The falciform ligament anchors the liver to the abdominal wall and divides it into two main lobes.

The falciform ligament is a sickle-shaped fold of peritoneum that connects the liver to the anterior abdominal wall and the diaphragm. It is one of five ligaments that secure the liver, which is the largest internal organ in the human body, typically weighing between 1.2 and 1.5 kilograms in a healthy adult. Anatomically, this ligament serves as the primary landmark that separates the larger right lobe from the smaller left lobe.During embryonic development, the falciform ligament is part of the ventral mesentery. It originally contains the left umbilical vein, which is critical for transporting nutrient-rich and oxygenated blood from the mother's placenta to the fetus. Within one to two weeks after birth, the umbilical vein undergoes a process called fibrosis and closes completely. This collapsed vessel remains as a cord-like structure called the ligamentum teres, or round ligament, located at the free edge of the falciform ligament.Clinically, the falciform ligament is significant because it can become a site for collateral circulation in patients with portal hypertension. If blood flow through the liver is blocked, old fetal pathways can sometimes reopen to divert blood back toward the heart. Surgeons also use the ligament as a vital guide during laparoscopic procedures to identify liver segments and avoid damaging major blood vessels. This transition from a vital blood conduit to a structural support highlights the efficiency of human biological engineering.