What is the lingular segment of the left lung? X-ray examination of lung segments in the practice of a pulmonologist. Topographic location of lung segments on a radiograph

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 the upper opening of the 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, comes into contact with the anterior 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.

The pulmonary parenchyma, according to its 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. Epithelial cells are located between the alveoli. 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, intertwined with a dense network of blood capillaries. The inner surface of the 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; the upper lobes are 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 of the thoracic cavity organs, 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 “lung 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. The upper part of the pulmonary field is crossed 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.

The X-ray method of research 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. The pulmonary 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 formations of the lung. This becomes possible thanks to a special method of x-ray examination (electroradiography). The radiographs obtained using the latter show not only the tubular systems of the lung (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.

The serous membrane of the lung is called the pleura, p1eura. It consists of two sheets:

visceral pleura pleura visceralis ;

pleura parietal, parietal pleura parietalis .

It is possible to detect a tumor in the lungs and determine what it may be with a detailed examination. People of different ages are susceptible to this disease. Formations arise due to disruption of the process of cell differentiation, which can be caused by internal and external factors.

Neoplasms in the lungs are a large group of different formations in the lung area, which have a characteristic structure, location and nature of origin.

Neoplasms in the lungs can be benign or malignant.

Benign tumors have different genesis, structure, location and different clinical manifestations. Benign tumors are less common than malignant tumors and make up about 10% of the total. They tend to develop slowly and do not destroy tissue, since they are not characterized by infiltrating growth. Some benign tumors tend to transform into malignant ones.

Depending on the location there are:

1. Central - tumors from the main, segmental, lobar bronchi. They can grow inside the bronchus and surrounding lung tissue.
2. Peripheral - tumors from surrounding tissues and walls of small bronchi. They grow superficially or intrapulmonarily.

Types of benign tumors

There are the following benign lung tumors:

Briefly about malignant tumors

Lung cancer (bronchogenic carcinoma) is a tumor consisting of epithelial tissue. The disease tends to metastasize to other organs. It can be located in the periphery, the main bronchi, or grow into the lumen of the bronchus or organ tissue.

Malignant neoplasms include:

1. Lung cancer has the following types: epidermoid, adenocarcinoma, small cell tumor.
2. Lymphoma is a tumor that affects the lower respiratory tract. It may occur primarily in the lungs or as a result of metastases.
3. Sarcoma is a malignant formation consisting of connective tissue. Symptoms are similar to those of cancer, but develop more quickly.
4. Pleural cancer is a tumor that develops in the epithelial tissue of the pleura. It can occur primarily, and as a result of metastases from other organs.

Risk factors

The causes of malignant and benign tumors are largely similar. Factors that provoke tissue proliferation:

• Smoking active and passive. 90% of men and 70% of women who have been diagnosed with malignant tumors in the lungs are smokers.
• Contact with hazardous chemicals and radioactive substances due to professional activities and environmental pollution in the area of ​​residence. Such substances include radon, asbestos, vinyl chloride, formaldehyde, chromium, arsenic, and radioactive dust.
• Chronic respiratory diseases. The development of benign tumors is associated with the following diseases: chronic bronchitis, chronic obstructive pulmonary disease, pneumonia, tuberculosis. The risk of malignant neoplasms increases if there is a history of chronic tuberculosis and fibrosis.

The peculiarity is that benign formations can be caused not by external factors, but by gene mutations and genetic predisposition. Malignancy and transformation of the tumor into malignant also often occur.

Any lung formations can be caused by viruses. Cell division can be caused by cytomegalovirus, human papillomavirus, multifocal leukoencephalopathy, simian virus SV-40, and human polyomavirus.

Symptoms of a tumor in the lung

Benign lung formations have various signs that depend on the location of the tumor, its size, existing complications, hormonal activity, the direction of tumor growth, and impaired bronchial obstruction.

Complications include:

• abscess pneumonia;
• malignancy;
• bronchiectasis;
• atelectasis;
• bleeding;
• metastases;
• pneumofibrosis;
• compression syndrome.

Bronchial patency has three degrees of impairment:

• 1st degree – partial narrowing of the bronchus.
• 2nd degree – valvular narrowing of the bronchus.
• 3rd degree – occlusion (impaired patency) of the bronchus.

Symptoms of the tumor may not be observed for a long time. The absence of symptoms is most likely with peripheral tumors. Depending on the severity of the symptoms, several stages of the pathology are distinguished.

Stages of formations

Stage 1. It is asymptomatic. At this stage, partial narrowing of the bronchus occurs. Patients may have a cough with a small amount of sputum. Hemoptysis is rare. During examination, the x-ray does not reveal any abnormalities. Tests such as bronchography, bronchoscopy, and computed tomography can show the tumor.

Stage 2. Valve narrowing of the bronchus is observed. At this point, the lumen of the bronchus is practically closed by the formation, but the elasticity of the walls is not impaired. When you inhale, the lumen partially opens, and when you exhale, it closes with the tumor. In the area of ​​the lung that is ventilated by the bronchus, expiratory emphysema develops. As a result of the presence of bloody impurities in the sputum and swelling of the mucous membrane, complete obstruction (impaired patency) of the lung may occur. Inflammatory processes may develop in the lung tissues. The second stage is characterized by a cough with the release of mucous sputum (pus is often present), hemoptysis, shortness of breath, increased fatigue, weakness, chest pain, fever (due to the inflammatory process). The second stage is characterized by alternation of symptoms and their temporary disappearance (with treatment). An X-ray image shows impaired ventilation, the presence of an inflammatory process in a segment, lobe of the lung, or an entire organ.

To be able to make an accurate diagnosis, bronchography, computed tomography, and linear tomography are required.

Stage 3. Complete obstruction of the bronchial tube occurs, suppuration develops, and irreversible changes in lung tissue and their death occur. At this stage, the disease has such manifestations as impaired breathing (shortness of breath, suffocation), general weakness, excessive sweating, chest pain, elevated body temperature, cough with purulent sputum (often with bloody particles). Sometimes pulmonary hemorrhage may occur. During examination, an x-ray may show atelectasis (partial or complete), inflammatory processes with purulent-destructive changes, bronchiectasis, and a space-occupying lesion in the lungs. To clarify the diagnosis, a more detailed study is necessary.

Symptoms

Symptoms of low-quality tumors also vary depending on the size, location of the tumor, the size of the bronchial lumen, the presence of various complications, and metastases. The most common complications include atelectasis and pneumonia.

At the initial stages of development, malignant cavitary formations that arise in the lungs show few signs. The patient may experience the following symptoms:

• general weakness, which intensifies as the disease progresses;
• increased body temperature;
• fast fatiguability;
• general malaise.

Symptoms of the initial stage of neoplasm development are similar to those of pneumonia, acute respiratory viral infections, and bronchitis.

The progression of a malignant formation is accompanied by symptoms such as cough with sputum consisting of mucus and pus, hemoptysis, shortness of breath, and suffocation. When the tumor grows into the vessels, pulmonary hemorrhage occurs.

A peripheral lung mass may not show signs until it invades the pleura or chest wall. After this, the main symptom is pain in the lungs that occurs when inhaling.

In later stages, malignant tumors appear:

• increased constant weakness;
• weight loss;
• cachexia (depletion of the body);
• the occurrence of hemorrhagic pleurisy.

Diagnostics

To detect tumors, the following examination methods are used:

1. Fluorography. A preventive diagnostic method, x-ray diagnostics, which allows you to identify many pathological formations in the lungs. read this article.
2. Plain radiography of the lungs. Allows you to identify spherical formations in the lungs that have a round outline. An x-ray image reveals changes in the parenchyma of the examined lungs on the right, left or both sides.
3. CT scan. Using this diagnostic method, the lung parenchyma, pathological changes in the lungs, and each intrathoracic lymph node are examined. This study is prescribed when differential diagnosis of round formations with metastases, vascular tumors, and peripheral cancer is necessary. Computed tomography allows a more accurate diagnosis to be made than x-ray examination.
4. Bronchoscopy. This method allows you to examine the tumor and perform a biopsy for further cytological examination.
5. Angiopulmonography. It involves performing invasive radiography of blood vessels using a contrast agent to detect vascular tumors of the lung.
6. Magnetic resonance imaging. This diagnostic method is used in severe cases for additional diagnostics.
7. Pleural puncture. Study in the pleural cavity with a peripheral tumor location.
8. Cytological examination of sputum. Helps determine the presence of a primary tumor, as well as the appearance of metastases in the lungs.
9. Thoracoscopy. It is carried out to determine the operability of a malignant tumor.

Fluorography.

Bronchoscopy.

Angiopulmonography.

Magnetic resonance imaging.

Pleural puncture.

Cytological examination of sputum.

Thoracoscopy.

It is believed that benign focal formations of the lungs are no more than 4 cm in size; larger focal changes indicate malignancy.

Treatment

All neoplasms are subject to surgical treatment. Benign tumors must be immediately removed after diagnosis in order to avoid an increase in the area of ​​affected tissue, trauma from surgery, the development of complications, metastases and malignancy. For malignant tumors and benign complications, a lobectomy or bilobectomy may be required to remove a lobe of the lung. With the progression of irreversible processes, a pneumonectomy is performed - removal of the lung and surrounding lymph nodes.

Central cavity formations localized in the lungs are removed by resection of the bronchus without affecting the lung tissue. With such localization, removal can be done endoscopically. To remove tumors with a narrow base, a fenestrated resection of the bronchial wall is performed, and for tumors with a wide base, a circular resection of the bronchus is performed.

For peripheral tumors, surgical treatment methods such as enucleation, marginal or segmental resection are used. For large tumors, lobectomy is used.

Lung formations are removed using thoracoscopy, thoracotomy and videothoracoscopy. During the operation, a biopsy is performed, and the resulting material is sent for histological examination.

For malignant tumors, surgical intervention is not performed in the following cases:

• when it is not possible to completely remove the tumor;
• metastases are located at a distance;
• impaired functioning of the liver, kidneys, heart, lungs;
• The patient's age is more than 75 years.

After removal of the malignant tumor, the patient undergoes chemotherapy or radiation therapy. In many cases, these methods are combined.

Segment S1 (apical or apical) of the right lung. Refers to the upper lobe of the right lung. Topographically projected onto the chest along the anterior surface of the 2nd rib, through the apex of the lung to the spine of the scapula.

Segment S2 (posterior) of the right lung. Refers to the upper lobe of the right lung. Topographically projected onto the chest along the posterior surface paravertebrally from the upper edge of the scapula to its middle.

Segment S3 (anterior) of the right lung. Refers to the upper lobe of the right lung. Topographically, 2 to 4 ribs are projected onto the chest in front.

Segment S4 (lateral) of the right lung. Refers to the middle lobe of the right lung. Topographically projected onto the chest in the anterior axillary region between the 4th and 6th ribs.

Segment S5 (medial) of the right lung. Refers to the middle lobe of the right lung. Topographically projected onto the chest between the 4th and 6th ribs closer to the sternum.

Segment S6 (superior basal) of the right lung. Refers to the lower lobe of the right lung. Topographically projected onto the chest in the paravertebral region from the middle of the scapula to its lower angle.

Segment S7 (medial basal) of the right lung. Refers to the lower lobe of the right lung. Topographically localized on the inner surface of the right lung, located below the root of the right lung. It is projected onto the chest from the 6th rib to the diaphragm between the sternum and midclavicular lines.

Segment S8 (anterior basal) of the right lung. Refers to the lower lobe of the right lung. Topographically delimited anteriorly by the main interlobar groove, inferiorly by the diaphragm, and posteriorly by the posterior axillary line.

Segment S9 (lateral basal) of the right lung. Refers to the lower lobe of the right lung. Topographically projected onto the chest between the scapular and posterior axillary lines from the middle of the scapula to the diaphragm.

Segment S10 (posterior basal) of the right lung. Refers to the lower lobe of the right lung. Topographically projected onto the chest from the lower angle of the scapula to the diaphragm, delimited on the sides by the paravertebral and scapular lines.

Segment S1+2 (apical-posterior) of the left lung. It is a combination of C1 and C2 segments, which is due to the presence of a common bronchus. Refers to the upper lobe of the left lung. Topographically projected onto the chest along the anterior surface from the 2nd rib and upward, through the apex to the middle of the scapula.

Segment S3 (anterior) of the left lung. Refers to the upper lobe of the left lung. Topographically, the 2nd to 4th ribs are projected onto the chest in front.

Segment S4 (superior lingular) of the left lung. Refers to the upper lobe of the left lung. Topographically projected onto the chest along the anterior surface of the 4th to 5th ribs.

Segment S5 (lower lingular) of the left lung. Refers to the upper lobe of the left lung. Topographically projected onto the chest along the anterior surface from the 5th rib to the diaphragm.

Segment S6 (superior basal) of the left lung. Refers to the lower lobe of the left lung. Topographically projected onto the chest in the paravertebral region from the middle of the scapula to its lower angle.

Segment S8 (anterior basal) of the left lung. Refers to the lower lobe of the left lung. Topographically delimited anteriorly by the main interlobar groove, inferiorly by the diaphragm, and posteriorly by the posterior axillary line.

Segment S9 (lateral basal) of the left lung. Refers to the lower lobe of the left lung. Topographically projected onto the chest between the scapular and posterior axillary lines from the middle of the scapula to the diaphragm.

Segment S10 (posterior basal) of the left lung. Refers to the lower lobe of the left lung. Topographically projected onto the chest from the lower angle of the scapula to the diaphragm, delimited on the sides by the paravertebral and scapular lines.

An X-ray of the right lung is presented in a lateral projection indicating the topography of the interlobar fissures.

The lungs are located in the chest, occupying most of it, and are separated from each other by the mediastinum. The sizes of the lungs are unequal due to the higher position of the right dome of the diaphragm and the position of the heart, shifted to the left.

Each lung has lobes separated by deep fissures. The right lung consists of three lobes, the left - of two. The right upper lobe accounts for 20% of the lung tissue, the middle lobe - 8%, the lower right lobe - 25%, the upper left lobe - 23%, the lower left lobe - 24%.

The main interlobar fissures are projected on the right and left in the same way - from the level of the spinous process of the 3rd thoracic vertebra they are directed obliquely down and forward and cross the 6th rib at the place where its bony part transitions into the cartilaginous part.

An additional interlobar fissure of the right lung is projected onto the chest along the 4th rib from the midaxillary line to the sternum.

The figure shows: Upper Lobe - upper lobe, Middle Lobe - middle lobe, Lower Lobe - lower lobe.

The lungs have 6 tubular systems: bronchi, pulmonary arteries and veins, bronchial arteries and veins, lymphatic vessels.

Most of the branches of these systems run parallel to each other, forming vascular-bronchial bundles, which form the basis of the internal topography of the lung. According to the vascular-bronchial bundles, each lobe of the lung consists of separate sections called bronchopulmonary segments.

Bronchopulmonary segment- this is the part of the lung corresponding to the primary branch of the lobar bronchus and the accompanying branches of the pulmonary artery and other vessels. It is separated from neighboring segments by more or less pronounced connective tissue septa in which segmental veins pass. These veins have as their basin half the territory of each of the neighboring segments. The segments of the lung are shaped like irregular cones or pyramids, the tops of which are directed towards the hilum of the lung, and the bases towards the surface of the lung, where the boundaries between the segments are sometimes noticeable due to differences in pigmentation. Bronchopulmonary segments are functional and morphological units of the lung, within which some pathological processes are initially localized and the removal of which can be limited to some sparing operations instead of resections of an entire lobe or the entire lung. There are many classifications of segments.

Representatives of different specialties (surgeons, radiologists, anatomists) identify different numbers of segments (from 4 to 12).

According to the International Anatomical Nomenclature, 10 segments are distinguished in the right and left lungs.

The names of the segments are given according to their topography. The following segments are available.

Right lung.

There are three segments in the upper lobe of the right lung:

segmentum apicale (SI) occupies the superomedial portion of the upper lobe, enters the upper opening of the chest and fills the dome of the pleura;

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

segmentum anterius (SIII) is adjacent with its base to the anterior wall of the chest between the cartilages of the 1st and 4th ribs; it is adjacent to the right atrium and superior vena cava.

The middle lobe has two segments:

segmentum laterale (SIV) with its base directed forward and outward, and its apex upward and medially;

segmentum mediate (SV) is in contact with the anterior chest wall near the sternum, between the IV-VI ribs; it is adjacent to the heart and diaphragm.

There are 5 segments in the lower lobe:

segmentum apicale (superius) (SVI) occupies the wedge-shaped apex of the lower lobe and is located in the paravertebral region;

segmentum basale mediate (cardiacum) (SVII) base occupies the mediastinal and partly diaphragmatic surfaces of the lower lobe. It is adjacent to the right atrium and the inferior vena cava;
the base of the segmentum basdle anterius (SVIII) 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;

segmentum basale laterale (SIX) is 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;

segmentum basale posterius (SX) is located paravertebral; it lies posterior to all other segments of the lower lobe, penetrating deeply into the posterior part of the costophrenic sinus of the pleura.
Sometimes the segmentum subapicdte (subsuperius) is separated from this segment.

Left lung. The upper lobe of the left lung has 5 segments:

segmentum apicoposterius (SI+II) corresponds in shape and position to seg. apicale and seg. posterius of the 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. Can be in the form of 2 segments;

segmentum anterius (SIII) 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 the truncus pulmonalis;

segmentum lingulare superius (SIV) represents the area of ​​the upper lobe between the III-V ribs in front and IV-VI in the axillary region;

segmentum lingulare inferius (SV) 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 that are symmetrical to the segments of the lower lobe of the right lung and therefore have the same designations:

segmentum apicale (superius) (SVI) occupies a paravertebral position;

segmentum basale medidle (cardidcum) (SVII) in 83% of cases has a bronchus that begins with a common trunk with the bronchus of the next segment - segmentum basale anterius (SVIII). The latter is separated from the lingular segments of the upper lobe of the fissura obliqua and is involved in the formation of the costal, diaphragmatic and mediastinal surfaces of the lung;

segmentum basale laterale (SIX) occupies the costal surface of the lower lobe in the axillary region at the level of the XII-X ribs;

segmentum basale posterius (SX) is a large section of the lower lobe of the left lung located posterior to other segments; it comes into contact with the VII-X ribs, diaphragm, descending aorta and esophagus,

Segmentum subapicale (subsuperius) is unstable.

Educational video of the anatomy of the roots and segments of the lungs

The lungs (pulmones) represent the main respiratory organs, filling the entire chest cavity except the mediastinum. Gas exchange occurs in the lungs, that is, oxygen is absorbed from the air of the alveoli by red blood cells and carbon dioxide is released, which in the lumen of the alveoli breaks down into carbon dioxide and water. Thus, in the lungs there is a close connection of the airways, blood and lymphatic vessels and nerves. The combination of pathways for carrying air and blood in a special respiratory system can be traced from the early stages of embryonic and phylogenetic development. The supply of oxygen to the body depends on the degree of ventilation of various parts of the lungs, the relationship between ventilation and the speed of blood flow, blood saturation with hemoglobin, the rate of diffusion of gases through the alveolar-capillary membrane, the thickness and elasticity of the elastic framework of the lung tissue, etc. A change in at least one of these indicators leads to a violation respiratory physiology and can cause certain functional disorders.

The external structure of the lungs is quite simple (Fig. 303). The shape of the lung resembles a cone, where there is an apex (apex), base (basis), costal convex surface (fades costalis), diaphragmatic surface (fades diaphragmatica) and medial surface (facies medias). The last two surfaces are concave (Fig. 304). On the medial surface, the vertebral part (pars vertebralis), the mediastinal part (pars mediastinalis) and the cardiac pressure (impressio cardiaca) are distinguished. The left deep cardiac depression is complemented by a cardiac notch (incisura cardiaca). In addition, there are interlobar surfaces (fades interlobares). The anterior edge (margo anterior), separating the costal and medial surfaces, is distinguished; the lower edge (margo inferior) is at the junction of the costal and diaphragmatic surfaces. The lungs are covered with a thin visceral layer of pleura, through which the darker areas of connective tissue located between the bases of the lobules are visible. On the medial surface, the visceral pleura does not cover the hilus pulmonum, but descends below them in the form of a duplication called the pulmonary ligaments (ligg. pulmonalia).

At the gate of the right lung, the bronchus is located above, then the pulmonary artery and vein (Fig. 304). In the left lung there is a pulmonary artery at the top, then a bronchus and a vein (Fig. 305). All these formations form the root of the lungs (radix pulmonum). The root of the lung and the pulmonary ligament hold the lungs in a certain position. On the costal surface of the right lung there is a horizontal fissure (fissura horizontalis) and below it an oblique fissure (fissura obliqua). The horizontal fissure is located between the linea axillaris media and the linea sternalis of the chest and coincides with the direction of the IV rib, and the oblique fissure with the direction of the VI rib. At the back, starting from the linea axillaris to the linea vertebralis of the chest, there is one groove, representing a continuation of the horizontal groove. Due to these grooves in the right lung, the upper, middle and lower lobes are distinguished (lobi superior, medius et inferior). The largest lobe is the lower one, then comes the upper and middle - the smallest. In the left lung there are upper and lower lobes, separated by a horizontal fissure. Below the cardiac notch on the anterior edge there is a tongue (lingula pulmonis). This lung is slightly longer than the right one, which is due to the lower position of the left dome of the diaphragm.

Boundaries of the lungs. The tops of the lungs protrude onto the neck above the collarbone by 3-4 cm.

The lower border of the lungs is determined at the point of intersection of the rib with conditionally drawn lines on the chest: along the linea parasternalis - VI rib, along the linea medioclavicularis (mamillaris) - VII rib, along the linea axillaris media - VIII rib, along the linea scapularis - X rib, along the linea paravertebralis - at the head of the XI rib.

With maximum inspiration, the lower edge of the lungs, especially along the last two lines, drops by 5-7 cm. Naturally, the border of the visceral layer of the pleura coincides with the border of the lungs.

The anterior edge of the right and left lungs is projected onto the anterior surface of the chest differently. Starting from the apexes of the lungs, the edges run almost parallel at a distance of 1-1.5 cm from each other to the level of the cartilage of the 4th rib. In this place, the edge of the left lung deviates to the left by 4-5 cm, leaving the cartilage of the IV-V ribs not covered by the lung. This cardiac impression (impressio cardiaca) is filled with the heart. The anterior edge of the lungs at the sternal end of the VI rib passes into the lower edge, where the boundaries of both lungs coincide.

Internal structure of the lungs. Lung tissue is divided into non-parenchymal and parenchymal components. The first includes all bronchial branches, branches of the pulmonary artery and pulmonary vein (except for capillaries), lymphatic vessels and nerves, connective tissue layers lying between the lobules, around the bronchi and blood vessels, as well as the entire visceral pleura. The parenchymal part consists of alveoli - alveolar sacs and alveolar ducts with surrounding blood capillaries.

Bronchial architecture(Fig. 306). The right and left pulmonary bronchi at the hilum of the lungs are divided into lobar bronchi (bronchi lobares). All lobar bronchi pass under the large branches of the pulmonary artery, with the exception of the right upper lobe bronchus, which is located above the artery. The lobar bronchi are divided into segmental bronchi, which are successively divided in the form of an irregular dichotomy up to the 13th order, ending with a lobular bronchus (bronchus lobularis) with a diameter of about 1 mm. Each lung has up to 500 lobular bronchi. The wall of all bronchi contains cartilaginous rings and spiral plates, reinforced with collagen and elastic fibers and alternating with muscle elements. In the mucous membrane of the bronchial tree, mucous glands are richly developed (Fig. 307).

When the lobular bronchus divides, a qualitatively new formation arises - the terminal bronchi (bronchi terminates) with a diameter of 0.3 mm, which are already devoid of a cartilaginous base and are lined with a single-layer prismatic epithelium. The terminal bronchi, sequentially dividing, form bronchioles of the 1st and 2nd order (bronchioli), in the walls of which there is a well-developed muscular layer that can block the lumen of the bronchioles. They, in turn, are divided into respiratory bronchioles of the 1st, 2nd and 3rd order (bronchioli respiratorii). Respiratory bronchioles are characterized by the presence of communications directly with the alveolar ducts (Fig. 308). Respiratory bronchioles of the 3rd order communicate with 15-18 alveolar ducts (ductuli alveolares), the walls of which are formed by alveolar sacs (sacculi alveolares) containing alveoli (alveoli). The branching system of the 3rd order respiratory bronchiole develops into the lung acinus (Fig. 306).

308. Histological section of the lung parenchyma of a young woman showing many alveoli (A) that are partially connected to the alveolar duct (AD) or respiratory bronchiole (RB). RA is a branch of the pulmonary artery. × 90 (according to Weibel)

The structure of the alveoli. As mentioned above, the alveoli are part of the parenchyma and represent the final part of the air system where gas exchange takes place. The alveoli represent a protrusion of the alveolar ducts and sacs (Fig. 308). They have a cone-shaped base with an elliptical cross-section (Fig. 309). There are up to 300 million alveoli; they make up a surface equal to 70-80 m2, but the respiratory surface, i.e., the places of contact between the capillary endothelium and the alveolar epithelium, is smaller and equal to 30-50 m2. Alveolar air is separated from the blood capillaries by a biological membrane that regulates the diffusion of gases from the cavity of the alveoli into the blood and back. The alveoli are covered with small, large and loose flat cells. The latter are also able to phagocytose foreign particles. These cells are located on the basement membrane. The alveoli are surrounded by blood capillaries, their endothelial cells are in contact with the alveolar epithelium. Gas exchange occurs at the sites of these contacts. The thickness of the endothelial-epithelial membrane is 3-4 microns.

Between the basement membrane of the capillary and the basement membrane of the alveolar epithelium there is an interstitial zone containing elastic, collagen fibers and the finest fibrils, macrophages and fibroblasts. Fibrous formations give elasticity to the lung tissue; due to it, the act of exhalation is ensured.

Lung segments

The bronchopulmonary segments represent part of the parenchyma, which includes the segmental bronchus and artery. At the periphery, the segments are fused with each other and, in contrast to the pulmonary lobules, do not contain clear layers of connective tissue. Each segment is cone-shaped, the apex of which faces the hilum of the lung, and the base faces its surface. The branches of the pulmonary veins pass through the intersegmental junctions. There are 10 segments in each lung (Fig. 310, 311, 312).

Segments of the right lung

Segments of the upper lobe. 1. The apical segment (segmentum apicale) occupies the apex of the lung and has four intersegmental boundaries: two on the medial and two on the costal surface of the lung between the apical and anterior, apical and posterior segments. The area of ​​the segment on the costal surface is slightly smaller than on the medial surface. An approach to the structural elements of the portal segment (bronchus, artery and vein) is possible after dissection of the visceral pleura in front of the pulmonary portal along the phrenic nerve. The segmental bronchus is 1-2 cm long, sometimes extending through a common trunk with the posterior segmental bronchus. On the chest, the lower border of the segment corresponds to the lower edge of the second rib.

2. The posterior segment (segmentum posterius) is located dorsal to the apical segment and has five intersegmental boundaries: two are projected on the medial surface of the lung between the posterior and apical, posterior and upper segments of the lower lobe, and three boundaries are distinguished on the costal surface: between the apical and posterior, posterior and anterior, posterior and upper segments of the lower lobe of the lung. The border formed by the posterior and anterior segments is oriented vertically and ends below at the junction of fissura horizontalis and fissura obliqua. The border between the posterior and upper segments of the lower lobe corresponds to the posterior part of the fissura horizontalis. The approach to the bronchus, artery and vein of the posterior segment is carried out from the medial side when dissecting the pleura on the posterosuperior surface of the hilum or from the side of the initial section of the horizontal groove. The segmental bronchus is located between the artery and vein. The vein of the posterior segment merges with the vein of the anterior segment and flows into the pulmonary vein. The posterior segment is projected onto the surface of the chest between the II and IV ribs.

3. The anterior segment (segmentum anterius) is located in the anterior part of the upper lobe of the right lung and has five intersegmental boundaries: two - pass on the medial surface of the lung, separating the anterior and apical anterior and medial segments (middle lobe); three boundaries pass along the costal surface between the anterior and apical, anterior and posterior, anterior, lateral and medial segments of the middle lobe. The anterior segment artery arises from the superior branch of the pulmonary artery. The segmental vein is a tributary of the superior pulmonary vein and is located deeper than the segmental bronchus. The vessels and bronchus of the segment can be ligated after dissecting the medial pleura in front of the hilum of the lung. The segment is located at the level of the II - IV ribs.

Middle lobe segments. 4. The lateral segment (segmentum laterale) on the side of the medial surface of the lung is projected only in the form of a narrow strip above the oblique interlobar groove. The segmental bronchus is directed backward, so the segment occupies the posterior part of the middle lobe and is visible from the costal surface. It has five intersegmental boundaries: two on the medial surface between the lateral and medial, lateral and anterior segments of the lower lobe (the last boundary corresponds to the terminal part of the oblique interlobar groove), three boundaries on the costal surface of the lung, limited by the lateral and medial segments of the middle lobe (the first boundary runs vertically from the middle of the horizontal groove to the end of the oblique groove, the second is between the lateral and anterior segments and corresponds to the position of the horizontal groove; the last border of the lateral segment is in contact with the anterior and posterior segments of the lower lobe).

The segmental bronchus, artery and vein are located deep, they can only be approached along an oblique groove below the hilum of the lung. The segment corresponds to the space on the chest between the IV-VI ribs.

5. The medial segment (segmentum mediale) is visible on both the costal and medial surfaces of the middle lobe. It has four intersegmental boundaries: two separate the medial segment from the anterior segment of the upper lobe and the lateral segment of the lower lobe. The first border coincides with the anterior part of the horizontal groove, the second - with the oblique groove. There are also two intersegmental boundaries on the costal surface. One line begins at the midpoint of the anterior portion of the horizontal sulcus and descends toward the terminal portion of the oblique sulcus. The second border separates the medial segment from the anterior segment of the upper lobe and coincides with the position of the anterior horizontal groove.

The segmental artery arises from the inferior branch of the pulmonary artery. Sometimes together with the 4th segment artery. Below it is a segmental bronchus, and then a vein 1 cm long. Access to the segmental leg is possible below the hilum of the lung through the oblique interlobar groove. The border of the segment on the chest corresponds to the IV-VI ribs along the midaxillary line.

Segments of the lower lobe. 6. The upper segment (segmentum superius) occupies the apex of the lower lobe of the lung. The segment at the level of the III-VII ribs has two intersegmental boundaries: one between the upper segment of the lower lobe and the posterior segment of the upper lobe passes along the oblique groove, the second - between the upper and lower segments of the lower lobe. To determine the boundary between the upper and lower segments, it is necessary to conditionally extend the anterior part of the horizontal fissure of the lung from the place of its confluence with the oblique fissure.

The superior segment receives artery from the inferior branch of the pulmonary artery. Below the artery is the bronchus, and then the vein. Access to the gate of the segment is possible through the oblique interlobar groove. The visceral pleura is dissected from the costal surface.

7. The medial basal segment (segmentum basale mediale) is located on the medial surface below the hilum of the lungs, in contact with the right atrium and the inferior vena cava; has boundaries with the anterior, lateral and posterior segments. Occurs only in 30% of cases.

The segmental artery arises from the inferior branch of the pulmonary artery. The segmental bronchus is the highest branch of the lower lobe bronchus; the vein is located below the bronchus and joins the inferior right pulmonary vein.

8. The anterior basal segment (segmentum basale anterius) is located in the anterior part of the lower lobe. On the chest corresponds to the VI-VIII ribs along the mid-axillary line. It has three intersegmental boundaries: the first passes between the anterior and lateral segments of the middle lobe and corresponds to the oblique interlobar groove, the second - between the anterior and lateral segments; its projection on the medial surface coincides with the beginning of the pulmonary ligament; the third boundary runs between the anterior and superior segments of the lower lobe.

The segmental artery originates from the inferior branch of the pulmonary artery, the bronchus - from the branch of the inferior lobe bronchus, the vein joins the inferior pulmonary vein. The artery and bronchus can be observed under the visceral pleura at the bottom of the oblique interlobar groove, and the vein under the pulmonary ligament.

9. The lateral basal segment (segmentum basale laterale) is visible on the costal and diaphragmatic surfaces of the lung, between the VII-IX ribs along the posterior axillary line. It has three intersegmental boundaries: the first is between the lateral and anterior segments, the second is on the medial surface between the lateral and medial, the third is between the lateral and posterior segments.

The segmental artery and bronchus are located at the bottom of the oblique sulcus, and the vein is located under the pulmonary ligament.

10. The posterior basal segment (segmentum basale posterius) lies in the posterior part of the lower lobe, in contact with the spine. Occupies the space between the VII-X ribs. There are two intersegmental boundaries: the first is between the posterior and lateral segments, the second is between the posterior and superior. The segmental artery, bronchus and vein are located deep in the oblique sulcus; It is easier to approach them during surgery from the medial surface of the lower lobe of the lung.

Left lung segments

Segments of the upper lobe. 1. The apical segment (segmentum apicale) practically repeats the shape of the apical segment of the right lung. Above the gate are the artery, bronchus and vein of the segment.

2. The posterior segment (segmentum posterius) (Fig. 310) with its lower border descends to the level of the V rib. The apical and posterior segments are often combined into one segment.

3. The anterior segment (segmentum anterius) occupies the same position, only its lower intersegmental border runs horizontally along the third rib and separates the upper lingular segment.

4. The upper lingual segment (segmentum linguale superius) is located on the medial and costal surfaces at the level of the III-V ribs in front and along the midaxillary line between the IV-VI ribs.

5. The lower lingual segment (segmentum linguale inferius) is located below the previous segment. Its lower intersegmental border coincides with the interlobar groove. On the anterior edge of the lung between the upper and lower lingular segments there is a center of the cardiac notch of the lung.

Segments of the lower lobe coincide with the right lung.

6. Upper segment (segmentum superius).

7. The medial basal segment (segmentum basale mediale) is unstable.

8. Anterior basal segment (segmentum basale anterius).

9. Lateral basal segment (segmentum basale laterale).

10. Posterior basal segment (segmentum basale posterius)

Pleural sacs

The right and left pleural sacs of the chest cavity represent a derivative of the common body cavity (celoma). The walls of the chest cavity are covered with a parietal layer of the serous membrane - the pleura (pleura parietalis); The pulmonary pleura (pleura visceralis pulmonalis) fuses with the lung parenchyma. Between them there is a closed pleural cavity (cavum pleurae) with a small amount of fluid - about 20 ml. The pleura has a general structural plan, inherent in all serous membranes, i.e. the surface of the sheets facing each other is covered with mesothelium located on the basement membrane and a connective tissue fibrous base of 3-4 layers.

The parietal pleura covers the walls of the chest, fused with f. endothoracica. In the region of the ribs, the pleura firmly fuses with the periosteum. Depending on the position of the parietal layer, the costal, diaphragmatic and mediastinal pleura are distinguished. The latter is fused with the pericardium and at the top passes into the dome of the pleura (cupula pleurae), which rises 3-4 cm above the first rib, at the bottom it passes into the diaphragmatic pleura, in front and behind - into the costal pleura, and along the bronchus, artery and veins of the hilum of the lungs continues into visceral leaf. The parietal leaf is involved in the formation of three pleural sinuses: the right and left costodiaphragmatic (sinus costodiaphragmatici dexter et sinister) and the costomediastinal (sinus costomediastinalis). The first are located to the right and left of the dome of the diaphragm and are limited by the costal and diaphragmatic pleura. The costomediastinal sinus (sinus costomediastinalis) is unpaired, located opposite the cardiac notch of the left lung, formed by the costal and mediastinal layers. The pockets represent a reserve place in the pleural cavity, into which lung tissue enters during inspiration. During pathological processes, when blood and pus appear in the pleural sacs, they primarily accumulate in these sinuses. Adhesions as a consequence of inflammation of the pleura primarily occur in the pleural sinuses.

Boundaries of the parietal pleura

The parietal pleura occupies a larger area than the visceral pleura. The left pleural cavity is longer and narrower than the right. The parietal pleura at the top grows to the head of the 1st rib and the formed pleural dome (cupula pleurae) protrudes above the 1st rib by 3-4 cm. This space is filled with the apex of the lung. At the back, the parietal layer descends to the head of the XII rib, where it passes into the diaphragmatic pleura; in front on the right side, starting from the capsule of the sternoclavicular joint, it descends to the VI rib along the inner surface of the sternum, passing into the diaphragmatic pleura. On the left, the parietal layer follows parallel to the right layer of the pleura to the cartilage of the IV rib, then deviates to the left by 3-5 cm and at the level of the VI rib passes into the diaphragmatic pleura. A triangular section of the pericardium, not covered by the pleura, grows to the IV-VI ribs (Fig. 313). The lower border of the parietal layer is determined at the intersection of the conventional lines of the chest and ribs: along the linea parasternal - the lower edge of the VI rib, along the linea medioclavicularis - the lower edge of the VII rib, along the linea axillaris media - the X rib, along the linea scapularis - the XI rib, along the linea paravertebral - to the lower edge of the body of the XII thoracic vertebra.

Age-related features of the lungs and pleura

In a newborn, the relative volume of the upper lobes of the lung is less than in a child at the end of the first year of life. By the period of puberty, the lung increases in volume by 20 times compared to the lung of a newborn. The right lung develops more intensively. In a newborn, the walls of the alveoli contain few elastic fibers and a lot of loose connective tissue, which affects the elastic traction of the lungs and the rate of development of edema in pathological processes. Another feature is that in the first 5 years of life the number of alveoli and bronchial branching orders increases. The acinus only in a 7-year-old child resembles in structure the acini of an adult. The segmental structure is clearly expressed at all age periods of life. After 35-40 years, involutive changes occur, characteristic of all tissues of other organs. The epithelium of the respiratory tract becomes thinner, elastic and reticular fibers are resorbed and fragmented, they are replaced by low-stretch collagen fibers, and pneumosclerosis occurs.

In the pleural layers of the lungs up to 7 years of age, there is a parallel increase in the number of elastic fibers, and the multilayer mesothelial lining of the pleura decreases to one layer.

Breathing mechanism

The lung parenchyma contains elastic tissue, which is capable of occupying the original volume after stretching. Therefore, pulmonary respiration is possible if the air pressure in the airways is higher than outside. Air pressure difference from 8 to 15 mm Hg. Art. overcomes the resistance of the elastic tissue of the lung parenchyma. This occurs when the chest expands during inhalation, when the parietal layer of the pleura, together with the diaphragm and ribs, changes position, which leads to an increase in the pleural sacs. The visceral layer follows passively the parietal layer under the pressure of the difference in the air stream in the pleural cavities and lungs. The lung, located in sealed pleural sacs, fills all their pockets during the inhalation stage. During the exhalation stage, the muscles of the chest relax and the parietal layer of the pleura, together with the chest, approaches the center of the chest cavity. Lung tissue, due to elasticity, decreases in volume and pushes out air.

In cases where a lot of collagen fibers appear in the lung tissue (pneumosclerosis) and the elastic traction of the lungs is disrupted, exhalation is difficult, which leads to expansion of the lungs (emphysema) and impaired gas exchange (hypoxia).

If the parietal or visceral layer of the pleura is damaged, the tightness of the pleural cavity is disrupted and pneumothorax develops. In this case, the lung collapses and is switched off from respiratory function. When the defect in the pleura is eliminated and air is sucked out of the pleural sac, the lung is again included in breathing.

During inhalation, the dome of the diaphragm lowers by 3-4 cm and, thanks to the spiral-shaped structure of the ribs, their anterior ends move forward and upward. In newborns and children of the first years of life, breathing occurs due to the movement of the diaphragm, since the ribs do not have curvature.

During quiet breathing, the volume of inhalation and exhalation is 500 ml. This air fills predominantly the lower lobe of the lungs. The apices of the lungs practically do not participate in gas exchange. During quiet breathing, part of the alveoli remains closed due to contraction of the muscular layer of the 2nd and 3rd order respiratory bronchioles. Only during physical work and deep breathing is the entire lung tissue involved in gas exchange. The vital capacity of the lungs in men is 4-5.5 liters, in women - 3.5-4 liters and consists of respiratory, additional and reserve air. After maximum exhalation, 1000-1500 ml of residual air are retained in the lungs. During quiet breathing, the volume of air is 500 ml (breathing air). Additional air in a volume of 1500-1800 ml is placed at maximum inspiration. Reserve air in a volume of 1500-1800 ml is removed from the lungs when exhaling.

Respiratory movements occur reflexively 16-20 times per minute, but an arbitrary breathing frequency is also possible. During inhalation, when the pressure in the pleural cavity drops, a rush of venous blood occurs to the heart and the outflow of lymph through the thoracic duct improves. Thus, deep breathing has a beneficial effect on blood flow.

X-rays of the lungs

When radiography of the lungs, survey, direct and lateral, as well as targeted radiographs and tomographic examination are performed. In addition, you can study the bronchial tree by filling the bronchi with contrast agents (bronchogram).

An anterior view of the panoramic image shows the organs of the thoracic cavity, chest, diaphragm and partly the liver. The x-ray shows the right (larger) and left (smaller) pulmonary fields, bounded below by the liver and in the middle by the heart and aorta. The pulmonary fields are formed by a clear shadow of the pulmonary blood vessels, well contoured against a light background formed by connective tissue layers and the air shadow of the alveoli and small bronchi. Therefore, per unit of their volume there is a lot of air tissue. The pulmonary pattern against the background of the pulmonary fields consists of short stripes, circles, and dots with smooth contours. This pulmonary pattern disappears if the lung loses its airiness as a result of edema or collapse of the lung tissue (atelectasis); When lung tissue is destroyed, lighter areas are noted. The boundaries of lobes, segments, and lobules are not normally visible.

A more intense shadow of the lung is normally observed due to the layering of larger vessels. On the left, the root of the lung below is covered by the shadow of the heart, and above there is a clear and wide shadow of the pulmonary artery. On the right, the shadow of the lung root is less contrasting. Between the heart and the right pulmonary artery there is a light shadow from the intermediate and lower lobe bronchi. The right dome of the diaphragm is located on the VI-VII rib (during the inhalation phase) and is always higher than the left. Under the right lies the intense shadow of the liver, under the left is the air bubble of the vault of the stomach.

On a plain radiograph in a lateral projection, it is possible not only to examine the pulmonary field in more detail, but also to project the pulmonary segments, which in this position do not overlap each other. From this image you can create a diagram of the arrangement of segments. In a lateral photograph, the shadow is always more intense as a result of the overlap of the right and left lungs, but the structure of the nearest lung is more clearly defined. In the upper part of the image, the apexes of the lung are visible, on which the shadows of the neck and girdle of the upper limb are partially superimposed with a sharp anterior border: below, both domes of the diaphragm are visible, forming sharp angles of the costophrenic sinus with the ribs, in front is the sternum, behind is the spine, the posterior ends of the ribs and shoulder blades. The pulmonary field is divided into two lighter areas: the retrosternal, limited by the sternum, heart and aorta, and the retrocardiac, located between the heart and the spine.

The trachea is visible as a light stripe up to the level of the V thoracic vertebra.

A targeted radiograph complements survey photographs, reveals certain details with the best image and is more often used in the diagnosis of various pathological changes in the apex of the lungs and costophrenic sinuses than to identify normal structures.

Tomograms (layer-by-layer images) are especially effective for studying the lungs, since in this case the image shows a layer lying at a certain depth of the lung.

On bronchograms, after filling the bronchi with a contrast agent, which is injected through a catheter into the main, lobar, segmental and lobular bronchi, it is possible to trace the condition of the bronchial tree. Normal bronchi have smooth and clear contours, consistently decreasing in diameter. Contrasting bronchi are clearly visible in the shadow of the ribs and root of the lung. When you inhale, normal bronchi lengthen and expand; when you exhale, the opposite is true.

On direct angiogram a. pulmonalis has a length of 3 cm, a diameter of 2-3 cm and overlaps the shadow of the spine at the level of the VI thoracic vertebra. Here it is divided into right and left branches. All segmental arteries can then be differentiated. The veins of the upper and middle lobes connect into the superior pulmonary vein, which has an oblique position, and the veins of the lower lobe - into the inferior pulmonary vein, located horizontally in relation to the heart (Fig. 314, 315).

Phylogeny of the lungs

Aquatic animals have a gill apparatus, which is a derivative of the pharynx pouches. Gill slits develop in all vertebrates, but in terrestrials they exist only in the embryonic period (see Development of the Skull). In addition to the gill apparatus, the respiratory organs additionally include the epibranchial and labyrinthine apparatuses, which represent the recesses of the pharynx lying under the skin of the back. Many fish, in addition to gill respiration, have intestinal respiration. When air is swallowed, the blood vessels of the intestine absorb oxygen. In amphibians, the skin also serves as an additional respiratory organ. Accessory organs include the swim bladder, which communicates with the esophagus. The lungs are derived from paired multi-chambered swim bladders, similar to those found in lungfish and ganoid fish. These bladders, like the lungs, are supplied with blood by 4 gill arteries. Thus, the swim bladder initially transformed from an additional respiratory organ in aquatic animals into the main respiratory organ in terrestrial animals.

The evolution of the lungs lies in the fact that in a simple bladder numerous partitions and cavities appear to increase the vascular and epithelial surface, which comes into contact with air. Lungs were discovered in 1974 in the largest fish of the Amazon, Arapaima, which is strictly pulmonary-breathing. She has gill breathing only for the first 9 days of life. The sponge-shaped lungs are connected to blood vessels and the caudal cardinal vein. Blood from the lungs enters the large left posterior cardinal vein. The hepatic vein valve regulates blood flow so that the heart is supplied with arterial blood.

These data indicate that lower aquatic animals have all the transitional forms from aquatic to terrestrial respiration: gills, respiratory sacs, lungs. In amphibians and reptiles, the lungs are still poorly developed, since they have a small number of alveoli.

In birds, the lungs are poorly extensible and lie on the dorsal part of the chest cavity, not covered with pleura. The bronchi communicate with the air sacs located under the skin. During the flight of a bird, due to the compression of the air sacs by the wings, automatic ventilation of the lungs and air sacs occurs. A significant difference between the lungs of birds and the lungs of mammals is that the airways of birds do not end blindly, as in mammals, with alveoli, but with anastomosing air capillaries.

In all mammals, the lungs additionally develop branching bronchi that communicate with the alveoli. Only the alveolar ducts represent the remnant of the pulmonary cavity of amphibians and reptiles. In mammals, in addition to the formation of lobes and segments, the separation of the central respiratory tract and the alveolar part occurred in the lungs. The alveoli develop especially significantly. For example, the area of ​​the alveoli in a cat is 7 m2, and in a horse it is 500 m2.

Embryogenesis of the lungs

The formation of the lungs begins with the formation of an alveolar sac from the ventral wall of the esophagus, covered with columnar epithelium. At the 4th week of embryonic development, three sacs appear in the right lung, and two in the left. The mesenchyme surrounding the sacs forms the connective tissue base and bronchi into which blood vessels grow. The pleura arises from the somatopleura and splanchnopleura, which line the secondary cavity of the embryo.