larynx(redirected from voice box)
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larynx(lâr`ĭngks), organ of voice in mammals. Commonly known as the voice box, the larynx is a tubular chamber about 2 in. (5 cm) high, consisting of walls of cartilage bound by ligaments and membranes, and moved by muscles. The human larynx extends from the tracheatrachea
principal tube that carries air to and from the lungs. It is about 4 1-2 in. (11.4 cm) long and about 3-4 in. (1.9 cm) in diameter in the adult.
..... Click the link for more information. , or windpipe. In humans, part of the structure may protrude noticeably at the front of the neck, forming the so-called Adam's apple. Within the larynx lie the vocal cords, or vocal folds, a pair of elastic folds in the lining of mucous membrane. During silent breathing, the vocal cords rest along the larynx walls, leaving the air passage fully open. During speech, the cords are stretched across the larynx; air released from the lungs is forced between the cords, causing them to vibrate and so produce voice. Various muscles adjust the tension of the cords as well as the space between them, thus varying the pitch of the sounds produced. The more taut the cords, the higher the pitch. Since men's larynges are usually larger than women's, male vocal cords tend to be longer and the male voice is thus deeper. Growth may double the length of the vocal cords in the male adolescent; hence his dramatic "change of voice." Over the vocal cords extend parallel bands of protective tissue, the false vocal cords. The larynx controls pitch and volume of vocal utterances—it produces initial sounds, while the articulation of these sounds results from the manipulation of teeth, tongue, palate, and lips. Above them, at the opening of the larynx into the throat, hangs the epiglottis, a flap of cartilage that helps to seal off the lower respiratory tract during swallowing so that food and other foreign elements do not enter it.
The complex of cartilages and related structures at the opening of the trachea, or windpipe, into the pharynx, or throat. In humans and most other mammals, the signet-shaped cricoid cartilage forms the base of the larynx and rests upon the trachea. The thyroid cartilage, which forms the prominent Adam's apple ventrally, lies anterior to the cricoid. Dorsally there are paired pivoting cartilages, the arytenoids. Each is pyramid-shaped and acts as the movable posterior attachment for the vocal cords and the laryngeal muscles that regulate the cords. Two other small paired cartilages, the cuneiform and the corniculate, also lie dorsal to the thyroid cartilage. The epiglottis, a leaf-shaped elastic cartilage with its stem inserted into the thyroid notch, forms a lid to the larynx.
the complex of cartilages, muscles, and ligaments that form the initial section of the trachea in terrestrial vertebrates and man, usually containing the vocal apparatus.
The laryngeal cavity is divided into the anterior larynx, or vestibule, and the posterior larynx. The anterior portion of the laryngeal cavity communicates through the respiratory rima with the pharyngeal cavity, and the posterior portion passes into the tracheal cavity. The larynx is derived from the pharynx, and the laryngeal cartilages are transformed gill arches. The arytenoid and cricoid cartilages of the larynx may be distinguished in the majority of caudate and in all acaudate amphibians. In acaudate amphibians, such as frogs, the larynx, merging with the trachea, forms a short laryngotracheal sac. Along the inner edges of the arytenoid cartilages are folds of mucous membrane, separated by the rima glottidis. Below, adhering to the cricoid cartilage, is a half ring formed by the cartilages of the trachea; this whole structure is called the cricotracheal cartilage. In reptiles and birds the same cartilages are present as in the amphibians.
In mammals new cartilages appear in the larynx—the thyroid cartilage and the epiglottis. In the majority of mammals the cricoid cartilage resembles a signet ring, because of the expansion of the dorsal surface. The majority of mammals have, in addition, Santorini’s cartilages at the superior ends of the arytenoid cartilages and Wrisberg’s cartilages along the sides of the anterior edge of the epiglottis. The vocal cords, which are present in most mammals, are drawn between the arytenoid and thyroid cartilages. The structure of the larynx depends upon the character of the animal’s diet and respiration. Thus, in cetaceans and in newborn marsupial mammals, the greatly stretched arytenoid cartilages and the epiglottis form a tube which juts into the choanae behind the soft palate. Such an arrangement of the larynx allows marsupials to breathe and suck milk simultaneously; in cetaceans it prevents water from entering the larynx while food is being swallowed.
REFERENCEShmal’gauzen, I. I. Osnovy sravnitel’noi anatomii pozovonochnykh zhivotnykh, 4th ed. Moscow, 1947.
V. V. KUPRIIANOV