A surgical method and apparatus for accurately aligning the trajectory of, guiding of, and introducing or withdrawal of an instrument is disclosed. The apparatus includes a base which has a movable member movably attached to the base. The movable member has a passage therein which forms a portion of...http://www.google.co.uk/patents/US6752812?utm_source=gb-gplus-sharePatent US6752812 - Remote actuation of trajectory guide
