STRUCTURE OF THE HOCK-JOINT. 
241 
bably furnished to prevent it from being compressed by the 
flexion of the hock. 
y, y. The large cutaneous vein, or vein immediately under the skin. 
z. The inguinal vein, which is one of rather large size, coming 
from the groin, which owes its formation to a considerable 
branch emanating from the muscles of the thigh, and the above 
superficial or cutaneous abdominal vein. The femoral vein is 
the continuation of the external iliac trunk below the brim of 
ihe pelvis, and becoming the main channel into which the 
deep-seated veins of the hind extremity pour iheir blood 
STRUCTURE OF THE HOCK-JOINT. 
PLATE VIII. Fig. 1. 
This is one of the most important points of the animal, 
and which ought to be thoroughly known by all who possess 
a horse. We are convinced that this is much more fre¬ 
quently the seat of disease, and lameness then is suspected. 
Besides, upon the proper formation of this joint, the value 
and excellence of the horse chiefly depends. 
As the knee answers to the wrist of man, and is therefore 
analogically regarded as the carpus, so in like manner the 
hock becomes the correspondent part to the instep, and is 
consequently considered under the technical appellation of 
tarsus. It consists of six small bones. 
a. The astragalus, or knuckle-bone. Its form is like that of a pulley 
Its surface consists of two bold semicircular prominences, with 
a deep capacious groove between them; these are admirably 
adapted to the two grooves, parted by their middle projection 
in the lower extremity of the tibia, and these opposite promi 
nences and grooves are received, and as it were morticed into 
each other. At the posterior part its convex surface is received 
into a concavity near the base of another bone, and with which 
it is united by very strong ligaments to the os calcis, c, or 
bone of the heel, and it projects upwards, flattened at the sides, 
and receives into it the tendons of powerful muscles, which 
