An ultrasonic surgical instrument, comprising: (a) an end effector including an ultrasonic blade; (b) a body assembly; and (c) a shaft assembly (14, 214) having a first articulation section, wherein the articulation section comprises proximal, distal, and intermediate links (68, 70, 72); the shaft assembly longitudinally extending from the body assembly to the end effector and including an acoustic waveguide, comprising (i) a proximal waveguide body portion positioned proximally from the first articulation section and defining a longitudinal axis, (ii) a distal waveguide body portion positioned distally from the first articulation section and in acoustic communication with the ultrasonic blade distally projecting therefrom, and (iii) an articulation body portion extending through the first articulation section between the proximal and distal waveguide body portions, wherein the articulation body portion is configured to flex a first direction to thereby deflect the ultrasonic blade relative to the longitudinal axis and through a first plane, and wherein the articulation body portion is further configured to flex a second direction to thereby deflect the ultrasonic blade relative to the longitudinal axis and through a second plane, 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 articulation body portion includes a first flexible member, and wherein the first articulation section of the shaft assembly is configured to limit the first flexible member to a predetermined minimum bend radius, R, via cooperating distal and proximal stops (268, 270) on each link, wherein the proximal stop on one link (68, 70, 72) is configured to engage the distal stop on another adjacent link (68, 70, 72) to thereby limit collective articulation of articulation section. (a) an end effector including an ultrasonic blade; (b) a body assembly; and (c) a shaft assembly (14, 214) having a first articulation section, wherein the articulation section comprises proximal, distal, and intermediate links (68, 70, 72); the shaft assembly longitudinally extending from the body assembly to the end effector and including an acoustic waveguide, comprising (i) a proximal waveguide body portion positioned proximally from the first articulation section and defining a longitudinal axis, (ii) a distal waveguide body portion positioned distally from the first articulation section and in acoustic communication with the ultrasonic blade distally projecting therefrom, and (iii) an articulation body portion extending through the first articulation section between the proximal and distal waveguide body portions, wherein the articulation body portion is configured to flex a first direction to thereby deflect the ultrasonic blade relative to the longitudinal axis and through a first plane, and wherein the articulation body portion is further configured to flex a second direction to thereby deflect the ultrasonic blade relative to the longitudinal axis and through a second plane, 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, (i) a proximal waveguide body portion positioned proximally from the first articulation section and defining a longitudinal axis, (ii) a distal waveguide body portion positioned distally from the first articulation section and in acoustic communication with the ultrasonic blade distally projecting therefrom, and (iii) an articulation body portion extending through the first articulation section between the proximal and distal waveguide body portions, wherein the articulation body portion is configured to flex a first direction to thereby deflect the ultrasonic blade relative to the longitudinal axis and through a first plane, and wherein the articulation body portion is further configured to flex a second direction to thereby deflect the ultrasonic blade relative to the longitudinal axis and through a second plane, 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 articulation body portion is configured to flex a first direction to thereby deflect the ultrasonic blade relative to the longitudinal axis and through a first plane, and wherein the articulation body portion is further configured to flex a second direction to thereby deflect the ultrasonic blade relative to the longitudinal axis and through a second plane, 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,