THE LOWER LIMB 52? 



The posterior peroneal artery is the continuation of the peroneal 

 artery. It passes behind the external malleolus, and along the 

 outer border of the foot for a variable distance. Its branches 

 are chiefly distributed over the outer surface of the os calcis, 

 and these external calcaneal branches take part in the external 

 malleolar anastomosis. Over the prominence of the heel they 

 anastomose freely with the internal calcaneal branches of the 

 external plantar, and on the outer border of the foot the pos- 

 terior peroneal again anastomoses with branches of the external 

 plantar. 



The peroneal artery is accompanied by two venae comites, which 

 ultimately join the posterior tibial venae comites; 



Varieties of the Posterior Tibial Artery. — The vessel is sometimes very small, 

 in which cases the peroneal artery is of large size, as well as the communicating 

 branch normally given off about i inch above the ankle-joint, and so the small 

 posterior tibial artery- is reinforced. In rare cases the vessel does not reach 

 the ankle, and it may even be entirely absent, in which cases there is always 

 a large peroneal artery to make good the deficiency. 



Varieties ol the Peroneal Artery. — The level at which this vessel arises from 

 the posterior tibial is subject to variety. Its normal origin is fully i inch 

 below the commencement of the posterior tibial, but it may arise lower down 

 or higher up, or it may even spring from the pophteal, or from the anterior 

 tibial. In some cases it is of large size, in order to compensate for a small 

 posterior tibial. In other cases the peroneal artery may stop short of the 

 ankle, its place being taken by a branch of the posterior tibial. The anterior 

 peroneal branch is sometimes of large size, in order that it may reinforce 

 a small anterior tibial, or even furnish the dorsahs pedis artery. 



Posterior Tibial Nerve. — ^This nerve is the continuation of the 

 internal pophteal. It commences at the lower border of the 

 popliteus muscle, and its normal termination corresponds with the 

 lower border of the internal annular ligament, where it divides into 

 internal and external plantar nerves. The division, however, 

 frequently takes place at the upper border of the internal annular 

 ligament, or as the nerve passes beneath it. The nerve closely 

 accompanies the posterior tibial artery throughout the whole of 

 its course. It lies at first on the inner side of the artery, with the 

 intervention of the internal vena comes, but it only maintains this 

 position for about i| inches. It then crosses over the vessel, and 

 descends upon its outer side, the external vena comes intervening. 

 The general relations of the nerve are similar to those of the corre- 

 sponding artery. 



Branches. — These are muscular, fibular, calcaneo - plantar, 

 articular, and terminal. 



The muscular branches are given off from the upper part 

 of the nerve, and supply the flexor longus digitorum, tibiahs 

 posticus, flexor longus hallucis, and soleus, the branch to the last 

 muscle entering it on its deep or anterior surface near the centre 

 of the leg. 



The fibular branch is a long nerve which is usually associated 

 at its origin with the branch to the flexor longus hallucis. It 

 accompanies the peroneal artery, and furnishes (i) a medullary 



