ligamentum teres

Embryologically, the ligamentum teres hepatis develops from the obliterated left umbilical vein after birth, once placental circulation ceases. It travels within the free margin of the falciform ligament, connecting the umbilicus to the porta hepatis, and serves as an important anatomic landmark separating the liver into segments (used in Couinaud classification correlating with the left intersegmental fissure). Clinically, in portal hypertension, increased pressure in the portal system can cause recanalization of this obliterated vein, leading to portosystemic shunting and the clinical sign of caput medusae (dilated periumbilical veins) along with possible venous hum (Cruveilhier-Baumgarten syndrome). The ligamentum venosum, a related structure, is the remnant of the fetal ductus venosus and separates the caudate lobe from the left lobe. Separately, the ligamentum teres femoris (ligament of the head of femur) is an intra-articular ligament of the hip joint, transmitting the obturator artery's acetabular branch, which is a significant blood supply to the femoral head in children (before the medial circumflex femoral artery becomes dominant). Disruption of this ligament or its vessel is relevant in avascular necrosis discussions, hip dislocations, and pediatric orthopedics (e.g., Legg-Calvé-Perthes disease pathophysiology involves compromised blood supply, partly via this ligament in younger children).