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trachea (trāˈkēə) or windpipe, principal tube that carries air to and from the lungs. It is about 41-2 in. (11.4 cm) long and about 3-4 in. (1.9 cm) in diameter in the adult. It extends from the larynx to the bronchial tubes and is situated in front of the esophagus (see respiration). The trachea consists of a supporting layer of connective and muscular tissue in which are embedded from 16 to 20 U-shaped rings of hard cartilage that encircle the front of the tube. Tiny hairs, or cilia, in the mucous membrane lining keep dust and other foreign particles from entering the lungs. The foreign material becomes trapped in the mucus and is swept by the beating cilia to the nose or mouth, where it is discharged from the body. The air tubes of insects and other arthropods are also called trachea.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



an organ of the respiratory tract in vertebrates, including man, that is situated between the larynx and bronchi.

In amphibians, the trachea is not divided into bronchi, as the lungs start at the trachea. Nor is it separate from the larynx in all species; for example, it is absent in tailless amphibians, where the lungs start at the trachea. In tailed amphibians, the trachea is usually long and has paired cartilages that sometimes grow together.

In reptiles, birds, and mammals, the trachea is distinctly separate from the larynx and is divided into bronchi. The length of the trachea is directly proportional to the length of the neck and inversely proportional to the length of the bronchi. The trachea in reptiles consists of closed or horseshoe-shaped cartilaginous rings, while in birds it usually consists of closed, partially ossified rings, which in some species form numerous windings and widenings that together reverberate sound. In many birds, the lower rings form the syrinx.

In mammals, the trachea consists of cartilaginous half-rings; closed rings are found in beavers, agoutis, flying lemurs, and representatives of the genus Lemur. The dorsal side of the trachea is usually membranous and contiguous with the esophagus. In whales and Sirenia, the cartilages partly fuse together to form a type of spiral. The trachea is usually divided into two bronchi in the thorax. A supplementary bronchus usually branches off the trachea in toothed whales, ruminants, and swine.

The human trachea or windpipe is a direct continuation of the larynx. It is a tube 11–13 cm long, consisting of 16–20 cartilaginous half-rings that are joined by fibrous connective tissue. It is lined with a mucous membrane. The submucous layer contains many mixed mucous glands. Inflammation of the tracheal mucosa is called tracheitis.



(1) A respiratory organ of terrestrial arthropods in the form of an air-conveying tubule that threads through the body and opens at the body surface, forming a spiracle or stigma.

Tracheae are deep invaginations in the body surface and are lined with a thin layer of chitin, which forms a supportive spiral filament that prevents collapse of the tubule walls. In insects and solpugids, extremely slender branchings of the tracheae, tracheoles, thread through the entire body, entwining the organs and even penetrating the interiors of some cells. Thus, oxygen is delivered directly to the site where it is required, and gases are exchanged without the help of a circulatory system.

Many arthropods with highly developed tracheal systems make respiratory movements, such as rhythmic contractions and expansions of the abdomen. In more primitive myriapods and insects, almost all segments of the body have a pair of tracheal bundles and stigmata. In centipedes and most insects, bundles of tracheae that are at first independent later unite as larger longitudinal bundles to form a single respiratory system, and some segments lack stigmata. Many arachnids breathe by means of tracheae, for example, solpugids, phalangids, pseudoscorpions, and many spiders, ticks, and mites. The tracheae and stigmata of these arachnids are located in various parts of the body and are developed independently in the evolutionary process, so that they are not homologous. The tracheae of terrestrial arthropods of other classes also originated independently. In the Onycho-phora, primitive tracheae are represented by numerous bundles of extremely slender tubules, which open into a common stigma; the stigmata are distributed in more or less disorderly fashion throughout the entire body. Some oniscoideans have rudimentary tracheae in the form of tubular branched invaginations on the surfaces of the exopodites of the anterior abdominal legs.

(2) In plants, water-conveying vessels of the xylem.


Dogel’, V. A. Sravnitel’naia anatomiia bespozvonochnykh, part 1. Leningrad, 1938. Pages 411–35.
Beklemishev, V. N. Osnovy sravnitel’noi anatomii bespozvonochnykh, 3rd ed., vol. 2. Moscow, 1964. Pages 54–60.


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


The cartilaginous and membranous tube by which air passes to and from the lungs in humans and many vertebrates.
A xylem vessel resembling the trachea of vertebrates.
(invertebrate zoology)
One of the anastomosing air-conveying tubules composing the respiratory system in most insects.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


1. Anatomy Zoology the membranous tube with cartilaginous rings that conveys inhaled air from the larynx to the bronchi
2. any of the tubes in insects and related animals that convey air from the spiracles to the tissues
3. Botany another name for vessel
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in classic literature ?
Two thumbs pressed into his neck on either side of the windpipe directly on the carotid arteries, shutting off the blood to his brain and giving him most exquisite agony, at the same time rendering him unconscious far more swiftly than the swiftest anaesthetic.
The dog growled again; and licking his lips, eyed Oliver as if he were anxious to attach himself to his windpipe without delay.
He eyed his fair flesh over and over to see where he could best wound it, but all was protected by the goodly armour of which Hector had spoiled Patroclus after he had slain him, save only the throat where the collar-bones divide the neck from the shoulders, and this is a most deadly place: here then did Achilles strike him as he was coming on towards him, and the point of his spear went right through the fleshy part of the neck, but it did not sever his windpipe so that he could still speak.
"I know not," quoth Arthur, smiling, with his head on one side, like a budding lass that is asked to dance, "I know not that I can match our sweet friend's song; moreover, I do verily think that I have caught a cold and have a certain tickling and huskiness in the windpipe."
Without other sound than the scuffing of their bodies on the floor, and the clanking of their armor, they fought, the one to reach the dagger at his side, the other to close forever the windpipe of his adversary.
He chuckled, roared, half suffocated himself by laughing large pieces of beef into his windpipe, roared again, persisted in eating at the same time, got red in the face and black in the forehead, coughed, cried, got better, went off again laughing inwardly, got worse, choked, had his back thumped, stamped about, frightened his wife, and at last recovered in a state of the last exhaustion and with the water streaming from his eyes, but still faintly ejaculating, 'A godfeyther--a godfeyther, Tilly!' in a tone bespeaking an exquisite relish of the sally, which no suffering could diminish.
The good woman, being not a little embarrassed by the novelty of her situation, and certain material apprehensions that perhaps by this time little Jacob, or the baby, or both, had fallen into the fire, or tumbled down stairs, or had been squeezed behind doors, or had scalded their windpipes in endeavouring to allay their thirst at the spouts of tea-kettles, preserved an uneasy silence; and meeting from the window the eyes of turnpike-men, omnibus-drivers, and others, felt in the new dignity of her position like a mourner at a funeral, who, not being greatly afflicted by the loss of the departed, recognizes his every-day acquaintance from the window of the mourning coach, but is constrained to preserve a decent solemnity, and the appearance of being indifferent to all external objects.
Remember that he has the strength of twenty men, and that, though our necks or our windpipes are of the common kind, and therefore breakable or crushable, his are not amenable to mere strength.
Thus, there are two main problems in asthma - the underlying chronic inflammation of the windpipe and occasional symptoms of shortness of breath, cough, chest tightness and wheezing.
Inhaler medication is supposed to go into the windpipe, if it escapes from the nose, asthma symptoms will not be adequately controlled.
The patient suffered severe injuries, including a total rupture of his windpipe.
Summary: Cleveland Clinic Abu Dhabi surgeons repair severed windpipe in emergency operation