Abstract
The mesencephalic nucleus of the trigeminus is a group of cells found, in the tectum of the mesencephalon and extends from the level of the posterior commissure to the level of the chief motor nucleus of the trigeminus. This investigation was a study of the responses of the cells in the mesencephalic nucleus of the cat to section of the motor and sensory branches of the mandibular nerve. | The nucleus is composed of two or more distinct types of cells that participate in either a relay or sensory perception function. These cells give off at least one process which courses with the processes of the other mesencephalic cells to form the mesencephalic root of the trigeminal nerve. The root usually lies lateral to the mesencephalic cell bodies along the dorsolateral margin of the central gray matter and courses in a ventrolateral direction. The mesencephalic root is thought to contain both an ascending and descending tract of fibers (Cajal, 1896).