Gallbladder and Extrahepatic Biliary System

Abstract

The biliary system forms a conduit whereby bile produced by hepatocytes is transmitted to and concentrated in the gallbladder and finally excreted into the duodenum. Bile is first secreted into bile canaliculi, which form the smallest branches of the biliary system. Canaliculi drain into interlobular bile ducts, which join to form progressively larger intrahepatic ducts until the left and right hepatic ducts emerge from the liver in the region of the porta hepatis. Slightly distal to the porta hepatis, the left and right hepatic ducts join to form the common hepatic duct. The common hepatic duct is then joined on its right side by the cystic duct of the gallbladder to form the common bile duct. The distal common bile duct usually joins with the pancreatic duct within the head of the pancreas and empties into the duodenum at the ampulla of Vater. The exact anatomy and lengths of the various extrahepatic ducts vary among individuals. The common hepatic duct ranges from 1 to 5 cm in length, the cystic duct from 2 to 6 cm, and the common bile duct from 5 to 10 cm. The usual diameter is 4 to 5 mm for the cystic duct and 5 to 7 mm for the common bile duct.