The ventral posterior nucleus sits low in the outer part of the thalamus, towards its back. It is the thalamus’s touch relay: its outer half, the VPL, passes on signals from the body, its inner half, the VPM, those from the face, both to the somatosensory cortex of the postcentral gyrus. [1][2][3]
The 3D brain needs JavaScript. The text below still says where the ventral posterior nucleus is and what it does.
Opens cut by a front (coronal) slice through the thalamus, which holds the ventral posterior nucleus. Drag to turn, pinch or scroll to zoom, tap any part to name it; .
Not a separate shape in this atlas; lit: the part that holds it. Lit: the whole thalamus, on both sides. The VPL and VPM are nuclei inside the thalamus; BodyParts3D has no shape for either (its only thalamic nuclei are the two geniculate bodies), so the whole thalamus is lit and nothing is drawn at a guessed point. [4][1]
Lit here: the thalamus, the part that holds the ventral posterior nucleus — see it on its own page.
Where it is
The Y-shaped internal medullary lamina divides each thalamus into anterior, medial and lateral groups; the ventral nuclei form the lower tier of the lateral group and are split into ventral anterior, ventral lateral and ventral posterior. [1]
It has two main halves side by side: the ventral posterolateral nucleus (VPL) on the outside and the ventral posteromedial nucleus (VPM), its inner neighbour. [4][3]
Inside the VPM the face’s signals are laid out front to back: position-sense endings at the front, touch in the middle and pain at the back. [3]
What it does
The VPL takes in second-order neurons of the medial lemniscus and the spinothalamic tract, carrying the body’s touch, body position, pain and temperature; its third-order neurons project to the primary somatosensory cortex in the postcentral gyrus. [2][4]
The VPM does the same for the face and mouth, fed by the trigeminal tracts, and also sends its signals to the somatosensory cortex. [3]
Taste: the medial-most part of the VPM receives taste fibres from the solitary nucleus of the medulla and sends them on to the gustatory cortex, not to the somatosensory cortex. [3]
Overall it relays and regulates touch, body position, pain, temperature, itch, taste and arousal. [4]
A small part of the VPL (its oral part, VPLo) projects to the motor cortex instead. [2]
Other names
VPL = ventral posterolateral nucleus, VPM = ventral posteromedial nucleus; together with the ventral intermediate nucleus they make up the ventral posterior nucleus. The taste part of the VPM is sometimes called the accessory arcuate nucleus. [4][3]
Size
The model has no shape for the ventral posterior nucleus itself, so it is not measured here. The left thalamus that holds it measures about 37 mm front to back, 24 mm top to bottom and 24 mm side to side on this model (the box it fits in, not its volume). [5]
Facts describe anatomy and normal function only. The 3D model is the adult male BodyParts3D brain (credits and licence); real brains vary in size and shape, so its measurements describe one model, not anyone’s brain.