The basal ganglia comprise multiple subcortical nuclei that primarily function to regulate motor control. They include the corpus striatum, made up of the caudate nucleus and lentiform nucleus (containing the putamen and globus pallidus). The basal ganglia nuclei are connected in direct and indirect pathways that facilitate movement. The direct pathway stimulates movement via the globus pallidus internus, while the indirect pathway inhibits movement via the globus pallidus externus and subthalamus. Dopamine stimulates the direct pathway while acetylcholine stimulates the indirect pathway. Basal ganglia disorders result from imbalances in these pathways, such as Parkinson's disease from reduced dopamine signaling.

1. Basal Ganglia
18-03-2015
Dr Laxman Khanal
Assistant professor , department of
anatomy
Nuclei

2. Introduction
• Comprise multiple sub-cortical nuclei within
each cerebral hemisphere.
• Comprises –corpus straitum, claustrum and
amygdaloid nucleus.
• primary function is likely to control and
regulate activities of the motor and pre-motor
cortical areas so that voluntary movements
can be performed smoothly.

3. Does it have direct connection to motor nuclei ??
Does it affect ipsi lateral or contra lateral side of body ?

5. 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

6. 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

8. c
Caudate nucleus
Head – attached with putamen of lentiform nucleus
Body
Tail- attached with amygdaloid nucleus

9. What lies lateral to internal capsule ?
What lies medial to internal capsule ?
What lies lateral to lentiform nucleus ?
Lentiform
Caudate + thalamus
Claustrum

13. 1. Third ventricle
2. Thalamus and head of caudate
3. Internal capsule
4. Lentiform nucleus
5. External capsule
6. Claustrum
7. Extreme capsule
8. Insula
9. Lat sulcus of brain

15. Motor cortex
sensory cortex
striatum
Globus pallidus
Nucleus of thalamus
Substantia nigra
Brain stem
Cranial nerve nuclei of brain stem
Anterior horn cells of spinal cord
Motor function
Ansa lenticularis

17. Striatum
Globus pallidus
Direct pathway
Indirect pathway
Direct pathway turns up motor activity
Indirect pathway turn down motor activity
?
Majority of neuron In corpus straitum are
GABAergic and only few are cholinergic.

18. cerebrum
Thalamus
Straitum + GP

19. Glutamate
Glutamate
GABA Direct pathway

20. Glutamate
Glutamate
GABA
Glutamate
Indirect pathway

21. Glutamate
Glutamate
Glutamate
D1
D2
Role of substantia Nigra
ACH

22. Fine tuning of muscle activity is only possible by
balance between ACH and Dopamine

23. 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.

24. 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

25. Parkinsonism
Hypokinesia
•Release of dopamine from Substantia nigra is less.
•Less activation of direct pathway and less inhibition of
indirect pathway
•May be associated with heroine addiction and
antipsychotic drugs
Rigidity Restig tremor

27. Glutamate
Glutamate
Glutamate
D1
D2

28. 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

30. Basal ganglia lesion are characterized by
a. Ipsilateral movement disorders
b. Spastic paralysis
c. No atrophy of muscle
d. Hyper reflexia
Involuentary, quick ,jerky and nonrepetitive movement is called
as
a. Athetosis b. Chorea
c. Dystonia d. Tremor
What are the constituents of straitum
a. Caudate + globus pallidus b. caudate nucleus
c. Caudate + lentiform d. caudate +putamen

31. Caudate nucleus is functionally similar with
a. Globus pallidus b. Putamen
c. 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 nigra
c. Tectum d. Tegmentum