160 THE STRUCTURE OF THE HORSE 



usually happens that one attachment of a muscle is to 

 a point more fixed than the other, and this is then 

 spoken of as its i origin ' ; the attachment to the bone 

 that is most movable being called the £ insertion.' This 

 distinction is, however, not always a satisfactory one, as 

 most muscles may act on occasions either way. In the 

 limbs, where the muscles lie more or less parallel to the 

 long bones, it is convenient to speak of them as arising 

 at the end nearest the body, and being inserted at that 

 farthest from it. As a general rule this accords with 

 their action. 



The muscles are sometimes attached directly to the 

 bone, or rather to the fibrous sheath (periosteum) which 

 closely invests it, but very often, for obvious mechanical 

 reasons, they are connected with the bones by the inter- 

 vention of 'tendons,' strong non-elastic fibrous cords, 

 which are fixed to the muscle at one end and the bone 

 at the other. It is in the limbs especially that tendons 

 play a prominent part, as it is far more convenient that 

 many of the strong muscles that move the fingers and 

 toes should not be placed close to the parts on which 

 they act, as if they were they would give a very clumsy 

 form to the limb. They are, therefore, situated higher 

 up, near the body, where increased thickness and weight 

 of the limb are no disadvantage, and they produce their 

 effect on the toes through the intervention of long 

 tendons, which run close down the side of the bone. 



