Cerebellum Flashcards
Cerebellum
Receives inputs of almost all sensory modalities
*** critical role in motor control
Cerebellar organization
Cerebellar cortex is much folded
Spinocerebellum
*** receives proprioceptive & other sensory inputs from all the body parts through spinal cord
receives proprioceptive & other sensory inputs from all the body parts through spinal cord
receives proprioceptive & other sensory inputs from all the body parts through spinal cord
Vermis
Controls posture (axial/proximal limbs)
Paravermis
Skilled voluntary movements
Vestibulocerebellum
Concerned with equilibrium & learning induced changes in vestibulo-ocular reflex
Cerebrocerebellum
Involved in planning & programming of the movements as it interacts with the cortex
Basket Cells
Inhibitory interneurons in the cerebellar cortex whose cell bodies are located within the Purkinje cell layer
Granular Cell Layer
Contains interneurons – granule cells && Golgi cells
Golgi cells
provides inhibitory feedback to the granule cells
Granule cells
receive inputs from mossy fibers
Cerebellar Functions
- Control of postural balance & equilibrium
- Vestibulo-ocular reflex
- Smoothes & coordinates movement
- Control of skilled voluntary movements
- Planning & programming of the movements
Internal Circuitry
- Control of muscle tone & stretch reflex
- Control of movement of one side of body
- Learning & improvement of motor skill
- Eye ball movement
- Vestibular functions
Lesion of flocculonodular lobe
Abnormalities in maintaining equilibrium (motion sickness)
Cerebellum Disorders
*** hypotonia
Inability to carry out long-term adjustment in motor response
Defect in vestibulo-ocular reflex leads to pathological nystagmus
Charcot’s neurologic triad
Nystagmus
intention tremor
scanning speech
disseminated sclerosis
Friedreich’s ataxia
causes progressive damage to the nervous system
resulting in symptoms ranging from gait disturbance to speech problems
Cerebellar Ataxia
Defect in coordination due to errors in the rate, range, force, & direction of movement
- only cerebellar cortex is involved, ataxia is temporary.
- If the lesion involves deep cerebellar nuclei, ataxia is permanent
Cerebellar Ataxia Features
- Drunken gait
- Scanning speech
- Dysmetria
- Intention tremor
- Rebound phenomenon
- Adiadochokinesia (Dysdiadokinesia)
- Decomposition of movement
Anterior vermis syndrome
Involves the lower limb region of the anterior lobe
atrophy of the rostral vermis—most commonly caused by alcohol abuse
Results in gait, trunk, and leg dystaxia
Posterior vermis syndrome
Involves the flocculonodular lobe
Usually the result of brain tumors in children
Most frequently caused by medulloblastomas or ependymomas
Results in truncal dystaxia
Hemispheric syndrome
Usually involves one cerebellar hemisphere
Frequently the result of a brain tumor or an abscess
Results in arm, leg, trunk, and gait dystaxia
Results in cerebellar signs that are ipsilateral to the lesion
Romberg’s test
tests proprioception, vestibular function, and vision
not a test of cerebellar function
Romberg’s test is positive if
the patient sways or falls while the patient’s eyes are closed
