Basal ganglia: Encyclopedia II - Basal ganglia - Anatomical subdivisions

Basal ganglia - Anatomical subdivisions

The five individual nuclei that make up the primate basal ganglia are the striatum, external segment of the globus pallidus (GPe), internal segment of the globus pallidus (GPi), subthalamic nucleus (STN), and substantia nigra. Some of these nuclei may be further subdivided: for example, the striatum is separated into the putamen, caudate nucleus, and nucleus accumbens; the substantia nigra is generally divided into the pars compacta (SNc), pars reticulata (SNr), and pars lateralis (SNl).

These images show two schematic coronal cross-sections of the human brain with nuclei of the basal ganglia labeled on the right side. As it refers to a group of nuclei, the term "basal ganglia" is plural (the singular of ganglia is ganglion). However this is a misnomer as “ganglion” refers to a somatic cluster within the peripheral nervous system whereas the basal ganglia are located within the central nervous system (CNS). A somatic cluster within the CNS is referred to as a nucleus; it is for this reason some neuroanatomists refer to the basal ganglia as the “basal nuclei”.

There are two complete sets of basal ganglia in the mammalian brain mirrored in the left and right hemispheres. Two coronal sections are used to show the basal ganglia; the STN and substantia nigra lie deeper back in the brain (more caudal).

Adapted from the Wikipedia article "Anatomical subdivisions", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki