1, The anterior edge of the larynx. 4, The posterior
face of the thyroid cartilage. 5, 5, The arytenoid cartilages. 6, 6, The
vocal ligaments. 7, Their origin, within the angle of the thyroid
cartilage. 9, Their termination, at the base of the arytenoid cartilages.
8, 10, The glottis.]

594. The larynx is connected by muscles with the sternum, oesophagus,
base of the skull, hyoid bone, lower jaw, and tongue. This organ is
supplied with a large number of blood-vessels, and it likewise
receives nerves from the sympathetic system, and two large nerves from
the tenth pair. The number and size of the nervous filaments
distributed to the mucous membrane of the larynx, render it more
sensitive than any other portion of the respiratory organs.

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How is the glottis enlarged or contracted? Explain fig. 106. 594. By
what means and to what organs is the larynx connected? Why is the
larynx more sensitive than other parts of the respiratory organs?

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595. The larynx is much more developed and prominent in man than in
woman. In the former, the anterior angle of the thyroid cartilage is
acute, while in the latter it is rounded, and the central slope of the
superior border of the same cartilage is less deep, and the epiglottis
smaller and less prominent, than in man.

596. The difference in the formation of the larynx in infancy is less
striking; but at a later period, it is more developed in the male than
in the female. It is very remarkable that this increase is not
progressive, like that of other organs, but, on the contrary, develops
itself at once at the period of puberty.

PHYSIOLOGY OF THE VOCAL ORGANS.

597. In the formation of the voice, each part already described
performs an important office. The cricoid and thyroid cartilages give
form and stability to the larynx; the arytenoid cartilages, by their
movement, vary the width of the glottis. The epiglottis is flexible
and elastic. When it is erect, the chink of the glottis is open, as in
inspiration; when depressed, as in swallowing food and drink, it
covers and closes this aperture. It prevents the introduction of
articles of food into the trachea, and probably modifies sound as it
issues from the glottis.

598. The muscles of the neck elevate and depress the larynx; the
muscles of the larynx increase or diminish the width of the glottis;
at the same time, the vocal cords are relaxed or tightened, while the
mu