Upper esophageal sphincter
Encyclopedia
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 yet, is not under conscious control. Opening of the UES is triggered by the swallow reflex. 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. It also makes the sound of eructation.
Esophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...
.
Unlike the lower esophageal sphincter, it consists of striated muscle
Striated muscle
Striated muscle tissue is a form of fibers that are combined into parallel fibers. More specifically, it can refer to:* Cardiac muscle .* Skeletal muscle* Branchiomeric muscles...
and yet, is not under conscious control. Opening of the UES is triggered by the swallow reflex. 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. It also makes the sound of eructation.