138 



TOPOGRAPHICAL ANATOMY OF 



Dissection. — Reflect the extensor digitorum longus by cutting across 

 the middle of its fleshy belly. The three transverse ligaments which 

 hold the extensor tendons in position should also be cut through, in 

 order that the long extensor tendon may be turned aside from the 

 flexor aspect of the tarsus. Care must be exercised not to injure the 

 vessels and nerves related to the extensor longus tendon. 



M. peroNyEUS tertius. — Though this is called the third peroneal 

 muscle, there is some reason to question whether it actually corre- 



11. extensor digitorum longus. 



M. peronreus tertius. 



A. tibialis anterior. 

 M. peronseus tertius. 



Perforating tarsal artery and vein. 



A. dorsalis pedis. 



31. extensor digitorum brevis. 



M. peronams longus. 



M. tibialis anterior. 



V. saphena. 



II. tibialis anterior. 



V. metatarsea dorsalis medialis. 



Fig. 92. — Dissection of the Dorsal (Anterior) Aspect of the Tarsal Region. 

 1, 2, 3 = Transverse ligaments that retain the extensor tendons in position. 



sponds to the human muscle of this name. Its structure is noteworthy, 

 inasmuch as it is almost entirely tendinous. Functionally, therefore, 

 it is reasonable to assume that the muscle serves a purely mechanical 

 purpose. Doubtless, in conjunction with the largely tendinous plan- 

 taris muscle at the back of the leg, it acts as a passive mechanical stay, 

 which relieves the other muscle of the leg of a considerable amount of 

 strain when the animal is in the standing posture. The peronseus 

 tertius also causes mechanical flexion of the tarsal joint when the 



