There are many causes of right thumb nail depression, such as trauma, malnutrition, skin diseases and other causes. 1. Trauma: The nail is subjected to external stimuli such as extrusion and impact, which may cause the symptoms of right thumb nail depression. 2. Malnutrition: anemia or vitamin deficiency, lack of trace elements, heart disease, etc., may affect the local blood and oxygen supply, which may lead to the appearance of the right thumb nail depression. 3. Skin diseases: lichen planus, onychomycosis, psoriasis, etc., may also lead to right thumb nail depression. There may be other reasons for the right thumbnail depression, it is recommended to go to the hospital in time to check, clarify the cause of the disease and follow the doctor’s instructions for treatment.