The nails are appendages of the skin resulting from a special type of keratinization, and designed to protect the extremities of the fingers and toes. The nail is developed from the nail matrix and so any lesion of this matrix will manifest itself in changes in the nail plate, e.g., atrophy or striation. In cases where the nail plate alone is involved the condition is called onychia; where the periphery is affected the term perionychia or paronychia is used.