THE LEG 267 



longus is placed in the interval between the tibialis anterior 

 and the extensor digitorum longus. In its proximal part it 

 is hidden from view by those muscles, but near the ankle it 

 comes to the surface. It takes origin behind the extensor 

 digitorum longus, from an extremely narrow strip of the 

 anterior part of the medial surface of the body of the fibula, 

 in its middle two-fourths, and also from the adjoining part of 

 the interosseous membrane. Its tendon crosses the distal 

 part of the anterior tibial artery, and reaches the dorsum of 

 the foot by passing distally in front of the ankle-joint and 

 deep to the transverse and cruciate ligaments (p. 261). It 

 is inserted into the dorsal aspect of the base of the ungual 

 phalanx of the great toe. 1 It is not joined by the most medial 

 tendon of the extensor digitorum brevis. The extensor 

 hallucis longus is supplied by the deep peroneal nerve. 



M. Peronaeus Tertius. This is a small muscle which is con- 

 tinuous at its origin with the extensor digitorum longus. It 

 arises from the distal fourth of the anterior part of the medial 

 surface of the fibula, and from a corresponding extent of the 

 interosseous membrane. It also receives fibres from the 

 distal part of the anterior peroneal septum, which intervenes 

 between it and the peronaeus brevis. Its slender tendon is 

 inserted into the dorsal surface of the expanded base of the 

 fifth metatarsal bone. It is supplied by the deep peroneal nerve. 



Arteria Tibialis Anterior. The anterior tibial artery is 

 the smaller of the two terminal branches of the popliteal. 

 It takes origin in the posterior region of the leg, at the distal 

 border of the popliteus muscle, and it enters the anterior 

 crural region by passing forwards through the opening in the 

 proximal part of the interosseous membrane. In this part 

 of its course it lies close to the medial side of the neck of 

 the fibula, and appears, in the present dissection, immediately 

 distal to the lateral condyle of the tibia. In the anterior part 

 of the leg it takes a straight course downwards to the ankle- 

 joint. Then it reaches the dorsum of the foot, and receives 

 the name of dorsalis pedis. 



In the proximal two-thirds of the leg the anterior tibial 

 artery is very deeply placed. It lies upon the interosseous 

 membrane in the interval between the tibialis anterior on the 

 medial side, and the extensor digitorum longus and the 

 extensor hallucis longus on the lateral side. In the distal 



1 In most cases it likewise gives a slip to the base of the proximal phalanx. 



