Lecture 3: Middle mediastinum

Question 1

What are the boundaries of middle mediastinum?

Answer 1

Anterior – anterior pericardium

Posterior – posterior pericardium

Lateral – mediastinal pleura

Inferior – diaphragm

Superior – transverse thoracic plane

Question 2

What are the contents of the middle mediastinum?

Answer 2

Heart & pericardium

Ascending aorta

Pulmonary trunk & arteries

Pulmonary veins
Nerves

Question 3

What are the three layers of the heart tissue?

Answer 3

Endocardium
Myocardium
Epicardium

Question 4

What is the coronary sinus?

Answer 4

Major vein that brings deoxygenated blood that has supplied the heart itself back into the right atrium

Question 5

What connects the valves to the heart wall?

Answer 5

Chordae tendinae which attach to the papillary muscle

Question 6

What cusps are present on the mitral valve?

Answer 6

Posterior and anterior cusps

Question 7

What cusps are present on the tricuspid valve?

Answer 7

Posterior, anterior and septal

Question 8

What cusps are present on the aortic valve?

Answer 8

Right, left and posterior

Question 9

What cusps are present on the pulmonary valve?

Answer 9

Right, left and anterior

Question 10

What is the pericardium?

Answer 10

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

Question 11

What are the layers of the pericardium?

Answer 11

Fibrous pericardium (external)

Serous pericardium (internal)

• Parietal layer
• Visceral layer (or Epicardium)

Question 12

Where is the serous fluid of the pericardium?

Answer 12

In the pericardial cavity between the parietal and visceral pericardium

Question 13

What is the transverse sinus?

Answer 13

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

Question 14

What are the branches of the right coronary artery?

Answer 14

Sinus-atrial nodal branch

Marginal branch

Posterior inter ventricular branch

Question 15

What are the branches of the left coronary artery?

Answer 15

Circumflex

Marginal branch of circumflex

Anterior inter ventricular branch

Diagonal branch

Question 16

How do you determine dominance?

Answer 16

Which coronary artery gives rise to the posterior inter ventricular artery

Question 17

What % of people are RCA dominant?

Answer 17

67%

Question 18

What % of people are LCA dominant?

Answer 18

15%

where posterior IV artery branches from circumflex

Question 19

What % of people have an accessory coronary artery?

Answer 19

4%

Question 20

What are the 4 major cardiac veins?

Answer 20

Great
Middle
Small
Posterior

Question 21

Where does the coronary sinus drain into?

Answer 21

Right atrium

Question 22

Where does the electrical impulse commence?

Answer 22

Sinuatrial node

Question 23

What is the SA node?

Answer 23

Collection of specialised cells at junction of SVC and right atrium

Question 24

Where does the electrical impulse travel to once it has been initiated at the SA node?

Answer 24

Travels via internal tracts to the atrioventricular node

Question 25

Where is the AV node located?

Answer 25

In the interatrial septum close to coronary sinus opening

Question 26

What is the function of the fibrous skeleton of connective tissue in the heart?

Answer 26

Provides attachment for Atrioventricular and Semi-lunar valves

Forms an electrical insulator between the atria and ventricles

Question 27

Where does the parasympathetic innervation of the heart arise?

Answer 27

From the Vagus nerve, parasympathetic fibres enter the cardiac plexus and then travel to the SA node

Question 28

Where does the sympathetic innervation of the heart arise?

Answer 28

Sympathetic fibers from sympathetic Trunk levels T1-5 enter the cardiac plexus and then travel to the SA node

Question 29

How many pulmonary veins are there?

Answer 29

Two veins from each side - Inferior and Superior