The appearance of vertical lines on finger nails may be related to factors such as onychomycosis, micronutrient deficiency, and nail trauma. 1. ringworm of the nails: a skin disease formed after the nails are infected with ringworm, due to the destruction of the nail plate and nail bed caused by ringworm, it may lead to deformation of the nails, discoloration and other phenomena. 2. Micronutrient deficiency: when the body lacks micronutrients, it will directly affect the growth of nails, resulting in brittle nails, deformation phenomenon. 3. Nail trauma: Nail trauma can lead to nail deformation, including vertical and horizontal lines on the nail surface. As there are many factors affecting the nails, it is necessary to consult a doctor for specific cases.