<prompt> What is true about sinus venosus?Forms rough wall of right atriumForms smooth wall of right atriumForms right coronary sinusForms left leaflet of coronary sinus  <response>: Sinus venosus forms smooth posterior pa or sinus venarum of right atrium. BD CHAURASIAS HUMAN ANATOMY VOLUME1. 6TH EDITION.Page no 255 