BONE-SPAVIN. 219 



ridges, exactly corresponding with the grooves of the bone 

 above; also, behind this latter bone, the bone above rests 

 against another bone, called the os ccdcis, (spur-like bone), 

 which projects upward and backward, and forms the promi- 

 nence to which the hamstring is attached. This joint admits 

 of very free hinge motion, but of no side motion. It is the 

 hough-joint j^roper. These two bones rest on the flat or irreg- 

 ularly concave surfaces, or upper sides of two other bones, 

 the cuhoides (or cube-bone) behind, and the larger cuniform 

 (or wedge-shaped) bone in front. The larger wedge-shaped 

 bone rests on two other smaller wedge-shaped bones. The 

 cube-shaped bone rests on the head of the outer sj)lint-bone 

 and part of the head of the cannon or shank-bone. The 

 smaller wedge-bone rests almost entirely on the inner splint- 

 bone, and the middle wedge-bone entirely on the head of the 

 cannon-bone. These joints admit of but little motion, excej^t 

 the hough-joint proper, as we have seen. They are bound 

 together by very strong ligaments, and between their points 

 of contact are lined Avith elastic cartilages covered with the 

 synovial membrane, which furnishes the joint-oil to these 

 many joints. The object of this arrangement seems to be to 

 prevent concussion. The splint-bones are attached to the 

 cannon-bone by firm cartilage ; they are placed behind it, one 

 toward each side ; they have a head, but terminate in a point 

 about half-way down the cannon-bone. 



From the causes, w^hich will presently be explained, inflam- 

 mation is excited in the cartilage which unites the splint-bone 

 with the shank or cannon-bone; the cartilage commences to 

 become ossified or turned into bone; and, finally, the union 

 between the two bones is changed from the yielding or elastic 

 cartilaginous character to a firm, bony union, precisely of the 

 same character of splint on the fore-leg. This uniformly 

 takes place on the inner splint-bone, but the formation of bony 

 deposit does not stop here. Having once commenced, and the 

 causes still continuing to operate, a hard tumor will be ob- 



