Segments of the lungs on radiographs: structure, topography, and pathology


Radiography is the main method that is used for the diagnosis of diseases of the respiratory system, and in particular, the lungs. This is due to the fact that light is a body which is located inside the chest cavity, and inaccessible to survey by other methods. However, many diseases cause a change in the lung tissue, and doctors need to be able to visualize lung tissue for accurate diagnosis. Therefore x-rays have found widespread use in the United States.

Features of the structure of the lungs

The lungs are responsible for gas exchange between the blood and the environment. Grooves divide the light into multiple shares. The right lung consists of three, and the left of two lobes. Share, in turn, consist of segments. They represent truncated cones, of which apex is directed towards the pulmonary roots. The latter are grooves on both of the lungs from the mediastinum and the lungs consists of the pulmonary artery and veins leave the lungs. Of them in each segment enters the branch pulmonary arteries, and segmental bronchi, which are divided into two main bronchus.

They occupy a Central position in the segment, and between them, inside partitions of connective tissue are veins. The number of segments in different lobes of the lung. Right 10:

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

On the left in both lobes of a 4 segment, 8.

What are the segments?

Inside segment consists of lobules, which have dimensions of about 20 by 15 millimeters, and facing their bases to the outside of the segment. Segmental bronchus divides into terminal bronchioles, and is included in each of the many peaks. Segments themselves consist of the main functional units of lung acini. They provide gas exchange between the blood that flows through their capillaries and air, in their cavity.

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On the radiograph, the physician can see the lobes and segments. For easier analysis of images the image light is divided into three conditional parts, conducting horizontal boundaries.

Topography of the normal lung

Topographically in the lungs isolated areas tops, which are located above the shadows of the clavicles. Below the collarbone starts on the upper part of the lungs-the lower boundary of which is the front segments of the second ribs. From the second to the fourth costal segment are medium-sized departments, and down from them is lower. Thus, there are three landmarks on the radiograph of the clavicle, and front ends of the second and fourth pairs of ribs.

If we draw a vertical through the point where the clavicle intersects with the outer contour of the ribs and the middle of the clavicle, the lung field is divided into internal, external and medial zones.

Because the segments are superimposed on each other, their detailed study is performed on the image in the lateral projection.

The right lung presents ten segments. The dome is the 1st segment of the elite. From its rear surface S2 starts on the back of the upper lobe, and from pregnenalone – C3.

C4 is middle lobe is on the outside, is located between the horizontal slot and the lower divisions scythe. Front is C5.

If you draw an imaginary line from the extension interlobar fissure ago, it will be the lower border of 6th segment of the lower lobe. Segments at C7 C10 located in its base. The most medial of the 7th, he superimposed on the 8th and 9th, lateral. The back is C10.

Left their location is somewhat different. C1-C3 are combined in a large sidewalkstory segment. At the bottom, in place of the middle lobe is the ray segment, which is divided into C4 and C5.

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Indications for research

A panoramic radiograph of the chest cavity is a routine method of investigation. Moreover, fluoroscopy, which is a modification of this research should be carried out to all healthy people about once a year.

When the patient arrives at the hospital, doctors in most cases prescribe x-rays as necessary to ensure that in the lung fields no pathological changes that could be signs of early stages of the disease. Because some abnormalities may be detected with this method before a person will be complaints.

In order to be assigned to the x-ray must present the following symptoms:

  • Cough.
  • Complaints of shortness of breath.
  • Complaints of shortness of breath.
  • Whistles when breathing.
  • Wheezing when breathing.
  • The change in respiratory movements of the chest.
  • Chest pain, especially with breathing.
  • Swelling in the legs.
  • Mantoux different from normal.

The analysis of the image light

Thus, x-rays can be analyzed in stages, which allows physicians not to overlook inconspicuous, at first glance, the change. However, we must remember that this is a conditional division, and radiological areas are not equivalent to pulmonary segments. First you need to assess their symmetry, and obvious defects. They can be represented as elements of a blackout or enlightenment, and change the shape and size of the lungs, as well as a violation of their contours.

Since lungs filled with air, which passes x-rays, the x-ray they look like a light fabric with high transparency.

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

Because from the roots to the periphery of the vessels and bronchi are divided into smaller branches, which are worse than seen on x-rays, the intensity pattern from the center to the periphery is reduced. He becomes paler and almost does not vary at the outer edges of the lungs. He also depleted in the upper part, becoming most dense at the bottom.

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Pathology detected in the images

Almost all of the diseases that can occur in the lungs, change the density of their fabric and its lightness. On the radiograph it appears as areas of dim or enlightenment. For example, segmental pneumonia leads to infiltration of tissues by leukocytes and macrophages, vasodilation, and as a result, swelling. As a result, the plot becomes more dense, worse skips the x-rays and is visible on the image area of the blackout.

We have to carefully examine the region of the roots of lung pattern. Their gain says anything about the early stages of the inflammatory process, or the obstacle to the outflow of blood, such as thrombosis, edema in heart failure. Knowledge of the segmental structure may help in the differential diagnosis. So, tuberculosis most often affects the apical segments, as they have a poor oxygenation that enables bacteria to easily grow and multiply. But pneumonia often develop in the lower and middle divisions.