Trigeminal Pathways (Stephens)

Question 1

central processes of pseudounipolar neurons in the trigeminal ganglion enter brainstem and these fibers ascend only in the short ascending root of V and terminate _____ these fibers convey what

Answer 1

main sensory nucleus of V

-precise discriminative tactile info from the face

Question 2

fibers adjacent to ascending root course in the ______ which conveys ______ info to main sensory nucleus

Answer 2

mesencephalic tract of V

-proprioception

Question 3

1/2 of fibers that descend only in what tract and terminate where
-convey what fibers

Answer 3

descending root (tract) of V
subnucleus caudalis of descending nucleus of V
-convey pain and temp info from the face

Question 4

the descending root of V is continuous with what

Answer 4

dorsolateral fasciculus of lissaeur in spinal cord

Question 5

where do the secondaries go in precise tactile pathway

Answer 5

from main sensory nucleus:

some cross and go up trigeminal lemniscus and some stay ipsilateral in dorsal trigeminal thalamic tract

Question 6

where do secondary neurons in pain/temp path come from and go

Answer 6

come from subnucleus caudalis, cross midline and ascend as trigeminal lemniscus

Question 7

where do crude tactile fibers go

Answer 7

ascend to main sensory nucleus
descend to subnucleus rostralis and interpolaris
-hard to lose crude tactile to face

Question 8

main sensory nucleus receives what fibers

Answer 8

precise tactile, crude tactile, and proprioceptive info from face

Question 9

descending spinal nucleus of V 3 parts and what terminates here (what info)

Answer 9

subnucleus:
rostralis: tactile info
interpolaris: info from peripheral region of face
caudalis: pain and temperature info from anterior 1/2 of head
-

Question 10

what is the only nucleus in the CNS comprised of pseudounipolar neurons?

Answer 10

mesencephalic nucleus of V

Question 11

what info does mesencephalic nucleus convey

Answer 11

proprioceptive and pressure info from muscles of head and oral region

Question 12

root of fibers to mesencephalic nucleus

Answer 12

peripheral process of pseudounipolar neuron courses with mandibular nerve through trigeminal ganglion and enters brainstem with trigeminal nerve, process ascends towards the mesencephalic nucleus in mesencephalic root of V

Question 13

where does the central process of the mesencephalic nucleus terminate

Answer 13

main sensory nucleus, conscious awareness facial and oral proprioception via TL and DCTT

Question 14

where do other central processes of mesencephalic nucleus terminate

Answer 14

directly upon alpha motor neuron of the trigeminal motor nucleus, this monosynaptic circuit forms jaw-jerk relfex

Question 15

what are the only things that project to the cerebellum

Answer 15

subnuclei rostralis and interpolairs

Question 16

path of subnuclei to cerebellum

-what info

Answer 16

subnuclei R/I project trigeminocerebellar fibers to anterior vermis via ipsilateral inferior cerebellar peduncle
-crude tactile info from head

Question 17

a moderate number of secondary neurons in main sensory nucleus project to anterior vermis of cerebellum via what these fibers convey what

Answer 17

superior cerebellar peduncle

-fibers convey precise tactile and proprioceptive info from head to cerebellum

Question 18

unilateral lesion of trigeminal nerve results in what

Answer 18

anesthesia and loss gen sesations trigem dermatomes
loss jaw jerk reflex
atrophy of muscles of mastication
loss ipsilateral and consensual corneal reflex

Question 19

alternating analgesia

Answer 19

brainstem lesion in upper medulla may destroy primary fibers in descending tract of V and secondary fibers in SL

• ipsilateral hemianalgesia of face
• contralateral hemianalgesia of the body

Question 20

alternating trigeminal hemiplegia

Answer 20

unilateral destruction of trigeminal n and corticospinal tract in pons

• ipsilateral trigeminal anesthesia and paralysis
• contralateral spastic hemiplegia

Question 21

what is trigeminal neuralgia

Answer 21

trigger zone in head may initiate epileptic like discharge from subnucleus caudalis
-intractable lacerating facial pain which follows distribution of affected division of trigeminal nerve