OSTEOLOGY AND ARTHROLOGY 65 



directed inwards. This forms a kind of hook curved 

 towards the inside ; it represents the coracoid. process. 

 The scapula is surmounted by tlie cartilage of prolonga- 

 tion, of which the superior border, which is thin and curved, 

 is parallel to the superior border of the prominence of the 

 withers ; the cartilage forms, consequently, the lateral 

 surface of this region. The cartilage of prolongation 

 undergoes ossification in old horses. The humerus is short ; 

 the bicipital groove, situated on the anterior surface of the 

 superior extremity, separates the greater tuberosity from 

 the lesser, and is divided into two parts by a median ridge ; 

 it is this portion of the humerus which forms the prominence 

 known as the fioint of the shoulder, or point of the arm. The 

 deltoid impression well deserves the name of tuberosity 

 which has been given to it, for it is very prominent ; the 

 musculo-spiral groove is very deep. 



At the inferior extremity, the trochlea is large ; the 

 portion corresponding to the condyle of the humerus in 

 man is, in proportion to the latter, of small extent. The 

 olecranon fossa is deep. The epicondyle and the epitrochlea 

 are somewhat different from those of the human bone. In 

 the latter, the epitrochlea is salient towards the inner side, 

 causing an increased transverse diameter of the inferior 

 extremity of the humerus. In the horse — it is the same in 

 ruminants — this tuberosity projects backwards, folds on itself 

 in forming the internal boundary of the olecranon cavity, 

 and exceeds in diameter, in the antero-posterior direction, 

 the prominence of the epicondyle, which presents a nearly 

 similar arrangement. This latter has, however, a part 

 which, projecting externally, is situated at the inferior 

 part of a crest, that forms the posterior boundary of the 

 musculo-spiral groove. The result is that, contrary to the 

 condition found in the human being, the epicondyle is more 

 prominent transversely than the epitrochlea, but this latter 

 is more salient on the posterior aspect. The epitrochlea 

 and the epicondyle offer a larger surface for the origin of 

 muscles of the forearm than the same prominences in the 

 human bone do for the analogous muscles of the same 

 region. 



5 



