What organs are located in the mediastinum? Mediastinal tumors: types, symptoms, modern methods of treatment. Features of the structure of the vagus nerves


TOPOGRAPHY OF THE MEDIASTINUM ORGANS

Purpose of the present teaching aid- outline the relative position of the organs of the thoracic cavity, highlight topographical features that are of interest for making a clinical diagnosis, and also give an idea of ​​the main surgical interventions on the mediastinal organs.

MEDIA - part chest cavity, located between the thoracic vertebrae behind, the sternum in front and two layers of the mediastinal pleura laterally. The mediastinum is bounded above by the superior thoracic aperture and below by the diaphragm. The volume and shape of this space changes during breathing and due to the contraction of the heart.

In order to facilitate the description of the relative positions of individual organs in various departments The mediastinum is usually divided into parts. Moreover, due to the fact that there are no objective anatomical and physiological boundaries between these parts, this is done differently in different literary sources.

In some textbooks on systemic and topographic anatomy, two mediastinums are distinguished: anterior and posterior. The boundary between them is the frontal plane drawn through the root of the lung.

In textbooks on surgery you can find a division of the mediastinum into right and left. It is emphasized that predominantly venous vessels are adjacent to the right mediastinal pleura, and arterial vessels are adjacent to the left.

Recently, in the anatomical and clinical literature, the most common description of the organs of the thoracic cavity in connection with the upper and lower mediastinum; last, c. in turn, is divided into anterior, middle and posterior. This division is in accordance with the international anatomical nomenclature of the latest revision and forms the basis for the presentation of the material in this methodological manual.

UPPER SEDUS (mediastinum superior) - a space located between two layers of the mediastinal pleura and bounded above by the upper aperture of the chest, below by a plane drawn between the angle of the sternum and the lower edge of the fourth thoracic vertebra.

The key structure of the upper mediastinum is the aortic arch (arcus aonae). It begins at the level of the second right sternocostal joint, rises upward by about 1 cm, bends in an arc to the left side and descends to the level of the Fourth thoracic vertebra, where it continues into the descending part aorta. Three large vessels begin from the convex side of the aortic arch (Fig. 1,2).

1. Brachiocephalic trunk (truncus brachiocephalicus) - departs at the level of the upper edge of the cartilage of the second rib and rises to the right sternoclavicular joint, where it divides into the right common carotid and subclavian arteries.

2. Left common carotid artery (a.carotis communis sinistra) - originates to the left of the brachiocephalic trunk, goes to the left sternoclavicular joint and then continues to the neck.

3. Left subclavian artery (a.subclavia sinistra) - from its origin, through the upper aperture of the cell, it exits to the neck.

The following structures are located in front and to the right of the aortic arch:

The thymus gland (tymus), which consists of two lobes and is separated from the manubrium of the sternum by the retrosternal fascia. The gland reaches its maximum size in children and then undergoes involution. In some cases upper limit the thymus can pass on the neck, the lower one - in the anterior mediastinum;

Brachiocephalic veins (vv. brachiocephalicae) - lie behind the thymus gland. These vessels are formed in the lower neck as a result of the confluence of the internal jugular and subclavian veins. The left brachiocephalic vein is three times longer than the right and crosses the superior mediastinum from top to bottom, from left to right. At the right edge of the sternum, at the level of the cartilage of the first rib, the brachiocephalic veins merge, resulting in the formation of the upper vena cava;

Superior vena cava (v. cava superior) - descends along the right edge of the sternum to the second intercostal space, where it enters the pericardial cavity;

Right phrenic nerve (n. phrenicus dexter) - enters the upper mediastinum between the right subclavian vein and artery, descends along the lateral surface of the brachiocephalic and superior vena cava, and then lies in front of the root of the lung;

Brachiocephalic The lymph nodes(nodi lymphatici brachiocephalici) - located in front of the veins of the same name, collect lymph from the thymus and thyroid glands, the pericardium.

In front and to the left of the aortic arch are located:

The left superior intercostal vein (v. intercostalis superior sinistra), collects blood from the upper three intercostal spaces and flows into the left brachiocephalic vein;

Left phrenic nerve (n. phrenicus sinister) - enters the upper mediastinum in the interval between the left common carotid and subclavian arteries, crosses the left brachiocephalic vein from behind, and then lies in front lung root;

The left vagus nerve (n.vagus sinister) is adjacent to the aortic arch and intersects with the phrenic nerve, located behind it.

Behind the aortic arch are located: - trachea - runs in a vertical direction, deviating slightly to the right from the midline. At the level of the fourth thoracic vertebra, the trachea divides into two main bronchi;

The esophagus (oesophageus) is in direct contact with the right mediastinal pleura, located posterior to the trachea and in front of the vertebral bodies, from which it is separated by the prevertebral fascia and intrathoracic fascia;

The right vagus nerve (n. vagus dexter) - enters the upper mediastinum in front of the subclavian artery, at the lower edge of which the right recurrent laryngeal nerve originates from the i-th. Then the n.vagus behind the brachial vein approaches the lateral wall of the trachea, along which it goes to the root of the lung;

Left return laryngeal nerve(p. laryngeus recarrens sinister) - starts from the vagus nerve, first bends around the aortic arch from below, and then rises to the neck in the groove between the trachea and esophagus. Irritation of the laryngeal nerve with an aneurysm of the aortic arch or with syphilitic damage to its wall explains the presence in such patients of hoarseness and a long-lasting dry cough. Similar symptoms can also be observed with lung cancer due to irritation of the nerve by enlarged lymph nodes.

Thoracic duct (ductus thoracius) - passes to the left of the esophagus and flows into the left one in the neck area venous angle(the junction of the internal jugular and subclavian veins);

Paratracheal lymph nodes (nodi lymphatici paratracheales) - located around the trachea and collect lymph from the upper and lower tracheobronchial lymph nodes.

ANTERIOR MEDIASTINUM (mediastinum anterior) - located anterior to the pericardium and limited above by a plane connecting the angle of the sternum with the lower edge of the body of the fourth thoracic vertebra, below by the diaphragm, in front by the sternum. In addition to loose fiber, it contains:

Perirudinal lymph nodes (nodi lymphatici parasternales) – located along the course of a. thoracica interna and collecting lymph from the mammary gland (medial lower quadrant), the upper third of the anterolateral abdominal wall, deep structures anterior chest wall and upper surface of the liver;

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superior diaphragmatic lymph nodes (nodi lymphatici superiores) - are located at the base of the xiphoid process and collect lymph from the upper surface of the liver and the anterior part of the diaphragm.

WITH
MEDIASTINUM (mediastinum medium) - includes the pericardium, right and left phrenic nerves, pericardial diaphragmatic arteries and veins.

Pericardium (pericardium) - consists of two layers: the outer - fibrous (pericardium fibrosum) and the inner - serous (pericardium serosum). In turn, the serous pericardium is divided into two plates: the parietal plate, lining the fibrous pericardium from the inside, and the visceral plate, covering the vessels and heart (epicardium). The free space between the two plates of the pericardium serosum is called the pericardial cavity and is normally filled with a small amount of serous fluid.

The pericardium contains the following structures.

The heart (cor), which is projected onto the anterior surface of the chest between four points located: the first - at the level of the cartilage of the right third rib, 1 - 1.5 centimeters from the edge of the sternum; the second - at the level of the cartilage of the left third rib, 2 - 2.5 centimeters from the edge of the sternum; the third - at the level of the right sixth sternocostal joint and the fourth - in the fifth intercostal space at a distance of 1 - 1.5 centimeters inward from the left midclavicular line.

The ascending part of the aorta (pars ascendens aortae) - starts from the left ventricle at the level of the cartilage of the third rib to the left of the sternum, rises up to the cartilage of the second rib, where, after leaving the pericardial cavity, it continues into the aortic arch (Fig. 3).

The lower segment of the superior vena cava, which, after entering the pericardium at the level of the 2nd intercostal space, ends in the right atrium.

Pulmonary trunk (truncus pulmonalis) - starts from the right ventricle and goes from right to left, from front to back. In this case, the trunk is located first ventrally, and then slightly to the left of the ascending aorta. Outside the pericardium, downward from the aortic arch, there is a bifurcation of the pulmonary trunk (bifurcatio trunci pulmonalis). The pulmonary arteries starting in this place are directed to the gates of the lung. In this case, the left pulmonary artery passes in front of the descending aorta, the right - behind the superior vena cava and the ascending aorta. The bifurcation of the pulmonary trunk is connected to the lower surface of the aortic arch with the help of the arterial ligament, which in the fetus is a functioning vessel - the arterial (botal) duct.

Pulmonary veins (vv. pulmonales) - enter the pericardial cavity shortly after leaving the hilum of the lung and end in the left atrium. In this case, two right pulmonary veins pass posterior to the superior vena cava, and two left ones pass ventrally to the descending aorta.

The phrenic nerves in the middle mediastinum pass respectively between the right and left mediostinal pleura on one side and the pericardium on the other. The nerves accompany the pericardial phrenic vessels. Arteries are branches of the internal thoracic arteries, veins are tributaries w. ihoracicae, internae. In accordance with the international anatomical nomenclature, two sinuses are distinguished in the pericardial cavity:

Transverse (sinus transversus), limited anteriorly by the aorta and pulmonary trunk, posteriorly by the left atrium, right pulmonary artery and superior vena cava (Fig. 4);

Oblique (sinus obliquus), limited anteriorly by the left atrium, posteriorly by the parietal plate of the serous pericardium, above and to the left by the left pulmonary veins, below and to the right by the inferior vena cava (Fig. 5).

The clinical literature describes the third sinus of the pericardium, located at the junction of its anterior wall with the lower one.

POSTERIOR MEDISTINUM (mediastinum posierius) - limited posteriorly by the bodies of the fifth to twelfth thoracic vertebrae, anteriorly by the pericardium, laterally by the mediastinal pleura, below by the diaphragm, above by the plane connecting the angle of the sternum with the lower edge of the fourth thoracic vertebra. The key structure of the posterior mediastinum is the descending aorta (pars desdendens aortae), which lies first on the left side of the vertebral bodies and then shifts to midline(Fig. 6). The following vessels depart from the descending aorta:

Pericardial branches (rr. pericardiaci) - supply blood back pericardium;

Bronchial arteries (aa. bronchioles) - supply blood to the wall of the bronchi and lung tissue;

Esophageal arteries (aa.oesophageales) - supply blood to the wall of the thoracic esophagus;

Mediastinal branches (rr. mediastinales) - supply blood to the lymph nodes and connective tissue of the mediastinum;

Posterior intercostal arteries (aa. inrercosiales posreriores) - pass in the intercostal spaces, supply blood to the skin and muscles of the back, spinal cord, anastomose with the anterior intercostal arteries;

Superior phrenic artery (a. phrenica superior) - branches on the upper surface of the diaphragm.

The following structures are located around the descending aorta.

The right and left main bronchi (bronchus principalis dexter et sinister) - begin from the bifurcation of the trachea at the level of the lower edge of the fourth thoracic vertebra. The left main bronchus departs at an angle of 45° relative to the median plane and is directed behind the aortic arch to the hilum of the lung. The right main bronchus arises from the trachea at an angle of 25° relative to the median plane. It is shorter than the left main bronchus and larger in diameter. This circumstance explains the significantly more frequent hits foreign bodies in the right bronchus compared to the left.

Esophagus (oesophageus) - lies first behind the left atrium and to the right of the descending aorta. In the lower third of the mediastinum, the esophagus crosses the aorta in front, moves from it to left side and is determined within the esophageal triangle, the boundaries of which are: in front of the pericardium, in the back - the descending part of the aorta, below - the diaphragm. On the anterior and posterior surfaces of the esophagus there is the esophageal plexus (plexus oesophagealis), in the formation of which two vagus nerves, as well as branches of the thoracic ganglia of the sympathetic trunk, take part.

X-ray and endoscopic examinations reveal a number of narrowings of the thoracic esophagus associated with the close interaction of its wall with neighboring organs. One of them corresponds to the aortic arch, the other to the intersection of the esophagus with the left main bronchus. Dilatation of the left atrium can also cause changes in the lumen of the esophagus when it is filled with a radiopaque substance.

Azygos vein (v. azygos) – begins in abdominal cavity, passes in the posterior mediastinum to the right of the vertebral bodies to the level of Th4, bends around the right main bronchus and flows into the superior vena cava outside the pericardial cavity. Its tributaries are all the posterior intercostal veins of the right side, as well as the bronchial, esophageal and mediastinal veins.

Hemizygos vein (v. hemiazygos) - begins in the retroperitoneal space. In the posterior mediastinum it passes behind the descending aorta, at the level of the 7th-8th thoracic vertebra it deviates towards right side and flows into the azygos vein. The tributaries of the hemizygos vein are the five lower (left) intercostal veins, the esophageal, mediastinal, and the accessory hemizygos veins.

Accessory hemizygos vein (V hemiazygos accessoria) - descends from the left side of the spinal column. The first 5-6 posterior (left) intercostal veins flow into it.

Thoracic duct (ductus thoracicus) - begins in the retroperitoneum. In the posterior mediastinum it passes between the azygos vein and the descending part of the aorta to the level of the sixth - fourth thoracic vertebrae, where it deviates to the left, crosses the esophagus from behind and continues into the upper mediastinum.

Operations on the mediastinal organs are performed for the following indications:

1. Tumors of the thymus, thyroid and parathyroid glands, as well as tumors of a neurogenic nature.

Thymic tumors are most often located in front of the aortic arch and the base of the heart. Very early, invasion of these tumors into the wall of the superior vena cava, pleura and pericardium is observed. Compression of the left brachiocephalic and superior vena cava by thymoma ranks second in frequency after obstruction of these vessels by metastases in lung cancer.

In retrosternal goiter, the glandular tissue of the thyroid gland is most often located in the space bounded below by the right main bronchus, laterally by the mediastinal pleura, anteriorly by the superior vena cava, medially by the right vagus nerve, trachea and ascending aorta.

Tumors of neurogenic nature are the most common primary tumors mediastinum. Almost all of them are associated with the posterior mediastinum and are formed from the sympathetic trunk or intercostal nerves. In some cases, these tumors appear in the neck and then descend into the upper mediastinum. Due to the fact that tumors form near the intervertebral foramina, they can enter the spinal canal, causing compression of the spinal cord.

As operational access When removing a mediastinal tumor, the following are used:

Lower cervical incision;

Median sternotomy;

Intercostal thoracotomy.

2. Mediastinitis. They are usually formed as a result of the spread of infection from the cellular spaces of the neck or during perforation of the esophagus.

Opening and drainage of ulcers of the upper mediastinum is carried out through an arcuate skin incision in the neck above the manubrium of the sternum (suprasternal mediastinotomy) by creating a canal behind the sternum. The incision can be made along the anterior edge of the sternocleidomastoid muscle, followed by opening the sheath of the neurovascular bundle or the peri-esophageal tissue space.

Drainage of the anterior mediastinum is carried out through an incision along the midline of the anterolateral abdominal wall. The opening of the abscess is carried out after dissection of the diaphragm, without violating the integrity of the peritoneum.

Opening of abscesses of the posterior mediastinum is carried out from the abdominal cavity (transabdominal mediastinotomy) or after performing a lateral thoracotomy in the 7th left intercostal space (transpleural mediastinotomy).

3. Pericarditis. They are characterized by inflammation of the visceral and parietal plates of the serous pericardium, resulting from a bacterial or viral infection, rheumatism or uremia. Pericarditis can lead to cardiac tamponade. To remove fluid and prevent tamponade, pericardial puncture (Larrey method) is used.

With the patient in a semi-sitting position, a long needle is inserted into the angle between the base of the xiphoid process and the cartilage of the UP rib. Moreover, the needle is oriented perpendicular to the surface of the anterolateral wall of the abdomen. After passing the needle to a depth of 1.5 cm, it is lowered and at an angle of 45° to the surface of the body, it is moved up parallel back surface sternum until it penetrates the anterioinferior sinus of the pericardium.

4. Heart injuries. The wound is sutured with interrupted (linear wound) or U-shaped (lacerated wound) silk sutures, bypassing the endocardium and coronary vessels. The edges of the pericardium are connected with rare sutures, the pleural cavity is drained.

5. In addition to the listed cases, operations on the mediastinal organs are performed:

To stop bleeding caused by injury or to correct vascular defects (stenosis, aneurysm);

With a tumor, injury or congenital malformations of the esophagus;

Regarding congenital and acquired heart defects, as well as acute and chronic coronary insufficiency.



The mediastinum is an anatomical space, the middle region chest. The mediastinum is limited in front by the sternum, and in the back by the spine. On each side of of this body are pleural cavities.

For various purposes ( surgical intervention, planning radiation therapy, descriptions of the localization of pathology) the mediastinum, in accordance with the scheme proposed by Twining in 1938, is divided into upper and lower, as well as anterior, posterior and middle sections.

Anterior, middle, posterior mediastinum

The anterior mediastinum is limited in front by the sternum, in the back by the brachiocephalic veins, pericardium and brachiocephalic trunk. In this space there are the internal mammary veins, the thoracic artery, the mediastinal lymph nodes and the thymus gland.

Structure of the middle mediastinum: heart, vena cava, brachiocephalic veins and brachiocephalic trunk, aortic arch, ascending aorta, phrenic veins, main bronchi, trachea, pulmonary veins and arteries.

The posterior mediastinum is limited by the trachea and pericardium in the anterior part, and in the posterior part by the spine. This part of the organ contains the esophagus, descending aorta, thoracic lymphatic duct, semi-gyzygos and azygos veins, as well as the posterior lymph nodes of the mediastinum.

Superior and inferior mediastinum

The superior mediastinum includes all anatomical structures that lie above the upper edge of the pericardium: its boundaries are the upper sternal aperture and the line drawn between the angle of the chest and intervertebral disc Th4-Th5.

The inferior mediastinum is limited by the superior edges of the diaphragm and pericardium and, in turn, is also divided into anterior, middle and posterior parts.

Classification of mediastinal tumors

Neoplasms of the organ are considered not only true tumors of the mediastinum, but also tumor-like diseases and cysts that differ in etiology, localization and course of the disease. Each of the mediastinal neoplasms originates from tissues of different origins, united only by anatomical boundaries. They are divided into:

Mediastinal tumors are detected mainly in young and middle age with equal frequency in both men and women. Although mediastinal diseases can long time do not manifest themselves and are detected only during a preventive study, there are several symptoms that characterize violations of this anatomical space:

  • Mild pain localized at the site of the tumor and radiating to the neck, shoulder, and interscapular area;
  • Pupil dilation, eyelid drooping, retraction eyeball– may occur when a tumor grows into the borderline sympathetic trunk;
  • Hoarseness of voice – originates from damage to the recurrent laryngeal nerve;
  • Heaviness, noise in the head, shortness of breath, chest pain, cyanosis and swelling of the face, swelling of the veins of the chest and neck;
  • Impaired passage of food through the esophagus.

On late stages diseases of the mediastinum, increased body temperature is observed, general weakness, arthralgic syndrome, disorder heart rate, swelling of the extremities.

Mediastinal lymphadenopathy

Lymphadenopathy or enlargement of the lymph nodes of a given organ is observed with metastases of carcinoma, lymphomas, as well as some non-tumor diseases (sarcoidosis, tuberculosis, etc.).

The main symptom of the disease is generalized or localized enlargement of the lymph nodes, however, mediastinal lymphadenopathy may have additional manifestations such as:

  • Increased body temperature, sweating;
  • Loss of body weight;
  • Frequent infection of the upper respiratory tract(tonsillitis, pharyngitis, tonsillitis);
  • Hepatomegaly and splenomegaly.

Damage to the lymph nodes, characteristic of lymphomas, can be isolated or combined with the germination of tumors into other anatomical structures (trachea, blood vessels, bronchi, pleura, esophagus, lungs).

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Mediastinum- complex anatomical and topographical region of the thoracic cavity. Its lateral borders are the right and left layers of the mediastinal pleura, the posterior wall is formed by the thoracic spine, the anterior wall is formed by the sternum, the lower edge is limited by the diaphragm. The mediastinum does not have an upper anatomical barrier, opening into the cellular space of the neck, and its conventional border is considered to be the upper edge of the sternum. The midline position of the mediastinum is maintained by intrapleural negative pressure; it changes with pneumothorax.

For convenience in determining localization pathological processes The mediastinum is conventionally divided into anterior and posterior, upper, middle and lower. The border between the anterior and posterior mediastinum is the frontal plane, which passes through the center of the stem bronchi of the lung root. According to this division, in the anterior mediastinum there remain the ascending aorta, the aortic arch with the innominate, left common carotid and left subclavian arteries extending from it, both innominate and the superior vena cava, the inferior vena cava at the confluence with the right atrium, pulmonary artery and veins, heart with pericardium, thymus, phrenic nerves, trachea and mediastinal lymph nodes. In the posterior mediastinum there are the esophagus, the azygos and semi-gypsy veins, the thoracic lymphatic duct, the vagus nerves, the descending aorta with intercostal arteries, and the borderline trunk. sympathetic nerves right and left, lymph nodes.

All anatomical formations are surrounded by loose fatty tissue, which is separated by fascial sheets, and covered along the lateral surface with pleura. Fiber is unevenly developed; it is especially well expressed in the posterior mediastinum, most weakly between the pleura and pericardium.

Organs of the anterior mediastinum

The ascending aorta begins from the left ventricle of the heart at the level of the third intercostal space. Its length is 5-6 cm. At the level of the sternocostal joint on the right, the ascending aorta turns to the left and back and passes into the aortic arch. To the right of it lies the superior vena cava, to the left is the pulmonary artery, occupying a median position.

The aortic arch is thrown from front to back through the root of the left lung. Top part the arc is projected onto the manubrium of the sternum. The left innominate vein is adjacent to it above, the transverse sinus of the heart, bifurcation below pulmonary artery, left recurrent nerve and obliterated ductus arteriosus. The pulmonary artery emerges from the conus arteriosus and lies to the left of the ascending aorta. The beginning of the pulmonary artery corresponds to the second intercostal space on the left.

The superior vena cava is formed as a result of the fusion of both innominate veins at the level of the second costosternal joint. Its length is 4-6 cm. It flows into the right atrium, where it passes partially intrapericardial.

The inferior vena cava enters the mediastinum through the opening of the same name in the diaphragm. The length of the mediastinal part is 2-3 cm. It flows into the right atrium. Pulmonary veins They emerge in two from the gates of both lungs and empty into the left atrium.

The pectoral nerves arise from the cervical plexus and descend along the anterior surface of the anterior scalene muscle and enter the chest cavity. The right thoracoabdominal nerve passes between the mediastinal pleura and the outer wall of the superior vena cava. Left - penetrates the chest cavity anterior to the aortic arch and passes through the pericardio-thoracic arteries - branches of the internal intrathoracic artery.

The heart is mostly located in the left half of the chest, occupying anterior mediastinum. On both sides it is limited by the layers of the mediastinal pleura. It distinguishes between a base, an apex and two surfaces - the diaphragmatic and sternocostal.

At the back, according to the location of the spine, adjacent to the heart is the esophagus with the vagus nerves, the thoracic aorta, on the right - the azygos vein, on the left - the semi-gypsy vein and in the azygos-aortic groove - the thoracic duct. The heart is enclosed in the cardiac membrane - one of the 3 closed serous sacs of the coelomic body cavity. The cardiac sac, fused with the tendon part of the diaphragm, forms the bed of the heart. At the top, the cardiac membrane is attached to the aorta, pulmonary artery and superior vena cava.

Embryological, anatomical, physiological and histological features of the thymus gland

The embryology of the thymus has been studied for many years. All vertebrates have a thymus gland. For the first time in 1861, Kollicker, while studying mammalian embryos, came to the conclusion that the thymus is an epithelial organ, as it is located in connection with the pharyngeal slits. It has now been established that the thymus gland develops from the epithelium of the pharyngeal intestine (branchiogenic glands). Its rudiments appear in the form of outgrowths on the lower surface of the 3rd pair of gill pouches; similar rudiments from the 4th pair are small and quickly reduced. Thus, embryogenesis data show that the thymus gland originates from 4 pouches of the pharyngeal intestine, that is, it is formed as an endocrine gland. Ductus thymopharyngeus is atrophying.

The thymus gland is well developed in newborns and especially in children under two years of age. Thus, in newborns, iron makes up an average of 4.2% of body weight, and at 50 years of age or more - 0.2%. The weight of the gland in boys is slightly greater than in girls.

In the postpubertal period, physiological involution of the thymus gland occurs, but its functioning tissue remains until old age.

The weight of the thymus gland depends on the degree of fatness of the subject (Hammar, 1926, etc.), as well as constitution.

The size and dimensions of the thymus gland are variable and depend on age. This affects the anatomical and topographic relationships of the thymus gland and other organs. In children under 5 years of age, the upper edge of the gland protrudes from behind the manubrium of the sternum. In adults, as a rule, the cervical part of the thymus gland is absent and it occupies an intrathoracic position in the anterior mediastinum. It should be noted that in children under 3 years of age cervical part The gland lies under the sternothyroid and sternohyoid muscles. Its posterior surface is adjacent to the trachea. These features should be taken into account during tracheostomy in children to avoid injury to the thymus gland and the innominate vein lying directly below it. Side surface the thymus gland on the right is in contact with jugular vein, common carotid artery, vagus nerve, on the left - adjacent to the inferior thyroid and common carotid arteries, vagus and, less commonly, the recurrent nerve.

The thoracic part of the gland is adjacent to the posterior surface of the sternum, adjacent bottom surface to the pericardium, posterior - to the superior vena cava and left innominate vein and a. anonymous. Below these formations, the iron is adjacent to the aortic arch. Its anterolateral sections are covered with pleura. In front, the gland is enveloped in a connective tissue sheet, which is a derivative of the cervical fascia. These bundles connect below with the pericardium. In the fascial bundles, muscle fibers are found that fan-shapedly penetrate into the cardiac membrane and mediastinal pleura. In adults, the thymus gland is located in the anterosuperior mediastinum and its syntopy corresponds to the thoracic part of the gland in children.

The blood supply to the thymus gland depends on age, its size and, in general, on its functional state.

The source of arterial blood supply is a. Raat-maria interna, a. thyreoidea inferior, a. anonyma and the aortic arch.

Venous outflow occurs more often into the left innominate vein, and relatively less often into the thyroid and intrathoracic veins.

It is well known that up to 4 weeks of embryonic life the thymus gland is purely epithelial formation. Subsequently, the marginal zone is populated by small lymphocytes (thymocytes). Thus, as it develops, the thymus becomes a lymphoepithelial organ. The basis of the gland is a mesh epithelial formation reticulum, which is populated by lymphocytes. By 3 months of uterine life, peculiar concentric bodies, a specific structural unit of the thymus gland, appear in the gland (V.I. Puzik, 1951).

The question of the origin of Hassall's bodies for a long time remained controversial. Multicellular Hassall bodies are formed by hypertrophy of the epithelial elements of the reticulum of the thymus. The morphological structure of the thymus gland is mainly represented by large transparent oval elongated epithelial cells, which can be different sizes, color and shape, and small dark cells of the lymphoid series. The former make up the pulpy substance of the gland, the latter mainly the cortex. The cells of the medulla reach more than high level differentiation than cortical cells (Sh. D. Galustyan, 1949). Thus, the thymus gland is built from two genetically heterogeneous components - the epithelial network and lymphocytes, that is, it represents the lymphoepithelial system. According to Sh. D. Galustyan (1949), any damage leads to a disruption of the connection between these elements that make up a single system (lymphoepithelial dissociation).

Embryogenesis data leaves no doubt that the thymus is an endocrine gland. Meanwhile, numerous studies aimed at clarifying physiological role thymus, remained unsuccessful. Reaching its greatest development in childhood, the thymus gland, as the body grows and ages, undergoes physiological involution, which affects its weight, size and morphological structure (V.I. Puzik, 1951; Hammar, 1926, etc.). Experiments on animals with the thymus gland removed have yielded conflicting results.

The study of the physiology of the thymus gland over the past decade has made it possible to come to important conclusions about its functional significance for the body. The role of the thymus gland in the body’s adaptation to exposure to harmful factors(E. 3. Yusfina, 1965; Burnet, 1964). Data were obtained on the leading role of the thymus gland in immune reactions (S. S. Mutin and Ya. A. Sigidin, 1966). It has been found that in mammals the most important source of new lymphocytes is the thymus; thymic factor leads to lymphocytosis (Burnet, 1964).

The author believes that the thymus gland apparently serves as the center for the formation of “virgin” lymphocytes, the progenitors of which do not have immunological experience, while in other centers where the majority of lymphocytes are formed, they come from predecessors that already store something in their “ immunological memory". Small lymphocytes play the role of carriers of immunological information. Thus, the physiology of the thymus gland remains largely unclear, but its importance for the body is difficult to overestimate, which is especially obvious in pathological processes.

K.T. Ovnatanyan, V.M. Kravets

Big central department The chest cavity is called the mediastinum. It separates two transversely located pleural cavities and is adjacent on each side by the mediastinal pleura. This is a whole complex, which includes numerous structures ranging from the heart and large vessels (aorta, upper and inferior vein) to the lymph nodes and nerves.

What are mediastinal tumors

Abnormal growth of new tissue always leads to the creation of neoplasms. They are found in almost any part of the body. Neoplasms originate from germ cells, and their development is possible in neurogenic (thymic) and lymphatic tissues. In medicine, they are called tumors and are often associated with cancer.

The mediastinum is located in the center of the human body and includes organs such as the heart, esophagus, trachea, aorta and thymus. This area is surrounded by the breastbone in the front, the back in the back, and the lungs on the sides. The organs of the mediastinum are divided into two floors: upper and lower; they have sections: anterior, middle and posterior.

Composition of the anterior section:

  • loose connective tissue;
  • adipose tissue;
  • The lymph nodes;
  • internal mammary vessels.

The middle part is the widest, located directly in the chest cavity. It contains:

  • pericardium;
  • heart;
  • trachea;
  • brachiocephalic vessels;
  • deep part of the cardiac plexus;
  • tracheobronchial lymph nodes.

The posterior section is located behind the pericardial sac and in front of the chest. The following organs are located in this part:

  • esophagus;
  • thoracic lymphatic duct;
  • vagus nerves;
  • posterior lymph nodes.

Since many vital organs are located in this part, affecting diseases often occur here.

Mediastinal cancer can develop in all three sections. The location of the tumor depends on the person's age.

In children, they are more likely to appear in the back. Childhood tumors are almost always benign.

In adults from 30 to 50 years old, most neoplasms appear in the anterior part; they can be both benign and malignant.

Classification of tumors

Exist Various types mediastinal tumors. The reasons that cause their formation depend on which organ of the middle part they are formed in.

New tissues are formed in the anterior part:

  • lymphomas;
  • thymomas, or tumors of the thymus gland;
  • a thyroid mass, which is most often benign, but in some cases can be malignant.

In the middle of the mediastinum, the appearance of tumors can be caused by the following processes and pathologies:

  • bronchogenic cyst (usually with benign signs);
  • pericardial cyst (a non-cancerous type of tissue on the lining of the heart);
  • vascular complications such as aortic edema;
  • benign growths in the trachea.

The following types of neoplasms occur in the posterior part of the mediastinum:

  • neurogenic formations of the mediastinum, 70% of which are non-cancerous;
  • enlarged lymph nodes, indicating that either a malignant, infectious, or systemic inflammatory process is developing in the patient’s body;
  • rare types of tumors that are created from enlargement bone marrow and are associated with severe anemia.

It is difficult to classify mediastinal cancer, because there are descriptions of over 100 types of primary and secondary neoplasms.

Symptoms of tumors

More than 40% of people with a mediastinal tumor do not have symptoms that indicate their occurrence. Most tumors are detected during a chest x-ray, which is often done for other reasons.

If symptoms do appear, it is often because the overgrown tissue is pressing on nearby organs, such as spinal cord, heart, pericardium.

The following signs can serve as signals:

  • cough;
  • shortness of breath;
  • chest pain;
  • fever, chills;
  • profuse sweating at night;
  • coughing up blood;
  • unexplained weight loss;
  • swollen lymph nodes;
  • hoarseness of voice.

Mediastinal tumors are almost always classified as primary tumors. Sometimes they develop due to metastases that spread from other diseased organs. Such formations are called secondary tumors.

Causes secondary type often unknown. Sometimes their development is associated with side diseases such as myasthenia gravis, lupus erythematosus, rheumatoid arthritis, thyroiditis.

Diagnosis of tumors

The most popular tests to assess the risk of mediastinal disease are modern views diagnosing.

  1. Computed tomography of the chest.
  2. CT-assisted core biopsy (a procedure for obtaining histological material using a thin needle under the control of computed tomography).
  3. MRI of the chest.
  4. Mediastinoscopy with biopsy.
  5. Chest X-ray.

When performing mediastinoscopy, cells are collected from the mediastinum under anesthesia. This procedure allows the doctor to accurately determine the type of tumor. A blood test is also needed to clarify the diagnosis.

Treatment of tumors

Both benign and malignant new tissues require aggressive therapy. Treatment of a mediastinal tumor depends on its location and is determined by the doctor. Benign ones can put pressure on adjacent organs and disrupt their functions. Cancerous tumors can move to other areas and metastasize, which subsequently leads to various complications.

The best treatment is surgery to remove the mass.

Thymomas and thymic carcinomas require mandatory surgical intervention. Postoperative treatment includes chemotherapy. Types of surgery used in treatment:

  • thoracoscopy (minimally invasive method);
  • mediastinoscopy (invasive method);
  • thoracotomy (the procedure is performed through an incision in the chest).

Neurogenic formations found in the posterior mediastinum are treated surgically.

Compared to traditional surgery, patients who undergo minimally invasive surgery have several advantages. Postoperative pain in such cases is insignificant, the length of stay in the hospital is reduced. After such operations there is fast recovery and returning to work. Other possible benefits include a reduced risk of infection and reduced bleeding.

The mediastinum is the part of the chest cavity bounded below by the diaphragm, in front by the sternum, and behind by the sternum. thoracic region the spine and the necks of the ribs, on the sides - the pleural layers (right and left mediastinal pleura). Above the manubrium of the sternum, the mediastinum passes into the cellular spaces of the neck. The conventional upper border of the mediastinum is the horizontal plane passing along top edge manubrium of the sternum. A conventional line drawn from the place of attachment of the manubrium of the sternum to its body towards the IV thoracic vertebra divides the mediastinum into upper and lower. Frontal plane drawn along back wall trachea, divides the superior mediastinum into anterior and posterior sections. The cardiac bursa divides the inferior mediastinum into anterior, middle and lower sections(Fig. 16.1).

In the anterior section of the upper mediastinum there are the proximal sections of the trachea, the thymus gland, the aortic arch and its branches, the upper section of the superior vena cava and its main tributaries. In the posterior section there is the upper part of the esophagus, sympathetic trunks, vagus nerves, and the thoracic lymphatic duct. In the anterior mediastinum between the pericardium and the sternum there are the distal part of the thymus gland, fatty tissue

ka, lymph nodes. The middle mediastinum contains the pericardium, heart, intrapericardial sections large vessels, bifurcation of the trachea and main bronchi, bifurcation lymph nodes. In the posterior mediastinum, limited in front by the bifurcation of the trachea and pericardium, and behind by the lower thoracic spine, there are the esophagus, the descending thoracic aorta, the thoracic lymphatic duct, sympathetic and parasympathetic (vagus) nerves, and lymph nodes.

Research methods

To diagnose diseases of the mediastinum (tumors, cysts, acute and chronic mediastinitis), the same instrumental methods are used that are used to diagnose lesions of organs located in this space. They are described in the corresponding chapters.

16.1. Mediastinal injuries

There are open and closed injuries to the mediastinum and organs located in it.

Clinical picture and diagnosis. Clinical manifestations depend on the nature of the injury and which organ of the mediastinum is damaged, on the intensity of internal or external bleeding. With a closed injury, hemorrhages almost always occur with the formation of a hematoma, which can lead to compression of the vital important organs(primarily thin-walled veins of the mediastinum). When the esophagus, trachea and main bronchi are ruptured, mediastinal emphysema and mediastinitis develop. Clinically, emphysema is manifested by intense pain behind the sternum, characteristic crepitus in the subcutaneous tissue of the anterior surface of the neck, face, and less commonly the chest wall.

The diagnosis is based on anamnesis (clarification of the mechanism of injury), the sequence of development of symptoms and objective examination data, identifying symptoms characteristic of the damaged organ. At x-ray examination a shift of the mediastinum to one side or another, an expansion of its shadow due to hemorrhage, is visible. Significant clearing of the mediastinal shadow is a radiological symptom of mediastinal emphysema.

Open injuries

usually combined with damage to the mediastinal organs (which is accompanied by corresponding symptoms), as well as bleeding, development of pneumonia

Rice. 16.1. Anatomy of the mediastinum (schematic MOMediastinum.

image). Treatment sent before

1 - upper anterior mediastinum; 2 - posterior medial TOTAL ON NORMZ LYZATION OF FUNCTIONS

nie; 3 - anterior mediastinum; 4 - middle mediastinum. VITAL ORGANS (SVRD-

ca and lungs). Antishock therapy is carried out, and if the frame function of the chest is impaired, artificial ventilation and various methods of fixation are used. Indications for surgical treatment are compression of vital organs with a sharp disruption of their functions, ruptures of the esophagus, trachea, main bronchi, large blood vessels with ongoing bleeding.

For open injuries, surgical treatment is indicated. The choice of surgical method depends on the nature of the damage to a particular organ, the degree of infection of the wound and the general condition of the patient.

16.2. Inflammatory diseases

16.2.1. Descending necrotizing acute mediastinitis

Acute purulent inflammation of the mediastinal tissue occurs in most cases in the form of necrotizing, rapidly progressing phlegmon.

Etiology and pathogenesis. This form of acute mediastinitis, arising from acute purulent foci located on the neck and head, is the most common. Average age Those affected are 32-36 years old, men get sick 6 times more often than women. The cause in more than 50% of cases is odontogenic mixed aerobic-anaerobic infection, less often the infection comes from retropharyngeal abscesses, iatrogenic injuries to the pharynx, lymphadenitis of the cervical lymph nodes and acute thyroiditis. The infection quickly descends through the fascial spaces of the neck (mainly along the visceral - retroesophageal) into the mediastinum and causes severe necrotizing inflammation of the tissues of the latter. The rapid spread of infection to the mediastinum occurs due to gravity and the pressure gradient resulting from the suction effect of respiratory movements.

Descending necrotizing mediastinitis differs from other forms of acute mediastinitis in the unusually rapid development of the inflammatory process and severe sepsis, which can be fatal within 24-48 hours. Despite aggressive surgical intervention and modern antibiotic therapy, mortality reaches 30%.

Perforation of the esophagus (damage by a foreign body or instrument during diagnostic and therapeutic procedures), failure of sutures after operations on the esophagus can also become sources of descending infection of the mediastinum. Mediastinitis that occurs under these circumstances should be distinguished from necrotizing descending mediastinitis, since it constitutes a separate clinical entity and requires a special treatment algorithm.

Clinical picture and diagnosis. Characteristic signs of descending necrotizing mediastinitis are high body temperature, chills, pain localized in the neck and oropharynx, and respiratory failure. Sometimes there is redness and swelling in the chin area or neck. The appearance of signs of inflammation outside oral cavity serves as a signal to begin immediate surgical treatment. Crepitus in this area may be due to anaerobic infection or emphysema due to injury to the trachea or esophagus. Difficulty breathing is a sign of threatened laryngeal edema and airway obstruction.

X-ray examination reveals an increase in retro-

visceral (retroesophageal) space, the presence of fluid or edema in this area, anterior displacement of the trachea, mediastinal emphysema, smoothing of lordosis in cervical spine spine. A CT scan should be performed immediately to confirm the diagnosis. Detection of tissue edema, accumulation of fluid in the mediastinum and in the pleural cavity, emphysema of the mediastinum and neck makes it possible to establish a diagnosis and clarify the boundaries of the spread of infection.

Treatment. Rapid spread of infection and the possibility of developing sepsis with fatal within 24-48 hours, it is obligatory to start treatment as early as possible, even if there is doubt about the presumptive diagnosis. It is necessary to maintain normal breathing, apply massive antibiotic therapy, and early surgical intervention is indicated. With swelling of the larynx and vocal cords Airway patency is ensured by tracheal intubation or tracheotomy. For antibiotic therapy, broad-spectrum drugs that can effectively suppress the development of anaerobic and aerobic infections are selected empirically. After determining the sensitivity of the infection to antibiotics, appropriate drugs are prescribed. Treatment is recommended to begin with penicillin G (benzylpenicillin) - 12-20 million units intravenously or intramuscularly in combination with clindamycin (600-900 mg intravenously at a rate of no more than 30 mg per minute) or metronidazole. A good effect is observed with a combination of cephalosporins and carbopenems.

The most important component of treatment is surgery. The incision is made along the anterior edge of m. sternocleidomastoideus. It allows you to open all three fascial spaces of the neck. During the operation, non-viable tissues are excised and the cavities are drained. From this incision the surgeon cannot gain access to the infected tissues of the mediastinum, therefore it is recommended in all cases to additionally perform a thoracotomy (transverse sternotomy) to open and drain the abscesses. IN last years To drain the mediastinum, interventions using video technology are used. Along with surgical intervention, the entire arsenal of intensive care means is used. Mortality with intensive treatment is 20-30%

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