Final answer:
The substantia nigra is not part of the basal nuclei; it is located in the midbrain and is closely associated with the basal nuclei for movement control.
Step-by-step explanation:
To answer the question about which of the following is not part of the basal nuclei, let's define what is included in the basal nuclei. The basal nuclei, important for controlling movement, include the caudate nucleus, putamen, and globus pallidus. These structures, alongside the caudate, form the striatum, and the globus pallidus and putamen together are referred to as the lentiform nucleus. The substantia nigra, while being closely associated with the basal nuclei and critical for movement as it releases dopamine, is actually part of the midbrain and not one of the basal nuclei structures. Therefore, the substantia nigra is not part of the basal nuclei, making it the correct answer to the question.