A lockable pivoting articulation joint includes a first joint section, a second joint section, a pivot bearing allowing the first and second joint sections to be rotatable in relation to each other about a main axis, and a locking mechanism on the first joint section switchable between a release condition and a locking condition. The second joint section is lockable in relation to the first joint section in at least one relative rotational position.On the second joint section a retaining surface is provided. The locking mechanism has a clamping lever attached to the first joint section to be pivotable about a clamping lever axis between a locking position and a release position. The clamping lever has a clamping surface for locking abutment on the retaining surface and the clamping surface is inclined in relation to a tangential plane.