The nail is a slightly bulging and tough keratinous coating that serves for protection. Its main function is to make a protective layer at the end of fingers and toes.
Its main constituents:
- Keratin, (A protein which has high sulphur and relatively low calcium content).
- Moisture content, (Moisture-content of the natural nail is about 18%).
- Fibres, (Its structure is made up of multiple, flattened dead cells (about 150 thin layers) which have no nuclei and are closely attached to each other, they are organized into fibres).
- Keratinous plate (Its translucency depends to what extent the keratin is translucent).
Functions: Protection the nail plate from mechanical effects, touching and holding tiny objects. The nail plate itself extends from the epidermis to the free edge, it is made up of keratin cells that are attached to the nail bed. The lower layers are softer, the upper ones are harder. The nail plate itself does not contain nerves and capillaries. It is 0,5- 0,75 mm thick, its complete growth on the hands is generally 3 months (injury, regrowth). The nail grows faster on the hand than on the foot. It is about 0,1 mm on the hand and 0,05 mm on the foot per day. The nail plate is normally smooth, shiny, tough and flexible. If it is bumpy or discoloured it may be the result of an internal organic disorder or some external effect. Injures to the nail plate remain until its full regrowth. A healthy, normal growing nail plate forms a longitudinal and transversal „C” shape (curve). Its highest point is at the midpoint over the nail bed called „apex”.
Plasticity of Nails
As the nail plate is made up of dead, necrotic cornified cells, it lacks nerve endings and can be painlessly cut, filed, formed or shaped at the free edge.
Blood Supply of Nails
Nutrients of the nail are transported by the vascular system. There is an artery on both sides of each finger that supply the lower nail groove with fresh blood. Then they flow into the dermis, the lower layer of skin, from where capillaries carry the blood forward. That is why the plate over the nail bed seems pink. Used up blood is carried back to the blood circulation by the veins.