An apparatus, comprising: (a) a body ; (b) a shaft assembly extending distally from the body, wherein the shaft assembly defines a longitudinal axis, and wherein the shaft assembly comprises: (i) a rigid shaft member , and (ii) a flexible shaft member ; (c) a deflection actuation assembly comprising: (i) a deflection control knob , (ii) a first translatable actuation member at least partially disposed within the deflection control knob, and (iii) a second translatable actuation member extending through the shaft assembly, wherein the second translatable actuation member couples the first translatable actuation member with the flexible shaft member of the shaft assembly, wherein the deflection control knob is rotatable about the longitudinal axis to thereby drive the first and second translatable actuation members longitudinally, wherein the flexible shaft member is configured to deflect away from the longitudinal axis in response to translation of the first and second translatable actuation members longitudinally; and (d) a dilation catheter , wherein the dilation catheter is slidable relative to the shaft assembly, wherein the dilation catheter comprises an expandable dilator ; and wherein the deflection actuation assembly further comprises a tab fixedly secured to the deflection control knob, wherein the first translatable actuation member comprises a cam slot , wherein the tab is disposed in the cam slot, wherein the second translatable actuation member comprises a push-pull wire, and wherein the first translatable actuation member comprises a cam barrel, wherein a proximal end of the push-pull wire is secured to the cam barrel, wherein a distal end of the push-pull wire is secured to a distal end of the flexible shaft member. (a) a body ; (b) a shaft assembly extending distally from the body, wherein the shaft assembly defines a longitudinal axis, and wherein the shaft assembly comprises: (i) a rigid shaft member , and (ii) a flexible shaft member ; (i) a rigid shaft member , and (ii) a flexible shaft member ; (c) a deflection actuation assembly comprising: (i) a deflection control knob , (ii) a first translatable actuation member at least partially disposed within the deflection control knob, and (iii) a second translatable actuation member extending through the shaft assembly, wherein the second translatable actuation member couples the first translatable actuation member with the flexible shaft member of the shaft assembly, wherein the deflection control knob is rotatable about the longitudinal axis to thereby drive the first and second translatable actuation members longitudinally, wherein the flexible shaft member is configured to deflect away from the longitudinal axis in response to translation of the first and second translatable actuation members longitudinally; and (i) a deflection control knob , (ii) a first translatable actuation member at least partially disposed within the deflection control knob, and (iii) a second translatable actuation member extending through the shaft assembly, wherein the second translatable actuation member couples the first translatable actuation member with the flexible shaft member of the shaft assembly, wherein the deflection control knob is rotatable about the longitudinal axis to thereby drive the first and second translatable actuation members longitudinally, wherein the flexible shaft member is configured to deflect away from the longitudinal axis in response to translation of the first and second translatable actuation members longitudinally; and (d) a dilation catheter , wherein the dilation catheter is slidable relative to the shaft assembly, wherein the dilation catheter comprises an expandable dilator ; and <EOS>