It is nerve irritation caused by damage to the discs between the vertebrae. Damage to the disc occurs because of degeneration of the outer ring of the disc or because of traumatic injury. As the result, the central softer portion of the disc can herniate through the outer ring of the disc and abut the spinal cord or its nerves as they exit the bony spinal column. This rupture is what causes the commonly recognized pain of “sciatica” that shoots down the leg.
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