The falciform ligament (with the ligamentum teres at its free margin) is the embryonic remnant of the ductus venosus (umbilical vein) of the umbilical cord. It is a peritoneal structure that courses between the anatomical left and right lobes of the liver and the anterior abdominal wall.

 

As the falciform ligament passes onto the superior surface of the liver, the two layers of peritoneum diverge to the right and to the left, creating the anterior layers of the coronary ligaments. 

These pass to the right and to the left to the extremes of the superior liver surface, turn back on themselves (creating the triangular ligaments), and turn posteriorly to form the posterior layers of the coronary ligaments. In this manner, an area devoid of visceral peritoneum is created, the bare area of the liver. 

The posterior layers of the coronary ligaments converge to form the lesser omentum, which passes from the visceral surface of the liver to the lesser curvature of the stomach (hepatogastric ligament) and the first part of the duodenum (hepatoduodenal ligament).

 

The liver is divided anatomically into four lobes by external landmarks and is delineated on the visceral surface by fissures and fossae, which form the letter H.

The right side of the H is formed by fossae for the gallbladder and the IVC, and the right lobe lies to the right of these structures. The left side of the H is formed by the fissure for the round ligament and the ligamentum venosum (adult remnant of the ductus venosus); the left lobe is to the left of this fissure. The crossbar of the H is the porta hepatis, through which the hepatic artery, portal vein, and nerves enter the liver and the bile ducts and lymphatics exit.

The crossbar subdivides the central portion into quadrate and caudate lobes. Functionally, the right portal lobe lies to the right of the fossae of the gallbladder, IVC, and a portion of the caudate lobe. The left portal lobe is the left anatomical lobe, quadrate lobe, and the remainder of the caudate lobe. The portal lobes are supplied by lobar branches of the hepatic artery, portal vein, and bile ducts. Although lacking external landmarks, the portal lobes are further divided functionally into hepatic segments.

The larger right lobe occupies the right hypochondrium has two additional smaller lobes at its posterior-inferior surface, the caudate and quadrate lobes.

See: 3D Interactive Liver Anatomy

The liver receives a dual blood supply.

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The liver receives a dual blood supply; approximately 30 percent of the blood entering the organ is from the hepatic artery, and 70 percent is from the portal vein. The proper hepatic artery is a branch of the common hepatic artery, one of the three major branches of the celiac artery. As it approaches the liver, it divides into right and left hepatic branches that enter the liver and divide into lobar, segmental, and smaller branches. Eventually, blood reaches the arterioles in the portal areas at the periphery of the hepatic lobules and, after providing oxygen and nutrients to the parenchyma, drains into the hepatic sinusoids. The majority of blood entering the liver is venous blood rich in nutrients and molecules absorbed by the gastrointestinal organs. Intrahepatic branches of the portal vein follow the arteries to the portal areas, where portal venules empty into the sinusoids from which molecules are extracted and added. Sinusoidal blood flows to the central vein of each lobule from which increasingly large veins are formed until typically three hepatic veins exit the liver to join the IVC.

The portal venous system arises from the capillary beds within the abdominal organs supplied by the celiac artery, superior mesenteric artery (SMA), and inferior mesenteric artery (IMA), and blood will flow to and through the liver for metabolism of its contained molecules. Veins from these organs for the most part accompany arteries of the same name. The portal vein itself is formed by the union of the splenic vein and SMV posterior to the neck of the pancreas. This short, wide vein ascends within the hepatoduodenal ligament, posterior to the bile duct and hepatic artery, and enters the liver through the porta hepatis. Typically, the IMV drains its blood into the splenic vein.

Portacaval (systemic) venous anastomoses occur at sites where blood may ultimately drain into the portal system and/or the vena caval system. If venous flow through the portal system is prevented by liver disease, for example, the absence of valves within the portal system veins allows reverse flow. This dilates the smaller veins, and blood is drained by veins emptying into the vena cavae. This occurs at several sites and may produce clinical signs or symptoms.

 

Sites of Portal-Caval Venous Anastomoses

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The celiac artery gives rise to the common hepatic artery.The common hepatic artery gives rise to the proper hepatic artery.

There are five branches of the hepatic artery: the right gastric, left gastric, gastroduodenal, left hepatic, middle hepatic, and the right hepatic. This group of arteries supplies blood to the pancreas, liver, gallbladder, stomach, and duodenal section within the small intestine.

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The proper hepatic artery ascends in the free edge of the lesser omentum. As it approaches the liver it divides near the portal triad into the left and right hepatic arteries.

The common hepatic artery is a branch of the aorta off the celiac stem of the abdomen. There are five branches of the hepatic artery: the right gastric, left gastric, gastroduodenal, left hepatic, middle hepatic, and the right hepatic. This group of arteries supplies blood to the pancreas, liver, gallbladder, stomach, and duodenal section within the small intestine.

 

The right hepatic artery has a forked shape and supplies blood to the right region of the liver. Typically, the left and right hepatic arteries originate in a fork off the common hepatic artery and are positioned parallel to the portal vein and bile duct.

The right hepatic artery occasionally stems from the superior mesenteric artery. If this occurs, it is referred to as a replaced right hepatic artery. The replaced artery is travels through or behind the pancreatic head, near the main portal vein. In rare cases, it originates from the gastroduodenal artery.

Determining the position of the right hepatic artery is crucial for laparoscopic cholecystectomy, a type of surgery that uses very small incisions, a small camera, and special surgical tools to remove a person’s gallbladder.

The right hepatic artery gives rise to the cystic artery supplying the gallbladder. The right and left hepatic branches enter the liver and divide into lobar, segmental, and smaller branches.

The left hepatic artery supplies the left and quadrate lobes and a portion of the caudate lobe.

Eventually blood reaches the arterioles in the portal areas at the periphery of the hepatic lobules and, after providing oxygen and nutrients to the parenchyma, drain into the hepatic sinusoids. The majority of blood entering the liver is venous blood rich in nutrients and molecules absorbed by the gastrointestinal organs. Intrahepatic branches of the portal vein follow the arteries to the portal areas, where portal venules empty into the sinusoids from which molecules are extracted and added. Sinusoidal blood flows to the central vein of each lobule from which increasingly larger veins are formed until typically three hepatic veins exit the liver to join the IVC.

 

 

As it approaches the liver, it divides into right and left hepatic branches that enter the liver and divide into lobar, segmental, and smaller branches. Eventually blood reaches the arterioles in the portal areas at the periphery of the hepatic lobules and, after providing oxygen and nutrients to the parenchyma, drain into the hepatic sinusoids. The majority of blood entering the liver is venous blood rich in nutrients and molecules absorbed by the gastrointestinal organs. Intrahepatic branches of the portal vein follow the arteries to the portal areas, where portal venules empty into the sinusoids from which molecules are extracted and added. Sinusoidal blood flows to the central vein of each lobule from which increasingly larger veins are formed until typically three hepatic veins exit the liver to join the IVC (Figure 29-2).

The portal system: 1 = portal vein, 2 = superior mesenteric vein, 3 = splenic vein, 4 = inferior mesenteric vein, 5 = superior rectal vein, 6 = right gastroepiploic vein, 7 = left gastric vein, 8 = esophageal vein, 9 = hepatic veins. ( from the University of Texas Health Science Center Houston Medical School.)

The portal venous system arises from the capillary beds within the abdominal organs supplied by the celiac artery, superior mesenteric artery (SMA), and inferior mesenteric artery (IMA), and blood will flow to and through the liver for metabolism of its contained molecules. Veins from these organs for the most part accompany arteries of the same name. The portal vein itself is formed by the union of the splenic vein and SMV posterior to the neck of the pancreas. This short, wide vein ascends within the hepatoduodenal ligament, posterior to the bile duct and hepatic artery, and enters the liver through the porta hepatis. Typically, the IMV drains its blood into the splenic vein.

Portacaval (systemic) venous anastomoses occur at sites where blood may ultimately drain into the portal system and/or the vena caval system. If venous flow through the portal system is prevented by liver disease, for example, the absence of valves within the portal system veins allows reverse flow. This dilates the smaller veins, and blood is drained by veins emptying into the vena cavae. This occurs at several sites and may produce clinical signs or symptoms.

Sites of Portal-Caval Venous Anastomoses

 

The gallbladder lies on the visceral surface of the liver, to the right of the quadrate lobe.

It stores and concentrates bile secreted by the liver.

Bile enters the cystic duct, which joins the common hepatic duct, becoming the common bile duct.

The common bile duct courses within the hepatoduodenal ligament of the lesser omentum, deep to the first part of the duodenum, where it joins the main pancreatic duct.

Together, the common bile duct and the main pancreatic duct enter the second part of the duodenum at the hepatopancreatic ampulla (of Vater).

The sphincter of Oddi surrounds the ampulla and controls the flow of bile and pancreatic digestive enzyme secretions into the duodenum.