Breast: Normal Anatomy Flashcards
What is the breast?
- Secondary sexual feature of females
- Rudimentary structure in males
- Source of nutrition for neonates
What is the association between the breast and malignancy?
Site of malignant change in as many as 1 in 10 women
What does breast size and shape depend on?
Genetic, racial and dietary factors
What are the general features of the breast?
- Modified and highly specialized sweat glands
- No special capsule or sheath
- Well developed in females
What is the surface markings of the breast?
- Extends from 2nd/3rd rib to 6th rib
- Extends from sternal edge to midaxillary lie
What is the axillary tail (of spence)/process?
A small part of the breast which may extends towards the axillary fossa
What is the function of the retomammary space (bursa)?
Helps some degree of movement
What does the breast lie on?
- 2/3rd of the breast rests on the pectoral fascia covering pectoralis major
- 1/3rd of the breast rests on the fascia covering serratus anterior
How does the breast attach to the dermis?
By the suspensory ligament of cooper which helps support the lobules of the gland
What is the nipple?
Prominence of the breast
What is the areola?
Pigmented area around the nipple
What is the basic structure of the breast?
- Each breast contains 15-20 lobules of glandular tissue (parenchyma)
- Each lobule is drained by a lactiferous duct – opens independently on the nipple
- Each duct has a dilated portion – lactiferous sinus
What are the features of the nipple?
- No fat or hair
- Contains collagenous dense connective tissue, elastic fibres and bands of smooth muscle
- The tips of the nipples are fissured with lactiferous ducts opening into them
- Position : variable or 4th intercostal space
What are the features of the areola?
- Skin covering the nipple and areola contains numerous sweat & sebaceous glands
- Enlarge during pregnancy
- Oily material secreted by the sebaceous gland provides a protective lubricant for nipple and areola
How is the breast divided for description of pathology?
Into 4 quadrants
- Superomedial quadrant
- Inferomedial quadrant
- Superolateral quadrant (axillary tail is an extension)
- Inferolateral quadrant
When does temporary enlargement of the male breast occur?
In the newborn and during puberty
What are the features of the male breast?
- Rudimentary throughout life
- Formed by small ducts without lobules or alveoli
- Little supporting fibroadipose tissue
How does the breast develop?
- Mammary crests or ridges appear during 4th week
- These crests extend from axillary region to inguinal region
- The crests usually disappear except in the pectoral region
- Primary mammary buds – Secondary buds – lactiferous ducts and their branches
Athelia
Absence of nipple
Polythelia
An extra nipple
Polymastia
An extra breast
Amastia
Absence of breast
Gynecomastia
- Postnatal development of rudimentary lactiferous ducts in males
- During puberty around 2/3rd of boys develop varying degrees of hyperplasia of the breasts
What is the blood supply to the breasts?
Supplied by Branches of axillary artery, internal thoracic, and some intercostal arteries -Thoraco acromial artery -Lateral thoracic artery -Internal mammary (thoracic) artery
What is the nerve supply to the breasts?
Anterior and lateral cutaneous branches of 4-6th intercostal nerves
- They convey sensory fibres to the skin of the breast
- They also carry sympathetic fibres to the blood vessels and to the smooth muscle around the nipple
Why is the lymphatic drainage of the breast of great clinical significance?
Metastatic dissemination occurs primarily by the lymphatic routes
What is the lymphatic drainage of the beast?
- Most lymph (more than 75%) from lateral quadrants – axillary lymph nodes
- Some lymph may drain directly to supraclavicular or inferior cervical nodes
- Lymph from medial quadrants – parasternal or to opposite breast
What is the sentinel node?
First draining node
How is the sentinel localised?
- A radiolabelled colloid is used to locate the sentinel node
- At the time of surgery, a vital blue dye is injected
- Combination of radioisotope and dye provides most accurate means of localizing the node
What is identification of the sentinel node used for?
Lymphatic mapping and staging of patients
What is the soft tissue of the breast made from?
Made up of lobes which contains a network of glandular tissue consisting of branching ducts and secretory lobules in a connective tissue stroma.
What is the terminal duct lobular unit?
Functional milk secretory component of the breast
Describe the connective tissue stroma which surrounds the lobules in the breast.
It is dense and fibrocollagenous
Describe the interlobular tissue of the breast?
Loose texture
What can be seen on histology of the breast?
- Extensive branching duct system
- Surrounded by dense fibrous interlobular tissue and adipose tissue
- Ducts and acini are lined by 2 layers of cells: luminal epithelial cells and myoepithelial cells
What age related changes occur in the breast prepuberty?
- Neonatal breast contain lactiferous ducts but no alveoli
- Until puberty, little branching of the ducts occurs
- Slight breast enlargement reflects the growth of fibrous stroma and fat
What age related changes occur in the breast during puberty?
- Branching of lactiferous ducts
- Solid, spheroidal masses of granular polyhedral cells (alveoli)
- Accumulation of lipids in the adipocytes
What age related changes occur in the breast post-menopausal?
- Progressive atrophy of lobules and ducts
- Fatty replacement of glandular tissue
What is colostrum?
Protein rich fluid, available for a few days after birth. It is rich in maternal antibodies
What can be seen on histology of a lactating breast?
- Acini distended with milk
- Thin septa between the lobules
- At higher magnification acini with eosinophilic material containing clear vacuoles can be seen?
What stimulates milk production?
- Suckling, neurohormonal reflex
- Prolactin and oxytocin
What diagnostic methods are used in diagnosing breast pathology?
- Imaging including mammography and ultrasound
- Fine needle aspiration cytology
- Core biopsy
How common is breast cancer?
- 20% of all cancers in women
- Commonest cause of death in women in 35-55 age group
- In UK, any woman has a 1in 9 chance of developing breast cancer
What are some signs of breast cancer?
- Skin dimpling
- Oedema of skin
- Abnormal contours
- Nipple retraction and deviation
Give examples of benign breast tumours.
- Fibroadenomas
- Duct papillomas
- Adenomas
- Connective tissue tumours
What are the features of Paget’s disease?
- Erosion of the nipple resembling eczema
- Associated with ductal or invasive carcinoma
