Nipple !
The nipple is the raised tip at the centre of the areola where the milk ducts open; it delivers milk during breastfeeding.
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What it is
The raised tip of the breast, at about the 4th intercostal space, where the 15 to 20 lactiferous ducts open.
What it does
Delivers milk; smooth muscle makes it stand out with cold, touch or breastfeeding.
Key facts
- Where
- Centre of the areola, usually at the 4th intercostal space in the nulliparous woman (variable)
- Function
- 15–20 duct openings; smooth muscle erects it; dermatome T4
Relations
- Deep
- The lactiferous ducts converging on it and, just beneath the areola, their dilated lactiferous sinuses
- Contents
- Circular and longitudinal smooth muscle around the duct openings, dense sensory nerve endings and sebaceous glands; no fat and no hair
How to find it
In men, children and young women before pregnancy it usually sits in the 4th intercostal space, close to the midclavicular line. In adult women its position shifts with breast size, pregnancy and ptosis, so it is a poor landmark for counting ribs or placing drains.
Examination
- Inspection with the arms at the sides, then raised: retraction, deviation, flattening or an eczema-like change of the nipple itself point to a process beneath it
- Gentle pressure around the areola, clock position by clock position: the point that reproduces discharge from a single duct localizes the lesion (trigger point)
On imaging
Retroareolar ultrasound looks for dilated ducts or a small intraductal mass behind the nipple. In single-duct discharge, contrast injected into that duct (ductography or galactography) can show a filling defect; MRI is used when other tests are unclear.
Common problems
- Nipple discharge: bloody fluid from a single duct needs a check (papilloma, sometimes cancer).
- A nipple that newly turns inward (retraction) can be a sign of a cancer beneath it.
- Paget disease of the nipple: an eczema-like rash of the nipple linked to a cancer underneath.
- Cracked, painful nipples while breastfeeding.
How it is diagnosed
Examination, mammography and ultrasound; a biopsy of the nipple skin for Paget disease; a study of any discharge.
Treatment
- Breastfeeding problems: a better latch and nipple care.
- Paget disease and cancers: surgery with the cancer beneath; sometimes the nipple can be kept (nipple-sparing mastectomy).
Clinical notes
- Paget disease begins on the nipple and spreads to the areola; eczema usually begins on the areola and spares the nipple, a classic difference on inspection
- Bilateral milky discharge from several ducts outside lactation (galactorrhea) points to raised prolactin rather than a breast lesion
- Nipple-sparing mastectomy keeps the nipple skin when the tumour is far enough from it
- Cracked nipples during breastfeeding are a common entry point for the bacteria behind lactational mastitis
Anatomical variants
- Accessory nipples (polythelia) in about 1–4% of people of both sexes, usually along the milk line below the breast; often mistaken for a mole
- Congenitally inverted nipple, usually on both sides; absence of the nipple (athelia) is rare
Development
Forms on the mammary ridge (milk line), which runs from the axilla to the groin in the early embryo and regresses except over the chest; at birth the nipple is a shallow pit that rises later, and failure to rise leaves an inverted nipple.
Related conditions
Test yourself
Think of the answer, then tap the question to see it.
Which features make nipple discharge pathological rather than physiological?
Spontaneous, from one breast and one duct, bloody or clear; physiological discharge is usually from both breasts and several ducts, milky or greenish.
What does a recent, one-sided nipple retraction suggest?
A cancer pulling on the ducts; a nipple inverted since puberty that can be drawn out is usually a variant.
Which nerve gives the main sensation of the nipple and areola?
The 4th intercostal nerve (dermatome T4), a nerve at risk in breast reduction and augmentation.
How does Paget disease of the nipple differ from eczema on inspection?
Paget disease begins on the nipple and spreads to the areola; eczema usually begins on the areola and spares the nipple.
What does bilateral milky discharge from several ducts outside lactation point to?
Galactorrhea from raised prolactin, rather than a breast lesion.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- papilla mammaria TA2 7105
- Official Spanish (DeCS)
- Pezones DeCS D009558
- English (TA2)
- Nipple
- Also called
- nipples
Sources: Terminologia Anatomica (TA2); DeCS; Anatomy, Thorax, Breast; Anatomy, Thorax: Mammary Gland; Anatomy of the Human Body (20th ed.): Surface Anatomy of the Thorax (Lea & Febiger (Gray's Anatomy, 1918), 1918) · adapted, Public domain.
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Representative model, for educational purposes only.