The lumbar spinal canal is the space inside the lower spine that carries nerves to your legs. It is very narrow. Over the course of many years, the bone and tissue around the canal grow, causing the canal to become even more narrow over time. This narrowing is called "stenosis." As the lumbar spinal canal narrows, the nerves that go through it are squeezed. This squeezing may cause back pain, leg pain and weakness.
When people say they have a "slipped" or "ruptured" disk in their neck or lower back, what they are actually describing is a herniated disk-a common source of pain in the neck, lower back, arms, or legs.