Week 17 - Breast & Axilla

Question 1

The majority of the arterial supply to the breast is from branches of which two major arteries?

• a) Brachial artery and subclavian artery
• b) Internal thoracic artery and subclavian artery
• c) Internal thoracic artery and axillary artery
• d) Axillary artery and external carotid artery
• e) Brachial artery and posterior intercostal arteries

Answer 1

= c) Internal thoracic artery and axillary artery

Blood supply to Breast

1. From the axillary artery, principally via its lateral thoracic and acromiothoracic branches.
2. From the internal thoracic (hence its former name – the internal
   mammary artery) via its perforating branches; these pierce the 1st–4th intercostal spaces, then traverse pectoralis major to reach the
   breast along its medial edge. The 1st and 2nd perforators are the largest
   of these branches.
3. From the intercostal arteries via their lateral perforating branches; a relatively unimportant source.

The venous drainage is to the corresponding veins.

Question 2

Breast cancer is most commonly found in which area of the breast?

• a) Inferolateral quadrant
• b) Superolateral quadrant
• c) Inferomedial quadrant
• d) Superomedial quadrant
• e) Nipple and areola

Answer 2

Breast cancer is most commonly found in which area of the breast?

• a) Inferolateral quadrant
• b) Superolateral quadrant
• c) Inferomedial quadrant
• d) Superomedial quadrant
• e) Nipple and areola

Question 3

Name one muscle which forms the anterior axillary fold, and one major muscle that contributes to the posterior axillary fold.

Answer 3

anterior axillary fold = pec major & posterior axillary fold = latissimus dorsi & teres major

Borders of Axilla

• Apex – also known as the axillary inlet, it is formed by lateral border of the first rib, superior border of scapula, and the posterior border of the clavicle.
• Lateral wall – formed by intertubercular groove of the humerus.
• Medial wall – consists of the serratus anterior and the thoracic wall (ribs and intercostal muscles).
• Anterior wall – contains the pectoralis major and the underlying pectoralis minor and the subclavius muscles.
• Posterior wall – formed by the subscapularis, teres major and latissimus dorsi.

Question 4

The majority of the lymphatic drainage of the breast is to the axillary lymph nodes. List the five main groups of axillary lymph nodes.

Answer 4

1. Pectoral (anterior) - 3-5 nodes located in the medial wall of the axilla. They receive lymph primarily from the anterior thoracic wall & MOST OF BREAST
2. Subscapular (posterior) – 6-7 nodes, located along the posterior axillary fold and subscapular blood vessels. They receive lymph from the posterior thoracic wall and scapular region.
3. Humeral (lateral) – 4-6 nodes, located in the lateral wall of the axilla, posterior to the axillary vein. They receive most of the lymph drained from the upper limb.
4. Central – 3-4 large nodes, located near the base of the axilla (deep to pectoralis minor, close to the 2nd part of the axillary artery). They receive lymph via efferent vessels from the pectoral, subscapular and humeral axillary lymph node groups.
5. Apical – Located in the apex of the axilla, close to the axillary vein and 1st part of the axillary artery. They receive lymph from efferent vessels of the central axillary lymph nodes, therefore from all axillary lymph node groups. The apical axillary nodes also receive lymph from those lymphatic vessels accompanying the cephalic vein.

Question 5

Behind the breast is a layer of loose connective tissue termed the retromammary space. This potential space is found between which two layers?

• a) Posterior capsule and pectoral fascia
• b) Pectoralis fascia and pectoral major
• c) Posterior pectoral fascia and external intercostal muscles
• d) Innermost intercostal muscle and the parietal pleura
• e) Subclavius and pectoralis major

Answer 5

Retromammary space is between = a) posterior capsule & pectoral fascia