The invention concerns a clamp for a spinal affixation device which has a base body (1) crossed by a duct (2) having a longitudinal axis (3) for receiving a longitudinal support. The clamp includes a substantially planar extension (4) continuing the base body (1) and crossed by a screw hole (5) having a center axis (6) for receiving a bone screw. The duct (2) can longitudinally and rotationally lock in place a longitudinal support which is inserted therein. The longitudinal axis (3) of the duct (2) and the center axis (6) of the screw hole (5) form skewed straight lines of constant spacing (7) at a distance in the range of 4 to 10 mm.