Editing Uterus (section)

== Structure ==
[[File:3D Medical Animation Uterus.jpg|alt=Different regions of the uterus displayed and labelled using a 3D medical animation still shot|thumb|261x261px|Different regions of the uterus, and the [[vagina]], displayed and labelled using a 3D medical illustration]]

In humans, the uterus is located within the [[pelvis|pelvic region]] immediately behind and almost overlying the [[urinary bladder|bladder]], and in front of the [[sigmoid colon]]. The human uterus is pear-shaped and about {{Convert|7.6|cm|in|abbr=on}} long, {{Convert|4.5|cm|in|abbr=on}} broad (side to side), and {{Convert|3.0|cm|in|abbr=on}} thick.<ref name="Manual of Obstetrics">Manual of Obstetrics. (3rd ed.). Elsevier 2011. pp. 1–16. {{ISBN|9788131225561}}.</ref><ref>{{Cite book|title=Health & physical assessment in nursing|last=Donita|first=D'Amico|publisher=Pearson|others=Barbarito, Colleen|year=2015|isbn=9780133876406|edition=3rd |location=Boston|pages=645|oclc=894626609}}</ref> A typical adult uterus weighs about 60 grams. The uterus can be divided anatomically into four regions: the '''fundus''' – the uppermost rounded portion of the uterus above the openings of the [[fallopian tube]]s,<ref name="openstax">{{cite web |title=27.2 Anatomy and Physiology of the Female Reproductive System - Anatomy and Physiology {{!}} OpenStax |url=https://openstax.org/books/anatomy-and-physiology/pages/27-2-anatomy-and-physiology-of-the-female-reproductive-system#fig-ch28_02_06 |website=openstax.org |date=25 April 2013 |access-date=4 November 2022 |language=en}}</ref> the '''body''', the [[cervix]], and the [[cervical canal]]. The cervix protrudes into the [[vagina]]. The uterus is held in position within the pelvis by [[ligaments]], which are part of the [[endopelvic fascia]]. These ligaments include the [[pubocervical ligaments]], the [[cardinal ligament]]s, and the [[uterosacral ligament]]s. It is covered by a sheet-like fold of peritoneum, the [[broad ligament]].<ref>Gray's Anatomy for Students, 2nd edition</ref>

===Layers===
{|class="wikitable" align="right" style="margin-left:10px;"
|+ Uterine wall thickness (cm)<ref>{{cite book|author1=Nandita Palshetkar|author2=Rishma Dhillon Pai|author3=Hrishikesh D Pai|title=Textbook of Hysteroscopy|url=https://books.google.com/books?id=WW9bQtmpR3sC&pg=PA135|date=2012-09-30|publisher=JP Medical Ltd|isbn=978-93-5025-781-4|pages=135–}}</ref>
|-
! Location !! Mean (mm) !! Range (mm)
|-
| Anterior wall || 23 || 17 - 25
|-
| Posterior wall || 21 || 15 - 25
|-
| Fundus || 20 || 15 - 22
|-
| Isthmus || 10 || 8 - 22
|}

[[File:Gray1169.png|thumb|Vertical section of mucous membrane of human uterus]]
The uterus has three layers, which together form the '''uterine wall'''. From innermost to outermost, these layers are the [[endometrium]], [[myometrium]], and [[perimetrium]].<ref name="T and D">{{cite book |last1=Tortora |first1=G |last2=Derrickson |first2=B |title=Principles of anatomy & physiology. |date=2011 |publisher=Wiley |isbn=9780470646083 |page=1105 |edition=13th.}}</ref>

The endometrium is the inner [[Epithelium|epithelial layer]], along with its [[mucous membrane]], of the [[mammal]]ian uterus. It has a basal layer and a functional layer; the functional layer thickens and then is shed during the [[menstrual cycle]] or [[estrous cycle]]. During [[pregnancy]], the [[uterine gland]]s and [[blood vessel]]s in the endometrium further increase in size and number and form the [[decidua]]. Vascular spaces fuse and become interconnected, forming the [[placenta]], which supplies [[oxygen]] and nutrition to the [[embryo]] and [[fetus]].<ref name=histology>[http://www.lab.anhb.uwa.edu.au/mb140/CorePages/FemaleRepro/FemaleRepro.htm Blue Histology - Female Reproductive System] {{webarchive|url=https://web.archive.org/web/20070221174122/http://www.lab.anhb.uwa.edu.au/mb140/CorePages/FemaleRepro/FemaleRepro.htm |date=2007-02-21 }}. School of Anatomy and Human Biology&nbsp;— The University of Western Australia Accessed 20061228 20:35</ref><ref name=Guyton2006>{{cite book | title =Textbook of Medical Physiology | chapter = Chapter 81 Female Physiology Before Pregnancy and Female Hormones | pages = 1018ff | edition = 11th |veditors = Guyton AC, Hall JE | publisher = Elsevier Saunders | year = 2006 | isbn = 9780721602400}}</ref>

The myometrium of the uterus mostly consists of [[smooth muscle]]. The innermost layer of myometrium is known as the '''junctional zone''', which becomes thickened in [[adenomyosis]].<ref>{{Cite web|url=https://www.cancer.gov/publications/dictionaries/cancer-terms|title=NCI Dictionary of Cancer Terms|website=National Cancer Institute|access-date=2017-12-27|url-status=live|archive-url=https://web.archive.org/web/20171226183201/https://www.cancer.gov/publications/dictionaries/cancer-terms|archive-date=2017-12-26}}</ref>

The perimetrium is a [[serous membrane|serous]] layer of visceral [[peritoneum]]. It covers the outer surface of the uterus.<ref>{{cite book |last1=Ross |first1=Michael H. |last2=Pawlina |first2=Wojciech|edition=Sixth |title=Histology, a text and atlas|page=848}}</ref>

Surrounding the uterus is a layer or band of fibrous and fatty connective tissue called the [[parametrium]] that connects the uterus to other tissues of the pelvis.

[[Commensalism|Commensal]] and [[Mutualism (biology)|mutualistic]] organisms are present in the uterus and form the [[uterine microbiome]].<ref name="FranasiakScott2015">{{cite journal|last1=Franasiak|first1=Jason M.|last2=Scott|first2=Richard T.|title=Reproductive tract microbiome in assisted reproductive technologies|journal=Fertility and Sterility|volume=104|issue=6|year=2015|pages=1364–1371|issn=0015-0282|doi=10.1016/j.fertnstert.2015.10.012|pmid=26597628 |doi-access=free}}</ref><ref name="Verstrael6">{{cite journal|last1=Verstraelen|first1=Hans|last2=Vilchez-Vargas|first2=Ramiro|last3=Desimpel|first3=Fabian|last4=Jauregui|first4=Ruy|last5=Vankeirsbilck|first5=Nele|last6=Weyers|first6=Steven|last7=Verhelst|first7=Rita|last8=De Sutter|first8=Petra|last9=Pieper|first9=Dietmar H.|last10=Van De Wiele|first10=Tom|title=Characterisation of the human uterine microbiome in non-pregnant women through deep sequencing of the V1-2 region of the 16S rRNA gene|journal=PeerJ|volume=4|year=2016|pages=e1602|issn=2167-8359|doi=10.7717/peerj.1602|pmid=26823997|pmc=4730988 |doi-access=free }}</ref><ref name="MorKwon2015">{{cite journal|last1=Mor|first1=Gil|last2=Kwon|first2=Ja-Young|title=Trophoblast-microbiome interaction: a new paradigm on immune regulation|journal=American Journal of Obstetrics and Gynecology|volume=213|issue=4|year=2015|pages=S131–S137|issn=0002-9378|doi=10.1016/j.ajog.2015.06.039| pmid=26428492|pmc=6800181}}</ref><ref name="PayneBayatibojakhi2014">{{cite journal|last1=Payne|first1=Matthew S.|last2=Bayatibojakhi|first2=Sara|title=Exploring Preterm Birth as a Polymicrobial Disease: An Overview of the Uterine Microbiome|journal=Frontiers in Immunology|volume=5|year=2014|issn=1664-3224|doi=10.3389/fimmu.2014.00595|pmid=25505898|pmc=4245917|pages=595|doi-access=free}}</ref>

=== Support ===
[[File:Gray1161.png|thumb|right|220px|Uterus covered by the broad ligament]]
The uterus is primarily supported by the [[pelvic diaphragm]], [[perineal body]], and [[urogenital diaphragm]]. Secondarily, it is supported by ligaments, including the [[peritoneal ligament]] and the [[broad ligament of uterus]].<ref name=ucc>[http://www.ucc.ie/medsoc/1styr/resources/anatomy/The%20Pelvis.doc The Pelvis] University College Cork Archived from [https://web.archive.org/web/20080227041631/http://www.ucc.ie/medsoc/1styr/resources/anatomy/The%20Pelvis.doc the original] on 2008-02-27</ref>

==== Major ligaments ==== <!--Major ligaments of uterus redirects here-->
The uterus is held in place by several peritoneal ligaments, of which the following are the most important (there are two of each):

{| class="wikitable"
! Name !! From !! To
|-
| [[Uterosacral ligaments]] || Posterior cervix  || Anterior face of [[sacrum]]
|-
| [[Cardinal ligaments]] || Side of the cervix || [[Ischial spine]]s
|-
| [[Pubocervical ligaments]]<ref name=ucc/> ||Side of the cervix||[[Pubic symphysis]]
|}

=== Axis ===
Normally, the human uterus lies in anteversion and anteflexion. In most women, the long axis of the uterus is bent forward on the long axis of the vagina, against the urinary bladder. This position is referred to as anteversion of the uterus. Furthermore, the long axis of the body of the uterus is bent forward at the level of the internal os with the long axis of the cervix. This position is termed anteflexion of the uterus.<ref>Snell, Clinical Anatomy by regions, 8th edition</ref> The uterus assumes an anteverted position in 50% of women, a retroverted position in 25% of women, and a midposed position in the remaining 25% of women.<ref name="Manual of Obstetrics" />

=== Position ===
[[File:Figure 28 02 01.JPG|thumb|Uterus shown in position in the body]]

The uterus is located in the middle of the pelvic cavity, in the [[frontal plane]] (due to the [[broad ligament of the uterus]]). The fundus does not extend above the ''[[linea terminalis]]'', while the vaginal part of the cervix does not extend below the [[interspinal line]]. The uterus is mobile and moves posteriorly under the pressure of a full bladder, or anteriorly under the pressure of a full rectum. If both are full, it moves upwards. Increased intra-abdominal pressure pushes it downwards. The mobility is conferred to it by a musculo-fibrous apparatus that consists of suspensory and sustentacular parts. Under normal circumstances, the suspensory part keeps the uterus in anteflexion and anteversion (in 90% of women) and keeps it "floating" in the pelvis. The meanings of these terms are described below:
[[File:Uterus image-Photoroom.png|thumb|Top-down view of the uterus and other pelvic organs, here depicted as they are usually positioned inside the body<ref>{{Cite book |last=Bohannon |first=Cat |title=[[Eve: How the Female Body Drove 200 Million Years of Human Evolution]] |date=October 3, 2024 |publisher=[[Penguin Random House]] |isbn=978-0385350549 |pages=76 |quote=Female pelvic anatomy: it's a tight fit.}}</ref>]]
{| class="wikitable"
! Distinction !! More common !! Less common
|-
| Position tipped || "Anteverted": Tipped forward || "[[Retroverted uterus|Retroverted]]": Tipped backwards
|-
| Position of fundus || "Anteflexed": Fundus is pointing forward relative to the cervix || "Retroflexed": Fundus is pointing backward
|}
[[File:Positions of the human uterus 1.png|thumb|1. Anteversion with slight anteflexion<br>
2. Anteversion with marked anteflexion<br>
3. Anteversion with retrocession<br>
4. Retroversion<br>
5. Retroversion with retroflexion|left]]
The sustentacular part supports the pelvic organs and comprises the larger [[pelvic diaphragm]] in the back and the smaller [[urogenital diaphragm]] in the front.

The pathological changes of the position of the uterus are:
* [[Retroverted uterus|retroversion]]/retroflexion, if it is fixed
* hyperanteflexion&nbsp;– tipped too forward; most commonly congenital, but may be caused by tumors
* anteposition, retroposition, lateroposition&nbsp;– the whole uterus is moved; caused by [[parametritis]] or tumors
* elevation, descensus, [[Uterine prolapse|prolapse]]
* rotation (the whole uterus rotates around its longitudinal axis), torsion (only the body of the uterus rotates around)
* inversion

In cases where the uterus is "tipped", also known as [[retroverted uterus]], the woman may have symptoms of pain during sexual intercourse, pelvic pain during menstruation, minor incontinence, urinary tract infections, fertility difficulties,<ref>{{cite web |url=http://www.womens-health.co.uk/retrover.asp |title=Retroverted Uterus: What it is & How it Affects Pregnancy |website=www.womens-health.co.uk |url-status=live |archive-url=https://web.archive.org/web/20131005022310/http://www.womens-health.co.uk/retrover.asp |archive-date=2013-10-05}}</ref> and difficulty using tampons. A pelvic examination by a doctor can determine if a uterus is tipped.<ref>[http://www.americanpregnancy.org/womenshealth/tippeduterus.html Tipped Uterus:Tilted Uterus] {{webarchive |url=https://web.archive.org/web/20110224161243/http://www.americanpregnancy.org/womenshealth/tippeduterus.html |date=2011-02-24 }} AmericanPregnancy.org. Accessed 25 March 2011</ref>

=== Blood, lymph, and nerve supply ===
[[File:Uterine arterial vasculature.svg|thumb|150px|Diagram of uterine blood supply]]
The human uterus is supplied by arterial blood both from the [[uterine artery]] and the [[ovarian artery]]. Another anastomotic branch may also supply the uterus from anastomosis of these two arteries.

Afferent nerves supplying the uterus are [[Spinal nerves#Thoracic nerves|T11 and T12]]. Sympathetic supply is from the [[Superior hypogastric plexus|hypogastric plexus]] and the [[ovarian plexus]]. Parasympathetic supply is from the S2, S3 and S4 nerves.