  We discuss how the quark masses and their mass splitting affect the baryons
in the Skyrme model as well as the Witten-Sakai-Sugimoto (WSS) model. In both
cases baryons are described by solitonic objects, i.e. Skyrmions and
instantons, respectively. After the quantization of their zeromodes the
nucleons become quantum states of a rotor. We show how the quark mass affects
the moment of inertia and we provide a semi-analytic approach valid in the
small-mass limit. Additionally, we show how the two lightest quarks' mass
splitting affects the moments of inertia of the Skyrmion and induces an isospin
breaking effect. This effect turns out not to be enough to split the degeneracy
in the neutron-proton multiplet, but it splits some of the states in the Delta
multiplet. Unlike the basic Skyrme model, the WSS model already includes vector
mesons and another mechanism to transfer isospin breaking from quark masses to
the solitons is known. We compute the splitting of the moment of inertia in the
small-mass limit in the WSS model and combine the two effects on the spectrum
of baryons, in particular the Deltas.
