Flashcards in The Breast Deck (15):
What is the breast?
- Modified apocrine sweat gland.
- Part of the reproductive system: responds to sexual stimulation and to feed babies.
How do breasts develop?
1. Breast buds appear in both sexes in 6th - 9th months of foetal life.
2. At puberty, female breasts develop under influence of oestrogen and progesterone.
3. Final maturation during 1st pregnancy: mammary glands branch out and expand in response to progesterone and prolactin.
4. Regression following menopause.
Where are breasts located?
- Overlie pectoralis major muscles on left and right sides.
- From 2nd-6th ribs.
- From sternal edge to anterior axillary line.
What are breasts supported by?
Cooper's suspensory ligaments
What is breast tissue made up of?
1. Mostly of adipose tissue (supports glandular structures)
2. Mammary glands
- 15-20 lobes encased in a network of myoepithelial cells (contract and squeeze down on glands to excrete milk)
- milk drained towards nipple via lactiferous ducts
- expelled through nipple pores
What are the functions of areolae?
1. Contain areolar glands which secrete lipoid fluid - moisturises nipple during breastfeeding.
2. Darkened areolae provide target for baby to aim for.
Describe the blood supply to the breast.
1. Internal mammary arteries (derived from internal thoracic artery) - predominant blood supply.
2. External mammary arteries (lateral thoracic and thoracoaromial) and posterior intercostal arteries - further blood supply.
3. Axillary vein - venous drainage of breast.
What is lactation?
Process where milk is made and ejected from the mammary glands inside the female breasts.
How is lactation activated?
1. Baby starts to suckle - activates nipple mechanoreceptors - signalling up spinal cord to hypothalamus.
2. Hypothalamus releases:
i) Activatory signals to oxytocin neurons in posterior pituitary - oxytocin production.
ii) Inhibitory signals to PIH (prolactin inhibitory hormone) in anterior pituitary - prolactin production.
- Cascade stimulated by the sound of any babies' cry.
What are the effects of prolactin and oxytocin?
- Prolactin: stimulates mammary gland to produce milk.
- Oxytocin: stimulates myoepithelial cells surrounding glands.
What is accessory breast tissue?
- Relatively common congenital condition: abnormal accessory breast tissue is seen in addition of normal breast tissue.
- Can present as a mass anywhere along the course of the embryologic mammary streak (axilla to inguinal region).
What is Poland syndrome?
Rare birth defect characterised by:
- underdevelopment/absence of chest muscle (pectoralis) on 1 side of the body
- webbing of the fingers (cutaneous syndactyly) of ipsilateral hand
What is the most common cancer in women in the UK?
- Breast cancer
- 1/8 women
- >40,000 cases/year
- >10,000 deaths/year
Which factors increase the risk of breast cancer?
- family history
- personal history of breast cancer
- high socioeconomic class