280 THE HIND LEGS. 



cannot be the concussion to which the fore legs are exposed (for the weight of the 

 body is never thrown violently upon them), yet in the powerful action of these limbs 

 there is much strain on the joints, and we shall, therefore, find that there are, in all 

 of them, admirable provisions against injury. The head of the upper bone of the thigh 

 is received into a deep cup (the acetabulum), by which it is surrounded on every side, 

 and dislocation from which would seem almost impossible. But the bony cup may 

 "•ive way 1 Not so, provision is made against this. All three of the haunch-bones 

 unite in the formation of this cup, and the sutures by which they are held together are 

 of such a nature, that, generally speaking, no shock, or exertion, or accident, can dis- 

 unite them. There is even something more in order to make the attachment doubly 

 sure. In addition to the usual capsular and other ligaments, a singularly strong one 

 rises from the base of the cup, and is inserted into tlie head of the thigh-bone, seeming 

 as if it would render separation or dislocation altogether impossible. Such, however, 

 is the strange power of the muscles of the hind limbs, that, with all these attach- 

 ments, sprain of the ligaments of the thigh, or the round bone, as horsemen call it, and 

 even dislocation of it, are occasionally found. 



The thio-h-bone is both the largest and strongest in the frame. It is short and 

 thick, and exhibits the most singular prominences, and roughnesses, and hollows, for 

 the insertion of the immense muscles that belong to it. Four prominences, in particu- 

 lar, called by anatomists trochunttrs, two on the outside, one on the inside, and one 

 near the head of the bone, aftord attachment to several important muscles. The head 

 of the bone is placed at right angles with its body, by which this important advantage 

 is gained, that the motion of the thigh-joint is principally limited to the act of bending 

 and extending, although it possesses some slight lateral, and even some rotatory action. 

 The lower head of the thigh-bone is complicated in its form. It consists of two 

 prominences, which are received into corresponding depressions in the next bone, 

 and a hollow in front, in which the bone of the knee or stifle plays as over a perfect 

 pulley. 



A short description of the muscles of the hinder extremities may not be uninterest- 

 ing to the horseman. The next cut will contain a few of them. 



The muscles of the hinder extremity are more powerful than those of any other 

 part of the frame ; therefore an extraordinary provision is made to confine them in 

 their respective situations, and thus contribute to their security and strength. When 

 the skin is stripped from any part, we do not at once arrive at the muscles, but they 

 are thickly covered by a dense, strong, tendinous coat, intended to confine them to 

 their places. This membrane, called the fascia, is of extraordinary strength in the 

 hind quarter, and reaches over the whole of the haunch and thigh, and only ceases 

 to be found at the hock where there are no muscles to be protected. If the power of 

 the muscles is sufficient to dislocate or fracture the thigh-bone, they need the support 

 and confinement of this tendinous coat. When this tendinous band is dissected off, 

 another is found beneath, which is represented at u, in the cut at p. 281, raised and 

 turned back, larger than the former, thicker and more muscular. It proceeds from the 

 haunch-bones to the stifle, upon tlie fore and outer part of the haunch and thigh, and 

 is intended to tighten and strengthen the other. 



Under the part of this flat and binding muscle, which is represented in our cut as 

 raised from its natural situation, is a large round one, proceeding from the ilium, not 

 far Irom the cup which receives the upper bone of the thigh, and running straight 

 down this bone, and thence its name rectus. It is inserted into the bone of the stifle. 

 An inspection of the cut, p. G8, will show that it is so situated as to be enabled to 

 exert its great power in the most advantageous way. It is a very ]irominent muscle, 

 and possesses immense strength. It terminates in a tendon, which is short and very 

 strono-, and which is, before its insertion into the patella, united with the prolongation 

 of the tendinous substance at sx, in the cut, p. 282, and also with the tendon of the 

 muscle at i, in that cut, and at c, in that on page 281, and which is properly called 

 vastus, from its great hulk. Some have divided this into two nuiscles : the external 

 and internal. The external arising from the outer surface of the upper bone of the 

 thiffh; the internal, from the inner surface; and they are inserted into the upper part 

 of Ihe bone of the stifle, both on the inner and outer side. These muscles act at 

 considerable mechanical disadvantage. They form a very slight angle, not at all 

 approaching to a right angle ; but they are muscles of immense size, and occupy all 

 the fore pari of the thigh,"from the stifle upwards. They are powerful extensors of 



