2 7 6 



OUR BODIES AND HOW WE LIVE 



Two slender, ladle-shaped cartilages are placed on the 

 top of the back part of the cricoid. They work with a 

 ball-and-socket joint and have tiny muscles which regulate 

 ^r-r->^ their movements with the utmost 



accuracy. 



380. The Vocal Cords. From 

 each of the two ladle-shaped carti- 

 lages a band of elastic tissue passes 

 forward and is joined to the inner 

 and front part of the shieldlike 

 cartilage towards its lower edge. 

 These two bands, called the vocal 

 cords, are narrow strips of firm, 

 fibrous material with a chinklike 

 opening between them called the 

 glottis, meaning the mouthpiece of 

 a flute. These cords are the real 

 organ of voice. 



All the air which goes out of or 

 into the lungs must go through the 

 glottis. There are muscles and 

 cartilages which serve to tighten 

 or loosen these cords. During 

 ordinary breathing the vocal cords are widely separated. 

 381. How the Voice is produced. If the air is driven out 

 of the lungs by an act of expiration when the cords are 

 in a state of tension, they vibrate and produce the sound 

 called the voice. 



The different musical sounds produced in singing depend 

 upon the length and the varying degree of tension of the 

 vocal cords. The compass of the voice depends upon the 

 extent to which the variations can take place. A practiced 



FIG. 174. Cartilages and 

 Ligaments of the Larynx. 

 (Posterior view.) 



A, epiglottis ; B, thyroid carti- 

 lage ; C, ladle-shaped carti- 

 lage; JS, cricoid cartilage; 

 F, upper ring of the wind- 

 pipe. 





