Nails are found on the fingers and toes alike.
Formation and Orientation
Nails are made of the protein keratin, much like hair as they are related, which is tough and strong and able to protect the ends of the fingers they cover. The nail plate, nail matrix, the nail sinus and the nail bed all make up the nail.
The matrix is broken up into two sections; the nonvisible layer is simply referred to as the matrix while the visible part is called the lunula. The matrix is the tissue protected by the nail and holds lymph and blood cells as well as many nerves. This part of the nail produces the cells for the nail plate. The matrix lasts as long as the human body provides the nutrients necessary to produce the cells and keep the nerves healthy and functioning. The lunula is the whitish part on the lower base of the nail that appears crescent-shaped. The nail sinus stems from the matrix as it is the place where the nail root is located.
The nail bed is located beneath the actual nail plate. The dermis and epidermis that make up the nail bed are attached by matrix crests which are small longitudinal grooves. These grooves become more prominent over time when the nail becomes thinner because the production of the cells that form the nail plate is slowing.
The nail plate is the hard, protective part of the nail that is formed by keratin and the dead cells that have been provided by the matrix. The distal edge (free margin) is the that is next to the cutting edge of the nail. The hyponychium (quick) protects the nail bed as it is located beneath the plate and the fingertip’s skin, while the onychodermal band is the actual seal between the two.
The eponychium is sometimes mistakenly called the cuticle that connects the nail base to the skin at the left and right edges of skin surrounding the nail. The cuticle is made up of dead cells, much like the nail plate, that are pushed out and extend as more cells die while the eponychium is the living cells that will turn into the cuticle. The perionyx is the part of the nail that connects the eponychium to the lunula.
On average, nails can grow at a rate of 3 mm per month. This is a loose estimate as age, sex, season, diet, hereditary and exercise all play a large factor in growth.
Nails function as to protect the fingertip or toe and their surrounding tissues. Nails can also make it easier and can enhance the sense of touch.
The nail can allow for more pressure to be applied more. There are many nerve endings which allow the brain to interpret many different types of information that we receive when utilizing touch.
Image Caption: Basic nail anatomy. Credit: Kipton/Wikipedia