| Eponychium is the visible part of the proximal nail fold that
appears to end at the base of the nail.
Cuticle: The eponychium will shed a thin, colorless layer
of skin that rides on the nail plate and appears to grow from under the
proximal nail fold. It is this transparent skin, which is called the
'true cuticle', that is removed during
the manicuring process.
Lunula: The opaque pale white 'half moon' at the base of the
nail, and forms the emerging immature, plump nail plate cells. As these
cells grow forward, they lose their inner material and become flat, hard
and transparent.
Distal Edge: The distal edge is commonly referred to as the 'free edge'. Nail Plate:
The nail plate is made of keratin protein formed by amino
acids. These proteins are a strong, flexible material made from
many layers of dead, flattened cells. Hair and skin are also
keratin protein; however, they are much softer and more flexible.
Matrix: The matrix produces the cells that become the nail
plate. The size, length and shape of the matrix determine width
and thickness of the nail plate. It is the shape of the fingertip
bone that determines if the nail plate is flat, ski-jump, arched or
hooked.
Nail Bed: The nail bed is made of two types of
tissue: dermis and epidermis. The dermis is the lower
portion which is attached to the bone, while the epidermis lies just
underneath the nail plate. The epidermis moves forward with the
nail plate and is attached to the dermis by tiny 'rails and grooves'
that allow the nail plate to move -- much like a train rides on its
tracks. As we age, the nail plate becomes thinner and we see
evidence of the 'rail and groove' as vertical ridges in the nail plate.
Solehorn: This type of cuticle is a layer of
translucent, dead tissue that is shed from the seal between the nail
plate and the hyponychium. It either sloughs off on its own, or is
removed during the manicure process. This skin, if not properly removed, can become stained
with nicotine and/or other chemicals and will give the appearance that the
distal edge of the nail plate is discolored.
Hyponychium: Refers to the soft skin that is the distal end of the
nail unit and the nail bed. It lies directly under the 'free
edge'.
Onychodermal Band: This is the seal between the nail
plate and the hyponychium. It is found just under the free edge
and can be recognized by its glassy, grayish color.
| Cutaway
of the Finger |
The Onychodermal Band
is found in that portion of the nail where the nail bed
ends. It cannot be seen on some individuals while it
is highly prominent on others.
|
The shape of the nail
plate is determined by the shape of the finger bone. In this
figure, one can see that the nail plate follows the shape of the
finger bone and the plate is fairly flat. |
|
Photographs: Milady's Standard
Textbook of Cosmetology |
|
Nail Growth
The matrix, the Mother of the Nail, is the part of the nail unit that lies underneath the
proximal nail fold just in front of the nail root. The leading
edge of the matrix is seen as the lunula. The matrix cannot be
seen on all nails, but is generally seen on the thumbs, index and middle
fingers. The soft, plump cells that comprise the nail plate are
developed in the matrix. As they grow out, they loose their inner
material and become flat, hard and translucent. The oldest cells
are the most compact, making the nail plate harder and more dense
closest to the free edge. The
longer the matrix, the more cells it can produce, resulting in a thicker
nail plate. Any damage to the matrix can be seen on the emerging
nail plate.
The nail plate is held together by strong,
interconnecting bands of protein fibers, and is kept flexible by a sticky residue of oils and
moisture that constantly flow upward from the nail bed. When this
residue transmits through the plate, it creates a matte shine on the
surface of the plate. It is also the substance that allows the
nail plate to bend and flex under pressure. The plate rides forward on
the nail bed in a 'rail and groove'' effect - much like a train riding
on its tracks. As we mature, the nail bed produces less oil and
moisture, and this rail and groove effect becomes evident as vertical ridges
in the plate.
Many factors determine nail growth, and each fingernail will grow at
different rates. Heredity and health determine how fast the
nail plate will grow, although the growth slows as we age. People who
use their hands a lot usually experience a faster growth
rate. The thumbnail will grow about 1 1/2 inches per
year, and the left thumb will usually grow faster than the right.
The index fingernail will grow the fastest, followed by the pointer and
ring finger, which grow at almost the same rate. As a rule, the
longer the finger, the faster the plate will grow. Nails also grow
faster in summer than in winter, and faster during pregnancy.
After pregnancy, the rate drops back to normal. Age also effects
the growth rate with nail growth peaking between 10 and 14
years and slowly declining after age 20. Factors that slow nail
growth include being immobilized or paralyzed, poor circulation,
malnutrition, lactation, serious infections, psoriasis and certain
medications. Some people erroneously believe that eating certain foods or using
special creams, oils or lotions will increase the growth rate.
Although the nail plate requires certain nutrients for proper growth,
there is very little evidence that eating any particular food will cause
them to grow faster. Creams, oils and lotions are sometimes sold
as 'growth accelerators', although these claims are false, misleading
and illegal. No cosmetic product may claim that it can alter or
change any body function. These products and others are only for
beautifying the nail plate, and only medical drugs can make such claims.
The Building Blocks
The nail plate cells are made of keratin which is a type of protein
composed of amino acids. A protein can be thought of as a long
chain that can be tied together like the rungs on a ladder to form a
'cross-link'. This cross linkage gives the nail plate strength,
while the oils and moisture form the 'cement' that hold the nail plate
cells together and keep them well lubricated, resulting in a strong, flexible nail.
We equate nail strength with hardness, though in actuality, nails are
only strong if they have a combination of strength, hardness and
flexibility. If something is strong, it simply means that it can
withstand the forces meant to break it. A glass rod is strong, but
can be easily broken. Hardness
measures how easily the plate is dented or scratched. Flexibility
determines how much the plate will bend. Strength shows
how likely the plate is to break under force, and Toughness is a combination
of these properties. The combination of strength and
flexibility create the ideal nail plate.
Many factors can cause changes in the nail plate, resulting in
lowered levels of strength and flexibility. For instance, water
will absorb into the nail plate causing the cells to shift and change
shape. Repeated or prolonged exposure to water can resulting in dry, split, brittle, or peeling nails.
Solvents will
also have a drying effect, although the effects are only temporary.
Repeated and prolonged contact with water (the universal solvent) or
other household solvents can have a lasting effect on the nail plate, or
result in irritant or allergic contact dermatitis from overexposure.
The symptoms of these two types of dermatitis will generally manifest itself as red, swollen, irritated
or itchy skin. Remove the 'allergen/irritant', and the symptoms will
disappear. This is why nail technicians across the country
recommend their clients wear protective gloves when exposing themselves
to excess amounts of water or household chemical solvents (cleaners).
Remember, everything we see and touch is a chemical except for light and
electricity. Some chemicals are more hazardous than others, which
is why reading the warning labels on the products we use and following
the manufacturers instructions for safe use are imperative.
Allergic contact dermatitis from overexposure to any potentially
hazardous chemical will remain with us for life. Every time we
expose ourselves to the 'allergen', an outbreak will occur.
Copyright © 2000
Marti Preuss
Hooked on Nails
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