THE ARM. 237 



times the force, or 360 lbs., will be required, making a difference in, or 

 saving of muscular action, equal to 180 lbs, 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^.ong race, this saving of power must make an almost incalculable 

 dilTerence; 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, we proved 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 mani- 

 festly 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 we add 

 this advantage from the direction in which the power is applied to that 

 which we gain from the increased length of the bone, we shall be justified 

 in affirming 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 we might have easy but confined 

 action. There must be harmony of proportion in the different parts of 

 tiie 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 be placed in the hands 

 of a skilful veterinarian, although the chances of cure are certainly against 

 the horse, yet the owner need not despair. Absolute and long-continued 

 rest, and that produced by means of a sling, will be indispensable. 



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 be passed 

 through the tumour, it will sometimes rapidly diminish, and even disappear; 

 but if it be of considerable magnitude, the skin should be slit open 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 inflammation 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. page 233, is the principal one, called the extensor of the leg; it is of 

 considerable bulk, and occupies the front part of the arm. It arises from 

 the lower part of the body of the lower bone of the shoulder, and from its 

 outer head. As it descends down the arm, it becomes tendinous ; the tendon 

 passes under one of the ligaments of the knee ; it then spreads out, and is 

 inserted into the fore and upper part of the shank bone. It is also seen at 

 h, page 235. 



The next muscle in situation and importance is seen at w, and called the 

 extensor of the foot. It rises from the outer head of the lower bone of the 

 shoulder, and likewise from the outer head of the bone of the arm. "It 

 becomes tendinous as it proceeds, and passes under a strong ring at the 

 knee, by which it is confined in its proper situation ; it then runs along the 

 f'ont of the shank-bone, tied down by a strong cellular substance; passes 

 over the fetlock, and part of the upper pastern; is inserted into the lower 

 part of the upper pastern, into the lower pastern, and the coffin-bone or bone 



