370 SPLINT. 



upper liead of tlie larger pastei'n, and are so enclosed and guarded by the 

 elevated edges of that bone, that when the sliank-bone and pastern are 

 fitted to each other, they form a perfect hinge. They admit of the bend- 

 ing and extension of the limb, but of no lateral or side motion. This is 

 a circumstance of very great importance in a joint so situated, and having 

 the whole weight of the horse thrown upon it. 



The smaller bones are placed behind the larger ones on either side. A 

 slight projection of the head of each can alone be seen in front. The 

 heads of these bones are enlarged, and receive part of the weight con- 

 veyed by the lower row of the bones of the knee. They are united to the 

 larger bone by the same kind of substance which is found in the colt be- 

 tween the bone of the elbow and the main bone of the arm ; and which is 

 designed, by its great elasticity, to lessen the concussion or jar when the 

 ■weight of the animal is thrown on them. They reach from one half to 

 two thirds of the length of the shank-bone, and, through their whole extent, 

 arc united to it by this substance ; but, as in the elbow, from the animal 

 being worked too soon or too \dolently, bony matter is deposited in the 

 room of the ligamentous, and a bony union takes place instead of 

 the natural one. There is no doubt that the ease of motion is somewhat 

 lessened by this substitution of bone, but other elastic principles are 

 probably called into more powerfal action, and the vakie of the horse is 

 not perceptibly impaired, although it is hard to say what secret inju:y 

 may be done to the neighbouring joints, and the cause of which, the 

 lameness not appearing until a distant period, is not suspected. 



In this process, however, mischief does often immediately extend to the 

 neighbouring parts. The disposition to deposit bone, reaches beyond the 

 circumscribed space between the larger and smaller bones of the leg, and 

 a tmnour, first callous, and afterwards bony, is found, ■with part of its 

 base resting on the line of union between these bones. This is called a 



SPLINT. 



The splint is generally found on the outside of the small bones, and fre- 

 quently on the inside of the leg. "Wliy it should appear on the outside ot 

 the small bones it is difficult to explain, except that the space between 

 these bones is occupied by an important mechanism, which will be 

 presently described ; and, as in the case of abscess, a natural tendency 

 was given to them to determine outward, that ■vital parts might not be 

 injured. The cause of their almost exclusive appearance on the inside 

 of the leg admits of easier explanation. The inner splint-bone is placed 

 nearer the centre of the weight of the body than the other, and, from the 

 nature of its connection with the bones of the knee, actually receives more 

 of the weight than does the outer bone, and therefore is more liable to 

 injury, from the jar and concussion occasioned by the action of the horse 

 with a superadded weight above, and harsh unyielding roads below, inflam- 

 mation is set up, and this consequent deposit of bony matter. The inner 

 bone receives the whole of the weight transmitted to the small bone of 

 the knee. It is the only support of that bone. A portion only of one of 

 the bones rests on the outer splint-bone, and the weight is shared between 

 it and the shank. In addition to this there is the absurd practice of many 

 smiths of raising the outer heel of the shoe to an extravagant degree, 

 wliich throws still more of the weight of the horse on the inner splint- 

 bone. Bony tumours occasionally appear on other parts of the shank-bone, 

 being the consequence of ■violent blows or other external injuries, and are 

 commonly called splints. 



When the splint of cither sort is forming, the horse is frequently lame, 

 for the periosteum or membrane covering the bone is painfally stretched 



