356 THE MUSCLES OF THE OX 
IV. MEDIAL MUSCLES OF THE THIGH 
The sartorius arises by two heads, one from the tendon of the psoas minor 
and the iliae fascia, the other from the shaft of the ilium. The femoral vessels 
pass between them. 
The gracilis is more extensively united with its fellow at its origin than in the 
horse. 
The pectineus is large, and arises by a single head from the pubis and prepubie 
tendon. It divides into two branches, one of which is inserted as in the horse, 
while the other extends to the medial epicondyle of the femur. 
The adductor resembles that of the horse, but does not reach to the medial 
condyle of the femur. 
The quadratus femoris and obturator externus resemble those of the horse. 
The obturator internus has no iliac head, and its tendon passes through the 
obturator foramen. 
The gemellus is large; some of its fibers of origin join the obturator internus 
through the lesser sciatic foramen. 
V. MUSCLES OF THE LEG AND FOOT 
A. Dorso-LATERAL GROUP 
There are four digital extensors, two of which are fused with each other and 
the peroneus tertius in the upper third of the leg. 
1. The long digital extensor (M. extensor digitalis longus) arises in common 
with the peroneus tertius and the medial extensor in the extensor fossa of the femur, 
and separates from the other muscles near the middle of the leg. At the distal 
end of the tibia it terminates on a tendon which passes down over the hock (bound 
down by two annular ligaments) and ends like that of the thoracic limb. 
2. The medial digital extensor (M. extensor digiti tertii proprius) arises in com- 
mon with the preceding muscle and the peroneus tertius, and is covered by them 
to the distal third of the tibia. Its tendon passes under the annular ligaments 
between those of its cogeners and ends on the second phalanx of the medial digit. 
3. The lateral digital extensor (M. extensor digitalis lateralis s. digiti quarti 
proprius)! arises on the lateral ligament of the stifle joint and the lateral condyle of 
the tibia. Its tendon passes over the lateral surface of the hock, and terminates 
on the dorsal surface of the second phalanx of the lateral digit. 
The reinforcing bands from the suspensory ligament are arranged as in the 
forelimb. 
4. The short digital extensor (M. extensor digitalis brevis) resembles that of | 
the horse; it is inserted on the tendon of the long extensor. 
The peroneus longus (not present in the horse) is situated in front of the lateral 
extensor. It arises on the lateral condyle of the tibia and the fibrous band which | 
represents the shaft of the fibula. Its tendon passes downward and backward | 
over the lateral surface of the hock, crosses over that of the lateral extensor and | 
under the lateral ligament, and ends on the first tarsal bone and the proximal ent | 
of the large metatarsal bone. It is enveloped by a synovial sheath. It would ae | | 
parently act as an inward rotator at the hock joint. 
The peroneus tertius is a well-developed muscle which arises on the common | 
tendon with the long and medial extensors. It has a large, fusiform belly, which | 
is superficially situated on the front of the leg. Close to the tarsus it ends on a 
flat tendon, which is perforated by that of the tibialis anterior, and ends on the | 
proximal end of the large metatarsal and second and third (fused) tarsal bones. 
1 Lesbre regards this muscle as the homologue of the peroneus brevis of man and other 
pentadactyls. 
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