Fibrous pericardium

The fibrous pericardium is the outermost layer of the pericardium, forming a tough, dense, fibro-collagenous sac that surrounds the heart and the roots of the great vessels. It is composed primarily of collagen fibers with some elastic fibrils, providing structural support and limiting acute cardiac distention.

The fibrous pericardium is continuous superiorly with the adventitia of the great vessels, attached inferiorly to the central tendon of the diaphragm, and anteriorly to the posterior surface of the sternum by the sternopericardial ligaments.

Its main function is to maintain the position of the heart within the thorax and serve as a protective barrier against infection and malignancy from adjacent structures