Trigeminal System
The trigeminal system is the somatosensory system for the face, which is clinically tested in the cranial nerve exam. For the trigeminal system it is important to remember that the descending tract of the trigeminal nerve, which serves pain and temperature, descends to the level of the upper cervical spinal cord and then axons from the 2nd order neurons cross over to the opposite side and ascend to the ventral posterior medial (VPM) nucleus of the thalamus.
