relative to the screw shafts to allow sliding and pivoting and the screws 38 40 have semi spherical heads by selecting hole size and or head shape one or both of sliding and pivoting movement can be controlled or eliminated if desired as shown in fig4 more than two adjacent vertebrae 42 44 50 may receive adjacent assemblies 52 54 according to the present invention this in because the offset allows a single vertebra to receive two assembly parts thereby enabling the present invention assemblies to bridge adjacent vertebral spaces separated by only one vertebra this is attributable to the offset or asymmetrical characteristic of positioning a vertical portion 56 offset from a vertical centerline of the assembly to have its vertical portion 56 be nested relative to the recessed portion 58 this is a significant advantage over known designs which do not leave adequate space to attach adjacent assemblies to a sequence of adjacent vertebrae such known designs cannot be installed to bridge successive vertebral spaces separated only one vertebra implant assemblies according to the present invention are installed using procedural steps and techniques that are similar to current procedures and techniques used in implanting known cervical plates thus an advantage of the present invention is that spine surgeons are already familiar with and skilled in the procedures and techniques needed to install the present invention system the center core 16 can be made available in a variety of sizes and geometries that can be used with one or a few standard size upper and lower parts 12 14 thereby enabling the present invention to be presented as a.