  We have studied the motion of antihydrogen atoms in electric and magnetic
fields of arbitrary orientation. Our aim was to find an exact model of external
(centre-of-charge) and internal dynamics which would allow us to describe
antihydrogen motion in a realistic way. After analysing the kinematics of the
charge exchange reaction producing antihydrogen and of antihydrogen
deexcitation, we discuss the dynamics in cases of special fields
configurations. Finally, we propose an expression for the force acting on an
antihydrogen atom when the field configuration is arbitrary. The general
formula -- when reduced in the special field configurations -- matches the
results which we obtained independently before. The focus is both on the centre
of charge dynamics and on the accurate internal quantum characteristics.
