Extrapyramidal Motor System

Question 0

Medium Spiny neurons

Answer 0

Neurons in the neostriatum that utilize GABA

Question 1

Extrapyramidal Motor System

Answer 1

Plays a role in habitual learning and modulating movement

*Actions are unconscious

Question 2

Aspiny Neurons

Answer 2

Interneurons found in the neostriatum that are excitatory and utilize Ach

Question 3

Globus Pallidus

Answer 3

Derived from the diencephalon

*GPi=major output division

Question 4

Afferent projections of neostriatum

Answer 4

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

Question 5

Efferent projections of Neostriatum

Answer 5

1. Globus pallidus
2. Substantia Nigra

(Uses GABA)

Question 6

GP and SN projections

Answer 6

VA/VL

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

Question 7

“Direct” Pathway

Answer 7

Normal projection of Extrapyramidal System

*Dopamine= EXCITATORY

Question 8

“Indirect Pathway”

Answer 8

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

*Dopaimine= INHIBITORY

Net result= Increased inhibition of VA/VL

Question 9

Substantia Nigra projections

Answer 9

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

Question 10

Parkinson’s Disease

Answer 10

*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

Question 11

Lewy Bodies

Answer 11

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

*Synuclein= major component caused by point mutation

Question 12

Parkinsonism due to known insult

Answer 12

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

Question 13

Huntington’s Chorea

Answer 13

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

Question 14

Ballismus

Answer 14

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

Question 15

Dystonia

Answer 15

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

Question 16

Blepharospasm

Answer 16

Abnormal activation of orbicularis oculi

Question 17

Spasmodic dysphonia

Answer 17

Abnormal activation of vocal apparatus

Question 18

Chorea

Answer 18

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

Question 19

Lewy Body Disease

Answer 19

Dementia followed by Parkinsonian characteristics