The space between each vertebrae through which the nerves from the spine can branch-off and supply various parts of the body is called a neural foramen.
There are 33 vertebrae and between every two vertebrae arise two neural foramen.
They are present on either side of the gap.
In any such condition when there is no foramen or there is a narrowing of the foramen.
It becomes difficult to pass the nerve impulses from the brain to the parts of the body.