The term trigeminal nuclei refers to brainstem nuclei that are primarily associated with the trigeminal nerve. They include the midbrain trigeminal nucleus in the midbrain tegmentum, the principal sensory nucleus of the trigeminal nerve and the motor nucleus of the trigeminal nerve in the pontine tegmentum, and the spinal trigeminal nucleus, which has subnuclei in both the pontine tegmentum and the medulla ( Carpenter-1983 ).