The major portion of radiation from long infrared is absorbed in the skin layer?

• A. Corium of the skin
• B. Subcutaneous layers of the skin
• C. Stratum corneum
• D. Stratum mucosum

Answer: (A)

Infrared energy interacts with skin most where the tissue has abundant water and vascular content, which is the dermis. Long infrared photons penetrate the outer epidermal layers relatively readily, but the energy is most effectively absorbed by the dermal layer’s water-rich connective tissue and capillaries, turning into heat and warming the underlying tissues. The outermost layer, the stratum corneum, is thin and quite dry, so it doesn’t absorb much of the IR energy. The deeper subcutaneous tissues are reached less because the energy is largely attenuated in the dermis first. That makes the corium (dermis) the primary site of absorption for long infrared.