angular sphincter thickening of the circular muscular layer forming a proposed intermediate sphincter at the level of the angular notch of the stomach. Although the thickening of the circular muscle may indicate the commencement of the pyloric antrum, true functional sphincteric activity distinct from the other peristaltic contractions of the stomach is not observed although some of these may in fact temporarily close off the antrum from the remainder of the stomach lumen. SYN: antral sphincter, midgastric transverse sphincter, sphincter antri, sphincter intermedius, sphincter of antrum, sphincter of gastric antrum.