The Structure Of The Nail Guide And Information
The technical term for a nail is onyx and it consists of three main parts:-
- The nail root or matrix
- The nail plate
- The free edge
Like hair, nails are appendages of the skin – translucent structures that protect the tips of the fingers and toes and facilitate the picking up of small objects. They are a modification of the epidermis and are composed of a hard fibrous protein called keratin. The chemical composition of keratin is:-
Keritinisation is the change of living cells containing a nucleus into flat, dead, horny cells with no nucleus. The process starts in the basal layer of the epidermis and ends in the horny layer. The nail plate lies on the nail bed (the dermis) which contains nerves and blood vessels. It is made up of cells which are pushed forwards from the matrix and they go through a process of keratinisation causing the nail plate to grow in thickness and length. New cells are formed in the matrix. These cells divide to produce new cells in the matrix. Partly keratinised cells which are losing fluid and contain a nucleus which is beginning to disintegrate form the nail in the area of the lunula. Dead horny keratinised cells make up the nail plate.
The general health of the body is reflected in the condition of the nails. A healthy nail is pink in colour with a smooth, slightly curved surface and clear of any marks or defects. A new nail will always grow in place of an injured or lost nail, unless the matrix is damaged in which case a deformed nail may grow in its place.
Structure Of The Nail Diagram
Breakdown Of The Structure Of The Nail
The Matrix is situated immediately below the cuticle and is the only living reproducing part of the nail. It contains nerves and blood vessels and cell production occurs here. When the new cells are formed they are continually pushing forward to form the nail plate. A healthy matrix will produce a healthy nail but if injury occurs in this area the nail may grow with a deformity that may be temporary or permanent. The cells receive their nourishment from the blood supply. Function: to produce cells which finally form a new nail.
The Lunula (also known as the ‘half moon’) is the point where the matrix and the nail bed meet. It is crescent shaped and pearly in colour because the cells are pushed so closely together that the blood capillaries in the nail bed, which provide the pink glow, cannot be seen. Function: the intermediate stage between the living matrix and the dead cells of the nail plate.
The Nail Bed is a continuation of the matrix and is abundantly supplied with nerves and blood vessels. It is the part of the finger upon which the nail plate rests. It has numerous parallel ridges that dovetail exactly with ridges on the under-surface of the nail plate. Function: supplies nourishment via its blood supply to the matrix for healthy nail growth and provides support for the nail body.
The Nail Plate is composed of dead compressed skeleton cells and contains no blood vessels or nerves. The compressed cells form three layers: Nail Body – the visible portion of the nail plate which rests on and is attached to the nail bed and extends from the nail root to the free edge; Nail Root – originating from the matrix, it is situated at the base of the nail plate beneath the mantle where one fifth of the entire nail plate is hidden; Free Edge – the part of the nail plate which extends beyond the fingertip and is the most vulnerable part of the nail, easily damaged by knocks etc., it is pale in colour due to it not being attached to the nail bed and is the part which is shaped during a manicure. Function: protects the ends of the fingertips and toes, particularly the numerous nerve endings found in these areas.
The Mantle is the deep fold of skin over the matrix and around the base of the nail plate. Function: to provide a thick and protective skin covering to the matrix and base of the nail.
The Cuticle is the narrow border which surrounds the nail and can be divided into three parts: Eponychium – the portion of the cuticle at the base of the nail plate which slightly extends on to the lunula and may be removed during a manicure; Perionychium – the portion of the cuticle that surrounds the sides of the nail; Hyphonichium – the portion of the cuticle on which the nail plate rests underneath the free edge, at the point of separation between the nail plate and nail bed, where the nail plate becomes the free edge, indicated by the dividing flesh line. Function: the cuticle forms a vital barrier against infection protecting the matrix and the underlying tissues of the nail root. It also helps to form a framework for the nail.
Nail Walls are the folds of the skin overlapping the sides of the nails. Function: together with the cuticle it provides a framework for the nail and protects the outer edges of the nail plate against injury and infection, allowing it to grow along the nail bed without damage.
Nail Grooves are the grooves or furrows at the sides of the nail upon which the nail moves and acts as a guideline for the nail to follow. Function – keep the nail plate in the correct position as it grows and determines the shape of the nail. If damaged the nail will grow distorted.
Cells – nail growth takes place by cell division (mitosis) in the matrix. Older cells are pushed forward as new ones are produced and gradually they harden and die. The cells are moved away from their blood and nerve supply, their nuclei are destroyed and keratinisation takes place. This is the reason why it does not hurt when the nails are cut or filed. The nail bed is thought to be involved in the formation of the nail plate. New cells produced in the germinating layer of the nail bed are pushed forwards by the movement of the upper nail plate and become attached to it, so forming the lower part of the plate. The nail plate moves forward with the nail bed.
Protein-Keratin – like hair, nails are appendages of the skin. They are composed of a hard fibrous protein called keratin. The chemical composition of keratin is: Carbon 51%, Hydrogen 7%, Oxygen 22%, Nitrogen 17%,Sulphur 3%. The blood supply circulates in minute capillaries to bring about nail and hair growth and is rich in amino acids that help to form protein-keratin. Keratinisation is the change of living cells containing a nucleus into flat, dead, horny cells with no nucleus. The process starts in the basal layer of the epidermis and ends in the horny layer. As the cells are pushed from the matrix they go through a process of keratinisation, causing the nail plate to grow in thickness and length. Partly keratinised cells that are losing fluid and contain a nucleus that is beginning to disintegrate form the nail in the area of the lunula. Dead horny keratinised cells make up the nail plate.
Moisture/Fat – the water content of the nail affects its pliability or brittleness. The normal water content is approximately 10-12% for nails in a good pliable condition but at a lower percentage the nails becomes brittle and tend to split or flake. Nails also contain a very low percentage of fat, normally only 1%. The compressed cells of the nail plate are held together by a minimum amount of moisture and fat, which decrease with age, producing a dryer nail condition.
Blood Supply – the blood carries out the functions of supplying nourishment and oxygen to bodily tissues and organs, and removes their waste products. The heart and blood vessels are the mechanism by which a constant circulation of the blood throughout the body is maintained. Blood is pumped by the heart along arteries (which carry oxygenated blood from the heart to all parts of the body), and veins (which carry deoxygenated blood from all parts of the body back to the heart). Blood supply to the nails starts from the subclavian artery in the neck, which passes through the axilla, becoming the axillary artery, then becomes the brachial artery as it reaches the upper arm. The brachial artery descends down the front of the arm and gives off branches to the muscles, bones and skin. Below the elbow it divides into two branches – ulnar artery and radial artery. In the palm of the hand, both these arteries are joined to form two arches – the superficial palmer arch and the deep palmer arch, from which spring smaller arteries that supply the fingers and palm – the metacarpal arteries and digital arteries. The veins form a dense network in the hand and forearm – the cephalic vein and the basilic vein being the main ones that emerge at the elbow. The cephalic vein runs up to the shoulder, under the clavicle and joins the subclavian vein. The basilic vein runs alongside the brachial artery to the axilla where it continues as the axillary vein, and ultimately as the subclavian vein in the neck.
Understanding the structure of the nail is essential in understanding how to strengthen nails, we hope that you have found this page beneficial