Refer constantly to the skeleton.
10. Then recognize the teres major ([p. 163], and [Fig. 75], d; [Fig. 77], c) and the common insertion of the teres major and latissimus ([Fig. 79], d′); find the bicipital arch ([Fig. 65], t′) and determine its composition ([p. 166]).
11 and 12. The serratus anterior and levator scapulæ ([Fig. 73], h and i, and [p. 122]). In order to expose the origin of these muscles, the external oblique muscle ([Fig. 68], p) must be recognized, and that part of it which has its origin from the fourth to the ninth rib should be transected about an inch and a half from its origin and reflected.
The thoracic portion of the rectus abdominis ([Fig. 73], k) and of the scalenus ([Fig. 73], f-f‴) should also be recognized and then raised at their outer borders and displaced toward the median line. No part of any of these muscles should be removed or cut except as directed.
The serratus anterior and levator scapulæ should be transected and reflected to get at their origin and insertion.
B. Muscles of the Arm
([p. 156]).—The arm is thus removed from the body and the dissection may be continued on the separated arm.
13. The clavobrachial ([Fig. 65], k, and [p. 157]). Its origin is best seen later. Dissect it up, but do not transect it.
Search now with great care for the coracobrachialis. Consult the figures ([Fig. 79], c) and descriptions ([p. 164]), and be especially careful not to injure the long head of the muscle and its tendon.
14. Dissect the coracobrachialis ([Fig. 77], f). Cut and reflect it.