We can divide the pericardium into two layers. We have the outer layer and the inner layer. The outer layer is shown in purple in the following diagram. And the outer layer consists of strong fibrous proteins that give our pericardium its strength. So the outer layer is responsible for not only attaching the heart to different parts of the body, but it also protects the heart from physical damage. Now the inner portion of the pericardium is also known as the inner cirrus layer and cirrus comes from the word serum because this section actually contains of a fluid that resembles serum.