Esophagus in endoscopic image

The esophagus is a tube that runs from the pharynx to the stomach. The length of the esophagus depends on gender, age, head position (shortened when flexed, lengthened when extended), and is on average 23-24 cm for women and 25-26 cm for men. It begins at the level of the sixth cervical vertebra and ends at the level of the eleventh thoracic vertebra.

The esophagus consists of 4 sections:

1. Cervical.
2. Chest.
3. Diaphragmatic.
4. Abdominal.

Cervical section. It goes from the 6th cervical to the 2nd thoracic vertebra. The entrance to the esophagus depends on the position of the head: when flexed - at the level of the 7th cervical vertebra, when extended - at the level of the 5th-6th. This is important when detecting foreign bodies. The inner upper border of the esophagus is the labial fold, which is formed by a hypertrophied muscle (cricopharyngeal). When inhaling, this muscle contracts and closes the entrance to the esophagus, preventing aerophagia. The length of the cervical esophagus is 5-6 cm. In older people, it shortens due to the lowering of the larynx. In this section of the esophagus, 2/3 to 3/4 of all foreign bodies are retained. From the outside, the esophagus in this section is covered with loose tissue, which provides it with high mobility. This tissue passes into the superior mediastinum - if the esophagus is damaged, air enters the superior mediastinum. At the back, the esophagus in this section is adjacent to the spine, in front - to the trachea, and on the sides are the recurrent nerves and the thyroid gland.

Thoracic section. It goes from the 2nd thoracic vertebra to the esophageal opening of the diaphragm (the IX thoracic vertebra). This is the longest section: 16-18 cm. It is covered with a thin layer of tissue on the outside and is fixed to the spinal fascia. At the level of the V thoracic vertebra, the left main bronchus or the bifurcation area of the trachea is adjacent to the esophagus. Congenital and acquired tracheoesophageal fistulas are common in this area. Large paraesophageal and bifurcation lymph nodes are located on the sides of the esophagus. When they are enlarged, indentations in the esophagus are visible.

Diaphragmatic section. The most important in functional terms. Its length is 1.5-2.0 cm. It is located at the level of the esophageal opening of the diaphragm. At this level, the proper adventitia of the esophagus is closely connected with the diaphragmatic ligaments. Here, the esophageal-diaphragmatic membranes are formed, which play a role in the formation of hernias of the esophageal opening

Abdominal section. The most variable: from 1 to 6 cm. It goes from the esophageal opening of the diaphragm to the 11th thoracic vertebra. With age, this section lengthens. It is covered on the outside with loose tissue, which provides greater mobility in the longitudinal direction. The internal and lower border of the esophagus is the cardiac fold.

In addition to the three anatomical constrictions, there are 4 physiological constrictions in the esophagus:

1. The mouth of the esophagus (VI cervical vertebra).
2. In the area of intersection with the aortic arch (III-IV thoracic vertebra) - less pronounced. Frequent localization of post-burn scars here, as well as foreign bodies, is explained not only by the presence of aortic stenosis of the esophagus, but also by the lateral bend of the esophagus above it.
3. In the area of the bifurcation of the trachea (V-VI thoracic vertebra) and the intersection with the left main bronchus, where the latter is somewhat pressed into the esophagus.
4. In the area of the esophageal opening of the diaphragm (IX-X thoracic vertebrae).

Distance from the upper incisors to the constrictions:

1. 16-20 cm.
2. 23 cm.
3. 26 cm.
4. 36-37 cm.

The distance from the incisors of the upper jaw to the cardia is 40 cm. The diameter of the esophagus in the cervical region is 1.8-2.0 cm, in the thoracic and abdominal regions 2.1-2.5 cm. The diameter of the esophagus increases during inhalation, and decreases during exhalation.

The wall of the esophagus consists of 4 layers:

• Mucous membrane:
  • epithelium,
  • lamina propria of the mucous membrane,
  • muscularis mucosa.
• Submucosal layer.
• Muscular layer.
  • circular muscular layer,
  • longitudinal muscle layer.
• Adventitia.

The epithelium is multilayered, flat, non-keratinizing. The mucous membrane is normally light pink with a delicate vascular pattern. In the area of the cardia, the multilayered flat epithelium of the esophagus passes into the columnar epithelium of the stomach, forming a serrated line. This is important in the diagnosis of esophagitis and esophageal cancer, in which the clarity of the line is lost; in cancer, the edges may be corroded. There may be up to 24 layers of epithelium. The upper and lower cardiac glands are located in the mucous membrane of the cervical and abdominal sections of the esophagus. There are 5 times more of them in the abdominal section of the esophagus than in the stomach. They contain endocrine glands that secrete intestinal hormones: gastrin, secretin, somatostatin, vasopressin. Gastrin and secretin are involved in the motility and trophism of the digestive tract. The glands are located in the proper plate of the mucous membrane. The muscularis mucosa consists of smooth muscle fibers.

The submucosal layer is formed by loose connective tissue, the severity of which determines the size of the folds.

The muscular membrane consists of 2 types of fibers:

1. Striated - located mainly in the upper 1/3 of the esophagus, in the middle 1/3 they turn into smooth.
2. Smooth muscle fibers - the lower 1/3 of the esophagus consists exclusively of them.

The muscular coat consists of two layers - the inner circular and the outer longitudinal. The circular layer, located along its entire length, is thinner in the initial part of the esophagus; gradually thickening, it reaches its maximum dimensions at the diaphragm. The layer of longitudinal muscle fibers becomes thinner in the section of the esophagus located behind the trachea, and in the final sections of the esophagus it thickens. In general, the muscular coat of the esophagus in the initial section, especially in the pharynx, is relatively thin; it gradually thickens in the direction of the abdominal part. Both layers of muscles are separated by connective tissue, in which nerve plexuses are located.

Adventitia is a loose connective tissue that surrounds the esophagus from the outside. It is well expressed above the diaphragm and at the junction of the esophagus and the stomach.

The blood supply to the esophagus is less developed than in the stomach, since there is no single esophageal artery. Different parts of the esophagus are supplied with blood differently.

• Cervical region: inferior thyroid, pharyngeal and subclavian arteries.
• Thoracic region: branches of the subclavian, inferior thyroid, bronchial, intercostal arteries, thoracic aorta.
• Abdominal region: from the left inferior diaphragmatic and left gastric arteries.

Venous outflowis carried out through the veins corresponding to the arteries that feed the esophagus.

• Cervical region: into the veins of the thyroid gland and into the innominate and superior vena cava.
• Thoracic section: via the esophageal and intercostal branches into the azygos and hemiazygos veins and, consequently, into the superior vena cava. From the lower third of the thoracic part of the esophagus, venous blood is directed into the portal system via the branches of the left gastric vein and the upper branches of the splenic vein. Part of the venous blood from this part of the esophagus is diverted by the left inferior phrenic vein into the inferior vena cava system.
• Abdominal section: into the tributaries of the portal vein. In the abdominal section and in the area of the cardioesophageal junction there is a portocaval anastomosis, which is the first to expand in liver cirrhosis.

Lymphatic systemformed by two groups of lymphatic vessels - the main network in the submucosal layer and the network in the muscular layer, which partially connects with the submucosal network. In the submucosal layer, the lymphatic vessels go both in the direction of the nearest regional lymph nodes and longitudinally along the esophagus. In this case, the lymph outflow in the longitudinal lymphatic vessels in the upper 2/3 of the esophagus occurs upward, and in the lower third of the esophagus - downward. This explains the metastasis not only to the nearest, but also to distant lymph nodes. From the muscular network, the lymph outflow goes to the nearest regional lymph nodes.

Innervation of the esophagus.

Parasympathetic:

• vagus nerve,
• recurrent nerve.

Sympathetic: nodes of the borderline, aortic, cardiac plexuses, ganglia in the subcardia.

The esophagus has its own innervation - the intramural nervous system, which is represented by Doppler cells and consists of three closely related plexuses:

• adventitial,
• intermuscular,
• submucosal.

They determine the internal autonomy of innervation and local innervation of the motor function of the esophagus. The esophagus is also regulated by the central nervous system.

Cardia. This is the place where the esophagus passes into the stomach, acting as a functional sphincter and preventing reflux of gastric contents into the esophagus. The cardiac sphincter is formed by thickening of the circular muscular layer of the esophagus. In the area of the cardia, its thickness is 2-2.5 times greater than in the esophagus. In the area of the cardiac notch, the circular layers cross and pass into the stomach.

The closing function of the cardia depends on the physiological adequacy of the muscle fibers of the lower esophageal sphincter, the function of the right diaphragmatic leg and the muscles of the stomach, the acute angle between the left wall of the esophagus and the bottom of the stomach (angle of His), the diaphragmatic-esophageal membrane of Laimer, as well as the folds of the gastric mucosa (Gubarev's folds), which, under the action of the gastric gas bubble, tightly adhere to the right edge of the esophageal opening of the diaphragm.

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