Anatomy of the Breast

Question 1

What marks the base of the breast?

Answer 1

Rib 2 - Rib 6 (midclavicular line)

Question 2

What muscles underlie the breast?

Answer 2

Pectoralis Major

Laterally: Serratus Anterior + External Oblique

Question 3

What subunits are the breast made of? How many of them are there?

Answer 3

Ductal Lobular Units - 15-20 of them

Question 4

How many milk ducts are there in the breast?

Answer 4

4-18

Question 5

What is interspersed between the ductal lobular units?

Answer 5

FAT

Question 6

What structures divide the breast?

Answer 6

Fibrous septae - Suspensory ligaments of Cooper

Question 7

What are the two views in a mammogram?

Answer 7

Cranio-Caudal

Medial-Lateral Oblique (MLO)

Question 8

Is the upper part of a cranio-caudal mammogram the lateral or medial side?

Answer 8

Lateral

Question 9

What can breast cancer cause that appears as white streaks following the ducts?

Answer 9

Microcalcification

Question 10

What happens if the tumour interferes with the suspensory ligaments of Cooper?

Answer 10

Tethering of the skin

Question 11

Describe the blood supply to the breast.

Answer 11

Rich blood supply with branches from:

Internal thoracic artery

Lateral thoracic artery

Thoraco-dorsal artery

Thoraco-acromial artery

Intercostal arteries

Question 12

What nerves are mainly involved in providing sensory innervation to the breast?

Answer 12

Anteromedial and anterolateral branches of intercostal nerves T3-T5

Question 13

What nerve supplies the nipple?

Answer 13

Lateral cutaneous branch of the intercostal nerve T4

Question 14

How are benign lumps different to breast cancer?

Answer 14

They are smooth and longer than they are tall in the longitudinal plane

Question 15

Where does the lymph from the superficial and deep parts of the breast initially drain to

Answer 15

Superficial - subareolar plexus

Deep - submammary plexus

Question 16

Where does it then drain to from here?

Answer 16

Axillary group of pectoral lymph nodes

Question 17

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?

Answer 17

Bigger blob is probably the site of injection of the dye