The pancreas is a retroperitoneal and an accessory organ of the gastrointestinal tract whose function is to release various substances that help regulate the blood content levels as well as digestion. It is found lying transversely in the epigastric region of the abdomen, behind the stomach.
It consists of two different types of glands, known as the exocrine glands which produce digestive enzymes and the endocrine glands which produce hormones. In this article, the parts of the pancreas, the pancreatic ducts, the vascular, lymphatic and nervous supply will be discussed, with a brief overview of a pathological disorder known as pancreatitis to finish.
Parts of the Pancreas
There are four theoretical parts of the pancreas which will now be review from left to right:
The tail of the pancreas is the most lateral of the four parts and its surrounding structures include:
- the left kidney posteriorly
- the hilum of the spleen laterally
- the left colic flexure inferiorly
- the stomach anteriorly
The body of the pancreas is the largest of the four parts and it lies at the level of the second lumbar vertebra. Posteriorly it is bordered by:
- the abdominal aorta
- the superior mesenteric artery
- the left kidney
- the left suprarenal gland and their related vessels
Inferiorly it lies upon the omental bursa and anteriorly it faces the posterior aspect of the stomach.
The neck of the pancreas is situated superiorly to the superior mesenteric vessels and posterior to the pylorus of the stomach. Posteriorly the superior mesenteric vein and the splenic vein merge to form the portal vein.
Lastly, the head of the pancreas which is the most medial of the four parts. is encircled by the C-shape made from the initial section of the duodenum and is superior to:
- the inferior vena cava
- the renal veins
- the right renal artery
It is in this part of the pancreas that the bile duct is embedded. Inferiorly, the uncinate process extends to the left.
The Pancreatic Ducts
There are two pancreatic ducts, namely the main pancreatic duct and its accessory. Both of these ducts drain into the second portion of the duodenum. The main duct opens into the major duodenal papilla by merging with the common bile duct and forming the hepatopancreatic ampulla. The opening is surrounded by the sphincter of Oddi smooth muscle.
The accessory duct, which is usually present, drains into the secondary duodenal papilla, providing that it is present and that it is patent. Should the papilla be absent, the accessory duct simply joins up with the main duct.
The lymphatic drainage of the pancreas collects in the pancreaticosplenic nodes after travelling along the splenic artery.
The arterial blood supply comes mostly from the splenic artery and its consequent branches. Also, the gastroduodenal artery, the superior mesenteric and the superior and inferior pancreaticoduodenal arteries make a contribution.
The splenic vein, the portal vein and the superior mesenteric vein share the venous drainage of the area.
The nervous supply comes from the vagus nerve (CN X) and the thoracic splanchnic nerves. The celiac plexus and the superior mesenteric plexus also contribute fibers.
Pancreatitis is an inflammatory disorder of the pancreatic tissues. This is a serious disease because it can cause extensive damage to the exocrine pancreatic parenchyma and in the most severe of cases the patient will die. There are acute and chronic forms, with the possibility of an acute patient going into remission.
Etiologic factors include:
- metabolic disturbances
- genetic mutations
- mechanical trauma
The best course of treatment is to eliminate the underlying cause and limit the extent of the inflammation as quickly as possible.