Fainting during a violent blow to the jaw is due to a concussion and temporary impairment of brain function. In a violent blow to the jaw, the blow causes the head to be tilted back rapidly from a standstill because the neck muscles are not strong enough to counter the violence, and then decelerates the head rapidly because of the limitations of the cervical spine. In the process, the brain is subjected to accelerating and decelerating shocks and concussion occurs. Syncope occurs mainly because of transient dysfunction of the cerebellum as a result of violent impact. The vestibular cerebellum is responsible for positional awareness, and when the vestibular cerebellum is dysfunctional, limb positional awareness is impaired, and symptoms such as imbalance and vertigo occur. Therefore, when the violence is large, brain dysfunction occurs and fainting occurs; when the violence is small, the vestibular cerebellum is mainly damaged, resulting in impaired position sense, imbalance and dizziness. When fainting occurs due to the impact of violence and the severity cannot be determined, it is necessary to actively seek medical treatment.