276 SKELETON. 



The Sacro-Iliac Ligament (Lig. Sacro-lliacum) is next to the 

 articular faces of the bones. It surrounds the joint, but is much 

 stronger on its posterior face. It consists in an assemblage of 

 ligamentous fasciculi, some of which have obtained, by the 

 writers on Syndesmology, particular names, but which it would 

 scarcely add to the student's information to designate. On the 

 front of the joint this ligament is uniform, and consists of a 

 plane of short, strong fibres, passing from the margin of one 

 bone to that of the other. But, on the posterior surface, it is 

 much more irregular, and arises from the first two eminences 

 near the lateral margin of the sacrum, and from that surface of 

 the sacrum between these eminences and its articular face. 

 From thence the sacro-iliac ligament goes to be inserted into 

 the rough surface of the ilium, immediately behind its articular 

 face; it fills up there a considerable space, and, from its posi- 

 tion, must be extremely irregular. Its strength is so great, 

 that in forcing the joint the ligament does not rupture, but parts 

 preferably from the surface of the ilium, and sometimes brings 

 with it a lamella of bone. 



The bones of the pelvis are also fastened by two other very 

 strong ligaments, the sacro-sciatic. 



The Posterior Sacro-Sciatic (Lig. Sacro-lschiadicum majus) 

 is the most considerable of the two. It arises from the poste- 

 rior inferior spinous process of the ilium, from the margin of 

 the sacrum below this bone, and somewhat from its posterior 

 surface, and from the first bone of the coccyx. It goes down- 

 wards and outwards, becomes thicker in its middle, but nar- 

 row; it then spreads out, and is inserted along the internal mar- 

 gin of the tuberosity of the ischium. Its anterior extremity is 

 extended along the internal face of the crus of the ischium for 

 some distance, and has the obturator internus muscle adhering 

 to it. Its fibres, where they converge from their origin, are 

 separated into planes by masses of fat and by blood vessels. 



The Anterior Sacro-Sciatic Ligament (Lig. Sacro-lschiadi- 

 cum minus] is much smaller than the other, and is placed in 

 front of it. It arises from the margin, and somewhat from the 

 posterior surface of the sacrum, below the ilium ; and from the 

 lateral margin of all the bones of the coccyx. The fibres con- 



