Anatomy and Histology of the Breast

Question 1

What are mammary glands?

Answer 1

• modified sweat glands
• accessory to reproduction in women
• more developed in women

Question 2

Where are the mammary glands of the breast located?

Answer 2

in subcutaneous tissue overlying pectoral muscles - pectoralis major & minor

Question 3

What is the nipple?

Answer 3

at the greatest prominence

- 4th intercostal space (varies)

Question 4

What is the areola?

Answer 4

• circular pigmented area surrounding the nipple (1-2cm)

- has sebaceous glands (glands of Montgomery) which secrete a protective lubricant

Question 5

Describe the areola in pregnant women?

Answer 5

increases in size and gets darker with first pregnancy usually at 3 months
- never returns to original colour

Question 6

The circular base (bed) of breast extends?

Answer 6

1. Transversely - from lateral border of sternum to midaxillary line
2. Vertically - from 2nd to 6th ribs

Question 7

What is the axillary tail (of Spence)?

Answer 7

a small part of mammary gland that may extend along inferolateral edge of pectoralis major toward axilla to form axillary tail

Question 8

What are the structures deep to the base of the breast?

Answer 8

1. Deep pectoral fascia overlying pectoralis major (2/3)
2. Fascia covering serratus anterior & external oblique (1/3)
3. Retromammary space (bursa)

Question 9

What is the retromammary space?

Answer 9

loose connective tissue space/plane between breast and deep pectoral fascia

• Has small amount of fat
• Allows some movement of breast on pectoral fascia

Question 10

What are the suspensory ligaments of the breast (of Cooper)?

Answer 10

ligaments (retinacula cutis) firmly attaching breast to the dermis of overlying skin

Question 11

What determines the size of the breast?

Answer 11

genetic, racial, diet

Question 12

Describe the lobes of the mammary gland?

Answer 12

• Each mammary gland has 15-20 lobes

- Each lobe is drained by a lactiferous duct which opens on the nipple

Question 13

Describe the course of the seminiferous ducts in the breast?

Answer 13

at the base of the nipple ducts narrow down, change direction from horizontal to vertical and run to summit of nipple
- terminal lactiferous ducts are larger near the central end of each lobe and converge towards nipple

Question 14

What are lactiferous sinuses?

Answer 14

dilations of ducts beneath areolar area

- act as reservoirs for milk

Question 15

What is the arterial supply of the breast?

Answer 15

1. Medial mammary branches
   - perforating branches + anterior intercostal branches of internal thoracic artery
2. lateral thoracic + thoracoacromial arteries
   - Branches of axillary artery
3. Posterior intercostal arteries

Question 16

What is the venous drainage of the breast?

Answer 16

1. Axillary vein

2. Internal thoracic vein

Question 17

Why is lymph drainage important in the breast?

Answer 17

because of its role in metastasis

- spread of cancer cells

Question 18

Lymph from the breast is drained to?

Answer 18

1. Axillary lymph nodes - more than 75%
2. Infraclavicular nodes
3. Internal thoracic groups

Question 19

Axillary nodes are arranged into what 5 groups?

Answer 19

1. Pectoral nodes
   - receive lymph from breast & ant chest wall
2. Lateral nodes
   - receive most lymph from upper extremity
3. Subscapular nodes
   - post body wall & scapular region
4. Central nodes
   - pectoral, lat & subscapular nodes & pass it to
5. Apical nodes
   - which then drain into infraclavicular & supraclavicular nodes and from them into subclavian trunk

Question 20

Describe the drainage of the lateral half of the breast?

Answer 20

• drains mostly into pectoral nodes

- central & apical nodes via subclavian trunk (larger lymphatic ducts)

Question 21

Describe the lymphatic drainage of the medial half of the breast?

Answer 21

flows to parasternal nodes inside chest cavity on either side of sternum
- bronchomediastinal trunks
Note: Cross connections occur - lead to metastasis

Question 22

What is the nerve supply for the breast?

Answer 22

Anterior and lateral cutaneous branches of the 4th through 6th intercostal nerves

Question 23

Describe the histology of a non-lactating mammary gland?

Answer 23

• branched alveolar glands
• modified apocrine sweat glands (few end pieces when inactive)
• adipocytes

Question 24

Describe the histology of lactating mammary glands?

Answer 24

• myoepithelial cells
• fibroblasts
• end pieces have simple cuboidal epithelium
• adipocytes

Question 25

Describe the secretion mechanism of lactation in mammary glands?

Answer 25

1. apocrine - lipid in milk

2. merocrine - protein

Question 25

Describe the secretion mechanism of lactation in mammary glands?

Answer 25

1. apocrine - lipid in milk

2. merocrine - protein

Question 26

What is metastasis?

Answer 26

spread of cancer cells - breast cancer

Question 27

What is a masectomy?

Answer 27

excision of breast - be mindful of the long thoracic nerve

Question 28

What is a lumpectomy?

Answer 28

only tumour & surrounding tissues are removed

Question 29

What is a mammography?

Answer 29

radiographic examination of breasts

Question 30

What is important to take note of in breast surgery during removal of axillary lymph nodes?

Answer 30

conservation of nerves is paramount

- Long thoracic nerve is at risk of damage as it crosses thoracic wall from brachial plexus to supply serratus anterior

Question 31

Damage to the long thoracic nerve may cause?

Answer 31

1. Paralysis of muscle
2. Winging of scapula, demonstrated by pushing the affected arm against a wall
   - patient has difficulty in raising her arm above the head & pushing