Introduction
The thalamus, the lateral division of the diencephalon, plays a crucial role in sensory processing. This brain region receives precortical input from all sensory systems except for olfaction. It then projects this information primarily to the cerebral cortex, while also interacting with the basal nuclei and hypothalamus.
Boundaries of the Thalamus:
- Anteriorly: Interventricular foramen
- Posteriorly: Pulvinar
- Ventrally: Plane connecting hypothalamic sulci
- Dorsally: Surface underlying the fornix and lateral ventricle
- Medially: Third ventricle
- Laterally: Internal capsule
Functions of the Thalamus
The thalamus acts as a central hub, integrating sensory information from various sensory systems.
Thalamic Nuclei
The internal medullary lamina (IML) divides the thalamic nuclei into three main groups:
- Anterior Group: Located anterior to the IML.
- Medial Group: Situated adjacent to the third ventricle.
- Lateral Group: Positioned dorsolaterally to the IML.
Divisions of the Thalamic Nuclei:
- Ventral:
- Ventral anterior
- Ventral intermediate
- Ventral posterior
- Ventral posteromedial
- Ventral posterolateral
- Lateral:
- Lateral dorsal
- Lateral posterior
- Pulvinar
- Other:
- Reticular
- Intralaminar
- Midline
Mnemonic for remembering the divisions: RIM (Reticular, Intralaminar, Midline)
Blood Supply to the Thalamus
The posteromedial and posterolateral branches of the inferior cerebral artery provide blood supply to the thalamus.
Clinical Significance
Neoplasm invasion of the thalamus can lead to significant neurological deficits.
