The wall of the heart is composed of following three layers-

1. The endocardium is a very thin smooth layer of cells, that resembles squamous epithelium. This membrane lines the interior of the heart. The valves of the heart are formed by reinforced folds of this material.

2. The myocardium is the muscular layer of the heart.

3. The epicardium forms the thin outer layer of the heart wall and is continuous with the serous lining of the fibrous sac that encloses the heart. The pericardium is a double-walled sac containing the heart and the roots of the great vessels. The pericardial sac has two layers, a serous layer, and a fibrous layer.

──────────────────────────────────────────────────────────────────────────────────────────