The cervical (neck), the thoracic (upper back), the lumbar (lower back) and the sacrum form the spinal bones. Five spinal vertebrae from the lumbar (lower back) and connect the ribs portion with the pelvis. The spinal cord passes through the canal (spinal canal).
Stenosis means narrowing or reduction in the circumference of the canal. When the spinal canal at the lower back area (Lumbar spinal canal) strat getting narrowing due to any reason is called lumbar spinal stenosis or lumbar canal stenosis. This can causes compression to the nerves which are passing through. Narrowing of the spinal canal causes backbone pain or lower back pain.