SIDE VIEW OF THE VOICEBOX, OR LARYNX, SHOWING THE INTERIOR OF THE LEFT HALF.
| 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. |
It may be observed here that it is impossible to imitate, in the dead subject, the contraction of the vocal muscles. All conclusions, therefore, drawn from experiments upon exsected larynges, with regard to tone-production in living man are necessarily quite untrustworthy, and cannot for one moment be admitted as evidence against observations made upon singers with the laryngoscope.
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.
Plate X.