Spinal stenosis is a narrowing of the open spaces in the spinal column. The spaces are passageways for the spinal cord and nerves. The narrowing can cause the nerves to become compressed or pinched. The spinal nerves can become compressed against the vertebral bone, which can interfere with nerve function, causing pain in the spine or another part of the body. A spine with stenosis has one or more of the open spaces narrowed. Spinal stenosis most commonly affects the cervical (upper) and lumbar (lower) regions of the spine.