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How Does the Nervous System Communicate Notes

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How Does the Nervous System Communicate?
- PNS helps CNS communicate with the body
- receives sensory information
- transmits messages to muscles
- Nerves’ Functions
- Sensory Neurons:
- afferent fibers in CNs and SNs
- ascending pathway
- carry information into CNS
- sensory info from PNS sent to cerebral cortex
- Motor Neurons:
- efferent fibers in CNs and SNs
- descending pathway
- carry information away from CNS
- motor signals sent from brain to LMN
Direct and Indirect Motor Systems
- Direct Motor Pathway:
- pyramidal system
- originates in primary motor cortex
- responsible for rapid, volitional movement
- directly controls activation of muscles
- Indirect Motor Pathway:
- extrapyramidal system
- regulates reflexes
- maintains posture and muscle tone
- facilitates movement
→ Direct and Indirect Pathways form the upper motor neuron system
Upper Motor Neurons
- descending/efferent tracts of axons
- originate in cerebral cortex
- travel in CNS
- synapse with LMNs of PNS
- each UMN pathway innervates LMNs on contralateral side
- divided into pyramidal and extrapyramidal tracts
- pyramidal direct activation system
- extrapyramidal indirect activation system
Pyramidal System
- bilateral tracts
- originate in primary motor cortex
- lead directly to CNs & SNs in brainstem/spinal cord
- voluntary control of musculature
- relay intentional movement
Extrapyramidal System

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- tracts originate in cortex of each hemisphere
- multiple connections and pathways
- involuntary and automatic control
- muscle tone, balance, posture, coordination
- relay automatic, involuntary movement
Lower Motor Neurons
- efferent component of CN/SN
- LMNs of CNs serve head and neck muscles
- synapse with UMNs at brainstem
- originate in brainstem and spinal cord
- axons leave CNS (as part of CN or SN)
- and travel to specific muscle
- final common pathway (FCP)
- last link in chain that leads to movement
Motor Speech Control
- primary motor cortex in frontal lobes
- controls execution of movement
- sequences of movement that require activity of multiple muscle groups
- descending pathways
- originate from primary motor cortex
- initiate voluntary motor movements
→ Reminder: sensory and motor functions of the cerebrum are contralateral
Motor Speech Disorders: What are they?
- difficulties related to problems of movement
- result from neurological disorder or injury
- acquired or congenital
- affect:
- motor planning - Programming
- coordination - neuromuscular control
- timing and execution
Dysarthria
- General Description
- group of motor speech disorders
- lesions to different parts of CNS and/or PNS
- affects speech production: speed, range, direction, strength, timing of motor movements
- result of: weakness, spasticity, discoordination, involuntary movements
- Common Characteristics:
- inadequate respiratory drive
- voice disturbances→ pitch and loudness problems
- prosodic abnormalities→ excessive stress
- rate difficulties: slow, rapid, varying speeds
- hypernasality or imprecise articulation
Spastic Dysarthria
- Etiology: Bilateral UMN lesion:

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How Does the Nervous System Communicate? - PNS helps CNS communicate with the body - receives sensory information - transmits messages to muscles - Nerves’ Functions - Sensory Neurons: - afferent fibers in CNs and SNs - ascending pathway - carry information into CNS - sensory info from PNS sent to cerebral cortex - Motor Neurons: - efferent fibers in CNs and SNs - descending pathway - carry information away from CNS - motor signals sent from brain to LMN Direct and Indirect Motor Systems - Direct Motor Pathway: pyramidal system - originates in primary motor cortex - responsible for rapid, volitional movement - directly controls activation of muscles - Indirect Motor Pathway: - extrapyramidal system - regulates reflexes - maintains posture and muscle tone - facilitates movement → Direct and Indirect Pathways form the upper motor neuron system Upper Motor Neurons - descending/efferent ...
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Awesome! Perfect study aid.

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