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Right lung how many lobes. X-ray lungs cheat sheet

Radiography is the main method used to diagnose diseases respiratory system, and, in particular, the lungs. This is due to the fact that the lungs are an organ that is located inside the chest cavity and is inaccessible 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. Right lung consists of three, and the left - 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 between them, inside partitions made of connective tissue, veins pass through. 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 of the lungs - the 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 zones of the apexes, which 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 middle beat located outside, located between the horizontal slot and lower sections 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 of the 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 pulmonary fields No pathological changes which may be signs initial stages diseases. 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.
  • Changes in respiratory movements of the 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. He is educated small branches 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 with leukocytes and macrophages, expansion blood vessels, and, as a result, swelling. 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 the 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.

Due to the successful development surgical methods treatment of lung diseases, there is an urgent need for topical diagnostics, for which division right lung by three beats, and the left by two was clearly insufficient.

Observations show that the occurrence and spread of disease processes in the lungs is most often limited to areas called segments. This dictates the need for a detailed study of intrapulmonary anatomical relationships, with which pathologists should be familiar.

In 1955, at the International Congress of Anatomists in Paris, the international nomenclature of bronchi and segments was adopted, according to which each lung consists of 10 segments. Each segment has its own segmental bronchus and branch of the pulmonary artery. Large veins pass between segments, marking their boundaries.

Segmental bronchi have precise designations and numbering.

The lung segments corresponding to the segmental bronchi have the same numbering and the same designations as the bronchi. In their shape, they are similar to irregular cones or pyramids, with their apexes facing the hilum of the lungs and their bases facing the surface of the lungs.

So, in each lung at present, according to international nomenclature, adopted International Congress anatomists in Paris in 1955, 10 segments are distinguished, each of which has its own segmental bronchus and a branch of the pulmonary artery. Intersegmental veins pass between the segments, marking the boundaries of the segments.

Right lung

It distinguishes the following 10 segments (according to D. A. Zhdanov) (Fig. 34, L, B).

1. Segmentum apicale (apical segment of the upper lobe) - cone-shaped superomedial section of the upper lobe, fills the dome pleural cavity. Its bronchus goes vertically upward.

Rice. 34.

(according to D. A. Zhdanov),

A-right lung, lateral surface; B-right lung, medial surface; B-left lung, lateral surface; L-left lung, medial surface.

2. Segmentum posterius (posterior segment of the upper lobe) has the appearance of a wide cone, with the base facing posteriorly and the apex towards the upper lobe bronchus. It borders on the II and IV ribs.

3. Segmentum anterius (anterior segment of the upper lobe) has a wide base adjacent to the anterior wall of the chest, between the cartilages of the 1st and 4th ribs, and its apex faces medially from the upper lobe bronchus. It borders the right atrium and the superior vena cava.

4. Segmentum laterale (lateral segment of the middle lobe) has the appearance of a triangular pyramid, with the base facing forward and outward, and the apex upward and medially.

5. Segmentum mediate (middle segment of the middle lobe) borders the heart and diaphragm, adjacent to the anterior wall of the chest near the sternum, between the IV and VI ribs.

6. Segmentum apicale (apical segment of the lower lobe) is represented by the wedge-shaped apex of the lower lobe and is located in the paravertebral region.

7. Segmentum basale mediate (cardiacum) (basal median, cardiac, segment of the lower lobe) in the shape of a pyramid, the base occupies the diaphragmatic and mediastinal surfaces of the lower lobe, the apex is directed to the intermediate bronchus. It borders the right atrium and the inferior vena cava.

8. Segmentum basale anterius (basal anterior segment of the lower lobe) in the form of a truncated pyramid, with the base on the diaphragmatic surface of the lower lobe, and the lateral side adjacent to chest wall in the axillary region between the VI and VIII ribs.

9. Segmentum basale laterale (basal lateral segment of the lower lobe) in the form of a small pyramid with a base on the diaphragmatic surface of the lower lobe; Its lateral surface is adjacent to the chest between the VII and IX ribs in the axillary region.

10. Segmentum basale posterius (basal posterior segment of the lower lobe) lies behind all other segments of the lower lobe, paravertebrally, entering into posterior section costophrenic sinus of the parietal pleura.

Left lung

It also distinguishes 10 segments (Fig. 34, C, D).

1. Segmentum apicale (apical segment of the upper lobe) corresponds to the apical segment of the upper lobe of the right lung. It borders on the aortic arch and subclavian artery.

2. Segmentum posterius (posterior segment of the upper lobe) has the shape of a cone, its base is adjacent to the posterior parts of the III and V ribs.

3. Segmentum anterius (anterior segment of the upper lobe), as well as symmetrical to it, with a wide base is adjacent to the anterior wall of the chest between the I-IV ribs, and its mediastinal surface is in contact with the trunk of the pulmonary artery.

4. Segmentum lingulare superius (upper lingular segment), with its base in the form of a wide strip, is adjacent to the chest wall in front between the III and V ribs, and in the axillary region to the IV-VI ribs. Corresponds to the lateral segment of the middle lobe of the right lung.

5. Segmentum lingulare inferius (lower lingular segment) lies below the previous one, but almost does not come into contact with the diaphragm. Corresponds to the median segment of the middle lobe of the right lung.

6. Segmentum apicale (apical segment of the lower lobe) is located paravertebrally.

7. Segmentum basale mediale cardiacum (basal median cardiac segment of the lower lobe).

8. Segmentum basale anterius (basal anterior segment of the lower lobe). Segments 7 and 8 very often have bronchi that begin with a common trunk. Segment 8 is separated from the lingular segments (4 and 5) by an oblique interlobar fissure and has surfaces - costal, diaphragmatic and mediastinal.

9. Segmentum basale laterale (basal lateral segment of the lower lobe) is located in the axillary region and is adjacent to the chest wall between the VII and X ribs.

10. Segmentum basale posterius (basal posterior segment of the lower lobe) - a large segment, located posterior to the other segments and in contact with the VIII and X ribs, the diaphragm, the esophagus and the descending aorta.

A. I. Strukov and I. M. Kodolova (1959) showed that even in a newborn, the segmental structure of the lungs is formed in the same way as in an adult. This is very important, as it allows us to draw a conclusion about the homogeneity of the prerequisites for bronchogenic spread pathological processes both in children and adults.

The peculiarities of the segmental structure of the lungs in children are only that the loose connective tissue layers between the segments in children are more clearly expressed than in adults. This is a good guide for establishing segment boundaries. In adults, the boundaries of the segments are poorly visible and difficult to establish.

At the department pathological anatomy I Moscow medical institute named after I.M. Sechenov, a technique for opening the bronchial tree has been developed, which boils down to the following.

The specimen of the thoracic cavity organs is placed on the preparation table with the anterior surface downwards and the posterior surface upwards, with the tongue towards you. The trachea, main and lobar bronchi are cut with blunt scissors. Next, the segmental and subsegmental bronchi are opened with small scissors using a grooved probe.

Based on the direction of the probe inserted into the segmental bronchus, its name and numbering are determined. This way the entire bronchial tree is examined down to its small branches.

At the same time, everything is being investigated pulmonary segments, which can be prepared using intersegmental veins that run superficially.

Some researchers pour colored or contrasting masses into the segmental bronchi.

Segments of the lungs in children are clearly distinguished in pneumonia, atelectasis, bronchogenic tuberculosis and other diseases.

The lungs are the main respiratory organs. They fill everything chest cavity with the exception of the mediastinum. Next, we will consider the main tasks of these bodies. The article will also describe the lobes and segments of the lungs.

Functions

Gas exchange occurs in the lungs. This process is the absorption of oxygen from the air of the alveoli by blood erythrocytes and the release of carbon dioxide, which breaks down in the lumen into water and gas. Thus, in the lungs there is a fairly close union of nerves, lymphatic and blood vessels, and the latter begins with early stages phylogenetic and embryonic development.

The level of oxygen supply to the body depends on the degree of ventilation, as well as on the intensity of blood flow, the diffuse velocity of gases through the alveolar-capillary membrane, the elasticity and thickness of the elastic frame, hemoglobin saturation and other factors. When any one indicator changes, a violation occurs and a number of functional disorders may occur.

Departments: general information

Human lung segments are sections of parenchyma. They include an artery and a bronchus. At the periphery, the elements are fused. Unlike the pulmonary lobules, the junction areas will not be contained by clear connective tissue layers. Each element is represented in the form of a cone. The apex is directed towards the gate of the lung, the base - towards the surface. The branches of the veins lie at the joints. In the left lung segments nine. IN neighboring organ There are 10 parts. The left lung includes two lobes. The right one consists of three parts. In this regard, their internal structure somewhat different. On the left in the lower lobe there are 4 segments. These include:

  1. Infero-posterior.
  2. Lower external.
  3. Lower internal.
  4. Upper.

There are also reed segments lungs:

  • Lower.
  • Upper.

It is considered more correct to distinguish four segments in the lower part of the left side. This is due to the fact that the lower anterior and internal departments include the common bronchus.

Segments of the right lung: posterior section

This area is located dorsal to the apical one. There are 5 boundaries in a segment. Two of them are projected between the apical, superior and posterior on medial surface. Three boundaries are on the costal surface. The bridge that forms the anterior and posterior segments of the lung has a vertical orientation. To the vein, artery and bronchus of the posterior element, it is carried out from the medial side in the dissection of the pleura of the portal surface or from the initial section of the horizontal groove. Between the vein and artery there is a segmental bronchus. The blood channel of the posterior element connects to the vessel of the anterior one. Together they enter Between the II and IV costal plates, the posterior segment is projected onto the surface of the sternum.

Front zone

This segment is located in the upper lobe. It can have five boundaries. Two lie along the medial surface. They separate the apical and anterior, anterior and medial segments of the lung. Three boundaries run along the surface of the ribs. They divide medial, anterior and lateral, posterior and anterior, apical and anterior segments. The artery arises from the superior main branch. Deeper than the bronchus is a vein. It is presented as an influx from the upper branch. The bronchus and vessels in the segment can be ligated in front of the hilum when dissecting the medial pleura. The anterior zone is located in the region of the II-IV ribs.

Lateral division

This segment is projected from the medial side only as a narrow strip lying above the interlobar oblique groove. The bronchus has a posterior orientation. In this regard, the segment is located on the back part in the middle lobe. It is visible from the surface of the ribs. There are five boundaries in the department. Two of them lie along the medial surface, separating the anterior and medial segments of the lung. The first boundary lies in accordance with the terminal portion of the oblique groove. The other three are located on the costal surface of the organ. They separate the medial and lateral segments light medium parts.

The first boundary runs vertically. It runs from the center of the horizontal furrow to the edge of the oblique. The second border runs between the anterior and lateral segments. It corresponds to the location of the horizontal groove. The third border is in contact with the posterior and anterior segments in the lower lobe. The vein, artery and bronchus are deep. The approach to them is only possible below the gate along an oblique furrow. The lateral segment is located in the area between the IV-VI ribs.

Medial department

It is visible on both the medial and costal surfaces in the middle lobe. There are four boundaries in the department. Two separate the medial section from the lateral in the lower and anterior in the upper lobes. The second border coincides with the oblique groove. The first one runs along the front part of the horizontal recess. There are also two boundaries along the costal surface. One starts from the middle of the anterior zone of the horizontal furrow, descending to the final section of the oblique. The second boundary separates the anterior segment from the medial one. The line coincides with the location of the horizontal groove. From lower branch artery gives off a segmental branch. Below it there is a bronchus and a centimeter vein. The segmental pedicle is approached from the lower part of the hilum through the interlobar oblique groove. The border on the chest is located in the area of ​​the IV-VI ribs along the axilla midline.

Upper part of the lower part

This segment is at the top. In the region of the III-VII ribs, there are two boundaries in the area. One runs between the superior segment in the lower lobe and the posterior segment in the upper lobe. The border runs along an oblique furrow. The second line goes to the upper and lower segments of the lower part. To determine the boundaries, the anterior region of the horizontal furrow should be approximately extended from its junction with the oblique. The artery of the inferior branch enters the upper segment common vessel. Below it is the bronchus, then the vein. Access to the gate is possible through an oblique interlobar groove.

Medial basal division

This segment is located on the medial side below pulmonary portal. The department is in contact with the right atrium. The segment is separated by a border from the posterior, lateral and anterior. A vessel extends from the lower branch of the artery into the department. Most high part The lower lobe bronchus is considered a segmental bronchus. Below it is a vein that flows into the lower right side basic.

Anterior basal section

This segment is located in the lower lobe, its anterior section. On the sternum, its location corresponds to the VI-VIII ribs of the axillary midline. There are three boundaries in the department. The first line runs between the lateral and anterior segments in the middle lobe. It corresponds to the oblique groove. The projection of the second border coincides on the medial surface with the beginning of the ligament. The third line runs between the upper and anterior segments. The artery begins from the inferior branch of the common arterial canal. The bronchus arises from the process of the lower lobe element of the same name. The vein enters the inferior main venous branch. The bronchus and artery are visible at the bottom of the oblique groove under the visceral pleura. A vein is found under the ligament.

Basal lateral division

This segment is visible on the diaphragmatic and costal sides of the lung. The department is located in the area between VII-IX plates along the axillary posterior line. It has three boundaries. The first passes between the anterior and lateral segments. The last and medial sections are separated by a second boundary. The third line runs between the posterior and lateral segments. The bronchus and artery lie along the bottom of the oblique groove, the vein - under the ligament.

Basal posterior section

This segment is located in the lower lobe. It is in contact with the spine. The segment occupies space in the area of ​​the VII-X ribs. There are two boundaries in the department. They separate the posterior segment from the superior and lateral. The vein, bronchus and artery run along the depth of the oblique groove. At surgical intervention they are best accessed from the medial side of the lower lobe.

Left lung segments

At the top there are the following sections:

  1. Apical. It almost repeats the shape of the segment of the same name in right lung. The vein, bronchus and artery are located above the hilum.
  2. Rear. Its lower border goes down to the V rib. The posterior and apical segments of the left lung are often combined into one.
  3. Front. Its lower border lies horizontally relative to the third rib.

Lingular segments of the left lung:

  1. Front. It is located on the costal and medial sides in the region of the III-V ribs and along the midaxillary line at the level of the IV-VI plates.
  2. Lower. It is located under the previous department. Its border coincides with the furrow. The lower and upper lingular segments of the lungs are divided in the middle by the center of the cardiac notch.

The sections of the lower part coincide with similar ones in the organ opposite.

Surgery: indications

If the functions of any area are impaired, its resection (removal) is carried out. This need may arise in the following cases:


Progress of the operation

As a rule, it is typical. Since the lungs are hidden in the sternum, an incision is made between the ribs for better access. Then the plates are moved apart using special tool. In accordance with the size of the affected area, resection of the anatomical and functional element is carried out. For example, it may be deleted lung segment. In various combinations, several sections can be subjected to resection at once.

An intervention may also involve removing a lobe of the organ. IN in rare cases marginal resection is performed. This operation is atypical. It involves suturing and removing the damaged area on outside lung As a rule, this type of resection is performed for injuries characterized by a small amount of damage.

Segments are morphofunctional elements of lung tissue, which include its own bronchus, artery and vein. They are surrounded by acini - the smallest functional unit pulmonary parenchyma (about 1.5 mm in diameter). The alveolar acini are ventilated by the bronchiole, the smallest branch of the bronchus. These structures ensure gas exchange between the surrounding air and blood capillaries.

Each of them has its own segmental structure.

Segments of the upper lobe of the right lung:

  1. Apical (S1).
  2. Rear (S2).
  3. Front (S3).

There are 2 structural segments in the middle lobe:

  1. External (S4).
  2. Internal (S5).

There are 5 segments in the lower lobe of the right lung:

  1. Upper (S6).
  2. Lower internal (S7).
  3. Inferoanterior (S8).
  4. Lower external (S9).
  5. Inferoposterior (S10).

The left lung has two lobes, so structural structure pulmonary parenchyma is somewhat different. The middle lobe of the left lung consists of the following segments:

  1. Upper reed (S4).
  2. Lower reed (S5).

The lower lobe has 4-5 segments (in different authors opinions differ):

  1. Upper (S6).
  2. Inferointernal (S7), which can be combined with inferoanterior (S8).
  3. Lower external (S9).
  4. Inferoposterior (S10).

It is more correct to distinguish 4 segments in the lower lobe of the left lung, since S7 and S8 have a common bronchus.

To summarize: the left lung consists of 9 segments, and the right lung has 10.

Topographic location of lung segments on a radiograph

X-ray, passing through the pulmonary parenchyma, does not clearly highlight topographical landmarks that allow localizing the segmental structure of the lungs. To learn how to determine the location of pathological dark spots in the lungs in an image, radiologists use markers.

The upper lobe is separated from the lower lobe (or middle lobe on the right) by an oblique interlobar fissure. It is not clearly visible on an x-ray. To highlight it, use the following guidelines:

  1. On straight shot begins at the level of the spinous process of Th3 (3rd thoracic vertebra).
  2. Runs horizontally along the outer part of the 4th rib.
  3. Then heads to highest point diaphragm in the projection of its middle part.
  4. In the lateral view, the horizontal pleura starts superiorly from Th3.
  5. Passes through the root of the lung.
  6. It ends at the highest point of the diaphragm.

A horizontal interlobar fissure separates upper lobe from the middle one in the right lung. She goes through:

  1. On a direct radiograph along the outer edge of the 4th rib - towards the root.
  2. In the lateral projection, it starts from the root and goes horizontally to the sternum.

Topography of lung segments:

  • apical (S1) runs along the 2nd rib to the scapular spine;
  • posterior – from the middle of the shoulder blade to its upper edge;
  • anterior – in front between the 2nd and 4th ribs;
  • lateral (upper lingular) – between the 4th and 6th ribs along the anterior axillary line;
  • medial (lower lingual) – between the 4th and 6th ribs closer to the sternum;
  • upper basal (S6) – from the middle of the scapula to the lower angle along the paravertebral region;
  • medial basal - from the 6th rib to the diaphragm between the midclavicular line and the sternum;
  • anterior basal (S8) – between the interlobar fissure in front and the axillary lines in the back;
  • lateral basal (S9) projects between the middle of the scapula and the posterior axillary line;
  • posterior basal (S10) - from the lower angle of the scapula to the diaphragm between the scapular and paravertebral lines.

On the left, the segmental structure is insignificantly different, which allows the radiologist to quite accurately localize pathological shadows in the pulmonary parenchyma on photographs in frontal and lateral projections.

Rare features of lung topography

In some people, due to the abnormal position of the azygos vein, lobus venae azygos is formed. She shouldn't be considered pathological formation, but must be taken into account when reading x-rays chest organs.

In most people, the venae azygos flows into the superior vena cava medially from the mediastinal surface of the right lung, and therefore is not visible on radiographs.

When identifying the lobe of the azygos vein, it is obvious that in a person the place of entry of this vessel is shifted somewhat to the right in the projection of the upper lobe.

There are cases when the azygos vein is located below its normal position and compresses the esophagus, making swallowing difficult. In this case, difficulties arise during the passage of food - dysphagialusoria (“nature’s joke”). On an x-ray, the pathology is manifested by a marginal filling defect, which is considered a sign of cancer. In fact, after performing (CT), the diagnosis is excluded.


Other rare lung lobes:

  1. The pericardium is formed in the wrong way medial section interlobar fissure.
  2. Lingular - can be seen on photographs when the interlobar fissure is located in the projection of the 4th rib on the left. It is a morphological analogue of the middle lobe on the right in 1-2% of people.
  3. Posterior – occurs when there is an additional gap separating top part the lower lobe from its base. Occurs on both sides.

Every radiologist should know the topography and segmental structure of the lungs. Without this, it is impossible to read chest X-rays correctly.

Segment S1+2 of the left lung. Represents a combination of C1 and C2 segments. Refers to the upper lobe of the left lung. Topographically projected onto 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.

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.

S4 segment (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, it is projected onto the chest with 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 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.

S8 segment (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.