Lecture 19: Cerebellum Flashcards
Some functions of the cerebellum
- Correction of future movements
- Coordinating willed movements
- Motor learning
- No role in conciousness
How does the cerebellum improve volitional movements?
Uses musculoskeletal proprioceptors to tell where limbs are; does calculations and tells cerebrum how to better do the action
Most obvious signs of cerebellar dysfunction
- Unsteadiness of volitional movement
- Unsteadiness of sustained volitional posture
Three lobes of the cerebellum
- Anterior
- Posterior
- Flocculonodular
Longitudinal parts of the cerebellum
- Left Hemisphere
- Right Hemisphere
- Midline vermis
What part of the embryonic brain does the cerebellum come from?
Metencephalon
What does the flocculonodular lobe do in the cerebellum?
Constitutes the vestibulocerebellum; process movements of the head in releation to gravity
Place the cerebellar lobes in order by evolution time
- Flocculonodular
- Anterior
- Posterior
What does the anterior lobe of the cerebellum do?
Processes proprioceptive info from the limbs and trunk
Name the peduncles of the cerebellum
- Superior
- Middle
- Inferior
Types of fibers in the middle cerebellar peduncle
Axons heading from basilar pons to cerebellum crossing the midline
Info from contra motor cortex
What kinds of fibers are found in the inferior cerebellar peduncle?
Inputs from spinocerebellar, trigeminocerebellar, inferior olive, and vestibular nerves
Outputs to tectospinal, vestibulospinal, and reticulospinal
What kinds of fibers does the superior cerebellar peduncle have?
Outputs from deep cerebellar nuclei across the brain to red nucleus, VA/VL in thalamus. These then go to pre-motor and motor cortex.
Primary output peduncle!
Two types of afferent fibers to cerebellum
- Mossy
- Climbing
Major output cells of the cerebellum
- Deep cerebellar nuclei
- Dentate, interposed, and fastigial
Purkinge cells of the cerebellum
Affected by both mossy and climbing fibers directly or indirectly via granule cells
Where do mossy fibers arise from?
- Spinocerebellar fibers
- Pontocerebellar fibers
- Vestibulocerebellar system
What mossy fibers enter the inferior peduncle?
Spinocerebellar, vestibulocerebellar
What mossy fibers enter the middle peduncle?
Pontocerebellar
Where do climbing fibers arise from and go to?
Come from inferior olive via inferior peduncle
What side of the body does the cerebellum deal with?
Ipsilateral
What side of the body does the motor cortex deal with?
Contralateral
UMNs in left motor cortex synapse where?
LEFT basilar pontine gray
Where does a signal from the left motor cortex cross to the right side of the body?
Left pontine cells send axons across via middle cerebellar peduncle as mossy fibers
How do muscles communicate their status to the cerebellum?
Proprioceptors send info to ipsilateral cerebellum via dorsal spinocerebellar tract and inferior cerebellar peduncle as mossy fibers
Know the cerebellar pathways (picture)
What three arteries supply the cerebellum?
- Superior cerebellar artery
- Anterior inferior cerebellar artery
- Posterior inferior cerebellar artery
Infarts of what artery cause Wallenberg’s or Lateral medullary syndrom?
Posterior inferior cerebellar artery (PICA)
Intention tremor
Tremor at the end of a purposeful movement
Four major cerebellar signs
- Ataxia (Decreased coordination)
- Tremor (Intention and postural)
- Hypotonia (Reduced muscle tone)
- Asthenia (Decreased muscle length)
Titubation
Low frequency tremor of head and trunk around 3 Hz
Other names for intention tremor
- End-point tremor
- Kinetic tremor
Nystagmus
Uncoordinated oscillations of the eye
Scanning speech
Voice varies from low to high volume; wrong syllables are stressed
Clinical test for dystaxia of gait
Tandem (tightrope) walking
Dysmetria
Cerebellar patient will often over- or undershoot muscle movement, like when trying to touch their nose
