260 



The horse. 



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

 thigh inwards, and contributing much to its bulk, is another of the 

 principal muscles of the thigh, /, proceeding from the first bones of the taily 

 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 g is another muscle, concerned in the same office. 



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

 on the outside of the thii'h. 



CUT OF THE MUSCLES OF THE OUTSIDE OF THE THIGH. 



First is the outer GhdcBus-^ 

 or buttock muscle, d, being- 

 little more than a fleshy slip 

 attached to the muscle next to 

 be described. It arises as hig'h 

 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 glutcsiis 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 

 protuberance 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 fulness and 

 roundness to it, which good 

 judges so much admire in the 

 quarters of the horse. It is 

 one of the main instruments 

 in progression. When the 

 thigh has been brought for- 

 ward under the body by the muscles already described, the plain action 

 of these glutaei muscles is to extend the haunch, and force or project the 

 body onward. To effect this they must be very powerful, and tlierefore 

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

 to act at great mechanical advantage, and so, in one sense, they do i 

 springing from the loins and ilium and the sacrum, they act almost in a 



