Anatomy of the breast Flashcards
what are breasts?
It is a modified apocrine sweat gland
what is the breast made of?
It is made of:
- fat
- glandular tissue
- fibrous tissue
What marks the base of the breast?
Rib 2 - Rib 6 (midclavicular line)
where does the breast parenchyma extend?
Extends in the anterior axillary fold as the axillary tail of spence.
What muscles underlie the breast?
Pectoralis Major
Laterally: Serratus Anterior + External Oblique
What subunits are the breast made of? How many of them are there?
Ductal Lobular Units - 15-20 of them, each draining into a main duct
How many milk ducts are there in the breast?
4-18
What is interspersed between the ductal lobular units?
FAT
What structures divide the breast?
Fibrous septae - Suspensory ligaments of Cooper
what supplies blood to the breasts?
Branches of the lateral thoracic artery, internal thoracic artery, thoracoacromial artery, thoracodorsal artery and intercostal arteries.
what supplies the breast skin?
The skin is supplied by the subdermal plexus which communicates with the deep parenchymal vessels.
what supplies the nipple-areola?
The nipple-areola receives a branch from the internal thoracic artery in most cases.
Is the upper part of a cranio-caudal mammogram the lateral or medial side?
Lateral
What can breast cancer cause that appears as white streaks following the ducts?
Microcalcification
What happens if the tumour interferes with the suspensory ligaments of Cooper?
Tethering of the skin
Describe the blood supply to the breast.
Rich blood supply with branches from: Internal thoracic artery Lateral thoracic artery Thoraco-dorsal artery Thoraco-acromial artery Intercostal arteries
What nerves are mainly involved in providing sensory innervation to the breast?
Anteromedial and anterolateral branches of intercostal nerves T3-T5
What nerve supplies the nipple?
Lateral cutaneous branch of the intercostal nerve T4
How are benign lumps different to breast cancer?
They are smooth and longer than they are tall in the longitudinal plane
Where does the lymph from the superficial and deep parts of the breast initially drain to?
Superficial - subareolar plexus
Deep - submammary plexus
Where does it then drain to from here?
Axillary group of pectoral lymph nodes
When using dye to identify the sentinal lymph node, two blobs can appear on the X ray. What is the large blob usually caused by?
Bigger blob is probably the site of injection of the dye
When using dye to identify the sentinal lymph node, two blobs can appear on the X ray. What is the large blob usually caused by?
Bigger blob is probably the site of injection of the dye
describe the 3 ways of the venous drainage breast?
3 principle groups of veins
- Perforating branches of the internal mammary vein
- Tributaries of the axillary vein
- Perforating branches of the posterior intercostal veins
where is the innervation of the nipple?
how is the breast innervated
Dominant supply from the lateral cutaneous banch of T4.
Principally through the lateral and anterior cutaneous branches of the 2nd through 6th intercostal nerves
what are the arrangments of the lymph nodes on the breast?
T1, T2, and T3.
what is the lymphatic drainage breast and the axilla. Medially Laterally Anteriorly Posteriorly
- Medially: Serratus Anterior over 1st 4 ribs
Laterally: Intertubercular groove of humerus & Biceps tendon, & Coracobrachialis
Anteriorly: Pectoralis Major & Minor - Posteriorly: Teres Major, Subscapularis + tendon Latissimus Dorsi
what is lymphoedema and what causes this and what does this cause?
- Removal of lymph nodes through surgeries
- 2-3 years after patients get lymphoedema
- Abnormal, generalized or regional accumulation of protein rich interstitial fluid
- Oedema formation and change in tissue architecture
- causes fat accumulation and scarring
What is axillary reverse mapping?
- way to prevent lymphodema of the hands
- Aims to identify and preserve nodes and/or lymphatics draining from the arm during ALND, thereby minimizing arm lymphedema
Reverse mapping – blue dye, radioisotope or ICG
congential abnormalities of the breast
Underdevelopment or absence of one breast (may coexist with muscle/ribcage anomaly) – *Poland syndrome
Accessory nipples (polythelia) absent nipples (athelia)
Accessory breast tissue
Tubular breast defomity
