eponychium
Thickened layer of skin surrounding fingernails and toenails. Beneath the cuticle is a thin layer of a membrane known as the pterygium. The function is to protect the area between the nail and epidermis from exposure to harmful bacteria. The vascularization pattern is similar to that of perionychium. The eponychium is the end of the proximal fold that folds back upon itself to shed an epidermal layer of skin onto the newly formed nail plate. This layer of non-living, almost invisible skin is the cuticle that 'rides out' on the surface of the nail plate. Together, the eponychium and the cuticle form a protective seal. The cuticle on the nail plate is dead cells and is often removed during manicure, but the eponychium is living cells and should not be touched.[6] The perionyx is the projecting edge of the eponychium covering the proximal strip of the lunula[WP].