CHAPTER V 



THE JOINTS 



THE SACRO-ILIAC JOINT 



This is the joint which is formed between the auricular facet on the 

 sacral surface of the ilium and a similar facet on the superior surface of 

 the sacrum. It is a paired joint, and is of the arthrodial variety. 



The ligaments of this joint are four in number, which were named 

 by Rigot sacro-iliac, superior ilio-sacral, inferior ilio-sacral, and great 

 sacro-sciatic. 



The sacro-iliac ligament consists of fibres which are attached to the 

 roughened impressions which surround the articular surfaces. 



Superior Ilio-Sacral Ligament. — This is cord-like, and it runs from the 

 angle of the croup backwards along the tips of the superior spines of 

 the sacrum, becoming continuous with the supraspinous ligament of the 

 lumbar region. It is applied closely to the corresponding ligament or 

 the opposite side of the body. 



Inferior Ilio-Sacral Ligament. — This is a triangular membranous sheet, 

 the fibres of which run obliquely downwards and backwards. It arises 

 from the ischiatic border of the ilium, the limit of its attachment to this 

 bone being the angle of the croup superiorly, and the special tubercle 

 found on this border about three or four inches from this angle 

 inferiorly. Near the angle of the croup this ligament is confounded with 

 the one previously described. 



Sacro-Sciatic Ligament. — This is the great membranous expansion 

 which forms the greater part of the lateral boundary of the pelvic 



