A surgical instrument comprising: a handle assembly; an articulatable shaft assembly (312, 490) defining an longitudinal axis (A-A) and having a proximal portion protruding from said handle assembly, said proximal portion being pivotally coupled to a distal portion that is selectively pivotable relative to said proximal portion about a first axis (FA-FA) that is substantially transverse to said longitudinal axis (A-A); a first articulation member coupled to said distal portion of said articulatable shaft assembly (312, 490); a second articulation member coupled to said distal portion of said articulatable shaft assembly (312, 490); and an articulation control member movably supported by said handle assembly and coupled to said first and second articulation members (420, 430) and configured to selectively apply pushing and pulling motions thereto such that when said articulation control member is moved to at least one first articulation control position, the articulation control member applies a first pulling motion to said first articulation member and a first pushing motion to said second articulation member to cause said distal portion to pivot about said first axis (FA-FA) in a first direction and when said articulation control member is moved to at least one second articulation control position, the articulation control member applies a second pulling motion to said second articulation member and a second pushing motion to said first articulation member to cause said distal portion to pivot about said first axis (FA-FA) in a second direction; wherein said articulatable shaft assembly (312, 490) is selectively rotatable about said longitudinal axis (A-A) relative to said handle assembly, said proximal shaft portion is attached to a rotation knob rotatably supported on said handle assembly and said articulation control member comprises an articulation ball supported within a socket in said rotation knob and selectively pivotable within said socket; characterized in that: said articulation ball is selectively axially movable within said socket; and a plurality of locking detents are formed on said articulation ball and configured to selectively engage a corresponding plurality of locking members on a portion (408, 402) of said socket to retain said articulation ball in any one of a neutral and said at least one first and second articulation control positions. a handle assembly; an articulatable shaft assembly (312, 490) defining an longitudinal axis (A-A) and having a proximal portion protruding from said handle assembly, said proximal portion being pivotally coupled to a distal portion that is selectively pivotable relative to said proximal portion about a first axis (FA-FA) that is substantially transverse to said longitudinal axis (A-A); a first articulation member coupled to said distal portion of said articulatable shaft assembly (312, 490); a second articulation member coupled to said distal portion of said articulatable shaft assembly (312, 490); and an articulation control member movably supported by said handle assembly and coupled to said first and second articulation members (420, 430) and configured to selectively apply pushing and pulling motions thereto such that when said articulation control member is moved to at least one first articulation control position, the articulation control member applies a first pulling motion to said first articulation member and a first pushing motion to said second articulation member to cause said distal portion to pivot about said first axis (FA-FA) in a first direction and when said articulation control member is moved to at least one second articulation control position, the articulation control member applies a second pulling motion to said second articulation member and a second pushing motion to said first articulation member to cause said distal portion to pivot about said first axis (FA-FA) in a second direction; wherein said articulatable shaft assembly (312, 490) is selectively rotatable about said longitudinal axis (A-A) relative to said handle assembly, said proximal shaft portion is attached to a rotation knob rotatably supported on said handle assembly and said articulation control member comprises an articulation ball supported within a socket in said rotation knob and selectively pivotable within said socket; characterized in that: said articulation ball is selectively axially movable within said socket; and a plurality of locking detents are formed on said articulation ball and configured to selectively engage a corresponding plurality of locking members on a portion (408, 402) of said socket to retain said articulation ball in any one of a neutral and said at least one first and second articulation control positions. said articulation ball is selectively axially movable within said socket; and a plurality of locking detents are formed on said articulation ball and configured to selectively engage a corresponding plurality of locking members on a portion (408, 402) of said socket to retain said articulation ball in any one of a neutral and said at least one first and second articulation control positions.