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either of two large ovoid structures (the dorsal thalamus or simply thalamus and the ventral thalamus) composed of gray matter and located at the base of the cerebrum. (See also brain.) adj., adj thalam´ic. The thalamus functions as a relay station in which sensory pathways of the spinal cord and brainstem form synapses on their way to the cerebral cortex. Specific locations in the thalamus are related to specific areas on the body surface and in the cerebral cortex. A sensory impulse from the body surface travels upward to the thalamus, where it is received as a primitive sensation and then is sent on to the cerebral cortex for interpretation as to location, character, and duration. The thalamus has numerous connections to other areas of the brain as well, and these are thought to be important in the integration of cerebral, cerebellar, and brainstem activity.
ventral thalamus the subthalamic tegmental region, a transitional region of the diencephalon interposed between the (dorsal) thalamus, the hypothalamus, and the tegmentum of the mesencephalon; it includes the subthalamic nucleus, Forel's fields, and the zona incerta. Called also subthalamus.
That part of the diencephalon that lies wedged between the thalamus on the posterior side and the cerebral peduncle anteriorly, lateral to the posterior half of the hypothalamus from which it cannot be sharply delineated. It is composed of the subthalamic nucleus (corpus luysi), the zona incerta, and the fields of Forel. Laterally it expands in a winglike fashion into the reticular nucleus of the thalamus; caudally it is continuous with the midbrain tegmentum.
Synonym(s): ventral thalamus
That part of the diencephalon that lies wedged between the thalamus on the dorsal side and the cerebral peduncle ventrally, lateral to the dorsal half of the hypothalamus, from which it cannot be sharply delineated. It is composed of the subthalamic nucleus (corpus luysi), the zona incerta, and the fields of Forel; laterally, it expands in a winglike fashion into the reticular nucleus of the thalamus; caudally, it is continuous with the midbrain tegmentum.