  There are two competing descriptions of nematic liquid crystal dynamics: the
Ericksen-Leslie director theory and the Eringen micropolar approach. Up to this
day, these two descriptions have remained distinct in spite of several attempts
to show that the micropolar theory comprises the director theory. In this paper
we show that this is the case by using symmetry reduction techniques and
introducing a new system that is equivalent to the Ericksen-Leslie equations
and includes disclination dynamics. The resulting equations of motion are
verified to be completely equivalent, although one of the two different
reductions offers the possibility of accounting for orientational defects.
After applying these two approaches to the ordered micropolar theory of
Lhuiller and Rey, all the results are eventually extended to flowing complex
fluids, such as nematic liquid crystals.
