Autonomic Reflexes of the Eye

Question 1

what parts of the face does CNV1 (ophthalmic) provide sensory innervation for?

Answer 1

upper eyelid
cornea
conjunctiva

via the supraorbital nerve and nasal skin branches (consider shingles)

Question 2

what parts of the face does CNV2 (maxillary) provide sensory innervation for?

Answer 2

skin of the lower eyelid
skin over maxilla

via the infraorbital nerve

Question 3

what parts of the face does CNV3 (mandibular) provide sensory innervation for?

Answer 3

skin over mandible and TMJ, except angle of mandible

Question 4

what is the corneal reflex

Answer 4

blinking

Question 5

sensory (afferent) role of the corneal reflex

Answer 5

AP conducted along CNV1 from the cornea to trigeminal ganglion along CNV

Question 6

central CNS connection in the corneal reflex

Answer 6

pons for CNV to CNVII

Question 7

motor (efferent) role of the corneal reflex

Answer 7

APs conducted via CNVII to orbicularis oculi

Question 8

what does sympathetic innervation do to the eye?

Answer 8

opens eyes wider
gets more light into the eye
focuses on far objects

Question 9

what does parasympathetic innervation do to the eye?

Answer 9

gets less light in (protection from bright light or when asleep)
focuses on near objects
reflex lacrimation (wash away stimulant foreign body and cleans cornea)

Question 10

role of the vestibulo-ocular reflex

Answer 10

eyes turn in opposite direction to head movement

stabilises gaze

Question 11

CNS connections in the vestibulo-ocular reflex

Answer 11

CNVIII and CNs III, IV and VI

Question 12

role of the oculocardiac reflex

Answer 12

reflex bradycardia in response to tension in extraocular muscles or pressure on the eye- aims to relieve pressure

Question 13

what muscle is involved in opening eyes wider reflex

Answer 13

elevation of the eyelid by levator palpebrae superioris (contains skeletal and posterior slip of smooth muscle)

Question 14

which division of the NS innervates pupillary constriction?

Answer 14

parasympathetic

Question 15

example of a syndrome that causes a miotic pupil (constriction)

Answer 15

Horner’s syndrome

Question 16

what does a fixed pinpoint pupil indicate?

Answer 16

pathological sign (opiate drugs)
pontine issue

Question 17

which muscle controls pupillary constriction?

Answer 17

sphincter pupillae encircles the internal circumference of the iris

Question 18

what is a fixed/blown pupil a sign of?

Answer 18

CNIII pathology (cannot constrict)

Question 19

which division of the autonomic nervous system causes pupillary dilation?

Answer 19

sympathetic

Question 20

causes of a dilated pupil

Answer 20

see distant objects
sick patient e.g. fight/flight response
mydiatric drugs

Question 21

which muscle dilates the pupil?

Answer 21

dilator pupillae which is arranged radially from external circumference of the iris

Question 22

what is the pupillary light reflex

Answer 22

constriction of the pupil due to shining of light into the eye

Question 23

afferent (special sensory) role in pupillary light reflex

Answer 23

ipsilateral CNII (right eye, right optic nerve)

Question 24

CNS connection in midbrain in pupillary light reflex

Answer 24

connection in midbrain (PTN > EWN > ciliary ganglion > ciliary nerve)

Question 25

efferent (motor) role in pupillary light reflex

Answer 25

bilateral via CNIII (direct and consensual response)

Question 26

role of the lens accommodation reflex

Answer 26

allows eyes to focus on close and distant objects

Question 27

which structures are involved in the lens accommodation reflex?

Answer 27

suspensory ligaments
lens
ciliary body (muscle)

Question 28

lens accommodation reflex for distant objects?

Answer 28

ciliary muscle relaxes in far vision causing ligaments to tighten and the lens flattens (sympathetic)

Question 29

lens accommodation reflex for near objects

Answer 29

ciliary muscle contracts so the ligaments relax causing the lens to adopt a spherical shape (parasympathetic)

Question 30

what CN does the lens accommodation reflex test?

Answer 30

CNIII

Question 31

three divisions of lacrimation

Answer 31

1. basal tears
2. reflex tears
3. emotional tears

Question 32

describe basal tears

Answer 32

these are produced all the time to clean cornea, nourish and hydrate avascular structures

Question 33

describe reflex tears

Answer 33

extra tears produced in response to mechanical or chemical stimuli

Question 34

afferent of reflex tears

Answer 34

CNV1

Question 35

efferent of reflex tears

Answer 35

CNVII