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1
BASAL GANGLIAA journey into the deep nuclei
Dr Anil Dwivedi
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Motor Cortex
Basal Ganglia Cerebellum
+Via
ThalamusVia
Thalamus
Motor neurons & Interneurons in Spinal Cord
Modulation of motor activity by Basal Ganglia & Cerebellum
UMN
Skeletal Muscle
LMN
3
Def:• Large masses of grey
matter • situated within the white
core of each cerebral hemisphere
• Essential constituents of the extra pyramidal system
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FUNCTIONS Modulation of motor activities through neuronal
circuits:
– Production of movements• Maintain purposeful motor activity while
suppressing unwanted or useless movement
– Regulate muscle tone• Inhibit muscle tone throughout the body
– proper muscle tone is maintained through a balance of excitatory and inhibitory inputs
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– Monitor and coordinate slow, sustained contractions related to posture and support.
– Avoid abnormal involuntary movements– Control group of movements for
emotional expretion– Memory, emotion, and other cognitive
functions.
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Basal Ganglia - Components
AnatomicalCorpus striatumClaustrumAmygdaloid body
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Physiological/clinical• Corpus striatum• Subthalamic nu• Substantia nigra
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• Phylogenetically:– Neostriatum:
• Caudate nuc + Putamen– Palaeostriatum:
• Globus Pallidus
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BASAL GANGLIA
• New classification
• Dorsal
• Dorsal striatum : Caudate Nu + Putamen
• Dorsal Pallidum : G Pallidus (Inner & outer segts)
• Ventral :
• Ventral striatum : Nu Acumbens & Olf tubercle• Ventral pallidum : Loc below Ant commissure in Ant perf
substance
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CAUDATE NUCLEUS • Comma shaped band of grey matter • 3 Parts : Head, Body & Tail
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CAUDATE NUCLEUS :• Lies in conformity with curvature of Lat ventricle
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HEAD of C Nucleus
Bulges into the floor of Ant horn of Lat V
Laterally : Ant limb of Int capsule & Lentiform Nu
(Ant limb)
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Relations of BODY:
Inferomedially :
• Floor of central part of Lat Ventricle
• Accompanied med by Stria terminalis & thalamostriate vein
Superolaterally : Corpus callosum, Fronto-occipital fasciculus
Body of caudate NuThalamo-striate vein
Stria terminalis
Lat ventricle (Central part)
Fronto-occipital Fasciculus
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TAIL
Tail of C N
Passes Dwn & Fwd along roof of Inf horn of Lat V
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Substantia Nigra
Caudate Nucleus
Lentiform Nu
Tail of C Nu
Inf horn of lat ventricle
Str Terminalis
TAIL of C N :
• Medially :
- Str Terminalis - Sublentiform part of IC & Thalamus
• anterior: Amygdaloid body
• Above : Lentiform Nu
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Substantia Nigra
Caudate Nucleus
Lentiform Nu
Tail of C Nu
Inf horn of lat ventricle
Str Terminalis
•Large & wedge shaped
•Narrow part of wedge facing
medially
RELATIONS
• Laterally :
• Ext capsule & Claustrum
LENTIFORM NUCLEUS
Ext CapsuleClaustrum
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Substantia Nigra
Caudate Nucleus
Lentiform Nu
Tail of C Nu
Inf horn of lat ventricle
Str Terminalis
• Medially :
Int Capsule
Thalamus
Head of Caudate Nu
• Above : Corona radiata
Ext CapsuleClaustrum
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Caudate Nucleus
Lentiform Nu
Tail of C Nu
Inf horn of lat ventricle
Str Terminalis
• Below
• Ant Perf substance
• Inf horn of Lat V
• Sublentiform part of IC,
• Tail of C Nu &
• Stria terminalis
Ext CapsuleClaustrum
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Blood Supply• Arterial
– Medial Striate Brs. - MCA
– Lat. Striate Brs. – MCA– Recurrent Br – ACA– Ant. Choroidal Br -
MCA
• Venous– Striate veins– Int. cerebral vein– Basal Vein
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CONNECTIONS
• Afferent- Caudate Nucleus & Putamen • Efferent- Globus Pallidus
AFFERENTS
EFFERENTS
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CONNECTIONS : STRIATUM
AFFERENTS-
• Cortico-striate : from entire Neocortex
• Thalamo - striate : Centro-median nu of Thalamus• Nigro- striate : From Pars compacta of S Nigra
Efferents
Strio-pallidal
Strio nigral (To Pars reticularis of S Nigra)
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• Connections-Striatum
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GLOBUS PALLIDUS :
AFFERENTS :
• Strio-pallidal : from CN & Putamen
• From Subthalamus
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GLOBUS PALLIDUS :
EFFERENTS : Pallido-fugal • To Thalamus :
– Thru Ansa lenticularis & Fasciculus Lenticularis – Join to form Fasciculus thalamicus– End in VA, VL & CM nuclei
• To Subthalamus : From Outer Segt of GP
• To Reticular formation of MB
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• Connections - Paleostriatum
30Schematic Diagram showing connections of Basal Ganglia
p.c.- pars compacta p.r.- pars reticularis
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LEISIONS OF B G
Manifestations-
Two types.• Hypokinetic, hypertonic :
– Increased tone & rigidity – Eg : Parkinsonism
• Hyperkinetic hypotonic : – Abnormal involuntary movements - dyskinesias
Eg : Athetosis, Chorea & Ballism
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• Organic basis of Parkinson’s disease: – Degeneration of dopaminergic neurons from the
substantia nigra (Nigrostriate fibres)
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• The net effect is reduced excitation of motor cortex. – loss of dopamine
producing neurons
– globus pallidus becomes overactive
– inhibition of the VL nucleus of the thalamus
– reduced excitation of the cortex
hypokinesia
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PARKINSON’S DISEASE (Paralysis Agitans)
• Characterized by Rigidity
& tremors
• Rigidity – Caused by
increased muscle tone
– Due to increased
activity of static gama
fusiform fibers
• Affects all muscles, Cog-
wheel rigidity, Short quick
steps
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• Mask face : No emotional response
• Difficulty in taking initial steps & stopping movements
• Resting tremor – Pill rolling move of hands
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• Cause : • Degenerative changes in
Globus Pallidus & S Nigra• Marked reduction in Dopamine
• Treatment : • Admn of L- Dopa• Surgical destruction of GP /
VL Nu of Thalamus • Striatal implants of dopamine
containing neurons of fetal origin.
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ATHETOSIS
• Slow worm like writhing movements affecting fingers & wrist
• Due to damage of
Putamen – in birth injury
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HEMIBALLISM
• Wild flail like movements of one arm
• Degeneration of Subthalamic nucleus of Opp side• Damage to subthalamus decreases excitation of the
globus pallidus internal segment resulting in less inhibition of thalamus causing hyperkinetic disorder.
• Common cause is lacunar infarct of subthalamic nucleus.
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CHOREA • ”Dance like” movements• Brisk, jerky, purposeless
movements in distal parts of extremities asso with twitching of face
• Two types : – Sydenham’s Chorea– Huntington’s chorea
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Sydenham’s Chorea :
• In childhood –
• A complication of Rheumatic (Streptococcal) fever • Scattered minute hemorrhage & capillary emboli in
striatum
• Recover completely
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Huntington’s chorea :
• In middle age –
• Autosomal Dominant type
• Degeneration of Striatum & Cerebral cx
• Striatal neurons in caudate/Putamen degenerate leading
to decreased activity in the GP internal segment resulting
in less inhibition of thalamus causing a hyperkinetic
disorder.
• Mental deterioration
• Decreased level of GABA in Strio-nigral neurons
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WILSON’S DISEASE (Hepato-lenticular degeneration) :
• Genetic error of Copper metabolism
• Muscular rigidity, Tremor
• Impairment of movements
• Uncontrolled Laughing / Crying
• Degn & cavitation of Putamen, Cirrhosis of Liver
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Thank You