7. Anatomy of the breast Flashcards Preview

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Flashcards in 7. Anatomy of the breast Deck (29)
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1
Q

What is the breast comprised of?

A

Glandular, fat and fibrous tissue

2
Q

Describe embryology of the breast

A

Derived from precursor ectoderm cells during week 4
Form mammary bud by week 5
Background breast stroma develops throughout gestation
>12 weeks, secondary buds lengthen and branch forming a complex network of radially arranged breast ducts that connect the nipple with the mammary lobules

3
Q

Where does the breast extend from?

A

Between 2nd and 6th rib spaces, from caudal to cranial

From lateral border of sternum to mid-axillary line

4
Q

How are breasts split?

A

Into 4 quadrants

Upper/Lower and Inner/ Outer

5
Q

Where does the majority os tissue lie compared to the remaining breast?

A

Upper outer quadrant

6
Q

How many ductal lobular units are in the breast? Where do they drain?

A

15-20 ductal-lobular units

Each drains into a main duct

7
Q

What lies interspersed between ductal lobular units?

A

Fat

8
Q

What structures divide the ductal lobular units?

A

Fibrous septae that radiate from the centre outwards

9
Q

What holds the breast?

A

Suspensory ligaments of Cooper (Coopers ligaments)

10
Q

How many milk ducts are there in the breast?

A

4-18

11
Q

Describe the blood supply to the breast

A
Branches of the:
Lateral thoracic artery
Internal thoracic artery
Thoracoacrominal artery
Thoracodorsal artery
Intercostal arteries
12
Q

What are the 3 principle groups of veins draining the breast?

A

Perforating branches of the internal mammary vein
Tributaries of the axillary vein
Perforating branches of the posterior intercostal veins

13
Q

Describe the main innervation to the breast

A

Anterolateral and anteromedial branches of thoracic intercostal nerves T3-T6.
Also innervation from the supraclavicular nerves to the upper and lateral parts of the breast.

14
Q

Describe innervation to the nipple

A

Dominant supply from the lateral cutaneous branch of T4.

15
Q

Where does the predominant lymphatic supply come from?

A

The axila

16
Q

What are the 5 groups of axillary lymph nodes?

A
Humeral
Subscapular
Pectoral
Central
Apical
17
Q

Describe % of drainage of the breast

A

75% of breast drains to lymphatics in axilla

25% of breast drains to lymphatics in Internal Mammary nodes

18
Q

Level 1 lymph nodes in pyramidal space

A

Lateral to pec minor

19
Q

Level 2 lymph nodes in pyramidal space

A

Posterior to pec minor

20
Q

Level 3 lymph nodes in pyramidal space

A

Medial to pec minor

21
Q

Lymphatic drainage of breast and axilla

A

Pyramidal compartment, tightly invested between the upper extremity and thoracic wall, 4 boundaries:
Medially: Serratus Anterior
Laterally: Intertubercular groove of humerus
Anteriorly: Pectoralis Major and Minor
Posteriorly: Teres Major, Subscapularis + Latissimus Dorsi

22
Q

Why do surgeons have to be careful when extracting lymph nodes?

A

Long thoracic nerve: damage results in winging of scapula
Thoraco-dorsal pedicle nerve: damage results in reduced power when lifting arm above head
Intercostal brachial nerves: Damage results in loss of sensation to upper inner aspect of arm

23
Q

Sentinel node biopsy

A

Mapping procedure.

Remove first 2-4 lymph nodes that drain breast cancer to the axilla.

24
Q

Breast cancer lymphoedema

A

Puffy swollen arm, debilitating

Occurs 2-3 years after lymphatics have been removed in surgery.

25
Q

Lymphoedema

A

Abnormal, generalized or regional accumulation of protein rich interstitial fluid
Oedema formation and change in tissue architecture
Reduction in lymphatic transport capacity from arm with an increase in lymphatic load

26
Q

Risk factors for lymphoedema

A
Axillary surgery
Radiotherapy
Chemotherapy
High BMI
Infection/ trauma
27
Q

Strategies to reduce lymphoedema

A

Less axillary surgery
Axillary reverse mapping (ARM)
LYMPHA

28
Q

Axillary reverse mapping

A

Discriminate lymphatics that drain the arm from the lymphatics that drain the breast
Aims to identify and preserve nodes and/or lymphatics draining from the arm during ALND, thereby minimizing arm lymphedema

29
Q

Congenital abnormalities affecting breast

A
Underdevelopment/ absence of 1 breast (may coexist with muscle/ribcage anomaly) = Poland syndrome 
Accessory nipples (polythelia) 
Absent nipples (athelia)
Accessory breast tissue
Tubular breast defomity