are deep grooved lines that run from side to side on the fingernail
. They may look like indentations or ridges in the nail plate. There are several reasons that humans get Beau's lines. It is believed that there is a temporary cessation of cell division
in the nail matrix
. This may be caused by an infection
or problem in the nail fold, where the nail begins to form, or it may be caused by an injury to that area. Some other reasons for these lines include: trauma, coronary occlusion, hypocalcaemia
, skin disease and may be a sign of systemic disease. It may also be caused by an illness of the body, such as diabetes
, certain drugs - including beta blockers according to the Cleveland Clinic, as well as other drugs used in chemotherapy
, or even malnutrition. This condition of the nail was named by a French physician, Joseph Honoré Simon Beau
(1806–1865), who first described it in 1846.
Beau's lines should be distinguished from Muehrcke lines of the fingernails. While Beau's lines are actual ridges and indentations in the nail plate, Muehrcke lines are areas of hypopigmentation without palpable ridges.
A researcher found Beau's lines in the fingernails of 6 divers following a deep saturation dive to a pressure equal to 335 meters of sea water, and in 2 of 6 divers following a similar dive to 305 meters.