Answer:
Endocardium: is the innermost layer of the heart.
Myocardium: is the muscle layer
Pericardium: is a double-wall sac that cointains the heart.
Step-by-step explanation:
While the Pericardium protects the heart against infection, provides lubrication and fixes it to the mediastinum, the Myocardium is the middle layer from the heart and the thickest one. It has specialized muscle fibers that carry electrical impulses to the ventricles. It is the muscle layer comprised of cardiomyocytes. The endocardium is comprised of two layers: the inner one is made of endothelial cells and the second one is a subendocardial connective tissue where branches of the heart's conduction system are inmersed.