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Cardiac Anatomy QUB CardioSoc Teaching Series #1 James Cartlidge Intercalating Student wcartlidge02@qub.ac.uk Overview • Mediastinum (Middle) • Pericardium • Heart Borders and Surface Landmarks • Heart Wall Composition • Ca• Chambershology • Valves • Ca• Coronary Arteries • Coronary Veins • Great Vessels • Cardiac Conduction SystemMediastinum (Middle) • Central compartment of thoracic cavity • Mediastinum divided into 2 parts – plane from sternal angle to T4 • Superior: extends upward, terminating at superior thoracic aperture • Inferior: extends downwards, terminating at diaphragm • Anterior, middle, posterior • Middle mediastinum borders • Anterior: anterior pericardium • Posterior: posterior pericardium • Laterally: mediastinal pleurae • Superiorly: sternal angle to T4 plane • Inferiorly: superior diaphragmatic surfaceMediastinum (Middle) • Organs • Heart, pericardium, tracheal bifurcation (L&R main bronchi) • Vessels • Ascending aorta • Pulmonary trunk: short & wide → L&R pulmonary arteries • Superior vena cava: union of R&L brachiocephalic veins • Nerves • Cardiac plexus: sympathetic (T1-T4) & parasympathetic (vagus) fibres • Phrenic nerves (L&R): mixed nerves, motor innervation to diaphragm • Lymphatics • Tracheobronchial lymph nodes Mediastinum Thieme Atlas of Anatomy, 4 Edition TeachMe Anatomy https://teachmeanatomy.infoPericardium • Fibro-serous, fluid-filled sac: 2 main layers • Surrounds heart & great vessel roots • Fibrous pericardium (tough external layer) • Tough connective tissue, relatively non-distensible, rigid structure • Serous pericardium • Enclosed within fibrous pericardium: 2 layers, mesothelium • Outer parietal: lines internal surface of fibrous pericardium • Internal visceral: outer layer of heart (epicardium) • Pericardial cavity: serous fluid present between layersPericardium • Functions • Fixes heart in mediastinum, limiting motion: diaphragm (pericardiophrenic), sternum (sternopericardial), great vessels (tunica adventitia) • Prevents overfilling: fibrous pericardium • Lubrication: serous fluid in pericardial cavity • Protection from infection: physical barrier • Innervation • Phrenic nerve (C3-C5): somatic innervation (sensorimotor to diaphragm) • Source of referred pain (e.g., shoulder pain) Pericardium Thieme Atlas of Anatomy, 4 Edition Moore’s Clinically Oriented Anatomy, 7 EditionHeart Borders & Surface Landmarks • Complex pyramidal shape, apex points anteroinferior (oblique) • 5 heart surfaces • Anterior (sternocostal): right ventricle • Posterior (base): left atrium • Inferior (diaphragmatic): L & R ventricles • Right pulmonary: right atrium • Left pulmonary: left ventricle • 4 main borders • Right: right atrium (3 CC – 6 CC)h nd th • Left: left ventricle (some of left atrium) (2 CC – 5 ICS MCL) • Superior: R & L atria, great vessels • Inferior: L & R ventricles Heart Borders & Surface Landmarks • 3 main sulci (grooves) • Coronary sulcus (atrioventricular groove) • Circles around, separation of atria from ventricles • Contains RCA, LCx, small cardiac vein, coronary sinus • Anterior interventricular sulcus • Anterior surface, separation of ventricles • Contains LAD, great cardiac vein • Posterior interventricular sulcus • Posterior surface, separation of ventricles • Contains posterior interventricular artery, middle cardiac vein • Pericardial sinuses • Oblique pericardial sinus • Transverse pericardial sinus • Posterior to ascending aorta & pulmonary trunk, anterior to superior vena cava, superior to left atrium • Separates arterial & venous vessels, used to identify & ligate arteries during CABGHeart Borders & Surface Landmarks • Areas for optimal valve auscultation • Aortic valve: 2 ICS, right sternal edge nd • Pulmonary valve: 2 ICS, left sternal edge • Tricuspid valve: 4 ICS, lower left sternal edge • Mitral valve: 5th ICS, mid-clavicular line Thieme Atlas of Anatomy, 4 EditionHeart Borders & Surface Landmarks th Moore’s Clinically Oriented Anatomy, 7 EditionT ransverse Pericardial Sinus Moore’s Clinically Oriented Anatomy, 7 Edition TeachMe Anatomy https://teachmeanatomy.infoHeart Wall Composition • 3/4 distinct layers • Endocardium • Innermost, lines cavities & valves • Loose connective tissue & simple squamous epithelium • Subendocardial • Loose fibrous tissue, contains vessels & nerves of conduction system • Purkinje fibres, damage → arrhythmias • Myocardium • Involuntary striated muscle, responsible for contractions • Epicardium • Outermost, visceral layer of pericardiumCardiac Morphology - Chambers • 4 chambers: 2 atria, 2 ventricles – L & R • Right Atrium • Deoxygenated blood from SVC, IVC & coronary veins • Antero-medial portion: right auricle • Interior surface: 2 parts separated by crista terminalis (muscular ridge) • Sinus venarum: posterior to CT, smooth walls • Atrium proper: anterior to CT, pectinate muscle • Coronary sinus • Blood from coronary veins • Between IVC & right AV orifices • Interatrial Septum • Solid muscular wall • Fossa ovalis – remnant of foramen ovale • Atrial septal defect (PFO): left → right shuntCardiac Morphology - Chambers • Left Atrium • Oxygenated blood from 4 pulmonary veins • Superior aspect: L auricle (overlapping pulmonary trunk root) • Interior surface: 2 parts • Inflow: receives from pulmonary veins, smooth internal surface • Outflow: anterior, includes L auricle, pectinate muscles • Right Ventricle • Deoxygenated blood from RA • Inflow & outflow portions (separated by supraventricular crest) • Inflow: trabeculae carnae, papillary muscles, chordae tendineae • Outflow (conus arteriosus): superior aspect, smooth wallsCardiac Morphology - Chambers • Interventricular Septum • Superior membranous (thinner) & inferior muscular (thicker) parts • Left Ventricle • Oxygenated blood from LA • Inflow & outflow parts • Inflow: trabeculae carnae, 2 x papillary muscles • Outflow: aortic vestibule, smooth-walled • Tetralogy of Fallot • Cyanotic congenital heart disease – 4 abnormalities • Ventricular septal defect • Overriding aorta • Right ventricular hypertrophyCardiac Morphology - Chambers TeachMe Anatomy https://teachmeanatomy.infoCardiac Morphology - Chambers Moore’s Clinically Oriented Anatomy, 7 EditionCardiac Morphology - Chambers th Moore’s Clinically Oriented Anatomy, 7 EditionCardiac Morphology - Chambers TeachMe Anatomy https://teachmeanatomy.info Moore’s Clinically Oriented Anatomy, 7 EditionCardiac Morphology - Valves • 4 valves, unidirectional blood flow (connective tissue & endocardium) • Atrioventricular Valves • Between atria & ventricles, close during systole (S1) • Tricuspid (RA → RV) • 3 cusps: anterior, septal, posterior (3 x papillary muscles) • Mitral (LA → LV) • 2 cusps: anterior, posterior (2 x papillary muscles) • Semilunar Valves • Between ventricles & outflow vessels, close during diastole (S2) • Pulmonary (RV → PT/PA) • 3 cusps: left, right, anterior • Aortic (LV → Ao) • 3 cusps: right, left, posterior (non-coronary) – R & L aortic sinuses → R & L coronary arteriesCardiac Morphology - Valves TeachMe Anatomy https://teachmeanatomy.info Moore’s Clinically Oriented Anatomy, 7 EditionCardiac Morphology - Valves th Moore’s Clinically Oriented Anatomy, 7 EditionCardiac Vasculature – Coronary Arteries • L & R coronary arteries arise from L & R aortic sinuses (coronary ostia) • Diastole, blood backflow fills valve cusps, enters coronaries • Left CA (LA, LV, IVS, AV bundles) – L main stem • Left anterior descending (anterior interventricular) (RV, LV, anterior 2/3 IVS) • Left marginal (LV) • Left circumflex (10-15% LCx contributes to posterior interventricular) (LA, LV) • Right CA (RV, SA (60%) & AV (80%) nodes, PIVS) – R main stem • Right marginal (RV, apex) • Posterior interventricular (80-85%) (RV, LV, posterior 1/3 IVS) • Co-dominance: ~5%Cardiac Vasculature – Cardiac Veins • Venous drainage mostly through coronary sinus • Posterior aspect, large venous structure, empties into RA • Main coronary sinus tributaries • Great cardiac (anterior interventricular) • Largest tributary, originates at apex, ascends in anterior interventricular groove, curves L to posterior, enlarges to form coronary sinus • Middle cardiac (posterior interventricular) • Originates at apex, ascends in posterior interventricular groove, into CS • Small cardiac • Anterior surface, in right atrioventricular groove onto posterior, into CS • Posterior cardiac • Posterior of LV, situated to left of middle cardiac vein, empties into CS • Smallest cardiac (anterior) • Drains directly into RACardiac Vasculature • Anatomical location of coronary arteries & veins • L AV groove – coronary sinus – L circumflex artery • AIV groove into L AV groove – great cardiac vein – LAD • PIV groove – middle cardiac vein – PDA (PIVA) • R AV groove – small cardiac vein – RCA & R acute marginalCardiac Vasculature Thieme Atlas of Anatomy, 4 EditionMoore’s Clinically Oriented Anatomy, 7 EditionCardiac Vasculature TeachMe Anatomy https://teachmeanatomy.info Great Vessels • Aorta • Oxygenated blood, arising from aortic orifice at LV base, via aortic valve • Coronaries branch from ascending part • Aortic arch branches: brachiocephalic trunk, L common carotid, L subclavian • Pulmonary Arteries • Deoxygenated blood from RV → lungs, via pulmonary valve • Pulmonary trunk: short, thick, ~T5-T6 splits into L & R PAs • Pulmonary Veins • Oxygenated blood from lungs → LA, 4 x PVs, (superior & inferior)/lung • Superior Vena Cava • Deoxygenated blood superior to diaphragm → RA • Formed by merging of L & R brachiocephalic veins • Inferior Vena Cava • Deoxygenated blood inferior to diaphragm → RA • Formed in pelvis by union of common iliac veins, traverse diaphragm into pericardium at T8 Great Vessels TeachMe Anatomy https://teachmeanatomy.info Thieme Atlas of Anatomy, 4 EditionCardiac Conduction System • Collection of nodes & specialised conduction cells, initiate & coordinate contraction • SAN → AVN → AVB (BoH) → PFs • Sinoatrial Node • Pacemaker cells, in upper wall of RA, at junction where SVC enters • Atrioventricular Node • Atria impulses converge, located within AV septum (triangle of Koch), near CS opening, ~120ms delay • Atrioventricular Bundle (Bundle of His) • Continuation of specialized AVN tissue, descends membranous IVS, divides into R & L bundle branches • Purkinje Fibres • conduction, coordinated ventricular systoleextensive gap junctions, rapidCardiac Conduction System th Moore’s Clinically Oriented Anatomy, 7 EditionCardiac Conduction System Thieme Atlas of Anatomy, 4 EditionMCQ#1 • Which nerve roots pass through the middle mediastinum to innervate the diaphragm? A. T1-T4 B. C5-T1 C. C3-C5 D. T5-T6 E. C2-C5MCQ#1 • Which nerve roots pass through the middle mediastinum to innervate the diaphragm? A. T1-T4 B. C5-T1 C. C3-C5 (phrenic nerve) D. T5-T6 E. C2-C5MCQ#2 • In the anatomical position, which cardiac chamber forms the base of the heart? A. Right atrium B. Left atrium C. Right ventricle D. Left ventricle E. Right and left atriaMCQ#2 • In the anatomical position, which cardiac chamber forms the base of the heart? A. Right atrium B. Left atrium C. Right ventricle D. Left ventricle E. Right and left atriaMCQ#3 • How many leaflets / cusps form the mitral valve? A. 1 B. 2 C. 3 D. 4MCQ#3 • How many leaflets / cusps form the mitral valve? A. 1 B. 2 (bicuspid valve) C. 3 D. 4MCQ#4 • How many papillary muscles are present in the right ventricle? A. 1 B. 2 C. 3 D. 4MCQ#4 • How many papillary muscles are present in the right ventricle? A. 1 B. 2 C. 3 (three leaflets of tricuspid valve hence 3 x PM (anterior (arises from moderator band), medial, posterior)) D. 4MCQ#5 • What is the name of the internal structure that separates the right atrium into two parts, the sinus venarum and atrium proper? A. Crista terminalis B. Sulcus terminalis C. Fossa ovalis D. Moderator band E. Supraventricular crestMCQ#5 • What is the name of the internal structure that separates the right atrium into two parts, the sinus venarum and atrium proper? A. Crista terminalis B. Sulcus terminalis C. Fossa ovalis D. Moderator band E. Supraventricular crestMCQ#6 • The shallow depression found on the interatrial septum is a remnant of which embryonic structure? A. Bulbus cordis B. Primitive atrium C. Sinus venosus D. Ductus arteriosus E. Foramen ovaleMCQ#6 • The shallow depression found on the interatrial septum is a remnant of which embryonic structure? A. Bulbus cordis B. Primitive atrium C. Sinus venosus D. Ductus arteriosus E. Foramen ovale (in adult is the fossa ovalis)MCQ#7 • In what layer of the heart are the Purkinje fibres of the cardiac conduction system found? A. Endocardium B. Sub-endocardium C. Myocardium D. Sub-epicardium E. EpicardiumMCQ#7 • In what layer of the heart wall are the Purkinje fibres of the cardiac conduction system found? A. Endocardium B. Sub-endocardium C. Myocardium D. Sub-epicardium E. EpicardiumMCQ#8 • What pericardial sinus is used by cardiac surgeons to identify and subsequently ligate the main arterial great vessels during coronary artery bypass grafting? A. Sagittal sinus B. Longitudinal sinus C. Oblique sinus D. Transverse sinus E. Coronal sinusMCQ#8 • What pericardial sinus is used by cardiac surgeons to identify and subsequently ligate the main arterial great vessel during coronary artery bypass grafting? A. Sagittal sinus B. Longitudinal sinus C. Oblique sinus D. Transverse sinus E. Coronal sinusMCQ#9 • If an acutely unwell patient presents with ST-elevation changes in ECG leads I, aVL, V5 & V6, what specific coronary artery of theirs could you deduce is occluded? A. RCA B. LCx C. PDA D. LAD E. RMAMCQ#9 • If an acutely unwell patient presents with ST-elevation changes in ECG leads I, aVL, V5 & V6, what specific coronary artery of theirs could you deduce is occluded? A. RCA B. LCx (Anterolateral) C. PDA D. LAD E. RMAMCQ#10 • What cardiac structure generates the action potential to initiate myocardial contraction? A. Moderator band B. Bundle of His C. Sinoatrial node D. Purkinje fibres E. Atrioventricular nodeMCQ#10 • What structure generates the action potential to initiate myocardial contraction? A. Moderator band B. Bundle of His C. Sinoatrial node (Pacemaker cells) D. Purkinje fibres E. Atrioventricular nodeMCQ#11 • What is structure #2? A. Right ventricle B. Left anterior descending coronary C. Great cardiac vein D. Left ventricle E. Right marginal artery McMinn’s & Abraham’s Clinical Atlas of Human Anatomy, 7 EditionMCQ#11 • What is structure #2? A. Right ventricle B. Left anterior descending coronary C. Great cardiac vein D. Left ventricle E. Right marginal artery McMinn’s & Abraham’s Clinical Atlas of Human Anatomy, 7 EditionMCQ#12 • What is structure #2? A. Great cardiac vein B. Left circumflex coronary C. Posterior descending artery D. Coronary sinus E. Right atrium McMinn’s & Abraham’s Clinical Atlas of Human Anatomy, 7 EditionMCQ#12 • What is structure #2? A. Great cardiac vein B. Left circumflex coronary C. Posterior descending artery D. Coronary sinus E. Right atrium McMinn’s & Abraham’s Clinical Atlas of Human Anatomy, 7 EditionMCQ#13 • What is structure #3? A. Coronary sinus opening B. Crista terminalis C. Fossa ovalis D. Pectinate muscles E. Sinoatrial node position McMinn’s & Abraham’s Clinical Atlas of Human Anatomy, 7 EditionMCQ#13 • What is structure #3? A. Coronary sinus opening B. Crista terminalis C. Fossa ovalis D. Pectinate muscles E. Sinoatrial node position McMinn’s & Abraham’s Clinical Atlas of Human Anatomy, 7 EditionMCQ#14 • What is structure #4? A. Right atrial appendage B. Superior vena cava C. Right atrium D. Pulmonary trunk E. Aorta McMinn’s & Abraham’s Clinical Atlas of Human Anatomy, 7 EditionMCQ#14 • What is structure #4? A. Right atrial appendage B. Superior vena cava C. Right atrium D. Pulmonary trunk E. Aorta McMinn’s & Abraham’s Clinical Atlas of Human Anatomy, 7 EditionMCQ#15 • What is structure #9? A. Left pulmonary valve cusp B. Anterior mitral valve cusp C. Right coronary ostium D. Left coronary ostium E. Proximal aortic aneurysm McMinn’s & Abraham’s Clinical Atlas of Human Anatomy, 7 EditionMCQ#15 • What is structure #9? A. Left pulmonary valve cusp B. Anterior mitral valve cusp C. Right coronary ostium D. Left coronary ostium E. Proximal aortic aneurysm McMinn’s & Abraham’s Clinical Atlas of Human Anatomy, 7 EditionReferences / Resources • TeachMe Anatomy https://teachmeanatomy.info • PassMedicine https://www.passmedicine.com/ • Pastest https://www.pastest.com/ • Key Questions in Cardiac Surgery th • Moore’s Clinically Oriented Anatomy, 7 Edition • Thieme Atlas of Anatomy, 4 Edition • McMinn’s & Abraham’s Clinical Atlas of Human Anatomy, 7 EditionFeedback