A modular ceiling-mounted medical services system including a vertical column supported by an articulating arm assembly. Rotational joints connect the column to the lower arm, the lower arm to the upper arm, and the upper arm to the ceiling mount. Rotational movement at each of the joints is controlled by an electrically-released electromagnetic brake, and all of the brakes may be controlled by a switch panel on the column. Thus, the entire assembly is held in place until the switch is activated. Slight hand pressure is sufficient to operate the switch while simultaneously pushing or pulling the column into the desired position. The service lines that supply the outlets in the column all pass through large central openings in the brakes.