A first ultrasound medical instrument includes a medical ultrasonic blade having first, second and third blade portions. The second blade portion is more bendable than either of the first and third blade portions. A second ultrasound medical instrument includes a medical ultrasonic blade having a proximal blade portion and a distal blade portion. The distal blade portion bends more easily than does the proximal blade portion. The distal blade portion includes a distal end portion adapted to contact and ultrasonically treat patient tissue. A third ultrasonic medical instrument includes a medical ultrasonic blade. The medical ultrasonic blade includes a proximal blade portion having a centerline and includes a distal blade portion in contact with the proximal blade portion at a substantially planar interface. The interface is oriented at a non-zero angle with respect to a perpendicular to the centerline at the interface.
