An arm construction of an intra-oral x-ray device according to the present invention comprises at least two elongated support arms (55, 56, 55&prime；, 56&prime；) jointed to each other, into connection with a substantially first end of the first support arm (55) of which is arranged a radiation source (4) and in which at least one of the support arms (55, 56) comprises a cover which is arranged to comprise a structure openable or detachable in the longitudinal direction of the support arm, which structure is substantially of the length of the support arm or covers at least a significant portion of the length of the support arm.
