Uberon definition : The upper esophageal sphincter (UES) (also called the Pharyngoesophageal sphincter)
refers to the superior portion of the esophagus. Unlike the lower esophageal sphincter,
it consists of striated muscle and is under conscious control. The primary muscle
of the UES is the cricopharyngeus portion of the inferior pharyngeal constrictor.
During swallowing the upper esophageal sphincter opens so the bolus can pass into
the esophagus. A secondary role of the UES is to reduce backflow from the esophagus
into the pharynx.;
The upper esophageal sphincter (UES) (also called the Pharyngoesophageal sphincter)
refers to the superior portion of the esophagus. Unlike the lower esophageal sphincter,
it consists of striated muscle and is under conscious control. The primary muscle
of the UES is the cricopharyngeus portion of the inferior pharyngeal constrictor.
During swallowing the upper esophageal sphincter opens so the bolus can pass into
the esophagus. A secondary role of the UES is to reduce backflow from the esophagus
into the pharynx.