Anatomy of the Stomach

Introduction

Stomach: Expanded part of the digestive tract between esophagus and duodenum.
Function: Accumulates ingested food, prepares it chemically and mechanically for digestion and passage into the duodenum. Acts as a food blender and reservoir, enabling enzymatic digestion of carbohydrates, proteins, and fats.

Lies obliquely in the upper and left part of the abdomen, occupying the epigastric, umbilical, and left hypochondriac regions.
Size: Approximately 25 cm long in adults.
Capacity: 30 ml at birth, 1 liter at puberty, 1.5 to 2 liters or more in adults.

Orifices: Cardiac orifice (superior, joined by esophagus) and pyloric orifice (inferior, opens into duodenum).
Parts: Divided into cardiac part (fundus and body) and pyloric part (pyloric antrum and pyloric canal).
Fundus: Dilated superior part above the cardiac orifice, related to the left dome of the diaphragm.
Body: Major part between fundus and pyloric antrum, contains gastric glands with mucous cells, chief cells, and parietal cells.

Lesser Curvature: Short concave right border, providing attachment to the lesser omentum.
Greater Curvature: Longer convex left border, gives attachment to greater omentum, gastrosplenic, and gastrophrenic ligaments.

Peritoneal Relations: Lined on both surfaces by peritoneum, forming lesser and greater omentum and gastrosplenic ligament.
Visceral Relations: Anteriorly related to diaphragm, left lobe of liver, transverse colon, and anterior abdominal wall; posteriorly to omental bursa and pancreas.

Formed by structures in the supine position: left dome of diaphragm, spleen, left kidney and suprarenal gland, splenic artery, pancreas, and transverse mesocolon.

Arterial Supply: Lesser curvature (left and right gastric arteries), greater curvature (gastroepiploic arteries), fundus (short gastric arteries).
Venous Drainage: Portal vein, splenic vein, superior mesenteric vein.
Lymphatic Drainage: Celiac nodes, pancreaticosplenic nodes, gastroepiploic nodes, and hepatic nodes.
Nerve Supply:
- Sympathetic: T6 to T10 segments via greater splanchnic nerves, providing vasomotor, motor, and pain functions.
- Parasympathetic: Anterior and posterior vagal trunks, enhancing motility, peristalsis, and gastric juice secretion.

Mucosa: Contains gastric folds (rugae), gastric pits, and glands.
Submucosa: Made of connective tissue with arterioles and nerve plexus.
Muscle Coat: Longitudinal fibers, inner circular fibers forming pyloric sphincter, and oblique fibers.
Serous Coat: Consists of peritoneal covering.

Acts as a reservoir and food blender, mixing food with gastric juices by peristaltic movements.
Contains enzymes for digestion and aids in absorption of vitamin B12.

Mucous Membrane: Simple columnar epithelium at the cardiac end, gastric glands at fundus/body, and pyloric glands in the pyloric part.
Submucosa: Loose connective tissue with Meissner's plexus.
Muscularis Externa: Outer longitudinal, inner circular fibers, and innermost oblique layers.
Serosa: Single layer of squamous cells.

Developed as a fusiform dilation from the foregut in the fourth week of embryonic life, with subsequent rotations and transformations forming the mature structure.

Congenital Hypertrophic Pyloric Stenosis: Thickening of the pylorus, causing vomiting in infants.
Peptic Ulcer: Erosion of the stomach lining, often caused by H. pylori, stress, or excessive acid. Symptoms include epigastric pain, indigestion, nausea, vomiting, weight loss, and bleeding. Treatment may involve antacids, partial gastrectomy, or vagotomy.