Emissary veins passing through the foramen ovale, jugular foramen, foramen lacerum, and hypoglossal canal. Because the emissary veins are valveless, they are an important part in selective brain cooling through bidirectional flow of cooler blood from the evaporating surface of the head. In general, blood flow is from external to internal but the flow can be altered by increased intracranial pressure. A type of emissary vein goes through the sphenoidal emissary foramen inferior to the zygomatic arch with the cavernous sinus on the inside of the skull. This is an important route for spread of infection because cranial nerve VI and the
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,