What is the protective layer that covers the nail matrix called?

The protective layer that covers the nail matrix is known as the nail fold. The nail fold is a fold of skin that overlaps and surrounds the sides of the nail plate. This structure serves as a barrier that protects the underlying nail matrix, which is the area responsible for producing new nail cells. By safeguarding the matrix, the nail fold helps to prevent injuries and infections from reaching the more delicate tissue beneath.

The nail bed, while also important for nail health, is the skin underneath the nail plate and does not provide the same level of protective coverage for the matrix itself. The cuticle, another significant component in nail health, specifically refers to the layer of dead skin at the base of the nail that protects the matrix, but it does not fully encompass the nail area as the nail fold does. The lunula, which is the visible part of the matrix at the base of the nail, also does not function as a protective cover, but rather is a part of the matrix itself. Thus, the nail fold is most accurately identified as the protective layer surrounding the nail matrix.