Abstract: An anterior cervical plate system is provided. The cervical plate includes a retention ring with a deflectable flange that is upwardly spaced from the top surface of the ring and configured to prevent an inserted bone fastener from backing out of the plate. The plate includes a locking pin having a camming surface and a blocking surface. When the camming surface is moved into position adjacent to the flange, the flange is free to flex out of the way of a bone screw being inserted into or removed from the plate. When the blocking surface is positioned adjacent to the flange, outward deflection of the flange is prevented to retain the bone screw inside the plate. The locking pin is rotated through a camming surface to bring a blocking surface against the flange deflecting the flange onto the head of the bone screw.