Extrapyramidal Motor System Flashcards

0
Q

Medium Spiny neurons

A

Neurons in the neostriatum that utilize GABA

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1
Q

Extrapyramidal Motor System

A

Plays a role in habitual learning and modulating movement

*Actions are unconscious

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2
Q

Aspiny Neurons

A

Interneurons found in the neostriatum that are excitatory and utilize Ach

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3
Q

Globus Pallidus

A

Derived from the diencephalon

*GPi=major output division

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4
Q

Afferent projections of neostriatum

A
  1. Cortex (via IC)
  2. Thalamus
  3. Substantia Nigra (uses dopamine)
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5
Q

Efferent projections of Neostriatum

A
  1. Globus pallidus
  2. Substantia Nigra

(Uses GABA)

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6
Q

GP and SN projections

A

VA/VL

-These axons then project to the motor cortex to modulate the firing of neurons in the corticospinal tract

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7
Q

“Direct” Pathway

A

Normal projection of Extrapyramidal System

*Dopamine= EXCITATORY

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8
Q

“Indirect Pathway”

A

Neostriatum projects to GPe, then to subthalamic nuclei, before reaching GPi

*Dopaimine= INHIBITORY

Net result= Increased inhibition of VA/VL

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9
Q

Substantia Nigra projections

A
  1. Red Nucleus
    - muscle tone
  2. Superior Colliculus
    - Adjusts eyes to
  3. Reticular Formation
    - Turns attention to
  4. VA/VL- influence cortex firing of UMNS
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10
Q

Parkinson’s Disease

A

*Mostly idiopathic cause

Loss of pars compacta => loss of dopaminergic input to neostriatum

  1. Increased activity of indirect pathway; decreased of direct
Symptoms include:   "TRAP"
Akinesia
Parkinsonian Stare
Festinating gait
Dyskinesia
Resting tremor
Cogwheel rigidity of muscles
Drooling, increased sebaceous secretion

*Pt will have normal reflexes when startled

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11
Q

Lewy Bodies

A

Inclusion bodies found in the SN in pts. w/ Parkinson’s Disease

*Synuclein= major component caused by point mutation

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12
Q

Parkinsonism due to known insult

A
  1. Encephalitic inflammation
  2. Stroke of ACA, MCA, or PCA
  3. CO Poisoning
  4. Toxic substances
  5. Toxic manifestation of Thorazine/ long-term methamphetamine use
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13
Q

Huntington’s Chorea

A

Abnormal expansion in length of CAG sequence on chromosome 4

=>degeneration of medium spiny neurons (Neostriatum); excess activation of GPe

Overall decreased inhibitory input to VA/VL

Symptoms:
Degeneration of Prefrontal Cortex
Chorea
   -especially of face, tongue, and extremities; pt. may try to hide these
Paranoia

*Highest suicide rate for neurological illness

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14
Q

Ballismus

A

Severe movement disorder including flinging of extremities; fatal disorder within 12 months

-Caused by lesion in subthalamic nucleus
=>Decreased inhibitory input to VA/VL

*Movements will disappear during sleep

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15
Q

Dystonia

A

Abnormalities of lentiform nucleus; possibly due to tumor

-Abnormal posturing of trunk caused by constant contraction of muscles

Symptoms:
Muscle hypertrophy
Torticollis
Blepharospasm
Spasmodic dysphonia
Writer's Cramp
16
Q

Blepharospasm

A

Abnormal activation of orbicularis oculi

17
Q

Spasmodic dysphonia

A

Abnormal activation of vocal apparatus

18
Q

Chorea

A

Motor disturbance characterized by non-rhythmic, continuous involuntary movements especially of the face, tongue, and extremities

19
Q

Lewy Body Disease

A

Dementia followed by Parkinsonian characteristics