While the _false vocal bands_ have little or nothing to do with phonation directly, they do serve a good purpose as protectors to the more exalted true vocal bands. When coughing, swallowing, vomiting, holding the breath tightly, etc., these folds of mucous membrane close over the true bands, often completely, and thus shut up for the moment the whole of that space between the bands known as the glottis, or glottic chink, to which reference was made in a previous chapter as the space through which the air finally gains access to the lungs. The true vocal cords (which, because of having some breadth and being rather flat, are better termed vocal bands) are composed largely of _elastic tissue_. The reader may be familiar with this structure, which is often to be found in the portions of the neck of the ox that the butcher sells as soup beef. It is yellow in color, and stretching it has furnished many a boy with amusement. It is so unmanageable when raw that when it falls to the dog he usually bolts it, the case being otherwise hopeless. Such elastic tissue is, however, the very material for the construction of vocal bands, as they require to be firm yet elastic. [Illustration: FIG. 25 (Spalteholz). A view of the larynx from behind. Several of the muscles are well shown, of which the two indicated above are of the most importance. The arytenoideus proprius tends to bring the cartilages from which it is named, and therefore the vocal bands, toward each other; while the posterior crico-thyroid, from its attachments and line of pull, tends to separate these and lengthen the vocal bands.] [Illustration: FIG. 26 (Spalteholz). Showing structures as indicated above. The mucous membrane, that naturally covers all parts within the vocal mechanism, has been dissected away to show the muscles.] [Illustration: FIG. 27 (Spalteholz). Showing the parts indicated above; and of these the crico-thyroid muscle is to be especially observed. The oblique (especially so in the posterior part) direction of its fibres is evident, so that when it contracts, it must pull up the ring cartilage in front, and so tilt back its hinder portion and with it the arytenoid cartilages, and so lengthen and tense the vocal bands, as in the utterance of low tones.] [Illustration: FIG. 28 (Spalteholz). A back (posterior) view of the larynx, etc. Note how the arytenoid cartilages rest on the cricoid; how the epiglottis overhangs, as its name implies, the glottis; and that the posterior part of the windpipe is closed in by soft structures, including (unstriped) muscle.] It is important to remember the relative position of parts and to bear in mind that most of the laryngeal structures are in pairs. To this last statement the thyroid and cricoid cartilages and the epiglottis are exceptions, being single.