The stomach is a J-shaped muscular organ in the upper part of the abdomen. It stores and digests food by producing acids (substances that create chemical reactions) and digestive juices. This mix of enzymes and digestive juices breaks down food so it can pass on into our small intestines. The stomach is divided into three regions, the fundus, body, and the antrum. When the stomach is inactive, the pyloric sphincter is relaxed and opened . When the stomach contains food, the sphincters are closed. It has two  curvatures, the lesser curvature is short and lies on the upper  surface of the stomach. The greater curvature is long and extends from fundus to the pyloric sphincter.