Pylorus

The pylorus is located at the distal end of the stomach. It is a distal constriction marking the transition between the stomach and the duodenum and containing the sphincter. It opens in the duodenum by the pyloric orifice (ostium pyloricum)

It functions as a sphincter, regulating the passage of partially digested food (chyme) from the stomach into the small intestine. The pylorus controls gastric emptying by adjusting the outflow resistance to match physiological needs, allowing the passage of isotonic fluids while retaining larger particles for further digestion.

The torus pyloricus (in pigs and ruminants) is a protuberance in the pylorus formed by the circular muscle at the end of the lesser curvature, fat, and the mucous membrane.