  The periodically varying Lorentz force of the periodic solar magnetic field
generated by the solar dynamo can induce two kinds of motions: torsional
oscillations and periodic variations in the meridional circulation.
Observational evidence now exists for both these kinds of motions. We discuss
our ongoing effort in theoretically studying the variations of the meridional
circulation. Then we present our theoretical model of torsional oscillations,
which addresses the question why these oscillations start before sunspot cycles
at latitudes higher than where sunspots are seen.
