Vestibular Proprioception

What input is needed for proprioception of the head?

Vestibular proprioception from the head

What is the sense of where the head is in space?

Vestibular Proprioception

Vestibular proprioception is generated by what structure?

Vestibular apparatus in the inner ear

What are the three main functions of output from the vestibular nuclei?

-Maintain visual field

-Control level head position

-Compensate for head movements to maintain upright stance

What are the peripheral vestibular structures?

-Vestibular Apparatus

-Vestibular Nerve

-Vestibular Ganglia

The vestibular nuclei is located in the...

Medulla

What structures involved in vestibular proprioception are a part of the CNS?

-Medulla

-Cerebellum

What cranial nerves are involved with maintaining steady visual field (nystagmus) via vestibular nuclei projections.

-CN III

-CN IV

-CN VI

CN III innervates what muscles of the eye?

-Dorsal Rectus

-Medial Rectus

-Ventral Rectus

-Ventral Oblique

CN IV innervates what muscle of the eye?

Dorsal Oblique

3 multiple choice options

CN VI innervates what muscle of the eye?

Lateral Rectus

3 multiple choice options

A head turn to the left stimulates the (right/left) vestibular apparatus and inhibits the (right/left) vestibular apparatus and vice versa.

Left; Right

1 multiple choice option

What would be the process of a vestibulo-ocular reflex for a left head turn?

Left vestibular nerve triggers the ipsilateral vestibular nuclei, which travels along the ascending MLF across to the contralateral abducent nucleus, triggering the contraction of the lateral rectus, moving back across to the ipsilateral oculomotor nuclei in the midbrain

What is the slow phase of nystagmus of a left turn of the head?

Eyes slowly turn to the right

What is the fast phase of nystagmus of a left turn of the head?

Eyes jerk back to the left and rest to the center

The fast phase of nystagmus is controlled in the...

Pons

T/F: The fast phase of nystagmus is always towards the side with the more active vestibular system.

True

1 multiple choice option

When a lesion unilaterally damages the vestibular apparatus, nerve or nuclei, what can occur?

Spontaneous Nystagmus

The fast phase of nystagmus occurs (toward/away) from a lesion?

Away

1 multiple choice option

What is the pathway of the vestibulo-collic reflex?

Vestibular nerve -> ipsilateral vestibular nuclei -> descending arm of ipsilateral medial longitudinal fasciculus (vestibulospinal tract) -> ipsilateral cervical spinal gray matter -> excitation or inhibition of LMNs to epaxial cervical muscles

A unilateral lesion of the vestibular system will affect the (ipsilateral/contralateral) neck muscles, causing the head to tilt towards the lesioned side.

Ipsilateral

1 multiple choice option

Changes in posture are induced by the...

Vestibulospinal Tract

What is the vestibular pathway for maintaining posture?

Vestibular nerve -> Ipsilateral vestibular nuclei in the medulla -> Ipsilateral spinal cord ventral funiculus (vestibulospinal tract) -> ipsilateral spinal gray matter LMNs axial muscles and ipsilateral limb extensor muscles

When the head moves to the right, activity of the (left/right) CN VIII will increase and decrease on the (left/right) side.

Right; Left

1 multiple choice option

When the vestibular system is unilaterally damaged, the extensor muscles on the (ipsilateral/contralateral) side of the damage will lose input.

Ipsilateral

1 multiple choice option

T/F: The direction an animal leans, circles, or rolls toward is considered the side with a lesion of the vestibular system.

True

1 multiple choice option

Unilateral lesions affecting posture and balance cause...

Leaning, falling, rolling, toward less active side (the side the lesion is on)

When it comes to posture, what should you look for when assessing vestibular dysfunction?

-Postural reaction deficits in limbs

-UMN signs in limbs

T/F: In either peripheral or central vestibular dysfunction, the normal side will have normal to enhanced extensor thrust compared to the lesion side.

True

1 multiple choice option

T/F: The periphery sensory axons of the vestibular nerve are the only such that have direct access to the cerebellum.

True

1 multiple choice option

Purkinje cells in the cerebellar flocculonodular node project directly out of the cerebellum and terminate in the...

Ipsilateral vestibular nuclei

Unilateral cerebellar lesions involving the flocculonodular lobe produce a set of signs called...

Paradoxical Vestibular Syndrome

Loss of the normal Purkinje cell output from the damaged side of the flocculonodular lobe means the ipsilateral vestibular nuclei will be (less/more) active than normal.

More

1 multiple choice option

With paradoxical vestibular syndrome, the normal side is the (less/more) active side and is where signs occur.

Less

1 multiple choice option

A right side FN (flocculonodular lobe) unilateral lesion means what signs...

-Increased activity on right side

-Head tilt to the left

-Fast phase of nystagmus to the right

-Leaning/rolling to the left.

A left side FN (flocculonodular lobe) unilateral lesion means what signs...

-Increased activity on the left side

-Head tilt to the right

-Fast phase of nystagmus to the left

-Leaning/rolling to the right

A left side unilateral peripheral lesion of the vestibular system leads to...

-Less activity on the left side

-Head tilt to the left

-Fast phase of nystagmus to the right

-Leaning/rolling to the left

A right side unilateral peripheral lesion of the vestibular system leads to...

-Less activity on the right side

-Head tilt to the right

-Fast phase of nystagmus to the left

-Leaning/rolling to the right

With paradoxical vestibular syndrome, the fast phase of nystagmus happens (toward/away from) the lesioned side?

Toward

1 multiple choice option

With paradoxical vestibular syndrome, head tilt goes (toward/away from) the lesioned side?

Away from

1 multiple choice option

With paradoxical vestibular syndrome, the animal leans/rolls (toward/away from) from the lesioned side?

Away from

1 multiple choice option

T/F: In more common vestibular nuclei disorders, vestibular signs and proprioceptive deficits will involve the same side of the body as the lesion.

True

1 multiple choice option

T/F: In the paradoxical disorder, vestibular signs seem to point towards both sides of the body.

True

1 multiple choice option

When it comes to common vestibular disorders and also paradoxical disorder, why will there always be proprioceptive/UMN deficits in the limbs on the side of the lesion?

Because the medulla and cerebellum are concerned with the ipsilateral side of the body

If inhibition from the flocculonodular lobe is disrupted by a unilateral lesion, then the ipsilateral vestibular nuclei will become (more/less) active.

More

1 multiple choice option

Output from what structure provides normal inhibition to the vestibular nuclei?

Flocculonodular Lobe

If inhibition from the flocculonodular lobe is disrupted by a unilateral lesion, then the (lesioned/normal) side will be more active.

Lesioned

1 multiple choice option

What are the signs of peripheral vestibular unilateral lesions?

-No postural reaction deficits

-Leaning/rolling towards less active (lesion) side

-Head tilt towards less active (lesion) side

-Fast phase of nystagmus towards more active (normal) side

-Horner's signs

What are the signs of central vestibular unilateral lesions in non-paradoxical disorders?

-Postural reaction deficits on lesioned side

-Leaning/rolling towards less active (lesion) side

-Head tilt towards less active (lesion) side

-Fast phase of nystagmus towards more active (normal) side

-No Horner's Signs

What are the signs of central vestibular unilateral lesions in paradoxical disorders?

-Postural reaction deficits on lesioned side

-Leaning/rolling towards less active (normal) side

-Head tilt towards less active (normal) side

-Fast phase of nystagmus towards more active (lesion) side

-No Horner's Signs

What two structures contain perilymph?

-Scala Vestibuli

-Scala Tympani

What structure contains endolymph?

Scala Media

3 multiple choice options

What structure produces endolymph?

Stria Vascularis

What structure is the main sensory cell of the vestibular system?

Inner Hair Cell

What structure of the vestibular system regulates sensitivity?

Outer Hair Cell