Urinary meatus

Urinary meatus
	Urinary meatus in the penis
Details
Identifiers
Latin	Orificium urethrae externum
FMA	19650
	Anatomical terminology

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 males and in females 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.

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 (0.98 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]

In other mammals

Unlike most other mammals, female spotted hyenas have a urinary meatus that is located on the clitoral glans.[3][4]

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

Notes

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

References

Sorokan SK, Finlay JC, Jefferies A. Newborn male circumcision. Paediatr Child Health. 2015;20(6):311–15. doi:10.1093/pch/20.6.311. PMID 26435672. PMC 4578472.
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.
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.
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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[1] Meatus refers to a tubular opening or passage in the body. From Latin meātus: a course, passing.

[CPS-2] Sorokan SK, Finlay JC, Jefferies A. Newborn male circumcision. Paediatr Child Health. 2015;20(6):311–15. doi:10.1093/pch/20.6.311. PMID 26435672. PMC 4578472.

[3] 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.

[4] 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.

[5] 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.