Vasa vasorum are networks of small blood vessels that supply the walls of large blood vessels, such as elastic arteries (e.g., the aorta) and large veins (e.g., the venae cavae).

Due to higher radial and circumferential pressures within the vessel wall layers closer to the main lumen of the artery, vasa vasorum externa cannot perfuse these regions of the vessel wall (occlusive pressure).

The structure of the vasa vasorum varies with the size, function and location of the vessels.

The converse argument is that generally artery walls are thicker and more muscular than veins as the blood passing through is of a higher pressure.

[3] The vasa vasorum are found in large veins and arteries such as the aorta and its branches.