<unk>  are horizontal, going across the nailline, and should not be confused with vertical ridges going from the bottom (cuticle) of the nail out to the fingertip. These vertical<unk>  are usually a natural consequence of aging and are harmless.<unk>  should also be distinguished from Muehrcke's<unk>  of the fingernails. While<unk>  are actual ridges and indentations in the nail plate, Muehrcke<unk>  are areas of hypopigmentation without palpable ridges; they affect the underlying nail bed, and not the nail itself.<unk>  should also be distinguished from Mees'<unk>  of the fingernails, which are areas of discoloration in the nail plate. As the nail grows out, the ridge in the nail can be seen to move upwards until it reaches the fingertip. When it reaches this point the fingertips can become sore for a few days due to the nail bed being exposed by the mis-shapen nail.
Beau's lines
Pastia's lines
Gilula's lines
Langer's lines
Blaschko's lines
Schwalbe's line
Dandy's point
Burton's line