Nail (anatomy)
From Free net encyclopedia
- This article discusses the anatomical nails. For other uses of the term, see nail.
Image:Fingernails.jpg Image:Fingernail label.jpg
In anatomy, a nail is a horn-like piece at the end of an animal finger or toe. See also claw.
Fingernails and toenails, which are made of protein and are a form of modified hair, are composed of:
- the nail matrix or the root of the nail - this is the growing part of the nail still under the skin at the nail's proximal end.
- eponychium or cuticle which is the fold of skin at the proximal end of the nail.
- paronychium which is the fold of skin on the sides of the nail.
- hyponychium which is the attachment between the skin of the finger or toe and the distal end of the nail.
- nail plate which is what we think of when we say nail, the hard and translucent portion, composed of keratin.
- nail bed which is the adherent connective tissue that underlies the nail.
- lunula which is the crescent shaped whitish area of the nail bed.
Fingernails require 3 to 6 months to regrow completely. Toenails require 12 to 18 months. Any major illness will cause a groove to form in the nails, marking in time the past medical history of its owner. These are called Beau's lines.
Nails grow at an average rate of 0.1 mm/day (1 cm every 100 days) Template:Ref. The average is not constant, though, and actual growth rate is dependent upon age, season, exercise level, and hereditary factors.
Nails can have small white spots (leukonychia), become thickened (onychogryphosis), loosened (onycholysis), infected with fungus (onychomycosis) or degenerative (onychodystrophy); for further information see nail diseases.
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Care
A manicure or pedicure is a health and cosmetic procedure to groom, trim, and paint the nails. It is accomplished with cuticle scissors, nail scissors, nail clippers, and nail files, among various other tools. To paint the nails, nail lacquer (also known as nail polish or fingernail polish) is manually applied and allowed to dry. In 2003 the first ink nail printer NailJet Pro was released. It allowed individuals to print custom hi-resolution colour images on their nails.Template:Ref
In some parts of Asia, similar but larger nail-art printers have been set up near bookstores and other popular destinations of young people. They work much like picture-taking booths.
Small white spots, called leukonychia, may appear on nails as a result of nutrient deficiencies, certain illnesses, or local injury.
Some viruses can infect the toe if not cleaned out at least once a week with peroxide. Toe infections can come from dirty socks, walking barefoot and exposing one's feet in a moldy environment.
Biting
Many people bite their nails. It is uncannily addicting and is often used to relieve stress. Biting one's nails can indicate internal tension or stress.
However, biting the nails can result in the transportation of germs that are buried under the surface of the nail into the mouth. In fact, nail salons use tools that potentially affect a human in a similar way. Regarding nail tools such as files, "If they're used on different people, these tools may spread nail fungi, staph bacteria or viruses," warns Rick Lopes, a spokesperson for the California Board of Barbering and Cosmetology.Template:Ref In fact, over 100 bacterial skin infections in 2000 were traced to footbaths in nail salons. Thus, one can see that many pathogens have the ability to live beneath a nail, and because of this biting the nails can potentially cause health issues.
Fashion and culture
In the late 20th century, artificial nails for women became widely popular. The artificial nails are not a replacement, but an extension for natural nails. There are two main approaches to creating artificial nails—tips and forms. Tips are lightweight plates that are glued on the natural nail. Forms are fit over the nail and then an artificial nail is molded and the form is removed. With both approaches several materials can be used to glue the tips of form artificial nails. One popular material is acryl—a mixture of powder and ethymethacrylate that hardens in 30–40 seconds after application. Acryl can be removed in 20 minutes using a variety of solvents. Another material, gel, hardens under ultraviolet light and is more lasting and more expensive. It can only be removed by cutting it off. Other materials can be used, as well as combinations of them. There are also cheaper flexible tips that can be quickly glued at home without help from a professional. Artificial nails are produced in a variety of colours and can use "special effects" such as contours and sparkles.
In some Asian cultures men may also grow long fingernails, or only the nail on the little finger, to show that they do not do much manual labor, but instead work in an office setting.
Some guitar players, notably classical and fingerstyle players, will purposely grow long nails on the hand they use to pluck the strings. Their longer nails serve as small, easily-maneuverable guitar picks. Care thereof becomes a daily ritual and a mark of pride. Though this attention may seem effeminate, it is a mark of the dedication that accompanies the serious musician.
Someone whose occupation is to cut any type of nail, give artificial nails (or "nail arts") and care nails is generally called a nailist. The place where a nailist works is generally called a nailshop (or "nail shop") or a nailsalon (or "nail salon").
Shridhar Chillal holds the world record for the longest fingernails. They haven't been cut since 1958, and in 2005 they measured 7.21 metres (about 150 cm per nail). (Source: Guinness WR)
Growth after death
It is commonly claimed that nails and hair will continue growing for several days after death. This is a myth; the appearance of growth is actually caused by the retraction of skin as the surrounding tissue dehydrates, making nails and hair more prominent.
See also
References
- Template:Note American Academy of Dermatology - Nail Health
- Template:Note ImagiNail Website
- Template:Note Digi Nail Art Website
- Template:NoteTram Kim Nguyen, "The Truth About Germs", Fitness Magazine. Accessed 10 April 2005.
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