92 DISSECTION OF THE DOG 



cover of the biceps muscle. Disappearing between the long peroneal and deep 

 flexor muscles, it divides in the proximal half of the leg into deep and superficial 

 branches (n. peronseus profundus et n. peronseus superficialis). 



Before its division the common peroneal nerve supplies a branch to the 

 long peroneal muscle. 



N. peronseus superficialis. — The superficial branch of the common 

 peroneal nerve is included for a time in the septum between the peronseus 

 longus and the extensor digiti quinti muscles. Piercing the deep fascia over 

 the lateral aspect of the leg some little distance proximal to the tarsus, it becomes 

 subcutaneous, and has been followed over the dorsum of the pes where it supplies 

 a dorsal cutaneous nerve of the first digit, and the second, third, and fourth com- 

 mon dorsal digital nerves distributed to the second, third, fourth, and fifth digits. 



While still deep to the fascia of the leg, the superficial peroneal nerve 

 furnishes branches to the extensor digitorum longus, peronseus brevis, and 

 extensor digiti quinti muscles. 



N. peronjeus profundus. — From the point at which it leaves the common 

 peroneal nerve, the deep peroneal branch runs obliquely between the peronseus 

 longus on the one hand, and the extensor digiti quinti and deep flexor of the 

 digit on the other. Thus the nerve comes into contact with the anterior tibial 

 artery, alongside which and its continuation (the a. dorsalis pedis) it runs ver}^ 

 obliquely across the front of the tibia to the flexor aspect of the tarsus, where 

 it terminates in a medial and a lateral branch. The medial branch follows 

 the a. dorsalis pedis until that vessel disappears from the region, and then 

 follows the groove between the second and third metatarsal bones to form 

 the n. metatarsal dorsalis II. The lateral branch crosses the tarsus under 

 cover of m. extensor digitorum brevis, which it supplies, and then furnishes 

 the nn. metatarsei dorsales III et IV. 



While in the leg, the deep peroneal nerve contributes branches to the 

 peronseus longus, extensor digitorum longus, tibialis anterior, and extensor 

 hallucis longus muscles. 



A. tibialis anterior. — The anterior tibial artery is practically the con- 

 tinuation of the popliteal artery. By piercing the interosseous membrane 

 between the tibia and the fibula, the artery gains the lateral surface of the 

 former bone, along which it runs, with some degree of obliquity, towards the 

 tarsus. The peronseus longus, extensor digitorum longus, extensor hallucis 

 longus, and tibialis anterior muscles cover the artery in succession. 



Opposite the joint between the tibia and the talus, the anterior tibial artery 

 changes its name to that of dorsal artery of the pes (a. dorsalis pedis), which 

 crosses the flexor aspect of the tarsus, between the tendons of the anterior 

 tibial and long extensor muscles, to disappear into the space between the 

 bases of the second and third metatarsal bones. Before disappearing, the 

 a. dorsalis pedis supplies the second, third and fourth dorsal ^metatarsal arteries 

 (aa. metatarsese dorsales II, III, et IV). 



