Hi Laura, in very lay terms. Spinal stenosis is usually stenosis of the central canal where the spinal cord runs down between the vertebrae. The foramina are on either side of each vertebra. They are just holes/openings and the peripheral spinal nerves run through them. These nerves innervate your limbs. As we age vertebral facet joints and other spiny ligaments degenerate and can narrow these holes and touch/compress nerves.