fourth-degree burn

burn (burn) injury to tissues caused by the contact with heat, flame, chemicals, electricity, or radiation. First degree burns show redness; second degree burns show vesication; third degree burns show necrosis through the entire skin. Burns of the first and second degree are partial-thickness burns, those of the third degree are full-thickness burns.

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first-degree burn  a burn that affects the epidermis only, causing erythema without blistering.

fourth-degree burn  a burn that extends deeply into the subcutaneous tissue; it may involve muscle, fascia, or bone.

full-thickness burn  third-degree b.

partial-thickness burn  second-degree b.

second-degree burn  a burn that affects the epidermis and the dermis, classified as superficial (involving the epidermis and the papillary dermis) or deep (extending into the reticular dermis). Called also partial thickness b.

third-degree burn  a burn that destroys both the epidermis and the dermis, often also involving the subcutaneous tissue. Called also full-thickness b.

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fourth-degree burn,

a burn that extends deeply into the subcutaneous tissue, completely destroying the skin, subcutaneous fat, and underlying tendons, and sometimes involving muscle, fascia, or bone.