The Stomach is a pyriform sac with two openings- the oesophageal or cardiac, opening, and the pylorus, opening into the duodenum. The stomach has two ends, two surfaces, two curvatures, and two openings.

The large cardiac end is directed backwards and to the left and the narrow pyloric end is directed to the right. The stomach lies in the left hypochondrium and left half of the epigastrium, under the left cupola of the diaphragm. In extreme extension it may reach down below the subcostal plane.

Fig. 47. - The Stomach.

The length of the stomach is 10 to 11 inches and its greatest diameter 4 to 4 1/2 inches; its capacity as a rule does not exceed 40 ounces (1 quart).

The stomach is composed of three layers of muscles with their fibres running in different directions, which insures thorough contractions of all parts taking place during digestion. When empty, the stomach in the healthy state is not collapsed, but contracted.

The stomach lies in a cavity surrounded by other organs, and to this cavity is often given the name of the stomach chamber.

The Stomach Chamber

The roof is formed of the under surface of the left lobe of the liver and the left cupola of the diaphragm; this latter slopes down behind and forms the posterior wall. The anterior wall is formed by the abdominal wall between the ribs on the left and the liver on the right. The floor on which the stomach rests is formed by the top of the left kidney and suprarenal capsule, the gastric surface of the spleen, upper surface of the pancreas, and coils of small intestine.