Cerebellum and Basal Ganglia

Suzanne Stensaas, PhD (David Roman Renner, MD) 2009 Kenya Curriculum repurposed for Dental Neuroanatomy 2012 BG

CBLM

Courtesy of Stephen C. Voron, MD BG

CBLM

Courtesy of Stephen C. Voron, MD pyramidal cell in the motor homunculus BG of the frontal lobe

CBLM

Courtesy of Stephen C. Voron, MD corticospinal tract

BG

CBLM

Courtesy of Stephen C. Voron, MD BG

CBLM decussation at the pyramids (spino- medullary junction

Courtesy of Stephen C. Voron, MD thalamus: AKA the “gate keeper” prevents unwanted BG movements T

CBLM

Courtesy of Stephen C. Voron, MD BASAL GANGLIA

consultant on BG automatic T movements

provides CBLM input into the thalamus

Courtesy of Stephen C. Voron, MD Cerebellum:

consultant on rapid BG movements

provides input into the CBLM thalamus

Courtesy of Stephen C. Voron, MD Basal Ganglia Symptoms Cerebellar Symptoms

• resting tremor • intention tremor • postural instability • dysmetria • festination • dysdiadochokinesia • rigidity • hypotonia • masked facies • heal to shin • bradykinesia • finger to nose • dyskinesia • rebound • torticollis • ataxic gait • chorea • titubation • athetosis • nystagmus • hemiballismus • dysmetric saccades • akathisia Basal ganglia lesions produce contralateral signs.

Cerebellar lesions produce ipsilateral signs. Most movement disorders produced by cerebellar and basal ganglia pathology disappear during sleep.

Cerebellar and basal ganglia signs are usually not present if the corticospinal tract is 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 fast 3. The motor cortex sends the revised command down the corticospinal tract The BASAL GANGLIA are the autopilot for procedural movements.

The CEREBELLUM is the refiner of finely controlled movements (particularly of fingers). COMPARISON OF MOTOR SYSTEMS http ://library.med.utah.edu/neurologicexam/html/home_exam.html

Lower Motor Neuron Upper Motor Neuron Cerebellum Basal Ganglia Spinal Cord Corticospinal Tract Normal Efferent part of Voluntary movement Rapid coordinated alternating Facilitates intentional monosynaptic reflex skilled movements that are movements and inhibit learned extraneous movements Muscle tone by Muscle tone Eye-head movements Autopilot for motor activities inhibiting antagonists Maintains muscle Fine control, espec. finger Posture and Gait fibers (trophic factors) flexors Inhibitory to Lower motor Balance, equilibrium, Voluntary movements in an neurons orientation in space automatic manor. Weakness or paralysis Weakness or paralysis timing, duration, and amplitude Abnormal Areflexia Hyperreflexia Truncal ataxia, gait ataxia Shuffling or festinating gait, Hyperactive deep tendon small steps, hard to turn reflexes Fasciculation Babinski- extensor plantar Nystagmus, Dizziness, Masked facies, few blinks reflex 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 Chorea, athetosis, to do rapid alternating hyperkinetic movements Hypotonia- pendular reflexes Rigidity ( lead-pipe ) (cogwheel), Intention tremor Resting tremor Scanning speech Soft speech Courtesy of Stephen C. Voron, MD