An input device for a robotic medical system includes a handle configured to be rotatable about a center axis, and to be longitudinally displaceable along the center axis. The input device also includes a deflection control element disposed on the handle and configured to selectively control deflection of the distal end of a flexible medical instrument electrically coupled to the input device. Longitudinal displacement of the handle may cause or result in a corresponding longitudinal motion or deflection of the flexible medical instrument. Rotation of the handle may cause or result in a corresponding rotation of the deflection plane. Longitudinal displacement and rotation of the handle may be detected or sensed electronically.