Human nails

The fingernails and toenails originate as inward growths of epidermis. In this respect they are similar to hair follicles. But, in the case of the nails, the inward growth begins as a broad fold of the basal layer of the epidermis at the end of the digits.

The deeper infolded tissues form a region of actively dividing cells known as the nail matrix.

As nail cells are formed by the matrix they are pushed from the root of the nail to the surface and forward to add to the exposed nail plate.

A region of thickened epithelium beneath the base of the nail can be seen from the surface as the lunula – the pale crescent at the nail base.

The nail bed consists of epidermal and dermal tissues beneath the nail plate beyond the lunula. The blood supply of the dermis is closer to the surface here and causes the darker color in the portion of the nail past the lunula.

The eponychium of the nail is commonly called the cuticle. It consists of an outward fold of the epidermis above the base of the nail plate.

The hyponychium of the nail is a thickened epidermis zone beneath the free edge at the end of the nail, just distal to the nail bed.