Diseases of the Air Passages of the Larynx. 11.

Otago Witness, Issue 2667, 26 April 1905, Page 65

Diseases of the Air Passages of the Larynx. 11.

We have described the general construction and mechanism of the larynx, and it i 3 necessary to enter into a few details in order to complete our view of its anatomy. Below the stretched cords (vocal cords) is the tube along which air passes into the lungs, and called the windpipe or trachea, into the constriction of which wo shall enter later. The* cords themselves are formed, as we saw, by the free edges of a membrane, and ihey arc tough, and in health have a pearly-white colour. When they are tight they lie nearly parallel to each othor, and with only a small gap between, through which the air pa?isci3 to- produce a note. The pitch of note is determined by the degree of tightness and the length of their free border. In normal breathing the cords do not He parallel, but are further apart towards the back, producing a four-sided opening with two long sides towards the front and two short sides at tho back.

Just outside and above the vocal cords is a space enclosed by two folds of membrane, r.ot unlike the true vecal cords in shape, but without their pearly colour and without their function, and capable of producing obstruction, as we shall see, when swollen. These folds are called the "false cords."

The only other part which demands description is the "epiglottis" — so called from "epi," meaning "upon," and "glottis," the chink of the larynx between the cords. This ia a piece cf cartilage of oblong shape, and attached to the. base of the tongue above the larynx. The older view was that it covers over the glottis when we swallow and throws food backwards, so that it fails to get into the larynx as it passes downwards into the gullet on its way to the stomach. If you will attend to your throat as you swallow you will find that the tongue passe-s backwards. This causes the base of the tongue with the epiglottis attached to fall downwards, m.ote or less covering the larynx; but this is not ajl, for you will see that the larynx is pulled upwards and forwards, placing it further under their shelter. "Were it not for these movements, the ordinary act of swallowing, which w© are continually executing 1 , would bo invariably accompanied by the violent coughing -which the entrance of even a drop of pure- water into the sensitive larynx causes spasmodically. And even with these elaborate precautions it doea happen occasionally. Wo saw that small cartilages (arytenoids) were attached to tihe upper part of the lower cartilage (cricoid), and the mucous membrane which reaches from the larynx to tho epiglottis above is thrown into folds, some of the more pronouncod of which are railed the arytcno-epigloHidcan folds, beneath which there arc fchiu bands of muscle,

influencing 1 the relative position of the cartilages and the epiglottis together with these folds themselves. — Liverpool Mercury.