THE LOWER EXTREMITY, ANTERIOR. 593 



Action. Same as in the hand (q.v., page 389), to flex 

 the first set of phalanges, to extend the second and third 

 sets of phalanges, to abduct the toes from the middle line 

 drawn through the second toe. 



The Anterior Tibial Artery. Figs. 124, 225. 



This artery is the anterior branch of bifurcation of the 

 popliteal, just at the lower border of the popliteus muscle. 

 See page 623. The course of the anterior tibial artery is 

 forward between the two heads of the tibialis posticus 

 muscle, then between the tibia and fibula, where the artery 

 crosses over the top of the interosseous membrane to gain 

 the front of the leg. 



It turns downward resting upon the interosseous mem- 

 brane and between the tibialis anticus and the extensor 

 longus digitorum for the upper third of its course, then 

 between the tibialis anticus and the extensor proprius hallu- 

 cis for the middle third, then finally between the tendon 

 of the extensor proprius hallucis and the tibia for the 

 lower third. In front of the ankle joint the name of the 

 artery is changed to the dorsalis pedis. The artery has on 

 either side an accompanying vein which frequently commu- 

 nicate with each other. The anterior tibial nerve lies at the 

 outer side of the artery for its upper third, over the front 

 of the artery for its middle third, and then again at the outer 

 side of the artery for the lower third. 



The course of the artery is indicated upon the outer 

 surface of the leg by a line drawn from the inner 

 margin of the head of the fibula to the mid-point in front 

 of the ankle joint between the malleoli. The deeper 

 guide to the artery is the intermuscular space at the outer 

 margin of the tibialis anticus muscle, for the upper two- 

 thirds ; and between the tendons of the extensor proprius 

 38 



