Question

Ascending afferents from both the medial lemniscal pathway and the spinothalamic pathway of the spinal cord synapse in the ventral posterior nucleus of the thalamus (VPN). The VPN has two parts: the medial VPN and the lateral VPN.

(a) What somatosensory afferents synapse in each of these two areas and

(b) to which 3 areas do neurons from the VPN project?

Answer 1

a). The ventropostero nucleus has 2 parts , medial vpn and lateral vpn .

The ventro postero lateral nucleus recieves input from medial lemniscus of dorsal column and neospinothalamic tract .

Ventro postero medial nucleus recieves input from , trigeminothalamic tract , both its ventral and dorsal pathways

b). Neurons from vpn projects to , primary somatosensory cortex of brain , which has broadmans area 3, 1,2 in the postcentral gyrus .

Mostly 3rd order neurons are located in the thalamus, the ascending pathways relay in thalamus from which it relays into cortical areas of the brain . The afferent pathway has a dorsal , ventral and lateral spinothalamic pathways .

Thalamic nuclei is divided into ventral , lateral , posterior, anterior and medial. Posterior nuclei has visual and auditory relay . Anterior nuclei deals with attention, memory and learning. Lateral groups has motor and sensory relay .