- In medicine, there are two types of nails. One is just a plain old metal nail used to hold 2 or more pieces of bone together, for example, after a fracture. The other type of nail is the horny plate on the end of the finger or toe. Each nail anatomically has a body, lateral nail folds (on the sides), a lunula (the little moon-shaped feature at the base), and a proximal skin fold (at the base).
* * *1. One of the thin, horny, translucent plates covering the dorsal surface of the distal end of each terminal phalanx of fingers and toes. A n. consists of corpus or body, the visible part, and radix or root at the proximal end concealed under a fold of skin. The underpart of the n. is formed from the stratum germinativum of the epidermis, the free surface from the stratum lucidum, the thin cuticular fold overlapping the lunula representing the stratum corneum. SYN: unguis [TA], n. plate, onyx. 2. A slender rod of metal, bone, or other solid substance, used in operations to fasten together the fragments of a broken bone. [A.S. naegel]- half and half n. division of the n. by a transverse line into a proximal dull white part and a distal pink or brown part; seen in uremia.- ingrown n. a toenail, one edge of which is overgrown by the nailfold, producing a pyogenic granuloma; due to faulty trimming of the toenails or pressure from a tight shoe. SYN: ingrowing toenail, onychocryptosis, unguis aduncus, unguis incarnatus.- pincer n. transverse overcurvature of the n. that increases distally, causing the lateral borders of the n. to pinch the soft tissue with resulting tenderness; may result from a developmental anomaly or subungual exostosis.- racket n. a broad flat thumbnail resulting from a congenital shorter and wider distal phalanx of the thumb.- reedy n. a n. marked by longitudinal ridges and furrows.- shell n. n. dystrophy accompanying clubbing of digits in bronchiectasis, with excessive longitudinal curvature of the n. plate and atrophy of the n. bed and underlying bone.- yellow n. the complete or almost complete cessation of all n. growth, with thickening of the nails, increase in the convexity, loss of cuticles, and yellowing; the resulting onycholysis can cause loss of some of the nails; the condition is often associated with pulmonary disease but differs from clubbing in that the soft tissues are not hypertrophic. Lymphatic drainage may be reduced, even in the absence of lymphedema. SYN: yellow n. syndrome.
* * *nail 'nā(ə)l n1) a horny sheath of thickened and condensed epithelial stratum lucidum that grows out from a vascular matrix of dermis and protects the upper surface of the end of each finger and toe of humans and most other primates and that is strictly homologous with the hoof or claw of other mammals from which it differs chiefly in shape and size called also nail plate2) a structure (as a claw) that terminates a digit and corresponds to a nail3) a rod (as of metal) used to fix the parts of a broken bone in normal relation <a medullary \nail>
* * *n.a horny structure, composed of keratin, formed from the epidermis on the dorsal surface of each finger and toe. 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.
* * *(nāl) 1. unguis. 2. a rod of metal, bone, or other material used for fixation of the ends or the fragments of fractured bones.
Medical dictionary. 2011.