L6: Axilla and breast

Question 1

axilla

Answer 1

• three sided pyramidal space between upper arm and thorax
• it is located between skin of the armpit and upper ribcage
• continuous with posterior triangle of neck via cervico-axillary canal
• cervico-axillary canal allows nerves and blood vessels to pass between neck and upper limb

Question 2

axilla - boundaries:
apex, medial wall, lateral wall, base

Answer 2

apex: lies between clavicle, scapula and lateral border of 1st rib
Medial wall: ribs 1-4 and intercostal muscles, slips serratus anterior
Lateral wall: intertubercular sulcus of humerus, anterior and posterior axillary folds converge at the intertubercular sulcus
Base: formed by skin and fascia

Question 3

axilla boundaries: anterior axillary fold, posterior axillary fold

Answer 3

anterior axillary fold: pectoralis major (mostly), small contributions from pectoralis minor and subclavius muscle

posterior axillary fold: subscapularis (superior), teres major (middle), latissimus dorsi (inferior)

Question 4

contents of axilla

Answer 4

• axillary artery + its 6 branches
• axillary vein and its tributaries
• brachial plexus
• lateral branches of intercostal nerves
• 5 groups of lymph nodes > important for lymphatic drainage of the breast

Question 5

breast

Answer 5

• accessory organ of female reproductive system - modified exocrine gland
• secretes milk for an infant - lactation
• 1 in 9 women diagnosed with breast cancer during their life
• ~1% of breast cancer diagnosis are men

Question 6

breast position

Answer 6

• located on anterior thoracic wall
• along midclavicular line, overlies ribs 2-6
• overlies pectoral muscles and serratus anterior
• extends from lateral border of sternum to the mid-axillary line
• usually descried in 4 quadrants
• portion extending into axillary fossa known as axillary process or tail (of spence)

Question 7

retromammary space

Answer 7

retromammary space separates breast and pectoral muscles / serratus anterior

this is a potential space, and is utilised in reconstructive / cosmetic surgery

Question 8

breast deep structure

Answer 8

fat lobules
suspensory ligaments > aka ligaments of cooper
lactation apparatus:
-mammary alveoli
-mammary lobules
-lactiferous ducts
-lactiferous sinus
-nipple-areolar complex

Question 9

suspensory ligaments

Answer 9

aka ligaments of cooper

extend from deep fascia to skin around nipple

skin dimpling can be indicative of breast cancer due to shortening of ligaments due to tumour mass

Question 10

innervation of breast

Answer 10

Anterior and lateral cutaneous branches of intercostal nerves 2-6
Pass through deep pectoral fascia to reach the breast
Carry sensory and sympathetic fibres
-Sensory fibres carry sensory signals back to spinal cord and brain
-Sympathetic fibres carry signals from brain and spinal cord to control blood vessels and smooth muscle in overlying skin and nippl

Question 11

breast arterial supply

Answer 11

superiorly: branches of the thoracoacromial artery

inferolaterally: branches of the intercostal arteries

medially: branches of the internal thoracic artery

laterally: branches of the lateral thoracic artery

Question 12

breast - venous drainage

Answer 12

Venous drainage corresponds to arterial supply and mostly drains to the axillary vein
but also…
Inferolaterally to intercostal veins 2-4
Medially to internal thoracic vein
Laterally to lateral thoracic vein

Question 13

breast changes during lactation

Answer 13

breast growth driven by hormones:
-oestrogen
-progesterone
-prolactin
-lactogen

Lactation:
-prolactin released from anterior pituitary gland
-alveoli within mammary lobules produce
-milk travels via lactiferous ducts to lactiferous sinus for storage
-feeding or extraction devices harvest milk stored in the lactiferous sinuses

Question 14

lymphatic system

Answer 14

Second circulatory system
Reabsorbs fluid and electrolytes from extracellular system and contains white blood cells (lymphocytes)
Fluid known as chyle (milky)
Consists of lymph nodes connected by lymph ducts
Generally, follows venous system and returns chyle to venous system for recirculation

Question 15

lymphatic drainage of the axilla

Answer 15

Pectoral nodes drain superior ½ of anterior thorax
Subscapular nodes drain medial wall, posterior fold and axillary process of the breast
Humeralnodes drain the majority of the upper limb
Centralnodes drain pectoral, subscapular and humeral nodes
Apical nodes drain central nodes

Question 16

lymphatic drainage of the breast

Answer 16

~75% drains to the axillary lymph nodes
Majority of the rest drains medially to the parasternal lymph nodes
Small amount drains to deep cervical and supraclavicular or even abdominal lymph nodes

Question 17

breast cancer

Answer 17

diagnosis and staging by triple assessment
- clinical history and examination
- imaging e.g. mammography, CT/MRI
- biopsy

Question 18

breast cancer - management

Answer 18

Lumpectomy or Mastectomy?
*Lumpectomy = removal of suspicious lump
*Mastectomy = removal of breast

*Axillary clearance: removal of lymph nodes from axilla, to prevent lymphogenous spread of cancer
Chemotherapy and/or radiotherapy?Reconstructive surgery?

Question 19

potential consequences of axillary clearance

Answer 19

*Lymphoedema of upper limb
*Upper limb lymph congestion as drainage via normal lymphatic channels interrupted.
*Long thoracic nerve involvement
*Winging of scapula

Question 20

prophylactic mastectomy

Answer 20

• genetic susceptibility to breast cancer [BRCA1 and BRCA2 gene mutations]
• patient may elect to have mastectomies to reduce chance of developing breast cancer

Question 21

p’eau d’orange

Answer 21

*Swelling (lymphodoema) within breast increases size of breast
*Cooper’s ligaments are tethered to skin, and tightening of these ligaments causes dimpling at each attachment site
*Clinically this appearance is known as Peau d’Orange.
*Causes include breast infection (mastitis), inflammatory breast cancer and more.