The toenail Surface Anatomy

Location

The toenail grows from the nailfold located at the proximal head of each distal phalanx. The nailbed has a rich capillary supply which gives it a pink to red appearance. A lunula, or crescent shaped white area at the base of the nail may be present.

Significance

Swelling, tenderness, and erythema along the lateral nail folds are signs of an ingrown toenail and are most commonly seen in the great toe. This may progress to form an abscess, where increased tenderness along with serous or purulent discharge may be seen. Eventually abundant granulation tissue may grow out over the nailbed and prevent drainage. Ingrown toenails may lead to secondary fungal or bacterial infections around the nailbeds, known as paronychia. Patients with ingrown toenails should be advised to cut their toenails straight across, and not in a crescent shape to avoid having the sharply cut surface in contact with the nailfold.

Fungal infections of the toenails are common, especially in older patients. Yellow to orange discoloration, along with hypertrophy, ridging, and difficulty trimming the toenails are common symptoms. Trichophyton rubrum and Trichophyton mentagrophytes cause a majority of fungal infections.

Trauma or repetitively applying pressure to a toe may cause a subungual hematoma. It will appear as a maroon to black accumulation of blood under the nail, which can be as large as the entire toenail. Draining the hematoma or removing the nail may be necessary to relieve pressure.

Malignant melanomas may be visible through the nail as a dark discoloration. They may at first appear benign, but should be monitored for aggressive growth.