Neck Injury Mechanisms And Injury Criteria

Definition And Anatomy

Sections

Neck Injury Types and Locations Neck Injury Mechanisms Neck Injury Criteria Neck Injury Tolerance Levels

The neck forms a flexible link between the head and the torso, and as such it provides the structural support for the head being both stiff yet flexible, allowing the head to rotate laterally and vertically.  It also forms part of the main spinal cord, contains blood vessels leading to the brain and face plus the main respiratory airway (trachea) and digestive intake (oesophagus). 

The neck can be divided into 2 main anatomical areas each with their own specific injuries and injury mechanisms.

Cervical Spine located at the rear of the neck consisting of the upper portion of the spine providing the mechanical support to the head plus protecting the spinal cord The soft tissue at the front of the neck containing the trachea, oesophagus and major blood vessels to the head and brain

Figure 13

The cervical spine consists of the upper 7 vertebrae, C1 – C7, which support the head, and is divided into 2 main vertebrae types.

• C1, Atlas, and C2, Axis, vertebrae
• C3 – C7 vertebrae

The Atlas and Axis vertebrae are significantly different from the rest of the vertebrae.  The Atlas has no cylindrical load bearing surface and only lateral processes, while the Axis has a much reduced frontal load bearing surface and lateral and posterior processes.  As such these bones are significantly weaker than the rest of the spine in compression, shear and bending. To maintain lateral stability between the 2 vertebrae a vertical bone projection in the Axis, the Dens, locates into to a circular opening at the front of the Atlas.  It is these bones, which allow the head to rotate, and ‘nod’.

The shear strength and bending stiffness of the neck is provided by strong ligaments joining the vertebrae together through the spinal column opening and down the vertebrae spinal processes

In comparison the rest of the cervical spinal C3 – C7 is relatively stiff and much stronger.

The definitions of motions in the cervical spine is shown below:

 
Figure 14