The surgical stapling apparatus includes a handle assembly, an elongated body extending distally from the handle assembly, and an articulation mechanism for articulating a tool assembly. The articulation mechanism includes a first gear rotatably mounted on a transmission shaft and configured to engage a second gear, a clutch interconnecting the second gear and a main shaft; and a yoke shaft coupled to the main shaft and adapted to linearly advance a J-channel, the J-channel operatively connected to an articulation link. A motor assembly may rotate the transmission shaft of the articulation mechanism. Alternatively, the articulation mechanism may include an articulation knob. Users may manually rotate the articulation knob to articulate the tool assembly of the surgical stapling apparatus.