Neuro Pupil Control Tutorial

Front 1

Afferent pathway of the pupil reflex

Back 1

Optic: Axons may arise in optic tract or above it, but pass without synapsing in LGN and synapse directly in pretectal area of brainstem.
Brainstem: Neurons from pretectal project to ipsilateral E-W nucleus AND via post commissure to contra pretectal and E-W nucleus (Direct and consensual response)

Front 2

Efferent pathway of the pupil reflex

Back 2

Parasym from E-W to ciliary ganglion where they synapse, ultimately innervating pupillary sphincter (miosis)

Front 3

What kind of receptors are in the synapses of pupil reflex?

Back 3

Muscarinic

Front 4

Major responsibilities of CN III

Back 4

Carry pupillary reflex neurons, raise eyelid, extraocular eye movement (MR, IR, SR, IO)

Front 5

Pupil symptoms in R CN III damage (efferent), for example

Back 5

1. R pupil dilated at rest
2. R will not show consensual response
3. R will not show direct response (while L will be consensual)
4. Mild outward deviation
5. Ptosis

Front 6

Pupil symptoms in R retinal/optic damage (afferent), for example

Back 6

1. Normal at rest
2. R consensual intact
3. R direct will have no response and no L consensual response

Front 7

Accomodation-Convergence reflex

Back 7

Convergence is mediated by CN III (medial rectus), while accomodation is increased sphericity and pupillary constriction parasym mediated by E-W nucleus
--Essentially all visual pathways must be intact

Front 8

Pupillary dilation (sympathetic) pathway

Back 8

Hypothalamus -> lateral brainstem (congruent with ALS) -> T1-T2 -> SYNAPSE in lateral horn -> ascend to superior ganglion -> carotid plexus -> pupillary dilator muscle/superior tarsal (involuntary opening of the eyes)

Front 9

Horner's Syndrome. Symptoms?

Back 9

Interruption of sympathetic facial innervation.
Ptosis, miosis, anhydrosis

Front 10

What happens to pupil when CN III is damaged?

Back 10

The sympathetic innervation wins, resulting in constant dilation of ipsilateral eye

Front 11

What happens in damage to the accomodation-covergence reflex (neuro degeneration)

Back 11

Light pupillary response is lost, but accomodation is usually intact? (31-28)