Normal Anatomy of the Breast Flashcards
What factors influence breast size and shape?
Genetic
Racial
Dietary
Extent of breast location on ribs
2nd/3rd rib to the 6th rib
Transverse location of the breast
Sternal edge to the mid axillary line
What does the breast lie on?
Deep pectoral fascia
What is the axillary tail (of spence) or process?
When a small part of the breast tissue extends towards the axillary fossa
What does 2/3rds of the breast rest on?
Pectoral fascia covering the pectoralis major
What does 1/3rd of the breast lie on?
The fascia covering the serratus anterior
How is the breast firmly attached to the dermis?
By the suspensory ligament of cooper - helps to support the lobules of the gland
What is the nipple?
The prominence of the breast
What is the areola?
The pigmented area around the nipple
How many lobules of glandular tissue (parenchyma) does each breast contain?
15-20
What is the functional unit of the breast?
Lobules of glandular tissue
How is each lobule drained?
By lactiferous duct - opens independently to the nipple
Function of the lactiferous sinus
Dilated position of each duct which, when breastfeeding starts, the milk is transferred from the alveoli into the sinuses and so a small amount is stored in the sinus, so the baby will get milk more easily
Position of the nipple
Variable of the 4th intercostal space
What does the nipple contain?
Collagenous dense connective tissue
Elastic fibres
Bands of smooth muscle
What does the nipple NOT have?
Fat
Hair
What does the areola contain?
Numerous sweat glands
Numerous sebaceous glands
Does the areola enlarge during pregnancy?
Yes
Function of the sebaceous gland of the areola
Oily material is secreted which provides a protective lubricant for the nipple and the areola
4 quadrants of the breast
Superomedial quadrant
Inferomedial quadrant
Superolateral quadrant (axillary tail extension of breast tissue in this quadrant)
Inferolateral quadrant
Male breast contains
Small ducts without lobules or alveoli
Little supporting adipose tissue
When does the male breast have temporary enlargement?
Newborn
During puberty
Development stages of the breast
- Mammary crests or ridges appear during the 4th week
- These crests usually disappear except in the pectoral region
- Primary mammary buds -> secondary mammary buds -> lactiferous ducts and their branches
Gynaecomastia definition
Post natal development of rudimentary lactiferous ducts in males
Polymastia definition
An extra breast
Polythelia definition
An extra nipple
Athelia definition
Absence of a nipple
Amastia definition
Absence of a breast
Breast blood supply
Branches of the axillary artery, internal thoracic Artery and some intercostal arteries
- thoraco-acromial artery
- lateral thoracic artery
- internal mammary (thoracic) artery
Nerve supply to the breast
Anterior and lateral cutaneous branches of the 4th-6th intercostal nerves
What do the nerves of the breast supply?
Sensory fibres to the skin of the breast
Sympathetic fibres to the blood vessels and to the smooth muscle around the nipple
Do breast lymphatics contain valves?
No
Clinical significance of breast lymphatic drainage
Metastatic dissemination occurs primarily by lymphatic routes
Spread of infection
Where does most of the lymph (>75%) from the lateral quadrants end up?
In the axillary nodes
Possible lymphatic drainage of the breast to…..
Axillary nodes
Supraclavicular nodes
Inferior cervical nodes
From medial quadrants - parasternal or opposite breast
What lymph node has a role in biopsies for breast cancer?
Sentinel node
What is the significance of the sentinel node
It is the first draining node
What is the functioning milk secretory component of the breast?
The terminal duct lobular unit
What is the breast soft tissue made up from?
Lobes which contain a network of glandular tissue consisting of branching ducts and secretory lobules in a connective tissue stroma
Lobular vs intralobular tissue
Lobular tissue = connective tissue stroma that surrounds the lobules is dense and fibrocollagenous
Intralobular tissue = loose texture
Branching duct system of the breast is surround by two types of tissue
- dense fibrous interlobular tissue
2. Adipose tissue
Ducts and acini of the breast are lined by two layers of cells
- luminal epithelial cells
2. myoepithelial cells
Changes to the breast pre-puberty
Neonatal breast contains lactiferous ducts but no alveoli
Until puberty, little branching of the ducts occurs
Slight breast enlargement reflects the growth of fibrous stoma and fat
Changes to the breast during puberty
Branching of lactiferous ducts
Solid, spheroidal masses of glandular polyhedral cells/alveoli
Accumulation of lipids in the adipocytes
Changes to the breast post-menopause
Progressive atrophy of lobules and ducts
Fatty replacement of glandular tissue
Histology of the breast during pregnancy shows….
Colostrum - protein rich fluid available a few days after birth
What is colostrum rich in?
Maternal antibodies
Histology of lactating breast shows…..
Acini distended with milk
Thin septa between lobules
At high magnification: acini with eosinophilic material containing clear vacuoles
Milk production; suckling-neurohormonal reflex -prolactin and oxytocin
Diagnostic methods in breast pathology
Mammography
USS
FNAC
Core biopsy
Warning signs of breast cancer on the breast
Skin dimpling
Abnormal contours
Edema of skin (peau d’orange sign)
nipple retraction and deviation
Pathology of carcinoma in situ of the breast
Cluster of malignant epithelial cells invade into the normal stroma
Chance of a woman developing breast cancer
1 in 9/10
Benign breast tumours include
Fibroadenoma
Duct papilloma
Adenoma
Connective tissue tumours
Definition of Pagets Disease of the nipple
Erosion of the nipple resembling ezcema
What is pagents disease of the nipple associated with?
Ductal or invasive carcinoma
