THE LOWER BONE OF THE SHOULDER. 



235 



into the tendinous substance covering the 

 muscles of the fore-arm, and reaching a 

 considerable way down the arm. The 

 use of this muscle is obvious and impor- 

 tant. It binds the arm to the side of the 

 horse ; it keeps the legs straight before 

 the horse when he is at speed, that the 

 weight of the body may be received on 

 them in a direction most easy and safe to 

 the horse and to the rider, and most 

 advantageous for the full play of all 

 the muscles concerned in progression. 

 Considering the unevenness of surface 

 over which a horse often passes, and 

 the rapid turnings which are sometimes 

 necessary, these muscles have enough to 

 do : and when the animal is pushed be- 

 yond his strength, and these muscles are 

 wearied, and the fore-legs spread out, 

 and the horse is " all abroad," the con- 

 fused and unpleasant manner of going, 

 and the sudden falling off in his soeed, are 

 well known to every rider. 



THE LOWER BONE OF THE SHOULDER. 



Fornsing a joint with the shoulder-blade at the point of the shoulder 

 I ihe humerus, or lower bone of the shoulder (J. p. 63, and p. 230). It is 

 a short, strong bone, slanting backward in an opposite direction to the 

 s joulder-blade. At the upper part it has a large round head, received 

 into the shallow cavity of the shoulder-blade. It has several protuberances 

 for the insertion of the muscles, and is terminated below by two condyles 

 or heads, which in front receive the principal bone of the arm between 

 them as in a groove, thus adding to the security and strength of the joint, 

 and limiting the action of this joint, and of the limb below, to mere bending 

 and extension, without any side motion. Farther behind, these heads 

 receive the elbow deep between them, to give more extensive action to the 

 arm. In a well-formed horse this bone can scarcely be too short, in order 

 that the fore-legs may be as forward as possible, for reasons at which we 

 have already glanced ; and because, when the lower bone of the shoulder 

 is long, the shoulder must be too upright. Dislocation can scarcely occur 

 in either of the attachments of the bone, and fracture of it is almost 

 impossible. The lower bone of the shoulder, and the shoulder-blade, are 

 by horsemen confounded together, and included under the appellation of 

 the shoulder, and in compliance with general usage we have described them 

 as combining to form the shoulder; yet it would be well for the reader. to 

 always bear in mind the distinction. 



Among the muscles arising from the lower bone of the shoulder, are tv/o 

 •short and very strong ones, seen at the lower r and s, the first proceeding 

 from the upper part of this bone to the elbow, and the second from the 

 internal part, and likewise going to the elbow, and both of them being 

 powerful agents in extending the leg. 



In front, at y, is one of the muscles of the lower bone of the shoulder, 

 the external one, employed in bending the arm ; rising from the inner 



