n. a threadlike keratinized outgrowth of the epidermis of the skin. It develops inside a tubular hair follicle. The part above the skin consists of three layers: an outer cuticle; a cortex, forming the bulk of the hair and containing the pigment that gives the hair its colour; and a central core (medulla), which may be hollow. The root of the hair, beneath the surface of the skin, is expanded at its base to form the bulb, which contains a matrix of dividing cells. As new cells are formed the older ones are pushed upwards and become keratinized to form the root and shaft. A hair may be raised by a small erector muscle in the dermis, attached to the hair follicle.
Subjects: Arts and Humanities — Medicine and Health.