1104 



THE ORGANS OF VOICE AND RESPIRATION. 



arytenoid ligament are covered by mucous membrane prolonged from that of the 

 true cords, and are the lateral boundaries of this portion of the cavity of the larynx. 

 The Crico-thyroid Ligaments. These are capsular ligaments which enclose on 

 each side the articulation of the inferior cornu of the thyroid with the cricoid 

 cartilage. The articulation is lined by synovial membrane, and strengthened by 

 accessory (kerato-cricoid) ligaments which pass from the tip of the cornu in various 

 directions to the cricoid. 



The crico-arytenoid ligaments are two capsular and two posterior. The cap- 

 sular are thin and loose capsules attached to the margins of the articular surfaces ; 

 they are lined internally by synovial membrane. The posterior extend from the 

 cricoid to the inner and back part of the base of the arytenoid cartilage. 



The crico-tracheal ligament connects the cricoid cartilage with the first ring of 

 the trachea. It resembles the fibrous membrane, which connects the rings of the 

 trachea to each other. 



INTERIOR OF THE LARYNX. The superior aperture of the larynx (Fig. 701) is 

 a cordiform opening, wide in front, narrow behind, and sloping obliquely downward 

 and backward. It is bounded in front by the epiglottis, behind by the inter-ary- 

 tenoid fold of mucous membrane passing between the arytenoid cartilages, and lat- 

 erally, by a fold of mucous membrane enclosing areolar tissue and muscular fibres, 

 stretched between the sides of the epiglottis and the apex of the arytenoid carti- 

 lages : these are the aryteno-epiglottic folds, on the margins of which the cuneiform 

 cartilages and cornicula form more or less distinct whitish prominences. 



The cavity of the larynx extends from the superior aperture to the lower 

 border of the cricoid cartilage. It is divided into two parts by the projection 

 inward of the true vocal cords ; between the two cords is a long and narrow trian- 

 gular fissure or chink, the glottis, of which the boundary is the rima glottidis. The 

 portion of the cavity of the larynx above the true vocal cords is broad, and contains 

 the false vocal cords, between each of which and the corresponding true vocal cord 

 is the corresponding ventricle of the larynx. The portion below the true vocal 

 cords is at first elliptical, and lower down circular, in form. 



The glottis is the narrow fissure or chink between the inferior or true vocal 

 cords in front (inter-ligamentous portion), and the vocal processes of the arytenoid 



cartilages behind (intercartilag- 

 inous portion). It is the nar- 

 rowest part of the cavity of the 

 larynx. Its length in the male 

 measures rather less than an 

 inch, its breadth when dilated 

 varying at its widest part from 

 a third to half an inch. The 

 form of the glottis varies. In 

 its half-closed condition it is a 

 narrow fissure, a little enlarged 

 and rounded behind. In quiet 

 breathing it is somewhat trian- 

 gular, the base of the triangle 

 directed backward, and corre- 

 sponding to the space between 

 the arytenoid cartilages. When 

 widely open it is lozenge -shaped. 

 In forcible expiration it is 

 smaller than during inspiration. 

 When sound is produced it is 



more narrowed, the edges of the vocal cords being approximated and made parallel, 

 the approximation and tension corresponding to the height of the note produced. 1 



1 On the shape of the rima glottidis in the various conditions of breathing and speaking, see 

 Czermak, On the Laryngoscope, translated for the New Sydenham Society. 



V 



FIG. 701. The larynx and adjacent parts, seen from above. 



