Heart and mediastinum

Mediastinum

What is the mediastinum? The region between the lungs, extending from the thoracic inlet to the diaphragm

Label… Rib 1 Sternal angle @ T4/5 Superior mediastinum Anterior mediastinum Middle mediastinum Posterior mediastinum Posterior mediastinum extends inferiorly to the 12th thoracic vertebrae (costodiaphragmatic recess) Diaphragm

Contents of the mediastinum Superior Thymus, trachea, oesophagus, aortic arch, SVC, thoracic duct, phrenic & vagus nerves Anterior Lymph nodes, thymus (in children), internal thoracic vessels Middle Pericardium, heart, ascending aorta, tracheal bifurcation, pulmonary artery, SVC Posterior Thoracic part of the descending aorta, azygous vein, splanchnic nerves, sympathetic chain, oesophagus and thoracic duct

Heart

Label… Arch of the aorta SVC Pulmonary artery Pulmonary trunk RA RV LV Which structures of the heart sit anteriorly and which sit posteriorly? Right anterior, left posterior Why? This is because, during development, the heart is a midline structure that rotates to the left IVC Apex

What are the three layers of pericardium? Fibrous pericardium – what are its attachments? Parietal layer of the serous pericardium Visceral layer of the serous pericardium What can be used to clamp arterial outflow during cardiac surgery? Between which layers would a ruptured coronary artery/ventricle/atrium bleed? What could this cause -> in the pericardial cavity (between parietal and visceral layers). Could cause cardiac tamponade. Fibrous pericardium is attached inferiorly to the central tendon of the diaphragm, hence why it moves inferiorly during inspiration. Also attached anteriorly to the sternum by the sternopericardial ligaments. Its apex is continuous with the adventitia of the great vessels Transverse pericardial sinus = a passage between two sites of reflected serous pericardium, separating the arteries from the veins

What is the function of the fibrous skeleton? Prevents free conduction of electrical signals from the atria to the ventricles → AVN only route for signal conduction Also provides structure and support for the heart → it is an attachment point for the AV valves Mitral valve Tricuspid valve Can anyone know what is being shown on this diagram?

Atrioventricular valves Name the AV valves. Where are they located? Mitral (left ventricle) and tricuspid (right ventricle). Located between the atria and the ventricles How are they anchored to the ventricle wall? By tendons (chordae tendineae), which are attached to papillary muscles What may be the consequences of damage to the papillary muscles? Valve incompetence and cardiac murmur → mitral/tricuspid regurgitation

Semilunar valves Name the semilunar valves. Where are they located? Aortic (left ventricle) and pulmonary (right ventricle). Located between the ventricles and the aorta/PT What happens to the valve cusps during systole/diastole? Posterior RP A LP During systole the cusps are pushed TOWARD the vessel walls During diastole blood catches in the pockets and CLOSES the valve How many cusps are the semilunar valves made of? How are the cusps named? (if this is posterior and this is anterior?) P RA LA Aortic valve Anterior Pulmonary valve

Coronary arteries LCA RCA SAN artery SAN R & L atria 65% from RCA,35% from circumflex Circumflex artery Left atrium and ventricle Continues as posterior intraventricular in 40% Provides AV nodal branch in 20% LCA Anterior interventricular artery R & L ventricles Majority of septum anterior ⅔ AVN in 20% RCA Posterior interventricular artery Posterior ⅓ of septum AVN in 80% RCA is dominant (gives off PIVA) in 60% LCA is dominant in 40%

Label...

What is the surface anatomy of the heart borders? 2nd L CC 3rd R CC 5th L ICS midclavicular line 6th R CC

Where would you auscultate for the valves? Mitral 5th left ICS MCL Tricuspid 4/5th left ICS Pulmonary 2nd left ICS Aortic 2nd right ICS

Thanks! Feel free to email us at ami.mason@warwick.ac.uk or Annabel.fothergill@warwick.ac.uk if you have any questions!