Abstract

Receptors that convey sensory information about occlusal relationships to the CNS are found in the teeth, periodontal ligaments, muscles of mastication, and the temporomandibular joints. This sensory information enters the CNS largely through the maxillary and mandibular divisions of the trigeminal nerve. Cell bodies of these afferent neurons are found in the trigeminal ganglion (exteroceptive) and mesencephalic nucleus (proprioceptive). Axons of exteroceptive neurons are segregated into those conveying general sensory modalities such as touch, which enter the main sensory nucleus, and those conveying pain and temperature, which descend in the spinal tract of V and enter the spinal nucleus of V. Axons of proprioceptive neurons terminate in the motor nucleus of the trigeminal nerve. Second order neurons of the main sensory and spinal nuclei of the trigeminal nerve project to the thalamus. Third order neurons from the thalamus project bilaterally to the frontal and parietal cortex. The muscles of mastication, responsible for mandibular movement, are innervated by alpha motor neurons from the motor nucleus of V. When these neurons are stimulated, the masticatory muscles contract. The motor nucleus receives fibers from the frontoparietal motor cortex, trigeminal sensory nuclei, cerebellum, contralateral reticular formation, hypothalamus, amygdaloid nucleus, caudate nucleus, tectum of the midbrain, and cranial nerve nuclei (especially VII, which controls the muscles of the mouth and cheek and XII, which controls the musculature of the tongue). Input from all of these areas controls the muscles of mastication through the alpha and gamma motor neurons. Occlusal forces are produced during mastication, swallowing, and other activities. Tooth contacts stimulate sensory neurons. This information is conveyed to the CNS and integrated, and the appropriate adjustment of the mandible is made. Many questions concerning how the nervous system controls occlusion remain unanswered. How do the nervous pathways for the control of occlusal forces differ for individuals with normal occlusion or malocclusion, or for edentulous individuals or those with dentures? If the receptors of the teeth or periodontal ligaments provide the primary sensory input for the muscles of mastication, then clearly the individual with dentures or the edentulous individual must utilize alternative pathways to provide the appropriate control. Why do some people with obvious malocclusion not experience pain and others with minor occlusal problems experience great discomfort in the temporomandibular joint? Perhaps it is genetic, or the pathways used by each of these individuals may differ. What is the effect of repositioning the teeth or the entire jaw on established neuronal pathways? Perhaps the pathways are modified, or they degenerate and other pathways are established.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.