Anatomy And Physiology Of The Breast Flashcards
How many ribs does the breast occupy?
Extends from the second rib above to the sixth rib below
Where does the breast extend to laterally?
Mid-axillary line.
Medially the breast extends from the lateral edge of the body of the sternum, to the mid-axillary line laterally.
Where’s the tail of spence?
At the superolateral aspect of the breast, there is a projection of breast tissue towards the axilla along the lower border of pectoralis major, which is known as the axillary tail (or tail of Spence).
How many lobes are there in the breast?
There are between 15-20 lobes of the breast, each containing 20-40 lobules. Ducts extend from these to converge onto the nipple.
The lobes are arranged approximately radially but may be of varying size with some degree of intertwining of their branches.
What are Cooper’s ligaments?
Cooper’s ligaments are thin sheets of fascia that extend like a mesh through the breast parenchyma, attaching to the dermis and the superficial and deep fascial layers. They provide support to the breast.
What are the two basic functional parts of the breast?
All breasts are composed of two basic functional parts:
• the epithelial component of the breast is concerned with milk production, and consists of the lobules which make milk, and the ducts which carry the milk to the nipple
• all the other tissues that make up and support the breast, including fat and connective tissue
Which arteries supply the breast?
The breast is supplied by an anastomotic network formed from:
- Branches of the axillary artery.
- Perforating branches of intercostal arteries.
- Perforating branches of the internal mammary artery.
Which groups of lymph nodes drain the breast?
There are two main groups of lymph nodes which drain the breast - the axillary nodes and the internal mammary nodes.
Which lymph nodes drain most of the lymphatic fluid of the breast?
About 75% of the lymphatic drainage of the breast goes to the axillary nodes.
There are around 20-30 axillary nodes, which are anatomically subdivded into five groups, but for surgical and pathological purposes they are generally considered in terms of ‘levels’.
o Level 1: nodes inferior to pectoralis minor
o Level 2: nodes behind pectoralis minor
o Level 3: nodes above pectoralis minor
What is the TDLU?
Histologically, the terminal portion of the duct system is known as the terminal duct lobular unit (TDLU).
- The TDLU consists of a lobule (milk-producing gland) and its associated terminal duct. A lobule takes the form of a cluster of multiple blind-ending ductules surrounding by specialised connective tissue.
- Breast cancer is thought to originate in the TDLU.
What happens to the breast at puberty in women?
At puberty, under the influence of hormonal changes (predominantly oestrogen but also progesterone), proliferation and branching of the ductal system occurs together with the formation of solid masses of cells at the duct terminations, which are to become the future breast lobules.
When is the breast fully functional?
Fully functional development of the breast only occurs with the hormonal changes of pregnancy and lactation.
In the pregnant woman, ductal and lobular proliferation occur, with the glandular tissue occupying proportionally more of the breast.
Increased pigmentation of the nipple and areola also occur.
How is lactation established following birth?
If the baby suckles regularly.
Which two hormones control Lactation?
The hormonal regulation of lactation is complex, but two important hormones are prolactin, which is lactogenic, and oxytocin which is released in response to suckling.
Oxytocin causes contraction of the myoepithelial cells increasing the supply of milk, and also mediates the secretion of prolactin.
What happens to the breast after menopause?
After the menopause, there is atrophy of the glandular elements and a decrease in the amount of fibrous tissue within the breast. Fatty tissue tends to predominate.
