Nail and Nail Disorders

The nail unit is a dynamic complex which forms an important part of the integument. This complex consists of the nail matrix (NM), nail bed (NB), hyponychium, nail fold (NF) and the nail plate (NP). Cells of the nail matrix, under the protection of the proximal nail fold mature and keratinised to form the NP. The NM contributes to the most portion of the NP while about 10-15% is produced by the NB. As the NP grows distally, the continued addition of keratinised material makes the NP increases in thickness while it lengthens distally. There are variations in the rate of growth between different nails such that the middle finger (longest digit) grows the fastest. Finger nails grow faster than toe nails. A finger nail grows about 1 cm in 3 months while a toe nail only grows about 1 cm in 9 months. Nail growth can be affected by many factors (Table 1).