Answer: Option D
:
D
The heart is covered by a three-layered fibroserous sac called the pericardium, similar to the pleura encasing the lungs. The outer layer of the pericardium is the fibrous pericardium, comprised of dense connective tissue, which protects the heart, anchors it to the surrounding walls, and prevents it from overfilling. The visceral pericardium is in direct contact with the heart and is also called the epicardium, and is considered as the first layer of the heart. It covers the cardiac muscle, protects it, and produces serous fluid along with the parietal pericardium. This serous fluid is called pericardial fluid which not only cushions the heart, but also decreases friction created during the beating of the heart. The middle layer is the muscular portion of the heart, and is called the myocardium. It is responsible for the contraction of the heart.