Which structure primarily anchors the heart in the mediastinum?

Which structure primarily anchors the heart in the mediastinum?

• A. The fibrous pericardium.
• B. The myocardium.
• C. The endocardium.
• D. The epicardium.

Answer: (A)

A strong, inelastic fibrous pericardial sac anchors the heart in the mediastinum. This outer layer forms the tough surrounding envelope that attaches to structures such as the diaphragm and sternum (via ligaments) and blends with the walls of the great vessels. By doing so, it holds the heart in a fixed position and helps prevent overdistension as the heart moves with breathing and body position. The heart’s own muscular layer, the myocardium, is what contracts to pump blood. The endocardium lines the interior chambers, and the epicardium is the outer surface of the heart (the visceral layer of the serous pericardium). These layers are essential for function, but they do not anchor the heart to the mediastinum the way the fibrous pericardium does.

A strong, inelastic fibrous pericardial sac anchors the heart in the mediastinum. This outer layer forms the tough surrounding envelope that attaches to structures such as the diaphragm and sternum (via ligaments) and blends with the walls of the great vessels. By doing so, it holds the heart in a fixed position and helps prevent overdistension as the heart moves with breathing and body position.

The heart’s own muscular layer, the myocardium, is what contracts to pump blood. The endocardium lines the interior chambers, and the epicardium is the outer surface of the heart (the visceral layer of the serous pericardium). These layers are essential for function, but they do not anchor the heart to the mediastinum the way the fibrous pericardium does.