Now that we've looked at the pancreas, we'll return to the liver and see the parts of the biliary sytem that lie outside it: the hepatic ducts, the cystic duct and gallbladder, and the common bile duct. We'll look from behind at a liver in which these structures have been dissected out.
Here at the porta hepatis our view of the structures of the biliary system is crowded by the portal vein, and the hepatic artery. We'll remove those blood vessels, to simplify the the picture. Here are the right and left hepatic ducts, the main branches of a tree that extends throughout the liver. They unite here to form the common hepatic duct.
The common hepatic duct goes to here, where it's joined by the narrow cystic duct. The cystic duct, which runs in a spiral, fills and empties the gall bladder. Below this junction, the main passage for bile gets a different name: from here down to the duodenum it's the common bile duct. We'll follow it in a minute.
The gall bladder is a reservoir for bile. It fills and empties by way of the cystic duct, filling passively, and emptying by contraction of its muscular wall. The lower part of the gallbladder hangs down below the free border of the liver. Its upper part is held against the underside of the liver by a common sheet of peritoneum, most of which has been removed here.
To follow the common bile duct, we'll go to an intact dissection, seen from in front. We've removed the left lobe of the liver, and the transverse colon. Here's the gall bladder. Here's the lesser curve of the stomach.
Here, between the liver and the first part of the duodenum, is the thickened lower part of the lesser omentum, also called the hepatoduodenal ligament. It's quite darkly stained with bile in this specimen.
The common bile duct lies within it, quite close to the epiploic foramen, which is here. To see the common bile duct, we'll dissect into this part of the hepatoduodenal ligament.
Here's the common bile duct. It passes down, out of sight, behind the first part of the duodenum. To follow it we'll mobilize the duodenum and pull it over to the left. Here's the distal part of the common bile duct, dissected free from its surroundings. As it nears the duodenum it's almost embedded in the back of the head of the pancreas.
Here's a duodenum cut open so we can see where the common bile duct and pancreatic ducts end. On the outside here's the common bile duct, here's the main pancreatic duct. Here's a minor pancreatic duct.
On the inside, the bile duct passes downward beneath the duodenal mucosa, creating this bulge. The bile duct and the main pancreatic duct open here, at the duodenal papilla.