GI Radiology > Biliary > Anatomy


Biliary System

  • The gallbladder functions as a resevoir for bile produced by the liver. It is 7-10cm long, 3cm wide at its broadest measure, and has a capacity of 30-50ml.
  • The gallbladder is divided into three regions as shown in the image on the right: fundus, body, and neck.
    • The fundus usually extends anteriorly, inferiorly, and to the right, extending beyond the inferior border of the liver to contact the anterior abdominal wall behind the ninth right costal cartilage.
  • Bile produced by the left and right portions of the liver travel through the right and left hepatic ducts (1-2mm in diameter). These two ducts join to form the common hepatic duct.
  • The common hepatic duct lies anterior to the portal vein and to the right of the hepatic artery.
  • The common hepatic duct descends roughly 3cm before the cystic duct (3-4cm long) from the gallbladder joins it from the right.
  • The cystic duct may have from five to twelve crescentic folds, similar to those found in the gallbladder.
  • These folds give the cystic duct the appearance of a spiral valve, which allow the duct to dilate when distended.
  • The union of the common hepatic duct and cystic duct forms the common bile duct.

  • Keep in mind that there are many variations of this main scheme.
  • The common bile duct is usually 7-8cm long and up to 6mm in diameter. Ductal diameter increases 0.5-1mm per decade.
  • The common bile duct passes posterior to the first portion of the duodenum. It then descends via a groove on the superolateral portion of the posterior head of the pancreas, sometimes traveling through the pancreas head. The four portions of the duodenum are labeled in white.
  • At the head of the pancreas, the common bile duct meets the pancreatic duct, and they exit into the second part of the duodenum, forming the hepatopancreatic ampulla (or ampulla of Vater).
  • A normal ultrasound and CT are given below for your reference.



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