An arm retainer for supporting a patient's arm at a desired position on an articulatable support assembly secured to an operating table. The arm retainer includes a rigid arm tray (11) having a connection stud (12) protruding from the bottom side of the tray (11) for connecting the tray to the articulatable support assembly, and the tray (11) is provided with a pair of spaced openings (16) for securement of a disposable arm support liner (10) to the tray. The arm support liner (10) is comprised of a sheet of malleable material (13) with a soft engagement surface (14) for skin contact with the patient and is provided with a predetermined cut configuration for wrapping the malleable liner (10) about the patient's arm for retention of the arm therein. The line (10) has two spaced foldout tabs (17) aligned with the corresponding tray openings (16) for securing the liner to the tray (11) by folding the tabs (17) through respective of the openings (16) and thereafter against the bottom side of the tray.
