CH. LV.] MOVEMENTS OF THE VOCAL CORDS 757 



line the true vocal cords, white and shining in their normal condition. The cords 

 approximate (in the inverted image) posteriorly; between them is left a chink, 

 narrow whilst a high note is being sung, wide during a deep inspiration. On each 

 side of the true vocal cords, and on a higher level, are the pink false vocal cords. 

 Still more externally than the false vocal cords is the aryteno-epiglottidean fold, in 

 which are situated upon each side three small elevations ; of these the most external 

 is the cartilage of Wrisberg, the intermediate is the cartilage of Santorini, whilst 

 the summit of the arytenoid cartilage is in front, and somewhat below the preceding, 

 being only seen during deep inspiration. The rings of the trachea, and even the 

 bifurcation of the trachea itself, if the patient be directed to draw a deep breath, 

 may be seen in the interval between the true vocal cords. 



Movements of the Vocal Cords. 



In Respiration. The position of the vocal cords in ordinary 

 tranquil breathing is so adapted by the muscles, that the opening 

 of the glottis is wide and triangular (fig. 558, B). For all practical 

 purposes, the glottis remains unaltered during ordinary quiet breath- 

 ing, though in a small proportion of people it becomes a little wider 

 at each inspiration, and a little narrower at each expiration. In the 

 cadaveric position the glottis has about half the width it has during 

 ordinary breathing ; during life, therefore, except during vocalisation, 

 the abductors of the vocal cords (posterior crico-arytenoids) are in 

 constant action. (F. Semon.) On making a rapid and deep inspira- 

 tion the opening of the glottis is widely dilated (fig. 558, c), and 

 somewhat lozenge-shaped. 



In Vocalisation. At the moment of the emission of a note, the 

 chink is narrowed, the margins of the arytenoid cartilages being 

 brought into contact, and the edges of the vocal cords approximated 

 and made parallel (fig. 558, A); at the same time their tension is 

 much increased. The higher the note produced, the tenser do the 

 cords become; and the range of a voice depends, in the main, on 

 the extent to which the degree of tension of the vocal cords can 

 be thus altered. In the production of a high note the vocal 

 cords are brought well within sight, so as to be plainly visible 

 with the help of the laryngoscope. In the utterance of low-pitched 

 tones, on the other hand, the epiglottis is depressed and brought 

 over them, and the arytenoid cartilages look as if they were trying 

 to hide themselves under it (fig. 559). The epiglottis, by being 

 somewhat pressed down so as to cover the superior cavity of the 

 larynx, serves to render the notes deeper in tone and at the same 

 time somewhat duller. 



The degree of approximation of the vocal cords also usually 

 corresponds with the height of the note produced ; but the width of 

 the aperture has no essential influence on the pitch of the note, as 

 long as the vocal cords have the same tension : only with a wide 

 aperture the tone is more difficult to produce and is less perfect, the 



