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

Diaphragm

Superior mediastinum

Posterior mediastinumMiddle mediastinum

Anterior mediastinum

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…Pulmonary trunk

Pulmonary artery

Arch of the aorta

SVC

IVC

RA

RV

LV

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?

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 valveTricuspid valve

Atrioventricular valves Name the AV valves. Where are they located?

How are they anchored to the ventricle wall?

What may be the consequences of damage to the papillary muscles?

Mitral (left ventricle) and tricuspid (right ventricle). Located between the atria and the ventricles

By tendons (chordae tendineae), which are attached to papillary muscles

Valve incompetence and cardiac murmur → mitral/tricuspid regurgitation

Semilunar valves Name the semilunar valves. Where are they located?

•During systole the cusps are pushed TOWARD the vessel walls

•During diastole blood catches in the pockets and CLOSES the valve

RP

A

LP P

RA

LA Anterior

Posterior

Pulmonary valveAortic valve

What happens to the valve cusps during systole/diastole?

Aortic (left ventricle) and pulmonary (right ventricle). Located between the ventricles and the aorta/PT

Coronary arteries

Circumflex artery -Left atrium and ventricle-Continues as posterior intraventricular in 40%-Provides AV nodal branch in 20%

Posterior interventricular artery-Posterior ⅓ of septum-AVN in 80%

Anterior interventricular artery -R & L ventricles-Majority of septum anterior ⅔-AVN in 20%

SAN artery-SAN-R & L atria-65% from RCA,35% from circumflex

RCA

LCA

RCA is dominant (gives off PIVA) in 60%

LCA is dominant in 40%

RCA is dominant (gives off PIVA) in 60%

LCA is dominant in 40%

Label...

What is the surface anatomy of the heart borders?

3rd R CC2nd L CC

6th R CC 5th L ICS midclavicular line

Where would you auscultate for the valves?

Mitral 5th left ICS MCL

Tricuspid4/5th 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!