Nail Biology
For some people, nails are the highlight of the hand. Beautiful, well groomed nails enhance your overall appearance. Nails shield the ends of the fingers and toes from trauma and serve to protect the delicate sense of touch in the fingertips.
Nails are vestigial remnants of defensive weapons of our distant ancestors. In humans, nails evolved as aids for picking up small objects and for scratching. Our nails, like hair, are made of the hard protein called keratin. Also like hair, the nail is a direct outgrowth of the skin. The primary protein in nails is keratin, the same hard tough protein that also forms the feathers and beaks of birds, the claws of animals. Keratin is tough and resists most environmental stresses, but like hair is damaged by alkaline conditions and excessive heat.
Nail Structure
The structure of the nail and its growth is very similar to hair. The nail is formed in a pocket of skin called the nail fold which has grown inward (somewhat like a hair follicle).
Nail Plate - The nail plate is the scientific name of what we commonly call our nail. It is hard, smooth, shiny, somewhat rectangular, and slightly convex. The plate is translucent and essentially colorless, but appears pink because of the network of blood vessels under the nail bed below the nail plate. The nail plate grows as if in a 3-sided tunnel with no roof.
The Nail Plate consists of three layers.
The Dorsal Layer is the topmost layer (outer) of the plate. Its cells are primarily soft keratin and they are less flattened than nail cells of the intermediate layer below it.
The Intermediate Layer is the middle layer of the nail plate and its cells are primarily hard keratin and are flatter, larger, and more compact than nail cells above and below it.
The Ventral Layer is the bottom layer of the nail plate. Its cells are primarily made of soft keratin and similar to the topmost or ventral layer. Its thickness is similar to the dorsal layer.
The nail cells forming the nail plate are bound to each other by numerous tiny protein fibers. After nail cells are formed at the matrix they progressively broaden and flatten as they move to the fingertip.
The Hyponychium is the portion of the fingertip underneath the outer free edge of the fingernail. The outer (top) layer of the skin is attached to the under side of the nail plate and gives the characteristic whitish color to the nail’s free edge.
The Lunula is the whitish, half-moon shaped area visible at the base of the nail. It is at the junction between the nail matrix and the nail bed. The white half-moon is due to nail cells of the lunula area that are not fully mature, keratinized, and differentiated. The size and shape of the lunula is very individual and varies in each finger of every individual. In some people it is well marked while in other persons it is undefined or hazy. The lunula tends to disappear in as we get older.
The Cuticle is an extension of the skin of the roof of the nail bed (eponychium). The upper ridge of the nail bed is under the cuticle which itself is an extension of the skin of the finger.
The Nail Matrix is the area which generates the nail and is also called the root of the nail. It appears wedge shaped with the nail plate fixed at the opening. The outer layer of the matrix is specialized cells that create the keratin that grows out as the nail plate.
The Nail Bed is the finger tissue that supports the nail. The nail bed does not contribute to the growth of the nail but the surface of the nail bed has vertical ridges and depressions that interlock into the nail plate to give a firm adhesion between the nail bed and the nail plate. The nail bed grows out along with the nail plate and its elaborate network of blood capillaries help provide nutrition for the nail plate. When the nail plate is separated from the nail bed such as after an injury, the nail plate becomes discolored, cloudy and distorted.
Nail Growth
While the nail is similar to hair, it does not undergo the hair cycle of growth and non-growth. Nails grow continuously throughout your life. They grow approximately one-half to one millimeter weekly. Complete nail growth for the nail plate to completely replace itself from the time it is formed in at the root until it reaches beyond the finger tip takes from 5 to 7 months. Toenails grow much more slowly, about third to half the growth rate of fingernails. Nails grow more during the summer. The middle finger nail grows fastest, with the growth rate progressively decreasing on the fourth, second, fifth fingers and finally the thumb. When a nail is injured and falls off, it is replaced at the normal growth rate. However, if the nail matrix is destroyed, the new nail will not grow. If the matrix is damaged, the new nail is likely to grow in a distorted form. Right-handed people’s nails grow more quickly on the right hand and left- handed peoples nails growth faster on left-hand
Protecting Nails
Like hair, nails are usually healthiest in their natural state, and while nail polishes and cosmetic nails may improve your appearance, they tend to degrade nail health.
Nail health is best if you avoiding repeated wetting and drying of the nails. Exposure to water, drying and stresses of daily wear and tear cause nails to become more brittle, and more prone to chipping, splitting and breaking. The keratin protein in nails is hardest at a slightly acid pH and many alkaline detergents, soaps and cleaners cause a loosening of the fibers of keratin proteins that form the nail.
In recent years, salons say that more nail damage is caused by cosmetic/beautifying procedures. However, nail protection is still equally important.
Cosmetics such as nail polishes and artificial nails generally degrade nail health. Give your nails a break from cosmetic polishes and artificial nails for one to three months per year to allow the nails to recover their health. Treatments such as nail strengtheners and hardeners can help to protect nails from breakage, but polish removers weaken nails. When applying coating of nail strengtheners and hardeners, apply them a subsequent coats over the previous treatments rather than removing the earlier coating.
Cotton lined rubber gloves are best for nails and should be used when during household or job-related work that involves getting the hands wet.
). I put little to no effort into growing or protecting my nails; they were strong and would not break easily. However, this did not translate to my hair. It was the exact opposite experience. Short, breaking, seemingly ungrowing and dry dry hair.
