68 



THE ANATOMY OF THE HORSE. 



It is a comparatively small muscle, with coarse fasciculi having a slightly 

 spiral direction. It fu-ises from the rough lines on the gluteal surface of 

 the shaft of the ilium just above the cotyloid cavity, and from the supra- 

 cotyloid ridge (superior ischiatic spine). It is inserted to the inner side 

 of the convexity of the great trochanter. 



Action. — It is an abductor and inward-rotator at the hip-joint. 



The Obturatou Ixternus and the Pyriformis (Plate 16, and fig. 2) 

 are two muscles arising within the pelvis, the former taking ori(/in from 

 the bone around the obturator foramen, and the latter from the pelvic 

 surface of the ilium. They have a common tendon, which emerges 

 from the pelvis by the lesser sacro-sciatic opening, where it plays over 

 a smooth portion on the external border of the ischium. The tendon 

 is inserted into the trochanteric fossa. 



Action. — To produce outward rotation at the hip. 



The Gemelli. In Plate 16 a bundle of muscular fibres is seen at 

 each edge of the above-mentioned common tendon. If this common 



Fig. 2. 



Muscles of the Tail, deep Muscles ok the Hip, and Pelvic Lujaments (Chaui-eav.). 



1. Erector coccygie ; 2. Curvator coccygis ; 3. Depressor coccygis ; 4. Compressor coccygis 

 .1. Deep ghiteus ; 6. Rectus parvus ; 7. Common tendon of obturator internus and pyriformis 

 S. Gemelli ; !». Accessory fasciculus of the fame ; 10. Qtiailratus femoris; 11. Sacro-sciatic ligament 

 12. Great sacro-sciatic foramen ; 13. Superior ilio-sacral ligament ; 14. Inferior ilio-sacral ligament. 



tendon be cut where it appears at the lesser sciatic opening, and raised 

 outwards, what previously seemed two distinct muscular bundles will 

 now be seen to be the edges of a single flattened muscle, which arues 

 from the ischium below and at the edges of the smooth surface for the 



