CHAPTER VII. 

 MOTION AND LOCOMOTION. 



The special physiology of muscles. The distinctive prop- 

 erties of muscle are everywhere the same ; it has the power 

 of contracting ; but the uses of different muscles are very 

 varied by reason of the different parts to which they are 

 attached. Some are muscles of respiration, others of 

 siv allowing ; some bend joints and are called flexors, others 

 straighten them and are called extensors, and so on. 

 The determination of the exact use of any particular 

 muscle is known as its special physiology, as distinguished 

 from its general physiology, or properties as a muscle, 

 without reference to its use as a muscle in a particular 

 place. We may here consider the special physiology of the 

 muscles concerned in standing and walking. 



Levers in the body. In nearly all cases the voluntary 

 muscles carry out their special functions with the co-oper- 

 ation of the skeleton ; most of them are joined to bones 

 at each end and when they contract move the bones, 



In what respect are all muscles alike? Have all muscles the same 

 uses? Give instances of the employment of muscles for different pur- 

 poses. What is meant by the special physiology of a muscle? What 

 by its general physiology? 



With what do the voluntary muscles co-operate? To what are the 

 ends of nearly all muscles attached? What happens when a muscle 

 contracts? 



[80] 



