THE LIMBS. 171 



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 intervention 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 mus- 

 cles 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. 



As all the joints of the limbs of the horse are sim- 

 ply hinge-joints, acting only in one plane, the muscles 



