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