Thalamus
- This is an approximately egg-shaped mass of neurons located in the diencephalon. The two thalami (right and left) form the lateral borders of the third ventricle.
- The thalamus is subdivided into nuclei (about 23 of them) each consisting of neuronal cell bodies and dendrites.
- The thalamus is the gateway to the cerebral cortex: all sensory and other incoming pathways to the cortex synapse here before their final set of neurons passes to their cortical destinations, with the exception of the olfactory pathway which enters by another route.
- The nuclei of the thalamus are grouped into anterior, medial and lateral regions, separated by a Y-shaped band of axons (laminae).
- The somatosensory pathways synapse in one of the ventro-posterior nuclei:
- spinal cord input - the ventro-posterior nucleus (VP), lateral part (VPL),
- trigeminal input from face, etc, - the medial part of VP (VPM).
