The Project Gutenberg eBook of The Mechanism of The Human Voice, by Emil Behnke.

hollow part towards the back, is the Shield cartilage (pl. V, 5), which consists of two plates united in front at an angle which forms the prominence referred to just now as that corner of the triangular funnel (pl. V, 1) which may be both seen and felt in the throat, and which is commonly called the Adam's Apple. It protects the interior and more delicate parts of the voice apparatus, from which circumstance it derives its name of shield cartilage. The plates of the shield have each at the back two horns, the upper and the lower. With the upper horns (pl. VI, 1, 2) the shield cartilage is attached by means of bands (pl. VI, 6, 7) to the corresponding projections (pl. VI, 4, 5) of the tongue-bone (pl. VI, 3), which has the shape of a horseshoe. With the lower horns (pl. V, 8), of which on our diagram we can only see one, it moves upon the ring cartilage as upon a hinge (pl. V, 9).

This is a very particular point, and I beg the reader particularly to notice that if the shield cartilage (pl. V, 5) were gradually drawn downwards and forwards, the space which we now see between the shield and the ring (pl. V, 10) would get smaller and smaller, until at last it quite disappeared; and the distance between the front of the shield (pl. V, 1) and the highest part of the back of the ring (pl. V, 4) would be increased.

I may observe here that authorities differ as to whether the shield moves upon the ring, or the ring upon the shield, and that some maintain the one is drawn down while the other is tipped upward. It is sufficient for our purpose, however, that a movement as upon a hinge takes place, whereby, as explained just now, the distance between the front of the shield and the highest part of the back of the ring is increased.

3rd. The Lid (pl. V, 11) is an elastic cartilage which serves to close the voicebox in the act of swallowing, in order to protect it against any intruding foreign substances. The food we take has to pass over it, and it sometimes happens, when the lid has not been pulled down tight enough, that a particle of food enters the voicebox, in which case we say it has "gone the wrong way," and there is then no peace until the intruder has been got rid of, generally by a violent fit of coughing.

The lid, it is true, is not the only means of protection which the voicebox possesses. Professor C. J. Eberth, for instance, mentions (Archiv für pathol: Anatomie, vol. lxiii., p. 135, Berlin, 1868) the case of a woman who, upon dissection, was found to be entirely without the free upper part of the lid, which could alone cover the voicebox. She had never experienced any difficulty in swallowing, and it is therefore clear that with her the closing of some of the parts immediately below was sufficient to prevent the food from getting into the voicebox. But "the exception proves the rule," and in spite of this and other similar cases, the fact remains that the lid is obviously the first and most natural protector of the voicebox.

4th and 5th. We have thus far become acquainted with three cartilages out of the five. Let us now remove one plate of the shield, as though cutting it off with a knife (pl. VII, 1 and 2), in order that we may look inside and see the remaining two cartilages which have hitherto been hidden by it. These are—

The Pyramids (pl. VII, 1 and 2), so called because of their shape. Their bases are triangular and hollowed out; their sides taper upwards and terminate in points which are bent slightly backwards, and they have each two projections, one pointing forwards (pl. VII, 3) and the other outwards and backwards (pl. VII, 4). It will be convenient to have a special name for the projections pointing outwards and backwards, which we will therefore call the Levers.

The Pyramids are attached with their hollow bases to the borders of the ring (pl. VII, 5), and they are capable of executing rotary movements with surprising freedom and rapidity. Their inner sides may be made to run parallel or to diverge. In addition to this they can be drawn towards each other, or away from each other, so that their summits may either be widely separated or brought close together.

The Vocal Ligaments are two ledges of elastic tissue covered with a very delicate membrane. Each one of them is connected along its whole length, on one side, with the shield cartilage. The vocal ligaments are attached by their hinder ends to those little projections of the pyramids which point forwards (pl. VII, 3, 3), and by their front ends to the centre of the shield (pl. VII, 6), where the two plates meet under a more or less acute angle.

SIDE VIEW OF THE VOICEBOX, OR LARYNX, SHOWING THE INTERIOR OF IT, THE RIGHT PLATE BEING REMOVED.

These vocal ligaments are generally called the vocal cords, but this term is misleading, as it implies strings like those, for instance, of the violin, which are attached only at either end and are free at every other point. This, however, as we have just seen, is not the case, the "Cords" being free only along their inner edges. The name "Vocal Bands," which German physiologists have substituted for "Vocal Cords," does not mend the matter, as it is open to exactly the same objections. The term "Vocal Lips," also used by some writers, is, in my judgment, the most unfortunate of all, because it conveys a totally wrong idea of these parts, as will be seen from a description in another chapter of their movements in the act of singing. I have, therefore, sought for a word which, as a proper description of the thing it is to designate, shall always call a correct image to the reader's mind, and as I cannot find a better one than "Ligament," I have adopted it. I shall consequently in these pages always speak of the tone-producing element as the "Vocal Ligaments."

The vocal ligaments, having met, are struck by the air blown against them from below, and being elastic they yield, allowing themselves to be forced upwards. A little air is thereby set free, and the pressure from below diminished, in consequence of which the vocal ligaments resume their former position, and even move a little more downwards. The renewed pressure of the air once more overcomes the resistance of the vocal ligaments, which again recede as soon as another escape of air has taken place, and this process is repeated in rapid and regular succession. In this manner, and in this manner alone, is vocal tone produced, whether it be called chest, falsetto, head, or by any other name.

There are still some writers who teach a different doctrine. For instance, Miss Sabilla Novello, in her "Voice and Vocal Art," embodied in the "Collegiate Vocal Tutor," published by Novello, Ewer, and Co., says on p. 9, that "The head voice results from the upper [i.e., the false] vocal cords" (these we shall see presently), and on page 13, that the falsetto tones "are created principally by the action of the trachea [windpipe] and not by that of the vocal ligaments." Another writer, Mr. Rumney Illingworth, in a paper "On the Larynx and its Physiology," read before the Royal Medical Society of Edinburgh, on March 3rd, 1879, and communicated to "The Students' Journal and Hospital Gazette" (Vol. IV., No. 91, p. 151), says that "The falsetto voice is produced by the laryngeal sacculi [the pockets of the voicebox, which will be described further on] acting in the same way as a hazel-nut can be made to act as a whistle, when the kernel has been extracted through a small hole in the shell; or as part of the cavity of the mouth acts in whistling." I shall refer to these theories again as the opportunity for their proper discussion arises; for the present I will quote a few authorities on the subject.

Dr. Carpenter, in his "Human Physiology," eighth edition, page 914, says, "The true theory of the voice may now be considered as well established in regard to this essential particular that the sound is the result of the vibrations of the vocal cords," &c.

Professor Marshall, in his "Outlines of Physiology," page 255, says: "Experiments on living animals show that the vocal cords are alone the essential organs for the production of voice, for so long as these remain untouched, although all the other parts in the interior of the larynx be destroyed, the animal is able to emit vocal sounds.... The existence of an opening in the larynx of a living animal, or of man, above the glottis [glottis means the vibrating element of the voicebox] in no way prevents the formation of vocal sound; such an opening if situated in the trachea [windpipe] causes total loss of voice, but by simply closing it, vocal sounds can again be produced. Such openings, in man, are met with, either as the results of accidents, of suicidal attempts, or of operations performed on the larynx or trachea for the relief of disease."

Dr. Tobold, Professor in the University of Berlin, in his "Laryngoscopie and Kehlkopf Krankheiten" (Laryngoscopy and Diseases of the Larynx), p. 131, says, "Soft palate, lid, pockets, and pocket-bands are not directly active in the production of either chest or falsetto tones; they only modify the tone produced in the glottis."

Dr. Luschka, Professor in the University of Tubingen, in his great work "Der Kehlkopf des Menschen" (The Human Larynx), says in the introduction: "Only the vocal cords, with the slit they form, have specifically functional signification, in a narrower sense, of a voice apparatus, as the parts of the larynx which lie under and over them have no material and deciding influence on the production of sound."

I will bring my quotations to a close with the following, which seeks to prove the contrary. Dr. C. B. Garrett ("The Human Voice," J. and J. Churchill, London, 1875, p. 17) says, "It is recorded that the larynx of a blackbird was removed by severing the windpipe just below it; that the poor 'thing continued to sing, though in a feebler tone.' This proves that notes can be formed behind the instrument and before the air reaches it." This argument, however, is of no value, because it so happens that birds have two larynges, one at the bottom and the other at the top of the windpipe. Dr. Garrett seems not to have been aware of this fact.

The vocal ligaments in the adult male are, in a state of rest, about three-quarters of an inch long, and in the female about half an inch. I pointed out before that the vocal ligaments are attached in front to the shield (pl. VII, 6) and behind to the pyramids (pl. VII, 3, 3). Let it now be borne in mind—1st, That the pyramids, in their turn, are fastened to the upper border of the ring cartilage; and 2nd, That by drawing the shield downwards and forwards upon the ring, the distance between the upper border of the ring (pl. VII, 5) and the front of the shield (pl. VII, 6) is increased, and it will be easily seen that this movement must of necessity have the effect of stretching the vocal ligaments.

This drawing of the shield downwards and forwards upon the ring is brought about by a pair of muscles ascending on either side, in the shape of a fan, from the ring to the shield cartilage (pl. VIII, 1, 2). These muscles we name the "Ring-Shield Muscles." In opposition to them there is another pair inside the shield, running parallel with the vocal ligaments (pl. IX, 1, 2, 3). They are attached (like the vocal ligaments) in front to the shield cartilage and behind to the pyramids. These muscles we will call the "Shield-Pyramid Muscles." They counteract the ring-shield muscles, and having overcome their resistance, pull the shield cartilage up again, thereby, of course, relaxing the vocal ligaments. The ring-shield muscles, therefore, stretch the vocal ligaments and the shield-pyramid muscles relax them. The shield-pyramid muscles have an additional function—that of pressing together the vocal ligaments, under certain circumstances, thereby narrowing the opening between them. They have therefore been, in these later days, called the Sphincter [G] muscle of the glottis. They have also been called the Vocal Muscles, since they play so important a part in the formation of all vocal tone that a paralysis of them causes total loss of voice.

These two pairs of muscles, then, namely the ring-shield muscles (pl. VIII, 1, 2) and the shield-pyramid muscles (pl. IX, 1, 2, 3) by stretching, slackening, and compressing the vocal ligaments, mainly govern the pitch of the tones produced by their vibrations. The ring-shield muscles receive some assistance in stretching the vocal ligaments from another quarter, of which we shall speak later on.

We have now had a look at the vocal ligaments, and we have seen by what means they are put on the stretch. As, however, in a state of repose these ligaments diverge behind, they must be brought parallel to each other before they are ready for the production of sound. Let us, therefore, in order to explain how this is done, imagine that we have cut off that part of the pyramids which is standing out above the vocal ligaments (pl. VII), and let us now have a look at these parts from above. You see the ligaments (pl. X A, 1, 2), a section of the pyramids (pl. X A, 3, 4), and uniting these an elastic band (pl. XA, 5). The space between these parts is commonly called the Glottis, but as this appellation belongs more properly to the vocal ligaments, it is manifestly wrong to give the same name to the space which they inclose. This space should be distinguished as the "Chink of the Glottis" or the "Vocal Chink."

I have been blamed for making this distinction in the face of almost universal usage. But I can point to the great anatomist Professor Luschka as having set the example, and while it is true that in most physiological works "Glottis" is used for the slit between the vocal ligaments, yet the appellations "Rima glottidis" and "Aperture of the glottis" are also employed for the same thing. Medical men, moreover, speak of "Spasm of the glottis," and singing masters of the "Shock of the glottis," which terms are clearly quite meaningless when applied to a space.

Dr. Garrett says, on page 12 of the book quoted before, that "The upper portion of the larynx above the false vocal cords is termed the glottis." He might as well say, "The upper portion of the face above the nose is termed the mouth." I really should not notice so astounding a statement were it not made by one signing himself an M.D., and published by so eminent a firm of Medical publishers as Messrs. J. and A. Churchill.

On plate XI you see all parts in a state of rest. To the levers of the pyramids (pl. XI, 1, 2) a pair of muscles is attached, the bases of which are fixed upon the back of the ring cartilage below (pl. XI, 3, 6, 3). The action of these "Back Ring-Pyramid Muscles" (pl. XI, 4, 1 and 5, 2) is to contract as soon as we take breath, thereby drawing together the pyramids behind and separating them in front, at the same time stretching the elastic band behind (pl. X, A, 5). By this movement the chink of the glottis is thrown wide open into the shape depicted on pl. X, B. During expiration these relax, the elastic band contracts, and the vocal chink resumes the shape as on pl. XI. These movements go on from the beginning of our lives to the end, whether we are asleep or awake, with more or less vigour, according as we take a slight or a deep inspiration. The back ring-pyramid muscles (pl. XI, 4, 1 and 5, 2), have consequently the all-important function of keeping open the gate through which the air we breathe enters the lungs. They have, therefore, been poetically called the "Guardians of the Portal of Life." By their action of pulling the pyramids backwards, they also assist the ring-shield muscles (pl. VIII, 1, 2) in stretching the vocal ligaments.

In opposition to these "Opening Muscles" there is another pair rising from the side borders of the ring (pl. XI, 3, 3) which are fastened to the front part of the levers of the pyramids (pl. XI, 1, 2), serving to draw together their front projections to which the vocal ligaments are attached, and which are thereby brought parallel with each other.

Note.—The shield-pyramid muscles (Thyro-Arytenoidei) which run parallel with the vocal ligaments are, for the sake of clearness, omitted from this diagram.

These "Side Ring-Pyramid Muscles" (pl. XI, 3, 1 and 3, 2; see also pl. IX, 5, 4) are assisted by a single muscle uniting the pyramids behind the elastic band which we have already noticed. This muscle we will call the "Pyramid Muscle" (pl. XI, 7). By the united action of the muscles which have just been described the vocal chink is thrown in the shape shown on pl. X, C, and the vocal ligaments are now in a proper position for the production of tone.

Before proceeding any farther it will be well if we once more glance at the muscles with which we have become acquainted, so that we may be quite sure about their functions.

The Pocket Ligaments (called "False Vocal Cords," pl. XII, 1 and 2) are a pair of horizontal projections running above and parallel with the vocal ligaments (pl. XII, 3 and 4). The pocket ligaments are, like the vocal ligaments, attached in front to the shield and behind to the pyramids. They may be described as two ledge-shaped pads mainly formed of glands. They are very sensitive and movable, and ready on the smallest incitement to meet with great rapidity in order to protect the vocal ligaments from any harm. They must, therefore, be chiefly regarded as safeguards of the vocal apparatus, though it is probable that by breaking the stream of air passing through the chink of the glottis, they also exercise considerable influence upon the quality of the tone emitted. It may be affirmed, however, without the slightest hesitation, that they have absolutely nothing to do with the production of tone. We shall see these glandular ledges again during our observations upon the living subject, and I shall therefore say no more about them at present.

The space between the pocket ligaments and the vocal ligaments (pl. XII, 1, 2, 3, 4) is the entrance to two pouches or pockets which extend outwards and upwards. The dimensions of these pockets vary very much in different individuals. As a rule their height does not exceed two-fifths of an inch, so that their terminations do not reach the upper borders of the shield cartilage (pl. XII, 5 and 6). But there are instances in which the pockets are nearly three-quarters of an inch high, and where such is the case they, as a necessary consequence, reach beyond the shield. Sometimes they are so high as nearly to touch the root of the tongue. Their outer walls are chiefly formed of loose fatty cellular tissue, and the pockets are almost entirely surrounded by a large number of small glands.

Now these are the "Laryngeal sacculi" which, according to Mr. Illingworth, produce the falsetto voice by "acting in the same way as a hazel-nut can be made to act as a whistle, when the kernel has been extracted through a small hole in the shell," &c. I think, however, that the reader will, from the description given above, agree with me that the acoustic properties of the pockets of the voicebox cannot be very great, and that, at all events, there is a vast difference between their construction and that of a hazel-nut, either with or without the kernel. Then there is this additional difficulty, that even if one could whistle upon the pockets in the manner suggested, there are two of them, covered, let it be remembered, with a multitude of glands, continually producing moisture, and liable to enlarge or to diminish. How, I should like to know, could two such cavities be so tuned as under any circumstances to produce exactly the same tones? Would not rather frightful discords be the inevitable result? And again, what provision is there in the pockets for the gradations of pitch? But quite apart from these considerations, this and other similar theories are completely disproved by the fact that every tone which the human voice is capable of producing can be produced by inspiration as well as by expiration. The tones sung by inspiration are, as might be expected, wholly devoid of beauty, because the vocal apparatus is, as it were, put upside down, and the position of bellows and resonator reversed. But that does not alter the question. The fact remains, and clearly proves that the pockets have no more to do with the falsetto than with the chest voice, because in inspiration the air strikes the vocal ligaments after it has passed the pockets, and yet the result is, beauty of tone apart, exactly the same.

The function of the pockets, in my opinion, is this: They are the means of isolating the vocal ligaments, thus enabling them to vibrate freely and without hindrance. They also allow the sound-waves to expand sideways, thereby materially adding to their resonance. Lastly, they with their many little glands produce and supply the vocal ligaments with that moisture without which, according to the investigations of J. Müller,[H] the production of tone cannot be carried on.

Above the pocket ligaments there is a kind of tube which is formed by the upper part of the pyramids (surmounted by two little bodies called the cartilages of Santorini, pl. XII, 7, 8) behind; the lid or epiglottis (pl. XII, 9) in front, and sideways by two folds of mucous membrane running up from the pyramids to the lid (pl. XII, 14, 10 and 15, 11). These folds are in many cases supported by two small cartilages, which we will call the Wedges (pl. XII, 12, 13). These, according to Madame Emma Seiler, are the chief factors in the formation of the highest register of the female voice. In some physiological works they are treated as of very little consequence, and in others they are not mentioned at all.

These wedges are two thin strips of cartilage running in front of the pyramids (pl. XII, 12 and 13) where they are embedded in a number of glands. Their upper ends terminate in the cartilages of Wrisberg (pl. XII, 14, 15), and their lower ends gradually dwindle away in the direction of the vocal ligaments.

Madame Seiler says that they "reach to the middle of the vocal chords, by which they are enveloped."[I] She comments in the same book on the fact that German anatomists have been reluctant to admit the existence of these cartilages; and she adds on page 61, "It was, therefore, a great satisfaction to me to find them described under the name of the cuneiform cartilages in Wilson's 'Human Anatomy.'" It must be confessed, however, that Wilson's description of them is totally different from Madame Seiler's. He says, "The cuneiform cartilages are two small cylinders of yellow fibro-cartilage, about seven lines in length and enlarged at each extremity. By the lower end or base the cartilage is attached to the middle of the external surface of the arytenoid (the pyramid), and by its upper extremity forms a prominence in the border of the aryteno-epiglottidean fold of membrane"[J] (i.e., the fold running up to the lid). According to Seiler, therefore, the wedges reach from the pyramids to the middle of the vocal ligaments, but according to Wilson their bases are attached to the middle of the outer surface of the pyramids, so that they cannot even touch the vocal ligaments. As Madame Seiler assigns very important functions to these wedges in the formation of the highest register of the female voice, and as she quotes Wilson in a manner that must lead the reader to suppose he gave a similar description to hers of these cartilages, I have thought it right to give Wilson's statement in full.

But there is a description of these cartilages by Dr. Witkowski which corresponds very closely with Madame Seiler's. Speaking of some of the glands of the voicebox, he says in the work mentioned before, on p. 12—"They are arranged in the form of an L, whose vertical branch goes along the arytenoid cartilages (the pyramids), the horizontal branch following the direction of the vocal cords. There is often found situated in the midst of this group of glands the cuneiform cartilage of Wrisberg, sometimes reduced to a mere cartilaginous granule."

Dr. Elsberg also describes them on p. 37 of the treatise before mentioned as "elongated nodules" in the hinder portion of the vocal ligaments, and says they are found "more often in the female than in the male sex." He calls them the "posterior vocal nodules," and gives on p. 36 a diagram which shows them most clearly and unmistakably. This point would therefore seem to be settled.

The Resonator.—We now come to the last part of our instrument, namely, the resonator, which is formed of (1) the pockets of the larynx; (2) the tube above the pocket ligaments; (3) the upper part of the throat; (4) the mouth; and (5) the nose. Before giving a description of the resonator, it will be necessary to make a few introductory remarks on certain laws of the philosophy of sound, which have been so clearly demonstrated that they admit of no contradiction.

The Loudness of tone depends upon the amplitude of the vibrations. This is easily shown by drawing a bow over the string of a violin: while the vibrations of the string are largest, the tone produced is loudest, and as the vibrations get smaller, so the tone becomes fainter.

The Pitch of tone depends upon the number of vibrations in a given period of time. The greater the number of vibrations the higher the pitch, and vice versâ.

The Quality of tone depends on the form of the vibrations, "which also determines the occurrence of upper partial tones."[K]

Now, to make the sound of any tone-producing element more intense, and to give it some special quality, is the work of the resonator. If we simply fix a fiddle string at either end, and, after giving it a certain amount of tension, draw a bow across it, we shall certainly produce a tone, but a very poor and faint one. Put the same string with the same amount of tension upon a cheap violin, and the tone will be intensified, and its quality changed, though that quality may be of a very unpleasant kind. Repeat the experiment upon an Amati or a Straduarius, and not only will the tone be more powerful still, but it will also have a full, round, and beautiful quality. Something, it is true, depends upon the string and upon the bowing, but we are here supposing the same string and the same player, our object being to show how the resonator, which, in this case, is the body of the violin, intensifies the tone of the string, and affects its quality.

Illustrations exemplifying the same thing might be multiplied to any extent, but the one I have just given will suffice. As with the string, so with the vocal ligaments. Cut a larynx out of a dead body, put it in proper position on the top of a bellows, and force the air through it, and you will produce tone, but faint and poor tone. Now add a resonator to the larynx, and the tone of the vocal ligaments will be intensified, and its quality altered according to the kind of resonator you make use of.

It is clear, therefore, that the human voice does not only depend upon the vibrations of the vocal ligaments, and the corresponding vibrations of the air passing between them, but also upon the resonator as defined on p. 9. According to the natural formation of our resonator, and according to the infinite variety of shapes which every one has it in his power to give to it, our voices will be, always supposing the conditions of the vocal ligaments to be the same, either full, round, sonorous, and beautiful, or they will be poor, cutting, muffled, guttural, nasal, and ugly.

As we have, or may easily acquire, absolute command over the resonator, or, at least, over the greatest part of it, it is a comfort to know that so very much depends upon it, and I trust my readers will now, with some amount of pleasure, look with me at this part of the vocal apparatus.

The 1st and 2nd divisions of the resonator—namely, the pockets of the larynx and the tube above the pocket ligaments—have been fully described on pp. 52, 53, and no more need be said on the subject here.

The upper part of the throat, called in scientific works the "Pharynx" (pl. I, P), is a cavity, the largest part of which may be seen through the arch at the back of the open mouth. Its hinder wall is formed by the spinal column, and it extends upwards as far as the Eustachian tubes (pl. I, E) which communicate with the middle part of the ear. Here it joins—

The Cavities of the Nose (pl. I, N), which have for their base the hard and soft palate (pl. I, H and S), and which are divided by a bone partition.

The only part of the Mouth which requires a particular description is the soft palate. This is a movable partition by means of which either the mouth or the nose can be completely separated from the throat. If the nose is to be shut off from the throat the soft palate is raised, and pressed against the back of the pharynx. If the mouth is to be shut off the soft palate is lowered, and rests closely upon the back of the tongue. This partition plays a most important part in vocalization. In the formation of all pure vowel sounds it is raised, thereby closing the nasal cavities, and it has been found that the closure is loosest for "ah" (as in "father") and tightest for "e" (as in "bee"), the intermediate vowels being "a" (as in "name"), "oh" and "oo" (as in "food"). This has been clearly shown by Czermak in the following manner. Lying down on his back, he had the nasal cavities filled with tepid water. He then uttered the various vowel sounds, and ascertained from the quantity of water required to force open the closure formed by the soft palate the degree of tightness for each vowel. He afterwards constructed a very ingenious little apparatus, by means of which, in one of his lectures, he demonstrated this fact to his audience. It will be easily understood from the above explanation that, if the closure of the nasal cavities is sufficiently imperfect to allow any considerable amount of air to pass through the nose, the result will be a nasal tone.

1.	Front Corner of the Voicebox (Larynx).
2.	Ring (Cricoid) Cartilage.
3, 4.	Upper Border of the Ring.
5.	Shield (Thyroid) Cartilage.
6, 7.	Upper Horns of the Shield.
8.	Right Lower Horn of the Shield.
9.	Point where the Shield moves upon the Ring.
10.	Ring-Shield (Crico-thyroid) Aperture covered by Membrane.
11.	Lid (Epiglottis).
12.	Windpipe (Trachea).

1, 2.	Upper Horns of the Shield.
3.	Tongue (Hyoid) Bone.
4, 5.	Horns of the Tongue-Bone.
6, 7.	Bands uniting the Shield with the Tongue-Bone.
8, 9.	Lid.
10, 11.	Plates of the Shield.
12.	Ring.
13.	Elastic Band uniting the Shield with the Ring.
14.	Windpipe.

1, 2.	Pyramids (Arytenoid Cartilages).
3, 3.	Front Projections of the Pyramids.
4.	Lever of the Right Pyramid.
5.	Upper Border of the Ring.
6, 3, 3.	Vocal Ligaments.
7.	Lid.
8.	Shield.
9.	Left Upper Horn of the Shield.
10.	Ring.
11.	Windpipe.

1, 2.	Ring-Shield Muscle (Crico-Thyroideus).
3.	Lid.
4.	Shield.
5, 6.	Upper Horns of the Shield.
7.	Ring.
8.	Windpipe.

1, 2, 3.	Shield-Pyramid Muscle (Thyro-Arytenoideus).
4, 5.	Ring-Pyramid Muscle (Crico-Arytenoideus).
6.	Shield.
7.	Left Upper Horn.
8.	Pyramid.
9.	Ring.
10.	Windpipe.

C.	Glottis in the Production of Sound.
A. 1, 2.	Vocal Ligaments.
3, 4.	Section of the Pyramids.
5.	Elastic Band.
6, 7.	Levers of the Pyramids.

1, 2.	Section of the Pyramids with Vocal Ligaments and Elastic Band.
3, 6, 3.	Ring.
7.	Pyramid Muscle (Arytenoideus Transversus).
8, 9, 10.	Shield.
11.	Bands by means of which the Pyramids are attached to the Ring.
4 & 5.	Back Ring-Pyramid Muscles (Posterior Crico-Arytenoidei).
1, 3 & 2, 3.	Side Ring-Pyramid Muscles (Lateral Crico-Arytenoidei).

1, 2.	Pocket Ligaments (False Vocal Cords).
3, 4.	Vocal Ligaments (Vocal Cords).
5, 6.	Shield (Thyroid) Cartilage.
7, 8.	Cartilages of Santorini.
9.	Lid (Epiglottis).
14, 10 & 15, 11.	Folds of Mucous Membrane (Aryteno-Epiglottic Folds).
12, 13.	Wedges (Cuneiform Cartilages).
14, 15.	Cartilages of Wrisberg.
16, 17.	Pyramid Muscle (Arytenoideus Transversus).
18, 19.	Ring (Cricoid) Cartilage.
20, 21.	Tongue (Hyoid) Bone.