224 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. 



Fig. 308. — The muscles of the dorsum of the foot. 

 The compartments of the cruciate ligament have been opened and the tendons of the long extensors cut off shortly 

 before their insertions. 



Fig. 309. — The plantar aponeurosis. 



Fig. 310. — The superficial layer of the plantar muscles. 

 The plantar fascia has been largely removed from the surface of the flexor digitorum brevis. 



brane. The upper portion of the muscle is adherent to the origin of the tibialis anterior and 

 to the deep fascia of the leg. The tendon is situated in the anterior margin of the muscle and 

 receives the middle and inferior fibers, which pursue a course similar to those of the extensor 

 hallucis. During its passage through the cruciate ligament or just above it, the tendon sub- 

 divides into four fiat, rather weak tendons, which run to the dorsal aponeuroses of the second 

 to the fifth toes. 



The peronaeus tertius (Figs. 306 and 315) seems to be a part of the extensor digitorum. 

 It arises from those fibers of the latter muscle which come from the lower portion of the fibula; 

 its flat tendon runs beneath the cruciate ligament with those of the extensor digitorum and is 

 inserted by means of a flat tendinous expansion into the dorsal surface of the fifth metatarsal 

 bone. 



The extensor digitorum extends the four outer toes; and the peronaeus tertius assists in producing dorsal flexion of 

 the foot. Both muscles are supplied by the deep branch of the peroneal nerve. 



THE MUSCLES OF THE FOOT, 



THE MUSCLES OF THE DORSUM. 



Unlike the back of the hand, the dorsal aspect of the foot is provided with two short 

 extensor muscles. * 



The extensor hallucis brevis (Figs. 306, 308, and 315) is a small, flat, triangular muscle 

 which is situated upon the dorsal surface of the bones, joints, and ligaments of the tarsus. It 

 arises in common with the extensor digitorum brevis, with which it is adherent, from the dorsal 

 surface of the calcaneus, passes forward and inward, and in the region of the base of the first 

 metatarsal bone becomes continuous with a flat narrow tendon which runs over the metatarsal 

 bone beneath the tendon of the extensor longus, the two tendons together forming the dorsal 

 aponeurosis. 



The extensor digitorum brevis (Figs. 306, 308, and 315) arises together with the preceding 

 muscle from the dorsal surface and the adjacent portion of the lateral surface of the calcaneus, 

 and subdivides into three (rarely four) muscular bellies which terminate in very slender tendons 

 passing to the second, third, and fourth toes, and fusing with the tendons of the extensor digi- 

 torum longus to form dorsal aponeuroses. 



Both muscles upon the dorsum of the foot are supplied by the deep peroneal nerve. They extend the toes. A 

 tendon for the little toe is rarely present. 



