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Trachea and the main bronchi. Functions, structure

Trachea and the main bronchi.

On the border of VI-VII cervical vertebrae, the larynx passes into the trachea , trachea; In men this level is lower, in women it is higher. In the trachea distinguish the cervical part, pars cervicalis and thoracic part, pars thoracica. The trachea occupies a position in front of the esophagus and in the thoracic cavity behind the large vessels. The length of the trachea is 9-15 cm, width is 1.5-2.7 cm.


At level IV of the thoracic vertebra, the trachea is divided into the main right and left bronchi, the bronchi principales dexter et sinister. The site of the branching of the trachea into two bronchi was called bifurcation of the trachea, bifurcatio tracheae. On the inside, the place of separation is a semilunar protrusion, tracheal carina, carina tracheae, which enters into the cavity of the trachea.


The main bronchi asymmetrically diverge in the sides: the right shorter (3 cm), but the wider one departs from the trachea at an obtuse angle (above it lies the unpaired vein); The left bronchus is longer (4-5 cm), narrower and traces away from the trachea almost at right angles (the aortic arch passes above it).

The trachea of ​​the trachea and the main bronchi are arcuate (more than 2/3 of the circumference) tracheal cartilage, cartilagines tracheales. Their posterior ends are connected by a soft membranous wall adjacent to the esophagus and forming the posterior wall of the trachea and the main bronchi, the so-called membranous wall, paries membranaceus. The number of cartilages of the trachea is 16-20; Right bronchus - 6-8 and left - 9-12. The cartilages are joined together by annular ligaments (tracheal), ligg. Anularia (tracheatia), which posteriorly pass into the membranous wall of the trachea and bronchi. In the membranous wall of the trachea and bronchi, in addition, there are smooth muscle fibers of the longitudinal and transverse direction forming the muscle of the trachea, m. Trachalis.


The external surface of the trachea and bronchi is covered with a connective tissue membrane, tunica adventitia.

The inner surface of the trachea and bronchi is lined with a mucosa, tunica mucosa, which, with the help of a submucous base, tela submucosa, is loose loose with cartilage.

The mucous membrane of the trachea is devoid of folds, covered, as in the larynx, with a multi-row prismatic ciliated epithelium and contains many mucous glands of the trachea, glandulae tracheales; In the bronchial mucosa are the bronchial glands, glandulae bronchiales. Both these and others lie mainly in the submucosa base in the interchondral spaces and the membranous wall of the trachea and bronchi, as well as in a smaller quantity behind the cartilage.

Innervation: rr. Tracheales from n. Laryngeus recurrens (branch n. Vagus) and truncus sympathicus, rr. Bronchiales anteriores et posteriores (n. Vagus).

Blood supply: rr. Tracheales (from a thyroidea inferior), rr. Bronchiales (from aorta thoracica and a. Thoracica interna). Venous blood flows into the venous plexus surrounding the trachea, and then in v. Thyroidea inferior, and by vv. Broncheales in v. Azygos and v. Hemiazygos. Lymphatic vessels are removed
Lymph in the nodi lymphatici cervicales profundi anterior (pretracheales, paratracheales) and laterales (jugulares) and in mediastinales anteriores (tracheobronchiales, paratracheales).

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