Dorsal thalamus

  • The largest nucleus of the brain
  • Broadly ovoid-shaped with a large forward and medially oblique axis
  • Length 40mm, width 18-20 mm, height 20-22 mm

Topography

  • Under the lateral ventricle and choroid taenia (which harbour the choroid plexus)
  • Above the hypothalamic area, the subthalamus and midbrain
  • Behind the fornix and interventricular foramen
  • In front of the habenula and pineal body
  • Laterally to the 3rd ventricle, stria medullaris and habenular commissure
  • Medially to the internal capsule

Thalamic nuclei

The thalamus consists of nuclear groups which may themselves be subdivided into various individual nuclei. Advanced macro- and microscopic techniques enabled the identification of further thalamic subdivisions, which explains the coexistence of several classifications listing diverse thalamic nuclei.

Here we describe some of the most commonly acknowledged nuclear groups and nuclei. Their location on the sections and diagrams are extrapolated from the referenced sources.

Two laminas of white matter run through the thalamus:

Nuclear groups of the thalamus

  • Anterior nuclei
  • Lateral nuclei
    described as the lateral dorsal nucleus and lateral posterior nucleus
  • Intralaminar nuclei
    tha main one is called the centromedian nucleus
  • Medial nuclei
    the main one is the mediodorsal nucleus
  • Median nuclei
  • Ventral nuclei
    described by the ventral anterior nucleus, the ventral lateral complex and ventrobasal complex
  • Reticular nucleus
  • Pulvinar
  • Medial and lateral geniculate bodies
    described together as metathalamus,sometimes regarded as separate from the thalamus