Chapter 21: Biliary Tract
Regarding the extrahepatic biliary and vascular anatomy, which of the following is true?
(A) The cystic artery usually arises from the left hepatic artery.
(B) The common duct courses downward posterior to the portal vein in the free edge of the lesser omentum.
(C) The right branch of the hepatic artery crosses the main bile duct posteriorly.
(D) The cystic artery usually crosses the common hepatic duct posteriorly.
(C) The extrahepatic bile ducts are represented by the extrahepatic segments of the right and left hepatic ducts joining to form the biliary confluence and the main biliary channel training to the duodenum (Fig. 21-5). The accessory biliary apparatus comprises the gallbladder and the cystic duct. The confluence of the right and left hepatic ducts takes place at the right of the hilar fissure of the liver anterior to the portal venous bifurcation and overlying the origin of the right branch of the portal vein.
FIGURE 21-5. Biliary anatomy. Reprinted from Gunn A, Keddie N. Some clinical observations on patients with gallstones. Lancet. 1972;300(7771):239-241, Copyright 1972, with permission from Elsevier.
The main bile duct, the mean diameter of which is about 6 mm, is divided in two segments: the proximal segment (common hepatic duct) above the cystic duct and the CBD distal to the cystic duct. The latter courses downward anterior to the portal vein in the free edge of the lesser omentum and is closely applied to the hepatic artery, which runs upward on its left, giving rise to the right branch of the hepatic artery, which crosses the main bile duct posteriorly, although in about 20% of the cases anteriorly.
The cystic artery arises from the right hepatic artery in 95% of the population and may cross the common hepatic duct posteriorly or anteriorly (Fig. 21-6). The triangle of Calot is made up of the edge of liver, common hepatic duct, and cystic duct. Dissection of Calot’s triangle is of key significance during cholecystectomy because in this triangle runs the cystic artery, often the right branch of the hepatic artery, and occasionally a bile duct. There are a large number of ductal and arterial anatomical variances. The most common ductal variant is that 20% of people have a right anterior duct directly. The most common vascular variant is that 20% will have a replaced left hepatic artery coming off the left gastric artery and transverses through the hepatogastric ligament.
FIGURE 21-6. Variations in biliary anatomy (from Brunicardi FC, Andersen DK, Billiar TR, et al., eds. Schwartz’s Principles of Surgery. 10th ed. ...