An access system is provided for establishing an access path to a surgical site within a patient. The access system comprises an access portal defining a working channel with a central axis, and an adaptor with a mating section mountable to the access portal. The adaptor is selectively rotatable about the central axis. The access portal includes a plurality of openings and the adaptor includes a plurality of projections, each of the projections and openings being arranged so that, in a first orientation, the openings and projections align to allow mounting of the adaptor to the access portal and, in a second orientation, the openings and projections do not align to prevent disassociation between the adaptor and the access portal. The adaptor also includes a holder for a viewing device, the viewing device being movable with the adaptor about the access portal and vertically translatable relative to the access portal.
