328 THE MUSCLES OF THE DOG 



The capsularis is usually present, but is small and pale. 



The sartorius consists of two portions. It arises from the external angle 

 and border of the ilium. The anterior portion ends on the patella, the 

 posterior on the internal surface of the tibia, its tendon blending with that 

 of the gracilis. 



The graciles are not so much fused at their origin as in the other ammals. 



The pectineus is long and slender. It arises from the ilio-pectineal eminence 

 and ends on the internal branch of the linea aspera above the distal end of the 

 femur. 



There are two distinct adductors. The small anterior one ends on the proximal 

 third of the femur, the posterior one on the distal part of the femur and on the 

 inner face of the stifle joint. 



The quadratus femoris is short and strong. The other external rotators of 

 the thigh present no special features. 



The peroneus tertius is represented by a tendinous Ijand which arises on the 

 internal surface of the tibia below the crest. It passes downward on the inner 

 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 ]>ehind 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 external 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 anterior or long digital extensor (M. extensor digitalis longus) is fusi- 

 form, 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, and divides 

 below 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 lateralis) is feeble and semi- 

 pennate. It arises on the filnila below the head. The tendon passes under the 

 lateral ligament of the tarsus 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 l^ecomes lost in the fascia. 



4. The extensor digitalis brevis has three divisions. It arises on the fibular 

 tarsal bone ami the adjacent ligaments. The three tendons are inserted into 

 the second, third, and fourth digits, blending with the interossei. (Sometimes 

 there is fountl a tendon to 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 external condyle of the tibia, the 

 head of the fibula, and the lateral ligament. The long tendon passes down 

 the leg parallel to the fibula, crosses the plantar (posterior) surface of the 

 tarsus transversely, and ends on the first metatarsal bone. A short l^ranch is 

 detached to the ext(>rnal metatarsal bone. 



The peroneus brevis is semipennate and arises from the distal half or more 

 of the outer face of the tibia and the fibula. Its tendon accompanies that of 



