A formalism is presented for the nonlinear dynamics of inextensible st
iff polymers within the model of local viscous dissipation. By casting
the internal elastic forces in an intrinsic representation, enforcing
the constraint of local inextensibility through a Lagrange multiplier
function, and utilizing techniques from the differential geometry of
curve motion, the dynamics of configurations of arbitrary complexity i
s reduced to a scalar partial differential equation amenable to analyt
ical and efficient numerical study. As an example, the formalism is ap
plied to the ''folding'' dynamics of stiff polymers with pairwise self
-interactions and intrinsic curvature.