Descending Motor Pathways Flashcards

1
Q

Describe the location of the motor cortex and name its three sub areas

A

Located anterior to central cortical sulcus. 3 sub areas; Primary motor cortex, premotor area and supplementary motor area and some specialised areas within them.

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2
Q

Describe some features of the primary motor cortex

A

-Topographical representation - Half or the cortex controls hands and muscles of speech - Excitation results in pattern of muscle movement

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3
Q

Describe some of the features of the premotor area

A

-It has similar topographical representation as primary motor cortex - Nerve signals give rise to more complex patterns of movement

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4
Q

Describe some features of the Supplemental motor area

A
  • Contractions elicited are often bilateral (using both hands) - Usually functions together with premotor area (gives background movement)
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5
Q

Describe some features of the corticospinal tract (what it does, travel of neurons)

A
  • Carries signals from cortex to spinal cord - Neurons travel from cortex to pyramids of medulla and the majority cross in lower medulla. They then travel in lateral corticospinal tracts before terminating on interneurons. - Those neurons that do not cross travel in ventral corticospinal tracts
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6
Q

Describe the features of the lateral pathways

A
  • controlled via cerebral cortex via 2 corticospinal tracts - General control of voluntary movement - Mainly associated with control of distal muscles
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7
Q

Describe some of the features of the ventomedial pathway (where ventral corticospinal pathway is found)

A

-Controlled in brainstem - Control of posture and rhythmic movements associated with locomotion - Control of axial and proximal muscles

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8
Q

What are the extra pyramidal tracts and their features?

A

Reticulopsoinal tract - Posture, locomotion and autonomic function Vestibulospinal tract - Balance and posture Rubrospinal tract - From red nucleus and excitatory to flexors Tectospinal tract - head and neck movement for visual tracking.

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9
Q

Posture is adjusted by? and controlled by?

A

Involuntary movement driven by both predicatively (postural set) and reactively (compensation). It is controlled and driven by brainstem

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10
Q

To maintain posture sensory information is integrated from what?

A
  • Muscle proprioceptors (changes in length or tension) - Sense of balance derived from movements of head relative to earths gravitational feild. - Visual inputs
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11
Q

What are the different nuclei within the brainstem?

A

Pontine and medullary (mainly counteract each other) and the vestibular nuclei

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12
Q

Describe some of the features of pontine reticular system

A
  • Nuclei transmit excitatory signals down into the cord via pontine reticulospinal tract in anterior column. - Sends high degreee of excitatory signals to extensor muscles and axial muscles
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13
Q

Describe some of the features of the medullary reticular system

A
  • Nuclei transmit inhibitory signals to same anterior motor neurons via medullay reticulospinal tract in lateral column. - Receives strong inputs from corticospinal tract, rubrospinal tract and other motor pathways.
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14
Q

Describe some of the features of the vestibular nuclei

A
  • Function in association with poutine reticular nuceli to control antigravity muscles - Transmit excitatory signals to antigravity muscles via lateral and medial vestibulospinal tracts
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15
Q

What are Upper motor neurons and Lower motor neurons

A

UMN - Originate in cortex and brainstem nuclei, do not contact muscle LMN - Found in brainstem and spinal cord, motor control to muscles

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16
Q

Describe the features of upper motor neuron lesions

A

Increased tone, spasticity, increased deep tendon reflexes and clonus (repeated rhythmic contraction)

17
Q

Describe the features of lower motor neurons

A

Flaccid paralysis, decreased tendon reflexes, fasciculations and atrophy

18
Q

Draw out the spinal cord tracts

A