Anatomy and Growth Rate of the Fingernail

Abstract

As illustrated in Figures 2 and 3, the nail consists of the nail plate and the tissues which surround and underlie it (Pillsbury, Shelley, and Kligman, 1956, p. 32). The nail plate is composed of hard keratin, a protein that is synthesized by the nail-forming tissue called the matrix. The average daily rate of linear nail growth is approximately .1 mm (Morton, 1962; Norton, 1975; Pillsbury et al., 1956); this nail-forming tissue is in a highly active metabolic state and is very sensitive to local or generalized physiological alterations, such as trauma to the nails, localized infection, or disease. The nail plate itself is an inert structure that consists of three main parts: (a) the root, which is beneath the skin; (b) the fixed portion, which is firmly attached to the underlying nail bed; (c) the free edge of the nail, which extends beyond the distal-most point of attachment of the nail plate to the nail bed (Pillsbury et al., 1956).