There are four phases that occur during a whiplash injury and all four take place in less than one half of a second. The injury itself is determined by the different forces that act upon the body at this time. The movements that the body undergoes are both sudden and forceful and can cause damage to the vertebrae, nerves, discs, muscles and ligaments of both the neck and spine.



The first phase takes place as the car continues on its trajectory, whilst the body strains against the seatbelt. This results in the middle area of the back to be forced against the backrest of the car seat and causes an upward force in the passenger that compresses the discs and joints of the cervical spine. Because the car itself is still moving, it pushes the torso forward and moves the head backwards at the same time that creates a shearing force in the neck. The majority of the damage caused in this phase is caused before the head makes contact with the headrest.

The second phase takes place as the body reaches its maximum acceleration which can be as much as 2 times the speed of the vehicle itself. At this point, however, the head continues on its backwards journey. Combined with the elasticity of the seat's back, an "s" shaped curve forms in the spine which increases the acceleration of the torso; the body is still moving forward while the head is still moving back and another shearing force is created in the neck. It is during this phase that most of the injuries to bones, joints, nerves and discs take place.

The body begins its journey back and into the seat during the third phase, whilst the head and neck move forward at peak acceleration. If the brakes have been applied during this phase, the resulting deceleration increases the exaggerated movement of the neck and the shearing forces that are involved. This causes the body to move forward again and, at this point, any slack in the car's seatbelts will be taken up.

The fourth phase of the whiplash motion is usually the most damaging. Because the seatbelt is now restraining the torso, the head moves forward without obstruction, causing a violent bend in the neck. This strains muscles and ligaments, tears fibres in the spinal discs and the vertebrae are forced out of their natural positions. The spine itself becomes elongated and the motion of the head can cause the brain to impact upon the inside of the skull.

The resulting symptoms of the four phases of the whiplash injury can include neck pain, back pain, dizziness, headaches, blurred vision, fatigue and mood-swings. This can be inconvenient at best and at worst severely debilitating, if not treated correctly.

A whiplash injury and the associated disorders that may manifest as a result can cause loss of earnings as well as impact upon a sufferer's social well-being. Personal injury law firms now regard whiplash compensation claims as a specialist area of personal injury law.