Endocardium

The endocardium (inner layer; tunica intima) lines the heart cavity, is in contact with the flowing blood, smoothly passes into the tunic of the vascular intima, forms the heart valves. It consists of 4 layers:
 * 1) endothelium (endothelial cells);
 * 2) subendothelium (collagen ligament);
 * 3) elastic-muscular layer (collagen and elastic ligament, smooth muscle cells; this layer is especially strong in the atria);
 * 4) subendocardium (a sparse connective tissue found here in the structure of the cardiac conduction system).

Related articles

 * Heart
 * Heart/histology
 * Cardiac conduction system