THE BULBAR PROJECTION OF THE TRIGEMINAL NERVE

Abstract

The character and distribution of action potentials recorded from points within the medulla of the cat upon electrical stimulation of peripheral branches of the 3 trigeminal divisions are described. In their course in the sensory root and spinal 5th tract, fast conducting fibers of the 3 trigeminal divisions are laminated in a dorso-ventral order which is the inverse of their distribution in the face. Fibers of the mandibular division are detected as far caudally as the obex; those of the maxillary and ophthalmic divisions as far caudally as the 1st cervical segment. The neurons of the spinal 5th nucleus fired by primary fibers of the 3 trigeminal divisions are laminated in a dorso-ventral order similar to that of the spinal 5th tract, but with greater overlap. Secondary trigeminal pathways pass diffusely across the reticular formation to the ventro-medial part of the opposite side of the medulla and ascend in relation to the medial lemniscus.