Lecture 3: Middle mediastinum Flashcards
What are the boundaries of middle mediastinum?
Anterior – anterior pericardium
Posterior – posterior pericardium
Lateral – mediastinal pleura
Inferior – diaphragm
Superior – transverse thoracic plane
What are the contents of the middle mediastinum?
Heart & pericardium
Ascending aorta
Pulmonary trunk & arteries
Pulmonary veins
Nerves
What are the three layers of the heart tissue?
Endocardium
Myocardium
Epicardium
What is the coronary sinus?
Major vein that brings deoxygenated blood that has supplied the heart itself back into the right atrium
What connects the valves to the heart wall?
Chordae tendinae which attach to the papillary muscle
What cusps are present on the mitral valve?
Posterior and anterior cusps
What cusps are present on the tricuspid valve?
Posterior, anterior and septal
What cusps are present on the aortic valve?
Right, left and posterior
What cusps are present on the pulmonary valve?
Right, left and anterior
What is the pericardium?
3 layered sac which heart is suspended in
Attached to the great vessels superiorly and diaphragm inferiorly
Protects heart from overfilling
Influenced by movement of the great vessels, sternum & diaphragm
What are the layers of the pericardium?
Fibrous pericardium (external)
Serous pericardium (internal)
- Parietal layer
- Visceral layer (or Epicardium)
Where is the serous fluid of the pericardium?
In the pericardial cavity between the parietal and visceral pericardium
What is the transverse sinus?
Area of the pericardial cavity located between outflow vessels of the heart (AA + PT) and inflow vessels (SVC)
Can be used in surgery to clamp the outflow of blood from the heart
What are the branches of the right coronary artery?
Sinus-atrial nodal branch
Marginal branch
Posterior inter ventricular branch
What are the branches of the left coronary artery?
Circumflex
Marginal branch of circumflex
Anterior inter ventricular branch
Diagonal branch
How do you determine dominance?
Which coronary artery gives rise to the posterior inter ventricular artery
What % of people are RCA dominant?
67%
What % of people are LCA dominant?
15%
where posterior IV artery branches from circumflex
What % of people have an accessory coronary artery?
4%
What are the 4 major cardiac veins?
Great
Middle
Small
Posterior
Where does the coronary sinus drain into?
Right atrium
Where does the electrical impulse commence?
Sinuatrial node
What is the SA node?
Collection of specialised cells at junction of SVC and right atrium
Where does the electrical impulse travel to once it has been initiated at the SA node?
Travels via internal tracts to the atrioventricular node
Where is the AV node located?
In the interatrial septum close to coronary sinus opening
What is the function of the fibrous skeleton of connective tissue in the heart?
Provides attachment for Atrioventricular and Semi-lunar valves
Forms an electrical insulator between the atria and ventricles
Where does the parasympathetic innervation of the heart arise?
From the Vagus nerve, parasympathetic fibres enter the cardiac plexus and then travel to the SA node
Where does the sympathetic innervation of the heart arise?
Sympathetic fibers from sympathetic Trunk levels T1-5 enter the cardiac plexus and then travel to the SA node
How many pulmonary veins are there?
Two veins from each side - Inferior and Superior
