Duodenum

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Duodenum . First portion of the small intestine , it joins the pylorus with the jejunum and takes its name because it is approximately 12 finger lengths long. It is the shortest, widest, and most fixed portion of the small intestine.

Summary

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  • 1 Features
  • 2 Function
  • 3 Parts that make it up
  • 4 Layers
  • 5 See also
  • 6 Sources

characteristics

It is the first and shortest part (25cm) of the small intestine , a “C” shaped path continues around the head of the pancreas .

It begins at the pylorus on the right side and ends at the duodenal junction on the left side. This union occurs approximately at the height of the L2 vertebra, 2-3cm to the left of the median line. The union, in general, takes the form of an acute angle, the duodenal flexion. Most of the duodenum is secured by the peritoneum to structures in the abdominal wall and is considered partially retroperitoneal.

Function

Its main function is the breakdown of food and absorption of nutrients. Practically 90% of the nutrients are absorbed in this segment and the remaining 10% in the jejunum and ileum .

Parts that make it up

It forms four angles of approximately 90 degrees, comprising four parts

  • Upper portion (first): short (5cm) and located anterolateral to the L1 vertebra. It ascends from the pylorus and is covered by the liver and gallbladder .
  • Descending (second) portion: the longest (7-10cm), descending along the lateral faces of the L1 to L3 vertebrae. It is directed downward, curving around the head of the pancreas.
  • Horizontal portion (third): 6-8cm in length. It runs transversely to the left, passing over the IVC, the aortaand the L3 vertebra. It is crossed by the superior mesenteric artery and vein and the root of the jejunum and ileum mesentery .
  • Ascending portion (fourth): short (5cm). It begins to the left of the L2 vertebra. it follows a path in a superior direction along the left side of the aorta until it reaches the lower edge of the pancreas.

Layers

Anatohistologically, the duodenum has 5 layers:

  • Serous tunic
  • Subserous fabric
  • Muscular tunic
  • Submucosa fabric
  • Mucous tunic

 

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