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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 skinskin,
the flexible tissue (integument) enclosing the body of vertebrate animals. In humans and other mammals, the skin operates a complex organ of numerous structures (sometimes called the integumentary system) serving vital protective and metabolic functions.
..... Click the link for more information. ). 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.
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.
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.
What does it mean when you dream about a nail?
A nail holds or binds objects together that need to be fixed or repaired. To “get nailed” is to get caught at something. Another slang expression, “hit the nail on the head,” may indicate that an accurate appraisal may repair a problem or relationship. This symbol may be seen as a fingernail or toenail. If a fingernail is pointing at something, a new direction or viewpoint is being created. If one stubs a toenail, carelessness may have caught up with the person.