Anatomy of the Stomach

The Stomach

• The stomach is a J-shaped intraperitoneal organ located between the esophagus and the duodenum, responsible for accumulating and digesting food.
• It lies in the superior aspect of the abdomen, primarily in the epigastric and umbilical regions, and its exact size, shape, and position can vary from person to person and with position and respiration.

Gross Features

• The stomach is covered and connected to other organs by the peritoneum.
• The lesser omentum connects the stomach to the liver and extends around the stomach.
• The greater omentum continues inferiorly from the stomach, hanging from it like a curtain.
• The stomach has anterior relations with the diaphragm, liver (left lobe), and anterior abdominal wall.
• Posteriorly, it relates to the omental bursa (lesser sac), pancreas, left kidney and adrenal gland, spleen, and splenic artery.
• Superiorly, it relates to the esophagus and diaphragm, and inferiorly, it relates to the transverse mesocolon.

Parts of the Stomach

• The stomach has four main parts: cardia, fundus, body, and pylorus.
• The cardia surrounds the superior opening, cardiac orifice of the stomach at the T11 level.
• The fundus is the rounded, often gas-filled portion superior to and left of the cardia.
• The body is the largest and central portion inferior to the fundus.
• The pylorus connects the stomach to the duodenum and is divided into the pyloric antrum, pyloric canal, and pyloric sphincter.

Curvatures and Features

• The stomach has two unequal curvatures, creating a J-shape: the longer and convex greater curvature on the left, and the shorter and concave lesser curvature on the right.
• The greater curvature starts from the cardiac notch and contains a small notch called the angular incisure.
• The stomach has four histological layers: mucosa, submucosa, muscularis externa, and serosa.
• The mucosa has a wrinkled appearance, consisting of ridges called gastric folds, or rugae.

Blood Supply

• The arterial supply to the stomach comes from the celiac trunk and its branches.
• The right and left gastric arteries form anastomoses along the lesser curvature.
• The right and left gastro-omental arteries (gastroepiploic) form anastomoses along the greater curvature.
• The veins of the stomach run parallel to the arteries.

Nerve Supply

• The stomach receives nerve supply from the autonomous nervous system (ANS).
• Parasympathetic nerve supply arises from the anterior and posterior vagal trunks, derived from the right and left vagus nerve.
• Sympathetic nerve supply arises from the T5-T12 spinal cord segments and passes to the celiac plexus via the greater splanchnic nerve.

Lymphatic Drainage

• The lymphatic drainage of the stomach varies in individuals but generally involves the same regional lymph nodes.
• The nodes involved include juxtacardial nodes, gastric nodes, short gastric nodes, gastroomental nodes, and pyloric nodes.
• These nodes drain into the celiac nodes, which are then drained through the intestinal lymphatic trunk into the cisterna chyli (if present) and flow into the thoracic duct.

Clinical Correlations

• Hiatal Hernia: a protrusion of part of the stomach into the mediastinum through the esophageal hiatus of the diaphragm, often caused by trauma, congenital malformations, or previous surgery, but most commonly due to advanced age.
• Gastro-Oesophageal Reflux Disease: a digestive disorder affecting the lower oesophageal sphincter, causing the movement of gastric acid and food into the esophagus, often due to dysfunction of the lower oesophageal sphincter, delayed gastric emptying, or Hiatal hernia.