28. The assembly of claim 27 , wherein the sleeve further includes a longitudinally projecting central extension on the sleeve first end, the longitudinally projecting central extension projecting outwardly beyond the first pair of opposed upstanding arms of the respective bone anchor.
28. The assembly of claim 27 , wherein the sleeve further includes a longitudinally projecting central extension on the sleeve first end, the longitudinally projecting central extension projecting outwardly beyond the first pair of opposed upstanding arms of the respective bone anchor. 29. The assembly of claim 28 , wherein a tube-like spacer engages the longitudinally projecting central extension.