Stomach

The stomach is a muscular organ that lies between the esophagus and duodenum in the upper abdomen. It lies on the left side of the abdominal cavity caudal to the diaphragm at level of T10.

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

  • cardia: the area that receives the esophagus (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, located on the right of the midline at level of L1.

There are two smooth muscle sphincters, esophageal 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 celiac 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
  • fornix gastricus: refers to the arch-shaped superior margin of the fundus of the stomach
  • left and right gastric veins drain to portal vein
  • short gastric vein and left gastroepiploic vein drain to splenic vein
  • right gastroepiploic vein drains to superior mesenteric vein 3

Routes of the flow of lymph from perigastric nodes to para-aortic lymph nodes include 4-6

Nomura et al suggested that the most likely route for para-aortic lymph node metastases was from the left gastric artery nodes passing by the celiac artery 4.

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 hydrochloric acid (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 distension of the antrum, and digestive products; inhibited by a pH normally <4 (acidic), 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 visualized 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.

Analogous to the abovementioned histological architecture, the gastric walls will consist of five concentric layers of alternating echodensity when viewed with an appropriately high frequency transducer, characteristic of the sonographic gut signature 16.

Sonographic localization of the stomach is typically performed with epigastric transducer placement with the patient in a supine or right lateral decubitus position. The gastric antrum is commonly visualized just to the right of anatomic midline using the following sonographic landmarks; 11

Visualization of the gastric body is often possible by sweeping leftward of the gastric antrum. Visualization of the gastric fundus may require using the spleen as a sonographic window, using a left intercostal probe position.​ The sonographic appearance of the stomach, most notably the gastric antrum, may differ based on the patient's prandial status as follows;

  • fasting patient
    • gastric antrum may apper as a flattened ovoid with absent to minimally appreciable luminal contents 11
      • targetoid or "bulls eye" appearance 12
    • may also appear round, with homogenous anechoic fluid filling the lumen
  • post-prandial patient
    • viscous fluid ingestion results in luminal contents appearing uniformly hyperechoic 
    • recent solid food ingestion results in a heterogenous apperance of luminal contents, with posterior acoustic shadowing
      • may be indicative of higher aspiration risk for patients under general anesthesia 10
Anatomy: Abdominopelvic
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Article information

rID: 5637
Section: Anatomy
Synonyms or Alternate Spellings:
  • Cardia of the stomach
  • Gastric cardia
  • Gastrum

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Cases and figures

  • Figure 1
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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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