n. a horny structure, composed of keratin, formed from the epidermis on the dorsal surface of each finger and toe (see illustration). The exposed part of the nail is the body, behind which is the root. The whitish crescent-shaped area at the base of the body is called the lunula. Growth of the nail occurs at the end of the nail root by division of the germinative layer of the underlying *epidermis (which forms part of the matrix). The growing nail slides forward over the nail bed. The fold of skin that lies above the root is the nail fold; folds of skin on either side of the nail are the nail walls. The epidermis of the nail fold that lies next to the nail root is called the eponychium (forming the ‘cuticle’ at the base of the nail). Anatomical name: unguis.... nail
Health Encyclopedia