Neurophysiology: Vestibular System- Pt 1

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Questions and Answers

What is the primary function of the utricle and saccule?

To detect kinetic movement

To regulate body temperature

To detect sound waves

To detect linear acceleration, deceleration, and static tilt of the head (correct)

What is the name of the fluid that fills the semicircular canals?

Perilymph

Synovial fluid

Cerebrospinal fluid

Endolymph (correct)

What is the bilateral receptor system located in the membranous labyrinth?

Auditory system

Vestibular apparatus (correct)

Visual system

Olfactory system

What is the reason people feel dizzy after spinning around and suddenly stopping?

The endolymph in the ears is still moving due to inertia Signup and view all the answers

What is the central vestibular system located in?

The brainstem and cerebellum Signup and view all the answers

What is the name of the nerve that transmits information from the peripheral vestibular system to the central nervous system?

Vestibulocochlear nerve Signup and view all the answers

What is the function of the hair cells located in the macula of the otolith organs?

To detect linear acceleration and deceleration Signup and view all the answers

What is the name of the structures that make up the kinetic labyrinth?

Semicircular canals Signup and view all the answers

What causes the stereocilia to bend in the direction of linear acceleration?

Gravity and inertial forces acting simultaneously on the otolith Signup and view all the answers

What is the role of the otolith vestibular hair cells?

To either activate or inhibit to alert about a change in the position of the head Signup and view all the answers

What is the characteristic of vestibular hair cells at the resting stage?

They are tonically active cells Signup and view all the answers

Where do the sensory vestibular fibers arrive?

4 vestibular nuclei and the cerebellum Signup and view all the answers

What happens to the action potential frequency when the stereocilia are bent towards one side?

The frequency increases Signup and view all the answers

Where are the vestibular hair cell canals located?

In the cristae ampullaris of the semicircular canals Signup and view all the answers

What is the pathway of the vestibular nuclei to the spinal cord?

Lateral and medial vestibulospinal tracts Signup and view all the answers

What is the function of the cupula?

To cover the vestibular hair cells Signup and view all the answers

What is the function of the fastigial nucleus and flocculonodular lobe?

To process information from the vestibular nuclei and cerebellum Signup and view all the answers

What is the function of the thalamus in the vestibular pathway?

To relay information to the cortex for conscious vestibular information Signup and view all the answers

What happens to the cupula during angular acceleration of the head?

It is displaced Signup and view all the answers

What is the function of the maculae in the otolith organ?

To sense linear acceleration Signup and view all the answers

Why can someone feel the car stopping when they are blindfolded?

Because the macula of utricle is horizontally oriented Signup and view all the answers

Why can someone feel themselves going up or down when they are inside an elevator?

Because the macula of saccule is vertically oriented Signup and view all the answers

Study Notes

Vestibular System

Divided into peripheral and central systems
Peripheral system located outside of the brain, composed of vestibular apparatus in membranous labyrinth and vestibular portion of vestibulocochlear nerve (Cranial nerve 8)

Peripheral Vestibular System

Vestibular apparatus consists of 3 semicircular canals (kinetic labyrinth) and 2 otolith organs (static labyrinth)
Semicircular canals are filled with endolymph and surrounded by perilymph
Otolith organs consist of utricle and saccule, which detect linear acceleration, deceleration, and static tilt of the head

Central Vestibular System

Located in cerebellum and brainstem, contains 4 pairs of vestibular nuclei on each side
Functions include maintaining balance and coordination of eye-head-body movements

Vestibular Hair Cells

Located in macula of otolith organs
Tonic ally active cells at resting stage with constant firing rate
Bending of stereocilia towards one side increases action potential frequency, while bending in opposite direction decreases frequency
Change in frequency of action potentials indicates which side the body is moving
Hair cells in semicircular canals are covered by cupula, a gelatinous mass
During angular acceleration, cupula is displaced, causing excitation or inhibition of hair cells
All 6 canals activation provides precise indication of head movement in 3 dimensions

Otoliths

Located in macula of otolith organ, with otolith mass overlaying vestibular hair cells
Maculae have hair cells oriented in different directions to detect linear movement in different angles
Macula of utricle is horizontally oriented, while macula of saccule is vertically oriented
Maculae specialized for sensing linear acceleration, such as gravity acting on tilting head or head moving in straight line
Gravitational or inertial forces cause stereocilia to bend in direction of linear acceleration

Vestibular Pathway

Sensory vestibular fibers arrive at 4 vestibular nuclei and cerebellum
Cerebellum projects to vestibular nuclei, spinal cord, brain stem, and thalamus
Vestibular nuclei project to spinal cord, brain stem, cerebellum, and thalamus

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Description

Learn about the vestibular system, its peripheral and central components, and their roles in the human body. Quiz covers the membranous labyrinth and cranial nerve 8.