Term
| The motor system is essential to... |
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Definition
| normal reflexes; maintaining muscle tone & posture; and planning, initiating, & controlling voluntary movements |
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Term
| system components of the motor system |
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Definition
| cortex/efferent connections; basal ganglia; cerebellum, motor nuclei in brainstem (cranial & spinal)/efferent tracts; striated muscle |
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Term
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Definition
| direct motor system; two primary nerve tracts that together form part of the upper motor neuron system. |
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Term
| name the two tracts of the upper motor neuron system |
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Definition
| corticobulbar and corticospinal |
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Term
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Definition
| carries information directly from the cortex to the cranial nerves |
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Term
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Definition
| carries information directly from the cortex to the spinal nerves |
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Term
| what are upper motor neurons? |
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Definition
| neurons controlled by the cortex, cerebellum & basal ganglia that regulate LMNs or final common pathway. |
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Term
| What is the direct connection between the cortex & final common pathway? |
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Definition
| Cortex primarily facilitate finely controlled, discrete movements (through UMN) |
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Term
| ____% of fibers decussate at the medulla |
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Definition
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Term
| UMN in the corticospinal tract innervates... |
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Definition
| LMN on the opposite side of the body |
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Term
| Describe pyramical tract destination of the corticobulbar tract. |
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Definition
| most speech UMNs bilaterally innervate LMNs; technically, many tracts first run through the reticular system before terminating with the actual LMN nuclei |
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Term
| What is the function of the pyramidal tract? |
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Definition
| voluntary motor functions- conciously controlled, skilled, discrete, rapid movements |
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Term
| what are the effects of pyramidal tract lesions? |
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Definition
| loss or reduced skilled movements; usually not as bad at LMN lesions; for corticospinal lesions, weakness on opposite side of the body; reflexes usually not lost. |
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Term
| whatr are the effects of corticobulbar tract lesions? |
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Definition
| effects on speech are minor; some tongue weakness, contralateral lower facial weakness; |
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Term
| unilateral UMN lesions of the corticobulbar tract have what effect on speech? |
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Definition
| very mild speech dysarthria |
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Term
| Bilateral UMN lesions of the corticobulbar tract have what effect on speech? |
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Definition
| spastic dysarthria (very spastic) |
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Term
| What are the components of the indirect motor system? |
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Definition
| corticoreticular tracts, corticorubral tracts, Reticular formation; vestibular nuclei; red nucleus |
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Term
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Definition
| from cortex to reticular formations in the brainstem that intermingle with CS and CB tracts. |
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Term
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Definition
| from cortex to red nucleus --coordinates muscle tone body position and gait. |
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Term
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Definition
| ill-defined neuronal system scattered throughout the brainstem; "seat of consciousness"; mediates ascending sensory information; helps integrate sensory-motor functions; complex effects on LMNs |
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Term
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Definition
| located in the floor of 4th ventricle in Pons and medullar; received sensory information from ear and cerebellum; contribute to muscle tone, esp in spinal and reflex mechanism; role in speech is uncertain |
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Term
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Definition
| found in the brainstem; has both sensory & motor functions; speech role is unclear; has a major role with flexor muslces in the limbs. |
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Term
| What are the functions of the indirect motor system? |
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Definition
| regulates reflexes; helps maintain postures, muscle tone, provides neuromuscular framework for Pyramidal Tract to accomplish skilled discrete actions. |
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Term
| what roll does the indirect motor system play in speech function? |
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Definition
| ensure specific speech movements occur without constant or variable interference with their speed, range & direction. |
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Term
| decorticate posturing of the indirect system |
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Definition
| corticoreticular tracts above midbrain produce increased extensor tone in legs and increased flexor tone in arms. |
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Term
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Definition
| legs extended; resist bending |
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Term
| What is flexor tone in arms? |
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Definition
| arms flexed; resist extension |
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Term
| What is decerebrate posturing? |
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Definition
| lesions below the midbrain produce extensor tone increase in both arms and legs (resist bending) |
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Term
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Definition
| lesions below the medulla or cranial nerves result in loss of all descending input to muscles suppled by spinal system |
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Term
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Definition
| When cortical controls are completely cut of ABOVE BRAINSTEM, reticular formation goes unchecked; extensor muscles become hyperexcited. |
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Term
| UMN lesions of the indrect system affect ... |
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Definition
| both direct & indirect systems; usually spasticity; increased muscle stretch reflexes; direct skilled movements lost; indirect control lost |
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