Vestibular System

Front 1

What is the function of vestibular system?

Back 1

Detect head movement. Maintenance of equillibrium.
Facilitation of extensor tone.
Stabilization/direction of gaze.
Contributes to spatial orientation.
Contribute to emotions - stability = fight or flight.
Autonomic function and conscioness.
Transduces forces associated with head acceleratin and gravity into biological signals.

Front 2

Development of the vestibular system: Prenatal?

Back 2

Begin developing soon after the neural tube cloases.
Myelinatin occurs at 5-6 months.

Front 3

Development of the vestibular system: Postnatal?

Back 3

Fairly well myelinated at bierth.
Continue to myelinate and develop until up to 10 years.

Front 4

Where the vestibular system located?

Back 4

Inner ear.
Deep within temporal bone.

Front 5

What the vestibular system consist of?

Back 5

Bony labyrinths.
Membranous labyrinths (inside bony labyrinths).
Hair cells.

Front 6

What makes up the receptors of the vestibular system?

Back 6

Otoliths contains Utricle and Saccule.
Samicircular Canals contains Anterior canal, Posterior canal & Horizontal canal.

Front 7

What is the function of Otoliths?

Back 7

Respond to head position relative to gravity.
Respond to linear acceleration and deceleration: Utricle = horizontal and Saccule = verticle.
Important in the maintenance of postural reflexes.

Front 8

Explain anatomy of Otoliths.

Back 8

Macula is a specialized receptor = raised portion.
Macula contains hair cell embedded in gelatinous mass called otolithic membrane.
Membrane covered by calcium carbonate crystal called Otoconia.

Front 9

Explain how Otoliths work?

Back 9

Change in head position --> Force of gravity causes displacement of otoconia --> Hair cells bend. Stimulation = depolarization. Inhibiting = hyperpolarization.

Front 10

Explain how Utricle work?

Back 10

Macula on floor of utricle when head is upright.
Orientation is horizontal.
Responds to head tilts with head upright.
Responds to linear acceleration and deceleration.

Front 11

Explain how Sccule work?

Back 11

Macula is orented vertically.
Responds maximally when head moves from laterally flexed position (side-lyting to standing).

Front 12

What is the function of Semicircular Canals?

Back 12

Detects angular and rotatry movement = Acceleration & Deceleration.

Front 13

Explain anatomy of semicircular canal.

Back 13

Consists of anterior, posterior and lateral (horizontal) semicircular canal.
Hollow rings arranged perpendicular to each other.
Works in pairs.
Filled with fluid call endolymph.
Each has a swelling called ampulla that contain crista.

Front 14

What is Ampulla?

Back 14

Specialized receptor contains crista. Crista consists of supporting cells and sensory hair cells.
Cells are embedded in a gelatinous mass called the cupula.

Front 15

Explain how semicircular canals works?

Back 15

When head is rotated, the force of the endolymph acts against the cupula, displacing the hair cells.
Bending of hair cells leads either to deporlarization or hyperpolarization.

Front 16

Explain how information travels in the semicircular canals.

Back 16

Information from semicircular canals and otolithic organs is transmitted by the CN 8- Vestibular-Cochlear Nerve.
Most information is sent to the vestibular nuclei in the brainstem.
Some information is sent directly to the cerebellum.

Front 17

Describe the vestibular nuclei in the brainstem.

Back 17

4 pairs of nuclei = Pons & Medulla.
Send & receive information of cerebral cortex.

Front 18

What is the vestibular pathway?

Back 18

Medial Longitudinal Fasciculus (MLF) = White matter.

Front 19

Where Medial Longitudinal Fasciculus (MLF) project to?

Back 19

Extaocular muscle nuclei (CN 3, CN 4 & CN 6).
Superior colliculus
Spinal accessory nuclei.

Front 20

What is the function of Medial Longitudinal Fasciculus (MLF)?

Back 20

Vestibular-ocular responses.
Control eye movements.
Coordinated movement of eyes and head.

Front 21

What is Vestibulo-ocular reflex (VOR)?

Back 21

Stabilize visual images during head movements.
Compensatory eye movement in response to movement to stabilize gaze.

Front 22

What is Nystagmus?

Back 22

Involuntary, rapid back and forth movement of the eyes.
Suring and following rapid rotation of the head.
Normal secondary to the endolymph still moving when the head is still.

Front 23

What is Congenital nystagmus?

Back 23

Condition that eyes move back and forth, rapidly and constantly.

Front 24

What is Optokinetic reflex?

Back 24

Adjust eye position during slow head movement.

Front 25

Name 2 vestibulo-spinal tract of the vestibular pathways.

Back 25

Lateral vestibulo-spinal tract
Medical vestibulospinal tract.

Front 26

Explain Lateral vestibulo-spinal tract.

Back 26

From vestibular muclei to spinal cord.
Ipsilateral projection to postural muscles in the limbs and trunk.
Facilitates extensors while inhibiting flexors.

Front 27

Explain Medial vestibulospinal tract.

Back 27

From vestibular nuclei to spinal cord.
Bilateral projection to cervical & thoracic levels (neck & upper back).
Adjust head position to upright.
Facilitate extensors in posture.

Front 28

What is Vertigo?

Back 28

An illusion of motion.
Occurs with both central and peripheral disorders.

Front 29

What is Benign paroxysmal positional vertigo (BPPV)?

Back 29

Acute onset of vertigo.
Subsides in less than 2 minutes.
Occurs during occupations such as getting out of bed or reaching up.

Front 30

What is Meniere's Disease.

Back 30

Abnormal pressure in the inner ear.
A sensation of fullness in the ear.
Tinnitus = ringing in the ear.
Severe acute vertigo.
Nausea, vomitting, hearing loss.

Front 31

What is vestibular rehabilitation?

Back 31

A non-invasive approach for patients with vestibular and balance disorders.
A systematic, individually designed regimen of exercises and activities that address the unique needs of individual patients.

Front 32

What is the goal of vestibular rehabilitation?

Back 32

Decrease frequency, intensity, and duration of vertigo.
Decrease related symptoms such as headache, nausea, and lightheadedness.
Improve balance.
Increase independence in daily life.
Develop compensatory strategies for coping with dizziness, disequilibrium and anxiety.

Front 33

What is Sensory Integration Dysfunction?

Back 33

Gravitational insecurity.
Intolerance or aversive response to movement.
Under-responsiveness.
Postural deficit.