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THORAX
Cavity divided into:
R+L pulmonary cavities: contain lungs and pleura
Central mediastinum
Superior thoracic aperture: 5x10cm
Posterior: T1
Lateral: 1st ribs and costal cartilages
Anterior: sup border of Manubrium
Inferior thoracic aperture: Posterior: T12
Postlat: 11th and 12 ribs
Ant lat: costal cartilages 7-10 (form subcostal angle)
Anterior: xiphisternal joint
Bony Characteristics
True (vertebrocostal, 1-7)
False (vertebrochondral, 8-10)
Floating (vertebral, 11-12): do not articulate with transverse ligaments
Head: 2 facets articulate with it’s vertebra and 1 above (except 1, 10, 11 which have only 1
facet);
Costovertebral joints: synovial plane jt; demifacets separated by crest which attaches to IV
disc by intra-articular ligament which separates into 2 synovial cavities; each joint surrounded
by a capsule and anteriorly has radiate sternocostal ligament
Tubercle: at junction of neck and body, have articular part which articulates with transverse
costal facet of transverse process of vertebra at costotransverse joint (synovial plane jt,
costotransverse, lat and sup CT ligs support); and nonarticular part for costotransverse
ligament. Aperture of sup CT lig allows passage of spinal nerve and post branch of IC artery
Body: internal surface has inf costal groove for intercostal nerves and vessels
Costochondral joints: hyaline cartilaginous; no movement occurs at this joint
Interchondral joints: plane synovial, strengthened by interchondral ligs; articulation between
9-10th ribs are fibrous
1st rib: only 1 facet, 2 grooves on sup surface – ant for subclavian vein, post
for subclavian artery and brachial plexus - separated by scalene tubercle
(attachment of scalenus ant muscle), behind post groove is attachment for
scalenus medius; serratus ant attaches to lat aspect; no angle; has 1Y
cartilaginous sternocostal joint
2nd rib: has tuberosity for serratus anterior, scalenus post also attached; has
atypical synovial double cavity sternocostal joint
3-7 sternocostal joints are atypical synovial single cavity
Costal cartilages 7-10 form costal margin
Intercostal spaces named according to RIB ABOVE
Space below 12th rib is subcostal space – subcostal nerve = ant rami T12
spinal nerve
Vertebrae: sup and inf costal demifacets (except T1, 10-12); costal facets on
transverse processes for articulation with tubercles of ribs
Manubrium: has clavicular notches, below which is the syndochondrosis of
1st rib; jugular notch lies at inf border of T2, Manubrium at T3-4 – post is
arch of aorta and merging of brachiocephalic veins to SVC (enters heart
behind R 3rd costal cartilage; ½ facet for 2nd rib; manubriosternal junction is
2Y cartilaginous joint
Sternum: 17cm; T5-9; costal notches up for 2-7th ribs; 3 transverse ridges mark fusion of sternal
synchondroses at 3rd 4th and 5th articular depressions; sternal angle at T4-5 IV disc; ant to R heart; pec
major and SCM attach to ant, sternohyoid and sternothyroid attach to posterior
Xiphoid process: at T10; midline marker of sup aspect of liver; ½ facet for 7th rib; xiphisternal joint is 2Y
cartilaginous, fuses by 40yrs
Sternocostal joints: 1st is primary cartilaginous (syndochondrosis of 1 st rib), 2-7th is synovial plane
(reinforced by radiate sternocostal ligs)
Sternoclavicular: saddle type synovial; ant and post sternoclavicular and costoclavicular ligs; supplied by
cervical plexus
Manubriosternal: secondary cartilaginous
Xiphisternal: primary cartilaginous; at T9; ossifies with age; costoxiphoid ligaments, diaphragm,
transversis thoracis, linea alba and RA attach
Note: domes of diaphragm rise to level of 4th ribs
Females: smaller, sternum shorter, upper margin of sternum level with lower body T3 (males T2), upper
ribs moveable
Muscles of Chest Wall
Serratus posterior sup: from nuchal lig, spinous processes C7-T3
 sup borders 2nd-4th ribs; nerve = 2nd-5th IC nerves; action =
elevate ribs
Serratus posterior inf: from spinous processes T11-L2  inf
borders 8th-12th ribs near angles; nerve = ant rami T9-12 thoracic
spinal nerves; action = depress ribs
Levator costarum: transverse processes T7-11  subjacent ribs
between tubercle and angle; nerve = post rami C8-T11; action =
elevate ribs
Ex intercostal: inf border ribs  sup border ribs; from tubercles
of ribs to Costochondral junction where replaced by membrane;
nerve = IC; action = elevate ribs in forced inspiration
In intercostal: inf border ribs  sup border ribs; from sternum to
angle of rib then replaced by membrane; nerve = IC; action =
depress/elevate ribs in forced expiration. Note innermost IC
separated from in IC by IC nerves and vessels (pass 2 IC spaces)
Subcostal: internal lower ribs near angles  sup border ribs (2-3
below), running in same direction as in IC; nerve = IC; action =
like in IC (pass 2 IC spaces)
Transverse thoracic: post lower sternum  internal costal
cartilage; nerve = IC; action: weakly depress ribs
Intercostal space: contains VAN from sup to inf
Pectoral fascia: immediately post to breast
Clavipectoral fascia: deep to above, suspended from clavicle
Endothoracic fascia: deep to above, lines thoracic cage; becomes suprapleural membrane over apices
Factoid: accessory muscles of inspiration: scalene, SCM, quadratus lumborum, erector spinae, pec major
Accessory muscles of expiration: in TC, RA, ex oblique, in oblique, TA
Upper ribs have pump-handle movement
Nerves of Thoracic Wall
Supplied by 12 thoracic nerves
Ant rami: run in IC space; 12th forms subcostal nerve; run in endothoracic fascia between parietal
pleura and in IC membrane in middle of IC space  pass between innermost in IC and in IC, in
costal groove; give rise to lat cutaneous branches (ant and post branches) at MAL, become ant
cut branch (med and lat branches) near sternum. Also give off rami communicantes and
collateral branches; collateral branches run along upper border of rib below
Post rami: supply joint, skin and muscles of back
NB: T1 gives sup branch to brachial plexus; 1st and 2nd IC nerves not in costal groove, but on in surface of
ribs; 1st IC often doesn’t have ant or lat cut branches; 2nd IC nerve gives rise to large lat cut branch
Intercostobrachial nerve and supplies axilla; 7-11th IC nerves form thoracoabdominal nerves
Arteries of Thoracic Wall
Thoracic Aorta:
 Subclavian
 Internal Thoracic: passes behind and just lat to sternum, divides
into epigastric and musculophrenic arteries at 6th IC space; crossed
near origins by phrenic nerve; runs ant to transverse thoracic muscle
 Anterior Intercostals: from internal thoracic (IC spaces
1-6, from subclavian) and musculophrenic arteries (IC
spaces 7-9, from in thoracic); are paired; separated from
parietal pleura by transverse thoracic muscle; supply IC’s,
breast, skin, pecs; do not occur in lowest 2 IC spaces
 Supreme Intercostal
 Posterior Intercostals (IC spaces 1+2)
 Posterior Intercostals: R have longer course, pass post to oesophagus,
thoracic duct, azygous vein; give off post branch which supplies spinal cord,
vertebral column, back muscles and skin
 Subcostal
Continuation of subclavian  Axillary
 Superior Thoracic
 Lateral Thoracic
Factoid: thoracoepigastric vein unites superior epigastric and lat thoracic veins, providing connection
between IVC and SVC
Nerves of Thoracic Wall
Post IC veins  azygous/hemiazgous venous system  SVC (except 1st IC space, enter brachiocephalic
vein directly); 2nd +3rd IC unite to form sup IC vein (R drains into azygous vein, L into brachicephalic)
Lymphatic Drainage
Above clavicles: to inf jugular LN’s
Below clavicles: to axillary LN’s (from body wall and upper limb)
Breasts
From lat border of sternum to midaxillary line, from 2 nd to 6th ribs; nipple in 4th IC space lat to MCL; bed =
pectoral fascia and fascia covering serratus anterior – covered by retromammary space (connective tissue).
Tail of Spence extends along inflate edge of pec major towards armpit. Attached to dermis by extensory
ligaments of Cooper which support mammary gland lobules. Lobules drained by lactiferous ducts which
open onto nipple after a widened lactiferous sinus where milk stored. Also contain sebaceous glands.
Blood supply:
Subclavian  internal thoracic  ant IC branches
Subclavian  medial mammary branches
Axillary  lateral thoracic
Axillary  thoracoacromial
Thoracic aorta  post IC arteries
Venous drainage: axillary and in thoracic vein
Nerve: ant and lat branches of 4th-6th IC nerves
Lymph:
Nipple, areola and lobules
 subareolar lymphatic plexus  lat breast to axillary (ant and pectoral) LN’s  clavicular (infra and
supra) LN’s  subclavian lymphatic trunk
 med breast to parasternal LN’s  bronchomediastinal lymphatic trunk
 inf breast to abdo LN’s (subdiaphragmatic inf phrenic LN)
Skin  axillary, inf deep cervical, infraclavicular, parasternal LN’s
Bronchomediastinal and subclavian trunks join to form jugular trunk 
open into junction of in jugular and subclavian vein (venous angle) 
form brachiocephalic vein
Lungs
Pleura: serous pleural sac; split into costal (covered by endothoracic
fascia), mediastinal, diaphragmatic (connected to diaphragm by
phrenicopleural fascia) and cervical (extends 2-3cm above med 1/3 of
clavicle; covered by suprapleural membrane) parts; inf to root of lung is
pulmonary ligament where visceral meets parietal pleura ant to
oesophagus; costodiaphragmatic and costomediastinal (L>R 2Y to
cardiac notch in L lung) recesses; arteries from IC, int thoracic,
musculophrenic, thymic, pericardiac and bronchial vessels
Root of lung: bronchi, bronchial vessels, pul arteries, sup and inf pul
veins, pul plexuses of nerves (sym, paraS, visceral afferent), lymphatic
vessels; surrounded by pleural sleeve / mesopneumonium (meeting of
parietal and visceral)
Apex: extends above 1st rib
NB. Lingula slides in and out of costomediastinal recess
 cardiac notch,
with lingula inf
Trachea: 9-15cm; supported by 16-20 C-shaped rings of hyaline cartilage; C6-T5; blood from
inf thyroid and bronchial arteries, lymph to post/inf deep cervical; cricoid cartilage sits at
sternal angle; carina is downward and backward projection of last cartilage; bifurcates at T4-5
moving on respiration but not swallowing behind sternal angle; elastic; blood from inf thyroid
and bronchial arteries; lymph to post/inf deep cervical; nerves vagus and recurrent laryngeal
for pain and secretomotor, sym to BV and SM
R main bronchus: wider, shorter, runs more vertically, PA lies above then infront of it; enters
lung at T5; azygous vein arches over from behind, R PA lies below in then infront of it, gives
off branches to upper lobe
L main bronchus: inf to arch of aorta, ant to thoracic aorta; enters lung at T6
 lobar bronchi  segmental bronchi  terminal bronchioles  resp bronchioles  alveolar
ducts  pulmonary alveolus
Carina lies to L of midline
R sup bronchus is epartenol bronchus
Bronchopulmonary segments: separated from adjacent segments by connective tissue septa,
each supplied by own bronchi and artery (not vein)
Sup lobe
R Lung
Apical
Posterior
Anterior
Middle lobe
Inferior lobe
Lateral
Medial
Superior
Anterior basal
Medial basal
Lateral basal
Posterior basal
Sup lobe
Inferior lobe
L lung
Apical
Posterior
Anterior
Superior
Inferior
Superior
Anterior basal
Medial basal
Lateral basal
Posterior basal
Pulmonary trunk  L+R pulmonary arteries at sternal angle 
give off 1st branch to sup lobe before entering hilum  enter
hilum  descend postlat to bronchus  divide into lobar and
segmental arteries on ant aspect of corresponding bronchus
Pulmonary veins  L atrium
Thoracic aorta  L+R (may come from post IC) bronchial
arteries  pass along post aspect of bronchi. Supply up to resp
bronchioles. Anastomose with pul arts distally.
Bronchial veins: drain more prox part of lungs, otherwise
drained by pul veins. Drain into R = azygous vein, L =
accessory hemiazyous vein/L sup IC vein
Bronchial arteries: 2 to L (from thoracic aorta), 1 to R (from
either thoracic aorta or superior bronchial artery on L side)
Lymph:
Superficial lymphatic plexus lies deep to visceral pleura and drains lung parenchyma and visceral pleura 
bronchopulmonary LN’s  sup and inf tracheobronchial LN’s (sup and inf to bifurcation of trachea and
bronchi respectively)  R+L bronchomediastinal lymph trunks  terminate at venous angle (R may form
lymphatic duct first, L may terminate in thoracic duct)
Deep lymphatic plexus lies in submucosa of bronchi  pulmonary LN’s  bronchopulmonary LN’s
Lymph from parietal pleura drains into intercostal, parasternal, mediastinal and phrenic LN’s
Nerves: from pul plexuses ant and post to roots of lungs
Paras: vagus nerve  bronchoconstriction, vasoD, secretomotor
Provide reflexive visceral afferent fibres – cough reflex, stretch reception, Hering-Bruer
reflexes, pressor receptors, chemoreceptors
Provide nociceptive impulses for trachea
Sym: sympathetic trunk  bronchiD, vasoC, decr secretion
Provide nociceptive impulses for visceral pleura and bronchi
Pleura supplied by IC nerves (mediastinal by phrenic)
Sternal line of pleural reflection
Meet at sternal angle (2), diverge at 4, R is parasternal at 6, MCL
8, MAL 10, 12 posteriorly (@ lat border erector spinae, under
12th costoverterbal angle) – all these are 2 levels inf to actual
lung.
Oblique fissure from spinous process of T3  6th CC
Horizontal fissure from 4th rib anteriorly to 5th rib in MAL
Factoid: RUL bronchi and blood supply separate from ML and
LL prior to entering lung
Mediastinum
Arch of aorta
Bifurcation of trachea
Central tendon of
diaphragm
Lying
Sup to transverse thoracic plane
At transverse thoracic plane
Xiphisternal junction / T9
Standing
At transverse thoracic plane
Inf to transverse thoracic plane
Middle of xiphoid process / T9-10
IV disc
Superior: From sup thoracic aperture to sternal angle/IV disc of T4-5
(transverse thoracic plane)
Inferior: to diaphragm; T5-12; subdivided into ant, middle (ie.
Pericardium) and post parts by pericardium
Posterior: contains thoracic aorta, thoracic duct, lymphatic trunks,
post mediastinal LN’s, azygous and hemizygous veins, oesophagus,
oesophageal nerve plexus
Anterior: between sternum and pericardium; continuous with sup
mediastinum at sternal angle; contains connective tissue, fat,
lymphatic vessels, LN’s, branches of in thoracic vessels
Thymus: Primary lymphoid;
Post to Manubrium
Arterial supply: ant IC and ant mediastinal branches of in
thoracic arteries
Venous drainage: to L brachiocephalic, in thoracic, inf
thyroid veins
Lymph: parasternal, brachiocephalic, tracheobronchial
Trachea: ant to oesophagus; slightly to R of midline; divides at sternal
angle; terminates sup to heart; not component of post mediastinum;
bifurcates at lower limit of sup mediastinum
Oesophagus: lies to R of AofA  post to pericardium and RA and
LA  deviates to L to pass through hiatus at T10 ant to aorta with ant
and post vagal trunks, oesophageal branches of L gastric, lymphatic
vessels; has 3 compressions – by AofA, L main bronchus, and
diaphragm; thoracic duct lies to L, deep to AofA; nerve supply vagus
(via recurrent laryngeal); blood from inf thyroid, aortic branches and
L gastric (going downwards); lymph to deep cervical, mediastinal,
gastric (going downwards); lower border of cricopharyngeus muscles
is narrowest part of oesophagus, NOT DIAPHRAGM
Thoracic duct: originates in chyle cistern @ L2, to R of aorta 
ascends through aortic hiatus  ascends through post mediastinum
AA: 2.5cm wide, 5cm long; only branches are coronary
arteries from sinuses; intrapericardial; in middle
mediastinus (INF to transverse thoracic plane)
AofA: begins post to 2nd R sternocostal joint @ level of
sternal angle, post to R auricle and PA  ascends ant to
pul art and bifurcation of trachea to upper 2nd R CC, post
to pericardium and R pleura  passes over root of L 
descends post to root of lung, on L of T4; ; ligamentum
arteriosum (remnant of fetal ductus arteriosus) from root of
L pul art to inf surface of AofA lung
Note L phrenic and L vagus nerves in relation to L side of
AofA; NB. Recurrent branch of L vagus; phrenic and
vagus are separated by highest L intercostal vein
Thoracic aorta: from post to 2nd L sternocostal jt, at L inf
border T4  post to root L lung  inf border T12 enters
border through aortic hiatus; displaces oesophagus to R;
surrounded by thoracic aortic plexus; thoracic duct and
azygous vein on R side pass through aortic hiatus with it
Branches: ant, unpaired, visceral: oesophageal
Lat, paired, visceral: bronchial (R often come
from 3rd R post IC artery)
Postlat, paired, parietal – post IC arteries
Also: sup phrenic, pericardial
Brachiocephalic trunk: arises @ upper border R 2nd CC; ant to trachea, post to L BC vein, sternohyoid and
sternothryoid; ascends on R of trachea  R common carotid and subclavian; gives off thyroidea ima artery
NB. R phrenic nerve lies on R
L common carotid: arises post to Manubrium, post and to L of BC trunk  ant to L subclavian, to L of
trachea  passes post to L SC joint; no branches in mediastinum
L subclavian: arises from post AofA, post L common carotid  passes post to L SC joint
Brachiocephalic vein: formed by union of subclavian and in jugular veins @ level of 1 st CC; L >2x longer
than R;
R: R phrenic nerve on R of R brachiocephalic vein; branches include R vertebral, R in thoracic and R inf
thyroid veins;
L: passes ANTERIOR to roots coming from aorta; begin behind sternal end of L clavicle and passes behind
Manubrium, sternohyoid and sternothyroid; branches include L vertebral, L in thoracic, L inf thyroid and L
highest IC veins
SVC: returns blood from all structures sup to diaphragm except lungs and heart; enters RA at 3 rd CC; lies
antlat to trachea, postlat to ascending aorta; passes from sup to middle mediastinum; forms post boundary
of transverse pericardial sinus; behind are root of R lung and R vagus nerve; receives azygous vein before
piercing pericardium
Azygous vein: drains back, mediastinal viscera and thoracoabdominal walls; begins opposite 1st-2nd lumbar
vertebra by a branch from ascending lumbar/R renal/IVC  passes through aortic hiatus  passes on R
side of bodies of inf 8 thoracic vertebrae  arches over sup aspect of roof of R lung to join SVC; receives
R subcostal and IC, hemiazygous, oesophageal, mediastinal and pericardial veins
Hemiazygous vein: begins on L side in L ascending lumbar/renal vein  enters thorax through L crus 
ascends on L side vertebral column post to thoracic aorta to T9  crosses to R, post to aorta, thoracic duct
and oesophagus  joins azygous vein; receives inf 3 post IC, inf oesophageal veins
Vagus: descend postlat to common carotids  enters sup
mediastinum post to SC joint and BC vein  pass POST to roots of
lungs
R: passes ant to R subclavian artery  passes postinf on R of trachea
 post to R BC vein, SVC and root of R lung  branches contribute
to R pul plexus  passes to oesophagus, forming oesophageal and
deep cardiac plexus
Gives rise to R recurrent laryngeal nerve which hooks under
R subclavian artery  ascends between trachea and
oesophagus
L: enters mediastinum between L common carotid and L subclavian
 passes post to AofA and root of L lung  branches contribute to
pul plexus  oesophageal nerve plexus
Gives rise to L recurrent laryngeal nerve which hooks under
AofA lat to ligamentum arteriosum  ascends in groove
between trachea and oesophagus
Phrenic: enter sup mediastinum between subclavian artery and origin
of BC vein  pass ANT to roots of lungs
R: along R of BC vein, SVC and pericardium  over RA  descends
on R of IVC to diaphragm  pierces near caval opening
L: crosses L surface of AofA ant to L vagus  passes over L sup IC
vein  descends ant to root superficial to LA and LV  pierces
diaphragm
Post mediastinal LN’s: post to pericardium and oesophagus; receive lymph from oesophagus, post
pericardium and diaphragm, middle post IC spaces;  R lymphatic/thoracic duct
Thoracic sym trunks: lie against heads of ribs then Costovertebral joints then sides of vertebral bodies.
Pericardium
Fibrous pericardium is continuous with central tendon of diaphragm, tunica adventitia of great vessels
(except IVC) at level of Manubriosternal joint; attached anteriorly to post surface of sternum by sup and inf
sternopericardial ligaments (attach to Manubrium and xiphoid process) in L lower area of sternum and CC,
otherwise covered anteriorly by pleura, posteriorly by loose connective tissue; lined with parietal layer;
under this is visceral layer = epicardium; note IVC receives no covering from this layer; no adherent
parietal pleura posteriorly where oesophagus contacts
Aorta and pul artery are enclosed in arterial mesocardium; SVC, IVC and 4 pul veins enclosed in venous
mesocardium. Between these is Oblique pericardial sinus: reflection of serous pericardium around great
veins (permits pulsation of LA); and Transverse pericardial sinus: between aorta + pulmonary trunk /
SVC, IVC, pul veins
Artery: in thoracic  pericardiacophrenic artery (accompanies phrenic nerve down lat side heart)
 musculophrenic artery (in thoracic)
thoracic aorta  bronchial, oesophageal, sup phrenic arteries
Venous: pericardiacophrenic vein  brachiocephalic vein
Nerve: phrenic (pain), vagus, sympathetic trunk (vasomotor); visceral layer has no nerve supply
Heart and Great Vessels
Endocardium: endothelium and subendothelial connective
tissue
Myocardium: double helical orientation of fibres; outer spiral
contracts to eject blood from ventricles; anchored to fibrous
skeleton of heart forming 4 fibrous rings that surround valves;
acts as insulator to ensure atria and ventricles contract
separately
Epicardium: mesothelium, formed by visceral pericardium
Relations: anterior: sternum, CC’s, ant 3rd-5th ribs
TURN HEAD TO L THEN UP A BIT – that’s how heart lies
Ventricles separated by ant and post IV grooves
Atria and ventricles separated by coronary / AV groove
Base of heart is posterior aspect facing T6-9, is mostly L
atrium; bounded below by coronary sulcus, above with
bifurcation of pul artery; LV not involved
Ant surface is mainly RV, upper by RA, strip of LV
Diaphragmatic surface is 2/3 LV 1/3 RV, rests upon central
tendon and L muscular diaphragm
L border: LV and L auricle
R border: RA only
RA: R auricle increases capacity; smooth thin-walled post
area (sinus venarum) on which SVC (@levels of 3 rd CC,
has no valve), IVC (@level of 5th CC, has a valve) and
coronary sinus (between AV orifice and IVC, has a valve)
open; muscular ant wall of pectinate muscles – 2 areas
separated exteriorly by sulcus terminalis and interiorly by
crista terminalis, separates SVC and R auricle; fossa ovalis
on interatrial septum is remnant of oval foramen
RV: tapers into conus arteriosus  pulmonary trunk;
separated by supraventricular crest (directs flow towards
pul trunk) from irregular muscular elevations (trabeculae
carneae);
Septomarginal trabeculae: muscular bundle from inf IVS
of RV to base of ant papillary muscle, carries R branch of
AV bundle
LA: R+L (2 of each) pulmonary veins are valveless and enter post wall; wall of L auricle contains pectinate
muscles; smooth walled apart from the auricle; semilunar depression is on other side of fossa ovalis,
surrounding ridge is valve of oval fossa
LV: walls mostly covered with trabeculae carnae (finer and more than R), conical cavity is longer than R,
papillary muscles are larger than R; aortic vestibule leads to aortic orifice and valve; mitral valve has 2
cusps (ant and post) @ 4th CC which are smaller and thicker than tricuspid
Ventricular septum: mostly muscular, but upper post part is membranous
Tricuspid valve: at 4th-5th IC space; tendinous cords attach to free and ventricular edges of 3 cusps (anterior,
posterior, septal/medial), arise from papillary muscles (anterior, attached to ant and post cusps; and
posterior, attached to post and medial cusps)
Mitral valve: 2 triangular cusps; larger and thicker than tricuspid; larger anterior, smaller posterior
Semilunar valves: do not have tendinous cords; edge of each cusp is thickened (lunule), apex is thickened
further at nodule
Pulmonary valve: 3 cusps: anterior, R, L
Aortic valve: 3 cusps, posterior, R, L; larger, thicker and stronger than pulmonary
Coronary arteries: travel just deep to epicardium; supply myocardium and
epicardium
R arises from R aortic sinus (beginning of aorta), L arises from L aortic
sinus  pass around pulmonary trunk;
90% are R dominant
RCA: supplies RA, RV, some LV, some IV septum, SAN and AVN
Runs in coronary (AV) groove
 sinoatrial nodal branch (60%): supplies SAN and pul
trunk
 R marginal branch: supplies RV and apex
Continues to post side of heart
 AVN branch
 post IV branch (branches from circumflex in 15%; in
post IV groove, supplies both V’s)
LCA: supplies LA, LV, some RV, most IV septum
Runs in coronary groove  divides into
1) Circumflex branch – follows coronary groove to post surface of
heart; supplies LA and LV
 L marginal branch (supplies LV)
2) L ant descending IV branch – passes along IV groove to apex;
anastomosis with post IV branch in post heart; supplies both
ventricles and IV septum
 lat (diagonal) branch
Coronary sinus: runs from L to R in post coronary groove; receives great,
middle and small cardiac veins, L post ventricular and L marginal veins
Great cardiac: ascends in IV groove; drains areas supplied by LCA
Middle and small cardiac: drain areas supplied by RCA
Oblique vein: remnant of fetal L SVC
Small ant veins: don’t drain into coronary sinus, drain into RA
Lymph: pass to subepicardial lymphatic plexus  through coronary
groove  inf tracheobronchial LN’s (usually on R)
Conducting system:
SAN: located deep to epicardium at junction of SVC and RA, near sup end
of sulcus terminalis; supplied by SAN artery usually from RCA
AVN: in postinf interatrial septum near opening of coronary sinus;
supplied by AVN artery, from RCA in 80%
AV bundle: transmits through fibrous skeleton of heart along membranous
part of IVS; supplied by LCA
Bundles of His: divide at junction of membranous and muscular septum;
proceed on each side of muscular IVS deep to endocardium
Subendocardial branches (Purkinje fibres): extend to ventricles
RBB: to IVS, RV wall, ant papillary muscle, goes through septomarginal
trabeculae (moderator band)
LBB: 6 branches; to IVS, ant and post papillary muscles, wall of LV
Nerve supply: cardiac plexus (superficial beneath AofA, deep between AofA and bifurcation
of trachea and to R of ligamentum arteriosum) and pul trunk; deep is larger than superficial;
receives vagal input
Sym: cardiopulmonary splanchnic nerves (pain fibres accompany)
ParaS: vagus
Surface markings:
Sup border: from inf border of 2 nd L CC to sup border 3rd R CC
R border: from 3rd R CC to 6th R CC
Inf border: to 5th IC space near MCL
Aortic: at 3rd rib L sternal border  auscultate at 2nd ICS L parasternal
Pulmonary: 2nd ICS R parasternal
Tricuspid: at top of xiphoid process  auscultate at 5th L ICS
Mitral: at 4th rib L sternal border  auscultate at 5th L ICS, 6-10cm from AML