Back rest of a motor vehicle seat, which has an adjustable shoulder rest

A backrest of a motor vehicle seat which comprises a backrest support onto which a shoulder rest for a separate adjustment of an upper section of the backrest is provided, said back rest support and shoulder rest having a position of smallest and largest distance from each other, whereby the shoulder rest comprises a U-shaped strap, which has two downwardly extending side arms and a basic area, said basic area laps over an upper edge of the backrest support, said side arms are linked to the backrest support at a left side swiveling point and at a right side swiveling point which are positioned at a height which is identical for both swivel points and an adjustment device which comprises at least one air bag which can be filled and emptied in a controlled manner and which is arranged between the backrest support and the shoulder rest to adjust said shoulder rest between said position of smallest distance from the backrest support and said position of largest distance from the backrest support and including re-adjusting means arranged between the shoulder rest and the backrest support which stress the shoulder rest in one of said positions.