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33 Cards in this Set
- Front
- Back
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Double Vision is caused by?
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Lesions to extraocular muscles or nerves leads to misalignment of the eyes and diplopia.
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Saccades
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Brings new images of interest onto fovea, REM sleep.
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Smooth Pursuit
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Track moving objects, maintain image on fovea. Image necessary.
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Vergence
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Eyes moving laterally for distant objects and medially for close objects.
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Vestibulo-ocular reflex
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Maintaing focus while your head is moving.
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Optokinetic nystagmus
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Maintain focus while the object is moving, Head remains mostly still.
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Eye movements are controlled in the brainstem by the:
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Superior Colliculus-
Tells eyes how to move, directly communicates with ocular nerve. |
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General Functions of the vestibular system (3)
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1. Contribute to sense of movement and balance.
2. Stabilize vision during head movement. 3.Regulate postural tone. |
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Specific Functions of the vestibular system (3)
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1.Transduction of angular velocities and accelerations.
2. Transduction of linear velocities and accelerations. 3. Transduction of gravitational vector. |
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What sensations exist in the absence of Balance?
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Unsteadiness, Dizziness, Nausea, Motion Sickness, Vertigo.
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What are semicircular canals?
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3 tubes connected to the cochlea which transduce angular accelerations of the head.
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How do semicircular canals work?
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They are filled with fluid called endolymph. As the head tilts, the endolymph travels through the canals. In the canals there are cillia, when the endolymph rushes past it sends a signal to the brain denoting what motion is occurring.
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Horizontal semicircular canal detects...
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shaking head "no"
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Posterior semicircular canal detects...
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nodding
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anterior/superior semicircular canal detects...
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indian head shake
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What is the ampulla?
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the widest region of the semicircular canal. "equal specific gravity".
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What is the cupula?
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The gelatinous structure that interrupts endolymph flow at ampulla.
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What do cillia do?
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Transform mechanical energy into neural activity.
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These cillia are composed of many...
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...direction sensitive stereocilia and one kinocilium.
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When sterocilia are pushed towards the kinocilium the hair cell...
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Depolarizes.
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When the stereocilia are pushed away from the kinocillium the hair cell...
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Hyperpolarizes.
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Utility of otolith organs
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transduce linear accelerations of the head.
static head tilt. sensation of gravity |
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Utricle?
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Otolith organ that detects horizontal linear acceleration
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Saccule?
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Otolith organ that detects verticle linear acceleration
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How do otoliths work?
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When the head accelerates or tilts, gravity causes the otoliths to slide, pulling the stereocilia and causing the hair cell to depolarize.
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Ca++ carbonate crystals embedded into ______
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Macula
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Normal vestibular function relies on...
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...the equivalent relative densities of endolymph and the cupula.
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superior oblique
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intorsion
trochlear nerve |
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inferior oblique
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extorsion
oculomotor nerve |
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lateral rectus
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abducts
abducens nerve |
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superior rectus
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elevation
oculomotor nerve |
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inferior rectus
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depression
oculomotor nerve |
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medial rectus
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adducts
oculomotor nerve |
