The duodenum is the first small intestine section after the stomach. Read more about the duodenal function and anatomy here!


Of the Duodenum is the first section of the small intestine. It begins at the exit of the stomach (pylorus) and, after about 25 to 30 centimeters, passes into the jejunum, the second small intestine section. The duodenum performs important digestive work and provides hormones and other messengers. Its name is the duodenum of its length: about twelve fingers wide. Read all about the duodenum!

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  • What is the duodenum?

  • What is the function of the duodenum?

  • What problems can the duodenum cause?

What is the duodenum?

The duodenum (duodenum) is the beginning of the intestinal system and the first section of the small intestine. It is sharply demarcated from the stomach outlet (pylorus), about 25 to 30 centimeters long and has the form of a C, in whose round side the head of the pancreas (pancreas) lies.

The initial area of ​​the duodenum is the approximately five centimeters long and horizontally extending leg (pars superior). It has an extended beginning and an almost smooth surface inside.

Then follows the descending limb (Pars descendens) of the duodenum, whose inner surface is enlarged by numerous folds (Kerckring wrinkles) and contains the so-called Brunner glands (Duodenaldrüsen). In this area, the ducts of the large digestive glands enter the duodenum: the main bile duct (which leads the bile from the liver or gallbladder to the duodenum) as well as the pancreatic duct, which transports the pancreatic secretion.

At the end of the C, another horizontal part (pars horizontalis or pars inferior) follows, which then merges into a rising part (pars ascendens), at the end of which the second part of the small intestine, the jejunum, begins.

What is the function of the duodenum?

The duodenal function consists in the continuation of the digestive process begun in the mouth and stomach by enzymes: These originate from the pancreas and the duodenal glands.

Both gland secretions contain digestive enzymes as well as bicarbonate: it increases the pH of the chyme, which - when it enters the duodenum from the stomach - is highly acidic. For the enzymes to become active, the acidity must be reduced by bicarbonate.

The bile introduced into the duodenum is also important for digestion: the bile acids it contains are necessary for fat digestion.


In the duodenum also different enterohormones are formed and secreted:

  • Gastrin stimulates the production and secretion of gastric acid and pancreatic secretions.
  • Secretin stimulates bicarbonate production.
  • Cholecystokinin promotes the secretion of pancreatic enzymes and bile acids for fat digestion.

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What problems can the duodenum cause?

A megaduodenum is a permanent enlargement of the duodenum that may be innate or acquired.

Duodenal diverticulum are protuberances of the intestinal wall in the region of the duodenum. They are almost always found on the inner side of the curve and rarely cause discomfort.

Inflammation of the duodenum (duodenitis) can lead to duodenal ulcer (duodenal ulcer, duodenal ulcer).

The passage through the Duodenum may be affected by a congenital or acquired narrowing. Doctors here speak of a duodenal stenosis.

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