THE LOWER EXTREMITY, POSTERIOR. 615 



It is usually pierced by the coccygeal branch of the 

 sciatic artery. 



The Small Sacrosciatic Ligament. Fig. 114. 



This arises from the side of the sacrum and coccyx, an- 

 terior to the great sacrosciatic ligament, with which it blends. 



It is inserted into the spine of the ischium. It converts 

 the great sacrosciatic notch into a foramen (assisted by the 

 great sacrosciatic ligament to a slight extent). From it 

 arise some fibres of the coccygeus muscle. 



The Sacrosciatic Foramina. Figs. 114, 127. 



These are formed by the great and small sacrosciatic 

 ligaments bridging over the great and small sacrosciatic 

 notches as mentioned above. 



The greater foramen transmits the pyriformis muscle ; 

 above the muscle the gluteal artery and vein and the supe- 

 rior gluteal nerve. Below the muscle the sciatic artery and 

 vein, the great and small sciatic nerves, the internal pudic 

 artery, vein, and nerve, and the nerves to the obturator 

 internus and quadratus femoris muscles. 



The smaller foramen transmits the obturator internus 

 muscle (its tendon), the internal pudic artery, vein, and 

 nerve, and the nerve to the obturator internus muscle. 



DISSECTION. 



Cut through the gluteus medius at its outer and middle thirds. Reflect the 

 two parts. 



Gluteus Minimus. Figs. 118, 127. 



Origin. From the external surface of the ilium between 

 the middle and inferior curved lines, extending from the 

 margin of the great sacrosciatic notch behind, to the notch 

 between the anterior, superior, and inferior spines of the 

 ilium. 



