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{{short description|Crescent-shaped whitish bed of a fingernail or toenail}}
{{Other uses|Lunula (disambiguation){{!}}Lunula}}
{{Other uses|Lunula (disambiguation){{!}}Lunula}}
{{Infobox anatomy
{{Infobox anatomy
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| Latin = lunula
| Latin = lunula
| Image = Fingernail label (enwiki).jpg
| Image = Fingernail label (enwiki).jpg
| Caption = The ''lunula'' is the white crescent-shaped area of a finger.
| Caption = The ''lunula'' is the white crescent-shaped area at the base of a nail.
| Image2 =
| Image2 =
| Caption2 =
| Caption2 =
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| PartOf = [[Fingernail]] or [[toenail]]
| PartOf = [[Fingernail]] or [[toenail]]
}}
}}
The '''lunula''', or '''lunulae''' (pl.) ({{ety|la||little moon}}), is the crescent-shaped whitish area of the bed of a [[fingernail]] or [[toenail]]. The lunula is the visible part of the root of the nail.
The '''lunula''' ({{plural form}}: '''lunulae'''; {{ety|la||little moon}}) is the crescent-shaped whitish area of the bed of a [[fingernail]] or [[toenail]].


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).
In humans, it appears by week 14<ref>{{Cite journal |last=Cohen |first=P. R. |date=June 1996 |title=The lunula |url=https://pubmed.ncbi.nlm.nih.gov/8647987/ |journal=Journal of the American Academy of Dermatology |volume=34 |issue=6 |pages=943–953; quiz 954–956 |doi=10.1016/s0190-9622(96)90269-8 |issn=0190-9622 |pmid=8647987}}</ref> 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==
==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 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 (anatomy)#Structure|nail bed]].
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 (anatomy)#Structure|nail bed]].


In most cases, it is half-moon-shaped and has unique [[Histology|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.<ref name="Fundamentals of hand and wrist imaging">{{Cite book | url = https://books.google.com/books?id=qTCbB2N2UFcC&q=lunula+histologic&pg=PA489 | title = Fundamentals of hand and wrist imaging | isbn = 978-3-540-67854-0 | last1 = Guglielmi | first1 = Giuseppe | last2 = Kuijk | first2 = Cornelis Van | last3 = Genant | first3 = Harry K | year = 2001}}</ref>
In most cases, it is half-moon-shaped and has unique [[Histology|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.<ref name="Fundamentals of hand and wrist imaging">{{Cite book | url = https://books.google.com/books?id=qTCbB2N2UFcC&q=lunula+histologic&pg=PA489 | title = Fundamentals of hand and wrist imaging | isbn = 978-3-540-67854-0 | last1 = Guglielmi | first1 = Giuseppe | last2 = Kuijk | first2 = Cornelis Van | last3 = Genant | first3 = Harry K | year = 2001}}</ref>


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.
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 ==
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.<ref>{{Cite web |date=2019-06-24 |title=No half-moon on nails: What does it mean? |url=https://www.medicalnewstoday.com/articles/325540 |access-date=2022-03-21 |website=www.medicalnewstoday.com |language=en}}</ref>

==See also==
==See also==
* [[Nail disease]]
* [[Nail disease]]


==References==
==References==
<references />
{{Reflist}}

{{Integumentary system}}
{{Integumentary system}}
{{Authority control}}
{{Authority control}}

Latest revision as of 20:05, 15 November 2024

For other uses, see Lunula.
Lunula
The lunula is the white crescent-shaped area at the base of a nail.
Details
Part ofFingernail or toenail
Identifiers
Latinlunula
TA98A16.0.01.005
TA27067
THH3.12.00.3.02006
FMA77858
Anatomical terminology

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

[edit]

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

[edit]

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

[edit]

References

[edit]
  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.
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