A one-piece expandable flat bearing structure formed by at least partially elastically deformable struts which are separated from each other by openings in the bearing structure. The bearing structure can assume at least one compressed condition and at least one expanded condition and has at least one expansion direction. The bearing structure has anchor regions, from which spring struts, which are elastically resilient with respect to the anchor regions, extend to a resiliently deflectable end of the spring struts, a hinge strut adjoining said end. The spring struts and the hinge struts are of such a configuration and arrangement that both the compressed condition of the bearing structure and also the expanded condition of the bearing structure is stabilized by a spring action emanating from the spring struts.