Urinary meatus

The urinary meatus,[lower-alpha 1] (/miːˈeɪtəs/, mee-AY-təs) also known as the external urethral orifice, is the opening of the urethra. It is the point where urine exits the urethra in both sexes and where semen exits the urethra in males. The meatus has varying degrees of sensitivity to touch. The meatus is located on the glans of the penis or in the vulval vestibule.

Urinary meatus
Urinary meatus in the penis
Details
Identifiers
LatinOrificium urethrae externum
FMA19650
Anatomical terminology

In human males
Drawing of the male internal sexual anatomy

The male external urethral orifice is the external opening or urinary meatus, normally located at the tip of the glans penis, at its junction with the frenular delta. It presents as a vertical slit, possibly bounded on either side by two small labia-like projections, and continues longitudinally along the front aspect of the glans, which facilitates the flow of urine micturition. In some cases, the opening may be more rounded. This can occur naturally or may also occur as a side effect of excessive skin removal during circumcision. The meatus is a sensitive part of the male reproductive system.

Meatal stenosis is a late complication of circumcision, which occurs in about 10–20 percent of newborn circumcised boys after the loss of the protection of the foreskin.[1]

In human females
Lateral anatomy view of the female reproductive system

The female external urethral orifice is the external opening of the urethra, from which urine is ejected during urination. It is located about 2.5 cm (1 in) behind the clitoris and immediately in front of the vagina in the vulval vestibule. It usually assumes the form of a short, sagittal cleft with slightly raised margins. To its left and right are the openings of the Skene's glands.

Some evidence exists to suggest that the clitoral-urinary meatus distance (CUMD) in human females relates to the ease with which the female may achieve orgasm through penetrative sex. Orgasm from penetration alone is observed to be more likely as CUMD decreases.[2]

Evidence also suggests that decreased distance from the vaginal opening to the urethral meatus is associated with recurrent post-coital urinary tract infections. [3] Surgical repositioning of the distal urethra to prevent recurrent post-coital urinary tract infections has been employed with some success by Russian physicians.[4]

In other mammals

Unlike most other mammals (including human), female spotted hyenas have a urinary meatus that is located on the clitoral glans.[5][6]

Clinical significance

Congenital disorders of the meatus, in the male, include epispadias (the misplacement to the upper aspect) and hypospadias (the misplacement to the underside of the penis). A congenital misshaping can result in its narrowing (meatal stenosis), causing a partial or total urinary blockage or the bifurcation of the urinary stream. A urethral blockage can also be caused by foreign material, kidney stones, or bladder stones (lithiasis).

Additional images
  • The male urinary meatus viewed externally
  • The female urinary meatus viewed externally, with surrounding structures labelled

See also
Wikimedia Commons has media related to Meatus urethrae, male.

Notes
  1. Meatus refers to a tubular opening or passage in the body. From Latin meātus: a course, passing.

References
  1. Sorokan SK, Finlay JC, Jefferies A (2015). "Newborn male circumcision". Paediatr Child Health. 20 (6): 311–15. doi:10.1093/pch/20.6.311. PMC 4578472. PMID 26435672.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  2. Wallen, Kim; Lloyd, Elisabeth A. (2017-03-13). "Female Sexual Arousal: Genital Anatomy and Orgasm in Intercourse". Hormones and Behavior. 59 (5): 780–792. doi:10.1016/j.yhbeh.2010.12.004. ISSN 0018-506X. PMC 3894744. PMID 21195073.
  3. Gyftopoulos, K; Matkaris, M (2019). "Clinical implications of the anatomical position of the urethra meatus in women with recurrent post-coital cystitis: a case-control study". Int Urogynecol J. 30 (8): 1351–1357. doi:10.1007/s00192-018-3710-7. PMID 29968091. S2CID 49559889.
  4. Sumerova, Natalia; Pushkar, Dmitry (2011). "Transposition of Distal Urethra in Female Patients with Recurrent Lower UTI Associated with Sexual Intercourse". Clinical Management of Complicated Urinary Tract Infection. doi:10.5772/22301. ISBN 978-953-307-393-4. S2CID 44044908.
  5. Cunha, Gerald R.; et al. (2014). "Development of the external genitalia: perspectives from the spotted hyena (Crocuta crocuta)". Differentiation. 87 (1): 4–22. doi:10.1016/j.diff.2013.12.003. PMC 4069199. PMID 24582573.
  6. Drea, C. M.; et al. (2002). "Exposure to naturally circulating androgens during foetal life incurs direct reproductive costs in female spotted hyenas, but is prerequisite for male mating". Proceedings of the Royal Society of London B: Biological Sciences. 269 (1504): 1981–1987. doi:10.1098/rspb.2002.2109. PMC 1691120. PMID 12396496.
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