GLUTEAL NERVE. 475 



men. It is in relation behind with the pyriformis muscle, and in front 

 with the pelvic fascia, which latter separates it from the branches of 

 the internal iliac artery, and from the viscera of the pelvis. 



The Branches of the sacral plexus are divisible into the internal and 

 the external; they may be thus arranged : 



Internal. External. 



Visceral, Muscular, 



Muscular. Gluteal, 



Internal pudic, 

 Lesser ischiatic, 

 Greater ischiatic. 



The Visceral nerves are three or four large branches which are de- 

 rived from the fourth and fifth sacral nerves : they ascend upon the 

 side of the rectum and bladder ; in the female upon the side of the 

 rectum, the vagina and the bladder ; and interlace with the branches 

 of the hypogastric plexus, sending in their course numerous filaments 

 to those viscera. 



The Muscular branches given off within the pelvis are one or two 

 twigs to the levator ani ; an obturator branch ; which curves around 

 the spine of the ischium to reach the internal surface of the obturator 

 internus muscle ; a coccygeal branch ; and an haemorrhoidal nerve 

 which passes through the two ischiatic openings and descends to the 

 termination of the rectum to supply the sphincter and the integu- 

 ment. 



The Muscular brandies supplied by the sacral plexus externally to 

 the pelvis are, a branch to the pyramidalis ; a branch to the gemellus 

 superior ; and a branch of moderate size which descends between the 

 gemelli muscles and the ischium, and is distributed to the gemellus 

 inferior, the quadratus femoris, and the capsule of the hip-joint. 



The GLUTEAL NERVE (superior gluteal) is a branch of the lumbo- 

 sacral ; it passes out of the pelvis with the gluteal artery, through the 

 great sacro-ischiatic foramen, and divides into a superior and an infe- 

 rior branch. The superior branch follows the direction of the superior 

 curved line of the ilium, accompanying the deep superior branch of 

 the gluteal artery, and sending filaments to the gluteus medius and 

 minimus. The inferior passes obliquely downwards and forwards 

 between the gluteus medius and minimus, distributing numerous fila- 

 ments to both, and terminates in the tensor vaginae femoris muscle. 



The INTERNAL PUDIC NERVE arises from the lower part of the 

 sacral plexus, passes out of the pelvis through the great sacro-ischiatic 

 foramen below the pyriformis muscle, and takes the course of the 

 internal pudic artery. While situated beneath the obturator fascia 

 it lies below that vessel and divides into a superior and an inferior 

 branch. 



