Vein limbs. The Thebesian veins within the myocardium of the heart are valveless veins that drain directly into the chambers of the heart. The coronary veins all empty into the coronary sinus which empties into the right atrium. The dural venous sinuses within the dura mater surrounding the brain receive blood from the brain and also are a point of entry of cerebrospinal fluid from arachnoid villi absorption. Blood eventually enters the internal jugular vein. "Phlebology" is the medical specialty devoted to the diagnosis and treatment of venous disorders. A medical specialist in phlebology is termed a phlebologist. A related image
Smallest cardiac veins They drain the myocardium and run a perpendicular course to the endocardial surface, directly connecting the heart chambers to the medium-sized, and larger coronary veins. Thebesian veins have been successfully identified by following the route of contrast flow - during catheterization procedures - from the subendocardium, through the thebesian veins, into larger veins, and into the coronary sinus. The coronary sinus empties into the right atrium. The thebesian venous network is considered an alternative venous drainage of the myocardium. Thebesian veins draining into the left heart, along with deoxygenated blood originating from the bronchial veins draining into the pulmonary veins,