Basal Ganglia

Sections

Summary
Full Text

Summary

Basal ganglia (basal nuclei)

• Basal ganglia (basal nuclei)
  • Motor function, most notably.

Structures

• Caudate (head) is anterior-most portion of the basal ganglia.
• Lentiform nucleus: lens-shaped, posterolateral
  • Putamen (laterally)
  • Globus pallidus (medially)
• Internal capsule
  • Space between the lentiform nucleus, caudate head, and thalamus
  • Comprises tightly packed fiber bundles that originate from widespread brain regions

Clinical Correlations

• Basal Ganglia Stroke
• Intracranial Hemorrhage: Basal Ganglia
• Stroke: Internal Capsule

Full Text

brain: inferior view

Cerebral Lobes

• Begin with an inferior view of the brain. Draw only one half now.
• In this view, we can see, most notably, the frontal (orbital) surface and the temporal lobe.
• Shade the lobes of the brain as follows:
  • Anterior is the frontal lobe.
  • Lateral middle is the temporal lobe.
  • Medial middle is the limbic lobe.
  • Posterior is the occipital lobe.

Basal Ganglia

Now, on the other half of the brain, let's focus on the basal ganglia.

• First, as a reference point, draw a cerebral ventricle: the frontal horn of the lateral ventricle.

• Denote that the basal ganglia (aka basal nuclei) are most notably involved in motor function but have numerous other functions, as well.

• Along the lateral wall of the frontal horn of the lateral ventricle, draw the head of the caudate, which is the anterior-most portion of the basal ganglia.
  • Denote that it is a major relay center, which is essential to motor output in a similar way, as we'll see, that the thalamus is a major relay center, essential to sensory integration.
• Posterolateral to it, draw the lens-shaped lentiform nucleus.
• Subdivide it into the putamen, laterally, and the globus pallidus, medially. Imagine a putaminal shell around a globus pallidus core.
• Next, medial to the lentiform nucleus, draw the thalamus (of the diencephalon), which is the primary sensory relay center.
• Next, label the space between the lentiform nucleus, caudate head, and thalamus as the internal capsule, which comprises tightly packed fiber bundles that originate from widespread brain regions.
  • Denote that the motor function of the internal capsule is the most clinically-relevant: a stroke within the internal capsule causes a "pure motor stroke."
  • As an oversimplification, think of the thalamus for sensory input and the internal capsule for motor output.