Final answer:
Horizontal wavy ridges across the nail, known as Beau's lines, can be caused by trauma, illness, nutritional deficiencies, or systemic diseases.
Step-by-step explanation:
Horizontal wavy ridges across the nail are often referred to as Beau's lines. They are characterized by depressions or grooves that run horizontally across the nail plate. Beau's lines can be caused by various factors, including trauma, illness, nutritional deficiencies, or systemic diseases.
For example, if a person experiences a severe illness or high fever, it can interrupt nail growth and result in the formation of Beau's lines. Similarly, malnutrition or a deficiency in certain nutrients like zinc or vitamin B12 can affect nail health and cause these ridges to appear.
If you notice horizontal ridges on your nails, it may be a good idea to consult a healthcare professional to determine the underlying cause and receive appropriate treatment if necessary.