The wall of the heart is composed of three layers: from superficial to deep: the epicardium, myocardium, and endocardium.
The three layers in the wall of the heart:
outer epicardium
middle myocardium
inner endocardium
Outer epicardium
Visceral layer of the serous pericardium (epicardium) covers the surface of the heart
Epicardium has two layers: mesothelium and underlying supporting layer of areolar tissue
Parietal layer of the serous pericardium consists of outer dense fibrous layer and inner mesothelium
Middle myocardium
The myocardium is cardiac muscle tissue that forms atria and ventricles
Associated with cardiac muscle cells, connective tissues, blood vessels, nerves
Atrial myocardium and ventricular myocardium
Inner endocardium
The endocardium covers inner surfaces of the heart including heart valves
Composed of simple squamous epithelium which is continuous with endothelium of attached great vessels
SUMMARY
Heart wall contains three layers: visceral layer of serous pericardium (epicardium), myocardium (muscular wall of heart), and endocardium (epithelium lining inner surfaces of heart)
SUMMARY - Cardiac Muscle Tissue
Bulk of heart consists of muscular myocardium. Cardiac muscle cells are smaller than skeletal muscle cells and almost totally dependent on aerobic respiration
Cardiac muscle cells are interconnected by intercalated discs, both convey force of contraction from cell to cell and conduct action potentials. Intercalated discs join cardiac muscle cell through desmosomes, myofibrils, gap junctions. Cardiac muscle cells functions as one
SUMMARY - The Cardiac Skeleton
Internal connective tissue of heart called cardiac skeleton
Cardiac skeleton of heart functions to stabilize heart's contractile cells and valves; support muscle cells, blood vessels, and nerves; distribute forces of contraction; add strength and elasticity; physically isolate atria from ventricles
