ARTICULATIONS AND LIGAMENTS. 



117 



Sacro-ischiatic Articulation. The os innominatum and sa- 

 crum are united by two important ligaments the great sacro- 

 scldtic (posterior) ligament, and the lesser sacro-sciatic (or an- 

 terior) ligament. 



The great sacro-sciatic ligament arises from the fourth and 

 fifth transverse tubercles of the sacrum, from spine of ilium, 

 sacrum, and coccyx, and passes downward, outward, and forward, 

 to be inserted into the inner margin of the tuberosity of the 

 ischium, bo ing prolonged forward as the falciform ligament 

 protecting the internal pudic veins and nerves. 



FIG. 88. 



1, manubrium; 2, gladiolus; 3, xiphoid appendix; 4, first dorsal 

 vertebra; 5, last dorsal vertebra; 6, first rib. 



It converts the sacro-sciatic notch into the lesser sacro- 

 sciatic foramen, transmitting the obturator internus muscle and 

 nerve, the internal pudic vessels and nerves. 



The lesser sacro-sciatic ligament arises from the lateral 

 margin of the sacrum and coccyx, and is inserted into the spine 

 of the ischium. It converts the sacro-sciatic notch into the 

 greater sacro-sciatic foramen, transmitting the pyriformis mus- 

 cle, gluteal vessels, superior gluteal nerve, sciatic vessels and 

 nerves, and the internal pudic vessels and nerves. 



Sacro-coccygeal articulation is an amphiarthrodial joint, 

 resembling the vertebral, having an interarticular fibre-cartilage, 

 and connected together by 



