- Duodenum: first, shortest, widest and most fixed part of the small intestine, 25 cm long, "C"-shaped, extending from the pylorus to the duodenojejunal flexure.
- Lies above the umbilicus opposite L1 to L3 vertebrae; retroperitoneal except the proximal 2.5 cm, which is suspended by the lesser omentum above and the greater omentum below.
Parts of the Duodenum
Parts of the duodenum
Part
First (superior)
- Length
- 5 cm
- Extent
- Pylorus to superior duodenal flexure at the neck of the gallbladder
Second (descending)
- Length
- 7.5 cm
- Extent
- Superior duodenal flexure down to inferior duodenal flexure, opposite L3
Third (horizontal)
- Length
- 10 cm
- Extent
- Inferior duodenal flexure, horizontally left across L3, in front of the inferior vena cava (IVC)
Fourth (ascending)
- Length
- 2.5 cm
- Extent
- Upward left of the aorta to the duodenojejunal flexure at the upper border of L2