THE LEG 373 



and at its termination it lies midway between the prominence 

 of the calcaneus and the medial malleolus. 



In its proximal two-thirds the posterior tibial artery is situated 

 deeply, being covered by the superficial muscles of the calf. 

 In the distal third of the leg, where it lies between the tendo 

 calcaneus and the medial border of the tibia, it is relatively 

 superficial and is covered merely by the integument and two 

 layers of fascia. More distally it is covered by the ligamentum 

 laciniatum. Proximo-distally it rests against the fascia on the 

 tibialis posterior, the flexor digitorum longus, the tibia, and 

 the posterior aspect of the ankle joint (Fig. 163). 



Throughout its entire course the posterior tibial artery is 

 closely accompanied by two vena comites. The tibial nerve 

 is at first on its medial side, but it soon crosses behind the 

 vessel, and then proceeds distally on its lateral side. 



The following are the branches which issue from the 

 posterior tibial artery : 



1. Kami musculares. 



2. Rami cutanei. 



3. A. nutricia tibiae. 



4. A. peronsea. 



5. Rami calcanei mediales. 



3. Ramus communicans. 



7, A. plantaris medialis. 



S. A. plantaris lateralis. 



Arteria Peronaea. Although the peroneal artery is not 

 the first it is, as a rule, the largest branch of the posterior 

 tibial. It arises about 25 mm. or so distal to the com- 

 mencement of the parent trunk, and at first runs, obliquely 

 distally, and laterally, to the fibula. In this first part of its 

 course it rests against the fascia covering the tibialis posterior 

 and it is covered by the soleus ; then it descends along the 

 medial crest of the fibula, covered by the flexor hallucis longus 

 and lying first, against the fascia covering the tibialis 

 posterior, and next, against the interosseous membrane. Im- 

 mediately above the ankle joint it emerges from under cover 

 of the flexor hallucis longus, passes behind the distal tibio- 

 fibular joint and the ankle joint, medial to the peronaei 

 tendons, and it breaks up on the lateral aspect of the 

 calcaneus into a number of lateral calcanean branches. 



The branches of the peroneal artery are : (i) muscular 

 branches to the adjacent muscles ; (2) a nutrient branch to 

 the fibula; (3) the perforating branch which pierces the 

 interosseous membrane near the distal tibio-fibular joint, and 

 has already been dissected on the dorsum of the foot (see 



