354 CONTRIBUTIONS TO ZOOLOGICAL PATHOLOGY. 
vocal chords, it passes backwards, to become the tracheal mucous 
membrane. The entire laryngeal membrane is perforated by ori- 
fices of numerous mucous follicles, and its sensibility is particularly 
great in the ventricles and about the vocal chords. 
The Ventricles of the Larynx. 
The ventricles of the larynx are the two oval or elliptical 
cavities, situated between the anterior and posterior vocal chords. 
Anteriorly they are bounded by the false, and posteriorly by the 
true vocal chords. Internally they open into the cavity of the 
larynx, and externally they are imbedded in the loose cellular 
tissue, between the superior and inferior thyro-arytenoid muscles. 
At the posterior part of either cavity a small sinus is sometimes 
found, leading backwards and upwards into a small pouch or diver- 
ticulum, the sacculus laryngis. This T have found repeatedly in 
man, often in the dog and cat, but seldom in the horse. When 
it does exist, it is merely a supplementary cavity to its correspond- 
ing ventricle. The ventricles being lined by mucous membrane 
contain a considerable number of mucous follicles, the fluid from 
which, when collected in the cavities, becomes discharged into the 
larynx by the contraction of the aryteno-epiglottidei muscles, 
which are expanded upon their anterior and external walls. 
The Rima Glottidis. 
It has already been mentioned that the rima glottidis is formed 
between the opposed edges of the posterior thyroid-arytenoid folds, 
or true vocal chords. It is the narrowest space in the larynx, and 
forms the point of entrance between the cavity of the larynx and 
the trachea. It is of a triangular form, the base being placed supe- 
riorly and posteriorly, and is formed by the arytenoid cartilages, 
and the apex inferiorly, in the angle of the thyroid cartilage. The 
structures which form it being attached to the bases of the arytenoid 
cartilages, whatever change of position takes place in them will 
also produce a change in the size and form of the rima glottidis. 
These have been already treated of, when speaking of the actions 
of the muscles of the larynx. 
[To be continued.] 
