ELEMENTS OF MAMMALIAN ANATOMY. 



Extending proximad from the external condyle is the 

 supinator ridge. Proximad of the internal condyle is 



the supracondyloid foramen transmit- 

 ting the median nerve and brachial artery 

 (Figs. 72 and 89). The olecranon fossa 

 is the deep cavity on the caudal aspect 

 of the bone, opposite the coronoid fossa. 

 The articular surface of the distal ex- 

 tremity consists of the capitellum, for ar- 

 ticulation with the head of the radius, 

 and the trochlea, for articulation with the 

 sigmoid cavity of the ulna. On the 

 cephalic side of the proximal third of 

 the bone is the rough deltoid ridge for the 

 insertion of the deltoid muscle which 

 arises from the shoulder girdle. 



The ulna is the longest bone of the 

 forearm or antebrachium, and is caudad 

 of the radius. It articulates in the greater 

 sigmoid cavity with the trochlea of the 

 humerus and in the lesser sigmoid cavity 

 with the head of the radius. The distal 

 articulation is with the radius, cuneiform 

 and pisiform (Fig. 21). The olecranon 

 process forms the proximal termination 

 of the bone and serves for the insertion 

 of the triceps muscle. Distad of the sig- 

 -fnoid cavity is a projection known as the 

 coronoid process. The styloid process 

 forms a small projection on the distal 

 extremity of the bone. 



The radius is the preaxial or cephalic 

 bone of the antebrachium. It articulates proximally with 

 the capitellum of the humerus and the lesser sigmoid cavity 



or- 



J 



st 



FIG. 33. LATERAL 

 OR OUTER AS- 

 PECT OF THE 

 RIGHT ULNA. 



ar, Articular facet 

 for radius ; cr, 

 coronoid process ; 

 gs, greater sig- 

 moid cavity ; Is, 

 lesser sigmoid 

 cavity; on, olec- 

 ranon process ; 

 st, styloid pro- 

 cess. 



