Pancreas

The pancreas is a retroperitoneal organ that has both endocrine and exocrine functions: it is involved in the production of hormones (insulin, glucagon and somatostatin), and also involved in digestion by its production and secretion of pancreatic juice.

Gross anatomy

The pancreas can be divided into four main parts:

• head: thickest part; lies to the right of the superior mesenteric vessels (superior mesenteric artery (SMA), superior mesenteric vein (SMV))
  • uncinate process: extension of the head, posterior to SMV
  • attached to "C" loop of duodenum (D2 and D3)
• neck: thinnest part; lies anterior to SMA, SMV
  • SMV joins splenic vein behind pancreatic neck to form portal vein
• body: main part; lies to left of SMA, SMV
  • anterior surface is covered with peritoneum forming the posterior surface of the omental bursa (lesser sac)
  • splenic vein lies in groove on posterior surface of body
• tail: lies between layers of the splenorenal ligament in the splenic hilum

Pancreatic juice is secreted into a branching system of pancreatic ducts that extend throughout the gland. In the majority of individuals, the main pancreatic duct empties into the second part of duodenum at the ampulla of Vater. 

See article: pancreatic ducts for more information. 

Blood supply

Arterial supply to the head is primarily from  the inferior and superior pancreaticoduodenal arteries.  Branches of the splenic artery supply the body and tail via multiple branches including the dorsal pancreatic artery and greatgreater pancreatic artery (arteria pancreatica magna). 

The pancreatic and pancreaticoduodenal veins drain blood from the pancreas draining to the splenic vein, and the splenic and portal veins respectively. 

Variant anatomy

Annular pancreas 

An annular pancreas is an uncommon (~1 in 20,000 ¹) variation with partial or complete surrounding of the duodenum with pancreatic tissue. The ventral pancreatic anlage is responsible for this anomaly by dividing early into two segments:

• often detected incidentally in asymptomatic patients
• may be associated with duodenal stenosis, postbulbar ulcerations, pancreatitis or biliary obstruction

Bifid pancreas

Rare branching anomaly of the pancreas tail and its duct system, also known as fishtail pancreas ⁶.

Ectopic pancreatic tissue

Ectopic pancreatic tissue refers to pancreatic rests that lie outside and separate to the pancreatic gland. It is reportedly quite common, affecting ~5% (range 1-10%) ¹ of people, most of whom are completely asymptomatic.

Recognised locations for ectopic pancreatic tissue include the gastric antrum, proximal duodenum, ileum and Meckel diverticula.

Pancreatic clefts

Linear clefts may be seen which contain fat where small vessels enter the pancreas and are a common mimic of pancreatic laceration. They are most prominent at the junction of the body and neck ².

Related pathology

• traumatic pancreatic injury
• pancreatitis
• pancreatic neoplasms
• pancreatic calcifications