THE PERONEAL ARTERY. 465 



malleolus ; below this point, the vessel is covered only by tlie common 

 integument and the fascia. The peroneal artery rests at first against 

 the upper part of the tibialis posticus muscle, and afterwards in the 

 greater part of its course, it is surrounded by fibres of the flexor longus 

 poUicis, lying close inside the projecting posterior ridge of the fibula. 

 Descending beyond the outer malleolus, it terminates in branches on 

 the outer surface and back of the os calcis. 



Branch.es. ^(«) Muscular branches from the upper part of the peroneal artery 

 ]:)ass to the soleus, the tibialis posticus, the flexor longus pollicis, and the jDeronei 

 muscles. 



{b) A nutrient artery enters the fibula. 



(c) The anterior 'peroneal artery arises about two inches above the outer 

 malleolus, and, immediately piercing the interosseous membrane, descends along 

 the front of the fibula, covered by the peroneus tertius muscle, and. dividing into 

 branches, reaches the outer ankle, and anastomoses with the external malleolar 

 branch of the anterior tibial artery. It supplies vessels to the ankle-joint, and 

 ramifies on the front and outer side of the tarsus, inosculating more or less freelj- 

 with the tarsal arteries. 



{(l~) The terminal branches anastomose with the external malleolar and -n-ith 

 the tarsal arteries on the outer side of the foot ; and behind the os calcis with 

 ramifications of the posterior tibial artery. 



(r) The eonimunieating branch, lying close behind the tibia, about two inches 

 from its lower end, is a transverse branch situated close to the bones, which con- 

 nects the peroneal with the posterior tibial artery. 



Varieties. — The posterior tibial artery, as well as the anterior tibial, is 

 lengthened in those instances in which the popliteal artery di\-ides higher up 

 than usual. Not unfrequently the posterior tibial arteiy is diminished in size, 

 and is subsequently reinforced either by a transverse branch from the peroneal 

 in the lower part of the leg, or, in rare .instances, by two transverse vessels, one 

 crossing close to the bone, and the other over the deep muscles. In other 

 instances the posterior tibial may exist only as a short muscular triuik in the 

 upper pai't of the leg, while an enlarged peroneal artery takes its place from 

 aljove the ankle downwards into the foot. 



The jjeroneal ai1;eryhas been found to arise lower down than usual, about three 

 inches below the popliteus muscle ; and. on the contrary, it sometimes commences 

 higher up from the posterior tibial, or even from the popliteal artery itself. In 

 some cases of high division of the popUteal artery, the peroneal artery is trans- 

 ferred to the anterior tibial. It more frequently exceeds than falls short of 

 the ordinary dimensions, being enlarged to reinforce the posterior tibial. In 

 those rare instances in which it is lost before reaching the lower part of the leg, 

 a branch of the posterior tibial takes its place. The anterior peroneal branch is 

 sometimes enlarged to compensate for the small size of the anterior tibial artery 

 in the lower part of the leg, or to supply the place of that artery on the dorsum 

 of the foot ; or it may be absent and be replaced by the anterior tibial. In a 

 singular case, recorded by Otto, the peroneal artery was whoUy wanting. 



PLANTAR ARTERIES. 



The external and internal plantar arteries are the branches into 

 which the posterior tibial divides in the hollow of the calcaneum, where 

 it is covered by the origin of the abductor pollicis. 



The internal plantar artery, much smaller than the external, is 

 directed forwards, along the inner side of the foot. Placed at first 

 under cover of the abductor pollicis, it passes forwards in the groove 

 between that muscle and the short flexor of the toes, near the line 

 separating the middle from the inner portion of the plantar fascia, and 

 on reaching the extremity of the first metatarsal bone, considerably 



