Spinal DiseasesSpinal NeoplasmsIntervertebral Disc DegenerationSpondylitis, AnkylosingSpinal CordLumbar VertebraeSpinal Cord InjuriesNerve FibersMuscle Fibers, SkeletalDietary FiberInjections, SpinalSpinal NervesSpinal Cord DiseasesAnesthesia, SpinalSpinal Nerve RootsSpinal Cord NeoplasmsSpinal CanalSpinal Cord CompressionMineral FibersSpinal StenosisMuscle Fibers, Fast-TwitchSpinal FusionMuscle Fibers, Slow-TwitchCotton Fiber