Cerebellum and Basal Ganglia

Suzanne Stensaas, PhD(David Roman Renner, MD)

2009 Kenya Curriculumrepurposed for Dental Neuroanatomy

2012

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CBLM

Courtesy of Stephen C. Voron, MD

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CBLM

Courtesy of Stephen C. Voron, MD

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CBLM

pyramidalcell in themotorhomunculusof the frontallobe

Courtesy of Stephen C. Voron, MD

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CBLM

corticospinaltract

Courtesy of Stephen C. Voron, MD

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CBLMdecussationat thepyramids(spino-medullaryjunction

Courtesy of Stephen C. Voron, MD

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CBLM

thalamus:AKA the“gate keeper”preventsunwantedmovements

Courtesy of Stephen C. Voron, MD

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CBLM

BASALGANGLIA

consultant onautomaticmovements

providesinput into thethalamus

Courtesy of Stephen C. Voron, MD

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Courtesy of Stephen C. Voron, MD

Cerebellum:

consultant onrapidmovements

providesinput into thethalamus

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CBLM

Basal Ganglia Symptoms

• resting tremor• postural instability• festination• rigidity• masked facies• bradykinesia• dyskinesia• torticollis• chorea• athetosis• hemiballismus• akathisia

Cerebellar Symptoms

• intention tremor• dysmetria• dysdiadochokinesia• hypotonia• heal to shin• finger to nose• rebound• ataxic gait• titubation• nystagmus• dysmetric saccades

Basal ganglia lesions producecontralateral signs.

Cerebellar lesions produceipsilateral signs.

Most movement disorders produced bycerebellar and basal ganglia pathologydisappear during sleep.

Cerebellar and basal ganglia signs areusually not present if the corticospinal tractis damaged.

The cerebellum is the great comparator:

1. It compares cortical willful command with muscle tension, joint position, & tone (via ipsilateral spinocerebellar tracts)

2. Advises the cortex on how much, how many, how fast3. The motor cortex sends the revised command down the corticospinal tract

The BASAL GANGLIA are the autopilotfor procedural movements.

The CEREBELLUM is the refiner offinely controlled movements

(particularly of fingers).

COMPARISON OF MOTOR SYSTEMShttp://library.med.utah.edu/neurologicexam/html/home_exam.html

Lower Motor Neuron

Spinal Cord

Upper Motor Neuron

Corticospinal Tract

Cerebellum Basal Ganglia

Normal

Efferent part of

monosynaptic reflex

Voluntary movement Rapid coordinated alternating

skilled movements that are

learned

Facilitates intentional

movements and inhibit

extraneous movements

Muscle tone by

inhibiting antagonists

Muscle tone Eye-head movements Autopilot for motor activities

Maintains muscle

fibers (trophic factors)

Fine control, espec. finger

flexors

Posture and Gait

Inhibitory to Lower motor

neurons

Balance, equilibrium,

orientation in space

Voluntary movements in an

automatic manor.

Weakness or paralysis Weakness or paralysis timing, duration, and amplitude

Abnormal

Areflexia Hyperreflexia

Hyperactive deep tendon

reflexes

Truncal ataxia, gait ataxi a Shuffling or festinating gait,

small steps, hard to turn

Fasciculation Babinski- extensor plantar

reflex

Nystagmus, Dizziness , Masked facies, few blinks

Muscle Atrophy Spasticity Decomposition of movement Difficulty turning or starting,

hypokinetic = bradykinesia

Flaccid paralysis Dysmetria- ataxia of arms Paucity of associated

movements

Dysynergia

Dysdiadochokinesia- inability

to do rapid alternating

movements

Chorea, athetosis,

hyperkinetic

Hypotonia- pendular reflexes Rigidity ( lead-pipe )

(cogwheel),

Intention tremor Resting tremor

Scanning speech Soft speech

Courtesy of Stephen C. Voron, MD