Superior part of duodenum

The superior part of duodenum (a.k.a. the first part of duodenum, D1) is the shortest and most mobile segment of the duodenum, measuring approximately 5 cm in length. It begins at the pylorus and extends postero-laterally to the right, terminating at the superior duodenal flexure, which lies immediately below the neck of the gallbladder at the level of the L1 vertebra. Owing to its close anatomical relationship with the gallbladder, the superior part is often found to be bile-stained on post mortem examination.

Peritoneal attachments of the superior part of duodenum

The superior part is unique among the four parts of the duodenum because its proximal portion is intraperitoneal and freely mobile. It is almost completely invested by peritoneum, although a small area of its posterior surface near the inferior vena cava and the neck of the gallbladder remains uncovered. The hepatoduodenal ligament, containing the structures of the portal triad, is attached to the upper border of the proximal part, while the greater omentum is attached to its lower border.

Relations of superior part of duodenum

Clinical correlates

• The proximal 2 cm forms the duodenal bulb (ampulla), a common site for peptic ulceration. Posterior duodenal ulcers may erode the gastroduodenal artery, causing severe upper gastrointestinal haemorrhage.

• Its close relationship to the common bile duct, portal vein, and gallbladder is important during hepatobiliary and pancreatic surgery.