X-ray anatomy of the trachea, bronchi, lungs and pleura

On an X-ray, the trachea and main bronchi are visible due to the presence of air in them - the trachea as a light cylindrical formation against the background of the shadow of the spine. The main bronchi form light stripes above the shadow of the heart. Examination of the remaining sections of the bronchial tree (bronchography) is possible after the introduction of a contrast agent into the trachea and bronchi. The lungs of a living person are visible during fluoroscopy or radiography against the background of the chest as air pulmonary fields (right and left), separated from each other by an intense median shadow formed by the spine, sternum, heart protruding to the left and large vessels. The shadows of the clavicles (above) and ribs are superimposed on the pulmonary fields. In the spaces between the ribs, a mesh-like pulmonary pattern is visible, on which spots and strands are superimposed - shadows from the bronchi and blood vessels of the lung. In the area of the lung roots (at the level of the anterior ends of the II-V ribs), the shadows from larger bronchi and vessels with thicker walls are more pronounced. During X-ray examination during inhalation, the lung fields are more visible, and the pulmonary pattern is more clearly visible. Using tomography (layered radiography), it is possible to obtain pictures of individual deep layers of the lung with its bronchi and vessels.

Innervation: branches of the vagus nerve and the sympathetic trunk, which form the pulmonary plexus in the area of the root of each lung. Branches of the pulmonary plexus around the bronchi and vessels penetrate into the thickness of the lung, where they form peribronchial plexuses.

Blood supply: arterial blood for the nutrition of the lung tissue, including the bronchi, comes through the bronchial arteries (from the thoracic part of the aorta). The bronchial veins are tributaries of the pulmonary veins, the azygos and hemiazygos veins. Venous blood comes to the lungs through the pulmonary arteries. Enriched with oxygen during gas exchange, losing carbon dioxide, the blood turns into arterial. Arterial blood flows through the pulmonary veins into the left atrium.

Lymph drainage: bronchopulmonary, lower and upper tracheobronchial lymph nodes.

The first division of the lung into lobes was developed by the Swiss anatomist Aeby (1880). The first mention of a lung segment (as a term) is found in the work of Kramer and Glass (1932), who called a segment a section of the lung that is part of a lobe and ventilated by a constant segmental bronchus, supplied with a corresponding branch of the pulmonary artery. The veins that drain blood from the segments pass through the connective tissue septa between adjacent segments. The segments of the lung have the shape of an irregular truncated cone, the apex of which is directed toward the root, and the base toward the surface of the lung, and are covered with visceral pleura.

At present, the classification of pulmonary segments approved by the Congress of Otolaryngologists and the Society of Thoracic Specialists in 1949 in London has received the greatest application and distribution among clinicians. The development of this unified international nomenclature was facilitated by the creation of a special committee consisting of the leading specialists in the anatomy of the lungs and bronchology (Jackson, Brock, Sulya, etc.). This classification was supplemented at the VI International Congress of Anatomists in Paris (1955) and the VIII All-Union Congress of Anatomists, Histologists, and Embryologists in Tashkent (1974).

Each lung is divided into lobes by means of interlobar fissures, into which penetrates the visceral pleura, covering the interlobar surfaces of the lung, but not reaching 1-2 cm to the root of the lung.

It is known that the right lung consists of 3 lobes, the left - of 2 lobes. In the right lung, 10 segments are usually distinguished, in the left - 8.

The upper lobe of the right lung is divided into 3 segments: apical (1), posterior (2), and anterior (3). In the upper lobe, both in adults and children, pneumonia, tuberculous infiltrates, and cavities are quite often localized.

In the middle lobe, 2 segments are distinguished: lateral (4) and medial (5).

The lower lobe is divided into 5 segments: the upper, or Nelson's bronchus (6), the mediobasal, or cardiac (7), the anterior basal (8), the lateral basal (9), and the posterobasal (10). Cancer, pneumonia, and tuberculous cavities are often localized in S6. S8, S9, and S10 are quite often affected by bronchiectasis and abscesses.

In the upper lobe of the left lung, 4 segments are distinguished: apical-posterior (1+2), anterior (3), superior lingual (4), inferior lingual (5). During radiographic examination, it is difficult to accurately draw the boundaries between the two lingual segments, but the pathological process quite often affects both segments.

The lower lobe of the left lung contains 4 segments: superior (6), anterior basal (8), lateral basal (9), posterobasal (10).

However, this classification is not without its shortcomings, since it does not take into account the concepts of "lung zone" and "zonal bronchus" proposed by I. O. Lerner (1948), B. E. Lindberg (1948), Yu. N. Sokolov and L. S. Rosenstrauch (1958). According to their classification, each lung is divided into 4 zones. On the right: the upper lobe is the upper zone, the middle lobe is the anterior zone, segment VI is the posterior zone (or Fowler's apex), and the basal segments are the lower zone. On the left: the apical-posterior and anterior segments are the upper zone, the lingular bronchi are the anterior zone, segment VI is the posterior zone, and the basal segments are the lower zone.