This article is only available in the PDF format. Download the PDF to view the article, as well as its associated figures and tables. THE COMMON bile duct is a conduit serving to transport bile from the liver to the duodenum. This pipeline includes a "surge chamber" (represented by the gall bladder) permitting both storage and availability. The duct also has a "nozzle" at its termination, which increases the flow of bile to jetstream velocity. These concepts conform to hydraulic principles. The common bile duct has a constantly curving course. Its termination at the papilla of Vater is like a funnel in that the diameter of the lumen decreases rapidly. The external appearance of the terminal (transduodenal) segment of the common bile duct is that of an expanded bulb. This enlargement occurs where the pancreatic duct appears to join the termination of the common bile duct. This bulbous character, for many years, led to a belief that a "space" was formed by the confluence of the pancreatic and common bile ducts. When the enlarged