Cardiovascular anatomy

Question 1

What are the 3 layers of the heart?

Answer 1

• Endocardium → innermost layer
• Myocardium → middle, muscular layer
• Epicardium → outermost layer

Question 2

What is the endocardium? Briefly describe the pathological structure.

Answer 2

Innermost layer covering the heart wall, covers the chambers and valves

• Composed of simple squamous epithelium and loose connective tissue (similar structure to blood vessel walls)

Question 3

What is the subendocardial layer? Which important structures of the heart can be found here?

Answer 3

Thin layer of connective tissue between the endocardium and the myocardium

• Contains Purkinje fibres of the conducting system

Question 4

What is the myocardium? Briefly describe the pathological structure and how this relates to its function.

Answer 4

Middle layer which forms majority of the heart wall

• Composed of involuntary striated cardiac muscle
• Contractile component of the heart responsible for generating force of contractions

Question 5

What is the epicardium? Briefly describe the pathological structure.

Answer 5

The outermost layer of the heart which forms a visceral layer of serous pericardium

• Composed of loose connective tissue and fat, lined by mesothelium

Question 5

What are the 3 main functions of the epicardium?

Answer 5

• Protection → provides a barrier between external structures
• Secretes pericardial fluid → provides lubrication in the pericardial cavity
• Reduces friction during contractions

Question 6

What are the 4 layers of the pericardium?

Answer 6

• Fibrous layer
• Parietal layer
• Serous fluid
• Visceral layer of serous (epicardium)

Question 7

What are the functions of the pericardium?

Answer 7

• Maintains position of the heart in the pericardium
• Fibrous layer → prevents heart increasing in size too fast
• Lubrication → reduces friction
• Prevents infection → physical barrier from lungs etc

Question 8

What are the 4 chambers of the heart?

Answer 8

• Right atrium → Receives blood from superior and inferior vena cava and coronary sinus
• Right ventricle → Pumps blood to the lungs via the pulmonary artery
• Left atrium → Receives blood from the pulmonary veins
• Left ventricles → Pumps blood to the body via the aorta and coronary arteries

Question 9

What are the 2 atrioventricular valves? What is their function?

Answer 9

Tricuspid and mitral valves
- Prevents backflow of blood into atria during diastole

Question 10

What are the 2 semilunar valves? What is their function?

Answer 10

Aortic and pulmonary valves
- Prevent backflow of blood into ventricles during systole

Question 11

What is the function of papillary muscles and the chordae tendinae in the heart?

Answer 11

Papillary muscles are muscular projections anchoring the chordae tendinae (fibrous cords attached to AV valves) to the ventricle walls
- Contracts to keep AV valve leaflets closed during systole

Question 12

How many valve leaflets do each of the valves have?

Answer 12

• Mitral valve → 2
• Aortic, pulmonary, tricuspid → 3

Question 13

What is an END artery?

Answer 13

Terminal artery solely responsible for blood supply to that region
- No collateral circulation if there is a blockage, leads to ischaemia and infaction

Question 14

What is an anastamosis?

Answer 14

Connections between blood vessels which allows for collateral circulation
- Provides alternative routes for blood to reach tissue, prevents ischaemia and infarction

Question 15

Why are the coronary arteries susceptible to ischaemia and infarction?

Answer 15

They are functional END arteries which means they are solely responsible for blood supply to that region
- They do have tiny anastamoses but this is not sufficient to allow for collateral circulation if there is a blockage

Question 16

Where do the coronary arteries originate from?

Answer 16

They originate from the ascending aorta just above the aortic valve cusps

• Left coronary artery originates from left aortic sinus
• Right coronary artery originates from right aortic sinus

Question 17

Describe the main coronary arteries and their overall function.

Answer 17

Left coronary artery (branches into LAD and LCx) and right coronary artery

• Blood supply to the myocardium which allows for cardiac contraction

Question 18

What are the 3 main branches of the left coronary artery?

Answer 18

• Left anterior descending artery (anterior interventricular)
• Left circumflex artery
• Ramus intermedius (sometimes present)

Question 19

What regions of the heart does the LAD artery supply?

Answer 19

• Anterior wall of left ventricle
• Anterior 2/3 of interventricular septum
• Apex of heart

Question 20

What are the branches of the LAD artery?

Answer 20

• Septal perforating arteries
• Diagonal branches

Question 21

What regions of the heart does the LCx artery supply?

Answer 21

Lateral and posterior walls of left ventricle

Question 22

What are the branches of the LCx artery?

Answer 22

• Obtuse marginal branches
• Postero-lateral branches (left-dominant hearts)

Question 23

What regions of the heart does the RCA supply?

Answer 23

• Right atrium and right ventricle
• Inferior wall of left ventricle
• Posterior 1/3 of interventricular septum
• SA node and AV node

Question 24

What are the main branches of the RCA?

Answer 24

- Posterior descending artery - Right marginal artery - AV and SA nodal arteries

Question 25

What does heart dominance mean? Which side of the heart is most commonly dominant?

Answer 25

Dominance refers to the coronary artery that gives rise to the PDA - Right dominance (RCA) → 70-85% - Left dominance (LCx) → 10-15% - Co-dominance → 5-10%