Anatomy Flashcards
The breasts initially develop from the?
ectoderm. As paired mammary ridges (or milk lines)
What week of gestation does the breasts develop?
4th
How many lobes of glandular tissue develop?
15-20
Cooper’s ligaments and fat develop from the?
mesoderm
Are the rudimentary mammary glands the same at birth in both males and females?
Yes
What makes the areolae thick?
Glands of Montgomery
Witch’s Milk:
Enlargement of newborns ductal system, which causes secretions similar to colostrum. This happens due to a decrease in maternal estrogen in the newborn’s bloodstream which stimulates the pituitary gland.
Corpus luteum secretes what after ovulation?
Progesterone
What causes breast fullness and tenderness after ovulation?
Proliferation of the epithelial cells within TDLU and subsequent enlargement of the lobules and terminal ductules.
If pregnancy occurs, the breasts reach functional maturity influenced by what hormones?
estrogen, progesterone, prolactin and placental lactogen
Acini become fully formed and functional once puberty is completed.
False – when pregnancy and lactation have occurred
What hormones causes lactation to begin?
drop in progesterone, alveolar epithelium begins to secrete milk. Then, in response to sucking or crying, oxytocin causes contractions to the epithelial cells which forces the alveoli to secrete milk
What part of the breast secretes milk?
Alveoli
When do the mammary glands begin to atrophy?
40yrs — after menopause the glands further involute and are replaced by fat and CT
What’s responsible for duct development and division and the deposition of fatty tissue?
Estrogen
What’s responsible for alveolar (acini) and lobular development?
Progesterone
List some changes that occur during pregnancy:
areola darkens and increases in size (color lightens after lactation is done, but never is the pre pregnancy state)
Colostrum
Little water or fat, but high in antibodies
What hormones have to be right in order for the alveoli to produce milk?
Prolactin (ant pituitary gland)- high
Estrogen/progesterone- low
What hormone inhibits milk production during pregnancy?
estrogen and progesterone from the placenta
Milk is produced how many days post partum?
1-3days
What continues the alveoli in producing milk?
Sucking motion stimulates the anterior pituitary gland to release prolactin
How does milk travel from the breast tissue through the nipple?
Collects in the alveolar cells in the clustered alveoli, then into the secondary tubules. These converge to form a lactiferous duct. Near the nipple, the ducts expand to form an ampulla (lactiferous sinus), where milk is stored
Oxytocin stimulates the milk ejection reflex, and also ?
the contraction of myoepithelial cells
As a woman ages, the breast tissue changes from glandular to fatty. What delays this?
HRT
The breast is classified as a modified and highly specialized type of what gland?
Apocrine
What’s the function of the apocrine gland?
To secrete milk during lactation.
What’s the purpose of the areola?
To lubricate the nipple during lactation through the action of sebaceous areolar glands or glands of Montgomery.
How many lactiferous duct openings are there?
20
The entire breast is enveloped in ?
Superficial pectoral fascia – or connective tissue
What supports the breast?
Cooper’s ligaments
What are the 3 layers of the breast?
Subcutaneous, mammary, retromammary
Describe the subcutaneous layer of the breast:
bounded by skin anterior and fascial plane posteriorly. Skin thickness <2mm. Mostly composed of fat lobules separated by Cooper’s ligaments
Describe the retromammary layer of the breast:
Primarily composed of fat. Bounded anteriorly by the mammary layer and posteriorly by the deep fascia covering the pec muscle
Are fat lobules smaller in the subcutaneous or retromammary layer?
Retromammary
The mammary layer is contained within?
the superficial and deep layers of the superficial pectoral fascia
What layer of the breast are we most concerned for disease and changes w advancing age and pregnancy?
Mammary layer
There is no what immediately beneath the nipple and central areola?
fat
Tail of Spence aka?
Axillary tail – extends from the UOQ to axilla
The breast receives its arterial blood supply from which arteries?
Thoracic branch of the axillary and lateral thoracic arteries including: internal mammary, lateral thoracic, intercostal artery and perforating arteries (least important)
What is the principle source of arterial blood supply to the breast?
Internal mammary artery (arising from the prox SCA)
What are the landmarks for locating the internal mammary (parasternal) chain of LN’s?
IMA and IMV
What supplies blood to the medial aspect of the breast?
Perforating branches of the IMA
What supplies blood to the lateral aspect as well as the deep portions of the breast?
Branches of the lateral thoracic and intercostal arteries
What is the circulus venosus?
Venous anastomotic circle around the base of the nipple
What provides the majority of the sensory innervation to the breast?
Lateral and anterior cutaneous branches of the intercostal nerves. Also the supraclavicular nerve
Lymphatic drainage begins within the lobules and drains?
intramammary LN’s
Plexus of Sappey
when lactiferous ducts converge at the nipple at the subareolar plexus. Play an important role in LN mapping as all lymphatics of the breast communicate through this plexus
What’s the primary route of lymphatic drainage?
Posterior intercostal nodes to the axillary lymph nodes (75%)
What’s the secondary route of lymphatic drainage?
internal mammary chain (20-25%)
What’s the least important role in lymphatic drainage?
Subcutaneous LN’s (5%)
There are 8 LN groups, list them
external mammary, scapular, axillary, central, subclavicular, interpectoral, internal mammary, supraclavicular
How are axillary LN’s subdivided ?
By their relationship to the pectoralis minor muscle
Level 1 (low) nodes are located:
lateral to pec minor
Level 2 (middle) nodes are located:
posterior to pec minor
Level 3 (upper) nodes are located:
medial to pec minor (subcl, infracl, and apical nodes)
What are Rotter’s nodes:
1-2 LN’s that are located between the pec minor and major muscles. Along the pectoral branch of the thoracoacromial artery
Approximately 75% of the lymphatic vessels drain to the 30 or so regional LN’s through the nodes at
L1
The lumen of each duct is lined with:
epithelial cells
What lines the outside of a duct?
myoepithelial cells
Epithelial and myoepithelial cells are composed of what? What does this aid in?
Contractile fibers – transport of milk
What’s the functional unit of the breast?
Terminal duct lobular unit (TDLU)
Intralobular terminal duct (ITD) drains the
multiple, small, blind ended ductules (acini)
Extralobular terminal duct (ETD) drains the
lobule
What is the target zone for a lobule:
Junction of the intra and extralobular terminal ducts, as it is the side of 50% of precancerous epithelial proliferations
Each TDLU consists of ? Each lobule consists of?
lobule and extralobular terminal duct. Intralobular terminal duct and ductules
Tissue types in the breast can be described as hyper or hypoechoic, when comparing it to the:
subcutaneous fat
How does the skin layer appear on US
two, parallel, echogenic bands on either side of a hypoechoic central layer
Skin layer thickness
<2mm
Pectoralis minor lies how to the major?
Posterior, superior and lateral
What muscle is located deep to the lateral third of the breast and forms the medial wall of the axilla?
Anterior serratus
Normal ducts should not exceed
2mm (non lactating)
Ductal ectasia often occurs in the presence of
fibrocystic disease and mastitis
Ductal ectasia symptoms:
milky discharge, sometimes w pain in subareolar region
What percentage of palpable breast cancers have LN involvement?
40-50%
Cortical thickness of a LN cannot measure more than
4mm
What’s the most significant difference between a normal and abnormal node?
Fatty hilum
LN’s in the OUQ should measure less than
1.5-2cm
Patients with ____________________ have a higher risk of cancer reccurence.
Extra-nodal extensions (ENE)
What are signs of extra-nodal extensions (ENE)?
Perinodal edema and matted LN’s (2-3 nodes appear fixed in place during real time scanning)
What is interval breast cancer?
Cancers that are present, but not caught on a woman’s last screening mammography exam. As well as those that developed after the exam
What does the male breast lack?
Cooper’s ligaments and acini
What’s the most common reason for a male breast US?
Gynecomastia or asymmetry
What’s the most common benign male breast mass? Second most common?
Gynecomastia, lipoma
What is thought to be the primary cause of gynecomastia? Secondary?
Primary - estrogen concentration
Secondary - proliferation of ductal and stromal elements
Dendritic gynecomastia
presents in gynecomastia patients who have been symptomatic for over a year. Small, hypoechoic tissue extending into the subareolar tissue and sometimes UOQ
Diffuse gynecomastia
appears similar to dense female breast tissue, hyperechoic
What is pseduogynecomastia:
accumulation of pectoral fat stored behind and around the nipple area
What’s the risk of breast cancer in males?
1%
What are the symptoms of breast cancer in males?
Unilateral, painless, palpable mass (80-90%). People can also present w nipple discharge (10-15%)
What’s the most common type of breast cancer in males?
Invasive or infiltrating ductal carcinoma, and then DCIS.
Do transgender women have similar breast tissue to normal women?
Yes. They develop ducts, lobules and acini.
Internal mammary artery is now known as:
internal thoracic artery
Lactiferous duct system of the breast is best evaluated how?
radial and anti radial scan plans
Risk factors of male breast cancer:
advanced age
radiation exposure to chest at a young age
occupational heat exposure
treatment of prostate cancer w estrogen based hormones leading to hyperestrogenism
family hx of a first degree male or female relative
BRCA1 or BRCA2 gene
