The basal ganglia are a cortico-subcortical neural network in the midbrain and the forebrain. The main components are the nuclei associated with the striatum, globus pallidus, substantia nigra and the subthalamic nucleus. The basal ganglia are connected with specific areas of the cortex and thalamus, forming complex circuits, the function and activity of which is not yet fully understood. At this point we can, to some extent, describe the function and dysfunction of five neural circuits: the motor circuit, the oculomotor circuit, the dorsolateral prefrontal circuit,the lateral orbitofrontal circuit, and the anterior cingulate circuit. Among these, the best described is the motor circuit, the pathology of which causes various hyperand hypokinetic disturbances and dystonias. The dysfunction of the basal ganglia that has received the most attention is Parkinson’s disease, which is best characterized by tremor at rest, akinesia and muscle rigidity. The purpose of the article is to provide a functional overview of the motor circuit of the basal ganglia in physiological and pathophysiological circumstances, based on the examples of Parkinson’s and Huntington’s disease.