A surgical tool assembly. A surgical end effector is movably coupled to a shaft assembly by an articulation joint that is configured to facilitate selective articulation of the surgical end effector relative to the shaft assembly. The shaft assembly includes a proximal end portion and a distal end portion. The distal end portion is operably coupled to the articulation joint. An elongate notch is provided in the distal end portion and is located on one lateral side of a shaft axis that is defined by the shaft assembly. The shaft assembly may be configured to prevent the distal end portion from buckling when an axial actuation motion is applied to the proximal end.
