Human Anatomy, Part 1 - K. A. Dyubenko, A. K. Kolomiysev, Yu. B. Chaykovsky 2002

Special Section
Splanchnology, splanchnologia [the study of viscera] — Digestive system, systema digestorium
Structure of the esophagus

The Esophagus consists of three tunics (Fig. 223):

- mucous membrane, tunica mucosa;

- muscular coat, tunica muscularis;

- Connective Tissue coat (adventitia), tunica adventitia.

The mucous membrane, tunica mucosa, has a folded relief that smooths out during the passage of food. In cross-section, it has a stellate contour.

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Fig. 223. Cross-section of the esophagus

The mucous membrane consists of a non-keratinized stratified squamous epithelium and a muscular lamina. It contains mucous and cardiac glands, as well as isolated lymphoid nodules. The mucous membrane has a pink color, is moist, and is examined using an esophagoscope and X-ray imaging for diagnostic purposes.

The muscular coat, tunica muscularis, consists of an outer longitudinal and an inner circular layer. The cervical part of the esophagus consists of striated Muscle; the thoracic part, of striated and smooth muscle; and the lower third, of smooth muscle. The muscle fibers of the circular layer in the region where the Pharynx transitions into the esophagus (15-20 cm from the incisors) form a physiological sphincter—the upper esophageal (or cricopharyngeal) sphincter. It prevents the aspiration of air into the esophagus. The lower esophageal sphincter is located in the region where the esophagus transitions into The Stomach. It is formed by smooth muscle fibers which, upon contraction, prevent the reflux (backflow) of gastric contents into the esophagus.

The connective tissue coat (adventitia), tunica adventitia, bounds the esophagus externally, anchors it to adjacent Organs, and allows the esophagus to change its lumen.

X-ray Anatomy of the Esophagus. The esophagus is examined in the upright position, with X-rays directed in the posteroanterior direction. The Water/144.html">Origin of the esophagus is projected at the level of C VI, which corresponds to the site of the first physiological constriction of the esophagus. Here and further down, the esophagus occupies a median position, and at the level of Th III–IV, it curves slightly to the left and right, below the aortic arch at Th VI–VII. At the level of Th IV–VI, the second constriction of the esophagus is recorded. At the level of Th X, the esophagus passes through the Diaphragm (the third constriction of the esophagus) and terminates at the level of Th XI, where its distal segment sharply turns to the left and empties into the cardiac part of the stomach. When a person is rotated around the longitudinal axis, the esophagus moves out of the shadow of The Heart, great vessels, and Sternum. Most of it is located in the clear space between the shadows of THE Vertebral Column, heart, and great vessels. In this position, not only the physiological constrictions and dilatations are clearly visible, but also various anatomical variations of its position. During esophagoscopy, the pharyngeal segment (laryngopharynx) and the proper segments of the esophagus are studied: the tracheal segment (12 cm), aortic segment (2.5 cm), aortobronchial segment (between the lower margin of the aortic arch and the upper-outer margin of the left bronchus); the bronchial segment is located at the level of the tracheal bifurcation. The subbronchial segment of the esophagus is about 5 cm long and is situated at the level of the tracheal bifurcation and the upper margin of the atrium. The sternopericardial segment of the esophagus touches the heart anteriorly, while the subdiaphragmatic segment, about 3-4 cm long, is tilted forward and to the left. The intra-diaphragmatic segment of the esophagus passes through the fibrous ring of the diaphragm, and the abdominal segment has an average length of 3 cm. On radiographs in the anterior projection, the esophagus appears as a segment with clear contours; its position, dimensions, and the state of the mucosal folds in specific areas are determined.

Blood supply to the esophagus comes from various sources: the cervical part receives blood from the inferior thyroid artery; the thoracic part, from the esophageal Branches of the Thoracic Aorta; and the abdominal part, from the inferior phrenic and left gastric Arteries. Venous drainage is directed from the cervical part of the esophagus into the brachiocephalic vein; from the thoracic part, into the azygos and hemiazygos Veins; and from the abdominal part, into tributaries of the portal vein.

Lymphatic vessels drain Lymph from the cervical part of the esophagus into the deep cervical Lymph Nodes; from the thoracic part, into the tracheal, tracheobronchial, and posterior mediastinal nodes; and from the abdominal part, into the left gastric and pancreaticosplenic nodes.

Innervation of the esophagus is provided by the vagus nerves and branches of the Sympathetic trunk ganglia, which form the esophageal plexus. From the adventitial esophageal plexus, nerve bundles penetrate into the deep layers of the esophagus, where they form the myenteric and submucosal plexuses.