An acoustic waveguide for an ultrasonic surgical instrument, comprising: (a) a proximal waveguide body portion defining a longitudinal axis; (b) a distal waveguide body portion having an ultrasonic blade distally projecting therefrom; and (c) an articulation body portion extending between the proximal and distal waveguide body portions, wherein the articulation body comprises a first flexible member and a second flexible member, wherein the first and second flexible members are configured to flex in a full 360-degree range of radial directions through a respective full 360-degree range of radial planes such that the articulation body portion is configured to flex in at least a first direction and a second direction to thereby deflect the ultrasonic blade relative to the longitudinal axis and through a first plane and through a second plane respectively, and wherein the second direction is different than the first direction such that the second plane is different than the first plane for multiplanar deflection of the ultrasonic blade relative to the longitudinal axis; wherein the first flexible member is a flexible member configured to receive an acoustic vibration from the proximal waveguide body portion, and communicate the acoustic vibration from the proximal waveguide body portion to the distal waveguide body portion for driving the ultrasonic blade with the acoustic vibration; and wherein the first flexible member has a set of predetermined properties and the acoustic vibration has a longitudinal vibrational component and a transverse vibrational component, and wherein the set of predetermined properties of the flexible member are configured to uncouple the longitudinal vibrational component from the transverse vibrational component; wherein the first flexible member is a first flexible wire and wherein the first flexible wire has a wire cross-sectional radius, the proximal waveguide body portion has a proximal waveguide radius, and the distal waveguide body portion has a distal waveguide radius, and wherein the wire cross-sectional radius is smaller than the proximal and distal waveguide radii, and wherein the second flexible member is a second flexible wire. (a) a proximal waveguide body portion defining a longitudinal axis; (b) a distal waveguide body portion having an ultrasonic blade distally projecting therefrom; and (c) an articulation body portion extending between the proximal and distal waveguide body portions, wherein the articulation body comprises a first flexible member and a second flexible member, wherein the first and second flexible members are configured to flex in a full 360-degree range of radial directions through a respective full 360-degree range of radial planes such that the articulation body portion is configured to flex in at least a first direction and a second direction to thereby deflect the ultrasonic blade relative to the longitudinal axis and through a first plane and through a second plane respectively, wherein the second direction is different than the first direction such that the second plane is different than the first plane for multiplanar deflection of the ultrasonic blade relative to the longitudinal axis; wherein the first flexible member is a flexible member configured to receive an acoustic vibration from the proximal waveguide body portion, and communicate the acoustic vibration from the proximal waveguide body portion to the distal waveguide body portion for driving the ultrasonic blade with the acoustic vibration; and wherein the first flexible member has a set of predetermined properties and the acoustic vibration has a longitudinal vibrational component and a transverse vibrational component, and wherein the set of predetermined properties of the flexible member are configured to uncouple the longitudinal vibrational component from the transverse vibrational component; wherein the first flexible member is a first flexible wire and wherein the first flexible wire has a wire cross-sectional radius, the proximal waveguide body portion has a proximal waveguide radius, and the distal waveguide body portion has a distal waveguide radius, and wherein the wire cross-sectional radius is smaller than the proximal and distal waveguide radii, and wherein the second flexible member is a second flexible wire.