Which of the following structures forms the medial border of Calot's triangle?

Explanation

## Anatomy of Calot's Triangle **Key Point:** Calot's triangle (hepatocystic triangle) is a crucial anatomical landmark bounded by three structures: | Border | Structure | | --- | --- | | **Medial** | Common bile duct | | **Lateral** | Cystic artery | | **Superior** | Right hepatic artery | ### Clinical Significance **High-Yield:** The common bile duct forms the medial boundary of Calot's triangle. This triangle is the operative field during cholecystectomy, and the cystic artery (lateral border) is typically identified and ligated first to prevent backbleeding before dissection of the triangle's contents. **Clinical Pearl:** A lymph node may be present within Calot's triangle (Lund's node or Calot's node), which can be mistaken for pathology during surgery. Knowledge of normal anatomy prevents iatrogenic injury to the common bile duct. **Warning:** Misidentification of the common bile duct as the cystic artery during surgery can lead to bile duct ligation—a serious intraoperative complication. Always confirm the three boundaries before proceeding with dissection. ### Mnemonic **CAB Triangle** = **C**ommon bile duct (medial), **A**rtery cystic (lateral), **B**ranch hepatic right (superior).