Wednesday, April 3, 2013

Vestibular nerve, pathway and mnemonic for the receptors

Hello everyone! We'll finish off the vestibulocochlear nerve today :)
It isn't as hard as it seems, trust me <3

Vestibular receptors are:

The macuLae of the utricLe and saccuLe
And what do they sense? Linear acceLeration

The Cristae of the semiCircular canal
And what does it sense? Circular movements (rotatory)

It's a no brainer really =D

The ganglion is situated in the internal acoustic meatus, the central processes of the neurons of the ganglion form the vestibular nerve which ends in the vestibular nucleus

These nuclei send fibres to the:
Archicerebellum forming the vestibulocerebellar tract
Anterior horn of the spinal cord forming the vestibulospinal tract
Motor nuclei of 3, 4, 6 cranial nerves in the brainstem through the medial longitudinal bundle

It makes sense why this happens
You need to tell the cerebellum what is going on for the maintenance of equilibrium, position and tone of the trunk muscles (this happens via the vestibulospinal tract)

And if you want to maintain a fixed gaze on an object while your head is moving, you need to tell your eyes that your head is moving
"Hey dude, I'm turning my head to the other side but keep an eye on what I was lookin' at" :P
That's your vestibulo-occular reflex

For example,
If your head rotates to the right,
Your right vestibular nerve will tell your:
Right occulomotor nucleus to contract the medial rectus
& Left abducens nucleus to contract the lateral rectus.
So your eyes will look left <_<

That's all!

I'm sorry for the lack of images in this one, a bit caught up
I'll try to upload em only if you guys really need it
I think it's understandable without images too

Happy studying xoxo
-IkaN



2 comments:

  1. 'Motor nuclei of 3, 4, 7 cranial nerves in the brainstem through the medial longitudinal bundle'
    Mistake - not to 7 cranial nerve, but to 6!!

    ReplyDelete
    Replies
    1. Typing mistake, my bad ^_^"
      Thank you for the correction! :)

      Delete

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