Abstract: A surgical instrument includes a first grip branch and a second grip branch pivotably connected to the first second grip branch. The second grip branch defines an elongated shaft portion, a grip portion, and a middle piece connecting them. The instrument includes a sliding shaft element which is arranged on the shaft portion and is connectable with the first grip branch. The sliding element is detachable from the shaft portion when the grip branches are at a maximum distance from each other. The instrument has a stopper element to limit travel of the grip branches when in a locking position, and allow maximum splayed movement of the grip branches when in an unlocking position. In one embodiment at least two movement steps in two movement directions are necessary to bring the moveable stopper element from the locking position to the unlocking position.