Chapter 9 Nail structure and growth

hyponychium

slightly thickened layer of skin under the nail that lies between the fingertip and free edge of the natural nail plate.

sidewall

also known as lateral nail fold; the fold of skin overlapping the side of the nail.

natural nail

also known as onyx; the hard protective plate is composed mainly of keratin, the same fibrous protein found in skin and hair. The keratin in natural nails is harder than the keratin in the skin or hair.

matrix

area where the nail plate cells are formed; this area is composed of matrix cells that produce the nail plate.

nail unit

composed of several major parts of the fingernail including the nail plate, nail bed, matrix, cuticle, eponychium, hyponychium, specialized ligaments, and nail fold. Together, all of these parts form the nail unit.

cuticle

dead, colorless tissue attached to the natural nail plate.

nail folds

folds of normal skin that surround the natural nail plate

nail groove

furrow on each side of the nail.

nail plate

hardened keratin plate that sits on and covers the natural nail bed. It is the most visible and functional part of the natural nail unit.

eponychium

living skin at the base of the natural nail skate that covers the matrix.

free edge

part of the nail plate that extends over the tip of the finger or toe.

nail bed

portion of the living skin that supports the nail plate as it grows toward the free edge.

perionychium

the tissue bordering the root and sides of a fingernail or toenail.

bed epithelium

thin layer if tissue that attaches the nail plate and the nail bed.

ligament

tough band of fibrous tissue that connects bones or holds an organ in place.

lunula

visible part of the matrix that extends from underneath the living skin; it is the whitish, half moon shape at the base of the nail.

nail malformation

when the nail is abnormal in shape or form.