Heating and cooling occurs to what depth?

• A. 0-1 cm
• B. 5-10 cm
• C. 1-3 cm
• D. 10-20 cm

Answer: (C)

The main idea is that topical heating or cooling does not penetrate very deeply into tissue. Heat or cold applied at the skin surface causes temperature changes that fade with depth because conduction through skin and subcutaneous tissues, plus the cooling effect of blood flow, limits how deep the effect can reach. In typical therapeutic settings, these surface modalities produce meaningful temperature changes only a short distance beneath the skin—about 1 to 3 centimeters. That’s why 1–3 cm is the best answer: it reflects the common depth range where heating or cooling from these methods actually occurs. Depths like 0–1 cm miss the portion of tissue a bit deeper that still experiences temperature change, and depths like 5–10 cm or 10–20 cm are beyond what superficial heating or cooling can affect.