396 Anatomy Applied to Medicine and Surgety. 



Syme's Operation, or disarticulation at the ankle joint. 

 In this, the incision starts from the tip of the outer 

 malleolus, a little nearer to its posterior than to its an- 

 terior border, and is carried down the heel at right angles 

 to the long axis of the foot, across the sole, and then, ver- 

 tically upwards on the inner side, to a point half an inch 

 below the inner malleolus. The flap is cleared from the 

 under surface and the tuberosities of the os calcis and 

 then from its posterior surface. The dorsal incision is 

 made by connecting the ends of the plantar incision by a 

 cut that sweeps across the front of the ankle. In disar- 

 ticulating, the knife should cut the lateral ligaments from 

 within outwards, as, otherwise, it would be difficult to 

 divide them, and, in the division of the tibia, the saw line 

 should be one-quarter of an inch above the inferior margin 

 ,of the bone. 



It is important that the inner end of the plantar in- 

 cision should be directly below the internal malleolus and 

 not behind it, since, in the latter case, the posterior tibial 

 or the origin of the plantar arteries would be severed, and, 

 since the blood supply for the heel flap is derived chiefly 

 from the internal calcanean branches of the external plan- 

 tar, or from the posterior tibial just at its bifurcation, it 

 would necessarily follow that an incision terminating be- 

 hind the inner malleolus would sever these trunks, and, 

 therefore, seriously impair the nutrition of the heel flap. 



