The portal vein divides into right and left branches at the porta hepatis. Which structure lies anterior to the portal vein in the hepatoduodenal ligament?

Explanation

## Hepatoduodenal Ligament — Vascular and Biliary Contents **Key Point:** The hepatoduodenal ligament (part of the lesser omentum) contains three major structures arranged in a specific anatomical relationship: the **common bile duct (anteriorly)**, the **hepatic artery proper (anteromedially)**, and the **portal vein (posteriorly)**. ### Mnemonic: **"BAD"** - **B** = Bile duct (anterior) - **A** = Artery (anterior-medial) - **D** = duct (portal vein is posterior — remember "D" for "Deep" or posterior) Alternatively: **"Anterior to Posterior: Bile, Artery, Portal vein"** ### Anatomical Arrangement in Hepatoduodenal Ligament | Structure | Position | Side | Relationship | | --- | --- | --- | --- | | Common bile duct | **Anterior** | Right | Most anterior, most vulnerable to injury | | Hepatic artery proper | **Anterior-medial** | Left/medial | Anterior but medial to bile duct | | Portal vein | **Posterior** | Central | Deepest, most protected | **High-Yield:** In the hepatoduodenal ligament, the **common bile duct is the most anterior structure**. This is clinically critical because: 1. It is most vulnerable to iatrogenic injury during cholecystectomy 2. It is the first structure encountered when opening the hepatoduodenal ligament 3. In Calot's triangle (bounded by cystic artery, cystic duct, and liver edge), the bile duct is NOT part of the triangle but lies anterior to it **Clinical Pearl:** During laparoscopic cholecystectomy, the "critical view of safety" requires identification of two structures crossing the hepatocystic triangle — the cystic artery and cystic artery alone. The common bile duct lies outside (anterior to) this triangle and should NOT be divided. **Warning:** ~~The hepatic artery is the most anterior structure~~ — INCORRECT. The common bile duct is anterior; the hepatic artery is anteromedial but deeper than the bile duct.