Serosa
Serosa is not to be confused with 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 called the pericardium, the serous membrane lining the thoracic cavity and surrounding the lungs is called the pleura, and that lining the abdominopelvic cavity and the viscera is called the peritoneum.