The reasoning: the face has a parallel system
| Trigeminal nucleus | Modality | Note |
|---|---|---|
| Principal (chief) sensory (pons) | discriminative touch | → trigeminal lemniscus (crossed) → VPM |
| Spinal trigeminal (pons → C2) | pain, temperature | descends in spinal tract of V; onion‑skin somatotopy (perioral rostral) → crossed → VPM, intralaminar |
| Mesencephalic | proprioception (jaw muscle spindles) | primary sensory cell bodies inside the CNS — jaw jerk |
| Motor (pons) | muscles of mastication |