Smallest cardiac veins contribute to normal physiologic shunting of blood. As a consequence of the input of these vessels, blood in the left heart is less oxygenated than the blood found at the pulmonary capillary beds, albeit to a very small degree. The "openings of smallest cardiac veins" are located in the endocardium. Here the smallest cardiac veins return blood into the heart chambers from the capillary bed in the muscular cardiac wall, enabling a form of collateral circulation unique to the heart. Not every endocardial opening connects to the thebesian veins as some connect to the vessels of Wearn, which are arteries.
Anterior spinal veins dural fistulas can experience venous hypertension caused by thrombosis of these veins. The anterior spinal cord, which makes up 2/3 of the entire spinal cord, gets its blood supply from the anterior spinal artery. This artery in turn receives its blood from the different radiculospinal branches, which are formed from the aorta and vertebral arteries. As the largest of the radiculospinal artery branches, the Artery of Adamkiewicz provides a large amount of blood to the anterior spinal artery, thereby also supplying a good amount to the anterior spinal cord. There is a very limited availability to research the spinal venous