Extrahepatic bile duct includes

Outside the liver, the bile duct includes many organs, first of all the gallbladder and cystic duct. It is like a pipe in the human body, winding and connected in circles. Both the liver and gallbladder part and the intestinal part have many important functions. In normal times, we must protect the liver, because the liver can play a detoxification role and is of great value to the body.

1. Gallbladder and cystic duct

The gall bladder is a long eggplant-shaped sac-like organ, about 8-12 cm long, 3-5 cm wide, with a capacity of about 40 ml. It is located in the gallbladder fossa on the visceral surface of the liver. It is connected to the liver by loose connective tissue on the top and is covered with peritoneum on the other sides. The gallbladder stores and concentrates bile and regulates bile duct pressure.

The gallbladder can be divided into three parts: the fundus, body and neck. The base faces forward and protrudes slightly from the front edge of the liver. Its surface projection is equivalent to the intersection of the right clavicle midline and the right costal arch. The smooth muscle layer at the bottom is thin and less elastic, making it a common site for gallbladder perforation. Since the gallbladder moves up and down with the liver during breathing, sometimes even a small perforation is difficult to heal by adhesion.

The body contains a large amount of elastic fibers and has great elasticity. The neck is curved and thin, with a bulging upper part called Hartmann's pouch. The gallbladder is adjacent to the transverse colon and duodenum below, so in cholecystitis the neck of the gallbladder is often adhered to the upper part of the duodenum, adjacent to the pyloric part of the stomach on the left, and attached to the anterior abdominal wall in front.

The cystic duct is about 3-5 cm long and is located within the hepatoduodenal ligament. It is the continuation of the gallbladder neck to the lower left. At the end near the gallbladder neck, there are spiral folds in the mucosa, called Heister's valve, while the mucosa at the end close to the common bile duct is smooth.

The Heister valve prevents the cystic duct from excessive expansion or contraction, which facilitates the discharge of bile. However, when this valve becomes edematous or has stones impacted during bile duct inflammation, it may lead to gallbladder accumulation. The cystic duct usually intersects with the common hepatic duct at an acute angle to form the common bile duct.

The cystic artery usually arises from the right hepatic artery in the gallbladder triangle. The gallbladder vein usually joins the main trunk or right branch of the portal vein.

2. Hepatic duct, common hepatic duct, and common bile duct

The bile ducts of the left and right hepatic halves merge into one hepatic duct. The left hepatic duct is located higher up, runs horizontally in the transverse groove of the portal of the liver, is thin and relatively long (2.5-4.0 cm long), and merges into the common hepatic duct at a nearly right angle. Although bile duct stones are easy to touch, due to the small angle between the bile duct and the common bile duct, it is not easy for the stones to pass on their own, and it is also difficult to open the common bile duct to remove the stones. The right hepatic duct is deep, thick and short (only 2-3 cm), and its confluence angle with the common hepatic duct is about 150°, which is conducive to bile drainage and spontaneous stone excretion. Clinically, hepatic duct stones are more common on the left side.