CON TIL l BUT IONS TO ZOOLOGICAL PATHOLOGY. 
353 
lage by the thyroideal slips of the sterno-hyo-thyroidei muscles, 
we must come to the conclusion that the intrinsic movements of 
the skeleton of the larynx are very nicely and accurately balanced, 
and that there is no preponderance of power in favour of either of 
the above group of muscles*. 
The Epiglottic Gland. 
This is' the name given to a dense mass of ligamentous, adipose, 
and cellular substance, situated between the convex surface of the 
epiglottis, and resting on the thyro-h}mid membrane and the angle 
of the thyroid cartilage. Though usually described as being 
glandular in structure, with its ducts passing through the substance 
of the epiglottis, and opening upon its laryngeal surface, yet this 
can be with difficulty detected or established. It would rather 
appear to be only a means of connexion between the epiglottis and 
thyroid cartilage — the thyro-epiglottidean ligament. 
The Laryngeal Mucous Membrane. 
The mucous membrane of the larynx is continuous with that 
which lines the mouth and pharynx. On tracing it backwards from 
the base of the tongue, it passes directly upon the epiglottis, and 
forms between them three folds, the central or frcenum epiglottidis, 
and the two lateral glos so- epiglottic folds. These folds simply 
consist of duplicates of the mucous membrane, containing a quantity 
of loose cellular tissue, in which are imbedded numerous small 
mucous follicles: passing upwards and backwards, from the sides 
of the epiglottis to the apices of the arytenoid cartilages, it is 
formed into other two folds, the aryteno-epiglotlic folds , consti- 
tuting, between them, the anterior aperture of the larynx. The 
external surface of these folds becomes continuous with the 
mucous membrane of the side of the pharynx, and, posteriorly 
passing over the arytenoid and cricoid cartilages, it descends back- 
wards into the oesophagus. The internal surface of these folds 
passes backwards into the larynx, and, being folded over the ap- 
pendages of the epiglottis, forms the anterior or false vocal chords ; 
and having formed these, it swells out on either side, between 
the anterior and posterior thyro-arytenoid muscles, to form the 
ventricles of the larynx ; and, again, being reflected over the true 
* For a fuller account of the mechanical and physical changes induced in 
the essential structures of the larynx of man, during its movements, the stu- 
dent is referred to the Memoirs of Willis, Camb, Philos. Trans., vol. 4, 1832 ; 
Lauth, Mem, de l’Academie Royale de Med., 1835 ; Bishop, Cycloped. of 
Anat., vol. 3, article “larynx.” 
