Whiplash is the common term used for a hyperflexion/hyperextension injury to the neck. This injury occurs when the neck is flexed and then extended beyond its normal range of motion. This action causes stretching and tearing of the muscles and ligaments of the neck. The pain experienced after a whiplash injury is due to tightening of the muscles that are responding to the tears they have received. By tightening up, these muscles are acting as a splint to prevent further movement and injury. These tightened muscles often lead to headaches and pain commonly experienced after a whiplash injury.