According to the functional matrix theory which is one of the many theories on Growth and Development of the craniofacial region, regardless of normal or not, the craniofacial structure of an individual is influenced by a balance between the
surrounding
skeletal structures including the cranial base, cranial vault, and cervical vertebra and the soft tissues. Head posture may support the equilibration in cranio-cervical region by three musculo-aponeurotic systems which are composed of
intracranial
aponeurotic system, posterior cervical musculo-aponeurotic system, anterior musculo-aponeurotic system. The facial weight suspending to anterior cranial base is transported to posterior cervical muscles by way of two intracranial dural
aponeurotic
system and also it is reacted with anterior musculoaponeurotic system continuing to cranial base form abdominal viscera, hyoid bone and mandible anteriorly and thus, equilibration between craniofacial region and cervical region is accomplished by
tension of these muscles finally.
About the interrelation between head posture and craniofacial morphology, Linder-Aronson have advocated the correlation between the nasopharyngeal airway adequacy and cranio-cervical postural relation, and which is two important biological factor
contributing to craniofactial growth. And Solow and others have postulated the interrelationship between craniofacial morphology, airway adequacy and head posture, and he advocated also that hyoid position relates to craniocervical angle and it
is
contributed to the resting position of mandible and pharynx.
Athanausiou et al. Have studied the relationship between the change of the position of the hyoid and the pharyngeal depth after orthognathic surgery. Wenzel and Fromm-Lundburg have measured the craniocervical angle postoperatively and compared
the
altered maxillofacial structure with the change of head position. The position of the hyoid bone after the alteration of the dentofacial structure through the orthognathic surgery. To study the postoperative relationship, lateral cephalometric
analysis
was done on 117 normal Korean adults(61 males, 56famales) and 41 patients treated by orthognathic surgery.
@ES The following results were obtained:
@EN 1. The craniocervical angle of mandibular prognathism group was smaller than the normal group and significantly increased postoperatively.
2. The craniocervical angle showed a significant relationship with the hyoid bone position in both group.
3. The position of the hyoid bone was more anteroinferiorly positioned in the mandibular prognathism group and moved posteriorly after surgery.
4. The pharyngeal area showed a positive correlation with the pharyngeal depth. There was no significance between the mandibular prognathism group and the normal group. The mandibular prognathism group showed no difference of pharyngeal area
between pre
and postoperation.
Through the above results, the following conclusion was obtained: .
In spite of the change of the craniofacial structure postoperatively, the change of craniocervical angle was harmonized to the change of hyoid bone with one unit, maintaining static airway adequacy.
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