A surgical stapling instrument with a remotely articulated staple head assembly on a rotatable support shaft. A joy stick mounted to the shaft of the instrument near the handle allows for remote articulation of the staple head assembly. The staple head assembly includes a narrow contour for insertion between adjacent rib pairs without rib spreading. The staple head assembly further includes a reloadable staple cartridge which may be replaced with differently sized staples of a second cartridge. A closure trigger clamps tissue prior to stapling and cooperates with a second trigger that performs the staple firing operation. The triggers include a safety lock mechanism for preventing premature staple firing.