68 



THE ANATOMY OF THE HORSE. 



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

 spiral direction. It arisen 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 Obturator Internus and the Pyriformis (Plate 16, and fig. 2) 

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

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

 surface of the ilium. The}' have a common tendon, which emerges 

 from the pelvis liy 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 Ge.melli. In Plate 16 a bundle of muscular fibres is seen at 

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





'7f 



O:- 



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Fi(5. 2. 

 Muscles of the Tail, deep Muscles of the Hip, asd PEL^■lc Hoamen'ts (Cho.u-cmv). 

 1. Erector coccygis; 2. Ciirvator coccygis ; 3. Depressor coccygis ; 4 Comnressor coccygia ■ 

 «■ ?e3l?/ ^A- '• ^'' "' -'"'^''-n I- C™""""! tendon of obturator inteinu^'an 1 pyrifoS■ 

 ?2 G^ft sacratcttrSrlmer'^r^ **"' '™-'^ ■' '"■ Q;-^'™*"'^'^"''"''- "• Saoro-seiatiiiiganS; 

 li. threat sacro-scidtic foramen , 13. Superior ilio-sacral ligament ; 14. Inferior ilio-sacral li<fanient. 



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

 outwards, what previously seemed two distinct muscular >mndles will 

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

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



