A surgical instrument with separate actuatable closure and firing systems for closing a movable jaw and actuating a firing member. In one form, the surgical instrument comprises an elastic spine assembly that includes a proximal spine portion and a distal spine portion that is elastically coupled to the proximal spine portion for axial movement relative thereto between a neutral position and an elongated position such that during actuation of the firing system results in an increased application of closure motions to the movable jaw without actuating the closure system.
