Breast anatomy

polythelia

-accessory nipple -- milk line -- inferior -- females and males -#1 congenital anomaly

axillary lymph node categories

1) external mammary (pectoral): follows course of lateral thoracic vessels 2) scapular: follows course of subcapsular vessels 3) axillary: follows course of lateral axillar vessels -- 30-40 LN -- 75% lymph drainage -- #1 site for LN mets from breast cancer -- drains lateral half of breast and tail of spence 4) subclavicular: follows course of subclavian vessels 5) central: fatty tissue medial to axillary vessels 6) rotter's (interpectoral): between pectoral major and minor muscles

polymastia

-accessory breast tissue -- without nipple -- axilla -- men

skin layer

-0.5-2mm thick -epidermal cells -sebaceous glands and hair follicles -thicker in younger patients -nipple -- erectile tissue -- 15-20 small excretory ducts to drain milk -areola -- pigmented skin -- smooth muscle tissue -montgomery glands -- surface of areola -- secrete "protective" oily substance during lactation -morgagni tubercles -- bumps on areola -axillary tail of spence -- upper outer quadrant of axilla area -pectoralis muscle -- posterior to retromammary layer -- line chest wall from 2nd-6th rib from sternum to axilla -pectoralis minor posterior to pectoralis major -breast superior to 7th ribs -- inferior to 1st and 2nd rib -ribs posterior to pectoralis muscle

terminal ductolobular unit (TDLU)

-acini cells-- smallest functional unit -- less than 2mm -TDLU refers to 30-50 acinar cells grouped together in a lobule and their assiciated terminal duct -fibrocystic disease or adenosis have up to 5mm -# and size vary with age and hormone level -proliferation normally occurs during reproductive years and pregnancy/lactation -atrophy -- breastfeeding and postmenopausal -nearly all breast pathology originate in TDLU -most malignancies -- near junction of intralobar and extralobar -most are in anterior breast -- pathology arises in superficial half of mammary zone -- deep to superficial layer of the superficial fascia

nervous system

-anterior thoracic nerves -branch nerves from cervical plexus -circumflex nerve -long thoracic nerve -subcapular nerves -thoracic intercostal nerves -thoracodorsal nerve

vasculature

-arterial supply --lateral thoracic artery -- originates from axillary artery -- courses lateral and inferior along pectoralis major muscle -- supplies lateral breast tissue --internal thoracic artery (internal mammary artery) -- orginates at subclavian artery -- lateral to sternum -- supplies medial breast tissue -- used for coronary bypass surgery when other vessels unavailable (GSV, radial artery) -thoracoacromial artery --superior breast tissue -intercostal artery--inferior breast tissue -venous drainage --superficial venous system lies within subcutaneous fat tissue ---blood moves from superficial system to deep ---most distal veins line superficial fascia and drain blood centrally ---provides connection between breasts with potential mets --deep venous system consists of veins that follow arterial system ---primary route of venous drainage of breast ---includes internal mammary veins, lateral thoracic, axillary, subclavian, and intercostal veins ---drain into axillary vein, subclavian vein and SVC

premammary layer (subcutaneous fat)

-between skin and superficial layer of superficial fascia -fat related to age, obesity, and pregnancy -sebaceous cysts and lipomas occurs in this layer

mammary layer (grandular or parenchymal)

-between superficial and deep layers of superficial fascia -only layer that contains glandular tissue (functional tissue) -most pathology -epithelial -- functional tissue -- includes TDLU, lobules, lobes, lactiferous ducts -stromal -- structional tissue -- includes fat and connective tissue -each breast has 15-20 lobes of grandular tissue -lobes -- multiple lobules -- associated intralobular terminal duct -lobules -- grandular tissues -- contain functional epithelial cells (acini cells) that produce milk -intralobular terminal ducts from smaller lobules drain milk into ductal system once milk milk exits the lobules it enters the extralobular duct -extralobular terminal ducts converge into main interlobar duct -- drains all the milk from that cluster of lobules -- end at main duct -main ducts drain milk from each breast lobe (15-20 ducts) -- form pyramid shape -- focused to an apex at areola/nipple -widening of distal end of main ducts is referred to ampulla -- reservoir for milk prior leaving breast -interlobar or cooper ligament course between lobes from deep fascia of chest wall/axilla toward nipple to attach to anterior fascia of skin -interlobular ligament support breast parenchyma

Nipple inversion

-bilateral if congenital

lactiferous duct system

-double layer of epithelial cells -- reduce friction for easier milk flow -middle layer -- myoepethielial cells -- movement of milk -basement membrane forms outer layer -- in contact with intralobular stroma -nonlactating -- <2mm -- increase in size closer to nipple -lactating -- <8mm 1) intralobular terminal ducts -- carry milk from the acini 2) extralobular terminal ducts 3) interlobular terminal ducts -- travel between breast lobes to reach the main duct 4) main terminal duct -- end at lactiferous sinus or ampulla -- 2-3 mm 5) collection ducts or excretory ducts -- 15-20 openings that excrete milk from nipple 6) nipple

accessory node chains

-intramammary: lie within centimeter of posterior mammary artery -- extends from axilla to nipple -internal mammary: LN and vessels that follow internal mammary vessels -- drains medial breast -- mets drainage with medical cancer formation -intercostal/parasternal: adjacent to internal thoracic artery and vein -supraclavicular: adjacent to internal jugular vein and subclavian vein -- mets if level I,II, and II nodes are affected -- considered distant mets -- if involved -- prognosis poor

retromammary layer

-posterior to mammary layer -fat related to age, obesity, pregnancy -deep -breast motion over chest wall

axillary node classification

-surgical approach -location relative to pectoralis minor muscle -mets -axilla -- level 1 -- II -- III -sentinel node is usually level I -level I: lateral to pectoralis minor -- pectoral -- subcapular -- lateral -- paramammary nodes -level II: deep to pectoralis minor -- interpectoral and central nodes -level III: medial to pectoralis minor -- apical nodes

superficial fascia

-surrounds all mammary tissue -- separates breast into superficial and deep -superficial layer -- within premammary layer -deep layer -- posterior to mammary layer within retromammory space -irregularities of deep fascia posterior to a malignancy can indicate mets to chest wall

amazia

absence of functional breast tissue beneath a normal nipple/areola

Athelia

absence of nipple

milk line

axilla and inguinal region where breast tissue may form

amastia

failure of breast and nipple development