This is where there is increased curvature of the nail with loss of the angle between the nail at its margin with the finger. It is associated with a number of disorders:
This is thought to be due to impaired lymphatic drainage. The nails - all of them - take on a yellow hue and there may be impaired growth. There is often accompanying pleural effusions (fluid on the lung) and swelling of the ankles.
Are a series of transverse (across the nail) depressions which represent a period of impaired growth. This may be due to an episode of severe illness (such as used to be seen with measles) or cytotoxic drugs used in the treatment of malignant disease. All nails are affected.
Are small longitudinal streaks - which look like splinters - where there has been bleeding under the nail. These can occur as a result of trauma (so are seen in manual labourers), in association with psoriasis or as a result of endocarditis - infection or inflammation of the lining of the heart or the heart valves.