Notes on Basal Nuclei

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BASAL NUCLEI (Ganglia)

Function:

The control of movements.

The term, corpus striatum is frequently used, and includes two structures (caudate nucleus and lentiform nucleus). The striatum refers to caudate nucleus and putamen.

Components:

Large nuclei at the base of the cerebral hemispheres.

1. Caudate nucleus - C-shaped and consists of a head, body and tail. Tail communicates with the amygdaloid nucleus (influences movement, endocrine and feeding functions).

2. Lentiform nucleus: consists of the putamen and globus pallidus (latter is further divided into an internal and external division) (paleostriatum). Separated from the thalamus by the internal capsule.

3. Amygdaloid nucleus: Associated with limbic and olfactory systems (see 1).

4. Claustrum: thin sheet of grey matter between lentiform nucleus and insula. Function unclear. Extreme capsule lies lateral and external capsule medially.

5. Corpus striatum refers to caudate and lentiform nuclei.

6. Neostriatum refers to the caudate nucleus and putamen.

7. Subthalamic nucleus.

8. Substantia nigra (pars compacta).

Projections:

Afferent and efferent pathways (to thalamus and cortex). A failure of the nigrostriatal pathway is associated with Parkinson's Disease and the release of dopamine.

Functions:

1. Part of the "extrapyrmidal system." Modulation of motor outflow.

2. Connections:

a. Cerebral cortex: motor and premotor areas (motor control) - control of movement. Smoothing of voluntary actions.

b. Thalamic and subthalamic nuclei.

c. Cerebellum.

d. Substantia nigra.

e. With limbic system.

Dysfunction: Results in dyskinesias ie rigidity, rapid and aimless movements, tremor, chorea, ballism and athetosis; Parkinson's disease.

3. Putamen processes sensorimotor data and the caudate nucleus integrates fibres destined for the prefrontal cortex association areas.

4. Putamen and globus pallidus: Motor activity integration.

5. Globus pallidus: major efferent nucleus with projections to the thalamus, hypothalamus and midbrain. Regulates muscle tone for specific, intentional body movements.

6. Acts in concert with the cerebral cortex and corticospinal system.

7. Putamen circuit: Connections include sensory and motor cerebral cortex, globus pallidus, thalamus, subthalamus and substantia nigra. Important for performing learned patterns of movement ie writing, cutting paper, hammering nails, throwing a ball.

8. Caudate circuit: Important for cognitive control of motor activity. Neural connections include globus pallidus, thalamus and cerebral cortex.

9. Important for the timing and scaling functions.

10. Associated with important specific neurotransmitter pathways.

a. Dopamine pathway (subst. nigra to caud. nucleus and putamen).

b. Gamma-aminobutyric acid (GABA) pathway (Caud. nucleus to subst. nigra.)

c. Acetylcholine pathway (Cortex to the caudate nucleus and putamen).

d. Norepinephrine, serotonin and enkephalin pathways. Multiple pathways connect the ganglia with the cerebrum.

Further Topics on Subcortical Grey Matter:

1. Notes on Thalamus
2. Notes on Pineal Gland
3. Notes on Hypothalamus
4. Notes on Limbic System
5. Notes on Pituitary Gland
6. Notes on Basal Nuclei
7. Amygdaloid Body and Temporal Lobe

Additional Reading:

Basic Neurology

1. Peripheral Nervous System
2. Central Nervous System
3. The Ventricular System
4. The Spinal Cord
5. The Brain Stem
6. The Cerebellum
7. Visual Pathways
8. Diencephalon
9. Basal Ganglia
10. Cerebral Cortex
11. Sleep Disorders
12. Autonomic Nervous System
13. Cranial Nerves and Parasympathetic Ganglia
14. Cells of the Nervous System
15. Cerebrospinal fluid
16. Additional short notes on Cerebrum
17. Functions and Diseases of Cerebrum
18. Subcortical Grey Matter
19. Notes on The Spinal Cord
20. Regulation of Heart Rate by Autonomic Nervous System
21. Action Potentials, Axon Conduction, and Neuromuscular Junction
22. Types of Seizures
23. What is a Cough Reflex?
24. Notes on Congenital Prosopagnosia
25. Findings in Parkinson's Disease
26. Types of Heat Strokes
27. Types of Strokes
28. What is Benign Intracranial Hypertension?
29. What is Cauda Equina Syndrome?
30. Cranial Nerve Locations in Brain Stem
31. What is a Cluster Headache?
32. What is a Subarachnoid Hemorrhage?
33. What is a Tension Headache?

Neurology Videos

1. Video of Neurology Examination in a Clinical Setting

Medical Images

Useful Medical Images & Diagrams (link opens in a new window)

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1. Nervous System Disorders
2. Histology of Nervous Tissue
3. Cranial Nerve Reflexes
4. Motor System Examination

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