ventralanterior

The ventral anterior nucleus (VA) is a thalamic nucleus that forms part of the ventral tier of the thalamus. It is located anterior to the ventral lateral nucleus and serves as a relay hub within motor-related thalamocortical circuits.

Afferent and efferent connections place the VA within the basal ganglia–thalamo-cortical loop. It receives heavy input from basal ganglia output structures, particularly the internal segment of the globus pallidus and the substantia nigra pars reticulata, and projects to motor-associated areas of the cerebral cortex, including premotor and supplementary motor regions. Through these connections, the VA contributes to the regulation and planning of voluntary movements and the coordination of motor programs with other thalamic and cortical regions.

Functionally, the VA participates in translating motor planning into coordinated motor commands. It acts as a relay that information from basal ganglia output can influence premotor and motor cortical activity, shaping voluntary movement. The VA works in concert with nearby thalamic nuclei, such as the ventral lateral nucleus, to modulate motor execution.

Clinical significance varies with lesion or dysfunction of the VA or surrounding thalamic tissue. Thalamic stroke or focal lesions can produce contralateral motor deficits, including weakness or impaired movement coordination. Deep brain stimulation targeting thalamic nuclei, including VA, has been used in the management of certain movement disorders such as tremor and dystonia in selected cases.