TIBIAL NEUROTOMY 179 



besides this branch it also supplies another, which accom- 

 panies the perforating pedal artery directly into the depths 

 of the tarsal articulations. The continuing branch traces its 

 course, over the anterior aspect of the metatarsus, where it 

 is lost in the skin. This nerve is, therefore, important in the 

 surgical treatment of spavin. The superficial peroneal, or 

 musculocutaneous nerve, runs parallel to the deep peroneal 

 in the tibial region, but is much more superficial. It lies 

 directly beneath the tibial fascia in the groove between the 

 peroneus and extensor pedis muscles. Approaching the 

 hock it lies along the external side of the extensor pedis 

 tendon, traces its course over the external aspect of the tar- 

 sus about midway between the latter tendon and that of the 

 peroneus, and then is lost in the skin of the metatarsal 

 region. This nerve probably has little influence over the 

 bones, but furnishes sensibility to the peri-articular struc- 

 tures along the region it traverses. 



The external saphenic nerve is related to the tendo- 

 Achilles externally in the tibial region. At the level of the 

 os calcis it reflects forward and is distributed over the ex- 

 ternal aspect of the hock posteriorly, and then over the re- 

 gion of the external splint bone, to -become lost cutaneously. 

 The internal saphenic nerve, unlike the others concerned 

 in the innervation of the tarsus, is not a radicle of the sciatic. 

 Its remote origin is the anterior portion of the lumbo-sacral 

 plexus, while that of the sciatic is the posterior portion. 

 This nerve occupies the internal aspect of the femoral and 

 tibial regions, terminating on the anterior portion of the 

 hock and metatarsus. It gives off a number of branches to 

 the femoral muscles, and in the upper third of the tibial 

 region divides into three or four branches. Two of these 

 branches accompany the internal saphenic vein-, one on 

 either side; another large branch winds over the belly of the 

 flexor metatarsi in the middle third of the tibial region and 

 loses itself around the anterior part of the hock, while an- 

 other one continues down the internal aspect of the tibia 

 over the front of the hock internally, and thence downward 

 into the skin of the metatarsal region. The ramuscules of 

 this nerve are easily traced into the tarsal synovials an- 

 teriorly and are therefore prominently concerned in supply- 

 ing sensibility to important tarsal structures. 



Conclusions. — The hock receives sensibility from the fol- 

 lowing sources, named in the order of their importance: 

 (i) The deep peroneal. (2) The internal plantar. (3) 

 The unnamed branch leaving the posterior tibial four inches 



