Topography of mediastinal organs. Posterior mediastinum (mediastinum posterior) Structure of the human mediastinum

MEDIASTINUM, mediastinum, plural. no, cf. 1. The space between the spine and the sternum, in which the heart, aorta, bronchi and other organs are located (anat.). 2. transfer A barrier, an obstacle that prevents communication between two parties (book). “...Abolish... ... Ushakov's Explanatory Dictionary

MEDIASTINUM- MEDIASTINUM, mediastinum (from Latin in me dio stans standing in the middle), the space located between the right and left pleural cavities and limited laterally by the pleura mediastinalis, dorsally by the thoracic spine by the ischs of the ribs... Great Medical Encyclopedia

Mediastinum- (anatomical), part of the chest cavity in mammals and humans, in which the heart, trachea and esophagus are located. In humans, the mediastinum is limited on the sides by the pleural sacs (they contain the lungs), below by the diaphragm, in front by the sternum, behind... ... Illustrated Encyclopedic Dictionary

MEDIA, I, cf. (specialist.). The place in the middle part of the chest cavity where the heart, trachea, esophagus, and nerve trunks are located. | adj. mediastinal, oh, oh. Ozhegov's explanatory dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 … Ozhegov's Explanatory Dictionary

- (mediastinum), the middle part of the thoracic cavity of mammals, which contains the heart with large vessels, trachea and esophagus. Bounded anteriorly by the sternum, posteriorly by the thoracic spine, laterally by the pleura, and inferiorly by the diaphragm; top, considered the border... Biological encyclopedic dictionary Publisher: Publishing Solutions, eBook(fb2, fb3, epub, mobi, pdf, html, pdb, lit, doc, rtf, txt)

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 posterior mediastinum includes the organs located behind the respiratory tube (Fig. 120, 121). It contains the esophagus, descending aorta, azygos and semi-gypsy veins, the lower portion of the vagus nerves and the thoracic lymphatic duct.

Rice. 120. Topography of mediastinal organs on horizontal cuts.
1 - truncus sympathicus; 2 - pleural fissure; 3 - thoracic lymphatic duct; 4 - a. subclavia sinistra; 5 - n. vagus; 6 - a. carotis communis sinistra; 7 - n. phrenicus; S-v. brachiocephalica sinistra; 9 - collarbone; 10 - sternum; 11 - truncus brachiocephalicus; 12 - v. brachiocephalica dextra; 13 - trachea, - 14 - esophagus; 15 - aortic arch; 16 - cavity of the cardiac membrane; 17 - v. cava superior; 18 -v. azygos; 19 - descending aorta; 20 - aorta with its valves; 21 - right ventricle; 22 - right atrium; 23 - left atrium with pulmonary vein.

Rice. 121. Topography of the organs of the posterior mediastinum.
1 - a. carotis communis; 2 - esophagus; 3 - n. recurrent; 4 - n. vagus; 5 - a. subclavia; 6 - aortic arch; 7 - fork of the trachea; 8 - thoracic aorta; 9 - abdominal esophagus; 10 - a. coeliaca; 11 - diaphragm; 12 - lymph nodes; 13 - 1st rib; - trachea; 15 - larynx; 16 - v. azygos; 17 - thoracic lymphatic duct.

Esophagus(oesophagus) begins at the VI cervical vertebra and ends at the XI-XII thoracic vertebra. The thoracic region includes the section of the organ from the I to XI thoracic vertebrae, the length of the thoracic region is 16-20 cm. The esophagus forms bends. The upper, or left, bend follows to the third thoracic vertebra; at the height of the IV vertebra, it occupies a median position and then deviates to the right, so that at the level of the X thoracic vertebra it again shifts to the left. In the thoracic cavity, the esophagus has two narrowings: the middle (the upper one was at the beginning of the cervical region), or thoracic, with a diameter of 14 mm, at the height of the IV thoracic vertebra, which corresponds to the level of the aortic arch, and the lower, or diaphragmatic, corresponding to the hole in the diaphragm. (XI thoracic vertebra), diameter 12 mm. The esophagus lies on the spine behind the trachea, but at the level of the IV thoracic vertebra, going down, it gradually slopes forward, and at the diaphragm, slightly to the left. As a result of this, the esophagus changes position in relation to the descending aorta: at first it lies to the right of it, and then it turns out to be located in front. Below the bifurcation of the trachea in front of the esophagus are the posterior wall of the left atrium and below the pericardium, which limits the oblique sinus of the chamber of the heart. On the left, above the descending aorta, its arch and subclavian artery are adjacent to the esophagus. The pleura of the mediastinum adjoins it on the right. Moreover, in some cases it can extend into the back surface of the esophagus in the form of pockets, both in its upper and lower sections. Behind the esophagus is the thoracic lymphatic duct, in the middle section of the mediastinum on the right it extends behind the azygos vein and in the lower section on the left - the aorta.

The thoracic esophagus is supplied with blood from the branches of the descending aorta, bronchial and intercostal arteries. Venous outflow occurs through the thyroid, azygos, semi-gypsy veins into the superior vena cava and through the gastric veins into the portal vein system. Lymphatic pathways drain lymph to the nodes: deep cervical, subclavian, tracheal, bifurcation of the trachea, posterior mediastinum, nodes of the stomach and celiac artery. The esophagus is innervated by branches of the sympathetic nerves and vagus nerves.

Azygos and semi-azygos veins(vv. azygos et hemiazygos) are a continuation of the ascending lumbar veins running through the diaphragm between its internal and intermediate legs.

The azygos vein follows to the right of the esophagus (it can go beyond it at the height of the VI-IX thoracic vertebrae), at the level of the IV thoracic vertebra it bends through the right bronchus and flows into the superior vena cava. It receives 9 intercostal veins, veins of the mediastinum, bronchi and esophagus. The semi-zygos vein passes along the anterior-left surface of the vertebral bodies; at the height of the VIII thoracic vertebra it turns to the right and, passing behind the esophagus, joins the azygos vein. From the upper parts of the mediastinum, an accessory vein flows into the hemizygos vein. The intercostal veins of the corresponding side flow into these veins. The azygos vein is an anastomosis between the superior and inferior vena cava, which is important for congestion of the inferior vena cava. The azygos vein is also connected to the portal vein system through the gastric veins and esophageal veins.

Thoracic lymphatic duct(ductus thoracicus) begins at the level of the I-II lumbar vertebrae, where in half of the cases there is an extension (cisterna chyli), into which two lumbar lymphatic trunks and vessels from the intestines flow. In the mediastinum, the trunk passes through the aortic opening in the diaphragm and is located here behind and slightly to the right of the aorta, fused with the right leg of the diaphragm; contraction of the leg during movements of the diaphragm promotes the movement of lymph along the duct. In the mediastinum, it “follows between the azygos vein and the descending aorta, covered in front by the esophagus. At the height of the V thoracic vertebra, the duct gradually deviates to the left from the midline of the body and follows to the confluence of the left jugular and subclavian veins. At first it is closer to the right pleura, and in the upper sections - to the left pleura. This explains the formation of chylothorax (effusion of lymph into the pleural cavity) on the right side when the thoracic duct is injured in the lower parts of the mediastinum and on the left side when there is damage in its upper parts. The intercostal lymphatic vessels and the bronchomediastinal trunk, which collects lymph from the organs of the left half of the thoracic cavity, flow into the thoracic duct.

Thoracic descending aorta(aorta descendens) 16-20 cm long stretches from the IV to the XII thoracic vertebra, where, penetrating the diaphragm, it goes into the abdominal cavity. 9-10 pairs of intercostal arteries (aa. intercostales) depart from its posterior surface, and from the anterior surface - the superior phrenic arteries (aa. phrenicae superiores), bronchial, esophageal, arteries of the cardiac sac and mediastinum. The descending aorta borders: in the upper, front section with the left bronchus and the cardiac sac, on the right with the esophagus and thoracic duct, on the left with the pleura of the mediastinum and behind with the hemizygos vein and the spine; in the lower part in front and with the esophagus, on the right - with the azygos vein and pleura of the mediastinum, on the left - with the pleura of the mediastinum and behind - with the thoracic duct and spine.

Vagus nerves(nn. vagi) of the right and left sides have an independent topography. The right nerve, passing between the subclavian vessels, enters the chest cavity. Having passed in front of the subclavian artery, it gives off a recurrent branch under it, which returns to the neck. Next, the vagus nerve follows the right bronchus, and, approaching the esophagus at the level of the V thoracic vertebra, is located on its posterior surface. The left vagus nerve passes from the neck into the chest cavity between the common carotid and subclavian arteries, then crosses the aortic arch in front, enters the left bronchus and then from the level of the VIII thoracic vertebra follows along the anterior surface of the esophagus. Having passed the aortic arch, it gives off the left recurrent nerve, which, after going around the arch from below and behind, rises to the neck along the left tracheoesophageal groove. Within the mediastinum, the following branches depart from the vagus nerves: anterior and posterior bronchial, esophageal, cardiac shirts.

Sympathetic trunks(trunci sympatici) as a continuation of the cervical trunks in the thoracic cavity are located on the sides of the vertebral bodies, corresponding to the heads of the ribs. Within the mediastinum they have 10-11 nodes. From each node to the intercostal nerves there are branches connecting the sympathetic nervous system with the animal one - rami communicantes. From V-IX thoracic nodes, large splanchnic nerves (n. splanchnici major) are formed, from X-XI thoracic nodes - small splanchnic nerves (n. splanchnici minoris) and from XII thoracic nodes - unpaired or third splanchnic nerves (n. splanchnici imus , s. tertius). All these nerves, passing through the holes in the diaphragm, form nerve plexuses in the abdominal cavity. The first forms the solar plexuses, the second - the solar and renal plexuses, and the third - the renal plexuses. In addition, small branches extend from the border trunks to the nerve plexuses of the aorta, esophagus, and lungs.

• 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 a collection of organs, nerves, lymph nodes and vessels that are located in the same space. In front it is limited by the sternum, on the sides by the pleura (the membrane surrounding the lungs), and behind by the thoracic spine. Below, the mediastinum is separated from the abdominal cavity by the largest respiratory muscle - the diaphragm. There is no border at the top; the chest smoothly passes into the space of the neck.

Classification

For greater convenience in studying the organs of the chest, its entire space was divided into two large parts:

• anterior mediastinum;

The front, in turn, is divided into upper and lower. The border between them is the base of the heart.

Also in the mediastinum there are spaces filled with fatty tissue. They are located between the sheaths of blood vessels and organs. These include:

• retrosternal or retrotracheal (superficial and deep) - between the sternum and esophagus;
• pretracheal - between the trachea and the aortic arch;
• left and right tracheobronchial.

Boundaries and main organs

The boundary of the posterior mediastinum is the pericardium and trachea in front, and the anterior surface of the thoracic vertebral bodies in the back.

The following organs are located within the anterior mediastinum:

• the heart with a sac surrounding it (pericardium);
• upper respiratory tract: trachea and bronchi;
• thymus gland or thymus;
• phrenic nerve;
• the initial part of the vagus nerves;
• two sections of the largest vessel of the body - the part and the arch).

The posterior mediastinum includes the following organs:

• the descending part of the aorta and the vessels extending from it;
• the upper part of the gastrointestinal tract is the esophagus;
• part of the vagus nerves located below the roots of the lungs;
• thoracic lymphatic duct;
• azygos vein;
• hemizygos vein;
• abdominal nerves.

Features and anomalies of the structure of the esophagus

The esophagus is one of the largest organs of the mediastinum, namely its posterior part. Its upper border corresponds to the VI thoracic vertebra, and the lower border corresponds to the XI thoracic vertebra. This is a tubular organ that has a wall consisting of three layers:

• mucous membrane inside;
• muscle layer with circular and longitudinal fibers in the middle;
• serous membrane from the outside.

The esophagus is divided into cervical, thoracic and abdominal parts. The longest of them is the chest. Its dimensions are approximately 20 cm. At the same time, the cervical region is about 4 cm long, and the abdominal region is only 1-1.5 cm.

Among the malformations of the organ, the most common is esophageal atresia. This is a condition in which the named part of the digestive canal does not pass into the stomach, but ends blindly. Sometimes, with atresia, a connection is formed between the esophagus and the trachea, which is called a fistula.

It is possible to form fistulas without atresia. These passages can occur with the respiratory organs, pleural cavity, mediastinum, and even directly with the surrounding space. In addition to congenital etiology, fistulas form after injuries, surgical interventions, cancer and infectious processes.

Features of the structure of the descending aorta

When considering the anatomy of the chest, you should look at the largest vessel in the body. In the posterior part of the mediastinum is its descending section. This is the third part of the aorta.

The entire vessel is divided into two large sections: thoracic and abdominal. The first of them is located in the mediastinum from the IV thoracic vertebra to the XII. To the right of it is the azygos vein and on the left side is the semi-gypsy vein, in front is the bronchus and the cardiac sac.

It gives two groups of branches to the internal organs and tissues of the body: visceral and parietal. The second group includes 20 intercostal arteries, 10 on each side. Internal ones, in turn, include:

• - most often there are 3 of them, which carry blood to the bronchi and lungs;
• esophageal arteries - there are from 4 to 7 of them, supplying blood to the esophagus;
• vessels supplying blood to the pericardium;
• mediastinal branches - carry blood to the lymph nodes of the mediastinum and fatty tissue.

Features of the structure of the azygos and semi-gypsy vein

The azygos vein is a continuation of the right ascending lumbar artery. It enters the posterior mediastinum between the legs of the main respiratory organ - the diaphragm. There, on the left side of the vein, there is the aorta, spine and thoracic lymphatic duct. 9 intercostal veins flow into it on the right side, bronchial and esophageal veins. A continuation of the azygos is the inferior vena cava, which carries blood from the whole body directly to the heart. This transition is located at the level of the IV-V thoracic vertebrae.

The hemizygos vein is also formed from the ascending lumbar artery, only located on the left. In the mediastinum it is located behind the aorta. Then she approaches the left side of the spine. Almost all intercostal veins on the left flow into it.

Features of the structure of the thoracic duct

When considering the anatomy of the chest, it is worth mentioning the thoracic part of the lymphatic duct. This section originates in the aortic opening of the diaphragm. And it ends at the level of the upper thoracic aperture. First, the duct is covered by the aorta, then by the wall of the esophagus. Intercostal lymphatic vessels flow into it from both sides, which carry lymph from the back of the chest cavity. It also includes the bronchomediastinal trunk, which collects lymph from the left side of the chest.

At the level of the II-V thoracic vertebrae, the lymphatic duct sharply turns to the left and then approaches the VII vertebra of the cervical spine. On average, its length is 40 cm, and the width of the lumen is 0.5-1.5 cm.

There are different options for the structure of the thoracic duct: with one or two trunks, with a single trunk that bifurcates, straight or with loops.

Blood enters the duct through the intercostal vessels and esophageal arteries.

Features of the structure of the vagus nerves

The left and right vagus nerves of the posterior mediastinum are distinguished. The left nerve trunk enters the space of the chest between two arteries: the left subclavian and the common carotid. The left recurrent nerve departs from it, bending around the aorta and tending to the neck area. Further, the vagus nerve goes behind the left bronchus, and even lower - in front of the esophagus.

The right vagus nerve is first placed between the subclavian artery and vein. The right recurrent nerve departs from it, which, like the left, approaches the space of the neck.

The thoracic nerve gives off four main branches:

• anterior bronchial - part of the anterior pulmonary plexus along with the branches of the sympathetic trunk;
• posterior bronchial - are part of the posterior pulmonary plexus;
• to the cardiac sac - small branches carry a nerve impulse to the pericardium;
• esophageal - form the anterior and posterior esophageal plexuses.

Mediastinal lymph nodes

All lymph nodes located in this space are divided into two systems: parietal and visceral.

The visceral system of lymph nodes includes the following formations:

• anterior lymph nodes: right and left anterior mediastinal, transverse;
• posterior mediastinal;
• tracheobronchial.

When studying what is in the posterior mediastinum, it is necessary to pay special attention to the lymph nodes. Since the presence of changes in them is a characteristic sign of an infectious or cancerous process. Generalized enlargement is called lymphadenopathy. It can occur for a long time without any symptoms. But prolonged enlargement of the lymph nodes eventually makes itself felt with the following disorders:

• loss of body weight;
• lack of appetite;
• increased sweating;
• high body temperature;
• sore throat or pharyngitis;
• enlarged liver and spleen.

Not only medical workers, but also ordinary people should have an idea of ​​the structure of the posterior mediastinum and the organs that are located in it. After all, this is a very important anatomical formation. Violation of its structure can lead to serious consequences requiring the help of a specialist.