90 THE SKELETON OF THE HORSE 
notch of the ulna. The lateral condyle (Condylus lateralis) 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 igament 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 anconzus projects. 
Fic. 65.—Proximat Extremity or Lerr HUMERUS OF Fic, 66.—Distan Extremity or Lerr Humerus or 
Horse; Enp View. Horse; Enp View. 
1, Intertuberal (or bicipital) groove; 2, 3, anterior 1, Medial condyle; 2, lateral condyle; 3, part of 
parts of lateral and medial tuberosities; 4, fossa; 5, 6, medial epicondyle to which medial ligament is attached; 
posterior parts of lateral and medial tuberosities; 7, 4, depression in which lateral ligament is attached; 
head. 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) 
