42 THE CANADIAN HOESB 



the back tendons. As these tendons (flexor perforans and 

 f. perforatus) are the chief agents in producing the motions 

 of the limbs, acting like levers over the pulley-like surfaces 

 on the ends of the bones in their passage down to the foot, 

 they are consequently very liable to be overstretched and 

 strained, sometimes in a very slight degree, and sometimes 

 to a considerable extent. It may be necessary here to notice 

 the arrangement of these two tendons. The muscles (per- 

 forans and perforatus) arise from below the elbow-joint, pass 

 down through a theca at the back of the knee ; below the 

 knee they become tendinous ; the first is round, and is 

 covered by the other, which is flatter ; half-way down the 

 cannon, the perforans is joined by a strong ligament, (the 

 metacarpal) ; the two tendons pass down together through a 

 sheath formed for them at the back of the fetlock ; the latter 

 splits into two divisions, having the perforans passing be- 

 tween them ; they are inserted one into each side of the lower 

 pastern-bone, (os coronse,) the perforans, passing down, is 

 inserted into the sole of the coffin-bone, just in front of the 

 navicular joint, over which it passes. In most of the> so- 

 called cases of clap or sprain of the back-tendons, the liga- 

 ment, and not the tendon, is the seat of the injury. 



Causes. — ^Whatever tends to throw unusual stress upon, 

 these parts may produce it, such as galloping on uneven 

 ground, allowing the hoofs to grow too long, thereby in- 

 creasing the leverage on the tendon ; sometimes it occurs in 

 leaping, often while jumping around in play. 



Symptoms. — The animal is very lame, the part is hot, 

 swollen, and tender ; the limb is held forward, so as to relax 

 the part ; in some cases, he can hardly touch the ground. 

 On taking up the foot and pinching with the fingers, he 

 evinces the pain he feels. If the outer tendon (perforatus) 

 is injured, we have a bulging out behind, interrupting the 



