Background The posterior petroclinoid dural fold (commonly referred to as a ligament) forms the roof of the trigeminal porus and the roof of the petroclival venous confluence. It lies in close proximity to the oculomotor nerve that crosses it. Due to the low availability of research material, only a few cadaveric studies have been conducted on the microsurgical anatomy of the petroclinoid ligament in cases of its ossification. Thus our report complements earlier studies and provides detailed data on the spatial relationships between the ossified posterior petroclinoid ligament and the trigeminal, oculomotor, and abducens nerves, with special attention to the topographical relationships within the petroclival venous confluence and Dorello's canal. Case Description Bilateral massive ossification of the posterior petroclinoid ligament was observed during the dissection of a 76-year-old female cadaver. The presence of an osseous bridge over the trigeminal notch was also detected on the left side. No narrowing of the space occupied by the petroclival venous confluence was observed. However, the dural sheath of the oculomotor nerve was fixed much more than usual. Conclusions Because the ossification of the posterior petroclinoid ligament may be considered a factor influencing diagnostic and surgical procedures, neurosurgeons and neuroradiologists should be aware of this variation. Ossification of the posterior petroclinoid ligament may also potentially result in greater susceptibility of the oculomotor nerve to injury.