SOLE OF THE FOOT 391 



The muscular branches go to four muscles of the sole, viz., 

 the abductor hallucis, the flexor digitorum brevis, the flexor 

 hallucis brevis, and the most medial or first lumbrical muscle. 

 The branches which supply the abductor hallucis and the 

 flexor digitorum brevis arise from the trunk of the medial 

 plantar nerve a short distance from its origin. The nerve 

 to the flexor hallucis brevis arises from the digital nerve to 

 the medial side of the great toe, and the nerve to the first 

 lumbrical muscle springs from the digital nerve which 

 supplies the adjacent sides of the first and second toes. 



Nenrus Plantaris Lateralis (O.T. External Plantar Nerve). 

 The lateral plantar nerve corresponds to -the ulnar nerve in 

 the palm of the hand. It accompanies the lateral plantar artery 

 and possesses the same relations. In the interval between the 

 abductor digiti quinti and the flexor digitorum brevis, opposite 

 the base of the fifth metatarsal bone, it divides into a deep 

 and a superficial part. The deep division follows the plantar 

 arch, under cover of the flexor tendons. The superficial 

 division divides into two digital branches. 



From the trunk of the lateral plantar nerve proceed two 

 muscular branches, viz., to the abductor digiti quinti and to the 

 quadratus plantse. 



The first or lateral digital branch of the superficial part of 

 the lateral plantar nerve goes to the lateral side of the little 

 toe. It also gives muscular twigs to the flexor brevis digiti 

 quinti and the interosseous muscles in the fourth intermeta- 

 tarsal space. 



The second digital branch divides to supply the adjacent 

 sides of the fourth toe and little toe. It sends also a twig of 

 communication to the third terminal digital branch of the 

 medial plantar nerve. 



Dissection. Detach the abductor digiti quinti from its origin, 

 and turn it forwards, in order that a good display may be obtained 

 of the structures composing the second stratum of the sole. 



Second Layer of Muscles and Tendons. As the tendon 

 of the flexor hallucis longus enters the sole it grooves the 

 plantar surface of the sustentaculum tali and inclines medially, 

 deep to the tendon of the flexor digitorum longus, towards 

 the great toe. The tendon of the flexor digitorum longus, on 

 the other hand, inclines laterally superficial to the tendon 

 of the flexor hallucis longus to reach the middle of the foot, 

 i 25 c 



