THOROUGH-PIN— THE HOCK. 265 



principal nerves on the fore-part of the inside of the thi^h pursue their 

 course at t, in the direction of the cutaneous vein ; and those of the pos- 

 terior part are seen at s, and at u are those important ligamentous bands at 

 the bending of the hock which confine the tendons. 



In the cut of the outside of the thigh, page 260, j) will give the course 

 of the anterior arteries and veins ; q the course of the principal nerires, 

 and coming into sight below ; and r the bands described in the former 

 plate. 



Also, in the cut of the outside of the shoulder and arm, p. 233, the figures 

 1, 2, and 3, designate the places of the principal artery, nerve, and vein 

 of the le"-; 4 gives the subcutaneous vein running within the arm ; and 5, 

 the subcutaneous vein of the side of the chest. 



In the cut of the inside of the arm, p. 235, the lines above represent, in 

 the order from the front, the principal nerves, arteries, and veins of the 

 shoulder and arm, and, on the muscles, k gives the principal subcutaneous 

 vein of the inside of the arm, and i tlie artery by which it is accompanied. 



The stifle joint is not often subject to sprain. The heat and tenderness 

 will guide to the seat of injury. Occasionally, dislocation of the patella 

 has occurred, and the horse drags the injured hmb after him, or rests 

 it on the fetlock ; — the aid of a veterinary surgeon is here requisite. The 

 muscles of the inside of the thigh, generally, have sometimes been sprained : 

 this may be detected by diffused heat, or heat on the inside of the thigh 

 above the stifle ; — rest, fomentations, bleeding, and physic, will be the proper 

 means of cure. 



THOROUGH-PIN. 



We have observed that there are placed in the neighbourhood of joints, 

 certain bags, containing a mucous fluid for the purpose of lubricating the 

 parts, and that these sometimes become inflamed and enlarge. We have 

 spoken of wind-galls and their treatment. A similar enlargement is found 

 above the hock, between the tendons of the flexor of the foot, and the ex- 

 tensor of the hock. As from its situation it must necessarily project on 

 both sides of the hock, in the form of a round swelling, it is called a 

 thoroi/gh-piJi, a, p. 262. It is an indication of considerable work, but, 

 except it be of very great size, it is rarely attended by lameness. The 

 mode of treatment must resemble that recommended for wind-galls. 

 Although thorough-pin cannot be pronounced to be unsoundness, yet it 

 behoves the buyer to examine well a horse with thorough-pin, and to ascer- 

 tain whether undue work may not have injured him in other respects. 



THE HOCK. 



We now arrive at a very important joint, often the evident, and much 

 oftener the unsuspected seat of lameness, and the proper formation of 

 which is essentially connected with the excellence and value of the horse. 

 We shall describe it a little at length. 



The inferior head of the tibia is formed into two deep grooves, with 

 three sharpened ridges, one separating the grooves, and the other two 

 forming the sides of them. It is seen at a in the following cut. It 

 rests upon a very singular bone, b, called the astragalus (shaped like 

 the die or dice used by the ancients), which has two circular risings 

 or projections, and with a depression between them, answering exactly 

 to" the irregularities of the tibia, and these are received and morticed into 

 each other. At the posterior part its convex surface is received into a 



