PELVIS MINOR 



461 



The Pelvic Nerve Plexuses. There are three pelvic spinal 

 nerve plexuses, viz., the sacral, the pudenda!, and the coccygeal. 

 The former two are situated on the posterior wall of the pelvis 

 in front of the piriformis muscle, and the latter lies on the 

 coccygeus muscle close to the side of the coccyx. 



L!V 



5.1 



To piriformis 



To piriformis 



i Lumbo-sacral trunk 



Superior gluteal nerve 



Inferior gluteal nerve 



Nerve to quadratus femoris 

 Nerve to obturator internus 



Sciatic nerve 



Common 

 peroneal nerve 



/ 'Sciatic nerve 



\ Tibial nerve 

 --. Post. cut. N. of thigh (O.T. small sciatic) 



Perineal N. and dorsal N. of penis \ Pudendal 

 Inferior haemorrhoidal nerve /nerve 



Perforating cutaneous nerve 



-Y ' 



Nerves to levator ani 

 Coccygeal branches 



FIG. 217. Diagram of the Sacral, the Pudendal, and the 

 Coccygeal Plexuses. 



The Sacral and Pudendal Plexuses (O.T. Sacral Plexus). 

 The anterior rami of six spinal nerves take part in the 

 formation of the sacral and pudendal plexuses, viz., part of 

 the fourth lumbar nerve, the fifth lumbar, the first, second, 

 and third sacral nerves, and part of the fourth sacral nerve. 

 The first and second sacral nerves are very large, and of 

 about equal size ; the third is much smaller, and the fourth 



