Basal Glanglia Flashcards
Basal ganglia structures
Caudate Putamen Globus pallidus Subthalamic nucleus Substantia nigra
Striatum
Caudate and putamen
Lenticular nucleus
Putamen
Globus pallidus
Basal ganglia function
Indirect influence on movement via the thalamus
PIE - planning, initiation, execution of movement
Other basal ganglia functions
Postural control
Maintaining muscle tone
Production of automatic movements
Does the basal ganglia receive sensory input?
No
Basal ganglia - input nuclei
From cortex
Primarily striatum(caudate, putamen)
Also substantia nigra
Basal ganglia - output nuclei
To thalamus
Via the globus pallidus inter us and substantia nigra
Two pathways exist from input to output basal ganglia nuclei
Direct pathway and
Indirect pathway
Direct pathway
net effect: thalamus excitation
Disinhibition
facilitating movement
Increased movement
Indirect pathway
net effect: thalamus inhibition
inhibiting movement
Decreased movement
BG inhibits the thalamus
Input to thalamus is inhibitory via globus pallidus and substantia nigra
Normal BG output at rest
Some amount of inhibition on the thalamus
How much of thalamus is inhibited by GB determines if movement will occur or not
BG and cortex
Cortex contributes to how much the BG inhibits thalamus via the direct and indirect pathways
Thalamus not/less inhibited
Disinhibited = INCREASED movement
Thalamus inhibited
Decreased movement
BG has other than news for different functions
Passes through different pathways and projects to frontal lobe and limbic system
Motor (movement), oculomotor (eye movement), prefrontal (cognitive processes), limbic (emotion and motivational drives- neurobehavioral and psych disorders)
Common movement disorders no/slow movement —> fast
Akinesia Bradykinesia/hypokinesia Rigidity Dystopia Athetosis Chorea Ball is us Tics Myoclonus Tremor
BG and dyskinesia
Abnormal movement caused by BG dysfunction
Akinesia
Bradykinesia
Rigidity
Rigidity
Increased, uniform resistance to passive movement of a limb throughout the entire ROM
Superimposed by rachetlike jerkiness to passive movement of a limb
Movement disorders - involuntary movements
Dystonia (sustained contractions) Athetosis (writhing) Chorea (rapid, irregular,jerky) Ballismus (large amp, sudden flailing) Tics (twitches) Myoclonus (cyclical, spasmodic alteration in contract and relax)
Tremor
Rhythmic or semi-rhythmic oscillation movement
Resting tremor
Often seen w/ BG lesion
Obvious when limbs are at rest, decreases/stop when pt moves limbs
Parkinon’s disease
Idiopathic neurodegenerative condition caused by loss of dopaminergic neurons in substantia nigra
Parkinson’s triad
Bradykinesia, rigidity, resting tremor —>
Postural instability, unsteady gait
Parkinson’s onset, progression
45-65 yo
M>F
Progression is gradual leading to severe disability
Reasons well to LevoDopa
Which pathway more effected w/ Parkinson’s?
Direct pathway
DA normally has excitatory effect on direct ath way and inhibitory effect on indirect
W/ loss of DA—> underactive direct pathway, overactive indirect pathway —> no/less movement
Huntington’s disease
Autosomal dominant neurodegenerative disease
Progressive - usually choreiform movement disorder, along w/ dementia and psych disturbances, ultimately lead to death
Progressive atrophy of caudate nucleus and also putamen
Huntington’s onset
30-50 yo
Initial symptoms: subtle chorea, behavioral disturbances
Death usually occurs w/in 10-15 yr after onset
Huntington’s characterized by
Abnormalities of body movements, emotions, cognition
Tics, athetosis, dystopia posturing
Which pathway more effected - Huntington’s?
Indirect!
Less/no Enk released by striatum
Result is disinhibition of thalamus which produces movement
