OCR Text |
Show 1867.] MYOLOGY OF IGUANA TUBERCULATA. 779 Fig. 8. Muscles of inside of right arm, the pectoralis and deltoid being cut short and reflected. B. Biceps. B.A. Brachialis anticus. C.B.I. First, or short, part of coracobrachialis. C.B.2. Second, or long, part of coraco-brachialis. D. 1. First part of deltoid. B. 2. Second part of deltoid. E. H. Epicoraco-humeral. I. S. Infraspinatus. P. Pectoralis. S. G. M. Sterno-cleido-mastoid. T. 3. Third, or external humeral, head of triceps, t. Tendinous fascia of origin of sterno-cleido-mastoid extending, between epicoraco-humeral and pectoralis, backwards to the true sternum. Subscapularis. This muscle is enormously developed, and is divisible into two parts (fig. 7, S. 1 and S. 2) :- (1) The first portion arises from the whole internal surface of the coracoid and epicoracoid, the spinous process of the scapula, and the membrane of each fenestra. The fibres converge, and towards its insertion this portion fuses with the second part. (2) The second portion arises from the lower part of tbe internal surface of the scapula and from the lower half of its posterior, or axillary, margin. It becomes tendinous towards its insertion, and, fusing with the first part, is attached to the ulnar tuberosity of the humerus and to the capsular ligament. This muscle is shown in fig. 2 (though its letter has been accidentally omitted), between D 2, S. Mg., T. 1, and the band binding down L. S. Lnternal sterno-coracoid (fig. 7, L. S. G). The specimen examined by m e had had the whole ventral surface of the body medianly divided from behind forwards, so that I cannot define the inner limit of this muscle. It arises, however, from the deep surface of the sternum, internal to the line of its junction with the coracoid and to the attachments of the ribs, and is inserted, by tendinous fibres, into the deep surface of the coracoid and lower part of the epicoracoid (*. e, to the deep surface of its lower spur), where it is contiguous to the inferior margin of the first portion of the subscapularis. External sterno-coracoid (fig. 7, E. S. Ci). This is a much smaller muscle than the preceding, which overlaps it when the inner surface of the scapular arch is looked at. It arises from the deep margin of that furrow (on the outer edge of the sternum) which receives the coracoid, and is inserted into the coracoid and epicoracoid, passing between those bones and the tendon of the internal sterno-coracoid. |