960 THE ORGANS OF VOICE AND RESPIRATION. 



vocal cords in front, and between the bases and vocal processes of the arytenoid 

 cartilages behind. It is therefore frequently subdivided into an anterior interliga- 

 mentous or vocal portion (glottis vocalis) and a posterior intercartilaginous or 

 respiratory part (glottis respiratoria). Posteriorly it is limited by the mucous 

 membrane passing between the arytenoid cartilages. The vocal portion averages 

 about three-fifths of the length of the entire aperture. It is the narrowest part of 



Corniculum laryngis. 



Inferior vocal ' "^L jflkk f 



> -, f^ Apex of sup. horn of 



^ -thyroid <;,,-fil<,<: 



Cuneiform eartilaye. 



Aryteno-epiglottic 



fold. 



Apex of great 

 horn of hyoid. 



Lateral glosso- 

 epiglottic fold. 



To Tig in 



Middle glosso-epiglottic fold. 



FIG. 529. Larynx, viewed from above. (Testut.) 

 * 



the cavity of the larynx, and its level corresponds to the bases of the arytenoid 

 cartilages. Its length, in the male, measures rather less than an inch ("20-25 mm.) ; 

 in the female it is shorter by 5 or 6 mm., or three lines. The width and shape 

 of the rima glottidis vary with the movements of the vocal cords and arytenoid 

 cartilages during respiration and phonation. In the condition of rest i. e., when 

 these structures are uninfluenced by muscular action, as in quiet respiration the 

 glottis vocalis is triangular, with its apex in front and its base behind, the latter 

 being represented by a line about 8 mm. long, connecting the anterior extremities 

 of the vocal processes, while the inner surfaces of the arytenoids are parallel to 

 each other, and hence the glottis respiratoria is rectangular. During extreme 

 adduction of the cords, as in the emission of a high note, the glottis vocalis is 

 reduced to a linear slit by the apposition of the cords, while the glottis respiratoria 

 is triangular, its apex corresponding to the anterior extremities of the vocal 

 processes of the arytenoids, which are approximated by the inward rotation of the 

 cartilages. Conversely in extreme abduction of the cords, as in forced inspiration, 

 the arytenoids and their vocal processes are rotated outward, and the glottis respi- 

 ratoria is triangular in shape, but with its apex directed backward. In this con- 

 dition the entire glottis is somewhat lozenge-shaped, the sides of the glottis vocalis 

 diverging from before backward, those of the glottis respiratoria diverging from 

 behind forward, the widest part of the aperture corresponding with the attachment 

 of the cords to the vocal processes. 1 



The superior or false vocal cords, so called because they are not directly con- 

 cerned in the production of the voice, are two thick folds of mucous membrane, 

 enclosing a narrow band of fibrous tissue, the superior thyro-arytenoid ligament, 

 which is attached in front to the angle of the thyroid cartilage immediately below 

 the attachment of the epiglottis, and behind to the anterior surface of the aryte- 

 noid cartilage. The lower border of this ligament, enclosed in mucous membrane, 

 forms a free crescentic margin, which constitutes the upper boundary of the ven- 

 tricle of the larynx. 



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. 



