A constrictor muscle is a type of muscle that functions to narrow or constrict a passage or opening in the body. These muscles are typically found in various organs, such as the esophagus, where they help move food down to the stomach through rhythmic contractions. They play a crucial role in processes like swallowing and digestion. In addition to the esophagus, constrictor muscles are also present in the pharynx and anus. In the pharynx, they assist in the swallowing process by pushing food into the esophagus. In the anus, they help control the release of waste from the body, maintaining continence.