INTERPUBIC DISC. 431 



substance. In some bodies the fissure extends through the whole 

 of the disc, so as to divide it completely into two. 



The thin OBTURATOR MEMBRANE (fig. 159, 6) almost closes Obturator 

 the thyroid foramen, and is composed of fibres crossing in 

 different directions. It is attached to the bony margin of the 

 foramen, except above where the obturator vessels pass through ; 

 and at the lower and inner part of the aperture it is connected to 

 the pelvic aspect of the hip-bone. The surfaces of the ligament 

 give attachment to the obturator muscles. Branches of the obturator 

 vessels perforate it. 



