ventralposterior

The ventral posterior nucleus is a key thalamic relay for somatosensory information and is often referred to as the ventral posterior complex, comprising two main parts: the ventral posterior lateral nucleus (VPL) and the ventral posterior medial nucleus (VPM). It lies in the ventral posterior region of the thalamus and serves as the principal gateway transmitting somatosensory signals to the cerebral cortex.

Inputs to the ventral posterior nucleus are modality- and body-specific. The VPL receives ascending input from the dorsal column–medial lemniscus system and the spinothalamic tract, conveying touch, proprioception, nociception, and temperature from the body. The VPM receives input from the trigeminothalamic pathway, conveying similar modalities from the face and oral cavity. Together, these nuclei integrate and relay somatosensory information to the cortex.

Outputs from the ventral posterior nucleus project to the primary somatosensory cortex (areas 3, 1, and 2) via thalamocortical radiations through the posterior limb of the internal capsule and corona radiata. The nuclei are organized somatotopically, with body information routed through the VPL and facial information through the VPM.

Clinical relevance includes contralateral sensory loss following thalamic damage, which can occur with stroke or injury to the ventral posterior complex. A well-known consequence is thalamic pain syndrome (Dejerine-Roussy), characterized by chronic central pain after thalamic insult. The ventral posterior nucleus receives its blood supply mainly from thalamogeniculate arteries arising from the posterior cerebral artery.

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