View source for Urethra

{{short description|Tube that connects the urinary bladder to the external urethral orifice}}
{{distinguish|ureter}}
{{Infobox anatomy
| Name        = Urethra
| Latin       = urethra feminina (female); urethra masculina (male)
| Greek       = οὐρήθρα 
| Image       = Female and Male Urethra.jpg
| Caption     = The urethra transports urine from the bladder to the outside of the body. This image shows (a) a human female urethra and (b) a human male urethra.
| Width       = 220
| Image2      = 
| Caption2    = 
| Precursor   = [[Urogenital sinus]]
| System      = 
| Artery      = [[Inferior vesical artery]]<br />[[Middle rectal artery]]<br />[[Internal pudendal artery]]
| Vein        = [[Inferior vesical vein]]<br />[[Middle rectal vein]]<br />[[Internal pudendal vein]]
| Nerve       = [[Pudendal nerve]]<br />[[Pelvic splanchnic nerves]]<br />[[Inferior hypogastric plexus]]
| Lymph       = [[Internal iliac lymph nodes]]<br />[[Deep inguinal lymph nodes]]
}}

The '''urethra''' ({{plural form}}: '''urethras''' or '''urethrae''') is the tube that transports [[semen]] through the [[penis]] during [[ejaculation]] and [[urine]] from the [[urinary bladder]] to the [[urinary meatus|external urethral orifice]] of the penis or [[vulva]] in [[Placentalia|placental mammals]].<ref>{{Cite book |last=Lombardi |first=Julian |url=https://books.google.com/books?id=tXvjBwAAQBAJ&dq=meatus&pg=PA102 |title=Comparative Vertebrate Reproduction |date=2012-12-06 |publisher=Springer Science & Business Media |isbn=978-1-4615-4937-6 |language=en}}</ref><ref name="Wake1992">{{cite book|author=Marvalee H. Wake|title=Hyman's Comparative Vertebrate Anatomy|url=https://books.google.com/books?id=VKlWjdOkiMwC&q=placental+mammal+urethra&pg=PA583|access-date=6 May 2013|date=15 September 1992|publisher=University of Chicago Press|isbn=978-0-226-87013-7|pages=583–}}</ref><ref>{{Cite journal |last=Brading |first=Alison F. |date=January 1999 |title=The physiology of the mammalian urinary outflow tract |url=https://physoc.onlinelibrary.wiley.com/doi/10.1111/j.1469-445X.1999.tb00084.x |journal=Experimental Physiology |language=en |volume=84 |issue=1 |pages=215–221 |doi=10.1111/j.1469-445X.1999.tb00084.x |pmid=10081719 |issn=0958-0670|url-access=subscription }}</ref>

The external [[urethral sphincter]] is a [[striated muscle]] that allows voluntary control over [[urination]].<ref>{{cite book| title = Principles of Gender-specific Medicine | volume = 1 | chapter = 109: The Evaluation and Treatment of Urinary Incontinence | page = 1187 | publisher = Gulf Professional Publishing | year = 2004|editor-first= Marianne J. |editor-last=Legato|editor-first2=John P. |editor-last2=Bilezikian}}</ref> The [[Internal urethral sphincter|internal sphincter]], formed by the involuntary [[smooth muscles]] lining the bladder neck and urethra, is innervated by the [[Sympathetic nervous system|sympathetic]] division of the [[autonomic nervous system]]<ref name=Chancellor2004>{{cite journal |last1=Chancellor |first1=Michael B |last2=Yoshimura |first2=Naoki |title=Neurophysiology of Stress Urinary Incontinence |journal=Reviews in Urology |date=2004 |volume=6 |issue=Suppl 3 |pages=S19–S28 |pmid=16985861 |pmc=1472861 }}</ref> and is found both in males and females.<ref name=Jung2012>{{cite journal |last1=Jung |first1=Junyang |last2=Anh |first2=Hyo Kwang |last3=Huh |first3=Youngbuhm |date=September 2012 |title=Clinical and Functional Anatomy of the Urethral Sphincter |journal=International Neurourology Journal |volume=16 |issue=3 |pages=102–106 |pmid=23094214 |pmc=3469827 |doi=10.5213/inj.2012.16.3.102 |doi-access=free }}</ref><ref name=Karam2005>{{cite journal |last1=Karam |first1=I. |last2=Moudouni |first2=S. |last3=Droupy |first3=S. |last4=Abd-Almasad |first4=I. |last5= Uhl |first5= J. F. |last6=Delmas |first6=V. |date=April 2005 |title=The structure and innervation of the male urethra: histological and immunohistochemical studies with three-dimensional reconstruction |journal=Journal of Anatomy |volume=206 |issue=4 |pages=395–403 |pmid=15817107 |pmc=1571491 |doi=10.1111/j.1469-7580.2005.00402.x |doi-access=free }}</ref><ref name =AshtonMiller2007>{{cite journal |last1=Ashton-Miller |first1=J. A. |last2=DeLancey |first2=J. O. |date=April 2007 |title=Functional anatomy of the female pelvic floor. |s2cid-access=free |journal=Annals of the New York Academy of Sciences |volume=1101 |issue=1 |pages=266–296 |pmid=17416924 |doi=10.1196/annals.1389.034 |bibcode=2007NYASA1101..266A |hdl=2027.42/72597 |s2cid=6310287 |hdl-access=free |via=Deep Blue Documents |url=https://deepblue.lib.umich.edu/handle/2027.42/72597 |url-status=live |archive-url=https://web.archive.org/web/20230822142127/https://deepblue.lib.umich.edu/handle/2027.42/72597 |archive-date= Aug 22, 2023 }}</ref>

== Structure ==
The urethra is a fibrous and muscular tube which connects the [[urinary bladder]] to the [[external urethral meatus]]. Its length differs between the sexes, because it passes through the [[penis]] in males.

=== Male ===

[[File:Gray1142.png|thumb|The human male urethra laid open on its anterior (upper) surface]]

In the human male, the urethra is on average {{convert|18|to|20|cm|in|0|abbr=off|sp=us}} long and opens at the end of the external urethral meatus.<ref name=Grays2016 />

The urethra is divided into four parts in men, named after the location:<ref name=Grays2016 />

{| class="wikitable"
! width=120|Region !! Description !! [[Epithelium]]
|-
 | [[Pre-prostatic urethra]] || This is the intramural part of the urethra surrounded by the internal urethral sphincter and varies between 0.5 and 1.5&nbsp;cm in length depending on the fullness of the bladder. || [[Transitional epithelium|Transitional]]
|-
 | [[Prostatic urethra]] || Crosses through the [[prostate gland]]. There are several openings at the posterior wall:
# the [[ejaculatory duct]] (2 lateral) receives [[spermatozoon|sperm]] from the [[vas deferens]] and ejaculate fluid from the [[seminal vesicle]]
# the prostatic sinus which has openings for several prostatic ducts  where fluid from the [[prostate]] enters and contributes to the ejaculate
# the [[prostatic utricle]], which is merely an indentation.
These openings are collectively called the verumontanum (colliculus seminalis).
The prostatic urethra is a common site of obstruction to outflow of urine in BPH patients 
| [[Transitional epithelium|Transitional]]
 |-
 | [[Membranous urethra]] || A short (1 or 2&nbsp;cm) portion passing through the [[External sphincter muscle of male urethra|external urethral sphincter]]. This is the narrowest part of the urethra. It is located in the [[deep perineal pouch]]. The [[bulbourethral glands]] (Cowper's gland) are found posterior to this region but open in the [[spongy urethra]]. || [[Pseudostratified columnar]]
 |-
 | [[Spongy urethra]] (or ''penile urethra'') || Runs along the length of the penis on its ventral (underneath) surface. It is about 15 to 25&nbsp;cm in length,<ref>{{Cite web | url=https://www.centerforreconstructiveurology.org/urethral-stricture/intro-anatomy/ |title = Male Urethra Function & Urethra Anatomy Pictures |website=Center For Reconstructive Urology |url-status=live |archive-url= https://web.archive.org/web/20230926133006/https://www.centerforreconstructiveurology.org/urethral-stricture/intro-anatomy/ |archive-date= Sep 26, 2023 }}</ref> with steady diameter of 6 mm,<ref name="lumen-urethra">{{cite web |author1=Arcot J. Chandrasekhar, M.D. |author2=Hema Chandrasekhar, M.D. |author3=Jennifer Lim-Dunham, M.D. |title=Urethra |url=https://www.meddean.luc.edu/lumen/meded/radio/curriculum/gu/urethra.htm |website=Atlas of Radiological images to support Anatomy |publisher=Chicago's Jeasuit University |access-date=9 June 2024 |language=en |date=13 October 2010 }}</ref> and travels through the [[corpus spongiosum]]. The ducts from the [[urethral gland]] (gland of Littré) enter here. The openings of the [[bulbourethral glands]] are also found here.<ref>Atlas of Human Anatomy 5th Edition, Netter.</ref> Some textbooks will subdivide the spongy urethra into two parts, the bulbous and pendulous urethra. The urethral lumen runs effectively parallel to the penis, except at the narrowest point, the external urethral meatus, where it is vertical. This produces a spiral stream of urine and has the effect of cleaning the external urethral meatus. The lack of an equivalent mechanism in the female urethra partly explains why urinary tract infections occur so much more frequently in females. || [[Pseudostratified columnar]] – proximally<p>[[Stratified squamous]] – distally</p>
|}

There is inadequate data for the typical length of the male urethra; however, a study of 109 men showed an average length of 22.3&nbsp;cm (SD = 2.4&nbsp;cm), ranging from 15&nbsp;cm to 29&nbsp;cm.<ref>{{cite journal |vauthors=Kohler TS, Yadven M, Manvar A, Liu N, Monga M |title=The length of the male urethra |journal= International Brazilian Journal of Urology  |volume=34 |issue=4 |pages=451–4; discussion 455–6 |year=2008 |pmid=18778496 |url=http://www.brazjurol.com.br/july_august_2008/Kohler_ing_451_456.htm |doi=10.1590/s1677-55382008000400007|doi-access=free }}</ref>

The urethra in male placental mammals is typically longer than in females.<ref name="Hamilton">{{cite book|author=Marvalee H. Wake|title= Homeopathic Care for Cats and Dogs: Small Doses for Small Animals |url= https://books.google.com/books?id=nwQ3TvOMWxwC&pg=PA206|year=1999|publisher=North Atlantic Books|isbn= 978-1-55643-295-8 |page=206}}</ref>

=== Female ===
In the human female, the urethra is about 4&nbsp;cm long,<ref name=Grays2016>{{Cite book|title=Gray's Anatomy: The Anatomical Basis of Clinical Practice |publisher=Elsevier Limited |editor=Standring, Susan|isbn=978-0-7020-5230-9|edition=41st|location=Philadelphia|oclc=920806541|year=2016|chapter=Bladder, prostate and urethra|pages=1261–1266}}</ref><ref name="lumen-urethra"></ref> having 6 mm diameter,<ref name="lumen-urethra"/> and exits the body between the [[clitoris]] and the [[vaginal opening]], extending from the [[internal urethral orifice|internal]] to the [[external urethral orifice]]. The meatus is located below the clitoris. It is placed behind the [[symphysis pubis]], embedded in the anterior wall of the vagina, and its direction is obliquely downward and forward; it is slightly curved with the concavity directed forward. The proximal two-thirds of the urethra is lined by [[Epithelium#Stratified_epithelium|transitional epithelial cells]], while the distal third is lined by [[Epithelium#Cell_types|stratified squamous epithelial cells]].<ref>Manual of Obstetrics. (3rd ed.). Elsevier. pp. 1-16. {{ISBN|9788131225561}}.</ref>

Between the [[Superior fascia of the urogenital diaphragm|superior]] and [[perineal membrane|inferior fascia]] of the [[urogenital diaphragm]], the female urethra is surrounded by the [[urethral sphincter]].

The urethra in female placental mammals is typically shorter than in the male.<ref name="Hamilton"/>

=== Microanatomy ===
The cells lining the urethra (the [[epithelium]]) start off as [[Transitional epithelium|transitional cells]] as it exits the bladder, which are variable layers of flat to cuboidal cells that change shape depending on whether they are compressed by the contents of the urethra.<ref name=Wheaters2013>{{cite book |last1=Young |first1=Barbara |last2=O'Dowd |first2=Geraldine |last3=Woodford |first3=Phillip |title=Wheater's functional histology: a text and colour atlas.|publisher=Elsevier |location=Philadelphia |date=2013|isbn=978-0-7020-4747-3 |edition=6th|chapter=Male reproductive system|page=349}}</ref> Further along the urethra there are [[pseudostratified columnar epithelium|pseudostratified columnar]] and [[Stratified columnar epithelium|stratified columnar]] epithelia.<ref name=Wheaters2013 /> The lining becomes [[stratified squamous epithelium|multiple layers of flat cells]] near the end of the urethra, which is the same as the external skin around it.<ref name=Wheaters2013 />

There are small [[mucus]]-secreting urethral glands, as well as bulbo-urethral glands of Cowper, that secrete mucous acting to lubricate the urethra.<ref name=Wheaters2013 />

The urethra consists of three coats: muscular, erectile, and mucous, the muscular layer being a continuation of that of the bladder.

===Blood and nerve supply and lymphatics===
[[Somatic nervous system|Somatic]] (conscious) innervation of the [[External sphincter muscle of female urethra|external urethral sphincter]] is supplied by the [[pudendal nerve]].

==Development==
{{Further|Development of the urinary system}}
In the developing [[embryo]], at the hind end lies a [[Cloaca (embryology)|cloaca]]. This, over the fourth to the seventh week, divides into a [[urogenital sinus]] and the beginnings of the [[anal canal]], with a wall forming between these two inpouchings called the [[urorectal septum]].<ref name=Langman2019>{{cite book |last1=Sadley |first1=TW |title=Langman's medical embryology |date=2019|location=Philadelphia|publisher=Wolters Kluwer |isbn=978-1-4963-8390-7 |edition=14th|section=Bladder and urethra|pages=263–66}}</ref> The urogenital sinus divides into three parts, with the middle part forming the urethra; the upper part is largest and becomes the [[urinary bladder]], and the lower part then changes depending on the biological sex of the embryo.<ref name=Langman2019 /> The cells lining the urethra (the epithelium) come from [[endoderm]], whereas the connective tissue and smooth [[muscle]] parts are derived from [[mesoderm]].<ref name=Langman2019 />

After the third month, urethra also contributes to the development of associated structures depending on the biological sex of the embryo. In the male, the epithelium multiples to form the [[prostate]]. In the female, the upper part of the urethra forms the urethra and [[paraurethral gland]]s.<ref name=Langman2019 />

==Function==
===Urination===
{{See also|Urination}}
The urethra is the vessel through which urine exits the bladder. During urination, the urethra's smooth muscle relaxes as the bladder contracts to expel urine in a pressurized stream. Following this, the urethra re-establishes muscle tone by contracting the smooth muscle layer, and the bladder returns to a relaxed, quiescent state. Urethral smooth muscle cells are mechanically coupled to each other to coordinate mechanical force and electrical signaling in an organized, unitary fashion.<ref>{{cite journal | vauthors = Kyle BD | title = Ion Channels of the Mammalian Urethra | journal = Channels | volume = 8 | issue = 5 | pages = 393–401 | date = Aug 2014 | pmid = 25483582 | doi = 10.4161/19336950.2014.954224 | pmc=4594508}}</ref>

===Ejaculation===
The male urethra is the conduit for [[semen]] during [[orgasm]].<ref name="Wake1992"/> Urine is removed before ejaculation by [[pre-ejaculate]] fluid &ndash; called Cowper's fluid &ndash; from the bulbourethral gland.<ref>{{cite journal |last1=Killick |first1=Stephen R. |last2=Leary |first2=Christine |last3=Trussell |first3=James |last4=Guthrie |first4=Katherine A. |title=Sperm content of pre-ejaculatory fluid |journal=Human Fertility |date=15 December 2010 |volume=14 |issue=1 |pages=48–52 |doi=10.3109/14647273.2010.520798 |pmid=21155689 |pmc=3564677 }}</ref><ref name="chughtai">{{Cite journal|vauthors=Chughtai B, Sawas A, O'Malley RL, Naik RR, Ali Khan S, Pentyala S |title=A neglected gland: a review of Cowper's gland |journal=Int. J. Androl. |volume=28 |issue=2 |pages=74–7 |date=April 2005 |pmid=15811067 |doi=10.1111/j.1365-2605.2005.00499.x |s2cid=32553227 |doi-access=free }}</ref>

==Clinical significance==
[[File:Urethral urothelial cell carcinoma.jpg|thumb|right|[[Micrograph]] of [[urethral cancer]] ([[urothelial cell carcinoma]]), a rare problem of the urethra.]]
Infection of the urethra is [[urethritis]], which often causes purulent urethral discharge.<ref name=Davidsons2018urethritis /> It is most often due to a [[sexually transmitted infection]] such as [[gonorrhoea]] or [[chlamydia]], and less commonly due to other bacteria such as [[ureaplasma]] or [[mycoplasma]]; [[trichomonas vaginalis]]; or the viruses [[herpes simplex virus]] and [[adenovirus]].<ref name=Davidsons2018urethritis /> Investigations such as a [[gram stain]] of the discharge might reveal the cause; [[nucleic acid testing]] based on the [[first void urine|first urine sample passed in a day]], or a swab of the urethra sent for [[bacterial culture and sensitivity]] may also be used.<ref name=Davidsons2018urethritis /> Treatment usually involves [[antibiotic]]s that treat both gonorrhoea and chlamydia, as these often occur together.<ref name=Davidsons2018urethritis /> A person being treated for urethritis should not have sex until the infection is treated, so that they do not spread the infection to others.<ref name=Davidsons2018urethritis /> Because of this spread, which may occur during an [[incubation period]] before a person gets symptoms, there is often [[contact tracing]] so that sexual partners of an affected person can be found and treatment offered.<ref name=Davidsons2018urethritis>{{cite book|title=Davidson's principles and practice of medicine|last1=Ralston |first1=Stuart H. |last2=Penman |first2=Ian D. |last3=Strachan |first3=Mark W. |last4=Hobson |first4=Richard P.|date=2018 |publisher=Elsevier |isbn=978-0-7020-7028-0 |edition=23rd|page=333|section=Urethral discharge}}</ref>

Cancer can also develop in the lining of the urethra.<ref name=Davidsons2018cancer>{{cite book|title=Davidson's principles and practice of medicine|last1=Ralston |first1=Stuart H. |last2=Penman |first2=Ian D. |last3=Strachan |first3=Mark W. |last4=Hobson |first4=Richard P.|date=2018 |publisher=Elsevier |isbn=978-0-7020-7028-0 |edition=23rd|pages=435–6|section=Urothelial tumours}}</ref> When cancer is present, the most common symptom in an affected person is [[haematuria|blood in the urine]]; a physical [[medical examination]] may be otherwise normal, except in late disease.<ref name=Davidsons2018cancer /> [[Urethral cancer|Cancer of the urethra]] is most often due to cancer of the cells lining the urethra, called [[transitional cell carcinoma]], although it can more rarely occur as a [[squamous cell carcinoma]] if the type of cells lining the urethra have changed, such as due to a chronic [[schistosomiasis]] infection.<ref name=Davidsons2018cancer /> Investigations performed usually include collecting a sample of urine for an inspection for malignant cells under a microscope, called [[cytology]], as well as examination with a flexible camera through the urethra, called [[urethroscopy]]. If a malignancy is found, a [[biopsy]] will be taken, and a [[CT scan]] will be performed of other body parts (a [[Full-body CT scan|CT scan of the chest, abdomen and pelvis]]) to look for additional {{wt|en|metastatic}} lesions.<ref name=Davidsons2018cancer /> After the cancer is [[tumour staging|staged]], treatment may involve [[chemotherapy]].{{uncited|date=July 2020}}

===Injury===
Passage of [[kidney stone]]s through the urethra can be painful. Damage to the urethra by kidney stones, chronic infection, cancer, or catheterisation can cause narrowing, called a [[urethral stricture]].<ref>{{cite web | title = Urethral stricture | publisher = Mayo Clinic | date = 12 December 2018 | url = https://www.mayoclinic.org/diseases-conditions/urethral-stricture/symptoms-causes/syc-20362330 | access-date = 15 May 2020}}</ref> A [[retrograde urethrogram]] in which dye is injected into the urethra can reveal the location and structure of the narrowing.<ref name=Maciejewski2015>{{Cite journal|last1=Maciejewski|first1=Conrad|last2=Rourke|first2=Keith|date=2015-12-02|title=Imaging of urethral stricture disease|url=http://tau.amegroups.com/article/view/5675|journal=Translational Andrology and Urology|language=en|volume=4|issue=1|pages=2–9|doi=10.3978/j.issn.2223-4683.2015.02.03|pmid=26816803|pmc=4708283|issn=2223-4691}}</ref> Other forms of imaging such as [[ultrasound]], [[computed tomography]] and [[magnetic resonance imaging]] may also provide further details.<ref name=Maciejewski2015 />

Injuries to the urethra (e.g., from a [[pelvic fracture]]<ref name=Stein2015>{{cite journal|vauthors=Stein DM, Santucci RA |title=An update on urotrauma|journal=Current Opinion in Urology|volume=25|issue=4|pages=323–30|date=July 2015|pmid=26049876|doi=10.1097/MOU.0000000000000184|s2cid=26994715}}</ref>)

[[Urethral foreign body|Foreign bodies in the urethra]] are uncommon, but there have been medical case reports of self-inflicted injuries, a result of insertion of foreign bodies into the urethra such as an electrical wire.<ref>{{cite journal |doi=10.1186/1752-1947-3-49 |title=Electrical wire as a foreign body in a male urethra: a case report |year=2009 |last1=Stravodimos |first1=Konstantinos G |last2=Koritsiadis |first2=Georgios |last3=Koutalellis |first3=Georgios |journal=Journal of Medical Case Reports |volume=3 |article-number=49 |pmid=19192284 |pmc=2649937 |doi-access=free }}</ref>

===Other===
[[Hypospadias]] and [[epispadias]] are abnormal developments of the male urethra where the [[urinary meatus|meatus]] is not at the [[Anatomical terms of location#Proximal and distal|distal]] end of the penis (it occurs lower than normal with hypospadias, and higher with epispadias). In a severe [[chordee]], the urethra can develop between the penis and the scrotum.

===Catheterisation===
A tube called a [[catheter]] can be inserted through the urethra to drain urine from the bladder, called an [[indwelling urinary catheter]]; or, to bypass the urethra, a catheter may be directly inserted through the abdominal wall into the bladder, called a [[suprapubic catheter]].<ref name=NHS2020/> This may be to relieve or bypass an obstruction, to monitor [[urine output|how much urine someone produces]], or because a person has difficulty urinating, for example due to a [[neurological]] cause such as [[multiple sclerosis]].<ref name=NHS2020/> Complications that are associated with catheter insertion can include [[catheter-associated infection]]s, injury to the urethra or nearby structures, or pain.<ref name="NHS2020">{{cite web |title=Urinary catheters - NHS |url=https://www.nhs.uk/conditions/urinary-catheters/ |website=nhs.uk |access-date=2 July 2020 |language=en |date=26 February 2020}}</ref>

==Other animals==

In all [[mammal]]s, with the exception of [[monotreme]]s, and in both sexes, the urethra serves primarily to drain and excrete urine, which in mammals, collects in the urinary bladder and is released from there into the urethra. In addition, the closing mechanisms of the urethra, together with [[antibody|immunoglobulins]], largely prevent germs from penetrating the inside of the body.<ref>{{cite book|last=Wilson|first=Michaeltitle=Microbial Inhabitants of Humans: Their Ecology and Role in Health and Disease | title=Microbial Inhabitants of Humans: Their Ecology and Role in Health and Disease |publisher=Cambridge University Press |year=2005 |isbn=978-0-521-84158-0 |page=195|url=https://books.google.com/books?id=q9Qx9oRKO_kC}}</ref> In [[marsupial]]s, the female's urethra empties into the [[Urogenital sinus#Other animals|urogenital sinus]].<ref name="Tyndale-BiscoeRenfree1987">{{cite book|author1=Hugh Tyndale-Biscoe|author2=Marilyn Renfree|title=Reproductive Physiology of Marsupials|url=https://books.google.com/books?id=HpjovN0vXW4C&q=%22urogenital+sinus%22+urethra+marsupial&pg=PA172|date=30 January 1987|publisher=Cambridge University Press|isbn=978-0-521-33792-2|pages=172–}}</ref>

==History==
The word "urethra" comes from the [[Ancient Greek]] οὐρήθρα – ''ourḗthrā''. The stem "uro" relating to urination, with the structure described as early as the time of [[Hippocrates]].<ref name="Marx2010">{{cite journal |last1=Marx |first1=Franz Josef |last2=Karenberg |first2=Axel |title=Uro-words making history: Ureter and urethra |journal=The Prostate |date=2010 |volume=70 |issue=9 |pages=952–958 |doi=10.1002/pros.21129|pmid=20166127 |s2cid=32778667 |doi-access=free }}</ref> Confusingly however, at the time it was called "ureter". Thereafter, terms "ureter" and "urethra" were variably used to refer to each other thereafter for more than a millennium.<ref name=Marx2010 /> It was only in the 1550s that anatomists such as [[Bartolomeo Eustacchio]] and [[Jacques Dubois]] began to use the terms to specifically and consistently refer to what is in modern English called the ureter and the urethra.<ref name=Marx2010 /> Following this, in the 19th and 20th centuries, multiple terms relating to the structures such as [[urethritis]] and [[urethrography]], were coined.<ref name=Marx2010 />

Kidney stones have been identified and recorded about as long as written historical records exist.<ref name="Tefekli2013">{{cite journal |last1=Tefekli |first1=Ahmet |last2=Cezayirli |first2=Fatin |title=The History of Urinary Stones: In Parallel with Civilization |journal=The Scientific World Journal |date=2013 |volume=2013 |article-number=423964 |doi=10.1155/2013/423964 |pmid=24348156 |pmc=3856162 |doi-access=free }}</ref> The urinary tract as well as its function to drain urine from the kidneys, has been described by [[Galen]] in the second century AD.<ref name="Nahon2011">{{cite journal |last1=Nahon |first1=Irmina |last2=Waddington |first2=Gordon |last3=Dorey |first3=Grace |last4=Adams |first4=Roger |title=The History of Urologic Surgery: From Reeds to Robotics |journal=Urologic Nursing |date=2011 |volume=31 |issue=3 |pages=173–180 |doi=10.7257/1053-816X.2011.31.3.173 |pmid=21805756 }}</ref> Surgery to the urethra to remove kidney stones has been described since at least the first century AD by [[Aulus Cornelius Celsus]].<ref name="Nahon2011" />

==Additional images==
<gallery>
File:Prostatelead.jpg|Position of the urethra in males
File:Gray1155 a.png|Transverse section of the penis
File:Male urinary meatus.jpg|Male urethral opening on [[glans penis]]
File:Skenes gland.jpg|Female urethral opening within [[vulval vestibule]]
File:1116 Muscle of the Female Perineum.png|Muscles of the female perineum
File:Slide12BLA.JPG|Urethra. Deep dissection. Serial cross section.
File:Penis lateral cross section.jpg|Diagram which depicts the [[membranous urethra]] and the [[spongy urethra]] of a male
File:Female vaginal anatomy.jpg
</gallery>

==See also==
* [[Hypospadias|Perineal urethra]]
* [[Vulvovaginal health]]
* [[Urethral glands]]
* [[Urethral sponge]]
* Sexual stimulation: [[Urethral sounding]] and [[Urethral intercourse]]
* [[Urethrorrhagia]]
* [[Urethrotomy]]
* [[Urethrectomy]]
* [[Internal urethral orifice]]

==References==
{{Reflist}}

==External links==
* {{KansasHistology|epithel|epith07}} "Male Urethra"

{{Human systems and organs}}
{{Urinary system anatomy}}
{{Male reproductive system}}

{{Authority control}}

[[Category:Urethra| ]]
[[Category:Mammal reproductive system]]
[[Category:Urinary system]]
[[Category:Human reproductive system]]