Looking At Degrees Of Freedom  

Coupled cars pulled by a train engine have only one degree of freedom.  This limitation on the freedom to vary is because the positions of the cars behind the engine are constrained by the shape of the track.  The human head and neck has been portrayed in three dimensional mathematical models with degrees of freedom upwards of 50 degrees.  Modeling allows engineers to simulate a wide variety of situations regarding human movement and the effects of impacts upon the cranium.

The complexity of our structure is immense and mimicking our ability to move our head and neck is difficult even with a computer.  What makes modeling so difficult is that the number of muscles that generate the required force for a movement are far greater than necessary.  It is speculated that there is more musculature available for movement than degrees of freedom in the human head and neck.  Thus, there are infinite sets of muscle forces that can satisfy angular requirements and seemingly far greater than necessary.

This means that our head and neck musculature has the ability to substitute if a muscle in a region is injured.  This is good and bad, good because if injured you have a tremendous capacity to quickly return to form, bad because injuries linger as we have the ability to substitute sets of muscle forces that can satisfy angular requirements.   Being able to perform movements efficiently if some tissue is damaged by using unaffected fibers may mislead doctors and trainers in diagnosing an injury.  Often these neck issues from trauma, once seemingly healed show up later, even years later.

It is imperative that once injured you rehabilitate the head and neck region.  Our ability to perform at high levels post injury is not always an indication that all is well.  It pays to keep strong and Get Strong.