Location
The stomach is located in the epigastric, umbilical, and left hypochondriac regions of the abdomen. It lies just below the diaphragm and forms a major part of the upper gastrointestinal tract.
Size and Capacity
At birth, the stomach measures about 25 cm in length and has a capacity of approximately 1 ounce (30 ml). By puberty, it can hold around 1 litre of content, and in adults, its capacity increases to between 1.5 to 2 litres.
External Features
The stomach has two orifices: the cardiac orifice, located at the T11 vertebral level where the oesophagus enters the stomach, and the pyloric orifice, located at the L1 vertebral level leading into the duodenum. It also has two curvatures: the lesser curvature on the right side and the greater curvature on the left side. There are two surfaces — the anterior or anterosuperior surface and the posterior or posteroinferior surface.
Parts of the Stomach
The stomach is divided into two main parts: the cardiac part and the pyloric part.
- The cardiac part includes the fundus and body. It contains mucous cells for mucus secretion, chief cells (also called peptic or zymogenic cells) that secrete digestive enzymes, and parietal cells (or oxyntic cells) responsible for the secretion of hydrochloric acid (HCl).
- The pyloric part includes the pyloric antrum and pyloric canal, which lead into the duodenum and regulate gastric emptying.
Blood Supply
The arterial supply to the stomach is rich and includes several branches:
- Along the lesser curvature, it is supplied by the left gastric artery and right gastric artery.
- Along the greater curvature, it is supplied by the right gastroepiploic and left gastroepiploic arteries.
- The fundus of the stomach receives blood from 5 to 7 short gastric arteries.
Venous drainage is primarily through the portal vein, superior mesenteric vein, and splenic vein, which drain the deoxygenated blood from the stomach.
Lymphatic Drainage
Lymphatic drainage of the stomach is divided according to its regions:
- The upper part of the left one-third drains into pancreaticosplenic lymph nodes.
- The right two-thirds of the stomach drain into left gastric nodes.
- The lower part of the left one-third drains into right gastroepiploic nodes.
- The pyloric part drains into the subpyloric nodes.
Eventually, all lymph from the stomach drains into the coeliac lymph nodes.
Nerve Supply
The stomach receives both sympathetic and parasympathetic innervation:
- The sympathetic nerves originate from spinal cord segments T6 to T10 and reach the stomach via the greater splanchnic nerves, coeliac plexus, and hepatic plexus.Sympathetic nerves are vasomotor, stimulate the pyloric sphincter, and inhibit the rest of the gastric musculature.
- The parasympathetic nerves are derived from the vagus nerves (vagi). They are motor and secretomotor to the stomach muscles and glands, and inhibitory to the Pyloric sphincter.
Clinical Anatomy
Gastric carcinoma is commonly found along the greater curvature of the stomach and is a serious malignant condition. Gastric ulcers are more frequently located along the lesser curvature and are often associated with individuals who are under chronic stress, in a hurry, worried frequently, and consume spicy foods — often summarized as people who are “in a hurry, mostly worried, and eat spicy curry.”