The vertebral arteries are two blood vessels which originate from the subclavian arteries on each side of the body. They carry oxygenated blood and supply regions of the brain. From its point of origin, the vertebral arteries run up in the transverse foramina, one on each side of the upper part of the vertebral column, through small holes in the lateral aspect of the cervical vertebrae. At the base of the head, they fuse together a bigger-caliber blood vessel, which is the basilar artery. The left vertebral artery is usually larger and carries more blood than the right.