A closed head injury is an injury to the brain without a breach of the skull or the brain’s surrounding tissues by a penetrating object.
The biomechanics of a closed head injury may be understood by examining the inner dynamics of the skull and brain when influenced by the forces of acceleration, deceleration and rotating motions.
When the head is subjected to rapid acceleration and then suddenly stopped, the resulting motion is not only forward and backward, but also chin down and chin up rotation as the brain pivots on the cervical spine. This rotational motion is also present when the acceleration is from the side, causing the head to move closer to the shoulders.
Two laws of physics play a role in this action. Inertia: the tendency of matter to remain at rest if at rest, and to remain in motion if already in motion. Centrifugal force: rotation bodies will move outward, away from the center of rotation.
For more information on this subject, please refer to the section on Car and Motorcycle Accidents.