1866. | On the Laryngoscope. 221 
When in such a case an ordinary tongue-depressor is employed, it 
sometimes happens that the eatreme base of this organ, which 
cannot be touched by the instrument on account of the retching 
excited, is unavoidably pressed backwards, and the glottis is thus 
closed by its lid, the epiglottis. An instrument which will not only 
depress, but one which will at the same time exert some slight trac- 
tion on the tongue, such as has been already briefly referred to, is 
found very frequently serviceable. 
A knowledge of the structure of the various parts of the larynx 
is, of course, indispensable to those who would study their functions, 
for one can then more readily understand the different appearances 
observable in the laryngeal mirror. 
The condition of the larynx in a quiescent state during ordinary 
tranquil respiration is represented in Fig. 1. The glottis is seen 
to be freely opened, and one observes a large portion of the anterior 
wall of the windpipe. When the person experimented on takes 
a deep inspiration, we see the arytenoid cartilages and vocal cords 
widely separated, the cartilaginous rings of the windpipe, &c.; and, 
if the neck is straightened, we may, in favourable circumstances, 
obtain a view of the bifurcation of this tube,— vide Fig. 2. On 
making a succession of expiratory efforts, as in laughing, in which 
case the syllable “ha” is rapidly repeated, the arytenoid cartilages 
and edges of the vocal cords are suddenly brought into juxtaposition 
and then separated with equal agility during each intermission. 
The action of the larynx during the process of deglutition is 
interesting, but somewhat difficult to observe. It undergoes a 
complete closure, so as to prevent the entrance of any alimentary 
matter.* The changes seen are thus given by Czermak:—1. An 
intimate apposition of the arytenoid cartilages, and of the true and 
false vocal cords occurs. 2. The false vocal cords also approach 
the true cords, so as to obliterate the ventricles of Morgagni. 
3. The epiglottis is lowered, its cushion at the same time becoming 
more and more prominent, until it reaches the fold of mucous 
membrane which encloses the arytenoid cartilages. Figure 3 
represents the commencement of the closure, as seen in the 
laryngeal mirror. When the larynx is completely closed, we see 
an image analogous to that of Figure 4, with this difference, 
however, that in the latter there exists a free space for the passage 
of air between the epiglottis and the arytenoid cartilages, whilst in 
the former this space is occupied by the cushion of the epiglottis, 
and the closure is hermetic. 
The voice is formed, according to Garcia, “by the compressions 
* The conclusions deduced from the experiments of Mons. Guinier, recently 
brought before the Academy of Sciences of Paris, have been questioned. The 
view that the food comes into contact with the vocal cords in deglutition was ably 
refuted by Dr. Gibb at the last annual meeting of the British Association for the 
Advancement of Seience. 
