Nail (redirected from nails)

nail, in carpentry

nail, metal pin driven by force applied at one end into pieces of material, usually wood, to join them together. The strength of a nailed joint depends on the properties of the wood, the type and number of nails used, and the type of loads applied to the joint. When the nail is subjected to side loading, the strength of the nail itself also becomes important. Generally speaking, a nail holds better when driven across the grain of a wood than parallel with it and better in a hardwood than in a softwood. However, since a softwood has less tendency to split than a hardwood, more nails can be driven into it. Various means, such as texturing the surface of a nail or coating it with high-friction materials are used to increase its withdrawal resistance.

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nail, in anatomy

nail, in anatomy, the horny outgrowth shielding the tip of the finger and the toe in humans and most other primates. The nail consists of dead cells pushed outward by dividing cells in the root, a fold of epidermis at the base of the nail (see skin). The hard material in nail cells is the tough protein material, keratin. If the root is destroyed, the nail ceases to grow. Otherwise, growth from root to tip is achieved in about four months. The small-celled and relatively bloodless tissue near the base of the nail forms a white, crescent-shaped spot called the lunula, or moon. No pigment occurs in nail cells, but since they are translucent, their appearance is pink because of blood vessels beneath. A painful inflammation (paronychium) of the fingertip may result from infection starting in a hangnail. Pressure from improperly fitting shoes may cause the large toenail to cut into the skin along its edges (the so-called ingrown toenail). Horny derivatives of the integument, homologous to the primate nail, have evolved into various structures in other animals, e.g., the hooves of horses and cattle and the claws of birds and reptiles.

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nail

In construction and carpentry, a slender metal shaft, pointed at one end and flattened at the other end, used as a fastener. Most often used to join pieces of wood, nails are also used with plastic, drywall, masonry, and concrete. They are usually made of steel but can also be made of stainless steel, iron, copper, aluminum, or bronze. The pointed end is called the point, the shaft is called the shank, and the flattened part is called the head.

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nail

Structure made of keratin that grows on the back of the end of each finger and toe. Nails consist of a root, under the skin; a translucent plate, attached to a nail bed beneath; and a free edge. Nail plate (and probably bed) cells are produced at the root and pushed forward as new cells form behind them. They die and turn white as they reach the free edge and lose contact with the richly vascularized nail bed, which supplies them with nutrients. Fingernails grow continuously at about 0.5 mm per week; toenails grow more slowly. They protect the tips of fingers and toes and help the fingers pry, pick up small objects, and scratch.

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nail

1. a fastening device usually made from round or oval wire, having a point at one end and a head at the other

2. the horny plate covering part of the dorsal surface of the fingers or toes

3. the claw of a mammal, bird, or reptile

4. a unit of length, formerly used for measuring cloth, equal to two and a quarter inches

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nail [nāl]

(anatomy)

The horny epidermal derivative covering the dorsal aspect of the terminal phalanx of each finger and toe.

(design engineering)

A slender, usually pointed fastener with a head, designed for insertion by impact.

(engineering)

To drive nails in a manner that will position and hold two or more members, usually of wood, in a desired relationship.

(medicine)

A metallic rod with one blunt end and one sharp end, used surgically to anchor bone fragments.

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nail

Types of nails

A straight, small, rigid, slender shaft of metal, one end of which is usually pointed; the other end has a head that may be driven with a hammer; used as a fastener to join separate pieces of wood, to attach tiles to a wood sheathing on a roof, and so on. Nails were hand-wrought until the invention of machines for their manufacture in the early 19th century. See cut nail, dog nail, hand-wrought nail, wire nail, wrought nail.

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Nail 

the horny protective formation that covers the dorsal aspect of a terminal phalanx in lemuroids, simians, and man. A nail is a modified claw.

The nail, or nail plate, lies on the nail bed, which is formed from a connective tissue layer of skin. The nail bed is fused with the periosteum of the phalanx and is abundantly supplied with blood vessels and nerve endings. One differentiates the distal free end of the nail, which protrudes over the pad of the digit; the body of the nail; and the nail root, which is the proximal section of the nail. The root is bound by a fold of skin called the nail fold. At the base of the nail root is the nail groove, from which the nail constantly grows at an average rate of 3 mm per month in man.

Pathological changes and diseases of the nail are classified as onychias—diseases of the nail itself—and paronychias—diseases of the nail fold. Changes in the nail can be congenital. For example, the nail plate can be too thick or too thin, or its shape can be otherwise altered. More rarely, the nail can be incompletely developed, or the nail plate can be completely absent. The causes of acquired pathological changes include vitamin deficiency, neurotropic disorders, and skin diseases. The most common infectious diseases of the nail are fungal, for example, tinea, or ringworm.