Anatomy of the breast Flashcards
anatomical location of breast tissue
anterior thoracic wall; overlaying pectoralis major
ribs 2-6 and costal catilage
extends form lateral margin of the sternum to mid-axillary
What does the deep surface of the breast lie on
deep fascia covering the muslces of the anterior and lateral aspect of the thorax
What does the mammary ducts converge to form?
15-20 lactiferous ducts
What two components does the connective tissue stroma have
Fibous anf fatty component
WHat does the fibrous stroma condense to form
suspensory ligaments
What are the two main functions of suspensory ligaments
Attach and secure the breast to the underlying fasia
seperate secretory lobules
What is the overall structure of the breast
Lobes made up of lobules consisting of clusters of alveoli containing lactocytes
What occurs during puberty in regards to breast development
Begins with evelation of the papilla, with a surge in oestrogen as well as growth hormone and IGF-1
Formation of the breast bud with elevation of the nipple as well as a small mound of breast tissue and enlargemnt of areola and nipple
Results in seconds mound on the breast which connects with the former
WHat occurs to breast during pregnancy
Increased oestrogen, progestrone and prolactin resulting in the breast increasing in water, electrolyte and adipose content
Increased vascular branching and dialated veins increas blood flow to breast
size and pigmentation of the nipples also increases
Sebaceous glands on the periphary of the areola enlarge and produce lubricant
Ductal, alveolar and myoepityhalial elements undergo marked hyperplasia
What happens to breast alveoli in response to progesterone during pregnancy
Breast alveoli bud from the ducts and expand outwards towards the chest wall
Breast alveoli are ballon-like structures lined with lactocytes, that surrounded by a net of contractile myoepithlial cells
What is lactation
procvess by which milk is synthesised and secreted from the mammary glands of the postpartum female breast
How does post-partum lactation take place
Sucking triggers sensory nerve impulses in the areola
This causes milk to be secreted from the lactocytes and fill the alveoli
Sucking also causes oxytocin release from the hypothalamus and neurohypophysis
oxytocin triggers myoepithelial cells to squeeze the produced milk into the ducts, into the sinuses and nipple pores
Why is no milk produced during pregnancy
Ostrogen, progesterone, and other placental hormones inhibit prolactin-mediated milk synthesis during pregnancy
Why are prolactin and oxytocin important in lactation
Prolactin causes establishment and maintenance of breast milk supply and oxytocin stimulates release of breast milk
What are the 3 main arterial supplies to breast
Lateral supply from axillary artery
Medial supply from the branches of internal thoracic artery
2-4th intercostal arteries via perforating branches
What are the two laterally supplying axillary arteries
Thoracoacromial a.
lateral thoracic a.
Innervation to breast
Anterior and lateral cutaneous branches of T2-T6 intercostal nerves
which intercostal nerve innervates the nipple
4th
What nerve is usually open to damage during lymph node dissection
The lateral cutaneous branch of T2 called intercostabrachial nerve
What is the lymphatic system
A system that produces , maintains and distributes lymphocytes that provide defence
Where are most lymphocytes stored
Lymphoid organs and tissues
spleen, thymus, tonsils, lymph nodes
What is lymph
Fluid that resembles plasma
What are lymphatic vessels
Begin in peripheral tissues and end at connections to veins
Tubes that assist the cardiovascular system
Remove tissue fluid from tissue spaces of the body and return to the blood
What are lymphatic tissues
Types of connective tissues containing lymphocytes
Essential for immunologic defence of the body
What are the lymphatic organs
Includes thymus and spleen
Production of lymphocytes for the immune response
Order of the lymphatic system
Lymphatic capillaries -> Lymphatic vessels -> Lymphatic trunks -> Lymphatic ducts -> Circulation
What are lymphatic capillaries
Branch through peripheral tissue
Present in almost every tissue and organ in the body
Originate in pockets
Large diameter and thin walls
Lymphatic trunk
Superficial and deep lymphatics converge to form Lymphatic trunks, which empty into large collecting vessels: thoracic duct and right lymphatic duct
Lymphatic ducts
Thoracic duct begins inferior to diaphragm
Base of thoracic duct is expanded, receiving lymph from abdomen, pelvis and lower limbs
Right lymphatic duct delivers lymph from right side of body, superior to diaphragm
What are lymph nodes
Kidney bean shaped
filter system to purify lymph
Serves as an early warning system for infection or abnormality
Minor injury may produce enlargement of nodes along a lymphatic vessel
What is chronic enlargement of lymph node called
Lymphadenopathy
What is the pattern of distribution of lymph nodes
Largest lymph node are located where peripheral lymphatics connect with the trunk, such as groin, axillae and base of neck
What does the lymphatic drainage of the breast tissue
Where does it originate
Axilla
Originates from breast lobules and flows into a sub areolar plexus
When does secondary breast cancer occur
When breast cancer cells spread from the first cancer in the breast through the lymphatic or blood system to other parts of the body
