42 NERVOUS SYSTEM. 



then divides two or three centimeters distad of the head of the 

 fibula into two main branches, N. peroneus superficialis (g) 

 and N. peroneus profundus (/). 



(1) N. peroneus superficialis (g). The superficial peroneal 

 nerve passes distad between the peroneus longus and peroneus 

 tertius. Near the ankle it becomes superficial, passing along 

 the concavity of the ankle across the transverse ligament which 

 binds down the tendons of the extensor longus (23) and tibialis 

 anterior (22), and thus reaches the dorsal side of the foot. Two 

 or three minute twigs are given off to the ankle, then the nerve 

 divides into four divisions. These pass distad to the toes, sub- 

 dividing so as to send a nerve to each side of each toe. 



(2) N. peroneus profundus (/). The deep peroneal nerve 

 passes between the tibialis anterior and extensor longus digi- 

 torum muscles, gives branches to these muscles, and passes 

 distad with the tibialis anterior artery, lying on the inner sur- 

 face of the tibialis anterior muscle. It passes onto the dorsum 

 of the foot, lying on the inner surface of the tendon of the 

 muscle. On the tarsus it divides into two branches. The 

 lateral branch passes into the extensor brevis digitorum, 

 while the medial one extends in the dorsal groove between 

 metatarsals four and five to the toes; here it divides into two 

 nerves which supply the contiguous sides of digits four and 

 five. 



b. N. tibialis (e). The tibial nerve passes distad parallel 

 with the peroneal nerve, but mediad of it. It passes between 

 the lateral and medial heads of the gastrocnemius, giving 

 off muscular branches to these, and to the plantaris and 

 soleus. It then passes between the plantaris and the medial 

 head of the gastrocnemius, and reaches the space between the 

 plantaris and flexor longus hallucis, where it passes distad. It 

 gives off, in the region just described, muscular branches to the 

 flexor longus digitorum, flexor longus hallucis, and tibialis 

 posterior. Below the middle of the lower leg the nerve 

 becomes superficial (Fig. 127, i, page 310), lying on the ven- 

 tral surface of the flexor longus hallucis. It passes in the 

 depression between the heel and the medial malleolus onto the 

 plantar surface of the tarsus, sends a small branch to the 



