Motor Control 4 Flashcards
What does the Vestibular system do?
Process sensory information related to head position, spatial orientation (with respect to gravity) and movement
What is the vestibular bony ‘labyrinth?
Part of the vestibular system responsible for balance and the position of the body in space
Where is the bony labyrinth found?
In the temporal bone
What is perilymph?
The substance that separates the membranous labyrinth from the bony labyrinth
What is endolymph?
The liquid inside the bony labyrinth
What is the structure of the labyrinth in the inner ear?
3 semicircular canals (anterior, posterior, lateral), positioned in line with each plane of movement
What plane is the anterior semi-circular canal in?
Frontal plane
What plane is the posterior semi-circular canal in?
Saggital Plane
What plane is the lateral semi-circular canal in?
Transverse Plane
What is the name of the enlarged section of each semicircular canal where it connects with the Utricle?
Ampullae
What is located within the Ampullae?
The Crista Ampullaris
What does the cupula around the crista ampullaris do?
It deforms due to angular acceleration of the head which stimulates hair cells in the crista ampullaris which sends signals to the brain to detect angular head motion
What is the crista ampullaris?
A cone shaped structure in the ampullae covered in hair cells that detect angular acceleration
What are the 5 sensory organs of the Labyrinth?
3 Semicircular canals
2 Otolith Organs (Utricle and Saccule)
What is kinocilium and stereocilia?
Kinocilium: Longer hairs on the hair cell
Stereocilia: The shorter hairs of the hair cells
What occurs if the kinocilium deflects towards the stereocilia?
Decrease of firing rate/hyperpolarisation
What occurs if stereocilia deflect towards the kinocilium
Increase in firing rate/depolarisation
If you angularly accelerate in one direction, what direction will the endolymph move in as you accelerate?
the other direction
If you angularly accelerate in one direction, what direction will the endolymph move in once you start to decelerate?
The same direction as you moved
How does activity of one semicircular canal affect the other?
It inhibits the opposite side
If the head accelerates in a counterclockwise direction, explain what will happen in the semicircular canals of both sides of the head
Endolymph will travel clockwise, which will cause depolarisation/increased firing rate of the left side, and hyperpolarisation/decreased firing rate on right side. Both will send excitatory signals to their own side and inhibitory signals to the opposite side, but as the right side is decreased firing rate, it does not inhibit the left side much, but the left side does inhibitthe right side a lot
What is the macula?
A patch of the epithelium of the utricle and saccule that has hair cells on it
How are the hair cells orientated on the macula?
They are not all in the same direction.
What can (the hair cells on) the macula detect?
Head tilt and linear acceleration, and position with respect to gravity
Where are the saccule and utricle found?
In the vestibule
how do the hair cells on the macula of the utricle/saccule detect head tilt?
Otolith crystals that sit on top of them will be affected by gravity when the body accelerates linearly or tilts, shifting the hair cells and affecting the firing rate
What is relationship between strength and length of stimulus, and the response?
Stronger stimulus leads to stronger response with shorter latency
Longer stimulus means longer response
What are the two ways higher levels of the brain can modulate reflex mechanisms?
Reflex suppression (raises threshold for reflex excitation) Reflex Potentiation (lowers the threshold for reflex excitation)
