330 THE SPINAL NERVES. 



inent to the dorsum of the penis, alons; which it passes as far as the glans, where it 

 divides into filaments for the supply of that part. While passing through the deep 

 perineal fascia, it gives fine twigs for the supply of the constrictor urethras muscle ; 

 and on the dorsum of the penis, it is joined by branches of the sympathetic system, 

 and sends outwards numerous offsets to the integument on the upper surface and 

 sides of that organ. Some filaments also penetrate the corpus cavernosum. 



In the female the dorsal nerve of the clitoris is much smaller than the correspond- 

 ing branch in the male ; it is similarly distributed. 



Fig. 215. DISSECTION OP THE PERINEUM OF THE MALE TO SHOW THE DISTRIBUTION OF THE PUDIC 

 AND OTHER NERVES. (Hirschfeld and Leveille. ) | 



On the right side a part of the gluteus maximus muscle and the great sacro-sciatic ligament have been 

 removed : 1, great sciatic nerve of the right side ; 2, 2', on the right side, inferior gluteal nerve ; 2", 

 on the left side, gluteal cutaneous branches of the small sciatic ; 3, small sciatic nerve in the thigh ; 



4, 4, inferior pudendal nerve ; 4', network of this and the superficial perineal nerves in the scrotum ; 



5, right pudic nerve ; 6, superior branch or dorsal nerve to the penis : 7, external superficial perineal 

 branch ; 7', internal superficial perineal branch ; 8, deep or musculo-bulbal branches ; 9, inferior 

 hsemorrhoidal nerve ; 10, perforating cutaneous nerve. 



Varieties. In the high, form of plexus the pudic nerve may receive fibres from the fifth 

 lumbar (Eisler). Henle describes and figures a root to the pudic from the fifth sacral nerve, 

 but this was never met with by Eisler or Paterson. The inferior hsemorrhoidal nerve often 

 pierces the great or the small sacro-sciatic ligament on its way to the perineum (Eisler). The 

 external superficial perineal nerve may also pierce the great sacro-sciatic ligament. 



SUMMARY. The pudic nerve supplies the skin and muscles of the perineum, the 

 penis, and part of the scrotum in the male ; and the clitoris, labia, and other corre- 

 sponding parts in the female. It communicates with the inferior pudendal branch of 

 the small sciatic nerve. 



Great sciatic nerve. The great sciatic nerve (nervus ischiadicus'), the largest 

 nerve in the body, supplies the muscles at the back of the thigh, and by the branches 

 continued from it gives nerves to all the muscles below the knee and to the greater 

 part of the integument of the leg and foot. The several joints of the lower limb 

 receive filaments from it and its branches. 



This large nerve is the continuation of the main part of the sacral plexus. It 

 extends from the lower border of the pyriformis muscle to somewhat below the 

 middle of the thigh, where it separates into two large divisions, named the internal 

 and external popliteal nerves. At first it lies in the hollow between the great 



