Superior Thoracic Aperture = Thoracic Inlet/Outlet

  • superior border T1, inner 1st ribs, jugular notch manubrium; slopes inferior from PàA
  • midline structures AàP:strap mm, SCM, thyroidea ima, inferior thyroid v, trachea, recurrent laryngeal n, oesophagus, ALL and prevertebral fascia
  • paired paramedian structures: innominate vv, lung apices, IMAs, vagus nn, phrenic nn, longus colli, symphathetic trunk and plexi
  • R lateral: brachiocephalic a (>R CCA and SCA), proximal R recurrent laryngeal n, R lymphatic duct
  • L lateral: L CCA, SCA, thoracic duct
  • suprapleural membrane (roof of thoracic cage; internal 1st rib > transverse process C7; above superior thoracic aperture)

Chest Wall


  • thoracic vertebrae
  • sternum (suprasternal/jugular notch, manubrium, angle [of Louis], body, xiphoid process)
  • stenebrae (portions of sternum; fuse upwards 15-25y; xiphoid fuses 40yo, manubrium fuses old age/never)
  • ribs (7 true, 3 false, 2 floating)
    • head with articular facets for vertebral body
    • neck (costotransverse lig > vertebrae above)
    • tubercle (costotransverse lig >own vertebrae) with articular facet for transverse process
    • posterior [and anterior] angles
    • subcostal groove
  • 1st rib has tubercle for scalenus anterior; groove for SCV ant)
  • 2nd rib has tubercle for 2nd head scalenus anterior on lateral border
  • costal cartilages (none in 1st rib, fused in ribs 8-10;slope up to sternum)
  • sternochondral joints
  • 1° oss of ribs at angle
  • 2° oss at head and tubercle (appear 15y, fuse 25y)

Rib Variants

  • cervical rib (1.4%, may > 1st rib; 50% bilateral
  • lumbar rib (costal element/transverse process fails to fuse with body))
  • pseudarthrosis of 1st rib (through midportion)
  • forked/bifid rib (duplication anterior portion)
  • rib fusion
  • bone bridging (focal joining by bone outgrowth)
  • rudimentary/hypoplastic rib (usually 1st rib)
  • supernumery or 11 pairs of ribs
  • costal cartilage calcification (males marginal bands, females central tongue

Sternal Variants

  • pectus excavatum (depression of lower end)
  • pectus carinatum (prominence of midportion)


  • dome right hemidiaphgram at 4th-7th anterior rib; 2cm higher than left (although left may higher if lots of gas in stomach/rectum)
  • moves 1cm with quiet respiration; 4cm deep; L>R
  • thickness 2-3mm with pleura and peritoneum; 5-8mm with pleura, and fundal wall stomach
  • dome 15mm higher than line between costophrenic and cardiophrenic angles


  • central tendon (>pericardium; right, middle and left leaflets)
  • muscular part (vertebral, costal and sternal portions)
  • costal part (>lower 6 ribs and cartilages)
  • sternal part (>xiphoid process)
  • lumbar/vertebral parts (lumbocostal arches-> crura-> vertebrae [R>L1-3, L>L1-2])


  • medial (psoas major, sympathetic trunk) and lateral (quadrates lumboraum, subcostal a&v&n) arcuate ligaments
  • caval hiatus (T8 in R crus; IVC [adventitial wall fused with central tendon], right phrenic n)
  • oesophageal hiatus (T10 in central tendon; oesophagus, vagus nn, oesophageal vessels)
  • aortic hiatus = retrocrural space (behind median arcuate ligament [<R and L crura] at T12; aorta, thoracic duct, azygos and hemiazygos vv)
  • superior epigastric vessels pass between sternal and costal origins
  • left phrenic n pierces central tendon
  • splanchnic nn piece each crus


  • inferior phrenic aa (<aorta) > abdominal surface
  • intercostal aa > costal margins
  • right and left phrenic nerves (<C3-C5 roots) > motor and central sensation of diaphragm
  • peripheral sensation > intercostal nn


  • partial/incomplete muscularisation = partial eventration (5%, usually ant-med-R with elevation of portion of hemidiaphragm)
  • accessory hemidiaphragm = partial reduplication of the diaphragm (>pericardium, anterior diaphragm, posterior chest wall; trapping some/all of lower lobe; R≫L)
  • congenital diaphragmatic hernia (0.02%, Bochdalek [posterolateral], Morgagni [anteromedial parasternal], septum transversum or hiatal)


  • pectoralis major (sternum and clavicle> humerus)
  • pectoralis minor (ribs> humerus)
  • serratus anterior (ribs> scapula)
  • teres major (scapula> humerus)
  • subscapularis (scapula> humerus)
  • rhomboid major and minor (vertebrae> scapula)
  • erector spinae
  • trapezius (occipital &vertebrae> spine scapula)
  • external, internal and innermost intercostals muscles
  • subcostal muscles (post; span several ribs)
  • transverse thoracis (ant; sternum > sup-lat > internal ribs)
  • levator costarum (under erector spinae; transverse process > posterior rib below)
  • serratus posterior superior (upper spinous processes> ribs)
  • serratus posterior inferior (lower spinous processes> ribs)

Intercostal Arteries

  • neurovascular bundle (betw internal and innermost mm)
  • subcostal groove
  • anterior intercostal arteries (paired); upper 6 <IMA, lower 3 < musculophrenic a
  • posterior intercostal arteries (single) upper 2 < supreme intercostal a (<costocervical trunk), lower 9 < aorta
  • spinal branches (of posterior intercostal aa)
  • internal thoracic/mammory artery (IMA) > musculophrenic artery + superior epigastric artery

Intercostal Veins

  • anterior intercostal veins (paired) > musculophrenic and internal thoracic vv
  • internal thoracic/mammary veins > brachiocephalic vv (<ant intercostal, pericardiophrenic and mammary vv)
  • posterior intercostal vein (11 single) > brachiocephalic v and azygos system
    • 1st > supreme intercostal vv > brachiocephalic
    • 2nd-3rd/4th > superior intercostal vv > azygos v (R) and L brachiocephalic v (L)
    • 4th/5th-11th R > azygos v
    • 4th/5th-8th L > accessory hemiazygos v
    • 9th-11th L > hemiazygos v

Azygos System of Veins

  • azygos vein (L2 from ascending lumbar + subcostal vv; may comm with IVC) and arch @ T4 (over hilum R lung > posterior SVC just above pericardium behind 3rd costal cartilage)
    • A = R crus diaphragm
    • P = vertebrae, R posterior intercostal aa
    • L = aorta, thoracic duct, trachea, oesophagus
    • R = R lung
    • <accessory and hemiazygos vv, posterior intercostal, oesophageal, pericardial, mediastinal and R bronchial vv (near termination)
  • hemiazygos vein (L ascending lumbar + subcostal vv ; may comm with L renal v >azygos @ T8 [behind aorta]; < L lower 3-4 intercostal, mediastinal and oesophageal vv)
  • accessory hemiazygos vein (> azygos @ T7 and/or left superior intercostal vein [> left brachiocephalic]; < 4th-8th L posterior intercostal, L bronchial vv)
  • common trunk for hemiazygos and acc. hemiazoygos veins (V)
  • SVC obstruction causes downhill varices through oesophageal plexus to left gastric > portal v


  • vagus nn (CNX, motor and sensory fibres) > carotid sheath > posterior pulmonary plexus (behind bronchi); A = IJV, brachiocephalic v, main bronchi)
    • recurrent laryngeal nn ( R around SCV, L around ao.arch)
    • anterior and posterior oesophageal plexuses > oesophageal hiatus > anterior and posterior vagal trunks
  • phrenic n (C3-5 > motor of diaphragm; A = SCV; P = SCA, SVC [R], ao.arch [L], L superior intercostal v [L], hila)
  • ventral rami > intercostal nerves (11) >muscular branches, lateral cutaneous n (ant and posterior branches), anterior cutaneous n
    • subcostal nerve (12th intercostal n)
  • dorsal rami > muscular (spinal mm), medial and lateral cutaneous branches

Sympathetic Chain

  • sympathetic trunk and ganglia (paraspinal gutters > medial arcuate lig > lumbar sympathetic trunk)
  • cervicothoracic (stellate) ganglion (1st thoracic and lower cervical ganglia)
  • thoracic aortic plexus (<upper 5 ganglia and greater splanchnic nerve)
  • pulmonary plexus (<2nd-5th/6th ganglia)
  • cardiac plexus (<2nd-5th ganglia)
  • greater splanchnic nn (5th -9th/10th ganglia; medial to chain)
  • lesser splanchnic nn (<9th-10th/11th ganglia, lateral to greater)
  • lowest/least splanchnic nn (lat to lesser)

Lungs and Airways

  • lung and visceral pleural margins – 3cm above medial 1/3 clavicle, 6th rib in mid-clavicular line, 8th rib in mid-axillary line, 10th rib paravertebrally
  • costal, mediastinal, apical and diaphragmantic surfaces

Trachea and Bronchi

  • trachea (15 x 2cm cricoid cartilage [C6] > carina [sternal angle T4-T6])
    • 15-20 tracheal rings bridged posterior by trachealis m
    • upper trachea <inferior thyroid a&v
    • lower trachea < bronchial a&v
    • cervical part (A = isthmus thyroid, inferior thyroid v, strap mm; P = oesophagus, recurrent laryngeal nn; lateral = thyroid lobes, CCA)
    • thoracic part (A = brachiocephalic and left CCA, left brachiocephalic v; P = oesophagus, left recurrent laryngeal n; L = ao.arch, L CCA, L SCA; R = R vagus n, azygos v arch, pleura)
    • indentation from aortic arch
  • carina (@rest sternal angle at T5, inspiration T4, expiration T6; carinal angle 65° [25°R, 40°L], larger in children and recumbency)
  • bronchi (w cartilage)
    • right main bronchus (A = SVC, R PA; P = azygos v; S = azygos arch)
    • intermediate bronchus = bronchus intermedius (R > mid and inferior lobe bronchi)
    • left main bronchus = hyparterial bronchus (A = pulmonary trunk; P = oesophagus, descending aorta; S = ao.arch, L PA
    • lobar bronchi
    • segmental bronchi (6-20 divisions)
  • bronchioles (no cartilage)
    • terminal bronchiole
  • bronchial arteries (<aorta) and veins(>azygos and hemiazygos vv)


  • tracheal/eparterial bronchus (>RUL [esp apical segment] or LUL)
  • accessory cardiac bronchus (bronchus intermedius or right main bronchus > medial > blind end or acc lobe)
  • paracardiac bronchus (5%, <med lower lobe)
  • tracheoesophageal fistula
  • situs inversus

Bronchopulmonary Segments

  • right superior lobe
    • apical (S1), posterior (S2) and anterior (S3) segments
  • right middle lobe
    • lateral (S4) and medial (S5) segments
    • right inferior lobe
    • superior/apical (S6), medial basal (S7), anterior basal (S8), lateral basal (S9) and posterior basal (S10) segments
  • left upperlobe
    • superior division = culmen > apicoposterior (S1+2), anterior (S3) segments
    • lingular division > superior (S4) and inferior (S5) segments
  • left inferior lobe
    • superior/apical (S6), anteromedial basal (S7+8), lateral basal (S9) and posterior basal (S10) segments
  • pores of Kohn (openings in alveolar walls connecting lumens)
  • canals of Lambert (betw terminal bronchioles and adj alveoli)


  • diaphragmatic = diaphragm (basal segments)
  • costal = ribs, intercostal muscles (all except medial basal)
  • apical = suprapleural membrane (R S1, L S1+2)
  • mediastinal = brachiocephalic vv (R S1, LS1+2), trachea (R S1, L S1+2), oesophagus (R S2, L S1+2), SVC (R S3), RA (R S5,7), LV (L S4,5), descending aorta (L S10)


  • separate apicosuperior or anteromedial basal segments
  • trifurcation or quadrification of segmental bronchi

(Secondary Pulmonary) Lobules = 20-30mm

  • lobule = terminal bronchiole, acinus
  • acinus (8-20mm, up to 10 in each lobule)
  • respiratory bronchioles (3-8 divisions; mm, elastin)
  • alveolar ducts
  • alveoli sacs and alveoli
  • interlobar septa (contain veins and lymphatics)
  • central bronchovascular bundle (b+a+l)
  • artery-bronchus ratio (erect upper=0.85, lower = 1.34)
  • subpleural lymphatics (pleura and interlobar septa)
  • interlobar veins
  • type 1 pneumocytes less in number but is most of surface area, for gas exchange. unable to replicate
  • type 2 pneumocytes much more numerous, found at alveolar-septal junction. start to develop at 24/40. produce and secrete surfactant, can replicate and differentiate to replace type 1 pneumocytes.


  • visceral and parietal pleura
  • costophrenic and cardiophrenic sulci
  • costomediastinal recesses
  • intercostal stripe (costoparietal pleura, extrapleural fat, endothoracic fascia, innermost intercostal muscle)
  • oblique/major/greater fissure (~5th rib; T4/T5 >ant-inf diaphragm)
  • transverse/minor/lesser fissure (~midaxillary 6th rib, 4th costal cartilage)
  • reflection around lung root
  • pulmonary ligament (reflection of pleura hanging down from hila; may extend to diaphragm or have free edge)
  • parietal pleural margins – 3cm above medial 1/3 clavicle, 2 ribs below lung margins (8th, 10th, 12th ribs)
  • parietal pleura < systemic vessels
  • visceral pleura < bronchial and pulmonary vessels

Variants/accessory fissures

  • incomplete (50%) or absent (10%) transverse fissure
  • azygos fissure and ‘lobe’ (also contain parietal pleura)
  • left ‘azygos’ fissure (1%, involving hemiazygos and L superior intercostal vv)
  • inferior accessory fissure = Twining’s line (20%, separating medial basal segment, sup-med from medial diaphragm)
  • superior accessory fissure (5%, separating superior seg of lower lobe; horizontal below minor fissure)
  • left minor fissure (10%, separating lingular)

Bronchial Vessels

  • supply bronchi, visceral pleura, connective lung tissue
  • right bronchial artery (< 3rd-4th posterior intercostal or L bronchial at ~T5/T6)
  • left bronchial arteries (2; <thoracic aorta @T5)
  • deep bronchial veins (> main pulmonary vein/LA)
  • superficial bronchial veins (>azygos and L superior intercostal/accessory hemiazygos vv)
  • 2nd right bronchial artery (V<3rd intercostal a)
  • bronchial arteries < SCA/IMA (V)

Pulmonary Arteries

  • pulmonary trunk (5cm, entirely covered by pericardium)
    • A = R&L atrial appendages; P àA/S/P= aorta; A/L = left lung
  • right main pulmonary a (A = ascending aorta, SVC, R superior pulmonary v; P = right main bronchus; S = carina)
    • interlobar artery (lat to bronchus intermedius; <16mm)
  • left main pulmonary a (A = L superior pulmonary v; P àI = left main bronchus; S = ligamentum arteriosum)
  • left 1cm superior to right hilar point (where superior pulmonary v crosses anterior to main pulmonary a)
  • segmental arteries post-lat to bronchi (>alveoli)

Pulmonary Veins

  • pulmonary veins > intersegmental septa > superior and inferior veins (above/below oblique fissure; ant-inf to PAs) > LA
  • 3 right pulmonary (V)
  • confluent R or L pulmonary vein (V)
  • anomalous pulmonary venous drainage (V, partial or complete, pulmonary v > IVC/SVC or R side of heart)


  • superficial plexus (<surface of lungs and fissures) > bronchopulmonary nodes > tracheobronchial and paratracheal nodes
  • deep channels follow pulmonary vesels > hila


  • superior compartment/division (sup to sternal angle, lower T4 body; aortic arch and vessels, brachiocephalic vv, SVC, trachea, oesophagus, thoracic duct, lymph nodes, nerves)
  • inferior compartment
  • anterior compartment (ant. to pericardium and aortic root; thymus, mammary vessels, lymph nodes)
  • middle compartment (heart, pericardium, nerves, lymph nodes, great vessels)
  • posterior compartment (post. to trachea, pulm vessles, pericardium; descending aorta, oesophagus, azygos v system, thoracic duct, para-aortic, para oesophageal and paraspinal nodes)

paravertebral compartment (from vertebral column)

Mediastinal Lymphatics

Thoracic duct (2-8mm)

  • < lymph from below diaphragm, posterior right chest wall, left body above diaphragm, L subclavian trunk (<L arm)
  • cysterna chyli > aortic hiatus in diaphragm > T5>left >C7 > over L SCA and L lung 3-4cm above clavicle > jugulosubclavian junction >L SCV
  • many valves in last 5cm
  • A = oesophagus
  • P = vertebra, R posterior intercostal aa, terminal hemiazygos and accessory azygos vv
  • R = azygos vein
  • L = aorta

Right lymphatic duct (1cm)

  • < right jugular trunk (<R head)
  • < R subclavian trunk (<R arm, R thoracoabdominal wall to umbilicus and iliac crest, R breast)
  • < R bronchomediastinal trunk (<hemithorax, R heart, R lung, part of liver)
  • R jugulosubclavian junction (2 semilunar valves)
  • absent right lymphatic duct (V, tribituraries enter separately)

Mediastinal Lymph Nodes

  • American Thoracic Society regional nodal stations:
  • X = supraclavicular nodes

Superior mediastinal nodes:

  • 1 = highest mediastinal
  • 2 = upper paratracheal nodes (aorta>apex lung)
  • 3 = prevascular and retrotracheal
  • 4 = lower paratracheal nodes (aorta>carina), including azygos nodes (R tracheobronchial angle)
  • pretracheal nodes (ant to trachea)

Aortic nodes:

  • 5 = subaortic/aortopulmonary nodes
  • 6 = para-aortic (aascending aorta or phrenic)

Inferior mediastinal nodes:

  • 7 = subcarinal nodes
  • 8 = paraoesophageal nodes (below carina)
  • 9 = pulmonary ligament nodes

N1 nodes:

  • 10 = hilar/tracheobronchial nodes (carina to bronchi; incl bronchopulmonary nodes in hilum)
  • 11 = interlobar
  • 12 = lobar
  • 13 = segmental
  • 14 = subsegmental
  • intrapulmonary nodes (distal to main bronchi)

LN < 10-15mm, brachiocephalic veins <5mm, paracardiac rarely seen, retrocural <6mm

Mediastinal Spaces

  • pretracheal space (betw trachea, SVC/R brachicephalic v, aorta)
  • aortopulmonary window (betw aortic arch, pulmonary artery, trachea/oesophagus, lung; ligamentum arteriosum, L recurrent laryngeal nerve)
  • subcarinal space (betw main bronchi, oesophagus)
  • right paratracheal space/stripe
  • posterior tracheal space/stripe
  • tracheobronchial angle (containing azygos vein)
  • anterior junction = prevascular space (ant. to aorta and pulmonary a; contain L brachiocephalic v, fat, LNs, thymus, phrenic nerve)
  • posterior junction (post to trachea, heart, oesophagus)
  • azygo-oesophageal recess
  • supraazygos recess
  • paravertebral/paraspinal space (R>L, LNs, fat, intercostal v, pleura; <10mm)
  • retrocrural space (betw mediastinum and retroperitoneum, contain aorta, azygos, hemiazygos, thoracic duct/cisterna chyli)
  • diaphragmatic crura (ligs blend with anterior longitudinal lig)

Normal Mediastinal Contours on X-Rays

  • left mediastinal contour (carotid a, subclavian a, posterior aortic arch/knuckle/knob, aortic-pulmonary window, main pulmonary a, LV)
  • right mediastinum contour (brachiocephalic v, SVC, RA)
  • lat aortic arch ‘nipple’ from L superior intercostal vein
  • anterior junction line (below clavicles running inferior to L due to diff anterior extent of lungs > RVOT; anterior to major aa)
  • posterior junction line = oesophageal ‘mesentery’ (4 layers of pleura; apices/T1>ao.arch, may reform inferiorly; posterior to trachea, heart, oesophagus)
  • right paratracheal stripe (≤ 3mm of R tracheal wall; clavicles to azygos v)
  • left paratracheal stripe (sup to ao.arch, may be obscured by L SCA or L CCA)
  • azygooesophageal line (below azygos arch; azygos v closely related to R P/lat oesophagus with R lung tucking behind [=azygooesophageal recess])
  • paravertebral/paraspinal line (R sharper than L due to aorta stripping off pleura; <10mm)
  • aortopulmonary mediastinal stripe (reflected pleura from ao.arch to L PA, lateral border of AP window)
  • posterior tracheal stripe/band = tracheoesophageal stripe (lat XR, posterior trachea and anterior oesophagus walls <2-3mm if air in oesophagus; <1cm if oesophagus collapsed)
  • retrosternal line (diff anterior extent of L and R lungs)
  • hilar point (where upper lobe v crosses descending pulmonary artery; R @6th posterior interspace, 1cm lower than L)
  • hilar angle (betw vessels at hilar point, 120°)


  • betw left brachiocephalic v and right pulmonary a, anterior to trachea in ant/sup mediastinum
  • left (higher and larger) and right lobes
  • may extend to posterior mediastinum or be entirely below ao.arch
  • 8/9mm-5/6mm (thick) x 50-70mm (long)
  • lobules with medulla and cortex separated by vascular septa
  • not seen on CXR >5yo
  • A = ribs
  • P = pericardium, great vessels, trachea


  • 2nd-6th anterior ribs, invested by split fascia of the chest wall (ant/superficial and post/deep layers)
  • parenchyma (glandular tissue) and stroma (fibrofatty)
  • lobes (15-20, < single lactiferous lobar duct)
  • terminal duct lobular unit (TDLU) = ductules/acini + intralobular and extralobular terminal ducts
  • segmental ducts > lactiferous ducts > lactiferous sinuses
  • interlobular stroma (fibrofatty tissue) contains elastic fibres supporting large ducts
  • intralobular stroma encloses lobules with hormonally responsive loose tissue with scattered lymphocytes
  • retromammary space (2nd to 6th/7th costal cartilage, sternal edge, mid-axillary line; retroglandular fat)
  • upper outer quadrant (most fibroglandular tissue) > axillary tail of Spence
  • suspensory ligaments of Cooper (skin/nipple > fascia of pectoralis
  • nipple (longitudinal and circular smooth m; 4th intercostal space)
  • areola
  • Montgomery’s tubercles (sebaceous glands on areola)


  • A = skin, subcutaneous fat
  • P = pectoralis major, serratus anterior, rectus abdominus
  • med = sternum
  • lat = axilla

Vascular Supply

  • medial mammary branches of the IMA > piece intercostal space and pectoralis > 60% of breast, medial and central
  • lateral mammary/thoracic artery < axillary artery > 30% of breast, upper outer quadrant
  • lateral mammary branches of lateral cutaneous branches of posterior intercostal arteries
  • veins > internal thoracic, axillary, subclavian and azygos vv


  • superficial > deep (perilobular and deep subcutaneous plexus) > centrifugally > axillary and internal mammary (<5%) chains
  • axillary nodes (level 1 [inferolateral], level 2 [post] and level 3 [superomedial] relative to pectoralis minor)
    • apical/subclavian nodes
    • central nodes
    • lateral/brachial nodes
    • posterior/subscapular nodes
    • anterior/pectoral nodes\
    • interpectoral/Rotter’s nodes
  • parasternal nodes
  • pathways to anterior mediastinal, inferior phrenic/subdiaphragmatic nodes, opposite breast and liver

Pathophysiological Changes

  • prepubertal – blind-ending ducts
  • menarchy – development of ductules/acini
  • increase in oestrogen/progesterone > epithelial proliferation, increased number of acini per lobule, stromal oedema
  • fall in oestrogen/progesterone > epithelial apoptosis
  • pregnancy> marked epithelial proliferation and acini
  • prolactin, insulin, growth hormone > secretory acini with intracellularvacuoles
  • reduced hormones/menopause> fibroglandular regression

Mammographic Anatomy

  • pectoralis major (posterior> nipple level)
  • inframammary fold
  • retroareolar ducts
  • vascular bundles (a<v)
  • suspensory ligament of Cooper (shallow curvilinear)
  • fibrous septa
  • intramammary lymph nodes with fatty hilum
  • age increases subcutaneous fat layer, fatty interlobular deposits
  • Wolfe classification of distribution of fibroglandular tissue: N1 (normal, most adipose), P1 (<1/4 of breast), P2 (>1/4 of breast), DY (no ductal or nodular appearance)
  • calcification of sebaceous glands (fine, dense, punctuate, tiny central lucency)
  • skin lesions with air halo
  • arterial calcification

Ultrasound Anatomy

  • structural adipose tissue hypoechoic cf echogenic organic fat
  • acoustic shadowing with malignancy, fibroglandular tissue and Cooper’s ligaments


  • incomplete regression of the milk line (2-6%)
  • polythelia = accessory nipple (along milk line, usually just inferior to breast)
  • double areolar nipple
  • polymastia = accessory breasts
  • accessory glandular tissue (along milk line axilla to groin)
  • amastia = absence of nipple and breast tissue
  • amazia = absence of breast tissue
  • asymmetry of breast tissue (3%)
  • nipple inversion