ENDOSKELETON AND VOLUNTARY MUSCLE 



67 



clavicle in front and the coracoid behind extend from the shoulder 

 medially and slightly ventrally to the epicoracoid cartilages in the 

 mid-line (Fig. 40). The glenoid fossa is a shallow cavity at the 

 junction of the scapula and coracoid, most of it being located on 

 the posterior side of the scapula. This cavity receives the head 

 of the humerus of the arm. The clavicle joins the scapula at the 

 acromium of the latter, directly in front of the glenoid fossa. 



The calcined edges of the epicoracoid cartilages, closely united 

 in the mid-line between the median ends of the clavicles and 



4Lm. 



Fig. 41. — Ventral view of pectoral girdle (A) and lateral view of left half of 

 pelvic girdle (B) of Rana catesbeiana. a, acetabulum; c, clavicle; co, coracoid; 

 G, glenoid fossa; h, humerus; i, ilium; is, ischium; o, omosternum; p, pubis; 

 s, scapula; 88, suprascapula; st, sternum; x, xiphisternum. The epicoracoid 

 cartilages make up the narrow region compressed between the median edges of 

 the coracoid bones. 



coracoids, represent the middle section of the sternum. The 

 remainder of the sternum is composed of the omosternum in front 

 and the sternum behind (Fig. 41). At the anterior end of the 

 omosternum is an expanded cartilaginous segment, the epister- 

 num. A somewhat larger cartilaginous disk strongly notched, 

 the xiphisternum, is attached to the posterior end of the sternum. 

 In man the sternum is of more importance in connection with 

 the ribs than with the pectoral girdle. The suprascapula is 

 absent and the coracoid is reduced to the coracoid process of the 

 scapula. The clavicle extends from the acromium of the scapula 

 to the anterior end of the sternum. The glenoid cavity is 

 located entirely on the scapula (Fig. 42). The human sternum 



