Anatomy, Physiology, and Nail Disorders
Core concepts
Anatomy questions reward precise terms. The nail plate is keratinized and largely nonliving; the nail bed and matrix are living tissue. The matrix produces the plate; the lunula is visible matrix; the eponychium is the living proximal fold; the cuticle is the dead tissue seal; the hyponychium seals the free edge. Nail growth is slow-fingernails faster than toenails-and varies with age, circulation, and health.
Disorders include onychomycosis (fungal), paronychia (bacterial or inflammatory), onycholysis (separation), Beau's lines (growth interruption), koilonychia (spooning), pterygium (adhesion), and melanonychia (pigment band). Traps include diagnosing infection or fungus, treating a mold-like discoloration under acrylic as harmless, confusing cuticle with eponychium, and ignoring systemic signs. The nail technician's role is recognition and referral, not diagnosis or treatment.
Rule of thumb
Any new dark band, bleeding, pain, swelling, pus, or spreading redness gets referred.
Worked example
A client has green-black discoloration under an enhancement. Do not just file it off and continue. Remove the product safely, disinfect, advise evaluation, and do not reapply until cleared. Document objectively-green discoloration noted-not a diagnosis.