Needle guidance system

System for stereotaxic lateral extradural disc puncture has a frame fitting over the patient which provides for proper location of the cannula of the needle. The frame has a pair of right-angle members. A lower bridge frame extends horizontally and is clipped to the vertical legs of the right angle members by magnetic clips. A bridge clip fits onto the lower bridge frame and is longitudinally slidable thereon. The stem of the cannula guide slides vertically in the bridge clip. A half-channel on the top of the stem comprises the cannula guide and a bead chain fixed near the half-channel insures that the stem is vertical. Forward and rear heading guide supports are magnetically attached to the horizontal legs of the right-angle members. These supports hold magnetic strips by which a transverse disc overlay strip is held in place. A second bead chain depends from the forward end of the disc overlay strip to locate the proper alignment of the point of the cannula.