Anatomy General 76ae8238 True about coronory sinus: A Remnant of left horn of sinus venosus B Great, middle & small cardiac vein drain into it C Thebesian valve guard its opening D All High-Yield Explanation A i.e. Remnant of left horn of sinus venosus; B i.e. Great, middle & small cardiac vein drain into it; C i.e. Thebesian valve guard its opening