| Ventral posteromedial nucleus | |
| Latin: | nucleus ventralis posteromedialis thalami |
The ventral posteromedial nucleus (VPM) is a nucleus of the thalamus and serves an analogous somatosensory relay role for the ascending trigeminothalamic tracts as its lateral neighbour the ventral posterolateral nucleus serves for dorsal column–medial lemniscus pathway 2nd-order neurons.
The VPM receives second-order general somatic afferent fibers from the anterior (ventral) and posterior (dorsal) trigeminothalamic tract which convey general somatic afferent sensory information from the face and oral cavity (including touch, pressure, temperature, pain, and propriception). Proprioceptive synapses are situated anteriorly, ones mediating touch in the middle, and nociceptive ones posteriorly.[1]
Third-order neurons in turn project to the somatosensory area in the postcentral gyrus.
The VPM receives second-order taste special visceral afferent afferents from the solitary nucleus. These synapse in the medial-most portion of the VPM (which is sometimes referred to as the accessory arcuate nucleus).[2]
Third-order neurons in turn project to the gustatory cortex.
The VPM likely also receives some general visceral afferents from the solitary tract conveying non-nociceptive visceral conscious sensations.[3]
The parvicellular part of the ventroposterior medial nucleus (VPMpc) is argued by some as not an actually part of the VPM, because it does not project to the somatosensory cortex as the remainder of the VPM does, and therefore should be called the ventromedial nucleus (VMb) instead.[4]