Duodenum

Duodenum, dodecadactylon (from Greek "Δωδεκαδάχτυλο" - from Ancient Greek physician Herophilos who measured it to be twelve (dodeka) fingers (dactylon) long)
Schematic diagram of the gastrointestinal tract, highlighting the duodenum.
Details
Precursor	Foregut (1st and 2nd parts), Midgut (3rd and 4th part)
Artery	Inferior pancreaticoduodenal artery, Superior pancreaticoduodenal artery
Vein	Pancreaticoduodenal veins
Nerve	celiac ganglia, vagus
Identifiers
Latin	Intestinum duodenum
MeSH	A03.556.124.684.124
Dorlands /Elsevier	Duodenum
TA	A05.6.02.001
FMA	7206
Anatomical terminology []

The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear, and the terms anterior intestine or proximal intestine may be used instead of duodenum. In mammals the duodenum may be the principal site for iron absorption.

The duodenum precedes the jejunum and ileum and is the shortest part of the small intestine, where most chemical digestion takes place.

In humans, the duodenum is a hollow jointed tube about 25–38 cm (10–15 inches) long connecting the stomach to the jejunum. It begins with the duodenal bulb and ends at the suspensory muscle of duodenum. It can be divided into four parts.

The duodenum is a 25–38 cm C-shaped structure lying adjacent to the stomach. It is divided anatomically into four sections. The first part of the duodenum lies within the peritoneum but its other parts are retroperitoneal.

The first part, or superior part, of the duodenum is a continuation from the pylorus. It is superior to the rest of the segments, at the vertebral level of L1. The duodenal bulb about 2 cm long, is the very first part of the duodenum and is slightly dilated. The duodenal bulb is a remnant of the mesoduodenum, a mesentery which suspends the organ from the posterior abdominal wall in fetal life. The first part of the duodenum is mobile, and connected to the liver by the hepatoduodenal ligament of the lesser omentum. The first part of the duodenum ends at the corner, the superior duodenal flexure.