Teats
| Nipple | |
|---|---|
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| Details | |
| Identifiers | |
| Latin | papilla mammaria |
| TA | A16.0.02.004 |
| FMA | 67771 |
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Anatomical terminology
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The nipple is a raised region of tissue on the surface of the breast from which milk leaves the breast through the lactiferous ducts. The milk can flow through the nipple passively or it can be ejected by smooth muscle contractions that occur along the ductal system. The nipple is surrounded by the areola which is often a darker color than the surrounding skin. It is often called a teat when referring to non-humans. Teat can also be used to describe the flexible mouthpiece of a baby bottle. In humans, nipples of both males and females can be stimulated as part of sexual arousal. In many cultures, human female nipples are sexualized, or "...regarded as sex objects and evaluated in terms of their physical characteristics and sexiness."
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. The nipple is also used an anatomical landmark. It marks the T4 (fourth thoracic vertebra) dermatome and rests over the approximate level of the diaphram.
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 mechanoreceptors. 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.
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