Anatomy of Basal ganglia
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Transcript of Anatomy of Basal ganglia
Basal Ganglia
18-03-2015Dr Laxman Khanal
Assistant professor , department of anatomy
Nuclei
Introduction
• Comprise multiple sub-cortical nuclei withineach cerebral hemisphere.
• Comprises –corpus straitum, claustrum andamygdaloid nucleus.
• primary function is likely to control andregulate activities of the motor and pre-motorcortical areas so that voluntary movementscan be performed smoothly.
Does it have direct connection to motor nuclei ??Does it affect ipsi lateral or contra lateral side of body ?
Traditional classification
• Caudate nucleus
• Lentiform nucleus
• Amygdaloid body
• Claustrum
Clinical classification
• Caudate nucleus
• Lentiform nucleus
• Subthalamus
• Substantia nigra
Corpus straitum: caudate nucleus + lentiform nucleus
Lentiform nucleus: putamen (L) + globus pallidus
Striatum (or neostraitum): caudate + putamen
Palleostraitum: globus pallidus
Corpus straitum
• Lies lateral to thalamus
• Divided by band of nerve fibers (int capsule) into caudate and lentiform nucleus.
• Corpus straitum= caudate + lentiform nuclei
• Lentiform nucleus= globus pallidus + putamen
Caudate + putamen VS globus pallidus (=pale)or
Input Vs Output
c
Caudate nucleusHead – attached with putamen of lentiform nucleusBodyTail- attached with amygdaloid nucleus
What lies lateral to internal capsule ?What lies medial to internal capsule ?What lies lateral to lentiform nucleus ?
Lentiform Caudate + thalamusClaustrum
1. Third ventricle2. Thalamus and head of caudate3. Internal capsule4. Lentiform nucleus5. External capsule6. Claustrum7. Extreme capsule8. Insula9. Lat sulcus of brain
Motor cortexsensory cortex
striatum
Globus pallidus
Nucleus of thalamusSubstantia nigraBrain stem
Cranial nerve nuclei of brain stemAnterior horn cells of spinal cord
Motor function
Ansa lenticularis
Striatum
Globus pallidus
Direct pathwayIndirect pathway
Direct pathway turns up motor activityIndirect pathway turn down motor activity
?
Majority of neuron In corpus straitum areGABAergic and only few are cholinergic.
cerebrum
Thalamus
Straitum + GP
Glutamate Glutamate
GABA Direct pathway
Glutamate
Glutamate
GABA
Glutamate Indirect pathway
Glutamate
Glutamate
Glutamate
D1
D2
Role of substantia Nigra
ACH
Fine tuning of muscle activity is only possible bybalance between ACH and Dopamine
Lets summarize the pathways
• Direct pathway involves GP internus.
• Direct pathway is stimulatory to movement.
• Indirect pathway in involve GP externus and subthalamus in addition to structures of direct pathway.
• Indirect pathway is inhibitory to movement
• Dopamine stimulate direct pathway and inhibit indirect pathway; while ACH has opposite function.
Direct pathway Differences in- Indirect pathway
Form striatum to GP internus
Pathway From striatum to GP externus
Not involved Subthalamus Involved
Turn up motor activity
Function Turn down motor activity
Turns up via D1 Effect of Dopamine Turns down via D2
Turns down Effect of acetylcholine
Turns up
Parkinsonism
Hypokinesia
•Release of dopamine from Substantia nigra is less.•Less activation of direct pathway and less inhibition ofindirect pathway•May be associated with heroine addiction andantipsychotic drugs
Rigidity Restig tremor
Glutamate
Glutamate
Glutamate
D1
D2
Hyperkinesia disorders
• Hyperkinetic diseases are
– Chorea – caudate nucleus is involved
1. Huntington’s
2. Sydenham’s
3. Wilson’s disease
– Athetosis
– Ballismus (hemi) – subthalamus involved
Basal ganglia lesion are characterized bya. Ipsilateral movement disordersb. Spastic paralysisc. No atrophy of muscled. Hyper reflexia
Involuentary, quick ,jerky and nonrepetitive movement is called asa. Athetosis b. Choreac. Dystonia d. Tremor
What are the constituents of straituma. Caudate + globus pallidus b. caudate nucleusc. Caudate + lentiform d. caudate +putamen
Caudate nucleus is functionally similar witha. Globus pallidus b. Putamenc. Lentiform d. Claustrum
All the structures lie lateral to internal capsule except.a. Lentiform nucleus b. caudate nucleus c. External capsule d. Claustrum
Midbrain structure which give afferent to straitum is a. Crus cerebri b. Substantia nigrac. Tectum d. Tegmentum