The bronchi are part of the pathways that conduct air. Representing tubular branches of the trachea, they connect it with the respiratory tissue of the lung (parenchyma).

At the level of the 5-6 thoracic vertebrae, the trachea is divided into two main bronchi: right and left, each of which enters its corresponding lung. In the lungs, the bronchi branch, forming a bronchial tree with a colossal cross-sectional area: about 11,800 cm2.

The sizes of the bronchi differ from each other. So, the right one is shorter and wider than the left one, its length is from 2 to 3 cm, the length of the left bronchus is 4-6 cm. Also, the sizes of the bronchi differ by gender: in women they are shorter than in men.

The upper surface of the right bronchus is in contact with the tracheobronchial lymph nodes and azygos vein, the posterior surface is in contact with the vagus nerve itself, its branches, as well as the esophagus, thoracic duct and posterior right bronchial artery. The lower and anterior surfaces contain the lymph node and pulmonary artery, respectively.

The upper surface of the left bronchus is adjacent to the aortic arch, the posterior surface is adjacent to the descending aorta and branches of the vagus nerve, the anterior surface is adjacent to the bronchial artery, and the lower surface is adjacent to the lymph nodes.

Structure of the bronchi

The structure of the bronchi differs depending on their order. As the diameter of the bronchus decreases, their shell becomes softer, losing cartilage. However, there is also common features. There are three membranes that form the bronchial walls:

• Mucous. Covered with ciliated epithelium, located in several rows. In addition, several types of cells were found in its composition, each of which performs its own functions. Goblet forms a mucous secretion, neuroendocrine secretes serotonin, intermediate and basal ones take part in the restoration of the mucous membrane;
• Fibromuscular cartilage. Its structure is based on open hyaline cartilaginous rings, fastened together by a layer of fibrous tissue;
• Adventitial. A shell formed by connective tissue that has a loose and unformed structure.

Functions of the bronchi

The main function of the bronchi is to transport oxygen from the trachea to the alveoli of the lungs. Another function of the bronchi, due to the presence of cilia and the ability to form mucus, is protective. In addition, they are responsible for the formation of the cough reflex, which helps eliminate dust particles and other foreign bodies.

Finally, the air, passing through a long network of bronchi, is moistened and warmed to the required temperature.

From here it is clear that treatment of bronchi in diseases is one of the main tasks.

Bronchial diseases

Some of the most common bronchial diseases are described below:

• Chronic bronchitis is a disease in which inflammation of the bronchi and the appearance of sclerotic changes in them are observed. It is characterized by a cough (constant or periodic) with sputum production. Its duration is at least 3 months within one year, and its duration is at least 2 years. There is a high probability of exacerbations and remissions. Auscultation of the lungs allows one to determine hard vesicular breathing, accompanied by wheezing in the bronchi;
• Bronchiectasis is an expansion that causes inflammation of the bronchi, degeneration or sclerosis of their walls. Often, based on this phenomenon, bronchiectasis occurs, which is characterized by inflammation of the bronchi and the occurrence of a purulent process in their lower part. One of the main symptoms of bronchiectasis is a cough, accompanied by the release of copious amounts of sputum containing pus. In some cases, hemoptysis and pulmonary hemorrhage are observed. Auscultation allows you to determine weakened vesicular breathing, accompanied by dry and moist rales in the bronchi. Most often, the disease occurs in childhood or adolescence;
• at bronchial asthma heavy breathing is observed, accompanied by suffocation, hypersecretion and bronchospasm. The disease is chronic and is caused either by heredity or by previous infectious diseases respiratory organs (including bronchitis). Attacks of suffocation, which are the main manifestations of the disease, most often bother the patient at night. Tightness in the chest area is also often observed, sharp pains in the area of ​​the right hypochondrium. Adequately selected treatment of the bronchi for this disease can reduce the frequency of attacks;
• Bronchospastic syndrome (also known as bronchospasm) is characterized by spasm of bronchial smooth muscle, causing shortness of breath. Most often it is sudden and often turns into a state of suffocation. The situation is aggravated by the release of secretions from the bronchi, which impairs their patency, making it even more difficult to inhale. As a rule, bronchospasm is a condition accompanying certain diseases: bronchial asthma, chronic bronchitis, emphysema.

Methods for studying the bronchi

The existence of a whole set of procedures that help assess the correct structure of the bronchi and their condition in diseases allows one to select the most adequate treatment for the bronchi in a given case.

One of the main and proven methods is a survey, in which complaints of cough, its features, the presence of shortness of breath, hemoptysis and other symptoms are noted. It is also necessary to note the presence of factors that negatively affect the condition of the bronchi: smoking, working in conditions of increased air pollution, etc. Special attention should be addressed appearance patient: skin color, chest shape and other specific symptoms.

Auscultation is a method that allows you to determine the presence of changes in breathing, including wheezing in the bronchi (dry, wet, medium-bubbly, etc.), breathing hardness, and others.

With the help of X-ray examination, it is possible to detect the presence of expansions of the roots of the lungs, as well as disturbances in the pulmonary pattern, which is characteristic of chronic bronchitis. characteristic feature bronchiectasis is the expansion of the lumen of the bronchi and thickening of their walls. Bronchial tumors are characterized by local darkening of the lung.

Spirography is a functional method for studying the condition of the bronchi, allowing one to assess the type of violation of their ventilation. Effective for bronchitis and bronchial asthma. It is based on the principle of measuring the vital capacity of the lungs, forced expiratory volume and other indicators.

The trachea is a non-collapsing tube that starts from the lower end of the larynx and goes into the chest cavity, where at the level of the V-VII thoracic vertebrae it divides into the right and left main bronchi, forming a fork - the bifurcation of the trachea. In the area of ​​division of the trachea, a spur protrudes into its lumen, deflected to the left side, so the passage into the right bronchus is wider. There is a short cervical part and a longer chest part. The length of the trachea is 8-13 cm, the diameter is 1.5-2.5 cm. In men, the trachea is longer than in women. In newborns, the trachea is relatively short, its bifurcation is located at the level of the III-IV thoracic vertebrae and has a fusiform shape. Tracheal growth occurs rapidly in the first 6 months and then slows down until 10 years of age. By the age of 14-16, the length of the trachea doubles, and by the age of 25 it triples.

Structure of the trachea. The tracheal wall is formed by 16-20 hyaline tracheal cartilages, which have the appearance of incomplete cartilaginous rings. The tracheal cartilages are connected to each other by annular ligaments. At the back, between the ends of the tracheal cartilages, a membranous wall of the trachea is formed, consisting of bundles of smooth muscle tissue, located mainly circularly and partially longitudinally. The tracheal muscle causes active changes in the lumen of the trachea during breathing and coughing.

On the outside, the trachea is covered with a thin outer connective tissue membrane, and on the inside by a mucous membrane, which is tightly connected to the tracheal cartilage and ligaments and does not form folds. It is covered, like the larynx, with multi-row ciliated epithelium, between the cells of which there are many goblet-shaped mucous cells. The proper layer of the mucous membrane contains protein-mucosal tracheal glands and lymphatic follicles.

Topography of the trachea. The trachea is projected at the level from the upper edge of the VII cervical to the IV-VII thoracic vertebrae. In people with wide chest the projection of the tracheal bifurcation falls on the VI-VII thoracic vertebrae, and in people with a narrow chest - on V.

The anterior surface of the cervical part of the trachea is adjacent to the isthmus thyroid gland, to the sternohyoid and sternothyroid muscles, posterior - to the esophagus, lateral - to the lobes of the thyroid gland and neurovascular bundles of the neck. The aortic arch with its branches is adjacent to the anterior surface of the thoracic part of the trachea, the esophagus and pericardium are adjacent to the posterior surface, the azygos vein and the right vagus nerve are located to the right lateral surface. The lymph nodes, to the left lateral - the aortic arch, the left recurrent nerve and lymph nodes.

The blood supply to the cervical part of the trachea is provided by the inferior thyroid arteries. The thoracic part receives branches from the bronchial and esophageal arteries. The outflow of venous blood occurs into the inferior thyroid, azygos and semi-gypsy veins.

Lymph flows through the lymphatic vessels into the tracheal and tracheobronchial nodes.

Innervation is carried out by branches of the cervicothoracic nerve plexus.

The main (primary) bronchi, right and left, depart from the trachea, forming its bifurcation, and go to the corresponding lung, where they are divided into bronchi of the second, third and other orders, which, increasingly decreasing in caliber, form the bronchial tree. As the bronchi branch, they lose cartilage, so that the basis of the walls of the small bronchi consists mainly of elastic and smooth muscle fibers. The angle between the trachea and the right bronchus is usually 150-160°, and between the trachea and the left bronchus - 130-140°. The right bronchus is shorter and wider than the left. The length of the right bronchus is 1-2 cm, and the diameter is 1.5-2.5 cm. It usually consists of 6-8 cartilaginous rings. The length of the left bronchus is 4-6 cm, and the diameter is 1-2 cm; it is composed of 9-12 cartilaginous rings. Due to the fact that the right bronchus occupies a more vertical position and is wider than the left, foreign bodies respiratory tract most often enter the right bronchus. The structure of the bronchi is similar to the structure of the trachea.

In women, the bronchi are somewhat narrower and shorter than in men. In newborns, the bronchi are wide, along with cartilaginous half-rings there are also hyaline plates. The mucous membrane is thin, covered with cubic epithelium. The mucous glands are poorly developed. The bronchi grow especially rapidly in the first year of life, and then more slowly until the age of 10. By the age of 13, the length of the bronchi doubles. After 40 years, the rings begin to slightly calcify.

Topography of the bronchi. The right bronchus with its upper surface is adjacent to the azygos vein and tracheobronchial lymph nodes, the posterior surface is adjacent to the right vagus nerve, its branches and the posterior right bronchial artery, the anterior surface is adjacent to the ascending aorta, the anterior bronchial artery and the pericardium, and the lower surface is adjacent to the bifurcation lymph nodes. The left bronchus is adjacent to the aortic arch from above, from behind - to the descending aorta, the left vagus nerve, its branches and to the esophagus, in front - to the left anterior bronchial artery, tracheobronchial nodes, from below - to the bifurcation lymph nodes.

The structure of the respiratory tract provides direct and open communication with atmospheric air, which, in contact with the warm, moist and mucous membrane, is warmed, moistened and freed from dust particles, which are moved upward by the ciliated epithelium and are removed outward with coughing and sneezing. Microbes are neutralized here by the activity of wandering cells of the lymphatic follicles, scattered in large numbers in the mucous membrane.

The smooth muscles of the bronchi are supplied with centrifugal fibers of the vagus and sympathetic nerves. The vagus nerves cause contraction of the bronchial muscles and narrowing of the bronchi, while the sympathetic nerves relax the bronchial muscles and dilate the bronchi.

The trachea, trachea (from the Greek trachus - rough), being a continuation of the larynx, begins at the level of the lower edge of the VI cervical vertebra and ends at the level of the upper edge of the V thoracic vertebra, where it is divided into two bronchi - right and left. The place where the trachea divides is called bifurcatio tracheae. The length of the trachea ranges from 9 to 11 cm, the transverse diameter is on average 15 – 18 mm.

Topography of the trachea.

The cervical region is covered at the top by the thyroid gland, at the back the trachea is adjacent to the esophagus, and on the sides of it are the common carotid arteries. In addition to the isthmus of the thyroid gland, the trachea is also covered in front mm. sternohyoideus and sternothyroideus, except in the midline where the inner edges of these muscles diverge. The space between the posterior surface of these muscles with the fascia covering them and the anterior surface of the trachea, spatium pretracheale, is filled with loose fiber and blood vessels thyroid gland (a. thyroidea ima and venous plexus). Thoracic the trachea is covered in front by the manubrium of the sternum, thymus gland, vessels. The position of the trachea in front of the esophagus is associated with its development from the ventral wall of the foregut.

Structure of the trachea.

The tracheal wall consists of 16 - 20 incomplete cartilaginous rings, cartilagines tracheales, connected by fibrous ligaments - ligg. annularia; each ring extends only two-thirds of the circumference. The posterior membranous wall of the trachea, paries membranaceus, is flattened and contains bundles of unstriated muscle tissue that run transversely and longitudinally and provide active movements of the trachea during breathing, coughing and m. n. The mucous membrane of the larynx and trachea is covered with ciliated epithelium (with the exception of the vocal cords and part of the epiglottis) and is rich in lymphoid tissue and mucous glands.

Vessels and nerves.

The trachea receives arteries from the aa. thyroidea inferior, thoracica interna, as well as from rami bronchiales aortae thoracicae. Venous drainage is carried out into the venous plexuses surrounding the trachea, as well as (and especially) into the veins of the thyroid gland. The lymphatic vessels of the trachea along their entire length go to two chains of nodes located on its sides (peritracheal nodes). In addition, from the upper segment they go to the preglottic and upper deep cervical, from the middle to the last and supraclavicular, from the lower to the anterior mediastinal nodes.

The tracheal nerves originate from the truncus sympathicus and n. vagus, as well as from the latter’s vegwi – n. laryngeus inferior.

The main bronchi, right and left, bronchi principales (bronchus, Greek - respiratory tube) dexter et sinister, depart at the site of the bifurcatio tracheae almost at a right angle and are directed to the gate of the corresponding lung. The right bronchus is slightly wider than the left, since the volume of the right lung is larger than the left. At the same time, the left bronchus is almost twice as long as the right one; there are 6–8 cartilaginous rings in the right one, and 9–12 in the left one. The right bronchus is located more vertically than the left, and thus is like a continuation of the trachea. V. is thrown through the right bronchus in an arcuate manner from back to front. azygos, heading towards v. cava superior, the aortic arch lies above the left bronchus. The mucous membrane of the bronchi is identical in structure to the mucous membrane of the trachea.

In a living person, during bronchoscopy (i.e., when examining the trachea and bronchi by inserting a bronchoscope through the larynx and trachea), the mucous membrane has a grayish color; cartilaginous rings are clearly visible. The angle at the site of division of the trachea into bronchi, which looks like a ridge protruding between them, crista, should normally be located in the midline and move freely during breathing.

Bronchi Trachea(windpipe) - an unpaired organ (10-13 cm), which serves to pass air into the lungs and back, begins at the lower edge of the cricoid cartilage of the larynx. The trachea is formed by 16-20 half rings of hyaline cartilage. The first half-ring is connected to the cricoid cartilage by the cricotracheal ligament. The cartilaginous half-rings are connected to each other by dense connective tissue. Behind the rings there is a connective tissue membrane (membrane) mixed with smooth muscle fibers. Thus, the trachea is cartilaginous in front and on the sides, and connective tissue in the back. The upper end of the tube is located at the level of the 6th cervical vertebra. The lower one is at the level of 4-5 thoracic vertebrae. The lower end of the trachea divides into two main primary bronchi, the site of division is called the tracheal bifurcation. Due to the presence of elastic fibers in connective tissue between the semirings, the trachea can lengthen when the larynx moves up and shorten when it moves down. The submucosal layer contains numerous small mucous glands.

Bronchi are a continuation of the windpipe, both functionally and morphologically. The walls of the main bronchi consist of cartilaginous half-rings, the ends of which are connected by a connective tissue membrane. The right main bronchus is shorter and wider. Its length is about 3 cm, consists of 6-8 half rings. The left main bronchus is longer (4-5 cm) and narrower, consisting of 7-12 half rings. The main bronchi enter the gate of the corresponding lung. The main bronchi are the bronchi of the first order. From them depart bronchi of the 2nd order - lobar (3 in the right lung and 2 in the left), which give rise to segmental bronchi (3 orders), and the latter branch dichotomously. In the segmental bronchi there are no cartilaginous half-rings; the cartilage breaks up into separate plates. The segments are formed by pulmonary lobules (up to 80 pieces in 1 segment), which include the lobular bronchus (8th order). In small bronchi (bronchioles) with a diameter of 1-2 mm, cartilaginous plates and glands gradually disappear. Intralobular bronchioles break up into 18-20 terminal bronchioles with a diameter of about 0.5 mm. In the ciliated epithelium of the terminal bronchioles there are individual secretory cells (Clark), which produce enzymes that break down surfactant. These cells are also the source of restoration of the epithelium of the terminal bronchioles. All bronchi, starting from the main bronchi and including the terminal bronchioles, make up the bronchial tree, which serves to conduct a stream of air during inhalation and exhalation; respiratory gas exchange between air and blood does not occur in them.

64. Trachea and bronchi: topography, structure, functions, blood supply, innervation, regional lymph nodes.

Bronchi Trachea (trachea) (windpipe) - an unpaired organ (10-13 cm), which serves to pass air into the lungs and back, begins at the lower edge of the cricoid cartilage of the larynx. The trachea is formed by 16-20 half rings of hyaline cartilage. The first half-ring is connected to the cricoid cartilage by the cricotracheal ligament. The cartilaginous half-rings are connected to each other by dense connective tissue. Behind the rings there is a connective tissue membrane (membrane) mixed with smooth muscle fibers. Thus, the trachea is cartilaginous in front and on the sides, and connective tissue in the back. The upper end of the tube is located at the level of the 6th cervical vertebra. The lower one is at the level of 4-5 thoracic vertebrae. The lower end of the trachea divides into two main primary bronchi, the site of division is called the tracheal bifurcation. Due to the presence of elastic fibers in the connective tissue between the semi-rings, the trachea can lengthen when the larynx moves up and shorten when it moves down. The submucosal layer contains numerous small mucous glands.

Bronchi are a continuation of the windpipe, both functionally and morphologically. The walls of the main bronchi consist of cartilaginous half-rings, the ends of which are connected by a connective tissue membrane. The right main bronchus is shorter and wider. Its length is about 3 cm, consists of 6-8 half rings. The left main bronchus is longer (4-5 cm) and narrower, consisting of 7-12 half rings. The main bronchi enter the gate of the corresponding lung. The main bronchi are the bronchi of the first order. From them depart bronchi of the 2nd order - lobar (3 in the right lung and 2 in the left), which give rise to segmental bronchi (3 orders), and the latter branch dichotomously. In the segmental bronchi there are no cartilaginous half-rings; the cartilage breaks up into separate plates. The segments are formed by pulmonary lobules (up to 80 pieces in 1 segment), which include the lobular bronchus (8th order). In small bronchi (bronchioles) with a diameter of 1-2 mm, cartilaginous plates and glands gradually disappear. Intralobular bronchioles break up into 18-20 terminal bronchioles with a diameter of about 0.5 mm. In the ciliated epithelium of the terminal bronchioles there are individual secretory cells (Clark), which produce enzymes that break down surfactant. These cells are also the source of restoration of the epithelium of the terminal bronchioles. All bronchi, starting from the main bronchi and including the terminal bronchioles, make up the bronchial tree, which serves to conduct a stream of air during inhalation and exhalation; respiratory gas exchange between air and blood does not occur in them.

65. Lungs: boundaries, structure, blood supply, innervation, regional lymph nodes.

The branching of the terminal bronchiole constitutes the structural unit of the lung, the acinus. The terminal bronchioles give rise to 2-8 respiratory (respiratory) bronchioles, and pulmonary (alveolar) vesicles already appear on their walls. Alveolar ducts extend radially from each respiratory bronchiole, blindly ending in alveolar sacs (alveoli). In the walls of the alveolar ducts and alveoli, the epithelium becomes single-layer flat. In the cells of the alveolar epithelium, a factor is formed that reduces the surface tension of the alveoli - surfactant. This substance consists of phospholipids and lipoproteins. Surfactant prevents the lungs from collapsing during exhalation, and the surface tension of the alveolar walls prevents excessive stretching of the lungs during inhalation. During forced inhalation, overstretching of the pulmonary alveoli is also prevented by the elastic structures of the lungs. The alveoli are surrounded by a dense network of capillaries, where gas exchange occurs. Respiratory bronchioles, alveolar ducts and sacs make up the alveolar tree, or respiratory parenchyma of the lungs. Person has 2 lungs - left and right. These are quite voluminous organs, occupying almost the entire volume of the chest, with the exception of its middle part. The lungs are shaped like a cone. The lower expanded part - the base - is adjacent to the diaphragm and is called the diaphragmatic surface. Corresponding to the dome of the diaphragm, there is a depression at the base of the lung. The narrowed, rounded upper part - the apex of the lung - extends through the upper opening of the chest into the neck area. In front it is located 3 cm above the 1st rib, in the back its level corresponds to the neck of the 1st rib. On the lung, in addition to the diaphragmatic surface, there is an external convex surface - the costal surface. On this surface of the lung there are imprints of the ribs. The medial surfaces face the mediastinum and are called mediastinal. In the central part of the mediastinal surface of the lung its gates are located. The gates of each lung include the primary (main) bronchus, a branch of the pulmonary artery that carries venous blood to the lung, and a small bronchial artery (a branch of the thoracic aorta), which carries arterial blood to nourish the lung. In addition, the vessels include nerves that innervate the lungs. Two pulmonary veins emerge from the gates of each lung, which carry arterial blood and lymphatic vessels to the heart. The bifurcation of the trachea, all the structural formations passing through the hilum of the lungs, and the lymph nodes together form the root of the lung. At the site of the transition of the costal surface of the lung to the diaphragmatic surface, a sharp lower edge is formed. Between the costal and mediastinal surfaces there is a sharp edge in front, and a blunt, rounded edge in the back. The lung has deep grooves dividing it into lobes. The right lung has two grooves that divide it into three lobes: upper, middle and lower; on the left - one, dividing the lung into two lobes: upper and lower. According to the nature of the branching of the bronchi and vessels in each lobe, segments are distinguished. In the right lung, there are 3 segments in the upper lobe, 2 segments in the middle lobe, and 5-6 segments in the lower lobe. In the left lung there are 4 segments in the upper lobe, 5-6 segments in the lower lobe. Thus, in the right lung there are 10-11, in the left there are 9-10 segments. The left lung is narrower, but longer than the right, the right lung is wider, but shorter than the left, which corresponds to the higher position of the right dome of the diaphragm due to the liver located in the right hypochondrium.

Blood circulation in the lungs has its own characteristics. Due to the function of gas exchange, the lungs receive not only arterial but also venous blood. Venous blood flows through the branches of the pulmonary arteries, each of which enters the gates of the lung and divides to the capillaries, where gas exchange occurs between the blood and the air of the alveoli: oxygen enters the blood, and from it carbon dioxide enters the alveoli. Pulmonary veins are formed from capillaries, carrying arterial blood to the heart. Arterial blood enters the lungs through the bronchial arteries (from the aorta, posterior intercostal and subclavian arteries). They nourish the wall of the bronchi and lung tissue. From the capillary network, which is formed by the branching of these arteries, bronchial veins are collected, flowing into the azygos and semi-gypsy veins, partly into the pulmonary veins from small bronchioles. Thus, the pulmonary and bronchial vein systems anastomose with each other.

Upper sections respiratory system are supplied with blood by the branches of the external carotid artery (facial, superior thyroid artery, lingual). The nerves of the lungs come from the pulmonary plexus, formed by the branches of the vagus nerves and sympathetic trunks.