## Rule of Nines in Adult Burns **Key Point:** The Rule of Nines is a rapid method to estimate total body surface area (TBSA) affected by burns in adults. It divides the body into segments, each representing 9% or a multiple of 9%. ### Adult Body Surface Area Distribution | Body Region | Percentage | |---|---| | Head and neck | 9% | | Each upper limb | 9% | | Anterior trunk | 18% | | Posterior trunk | 18% | | Each lower limb | 18% | | Genitalia | 1% | | **Total** | **100%** | **High-Yield:** Each lower limb in an adult represents **18%** of TBSA (9% anterior thigh + 9% anterior leg + foot, and similarly posterior). This is a commonly tested fact in forensic medicine and burn management. **Clinical Pearl:** The Rule of Nines is less accurate in children. In infants, the head represents 18% and each lower limb represents 14%, reflecting the proportionally larger head and smaller limbs. **Mnemonic:** **"Rule of 9s"** — Head 9%, each arm 9%, anterior trunk 18%, posterior trunk 18%, each leg 18%, perineum 1%.
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.