External globus pallidus

External Globus Pallidus

The External Globus Pallidus (GPe) is a subcortical structure of the brain that forms part of the basal ganglia system. It is involved in the regulation of voluntary movement. The GPe is a major component of the indirect pathway of movement, which functions to suppress unwanted movement.

File:Globus pallidus - very high mag.jpg

Micrograph of the globus pallidus with an H&E stain.

Anatomy

The globus pallidus is divided into two parts: the external globus pallidus (GPe) and the internal globus pallidus (GPi). The GPe is located laterally to the GPi. It is bordered medially by the internal capsule and laterally by the putamen, one of the structures that make up the striatum.

Function

The GPe plays a crucial role in the indirect pathway of movement. It receives inhibitory signals from the striatum and sends inhibitory signals to the subthalamic nucleus (STN). This results in the disinhibition of the STN, which can then send excitatory signals to the GPi and the substantia nigra, leading to the inhibition of movement.

Clinical Significance

Alterations in the function of the GPe can lead to movement disorders such as Parkinson's disease and Huntington's disease. In Parkinson's disease, there is an increased inhibitory output from the GPe, leading to a decrease in unwanted movement. In contrast, in Huntington's disease, there is a decreased inhibitory output from the GPe, leading to an increase in unwanted movement.

See Also

• Basal ganglia
• Internal globus pallidus
• Striatum
• Subthalamic nucleus