larynx

larynx

a cartilaginous and muscular hollow organ forming part of the air passage to the lungs: in higher vertebrates it contains the vocal cords

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

Larynx

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.

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.

larynx

[′lar‚iŋks]

(anatomy)

The complex of cartilages and related structures at the opening of the trachea into the pharynx in vertebrates; functions in protecting the entrance of the trachea, and in phonation in higher forms.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

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.

REFERENCE

Shmal’gauzen, I. I. Osnovy sravnitel’noi anatomii pozovonochnykh zhivotnykh, 4th ed. Moscow, 1947.

A. N. DRUZHININ

In man, the larynx is the initial section of the respiratory system and the organ of voice production. Being a continuation of the laryngopharynx, the larynx provides for passage of air into the trachea and to a certain extent obstructs the entry of solid and liquid substances. In an adult the larynx is located in the anterior part of the neck, at the level of the fourth to sixth cervical vertebrae, and begins with an opening on the anterior wall of the pharynx. The base of the larynx consists of three unpaired cartilages—epiglottic, thyroid (the largest, forming the laryngeal prominence, or Adam’s apple), and cricoid (located at the boundary with the trachea)—and two paired arytenoid cartilages (located behind, and mobilely joined to, the other cartilages). Three parts are distinguished in the larynx: the entrance, or vestibule, of the larynx; the ventricle, or middle part; and the lower section. The broader upper area is separated from the middle ventricular (false) vocal cords (folds) of mucous membrane, which circumscribe the rima vestibuli. The ventricle and the lower section are delimited by a pair of true vocal cords, between which is the rima glottidis. Overlying the cartilaginous framework of the larynx are the muscles. The largest— the cricothyroid—connects the cricoid and thyroid cartilages and, upon contraction, moves the thyroid cartilage downward, tightening the true vocal cords and narrowing the rima glottidis. Other muscles (the thyroarytenoid, the posterior and lateral cricoarytenoid, and the transverse and oblique arytenoids) are attached to the arytenoid cartilages, but only the posterior cricoarytenoid muscles enlarge the rima glottidis upon contraction. The larynx receives its blood supply from the superior and inferior laryngeal arteries; blood drains into the system of jugular and subclavian veins through the jugular and subclavian veins. The superior and inferior laryngeal nerves—branches of the vagus nerves—provide sensory and motor innervation of the larynx.

V. V. KUPRIIANOV

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.