Liver and Biliary Tree
Common Bile Duct
The CBD is 7-8 cm long and normally no more than 6 mm in diameter in adults. In elderly patients, the duct will dilate 1 mm per decade after 60, i.e. 7 mm at 70 years, 8 mm at 80 years and so on.
The CBD has three parts to its course. It tapers as it pierces and opens into the medial wall of the second part of the duodenum, about halfway down its length.
The CBD is usually joined by the main pancreatic duct, and together they open into a small ampulla in the duodenal wall, called the ampulla of Vater. The ampulla opens into the lumen of the duodenum by means of the major duodenal papilla.
Circular muscle fibres, known as the sphincter of Oddi, surround the terminal parts of both ducts and the ampulla.
The CBD and the main pancreatic duct share a common papilla in 60%, the remainder have separate orifices.
The arterial supply of the bile duct is important due to its potential vulnerability during surgery. Furthermore, it is quite complex with seven arteries described and multiple anastomoses between them. The most important of these arteries are: