THE POSTERIOR TIBIAL ARTERY. 



839 



From external calcanean 



of the posterior tibial and peroneal communicating branches. Conversely, when the lower por- 

 tion of the posterior tibial is wanting, it may be replaced by the peroneal, which then gives rise 

 to the plantar arteries. Occasionally the peroneal is larger than usual, and may give origin to 

 the anterior tibial artery, and it may give off the nutrient artery for the tibia. 



The anterior peroneal artery is sometimes absent, but more frequently it is larger than 

 usual and inosculates with the anterior tibial. Occasionally the lower portion of this latter ves- 

 sel is wanting, and the anterior peroneal may then take its plfice, being continued downward 

 upon the dorsum of the foot as the dorsalis pedis and giving off the branches which normally 

 arise from that vessel. 



3. The Communicating Artery. — The communicating artery (r. commuoicans) 

 (Fig. 736) extends transversely outward across the posterior surface of the tibia, beneath 

 the tendon of the flexor 



longus hallucis and the ^^^- 739- 



tendo Achillis, and an- 

 astomoses with the 

 communicating branch ,^^^^„^, ^^,^^„^^„ ^, 

 of the peroneal. posterior tibial 



4. The Internal 

 Malleolar Artery. — 



The internal malleolar 

 artery (a. malleolaris 

 posterior medialis) (Fig. 

 740) passes directly in- 

 ward, beneath the ten- 

 dons of the flexor 

 longus digitorum and 

 tibialis posticus, to 

 ramify over the internal 

 surface of the inner 

 malleolus, anastomos- 

 ing with the internal 

 malleolar branch of the 

 anterior tibial artery. 



5. The Internal 

 Calcaneal Artery. — 

 The internal calcaneal 

 artery (ramus calcaaei 

 medialis) (Fig. 736) 

 arises from the lower 

 part of the posterior 

 tibial, just before it 

 divides into the two 

 plantar vessels. It is 

 frequently represented 

 by several branches 

 which descend along 

 the inner side of the 



Internal annular 



ligament, cut edge 



Inner malleolus 

 Abductor hallucis 



Internal plantar 



Flexor longus 



hallucis tendon 



Princeps hallucis. 



Internal calcaneal ot 

 external plantar 

 Plantar fascia, cut 



Flexor brevis digitorum 



Abductor minimi digiti 

 -External plantar artery 



Interosseous arteries 

 dividing into 



digital branches 



Arteries of plantar surface of right foot ; superficial dissection. 



tuberosity of the os calcis, supplying the neighboring parts of the integument and 

 anastomosing with branches of the internal malleolar and posterior peroneal arteries. 

 6. The Internal Plantar Artery. — The internal plantar artery (a. plantaris 

 medialis) (Fig. 740) is the smaller of the two terminal branches of the posterior tibial. 

 It arises in the groove between the internal malleolus and the os calcis and is directed 

 at first downward and forward, under cover of the abductor hallucis, and then forward 

 along the inner border of the foot, between the abductor hallucis and the flexor brevis 

 digitorum, terminating opposite the head of the first metatarsal bone by anastomosing 

 with one or other of the two branches distributed to the plantar surface of the 

 great toe. 



Branches. — In its course it gives oflf tmiscular branches to the abductor hallucis and the 

 flexor brevis digitorum, cutaneous branches to the integument over the inner border of the foot, 

 and articular branches to the neighboring tarsal joints. In addition, it usually gives oflf near its 



