Abstract: A mud motor has integrated rotatable reamer elements. The reamer elements may be located directly radially outwardly of a rotor of the mud motor on an outer surface of the mud motor. The reamer elements may be applied to provide one or more of sizing a wellbore, smoothing a wellbore and stabilizing a bottom hole assembly and/or drill bit during drilling. The reamer elements may project from pockets formed in an outside surface of the mud motor. Axes of rotation of the reamer elements may be parallel to and/or skewed relative to a longitudinal centerline of the mud motor. Reamer devices that connect at couplings between drill string sections may be used together with the mud motor or applied separately of the mud motor. The reamer devices include inwardly-projecting elements that engage gaps between the drill string sections.