Chap, xxiii.] THE ANKLE AND FOOT. 535 



divided is shown in Fig. 57. It is not usual to dissect 

 up any of the muscular tissue of the sole, as shown 

 in Agatz's plate. It should be noted that the integu- 

 ments of the heel derive their blood supply, which is 

 very free, mainly from the external calcaneal branch 

 of the posterior peroneal artery, and the internal 

 calcaneal from the external plantar. 



If the heel incision is carried sufficiently far back 

 to divide the trunk of the posterior tibial artery, the 

 heel flap is deprived of the last-named source of blood 

 supply. The posterior tibial artery bifurcates upon a 

 line drawn between the tip of the inner malleolus and 

 the centre of the convexity of the heel. 



The nerves supplying the integuments of the heel 

 are the calcaneal branch of the external saphenous 

 and the calcaneal and plantar cutaneous twigs from 

 the posterior tibial. 



In PirogoflPs amputation the parts divided 

 in the anterior flap are the same as in Syme's operation. 

 In the heel or sole flap the same structures also are 

 cut as in the corresponding flap in a Syme, with the 

 exception that the tendo Achillis is not divided, the 

 flexor brevis digitorum, abductor pollicis, abductor 

 minimi digiti, and flexor accessorius are divided more 

 extensively, and the plantar vessels are cut farther 

 from the bifurcation. 



Chopart's operation is an amputation at the 

 medio-tarsal joint. In the dorsal flap are cut the 

 integuments, the extensor communis and brevis digi- 

 torum, extensor proprius pollicis, tibialis anticus, 

 peroneus tertius and brevis, the musculo-cutaneous, 

 anterior tibial, and two saphenous nerves, the dorsal 

 artery, and the dorsal plexus of veins. In the plantar 

 flap are found divided the integuments, plantar fascia, 

 flexor brevis digitorum, abductors of the great and 

 little toes, flexor accessorius, and tibialis posticus 

 tendon. If the flap be well dissected up from the 



