An apparatus for operating on tissue, the apparatus comprising: (a) a body assembly ; (b) a shaft assembly , wherein the shaft assembly extends distally from the body assembly, wherein the shaft assembly defines a longitudinal axis; (c) an end effector , wherein the end effector is located at a distal end of the shaft assembly, wherein the end effector comprises an ultrasonic blade; (d) an articulation section , wherein the articulation section is coupled with the shaft assembly, wherein the articulation section is operable to articulate to thereby deflect the end effector from the longitudinal axis; and (e) an articulation control assembly, wherein the articulation control assembly comprises: (i) a first threaded member having a first pitch orientation, (ii) a second threaded member having a second pitch orientation that is opposite to the first pitch orientation, (iii) a rotatable housing including an internal threading configured to engage the first threaded member and the second threaded member, and (iv) an articulation control , wherein the articulation control is configured to rotate about an axis of rotation to thereby drive articulation of the articulation section by engaging the rotatable housing member and thereby causing translation of the first and second threaded members along a path that is parallel to the longitudinal axis of the shaft assembly, characterized in that the axis of rotation of the articulation control is oriented obliquely or perpendicular to the longitudinal axis of the shaft assembly. (a) a body assembly ; (b) a shaft assembly , wherein the shaft assembly extends distally from the body assembly, wherein the shaft assembly defines a longitudinal axis; (c) an end effector , wherein the end effector is located at a distal end of the shaft assembly, wherein the end effector comprises an ultrasonic blade; (d) an articulation section , wherein the articulation section is coupled with the shaft assembly, wherein the articulation section is operable to articulate to thereby deflect the end effector from the longitudinal axis; and (e) an articulation control assembly, wherein the articulation control assembly comprises: (i) a first threaded member having a first pitch orientation, (ii) a second threaded member having a second pitch orientation that is opposite to the first pitch orientation, (iii) a rotatable housing including an internal threading configured to engage the first threaded member and the second threaded member, and (iv) an articulation control , wherein the articulation control is configured to rotate about an axis of rotation to thereby drive articulation of the articulation section by engaging the rotatable housing member and thereby causing translation of the first and second threaded members along a path that is parallel to the longitudinal axis of the shaft assembly, characterized in that the axis of rotation of the articulation control is oriented obliquely or perpendicular to the longitudinal axis of the shaft assembly. (i) a first threaded member having a first pitch orientation, (ii) a second threaded member having a second pitch orientation that is opposite to the first pitch orientation, (iii) a rotatable housing including an internal threading configured to engage the first threaded member and the second threaded member, and (iv) an articulation control , wherein the articulation control is configured to rotate about an axis of rotation to thereby drive articulation of the articulation section by engaging the rotatable housing member and thereby causing translation of the first and second threaded members along a path that is parallel to the longitudinal axis of the shaft assembly, characterized in that the axis of rotation of the articulation control is oriented obliquely or perpendicular to the longitudinal axis of the shaft assembly. <EOS>