Anatomy of the Nail

To have a better understanding of how onychomycosis affects the nail, a general knowledge of the anatomy of the nail is helpful (see Multimedia File 1). The nail, or nail unit, consists of the following parts:

• The nail matrix (where the nail starts) is where nail cells multiply and keratinize (harden and form into nail material) before being incorporated into the fingernail or toenail. Most of the matrix is not visible. The matrix starts under the skin 5 mm below the nail fold (the area of the cuticle where the finger or toe skin meets the nail) and covers the area called the lunula, or half moon (the white half moon-shaped area at the bottom of the nail).



• The cuticle is a fold of modified skin where the finger or toe meets the nail. The cuticle protects the matrix from infection.



• The nail plate is the nail itself.



• The nail bed is the soft tissue underneath the nail, anchoring the nail plate. The nail plate protects the nail bed.