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84 Cards in this Set
- Front
- Back
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Define ductions
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movements of one eye
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define versions
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movements of both eyes in the same direction
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define vergences
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movements of both eyes in opposite directions
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Define: abduction, adduction, supraduction, infraduction, incyclotorsion/intorsion, excyclotorsion/extorsion
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Away from the nose (abduction)
Toward the nose (adduction) Upward (elevation or supraduction) Downward (depression or infraduction) Top of the eye rotates toward the nose (incyclotorsion) Top of the eye rotates away from the nose (excyclotorsion) |
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Define: dextroversion, levoversion, supraversion, infraversion, dextrocycloversion, levocycloversion
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To the right (dextroversion)
To the left (levoversion) Upward (elevation or supraversion) Downward (depression or infraversion) Top of eyes moves to the right (dextrocycloversion) Top of eyes moves to the left (levocycloversion) |
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Define: convergence, divergence, incyclovergence, excyclovergence, positive vertical vergence, negative vertical vergence
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Both eyes to nose (convergence)
Both eyes move away from the nose (divergence) Both eyes rotate toward the nose (incyclovergence) Both eyes rotate away from the nose (excyclovergence) Right eye elevated and left eye depressed (positive vertical vergence) Left eye elevated and right eye depressed (negative vertical vergence) |
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Define the X axis of the eye
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Goes through center of pupil
clockwise and counterclockwise eye movements (torsions) |
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Define the Y axis of the eye
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Crosses through the nasal and temporal poles of eye
Vertical eye movement Rotation=elevation or depression |
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Define the Z axis of the eye
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Crosses through the superior and inferior poles of the eye
Horizontal eye movement Rotation = adduction or abduction |
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What EOM(s) are innervated by the Occulomotor nerve (CN3)?
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inferior oblique
inferior rectus medial rectus superior rectus |
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What EOM(s) are innervated by the Trochlear nerve (CN 4)?
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superior oblique
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What EOM(s) are innervated by the Abducens nerve (CN 6)?
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lateral rectus
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What EOM is most inferior in the orbit?
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inferior oblique
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Where is the nucleus of the Inferior Oblique
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Ipsilateral oculomotor complex
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Where is the origin of the inferior oblique?
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anterior to equator on maxilla
-the only EOM not originating from the annulus of zinn |
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What movement of the inferior oblique is isolated by abduction of 39 degrees?
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excyclotorsion
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What movement of the inferior oblique is isolated by adduction of 51 degrees?
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elevation
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Where is the insertion of the inferior oblique?
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posterior to equator
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Which EOM is most susceptible in a blow out fracture?
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Inferior rectus
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Where is the nucleus of the inferior rectus?
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ipsilateral oculomotor complex
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Where is the origin of the inferior rectus?
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annulus of Zinn
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Where is the insertion of the inferior rectus?
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6.8mm from limbus
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What movement of the inferior rectus is isolated by abduction of 23 degrees?
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depression
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What movement of the inferior rectus is isolated by adduction of 67 degrees?
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excyclotorsion
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Which EOM as the most anterior insertion?
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Medial Rectus
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Where is the nucleus of the medial rectus?
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ipsilateral oculomotor complex
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Where is the origin of the medial rectus?
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medial annulus of Zinn
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Where is the insertion of the medial rectus?
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5.3mm from limbus
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What is the most superior muscle in the orbit?
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superior rectus
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where is the nucleus of the superior rectus?
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contralateral oculomotor complex
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where is the origin of the superior rectus?
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superior annulus of Zinn
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where is the insertion of the superior rectus?
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7.9mm from limbus
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What movement of the superior rectus is isolated by abduction of 23 degrees?
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elevation
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What movement of superior rectus is isolated by adduction of 67 degrees?
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incyclotorsion
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Which EOM is most susceptible to trauma?
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superior oblique
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Where is the nucleus of the superior oblique?
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contralateral trochlear nucleus
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Where is the origin of the superior oblique?
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superior medial annulus of Zinn
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Where are the anatomical and functional insertions of the superior oblique?
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anatomical --> posterior to equator
functional--> trochlea (anterior to equator) |
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What movement of the superior oblique is isolated by abduction of 36 degrees?
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incyclotorsion
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What movement of the superior oblique is isolated by adduction of 54 degrees?
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depression
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Which EOM is most susceptible to increased intracranial pressure?
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lateral rectus
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where is the nucleus of the lateral rectus?
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ipsilateral abducens nucleus
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where is the origin of the lateral rectus?
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lateral annulus of Zinn
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Where is the insertion of the lateral rectus?
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6.9mm from limbus
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In what order, from anterior to posterior, do the rectus EOMs insert?
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medial rectus: 5.5mm
inferior rectus: 6.5mm lateral rectus: 6.9mm superior rectus: 7.7mm (goes clockwise starting w/ MR) |
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Define primary, secondary, and tertiary positions?
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Primary: eyes looking straight ahead
-deviation with strabismus/tropia Secondary: eye rotation on only one axis -looking purely up, down, left, right Tertiary: eye rotation on two axes -looking up and right, down and left, etc. |
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Do primary, secondary, and tertiary actions of EOMs correlate to primary, secondary, and tertiary ocular positions?
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!NO!
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Define agonist, antagonist, and yoked EOMs.
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agonist: aids same eye movement (synergist)
antagonist: performs opposite eye movement yoked: muscle of opposite eye that does same eye movement |
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What is Herring's law of equal innervation?
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Yoked muscles receive same innervation
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What is Sherrington's law of reciprocal innervation?
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antagonist muscles of same eye must relax when the agonist muscle contracts
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What do superior EOMs have in common?
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contralateral nuclei, Intortion
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What do inferior muscles have in common?
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Extortion
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What do superior and inferior rectus EOMs have in common?
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adduct
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What do obliques have in common?
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abduct
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What are the types of eye movements?
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Gaze directing and Gaze holding
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What are the 3 methods of gaze directing?
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Saccades, smooth pursuits, vergences
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What are the 3 methods of gaze holding?
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fixation, optokinetic, vestibular
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What are saccades?
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quick eye movements in response to sudden or novel stimuli
-doesn't require a target. -can be used to track a quickly moving target |
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What are smooth pursuits?
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slow eye movement that require a target
-can't track quickly moving targets -used to keep a target on the fovea |
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What are vergences as part of gaze directing?
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slower eye movements to track objects moving toward or away
-like smooth pursuits -eyes move in opposite directions |
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What is fixation?
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small eye movements required to keep image on the fovea of a stationary object when the head is immobile
-purkinje tree |
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What are the 3 main types of fixation?
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-microsaccades
-microtremors -microdrifts |
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What is the Optokinetic Response?
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holds image steady on the retina during sustained head movements
-induces nystagmus -requires target -can estimate acuity -can detect malingers |
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What are vestibular eye movements?
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eye movements in resopnse to a brief change in head position
-eyes move opposite head -keeps target on fovea -doesn't require a target |
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Define comittant and non-commitant tropias.
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commitant: deviation the same in all gazes
non-commitant: deviation varies significantly w/ change in eye position |
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Define phoria and tropia.
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Phoria: latent misalignment of the eye when viewing one eye (not fused)
Tropia: manifest misalignment of the eye when viewing both eyes (fused) |
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What ways can we measure eye movements?
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photography, electroculography, magnetic search coil, infrared limbal recording
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Tidbits on photography?
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Static and dynamic ocular defects
-Static: strabismus (ocular reflex) -Dynamic: nystagmus (video recording) Less expensive recordings can be used in office and for education More expensive recordings are used in research |
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Tidbits on electrooculography.
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Uses electrodes to determine eye position
-Based on metabolism differences in eye Can detect movements to 70 degrees Easy to set up Minimal patient discomfort Susceptible to facial expression and blink |
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Tidbits on Magnetic Search Coil.
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Uses contact lens-like device on eye to monitor eye movements
Can detect eye movements as small as one arc minute and changes up to 30 degrees Uncomfortable for patient after several minutes Mainly used in large research laboratories |
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Tidbits on Infrared Limbal Recording.
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Detects eye movements by noting the difference in brightness of cornea and iris to white sclera
Can detect eye movements as small as 0.25 degrees and up to 7.5 degrees Used in optometric offices The Visagraph is a common example |
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What are the cardinal positions of gaze?
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left, right, up and right, down and right, up and left, down and left
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What are the 2 main layers of EOM fibers?
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Orbital: adjacent to periorbita and orbital bone
Global: adjacent to the eye and optic nerve |
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What are the 2 sublayers of the Orbital EOM fiber layer?
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Periorbita
Orbital bone up to the tendon |
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What are the 3 sublayers of the global layer of EOM fiber layers?
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eye
optic nerve full muscle length |
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What are the two types of innervation for EOM muscle fibers?
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Singly Innervated Fibers (SIFs)
-Fast ATPase -Capable of anaerobic activity -Twitch capacity at the full length of fiber Multiply Innervated Fibers (MIFs) -Slower ATPase activity -Non-twitch at ends -twitch at centers |
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Define Red, Intermediate, and Pale/White SIFs
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Red: highest fatigue resistance
Intermediate: intermediate fatigue resistance Pale/White: lowest fatigue resistance -all are fast twitch singly innervated fibers |
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What is the breakup of fibers in the orbital and global layers?
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Orbital layer
-80% SIFs -20% MIFs Global layer -33% red SIFs -32% white SIFs -25% intermediate SIFs -10% MIFs |
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What are the ipsilatera and contralateral agonist and antagonist for R Lateral Rectus
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Ipsilateral Agonist: none
Ipsilateral Antagonist: R-MR Contralateral Agonist: L-MR Contralateral Antagonist: L-LR |
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What are the ipsilatera and contralateral agonist and antagonist for R Medial Rectus
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Ipsilateral Agonist: none
Ipsilateral Antagonist: R-LR Contralateral Agonist: L-LR Contralateral Antagonist: L-MR |
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What are the ipsilatera and contralateral agonist and antagonist for R Inferior Rectus
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Ipsilateral Agonist: R-SO
Ipsilateral Antagonist: R-SR Contralateral Agonist: L-SO Contralateral Antagonist: L-IO |
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What are the ipsilatera and contralateral agonist and antagonist for R Superior Rectus
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Ipsilateral Agonist: R-IO
Ipsilateral Antagonist: R-IR Contralateral Agonist: L-IO Contralateral Antagonist: L-SO |
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What are the ipsilatera and contralateral agonist and antagonist for R Inferior Oblique
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Ipsilateral Agonist: R-SR
Ipsilateral Antagonist: R-SO Contralateral Agonist: L-SR Contralateral Antagonist: L-IR |
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What are the ipsilatera and contralateral agonist and antagonist for R Superior Oblique
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Ipsilateral Agonist: R-IR
Ipsilateral Antagonist: R-IO Contralateral Agonist: L-IR Contralateral Antagonist: L-SR |
