338 



THE ARTICULATIONS 



middle than at the extremities ; attached by its broad base to the posterior inferior 

 spine of the ilium, to the fourth and fifth transverse tubercles of the sacrum, and 

 to the lower part of the lateral margin of that bone and the coccyx. Passing 

 obliquely downward, outward, and forward, it becomes narrow and thick, and 

 at its insertion into the inner margin of the tuberosity of the ischium it increases 

 in breadth, and is prolonged forward along the inner margin of the ramus, forming 

 what is known as the falciform ligament. The free concave edge of this prolonga- 

 tion has attached to it the obturator fascia, with which it forms a kind of groove, 

 protecting the internal pudic vessels and nerve. One of its surfaces is turned 

 toward the perinseum, the other toward the Obturator internus muscle. 



The posterior surface of this ligament gives origin, by its whole extent, to fibres 

 of the Gluteus maximus. Its anterior surface is united to the lesser sacro-sciatic 



ANTERIOR Or LESSER 



SACRO-SCIATIC 



LIGAMENT. 



femur. 1 



FIG. 240. Articulations of pelvis and hip. Posterior view. 



ligament. Its external border forms, above, the posterior boundary of the great 

 sacro-sciatic foramen, and, below, the lower boundary of the lesser sacro-sciatic 

 foramen. Its lower border forms part of the boundary of the perinaeum. It is 

 pierced by the coccygeal branch of the sciatic artery and coccygeal nerve. 



The Lesser or Anterior Sacro-sciatic Ligament, much shorter and smaller 

 than the preceding, is thin, triangular in form, attached by its apex to the spine 

 of the ischium, and internally, by its broad base, to the lateral margin of the 

 sacrum and coccyx, anterior to the attachment of the great sacro-sciatic ligament, 

 with which its fibres are intermingled. 



It is in relation, anteriorly, with the Coccygeus muscle ; posteriorly, it is covered 

 by the great sacro-sciatic ligament and crossed by the internal pudic vessels and 

 nerve. Its superior border forms the lower boundary of the great sacro-sciatic 

 foramen ; its inferior border, part of the lesser sacro-sciatic foramen. 



These two ligaments convert the sacro-sciatic notches into foramina. The 

 superior or great sacro-sciatic foramen is bounded, in front and above, by the 



