Vestibular Anatomy

Descending tract that is ipsilateral through the entire spinal cord

Lateral Vestibulospinal Tract

Tract that has excitatory effect on trunk and limb extensors and inhibitory effect on flexors

Lateral Vestibulospinal Tract

This type of VOR compensates during translation

Linear VOR

3 Major Components of Vestibular System

Peripheral Sensory Apparatus, Central Processing System, Motor Output System

Vestibular Nuclear Complex is located in the ____ & ____ consists of ________

Pons, Medulla, 4 Vestibular Nuclei- Superior, Medial, Lateral, Inferior

The gain of the VOR is ______________ and is regulated in part by the _________.

Ratio of head to compensatory eye movement, Cerebellar Flocculus

If you have 2 targets and you look at 1 then the other this is an example of

VOR cancellation

Turning the head back and forth while maintaining your gaze on a stable object is an example of

VOR x1

Moving an object opposite the direction that you are turning your head is an example of

VOR x2

Output of the central vestibular system (through the vestibular nuclei) travel to the ocular muscles serving the ____ reflex and to the spinal cord serving the ____ reflex

VOR, VSR

The primary function of the semicircular canals is to sense _______ acceleration of the head and are most sensitive to ______ frequency motion with an example being _____.

Angular, Higher Frequency, Gait

Posterior canal shares the same plane as the contralateral _________ canal

Anterior

Hair cells in the ampula send its signal to the _______ cells in the internal auditory meatus, here the vestibular ganglion sends neurons to the __________ and the _________ lobe of the Cerebellum

Bipolar, Vestibular Nuclei in the brainstem, Flocculonodular

Peripheral Sensory Apparatus contains....

Bony Labyrinth (located within the temporal bone), Membranous Labyrinth, and specialized hair cells

Major processor for unconscious proprioception

Cerebellum, esp. middle or vermis

This type of reflex can be used to help substitute for VOR in patients with bilateral vestibular loss to increase gaze stabilization

Cervico-ocular reflex

Vestibular Nuclei recieve input from the _______ Vestibular Nerve, ________ Vestibular Nuclear Complex, Cerebellum, Brainstem reticular activating system, Spinal Cord

Ipsilateral, Contralateral

Head tilt to the right will stimulate both the otoliths and semicircular canals. The stimulation of the otolith results in transmission of impulses to the S.C. via the _______.

LVST

Lateral nucleus is the origin for the _________ vestibulospinal tract and is also known as _______ nucleus

LVST, Deiters

Spinal Anterior Horn cell activity is influenced by information from the semicircular canals and the otoliths through 3 major pathways

LVST, MVST, RST

Bony Labyrinth contains....

3 Semicircular Canals and the vestibule

Crista receptors are sensitive to _______ acceleration such as turning your head

Angular

This type of VOR compensates for rotation and is primarily responsible for gaze stabilization

Angular VOR

RST recieves input from the _______ and acts to mediate ______________.

4 Vestibular nuclei, Postural Adjustments

Membranous Labyrinth contains...

5 sensory organs of the Peripheral Vestibular System

Primary roles of the Cerebellum in the vestibular system

Adaptive Processor, Monitors Vestibular Performance

The ______ is the enlarged area at the end of the canals which contains _____. Hair cells are found within the ______.

Ampula, Crista, Crista

Endolymph that does not drain into the venous sinuses causes too much fluid to build up and results in swelling of the ________ and ___________. This can cause dysfunction of the ________ & _______system because hair cells are firing even when there is no stimulation.

Cochlear Duct, Saccule, Auditory, Vestibular

Receptor in the semicircular canal is known as the _____

Crista

Gelatinous membrane called the ______ overlies each set of hair cells in hte ________. Calcium Carbonate crystals called _______ are located in the gelatinous membrane of the _______.

Cupula, Semicircular Canals, Otoconia, Otolith

When you turn your head to the right, hair cells in the maccula causes the horizontal canal on the right to ___________ and _______ on the left.

Depolarize, Hyperpolarize

Peripheral Sensory Apparatus is responsible for what 2 things

Detecting and relaying info about Head Angular and Linear Velocity to the Central Processing System, Orientation of the head with respect to gravity

A flu or cold increases the pressure in the _______________ tube which may cause a person to feel dizzy

Eustachian Tube

Central Processing System works with what 3 sensory inputs to provide info about the position and movement of the head in space

Input from the Peripheral Sensory Apparatus, Somatosensory, and Visual system

During head movements, posture, & Gait, what action do Motor Outputs generate?

Generate Compensatory Eye Movements (for gaze stability) & Compensatory Body Movements (for postural stability)

Head movement to the left causes an _______ in the firing rate of the left CN VIII, and an ______ in the firing rate of the right CN VIII

Increase, Decrease

Peripheral Sensory Apparatus is located in the _____, the Central processing system is located in the _______, and the Motor Output System is mediated through the ______ & ______ reflex.

Inner Ear, Vestibular nuclear complex in the brain stem and cerebellum, VOR & VSR

Otolith detects _______ acceleration of the head. More specifically, the utricle detects _______ and the saccule detects _______. The Otolith is most sensitive to ____ frequency motion with an example being ________.

Linear, Horizontal Plane Linear Acceleration, Vertical Linear Acceleration in the Sagittal plane, Lower Frequency, Standing in place

Macula is the receptor for _______ acceleration, contain calcium carbonate crystals called ________

Linear, Otoconia

what is the sensory organ of the utricle and saccule

Macula

Role of the VSR during head movements, locomotion and posture

Maintain whole body equilibrium by facilitating and inhibiting skeletal extensor muscle activity

This tract descends bilaterally and terminates in the cervical and thoracic region and has exitatory and inhibitory effects on neck musculature

Medial Vestibulospinal Tract

This tract is associated with vestibullocollic reflex which is a series of responses that stabilize the head in space

Medial Vestibulospinal Tract

A disorder of endolymphatic drainage resulting in unilateral hearing loss, horizontal nystagmus, tinnitus

Menieres

A lesion to the ________ part of the cerebellum will primarily affect the VSR and will result in what?

Middle (Vermis), Postural and Gait Instability

The duration of VOR response and Otolith input is adjusted and processed in the _______

Nodules-Cerebellum

The Membranous Labyrinth consists of 2 swellings. What are they

Otolith (Utricle and the Saccule) and 3 semicircular canals

LVST linds directly with alpha and gamma motoneurons of the anterior horn cell and controll _____________

Otolith Mediated Postural Responses

A head tilt to the right will result in an increase in extensor activity on the _____ and an increase in flexor activity on the ______ via the LVST to stabilize the head and body.

Right, Left

30 degrees of head rotation to the left is accompanied by 30 degrees lateral eye movements to the ____ due to activation of the left ______ and the right ______, this is due to the gain of the VOR with the ratio of head to eye movement being close to ___.

Right, Left Medial Rectus, Right Lateral Rectus, 1

Which otolithic organ responds to acceleration within the saggital plane like riding an elevator

Saccule

Hair cells are located in the.....

Saccule, Utricle, and cristae of Semicircular canals

With head movement you have afferent input from the _________ ascend to the _______ and is primarily responsible for producing compensatory eye movements

Semicircular Canals, Vestibular Nuclei

Each hair cell contains many _________ and 1 ________

Stereocilia, Kilocilium

Which otolithic organ responds to balance and righting reactions with position of the body

Utricle

Because the utricle and saccule are sensitive to gravity or linear acceleration, bending your head foward will stimulate the _______ while bending your head to the side will stimulate the ________

Utricle, Saccule

Afferent signals from the Labyrinths travel via CN VIII to the _______ & _________

Vestibular Nuclear Complex, Flocculonodular Lobe of the Cerebellum

Efferent input from the ________ travel to the _____________, and then to the output neurons of the VOR which are CN ___,____,& ____ controlling eye movement

Vestibular Nuclear Complex, Ocular motor nuclei, CN III,IV&VI

Efferent signals from the __________ go to the _________, Cerebellum, Brainstem reticular activating systems, parietal cortex, ________ Vestibulospinal tract, and __________ Vestibular Nuclear Complex

Vestibular Nuclear Complex, Oculomotor Nuclei, Ipsilateral, Contralateral

Central Processors of the Vestibular System

Vestibular Nuclei, Cerebellum

Each ___________ maintains a baseline firing rate that is symetrical at rest, with head movement a change in firing rate will occur in ______ directions

Vestibular Nuclei, Opposite

VSR reflexes

Vestibulocollic, Labyrinthin reflexes

MVST has an __________ effect on most neurons

inhibitory

A head turn to the right will cause displacement of the hair cells in the ampula to the _____

left

Spinning to the right can elicit nystagmus, which will begin with VOR pattern or slow movement to the ______ followed by a compensatory rapid eye movement to the ______ (VOR with corrective saccade)

left, right

Primary function of the VOR

maintain faze stability during head motion

Pathway for modulating tone and postural control

reticular spinal tract

Components of the peripheral sensory apparatus

semicircular canals, otolith, CN VIII