Stomach parts and curvatures
The stomach is a part of the digestive tract; therefore, it is essential for the nutrient supply to the body. Its acidic gastric juice is a barrier to bacteria that could otherwise infiltrate the intestines and other abdominal organs.
The stomach is anatomically composed of four parts:
- Cardia - situated below the diaphragm; it surrounds the cardiac opening (orifice) and is the very first portion that receives ingested food; it is a continuation of the abdominal part of the esophagus; it has a physiological cardiac sphincter (lower esophageal sphincter) that is located between the stomach and the esophagus at the gastroesophageal junction (corresponds to the eleventh thoracic vertebra (T11)), this sphincter is a physiological sphincter;
- Fundus - a dome-shaped superior dilation of the stomach located above and left to the cardiac opening; in the upright body position, it is filled with gas; it can become dilated by gas, fluid, food, or any other combination; can be seen in a radiograph as containing a “stomach bubble”;
- Body - also called the corpus; the largest part of the stomach positioned between the fundus and pyloric antrum;
- Pyloric part - also known as simply the pylorus; the most distal part that connects the stomach with the duodenum and can be subdivided into two smaller areas - the pyloric antrum and the pyloric canal; the pyloric antrum is wider, while the pyloric canal is narrower and it is connected to the duodenum via the pyloric orifice; this opening is controlled by the pyloric sphincter - a circular layer of smooth muscles.
These subdivisions are also used when discussing X-rays of the barium-filled stomach.
Note: These anatomical parts of the stomach do not correspond to the histological classification. Histologically, the stomach is divided only into three portions instead of four. The body and fundus have the same microscopic characteristics.
Curvatures and surfaces
The stomach has a characteristic J-shape that is created by two curved borders known as its curvatures:
- Greater curvature - long and convex curvature found on the left side; it goes from the cardiac notch (formed between the abdominal esophagus and the fundus of the stomach) to the pyloric part;
- Lesser curvature - short and concave curvature on the right side of the stomach; its distal ending contains a small incisure called the angular notch that marks the intersection site between the body and the pyloric part of the stomach.
The stomach has two surfaces found between both curvatures. Anterior between the lesser and greater curvatures is the anterior surface, while posterior is the posterior surface.