overlaps overlaps composed primarily of striated muscle tissue upper esophageal sphincter http://upload.wikimedia.org/wikipedia/commons/2/22/Musculusconstrictorpharyngisinferior.png pharyngoesophageal sphincter upper oesophageal sphincter upper esophageal sphincter muscle UMLS:C1451819 UBERON:0007268 Wikipedia:Upper_esophageal_sphincter FMA:265203 NCIT:C33836 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. MESH:D049631 striated muscle sphincter upper esophagus