Pupils

Question 1

Which nerve mediates pupil constriction/

Answer 1

oculomotor nerve (CN III)

Question 2

What is responsible for pupil dilatation?

Answer 2

Sympathetic nervous system via the ciliary nerves

Question 3

What is relative afferent pupillary defect?

Answer 3

aka Marcus gunn pupil
swinging light - affected pupil dilates when swinging light to affected eye when it should constrict - signifies lesion anterior to optic chiasm i.e. optic nerve or retina

Question 4

What are causes of RAPD>?

Answer 4

Optic nerve - optic neuritis e.g. MS

Retina detachment

Question 5

describe the afferent pathway of pupillary light reflex

Answer 5

retina → optic nerve → lateral geniculate body → midbrain

Question 6

Describe efferent pathway of pupillary light reflex

Answer 6

Edinger Westphal nucleus (midbrain) -> oculomotor nerve

Question 7

What is Horners syndrome?

Answer 7

disruption of the sympathetic nerves supplying the eye

Question 8

What are the features of Horners syndrome?

Answer 8

1. Partial ptosis - upper eyelid drooping
2. Miosis - pupillary constriction -> difference in pupil size
3. Hemifacial anhidrosis (no sweat)

Question 9

What are the causes of Horners syndrome?

Answer 9

1. Central - stroke, syringomyelia, MS, tumour, encephalitis
2. Pre-ganglionic lesions- pan coasts tumour, thyroidectomy, trauma, cervical rib
3. Post-ganglionic - carotid artery dissection, carotid aneurysm, cavernous sinus thrombosis, cluster headache

Question 10

What lesions cause no anhidrosis in horners syndrome?

Answer 10

post-ganglionic lesions