Eye Movements Flashcards
What is duction, version, vergence and convergence?
Duction – Eye Movement in One Eye
Version – Simultaneous movement of both eyes in the same direction (dextroversion to right, levoversion left)
Vergence – Simultaneous movement of both eyes in the opposite direction
Convergence – Simultaneous adduction (inward) movement in both eyes when viewing a near object
What is a saccade?
Saccade refers to short fast burst eye movement, up to 900 degrees per second. Types: Reflexive saccade to external stimuli Scanning saccade Predictive saccade to track objects Memory-guided saccade
What is smooth pursuit?
Smooth Pursuit is a slow sustain movement, up to 60 degrees per second. It is an involuntary movement, driven by a moving target.
Name the extraocular muscles
Four straight muscles: Superior rectus, Inferior rectus, Medial rectus, Lateral Rectus
Inferior and Superior oblique
5 out of 6 muscles come out of a cone from the back of the orbit. Inferior oblique comes in nasally.
What is the role of the vertical rectus muscles?
Vertical Rectus muscles attach anterior to the globe equator, and pull backwards and nasally. Superior attaches at 12:00 position and pulls up. Inferior is opposite. When eye is adducted, produce torsion motion. When eye abducted, produce maximum up and down motion.
What is the role of lateral and medial rectus?
Lateral attaches on the temporal side of the eye. Moves the eye toward the outside of the head (toward the temple). Medial attaches on the nasal side of the eye and moves eye inwards.
What is the role of the superior oblique?
Attached high on the temporal side of the eye.
Passes under the Superior Rectus.
Moves the eye in a diagonal pattern down and out
Travels through the trochlea
What is the role of the inferior oblique?
Attached low on the nasal side of the eye.
Passes over the Inferior Rectus.
Moves the eye in a diagonal pattern - up and out.
What muscles are innervated by the oculomotor nerve?
Superior Branch innervates:
Superior Rectus – elevates eye
levator palpebrae superioris - raises eyelid
Inferior Branch innervates: Inferior Rectus – depresses eye Medial Rectus – adducts eye Inferior Oblique – elevates eye Parasympathetic Nerve – constricts pupil
What muscle does the trochlear nerve innervate?
Superior Oblique – depresses eye
What muscle does the abducens nerve innervate?
Lateral Rectus – abducts eye
How is eye movement tested?
Abduction – Lateral Rectus Adduction – Medial Rectus Elevated and Abducted – Superior Rectus Depressed and Abducted – Inferior Rectus Elevated and Adducted – Inferior Oblique Depressed and Adducted – Superior Oblique
How are eye movements defined?
Elevation: Supraduction – one eye Supraversion – both eyes Depression: Infraduction – one eye Infraversion – both eyes Dextroversion: Right Abduction Left Adduction Opposite for levoversion Torsion - rotation of eye around the anterior-posterior axis of the eye
What are the signs of 3rd nerve palsy?
When there is a complete third nerve palsy, only muscles not innervated by the third cranial nerve in the affected eye are working. Only lateral rectus muscle and superior oblique working (abduction and depression). Hence eye adopts down and out position. Accompanied by ptosis as levator palpebrae superioris not working.
What are the signs of 6th nerve palsy?
Affected eye unable to abduct and deviates inwards as lateral rectus affected. Double vision worsen on gazing to the side of the affected eye.
