A steering mechanism is used as part of a medical device such as a catheter or an endoscope to allow movement of a steerable distal portion of the catheter or endoscope. The mechanism can include a elongate housing and an actuation system. The elongate housing is adapted to be coupled to the steerable portion of the medical device. The actuation system includes an actuator, a first cam, and a second cam. The actuator can move the first cam between a first position and a second position as the actuator is moved along a first axis (or about a second axis different than the first axis). Movement of the first cam between its first and second positions moves the steerable portion of the medical device along a first plane. The actuator can move the second cam between a first position and a second position as the actuator is moved along the second axis (or about the first axis). Movement of the second cam between its first and second positions moves the steerable portion of the medical device along a second plane different than the first plane.