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the subclavius muscle. The clavicle is occasionally removed for sarcoma.

Fig. 69.—Left scapula, posterior surface (after Toldt).

The scapula or shoulder blade, so called from its shape, is a large, flat, triangular bone with a prominent ridge, the spine, crossing its dorsum or posterior surface near its upper edge. It extends from the second to the seventh rib, with its posterior margin parallel to and about one inch from the dorsal vertebræ. The head, in which is situated the glenoid cavity for articulation with the humerus or upper arm bone, is surrounded by a slight constriction, the neck. Above it projects the coracoid process, so called from its fancied resemblance to a crow's beak. This can usually be felt about one inch from the juncture of the outer and middle thirds of the clavicle and from it arise the short head of the biceps and the coraco-brachialis muscle. The acromion process at the end of the spine extends out beyond the glenoid cavity posteriorly and affords attachment to the del-