What is Pericardium, definition and function. Pericardium is a tough, two-layer membranous sac that encloses the HEART. The pericardiumâs fibrous outer layer, called the fibrous pericardium, protects the heart from contact with the chest wall and other structures in the chest, including the LUNGS and the sternum.he inner layer of the pericardium is a filmy envelope. Its two surfaces are the parietal pericardium, which contacts the fibrous pericardium, and the epicardium, which covers the MYOCARDIUM somewhat like a wet tissue. Inside the envelope is a watery fluid that lubricates the heart.
Roman Empire Timeline. Timeline Description: The Roman Empire was one of the greatest civilizations in history. It began in Rome in 753 BC. Rome controlled over two million square miles stretching from the Rhine River to Egypt and from Britain to Asia Minor. This timeline highlights the major events in the history of Ancient Rome.
The Roman Empire began to slowly decline in the 3rd century AD, one of the main causes of Rome's early decline was a series of plagues, most notably the Plague of Cyprian, which decimated the population of the Empire, making it harder for Roman Emperors to levy armies and raise taxes.