What injuries are usually associated with severe head injuries which occur after a fall from a four-wheeled vehicle (microcar, quad)?

Severe head injuries, especially after a fall from a vehicle such as a quad bike, are very often accompanied by spinal injuries, particularly in the cervical spine (neck) section. This happens because the force of the impact is transmitted along the axis of the spine. For this reason, when providing first aid to a person with a head injury, you should always suspect a simultaneous spinal injury and immobilize the victim's head.