What is Liver Anatomy?
The liver is the body's largest internal organ, divided into lobes and functional segments that surgeons and radiologists use as a map. Understanding its lobes, segments, and hilum is key to grasping liver function, blood supply, and surgical anatomy.
The liver has two main lobes (right and left) split by the falciform ligament, and is further divided into 8 functionally independent Couinaud segments based on blood supply and bile drainage. The hilum (porta hepatis) is where the portal vein, hepatic artery, and bile duct enter or exit.
- •Segments V, VI, VII, VIII
- •Larger of the two lobes
- •Receives the right branch of the portal vein and hepatic artery
- •Segments II, III, IV
- •Smaller, crosses the midline
- •Segment I (caudate) drains independently into the vena cava
Step-by-step worked examples
A surgeon plans to remove segments V and VIII due to a tumor. Which lobe do these belong to, and what major structure is at risk near the hilum?
Segments V and VIII are part of the right lobe (Couinaud classification). The portal triad (portal vein, hepatic artery, bile duct) passes through the porta hepatis and must be carefully preserved for the remaining segments.
A patient's CT scan shows the falciform ligament dividing two structures. What does this ligament anatomically separate?
The falciform ligament is a peritoneal fold connecting the liver to the anterior abdominal wall. It marks the anatomical division between the right and left lobes of the liver, though not the true functional/vascular division.
Identify the three structures that enter or exit the liver at the hilum (porta hepatis).
The porta hepatis is the liver's 'gateway.' It contains the portal vein (inflow, nutrient-rich blood from the gut), the hepatic artery (inflow, oxygenated blood), and the common hepatic duct (outflow, bile).
Flashcards
Quick quiz
Q1.How many functional segments does the liver have in the Couinaud classification?
Q2.What structure separates the right and left anatomical lobes of the liver?
Q3.Which structures pass through the hilum (porta hepatis)?
Q4.Which Couinaud segment is the caudate lobe?
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Common mistakes
Assuming the falciform ligament marks the true functional division of the liver. — Correct: The functional (vascular) division follows Cantlie's line, not the falciform ligament.
Thinking the liver has only 2 segments (right and left lobe). — Correct: It has 8 independently functioning Couinaud segments, each with its own vessels and duct.
Confusing the hilum with the gallbladder fossa. — Correct: The hilum (porta hepatis) is where the portal triad enters/exits; the gallbladder sits in a separate fossa.
Believing the caudate lobe belongs exclusively to the right or left lobe. — Correct: The caudate lobe (segment I) is anatomically distinct and drains directly into the vena cava.
FAQ
What is liver anatomy divided into?
The liver is divided into a right and left lobe, and further into 8 Couinaud segments based on vascular and biliary supply.
What is the hilum of the liver?
The porta hepatis, or hilum, is where the portal vein, hepatic artery, and common hepatic duct enter and exit the liver.
How many segments does the liver have?
Eight functionally independent segments, numbered I through VIII in the Couinaud classification.
Why is liver segmental anatomy important?
It lets surgeons plan resections, like removing a tumor, along segment boundaries without damaging the blood supply of the remaining liver.