340 SPLINT. 



guarded by the elevated edges of that bone, that when the shank-bone and the 

 pastern are fitted to each other, they form a perfect hinge. They admit of the 

 bending 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 conveyed 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 between 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, are united to it by this substance ; but, as in the 

 elbow, from the animal being worked too soon, or too violently, inflammation 

 ensues 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 powerful action, and the value of the 

 horse is not perceptibly impaired, although it is hard to say what secret injury 

 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 cir- 

 cumscribed space between the larger and smaller bones of the leg, and a 

 tumour, first callous, and afterwards bony, is found, with part of its base rest- 

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



SPLINT. 



The splint is invariably found on the outside of the small bones and generally 

 on the inside of the leg (c, p. 351). Why it should appear on the outside of 

 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 de- 

 scribed ; 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 connexion with the 

 bones of the knee, actually receives more of the weight than does the outer bone, 

 and therefore is more liable to injury, and inflammation, and this consequent 

 deposit of bony matter. The inner bone receives the whole of the weight trans- 

 mitted 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, 

 which 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 conse- 

 quence of violent blows or other external injuries, and are commonly called splints. 



When the splint of either sort is forming, the horse is frequently lame, for the 

 periosteum or membrane covering the bone is painfully stretched ; but when this 

 membrane has accommodated itself to the tumonr that extended it, the lameness 

 subsides, and altogether disappears, unless the splint be in a situation in which it 

 interferes with the action of some tendon or ligament, or in the immediate neigh- 

 bourhood of a joint. Pressing upon a ligament or tendon, it may cause inflamma- 



