cranial nerves, brain stem reflexes and brainstem disorders Flashcards Preview

MHD > cranial nerves, brain stem reflexes and brainstem disorders > Flashcards

Flashcards in cranial nerves, brain stem reflexes and brainstem disorders Deck (41)
Loading flashcards...
1

CN 1
impairment
permanent loss

impairment: upper respiratory tract infection
permanent:
-head trauma-branches are torn when they pass through the cribriform plate
-tumor near olfactory lobe at the base of skull-such as meningioma

2

superior and inferior recti insert where and do what

superior and inferior oblique insert where and do what

recti: anteriorly, adducts
oblique: posteriorly, abducts

3

superior insertion-superior rectus and superior oblique rotate the eye

bottom insertion-inferior rectus and inferior oblique

superior-medially or inward torsion

inferior-laterally or outward torsion

4

lateral rectus
medial rectus

lateral-abduction
medial-adduction

5

Oculomotor nerve lesion

1. ptosis-levator palpebrae superioris muscle-ipsilateral
2. eye out-unopposed lateral rectus
3. pupil large and unreactive to light directly or consensually

6

CN 4
location
ipsi or contra
defect

only nerve that exits the brainstem dorsally and decussates to innervate the contralateral superior oblique

lesion: Impairment of downward gaze

7

CN 6

ipsilateral rectus muscle-impairment of abduction of the affected eyeball

8

How is binocular diplopia resolved?

coving either eye

9

WHat are somethings that can cause diplopia?

3,4,6 leions
-brainstem or cerebellar lesions

10

What causes monocular diplopia?

looking with one eye alone
-optical system of an eye like dislocated lens or detached retina or psychiatric disorder

11

How can you tell nystagmus from lesions vs nystagmus from drug toxicity?

lesions-more prominent with certain eye movements
drug-symmetrical and present in all eye movements

12

Internuclear ophthalmoplegia (INO)

paralysis of extraocular muscles from a lesion between the nuclei involved with lateral gaze (3 and 6)

13

Gaze right

1. right PPRF must activate
a. right abducens nucleus in the pons
b. left oculomotor nucleus in the midbrain

MLF leaves the right PPRF decussates early and rises to join the left oculomotor nucleus

-->lesion along the main left-sided course of the MLF here en route from pons to midbrain produces paralysis of adduction of left eye with nystagmus of right eye

14

What is the most common cause of MLF lesions?

-multiple sclerosis in younger patients
-ischemic infarction in older patients

15

How does consensual response work in pupillary reflex?

1. retinal ganglion cells project bilaterally to the pretectal area (superior colliculus)
2. then project to the edinger westphal nucleus of 3

16

How does a left optic nerve lesion affect the pupil?

light shined onto left eye neither constrict
light shined on right eye both constrict

17

How does a right CN 3 lesion affect the pupil?

enlarged right pupil never constricts
yet left pupil constricts when light is shined in either eye

18

Relative afferent pupillary defect (RAPD)

partial optic nerve or retinal lesion

swinging plash light test-dilation occurs because of relatively reduced afferent input into the affected eye
-light stimulus produces direct and consensual response but to a lesser degree when the affected eye is stimulated

19

argyll robertson pupils

light-near dissociation seen in neurosyphilis
-accommodate but don't react to light

20

dorsal midbrain (parinaud's) syndrome

pineal tumor compressing the dorsal midbrain but may also occur from ischemic infarction
--->impairment of upward gaze and light-near dissociation of pupils
(MESSED UP 3, down and out and argyll robert pupil)

21

Horner's syndrome

lesion disrupting the oculosympathetic pathway
cuasing
1. miosis
2. anhidrosis
3. mild ptosis

22

Trigeminal nerve 3 divisions

1. V-1 opthalmic
2. V-2 maxillary
3 V-3 mandibular (should not include corner of jaw or neck)

23

V1 sensory impairment + ipsilateral involvment of 3,4,6 may occur from a lesion at what

superior orbital fissure

24

Trigeminal Neuralgia

irritation or inflammation of the trigeminal nerve sensory branches which short circuits or misfires
"electrical shocks" usually V2 or V3

usual cause:
younger: MS lesion of trigeminal nerve entry region into the pons
older: trigeminal nerve branch is often compressed by a tortuous or kinked vessel

25

Lower motor neuron lesion in trigeminal motor nerve

jaw deviating toward lesion

26

upper motor neuron lesion in trigeminal motor nerve one side
vs.
bilateral

one side: no deviation or severe weakness

bilateral: hyperreflexia jaw jerk

27

Each facial nerve innervates the ipsilateral facial muscles, what happens with a lower motor lesion?

severe paralysis of entire ipsilateral half of face

28

Ipsilateral face paralysis + impaired taste over 2/3 tongue

chorda tympani branch involved

29

ipsilateral face paralysis + sensitivity to sound(hyperacusis)

stapedius muscle denervation

30

ipsilateral face paralysis+hyperacusis+hearing impairments and tinnitus

involvment of CN8
-acoustic neuroma

Decks in MHD Class (81):