260 



THE HORSE. 



Still, on the inside of the thigh, and forming the posterior edge of the 

 tliigh inwards, and contributing niucii to its bulk, is anoliier of the 

 principal muscles of the thigh, y, proceeding from the first bones of the tail, 

 from the tuberosity of the ischium, and from the tendinous expansion 

 which we have described, and principally inserted into the upper and fore- 

 part of the upper bone of the thigh, but a portion of it going to the head of 

 the lower bone. That part which goes to the upper bone of the thigh acts 

 with very great mechanical advantage (see cut, p. 65), and most powerfully 

 bends the thigh on the pelvis, and lifts and extends the limb. It is one of 

 the most effectual of the extensor muscles. Considering the weight of limb 

 which it has to raise and extend, it had need to possess great power. At^ 

 is another muscle concerned in the same otiice. 



We now turn to some of the muscles which are very evident to the eye 

 on the outside of the thigh. 



CUT OF THE MUSCLES OF THE OUTSIDE OF THE THIGH. 



First is the outer G/utceus, 

 or buttock muscle, d, being 

 little more than a fleshy slip 

 attached to the muscle next to 

 be described. It rises as high 

 up as the spine. It runs along 

 the back part of the thigh in 

 the form of a ridge, and is 

 inserted into the smaller outer 

 prominence of the upper bone 

 of the thigh. Next is the 

 great gluimis muscle, arising 

 from the spinous and trans- 

 verse processes of several of 

 the bones of the loins, and 

 from the sacrum and from the 

 different edges of the ilium, 

 and inserted into the great pro- 

 tuberance of the upper bone 

 of the thigh (page 63). behind 

 and a little above the joint that 

 unites the thigh to the haunch- 

 bone. It is seen at c, in this 

 cut; constitutes the upper and 

 outer part of the haunch, and 

 gives that fullness and round- 

 ness to it, which good judges 

 so much admire in the quarters 

 of the horse. It is one of the 

 main instruments in progres- 

 sion. When the thigh has 

 been brouglit forward under the body by the muscles already described, 

 the p.ain action of these glutsei muscles is to extend the haunch, and force 

 or project the body onward. To effect this they must be very powerful, 

 and therefore they are so large, and rise from such an extensive surface; 

 and thev ought to act at great mechanical advantage, and so, in one sense, 

 they do; springing from the loins and ilium and the sacrum, they uc^ 



