The fingernail, is a flat and convex plate that covers and protects the fingertips.
This plate is formed by coats of keratin, repose on the bed of skin and has two well defined borders, one stuck directly to the skin zone and the other border free, curiously, in the zone of the free border we can observe a line that marks the beginning of the free area. s
In the border that is below the cuticle we find the root of the fingernail, its birth, this zone comes from a more whitish color than the rest of the nail and we observed a zone of half moon.

At this zone the skin that coats the fingernail has two faces and is called cuticle, it has an inner face  and the other one is external and its function is to protect the root of the nail.
The fingernails are formed in the same way of the skin, his principal component is the keratin, the principal difference between the skin and the fingernail is the percentage of water, the first one contains a 85 % and the fingernail only a 12%.
 

A. Proliferating matrix
B   Ungueal  furrow
C. Dorsal face
D. Ventral face
E  Eponiquio
F. Cuticle
G. Ungueal plate
H. Plantar corneous substance
I. Ungueal bed

1.Border of the nail
2. Yellow line
3.Lateral border
4.Ungueal plate
5.Lúnula
6.Cutícula
7.Eponiquio
8.Ungueal back fold