842 



HUMAN ANATOMY. 



THE ANTERIOR TIBIAL ARTERY. 



The anterior tibial artery (a. tibialis anterior) (Figs. 742, 743) is the other terminal 

 branch of the popliteal. It begins at the lower border of the popliteus muscle, and is at 

 first directed forward, passing between the tibia and fibula and the two uppermost slips 

 of origin of the tibialis posticus, above the upper border of the interosseous membrane. 

 It then bends downward and traverses the entire length of the crus to the front of the 

 ankle-joint, where it becomes the dorsalis pedis artery. Its course may be represented 

 by a line drawn from the head of the fibula to a point half-way between the two malleoli. 



Relations. — In its course down the leg the anterior tibial artery rests posteriorly 

 upon the interosseous membrane, to which it is more or less firmly united by fibrous 

 bands ; in the lower quarter of its course it rests upon the front of the tibia. Anteriorly, 

 in the upper two-thirds of its course, it is overlapped by the tibialis anticus, lying along 

 the deep edge of the connective-tissue partition which separates that muscle from the ex- 

 tensor longus dig'itorum and the extensor proprius hallucis. Lower, however, it is 

 superficial, and just above the ankle-joint it is crossed obliquely, from without inward, 

 by the tendon of the extensor proprius hallucis, and then passes beneath the anterior 

 annular ligament. Internally to it is the tibialis anticus, and at the ankle-joint the ten- 

 don of the extensor proprius hallucis ; externally it has in its upper third the extensor 

 longus digitorum, in its middle third the extensor proprius hallucis, and at the ankle the 

 inner tendon of the extensor longus digitorum. The anterior tibial nerve lies to the 

 outer side of the artery in 'its upper and lower thirds ; in the middle third of the leg it 

 is usually in front of the vessel. 



Peroneus brevis 



Ext. longus hallucis 



Ext. longus 



digitorum 



-Tibialis 



anticus muscle 



-1 Tibia 



— Ant. tibial nerve 



— Ant. tibial artery 



- Companion vein 



Variations. — The anterior tibial artery, as it occurs in man, appears to be the result of a union 

 of two originally distinct vessels, both of which arise from the primitive peroneal artery and pass to 



the front of the leg. The up- 

 p permost of these forms the 



'^ ' greater portion of the artery, 



•' while the lower one, which 



is represented by the anterior 

 peroneal artery, forms only 

 the lower part of the anterior 

 tibial and its continuation 

 upon the dorsum of the foot, 

 the dorsalis pedis. In case of 

 failure in the union of these 

 two vessels, the anterior tibial 

 may appear to terminate in 

 muscular branches a short 

 distance above the ankle- 

 joint, the dorsalis pedis being 

 the continuation of the an- 

 terior peroneal. This ar- 

 rangement is not infrequent ; 

 more rarely the upper portion 

 of the vessel is greatly re- 

 duced, being represented 

 only by a small stem which 

 gives off the posterior and 

 anterior recurrent branches 

 as well as branches to the 

 popliteus muscle, the front of 

 of the leg, in such cases, being 

 sometimes supplied by an in- 

 dependent perforating branch 

 from the posterior tibial. 



Practical Consid- 

 erations. — The anterior 

 tibial artery is more often 

 wounded than the pos- 

 terior tibial because of its 

 more exposed position on the front of the limb and its close relation to the tibia. It is not 

 infrequently lacerated by the sharp edge of a fragment in fracture of that bone. It is 



Dissection of middle third of right leg, showing relations of anterior tibial 

 vessels and nerves; extensor muscles have been drawn aside. 



