Anatomy Tutorial

Question 1

what are the 3 functions of the eyelids?

Answer 1

produce lipid components of tears
wash tears over the eye
close/protect the eye

Question 2

palsy of which nerve can cause horner’s syndrome, droopy eyelid and fixed constricted pupil?

Answer 2

CN III (oculomotor)

Question 3

what 2 muscles open the eye?

Answer 3

levator palpebrae superioris (LPS)

muller’s muscle (few sympathetic fibres within LPS which maintain tone and keep the eye open)

Question 4

what nerve innervates the LPS muscle?

Answer 4

CN III (oculomotor)

Question 5

what muscle closes the eye?

Answer 5

orbicularis oculi

Question 6

what nerve innervates orbicularis oculi?

Answer 6

facial nerve

Question 7

palsy of which nerve can result in the inability to close the eye and what is this known as?

Answer 7

CN VII (facial)
bells palsy

Question 8

what are the 2 functions of the orbicularis oculi?

Answer 8

reflex blink (passive)
active blinking/closing of eyes

Question 9

what is the function of the cornea?

Answer 9

refract light

- main refractor of light

Question 10

what is a cataract?

Answer 10

cloudy lens

- sort of umbrella term, many causes

Question 11

what is the accommodation reflex and what 3 changes occur in the eye during this reflex?

Answer 11

changing from close up to far distance vision
pupils constrict
lens changes shape
eyes converge

Question 12

how does the lens change in the accommodation reflex?

Answer 12

long distance vision
- ciliary muscle relaxes and suspensory ligaments tighten, pulling the lens flat
close range vision
- ciliary muscle constricts, loosening the suspensory ligaments, allowing the lens to spring back to spherical shape

Question 13

is constriction of the eye is under sympathetic or parasympathetic control?

Answer 13

parasympathetic

Question 14

give a characteristic feature of all autonomic parasympathetic supply ganglions?

Answer 14

any autonomic parasympathetic supply has a ganglion near the target organ

Question 15

what does RAPD stand for?

Answer 15

relative afferent pupillary defect

Question 16

what nerve does RAPD test?

Answer 16

optic

Question 17

how is RAPD tested?

Answer 17

shine light in one eye (therefore flooding midbrain with light)
wait for both eyes to constrict (direct and consensual reflex)
quickly jump to the other eye and shine the light in the other eye without giving the pupils a chance to re-dilate
normal response = both pupils will stay as a pin-point
RAPD response = pupils will grow in size (can be very subtle) as optic nerve is not working 100% so pupil cant constrict to full capacity and therefore consensual reflex will also be affected

Question 18

how do signals from the upper retina travel in the optic pathway?

Answer 18

signals from upper retina stay in the upper aspect of the optic nerve through the chiasm until it reaches the nucleus
signal then makes a straight B line to the occipital cortex in the parietal lobe

Question 19

how do signals from the lower retina travel in the optic pathway?

Answer 19

signals from the lower retina travel in the lower aspect of the optic nerve until they reach the nucleus
the signal then needs to loop around the ventricles via the temporal lobe (as the ventricles obstruct the pathway) to reach the occipital cortex

Question 20

the upper retina detects light from what part of the visual field?

Answer 20

lower visual field

Question 21

the lower retina detects light from what part of the visual field?

Answer 21

upper visual field