Endoscopic signs of a normal stomach

The stomach is located in the epigastrium. The lesser curvature of the stomach, being a continuation of the esophagus, descends to the left of the midline, along the XI and XII thoracic vertebrae, then, curving to the right, crosses the aorta and passes into the pylorus. The greater curvature rises above the esophagus by 4-5 cm. Having reached the diaphragm, it repeats its dome, and then, bending in an arc, goes down and to the right to the pylorus.

The stomach is located with its greater mass to the left of the midline, and only the pylorus extends 2-3 cm to the right. Only the entrance to the stomach and the pylorus are firmly fixed. The position of the fundus and the greater curvature changes depending on the filling of the stomach. When lowered, the stomach can reach the navel and below.

Stomach shapes

1. Horn-shaped.
2. Hook-shaped - the most common.
3. Long stomach (stocking shape).

The stomach has anterior and posterior walls, greater and lesser curvature. The anterior wall is always more elongated than the posterior. The entrance to the stomach is the cardia, the exit is the pylorus.

Sections of the stomach.

• Cardiac.
• Bottom (vault).
• Body of the stomach:
  • upper third,
  • middle third,
  • lower third.
• Pyloric:
  • antrum,
  • gatekeeper channel.

The cardiac section is 4 cm around the cardia. It begins with the opening through which the stomach communicates with the esophagus - the cardiac opening.

The fundus (vault) is the uppermost section of the stomach, from 2 to 7 cm high. It is located directly to the left of the cardiac part.

The body is the largest part of the stomach, which continues upwards into the fundus without sharp boundaries, and to the right, gradually narrowing, passes into the pyloric part. The boundary between the pyloric part and the body of the stomach passes along the intermediate groove, which on the lesser curvature corresponds to the angular notch (incisura angularis).

The pyloric section is directly adjacent to the pyloric opening , through which the lumen of the stomach communicates with the lumen of the duodenum. The pyloric section is subdivided into the pyloric cave, antrum pyloricum, and the pyloric canal, canalis pyloricus, equal in diameter to the adjacent duodenum, and the pylorus itself .

The angle of the stomach at the border of the body and the pyloric part along the lesser curvature is distinguished separately, as well as the angle of His - the angle at which the esophagus enters the stomach. The latter is usually 90° (81°), and in 19% it is from 90° to 180°.

The shape and size of the stomach vary depending on the amount of contents, functional state, and diet. The shape and position of the stomach are also affected by constitutional and age factors, pathological processes in the abdominal cavity, and the position of the diaphragm. The length of the stomach is on average 14-30 cm (usually 20-25 cm), the width is 10-16 (12-24) cm, the length of the lesser curvature is 10.5-24.5 (18-19) cm, the length of the greater curvature is 32-64 (45-56) cm. The capacity of the stomach is from 1.5 to 2.5 liters, in men the capacity is greater than in women.

Histological structure:

• Mucous membrane:
  • single-layer columnar epithelium,
  • lamina propria of the mucous membrane (loose connective tissue),
  • muscularis mucosa.
• Submucosal layer.
• Muscular layer.
• Serous membrane.

The gastric mucosa is a continuation of the esophageal mucosa. A clearly distinguishable serrated strip represents the border between the epithelium of the esophageal and gastric mucosa. At the level of the pylorus, corresponding to the position of the sphincter, the mucosa forms a permanent fold. The gastric mucosa is 1.5-2 mm thick; it forms numerous folds, mainly on the posterior wall of the stomach. The folds have different lengths and different directions: near the lesser curvature, there are long longitudinal folds that delimit a smooth area of the mucosa in the area of the lesser curvature - the gastric canal, canalis ventricularis, which mechanically directs the food bolus into the pyloric cave. In other areas of the stomach wall, the folds have a variety of directions, with longer folds connected by shorter ones. The direction and number of longitudinal folds are more or less constant. When the stomach is stretched, the folds of the mucosa are smoothed out.

The mucous membrane of the stomach has its own muscular plate, which is separated from the muscular layer of the stomach by a well-developed, loose submucous layer . Together with its own muscular plate, it causes the formation of folds.

The mucous membrane of the stomach is divided into small, 1-6 mm in diameter, areas - gastric fields. On the fields there are depressions - gastric pits , having a diameter of 0.2 mm. In each pit, openings of 1-2 ducts of the gastric glands open, located in the proper plate of the mucous membrane. A distinction is made between gastric (proper) glands, cardiac glands, and pyloric glands. Proper glands predominate. They are located in the body and fundus of the stomach and contain 4 main types of cells:

• main (glandular),
• parietal (lining),
• mucous (accessory),
• cervical.

The main cells produce pepsinogen. The parietal cells are located outside the main cells, they produce hydrochloric acid. The accessory cells produce mucoid secretion. The cervical cells are the center of regeneration of the secretory apparatus of the glands. The proper glands of the stomach contain argentophilic cells, they are related to the production of the internal antianemic factor (Castle factor). The cardiac and pyloric glands produce mucus.

The muscular layer of the stomach consists of two layers: circular and longitudinal, as well as oblique fibers.

The circular layer is a continuation of the circular layer of the esophagus. It is a continuous layer that envelops the stomach along its entire length. The circular layer is expressed somewhat less strongly in the area of the bottom; at the level of the pylorus, it forms a significant thickening - the pyloric sphincter.

The outer, longitudinal layer, which is a continuation of the eponymous layer of the esophagus, is thickest in the area of the lesser curvature. At the point where the body passes into the pyloric part (incisura angularis), its fibers fan out along the anterior and posterior walls of the stomach and are woven into the bundles of the next (circular) layer. In the area of the greater curvature and the bottom of the stomach, the longitudinal muscle bundles form a thinner layer, but occupy a wider area.

Inside the circular layer are oblique fibers. These bundles do not form a continuous layer, but form separate groups; in the region of the entrance to the stomach, the bundles of oblique fibers loop around it, passing to the anterior and posterior surfaces of the body. Contraction of this muscle loop causes the presence of the cardiac notch (angle of His). Near the lesser curvature, the oblique bundles take a longitudinal direction.

The serous membrane is the visceral layer of the peritoneum and covers the stomach on all sides.

Blood supply to the stomach.The blood supply to the stomach is provided by branches of the celiac trunk - the left gastric, hepatic and splenic arteries. The left gastric artery passes along the free right edge of the gastropancreatic ligament and divides into ascending and descending branches. The descending branch of the left gastric artery on the lesser curvature joins with the right gastric artery, which branches off from the hepatic artery. The third source of blood supply to the stomach is the splenic artery, from which short gastric arteries branch off, going in the gastrosplenic ligament to the fundus of the stomach. The final branch of the splenic artery is the left gastroepiploic artery, passing along the greater curvature in the gastrocolic ligament. It joins with a similar branch coming from the right of the hepatic artery - with the right gastroepiploic artery. Due to the very pronounced arterial collateral network, sufficient blood supply to the stomach is provided by one large gastric artery.

The veins of the stomach follow the arteries of the same name and flow into the portal vein. In the cardiac region, the veins of the stomach anastomose with the lower veins of the esophagus. In portal hypertension, these anastomoses are often a source of bleeding.

Innervation of the stomach.The stomach is innervated by sympathetic and parasympathetic fibers, which form extragastric nerves and intramural plexuses. Sympathetic nerves extend to the stomach from the celiac plexus and accompany the vessels extending from the celiac artery. They reduce peristalsis, cause contraction of the pylorus, constrict the vessels and transmit the feeling of pain. Parasympathetic innervation of the stomach is carried out by the vagus nerves, as well as nerves that go as part of the celiac plexus. They increase peristalsis of the stomach, secretion of glands, relax the pyloric sphincter, transmit the feeling of nausea and hunger. Intramural plexuses of the stomach are represented by the myenteric and submucous plexuses. The myenteric plexus plays an important role in the motor activity of the stomach. The submucous plexus is involved in the regulation of the secretory activity of the stomach.

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