<p>An impact element can be extended in relation to a support in the event of a motor vehicle crash. A drive mechanism causes the impact element to be extended. Components for holding and triggering the drive mechanism have an electromagnet (17) or and electric motor powered and triggered by a control device (C). An independent claim is also included for a motor vehicle with a vehicle seat having a back-rest with a head-restraint and a control device for triggering an actuator box.</p>
