Flashcards in 12. contributions of cerebellum and basal nuclei to motor function Deck (56)
What are functions of primary motor cortex (area 4)?
1. signal motor neuron to contract skeletal muscle fibers
2. uses corticospinal tract for signaling
3. commands have extensive processing from cerebellum and basal nuclei
What are the functions of premotor cortex (area 6)?
1. plans movements based on sensory and visual cues
What is the function of the supplementary motor area (area 6)?
1. retrieves and coordinates memorized motor sequences
What are the functions of the motor cortex system?
1. provide activating signal to spinal cord
2. issues sequential and parallel commands that initiate carious cord patterns
3. cortical patterns are complex and can be learned
4. cord patterns are hereditary and hard wired
What are key functions of the cerebellum?
1. timing of motor activities in rapid, smooth progression from one muscle movement to the next
2. helps sequence motor activities
3. monitors and makes corrective adjustments to motor activities during execution
What does the vermis separate?
1. divides into intermediate zone and a lateral zone
The cerebellum is divided into three different lobes anatomically. What are they?
1. anterior lobe
2. posterior lobe
3. flocculonodular lobe (associated with vestibular system)
What is the vermis?
1. separates the intermediate zone and lateral zones
2. located for control functions for muscle movement of axial body, neck, shoulders, and hips
What is the intermediate zone?
1. controls muscle contractions in distal portions of upper and lower limbs
What is the lateral zone?
1. associates with cerebral cortex and plans sequential motor movements
What forms the inner layer of gray matter, and what nuclei are contained within that region?
1. intracerebellar nuclei
2. dentate, emboliform, globose, fastigial nuclei pairs
Where would a lesion have to occur to cause extremity ataxia?
1. dentate, emboliform, and globose nuclei
2. these fibers project into red nucleus
3. associate with limb musculature and fine manipulative movements
What would cause trunk ataxia?
1. lesion to fastigial nucleus
What are characteristics of fastigial nuclei?
1. fibers project into reticular formation and vestibular nuclei
2. related to postural activity and limb movements via reticulospinal and vestibulospinal tract
What is the granular layer of the cerebellar cortex?
1. innermost layer of granule cells, golgi type II cells, and glomeruli
2. site where mossy fibers synapse with granular cells and golgi type II cells
What is the purkinje cell layer of the cerebellar cortex?
1. middle layer of purkinje cells
What is the molecular layer of the cerebellar cortex?
1. outermost layer.
2. stellate cells, basket cell, purkinje dendrite, golgi II, axons of granule cells
What are granular cells?
excitatory cells that form parallel fibers in cortex
What are golgi cells?
inhibitory cells that project from parallel fibers to granular cell bodies
What are basket cells?
inhibitory cells that project from parallel fibers to purkinje axon hillock
What are stellate cells?
inhibitory cells that project from parallel fibers to purkinje dendrites
Which cells in the cerebellar cortex provide lateral inhibition on adjacent purkinje cells to provide damping?
basket and stellate cells
What are some characteristics of purkinje cells?
1. only output from cortex and is always inhibitory
2. extensive dendritic branching
3. project to intracerebellar (inhibitory) nuclei
What are cerebellar cortex climbing fibers?
1. orginate in medullary olives
2. condition purkinje cells and provide motor learning
3. multiple synapse with purkinje cells
What are cerebellar cortex mossy fibers?
1. originate from vestibulocerebellar, spinocerebellar, and pontocerebellar tracts
2. multiple synapse on purkinje cells
3. synapse on granule cells in glomeruli
What are the functions of the purkinje cell axons?
1. efferent fibers that regulate rate, range, directoin or movement
2. output is cerebellar cortex
3. GABA neurotransmitter
What happens when mossy fibers enter the cerebellum from numerous sources?
1. excitatory collaterals are sent to deep nuclear cells and synapse in granular layer with thousand of granule cells
2. all originate from inferior olives
What are the regions of the cerebellum that contribute to motor control?
What are characteristics of teh vestibulocerebellum?
1. flocculonodular lobes and vermis
2. control balance and eye movement