Stomach

The stomach lies between the oesophagus and duodenum in the upper abdomen. It lies on the left side of the abdominal cavity caudal to the diaphragm.

The stomach (normal volume 45 mL) is divided into distinct regions:

  • cardia: the area that receives the oesophagus (gastro-oesophogeal junction)
  • fundus: formed by the upper curvature
  • body (corpus): the main central region of the organ
  • pylorus (antrum): the lower section of the stomach that facilitates emptying into the small intestine

There are two smooth muscle sphincters, oesophageal and pyloric, that dictate entry into and exit from the stomach. These are under the control of several mechanisms including stimulant (parasympathetic) and inhibitory (orthosympathetic) control from the anterior gastric, posterior, superior and inferior coeliac and myenteric nerve plexuses.

The inner mucosal surface has many rugal folds that act to increase the surface area of the stomach lining and increase its efficiency.

  • incisura angularis: small anatomical notch on the stomach located on the lesser curvature of the stomach near the pyloric end

Lymphatics drain with arteries to the coeliac lymph nodes.

Akin to other areas of the gastrointestinal (GI) tract, the stomach walls are composed of the following layers:

  • mucosa: internal layer of epitelium, the lamina propria (loose connective tissue and gastric glandular tissue) and the muscularis mucosae
  • submucosa: a fibrous layer of connective tissue under the mucusa
  • muscularis externa: this is the muscular layer of the stomach wall, but differs from other GI organs (which have two layers); there are three layers (inner oblique, middle circular and outer longitudinal)
  • serosa: the outermost layer of the stomach wall consisting of connective tissue which is continuous with the peritoneum

The stomach wall contans several different types of glandular tissue. The cardia, fundus and pylorus all have different types of glands and are composed of a variety of different cells:

  • mucous cells: secrete a mucus gell layer and are found throughout the stomach
  • parietal (oxyntic) cells: secrete gastric acid and intrinsic factor throughout the stomach
  • chief (zymogenic) cells: secrete pepsinogen and rennin in the fundus only
  • enteroendocrine (APUD) cells: secrete a variety of products and are found throughout the stomach

Control of the stomach relates to the autonomic nervous system and various digestic system hormones:

  • gastrin: causes an increase in the secretion of HCl, pepsinogen and intrinsic factor from parietal cells in the stomach; it also causes increased motility in the stomach; released by G-cells in the stomach to distenstion of the antrum, and digestive products; inhibited by a pH normally less than 4 (high acid), as well as the hormone somatostatin
  • cholecystokinin (CCK): greatest effect on the gall bladder, but it also decreases gastric emptying and increases release of pancreatic juice which is alkaline and neutralizes the chyme
  • secretin: has most effects on the pancreas, but will also diminish acid secretion in the stomach
  • gastric inhibitory peptide (GIP): decreases both gastric acid and motility
  • enteroglucagon: decreases both gastric acid and motility
  • glycogen: produced in the brain and stomach, affects the liver and level of glucose in the stomach

The stomach is not usually well visualised  on the plain film although a gastric bubble (gas outlining the fundus of the stomach) is often visible on an erect chest or abdominal x-ray.

The stomach wall should be from 2 to 5mm thick, except at the gastro-esophageal junction.

Abdominal and pelvic anatomy
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Article information

rID: 5637
Section: Anatomy
Tags: cases, cases
Synonyms or Alternate Spellings:
  • Gastrum

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Cases and figures

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    Figure 2: histology
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    Figure 3: histology (high power)
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    Normal small bowe...
    Case 1: stomach outlined on fluoroscopy
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    The fine reticula...
    Case 2: areae gastricae in a gastric antrum
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