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Duodenum: anatomy, location and function

The duodenum is the first and shortest part of the small intestine, about 20 to 25 cm long and C-shaped. It receives chyme from the stomach, bile and pancreatic juices, and continues chemical digestion and absorption of iron and calcium.

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Highlighted in the model: Duodenum. Click any part to read about it, or switch off “Highlight topic” to see the whole body. 3D data: BodyParts3D, © The Database Center for Life Science, CC BY 4.0; meshes simplified and recoloured. The model is an adult male.

Duodenum at a glance

What it is
The duodenum is the first and shortest part of the small intestine, about 20 to 25 cm long and C-shaped.
Location
It runs from the pylorus at about L1 to the duodenojejunal flexure at about L2, curving around the head of the pancreas. The first 2 to 3 cm (duodenal cap) is intraperitoneal; the rest of part 1 and parts 2 to 4 are retroperitoneal.
Function
It receives chyme from the stomach, bile and pancreatic juices, and continues chemical digestion and absorption of iron and calcium.
Body system
Digestive · single, midline structure
FMA ID
FMA7206 (Foundational Model of Anatomy)

Key facts

  • Four parts: superior (L1), descending (L1 to L3), horizontal (L3) and ascending (L3 to L2).
  • The hepatopancreatic ampulla opens at the major duodenal papilla in the descending part.
  • Brunner glands in the submucosa secrete alkaline mucus.
  • Supplied by the gastroduodenal and pancreaticoduodenal arteries, from both the celiac trunk and the superior mesenteric artery.

Clinical relevance

Duodenal ulcers occur most often in the first part.

Structures next to the duodenum

The nearest named structures in the 3D model, measured from the centre of each part:

References

  1. Foundational Model of Anatomy: Duodenum (FMA7206). EMBL-EBI Ontology Lookup Service.
  2. OpenStax. Anatomy and Physiology 2e, §23.1 Overview of the Digestive System. Rice University, 2022.
  3. Mitsuhashi N. et al. (2009). BodyParts3D: 3D structure database for anatomical concepts. Nucleic Acids Research 37, D782–D785. Data © The Database Center for Life Science, CC BY 4.0.

Explore the whole body in the interactive 3D human anatomy model, or browse the A–Z list of human structures.