toenail

toenail A tough, protective plate that is produced by living skin cells in the toe. A toenail consists of several parts, including the nail plate (the visible part of the nail), the nail bed (the skin beneath the nail plate), the cuticle (the tissue that overlaps the plate and rims the base of the nail), the nail folds (the skin that enfolds the frame and supports the nail on three sides), the lunula (the whitish halfmoon at the base of the nail), and the matrix (the hidden part of the nail unit under the cuticle). Toenails grow from the matrix. They are composed largely of keratin, a hardened protein that is also found in fingernails, skin, and hair. As new cells grow in the matrix, the older cells are pushed out and compacted, taking on the flattened, hardened form of the toenail. The average growth rate for toenails is 0.1 mm per day. The exact rate of nail growth depends on numerous factors, including the age and sex of the individual and the time of year. Toenails generally grow fastest in young people, in males, and in the summer. Toenails grow more slowly than fingernails. See also nail; nail care.