parts of stomach
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Parts of the Stomach
The stomach is a J-shaped muscular organ of the digestive tract, continuous with the esophagus above and the duodenum below. It holds approximately 30 mL at birth and 1.5-2 L in adulthood. Anatomically, it is divided into 4 main regions.
1. Cardia
- The small region immediately surrounding the esophagogastric junction
- Contains cardiac glands lined with columnar epithelium (distinct from the squamous epithelium of the esophagus)
- Cardiac glands contain mucous, endocrine, and undifferentiated cells, but notably lack parietal and chief cells
- Part of the oxyntic gland area (functionally)
2. Fundus
- The dome-shaped, most superior portion of the stomach, projecting upward above the esophagogastric junction
- Lies in contact with the left hemidiaphragm above and the spleen to the left
- Blood supply mainly from the vasa brevia (short gastric arteries) off the splenic artery
- Contains oxyntic glands with parietal cells and chief cells
- Functions as the reservoir for swallowed air (gas bubble visible on imaging)
3. Body (Corpus)
- The largest portion of the stomach, immediately below and continuous with the fundus
- Extends down to the incisura angularis - a fixed sharp indentation two-thirds of the way down the lesser curvature
- Contains the majority of parietal (oxyntic) cells - secrete HCl via the H+/K+-ATPase proton pump
- Contains chief cells in gastric crypts - secrete pepsinogen (converted to active pepsin in acidic conditions)
- Contains enterochromaffin-like (ECL) cells throughout, which produce histamine - a key driver of acid secretion
- D cells producing somatostatin are also present (negative regulatory role)
4. Antrum (Pyloric Antrum)
- Extends from its indistinct border with the body to the pyloric junction
- The border with the body lies roughly at the incisura angularis on the lesser curvature
- Contains predominantly G cells that secrete gastrin (stimulates acid production)
- Contains pyloric glands (mucous secreting, no parietal or chief cells)
- Contains the "antral pump" - smooth muscle that mixes food and controls gastric emptying
5. Pylorus
- A tubular structure joining the stomach to the duodenum, located ~2 cm to the right of midline at L1
- Contains the pyloric sphincter - the palpable circular muscle that controls gastric emptying
- Regulates the release of chyme from the stomach into the duodenum
Curvatures
| Structure | Description |
|---|---|
| Lesser curvature | Right upper border; site of gastroheaptic ligament (lesser omentum) |
| Greater curvature | Left lower border; longer; gives attachment to gastrocolic, gastrosplenic, and gastrophrenic ligaments |
| Incisura angularis | Sharp notch on the lesser curvature marking body-antrum junction |
Functional Zones (Glandular)
| Zone | Regions | % of Stomach | Gland Type |
|---|---|---|---|
| Oxyntic gland area | Cardia, Fundus, Corpus | ~75-85% | Oxyntic glands (parietal + chief cells) |
| Pyloric gland area | Antrum, Pylorus | ~15-25% | Pyloric glands (mucous + G cells) |
Key Cell Types by Region
| Cell | Location | Secretion | Function |
|---|---|---|---|
| Parietal (oxyntic) cells | Body/fundus glands | HCl + Intrinsic Factor | Digestion; B12 absorption |
| Chief (zymogenic) cells | Base of oxyntic glands | Pepsinogen I & II | Protein digestion (as pepsin) |
| G cells | Antral mucosa | Gastrin | Stimulates acid secretion |
| ECL cells | Body | Histamine | Amplifies acid secretion |
| D cells | Throughout | Somatostatin | Inhibits acid secretion |
| Surface mucous cells | Entire stomach surface | Mucus | Mucosal protection |
Blood Supply (Summary)
- Lesser curvature: Left gastric artery (celiac axis) + Right gastric artery (common hepatic)
- Greater curvature: Right gastroepiploic artery (gastroduodenal) + Left gastroepiploic artery (splenic)
- Fundus: Vasa brevia / short gastric arteries (splenic artery)
Sources: Sleisenger & Fordtran's Gastrointestinal and Liver Disease, Bailey & Love's Short Practice of Surgery 28th Ed., Yamada's Textbook of Gastroenterology 7th Ed.
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