Читать книгу The Esophagus - Группа авторов - Страница 123

The UES has a resting pressure that keeps the lumen closed to separate the atmospheric pressure above from the negative intrathoracic pressure below and to prevent esophagopharyngeal reflux. Cessation of tonic vagal excitation of the UES initiates relaxation; the UES is pulled open by the hyoid bone moving upward and forward during swallowing, and sphincter opening ends when pharyngeal contraction arrives at the UES [59]. The sphincter relaxes either with a voluntary swallow or involuntarily during belching and vomiting to permit orad movement of content. In addition, a “pharyngeal swallow” that involves the pharynx, UES, and esophageal body can be initiated by pharyngeal stimulation [13].