The hepatic artery proper is a major blood vessel that supplies oxygenated blood to the liver. It typically arises from the common hepatic artery, which is a branch of the celiac trunk, itself a major branch of the abdominal aorta. The hepatic artery proper runs toward the liver, supplying it with oxygen-rich blood alongside the portal vein, which brings nutrient-rich blood from the gastrointestinal tract.
Location
The hepatic artery proper is located in the upper right quadrant of the abdomen. It originates from the common hepatic artery after the gastroduodenal artery branches off. It then ascends within the hepatoduodenal ligament, a part of the lesser omentum, and travels toward the liver alongside the portal vein and bile duct. At the level of the porta hepatis (the entry point to the liver), the hepatic artery proper typically divides into the right and left hepatic arteries, which supply their respective lobes of the liver.
Structure and Anatomy
Origin
The hepatic artery proper arises from the common hepatic artery, which is a branch of the celiac trunk. The celiac trunk is one of the three major branches of the abdominal aorta and gives rise to arteries that supply the liver, stomach, and other organs in the upper abdomen. After the common hepatic artery gives off the gastroduodenal artery, the vessel is then called the hepatic artery proper.
Course
Once formed, the hepatic artery proper ascends through the hepatoduodenal ligament, a fold of the peritoneum that is part of the lesser omentum. It runs in close proximity to the common bile duct and portal vein, forming part of the portal triad, which is a crucial structure that travels toward the liver. The hepatic artery proper continues its upward course toward the porta hepatis, the entrance to the liver, where it divides into its terminal branches.
Branches
As the hepatic artery proper ascends toward the liver, it gives off smaller branches and then terminates by dividing into the right and left hepatic arteries, which supply the right and left lobes of the liver, respectively. Some important branches include:
- Right Gastric Artery: The right gastric artery typically arises from the hepatic artery proper and supplies the lesser curvature of the stomach.
- Cystic Artery: In many individuals, the cystic artery, which supplies the gallbladder, arises from the right hepatic artery, a branch of the hepatic artery proper.
Relations
- Anteriorly: The hepatic artery proper is covered by the peritoneum and is in close proximity to the liver and stomach as it ascends toward the porta hepatis.
- Posteriorly: The artery lies in front of the portal vein, one of the main vessels carrying nutrient-rich blood to the liver from the gastrointestinal tract.
- Laterally: The common bile duct runs laterally to the hepatic artery proper as part of the portal triad. These structures are enclosed within the hepatoduodenal ligament, which connects the liver to the duodenum.
Termination
The hepatic artery proper terminates at the porta hepatis, the point where structures enter the liver. Here, it divides into its terminal branches:
- Right Hepatic Artery: This artery supplies the right lobe of the liver and often gives rise to the cystic artery, which supplies the gallbladder.
- Left Hepatic Artery: This artery supplies the left lobe of the liver.
Anatomical Variations
Variations in the hepatic artery proper’s anatomy are common, particularly in its origin and branching pattern. Some common variations include:
- Origin from the Superior Mesenteric Artery: In some individuals, the hepatic artery proper may arise directly from the superior mesenteric artery rather than from the celiac trunk.
- Variation in Branching Patterns: The division of the hepatic artery proper into right and left branches may occur at different levels or angles depending on the individual.
Length and Diameter
The length of the hepatic artery proper is typically short, as it spans the distance between the branching of the gastroduodenal artery and the porta hepatis. Its diameter is relatively large compared to other arteries in the upper abdomen because of its role in supplying a large organ, the liver.
Function
The hepatic artery proper is a critical vessel responsible for delivering oxygenated blood to the liver and adjacent structures, playing a vital role in maintaining the metabolic functions of the liver, bile production, and overall organ health. Below is a detailed breakdown of its specific functions.
Blood Supply to the Liver
The primary function of the hepatic artery proper is to provide oxygenated blood to the liver. While the portal vein supplies nutrient-rich blood from the gastrointestinal tract to the liver, the hepatic artery proper supplies the liver with the oxygen necessary for cellular metabolism and liver function. The liver is a highly metabolic organ that requires oxygen to:
- Perform Metabolic Activities: The liver is involved in various metabolic processes such as glucose metabolism, protein synthesis, and detoxification. The oxygenated blood from the hepatic artery proper ensures that liver cells, or hepatocytes, have the energy to carry out these essential functions.
- Support Detoxification Processes: The liver plays a vital role in detoxifying harmful substances from the blood. The oxygen supplied by the hepatic artery proper supports hepatocytes in breaking down toxins and metabolizing drugs.
- Bile Production: The liver produces bile, which is essential for digestion. The oxygenated blood from the hepatic artery proper helps sustain the bile-producing cells in the liver, ensuring efficient bile production.
Blood Supply to the Gallbladder via the Cystic Artery
The hepatic artery proper indirectly contributes to the blood supply of the gallbladder through the cystic artery, which typically arises from the right hepatic artery, a branch of the hepatic artery proper. The cystic artery supplies oxygenated blood to the gallbladder, enabling it to store bile and release it into the duodenum during digestion. The right hepatic artery, through the cystic artery, ensures that the gallbladder’s muscular walls receive enough oxygen to function properly.
Blood Supply to the Bile Ducts
The hepatic artery proper also supplies blood to the common bile duct through small arterial branches. The bile ducts are responsible for transporting bile from the liver and gallbladder to the small intestine. The blood supply from the hepatic artery proper helps maintain the health and integrity of the bile duct epithelium, ensuring that bile flows smoothly without obstruction. This function is crucial for:
- Maintaining Bile Flow: The bile duct requires an adequate blood supply to maintain its muscular tone, allowing the smooth passage of bile from the liver and gallbladder into the small intestine during digestion.
- Supporting Bile Duct Regeneration: The blood supplied by the hepatic artery proper helps repair and regenerate bile duct cells, especially in cases of injury or inflammation.
Blood Supply to the Liver’s Supporting Structures
Besides supplying oxygen to the liver, the hepatic artery proper also provides blood to the connective tissues and structures surrounding the liver, such as the Glisson’s capsule, a thin layer of connective tissue that surrounds the liver and protects it. This blood supply is essential for maintaining the integrity and support of the liver as it performs its functions.
Role in Collateral Circulation
The hepatic artery proper contributes to the collateral circulation of the liver and nearby organs. In the event of obstruction or blockage in other blood vessels (such as the portal vein), the hepatic artery proper can play a compensatory role by increasing blood flow to the liver and maintaining essential functions. This function is critical for:
- Preventing Ischemia: In cases where the liver’s primary blood supply from the portal vein is compromised, the hepatic artery proper provides a secondary source of oxygenated blood to prevent liver tissue from becoming ischemic (lacking oxygen).
- Supporting Liver Regeneration: The liver has a remarkable capacity to regenerate, and this regenerative process requires a rich supply of oxygenated blood. The hepatic artery proper ensures that the liver can regenerate effectively after injury, partial resection, or transplantation.
Clinical Significance
The hepatic artery proper is clinically significant due to its role in supplying oxygenated blood to the liver, bile ducts, and gallbladder. In liver surgeries, such as liver transplantation, resection, or cholecystectomy, careful identification and preservation of the hepatic artery proper are crucial to prevent ischemia and ensure adequate blood flow to the liver.
In cases of hepatic artery occlusion or injury during surgery, liver function may be severely compromised, leading to ischemic damage, impaired bile production, and liver necrosis. The hepatic artery proper is also involved in liver transplant surgeries, where the artery must be reconnected to ensure proper blood flow to the transplanted liver.
Aneurysms or stenosis of the hepatic artery proper can result in reduced blood flow to the liver and gallbladder, leading to potential complications like ischemic injury, biliary dysfunction, or even liver failure. Understanding its anatomy is essential for successful outcomes in hepatobiliary surgeries and managing vascular conditions affecting the liver.
