A retractor for use in spinal surgery comprises a frame including a ring member defining a generally central interior space. A plurality of blades is releasably supported respectively to slidable arms each supported on the ring member for individual translational movement relative to the ring member. The blades define an initial substantially enclosed opening that is expandable for use in a surgical procedure. A clutch mechanism supported on the ring member is associated with each arm to individually selectively engage each such arm with a rotatable main gear such that upon rotation of the main gear by a single actuator any one, all or any desired combination of arms may be translated relative to the ring member to move the blades and expand the opening in one or more selected desired directions.
