THE HIND EXTREMITIES. 97 



of the large muscles of the back of the thigh being 

 inserted into the back and upper third of the tibia 

 surrounding the 'calf to some extent. The muscles 

 on the outer side of the tibia (Fig. 14, 7) called the 

 gaskin muscles well seen in Fig. 1 5 are extremely pro- 

 minent, and measureable with the eye, and as we have 

 seen, extend the toe and foot. Little notice then need 

 be taken of the long arm of the lever under considera- 

 tion. With a long lever arm, and the same bulk 

 and strength of 'calf required for a short lever arm 

 attached to it the hock would be torn asunder. 

 This, as we have seen, cannot be the case. The 

 weight surface of the lever is applied against 

 the astragalus. The fulcrum concerns us most, as 

 it is fixed by means of ligaments which are some 

 times torn or otherwise injured, and which swell 

 and inflame in consequence, and the horse is 

 then said to have ' sprung a curb.' The place of 

 this occurrence is marked at Fig. 14, (3. 



The ' irregular ' bones or buffers are placed at 

 the lower part of the hock, and are two tiers having 

 joints between them. They are very much jarred 

 when the hock is flexed smartly as in that quick 

 fascinating hock action we sometimes witness, and 

 then the inner ones undergo change and tlirow out a 

 soft plastic material which in time hardens into bone, 

 and is called ' bone spavin ' or a ' jack.' Much de- 

 pends on the size of these buffer bones .If they are 

 large they serve their purpose, and we may have a 

 good hock. They form the whole of the lower part 



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