Anatomical formation located in the posterior mediastinum. Topography of mediastinal organs. Superior and inferior mediastinum

Mediastinum(mediastinum)- part of the thoracic cavity, limited by the intrathoracic fascia, behind which there is the sternum in front, and the thoracic spine and neck of the ribs in the back; on the side - the mediastinal part of the parietal pleura; below - the diaphragm, covered with the phrenic-pleural fascia (part of the intrathoracic fascia); from above - the upper aperture of the chest.

The horizontal plane connecting the angle of the sternum with the disc between the IV and V thoracic vertebrae separates the upper mediastinum from the lower. The inferior mediastinum is divided into anterior, middle and inferior parts (mediastinum).

Key structure superior mediastinum (mediastinum superius)) is aortic arch - continuation of the ascending aorta. It begins at the level of the second right sternocostal joint, goes from front to back, from right to left and ends at the level of the body of the fourth thoracic vertebra. Three vessels depart from the aortic arch: brachiocephalic trunk, left common carotid And left subclavian artery(Fig. 11 ,A, color on). To the right of the initial part of the aortic arch is the superior vena cava. It is formed as a result of the connection right And left brachiocephalic veins. Before entering the fibrous pericardium, it flows into azygos vein. Along the lateral wall of the superior vena cava lies the right phrenic nerve.

Anterior to the aortic arch are:

• the anterior edge of the right and left lungs, covered with pleura;
• thymus (can extend to the neck or descend into the anterior mediastinum);
• the left vagus nerve (at the entrance to the upper aperture of the chest, it intersects with the left phrenic nerve);
• the left phrenic nerve with the pericardial diaphragmatic vessels (located outside the vagus nerve).

Posterior to the aortic arch are located:

• trachea (displaced to the right side from the midline);
• esophagus (lies behind the trachea, in front of the spinal column in direct contact with the right mediastinal part of the parietal pleura);
• right vagus nerve (lies along the lateral wall of the trachea);
• left recurrent laryngeal nerve (starts from the vagus nerve, bends around the aortic arch from below and lies in the groove between the esophagus and trachea);
• thoracic duct (at the level of IV-VI thoracic vertebrae, it crosses the midline from the right side to the left and goes to the upper aperture of the chest).

Below the aortic arch are localized:

• bifurcation of the pulmonary trunk;
• ductus arteriosus (ductus botallo; connects the pulmonary trunk to the aortic arch);
• left recurrent laryngeal nerve;
• left main bronchus.

Anterior mediastinum (mediastinum anterius) located between the posterior surface of the sternum and the pericardium. It contains the lower part of the thymus, fiber, parasternal and prepericardial lymph nodes.

Mediastinum medium contains the pericardium with the heart, phrenic nerves, pericardial diaphragmatic arteries and veins.

Pericardium) surrounds the heart and the initial sections of large vessels (the ascending aorta, the inferior vena cava and the pulmonary trunk). In relation to the sagittal plane, it is located asymmetrically: about 2/3 is located to the left of this plane, 1/3 is to the right. Skeletotopy and syntopy of the pericardium correspond to the topography of the heart. There are fibrous and serous pericardium.

Fibrous pericardium- This is the outer dense layer of connective tissue that continues into the adventitia of the aorta, pulmonary trunk, superior and inferior vena cava, and pulmonary veins. The fibrous pericardium fuses with the tendon center of the diaphragm and is connected by ligaments to the posterior surface of the sternum.

Serous pericardium consists of a parietal plate, which is adjacent to the inner surface of the fibrous pericardium, and a visceral plate (epicardium), which forms the outer lining of the heart wall.

Between the two plates of the serous pericardium there is a cavity containing a small amount of fluid (up to 25 ml). The pericardial cavity has two sinuses. The transverse sinus of the pericardium is bounded anteriorly by the ascending aorta and pulmonary trunk, posteriorly by the right atrium and the superior vena cava. The sinus can be entered behind the ascending aorta from both sides simultaneously. The oblique sinus of the pericardium is bounded anteriorly by the left atrium, posteriorly by the pericardium, on the left by the pulmonary veins, and on the right by the inferior vena cava. The sinus can only be entered from the left side, moving the heart up and to the right.

Blood supply The pericardium is carried out by the pericardial diaphragmatic arteries (from the system of internal thoracic arteries) and the pericardial branches of the thoracic aorta. The pericardium is innervated by the phrenic nerves. The sensory fibers in their composition provide pain sensitivity.

Heart (cog) - the central structure of the cardiovascular system. It is a hollow muscular organ located in the chest inside the pericardium. In front, the heart is covered by the mediastinal parts of the parietal pleura and partially by the lungs. Behind it are the organs of the posterior mediastinum.

The heart consists of two atria and two ventricles, separated by the interatrial and interventricular septa. Top of the heart directed forward, down and to the left. The apical impulse is normally determined in the 5th intercostal space on the left, 1 cm inward from the midclavicular line. Base of the heart and the great vessels associated with it (pulmonary trunk, aorta, vena cava and four pulmonary veins) are directed backward, upward and to the right. In this case, the aorta, which has an elastic wall, lies behind the pulmonary trunk, and the vena cava are located to the right of the right superior and inferior pulmonary veins. The base of the heart (its upper border) is projected onto the anterior surface of the chest along a line connecting the point located along the upper edge of the 3rd rib at a distance of 1 cm from the right edge of the sternum with a point located along the lower edge of the 2nd rib at a distance of 2.5 cm from left edge of the sternum.

Sternocostal (anterior) surface the heart is convex and faces forward towards the sternum and ribs. It is formed predominantly by the right ventricle. Bottom (diaphragmatic) surface formed mainly by the left ventricle. The boundaries between the ventricles on the anterior and inferior surfaces of the heart are the anterior and posterior interventricular grooves. The coronary groove goes around the heart to the left and passes at the border between the atria and ventricles. The right edge of the heart is sharp, the left is rounded. Normally, the right border of the heart is projected along a line spaced one finger width from the right edge of the sternum along the cartilage of the third rib to the 6th costosternal joint. The left border of the heart begins at a point located at a distance of 2.5 cm from the edge of the sternum at the level of the lower edge of the cartilage of the second rib, and ends in the area of ​​the apex beat.

All cardiac openings are projected onto the surface of the chest along a line connecting the cartilage of the third left rib along the sternal line with the place of articulation of the sixth right rib with the sternum:

• the opening of the pulmonary trunk is at the edge of the sternum at the level of the upper edge of the 3rd left sternocostal joint. The pulmonary valve is heard in the 2nd intercostal space on the left at the edge of the sternum;
• the opening of the aorta is behind the sternum below and medial to the opening of the pulmonary trunk. The aortic valve is heard in the 2nd intercostal space on the right at the edge of the sternum;
• left atrioventricular foramen - near the midline at the level of attachment of the fourth left rib to the sternum. The bicuspid valve, located in the left atrioventricular orifice, is heard at the apex of the heart;
• right atrioventricular foramen - at the level of the 4th intercostal space closer to the right side of the sternum. The tricuspid valve, located in the right atrioventricular foramen, is heard at the base of the xiphoid process.

The heart is supplied by the right and left coronary arteries, which begin from the ascending aorta (right and left aortic sinuses, sinuses of Valsalva). Right coronary artery (a. coronaria dextra) goes around the right edge of the heart. Her posterior interventricular branch in the groove of the same name it goes to the apex of the heart, where it anastomoses with anterior interventricular branch(from the left coronary artery). The right coronary artery supplies the: right atrium, most of the right ventricle (including the papillary muscles), the diaphragmatic surface of the left ventricle (including the posterior papillary muscle), the interatrial septum and the posterior 1/3 of the interventricular septum, the sinus node (60% of cases) and the atrioventricular node of the cardiac conduction system.

Left coronary artery (a. coronaria sinistra) passes between the left ear and the pulmonary trunk and gives off two branches. The circumflex branch is a continuation of the main trunk; is directed to the posterior surface of the heart, lies in the coronary sulcus and anastomoses with the right coronary artery. The anterior interventricular branch along the groove of the same name reaches the apex of the heart. The left coronary artery supplies blood to the left atrium, the walls of the left ventricle, the anterior wall of the right ventricle, the anterior 2/3 of the interventricular septum, and the sinus node (40% of cases).

The heart is innervated from the cardiac plexus, which lies at its base. It is divided into a superficial part, located on the concave side of the aortic arch, in front of the right pulmonary artery, and a deep part, located between the aortic arch and the tracheal bifurcation. Afferent and parasympathetic fibers of the vagus nerve take part in the formation of the plexus (they are part of its cervical and thoracic cardiac branches), sympathetic and sensory fibers of the spinal nature (contained in cervical cardiac nerves And thoracic cardiac branches). The cardiac plexus continues along the course of the coronary arteries and becomes a plexus localized under the epicardium in the walls of the atria and ventricles. The cardiac nerves, originating from the vagus nerve, lie on the anterior surface of the lower third of the trachea and come into contact with the lymph nodes located here. Therefore, when the nodes enlarge, for example in pulmonary tuberculosis, they can be compressed by them, which leads to a change in the rhythm of heart contraction. Irritation of parasympathetic fibers not only reduces the frequency and strength of heart contractions, but also causes a narrowing of the coronary arteries. Activation of the sympathetic nervous system has the opposite effect. Myocardial infarction is characterized by pain behind the sternum radiating to the shoulder, scapula and left arm. This is due to the fact that the afferent nerve fibers going to the heart are processes of neurons of the four upper thoracic spinal ganglia. The skin of the chest is innervated from these same nodes. (intercostal nerves) and upper limb (intercostal-brachial nerves).

The autonomic nervous system regulates the heart rate, but the rhythm and sequence of contractions of the heart chambers is set by specialized cardiomyocytes located in sinoatrial node. This node is located in the wall of the right atrium next to the opening of the superior vena cava and is the pacemaker of the heart (pacemaker). From the sinoatrial node the excitation reaches atrioventricular node and further spreads throughout atrioventricular bundle(bundle of His), its right and left legs, subendocardial branches. The listed structures are part of the conduction system of the heart, damage to which is manifested by arrhythmia or heart block: hypertrophy of the wall of the right atrium can cause attacks of paroxysmal tachycardia due to mechanical irritation of the sinoatrial node. After a myocardial infarction, a transverse heart block often develops in the left coronary artery basin (the ventricles contract independently of the atria with a frequency of 30-40 beats per minute). This is due to the formation of a scar in the interventricular septum and a violation of the conduction of excitation generated in the sinoatrial node along the His bundle to the ventricular myocardium.

Posterior mediastinum (mediastinumposterius) limited: behind - by the thoracic vertebrae, in front - by the pericardium, on the sides - by the mediastinal part of the parietal pleura, above - by a horizontal plane drawn through the angle of the sternum (Fig. 12, color incl.).

The posterior mediastinum includes:

descending aorta (thoracic aorta) - first lies to the left of the spinal column, then shifts to the midline. It has two groups of branches:

© parietal branches (posterior intercostal arteries, subcostal and superior phrenic arteries);

° visceral branches (mediastinal, bronchial, pericardial and esophageal);

• esophagus - at the level of the IV thoracic vertebra it lies to the right of the midline, and at the level of the VIII-XIV thoracic vertebrae - in front of the thoracic aorta and spine;
• azygos vein - to the right of the spinal column it rises to the level of the IV thoracic vertebra, forms an arch above the root of the right lung and flows into the superior vena cava. The tributaries of the azygos vein are the right posterior intercostal veins, the right superior intercostal vein, the hemizygos vein, bronchial, esophageal and mediastinal veins;
• hemizygos vein - enters the chest cavity, piercing the left leg of the diaphragm; at the level of VHI of the thoracic vertebra it shifts to the right side and flows into the azygos vein. The tributaries of the hemizygos vein are the 9th-11th left posterior intercostal veins and the accessory hemizygos vein;
• accessory hemizygos vein - descends along the left side of the spinal column, collects blood from the 4th-8th intercostal spaces and flows into the hemizygos vein;
• thoracic duct - enters the thoracic cavity through the aortic opening, lies between the azygos vein and the descending part of the aorta, reaches the level of the IV-VI thoracic vertebra, where it shifts to the left, and then leaves the thoracic cavity through the upper aperture;
• sympathetic trunk - usually located under the intrathoracic fascia at the level of the rib heads (therefore, formally it is not part of the posterior mediastinum). Consists of 12 nodes and internodal connections. Branches of the sympathetic trunk - large and small splanchnic nerves, white and gray connecting branches (spinal nerves).

• Clinicians more often use alternative names for the arteries of the heart - for example, the left anterior descending artery (LAD), the posterior descending artery (PDA), or the obtuse marginal branch (OM), instead of the left marginal branch of the left circumflex branch. coronary artery.

• Which doctors should you contact if you have malignant neoplasms of the anterior mediastinum?

What are malignant neoplasms of the anterior mediastinum?

Mediastinum is called the part of the thoracic cavity limited in front by the sternum, partially by the costal cartilages and retrosternal fascia, behind by the anterior surface of the thoracic spine, the necks of the ribs and prevertebral fascia, and on the sides by the layers of the mediastinal pleura. The mediastinum is limited below by the diaphragm, and above by a conventional horizontal plane drawn through the upper edge of the manubrium of the sternum.

The most convenient scheme for dividing the mediastinum, proposed in 1938 by Twining, is two horizontal (above and below the roots of the lungs) and two vertical planes (in front and behind the roots of the lungs). In the mediastinum, therefore, three sections (anterior, middle and posterior) and three floors (upper, middle and lower) can be distinguished.

In the anterior section of the superior mediastinum there are: the thymus gland, the upper section of the superior vena cava, the brachiocephalic veins, the aortic arch and its branches, the brachiocephalic trunk, the left common carotid artery, the left subclavian artery.

In the posterior part of the upper mediastinum there are: the esophagus, the thoracic lymphatic duct, the trunks of the sympathetic nerves, the vagus nerves, the nerve plexuses of the organs and vessels of the thoracic cavity, fascia and cellular spaces.

In the anterior mediastinum there are: fiber, spurs of the intrathoracic fascia, the leaves of which contain the internal mammary vessels, retrosternal lymph nodes, and anterior mediastinal nodes.

In the middle section of the mediastinum there are: the pericardium with the heart enclosed in it and the intrapericardial sections of large vessels, the bifurcation of the trachea and the main bronchi, the pulmonary arteries and veins, the phrenic nerves with the accompanying phrenic-pericardial vessels, fascial-cellular formations, and lymph nodes.

In the posterior part of the mediastinum there are: the descending aorta, azygos and semi-gypsy veins, trunks of sympathetic nerves, vagus nerves, esophagus, thoracic lymphatic duct, lymph nodes, tissue with spurs of the intrathoracic fascia surrounding the organs of the mediastinum.

According to the departments and floors of the mediastinum, certain preferential localizations of most of its neoplasms can be noted. Thus, it has been noticed, for example, that intrathoracic goiter is often located in the upper floor of the mediastinum, especially in its anterior section. Thymomas are found, as a rule, in the middle anterior mediastinum, pericardial cysts and lipomas - in the lower anterior. The upper floor of the middle mediastinum is the most common location of teratodermoids. In the middle floor of the middle part of the mediastinum, bronchogenic cysts are most often found, while gastroenterogenic cysts are detected in the lower floor of the middle and posterior parts. The most common neoplasms of the posterior mediastinum along its entire length are neurogenic tumors.

Pathogenesis (what happens?) during malignant neoplasms of the anterior mediastinum

Malignant neoplasms of the mediastinum originate from heterogeneous tissues and are united by only one anatomical border. These include not only true tumors, but also cysts and tumor-like formations of different localization, origin and course. All mediastinal neoplasms according to their source of origin can be divided into the following groups:
1. Primary malignant neoplasms of the mediastinum.
2. Secondary malignant tumors of the mediastinum (metastases of malignant tumors of organs located outside the mediastinum to the lymph nodes of the mediastinum).
3. Malignant tumors of the mediastinal organs (esophagus, trachea, pericardium, thoracic lymphatic duct).
4. Malignant tumors from tissues limiting the mediastinum (pleura, sternum, diaphragm).

Symptoms of malignant neoplasms of the anterior mediastinum

Malignant neoplasms of the mediastinum are found mainly in young and middle age (20 - 40 years), equally often in both men and women. During the course of the disease with malignant neoplasms of the mediastinum, an asymptomatic period and a period of pronounced clinical manifestations can be distinguished. Duration asymptomatic period depends on the location and size of the malignant neoplasm, growth rate, relationship with organs and formations of the mediastinum. Very often, mediastinal neoplasms are asymptomatic for a long time, and they are accidentally discovered during a preventive X-ray examination of the chest.

Clinical signs of malignant neoplasms of the mediastinum consist of:
- symptoms of compression or tumor growth into neighboring organs and tissues;
- general manifestations of the disease;
- specific symptoms characteristic of various neoplasms;

The most common symptoms are pain resulting from compression or growth of the tumor into the nerve trunks or nerve plexuses, which is possible with both benign and malignant neoplasms of the mediastinum. The pain is usually mild, localized on the affected side, and often radiates to the shoulder, neck, and interscapular area. Pain with left-sided localization is often similar to pain caused by angina pectoris. If bone pain occurs, the presence of metastases should be assumed. Compression or germination of the borderline sympathetic trunk by a tumor causes the occurrence of a syndrome characterized by drooping of the upper eyelid, dilation of the pupil and retraction of the eyeball on the affected side, impaired sweating, changes in local temperature and dermographism. Damage to the recurrent laryngeal nerve is manifested by hoarseness of voice, the phrenic nerve - by a high standing dome of the diaphragm. Compression of the spinal cord leads to dysfunction of the spinal cord.

A manifestation of compression syndrome is compression of large venous trunks and, first of all, the superior vena cava (superior vena cava syndrome). It is manifested by a violation of the outflow of venous blood from the head and upper half of the body: patients experience noise and heaviness in the head, aggravated in an inclined position, chest pain, shortness of breath, swelling and cyanosis of the face, upper half of the body, swelling of the veins of the neck and chest. Central venous pressure rises to 300-400 mmH2O. Art. When the trachea and large bronchi are compressed, coughing and shortness of breath occur. Compression of the esophagus can cause dysphagia, an obstruction in the passage of food.

In the later stages of development of neoplasms, the following symptoms occur: general weakness, increased body temperature, sweating, weight loss, which are characteristic of malignant tumors. Some patients experience manifestations of disorders associated with intoxication of the body by products secreted by growing tumors. These include arthralgic syndrome, reminiscent of rheumatoid polyarthritis; pain and swelling of the joints, swelling of the soft tissues of the extremities, increased heart rate, irregular heart rhythm.

Some mediastinal tumors have specific symptoms. Thus, skin itching and night sweats are characteristic of malignant lymphomas (lymphogranulomatosis, lymphoreticulosarcoma). A spontaneous decrease in blood sugar levels develops with mediastinal fibrosarcomas. Symptoms of thyrotoxicosis are characteristic of intrathoracic thyrotoxic goiter.

Thus, the clinical signs of neoplasms and mediastinum are very diverse, however, they appear in the late stages of the disease and do not always allow an accurate etiological and topographic-anatomical diagnosis to be established. Data from radiological and instrumental methods are important for diagnosis, especially for recognizing the early stages of the disease.

Neurogenic tumors of the anterior mediastinum are the most common and account for about 30% of all primary mediastinal neoplasms. They arise from nerve sheaths (neurinomas, neurofibromas, neurogenic sarcomas), nerve cells (sympathogoniomas, ganglioneuromas, paragangliomas, chemodectomas). Most often, neurogenic tumors develop from elements of the border trunk and intercostal nerves, rarely from the vagus and phrenic nerves. The usual location of these tumors is the posterior mediastinum. Much less often, neurogenic tumors are located in the anterior and middle mediastinum.

Reticulosarcoma, diffuse and nodular lymphosarcoma(gigantofollicular lymphoma) are also called "malignant lymphomas." These neoplasms are malignant tumors of lymphoreticular tissue, most often affect young and middle-aged people. The tumor initially develops in one or more lymph nodes, followed by spread to neighboring nodes. Generalization occurs early. In addition to the lymph nodes, the metastatic tumor process involves the liver, bone marrow, spleen, skin, lungs and other organs. The disease progresses more slowly in the medullary form of lymphosarcoma (gigantofollicular lymphoma).

Lymphogranulomatosis (Hodgkin's disease) usually has a more benign course than malignant lymphomas. In 15-30% of cases in stage I of the disease, primary local damage to the mediastinal lymph nodes can be observed. The disease is more common between the ages of 20-45 years. The clinical picture is characterized by an irregular wave-like course. Weakness, sweating, periodic rises in body temperature, and chest pain appear. But skin itching, enlargement of the liver and spleen, changes in the blood and bone marrow characteristic of lymphogranulomatosis are often absent at this stage. Primary lymphogranulomatosis of the mediastinum can be asymptomatic for a long time, while enlargement of the mediastinal lymph nodes for a long time may remain the only manifestation of the process.

At mediastinal lymphomas The lymph nodes of the anterior and anterior upper parts of the mediastinum and the roots of the lungs are most often affected.

Differential diagnosis is carried out with primary tuberculosis, sarcoidosis and secondary malignant tumors of the mediastinum. A test of radiation may be helpful in diagnosis, since malignant lymphomas are in most cases sensitive to radiation therapy (the “melting snow” symptom). The final diagnosis is established by morphological examination of the material obtained from a biopsy of the tumor.

Diagnosis of malignant neoplasms of the anterior mediastinum

The main method for diagnosing malignant neoplasms of the mediastinum is x-ray. The use of a comprehensive X-ray examination allows in most cases to determine the localization of the pathological formation - the mediastinum or neighboring organs and tissues (lungs, diaphragm, chest wall) and the extent of the process.

Mandatory X-ray methods for examining a patient with a mediastinal tumor include: - fluoroscopy, radiography and tomography of the chest, contrast examination of the esophagus.

Fluoroscopy makes it possible to identify a “pathological shadow”, get an idea of ​​its location, shape, size, mobility, intensity, contours, and establish the absence or presence of pulsation of its walls. In some cases, one can judge the connection between the identified shadow and nearby organs (heart, aorta, diaphragm). Clarification of the localization of the neoplasm largely makes it possible to predetermine its nature.

To clarify the data obtained during fluoroscopy, radiography is performed. At the same time, the structure of the darkening, its contours, and the relationship of the neoplasm to neighboring organs and tissues are clarified. Contrasting the esophagus helps to assess its condition and determine the degree of displacement or growth of a mediastinal tumor.

Endoscopic research methods are widely used in the diagnosis of mediastinal tumors. Bronchoscopy is used to exclude bronchogenic localization of a tumor or cyst, as well as to determine whether a malignant tumor has invaded the mediastinum of the trachea and large bronchi. During this study, it is possible to perform a transbronchial or transtracheal puncture biopsy of mediastinal formations localized in the area of ​​the tracheal bifurcation. In some cases, mediastinoscopy and videothoracoscopy, in which the biopsy is performed under visual control, turns out to be very informative. Taking material for histological or cytological examination is also possible with transthoracic puncture or aspiration biopsy performed under X-ray control.

If there are enlarged lymph nodes in the supraclavicular areas, they are biopsied, which makes it possible to determine their metastatic lesions or establish a systemic disease (sarcoidosis, lymphogranulomatosis, etc.). If mediastinal goiter is suspected, scanning the neck and chest area after administration of radioactive iodine is used. If compression syndrome is present, central venous pressure is measured.

Patients with mediastinal tumors undergo a general and biochemical blood test, the Wasserman reaction (to exclude the syphilitic nature of the formation), and a reaction with tuberculin antigen. If echinococcosis is suspected, determination of the latexagglutination reaction with echinococcal antigen is indicated. Changes in the morphological composition of peripheral blood are found mainly in malignant tumors (anemia, leukocytosis, lymphopenia, increased ESR), inflammatory and systemic diseases. If systemic diseases are suspected (leukemia, lymphogranulomatosis, reticulosarcomatosis, etc.), as well as immature neurogenic tumors, a bone marrow puncture is performed with the study of a myelogram.

Treatment of malignant neoplasms of the anterior mediastinum

Treatment of malignant neoplasms of the mediastinum- operational. Removal of tumors and mediastinal cysts must be done as early as possible, as this is the prevention of their malignancy or the development of compression syndrome. The only exceptions may be small lipomas and coelomic cysts of the pericardium in the absence of clinical manifestations and a tendency to their increase. Treatment of malignant tumors of the mediastinum in each specific case requires an individual approach. Usually it is based on surgical intervention.

The use of radiation and chemotherapy is indicated for most malignant tumors of the mediastinum, but in each specific case their nature and content are determined by the biological and morphological characteristics of the tumor process and its prevalence. Radiation and chemotherapy are used both in combination with surgical treatment and independently. As a rule, conservative methods form the basis of therapy for advanced stages of the tumor process, when radical surgery is impossible, as well as for mediastinal lymphomas. Surgical treatment for these tumors can be justified only in the early stages of the disease, when the process locally affects a certain group of lymph nodes, which is not so common in practice. In recent years, the videothoracoscopy technique has been proposed and successfully used. This method allows not only to visualize and document mediastinal tumors, but also to remove them using thoracoscopic instruments, causing minimal surgical trauma to patients. The results obtained indicate the high effectiveness of this treatment method and the possibility of carrying out the intervention even in patients with severe concomitant diseases and low functional reserves.

The mediastinum is the area located between the pleural sacs. Bounded laterally by the mediastinal pleura, it extends from the superior thoracic outlet to the diaphragm and from the sternum to the spine. The mediastinum is potentially mobile and is normally held in a midline position due to the equilibrium of pressure in both pleural cavities. In rare cases, openings in the mediastinal pleura cause communication between the pleural sacs. In infants and young children, the mediastinum is extremely mobile; later it becomes more rigid, so that unilateral changes in pressure in the pleural cavity have a correspondingly less effect on it.

Fig.34. Divisions of the mediastinum.

Anatomists divide the mediastinum into 4 sections (Fig. 34). The lower border of the upper mediastinum is a plane drawn through the manubrium of the sternum and the fourth thoracic vertebra. This arbitrary boundary passes below the aortic arch just above the tracheal bifurcation. The anatomical boundaries of other sections are presented in Table 18. Lesions with increased volume in the mediastinum may shift the anatomical boundaries, so that the lesion, which usually occupies its own zone, can spread into others. Changes in the small, congested upper mediastinum are especially prone to cross arbitrary boundaries. However, even normally, some formations extend to more than one part, for example, the thymus gland, extending from the neck through the upper mediastinum to the anterior, the aorta and esophagus, located in both the upper and posterior mediastinum. The anatomical division of the mediastinum is of little clinical significance, but localization of lesions in the mediastinum provides valuable information in establishing the diagnosis (Table 19 and Fig. 35). However, the diagnosis can rarely be established and even less often can benign and malignant lesions be distinguished until accurate histological data are obtained. In 1/5 of cases, mediastinal tumors or cysts may undergo malignant transformation.

Fig.35. Localization of tumors and mediastinal cysts on a lateral radiograph.

The mediastinum is a part of the thoracic cavity located in the midline of the body, which is provided by intrapleural negative pressure. The boundaries of the mediastinum are in front - the sternum and the cartilages of the ribs attached to it, behind - the thoracic spine and neck of the ribs, on the sides - the mediastinal pleura, below - the diaphragm. At the top, the mediastinum passes without definite boundaries into the cellular spaces of the neck. The proximal border of the mediastinum is a line drawn along the upper edge of the manubrium. The dimensions of the mediastinum (depth and width) are not the same. The greatest width of the mediastinum is in the lower section, the depth is between the spine and the xiphoid process. The smallest width is in the middle part, the depth is between the manubrium of the sternum and the spine.

Anatomically, the mediastinum is a single space, but based on practical considerations, four sections are distinguished.

By a conditional horizontal plane passing through the area of ​​​​the connection of the manubrium and the body of the sternum towards the IV vertebra, the mediastinum is divided into upper and lower. The lower mediastinum is divided by the pericardium into anterior, middle and posterior. The anterior lower mediastinum is located between the sternum and the pericardium, the middle one is limited by the pericardium. The boundaries of the posterior mediastinum are the bifurcation of the trachea and the pericardium in front, and the lower thoracic spine in the back.

In the upper mediastinum there are the proximal parts of the trachea, esophagus, thymus, aortic arch and its branches, thoracic lymphatic duct, brachiocephalic veins. The anterior mediastinum contains adipose tissue, lymph nodes, and the distal thymus gland. The middle mediastinum contains the heart, pulmonary arteries and veins, tracheal bifurcation, main bronchi, and lymph nodes. The posterior mediastinum includes the esophagus, descending aorta, thoracic lymphatic duct, sympathetic and parasympathetic nerves.

In addition to the above, it has been proposed to divide the mediastinum only into anterior and posterior sections. The boundary between them is the conventional frontal plane passing through the root of the lung.

All anatomical formations of the mediastinum are surrounded by loose fatty tissue, separated by fascial sheets. On the lateral surface it is covered by the pleura. Most fiber is found in the posterior mediastinum, less - between the pleura and pericardium.

An important organ of the upper mediastinum is the thymus gland (thymus), which has the shape of a pyramid and consists of two lobes. The gland is well developed in children under 2 years of age. In children, the thymus is divided into the thoracic and cervical parts, which protrude 1.5 - 2 cm above the manubrium of the sternum. Its lower edge corresponds to the level of the III - V ribs. In adults, the cervical spine is absent.

The thymus gland occupies an intrathoracic position. The lower pole of the thymus is localized at the level of the third rib, and the upper pole is located behind the manubrium of the sternum. The anterior surface of the gland is in contact with the sternum, the posterior surface is in contact with the superior vena cava, brachiocephalic trunk and innominate veins. The lower surface of the thymus is adjacent to the pericardium, the anterior outer surface is adjacent to the pleura. The gland is surrounded by a connective tissue capsule with septa extending inward from it. The latter divide the thymus into lobules. Each lobule consists of a cortex and medulla. The cortex has an adenoid structure with scattered T-lymphocytes. The structure of the medulla is similar to the structure of the cortex, but it contains fewer lymphocytes. The mass of the thymus gland depends on the constitution and degree of fatness of people.

Mediastinum. Anatomy.

The mediastinum, mediastinum, is a part of the chest cavity, delimited above by the superior thoracic opening, below by the diaphragm, in front by the sternum, behind by the spinal column, and on the sides by the mediastinal pleura.

The mediastinum is divided into: anterior, middle and posterior mediastinum.

The border between the anterior and middle mediastinum is the frontal plane drawn along the anterior wall of the trachea; the border between the middle and posterior mediastinum passes at the level of the posterior surface of the trachea and the roots of the lungs in a plane close to the frontal.

In the anterior and middle mediastinum are located: the heart and pericardium, the ascending aorta and its arch with branches, the pulmonary trunk and its branches, the superior vena cava and brachiocephalic veins; trachea, bronchi with surrounding lymph nodes; bronchial arteries and veins, pulmonary veins; the thoracic part of the vagus nerves, lying above the level of the roots; phrenic nerves, lymph nodes; in children, the thymus gland, and in adults, the adipose tissue that replaces it.

In the posterior mediastinum are located: the esophagus, descending aorta, inferior vena cava, azygos and semi-gypsy veins, thoracic lymphatic duct and lymph nodes; the thoracic part of the vagus nerves, lying below the roots of the lungs; borderline sympathetic trunk along with splanchnic nerves, nerve plexuses.

In addition, a conditionally drawn horizontal plane passing at the level of the bifurcation of the trachea, the mediastinum is divided into upper and lower.

X-ray anatomical analysis.

Direct projection.

When examined in direct projection, the organs of the mediastinum form an intense, so-called median shadow, represented mainly by the heart and large vessels, which projection overlap the remaining organs.

The outer contours of the mediastinal shadow are clearly demarcated from the lungs; they are more convex at the level of the edge-forming contours of the heart and are more straightened in the area of ​​the vascular bundle, especially on the right with the edge-forming location of the superior vena cava.

The upper part of the mediastinum looks less intense and homogeneous, since the trachea is projected in the middle, forming a longitudinally located light strip, about 1.5 - 2 cm wide.

The lymph nodes of the mediastinum normally do not provide a differentiated image and are visible only with enlargement, calcification or contrast.

The shape and size of the median shadow are variable and depend on the age, constitution, breathing phase and position of the subject.

When breathing, the median shadow, changing its transverse size, does not make noticeable lateral displacements. Lateral jerky displacement of the median shadow during fast and deep inspiration is one of the signs of impaired bronchial conduction.

Lateral projection.

The anterior mediastinum in the x-ray image is projected between the posterior surface of the sternum and the vertical line drawn along the anterior wall of the trachea. In the upper part of it in adults, the shadow of the ascending aorta is visible, the anterior contour of which bulges somewhat anteriorly, is clearly defined, directed upward and posteriorly passes into the shadow of the aortic arch. In children, the thymus gland is located anterior to the ascending aotra. The triangular-shaped area of ​​clearing, delimited in front by the sternum, below by the heart, and behind by the ascending aorta, is called the retrosternal space. The high transparency of the retrosternal space should be taken into account when recognizing pathological processes of the anterior mediastinum, since even massive pathological formations (enlarged prevascular lymph nodes, tumors and mediastinal cysts) can produce shadows of low intensity as a result of the “weakening” effect of the projected air lung tissue.

The lower part of the anterior mediastinum is occupied by the shadow of the heart, against which the vessels of the middle lobe and lingular segments are projected.

The middle mediastinum in the upper section has a heterogeneous structure, due to a clear image of the air column of the trachea, down from which the shadows of the roots of the lungs are projected onto the mediastinum. The lower middle mediastinum is also occupied by the heart. The shadow of the inferior vena cava is visible in the posterior cardiophrenic angle.

The posterior mediastinum is projected between the posterior wall of the trachea and the anterior surface of the thoracic vertebral bodies. In the X-ray image, it has the appearance of a longitudinally located strip of clearing, against which in elderly people a vertically located shadow of the descending aorta about 2.5 - 3 cm wide is visible. The upper part of the posterior mediastinum is covered by the muscles of the upper shoulder girdle and shoulder blades, due to which it has reduced transparency. The lower part of the posterior mediastinum, delimited by the heart, diaphragm and vertebrae, has greater transparency and is called the retrocardial space. The vessels of the main segments of the lungs are projected against its background.

Normally, the transparency of the retrosternal and retrocardial spaces in its lower part is almost the same.

Twining proposed an even more detailed division of the mediastinum into 9 parts. The border between the anterior and middle mediastinum is drawn along a vertical line connecting the sternoclavicular joint and the anterior part of the diaphragm at the place of its projection intersection with the pleura of the oblique fissure. The posterior mediastinum is separated from the middle frontal plane, passing slightly posterior to the trachea. The dividing line between the upper and middle mediastinum runs in a horizontal plane at the level of the body of the V thoracic vertebra, and between the middle and lower - in a horizontal plane, drawn at the level of the body of the VIII or IX thoracic vertebra.

The heart, pericardium and large vessels (aorta, pulmonary trunk, superior vena cava and inferior vena cava) in the X-ray image represent a single complex called the vascular bundle.

Direct anterior projection. The heart and large vessels form an intense and homogeneous shadow, which is located asymmetrically with respect to the median plane. 2/3 of it is on the left, and 1/3 is on the right. There are right and left contours of the cardiovascular shadow.

Along the right contour, as a rule, two arcs are differentiated. The superior arch is formed by the superior vena cava and partially the ascending aorta, the lower by the right atrium. The azygos vein is projected slightly to the right of the midline, arr. round or oval shadow. Along the left contour of the s.s. the shadows are distinguished by four edge-forming arcs. Consistently from top to bottom: arc and beginning. section of the descending aorta, pulmonary trunk in the place from the beginning. section of the left pulmonary artery arr. second arch, the left ear is edge-forming in 30% of cases, the left ventricle arr. fourth arc.

Diseases that are accompanied by damage to the intrathoracic lymph nodes

The X-ray picture in pathological conditions of the intrathoracic lymph nodes generally reflects pathomorphological changes in the region of the lung root, which are often manifested by expansion of the roots and deconfiguration of the median shadow.

Research methods.

1. Polypositional fluoroscopy and polyprojection radiography.

2. Tomography in direct, lateral and oblique projections. Computed tomography.

3. Contrasting of the esophagus.

4.Pneumomediastinography.

5.Bronchography and bronchological examination.

6. Biopsy of peripheral lymph nodes.

7. Mediastinoscopy with biopsy.

X-ray anatomy of the lung root.

X-ray examination of the root of the lung distinguishes between the head (arch of the pulmonary artery and the vessels extending from it) and the body (trunk of the pulmonary artery). Inward from it is the intermediate bronchus, which separates the artery from the median shadow. Arterial vessels extending from the trunk and venous vessels (superior and sometimes inferior pulmonary vein) also participate in the formation of this part of the root. Distal to the body is the caudal part of the root (proximal segments of the terminal branches of the pulmonary arteries that supply blood to the lower zones and lower pulmonary veins). The diameter of the root at the level of the body should not exceed 2.5 cm. It is measured from the edge of the median shadow to the outer contour of the pulmonary artery. The outer contour of the lung root is normally straight or slightly concave. Normally, the root is structural. The described objective criteria make it possible to distinguish a normal lung root from a pathologically altered one.

Tuberculous bronchadenitis

Tuberculosis of the intrathoracic lymph nodes of the root of the lung and mediastinum can be an integral part of the primary tuberculosis complex - primary or be involved in the process secondary.

The lymphatic nodes of the tracheobronchial group are primarily affected; in 2/3 of cases on the right. The next most common lesion is the bronchopulmonary group of lymph nodes of the lung root on the right; less often, the lymph nodes of the bifurcation group are involved in the process.

The X-ray picture is quite demonstrative. On a plain radiograph, the shadow of the affected lymph node creates a picture of a unilateral expansion of the median shadow. On tomograms in frontal and lateral projections made in the plane of the lung root, the shadow of the affected lymph nodes is superimposed on the image of the air column of the trachea or bronchus. With an isolated lesion of a single lymph node, a single oval shadow measuring from 1x2 to 3x4 cm is detected. The outer contours of the shadow are more or less clear and even. The structure of the shadow is heterogeneous due to inclusions of lime, which are small in size and located eccentrically, closer to the capsule. Calcification detected on plain and layered radiographs is the most characteristic symptom of tuberculous bronchadenitis and occurs with a frequency of about 54% (Rozenshtraukh L.S., Winner M.G.). A typical variant of radiological manifestations of tuberculous bronchadenitis includes observations when, along with enlargement of the lymph nodes of the root of the lung, tuberculous changes were also detected in the lung tissue in the form of infiltrate or tuberculoma. In this case, tuberculous infiltrate or tuberculoma in patients with typical manifestations is located on the side of the lymph nodes affected by tuberculosis and is accompanied by pronounced symptoms of lymphangitis in the form of a path to the root. This combination of changes in the lungs corresponds to the classic form of the primary tuberculosis complex. Enlarged lymph nodes are not calcified; the bronchopulmonary group is mainly affected.