The Pancreas - Anatomy - Duct System - Vasculature (2024)

The pancreas is an abdominal glandular organ with both digestive(exocrine) andhormonal (endocrine) functions.

In this article, we shall look at the anatomy of the pancreas – its structure, anatomical position and neurovascular supply.

AnatomicalPosition

The pancreas is an oblong-shaped organ positioned at the level of the transpyloric plane (L1). With the exception of the tail of the pancreas, it is a retroperitoneal organ, located deep within the upper abdomen in the epigastrium and left hypochondrium regions.

Within the abdomen, the pancreas has direct anatomical relations to several structures

Organs:

• Stomach – Separated from the pancreas by the lesser sac, the stomach and pyloruslie anterior and to the pancreas.
• Duodenum – The “C” shaped duodenum curves around and outlines the head of the pancreas. The first part of the duodenum lies anteriorly whereas the second part of the duodenum including the ampulla of Vater lies laterally to the right of the pancreatic head
• Transverse mesocolon – Attaches to the anterior surface of the pancreas
• Common bile duct – Descends behind the head of the pancreas before opening into the second part of the duodenum alongside the major pancreatic duct through the major duodenal papilla
• Spleen –located posteriorly and laterally. The lienorenal ligament is formed from peritoneum and connects the spleen to the tail of the pancreas.

Vessels

The pancreas lies near several major vessels and significant landmarks in vascular anatomy:

• The aorta and inferior vena cava pass posteriorly to the head of the pancreas.
• The superior mesenteric artery lies behind the neck of the pancreas and anterior to the uncinate process.
• Posterior to the neck of the pancreas, the splenic and superior mesenteric veins unite to form the hepatic portal vein.
• As it journeys from its origin at the celiac plexus to the splenic hilum, the splenic artery traverses the superior border of the pancreas.

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The Pancreas and Its Functions

Anatomical Structure

The pancreas is typically divided into five parts:

• Head – the widest part of the pancreas. It lies within the C-shaped curve created by the duodenum and is connected to it by connective tissue.
• Uncinate process – a projection arising from the lower part of the head and extending medially to lie beneath the body of the pancreas. It lies posterior to the superior mesenteric vessels.
• Neck – located between the head and the body of the pancreas. It overlies the superior mesenteric vessels which form a groove in its posterior aspect.
• Body –centrally located, crossing the midline of the human body to liebehind the stomach and to the left of the superior mesenteric vessels.
• Tail –the left end of the pancreas that lies within close proximity to the hilum of the spleen. It is contained within thesplenorenal ligamentwith the splenic vessels. This is the only part of the pancreas that isintraperitoneal.

Duct System

The exocrine pancreas is classified as alobulated, serous gland which produces digestive enzyme precursors. Itiscomposed of approximately one million ‘berry-like’ clusters of cells calledacini, connectedby shortintercalated ducts.

The intercalated ducts unite with those draining adjacent lobules and drain into a network of intralobular collecting ducts, which in turndrain into the mainpancreatic duct.

The pancreatic ductruns the length of the pancreas and unites with thecommon bile duct, forming thehepatopancreatic ampulla of Vater. This structure then opens into the duodenum via the major duodenal papilla.

Secretions into the duodenum are controlled by a muscular valve – thesphincter of Oddi.Itsurrounds the ampulla of Vater, acting as a valve.

Vasculature

The pancreas is supplied by thepancreatic branchesof thesplenic artery. The head is additionally supplied by thesuperiorandinferior pancreaticoduodenal arterieswhich are branches of thegastroduodenal(fromcoeliac trunk) andsuperior mesenteric arteries, respectively.

Venous drainage of the head of the pancreas is into thesuperior mesenteric branchesof thehepatic portal vein. The pancreatic veins draining the rest of the pancreas do so via thesplenic vein.

Lymphatics

The pancreas is drained by lymphatic vessels that follow the arterial supply. They empty into thepancreaticosplenal nodesand the pyloric nodes, which in turn drain into the superior mesenteric and coeliac lymph nodes.