Austin Peay State University indicates the pericardium envelopes the heart to protect the organ from infection, to prevent overfilling of the heart and to lubricate the heart while it moves in the chest cavity. The pericardium anchors the heart and its major blood vessels to the chest wall. Cleveland Clinic explains the pericardium helps the heart pump blood more efficiently by keeping it from over-filling as the muscle expands.
Folia Medica Cracoviensia states the perdicardium helps the heart keep an adequate position for the pumping blood, maintains low transmural pressure between the outer walls of the heart and the chest and aids in filling the chambers of the heart. The pericardium keeps other structures of the chest from touching the heart.
MedicineNet.com explains the outer portion of the pericardium features a tough, thick wall of tissue that attaches to the diaphragm and sternum. The inner portion loosely attaches to the outer heart wall.
The National Heart, Lung and Blood Institute states the pericardium is a two-layered sac that has fluid in between the layers to prevent friction. Inflamed and thickened parts of the pericardium rub against each other and cause chest pain with a condition known as pericarditis. The most common cause of pericarditis is a viral infection, and symptoms include chest pain that gets worse when a patient inhales and improves when they sit upright or lean forward.