What is the fold of skin overlapping the side of the nail called?

The fold of skin overlapping the side of the nail is known as the sidewall. This area plays a significant role in protecting the nail matrix and maintaining the overall health of the nail. Sidewalls help to prevent debris and pathogens from entering underneath the nail, which could cause infections or other disorders.

Other terms like eponychium and hyponychium refer to different parts of the nail structure. The eponychium is the thickened layer of skin that overlaps the base of the nail, while the hyponychium is the area of skin under the free edge of the nail. The nail groove, on the other hand, refers to the indentation along the sides of the nail where the nail sits, not necessarily the overlapping skin. The sidewall's protective function and its specific location make it a critical component of nail anatomy.