Exam 3: Trigeminal pathways Flashcards
What is the visceral body’s equivalent to the trigeminal nerve?
spinal nerve and the dorsal root ganglia
What are some pain syndromes associated with the trigeminal nerves?
TM disorders, Earaches, headaches, toothache, sinus pain, trigeminal neuralgia
Is afferent input from the trigeminal nerve contralateral or ipsilateral? What about intra/contra projections to thalamus?
Ipsilateral from: face, top of head, eardrum, anterior 2/3rd of tongue (NOT TASTE), proprioception of jaw. Project contralaterally to the thalamus
Is efferent motor output for the trigeminal nerve contralateral or ipsilateral?
Ipsilateral to: muscles of mastication, tensor tympani
What are the 3 central trigeminal sensory nuclei?
Mesencephalic, main sensory, spinal (descending) trigeminal
What is the main sensory nuclei of trigeminal nerve responsible for?
fine touch, vibration
What is the spinal (descending) trigeminal nuclei responsible for?
Pain and temperature
Where do mechanoreceptor nerves of CN-V route to?
chief sensory nuclei, also descent in spinal tract of V to spinal nucleus of V
What nucleus is in charge of proprioception of jaw muscles from the trigemincal nuclei?
Mesencephalic nuclei
T/F: cell bodies of CN V mesencephalic nuclei are located in the CNS
true
Where do mechanoreceptors of trigeminal ganglia synapse? and where does 2nd order neuron go to?
Main sensory nucleus, crosses and goes up via ventral trigeminal thalamic tract and oral cavity travels up dorsal trigeminal thalamic tract (ORAL ONLY- ipsilaterally)
Where do nociceptors of trigeminal ganglia synapse? where does the 2nd order neuron go?
1st order neuron descends down CN V spinal tract, synapses with spinal nucleus of V, 2nd order crosses and move up collectively with ventral trigeminal thalamic tract to the ventral posteromedial thalamus (face)
What does a tractotomy of the spinal tract of CN-V result in?
ipsilateral pain relief of the face/head
What kind of neurons are typically found in spinal trigeminal nucleus?
Mostly nociceptive 2nd order neurons with some tactile
Where do second order neurons of the spinal trigeminal nucleus project to?
ventral posteriomedial thalamus via the ventral trigeminothalamic tract (VTT)
What structure is the ventral trigeminothalamic tract running closest to for the rest of the bodies sensation?
STT (medial leminiscus in some regions)
In relation to the chief sensory nucleus of V, where is the motor nucleus of V?
Medial
What is the main input to the main sensory nucleus of V?
Mechanoreceptors
Where do second order neurons of the main sensory nucleus of V project to?
Contralateral VPM thalamus (joins the VTT)
Where does oral mechanoreception of the chief sensory nucleus project to?
ipsilateral VPM via the dorsal TT
What is the somatotopic organization of the VPM?
face projections lateral to nucleus, taste projections medial, intraoral projections in between the two
Where do neurons of the mesencephalic trigeminal nucleus receive input from?
Proprioceptors receive input from stretch receptors in periodontium and muscles of mastication
What kind of neuron (multipolar, unipolar, etc) is found within the mesencephalic trigeminal nucleus?
pseudounipolar neurons
Where do axons of neurons of the mesencephalic trigeminal nucleus project to?
Motor nucleus of V (involved in monosynaptic Jaw Jerk reflex)
What kind of junction is found between neurons of motor nucleus of V (second order to mesencephalic trigeminal nucleus cells) and muscles?
Neuromuscular junction
What neurotransmitter is released at the neuromuscular junction of motor cells of motor nucleus of V? What kind of receptor does it interact with?
Acetylcholine and nicotinic receptors
What would be the impact of damage to the motor nucleus of V and its efferent fibers to the muscles of mastication?
Ipsilateral weakness
