A control device (2), for a medical apparatus, having at least one sensor (5) for three dimensionally detecting an object (8) which is configured to render graspable a vector (10) for a direction by its alignment is provided, wherein the object (8) is directed to a target area, and the vector (10) generates an intersection point with a surface of the target area. The control device (2) is adapted to recognize in which target area the intersection point is located and to actuate a predefined action for the target area by the medical apparatus.