Anatomical Organization of the Trigeminal Nerve and Clinical Correlation in Microvascular Decompression for Trigeminal Neuralgia

Introduction: Trigeminal neuralgia (TN) is a debilitating facial pain disorder, most commonly caused by neurovascular compression of the trigeminal root entry zone. Pain typically follows the ophthalmic (V1), maxillary (V2), or mandibular (V3) distributions, yet the precise anatomical basis for these patterns remains poorly defined. This study aimed to delineate the organization of trigeminal nuclei and root fibers through cadaveric dissection and correlate these findings with clinical manifestations observed in patients undergoing microvascular decompression (MVD). Methods: Eight cadaveric brainstems (16 sides) and three cadaveric heads were dissected using skull base and white matter fiber dissection techniques. The mesencephalic, principal sensory, spinal, and motor trigeminal nuclei were identified and mapped. The trigeminal nerve was studied along its intraparenchymal, cisternal, and Meckel’s cave segments, including the course and topography of V1- V3 divisions. Relationships between sensory and motor fibers were analyzed in detail. For clinical correlation, a retrospective review was performed on 245 patients who underwent MVD for TN; 60 were excluded due to incomplete imaging or repeat procedures, leaving 185 cases. Preoperative MRI and intraoperative findings were assessed to determine the location of neurovascular compression (medial, superior, inferior, lateral) and correlated with the distribution of pain. Results: The trigeminal nuclei, intrapontine, cisternal, and Meckel's cave segments, along with the divisions of the nerve, were meticulously characterized. Motor fibers were consistently located superior to the sensory root in the intrapontine and cisternal segments, coursing posteroinferiorly in Meckel's cave and merging with the mandibular division before exiting via the foramen ovale. Sensory fibers demonstrated a reproducible topography: The V1 fibers were located medially and superiorly, the V2 fibers were located inferiorly and medially beneath the V1, and the V3 fibers constituted the largest and most lateral bundle. The clinical correlation confirmed these anatomical patterns: medial compression was predominantly associated with V1 pain, superior or inferior compression with V2 involvement, and lateral compression with V3-dominant symptoms. The extent of compression exerted influenced the distribution of symptoms, with extensive compression affecting multiple divisions (V1–V3) and isolated pain reflecting localized involvement. These findings were fully consistent with the cadaveric fiber organization. Conclusion: This study offers a comprehensive anatomical and clinical correlation of trigeminal nuclei and root fiber organization. Integrating meticulous cadaveric dissection with MVD outcomes, we demonstrate that the topographic distribution of pain in TN reflects the site of neurovascular compression along the trigeminal root. These findings contribute to an enhanced anatomical understanding and offer a practical framework for preoperative planning, facilitating more precise and individualized surgical strategies in the management of trigeminal neuralgia. Publication History Article published online: 27 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany