Normal Breast Anatomy Lecture Flashcards
What is the main function of the breasts?
Secondary sexual feature
Source of nutrition for neonates
What are the general features of the breasts?
Modified and highly specialised sweat glands
No special capsule or sheath
Present in both genders
Well developed in females
Breast size and shape results from genetic, racial and dietary factors
What is the extent of the breasts both vertically and transversely?
Vertically - 2nd/3rd to 6th ribs
Transversely - Sternal edge to midaxillary line
What is the function of the retromammary bursa?
Helps some degree of movement of the breast
What is the axillary tail/process?
A small part of the breast that may extend to the axillary fossa
What does 2/3rds of the breast rest upon?
The pectoral fascia which covers the pectoralis major
What does 1/3rd of the breast rest upon?
The fascia covering the serratus anterior
How is the breast attached to the dermis?
Suspensory ligament of cooper which helps to support the lobules of the gland
What is the nipple?
The prominence of the breast
What is the areola?
The pigmented area surrounding the nipple
How many lobules of glandular tissue (parenchyma) does each breast contain?
15-20
How is each lobule drained?
Each lobule has a lactiferous duct which opens independently on the nipple
What is the dilated portion of the lactiferous duct called?
The lactiferous sinus
What are the 4 breast quadrants?
Superolateral quadrant
Superomedial quadrant
Inferolateral quadrant
Inferomedial quadrant
What is the axillary tail an extension of?
The superolateral quadrant
What are the characteristics of the male breast?
Rudimentary throughout life
Formed by small ducts without lobules or alveoli
Little supporting fibroadipose tissue
Temporary enlargement in newborn and during puberty
Explain the early development of the breast?
Mammary crests appear during 4th week
Crests extend from the axillary region to the inguinal region
The crests usually disappear except in the pectoral region
Primary mammary buds -> Secondary buds -> Lactiferous ducts and their branches
What is gynaecomastia?
Postnatal development of rudimentary lactiferous ducts in males
During midpuberty about 2/3rd of boys develop varying degrees of hyperplasia of the breasts
What is aphelia?
Absence of the nipple
What is amastia?
Absence of the breast
What is polymastia?
An extra breast
What is polythelia?
An extra nipple
What supplies blood to the breasts?
Branches of the axillary artery, internal thoracic and some intercostal arteries
Thoraco-acromial artery
Lateral thoracic artery
Internal mammary (thoracic) artery
What nerves supply the breast?
Anterior and lateral cutaneous branches 4-6th intercostal nerves
Convey sensory fibres to the skin of the breast
Also carry sympathetic fibres to the blood vessels and to the smooth muscle around the nipple
What is the clinical significance of the lymphatic drainage of the breast?
Great clinical significance because metastatic dissemination occurs primarily by the lymphatic routes
Breast lymphatics branch extensively and do not contain valves
Which lymph nodes drains more than 75% of the lymphatic fluid from the lateral quadrants of the breast?
Axillary lymph nodes
Where does the other lymphatic fluid drain to from the breast?
Supraclavicular or inferior cervical nodes
Where does the lymph from the medial quadrants of the breast drain?
Parasternal lymph nodes or to other breast
What is the role of the sentinel node biopsy?
Lymphatic mapping and staging of patients
What is used to locate the sentinel node?
A radiolabelled colloid and dye
What makes up the soft tissue of the breast?
Lobes containing a network of glandular tissue consisting of branching ducts and secretory lobules in a connective tissue stroma
What is function of the terminal duct lobular unit?
It is the functional milk secretory component of the breast
What type of connective tissue is the stroma that surrounds the lobules?
Dense and fibrocartilagenous
What is the texture of interlobular tissue?
Loose (it’s lit)
What are the histological characteristics of breast tissue?
Extensive branching duct system surrounded by dense fibrous interlobular tissue and adipose
Ducts and acini cells are lined by two layers of cells - luminal epithelial cells and myoepithelial cells
What changes happen to the breasts before puberty?
The neonatal breast contains lactiferous ducts but no alveoli
Until puberty little branching of the ducts occur
Slight breast enlargement reflects the growth of fibrous stroma and fat
What changes happen to the breasts during puberty?
Branching of the lactiferous ducts
Solid, spheroidal masses of granular polyhedral cells
Accumulation of lipids in the adipocytes
What changes happen to the breasts post-menopausally?
Progressive atrophy of lobules and ducts
Fatty replacement of glandular tissue
What histological characteristics are evident in breast tissue during pregnancy?
Enlarged lobules
Acini are dilated
Epithelium vary from cuboidal to low columnar
What is colostrum?
Protein rich fluid available a few days after birth - rich in maternal antibodies
What are the histological characteristics in breast tissue during lactation?
Acini are distended with milk
Thin septa are visible between lobules
At higher magnification acini can be seen with eosinophilic material containing clear vacuoles
Milk production happens in response to suckling which causes a neurohormonal reflex
What diagnostic methods can be used to examine the breasts?
Imaging - mammography, ultrasound
Fine needle aspiration cytology
Core biopsy
What are the signs of breast cancer that would be picked up on inspection of the breast?
Skin dimpling
Abnormal contours
Oedema of the skin
Nipple retraction
