by James Jecmen

This article is written as a follow up to the superb article written by J. Thomas Howard, D.D.S. and published in the September 1993 'Journal'.  Dr. Howard provides an excellent overview of the temporal bones and their probable links with pathology.  It is certainly a well established axiom in osteopathy in the cranial field that the temporal bone is a true troublemaker in the head.  It can be said that it is equally associated with malocclusion and is as integral a part of malocclusion as the teeth themselves.  This article will explore some of those interlinks and describe the dental and bony pathology that is associated with temporal 'lesions'.

The temporal bones are paired, and as with all paired bones of the skull, they externally and internally rotate in a rhythmic cycle as the head spine, and indeed entire body go through a cyclic flexion and extension.  Internal rotation causes the squamous portion of the temporal bones to shift medially and slightly posterior, which is followed by external rotation in which the squamous portion moves laterally and slightly anterior.  The mastoid portions move laterally and anterior with internal rotation and medial and posterior with external rotation and during both phases of this normal motion they rotate around an eccentric hub.  The hub or axis is the petrous portion of the temporal bone, a pie-shaped projection that extends medially and anterior from the interior surface of the temporal bone and unites with the occiput and sphenoid bones.  During normal motion of the cranium in flexion, the sphenoid base and occipital base rise toward the vertex of the skull and elevate the tip of the petrous portion of the temporal bone along with them.  So as the skull flexes this elevation of the petrous ridge draws the temporal bone into external rotation and conversely, as it drops, the temporal bone moves into internal rotation.

All this is normal in health.  The total movement of the entire cranial complex of 28 bones and some 135 sutures is very small indeed, but of huge significance in normal physiology.  Without the motion, many abnormal problems can develop, which include, but are by no means limited to, back-up of venous pressure within the calvariun (headaches are a common side effect), entrapment neuropathy of many of the parasympathetic nerves, non-physiologic turn-over of cerebrospinal fluid (CSF), possible blockage of CSF on its movement throughout the ventricles of the brain and spinal cord, swelling of soft tissues, shearing forces around nerves as they pass from one area to another (particularly through intra-cranial foramina), and many other problems.

When a particular bone is unable to cycle from one phase of flexion or extension through its reciprocal movement, it is possible for that bone to become developmentally trapped in that movement pattern with its particular phase of developmental distortion, internal rotation of paired bones is inherent to extension of the head and spine (single bones).  For example, when a person stands tall and pulls the head up and back, tucking the chin in toward the neck, not bending it forward toward the chest, the neck goes into extension.  Extension might best be described as an elongation and narrowing of the organism.  An extension head would be more of a Nordic elongated narrow head than the short rounded or squared Germanic flexion patterned head.  The body follows the some pattern with only very slight lag time as the head and spine change from extension to flexion and back again.

There is one master joint in the skull where this primary flexion and extension seem to be of greatest importance.  It is where the sphenoid and occipital bases unite just anterior and forward of the foramen magnum.  If for some reason this spheno-basilar symphysis (SBS) or union is unable to flex or extend, as might be the case with a significant birth trauma, a blow to the vertex of the skull, a strong impact to the occiput, or even a fall on the buttocks, essentially 'locking' the coccyx in an arrhythmic pattern, then all bones of the head are immediately affected.  This entire system is a reciprocating tension system in which there is equal tension throughout the entire skull and all its bones and internal membranes.  As with one of the basic laws of physics, when there is a force upon an object, there is an equal and opposite force.  The skull is no exception and its intimate function with the entire spinal column makes this system from the skull through the coccyx liable to this reciprocal tension.  In fact, even flexing a toe creates reciprocal tension up to the vertex of the skull!

So, when any one bone is affected, all are affected.  Take the SBS for example, and its reaction to a strong fall on the coccyx.  If the coccyx affects the sacrum so as to preclude it from returning to the extension phase, It remains stuck' in the cranial flexion pattern, created by the fall in which the coccyx repositions ventrally and the sacral base gets 'stuck' dorsally.  The resultant tension placed upon the dural tube (which attaches firmly at the sacrum just above the coccyx) immediately creates non-physiologic tensions within the cranium and cervical spine, The dural attachments act as an anchor to the occiput pulling it into cranial flexion.  If this happens at a young growing age, the constant tension can have as one of its many effects, a tendency to produce a flexion type growth of the occiput.  Given a few years to manifest itself, the occiput develops with the base elevated, ultimately lifting the petrous ridges of the temporal bones bilaterally into external rotation.  If the fall was more on one side of the coccyx, than of equal force on both sides, the result will be an external rotation of one temporal bone and internal rotation of the other.  Or both may be externally rotated, and one, more so than the other.

Let's presume for ease that the fall was of equal intensity on the coccyx bilaterally.  Now the temporals must follow the flexion pattern created in the sacrum which has "pulled' the occiput into flexion ultimately lifting the petrous apexes and externally rotating the temporals.  This results in DIRECT action upon the mandible and teeth.  The temporal bone has multiple influences upon the mandible as with the temporomandibular joint and its ligaments, the temporalis muscle, the masseter, the stylo- mandibular ligament, and others.  The mandible must follow the lead of the temporal bone.  As it does, it moves dorsal and superior to follow the temporal bones, leaving less room for the teeth.  Vertical displacement between the skull and the lower jaw becomes shorter, and the teeth react by crowding, the curve of Spee deepens, ectopic eruption of one or more teeth can occur, and so on. The teeth REACT to problems influencing the entire system as they too are directly influenced by this reciprocal tension system.  When the occiput is stuck in cranial flexion, the temporal bones must externally rotate, the mandible retrudes and elevates, and the teeth display what is on the entire computer.  The 'printout" is the malocclusion. 

With knowledge and understanding of the entire biomechanical system we call man we can interpret this printout of malocclusion as the result of extra-dental forces and develop an appropriate and dedicated plan to reverse the process.  .  . , but that is another article.  The result of such a process described above would be a retrognathic mandible as seen in Class II, division one and Class II, division two.  In one respect I disagree with Dr. Howard's article in that he says bilateral external rotation of the temporal bones is rare, when in fact it is extremely common!

Consider the reciprocal of this flexed occiput/sacrum and go to an extension occiput.  Take for example the child stuck during delivery, in which the occiput will not effectively pass the birth canal as one would hope for during normal delivery.  The occipital base is drawn posterior and inferior resulting in a cranial extension of the occipital base.  Given time to grow in this non-harmonious position, the occiput also draws the first cervical vertebra posterior into what chiropractors call a posterior atlas wedge.  C2 must also mechanically compensate and the result can be an excessive lordosis of the cervical spine.  However, the entire skull suffers as well (not to mention the entire individual).  Many physiologic dysfunctions result from such compression at the base of the brain.  The pons and medulla in particular, suffer from this physical alteration of the nervous system housing.  The centres of respiration are located just inside the foramen magnum and there can be profound alterations of breathing as a result.  Asthma, bronchitis, rhinitis, rhinorrhea, tongue thrusting, neck pain, alterations in behaviour, attention deficit, and fussy or colicky baby can be symptoms associated with this skeletal disharmony.

 

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