SENSE ORGANS. 



207 



The Glottis and its Vocal Cords. — The cavity 

 of the larynx is divided into an upper and lower cham- 

 ber by a transverse partition — the glottis. In the glottis 

 there is a fore-and-aft opening — the rima glottidis or chink 

 of the glottis. This chink is 

 bounded on each side by a ^~_-^ — &2L. 



Fig. 133. — View of the larynx from 

 above : ar, the arytenoids ; cr, 

 the cricoid ; c, vocal cords with 

 the rima or opening between. 



Fig. 134. — View from behind : cr, 

 cricoid ; ///, thyroid ; a, aryte- 

 noid ; ep, epiglottis ; hy, hyoid 

 bones. 



firm tendinous cord — the vocal cords. These cords are at- 

 tached in front to the V point of the thyroid, and behind 

 to the two arytenoids (Fig. 133, also Fig. 131). The 

 tension of these cords and the size of the chink or open- 

 ing between them varies very much under different con- 

 ditions. This is determined by observations with the 

 laryngoscope. (1) In quiet breathing the chink is wide 

 open, the cords lax, and the breath comes and goes 

 noiselessly (Fig. 135, A). (2) In aspiration (sighing) 

 the opening remains much the same, but the breath is 

 driven through with a rushing sound. The position of 

 the cords is somewhat as seen in Fig. 133. (3) In 

 making a vocal sound three changes are observed, 

 viz., the vocal cords are brought nearer together, they be- 

 15 



