MECHANISM: OF THE VOICE. 



157 



the true and false ligaments of the glottis or vocal cords, on 

 either side there is a cavity, called the ventricle of the larynx. 

 Lastly, superiorly, the upper aperture of the larynx (which 

 must not be confounded with the rima glottidis) is protected 

 by a fibre-cartilage, of a triangular shape, called epiglottis, 

 by means of which, during deglutition, the larynx is still 



further protected from the accidental passage of food or drink 

 into the air-tubes, the effect of which accident, unless in- 

 stantly relieved, is suffocation. 



299. Mechanism of the Voice. In the ordinary state 

 the air passes and repasses the larynx, and no sound is heard ; 

 but when the muscles of the larynx contract so as to modify 

 the vocal cords as to tension, and to affect the diameter of the 

 rima glottidis, sounds are immediately produced. The cele- 

 brated Galen divided in a living animal the nerves proceeding 

 to the larynx, and first showed the phenomenon to depend on 

 muscular action influenced by the nerves. By cutting the 

 true vocal cords the voice is destroyed altogether. 



* Fig. 111. The male larynx viewed in profile : h, hyoid bone ; I, body of 

 the hyoid, giving attachment to the base of the tongue ; t, thyroid cartilage ; 

 a, salient angle of the thyroid cartilage, which may be felt on the surface of 

 the neck (pomum Adami) ; a membraniform ligament unites the thyroid 

 cartilage to the hyoid bones ; c, cricoid cartilage ; tr, trachea or windpipe ; 

 o, posterior wail of the larynx in relation with the gullet. 



Fig. 112. Vertical section of the larynx; k, hyoid bones ; t, thyroid car- 

 tilage ; c, cricoid cartilage ; ar, arytsenoid cartilages ; v, ventricle of the 

 glottis and of the larynx, formed as described in the text ; e, epiglottis ; tr, 

 trachea. 



Fig. 113. Larynx, front view ; the contour of the inner wall is indicated by 

 the dotted lines aa, bb : li, true vocal cords, or inferior ; Is, false ditto, or 

 superior. The other parts are indicated by the same letters as in the pre- 

 ceding figures. 



