The Anterior Limb Skeleton. 



99 



three borders, one, the superior border (margo superior), is directed 

 toward the occiput; another, the vertebral border (margo vertebralis), 

 toward the v^ertebral column ; and the third or axillary border (margo 

 axillaris), toward the armpit. The corresponding angles are medial, 

 inferior, and lateral. The lateral surface bears a stout bony plate, the 

 scapular spine (spina scapulae), which arises from the body of the bone 

 through about two-thirds of its extent, and ends ventrally in a free pro- 

 jection, the acromion. The posterior margin of the acromion bears a 

 backwardly-directed process, the metacromion (processus hamatus). 

 Through the presence of the scapular spine, the lateral surface of the 

 bone is divided into two areas for muscular attachment. One of these, 

 the supraspinous fossa (fossa supraspinata), lies in front of the spine, 

 the other, the infraspinous fossa (fossa infraspinata), behind it. The 

 infraspinous fossa is the more extensive one. The medial surface, on 

 the other hand, presents a single large shallow depression, the sub- 

 scapular fossa (fossa subscapularis), which is triangular in shape and 



m-3- 



— mv. 



Fig. 37. Lateral surface of the left scapula: a., acromion; a.i.. a.l., and 

 a.m., inferior, lateral, and medial angles; e.g., glenoid cavity; c.s., neck 

 of the scapula; f.s. and f.i., supraspinous and infraspinous fossae: m., 

 metacromion; m.a., m.s., and m.v., axillary, superior, and vertebral borders; 

 p.c, coracoid process; s.s., scapular spine. 



occupies practically the entire surface. The apex or lateral angle of 

 the scapula, sometimes termed the head of the bone, is expanded to a 

 considerable extent in comparison with the slender portion — the so- 

 called neck of the scapula (collum scapulae) — connecting it with the 

 body of the bone. It bears a concave depression, the glenoid cavity 

 (cavitas glenoidalis), for articulation with the humerus. The articu- 

 lating surface is borne chiefly on that part of the bone corresi^onding to 

 the axillary border, but it also extends in an anterior direction to the 

 base of an overhanging projection, the coracoid process (processus 

 coracoideus). The free portion of the latter forms a blunt, hook-like 

 projection lying toward the medial surface of the bone. 



