138 ORIGIN AND DISTRIBUTION OF THE NERVES. 



The metacarpal nerves continue down the leg, over the 

 fetlcck joint, where they become the plantar nerves ; these 

 pursue their course behind their corresponding blood-vessels to 

 the back part of the foot, which they penetrate to the inner 

 sides of the lateral cartilages. 



The plantar nerve detaches a branch from the fetlock to 

 the lateral cartilage ; another passes to the fatty frog, yhe 

 final branch enters a hole in the back, and lower part of the 

 coffin bone, in company with the plantar artery, and there 

 divides and distributes its ultimate branches around the 

 edges of the sole. 



NERVES OF THE HIND EXTREMITY. 



The crural nerve is derived partly from the second, third, 

 fourth, and fifth lumbar nerves. It makes its appearance 

 under the transverse process of the loins, and proceeds in a line 

 with the external iliac artery. It gives off filaments to the 

 psoas magnus, iliacus, rectus, and vastus interims muscles. 

 It also gives off cutaneous filaments : one runs to the stifle, 

 and ends in ramifications upon the fore part of the thigh. The 

 other continues down the leg, and can be traced as low as the 

 fetlock. 



The obturator nerve, contributed to by third and fourth 

 lumbar nerves, sweeps round the brim of the pelvis, and 

 detaches twigs to the obturator muscles. Its ultimate fila- 

 ments are expended on the triceps and gracilis. 



The gluteal nerve, after leaving the cavity of the pelvis, 

 accompanies the gluteal artery, and passes into the substance 

 of the gluteal muscles. 



The sciatic nerve derives its origin from the sacral and last 

 of the lumbar nerves ; after leaving the cavity of the pelvis, 

 passes between the hip joint and the tuberosity of the ischi- 

 um, and plunges into the substance of the haunch. Here it 

 divides into branches called the popliteal nerves. At the 

 hock its principal branch separates into the external and inter- 

 nal metatarsal nerves : the former runs over the flexor pedis 

 to the os calcis. Their subsequent course and ultimate distri- 



