(0722) Revisiting the Anatomy of the Glossopharyngeal Nerve: A Microdissection Study

Introduction: The glossopharyngeal nerve (GPN) possesses sensory, motor, and parasympathetic functions, vital for taste perception, swallowing, and salivation. The anatomical depiction of the GPN morphology and branching patterns remains inconsistent within the anatomical literature. This study seeks to explore the extracranial distribution patterns of the GPN.

Methods: In total, 11 bisected cadaveric half-heads provided materials for this study. Cadaveric donors were obtained by the Anatomical Board of the State of Florida. The dissection and examination of the cadavers was carried out in the NSU MD Anatomy Laboratory​ beginning in July 2023. The dissection technique involved a lateral approach to the parapharyngeal space by removing the ramus of the mandible and muscles of mastication to expose the glossopharyngeal nerve as it winds around the stylopharyngeus. ​After initial gross dissection to remove the connective tissue and identify major nerves, stereomicroscopic dissection was performed to trace finer branches of the GPN and their interconnections.

Results: The GPN was divided into carotid sinus branches (CSNs), pharyngeal branches, and a glossal branch. The number of primary branches ranged from 2-6 before the terminal portion of the nerve pierced the lateral aspect of the root of the tongue near the insertion of the styloglossus muscle. Of the specimens, 5 had more than one carotid sinus nerve. Total branches to the pharyngeal plexus ranged from 2-6. Five specimens had a carotidopharyngeal trunk, which divided into CS and pharyngeal branches. Intercommunications between the pharyngeal or other vagal branches with the CS branch of the GPN were common. Other notable anastomoses were CSN receiving a branch from superior cervical sympathetic ganglion or superior laryngeal nerve.

Conclusions: The branching pattern and morphology of the glossopharyngeal nerve was highly variable across specimens. This pronounced individual variability underscores its complexity. A deeper understanding of the branching patterns and morphology of the GPN could notably enhance surgical procedures and patient outcomes.