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===Pericardium===

===Pericardium===

The pericardium is the membrane that surrounds and protects the heart. It is composed of two layers separated by a narrow cavity. The inner layer is firmly attached to the heart wall and is known as the visceral layer or epicardium. The outer layer is composed of relatively inelastic connective tissue and is termed the parietal layer. This fibrous layer prevents distension of the heart, thus preventing excessive stretching of the heart muscle fibres. The cavity between the two layers contains a small volume of fluid which serves as a lubricant, facilitating the movement of the heart by minimising friction. The sternopericardiac ligament connects the parietal layer to the sternum and the phrenopericardiac ligament joins the parietal layer to the diaphragm. The latter is present only in the canine.

The pericardium is the membrane that surrounds and protects the heart. It is composed of two layers separated by a narrow cavity. The inner layer is firmly attached to the heart wall and is known as the visceral layer or epicardium. The outer layer is composed of relatively inelastic connective tissue and is termed the parietal layer. This fibrous layer prevents distension of the heart, thus preventing excessive stretching of the heart muscle fibres. The cavity between the two layers contains a small volume of fluid which serves as a lubricant, facilitating the movement of the heart by minimising friction. The sternopericardiac ligament connects the parietal layer to the sternum and the phrenopericardiac ligament joins the parietal layer to the diaphragm. The latter is present only in canine and swine.

===Layers of the Heart Wall===

===Layers of the Heart Wall===