Lunula (anatomy) - Wikipedia

Crescent-shaped whitish bed of a fingernail or toenail For other uses, see Lunula.

Lunula
The lunula is the white crescent-shaped area at the base of a nail.
Details
Part of	Fingernail or toenail
Identifiers
Latin	lunula
TA98	A16.0.01.005
TA2	7067
TH	H3.12.00.3.02006
FMA	77858
Anatomical terminology[edit on Wikidata]

The lunula (pl.: lunulae; from Latin 'little moon') is the crescent-shaped whitish area of the bed of a fingernail or toenail.

In humans, it appears by week 14[1] 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

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The lunula 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 only appears so when it is seen through the nail. Outlining the nail matrix, the lunula is a very delicate part of the nail structure. If one damages the lunula, the nail will be permanently deformed. Even when the totality of the nail is removed, the lunula remains in place and is similar in appearance to another smaller fingernail embedded in the nail bed.

In most cases, it is half-moon-shaped and has unique histologic features. Examinations concluded that the lunula is an area of loose dermis with lesser developed collagen bundles. It appears whitish because a thickened underlying stratum basale obscures the underlying blood vessels.[2]

The lunula is most noticeable on the thumb; however, not everyone's lunulae are visible. In some cases, the eponychium may partially or completely cover the lunula.

Importance

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The lunula's location on the newest part of the nail allows assessments to be made about one's health. In some cases, its absence may indicate an underlying health problem. Some examples of such problems are malnourishment, anemia, kidney failure, and heart disease.[3]

See also

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• Nail disease

References

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1. ^ Cohen, P. R. (June 1996). "The lunula". Journal of the American Academy of Dermatology. 34 (6): 943–953, quiz 954–956. doi:10.1016/s0190-9622(96)90269-8. ISSN 0190-9622. PMID 8647987.
2. ^ Guglielmi, Giuseppe; Kuijk, Cornelis Van; Genant, Harry K (2001). Fundamentals of hand and wrist imaging. ISBN 978-3-540-67854-0.
3. ^ "No half-moon on nails: What does it mean?". www.medicalnewstoday.com. 2019-06-24. Retrieved 2022-03-21.

External links

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Media related to Lunula (nail) at Wikimedia Commons

v t e Skin and related structures
Skin	Epidermis Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Malpighian layer Stratum basale Basement membrane Basal keratinocyte Lamina lucida Lamina densa Dermis Papillary Dermal papillae Reticular
Subcutaneous tissue	Panniculus/Pannus (Panniculus adiposus Panniculus carnosus) Membranous layer Loose connective tissue Superficial fascia
Adnexa	Skin glands Sweat glands: Apocrine sweat gland Eccrine sweat gland Sebaceous Hair Root sheath Outer root sheath Inner root sheath Henle's layer Huxley's layer Hair shaft Cuticle Cortex Medulla Bulb with matrix cells Hair follicle Muscle Arrector pili muscle Pilosebaceous unit Hair sebaceous gland Nail Nail matrix Nail plate Lunula Eponychium Paronychium Hyponychium

Authority control databases	Terminologia Anatomica