Pericardium
CardiovascularOrgansThorax
- What it is
- A tough two-layered sac enclosing the heart and the roots of the great vessels: an outer fibrous layer fused to the diaphragm below and the great vessels above, lined by a serous layer that also covers the heart surface (epicardium).
- Function
- Anchors the heart in the mediastinum, limits sudden over-filling and lets the heart beat almost frictionlessly on a film of fluid.
- Size
- Wall ~1–2 mm thick; contains ~15–50 mL of serous fluid.
- Clinical note
- Fluid or blood accumulating in the sac can compress the heart (cardiac tamponade); inflammation (pericarditis) causes sharp chest pain eased by leaning forward.