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.
Arcuate vessels of uterus Arcuate vessels of uterus The arcuate vessels of the uterus are a component of the blood supply of the uterus. They are arteries and veins that branch from the uterine arteries and veins, respectively, with additional anastomoses from the ovarian arteries and veins, and penetrate and assume a circumferential course in the myometrium. They have also been called helicine branches of the uterus (or helicine arterioles), as they are spiral-shaped, but they should not be confused with the spiral arteries that penetrate the endometrium in the inner uterus. The radial arteries branch off from the arcuate artery through the myometrium.