Chapter 67: Gallbladder & Biliary Tree Anatomy

The gallbladder is a pear-shaped organ responsible for bile storage and concentration, typically holding around 25 ml but capable of expansion up to 50 ml. Anatomically, it is divided into the fundus, body, infundibulum, and neck, with important variants including the Phrygian cap fold and an occasional Hartmann’s pouch near the neck, which is often associated with gallstones. The fundus commonly projects past the inferior liver border and is a key location for clinical examination. The intrahepatic ducts are formed by bile ductules merging into segmental ducts; the right hepatic duct is notably formed by anterior and posterior sectoral ducts, exhibiting the critical anatomical curve known as Hjortsjö’s crook. Significant variability exists in intrahepatic duct drainage, with common variants including the trifurcation pattern (Type 2) and drainage of a sectoral duct into the left hepatic duct (Type 3). The extrahepatic segment includes the cystic duct (2–4 cm long), which drains the gallbladder into the common hepatic duct to form the bile duct. The bile duct itself is typically 6 to 8 cm long and is clinically divided into supraduodenal, retroduodenal, and pancreatic segments. Distally, the bile duct often joins the pancreatic duct to form the hepatopancreatic ampulla (of Vater), which opens onto the major duodenal papilla. The flow of bile and pancreatic secretions is regulated by the sphincter of Oddi, a complex arrangement of smooth muscle inhibited by cholecystokinin (CCK), which also triggers gallbladder contraction. The anatomy of the cystic artery, typically arising from the right hepatic artery and located within the cystohepatic triangle (or hepatobiliary triangle), is crucial for surgeons, as numerous arterial and ductal variations—such as subvesical ducts or anomalous cystic duct junctions—are common and carry a high risk of iatrogenic injury during procedures like cholecystectomy. Clinically, understanding the path of gallstones, which can cause obstruction leading to biliary colic, acute cholecystitis, or the common hepatic duct compression known as Mirizzi syndrome, relies heavily on this detailed anatomical basis.