Gallbladder

At a glance

English

Gallbladder

Latin (TA2)

Vesica biliaris

System

Digestive

Region

Abdomen

Side

Single, on the midline

About the gallbladder

The gallbladder lies in a shallow hollow, the gallbladder fossa, on the visceral surface of the liver, at the boundary between the right lobe and the quadrate lobe. It is about 7 to 10 cm long and holds around 30 to 50 ml of bile. Its rounded lower end peeps out beyond the sharp inferior border of the liver, while the rest narrows upwards and backwards towards the porta hepatis. It is described as a fundus, body and neck, with the neck continuing into the cystic duct.

The front and upper surface of the body is attached directly to the liver by loose connective tissue, and peritoneum passes over its free underside. Below and behind, it rests on the first part of the duodenum and the transverse colon, so a gallstone can occasionally erode through into either. The cystic duct runs from the neck to join the common hepatic duct and form the bile duct. Its lining is thrown into a spiral fold that helps keep the duct open.

Bile made continuously by the liver flows back up into the gallbladder when the sphincter at the end of the bile duct is closed. The lining, a single layer of tall columnar cells folded into a honeycomb of ridges, absorbs water and salts, concentrating the bile several-fold. When fatty food enters the duodenum, the hormone cholecystokinin makes the smooth muscle of the wall contract and the sphincter relax, squeezing the stored bile into the bowel to help emulsify fat.

Gallstones form when bile becomes oversaturated with cholesterol or pigment. Most cause no symptoms, but a stone stuck in the neck or cystic duct causes biliary colic, a severe pain under the right ribs often spreading to the right shoulder blade. Persistent blockage leads to inflammation of the gallbladder (cholecystitis), which gives tenderness when the fundus is pressed on deep breathing (Murphy's sign). A stone passing into the bile duct may cause jaundice or pancreatitis. Removal of the gallbladder, usually by keyhole surgery, is one of the commonest abdominal operations.

Function and supply

Function

Stores and concentrates bile, then releases it into the duodenum when fat arrives in the gut.

Nerve supply

Vagal fibres and sympathetic fibres from the coeliac plexus via the hepatic plexus; the right phrenic nerve supplies the overlying peritoneum, explaining shoulder-tip pain.

Blood supply

The cystic artery, usually from the right hepatic artery; cystic veins drain into the liver directly or into the portal vein.