Final answer:
The ligamentum venosum separates the caudate lobe (segment I) from the left lobe of the liver and is the fibrous remnant of the ductus venosus that shunted blood in fetal development.
Step-by-step explanation:
The ligamentum venosum is a fibrous remnant of the ductus venosus, which during fetal development shunts oxygenated blood from the placenta away from the semifunctional liver and towards the heart. After birth, the ductus venosus closes and forms the ligamentum venosum, which separates the caudate lobe of the liver (segment I) on the right from the left lobe. The liver is anatomically divided into lobes, and these lobes are further divided both externally by peritoneal folds (ligaments) and internally by hepatic blood vessels and bile ducts.
The liver's right lobe is also internally subdivided into an inferior quadrate lobe and a posterior caudate lobe, defined by features like the ligamentum venosum and the hepatic veins. The ligamentum venosum is a significant anatomical feature within this segmentation of the liver, which plays a role in surgical procedures and the diagnosis of liver diseases.