Pupil light relfex

Question 1

What nerve carries the afferent signal to brain stem

Answer 1

Optic Nerve

CN2

Question 2

What nerve carries the efferent motor signal

Answer 2

Parasympathetic nerve fibres associated with oculomotor

CN 3

Question 3

What does a reaction with both eyes suggest

Answer 3

At level of brain stem the motor output is relayed to both pupils

Question 4

What is the information route of light

Answer 4

Photoreceptors in retina
Optic nerve
Brainstem
Pretectal nucleus
Edinger Westphal nucleus on both sides
Sent out
Synapse with ciliary ganglion in orbit of eye
Sent to pupil via parasympathetic nerve fibres running with CN3

Question 5

Finding in L optic nerve damage

Answer 5

Damage to afferent limb
Left direct reflex lost
Neither pupils constrict as signals cannot pass through transected optic nerve

Question 6

Findings with L oculomotor damage

Answer 6

Left direct reflex lost
Right consensual reflex intact
Right direct intact
Left consensual lost