Breast Anatomy

Question 1

What is the breast

Answer 1

Modified sweat gland between subcutaneous fat, pectoralis muscle and serratus anterior

Consists of fat, fibrous tissue and glandular tissue.

From the lateral sternal border to mid axillary line, from 2nd to 6th rib.

Has an axillary tail which pierces deep fascia and enters axilla

Question 2

What is the glandular tissue of the breast?

Answer 2

15-20 lobules of tissue that drain into a lactiferous duct which converges towards the nipple. Areola is lubricated by glands of montogomery

Question 3

What is the suspensory ligament

Answer 3

Firbous septa running from subcutaneous tissue to fascia of chest wall, dividing breast lobules into segments

Question 4

What is the vascular supply of the breast

Answer 4

Arterial supply by:
Medial - internal thoracic artery (from subclavian)

Lateral
1. Lateral thoracic and thoracoacromial branches (from axillary)

2. Mammary branch of anterior intercostal artery (from thoracic aorta)
3. Lateral mammary of posterior intercostal artery

Venous drainage by internal thoracic vein, axillary vein, lateral thoracic vein and intercostal veins

Question 5

What is the innervation of the breast?

Answer 5

Intercostal nerve 2-6

Question 6

What is the lymphatic drainage of the breast?

Answer 6

75% to axillary lymph nodes

Medial drained by internal thoracic lymph nodes

Inter pectoral nodes (rotter’s nodes)

Drains into axillary, interior deep cervical and infraclavicular nodes

Question 7

How are the axillary lymph nodes divided surgically?

Answer 7

Level 1 - lateral to the pec minor

Level 2 - behind the pec minor and below axillary vein

Level 3 - medial to pec minor, up the axillary

Question 8

What is the important muscles associated with the breast

Answer 8

Pec major
Pec minor
Serratus anterior
Rectus abdominis 
External oblique muscles

Question 9

What are the important nerves associated with the breast

Answer 9

1. Median pectoral nerve (pec maj+min)
2. Lateral pectoral nerve (pec maj)
3. Long thoracic nerve (serratus)
4. Thoracodorsal nerve (lat dorsi)
5. Intercostobrachial nerve (from IC nerve 2) - sensation of medial arm and axilla

Question 10

What are the borders of the axilla?

Answer 10

Pec major anteriorly

Subscapularis posteriorly

Intertubucular sulcus laterally

Serratus anterior medially