Improved support structures and systems are disclosed for installing tablet devices, display screens, flat screen monitors, or medical devices within a wide variety of environments. A core arm extends from a rear end, toward a front end, in which the rear end is configured to be pivotably mounted either directly to a mount structure, or to an extension arm that in turn is mounted to a mount structure. The front end is configured to be pivotably mounted to a front-end panel mount structure. The structures and systems can be configured for light or heavy configurations, with or without the use of an extension arm, and can provide fully concealed cable routing, in which one or more cables are readily accessible, via snap fit covers, for easy installation and maintenance, which can provide a clean structure that can readily be serviced and cleaned as desired.