Many disorders can affect the nails, including deformity and dystrophy Deformities, Dystrophies, and Discoloration of the Nails The terms deformities and dystrophies are often used interchangeably, sometimes even by doctors. However, their meanings are slightly different. Deformities: Changes in nail shape Dystrophies... read more , infections, and ingrown toenails Ingrown Toenail An ingrown toenail is a condition in which the edges of the nail grow into the surrounding skin. (See also Overview of Nail Disorders.) An ingrown nail can result when a deformed toenail grows... read more . Infections can involve any part of the nail and may or may not change the nail's appearance. Most nail infections are fungal (onychomycosis Onychomycosis Onychomycosis is a fungal infection of the nails. (See also Overview of Nail Disorders.) About 10% of people have onychomycosis, which most often affects the toenails rather than the fingernails... read more ), but bacterial and viral infections occur.
The nail unit is made up of the nail plate (the hard part of the nail made of the protein keratin) and the surrounding structures. The nail bed is underneath the nail and attaches the nail to the finger. The nail matrix is located at the base of the nail and is where nail growth originates. The cuticle connects the top of the nail plate to the skin behind it. The lunula is the half-moon shape at the base of the nail. The nail folds are the folds of hard skin at the sides of the nail plate where the nail and the skin meet.
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Causes of Nail Disorders
Some of the causes of nail disorders include the following:
Infections (such as paronychia Acute Paronychia Acute paronychia is a bacterial infection of the cuticle. In acute paronychia, bacteria (usually Staphylococcus aureus or streptococci) enter through a break in the skin resulting from a hangnail... read more , warts Verruca Vulgaris Verruca vulgaris is the common wart. Verruca vulgaris are common warts, which are caused by infection with human papillomavirus. Such warts can develop anywhere on the skin and frequently appear... read more , and green nail syndrome Green Nail Syndrome Green nail syndrome is infection with Pseudomonas, a type of bacteria. (See also Overview of Nail Disorders.) The photo on the left shows green nail syndrome with onycholysis of the fourth fingernail... read more )
Internal diseases (such as certain lung diseases, which can cause yellow nail syndrome)