•196 



THE MUSCULATURE 



The abductor hallucis (fig. 419), the largest and most superficial of these 

 muscles, lies on the border of the sole medial to the short flexor muscle. It passes 

 from the calcaneus across the tendons of the long flexor muscles, and is inserted 

 into the medial side of the base of the first phalanx of the great toe and into the 

 medial side of the long extensor tendon. It is partly fused to the medial belly of 

 the flexor hallucis brevis. The flexor hallucis brevis (fig. 421) is a bicaudal 

 muscle which lies over the first metatarsal. It arises in the region of the cune- 

 iform]bones and is inserted on each side of the base of the first phalanx. Between 



Fig. 420. — Second Layer of the Muscles of the Sole. 



Origin of abductor digiti V 



Part of abductor digiti V 



Flexor digiti V brevis 



Abductor digiti V 

 Lumbricales 



Tendon of flexor digitorum 

 brevis 



Flexor digitorum brevis 

 Abductor hallucis 



Quadratus plantae 

 Flexor digitorum longus 



Flexor hallucis longus 



Flexor hallucis brevis 

 Adductor hallucis 

 Abductor hallucis 



Tendon of flexor digitorum brevi 



its two bellies and insertions runs the tendon of the long flexor of the great toe. 

 Proximally and medially the flexor brevis is crossed by the abductor hallucis. 

 Its tendons are fused with thos(^ of the abductor and the oblique head of the ad- 

 ductor. The adductor hallucis (fig. 421) is composed of two distinct heads, an 

 oblique and a transverse. The oblique head extends from the long plantar liga- 

 ment under cover of the tendons of the flexor digitorum longus and the lumbrical 

 muscles to the lateral side of the base of the first phalanx of the great toe. Its 

 tendon of insertion is joined by th(! transverse head, which arises from the capsules 

 of the third to the fifth metatarso-phalangcal joints. Beneath the adductor lie 

 the more medial interosseous musch^s. 



These muscles perform not only the functions indicated by their names, but 

 also extend the second phalanx. They correspond fairly well with those of the 

 thumb. The ojjponens is not normally present in the foot. The nerve supply for 

 the atlductor is ironi the lateral ((jxternal) plantar nerve; that for the other muscles 

 is from the medial (internal) j)lantar. 



The abductor hallucis (fig. 419). — Origin. — From (1) the medial process of the tuber 

 calcanei; (2) the deep surface of the neighbouring plantar fascia; (3) the laciniate (internal 



