A medical instrument assembly comprises an elongated shaft, a tool carried by the distal end of the elongated shaft for performing a medical procedure on a patient, a plurality of controllably bendable sections spaced along the elongated shaft and disposed proximal to the tool, a plurality of actuation elements extending within the elongated shaft for respectively actuating the controllably bendable sections, and an instrument coupler mounted to the proximal end of the elongated shaft, with the instrument coupler configured for coupling an electromechanical drive to the actuation elements. A robotic medical system comprises the previously described medical instrument assembly, a user interface configured for generating at least one command, a drive unit coupled to the plurality of actuating elements of the medical instrument assembly, and an electric controller configured, in response to the command(s), for directing the drive unit to moves the actuating elements to actuate the controllably bendable sections.