Upper esophageal sphincter (UES) has also been referred to as the inferior pharyngeal sphincter because it is located at the lower end of pharynx and guards the entrance into the esophagus. It has two major functions: (1) to prevent air from entering into the esophagus during breathing and (2) to prevent reflux of esophageal contents into the pharynx to guard airway aspiration. The upper esophageal sphincter (UES) is a bundle of muscles at the top of the esophagus. The muscles of the UES are under conscious control, used when breathing, eating, belching, and vomiting. They keep food and secretions from going down the windpipe.
Related journals of Upper esophagus
Oral Oncology, Journal of Oral Hygiene & Health, Oral cancer, JAMA Otolaryngology - Head and Neck Surgery