lanula

Lanula, often spelled lunula, is the visible white crescent-shaped area at the proximal base of the fingernail or toenail. It marks the portion of the nail plate that overlies the nail matrix, the tissue responsible for creating the nail.

Anatomy and appearance: The lunula corresponds to the portion of the nail matrix that is visible through the nail plate. Its pale color arises because the matrix is thick and translucent, so light is reflected rather than tinted by underlying blood vessels. The remainder of the nail bed typically appears pink due to blood supply.

Variation and clinical relevance: The size and visibility of the lunula vary among individuals and across digits; in many people it is partially visible or obscured by the cuticle. Changes in the lunula are not diagnostic on their own, but marked alterations in size, shape, or color can be associated with systemic or local conditions, such as malnutrition, liver or kidney disease, or trauma. A lunula can be diminished or apparently absent in some individuals, and its appearance can change with aging or irritation.

Etymology and usage: The term lanula is a variant spelling of lunula, derived from the Latin luna for moon. Lunula is the more widely used term in anatomy, but lanula appears in some older or variant texts. In clinical practice, the focus remains on the nail matrix region and the overall health of the nail.