The pancreatic duct.
The pancreatic duct, or duct of Wirsung (also, the major pancreatic duct due to the existence of an accessory pancreatic duct), is a duct joining the pancreas to the common bile duct to supply pancreatic juices which aid in digestion provided by the exocrine pancreas. The pancreatic duct joins the common bile duct just prior to the ampulla of Vater, after which both ducts perforate the medial side of the second portion of the duodenum at the major duodenal papilla. There are many anatomical variants reported but these are quite rare.
Accessory pancreatic duct
Most people have just one pancreatic duct. However, some have an additional accessory pancreatic duct, called the Duct of Santorini. Accessory pancreatic duct can be functional or non-functional and may open separately into the second part of the duodenum 
Compression, obstruction or inflammation of the pancreatic duct may lead to acute pancreatitis. The most common cause for obstruction is choledocholithiasis, or gallstones in the common bile duct. Obstruction can also be due to duodenal inflammation in Crohn's disease. A gallstone may get lodged in the constricted distal end of the ampulla of Vater, where it blocks the flow of both bile and pancreatic juice into the duodenum. Bile backing up into the pancreatic duct may initiate pancreatitis.
- Goel, Shivi; Rustagi, SM; Saha, S; Mehta, V; Suri, RK; Rath, G (July 2015). "Aberrant pancreatic ductal organisation: a case report.". Surgical and radiologic anatomy: SRA 37 (5): 543–6. doi:10.1007/s00276-015-1474-z. PMID 25840941.
- doctor/2941 at Who Named It?
- Moore KL, Dalley AF. 2006. Clinically Oriented Anatomy. 5th Ed. Lippincott Williams & Wilkins. p 287.
- 1. Mchonde GJ, Gesase AP. Termination pattern of main and accessory pancreatic ducts among Tanzanians. Anatomy Journal of Africa. 2014; 3(1):223-227.
- Moore, Keith L.; Dalley, Arthur F. (2006). Clinically Oriented Anatomy, Fifth Edition. Lippincott Williams & Wilkins. p. 287. ISBN 0-7817-3639-0.