(Transcribed from Dr. Glasser’s lecture, 2 June 2000 by Brian Buschman)
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The cerebellum is important for:
1) Programming and coordinating motor behavior.
2) The smooth sequencing of motor programs.
3) Regulating muscle tone.
4) Equilibrium and balance.
Cerebellar dysfunction results in:
1) Reduced reflexes.
2) Decreased muscle tone.
3) Asynergy of affected muscle groups.
a. Dysmetria is the mismeasurement of distance (inability to hit the mark).
b. Rebound phenomena – The failure to adjust to rapid changes in muscle tension.
c. Dysdiadechokinesis is an inability to accurately carryout a rapid series of alternating movements. “Show me how to open a jar.”
4) Intention tremors – Tremors that get worse as you approach the target
5) Axatia – Inability to walk properly, often with a broad-based gate and ataxia of speech. (Like in a drunk)
6) Nestagnus (abnormal) is when the patient has abnormal eye movements while standing still.
The cerebellum is broken up into four lobes. Each lobe has a deep nucli and carries out a specific function out of the roles of the cerebellum.
The floccular lobe is associated with coordination and muscle tone. The two sides of the floccular lobe are joined in the middle by the nodule. The floccular lobe is the one exception in that it does not have an associated deep nucli. The floccular lobe is the most posterior of the cerebellar lobes.
The vermis is the central lobe of the cerebellum and is associated with the fastigial nucleus. It contains the central part of the motor homunculus of the cerebellum which holds the controls for coordination of muscles of the head and trunk (axial muscles). Due to it’s function it is associated with the vestibular nucleus and reticular formation.
The paravermis is the medial of the three adjacent lobes adjoining the vermis. It contains the UL and LL portions of the motor homunculus and in such is associated with the red nucleus and the cerebral cortex. It is associated with the interposed nucleus which is made of the globose and emboliform nucli.
As it’s name implies the lateral lobe is the most lateral of the three adjoining cerebellar lobes. It is associated with the largest of the cerebellar nucli, the denticulate, and functions in coordination of the motor program. In working with motor coordination the denticulate nucleus is directly associated with area 6.
1) The cerebellum does it’s work ipsilaterally.
When the red nucleus is communicating with the paravermis the right red nucleus must cross to talk with the left paravermis and then cross again for the signal to return to the right red nucleus.
2) The cerebellum works via feedback looks involving the UMNs and cerebral cortex.
3) All input to the cerebellum is excitatory.
4) All input to the cerebellum is to the cerebellar cortex and associated deep nucli.
5) All output from the cerebellum is via the deep nucli except for the floccular lobe since it does not have a deep nucli.
6) All output from the cerebellar cortex is onto associated nucli via perkinji cells.
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