Internal globus pallidus
| Medial globus pallidus | |
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Medial globus pallidus (GPI) is seen in the 2nd image from the left
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| Details | |
| Identifiers | |
| Latin | Globus pallidus medialis, globus pallidus internus |
| NeuroNames | hier-215 |
| NeuroLex ID | Globus pallidus internal segment |
| TA | A14.1.09.511 |
| FMA | 61840 |
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Anatomical terms of neuroanatomy
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The medial globus pallidus (or internal, GPi) is one of the output nuclei of the basal ganglia (the other being the substantia nigra pars reticulata). The GABA-containing neurons send their axons to specific nuclei of the dorsal thalamus (VA and VL), to the centromedian complex and to the pedunculopontine complex.
The efferent bundle is constituted first of the ansa and fasciculus lenticularis, then crosses the internal capsule as the Edinger's comb system then arrives at the laterosuperior corner of the subthalamic nucleus and constitutes the field H2 of Forel, then H, and suddenly changes its direction to form field H1 that goes to the inferior part of the thalamus. The distribution of axonal islands is widespread in the lateral region of the thalamus. The innervation of the central region is done by collaterals.
The medial globus pallidus contains GABAergic neurons, which allow for its inhibitory function. As the medial globus pallidus, along with the substantia nigra pars reticulata, forms the output of the basal ganglia, these neurons extend to the thalamus, the centromedian complex and the pedunculopontine complex.
The medial globus pallidus acts to tonically inhibit the ventral lateral nucleus and ventral anterior nucleus of the thalamus. As these two nuclei are needed for movement planning, this inhibition restricts movement initiation and prevents unwanted movements.
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