OSTEOLOGY AND ARTHROLOGY 



31 



surface of the inferior extremity, the olecranon fossa, is 

 very deep, more so than in the humerus of man. Its borders 

 being thus formed by the two processes, are very prominent. 

 In front we find the coronoid fossa, wliich is less deep than 

 that of which we have just spoken. 



There exists in some mammals an osseous canal, situated 

 above the epitrochlea, and known as the supratrochlear 

 canal (Fig. 19). It is bounded by a plate of bone which 

 at its middle portion is detached from the shaft of the 

 humerus, and blends with the latter at both its extremities. 



'L^.Ci 



Fig. 19. — Inferior Extremity of 

 THE Left Humerus of a Felide 

 (Lion). 



I , Epitrochlea ; 2, supra-epitrochlear 

 foramen. 



E5>.C. 



Fig. 20. — Inferior Extremity of 

 the Left Human Humerus, 

 showing the Presence of a 

 Supratrochlear Process. 



I , Epitrochlea ; 2, supra-epitrochlear 

 process. 



The brachial artery and median nerve pass through the 

 foramen. 



A similar condition is sometimes found, as an abnormality, 

 in man, which presents itself under the following aspect 

 (Fig. 20) : an osseous prominence more or less long, in the 

 shape of a crochet-needle — supra-epitrochlear process — 

 situated 5 or 6 centimetres above the epitrochlea ; the 

 summit of this process gives attachment to a fibrous band, 

 which is inserted by its other end into the epitrochlea and 

 the internal intermuscular aponeurosis. The fibro-osseous 

 ring thus formed gives passage to the brachial artery and the 



