lunula

The lunula, from Latin lunula meaning "little moon," is the visible portion of the nail matrix at the base of the fingernail or toenail. It appears as a pale, crescent-shaped area that is most easily seen on the thumbs but can vary in prominence between individuals and across different nails. The lunula sits beneath the proximal nail fold, where the matrix produces the keratin that forms the nail plate.

Color and visibility depend on the thickness and translucency of the nail plate and the skin tone beneath. The pale appearance is due to the thicker, less pigmented matrix tissue and the way light reflects through the nail plate rather than blood supply in the bed. Some people have a very small or less noticeable lunula on certain nails, and growth conditions can influence how much of the matrix is visible.

Clinical notes: The lunula is a normal anatomical feature; its presence or absence alone is not a reliable sign of disease. Various factors, including age, injury, or changes in nail growth, can affect its visibility. If there are accompanying changes in nail color, shape, texture, or new lesions, a medical evaluation is advised. The term simply reflects a historic observation of a crescent-shaped region at the nail base.