Pupillary control - Horner syndrome

Question 1

miosis mechanism - 1st neuron

Answer 1

Edinger-Westphal nucleous to ciliary ganglion via CN III

Question 2

miosis mechanism - 2st neuron

Answer 2

short ciliary nerves to pupillary sphincter muscles

Question 3

pupillary sphincter muscles - receptors

Answer 3

M3

Question 4

A consensual reflex is

Answer 4

any reflex observed on one side of the body when the other side has been stimulated

Question 5

Pupillary light reflex - mechanim

Answer 5

Light in EITHER retina sends signals via CN II (and chiasm and tract) to pretectal nuclei in midbrain that activates bilateral Edinger-Westphal nucleous –> Pupils contract bilaterally (consensual reflex)

Question 6

Pupillary light reflex - direction of the signal from retina to Edinger-Westphal nucleous

Answer 6

light –> retina –> optic nerve optic chiasm –> optic tract –> pretectal nuclei (midbrain) –> bilateral Edinger-Westphal nucleous

Question 7

CN that participate in Pupillary light reflex

Answer 7

optic nerve (CN II)
Oculomotor nerve (CN III)

Question 8

miosis - number of neurons

Answer 8

2

Question 9

mydriasis - number of neurons

Answer 9

3

Question 10

mydriasis - 1st neuron (beginning and end)

Answer 10

hypothalamus to ciliospinal center of Budge (C8-T2)

Synapse in the lateral horn

Question 11

mydriasis - 2nd neuron - direction

Answer 11

exit T1 - travels along cervical sympathetic chain near lung apex, sublavian vessels - superior cervical ganglion

Question 12

mydriasis - 3rd neuron - direction

Answer 12

superior cervical ganglion - plexus along internal carotid through cavernous sinus - enters orbit as LONG CILIARY NERVE - sypathetic fibers also innervate smooth muscle of eyelids (minor retractors) and sweat glands of forehead and face

Question 13

mydriasis - 3rd neuron - innervate

Answer 13

1. pupillary dilator muscle
2. smooth muscle of eyelids (minor retractors)
3. sweat glands of forehead and face

Question 14

mydriasis - 3rd neuron is going through

Answer 14

cavernous sinus

Question 15

long vs short ciliary nerve - according to eye control

Answer 15

long: 3rd neuron of Mydriasis
short: 2nd neuron of Miosis

Question 16

Marcus Gunn pupil - clinical finding

Answer 16

decreased bilateral pupillary constriction when light is shone in affected eye relative to unaffected eye

Question 17

Marcus Gunn pupil - mechanism

Answer 17

Afferent pupillary defect due to optic nerve damage or severe retinal injury

Question 18

Marcus Gunn pupil is tested with

Answer 18

swinging flashlight test

Question 19

Some causes of Horner syndrome

Answer 19

1. spinal cord above T1: Brown-Sequard syndrome (cord hemisection), Late stage syringomegalia
2. Pancoast tumor
3. Lateral medullary (Wallenberg) syndrome
4. Infernal carotid dissection
5. Carvenous sinus syndrome

Question 20

Horner syndrome - findings

Answer 20

1. ptosis
2. anhidrosis and flushing
3. Miosis

Question 21

Area of pretectal nucleus

Answer 21

Upper midbrain

Question 22

Long ciliary nerve is going to the eye next to

Answer 22

V1 (opthalmic division of trigeminal nerve)

Question 23

Superior tarsal muscle is AKA

Answer 23

Müller’s muscle.