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Stomach Overview

The stomach is a temporary storage tank in the GI tract, located in the upper left quadrant of the peritoneal cavity. It is responsible for further degrading food both physically and chemically, converting it into a slurry known as chyme, which is then delivered to the small intestine. An empty stomach can hold about 50 ml, while a distended one can accommodate up to 4 L of food.

Gross Anatomy

The adult stomach varies from 15 to 25 cm in length. It features major regions: the cardia, fundus, body, and pyloric part. The cardia surrounds the orifice where food enters. The fundus is dome-shaped, while the body is the midportion that leads into the funnel-shaped pyloric part, which has a wider pyloric antrum that narrows into the pyloric canal ending at the pylorus. The pylorus connects to the duodenum via the pyloric sphincter, which regulates stomach emptying.

Internal Anatomy

The stomach has longitudinal and circular muscular layers alongside an oblique layer in the muscularis externa. The interior features rugae, which are longitudinal folds that allow for stomach expansion.

Curvatures and Omenta

The stomach has a greater curvature (convex lateral surface) and a lesser curvature (concave medial surface). Two mesenteries, the lesser omentum and greater omentum, tether the stomach to surrounding organs. The lesser omentum connects the liver to the lesser curvature, while the greater omentum drapes over the small intestine, wrapping around the spleen and part of the large intestine, serving protective and immunological roles with fat deposits and lymph node collections.

Nervous and Vascular Supply

The stomach is innervated by the autonomic nervous system, where sympathetic fibers relay through the celiac ganglion and parasympathetic fibers are supplied by the vagus nerve. Its arterial supply comes from gastric and splenic branches of the celiac trunk, with venous drainage via the hepatic portal system.