Serous membrane

In anatomy, serous membrane (or serosa) is a smooth membrane consisting of two layers of epithelial cells (as membranes), which secrete serous fluid. The inner layer covers organs in bodily cavities and is called the visceral membrane; this inner layer of epithelial cells is followed by a connective tissue; after the connective tissue is the second layer of epithelial cells of the serous membrane called the parietal layer.

The Latin anatomical name is tunica serosa. Serous membranes line and enclose several body cavities, known as serous cavities, where they secrete a lubricating fluid which reduces friction from muscle movement. Serosa is entirely different from the adventitia, a connective tissue layer which binds together structures rather than reducing friction between them. The serous membrane covering the heart and lining the mediastinum is referred to as the pericardium, the serous membrane lining the thoracic cavity and surrounding the lungs is referred to as the pleura, and that lining the abdominopelvic cavity and the viscera is referred to as the peritoneum.