SCAPULAR MUSCLES, &c.-BRACHIAL REGION.

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been already laid bare, and to dissect all the cut muscles, so as to bring their attachments completely into view; he may then remove the redundant masses which are no longer required, preserving only such portions of tendons and muscles as may be necessary for subsequent revision of their relations to the joints and their attachments to the bones. He will then clean the deltoid muscle, beginning from behind, so as to save as much as possible the cutaneous branches of the circumflex nerve (pp. 208 and 645). He will dissect the teres major muscle, and the quadrangular and triangular intervals which are separated by the long head of the triceps muscle, and lie between the teres muscle and the scapula; and he will lay bare, as far as can be done without injury to the muscles, the structures which pass through these intervals, viz., in the upper or quadrangular one, the circumflex nerve, with its branch to the teres minor muscle, and the posterior circumflex artery, and in the lower or triangular interval, the dorsal branch of the subscapular artery (p. 380). The deltoid muscle is next to be removed from the whole of its superior attachment, and beneath it will be seen the bursa that lies between the acromion and shoulder-joint (p. 138), and the branches of the circumflex vessels and nerve. The teres minor, infraspinatus and supraspinatus muscles are to be dissected and reflected, and the distribution of the suprascapular nerve and artery traced. While this is done, neither the deltoid ligament nor acromion need be divided. The subscapular muscle is likewise to be examined, with the two short subscapular nerves which supply it; and on reflecting this muscle, the subscapular bursa will be observed communicating with the shoulder-joint. In removing the muscles attached to the scapula, the student should bring into view the anastomoses of the posterior scapular, suprascapular, acromio-thoracic, dorsal branch of the subscapular, and the circumflex arteries. The scapular muscles may then be cut short at their attachments to the humerus.

4. Subcutaneous view of the Arm.-In proceeding with the dissection of the arm, if the part be in a condition favourable for the purpose, the dissector may at once display the cutaneous nerves and veins as far as the wrist (p. 647). He will, in that case, make an incision all the way down to the wrist in front of the limb; or, should it be deemed advisable not to remove the integument so far, he may terminate his incision half-way down the fore-arm. For the easier preservation of the cutaneous nerves, which lie close to the aponeurosis of the limb, he will remove the subcutaneous fat by reflecting it in the direction from above downwards. The intercostohumeral nerve is to be traced down to its distribution (p. 657). The nerve of Wrisberg and the internal cutaneous branch of the musculo-spiral nerve will be most easily traced from their deep origins (pp. 646 and 652). The internal cutaneous nerve will be found piercing the aponeurosis on the inside of the arm in two separate places, a few inches above the elbow; and on the outer side will be found the two external cutaneous branches of the musculo-spiral nerve, appearing in the line of the external intermuscular septum; while at the bend of the elbow, towards the outer side, the musculo-cutaneous or external cutaneous nerve will be observed emerging from the deep parts. Near the elbow, on the inner side, there is a small lymphatic gland, and on the subcutaneous part of the olecranon a small synovial bursa. Further down, there may be seen on the inner side a cutaneous branch from the ulnar nerve, below the middle of the forearm; on the outer side the radial nerve becoming superficial two or three inches above the wrist; and in front the palmar cutaneous branch of the

median nerve immediately above the annular ligament. On the fore-arm will be found the radial, median and ulnar veins; in front of the elbow the median-cephalic and median-basilic veins, together with the deep median branch; and in the upper arm the cephalic and basilic veins (p. 466).

5. Brachial Region more deeply.-The student will now remove the aponeurosis from the front of the arm. He will first dissect out the brachial artery with the venæ comites clinging to it and inter-communicating round it, and the median nerve crossing in front (p. 381). Arising from the inner side of the artery he will find the superior profunda branch turning back wards with the musculo-spiral nerve, a little farther down the inferior profunda branch accompanying the ulnar nerve, and a little above the elbow, the anastomotic resting on the brachialis anticus muscle : while from the outer side of the brachial artery a variety of muscular branches are observed to spring. The inferior profunda sometimes arises from the superior profunda branch. Not unfrequently two large arteries will be found in the arm, in consequence of a high division of the main trunk; the radial or ulnar artery, most frequently the former, being given off from the brachial at a higher point than usual, and sometimes even as high as the axillary artery. In some of these cases the artery which arises out of place lies superficially to the aponeurosis of the limb. The biceps and coraco-brachialis muscles are next to be dissected, and the deep part of the musculo-cutaneous nerve, which gives them branches (pp. 212 and 648). The dissector will be careful to preserve the aponeurotic slip of insertion of the biceps, which lies superficially to the vessels at the bend of the arm. The aponeurosis is to be removed from the back of the arm, and the intermuscular septa are to be examined (p. 230): the triceps muscle is to be dissected, and the superior profunda artery and musculospiral nerve are to be traced to its outer side (pp. 214 and 652). The musculo-spiral nerve is to be followed to its division into the radial and posterior interosseous trunks, and its branches, to the brachialis anticus, supinator longus and extensor carpi radialis longior displayed. The space in front of the elbow should next be dissected, so as to show the relations in it of the brachial, ulnar, and radial arteries, with the radial recurrent and anterior ulnar recurrent branches, and the median and radial nerves (pp. 389 and 397). The brachialis anticus muscle should also at this time be fully exposed down to its place of insertion.

6. Shoulder-joint, &c.-The articulations at the upper part of the arm ought now to be examined (p. 134). The conoid and trapezoid parts of the ligaments uniting the clavicle to the coracoid process are first to be dissected, and their uses studied; then the acromio-clavicular articulation, and the suprascapular and coraco-acromial ligaments of the scapula; lastly, the shoulder joint is to be dissected, the capsule is to be cleaned, the coraco-humeral ligament dissected, and the tendons of muscles in close relation with the joint examined. When lastly the capsule is opened, the origin of the long head of the noid ligament will be seen, and also membrane round the long head of the muscle.

biceps in connection with the glethe prolongations of the synovial biceps and beneath the subscapular

7. The Fore-arm in front.-Let the aponeurosis be removed from the front of the fore-arm, and let the five superficial muscles arising from the inner condyle of the humerus be dissected, beginning with the pronator radii teres; exhibiting its two heads of origin with the median nerve between

nerve.

THE FORE-ARM AND HAND.

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them, and proceeding successively to the flexor carpi radialis, palmaris longus (which, however, is often absent), flexor sublimis digitorum and flexor carpi ulnaris (p. 215); displaying the branches of the median nerve to the first four muscles, and that of the ulnar nerve to the last-mentioned muscle and to the flexor profundus digitorum (pp. 651 and 659). The course of the radial and ulnar arteries and nerves in the fore-arm is also to be studied, From the radial artery (p. 394) will be seen given off the radial recurrent, the muscular branches, the anterior carpal branch and the superficial volar; while arising from the ulnar artery (p. 388) will be seen the anterior and posterior ulnar recurrent, and the interosseous, dividing into anterior and posterior interosseous, and giving off the branch to accompany the median This last branch, the comes nervi mediani, derives importance from being not unfrequently developed as a third principal trunk of the fore arm, which passes down into the superficial palmar arch. The muscular branches of the ulnar artery, and its anterior and posterior carpal branches, are also to be exposed. The deep layer of muscles, consisting of the flexor longus pollicis, flexor profundus digitorum and pronator quadratus, are next to be dissected (p. 219); and along with them, lying on the interosseous membrane, and giving twigs to the muscles, the interosseous branch of the median nerve, and accompanying it, the anterior interosseous artery (p. 390). 8. The Hand in front.-For the dissection of the front of the hand, let an incision be made down the middle of the palm, a second transversely through the skin above the division of the fingers, and others down the middle of each finger. Let the palmar aponeurosis be exposed (p. 231), preserving the palmaris brevis muscle which is attached to its inner margin (p. 225); and let the skin be reflected from the front of the fingers and thumb, so as to exhibit the sheaths for the tendons, and the two digital branches of the artery and nerve on each (p. 218). The palmar aponeurosis is then to be removed, and the trunks of the ulnar and median nerves will be brought into view (pp. 649 and 651), as also the ulnar artery, the superficial volar branch of the radial artery, and the superficial palmar arch (p. 393). The short muscles of the thumb, viz., the abductor, opponens, flexor brevis, and adductor pollicis, are to be dissected, with the twigs of the median nerve supplying the three first, and the insertion of the flexor longus pollicis; then the abductor, opponens, and flexor minimi digiti, with the twigs of the ulnar nerve supplying them, and its deep branch piercing them (p. 225). The annular ligament is to be cleaned and the synovial sheath behind it examined; the tendons of the superficial and deep flexors are to be followed to their insertions, and the lumbricales muscles dissected. The deep branch of the ulnar artery may now be traced to the deep palmar arch, and that of the ulnar nerve to its distribution in all the interossei, two of the lumbricales, the adductor pollicis and the inner part of the flexor brevis pollicis muscle. The deep palmar arch and its branches are also to be fully examined (p. 400).

9. The Fore-arm and Hand Posteriorly. -For the dissection of the back of the fore-arm and hand let the remainder of the integument and aponeurosis be carefully reflected, and let the distribution of the ulnar and radial nerves to the dorsal aspects of the fingers be traced (p. 653). The muscles are then to be dissected in the following order, viz., the supinator longus, extensores carpi radiales longior and brevior, extensor carpi ulnaris, extensor communis digitorum and extensor minimi digiti, the extensor indicis, the three extensores pollicis, and, lastly, the anconeus and supinator brevis muscles (p. 220). There will be found passing through the fibres

of the last-mentioned muscle, the posterior interosseous nerve; and on the interosseous membrane the posterior interosseous artery, with its recurrent branch; they are both to be traced to their distribution (pp. 654 and 391). The lower part of the radial artery which has hitherto been hid from view may also now be studied: its posterior carpal and its metacarpal branch will be seen, together with the dorsal branches of the thumb and index finger (p. 398). The termination on the back of the wrist of the anterior interosseous artery after passing through the interosseous membrane is also to be noticed. Finally, the interossei muscles are to be dissected on both the palmar and dorsal aspects of the hand (p. 227).

10. Articulations of the Fore-arm and Hand.-The dissector may now return to an examination of the elbow-joint and other articulations of the upper limb. In connection with the elbow-joint, he will first make a revi sion of the relations of the soft parts to the joint, such as those of the triceps, brachialis anticus and supinator brevis muscles, the muscles attached to the outer and inner condyles of the humerus, and the median, musculospiral and ulnar nerves, together with the anastomoses of the superior and inferior profunda and the anastomotic branches of the brachial, with the two ulnar, the radial and the interosseous recurrent arteries. The dissector will then proceed to examine in detail the internal and external lateral ligaments, the anterior and the thin posterior ligaments, the orbicular ligament, the synovial membrane, and the cartilaginous surfaces of the bones (p. 138). The dissector should carefully observe the different kinds of motion of which the parts are capable, and the variations in the tightness of the ligaments and in the relations of external parts induced by these motions. In examining the lower radio-ulnar articulation, the dissector will particularly study the relations of the triangular fibro-cartilage, and the nature of the movements in pronation and supination of the hand; and, in the carpal joints, the extent of the synovial cavities and the position of the cartilage and interosseous ligaments.

III.-THORAX.

The right and left sides of this region constitute each a part. Its dissection may be completed within three weeks. It includes the deep dis section of the thoracic parietes, the viscera of the thoracic cavity, together with the upper surface of the diaphragm. It is indispensable that the dissectors of opposite sides should be present together and act in

concert.

1. Parietes and Pleura.-The dissection is to be commenced on the fifth day after the subject has been placed upon its back, that is, the tenth day after it has been first placed in the rooms. The external and internal intercostal muscles, and the intercostal arteries and nerves in the anterior part of their course, together with the parietal pleura, are to be first dissected (pp. 240, 402 and 655). Then let the internal mammary artery on the right side be laid bare by the removal of the 2nd, 3rd, 4th, 5th and 6th costal cartilages, in order that its relation to the sternum, and its anterior intercostal and perforating branches may be observed (p. 374). The corresponding costal cartilages on the left side may then be divided close to the ribs, and the ribs belonging to those cartilages on both sides are then to be divided as smoothly as possible about three inches beyond their angles; in doing which the dissectors must be careful to avoid injuring their hands upon the sharp spicula of the sawn extremities of the ribs. The anterior

PLEURE AND PERICARDIUM.

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limits of the pleural cavities and the position of the anterior mediastinum can now be examined, together with the position of the heart and great vessels in relation to the lungs and the walls of the thorax (p. 299). That this may be done more effectually, the lungs should be inflated through a tube introduced into the throat or wind-pipe, and their different positions and relations in the inflated and collapsed state attentively examined. The body of the sternum is next to be separated from the manubrium, and, together with the adherent costal cartilages of the left side, removed; and on the fragment of the thoracic wall thus separated the triangularis sterni muscle and its relation to the internal mammary artery may be further examined. The dissectors will then complete their examination of the anterior mediastinum, observing in its upper part the remains (if any) of the thymus body, and will carefully study the remaining reflections of the pleura. The heart within the pericardium is also to be observed (p. 313). In making this dissection the student may be required to separate the parietal from the pulmonary pleura, by breaking up with his fingers, or the handle of the knife, the inflammatory adhesions which are often met with. Great care must be taken to clean with a sponge and wash the interior of the chest and the surface of the lungs, first with water, and subsequently with preserving fluid (p. 892).

2. Parts External to the Pericardium.-The phrenic nerve will be seen on each side beneath the pleura in front of the root of the lung, and is to be dissected out; when its relation to the internal mammary artery, which it crosses at the upper part of the chest, and the branch of the latter artery which accompanies it, are to be observed (p. 640). The structures above the pericardium are then to be dissected. Foremost will be found the innominate veins and superior vena cava, with the termination of the vena azygos, and several smaller veins, viz., the inferior thyroid, internal mammary, superior intercostal, and bronchial veins (p. 453); and behind the veins, the innominate, left carotid, and left subclavian arteries arising from the arch of the aorta (pp. 340, 341 and 364). The pneumo-gastric nerves will also be found, that of the right side lying external to the innominate artery, and its recurrent branch turning round behind the subclavian artery; and that of the left side passing down in front of the arch of the aorta, with its recurrent branch winding behind the aorta (p. 618). Likewise crossing the arch of the aorta, on their way to the superficial cardiac plexus, will be found the cervical cardiac branch of the left pneumogastric nerve, and, usually, the superior cardiac branch from the sympathetic nerve on the left side (p. 690). The other cardiac nerves, viz., the cervical cardiac branch of the right pneumo-gastric nerve, the thoracic cardiac branches of both pneumo-gastric nerves, the three cardiac branches of the sympathetic chain of the right side, and the middle and inferior branches of the left side, are to be sought on the front and sides of the trachea, as they pass down to the deep cardiac plexus. The distribution of the pneumogastric nerves is then to be traced to the lungs and cesophagus; and, as far as possible, the posterior and anterior pulmonary plexuses are to be brought into view (p. 623). After that has been done, the roots of the lungs are to be fully dissected, the relations of the pulmonary arteries and veins and the bronchi observed, and the bronchial arteries traced to their origins (pp. 897 and 402).

3. Interior of the Pericardium and Heart.

The pericardium having

been examined on its outer aspect, is then to be cut open, and its interior carefully inspected (p. 300); after which it is to be removed, its remains