242 



THE ARTICULATIONS 



The Anterior Sacro-iliac Ligament (Fig. 164) consists of numerous thin bands 

 which connect the anterior surfaces of the sacrum and ilium. 



The Posterior Sacro-iliac (Fig. 165) is a strong interosseous ligament, situated 

 in a deep depression between the sacrum and ilium behind, and forming the chief 

 bond of connection between those bones. It consists of numerous strong fasciculi 

 which pass between the bones in various directions. Three of these are of large 

 size : the two superior, nearly horizontal in direction, arise from the first and 

 second transverse tubercles on the posterior surface of the sacrum, and are inserted 

 into the rough, uneven surface at the posterior part of the inner surface of the 

 ilium. The third fasciculus, oblique in direction, is attached by one extremity to 

 the third transverse tubercle on the posterior surface of the sacrum, and by the 

 other to the posterior superior spine of the ilium ; it is sometimes called the 

 oblique sacro-iliac ligament. 



The position of the sacro-iliac joint is indicated by the posterior superior spine of the ilium. 

 This process is immediately behind the centre of the articulation. 



2. LIGAMENTS PASSING BETWEEN THE SACRUM AND ISCHIUM (Fig. 165). 



The Great Sacro-sciatic (Posterior). 

 The Lesser Sacro-sciatic (Anterior). 



The Great or Posterior Sacro-sciatic Ligament is situated at the lower and 

 back part of the pelvis. It is flat, and triangular in form ; narrower in the 



ANTERIOR Or LESSER 



SACRO-SCIATIC 



LIGAMENT. 



[Femur.] 



FIG. 165. Articulations of pelvis and hip. Posterior view 



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 



