Ascending pathway of Trigeminal system Flashcards
Trigeminal nuclear complex extends
from the midbrain to the spinal cord
3 dermatomes of trigeminal
V1- opthalmic
V2- Maxillary
V3- Mandibular
3 regions of the trigeminal in the medulla
nucleus oralis
nucleus interpolairis
nucleus caudalis
Three sensory modalities are segregated in the sensory nucleus complex
Mesencephalic - proprioceptive (midbrain), contains pseudounipolar neurons and do NOT go through the trigeminal ganglion.
Main sensory- vibrotactile discrimination (Pons)
Spinal trigeminal - pain, temperature (medulla)
The ventral trigeminothalamic tract (spinotrigeminal) transmits
nociceptive info of the head
trigeminal nerve come into the central nervous system at what level of the brainstem?
mid pons
Ventral Trigeminothalamic tract
Type of information in pathway: Pain, temperature
Point of origin, receptors involved: Free nerve endings (TRP channels) in skin, viscera, muscles
Where primary cell bodies are located: trigeminal/semilunar/gasserian ganglion
Where 1st synapse is: Spinal trigeminal nucleus (somatotopic organization)
Where in Brainstem it enters, travels: Pons, descends to spinal trigeminal nucleus (“Spinal trigeminal tract”) in medulla
Where/if it decussates: Internal arcuate fibers in medulla
Where second synapse is: Ventral posterior medial nucleus (VPM) of the Thalamus.
Final destination: Primary somatosensory cortex (via internal capsule and corona radiata)
Trigeminal neuralgia
is communicated through the ventral trigeminal pathway
paroxysmal attacks of pain lasting from a fraction of a sectnd to 2 minutes, affecting one or more divisions of the trigeminal nerve
“tic douloureux”
Most common in maxillary div
Vascular compression
Right side more commonly affected
Nociceptive input around the meninges is carried by
different branches of CN V
most meninges are felt as pain around the eyes. (V1)
The trigeminocardiac reflex can be carried via
the spinotrigeminal tract
During neurosurgery, complication from massive parasympathetic response:
decreased Heart Rate
decreased Blood Pressure
decreased Respiration Rate
The diving reflex of mammals produces the same response when the face is submerged in cold water
MSN/ML and Dorsal Trigeminothalamic tract
Type of information in pathway: Tactile discrimination, Point of origin, receptors involved: Meissner’s corpuscles, merkel’s disks, pacinian corpuscles, ruffini’s endings
Where primary cell bodies are located: trigeminal/semilunar/Gasserian.
Where 1st synapse is: Main sensory nucleus
Where in Brainstem it enters, travels: Pons, ascends contralaterally and ipsilaterally (for oral cavity).
Where/if it decussates: In pons, ascends with medial lemniscus
Where second synapse is: Ventral posterior medial nucleus (VPM) of the Thalamus.
Final destination: Primary somatosensory cortex (via internal capsule and corona radiata)
Basic touch info of the head ascends
bilaterally in two pathways
oral cavity ascends ipsilaterally
proprioceptive input enters the brain at… and ascends…
the pons and ascends to the midbrain
Mesencephalic nucleus of V.
This region contains pseudounipolar cell bodies
From the Mes. Nuc V:
Cerebellum (Proprioceptive)
Vestibular nuclei (proprioceptive, reflex)
Reticular formation (change behavioral state)
Motor nucleus of V (Jaw-jerk reflex)
Facial motor nucleus (Primary-gaze frontalis reflex)
proprioceptive info to the face often linked in a reflex arc
important in preventing ptosis, raising eyebrows
