arm(s) of elevated plus maze apparatus open arm of elevated plus maze apparatus 2012-07-24T05:15:31Z JSmith MMO:0000266 One or both of the arms of an elevated plus maze apparatus which are not bounded or enclosed with walls. An elevated plus maze is an experimental apparatus which consists of four arms, usually two enclosed and two open, in the shape of a plus (+) upon which the test animal can walk. The maze is elevated a set distance, for example 40 to 60 cm, above the floor or platform upon which the apparatus sits. measurement_method_ontology open arm of EPM