 The ventral trigeminal tract connects the two major components of the brainstem trigeminal complex – the principal, or main sensory nucleus and the spinal trigeminal nucleus, to the ventral posteromedial nucleus of the thalamus.The ventral trigeminal tract is also called the anterior trigeminal lemniscus.The first order neurons (from the trigeminal ganglion) enter the pons and synapse in the principal (chief sensory) nucleus or spinal trigeminal nucleus.