Multiple choice

Which part of human heart wall is made of involuntary cardiac muscle cells?

  1. Epicardium

  2. Atrium

  3. Endocardium

  4. Myocardium

  5. Intercalated discs

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

It is the thick middle layer and muscular tissue of the heart that forms the bulk of the heart wall. Specially modified fibres of myocardial muscle constitute the conduction system of the heart including the sinoatrial node, the atrioventricular (AV) node, the AV bundle, and the purkinje fibres.