Which layer of the skin is primarily affected in a second-degree burn?

A second-degree burn, also known as a partial-thickness burn, primarily affects the dermis, which is the second layer of skin located beneath the epidermis. This type of burn not only damages the outer layer (epidermis) but also penetrates into the dermis, leading to more severe symptoms such as pain, redness, swelling, and blistering.

The involvement of the dermis in second-degree burns is crucial because this layer contains nerve endings, blood vessels, and connective tissue, which play significant roles in sensation and healing. The injury to the dermis is what contributes to the pain and the likelihood of complications and the healing process, as the dermal layer is essential for the skin's structural integrity and its ability to regenerate.

While the epidermis is involved in second-degree burns, the hallmark of such burns is the damage extending into the dermis. The subcutaneous tissue, which lies beneath the dermis, is not affected in second-degree burns. Instead, it is commonly involved in deeper burns, like third-degree burns. Muscle tissue is also not affected in a second-degree burn, as this injury does not penetrate that deeply into the skin layers.