280 



THE HIND LEGS. 



Considering the situation and action of this joint, the weight and stress thrown 



upon it must be exceedingly great, 

 CUT OF THE HOCK. and it is necessarily liable to much 



injury in rapid and powerful mo- 

 tion. What are the provisions to 

 prevent injury ? The grooved or 

 pulley-like heads of the tibia and 

 the astragalus, received deeply 

 into one another, and confined by 

 powerful ligaments, admitting 

 freely of hinge-like action ; but 

 of no side motion, to which the 

 joint would otherwise be exposed 

 in rapid movement, or on an un- 

 even surface. A slight inspection 

 of the cut will show that the stress 

 or weight thrown by the tibia a 

 on the astragalus b, does not 

 descend perpendicularly, but in a 

 slanting direction. By this much 

 concussion is avoided, or more 

 readil)^ diflused among the dif- 

 ferent bones; and, the joint con- 

 sisting of six bones, each of them 

 covered with elastic cartilage, and 

 each admitting of a certain degree 

 of motion, the diminished con- 

 cussion is diflused among them 

 all, and thereby neutralised and 

 rendered comparatively harmless. 

 Each of these bones is covered 

 not only by cartilage, but by a 

 membrane secreting synovia ; so 

 that, in fact, these bones are 

 formed into so many distinct 

 joints, separated from each other, 

 and thereby guarded from injury, 

 yet united by various ligaments — 

 possessing altogether sufficient 

 motion, yet bound together so 

 strongly as to def}^ dislocation. 

 When, however, the work which 

 this joint has to perform, and the 

 thoughtlessness and crueltj' with 

 which that work is often exacted, 

 are considered, it will not excite 

 nny surprise if this necessarily complicated mechanism is sometiiues deranged. The 

 hock, from its complicated structure and its work, is the principal seat of lameness 

 behind. 



ENLARGEMENT OF THE HOCK. 



First, there is inflammation, or sprain of the hock-joint gencrnJhj, arising from sud- 

 den violent concussion, by some check at speed, or over-weight, and attended with 

 enlargement of the whole joint, and great tenderness and lameness. This, however, 

 like other diffused inflammations, is not so untractable as an intense one of a more 

 circumscribed nature, and by rest and fomentation, or, perchance, firing, the limb 

 recovers its action, and the horse becomes fit for ordinary work. 



The swellino-. however, does not always subside. Kn'arirement, spread over the 

 whole of tlie bock-joint, remains. Ahorse with an enlarged hock must always be 

 regarded with suspicion. In truth, he is unsound. The parts, altered in structure, 

 must be to a certain degree weakened. The animal may discharge his usual work 



