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Spinal trigeminal nucleus

The spinal trigeminal nucleus is a major sensory nucleus of the trigeminal nerve responsible for processing pain, temperature, and crude touch sensations from the face. It is functionally analogous to the spinothalamic tract of the body and forms part of the trigeminal sensory system.

This nucleus extends longitudinally through the brainstem and upper cervical spinal cord and is a key anatomical landmark in brainstem neuroanatomy and imaging.

Synonyms

  • Spinal nucleus of the trigeminal nerve

  • Nucleus of the spinal tract of trigeminal nerve

Location

  • Extends from the caudal pons through the medulla

  • Continues inferiorly into the upper cervical spinal cord (C2–C3 levels)

  • Located in the dorsolateral brainstem

  • Lies medial to the spinal trigeminal tract

  • Situated posterior to the inferior olivary nucleus (medullary level)

Anatomical course

  • Primary afferent fibers:

    • Enter the brainstem at the pons via the trigeminal nerve

    • Descend ipsilaterally as the spinal trigeminal tract

  • Nucleus:

    • Receives descending pain and temperature fibers from the face

    • Organized longitudinally into subnuclei (oralis, interpolaris, caudalis)

  • Second-order neurons:

    • Project contralaterally as the trigeminothalamic tract

Relations

Anteriorly:

  • Inferior olivary nucleus (medulla)

  • Reticular formation

Posteriorly:

  • Inferior cerebellar peduncle

Medially:

  • Nucleus ambiguus (medullary level)

Laterally:

  • Spinal trigeminal tract

Structures conveyed

  • Pain sensation from the face

  • Temperature sensation from the face

  • Crude (non-discriminative) touch from facial structures

Function

  • Facial pain processing: Receives nociceptive input from facial skin and mucosa

  • Thermal sensation: Processes facial temperature information

  • Protective sensory role: Contributes to reflexive responses to noxious facial stimuli

  • Sensory integration: Works alongside the principal sensory trigeminal nucleus

MRI appearance 

T1-weighted images:

  • Spinal trigeminal nucleus: Isointense to surrounding brainstem gray matter

  • Margins: Not individually delineated; identified by anatomical location

T2-weighted images:

  • Normal nucleus: Intermediate signal intensity similar to adjacent gray matter

  • Symmetry: Bilateral and symmetric appearance

FLAIR:

  • Normal: Homogeneous signal with limited conspicuity

Diffusion-weighted imaging (DWI):

  • Normal: No diffusion restriction

  • Configuration: Elongated vertical structure along the brainstem axis

Post-contrast T1-weighted images:

  • Normal: No enhancement

CT appearance

Non-contrast CT:

  • Spinal trigeminal nucleus: Not individually visualized

Post-contrast CT:

  • Normal: No focal enhancement attributable to the nucleus

MRI images

MRI Spinal trigeminal nucleus (pars caudalis) axi anatomy image -img-00000-00000

MRI images

MRI Spinal trigeminal nucleus (pars oralis) axial anatomy image -img-00000-00000

MRI images

MRI Spinal trigeminal nucleus (pars oralis) axial anatomy image -img-00000-00000_00001