Multiple choice general knowledge science & technology What is the middle layer of the heart wall known as ? Pericardium Myocardium Atrium Pyrexia Reveal answer Fill a bubble to check yourself B Correct answer Explanation The heart wall has three layers: epicardium (outer), myocardium (middle muscular layer), and endocardium (inner). The myocardium is the thickest layer and responsible for the heart's pumping action.