Nerve Pressure or Damage - Pressure on nerve roots in the spinal canal can be caused in a variety of ways; from injury or overuse as mentioned above or from disease or degeneration as follows:
Herniated, bulging, or compressed discs - Spinal discs are round, flat discs of tissue that cushion the bones (vertebrae) of the spine. If discs get damaged from injury, disease or even the normal process of aging, they can be compressed, bulged or even rupture. This can interfere with nerve function and create pain, numbness or weakness in the back or extremities.
Spinal misalignments called subluxations can also pinch nerves creating pain, or cause nerve interference that can actually affect other bodily functions.