Overview
The duodenum is the first part of the small intestine (5-7 m), followed by the jejunum and ileum (in that order); it is also the widest and shortest (25 cm) part of the small intestine. The duodenum is a C-shaped or horseshoe-shaped structure that lies in the upper abdomen near the midline (see the image below).
Stomach and duodenum, coronal section.