The subthalamic nuclei are small paired structures that are part of the functional basal ganglia. They are located ventral to the thalamus, dorsal to the substantia nigra and medial to the internal capsule.
The subthalamic nucleus receives its main input from the lateral pallidum (external segment of the globus pallidus). Excitatory, glutamatergic inputs come from the cerebral cortex (particularly the motor cortex), and from the pars parafascicularis of the central complex. There are also neuromodulatory inputs from the substantia nigra pars compacta.
The axons of its neurons leave the nucleus dorsally. The efferent axons are glutamatergic and most of the subthalamic principal neurons are directed to the other elements of the core of the basal ganglia.
They were first described by the French neurologist Jules Bernard Luys (1828-1897) in 1865 and the term corpus Luysii or Luys' body is still sometimes used.