Neuro - Mod 5 Motor System

Front 1

the major structures of the CNS involved in motor systems

Back 1

_ Motor cortices
_ Basal ganglia
_ Cerebellum

Front 2

the major structures of the PNS involved in motor systems

Back 2

_ Cranial nerves
_ Spinal nerves for respiration

Front 3

Primary Motor #? Brodmann’s CNS and where?

Back 3

4
Located in the Precentral gyrus - Frontal lobe, bound by the central sulcus and precentral sulcus

Front 4

motor homunculus

Back 4

This disproportionate map of the body in the motor cortex is called the

Front 5

Speech and voice muscles are controlled by the ____ ___ of the primary motor cortex

Back 5

lower 1/3

Front 6

inversely arranged

Back 6

Homunculus

Front 7

The Primary motor Cortex

Back 7

Receives planned motor impulses from cortical and subcortical structures, sends these to the brain stem and the spinal cord

Front 8

Premotor and Supplementary Areas - what do they do?

Back 8

influence movement and all connected to the Primary Motor cortex via these reciprocal connections; also reciprocally connected with the same motor areas on the contralateral hemisphere.

Front 9

The Primary motor Cortex bilateral or unilateral activated?

Back 9

Bilateral activation/innervatin

Front 10

The Primary motor Cortex is mostly uni or contralateral?

Back 10

Mostly contralateral

Front 11

Lesion to this area - may disrupt the initiation of speech

Back 11

Premotor area

Front 12

what does the Basal Ganglia do–

Back 12

Refinement of voluntary motor movement before info transmitted to brain stem and
spinal cord

• Deep structure of clustered nuclei
• produces Dopamine, lesion to this area causes Parkinson’s
• modify our motor movements that are originated in the motor cortex
• regulate muscle tone
• Regulate ongoing movements - make adjustments to automatic movement (arms swinging while walking) and certain facial expressions;
• suppress UNWANTED movement (Inhibits extraneous motor activity)
• involved in motor learning, movements eventually become automatic - (shoot a basketball)
• First learned at the motor cortex and then regulated by the basal ganglia

Front 13

Basal Ganglia works by receiving motor information from the ??????; it modifies this information and then sends it back to the ??? so that the neural signal that eventually gets to the muscles has been smoothed/refined or regulated in the basal ganglia.

Back 13

PMC and associated areas
PMC

Front 14

Through these loops the Basal Ganglia accomplishes its function by

Back 14

influencing of muscle tone, adjustment to movement and the inhibition of unwanted movement.

Front 15

Neurophysiological consequence with Basal Ganglia:
_ Loss of inhibitory control over motor behaviors (disinhibition)

Back 15

Dyskinesia – impaired movement
_ Bradykinesia – slow movement
_ Hypokinesia – reduced range of movement
_ Postural abnormalities
_ Altered muscle tone – rigidity

Front 16

Cerebellar function

Back 16

_ Muscle synergy (ongoing monitoring of muscles)
– Coordination of muscle groups
– Smoothness in movement of muscle groops
_ Muscle tone
_ Range of movement
_ Strength of movement
_ Equilibrium – connects with vestibular system

Front 17

– But when lesioned does not result in paralysis

Back 17

cerebellum

Front 18

Cerebellum Innervation

Back 18

_ Primarily unilateral to input source & output destination.
_ Cerebellar lesions result in ipsilateral symptoms.

Front 19

_ Cerebrocerebellum

Back 19

– Connections to cortex via brainstem & thalamus
• _ For coordination & smoothing (synergy)
• _ Posterior lobe

Front 20

Spinocerebellum

Back 20

– Connections to brainstem & spinal cord
• _ For modifications in muscle tone
• _ Anterior lobe

Front 21

_ Vestibulocerebellum

Back 21

– Connections to vestibular system
• _ Reflexive equilibrium & balance
• _ Flocculonodular lobe

Front 22

Cerebellar Dysfunction

Back 22

ataxia
Tremor

Front 23

tremor

Back 23

_ Action (intention)
• _ Occurs during movement
_ Terminal
• _ Increases in frequency (gets worse) as limb approaches target.
_ Postural
• _ When limb is held against gravity

Front 24

ataxia - cerebellar dysfunction

Back 24

– Dyscoordinated muscle activity
– Causes
_ Hereditary (genetic)
– Autosomal recessive – e.g., Friedrich’s Ataxia
– Autosomal dominant – e.g., spinocerebellar Ataxia
_ Acquired (e.g., tumor, stroke, head-injury)
– Symptoms
_ Slurred speech (ataxic dysarthria)
_ Difficulty walking (feet placed farther apart for balance)
_ Disruption of fine motor control (hand/eye coordination, writing, eating, swallowing) – clumsy
_ Hypotonia

Front 25

UMN

Back 25

all the corticospinal and corticobulbar tracts, contained within the CNS

Front 26

LMN

Back 26

motor neurons in the cranial and spinal nerves; second order neurons; final common pathway

Front 27

describe the UMN and LMN pathway

Back 27

After the motor areas within the cortexes interact with the basal ganglia and the cerebellum; then the upper motor neurons send the appropriate instruction (motor plan) to the motor nuclei within the brain stem and spinal cord (still UPN), then they synapse with the cranial motor nerves in the brain stem, then at that point the transmission becomes the LMN, or final common pathway, then in turn the LMN and the muscle cells equal a motor unit.

Front 28

LMN + group of muscle fiber =

Back 28

motor unit

Front 29

– Spastic paralysis (bilateral lesion)
– Spastic dysarthria (bilateral lesion)
- Apraxia (unilateral damage)
– Hypertonia
– Hyperreflexia
– Clonus
– Babinski sign
– Little/no atrophy
– Diminished abdominal reflexes

Back 29

UMN damage

Front 30

– Flaccid paralysis
– Hypotonia
– Hyporeflexia
– Atrophy
– Fasciculations
– Normal abdominal reflexes

Back 30

LMN damage

Front 31

Innervations Ratio: number of muscle fibers per axon

What does this mean?

Back 31

The lower the Innervation ratio; the finer the movement.
Example 500:1 ratio in the limbs; gross motor
Larynx 25:1 – fine motor
The higher the Innervation ratio; the bigger/gross movement

Front 32

Pyramidal Pathway (UMN) AKA Direct Pathway

Back 32

Corticobulbar and Corticospinal

Front 33

Corticobulbar

Back 33

(corticonuclear) –cortex to brain stem

Front 34

Corticospinal

Back 34

– cortex to spinal cord

Front 35

• Will synapse with cell bodies of cranial nerves
• Represent 70% of all motor fibers

Back 35

Corticobulbar

Front 36

Will synapse with inter-neurons, which will then synapse with cell bodies of the spinal nerves
90% of the these fibers cross/decussates at medulla oblongata – contralateral control
Remaining 10% are ipsilateral forming the anterior this tract
Represent 30% of all motor fibers

Back 36

Corticospinal

Front 37

Involuntary Pathways (LMN) AKA Final Common Pathway

Back 37

_ Extrapyramidal Pathway
_ Autonomic Nervous System
_ Reflex Loops
_diverge from the Corticobulbar and the Corticospinal tracts

Front 38

Damage to the pyramidal tract effects ? and ?.

Damage to the Extrapyramidal tract effects the ? and ?.

Back 38

weakness and paralysis

tone and reflexes

Front 39

Sensory System Example: The Visual System

Back 39

_ First Order – the eye
• _ Light _ retina _ rods and cones convert to chemical response
_ Second Order – the optic nerve
• _ Half of retina crosses midline at optic chiasm and half remains ipsilateral
_ Third Order Neuron
• _ Lateral geniculate body in the thalamus
• _ From here, information transmitted to the primary visual cortex and association areas to the brain to act upon/respond

Front 40

Sensory System Example: The Auditory System

Back 40

1st Order
_ Organ - (the ear as transducer)
• _ External – collects sound
• _ Middle ear – impedance matching, air-fluid interface, changed to mechanical energy
• _ Inner ear – cochlea converts fluid vibrations to neural
2nd ORDER
_ Neural Pathways –
• VIII Acoustic Nerve
3rd ORDER
_ Cerebral Cortex-
• _ primary auditory cortex and temporal association
cortex

Front 41

Tracts of extrapyramidal

Back 41

Extrapyramidal Pathways include:
_ Basal Ganglia Loops
_ Reticulospinal tract
_ Tectospinal tract
_ Rubrospinal tract
_ Vestibulospinal tract