Myocardium is the muscular tissue of the heart. Relationship to other layers The other tissues of the heart are: the endocardium (inner lining, effectively a specialized endothelium) the epicardium (a connective tissue layer around the heart with a serous surface. It may be considered as the inner (visceral) layer of the pericardium) Composition The myocardium is composed of specialized cardiac muscle cells with an ability not possessed by muscle tissue elsewhere in the body. Cardiac muscle,… (More on Myocardial)