Lecture 27+28: Special proprioception and the vestibular apparatus

Question 1

The widespread influences of the vestibular system in the brain (locations)

Answer 1

• Cortex
• Spinal cord
• Cranial nerves (III,IV,VI) - eye stuff
• Cerebellum
• Emetic center (vomiting)

Question 2

The inner ear: vestibular apparatus

Answer 2

Series of fluid-filled membranes
Membranous labyrinth
Fluid: endolymph
In petrous part of temporal bone
Caverns in bone: bony labyrinth filled with perilymph.

Question 3

Sacs in the ear

Answer 3

The biggest sac is the utriculus (utricle) and the little one is the sacculus (saccule).
Helps detect linear acceleration
* There is a macula inside each sac
* Neuroepithelium line the macula (the hair cell, a mechanoreceptor… on each hair cell is the kinocilium and they have stereocilia)
* The adequate stimulus is the bending of the cilia and it matters which way it bends

Question 4

The three loops of the inner ear

Answer 4

semicircular ducts. The dilation is the ampullae. There are three. Also neurendolthelium (crista ampullaris) in here. Deleted rotational (angular) acceleration like when you turn your head. There are three because (3D)

Question 5

Vestibular targets

Answer 5

• Vestibular apparatus > detects ACCELERATION
• Paired nature of vestibular apparatus one side firing more, one side firing less…
• Vestibular appartus > vetibular n> vestibular nuclei
• Vestibular nuceli have TONIC ACTIVITY (depolarize and repolarize)

Question 6

Three (normal) vestibular reflexes

Answer 6

• Vestibuloocular reflex: exists so we can maintain steady clear vision, eye movement to keep eye on target.
  (Steady velocity rotation. = becomes equal right to left. When you stop spinning)
• Vestibulocollic reflex (neck) (Keep the head level by adjusting the neck. Extension of the neck.)
• Vestibulospinal reflex
  Is to the rest of the body and the limbs what the vestibulocollic is to the neck. We have an extension to overcome falling. Lateral vestibulospinal tract