Novel Venous Sinus of the Porus Trigeminus of Meckel's Cave: Anatomical and Radiological Study

Introduction: We present a novel sinus recently identified in the floor of the porus trigeminus of Meckel’s cave. This sinus is interposed between the superior and inferior petrosal sinuses, and due to its location, it can carry important surgical and clinical implications, as well as contribute to unusual presentations. A review of the current literature on similar variants in the region and the superior petrosal area is discussed, along with our cadaveric and radiological findings. Methods: Twenty-five latex-injected cadavers (50 sides) underwent dissection of the skull base. Specifically, the dural venous sinus structures located at the porus trigeminus were evaluated using a surgical microscope. In addition, a retrospective review of imaging of this area was observed to identify a sinus at this location. Results: For cadaveric specimens, the sinus of the porus trigeminus was seen on seven sides (14%) and this was compared to our histological and radiological findings. The sinuses always traveled in the floor of the porus trigeminus, were about 3 millimeter in width and variably connected to the superior petrosal sinus above but more often, with the inferior petrosal sinus or basilar venous plexus. One sinus drained directly into the cavernous sinus. Conclusion: Surgery in and around the opening to Meckel’s cave could encounter the dural venous sinus of the porus trigeminus. Knowledge of such a variant will minimize operative and interventional complications. Publication History Article published online: 27 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany