ARTICLE: Anatomy Of Nail

Parts of the nail

Fingernails and toenails are made of a tough protein called keratin and have many different parts:

• Matrix - This is the only living part of the nail. It is situated behind and underneath the Nail Fold and produces protein keratin which makes up the Nail Plate. If the matrix is ever damaged in any way, it would affect the Nail Plate growth.
• Eponychium - This is the dead skin that forms around the cuticle area. This can be lifted and trimmed during a professional manicure treatment. Tends to be more prominent on males.
• Peronychium - This is the 'live' skin that folds around the cuticle area giving protection to the Matrix.
• Hyponychium - Is the area of attachment between the Nail Plate and Nail Bed that lies underneath the free edge. Anatomical terms of location Proximal and distal, end of the nail.
• Nail Plate - Is the hard and translucent portion which is composed of layers of protein keratin.
• Nail Bed - The Nail Bed is responsible for the 'pinkish' colour of the Nail Plate. It also determins what shape the nail will grow.
• Lunula - Tends to only be visible in larger nails. Is the whitish crescent shape around the base of the nail plate, is the shadow of the Matrix.
• Nail Fold - A fold of hard skin overlapping the base and sides of a fingernail or toenail
• Free Edge - The part of the nail that extends past the finger, beyond the nail plate. There should always be a free edge present to prevent infections. Ideally a free edge should be half of the 'pink' nail in length.
• Nail Groove - Acts as 'runners on drawers' and guides the direction of nail growth. They are situated down the sides of the Nail Fold.

Nails serve the same purpose as animals' hooves and horns. Along with hair and teeth they are an appendage of the skin. The only Living part of these 'appendages' are situated inside or underneath the epidermis.

Nails act as a counterforce when the end of the finger touches an object, thereby enhancing the sensitivity of the fingertip, even though there are no nerve endings in the nail itself. The growing part of the nail is the part still under the skin at the nail's proximal end. The average thickness of this portion of the nail is .016 inches, or 0.43 millimetres. In common usage, the word nail often refers to the nail plate only.

Nails grow at an average rate of 3 millimeters a month. Fingernails require 3 to 6 months to regrow completely, and toenails require 12 to 18 months. Actual growth rate is dependent upon age, gender, season, exercise level, diet, and hereditary factors. Contrary to popular belief, nails do not continue to grow after death; the skin dehydrates and tightens, making the nails (and hair) appear to grow.

This growth record can show the history of recent health and physiological imbalances, and has been used as a diagnostic tool since ancient times. Major illness will cause a deep transverse groove to form across the nails. Discoloration, thinning, thickening, brittleness, splitting, grooves, Mees' lines, small white spots, receded lunula, clubbing (convex), flatness, spooning (concave) can indicate illness in other areas of the body, nutrient deficiencies, drug reaction or poisoning, or merely local injury. Nails can also become thickened (onychogryphosis), loosened (onycholysis), infected with fungus (onychomycosis) or degenerate (onychodystrophy); for further information see nail diseases.

Wikipedia source