. rectus; 2, ram. inf. (larger,) to rect. inf. et int. inf. obliq., radix ext. to ophth. gang. 4. PATHETICI (delicate long.) Or. valve of Yieus- sens; term, sub, obliq. joined to the opthal. nerve. 5. TRIGEMINI, (spinal nerve, double)both roots are attached to the side of the pons; traced, the sensy. to post, half of the medulla obi.; the motor to ant, pyram. within the pons. The semilunar sensy. gang. ?Gasserian,) rests on the petrous bone, and gives off, 1, ram. opthalm.; 2, rani. sup. max.; 3, R, inf. max. OPHTHALMIC. Ram. a. lacrymal; 1, fil. malar; 2, 'fil. palp., to palp, and conjunc.; 3, fil. lacrymal, to the gland, anas, with the fascial and s. max. n. b. frontal; fil. 1, supra orbitar; '2,supratrochlear. c. nasal; l,long root of lent, gang. 2, fil. infratrochlear.; 3, ethm. ant.; enters the skull, and descends through the crib, plate, sends a fil. to the septum, and one to the skin of ala nasi: 4, two fil. ciliar. SUP. MAXILLARY, ram. a, orbitar, 1, fil. lacrymal, 2. temp, malar; \),post. dental, 1, fil. post, et ant., to post, teeth, gums, and bucci- nator; c, ant. dental, antrum, and ant, teeth; d, infra orbitar (terminal.) INF. MAXILLARY, joined by the motor root ram. a, muscular, (motor root,) fils. deep temp., masseteric, buccal, pterygoid; b. auricular, (superf. temp.) anas, with the fascial; c, gustatory or VAGUS NERVE. 213 lingual, to papil. edge and tip of tongue, anas, with 1, chorda tymp., 2, infra dental; d, infra dental, fils., mylo-hyoicl, mental. 6. ABDUCENTES, Or. ant. pyramids at the post, edge of the pons ; term. ext. rectus m. ; anas, with ophthal- mic n. and 1st cerv. gang. ~ ( AUDITORY, portio mollis, \ attached. Or. fossa \ FACIAL, portio dura] between the corp. restif. and pons; traced the former round the c. restif, to the strise of the calamus in the 4th vent., the latter, through those bodies to the stem. PORTIO MOLLIS ; term, by, a, ram. to the cochlea, b, ram. to the vesti- bule and semicirc. canals. Anas, with port. dura. PORTIO DURA. Ram. In the fal. canal; 1, receives the Vidian, 2, gives off chorda tympani, which crosses the tymp. and joins the gust, nerve; 3, receives a filam, through the bone, from the vagus (Arnold.) Out of the ear. Ram. collateral; 1, post, auric, 2, styloid, 3, submastoid. Ram. term. ; 1, cervico -facial r. buccal, mental, cervical; 2, temp, facial; anas, with fifth pair; r. temp, orbitar, and infra arbitar. j" GLOSSO PHARYNGEAL, 1 Or. The two former 8. J PNEUMOGASTRIC, [-by a linear series of ( SPINAL ACCESSORY, ) fil. from the corp. res- tiform. ; the latter, also by a series of fil., from the lat. tract of the cord, extending in a line behind the lig. dentic. from the vagus to the fifth cervical nerve. The three escape by the foramen lacerum, the former in a fibr. canal distinct from that of the two latter. GLOSSO PHARYNGEAL. In the canal it presents a gan- glion, the br. of which are; &,fil. (Jacobson) penet. the inner wall of the tymp. ,and gives, 1, fil. to the carot. plexus, 2, fil. to anas, with Vidian, 3, fil. to the otic. gang. ; b, anas. fil. to facial nerve. In the neck; a, anas.jils., to vagus, and spinal access. ; b, r, digast. et stylo-hyoid; c, pharyngeal, to the plexus; d, tonsil- lary ; e. Lingual (term.,) papil., and muc. mem. at the root of the tongue. VAGUS. In its canal ; a 214 SYMPATHETIC NERVE. ganglion, ram. a, fil. penet. the jugul. foss. to anas, with the facial in its acqueduct, it first sends a fil. to r. Jacobson. At its exit; anas, fil., to spinal access., hypoglossal, pharyngeal, and sup. cerv. gang. In the neck; a, r. pharyn. to plexus; b, sup. laryngeal, to epiglottis, crico-thyroid muscle; c, r. to join the cardiac n. In the thorax : the right vagus enters be- tween the subc. art. and vein ; the left, behind the subc. vein, in a triang. interv. between the com. carot. and sub. art. Ram. a, n. recurrens, the left round the aortic arch, the right round sub. art.; 1, fils. to join the cardiac nerves and plexus, 2, fil. oesoph., and tra- cheal, 3, pharyngeal, 4, term, laryngeal muscles, and muc. memb. ; b, ant.pulm. brs.; and c, post, pulm. brs. to the pulmon. plexuses; d, cesophageal plexus, sur- round the organ; e, gastric plexus, the left vagus ant., the right poster., the latter joins the solar plexus. SPINAL ACCESSORY; sometimes forms the post, root of the first cerv. pair. In the canal, it is joined to the vagus. At its exit; a, anas. fil. to glos. -pharyn., vagus, and three upper cerv. nerves; b, r. sterno mastoid, which m. it perf. to term, in the trapezius. 9. HYPOGLOSSAL; Or. by a linear series of fil. like the ant. roots of the spinal nerves, between the c. oiiv. et ant. pyram. : it trav. the ant. condyl. for. Ram. collat.; a, anas fils., to vagus, sub. cerv. gang., first and second cerv. nerves, and ling, nerve ; Ram. term.; a, r. to the glossal muscles; b, r. descend, noni, anas, with cerv. plexus, and sends fil. to the infra hyoid muscles. SYMPATHETIC SYSTEM. The muscular tissue of the heart and digestive canal, the genital and urinary passages, the arteries, espe- cially those of the trunk, are supplied by this system; brs. are also sent to the organs of sense. The veins, lymphatic vessels, and glands, and serous membranes, receive none from it. The system consists of, 1, the SPLANCHNIC NERVES. 215 ganglia of the sympathetic ; 2, detached ganglia in the head, chest, and abdomen; 3, nervous plexuses, derived from them. The ganglia, although they derive their energy solely from the cerebro-spinal system, are, to a certain extent, independent sources of nervous power, which, by means of their plexuses, is developed in such combinations as are suited to the associated functions they are designed to regulate. The SYMPATHETIC NERVE consists of three cervical, twelve dorsal, four lumbar, and four sacral ganglia, extending in a chain from the first cerv. to the last sac. vert, and connected by a nervous cord. They commun. by 1, Ext. br., one in the cervical, two in the other regions with the several spinal pairs ; 2, by Ascend, and Descend, br. with the gang, next above and below; 3, they send Intern, br. principally to attend the arteries; and 4, a Visceral, or splanchnic set. ARTERIAL BR., a, Nervimolles; from the first cerv. gang., to accomp. the ext. carot., and its br. formingplexus, named from them, as thyroid, lingual, meningeal, &c.; b, Nerv. vertebralis, from the last cerv. gang, accomp. the vert. art. and its br. (The int. carot. andbr. are supplied by the cavern, plexus;) c. fil. to the subt. are. and its prim. br. and to the brach. plex.; d, Aortic fil. from the dorsal gang, to accomp. each interc. art.; e, Lumbar Aortic br .The remaining vessels in the neck, thorax and abdomen, are attended by fil. from the vagus, cardiac gang, and semil. gang. VISCERAL. FIL. a, Pharynaeal, to the plexus; b, Laryngeal, joins the sup. laryng. n.; c, Cardiac nerves, three on the right, sometimes but two on the left ; arise from the three cerv. ganglia, and descend in the thorax, where they are joined by card, br. of the vagus and the recur, n.; term, in the card, gang, and plexus; d, Splanchnic nerves, two in number; the sup. from sixth, seventh, eighth, and tenth thoracic gang.; the inf. from the eleventh and twelfth gang. The former joins the semilunar gang., the latter- the 216 PULMONARY PLEXUSES. renal plexus ; e, splanchnic br. from the lumbar gang, to the lumbar aortic, and inf. mesent. plexus. CEREBRAL GANGLIA, a, Lentic. Gang. sit. between the ext. rectus and opt. n.; Post, br.; 1, fil. or long root, from the nasal n.; 2, a fil. short root, from inf. br. of the third pr.; 3, fil. to the caver, plex. Ant. br.; sup. and inf. ciliary fil. (two oil. br. come from the nasal.) b, Meeker s Gang.; sit. pteryg.-max fissure; Post. br. 1, Vidian nerve; Int. br. 2; naso-pal. n.; Descending br. 3, post. pal. n.; 4. fil. to carot. plex.: 5, fil. to super, max. n. c, Otic Gang. (Arnold;) sit. inner side of inf. max. n. immediately below the for. oval. Ram. 1, long root, which is the middle fil. or Jacobson's n.; 2, short root, to the inf. max. n.; 3, fil. to lax. tymp. in. ; 4, fil. to auric, temp. n. CARDIAC GANG, and PLEXUS; sit. under the aortic arch, and between it and the trachea. Comp. cardiac nerves and card. br. of the vagus and recurrt. Ram.; fil. to form the ant. post, coron. plex. SEMILUNAR GANG, and solar plexus ; sit. on the coeliac axis: the ganglion on each side rec the grt. splan. n.; the plexus rec. br. from the sm. splan. n., and right vagus ; sometimes the right phrenic. The br. of the solar plexus accompany the neigh- bouring art. and branches, forming plexuses, which are named from them: the hepatic, splenic, and gas- tric plex., commun. with the vagus. The Sup. mesen- teric plex. also receives post. fil. from the lumbar gang. The Renal plex. rec. the lesser splanch. nerves, and forms the spermatic, or ovarian plexus. The Inf. mesent, plex. rec. fil. from the lumbar gang, and the hsemorr. plex. &c. The Hypogastric plexus is sit. on each side of the rectum; it is comp. of lumbar and sacral fil., and supplies the rectum, bladder, uterus, vagina and testicles. The Pharyngeal plexus is sit. on the side of the pharynx ; it is comp. of fil. from the vagus, glosso-ph. and sympathetic. The Pulmon. plexus, ant. (smaller) SYMPATHETIC NERVE. 217 and post, (larger,) are comp. principally of the va- gus ; it rec. br. from the sympath.; ram. to the bron- chial tubes. (Esophageal plexus, comp. principally of the right and left vagus. The Sup. cerv. gang, commun. with the cereb. nerves; 1, by a carot. fil., which forms the carot. plexus, and joins the cavernous plexus; it receives a fil. from the Vidian and Jacobson's n., and sends fil. to the sixth pr. of n. (The cavern, plex. rec. fil. from the third, fifth, and sixth prs. and Lent, gang.; sends fil. along the br. of the iiit. carotid.) 2, by fil., which commun. at the base of the skull, with the glosso-phar. vagus, hypoglossal, and facial nerves. The last sacral gang, is situated on the front of the lower extremity of the sacrum (impar.) branches from it descend to the anus. Although the sympathetic nerve is here described as proceeding from the spinal nerves, it may be more proper to regard it as a distinct nervous sys- tem, which communicates by filaments with the spi- nal and cerebral nerves. Its filaments preside over the functions of organic life, and act independently of the will. 19 218 CHAPTER IX. OF THE BONES, LIGAMENTS, AND JOINTS. The Bones of the Head are divided into those of the cranium and face. The cranial bones are eight in number, viz., one frontal, two parietal, one occipital, two temporal, one sphenoid, and one ethmoid. FRONTAL. Sit. upper and ant. part of skull. Ant. surface convex, is slightly depressed on the mesial line, indicating the union of the two pieces of which this bone consists in the young subject, on each side of this bone is convex, and covered superiorly by the scalp, inferiorly it is irregularly concave, and immediately beneath again convex, opposite the frontal sinus, laterally is a concavity forming part of the temporal fosste, bounded above by the tempo- ral ridge. Post, surface, concave, lodges the ant. lobes of the brain ; on the mesial line is a projecting spine, which divides as it passes upwards into two, leaving a depression: the former gives attachment to the falx cerebri, the latter lodges the commence- ment of the sup. longitudinal sinus. Inferior surface presents the orbital plate, this is concave beneath and forms the roof of the orbit in front, and to the outer side is a deep depression for the lachrymal gland, and internally a slight depres- sion for the pulley of the sup. oblique muse, irregu- larly convex above, it supports the ant. lobes of the brain. The circumference of the frontal bone presents a slight projection in the centre ; from this, passing out- wards, it forms the coronal suture with the parietal bone ; beneath this, it articulates with the ant. inf. angle of the parietal, and anteriorly terminates in th PARIETAL BONE. 219 ext. angular process which artic. with the malar bone, passing inwards from this are, the superciliary arch, notched near its inner ext. by the superciliary notch, sometimes a foramen, the int. angular process for artic. with the os nasi, and on the mesial line the nasal xpine, to support in front the nasal bones and poste- riorly artic. with the nasal lamella of the ethmoid ; the posterior edge of the orbital plate artic. posteriorly with the lesser wing of the sphenoid, internally with the orbital plate of the ethmoid, and more anteriorly with the os unguis. The foramina are nine, viz., with the ethmoid one foramen csecum, and four, two, anterior, and two posterior int. orbital ; two super- ciliary or supra-orbital, two frontal sinuses. It articulates with four bones of the cranium ; two parietal, sphenoid, and ethmoid, and eight bones of the face, nasal, sup. maxil. lachrymal, and malar. The frontal sinuses exist in the anterior and inner part, and extend backwards into the orbital plates. PARIETAL. Sit. Superior and lateral part of cra- nium. External surface convex, presents in centre parietal eminence ; below this a rough surface, a little flattened to form part of the temporal fossae above, and the squamous sutures with the temporal bone be- neath. Inner surface, irregularly concave, is marked by the convolutions of the brain, and anteriorly by the branches of the mid. meningeal art. Circumference. The upper edge forms with the opposite bone the sagittal suture, it is grooved internally for the sup. longitudinal sinus ; the anterior forms with the frontal the coronal suture; the posterior joins the occipital to form the lambdoid suture; the inferior, arched, is overlapped by the squamous portion of the temp v . bone forming the squamous suture. The ant. inf. angle, prolonged downwards to artic. with the sphenoid, is grooved internally by the middle art. of the dura mater; the post. inf. angle obtuse, joins the mastoid part of the temp., and is grooved by the lateral sinus. 220 OCCIPITAL BONE. The parietal artic. with five bones, frontal, sphenoid, temporal, occipital, and the opposite parietal. OCCIPITAL. Sit. post. inf. part of cranium. Ext. and post, surface irregularly convex, smooth above, is covered by the scalp ; it is separated from the inferior portion by the central protuberance, to which is at- tached the lig. nuchae, and on each side by the supe- rior transverse ridge, for the attachment of the occi- pito-froiitalis and trapezius muscle; beneath this, the bone forms a part of the base of the skull, it pre- sents a rough surface for the insertion of the com- plexus and splenius capitis, then the inferior trans- verse ridge and another rough surface for the inser- tion of the recti postici and sup. oblique; on the me- sial line is a rough spine for the attachment of the lig. nuchae ; more in front is the foramen magnum, oval in shape; it transmits the spinal marrow and its membranes, vertebral arteries, and spinal accessory nerves ; in front of this is the basilar process, which passes upwards and forwards, and joins the body of the sphenoid ; its superior surface, concave, receives the pons Yarolii ; the inferior, slightly convex, gives insertion to the recti cap. antic, muse, posteriorly, and anteriorly forms the roof of the pharynx. On the under and lateral ant. part of the foramen ni;i wards, the inferior forwards. Spinous process long and drooping. Spinal ca?ial 1 small and circular. Peculiar dorsal vertebrse. First, has one on each side a distinct facette for head of first rib, and a half one for that of second rib, resembles cervical. Tenth, eleventh, and twelfth, one facette for head of rib. INTERVERTEB&AL LIGAMENTS. 231 eleventh and twelfth no facette, on transverse pro- cess for tubercle of rib. Twelfth, inf. artic. process directed outwards. Lumbar vertebrse. Largest, oval, long axis trans- verse, flat above and below. Transverse processes long, thin, and horizontal. Artic. processes. Supe- rior, concave, directed inwards, inferior the reverse. Spinous processes, short, strong, and square, project posteriorly. Spinal canal large and triangular. Peculiar lumbar vertebra. Last. Transverse pro- cess short, inf. artic. process directed forwards. Body cut off obliquely to articulate with sacrum. Ligament of Spine. Occipito-atlantoidean artic. Anterior and posterior lig. Or. from edge of foramen mag. Ins. upper edge of atlas. Capsular surrounds artic. surfaces. Occipito- axoidean lig. Or. anterior and inner border of fora- men mag. Ins. posterior surface of body of axis; passes over artic. between first and second vertebrse. Artic. between atlas and odontoid process. Beneath preceding are the transverse and oblique or check liga- ments. Transverse, Or. a tubercle on each side of oblique process of atlas, passes across the back of odontoid process. Ins. opposite side of atlas. Check, Or. one on each side from near summit of odontoid process, passes upwards and outwards. Ins. inner edge of foramen magnum. Inter vertebral Ligaments. Anterior stretches from the front of the body of the second vertebra, along the anterior surface of the spinal column, down to the ex- tremity of the sacrum; it is expanded, and is attached most firrrly to the intervetebral substance. Poste- rior proceeds from the back part of the body of second vertebra, being here continuous with the occipito - axoidean lig. along the post, surface of the bodies of the vertebras, and is implanted inf eriorly into the upper bone of the sacrum; its edges are lunated arid well- 232 THE RIBS. defined ; it adheres most firmly to the inter, vert, sub- stances, opposite to which it expands, but loosely to the bodies of the vertebrae. Intervertebral substance, or fibro- cartilage. Between the bodies of the vertebrae (except first and second) to which it firmly adheres, deeper in the lumbar than dorsal, and in these than in the cervical regions, the fibres run obliquely, so as to decussate, and are ar- ranged in concentric laminae ; about the centre, but near the spinal canal, it forms a semi-pulpy substance, of a diamond shape. Ligamenta subftava extend in pairs, one on each side, from the lamina of the spinous process above to that below, from the axis to the sacrum, so as to close the spinal canal between the laminae. Supra spinous lig. extend from post, tubercle on the occipital bone to the sacrum, attached to the ex- tremity of each spinous process, its cervical portion forms the lig amentum ?iuchss. Inter, spinous lig. do not exist in the neck, are thin and weak in the back, but are strong in the lumbar region ; the fibres stretch from one spinous process to the other. Inter, transverse lig. A few irregular fibres, stretching, as their name implies, are only distinct in the lower dorsal and lumbar regions. The Ribs, twenty-four in number, are divided into seven true and five false. The former are connected to the sternum by means of the costal cartilages ; the latter are only indirectly connected thereto. Each rib consists of a head,neck,tubercle,and body. Head, slightly expanded, divides into two concave facettes, for articulation with the corresponding facettes on the vertebrae, separated by a ridge which gives attachment to the inter-articular lig. Neck pro- ceeds outward and backwards, slightly rounded, and THE STERNUM. 233 terminates in the tubercle, a small convex facette, which articulates with the transverse process of each vertebra, beyond which it is rough for the attachment of the posterior costo-transverse lig. Body, curved, convex outwards, concave internally, presents pos- teriorly an oblique line indicating the angle, of the rib, at which point the bone turns forward. The ridge affords attachment to the sacro-lumbalis ten- dons, the rest of the body is covered externally by muscles, internally it is lined by the pleura; its upper edge is thick and rounded, its lower edge slightly grooved for the intercostal vessels; both give attachment*to the intercost. muscles. Ant. extremity, slightly expanded, is concave, and receives the ex- tremity of the costal cartilage. The^rs^ rib is short and flat, and has no angle ; its upper surface is marked by two grooves for the sub- clavian vein and artery, separated by & ridge for the insertion of the scalenus antlcus muse.: the head has but one articulating surface for the first verte- bra. The tenth, eleventh, and twelfth ribs have but one artic. surface on their heads ; the eleventh and twelfth have neither angle nor tubercle; they are short and thin, pointed anteriorly, and loose, hence called floating ribs. The costal cartilages, twelve in number, resemble the ribs to which they are attached ; the first is short, those of the true ribs articulate with the ster- num, those of the false are joined together, and to the cart, of the last true rib, excepting the eleventh and twelfth, which are free. The Sternum is situated on the mesial line of the thorax, in front sloping downwards and forwards. Its anterior surface, irregularly flat, is covered by the skin and aponeurosis ; its post, surface, slightly concave, bounds the ant. mediastinum in front. The sternum is marked laterally by a deep articular surface above for the clavicle, and, beneath this, by 20* 234 BONES OF UPPER EXTREMITY. articular surfaces, concave, for the cartilages of the true ribs. It consists of two pieces, the superior short and triangular, the inferior long and quadrila- teral; to the lower extremity of this is connected the xiphoid cartilage. Ligaments of the Ribs. Anterior costo-vertebral, Btretches from the ant. surface of the head of each rib to be inserted by radiating fibres into the vertebra above and below, and the intervening intervertebral substance. Inter- articular runs from the ridge on the head of each riVto the adjoining inter-vertebral sub- stance. Posterior costo-tramverse lig. Or. extremity of transverse process. Ins. non-articular portion of tubercle. Middle costo-transverse lig. connects the back part of the rib to the front of the corresponding transverse process. Inferior costo-transverse, wanting in the first and last ribs, arise from the lower border of the transverse process, and is inserted into the crest on the upper edge of the rib beneath. The costal cartilages are connected to the sternum by irregular bands of fibres on the ant. and post, surface of this bone: the artlc. is lined by synovial membrane. THE BONES OF THE UPPER EXTREMITY consist of the clavicle, scapula, humerus, radius, and ulna, the carpal bones, metacarpus, and phalanges. Clavicle, extends from sternum, upwards and back- wards, to the acromion process, curved like an italic /, its ant. and post, surfaces are convex and concave in opposite directions. Sternal end, thick and trian- gular, artic. with the sternum. Body, nearly cylin- drical. Acromial end, flattened, and rests on the edge of the acromion process, by a small articulating sur- face; its ant. surface gives attachment to the pect. major and deltoid, its post, to the sterno-mastoid and trnpezius, its under surface to the subclavius. Ster no- clavicular Ligaments. Anterior andj^os^n'or, stretch from the inner ext. of the clavicle to the SCAPULA. 235 sternum. Inter-clavicular, extends from one clavicle to the other, behind and a little above the sternum. In the interior of the articulation is an inter-articular cartilage, lined by a double synovial membrane. Costo- coracoid, Or. cartilage of first rib passes up- wards and outwards, enclosing subclavian between two layers. Ins. under surface of clavicle and root of coracoid process. Acromio clavicular ligaments, superior and inferior, stretch from one bone to the other. SCAPULA, Sit. upper, lateral, and posterior part of thorax, extending from second to seventh rib. Int. or ant. surface concave and marked by several ridges, forms the subscapular fossa, and give attach- ment to the subscap. muscle. Ext. or post, surface is divided by the spine into the supra and infra-spi- natus fossae, muscle ; the latter convex, gives at- tachment to the infra-spinatus, at its lower edge to the teres minor. A quadrilateral flat surface over the angle gives attachment to the teres major. The spine commences from the posterior border near its upper third, passes upwards and forwards, and ter- minates in a quadrilateral flat process, the Acromion: to its upper margin is attached the trapezius, to its lower the deltoid. Superior margin, thin and short, is notched anteriorly by the supra-scapular notch, in front of which arises the coracoid process, which curves forwards and gives attachment to the coraco- brachialis and short head of biceps in front, and the pect. minor internally. Posterior margin, or base, slightly curved, gives insertion to the rhomboid muscles. Anterior margin, thick, gives origin to the long head of the triceps near the neck of the bone. The superior posterior angle gives insertion to the levator anguli scapulae; the anterior forms the glenoid cavity, supported on an elongated process, the neck. Glenoid cavity, oval, long axis directed 236 HUMERUS. vertically, is concave, to receive the head of the humerus. Ligaments of the Scapula. Sup. Proper Lig. crosses the supra scapular notch, and gives origin to the omo-hyoid muscle. Spino-glenoid stretches from the under-surface of the spine to the upper and posterior border of the glenoid cavity. Coraco-acromial arises broad from the coracoid process, passes upwards, and is inserted narrow into the acromion. HUMERUS, OR ARM-BONE. Head, rounded and con- vex, forms little more than half a sphere, is directed upwards and inwards, and joins the glenoid cavity to form the shoulder-joint: it is supported by the anatomical neck, forming a deep groove for the at- tachment of the capsular ligament: beyond this are the greater and lesser tuberosities, the former, the ex- ternal, has three facettes for the insertion of the supra-spinatus, infra-spinatus, and teres minor muscles. The latter, the internal, gives insertion to the subscapularis muse.; between them in front is the bicipital groove through which the long tendon of the biceps runs; beneath^them the bone contracts and forms the surgical neck. Body, or shaft, round above, is twisted in the middle, flat and triangular below, its posterior surface gives origin to the second and third head of the triceps, between which is a groove for the musculo-spiral nerve ; on the inner surface, near its centre, is a rough surface for the insertion of the coraco-brachialis, and on its outer a triangular rough surface for the insertion of the deltoid ; the anterior surface beneath this affords origin to the brachialis anticus muscle. The lower extremity of the humerus is flattened and twisted a little forwards. From within outwards are, the int. condyle, projecting, gives origin to the tendon of the pronators and flexors, and the int. lat. ligament; the epiirochlea, a projecting eminence, the trochlea, an articular surface for the greater sigmoid cavity of the ulna, bounded in front and behind by the ant. and THE ULNA. 237 post, humeral fossse; a slight projection, a rounded tsmall head, the capitulum, to artic. with the head of he radius, the ext. condyle, slightly projecting for *he origin of the ext. Lit. lig. and the supinators and extensors ; from each condyle a ridge of bones pass es upwards to the humerus, and affords attachmentto the intermuscular septa and some of the muscles of the fore-arm. THE SHOULDER-JOINT is formed by the glenoid cavity and head of the humerus just described. Ligaments, Capsulars, arises from neck of scapula, outside brim of glenoid cavity, descends expanding round the head of the humerus, and is inserted into the anatomical neck; strongest inferiorly, weak su- periorly, it is perforated in front by the long head of the biceps, internally by the subscapularis ten- don, and above by the supra-spinatus. Coraco-humeral, or accessory, extends obliquely downwards and outwards from the coracoid process to the ant. part of the great tuberosity. Glenoid sur- rounds the brim of the glenoid cavity and is continu- ous with the tendon of the biceps. BONES OF FORE-ARM. Ulna forms the inner bone. Sup. ext. present greater sigmoid notch to artic. with the trochlea of the humerus, bounded above by the olecranon process, to which the tendon of the triceps is attached, in front by the cor onoid process for the insertion of the bran- chialis anticus; on its outer edge is the lesser sigmoid notch for artic. with the side of the head of the ra- dius. Body, triangular is divided into three sur- faces by three lines, affording attachment to the muscles and intermuscular septa. Lower ext. first contracted, then expands and forms a rounded ex- tremity, to artic. with the concavity on the radius, 238 ELBOW-JOINT. on its inner part is the styloid process to which the int. lat. lig. of the wrist is attached. Radius lies on the outer side of the fore-arm ; sup. ext. forms the head, on which is a cup-like cavity to artic. with the capitulum of the humerus; on its side an artic. surface for the lesser sigmoid notch of the ulna; below this is the neck and at its lower and inner part the tubercle into which the tendon of the biceps is inserted. Body, is divided into three sur- faces, by three lines for the attachment of muscles and fascia, its ext. surface convex presents near its centre a rough surface for the insertion of the pro- nator teres. Inf. ext. expanded and quadrilateral presents in front a concavity for the insertion of the pronator quadratus, posteriorly it is marked by three grooves for the passage of the extensor tendons, the middle groove lodges the extensor secundi internodii pollicis tendon; the second, to the ulna side of this, transmits the extensor com. and indicator tendons: the third to the radial side of the first is divided into two for the tendons of the extensores carpi ra- dialis. Along the ext. border is another groove di- vided into two for the extens. ossis metacarpi and primus internodii pollicis tendons; externally is the styloid process, to which the ext. lat. lig. of the wrist is attached, and on its outer surface the tendon of the sup. longus; internally a concave surface to artic. with the ulna inferiorly, is the artic. surface for the carpus divided partially into two by a slight ridge. THE ELBOW-JOINT is formed by the lower ext. of the humerus and upper extremities of the ulna and radius as just described. Ligaments. Anterior, Or. anterior surface of humerua around ant. humeral fossa, descends obliquely in front of the joint. Ins. annular lig. of radius and coronoid process. Post. lig. not so well marked. Or. around post-humeral fossa. Ins. ext. of olecranon process. Int. lat. flat and triangular. Or. int. condyle of THE CARPUS. 239 humerus. Ins. side of the olecranon and coronoid process. Ext. lateral, Or. ext. condyle of humerus. Ins. side of annular lig. of radius. Superior Radio- Ulnar Artie, formed by the side of the head of radius and lesser sigmoid cavity of ulna. Ligaments. Annular Or. from front and back of lesser sigmoid cavity of ulna, surrounds the edge of the head of the radius. Oblique lig. Or. root of co- ronoid process, descends obliquely outwards. Ins. side of radius below its tubercle. Inferior Radio- Ulnar Articulation, formed by con- vex side of lower ext. of ulna, and concavity on in- ner side of radius, the ligaments are anterior and posterior, composed of irregular fibres attached to each bone close to artic. surfaces. THE CARPUS consists of eight bones arranged in two rows. First row, from without inwards as follows, sca- phoid, lunar, cuneiform, and pisiform. Second row, trapezium, trapezoid, magnum, and unciform. Scaphoid. Largest of first row, convex above, con- cave beneath, presents four artic. surfaces, superior to artic. with the radius, internal to artic. with th