Editing Navel (section)

==Structure==
{{See also|Umbilical vein|Umbilical artery}}
[[File:Da Vinci Vitruve Luc Viatour.jpg|thumb|upright|The navel is the centre of the circle in this drawing of the ''[[Vitruvian Man]]'' by [[Leonardo da Vinci]].]]

The umbilicus is used to visually separate the abdomen into quadrants.<ref name="Openstax Anatomy & Physiology">{{cite web | url=http://cnx.org/content/col11496/latest/ | title=Anatomy & Physiology | date=25 April 2013 | publisher=Openstax college at Connexions | access-date=16 November 2013}}</ref>

The umbilicus is a prominent [[Scar#Umbilical|scar]] on the abdomen, with its position being relatively consistent among humans. The skin around the waist at the level of the umbilicus is supplied by the tenth thoracic [[spinal nerve]] (T10 [[dermatome (anatomy)|dermatome]]). The umbilicus itself typically lies at a vertical level corresponding to the junction between the L3 and L4 [[vertebrae]],<ref>{{cite book |last=Ellis |first=Harold |title=Clinical Anatomy: Applied Anatomy for Students and Junior Doctors |publisher=Wiley |location=New York |year=2006 |isbn=1-4051-3804-1 }}{{page needed|date=August 2015}}</ref> with a normal variation among people between the L3 and L5 vertebrae.<ref>{{cite book|last1=O'Rahilly|first1=Ronan|title=Basic Human Anatomy: A Regional Study of Human Structure|last2=Müller|first2=Fabiola|last3=Carpenter|first3=Stanley|last4=Swenson|first4=Rand|publisher=Dartmouth Medical School|year=2004|chapter=Abdominal walls|chapter-url=http://www.dartmouth.edu/~humananatomy/part_5/chapter_25.html|archive-url=https://archive.today/20120724132801/http://www.dartmouth.edu/~humananatomy/part_5/chapter_25.html|archive-date=24 July 2012|url-status=dead|access-date=10 November 2010}}</ref>

Parts of the adult navel include the "umbilical cord remnant" or "umbilical tip", which is the often protruding scar left by the detachment of the umbilical cord. This is located in the center of the navel, sometimes described as the ''belly button''. Around the cord remnant is the "umbilical collar", formed by the dense fibrous [[umbilical ring]]. Surrounding the umbilical collar is the periumbilical skin. Directly behind the navel is a thick fibrous cord formed from the umbilical cord, called the [[urachus]], which originates from the [[bladder]].<ref name=Parts>{{cite journal |last1=Khati |first1=Nadia J. |last2=Enquist |first2=Erik G. |last3=Javitt |first3=Marcia C. |title=Imaging of the Umbilicus and Periumbilical Region |journal=Radiographics |volume=18 |issue=2 |pages=413–4 |year=1998 |doi=10.1148/radiographics.18.2.9536487|pmid=9536487 }}</ref>

The belly button is unique to each individual due to its being a scar, and various general forms have been classified by medical practitioners.<ref>{{cite book |last=Shiffman |first=Melvin |title=Adult Umbilical Reconstruction: Principles and Techniques |publisher= Springer |location=Switzerland |year=2017 |isbn=978-3-319-43885-6 |page=53 |chapter=7.3 }}</ref><ref name=Types>{{cite book |last=Mohamed |first=Fahmy |chapter=Umbilicus Types and Shapes |publisher=Springer |location=Egypt |year=2018 |doi=10.1007/978-3-319-62383-2_22 |pages=105–8 |title=Umbilicus and Umbilical Cord |isbn=978-3-319-62382-5 }}</ref>{{Explain|date=November 2021}}

*'''Outie''': A navel consisting of the umbilical tip protruding past the periumbilical skin is an outie. Essentially any navel which is not concave.
**'''Swirly/spiral''': A rare form in which the umbilical cord scar forms a swirl shape.
**'''Split''': The protruding umbilical cord scar extends outwards, but is cleft in two by a fissure which extends part or all the way through the umbilical cord scar. This form is similar in appearance to a coffee bean.
**'''Protrusion''': The umbilical cord remnant is completely divulged, exposing the full umbilical scar.
**'''Circlet''': Although the entirety of the umbilical cord remnant sits out with the umbilical collar, the centre of the knot is inset by a deep fissure. Unlike a split outie, in this form the fissure is contained centrally and does not extend past the umbilical cord remnant in any direction, much akin to a 'donut' shape.<ref>{{cite book |last=Stephen Cullen |first=Thomas |title=Umbilicus |chapter-url=https://archive.org/details/embryologyanatom00culluoft |publisher= W.B.Saunders Company |location=Australia |year=1916 |isbn=978-0-7334-2609-4 |page=1.1–1.7 |chapter=2 }}</ref>
*'''Innie''': A navel in which the umbilical tip does not protrude past the periumbilical skin. Any navel which is concave.
**'''Round''': Round navels are completely circular with no hooding.
**'''Vertical''': Some navels present in the form of a more elongate hollow parallel with the [[Linea alba (abdomen)|linea alba]].
**'''Oval''': This form consists of three variants; superior hooding, inferior hooding, no hooding.
**'''T-shaped''': As the name states, the scar is in the shape of a T, and may have superior hooding to various extent.
**'''Horizontal''': The scar is the least visible, as the natural lines of the [[tendinous intersection]] fold over the scar.
*'''Distorted''': Any navel which does not fit well into any of the other categories.

<gallery widths="200" heights="200">
File:T-shaped navel.jpg|A "T"-shaped "innie" navel
File:Female Outie 2.jpg|An outie navel
</gallery>