Structurally the wall of the stomach is made up of four layers of tissue. These are
1. An outer covering of the serous membrane (the peritoneum)
2. A muscle layer which intern is made up of three layers of visceral muscle fibres namely longitudinal, circular and oblique.
3. A sub mucous layer consisting of loose areolar tissue carrying blood vessels, lymphatics and nerves.
4. The mucous membrane constituting the inner most layers is thick and smooth having a velvety surface when the stomach is full. When the stomach is empty the mucous membrane is thrown into a number of irregular folds or rugae. These folds open up at the entry of the food and allow the stomach to expand to accommodate a large quantity of food.