The locking component of a swivel joint, such as one formed on the outer circumference of the bearing component, is engaged with at least one groove-like recess on the outer circumference of the bearing component in a specific adjustment position. Relative to this recess, especially the recess on the outer circumference of the swivel joint bearing component, the locking component assumes a pre-set position or alignment, particularly the end position when the cushion is in a horizontal or vertical orientation.It is also the end position of the rotatable bearing component of the swivel joint. The locking part located on the outer circumference of the bearing component of the swivel joint takes the form of, for example, a deformable thickened portion of the material or, for example, a rib.