1 basal ganglia

15,750 views

Published on

  • Be the first to comment

1 basal ganglia

  1. 1. BASAL GANGLIA 1
  2. 2. Motor Cortex + Via Via Thalamus ThalamusBasal Ganglia Cerebellum UMN Motor neurons & Interneurons in Spinal Cord LMN Skeletal Muscle Modulation of motor activity by Basal Ganglia & Cerebellum 2
  3. 3. Def:• Large masses of grey matter• situated within the white core of each cerebral hemisphere• Essential constituents of the extra pyramidal system 3
  4. 4. FUNCTIONSModulation 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 4
  5. 5. – 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. 5
  6. 6. Basal Ganglia - ComponentsAnatomicalCorpus striatumClaustrumAmygdaloid body 6
  7. 7. 7
  8. 8. 8
  9. 9. Physiological/clinical• Corpus striatum• Subthalamic nu• Substantia nigra 9
  10. 10. 10
  11. 11. • Phylogenetically: – Neostriatum: • Caudate nuc + Putamen – Palaeostriatum: • Globus Pallidus 11
  12. 12. 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 12
  13. 13. CAUDATE NUCLEUS• Comma shaped band of grey matter• 3 Parts : Head, Body & Tail 13
  14. 14. CAUDATE NUCLEUS :• Lies in conformity with curvature of Lat ventricle 14
  15. 15. HEAD of C NucleusBulges into the floor of Ant horn of Lat VLaterally : Ant limb of Int capsule & Lentiform Nu (Ant limb) 15
  16. 16. Relations of BODY:Inferomedially :• Floor of central part of Lat Ventricle• Accompanied med by Stria terminalis & thalamostriate veinSuperolaterally : Corpus callosum, Fronto-occipital fasciculus Lat ventricle (Central part) Fronto-occipital Fasciculus Body of caudate Nu Thalamo-striate vein Stria terminalis 16
  17. 17. TAILPasses Dwn & Fwd along roof of Inf horn of Lat V Tail of C N 17
  18. 18. TAIL of C N : Caudate Nucleus• Medially : Lentiform Nu - Str Terminalis - Sublentiform part of IC &Thalamus• anterior: Amygdaloid body Str Terminalis• Above : Lentiform Nu Tail of C Nu Inf horn of lat ventricle Substantia Nigra 18
  19. 19. LENTIFORM NUCLEUS Caudate Nucleus•Large & wedge shaped Lentiform Nu•Narrow part of wedge facingmedially Ext CapsuleRELATIONS Claustrum Str Terminalis• Laterally : Tail of C Nu • Ext capsule & Inf horn of lat ventricle Claustrum Substantia Nigra 19
  20. 20. Caudate Nucleus Lentiform Nu• Medially : Int Capsule Thalamus Ext Capsule Head of Caudate Nu Claustrum Str Terminalis Tail of C Nu• Above : Corona radiata Inf horn of lat ventricle Substantia Nigra 20
  21. 21. Caudate Nucleus• Below Lentiform Nu •Ant Perf substance •Inf horn of Lat V •Sublentiform part of IC, Ext Capsule Claustrum •Tail of C Nu & Str Terminalis •Stria terminalis Tail of C Nu Inf horn of lat ventricle 21
  22. 22. 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 22
  23. 23. CONNECTIONS• Afferent- Caudate Nucleus & Putamen• Efferent- Globus Pallidus AFFERENTS EFFERENTS 23
  24. 24. CONNECTIONS : STRIATUMAFFERENTS-• Cortico-striate : from entire Neocortex• Thalamo - striate : Centro-median nu of Thalamus• Nigro- striate : From Pars compacta of S NigraEfferents Strio-pallidal Strio nigral (To Pars reticularis of S Nigra) 24
  25. 25. 25
  26. 26. • Connections- Striatum 26
  27. 27. GLOBUS PALLIDUS :AFFERENTS :• Strio-pallidal : from CN & Putamen• From Subthalamus 27
  28. 28. 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 28
  29. 29. • Connections - Paleostriatum 29
  30. 30. p.c.- pars compacta p.r.- pars reticularisSchematic Diagram showing connections of Basal Ganglia 30
  31. 31. 31
  32. 32. LEISIONS OF B GManifestations- Two types.• Hypokinetic, hypertonic : – Increased tone & rigidity – Eg : Parkinsonism• Hyperkinetic hypotonic : – Abnormal involuntary movements - dyskinesias Eg : Athetosis, Chorea & Ballism 32
  33. 33. • Organic basis of Parkinson’s disease: – Degeneration of dopaminergic neurons from the substantia nigra (Nigrostriate fibres) 33
  34. 34. • 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 34
  35. 35. 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 35
  36. 36. • Mask face : No emotional response• Difficulty in taking initial steps & stopping movements• Resting tremor – Pill rolling move of hands 36
  37. 37. • 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. 37
  38. 38. ATHETOSIS• Slow worm like writhing movements affecting fingers & wrist• Due to damage of Putamen – in birth injury 38
  39. 39. 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. 39
  40. 40. 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 40
  41. 41. Sydenham’s Chorea :• In childhood –• A complication of Rheumatic (Streptococcal) fever• Scattered minute hemorrhage & capillary emboli in striatum• Recover completely 41
  42. 42. 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 42
  43. 43. 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 43
  44. 44. 44

×