380 THE MUSCLES OF THE DOG 
The capsularis is usually present, but is small and pale. 
The sartorius consists of two parts. The anterior part arises from the tuber 
coxe and its flat tendon ends on the patella. The posterior part arises from the 
lateral border of the ium and ends on the medial surface of the tibia, its tendon 
blending with that of the gracilis. The anterior part is superficial in front of the 
tensor fascize latee and forms here the anterior contour of the thigh. 
The graciles are not so much fused at their origin as in the other animals. 
Its anterior part is thin. Its broad tendon is inserted into the tibial crest, and 
blends with those of the sartorius and semitendinosus. 
The pectineus is long and slender. It arises from the ilio-pectineal eminence 
and ends on the medial branch of the linea aspera above the distal end of the femur. 
The adductor femoris is a large muscle which arises on the ventral surface of 
the pubis and ischium; it ends on the linea aspera of the femur and the medial 
surface of the stifle. It is commonly separable into two parts. 
The peroneus tertius is represented by a tendinous band which arises on the 
medial surface of the tibia below the crest. It passes on the medial surface of the 
tibialis anterior, blends with the annular ligament above the tarsus, and is attached 
to the joint capsule and the proximal end of the third metatarsal bone. 
Arloing and Lesbre say: “‘The third peroneus is a proper extensor of the fifth digit; it 
is a very feeble, fleshy band, situated behind the peroneus brevis, which it partially covers. It 
is attached to the upper part of the fibula, and is continued by a long, delicate tendon which 
passes in the same malleolar groove with the muscle mentioned; it then crosses behind the tendon 
of the peroneus longus and extends to the phalanges of the outer digit, where it joins one of the 
branches of the common extensor.” 
The tibialis anterior is large and superficial. It arises on the lateral condyle 
and crest of the tibia, and is inserted into the first metatarsal bone, or into the 
first tarsal and second metatarsal. 
There are four extensors of the digits. 
1. The long digital extensor (M. extensor digitalis longus) is fusiform, and lies 
largely under the preceding muscle. It arises from the extensor fossa of the femur. 
The tendon is bound down by two annular ligaments: the proximal one, at the 
distal end of the tibia, encloses also the tendon of the tibialis anterior; the distal 
one is at the lower part of the tarsus. The tendon divides at the tarsus into 
four branches, which end on the distal phalanges of the digits (second to fifth). 
2. The lateral digital extensor (M. extensor digitalis pedis lateralis s. digiti 
quinti) has a small, unipennate belly which is covered by the peroneus longus 
and the deep digital flexor. It arises on the fibula below the head. The tendon 
descends behind that of the peroneus longus, inclines forward under the lateral 
ligament of the tarsus and the peroneus tendon, and joins the branch of the 
tendon of the long extensor for the fifth digit. 
3. The extensor hallucis longus is a very thin muscle which arises from the | 
fibula under the long extensor. Its delicate tendon accompanies that of the tibialis 
anterior to the first metatarsal bone, or becomes lost in the fascia. 
4. The extensor digitalis brevis has three divisions. It arises on the fibular | 
tarsal bone and the adjacent ligaments. The three tendons are inserted into 
the second, third, and fourth digits, blending with the interossei. (Sometimes 
there is a tendon for the rudimentary first digit, which may represent the extensor 
hallucis brevis. There may be a fourth belly for the tendon to the second digit.) 
The peroneus longus arises on the lateral condyle of the tibia, the head of 
the fibula, and the lateral ligament. The belly does not extend to the middle of 
the leg, and the long tendon passes down the leg parallel to the fibula. It is bound 
down in the groove of the lateral malleolus by an annular ligament, crosses the 
plantar surface of the tarsus transversely, and ends on the first metatarsal bone. 
The peroneus brevis is unipennate and arises from the distal half or more 
