Final answer:
The eponychium, also known as the nail cuticle, is the living skin at the base of the natural nail plate covering the matrix area. It protects the nail matrix where the new nail cells are created.
Step-by-step explanation:
The living skin at the base of the natural nail plate covering the matrix area is the eponychium, also known as the nail cuticle. A common mistake is to refer to the cuticle directly as the overlapping layer of dead cells surrounding the nail body, but the eponychium specifically includes the living tissue. In contrast, the cuticle is a layer of dead epithelial cells that overlaps and covers the edge of the nail plate.
The nail matrix is the area where new nail cells are produced, resulting in nail growth. The nail body is the main keratinous plate forming the visible nail, while the nail root is embedded deep in the epidermis. Overall, the eponychium serves an important role in protecting the matrix and the new nail cells developing within it.