Vestibular system Flashcards
What are the main inputs and outputs of the bodies balance system?
Input: eyes, inner ear (rotation/gravity), pressure
All pass by the CNS, and then REFLEX response mostly to occular and postural (reflex to be fast)
if it goes wrong, can cause nausea
What is the inner ear other name?
Labyrinth-carved inside the temporal bone
Cochlear part and vestibular part (that one is for balance
All filled with fluid
What are the 5 organs of the vestibular?
Utriculus and succular-2 balls. Sacculus connected to cochlea
Superior, posterior and lateral cannal to utricule
each canal has an ampulla (ampulla side is the one where there is not two canal together)
What is the stimulus for the vestibular system?
The stimulus is movement-movement of fluid within the cannals
The cannals-posterior and superior/left/right anterior and 45degrees each side and the lateral is horizontal
each form one of the 3D planes
What cells are found within the vestibule allowing transduction of sensation?
Type I and II hair cells, which transduce
Type I-more in number, direct afferent, inderect efferent
Roundish shape
Type II-more efferent, less afferent, shaped more like a rectangle
All found together-mainly in 2 areas of the utricule and the saccule (bottom of the saccule, and cochlear side of the utricule (sideways) -respond to up and down and sideways movements
Utricule is very good to transduce horizontal plane movements
Saccule transduce vertical plane movement
How do the organs of the vestible transduce vertical and horizontal movement
the hair cells of the vestible
mainly in 2 areas of the utricule and the saccule (bottom of the saccule, and cochlear side of the utricule (sideways) -respond to up and down and sideways movements
Utricule is very good to transduce horizontal plane movements
Saccule transduce vertical plane movement
What other things do you find in the hair cell areas of the vestible?
Called the maculae
You find hair cells, but also a gelatinous matrix that helps hair cells move together
Then on top, otoliths (crystals)
What is the roles of the otoliths organs?
the crystals are loose on top of the jelly, and when you move they will pressure the cells and allow transduction
Allows better view of linear acceleration and tilt
What is the striola in the vestiule maculae?
Central part of the maculae-the hair cells have opposing hair bunds polarities
BOTH ORGANS HAVE THE SAME Thing
The maculae have opposite polarites delimited by the center-the striola (polarity decided by which large cilia in “in front”-and the sides ae mirrored
So when one side is activated (move one way), the ones on the other side move the same way, but causes inhbition either-double down on the information (and helps with the recovery as double)
What is the role of the semicircular cannals?
Hair cells are only in the ampulla-
The ampulla has hair cells and a thinner gelatin called cupulla-liquid moves the cupulla and move hair-depending on side-excite or inhbit
Redundant in some ways with the uticle and succula but allows faster and safer-redundency also comes from the OTHER ear, which has hair the other way
In the ampulla, no mirror/striola-all hair cells going one way
Good for angular tilt accelleration
What is the blood supply to the inner ear and especially with the vestibule?
From the basilar artery, via the anterior inferior cerebral artery-which also goes to cerebellum and brain stem–
If localised to inner ear fine, but can be result of stroke
So can have symptoms of inner ear issue but be having an anterior cerebral artery
Where does the information from the vestible go first?
Vestibular nerve-seperated in the superior and inferior vestibular nerve
Tests only really test the superior part
In the brainstem, goes to vestibular nuclei–reflex center and thats where most of the action is
What different parts of the vestibular nuclei are there? Where do they signal too?
Superior, lateral, medial, inferior
Infomation from vestibule and coordinate all the information to generate reflexes-generate down via spine, but also to the occulormotor nuclei
Also signals to cerebullum and the centers for CVS and respiratory (why nausea can be so distressing)
ALso projection to thalamus then somatosensory cortex-orientation
Summary
Vestibulospinal reflex (limb. trunk. Upper back.neck)
Vestibulocerebellar (to vestibulocerebellum (top andbottom) (feedback-and cooredinate movement, posture regulation, VOR (eye) modulation)
Vestsinulo-occular reflex
Ventroposterior nucleus-vestibular cortex (unsure where this is tho)
Overall what is the function of the vestibular system?
Balance
Posture control
Keep the images not moving when u are
Constantly working-and why we can stand up-gravity is stimulus. What activating the cells do is increase the normal activity. inhbition reduces it
Does the vestibular system work when youre immobile?
Constantly working-and why we can stand up-gravity is stimulus. What activating the cells do is increase the normal activity. inhbition reduces it
