has part has part characteristic of part of has modifier Abnormal basal ganglia morphology The basal ganglia are a group of nuclei (striatum, pallidum substantia nigra, and the subthalamic nucleus) at the base of the forebrain that are connected to the cerebral cortex, the thalamus, and other areas. The basal ganglia subserve motor functions that are distinct from those of the pyramidal (corticospinal) tract, for which reason neurologic abnormalities caused by lesions to the basal ganglia are often referred to as extrapyramidal. Abnormal cerebral subcortex morphology morphology abnormal basal ganglion