Journal of Biomedical Sciences

Editorial Note

Gall bladder is reservoir of bile which is in the shape of piriform sac partly contains a fosa on the inferior surface of the right hepatic lobe. It extends from the right extremity of the porta hepatis to inferior border of the liver. The size of gall bladder is around 7 to 10 cm long and 3 to 4 cm broad at its widest part and can hold from 30 to 50 ml bile. The gall bladder is divided into fundus, body, infundibulum and neck. The fundus extends about 1 cm beyond the free edge of the liver. The body is the largest segment. The infundibulum is the transitional area between the body and the neck. Hartmanns pouch is a bulge on the inferior surface of the infundibulum.

Gallstones may become impacted here and can cause the obstruction of the cystic duct. The neck is the tapered segment of the infundibulum that is narrow and joins the cystic duct. The cystic duct is of 3 to 4 cm long and passes posteriorly inferior and to the left from the neck of the gallbladder to join the common hepatic duct to form the common bile duct. The mucosa of the cystic duct is arranged with spiral folds known as the valves of heister. A number of anomalies occur in the gall bladder. Further more the cystic duct inserts into the bile duct at a variety of sites. The arterial supply to the gall bladder is from the cystic artery. Because the cystic artery is an end artery, the gall bladder is more susceptible to ischaemic injury and necrosis as a result of inflammation or interruption of the artery. The cystic artery can originate from the right hepatic, left hepatic or the common hepatic artery and it can be anterior or posterior to the common hepatic duct. The venous drainage is only through the cystic vein which drains into the portal vein.

There are also some small veins that drains directly into the liver to the hepatic veins. The lymphatic drainage of the gall bladder proceeds mainly by the four routes, which form two pathways that drain in the thoracic duct. The diameter of the common bile duct is often used as an indication of biliary pathology. Its normal size varies depending on the modality used to measure it and a range of 4 to 13 mm has been reported. The most common modality to examine the common bile duct diameters is ultrasound and a diameter upto 6 mm is considered normal. Some consider the equivalent in contrast radiology to be 10 mm and this depends on the magnification.

There are more than 2 km of bile ductules and ducts in the adult human liver. These structures are far from being inert channels and are capable of significantly modifying biliaryflow and composition in response to hormonal secretion. Bile secretion starts at the level of the bile cannaliculus, the smallest branch of biliary tree. They form a meshwork between hepatocytes with many anastomatic interconnections.