There is central spinal canal
bodies containing multiple nerves.
The Discs are jelly material in pouch between two vertebrae, with age the water content decreases(called as degenerative changes) and this material comes out of the pouch (called at protrusion) and put pressure on nerve- causing pain.
The end plates interface of vertebrae and disc, with age become rough and irregular( called as degenerative end plate changes) and act as pressure causing points around the spinal canal
the schmorls nodes are pits in the central part of end plates of vertebrae and disc material might goes inside them and when large can make vertebral bodies weak.
when there are multiple schmorl's nodes- referred as scheuermanns disease