Part 10

From the anterior surface of the _arytenoid cartilages_, extending towards the centre of the inner wall of the _thyroid cartilage_, running diagonally through the cavity of the larynx, are stretched the two pairs of chords already more than once mentioned--the vocal chords, consisting of folds of the mucous membrane which envelopes the whole larynx. The two lower of these chords, the vocal chords strictly so called, into which the _cuneiform cartilages_ project and through which the interior thyro-arytenoid muscles run, have their points of attachment at the _arytenoid cartilages_, somewhat lower than the upper pair. Each of these parallel pairs of chords form between their lips a slit running antero-posteriorly. The slit of the upper pair is opened in the shape of an ellipse; that of the lower pair, the glottis, is very narrow. As the upper chords have their point of attachment posteriorly and higher, they form with the lower chords two lateral cavities, the ventricles.

The two pairs of chords, therefore, are the free interior edges of the membrane, covering the whole larynx and extending into it to the right and the left. Only the lower vocal chords serve directly for the generation of tones. More or less stretched and presenting resistance to the air forcibly expired from the lungs through the trachea, they are thus made to vibrate. The upper or false vocal chords do not co-operate with them to generate tone, but like all the remaining parts of the mouth and throat belong to the resonance apparatus of the voice, to which also appertains the back part of the mouth, the _pharynx_, over the œsophagus, the throat, or gullet. This is separated from the anterior cavity of the mouth by the palate, which is a curtain formed by the mucous membranes of the cavity of the mouth, and the centre of which forms the pendent uvula.

Above the œsophagus, immediately over the palate, lie close together, and separated only by a very thin osseous partition, the two posterior nasal orifices. These serve as passages for the air during inspiration and expiration; they are likewise considered as belonging to the resonance apparatus.

Upon both sides of the cavity of the mouth, between the two wings of the palate, lie the tonsils, two glandular bodies, which separate the sides of the cavity of the mouth from the _pharynx_. The anterior cavity of the mouth, which is separated from the nasal cavities by the palate, requires no description, as every one can acquaint himself with its structure in his own person and in others. Upon its formation, as well as upon the position of its different parts and upon the character of those parts of the larynx and of the cavity of the mouth which have been described as the resonance apparatus, the difference in the fulness and timbre of tones depends.

The _epiglottis_ is fixed at the anterior portion of the larynx, at the root of the tongue, within the angle formed by the two surfaces of the thyroid cartilage. It is a very elastic fibro-cartilage, freely moving in a posterior direction. Its color is yellowish and its general form that of a spoon; its upper surface is covered with a multitude of little mucous glands set in shallow cavities. In the downward passage of food the _epiglottis_ covers the upper orifice of the larynx like a valve, over which the food passes into the œsophagus or gullet, without being able to enter the larynx and the trachea. In the centre of its interior side there is a little rounded cartilage, movable in every direction, which has as yet no name. Czermak mentions it first in his observations with the laryngoscope. In the male larynx, after the voice has altered, the cartilages become more or less ossified and gradually harden with increasing age. The cartilages of the female larynx, with rare exceptions, usually continue with little or no change. The muscles, by which the movements of the larynx are effected, are:

I. The posterior crico-arytenoid. II. The lateral crico-arytenoid. III. The crico-arytenoid. IV. The thyro-arytenoid. V. The arytenoid. VI. The internal thyro-arytenoid.

In late works upon laryngoscopy the different muscles of the larynx are variously designated and divided. Bataille terms the first three of the above-named muscles the exterior muscles of the larynx; the three others he comprehends under the name of thyro-arytenoid or vocal muscle, which divides into three slips in the interior of the larynx. This, however, as well as the description of the character and action of the different muscles, belongs to the department of science. What I have already stated seems to me to be sufficient for an understanding of the action of these organs in the production of sound in the different registers. The reader is referred to any good manual of anatomy for a full description of the muscles, ligaments, nerves, vessels and membranes.

THE END.

TRANSCRIBER'S NOTE.

The following amendments have been made to the original text:

Page 24: “and were the forerunners of the opera and oratorio” for “and were the fore-/runners of the opera and oratorio”

Page 26: “But in that brilliant springtime of vocal art” for “But in that brilliant spring-/time of vocal art”

Page 30: “i.e., the old singing masters taught” No comma in original (added for consistency).

Page 42: “by their anterior apophyses, without leaving any space” Comma missing from original.

Page 48: “vol. x. 4th Series, pp. 218-221, 1855.” for “vol. x. 4th Series, p. 218-221, 1855.”

Page 66: “i.e., those tones where a different action” No comma in original (added for consistency).

Page 79: “the tones of the head register.” Period missing from original.

Page 87: “the reed of the mouthpiece.” for “the reed of the mouth-/piece.”

Page 108: “the air coming from the lungs through the trachea,” for “the air coming from the lungs through the treachea,”

Page 118: “then the high inharmonic over-tones are prominent,” for “then the high inharmonic overtones are prominent,”

Page 132: “a¹ accented-b¹ a¹ accented-b¹” for (compare fourth note) “a¹ accented-b¹ a¹ accented-a¹”

Footnote 18: “struggle to establish the unity of the fatherland.” for “struggle to establish the unity of the father-/land.”