substantia nigra (nucleus niger, Soemmerring's ganglion)

Structure

• the substantia nigra is a nucleus of the midbrain, crescentic on transverse section extending from the rostral border of the pons into the subthalamic region
• it contains a dorsal stratum of closely spaced pigmented, melanin-containing cells, the pars compacta, & a larger ventral region of widely scattered cells, the pars reticulata

Afferents

• the pars compacta contains dopaminergic neurons which project to the striatum (caudate & putamen)
• other non dopaminergic neurons project to the rostral part of the ventral nucleus of the thalamus
• the pars reticulata forms part of the output system for the striatum

Efferents

• the nigrostriatal system is reciprocated by a massive striatonigral fiber system with multiple neurotransmitters, but chiefly GABA
• smaller afferent projections are received from
  • subthalamic nucleus
  • the lateral segment of the globus pallidus
  • the dorsal nucleus of the raphe
  • the pedunculopontine nucleus of the midbrain

More general terms

• CNS nucleus

Additional terms

• nigrostiatal system/tract

Component of

• mesencephalon (midbrain)

Components

• pars compacta
• pars reticulata