The wall of the heart is mainly composed of cardiac muscle tissue , called the myocardium, which forms the thick, middle layer responsible for pumping blood.

Quick Scoop

  • The heart wall has three layers:
    • Inner endocardium (thin smooth lining of chambers and valves).
* Middle myocardium (thick layer of cardiac muscle that contracts to pump blood).

* Outer epicardium (thin outer layer, part of the pericardium, containing vessels and connective tissue).
  • When people ask what the wall of the heart is “mainly composed of,” they almost always mean the myocardium , because it is the thickest and functionally most important layer for contraction.

So, the best direct answer: the heart wall is mainly composed of myocardium , a specialized cardiac muscle layer.