Eye Movements of the Visual System Flashcards
How many muscles innervate the eye?
6
What nerves innervate the eye muscles?
CN III (oculomotor) CN IV (trochlear) CN VI (abducens)
Define duction
Eye movement in one eye
Define version
Simultaneous movement of both eyes in the same direction
Define vergence
Simultaneous movement of both eyes in the opposite direction to version
Define convergence
Simultaneous adduction of both eyes when viewing a near object
Define saccades
Short, fast bursts of movement
What are the different types of saccades and what do they mean?
Reflexive saccade (to external stimuli)
Scanning saccade
Predictive saccade (to track objects)
Memory guided saccade
Define smooth persuit
Sustained slow movements of the eye
Where does the superior oblique move the eye?
Down and out
Where does the inferior oblique move the eye?
Up and out
What nerves innervate which of the 6 eye muscles
Oculomotor innervates all of them (including levator palpabrae superioris) apart from
LR6SO4
Lateral rectus is innervated by CN VI (abducens)
Superior oblique is innervated by CN IV (trochelar)
What muscle does abduction test?
Lateral rectus
What muscle does adduction test?
Medial rectus
What muscle does elevation and abduction test?
Superior rectus
What muscle does elevation and adduction test?
Inferior oblique
What muscle does depression and abduction test?
Inferior rectus
What muscle does depression and adduction test?
Superior oblique
What do the suffixes duction and version indicate in terms of movements of the ye
duction= one eye version= both eyes
What are the prefixes in terms of eye movement for elevation, depression, right and left?
Elevation= supra Depression= infra Right= dextro Left= levo
Define torsion as an eye movement
Rotation of eye around the anterior posterior axis of the eye
How does the affected eye appear in third nerve palsy- explain why
The eye goes down and out (the lateral rectus and superior oblique are unaffected as they aren’t innervated by CN III) and the eyelid is droopy (the levator palpabrae superioris isnt working)
How does the affected eye appear in sixth nerve palsy- explain why
Affected eye cannot abduct because the lateral rectus isnt working so it deviated inwards
When does double vision occur in sixth nerve palsy?
When gazing to the side of the affected eye
When is the optokinetic nystagmus reflex used and what does it indicate?
It is used to check that there is normal visual acuity in children who can’t speak yet
