part of part of contributes to morphology of composed primarily of smooth muscle tissue wall of stomach stomach smooth muscle muscular coat stomach muscularis externa SCTID:362132003 tunica muscularis gastris UBERON:0008856 FMA:14909 tunica muscularis (gaster) muscle layer of stomach gastric muscularis The smooth muscle layer of the stomach wall that functions to churn and mix food and gastric secretions as well as to move food along the digestive tract to the intestines. muscularis externa of stomach the muscularis externa in the stomach differs from that of other GI organs in that it has three layers of smooth muscle instead of two muscular coat of digestive tract layer of smooth muscle tissue