An articulating mechanism for remote manipulation of a surgical or diagnostic tool comprises an elongate shaft having a longitudinal axis and a plurality of axially aligned links located at the distal end of the shaft. The articulating mechanism also includes an actuating element connected to and configured to cause movement of the axially aligned links and a locking mechanism located proximal of the axially aligned links. The locking mechanism including a collar mechanism through which the actuating element extends and a locking member movable between first and second positions. The collar mechanism frictionally impedes motion of the actuating element when the locking member is in the first position and the collar mechanism allows translation of the actuating element when the locking member is in the second position.
