Visual system : Eye movements Flashcards
What is Duction?
Eye movement in one eye
What is Version?
Simultaneous movement of both eyes in the same direction
What is Vergence?
Simultaneous movements of both eyes in opposite direction
What is convergence?
Simultaneous adduction movement in both eyes when viewing a near object
What is version when it is to the left?
To the right?
Left = Levoversion Right = Dextoversion
What is Saccade?
Short fast burst of eye movement: (900/s)
can have multiple types e.g.
- reflexive saccade to external stimuli
- Scanning saccade
- predictive saccade to track objects
- memory guides saccade
What is smooth pursuit?
Sustained slow eye movement
driven by motion of a moving target across the retina (60/s)
What four straight muscles are there?
Superior rectus
Inferior rectus
Lateral rectus
Medial rectus
Where to all the eyes muscles except the inferior oblique come in from?
Out of a cone from the back of the orbit
- Inferior oblique comes in nasally
What does the superior rectus do?
Moves eye up
attached at 12 oclock
What does the lateral rectus do?
Attaches on the temporal side of the eye
Moves the eye toward the outside of the head (towards temple)
What does the medial Rectus do?
Attaches to the nasal side of the eye
Moves the eye toward the middle of the head
What does the superior oblique do?
Attached high on the temporal side of the eye
Passed under the superior rectus
Moves eye in a diagonal pattern down and out
Travels through the trochlea
What does the inferior oblique do?
Attached low on the nasal side of the eye
Passed over the inferior rectus
Moves eye in a diagonal patter = up and out
What muscles does the superior branch of the oculomotor nerve innervate?
Superior branch:
- Superior rectus
- Levator palpebrae superioris
What muscles does the inferior branch of the oculomotor nerve innervate?
- Inferior rectus
- medial rectus
- inferior oblique
- parasympathetic nerve that constricts pupil
What does the trochlear nerve innervate?
Superior oblique
What does the abducens nerve innervate?
Lateral rectus
How do we test the lateral rectus?
Abducted position
How do we test the medial rectus?
Adducted position
How do we test superior rectus?
Elevated and abducted position
How do we test for the inferior rectus
depressed and abducted position
How do we test for inferior oblique?
Elevated and adducted position
How do we test for the superior oblique?
Depressed and adducted position
What does third nerve palsy look like?
Affected eye is down and out
What causes third nerve palsy (describe innervation)
(oculomotor not working) Droopy eyelid - loss of elevator palpebrae
Unopposed superior oblique = so look down
Unopposed lateral rectus action = out
What does sixth nerve palsy look like? (abducens)
Affected eye unable to abduct and deviates inwards.
More apparent when px asked to abduct the affected eye
What makes 6th nerve palsy double vision worse?
gazing to the side of affected eye
What is Nystagmus?
Oscillatory eye movement
What is Optokinetic nystagmus
Smooth pursuit + fast phase reset saccade
What is the optokinetic nystagmus reflex?
in testing visual acuity in pre-verbal children by observing the presence of nystagmus movement in response to moving grating patterns of various spatial frequencies
- watch video : the eye ‘flickers’ when watching changing symbols
