42 MUSCLES AND TENDONS 



Union of muscle and tendon. The large majority 

 of muscles have but one tendon, which is at the outer 

 end, or insertion, of the muscle. The inner end, the 

 origin, of the muscle is attached directly to the bone. At 

 the origin, the muscle fibres are attached to the bone 

 by means of a cement so strong that, in spite of the 

 tremendous pulls to which it is subjected, it seldom or 

 never gives way. The other ends of the muscle fibres 

 are cemented to the tendon fibres, which in turn are 

 cemented to the bone. 



Advantages of tendons. An important purpose of 

 the tendon is to economize space, since a slender tendon 

 is strong enough to carry the pull of a powerful muscle 

 over a joint or series of joints, as in the case of the mus- 

 cles of the forearm which move the fingers. If it were 

 not for the tendons, bulky muscles would be required 

 wherever movement was necessary, even in the fingers 

 and toes. Tendons are furthermore so flexible and slip- 

 pery that they readily pass around corners, as in the 

 ankle, without any appreciable loss of power through 

 friction. 



An examination of the arms shows that the muscles 

 which move it lie upon the trunk and are not carried 

 by the arm in its movement. The muscles which move 

 the forearm lie upon the upper arm and as close to the 

 shoulder as possible. In like manner, the muscles which 

 move the wrist, palm and fingers are placed not in the 

 hand but upon the forearm close to the elbow. The 

 long tendons make it possible thus to bring the weight 

 of the muscles upon the more slowly moving parts of 

 the limbs. Upon this distribution of weight, ease and 

 quickness of movement depend. 



Control of joint movements. Wherever in the hu- 

 man skeleton a joint is found, the movement of the 



