The spinal cord branches out to all parts of the body. The part of a nerve that connects to the spinal cord is called a nerve root. If one of these roots is injured or pinched, pain, weakness, numbness or tingling may be felt in the part of the body served by that nerve.
When a spinal disc ruptures, it may press on a nerve root.
The bones creating the spinal canal may grow inward, pinching a nerve root.
If a spinal disc weakens, vertebral bones above and below may touch, pinching nearby nerve roots. Bony spurs also may press on the nerves.
The nerve roots leaving the lower back serve the legs. When a lumbar root is injured, pain, weakness, numbness or tingling may be felt in the buttocks, leg or foot. This pain is usually called sciatica.