11 Questions
What are the recti muscles involved in eye movement?
Superior rectus, Inferior rectus, Lateral rectus, Medial rectus
Name the oblique muscles involved in eye movement.
Superior oblique, Inferior oblique
Which cranial nerve innervates the Superior Rectus, Inferior Rectus, Medial Rectus, and Inferior Oblique muscles?
Oculomotor nerve (CN III)
EOM stands for Extraocular __________.
muscles
Agonist muscles move the eye in the same direction as the synergist muscles.
False
Match the following eye movement terminology with their definitions:
Vergence = Disjunctive eye movement in opposite directions Version = Synchronous movement of both eyes in the same direction Duction = Monocular movement of the eye Torsion = Rotational eye movement
What are the four recti muscles involved in eye movement?
Superior rectus, Inferior rectus, Lateral rectus, Medial rectus
Name the two oblique muscles involved in eye movement.
Superior oblique, Inferior oblique
Which cranial nerve innervates the Lateral Rectus muscle?
Abducent nerve (CN VI)
Excyclotorsion is an outward, torsional movement of the eye.
True
_____ is a disjunctive movement where both eyes move inwards.
Convergence
Study Notes
Muscles Involved in Eye Movement
- Recti muscles:
- Superior rectus
- Inferior rectus
- Lateral rectus
- Medial rectus
- Oblique muscles:
- Superior oblique
- Inferior oblique
Attachment of the EOM
- Insertion and origins of EOM:
- Medial rectus: annulus of Zinn, eye anterior medial surface
- Lateral rectus: annulus of Zinn, eye anterior lateral surface
- Superior rectus: annulus of Zinn, eye anterior superior surface
- Inferior rectus: annulus of Zinn, eye anterior inferior surface
- Superior oblique: sphenoid bone through the trochlear, eye posterior superior lateral surface
- Inferior oblique: maxillary bone, eye posterior inferior lateral surface
EOM and Their Innervations
- Nerve and corresponding EOM:
- Oculomotor nerve (CNIII): SR, IR, MR, IO
- Trochlear nerve (CNIV): SO
- Abducent nerve (CNVI): LR
Actions and Cranial Nerve Innervation of EOM
- Primary, secondary, and tertiary actions of the EOM:
- Medial rectus: adduction
- Lateral rectus: abduction
- Superior rectus: elevation, incyclotorsion, adduction
- Inferior rectus: depression, excyclotorsion, adduction
- Superior oblique: incyclotorsion, depression, abduction
- Inferior oblique: excyclotorsion, elevation, abduction
Agonist and Synergist Muscles
- Agonist: primary muscle that moves an eye in a given direction
- Synergist: muscle in the same eye that moves the eye in the same direction as the agonist
Antagonist Muscles
- Antagonist: muscle in the same eye that moves the eye in the opposite direction of the agonist
Yoke Muscles
- Yoke muscles: primary muscles in each eye that accomplish a given movement of the two eyes in the same direction
- Example for right gaze: RLR and LMR
- Yoked pairs of EOM muscles:
- RLR and LMR
- MR and LR
- SR and IO
- IR and SO
- SO and IR
- IO and SR
Herring's Law of Reciprocal Innervation
- Law states that when an agonist contracts during movement of an eye, there is a simultaneous and equal relaxation of its antagonist fellow muscle
Hering's Laws of Equal Innervation
- Corresponding or yoked muscles of each eye are equally innervated
- Law is specified with respect to static eye position changes for example in conjugate movement
Eye Movement
- Duction: movement of one eye
- Types of duction:
- Adduction: inward movement of the eye or towards the nose (nasal movement) or medially
- Abduction: outward movement of the eye or towards the ear (temporal movement) or laterally
- Supraduction (sursumduction)
- Infraduction (deorsumduction)
- Torsion: rotation around the line of sight (Y-axis)
- Types of torsion:
- Incyclotorsion (intorsion): inward, torsional (rotational) movement of the eye
- Excyclotorsion (extorsion): outward, torsional (rotational) movement of the eye
- Version: eye movement involving both eyes moving synchronously and symmetrically in the same direction
- Dextroversion / right gaze
- Laevoversion / left gaze
- Sursumversion / elevation / up gaze
- Deorsumversion / depression / down gaze
- Dextroelevation / gaze up and right
- Dextrodepression / gaze down and right
- Laevoelevation / gaze up and left
- Laevodepression / gaze down and left
- Dextrocycloversion – top of the eye rotates to the right
- Laevocycloversion – top of the eye rotates to the left
Other Types of Eye Movement
- Fixational: eye movement associated with an effort to keep the eye completely still
- Saccadic: fast or rapid eye movement, looking at the ability to shift a point of visual fixation
- Pursuit: smooth following of a moving object
- Optokinetic: eye movement evoked by following a moving target
- Vestibular: eye movement in response to head acceleration
Muscles Involved in Eye Movement
- Recti muscles:
- Superior rectus
- Inferior rectus
- Lateral rectus
- Medial rectus
- Oblique muscles:
- Superior oblique
- Inferior oblique
Attachment of the EOM
- Insertion and origins of EOM:
- Medial rectus: annulus of Zinn, eye anterior medial surface
- Lateral rectus: annulus of Zinn, eye anterior lateral surface
- Superior rectus: annulus of Zinn, eye anterior superior surface
- Inferior rectus: annulus of Zinn, eye anterior inferior surface
- Superior oblique: sphenoid bone through the trochlear, eye posterior superior lateral surface
- Inferior oblique: maxillary bone, eye posterior inferior lateral surface
EOM and Their Innervations
- Nerve and corresponding EOM:
- Oculomotor nerve (CNIII): SR, IR, MR, IO
- Trochlear nerve (CNIV): SO
- Abducent nerve (CNVI): LR
Actions and Cranial Nerve Innervation of EOM
- Primary, secondary, and tertiary actions of the EOM:
- Medial rectus: adduction
- Lateral rectus: abduction
- Superior rectus: elevation, incyclotorsion, adduction
- Inferior rectus: depression, excyclotorsion, adduction
- Superior oblique: incyclotorsion, depression, abduction
- Inferior oblique: excyclotorsion, elevation, abduction
Agonist and Synergist Muscles
- Agonist: primary muscle that moves an eye in a given direction
- Synergist: muscle in the same eye that moves the eye in the same direction as the agonist
Antagonist Muscles
- Antagonist: muscle in the same eye that moves the eye in the opposite direction of the agonist
Yoke Muscles
- Yoke muscles: primary muscles in each eye that accomplish a given movement of the two eyes in the same direction
- Example for right gaze: RLR and LMR
- Yoked pairs of EOM muscles:
- RLR and LMR
- MR and LR
- SR and IO
- IR and SO
- SO and IR
- IO and SR
Herring's Law of Reciprocal Innervation
- Law states that when an agonist contracts during movement of an eye, there is a simultaneous and equal relaxation of its antagonist fellow muscle
Hering's Laws of Equal Innervation
- Corresponding or yoked muscles of each eye are equally innervated
- Law is specified with respect to static eye position changes for example in conjugate movement
Eye Movement
- Duction: movement of one eye
- Types of duction:
- Adduction: inward movement of the eye or towards the nose (nasal movement) or medially
- Abduction: outward movement of the eye or towards the ear (temporal movement) or laterally
- Supraduction (sursumduction)
- Infraduction (deorsumduction)
- Torsion: rotation around the line of sight (Y-axis)
- Types of torsion:
- Incyclotorsion (intorsion): inward, torsional (rotational) movement of the eye
- Excyclotorsion (extorsion): outward, torsional (rotational) movement of the eye
- Version: eye movement involving both eyes moving synchronously and symmetrically in the same direction
- Dextroversion / right gaze
- Laevoversion / left gaze
- Sursumversion / elevation / up gaze
- Deorsumversion / depression / down gaze
- Dextroelevation / gaze up and right
- Dextrodepression / gaze down and right
- Laevoelevation / gaze up and left
- Laevodepression / gaze down and left
- Dextrocycloversion – top of the eye rotates to the right
- Laevocycloversion – top of the eye rotates to the left
Other Types of Eye Movement
- Fixational: eye movement associated with an effort to keep the eye completely still
- Saccadic: fast or rapid eye movement, looking at the ability to shift a point of visual fixation
- Pursuit: smooth following of a moving object
- Optokinetic: eye movement evoked by following a moving target
- Vestibular: eye movement in response to head acceleration
This quiz covers the different muscles involved in eye movement, including recti and oblique muscles, and their attachments and origins.
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