Читать книгу The Esophagus - Группа авторов - Страница 141

There is a closed 3–4 cm long high‐pressure zone at the distal end of the esophagus that functions as an antireflux barrier and separates negative intrathoracic pressure in the esophagus from positive intra‐abdominal pressure in the stomach. This high‐pressure zone is considered to normally have two components: an intrinsic smooth muscle sphincter known as the LES, and the surrounding diaphragmatic crura that functions as an external sphincter [281]. When normally positioned, the LES is therefore part of a more complex structural arrangement called the esophagogastric junction (EGJ) that includes the phrenoesophageal membrane and the hiatal portion of the diaphragm. 3D high‐resolution manometry studies have demonstrated that the LES is asymmetric, and both the intrinsic LES and the crural diaphragm contribute to the basal tone of the EGJ [282].