Science today isn't the same as the science 2000 years ago was but some principles remain the same. The human knowledge constantly grows but with more knowledge there comes even more mysteries and unsolved questions, so science is always going forward.
Causes. The most common cause of a cervical herniated nucleus pulposus is gradual degeneration of the disc, attenuation (weakening) of the posterior annulus fibrosis, and subsequent protrusion of the nucleus pulposus into the spinal canal causing compression of the nerve root.
Nucleus pulposus material was implanted in the epidural space in pigs near the cauda equina. Implantation of retroperitoneal fat was used as a control. Nerve fibre degeneration, axonal swelling, increased axoplasmic density and marked attenuation and splitting of the myelin sheaths were noted in the animals exposed to nucleus pulposus material.