Exam 3: Trigeminal pathways

Question 1

What is the visceral body’s equivalent to the trigeminal nerve?

Answer 1

spinal nerve and the dorsal root ganglia

Question 2

What are some pain syndromes associated with the trigeminal nerves?

Answer 2

TM disorders, Earaches, headaches, toothache, sinus pain, trigeminal neuralgia

Question 3

Is afferent input from the trigeminal nerve contralateral or ipsilateral? What about intra/contra projections to thalamus?

Answer 3

Ipsilateral from: face, top of head, eardrum, anterior 2/3rd of tongue (NOT TASTE), proprioception of jaw. Project contralaterally to the thalamus

Question 4

Is efferent motor output for the trigeminal nerve contralateral or ipsilateral?

Answer 4

Ipsilateral to: muscles of mastication, tensor tympani

Question 5

What are the 3 central trigeminal sensory nuclei?

Answer 5

Mesencephalic, main sensory, spinal (descending) trigeminal

Question 6

What is the main sensory nuclei of trigeminal nerve responsible for?

Answer 6

fine touch, vibration

Question 7

What is the spinal (descending) trigeminal nuclei responsible for?

Answer 7

Pain and temperature

Question 8

Where do mechanoreceptor nerves of CN-V route to?

Answer 8

chief sensory nuclei, also descent in spinal tract of V to spinal nucleus of V

Question 9

What nucleus is in charge of proprioception of jaw muscles from the trigemincal nuclei?

Answer 9

Mesencephalic nuclei

Question 10

T/F: cell bodies of CN V mesencephalic nuclei are located in the CNS

Answer 10

true

Question 11

Where do mechanoreceptors of trigeminal ganglia synapse? and where does 2nd order neuron go to?

Answer 11

Main sensory nucleus, crosses and goes up via ventral trigeminal thalamic tract and oral cavity travels up dorsal trigeminal thalamic tract (ORAL ONLY- ipsilaterally)

Question 12

Where do nociceptors of trigeminal ganglia synapse? where does the 2nd order neuron go?

Answer 12

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)

Question 13

What does a tractotomy of the spinal tract of CN-V result in?

Answer 13

ipsilateral pain relief of the face/head

Question 14

What kind of neurons are typically found in spinal trigeminal nucleus?

Answer 14

Mostly nociceptive 2nd order neurons with some tactile

Question 15

Where do second order neurons of the spinal trigeminal nucleus project to?

Answer 15

ventral posteriomedial thalamus via the ventral trigeminothalamic tract (VTT)

Question 16

What structure is the ventral trigeminothalamic tract running closest to for the rest of the bodies sensation?

Answer 16

STT (medial leminiscus in some regions)

Question 17

In relation to the chief sensory nucleus of V, where is the motor nucleus of V?

Answer 17

Medial

Question 18

What is the main input to the main sensory nucleus of V?

Answer 18

Mechanoreceptors

Question 19

Where do second order neurons of the main sensory nucleus of V project to?

Answer 19

Contralateral VPM thalamus (joins the VTT)

Question 20

Where does oral mechanoreception of the chief sensory nucleus project to?

Answer 20

ipsilateral VPM via the dorsal TT

Question 21

What is the somatotopic organization of the VPM?

Answer 21

face projections lateral to nucleus, taste projections medial, intraoral projections in between the two

Question 22

Where do neurons of the mesencephalic trigeminal nucleus receive input from?

Answer 22

Proprioceptors receive input from stretch receptors in periodontium and muscles of mastication

Question 23

What kind of neuron (multipolar, unipolar, etc) is found within the mesencephalic trigeminal nucleus?

Answer 23

pseudounipolar neurons

Question 24

Where do axons of neurons of the mesencephalic trigeminal nucleus project to?

Answer 24

Motor nucleus of V (involved in monosynaptic Jaw Jerk reflex)

Question 25

What kind of junction is found between neurons of motor nucleus of V (second order to mesencephalic trigeminal nucleus cells) and muscles?

Answer 25

Neuromuscular junction

Question 26

What neurotransmitter is released at the neuromuscular junction of motor cells of motor nucleus of V? What kind of receptor does it interact with?

Answer 26

Acetylcholine and nicotinic receptors

Question 27

What would be the impact of damage to the motor nucleus of V and its efferent fibers to the muscles of mastication?

Answer 27

Ipsilateral weakness