Anatomy, Physiology, and Nail Disorders and Diseases
The nail unit
Learn the parts and what each does. The matrix extends from the nail root and produces the nail plate; its visible portion is the lunula, and its shape determines the plate's thickness and curvature. The nail bed supports the plate, the eponychium is the living tissue at the base (the "cuticle" is the thin dead skin on the plate), the hyponychium seals under the free edge, and the lateral nail folds and grooves frame the sides. Fingernails grow roughly 3 mm (1/8 inch) per month; toenails are slower. Replacing a fingernail takes about four to six months, a toenail considerably longer.
Recognizing conditions
Onychocryptosis is an ingrown nail; onycholysis is separation of plate from bed; onychomadesis is separation at the base; onychorrhexis is brittleness with longitudinal splitting; leukonychia is white spotting; paronychia is bacterial inflammation of surrounding tissue; onychomycosis (tinea unguium) is a contagious fungal infection; pterygium is forward growth of the eponychium; Beau's lines are transverse depressions after illness or trauma; koilonychia is spooning.
Scope boundary
The nail technician observes and describes - never diagnoses or treats. Infected, inflamed, or broken skin means referral.
Traps and a rule of thumb
Questions love to swap "cuticle" and "eponychium," or to offer a treatment option for a fungal nail. Rule of thumb: decode the prefix - onycho = nail, mycosis = fungal (contagious, refer), itis = inflammation (refer).