The substantia nigra is a small, darkly pigmented region located in the midbrain, part of the brain's basal ganglia system. It plays a crucial role in movement control and is involved in the regulation of reward and addiction. The substantia nigra contains neurons that produce the neurotransmitter dopamine, which is essential for smooth and coordinated muscle movements. Damage to the substantia nigra is associated with several neurological disorders, most notably Parkinson's disease. In this condition, the loss of dopamine-producing neurons leads to symptoms such as tremors, stiffness, and difficulty with balance and coordination. Understanding the function of the substantia nigra is vital for developing treatments for these movement disorders.