STRUCTURE OF THE HOCK-JOINT. 241 



bably furnished to prevent it from being compressed by the 

 flexion of the hock. 

 ?/, 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 

 the pelvis, and becoming the main channel into which the 

 deep-seated veins of the hind extremity pour their 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 calciSf c, or 

 bone of the heel, and it projects upwards, flattened at the sides, 

 and receives into it the tendons of powerful muscles, which 



2l 



