**Question:** Ligamentum teres develops from

A. portal vein
B. umbilical artery
C. portal vein and umbilical artery
D. hepatic artery

**Core Concept:** Ligamentum teres is a small, round ligament located within the hepatobiliary system, connecting the liver to the gallbladder and right hepatic lobe.

**Why the Correct Answer is Right:** Ligamentum teres develops from the fusion of two embryonic structures: the right and left cardial cords, which are extensions of the umbilical arteries. These cords derived from the cardial cords of the embryonic gut and join to form the ligamentum teres.

**Why Each Wrong Option is Incorrect:**

A. Portal vein: Portal vein is a large vessel carrying deoxygenated blood from the intestines to the liver, and does not contribute to the development of ligamentum teres.

B. Umbilical artery: Umbilical artery is a small vessel carrying oxygenated blood from the placenta to the fetus and does not participate in the formation of ligamentum teres.

C. Portal vein and umbilical artery: Both portal vein and umbilical artery are incorrect sources for ligamentum teres formation, as explained above for options A and B.

**Why Option D is Incorrect:** D. Hepatic artery is a branch of the celiac trunk, carrying oxygenated blood to the liver and gastrointestinal tract. It does not participate in the development of ligamentum teres.

**Clinical Pearl:** Understanding the embryonic origins of ligamentum teres helps to appreciate the anatomy and development of the hepatobiliary system. This knowledge is crucial for interpreting imaging studies (e.g., ultrasound, CT, MRI) in clinical practice, particularly when evaluating conditions involving the hepatobiliary system like cholelithiasis (gallstones) or choledocholithiasis (gallstone in the common bile duct).

**Correct Answer:** D. Hepatic artery is incorrect as it does not contribute to the formation of ligamentum teres. The correct answer is C. Portal vein and umbilical artery, as they are the embryonic structures that fuse together to form ligamentum teres.