A burn depth that extends through all layers of skin and into muscle or bone is classified as which degree?

• A. First-degree
• B. Fourth-degree
• C. Second-degree
• D. Third-degree

Answer: (B)

Burn depth classifications describe how far injury penetrates. A burn that goes through all the layers of the skin and into underlying structures like muscle or bone is a fourth-degree burn. First-degree injuries affect only the epidermis and are red and painful but heal quickly. Second-degree injuries involve the epidermis and part of the dermis, with blisters and more pain. Third-degree burns are full-thickness through the skin into deeper tissues of the skin, often appearing white or leathery and may be insensate due to nerve damage. Fourth-degree burns extend beyond the skin into deeper structures such as muscle or bone, and they represent the deepest, most severe burns requiring extensive treatment.