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.
Roman Leaders: The 10 Greatest Generals behind the Empire. From the formation of the Roman Republic in 509 BCE, through the Roman Empireâs zenith around 117 CE, and even up until the Fall of Rome and the Empireâs adoption of Constantinople as its capital in 330 CE, war played a key role in Roman expansion across the northern hemisphere.