Substantia nigra

The substantia nigra is a darkly pigmented nucleus located in the midbrain. Its name means "black substance," derived from its high neuromelanin content. It is a critical component of the basal ganglia motor circuit. Its pars compacta region produces dopamine, which is essential for smooth, coordinated movement. The degeneration of these dopaminergic neurons is the primary cause of Parkinson's disease's motor symptoms.