Basal ganglia Flashcards
بسم الله الرحمن الرحيم وبه نستعين
Basal ganglia
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Subcortical collection of grey matter nuclei
Deep to cerberal cortex lateral to thalamus
Formed of
Corpus Striatum : Caudate + lentiform ( Putamen + Gllobius pallidus )
Amygdaloid body +
Clastrum+
Functionally related:
Sunthalamic nuclei
SubstaniaNigra
Basal gangilia some characteristics:
-Has no role in sensory function.
-Connected to ipsilateral motor cortex.
-Contralateral Muscle control
-Has no direct contact to spinal cord
lesion = no parylsis.
-Promotes and inhibits motor activity .
describe nervous connections to basal gagnlia ?
-Interconnection for Regulation of intrinsic activity
-basal ganalia Outflow tracts to brainstem then to spinal cord in Extrapyramidals for adjusting muscle tone and posture
-Cortical connections for
Inhibits area 4 , 6 activity
inform B.G About intention to do movments .
Describe loops due to cortical connection to basal ganglia
Caudate + putamen loops circuits
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caudate:-
From Motor and sensory motor areas to the caudate to gllobius palliudus to thalamus to Premotor + supplemetnal + prefrontal for = Cogintve control of sequence motor pattern
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Putamen loops:-
From premotor and supplementory and somatosensory areas to the putamen to gllobius palliuds to thalamus to Premotor and Primary motor area TO eXCUTE Learned Motor patterns
Mention neurotrasnimtters of basal ganglia
Excitatory glutamete in corticoStriate fibers
Inhibitory dopamine in Nigrastratal
Inhibitory gaba in Striato-Nigra + Striatopallidal fibers
Ach excitatory interstriatal
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Must be a balance between dopamin and Ach
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nORadrenaline from B.G To brainstem
Encapleni
serotnin
Functions of basal ganglia circuits
Stimulatory facilitate mucsles activity at the intiation of movments
Inhibitory: inhibits the activity of antagonist + inhibit muscle tone at rest
Describe direct pathway of Basal ganglia
It is direct EXCITATORY Pathway
Maintains Muscles activation during ongoing movements
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CORTEX activates STRIATUM with glutamate
STRIATUM inhibits GPI by GABA
SO the discharge of THALAMUS IS STIMULATED NOT INHIBTED stimulating CORTEX.
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Dopaminergic path of Subsstani Nigrar activates STRIATUM at D1 inhibiting the inhibitor GPI so stimulating THALAMUS Discharge Stimulating COOORTEX
Dopamine and Ach Effects on Direct pathway
DopaminE Excitatory Through SN ACTIVATING STRAITUM
ACH INHIBTORY
iNDIRECT Path of basal ganglia
describe !
For inhibtion of UNWANTED EXCESSIVE movements
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CORTEX stimulates the Striatum
inhibiting the GPE SO SUBTHALAMIC NUCELI IS STIMULATED STIMULATING GPI inhibting The THALAMUS Discharge to CORTEX
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tHE dOpaminergic path casues ?
Substania nigra give dopamin works on D2 on STRIATUM causing ? inhibtion of Striatum inhibotry effect on GPE CAUSING GPE to inhibit STN So GPI in inhibited and Thalamus is not inhibited so Increasing cortex Activity
Dopmaine and Ach effects of Indirect inhibotr path?
Dopamine inhibits the inhibotory path casuing exciation of cortex
Ach stimulates the inhibtory path
which part of SN release dopamine ?
Pars Compacta
Show Functions of Basal Ganglia !
MRA
=Modulation of Cortical Activity :
‘‘Prevents involntary muscle movements by inhibith talamo cortical activity
‘‘Aids in voulntary muscle movements :
-PlANNING : Caudate Circuit
aid in decision of The muscle to contract and its site , ordere , duration , speed and scale of contraction converting idea to PLAN!
-StORING and Excution of Learned Movements by Putamen Ciruit
Storing the learned skilled moevmetns to be done smoothly and lesion causing apraxia
-Gives postrual BACKground for skilled fine movemnents as it controls cortex venRtal corticospinal tract and the brainstem extrapyramidal tracts controllong the axial and proximal limb muscles
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=Regulation of Muscle tone
It is stimulating IRF inhbitig Y neurons
Inhibiting the Cortex Inhibiting alpha motor neurons
Caudate facilitatory but putamen and globus pallidus inhibitory
lesion causes? generalized hypertonia
the total effect casues inhibtion of muscle tone
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=Automatic Associated movements:-
As swinging of arms during wakling in Coordination with premotor area 6666666666666666666666666
Basal ganglai diseases Are cc by?
change in MUSCLE TONE
inVoluntary Mucle movments
in the contrALATERAL SIDE OF BODY
Chorea Hemiballismus Athetosis Parkinson
Chorea of Basal gangalia diseas describe ?
It is due to lesion to casudate nucleus
decreas gaba from the striatum to the GPe causing GPE to inhibit STN and GPI is inhibited so Increased ThalamoCortical Activity
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CC : Hypotonia as casudate is the only muscle tone facilitatory nucles in BG
Rapid sudden Involuntary dancing movmetns in disatl limb and facial muscles that relax with sleep and voluntary movments of affected limb
and INCREASED BY EMOTIONS
types of chorea
Huntington chorea casuing dementia
Sydenham Chora in RF In females
Hemiballismus ?
=Subthalamic nuclei lesion LOW glutamate
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Hypertonia
Sudden strong invoulntary movemnts in distal limb muscles
if ocuured bilateral ?
Laryngeal and Respiatrory spasm and death
