POSTERIOR TIBIAL NEURECTOMY 179 



seat at this point may possibly account for the somewhat frequent in- 

 effectiveness of this operation in treating spavin. Upon careful dissection 

 a very slender branch which runs right across the usual seat of spavin 

 is found to be given off by this nerve. The branch for the greater part 

 of its course hes immediately under the skin, and hence is rarely seen 

 in an ordinary dissection, since it is usually removed in reflecting the 

 skin. Special dissection has therefore to be made for it. 



In a number of dissections where opportunity was presented for 

 taking measurements it was found that the above-mentioned branch was 

 given off from the posterior tibial nerve at a point the average distance 

 of which from the point of the hock was five inches {Veterinary Record, 

 April 29, 1905). It occurred to the writer that in cases where the exostosis 

 is fairly prominent and well-defined, lameness might be due to pressure 

 on this branch, and providing such were the case the seat usually recom- 

 mended for the performance of the operation was too low to be effective. 

 Shortly afterwards opportunity was presented for putting a higher seat 

 into practice, and the incision was made between six and seven inches 

 above the summit of the calcis, with satisfactory results. Other cases 

 have been attended with similar results, one of which, operated upon in 

 conjunction with Mr. G. H. Locke, M.R.C.V.S., of Manchester, is 

 frequently under the latter's observation, and has worked regularly since.* 

 There are several anatomical advantages in selecting a higher seat as 

 suggested. In this situation the nerve is slightly more superficial and is 

 more easily found. It is also further removed from the posterior tibial 

 artery, which lower down forms its sigmoid curve in the direction of 

 the nerve. Moreover, there is no risk of injuring the retrograde branch 

 of this artery, which in the lower seat ascends from the second curvature 

 of the flexure immediately in front of the nerve. 



Having made our cutaneous incision, about the breadth of the handle 

 of a scalpel in front of the tendon and parallel to it, the incision being 

 carried through the skin and superficial fascia ; on separating the lips 



* Veterinary Record^ May 12, 1906. 



