What anatomical feature determines the shape of the nail plate?

The shape of the nail plate is primarily determined by the matrix. The matrix is the tissue located beneath the base of the nail, where new nail cells are produced. As these cells multiply and grow, they push older cells forward, leading to the formation of the nail plate that we see. The characteristics and quality of the matrix influence not only the shape but also the overall health and growth rate of the nail.

The nail bed serves as the area beneath the nail plate that supports it, but it does not actively influence the nail's shape. The lunula, the visible part of the matrix at the base of the nail, can provide some visual clues about nail health but is not directly responsible for determining the overall shape. The cuticle, which is the layer of skin at the base of the nail, protects the matrix but does not contribute to the formation of the nail plate itself.