eponychium

The eponychium is the narrow band of living skin at the base of a fingernail or toenail that overlaps the nail matrix as part of the proximal nail fold. It is sometimes referred to as the cuticle, but anatomically the term cuticle can also include the hyponychium, which is located at the distal edge under the nail plate.

Anatomically, the eponychium lies at the proximal end of the nail plate and helps form a protective seal over the matrix. This area is made of living skin and is continuous with the surrounding proximal nail fold. The border between the eponychium and the nail bed is the eponychial fold.

Functionally, the eponychium serves as a protective barrier that helps prevent pathogens from entering the matrix and nail bed and contributes to moisture retention in the proximal nail area. Its appearance and thickness can vary among individuals and across digits.

In clinical practice, trauma to the eponychium or excessive trimming can lead to irritation, inflammation, or infection such as paronychia. Many professionals advise careful handling during manicure procedures to avoid injuring the tissue. The eponychium should not be confused with the hyponychium, which is the skin located under the distal edge of the nail.