12. Motion During a Collision 0 milliseconds At the moment of impact, the car seat just begins to move and the occupant has not yet been accelerated forward.
13. Motion During a Collision 50 milliseconds As the car seatback pushes the torso forward, the spine moves forward, resulting in a straightening of the thoracic and cervical spine. Head remains stationary Seatback pushes torso forward
14. Motion During a Collision This difference in motion between the neck and torso results in an S-shaped curve, where nearly all of the bending in the cervical spine takes place in the lower cervical spine. This rapid bending in just a few joints can result in ligament damage in the lower spine. 75 milliseconds At this point in the collision, the car seat is rapidly pushing the occupant's torso forward, while the head remains stationary due to inertia. Head remains stationary Seatback pushes torso forward
16. Motion During a Collision 150 milliseconds At about 150 milliseconds, the torso has pulled so far forward on the lower neck that the head is forced backwards over the head restraint. Depending on the severity of the collision, the ligaments in the front portion of the spine can be injured during this phase of the collision. Head rotates back Seatback pushes torso forward
17. Motion During a Collision 200 milliseconds Finally, the head and torso are thrown forward by the force of the car seat. Head thrown forward Force from car seat
18. The Cervical Facet Joints Vertebral Body Facet Joints Intervertebral Disc Spinous Process Facets Normal Gliding Motion
19. Abnormal Facet Motion Pinching of facet Torso movement forward Torso moving forward Stretching of ligaments and disc Facet Joint Reflectors Stretch of facet capsule
20.
21. Nerves of the Facet Joint The pain from inflamed facet joints is transmitted by the medial branch of the dorsal ramus. Stimulation of the facet nerves often results in referred pain. Facet Joints Medial Branch Dorsal Ramus Spinous Process Spinal Cord
22. Referred Pain Patterns "... the prevalence of cervical zygapophysial joint pain was 60%." The most common facets to be injured were at C2/C3 and C5/C6. Wallis BJ, Lord SM, Bogduk N. Resolution of psychological distress of whiplash patients following treatment by radiofrequency neurotomy: a randomised, double-blind, placebo-controlled trial. Pain 1997;73:15-22. C2/3, C3 C3/4, C4/5, C4 C6/7, C6, C7 C2/3, C3/4, C3 C4/5, C5/6, C4, C5 C4/5, C5/6, C4 C7/T1, C7