Nail (anatomy)

As Nagel (Latin unguis ) is in primates a domed, translucent Keratinplatte on top of the finger or toe refers, on the one hand, on the other hand is used to support the grasping function of the protection of the fingertips.

The equivalent to the nail in the animal world are called claws, hooves or claws. The adjective means periungual around in the vicinity of a finger or toe nail or around the nail and subungual means under the nail, ie in the area of the nail bed or below.

Description and function

The nails (also called nail plates ) are derivatives of the epidermis, which occur only in primates in the form illustrated here. They form at the nail root of horn plates. The nail root is located at the base of the nail pocket. The epithelium, which rests in the nail pocket posterior to the nail plate, is referred to as eponychium; that which the nail rests dorsally ago when hyponychium. Under the hyponychium is the nail bed ( connective tissue ), which is firmly adherent to the periosteum of the distal phalanx. In the area of ​​the nail root hyponychium is the matrix, it forms the substance of the nail plate - the corresponding area is also known as nail moon ( lunula ) recognizable. Laterally, the nails are surrounded by a fold of skin, called the " Paronychia ". As Perionychium or Perionyx ( German cuticle ) is called the nail wall on the dorsal nail plate lies directly visible skin share.

Considered mechanically put the nails an abutment for the sensitive finger pads ( the animal " Tastballen " ); they are the nail bed ( matrix or Matrixepithel ) and are sufficiently firmly connected with this to be an effective scratch, scratch and Zupfwerkzeug be able to. How important is the nail for these functions (3-4 mm) of the epidermis is also evident in the dense sensitive innervation mainly in the front area. Where the fingertip skin is sufficient under the nail, the nail plate is almost immobile their tactile information elicited by a Sinneszellensaum who understandably more sensitive than the rest of the finger. Just by touching an object with the nail surface finish and hardness can be determined, which would otherwise not be possible. The area of ​​the Hyponychiums is almost deaf, but here is a contact without existing nail painful.

Are fingernails strongly arched upward, while a total of more round than oblong, one speaks of " watch glass nails ".

Nail formation and growth

Nails are made of 100 to 150 irregularly superimposed layers of horny cells and are usually between 0.05 ( nail of a baby ) and 0.75 mm thick. The nail Education ( Onychisation ) is a keratinization deep behind the nail fold without formation of the intermediate keratohyalin. The various nails grow at different rates, about 0.5-1.2 mm per week. A delay of nail growth occurs in old age, on at trauma and certain pathological processes.

Nail fold

The nail fold ( paronychia Syn ) is the portion of the skin, including the finger and toe nails on the side and at the root. This skin survey covers the non-visible part of the nail and gives this grip. The nail wall also serves as a protection against painful tears.

Diseases and injuries

As a rule of thumb applies: Where a fault, the nail matrix, the Nagelläsion grows out. Subject to the nail bed, it is a location- resistant lesion. Fingernails and toenails may be affected by a number of diseases. One of the most frequently and with almost described only by women problems concerns too soft and brittle nails: The reasons for this symptom are not known to be more scientifically researched. However, to assume that by chemical nail polish remover the brittleness is favored or caused. Even an inherited predisposition may be responsible for the brittleness.

Brittle and splintering nails can be a sign of a lack of biotin (vitamin H). Biotin is essential for the formation of the horny substance keratin, thus contributing significantly to the healthy growth of skin, hair and nails with.

Through skin or nail injuries (among others) can cause an infestation by nail fungus ( onychomycosis ), which color and shape of the nails are affected. A treatment as the only slow-growing toenails is lengthy. Many systemic diseases also leave signs on the nails, such as psoriasis (psoriasis). She leaves behind a characteristic changes pitted and oil stains, and in extreme cases crumbs nails as a sign of a complete nail dystrophy.

Longitudinal grooves on the nails are usually a normal aging phenomenon which occur no later than 35 years. Transverse grooves usually develop in a slowdown in growth during illness (eg, infection with high fever ).

Injuries to the nail bed, for example, jammed in a door, or the like, usually last a lifetime visible. Damage caused by excessive use or strain to grow ( for example, by long- distance running ), if enough time is given to back out. When not enough time for healing the nail root is permanently damaged beyond repair and the nail falls off.

White spots

The white spots on the nail there is a lack of fusion of the nail plates that appear milky white due to the altered light reflection (similar to the lunula ). The intact nail surface reflects, however, by its nearly smooth structure, the light collimated, so that the nails slightly affect specular. The lack of fusion has many different causes, for example, it is caused by a bump or also by disease or drugs. The widespread rumor, white patches or spots on fingernails ( Leukonychia punctata) are signs of protein deficiency or due to a calcium or magnesium deficiency, is wrong.

Hangnail

A hangnail (after Dutch nijdnagel " nail envy ."; According to the popular belief, a hangnail would result if you get hit by a jealous look) is a detached, but still stuck small strip of skin on the side of the nails. This can be painful tearing and occasionally also cause inflammation. To prevent this, you should cut off the hangnail as close to the approach.

Nail-biting

A common human expression of nervousness is the chew off the protruding parts of the nails and the cuticles ( eponychium ), see onychophagia.

Fingernail test

In the rescue medicine the fingernail test is a method of orienting determination of peripheral blood circulation situation, which allows a rough conclusion on the circulatory situation, especially in little time for the investigation of any injuries, such as disasters and accidents. Here, the nail is pressed briefly into the nail bed, so that this colored white. If the time is up for re- coloring more than one second, there is a lack of blood supply. However, previous nail injuries can distort this result.

As a fingernail sample and material tests are referred to. Either the nail is pressed into the material and then paid to deformation or the like, or the examiner moves with the nail over the surface to determine the surface roughness on the basis of a reference standard.

The fingernail test is not to be confused with the proverbial nail sample.

Care

The care of the fingernails and toenails is called manicure or pedicure. Regular cleaning, cutting and filing the nails with appropriate tools prevents diseases. However, care should be taken while filing the nails that always polishes in one direction to prevent fraying of the nail. Commercially various nail care products are available.

Society and Culture

Through long fingernails showed in China in the Qing Dynasty, the carrier that he had to engage in any physical work. This is still today in some countries of Asia and Africa (Egypt) common, where usually only the nail of the little finger is left uncut.

In German, is the phrase " Burn on the nails " that something is very urgent for someone. You possibly comes from the fact that the monks at night praying or reading texts, a small candle on a thumbnail attached and came towards the end of the reading out of time, because it burned on the nails.