Basal ganglia and amygdala


1. Globus pallidus internus

Globus pallidus internus is one of the two parts of the globus pallidus, the other part is globus pallidus externus. Both globus pallidus internus and globus pallidus externus are components of the basal ganglia and receive similar input, but they have very different output. Whereas both globus pallidus internus and globus pallidus externus receive input from the striatum, only globus pallidus internus is a major source of output from the basal ganglia.

  • 1.
    Globus pallidus internus
  • 2.
    Globus pallidus externus
  • 3.
  • 4.
    Caudate nucleus
  • 5.
    Internal capsule
  • 6.
  • 7.
  • 8.
    Ansa lenticularis
  • 9.
    Corpus callosum
  • 10.
    Corona radiata
  • 11.
    Cingulate gyrus
  • 12.
  • 13.
  • 14.
    Fornix (plural fornices)
  • 15.

In this view we see:

  • The coronal section of the brain showing the deep basal ganglia and amygdala, which are not visible in the mid-sagittal view in Image 2.
  • The corpus callosum crossing between the two hemispheres. The corpus callosum and other structures seen in Image 2 appear very different here.
  • Three components of the basal ganglia: caudate nucleus, putamen and globus pallidus. The basal ganglia are a group of nuclei situated deep within each cerebral hemisphere and consist of the caudate nucleus, putamen, globus pallidus, subthalamic nucleus (seen in Image 6) and substantia nigra (seen in Image 10). Note that:
    • the caudate nucleus and putamen are separated from each other by the internal capsule, which also separates the globus pallidus from the thalamus;
    • the left and right amygdalae are visible inferior to the globus pallidus and internal capsules on each side of the brain;
    • the amygdala, like the thalamus, is not part of the basal ganglia.


Like all three forebrain components of the basal ganglia, each caudate nucleus is located deep within the cerebral hemispheres and has connections to the prefrontal cortex of the frontal lobe.

The caudate nucleus arches over the top of the putamen and thalamus, and curves down and behind both structures. It is closely associated with each lateral ventricle.


The caudate nucleus, like the ventricles (as seen in Image 2) and several other structures in the brain, is C-shaped. It looks like a tadpole and has a head, a body and a tail. The head of the caudate nucleus bulges into the anterior horn of the lateral ventricle (as seen here). The caudate body is lateral to the body of the lateral ventricle, and its tail borders the inferior horn of the lateral ventricle.

The caudate nucleus contains both projection neurons and interneurons and can be subdivided into compartments.

The caudate nucleus and putamen have similar origins and connections and together are called the striatum.


Being connected to the prefrontal cortex of the frontal lobe, where the highest forms of cognition including thinking, assessing and planning occur, determines its function. The caudate nucleus is involved in organising and planning movement rather than actual execution of movement.