Nails are produced by living skin cells in the fingers and toes. They are composed primarily of keratin, a hardened protein also found in skin and hair. The nail itself consists of several different parts, including:
- Nail Plate: The visible part of the nail on fingers and toes.
- Nail Bed: The skin beneath the nail plate.
- Matrix: The area under the cuticle, the hidden part of the nail unit where growth takes place.
- Lunula: This is part of the matrix and is the whitish, half-moon shape at the base of the nail, usually most pronounced on the thumb.
- Cuticle: Tissue that overlaps the plate and rims the base of the nail.
- Nail Folds: The folds of skin that frame and support the nail on three sides.
Nails, like hair, grow from the matrix. As older cells grow out, they are replaced by newer ones, they are compacted and take on a hardened form. The average growth rate for nails is 0.1 mm each day; individual rates depend on age, time of year, activity level, and heredity. Fingernails grow faster than toenails. Nails also grow more rapidly in the summer than in the winter. Nails on a person’s dominant hand (right vs. left) grow faster, and men’s nails grow more quickly than women’s, except possibly during pregnancy and old age. Nail growth is affected by disease, hormone imbalance, and the aging process.