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Flashcards in Midbrain (OMG) Deck (26):
1

What muscles of the eye are supplied by CN IV?

Superior oblique

2

What muscles of the eye are supplied by CN III?

- Superior rectus
- Medial rectus
- Inferior rectus
- Inferior oblique
- Levator palpebrae superioris
- Lens and iris supplied by Ciliary ganglion

3

What muscles of the eye are supplied by CN VI?

Lateral rectus

4

Describe the light reflex.

- Photons activate OPTIC NERVE, which synapses on OLIVARY PRETECTAL NUCLEUS
- Activates parasympathetic component of CN III in EDINGER-WESTPHAL NUCLEUS
- Activates ciliary and constrictor pupilae muscles

5

Describe the blink reflex.

- Trigeminal nerve stimulated through mechanical receptors in eye
- Trigeminal senosry nucleus inhibits oculomotor nerve/ levator paplebrae superiorius muscle
- Stimulates facial nerve to contract orbicularis oculi

6

What muscles of the eye are activated by the sympathetic nervous system?

Tarsal muscles

7

What arteries off of the basilar artery supply the midlebrain?

Posterior cerebellar artery:
- Quadrigeminal
- Superior cerebellar artery

8

What structures are affected in Benedikt syndrome?

- CN III nucleus
- Red nucleus
- Corticospinals

In tegementum of midbrain/ cerebellum (median zone)

9

What artery is typically affected in Benedikt syndrome?

- Posterior cerebral artery

10

What are 3 symptoms of Benedikt syndrome?

- Drooping eyelid
- Dilated, nonresponsive pupil
- Contralateral tremor

11

What structures are affected in Weber syndrome?

- Substantia nigra
- Corticospinals/ corticobulbar
- Oculomotor nerve fibers

12

What are 4 symptoms of Weber syndrome?

- Deviation of eye downward and outward
- Drooping eyelid
- Dilated, nonresponsive pupil
- Contralateral UMN paralysis

13

What structure is affected in Oculomotor nerve palsy?

Oculomotor nerve rootlet

14

What are the 3 symptoms of Oculomotor nerve palsy?

- Deviation of eye downward and outward
- Drooping eyelid
- Dilated, non responsive pupil

15

What is Claude's syndrome?

- Weber's syndrome (SN, CS, CB, CN III) +
- Red nucleus
- Cerebellothalamic fibers

16

What are symptoms of Claude's syndrome?

- Deviation of eye downward and outward
- Drooping eyelid
- Dilated, nonresponsive pupil
- Contralateral UMN paralysis
- Contralateral tremor
- Ataxia

17

What is Parinaud's syndrome?

Lesion of posterior tegmentum

18

What is the symptom of Parinaud's syndrome?

Conjugate upward gaze

19

How is the position of the eye affected in Trochlear Nerve Pathology when the eye is:
- Looking straight ahead?
- Looking towards the side of the lesion?
- Looking down?
- Head tilted toward the affected side?

Straight ahead: Contralateral eye elevated due to lack of balance of superior rectus
Toward side of lesion: Contralateral eye elevated due to lack of counter balance to superior rectus
Down: Can't be depressed below midline
Head til: Eliminates diplopia

20

What is the term for patients with trochlear nerve lesions correct their vision by tilting their head toward the affected side?

Bielschowsky's Head Tilt Test

21

What is Argyll-Roberston Pupil?

- Pupil reacts to accommodation/ convergance, but not light
- Pupil is a fixed size, but contracts with accommodation

22

What structure degenerates in Adie's pupil?

- Ciliary ganglia or post ganlionic parasympathetic fibers

23

What reflex is decreased/ absent in Adie's pupil?

- Light reflex

24

How is the pupil affected in Adie's pupil?

- Delayed contraction to near vision
- Delayed dilation in dark

25

Describe the Decerebate position? What is lesioned?

- Lesion below red nucleus
- UE extended
- LE extended

26

Describe the decorticate position. What is lesioned?

- CS tract lesioned
- UE flexed
- LE extended