The cannula is for insertion in an elongated opening in a pedicle extending from the posterior cortex to a predetermined depth in the pedicle. The cannula comprises an elongated first section constructed to be inserted within the opening, and an enlarged elongated second section extending outwardly from the first section and having a generally longitudinal slot extending therethrough from an inner end to an outer end thereof to enable an instrument that is straight or angled to be inserted through the outer end of the slot and through the cannula into the pedicle for a desired procedure.