Eyelids

Question 1

How does tactile stimuli trigger blinking?

Answer 1

Brainstem via 5th and 7th cranial nerves
Does not require corical input

Question 2

What can cause reflex blinking?

Answer 2

Optical
Auditory
Tactile stimuli

Question 3

Which fibres of orbicularis oculi initiate reflex blinking?

Answer 3

Pretarsal

(not orbital)

Question 4

What tumours can cause loss of cornea reflex?

Answer 4

CPA tumours

Question 5

When does spontaneous blinking devleop?

Answer 5

2rd month of life

Question 6

How long is blink?

Answer 6

0.3secs

15/min

Question 7

What is bell’s phenomenon

Answer 7

Upward movement of the globe associated with eye closure

Question 8

hat is the Marcus Gunn syndrome?

Answer 8

Caused by levator palpebrae superioris and pterygoid muscle linkage

Jaw winking

Question 9

How does guanetheidine work?

Answer 9

Inhibit release of noradrenaline from nerve terminals

Inhibits action of Muller’s msucle
Decrease palpebral fissure width

Question 10

How does botox reduce blepharospasm?

Answer 10

Inhibitis presynaptic acetylcholine release
Decrease neuromsuclar transmission

Question 11

How does Tensilon test work? What is it for?

Answer 11

Diagnosis of myasthenia gravis

Anticholinergic action of edrophonium at NMJ increases ACh concentration at the junction

Question 12

Why does cocaine not affect the ptosis in Horner’s?

Answer 12

Prevents reuptake of noradrenaline but will enhance sympathetic activity only if there is an in tact sympathetic chain to initiate release of noradrenaline