Vestibular System (2) Flashcards
What is vertigo?
Loss of orientation
Does vertigo occur with the eyes opened and closed?
Yes
What is damaged that causes someone to have oscillopsia?
Vestibular-ocular reflex
What does a lesion to the oculomotor system result in?
Oscillopsia
Diplopia
Nystagmus
What happens to postural control when there is a lesion?
Lack of stabilization (ataxia)
What can a lesion to the cerebellum lead to?
Supression of the VOR reflex
How does sound get transmitted to the labyrinth?
External auditory meatus
Tympanic membrane
Malleus, incus, stapes (sound amplification)
Oval window
Fluid movement in cochlea
Hair cells send signals to cochlear nerve
Pressure dissipated at round window
What causes sound dampening in the ear?
Tensor tympani (malleus)
Stapedius (stapes)
What is the labyrinth made up of?
Cochlea
Vestibule
Semi circular canals
What sends signals to the vestibular portion of CN 8?
Bending of hair cells in semi circular canals
What does the bony labyrinth contain?
Perilymph and suspends membranous labyrinth
What makes up the membranous labyrinth?
Cochlear duct
Utricle
Saccule
Semi circular canals
What is the membranous labyrinth filled with?
Endolymph
How many semi circular canals are there?
3 (anterior, lateral, posterior)
What do receptors in the semi circular canal detect?
Motion movement of Endolymph (only rotational acceleration)
What is the cristae ampullaris?
Epithelium at the end of the semi circular canal
What does movement of the cupula cause?
Hair cells to move and detect movement
What do hair cells consist of?
Sensory neuron, multiple small stereocilia, and a single large kinocilium
What does movement of hair cells towards the kinocilium result in?
Excitation
How does the cupula move?
Opposite way of the head
What do hair cells do when the head is stationary?
Baseline rate of firing
What do hair cells do when the head moves?
Cupula bends and moves hair cells
How do hair cells fire at a constant rate during constant movement?
Endolymph moves at the same speed
What plane is the utricle in?
Horizontal
What plane is the saccule in?
Vertical
Where are otolith organs located?
Cochlea and semi circular canals
What do otolith organs respond to?
Head position relative to gravity
Linear acceleration (not rotation)
What are macula?
Hair cells in gelatinous membrane with calcium carbonate crystals on top
What tilts the macula?
Changes in head position
What does bending of hairs in the macula stimulate?
Neuronal firing frequency in CN 8
What is the max response to the utricle?
Head upright and bending forward
What is the max response to the saccule?
Going from side lying to standing
