256 / 462
GAZETTE
of the impact snapping the head
backward, happens so quickly that the
anterior neck muscles do not have a
chance to relax. As a result they act as
an anchor on the mandible holding it
still and forcing the mouth open
excessively, as the head continues to
move backwards.
This action, the whipping excessively
open of the mouth and its subsequent
closure into normal position, results in
a self-reducing dislocation of the TMJ.
The masticatory and cervical
musculature, ligaments and the
synovial tissues of the temporo-
mandibular joint are simultaneously
injured. A frequent result of this
type of injury is the anterior
displacement of the TMJ disc and
posteriorization of the mandible as
seen in figure 2.
Normal Disc Relationship
Anterior Disc Displacement
Posteriorization of Mandible
Figure 2
The anterior displacement of the TMJ
disc has been demonstrated to be the
primary aetiology of progressive
disease which results in degenerative
arthritis. When the ligaments holding
the disc in place become stretched or
torn due to the displacement, this can
result in permanent damage.
This injury is particularly important
because it is well documented that 60%
of the people involved in motor
accidents do not fully recover.
Figure 3.
The clicking sound that occurs during
the opening movement of the mandible,
is actually the repositioning of the
mandibular condyle under the TMJ disc
and the restoration of the normal
functional relationship.
In a whiplash injury, particularly a rear
end collision, the whipping of the head
backward results in spasm of the
anterior cervical musculature. One of
the most common pathological changes
in the musculoskeletal system is the
creation of the dysfunctional
relationship between the cranium,
mandible and cervical vertebrae
demonstrated by the loss of the neck's
lordotic curve. This loss results in the
straightening of the cervical vertebrae
which pulls the cranium forward into
the pathological head forward position.
The cranium compensates for the
forward head position by rotating the
head posteriorly and assuming an
extended head posture so that normal
line sight is restored. This situation
frequently creates and maintains
entrapment of the occipital nerves
referring pain to the head and face.
TMJ dysfunction will place excessive
demands on the musculature producing
myofascial pain and dysfunction.
Trigger points in the muscles are creat-
ed as a focus of hyper-irritability giving
referred pain to the head and neck.
TMJ dysfunction may be divided into
two categories: trauma and chronic.
The causative factors of each category
and their subsequent treatments are
vastly different and treatment applied to
the wrong category can cause incorrect-
able harm to those who come for
treatment. Insurance companies are
besieged with claims for injuries which
appear to be trauma induced when, in
fact, they are pre-existing conditions
that are non-accident related or exacer-
bations of pre-existing conditions.
Therefore, proper and complete
differential diagnosis and the correct
treatment planning is essential at this
point.
Longus r^
Colli
\ \
STRAIGHTENING OF CERVICAL VERTEBRAE
SCM
SCM
FORWARD HEAD POSITION
Figure 4
The forward position does not allow for normal vision because the cranium is
directing the eyes toward the ground.
— Occipital Nerves
Figure 5
234