Asymmetric dynamics of the inner core and impact on the outer core

The history and present state of knowledge of the dynamics of the inner core are outlined in this paper. The observations that motivated ideas on the dynamical processes are introduced, but the main objective is really to concentrate on the diverse dynamical models that have been and are currently proposed for the formation and evolution of the inner core. A deliberate choice has been made of reproducing key figures from the literature in a didactic attempt to provide clear and quick identification for these models. This review looses impartiality concerning recent models, notably those aiming at explaining the hemispherical asymmetry. A preference for an intrinsic dynamic mode of the inner core is expressed, as opposed to the distant influence of the dynamics of the mantle through heat-flux heterogeneities. Meanwhile, the opinion is conveyed that the dynamics of the inner core is largely not understood yet and that every model must be considered with a critical eye.