Definition
The nail (also: nail plate) is the name given to the translucent to whitish plates of the protein keratin, which are found on the fingertips as fingernails and on the tips of the toes as toenails in humans. A toenail consists of about 100 to 150 layers of superimposed corneous cells, i.e. cells that actually represent the already dead cells of the epidermis. The thickness of a nail varies greatly from person to person, ranging from about 0.05 mm for babies to 0.75 mm for some adults. In healthy people, a toenail grows an average of 0.5 to 1.2 mm per week, but with age, after injuries and in some diseases this rate can decrease.
Nail reconstruction
The structure of a nail is very complex. The area where the transition between the normal skin and the toenail is located is called the nail pocket. At the base of this nail pocket lies the so-called nail root, from which the horn plates, which ultimately represent the actual toenail, are formed.
The substance of the nail plate is provided by the so-called matrix, which is often recognizable at the origin of the nail as a bright crescent and is also known as nail moon or lunula. Under the nail plate lies the connective tissue nail bed, which is firmly fused with the periosteum of the underlying bone. At the sides, the nails are surrounded by a skin fold, which is called nail wall or nail fold.
This covers the invisible parts of the toenail and ensures that the toenail is held and protected from lateral tears, which can be very painful. The visible part of the skin, which is directly connected to the nail wall and lies on top of the nail plate, is called cuticle. The toenail itself consists in the end only of dead material, which is why it contains neither blood vessels nor nerve cells.
Therefore we have no feeling or pain in the toenail itself. The part of the skin on the fingertip or tip of the toe, however, which is at the very front and which, so to speak, pulls under the nail, is very densely covered with sensory cells. This enables the nails to fulfill their important function for the sense of touch. The function of the nails is to protect the fingertips and (especially in the case of the fingers) to support the grip, for which a distinct sense of touch is necessary.
