Thispaperestablishesanon-linearfiniteelementmodel(NFEM)ofL4-L5lumbarspinalsegmentwithaccuratethree-dimensionalsolidligamentsandintervertebraldisc.Forthepurpose,theintervertebraldiscandsurroundingligamentsaremodeledwithfour-nodalthree-dimensionaltetrahedralelementswithhyper-elasticmaterialproperties.Puremomentof10N·mwithoutpreloadisappliedtotheuppervertebralbodyundertheloadingconditionsoflateralbending,backwardextension,torsion,andforwardfle...