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Revision as of 14:26, 12 August 2017 view sourceBfpage (talk | contribs)Autopatrolled, Extended confirmed users, Pending changes reviewers, Rollbackers19,587 edits →Nipple stimulation: ..not so rare← Previous edit Revision as of 14:27, 12 August 2017 view source Bfpage (talk | contribs)Autopatrolled, Extended confirmed users, Pending changes reviewers, Rollbackers19,587 edits →Nipple stimulation: no need to cite the ref inline - that is the purpose of the reference section. This isn't MLANext edit →
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During breastfeeding, nipple stimulation by an infant will simulate the release of ] from the ]. Oxytocin is a hormone that increases during pregnancy and acts on the breast to help produce the ]. Oxytocin also causes uterine contractions postpartum when the infant begins to nurse and stimulates the nipple.<ref>{{cite web|url=https://www.womenshealth.gov/glossary/#o|title=Glossary - womenshealth.gov|website=womenshealth.gov|accessdate=12 August 2017}}{{PD-notice}}</ref> The strong uterine contractions that are caused by the stimulation of the mother's nipples help the uterus contract. These contractions are necessary to prevent ].<ref name=Abedi2016>{{cite journal|last1=Abedi|first1=P|last2=Jahanfar|first2=S|last3=Namvar|first3=F|last4=Lee|first4=J|title=Breastfeeding or nipple stimulation for reducing postpartum haemorrhage in the third stage of labour.|journal=The Cochrane database of systematic reviews|date=27 January 2016|volume=1|pages=CD010845|pmid=26816300|doi=10.1002/14651858.CD010845.pub2}}</ref> When the baby suckles or stimulates the nipple, oxytocin levels rise and small muscles in the breast contract and move the milk through the milk ducts. The result of nipple stimulation by the newborn helps to move out through the ducts and to the nipple. This contraction of milk is called the “let-down reflex.”<ref>https://www.womenshealth.gov/files/documents/your-guide-to-breastfeeding.pdf</ref> Latching on refers to the baby fastening onto the nipple to breastfeeding. A good attacment is when the bottom of the areola (the area around the nipple) is in the baby's mouth and the nipple is drawn back inside his or her mouth. A poor latch results in insuffienct nipple stimulation. The nipple is poorly stimulated when the baby latches on too close to the tip. This can cause cracked nipples and a reluctance to continue to breastfeed.<ref name = whgov>{{cite web|url=https://www.womenshealth.gov/itsonlynatural/overcoming-challenges/breastfeeding-checklist-how-to-get-good-latch.html|title=Breastfeeding checklist: How to get a good latch | publisher = WomensHealth.gov | accessdate=4 August 2017}}{{PD-notice}}</ref><ref name = whgov2>{{cite web|url=https://www.womenshealth.gov/itsonlynatural/overcoming-challenges/common-questions-about-breastfeeding-pain.html|title=Common questions about breastfeeding and pain | publisher = womenshealth.gov|accessdate=4 August 2017}}{{PD-notice}}</ref> After the birth of the infant, the milk supply increases due to increased stimulation of the nipple. If the baby increases nursing time at the nipple, the mammary glands respond to this stimulation by increasing milk production, During breastfeeding, nipple stimulation by an infant will simulate the release of ] from the ]. Oxytocin is a hormone that increases during pregnancy and acts on the breast to help produce the ]. Oxytocin also causes uterine contractions postpartum when the infant begins to nurse and stimulates the nipple.<ref>{{cite web|url=https://www.womenshealth.gov/glossary/#o|title=Glossary - womenshealth.gov|website=womenshealth.gov|accessdate=12 August 2017}}{{PD-notice}}</ref> The strong uterine contractions that are caused by the stimulation of the mother's nipples help the uterus contract. These contractions are necessary to prevent ].<ref name=Abedi2016>{{cite journal|last1=Abedi|first1=P|last2=Jahanfar|first2=S|last3=Namvar|first3=F|last4=Lee|first4=J|title=Breastfeeding or nipple stimulation for reducing postpartum haemorrhage in the third stage of labour.|journal=The Cochrane database of systematic reviews|date=27 January 2016|volume=1|pages=CD010845|pmid=26816300|doi=10.1002/14651858.CD010845.pub2}}</ref> When the baby suckles or stimulates the nipple, oxytocin levels rise and small muscles in the breast contract and move the milk through the milk ducts. The result of nipple stimulation by the newborn helps to move out through the ducts and to the nipple. This contraction of milk is called the “let-down reflex.”<ref>https://www.womenshealth.gov/files/documents/your-guide-to-breastfeeding.pdf</ref> Latching on refers to the baby fastening onto the nipple to breastfeeding. A good attacment is when the bottom of the areola (the area around the nipple) is in the baby's mouth and the nipple is drawn back inside his or her mouth. A poor latch results in insuffienct nipple stimulation. The nipple is poorly stimulated when the baby latches on too close to the tip. This can cause cracked nipples and a reluctance to continue to breastfeed.<ref name = whgov>{{cite web|url=https://www.womenshealth.gov/itsonlynatural/overcoming-challenges/breastfeeding-checklist-how-to-get-good-latch.html|title=Breastfeeding checklist: How to get a good latch | publisher = WomensHealth.gov | accessdate=4 August 2017}}{{PD-notice}}</ref><ref name = whgov2>{{cite web|url=https://www.womenshealth.gov/itsonlynatural/overcoming-challenges/common-questions-about-breastfeeding-pain.html|title=Common questions about breastfeeding and pain | publisher = womenshealth.gov|accessdate=4 August 2017}}{{PD-notice}}</ref> After the birth of the infant, the milk supply increases due to increased stimulation of the nipple. If the baby increases nursing time at the nipple, the mammary glands respond to this stimulation by increasing milk production,


Nipples can be sensitive to touch and can lead to ].<ref name="winkelmann">{{cite journal |title=The erogenous zones: their nerve supply and significance |author=Winkelmann RK |journal=Mayo Clin Proc |year=1959 |volume=34 |pages=39–47 |url=http://www.cirp.org/library/anatomy/winkelmann/ |issue=2}}</ref> The male and female nipple have a similar nerve supply, though nerve endings are closer together in men, whereas in a female nipple they are further apart.<ref name="sarhadi">{{cite journal |title=An anatomical study of the nerve supply of the breast, including the nipple and areola |author=Sarhadi NS |journal=British Journal of Plastic Surgery |year=1996 |volume=49 |pages=156–164 |url=http://www.sciencedirect.com/science/article/pii/S0007122696902180 |issue=3 |doi=10.1016/S0007-1226(96)90218-0 |pmid=8785595 |last2=Shaw Dunn |first2=J |last3=Lee |first3=FD |last4=Soutar |first4=DS}}</ref> Nipple stimulation can lead to an ]. Based on a 2011 Komisaruk et al. study, which indicates that sensation from the nipples travels to the same part of the brain as sensations from the vagina, clitoris and cervix, research suggests that the orgasms are genital orgasms caused by nipple stimulation and may be directly linked to the genital sensory cortex ("the genital area of the brain"). Nipple stimulation may trigger uterine contractions, which then produce a sensation in the genital area of the brain.<ref name="Smith">{{cite book|author=Merril D. Smith|title=Cultural Encyclopedia of the Breast|publisher=]|isbn=0759123322|page=71|date=2014|accessdate=August 12, 2017|url=https://books.google.com/books?id=qrCCBAAAQBAJ&pg=PA71}}</ref><ref name="Lehmiller">{{cite book|author=Justin J. Lehmiller|title=The Psychology of Human Sexuality|publisher=]|isbn=1118351320|page=120|date=2013|accessdate=August 12, 2017|url=https://books.google.com/books?id=pQRgAgAAQBAJ&pg=PT120}}</ref><ref name="Komisaruk">{{Cite journal|author=Komisaruk, B. R., Wise, N., Frangos, E., Liu, W.-C., Allen, K. and Brody, S. |title=Women's Clitoris, Vagina, and Cervix Mapped on the Sensory Cortex: fMRI Evidence |journal=] |year=2011|doi=10.1111/j.1743-6109.2011.02388.x|laysummary= http://www.cbsnews.com/news/surprise-finding-in-response-to-nipple-stimulation/ Surprise finding in response to nipple stimulation |laysource=]|laydate=August 5, 2011|volume=8|issue=10|pages=2822–30 |pmid=21797981 |pmc=3186818}}</ref> Nipples can be sensitive to touch and can lead to ].<ref name="winkelmann">{{cite journal |title=The erogenous zones: their nerve supply and significance |author=Winkelmann RK |journal=Mayo Clin Proc |year=1959 |volume=34 |pages=39–47 |url=http://www.cirp.org/library/anatomy/winkelmann/ |issue=2}}</ref> The male and female nipple have a similar nerve supply, though nerve endings are closer together in men, whereas in a female nipple they are further apart.<ref name="sarhadi">{{cite journal |title=An anatomical study of the nerve supply of the breast, including the nipple and areola |author=Sarhadi NS |journal=British Journal of Plastic Surgery |year=1996 |volume=49 |pages=156–164 |url=http://www.sciencedirect.com/science/article/pii/S0007122696902180 |issue=3 |doi=10.1016/S0007-1226(96)90218-0 |pmid=8785595 |last2=Shaw Dunn |first2=J |last3=Lee |first3=FD |last4=Soutar |first4=DS}}</ref> Nipple stimulation can lead to an ]. Sensation from the nipples travels to the same part of the brain as sensations from the vagina, clitoris and cervix, research suggests that the orgasms are genital orgasms caused by nipple stimulation and may be directly linked to the genital sensory cortex ("the genital area of the brain"). Nipple stimulation may trigger uterine contractions, which then produce a sensation in the genital area of the brain.<ref name="Smith">{{cite book|author=Merril D. Smith|title=Cultural Encyclopedia of the Breast|publisher=]|isbn=0759123322|page=71|date=2014|accessdate=August 12, 2017|url=https://books.google.com/books?id=qrCCBAAAQBAJ&pg=PA71}}</ref><ref name="Lehmiller">{{cite book|author=Justin J. Lehmiller|title=The Psychology of Human Sexuality|publisher=]|isbn=1118351320|page=120|date=2013|accessdate=August 12, 2017|url=https://books.google.com/books?id=pQRgAgAAQBAJ&pg=PT120}}</ref><ref name="Komisaruk">{{Cite journal|author=Komisaruk, B. R., Wise, N., Frangos, E., Liu, W.-C., Allen, K. and Brody, S. |title=Women's Clitoris, Vagina, and Cervix Mapped on the Sensory Cortex: fMRI Evidence |journal=] |year=2011|doi=10.1111/j.1743-6109.2011.02388.x|laysummary= http://www.cbsnews.com/news/surprise-finding-in-response-to-nipple-stimulation/ Surprise finding in response to nipple stimulation |laysource=]|laydate=August 5, 2011|volume=8|issue=10|pages=2822–30 |pmid=21797981 |pmc=3186818}}</ref>


==Nipple disorders== ==Nipple disorders==

Revision as of 14:27, 12 August 2017

This article is about the anatomical structure. For other uses, see Nipple (disambiguation).
Nipple
A nipple, areola and breast of a human female.
Details
Identifiers
Latinpapilla mammaria
MeSHD009558
TA98A16.0.02.004
TA27105
FMA67771
Anatomical terminology[edit on Wikidata]

The nipple is a protuberance that sits upon the surface of the breast from which the milk produced by the breast leaves the breast through the lactiferous ducts. The milk can flow through the nipple passively or it can be ejected by muscular contractions that occur along the ductal system. The nipple is surrounded by the areola which varies in pigmentation. It is often called a teat when referring to non-humans.The flexible mouthpiece of a baby bottle. In humans, nipples of both males and females be stimulated as part of sexual arrousal. In many cultures, human female nipples are sexualized.

Etymology

The word "nipple" most likely originates as a diminutive of neb, an Old English word meaning "beak", "nose", or "face", and which is of Germanic origin. The words "teat" and "tit" share a Germanic ancestor. The second of the two, tit, was inherited directly from Proto-Germanic, while the first entered English via Old French.

Anatomy

The breast: cross-section scheme of the mammary gland:
  1. Chest wall
  2. Pectoralis muscles
  3. Lobules
  4. Nipple
  5. Areola
  6. Milk duct
  7. Fatty tissue
  8. Skin

In the anatomy of mammals, a nipple, mammary papilla or teat is a small projection of skin containing the outlets for 15–20 lactiferous ducts arranged cylindrically around the tip. The skin of the nipple is rich in a supply of special nerves that are sensitive to certain stimuli: these are slowly-adapting and rapidly-adapting cutaneous mechanocepetors. Mechanoreceptors are identified respectively by Type I slowly-adapting with multiple Merkel corpuscle end-organs and Type II slowly-adapting with single Ruffini corpuscle end-organs, as well as Type I rapidly-adapting with multiple Meissner corpuscle end-organs and Type II rapidly-adapting with single Pacinian corpuscle end-organs.

The dominant innervation to the nipple is derived from the lateral cutaneous branches of fourth intercostal nerve. The physiological purpose of nipples is to deliver milk to the infant, produced in the female mammary glands during lactation. Marsupials and eutherian mammals typically have an even number of nipples arranged bilaterally, from as few as two to as many as 19.

In humans

Changes in size

The average projection and size of human female nipples is slightly more than 3/8 of an inch (10mm). This is equal to about five stacked American quarters. Pregnancy and nursing tend to increase nipple size, sometimes permanently. Pregnancy also deepens the pigmentation.

Nipple stimulation

Main article: Nipple stimulation

During breastfeeding, nipple stimulation by an infant will simulate the release of oxytocin from the hypothalmus. Oxytocin is a hormone that increases during pregnancy and acts on the breast to help produce the milk-ejection reflex. Oxytocin also causes uterine contractions postpartum when the infant begins to nurse and stimulates the nipple. The strong uterine contractions that are caused by the stimulation of the mother's nipples help the uterus contract. These contractions are necessary to prevent post-partum hemorrhage. When the baby suckles or stimulates the nipple, oxytocin levels rise and small muscles in the breast contract and move the milk through the milk ducts. The result of nipple stimulation by the newborn helps to move out through the ducts and to the nipple. This contraction of milk is called the “let-down reflex.” Latching on refers to the baby fastening onto the nipple to breastfeeding. A good attacment is when the bottom of the areola (the area around the nipple) is in the baby's mouth and the nipple is drawn back inside his or her mouth. A poor latch results in insuffienct nipple stimulation. The nipple is poorly stimulated when the baby latches on too close to the tip. This can cause cracked nipples and a reluctance to continue to breastfeed. After the birth of the infant, the milk supply increases due to increased stimulation of the nipple. If the baby increases nursing time at the nipple, the mammary glands respond to this stimulation by increasing milk production,

Nipples can be sensitive to touch and can lead to sexual arousal. The male and female nipple have a similar nerve supply, though nerve endings are closer together in men, whereas in a female nipple they are further apart. Nipple stimulation can lead to an orgasm. Sensation from the nipples travels to the same part of the brain as sensations from the vagina, clitoris and cervix, research suggests that the orgasms are genital orgasms caused by nipple stimulation and may be directly linked to the genital sensory cortex ("the genital area of the brain"). Nipple stimulation may trigger uterine contractions, which then produce a sensation in the genital area of the brain.

Nipple disorders

In male mammals

A human male nipple

Mammalian fetuses within the same species look the same, regardless of sex. In humans, this lasts for around 6 weeks, after which genetically-male fetuses begin producing male hormones such as testosterone. Usually, males' nipples do not change much past this point; however, some males develop a condition known as gynecomastia, in which the fatty tissue around and under the nipple develops into something similar to a female breast. This may happen whenever the testosterone level drops. Gynecomastia, although not as severe, may occur in pubescent boys undergoing physical changes due to the rapid and uncontrolled release of hormones, including estrogen. The heightened levels of estrogen in pubescent male bodies leads to the swelling of the nipple and surrounding tissue – this can often look similar to a female human nipple – and may cause slight discomfort. Thus, because the "female template" is the default for humans, the question is not why evolution has not selected against male nipples, but why it would be advantageous to select against male nipples to begin with:

The uncoupling of male and female traits occurs if there is selection for it: if the trait is important to the reproductive success of both males and females but the best or "optimal" trait is different for a male and a female. We would not expect such an uncoupling if the attribute is important in both sexes and the "optimal" value is similar in both sexes, nor would we expect uncoupling to evolve if the attribute is important to one sex but unimportant in the other. The latter is the case for nipples. Their advantage in females, in terms of reproductive success, is clear. But because the genetic "default" is for males and females to share characters, the presence of nipples in males is probably best explained as a genetic correlation that persists through lack of selection against them, rather than selection for them. Interestingly, though, it could be argued that the occurrence of problems associated with the male nipple, such as carcinoma, constitutes contemporary selection against them.

In a now-famous paper, Stephen Jay Gould and Richard C. Lewontin emphasize that we should not immediately assume that every trait has an adaptive explanation. Just as the spandrels of St. Mark's domed cathedral in Venice are simply an architectural consequence of the meeting of a vaulted ceiling with its supporting pillars, the presence of nipples in male mammals is a genetic architectural by-product of nipples in females. This idea implies men have nipples because females do.

See also

References

  1. https://www.tabers.com/tabersonline/view/Tabers-Dictionary/762857/1/nipple&ti=0
  2. Todd Beer (2015-05-12). "Social Construction of the Body: The Nipple". sociologytoolbox.com. Retrieved 2015-05-16.
  3. Harper, Douglas (2001–2010). "nipple". Online Etymological Dictionary. Retrieved 15 August 2011.
  4. Harper, Douglas (2001–2010). "teat". Online Etymological Dictionary. Retrieved 15 August 2011.
  5. Harper, Douglas (2001–2010). "tit (1)". Online Etymological Dictionary. Retrieved 15 August 2011.
  6. Grabb & Smith's Plastic Surgery 6th edition. Chapter 59 page 593
  7. "The Wonder of Milk". Earthlife.net. Retrieved 2013-05-09.
  8. M. Hussain, L. Rynn, C. Riordan and P. J. Regan, "Nipple-areola reconstruction: outcome assessment"; European Journal of Plastic Surgery, Vol. 26, Num. 7, December, 2003
  9. Dr. Ted Eisenberg and Joyce K. Eisenberg, ‘’The Scoop on Breasts: A Plastic Surgeon Busts the Myths,’’ Incompra Press, 2012, ISBN 978-0-9857249-3-1
  10. "Glossary - womenshealth.gov". womenshealth.gov. Retrieved 12 August 2017.Public Domain This article incorporates text from this source, which is in the public domain.
  11. Abedi, P; Jahanfar, S; Namvar, F; Lee, J (27 January 2016). "Breastfeeding or nipple stimulation for reducing postpartum haemorrhage in the third stage of labour". The Cochrane database of systematic reviews. 1: CD010845. doi:10.1002/14651858.CD010845.pub2. PMID 26816300.
  12. https://www.womenshealth.gov/files/documents/your-guide-to-breastfeeding.pdf
  13. "Breastfeeding checklist: How to get a good latch". WomensHealth.gov. Retrieved 4 August 2017.Public Domain This article incorporates text from this source, which is in the public domain.
  14. "Common questions about breastfeeding and pain". womenshealth.gov. Retrieved 4 August 2017.Public Domain This article incorporates text from this source, which is in the public domain.
  15. Winkelmann RK (1959). "The erogenous zones: their nerve supply and significance". Mayo Clin Proc. 34 (2): 39–47.
  16. Sarhadi NS; Shaw Dunn, J; Lee, FD; Soutar, DS (1996). "An anatomical study of the nerve supply of the breast, including the nipple and areola". British Journal of Plastic Surgery. 49 (3): 156–164. doi:10.1016/S0007-1226(96)90218-0. PMID 8785595.
  17. Merril D. Smith (2014). Cultural Encyclopedia of the Breast. Rowman & Littlefield. p. 71. ISBN 0759123322. Retrieved August 12, 2017.
  18. Justin J. Lehmiller (2013). The Psychology of Human Sexuality. John Wiley & Sons. p. 120. ISBN 1118351320. Retrieved August 12, 2017.
  19. Komisaruk, B. R., Wise, N., Frangos, E., Liu, W.-C., Allen, K. and Brody, S. (2011). "Women's Clitoris, Vagina, and Cervix Mapped on the Sensory Cortex: fMRI Evidence". The Journal of Sexual Medicine. 8 (10): 2822–30. doi:10.1111/j.1743-6109.2011.02388.x. PMC 3186818. PMID 21797981. {{cite journal}}: Unknown parameter |laydate= ignored (help); Unknown parameter |laysource= ignored (help); Unknown parameter |laysummary= ignored (help)CS1 maint: multiple names: authors list (link)
  20. Walker, Marsha (2011). Breastfeeding management for the clinician : using the evidence. Sudbury, Mass: Jones and Bartlett Publishers. p. 530. ISBN 9780763766511.
  21. "The Developing Embryo". Gender.org/Jed Bland. Retrieved August 3, 2011.
  22. Simons, Andrew M. "Why do men have nipples? Scientific American (September 17, 2003)
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