THE ORGAN OF VOICE. 201 



Fig. 9, e, Figs. 55, 56, 1 ; it is leaf-like in shape, and acts as a safety- 

 valve, preventing the intrusion of any foreign bodies into the larynx 

 during the act of swallowing. 



Fig. 55. Three views of the dissected human larynx, a, left side of the larynx, showing the cartilages; 

 1, the epiglottis; 2, the thyroid cartilage, its left ala or wing; 4, upper rings of the trachea or windpipe; 

 5, the cricoid cartilage; 6, the left crico-thyroid muscle; *, the position of the left arytenoid cartilage, 

 shown by a faint outline; b, the inner side of the right half of the larynx, which is supposed to have been 

 divided longitudinally down the middle line; 1. section of epiglottis; 2, 2, right half or ala of the thyroid 

 cartilage; 5, ditto of cricoid; 7, right true vocal cord ; above this, is the long opening of the ventricle of 

 the larynx, above that, the false vocal cord ; c, perpendicular section across the larynx, showing the pos- 

 terior surface of the anterior half of the organ; 1, hinder surface of the epiglottis; 2, section of the right 

 half of the thyroid cartilage ; 3, section across both the vocal cords, and the intermediate chink, or glottis, 

 with the ventricles of the larynx above them; 4, anterior part of the trachea. 



The inferior or tracheal opening of the larynx is small, and round- 

 ish : but the superior or pharyngeal opening, Fig. 56, is larger, and 

 triangular in form, being wide in front and narrow behind. It is 

 bounded on the sides by two folds of mucous membrane, which pass 

 from the arytenoid cartilages * forwards, to the side of the epiglottis, 

 1, which may be said to form its anterior boundary. On looking 

 down through this opening, two folds of the lining membrane are seen 

 passing from the arytenoid cartilages behind, to the receding angle of 

 the thyroid cartilage in front : these are the superior or false vocal 

 cords, so named because they are not concerned in the production of 

 the voice. Below these, and extending from the small process or pro- 

 jection on the fore part of the arytenoid cartilage, to the recessed part 

 of the thyroid cartilage, are the true vocal cords, Figs. 55, 56, 7, the 

 essential organs of voice ; they are made up chiefly of yellow elastic 

 tissue, covered by mucous membrane ; and they form two sharp ridges 

 or projections, having very fine and smooth edges, turned towards 

 each other, and placed accurately on the same level. Between the 

 true vocal cords, Fig. 56, is a harrow, somewhat triangular interval 

 or fissure, wider behind than in front, called the glottis, or rima glot- 

 tidis or chink of the glottis ; in man, it is about eleven lines in length, 

 and nearly half an inch in width at its widest part ; its measurements 

 in the female, are two or three lines less ; at its hinder part, or base, 

 the triangular fissure is bounded by the arytenoid cartilages, on either 

 side, for the vocal cords do not extend so far back. This hinder part 

 of the fissure is called the arytenoid portion. Above each true vocal 

 cord is a cavity on either side, named the ventricle of the larynx, ? Fig. 



