question: What happens to the tiny bits of minerals, like sand, when they enter deep into your fingernails?
comment: So under the bottom of your nails, near the cuticle, is a patch of skin called the nail bed. This is constantly making new skin, and new nail. The skin and the nail grow forwards together. When they separate at the end, the skin cells die off, and fall off as dead skin flakes. If you get stuff stuck deep in under your nails, it will get carried out by this process.
passages: Onycholysis
  
  Onycholysis is a common medical condition characterized by the painless detachment of the nail from the nail bed, usually starting at the tip and/or sides. On the hands, it occurs particularly on the ring finger but can occur on any of the fingernails. It may also happen to toenails. 
  
  Onycholysis can occur in many conditions, including psoriasis. In thyrotoxicosis, it is thought to be due to sympathetic overactivity. It may also be seen in infections or trauma.
  
  Section::::Causes.
  
  BULLET::::- Unknown
  
  BULLET::::- Trauma, excessive manicuring
  
  BULLET::::- Infection: especially fungal
  
  BULLET::::- Skin disease: psoriasis, dermatitis
   Nails can also become thickened (onychogryphosis), loosened (onycholysis), infected with fungus (onychomycosis), or degenerate (onychodystrophy). A common nail disorder is an ingrowing toenail (onychocryptosis).
  
  DNA profiling is a technique employed by forensic scientists on hair, fingernails, toenails, etc.
  
  Section::::Clinical significance.:Health and care.
  
  The best way to care for nails is to trim them regularly. Filing is also recommended, as to keep nails from becoming too rough and to remove any small bumps or ridges that may cause the nail to get tangled up in materials such as cloth.
   Section::::Nail dust generation.
  
  Healthcare providers may use podiatry drills on onychauxic (thickened) nails of patients to alleviate or eliminate pain, prevent or treat subungual ulcerations, allow better penetration of topical antifungal agents, or improve cosmesis, all in effort to improve the patient’s “quality of life.” In a study conducted by Miller, 65% of respondents reported routinely drilling thickened toenails. However, the improved effectiveness of antifungal drugs such as itraconazole and terbinafine reduces the need to drill these infected nails. 
   BULLET::::- "Onycholysis" is a loosening of the exposed portion of the nail from the nail bed, usually beginning at the free edge and continuing to the lunula. It is frequently associated with an internal disorder, trauma, infection, nail fungi, allergy to nail enhancement products, or side effects of drugs.
   Insufficient vitamin B12 can lead to excessive dryness, darkened nails, and rounded or curved nail ends. Insufficient intake of both vitamin A and B results in fragile nails with horizontal and vertical ridges. Some over-the-counter vitamin supplements such as certain multivitamins and biotin may help in growth of strong nails, although this is quite subjective.
   Psoriatic nails are characterized by a translucent discolouration in the nail bed that resembles a drop of oil beneath the nail plate. Early signs that may accompany the "oil drop" include thickening of the lateral edges of the nail bed with or without resultant flattening or concavity of the nail; separation of the nail from the underlying nail bed, often in thin streaks from the tip-edge to the cuticle; sharp peaked "roof-ridge" raised lines from cuticle to tip; or separation of superficial layers of the nail followed by loss of patches of these superficial layers, leaving thin red nails beneath; or nail pitting–punctate changes along the nail plate surface.
   Psoriasis can affect the nails and produces a variety of changes in the appearance of finger and toe nails. Nail psoriasis occurs in 40–45% of people with psoriasis affecting the skin and has a lifetime incidence of 80–90% in those with psoriatic arthritis. These changes include pitting of the nails (pinhead-sized depressions in the nail is seen in 70% with nail psoriasis), whitening of the nail, small areas of bleeding from capillaries under the nail, yellow-reddish discoloration of the nails known as the oil drop or salmon spot, dryness, thickening of the skin under the nail (subungual hyperkeratosis), loosening and separation of the nail (onycholysis), and crumbling of the nail.
   Inherited accessory nail of the fifth toe occurs where the toenail of the smallest toe is separated, forming a smaller "sixth toenail" in the outer corner of the nail. Like any other nail, it can be cut using a nail clipper.
  
  Section::::Clinical significance.:Effect of nutrition.
  
  Vitamin A is an essential micro-nutrient for vision, reproduction, cell and tissue differentiation, and immune function. Vitamin D and calcium work together in cases of maintaining homeostasis, creating muscle contraction, transmission of nerve pulses, blood clotting, and membrane structure. A lack of vitamin A, vitamin D, or calcium can cause dryness and brittleness.
   BULLET::::- "Chronic paronychia" is an infection of the folds of tissue surrounding the nail of a finger or, less commonly, a toe, lasting more than six weeks. It is a nail disease prevalent in individuals whose hands or feet are subject to moist local environments, and is often due to contact dermatitis. In chronic paronychia, the cuticle separates from the nail plate, leaving the region between the proximal nail fold and the nail plate vulnerable to infection. It can be the result of dish washing, finger sucking, aggressively trimming the cuticles, or frequent contact with chemicals (mild alkalis, acids, etc.).
   The nail can be smoothed and shaped accurately by taking light, even strokes in one direction across the top of the nail. Twenty to thirty easy strokes can typically shorten excessively long fingernails, while five to ten strokes are sufficient for shaping the nails.
  
  Guitar players have also been known to use emery boards to smooth out calluses which may snag the strings of their guitars.
  
  Section::::Materials.:Emery board.:Emery pitches.
   BULLET::::- "Acute paronychia" is an infection of the folds of tissue surrounding the nail of a finger or, less commonly, a toe, lasting less than six weeks. The infection generally starts in the paronychium at the side of the nail, with local redness, swelling, and pain. Acute paronychia is usually caused by direct or indirect trauma to the cuticle or nail fold, and may be from relatively minor events, such as dishwashing, an injury from a splinter or thorn, nail biting, biting or picking at a hangnail, finger sucking, an ingrown nail, or manicure procedures.
   Section::::Causes.
  
  The causes of nail psoriasis are unknown. It has been suggested that fungi may play a role.
  
  Section::::Diagnosis.
   BULLET::::- "Onychodystrophy" is a deformation of the nails that can result from cancer chemotherapy which includes bleomycin, hydroxyurea, or 5-fluorouracil. It can include discoloration of the nail, or dyschromia.
   BULLET::::- "Onychomadesis" is the separation and falling off of a nail from the nail bed. Common causes include localized infection, minor injury to the matrix bed, or severe systemic illness. It is sometimes a side effect of chemotherapy or x-ray treatments for cancer. A new nail plate will form once the cause of the disease is removed.
   Human nails grow at a rate which varies with many factors: age, and the finger or toe in question as well as nutrition. However, typically in healthy populations fingernails grow at about 0.1mm/day and toenails at about 0.05mm/day. With this in mind the date of the stress causing Beau's lines and other identifiable marks on nails can be estimated. As the nail grows out, the ridge visibly moves upwards toward the nail edge. When the ridge reaches the tip of the digit involved, the nail edge recedes and the fingertip can become quite sore due to the mis-shapen nail pressing into the flesh deeper than usual, and exposing the sensitive nail bed (the quick) at the nail edge where the nail has receded back.
   Section::::Health implications.
  
  Fungi are ubiquitous organisms that play a vital role in decomposing organic matter. Many species of fungi live on the human body and some will infect nails causing a condition called onychomycosis. There are oral and topical antifungal therapies for this condition, however, in some instances cutting, filing, or abrading the nail may be necessary to improve cure rates. Thickened nails caused by injury, infection, diabetes, psoriasis, or vascular disease may require the use of a mechanical therapy, which can expose the healthcare worker to microbial dust. 
   The longest female nails known ever to have existed measured a total of 601.9 cm, an average of 60.19 cm (23.7 inches) for each fingernail. Contrary to popular belief, nails do not continue to grow after death; the skin dehydrates and tightens, making the nails (and hair) appear to grow.
  
  Section::::Function.:Permeability.
   Onychogryphosis
  
  Onychogryphosis is a hypertrophy that may produce nails resembling claws or a ram's horn.
  
  Section::::Causes.
  
  Onychogryphosis may be caused by trauma or peripheral vascular disease, but most often secondary to self-neglect and failure to cut the nails for extended periods of time. This condition is most commonly seen in the elderly.
  
  Section::::Treatment.
  
  Some recommend avulsion of the nail plate with surgical destruction of the nail matrix with phenol or the carbon dioxide laser, if the blood supply is adequate.
  
  Section::::Epidemiology.
   Risk factors include repeatedly washing hands and trauma to the cuticle such as may occur from repated nail biting. In the context of bartending, it is known as "bar rot".
  
  Prosector's paronychia is a primary inoculation of tuberculosis of the skin and nails, named after its association with prosectors, who prepare specimens for dissection. Paronychia around the entire nail is sometimes referred to as "runaround paronychia".
   Section::::Treatment.
  
  It is primarily the farrier who takes care of nail prick and close nails.
  
  If the nail prick is discovered at once further treatment is usually not necessary. Sometimes the whole shoe is taken off. If there is suspicion of dirt or bacteria having entered the wound together with the nail the nailhole should be enlarged to obtain drainage and the nail hole can be irrigated with dimethyl sulfoxide, povidone-iodine solution, or hydrogen peroxide.
   As far as the working mechanism of a rock nail is concerned, the strains of the rock induce a stress state in the nail composed of shear and traction stress, due to the roughness of the joints, to their opening and to the direction of the nail, generally non-orthogonal to the joint itself. The execution phases of setting up the nail provides for:
  
  BULLET::::- formation of any header niche and perforation
  
  BULLET::::- setting up of a reinforcement bar (e.g. a 4–6 m long FeB44k bar)
  
  BULLET::::- concrete injection of the bar
   BULLET::::- "Erythronychia", red bands in the nail from some inflammatory conditions.
  
  BULLET::::- "Melanonychia", a black or brown discoloration of the nail, with numerous causes.
  
  Section::::Nail changes and conditions associated with them.
  
  Nail inspection can give hints to the internal condition of the body as well. 
  
  Nail disease can be very subtle and should be evaluated by a dermatologist with a focus in this particular area of medicine. A nail technician may be the first to note a subtle change in nail health.
  
  Section::::Nail changes and conditions associated with them.:Pliability.
   Bluish or purple fingernail beds may be a symptom of peripheral cyanosis, which indicates oxygen deprivation.
  
  Nails can dry out, just like skin. They can also peel, break, and be infected. Toe infections, for instance, can be caused or exacerbated by dirty socks, specific types of aggressive exercise (long-distance running), tight footwear, and walking unprotected in an unclean environment. Common organisms causing nail infections include yeasts and molds (particularly dermatophytes).
   Nail file
  
  A nail file is a tool used to gently grind down and shape the edges of nails. They are often used in manicures and pedicures after the nail has been trimmed using appropriate nail clippers. Nail files may either be emery boards, ceramic, glass, crystal, plain metal files or metal files coated with corundum.
  
  A nail drill is a powered rotary tool, which is used by a nail technician to file nails.
  
  Section::::Materials.
  
  Section::::Materials.:Emery board.
   BULLET::::- "Koilonychia" is when the nail curves upwards (becomes spoon-shaped) due to an iron deficiency. The normal process of change is: brittle nails, straight nails, spoon-shaped nails.
  