Structure of Heart

Question 1

Endocardium

Answer 1

• A thin internal layer (endothelium and subendothelial connective tissue)
  or
• A lining membrane of the heart that also covers its valves.

Question 2

Myocardium

Answer 2

• A thick, helical middle layer composed
  of cardiac muscle.

Question 3

Epicardium (Visceral)

Answer 3

• A thin external layer (mesothelium)
  formed by the visceral layer of serous
  pericardium.