MOSFET source to inductive load

In H-Bridge MOSFET design, two sets of MOSFETS are usually attached to the motor. The upper MOSFETS have their sources set to the inductive load (motor). How is it possible that these FET's are turned on when the inductive load drops all the voltage when un-charged? How does voltage-GATE-SOURCE operate in this condition?

Thanks for any help!

Motors have low inductance. It starts up similar to a transformer with shorted secondary. It does have some inductance but this will only hinder turn on time of MOSFET slightly.

I think it is more common to use P and N Fets; that way all the FETs are running common-source, and gate boost for the upper FETs is not needed.