inner lining of the fibrous pericardium is formed by
Pericardium The fibrous pericardium is the most superficial layer of the pericardium. It is made up of dense and loose connective tissue,[2] which acts to protect the heart, anchoring it to the surrounding walls, and preventing it from overfilling with blood. It is continuous with the outer adventitial layer of the neighboring great blood vessels.
Pericycle Although it is composed of non-vascular parenchyma cells, it is still considered part of the vascular cylinder because it arises from the procambium as do the vascular tissues it surrounds.