Internuclear Connections of the Trigeminal Nuclei

Internuclear Connections of the Trigeminal Nuclei

Only a few secondary trigeminal fibers enter the medial longitudinal fasciculus. The majority of fibers run primarily uncrossed in the dorsolateral region of the tegmentum to the motor nuclei of cranial nerves; they form the basis of numerous important re-flexes. Crossed and uncrossed fibers run to the facial nucleus as the basis of the cornealreflex (eyelids close upon touching the cornea). There are connections to the superior salivatory nucleus for the lacrimal reflex. Fibers to the hypoglossal nucleus, to the ambiguous nucleus, and to the anterior horn cells of the cervical spinal cord (cells of origin of the phrenic nerve) are the basis of the sneezing reflex. The pharyngeal reflex is based on fiber connections to the ambiguous nucleus, the posterior vagus nucleus, and the motor nucleus of the trigeminal nerve. Connections with the posterior vagus nucleus are the basis of the oculocardial re-flex(slow heart rate upon pressure on theeyeballs).