The fibrous pericardium is the outermost layer of dense irregular fibrous tissue covering entire heart. Beneath it is the pericardium, a double-layered serous membrane surrounding the heart. The outer layer is the parietal pericardium, which is fused to the fibrous pericardium. The epicardium is the inner (visceral) layer of the serous pericardium. Pericardial fluid fills the space between the two layers of the pericardium (pericardial cavity). The myocardium is the middle layer of cardiac muscle tissue and makes up the bulk of the heart itself. The endocardium is a thin, smooth, inner lining layer of endothelium and connective tissue.
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