Eye Movements Flashcards
Why do we have binocular vision?
Wider field of vision,
Depth perception,
Element of redundancy (though not really).
what does misalignment of visual axes cause?
Diplopia (double vision?)
where do the 6 muscles that move the eyeball insert?
The sclera
Where do the extra ocular muscles originate from?
Apex of the orbit, apart from inferior oblique which arises from the floor of the orbital cavity anteriorly.
What is the common origin of the 4 recti?
Common tendinous ring
What does the pneumonic LR6SO4 signify?
Lateral rectus is supplied by cranial nerve VI,
Superior oblique is supplied by cranial nerve IV.
Why do some muscles end up attaching to the eye at an oblique angle?
Extraocular muscles run in line with the axis of the orbit, which runs at an oblique angle to the visual axis of the eye.
How is primary resting gaze maintained?
Antagonism of muscles provides equal and opposite pull. Without this, deviation occurs.
What movements is the eye capable of?
Elevation, depression, abduction, adduction, intorsion, extorsion.
What movement is caused by the medial rectus?
What about the lateral rectus?
Adduction.
Abduction.
What movements are completed by the superior rectus?
Elevation (most powerful when eyes are lateral) slight adduction, slight intorsion.
Where does the superior rectus originate?
How does it insert?
Arises from the apex of the orbit.
Inserts obliquely into superior anterolateral surface of the globe.
What actions is the inferior rectus responsible for?
Depression (stronger if eyes lateral), adduction, extorsion.
Where does the inferior rectus muscle originate?
How does it insert?
Originates at the apex of the orbit.
Inserts obliquely into anteroinferior surface of the globe.
What movements is the superior oblique responsible for?
Intorsion, depression (stronger when eye medial), slight abduction
Where does the superior oblique originate?
Where does it insert?
Originates from apex of orbit, passes through Trochlea (functional origin) and inserts into superior-posterior aspect of the globe
What actions is the inferior oblique responsible for?
Extortion, elevation (more powerful when eye medial), slight abduction.
Where does the inferior oblique arise from?
Where does it insert?
Arises from anteromedial surface of the floor of the orbit. Inserts into the inferno-posterior aspect of the globe.
Which muscles are stronger elevators and depressors when the eye is moved laterally (abducted)?
Superior and inferior recti
Which muscles are stronger elevators and depressors when the eye is moved medially (adducted)?
Superior and inferior obliques
How are eye movements tested?
Making a ‘gearbox’ shape with finger and ask them to follow the pattern with their eyes. This tests elevation and depression in both lateral and medial eye positions.
What is strabismus?
Ocular misalignment. Common in children, acquired in adults due to factors such as compression of nerves innervation muscles of the eye or vasculopathic damage.
Are vasculopathic lesions pupil sparing or pupil involving?
What about compressive lesions?
Pupil sparing.
Pupil involving.
What is the most likely cause of CN III, IV and VI lesions?
Vasculopathic. These usually self resolve within a few months.
What indicates possible malignant cause of CN III, IV or VI lesions?
Headache, pupil involvement
