Anatomy, Normal Variations, and Relations of Stomach
The stomach is an enlarged reservoir of the proximal digestive tract, in which ingested food is soaked in gastric juice containing enzymes and hydrochloric acid and then released spasmodically into the duodenum by gastric peristalsis. The form and size of the stomach vary considerably, depending on the position of the body and the degree of filling.
The stomach has anterior and posterior walls that practically touch when the organ is empty and flattened. It is distended inferiorly and to the left, creating a convex greater curvature and a concave lesser curvature along its superior border. The superiormost region of the greater curvature includes the fundus of the stomach, a domed section on the superior left side of the abdomen, which is closely related to the diaphragm and spleen. The greater and lesser curvatures meet at the cardiac region of the stomach, where the esophagus enters. On the right the esophagus continues smoothly into the lesser curvature, but on the left there is a definite indentation, the cardial notch (incisure), which becomes most obvious when the fundus is full and bulges superiorly. The largest region of the stomach is the body (corpus) of the stomach, located inferior to the cardiac region and fundus. The massiveness of the greater curvature causes the stomach’s lumen to shift to the right side of the abdomen, where it will empty into the duodenum. Prior to its terminus, the body of the stomach blends imperceptibly into the pyloric part, except along the lesser curvature, where the angular incisure (notch) marks the boundary between the body and the pyloric part. The latter contains the pyloric antrum, which narrows into the pyloric canal, terminating at the pyloric valve.
The surface of the stomach is entirely covered and suspended by peritoneum. A double layer of peritoneum, deriving from the embryonic ventral mesentery, extends from the lesser curvature and first part of the duodenum toward the liver. This is the lesser omentum, and it may be subdivided into a larger, thinner, hepato- gastric ligament and a smaller, thicker, distal hepatoduodenal ligament, which attaches to the pyloric region and to the upper horizontal portion of the duodenum. The portal vein, proper hepatic artery, and common bile duct are found within the hepatoduodenal ligament. The free edge of the hepatoduodenal ligament, located on the right end of the lesser omentum, forms the anterior border of the omental (epiploic) foramen (of Winslow), which gives access to the omental bursa (lesser sac) located posterior to the stomach. The greater omentum, a derivative of the embryonic dorsal mesentery, passes inferiorly from the greater curvature and contains, between its two frontal and two dorsal sheets, the inferior recess of the omental bursa. Typically this space is negligible and the entire greater omentum can be moved like a single apronlike object hanging from the greater curvature.
The anterior surface of the stomach contacts the peritoneum lining the anterior abdominal wall, the inferior surface of the left lobe of the liver, and, to some extent in the pyloric region, the quadrate lobe of the liver and the gallbladder. Its posterior surface is in apposition with retroperitoneal structures (pancreas, splenic vessels, left kidney, and adrenal gland) from which, however, it is separated by the omental bursa. The fundus of the stomach bulges against the left diaphragmatic dome. On the left, adjacent to the fundus, is the spleen, which is connected to the stomach by the gastrosplenic ligame also derived from the embryonic dorsal mesentery.