Breast Anatomy Flashcards
When do the mammary crests/milk lines appear on the foetus?
4th week
What type of gland is the breast?
Exocrine gland.
Modified sweat gland.
Tubulo-acinar gland.
How many breast lobes are on each breast?
15-25
How many women see malignant changes in the breast?
1 in 10.
What is the function of breasts?
Female - secondary sexual feature.
Male - present in rudimentary form
Neonates - source of nutrition
What does the lactiferous duct become?
Closer to the nipple it dilates to become the lactiferous sinus.
What determines breast size and shape?
Genetics
Diet
racial
Which ribs do the breasts overlie?
2nd or 3rd rib - 6th rib. (costal cartilages)
What are the lateral borders of the breasts
Medial - sternal edge.
Lateral - mid-axillary line
Axillary tail - extends up into the axillary fossa.
Which muscles does the breast overlie?
- pectoralis major
- pectoralis minor
- serratus anterior
Which glands produce milk?
Mammary glands.
Which muscle does the nipple possess?
Smooth muscle fibres.
Which glands are present in the areola?
Sebaceous glands - these enlarge during pregnancy.
What do the sebaceous glands produce?
An oily substance
- it sterilises the breast
- it tells the neonate where the nipple is located
What is in the mammary gland?
Lots of alveoli, drained by a SINGLE lactiferous duct
What are the name of the suspensory ligaments?
Ligaments of Cooper. These often change in malignancy, giving the breast an altered appearance.
Where do the suspensory ligaments attach to?
The pectorals fascia (flat sheet of connective tissue) - which overlies the pectoralis major muscle.
What is the arterial supply to the breast?
Medial - internal thoracic/mammary artery.
Lateral - lateral thoracic and thoracoacromial arteries, lateral mammary branches, mammary branch
Which lymph nodes drain the breast?
- axillary (75%), (lateral quadrants)
- parasternal (20%)
- posterior intercostal (5%)
- can also drain into opposite breast or directly to supraclavicular or inferior cervical nodes
Where does the lymph from skin of the breast go?
- skin - axillary lymph nodes
- nipple and areola - subareolar lymphatic plexus
What is the nerve supply fo the breast?
anterior and lateral cutaneous branches of the 4th to 6th intercostal nerves.
^ This contains sensory and autonomic nerves.
Which hormones control milk production and secretion?
- oxytocin (posterior)
- prolactin (anterior)
from pituitary gland.
Which Fascia does the breast lie on?
2/3rds lies on the pectoralis major fascia.
1/3rds lies on the serratus anterior fascia.
What are the main features of the nipple?
- 4th intercostal space (variable)
- lactiferous ducts open into them
- connective tissue, elastic fibres and smooth muscle
What are the main features of the areola?
- contains lots of sweat and sebaceous glands
- enlarge/pigment during pregnancy and lactation
- oily substance provides protective lubricant
What causes erection of the nipple?
Contraction of the band of smooth muscle surrounding the nipple
What are the 4 quadrants of the breast?
- superiomedial
- inferiomedial
- inferiolateral
- superiolateral (+ axillary tail)
What is the male breast anatomy?
Has small ducts but NO LOBULES OR ALVEOLI.
What happens to male breasts during puberty?
2/3rds of males develop varying hyperplasia of the breasts
What is an extra breast called?
Polymastia
What is an extra nipple called?
Polythelia
What causes an extra breast or nipple?
persistence of the breast one
What is absence of the nipple called?
Athelia
What is absence of the breast called?
Amastia
What is the venous drainage of the breast?
Medial - internal thoracic vein
Lateral - axillary vein
Where does the sympathetic nerve innervation for the breasts blood vessels come from?
The cervical sympathetic chain.
What is the first draining lymph node in the breast?
The sentinel node - this is tested during pathology. If the node isn’t involved, the tumour hasn’t spread.
What is the excretory part of the breast?
Duct system.
What is the secretory part of the breast?
Acini.
What type of cells surround the ducts and acini?
Epithelial and myoepithelial cells (they squeeze the secretion that’s in the acini by contracting).
What are the milk parts of the breast called?
Lobes, acini/alveoli, lactiferous ducts, lactiferous sinus.
What happens to the breast during puberty?
Before - lactiferous ducts but no alveoli/acini.
Puberty - branching of lactiferous ducts, alveoli, lipids and adipocytes.
What happens to the breast post menopausal?
- Progressive atrophy of lobules and ducts
- fatty replacement of glandular tissue
In histology, how can you tell the difference between the fat and acinar cells?
Both white:
- fat - not lined by epithelium
- acini - lined by epithelium, can also see the secretions in the acini.
What is colostrum?
protein rich fluid available a few days after birth - maternal antibodies, laxatives and low fat.
