THE ABDOMEN 



901 



or it may exist as two plates, one for each surface, in which latter 

 case a small synovial ca\'ity exists between the two plates. When 

 the bones are forcibly separated, a portion of the cartilage is usually 

 left adherent to each auricular surface. The hgaments at the joint 

 are anterior, posterior, and oblique. The anterior sacro-iliac liga- 

 ment is composed of short fibres which are placed in front of the 

 joint. The posterior sacro-iliac ligament, which is very strong, 

 extends from the ligamentous surface of the ilium to the liga- 

 mentous surface of the sacrum and the transverse tubercles on the 

 dorsum of the bone, the direction of the fibres being downwards 

 and inwards. The oblique sacro-iliac ligament lies superficial to 

 the posterior, and extends from the posterior superior iliac spine 

 and the adjacent part of the iliac crest to the third and fourth 

 transverse tubercles on the dorsum of the sacrum. It is really a 

 detached part of the posterior sacro-iliac ligament. The great and 

 small sacro-sciatic ligaments are accessory to this joint. 



Ilio-lumbar Ligament 



Posterior Sacro-iliac 



Ligament 



Oblique Sacro-iliac — 

 Ligament 



Great Sacro-sciatic 

 Ligament 



Great Sacrorsciatic 

 Foramen 



Small Sacro-sciatic 

 Ligament 



Small Sacro-sciatic 

 Foramen 



_ _ Falciform Process of Great 

 Sacro-sciatic Ligament 



Obturator Membrane 



Fig. 377. 



-Ligaments of the Right Half of the PEL\ns 

 (Posterior View). 



The great or posterior sacro-sciatic ligament is attached by 

 one extremity to the posterior inferior iliac spine, and the sides 

 of the last three sacral and first coccygeal vertebrae, and by 

 the other extremity to the inner border of the tuber ischii. From 



