A Cadaveric Study of the Variations of the Otic Ganglion

Abstract

Introduction The otic ganglion is located in the infratemporal fossa and contains postganglionic parasympathetic cell bodies for the innervation of the parotid gland. The small size and complicated location of the ganglion makes it particularly difficult to visualize and dissect. Therefore, there are very few human studies describing its syntropy, morphology, and branches. The goal of this study was to investigate the location and size of the otic ganglion, the relationship of the otic ganglion to the mandibular nerve, and to determine a dissection approach that is fast, accurate, and causes minimal destruction to surrounding structures. Materials and Methods: 11 adult (5 male and 6 female) cadavers donated to the Human Anatomy Program at University of Texas Health Science Center at San Antonio were dissected bilaterally. Each otic ganglion was considered a separate sample. Two dissection approaches were studied: a traditional deep infratemporal fossa dissection and a medial dissection via destruction of the torus tubarius and surrounding nasopharynx structures. Results: The otic ganglion was present in 14 out of 21 (66.7%) cadaver samples. 9 (64.3%) otic ganglions presented as the classical description: a separate entity independent from the mandibular nerve. Meanwhile, 5 (35.7%) otic ganglions presented as swellings of the mandibular nerve. All 14 (100%) otic ganglions were located inferior to the foramen ovale, within the infratemporal fossa. The otic ganglions averaged 5.14mm in height, 6.88mm in length, and 1.89mm in width. While the traditional deep infratemporal fossa dissection was faster (average 9 min.), the otic ganglia were best visualized from the medial nasopharynx approach. Conclusion: Thorough documentation of the human otic ganglia's prevalence, size, location, and details pertaining to dissection approaches will help students more easily identify the ganglia during gross anatomy dissections and also aid head and neck surgeons, dentists, and neurosurgeons in understanding the intricacies of the structure.