An apparatus comprises a shaft, and end effector, and an articulation section. The articulation section is disposed between the shaft and the end effector. The articulation section includes a proximal portion and a distal portion. The distal portion is pivotable relative to the proximal portion about a first pivot axis. A reinforcement member extends between the proximal and distal portions. The reinforcement member is configured to pivot relative to the proximal portion about a second pivot axis. The reinforcement member is configured to pivot relative to the distal portion about a third pivot axis. An articulation section may include a combination of a pivoting section and a flexing section. Reinforcement members may prevent a firing beam from buckling as the firing beam is driven through an articulated articulation section.
