Dysfonctionnements musculaires douloureux de l'appareil manducateur et dysfonctionnements cervicaux et linguaux connexes (3e partie)

Abstract

According to the "pain adaptation model", temporomandibular disorder (TMD) pain induces a paradoxical activity of masticatory muscles: an agonistic hypoactivity during jaw closing and a weak antagonistic activity during jaw opening (agonist/antagonist co-activation); the pain-induced motor regulation implies the segmental trigeminal (V) motor system and/or CPG. This model has been extended to other types of musculoskeletal disorders (MSD). However, despite its power, this model does not fit with all types of neck muscle activities in neck pain. This discrepancy may be due: to the complexity of the cervical spine (with its numerous agonist, antagonist and synergist muscles), and to the specificities of the cervical neuromuscular system in interrelationships with the control of body and head posture, the patency of the upper airway depending on head/cervical posture, the neck and arm/shoulder muscles' activity, and finally, the neck and masticatory muscles' activity. Besides pain, psychological stress may induce motor dysfunction in MSD (e.g. kinesiophobia, difficulty switching off). Finally, it is hypothesised that tongue dysfunction could be connected to TMD (due to intersegmental coordination between V, VII and XII motor nuclei): the weakness of the agonistic activity of masticatory muscles would favour immature deglutition, where facial muscle (VII) activity predominates over masticatory muscle (V) activity.