Caption:
A diagram of illustrated sections of skin with different burn degrees. First degree burns (top) only affect the epidermis, the superficial layer of skin, and are commonly caused by sunburns. Second degree burns extend to deep portions of the dermis and are accompanied by the formation of blisters. Third and fourth degree burns extend beyond the epidermis and dermis to underlying layers of fat, muscle or bone, and require excision or amputation of affected regions.