Pancreas

Structure

The pancreas is a glandular organ having both exocrine and endocrine function. It lies in the retroperitoneum of the upper abdomen, traversing the midline usually diagonally upwards towards the hilum of the spleen.

The pancreas consists of four parts:

  • Head and uncinate process
  • Neck
  • Body
  • Tail

Parts of the Pancreas

Head

The head is the broadest part of the gland, filling the C-shaped concavity formed by D1–3. Posteriorly is the inferior vena cava (IVC) and the right and left renal veins at the L2 vertebral body level. The terminal part of the bile duct indents its posterior surface. The uncinate process of the head is the lower hook-shaped extension of the head which courses upwards and to the left, behind the superior mesenteric vein and artery.

Neck

This is the narrow band of tissue that lies in front of the commencement of the portal vein

Body

The body extends from the neck across and upwards towards the left. The important relations are the splenic vein, closely applied to the posterior surface and the IMV, which joins the splenic vein. The transverse mesocolon attaches along the anterior border and it therefore lies behind the lesser sac, forming part of the stomach bed.

Tail

This lies within the lienorenal ligament, thus reaching the hilum of the spleen

Ductal Structure of the Pancreas

The pancreatic duct arises from the pancreatic tail and receives numerous short tributaries entering at right angles. This duct drains into the duodenum via the ampulla of Vater and major duodenal papilla.

The anterior and superior portions of the pancreas are drained by the accessory duct of Santorini, either into the duodenum at minor papilla or into the main pancreatic duct. The minor papilla is often not patent as there may be partial or complete obliteration of the accessory duct.

Vascular Supply of the Pancreas

Arterial Supply

This arises from the coeliac axis and superior mesenteric artery. The head is supplied by the anterior and posterior-superior pancreaticoduodenal arteries. These are branches of the gastroduodenal artery, itself a branch of the hepatic artery.

The pancreatic body and tail are supplied by the dorsal pancreatic artery and superior pancreatic branches of the splenic artery, the largest of which is the arteria pancreatica magna.

Venous Drainage

The pancreatic head is drained by the pancreaticoduodenal veins. These veins may drain directly or indirectly into the portal vein.

The body and tail are drained by several small veins, emptying directly into the splenic vein. The splenic vein lies in a groove on the dorsal-superior margin of the pancreas. The splenic vein joins the superior mesenteric vein posterior to the neck to form the portal vein.

Lymphatic Drainage

Lymph nodes are distributed along the major vascular pathways. The neck, body and tail drain via the suprapancreatic and infrapancreatic lymphatic chains and splenic hilar nodes.

The head and neck drains into pancreaticoduodenal and juxtaaortic nodes and porta hepatis nodes.

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