All About the Pancreas

The pancreas is a very important organ of the body. It has both endocrine and exocrine functions. It's well known for its regulation of glucose, which is dysfunctional in the disease diabetes mellitus. This is an autoimmune disease destroying the insulin-producing cells of the pancreas. The pancreas has 4 parts, the head, neck, body and tail.

It's shaped like a walking stick and is located by vertebrae L1-L2 in both the supra colic and infra colic sections. It's found at an oblique angle going from right to left upwards at an angle. The head is surrounded by the duodenum, the superior, descending, and horizontal parts. The pancreas is located anterior of the inferior vena cava and posterior to the stomach. It's body passes over the left renal vein, aorta, left crus of the diaphragm, lower pole of the left adrenal gland, and hilum of the left kidney. The splenic artery can be found just above the superior border of the pancreas, while the splenic vein runs close to the posterior border where it joins the inferior mesenteric vein just on front of the renal vein.

The pancreas is finely lobulated and is of solid consistency. It is made up of 80% exocrine acini with scattered 'islets of Langerhans' making up the 2% endocrine portion. The other 18% is made up of ducts and vessels. The islets are mostly located at the tail of the pancreas. The pancreatic duct goes from the tail to the head and grows as more tribulations join it. It then joins the bile duct forming the hepatopancreatic ampulla which empties through the major papilla into the proximal duodenum at the junction of the foregut and midgut. The lower part of the head and uncinate process are drained by the accessory pancreatic duct which drains through the minor papilla, located 2cm superior to the major papilla. The hepatopancreatic ampulla is surrounded by sphincteric muscle, the ampullary sphincter of Oddi is the control mechanism of the flow in the ducts. It often has a portion located on the inferior portion that points up and to the left called the uncinate process.

Blood Supply
The blood supply of the pancreas mostly comes from branches of the splenic artery which supplement the neck, body and tail. The branches include the dorsal pancreatic artery, the inferior and greater pancreatic arteries. The head is supplied by the superior and inferior pancreaticoduodenal arteries which original from the coeliac and mesenteric artery, respectively. The veins that drain the pancreas drain into the splenic vein, superior and inferior pancreaticduodenal veins. The latter two which drain into the mesenteric veins.

Lymph Drainage
In the head of the pancreas, lymph drainage follows the pancreaticoduodenal arteries and eventually drain into the coeliac and mesenteric lymph nodes. The body drains into the pancreaticoplenic nodes, eventually ending up in the coeliac nodes.

Nerve Supply
Branches of the vagus reach the pancreas through the posterior vagal trunk and coeliac plexus, which stimulate exocrine function. Sympathetic vasoconstrictor fibers originate at T6-T10 and pass via the coeliac plexus.