## Anatomy of Calot's Triangle ### Definition and Boundaries **Key Point:** Calot's triangle (hepatocystic triangle) is a critical anatomical landmark in biliary surgery, bounded by three structures: | Boundary | Structure | | --- | --- | | Medial | Common hepatic duct | | Superolateral | Cystic duct | | Inferior | Liver bed / hepatic surface | ### Contents of Calot's Triangle **High-Yield:** The cystic artery is the principal neurovascular structure within Calot's triangle. It typically: - Arises from the right hepatic artery (most common, ~75% of cases) - Lies anterior to the common hepatic duct - Is the first vessel ligated during open or laparoscopic cholecystectomy - May have anomalous origins in 25% of cases (left hepatic, gastroduodenal, or replaced arteries) ### Why Option 3 is Incorrect **Warning:** The right hepatic artery does NOT form a boundary of Calot's triangle. Although the cystic artery (a branch of the right hepatic artery) lies within the triangle, the parent vessel itself is located posterior and medial to the triangle. The triangle's superior boundary is the cystic duct, not the right hepatic artery. ### Clinical Significance **Clinical Pearl:** During cholecystectomy, the "critical view of safety" technique requires clear identification of: 1. Two structures crossing the hepatocystic triangle (cystic artery and cystic duct) 2. Clear liver bed with no additional structures 3. Absence of inflammation obscuring anatomy This prevents inadvertent ligation of the common hepatic duct or right hepatic artery, which would cause biliary or hepatic ischemia respectively. **Mnemonic:** **CHD** = Calot's triangle contains Hepatic artery (cystic branch) and Duct (cystic). The medial boundary is the Common Hepatic Duct.
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