Whiplash Injury – Anatomy and Mechanism

Posted by Dr Gauresh

Whiplash injury is an injury of the neck, sustained mainly during road accidents or falls from a height. The most intriguing factor in this injury is that it occurs without any physical contact of the neck with any object ! Thus, a person has almost no evidence of injury on his body, which makes it difficult to prove or disprove a whiplash injury claim.

The symptoms of a whiplash injury may not manifest at the time of the traumatic incident, but generally a few days later. Moreover, they are vague and non-specific especially in the early stages. However, a whiplash injury can cause severe disability including neck bones dislocation (neck vertebral dislocation) or upper limb paralysis. Hence, one has to be watchful for any sign of a whiplash injury, especially after a fall or an accident.

Relevant Anatomy

The spinal cord is completely enclosed in a cylindrical space between the back bones or vertebrae which is called the spinal canal. The spinal cord travels from the brain to the buttocks giving out nerves at every vertebrae. It is these nerves which travel to each part of the body and are responsible for transmission of various sensations and signals to and from the brain. The nerves exiting from the neck vertebrae carry sensations and signals to and from the neck muscles and the upper limb. This is the reason why a whiplash injury causes symptoms in neck as well as hands.

The spinal canal is slightly larger than the spinal cord and hence there is a potential space between the spinal cord and the canal. The spinal cord has 3 coverings called the piamater, arachnoid mater, and the duramater. The space between the arachnoid mater and the piamater is filled with fluid called the cerebro-spinal fluid. This fluid not only provides nutrition to the cells of the brain and spinal cord, but also perform the function of a shock absorber.

However, it is this very fluid that is responsible for the propagation of a jerky head movement to a whiplash injury of the spinal cord !

The muscular anatomy of the neck is discussed here.

Mechanism of Whiplash Injury

The response of the neck to a sudden fall or an accident is similar to the movement of a whip (used to control horses or train animals)(Picture 1). Hence, the name whiplash injury !

The sudden jerky movement of the head creates a wave like movement which puts the neck in an awkward s-shaped position. This movement violently stretches the muscles and ligaments of the neck as well as the nerve cells in the spinal cord and nerves. Nerve cells or neurons are highly sensitive and delicate structures. Thus, they are easily damaged along with the neck ligaments. Neurons lack the ability to repair themselves after injury. The overall damaged structures in the neck make it prone to inflammation in the subsequent days, which causes degradation in the functions of the neck along with neck spasm. This is why symptoms of whiplash injury mostly develop a few days after the traumatic incident !