LIGAMENTS AND MUSCLES OF THE HORSE. 19 



ways ; and the interosseous is the inferior navicular liga- 

 ment of that anatomist. 



POSTERIOR EXTREMITY. 

 , SACROILIAC ARTICULATION. 



1. Sacro-iliac {or Capsular.) — Composed of strong fibres, pass- 



ing between the sacrum and ilium, surrounding the joint. 



2. 'Superior .Sacro-iliac- Is a band attached to the internal 



angle of the ilium and the summits of the sacral spines. 



3. Inferior Sacro-iliac. — Is a triangular expansion, fixed an- 



teriorly to the internal border of the ilium, inferiorly to the 

 border of the sacrum, and posteriorly continuous with the 

 coccygeal fascia. 



4. Sacro-sciatic— Quadrilateral in shape. Upper border at- 



tached to the border of the sacrum and 1st coccygeal bone ; 

 lower border, to the superior ischiatic spine and tuDer-is- 

 chii ; anterior border short, and helps to form the greater 

 sacro-sciatic foramen ; posterior border is thin, and united 

 to the adductor magnus muscle. 

 Foramina. 



L Great Sacro-sciatic. — Is formed by the internal border of the 

 ilium and anterior border of the sacrf>-sciatic ligament. It 

 transmits the great sciatic nerve, and gluteal vessels and 

 nerves. 



2. Lesser Sacro-sciatic. — Is formed by the lower border of the 

 sacro-sciatic ligament, and the external border of the is- 

 chium ; transmits the common tendon of the obturator in- 

 ternus and pyriformis muscles. 

 Synovial Membrane. 



This is rudimentary. 

 Movement. 



Scarcely appreciable. 



