The heart is located in the mediastinum and spans from the first rib to the diaphragm. It lies anterior to the vertebral column, posterior to the sternum, and between the lungs. The atria form the heart's superior tip, called the base. It is tipped towards the right shoulder and is the primary entry and exit point for the blood vessels. The lower end of the left ventricle forms the heart's inferior point, called the apex. It is angled towards the left hip and rests on the diaphragm. The heart is surrounded by a protective double-walled covering known as the pericardium, which helps anchor and firmly hold it in the mediastinum. The superficial layer of the pericardium, the fibrous pericardium, protects the heart, limits its stretching, and restricts the volume of blood inside it. The deep layer of the pericardium, the serous pericardium, comprises the outer parietal pericardium and the inner visceral pericardium or the epicardium. The pericardial cavity, which is between the parietal and visceral layers, is filled with pericardial fluid to reduce friction during heart contractions.