The medallion at the centre of this back is carved as a separate panel and set into the frame, and the reason is grain direction.
The back rail of a sofa runs horizontally, so its grain runs side to side. The medallion, with its urn and upright foliage, reads vertically. Carve it directly into the horizontal rail and every vertical element in the design would be cut across the grain - which means short fibres at every stem and leaf edge, and a surface that will never take a clean cut or hold a crisp arris.
So our artisans carve the medallion in its own piece of timber with the grain running vertically, to suit the design, and let it into a recess cut in the rail. The joint is then covered by the carved scrolling that frames the oval.
It is more work than carving straight into the rail, and it is the difference between foliage that stays sharp for a lifetime and foliage that softens within a few years of being dusted.