360 SPRAIN OF THE FETLOCK-JOINT. 



pensory to be deprived of action, the fetlock would lose its spring- 

 like play while the horse was going : thus, either structure may 

 suffer deprivation of function and consequent derangement from 

 disease of the other. 



Owing to this duplicate structure and function of the fetlock, 

 there may be said to be 



Two Kinds of Sprain of this Joint and its Appurte- 

 nances : one in which the tendons are the parts mainly involved ; 

 the other, in which the posterior, sesamoid, and suspensory division 

 suffer the most : the former occurring more in the fore legs ; the 

 latter in the hind. When a horse is sprained in the fore fetlock, 

 we frequently find the swelling and heat more in the anterior 

 parts than in the posterior ; very often, indeed, there exists full- 

 ness in the site of the extensor tendon, as well as around the joint, 

 giving the horse the appearance of " knuckling over." On the 

 other hand, when the hind fetlock has sustained sprain, we usually 

 perceive that the posterior parts of the joint are swollen and 

 heated, to the entire absence of any thing similar upon the front 

 parts. This arises from the difference in function — in progression 

 — between the fore and hind extremities ; on which, as I have so 

 lately written*, I shall not here offer further explanation. In 

 what are called ** sprains of the fetlock-^*oz?i^," it is not often 

 that there exists any lesion or disease of the joint itself. Mostly, 

 when the swelling is in front, the bursa interposed between the 

 extensor tendon and joint of the fetlock has become dropsical 

 from distention ; and when behind, that large bursa or sheath 

 in which the flexor tendons run, as well as a smaller bursal 

 cavity situate between the tendons themselves, is the seat of eflfu- 

 sion ; accompanying which there is commonly distention of the 

 bursse higher up, the same as constitutes windgall. The sheath 

 in which the flexor tendons run at this part is of a more joint-like 

 construction than sheaths in general ; the concave interspace be- 

 tween the sesamoid bones at the back of the fetlock-joint being 

 lined with a cartilaginous substance, having all the glossy smooth- 

 ness of articular cartilage, and covered the same with synovial 

 membrane. Structure like this renders a sprain of much greater 



* Turn back to page 346. 



