Breast Anatomy

Question 1

What is the breast?

Answer 1

Modified apocrine sweat gland located in subcutaneous tissue overlying fascia of anterior thoracic wall muscles (pectoralis major and serratus anterior) and is composed of fat, fibrous and glandular tissues

Question 2

What factors affect the breasts characteristics?

Answer 2

Menstrual cycle/hormones
Age and sexual maturity
Inherited factors
Pregnancy
Lactation
Nutrition

Question 3

What is the characteristic of the breast that remains the same between individuals?

Answer 3

Point of contact with chest wall i.e. the position of the breast base which is:

• Superoinferior and extending from rib 2 to 6
• Mediolateral and extending from lateral sternal border to MAL
• Extending superolaterally into axilla to form axillary tail of Spence along pectoralis major inferior border

Question 4

Why can individuals develop polythelia/polymastia?

Answer 4

Breasts develop along the mammary ridge (milk line) from axilla to groin which is why pigs have nipples continuously through this line but in humans most should regress although when things go wrong supranumerary nipples (polythelia) or accessory breast tissue (polymastia) can develop along this line

Question 5

What is the nipple?

Answer 5

The area surrounded by the areolar which receives 15-20 lactiferous ducts

Question 6

What is the areolar?

Answer 6

Region of pigmented skin around the nipple that often darkens during and after pregnancy - sweat and sebaceous glands (Montgomery glands) open onto this lubricating the area by secreting an oily substance

Question 7

How is the breast supported?

Answer 7

By the fibrous suspensory Cooper ligaments sit within breast and attach to dermis - can be pulled on/shortened with a tumour so skin dimples

Question 8

What structure permits free movement of breast independent of pectoralis major?

Answer 8

Retromammary space that sits between breast tissue and pectoralis fascia filled with loose connective tissue and fat

Question 9

What does it indicate if the breast moves with the pectoralis muscle contraction? How would you test this?

Answer 9

Underlying pathology e.g. tumour fixating the breast tissue to the muscle - test by asking patient to place hand on hip and pushing/contracting

Question 10

What type of glands does the breast lobules contain?

Answer 10

Acinar branched glands (increases SA) which drain into common ducts

Question 11

What is the microstructure of the breast?

Answer 11

Lobules make up lobes. There is a collection of glandular secretory units/lobes packed in fat and connective tissue with about 15-20 in each breast as a separate entity called mammary lobes (secretions controlled by hormones) which drain into terminal lactiferous ducts and sinuses to come out of nipple.

Question 12

What is Paget’s disease of the breast/nipple?

Answer 12

Where breast cancer spreads along the duct system and out onto the nipple and surrounding skin (infections can spread this way too although irrelevant to this disease)

Question 13

What are the 2 main types of breast cancer?

Answer 13

Arise from:

1. Duct tissue
2. Lobular tissue

Question 14

What is the microstructure of actively lactating breasts?

Answer 14

There is a clear acinar arrangement of glandular tissue surrounded by myoepithelial cells which contract in response to oxytocin causing milk secretion into terminal lactiferous duct

Question 15

What pathology can occur in the glands of the breast?

Answer 15

Infection leading to mastitis or breast abscesses

Question 16

How does the microstructure of the breast change with age?

Answer 16

As a result of hormonal changes e.g. oestrogen, progesterone and prolactin over the lifetime:

• Young, non-pregnant and pre-menopausal women have a lot of fibrous connective tissue
• Pregnant women have a lot of glands
• Elderly post-menopausal women have a lot of adipose tissue

Question 17

How does medical imaging of the breast vary with age?

Answer 17

Medical imaging of the breast can be influenced by the relative proportions of tissue present so choice of imaging may change with age e.g. harder to find tumour in young women due to fibrous tissue but easier in elderly due to fat in mammagrams

Question 18

What is the innervation of the breast?

Answer 18

Intercostal nerves (T4-6)

Question 19

What are the different types of mastalgia that can occur?

Answer 19

Cyclical/non-cyclical (e.g. w/ menstrual cycle)

Non-breast origin e.g. skin (shingles for example), resp, cardiac, MSK

Question 20

What is the blood supply of the breast?

Answer 20

RICH & ANASTOMOTIC between:

1. Lateral mammary branches from lateral thoracic artery (joins axillary a.) and posterior intercostal arteries
2. Medial mammary branches from internal thoracic (joins subclavian a.)/anterior intercostal arteries

Question 21

What is the lymph drainage of the breast?

Answer 21

Medial breast: parasternal/internal thoracic lymph nodes that interconnect between sides (not usually palpable)

Lateral breast: anterior and central axillary lymph nodes (palpable)

Nipple, areolar and breast tissue (glandular aspects): parasternal AND axillary

Skin: axillary, infraclavicular and deep cervical nodes

Question 22

What are the other less common routes of lymphatic drainage from the breast?

Answer 22

Interpectoral (Rotter) 
Contralateral parasternal 
Contralateral breast
Subdiaphragmatic/hepatic
Inguinal

Question 23

What may be the result of axillary node sampling or clearance?

Answer 23

Sampling (removing a few nodes) and clearance (removing all lymph/tubes) may result in LYMPHOEDEMA because drainage of the upper limb is impaired - do not cannulate, take blood or take BP from that side if patient has had these procedures for this reason

Question 24

How should the breast be examined?

Answer 24

Get patient to lie flat so breast tissue spreads out thinly and ask patient to move arms around to exacerbate any differences in appearance, then lightly/deeply palpate the 4 quadrants of the breast examining the areolar and nipple too comparing sides against each other - if a lump is found, fully assess and describe it

Question 25

How can breast disease present?

Answer 25

Pain
Lump
Nipple discharge
Infection
Nipple inversion
Skin changes

Question 26

What is a fibroadenoma?

Answer 26

A tumour from fibrous and glandular tissue causing a discreet lump that moves around the breast when you touch it unlike other malignancies

Question 27

What types of breast tissue can pathology occur within?

Answer 27

Epithelial
Glandular
Connective
Fatty

Question 28

What observable changes can be seen with breast cancer?

Answer 28

Asymmetric/new onset nipple retraction
P’eau d’orange (due to blocked lymphatics leading to skin retractions)
Dimpling of skin
Nipple discharge/bleeding
Pagets disease of nipple/breast (looks like eczema around breast)
Inflammatory changes

Question 29

What is gynaecomastia?

Answer 29

Enlargement of male breast resulting from proliferation of glandular component as a result of drugs or diseases e.g. cancer due to oestrogen increase relative to androgens