Cracked toenails with vertical lines, consider trauma, malnutrition, nail fungus and so on. 1. Trauma: If the toenail area has suffered from heavy objects or extrusion and other traumatic injuries, it will cause vertical cracking of the toenail, which is usually accompanied by under-nail bleeding, pain, and even swelling and other symptoms. 2. malnutrition: the growth of nails needs nutrition, if the patient usually has picky eating, or the body has some problems, resulting in insufficient supply of nutrients, will lead to nail malnutrition, the symptoms of vertical cracking. 3. ringworm of the nail: ringworm of the nail is also called gray nails, fungal infection caused by most of the feet of gray nails will also be accompanied by the symptoms of tinea pedis, mainly manifested as the deck appears cloudy, thickening, brittle, discoloration and shedding, some will also be manifested as vertical cracking. Toenails with vertical cracking may also be other reasons, it is recommended to go to the hospital for a detailed examination, by the doctor to clarify the cause of standardized treatment.