Cranial nerves Flashcards
The trochlear nerves cross what areas of the brain on their way to the superior oblique muscle?
cross the superior medullary velum before emerging from the dorsal surface of the brainstem.
How can you remember the position of the trochlear nerve in relation to the abducens nerve on the pons?
Trochlear nerve is on chocolate mountain on top of the pons and the abducens is on the patrick the starfishes belly
Oculomotor palsy would present with what likely causes and what likely PE?
causes think BLOOD- diabetic ischemia, HTN, malignancy, head trauma, aneurysm.
PE- ptosis, down and out gaze (lateral strabismus), dilated pupil, and nearsighted problems.
abducens nerve is found on the floor of what?
fourth ventricle
whats esotropia the result of?
It’s medial deviation of the eye resulting from a lesion to the abducens nerve resulting in the unopposed action of the medial rectus muscle.
my abs esooo sexy
What are some functions of the facial nerve other than sensation of the face?
orbicularis occuli muscle to close the eyes
Mucus formation, tears, saliva, taste, and hearing
Between the geniculate ganglion and the stylomastoid foramen is an area where neurologic injury can lead to what pathology?
bells palsy
What muscles are innervated by CN VII?
to zanzibar by motor car
temporal, zygomatic, buccal, mandibular, and cervical
How will an UMN vs LMN lesion affect CN VII differently?
UMN (supra nuclear lesion) will cause paralysis on the lower half of the face (below the eye) because the upper face is innervated by both hemispheres and not affected by the lesion. So a typical stroke patient will not have to have surgery to keep their eyelid closed.
A LMN lesion (CN VII) in Bells palsy will cause ipsilateral facial paralysis and the inability to close the eye tight. The chords tympani nerve may also be impaired leading to lack of tears, saliva, and taste.
Hypoglossal nerve XII supplies what side of the lounge if it originates in the left hemisphere? If paralyzed on this side, in which direction will the lounge deviate? If the tongue is atrophied and fasciculating this indicates what?
left side
to the left side
LMN lesion
The causes of this are rare and ominous
UMN spastic
Acronyms coppola AION, PION, CRAO
acute ischemic optic neuropathy
progressive ischemic optic neuropathy
central retinal artery occlusion (artery runs next to optic nerve and feeds the retina)
If a patient presents with AION, PION, CRAO or diplopia with headache and they’re over 50 y/o what should you do?
ESR, CRP to screen for GCA even if optic disk is normal b/c it could be PION. Treat immediately with steroids don’t wait for labs
Patient has ptosis and a down and out gaze with a dilated un-reactive pupil what should you do and what is the most likely cause? How do things change if the pupil is reactive?
Get stat MRI and MRA and maybe CTA and LP
This is likely caused by an aneurysm usually of the posterior communicating artery PCA; could also be MG.
If the pupil is reactive you can wait and watch it for changes
How might a midbrain stroke affect CN III? What should you do?
progressive palsy that requires immediate action and MRI MRA
Patient presents to you with strange gait and seems confused. Your fundoycopic exam reveals abnormal movement. You’re not sure how to classify this because you know this patient is drunk a lot, although they appear sober at the moment. What vitamin deficiency is characteristic of the patients most likely diagnosis? What other conditions or treatments can cause this deficiency?
Thiamine
Wernickes encephalopathy
Other causes-bariatric surgery, re-feeding syndrome from those experiencing starvation….
