Functional localization in the trigeminal root

Abstract

✓ The composition of the trigeminal root was determined in this study by a combination of electrophysiological recording and stimulation of dissected root fibers in macaques, evaluation of deficits in man after posterior fossa root section, and microdissection in man and macaque. The roots in man and macaque were found anatomically similar. The sensory root contained three distinguishable but overlapping divisions with fibers relating to various peripheral functions and surfaces mixed within each division; no separate region contained fibers of a particular function, and no pattern of somatotopic localization could be determined within a division. The motor root contained sensory proprioceptive fibers, activated by jaw movement, and were found closely intermingled with motor fibers in all fascicles dissected. Accessory fibers (Dandy) were present in all dissections in man and macaque. They contained the same motor and sensory elements as the motor root which they joined. Human partial root sections via the posterior fossa did not exclusively diminish any single sensory modality, and an explanation is offered for the observation that generous surgical sections often result in only slight sensory loss.