Fingernails

Ungues manus

Integumentary (skin)SkinArmLeft and right

View left in 3D View right in 3D

What it is

Five translucent plates of hard keratin on the backs of the distal phalanges, each growing from a matrix under the proximal nail fold; the pale half-moon (lunula) is the visible front of the matrix.

Function

Protect the fingertips, provide counter-pressure that sharpens fine touch, and help pick up small objects.

Size

~10–12 mm long, ~0.5 mm thick; grow ~3 mm per month (a whole nail regrows in ~6 months)

Clinical note

Nail changes can reveal systemic disease: clubbing (lung disease), spoon nails (iron deficiency), pitting (psoriasis), Beau lines (a past severe illness).