Cerebellum and Vestibular System

Which peduncle do the the dentate and interposed nuclei send fibers out of and where do they go ?

Superior Cerebellar Peduncle Red nucleus or thalamus but some descend to inferior olivary nucleus

Kinocilium

Tallest projection of stereocilia

Stereocilia

Taper in length Differences in the arrangement determine which stimuli they respond to

Maculae

Utricle Saccule

Internal acoustic Meatus contains what nerves

VIII- Vestibulocochlear VII - Facial

What are the longitudinal zones from medial to lateral

Vermis Medial hemisphere Lateral hemisphere

Fastigial

Vermis - most medial

Purkinje cells project to what structures to provide the output of the cerebellar cortex

Vestibular Nuclei Deep Cerebellar Nuclei ****

What are the 4 main inputs that the MOSSY fibers carry into the cerebellum ?

Vestibular nerve and nuclei Spinal cord Reticular formation Cerebral cortex - through middle peduncle

Otoliths

clumped crystals that sit atop the gelatinous substance Linear acceleration

What does damage to the flocculus affect ?

equilibrium and eye movements

Sensory input enters the cerebellum -->

exits to the thalamus or brainstem

Ataxia

incoordination or clumsiness NOT due to weakness

Superior Cerebellar Peduncle

mostly efferents to red nucleus and thalamus

Postrotatory nystagmus

occurs after rotation stops and the cupula deflects in the opposite direction

Romberg Test

to distinguish sensory ataxia (dorsal column/vestibular involvement) from cerebellar ataxia

Vermis affected -->

truncal ataxia

Romberg's sign

the standing patient is asked to close his or her eyes. An increase loss of balance is interpreted as a positive Romberg's test

Middle Cerebellar Peduncle

Afferents from contralateral pontine nuclei

What detects angular acceleration ?

Anterior Posterior Horizontal Semicircular duct

The primary fissure separates the ..

Anterior and posterior lobe

What are the lobes that the fissures divide the cerebellum into ?

Anterior lobe Posterior lobe Flocculonodular lobe

What are VIII CN 2 special sensory (Sp) components

Auditory/cochlear component Vestibular component

Why is the cerebellum considered part of our motor system?

Because dysfunction in the cerebellum causes changes in movement Not sensory

Mossy Fibers

End on granular cells Less direct route to Purkinje cells mossy --> granule cell --> parallel fiber --> Purkinje cell

Medial hemisphere

Between the vermis and lateral hemisphere Adjust limb movements Interposed Nuclei

Fastigial Nuclei

Bilateral - Vestibular Nuclei Contralateral - Reticular Formation

Superficial to deep

Bony labyrinth Perilymph Membranous labyrinth Endolymph

What do these components do ?

Both divisions have specializations that transduce fluid movement into action potentials

What are the are two special types of fibers responsible for bringing sensory inputs to the cerebellar cortex ?

Climbing fibers Mossy Fibers

Organ of Corti

Cochlear duct

What side does the signal to the thalamus from the cerebellar hemisphere go ?

Contralateral

What are the cerebellar functions ?

Coordinates muscle action Plays a major role in the learning of motor tasks Helps maintain equilibrium Regulate muscle tone & posture Plays a role in cognition

Cerebellum is going to have influence on the ipsilateral motor function

Corticospinal tract that is ipsilateral Motor cortex and thalamus will be on the contralateral side

What is located in the membranous labyrinth ?

Endolymph

Molecular (ML)

Dendrites of the purkinje main site for synapse but not many neurons

What are the deep cerebellar nuclei ?

Dentate Interposed Fastigial

Lateral Cerebellar Hemisphere

Dentate nucleus - PLANNING MOVEMENT Project to the motor and pre motor cortex Light up BEFORE

Bending of stereocilia towards kinocilium causes

Depolarization

In angular acceleration the movement of the endolymph causes what ?

Distortion of the cupular and hair cells Ampullae of the semicircular duct - crista

Climbing Fibers

End on Purkinje cells and wraps around Purkinje dendrites Most powerful EXCITATORY input in the nervous system

The vermis project to what nuclei ?

Fastigial Nuclei

Perilymph

Fills the bony labyrinth

In Linear acceleration the Maculae of the UTRICLE is ____ when the head is upright ?

Horizontal

Bending away from kinocilium causes

Hyperpolarization

What side does the cerebellar hemisphere affect ?

IPSILATERAL

What is the main input that the CLIMBING fibers carry into the cerebellum ?

Inferior olivary nucleus -Contralateral

No direct motor output at all. Why?

Information is processed at a subconscious level

Are purkinje dendrites inhibitory or excitatory ?

Inhibitory to deep cerebellar nuclei

What is the cerebellar pattern ?

Inputs enter the cerebellar cortex --> purkinje inhibitory communication travel to deep cerebellar nuclei --> Exit to targets (thalamus or brainstem)

Medial Cerebellar Hemisphere

Interposed Nucleues -adjusting limb movements Light up DURING

What are the 2 types of hair cells ?

Kinocilium Stereocilia

Purkinje

Large neurons Dendrite tree is big house the only axon that leaves the

Cerebellar Dysfunction lateral Damage

MORE COMMON -cause limb ataxia and changes in muscle tone & reflexes (often decreased), ipsilateral to lesion

Interposed

Medial Hemisphere

Where are the hair cells located ?

Membranous Labyrinth

What is suspended in the bony labyrinth ?

Membranous labyrinth

What are the 3 layers of the Cerebellar Cortex form superficial to deep

Molecular Purkinje Granular

Lateral hemisphere

Most lateral Planning motor movement -motor cortex and pre motor ctx Dentate Nucleus

Dentate

Most lateral nucleus - Lateral hemisphere

Vermis

Most medial Postural adjustments and eye movements Fastigial nuclei

Inferior Cerebellar Peduncle

Mostly afferents from the spinal cord and brainstem

Depolarization is caused by potassium or sodium ?

Potassium

Nystagmus

Named in the direction of the spin

How do inputs and outputs travel to and from the cerebellum?

Peduncles

There Cerebral cortex projects to cerebellum what nuclei ?

Pontine Nuclei

Cerebellar Dysfunction Midline Damage

RARE -postural instability and ataxia of lower extremities

Left hemisphere of the cerebellum is associated with ...

Right motor cortex

Rapid to the L and Slow to the Right after you stop Slow phase opposing eye movements

Right sided Nystagmus

What detects linear acceleration ?

Saccule Utricle

Ampullae

Semicircular duct - crista

Granular (GL)

Send axons to molecular layer Cells will shoot up and difricate into paraelle fibers

The posterolateral fissure separates the ..

Separates the posterior lobe from the Flocculonodular Deep

The horizontal fissure separates the ..

Separates the posterior lobe into two parts

Vestibulocochlear N (CN VIII) Inputs

Sound info and position/movement of the head info Keeping track of body orientation relative to the world

In Linear acceleration the Maculae of the SACCULE is vertical when ?

The head is upright

Cerebellar Dysfunction Gait Pattern

Wide- based, Staggering

Intermediate (medial) or lateral hemispheres affected -->

appendicular ataxia

Cerebellar output goes primarily to ...

brainstem and thalamus

Cupula

gel-like substance surrounding stereocilia & kinocilium Angular acceleration