A surgical instrument (20) for cutting and coagulating tissue is provided that includes an elongate sheath (24) and an ultrasonic blade (22). In one embodiment, an ultrasonic blade (22) is positioned within a sheath (24) such that movement of the sheath (24) relative to the blade (22) results in the dissection and/or coagulation of tissue therebetween. In another embodiment, an ultrasonic blade (22) is positioned within a sheath (24) such that movement of the blade (22) relative to the sheath (24) results in the dissection and/or coagulation of tissue therebetween. The size and shape of distal ends of the blade (22) and sheath (24) determine the size and shape of the tissue being cut and/or removed from a body.
