A subcortical loop exists within the brain linking upper motor neurons originating in the primary motor and pre-motor cortices and the brainstem, with the basal ganglia.
The basal ganglia include groups of motor nuclei located deep within the cerebral hemispheres, including the corpus striatum, which contains two nuclei named the caudate and putamen, and also the pallidum, which contains the globus pallidus and substantia nigra pars reticulate.