THE PLANTAR NERVE i6i 



of the flexor perforans muscle. In front of the artery is the internal 

 metacarpal vein. 



This relationship is maintained until they arrive at a point just above 

 the fetlock, where the artery becomes slightly more deeply seated, allow- 

 ing the vein and nerve to approximate more closely to one another. This 

 must be remembered, for the dipping of the artery frequently occurs 

 just at the point which is selected as the seat of operation in plantar 

 neurectomy. About midway between the knee and fetlock the internal 

 plantar nerve gives off a communicating branch, which winds 

 obliquely downwards and outwards behind the flexor tendons to join 

 the external plantar nerve at a point which is distant between one 

 and two inches above the nodular inferior extremity of the outer splint 

 bone. 



This point directs that the seat selected for neurectomy of the 

 external plantar nerve should be a little lower down the limb than that 

 for internal plantar neurectomy, in order that the external plantar nerve 

 may be severed below the point of union with it of this communicating 

 branch. 



On a level with the apex of the sesamoid bone the plantar nerve 

 divides into two branches. The anterior of these divisions crosses the 

 vessels and runs down in front of the digital vein. To it the name 

 anterior digital nerve is given. The posterior division, which is much 

 the larger, is continued downwards in an almost vertical direction 

 behind the digital artery and in close proximity to it. This nerve, with 

 its accompanying artery and vein, lies in a well-marked groove which 

 may be felt on the most prominent part of the fetlock. Just below the 

 level of the base of the sesamoid bone this nerve gives off a small branch, 

 which runs obliquely forwards across the digital artery and becomes 

 placed between the artery and its corresponding vein. This is the 

 middle digital nerve. Its seat of origin may be subject to much varia- 

 tion, as also may be its size, and cases are not uncommonly met with 

 wherein this division is entirely absent. 



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