230 



THE ARTICULATIONS OF THE HORSE 



The joint capsule is verj- close fitting, and is attached around the margins of 

 the articular surfaces. It is reinforced by the ventral sacro-iliac ligament (Lig. 

 sacro-iliacum ventrale), which surrounds the joint; this is exceedingly strong above, 

 where it occupies the angle between the ilium and the wing of the sacrum; it con- 

 sists chiefly of nearly vertical fibers. 



The movements are inappreciable in the adult — stability, not mobility, being 

 the chief desideratum. 



LIGAMENTS OF THE PELVIC GIRDLE 



The following hgaments (Ligg. cinguli extremitatis pelvinse) may be regarded 

 as accessory to the sacro-ihac joint, although not directly connected with it: 



Fig. 244. — Pelvic Ligaments and Hip Joint. 

 1 , Dorsal sacro-iliac ligament; B, lateral sacro-iliac ligament; 3, sacro-sciatic ligament; 4, greater sciatic foramen; 



6, lesser sciatic foramen; 6, line of attachment of intermuscular septum between biceps femoris and semifcendinosus; 



7, capsule of hip joint; 8, eapsularis muscle; 9, lateral tendon of origin of rectus femoris; 10, tuber sacrale; 11, tuber 

 coxae; i J, shaft of ilium; i5, superior ischiatic spine; i 4. pubis; iJ, tuber ischii; it?, trochanter major; i 7, semimem- 

 branosus; 18, fifth lumbar spine; 19, 20, first and second coccygeal vertebrae. 



The dorsal sacro-iliac ligament (Lig. sacro-iliacum dorsale breve) is a strong 

 band which is attached to the tul:)cr sacrale and the summits of the sacral spines. 



The lateral sacro-iliac ligament (Lig. sacro-iliacum dorsale longum) is a tri- 

 angular, thick sheet which is attached in front to the tuber sacrale and adjacent 

 part of the medial border of the ilium al)ove the great sciatic notch, and below to 

 the lateral border of the sacrum. It blends above with the dorsal sacro-iliac liga- 

 ment, below with the sacro-sciatic ligament, and behind with the coccygeal fascia. 



The sacro-sciatic ligament (Lig. sacroischiadicum s. sacrospinosum et tuber- 

 osum) is an extensive quadrilateral sheet which completes the lateral pelvic wall. 



