THE LOWER LIMB 507 



border of the interosseous membrane (or through a superior hiatus 

 in it), join to form one trunk, which unites with the trunk formed 

 by the junction of the venae comites of the posterior tibial artery 

 to form the pophteal vein. 



The anterior tibial artery in the upper fourth of the leg is 

 separated from the anterior tibial nerve by the fibula and the 

 extensor longus digitorum, the artery having passed forwards 

 between the tibia and fibula, and the nerve having wound obliquely 

 round the outer side of the bone. At the junction of the upper 

 fourth and lower three- fourths of the leg the nerve, having pierced 

 the antero-extemal intermuscular septum and extensor longus 

 digitorum, comes into contact with the artery, along the outer 

 side of which it descends for a short distance. It then lies 

 on the artery for a little, and finally it again takes up a 

 position upon the outer side of the vessel in the lower fourth of 

 the leg. 



Branches. — The branches from above downwards are as follows : 

 posterior tibial recurrent ; superior fibular ; anterior tibial re- 

 current ; muscular ; internal malleolar ; and external malleolar. 



The posterior tibial recurrent artery is an inconstant branch. 

 When present it arises from the anterior tibial artery whilst on 

 the back of the leg. Its course is upwards beneath the popliteus 

 muscle, and it is distributed to that muscle, the posterior liga- 

 ment of the knee-joint, and the superior tibio-fibular articulation. 

 It anastomoses with the external and internal inferior articular 

 arteries on the back of the leg. 



The superior fibular artery also arises from the anterior tibial 

 whilst on the back of the leg. Its course is outwards behind 

 the neck of the fibula, where it pierces the soleus, and it is 

 distributed to that muscle, the peroneus longus, and the adjacent 

 integument. 



The anterior tibial recurrent artery arises from the anterior 

 tibial whenever it reaches the front of the leg. Entering the 

 upper part of the tibialis anticus, to which, as well as to the 

 superior tibio-fibular joint, it gives branches, it ascends to the 

 external tuberosity of the tibia, in company with the recurrent 

 articular branch of the external popliteal nerv^e. Its terminal 

 branches anastomose with the external and internal inferior arti- 

 cular arteries. 



The muscular branches are very numerous, and are distributed 



chiefly to the muscles on the anterior aspect of the leg. Some 



offsets, however, reach the integument, and others, piercing the 



interosseous membrane, terminate in the tibialis posticus, in which 



I they anastomose with branches of the posterior tibial artery. 



! The internal malleolar artery is a small branch which arises 



I from the inner side of the anterior tibial near the lower end of the 



I tibia. Its course is inwards beneath the tendon of the tibialis 



anticus, and it is distributed over the internal malleolus, where it 



i anastomoses with (i) the internal malleolar branches of the pos- 



