612 A MANUAL OF ANATOMY. 



and third sacral nerves, issues from the great sacrosciatic 

 foramen below the pyriformis, curves around the base of 

 the ischial spine and re-enters the pelvic cavity and is dis- 

 tributed to the obturator internus muscle. 



As the nerve crosses the spine it gives a branch to the 

 gemellus superior. Here it lies external to the internal 

 pudic artery. (The artery lies between the internal pudic 

 nerve (internal) and the nerve to the obturator internus 

 (which is external).) 



The Nerve to the Quadratus Femoris. 



This muscular branch arises from the third sacral nerve, 

 leaves the pelvic cavity through the great sacrosciatic 

 foramen, close to the bone, then passes under (anterior to) 

 the gemellus superior, tendon of obturator internus, and 

 gemellus inferior muscles, then over (posterior to) the ten- 

 don of the obturator externus to the anterior surface of the 

 quadratus femoris to which it is supplied. 



The gemellus inferior is supplied by a branch from this 

 nerve. 



The Gluteal Artery. Figs. 112, 114, 126, 127. 



This is the largest of the three arteries which leave the 

 pelvis through the great sacrosciatic foramen. It is really 

 the continuation of the posterior division of the internal 

 iliac and passes out through the great sacrosciatic foramen 

 above the pyriformis muscle, close to the bone. A half- 

 inch from the margin of the foramen it divides into a 

 superficial and deep branch. 



( i ) The superficial branch. This breaks up into branches 

 which ramify beneath and within the gluteus maximus 

 muscle and supply the surrounding parts. (2) The deep 

 branch. Gives a nutrient artery to the ilium and then 

 divides into a superior and an inferior branch, which pass 



