160 THE CAT. [CHAP. v. 



it ends by being implanted into the inner end of that groove close to 

 and at least indirectly connected with the minute innermost nieta- 

 tarsal that of the hallux. 



This muscle aids in walking by pulling up the inner side of the 

 foot, and indirectly pressing the distal ends of the inner long meta- 

 tarsals upon the ground as a fulcrum. 



The peroneus brevis arises from the front and outer side of the 

 lower half (or more) of the fibula except close to the external 

 malleolus. It ends in a tendon which passes behind the external 

 malleolus, and beneath the tendon of the peroneus longus, and is 

 inserted into the proximal end of the fifth metatarsal. 



The peroneus quinti digiti springs from the upper and "outer half 

 of the fibula, and ends by a slender tendon which passes, in a 

 synovial sheath, behind the external malleolus, and is inserted into 

 the dorsum of the proximal phalanx of the minimus digit. 



The extensor brevis digitorum pedis is a short muscle which takes 

 origin from the concavity on the distal part of the dorsum of the 

 os calcis and from the dorsum of the cuboid. It divides into three 

 bellies, each of which ends in a strong tendon. The innermost tendon 

 divides at about the distal end of the metatarsals, one division going 

 to the proximal phalanx of the index, the other to that of the third 

 digit. 



The second tendon similarly divides, and goes to the third and 

 fourth digits. 



The third and outermost tendon goes to the fourth digit only. 



Thus the fifth digit receives no tendon from this muscle. 



Of the muscles behind the leg the largest is the gastrocnemius. 

 Two heads respectively arise from the two sesamoids, which are 

 placed one behind each of the two condyles of the femur. 



Another (third) head arises from the ligamentum patellae in 

 common with the plantaris. 



A fourth head (Fig. 83, 4 ) arises from the fascia investing the 

 peronei muscles and fibula. The third and fourth heads, with the 

 head from the sesamoid behind the external condyle, unite inextric- 

 ably with the plantaris. The head from the sesamoid behind the 

 internal condyle remains long distinct, but ultimately unites with the 

 other heads which, all having united, end below in a strong tendon 

 the tendo Achillis which is inserted into the hinder part of the 

 tuberosity of the os calcis, superficially to the insertion of the 

 soleus. Close to the heel, the tendon passes to the peroneal side of 

 that of the plantaris, the latter there appearing and becoming 

 superficial to it (Fig. 84). 



The plantaris arises from the ligamentum patelke in common with 

 the third head of the gastrocnemius. Below this origin it is closely 

 mixed up with the outer parts of the gastrocnemius though well 

 distinguished from the inner part of the latter. It forms below 

 a strong tendon, which becomes visible just above the tuberosity 

 of the os calcis on the tibial side of the tendo Achillis. It then 

 expands and glides over the pulley-like surface of the calcaneal 



