The pancreas is a soft, greyish-pink, lobulated gland. It is approximately 12-15cm long and is located deeply on the posterior abdominal wall. It runs transversely across the posterior abdominal wall behind the stomach from the duodenum to the spleen. It lies approximately on the transpyloric plane (L1 vertebral level) and slopes upwards from right to left.
Diagram illustrating location of pancreas - click to enlarge
The gland is divided into four parts from right to left; the head, the neck, the body and the tail. The head is the broadest part and is surrounded by the loop of the duodenum. The ucinate process projects to the left from its lowest portion.
The neck is about 2cm long and projects forwards, upwards and to the left of the head and merges with the body. The body is of fairly uniform width and is prism-like in section. It extends to the left towards the spleen where it is continuous with the tail. The tail is contained within the splenorenal ligament but all the other parts of the pancreas are retroperitoneal.
Diagram of pancreas anatomy - click to enlarge
The blood supply of the pancreas is derived from branches of the gastroduodenal artery known as the superior pancreaticoduodenal artery and from branches of the inferior mesenteric artery known as the inferior pancreaticoduodenal artery. The splenic artery supplies the remainder of the gland. The venous drainage of the pancreas is into the portal system.
Diagram to illustrate pancreatic blood supply - click to enlarge
The main pancreatic duct traverses the gland from left to right. Lobular ducts join at right angles with the main duct. It enlarges as it reaches the neck of the gland and it then turns down, backwards and to the right towards the bile duct. The ducts join the duodenum at the ampulla. Frequently an accessory pancreatic duct drains the lower part of the head.