reflexes of the eye

Question 1

what does the opthalmic nerve innervate in the face

Answer 1

• upper eyelid
• cornea
• conjunctiva

Question 2

what does the maxillary nerve innervate in the face

Answer 2

• skin of the lower eyelid

- skin over the maxilla

Question 3

what does the mandibular nerve innervate in the face

Answer 3

• skin over mandible and TMJ

- except angle of mandible

Question 4

what are the autonomic reflexes of the eye

Answer 4

• wide eye opening of flight or fight
• pupillary light reflex
• accommodation reflex
• lacrimation reflex

Question 5

what does the vestibulo-ocular reflex do

Answer 5

turns eyes in the opposite direction to a head movement

-stabilises gaze on an object during head movement

Question 6

what is the oculocardiac reflex

Answer 6

reflex bradycardia in response to tension on extraocular muscles or pressure on eye

Question 7

what are the sympathetic reflexes of the eye

Answer 7

• get more light into eyes
• open eyes wider
• focus on far objects
• emotional lacrimation

Question 8

parasympathetic reflexes of the eye

Answer 8

• get less light into eyes
• focus on near objects
• reflex lacrimation (to wash away the stimulant foreign body and clean the cornea)

Question 9

which muscle opens the eyes wider

Answer 9

levator palpebrae superioris

Question 10

how does the pupil constrict

Answer 10

• parasympathetics constrict the pupil

- sphincter pupillae fibres encircle pupil

Question 11

when does the pupil constrict

Answer 11

in bright light and rest&digest

Question 12

how does the pupil dilate

Answer 12

• sympathetic innervation dilates the pupil

- dilator pupillae fibres are radially arranged

Question 13

what is a non-physiologically enlarged pupil called

Answer 13

a mydriatic pupil

Question 14

what is a non-physiologically constricted pupil called

Answer 14

miotic pupil

-horners syndrome for example

Question 15

how many neurons are in the chain for the pupillary light reflex

Answer 15

4

Question 16

what do the first neurons do in the pupillary light reflex

Answer 16

• retinal ganglion cells
• pass via ipsilateral optic nerve
• decussate in optic chiasm
• synapse in pretectal nucleus in midbrain

Question 17

what do the second neurons do in the pupillary light reflex

Answer 17

-locates entirely within midbrain and connect pretectal nucleus to next synapse in Edinger-Westphal nucleus

Question 18

what do the third neurons do in the pupillary light reflex

Answer 18

pass from EW nucleus, via CN III then its inferior division, to synapse in ciliary ganglion

Question 19

what do the fourth neurons do in pupillary light reflex

Answer 19

course in short ciliary nerves to sphincter pupillae muscles

Question 20

what does the ciliary muscle do in far vision

Answer 20

relaxes

-ligament tightens and lens flattens to focus on an object in the distance

Question 21

what does the ciliary muscle do in near vision

Answer 21

contracts

-ligament relaxes and lens becomes spherical to focus on near objects

Question 22

what is the lens accommodation reflex

Answer 22

focusing on near objects

Question 23

function of basal tears

Answer 23

• corneal health
• clean/nourish and hydrate the avascular cornea
• contain lysozyme (hydrolyses bacterial cell walls)

Question 24

what are reflex tears

Answer 24

extra tears in response to mechanical or chemical stimulation