Liver Sement S2 is Consistently Located at the Dorsal Side of S3 But Sometimes at the Right and/or Caudal Side of S3

Abstract

Summary: After preparing the frontal section including the origin of the left portal trunk at the hilar region, the left anatomical lobes of 111 human livers were dissected to reveal the segmental configuration based on the supplying portal vein branches. S2 was consistently located dorsal to S3. However, in contrast to the description in common textbooks for medical students, 19.8% of the specimens carried a paradoxical segmental configuration showing a "caudal and/or rightward" S2 in combination with a "cranial and/or leftward" S3 in the frontal section through the ventral part of the hilar region. The caudal and rightward cases were associated with a specific arrangement of S2 and S3 segmental stems in which the S3 stem ran relatively upward to spread over S2 or both stems ran almost horizontal, respectively. In routine diagnostic radiology, identification of S2 and S3 might sometimes be biased by the generally accepted notion that S2 should be located at the dorsal, cranial and left side of S3.

Human liver caudate lobe and liver segment

“…S2 is called the lateral superior area, as described by Williams, 1995). In contrast, using specimens with simple bifurcation of the segmental branch of the portal vein P2 and P3, Wakiguchi et al . (2001) reported that S2 is consistently located dorsally to S3 but sometimes (19.8% in 111 livers) medially and/or caudally/inferiorly to S3 in contrast to the usual concept.…”