The stomach is a part of the digestion system and essential for the nutrient supply to the body. Its acidic gastric juice acts as a barrier to bacteria which could otherwise infiltrate the intestines and other abdominal organs.

The stomach is anatomically divided into four main parts:

• Cardia is situated below the diaphragm, the abdominal part of the esophagus continues as the cardiac part of the stomach. Here the ingested food reaches the stomach through the cardiac orifice - a narrow ring around the esophageal opening. It has a physiological “cardiac sphincter” – a thick muscular wall that can be tightly closed to prevent stomach reflux.

• Fundus is a dome-like part filled with gas (in the upright body position), sharply separated from the cardia by the cardiac incisure. Can be dilated by gas, fluid, food, or any combination; can be seen in a radiograph as containing a “stomach bubble”.

• Body is the largest part of the stomach, between the fundus and pyloric antrum; forms the lesser curvature (cranial) and the greater curvature (caudal).

• Pylorus (pyloric part) lies perpendicular to the long axis of the stomach at the level of the transpyloric plane (level of the L1 vertebra). In an erect patient pyloric location varies from the L2 through L4 vertebra. It has a pyloric sphincter thickened internally by an enlarged circular muscle layer. It regulates the passage of food from the stomach to the duodenum.

These subdivisions are also used when discussing X-rays of the barium-filled stomach.

NOTE: these divisions do not correspond to the histological classification, which divides the stomach into two areas – fundus and antrum – based on mucosal gland structure. 

The stomach also has two curvatures:

• Lesser curvature - a short concave right border of the stomach (lesser omentum attaches there);

• Greater curvature - long convex left and inferior border of the stomach (greater omentum is suspended from this curvature).