ii62 THE FORE LEGS. 



there will natnrally be a large and muscular arm, and such a formation of the limb, 

 and particularly of the elbow, as will enable these muscles to act with most advantage. 



The principle of the lever (referred to at p. 257) is here beautifully applicable. 

 The elbow-joint is the centre of motion; the whole of the lower part of the leg is the 

 weight to be raised ; and the power by which it is to be raised in one act of progres- 

 sion, the extending of the limb, is the muscles inserted into the elbow. In proportion 

 as the weight is more distant than the power from the centre of motion, as it is in the 

 construction of this limb, so will be the greater degTce of energy requisite to be exerted. 

 Supposing that the weight, taking the knee to be the centre of it, is eighteen inches 

 from the elbow-joint — that the limb weighs GOlbs., and that the elbow projects two 

 inches from the joint — then an energy equal to nine times the weight, or 540lbs., will 

 be needed to move and extend the limb, because the weight is nine times farther from 

 the centre of motion than the power is. If in another horse the point of the elbow 

 projects three inches from the joint, the weight of the leg remaining the same, only 

 six times the force, or SGOlbs., will be required, making a difference in, or saving of, 

 muscular action, equal to ISOlbs. in each extension of the arm. If a few pounds in 

 the weight of the rider tell so much for or against the horse in a long race, this saving 

 of power must make an almost incalculable difierence ; and therefore, judges of the 

 horse rightly attach so much importance to the depth of the elbow, or the projection 

 of the point of the elbow from the joint. 



When describing the proper obliquity of the shoulder, it was stated that the power 

 was exerted with most advantage in a line perpendicular to the arm of the lever, and 

 that the slightest deviation from that line was manifestly disadvantageous. If the 

 reader will examine the cut, he will perceive that muscles from the shoulder and the 

 bone of the arm take a direction much nearer to a perpendicular line in the long than 

 in the short elbow, and therefore act with proportionably greater advantage ; and if this 

 advantage from the direction in which the power is applied to that which we gain 

 from the increased length of the bone is considered, it will be plain that the addition 

 of one-third to the length or projection of the elbow would be attended by a saving of 

 one-half in the expenditure of muscular power. There is, however, a limit to this. 

 In proportion as the elbow is lengthened, it must move over a greater space in order 

 to give the requisite extension to the limb ; and consequently the muscles which act 

 upon it must be lengthened, otherwise, although the action might be easy it would 

 be confined. There must be harmony of proportion in the ditferent parts of the limb, 

 but a deep elbow, within a certain range, is always connected with increased power 

 of action. 



The elbow is sometimes fractured. If the animal is placed in the hands of a skilful 

 veterinarian, although the chances of cure are certainly against the horse, yet the 

 owner needs not to despair. The treatment of fracture of the elbow-joint will be con- 

 sidered in its proper place. 



Enlargements sometimes appear about the elbow, either the consequence of a violent 

 blow, or from the calkins of the shoes injuring this part when the horse sleeps with 

 his legs doubled under him. If a seton is passed through the tumour, it will some- 

 times rapidly diminish, and even disappear; but if it is of considerable magnitude, 

 the skin should be opened along the middle of the swelling, and the tumour dissected 

 out. 



The elbow-joint is sometimes punctured, either accidentally, or through the brutality 

 of the groom or carter. The swelling is often rapid and extensive, and fatal inflam- 

 mation may ensue. Rest, and the closure of the wound, are the most important 

 considerations. 



There are other muscles of the fore-arm employed in extending the limb. At x, 

 cage 259, is the principal one, culled the extensor mdacarpi. It is attached superiorly 

 .0 the outer and fore jiarts of the external condyle of the humerus, and also to the 

 capsular ligament, and inferiorl}' to the antero-superior part of the great metacarpal 

 i)one. Its superior attachments are jnincipally fleshy, with a few tendinous fibres 

 interposed. These diminish towards tlio centre, but a little lower down is a tendon, 

 roun<l at its origin, but gradually growinir flat and expanding in breadth towards its 

 termination. Its office is to extend the Irnr. 



The next muscle in situation and importi^nce is seen at v\ and called the extensor 

 pedis. It rises from the fore part of the external condyle of th(! humerus, and pursues 

 its course down the leg, and expanding nlVr it has passed the fetlock, it serves the 



