HORIZONTAL REINFORCEMENT FOR A MOTOR VEHICLE DOOR

The invention relates to a door () of a motor vehicle (), having an outer wall and a lining () forming a casing (), said casing () comprising: a main side reinforcement () extending longitudinally between a front edge (A) and a rear edge (C) of said casing (); an upper reinforcement () extending longitudinally along an upper edge (B) of said casing (); an exterior opening control support () of the door (), which is fixed to the upper reinforcement (); the casing () further comprising: an auxiliary side reinforcement () which extends above the main side reinforcement () longitudinally between the front edge (A) and the rear edge (C) of the casing () and is fixed to the control support for the exterior opening () of the door ().