thalamussen

Thalamussen is the Danish or Norwegian definite form of the thalamus, the paired gray-matter structure that forms the central relay station of the brain. The thalamus sits on either side of the third ventricle, within the diencephalon, and is organized into multiple nuclei with distinct connections and functions.

Function and organization: The thalamus acts as a relay and processing hub for most sensory pathways (except olfaction) and for corticothalamic and basal ganglia signals. It integrates and forwards information to the cerebral cortex and participates in attention, arousal, and sleep via thalamocortical circuits. Major relay nuclei include the lateral geniculate nucleus for vision, the medial geniculate nucleus for audition, and the ventral posterior nuclei for somatosensory information; association and motor-related nuclei include the ventral lateral/anterior nuclei and the mediodorsal and pulvinar nuclei.

Clinical relevance: Lesions in the thalamus can cause sensory loss contralaterally, thalamic pain syndrome, movement disorders, aphasia or neglect, depending on the affected nuclei. Thalamic strokes and hemorrhages are known clinical entities. The thalamus also participates in consciousness and arousal, in conjunction with brainstem structures.

Vascular supply and development: The thalamus receives blood from branches of the posterior cerebral artery, including thalamogeniculate and posterior choroidal arteries, with perforating arteries supplying the medial region. Embryonically, it develops from the diencephalon and becomes a densely interconnected relay network.

See also: diencephalon, hypothalamus, basal ganglia, limbic system.