Neuroanatomy, Globus Pallidus

The globus pallidus (GP) is one of the components of the basal ganglia. It divides into globus pallidus internus (GPi) and globus pallidus externus (GPe). The globus pallidus and putamen collectively form the lentiform (lenticular) nucleus, which lies beneath the insula. The caudate nucleus and putamen form the corpus striatum. The corpus striatum is also an important part of the basal ganglia. The thalamus, subthalamus, and substantia nigra (SN) are not a part of the basal ganglia but serve essential functions for the network. The motor system controlled by basal ganglia is made of corticobulbar and subcortical structures, the gray matter of the spinal cord, cerebellum, and efferent nerves. The basal ganglia coordinate with other structures in the brain to plan and implement goal-oriented behaviors. This coordination requires multiple striatal (motor), cognitive, and limbic (reward) circuits and pathways. The globus pallidus can modulate these pathways because of its connections. The major output of the striatum is through the GPe. The GPi acts as the final output for both direct and indirect pathways of the basal ganglia network. The thalamus, however, is slightly different. It acts as a relay because of its reciprocal interconnections with cortical and subcortical structures. Therefore, the thalamus can perform multiple motor and sensory functions. These unique characteristics enable each component to work effectively. The dysfunction of the GP has been noted in ischemia, alcohol, and opiate abuse. This dysfunction gives rise to various cognitive and motor problems.