. THE ARM. 237 



times the force, or 3G0 lbs., will be required, making- a difference in, or 

 savinir of muscLdur action, equal to 180 lbs. in each extension of the arm. 

 If a few pounds in the weig:ht of the rider tell so much for or a<i;ainst the 

 horse in a long; race, this saving' of power must make an almost incalculable 

 difference; and, therefore, judges of the horse rightly attach so much im- 

 portance 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 

 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 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 sliall be 

 justified in affirming that the addition of one-third to the length or projec- 

 tion of the elbow would be attended by a saving of one-half in the ex- 

 penditure 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 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 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 disap- 

 pear ; 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 ex- 

 tensive, 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 cc, 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 b, 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 be- 

 comes 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 front of 

 the shank-bone, tied down by 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 of the 



