FOEE EXTREMITY 



19 



As a matter of fact it is not formed by the shoulder, but by the arm, 

 and would be more appropriately designated the point of the arm. 



The Elbow. — The elbow marks the point of union of the arm above 

 with the forearm below. The point of the elbow is the summit of the 

 ulna or smaller of the two arm bones. From the prominence of this part 

 it stands exposed to injury, especially when the feet are allowed to grow 

 long or the heels of the fore-shoes are made to project beyond them, the 

 result being an inflammatory swell- 

 ing termed capped elbow. 



The Forearm. — The forearm 

 extends from the elbow-joint to the 

 knee. It is invested by muscles, 

 which act upon the bones below, 

 some carrying them forward (exten- 

 sors), others bending them back- 

 wards (flexors). The forearm com- 

 prises two bones, the radius and the 

 ulna. The point of the elbow, as 

 already explained, is formed by the 

 superior extremity of the latter. 



The Chestnuts or Castors.— 



The chestnuts or castors are small 

 horny excrescences of an ovoid or 

 elliptical form, situated on the inner 

 surface of the arm a little way 

 above the knee. They vary in size in 

 different breeds, and to a less extent 



in different animals of the same a, Scapula or shoulder Blade b. Humerus or 



Arm Bone. c, Ulna. D, Radius. E, Carpal 



breed. In coarsely-bred Cart-horses Bones, forming the Knee, 

 they reach their greatest dimensions, 



and sometimes grow outward like veritable horns, in which case they 

 are usually removed by the smith. The chestnuts are probably the re- 

 mains of a vanished hoof, which in the ancient horse invested a digit 

 corresponding to the thumb of man. 



The Knee. — The knee of the horse corresponds to the wrist of man. It 

 is formed \\\ two rows of small bones, which rest upon the metacarpal bones 

 below, and give support to the forearm above. The upper row comprises 

 four bones, and the lower one three. It is a joint of many parts, but al- 

 though complex in its structure its action is limited to the movements of 

 flexion and extension. Passing over it before and behind are some large 

 tendons, which are attached to the bones below and bring them into action. 



^e\\ 



Fig. 11. — Bones of Left Foreleg 



