  In this paper, we study theoretically the behaviors of the magnetic
excitations(MEs) in the normal and nematic phases of iron pnictides. The normal
state MEs exhibit commensurability to diamond and to square-like structure
transition with the increase of energy. This structure transition persists in
the spin and orbital scenarios of nematic phases, although the MEs show
anisotropic behaviors due to the C4 symmetry breaking induced by the nematic
orders. The MEs exhibit distinct energy evolution behaviors between the spin
and orbital scenarios of nematicity. For the spinnematic scenario, the
anisotropy of the MEs persists up to the high energy region. In contrast, for
the orbital-nematic scenario, it reduces dramatically in the low energy region
and is negligible in the high energy region. These distinct behaviors of the
MEs are attributed to the different origins between the spin and orbital
scenarios of nematic orders.
