  We study extremal curves associated with a functional which is linear in the
curve's torsion. The functional in question is known to capture the properties
of entanglement entropy for two-dimensional conformal field theories with
chiral anomalies and has potential applications in elucidating the equilibrium
shape of elastic linear structures. We derive the equations that determine the
shape of its extremal curves in general ambient spaces in terms of geometric
quantities. We show that the solutions to these shape equations correspond to a
three-dimensional version of Mathisson's helical motions for the centers of
mass of spinning probes. Thereafter, we focus on the case of maximally
symmetric spaces, where solutions correspond to cylindrical helices and find
that the Lancret ratio of these equals the relative speed between the
Mathisson-Pirani and the Tulczyjew-Dixon observers. Finally, we construct all
possible helical motions in three-dimensional manifolds with constant negative
curvature. In particular, we discover a rich space of helices in AdS$_3$ which
we explore in detail.
