OCR Text |
Show 56 DR. B. C. A. WINDLE ON THE [Feb. 1, process of the atlas, and is inserted into the spine of the scapula acromion process as far as its apex. Pectoralis major consists of two layers folded in upon one another so as to present a rounded anterior border without any trace of division. The superficial portion arises from the clavicle and from the sternum as low down as the upper part of the xiphoid cartilage. This part is inserted (1) as usual, (2) into a common tendon with the deltoid. The deeper portion arises from the cartilages of the true ribs from the third to the last. This is inserted by two distinct slips, one of which passes to the tip of the acromion process, and the second to the fascia of the shoulder-joint and to the humerus external to the biceps, and as low down as to the upper edge of the attachment of the superficial portion. As has been above observed, there is no trace of the duplicity of these muscular sheets at the edge ; in fact it is only by dissecting carefully through the outer that the inner is reached. This inner sheet is obviously the pectoralis minor, and the condition present is one of extreme fusion of the two pectoral muscles ; or, perhaps better, of complete tucking-in of the p. major to form p. minor. Subclavius is strong and well-marked, a fact which corresponds with the comparatively small and freely movable clavicle. Sarratus magnus and levator anguli scapulae form a single undivided sheet. Latissimus dorsi sends down a fairly broad but very thin latissimo-condyloideus to the olecranon. Coraco-brachialis is inserted into the humerus (1) in the usual position ; (2) from this point as far down as the upper part of the internal condyle. The long head of the triceps is verv large and arises from rather more than one third of the axillary border of the scapula. Flexor profundus digitorum consists of two parts which unite under the annular ligament: the first arises from the internal condyle, the second from the radius, ulna, and interosseous ligament. There are three lumbricales, passing to minimus, annularis, and medius. Extensor communis digitorum sends a slip to each digit. Extensor indicis supplies that digit alone ; and extensor minimi digiti sends tendons to minimus and annularis. Pollex has one extensor. There is no supinator longus. Minimus has an abductor arising entirely from the pisiform, an opponens and a flexor brevis. The last arises from a small ossicle imbedded in the palmar fascia, slightly to the radial side of the centre of the palm and at its proximal portion. From this also arise the few fibres representing flexor brevis pollicis. This last diminutive digit has also on its outer side a few fibres representing abductor and opponens, and on its inner side an excessively rudimentary adductor. Minimus has an interosseous on its radial side; and each of the remaining digits has a pair lying in the same plane on its palmar surface. Abdominal Muscles.-At the upper part of the abdomen, the three usual lateral muscles are present and distinct; at the lower portion, as the fibres of the internal oblique and transversalis run parallel and are closely connected with one another, there can hardly be said to be any true differentiation between them. From the aponeurosis of the external oblique a sheet of fascia passes down upon the large funicular process of peritoneum containing the testicle. |