An expandable, saclike organ, located below the diaphragm in the upper left part of the abdomen, which forms part of the digestive tract between the esophagus and the duodenum. The stomach receives partly digest food from the esophagus through the cardia sphincter. The food is churned by muscular layers of the stomach and mixed with the secretions of the gastric glands.The liquid mass then passes through the pyloric sphincter to the duodenum.