3G-2 THE HUMERUS, OR LOWER BONE OF THE SHOULDER 



of the shoulder gives that direction to the collar which enables the horse 

 to act upon every part of it, and that inclination of the traces which will 

 enable his weight or power to be most advantageously employed. 



An impi'oved breed of our heavy draught-horses has of late years been 

 attempted, and with much success. Sufficient uprightness of shoulder is 

 retained for the purposes of draught, while a slight degree of obliquity has 

 materially quickened the pace and improved the appearance. 



Above its junction with the humerus, or lower division of the limb, the 

 shoulder-blade forms what is called the point of the shoulder. There is a 

 round blunted projection, best seen in the cut (p. 360). The neck of the 

 shoulder-blade there forms a shallow cavity, into which the head of the 

 next bone is received. 



The cavity is shallow because extensive motion is required, and because 

 both of the bones being so moveable, and the motion of the one connected 

 so much Avith that of the other, dislocation was less likely to occur. A 

 capsular ligament, or one extending round the heads of both bones, con- 

 fines them securely together. 



THE HUMERUS, OR LOWER BONE OF THE SHOULDER. 



Forming a joint with the shoulder-blade at the point of the shoulder is 

 the humerus. It is a short strong bone, slanting backward in an opposite 

 direction to the shoulder-blade. At the upper part it has a large round 

 head, received into the shallow cavity of the shoulder-blade, or as Mr. 

 Percivall has graphically described it, ' it is the segment of a globe, smooth 

 and pohshed, evidently for the purpose of playing like a spherical hinge 

 within the cup-like concavity occupying the place of the apex of the 

 scapula. There are no two bones in the skeleton whose articular connec- 

 tion is of a nature to admit more varied and extensive motion than exists 

 between the scapula and the humerus. If wc attempt to hft a horse's 

 fore-leg, we cannot merely bring it forward and carry it backward, but we 

 can also to a considerable extent make it perform a sort of rotatory motion, 

 in consequence of the mobihty existing in this joint between the socket of 

 the scapula and the head of the humerus.' It has sevei-al protuberances 

 for the insertion of 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, in order 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 already 

 stated, 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 very rare. The lower 

 bone of the shoulder and the shoulder-blade are by horsemen confoixnded, 

 together, and included under the appellation of the shoulder, and in com- 

 pliance with general usage Ave have described them as combining to form 

 the shoulder. This, however, is not correct, and Avill lead to error Avheu 

 Ave Avish to compare the fore-leg of the horse Avith the arm of man. In 

 man the arm, of Avhich the humerus is the bone, is perfectly free and 

 detached from the body ; in the horse it Hes in juxtaposition Avith the 

 chest, and is included in the integument covering the body : and this fact 

 has led to the error so commonly made of calling that part of the fore- 

 leg of the horse the arm, which is in reality the fore-arm, corresponding 

 Avith the fore-arm of man below the elbow. The knee as it is called, in 



