Vehicle seat with articulation mechanism

The vehicle seat has a backrest which is pivotally mounted on a seating portion about a rotation axis. A retaining lever is moved relative to seating portion between a retaining position in which retaining lever maintains disabling element in active position, and a retracted position spaced apart from retaining position. The essential portions of disabling element and retaining lever are contained in radial overall dimension of case (5a) of hinge mechanism (5) defined by envelope extending along rotation axis and passing by outer edge of case.