Anatomy of Basal ganglia

good description of basal ganglia and pathways

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 ?

4. 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

5. 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

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

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

8. Third ventricle Thalamus and head of caudate Internal capsule Lentiform nucleus External capsule Claustrum Extreme capsule Insula Lat sulcus of brain

9. 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

10. 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.

11. cerebrum Thalamus Straitum + GP

12. Glutamate Glutamate GABA Direct pathway

13. Glutamate Glutamate GABA Glutamate Indirect pathway

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

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

16. 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.

17. 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

18. 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

19. Glutamate Glutamate Glutamate D1 D2

20. Hyperkinesia disorders Hyperkinetic diseases are Chorea – caudate nucleus is involved Huntington’s Sydenham’s Wilson’s disease Athetosis Ballismus (hemi) – subthalamus involved

21. Thank you for your patience

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

23. 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