Abstract: An apparatus for verifying an osteotomy trajectory includes a straight rod portion extending along a first axis in a first direction, a sliding arm slidably coupled to the straight rod portion and configured to slide along a sliding direction on the straight rod portion along the first axis. The sliding arm may include a sliding portion slidably coupled to the straight rod portion to slide along the sliding direction, a pointing portion including a tip protruded along a second axis in a second direction, the second axis being at least substantially parallel to the first axis, and an extending portion having a first side attached to the sliding portion and a second side attached to the pointing portion. The apparatus further includes a fixed arm coupled to the straight rod portion and configured to mount a drill thereon to point the drill along the second axis toward the tip.