68 OUTLINES OF EQUINE ANATOMY. 



outer, andpreseuts one prominent convex surface, decreas- 

 ing in size towards the outer condyle whicli consists of two 

 convexities. These condyles are connected together by a 

 slight articulatory concavity, which extends posteriorly into 

 the supra- condyloid fossa. On either side of this extremity 

 is a depression for attachment of a lateral ligament of the 

 elbow-joint. In the centre of the articulatory surface is a 

 peculiar roughened depression with rounded edges ; this 

 must not be mistaken for ulceration. 



RADIUS AND ULNA. 



The basement structure of the forearm comprises two 

 bones, both of which, in the ox and other animals, extend 

 to the knee. In the horse, however, the posterior bone or 

 ulna terminates about opposite the superior part of the 

 inferior third of the radius or anterior bone, though traces 

 of it may sometimes be seen united to the inferior extremity 

 at the postero-extemal part. The RADIUS is a long round 

 bone, extending from the elbow to the knee, presenting a 

 shaft, a superior and an inferior extremity. The shaft 

 centrally is convex from side to side, and oJso from above 

 downwards. It is smooth anteriorly, and over it play 

 extensor metacarpi and extensor pedis. From the outer 

 margin of the middle third extensor metacarpi obliquus 

 runs obliquely over this surface downwards and inwards. 

 The jJosterior surface is slightly concave from side to side, 

 and to its outer margin the inferior part of the ulna is 

 attached to an extremely elongated triangular roughened 

 surface. The rest of the central part of this surface affords 

 attachment to radialis accessorius and the superior sus- 

 pensory ligament. The external and internal sharp margins 

 -afford attachment to the faschia which sustains the muscles 

 of the forearm, while more externally placed than the ulna, 

 extensor suffraginis is situated, enclosed between two 

 layers of faschia, one of which is attached in front, the 

 other behmd it. The ?/jjper extremity of the radius, at the 

 -extreme superior part, presents an articulatory surface 

 corresponding to that of the inferior extremity of the 

 humerus. It consists of an inner and an outer part, almost 

 separated by a roughened groove, extending forward from 

 the posterior margin of the bone to within about one quarter 

 qI an inch of the anterior margin, which is here slightly in- 



