SIR CHARLES BELL ON THE ORGANS OF THE HUMAN VOICE. 305 
the form and uses of the parts. The thyro-arytenoid ligaments, or chordae vo- 
cales of Ferrein, are the lower ligaments of the glottis ; they form the chink 
of the true glottis. These ligaments do not stand distinct from the sides of 
the tube, but the fine lining membrane is reflected over them. This mem- 
brane, sinking between the inferior and superior ligaments, forms there the 
sacculus or ventriculus laryngis. Another reflexion passes from the extreme 
point of the appendix of the arytenoid cartilage to the base of the epiglottis. 
These inflexions of the membrane of the glottis produce a considerable in- 
tricacy in the passage of the larynx. Nevertheless, when this piece of anatomy 
is fully displayed, the number of muscles inserted into the arytenoid cartilages, 
and the effect of their motions on the lower ligaments, point to these as the 
chief parts, and to the others as subordinate, in producing sound. 
There are, however, circumstances which lead to the belief that the sacculus 
or lateral cavity of the larynx has much influence on sound. We perceive 
that one effect of this cavity is to hold off the inferior ligament from the side 
of the tube, and to give freedom to its vibrations. But the varieties in its size 
and form, exhibited by comparative anatomy, and the influence which some 
of the muscles of the arytenoid cartilages* must have upon it, point it out as 
an essential part of the organ of sound ; and the ear-piercing cries which 
belong to such animals as the Beelzebub ape, in which this cell is large, con- 
firm the notion. 
The seat of the vibrations which produce the voice is so fairly indicated 
by the whole anatomy, and confirmed by observation, that there is hardly an 
excuse for those experiments which have exhibited the motions of the chink of 
the glottis in living animals ■f-. It is, on the whole, better to wait our oppor- 
tunity of inspecting these parts in action in man. In consequence of wounds 
of the throat, I have had repeated occasions to witness the motions of the 
glottis in man, both during simple breathing and in speaking. On every in- 
spiration the glottis is dilated. Upon asking the patient to speak, and encou- 
* Thyro-arytenoideus and Crico-arytenoideus. 
t The larynx of a dog being partially dissected, so as to expose the glottis, the experimenter tor- 
tured the animal to observe how the acuteness of the note, and the constriction of the chink of the 
glottis bore relation to the severity of pain. After ascertaining the degree of contraction from the 
pinch of the tail to the application of the red-hot iron, he set himself with a tuning-pipe to sound in 
harmony. — Archives Generales de Medecine, tom. xxv. Mars 1831. 
