What is the neuroanatomy of the trigeminal nerve relevant to burning mouth syndrome (BMS)?

Updated: Apr 15, 2021
  • Author: Vincent D Eusterman, MD, DDS; Chief Editor: Arlen D Meyers, MD, MBA  more...
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The trigeminal nerve enters the brainstem at the pons and bifurcates in the principal sensory nucleus. There, the different types of fibers in the trigeminal nerve follow different courses, as follows:

  • Discriminatory tactile fibers synapse in the principal sensory nucleus, cross midline, and ascend in the medial lemniscus to the ventroposterior medial nucleus of the thalamus (VPM).

  • Afferent proprioceptive fibers of V3 from masticatory muscles (masseter, temporalis, medial and lateral pterygoids) pass through the principal sensory nucleus. Their cell bodies are located in the mesencephalic nucleus superior to the principal sensory nucleus, and they synapse in the motor nucleus medial to the principal sensory nucleus.

  • Nociceptive (pain and temperature) fibers pass through the principal sensory nucleus and descend before synapsing in the large spinal trigeminal nucleus of the medulla. The spinal nucleus contains 3 subnuclei from cranial to caudal: oralis, interpolaris, caudalis. Generally, pain fibers synapse in the subnucleus caudalis prior to crossing and ascending in the spinothalamic tract.

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