& Healing Centre
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Hair and Nails.
Hair can be divided into three parts length-wise, (1) the bulb,
a swelling at the base which originates from the dermis, (2) the root, which is
the hair lying beneath the skin surface, and (3) the shaft, which is the hair
above the skin surface. In cross-section, there are also three parts, (1) the
medulla, an area in the core which contains loose cells and airspaces (2) the
cortex, which contains densely packed keratin and (3) the cuticle, which is a
single layer of cells arranged like roof shingles.
Though human skin is "hairless", humans actually have the same number of hair
follicles per unit area as other primates. Human hair is barely visible as it is
thinner, shorter and more transparent than the hair of other mammals.
Historically, some ideas have been advanced to explain the apparent hairlessness
of humans, as compared to other species.
Most mammals have light skin that is covered by fur, and biologists believe that
human ancestors started out this way also. Dark skin probably evolved after
humans lost their body fur, because the naked skin was vulnerable to strong
African UV radiation. Therefore, evidence of when human skin darkened has been
used to date the loss of human body hair, assuming that the dark skin was needed
after the fur was gone.
Fingernails and toenails are made of a tough protein called keratin, as are
animals' hooves and horns. Along with hair and teeth they are an appendage of
the skin. The parts of the nail are:
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.
Paronychium: 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: This 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 determines 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.
The only living part of a nail is situated inside or underneath the epidermis.
