SOLE OF THE FOOT 387 



the deep surface of the intermediate part of the plantar 

 aponeurosis, and from the intermuscular septum on each side 

 of it. About the middle of the sole the fleshy belly divides 

 into four slips, which end in slender tendons for the lateral 

 four toes. The tendons enter the fibrous flexor sheaths of 

 the toes, and will be afterwards studied. The flexor digitorum 

 brevis is supplied by the medial plantar nerve. It is a flexor 

 of the first interphalangeal joints and the metatarso-phalangeal 

 joints of the lateral four toes. 



M. Abductor Hallucis. The abductor of the great toe 

 takes origin from the medial aspect of the medial process of 

 the tubercle of the calcaneus, from the medial intermuscular 

 septum, from the distal border of the ligamentum laciniatum, 

 and from the medial part of the plantar aponeurosis, which 

 covers it. A strong tendon issues from the fleshy belly. 

 This is joined, on its lateral and deep surface, by fibres of 

 the medial head of the flexor hallucis brevis, and it is 

 inserted into the medial aspect of the base of the proximal 

 phalanx of the great toe. The abductor hallucis is supplied 

 by the medial plantar nerve. It abducts the great toe from 

 the middle line of the second toe. 



M. Abductor Digit! Quinti (O.T. Abductor Minimi Digiti). 

 The origin of the abductor of the little toe extends 

 medially under cover of the flexor digitorum brevis. The 

 posterior part of the latter muscle which "has already been 

 divided must, therefore, be turned well backwards to expose 

 the medial part of the origin of the abductor of the little toe. 

 The abductor digiti quinti is then seen to have a broad origin 

 from both the medial and lateral processes of the calcaneus. 

 It also arises from the lateral intermuscular septum, and the 

 lateral part of the plantar aponeurosis, which covers it. Its 

 tendon is inserted into the lateral aspect of the base of the 

 first phalanx of the little toe. The abductor digiti quinti 

 is supplied by the lateral plantar nerve. It abducts the little 

 toe from the middle line of the second toe. 



Dissection. The abductor hallucis has already been sepa- 

 rated from the medial side of the medial process of the calcaneus. 

 Separate it now from the distal border of the laciniate ligament, 

 and turn it medially ; then divide the laciniate ligament until the 

 origins of the plantar arteries and nerves are exposed. They are 

 the terminal branches of the posterior tibial artery and the tibial 

 nerve, and they arise in the distal part of the leg under cover of 

 the proximal part of the laciniate ligament. 



