The dorsal and ventral nerve roots arising from the spinal cord join at the intervertebral foremen to form a spinal nerve.In the thoracic segments, these mixed spinal nerves retain their autonomy and supply one intercostals segment both dermatome and myotomal.
Acute nerve root compression is usually the result of an acute disk prolapse when the contents of the nucleus pulposus of the intervertebral disk are extruded through a defect in the anulus fibrosus into the spinal canal. There they may irritate the nerve root.
Both paraplegia and quadriplegia are conditions which result from injury or trauma to the spinal cord. The spinal cord runs through the centre of the bony spine. It is like a system of telephone wires which conduct messages from the brain, through the nerves, to all parts of the body.