Posterior trigeminothalamic tract

The posterior trigeminothalamic tract (a.k.a. the dorsal trigeminothalamic tract) is a crucial component of the trigeminal lemniscus, comprising second-order neurons within the trigeminal sensory system. These neurons primarily originate from the principal sensory nucleus of the trigeminal nerve and are responsible for transmitting sensory information related to touch and pressure from the face and head. The fibers in this tract remain ipsilateral, meaning they do not cross over to the opposite side, and ascend directly to the ventral posterior medial (VPM) nucleus of the thalamus.

It is important to note that some trigeminothalamic fibers from the main sensory nucleus do decussate, or cross over, to ascend to the VPM nucleus on the contralateral side. These fibers form part of the anterior or ventral trigeminothalamic tract. However, they are fewer in number compared to the majority of trigeminothalamic second-order neurons from the principal sensory nucleus, which ascend within the posterior trigeminothalamic tract to reach the VPM nucleus on the ipsilateral side.

Following processing in the thalamus, the sensory information is projected to the cerebral cortex for further interpretation and response.