Anatomy and Histology of the Breast Flashcards
What are mammary glands?
- modified sweat glands
- accessory to reproduction in women
- more developed in women
Where are the mammary glands of the breast located?
in subcutaneous tissue overlying pectoral muscles - pectoralis major & minor
What is the nipple?
at the greatest prominence
- 4th intercostal space (varies)
What is the areola?
- circular pigmented area surrounding the nipple (1-2cm)
- has sebaceous glands (glands of Montgomery) which secrete a protective lubricant
Describe the areola in pregnant women?
increases in size and gets darker with first pregnancy usually at 3 months
- never returns to original colour
The circular base (bed) of breast extends?
- Transversely - from lateral border of sternum to midaxillary line
- Vertically - from 2nd to 6th ribs
What is the axillary tail (of Spence)?
a small part of mammary gland that may extend along inferolateral edge of pectoralis major toward axilla to form axillary tail
What are the structures deep to the base of the breast?
- Deep pectoral fascia overlying pectoralis major (2/3)
- Fascia covering serratus anterior & external oblique (1/3)
- Retromammary space (bursa)
What is the retromammary space?
loose connective tissue space/plane between breast and deep pectoral fascia
- Has small amount of fat
- Allows some movement of breast on pectoral fascia
What are the suspensory ligaments of the breast (of Cooper)?
ligaments (retinacula cutis) firmly attaching breast to the dermis of overlying skin
What determines the size of the breast?
genetic, racial, diet
Describe the lobes of the mammary gland?
- Each mammary gland has 15-20 lobes
- Each lobe is drained by a lactiferous duct which opens on the nipple
Describe the course of the seminiferous ducts in the breast?
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
What are lactiferous sinuses?
dilations of ducts beneath areolar area
- act as reservoirs for milk
What is the arterial supply of the breast?
- Medial mammary branches
- perforating branches + anterior intercostal branches of internal thoracic artery - lateral thoracic + thoracoacromial arteries
- Branches of axillary artery - Posterior intercostal arteries
What is the venous drainage of the breast?
- Axillary vein
2. Internal thoracic vein
Why is lymph drainage important in the breast?
because of its role in metastasis
- spread of cancer cells
Lymph from the breast is drained to?
- Axillary lymph nodes - more than 75%
- Infraclavicular nodes
- Internal thoracic groups
Axillary nodes are arranged into what 5 groups?
- Pectoral nodes
- receive lymph from breast & ant chest wall - Lateral nodes
- receive most lymph from upper extremity - Subscapular nodes
- post body wall & scapular region - Central nodes
- pectoral, lat & subscapular nodes & pass it to - Apical nodes
- which then drain into infraclavicular & supraclavicular nodes and from them into subclavian trunk
Describe the drainage of the lateral half of the breast?
- drains mostly into pectoral nodes
- central & apical nodes via subclavian trunk (larger lymphatic ducts)
Describe the lymphatic drainage of the medial half of the breast?
flows to parasternal nodes inside chest cavity on either side of sternum
- bronchomediastinal trunks
Note: Cross connections occur - lead to metastasis
What is the nerve supply for the breast?
Anterior and lateral cutaneous branches of the 4th through 6th intercostal nerves
Describe the histology of a non-lactating mammary gland?
- branched alveolar glands
- modified apocrine sweat glands (few end pieces when inactive)
- adipocytes
Describe the histology of lactating mammary glands?
- myoepithelial cells
- fibroblasts
- end pieces have simple cuboidal epithelium
- adipocytes
