DISEASES OF CATTLE 445 



Should this accident occur more than once it is a good practice 

 to apply a blister around the joint, as in the formula recommended 

 for sprain of shoulder, and observe the precautions as to restraint 

 and subsequent treatment there recommended. With this one excep- 

 tion, dislocations in the ox occurring independently of other compli- 

 cations are rare. 



Dislocation with fracture may occur in any of the joints, and 

 where one is suspected or discovered, examination should always be 

 made for the other before treatment is applied. When a fracture oc- 

 curs in the vicinity of a joint the force sufficient to rend the bone is 

 likely to be partly exerted on the immediate tissues, and when the 

 bone gives way the structures of the joints are likely to be seriously 

 injured. It occasionally happens that the injury to the joint be- 

 comes the most important complication in the treatment of a frac- 

 ture. In order clearly to understand the reason for this a few words 

 are necessary in relation to the structure of the joints. 



The different pieces constituting the skeleton of the animal body 

 are united in such a manner as to admit of more or less motion one 

 upon another. In some of the more simple joints the bones fitting 

 one into another are held together by the dense structures around 

 them, admitting of very little or no movement at all, as the bones of 

 the head. In other joints the bones are bound together by dense car- 

 tilaginous structures, admitting of only limited motion, such as the 

 union of the small bones at the back part of the knee and hock 

 (metacarpal and metatarsal). In the more perfect form of joint the 

 power of motion becomes complete and the structures are more com- 

 plex. The substance of the bone on its articular surface is not cov- 

 ered with periosteum, but is sheathed in a dense, thin layer of carti- 

 lage, shaped to fit the other surfaces with which it comes in contact 

 (articular). This layer is thickest toward its center when covering 

 bony eminences, and is elastic, of a pearly whiteness, and resisting, 

 though soft enough to be easily cut. The bones forming an articula- 

 tion are bound together by numerous ligaments attached to bony 

 prominences. The whole point is sealed in by a band of ribbon-like 

 ligament (capsular ligament) extending around the joint and at- 

 tached at the outer edge of the articular surface, uniting the bones 

 and hermetically sealing the cavities of the articulation. This struc- 

 ture and the articular surface of the bone is covered by a thin, deli- 

 cate membrane, known as the synovial membrane, which secretes the 

 joint oil (synovia) . This fluid is viscid and colorless, or slightly yel- 

 low, and although it does not possess a large amount of fat, its char- 

 acter somewhat resembles oil, and it serves the same purpose in lubri- 

 cating the joints that oil does to the friction surface of an engine. 

 Although the tissues of the joint when used in a natural way are able 

 to withstand the effect of great exertion, when unnaturally used, as 

 they are very delicate and complex, they are liable to inflammatory 

 and other changes of a very serious nature. The synovial membrane, 

 and in fact the whole structure of the joint, is susceptible to injury 

 and serious inflammatory derangement, and the capsular ligament is 

 liable to be distended from excessive secretion of synovia. The lat- 



