Flashcards in Vestibular Ocular Reflex (M1) Deck (27):
What eye movements account compensate for relatively brief, transient head rotations and translations (walking)?
vestibular eye movements (vestibular ocular reflex, VOR)
When the head turns to the right, which horizontal canal is inhibited? 1. What are the yoked ocular muscles that are inhibited? 2
1. left horizontal canal
2. right lateral rectus and left medial rectus
What motions do the horizontal canals detect? 1. Does the canal depolarize or hyperpolarize when the head is rotated in the direction of the canal? 2
1. horizontal rotations
What is the gelatinous body that contains the cilia from the hair cells that make up the crista? 1. What is this responsible for? 2
1. the cupula
2. bows with the flow of endolymph and generates a directional response of the crista (either excitatory or inhibitory)
Which ocular muscles are linked to the anterior vertical canals?
1. ipsilateral recti
2. contralateral obliques
When the anterior vertical canals are stimulated, what are the yoked muscles that are stimulated?
1. ipsilateral superior rectus
2. contralateral inferior oblique
What are the mechanisms of the interaction between the stereocilia and the kinocilium?
1. bending of stereocilia towards kinocilium depolarizes the hair cell, increasing the firing of the nerve fiber
2. bending of stereocilia away from the kinocilium hyperpolarizes the hair cell, decreasing the firing of the nerve fiber
How are the semicircular canals arranged relative to each other?
orthogonally (90deg to each other)
What are found at the top of the each hair cell that make up the crista within the ampulla?
1. multiple stereo cilia of variable length
2. a single kinocilium at one edge
Which vertical canal is inhibited when the head is rotated to the left and then forward (down)? 1. What ocular muscles and inhibited? 2
1. left posterior canal
2. right inferior rectus and left superior oblique
Which canals are stimulated when the head is tilted backward (up)? 1. Inhibited? 2
1. posterior canals
2. anterior canals
What is the vestibular apparatus adjacent to and continuous with? 1. What is it filled with? 2
1. cochlea in inner ear
2. viscous endolymph
For the horizontal canals, is the cupula deflected towards or away from the utricle when it is stimulated?
When the head turns to the right, which horizontal canal is stimulated? 1. What are the yoked ocular muscles that are stimulated? 2
1. right horizontal canal
2. right medial rectus and left lateral rectus
Which canals are stimulated when the head is tilted forward (down)? 1. Inhibited? 2
1. anterior canals
2. posterior canals
Within the ampulla of the semicircular canals, what detects the flow and is a collection of sensory hair cells?
For the vertical canals, is the cupula deflected towards or away from the utricle when it is stimulated?
What portion of the vestibular apparatus detects linear acceleration (often gravity)?
What portion of the vestibular apparatus detects rotational acceleration?
the 3 semicircular canals
What is the latency for rotational VOR? 1. Is this considered fast or slow? 2
2. very fast
When the posterior vertical canals are stimulated, what are the yoked muscles that are stimulated?
1. ipsilateral superior oblique
2. contralateral inferior rectus
What is the flow of the endolymph inside of the canals relative to the direction of head rotation? 1. What is it detected by? 2
What are the names of the three semicircular canals?
1. lateral (horizontal)
2. anterior vertical
3. posterior vertical
Which ocular muscles are linked to the posterior vertical canals?
1. ipsilateral obliques
2. contralateral recti
Which ocular muscles are almost purely vertical acting when the head is rotated to the left?
1. the right recti muscles
2. left obliques
Which way do the eyes move relative to the head for VOR movements?
opposite to head movement