THE PERIPHERAL NERVOUS SYSTEM. 403 



plantar surface of the heel, and divides into two branches, the 

 medial and the lateral plantar nerves. 



(1) N. plantaris medialis. The medial plantar nerve 

 passes along the medial border of the flexor brevis digitorum 

 and divides into two branches. One passes to the medial 

 (second) digit, supplying both sides; the other supplies the 

 third digit in the same way. Both send branches to the fibrous 

 pad on the sole of the foot. 



(2) N. plantaris lateralis. The lateral plantar nerve 

 passes laterad across the tendon of the flexor longus digitorum 

 to its lateral edge. At about the proximal end of the metatarsi 

 it divides into two branches. The lateral branch passes clistad 

 to the ventral surface of the fifth digit. The medial branch 

 passes beneath the tendon of the. flexor longus digitorum and 

 transversely across the interossei; it divides into numerous 

 tendons which innervate the interossei and other short muscles 

 of the sole of the foot. 



4. N. pudendus (Fig. 162, /; Fig. 112, 8, page 265). 

 This arises (Fig. 162, /) from the sacral plexus caudad of the 

 great sciatic nerve. It has two roots, one from the second 

 sacral, one from the third, and it may also receive a small 

 accession from the great sciatic nerve (//) three or four centi- 

 meters caudad of the origin of the latter. It passes at first 

 dorsolaterad, laterad of the coccygeus muscle, then curves 

 mediad toward the anus. It divides into two branches: one 

 passes to the base of the penis, sends twigs into the compressor 

 urethrae muscle, and passes onto the dorsal surface of the penis. 

 This branch is N. dorsalis penis ; it extends with the artery of 

 the same name to the glans. The second branch of N. puden- 

 dus (N. hemorrhoidalis medius) passes to the anus and inner- 

 vates the muscles and other structures about the caudal end of 

 the rectum. In the female, branches of N. pudendus supply 

 the urogenital sinus and adjacent structures (Fig. 112, 8). 



5. N. cutaneus femoris posterior (Fig. 162, k; Fig. 

 163, //). This arises from the sacral plexus, its roots coming 

 chiefly from the second and third sacral nerves, and passes 

 caudodorsad, at first in close connection with N. pudendus. 

 It then accompanies the posterior gluteal artery and vein, sends 



