Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
26 Cards in this Set
- Front
- Back
|
What structures are considered part of the basal ganglia?
|
Striatum
Globus Pallidus N. accumbens Substantia nigra Subthalamic nucleus |
|
|
To where do the basal ganglia project?
|
VL Thalamus (pars oralis), then to the SMA & PMA
|
|
|
Where in the substantial nigra are dopaminergic cells found?
|
pars compacta
|
|
|
When neurons of the pars compacta are lost, what disease manifests?
|
Parkinsons
|
|
|
Describe the direct loop pathway through the basal ganglia and its net effect
|
Cortex --> Striatum --> Globus pallidus pars interna --> Thalamus --> Cortex
Net effect: excites the thalamus and cortex |
|
|
Describe the indirect loop through the basal ganglia and its net effect
|
Cortex --> Striatum --> Globus Pallidus par externa --> Subthalamic n. --> Globus Pallidus par interna --> Thalamus --> Cortex
Net effect: Inhibition of the thalamus and cortex |
|
|
How is the balance between the direct and indirect loops (excitation and inhibition of thalamus cortex) mediated?
|
Dopamine via substantia nigra pars compacta
|
|
|
What clinical signs are evident after damage to the basal ganglia and what are they categorized as by neurologist?
|
Dystonia *without hyperreflexia*
Dyskinesia Parkinsons "Extrapyramidal Signs" |
|
|
What causes Parkinson's Disease?
|
Loss of dopaminergic projection from the substantia nigra to the striatum
|
|
|
How does Parkinson's disease present clinically?
|
Hypokinesia
Bradykinesia Cogwheel rigidity Resting/Pill-rolling tremor |
|
|
What affect does loss of dopamine have on the loop pathways through the basal ganglia?
|
Produces a net tonic inhibition of the cortex
|
|
|
How is Parkinson's disease most commonly treated?
|
Pts are given both L-DOPA and carbidopa
|
|
|
Why is L-DOPA given instead of dopamine?
|
Dopamine cannot cross the blood-brain barrier, but L-DOPA, its precursor, can
|
|
|
Why is carbidopa given along with L-DOPA?
|
Carbidopa inhibits dopamine decarboxylase in the periphery, thus preventing the conversion of L-DOPA to dopamine before it is able to cross the blood-brain barrier
|
|
|
What surgical procedures have been shown to improve Parkinson's disease and why?
|
Destruction to section of the Globus Pallidus pars interna, which normally inhibits the thalamus & cortex
Therefore, in a condition in which the cortex is tonically inhibited, damaging the GPi will allow cortical activation |
|
|
Define athetosis
|
Slow, twisting, writhing movements of the limbs and trunk
*slower than chorea Often combined with chorea to be called "choreathetosis" |
|
|
Define ballism
|
A type of dyskinesia
Large amplitude, flailing movements of the limbs |
|
|
What causes ballism?
|
Damage to the subthalamic nucleus (cortex is less inhibited)
|
|
|
Define chorea
|
Dancing movements exhibited in Huntingtons
|
|
|
What is the classic presentation of akinesia in Parkinsons pts?
|
Masked face
|
|
|
What is Dystonia musculorum deformans?
|
Rare, hereditary, generalized dystonia
Now called "primary idiopathic torsion dystonia" |
|
|
Define dyskinesia
|
abnormal, involuntary movements
|
|
|
Define dystonia
|
abnormalities of tone, posture, and position
|
|
|
Name the various dyskinesias
|
Akinesia
Bradykinesia, Tremor Chorea Athetosis Ballism |
|
|
Name the various dystonias
|
Rigidity
Torticollis Dystonia musculorum deformans |
|
|
Describe the expected reflexes of a person with a basal ganglia disease
|
No hyperreflexia should be observed, as this is a pyramidal tract sign
|
