Lobar Anatomy

Abdominal visceral organs including the liver

Just like the lung the liver is divided into segments (like everyone knows that the lung is divided into segments). With the advent of Ultrasound we are able to distinguish these individual vascular planes. The liver is divided by the blood vessels that drain each lobe

Here are some quick facts:

  • There are 2 Anatomical Lobes. Right and Left.
  • 4 Primary liver lobes. Right, Left, Caudate, Quadrate (this is the one everyone forgets).
  • The majority of liver is on the right side of the abdomen.
  • Segmental Anatomy. The 9 segments that we know are subdivided according to the vascular/biliary supply.

Caudate Lobe sits between the IVC and the Left lobe of the liver. It is bordered anteriorly by the Ligamentum Venosum.

Quadrate Lobe sits between the Gallbladder on the right and the Left lobe of the liver.

Couinaud classification

  1. Caudate (Posterior)
  2. Left Superior Lateral
  3. Left Inferior Lateral
  4. Left Hemiliver (4a Superior, 4b inferior)
  5. Right Inferior Medial
  6. Right Inferior Lateral
  7. Right Superior Lateral
  8. Right Superior Medial

Many ask “why do I hear there are 8 sections in one text and 9 sections in another?”. There are 8 sections but section 4 is divided into part “A” and “B” according to Bismuth.
The main purpose for these divisions are surgical. You can remove one of the sections without compromising the rest.


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I am the founder and lead Instructor here at ExamRefresh.com. I strive to help those that are entering the field of Ultrasound to be the best that they can be. Ultrasound is my passion.

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