Which liver segments are divided by the falciform ligament?

The Falciform Ligament Divides Segments III and IV

The falciform ligament divides segments III and IV of the liver. 1

Anatomical Basis of Liver Segmentation

• The liver is divided into eight functional segments according to the Couinaud classification system, which is based on the vascular inflow, outflow, and biliary drainage 1, 2
• These segments are numbered in a counterclockwise manner when viewing the liver from its inferior surface, starting with segment I (caudate lobe) 3
• The liver can be further divided into sectors based on anatomical landmarks and vascular supply 4

The Falciform Ligament as an Anatomical Landmark

• The falciform ligament is a double peritoneal fold that serves as an important anatomical landmark separating the left and right hepatic lobes 5
• More specifically, the falciform ligament divides segment III (part of the left lateral section) from segment IV (part of the left medial section) 1, 2
• This ligament extends from the anterior abdominal wall to the liver's diaphragmatic surface and contains the ligamentum teres (round ligament) 5, 6

Clinical Significance of the Falciform Ligament

• Understanding the relationship between the falciform ligament and liver segments is crucial for surgical planning, especially in:

  • Liver resections and transplantation 1
  • Split liver transplantation where segment IV viability is a concern 2
  • Evaluation of liver segments for biopsy or targeted interventions 3

• In split liver transplantation, the arterial blood supply to segment IV requires special consideration as it may receive supply from both right and left hepatic arteries 2

• The falciform ligament contains lymphatic vessels and "stomata" (openings) that connect the peritoneal cavity with lymphatic capillaries, which has implications for the spread of infection and tumors 6

Surgical Considerations

• In liver transplantation procedures, especially split liver transplantation, the anatomical relationship between segments III and IV divided by the falciform ligament is a critical consideration 1
• When performing left hepatectomy, surgeons must be aware that the falciform ligament marks the division between segments III and IV, with segment IV typically being preserved in right-sided resections 1
• In living donor liver transplantation, the right lobe (segments V to VIII) and left lobe (segments I to IV) are considered separately, with the falciform ligament serving as an important landmark 1

Radiological Assessment

• Modern imaging techniques including CT, MRI, and endoscopic ultrasound can identify the falciform ligament and help delineate liver segments for surgical planning 3
• The falciform ligament is an important radiological landmark that helps in the identification and differentiation of segments III and IV 2, 3