Basic anatomy OF THE THALAMUS

The thalamus is believed to both process and relay sensory information selectively to various parts of the cerebral cortex. The two thalami are prominent bulb-shaped masses about 5.7 cm in length, located on each side of the 3rd ventricle, and form the major part of the diencephalon. The thalamus is composed of a complex system of myelinated neurons separated by distinct clusters of neuron cell bodies, which form specific nuclei. Figure 9.1 shows the anatomical arrangement of the thalamus, with clusters of nuclei being divided into three main parts: anterior, medial and lateral, by the intralaminar nucleus. The lateral part is further sub-divided into dorsal and ventral tiers.

Function of the thalamus

Traditionally, the thalamus was considered to act as a relay station within the central nervous system subserving both sensory and motor mechanisms. However, the extent of its afferent and efferent connections with the periphery and the brain and the mass of interconnections between the thalamic nuclei implies that in addition, it has a significant role in controlling and modifying this information. More precisely, the corticothalamic system appears to synchronize the activity of thalamic and cortical neurons.

As a result of its widespread connections, damage to the thalamus may cause a range of presentations.