390 DETAILED SYNTHESIS. 



five cartilages, including the epiglottis. The lower, 

 called the cricoid, is shaped in front like a ring of the 

 windpipe, but instead of being open behind it is closed 

 and broad, rising up as shown by 4, Fig. 250. At the 

 FIG 251 upper edge two small triangular carti- 

 lages, called Arytenoid, 5, are jointed in 

 such manner that they can move forward 

 and backward, and toward and from each 

 other. A fourth cartilage, called the 

 thyroid, is large, forming the prominence 

 of the throat, and overrides the cricoid. 

 In Fig. 250 one half is represented as if 

 turned forward, 1 being the inner sur- 

 face, and 3, the point where it is joint- 

 ed to 4 ; 2 is its upper horn ; 6, epiglottis, 

 7, turned up to show 14. 

 Fig. 251. Side view of larynx. 8, trachea; 7, crycoid; 6, thyroid; 

 5, membrane ; 1, 2, 3, 4, hyoid. 



1273. THE MUSCLES OF THE LARYNX are very well 

 shown by 9, 10, 11, 12, 13, 14, 15, Fig. 250, their use be- 

 ing to move the arytenoid and thyroid upon the crycoid, 

 that is, the immovable part of the larynx; 12 is not 

 well represented ; it stretches across more nearly hori- 

 zontal than it appears to, leaving but a small aperture, 

 like a button-hole, between it and its fellow. . 



1274. THE MEMBRANE LINING THE LARYNX is con- 

 tinuous with that of the pharynx and that of the wind- 

 pipe, being somewhat thickened where it covers 12, thus 

 forming the vocal cords, as the edges of the narrow pas- 

 sage are called. (See Pis. 16, 19, 22, and 29, PI. 30.) 



1275. BY THE ACTION OF THE MUSCLES OF THE LAR- 

 YNX the vocal cords can be made more or less tense, and 

 more or less removed from each other at their back part, 

 enlarging or diminishing the size of the slender trian- 

 gular aperture between them. 



1273. What said of f 1274. What said of ? Can a tremulous motion be felt 

 In the larynx when speaking ? 1275. What effected ? 



