CHAPTER VI. 

 THE MUSCLES. 



The muscles of the human body are more than five hun- 

 dred in number ; they vary very much in size ; from tiny 

 ones not an inch long, in the voice-box, to that on the front 

 of the thigh (29, PL II.), which passes from the pelvis to 

 the tibia, and is eighteen inches or more in length. What- 

 ever their size, muscles present a similar structure and 

 possess the same properties, their various uses depending 

 on the different directions in which they pull, and the 

 different things they pull upon. In addition to their 

 primary function of moving the body the muscles give it 

 roundness and shapeliness ; they also help to enclose cavi- 

 ties, as the abdomen and the mouth ; and they hold bones 

 together at joints. 



The parts of a muscle. In its commonest form a muscle 

 consists of a red soft central part, called its belly, whioh 

 tapers towards each end and there passes into one or more 

 dense white cords, made of connective tissue and called 

 tendons ; the tendons attach the muscle to parts of tiie 



About how many muscles are there in the body ? Between what 

 limits do they differ in size? In what respects do all muscles resem- 

 ble one another? How are their different uses determined? What 

 functions do muscles fulfill besides moving the body and its parts? 

 Give examples, 



What is the most usual structure of a muscle? What is the use of 

 tendons ? 



[67] 



