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Nail

Nails consist of dead cells, and the visible hard part is composed of the same protein keratin, that makes up hair.

Nails form a kind of armour plating for the sensitive and vulnerable ends of the fingers and toes. They lie over the nail bed. At the bottom of the nail bed is an overlapping fold of skin topped by the cuticle. The nail bed has a very good blood supply and it is this together with the fact that the nail is thin (barely 0.5mm. thick) and transparent, which gives nails their pinkish color. At its base the nail becomes denser and the blood supply less generous, giving rise to the white half-moon technically called a lunula.

Nail Cross Section

Hidden under the fold of skin at the base of the nail is the root from which the nail grows The growth is continuous in finger nails and takes place at the rate of three to four cm. a year - considerably slower than hair which grows three or four times as rapidly. Nail growth is quickest in early adulthood and slowest in infancy and old age. The right thumbnail in right-handed people usually grows faster than the other nails and similarly the left thumbnail in left-handed people possibly because usage leads to increased blood supply. Fingernails grow more quickly than toe nails - by about four times. Nails usually grow more quickly in summer than in winter.

Nail growth also depends on nutrition and general state of health. Poor health will lead to disco1oured, dry and cracked nails. Transverse ridges in the nails will sometimes reflect a period of ill health, because will have slowed nail growth for a time.

Nails are extremely porous and can absorb 100 times as much water as an equivalent amount of skin. This cause them to swell and, although they dry out fairly efficiently and resume their normal shape, if the process is repeated too often they may spilt and become painful.