The ductal embryology of the pancreas is moderately complicated, leading to a number of anatomical variants of the pancreatic ducts, many of which are clinically significant.
The pancreatic duct extends from the tail to the head, and joins with the common bile duct at a 60 degree angle at the hepatopancreatic ampulla.
Conventional pancreatic ductal anatomy is described below.
Main pancreatic duct
- portion of the dorsal duct proximal to the dorsal-ventral fusion point
- drains at the ampulla of Vater
- connects with the accessory pancreatic duct (of Santorini) (see below) if present
Nomenclature of the main pancreatic duct can be confusing :
- based on distance from pancreatic head: proximal (head region); distal (tail region)
- based on direction of secretion flow: proximal (tail region); distal (head region)
- it may be best to refer to duct location by region, e.g. "duct in the head region" to avoid confusion
Pancreatic duct of Wirsung
- distal portion of the main pancreatic duct
- segment of the ventral duct between the dorsal-ventral fusion point and the major papilla
- continuous with the main pancreatic duct proximally
Accessory pancreatic duct (of Santorini or Bernard)
- portion of the dorsal duct distal to the dorsal-ventral fusion point
- drains anterior and superior portion of the head
- in 70% of individuals drains to the minor papilla
- in 30% of individuals persists as a branch of the main pancreatic duct
Variants of the pancreas which result in ductal variations are covered in the pancreas article.
A pancreas divisum is the most common variation of pancreatic duct formation and can account for up to 14% . It results from the failure of fusion of dorsal and ventral pancreatic anlages. As a result, the dorsal pancreatic duct drains most of the pancreatic glandular parenchyma via the minor papilla. Although controversial, this variant is considered as a cause of pancreatitis .
Pancreatic divisum can result in a santorinicele , which is a cystic dilatation of the distal dorsal duct, immediately proximal to the minor papilla .
Three subtypes are known :
- type 1: classic, no connection at all; occurs in the majority of cases (~70%)
- type 2: absent ventral duct, minor papilla drain all of pancreas while major papilla drains bile duct (~25%)
- type 3: functional, filamentous or inadequate connection between dorsal and ventral ducts (~5%)
Meandering main pancreatic duct
Meandering main pancreatic duct (MMPD) comprises of a reverse Z-type and loop-type of pancreatic ducts.
Ansa pancreatica is a rare anatomic variation of the pancreatic ducts. It is a communication between the main pancreatic duct and the accessory pancreatic duct.
Anomalous pancreaticobiliary junction
Anomalous pancreaticobiliary junction refers to the union of the pancreatic duct and common bile duct outside the duodenal wall.
History and etymology
The duct of Wirsung was first reported in an etching by Johann Georg Wirsung (1589-1643), a German-Italian anatomist .
The accessory pancreatic duct of Santorini is named after Giovanni Domenico Santorini (1681-1737), an Italian professor of medicine .