Gallbladder and biliary tree

The gallbladder lies in a fossa on the visceral surface of the liver between segments IV and V, with its fundus often projecting just beyond the inferior liver margin near the right costal margin. The common bile duct runs in the free edge of the lesser omentum, behind the first part of the duodenum and through or behind the head of the pancreas.

The gallbladder has a fundus, body, infundibulum (Hartmann pouch) and neck continuing as the cystic duct, which has a spiral fold. The right and left hepatic ducts join to form the common hepatic duct, which is joined by the cystic duct to form the common bile duct. This usually unites with the main pancreatic duct at the hepatopancreatic ampulla (ampulla of Vater), opening at the major duodenal papilla and controlled by the sphincter of Oddi. Calot triangle is bounded by the cystic duct, common hepatic duct and the inferior surface of the liver and contains the cystic artery.

The cystic artery, usually from the right hepatic artery, supplies the gallbladder, commonly running in Calot triangle, and variants are frequent. The cystic vein drains to the portal vein or directly to the liver, and the common bile duct is supplied by the cystic, right hepatic and gastroduodenal or pancreaticoduodenal branches.

Sympathetic and parasympathetic fibres reach the biliary tree through the coeliac plexus and the vagus nerve. Cholecystokinin (a hormone) stimulates gallbladder contraction and sphincter of Oddi relaxation, while visceral pain is felt in the epigastrium and right hypochondrium, and irritation of adjacent diaphragm refers pain to the right shoulder via the phrenic nerve.

The liver secretes up to about 1 litre of bile daily. The gallbladder concentrates and stores bile, and contracts after a fatty meal under cholecystokinin to release it into the duodenum, where bile salts emulsify fats and aid absorption of fat-soluble vitamins.

Gallstones may cause biliary colic, acute cholecystitis (with a positive Murphy sign), choledocholithiasis, cholangitis and gallstone pancreatitis. Obstructive jaundice results from duct obstruction by stones or tumours, such as carcinoma of the head of the pancreas. In laparoscopic cholecystectomy, identification of the structures in Calot triangle is essential because of anatomical variation and the risk of bile duct injury.

• Gallbladder parts: fundus, body, infundibulum (Hartmann pouch), neck; cystic duct with spiral fold.
• Common hepatic duct + cystic duct = common bile duct.
• Common bile duct joins the main pancreatic duct at the ampulla of Vater, opening at the major duodenal papilla; sphincter of Oddi controls flow.
• Calot triangle: cystic duct, common hepatic duct, inferior liver edge; contains the cystic artery (usually from the right hepatic artery).
• Cholecystokinin causes gallbladder contraction and relaxation of the sphincter of Oddi; Murphy sign in acute cholecystitis.

1. Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. Elsevier — Tier 3 (textbook)
2. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. Wolters Kluwer, 8th edition (2018) — Tier 3 (textbook)
3. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. Elsevier, 11th edition (2020) — Tier 3 (textbook)

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