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The number of segments in the lungs is. Lung segments: diagram

Radiography is the main method used to diagnose diseases of the respiratory system, and in particular the lungs. This is due to the fact that the lungs are an organ that is located inside chest cavity, and is not available for examination by other methods. However, many diseases cause changes lung tissue, and doctors need to be able to image lung tissue to accurate diagnosis. That's why X-ray found wide application in pulmonology.

Features of the structure of the lungs

The lungs themselves are organs that ensure gas exchange between the blood and environment. The grooves divide the lungs into several lobes. The right lung consists of three, and the left lung consists of two lobes. The shares, in turn, consist of segments. They are truncated cones, the apex of which is directed towards the pulmonary roots. The latter are depressions on both lungs from the mediastinum, through which the pulmonary arteries enter the lungs and the pulmonary veins exit. Of these, each segment includes a branch of the pulmonary arteries and segmental bronchi, into which the two main bronchi are divided.

Pulmonary arteries- branches of the pulmonary trunk extending from the right ventricle

They occupy a central position in the segment, and veins pass between them, inside connective tissue partitions. The number of segments in the lobes of the lungs varies. There are 10 of them on the right:

  • Upper lobe – 3 segments.
  • The average share is 2 segments.
  • Lower lobe – 5 segments.

On the left, both lobes have 4 segments, 8 in total.

Upper Lobe - upper lobe; Middle Lobe - middle beat; Lower Lobe - lower lobe

What are segments?

Inside, the segment consists of lobules, which measure approximately 20 by 15 millimeters, and have their bases facing the outside of the segment. The segmental bronchus is divided into terminal bronchioles, and enters each of the numerous apices. The lobules themselves consist of the main functional unit lungs - acini. It is they who ensure gas exchange between the blood that flows through their capillaries and the air in their cavity.

On an x-ray, the doctor can see the lobes and segments. For easier analysis of the images, the image of the lungs is divided into three conventional parts, drawing horizontal boundaries.

Conventional division of the lungs into three zones

Topography of a normal lung

Topographically, the lungs are distinguished by apical zones that are located above the shadow of the clavicles. Below the collarbone, the upper part of the lungs begins, the lower border of which is the anterior segments of the second ribs. From the second to fourth costal segments there are the middle sections, and down from them there are the lower sections. Thus, there are three landmarks on the radiograph - the collarbones, and the anterior ends of the second and fourth pairs of ribs.

If you draw a vertical line through the point where the clavicle intersects with the outer contour of the ribs and the middle of the clavicle, then the pulmonary field will be divided into inner, outer and medial zones.

Since the segments are layered on top of each other, their detailed study is carried out in a lateral projection image.

The right lung is represented by ten segments. The 1st segment of the apex is located in the dome. The posterior C2 of the upper lobe begins from its posterior surface, and C3 begins from the anterior outer surface.

C4 of the middle lobe is located outside, located between the horizontal fissure and the lower parts of the oblique. Ahead is C5.

If you draw an imaginary line from the accessory interlobar fissure back, it will become the lower border of the 6th segment of the lower lobe. Segments C7 to C10 are located at its base. The most medial is the 7th, it overlaps the 8th and 9th, lateral. At the rear is C10.

On the left their location is slightly different. C1-C3 are united into a large posterior apical segment. Below, in place of the middle lobe, there is a lingular segment, which is divided into C4 and C5.

X-ray anatomy chest(lung segments are indicated by numbers)

Indications for the study

A plain radiograph of the chest organs is a routine examination method. Moreover, fluorography, which is a modification of this study, should be carried out by everyone healthy people about once a year.

When a patient is admitted to the hospital, doctors in most cases order an x-ray, since it is imperative to make sure that there are no pathological changes, which may be signs of the initial stages of the disease. After all, some pathologies can be identified using this method even before a person has complaints.

In order for an x-ray to be prescribed, the following symptoms must be present:

  • Cough.
  • Complaints of shortness of breath.
  • Complaints about lack of air.
  • Whistles when breathing.
  • Wheezing when breathing.
  • Change breathing movements chest.
  • Chest pain, especially when breathing.
  • Swelling in the legs.
  • Mantoux reaction different from normal.

Lung image analysis

Thus, X-rays can be analyzed in stages, which allows doctors not to miss changes that are subtle at first glance. However, it must be remembered that this is a conditional division, and the radiological zones are not equivalent to the pulmonary segments. First you need to evaluate their symmetry and the presence of obvious defects. They can be represented by elements of darkening or clearing, as well as changes in the shape and size of the lungs, as well as a violation of their contours.

Since the lungs are filled with air, which passes well x-rays, then on x-ray they look like light tissue with high transparency.

Their structure is called the pulmonary pattern. It is formed by small branches of the pulmonary arteries and veins, as well as small bronchi.

Since from the roots and to the periphery the vessels and bronchi are divided into smaller branches, which are less visible on x-rays, the intensity of the pattern from the center to the periphery decreases. It becomes paler and almost indistinguishable at the outer edges of the lungs. It also becomes depleted in the upper sections, becoming thickest towards the bottom.

Pathology detected on images

Almost all diseases that can occur in the lungs change the density of their tissue and its airiness. On an x-ray, this appears as areas of darkening or clearing. For example, segmental pneumonia leads to tissue infiltration by leukocytes and macrophages, dilation of blood vessels, and, as a result, edema. As a result, the area becomes denser, transmits X-rays less well, and a darkened zone is visible in the image.

The oval indicates the darkening area

You need to carefully examine the root area and pulmonary pattern. Their strengthening indicates either early stages inflammatory process, or about an obstacle to the outflow of blood, for example, thrombosis, edema in heart failure. Knowledge of the segmental structure can help in differential diagnosis. Thus, tuberculosis most often affects the apical segments, since they have poor oxygenation, which allows mycobacteria to easily grow and multiply. But pneumonia often develops in the lower and middle sections.

Lung segments are areas of tissue within a lobe that have a bronchus, which is supplied with blood by one of the branches of the pulmonary artery. These elements are in the center. The veins that collect blood from them lie in the partitions that separate the areas. The base with the visceral pleura is adjacent to the surface, and the apex to the root of the lung. This division of the organ helps in determining the location of the focus of pathology in the parenchyma.

Existing classification

The most famous classification was adopted in London in 1949 and confirmed and expanded to International Congress 1955. According to it, in the right lung it is customary to distinguish ten bronchopulmonary segments:

IN upper lobe There are three (S1–3):

  • apical;
  • rear;
  • front.

In the middle part there are two (S4–5):

  • lateral;
  • medial.

Five are found in the lower part (S6–10):

  • upper;
  • cardiac/mediabasal;
  • anterobasal;
  • laterobasal;
  • posterobasal.

On the other side of the body, ten bronchopulmonary segments are also found:

  • apical;
  • rear;
  • front;
  • upper reed;
  • lower reed.

In the part below, there are also five (S6–10):

  • upper;
  • mediabasal/inconsistent;
  • anterobasal;
  • lateralobasal or laterobasal;
  • posterobasal/peripheral.

The middle lobe is not defined on the left side of the body. This classification of lung segments fully reflects the existing anatomical and physiological picture. It is used by practitioners around the world.

Features of the structure of the right lung

On the right, the organ is divided into three lobes according to their location.

S1- apical, the front part is located behind the II rib, then to the end of the scapula through pulmonary apex. Has four borders: two with outside and two edge ones (with S2 and S3). Includes part respiratory tract up to 2 centimeters in length, in most cases they are shared with S2.

S2- posterior, passes behind from the angle of the scapula from above to the middle. Localized dorsal to the apical one, it contains five boundaries: with S1 and S6 on the inside, with S1, S3 and S6 on the outside. The airways are localized between the segmental vessels. In this case, the vein is connected to that of S3 and flows into the pulmonary vein. The projection of this segment of the lungs is located at the level of the II–IV rib.

S3- anterior, occupies the area between the II and IV ribs. It has five edges: with S1 and S5 on the inside and with S1, S2, S4, S5 on the outside. The artery is a continuation of the upper branch of the pulmonary, and the vein flows into it, lying behind the bronchus.

Average share

Localized between the IV and VI ribs on the anterior side.

S4- lateral, located in front of armpit. The projection is a narrow strip located above the groove between the lobes. The lateral segment contains five borders: with a medial and anterior one from the inside, three edges with a medial one on the costal side. The tubular branches of the trachea extend back, lying deep, along with the vessels.

S5- medial, located behind the sternum. It is projected on both the external and medial sides. This segment of the lung has four edges, touching the anterior and last medially, from the midpoint of the horizontal groove in front to the extreme point of the oblique, with the anterior along the horizontal groove on the outer part. The artery belongs to a branch of the inferior pulmonary, sometimes coinciding with that in the lateral segment. The bronchus is located between the vessels. The boundaries of the area are located within the IV–VI rib along the segment from the middle of the armpit.

Localized from the center of the scapula to the diaphragmatic dome.

S6- upper, located from the center of the scapula to its lower angle (from III to VII ribs). It has two edges: with S2 (along the oblique groove) and with S8. This segment of the lung is supplied with blood through the artery, which is a continuation of the inferior pulmonary artery, which lies above the vein and tubular branches of the trachea.

S7- cardiac/mediabasal, localized under the pulmonary hilum with inside, between the right atrium and the branch of the vena cava. Contains three edges: S2, S3 and S4, and is detected in only a third of people. The artery is a continuation of the inferior pulmonary artery. The bronchus departs from the lower lobe and is considered its highest branch. The vein is localized under it and enters the right pulmonary.

S8- anterior basal segment, localized between the VI–VIII rib along the segment from the middle of the armpit. It has three edges: with the laterobasal (along the oblique groove separating the sections, and in the projection of the pulmonary ligament) and with the upper segments. The vein flows into the inferior cava, and the bronchus is considered a branch of the inferior lobe. The vein is localized below the lung ligament, and the bronchus and artery are in the oblique groove separating the sections, under the visceral part of the pleura.

S9- laterobasal - located between the VII and IX ribs posteriorly along the segment from the armpit. Has three edges: S7, S8 and S10. The bronchus and artery lie in the oblique groove, the vein is located under the pulmonary ligament.

S10- posterior basal segment, adjacent to the spine. Localized between the VII and X rib. Equipped with two borders: S6 and S9. The vessels, together with the bronchus, lie in the oblique groove.

On the left side, the organ is divided into two parts according to their location.

Upper lobe

S1- apical, similar in shape to that in the right organ. The vessels and bronchus are located above the hilum.

S2- posterior, reaches the V accessory bone of the chest. It is often combined with the apical bronchus due to the common bronchus.

S3- anterior, located between the II and IV ribs, has a border with the upper lingular segment.

S4- upper lingular segment, localized on the medial and costal side in the region of the III–V rib along the anterior surface of the chest and along the mid-axillary line from the IV to VI rib.

S5- lower lingual segment, located between the V accessory bone of the chest and the diaphragm. The lower border runs along the interlobar groove. Anteriorly, between the two reed segments, the center of the cardiac shadow is located.

S6- upper, localization coincides with that on the right.

S7- mediabasal, similar to symmetrical.

S8- anterior basal, located mirror image to the right one of the same name.

S9- laterobasal, localization coincides with the other side.

S10- posterior basal, coincides in location with that in the other lung.

Visibility on X-ray

On an x-ray, normal lung parenchyma is visible as a homogeneous tissue, although in life this is not the case. The presence of extraneous lightening or darkening will indicate the presence of pathology. Using the X-ray method, it is not difficult to determine lung injuries, the presence of fluid or air in the pleural cavity, as well as neoplasms.

Cleared areas appear as dark spots on an x-ray due to the way the image is developed. Their appearance means increased airiness of the lungs with emphysema, as well as tuberculous cavities and abscesses.

Darkening zones are visible as white spots or general darkening in the presence of fluid or blood in the lung cavity, as well as when large quantities small foci of infection. This is what dense neoplasms, places of inflammation look like, foreign bodies in the lung.

Lung segments and lobes, as well as medium and small bronchi, alveoli are not visible on the x-ray. Computed tomography is used to identify the pathologies of these formations.

Applications of computed tomography

Computed tomography (CT) is one of the most accurate and modern methods research for any pathological process. The procedure allows you to view each lobe and segment of the lung for the presence of an inflammatory process, as well as evaluate its nature. When conducting research you can see:

  • segmental structure and possible damage;
  • change of share plots;
  • airways of any size;
  • intersegmental partitions;
  • impaired blood circulation in the vessels of the parenchyma;
  • changes in lymph nodes or their displacement.

Computed tomography allows you to measure the thickness of the airways to determine the presence of changes in them, the size of the lymph nodes and view each section of tissue. The images are interpreted by the doctor who gives the patient a final diagnosis.

Like all the most important life support systems of the human body, the respiratory system is represented by paired, that is, doubled to increase reliability, organs. These organs are called lungs. They are located inside the rib cage, formed by the ribs and spine, which protects the lungs from external damage.

According to the position of the organs in the chest cavity, the right and left lungs are distinguished. Both organs have the same structural structure, which is due to the performance of a single function. The main task The lungs are responsible for gas exchange. In them, the blood absorbs oxygen from the air, which is necessary for the implementation of all biochemical processes in the body, and the release of carbon dioxide from the blood, known to everyone as carbon dioxide.

The easiest way to understand the principle is lung structure, if you imagine a huge bunch of grapes with tiny grapes. The main breathing tube (main) is divided geometrically into smaller ones. The thinnest ones, called terminal ones, reach a diameter of 0.5 millimeters. With further division, pulmonary vesicles () appear around the bronchioles, in which the process of gas exchange occurs. The main tissue of the lung is formed from a huge (hundreds of millions) number of these pulmonary vesicles.

The right and left lungs are functionally united and perform one task in our body. Therefore, the structural structure of their tissue is completely identical. But the coincidence of structure and unity of function does not mean complete identity of these organs. In addition to similarities, there are also differences.

The main difference between these paired organs is explained by their location in the chest cavity, where the heart is also located. The asymmetrical position of the heart in the chest led to differences in the size and external shape of the right and left lungs.

Right lung

Right lung:
1 — apex of the lung;
2 - upper lobe;
3 - main right bronchus;
4 - costal surface;
5 - mediastinal (mediastinal) part;
6 - cardiac indentation;
7 - vertebral part;
8 - oblique slot;
9 - middle share;

By volume right lung exceeds the left one by about 10%. Moreover, in terms of its linear dimensions, it is somewhat smaller in height and wider than the left lung. There are two reasons here. Firstly, the heart in the chest cavity is more shifted to the left. Therefore, the space to the right of the heart in the chest is correspondingly larger. Secondly, the person on the right has abdominal cavity the liver is located, which seems to press the right half of the chest cavity from below, slightly reducing its height.

Both of our lungs are divided into their structural parts, which are called lobes. The basis of division, despite the commonly designated anatomical landmarks, is the principle functional structure. A lobe is the part of the lung that is supplied with air through the second-order bronchus. That is, through those bronchi that separate directly from the main bronchus, which carries air to the entire lung from the trachea.

Main bronchus right lung is divided into three branches. Accordingly, three parts of the lung are distinguished, which are designated as the upper, middle and lower lobe of the right lung. All lobes of the right lung are functionally equivalent. Each of them contains all the necessary structural elements for gas exchange. But there are differences between them. The upper lobe of the right lung differs from the middle and lower lobe not only in its topographic location (located in the upper part of the lung), but also in volume. The smallest size is the middle lobe of the right lung, the largest is the lower lobe.

Left lung

Left lung:
1 - root of the lung;
2 - costal surface;
3 - mediastinal (mediastinal) part;
4 - left main bronchus;
5 - upper lobe;
6 - cardiac indentation;
7 - oblique slot;
8 - cardiac notch of the left lung;
9 - lower lobe;
10 - diaphragmatic surface

The existing differences from the right lung boil down to the difference in size and external shape. The left lung is somewhat narrower and longer than the right. In addition, the main bronchus of the left lung is divided into only two branches. For this reason, not three, but two functionally equivalent parts are distinguished: the upper lobe of the left lung and the lower lobe.

The volume of the upper and lower lobes of the left lung differs slightly.

The main bronchi, each entering its own lung, also have noticeable differences. The diameter of the right main bronchial trunk is increased in comparison with the left main bronchus. The reason was that the right lung is larger than the left. They also have different lengths. The left bronchus is almost twice as long as the right. The direction of the right bronchus is almost vertical; it is, as it were, a continuation of the course of the trachea.

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Segmental structure of the lungs (human anatomy)

The lungs secrete 10 bronchopulmonary segments, which have their own segmental bronchus, a branch of the pulmonary artery, a bronchial artery and vein, nerves and lymphatic vessels. The segments are separated from each other by layers of connective tissue in which intersegmental pulmonary veins(Fig. 127)


Rice. 127. Segmental structure of the lungs. a, b - segments of the right lung, external and internal views; c, d - segments of the left lung, external and internal views. 1 - apical segment; 2 - posterior segment; 3 - anterior segment; 4 - lateral segment (right lung) and upper lingular segment (left lung); 5 - medial segment (right lung) and lower lingular segment (left lung); 6 - apical segment of the lower lobe; 7 - basal medial segment; 8 - basal anterior segment; 9 - basal lateral segment; 10 - basal posterior segment

Segments of the right lung

Left lung segments

The segmental bronchi have similar names.

Topography of the lungs . The lungs are located in pleural cavities(see section Urogenital system, this edition) of the chest. The projection of the lungs onto the ribs constitutes the boundaries of the lungs, which in a living person are determined by tapping (percussion) and x-ray. There are borders of the apex of the lungs, anterior, posterior and inferior borders.

The apices of the lungs are 3-4 cm above the collarbone. The anterior border of the right lung goes from the apex to the II rib along the linea parasternalis and further along it to the VI rib, where it passes into the lower border. The anterior border of the left lung extends to the III rib, as well as the right one, and in the IV intercostal space it deviates horizontally to the left to the linea medioclavicularis, from where it follows down to the VI rib, where the lower border begins.

The lower border of the right lung runs in a gentle line in front from the cartilage of the VI rib back and down to the spinous process of the XI thoracic vertebra, crossing along the linea medioclavicularis the upper edge of the VII rib, along the linea axillaris media - the upper edge of the VIII rib, along the linea axillaris posterior - the IX rib, along linea scapularis - the upper edge of the X rib and along the linea paravertebralis - the XI rib. The lower border of the left lung is 1 - 1.5 cm below the right.

The costal surface of the lungs is in contact throughout the entire length with the chest wall, the diaphragmatic surface is adjacent to the diaphragm, the medial surface is adjacent to the mediastinal pleura and through it to the mediastinal organs (right - to the esophagus, azygos and superior vena cava, right subclavian artery, heart, left - to the left subclavian artery, thoracic aorta, heart).

The topography of the root elements of the right and left lungs is not the same. At the root of the right lung, the right main bronchus is located above, below is the pulmonary artery, in front and below which are the pulmonary veins. At the root of the left lung above lies the pulmonary artery, behind and below which the main bronchus passes, and below and anterior to the bronchus are the pulmonary veins.

X-ray anatomy of the lungs (human anatomy)

On x-ray In the chest, the lungs appear as light lung fields intersected by oblique, cord-like shadows. The intense shadow coincides with the root of the lung.

Vessels and nerves of the lungs (human anatomy)

Lung vessels belong to two systems: 1) vessels small circle related to gas exchange and transport of gases absorbed by the blood; 2) vessels great circle blood circulation that nourishes the lung tissue.

The pulmonary arteries, carrying venous blood from the right ventricle, branch in the lungs into lobar and segmental arteries and then according to the division of the bronchial tree. The resulting capillary network entwines the alveoli, which ensures the diffusion of gases into and out of the blood. Veins formed from capillaries carry arterial blood through the pulmonary veins to the left atrium.

A segment is a cone-shaped section of the lung lobe, whose base faces the surface of the lung and its apex faces the root, ventilated by a third-order bronchus, and consisting of pulmonary lobes. The segments are separated from each other by connective tissue. In the center of the segment there are a segmental bronchus and an artery, and in the connective tissue septum there is a segmental vein.

According to the International Anatomical Nomenclature, the right and left lungs are distinguished by 10 segments. The names of the segments reflect their topography and correspond to the names of the segmental bronchi.

Right lung.

IN upper lobe the right lung has 3 segments:

– apical segment ,segmentum apicale, occupies the superomedial portion of the upper lobe, enters top hole chest and fills the dome of the pleura;

– posterior segment , segmentum posterius, its base is directed outward and backward, bordering there with the II-IV ribs; its apex faces the upper lobe bronchus;

– anterior segment , segmentum anterius, its base is adjacent to the anterior wall of the chest between the cartilages of the 1st and 4th ribs, as well as to the right atrium and the superior vena cava.

Average share has 2 segments:

– lateral segment, segmentum laterale, its base is directed forward and outward, and its apex is directed upward and medially;

– medial segment, segmentum mediale, touches the front chest wall near the sternum, between the IV-VI ribs; it is adjacent to the heart and diaphragm.

Rice. 1.37. Lungs.

1 – larynx, larynx; 2 – trachea, trachea; 3 – apex of the lung, apex pulmonis; 4 – costal surface, facies costalis; 5 – bifurcation of the trachea, bifurcatio tracheae; 6 – upper lobe of the lung, lobus pulmonis superior; 7 – horizontal fissure of the right lung, fissura horizontalis pulmonis dextri; 8 – oblique fissure, fissura obliqua; 9 – cardiac notch of the left lung, incisura cardiaca pulmonis sinistri; 10 – middle lobe of the lung, lobus medius pulmonis; 11 – lower lobe of the lung, lobus inferior pulmonis; 12 – diaphragmatic surface, facies diaphragmatica; 13 – base of the lung, basis pulmonis.

IN lower lobe There are 5 segments:

– apical segment, segmentumapicale (superius), occupies the wedge-shaped apex of the lower lobe and is located in the paravertebral region;



– medial basal segment, segmentum basale mediale (cardiacum), The base occupies the mediastinal and partly the diaphragmatic surface of the lower lobe. It is adjacent to the right atrium and the inferior vena cava;

– anterior basal segment , segmentum basale anterius, is located on the diaphragmatic surface of the lower lobe, and the large lateral side is adjacent to the chest wall in the axillary region between the VI-VIII ribs;

– lateral basal segment , segmentum basale laterale, wedged between other segments of the lower lobe so that its base is in contact with the diaphragm, and its side is adjacent to the chest wall in the axillary region, between the VII and IX ribs;

– posterior basal segment , segmentum basale posterius, located paravertebrally; it lies posterior to all other segments of the lower lobe, penetrating deeply into the costophrenic sinus of the pleura. Sometimes it is separated from this segment .

Left lung.

It also distinguishes 10 segments.

The upper lobe of the left lung has 5 segments:

– apical-posterior segment , segmentum apicoposterius, corresponds in shape and position apical segment ,segmentum apicale, and posterior segment , segmentum posterius, upper lobe of the right lung. The base of the segment is in contact with the posterior sections of the III-V ribs. Medially, the segment is adjacent to the aortic arch and subclavian artery; may be in the form of two segments;

– anterior segment , segmentum anterius, is the largest. It occupies a significant part of the costal surface of the upper lobe, between the I-IV ribs, as well as part of the mediastinal surface, where it comes into contact with truncus pulmonalis ;

– upper lingual segment, segmentumlingulare superius, is a section of the upper lobe between ribs III-V in front and ribs IV-VI in the axillary region;

– lower lingual segment, segmentum lingulare inferius, is located below the upper one, but almost does not come into contact with the diaphragm.

Both lingular segments correspond to the middle lobe of the right lung; they come into contact with the left ventricle of the heart, penetrating between the pericardium and the chest wall into the costomediastinal sinus of the pleura.

In the lower lobe of the left lung there are 5 segments, which are symmetrical to the segments of the lower lobe of the right lung:

– apical segment, segmentum apicale (superius), occupies a paravertebral position;

– medial basal segment, segmentum basale mediale, in 83% of cases it has a bronchus that begins with a common trunk with the bronchus of the next segment, segmentum basale anterius. The latter is separated from the lingular segments of the upper lobe, fissura obliqua, and participates in the formation of the costal, diaphragmatic and mediastinal surfaces of the lung;

– lateral basal segment , segmentum basale laterale, occupies the costal surface of the lower lobe in the axillary region at the level of the XII-X ribs;

– posterior basal segment, segmentum basale posterius, is a large area of ​​the lower lobe of the left lung located posterior to other segments; it comes into contact with the VII-X ribs, the diaphragm, the descending aorta and the esophagus;

– segmentum subapicale (subsuperius) this one is not always available.

Pulmonary lobules.

The lung segments consist of fromsecondary pulmonary lobules, lobuli pulmones secundarii, in each of which includes a lobular bronchus (4-6 orders). This is a pyramidal-shaped area of ​​pulmonary parenchyma up to 1.0-1.5 cm in diameter. Secondary lobules are located on the periphery of the segment in a layer up to 4 cm thick and are separated from each other by connective tissue septa, which contain veins and lymphocapillaries. Dust (coal) is deposited in these partitions, making them clearly visible. In both lungs there are up to 1 thousand secondary lobes.

5) Histological structure. alveolar tree, arbor alveolaris.

Pulmonary parenchyma by functional and structural features is divided into two sections: conductive - this is the intrapulmonary part of the bronchial tree (mentioned above) and respiratory, which carries out gas exchange between the venous blood flowing to the lungs through the pulmonary circulation and the air in the alveoli.

The respiratory section of the lung consists of acini, acinus , – structural and functional units of the lung, each of which is a derivative of one terminal bronchiole. The terminal bronchiole divides into two respiratory bronchioles, bronchioli respiratorii , on the walls of which appear alveoli, alveoli pulmones,- cup-shaped structures lined from the inside with flat cells, alveolocytes. Elastic fibers are present in the walls of the alveoli. At the beginning, along the respiratory bronchiole, there are only a few alveoli, but then their number increases. Between the alveoli are located epithelial cells. In total, there are 3-4 generations of dichotomous division of respiratory bronchioles. Respiratory bronchioles, expanding, give rise to alveolar ducts, ductuli alveolares (from 3 to 17), each of which ends blindly alveolar sacs, sacculi alveolares. The walls of the alveolar ducts and sacs consist only of alveoli, braided with a dense network blood capillaries. Inner surface alveoli, facing the alveolar air, is covered with a film of surfactant - surfactant, which equalizes surface tension in the alveoli and prevents their walls from gluing - atelectasis. In the lungs of an adult there are about 300 million alveoli, through the walls of which gases diffuse.

Thus, respiratory bronchioles of several orders of branching, extending from one terminal bronchiole, alveolar ducts, alveolar sacs and alveoli form pulmonary acinus, acinus pulmonis . The respiratory parenchyma of the lungs has several hundred thousand acini and is called the alveolar tree.

The terminal respiratory bronchiole and the alveolar ducts and sacs extending from it form primary lobule lobulus pulmonis primarius . There are about 16 of them in each acini.


6) Age characteristics. The lungs of a newborn have an irregular cone shape; upper lobes relatively small in size; The middle lobe of the right lung is equal in size to the upper lobe, and the lower lobe is relatively large. In the 2nd year of a child’s life, the size of the lobes of the lung relative to each other becomes the same as in an adult. The weight of the newborn’s lungs is 57 g (from 39 to 70 g), volume 67 cm³. Age-related involution begins after 50 years. The boundaries of the lungs also change with age.

7) Developmental anomalies. Pulmonary agenesis – absence of one or both lungs. If both lungs are missing, the fetus is not viable. Lung hypogenesis – underdevelopment of the lungs, often accompanied by respiratory failure. Anomalies of the terminal parts of the bronchial tree – bronchiectasis – irregular saccular dilatations of terminal bronchioles. Reverse position organs of the chest cavity, while the right lung contains only two lobes, and the left lung consists of three lobes. The reverse position can be only thoracic, only abdominal and total.

8) Diagnostics. An x-ray examination of the chest clearly shows two light “pulmonary fields”, which are used to judge the lungs, since due to the presence of air in them, they easily transmit x-rays. Both pulmonary fields are separated from each other by an intense central shadow formed by the sternum, spinal column, heart and large vessels. This shadow constitutes the medial border of the lung fields; the upper and lateral borders are formed by ribs. Below is the diaphragm. Upper part The pulmonary field is intersected by the clavicle, which separates the supraclavicular region from the subclavian region. Below the clavicle, the anterior and posterior parts of the ribs intersecting each other are layered onto the pulmonary field.

X-ray method The study allows you to see changes in the relationships of the chest organs that occur during breathing. When you inhale, the diaphragm lowers, its domes flatten, the center moves slightly downwards - the ribs rise, the intercostal spaces become wider. Lung fields become lighter, the pulmonary pattern becomes clearer. The pleural sinuses “clear up” and become noticeable. The position of the heart approaches vertical, and it takes on a shape close to triangular. When you exhale, the opposite relationship occurs. Using X-ray kymography, you can also study the work of the diaphragm during breathing, singing, speech, etc.

With layer-by-layer radiography (tomography), the structure of the lung is revealed better than with ordinary radiography or fluoroscopy. However, even on tomograms it is not possible to differentiate individual structural lung formation. This is made possible thanks to special method X-ray examination (electroradiography). On the radiographs obtained with the help of the latter, not only tubular lung systems, (bronchi and blood vessels), but also the connective tissue frame of the lung. As a result, it is possible to study the structure of the parenchyma of the entire lung in a living person.

Pleura.

In the chest cavity there are three completely separate serous sacs - one for each lung and one, middle, for the heart.

Serosa the lung is called the pleura, p1eura. It consists of two sheets:

visceral pleura pleura visceralis ;

pleura parietal, parietal pleura parietalis .