Vestibular Function Flashcards
What is the function of the vestibular system?
Control of posture and balance
Where is the vestibular system found?
In the inner ear
In which bone are the labyrinths embedded?
Temporal bone
Which structures make up the vestibular apparatus?
3 semi-circular canals, utricle and saccule
What are the swellings at the bottom of the semi-circular canals called?
Ampulla
What are the utricle and saccule collectively known as?
Otolith organs
What is the function of the otolith organs?
They detect linear acceleration and the position of the head in space. Back/front tilt is detected by the utricle. Vertical movement is detected by the saccule
Which structure in the inner ear detects rotational movement?
Semi-circular canals
Which receptors are contained within the ampulla and what do they consist of?
Cristae - made up of cupula (a flexible gelatinous structure)
What is embedded in the cupula?
Cilia of hair cells that synapse directly with the sensory neurons of the vestibular nerve (CrN VIII)
How do the hair cells in the cupula detect rotational movement?
If the skull is rotated left or right from rest the endolymph does not move at first but the ampulla does because it is embedded in the skull. This produces a drag which bends the cupula and cilia in the opposite direction to movement
What are the two types of cilia of the hair cells?
One large kinocilium and progressively smaller stereocilia
What happens to AP discharge when the distortion of the cilia is in the direction of the kinocilium?
It is increased
What happens to AP discharge when the distortion of the cilia is away from the kinocilium?
It is decreased due to the hyperpolarization
Where does the integration of the sensory information from the cupula take place?
Cerebellum
