The structure of the nail

The nail matrix

This is the only living reproducing portion of the nail. Here is determined the quality, the health and strength of the nails, that weeks or months later is visible ready to be filed and glamorised and protected with nail enamel.

It is here at the matrix the at all new cells form within the germinative layer of the skin, through the process mitosis. They are continually pushing the old cells forward towards the fingertip to form the nail plate.

About one fifth of the entire length of the nail is hidden beneath the skin; this is the vital matrix, which plays such an important part in the formation of the fingernails. As long as the matrix is not injured, then any damage to the nail plate is usually only temporary .The matrix contains nerves, lymph and blood vessels and the nail root originates form the matrix area.

The nail bed

The nail bed is a continuation of the matrix and is similar in many ways to ordinary skin. It supports the nail plate and on its surface presents numerous parallel ridges, which ’dovetail’ exactly with similar ridges on the underside of the nail plate, welding them firmly together. These two structures nail plate and bed move forward together. A sharp blow may cause minute haemorrhages in the nail bed, beneath the nail plate appearing as tiny ‘blue spots ‘, which are tiny bruises. These will move forward to grow out of the nail plate.

The nail bed is supplied with many blood vessels, which provide the nourishment necessary for the continued growth of the nail, along with an abundant supply of nerves.

The Lunula (half moon)

This is located at the base of the nail plate and is the pearly crescent shaped section of the nail plate. It is the only visible portion of the matrix. and appears pale due to a reduced blood supply It is some times referred to as the bridge between the living matrix and the horny nail plate, as the Lunula forms part of the upper matrix, it is part of the growing area and the nail plate and nail bed are formed here.

The nail plate

It consists of compressed dead keratinised cells. These cells lie in three layers held together with a minimum of moisture and fat, which tends to decrease with age, just as the skin does. A special cement like substance which the cells secrete themselves binds them together to form a hardened translucent surface which we call the nail plate this outer layer is harder than the inner layer.

The normal water content of the nails is around 12to 18% this is necessary to keep the nails in good pliable condition, too little the nails flake.

The nails contain a very low percentage of fat 0.15 to 0.75% by weight between the keratinised cells hence the fact that the nails are ten times more permeable to water than the skin.

The free edge

Is the portion of the nail plate, which extends beyond the fingertip? Its function is to protect the fingertips from physical harm. Formed from 3 layers of cells cemented together for strength, however due to lifestyle these 3 layers sometimes separate, and cause flaking of the nail plate.

The nail wall

Are the folds of skin, which overlap the sides of the nail; it forms the frame to the nail and provides protection from physical harm.

The nail groove

As the nail grows forward it moves along the nail grooves at the side of the nail which hold the nail in place, keeping it parallel and protected by the folds of the nail walls on either side of the nail plate.

The mantle

Is the deep fold of skin in which the nail root is embedded.

The Hyponychium (HI-PO-NIK-E-UM)  

Is a layer of the epidermis located under the free edge of the nail plate, upon which the nail body rests.

The Eponychium (Ep-o-nik-eum)

Is an extension of the cuticle at the base of the nail body, which partly overlaps the Lunula, and moves forward with the nail plate as it grows. Its function is protection of the growing area of the nail.

The Perionychium (Per-I-o-nik-e-um)

Is the portion of the cuticle surrounding the entire nail border.

Blood supply

The blood supply to the fingers is carried by the digital arteries which are rich in nutrients and oxygen and feed the matrix cells, nail bed and surrounding structures which enables cell production to occur and results in the formation of the nail plate.

Cells

The cells which form the nail plate arise form the basal cell layer of the epidermis where they multiply, here the cells are soft a with a nuclei as the cells grow older they harden and die undergoing keratinisation the cells secrete a cement like material that binds them together to form a strong nail plate composed of 3 layers.

Protein

Keratin is the epidermal protein found in both the skin, hair and nail plate. It comes in two forms of and hard keratin. Within the nails it is termed as onychin keratin to differentiate it from other forms of keratin. It is a stronger and harder form of keratin with high sulphur content of 4 to 8 % with low moisture and fat content. Keratin forms in continuous sheets to make-up the structure of the fingernails. Keratin as a protein contains the following elements:

• Carbon
• Hydrogen
• Nitrogen
• Oxygen
• Sulphurs

Click here for a powerpoint presentation on the Nail anatomy