We've learned that the heart wall's soft inner most layer is the endocardium, the second layer of muscle is the myocardium and the third protective layer is the epicardium
There is a protective bag outside the heart that is called the pericardium.
The pericardium has liquids in it, and it keeps the heart from getting shaken with every movement the body makes.
![pericardium](https://upload.wikimedia.org/wikipedia/commons/thumb/7/78/Blausen_0724_PericardialSac.png/480px-Blausen_0724_PericardialSac.png)
(from: wikipedia - pericardium)
Kid Facts - Blast from the past: Brachial Artery