The spine is made up of ring-shaped bones called vertebrae that are strung together like beads along the spinal cord, a bundle of nerves that connect with the brain and control much of our movement. Stenosis occurs when the interior of the vertebrae -- the spinal canal -- is too narrow, squeezing the spinal cord and nerve roots.
Although some people are born with this condition, it is more likely to occur in people over the age of 50 as a result of the aging spinal bones, which can produce bone spurs or enlarged joints that protrude into the spinal canal.