US Patent 7641659 Spinal access instrument

A method of, and surgical instrument for accessing first and second pedicle locations of a spinal column area. The surgical instrument including a blade member slidably positionable along first and second wires. The instrument having a nested arrangement of members, including a portal member having an elongated aperture to access the first and second pedicle locations. The nested arrangement further including a plurality of members configured and sized to incrementally expand the access opening to the spinal column area.