In a typical vertebra, the vertebral foramen is the foramen (opening) of a vertebra bounded ventrally/anteriorly by the body of the vertebra, and the dorsally/posteriorly by the vertebral arch.
In the articulated spine, the successive vertebral foramina of the stacked vertebrae (together with adjacent structures) collectively form the spinal canal (vertebral canal) which lodges the spinal cord and its meninges as well as spinal nerve roots and blood vessels.