The pancreas is an organ of the digestive system and endocrine system of vertebrates. In humans, it is located in the abdomen behind the stomach and functions as a gland. The pancreas has both an endocrine and a digestive exocrine function. As an endocrine gland, it functions mostly to regulate blood sugar levels, secreting the hormones insulin, glucagon, somatostatin, and pancreatic polypeptide. As a part of the digestive system, it functions as an exocrine gland secreting pancreatic juice into the duodenum through the pancreatic duct. This juice contains bicarbonate, which neutralizes acid entering the duodenum from the stomach; and digestive enzymes, which break down carbohydrates, proteins, and fats in food entering the duodenum from the stomach.

Inflammation of the pancreas is known as pancreatitis, with common causes including chronic alcohol use and gallstones. Because of its role in the regulation of blood sugar, the pancreas is also a key organ in diabetes mellitus. Pancreatic cancer can arise following chronic pancreatitis or due to other reasons, and carries a very poor prognosis, as it is often identified when it has spread to other areas of the body.

The word pancreas comes from the Greek πᾶν (pân, “all”) & κρέας (kréas, “flesh”). The function of the pancreas in diabetes has been known since at least 1889, with its role in insulin production identified in 1921.

The pancreas is an organ that in humans lies in the abdomen, stretching from behind the stomach to the left upper abdomen near the spleen. In adults, it is about 12–15 centimetres (4.7–5.9 in) long, lobulated, and salmon-coloured in appearance.

Anatomically, the pancreas is divided into a head, neck, body, and tail. The pancreas stretches from the inner curvature of the duodenum, where the head surrounds two blood vessels: the superior mesenteric artery, and vein. The longest part of the pancreas, the body, stretches across behind the stomach, and the tail of the pancreas ends adjacent to the spleen.

Two ducts, the main pancreatic duct and a smaller accessory pancreatic duct, run through the body of the pancreas, joining with the common bile duct near a small ballooning called the ampulla of Vater. Surrounded by a muscle, the sphincter of Oddi, this opens into the descending part of the duodenum.

The head of the pancreas sits within the curvature of the duodenum, and wraps around the superior mesenteric artery and vein. To the right sits the descending part of the duodenum, and between these travel the superior and inferior pancreaticoduodenal arteries. Behind rests the inferior vena cava, and the common bile duct. In front sits the peritoneal membrane and the transverse colon. A small uncinate process emerges from below the head, situated behind the superior mesenteric vein and sometimes artery.

The neck of the pancreas separates the head of the pancreas, located in the curvature of the duodenum, from the body. The neck is about 2 cm (0.79 in) wide, and sits in front of where the portal vein is formed. The neck lies mostly behind the pylorus of the stomach, and is covered with peritoneum. The anterior superior pancreaticoduodenal artery travels in front of the neck of the pancreas.

The body is the largest part of the pancreas, and mostly lies behind the stomach, tapering along its length. The peritoneum sits on top of the body of the pancreas, and the transverse colon in front of the peritoneum. Behind the pancreas are several blood vessels, including the aorta, the splenic vein, and the left renal vein, as well as the beginning of the superior mesenteric artery. Below the body of the pancreas sits some of the small intestine, specifically the last part of the duodenum and the jejunum to which it connects, as well as the suspensory ligament of the duodenum which falls between these two. In front of the pancreas sits the transverse colon.

The pancreas narrows towards the tail, which sits near to the spleen. It is usually between 1.3–3.5 cm (0.51–1.38 in) long, and sits between the layers of the ligament between the spleen and the left kidney. The splenic artery and vein, which also passes behind the body of the pancreas, pass behind the tail of the pancreas.

Regards
Amalia Azzariti
Managing Editor
Journal of Clinical Oncology and Cancer Research