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.
The nucleus presses against the annulus, causing the disc to bulge or prolapse outward. The bulged disc material is still contained within the annulus. But in some cases, the nucleus pushes completely through the annulus and squeezes out of the disc. This is called a disc herniation or protrusion. Herniation and protrusion are two words for the same thing. If a piece of the disc breaks off, it's called a sequestered fragment. Surgery is almost always needed for sequestration. The loose piece can enter the spinal canal and put pressure on the spinal cord or spinal nerve roots causing serious problems.