264 THE HORSE. 



it is tied down in its place, within which it plays. It is seen conti- 

 nuing- its course on the front of the cannon or shank bone. Having 

 arrived at the fetlock joint, it begins to expand, and is finally inserted into 

 the tipper part of the coffin-bone, or bone of the foot, after having given 

 various fibres to both the pasterns. The course of the corresponding ten- 

 don in the fore-leg is given in the cut, p. 249, fig. I. 



At m, p. 260, is another of the extensor muscles, called the jyeroiicsus, 

 from a name given to the fibula. It arises from the whole course' of the 

 fibula, and also becomes tendinous before it reaches the hock. About half 

 ■way down the shank it is found in the same sheath with the principal 

 extensor muscle, and is inserted with it into the coffin-bone. The office 

 of the extensor muscles is to raise the foot from the ground, and to bring 

 it forward under the body. 



At o is ihe flexor j)edi!i, one of the principal flexor (bending) muscles 

 of the foot, arising from the upper part of the tibia. As it approaches the 

 hock it is distinguished by its large round tendon, which is seen to enter 

 into a groove at the back of the hock. It is continued down the back of 

 the leg like a similar muscle in the fore-leg, is the perforating flexor 

 muscle of the hind-leg, and assists in bending the pastern and coffin 

 oints. 



A: is a very slender muscle, arising from the head of the fibula, and pro- 

 ceeding over the external part of the thigh, and, just above the hock, 

 uniting with the tendon of the perforating muscle. 



J is a very powerful muscle, springing from the head of the upper bone 

 of the thigh, and, midway down the lower bone of the thigh, ending in a 

 flat tendon, which is inserted into the point of the hock. Its use is to 

 extend the hock. It is evidently most advantageously situated for powerful 

 action ; for it acts almost at right angles, and its effect is increased in pro- 

 portion to the projection of the point of the hock. 



We will now turn to the inner side. See cut, p. 259. 

 m gives a portion of the muscle which we have just described. 

 71 an inside view of the perforating flexor muscle of the foot. 

 I is the peronseus. 



o is the perforated flexor tendon, having its origin from near the lower 

 head of the upper bone of the thigh ; becoming tendinous as it passes down 

 the thigh ; expanding over and surrounding the point of the hock, and 

 assisting in extending it ; and then pursuing its course down the posterior 

 part of the leg, in a manner so much resembh'ng that of similar tendons in 

 the fore-leg, that we shall content ourselves with referring to a description 

 of the perforated and perforating flexor tendons at page 239. 



At e is a continuation of the gracilis muscle, p. 259, over the stifle. 

 At h\^ the extensor pedis already described, p. 263, with its tendon." ' 

 At f is a muscle used to bend the hock, the^e^or metatarsi, or bender 

 of the leg ; arising from the lower part of the upper bone of the thigh, and 

 inserted into the upper part of the shank-bone ; and also the inner small 

 splint-bone. It is a muscle of considerable power, although disadvan- 

 tageously situated, both as to its direction and its being inserted so near to 

 the joint. 



At k is a short muscle extending from the upper to the lower thigh- 

 bones (the pojjlitceus), bending the stifle and turning the limb inward. 



These cuts represent the situation of some of the principal blood-vessels 

 and nerves of the hind extremities. 



In the cut of the inside of the thigh, page 259, p represents the course 

 of the principal artery ; at q are blood-vessels belonging to the groin ; at 

 r is the large cutaneous vein, or the vein immediately under the skin. The 



