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1. a rod of metal, bone, or other material used for fixation of the ends of fractured bones.
2. a hardened or horny cutaneous plate overlying the dorsal surface of the distal end of a finger or toe. The nails are part of the outer layer of the skin and are composed of hard tissue formed of keratin. Called also unguis.
Parts of the nail. From Dorland's, 2000.
Nail abnormalities. From Lammon et al., 1996.
ingrown nail see ingrown nail.
spoon nail a nail with a concave surface.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


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 nail 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 nail is formed from the stratum germinativum of the epidermis, the free surface from the stratum lucidum, and the thin cuticular fold overlapping the lunula representing the stratum corneum. Synonym(s): unguis [TA], nail plate, onyx
2. A rod of metal or other solid substance, used in operations to fasten together the fragments of a broken bone.
[A.S. naegel]
Farlex Partner Medical Dictionary © Farlex 2012


1. A slender rod used in operations to fasten together the divided extremities of a broken bone.
2. A fingernail or toenail.
3. A claw or talon.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


Orthopedics A cylindrical metal device constructed of stainless steel used to hold 2 or more pieces of fractured bone in place
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.


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 nail consists of a visible corpus or body, and a radix or root at the proximal end concealed under a fold of skin. The under part of the nail is formed from the stratum germinativum of the epidermis, and the free surface from the stratum lucidum, with the thin cuticular fold that overlaps the lunula representing the stratum corneum.
2. A slender rod of metal, bone, or other solid substance, used in operations to fasten together the divided extremities of a broken bone.
Synonym(s): unguis [TA] , nail plate, onyx.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


1. A rod made of metal, bone, or other solid material used to attach the ends or pieces of broken bones.
Enlarge picture
2. A horny cell structure of the epidermis forming flat plates upon the dorsal surface of the fingers and toes. Synonym: onyx; unguis See: illustration

A fingernail or toenail consists of a body composed of keratin (the exposed portion) and a root (the proximal portion hidden by the nail fold), both of which rest on the nailbed (matrix). The latter consists of epithelium and corium continuous with the epidermis and dermis of the skin of the nail fold. The crescent white area near the root is called the lunula. The epidermis extending from the margin of the nail fold over the root is called eponychium; that underlying the free border of the distal portion is called hyponychium.

A nail grows in length and thickness through cell division in the stratum germinativum of the root. The average rate of growth in fingernails is about 1 mm per week. Growth is slower in toenails and slower in summer than in winter. Nail growth varies with age and is affected by disease and certain hormone deficiencies. The onset of a disease that briefly interferes with nail growth and development may be estimated by measuring the distance of the line (Beau line) across the nail from the root of the nail.

Differential Diagnosis

Changes in the nails, such as ridges, may occur after a serious illness or indicate defective nutrition. In achlorhydria and hypochromic anemia, excessively spoon-shaped nails that are depressed in the center may occur. In chronic pulmonary conditions and congenital heart disease, a spongy excess of soft tissue at the base of the nails may be associated with clubbed fingers. See: clubbing

Atrophy may occur as a result of hereditary or congenital tendencies. Permanent atrophy may follow injuries, scars from disease, frostbite, nerve injuries, and hyperthyroidism. Nail shedding is due to the same causes. Fragile or split nails often occur as a congenital condition or may be due to prolonged contact with chemicals or too frequent buffing or filing of the flat surface of the nail during manicuring. In a healthy person brittle nails are usually caused by exposure to solvents, detergents, and soaps. The brittleness disappears when the external causes are avoided. Dry, malformed nails may be due to trophic changes resulting from injury to a nerve or a finger or from neuritis, Raynaud disease, pulmonary osteoarthropathy, syphilis, onychia, scleroderma, acrodermatitis, or granuloma fungoides of the fingers. Transverse lines (Beau lines) may result from previous interference of nail matrix growth. These lines may be caused by local or systemic conditions. The approximate date of the lesion may be determined because it takes 4 to 6 months for the fingernail to be replaced. Chancre may be suspected if a small indolent ulcer appears near the nail, esp. if indurated and associated with enlarged lymph glands above the inner condyle. Quincke capillary pulsation, indicated by a rhythmic flushing and blanching under the nails, is seen most frequently in aortic regurgitation and often in anemia.

Discoloration of nails is seen in various medical conditions. Black discoloration may be seen in diabetic and other forms of gangrene. Blue-black discoloration is a common condition due to hemorrhage caused by bleeding diseases, such as hemophilia, or trauma. This condition may be painful and can be relieved by drilling a small hole in the nail at the site of the hemorrhage. A dental drill, the heated tip of a paper clip, or a similar rigid wire of small diameter may be used. Brown discoloration may be due to arsenic poisoning. Brownish-black discoloration often indicates chronic mercury poisoning due to the formation of sulfide of mercury in the tissues. Cyanosis of the nails usually indicates anemia, poor circulation, or venous stasis. Green staining of the nail fold or under the nail is associated with the growth of Pseudomonas in a wet area. Slate discoloration is an early manifestation of argyria, and intake of silver should be stopped at once. White spots or striate lesions may be due to trauma and are more frequently seen in women. Transverse white bands in all nails may be a sign of acute or chronic arsenic poisoning or, rarely, of thallium acetate poisoning. See: Mees lines

eggshell nail

A condition in which the nail plate is soft and semitransparent, bends easily, and splits at the end. The condition is associated with arthritis, peripheral neuritis, leprosy, and hemiplegia. It may be the only visible sign of late syphilis.

fungal infection of nail

See: infection

habit deformity nail

Disruption of the nail surface by the habit of abrading or stroking that area. This produces a wavy or washboard-like nail surface.

hang nail

Broken epidermis at the edge of a nail.

ingrown nail

Growth of the nail edge into the soft tissue, causing inflammation and sometimes an abscess. Ingrown nails may be due to improper paring of the nails or pressure on a nail edge from improperly fitted shoes. In many cases, this condition may be prevented by cutting the nails straight across.

intramedullary nail

A surgical rod inserted into the intramedullary canal to act as an immobilization device to hold the two ends of a fractured long bone in position.

reedy nail

A nail marked by longitudinal fissures.

Smith-Petersen nail

See: Smith-Petersen nail

splitting nail

A troublesome condition in which the brittle nails split easily. Polishing, buffing, or abrading the nail surface will weaken the nail; thus, these practices should be discouraged. Brittle nails should be soaked, preferably in bath oil, prior to cutting them.

spoon nail

A nail with a depressed center and elevated lateral edges. This condition may follow trauma to the nail fold or iron deficiency anemia or may develop naturally.
See: koilonychia for illus.
Medical Dictionary, © 2009 Farlex and Partners


1. A protective and functional plate of a hard, tough protein, KERATIN, lying on the back surface of the last PHALANX of each finger and toe.
2. A steel rod used surgically to secure bone fragments in apposition.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005


a horny, keratinized layer protecting the distal end of each finger and toe in humans and most other primates. In other terrestrial vertebrates the nail is shaped into a claw or amalgamated into a hoof.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005


1. One of the thin, horny, translucent plates covering dorsal surface of distal end of each terminal phalanx of fingers and toes.
2. Generally, a metal rod, used in operations to attach fragments of a broken bone.
Medical Dictionary for the Dental Professions © Farlex 2012

Patient discussion about nail

Q. My nails are black- is it dangerous? Hi, I was diagnosed with colon cancer and now I receive chemotherapy. This morning I found that my nails are brown and blue, and other nails have white lines on them. Is that dangerous? Should go and see a doctor?

A. The chemo can cause several changes in your nail, e.g. make them brittle etc. You can find some more info at :

Q. my guy friend has a very sick looking toe nail, what should he do? its really thick and has ridges, its also dark yellow and it looks to me has thick toe jam too... ugh, he needs your help please!

A. It sounds like Toenail fungus. Symptoms of toenail fungus, which can be caused by several types of fungi, include swelling, yellowing, thickening or crumbling of the nail, streaks or spots down the side of the nail, and even complete loss of the nail. Toenail color can vary from brown or yellow to white with this condition. I suggest your friend goes to see a foot doctor. The doctor might remove as much of the nail as possible by trimming, filing or dissolving it. Medicated nail polish might be prescribed for a localized infection, but a serious infection will likely be treated with a prescription oral antifungal medication. Only in severe cases will surgical removal of the nail be recommended.

Q. what natural cure for toe nail fungus really works?

A. Haven't heard about anything natural that was actually provent in reliable, well controlled trial. Especially since natural medications usually aren't tested in this way, I'm not sure there can be an accurate and true answer for this question.

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The ATA is in the process of nailing down a national headquarters and training center in Broward County, Florida, and has assembled its first ever national team.
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A JEALOUS husband kept his wife and children locked up in their home for TWO YEARS - even nailing down the windows and covering them in foil.