neuro cortex - opthalmology

Question 1

what does the optic tract connect?

Answer 1

the optic chaism to the lateral geniculate nuclei

Question 2

what is the function of the optic tract?

Answer 2

conveys signals from the contralateral nasal retina and the ipsilateral temporal retina
- fibres that serves the afferent limb of the pupillomotor reflex exit the optic tract to terminate in the pretechtal nuclei in the midbrain, which then project to the edinger-westphal nuclei

Question 3

where is the occulomotor nucleus located?

Answer 3

in the dorsal midbrain at the level of the superior colluculus

Question 4

what does the inferior oblique do?

Answer 4

extorsion, elevation and abduction of the eye

Question 5

what does the inferior rectus do?

Answer 5

depression of the eye

Question 6

what does the medial rectus do?

Answer 6

adduction of the eye

Question 7

what does the superior rectus do?

Answer 7

elevation of the eye

Question 8

what does the levator muscle do?

Answer 8

retraction of the eyelid

Question 9

where are the trochlear nuclei found?

Answer 9

in the midbrain at the level of the inferior colliculus

Question 10

what does the trochlear nerve innervate? which muscle of the eye?

Answer 10

the contralateral SO muscle

Question 11

which is the smallest CN ?

Answer 11

trochlear

Question 12

where is the abducens nucleus located?

Answer 12

in the pontine tegmentum ventral to the fourth ventricle

Question 13

what is the basic pathway of the pupillary light reflex?

Answer 13

• light enters eye
• signal sent ot optic nerve
• signal exits optic tract to the ipsilateral pretechtal nucleus in the midbrain
• pretechtal nucleus projects bilateral signals o both EW nuclei
• pre-ganglionic parasympathetic fibres from EW travel along occulomotor nerve then exit and synapse with post-ganglionic neurones in the ciliary ganglion
• from ciliary ganglion, tthe para fibres are carried via the short ciliary nerves to innervate the ciliary muscle and sphincter pupillae (constrictor)

Question 14

what is neuromyelitis optica (Devic’s disease)?

Answer 14

• demyelinating disorder charcterised by bilateral severe optic neuritis and transverse myeliis in 3 or more vertebral columns
• IgG antibody against AQP4 can be found

Question 15

what is anterior ischaemic optic neuropathy? (AION)

Answer 15

• occurs due to damage to the optic nerve as a result of ischaemia
• it is a common cause of optic neuropathy in the elderly group

Question 16

what is lateral medullary syndrome? (wallenberg’s syndrome)?

Answer 16

• ischaemia to the lateral part of the medulla oblongata due to blockage of the posterior inferior cerebellar artery or vertebral artery

Question 17

what is Adie’s pupil?

Answer 17

charcterised by loss of postganglionic parasympathetic inversion to the iris spinchter and ciliary muscle (damage to ciliary ganglion)
- unilateral and young females

Question 18

what is argyll robertson pupil?

Answer 18

• bilateral, irregular and small pupils

- both pupils do not react to light, however, they consrict normally on accommodation

Question 19

symptoms of large pituitary adenoma?

Answer 19

bitemporal hemianopia

Question 20

symptoms of craniophayngioma?

Answer 20

• bilateral hemianopia, growth failure, delayed puberty, headaches, DI, obesity, hypothydroidism in children

Question 21

what are the symptoms of tuberculum sellae meningioma?

Answer 21

lesion is at the anterior angle of chiasm causing a junctoinal scrotomas

Question 22

what are the symptoms of optic tract lesion?

Answer 22

contralateral homonymous hemianopia

Question 23

what are the symptoms of a temporal radiation lesion?

Answer 23

contralateral superior homonymous quadrantanopia

“pie in the sky”

Question 24

what are the symptoms of a parietal radiation lesion?

Answer 24

contralateral inferior homonymous quadreantanopia “pie in the floor”

Question 25

what are the symtoms of a main radiation lesion?

Answer 25

contralateral homonymous hemianopia

Question 26

what are the symptoms of occlusion of the calcarine artery of the posterior cerebral artery?

Answer 26

contralateral homonymous hemianopia with macular sparing

Question 27

what are the symptoms of damage to the tip of the occipital cortex in a posterior head injury?

Answer 27

congruous homonymous macular defects

Question 28

what is weber’s syndrome?

Answer 28

form of stroke affecting the ventral midbrain

- characterised by ipsilateral 3rd nerve palsy within contralateral hemiparesis (cerebral peduncle)

Question 29

what is Benedikt’s syndrome?

Answer 29

a form a stroke affecting the dorsal midbrain, characterised by ipsilateral 3rd nerve palsy with contralateral tremor, ataxia or chorea (red nucleus)

Question 30

symptoms of 4th nerve palsy?

Answer 30

vertical diplopia (worse on walking downstairs or looking down)

Question 31

symptoms of 6th nerve palsy?

Answer 31

horizontal double vision - worse on looking at distant targets

Question 32

what is benign essential blepharospasm?

Answer 32

bilateral idiopathic condition charcterised by involuntary contraction of the orbicularis oculi muslce
- 6th decade of light

Question 33

what are the cavernous sinuses?

Answer 33

large connections of veins in the head, located lateral to the sella turcica and posterior to the superior orbital fissue
the lateral wall of th esinus contains cranial nevres 3,4 and 5 (V1, 2) while the ICA and CN 6 pass through the cavernous sinus

Question 34

what are the features of cavernous sinus syndrome?

Answer 34

• ptosis and opthalmoplegia (Due to compression of 3,4,6)
• loss of corneal reflex
• maxillary sensory loss - due to CN 5 V2
• horner’s syndrome
• proptosis and periorbital swelling