what causes a friction rub?
<answer> Friction rub is an auscultatory sound caused by the rubbing together of two serous surfaces, as in pericardial rub. <context> 1. to move something over a surface with friction. 2. the action of such movement. 3. friction rub. friction rub an auscultatory sound caused by the rubbing together of two serous surfaces, as in pericardial rub; called also rub. pericardial rub (pericardial friction rub) a scraping or grating noise heard with the heart beat, usually a to-and-fro sound, associated with an inflamed pericardium. Patients often complain of pleuritic discomfort that radiates in the chest, especially during inhalation. This condition must be distinguished from angina pectoris. pleural rub (pleuritic rub) a friction rub caused by friction between the visceral and costal pleurae. per·i·car·di·al fric·tion sound