Neuro: CN Circuitry - 5 And 7 Flashcards
What is CN 5 responsible for:
-somatosensation from face
-muscles of mastication (LMN)
-corneal blink reflex
3 CN 5 sensory nuclei:
-pain, temp, crude touch
-fine touch
-proprioception
1 motor nucleus in CN 5 via LMN go to which muscles:
-temporalis
-masseter
-pterygoids
-tensor tympani (not mastication)
Where is trigeminal motor nucleus located? What does it contain LMN for?
Lateral pons, LMN for muscles of mastication
Mesencepahlic trigeminal nucleus is located where? Responsible for?
-Lateral rostral pons and midbrain
-proprioception
Chief/main/principal trigeminal nucleus is located where? And responsible for?
-Lateral pons
-fine/discriminative touch
Spinal trigeminal nucleus is located where? Responsible for?
-Located in lateral medulla
-pain, temp, crude touch
Trigeminal nerve testing via masseter action:
-clenching
-lateral movement vs resistance
-jaw protrusion
UMN innervation of CN 5:
Supply muscle on the same side, as well as muscles on the contralateral side
Lower motor neurons in CN 5 nucleus supply what?
Ipsilateral muscles
What happens in a LMN lesion on one side of CN 5 nucleus?
Significant weakness in the muscles
What happens if you have an UMN lesion ABOVE CN 5 nucleus?
No significant deficits because of the redundancy of the UMN supply
If you see weakness in muscles involved with CN 5, is it likely UMN or LMN damage? Why?
LMN, because the UMN have redundancy which prevent any significant weakness
Which trigeminal nucleus do pain fibers run through?
Spinal trigeminal nucleus
Which trigeminal nucleus do fine touch fibers run through?
Chief sensory trigeminal nucleus
After synapsing in their respective nuclei, what do the pain and fine touch fibers do/go?
They decussate and travel to thalamus then to cortex
Can there be loss of fine touch receptors while pain receptors are still in tact? Why?
Yes, because they synapse in separate trigeminal nuclei, so damage to one will not impact the other
Where is the facial motor nucleus located?
Lateral portion of pons and CN 7 wraps around CN 6
When testing CN 7 upper face muscles, which muscles are being tested?
Muscles around the eye, orbicularis and frontalis
How to test function of orbicularis muscle
Have pt close their eyes tight
How to test the function of the frontalis muscle
Have the pt raise their eyebrows
When testing CN 7 lower face muscles, which muscles are being tested?
Muscles around the mouth -> have pt try and smile
Do upper and lower facial muscles have the same circuitry?
NO
If there is a lesion on one side to the UMN, where will the deficit/weakness be?why?
-No weakness in upper face
-weakness in the lower contralaterl quarter
-wekaness in lower seen bc only receive input from CONTRAlateral motor cortex
If there is a lesion to the CN 7 nucleus, what deficit/wekaness would be seen? Why?
Weakness on contralteral half of the face
Corneal touch reflex:
-light touch on cornea activate pain receptors
-pain sensory neuron to spinal trigeminal nucleus
-spinal trigeminal nucleus to facial motor nuclei
-bilateral activation of orbicularis oculi
If there is damage seen in palate elevation then the uvula will…
Deviate toward side with intact muscle function
How does an issue with trapezius manifest?
Drooping of shoulder
How do you test sternocleidomastoid function?
Swings the head to opposite side and test strength against examiner’s resistance
Tongue atrophy and fasiculations are LMN signs that indicate damage to:
-hypoglossal nuclei in medulla
-hypoglossal nerve
When testing the hypoglossal nerve using the tongue protrusion test, what happens if there is a lesion?
Tongue deviates towards the weaker side
