356 



THE THIGH. 



its passage downward uniting with the last muscle, is inserted with it into the 

 inner and upper part of the tibia. It acts with great mechanical disad- 

 vantage, but its power is equal to the task. It bends the leg and rotates it inward. 



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

 inwards, and contributing much to its bulk, is another important muscle, the 

 pectineus. Part of it acts with very great mechanical advantage, and power- 

 fully flexes the thigh on the pelvis, and lifts and bends the leg. It is one of 

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

 which it has to raise and flex, it had need to possess great power. 



We now turn to some of the muscles that are evident to the eye on the out- 

 side of the thigh. 



CUT OF THE MUSCLES OF THE OUTSIDE OF THE THIGH. 



First is the glutaut externut, 

 situated in the middle of the 

 external part of the haunch. Itisof 

 a triangular figure, attached to the 

 antero-superior and to the inferior 

 spines of the ilium, and is inserted 

 into the smaller outer prominence 

 of the upper bone of the thigh. 

 Next is the great gluteus 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 

 108;, behind and a little above the 

 joint that unites the thigh to the 

 haunch-bone. It is seen at c, in 

 this cut. It 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 in- 

 struments in progression. When 

 the thigh has been brought for- 

 ward under the body by the mus- 

 cles already described, the plain 

 action of these glutei 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. They ought, also, to act at great mechanical advantage, 

 and so, m one sense, they do. Springing from the loins and the ilium and the 

 sacrum, they act almost in a right, or perpendicular line; in that line in which 

 we have seen that the greatest power is gained: 



There is another and smaller glutanis muscle under that which has been last 

 described, arising likewise from the back of the ilium, inserted into the same 

 protuberance of the thigh-bone, and assisting in the same office. It is not 

 visible in the cut. 



These muscles, as Mr. Percivall well explains it, are extensors either 



