Eye Movements and Ocular Motility Flashcards
(26 cards)
What are the two main types of eye movements?
Monocular Eye Movements (Ductions): Movements of one eye.
Binocular Eye Movements (Version and Vergence): Movements of both eyes.
: What are the types of monocular eye movements?
Adduction: Movement of the eye toward the nose.
Abduction: Movement of the eye toward the ear.
Supraduction (Elevation): Movement of the eye upward.
Infraduction (Depression): Movement of the eye downward.
Excylocycloduction (Extorsion): Rotation of the eye outward.
Incycloduction (Intorsion): Rotation of the eye inward.
What are the binocular eye movements?
Version: Both eyes move in the same direction to keep the visual axes parallel.
Vergence: Both eyes move in opposite directions to focus on objects at varying distances.
What is the primary action of the Medial Rectus muscle?
Adduction (moves the eye toward the nose).
Innervated by CN III (Oculomotor)
What is the primary action of the Lateral Rectus muscle?
Abduction (moves the eye toward the ear).
Innervated by CN VI (Abducens).
How do the Superior Rectus (SR) and Inferior Rectus (IR) muscles contribute to vertical eye movement?
SR: Elevates the eye when it is abducted.
IR: Depresses the eye when it is abducted.
How do the Superior Oblique (SO) and Inferior Oblique (IO) muscles contribute to vertical eye movement?
SO: Depresses the eye when it is adducted.
IO: Elevates the eye when it is adducted.
What are the primary, secondary, and tertiary actions of the Superior Rectus (SR) muscle?
Primary: Elevation.
Secondary: Intorsion.
Tertiary: Adduction.
What are the primary, secondary, and tertiary actions of the Inferior Oblique (IO) muscle?
Primary: Extorsion.
Secondary: Elevation.
Tertiary: Abduction.
What is the relationship between version and vergence eye movements?
Version: Both eyes move in the same direction to maintain parallel visual axes.
Vergence: Both eyes move in opposite directions (e.g., for focusing on near or far objects).
What are the types of vergence movements?
Convergence: Both eyes move inward (focus on near objects).
Divergence: Both eyes move outward (focus on distant objects).
Supravergence: One eye moves upward relative to the other.
Infravergence: One eye moves downward relative to the other.
Incyclovergence: Both eyes rotate inward along their vertical axis.
Excyclovergence: Both eyes rotate outward along their vertical axis.
What is Hering’s Law of Equal Innervation?
Hering’s Law states that for conjugate eye movements (version), when an impulse to perform an eye movement is received by one eye, the corresponding muscles of the other eye are equally innervated to maintain symmetrical eye movement.
What is Sherrington’s Law of Reciprocal Innervation?
Sherrington’s Law states that when one muscle contracts, its antagonist (opposing muscle) relaxes. This ensures smooth and coordinated movements.
What is the motility test used to assess?
The motility test assesses the extent and quality of eye movements, particularly for detecting comitant (constant) and incomitant (variable) deviations.
What is the difference between comitant and incomitant deviations?
Comitant deviations: The angle between the visual axes remains constant in all gaze directions.
Incomitant deviations: The angle between the visual axes changes with the direction of gaze, often due to pathology or trauma.
What is the procedure for performing a routine motility test?
Shine a pen light at about 40 cm from the patient’s face.
Move the pen light slowly through the six cardinal diagnostic positions of gaze.
Observe for any misalignments or discomfort in the eyes (check corneal reflex).
Record findings using version terminology (e.g., SAFE – Smooth, Accurate, Full, Extensive).
What is the purpose of the monocular motility test?
The monocular motility test helps differentiate between paresis (muscle weakness) and mechanical restriction of eye movements. It is particularly useful when incomitancy is suspected.
What is Duane’s Retraction Syndrome?
: Duane’s Retraction Syndrome is a congenital condition where the affected eye has limited abduction and retraction. It often causes horizontal deviations and is more common in females.
What is the difference between long-standing and recent onset incomitancy?
Long-standing incomitancy: Often does not require referral.
Recent onset incomitancy: Requires immediate referral for potential neurological assessment.
What is AHP (Aberrant Head Posture) in the context of ocular motility?
AHP is a compensatory posture that patients adopt to improve their binocular vision when there is an incomitant deviation, often seen in conditions like Duane’s syndrome.
What is the main sequence of saccades?
The main sequence refers to the relationship between the peak velocity of a saccade and its amplitude (size). As the amplitude of the saccade increases, the peak velocity also increases.
How do smooth pursuit movements differ from saccades?
Smooth pursuit movements are slow, continuous, and used to track moving objects, whereas saccades are rapid, abrupt movements that shift the gaze from one fixation point to another.
What is the Vestibulo-Ocular Reflex (VOR)?
The VOR helps maintain stable vision by moving the eyes in the opposite direction of head movement. It is triggered by stimulation of the semicircular canals and neck proprioceptors.
What is Optokinetic Nystagmus (OKN)?
Optokinetic nystagmus is a physiological response that occurs when watching moving objects that traverse the visual field. It consists of a slow tracking movement followed by a fast corrective saccade.
