Cerebellum 2 Flashcards
What are the three regulatory functions of the cerebellum?
- reflex tone of skeletal muscle
- coordination of voluntary muscle activity
- aids in maintaining equilibium
What is the basic function of the cerebellum?
Smoothing and Sequencing of complex movements.
Support postural adjustments and eye movements establishing and modifying motor programs.
The cerebellum functions are attributed to interactions w/
- Ascending Sensory Pathways
- Vision
- Vestibular Fxn
- Cortical plans of movments
The functions of the cerebellum end up providing
- Comparison of internal and external feedback
- Modifying central motor programs.
- Center for motor learning/memory.
What structure in the cerebellum allows for output?
efferents from cerebellum from deep cerebellar nuclei
Where do efferents, neurons from deep cerebellar deep nuclei sweep out to
effect some sort of physiological behavior on target cell = usually excitatory
What are deep cerebellar nuclei under inhibitory control of?
Purkinje Cells
What does purkinje cell control over deep cerebellar nuclei allow for?
Inhibitory control allows for normal patterned movement.
What three lobes is there cerebellum broken up into?
Anterior, Posterior, Flocculonodular
How is the flocculonodular lobe broken up?
Nodule in the midline and Flocculus are lateral.
Where are the cerebellar tonsils located?
What is their structural significance?
Clinical significance?
Posterior edge of cerebellum.
Have structural significance to connections of cerebellum.
Clinically positioned next to foramen magnum and can be forced through pinching medulla with increase of intracranial pressure.
Where is the Vermis located?
Midline.
Where are the deep cerebellar nuclei located?
lie in white matter of cerebellum deep to cortical circuitry.
What are the three deep cerebellar nuclei and what is their associated functional division and anatomical location?
- Fastigial Nucleus - Vestibulocerebellum: receives input from vermis and some floculonodular lobe
- Interposted Nucleus (Globose and Emboliform) - Spinocerebellum: receive input from intermediate part of cerebellar hemispheres
- Dentate Nucleus - Cerebrocerebellum: get projections from lateral cerebellar hemispheres
What are the three layers of the cerebellar cortex?
Molecular Layer
Purkinje Cell Layer
Granular Cell Layer
What is the Molecular Layer made up of?
acellular made of:
axons and dendrites
- unmylenated granule cell axons
- purkinje cell dendrites
- Interneurons
What is the Purkinje cell layer made up of and what is its function?
What does it receive?
Cell bodies of large peukinje cells.
Form output of cerebellar cortex
Fxn: influence activity of deep cerebellar nuclei through INHIBITION
Receives 1 major afferent system (mossy fiber system from granular layer).
What is the granular layer made up of?
What does it receive?
Granular Cells - majority of axons in the molecular layer and synapse on dendrites of the purkinje cells.
Receives most input form afferent systems = mossy fibers
All axons going upward are excitatory/inhibitory and consist of what three fibers?
upward = Excitatory
- Mossy Fibers
- Climbing Fibers
- Granule Cell Parallel Fibers
All axons going downward are excitatory/inhibitory and consist of what fibers?
downward = Inhibitory
1. Purkinje Cells
What is the route of mossy fibers and what do they synapse on?
Ascend through cerebellar white matter (excitatory) synapse onto granule cell dendrites
Where do granule cells send axons?
Granule cells send excitatory parallel fibers to dendritic trees of purkinje cells.
What is all output from cerebellar cortex carried by?
Purkinje cell axons to cerebellar white matter.
Purkinje cells send synapses where?
inhibitory synapses onto deep cerebellar nuclei
Where do climbing fibers arise from and where do they go to?
Arise from neurons in contralateral inferior olivary nucleus and send excitatory input to purkinje cells.
What is the function of the inferior, middle, and superior peduncles?
Connects lower brainstem and forms wall of 4th ventricle.
Superior Peduncle:
Efferent or Afferent?
Pathways?
Only Efferent pathway.
Decussates in the midbrain at the level of inferior colliculus.
- Denatorubrothalamic pathway
- Ventral and Rostral Spinocerebellar Pathway
Ventral and Rostral spinocerebellar pathway: What does it carry and what is its route?
Carries integrated info of sensory and motor from ipsilateral spinal cord.
Pathways cross contralateral at spinal cord segment level, and recross through cerebellar peducle.
Middle Peduncle:
Efferent or Afferent?
Pathways?
Only Afferent pathway
- Massive connections to pons
- Pontocerebellar fibers carrying info relayed through pontine nuclei in ventral pons.
- Relay receives cortical info from all parts of cortex.
Inferior Peduncle:
Efferent or Afferent?
Pathways?
Both Afferent and Efferent
Dorsal and Cuneocerebellar Pathways Olivocerebellar Pathway Trigeminocerebellar Pathways Vestibulocerebellar Pathways Fatigiovestibular Pathway
What information do Dorsal and Cuneocerebellar pathways and from where?
Carry specific joint and motor info encoded by:
- GTOs
- Muscle Spindles
- Jt capsule receptors
Where does info from Olivocerebellar Pathway come from and what fibers does it have?
comes from contralateral inferior olivary complex – climbing fibers
What info does the Trigeminocerebellar Pathway transmit and where from?
carry similar somatosensory info from the
- Face
- Jaw
- Extraocular eye muscles
Vestibulocerebellar pathways carry axons from where (2)?
carry axons from vestibular nuclei and direct fibers from vestibular apparatus
Fastigiovestibular pathways carry what kind of information to where?
carries efferent pathway from fastigial and interposed nuclei –> vestibular nuclei and reticular nuclei
some purkinje cell axons bypass deep cerebellar nucli and project directly to vestibular nuclei
Vestibulocerebellum: Anatomical Cerebellum Input Deep Nuclei Cerebellar Peduncle Output Target
Vestibulocerebellum:
Anatomical Cerebellum: Flocculonodular Lobe
Input: Vestibular Nuclei and apparatus/ganglia
Deep Nuclei: Vestibular Nuclei (fastigial?)
Cerebellar Peduncle: Inferior
Output Target: MLF - eye mvmt pathways
Vestibulocerebellum pathway:
function
ipsilatera/contralateral/bilateral
Sends info back to influence vestibular nuclei fxn and reticulospinal pathways
-ipsilateral
fxn:
- control equilibrium
- eye movments
- trunk and postural muscle tone = proximal
Spinocerebellum: Anatomical Cerebellum Input Deep Nuclei Cerebellar Peduncle Output Target
Spinocerebellum:
Anatomical Cerebellum: Vermis and paravermal zones
Input: General cutaneous and proprioceptive receptors: SC, auditory, visual, vestibular, trigeminal, motor cortex
Deep Nuclei: Interposed Nuclei, Fastigial Nuclei
Cerebellar Peduncle: Superior and Inferior
Output Target: VL, Red Nucleus, Tectum, RF, Vestibular Nuclei
Spinocerebellum:
function
controls limb movments and muscle tone for error correction –> coordinated movments
- muscle synergy
- more proximal limb joints = postural and locomotion
