No. 7 1. Liver 2. Gallbladder and Biliary Ducts 3. Pancreas

Section 7 The Liver The liver (Hepar) is the largest gland in the body. It lies mainly in the upper and right parts of the abdominal cavity below the right half of the diaphragm and extends to the left of the midline for about 3 cm. In the male it commonly weights 1.2-1//5 kg, in the female 1.0-1.3kg. The liver is divided morphologically into a large right lobe and a smaller left lobe by the falciform ligament. According to the internal structure of the lover, it can also be divided into two halves and then subdivided into some segments in each half.

The liver presents two surfaces: The superior or diaphragmatic surface and inferior or visceral surface. The diaphragmatic surface is smooth and shaped so that it fits the diaphragm. A posterior part of this surface is devoid of peritoneal covering and is attached to the diaphragm by areolar tissue, called the bare area of liver. The right and left lobes are separated by a fold of parietal peritoneum called the falciform ligament, which attaches the liver to the anterior abdominal wall.

In the free margin of the falciform ligament is a fibrous cord called the ligamentum teres hepatis (round ligament). The ligamentum teres is the remnant of the fetal umbilical vein that transported blood from the placenta to the liver. The falciform ligament is continuous on the superior surface of the liver with the coronary ligament, a fold of the parietal peritoneum that attaches the liver to the undersurface of the diaphragm. The coronary ligament consists of anterior and posterior layers that are joined at their lateral margins by right and left triangular ligaments. Between the two layers of the coronary ligament is a region called the bare area of the liver. The bare area, which rests against the diaphragm, is the only portion of the liver that is not covered with visceral peritoneum.

This surface is marked off by a H-shaped fissures and grooves. The inferior or visceral surface: The inferior or visceral surface is slightly concave and is directed inferiorly and posteriorly. This surface is marked off by a H-shaped fissures and grooves. The cross-bar of the “H” is the porta hepatis, which may be regarded as the hilum of the liver. Through the porta hepatis the hepatic portal vein, the proper hepatic artery and the hepatic nerve plexus enter the liver, and the right and left hepatic ducts and some lymph vessels emerge. These structures are contained beneath the liver in the right free border of the lesser omentum. The inferior surface presents four lobes, i.e. left, right, quadrate and caudate lobes.

Section 8 The Gallbladder and Biliary Ducts Constitution of biliary ducts: gallbladder and cystic duct, right and left hepatic ducts, common hepatic duct, common bile duct.

Bile is produced by hepatocytes and collected in the tyny canaliculi bordered by the hepatocytes themselves. These bile canaliculi unite to form the right and left hepatic ducts. Two hepatic ducts join together to form the common hepatic duct. The latter is joined by the cystic duct, the duct of gallbladder, to form the common bile duct. The common bile duct is joined by the main pancreatic duct before the two open together into the duodenum.

Ⅰ. The Gallbladder The gallbladder, a small sac on the inferior surface of the liver, is 7～10 cm long, 3 cm broad at its widest part, and 30～50 ml in capacity. Functions: It serves as a storage site for bile, which it receives from the liver. It also concentrates the bile by reabsorbing water from it. Morphology: The gallbladder consists of the fundus, body, neck and cystic duct.

①The fundus is the expanded blind anterior end of the organ projecting beyond the inferior margin of the liver. The point of gallbladder: The gallbladder lies behind the point where the lateral edge of the right rectus abdominis crosses the costal arch. ②The body tapers toward the neck, which lies in contact with the visceral surface of the liver.

③The neck is attached to the liver by areolar tissue in which the cystic artery is embedded. The mucous membrane lines the luminal aspect of the neck and forms oblique ridges, the spiral folds. ④The cystic duct is up to 5 cm ling and runs backward and downward from the neck of the gallbladder. Bile enters and leaves the gallbla;dder through the cystic duct. The cystic duct joins with the common hepatic duct from the liver to form the common bile duct.

Ⅱ. The Common Bile Duct It is formed near the porta hepatis by the junction of the cystic and common hepatic ducts. The common bile duct is usually about 7.5 cm long and about 6 mm in diameter. It lies in the right border of the lesser omentum, in front of the right edge of the hepatic portal vein, and on the right of the proper hepatic artery.

It runs behind the superior part of the duodenum and passes in a groove on the posterior surface of the head of the pancreas. At the left side of the descending part of the duodenum the common bile duct comes into contact with the main pancreatic duct and accompanies it into the wall of this part of the gut, where the two ducts usually units to from the hepatopancreatic ampulla. The distal constricted end of this ampulla opens into the descending part of the duodenum on the summit of the major duodenal papilla.

The circular muscle around the lower part of the common bile duct, including the ampulla and the terminal part of the main pancreatic duct, is thickened and is called the sphincter of common bile duct, sphincter of hepatopancreatic ampulla (Oddi’s sphincter) and sphincter of pancreatic duct respectively. When the sphincter relaxes and the smooth muscle in the wall of the gallbladder contracts, bile is propelled into the intestine. When the sphincter contracts, bile from the liver fills the common bile duct and then enters the gallbladder via the cystic duct.

Section 9 The Pancreas The pancreas is a long, soft, finely lobulated gland. It located in the upper part of the abdomen, hidden by many organs. The pancreas can be divided into head, neck, body and tail. The head lies in the C-curve of the duodenum. Toward the left, the upper part of the head is continuous with the neck, the lower part of the head projects the uncinate process which hooks posteriorly to the superior mesenteric vessels. The common bile duct lies either in a groove on the upper and posterior surface of the head of the pancreas or is embedded in it.

The neck is about 2 cm long The neck is about 2 cm long. Its posterior surface is in relation with the superior mesenteric vein and the beginning of the hepatic portal vein. The body lies above the duodenojejunal flexure and on the left kidney. It is separated from the stomach by the omental bursa. The tail of the pancreas is narrow, and usually lies in contact with the inferior part of the visceral surface of the spleen.

The pancreatic ducts: The exocrine secretions of the pancreas are collected by two ducts, the main and accessory pancreatic ducts; both drain into the second part of duodenum.