90 



THE SKELETON OF THE HOHSE 



notch of the ulna. The lateral condyle (Condylus laterahs) is much smaller and 

 is placed somewhat lower and further back, giving the extremity an oblique ap- 

 pearance; it is marked by a wide shallow groove. The coronoid fossa (Fossa coro- 

 noidea) is situated in front, above the groove on the medial condyle ; it furnishes 

 origin to part of the extensor carpi, and lateral to it is a rough depression from 

 which the common digital extensor arises. Behind and above the condyles are two 

 thick ridges, the epicondyles. The medial epicondyle (Epicondylus medialis) 

 is the more salient; it furnishes origin to flexor muscles of the carpus and digit, 

 and bears a tubercle for the attachment of the medial ligament of the elbow joint. 

 The lateral epicondyle (Epicondylus lateralis) bears laterally the condyloid crest 

 (Crista condyloidea), which forms here the outer boundary of the musculo-spiral 

 groove, and gives origin to the extensor carpi radialis. Below this is a rough excava- 

 tion in which the lateral ligament is attached. The distal border of the epicondyle 

 gives attachment to the ulnaris lateralis. Between the epicondyles is the deep 

 olecranon fossa (Fossa olecrani), into which the processus anconseus projects. 



Fig. 65. — Proximal Extremity of Left Humerus of 

 Horse; End ^"IEW. 

 1, Intertuberal (or bicipital) groove; 2, 3, anterior 

 parts of lateral and medial tuberosities; 4, fossa; 5, 6, 

 posterior parts of lateral and medial tuberosities; 7, 

 head. 



Fig. 66. — Distal Extremity of Left Humerus of 

 Horse; End \'ie\v. 

 1, Medial condyle; 2, lateral condyle; 3, part of 

 medial epicondyle to which medial ligament is attached; 



4, depression in which lateral Ugament is attached; 



5, 6, areas of attachment of flexor and extensor muscles 

 of carpus and digit; 7, olecranon fossa. 



Development. — The humerus ossifies from six centers, viz., three primary 

 centers for the shaft and extremities, and three secondary centers for the lateral 

 tuberosity, the deltoid tuberosity, and the medial condyle respectively. The 

 proximal end fuses with the shaft at about three and one-half years, the distal at 

 about one and a half years of age. 



THE RADIUS 



The radius is much the larger of the two bones of the forearm in the horse. 

 It extends in a vertical direction from the elbow, where it articulates with the hum- 

 erus, to the carpus. It is gently curved, the convexity being dorsal. It consists 

 of a shaft and two extremities. 



The shaft (Corpus radii) is curved in its length, somewhat flattened from before 

 backward, and widened at its ends. It presents for description two surfaces and 

 two borders. The dorsal surface (Facies dorsalis) is smooth, slightly convex in 

 its length, and rounded from side to side. The volar surface (Facies volaris) 



