Normal anatomy

The pancreas is 12-15 cm long, 3-6 cm wide and 2-4 cm thick, weighs 65-70 g and is situated transversely in the upper part of the retroperitoneal space. The organ is surrounded by a layer of fat of varying thickness. The head lies adjacent to the duodenal loop to the right of the midline, and the uncinate process extends behind the superior mesenteric vessels. The body runs in a shallow S-shaped loop up to the left, the tail extending to the hilum of the spleen. The drainage duct of the exocrine pancreas, the duet of Wirsung opens together with the choledochal duct in the major papilla in the middle of the second part of the duodenum. The secondary duct, the duet of Santorini, opens into the minor papilla approximately 2-3 cm above the major papilla. An awareness of the retroperitoneal location of the pancreas is important to a proper understanding of the secondary effects of pancreatic diseases.

Anatomical variants of the pancreas include the pancreas divisum, where the dorsal and ventral parts of the pancreas have not united; pancreas annulare, where the head of the pancreas encircles, and often causes narrowing of the duodenum and accessory pancreatic islands.

David J. Allison and Carl-Gustaf Standertskjold-Nordenstam