ARTICULATIONS OF THE PELVIS 



291 



2. LIGAMENTS PASSING BETWEEN THE SACRUM AND ISCHIUM (Fig. 239). 



The Great Sacrosciatic (Posterior). 

 The Small Sacrosciatic (Anterior). 



The great or posterior sacrosciatic ligament (ligamentum sacrotuberoswri) (Figs. 

 239 and 240) is situated at the lower and back part of the pelvis. It is flat, and 

 triangular in form; narrower in the 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 for- 



Femurl 



FIG. 239. Articulations of pelvis and hip. Posterior view. 



ward, 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 

 process of the great sacrosciatic ligament or the falciform ligament (processus 

 falciformis). The free concave edge of this prolongation 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 perineum, 

 the other toward the Obturator internus muscle. 



Relations. The superficial surface of this ligament gives origin, by its whole extent, to fibres 

 of the Gluteus maximus muscle. Its deep surface is united to the lesser sacrosciatic ligament. 

 Its external border forms, above, the posterior boundary of the great sacrosciatic foramen, and, 

 below, the posterior boundary of the lesser sacrosciatic foramen. Its lower border forms part 

 of the boundary of the perineum. It is pierced by the coccygeal branch of the sciatic artery 

 and the coccygeal nerve. 



