An apparatus for advancement along a predetermined curved trajectory, comprising: a conduit having a conduit distal end; an elongated member having a main axis, at least partially extending within said conduit and movable therein along its length, said elongated member comprising a segmented assembly formed of a plurality of segments hingedly connected with each other, each having an orientation axis perpendicular to the main axis; and a deflecting member extending along said main axis so as to have a first state with a first extension along at least a part of the segmented assembly including its most distal segment, and a second state with a second extension along said part of the segmented assembly, the second extension exceeding the first extension.