Lunula

The lunula is the white crescent-shaped area of this finger.

The lunula, or lunulae (pl.) (nail moon), is the crescent-shaped whitish area of the bed of a fingernail or toenail. The lunula is the visible part of the nail matrix (i.e. the root of the nail).

In humans, it appears by week 14 of gestation, and has a primary structural role in defining the free edge of the distal nail plate (the part of the nail that grows outward).

Appearance

It is located at the end of the nail (that is closest to the skin of the finger), but it still lies under the nail. It is not actually white, but it only appears so, when it is seen through the nail.

It is half-moon-shaped, and has unique histologic features.^[vague]

The lunula is most noticeable on the thumb. Not everyone's lunula is visible.

Clinical significance

The lunula can show the health of a body, and the nail itself are good places to find warning signs of certain diseases such as liver disease, kidney disease, heart problems and lung diseases.^[1] Any color differences or unusual lines may indicate some type of disease or insufficiency. However, vertical lines on one's fingernails are normal as one ages.

Lunular anomalies include changes in form, structure or color. Lunular dysmorphologic features (anomalies in form) can be characterized by macrolunula, microlunula or anolunula, and nonconvex lunula. Lunular dyschromias (color anomalies) can be confluent or spotted or can be characterized by longitudinal colored bands that traverse the lunula. Alterations in the morphologic features or color (or both) of the lunula can be an indication of either a cutaneous or a systemic disorder. A deep red lunula (and a pale nail) is associated with congestive heart failure.

Notes

See also

• Nail
• Nail disease