Dorsal Thalamus

Dorsal Thalamus

The dorsal thalami are two large, ovoid nu-clear complexes. Their medial surfaces form the wall of the third ventricle, while their lateral surfaces border on the internal capsule. They extend from the interventricular foramen (foramen of Monro) to the quad-rigeminal plate of the midbrain.

The two thalami are the relay stations formost sensory pathways, almost all of whichterminate in the contralateral thalamus. Fiber bundles connect the thalami also with the cerebellum, globus pallidus, striatum, and hypothalamus.

Thalamic Radiation (A)

The thalamus (A1) is connected to the cere-bral cortex by the corona radiata, or thalamic radiation (A2 – 4). The fibers runobliquely through the internal capsule toward the cerebral cortex. The more prom-inent bundles are the anterior thalamic radia-tion (A2) (to the frontal lobe), the superior thalamic radiation (A3) (to the parietal lobe),the posterior thalamic radiation (A4) (to the occipital lobe), and the inferior thalamicradiation (to the temporal lobe).

The great variety of fiber connections indi-cates the central function of the thalamus, which is directly or indirectly integrated into most systems. Accordingly, it is not a uniform structure but a highly organized complex consisting of diversely structured nuclear groups.

Based on their fiber connections, two types of thalamic nuclei are distinguished. Nuclei with fiber connections to the cerebral cor-tex are collectively called specific thalamicnuclei; nuclei without any connection to thecortex but with connections to the brain stem are the nonspecific thalamic nuclei.

Clinical Note: Knowledge of the basic struc-ture of the thalamus is of practical importance be-cause motor disturbances and conditions of pain can be treated by stereotactic surgery at the thalamus.

A26 Cut surface of corpus callosum.

We describe the following in details....

Specific Thalamic Nuclei

Nonspecific Thalamic Nuclei

Anterior Nuclear Group

Medial Nuclear Group

Centromedian Nucleus

Lateral Nuclear Group

Ventral Nuclear Group

Lateral Geniculate Body

Medial Geniculate Body

Pulvinar

Frontal Section Through the Rostral Thalamus

Frontal Section Through the Caudal Thalamus