sentences:  Not every endocardial opening connects to the thebesian veins as some connect to the vessels of Wearn, which are arteries.Therefore, the endocardial opening must be traced to a vein before it is definitely called an opening of the smallest cardiac veins.The thebesian veins are named after the German anatomist Adam Christian Thebesius, who described them in a 1708 treatise called "Disputatio medica inauguralis de circulo sanguinis in corde".