The nail bed is the skin beneath the nail plate.[7] Like all skin, it is made of two types of tissues: the deeper dermis, the living tissue which includes capillaries and glands,[8] and the epidermis, the layer just beneath the nail plate, which moves toward the finger tip with the plate. The epidermis is attached to the dermis by tiny longitudinal "grooves"[5] called matrix crests (cristae matricis unguis).[3][8] In old age, the nail plate becomes thinner so that these grooves become more visible.[