Editing Trigeminal nerve (section)

==={{anchor|Main trigeminal nucleus}}Principal nucleus===
The [[principal sensory nucleus of trigeminal nerve|principal nucleus]] represents touch-pressure sensation from the face. It is located in the pons, near the entrance for the fifth nerve. Fibers carrying touch-position information from the face and mouth via cranial nerves V, VII, IX, and X are sent to this nucleus when they enter the brainstem.

The principal nucleus contains a touch-position sensory map of the face and mouth, just as the spinal trigeminal nucleus contains a complete pain-temperature map. This nucleus is analogous to the [[dorsal column]] nuclei (the [[Gracile nucleus|gracile]] and [[cuneate nucleus|cuneate]] nuclei) of the spinal cord, which contain a touch-position map of the rest of the body.

From the principal nucleus, secondary fibers cross the midline and ascend in the [[Anterior trigeminothalamic tract|ventral trigeminothalamic tract]] to the contralateral [[thalamus]]. The ventral trigeminothalamic tract runs parallel to the [[medial lemniscus]], which carries touch-position information from the rest of the body to the thalamus.

Some sensory information from the teeth and jaws is sent from the principal nucleus to the [[Anatomical terms of location#Other directional terms|ipsilateral]] thalamus via the small [[dorsal trigeminal tract]]. Touch-position information from the teeth and jaws of one side of the face is represented bilaterally in the thalamus and cortex.