2. Anatomy of the Heart & Coronary Vessels

Question 1

What are the 4 functions of the pericardium?

Answer 1

Fixes heart in mediastinum

Protection from infections from other organs

Prevents excessive heart dilation

Lubrication

Question 2

What is this?

Answer 2

Pericardial effusion leading to pericardial tamponade

Question 3

Give 3 factors leading to cardiac tamponade.

Answer 3

1. rate of accumulation
2. fluid amount in pericardium
3. compliance of pericardium

Question 4

How can cardiac tamponade lead to MI?

Answer 4

CT from e.g. fluid amount in pericardium/accumulation rate -> increase in volume compresses atria, vena cava and pulmonary veins -> R ventricle collapse

OR

CT from e.g. fluid amount in pericardium/accumulation rate -> decreased R. ventricle filling in diastole, stroke volume and C.O.

Question 5

What are A, B, C, D and E?

Answer 5

A: Endocardium

B: Myocardium

C: Epicardium

D: Atrioventricular valve

E: Branch of the coronary artery

Question 6

Describe the flow of blood through the heart.

Answer 6

SVC, IVC, Coronary sinus -> R. atrium -> (tricuspid valve) -> R. ventricle -> (pulmonary semi lunar valve) -> pulmonary trunk -> pulmonary arteries to lungs -> pulmonary capillaries -> 4 pulmonary veins -> L. atrium -> (mitral valve) -> L. ventricle -> (aortic semi lunar valve) -> aorta -> (body) -> systemic capillaries -> veins -> heart

Question 7

What is the coronary groove (atrioventricular sulcus)?

Answer 7

Oblique plane which seperates atria and ventricles

Question 8

What are the (ant. and post.) interventricular grooves?

Answer 8

Overlie intervetricular septum which seperates L and R ventricles

Question 9

Give 2 features of the R. ventricle.

Give 3 features of the L. ventricle.

Answer 9

R. ventricle: 2/3 anterior, pulmonary trunk

L. ventricle: apex (L. border), inferior surface (2/3 posterior), aorta

Question 10

What are A, B, C, D and E?

Answer 10

A: R. atrium

B: R. ventricle

C: L. ventricle

D: Pulmonary trunk

E: ligamentim arteriosum

Question 11

What are A - G?

Answer 11

A: auricle of LA

B: L ventricle

C: coronary sinus

D: PIG (post. interventricular groove)

E: R. ventricle

F: L. atrium

G: L pulmonary arteries

Question 12

What are A-F?

Answer 12

A: coronary sinus

B: fossa ovalis

C: tricuspid valve

D: chordae tendinae

E: papillary muscles

F: trabeculae carnae

Question 13

What are A-F?

Answer 13

A: SVC

B: fossa ovalis

C: IVC

D: coronary sinus

E: tricuspid valve

F: pectinate muscle

Question 14

Where are the R. atrium and ventricle in relation to the L. atrium and ventricle?

Answer 14

R: right border and anterior surface

L: posterior or base of heart (plus thicker myocardium)

Question 15

Label the coronary blood supply

Answer 15

A: L. coronary artery

B: R. coronary artery

C: mitral valve

Question 16

Describe the coronoray artery supply.

Answer 16

RCA gives rise to post. interventricular artery and then anastomoses with circumflex branch of LCA

Anterior interventricular (LAD) loops around apex and anastamoses with post. interventricular artery

Question 17

What are A-C?

Answer 17

A: Left Coronary Artery

B: L. circumflex

C: Anterior interventricular (LAD)

Question 18

What coronary arteries are usually the cause of MI?

Answer 18

LAD (ant. interventricular) of LCA (40-50%)

RCA (30-40%)

LCA circumflex (15-20%)

Question 19

What branches of coronary arteries supply AVN and SAN?

Answer 19

AVN: RCA & LAD

SAN: RCA

Question 20

What is the path of coronary veins?

Answer 20

Collect waste from cardiac muscle -> drain to coronary sinus on post. heart -> R. atrium

Question 21

The dense CT fibrous skeleton of the heart surrounds AV and outflow vessel valves. It merges with the interventricular septum. What are its 4 main functions?

Answer 21

1. support valves
2. prevent overstretching of valves
3. insertion point of cardiac muscle bundles
4. electrical insulator between atria and ventricles

Question 22

What do valves do in diastole?

Answer 22

AV valves open. blood flows A -> V when vent. pressre < atrial pressure.

Chordae tendinae slack, papillary muscles relaxed.

SL valves closed.

Question 23

What do the valves do in systole?

Answer 23

AV valves close preventing backflow (when vent. contract, pushes valve cusps closed).

Chordae tendinae taut, papillary muscles contract to pull chords.

Sl valves open.

Question 24

How many cusps do semilunar valves have, and what are they?

Answer 24

1. L coronary aortic sinus
2. R. coronary aortic sinus
3. Non-coronary aortic sinus

Question 25

Describe the conduction system of the heart

Answer 25

SAN (pacemaker cells) impulses contract atria **-\>** impulses pause 0.1s at AVN so ventricles fill **-\>** AV bundle connects A & V **-\>** AVN branches conduct impulse through interventricular septum **-\>** purkinje fibres stimulate contractile cells of both ventricles, start at apex and move up

Question 26

The heart is innervated by the cardiac plexus of nerves. Where it is located, and what does it contain? It extends to coronary vasculature and components fo conducting system.

Answer 26

1. Anterior to carina and posterior to aortic arch 2. parasympathetic from vagus, sympathetic (from sympathetic trunk), visceral general afferents (VGA)

Question 27

What is the path for cardiac sympathetic innervation?

Answer 27

Cardioacceleratory centre in medullary retiuclar formation Preganglionic sympathetic neurons in thoracic spinal cord Postganglionis sympathetic neurons to SAN, AVN and coronary vascular SM Increase HT and contraction force

Question 28

What is the path for cardiac parasympathetic innervation?

Answer 28

Cardioinhibitory centre in reticular formation in medulla Vagus nerve to SAN and AVN Slows HR

Question 29

Pain is not felt in the heart - **referred pain.** Descrive the path of pain caused by ischaemia and damage to cardiac muscle.

Answer 29

Stimuates visceral sensory nerve endings in myocardium -\> afferent ascends to CNS through cardiac branches of sympathetic trunk -\> (organ and skin pain fibres travel together) -\> interpreted as it if came from somatic areas e.g skin supplied by **T1-5 L side of chest, neck, face and L. arm**. Infarct on **inferior** wall referred to epigastrium **T7-9**.