Nail Structure and Growth

Question 1

natural nail unit

Answer 1

all parts of the finger from the tip to the first knuckle; technically referred to as the onyx and is composed mainly of keratin

Question 2

Onyx

Answer 2

technical term for nails of the fingers or toes

Question 3

perionychium

Answer 3

collectively; the nail bed (or sterile matrix); nail fold, eponychium, and hyponychium

Question 4

Nail folds

Answer 4

folds of skin that surround the nail plate

Question 5

nail groove

Answer 5

slit or furrow on the sides of the nail

Question 6

Lateral nail fold

Answer 6

also known as the sidewall; folds of skin that line the sides of the nail plate

Question 7

proximal nail fold

Answer 7

abbreviated PNF; entire flap of skin covering the matrix, extending from the edge of the visible nail plate to the first joint of the finger or toe

Question 8

Nail plate

Answer 8

hard keratin plate on top of and slowly sliding across the nail bed as it grows; the most visible and functional part of the nail unit

Question 9

free edge

Answer 9

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

Question 10

nail bed

Answer 10

also known as sterile matrix, is the portion of living skin that supports the nail plate as it grows toward the free edge. Because it is richly supplied with blood vessels, the area under the nail plate can have a pinkish appearance in the area that extends from the lunula to the area just before the nail’s free edge.

Question 11

bed epithelium

Answer 11

thin layer of tissue between the nail plate and the nail bed

Question 12

matrix

Answer 12

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

Question 13

lunula

Answer 13

visible part of the matrix that extends from underneath the living skin; whitish half-moon shape at the base of the nail

Question 14

cuticle

Answer 14

the nonliving colorless tissue attached to the nail plate and comes from the eponychium located on the underside of the skin lying above the natural nail plate; prevents infectious organisms from getting underneath the skin and infecting the matrix or bone.

Question 15

eponychium

Answer 15

the living skin underneath the PNF found at the nail plate’s base covering the matrix area

Question 16

hyponychium

Answer 16

the slightly thickened skin layer between the fingertip and the nail plate’s free edge. It forms a protective barrier that prevents microorganisms from invading and infecting the nail bed.

Question 17

ligament

Answer 17

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

Question 18

Speed of nail growth

Answer 18

The average nail plate growth rate in the typical adult is about 1/10 to 1/8 inch (2.5 to 3 millimeters) per month

Question 19

Healthy water content of a nail

Answer 19

15%-25%