part of part of deep to superficial to contributes to morphology of myenteric nerve plexus stomach muscularis externa stomach smooth muscle circular layer middle circular muscle layer of stomach stratum circulare gastris circular muscle layer of stomach stratum circulare tunicae muscularis gastricae UBERON:0008857 SCTID:2746007 stratum circulare (tunica muscularis)(gaster) MA:0001628 FMA:14911 The middle layer of the muscularis; it is continuous with the circular layer of the esophagus, but is absent in the fundus and lies concentric to the longitudinal axis of the stomach; the circular layer is normally tonically constricted forming a functional pyloric sphincter, which controls the movement of chyme into the duodenum. circular layer of gastric muscularis FMA and MP disagree as to whether the circular layer is middle or innermost This layer wraps in a circular orientation around the pylorus, and is held in a constricted state normally. The normal constriction of this muscle is what creates the pyloric sphincter, which controls the movement of chyme into the duodenum. This layer is concentric to the longitudinal axis of the stomach. (note: chyme is a thick and acidic mixture of acidic digestive fluids and partially digested food, which moves from the stomach to the small intestine as digestion moves along the digestive tract.) stomach smooth muscle inner oblique layer circular muscle layer of muscular coat