Diaphragmatic constriction

The diaphragmatic constriction is the lowest of the normal physiological constrictions of the esophagus and occurs where the esophagus passes through the esophageal hiatus of the diaphragm at the level of the T10 vertebra. This constriction is produced by the muscular fibers of the right crus of the diaphragm, which encircle the esophageal hiatus and exert a sphincter-like effect on the esophagus.

As the thoracic esophagus descends through the posterior mediastinum, it passes anterior to the aorta and enters the abdomen through the esophageal hiatus. Immediately above the hiatus, the esophagus exhibits a slight fusiform dilatation known as the phrenic ampulla. Upon traversing the diaphragm, the esophagus continues as the short abdominal part of the esophagus before joining the stomach at the cardiac orifice, typically at the level of T11.

Antireflux mechanism of gastroesophageal junction and hiatal hernia

The diaphragmatic constriction is situated approximately 40 cm from the upper incisor teeth during endoscopic examination. It represents an important component of the antireflux mechanism of the gastroesophageal junction. The right crus of the diaphragm acts as an extrinsic physiological sphincter, compressing the esophagus during inspiration and helping to prevent the reflux of gastric contents into the esophagus. This mechanism functions in conjunction with the lower esophageal sphincter (LES).

Weakening of the diaphragmatic support or widening of the esophageal hiatus may result in a hiatal hernia, in which part of the stomach herniates through the diaphragm into the thoracic cavity. This condition is commonly associated with gastroesophageal reflux disease (GERD).