3. COMPONENTS
• Basal ganglia :- Group of nuclei (mass of grey
matter) in the forebrain and upper part of the
brain stem.(at the base of cerebral
hemispheres)
• Five grey nuclear masses:-
1) Caudate nucleus
2) Putamen
3) Globus pallidus
4) Substantia nigra
5) Sub thalamic nucleus
6) Red nucleus
4. CORPUS STRIATUM
• Subcortical masses of grey matter
situated in white core
• Divided into 2 parts by internal
capsule:-
1) Caudate nucleus
2) Lenticular nucleus :-
I. Putamen
II. Globus pallidus
5. CAUDATE NUCLEUS
• Highly curved , comma shaped band of grey
matter.
• Consists of head , body and tail.
• Separated from lenticular nucleus by
internal capsule .
6. LENTICULAR NUCLEUS
• Biconvex lens
• Triangular in both coronal and horizontal
sections.
• Divided into 2 parts by external lamina of
white matter.
9. SUBTHALAMIC NUCLEUS
• Biconvex mass of grey matter lateral to red nucleus
and lateral to substantia nigra.
• Separated from thalamus by Zona inserta.
10. SUBSTANTIA NIGRA
• Made up of small unpigmented and large pigmented
nerve cells.
• Contains neuromelanin
• Divided into 2 parts:-
1) Pars compacta- Contains dopaminergic (75%) and
cholinergic (25%) neurons.
2) Pars reticularis- Contains GABAergic neurons.
11. CONNECTIONS
• Main inputs – Corpus striatum ( Caudate nucleus & Putamen )
• Main output – Globus pallidus
12. PRIMARY FEEDBACK LOOP
Cerebral cortex Striatum
Globus pallidus &
substantia nigra
Thalamus
Supplementary
motor cortex
13. FUNCTIONS OF BASAL GANGLIA
• Control of voluntary motor activity.
• Control of reflex muscular activity.
• Control of muscle tone.
• Role in arousal mechanism.
14. Control of voluntary motor activity :-
• Cognitive control of motor activity.
• Neural discharge in Basal Ganglia begins well before the movement
begins.
• So basal ganglia is involved in planning and programming of movements.
• It is executed through functional neuronal circuits.
15. Timing and scaling of intensity of movements:-
• How rapidly and how much large the movements should be.
Subconscious execution of some movements:-
• Swinging of arms while walking
• Movements of facial expressions with emotions
• Movement of limbs while swimming
16. Control of reflex muscular activity
• Inhibitory effect on spinal reflexes.
• Regulate muscle which maintains
posture.
• Mainly visual and labyrinthine reflexes.
17. Control of muscle tone:-
• Substantia nigra of basal ganglia control Y motor neuron which
maintain muscle tone .
• Lesion- lead pipe type rigidity in parkinsonism
18. ROLE IN AROUSAL MECHANISM
• By connections of globus pallidus and red nucleus with reticular
formation .
• Lesion- Drowsiness, sleep.
20. PARKINSON’S DISEASE
( Paralysis agitans or shaking palsy)
• Described by James Parkinson in 1817.
• C/F :-
1) Akinesia or Hypokinesia ( unable to initiate voluntary movements or
decreased movements).
2) Mask like face.
3) Prolonged reaction time.
4) Shuffling or Festinant type gait.
5) Rigidity (lead pipe or cogwheel type rigidity)
21.
22. CHOREA
• Rapid ,jerky ,involuntary
movements.
• Due to damage to caudate nucleus.
• Seen in children as a complication to
rheumatic fever.
23. ATHETOSIS
• Slow, rhythmic, twisting, worm like movements of the extremities
• Mainly fingers and wrist.
• Due to damage to putamen
• Seen in children after birth injuries
24.
25. HUNTINGTON’S DISEASE
• Genetic disease
• Autosomal dominant disorder
• 30-50 years age
• Abnormal gene at short arm of chromosome 4.
• Lesion- Damage to GABAergic & cholinergic neurons of striatum to
pallidum.
• Hyperkinetic movements
• Slurred speech, dementia , jerky movement of hand.
26. HEMIBALLISM
• Cause:- Damage of subthalamic nucleus (commonly haemorrhage)
• c/f :- Violent involuntary limb movements , on one side of body
27. WILSON’S DISEASE
• Hepatolenticular degeneration by copper toxicity due to impaired biliary
excretion of copper.
• Changes more marked in lenticular nucleus mainly Putamen.
• C/f:- Parkinsonism,
Akinesia,
Muscle rigidity and
Tremors
