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INTERIOR OF THE LARYNX. IL? 
points of the vocal processes of the arytenoid cartilages, whilst the glottis respira- 
toria is somewhat quadrangular. When the glottis is opened widely the broadest 
part of the fissure is at the extremities of the vocal processes of the arytenoids, 
and here the side of the rima presents a marked angle. The two vocal cords, on 
the other hand, may be approximated to each other so closely, as in singing a high 
note, that the glottis vocalis is reduced to a linear chink. 
The length of the rima glottidis differs very considerably in the two sexes, and upon this 
depends the different character of the voice in the male and female. According to Moura, the 
following are the average measurements in the quiescent condition of the rima :— 
Male—Length of entire rima glottidis, f glottis vocalis, 15°5 mm. 
23 mm. : 3 : : . (glottis respiratoria, 75 mm. 
Female—Length of entire rima glottidis, f glottis vocalis, 11°5 mm. 
17 mm. : : : i . | glottis respiratoria, 5°5 mm. 
By stretching the vocal cords, however, the length of the rima glottidis in the male may 
be increased to 27°5 mm., and in the female to 20 mm. 
The position of the rima glottidis may be indicated on the surface by marking a point on the 
middle line of the neck 8°5 mm. below the bottom of the thyroid notch in the male and 65 im. 
in the female. This is the average position (Taguchi). 
Laryngeal Sinus (ventriculus laryngis)—The side wall of the larynx, in the 
interval between the false and the true vocal cords, exhibits a marked pocket-lke 
depression or recess called the laryngeal sinus. The recess passes upwards so as 
to undermine somewhat the false vocal cord, and its mouth is somewhat narrower 
than its cavity. In front it reaches forwards to the angle between the alee of the 
thyroid cartilage, whilst behind it ends at the anterior border of the arytenoid 
cartilage. 
Under cover of the forepart of the false vocal cord a small sht-like aperture 
may be detected; this leads upwards from the laryngeal sinus into a small diverti- 
culum of mucous membrane, termed the laryngeal saccule (appendix ventriculi), 
which ascends between the false vocal cord and the ala of the thyroid cartilage. 
The laryngeal saccule is of variable extent, but as 
a rule it ends blindly at the level of the upper 
border of the thyroid cartilage. 
Saecule 
Sometimes the saccule extends much higher, and may 
even reach the hinder part of the great cornu of the 
hyoid bone. ‘This is of interest when considered in 
connexion with the extensive laryngeal pouches of the 
anthropoid apes. 
Lower Compartment of the Laryngeal Cavity. 
—This leads directly downwards into the trachea. 
Above it is narrow and compressed laterally, but 
it gradually widens out until,in its lowest part, it 
becomes circular, in correspondence with the trachea 
with which it is continuous. It is bounded by the Fic. 620.—Sprcimey sHowrne A GREAT 
sloping inner surfaces of the crico-thyroid membrane oe OR THE SAOCULE Ona 
and by the inner aspect of the cricoid cartilage ze 
both covered by smooth mucous membrane. In the operation of laryngotomy the 
opening is made through the anterior wall of this compartment. 
Mucous Membrane of the Larynx.—The mucous membrane which lines the 
larynx is continuous above with that lining the pharynx, and below with mucous 
membrane of the trachea. Over the posterior surface of the epiglottis it is closely 
adherent, but elsewhere, above the level of the true vocal cords, it is loosely 
attached by submucous tissue which extends into the aryteno-epiglottidean folds. 
As it passes over the true vocal cords the mucous membrane is very thin, and is 
tightly bound down. 
It is important to bear these facts in mind, because in certain inflammatory conditions the lax 
submucous tissue in the upper part of the larynx is liable to become infiltrated with fluid, pro- 
ducing what is known as edema glottidis. This may proceed so far as to cause occlusion of the 
upper part of the cavity. The close adhesion of the mucous membrane to the true vocal cords, 
