THE BONES OF THE ANTERIOR LIMB 



199 



part of the thorax, with its apex directed downward and forward. 

 In the rabbit, as in quadruped mammals generally, the main 

 surfaces are respectively medial and lateral, and differ in this 

 respect from the human condition, in which, from the transverse 

 widening of the thorax, the corresponding surfaces are more nearly 

 ventral and dorsal. Of its three borders, one, the superior border 

 (margo superior), is directed toward the occiput; another, the 

 vertebral border (margo vertebralis), toward the vertebral column; 

 and the third or axillary border (margo axillaris), toward the arm- 

 pit. The corresponding angles are called medial (superior — 

 between the superior and vertebral borders), inferior, and lateral 



/n.v. 



Fig. 92. 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., meta- 

 cromion; m.a., m.s., and m.v., axillary, superior, and vertebral borders; p.c, 

 coracoid process; s.s., scapular spine. 



(glenoid — between the superior and axillary borders). 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 projection, the acromion. 

 The posterior margin of the acromion bears a backwardly-directed 

 process, the metacromion (processus hamatus). Through the pre- 

 sence 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 depress- 



