Contributions of Cerebellum and Basal Nuclei to Motor Function Flashcards
Describe the Primary motor cortex
Signals motor neurons to contract skeletal muscle fibers
Signals via the corticospinal (pyramidal) tract
Execution of commands is preceded by extensive processing by cerebellum and basal nuclei
What are the motor control centers of the cerebral cortex?
Primary motor cortex (Area 4)
Premotor cortex (Area 6)
Supplementary motor area (Area 6)
Describe the premotor cortex
Plans movements based on sensory and visual cues
Describe supplementary motor area
Retrieves and coordinates memorized motor sequences
What are the functions of the motor cortex system?
- provides most of activating signals to spinal cord
- issues sequential and parallel commands that initiate various cord patterns
- cortical patterns are usually complex and can be learned
- cord patterns are mainly determined by heredity and are “hard wired”
What does the cerebellum play major roles in?
The timing of motor activities and in rapid, smooth progression from one muscle movement to the next
What is not essential for locomotion,
helps sequence motor activities,
monitors and makes corrective adjustments to motor activities while they are being executed,
compares actual movements with intended movements,
aids cortex in planning next sequential movement,
and learns by its mistakes?
Cerebellum
What functions with spinal cord to enhance the stretch reflex
functions with brain stem to make postural movements
and functions with cerebral cortex to provide accessory motor functions?
Cerebellum
What turns on antagonist at appropriate time
Helps program muscle contraction in advance
and functions mainly when muscle movements have to be rapid?
Cerebellum
What helps to plan and control complex patterns of muscle movement, controlling relative intensities of the separate movements, directions of movements and sequencing of multiple successive and parallel movements?
Basal nuclei
What plans and executes motor commands in concert with cerebral cortex; and helps cortex execute subconscious but learned pattern?
Basal nuclei
What helps plan multiple parallel sequential patterns?
basal nuclei
What controls complex patterns of motor activity?
Basal nuclei
What does not cause any conscious sensation and rarely causes any motor movement?
Electrical excitation of the cerebellum
Removal of what causes body movements to become highly abnormal?
Removal of the cerebellum
The two hemispheres of the cerebellum are separated by:
vermis
What is each hemisphere of the cerebellum divided into?
An intermediate zone and a lateral zone
The cerebellum is anatomically divided into how many lobes?
3
What are the three lobes of the cerebellum?
Anterior, posterior, and flocculonodular lobe
What lobe of the cerebellum is associated with vestibular system?
Flocculonodular lobe
What is the location for control functions for muscle movements of the axial body, neck, shoulder, and hips?
Vermis
What is concerned with controlling muscle contractions in the distal portions of the upper and lower limbs, esp. hands, feet, fingers, and toes?
Intermediate zone
What is associated with cerebral cortex with planning of sequential motor movements?
Lateral zone
The cortex of the grey matter of cerebellum consists of what?
transversely arranged narrow gyri called folia
Each cortex of the grey matter of cerebellum has what intracerebellar nuclei?
Dentate
Emboliform
Globose
Fastigial
Lesions in which nuclei will cause extremity ataxia?
Dentate, emboliform and globose nuclei
Fibers of which intracerebellar nuclei project to the red nucleus?
Dentate, emboliform and globose
Which intracerebellar nuclei are related to limb musculature and fine manipulative movement?
Dentat, emboliform and globose
Lesion in what intracerebellar nuclei will lead to trunk ataxia?
Fastigial nuclei
Fibers of what intracerebellar nuclei project to reticular formation and vestibular nuclei?
Fastigial nuclei
What intracerebellar nuclei are related to postural activity and limb movements via reticulospinal and vestibulospinal tracts?
Fastigial nuclei
What are the cells in cerebellar cortex?
Granular, golgi, basket, and stellate cells
Which cells in the cerebellar cortex project from parallel fibers to granular cell bodies (-)?
Golgi cells
Which cells in the cerebellar cortex have axons that form parallel fibers in the cortex (+)?
Granular cells
Which cells in the cerebellar cortex project from parallel fibers to purkinje axon hillock (-)?
Basket cells
Which cells in the cerebellar cortex project from parallel fibers to purkinje dendrites (-)?
Stellate cells
Which cells in the cerebellar cortex provides lateral inhibition on adjacent purkinje cells to provide damping?
Basket cells and stellate cells
Which cells in the cerebellar cortex have extensive dendritic branching, receive input from parallel fibers (20k synapses), project to intracerebellar nuclei (-), and are the ONLY output from cortex?
Purkinje cells
Which cells in the cerebellar cortex are the ONLY output from cortex?
Purkinje cells
How many functional units are in the cerebellar cortex?
30 million
What is each functional unit of cerebellar cortex centered on?
A purkinje cell and a corresponding deep nuclear cell
Output from a functional unit is from what?
A deep nuclear cell
Afferent inputs to the cerebellum are mainly from what?
The climbing fibers and the mossy fibers
Where do all climbing fibers originate from?
The inferior olives
Mossy fibers enter cerebellum from a variety of sources and send excitatory collaterals to ___ ___ ___ and then synapse in ____ layers with thousands of _____ _____.
Deep nuclear cells
Granular
Granule cells
Granule cells send axons to _____ _____ ______
Outer cerebellar surface
Granule cell axons branch in ____ directions parallel to folia
Two