Triangle of safety refers to the safe area for insertion of chest drain usually for management of pneumothorax or hemothorax. The margins of triangle of safety are: - lateral border of pectoralis muscle anteromedially - horizontal line at the level of nipple making the base of the triangle - anterior border of latissimus dorsi posteriorly Reference: https://link.springer.com/chapter/10.1007/978-3-642-20641-2_62 Image via: https://www.researchgate.net/publication/268987947_Tube_thoracostomy_chest_tube_implantation_and_follow_up/figures?lo=1&utm_source=google&utm_medium=organic